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Sample records for 75-kev proton impact

  1. Hydrogen Formation by Proton Impact on Positronium

    SciTech Connect

    Merrison, J.; Bluhme, H.; Chevallier, J.; Deutch, B.; Hvelplund, P.; Jo Knudsen, H.; Poulsen, M.; Charlton, M.

    1997-04-01

    Hydrogen formation has been observed following proton impact on positronium. This is the first observation of charge exchange involving a positronium target. The cross section for hydrogen formation has been experimentally determined at proton energies of 11.3, 13.3, and 15.8keV. Values of {sigma}{sub H}=26({plus_minus}9), 7.8({plus_minus}2.3), and 7.6({plus_minus}4.4){times}10{sup -16}cm{sup 2} were obtained, in reasonable agreement with recent calculations. {copyright} {ital 1997} {ital The American Physical Society}

  2. Impact of variable RBE on proton fractionation

    SciTech Connect

    Dasu, Alexandru; Toma-Dasu, Iuliana

    2013-01-15

    Purpose: To explore the impact of variable proton relative biological effectiveness (RBE) on dose fractionation for clinically relevant situations. A generic RBE = 1.1 is generally used for isoeffect calculations, while experimental studies showed that proton RBE varies with tissue type, dose, and linear energy transfer (LET). Methods: An analytical expression for the LET and {alpha}/{beta} dependence of the linear-quadratic (LQ) model has been used for proton simulations in parallel with the assumption of a generic RBE = 1.1. Calculations have been performed for ranges of LET values and fractionation sensitivities to describe clinically relevant cases, such as the treatment of head and neck and prostate tumors. Isoeffect calculations were compared with predictions from a generic RBE value and reported clinical results. Results: The generic RBE = 1.1 appears to be a reasonable estimate for the proton RBE of rapidly growing tissues irradiated with low LET radiation. However, the use of a variable RBE predicts larger differences for tissues with low {alpha}/{beta} (both tumor and normal) and at low doses per fraction. In some situations these differences may appear in contrast to the findings from photon studies highlighting the importance of accurate accounting for the radiobiological effectiveness of protons. Furthermore, the use of variable RBE leads to closer predictions to clinical results. Conclusions: The LET dependence of the RBE has a strong impact on the predicted effectiveness of fractionated proton radiotherapy. The magnitude of the effect is modulated by the fractionation sensitivity and the fractional dose indicating the need for accurate analyses both in the target and around it. Care should therefore be employed for changing clinical fractionation patterns or when analyzing results from clinical studies for this type of radiation.

  3. Predicted impacts of proton temperature anisotropy on solar wind turbulence

    SciTech Connect

    Klein, K. G.; Howes, G. G.

    2015-03-15

    Particle velocity distributions measured in the weakly collisional solar wind are frequently found to be non-Maxwellian, but how these non-Maxwellian distributions impact the physics of plasma turbulence in the solar wind remains unanswered. Using numerical solutions of the linear dispersion relation for a collisionless plasma with a bi-Maxwellian proton velocity distribution, we present a unified framework for the four proton temperature anisotropy instabilities, identifying the associated stable eigenmodes, highlighting the unstable region of wavevector space and presenting the properties of the growing eigenfunctions. Based on physical intuition gained from this framework, we address how the proton temperature anisotropy impacts the nonlinear dynamics of the Alfvénic fluctuations underlying the dominant cascade of energy from large to small scales and how the fluctuations driven by proton temperature anisotropy instabilities interact nonlinearly with each other and with the fluctuations of the large-scale cascade. We find that the nonlinear dynamics of the large-scale cascade is insensitive to the proton temperature anisotropy and that the instability-driven fluctuations are unlikely to cause significant nonlinear evolution of either the instability-driven fluctuations or the turbulent fluctuations of the large-scale cascade.

  4. The Impact of Neutrons in Clinical Proton Therapy.

    PubMed

    Schneider, Uwe; Hälg, Roger

    2015-01-01

    In proton therapy, high-energy proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long-term health of cancer patients. Due to the high biological effectiveness of neutrons with regard to cancer induction, small neutron doses can be important. Published comparisons of neutron dose measurements and the corresponding estimates of cancer risk between different treatment modalities differ over orders of magnitude. In this report, the controversy about the impact of the neutron dose in proton therapy is critically discussed and viewed in the light of new epidemiological studies. In summary, the impact of neutron dose on cancer risk can be determined correctly only if the dose distributions are carefully measured or computed. It is important to include not only the neutron component into comparisons but also the complete deposition of energy as precisely as possible. Cancer risk comparisons between different radiation qualities, treatment machines, and techniques have to be performed under similar conditions. It seems that in the past, the uncertainty in the models which lead from dose to risk were overestimated when compared with erroneous dose comparisons. Current risk models used with carefully obtained dose distributions predict a second cancer risk reduction for active protons vs. photons and a more or less constant risk of passive protons vs. photons. Those findings are in general agreement with newly obtained epidemiologically results.

  5. Efficiencies for production of nitrogen oxides by proton impact in air

    NASA Astrophysics Data System (ADS)

    Rahman, Mahbubur; Cooray, Vernon; Possnert, Göran

    2013-03-01

    We present the first laboratory measurements of nitrogen oxides generated by proton impact in air. Experiments were conducted at the Tandem Laboratory of Uppsala University. A proton beam with known current and energy was injected into an air tight ionising chamber for a fixed time duration and the resulting nitrogen oxides were measured by the method of chemiluminescence. The data are presented in terms of number of produced NOX (NO+NO2) molecules for different proton energy, proton beam current and duration. The efficiency for NOX production by proton impact in air can on average be estimated to about 0.2 NOX molecules per ion-pair based on 1 cm diameter proton beam with energies from 2 to 4 MeV and varied currents from 0.1 to 10 nA.

  6. Double excitation of He and H{sup {minus}} by fast proton and anti-proton impact

    SciTech Connect

    Hino, Ken-ichi |; Moribayashi, K.; Nagase, M.; Matsuzawa, M.; Kimura, M. |

    1993-12-31

    Theoretical investigation has been made on double excitation processes of He and H{sup {minus}} by fast proton and anti-proton impact in the MeV/u-energy region. The cross sections are calculated by use of both the close-coupling and the perturbation expansion methods, and the wave functions of target atoms are generated based on the hyperspherical coordinate method. The excitation to the 2p{sup 2} {sup 1}D{sup e} state of H{sup {minus}} by anti-proton impact is dominant by about three times in comparison with that by proton impact at the incident energy of 0.1 MeV/u. The spectral shape of an ejected electron from the 2s2p {sup 1}p{sup o} state of H{sup {minus}} at the incident energy of 1.5 MeV/u is consistent with the line profile of the H{sup {minus}} photodetachment observed by Bryant et al.

  7. Impact of Solar Proton Events on High Latitude Ionospheric Conditions

    NASA Astrophysics Data System (ADS)

    Aslam, A. M.; Gwal, Ashok Kumar; Mansoori, Azad Ahmad

    2016-07-01

    We investigate the ionospheric response to the solar protons which are accelerated to different energies (MeV-GeV) and thought to be originated at the solar atmosphere during the various energetic phenomena knows as solar transients viz. Solar Flares, Coronal Mass Ejections (CMEs). These transients are believed to be a manifestation of same energy release processes from a highly complex condition in the magnetic field configuration on the solar surface. We have taken six solar proton events (SPE) of solar cycle 23rd for analysis in the various energy bands of the protons. In order to find the ionospheric responses to these incoming solar protons ionospheric total electron content (TEC) is taken as the characteristic parameter. We have taken the data observed by GOES satellites which provides the data for different energy channels (0.8-4 MeV, 4-9 MeV, 9-15 MeV, 15-40 MeV, 40-80 MeV, 80-165 MeV, and 165-500 MeV). The enhancement in peak TEC (∆TEC) was then obtained for the high latitude station Davis (Lat-68.35, Lon 77.58). To find the association of this enhancement with proton flux characteristics we derived the correspondence between spectral indices and ∆TEC. We obtained a strong correlation (0.84) to exist between the spectral indices and ∆TEC.

  8. Thermomechanical response of Large Hadron Collider collimators to proton and ion beam impacts

    NASA Astrophysics Data System (ADS)

    Cauchi, Marija; Assmann, R. W.; Bertarelli, A.; Carra, F.; Cerutti, F.; Lari, L.; Redaelli, S.; Mollicone, P.; Sammut, N.

    2015-04-01

    The CERN Large Hadron Collider (LHC) is designed to accelerate and bring into collision high-energy protons as well as heavy ions. Accidents involving direct beam impacts on collimators can happen in both cases. The LHC collimation system is designed to handle the demanding requirements of high-intensity proton beams. Although proton beams have 100 times higher beam power than the nominal LHC lead ion beams, specific problems might arise in case of ion losses due to different particle-collimator interaction mechanisms when compared to protons. This paper investigates and compares direct ion and proton beam impacts on collimators, in particular tertiary collimators (TCTs), made of the tungsten heavy alloy INERMET® 180. Recent measurements of the mechanical behavior of this alloy under static and dynamic loading conditions at different temperatures have been done and used for realistic estimates of the collimator response to beam impact. Using these new measurements, a numerical finite element method (FEM) approach is presented in this paper. Sequential fast-transient thermostructural analyses are performed in the elastic-plastic domain in order to evaluate and compare the thermomechanical response of TCTs in case of critical beam load cases involving proton and heavy ion beam impacts.

  9. Technical Note: Spatial resolution of proton tomography: Impact of air gap between patient and detector

    SciTech Connect

    Schneider, Uwe; Besserer, Juergen; Hartmann, Matthias

    2012-02-15

    Purpose: Proton radiography and tomography were investigated since the early 1970s because of its low radiation dose, high density resolution, and ability to image directly proton stopping power. However, spatial resolution is still a limiting factor. In this note, preliminary results of the impact of an air gap between detector system and patient on spatial resolution are presented. Methods: Spatial resolution of proton radiography and tomography is governed by multiple Coulomb scattering (MCS) of the protons in the patient. In this note, the authors employ Monte Carlo simulations of protons traversing a 20 cm thick water box. Entrance and exit proton coordinate measurements were simulated for improved spatial resolution. The simulations were performed with and without a 5 cm air gap in front of and behind the patient. Loss of spatial resolution due to the air gap was studied for protons with different initial angular confusion. Results: It was found that spatial resolution is significantly deteriorated when a 5 cm air gap between the position sensitive detector and the patient is included. For a perfect parallel beam spatial resolution worsens by about 40%. Spatial resolution is getting worse with increasing angular confusion and can reach 80%. Conclusions: When proton radiographies are produced by measuring the entrance and exit coordinates of the protons in front of and behind the patient the air gap between the detector and the patient can significantly deteriorate the spatial resolution of the system by up to 80%. An alternative would be to measure in addition to the coordinates also the exit and entrance angles of each proton. In principle, using the air gap size and proton angle, images can be reconstructed with the same spatial resolution than without air gap.

  10. Empirical determination of solar proton access to the atmosphere: Impact on polar flight paths

    NASA Astrophysics Data System (ADS)

    Neal, Jason J.; Rodger, Craig J.; Green, Janet C.

    2013-07-01

    Violent expulsions on the Sun's surface release high energy solar protons that ultimately affect HF communication used by aircraft. The geomagnetic field screens the low altitude equatorial region, but these protons can access the atmosphere over the poles. The latitudes over which the solar protons can reach vary with geomagnetic indices such as Kp and Dst. In this study we use observations from low Earth orbit to determine the atmospheric access of solar protons and hence the flights paths most likely to be affected. Observations taken by up to six polar orbiting satellites during 15 solar proton events are analyzed. From this we determine 16,850 proton rigidity cutoff estimates across three energy channels. Empirical fits are undertaken to estimate the most likely behavior of the cutoff dependence with geomagnetic activity. The changing Kp value is found to lead the variation in the cutoffs by ~3 h. We provide simple equations by which the geomagnetic latitude at which the protons impact the atmosphere can be determined from a given Kp or Dst value. The variation found in the cutoff with Kp is similar to that used in existing operational models, although we suggest that a ~1-2° equatorward shift in latitude would provide greater accuracy. We find that a Kp predictive model can provide additional warning to the variation in proton cutoffs. Hence, a prediction of the cutoff latitudes can be made ~3 h to as much as 7 h into the future, meeting suggested minimum planning times required by the aviation industry.

  11. Impact of high energy high intensity proton beams on targets: Case studies for Super Proton Synchrotron and Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Tahir, N. A.; Sancho, J. Blanco; Shutov, A.; Schmidt, R.; Piriz, A. R.

    2012-05-01

    The Large Hadron Collider (LHC) is designed to collide two proton beams with unprecedented particle energy of 7 TeV. Each beam comprises 2808 bunches and the separation between two neighboring bunches is 25 ns. The energy stored in each beam is 362 MJ, sufficient to melt 500 kg copper. Safety of operation is very important when working with such powerful beams. An accidental release of even a very small fraction of the beam energy can result in severe damage to the equipment. The machine protection system is essential to handle all types of possible accidental hazards; however, it is important to know about possible consequences of failures. One of the critical failure scenarios is when the entire beam is lost at a single point. In this paper we present detailed numerical simulations of the full impact of one LHC beam on a cylindrical solid carbon target. First, the energy deposition by the protons is calculated with the FLUKA code and this energy deposition is used in the BIG2 code to study the corresponding thermodynamic and the hydrodynamic response of the target that leads to a reduction in the density. The modified density distribution is used in FLUKA to calculate new energy loss distribution and the two codes are thus run iteratively. A suitable iteration step is considered to be the time interval during which the target density along the axis decreases by 15%-20%. Our simulations suggest that the full LHC proton beam penetrates up to 25 m in solid carbon whereas the range of the shower from a single proton in solid carbon is just about 3 m (hydrodynamic tunneling effect). It is planned to perform experiments at the experimental facility HiRadMat (High Radiation Materials) at CERN using the proton beam from the Super Proton Synchrotron (SPS), to compare experimental results with the theoretical predictions. Therefore simulations of the response of a solid copper cylindrical target hit by the SPS beam were performed. The particle energy in the SPS beam is 440

  12. Experimental stand for studying the impact of laser-accelerated protons on biological objects

    NASA Astrophysics Data System (ADS)

    Burdonov, K. F.; Eremeev, A. A.; Ignatova, N. I.; Osmanov, R. R.; Sladkov, A. D.; Soloviev, A. A.; Starodubtsev, M. V.; Ginzburg, V. N.; Kuz'min, A. A.; Maslennikova, A. V.; Revet, G.; Sergeev, A. M.; Fuchs, J.; Khazanov, E. A.; Chen, S.; Shaykin, A. A.; Shaikin, I. A.; Yakovlev, I. V.

    2016-04-01

    An original experimental stand is presented, aimed at studying the impact of high-energy protons, produced by the laser-plasma interaction at a petawatt power level, on biological objects. In the course of pilot experiments with the energy of laser-accelerated protons up to 25 MeV, the possibility is demonstrated of transferring doses up to 10 Gy to the object of study in a single shot with the magnetic separation of protons from parasitic X-ray radiation and fast electrons. The technique of irradiating the cell culture HeLa Kyoto and measuring the fraction of survived cells is developed. The ways of optimising the parameters of proton beams and the suitable methods of their separation with respect to energy and transporting to the studied living objects are discussed. The construction of the stand is intended for the improvement of laser technologies for hadron therapy of malignant neoplasms.

  13. Impact of proton irradiation on deep level states in n-GaN

    SciTech Connect

    Zhang, Z.; Arehart, A. R.; Cinkilic, E.; Ringel, S. A.; Chen, J.; Zhang, E. X.; Fleetwood, D. M.; Schrimpf, R. D.; McSkimming, B.; Speck, J. S.

    2013-07-22

    Deep levels in 1.8 MeV proton irradiated n-type GaN were systematically characterized using deep level transient spectroscopies and deep level optical spectroscopies. The impacts of proton irradiation on the introduction and evolution of those deep states were revealed as a function of proton fluences up to 1.1 × 10{sup 13} cm{sup −2}. The proton irradiation introduced two traps with activation energies of E{sub C} - 0.13 eV and 0.16 eV, and a monotonic increase in the concentration for most of the pre-existing traps, though the increase rates were different for each trap, suggesting different physical sources and/or configurations for these states. Through lighted capacitance voltage measurements, the deep levels at E{sub C} - 1.25 eV, 2.50 eV, and 3.25 eV were identified as being the source of systematic carrier removal in proton-damaged n-GaN as a function of proton fluence.

  14. Impact of Mutation on Proton Transfer Reactions in Ketosteroid Isomerase: Insights from Molecular Dynamics Simulations

    PubMed Central

    Chakravorty, Dhruva K.; Hammes-Schiffer, Sharon

    2010-01-01

    The two proton transfer reactions catalyzed by ketosteroid isomerase (KSI) involve a dienolate intermediate stabilized by hydrogen bonds with Tyr14 and Asp99. Molecular dynamics simulations based on an empirical valence bond model are used to examine the impact of mutating these residues on the hydrogen-bonding patterns, conformational changes, and van der Waals and electrostatic interactions during the proton transfer reactions. While the rate constants for the two proton transfer steps are similar for wild-type (WT) KSI, the simulations suggest that the rate constant for the first proton transfer step is smaller in the mutants due to the significantly higher free energy of the dienolate intermediate relative to the reactant. The calculated rate constants for the mutants D99L, Y14F, and Y14F/D99L relative to WT KSI are qualitatively consistent with the kinetic experiments indicating a significant reduction in the catalytic rates along the series of mutants. In the simulations, WT KSI retained two hydrogen-bonding interactions between the substrate and the active site, while the mutants typically retained only one hydrogen-bonding interaction. A new hydrogen-bonding interaction between the substrate and Tyr55 was observed in the double mutant, leading to the prediction that mutation of Tyr55 will have a greater impact on the proton transfer rates for the double mutant than for WT KSI. The electrostatic stabilization of the dienolate intermediate relative to the reactant was greater for WT KSI than for the mutants, providing a qualitative explanation for the significantly reduced rates of the mutants. The active site exhibited highly restricted motion during the proton transfer reactions, but small conformational changes occurred to facilitate the proton transfer reactions by strengthening the hydrogen-bonding interactions and by bringing the proton donor and acceptor closer to each other with the proper orientation for proton transfer. Thus, these calculations

  15. Impact of proton beam availability on patient treatment schedule in radiation oncology.

    PubMed

    Miller, Eric D; Derenchuk, Vladimir; Das, Indra J; Johnstone, Peter A S

    2012-11-08

    Proton beam therapy offers unique physical properties with potential for reduced toxicity and better patient care. There is an increased interest in radiation oncology centers to acquire proton therapy capabilities. The operation of a proton treatment center is quite different than a photon-based clinic because of the more complex technology involved, as well as the single proton beam source serving multiple treatment rooms with no backup source available. There is limited published data which investigates metrics that can be used to determine the performance of a proton facility. The purpose of this study is to evaluate performance metrics of Indiana University Cyclotron Operations (IUCO), including availability, mean time between failures, and mean time to repair, and to determine how changes in these metrics impact patient treatments. We utilized a computerized maintenance management system to log all downtime occurrences and servicing operations for the facility. These data were then used to calculate the availability as well as the mean time between failures and mean time to repair. Impact on patient treatments was determined by analyzing delayed and missed treatments, which were recorded in an electronic medical record and database maintained by the therapists. The availability of the IUCO proton beam has been increasing since beginning of operation in 2003 and averaged 96.9% for 2009 through 2011. The mean time between failures and mean time to repair were also determined and correlated with improvements in the maintenance and operating procedures of the facility, as well as environmental factors. It was found that events less than 15 minutes in duration have minimal impact on treatment delays, while events lasting longer than one hour may result in missed treatments. The availability of the proton beam was more closely correlated with delayed than with missed treatments, demonstrating the utility and limitations of the availability metric. In conclusion, we

  16. Impact of January 2005 Solar Proton Events on Chlorine Species

    NASA Technical Reports Server (NTRS)

    Damiani, A.; Funke, B.; Marsh, D. R.; Lopez-Puertas, M.; Santee, M. L.; Froidevaux, L.; Wang, S.; Jackman, C. H.; von Clarmann, T.; Gardini, A.; Cordero, R. R.; Storini, M.

    2011-01-01

    Sudden changes in stratospheric chlorine species in the polar northern atmosphere, caused by the Solar Proton Events (SPEs) of 17 and 20 January 2005, have been investigated and compared with version 4 of the Whole Atmosphere Community Climate Model (WACCM4). We used Aura Microwave Limb Sounder (MLS) measurements to monitor the variability of ClO, HCl, HOCl and Michelson Interferometer for Passive Atmospheric Sounder (MIPAS) on ENVISAT to retrieve ClONO2. SPE-induced chlorine activation has been identified. HCl decrease occurred at nearly all the investigated altitudes with the lowest values (of less than 0.25 ppbv) on 21 January. HOCl was found to be the main active chlorine species under nighttime conditions (with increases of more than 0.2 ppbv) whereas both HOCL and CLO enhancements (about 0.1 ppbv) have been observed at the polar night terminator. Further, small ClO decreases (of less than 0.1 ppbv) and ClONO2 enhancements (0.2 ppbv) have been observed at higher latitudes (i.e., at nighttime) roughly above 2hPa. While WACCM4 reproduces most of the SPE-induced variability in the chlorine species fairly well, in some particular regions discrepancies between the modeled and measured temporal evolution of the abundances of chlorine species were found. HOCl changes are modelled very well with respect to both magnitude and geographic distribution. ClO decreases are reproduced at high latitudes, whereas ClO enhancements in the terminator region are underestimated and attributed to background variations. WACCM4 also reproduces the HCl depletion in the mesosphere but it does not show the observed decrease below about 2 hPa. Finally, WACCM4 simulations indicate that the observed ClONO2 increase is dominated by background variability, although SPE-induced production might contribute by 0.1 ppbv.

  17. Impact of January 2005 Solar Proton Events on Chlorine Species

    NASA Technical Reports Server (NTRS)

    Damiani, A.; Funke, B.; Marsh, D. R.; Lopez-Puertas, M.; Santee, M. L.; Froidevaux, L.; Wang, S.; Jackman, C. H.; vonClarmann, T.; Gardini, A.; Cordero, R. R.; Storini, M.

    2012-01-01

    Sudden changes in stratospheric chlorine species in the polar northern atmosphere, caused by the Solar Proton Events (SPEs) of 17 and 20 January 2005, have been investigated and compared with version 4 of the Whole Atmosphere Community Climate Model (WACCM4). We used Aura Microwave Limb Sounder (MLS) measurements to monitor the variability of ClO, HCl, HOCl and Michelson Interferometer for Passive Atmospheric Sounder (MIPAS) on ENVISAT to retrieve ClONO2. SPE-induced chlorine activation has been identified. HCl decrease occurred at nearly all the investigated altitudes (i.e., 10-0.5 hPa) with the strongest decrease (of about 0.25 ppbv) on 21 January. HOCl was found to be the main active chlorine species under nighttime conditions (with increases of more than 0.2 ppbv) whereas both HOCl and ClO enhancements (about 0.1 ppbv) have been observed at the polar night terminator. Further, small ClO decreases (of less than 0.1 ppbv) and ClONO2 enhancements (about 0.2 ppbv) have been observed at higher latitudes (i.e., at nighttime) roughly above 2 hPa. While WACCM4 reproduces most of the SPE-induced variability in the chlorine species fairly well, in some particular regions discrepancies between the modeled and measured temporal evolution of the abundances of chlorine species were found. HOCl changes are modelled very well with respect to both magnitude and geographic distribution. ClO decreases are reproduced at high latitudes, whereas ClO enhancements in the terminator region are underestimated and attributed to background variations. WACCM4 also reproduces the HCl depletion in the mesosphere but it does not show the observed decrease below about 2 hPa. Finally, WACCM4 simulations indicate that the observed ClONO2 increase is dominated by background variability, although SPE-induced production might contribute by 0.1 ppbv.

  18. Impact of the material composition on proton range variation - A Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Wu, S. W.; Tung, C. J.; Lee, C. C.; Fan, K. H.; Huang, H. C.; Chao, T. C.

    2015-11-01

    In this study, we used the Geant4 toolkit to demonstrate the impacts of the material composition of tissues on proton range variation. Bragg curves of different materials subjected to a 250 MeV mono-energy proton beam were simulated and compared. These simulated materials included adipose, heart, brain, cartilage, cortical bone and water. The results showed that there was significant proton range deviation between Bragg curves, especially for cortical bone. The R50 values for a 250 MeV proton beam were approximately 39.55 cm, 35.52 cm, 37.00 cm, 36.51 cm, 36.72 cm, 22.53 cm, and 38.52 cm in the phantoms that were composed completely of adipose, cartilage, tissue, heart, brain, cortical bone, and water, respectively. Mass density and electron density were used to scale the proton range for each material; electron density provided better range scaling. In addition, a similar comparison was performed by artificially setting all material density to 1.0 g/cm3 to evaluate the range deviation due to chemical components alone. Tissue heterogeneity effects due to density variation were more significant, and less significant for chemical composition variation unless the Z/A was very different.

  19. The family impacts of proton radiation therapy for children with brain tumors.

    PubMed

    Houtrow, Amy J; Yock, Torunn I; Delahaye, Jennifer; Kuhlthau, Karen

    2012-01-01

    Children with brain tumors experience significant alterations to their health and well-being due to the tumors themselves and oncologic treatment. Caring for children with brain tumors can have significant impacts on families, especially during and shortly after treatment. In this study of the impacts on families caring for children undergoing proton radiation therapy for brain tumors, the authors found that families experienced a broad array of negative impacts. Families reported feeling like they were living on a roller coaster, feeling that others treated them differently, and having to give up things as a family. In the multivariable linear regression model, older age of the child and higher reported child health-related quality of life were associated with less family impact. The presence of concurrent chemotherapy was associated with increased family impact. This is the first study to specifically evaluate the families of children being treated with proton radiation therapy. The findings in this study are consistent with the findings in other studies of children treated with standard therapy that show that families experience a variety of stressors and negative impacts while their children are receiving treatment. Health care providers should be aware of the potential impacts on families of children with brain tumors and their treatment to provide robust services to meet the health, psychological, and social needs of such children and their families. PMID:22647729

  20. The clinical impact of uncertainties in the mean excitation energy of human tissues during proton therapy

    NASA Astrophysics Data System (ADS)

    Besemer, Abigail; Paganetti, Harald; Bednarz, Bryan

    2013-02-01

    Uncertainties in the estimated mean excitation energies (I-values) needed for calculating proton stopping powers can be in the order of 10-15%, which introduces a fundamental limitation in the accuracy of proton range determination. Previous efforts have quantified shifts in proton depth dose distributions due to I-value uncertainties in water and homogenous tissue phantoms. This study is the first to quantify the clinical impact of I-value uncertainties on proton dose distributions within patient geometries. A previously developed Geant4 based Monte Carlo code was used to simulate a proton treatment plan for three patients (prostate, pancreases, and liver) with varying tissue I-values. A uniform variation study was conducted in which the tissue I-values were varied by ±5% and ±10% of the nominal values as well as a probabilistic variation study in which the I-values were randomly sampled according to a normal distribution with the mean equal to the nominal I-value and a standard deviation of 5 and 10% of the nominal values. Modification of tissue I-values impacted both the proton range and SOBP width. R90 range shifts up to 7.7 mm (4.4.%) and R80 range shifts up to 4.8 mm (1.9%) from the nominal range were recorded. Modulating the tissue I-values by 10% the nominal value resulted in up to a 3.5% difference mean dose in the target volumes and organs at risk compared to the nominal case. The range and dose differences were the largest for the deeper-seated prostate and pancreas cases. The treatments that were simulated with randomly sampled I-values resulted in range and dose differences that were generally within the upper and lower bounds set by the 10% uniform variations. This study demonstrated the impact of I-value uncertainties on patient dose distributions. Clearly, sub-millimeter precision in proton therapy would necessitate a reduction in I-value uncertainties to ensure an efficacious clinical outcome.

  1. Dynamical orientation effects in atomic ionization by impact of protons and positrons

    NASA Astrophysics Data System (ADS)

    Fregenal, Daniel; Barrachina, Raúl; Bernardi, Guillermo; Suárez, Sergio; Fiol, Juan

    2011-10-01

    Recent results in ionization collisions with positrons and protons showed that just above the two-body threshold, for electron velocities close to the final projectile's velocity, the electron-projectile continuum dipole is narrowly oriented along the direction of motion of its centre-of-mass, with the negative charge pointing towards the residual target. Although a forward-backward asymmetry in the vicinity of the two-body threshold has been studied many year ago in ion impact ionization collisions, that was by far a much milder effect that left no fingerprint on the cusp position. Our results show that the phenomena is present for ionization by impact of both protons and positrons. In this communication, through measurements on H+ + He and calculations we analyze in detail this effect that can be linked to a dynamical alignment of the two-body subsystem in the continuum. Recent results in ionization collisions with positrons and protons showed that just above the two-body threshold, for electron velocities close to the final projectile's velocity, the electron-projectile continuum dipole is narrowly oriented along the direction of motion of its centre-of-mass, with the negative charge pointing towards the residual target. Although a forward-backward asymmetry in the vicinity of the two-body threshold has been studied many year ago in ion impact ionization collisions, that was by far a much milder effect that left no fingerprint on the cusp position. Our results show that the phenomena is present for ionization by impact of both protons and positrons. In this communication, through measurements on H+ + He and calculations we analyze in detail this effect that can be linked to a dynamical alignment of the two-body subsystem in the continuum. This work was partially supported by the Consejo Nacional de Investigaciones Cientificas y Tecnicas, Universidad Nacional de Cuyo and Fundacion Balseiro.

  2. CERN antiproton target: Hydrocode analysis of its core material dynamic response under proton beam impact

    NASA Astrophysics Data System (ADS)

    Martin, Claudio Torregrosa; Perillo-Marcone, Antonio; Calviani, Marco; Muñoz-Cobo, José-Luis

    2016-07-01

    Antiprotons are produced at CERN by colliding a 26 GeV /c proton beam with a fixed target made of a 3 mm diameter, 55 mm length iridium core. The inherent characteristics of antiproton production involve extremely high energy depositions inside the target when impacted by each primary proton beam, making it one of the most dynamically demanding among high energy solid targets in the world, with a rise temperature above 2000 °C after each pulse impact and successive dynamic pressure waves of the order of GPa's. An optimized redesign of the current target is foreseen for the next 20 years of operation. As a first step in the design procedure, this numerical study delves into the fundamental phenomena present in the target material core under proton pulse impact and subsequent pressure wave propagation by the use of hydrocodes. Three major phenomena have been identified, (i) the dominance of a high frequency radial wave which produces destructive compressive-to-tensile pressure response (ii) The existence of end-of-pulse tensile waves and its relevance on the overall response (iii) A reduction of 44% in tensile pressure could be obtained by the use of a high density tantalum cladding.

  3. Impact of spot size on plan quality of spot scanning proton radiosurgery for peripheral brain lesions

    SciTech Connect

    Wang, Dongxu Dirksen, Blake; Hyer, Daniel E.; Buatti, John M.; Sheybani, Arshin; Dinges, Eric; Felderman, Nicole; TenNapel, Mindi; Bayouth, John E.; Flynn, Ryan T.

    2014-12-15

    Purpose: To determine the plan quality of proton spot scanning (SS) radiosurgery as a function of spot size (in-air sigma) in comparison to x-ray radiosurgery for treating peripheral brain lesions. Methods: Single-field optimized (SFO) proton SS plans with sigma ranging from 1 to 8 mm, cone-based x-ray radiosurgery (Cone), and x-ray volumetric modulated arc therapy (VMAT) plans were generated for 11 patients. Plans were evaluated using secondary cancer risk and brain necrosis normal tissue complication probability (NTCP). Results: For all patients, secondary cancer is a negligible risk compared to brain necrosis NTCP. Secondary cancer risk was lower in proton SS plans than in photon plans regardless of spot size (p = 0.001). Brain necrosis NTCP increased monotonically from an average of 2.34/100 (range 0.42/100–4.49/100) to 6.05/100 (range 1.38/100–11.6/100) as sigma increased from 1 to 8 mm, compared to the average of 6.01/100 (range 0.82/100–11.5/100) for Cone and 5.22/100 (range 1.37/100–8.00/100) for VMAT. An in-air sigma less than 4.3 mm was required for proton SS plans to reduce NTCP over photon techniques for the cohort of patients studied with statistical significance (p = 0.0186). Proton SS plans with in-air sigma larger than 7.1 mm had significantly greater brain necrosis NTCP than photon techniques (p = 0.0322). Conclusions: For treating peripheral brain lesions—where proton therapy would be expected to have the greatest depth-dose advantage over photon therapy—the lateral penumbra strongly impacts the SS plan quality relative to photon techniques: proton beamlet sigma at patient surface must be small (<7.1 mm for three-beam single-field optimized SS plans) in order to achieve comparable or smaller brain necrosis NTCP relative to photon radiosurgery techniques. Achieving such small in-air sigma values at low energy (<70 MeV) is a major technological challenge in commercially available proton therapy systems.

  4. The kinetic energy spectrum of protons produced by the dissociative ionization of H2 by electron impact

    NASA Technical Reports Server (NTRS)

    Khakoo, M. A.; Srivastava, S. K.

    1985-01-01

    The kinetic energy spectra of protons resulting from the dissociative ionization of H2 by electron impact have been measured for electron impact energies from threshold (approximately 17 eV) to 160 eV at 90 deg and 30 deg detection angles, using a crossed-beam experimental arrangement. To check reliability, two separate proton energy analysis methods have been employed, i.e., a time-of-flight proton energy analysis and an electrostatic hemispherical energy analyzer. The present results are compared with previous measurements.

  5. Angular and energy distributions of electrons produced in arbitrary biomaterials by proton impact.

    PubMed

    de Vera, Pablo; Garcia-Molina, Rafael; Abril, Isabel

    2015-01-01

    We present a simple method for obtaining reliable angular and energy distributions of electrons ejected from arbitrary condensed biomaterials by proton impact. Relying on a suitable description of the electronic excitation spectrum and a physically motivated relation between the ion and electron scattering angles, it yields cross sections in rather good agreement with experimental data in a broad range of ejection angles and energies, by only using as input the target composition and density. The versatility and simplicity of the method, which can be also extended to other charged particles, make it especially suited for obtaining ionization data for any complex biomaterial present in realistic cellular environments.

  6. Angular and Energy Distributions of Electrons Produced in Arbitrary Biomaterials by Proton Impact

    NASA Astrophysics Data System (ADS)

    de Vera, Pablo; Garcia-Molina, Rafael; Abril, Isabel

    2015-01-01

    We present a simple method for obtaining reliable angular and energy distributions of electrons ejected from arbitrary condensed biomaterials by proton impact. Relying on a suitable description of the electronic excitation spectrum and a physically motivated relation between the ion and electron scattering angles, it yields cross sections in rather good agreement with experimental data in a broad range of ejection angles and energies, by only using as input the target composition and density. The versatility and simplicity of the method, which can be also extended to other charged particles, make it especially suited for obtaining ionization data for any complex biomaterial present in realistic cellular environments.

  7. Proton irradiation impacts age-driven modulations of cancer progression influenced by immune system transcriptome modifications from splenic tissue

    PubMed Central

    Wage, Justin; Ma, Lili; Peluso, Michael; Lamont, Clare; Evens, Andrew M.; Hahnfeldt, Philip; Hlatky, Lynn; Beheshti, Afshin

    2015-01-01

    Age plays a crucial role in the interplay between tumor and host, with additional impact due to irradiation. Proton irradiation of tumors induces biological modulations including inhibition of angiogenic and immune factors critical to ‘hallmark’ processes impacting tumor development. Proton irradiation has also provided promising results for proton therapy in cancer due to targeting advantages. Additionally, protons may contribute to the carcinogenesis risk from space travel (due to the high proportion of high-energy protons in space radiation). Through a systems biology approach, we investigated how host tissue (i.e. splenic tissue) of tumor-bearing mice was altered with age, with or without whole-body proton exposure. Transcriptome analysis was performed on splenic tissue from adolescent (68-day) versus old (736-day) C57BL/6 male mice injected with Lewis lung carcinoma cells with or without three fractionations of 0.5 Gy (1-GeV) proton irradiation. Global transcriptome analysis indicated that proton irradiation of adolescent hosts caused significant signaling changes within splenic tissues that support carcinogenesis within the mice, as compared with older subjects. Increases in cell cycling and immunosuppression in irradiated adolescent hosts with CDK2, MCM7, CD74 and RUVBL2 indicated these were the key genes involved in the regulatory changes in the host environment response (i.e. the spleen). Collectively, these results suggest that a significant biological component of proton irradiation is modulated by host age through promotion of carcinogenesis in adolescence and resistance to immunosuppression, carcinogenesis and genetic perturbation associated with advancing age. PMID:26253138

  8. Proton irradiation impacts age-driven modulations of cancer progression influenced by immune system transcriptome modifications from splenic tissue.

    PubMed

    Wage, Justin; Ma, Lili; Peluso, Michael; Lamont, Clare; Evens, Andrew M; Hahnfeldt, Philip; Hlatky, Lynn; Beheshti, Afshin

    2015-09-01

    Age plays a crucial role in the interplay between tumor and host, with additional impact due to irradiation. Proton irradiation of tumors induces biological modulations including inhibition of angiogenic and immune factors critical to 'hallmark' processes impacting tumor development. Proton irradiation has also provided promising results for proton therapy in cancer due to targeting advantages. Additionally, protons may contribute to the carcinogenesis risk from space travel (due to the high proportion of high-energy protons in space radiation). Through a systems biology approach, we investigated how host tissue (i.e. splenic tissue) of tumor-bearing mice was altered with age, with or without whole-body proton exposure. Transcriptome analysis was performed on splenic tissue from adolescent (68-day) versus old (736-day) C57BL/6 male mice injected with Lewis lung carcinoma cells with or without three fractionations of 0.5 Gy (1-GeV) proton irradiation. Global transcriptome analysis indicated that proton irradiation of adolescent hosts caused significant signaling changes within splenic tissues that support carcinogenesis within the mice, as compared with older subjects. Increases in cell cycling and immunosuppression in irradiated adolescent hosts with CDK2, MCM7, CD74 and RUVBL2 indicated these were the key genes involved in the regulatory changes in the host environment response (i.e. the spleen). Collectively, these results suggest that a significant biological component of proton irradiation is modulated by host age through promotion of carcinogenesis in adolescence and resistance to immunosuppression, carcinogenesis and genetic perturbation associated with advancing age.

  9. Assessing the clinical impact of approximations in analytical dose calculations for proton therapy

    PubMed Central

    Schuemann, J.; Giantsoudi, D.; Grassberger, C.; Moteabbed, M.; Min, C.H.; Paganetti, H.

    2015-01-01

    Purpose To assess the impact of approximations in current analytical dose calculation methods (ADCs) on tumor control probability (TCP) in proton therapy. Methods Dose distributions planned with ADC were compared to delivered dose distributions (as determined by Monte Carlo simulations). A total of 50 patients were investigated in this analysis with 10 patients per site for 5 treatment sites (head-and-neck, lung, breast, prostate, liver). Differences were evaluated using dosimetric indices based on a dose-volume-histogram analysis, a γ-index analysis and estimations of TCP. Results We find that ADC overestimates the target doses on average by 1–2% for all patients considered. The mean dose, D95, D50 and D02 (the dose value covering 95%, 50% and 2% of the target volume, respectively) are predicted within 5% of the delivered dose. The γ-index passing rate for target volumes was above 96% for a 3%/3mm criteria. Differences in TCP were up to 2%, 2.5%, 6%, 6.5%, and 11% for liver and breast, prostate, head-and-neck and lung patients, respectively. Differences in normal tissue complication probabilities for bladder and anterior-rectum of prostate patients were less than 3%. Conclusion Our results indicate that current dose calculation algorithms lead to underdosage of the target by as much as 5%, resulting in differences in TCP of up to 11%. In order to ensure full target coverage, advanced dose-calculation methods like Monte Carlo simulations may be necessary in proton therapy. Monte Carlo simulations may also be required in order to avoid biases due to systematic discrepancies in calculated dose distributions for clinical trials comparing proton therapy to conventional radiotherapy. PMID:26025779

  10. Assessing the Clinical Impact of Approximations in Analytical Dose Calculations for Proton Therapy

    SciTech Connect

    Schuemann, Jan Giantsoudi, Drosoula; Grassberger, Clemens; Moteabbed, Maryam; Min, Chul Hee; Paganetti, Harald

    2015-08-01

    Purpose: To assess the impact of approximations in current analytical dose calculation methods (ADCs) on tumor control probability (TCP) in proton therapy. Methods: Dose distributions planned with ADC were compared with delivered dose distributions as determined by Monte Carlo simulations. A total of 50 patients were investigated in this analysis with 10 patients per site for 5 treatment sites (head and neck, lung, breast, prostate, liver). Differences were evaluated using dosimetric indices based on a dose-volume histogram analysis, a γ-index analysis, and estimations of TCP. Results: We found that ADC overestimated the target doses on average by 1% to 2% for all patients considered. The mean dose, D95, D50, and D02 (the dose value covering 95%, 50% and 2% of the target volume, respectively) were predicted within 5% of the delivered dose. The γ-index passing rate for target volumes was above 96% for a 3%/3 mm criterion. Differences in TCP were up to 2%, 2.5%, 6%, 6.5%, and 11% for liver and breast, prostate, head and neck, and lung patients, respectively. Differences in normal tissue complication probabilities for bladder and anterior rectum of prostate patients were less than 3%. Conclusion: Our results indicate that current dose calculation algorithms lead to underdosage of the target by as much as 5%, resulting in differences in TCP of up to 11%. To ensure full target coverage, advanced dose calculation methods like Monte Carlo simulations may be necessary in proton therapy. Monte Carlo simulations may also be required to avoid biases resulting from systematic discrepancies in calculated dose distributions for clinical trials comparing proton therapy with conventional radiation therapy.

  11. The impact of CT scan energy on range calculation in proton therapy planning.

    PubMed

    Grantham, Kevin K; Li, Hua; Zhao, Tianyu; Klein, Eric E

    2015-01-01

    The purpose of this study was to investigate the impact of tube potential (kVp) on the CT number (HU) to proton stopping power ratio (PSPR) conversion. The range and dosimetric change introduced by a mismatch in kVp used for the CT scan and the HU to PSPR table, based on a specific kVp, used to calculate dose are analyzed. Three HU to PSPR curves, corresponding to three kVp settings on the CT scanner, were created. A treatment plan was created for a single beam in a water phantom passing through a wedge-shaped bone heterogeneity. The dose was recalculated by changing only the HU to PSPR table used in the dose calculation. The change in the position of the distal 90% isodose line was recorded as a function of heterogeneity thickness along the beam path. The dosimetric impact of a mismatch in kVp between the CT and the HU to PSPR table was investigated by repeating this procedure for five clinical plans comparing DVH data and dose difference distributions. The HU to PSPR tables diverge for CT numbers greater than 200 HU. In the phantom plan, the divergence of the tables resulted in a difference in range of 1.6 mm per cm of bone in the beam path, for the HU used. For the clinical plans, the dosimetric effect of a kVp mismatch depends on the amount of bone in the beam path and the proximity of OARs to the distal range of the planned beams. A mismatch in kVp between the CT and the HU to PSPR table can introduce inaccuracy in the proton beam range. For dense bone, the measured range difference was approximately 1.6 mm per cm of bone along the beam path. However, the clinical cases analyzed showed a range change of 1 mm or less. Caution is merited when such a mismatch may occur. PMID:26699561

  12. The impact of active site protonation on substrate ring conformation in Melanocarpus albomyces cellobiohydrolase Cel7B.

    PubMed

    Schutt, Timothy C; Bharadwaj, Vivek S; Granum, David M; Maupin, C Mark

    2015-07-14

    The ability to utilize biomass as a feedstock for liquid fuel and value-added chemicals is dependent on the efficient and economic utilization of lignin, hemicellulose, and cellulose. In current bioreactors, cellulases are used to convert crystalline and amorphous cellulose to smaller oligomers and eventually glucose by means of cellulase enzymes. A critical component of the enzyme catalyzed hydrolysis reaction is the degree to which the enzyme can facilitate substrate ring deformation from the chair to a more catalytically active conformation (e.g. skewed boat) at the -1 subsite. Presented here is an evaluation of the impact of the protonation state for critical active site residues (i.e. Glu212, Asp214, Glu217, and His228) in Melanocarpus albomyces (Ma) Cellobiohydrolase Cel7B on the substrate's orientation and ring conformation. It is found that the protonation state of the active site can disrupt the intra-enzyme hydrogen bonding network and enhance the sampling of various ring puckering conformations for the substrate ring at the +1 and -1 subsites. In particular it is observed that the protonation state of Asp214 dictates the accessibility of the glycosidic bond to the catalytic acid/base Glu217 by influencing the φ/ψ dihedral angles and the puckering of the ring structure. The protonation-orientation-conformation analysis has revealed an active site that primarily utilizes two highly coupled protonation schemes; one protonation scheme to orient the substrate and generate catalytically favorable substrate geometries and ring puckering conformations and another protonation scheme to hydrolyze the glycosidic bond. In addition to identifying how enzymes utilize protonation state to manipulate substrate geometry, this study identifies possible directions for improving catalytic activity through protein engineering. PMID:26061383

  13. Impact of x-ray dose on the CR-39 response to 1-9 MeV protons with application to proton spectroscopy at OMEGA and NIF

    NASA Astrophysics Data System (ADS)

    Rojas-Herrera, J.; Rinderknecht, H. G.; Gatu Johnson, M.; Zylstra, A.; Rosenberg, M.; Sio, H.

    2014-10-01

    CR-39 is a clear plastic nuclear track detector utilized in many nuclear diagnostics fielded in large-scale inertial confinement fusion (ICF) facilities. Large x-ray fluences in ICF experiments may impact the CR-39 response to incident charged particles. A thick-target bremsstrahlung x-ray machine was used to expose CR-39 to various x-ray doses to determine their impact on the CR-39 response to protons. This x-ray machine emits Cu- α line-radiation at 8 keV and has been absolutely calibrated using radiochromic film. The CR-39 detectors were then exposed to D3He-protons generated by the MIT Linear Electrostatic Ion Accelerator. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those not exposed to x-rays. For example, a dose of 60 +/- 1.3 Gy results in a decrease of 53% in the track diameter, while a dose of 5 +/- 0.1 Gy causes a decrease of 7.5% in the track diameter. Doses of approximately 5Gy are typical on CR-39 detectors used to diagnose ICF implosions at OMEGA and the NIF. The resulting data will be used to evaluate how x-ray doses received by CR-39 in OMEGA and NIF experiments affect the recorded data. This undergraduate research was supported in part by the U.S. DOE, NLUF, LLE, and LLNL.

  14. Impact of the January 2012 solar proton event on polar mesospheric clouds

    NASA Astrophysics Data System (ADS)

    Bardeen, C. G.; Marsh, D. R.; Jackman, C. H.; Hervig, M. E.; Randall, C. E.

    2016-08-01

    We use data from the Aeronomy of Ice in the Mesosphere mission and simulations using the Whole Atmosphere Community Climate Model to determine the impact of the 23-30 January 2012 solar proton event (SPE) on polar mesospheric clouds (PMCs) and mesospheric water vapor. We see a small heating and loss of ice mass on 26 January that is consistent with prior results but is not statistically significant. We also find a previously unreported but statistically significant ~10% increase in ice mass and in water vapor in the sublimation area in the model that occurs in the 7 to 14 days following the start of the event. The magnitude of the response to the January 2012 SPE is small compared to other sources of variability like gravity waves and planetary waves; however, sensitivity tests suggest that with larger SPEs this delayed increase in ice mass will increase, while there is little change in the loss of ice mass early in the event. The PMC response to SPEs in models is dependent on the gravity wave parameterization, and temperature anomalies from SPEs may be useful in evaluating and tuning gravity wave parameterizations.

  15. Impact of Intrafraction and Residual Interfraction Effect on Prostate Proton Pencil Beam Scanning

    SciTech Connect

    Tang, Shikui; Deville, Curtiland; Tochner, Zelig; Wang, Ken Kang-Hsin; McDonough, James; Vapiwala, Neha; Both, Stefan

    2014-12-01

    Purpose: To quantitatively evaluate the impact of interplay effect and plan robustness associated with intrafraction and residual interfraction prostate motion for pencil beam scanning proton therapy. Methods and Materials: Ten prostate cancer patients with weekly verification CTs underwent pencil beam scanning with the bilateral single-field uniform dose (SFUD) modality. A typical field had 10-15 energy layers and 500-1000 spots. According to their treatment logs, each layer delivery time was <1 s, with average time to change layers of approximately 8 s. Real-time intrafraction prostate motion was determined from our previously reported prospective study using Calypso beacon transponders. Prostate motion and beam delivering sequence of the worst-case scenario patient were synchronized to calculate the “true” dose received by the prostate. The intrafraction effect was examined by applying the worst-case scenario prostate motion on the planning CT, and the residual interfraction effect was examined on the basis of weekly CT scans. The resultant dose variation of target and critical structures was examined to evaluate the interplay effect. Results: The clinical target volume (CTV) coverage was degraded because of both effects. The CTV D{sub 99} (percentage dose to 99% of the CTV) varied up to 10% relative to the initial plan in individual fractions. However, over the entire course of treatment the total dose degradation of D{sub 99} was 2%-3%, with a standard deviation of <2%. Absolute differences between SFUD, intensity modulate proton therapy, and one-field-per-day SFUD plans were small. The intrafraction effect dominated over the residual interfraction effect for CTV coverage. Mean dose to the anterior rectal wall increased approximately 10% because of combined residual interfraction and intrafraction effects, the interfraction effect being dominant. Conclusions: Both intrafraction and residual interfraction prostate motion degrade CTV coverage within a

  16. Impact of Various Beam Parameters on Lateral Scattering in Proton and Carbon-ion Therapy

    PubMed Central

    Ebrahimi Loushab, M.; Mowlavi, A.A.; Hadizadeh, M.H.; Izadi, R.; Jia, S.B.

    2015-01-01

    Background In radiation therapy with ion beams, lateral distributions of absorbed dose in the tissue are important. Heavy ion therapy, such as carbon-ion therapy, is a novel technique of high-precision external radiotherapy which has advantages over proton therapy in terms of dose locality and biological effectiveness. Methods In this study, we used Monte Carlo method-based Geant4 toolkit to simulate and calculate the effects of energy, shape and type of ion beams incident upon water on multiple scattering processes. Nuclear reactions have been taken into account in our calculation. A verification of this approach by comparing experimental data and Monte Carlo methods will be presented in an upcoming paper. Results Increasing particle energies, the width of the Bragg curve becomes larger but with increasing mass of particles, the width of the Bragg curve decreases. This is one of the advantages of carbon-ion therapy to treat with proton. The transverse scattering of dose distribution is increased with energy at the end of heavy ion beam range. It can also be seen that the amount of the dose scattering for carbon-ion beam is less than that of proton beam, up to about 160mm depth in water. Conclusion The distortion of Bragg peak profiles, due to lateral scattering of carbon-ion, is less than proton. Although carbon-ions are primarily scattered less than protons, the corresponding dose distributions, especially the lateral dose, are not much less. PMID:26688795

  17. Dataset showing the impact of the protonation states on molecular dynamics of HIV protease.

    PubMed

    Soares, Rosemberg O; Torres, Pedro H M; da Silva, Manuela L; Pascutti, Pedro G

    2016-09-01

    The data described here supports the research article "Unraveling HIV Protease Flaps Dynamics by Constant pH Molecular Dynamics Simulations" (Soares et al., 2016) [1]. The data involves both standard Molecular Dynamics (MD) and Constant pH Molecular Dynamics (CpHMD) to elucidate the effect of protonation states of catalytic dyad on the HIV-PR conformation. The data obtained from MD simulation demonstrate that the protonation state of the two aspartic acids (Asp25/Asp25') has a strong influence on the dynamics of the HIV-PR. Regarding the CpHMD simulation, we performed pka calculations for HIV-PR and the data indicate that only one catalytic aspartate should be protonated. PMID:27536715

  18. Pressure-induced amorphization of a dense coordination polymer and its impact on proton conductivity

    SciTech Connect

    Umeyama, Daiki; Hagi, Keisuke; Ogiwara, Naoki; Horike, Satoshi E-mail: kitagawa@icems.kyoto-u.ac.jp; Tassel, Cedric; Kageyama, Hiroshi; Higo, Yuji; Kitagawa, Susumu E-mail: kitagawa@icems.kyoto-u.ac.jp

    2014-12-01

    The proton conductivity of a dense coordination polymer (CP) was investigated under high-pressure conditions. Impedance measurements under high pressures revealed that the proton conductivity of the CP decreased more than 1000-fold at pressures of 3–7 GPa and that the activation energy for proton conduction almost doubled compared with that at ambient pressure. A synchrotron X-ray study under high pressure identified the amorphization process of the CP during compression, which rationally explains the decrease in conductivity and increase in activation energy. This phenomenon is categorized as reversible pressure-induced amorphization of a dense CP and is regarded as a demonstration of the coupling of the mechanical and electrical properties of a CP.

  19. SU-E-T-523: On the Radiobiological Impact of Lateral Scatter in Proton Beams

    SciTech Connect

    Heuvel, F Van den; Deruysscher, D

    2014-06-01

    Introduction: In proton therapy, justified concern has been voiced with respect to an increased efficiency in cell kill at the distal end of the Bragg peak. This coupled with range uncertainty is a counter indication to use the Bragg peak to define the border of a treated volume with a critical organ. An alternative is to use the lateral edge of the proton beam, obtaining more robust plans. We investigate the spectral and biological effects of the lateral scatter . Methods: A general purpose Monte Carlo simulation engine (MCNPX 2.7c) installed on a Scientific Linux cluster, calculated the dose deposition spectrum of protons, knock on electrons and generated neutrons for a proton beam with maximal kinetic energy of 200MeV. Around the beam at different positions in the beam direction the spectrum is calculated in concentric rings of thickness 1cm. The deposited dose is converted to a double strand break map using an analytical expression.based on micro dosimetric calculations using a phenomenological Monte Carlo code (MCDS). A strict version of RBE is defined as the ratio of generation of double strand breaks in the different modalities. To generate the reference a Varian linac was modelled in MCNPX and the generated electron dose deposition spectrum was used . Results: On a pristine point source 200MeV beam the RBE before the Bragg peak was of the order of 1.1, increasing to 1.7 right behind the Bragg peak. When using a physically more realistic beam of 10cm diameter the effect was smaller. Both the lateral dose and RBE increased with increasing beam depth, generating a dose deposition with mixed biological effect. Conclusions: The dose deposition in proton beams need to be carefully examined because the biological effect will be different depending on the treatment geometry. Deeply penetrating proton beams generate more biologically effective lateral scatter.

  20. Dosimetric impact of intrafraction motion for compensator-based proton therapy of lung cancer

    NASA Astrophysics Data System (ADS)

    Zhao, Li; Sandison, George A.; Farr, Jonathan B.; Chien Hsi, Wen; Li, X. Allen

    2008-06-01

    Compensator-based proton therapy of lung cancer using an un-gated treatment while allowing the patient to breathe freely requires a compensator design that ensures tumor coverage throughout respiration. Our investigation had two purposes: one is to investigate the dosimetric impact when a composite compensator correction is applied, or is not, and the other one is to evaluate the significance of using different respiratory phases as the reference computed tomography (CT) for treatment planning dose calculations. A 4D-CT-based phantom study and a real patient treatment planning study were performed. A 3D MIP dataset generated over all phases of the acquired 4D-CT scans was adopted to design the field-specific composite aperture and compensator. In the phantom study, the MIP-based compensator design plan named plan D was compared to the other three plans, in which average intensity projection (AIP) images in conjunction with the composite target volume contour copied from the MIP images were used. Relative electron densities within the target envelope were assigned either to original values from the AIP image dataset (plan A) or to predetermined values, 0.8 (plan B) and 0.9 (plan C). In the patient study, the dosimetric impact of a compensator design based on the MIP images (plan ITVMIP) was compared to designs based on end-of-inhale (EOI) (plan ITVEOI) and middle-of-exhale (MOE) CT images (plan ITVMOE). The dose distributions were recalculated for each phase. Throughout the ten phases, it shows that DGTVmin changed slightly from 86% to 89% (SD = 0.9%) of prescribed dose (PD) in the MIP plan, while varying greatly from 10% to 79% (SD = 26.7%) in plan A, 17% to 73% (SD = 22.5%) in plan B and 53% to 73% (SD = 6.8%) in plan C. The same trend was observed for DGTVmean and V95 with less amplitude. In the MIP-based plan ITVMIP, DGTVmean was almost identically equal to 95% in each phase (SD = 0.5%). The patient study verified that the MIP approach increased the minimum

  1. Dosimetric impact of intrafraction motion for compensator-based proton therapy of lung cancer.

    PubMed

    Zhao, Li; Sandison, George A; Farr, Jonathan B; Hsi, Wen Chien; Li, X Allen

    2008-06-21

    Compensator-based proton therapy of lung cancer using an un-gated treatment while allowing the patient to breathe freely requires a compensator design that ensures tumor coverage throughout respiration. Our investigation had two purposes: one is to investigate the dosimetric impact when a composite compensator correction is applied, or is not, and the other one is to evaluate the significance of using different respiratory phases as the reference computed tomography (CT) for treatment planning dose calculations. A 4D-CT-based phantom study and a real patient treatment planning study were performed. A 3D MIP dataset generated over all phases of the acquired 4D-CT scans was adopted to design the field-specific composite aperture and compensator. In the phantom study, the MIP-based compensator design plan named plan D was compared to the other three plans, in which average intensity projection (AIP) images in conjunction with the composite target volume contour copied from the MIP images were used. Relative electron densities within the target envelope were assigned either to original values from the AIP image dataset (plan A) or to predetermined values, 0.8 (plan B) and 0.9 (plan C). In the patient study, the dosimetric impact of a compensator design based on the MIP images (plan ITV(MIP)) was compared to designs based on end-of-inhale (EOI) (plan ITV(EOI)) and middle-of-exhale (MOE) CT images (plan ITV(MOE)). The dose distributions were recalculated for each phase. Throughout the ten phases, it shows that D(GTV)(min) changed slightly from 86% to 89% (SD = 0.9%) of prescribed dose (PD) in the MIP plan, while varying greatly from 10% to 79% (SD = 26.7%) in plan A, 17% to 73% (SD = 22.5%) in plan B and 53% to 73% (SD = 6.8%) in plan C. The same trend was observed for D(GTV)(mean) and V95 with less amplitude. In the MIP-based plan ITV(MIP), D(GTV)(mean) was almost identically equal to 95% in each phase (SD = 0.5%). The patient study verified that the MIP approach

  2. The creation, destruction, and transfer of multipole moments in electron- and proton-impact ionization of atoms and ions

    NASA Astrophysics Data System (ADS)

    Csanak, G.; Inal, M. K.; Fontes, C. J.; Kilcrease, D. P.

    2013-12-01

    Expanding on previous works that involved elastic and inelastic scattering of electrons by atoms and ions, we use the wave-packet propagation scheme of Dollard to define multipole moment creation, destruction and transfer cross sections for electron- and proton-impact ionization of atoms and ions. The electron-impact cross sections can then be used by defining appropriate rate coefficients for use in Fujimoto’s population-alignment collisional-radiative model for cylindrically symmetric plasmas. Our result for the alignment creation cross section is in agreement with those formulae that were obtained earlier intuitively or by semi-classical collisional methods. The multipole cross sections obtained here can be used also for modelling the relaxation behaviour of laser-excited plasmas under cylindrical symmetry conditions. We have also derived the electron- and proton-impact ionization multipole cross sections in terms of Liouville-space quantities, which then enabled us by using group theoretical methods to obtain the azimuthal-angle dependence of the multipole cross sections and symmetry properties that are results of reflection across a plane over the collisional axis.

  3. Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics.

    PubMed

    Rinderknecht, H G; Rojas-Herrera, J; Zylstra, A B; Frenje, J A; Gatu Johnson, M; Sio, H; Sinenian, N; Rosenberg, M J; Li, C K; Séguin, F H; Petrasso, R D; Filkins, T; Steidle, Jeffrey A; Steidle, Jessica A; Traynor, N; Freeman, C

    2015-12-01

    The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1-100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protons with energies in the range 0.5-9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. The impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant. PMID:26724031

  4. Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

    SciTech Connect

    Rinderknecht, H. G. Rojas-Herrera, J.; Zylstra, A. B.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Sinenian, N.; Rosenberg, M. J.; Li, C. K.; Séguin, F. H.; Petrasso, R. D.; Filkins, T.; Steidle, Jessica A.; Traynor, N.; Freeman, C.; Steidle, Jeffrey A.

    2015-12-15

    The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protons with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. The impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.

  5. Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

    SciTech Connect

    Rinderknecht, H. G.; Rojas-Herrera, J.; Zylstra, A. B.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Sinenian, N.; Rosenberg, M. J.; Li, C. K.; Seguin, F. H.; Petrasso, R. D.; Filkins, T.; Steidle, Jeffrey A.; Steidle, Jessica A.; Traynor, N.; Freeman, C.

    2015-12-23

    The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protons with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. Lastly, the impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.

  6. Impact of Energetically Accessible Proton Permutations in the Spectroscopy and Dynamics of H{_5^+}

    NASA Astrophysics Data System (ADS)

    Lin, Zhou; McCoy, Anne B.

    2016-06-01

    H{_5^+} has been proposed to be the intermediate of the astrochemically interesting proton transfer reaction H_3^+ + H_2 → H_2 + H_3^+. The scrambling of five protons in this floppy, ``structureless'' ion introduces complications to its high-resolution rovibrational spectroscopy and the proton transfer dynamics between H{_3^+} and H_2. Quantum chemical studies are performed to predict and interpret the spectroscopic and dynamical properties of H{_5^+}, with special consideration paid to the group theoretical aspects. If the full permutation of protons were allowed in H{_5^+}, just like in CH{_5^+}, the system should have been characterized by the G240 complete permutation-inversion group. However, our diffusion Monte Carlo calculations indicate that such a full permutation is not allowed for most of the molecular configurations sampled by the reaction path of the proton transfer process in question, and the energetically accessible permutations are functions of the distance between the H{_3^+} and H_2 fragments. In the present study, we investigate two extreme geometries of H{_5^+}, the [H_2-H-H_2]^+ shared-proton intermediate and the H_3^+\\cdots H_2 long-range complex, using two subgroups of G240, G16 and G24, respectively. In these two limiting circumstances, we derive the symmetry-adapted basis functions for the energy levels that describe the nuclear spins and the rovibrational motions of H{_5^+}. Based on the results of these derivations, we discuss the spectroscopic properties of H{_5^+}, including the coupling between different rovibrational degrees of freedom in the effective nuclear motion Hamiltonian, the electric-dipole selection rules for rovibrational spectroscopy, and correlations of energy levels between [H_2-H-H_2]^+ and H_3^+\\cdots H_2. Our study can be considered as the first step towards the implementation of future quantitative theoretical investigations for comparison with spectroscopic and dynamical experiments. X.-G. Wang and T

  7. SU-E-CAMPUS-J-06: The Impact of CT-Scan Energy On Range Uncertainty in Proton Therapy Planning

    SciTech Connect

    Grantham, K; Li, H; Zhao, T; Klein, E

    2014-06-15

    Purpose: To investigate the impact of tube potential (kVp) on the CTnumber (HU) to proton stopping power ratio (PSPR) conversion table; the range uncertainty and the dosimetric change introduced by a mismatch in kVp between the CT and the HU to PSPR table used to calculate dose are analyzed. Methods: A CIRS CT-ED phantom was scanned with a Philips Brilliance 64-slice scanner under 90kVp and 120kVp tube potentials. Two HU to PSPR curves were then created. Using Eclipse (Varian) a treatment plan was created for a single beam in a water phantom (HU=0) passing through a wedge-shaped heterogeneity (HU=1488). The dose was recalculated by changing only the HU to PSPR table used in the dose calculation. The change in range (the distal 90% isodose line) relative to a distal structure was recorded as a function of heterogeneity thickness in the beam. To show the dosimetric impact of a mismatch in kVp between the CT and the HU to PSPR table, we repeated this procedure using a clinical plan comparing DVH data. Results: The HU to PSPR tables diverge for low-density bone and higher density structures. In the phantom plan, the divergence of the tables results in a change in range of ~1mm per cm of bone in the beam path for the HU used. For the clinical plan, a mismatch in kVp showed a 28% increase in mean dose to the brainstem along with a 10% increase in maximum dose to the brainstem center. Conclusion: A mismatch in kVp between the CT and the HU to PSPR table can introduce significant uncertainty in the proton beam range. For dense bone, the measured range uncertainty is about 1mm per cm of bone in the beam. CT-scan energy verification should be employed, particularly when high-density media is in the proton beam path.

  8. The impact of proton pump inhibitors on the human gastrointestinal microbiome.

    PubMed

    Freedberg, Daniel E; Lebwohl, Benjamin; Abrams, Julian A

    2014-12-01

    Potent gastric acid suppression using proton pump inhibitors (PPIs) is common in clinical practice but may have important effects on human health that are mediated through changes in the gastrointestinal microbiome. In the esophagus, PPIs change the normal bacterial milieu to decrease distal esophageal exposure to inflammatory gram-negative bacteria. In the stomach, PPIs alter the abundance and location of gastric Helicobacter pylori and other bacteria. In the small bowel, PPIs cause polymicrobial small bowel bacterial overgrowth and have been associated with the diagnosis of celiac disease. In the colon, PPIs associate with incident but not recurrent Clostridium difficile infection.

  9. Proton Therapy

    MedlinePlus

    ... nucleus is surrounded by electrons. In proton therapy, beams of fast-moving protons are used to destroy ... atoms to release proton, neutron, and helium ion beams. In this highly specialized form of radiosurgery , proton ...

  10. Relativistic electron- and proton-impact ionization of highly stripped heavy ions determined from projectile-electron loss in H[sub 2] and He

    SciTech Connect

    Feinberg, B.; Gould, H.; Meyerhof, W.E.; Belkacem, A.; Huelskoetter, H.; Alonso, J.R.; Blumenfeld, L.; Dillard, E.; Guardala, N.; Krebs, G.F.; McMahan, M.A.; Rhoades-Brown, M.J.; Rude, B.S.; Schweppe, J.; Spooner, D.W.; Street, K.; Thieberger, P.; Wegner, H. Chemical Sciences Division, Lawrence Berkeley Laboratory, MS 71-259, One Cyclotron Road, Berkeley, California 94720 Department of Physics, Stanford University, Stanford, California 94305 Accelerator Development Department, Brookhaven National Laboratory, Upton, New York 11973 Berkeley High School, Berkeley, California 94704 Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 )

    1993-03-01

    We show that electron- and proton-impact ionization cross sections for highly stripped heavy ions can be deduced from the projectile-electron-loss cross sections determined by collisions with a H[sub 2] and a He target. We measure electron loss for 100- and 380-MeV/u Au[sup 52+], and 405-MeV/u U[sup 86+] in H[sub 2] and He targets, and extract the electron- and proton-impact ionization cross sections. Our results are compared with calculations and with channeling experiments.

  11. Dosimetric impact of a CT metal artefact suppression algorithm for proton, electron and photon therapies.

    PubMed

    Wei, Jikun; Sandison, George A; Hsi, Wen-Chien; Ringor, Michael; Lu, Xiaoyi

    2006-10-21

    Accurate dose calculation is essential to precision radiation treatment planning and this accuracy depends upon anatomic and tissue electron density information. Modern treatment planning inhomogeneity corrections use x-ray CT images and calibrated scales of tissue CT number to electron density to provide this information. The presence of metal in the volume scanned by an x-ray CT scanner causes metal induced image artefacts that influence CT numbers and thereby introduce errors in the radiation dose distribution calculated. This paper investigates the dosimetric improvement achieved by a previously proposed x-ray CT metal artefact suppression technique when the suppressed images of a patient with bilateral hip prostheses are used in commercial treatment planning systems for proton, electron or photon therapies. For all these beam types, this clinical image and treatment planning study reveals that the target may be severely underdosed if a metal artefact-contaminated image is used for dose calculations instead of the artefact suppressed one. Of the three beam types studied, the metal artefact suppression is most important for proton therapy dose calculations, intermediate for electron therapy and least important for x-ray therapy but still significant. The study of a water phantom having a metal rod simulating a hip prosthesis indicates that CT numbers generated after image processing for metal artefact suppression are accurate and thus dose calculations based on the metal artefact suppressed images will be of high fidelity.

  12. Space Weather impact on the degradation of NOAA POES MEPED proton detectors

    NASA Astrophysics Data System (ADS)

    Ødegaard, Linn-Kristine Glesnes; Tyssøy, Hilde Nesse; Jakobsen Sandanger, Marit Irene; Stadsnes, Johan; Søraas, Finn

    2016-06-01

    The Medium Energy Proton and Electron Detector (MEPED) on board the National Oceanic and Atmospheric Administration Polar Orbiting Environmental Satellites (NOAA POES) is known to degrade with time. In recent years a lot of effort has been put into calibrating the degraded proton detectors. We make use of previous work and show that the degradation of the detectors can be attributed to the radiation dose of each individual instrument. However, the effectiveness of the radiation in degrading the detector is modulated when it is weighted by the mean ap index, increasing the degradation rate in periods with high geomagnetic activity, and decreasing it through periods of low activity. When taking ap and the radiation dose into account, we find that the degradation rate is independent of spacecraft and detector pointing direction. We have developed a model to estimate the correction factor for all the MEPED detectors as a function of accumulated corrected flux and the ap index. We apply the routine to NOAA POES spacecraft starting with NOAA-15, including the European satellites MetOp-02 and MetOp-01, and estimate correction factors.

  13. Evaluating the potential impact of proton carriers on syntrophic propionate oxidation

    PubMed Central

    Juste-Poinapen, Natacha M. S.; Turner, Mark S.; Rabaey, Korneel; Virdis, Bernardino; Batstone, Damien J.

    2015-01-01

    Anaerobic propionic acid degradation relies on interspecies electron transfer (IET) between propionate oxidisers and electron acceptor microorganisms, via either molecular hydrogen, formate or direct transfers. We evaluated the possibility of stimulating direct IET, hence enhancing propionate oxidation, by increasing availability of proton carriers to decrease solution resistance and reduce pH gradients. Phosphate was used as a proton carrying anion, and chloride as control ion together with potassium as counter ion. Propionic acid consumption in anaerobic granules was assessed in a square factorial design with ratios (1:0, 2:1, 1:1, 1:2 and 0:1) of total phosphate (TP) to Cl−, at 1X, 10X, and 30X native conductivity (1.5 mS.cm−1). Maximum specific uptake rate, half saturation, and time delay were estimated using model-based analysis. Community profiles were analysed by fluorescent in situ hybridisation and 16S rRNA gene pyrosequencing. The strongest performance was at balanced (1:1) ratios at 10X conductivity where presumptive propionate oxidisers namely Syntrophobacter and Candidatus Cloacamonas were more abundant. There was a shift from Methanobacteriales at high phosphate, to Methanosaeta at low TP:Cl ratios and low conductivity. A lack of response to TP, and low percentage of presumptive electroactive organisms suggested that DIET was not favoured under the current experimental conditions. PMID:26670292

  14. Evaluating the potential impact of proton carriers on syntrophic propionate oxidation

    NASA Astrophysics Data System (ADS)

    Juste-Poinapen, Natacha M. S.; Turner, Mark S.; Rabaey, Korneel; Virdis, Bernardino; Batstone, Damien J.

    2015-12-01

    Anaerobic propionic acid degradation relies on interspecies electron transfer (IET) between propionate oxidisers and electron acceptor microorganisms, via either molecular hydrogen, formate or direct transfers. We evaluated the possibility of stimulating direct IET, hence enhancing propionate oxidation, by increasing availability of proton carriers to decrease solution resistance and reduce pH gradients. Phosphate was used as a proton carrying anion, and chloride as control ion together with potassium as counter ion. Propionic acid consumption in anaerobic granules was assessed in a square factorial design with ratios (1:0, 2:1, 1:1, 1:2 and 0:1) of total phosphate (TP) to Cl-, at 1X, 10X, and 30X native conductivity (1.5 mS.cm-1). Maximum specific uptake rate, half saturation, and time delay were estimated using model-based analysis. Community profiles were analysed by fluorescent in situ hybridisation and 16S rRNA gene pyrosequencing. The strongest performance was at balanced (1:1) ratios at 10X conductivity where presumptive propionate oxidisers namely Syntrophobacter and Candidatus Cloacamonas were more abundant. There was a shift from Methanobacteriales at high phosphate, to Methanosaeta at low TP:Cl ratios and low conductivity. A lack of response to TP, and low percentage of presumptive electroactive organisms suggested that DIET was not favoured under the current experimental conditions.

  15. Impact of x-ray dose on track formation and data analysis for CR-39-based proton diagnostics

    DOE PAGES

    Rinderknecht, H. G.; Rojas-Herrera, J.; Zylstra, A. B.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Sinenian, N.; Rosenberg, M. J.; Li, C. K.; Seguin, F. H.; et al

    2015-12-23

    The nuclear track detector CR-39 is used extensively for charged particle diagnosis, in particular proton spectroscopy, at inertial confinement fusion facilities. These detectors can absorb x-ray doses from the experiments in the order of 1–100 Gy, the effects of which are not accounted for in the previous detector calibrations. X-ray dose absorbed in the CR-39 has previously been shown to affect the track size of alpha particles in the detector, primarily due to a measured reduction in the material bulk etch rate [Rojas-Herrera et al., Rev. Sci. Instrum. 86, 033501 (2015)]. Similar to the previous findings for alpha particles, protonsmore » with energies in the range 0.5–9.1 MeV are shown to produce tracks that are systematically smaller as a function of the absorbed x-ray dose in the CR-39. The reduction of track size due to x-ray dose is found to diminish with time between exposure and etching if the CR-39 is stored at ambient temperature, and complete recovery is observed after two weeks. Lastly, the impact of this effect on the analysis of data from existing CR-39-based proton diagnostics on OMEGA and the National Ignition Facility is evaluated and best practices are proposed for cases in which the effect of x rays is significant.« less

  16. Analysis of photon emission from 50--350-keV proton impact on H{sub 2}O

    SciTech Connect

    Goldman, Benjamin D.; Timpone, Stephanie A.; Monce, Michael N.; Mitchell, Laurel; Griffin, Brian

    2011-04-15

    We have measured photon emission cross sections from neutral fragments produced by collisions of 50-350 keV protons with H{sub 2}O molecules. Balmer {alpha}-{delta} emissions from both the target and projectile were recorded. We also analyzed A {sup 2}{Sigma}{sup +}-X {sup 2}{Pi} (0,0) and (1,0) emission from the excited OH fragment produced during target dissociation. Trends in the cross sections revealed two key properties of the collision process: (1) The Bethe theory accurately describes target emission from both H and OH fragments and (2) the ratio of any two Balmer emission cross sections for both the target and projectile can be approximated by simple functions of the respective optical oscillator strengths. Finally, we provide the Bethe fit parameters necessary to calculate the target emission cross sections at all nonrelativistic impact energies.

  17. The impact of the intrinsic charm quark content of a proton on the differential \\gamma +c cross section

    NASA Astrophysics Data System (ADS)

    Rostami, S.; Khorramian, A.; Aleedaneshvar, A.

    2016-06-01

    We present a comparative analysis of the impact of the non-perturbative intrinsic charm quark content of a proton on the differential cross section of a γ + c-jet in pp and p\\bar{p} collisions, for the kinematic regions that are sensitive to this contribution. We discuss the Q 2 evolution of intrinsic quark distributions at the next-to-leading order (NLO) and present a code which provides these distributions as a function of x and Q 2 for any arbitrary Fock state probability. For the p\\bar{p} collisions at the Tevatron, the results are compared with recent experimental data at \\sqrt{s}=1.96 TeV and also predictions for pp collisions at \\sqrt{s}=8 TeV and \\sqrt{s}=13 TeV for the Large Hadron Collider.

  18. Dosimetric impact of number of treatment fields in uniform scanning proton therapy planning of lung cancer.

    PubMed

    Rana, Suresh; Simpson, Hilarie; Larson, Gary; Zheng, Yuanshui

    2014-10-01

    The main purpose of this study was to perform a treatment planning study for lung cancer comparing 2-field (2F) versus 3-field (3F) techniques in uniform scanning proton therapy (USPT). Ten clinically approved lung cancer treatment plans delivered using USPT at our proton center were included in this retrospective study. All 10 lung cases included 4D computed tomography (CT) simulation. The delineation of target volumes was done based on the maximum intensity projection (MIP) images. Both the 3F and 2F treatment plans were generated for the total dose of 74 cobalt-gray-equivalent (CGE) with a daily dose of 2 CGE. 3F plan was generated by adding an extra beam in the 2F plan. Various dosimetric parameters between 2F and 3F plans were evaluated. 3F plans produced better target coverage and conformality as well as lower mean dose to the lung, with absolute difference between 3F and 2F plans within 2%. In contrast, the addition of third beam led to increase of low-dose regions (V20 and V5) in the lung in 3F plans compared to the ones in 2F plans with absolute difference within 2%. Maximum dose to the spinal cord was lower in 2F plans. Mean dose to the heart and esophagus were comparable in both 3F and 2F plans. In conclusion, the 3F technique in USPT produced better target coverage and conformality, but increased the low-dose regions in the lung when compared to 2F technique.

  19. Dosimetric impact of number of treatment fields in uniform scanning proton therapy planning of lung cancer

    PubMed Central

    Rana, Suresh; Simpson, Hilarie; Larson, Gary; Zheng, Yuanshui

    2014-01-01

    The main purpose of this study was to perform a treatment planning study for lung cancer comparing 2-field (2F) versus 3-field (3F) techniques in uniform scanning proton therapy (USPT). Ten clinically approved lung cancer treatment plans delivered using USPT at our proton center were included in this retrospective study. All 10 lung cases included 4D computed tomography (CT) simulation. The delineation of target volumes was done based on the maximum intensity projection (MIP) images. Both the 3F and 2F treatment plans were generated for the total dose of 74 cobalt-gray-equivalent (CGE) with a daily dose of 2 CGE. 3F plan was generated by adding an extra beam in the 2F plan. Various dosimetric parameters between 2F and 3F plans were evaluated. 3F plans produced better target coverage and conformality as well as lower mean dose to the lung, with absolute difference between 3F and 2F plans within 2%. In contrast, the addition of third beam led to increase of low-dose regions (V20 and V5) in the lung in 3F plans compared to the ones in 2F plans with absolute difference within 2%. Maximum dose to the spinal cord was lower in 2F plans. Mean dose to the heart and esophagus were comparable in both 3F and 2F plans. In conclusion, the 3F technique in USPT produced better target coverage and conformality, but increased the low-dose regions in the lung when compared to 2F technique. PMID:25525308

  20. SU-E-T-201: Impact of Gantry and Table Angles On Proton Range in XiO Treatment Planning System

    SciTech Connect

    Rana, S; Zheng, Y

    2014-06-01

    Purpose: To investigate if the selection of gantry and table angle has an impact on the calculated proton range (defined at the 90% distal falloff of the spread out Bragg peak) in XiO treatment planning system (TPS). Methods: A homogenous water phantom (40x40x40 cm{sup 3}) was constructed in XiO TPS. Ten treatment plans were generated using identical beam conditions (proton range = 25cm, modulation = 10cm) and device (10 cm diameter aperture) for various combinations of gantry (G) and table (T) angles (G0T90, G90T90, G180T90, G270T90, G90T0, G90T180, G90T270, G270T0, G270T180, and G270T270). The isocenter in each plan was selected at the center of the cubic target volume (5x5x5 cm{sup 3}) inside the phantom. All ten plans were calculated with pencil beam algorithm using a grid size of 3mm. The calculated proton ranges in all 10 plans were then compared against the prescribed (or expected) proton range, which was 25 cm in this study. Results: For all 10 treatment plans, calculated proton range was smaller when compared to the expected value (25cm), with XiO predicting the proton range from 24.62cm to 24.92cm. The difference between the prescribed and calculated proton range was highest (3.8mm) for plans with G90T270 and G270T90. Conclusion: Treatment plans generated in XiO TPS using G90T270 and G270T90 could produce a difference of more than 3 mm between the prescribed and calculated proton ranges. Further study using smaller dose calculation grid size (e.g., 1mm) is under progress to determine if the dose calculation grid size has any impact on the proton range. What causes the angle dependence of proton range calculation with the XiO TPS is also under investigation.

  1. Proton pump inhibitors--their pharmacological impact on the clinical management of acid-related disorders.

    PubMed

    Klotz, Ulrich

    2009-01-01

    Acid secretion or intragastric pH play a very important role in the pathophysiology of acid-related disorders such as peptic ulcer (PU), gastrooesophageal reflux disease (GERD) or nonsteroidal anti-inflammatory drug (NSAID)-induced gastrointestinal lesions. Proton pump inhibitors (PPIs) represent the most potent/effective antisecretory drugs for these indications. For the selection among the various agents (omeprazole/esomeprazole (CAS 73590-58-6/119141-88-7), pantoprazole (CAS 102625-70-7), lansoprazole (CAS103577-45-3), rabeprazole (CAS 117976-83-3)) some features of their pharmacokinetic (PK) and pharmacodynamic (PD) properties should be considered as the clinical outcome depends on systemic drug exposure (PK) and elevation of intragastric pH about certain threshold levels (PD). The present review updates PK, PD and clinical data to provide some guidance between the PPIs which differ somewhat in their metabolic pattern and drug interaction potential. Based on 24-h intragastric pH assessments the relative potencies of the PPIs compared to omeprazole were in healthy volunteers (in GERD patients): 0.42 (0.59), 1.0 (0.8), 1.0 (1.0), 1.25 (1.25) and 2.0 (1.4) for pantoprazole, lansoprazole, omeprazole, esomeprazole and rabeprazole, respectively. In general, the clinical benefits of PPI are well documented but some patients can be regarded as non-responders and thus represent a challenge for future clinical research. PMID:19634508

  2. Impact of heat and water management on proton exchange membrane fuel cells degradation in automotive application

    NASA Astrophysics Data System (ADS)

    Nandjou, F.; Poirot-Crouvezier, J.-P.; Chandesris, M.; Blachot, J.-F.; Bonnaud, C.; Bultel, Y.

    2016-09-01

    In Proton Exchange Membrane Fuel Cells, local temperature is a driving force for many degradation mechanisms such as hygrothermal deformation and creep of the membrane, platinum dissolution and bipolar plates corrosion. In order to investigate and quantify those effects in automotive application, durability testing is conducted in this work. During the ageing tests, the local performance and temperature are investigated using in situ measurements of a printed circuit board. At the end of life, post-mortem analyses of the aged components are conducted. The experimental results are compared with the simulated temperature and humidity in the cell obtained from a pseudo-3D multiphysics model in order to correlate the observed degradations to the local conditions inside the stack. The primary cause of failure in automotive cycling is pinhole/crack formation in the membrane, induced by high variations of its water content over time. It is also observed that water condensation largely increases the probability of the bipolar plates corrosion while evaporation phenomena induce local deposits in the cell.

  3. [Impact of Brownian motion and magnetic fields of erythrocytes on spin echo signal of blood protons].

    PubMed

    Zhernovoĭ, A I; Belorukova, M G; Nikolaeva, M N; Sharshina, L M

    2001-01-01

    A reduction in blood So2 and ESR is shown to lead to the decay of a spin echo signal. This effect is explained by the impact of red blood cell magnetic field fluctuations caused by the Brownian motion. The authors propose to use the effect to monitor red blood cell agglutination.

  4. Proton transfer in organic scaffolds

    NASA Astrophysics Data System (ADS)

    Basak, Dipankar

    This dissertation focuses on the fundamental understanding of the proton transfer process and translating the knowledge into design/development of new organic materials for efficient non-aqueous proton transport. For example, what controls the shuttling of a proton between two basic sites? a) Distance between two groups? or b) the basicity? c) What is the impact of protonation on molecular conformation when the basic sites are attached to rigid scaffolds? For this purpose, we developed several tunable proton sponges and studied proton transfer in these scaffolds theoretically as well as experimentally. Next we moved our attention to understand long-range proton conduction or proton transport. We introduced liquid crystalline (LC) proton conductor based on triphenylene molecule and established that activation energy barrier for proton transport is lower in the LC phase compared to the crystalline phase. Furthermore, we investigated the impact of several critical factors: the choice of the proton transferring groups, mobility of the charge carriers, intrinsic vs. extrinsic charge carrier concentrations and the molecular architectures on long-range proton transport. The outcome of this research will lead to a deeper understanding of non-aqueous proton transfer process and aid the design of next generation proton exchange membrane (PEM) for fuel cell.

  5. Fully differential study of wave packet scattering in ionization of helium by proton impact

    NASA Astrophysics Data System (ADS)

    Arthanayaka, T.; Lamichhane, B. R.; Hasan, A.; Gurung, S.; Remolina, J.; Borbély, S.; Járai-Szabó, F.; Nagy, L.; Schulz, M.

    2016-07-01

    We present a fully differential study of projectile coherence effects in ionization in p + He collisions. The experimental data are qualitatively reproduced by a non-perturbative ab initio time-dependent model, which treats the projectile coherence properties in terms of a wave packet. A comparison between first- and higher-order treatments shows that the observed interference structures are primarily due to a coherent superposition of different impact parameters leading to the same scattering angle. Higher-order contributions have a significant effect on the interference term.

  6. Brightness measurement of an electron impact gas ion source for proton beam writing applications

    NASA Astrophysics Data System (ADS)

    Liu, N.; Xu, X.; Pang, R.; Santhana Raman, P.; Khursheed, A.; van Kan, J. A.

    2016-02-01

    We are developing a high brightness nano-aperture electron impact gas ion source, which can create ion beams from a miniature ionization chamber with relatively small virtual source sizes, typically around 100 nm. A prototype source of this kind was designed and successively micro-fabricated using integrated circuit technology. Experiments to measure source brightness were performed inside a field emission scanning electron microscope. The total output current was measured to be between 200 and 300 pA. The highest estimated reduced brightness was found to be comparable to the injecting focused electron beam reduced brightness. This translates into an ion reduced brightness that is significantly better than that of conventional radio frequency ion sources, currently used in single-ended MeV accelerators.

  7. Proton therapy

    MedlinePlus

    ... direction of the tumor. A machine called a synchrotron or cyclotron creates and speeds up the protons. ... redness in the radiation area, and temporary hair loss. AFTER THE PROCEDURE Following proton therapy, you should ...

  8. Enantioselective Protonation

    PubMed Central

    Mohr, Justin T.; Hong, Allen Y.; Stoltz, Brian M.

    2010-01-01

    Enantioselective protonation is a common process in biosynthetic sequences. The decarboxylase and esterase enzymes that effect this valuable transformation are able to control both the steric environment around the proton acceptor (typically an enolate) and the proton donor (typically a thiol). Recently, several chemical methods to achieve enantioselective protonation have been developed by exploiting various means of enantiocontrol in different mechanisms. These laboratory transformations have proven useful for the preparation of a number of valuable organic compounds. PMID:20428461

  9. Long-term Measurements of Solar Proton Fluxes (1963-present) and the Subsequent Impact on Stratospheric Constituents

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; Fleming, Eric L.

    2005-01-01

    The fluxes of solar protons have been measured by satellites for over forty years (1963-present). Eight Interplanetary Monitoring Platform (IMP) satellites measured solar proton fluxes from 1963-1993 and five NOAA Geostationary Operational Environmental Satellites (GOES) were used for the period 1994present. These high energy solar protons precipitate on the Earth's polar atmosphere sporadically, especially during solar proton events (SPEs), which typically last a few days. Solar protons with energies greater than 30 MeV are capable of reaching the stratosphere and causing increases in odd hydrogen (HOx) and odd nitrogen (NOy) constituents at polar latitudes (greater than 60 degrees geomagnetic). The enhanced HOx leads to short-lived ozone depletion (-days) due to the short lifetime of HOx constituents. The enhanced NOy leads to long-lived ozone changes because of the long lifetime of the NOy family in the stratosphere. Several very large SPEs (August 1972, August and October 1989, July and November 2000, September and November 2001, and October 2003) over the 1963-2004 time period were simulated in the GSFC two-dimensional chemistry and transport model and were predicted to cause significant polar upper stratospheric ozone depletion greater than 10%, which lasted for several weeks past the events. Several satellite instruments (BUV, SBUV, SBW/2, SAGE II, HALOE, etc.) have shown constituent changes as a result of SPEs. Long-term (greater than 40 year) model simulations of the influence of the solar protons and satellite measurements during and after some of the very large SPEs will be shown.

  10. The Impact of Intrinsic Heavy Quark Distributions in the Proton on New Physics Searches at the High Intensity Frontier

    SciTech Connect

    Brodsky, Stanley; Gardner, Susan; /Kentucky U.

    2012-02-16

    The possibility of an intense proton facility, at 'Project X' or elsewhere, will provide many new opportunities for searches for physics beyond the Standard Model. A Project X can serve a yet broader role in the search for new physics, and in this note we highlight the manner in which thus-enabled studies of the flavor structure of the proton, particularly of its intrinsic heavy quark content, facilitate other direct and indirect searches for new physics. Intrinsic heavy quarks in both light and heavy hadrons play a key role in searches for physics BSM with hadrons - and their study at the Intensity Frontier may prove crucial to establishing its existence.

  11. Formation of 2-propanol in condensed molecular films of acetaldehyde following electron impact ionisation-induced proton transfer*

    NASA Astrophysics Data System (ADS)

    Borrmann, Tobias; Swiderek, Petra

    2016-06-01

    Experimental studies on thin condensed layers of acetaldehyde have previously revealed that electron exposure at an energy above the ionisation threshold leads to formation of 2-propanol. However, the mechanism of this reaction remained unclear. Therefore, a computational approach is used to explore the electron-induced reactions of acetaldehyde yielding 2-propanol. Starting from hydrogen-bonded dimers of acetaldehyde we show that the initial ionisation event triggers proton transfer between the two acetaldehyde moieties resulting in a hydrogen-bonded complex of a [OCCH3] radical and a protonated acetaldehyde cation. Given an excess energy of up to 0.75 eV and a favourable arrangement, a methyl radical released upon dissociation of the CC bond within the [OCCH3] radical can migrate to the carbonyl carbon of the protonated acetaldehyde cation. This produces a 2-propanol radical cation and CO. Neutral 2-propanol is then obtained by recombination with a second electron. A mechanism involving ionisation-driven proton transfer is thus proposed as pathway to the formation of 2-propanol during electron exposure of condensed layers of acetaldehyde.

  12. Proton Therapy

    NASA Astrophysics Data System (ADS)

    Oelfke, Uwe

    Proton therapy is one of the most rapidly developing new treatment technologies in radiation oncology. This treatment approach has — after roughly 40 years of technical developments — reached a mature state that allows a widespread clinical application. We therefore review the basic physical and radio-biological properties of proton beams. The main physical aspect is the elemental dose distribution arising from an infinitely narrow proton pencil beam. This includes the physics of proton stopping powers and the concept of CSDA range. Furthermore, the process of multiple Coulomb scattering is discussed for the lateral dose distribution. Next, the basic terms for the description of radio-biological properties of proton beams like LET and RBE are briefly introduced. Finally, the main concepts of modern proton dose delivery concepts are introduced before the standard method of inverse treatment planning for hadron therapy is presented.

  13. Proton pencil beam scanning for mediastinal lymphoma: the impact of interplay between target motion and beam scanning.

    PubMed

    Zeng, C; Plastaras, J P; Tochner, Z A; White, B M; Hill-Kayser, C E; Hahn, S M; Both, S

    2015-04-01

    The purpose of this study was to assess the feasibility of proton pencil beam scanning (PBS) for the treatment of mediastinal lymphoma. A group of 7 patients of varying tumor size (100-800 cc) were planned using a PBS anterior field. We investigated 17 fractions of 1.8 Gy(RBE) to deliver 30.6 Gy(RBE) to the internal target volume (ITV). Spots with σ ranging from 4 mm to 8 mm were used for all patients, while larger spots (σ = 6-16 mm) were employed for patients with motion perpendicular to the beam (⩾5 mm), based on initial 4-dimensional computed tomography (4D CT) motion evaluation. We considered volumetric repainting such that the same field would be delivered twice in each fraction. The ratio of extreme inhalation amplitude and regular tidal inhalation amplitude (free-breathing variability) was quantified as an indicator of potential irregular breathing during the scanning. Four-dimensional dose was calculated on the 4D CT scans based on the respiratory trace and beam delivery sequence, implemented by partitioning the spots into separate plans on each 4D CT phase. Four starting phases (end of inhalation, end of exhalation, middle of inhalation and middle of exhalation) were sampled for each painting and 4 energy switching times (0.5 s, 1 s, 3 s and 5 s) were tested, which resulted in 896 dose distributions for the analyzed cohort. Plan robustness was measured for the target and critical structures in terms of the percent difference between 'delivered' dose (4D-evaluated) and planned dose (calculated on average CT). It was found that none of the patients exhibited highly variable or chaotic breathing patterns. For all patients, the ITV D98% was degraded by <2% (standard deviations ∼ 0.1%) when averaged over the whole treatment course. For six out of seven patients, the average degradation of ITV D98% per fraction was within 5% . For one patient with motion perpendicular to the beam (⩾5 mm), the degradation of ITV D98% per fraction was up

  14. Proton pencil beam scanning for mediastinal lymphoma: the impact of interplay between target motion and beam scanning

    NASA Astrophysics Data System (ADS)

    Zeng, C.; Plastaras, J. P.; Tochner, Z. A.; White, B. M.; Hill-Kayser, C. E.; Hahn, S. M.; Both, S.

    2015-04-01

    The purpose of this study was to assess the feasibility of proton pencil beam scanning (PBS) for the treatment of mediastinal lymphoma. A group of 7 patients of varying tumor size (100-800 cc) were planned using a PBS anterior field. We investigated 17 fractions of 1.8 Gy(RBE) to deliver 30.6 Gy(RBE) to the internal target volume (ITV). Spots with σ ranging from 4 mm to 8 mm were used for all patients, while larger spots (σ = 6-16 mm) were employed for patients with motion perpendicular to the beam (⩾5 mm), based on initial 4-dimensional computed tomography (4D CT) motion evaluation. We considered volumetric repainting such that the same field would be delivered twice in each fraction. The ratio of extreme inhalation amplitude and regular tidal inhalation amplitude (free-breathing variability) was quantified as an indicator of potential irregular breathing during the scanning. Four-dimensional dose was calculated on the 4D CT scans based on the respiratory trace and beam delivery sequence, implemented by partitioning the spots into separate plans on each 4D CT phase. Four starting phases (end of inhalation, end of exhalation, middle of inhalation and middle of exhalation) were sampled for each painting and 4 energy switching times (0.5 s, 1 s, 3 s and 5 s) were tested, which resulted in 896 dose distributions for the analyzed cohort. Plan robustness was measured for the target and critical structures in terms of the percent difference between ‘delivered’ dose (4D-evaluated) and planned dose (calculated on average CT). It was found that none of the patients exhibited highly variable or chaotic breathing patterns. For all patients, the ITV D98% was degraded by <2% (standard deviations ˜ 0.1%) when averaged over the whole treatment course. For six out of seven patients, the average degradation of ITV D98% per fraction was within 5% . For one patient with motion perpendicular to the beam (⩾5 mm), the degradation of ITV D98% per fraction was up to 15%, which

  15. Evaluation of the dosimetric impact of interfractional anatomical variations on prostate proton therapy using daily in-room CT images

    SciTech Connect

    Wang, Yi; Efstathiou, Jason A.; Sharp, Gregory C.; Lu, Hsiao-Ming; Trofimov, Alexei V.; Frank Ciernik, I.

    2011-08-15

    Purpose: To quantify interfractional anatomical variations and their dosimetric impact during the course of fractionated proton therapy (PT) of prostate cancer and to assess the robustness of the current treatment planning techniques. Methods: Simulation and daily in-room CT scans from ten prostate carcinoma patients were analyzed. PT treatment plans (78 Gy in 39 fractions of 2 Gy) were created on the simulation CT, delivering 25 fractions to PTV1 (expanded from prostate and seminal vesicles), followed by 14 boost fractions to PTV2 (expanded from prostate). Plans were subsequently applied to daily CT, with beams aligned to the prostate center in the sagittal plane. For five patients having a sufficiently large daily imaging volume, structure contours were manually drawn, and plans were evaluated for all CT sets. For the other five patients, the plans were evaluated for six selected fractions. The daily CT was matched to the simulation CT through deformable registration. The registration accuracy was validated for each fraction, and the three patients with a large number of accurately registered fractions were used for dose accumulation. Results: In individual fractions, the coverage of the prostate, seminal vesicles, and PTV1 was generally maintained at the corresponding prescription dose. For PTV2, the volume covered by the fractional prescription dose of 2 Gy (i.e., V2) was, on average, reduced by less than 3% compared to the simulation plan. Among the 225 (39 x 5 + 6 x 5) fractions examined, 15 showed a V2 reduction larger than 5%, of which ten were caused by a large variation in rectal gas, and five were due to a prostate shift in the craniocaudal direction. The fractional dose to the anterior rectal wall was found to increase for one patient who had large rectal gas volume in 25 of the 39 fractions, and another who experienced significant prostate volume reduction during the treatment. The fractional bladder dose generally increased with decreasing fullness

  16. Proton pencil beam scanning for mediastinal lymphoma: the impact of interplay between target motion and beam scanning.

    PubMed

    Zeng, C; Plastaras, J P; Tochner, Z A; White, B M; Hill-Kayser, C E; Hahn, S M; Both, S

    2015-04-01

    The purpose of this study was to assess the feasibility of proton pencil beam scanning (PBS) for the treatment of mediastinal lymphoma. A group of 7 patients of varying tumor size (100-800 cc) were planned using a PBS anterior field. We investigated 17 fractions of 1.8 Gy(RBE) to deliver 30.6 Gy(RBE) to the internal target volume (ITV). Spots with σ ranging from 4 mm to 8 mm were used for all patients, while larger spots (σ = 6-16 mm) were employed for patients with motion perpendicular to the beam (⩾5 mm), based on initial 4-dimensional computed tomography (4D CT) motion evaluation. We considered volumetric repainting such that the same field would be delivered twice in each fraction. The ratio of extreme inhalation amplitude and regular tidal inhalation amplitude (free-breathing variability) was quantified as an indicator of potential irregular breathing during the scanning. Four-dimensional dose was calculated on the 4D CT scans based on the respiratory trace and beam delivery sequence, implemented by partitioning the spots into separate plans on each 4D CT phase. Four starting phases (end of inhalation, end of exhalation, middle of inhalation and middle of exhalation) were sampled for each painting and 4 energy switching times (0.5 s, 1 s, 3 s and 5 s) were tested, which resulted in 896 dose distributions for the analyzed cohort. Plan robustness was measured for the target and critical structures in terms of the percent difference between 'delivered' dose (4D-evaluated) and planned dose (calculated on average CT). It was found that none of the patients exhibited highly variable or chaotic breathing patterns. For all patients, the ITV D98% was degraded by <2% (standard deviations ∼ 0.1%) when averaged over the whole treatment course. For six out of seven patients, the average degradation of ITV D98% per fraction was within 5% . For one patient with motion perpendicular to the beam (⩾5 mm), the degradation of ITV D98% per fraction was up

  17. Phenomenological treatments of cross-sections for proton and hydrogen impact below 1 keV on molecular nitrogen

    NASA Technical Reports Server (NTRS)

    Porter, H. S.; Green, A. E. S.; Szydlik, P. P.

    1975-01-01

    An analytic independent-particle model is used to construct static potentials to describe the interaction of hydrogen-like ions with atoms and molecules. Parameters of the ion-atom potential are determined from ab initio total energy minimization procedure. The elastic scattering of He(+) from Ne and Ar is investigated as a test case and comparison is made with experiment. The model is then used in conjunction with low energy H(+)-N2 experimental data to construct differential and total cross-sections for the scattering of protons and hydrogen in the energy range of 10 eV to 1 keV from molecular nitrogen. Analytic forms are used to parametrize these cross-sections to facilitate their use in the calculation of energy deposition by protons and hydrogen atoms in atmospheric gases.

  18. Nuclear contribution into single-event upset in 3D on-board electronics at moderate energy cosmic proton impact

    NASA Astrophysics Data System (ADS)

    Chechenin, N. G.; Chuvilskaya, T. V.; Shirokova, A. A.

    2016-05-01

    In continuation and development of our previous works where nuclear reactions of moderate energy (10 - 400 MeV) protons with Si, Al and W have been investigated, the results of reactions with Cu are reported in this paper. Cu is a most important component in composition of materials in contact pads and pathways of modern and perspective ultra large-scale integration circuitry, especially in 3D topology.

  19. Proton Transport

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    The transport of protons across membranes is an essential process for both bioenergetics of modern cells and the origins of cellular life. All living systems make use of proton gradients across cell walls to convert environmental energy into a high-energy chemical compound, adenosine triphosphate (ATP), synthesized from adenosine diphosphate. ATP, in turn, is used as a source of energy to drive many cellular reactions. The ubiquity of this process in biology suggests that even the earliest cellular systems were relying on proton gradient for harvesting environmental energy needed to support their survival and growth. In contemporary cells, proton transfer is assisted by large, complex proteins embedded in membranes. The issue addressed in this Study was: how the same process can be accomplished with the aid of similar but much simpler molecules that could have existed in the protobiological milieu? The model system used in the study contained a bilayer membrane made of phospholipid, dimyristoylphosphatidylcholine (DMPC) which is a good model of the biological membranes forming cellular boundaries. Both sides of the bilayer were surrounded by water which simulated the environment inside and outside the cell. Embedded in the membrane was a fragment of the Influenza-A M$_2$ protein and enough sodium counterions to maintain system neutrality. This protein has been shown to exhibit remarkably high rates of proton transport and, therefore, is an excellent model to study the formation of proton gradients across membranes. The Influenza M$_2$ protein is 97 amino acids in length, but a fragment 25 amino acids long. which contains a transmembrane domain of 19 amino acids flanked by three amino acids on each side. is sufficient to transport protons. Four identical protein fragments, each folded into a helix, aggregate to form small channels spanning the membrane. Protons are conducted through a narrow pore in the middle of the channel in response to applied voltage. This

  20. Proton interrogation

    SciTech Connect

    Morris, Christopher L

    2008-01-01

    Energetic proton beams may provide an attractive alternative when compared to electromagnetic and neutron beams for active interrogation of nuclear threats because: they have large fission cross sections, long mean free paths and high penetration, and proton beams can be manipulated with magnetic optics. We have measured time-dependent cross sections for delayed neutrons and gamma-rays using the 800 MeV proton beam from the Los Alamos Neutron Science Center for a set of bare and shielded targets. The results show significant signals from both unshielded and shielded nuclear materials. Results will be presented.

  1. Proton-impact ionization cross sections of adenine measured at 0.5 and 2.0 MeV by electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Iriki, Y.; Kikuchi, Y.; Imai, M.; Itoh, A.

    2011-11-01

    Double-differential ionization cross sections (DDCSs) of vapor-phase adenine molecules (C5H5N5) by 0.5- and 2.0-MeV proton impact have been measured by the electron spectroscopy method. Electrons ejected from adenine were analyzed by a 45∘ parallel-plate electrostatic spectrometer over an energy range of 1.0-1000 eV at emission angles from 15∘ to 165∘. Single-differential cross sections (SDCSs) and total ionization cross sections (TICSs) were also deduced. It was found from the Platzman plot, defined as SDCSs divided by the classical Rutherford knock-on cross sections per target electron, that the SDCSs at higher electron energies are proportional to the total number of valence electrons (50) of adenine, while those at low-energy electrons are highly enhanced due to dipole and higher-order interactions. The present results of TICS are in fairly good agreement with recent classical trajectory Monte Carlo calculations, and moreover, a simple analytical formula gives nearly equivalent cross sections in magnitude at the incident proton energies investigated.

  2. Proton-impact ionization cross sections of adenine measured at 0.5 and 2.0 MeV by electron spectroscopy

    SciTech Connect

    Iriki, Y.; Kikuchi, Y.; Imai, M.; Itoh, A.

    2011-11-15

    Double-differential ionization cross sections (DDCSs) of vapor-phase adenine molecules (C{sub 5}H{sub 5}N{sub 5}) by 0.5- and 2.0-MeV proton impact have been measured by the electron spectroscopy method. Electrons ejected from adenine were analyzed by a 45 Degree-Sign parallel-plate electrostatic spectrometer over an energy range of 1.0-1000 eV at emission angles from 15 Degree-Sign to 165 Degree-Sign . Single-differential cross sections (SDCSs) and total ionization cross sections (TICSs) were also deduced. It was found from the Platzman plot, defined as SDCSs divided by the classical Rutherford knock-on cross sections per target electron, that the SDCSs at higher electron energies are proportional to the total number of valence electrons (50) of adenine, while those at low-energy electrons are highly enhanced due to dipole and higher-order interactions. The present results of TICS are in fairly good agreement with recent classical trajectory Monte Carlo calculations, and moreover, a simple analytical formula gives nearly equivalent cross sections in magnitude at the incident proton energies investigated.

  3. Elastic, charge transfer, and related transport cross sections for proton impact of atomic hydrogen for astrophysical and laboratory plasma modeling

    NASA Astrophysics Data System (ADS)

    Schultz, D. R.; Ovchinnikov, S. Yu; Stancil, P. C.; Zaman, T.

    2016-04-01

    Updating and extending previous work (Krstić and Schultz 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3458 and other references) comprehensive calculations were performed for elastic scattering and charge transfer in proton—atomic hydrogen collisions. The results, obtained for 1301 collision energies in the center-of-mass energy range of 10-4-104 eV, are provided for integral and differential cross sections relevant to transport modeling in astrophysical and other plasma environments, and are made available through a website. Use of the data is demonstrated through a Monte Carlo transport simulation of solar wind proton propagation through atomic hydrogen gas representing a simple model of the solar wind interaction with heliospheric neutrals.

  4. Elastic, charge transfer, and related transport cross sections for proton impact of atomic hydrogen for astrophysical and laboratory plasma modeling

    NASA Astrophysics Data System (ADS)

    Schultz, D. R.; Ovchinnikov, S. Yu; Stancil, P. C.; Zaman, T.

    2016-04-01

    Updating and extending previous work (Krstić and Schultz 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3458 and other references) comprehensive calculations were performed for elastic scattering and charge transfer in proton—atomic hydrogen collisions. The results, obtained for 1301 collision energies in the center-of-mass energy range of 10‑4–104 eV, are provided for integral and differential cross sections relevant to transport modeling in astrophysical and other plasma environments, and are made available through a website. Use of the data is demonstrated through a Monte Carlo transport simulation of solar wind proton propagation through atomic hydrogen gas representing a simple model of the solar wind interaction with heliospheric neutrals.

  5. High Temperature Protonic Conductors

    NASA Technical Reports Server (NTRS)

    Dynys, Fred; Berger, Marie-Helen; Sayir, Ali

    2007-01-01

    High Temperature Protonic Conductors (HTPC) with the perovskite structure are envisioned for electrochemical membrane applications such as H2 separation, H2 sensors and fuel cells. Successive membrane commercialization is dependent upon addressing issues with H2 permeation rate and environmental stability with CO2 and H2O. HTPC membranes are conventionally fabricated by solid-state sintering. Grain boundaries and the presence of intergranular second phases reduce the proton mobility by orders of magnitude than the bulk crystalline grain. To enhanced protonic mobility, alternative processing routes were evaluated. A laser melt modulation (LMM) process was utilized to fabricate bulk samples, while pulsed laser deposition (PLD) was utilized to fabricate thin film membranes . Sr3Ca(1+x)Nb(2-x)O9 and SrCe(1-x)Y(x)O3 bulk samples were fabricated by LMM. Thin film BaCe(0.85)Y(0.15)O3 membranes were fabricated by PLD on porous substrates. Electron microscopy with chemical mapping was done to characterize the resultant microstructures. High temperature protonic conduction was measured by impedance spectroscopy in wet air or H2 environments. The results demonstrate the advantage of thin film membranes to thick membranes but also reveal the negative impact of defects or nanoscale domains on protonic conductivity.

  6. Impact of Long-Term Proton Pump Inhibitor Therapy on Gut Microbiota in F344 Rats: Pilot Study

    PubMed Central

    Shin, Cheol Min; Kim, Nayoung; Kim, Yong Sung; Nam, Ryoung Hee; Park, Ji Hyun; Lee, Dong Ho; Seok, Yeong-Jae; Kim, Yeon-Ran; Kim, Joo-Hyon; Kim, Jung Min; Kim, Joo Sung; Jung, Hyun Chae

    2016-01-01

    Background/Aims To evaluate changes in gut microbiota composition following long-term proton pump inhibitor (PPI) treatment. Methods Twenty-four-week-old F344 rats were fed diets with (n=6) or without (n=5) lansoprazole for 50 weeks. Profiles of luminal microbiota in the terminal ileum were then analyzed. Pyrosequencing of the 16S rRNA gene was performed using an FLX genome sequencer (454 Life Sciences/Roche). Results Rats treated with lansoprazole showed significantly reduced body weights compared to controls (lansoprazole-treated rats and controls, 322.3±15.3 g vs 403.2±5.2 g, respectively, p<0.001). However, stool frequencies and consistencies did not differ between the two groups. The composition of the gut microbiota in lansoprazole-treated rats was quite different from that of the controls. In the controls, the microbiota profiles obtained from the terminal ileum showed a predominance of Proteobacteria (93.9%) due to the abundance of Escherichia and Pasteurella genera. Conversely, lansoprazole-treated rats showed an elevated population of Firmicutes (66.9%), which was attributed to an increased ratio of Clostridium g4 to Lactobacillus genera. Conclusions This preliminary study suggests that long-term administration of PPI may cause weight loss and changes to the microbiota in the terminal ileum. PMID:27458177

  7. SU-E-T-296: Single Field Per Day Vs. Multiple Fields Per Day and the Impact On BED in Proton Therapy Treatment

    SciTech Connect

    Grantham, K; Wooten, H; Zhao, T; Klein, E

    2014-06-01

    Purpose: A common practice, in proton therapy, is to deliver a rotating subset of fields from the treatment plan for the daily fractions. This study compares the impact this practice has on the biological effective dose (BED) versus delivering all planned fields daily. Methods: For two scenarios (a phantom with a geometry approximating the anatomy of a prostate treatment with opposing lateral beams, and a clinical 3-field brain treatment), treatment plans were produced in Eclipse (Varian) to simulate delivery of one, two, and three fields per fraction. The RT-Dose file, structure set, and α/β ratios were processed using in-house MATLAB code to return a new RT-Dose file containing the BED (including a proton RBE of 1.1) which was imported back into Eclipse for analysis. Results: For targets and regions of field overlap in the treatment plan, BED is not affected by delivery regimen. In the phantom, BED in the femoral heads showed increased by 20% when a single field was used rather than two fields. In the brain treatment, the minimum BED to the left optic nerve and the pituitary gland increased by 13% and 10% respectively, for a one-field regime compared to three-fields per fraction. Comparing the two-field and threefield regimes, the optic nerve BED was not significantly affected and the minimum pituitary BED was 4% higher for two fields per day. Conclusion: Hypo-fractionation effects, in regions of non-overlap of fields, significantly increase the BED to the involved tissues by as much as 20%. Care should be taken to avoid inadvertently sacrificing plan effectiveness in the interest of reduced treatment time.

  8. Intensity modulated proton therapy treatment planning using single-field optimization: The impact of monitor unit constraints on plan quality

    SciTech Connect

    Zhu, X. R.; Sahoo, N.; Zhang, X.; Robertson, D.; Li, H.; Choi, S.; Lee, A. K.; Gillin, M. T.

    2010-03-15

    Purpose: To investigate the effect of monitor unit (MU) constraints on the dose distribution created by intensity modulated proton therapy (IMPT) treatment planning using single-field optimization (SFO). Methods: Ninety-four energies between 72.5 and 221.8 MeV are available for scanning beam IMPT delivery at our institution. The minimum and maximum MUs for delivering each pencil beam (spot) are 0.005 and 0.04, respectively. These MU constraints are not considered during optimization by the treatment planning system; spots are converted to deliverable MUs during postprocessing. Treatment plans for delivering uniform doses to rectangular volumes with and without MU constraints were generated for different target doses, spot spacings, spread-out Bragg peak (SOBP) widths, and ranges in a homogeneous phantom. Four prostate cancer patients were planned with and without MU constraints using different spot spacings. Rounding errors were analyzed using an in-house software tool. Results: From the phantom study, the authors have found that both the number of spots that have rounding errors and the magnitude of the distortion of the dose distribution from the ideally optimized distribution increases as the field dose, spot spacing, and range decrease and as the SOBP width increases. From our study of patient plans, it is clear that as the spot spacing decreases the rounding error increases, and the dose coverage of the target volume becomes unacceptable for very small spot spacings. Conclusions: Constraints on deliverable MU for each spot could create a significant distortion from the ideally optimized dose distributions for IMPT fields using SFO. To eliminate this problem, the treatment planning system should incorporate the MU constraints in the optimization process and the delivery system should reliably delivery smaller minimum MUs.

  9. The Proton

    NASA Astrophysics Data System (ADS)

    Canal, Carlos Garcia; Sassot, Rodolfo

    2003-10-01

    In this talk we present a collection of selected topics concerning the structure of the proton and the fundamental interactions as seen inside it. These topics have been thoroughly covered by high energy experiments with ever increasing precision in recent years and beautifully illustrate our present knowledge of the standard model.

  10. Proton Radiobiology

    PubMed Central

    Tommasino, Francesco; Durante, Marco

    2015-01-01

    In addition to the physical advantages (Bragg peak), the use of charged particles in cancer therapy can be associated with distinct biological effects compared to X-rays. While heavy ions (densely ionizing radiation) are known to have an energy- and charge-dependent increased Relative Biological Effectiveness (RBE), protons should not be very different from sparsely ionizing photons. A slightly increased biological effectiveness is taken into account in proton treatment planning by assuming a fixed RBE of 1.1 for the whole radiation field. However, data emerging from recent studies suggest that, for several end points of clinical relevance, the biological response is differentially modulated by protons compared to photons. In parallel, research in the field of medical physics highlighted how variations in RBE that are currently neglected might actually result in deposition of significant doses in healthy organs. This seems to be relevant in particular for normal tissues in the entrance region and for organs at risk close behind the tumor. All these aspects will be considered and discussed in this review, highlighting how a re-discussion of the role of a variable RBE in proton therapy might be well-timed. PMID:25686476

  11. SU-E-T-133: Dosimetric Impact of Scan Orientation Relative to Target Motion During Spot Scanning Proton Therapy

    SciTech Connect

    Stoker, J; Summers, P; Li, X; Gomez, D; Sahoo, N; Zhu, X; Gillin, M

    2014-06-01

    Purpose: This study seeks to evaluate the dosimetric effects of intra-fraction motion during spot scanning proton beam therapy as a function of beam-scan orientation and target motion amplitude. Method: Multiple 4DCT scans were collected of a dynamic anthropomorphic phantom mimicking respiration amplitudes of 0 (static), 0.5, 1.0, and 1.5 cm. A spot-scanning treatment plan was developed on the maximum intensity projection image set, using an inverse-planning approach. Dynamic phantom motion was continuous throughout treatment plan delivery.The target nodule was designed to accommodate film and thermoluminescent dosimeters (TLD). Film and TLDs were uniquely labeled by location within the target. The phantom was localized on the treatment table using the clinically available orthogonal kV on-board imaging device. Film inserts provided data for dose uniformity; TLDs provided a 3% precision estimate of absolute dose. An inhouse script was developed to modify the delivery order of the beam spots, to orient the scanning direction parallel or perpendicular to target motion.TLD detector characterization and analysis was performed by the Imaging and Radiation Oncology Core group (IROC)-Houston. Film inserts, exhibiting a spatial resolution of 1mm, were analyzed to determine dose homogeneity within the radiation target. Results: Parallel scanning and target motions exhibited reduced target dose heterogeneity, relative to perpendicular scanning orientation. The average percent deviation in absolute dose for the motion deliveries relative to the static delivery was 4.9±1.1% for parallel scanning, and 11.7±3.5% (p<<0.05) for perpendicularly oriented scanning. Individual delivery dose deviations were not necessarily correlated to amplitude of motion for either scan orientation. Conclusions: Results demonstrate a quantifiable difference in dose heterogeneity as a function of scan orientation, more so than target amplitude. Comparison to the analyzed planar dose of a single

  12. Impact of margin size on the predicted risk of radiogenic second cancers following proton arc therapy and volumetric modulated arc therapy for prostate cancer

    NASA Astrophysics Data System (ADS)

    Rechner, Laura A.; Howell, Rebecca M.; Zhang, Rui; Newhauser, Wayne D.

    2012-12-01

    We previously determined that the predicted risk of radiogenic second cancer in the bladder and rectum after proton arc therapy (PAT) was less than or equal to that after volumetric modulated arc therapy (VMAT) with photons, but we did not consider the impact of margin size on that risk. The current study was thus conducted to evaluate margin size's effect on the predicted risks of second cancer for the two modalities and the relative risk between them. Seven treatment plans with margins ranging from 0 mm in all directions to 6 mm posteriorly and 8 mm in all other directions were considered for both modalities. We performed risk analyses using three risk models with varying amounts of cell sterilization and calculated ratios of risk for the corresponding PAT and VMAT plans. We found that the change in risk with margin size depended on the risk model but that the relative risk remained nearly constant with margin size, regardless of the amount of cell sterilization modeled. We conclude that while margin size influences the predicted risk of a second cancer for a given modality, it appears to affect both modalities in roughly equal proportions so that the relative risk between PAT and VMAT is approximately equivalent.

  13. Assessing the radiation-induced second cancer risk in proton therapy for pediatric brain tumors: the impact of employing a patient-specific aperture in pencil beam scanning.

    PubMed

    Geng, Changran; Moteabbed, Maryam; Xie, Yunhe; Schuemann, Jan; Yock, Torunn; Paganetti, Harald

    2016-01-01

    The purpose of this study was to compare the radiation-induced second cancer risks for in-field and out-of-field organs and tissues for pencil beam scanning (PBS) and passive scattering proton therapy (PPT) and assess the impact of adding patient-specific apertures to sharpen the penumbra in pencil beam scanning for pediatric brain tumor patients. Five proton therapy plans were created for each of three pediatric patients using PPT as well as PBS with two spot sizes (average sigma of ~17 mm and ~8 mm at isocenter) and choice of patient-specific apertures. The lifetime attributable second malignancy risks for both in-field and out-of-field tissues and organs were compared among five delivery techniques. The risk for in-field tissues was calculated using the organ equivalent dose, which is determined by the dose volume histogram. For out-of-field organs, the organ-specific dose equivalent from secondary neutrons was calculated using Monte Carlo and anthropomorphic pediatric phantoms. We find that either for small spot size PBS or for large spot size PBS, a patient-specific aperture reduces the in-field cancer risk to values lower than that for PPT. The reduction for large spot sizes (on average 43%) is larger than for small spot sizes (on average 21%). For out-of-field organs, the risk varies only marginally by employing a patient-specific aperture (on average from  -2% to 16% with increasing distance from the tumor), but is still one to two orders of magnitude lower than that for PPT. In conclusion, when pencil beam spot sizes are large, the addition of apertures to sharpen the penumbra decreases the in-field radiation-induced secondary cancer risk. There is a slight increase in out-of-field cancer risk as a result of neutron scatter from the aperture, but this risk is by far outweighed by the in-field risk benefit from using an aperture with a large PBS spot size. In general, the risk for developing a second malignancy in out-of-field organs for PBS remains

  14. Assessing the radiation-induced second cancer risk in proton therapy for pediatric brain tumors: the impact of employing a patient-specific aperture in pencil beam scanning.

    PubMed

    Geng, Changran; Moteabbed, Maryam; Xie, Yunhe; Schuemann, Jan; Yock, Torunn; Paganetti, Harald

    2016-01-01

    The purpose of this study was to compare the radiation-induced second cancer risks for in-field and out-of-field organs and tissues for pencil beam scanning (PBS) and passive scattering proton therapy (PPT) and assess the impact of adding patient-specific apertures to sharpen the penumbra in pencil beam scanning for pediatric brain tumor patients. Five proton therapy plans were created for each of three pediatric patients using PPT as well as PBS with two spot sizes (average sigma of ~17 mm and ~8 mm at isocenter) and choice of patient-specific apertures. The lifetime attributable second malignancy risks for both in-field and out-of-field tissues and organs were compared among five delivery techniques. The risk for in-field tissues was calculated using the organ equivalent dose, which is determined by the dose volume histogram. For out-of-field organs, the organ-specific dose equivalent from secondary neutrons was calculated using Monte Carlo and anthropomorphic pediatric phantoms. We find that either for small spot size PBS or for large spot size PBS, a patient-specific aperture reduces the in-field cancer risk to values lower than that for PPT. The reduction for large spot sizes (on average 43%) is larger than for small spot sizes (on average 21%). For out-of-field organs, the risk varies only marginally by employing a patient-specific aperture (on average from  -2% to 16% with increasing distance from the tumor), but is still one to two orders of magnitude lower than that for PPT. In conclusion, when pencil beam spot sizes are large, the addition of apertures to sharpen the penumbra decreases the in-field radiation-induced secondary cancer risk. There is a slight increase in out-of-field cancer risk as a result of neutron scatter from the aperture, but this risk is by far outweighed by the in-field risk benefit from using an aperture with a large PBS spot size. In general, the risk for developing a second malignancy in out-of-field organs for PBS remains

  15. Assessing the radiation-induced second cancer risk in proton therapy for pediatric brain tumors: the impact of employing a patient-specific aperture in pencil beam scanning

    NASA Astrophysics Data System (ADS)

    Geng, Changran; Moteabbed, Maryam; Xie, Yunhe; Schuemann, Jan; Yock, Torunn; Paganetti, Harald

    2016-01-01

    The purpose of this study was to compare the radiation-induced second cancer risks for in-field and out-of-field organs and tissues for pencil beam scanning (PBS) and passive scattering proton therapy (PPT) and assess the impact of adding patient-specific apertures to sharpen the penumbra in pencil beam scanning for pediatric brain tumor patients. Five proton therapy plans were created for each of three pediatric patients using PPT as well as PBS with two spot sizes (average sigma of ~17 mm and ~8 mm at isocenter) and choice of patient-specific apertures. The lifetime attributable second malignancy risks for both in-field and out-of-field tissues and organs were compared among five delivery techniques. The risk for in-field tissues was calculated using the organ equivalent dose, which is determined by the dose volume histogram. For out-of-field organs, the organ-specific dose equivalent from secondary neutrons was calculated using Monte Carlo and anthropomorphic pediatric phantoms. We find that either for small spot size PBS or for large spot size PBS, a patient-specific aperture reduces the in-field cancer risk to values lower than that for PPT. The reduction for large spot sizes (on average 43%) is larger than for small spot sizes (on average 21%). For out-of-field organs, the risk varies only marginally by employing a patient-specific aperture (on average from  -2% to 16% with increasing distance from the tumor), but is still one to two orders of magnitude lower than that for PPT. In conclusion, when pencil beam spot sizes are large, the addition of apertures to sharpen the penumbra decreases the in-field radiation-induced secondary cancer risk. There is a slight increase in out-of-field cancer risk as a result of neutron scatter from the aperture, but this risk is by far outweighed by the in-field risk benefit from using an aperture with a large PBS spot size. In general, the risk for developing a second malignancy in out-of-field organs for PBS remains

  16. Final Report: The Impact of Carbonate on Surface Protonation, Electron Transfer and Crystallization Reactions in Iron Oxide Nanoparticles and Colloids

    SciTech Connect

    Dixon, David Adams

    2013-07-02

    This project addresses key issues of importance in the geochemical behavior of iron oxides and in the geochemical cycling of carbon and iron. For Fe, we are specifically studying the influence of carbonate on electron transfer reactions, solid phase transformations, and the binding of carbonate to reactive sites on the edges of particles. The emphasis on carbonate arises because it is widely present in the natural environment, is known to bind strongly to oxide surfaces, is reactive on the time scales of interest, and has a speciation driven by acid-base reactions. The geochemical behavior of carbonate strongly influences global climate change and CO{sub 2} sequestration technologies. Our goal is to answer key questions with regards to specific site binding, electron transfer reactions, and crystallization reactions of iron oxides that impact both the geochemical cycling of iron and CO{sub 2} species. Our work is focused on the molecular level description of carbonate chemistry in solution including the prediction of isotope fractionation factors. We have also done work on critical atmospheric species.

  17. Intensity modulated proton therapy.

    PubMed

    Kooy, H M; Grassberger, C

    2015-07-01

    Intensity modulated proton therapy (IMPT) implies the electromagnetic spatial control of well-circumscribed "pencil beams" of protons of variable energy and intensity. Proton pencil beams take advantage of the charged-particle Bragg peak-the characteristic peak of dose at the end of range-combined with the modulation of pencil beam variables to create target-local modulations in dose that achieves the dose objectives. IMPT improves on X-ray intensity modulated beams (intensity modulated radiotherapy or volumetric modulated arc therapy) with dose modulation along the beam axis as well as lateral, in-field, dose modulation. The clinical practice of IMPT further improves the healthy tissue vs target dose differential in comparison with X-rays and thus allows increased target dose with dose reduction elsewhere. In addition, heavy-charged-particle beams allow for the modulation of biological effects, which is of active interest in combination with dose "painting" within a target. The clinical utilization of IMPT is actively pursued but technical, physical and clinical questions remain. Technical questions pertain to control processes for manipulating pencil beams from the creation of the proton beam to delivery within the patient within the accuracy requirement. Physical questions pertain to the interplay between the proton penetration and variations between planned and actual patient anatomical representation and the intrinsic uncertainty in tissue stopping powers (the measure of energy loss per unit distance). Clinical questions remain concerning the impact and management of the technical and physical questions within the context of the daily treatment delivery, the clinical benefit of IMPT and the biological response differential compared with X-rays against which clinical benefit will be judged. It is expected that IMPT will replace other modes of proton field delivery. Proton radiotherapy, since its first practice 50 years ago, always required the highest level of

  18. Intensity modulated proton therapy

    PubMed Central

    Grassberger, C

    2015-01-01

    Intensity modulated proton therapy (IMPT) implies the electromagnetic spatial control of well-circumscribed “pencil beams” of protons of variable energy and intensity. Proton pencil beams take advantage of the charged-particle Bragg peak—the characteristic peak of dose at the end of range—combined with the modulation of pencil beam variables to create target-local modulations in dose that achieves the dose objectives. IMPT improves on X-ray intensity modulated beams (intensity modulated radiotherapy or volumetric modulated arc therapy) with dose modulation along the beam axis as well as lateral, in-field, dose modulation. The clinical practice of IMPT further improves the healthy tissue vs target dose differential in comparison with X-rays and thus allows increased target dose with dose reduction elsewhere. In addition, heavy-charged-particle beams allow for the modulation of biological effects, which is of active interest in combination with dose “painting” within a target. The clinical utilization of IMPT is actively pursued but technical, physical and clinical questions remain. Technical questions pertain to control processes for manipulating pencil beams from the creation of the proton beam to delivery within the patient within the accuracy requirement. Physical questions pertain to the interplay between the proton penetration and variations between planned and actual patient anatomical representation and the intrinsic uncertainty in tissue stopping powers (the measure of energy loss per unit distance). Clinical questions remain concerning the impact and management of the technical and physical questions within the context of the daily treatment delivery, the clinical benefit of IMPT and the biological response differential compared with X-rays against which clinical benefit will be judged. It is expected that IMPT will replace other modes of proton field delivery. Proton radiotherapy, since its first practice 50 years ago, always required the

  19. Proton scaling

    SciTech Connect

    Canavan, Gregory H

    2009-01-01

    This note presents analytic estimates of the performance of proton beams in remote surveillance for nuclear materials. The analysis partitions the analysis into the eight steps used by a companion note: (1) Air scattering, (2) Neutron production in the ship and cargo, (3) Target detection probability, (4) Signal produced by target, (5) Attenuation of signal by ship and cargo, (6) Attenuation of signal by air, (7) Geometric dilution, and (8) Detector Efficiency. The above analyses indicate that the dominant air scattering and loss mechanisms for particle remote sensing are calculable with reliable and accepted tools. They make it clear that the conversion of proton beams into neutron sources rapidly goes to completion in all but thinnest targets, which means that proton interrogation is for all purposes executed by neutrons. Diffusion models and limiting approximations to them are simple and credible - apart from uncertainty over the cross sections to be used in them - and uncertainty over the structure of the vessels investigated. Multiplication is essentially unknown, in part because it depends on the details of the target and its shielding, which are unlikely to be known in advance. Attenuation of neutron fluxes on the way out are more complicated due to geometry, the spectrum of fission neutrons, and the details of their slowing down during egress. The attenuation by air is large but less uncertain. Detectors and technology are better known. The overall convolution of these effects lead to large but arguably tolerable levels of attenuation of input beams and output signals. That is particularly the case for small, mobile sensors, which can more than compensate for size with proximity to operate reliably while remaining below flux limits. Overall, the estimates used here appear to be of adequate accuracy for decisions. That assessment is strengthened by their agreement with companion calculations.

  20. Biological effects of proton radiation: an update.

    PubMed

    Girdhani, S; Sachs, R; Hlatky, L

    2015-09-01

    Proton radiation provides significant dosimetric advantages when compared with gamma radiation due to its superior energy deposition characteristics. Although the physical aspects of proton radiobiology are well understood, biological and clinical endpoints are understudied. The current practice to assume the relative biological effectiveness of low linear energy transfer (LET) protons to be a generic value of about 1.1 relative to photons likely obscures important unrecognised differentials in biological response between these radiation qualities. A deeper understanding of the biological properties induced by proton radiation would have both radiobiological and clinical impact. This article briefly points to some of the literature pertinent to the effects of protons on tissue-level processes that modify disease progression, such as angiogenesis, cell invasion and cancer metastasis. Recent findings hint that proton radiation may, in addition to offering improved radio-therapeutic targeting, be a means to provide a new dimension for increasing therapeutic benefits for patients by manipulating these tissue-level processes.

  1. Proton radiography to improve proton therapy treatment

    NASA Astrophysics Data System (ADS)

    Takatsu, J.; van der Graaf, E. R.; Van Goethem, M.-J.; van Beuzekom, M.; Klaver, T.; Visser, J.; Brandenburg, S.; Biegun, A. K.

    2016-01-01

    The quality of cancer treatment with protons critically depends on an accurate prediction of the proton stopping powers for the tissues traversed by the protons. Today, treatment planning in proton radiotherapy is based on stopping power calculations from densities of X-ray Computed Tomography (CT) images. This causes systematic uncertainties in the calculated proton range in a patient of typically 3-4%, but can become even 10% in bone regions [1,2,3,4,5,6,7,8]. This may lead to no dose in parts of the tumor and too high dose in healthy tissues [1]. A direct measurement of proton stopping powers with high-energy protons will allow reducing these uncertainties and will improve the quality of the treatment. Several studies have shown that a sufficiently accurate radiograph can be obtained by tracking individual protons traversing a phantom (patient) [4,6,10]. Our studies benefit from the gas-filled time projection chambers based on GridPix technology [2], developed at Nikhef, capable of tracking a single proton. A BaF2 crystal measuring the residual energy of protons was used. Proton radiographs of phantom consisting of different tissue-like materials were measured with a 30×30 mm2 150 MeV proton beam. Measurements were simulated with the Geant4 toolkit.First experimental and simulated energy radiographs are in very good agreement [3]. In this paper we focus on simulation studies of the proton scattering angle as it affects the position resolution of the proton energy loss radiograph. By selecting protons with a small scattering angle, the image quality can be improved significantly.

  2. Proton-Proton and Proton-Antiproton Colliders

    NASA Astrophysics Data System (ADS)

    Scandale, Walter

    2015-02-01

    In the last five decades, proton-proton and proton-antiproton colliders have been the most powerful tools for high energy physics investigations. They have also deeply catalyzed innovation in accelerator physics and technology. Among the large number of proposed colliders, only four have really succeeded in becoming operational: the ISR, the SppbarS, the Tevatron and the LHC. Another hadron collider, RHIC, originally conceived for ion-ion collisions, has also been operated part-time with polarized protons. Although a vast literature documenting them is available, this paper is intended to provide a quick synthesis of their main features and key performance.

  3. Synchrotron based proton drivers

    SciTech Connect

    Weiren Chou

    2002-09-19

    Proton drivers are the proton sources that produce intense short proton bunches. They have a wide range of applications. This paper discusses the proton drivers based on high-intensity proton synchrotrons. It gives a review of the high-intensity proton sources over the world and a brief report on recent developments in this field in the U.S. high-energy physics (HEP) community. The Fermilab Proton Driver is used as a case study for a number of challenging technical design issues.

  4. Proton Therapy - Accelerating Protons to Save Lives

    SciTech Connect

    Keppel, Cynthia

    2011-10-25

    In 1946, physicist Robert Wilson first suggested that protons could be used as a form of radiation therapy in the treatment of cancer because of the sharp drop-off that occurs on the distal edge of the radiation dose. Research soon confirmed that high-energy protons were particularly suitable for treating tumors near critical structures, such as the heart and spinal column. The precision with which protons can be delivered means that more radiation can be deposited into the tumor while the surrounding healthy tissue receives substantially less or, in some cases, no radiation. Since these times, particle accelerators have continuously been used in cancer therapy and today new facilities specifically designed for proton therapy are being built in many countries. Proton therapy has been hailed as a revolutionary cancer treatment, with higher cure rates and fewer side effects than traditional X-ray photon radiation therapy. Proton therapy is the modality of choice for treating certain small tumors of the eye, head or neck. Because it exposes less of the tissue surrounding a tumor to the dosage, proton therapy lowers the risk of secondary cancers later in life - especially important for young children. To date, over 80,000 patients worldwide have been treated with protons. Currently, there are nine proton radiation therapy facilities operating in the United States, one at the Hampton University Proton Therapy Institute. An overview of the treatment technology and this new center will be presented.

  5. Impact of OH Radical-Initiated H2CO3 Degradation in the Earth's Atmosphere via Proton-Coupled Electron Transfer Mechanism.

    PubMed

    Ghoshal, Sourav; Hazra, Montu K

    2016-02-01

    The decomposition of isolated carbonic acid (H2CO3) molecule into CO2 and H2O (H2CO3 → CO2 + H2O) is prevented by a large activation barrier (>35 kcal/mol). Nevertheless, it is surprising that the detection of the H2CO3 molecule has not been possible yet, and the hunt for the free H2CO3 molecule has become challenging not only in the Earth's atmosphere but also on Mars. In view of this fact, we report here the high levels of quantum chemistry calculations investigating both the energetics and kinetics of the OH radical-initiated H2CO3 degradation reaction to interpret the loss of the H2CO3 molecule in the Earth's atmosphere. It is seen from our study that proton-coupled electron transfer (PCET) and hydrogen atom transfer (HAT) are the two mechanisms by which the OH radical initiates the degradation of the H2CO3 molecule. Moreover, the PCET mechanism is potentially the important one, as the effective barrier, defined as the difference between the zero point vibrational energy (ZPE) corrected energy of the transition state and the total energy of the isolated starting reactants in terms of bimolecular encounters, for the PCET mechanism at the CCSD(T)/6-311++G(3df,3pd) level of theory is ∼3 to 4 kcal/mol lower than the effective barrier height associated with the HAT mechanism. The CCSD(T)/6-311++G(3df,3pd) level predicted effective barrier heights for the degradations of the two most stable conformers of H2CO3 molecule via the PCET mechanism are only ∼2.7 and 4.3 kcal/mol. A comparative reaction rate analysis at the CCSD(T)/6-311++G(3df,3pd) level of theory has also been carried out to explore the potential impact of the OH radical-initiated H2CO3 degradation relative to that from water (H2O), formic acid (FA), acetic acid (AA) and sulfuric acid (SA) assisted H2CO3 → CO2 + H2O decomposition reactions in both the Earth's troposphere and stratosphere. The comparison of the reaction rates reveals that, although the atmospheric concentration of the OH radical is

  6. Impact of OH Radical-Initiated H2CO3 Degradation in the Earth's Atmosphere via Proton-Coupled Electron Transfer Mechanism.

    PubMed

    Ghoshal, Sourav; Hazra, Montu K

    2016-02-01

    The decomposition of isolated carbonic acid (H2CO3) molecule into CO2 and H2O (H2CO3 → CO2 + H2O) is prevented by a large activation barrier (>35 kcal/mol). Nevertheless, it is surprising that the detection of the H2CO3 molecule has not been possible yet, and the hunt for the free H2CO3 molecule has become challenging not only in the Earth's atmosphere but also on Mars. In view of this fact, we report here the high levels of quantum chemistry calculations investigating both the energetics and kinetics of the OH radical-initiated H2CO3 degradation reaction to interpret the loss of the H2CO3 molecule in the Earth's atmosphere. It is seen from our study that proton-coupled electron transfer (PCET) and hydrogen atom transfer (HAT) are the two mechanisms by which the OH radical initiates the degradation of the H2CO3 molecule. Moreover, the PCET mechanism is potentially the important one, as the effective barrier, defined as the difference between the zero point vibrational energy (ZPE) corrected energy of the transition state and the total energy of the isolated starting reactants in terms of bimolecular encounters, for the PCET mechanism at the CCSD(T)/6-311++G(3df,3pd) level of theory is ∼3 to 4 kcal/mol lower than the effective barrier height associated with the HAT mechanism. The CCSD(T)/6-311++G(3df,3pd) level predicted effective barrier heights for the degradations of the two most stable conformers of H2CO3 molecule via the PCET mechanism are only ∼2.7 and 4.3 kcal/mol. A comparative reaction rate analysis at the CCSD(T)/6-311++G(3df,3pd) level of theory has also been carried out to explore the potential impact of the OH radical-initiated H2CO3 degradation relative to that from water (H2O), formic acid (FA), acetic acid (AA) and sulfuric acid (SA) assisted H2CO3 → CO2 + H2O decomposition reactions in both the Earth's troposphere and stratosphere. The comparison of the reaction rates reveals that, although the atmospheric concentration of the OH radical is

  7. Effects of electron temperature anisotropy on proton mirror instability evolution

    NASA Astrophysics Data System (ADS)

    Ahmadi, Narges; Germaschewski, Kai; Raeder, Joachim

    2016-06-01

    Proton mirror modes are large amplitude nonpropagating structures frequently observed in the magnetosheath. It has been suggested that electron temperature anisotropy can enhance the proton mirror instability growth rate while leaving the proton cyclotron instability largely unaffected, therefore causing the proton mirror instability to dominate the proton cyclotron instability in Earth's magnetosheath. Here we use particle-in-cell simulations to investigate the electron temperature anisotropy effects on proton mirror instability evolution. Contrary to the hypothesis, electron temperature anisotropy leads to excitement of the electron whistler instability. Our results show that the electron whistler instability grows much faster than the proton mirror instability and quickly consumes the electron-free energy so that there is no electron temperature anisotropy left to significantly impact the evolution of the proton mirror instability.

  8. Elastic proton-proton scattering at RHIC

    SciTech Connect

    Yip, K.

    2011-09-03

    Here we describe elastic proton+proton (p+p) scattering measurements at RHIC in p+p collisions with a special optics run of {beta}* {approx} 21 m at STAR, at the center-of-mass energy {radical}s = 200 GeV during the last week of the RHIC 2009 run. We present preliminary results of single and double spin asymmetries.

  9. What's In a Proton?

    ScienceCinema

    Brookhaven Lab

    2016-07-12

    Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

  10. Proton pump inhibitors

    MedlinePlus

    Proton pump inhibitors (PPIs) are medicines that work by reducing the amount of stomach acid made by ... Proton pump inhibitors are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This ...

  11. What's In a Proton?

    SciTech Connect

    Brookhaven Lab

    2009-07-08

    Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

  12. Proton: The Particle

    SciTech Connect

    Suit, Herman

    2013-11-01

    The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ≈10{sup 80}. Protons were created at 10{sup −6} –1 second after the Big Bang at ≈1.37 × 10{sup 10} years beforethe present. Proton life span has been experimentally determined to be ≥10{sup 34} years; that is, the age of the universe is 10{sup −24}th of the minimum life span of a proton. The abundance of the elements is hydrogen, ≈74%; helium, ≈24%; and heavier atoms, ≈2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ≈87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W{sup +}, W{sup −}, Z{sup 0}, and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ≈87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter.

  13. Proton: the particle.

    PubMed

    Suit, Herman

    2013-11-01

    The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ≈10(80). Protons were created at 10(-6) -1 second after the Big Bang at ≈1.37 × 10(10) years beforethe present. Proton life span has been experimentally determined to be ≥10(34) years; that is, the age of the universe is 10(-24)th of the minimum life span of a proton. The abundance of the elements is hydrogen, ≈74%; helium, ≈24%; and heavier atoms, ≈2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ≈87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W(+), W(-), Z(0), and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ≈87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter.

  14. Proton: the particle.

    PubMed

    Suit, Herman

    2013-11-01

    The purpose of this article is to review briefly the nature of protons: creation at the Big Bang, abundance, physical characteristics, internal components, and life span. Several particle discoveries by proton as the experimental tool are considered. Protons play important roles in science, medicine, and industry. This article was prompted by my experience in the curative treatment of cancer patients by protons and my interest in the nature of protons as particles. The latter has been stimulated by many discussions with particle physicists and reading related books and journals. Protons in our universe number ≈10(80). Protons were created at 10(-6) -1 second after the Big Bang at ≈1.37 × 10(10) years beforethe present. Proton life span has been experimentally determined to be ≥10(34) years; that is, the age of the universe is 10(-24)th of the minimum life span of a proton. The abundance of the elements is hydrogen, ≈74%; helium, ≈24%; and heavier atoms, ≈2%. Accordingly, protons are the dominant baryonic subatomic particle in the universe because ≈87% are protons. They are in each atom in our universe and thus involved in virtually every activity of matter in the visible universe, including life on our planet. Protons were discovered in 1919. In 1968, they were determined to be composed of even smaller particles, principally quarks and gluons. Protons have been the experimental tool in the discoveries of quarks (charm, bottom, and top), bosons (W(+), W(-), Z(0), and Higgs), antiprotons, and antineutrons. Industrial applications of protons are numerous and important. Additionally, protons are well appreciated in medicine for their role in radiation oncology and in magnetic resonance imaging. Protons are the dominant baryonic subatomic particle in the visible universe, comprising ≈87% of the particle mass. They are present in each atom of our universe and thus a participant in every activity involving matter. PMID:24074929

  15. TH-A-19A-03: Impact of Proton Dose Calculation Method On Delivered Dose to Lung Tumors: Experiments in Thorax Phantom and Planning Study in Patient Cohort

    SciTech Connect

    Grassberger, C; Daartz, J; Dowdell, S; Ruggieri, T; Sharp, G; Paganetti, H

    2014-06-15

    Purpose: Evaluate Monte Carlo (MC) dose calculation and the prediction of the treatment planning system (TPS) in a lung phantom and compare them in a cohort of 20 lung patients treated with protons. Methods: A 2-dimensional array of ionization chambers was used to evaluate the dose across the target in a lung phantom. 20 lung cancer patients on clinical trials were re-simulated using a validated Monte Carlo toolkit (TOPAS) and compared to the TPS. Results: MC increases dose calculation accuracy in lung compared to the clinical TPS significantly and predicts the dose to the target in the phantom within ±2%: the average difference between measured and predicted dose in a plane through the center of the target is 5.6% for the TPS and 1.6% for MC. MC recalculations in patients show a mean dose to the clinical target volume on average 3.4% lower than the TPS, exceeding 5% for small fields. The lower dose correlates significantly with aperture size and the distance of the tumor to the chest wall (Spearman's p=0.0002/0.004). For large tumors MC also predicts consistently higher V{sub 5} and V{sub 10} to the normal lung, due to a wider lateral penumbra, which was also observed experimentally. Critical structures located distal to the target can show large deviations, though this effect is very patient-specific. Conclusion: Advanced dose calculation techniques, such as MC, would improve treatment quality in proton therapy for lung cancer by avoiding systematic overestimation of target dose and underestimation of dose to normal lung. This would increase the accuracy of the relationships between dose and effect, concerning tumor control as well as normal tissue toxicity. As the role of proton therapy in the treatment of lung cancer continues to be evaluated in clinical trials, this is of ever-increasing importance. This work was supported by National Cancer Institute Grant R01CA111590.

  16. Study of proton radioactivities

    SciTech Connect

    Davids, C.N.; Back, B.B.; Henderson, D.J.

    1995-08-01

    About a dozen nuclei are currently known to accomplish their radioactive decay by emitting a proton. These nuclei are situated far from the valley of stability, and mark the very limits of existence for proton-rich nuclei: the proton drip line. A new 39-ms proton radioactivity was observed following the bombardment of a {sup 96}Ru target by a beam of 420-MeV {sup 78}Kr. Using the double-sided Si strip detector implantation system at the FMA, a proton group having an energy of 1.05 MeV was observed, correlated with the implantation of ions having mass 167. The subsequent daughter decay was identified as {sup 166}Os by its characteristic alpha decay, and therefore the proton emitter is assigned to the {sup 167}Ir nucleus. Further analysis showed that a second weak proton group from the same nucleus is present, indicating an isomeric state. Two other proton emitters were discovered recently at the FMA: {sup 171}Au and {sup 185}Bi, which is the heaviest known proton radioactivity. The measured decay energies and half-lives will enable the angular momentum of the emitted protons to be determined, thus providing spectroscopic information on nuclei that are beyond the proton drip line. In addition, the decay energy yields the mass of the nucleus, providing a sensitive test of mass models in this extremely proton-rich region of the chart of the nuclides. Additional searches for proton emitters will be conducted in the future, in order to extend our knowledge of the location of the proton drip line.

  17. Noncoplanarity effects in proton-proton bremsstrahlung

    SciTech Connect

    Li, Y.; Liou, M.K.; Timmermans, R.; Gibson, B.F.

    1998-10-01

    Noncoplanarity in proton-proton bremsstrahlung is investigated. Significant effects are observed for certain photon polar angles, {psi}{sub {gamma}}. Such noncoplanarity effects, not of dynamical origin, are possibly responsible for past disagreements between theory and experiment. The Harvard noncoplanar coordinate system, which avoids kinematic singularities in the cross section, is used in our calculations and is recommended for use in the analysis of experimental data. Alternative methods of presenting cross sections are discussed. {copyright} {ital 1998} {ital The American Physical Society}

  18. Mitochondrial proton and electron leaks

    PubMed Central

    Jastroch, Martin; Divakaruni, Ajit S.; Mookerjee, Shona; Treberg, Jason R.; Brand, Martin D.

    2011-01-01

    Mitochondrial proton and electron leak have a major impact on mitochondrial coupling efficiency and production of reactive oxygen species. In the first part of this chapter, we address the molecular nature of the basal and inducible proton leak pathways, and their physiological importance. The basal leak is unregulated, and a major proportion can be attributed to mitochondrial anion carriers, while the proton leak through the lipid bilayer appears to be minor. The basal proton leak is cell-type specific and correlates with metabolic rate. The inducible leak through the adenine nucleotide translocase (ANT) and uncoupling proteins (UCPs) can be activated by fatty acids, superoxide, or peroxidation products. The physiological role of inducible leak through UCP1 in mammalian brown adipose tissue is heat production, whereas the roles of non-mammalian UCP1 and its paralogous proteins, in particular UCP2 and UCP3, are not yet resolved. The second part of the chapter focuses on the electron leak that occurs in the mitochondrial electron transport chain. Exit of electrons prior to the reduction of oxygen to water at cytochrome c oxidase causes the production of superoxide. As the mechanisms of electron leak are crucial to understanding their physiological relevance, we summarize the mechanisms and topology of electron leak from Complex I and III in studies using isolated mitochondria. We also highlight recent progress and challenges of assessing electron leak in the living cell. Finally, we emphasise the importance of proton and electron leak as therapeutic targets in body weight regulation and insulin secretion. PMID:20533900

  19. Interplay effects in proton scanning for lung: a 4D Monte Carlo study assessing the impact of tumor and beam delivery parameters

    NASA Astrophysics Data System (ADS)

    Dowdell, S.; Grassberger, C.; Sharp, G. C.; Paganetti, H.

    2013-06-01

    Relative motion between a tumor and a scanning proton beam results in a degradation of the dose distribution (interplay effect). This study investigates the relationship between beam scanning parameters and the interplay effect, with the goal of finding parameters that minimize interplay. 4D Monte Carlo simulations of pencil beam scanning proton therapy treatments were performed using the 4DCT geometry of five lung cancer patients of varying tumor size (50.4-167.1 cc) and motion amplitude (2.9-30.1 mm). Treatments were planned assuming delivery in 35 × 2.5 Gy(RBE) fractions. The spot size, time to change the beam energy (τes), time required for magnet settling (τss), initial breathing phase, spot spacing, scanning direction, scanning speed, beam current and patient breathing period were varied for each of the five patients. Simulations were performed for a single fraction and an approximation of conventional fractionation. For the patients considered, the interplay effect could not be predicted using the superior-inferior motion amplitude alone. Larger spot sizes (σ ˜ 9-16 mm) were less susceptible to interplay, giving an equivalent uniform dose (EUD) of 99.0 ± 4.4% (1 standard deviation) in a single fraction compared to 86.1 ± 13.1% for smaller spots (σ ˜ 2-4 mm). The smaller spot sizes gave EUD values as low as 65.3% of the prescription dose in a single fraction. Reducing the spot spacing improved the target dose homogeneity. The initial breathing phase can have a significant effect on the interplay, particularly for shorter delivery times. No clear benefit was evident when scanning either parallel or perpendicular to the predominant axis of motion. Longer breathing periods decreased the EUD. In general, longer delivery times led to lower interplay effects. Conventional fractionation showed significant improvement in terms of interplay, giving a EUD of at least 84.7% and 100.0% of the prescription dose for the small and larger spot sizes respectively

  20. SU-E-T-452: Impact of Respiratory Motion On Robustly-Optimized Intensity-Modulated Proton Therapy to Treat Lung Cancers

    SciTech Connect

    Liu, W; Schild, S; Bues, M; Liao, Z; Sahoo, N; Park, P; Li, H; Li, Y; Li, X; Shen, J; Anand, A; Dong, L; Zhu, X; Mohan, R

    2014-06-01

    Purpose: We compared conventionally optimized intensity-modulated proton therapy (IMPT) treatment plans against the worst-case robustly optimized treatment plans for lung cancer. The comparison of the two IMPT optimization strategies focused on the resulting plans' ability to retain dose objectives under the influence of patient set-up, inherent proton range uncertainty, and dose perturbation caused by respiratory motion. Methods: For each of the 9 lung cancer cases two treatment plans were created accounting for treatment uncertainties in two different ways: the first used the conventional Method: delivery of prescribed dose to the planning target volume (PTV) that is geometrically expanded from the internal target volume (ITV). The second employed the worst-case robust optimization scheme that addressed set-up and range uncertainties through beamlet optimization. The plan optimality and plan robustness were calculated and compared. Furthermore, the effects on dose distributions of the changes in patient anatomy due to respiratory motion was investigated for both strategies by comparing the corresponding plan evaluation metrics at the end-inspiration and end-expiration phase and absolute differences between these phases. The mean plan evaluation metrics of the two groups were compared using two-sided paired t-tests. Results: Without respiratory motion considered, we affirmed that worst-case robust optimization is superior to PTV-based conventional optimization in terms of plan robustness and optimality. With respiratory motion considered, robust optimization still leads to more robust dose distributions to respiratory motion for targets and comparable or even better plan optimality [D95% ITV: 96.6% versus 96.1% (p=0.26), D5% - D95% ITV: 10.0% versus 12.3% (p=0.082), D1% spinal cord: 31.8% versus 36.5% (p =0.035)]. Conclusion: Worst-case robust optimization led to superior solutions for lung IMPT. Despite of the fact that robust optimization did not explicitly

  1. Interplay effects in proton scanning for lung: a 4D Monte Carlo study assessing the impact of tumor and beam delivery parameters.

    PubMed

    Dowdell, S; Grassberger, C; Sharp, G C; Paganetti, H

    2013-06-21

    Relative motion between a tumor and a scanning proton beam results in a degradation of the dose distribution (interplay effect). This study investigates the relationship between beam scanning parameters and the interplay effect, with the goal of finding parameters that minimize interplay. 4D Monte Carlo simulations of pencil beam scanning proton therapy treatments were performed using the 4DCT geometry of five lung cancer patients of varying tumor size (50.4-167.1 cc) and motion amplitude (2.9-30.1 mm). Treatments were planned assuming delivery in 35 × 2.5 Gy(RBE) fractions. The spot size, time to change the beam energy (τes), time required for magnet settling (τss), initial breathing phase, spot spacing, scanning direction, scanning speed, beam current and patient breathing period were varied for each of the five patients. Simulations were performed for a single fraction and an approximation of conventional fractionation. For the patients considered, the interplay effect could not be predicted using the superior-inferior motion amplitude alone. Larger spot sizes (σ ~ 9-16 mm) were less susceptible to interplay, giving an equivalent uniform dose (EUD) of 99.0 ± 4.4% (1 standard deviation) in a single fraction compared to 86.1 ± 13.1% for smaller spots (σ ~ 2-4 mm). The smaller spot sizes gave EUD values as low as 65.3% of the prescription dose in a single fraction. Reducing the spot spacing improved the target dose homogeneity. The initial breathing phase can have a significant effect on the interplay, particularly for shorter delivery times. No clear benefit was evident when scanning either parallel or perpendicular to the predominant axis of motion. Longer breathing periods decreased the EUD. In general, longer delivery times led to lower interplay effects. Conventional fractionation showed significant improvement in terms of interplay, giving a EUD of at least 84.7% and 100.0% of the prescription dose for the small and larger spot sizes respectively. The

  2. Z-dependence analysis of M x-ray production cross sections for heavy elements with 60≤Z≤90 by protons impact

    SciTech Connect

    Deghfel, B.; Kahoul, A.; Nekkab, M.

    2015-03-30

    Motivated by the large deviation between the experiment and the predictions of the most often used model of ionization process by a charged particle, namely ECPSSR model, a large database of experimental M-shell X-ray production cross-sections by protons energies varying from 0.1 to 4.0 MeV for elements with atomic number 60 ≤ Z ≤ 90, is collected from various sources published from 1980 till 2009 to deduce an empirical M x-ray production cross section. This latter is then deduced from the available experimental data as a function of the scaled velocity parameter by using the whole range of elements (collective analysis) or by introducing the dependence of these cross sections on the atomic number of the target, noted as “Z-dependence analysis” in addition to the collective one. The corresponding results and their deviation from the experimental data are presented for selected elements. Also, a comparison is made for selected elements between our results and other theoretical as well as experimental works.

  3. Z-dependence analysis of M x-ray production cross sections for heavy elements with 60≤Z≤90 by protons impact

    NASA Astrophysics Data System (ADS)

    Deghfel, B.; Kahoul, A.; Nekkab, M.

    2015-03-01

    Motivated by the large deviation between the experiment and the predictions of the most often used model of ionization process by a charged particle, namely ECPSSR model, a large database of experimental M-shell X-ray production cross-sections by protons energies varying from 0.1 to 4.0 MeV for elements with atomic number 60 ≤ Z ≤ 90, is collected from various sources published from 1980 till 2009 to deduce an empirical M x-ray production cross section. This latter is then deduced from the available experimental data as a function of the scaled velocity parameter by using the whole range of elements (collective analysis) or by introducing the dependence of these cross sections on the atomic number of the target, noted as "Z-dependence analysis" in addition to the collective one. The corresponding results and their deviation from the experimental data are presented for selected elements. Also, a comparison is made for selected elements between our results and other theoretical as well as experimental works.

  4. The Schwarzschild Proton

    SciTech Connect

    Haramein, Nassim

    2010-11-24

    We review our model of a proton that obeys the Schwarzschild condition. We find that only a very small percentage ({approx}10{sup -39}%) of the vacuum fluctuations available within a proton volume need be cohered and converted to mass-energy in order for the proton to meet the Schwarzschild condition. This proportion is equivalent to that between gravitation and the strong force where gravitation is thought to be {approx}10{sup -38} to 10{sup -40} weaker than the strong force. Gravitational attraction between two contiguous Schwarzschild protons can accommodate both nucleon and quark confinement. We calculate that two contiguous Schwarzschild protons would rotate at c and have a period of 10{sup -23} s and a frequency of 10{sup 22} Hz which is characteristic of the strong force interaction time and a close approximation of the gamma emission typically associated with nuclear decay. We include a scaling law and find that the Schwarzschild proton data point lies near the least squares trend line for organized matter. Using a semi-classical model, we find that a proton charge orbiting at a proton radius at c generates a good approximation to the measured anomalous magnetic moment.

  5. Electron-proton spectrometer

    NASA Technical Reports Server (NTRS)

    Winckler, J. R.

    1973-01-01

    An electron-proton spectrometer was designed to measure the geomagnetically trapped radiation in a geostationary orbit at 6.6 earth radii in the outer radiation belt. This instrument is to be flown on the Applications Technology Satellite-F (ATS-F). The electron-proton spectrometer consists of two permanent magnet surface barrier detector arrays and associated electronics capable of selecting and detecting electrons in three energy ranges: (1) 30-50 keV, (2) 150-200 keV, and (3) 500 keV and protons in three energy ranges. The electron-proton spectrometer has the capability of measuring the fluxes of electrons and protons in various directions with respect to the magnetic field lines running through the satellite. One magnet detector array system is implemented to scan between EME north and south through west, sampling the directional flux in 15 steps. The other magnet-detector array system is fixed looking toward EME east.

  6. Medical Applications: Proton Radiotherapy

    NASA Astrophysics Data System (ADS)

    Keppel, Cynthia

    2009-05-01

    Proton therapy is a highly advanced and precise form of radiation treatment for cancer. Due to the characteristic Bragg peak associated with ion energy deposition, proton therapy provides the radiation oncologist with an improved method of treatment localization within a patient, as compared with conventional radiation therapy using X-rays or electrons. Controlling disease and minimizing side effects are the twin aims of radiation treatment. Proton beams enhance the opportunity for both by facilitating maximal dose to tumor and minimal dose to surrounding tissue. In the United States, five proton radiotherapy centers currently treat cancer patients, with more in the construction phase. New facilities and enabling technologies abound. An overview of the treatment modality generally, as well as of the capabilities and research planned for the field and for the Hampton University Proton Therapy Institute in particular, will be presented.

  7. Four-dimensional Monte Carlo simulations demonstrating how the extent of intensity-modulation impacts motion effects in proton therapy lung treatments

    SciTech Connect

    Dowdell, Stephen; Paganetti, Harald; Grassberger, Clemens

    2013-12-15

    Purpose: To compare motion effects in intensity modulated proton therapy (IMPT) lung treatments with different levels of intensity modulation.Methods: Spot scanning IMPT treatment plans were generated for ten lung cancer patients for 2.5Gy(RBE) and 12Gy(RBE) fractions and two distinct energy-dependent spot sizes (σ∼8–17 mm and ∼2–4 mm). IMPT plans were generated with the target homogeneity of each individual field restricted to <20% (IMPT{sub 20%}). These plans were compared to full IMPT (IMPT{sub full}), which had no restriction on the single field homogeneity. 4D Monte Carlo simulations were performed upon the patient 4DCT geometry, including deformable image registration and incorporating the detailed timing structure of the proton delivery system. Motion effects were quantified via comparison of the results of the 4D simulations (4D-IMPT{sub 20%}, 4D-IMPT{sub full}) with those of a 3D Monte Carlo simulation (3D-IMPT{sub 20%}, 3D-IMPT{sub full}) upon the planning CT using the equivalent uniform dose (EUD), V{sub 95} and D{sub 1}-D{sub 99}. The effects in normal lung were quantified using mean lung dose (MLD) and V{sub 90%}.Results: For 2.5Gy(RBE), the mean EUD for the large spot size is 99.9%± 2.8% for 4D-IMPT{sub 20%} compared to 100.1%± 2.9% for 4D-IMPT{sub full}. The corresponding values are 88.6%± 8.7% (4D-IMPT{sub 20%}) and 91.0%± 9.3% (4D-IMPT{sub full}) for the smaller spot size. The EUD value is higher in 69.7% of the considered deliveries for 4D-IMPT{sub full}. The V{sub 95} is also higher in 74.7% of the plans for 4D-IMPT{sub full}, implying that IMPT{sub full} plans experience less underdose compared to IMPT{sub 20%}. However, the target dose homogeneity is improved in the majority (67.8%) of plans for 4D-IMPT{sub 20%}. The higher EUD and V{sub 95} suggests that the degraded homogeneity in IMPT{sub full} is actually due to the introduction of hot spots in the target volume, perhaps resulting from the sharper in-target dose gradients. The

  8. Proton-proton colliding beam facility ISABELLE

    SciTech Connect

    Hahn, H

    1980-01-01

    This paper attempts to present the status of the ISABELLE construction project, which has the objective of building a 400 + 400 GeV proton colliding beam facility. The major technical features of the superconducting accelerators with their projected performance are described. Progress made so far, difficulties encountered, and the program until completion in 1986 is briefly reviewed.

  9. Treatment planning optimisation in proton therapy.

    PubMed

    McGowan, S E; Burnet, N G; Lomax, A J

    2013-01-01

    The goal of radiotherapy is to achieve uniform target coverage while sparing normal tissue. In proton therapy, the same sources of geometric uncertainty are present as in conventional radiotherapy. However, an important and fundamental difference in proton therapy is that protons have a finite range, highly dependent on the electron density of the material they are traversing, resulting in a steep dose gradient at the distal edge of the Bragg peak. Therefore, an accurate knowledge of the sources and magnitudes of the uncertainties affecting the proton range is essential for producing plans which are robust to these uncertainties. This review describes the current knowledge of the geometric uncertainties and discusses their impact on proton dose plans. The need for patient-specific validation is essential and in cases of complex intensity-modulated proton therapy plans the use of a planning target volume (PTV) may fail to ensure coverage of the target. In cases where a PTV cannot be used, other methods of quantifying plan quality have been investigated. A promising option is to incorporate uncertainties directly into the optimisation algorithm. A further development is the inclusion of robustness into a multicriteria optimisation framework, allowing a multi-objective Pareto optimisation function to balance robustness and conformity. The question remains as to whether adaptive therapy can become an integral part of a proton therapy, to allow re-optimisation during the course of a patient's treatment. The challenge of ensuring that plans are robust to range uncertainties in proton therapy remains, although these methods can provide practical solutions.

  10. Treatment planning optimisation in proton therapy

    PubMed Central

    McGowan, S E; Burnet, N G; Lomax, A J

    2013-01-01

    ABSTRACT. The goal of radiotherapy is to achieve uniform target coverage while sparing normal tissue. In proton therapy, the same sources of geometric uncertainty are present as in conventional radiotherapy. However, an important and fundamental difference in proton therapy is that protons have a finite range, highly dependent on the electron density of the material they are traversing, resulting in a steep dose gradient at the distal edge of the Bragg peak. Therefore, an accurate knowledge of the sources and magnitudes of the uncertainties affecting the proton range is essential for producing plans which are robust to these uncertainties. This review describes the current knowledge of the geometric uncertainties and discusses their impact on proton dose plans. The need for patient-specific validation is essential and in cases of complex intensity-modulated proton therapy plans the use of a planning target volume (PTV) may fail to ensure coverage of the target. In cases where a PTV cannot be used, other methods of quantifying plan quality have been investigated. A promising option is to incorporate uncertainties directly into the optimisation algorithm. A further development is the inclusion of robustness into a multicriteria optimisation framework, allowing a multi-objective Pareto optimisation function to balance robustness and conformity. The question remains as to whether adaptive therapy can become an integral part of a proton therapy, to allow re-optimisation during the course of a patient's treatment. The challenge of ensuring that plans are robust to range uncertainties in proton therapy remains, although these methods can provide practical solutions. PMID:23255545

  11. Flash Proton Radiography

    NASA Astrophysics Data System (ADS)

    Merrill, Frank E.

    Protons were first investigated as radiographic probes as high energy proton accelerators became accessible to the scientific community in the 1960s. Like the initial use of X-rays in the 1800s, protons were shown to be a useful tool for studying the contents of opaque materials, but the electromagnetic charge of the protons opened up a new set of interaction processes which complicated their use. These complications in combination with the high expense of generating protons with energies high enough to penetrate typical objects resulted in proton radiography becoming a novelty, demonstrated at accelerator facilities, but not utilized to their full potential until the 1990s at Los Alamos. During this time Los Alamos National Laboratory was investigating a wide range of options, including X-rays and neutrons, as the next generation of probes to be used for thick object flash radiography. During this process it was realized that the charge nature of the protons, which was the source of the initial difficulty with this idea, could be used to recover this technique. By introducing a magnetic imaging lens downstream of the object to be radiographed, the blur resulting from scattering within the object could be focused out of the measurements, dramatically improving the resolution of proton radiography of thick systems. Imaging systems were quickly developed and combined with the temporal structure of a proton beam generated by a linear accelerator, providing a unique flash radiography capability for measurements at Los Alamos National Laboratory. This technique has now been employed at LANSCE for two decades and has been adopted around the world as the premier flash radiography technique for the study of dynamic material properties.

  12. Dosimetric impact of the low-dose envelope of scanned proton beams at a ProBeam facility: comparison of measurements with TPS and MC calculations

    NASA Astrophysics Data System (ADS)

    Würl, M.; Englbrecht, F.; Parodi, K.; Hillbrand, M.

    2016-01-01

    Due to the low-dose envelope of scanned proton beams, the dose output depends on the size of the irradiated field or volume. While this field size dependence has already been extensively investigated by measurements and Monte Carlo (MC) simulations for single pencil beams or monoenergetic fields, reports on the relevance of this effect for analytical dose calculation models are limited. Previous studies on this topic only exist for specific beamline designs. However, the amount of large-angle scattered primary and long-range secondary particles and thus the relevance of the low-dose envelope can considerably be influenced by the particular design of the treatment nozzle. In this work, we therefore addressed the field size dependence of the dose output at the commercially available ProBeam® beamline, which is being built in several facilities worldwide. We compared treatment planning dose calculations with ionization chamber (IC) measurements and MC simulations, using an experimentally validated FLUKA MC model of the scanning beamline. To this aim, monoenergetic square fields of three energies, as well as spherical target volumes were studied, including the investigation on the influence of the lateral spot spacing on the field size dependence. For the spherical target volumes, MC as well as analytical dose calculation were found in excellent agreement with the measurements in the center of the spread-out Bragg peak. In the plateau region, the treatment planning system (TPS) tended to overestimate the dose compared to MC calculations and IC measurements by up to almost 5% for the smallest investigated sphere and for small monoenergetic square fields. Narrower spot spacing slightly enhanced the field size dependence of the dose output. The deviations in the plateau dose were found to go in the clinically safe direction, i.e. the actual deposited dose outside the target was found to be lower than predicted by the TPS. Thus, the moderate overestimation of dose to

  13. Dosimetric impact of the low-dose envelope of scanned proton beams at a ProBeam facility: comparison of measurements with TPS and MC calculations.

    PubMed

    Würl, M; Englbrecht, F; Parodi, K; Hillbrand, M

    2016-01-21

    Due to the low-dose envelope of scanned proton beams, the dose output depends on the size of the irradiated field or volume. While this field size dependence has already been extensively investigated by measurements and Monte Carlo (MC) simulations for single pencil beams or monoenergetic fields, reports on the relevance of this effect for analytical dose calculation models are limited. Previous studies on this topic only exist for specific beamline designs. However, the amount of large-angle scattered primary and long-range secondary particles and thus the relevance of the low-dose envelope can considerably be influenced by the particular design of the treatment nozzle. In this work, we therefore addressed the field size dependence of the dose output at the commercially available ProBeam(®) beamline, which is being built in several facilities worldwide. We compared treatment planning dose calculations with ionization chamber (IC) measurements and MC simulations, using an experimentally validated FLUKA MC model of the scanning beamline. To this aim, monoenergetic square fields of three energies, as well as spherical target volumes were studied, including the investigation on the influence of the lateral spot spacing on the field size dependence. For the spherical target volumes, MC as well as analytical dose calculation were found in excellent agreement with the measurements in the center of the spread-out Bragg peak. In the plateau region, the treatment planning system (TPS) tended to overestimate the dose compared to MC calculations and IC measurements by up to almost 5% for the smallest investigated sphere and for small monoenergetic square fields. Narrower spot spacing slightly enhanced the field size dependence of the dose output. The deviations in the plateau dose were found to go in the clinically safe direction, i.e. the actual deposited dose outside the target was found to be lower than predicted by the TPS. Thus, the moderate overestimation of dose to

  14. Lyman-alpha emission from nonthermal proton beams

    NASA Technical Reports Server (NTRS)

    Orrall, F. Q.; Zirker, J. B.

    1976-01-01

    Nonthermal fast protons penetrating an atmosphere containing neutral hydrogen will produce some nonthermal fast neutrals which will radiate Doppler-shifted photons. The hydrogen line profiles observed from such an atmosphere will thus have nonthermal, partially polarized wings that contain information on the flux, energy spectrum, and direction of the incident proton beam. This paper develops the theory of this effect and applies it to proton beams from impulsive solar flares impacting on the sun's atmosphere. Calculations of the L-alpha profile from the region of impact have been made for the Vernazza-Avrett-Loeser solar atmosphere assuming proton energy fluxes and power-law spectra similar to those inferred for the electron beams believed responsible for hard X-ray bursts. The resulting profiles show that the effect should be detectable and that it could serve as a diagnostic for flare protons near their place of origin on the sun.

  15. Strangeness in the proton

    NASA Astrophysics Data System (ADS)

    Alberg, Mary

    2014-03-01

    Both perturbative and non-perturbative mechanisms contribute to strangeness in the proton sea. We have developed a hybrid model in which non-perturbative contributions are calculated in a meson cloud model which expands the proton in terms of meson-baryon states, and perturbative contributions are calculated in a statistical model which expands the proton in terms of quark-gluon states. The perturbative contributions are represented in the parton distributions of the ``bare'' hadrons in the meson cloud. We compare our results to the recent experimental data of ATLAS and HERMES. This research has been supported in part by NSF Award 1205686.

  16. Are protons nonidentical fermions?

    SciTech Connect

    Mart, T.

    2014-09-25

    We briefly review the progress of our investigation on the electric (charge) radius of the proton. In order to explain the recently measured proton radius, which is significantly smaller than the standard CODATA value, we assume that the real protons radii are not identical, they are randomly distributed in a certain range. To obtain the measured radius we average the radii and fit both the mean radius and the range. By using an averaged dipole form factor we obtain the charge radius r{sub E} = 0.8333 fm, in accordance with the recent measurement of the Lamb shift in muonic hydrogen.

  17. Apparatus for proton radiography

    DOEpatents

    Martin, Ronald L.

    1976-01-01

    An apparatus for effecting diagnostic proton radiography of patients in hospitals comprises a source of negative hydrogen ions, a synchrotron for accelerating the negative hydrogen ions to a predetermined energy, a plurality of stations for stripping extraction of a radiography beam of protons, means for sweeping the extracted beam to cover a target, and means for measuring the residual range, residual energy, or percentage transmission of protons that pass through the target. The combination of information identifying the position of the beam with information about particles traversing the subject and the back absorber is performed with the aid of a computer to provide a proton radiograph of the subject. In an alternate embodiment of the invention, a back absorber comprises a plurality of scintillators which are coupled to detectors.

  18. Proton channel models

    PubMed Central

    Pupo, Amaury; Baez-Nieto, David; Martínez, Agustín; Latorre, Ramón; González, Carlos

    2014-01-01

    Voltage-gated proton channels are integral membrane proteins with the capacity to permeate elementary particles in a voltage and pH dependent manner. These proteins have been found in several species and are involved in various physiological processes. Although their primary topology is known, lack of details regarding their structures in the open conformation has limited analyses toward a deeper understanding of the molecular determinants of their function and regulation. Consequently, the function-structure relationships have been inferred based on homology models. In the present work, we review the existing proton channel models, their assumptions, predictions and the experimental facts that support them. Modeling proton channels is not a trivial task due to the lack of a close homolog template. Hence, there are important differences between published models. This work attempts to critically review existing proton channel models toward the aim of contributing to a better understanding of the structural features of these proteins. PMID:24755912

  19. Limits of proton conductivity.

    PubMed

    Kreuer, Klaus-Dieter; Wohlfarth, Andreas

    2012-10-15

    Parasitic current seems to be the cause for the "highest proton conductivity" of a material reported to date. Kreuer and Wohlfarth verify this hypothesis by measuring the conductivity of the same materials after preparing them in a different way. They further explain the limits of proton conductivity and comment on the problems of determining the conductivity of small objects (e.g., whiskers, see picture).

  20. Proton beam therapy facility

    SciTech Connect

    Not Available

    1984-10-09

    It is proposed to build a regional outpatient medical clinic at the Fermi National Accelerator Laboratory (Fermilab), Batavia, Illinois, to exploit the unique therapeutic characteristics of high energy proton beams. The Fermilab location for a proton therapy facility (PTF) is being chosen for reasons ranging from lower total construction and operating costs and the availability of sophisticated technical support to a location with good access to patients from the Chicago area and from the entire nation. 9 refs., 4 figs., 26 tabs.

  1. Proton transport by halorhodopsin

    SciTech Connect

    Varo, G.; Brown, L.S.; Needleman, R.

    1996-05-28

    In halorhodopsin from Natronobacterium pharaonis, a light-driven chloride pump, the chloride binding site also binds azide. When azide is bound at this location the retinal Schiff base transiently deprotonates after photoexcitation with light >530 nm, like in the light-driven proton pump bacteriorhodopsin. As in the photocycle of bacteriorhodopsin, pyranine detects the release of protons to the bulk. The subsequent reprotonation of the Schiff base is also dependent on azide, but with different kinetics that suggest a shuttling of protons from the surface as described earlier for halorhodopsin from Halobacterium salinarium. The azide-dependent, bacteriorhodopsin-like photocycle results in active electrogenic proton transport in the cytoplasmic to extracellular direction, detected in cell envelope vesicle suspensions both with a potential-sensitive electrode and by measuring light-dependent pH change. We conclude that in halorhodopsin an azide bound to the extracellular side of the Schiff base, and another azide shuttling between the Schiff base and the cytoplasmic surface, fulfill the functions of Asp-85 and Asp-96, respectively, in bacteriorhodopsin. Thus, although halorhodopsin is normally a chloride ion pump, it evidently contains all structural requirements, except an internal proton acceptor and a donor, of a proton pump. This observation complements our earlier finding that when a chloride binding site was created in bacteriorhodopsin through replacement of Asp-85 with a threonine, that protein became a chloride ion pump. 52 refs., 9 figs.

  2. Protons and glucose metabolism in shock

    SciTech Connect

    Hochachka, P.W.

    1983-01-01

    When oxygen is limiting, animals can ferment glucose via several metabolic pathways varying in energetic efficiency and leading to various end products (such as lactate, succinate, or propionate). Because the pH dependence of H/sup +/ production by fermentation is opposite to that by hydrolysis of adenosine triphosphate formed in the fermentation, the total number of moles of protons generated is always two per mole of fermentable substrate. However, two and three times more adenosine triphosphate can be turned over per mole of protons produced in succinate and propionate fermentations, respectively, than in lactate fermentation. At its limit, this advantage would achieve the same balance between H/sup +/ production and H/sup +/ consumption during ATP cycling that is observed in aerobic metabolism, a situation observed in certain alcohol fermentations. Since proton balance during anaerobiosis is clearly adaptable, we consider possible impact and functions of net H/sup +/ accumulation during carbohydrate metabolism in endotoxin shock.

  3. Maximum proton kinetic energy and patient-generated neutron fluence considerations in proton beam arc delivery radiation therapy.

    PubMed

    Sengbusch, E; Pérez-Andújar, A; DeLuca, P M; Mackie, T R

    2009-02-01

    Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy of protons, immediately prior to entry into the patient, that must be reached by the treatment system. The commonly used value for the maximum kinetic energy required for a medical proton accelerator is 250 MeV, but it has not been demonstrated that this energy is indeed necessary to treat all or most patients eligible for proton therapy. This article quantifies the maximum kinetic energy of protons, immediately prior to entry into the patient, necessary to treat a given percentage of patients with rotational proton therapy, and examines the impact of this energy threshold on the cost and feasibility of a compact, gantry-mounted proton accelerator treatment system. One hundred randomized treatment plans from patients treated with IMRT were analyzed. The maximum radiological pathlength from the surface of the patient to the distal edge of the treatment volume was obtained for 180 degrees continuous arc proton therapy and for 180 degrees split arc proton therapy (two 90 degrees arcs) using CT# profiles from the Pinnacle (Philips Medical Systems, Madison, WI) treatment planning system. In each case, the maximum kinetic energy of protons, immediately prior to entry into the patient, that would be necessary to treat the patient was calculated using proton range tables for various media. In addition, Monte Carlo simulations were performed to quantify neutron production in a water phantom representing a patient as a function of the maximum proton kinetic energy achievable by a proton treatment system. Protons with a kinetic energy of 240 MeV, immediately prior to entry into the patient, were needed to treat 100% of patients in this study. However, it was shown that 90% of patients could be treated at 198 MeV, and 95% of patients could be treated at 207 MeV. Decreasing the

  4. Maximum proton kinetic energy and patient-generated neutron fluence considerations in proton beam arc delivery radiation therapy

    SciTech Connect

    Sengbusch, E.; Perez-Andujar, A.; DeLuca, P. M. Jr.; Mackie, T. R.

    2009-02-15

    Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy of protons, immediately prior to entry into the patient, that must be reached by the treatment system. The commonly used value for the maximum kinetic energy required for a medical proton accelerator is 250 MeV, but it has not been demonstrated that this energy is indeed necessary to treat all or most patients eligible for proton therapy. This article quantifies the maximum kinetic energy of protons, immediately prior to entry into the patient, necessary to treat a given percentage of patients with rotational proton therapy, and examines the impact of this energy threshold on the cost and feasibility of a compact, gantry-mounted proton accelerator treatment system. One hundred randomized treatment plans from patients treated with IMRT were analyzed. The maximum radiological pathlength from the surface of the patient to the distal edge of the treatment volume was obtained for 180 deg. continuous arc proton therapy and for 180 deg. split arc proton therapy (two 90 degree sign arcs) using CT profiles from the Pinnacle (Philips Medical Systems, Madison, WI) treatment planning system. In each case, the maximum kinetic energy of protons, immediately prior to entry into the patient, that would be necessary to treat the patient was calculated using proton range tables for various media. In addition, Monte Carlo simulations were performed to quantify neutron production in a water phantom representing a patient as a function of the maximum proton kinetic energy achievable by a proton treatment system. Protons with a kinetic energy of 240 MeV, immediately prior to entry into the patient, were needed to treat 100% of patients in this study. However, it was shown that 90% of patients could be treated at 198 MeV, and 95% of patients could be treated at 207 MeV. Decreasing the

  5. Maximum proton kinetic energy and patient-generated neutron fluence considerations in proton beam arc delivery radiation therapy

    PubMed Central

    Sengbusch, E.; Pérez-Andújar, A.; DeLuca, P. M.; Mackie, T. R.

    2009-01-01

    Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy of protons, immediately prior to entry into the patient, that must be reached by the treatment system. The commonly used value for the maximum kinetic energy required for a medical proton accelerator is 250 MeV, but it has not been demonstrated that this energy is indeed necessary to treat all or most patients eligible for proton therapy. This article quantifies the maximum kinetic energy of protons, immediately prior to entry into the patient, necessary to treat a given percentage of patients with rotational proton therapy, and examines the impact of this energy threshold on the cost and feasibility of a compact, gantry-mounted proton accelerator treatment system. One hundred randomized treatment plans from patients treated with IMRT were analyzed. The maximum radiological pathlength from the surface of the patient to the distal edge of the treatment volume was obtained for 180° continuous arc proton therapy and for 180° split arc proton therapy (two 90° arcs) using CT# profiles from the Pinnacle™ (Philips Medical Systems, Madison, WI) treatment planning system. In each case, the maximum kinetic energy of protons, immediately prior to entry into the patient, that would be necessary to treat the patient was calculated using proton range tables for various media. In addition, Monte Carlo simulations were performed to quantify neutron production in a water phantom representing a patient as a function of the maximum proton kinetic energy achievable by a proton treatment system. Protons with a kinetic energy of 240 MeV, immediately prior to entry into the patient, were needed to treat 100% of patients in this study. However, it was shown that 90% of patients could be treated at 198 MeV, and 95% of patients could be treated at 207 MeV. Decreasing the proton kinetic

  6. [Proton generator of superhigh frequency].

    PubMed

    Liberman, E A; Eĭdus, V L

    1981-01-01

    Possible mechanism of superhigh frequency (10(10)-10(12) Hz) electromagnetic oscillation generation by an external proton in a system of hydrogen bonds of biomacromolecules is briefly discussed. The external proton in a proton channel deforms the potential profile of the proton of hydrogen bond in such a way, that there appears a possibility of the low frequency proton tunneling along the hydrogen bond. The interaction with the neighbouring bonds leads to further lowering of the generated frequency.

  7. PREFACE: Transport phenomena in proton conducting media Transport phenomena in proton conducting media

    NASA Astrophysics Data System (ADS)

    Eikerling, Michael

    2011-06-01

    , charge-bearing species at interfaces and porous host materials on proton transport properties. As a common thread, articles in this special issue contribute to understanding the functionality provided by complex materials, beyond hydrogen bond fluctuations in water. The first group of articles (Smirnov et al, Henry et al, Medvedev and Stuchebrukhov) elucidates various aspects of the impact of local structural fluctuations, hydrogen bonding and long-range electrostatic forces on proton transfer across and at the surface of mitochondrial membranes. The second group of articles (Ilhan and Spohr, Allahyarov et al and Idupulapati et al) employ molecular dynamics simulations to rationalize vital dependencies of proton transport mechanisms in aqueous-based polymer electrolyte membranes on the nanoporous, phase-separated ionomer morphology, and on the level of hydration. The articles by Gebel et al, Boillat et al, and Aleksandrova et al employ small angle neutron scattering, neutron radiography, and electrochemical atomic force microscopy, respectively, to obtain detailed insights into the kinetics of water sorption, water distribution, water transport properties, as well as spatial maps of proton conductivity in fuel cell membranes. The contribution of Paschos et al provides a comprehensive review of phosphate-based solid state protonic conductors for intermediate temperature fuel cells. The topic of proton conductive materials for high-temperature, water-free operation of fuel cells is continued in the article of Verbraeken et al which addresses synthesis and characterization of a proton conducting perovskite. The guest editor wishes to acknowledge and thank all contributing authors for their commitment to this special issue. Moreover, I would like to thank the staff at IOP Publishing for coordinating submission and refereeing processes. Finally, for the readers, I hope that this special issue will be a valuable and stimulating source of insights into the versatile and

  8. Exotic Protonated Species Produced by UV-Induced Photofragmentation of a Protonated Dimer: Metastable Protonated Cinchonidine.

    PubMed

    Alata, Ivan; Scuderi, Debora; Lepere, Valeria; Steinmetz, Vincent; Gobert, Fabrice; Thiao-Layel, Loïc; Le Barbu-Debus, Katia; Zehnacker-Rentien, Anne

    2015-10-01

    A metastable protonated cinchona alkaloid was produced in the gas phase by UV-induced photodissociation (UVPD) of its protonated dimer in a Paul ion trap. The infrared multiple photon dissociation (IRMPD) spectrum of the molecular ion formed by UVPD was obtained and compared to DFT calculations to characterize its structure. The protonation site obtained thereby is not accessible by classical protonation ways. The protonated monomer directly formed in the ESI source or by collision-induced dissociation (CID) of the dimer undergoes protonation at the most basic alkaloid nitrogen. In contrast, protonation occurs at the quinoline aromatic ring nitrogen in the UVPD-formed monomer. PMID:26347997

  9. Exotic Protonated Species Produced by UV-Induced Photofragmentation of a Protonated Dimer: Metastable Protonated Cinchonidine.

    PubMed

    Alata, Ivan; Scuderi, Debora; Lepere, Valeria; Steinmetz, Vincent; Gobert, Fabrice; Thiao-Layel, Loïc; Le Barbu-Debus, Katia; Zehnacker-Rentien, Anne

    2015-10-01

    A metastable protonated cinchona alkaloid was produced in the gas phase by UV-induced photodissociation (UVPD) of its protonated dimer in a Paul ion trap. The infrared multiple photon dissociation (IRMPD) spectrum of the molecular ion formed by UVPD was obtained and compared to DFT calculations to characterize its structure. The protonation site obtained thereby is not accessible by classical protonation ways. The protonated monomer directly formed in the ESI source or by collision-induced dissociation (CID) of the dimer undergoes protonation at the most basic alkaloid nitrogen. In contrast, protonation occurs at the quinoline aromatic ring nitrogen in the UVPD-formed monomer.

  10. SU-E-T-493: Analysis of the Impact of Range and Setup Uncertainties On the Dose to Brain Stem and Whole Brain in the Passively Scattered Proton Therapy Plans

    SciTech Connect

    Sahoo, N; Zhu, X; Zhang, X; Poenisch, F; Li, H; Wu, R; Lii, M; Umfleet, W; Gillin, M; Mahajan, A; Grosshans, D

    2014-06-01

    Purpose: To quantify the impact of range and setup uncertainties on various dosimetric indices that are used to assess normal tissue toxicities of patients receiving passive scattering proton beam therapy (PSPBT). Methods: Robust analysis of sample treatment plans of six brain cancer patients treated with PSPBT at our facility for whom the maximum brain stem dose exceeded 5800 CcGE were performed. The DVH of each plan was calculated in an Eclipse treatment planning system (TPS) version 11 applying ±3.5% range uncertainty and ±3 mm shift of the isocenter in x, y and z directions to account for setup uncertainties. Worst-case dose indices for brain stem and whole brain were compared to their values in the nominal plan to determine the average change in their values. For the brain stem, maximum dose to 1 cc of volume, dose to 10%, 50%, 90% of volume (D10, D50, D90) and volume receiving 6000, 5400, 5000, 4500, 4000 CcGE (V60, V54, V50, V45, V40) were evaluated. For the whole brain, maximum dose to 1 cc of volume, and volume receiving 5400, 5000, 4500, 4000, 3000 CcGE (V54, V50, V45, V40 and V30) were assessed. Results: The average change in the values of these indices in the worst scenario cases from the nominal plan were as follows. Brain stem; Maximum dose to 1 cc of volume: 1.1%, D10: 1.4%, D50: 8.0%, D90:73.3%, V60:116.9%, V54:27.7%, V50: 21.2%, V45:16.2%, V40:13.6%,Whole brain; Maximum dose to 1 cc of volume: 0.3%, V54:11.4%, V50: 13.0%, V45:13.6%, V40:14.1%, V30:13.5%. Conclusion: Large to modest changes in the dosiemtric indices for brain stem and whole brain compared to nominal plan due to range and set up uncertainties were observed. Such potential changes should be taken into account while using any dosimetric parameters for outcome evaluation of patients receiving proton therapy.

  11. Impact of liquid water on oxygen reaction in cathode catalyst layer of proton exchange membrane fuel cell: A simple and physically sound model

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxian; Gao, Yuan

    2016-06-01

    When cells work at high current density, liquid water accumulates in their catalyst layer (CL) and the gaseous oxygen could dissolve into the water and the ionomer film simultaneously; their associated dissolved concentrations in equilibrium with the gaseous oxygen are also different. Based on a CL acquired using tomography, we present new methods in this paper to derive agglomerate models for partly saturated CL by viewing the movement and reaction of the dissolved oxygen in the two liquids (water and ionomer) and the agglomerate as two independent random processes. Oxygen dissolved in the water moves differently from oxygen dissolved in the ionomer, and to make the analysis tractable, we use an average distribution function to describe the average movement of all dissolved oxygen. A formula is proposed to describe this average distribution function, which, in combination with the exponential distribution assumed in the literature for oxygen reaction, leads to a simple yet physically sound agglomerate model. The model has three parameters which can be directly calculated from CL structure rather than by calibration. We explain how to calculate these parameters under different water contents for a given CL structure, and analyse the impact of liquid water on cell performance.

  12. SU-D-BRE-03: Dosimetric Impact of In-Air Spot Size Variations for Commissioning a Room-Matched Beam Model for Pencil Beam Scanning Proton Therapy

    SciTech Connect

    Zhang, Y; Giebeler, A; Mascia, A; Piskulich, F; Perles, L; Lepage, R; Dong, L

    2014-06-01

    Purpose: To quantitatively evaluate dosimetric consequence of spot size variations and validate beam-matching criteria for commissioning a pencil beam model for multiple treatment rooms. Methods: A planning study was first conducted by simulating spot size variations to systematically evaluate dosimetric impact of spot size variations in selected cases, which was used to establish the in-air spot size tolerance for beam matching specifications. A beam model in treatment planning system was created using in-air spot profiles acquired in one treatment room. These spot profiles were also acquired from another treatment room for assessing the actual spot size variations between the two treatment rooms. We created twenty five test plans with targets of different sizes at different depths, and performed dose measurement along the entrance, proximal and distal target regions. The absolute doses at those locations were measured using ionization chambers at both treatment rooms, and were compared against the calculated doses by the beam model. Fifteen additional patient plans were also measured and included in our validation. Results: The beam model is relatively insensitive to spot size variations. With an average of less than 15% measured in-air spot size variations between two treatment rooms, the average dose difference was −0.15% with a standard deviation of 0.40% for 55 measurement points within target region; but the differences increased to 1.4%±1.1% in the entrance regions, which are more affected by in-air spot size variations. Overall, our single-room based beam model in the treatment planning system agreed with measurements in both rooms < 0.5% within the target region. For fifteen patient cases, the agreement was within 1%. Conclusion: We have demonstrated that dosimetrically equivalent machines can be established when in-air spot size variations are within 15% between the two treatment rooms.

  13. Studying Proton-Proton Collisions Using Pythia

    NASA Astrophysics Data System (ADS)

    Zolotov, Adi

    2004-10-01

    At Brookhaven National Lab, the RHIC experiments are currently investigating, on a subatomic level, what happens when heavy ions collide at high speeds. This is done in order to create such high temperatures and densities that quarks are no longer bound to one another. This state of matter is called the Quark-Gluon Plasma (QGP). Evidence for the existence of the QGP may be the quenching of hadron jets, which occurs when the fast quarks or gluons lose so much energy in the hot, dense medium that they cannot survive. Then the jets of particles that these particles usually result in cannot be made. By studying the particle yield at high transverse momentum (Pt), one can probe what is happening to the jets created during collisions. Using Pythia, a standard model event generator based on the Lund String Model, we study jets of particles created when elementary protons collide. Then we know what should happen to jets at high transverse momentum transfer, when no QGP is present. Comparing the pt spectrum of jet partners generated by Pythia to RHIC results for proton-proton collisions shows that the two do in fact agree. This not only insures that the analysis of RHIC data is correct, but it also establishes a basis for comparison for Au-Au collisions. Comparing d+Au collision data to the Pythia Pt spectrum of jets with leading baryon and meson triggers, we found good agreement. Thus the jet production does not change drastically in nature in the presence of a cold nuclear medium.

  14. Proton charge extensions

    NASA Astrophysics Data System (ADS)

    Stryker, Jesse R.; Miller, Gerald A.

    2016-01-01

    We examine how corrections to S -state energy levels En S in hydrogenic atoms due to the finite proton size are affected by moments of the proton charge distribution. The corrections to En S are computed moment by moment. The results demonstrate that the next-to-leading order term in the expansion is of order rp/aB times the size of the leading order term. Our analysis thus dispels any concern that the larger relative size of this term for muonic hydrogen versus electronic hydrogen might account for the current discrepancy of proton radius measurements extracted from the two systems. Furthermore, the next-to-leading order term in powers of rp/aB that we derive from a dipole proton form factor is proportional to , rather than , as would be expected from the scalar nature of the form factor. The dependence of the finite-size correction on and higher odd-power moments is shown to be a general result for any spherically symmetric proton charge distribution. A method for computing the moment expansion of the finite-size correction to arbitrary order is introduced and the results are tabulated for principal quantum numbers up to n =7 .

  15. Protons and how they are transported by proton pumps.

    PubMed

    Buch-Pedersen, M J; Pedersen, B P; Veierskov, B; Nissen, P; Palmgren, M G

    2009-01-01

    The very high mobility of protons in aqueous solutions demands special features of membrane proton transporters to sustain efficient yet regulated proton transport across biological membranes. By the use of the chemical energy of ATP, plasma-membrane-embedded ATPases extrude protons from cells of plants and fungi to generate electrochemical proton gradients. The recently published crystal structure of a plasma membrane H(+)-ATPase contributes to our knowledge about the mechanism of these essential enzymes. Taking the biochemical and structural data together, we are now able to describe the basic molecular components that allow the plasma membrane proton H(+)-ATPase to carry out proton transport against large membrane potentials. When divergent proton pumps such as the plasma membrane H(+)-ATPase, bacteriorhodopsin, and F(O)F(1) ATP synthase are compared, unifying mechanistic premises for biological proton pumps emerge. Most notably, the minimal pumping apparatus of all pumps consists of a central proton acceptor/donor, a positively charged residue to control pK(a) changes of the proton acceptor/donor, and bound water molecules to facilitate rapid proton transport along proton wires.

  16. Synchrotron radiation from protons

    SciTech Connect

    Dutt, S.K.

    1992-12-01

    Synchrotron radiation from protons, though described by the same equations as the radiation from electrons, exhibits a number of interesting features on account of the parameters reached in praxis. In this presentation, we shall point out some of the features relating to (i) normal synchrotron radiation from dipoles in proton machines such as the High Energy Booster and the Superconducting Super Collider; (ii) synchrotron radiation from short dipoles, and its application to light monitors for proton machines, and (iii) synchrotron radiation from undulators in the limit when, the deflection parameter is much smaller than unity. The material for this presentation is taken largely from the work of Hofmann, Coisson, Bossart, and their collaborators, and from a paper by Kim. We shall emphasize the qualitative aspects of synchrotron radiation in the cases mentioned above, making, when possible, simple arguments for estimating the spectral and angular properties of the radiation. Detailed analyses can be found in the literature.

  17. The physics of proton therapy

    PubMed Central

    Newhauser, Wayne D; Zhang, Rui

    2015-01-01

    The physics of proton therapy has advanced considerably since it was proposed in 1946. Today analytical equations and numerical simulation methods are available to predict and characterize many aspects of proton therapy. This article reviews the basic aspects of the physics of proton therapy, including proton interaction mechanisms, proton transport calculations, the determination of dose from therapeutic and stray radiations, and shielding design. The article discusses underlying processes as well as selected practical experimental and theoretical methods. We conclude by briefly speculating on possible future areas of research of relevance to the physics of proton therapy. PMID:25803097

  18. Proton Radiography With Timepix Based Time Projection Chambers.

    PubMed

    Biegun, Aleksandra K; Visser, Jan; Klaver, Tom; Ghazanfari, Nafiseh; van Goethem, Marc-Jan; Koffeman, Els; van Beuzekom, Martin; Brandenburg, Sytze

    2016-04-01

    The development of a proton radiography system to improve the imaging of patients in proton beam therapy is described. The system comprises gridpix based time projection chambers, which are based on the Timepix chip designed by the Medipix collaboration, for tracking the protons. This type of detector was chosen to have minimal impact on the actual determination of the proton tracks by the tracking detectors. To determine the residual energy of the protons, a BaF 2 crystal with a photomultiplier tube is used. We present data taken in a feasibility experiment with phantoms that represent tissue equivalent materials found in the human body. The obtained experimental results show a good agreement with the performed simulations. PMID:26701179

  19. On forecasting the onset of Solar Proton Events

    NASA Astrophysics Data System (ADS)

    Núñez, Marlon; Fidalgo, Raúl; Morales, Rafael

    A major problem for predicting the onset of Solar Proton Events is the detection of the magnetic connection between the flare and the earth. If there is a magnetic connection, the particles accelerated by a large solar event may impact the earth and produce the onset of a solar energetic proton event. Current physical models cannot predict the onset of a SPE mainly because of the chaotic conditions within the IMF structure. Kiplinger (1995) reported a high correlation between the existence of 10 MeV protons at Earth and a characteristic pattern of X-ray spectral evolution for several associated flares. We propose a practical approach that tries to detect the time intervals of this correlation. Our assumption is that a high correlation betwewn X-ray and protons at Earth is an important symptom of a magnetic connection and may help to prevent Solar Proton Events.

  20. Shielding of relativistic protons.

    PubMed

    Bertucci, A; Durante, M; Gialanella, G; Grossi, G; Manti, L; Pugliese, M; Scampoli, P; Mancusi, D; Sihver, L; Rusek, A

    2007-06-01

    Protons are the most abundant element in the galactic cosmic radiation, and the energy spectrum peaks around 1 GeV. Shielding of relativistic protons is therefore a key problem in the radiation protection strategy of crewmembers involved in long-term missions in deep space. Hydrogen ions were accelerated up to 1 GeV at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, New York. The proton beam was also shielded with thick (about 20 g/cm2) blocks of lucite (PMMA) or aluminium (Al). We found that the dose rate was increased 40-60% by the shielding and decreased as a function of the distance along the axis. Simulations using the General-Purpose Particle and Heavy-Ion Transport code System (PHITS) show that the dose increase is mostly caused by secondary protons emitted by the target. The modified radiation field after the shield has been characterized for its biological effectiveness by measuring chromosomal aberrations in human peripheral blood lymphocytes exposed just behind the shield block, or to the direct beam, in the dose range 0.5-3 Gy. Notwithstanding the increased dose per incident proton, the fraction of aberrant cells at the same dose in the sample position was not significantly modified by the shield. The PHITS code simulations show that, albeit secondary protons are slower than incident nuclei, the LET spectrum is still contained in the low-LET range (<10 keV/microm), which explains the approximately unitary value measured for the relative biological effectiveness. PMID:17256178

  1. Proton irradiation and endometriosis

    SciTech Connect

    Wood, D.H.; Yochmowitz, M.G.; Salmon, Y.L.; Eason, R.L.; Boster, R.A.

    1983-08-01

    It was found that female rhesus monkeys given single total-body exposures of protons of varying energies developed endometriosis at a frequency significantly higher than that of nonirradiated animals of the same age. The minimum latency period was determined to be 7 years after the proton exposure. The doses and energies of the radiation received by the experimental animals were within the range that could be received by an aircrew member in near-earth orbit during a random solar flare event. It is concluded that endometriosis should be a consideration in assessing the risk of delayed radiation effects in female crew members. 15 references.

  2. Proton-Proton Scattering at 105 Mev and 75 Mev

    DOE R&D Accomplishments Database

    Birge, R. W.; Kruse, U. E.; Ramsey, N. F.

    1951-01-31

    The scattering of protons by protons provides an important method for studying the nature of nuclear forces. Recent proton-proton scattering experiments at energies as high as thirty Mev{sup 1} have failed to show any appreciable contribution to the cross section from higher angular momentum states, but it is necessary to bring in tensor forces to explain the magnitude of the observed cross section.

  3. Predictions of diffractive cross sections in proton-proton collisions

    SciTech Connect

    Goulianos, Konstantin

    2013-04-15

    We review our pre-LHC predictions of the total, elastic, total-inelastic, and diffractive components of proton-proton cross sections at high energies, expressed in the form of unitarized expressions based on a special parton-model approach to diffraction employing inclusive proton parton distribution functions and QCD color factors and compare with recent LHC results.

  4. Proton Nucleus Elastic Scattering Data.

    1993-08-18

    Version 00 The Proton Nucleus Elastic Scattering Data file PNESD contains the numerical data and the related bibliography for the differential elastic cross sections, polarization and integral nonelastic cross sections for elastic proton-nucleus scattering.

  5. Proton therapy in clinical practice

    PubMed Central

    Liu, Hui; Chang, Joe Y.

    2011-01-01

    Radiation dose escalation and acceleration improves local control but also increases toxicity. Proton radiation is an emerging therapy for localized cancers that is being sought with increasing frequency by patients. Compared with photon therapy, proton therapy spares more critical structures due to its unique physics. The physical properties of a proton beam make it ideal for clinical applications. By modulating the Bragg peak of protons in energy and time, a conformal radiation dose with or without intensity modulation can be delivered to the target while sparing the surrounding normal tissues. Thus, proton therapy is ideal when organ preservation is a priority. However, protons are more sensitive to organ motion and anatomy changes compared with photons. In this article, we review practical issues of proton therapy, describe its image-guided treatment planning and delivery, discuss clinical outcome for cancer patients, and suggest challenges and the future development of proton therapy. PMID:21527064

  6. The Search for Proton Decay.

    ERIC Educational Resources Information Center

    Marshak, Marvin L.

    1984-01-01

    Provides the rationale for and examples of experiments designed to test the stability of protons and bound neutrons. Also considers the unification question, cosmological implications, current and future detectors, and current status of knowledge on proton decay. (JN)

  7. Proton bunch compression strategies

    SciTech Connect

    Lebedev, Valeri; /Fermilab

    2009-10-01

    The paper discusses main limitations on the beam power and other machine parameters for a 4 MW proton driver for muon collider. The strongest limitation comes from a longitudinal microwave instability limiting the beam power to about 1 MW for an 8 GeV compressor ring.

  8. High Power Proton Facilities

    NASA Astrophysics Data System (ADS)

    Nagaitsev, Sergei

    2015-04-01

    This presentation will provide an overview of the capabilities and challenges of high intensity proton accelerators, such as J-PARC, Fermilab MI, SNS, ISIS, PSI, ESS (in the future) and others. The presentation will focus on lessons learned, new concepts, beam loss mechanisms and methods to mitigate them.

  9. Direct probe of the intrinsic charm content of the proton

    NASA Astrophysics Data System (ADS)

    Boettcher, Tom; Ilten, Philip; Williams, Mike

    2016-04-01

    Measurement of Z bosons produced in association with charm jets (Z c ) in proton-proton collisions in the forward region provides a direct probe of a potential nonperturbative (intrinsic) charm component in the proton wave function. We provide a detailed study of the potential to measure Z c production at the LHCb experiment in Runs 2 and 3 of the LHC. The sensitivity to valence-like (sea-like) intrinsic charm is predicted to be ⟨x ⟩IC≳0.3 %(1 %). The impact of intrinsic charm on Higgs production at the LHC, including H c , is also discussed in detail.

  10. Exploring universality of transversity in proton-proton collisions

    NASA Astrophysics Data System (ADS)

    Radici, Marco; Ricci, Alessandro M.; Bacchetta, Alessandro; Mukherjee, Asmita

    2016-08-01

    We consider the azimuthal correlations of charged hadron pairs with large total transverse momentum and small relative momentum, produced in proton-proton collisions with one transversely polarized proton. One of these correlations directly probes the chiral-odd transversity parton distribution in connection with a chiral-odd interference fragmentation function. We present predictions for this observable based on previous extractions of transversity (from charged pion pair production in semi-inclusive deep-inelastic scattering) and of the interference fragmentation function (from the production of back-to-back charged pion pairs in electron-positron annihilations). All analyses are performed in the framework of collinear factorization. We compare our predictions to the recent data on proton-proton collisions released by the STAR Collaboration at RHIC, and we find them reasonably compatible. This comparison confirms for the first time the predicted role of transversity in proton-proton collisions, and it allows us to test its universality.

  11. Proton radiography and tomography with application to proton therapy

    PubMed Central

    Allinson, N M; Evans, P M

    2015-01-01

    Proton radiography and tomography have long promised benefit for proton therapy. Their first suggestion was in the early 1960s and the first published proton radiographs and CT images appeared in the late 1960s and 1970s, respectively. More than just providing anatomical images, proton transmission imaging provides the potential for the more accurate estimation of stopping-power ratio inside a patient and hence improved treatment planning and verification. With the recent explosion in growth of clinical proton therapy facilities, the time is perhaps ripe for the imaging modality to come to the fore. Yet many technical challenges remain to be solved before proton CT scanners become commonplace in the clinic. Research and development in this field is currently more active than at any time with several prototype designs emerging. This review introduces the principles of proton radiography and tomography, their historical developments, the raft of modern prototype systems and the primary design issues. PMID:26043157

  12. Proton transfer at carbon.

    PubMed

    Richard, J P; Amyes, T L

    2001-12-01

    The viability of living systems requires that C--H bonds of biological molecules be stable in water, but that there also be a mechanism for shortening the timescale for their heterolytic cleavage through enzymatic catalysis of a variety of catabolic and metabolic reactions. An understanding of the mechanism of enzymatic catalysis of proton transfer at carbon requires the integration of results of studies to determine the structure of the enzyme-substrate complex with model studies on the mechanism for the non-enzymatic reaction in water, and the effect of the local protein environment on the stability of the transition state for this reaction. A common theme is the importance of electrostatic interactions in providing stabilization of bound carbanion intermediates of enzyme-catalyzed proton-transfer reactions.

  13. Quantum Dynamics in Continuum for Proton Transport I: Basic Formulation

    PubMed Central

    Chen, Duan; Wei, Guo-Wei

    2012-01-01

    Proton transport is one of the most important and interesting phenomena in living cells. The present work proposes a multiscale/multiphysics model for the understanding of the molecular mechanism of proton transport in transmembrane proteins. We describe proton dynamics quantum mechanically via a density functional approach while implicitly model other solvent ions as a dielectric continuum to reduce the number of degrees of freedom. The densities of all other ions in the solvent are assumed to obey the Boltzmann distribution. The impact of protein molecular structure and its charge polarization on the proton transport is considered explicitly at the atomic level. We formulate a total free energy functional to put proton kinetic and potential energies as well as electrostatic energy of all ions on an equal footing. The variational principle is employed to derive nonlinear governing equations for the proton transport system. Generalized Poisson-Boltzmann equation and Kohn-Sham equation are obtained from the variational framework. Theoretical formulations for the proton density and proton conductance are constructed based on fundamental principles. The molecular surface of the channel protein is utilized to split the discrete protein domain and the continuum solvent domain, and facilitate the multiscale discrete/continuum/quantum descriptions. A number of mathematical algorithms, including the Dirichlet to Neumann mapping, matched interface and boundary method, Gummel iteration, and Krylov space techniques are utilized to implement the proposed model in a computationally efficient manner. The Gramicidin A (GA) channel is used to demonstrate the performance of the proposed proton transport model and validate the efficiency of proposed mathematical algorithms. The electrostatic characteristics of the GA channel is analyzed with a wide range of model parameters. The proton conductances are studied over a number of applied voltages and reference concentrations. A

  14. Proton therapy in the clinic.

    PubMed

    DeLaney, Thomas F

    2011-01-01

    The clinical advantage for proton radiotherapy over photon approaches is the marked reduction in integral dose to the patient, due to the absence of exit dose beyond the proton Bragg peak. The integral dose with protons is approximately 60% lower than that with any external beam photon technique. Pediatric patients, because of their developing normal tissues and anticipated length of remaining life, are likely to have the maximum clinical gain with the use of protons. Proton therapy may also allow treatment of some adult tumors to much more effective doses, because of normal tissue sparing distal to the tumor. Currently, the most commonly available proton treatment technology uses 3D conformal approaches based on (a) distal range modulation, (b) passive scattering of the proton beam in its x- and y-axes, and (c) lateral beam-shaping. It is anticipated that magnetic pencil beam scanning will become the dominant mode of proton delivery in the future, which will lower neutron scatter associated with passively scattered beam lines, reduce the need for expensive beam-shaping devices, and allow intensity-modulated proton radiotherapy. Proton treatment plans are more sensitive to variations in tumor size and normal tissue changes over the course of treatment than photon plans, and it is expected that adaptive radiation therapy will be increasingly important for proton therapy as well. While impressive treatment results have been reported with protons, their cost is higher than for photon IMRT. Hence, protons should ideally be employed for anatomic sites and tumors not well treated with photons. While protons appear cost-effective for pediatric tumors, their cost-effectiveness for treatment of some adult tumors, such as prostate cancer, is uncertain. Comparative studies have been proposed or are in progress to more rigorously assess their value for a variety of sites. The utility of proton therapy will be enhanced by technological developments that reduce its cost

  15. Smashing Protons to Smithereens

    SciTech Connect

    Marc-André Pleier

    2010-05-05

    Pleier discusses the extraordinary research taking place at the Large Hadron Collider (LHC) — the world’s newest, biggest, and highest energy particle accelerator located at CERN. Pleier is one of hundreds of researchers from around the world working on ATLAS, a seven-story particle detector positioned at a point where the LHC’s oppositely circulating beams of protons slam into one another head-on.

  16. Proton conducting cerate ceramics

    SciTech Connect

    Coffey, G.W.; Pederson, L.R.; Armstrong, T.R.; Bates, J.L.; Weber, W.J.

    1995-08-01

    Cerate perovskites of the general formula AM{sub x}Ce{sub 1-x}O{sub 3-{delta}}, where A = Sr or Ba and where M = Gd, Nd, Y, Yb or other rare earth dopant, are known to conduct a protonic current. Such materials may be useful as the electrolyte in a solid oxide fuel cell operating at intermediate temperatures, as an electrochemical hydrogen separation membrane, or as a hydrogen sensor. Conduction mechanisms in these materials were evaluated using dc cyclic voltammetry and mass spectrometry, allowing currents and activation energies for proton, electron, and oxygen ion contributions to the total current to be determined. For SrYb{sub 0.05}Ce{sub 0.95}O{sub 3-{delta}}, one of the best and most environmentally stable compositions, proton conduction followed two different mechanisms: a low temperature process, characterized by an activation energy of 0.42{+-}0.04 eV, and a high temperature process, characterized by an activation energy of 1.38{+-}0.13 eV. It is believed that the low temperature process is dominated by grain boundary conduction while bulk conduction is responsible for the high temperature process. The activation energy for oxygen ion conduction (0.97{+-}0.10 eV) agrees well with other oxygen conductors, while that for electronic conduction, 0.90{+-}0.09 eV, is affected by a temperature-dependent electron carrier concentration. Evaluated by direct measurement of mass flux through a dense ceramic with an applied dc field, oxygen ions were determined to be the majority charge carrier except at the lowest temperatures, followed by electrons and then protons.

  17. Smashing Protons to Smithereens

    ScienceCinema

    Marc-André Pleier

    2016-07-12

    Pleier discusses the extraordinary research taking place at the Large Hadron Collider (LHC) — the world’s newest, biggest, and highest energy particle accelerator located at CERN. Pleier is one of hundreds of researchers from around the world working on ATLAS, a seven-story particle detector positioned at a point where the LHC’s oppositely circulating beams of protons slam into one another head-on.

  18. Polarized protons at RHIC

    SciTech Connect

    Makdisi, Y.

    1992-10-01

    The approval for construction of the Relativistic Heavy Ion Collider (RHIC) provides a potential opportunity to collide polarized proton beams at energies up to 500 GeV in the center of mass and high luminosities approaching 2 {times} 10{sup 32}/cm{sup 2}/sec. This capability is enhanced by the fact that the AGS has already accelerated polarized protons and relies on the newly completed Accumulator/Booster for providing the required polarized proton intensity and a system of spin rotators (Siberian snakes) to retain the polarization. The RHIC Spin Collaboration was formed and submitted a Letter of Intent to construct this polarized collider capability and utilize its physics opportunities. In this presentation, I will discuss the plans to upgrade the AGS, the proposed layout of the RHIC siberian snakes, and timetables. The physics focus is the measurement of the spin dependent parton distributions with such accessible probes including high p(t) jets, direct photons, and Drell Yan. The attainable sensitivities and the progress that has been reached in defining the detector requirements will be outlined.

  19. Polarized protons at RHIC

    SciTech Connect

    Makdisi, Y.

    1992-01-01

    The approval for construction of the Relativistic Heavy Ion Collider (RHIC) provides a potential opportunity to collide polarized proton beams at energies up to 500 GeV in the center of mass and high luminosities approaching 2 {times} 10{sup 32}/cm{sup 2}/sec. This capability is enhanced by the fact that the AGS has already accelerated polarized protons and relies on the newly completed Accumulator/Booster for providing the required polarized proton intensity and a system of spin rotators (Siberian snakes) to retain the polarization. The RHIC Spin Collaboration was formed and submitted a Letter of Intent to construct this polarized collider capability and utilize its physics opportunities. In this presentation, I will discuss the plans to upgrade the AGS, the proposed layout of the RHIC siberian snakes, and timetables. The physics focus is the measurement of the spin dependent parton distributions with such accessible probes including high p(t) jets, direct photons, and Drell Yan. The attainable sensitivities and the progress that has been reached in defining the detector requirements will be outlined.

  20. Pion, Kaon, Proton and Antiproton Production in Proton-Proton Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Blattnig, Steve R.

    2008-01-01

    Inclusive pion, kaon, proton, and antiproton production from proton-proton collisions is studied at a variety of proton energies. Various available parameterizations of Lorentz-invariant differential cross sections as a function of transverse momentum and rapidity are compared with experimental data. The Badhwar and Alper parameterizations are moderately satisfactory for charged pion production. The Badhwar parameterization provides the best fit for charged kaon production. For proton production, the Alper parameterization is best, and for antiproton production the Carey parameterization works best. However, no parameterization is able to fully account for all the data.

  1. Mass prediction of proton-rich nuclides with the Coulomb displacement energies in the relativistic point-coupling model

    NASA Astrophysics Data System (ADS)

    Sun, BaoHua; Zhao, PengWei; Meng, Jie

    2011-02-01

    The masses, one- and two-proton separation energies of proton-rich nuclei with Z = 20-55, are computed using the measured masses of mirror neutron-rich nuclei and the Coulomb displacement energies calculated from the relativistic point-coupling model. The implications for the proton drip lines, candidates for two-proton emitters, as well as the impact on the astrophysical rp-process are discussed.

  2. Proton-proton correlations observed in two-proton radioactivity of 94Ag.

    PubMed

    Mukha, Ivan; Roeckl, Ernst; Batist, Leonid; Blazhev, Andrey; Döring, Joachim; Grawe, Hubert; Grigorenko, Leonid; Huyse, Mark; Janas, Zenon; Kirchner, Reinhard; La Commara, Marco; Mazzocchi, Chiara; Tabor, Sam L; Van Duppen, Piet

    2006-01-19

    The stability and spontaneous decay of naturally occurring atomic nuclei have been much studied ever since Becquerel discovered natural radioactivity in 1896. In 1960, proton-rich nuclei with an odd or an even atomic number Z were predicted to decay through one- and two-proton radioactivity, respectively. The experimental observation of one-proton radioactivity was first reported in 1982, and two-proton radioactivity has now also been detected by experimentally studying the decay properties of 45Fe (refs 3, 4) and 54Zn (ref. 5). Here we report proton-proton correlations observed during the radioactive decay of a spinning long-lived state of the lightest known isotope of silver, 94Ag, which is known to undergo one-proton decay. We infer from these correlations that the long-lived state must also decay through simultaneous two-proton emission, making 94Ag the first nucleus to exhibit one- as well as two-proton radioactivity. We attribute the two-proton emission behaviour and the unexpectedly large probability for this decay mechanism to a very large deformation of the parent nucleus into a prolate (cigar-like) shape, which facilitates emission of protons either from the same or from opposite ends of the 'cigar'.

  3. Proton Degradation of Light-Emitting Diodes

    NASA Technical Reports Server (NTRS)

    Johnston, A. H.; Rax, B. G.; Selva, L. E.

    1997-01-01

    The severe degradation of optocouplers in space has been shown to be mainly due to proton displacement damage in the light-emitting diodes that are used within the optocouplers. However, a variety of LED technologies can be used in optocouplers and their sensitivity to proton displacement damage varies by about two orders of magnitude. Optocouplers are very simple hybrid devices, and the type of LED can be readily changed by the manufacturers with little cost impact. many optocoupler manufacturers purchase LEDs from outside sources with little knowledge or control of the manufacturing process used for the LED, leading to the possibility of very dramatic differences in radiation response (JPL has observed such differences for one type of optocoupler that is used in a hybrid power converter).

  4. Differential Cross Sections for Proton-Proton Elastic Scattering

    NASA Technical Reports Server (NTRS)

    Norman, Ryan B.; Dick, Frank; Norbury, John W.; Blattnig, Steve R.

    2009-01-01

    Proton-proton elastic scattering is investigated within the framework of the one pion exchange model in an attempt to model nucleon-nucleon interactions spanning the large range of energies important to cosmic ray shielding. A quantum field theoretic calculation is used to compute both differential and total cross sections. A scalar theory is then presented and compared to the one pion exchange model. The theoretical cross sections are compared to proton-proton scattering data to determine the validity of the models.

  5. Ultra-short laser-accelerated proton pulses have similar DNA-damaging effectiveness but produce less immediate nitroxidative stress than conventional proton beams

    PubMed Central

    Raschke, S.; Spickermann, S.; Toncian, T.; Swantusch, M.; Boeker, J.; Giesen, U.; Iliakis, G.; Willi, O.; Boege, F.

    2016-01-01

    Ultra-short proton pulses originating from laser-plasma accelerators can provide instantaneous dose rates at least 107-fold in excess of conventional, continuous proton beams. The impact of such extremely high proton dose rates on A549 human lung cancer cells was compared with conventionally accelerated protons and 90 keV X-rays. Between 0.2 and 2 Gy, the yield of DNA double strand breaks (foci of phosphorylated histone H2AX) was not significantly different between the two proton sources or proton irradiation and X-rays. Protein nitroxidation after 1 h judged by 3-nitrotyrosine generation was 2.5 and 5-fold higher in response to conventionally accelerated protons compared to laser-driven protons and X-rays, respectively. This difference was significant (p < 0.01) between 0.25 and 1 Gy. In conclusion, ultra-short proton pulses originating from laser-plasma accelerators have a similar DNA damaging potential as conventional proton beams, while inducing less immediate nitroxidative stress, which probably entails a distinct therapeutic potential. PMID:27578260

  6. Ultra-short laser-accelerated proton pulses have similar DNA-damaging effectiveness but produce less immediate nitroxidative stress than conventional proton beams

    NASA Astrophysics Data System (ADS)

    Raschke, S.; Spickermann, S.; Toncian, T.; Swantusch, M.; Boeker, J.; Giesen, U.; Iliakis, G.; Willi, O.; Boege, F.

    2016-08-01

    Ultra-short proton pulses originating from laser-plasma accelerators can provide instantaneous dose rates at least 107-fold in excess of conventional, continuous proton beams. The impact of such extremely high proton dose rates on A549 human lung cancer cells was compared with conventionally accelerated protons and 90 keV X-rays. Between 0.2 and 2 Gy, the yield of DNA double strand breaks (foci of phosphorylated histone H2AX) was not significantly different between the two proton sources or proton irradiation and X-rays. Protein nitroxidation after 1 h judged by 3-nitrotyrosine generation was 2.5 and 5-fold higher in response to conventionally accelerated protons compared to laser-driven protons and X-rays, respectively. This difference was significant (p < 0.01) between 0.25 and 1 Gy. In conclusion, ultra-short proton pulses originating from laser-plasma accelerators have a similar DNA damaging potential as conventional proton beams, while inducing less immediate nitroxidative stress, which probably entails a distinct therapeutic potential.

  7. Ultra-short laser-accelerated proton pulses have similar DNA-damaging effectiveness but produce less immediate nitroxidative stress than conventional proton beams.

    PubMed

    Raschke, S; Spickermann, S; Toncian, T; Swantusch, M; Boeker, J; Giesen, U; Iliakis, G; Willi, O; Boege, F

    2016-01-01

    Ultra-short proton pulses originating from laser-plasma accelerators can provide instantaneous dose rates at least 10(7)-fold in excess of conventional, continuous proton beams. The impact of such extremely high proton dose rates on A549 human lung cancer cells was compared with conventionally accelerated protons and 90 keV X-rays. Between 0.2 and 2 Gy, the yield of DNA double strand breaks (foci of phosphorylated histone H2AX) was not significantly different between the two proton sources or proton irradiation and X-rays. Protein nitroxidation after 1 h judged by 3-nitrotyrosine generation was 2.5 and 5-fold higher in response to conventionally accelerated protons compared to laser-driven protons and X-rays, respectively. This difference was significant (p < 0.01) between 0.25 and 1 Gy. In conclusion, ultra-short proton pulses originating from laser-plasma accelerators have a similar DNA damaging potential as conventional proton beams, while inducing less immediate nitroxidative stress, which probably entails a distinct therapeutic potential. PMID:27578260

  8. Proton irradiation and endometriosis

    SciTech Connect

    Wood, D.H.; Yochmowitz, M.G.; Salmon, Y.L.; Eason, R.L.; Boster, R.A.

    1983-08-01

    Female rhesus monkeys given single total-body exposures of protons of varying energies developed endometriosis at a frequency significantly higher than that of nonirradiated animals of the same age. The minimum latency period was 7 years after exposure. The doses and energies of the radiation received were within the range that could be received by an aircrew member in near-earth orbit during a random solar flare event, leading to the conclusion that endometriosis should be a consideration in assessing the risk of delayed radiation effects in female crewmembers.

  9. Physical and biological factors determining the effective proton range

    SciTech Connect

    Grün, Rebecca; Friedrich, Thomas; Krämer, Michael; Scholz, Michael; Zink, Klemens; Durante, Marco; Engenhart-Cabillic, Rita

    2013-11-15

    Purpose: Proton radiotherapy is rapidly becoming a standard treatment option for cancer. However, even though experimental data show an increase of the relative biological effectiveness (RBE) with depth, particularly at the distal end of the treatment field, a generic RBE of 1.1 is currently used in proton radiotherapy. This discrepancy might affect the effective penetration depth of the proton beam and thus the dose to the surrounding tissue and organs at risk. The purpose of this study was thus to analyze the impact of a tissue and dose dependent RBE of protons on the effective range of the proton beam in comparison to the range based on a generic RBE of 1.1.Methods: Factors influencing the biologically effective proton range were systematically analyzed by means of treatment planning studies using the Local Effect Model (LEM IV) and the treatment planning software TRiP98. Special emphasis was put on the comparison of passive and active range modulation techniques.Results: Beam energy, tissue type, and dose level significantly affected the biological extension of the treatment field at the distal edge. Up to 4 mm increased penetration depth as compared to the depth based on a constant RBE of 1.1. The extension of the biologically effective range strongly depends on the initial proton energy used for the most distal layer of the field and correlates with the width of the distal penumbra. Thus, the range extension, in general, was more pronounced for passive as compared to active range modulation systems, whereas the maximum RBE was higher for active systems.Conclusions: The analysis showed that the physical characteristics of the proton beam in terms of the width of the distal penumbra have a great impact on the RBE gradient and thus also the biologically effective penetration depth of the beam.

  10. Proton Upset Monte Carlo Simulation

    NASA Technical Reports Server (NTRS)

    O'Neill, Patrick M.; Kouba, Coy K.; Foster, Charles C.

    2009-01-01

    The Proton Upset Monte Carlo Simulation (PROPSET) program calculates the frequency of on-orbit upsets in computer chips (for given orbits such as Low Earth Orbit, Lunar Orbit, and the like) from proton bombardment based on the results of heavy ion testing alone. The software simulates the bombardment of modern microelectronic components (computer chips) with high-energy (.200 MeV) protons. The nuclear interaction of the proton with the silicon of the chip is modeled and nuclear fragments from this interaction are tracked using Monte Carlo techniques to produce statistically accurate predictions.

  11. Empirical Determination of Solar Proton Access to the Polar Atmosphere

    NASA Astrophysics Data System (ADS)

    Neal, Jason; Rodger, Craig; Green, Janet; Whittaker, Ian

    2014-05-01

    Violent expulsions on the Sun's surface release high energy solar protons that ultimately affect ionization levels and the local chemical composition in the upper atmosphere as well as High Frequency (HF) communication used by aircraft. The geomagnetic field screens the low altitude equatorial region, but these protons can access the atmosphere over the poles. The latitudes over which the solar protons can reach vary with geomagnetic indices such as Kp and Dst. In this study we use observations from Low Earth Orbit to determine the atmospheric access of solar protons and hence the flights paths most likely to be affected. Observations taken by up to six polar orbiting satellites during 15 solar proton events are analyzed. From this we determine 16,850 proton rigidity cutoff estimates across 3 energy channels. Empirical fits are undertaken to estimate the most likely behavior of the cutoff dependence with geomagnetic activity. We provide simple equations by which the geomagnetic latitude (spatial extent) at which the protons impact the atmosphere can be determined from a given Kp or Dst value. The variation found in the cutoff with Kp is similar to that used in existing operational models, although the changing Kp value is found to lead the variation in the cutoffs by ~3 hours .We also suggest a ~1-2° equatorward shift in latitude would provide greater accuracy. This solar proton access can be used as an input into coupled chemistry climate models and give the likely polar regions to be effected by Polar Cap Absorption (PCA) which causes HF radio 'blackout zones'. We find that a Kp predictive model can provide additional warning to the variation in proton cutoffs. Hence a prediction of the cutoff latitudes can be made ~3 hours to as much as 7 hours into the future, meeting suggested minimum planning times required by the aviation industry.

  12. [Proton imaging applications for proton therapy: state of the art].

    PubMed

    Amblard, R; Floquet, V; Angellier, G; Hannoun-Lévi, J M; Hérault, J

    2015-04-01

    Proton therapy allows a highly precise tumour volume irradiation with a low dose delivered to the healthy tissues. The steep dose gradients observed and the high treatment conformity require a precise knowledge of the proton range in matter and the target volume position relative to the beam. Thus, proton imaging allows an improvement of the treatment accuracy, and thereby, in treatment quality. Initially suggested in 1963, radiographic imaging with proton is still not used in clinical routine. The principal difficulty is the lack of spatial resolution, induced by the multiple Coulomb scattering of protons with nuclei. Moreover, its realization for all clinical locations requires relatively high energies that are previously not considered for clinical routine. Abandoned for some time in favor of X-ray technologies, research into new imaging methods using protons is back in the news because of the increase of proton radiation therapy centers in the world. This article exhibits a non-exhaustive state of the art in proton imaging.

  13. Proton in SRF Niobium

    SciTech Connect

    Wallace, John Paul

    2011-03-31

    Hydrogen is a difficult impurity to physically deal with in superconducting radio frequency (SRF) niobium, therefore, its properties in the metals should be well understood to allow the metal's superconducting properties to be optimized for minimum loss in the construction of resonant accelerator cavities. It is known that hydrogen is a paramagnetic impurity in niobium from NMR studies. This paramagnetism and its effect on superconducting properties are important to understand. To that end analytical induction measurements aimed at isolating the magnetic properties of hydrogen in SRF niobium are introduced along with optical reflection spectroscopy which is also sensitive to the presence of hydrogen. From the variety, magnitude and rapid kinetics found in the optical and magnetic properties of niobium contaminated with hydrogen forced a search for an atomic model. This yielded quantum mechanical description that correctly generates the activation energy for diffusion of the proton and its isotopes not only in niobium but the remaining metals for which data is available. This interpretation provides a frame work for understanding the individual and collective behavior of protons in metals.

  14. Berkeley Proton Linear Accelerator

    DOE R&D Accomplishments Database

    Alvarez, L. W.; Bradner, H.; Franck, J.; Gordon, H.; Gow, J. D.; Marshall, L. C.; Oppenheimer, F. F.; Panofsky, W. K. H.; Richman, C.; Woodyard, J. R.

    1953-10-13

    A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup 6} watts peak at 202.5 mc. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type.

  15. Emission of neutron-proton and proton-proton pairs in neutrino scattering

    NASA Astrophysics Data System (ADS)

    Ruiz Simo, I.; Amaro, J. E.; Barbaro, M. B.; De Pace, A.; Caballero, J. A.; Megias, G. D.; Donnelly, T. W.

    2016-11-01

    We use a recently developed model of relativistic meson-exchange currents to compute the neutron-proton and proton-proton yields in (νμ ,μ-) scattering from 12C in the 2p-2h channel. We compute the response functions and cross sections with the relativistic Fermi gas model for different kinematics from intermediate to high momentum transfers. We find a large contribution of neutron-proton configurations in the initial state, as compared to proton-proton pairs. In the case of charge-changing neutrino scattering the 2p-2h cross section of proton-proton emission (i.e., np in the initial state) is much larger than for neutron-proton emission (i.e., two neutrons in the initial state) by a (ω , q)-dependent factor. The different emission probabilities of distinct species of nucleon pairs are produced in our model only by meson-exchange currents, mainly by the Δ isobar current. We also analyze other effects including exchange contributions and the effect of the axial and vector currents.

  16. ACCELERATING POLARIZED PROTONS TO 250 GEV

    SciTech Connect

    BAI,M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; BEEBE-WANG, J.; ET AL.

    2007-06-25

    The Relativistic Heavy Ion Collider (RHIC) as the first high energy polarized proton collider was designed t o provide polarized proton collisions a t a maximum beam energy of 250 GeV. I t has been providing collisions a t a beam energy of 100 Gel' since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during the acceleration from injection to 100 GeV with careful control of the betatron tunes and the vertical orbit distortions. However, the intrinsic spin resonances beyond 100 GeV are about a factor of two stronger than those below 100 GeV? making it important t o examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were accelerated t o the record energy of 250 GeV in RHIC with a polarization of 46% measured a t top energy in 2006. The polarization measurement as a function of beam energy also shows some polarization loss around 136 GeV, the first strong intrinsic resonance above 100 GeV. This paper presents the results and discusses the sensitivity of the polarization survival t o orbit distortions.

  17. Probing neutron-proton dynamics by pions

    NASA Astrophysics Data System (ADS)

    Ikeno, Natsumi; Ono, Akira; Nara, Yasushi; Ohnishi, Akira

    2016-04-01

    In order to investigate the nuclear symmetry energy at high density, we study the pion production in central collisions of neutron-rich nuclei 132Sn+124Sn at 300 MeV/nucleon using a new approach that combines antisymmetrized molecular dynamics (AMD) and a hadronic cascade model (JAM). The dynamics of neutrons and protons is solved by AMD, and then pions and Δ resonances in the reaction process are handled by JAM. We see the mechanism by which the Δ resonance and pions are produced, reflecting the dynamics of neutrons and protons. We also investigate the impacts of cluster correlations as well as of the high-density symmetry energy on the nucleon dynamics and consequently on the pion ratio. We find that the Δ-/Δ++ production ratio agrees very well with the neutron-proton squared ratio (N/Z ) 2 in the high-density and high-momentum region. We show quantitatively that the Δ production ratio, and therefore (N/Z ) 2, are directly reflected in the π-/π+ ratio, with modification in the final stage of the reaction.

  18. Fragmentation pathways of protonated peptides.

    PubMed

    Paizs, Béla; Suhai, Sándor

    2005-01-01

    The fragmentation pathways of protonated peptides are reviewed in the present paper paying special attention to classification of the known fragmentation channels into a simple hierarchy defined according to the chemistry involved. It is shown that the 'mobile proton' model of peptide fragmentation can be used to understand the MS/MS spectra of protonated peptides only in a qualitative manner rationalizing differences observed for low-energy collision induced dissociation of peptide ions having or lacking a mobile proton. To overcome this limitation, a deeper understanding of the dissociation chemistry of protonated peptides is needed. To this end use of the 'pathways in competition' (PIC) model that involves a detailed energetic and kinetic characterization of the major peptide fragmentation pathways (PFPs) is proposed. The known PFPs are described in detail including all the pre-dissociation, dissociation, and post-dissociation events. It is our hope that studies to further extend PIC will lead to semi-quantative understanding of the MS/MS spectra of protonated peptides which could be used to develop refined bioinformatics algorithms for MS/MS based proteomics. Experimental and computational data on the fragmentation of protonated peptides are reevaluated from the point of view of the PIC model considering the mechanism, energetics, and kinetics of the major PFPs. Evidence proving semi-quantitative predictability of some of the ion intensity relationships (IIRs) of the MS/MS spectra of protonated peptides is presented. PMID:15389847

  19. Proton Collimators for Fusion Reactors

    NASA Technical Reports Server (NTRS)

    Miley, George H.; Momota, Hiromu

    2003-01-01

    Proton collimators have been proposed for incorporation into inertial-electrostatic-confinement (IEC) fusion reactors. Such reactors have been envisioned as thrusters and sources of electric power for spacecraft and as sources of energetic protons in commercial ion-beam applications.

  20. Feasibility of pulsed proton acoustics for 3D dosimetry

    NASA Astrophysics Data System (ADS)

    Alsanea, Fahed M.

    PW and Delta t for the same number of protons (1.8x107) demonstrated that compressing the protons in a shorter period of time significantly increased the thermoacoustic signal and thus sensitivity. This study demonstrates that computed tomographic scanner based on ionizing radiation induced acoustics can be used to verify dose distribution and proton range. Realizing this technology into the clinic will have significant impact on treatment verification during particle beam therapy and image guided techniques.

  1. Proton therapy for pancreatic cancer

    PubMed Central

    Nichols, Romaine C; Huh, Soon; Li, Zuofeng; Rutenberg, Michael

    2015-01-01

    Radiotherapy is commonly offered to patients with pancreatic malignancies although its ultimate utility is compromised since the pancreas is surrounded by exquisitely radiosensitive normal tissues, such as the duodenum, stomach, jejunum, liver, and kidneys. Proton radiotherapy can be used to create dose distributions that conform to tumor targets with significant normal tissue sparing. Because of this, protons appear to represent a superior modality for radiotherapy delivery to patients with unresectable tumors and those receiving postoperative radiotherapy. A particularly exciting opportunity for protons also exists for patients with resectable and marginally resectable disease. In this paper, we review the current literature on proton therapy for pancreatic cancer and discuss scenarios wherein the improvement in the therapeutic index with protons may have the potential to change the management paradigm for this malignancy. PMID:26380057

  2. An Examination of Proton Charge Radius Extractions from e–p Scattering Data

    SciTech Connect

    Arrington, John

    2015-09-15

    A detailed examination of issues associated with proton radius extractions from elastic electron–proton scattering experiments is presented. Sources of systematic uncertainty and model dependence in the extractions are discussed, with an emphasis on how these may impact the proton charge and magnetic radii. A comparison of recent Mainz data to previous world data is presented, highlighting the difference in treatment of systematic uncertainties as well as tension between different data sets. We find several issues that suggest that larger uncertainties than previously quoted may be appropriate, but do not find any corrections which would resolve the proton radius puzzle.

  3. The proton (nuclear) microprobe

    NASA Astrophysics Data System (ADS)

    Legge, G. J. F.

    1989-04-01

    The scanning proton microprobe (SPMP) is closely related to the scanning electron microprobe (SEMP) or scanning electron microscope (SEM) with X-ray detector. Though the much greater elemental sensitivity of the SPMP is inherent in the physics, the generally inferior spatial resolution of the SPMP is not inherent and big improvements are possible, As its alternative name would imply, the SPMP is often used with heavier particle beams and with nuclear rather than atomic reactions. Its versatility and quantitative accuracy have justified greater instrumentation and computer power than that associated with other microprobes. It is fast becoming an industrially and commercially important instrument and there are few fields of scientific research in which it has not played a part. Notable contributions have been made in biology, medicine, agriculture, semiconductors, geology, mineralogy, extractive metallurgy, new materials, archaeology, forensic science, catalysis, industrial problems and reactor technology.

  4. Ion-proton pulsars

    NASA Astrophysics Data System (ADS)

    Jones, P. B.

    2016-07-01

    Evidence derived with minimal assumptions from existing published observations is presented to show that an ion-proton plasma is the source of radio-frequency emission in millisecond and in normal isolated pulsars. There is no primary involvement of electron-positron pairs. This conclusion has also been reached by studies of the plasma composition based on well-established particle-physics processes in neutron stars with positive polar-cap corotational charge density. This work has been published in a series of papers which are also summarized here. It is now confirmed by simple analyses of the observed radio-frequency characteristics, and its implications for the further study of neutron stars are outlined.

  5. Star tracker operation in a high density proton field

    NASA Astrophysics Data System (ADS)

    Miklus, Kenneth J.; Kissh, Frank; Flynn, David J.

    1993-02-01

    Algorithms that reject transient signals due to proton effects on charge coupled device (CCD) sensors have been implemented in the HDOS ASTRA-l Star Trackers to be flown on the TOPEX mission scheduled for launch in July 1992. A unique technique for simulating a proton-rich environment to test trackers is described, as well as the test results obtained. Solar flares or an orbit that passes through the South Atlantic Anomaly can subject the vehicle to very high proton flux levels. There are three ways in which spurious proton generated signals can impact tracker performance: the many false signals can prevent or extend the time to acquire a star; a proton-generated signal can compromise the accuracy of the star's reported magnitude and position; and the tracked star can be lost, requiring reacquisition. Tests simulating a proton-rich environment were performed on two ASTRA-1 Star Trackers utilizing these new algorithms. There were no false acquisitions, no lost stars, and a significant reduction in reported position errors due to these improvements.

  6. Star tracker operation in a high density proton field

    NASA Technical Reports Server (NTRS)

    Miklus, Kenneth J.; Kissh, Frank; Flynn, David J.

    1993-01-01

    Algorithms that reject transient signals due to proton effects on charge coupled device (CCD) sensors have been implemented in the HDOS ASTRA-l Star Trackers to be flown on the TOPEX mission scheduled for launch in July 1992. A unique technique for simulating a proton-rich environment to test trackers is described, as well as the test results obtained. Solar flares or an orbit that passes through the South Atlantic Anomaly can subject the vehicle to very high proton flux levels. There are three ways in which spurious proton generated signals can impact tracker performance: the many false signals can prevent or extend the time to acquire a star; a proton-generated signal can compromise the accuracy of the star's reported magnitude and position; and the tracked star can be lost, requiring reacquisition. Tests simulating a proton-rich environment were performed on two ASTRA-1 Star Trackers utilizing these new algorithms. There were no false acquisitions, no lost stars, and a significant reduction in reported position errors due to these improvements.

  7. A Dosimetric Comparison of Proton and Intensity-Modulated Photon Radiotherapy for Pediatric Parameningeal Rhabdomyosarcomas

    SciTech Connect

    Kozak, Kevin R.; Adams, Judith; Krejcarek, Stephanie J.; Tarbell, Nancy J.; Yock, Torunn I.

    2009-05-01

    Purpose: We compared tumor and normal tissue dosimetry of proton radiation therapy with intensity-modulated radiation therapy (IMRT) for pediatric parameningeal rhabdomyosarcomas (PRMS). Methods and Materials: To quantify dosimetric differences between contemporary proton and photon treatment for pediatric PRMS, proton beam plans were compared with IMRT plans. Ten patients treated with proton radiation therapy at Massachusetts General Hospital had IMRT plans generated. To facilitate dosimetric comparisons, clinical target volumes and normal tissue volumes were held constant. Plans were optimized for target volume coverage and normal tissue sparing. Results: Proton and IMRT plans provided acceptable and comparable target volume coverage, with at least 99% of the CTV receiving 95% of the prescribed dose in all cases. Improved dose conformality provided by proton therapy resulted in significant sparing of all examined normal tissues except for ipsilateral cochlea and mastoid; ipsilateral parotid gland sparing was of borderline statistical significance (p = 0.05). More profound sparing of contralateral structures by protons resulted in greater dose asymmetry between ipsilateral and contralateral retina, optic nerves, cochlea, and mastoids; dose asymmetry between ipsilateral and contralateral parotids was of borderline statistical significance (p = 0.05). Conclusions: For pediatric PRMS, superior normal tissue sparing is achieved with proton radiation therapy compared with IMRT. Because of enhanced conformality, proton plans also demonstrate greater normal tissue dose distribution asymmetry. Longitudinal studies assessing the impact of proton radiotherapy and IMRT on normal tissue function and growth symmetry are necessary to define the clinical consequences of these differences.

  8. RHIC Polarized proton operation

    SciTech Connect

    Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D'Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

    2011-03-28

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above

  9. Where is the proton's spin

    SciTech Connect

    Close, F.E.

    1988-01-01

    There has been much recent excitement arising from the claim by the EMC collaboration that none of the proton's spin is carried by quarks. There are many textbooks, including those written by some members of this audience, which assert that the proton's spin is carried by quarks. I will review the history of deep inelastic scattering of polarized leptons from polarized protons, culminating in this most recent dramatic claim. I will show that, for the last decade, data have appeared consistent with predictions of the quark model and highlight what the new and potentially exciting data are. I will conclude with suggestions for the future. 33 refs.

  10. Eta Meson Production in Proton-Proton and Nuclear Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Dick, Frank

    2008-01-01

    Total cross sections for eta meson production in proton - proton collisions are calculated. The eta meson is mainly produced via decay of the excited nucleon resonance at 1535 MeV. A scalar quantum field theory is used to calculate cross sections, which also include resonance decay. Comparison between theory and experiment is problematic near threshold when resonance decay is not included. When the decay is included, the comparison between theory and experiment is much better.

  11. High intensity proton synchrotrons

    NASA Astrophysics Data System (ADS)

    Craddock, M. K.

    1986-10-01

    Strong initiatives are being pursued in a number of countries for the construction of ``kaon factory'' synchrotrons capable of producing 100 times more intense proton beams than those available now from machines such as the Brookhaven AGS and CERN PS. Such machines would yield equivalent increases in the fluxes of secondary particles (kaons, pions, muons, antiprotons, hyperons and neutrinos of all varieties)—or cleaner beams for a smaller increase in flux—opening new avenues to various fundamental questions in both particle and nuclear physics. Major areas of investigation would be rare decay modes, CP violation, meson and hadron spectroscopy, antinucleon interactions, neutrino scattering and oscillations, and hypernuclear properties. Experience with the pion factories has already shown how high beam intensities make it possible to explore the ``precision frontier'' with results complementary to those achievable at the ``energy frontier''. This paper will describe proposals for upgrading and AGS and for building kaon factories in Canada, Europe, Japan and the United States, emphasizing the novel aspects of accelerator design required to achieve the desired performance (typically 100 μA at 30 GeV).

  12. Proton-Coupled Electron Transfer

    SciTech Connect

    Weinberg, Dave; Gagliardi, Christopher J.; Hull, Jonathan F; Murphy, Christine Fecenko; Kent, Caleb A.; Westlake, Brittany C.; Paul, Amit; Ess, Daniel H; McCafferty, Dewey Granville; Meyer, Thomas J

    2012-07-11

    Proton-Coupled Electron Transfer (PCET) describes reactions in which there is a change in both electron and proton content between reactants and products. It originates from the influence of changes in electron content on acid-base properties and provides a molecular-level basis for energy transduction between proton transfer and electron transfer. Coupled electron-proton transfer or EPT is defined as an elementary step in which electrons and protons transfer from different orbitals on the donor to different orbitals on the acceptor. There is (usually) a clear distinction between EPT and H-atom transfer (HAT) or hydride transfer, in which the transferring electrons and proton come from the same bond. Hybrid mechanisms exist in which the elementary steps are different for the reaction partners. EPT pathways such as PhO•/PhOH exchange have much in common with HAT pathways in that electronic coupling is significant, comparable to the reorganization energy with H{sub DA} ~ λ. Multiple-Site Electron-Proton Transfer (MS-EPT) is an elementary step in which an electron-proton donor transfers electrons and protons to different acceptors, or an electron-proton acceptor accepts electrons and protons from different donors. It exploits the long-range nature of electron transfer while providing for the short-range nature of proton transfer. A variety of EPT pathways exist, creating a taxonomy based on what is transferred, e.g., 1e-/2H+ MS-EPT. PCET achieves “redox potential leveling” between sequential couples and the buildup of multiple redox equivalents, which is of importance in multielectron catalysis. There are many examples of PCET and pH-dependent redox behavior in metal complexes, in organic and biological molecules, in excited states, and on surfaces. Changes in pH can be used to induce electron transfer through films and over long distances in molecules. Changes in pH, induced by local electron transfer, create pH gradients and a driving

  13. Interplanetary Proton Model: JPL 1991

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Spitale, G.; Wang, J.

    1993-01-01

    This study was carried out to increase the acuracy and energy range of predictive models of interplanetary proton fluences. Such an estimate is often needed when spacecraft spend a signigicant amount of time in the interplanetary environmnet.

  14. POLARIZED PROTON COLLISIONS AT RHIC.

    SciTech Connect

    BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; ET AL.

    2005-05-16

    The Relativistic Heavy Ion Collider provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC. In 2002, polarized proton beams were first accelerated to 100 GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. Optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limited conditions are reported.

  15. Parametric Model for Astrophysical Proton-Proton Interactions and Applications

    SciTech Connect

    Karlsson, Niklas

    2007-01-01

    Observations of gamma-rays have been made from celestial sources such as active galaxies, gamma-ray bursts and supernova remnants as well as the Galactic ridge. The study of gamma rays can provide information about production mechanisms and cosmic-ray acceleration. In the high-energy regime, one of the dominant mechanisms for gamma-ray production is the decay of neutral pions produced in interactions of ultra-relativistic cosmic-ray nuclei and interstellar matter. Presented here is a parametric model for calculations of inclusive cross sections and transverse momentum distributions for secondary particles--gamma rays, e±, ve, $\\bar{v}$e, vμ and $\\bar{μ}$e--produced in proton-proton interactions. This parametric model is derived on the proton-proton interaction model proposed by Kamae et al.; it includes the diffraction dissociation process, Feynman-scaling violation and the logarithmically rising inelastic proton-proton cross section. To improve fidelity to experimental data for lower energies, two baryon resonance excitation processes were added; one representing the Δ(1232) and the other multiple resonances with masses around 1600 MeV/c2. The model predicts the power-law spectral index for all secondary particle to be about 0.05 lower in absolute value than that of the incident proton and their inclusive cross sections to be larger than those predicted by previous models based on the Feynman-scaling hypothesis. The applications of the presented model in astrophysics are plentiful. It has been implemented into the Galprop code to calculate the contribution due to pion decays in the Galactic plane. The model has also been used to estimate the cosmic-ray flux in the Large Magellanic Cloud based on HI, CO and gamma-ray observations. The transverse momentum distributions enable calculations when the proton distribution is anisotropic. It is shown that the gamma-ray spectrum and flux due to a

  16. Proton driver power supply system

    SciTech Connect

    C. Jach and D. Wolff

    2002-06-03

    This paper describes magnet power supply system for a proposed Proton Driver at Fermilab. The magnet power supply system consists of resonant dipole/quadrupole power supply system, quadrupole tracking, dipole correction (horizontal and vertical) and sextupole power supply systems. This paper also describes preliminary design of the power distribution system supplying 13.8 kV power to all proton Driver electrical systems.

  17. Voltage-gated Proton Channels

    PubMed Central

    DeCoursey, Thomas E.

    2014-01-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

  18. Recent Solar-Proton Fluxes

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.

    2005-01-01

    The event-integrated fluences of energetic solar protons up to 2004 at the Earth have been determined and compared to previous data. The current solar cycle has been very active, and very large fluxes of solar protons have been observed that have had serious effects in the solar system and will have produced many radionuclides in the surfaces of meteorites. Such huge events are not expected again until about 2008 or 2009.

  19. Understanding the proton's spin structure

    SciTech Connect

    Fred Myhrer; Thomas, Anthony W.

    2010-02-01

    We discuss the tremendous progress that has been towards an understanding of how the spin of the proton is distributed on its quark and gluon constituents. This is a problem that began in earnest twenty years ago with the discovery of the proton "spin crisis" by the European Muon Collaboration. The discoveries prompted by that original work have given us unprecedented insight into the amount of spin carried by polarized gluons and the orbital angular momentum of the quarks.

  20. Voltage-gated proton channels.

    PubMed

    Decoursey, Thomas E

    2012-04-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely, the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance approximately 10(3) times smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn(2+) (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B-lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H(+) for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens.

  1. High intensity protons in RHIC

    SciTech Connect

    Montag, C.; Ahrens, L.; Blaskiewicz, M.; Brennan, J. M.; Drees, K. A.; Fischer, W.; Huang, H.; Minty, M.; Robert-Demolaize, G.; Thieberger, P.; Yip, K.

    2012-01-05

    During the 2012 summer shutdown a pair of electron lenses will be installed in RHIC, allowing the beam-beam parameter to be increased by roughly 50 percent. To realize the corresponding luminosity increase bunch intensities have to be increased by 50 percent, to 2.5 {center_dot} 10{sup 11} protons per bunch. We list the various RHIC subsystems that are most affected by this increase, and propose beam studies to ensure their readiness. The proton luminosity in RHIC is presently limited by the beam-beam effect. To overcome this limitation, electron lenses will be installed in IR10. With the help of these devices, the headon beam-beam kick experienced during proton-proton collisions will be partially compensated, allowing for a larger beam-beam tuneshift at these collision points, and therefore increasing the luminosity. This will be accomplished by increasing the proton bunch intensity from the presently achieved 1.65 {center_dot} 10{sup 11} protons per bunch in 109 bunches per beam to 2.5 {center_dot} 10{sup 11}, thus roughly doubling the luminosity. In a further upgrade we aim for bunch intensities up to 3 {center_dot} 10{sup 11} protons per bunch. With RHIC originally being designed for a bunch intensity of 1 {center_dot} 10{sup 11} protons per bunch in 56 bunches, this six-fold increase in the total beam intensity by far exceeds the design parameters of the machine, and therefore potentially of its subsystems. In this note, we present a list of major subsystems that are of potential concern regarding this intensity upgrade, show their demonstrated performance at present intensities, and propose measures and beam experiments to study their readiness for the projected future intensities.

  2. Proton therapy for cancer treatment.

    PubMed

    Dinesh Mayani, Devanshi

    2011-09-01

    Proton beam therapy is the latest advancement in the treatment of various types of cancer. It is a precise form of radiotherapy. It uses a beam of protons to target the cancer cells and destroys them. It scores high on precision and effectiveness when compared to other conventional cancer treatments like surgery, chemotherapy and xray radiotherapy. Proton beam therapy destroys the cancerous cells without harming the healthy cells. Thus it considerably reduces the side-effects that accompany conventional cancer treatments. Supporters say the technology allows physicians to treat a broad spectrum of cancers with few adverse effects, while more precisely targeting tumor cells with higher doses of radiation. Detractors say proton beam therapy is hugely expensive and has not been shown to be superior to conventional radiation treatment. With proton beam therapy, physicians use a cyclotron to accelerate protons and fire them directly into tumor cells with submillimeter precision. Because healthy tissue is largely spared, oncologists can, in theory, deliver much higher doses of radiation, while improving local control and reducing the risk for recurrence and morbidities.

  3. Generation of proton aurora by magnetosonic waves

    PubMed Central

    Xiao, Fuliang; Zong, Qiugang; Wang, Yongfu; He, Zhaoguo; Su, Zhenpeng; Yang, Chang; Zhou, Qinghua

    2014-01-01

    Earth's proton aurora occurs over a broad MLT region and is produced by the precipitation of low-energy (2–10 keV) plasmasheet protons. Proton precipitation can alter chemical compositions of the atmosphere, linking solar activity with global climate variability. Previous studies proposed that electromagnetic ion cyclotron waves can resonate with protons, producing proton scattering precipitation. A long-outstanding question still remains whether there is another mechanism responsible for the proton aurora. Here, by performing satellite data analysis and diffusion equation calculations, we show that fast magnetosonic waves can produce trapped proton scattering that yields proton aurora. This provides a new insight into the mechanism of proton aurora. Furthermore, a ray-tracing study demonstrates that magnetosonic wave propagates over a broad MLT region, consistent with the global distribution of proton aurora. PMID:24898626

  4. Development of Proton Computed Tomography for Applications in Proton Therapy

    SciTech Connect

    Bashkirov, Vladimir; Schulte, Reinhard; Coutrakon, George; Erdelyi, Bela; Wong, Kent; Sadrozinski, Hartmut; Penfold, Scott; Rosenfeld, Anatoly; McAllister, Scott; Schubert, Keith

    2009-03-10

    Determination of the Bragg peak position in proton therapy requires accurate knowledge of the electron density and ratio of effective atomic number and mass (Z/A) of the body tissues traversed. While the Z/A ratio is fairly constant for human tissues, the density of tissues varies significantly. One possibility to obtain accurate electron density information of tissues is to use protons of sufficient energy to penetrate the patient and measure their energy loss. From these transmission measurements, it is possible to reconstruct a three-dimensional map of electron densities using algebraic techniques. The interest in proton computed tomography (pCT) has considerably increased in recent years due to the more common use of proton accelerators for cancer treatment world-wide and a modern design concept based on current high-energy physics technology has been suggested. This contribution gives a status update on the pCT project carried out by the pCT Collaboration, a group of institutions sharing interest and expertise in the development of pCT. We will present updated imaging data obtained with a small pCT prototype developed in collaboration with the Santa Cruz Institute of Particle Physics and installed on the proton research beam line at Loma Linda University Medical Center. We will discuss hardware decisions regarding the next-generation pCT scanner, which will permit scanning of head-sized objects. Progress has also been made in the formulation of the most likely path of protons through an object and parallelizable iterative reconstruction algorithms that can be implemented on general-purpose commodity graphics processing units. Finally, we will present simulation studies for utilizing pCT technology for on-line proton dose verification and tumor imaging with positron emission tomography (PET)

  5. Nonadiabatic rate constants for proton transfer and proton-coupled electron transfer reactions in solution: Effects of quadratic term in the vibronic coupling expansion.

    PubMed

    Soudackov, Alexander V; Hammes-Schiffer, Sharon

    2015-11-21

    Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton

  6. Nonadiabatic rate constants for proton transfer and proton-coupled electron transfer reactions in solution: Effects of quadratic term in the vibronic coupling expansion

    SciTech Connect

    Soudackov, Alexander V.; Hammes-Schiffer, Sharon

    2015-11-21

    Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton

  7. Nonadiabatic rate constants for proton transfer and proton-coupled electron transfer reactions in solution: Effects of quadratic term in the vibronic coupling expansion.

    PubMed

    Soudackov, Alexander V; Hammes-Schiffer, Sharon

    2015-11-21

    Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton

  8. Sparse-view proton computed tomography using modulated proton beams

    SciTech Connect

    Lee, Jiseoc; Kim, Changhwan; Cho, Seungryong; Min, Byungjun; Kwak, Jungwon; Park, Seyjoon; Lee, Se Byeong; Park, Sungyong

    2015-02-15

    Purpose: Proton imaging that uses a modulated proton beam and an intensity detector allows a relatively fast image acquisition compared to the imaging approach based on a trajectory tracking detector. In addition, it requires a relatively simple implementation in a conventional proton therapy equipment. The model of geometric straight ray assumed in conventional computed tomography (CT) image reconstruction is however challenged by multiple-Coulomb scattering and energy straggling in the proton imaging. Radiation dose to the patient is another important issue that has to be taken care of for practical applications. In this work, the authors have investigated iterative image reconstructions after a deconvolution of the sparsely view-sampled data to address these issues in proton CT. Methods: Proton projection images were acquired using the modulated proton beams and the EBT2 film as an intensity detector. Four electron-density cylinders representing normal soft tissues and bone were used as imaged object and scanned at 40 views that are equally separated over 360°. Digitized film images were converted to water-equivalent thickness by use of an empirically derived conversion curve. For improving the image quality, a deconvolution-based image deblurring with an empirically acquired point spread function was employed. They have implemented iterative image reconstruction algorithms such as adaptive steepest descent-projection onto convex sets (ASD-POCS), superiorization method–projection onto convex sets (SM-POCS), superiorization method–expectation maximization (SM-EM), and expectation maximization-total variation minimization (EM-TV). Performance of the four image reconstruction algorithms was analyzed and compared quantitatively via contrast-to-noise ratio (CNR) and root-mean-square-error (RMSE). Results: Objects of higher electron density have been reconstructed more accurately than those of lower density objects. The bone, for example, has been reconstructed

  9. Proton Therapy Facility Planning From a Clinical and Operational Model.

    PubMed

    Das, Indra J; Moskvin, Vadim P; Zhao, Qingya; Cheng, Chee-Wai; Johnstone, Peter A

    2015-10-01

    This paper provides a model for planning a new proton therapy center based on clinical data, referral pattern, beam utilization and technical considerations. The patient-specific data for the depth of targets from skin in each beam angle were reviewed at our center providing megavoltage photon external beam and proton beam therapy respectively. Further, data on insurance providers, disease sites, treatment depths, snout size and the beam angle utilization from the patients treated at our proton facility were collected and analyzed for their utilization and their impact on the facility cost. The most common disease sites treated at our center are head and neck, brain, sarcoma and pediatric malignancies. From this analysis, it is shown that the tumor depth from skin surface has a bimodal distribution (peak at 12 and 26 cm) that has significant impact on the maximum proton energy, requiring the energy in the range of 130-230 MeV. The choice of beam angles also showed a distinct pattern: mainly at 90° and 270°; this indicates that the number of gantries may be minimized. Snout usage data showed that 70% of the patients are treated with 10 cm snouts. The cost of proton beam therapy depends largely on the type of machine, maximum beam energy and the choice of gantry versus fixed beam line. Our study indicates that for a 4-room center, only two gantry rooms could be needed at the present pattern of the patient cohorts, thus significantly reducing the initial capital cost. In the USA, 95% and 100% of patients can be treated with 200 and 230 MeV proton beam respectively. Use of multi-leaf collimators and pencil beam scanning may further reduce the operational cost of the facility.

  10. Proton Therapy Facility Planning From a Clinical and Operational Model.

    PubMed

    Das, Indra J; Moskvin, Vadim P; Zhao, Qingya; Cheng, Chee-Wai; Johnstone, Peter A

    2015-10-01

    This paper provides a model for planning a new proton therapy center based on clinical data, referral pattern, beam utilization and technical considerations. The patient-specific data for the depth of targets from skin in each beam angle were reviewed at our center providing megavoltage photon external beam and proton beam therapy respectively. Further, data on insurance providers, disease sites, treatment depths, snout size and the beam angle utilization from the patients treated at our proton facility were collected and analyzed for their utilization and their impact on the facility cost. The most common disease sites treated at our center are head and neck, brain, sarcoma and pediatric malignancies. From this analysis, it is shown that the tumor depth from skin surface has a bimodal distribution (peak at 12 and 26 cm) that has significant impact on the maximum proton energy, requiring the energy in the range of 130-230 MeV. The choice of beam angles also showed a distinct pattern: mainly at 90° and 270°; this indicates that the number of gantries may be minimized. Snout usage data showed that 70% of the patients are treated with 10 cm snouts. The cost of proton beam therapy depends largely on the type of machine, maximum beam energy and the choice of gantry versus fixed beam line. Our study indicates that for a 4-room center, only two gantry rooms could be needed at the present pattern of the patient cohorts, thus significantly reducing the initial capital cost. In the USA, 95% and 100% of patients can be treated with 200 and 230 MeV proton beam respectively. Use of multi-leaf collimators and pencil beam scanning may further reduce the operational cost of the facility. PMID:24988058

  11. Fast proton conducting glasses: Creation by proton implantation and a requirement for fast proton conduction

    NASA Astrophysics Data System (ADS)

    Hosono, Hideo; Kawamura, Ken-ichi; Kawazoe, Hiroshi; Matsunami, Noriaki; Abe, Yoshihiro

    1997-02-01

    Fast proton conducting glasses have been obtained in Mg(PO3)2 glasses by implantation of protons at 120 keV to a fluence of 1×1018 cm-2. The dc conductivity and the activation energy of the conduction in the implanted glasses are 5×10-4 s cm-1 at room temperature and 0.18 eV, respectively. No fast proton conduction was observed for H+-implanted SiO2 and Ca(PO3)2 glasses. Infrared absorption spectra revealed that implanted protons are present in the form of X-OH (X=Si or P) in SiO2 and Ca(PO3)2 glasses implanted with H+ ions to 1×1018 cm-2, but exist as POH groups and molecular water H2O in Mg(PO3)2 glasses. A quantitative discussion on the proton conductivity led to the conclusion that the coexistence of acidic groups such as POH and molecular water H2O is a structural requirement for the emergence of fast proton conduction in oxide glasses. The formation of H2O in Mg(PO3)2 was understood by considering its thermodynamic stability over SiO2 and Ca(PO3)2 glasses.

  12. The Proton Form Factor Ratio Measurements at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Punjabi, Vina; Perdrisat, Charles F.

    2014-03-01

    The ratio of the proton form factors, GEp/GMp, has been measured from Q2 of 0.5 GeV2 to 8.5 GeV2, at the Jefferson Laboratory, using the polarization transfer method. This ratio is extracted directly from the measured ratio of the transverse and longitudinal polarization components of the recoiling proton in elastic electron-proton scattering. The discovery that the proton form factor ratio measured in these experiments decreases approximately linearly with four-momentum transfer, Q2, for values above ≈ 1 GeV2, is one of the most significant results to come out of JLab. These results have had a large impact on progress in hadronic physics; and have required a significant rethinking of nucleon structure. There is an approved experiment at JLab, GEp(5), to continue the ratio measurements to 12 GeV2. A dedicated experimental setup, the Super Bigbite Spectrometer (SBS), will be built for this purpose. In this paper, the present status of the proton elastic electromagnetic form factors and a number of theoretical approaches to describe nucleon form factors will be discussed.

  13. Ultrafast laser-driven proton sources and dynamic proton imaging

    SciTech Connect

    Nickles, Peter V.; Schnuerer, Matthias; Sokollik, Thomas; Ter-Avetisyan, Sargis; Sandner, Wolfgang; Amin, Munib; Toncian, Toma; Willi, Oswald; Andreev, Alexander

    2008-07-15

    Ion bursts, accelerated by an ultrafast (40 fs) laser-assisted target normal sheath acceleration mechanism, can be adjusted so as to deliver a nearly pure proton beam. Such laser-driven proton bursts have predominantly a low transverse emittance and a broad kinetic spectrum suitable for continuous probing of the temporal evolution of spatially extended electric fields that arise after laser irradiation of thin foils. Fields with a strength of up to 10{sup 10} V/m were measured with a new streaklike proton deflectometry setup. The data show the temporal and spatial evolution of electric fields that are due to target charge-up and ion-front expansion following intense laser-target interaction at intensities of 10{sup 17}-10{sup 18} W/cm{sup 2}. Measurement of the field evolution is important to gain further insight into lateral electron-transport processes and the influence of field dynamics on ion beam properties.

  14. Proton-proton Scattering Above 3 GeV/c

    SciTech Connect

    A. Sibirtsev, J. Haidenbauer, H.-W. Hammer S. Krewald ,Ulf-G. Meissner

    2010-01-01

    A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter A{sub NN} is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3 GeV/c to 50 GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the {rho}, {omega}, f{sub 2}, and a{sub 2} trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model.

  15. Measurement of the Wolfenstein parameters for proton-proton and proton-neutron scattering at 500 MeV

    SciTech Connect

    Marshall, J.A.

    1984-07-01

    Using liquid hydrogen and liquid deuterium targets respectively, forward angle (ten degrees to sixty degrees in the center of Mass) free proton-proton and quasielastic proton-proton and proton-neutron triple scattering data at 500 MeV have been obtained using the high resolution spectrometer at the Los Alamos Meson Physics Facility. The data are in reasonable agreement with recent predictions from phase shift analyses, indicating that the proton-nucleon scattering amplitudes are fairly well determined at 500 MeV. 32 references.

  16. The Structure of the Proton

    DOE R&D Accomplishments Database

    Chambers, E. E.; Hofstadter, R.

    1956-04-01

    The structure and size of the proton have been studied by means of the methods of high-energy electron scattering. The elastic scattering of electrons from protons in polyethylene has been investigated at the following energies in the laboratory system: 200, 300, 400, 500, 550 Mev. The range of laboratory angles examined has been 30 degrees to 135 degrees. At the largest angles and the highest energy, the cross section for scattering shows a deviation below that expected from a point proton by a factor of about nine. The magnitude and variation with angle of the deviations determine a structure factor for the proton, and thereby determine the size and shape of the charge and magnetic-moment distributions within the proton. An interpretation, consistent at all energies and angles and agreeing with earlier results from this laboratory, fixes the rms radius at 0.77 {plus or minus} 0.10 x 10{sup -13} cm for each of the charge and moment distributions. The shape of the density function is not far from a Gaussian with rms radius 0.70 x 10{sup -13} cm or an exponential with rms radius 0.80 x 10 {sup -13} cm. An equivalent interpretation of the experiments would ascribe the apparent size to a breakdown of the Coulomb law and the conventional theory of electromagnetism.

  17. The Spin of the Proton

    SciTech Connect

    Thomas, Anthony

    2008-07-01

    doi: http://dx.doi.org/10.1016/j.ppnp.2007.12.039
    The twenty years since the announcement of the proton spin crisis by the European Muon Collaboration has seen tremendous progress in our knowledge of the distribution of spin within the proton. The problem is reviewed, beginning with the original data and the suggestion that polarized gluons may play a crucial role in resolving the problem through the U(1) axial anomaly. The discussion continues to the present day where not only have strong limits have been placed on the amount of polarized glue in the proton but the experimental determination of the spin content has become much more precise. It is now clear that the origin of the discrepancy between experiment and the naive expectation of the fraction of spin carried by the quarks and anti-quarks in the proton lies in the non-perturabtive structure of the proton. We explain how the features expected in a modern, relativistic and chirally symmetric description of nucleon str

  18. Polarized proton beams in RHIC

    SciTech Connect

    Zelenski, A.

    2010-10-04

    The polarized beam for RHIC is produced in the optically-pumped polarized H{sup -} ion source and then accelerated in Linac to 200 MeV for strip-injection to Booster and further accelerated 24.3 GeV in AGS for injection in RHIC. In 2009 Run polarized protons was successfully accelerated to 250 GeV beam energy. The beam polarization of about 60% at 100 GeV beam energy and 36-42% at 250 GeV beam energy was measured with the H-jet and p-Carbon CNI polarimeters. The gluon contribution to the proton spin was studied in collisions of longitudinally polarized proton beams at 100 x 100 GeV. At 250 x 250 GeV an intermediate boson W production with the longitudinally polarized beams was studied for the first time.

  19. Spin models of the proton

    SciTech Connect

    Ramsey, G.P.

    1988-10-20

    We have constructed a model of the proton spin based on a broken SU(6) parameterization for the spin-weighted valence quark distributions in a longitudinally polarized proton. The polarized sea and gluon distributions are assumed to have simple relations to the corresponding unpolarized structure functions. The sum rules, which involve the non-singlet components of the structure function xg/sub 1/, imply that the valence quarks carry about 78% of the proton spin, while the spin carried by sea quarks is negative. Recent EMC data suggest a model in which the sea quarks carry a large negative polarization, whereas certain theoretical arguments favor a model with a smaller negatively polarized sea. These models are discussed with reference to the sum rules. Experiments are suggested which will discriminate between these models. 24 refs., 4 figs.

  20. Nanoantioxidant-driven plasmon enhanced proton-coupled electron transfer

    NASA Astrophysics Data System (ADS)

    Sotiriou, Georgios A.; Blattmann, Christoph O.; Deligiannakis, Yiannis

    2015-12-01

    Proton-coupled electron transfer (PCET) reactions involve the transfer of a proton and an electron and play an important role in a number of chemical and biological processes. Here, we describe a novel phenomenon, plasmon-enhanced PCET, which is manifested using SiO2-coated Ag nanoparticles functionalized with gallic acid (GA), a natural antioxidant molecule that can perform PCET. These GA-functionalized nanoparticles show enhanced plasmonic response at near-IR wavelengths, due to particle agglomeration caused by the GA molecules. Near-IR laser irradiation induces strong local hot-spots on the SiO2-coated Ag nanoparticles, as evidenced by surface enhanced Raman scattering (SERS). This leads to plasmon energy transfer to the grafted GA molecules that lowers the GA-OH bond dissociation enthalpy by at least 2 kcal mol-1 and therefore facilitates PCET. The nanoparticle-driven plasmon-enhancement of PCET brings together the so far unrelated research domains of nanoplasmonics and electron/proton translocation with significant impact on applications based on interfacial electron/proton transfer.Proton-coupled electron transfer (PCET) reactions involve the transfer of a proton and an electron and play an important role in a number of chemical and biological processes. Here, we describe a novel phenomenon, plasmon-enhanced PCET, which is manifested using SiO2-coated Ag nanoparticles functionalized with gallic acid (GA), a natural antioxidant molecule that can perform PCET. These GA-functionalized nanoparticles show enhanced plasmonic response at near-IR wavelengths, due to particle agglomeration caused by the GA molecules. Near-IR laser irradiation induces strong local hot-spots on the SiO2-coated Ag nanoparticles, as evidenced by surface enhanced Raman scattering (SERS). This leads to plasmon energy transfer to the grafted GA molecules that lowers the GA-OH bond dissociation enthalpy by at least 2 kcal mol-1 and therefore facilitates PCET. The nanoparticle-driven plasmon

  1. Enhancing proton conduction via doping of supramolecular liquid crystals (4-alkoxybenzoic acids) with imidazole

    NASA Astrophysics Data System (ADS)

    Liang, Ting; Wu, Yong; Tan, Shuai; Yang, Xiaohui; Wei, Bingzhuo

    2015-09-01

    Enhancing proton conduction via doping was first achieved in hydrogen-bonded liquid crystals consisting of benzoic acids. Supramolecular liquid crystals formed by pure 4-alkoxybenzoic acids (nAOBA, n = 8, 10, 12) exhibited the maximum proton conductivity of 5.0 × 10-8 S cm-1. Doping of nAOBA with 25 mol% imidazole (Im0.25) had little impact on mesomorphism but increased proton conductivities by at least 3 orders of magnitude. The liquid crystals formed by nAOBA-Im0.25 exhibited the maximum proton conductivity of 1.9 × 10-4 S cm-1. It was proposed that structure diffusion of imidazole bridged interdimer proton transfer to form continuous conducting pathways in mesomorphic nAOBA-Im0.25.

  2. Nonadiabatic rate constants for proton transfer and proton-coupled electron transfer reactions in solution: Effects of quadratic term in the vibronic coupling expansion

    SciTech Connect

    Soudackov, Alexander; Hammes-Schiffer, Sharon

    2015-11-17

    Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency regimes for the proton donor-acceptor vibrational mode. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term does not significantly impact the rate constants derived using the cumulant expansion approach in any of the regimes studied. The effects of the quadratic term may become significant when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant, however, particularly at high temperatures and for proton transfer interfaces with extremely soft proton donor-acceptor modes that are associated with extraordinarily weak hydrogen bonds. Even with the thermal averaging procedure, the effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances, and the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton transfer and proton-coupled electron transfer in chemical and biological processes. We are grateful for support from National Institutes of Health Grant GM056207 (applications to enzymes) and the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy

  3. Proton aurora and substorm intensifications

    NASA Technical Reports Server (NTRS)

    Samson, J. C.; Xu, B.; Lyons, L. R.; Newell, P. T.; Creutzberg, F.

    1993-01-01

    Ground based measurements from the CANOPUS array of meridian scanning photometers and precipitating ion and electron data from the DMSP F9 satellite show that the electron arc which brightens to initiate substorm intensifications is formed within a region of intense proton precipitation that is well equatorward (approximately four to six degrees) of the nightside open-closed field line boundary. The precipitating protons are from a population that is energized via earthward convection from the magnetotail into the dipolar region of the magnetosphere and may play an important role in the formation of the electron arcs leading to substorm intensifications on dipole-like field lines.

  4. Active interrogation using energetic protons

    SciTech Connect

    Morris, Christopher L; Chung, Kiwhan; Greene, Steven J; Hogan, Gary E; Makela, Mark; Mariam, Fesseha; Milner, Edward C; Murray, Matthew; Saunders, Alexander; Spaulding, Randy; Wang, Zhehui; Waters, Laurie; Wysocki, Frederick

    2010-01-01

    Energetic proton beams provide an attractive alternative when compared to electromagnetic and neutron beams for active interrogation of nuclear threats because they have large fission cross sections, long mean free paths and high penetration, and they can be manipulated with magnetic optics. We have measured time-dependent cross sections and neutron yields for delayed neutrons and gamma rays using 800 MeV and 4 GeV proton beams with a set of bare and shielded targets. The results show significant signals from both unshielded and shielded nuclear materials. Measurements of neutron energies yield suggest a signature unique to fissile material. Results are presented in this paper.

  5. Vision 20/20: Proton therapy

    SciTech Connect

    Smith, Alfred R.

    2009-02-15

    The first patients were treated with proton beams in 1955 at the Lawrence Berkeley Laboratory in California. In 1970, proton beams began to be used in research facilities to treat cancer patients using fractionated treatment regimens. It was not until 1990 that proton treatments were carried out in hospital-based facilities using technology and techniques that were comparable to those for modern photon therapy. Clinical data strongly support the conclusion that proton therapy is superior to conventional radiation therapy in a number of disease sites. Treatment planning studies have shown that proton dose distributions are superior to those for photons in a wide range of disease sites indicating that additional clinical gains can be achieved if these treatment plans can be reliably delivered to patients. Optimum proton dose distributions can be achieved with intensity modulated protons (IMPT), but very few patients have received this advanced form of treatment. It is anticipated widespread implementation of IMPT would provide additional improvements in clinical outcomes. Advances in the last decade have led to an increased interest in proton therapy. Currently, proton therapy is undergoing transitions that will move it into the mainstream of cancer treatment. For example, proton therapy is now reimbursed, there has been rapid development in proton therapy technology, and many new options are available for equipment, facility configuration, and financing. During the next decade, new developments will increase the efficiency and accuracy of proton therapy and enhance our ability to verify treatment planning calculations and perform quality assurance for proton therapy delivery. With the implementation of new multi-institution clinical studies and the routine availability of IMPT, it may be possible, within the next decade, to quantify the clinical gains obtained from optimized proton therapy. During this same period several new proton therapy facilities will be built

  6. Towards Precision Proton Tomography

    NASA Astrophysics Data System (ADS)

    Elouadrhiri, Latifa

    2007-04-01

    Generalized Patron Distributions (GPDs) contain a wealth of information about hadron structure. Mapping the GPDs will allow one, for the first time, to construct ``tomographic'' images of the nucleon's charge and quark helicity distributions in transverse impact parameter space. GPDs can be accessed through lepton scattering processes such as Deeeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP). Different facilities world --wide including HERMES at HERA, CLAS and Hall-A at JLab and COMPASS at CERN have measurements of hard exclusive processes as one of their main focuses of research. In this talk we present an overview of the latest developments in the study of GPDs and newly released results will be also presented. The talk will conclude with prospects of the GPD program at existing and planned machines.

  7. Measurement of pion, kaon and proton production in proton-proton collisions at TeV

    NASA Astrophysics Data System (ADS)

    Adam, J.; Adamová, D.; Aggarwal, M. M.; Rinella, G. Aglieri; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmed, I.; Ahn, S. U.; Aimo, I.; Aiola, S.; Ajaz, M.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Molina, R. Alfaro; Alici, A.; Alkin, A.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Prado, C. Alves Garcia; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Ball, M.; Pedrosa, F. Baltasar Dos Santos; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Camejo, A. Batista; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Martinez, H. Bello; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biswas, S.; Bjelogrlic, S.; Blanco, F.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botje, M.; Botta, E.; Böttger, S.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Diaz, L. Calero; Caliva, A.; Villar, E. Calvo; Camerini, P.; Carena, F.; Carena, W.; Castellanos, J. Castillo; Castro, A. J.; Casula, E. A. R.; Cavicchioli, C.; Sanchez, C. Ceballos; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Barroso, V. Chibante; Chinellato, D. D.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Balbastre, G. Conesa; Valle, Z. Conesa del; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Morales, Y. Corrales; Maldonado, I. Cortés; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Albino, R. Cruz; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; De, S.; Caro, A. De; Cataldo, G. de; Cuveland, J. de; Falco, A. De; Gruttola, D. De; Marco, N. De; Pasquale, S. De; Deisting, A.; Deloff, A.; Dénes, E.; D'Erasmo, G.; Bari, D. Di; Mauro, A. Di; Nezza, P. Di; Corchero, M. A. Diaz; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Gimenez, D. Domenicis; Dönigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Engel, H.; Erazmus, B.; Erhardt, F.; Eschweiler, D.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Felea, D.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Téllez, A. Fernández; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Furs, A.; Girard, M. Fusco; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Dziadus, E. Gladysz; Glässel, P.; Ramirez, A. Gomez; Zamora, P. González; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Graczykowski, L. K.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gulkanyan, H.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hanratty, L. D.; Hansen, A.; Harris, J. W.; Hartmann, H.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Heide, M.; Helstrup, H.; Herghelegiu, A.; Corral, G. Herrera; Hess, B. A.; Hetland, K. F.; Hilden, T. E.; Hillemanns, H.; Hippolyte, B.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Ilkiv, I.; Inaba, M.; Ionita, C.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacobs, P. M.; Jahnke, C.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Bustamante, R. T. Jimenez; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Uysal, A. Karasu; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Khan, K. H.; Khan, M. M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, B.; Kim, D. W.; Kim, D. J.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobayashi, T.; Kobdaj, C.; Kofarago, M.; Köhler, M. K.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Kox, S.; Meethaleveedu, G. Koyithatta; Kral, J.; Králik, I.; Kravčáková, A.; Krelina, M.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kucheriaev, Y.; Kugathasan, T.; Kuhn, C.; Kuijer, P. G.; Kulakov, I.; Kumar, J.; Kumar, L.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kushpil, S.; Kweon, M. J.; Kwon, Y.; Pointe, S. L. La; Rocca, P. La; Fernandes, C. Lagana; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Legrand, I.; Lehnert, J.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; Monzón, I. León; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loggins, V. R.; Loginov, V.; Loizides, C.; Lopez, X.; Torres, E. López; Lowe, A.; Lu, X.-G.; Luettig, P.; Lunardon, M.; Luparello, G.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Cervantes, I. Maldonado; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manceau, L.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Blanco, J. Martin; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Pedreira, M. Martinez; Martynov, Y.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Masui, H.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; Mcdonald, D.; Meddi, F.; Menchaca-Rocha, A.; Meninno, E.; Pérez, J. Mercado; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Zetina, L. Montaño; Montes, E.; Morando, M.; Godoy, D. A. Moreira De; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Müller, H.; Mulligan, J. D.; Munhoz, M. G.; Murray, S.; Musa, L.; Musinsky, J.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Nattrass, C.; Nayak, K.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Silva, A. C. Oliveira Da; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Velasquez, A. Ortiz; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pajares, C.; Pal, S. K.; Pan, J.; Pandey, A. K.; Pant, D.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Paul, B.; Pawlak, T.; Peitzmann, T.; Costa, H. Pereira Da; Filho, E. Pereira De Oliveira; Peresunko, D.; Lara, C. E. Pérez; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Razazi, V.; Read, K. F.; Real, J. S.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reicher, M.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Rettig, F.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rivetti, A.; Rocco, E.; Cahuantzi, M. Rodríguez; Manso, A. Rodriguez; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Montero, A. J. Rubio; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salgado, C. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Castro, X. Sanchez; Šándor, L.; Sandoval, A.; Sano, M.; Santagati, G.; Sarkar, D.; Scapparone, E.; Scarlassara, F.; Scharenberg, R. P.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Seeder, K. S.; Seger, J. E.; Sekiguchi, Y.; Selyuzhenkov, I.; Senosi, K.; Seo, J.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Soltz, R.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; Spacek, M.; Spiriti, E.; Sputowska, I.; Stassinaki, M. Spyropoulou; Srivastava, B. K.; Stachel, J.; Stan, I.; Stefanek, G.; Steinpreis, M.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Sultanov, R.; Šumbera, M.; Symons, T. J. M.; Szabo, A.; Toledo, A. Szanto de; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Takahashi, J.; Tanaka, N.; Tangaro, M. A.; Takaki, J. D. Tapia; Peloni, A. Tarantola; Tariq, M.; Tarzila, M. G.; Tauro, A.; Muñoz, G. Tejeda; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Palomo, L. Valencia; Vallero, S.; Maarel, J. Van Der; Hoorne, J. W. Van; Leeuwen, M. van; Vanat, T.; Vyvre, P. Vande; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Limón, S. Vergara; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Baillie, O. Villalobos; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; Haller, B. von; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Vyushin, A.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Wang, Y.; Watanabe, D.; Weber, M.; Weber, S. G.; Wessels, J. P.; Westerhoff, U.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yamaguchi, Y.; Yang, H.; Yang, P.; Yano, S.; Yasnopolskiy, S.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zhu, X.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.

    2015-05-01

    The measurement of primary , , and production at mid-rapidity ( 0.5) in proton-proton collisions at 7 TeV performed with a large ion collider experiment at the large hadron collider (LHC) is reported. Particle identification is performed using the specific ionisation energy-loss and time-of-flight information, the ring-imaging Cherenkov technique and the kink-topology identification of weak decays of charged kaons. Transverse momentum spectra are measured from 0.1 up to 3 GeV/ for pions, from 0.2 up to 6 GeV/ for kaons and from 0.3 up to 6 GeV/ for protons. The measured spectra and particle ratios are compared with quantum chromodynamics-inspired models, tuned to reproduce also the earlier measurements performed at the LHC. Furthermore, the integrated particle yields and ratios as well as the average transverse momenta are compared with results at lower collision energies.

  8. Fast proton conducting glasses: Creation by proton implantation and a requirement for fast proton conduction

    SciTech Connect

    Hosono, H.; Kawamura, K.; Kawazoe, H.; Matsunami, N.; Abe, Y.

    1997-02-01

    Fast proton conducting glasses have been obtained in Mg(PO{sub 3}){sub 2} glasses by implantation of protons at 120 keV to a fluence of 1{times}10{sup 18} cm{sup {minus}2}. The dc conductivity and the activation energy of the conduction in the implanted glasses are 5{times}10{sup {minus}4} scm{sup {minus}1} at room temperature and 0.18 eV, respectively. No fast proton conduction was observed for H{sup +}-implanted SiO{sub 2} and Ca(PO{sub 3}){sub 2} glasses. Infrared absorption spectra revealed that implanted protons are present in the form of X{endash}OH (X=Si or P) in SiO{sub 2} and Ca(PO{sub 3}){sub 2} glasses implanted with H{sup +} ions to 1{times}10{sup 18} cm{sup {minus}2}, but exist as POH groups and molecular water H{sub 2}O in Mg(PO{sub 3}){sub 2} glasses. A quantitative discussion on the proton conductivity led to the conclusion that the coexistence of acidic groups such as POH and molecular water H{sub 2}O is a structural requirement for the emergence of fast proton conduction in oxide glasses. The formation of H{sub 2}O in Mg(PO{sub 3}){sub 2} was understood by considering its thermodynamic stability over SiO{sub 2} and Ca(PO{sub 3}){sub 2} glasses. {copyright} {ital 1997 American Institute of Physics.}

  9. Random and Block Sulfonated Polyaramides as Advanced Proton Exchange Membranes

    SciTech Connect

    Kinsinger, Corey L.; Liu, Yuan; Liu, Feilong; Yang, Yuan; Seifert, Soenke; Knauss, Daniel M.; Herring, Andrew M; Maupin, C. Mark

    2015-11-05

    Presented here is the experimental and computational characterization of two novel copolyaramide proton exchange membranes (PEMs) with higher conductivity than Nafion at relatively high temperatures, good mechanical properties, high thermal stability, and the capability to operate in low humidity conditions. The random and block copolyaramide PEMs are found to possess different ion exchange capacities (IEC) in addition to subtle structural and morphological differences, which impact the stability and conductivity of the membranes. SAXS patterns indicate the ionomer peak for the dry block copolymer resides at q = 0.1 Å–1, which increases in amplitude when initially hydrated to 25% relative humidity, but then decrease in amplitude with additional hydration. This pattern is hypothesized to signal the transport of water into the polymer matrix resulting in a reduced degree of phase separation. Coupled to these morphological changes, the enhanced proton transport characteristics and structural/mechanical stability for the block copolymer are hypothesized to be primarily due to the ordered structure of ionic clusters that create connected proton transport pathways while reducing swelling upon hydration. Interestingly, the random copolymer did not possess an ionomer peak at any of the hydration levels investigated, indicating a lack of any significant ionomer structure. The random copolymer also demonstrated higher proton conductivity than the block copolymer, which is opposite to the trend normally seen in polymer membranes. However, it has reduced structural/mechanical stability as compared to the block copolymer. This reduction in stability is due to the random morphology formed by entanglements of polymer chains and the adverse swelling characteristics upon hydration. Therefore, the block copolymer with its enhanced proton conductivity characteristics, as compared to Nafion, and favorable structural/mechanical stability, as compared to the random copolymer

  10. The Proton Form Factor Ratio Measurements at Jefferson Lab

    SciTech Connect

    Punjabi, Vina A.; Perdrisat, Charles F.

    2014-03-01

    The ratio of the proton form factors, G{sub Ep}/G{sub Mp}, has been measured from Q{sup 2} of 0.5 GeV{sup 2} to 8.5 GeV{sup 2}, at the Jefferson Laboratory, using the polarization transfer method. This ratio is extracted directly from the measured ratio of the transverse and longitudinal polarization components of the recoiling proton in elastic electron-proton scattering. The discovery that the proton form factor ratio measured in these experiments decreases approximately linearly with four-momentum transfer, Q{sup 2}, for values above ~1 GeV{sup 2}, is one of the most significant results to come out of JLab. These results have had a large impact on progress in hadronic physics; and have required a significant rethinking of nucleon structure. The increasingly common use of the double-polarization technique to measure the nucleon form factors, in the last 15 years, has resulted in a dramatic improvement of the quality of all four nucleon electromagnetic form factors, G{sub Ep}, G{sub Mp}, G{sub En} and G{sub Mn}. There is an approved experiment at JLab, GEP(V), to continue the ratio measurements to 12 GeV{sup 2}. A dedicated experimental setup, the Super Bigbite Spectrometer (SBS), will be built for this purpose. It will be equipped with a focal plane polarimeter to measure the polarization of the recoil protons. The scattered electrons will be detected in an electromagnetic calorimeter. In this presentation, I will review the status of the proton elastic electromagnetic form factors and discuss a number of theoretical approaches to describe nucleon form factors.

  11. Electron and Proton Auroral Dynamics

    NASA Technical Reports Server (NTRS)

    Mende, S. B.; Frey, H. U.; Gerard, J. C.; Hubert, B.; Fuselier, S.; Spann, J. F., Jr.; Gladstone, R.; Burch, J. L.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Data from the Wide-band Imaging Camera (WIC) sensitive to far ultraviolet auroras and from the Spectrographic Imager (SI) channel SI12, sensitive to proton precipitation induced Lyman alpha were analyzed during a high altitude orbit segment of the IMAGE spacecraft. This segment began during the expansive phase of a substorm. The aurora changed into a double oval configuration, consisting of a set of discrete pole-ward forms and a separate diffuse auroral oval equatorwards, Although IMF Bz was strongly southward considerable activity could be seen poleward of the discrete auroras in the region that was considered to be the polar cap. The SI12 Doppler shifted Lyman alpha signature of precipitating protons show that the proton aurora is on the equatorward side of the diffuse aurora. In the following several hours the IMF Bz field changed signed. Although the general character of the proton and electron aurora did not change, the dayside aurora moved equatorward when the Bz was negative and more bright aurora was seen in the central polar cap during periods of positive Bz.

  12. Invariant Spin in the Proton

    SciTech Connect

    Thomas, Anthony

    2008-11-01

    We discuss recent theoretical progress in understanding the distribution of spin and orbital angular momentum in the proton. Particular attention is devoted to the effect of QCD evolution and to the distinction between "chiral" and "invariant" spin. This is particularly significant with respect to the possible presence of polarized strange quarks.

  13. Invariant Spin in the Proton

    SciTech Connect

    Thomas, Anthony W.

    2008-10-13

    We discuss recent theoretical progress in understanding the distribution of spin and orbital angular momentum in the proton. Particular attention is devoted to the effect of QCD evolution and to the distinction between 'chiral' and 'invariant' spin. This is particularly significant with respect to the possible presence of polarized strange quarks.

  14. Gluon polarization in the proton

    SciTech Connect

    Bass, Steven D.; Casey, Andrew; Thomas, Anthony W.

    2011-03-15

    We combine heavy-quark renormalization group arguments with our understanding of the nucleon's wave function to deduce a bound on the gluon polarization {Delta}g in the proton. The bound is consistent with the values extracted from spin experiments at COMPASS and RHIC.

  15. Alpha proton x ray spectrometer

    NASA Technical Reports Server (NTRS)

    Rieder, Rudi; Waeke, H.; Economou, T.

    1994-01-01

    Mars Pathfinder will carry an alpha-proton x ray spectrometer (APX) for the determination of the elemental chemical composition of Martian rocks and soils. The instrument will measure the concentration of all major and some minor elements, including C, N, and O at levels above typically 1 percent.

  16. Proton pump inhibitor-induced hypomagnesemic hypoparathyroidism.

    PubMed

    Swaminathan, Krishnan

    2015-01-01

    Proton pump inhibitors are the one of the most widely used drugs in the world. Hypomagnesemic hypoparathyroidism has been reported with different proton pump inhibitors with prolonged oral use. We report the first reported case of possible such effect with intravenous preparation of proton pump inhibitor. This case report raises awareness among physicians worldwide of this often unknown association, as life-threatening cardiac and neuromuscular complications can arise with unrecognized hypocalcemia and hypomagnesemia with proton pump inhibitors.

  17. Low-Energy Proton Testing Methodology

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Marshall, Paul W.; Heidel, David F.; Schwank, James R.; Shaneyfelt, Marty R.; Xapsos, M.A.; Ladbury, Raymond L.; LaBel, Kenneth A.; Berg, Melanie; Kim, Hak S.; Phan, Anthony; Friendlich, M.R.; Rodbell, Kenneth P.; Hakey, Mark C.; Dodd, Paul E.; Reed, Robert A.; Weller, Robert A.; Mendenhall, Marcus H.; Sierawski, B.D.

    2009-01-01

    Use of low-energy protons and high-energy light ions is becoming necessary to investigate current-generation SEU thresholds. Systematic errors can dominate measurements made with low-energy protons. Range and energy straggling contribute to systematic error. Low-energy proton testing is not a step-and-repeat process. Low-energy protons and high-energy light ions can be used to measure SEU cross section of single sensitive features; important for simulation.

  18. Proton-Nucleus Scattering Approximations and Implications for LHC Crystal Collimation

    SciTech Connect

    Noble, Robert; /SLAC

    2010-06-07

    In particle accelerators, scattered protons with energies close to the incident particles may travel considerable distances with the beam before impacting on accelerator components downstream. To analyze such problems, angular deflection and energy loss of scattered particles are the main quantities to be simulated since these lead to changes in the beam's phase space distribution and particle loss. Simple approximations for nuclear scattering processes causing limited energy loss to high-energy protons traversing matter are developed which are suitable for rapid estimates and reduced-description Monte Carlo simulations. The implications for proton loss in the Large Hadron Collider due to nuclear scattering on collimation crystals are discussed.

  19. The size of the proton.

    PubMed

    Pohl, Randolf; Antognini, Aldo; Nez, François; Amaro, Fernando D; Biraben, François; Cardoso, João M R; Covita, Daniel S; Dax, Andreas; Dhawan, Satish; Fernandes, Luis M P; Giesen, Adolf; Graf, Thomas; Hänsch, Theodor W; Indelicato, Paul; Julien, Lucile; Kao, Cheng-Yang; Knowles, Paul; Le Bigot, Eric-Olivier; Liu, Yi-Wei; Lopes, José A M; Ludhova, Livia; Monteiro, Cristina M B; Mulhauser, Françoise; Nebel, Tobias; Rabinowitz, Paul; Dos Santos, Joaquim M F; Schaller, Lukas A; Schuhmann, Karsten; Schwob, Catherine; Taqqu, David; Veloso, João F C A; Kottmann, Franz

    2010-07-01

    The proton is the primary building block of the visible Universe, but many of its properties-such as its charge radius and its anomalous magnetic moment-are not well understood. The root-mean-square charge radius, r(p), has been determined with an accuracy of 2 per cent (at best) by electron-proton scattering experiments. The present most accurate value of r(p) (with an uncertainty of 1 per cent) is given by the CODATA compilation of physical constants. This value is based mainly on precision spectroscopy of atomic hydrogen and calculations of bound-state quantum electrodynamics (QED; refs 8, 9). The accuracy of r(p) as deduced from electron-proton scattering limits the testing of bound-state QED in atomic hydrogen as well as the determination of the Rydberg constant (currently the most accurately measured fundamental physical constant). An attractive means to improve the accuracy in the measurement of r(p) is provided by muonic hydrogen (a proton orbited by a negative muon); its much smaller Bohr radius compared to ordinary atomic hydrogen causes enhancement of effects related to the finite size of the proton. In particular, the Lamb shift (the energy difference between the 2S(1/2) and 2P(1/2) states) is affected by as much as 2 per cent. Here we use pulsed laser spectroscopy to measure a muonic Lamb shift of 49,881.88(76) GHz. On the basis of present calculations of fine and hyperfine splittings and QED terms, we find r(p) = 0.84184(67) fm, which differs by 5.0 standard deviations from the CODATA value of 0.8768(69) fm. Our result implies that either the Rydberg constant has to be shifted by -110 kHz/c (4.9 standard deviations), or the calculations of the QED effects in atomic hydrogen or muonic hydrogen atoms are insufficient. PMID:20613837

  20. Proton structure functions at HERA

    NASA Astrophysics Data System (ADS)

    Stella, Bruno

    2001-10-01

    The electron-proton collider HERA, like an electron-mycroscope, explores the structure of the proton down to 10-16 cm and up to the situation of very high parton densities. The proton energy was upgraded from 820 to 920 GeV in the Fall of '98 and the luminosity has also substantially improved, with another factor of 3 upgrade expected to follow this year. Inclusive proton structure functions have been studied with incident e+ and e- of 27 GeV in the neutral (NC) and charged (CC) current interactions as functions of the squared four-momentum transfer, Q2, and of the fractional proton momentum carried by partons, x. The structure function F2, as well as the γ-Z0 interference term xF3, have been measured in a range of Q2 and 1/x that extends by orders of magnitude that reached by fixed target experiments. The DGLAP evolution equations [1] allow for a perturbative NLO QCD fit of the measured non-perturbative structure functions in the available kinematic range: αS and the gluon density at low x are fitted at the same time with good precision. The longitudinal structure function, FL, can be determined within the DGLAP formalism. With CC, the electroweak unification has been tested; at high x, a first flavor decomposition of the light quarks is achieved. The contribution to F2 of the charm quark has been measured and results to be relevant. Bounds on the radius of quarks and on compositeness are derived from the data at the highest Q2, 100

  1. Proton structure functions at HERA

    NASA Astrophysics Data System (ADS)

    H1; ZEUS Collaborations,

    2001-10-01

    The electron-proton collider HERA, like an electron-mycroscope, explores the structure of the proton down to 10-16 cm and up to the situation of very high parton densities. The proton energy was upgraded from 820 to 920 GeV in the Fall of '98 and the luminosity has also substantially improved, with another factor of 3 upgrade expected to follow this year. Inclusive proton structure functions have been studied with incident e+ and e- of 27 GeV in the neutral (NC) and charged (CC) current interactions as functions of the squared four-momentum transfer, Q2, and of the fractional proton momentum carried by partons, x. The structure function F2, as well as the γ-Z0 interference term xF3, have been measured in a range of Q2 and 1/x that extends by orders of magnitude that reached by fixed target experiments. The DGLAP evolution equations [1] allow for a perturbative NLO QCD fit of the measured non-perturbative structure functions in the available kinematic range: αS and the gluon density at low x are fitted at the same time with good precision. The longitudinal structure function, FL, can be determined within the DGLAP formalism. With CC, the electroweak unification has been tested; at high x, a first flavor decomposition of the light quarks is achieved. The contribution to F2 of the charm quark has been measured and results to be relevant. Bounds on the radius of quarks and on compositeness are derived from the data at the highest Q2, 100

  2. Dosimetric accuracy of proton therapy for chordoma patients with titanium implants

    PubMed Central

    Verburg, Joost M.; Seco, Joao

    2013-01-01

    Purpose: To investigate dosimetric errors in proton therapy treatment planning due to titanium implants, and to determine how these affect postoperative passively scattered proton therapy for chordoma patients with orthopedic hardware. Methods: The presence of titanium hardware near the tumor may affect the dosimetric accuracy of proton therapy. Artifacts in the computed tomography (CT) scan can cause errors in the proton stopping powers used for dose calculation, which are derived from CT numbers. Also, clinical dose calculation algorithms may not accurately simulate proton beam transport through the implants, which have very different properties as compared to human tissue. The authors first evaluated the impact of these two main issues. Dose errors introduced by metal artifacts were studied using phantoms with and without titanium inserts, and patient scans on which a metal artifact reduction method was applied. Pencil-beam dose calculations were compared to models of nuclear interactions in titanium and Monte Carlo simulations. Then, to assess the overall impact on treatment plans for chordoma, the authors compared the original clinical treatment plans to recalculated dose distributions employing both metal artifact reduction and Monte Carlo methods. Results: Dose recalculations of clinical proton fields showed that metal artifacts cause range errors up to 6 mm distal to regions affected by CT artifacts. Monte Carlo simulations revealed dose differences >10% in the high-dose area, and range differences up to 10 mm. Since these errors are mostly local in nature, the large number of fields limits the impact on target coverage in the chordoma treatment plans to a small decrease of dose homogeneity. Conclusions: In the presence of titanium implants, CT metal artifacts and the approximations of pencil-beam dose calculations cause considerable errors in proton dose calculation. The spatial distribution of the errors however limits the overall impact on passively

  3. Nonplanarity and the protonation behavior of porphyrins

    SciTech Connect

    SOMMA,MARIA S.; MEDFORTH,CRAIG J.; TH,KEVIN M.; SHELNUTT,JOHN A.

    2000-03-21

    {sup 1}H NMR studies of the protonation of highly nonplanar porphyrins with strong acids reveal the presence of the previously elusive monocation, and show that its stability can be related to the amount of saddle distortion induced by protonation; the amount of saddle distortion for a porphyrin dication is also found to correlate well with the rate of intermolecular proton transfer.

  4. Threshold pion production from proton-proton collisions

    SciTech Connect

    Lee, T.S.H.

    1995-08-01

    We showed that the threshold production of {pi}{sup 0}pp, {pi}{sup +}np, and {pi}{sup +}d from proton-proton collisions can be consistently described by a model consisting of pion s-wave rescattering and N{bar N} pair-terms of heavy-meson exchanges. The large difference between {sigma}{sup tot}(pp {yields} {pi}{sup +}d) and {sigma}{sup tot}(pp {yields} {pi}{sup +}np) is understood from the orthogonality of the deuteron and the np scattering wave functions. In a calculation using the Paris potential, we find that the data can be reproduced best by using a soft {pi}NN form factor with {Delta} = 650 MeV for a monopole form. This is consistent with our earlier studies of pion production in the A-excitation region. A paper describing this result was submitted for publication.

  5. Calculation of Top Squark Production in Proton-Proton Collisions

    SciTech Connect

    Linville, Andrea J.; /Washington U., St. Louis /SLAC

    2010-08-25

    Though the Standard Model of particle physics is an elegant theory which has been studied extensively for decades, it leaves many fundamental questions unanswered and is thus widely believed to be incomplete. Possible extensions to the Standard Model (SM) have been postulated and are in the process of being investigated experimentally. The most promising extension is the Minimal Supersymmetric Model (MSSM) which relates every SM particle to a superpartner that differs by 1/2 unit of spin. The lightest supersymmetric quark, or squark, is expected to be the stop, and the search for this particle is an important experimental task. In this analysis, we use parton-model methods to predict the stop production cross section in proton-proton collisions at LHC energies.

  6. Proton beam therapy for locally advanced lung cancer: A review

    PubMed Central

    Schild, Steven E; Rule, William G; Ashman, Jonathan B; Vora, Sujay A; Keole, Sameer; Anand, Aman; Liu, Wei; Bues, Martin

    2014-01-01

    Protons interact with human tissue differently than do photons and these differences can be exploited in an attempt to improve the care of lung cancer patients. This review examines proton beam therapy (PBT) as a component of a combined modality program for locally advanced lung cancers. It was specifically written for the non-radiation oncologist who desires greater understanding of this newer treatment modality. This review describes and compares photon (X-ray) radiotherapy (XRT) to PBT. The physical differences of these beams are described and the clinical literature is reviewed. Protons can be used to create treatment plans delivering significantly lower doses of radiation to the adjacent organs at risk (lungs, esophagus, and bone marrow) than photons. Clinically, PBT combined with chemotherapy has resulted in low rates of toxicity compared to XRT. Early results suggest a possible improvement in survival. The clinical results of proton therapy in lung cancer patients reveal relatively low rates of toxicity and possible survival benefits. One randomized study is being performed and another is planned to clarify the clinical differences in patient outcome for PBT compared to XRT. Along with the development of better systemic therapy, newer forms of radiotherapy such as PBT should positively impact the care of lung cancer patients. This review provides the reader with the current status of this new technology in treating locally advanced lung cancer. PMID:25302161

  7. ETFE polymer bombarded with 1 MeV proton

    NASA Astrophysics Data System (ADS)

    Parada, M. A.; de Almeida, A.; Muntele, I.; Muntele, C.; Delalez, N.; Ila, D.

    2005-12-01

    The ethylenetetrafluoroethylene (ETFE) is a polymer formed by alternating ethylene and tetrafluoroethylene segments. It has high impact resistance and useful mechanical properties. ETFE can be used as components of pumps, valves, tie wraps, and electrical components. It can also be applied in the field of medical physics as intra venous catheters and as radiation dosimeter. When a material is exposed to the ionizing radiation, it suffers damage that depends on the type, energy and intensity of the radiation. In order to determine the radiation damage mechanism, ETFE films were bombarded with 1 MeV protons to the fluence between 1 × 1011 and 1 × 1016 protons/cm2 and the chemical species emitted during the bombardment were measured with residual gas analysis (RGA) and show that HF gas is the entity preferentially emitted. Optical absorption photospectrometry (OAP) and attenuated total reflectometry fourier transform infrared (ATR-FTIR) shows quantitative chemical evidence of the damage. Our results show that damage is detectable at low proton fluence, but damage that can compromise the application in dosimetry occurs only for fluence greater than 1014 protons/cm2.

  8. Proton-Proton Weak Capture in Chiral Effective Field Theory

    SciTech Connect

    Marcucci, Laura Elisa; Schiavilla, Rocco; Viviani, MIchele

    2013-05-01

    The astrophysical $S$-factor for proton-proton weak capture is calculated in chiral effective field theory over the center-of-mass relative-energy range 0--100 keV. The chiral two-nucleon potential derived up to next-to-next-to-next-to leading order is augmented by the full electromagnetic interaction including, beyond Coulomb, two-photon and vacuum-polarization corrections. The low-energy constants (LEC's) entering the weak current operators are fixed so as to reproduce the $A=3$ binding energies and magnetic moments, and the Gamow-Teller matrix element in tritium $\\beta$ decay. Contributions from $S$ and $P$ partial waves in the incoming two-proton channel are retained. The $S$-factor at zero energy is found to be $S(0)=(4.030 \\pm 0.006)\\times 10^{-23}$ MeV fm$^2$, with a $P$-wave contribution of $0.020\\times 10^{-23}$ MeV fm$^2$. The theoretical uncertainty is due to the fitting procedure of the LEC's and to the cutoff dependence. It is shown that polynomial fits to parametrize the energy dependence of the $S$-factor are inherently unstable.

  9. Proton-proton weak capture in chiral effective field theory.

    PubMed

    Marcucci, L E; Schiavilla, R; Viviani, M

    2013-05-10

    The astrophysical S factor for proton-proton weak capture is calculated in chiral effective field theory over the center-of-mass relative-energy range 0-100 keV. The chiral two-nucleon potential derived up to next-to-next-to-next-to leading order is augmented by the full electromagnetic interaction including, beyond Coulomb, two-photon and vacuum-polarization corrections. The low-energy constants entering the weak current operators are fixed so as to reproduce the A=3 binding energies and magnetic moments and the Gamow-Teller matrix element in tritium β decay. Contributions from S and P partial waves in the incoming two-proton channel are retained. The S factor at zero energy is found to be S(0)=(4.030±0.006)×10(-23) MeV fm(2), with a P-wave contribution of 0.020×10(-23) MeV fm(2). The theoretical uncertainty is due to the fitting procedure of the low-energy constants and to the cutoff dependence.

  10. Proton-proton weak capture in chiral effective field theory.

    PubMed

    Marcucci, L E; Schiavilla, R; Viviani, M

    2013-05-10

    The astrophysical S factor for proton-proton weak capture is calculated in chiral effective field theory over the center-of-mass relative-energy range 0-100 keV. The chiral two-nucleon potential derived up to next-to-next-to-next-to leading order is augmented by the full electromagnetic interaction including, beyond Coulomb, two-photon and vacuum-polarization corrections. The low-energy constants entering the weak current operators are fixed so as to reproduce the A=3 binding energies and magnetic moments and the Gamow-Teller matrix element in tritium β decay. Contributions from S and P partial waves in the incoming two-proton channel are retained. The S factor at zero energy is found to be S(0)=(4.030±0.006)×10(-23) MeV fm(2), with a P-wave contribution of 0.020×10(-23) MeV fm(2). The theoretical uncertainty is due to the fitting procedure of the low-energy constants and to the cutoff dependence. PMID:23705703

  11. Proton conduction in biopolymer exopolysaccharide succinoglycan

    SciTech Connect

    Kweon, Jin Jung; Lee, Kyu Won; Kim, Hyojung; Lee, Cheol Eui; Jung, Seunho; Kwon, Chanho

    2014-07-07

    Protonic currents play a vital role in electrical signalling in living systems. It has been suggested that succinoglycan plays a specific role in alfalfa root nodule development, presumably acting as the signaling molecules. In this regard, charge transport and proton dynamics in the biopolymer exopolysaccharide succinoglycan have been studied by means of electrical measurements and nuclear magnetic resonance (NMR) spectroscopy. In particular, a dielectric dispersion in the system has revealed that the electrical conduction is protonic rather electronic. Besides, our laboratory- and rotating-frame {sup 1}H NMR measurements have elucidated the nature of the protonic conduction, activation of the protonic motion being associated with a glass transition.

  12. Microscopic dynamics of a base protonation

    NASA Astrophysics Data System (ADS)

    Knudsgaard, Bjørn; Petersen, Christian; Thøgersen, Jan; Keiding, Søren Rud; Jensen, Svend J. Knak

    2008-10-01

    The protonation of the base peroxynitrite in aqueous solution is investigated by way of the Car-Parrinello molecular dynamics technique. It is found that the protonation proceeds through an increase in the vibration amplitude of the hydrogen bond between the base and the hydronium ion. When the amplitude gets sufficiently large a proton may oscillate a few times between the base and the hydronium ion before it remains as part of peroxynitrous acid. The start of the protonation requires a certain orientation of the hydrogen bond. The estimated protonation time agrees well with the one obtained from femtosecond UV experiments.

  13. Kinetic Monte Carlo simulations of proton conductivity

    NASA Astrophysics Data System (ADS)

    Masłowski, T.; Drzewiński, A.; Ulner, J.; Wojtkiewicz, J.; Zdanowska-Frączek, M.; Nordlund, K.; Kuronen, A.

    2014-07-01

    The kinetic Monte Carlo method is used to model the dynamic properties of proton diffusion in anhydrous proton conductors. The results have been discussed with reference to a two-step process called the Grotthuss mechanism. There is a widespread belief that this mechanism is responsible for fast proton mobility. We showed in detail that the relative frequency of reorientation and diffusion processes is crucial for the conductivity. Moreover, the current dependence on proton concentration has been analyzed. In order to test our microscopic model the proton transport in polymer electrolyte membranes based on benzimidazole C7H6N2 molecules is studied.

  14. Excited state of protonated benzene and toluene

    SciTech Connect

    Esteves-López, Natalia; Dedonder-Lardeux, Claude; Jouvet, Christophe

    2015-08-21

    We present photo-fragmentation electronic spectra of the simplest protonated aromatic molecules, protonated benzene and toluene, recorded under medium resolution conditions and compared with the photo-fragmentation spectrum of protonated pyridine. Despite the resolution and cold temperature achieved in the experiment, the electronic spectra of protonated benzene and toluene are structure-less, thus intrinsically broadened. This is in agreement with the large geometrical changes and the fast dynamic toward internal conversion predicted by ab initio calculations for protonated benzene [Rode et al., J. Phys. Chem. A 113, 5865–5873 (2009)].

  15. Compact proton spectrometers for measurements of shock

    SciTech Connect

    Mackinnon, A; Zylstra, A; Frenje, J A; Seguin, F H; Rosenberg, M J; Rinderknecht, H G; Johnson, M G; Casey, D T; Sinenian, N; Manuel, M; Waugh, C J; Sio, H W; Li, C K; Petrasso, R D; Friedrich, S; Knittel, K; Bionta, R; McKernan, M; Callahan, D; Collins, G; Dewald, E; Doeppner, T; Edwards, M J; Glenzer, S H; Hicks, D; Landen, O L; London, R; Meezan, N B

    2012-05-02

    The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign (NIC) diagnostic. The WRF measures the spectrum of protons from D-{sup 3}He reactions in tuning-campaign implosions containing D and {sup 3}He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total {rho}R through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

  16. Proton hydrates as soft ion/ion proton transfer reagents for multiply deprotonated biomolecules

    NASA Astrophysics Data System (ADS)

    Bowers, Jeremiah J.; Hodges, Brittany D. M.; Saad, Ola M.; Leary, Julie A.; McLuckey, Scott A.

    2008-10-01

    Ion/ion proton transfer from protonated strong gaseous bases such as pyridine and 1,8-bis(dimethylamino)naphthalene (i.e., the proton sponge), to multiply charged anions derived from a sulfated pentasaccharide drug, Arixtra(TM), gives rise to extensive fragmentation of the oligosaccharide. This drug serves as a model for sulfated glycosaminoglycans, an important class of polymers in glycobiology. The extent of fragmentation appears to correlate with the proton affinity of the molecule used to transfer the proton, which in turn correlates with the reaction exothermicity. Consistent with tandem mass spectrometry results, anions with sodium counter-ions are more stable with respect to fragmentation under ion/ion proton transfer conditions than ions of the same charge state with protons counter-ions. Proton hydrates were found to give rise to much less anion fragmentation and constitute the softest protonation agents thus far identified for manipulating the charge states of multiply charged biopolymer anions. The reaction exothermicities associated with proton hydrates comprised of five or more water molecules are lower than that for protonated proton sponge, which is among the softest reagents thus far examined for ion/ion proton transfer reactions. The partitioning of ion/ion reaction exothermicity among all of the degrees of freedom of the products may also differ for proton hydrates relative to protonated molecules. However, a difference in energy partitioning need not be invoked to rationalize the results reported here.

  17. Treatment planning, optimization, and beam delivery technqiues for intensity modulated proton therapy

    NASA Astrophysics Data System (ADS)

    Sengbusch, Evan R.

    Physical properties of proton interactions in matter give them a theoretical advantage over photons in radiation therapy for cancer treatment, but they are seldom used relative to photons. The primary barriers to wider acceptance of proton therapy are the technical feasibility, size, and price of proton therapy systems. Several aspects of the proton therapy landscape are investigated, and new techniques for treatment planning, optimization, and beam delivery are presented. The results of these investigations suggest a means by which proton therapy can be delivered more efficiently, effectively, and to a much larger proportion of eligible patients. An analysis of the existing proton therapy market was performed. Personal interviews with over 30 radiation oncology leaders were conducted with regard to the current and future use of proton therapy. In addition, global proton therapy market projections are presented. The results of these investigations serve as motivation and guidance for the subsequent development of treatment system designs and treatment planning, optimization, and beam delivery methods. A major factor impacting the size and cost of proton treatment systems is the maximum energy of the accelerator. Historically, 250 MeV has been the accepted value, but there is minimal quantitative evidence in the literature that supports this standard. A retrospective study of 100 patients is presented that quantifies the maximum proton kinetic energy requirements for cancer treatment, and the impact of those results with regard to treatment system size, cost, and neutron production is discussed. This study is subsequently expanded to include 100 cranial stereotactic radiosurgery (SRS) patients, and the results are discussed in the context of a proposed dedicated proton SRS treatment system. Finally, novel proton therapy optimization and delivery techniques are presented. Algorithms are developed that optimize treatment plans over beam angle, spot size, spot spacing

  18. Proton emission - new results and future prospects

    NASA Astrophysics Data System (ADS)

    Page, R. D.

    2016-09-01

    Proton emission is the radioactive decay mode that is expected to determine the limit of observable proton-rich nuclei for most elements. Considerable progress has been made in the study of proton-emitting nuclei since the first observation of direct proton emission nearly 50 years ago. This has led to improvements in our understanding of this decay process and provided invaluable nuclear structure data far from the valley of beta stability. The rapid fall in half-lives with increasing neutron deficiency when proton emission dominates makes it likely that for some elements, the lightest isotopes whose ground states can be observed in conventional experiments have already been reached. The enhanced stability against proton emission of the recently discovered high-lying isomer in 158Ta raises the possibility that proton emission from multiparticle isomers could be observed in nuclei beyond the expected boundaries of the nuclear landscape.

  19. Dynamic Protonation Equilibrium of Solvated Acetic Acid

    SciTech Connect

    Gu, Wei; Frigato, Tomaso; Straatsma, TP; Helms, Volkhard H.

    2007-04-13

    For the first time, the dynamic protonation equilibrium between an amino acid side chain analogue and bulk water as well as the diffusion properties of the excess proton were successfully reproduced through unbiased computer simulations. During a 50 ns Q-HOP MD simulation, two different regimes of proton transfer were observed. Extended phases of frequent proton swapping between acetic acid and nearby water were separated by phases where the proton freely diffuses in the simulation box until it is captured again by acetic acid. The pKa of acetic acid was calculated around 3.0 based on the relative population of protonated and deprotonated states and the diffusion coefficient of excess proton was computed from the average mean squared displacement in the simulation. Both calculated values agree well with the experimental measurements.

  20. Very energetic protons in Saturn's radiation belt

    NASA Technical Reports Server (NTRS)

    Fillius, W.; Mcilwain, C.

    1980-01-01

    Very energetic protons are trapped in the inner Saturnian radiation belt. The University of California at San Diego instrument on Pioneer 11 has definitely identified protons of energy greater than 80 MeV on channel M3 and has tentatively detected protons of energy greater than 600 MeV on channel C3. The spatial distribution of the protons is distinct from that of the trapped electrons, the main difference being that the protons are strongly absorbed by the innermost moons and that the electrons are not. The source strength for injecting protons by the decay of cosmic ray albedo neutrons generated in the rings of Saturn has been estimated. The required proton lifetime is approximately 20 years.

  1. ACCELERATING POLARIZED PROTONS TO HIGH ENERGY.

    SciTech Connect

    BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; BEEBE-WANG, J.; BLASKIEWICZ, M.; BRAVAR, A.; BRENNAN, J.M.; BRUNO, D.; BUNCE, G.; ET AL.

    2006-10-02

    The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.

  2. Protonated water clusters in TPC's

    NASA Astrophysics Data System (ADS)

    Kaya, Yunus; Kalkan, Yalçın; Veenhof, Rob

    2016-07-01

    Water vapour is added to the ALICE TPC gas to enhance its stability. These polar molecules create large protonated water clusters around a H+ core. In this context, the reactions H3O+(H2 O) n - 1 +H2 O →H3O+(H2O)n (n=1-9) were studied in the gas phase. Structures for these clusters are suggested and the most stable structures for each cluster size are shown. The thermodynamic parameters Δ Hn-1,n0, Δ Gn-1,n0, Δ Sn-1,n0 and equilibrium constants K n - 1 , n for the reaction were calculated to determine the size of the water clusters. The results are close to experimental data found in the literature. Protonated water clusters at stp have a size of 6-9 which corresponds to a mass of 127.1 - 181.2 g / mole.

  3. Proton affinities of hydrated molecules

    NASA Astrophysics Data System (ADS)

    Valadbeigi, Younes

    2016-09-01

    Proton affinities (PA) of non-hydrated, M, and hydrated forms, M(H2O)1,2,3, of 20 organic molecules including alcohols, ethers, aldehydes, ketones and amines were calculated by the B3LYP/6-311++G(d,p) method. For homogeneous families, linear correlations were observed between PAs of the M(H2O)1,2,3 and the PAs of the non-hydrated molecules. Also, the absolute values of the hydration enthalpies of the protonated molecules decreased linearly with the PAs. The correlation functions predicted that for an amine with PA < 1100 kJ/mol the PA(M(H2O)) is larger than the corresponding PA, while for an amine with PA > 1100 kJ/mol the PA(M(H2O)) is smaller than the PA.

  4. External-Beam Accelerated Partial Breast Irradiation Using Multiple Proton Beam Configurations

    SciTech Connect

    Wang Xiaochun; Amos, Richard A.; Zhang Xiaodong; Taddei, Phillip J.; Woodward, Wendy A.; Hoffman, Karen E.; Yu, Tse Kuan; Tereffe, Welela; Oh, Julia; Perkins, George H.; Salehpour, Mohammad; Zhang, Sean X.; Sun, Tzou Liang; Gillin, Michael; Buchholz, Thomas A.; Strom, Eric A.

    2011-08-01

    Purpose: To explore multiple proton beam configurations for optimizing dosimetry and minimizing uncertainties for accelerated partial breast irradiation (APBI) and to compare the dosimetry of proton with that of photon radiotherapy for treatment of the same clinical volumes. Methods and Materials: Proton treatment plans were created for 11 sequential patients treated with three-dimensional radiotherapy (3DCRT) photon APBI using passive scattering proton beams (PSPB) and were compared with clinically treated 3DCRT photon plans. Monte Carlo calculations were used to verify the accuracy of the proton dose calculation from the treatment planning system. The impact of range, motion, and setup uncertainty was evaluated with tangential vs. en face beams. Results: Compared with 3DCRT photons, the absolute reduction of the mean of V100 (the volume receiving 100% of prescription dose), V90, V75, V50, and V20 for normal breast using protons are 3.4%, 8.6%, 11.8%, 17.9%, and 23.6%, respectively. For breast skin, with the similar V90 as 3DCRT photons, the proton plan significantly reduced V75, V50, V30, and V10. The proton plan also significantly reduced the dose to the lung and heart. Dose distributions from Monte Carlo simulations demonstrated minimal deviation from the treatment planning system. The tangential beam configuration showed significantly less dose fluctuation in the chest wall region but was more vulnerable to respiratory motion than that for the en face beams. Worst-case analysis demonstrated the robustness of designed proton beams with range and patient setup uncertainties. Conclusions: APBI using multiple proton beams spares significantly more normal tissue, including nontarget breast and breast skin, than 3DCRT using photons. It is robust, considering the range and patient setup uncertainties.

  5. Proton Resonance Spectroscopy -- Final Report

    SciTech Connect

    Shriner, Jr, J F

    2009-07-27

    This report summarizes work supported by the DOE Grant DE-FG02-96ER40990 during its duration from June 1996 to May 2009. Topics studied include (1) statistical descriptions of nuclear levels and measurements of proton resonances relevant to such descriptions, including measurements toward a complete level scheme for 30P, (2) the development of methods to estimate the missing fraction of levels in a given measurement, and (3) measurements at HRIBF relevant to nuclear astrophysics.

  6. Proton Therapy for Thoracoabdominal Tumors

    NASA Astrophysics Data System (ADS)

    Sakurai, Hideyuki; Okumura, Toshiyuki; Sugahara, Shinji; Nakayama, Hidetsugu; Tokuuye, Koichi

    In advanced-stage disease of certain thoracoabdominal tumors, proton therapy (PT) with concurrent chemotherapy may be an option to reduce side effects. Several technological developments, including a respiratory gating system and implantation of fiducial markers for image guided radiation therapy (IGRT), are necessary for the treatment in thoracoabdominal tumors. In this chapter, the role of PT for tumors of the lung, the esophagus, and liver are discussed.

  7. Proton synchrotron radiation at Fermilab

    SciTech Connect

    Thurman-Keup, Randy; /Fermilab

    2006-05-01

    While protons are not generally associated with synchrotron radiation, they do emit visible light at high enough energies. This paper presents an overview of the use of synchrotron radiation in the Tevatron to measure transverse emittances and to monitor the amount of beam in the abort gap. The latter is necessary to ensure a clean abort and prevent quenches of the superconducting magnets and damage to the silicon detectors of the collider experiments.

  8. Computing proton dose to irregularly moving targets

    NASA Astrophysics Data System (ADS)

    Phillips, Justin; Gueorguiev, Gueorgui; Shackleford, James A.; Grassberger, Clemens; Dowdell, Stephen; Paganetti, Harald; Sharp, Gregory C.

    2014-08-01

    phantom (2 mm, 2%), and 90.8% (3 mm, 3%)for the patient data. Conclusions: We have demonstrated a method for accurately reproducing proton dose to an irregularly moving target from a single CT image. We believe this algorithm could prove a useful tool to study the dosimetric impact of baseline shifts either before or during treatment.

  9. Computing Proton Dose to Irregularly Moving Targets

    PubMed Central

    Phillips, Justin; Gueorguiev, Gueorgui; Shackleford, James A.; Grassberger, Clemens; Dowdell, Stephen; Paganetti, Harald; Sharp, Gregory C.

    2014-01-01

    phantom (2 mm, 2%), and 90.8% (3 mm, 3%)for the patient data. Conclusions We have demonstrated a method for accurately reproducing proton dose to an irregularly moving target from a single CT image. We believe this algorithm could prove a useful tool to study the dosimetric impact of baseline shifts either before or during treatment. PMID:25029239

  10. High-Intensity Proton Accelerator

    SciTech Connect

    Jay L. Hirshfield

    2011-12-27

    Analysis is presented for an eight-cavity proton cyclotron accelerator that could have advantages as compared with other accelerators because of its potentially high acceleration gradient. The high gradient is possible since protons orbit in a sequence of TE111 rotating mode cavities of equally diminishing frequencies with path lengths during acceleration that greatly exceed the cavity lengths. As the cavities operate at sequential harmonics of a basic repetition frequency, phase synchronism can be maintained over a relatively wide injection phase window without undue beam emittance growth. It is shown that use of radial vanes can allow cavity designs with significantly smaller radii, as compared with simple cylindrical cavities. Preliminary beam transport studies show that acceptable extraction and focusing of a proton beam after cyclic motion in this accelerator should be possible. Progress is also reported on design and tests of a four-cavity electron counterpart accelerator for experiments to study effects on beam quality arising from variations injection phase window width. This device is powered by four 500-MW pulsed amplifiers at 1500, 1800, 2100, and 2400 MHz that provide phase synchronous outputs, since they are driven from a with harmonics derived from a phase-locked 300 MHz source.

  11. Proton Beams from Nanotube Accelerator

    NASA Astrophysics Data System (ADS)

    Murakami, Masakatsu; Tanaka, Motohiko

    2013-10-01

    A carbon nanotube (CNT) is known to have extraordinary material and mechanical properties. Here we propose a novel ion acceleration scheme with nanometer-size CNT working at such an extreme circumstance as temperatures higher than billions of degree and durations shorter than tens of femtosecond, dubbed as nanotube accelerator, with which quasimonoenergetic and collimated MeV-order proton beams are generated. In nanotube accelerators, CNTs with fragments of a hydrogen compound embedded inside are irradiated by an ultrashort ultraintense laser. Under such laser and target conditions, low-Z materials such as hydrogen and carbon will be fully ionized. Substantial amount of electrons of the system are then blown off by the brutal laser electric field within only a few laser cycles. This leads to a new type of ion acceleration, in which the nanotube and embedded materials play the roles of a gun barrel and bullets, respectively, to produce highly collimated and quasimonoenergetic proton beams. Three-dimensional particle simulations, that take all the two-body Coulomb interactions into account, demonstrate generation of quasimonoenergetic 1.5-MeV proton beams under a super-intense electrostatic field ~ 1014 V m-1.

  12. Solid-state proton conductors

    SciTech Connect

    Jewulski, J.R.; Osif, T.L.; Remick, R.J.

    1990-12-01

    The purpose of this program was to survey the field of solid-state proton conductors (SSPC), identify conductors that could be used to develop solid-state fuel cells suitable for use with coal derived fuel gases, and begin the experimental research required for the development of these fuel cells. This document covers the following topics: the history of developments and current status of the SSPC, including a review of proton conducting electrolyte structures, the current status of the medium temperature SSPC development, electrodes for moderate temperature (SSPC) fuel cell, basic material and measurement techniques applicable for SSPC development, modeling and optimization studies. Correlation and optimization studies, to include correlation studies on proton conduction and oxide cathode optimization for the SSPC fuel cell. Experiments with the SSPC fuel cells including the fabrication of the electrolyte disks, apparatus for conducting measurements, the strontium-cerium based electrolyte, the barium-cerium based electrolyte with solid foil electrodes, the barium-cerium based electrolyte with porous electrodes, and conduction mechanisms. 164 refs., 27 figs., 13 tabs.

  13. Heavy-quarkonium production in high energy proton-proton collisions at RHIC

    SciTech Connect

    Brodsky, Stanley J.; Lansberg, Jean-Philippe

    2010-03-01

    We update the study of the total {psi} and {Upsilon} production cross section in proton-proton collisions at RHIC energies using the QCD-based color-singlet model, including next-to-leading order partonic matrix elements. We also include charm-quark initiated processes which appear at leading order in {alpha}{sub s}, so far overlooked in such studies. Contrary to earlier claims, we show that the color-singlet yield is consistent with measurements over a broad range of J/{psi} rapidities. We find that intrinsic plus sealike charm-initiated processes contribute more than 20% of the direct J/{psi} yield. The key signature for such processes is the observation of a charm-quark jet opposite in azimuthal angle {phi} to the detected J/{psi}. Our results have impact on the proper interpretation of heavy-quarkonium production in heavy-ion collisions and its use as a probe for the quark-gluon plasma.

  14. Hydrogen-bonded proton transfer in the protonated guanine-cytosine (GC+H)+ base pair.

    PubMed

    Lin, Yuexia; Wang, Hongyan; Gao, Simin; Schaefer, Henry F

    2011-10-13

    The single proton transfer at the different sites of the Watson-Crick (WC) guanine-cytosine (GC) DNA base pair are studied here using density functional methods. The conventional protonated structures, transition state (TS) and proton-transferred product (PT) structures of every relevant species are optimized. Each transition state and proton-transferred product structure has been compared with the corresponding conventional protonated structure to demonstrate the process of proton transfer and the change of geometrical structures. The relative energies of the protonated tautomers and the proton-transfer energy profiles in gas and solvent are analyzed. The proton-transferred product structure G(+H(+))-H(+)C(N3)(-H(+))(PT) has the lowest relative energy for which only two hydrogen bonds exist. Almost all 14 isomers of the protonated GC base pair involve hydrogen-bonded proton transfer following the three pathways, with the exception of structure G-H(+)C(O2). When the positive charge is primarily "located" on the guanine moiety (H(+)G-C, G-H(+)C(C4), and G-H(+)C(C6)), the H(1) proton transfers from the N(1) site of guanine to the N(3) site of cytosine. The structures G-H(+)C(C5) and G-H(+)C(C4) involve H(4a) proton transfer from the N(4) of cytosine to the O(6) site of guanine. H(2a) proton transfer from the N(2) site of guanine to the O(2) site of cytosine is found only for the structure G-H(+)C(C4). The structures to which a proton is added on the six-centered sites adjoining the hydrogen bonds are more prone to proton transfer in the gas phase, whereas a proton added on the minor groove and the sites adjoining the hydrogen bonds is favorable to the proton transfer in energy in the aqueous phase.

  15. A beam source model for scanned proton beams

    NASA Astrophysics Data System (ADS)

    Kimstrand, Peter; Traneus, Erik; Ahnesjö, Anders; Grusell, Erik; Glimelius, Bengt; Tilly, Nina

    2007-06-01

    A beam source model, i.e. a model for the initial phase space of the beam, for scanned proton beams has been developed. The beam source model is based on parameterized particle sources with characteristics found by fitting towards measured data per individual beam line. A specific aim for this beam source model is to make it applicable to the majority of the various proton beam systems currently available or under development, with the overall purpose to drive dose calculations in proton beam treatment planning. The proton beam phase space is characterized by an energy spectrum, radial and angular distributions and deflections for the non-modulated elementary pencil beam. The beam propagation through the scanning magnets is modelled by applying experimentally determined focal points for each scanning dimension. The radial and angular distribution parameters are deduced from measured two-dimensional fluence distributions of the elementary beam in air. The energy spectrum is extracted from a depth dose distribution for a fixed broad beam scan pattern measured in water. The impact of a multi-slab range shifter for energy modulation is calculated with an own Monte Carlo code taking multiple scattering, energy loss and straggling, non-elastic and elastic nuclear interactions in the slab assembly into account. Measurements for characterization and verification have been performed with the scanning proton beam system at The Svedberg Laboratory in Uppsala. Both in-air fluence patterns and dose points located in a water phantom were used. For verification, dose-in-water was calculated with the Monte Carlo code GEANT 3.21 instead of using a clinical dose engine with approximations of its own. For a set of four individual pencil beams, both with the full energy and range shifted, 96.5% (99.8%) of the tested dose points satisfied the 1%/1 mm (2%/2 mm) gamma criterion.

  16. A beam source model for scanned proton beams.

    PubMed

    Kimstrand, Peter; Traneus, Erik; Ahnesjö, Anders; Grusell, Erik; Glimelius, Bengt; Tilly, Nina

    2007-06-01

    A beam source model, i.e. a model for the initial phase space of the beam, for scanned proton beams has been developed. The beam source model is based on parameterized particle sources with characteristics found by fitting towards measured data per individual beam line. A specific aim for this beam source model is to make it applicable to the majority of the various proton beam systems currently available or under development, with the overall purpose to drive dose calculations in proton beam treatment planning. The proton beam phase space is characterized by an energy spectrum, radial and angular distributions and deflections for the non-modulated elementary pencil beam. The beam propagation through the scanning magnets is modelled by applying experimentally determined focal points for each scanning dimension. The radial and angular distribution parameters are deduced from measured two-dimensional fluence distributions of the elementary beam in air. The energy spectrum is extracted from a depth dose distribution for a fixed broad beam scan pattern measured in water. The impact of a multi-slab range shifter for energy modulation is calculated with an own Monte Carlo code taking multiple scattering, energy loss and straggling, non-elastic and elastic nuclear interactions in the slab assembly into account. Measurements for characterization and verification have been performed with the scanning proton beam system at The Svedberg Laboratory in Uppsala. Both in-air fluence patterns and dose points located in a water phantom were used. For verification, dose-in-water was calculated with the Monte Carlo code GEANT 3.21 instead of using a clinical dose engine with approximations of its own. For a set of four individual pencil beams, both with the full energy and range shifted, 96.5% (99.8%) of the tested dose points satisfied the 1%/1 mm (2%/2 mm) gamma criterion.

  17. Protons @ interfaces: implications for biological energy conversion.

    PubMed

    Mulkidjanian, Armen Y; Heberle, Joachim; Cherepanov, Dmitry A

    2006-08-01

    The review focuses on the anisotropy of proton transfer at the surface of biological membranes. We consider (i) the data from "pulsed" experiments, where light-triggered enzymes capture or eject protons at the membrane surface, (ii) the electrostatic properties of water at charged interfaces, and (iii) the specific structural attributes of proton-translocating enzymes. The pulsed experiments revealed that proton exchange between the membrane surface and the bulk aqueous phase takes as much as about 1 ms, but could be accelerated by added mobile pH-buffers. Since the accelerating capacity of the latter decreased with the increase in their electric charge, it was concluded that the membrane surface is separated from the bulk aqueous phase by a barrier of electrostatic nature. The barrier could arise owing to the water polarization at the negatively charged membrane surface. The barrier height depends linearly on the charge of penetrating ions; for protons, it has been estimated as about 0.12 eV. While the proton exchange between the surface and the bulk aqueous phase is retarded by the interfacial barrier, the proton diffusion along the membrane, between neighboring enzymes, takes only microseconds. The proton spreading over the membrane is facilitated by the hydrogen-bonded networks at the surface. The membrane-buried layers of these networks can eventually serve as a storage/buffer for protons (proton sponges). As the proton equilibration between the surface and the bulk aqueous phase is slower than the lateral proton diffusion between the "sources" and "sinks", the proton activity at the membrane surface, as sensed by the energy transducing enzymes at steady state, might deviate from that measured in the adjoining water phase. This trait should increase the driving force for ATP synthesis, especially in the case of alkaliphilic bacteria.

  18. The investigation of physical conditions of boron uptake region in proton boron fusion therapy (PBFT)

    NASA Astrophysics Data System (ADS)

    Jung, Joo-Young; Yoon, Do-Kun; Lee, Heui Chang; Lu, Bo; Suh, Tae Suk

    2016-09-01

    We conducted a quantitative study to identify the effectiveness of proton boron fusion therapy (PBFT). Four simulation scenarios were designed to investigate the escalation in total dose with the proton boron reaction using a Monte Carlo n-particle extended (MCNPX 2.6.0) simulation. The peak integrated dose was obtained for three different physical conditions (i.e., boron uptake region (BUR) thickness, BUR location, and boron concentration) with differing proton beam energy (60-90 MeV). We found that the peak integrated dose was increased by up to 96.62% compared to the pristine proton Bragg-peak. For the synergetic effect to take place with 60-70 MeV proton beam, the BUR had to be at least 0.3 cm thick while spanning the Bragg-peak. Similarly to the thickness, the BUR location needed to be within 0.3 cm from the Bragg-peak when the thickness was maintained at 0.9 cm. An effective proton boron reaction required the boron concentration to be equal to or greater than 14.4 mg/g. These results demonstrate the impact of various physical and beam conditions of the PBFT, which are critical environmental factors for the treatment planning. We envision that this study will advance our understanding of the PBFT, which can be an invaluable treatment method for maximizing the potential of proton therapy.

  19. Deficiency in Homologous Recombination Renders Mammalian Cells More Sensitive to Proton Versus Photon Irradiation

    SciTech Connect

    Grosse, Nicole; Fontana, Andrea O.; Hug, Eugen B.; Lomax, Antony; Coray, Adolf; Augsburger, Marc; Paganetti, Harald; Sartori, Alessandro A.; Pruschy, Martin

    2014-01-01

    Purpose: To investigate the impact of the 2 major DNA repair machineries on cellular survival in response to irradiation with the 2 types of ionizing radiation. Methods and Materials: The DNA repair and cell survival endpoints in wild-type, homologous recombination (HR)-deficient, and nonhomologous end-joining-deficient cells were analyzed after irradiation with clinically relevant, low-linear energy transfer (LET) protons and 200-keV photons. Results: All cell lines were more sensitive to proton irradiation compared with photon irradiation, despite no differences in the induction of DNA breaks. Interestingly, HR-deficient cells and wild-type cells with small interfering RNA-down-regulated Rad51 were markedly hypersensitive to proton irradiation, resulting in an increased relative biological effectiveness in comparison with the relative biological effectiveness determined in wild-type cells. In contrast, lack of nonhomologous end-joining did not result in hypersensitivity toward proton irradiation. Repair kinetics of DNA damage in wild-type cells were equal after both types of irradiation, although proton irradiation resulted in more lethal chromosomal aberrations. Finally, repair kinetics in HR-deficient cells were significantly delayed after proton irradiation, with elevated amounts of residual γH2AX foci after irradiation. Conclusion: Our data indicate a differential quality of DNA damage by proton versus photon irradiation, with a specific requirement for homologous recombination for DNA repair and enhanced cell survival. This has potential relevance for clinical stratification of patients carrying mutations in the DNA damage response pathways.

  20. {beta}-delayed proton decays near the proton drip line

    SciTech Connect

    Xu, S.-W.; Li, Z.-K.; Xie, Y.-X.; Pan, Q.-Y.; Huang, W.-X.; Wang, X.-D.; Yu, Y.; Xing, Y.-B.; Shu, N.-C.; Chen, Y.-S.; Xu, F.-R.; Wang, K.

    2005-05-01

    We briefly reviewed and summarized the experimental study on {beta}-delayed proton decays published by our group over the last 8 years, namely the experimental observation of {beta}-delayed proton decays of nine new nuclides in the rare-earth region near the proton drip line and five nuclides in the mass 90 region with N{approx}Z by utilizing the p-{gamma} coincidence technique in combination with a He-jet tape transport system. In addition, important technical details of the experiments were provided. The experimental results were compared to the theoretical predictions of some nuclear models, resulting in the following conclusions. (1) The experimental half-lives for {sup 85}Mo, {sup 92}Rh, as well as the predicted 'waiting point' nuclei {sup 89}Ru and {sup 93}Pd were 5-10 times longer than the macroscopic-microscopic model predictions of Moeller et al. [At. Data Nucl. Data Tables 66,131(1997)]. These data considerably influenced the predictions of the mass abundances of the nuclides produced in the rp process. (2) The experimental assignments of spin and parity for the drip-line nuclei {sup 142}Ho and {sup 128}Pm could not be well predicted by any of the nuclear models. Nevertheless, the configuration-constrained nuclear potential-energy surfaces calculated by means of a Woods-Saxon-Strutinsky method could reproduce the assignments. (3) The ALICE code overestimated by one or two orders of magnitude the production-reaction cross sections of the nine studied rare-earth nuclei, while the HIVAP code overestimated them by approximately one order of magnitude.

  1. Database for inelastic collisions of sodium atoms with electrons, protons, and multiply charged ions

    SciTech Connect

    Igenbergs, K.; Schweinzer, J.; Bray, I.; Bridi, D.; Aumayr, F.

    2008-11-15

    The available experimental and theoretical cross section data for inelastic collision processes of ground (3s) and excited (3p, 4s, 3d, 4p, 5s, 4d, and 4f) state Na atoms with electrons, protons, and multiply charged ions have been collected and critically assessed. In addition to existing data, electron-impact cross sections, for both excitation and ionization, have been calculated using the convergent close-coupling approach. In the case of proton-impact cross section, the database was enlarged by new atomic-orbital close-coupling calculations. Both electron-impact and proton-impact processes include excitation from the ground state and between excited states (n = 3-5). For electron-impact, ionization from all states is also considered. In the case of proton-impact electron loss, cross sections (the sum of ionization and single-electron charge transfer) are given. Well-established analytical formulae used to fit cross sections, published by Wutte et al. and Schweinzer et al. for collisions with lithium atoms, were adapted to sodium. The 'recommended cross sections' for the processes considered have been critically evaluated and fitted using the adapted analytical formulae. For each inelastic process the fit parameters determined are tabulated. We also present the assessed data in graphical form. The criteria for comprehensively evaluating the accuracy of the experimental data, theoretical calculations, and procedures used in determining the recommended cross sections are discussed.

  2. Electron- and proton-induced ionization of pyrimidine

    SciTech Connect

    Champion, Christophe; Quinto, Michele; Weck, Philippe F

    2015-03-27

    This present work describes a quantum-mechanically based model of the electron- and proton-induced ionization of isolated pyrimidine molecules. The impact energies range from the target ionization threshold up to ~1 keV for electrons and from 10 keV up to 10 MeV for protons. The cross-section calculations are performed within the 1st Born approximation in which the ejected electron is described by a Coulomb wave whereas the incident and the scattered projectiles are both described by plane waves. The pyrimidine target is described using the Gaussian 09 software package. Furthermore, our theoretical predictions obtained are in good agreement with experimental absolute total cross sections, while large discrepancies are observed between existing semi-empirical models and the present calculations.

  3. Electron- and proton-induced ionization of pyrimidine

    DOE PAGES

    Champion, Christophe; Quinto, Michele; Weck, Philippe F

    2015-03-27

    This present work describes a quantum-mechanically based model of the electron- and proton-induced ionization of isolated pyrimidine molecules. The impact energies range from the target ionization threshold up to ~1 keV for electrons and from 10 keV up to 10 MeV for protons. The cross-section calculations are performed within the 1st Born approximation in which the ejected electron is described by a Coulomb wave whereas the incident and the scattered projectiles are both described by plane waves. The pyrimidine target is described using the Gaussian 09 software package. Furthermore, our theoretical predictions obtained are in good agreement with experimental absolutemore » total cross sections, while large discrepancies are observed between existing semi-empirical models and the present calculations.« less

  4. Noncontact dipole effects on channel permeation. III. Anomalous proton conductance effects in gramicidin

    PubMed Central

    Phillips, LR; Cole, CD; Hendershot, RJ; Cotten, M; Cross, TA; Busath, DD

    1999-01-01

    Proton transport on water wires, of interest for many problems in membrane biology, is analyzed in side-chain analogs of gramicidin A channels. In symmetrical 0.1 N HCl solutions, fluorination of channel Trp(11), Trp-(13), or Trp(15) side chains is found to inhibit proton transport, and replacement of one or more Trps with Phe enhances proton transport, the opposite of the effects on K(+) transport in lecithin bilayers. The current-voltage relations are superlinear, indicating that some membrane field-dependent process is rate limiting. The interfacial dipole effects are usually assumed to affect the rate of cation translocation across the channel. For proton conductance, however, water reorientation after proton translocation is anticipated to be rate limiting. We propose that the findings reported here are most readily interpreted as the result of dipole-dipole interactions between channel waters and polar side chains or lipid headgroups. In particular, if reorientation of the water column begins with the water nearest the channel exit, this hypothesis explains the negative impact of fluorination and the positive impact of headgroup dipole on proton conductance. PMID:20540928

  5. Assessment of Proton Deflectometry for Exploding Wire Experiments

    SciTech Connect

    Beg, Farhat Nadeem

    2013-09-25

    This project provides the first demonstration of the application of proton deflectometry for the diagnosis of electromagnetic field topology and current-carrying regions in Z-pinch plasma experiments. Over the course of this project several milestones were achieved. High-energy proton beam generation was demonstrated on the short-pulse high-intensity Leopard laser, (10 Joules in ~350 femtoseconds, and the proton beam generation was shown to be reproducible. Next, protons were used to probe the electromagnetic field structure of short circuit loads in order to benchmark the two numerical codes, the resistive-magnetohydrodynamics (MHD) code, Gorgon, and the hybrid particle-in-cell code, LSP for the interpretation of results. Lastly, the proton deflectometry technique was used to map the magnetic field structure of pulsed-power-driven plasma loads including wires and supersonic jets formed with metallic foils. Good agreement between the modeling and experiments has been obtained. The demonstrated technique holds great promise to significantly improve the understanding of current flow and electromagnetic field topology in pulsed power driven high energy density plasmas. Proton probing with a high intensity laser was for the first time implemented in the presence of the harsh debris and x-ray producing z-pinch environment driven by a mega-ampere-scale pulsed-power machine. The intellectual merit of the program was that it investigated strongly driven MHD systems and the influence of magnetic field topology on plasma evolution in pulsed power driven plasmas. The experimental program involved intense field-matter interaction in the generation of the proton probe, as well as the generation of plasma subjected to 1 MegaGauss scale magnetic fields. The computational aspect included two well-documented codes, in combination for the first time to provide accurate interpretation of the experimental results. The broader impact included the support of 2 graduate students, one at

  6. Proton Diffusion Coefficient in Electrospun Hybrid Membranes by Electrochemical Impedance Spectroscopy.

    PubMed

    Dos Santos, Leslie; Laberty-Robert, Christel; Maréchal, Manuel; Perrot, Hubert; Sel, Ozlem

    2015-09-15

    Electrochemical Impedance Spectroscopy (EIS) was, for the first time, used to estimate the global transverse proton diffusion coefficient, D(H+)(EHM), in electrospun hybrid conducting membranes (EHMs). In contrast to conventional impedance spectroscopy, EIS measurements were performed at room temperature with a liquid interface. In this configuration, the measure of the bulk proton transport is influenced by the kinetics of the transfer of proton at the solid/liquid interface. We demonstrated that the use of additives in the process of the membrane impacts the organization of the hydrophilic domains and also the proton transport. The D(H+)(EHM) is close to 1.10(-7) cm(2) s(-1) (± 0.1.10(-7) cm(2) s(-1)) for the EHMs without additive, whereas it is 4.10(-6) cm(2) s(-1) (± 0.4.10(-6) cm(2) s(-1)) for EHMs with additives.

  7. Model independent extraction of the proton magnetic radius from electron scattering

    NASA Astrophysics Data System (ADS)

    Epstein, Zachary; Paz, Gil; Roy, Joydeep

    2014-10-01

    We combine constraints from analyticity with experimental electron-proton scattering data to determine the proton magnetic radius without model-dependent assumptions on the shape of the form factor. We also study the impact of including electron-neutron scattering data, and ππ→NN ¯ data. Using representative data sets we find for a cut of Q2≤0.5 GeV2, rMp=0.91-0.06+0.03±0.02 fm using just proton scattering data; rMp=0.87-0.05+0.04±0.01 fm adding neutron data; and rMp=0.87-0.02+0.02 fm adding ππ data. We also extract the neutron magnetic radius from these data sets obtaining rMn=0.89-0.03+0.03 fm from the combined proton, neutron, and ππ data.

  8. Neutron-Proton Pairing Effect on One-Proton and Two-Proton Separation Energies in Rare-Earth Proton-Rich Nuclei

    NASA Astrophysics Data System (ADS)

    Hammache, F.; Allal, N. H.; Fellah, M.

    2012-12-01

    The one-proton and two-proton separation energies are studied for "ordinary" and rare-earth proton-rich nuclei by including the isovector neutron-proton (np) pairing correlations using the BCS approximation. Even-even as well as odd nuclei are considered. In the latter case, the wave function is defined using the blocked-level technique. The single-particle energies used are those of a deformed Woods-Saxon mean field. It is shown that the np isovector pairing effects on the one-proton and two-proton separation energies are non-negligible. However, the only isovector BCS approximation seems to be inadequate for a good description of these quantities when including the np pairing effects: either a particle-number projection or the inclusion of the isoscalar pairing effect seems to be necessary. Another possible improvement would be a more realistic choice of the pairing strengths.

  9. Commissioning of the PRIOR proton microscope.

    PubMed

    Varentsov, D; Antonov, O; Bakhmutova, A; Barnes, C W; Bogdanov, A; Danly, C R; Efimov, S; Endres, M; Fertman, A; Golubev, A A; Hoffmann, D H H; Ionita, B; Kantsyrev, A; Krasik, Ya E; Lang, P M; Lomonosov, I; Mariam, F G; Markov, N; Merrill, F E; Mintsev, V B; Nikolaev, D; Panyushkin, V; Rodionova, M; Schanz, M; Schoenberg, K; Semennikov, A; Shestov, L; Skachkov, V S; Turtikov, V; Udrea, S; Vasylyev, O; Weyrich, K; Wilde, C; Zubareva, A

    2016-02-01

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5-4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This paper describes the PRIOR setup as well as the results of the first static and dynamic proton radiography experiments performed at GSI. PMID:26931841

  10. Commissioning of the PRIOR proton microscope

    NASA Astrophysics Data System (ADS)

    Varentsov, D.; Antonov, O.; Bakhmutova, A.; Barnes, C. W.; Bogdanov, A.; Danly, C. R.; Efimov, S.; Endres, M.; Fertman, A.; Golubev, A. A.; Hoffmann, D. H. H.; Ionita, B.; Kantsyrev, A.; Krasik, Ya. E.; Lang, P. M.; Lomonosov, I.; Mariam, F. G.; Markov, N.; Merrill, F. E.; Mintsev, V. B.; Nikolaev, D.; Panyushkin, V.; Rodionova, M.; Schanz, M.; Schoenberg, K.; Semennikov, A.; Shestov, L.; Skachkov, V. S.; Turtikov, V.; Udrea, S.; Vasylyev, O.; Weyrich, K.; Wilde, C.; Zubareva, A.

    2016-02-01

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5-4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This paper describes the PRIOR setup as well as the results of the first static and dynamic proton radiography experiments performed at GSI.

  11. Mechanisms of proton pumping in bacteriorhodopsin

    SciTech Connect

    Ebrey, T.G.

    1991-01-01

    The purple membrane of Halobacterium halobium probably represents the simplest biological solar energy conversion system. Light absorbed by bacteriorhodopsin directly leads to the transport of protons across the cell membrane. The resulting chemosmotic potential can be used to make ATP. An additional feature of the purple membrane is its ability to pump protons over a wide variety of salt concentration including in extreme saline environments. This project investigates the relationship between the transport of protons across the membrane and structure and conformation of bacteriorhodospin. We have proposed experiments to study the pH dependence of proton pumping. Secondly, we are examining the role of divalent cations and the effect of the large surface potential of the purple membrane on the proton pumping function of this membrane using the photocurrents associated with the pumping process. Finally we are studying the role of proteinatable amino acids in proton transport. 16 refs.

  12. Inhibitors of proton pumping: effect on passive proton transport.

    PubMed

    Bisson, M A

    1986-05-01

    Reported inhibitors of the Characean plasmalemma proton pump were tested for their ability to inhibit the passive H(+) conductance which develops in Chara corallina Klein ex Willd. at high pH. Diethylstilbestrol inhibits the proton pump and the passive H(+) conductance with about the same time course, at concentrations that have no effect on cytoplasmic streaming. N-Ethylmaleimide, a sulfhydryl reagent which is small and relatively nonpolar, also inhibits both pumping and passive conductance of H(+). However, it also inhibits cytoplasmic streaming with about the same time course, and therefore could not be considered a specific ATPase inhibitor. p-Chloromercuribenzene sulfonate (PCMBS), a sulfhydryl reagent which is large and charged and hence less able to penetrate the membrane, does not inhibit pumping or conductance at low concentration. At high concentration, PCMBS sometimes inhibits pumping without affecting H(+) conductance, but since streaming is also inhibited, the effect on the pump cannot be said to be specific. 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide, a water soluble carbodiimide, weakly inhibits both pump and conductance, apparently specifically.

  13. Molecular Mechanism of Biological Proton Transport

    SciTech Connect

    Pomes, R.

    1998-09-01

    Proton transport across lipid membranes is a fundamental aspect of biological energy transduction (metabolism). This function is mediated by a Grotthuss mechanism involving proton hopping along hydrogen-bonded networks embedded in membrane-spanning proteins. Using molecular simulations, the authors have explored the structural, dynamic, and thermodynamic properties giving rise to long-range proton translocation in hydrogen-bonded networks involving water molecules, or water wires, which are emerging as ubiquitous H{sup +}-transport devices in biological systems.

  14. The spin structure of the proton

    SciTech Connect

    Bass, Steven D.

    2005-10-15

    This article reviews the present understanding of the QCD spin structure of the proton. The author first outlines the proton spin puzzle and its possible resolution in QCD. Then the review explores the present and next generation of experiments being undertaken to resolve the proton's spin-flavor structure, explaining the theoretical issues involved, the present status of experimental investigation, and the open questions and challenges for future investigation.

  15. Molecular mechanisms for generating transmembrane proton gradients.

    PubMed

    Gunner, M R; Amin, Muhamed; Zhu, Xuyu; Lu, Jianxun

    2013-01-01

    Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side.

  16. Molecular mechanisms for generating transmembrane proton gradients.

    PubMed

    Gunner, M R; Amin, Muhamed; Zhu, Xuyu; Lu, Jianxun

    2013-01-01

    Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side. PMID:23507617

  17. Magnets for high intensity proton synchrotrons

    SciTech Connect

    Jean-Francois Ostiguy, Vladimir Kashikhine and Alexander Makarov

    2002-09-19

    Recently, there has been considerable interest at Fermilab for the Proton Driver, a future high intensity proton machine. Various scenarios are under consideration, including a superconducting linac. Each scenario present some special challenges. We describe here the magnets proposed in a recent study, the Proton Driver Study II, which assumes a conventional warm synchrotron, roughly of the size of the existing FNAL booster, but capable of delivering 380 kW at 8 GeV.

  18. Compact Proton Accelerator for Cancer Therapy

    SciTech Connect

    Chen, Y; Paul, A C

    2007-06-12

    An investigation is being made into the feasibility of making a compact proton dielectric wall (DWA) accelerator for medical radiation treatment based on the high gradient insulation (HGI) technology. A small plasma device is used for the proton source. Using only electric focusing fields for transporting and focusing the beam on the patient, the compact DWA proton accelerator m system can deliver wide and independent variable ranges of beam currents, energies and spot sizes.

  19. An observation of proton-induced latchup

    NASA Technical Reports Server (NTRS)

    Nichols, Donald K.; Coss, James R.; Watson, R. K.; Schwartz, Harvey R.; Pease, Ronald L.

    1992-01-01

    Proton-induced latchup in a CMOS microprocessor known to have a very low heavy-ion-induced latchup threshold LET was observed. The latchup cross section vs. proton energy for three different bias conditions is displayed. Average measures of latchup current within an 11-ms window following the onset of latchup are provided, as a function of bias and incident proton energy. These data can be interpreted in terms of the present understanding of SEE phenomena.

  20. Acid, protons and Helicobacter pylori.

    PubMed Central

    Sachs, G.; Meyer-Rosberg, K.; Scott, D. R.; Melchers, K.

    1996-01-01

    The anti-ulcer drugs that act as covalent inhibitors of the gastric acid pump are targeted to the gastric H+/K+ ATPase by virtue of accumulation in acid and conversion to the active sulfenamide. This results in extremely effective inhibition of acid secretion. Appropriate dosage is able to optimize acid control therapy for reflux and peptic ulcer disease as compared to H2 receptor antagonists. However, clinical data on recurrence show that Helicobacter pylori eradication should accompany treatment of the lesion. These drugs have been found to synergize with many antibiotics for eradication. The survival of aerobes depends on their ability to maintain a driving force for protons across their inner membrane, the sum of a pH and potential difference gradient, the protonmotive force (pmf). The transmembrane flux of protons across the F1F0 ATPase, driven by the pmf, is coupled to the synthesis of ATP. The internal pH of H. pylori was measured using the fluorescent dye probe, BCECF, and the membrane potential defined by the uptake of the carbocyanine dye, DiSC3 [5] at different pHs to mimic the gastric environment. The protonmotive force at pH 7.0 was composed of a delta pH of 1.4 (-84mV) and a delta potential difference of -131mV, to give a pmf of -215 mV. The effect of variations in external pH on survival of the bacteria in the absence of urea correlated with the effect of external pH on the ability of the bacteria to maintain a pmf. The effect of the addition of 5 mM urea on the pmf was measured at different medium pH values. Urea restored the pmf at pH 3.0 or 3.5, but abolished the pmf at pH 7.0 or higher, due the production of the alkalinizing cation, NH3. Hence H. pylori is an acid-tolerant neutrophile due to urease activity, but urease activity also limits its survival to an acidic environment. These data help explain the occupation of the stomach by the organism and its distribution between fundus and antrum. This distribution and its alteration by proton pump

  1. Proton beam therapy control system

    DOEpatents

    Baumann, Michael A; Beloussov, Alexandre V; Bakir, Julide; Armon, Deganit; Olsen, Howard B; Salem, Dana

    2013-06-25

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  2. Proton beam therapy control system

    DOEpatents

    Baumann, Michael A.; Beloussov, Alexandre V.; Bakir, Julide; Armon, Deganit; Olsen, Howard B.; Salem, Dana

    2008-07-08

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  3. Proton beam therapy control system

    DOEpatents

    Baumann, Michael A.; Beloussov, Alexandre V.; Bakir, Julide; Armon, Deganit; Olsen, Howard B.; Salem, Dana

    2010-09-21

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  4. Proton beam therapy control system

    DOEpatents

    Baumann, Michael A; Beloussov, Alexandre V; Bakir, Julide; Armon, Deganit; Olsen, Howard B; Salem, Dana

    2013-12-03

    A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

  5. Proton and heavy ion therapy.

    PubMed

    Larsson, B

    1975-01-01

    Penetrating ion beams are considered interesting supplements to the types of radiation, mostly electrons and gamma rays, that have dominated in radiation research and radiotherapy during the last decades. Biomedical experimentations and clinical studies ar larger ion accelerators (100-1000 MeV/amu) are therefore undertaken in order to exploit their possible clinical use in cancer therapy. It is concluded that an accelerator that permits effective use of protons (ca. 200 MeV) and deutrons (ca. 50 MeV, for neutron therapy) located in a central hospital would represent a convenient tool for clinical investigations at a larger scale. PMID:1201773

  6. Proton decay studies at HRIBF

    SciTech Connect

    Batchelder, J.C.; Bingham, C.R.; Rykaczewski, K.; Toth, K.S.; Mas, J.F.; McConnell, J.W.; Yu, C.; Bingham, C.R.; Grzywacz, R.; Kim, S.H.; Weintraub, W.; Rykaczewski, K.; Janas, Z.; Karny, M.; Davinson, T.; Slinger, R.C.; Woods, P.J.; Ginter, T.N.; Gross, C.J.; MacDonald, B.D.; Piechaczek, A.; Zganjar, E.F.; Ressler, J.J.; Walters, W.B.; Szerypo, J.

    1998-12-01

    A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {mu}sec. In this paper we present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu. {copyright} {ital 1998 American Institute of Physics.}

  7. Multiparticle production in deep inelastic lepton scattering and soft proton proton collisions

    SciTech Connect

    Werner, K.

    1987-06-01

    We demonstrate how the theoretical knowledge about multiparticle production in deep inelastic lepton scattering can be incorporated into a multistring model for low p/sub t/ proton proton collisions. 25 refs., 8 figs.

  8. Transverse relaxation of scalar-coupled protons.

    PubMed

    Segawa, Takuya F; Baishya, Bikash; Bodenhausen, Geoffrey

    2010-10-25

    In a preliminary communication (B. Baishya, T. F. Segawa, G. Bodenhausen, J. Am. Chem. Soc. 2009, 131, 17538-17539), we recently demonstrated that it is possible to obtain clean echo decays of protons in biomolecules despite the presence of homonuclear scalar couplings. These unmodulated decays allow one to determine apparent transverse relaxation rates R(2) (app) of individual protons. Herein, we report the observation of R(2) (app) for three methyl protons, four amide H(N) protons, and all 11 backbone H(α) protons in cyclosporin A. If the proton resonances overlap, their R(2) (app) rates can be measured by transferring their magnetization to neighboring (13)C nuclei, which are less prone to overlap. The R(2) (app) rates of protons attached to (13)C are faster than those attached to (12)C because of (13)C-(1)H dipolar interactions. The differences of these rates allow the determination of local correlation functions. Backbone H(N) and H(α) protons that have fast decay rates R(2) (app) also feature fast longitudinal relaxation rates R(1) and intense NOESY cross peaks that are typical of crowded environments. Variations of R(2) (app) rates of backbone H(α) protons in similar amino acids reflect differences in local environments.

  9. Cascaded proton acceleration by collisionless electrostatic shock

    NASA Astrophysics Data System (ADS)

    Xu, T. J.; Shen, B. F.; Zhang, X. M.; Yi, L. Q.; Wang, W. P.; Zhang, L. G.; Xu, J. C.; Zhao, X. Y.; Shi, Y.; Liu, C.; Pei, Z. K.

    2015-07-01

    A new scheme for proton acceleration by cascaded collisionless electrostatic shock (CES) is proposed. By irradiating a foil target with a moderate high-intensity laser beam, a stable CES field can be induced, which is employed as the accelerating field for the booster stage of proton acceleration. The mechanism is studied through simulations and theoretical analysis, showing that a 55 MeV seed proton beam can be further accelerated to 265 MeV while keeping a good energy spread. This scheme offers a feasible approach to produce proton beams with energy of hundreds of MeV by existing available high-intensity laser facilities.

  10. Cascaded proton acceleration by collisionless electrostatic shock

    SciTech Connect

    Xu, T. J.; Shen, B. F. E-mail: zhxm@siom.ac.cn; Zhang, X. M. E-mail: zhxm@siom.ac.cn; Yi, L. Q.; Wang, W. P.; Zhang, L. G.; Xu, J. C.; Zhao, X. Y.; Shi, Y.; Liu, C.; Pei, Z. K.

    2015-07-15

    A new scheme for proton acceleration by cascaded collisionless electrostatic shock (CES) is proposed. By irradiating a foil target with a moderate high-intensity laser beam, a stable CES field can be induced, which is employed as the accelerating field for the booster stage of proton acceleration. The mechanism is studied through simulations and theoretical analysis, showing that a 55 MeV seed proton beam can be further accelerated to 265 MeV while keeping a good energy spread. This scheme offers a feasible approach to produce proton beams with energy of hundreds of MeV by existing available high-intensity laser facilities.

  11. Catalytic asymmetric protonation of lithium enolates using amino acid derivatives as chiral proton sources.

    PubMed

    Mitsuhashi, Kaori; Ito, Rie; Arai, Takayoshi; Yanagisawa, Akira

    2006-04-13

    [reaction: see text] Asymmetric protonation of lithium enolates was examined using commercially available amino acid derivatives as chiral proton sources. Among the amino acid derivatives tested, Nbeta-l-aspartyl-l-phenylalanine methyl ester was found to cause significant asymmetric induction in the protonation of lithium enolates. The enantiomeric excess (up to 88% ee) of the products obtained in the presence of a catalytic amount of the chiral proton source was higher than those obtained in the stoichiometric reaction. PMID:16597150

  12. Method study of parameter choice for a circular proton-proton collider

    NASA Astrophysics Data System (ADS)

    Su, Feng; Gao, Jie; Xiao, Ming; Wang, Dou; Wang, Yi-Wei; Bai, Sha; Bian, Tian-Jian

    2016-01-01

    In this paper we show a systematic method of appropriate parameter choice for a circular proton-proton collider by using an analytical expression for the beam-beam tune shift limit, starting from a given design goal and technical limitations. A suitable parameter space has been explored. Based on the parameter scan, sets of appropriate parameters designed for a 50 km and 100 km circular proton-proton collider are proposed. Supported by National Natural Science Foundation of China (11175192)

  13. Catalytic asymmetric protonation of lithium enolates using amino acid derivatives as chiral proton sources.

    PubMed

    Mitsuhashi, Kaori; Ito, Rie; Arai, Takayoshi; Yanagisawa, Akira

    2006-04-13

    [reaction: see text] Asymmetric protonation of lithium enolates was examined using commercially available amino acid derivatives as chiral proton sources. Among the amino acid derivatives tested, Nbeta-l-aspartyl-l-phenylalanine methyl ester was found to cause significant asymmetric induction in the protonation of lithium enolates. The enantiomeric excess (up to 88% ee) of the products obtained in the presence of a catalytic amount of the chiral proton source was higher than those obtained in the stoichiometric reaction.

  14. Three-body Coulomb dynamics in hydrogen ionization by protons and antiprotons at intermediate collision velocities

    NASA Astrophysics Data System (ADS)

    Voitkiv, A. B.; Ullrich, J.

    2003-06-01

    We consider ionization of atomic hydrogen with emission of low-energy electrons by proton and antiproton impact in the range of impact velocities 3 a.u.⩽vp⩽6 a.u., where the electron capture by protons is already of minor importance but the differences in hydrogen ionization due to proton and antiproton impact can still be substantial. By calculating various differential cross sections within the first and second Born and continuum-distorted-wave eikonal-initial-state (CDW-EIS) approximations we attempt to analyze the dynamics of hydrogen ionization by protons and antiprotons. We discuss in some detail the role of (i) the interaction between the projectile and the target nucleus and (ii) multiphoton exchanges between the projectile and the target electron. Profound charge-sign effects are suggested by CDW-EIS and second Born calculations for the fully differential emission pattern. Although after the integration over the electron emission angles these effects substantially diminish, they still remain noticeable even in the total ionization cross section suggesting, in particular, that protons are more effective, compared to antiprotons, in producing soft electron emission from hydrogen in the range of collision velocities under consideration.

  15. Ionization of water by (20-150)-keV protons: Separation of direct-ionization and electron-capture processes

    SciTech Connect

    Gobet, F.; Eden, S.; Coupier, B.; Tabet, J.; Farizon, B.; Farizon, M.; Gaillard, M.J.; Carre, M.; Ouaskit, S.; Maerk, T. D.; Scheier, P.

    2004-12-01

    Mass analyzed product ions have been detected in coincidence with the projectile following the ionization of water by proton impact. Measurement of the projectile charge state postcollision enables the different ionization processes to be identified: direct ionization, single electron capture, and double electron capture. A complete set of partial and total absolute cross sections is reported for the direct ionization and electron capture processes initiated by proton collisions at 20-150 keV. The cross sections for the direct ionization of H{sub 2}O by proton impact are compared with previous electron impact results [Straub et al., J. Chem. Phys. 108, 109 (1998)].

  16. Measurement of proton and anti-proton intensities in the Tevatron Collider

    SciTech Connect

    Stephen Pordes et al.

    2003-06-04

    This paper describes the techniques used to measure the intensities of the proton (p) and anti-proton ({bar p}) beams in the Tevatron collider. The systems provide simultaneous measurements of the intensity of the 36 proton and 36 antiproton bunches and their longitudinal profiles.

  17. Parameterization of spectral distributions for pion and kaon production in proton-proton collisions

    NASA Technical Reports Server (NTRS)

    Schneider, John P.; Norbury, John W.; Cucinotta, Frank A.

    1995-01-01

    Accurate semi-empirical parameterizations of the energy-differential cross sections for charged pion and kaon production from proton-proton collisions are presented at energies relevant to cosmic rays. The parameterizations depend on the outgoing meson momentum and also the proton energy, and are able to be reduced to very simple analytical formulas suitable for cosmic-ray transport.

  18. Forward Proton Detection at Dø

    NASA Astrophysics Data System (ADS)

    Rangel, Murilo

    2006-04-01

    Quantum Chromo-Dynamics (QCD) has been a very successful model describing the strong interaction, but its success has been limited primarily to the perturbative regime. About 40% of the total proton-antiproton cross section at the Tevatron consists of the non-perturbative processes of elastic and diffractive scattering. These processes are better described by the phenomenology of a color singlet exchange of a particle with quantum numbers of the vacuum called the pomeron (Regge theory). The D0 experiment (http://www-d0.fnal.gov) is currently taking data with a forward proton detector (FPD) to better study this process. The FPD data is being used to study the diffractive phenomenology, which has attracted both experimental and theoretical attention. This data provides a unique opportunity to study many topics in the diffractive regime, for instance events which contain a double pomeron exchange. This talk will present FPD data acquired during the last year, focusing on the methods for eliminating background and noise and emphasizing the detector capabilities to explore this interesting physics regime.

  19. PROTONATED POLYCYCLIC AROMATIC HYDROCARBONS REVISITED

    SciTech Connect

    Ricca, Alessandra; Bauschlicher, Charles W. Jr; Allamandola, Louis J. E-mail: Charles.W.Bauschlicher@nasa.gov

    2011-02-01

    We reconsider the contribution that singly protonated polycyclic aromatic hydrocarbons (PAHs; HPAH{sup +}s) might make to the Class A component of the 6.2 {mu}m interstellar emission feature in light of the recent experimental measurements of protonated naphthalene and coronene. Our calculations on the small HPAH{sup +}s have a band near 6.2 {mu}m, as found in experiment. While the larger HPAH{sup +}s still have emission near 6.2 {mu}m, the much larger intensity of the band near 6.3 {mu}m overwhelms the weaker band at 6.2 {mu}m, so that the 6.2 {mu}m band is barely visible. Since the large PAHs are more representative of those in the interstellar medium, our work suggests that large HPAH{sup +}s cannot be major contributors to the observed emission at 6.2 {mu}m (i.e., Class A species). Saturating large PAH cations with hydrogen atoms retains the 6.2 {mu}m Class A band position, but the rest of the spectrum is inconsistent with observed spectra.

  20. MCNP5 for proton radiography.

    SciTech Connect

    Hughes, H. G.; Brown, F. B.; Bull, J. S.; Goorley, J. T.; Little, R. C.; Liu, L. C.; Mashnik, S. G.; Prael, R. E.; Selcow, Elizabeth Carol,; Sierk, A. J.; Sweezy, J. E.; Zumbro, J. D.; Mokhov, N. V.; Striganov, S.; Gudima, K. K.

    2004-01-01

    The developmental version of MCNPS has recently been extended to provide for continuous-energy transport of high-energy protons. This enhancement involves the incorporation of several significant new physics models into the code. Multiple Coulomb scattering is treated with an advanced model that takes account of projectile and nuclear target form factors. In the next version, this model will provide a coupled sampling of both angular deflection and collisional energy loss, including straggling. The proton elastic scattering model is also new, based on recent theoretical work. Charged particle transport in the presence of magnetic fields is accomplished either by using transfer maps from the COSY INFINITY code (in void regions) or by using an algorithm adapted from the MARS code (in void regions or in scattering materials). Work is underway to validate and implement the latest versions of the Cascade-Exciton Model and the Los Alamos Quark-Gluon-String Model, which will process inelastic nuclear interactions and generate secondary particles.

  1. New interplanetary proton fluence model

    NASA Technical Reports Server (NTRS)

    Feynman, Joan; Armstrong, T. P.; Dao-Gibner, L.; Silverman, S.

    1990-01-01

    A new predictive engineering model for the interplanetary fluence of protons with above 10 MeV and above 30 MeV is described. The data set used is a combination of observations made from the earth's surface and from above the atmosphere between 1956 and 1963 and observations made from spacecraft in the vicinity of earth between 1963 and 1985. The data cover a time period three times as long as the period used in earlier models. With the use of this data set the distinction between 'ordinary proton events' and 'anomalously large events' made in earlier work disappears. This permitted the use of statistical analysis methods developed for 'ordinary events' on the entire data set. The greater than 10 MeV fluences at 1 AU calculated with the new model are about twice those expected on the basis of models now in use. At energies above 30 MeV, the old and new models agree. In contrast to earlier models, the results do not depend critically on the fluence from any one event and are independent of sunspot number. Mission probability curves derived from the fluence distribution are presented.

  2. M2 Proton Channel: Toward a Model of a Primitive Proton Pump

    NASA Astrophysics Data System (ADS)

    Wei, Chenyu; Pohorille, Andrew

    2015-06-01

    Transmembrane proton transfer was essential to early cellular systems in order to transduce energy for metabolic functions. The reliable, efficient and controlled generation of proton gradients became possible only with the emergence of active proton pumps. On the basis of features shared by most modern proton pumps we identify the essential mechanistic steps in active proton transport. Further, we discuss the mechanism of action of a small, transmembrane M2 proton channel from influenza A virus as a model for proton transport in protocells. The M2 channel is a 94-residue long, α-helical tetramer that is activated at low pH and exhibits high selectivity and directionality. A shorter construct, built of transmembrane fragments that are only 24 amino acids in length, exhibits very similar proton transport properties. Molecular dynamics simulations on the microsecond time-scale carried out for the M2 channel provided atomic level details on the activation of the channel in response to protonation of the histidine residue, His37. The pathway of proton conduction is mediated by His37, which accepts and donates protons at different interconverting conformation states when pH is lower than 6.5. The Val27 and Trp41 gates and the salt bridge between Asp44 and Arg45 further enhance the directionality of proton transport. It is argued that the architecture and the mechanism of action similar to that found in the M2 channel might have been the perfect starting point for evolution towards the earliest proton pumps, indicating that active proton transport could have readily emerged from simple, passive proton channels.

  3. Collision dynamics of proton with formaldehyde: Fragmentation and ionization

    SciTech Connect

    Wang, Jing; Gao, Cong-Zhang; Calvayrac, Florent; Zhang, Feng-Shou

    2014-03-28

    Using time-dependent density functional theory, applied to the valence electrons and coupled non-adiabatically to molecular dynamics of the ions, we study the ionization and fragmentation of formaldehyde in collision with a proton. Four different impact energies: 35 eV, 85 eV, 135 eV, and 300 eV are chosen in order to study the energy effect in the low energy region, and ten different incident orientations at 85 eV are considered for investigating the steric effect. Fragmentation ratios, single, double, and total electron ionization cross sections are calculated. For large impact parameters, these results are close to zero irrespective of the incident orientations due to a weak projectile-target interaction. For small impact parameters, the results strongly depend on the collision energy and orientation. We also give the kinetic energy releases and scattering angles of protons, as well as the cross section of different ion fragments and the corresponding reaction channels.

  4. Proton-Induced Collisions on Potential Prebiotic Species

    NASA Astrophysics Data System (ADS)

    Bacchus-Montabonel, Marie-Christine

    2016-03-01

    With regard to the fascinating question of the origin of life, special interest has been devoted to potential prebiotic molecules which could drive the emergence of life. In the widely discussed hypothesis of a possible exogen apparition of life, the transport of those prebiotic species and their survival under spatial conditions is of strong interest. In particular their stability under solar radiation or in collisions with bare nucleus has to be considered. In that sense, taking account of the abundance of protons in ionized clouds of the interstellar medium, we have developed a detailed theoretical study of the charge transfer collision dynamics induced by impact of protons on a series of possible prebiotic compounds. Three main types of molecules have been considered: first of all the DNA and RNA building blocks with on a one hand the nucleobases uracil and thymine, and on the other hand the 2-deoxy-D-ribose sugar skeleton in its furanose and pyranose forms. The study has been extended to the 2-aminooxazole suggested to be a possible precursor of RNA nucleotides. The theoretical treatment involves ab-initio quantum chemistry molecular calculations followed by a semiclassical collision dynamics. Some qualitative trends may be suggested for the proton-induced damage of such prebiotic species.

  5. Proton-Induced Collisions on Potential Prebiotic Species

    NASA Astrophysics Data System (ADS)

    Bacchus-Montabonel, Marie-Christine

    2016-11-01

    With regard to the fascinating question of the origin of life, special interest has been devoted to potential prebiotic molecules which could drive the emergence of life. In the widely discussed hypothesis of a possible exogen apparition of life, the transport of those prebiotic species and their survival under spatial conditions is of strong interest. In particular their stability under solar radiation or in collisions with bare nucleus has to be considered. In that sense, taking account of the abundance of protons in ionized clouds of the interstellar medium, we have developed a detailed theoretical study of the charge transfer collision dynamics induced by impact of protons on a series of possible prebiotic compounds. Three main types of molecules have been considered: first of all the DNA and RNA building blocks with on a one hand the nucleobases uracil and thymine, and on the other hand the 2-deoxy-D-ribose sugar skeleton in its furanose and pyranose forms. The study has been extended to the 2-aminooxazole suggested to be a possible precursor of RNA nucleotides. The theoretical treatment involves ab-initio quantum chemistry molecular calculations followed by a semiclassical collision dynamics. Some qualitative trends may be suggested for the proton-induced damage of such prebiotic species.

  6. Revealing dressed quarks via the proton's charge distribution.

    PubMed

    Cloët, Ian C; Roberts, Craig D; Thomas, Anthony W

    2013-09-01

    The proton is arguably the most fundamental of nature's readily detectable building blocks. It is at the heart of every nucleus and has never been observed to decay. It is nevertheless a composite object, defined by its valence-quark content: u+u+d--i.e., two up (u) quarks and one down (d) quark; and the manner by which they influence, inter alia, the distribution of charge and magnetization within this bound state. Much of novelty has recently been learned about these distributions; and it now appears possible that the proton's momentum-space charge distribution possesses a zero. Experiments in the coming decade should answer critical questions posed by this and related advances; we explain how such new information may assist in charting the origin and impact of key emergent phenomena within the strong interaction. Specifically, we show that the possible existence and location of a zero in the proton's electric form factor are a measure of nonperturbative features of the quark-quark interaction in the standard model, with particular sensitivity to the running of the dressed-quark mass.

  7. Proton Transport in Carbonic Anhydrase: Insights from Molecular Simulation

    PubMed Central

    Maupin, C. Mark; Voth, Gregory A.

    2009-01-01

    Summary This article reviews the insights gained from molecular simulations of human carbonic anhydrase II (HCA II) utilizing non-reactive and reactive force fields. The simulations with a reactive force field explore protein transfer and transport via Grotthuss shuttling, while the non-reactive simulations probe the larger conformational dynamics that underpin the various contributions to the rate-limiting proton transfer event. Specific attention is given to the orientational stability of the His64 group and the characteristics of the active site water cluster, in an effort to determine both of their impact on the maximal catalytic rate. The explicit proton transfer and transport events are described by the multistate empirical valence bond (MS-EVB) method, as are alternative pathways for the excess proton charge defect to enter/leave the active site. The simulation results are interpreted in light of experimental results on the wild-type enzyme and various site-specific mutations of HCA II in order to better elucidate the key factors that contribute to its exceptional efficiency. PMID:19765680

  8. On proton CT reconstruction using MVCT-converted virtual proton projections

    SciTech Connect

    Wang Dongxu; Mackie, T. Rockwell; Tome, Wolfgang A.

    2012-06-15

    Purpose: To describe a novel methodology of converting megavoltage x-ray projections into virtual proton projections that are otherwise missing due to the proton range limit. These converted virtual proton projections can be used in the reconstruction of proton computed tomography (pCT). Methods: Relations exist between proton projections and multispectral megavoltage x-ray projections for human tissue. Based on these relations, these tissues can be categorized into: (a) adipose tissue; (b) nonadipose soft tissues; and (c) bone. These three tissue categories can be visibly identified on a regular megavoltage x-ray computed tomography (MVCT) image. With an MVCT image and its projection data available, the x-ray projections through heterogeneous anatomy can be converted to the corresponding proton projections using predetermined calibration curves for individual materials, aided by a coarse segmentation on the x-ray CT image. To show the feasibility of this approach, mathematical simulations were carried out. The converted proton projections, plotted on a proton sinogram, were compared to the simulated ground truth. Proton stopping power images were reconstructed using either the virtual proton projections only or a blend of physically available proton projections and virtual proton projections that make up for those missing due to the range limit. These images were compared to a reference image reconstructed from theoretically calculated proton projections. Results: The converted virtual projections had an uncertainty of {+-}0.8% compared to the calculated ground truth. Proton stopping power images reconstructed using a blend of converted virtual projections (48%) and physically available projections (52%) had an uncertainty of {+-}0.86% compared with that reconstructed from theoretically calculated projections. Reconstruction solely from converted virtual proton projections had an uncertainty of {+-}1.1% compared with that reconstructed from theoretical projections

  9. A coarse-graining approach for the proton complex in protonated aluminosilicates.

    PubMed

    Calero, S; Lobato, M D; García-Pérez, E; Mejías, J A; Lago, S; Vlugt, T J H; Maesen, T L M; Smit, B; Dubbeldam, D

    2006-03-30

    We have developed a computational framework for the adsorption of linear alkanes in protonated aluminosilicates. These zeolites contain trace amounts of water that form hydrated proton complexes. The presence of hydrated protons makes the simulations at the fully atomistic level difficult. Instead of constructing an elaborate and complex model, we show that an approach based on a coarse-graining of the proton-complex accurately describes the available experimental isotherms, Henry coefficients, heats of adsorption, and oxygen-proton distances. Our approach is supported by MP2 quantum mechanical simulations. The model gives remarkably good agreement with experimental data beyond the initial calibration set.

  10. BEAM SCRUBBING FOR RHIC POLARIZED PROTON RUN.

    SciTech Connect

    ZHANG,S.Y.FISCHER,W.HUANG,H.ROSER,T.

    2004-07-05

    One of the intensity limiting factor of RHIC polarized proton beam is the electron cloud induced pressure rise. A beam scrubbing study shows that with a reasonable period of time of running high intensity 112-bunch proton beam, the pressure rise can be reduced, allowing higher beam intensity.

  11. Ring current proton decay by charge exchange

    NASA Technical Reports Server (NTRS)

    Smith, P. H.; Hoffman, R. A.; Fritz, T.

    1975-01-01

    Explorer 45 measurements during the recovery phase of a moderate magnetic storm have confirmed that the charge exchange decay mechanism can account for the decay of the storm-time proton ring current. Data from the moderate magnetic storm of 24 February 1972 was selected for study since a symmetrical ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, the equatorially mirroring protons in the energy range 5 to 30 keV decayed throughout the L-value range of 3.5 to 5.0 at the charge exchange decay rate calculated by Liemohn. After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange can entirely account for the storm-time proton ring current decay, and that this mechanism must be considered in all studies involving the loss of proton ring current particles.

  12. Reduced Calibration Curve for Proton Computed Tomography

    SciTech Connect

    Yevseyeva, Olga; Assis, Joaquim de; Diaz, Katherin

    2010-05-21

    The pCT deals with relatively thick targets like the human head or trunk. Thus, the fidelity of pCT as a tool for proton therapy planning depends on the accuracy of physical formulas used for proton interaction with thick absorbers. Although the actual overall accuracy of the proton stopping power in the Bethe-Bloch domain is about 1%, the analytical calculations and the Monte Carlo simulations with codes like TRIM/SRIM, MCNPX and GEANT4 do not agreed with each other. A tentative to validate the codes against experimental data for thick absorbers bring some difficulties: only a few data is available and the existing data sets have been acquired at different initial proton energies, and for different absorber materials. In this work we compare the results of our Monte Carlo simulations with existing experimental data in terms of reduced calibration curve, i.e. the range - energy dependence normalized on the range scale by the full projected CSDA range for given initial proton energy in a given material, taken from the NIST PSTAR database, and on the final proton energy scale - by the given initial energy of protons. This approach is almost energy and material independent. The results of our analysis are important for pCT development because the contradictions observed at arbitrary low initial proton energies could be easily scaled now to typical pCT energies.

  13. Proton Therapy Research and Treatment Center

    SciTech Connect

    Goodnight, J.E. Jr. . Cancer Center); Alonso, J.R. )

    1992-05-01

    This Grant proposal outlines the steps that will be undertaken to bring the UC Davis Proton Therapy Research and Treatment, known locally as the Proton Therapy Facility (PTF), through its design and construction phases. This application concentrates on the design phase of the PTF project.

  14. CONFIGURATION MANUAL POLARIZED PROTON COLLIDER AT RHIC.

    SciTech Connect

    ROSER,T.; MACKAY,W.W.; ALEKSEEV,I.; BAI,M.; BROWN,K.; BUNCE,G.; CAMERON,P.; COURANT,E.; ET AL.

    2001-03-01

    In this report, the authors present their design to accelerate and store polarized protons in RHIC, with the level of polarization, luminosity, and control of systematic errors required by the approved RHIC spin physics program. They provide an overview of the physics to be studied using RHIC with polarized proton beams, and a brief description of the accelerator systems required for the project.

  15. Physics at an upgraded Fermilab proton driver

    SciTech Connect

    Geer, S.; /Fermilab

    2005-07-01

    In 2004 the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future, primarily motivated by the recent exciting developments in neutrino physics. Over the last few months a physics study has developed the physics case for the Fermilab Proton Driver. The potential physics opportunities are discussed.

  16. Chemical Principles Revisited. Proton Magnetic Resonance Spectroscopy.

    ERIC Educational Resources Information Center

    McQuarrie, Donald A.

    1988-01-01

    Discusses how to interpret nuclear magnetic resonance (NMR) spectra and how to use them to determine molecular structures. This discussion is limited to spectra that are a result of observation of only the protons in a molecule. This type is called proton magnetic resonance (PMR) spectra. (CW)

  17. On the high energy proton spectrum measurements

    NASA Technical Reports Server (NTRS)

    Ellsworth, R. W.; Ito, A.; Macfall, J.; Siohan, F.; Streitmatter, R. E.; Tonwar, S. C.; Vishwanath, P. R.; Yodh, G. B.; Balasubrahmanyan, V. K.

    1977-01-01

    The steepening of the proton spectrum beyond 1000 GeV and the rise in inelastic cross sections between 20 and 600 GeV observed by the PROTON-1-2-3 satellite experiments were explained by systematic effects of energy dependent albedo (backscatter) from the calorimeter.

  18. Configuration Manual Polarized Proton Collider at RHIC

    SciTech Connect

    Alekseev, I.; Allgower, C.; Bai, M.; Batygin, Y.; Bozano, L.; Brown, K.; Bunce, G.; Cameron, P.; Courant, E.; Erin, S.; Escallier, J.; Fischer, W.; Gupta, R.; Hatanka, K.; Huang, H.; Imai, K.; Ishihara, M.; Jain, A.; Kanavets, V.; Katayama, T.; Kawaguchi, T.; Kelly, E.; Kurita, K.; Lee, S. Y.; Luccio, A.; MacKay, W. W.; Mahler, G.; Makdisi, Y.; Mariam, F.; McGahern, W.; Morgan, G.; Muratore, J.; Okamura, M.; Peggs, S.; Pilat, F.; Ptitsin, V.; Ratner, L.; Roser, T.; Saito, N.; Satoh, H.; Shatunov, Y.; Spinka, H.; Svirida, D.; Syphers, M.; Tepikian, S.; Tominaka, T.; Tsoupas, N.; Underwood, D.; Vasiliev, A.; Wanderer, P.; Willen, E.; Wu, H.; Yokosawa, A.; Zelenski, A.

    2006-01-01

    In this report we present our design to accelerate and store polarized protons in RHIC, with the level of polarization, luminosity, and control of systematic errors required by the approved RHIC spin physics program. We provide an overview of the physics to be studied using RHIC with polarized proton beams, and a brief description of the accelerator systems required for the project.

  19. Protic Salt Polymer Membranes: High-Temperature Water-Free Proton-Conducting Membranes

    SciTech Connect

    Gervasio, Dominic Francis

    2010-09-30

    This research on proton-containing (protic) salts directly addresses proton conduction at high and low temperatures. This research is unique, because no water is used for proton ionization nor conduction, so the properties of water do not limit proton fuel cells. A protic salt is all that is needed to give rise to ionized proton and to support proton mobility. A protic salt forms when proton transfers from an acid to a base. Protic salts were found to have proton conductivities that are as high as or higher than the best aqueous electrolytes at ambient pressures and comparable temperatures without or with water present. Proton conductivity of the protic salts occurs providing two conditions exist: i) the energy difference is about 0.8 eV between the protic-salt state versus the state in which the acid and base are separated and 2) the chemical constituents rotate freely. The physical state of these proton-conducting salts can be liquid, plastic crystal as well as solid organic and inorganic polymer membranes and their mixtures. Many acids and bases can be used to make a protic salt which allows tailoring of proton conductivity, as well as other properties that affect their use as electrolytes in fuel cells, such as, stability, adsorption on catalysts, environmental impact, etc. During this project, highly proton conducting (~ 0.1S/cm) protic salts were made that are stable under fuel-cell operating conditions and that gave highly efficient fuel cells. The high efficiency is attributed to an improved oxygen electroreduction process on Pt which was found to be virtually reversible in a number of liquid protic salts with low water activity (< 1% water). Solid flexible non-porous composite membranes, made from inorganic polymer (e.g., 10%indium 90%tin pyrophosphate, ITP) and organic polymer (e.g., polyvinyl pyridinium phosphate, PVPP), were found that give conductivity and fuel cell performances similar to phosphoric acid electrolyte with no need for hydration at

  20. Interstitial-Mediated Diffusion in Germanium under Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Bracht, H.; Schneider, S.; Klug, J. N.; Liao, C. Y.; Hansen, J. Lundsgaard; Haller, E. E.; Larsen, A. Nylandsted; Bougeard, D.; Posselt, M.; Wündisch, C.

    2009-12-01

    We report experiments on the impact of 2.5 MeV proton irradiation on self-diffusion and dopant diffusion in germanium (Ge). Self-diffusion under irradiation reveals an unusual depth independent broadening of the Ge isotope multilayer structure. This behavior and the observed enhanced diffusion of B and retarded diffusion of P demonstrates that an interstitial-mediated diffusion process dominates in Ge under irradiation. This fundamental finding opens up unique ways to suppress vacancy-mediated diffusion in Ge and to solve the donor deactivation problem that hinders the fabrication of Ge-based nanoelectronic devices.

  1. Proton Transport in Imidazoles: Unraveling the Role of Supramolecular Structure

    DOE PAGES

    Cosby, James T.; Holt, Adam P.; Griffin, Phillip; Wang, Yangyang; Sangoro, Joshua R.

    2015-09-18

    The impact of supramolecular hydrogen bonded networks on dynamics and charge transport in 2-ethyl-4-methylimidazole (2E4MIm), a model proton-conducting system, is investigated by broadband dielectric spectroscopy, depolarized dynamic light scattering, viscometry, and calorimetry. It is observed that the slow, Debye-like relaxation reflecting the supramolecular structure in neat 2E4MIm is eliminated upon the addition of minute amounts of levulinic acid. This is attributed to the dissociation of imidazole molecules and the breaking down of hydrogen-bonded chains, which leads to a 10-fold enhancement of ionic conductivity.

  2. MO-A-18C-01: Proton Therapy I: Basics of Proton Therapy

    SciTech Connect

    Arjomandy, B; Sahoo, N; Pankuch, M

    2014-06-15

    The goal of this session is to introduce the audience to the physics, dosimetry and treatment planning procedures used in proton therapy. The course material covers the basic physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for scattered and scanning proton beams. It will include the requirements for dosimetry measurements and present the equipment needed for commissioning of proton beams for clinical use and quality assurance checks as well as methods used for proton beam calibration and dose verification of patient treatment fields. The session covers the treatment planning strategies for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. Challenges involved in the motion management in proton therapy will also be discussed. Learning Objectives: Gain knowledge on physics, dosimetry, treatment planning and quality assurance for proton therapy. Understand the uncertainties associated with proton therapy and currently used strategies for their mitigation in treatment planning.

  3. Proton conducting ceramic membranes for hydrogen separation

    DOEpatents

    Elangovan, S.; Nair, Balakrishnan G.; Small, Troy; Heck, Brian

    2011-09-06

    A multi-phase proton conducting material comprising a proton-conducting ceramic phase and a stabilizing ceramic phase. Under the presence of a partial pressure gradient of hydrogen across the membrane or under the influence of an electrical potential, a membrane fabricated with this material selectively transports hydrogen ions through the proton conducting phase, which results in ultrahigh purity hydrogen permeation through the membrane. The stabilizing ceramic phase may be substantially structurally and chemically identical to at least one product of a reaction between the proton conducting phase and at least one expected gas under operating conditions of a membrane fabricated using the material. In a barium cerate-based proton conducting membrane, one stabilizing phase is ceria.

  4. Commissioning of the PRIOR proton microscope

    DOE PAGES

    Varentsov, D.; Antonov, O.; Bakhmutova, A.; Barnes, C. W.; Bogdanov, A.; Danly, C. R.; Efimov, S.; Endres, M.; Fertman, A.; Golubev, A. A.; et al

    2016-02-18

    Recently, a new high energy proton microscopy facility PRIOR (Proton Microscope for FAIR Facility for Anti-proton and Ion Research) has been designed, constructed, and successfully commissioned at GSI Helmholtzzentrum für Schwerionenforschung (Darmstadt, Germany). As a result of the experiments with 3.5–4.5 GeV proton beams delivered by the heavy ion synchrotron SIS-18 of GSI, 30 μm spatial and 10 ns temporal resolutions of the proton microscope have been demonstrated. A new pulsed power setup for studying properties of matter under extremes has been developed for the dynamic commissioning of the PRIOR facility. This study describes the PRIOR setup as well asmore » the results of the first static and dynamic protonradiography experiments performed at GSI.« less

  5. Fine structure in deformed proton emitters.

    SciTech Connect

    Sonzogni, A. A.; Davids, C. N.; Woods, P. J.; Seweryniak, D.; Carpenter, M. P.; Ressler, J. J.; Schwartz, J.; Uusitalo, J.; Walters, W. B.

    1999-12-07

    In a recent experiment to study the proton radioactivity of the highly deformed {sup 131}Eu nucleus, two proton lines were detected. The higher energy one was assigned to the ground-state to ground-state decay, while the lower energy, to the ground-state to the 2{sup +} state decay. This constitutes the first observation of fine structure in proton radioactivity. With these four measured quantities, proton energies, half-life and branching ratio, it is possible to determine the Nilsson configuration of the ground state of the proton emitting nucleus as well as the 2{sup +} energy and nuclear deformation of the daughter nucleus. These results will be presented and discussed.

  6. Pointing of laser-accelerated proton beams

    SciTech Connect

    Schreiber, J.; Ter-Avetisyan, S.; Risse, E.; Kalachnikov, M.P.; Nickles, P.V.; Sandner, W.; Schramm, U.; Habs, D.; Witte, J.; Schnuerer, M.

    2006-03-15

    Small fluctuations in the acceleration sheath change the pointing of a proton beam accelerated from the rear side of a laser irradiated thin aluminum foil. The proton acceleration was produced with 40 fs pulses of a Ti:sapphire laser at an intensity of approximately 10{sup 19} W/cm{sup 2}. This observation has been made with a high spatial resolution Thomson spectrometer. The proton beam pointing has appeared stable in the energy range between the high energy cutoff (3 MeV) and 50% of this value. Deviations of the beam position at lower energies changes in a range of 0-3 mrad. The recorded pictures show wiggled and continuous proton traces which imply a release of the proton beam from the acceleration zone with a velocity chirp.

  7. Electron cloud simulations of a proton storage ring using cold proton bunches

    NASA Astrophysics Data System (ADS)

    Sato, Y.; Holmes, J.; Lee, S. Y.; Macek, R.

    2008-02-01

    Using the ORBIT code we study the sensitivity of electron cloud properties with respect to different proton beam profiles, the secondary electron yield (SEY) parameter, and the proton loss rate. Our model uses a cold proton bunch to generate primary electrons and electromagnetic field for electron cloud dynamics. We study the dependence of the prompt and swept electron signals vs the bunch charge and the recovery of electron clouds after sweeping on the beam loss rate and the SEY. The simulation results are compared with the experimental data measured at the proton storage ring at the Los Alamos National Laboratory. Our simulations indicate that the fractional proton loss rate in the field-free straight section may be an exponential function of proton beam charge and may also be lower than the averaged fractional proton loss rate over the whole ring.

  8. Aconitase: its source of catalytic protons.

    PubMed

    Kuo, D J; Rose, I A

    1987-12-01

    An ordinary isotope partition experiment was performed to determine the rate of dissociation of the proton from the donor site for the hydration of cis-aconitate. Aconitase in [3H]water was efficiently diluted into well-mixed solutions of cis-aconitate. Citrate and isocitrate that were formed within 2 s were more heavily labeled than could be explained by consideration of an isotope effect in the processing of one proton per enzyme equivalent. Control experiments indicate that mixing was much more rapid than catalytic turnover, ruling out incompletely diluted [3H]water as a significant isotope source. Therefore, it appears that significantly more than one enzyme-bound tritium atom (protons) must have been used in the course of the multiple turnover of the enzyme after the dilution was complete. Isotope incorporation reached values in excess of four proton equivalents as a limit with simple Michaelis dependence on cis-aconitate. From the half-saturation concentration value for trapping, 0.15 mM, the t 1/2 for exchange of each of these protons with solvent appears to be approximately 0.1 s at 0 degrees C. The large number of protons trapped seems to suggest the existence of a structurally stabilized pool of protons, or water, that communicates between the active site base and the medium in the hydration of cis-aconitate. The proton abstracted in the dehydration of [3H]citrate is transferred directly to undissociated cis-aconitate to form isocitrate without dilution, or cis-aconitate having dissociated, the tritium passes to the medium, presumably through the pool of bound protons indicated above. All of the citrate-derived protons can be found in isocitrate if cis-aconitate is added in sufficient concentration.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2827757

  9. Proton Irradiation Creep in Pyrocarbon

    SciTech Connect

    Was, Gary S.; Campbell, Anne

    2011-10-01

    This project aims to understand irradiation creep in pyrocarbon using proton irradiation under controlled stresses and temperatures. Experiments will be conducted over a range of temperatures and stresses per the proposal submitted. The work scope will include the preparation of samples, measurement of deposition thickness, thickness uniformity, and anisotropy. The samples produced will be made in strips, which will be used for the creep experiments. Materials used will include pyrolytic carbon (PyC), Highly Oriented Pyrolytic Graphite (HOPG), or graphite strip samples in that order depending upon success. Temperatures tested under will range from 800°C to 1200°C, and stresses from 6MPa to 20.7MPa. Optional testing may occur at 900°C and 1100°C and stresses from 6MPa to 20.7MPa if funding is available.

  10. Liquid hydrogen in protonic chabazite.

    PubMed

    Zecchina, Adriano; Bordiga, Silvia; Vitillo, Jenny G; Ricchiardi, Gabriele; Lamberti, Carlo; Spoto, Giuseppe; Bjørgen, Morten; Lillerud, Karl Petter

    2005-05-01

    Due to its fully reversible nature, H(2) storage by molecular adsorption could represent an advantage with respect to dissociative processes, where kinetic effects during the charging and discharging processes are present. A drawback of this strategy is represented by the extremely weak interactions that require low temperature and high pressure. High surface area materials hosting polarizing sites can represent a viable way toward more favorable working conditions. Of these, in this contribution, we have studied hydrogen adsorption in a series of zeolites using volumetric techniques and infrared spectroscopy at 15 K. We have found that in H-SSZ-13 zeolite the cooperative role played by high surface area, internal wall topology, and presence of high binding energy sites (protons) allows hydrogen to densify inside the nanopores at favorable temperature and pressure conditions. PMID:15853343

  11. The "heartbeat of the proton"

    NASA Astrophysics Data System (ADS)

    Weisskopf, Victor F.

    Once Nino came to my office to tell me about his ideas of studying lepton pair production at PS. I was still not Director General, but Research Director at CERN. In addition to (e+e-) and (μ+μ-) pairs, he wanted to search for (e±μ∓) pairs as a signature of a new lepton carrying its own lepton number. He told me that if such a lepton existed with one GeV mass, it would have escaped detection in hadron accelerator experiments for two reasons: i) it would decay with a lifetime of order 10-11 sec and ii) because there is no π → μ mechanism for such a heavy new lepton: for its production a time-like photon would be needed. Time-like photons could be produced in hadronic interactions: for example in (bar{p}p) annihilation. This was before Lederman-Schwartz and Steinberger had discovered the two neutrinos. To think of a "sequential" Heavy Lepton and to work out the possible ways to get it in a hadron machine was for me extremely interesting Nino had just finished his first high precision work on the muon (g-2). It was some time after the Rochester Conference in 1960. I gave Nino the following suggestion: if you want to search for something so revolutionary as a Heavy Lepton carrying its own lepton number you should work out a proposal for a series of experiments where the study of lepton pairs (e+e-) and (μ+μ-) could be justified in terms of physics accepted by the community. In addition a high intensity antiproton beam was needed. He came later to tell me that he had two very good friends, both excellent engineers: Mario Morpurgo and Guido Petrucci. A very high intensity antiproton beam could be built to study the electromagnetic form factor of the proton in the time-like region. If the proton was "point-like" in the time-like region, the rate of time-like photons yielding (e+e-) and (μ+μ-) pairs could be accessible to experimental observation, thus allowing to establish some limits on the new Heavy Lepton mass, or to see it, via the (e±μ∓) channel. The

  12. Contemporary Proton Therapy Systems Adequately Protect Patients from Exposure to Stray Radiation

    NASA Astrophysics Data System (ADS)

    Newhauser, Wayne D.; Fontenot, Jonas D.; Taddei, Phillip J.; Mirkovic, Dragan; Giebeler, Annelise; Zhang, Rui; Mahajan, Anita; Kornguth, David; Stovall, Marilyn; Yepes, Pablo; Woo, Shiao; Mohan, Radhe

    2009-03-01

    Proton beam therapy has provided safe and effective treatments for a variety of adult cancers. In recent years, there has been increasing interest in utilizing proton therapy for pediatric cancers because it allows better sparing of healthy tissues. Minimizing exposures of normal tissues is especially important in children because they are highly susceptible to consequential late effects, including the development of a radiogenic second cancer, which may occur years or even decades after treatment of the first cancer. While the dosimetric advantage of therapeutic proton beams is well understood, relatively little attention has been paid to the whole-body exposure to stray neutron radiation that is inherent in proton therapy. In this report, we review the physical processes that lead to neutron exposures, discuss the potential for mitigating these exposures using advanced proton beam delivery systems, and present a comparative analysis of predicted second cancer incidence following various external beam therapies. In addition, we discuss uncertainties in the relative biological effectiveness of neutrons for carcinogenesis and the impact that these uncertainties have on second-cancer risk predictions for survivors of adult and childhood cancer who receive proton therapy.

  13. Contemporary Proton Therapy Systems Adequately Protect Patients from Exposure to Stray Radiation

    SciTech Connect

    Newhauser, Wayne D.; Fontenot, Jonas D.; Taddei, Phillip J.; Mirkovic, Dragan; Giebeler, Annelise; Zhang Rui; Mahajan, Anita; Kornguth, David; Stovall, Marilyn; Woo, Shiao; Mohan, Radhe; Yepes, Pablo

    2009-03-10

    Proton beam therapy has provided safe and effective treatments for a variety of adult cancers. In recent years, there has been increasing interest in utilizing proton therapy for pediatric cancers because it allows better sparing of healthy tissues. Minimizing exposures of normal tissues is especially important in children because they are highly susceptible to consequential late effects, including the development of a radiogenic second cancer, which may occur years or even decades after treatment of the first cancer. While the dosimetric advantage of therapeutic proton beams is well understood, relatively little attention has been paid to the whole-body exposure to stray neutron radiation that is inherent in proton therapy. In this report, we review the physical processes that lead to neutron exposures, discuss the potential for mitigating these exposures using advanced proton beam delivery systems, and present a comparative analysis of predicted second cancer incidence following various external beam therapies. In addition, we discuss uncertainties in the relative biological effectiveness of neutrons for carcinogenesis and the impact that these uncertainties have on second-cancer risk predictions for survivors of adult and childhood cancer who receive proton therapy.

  14. Contemporary Proton Therapy Systems Adequately Protect Patients from Exposure to Stray Radiation

    PubMed Central

    Newhauser, Wayne D.; Fontenot, Jonas D.; Taddei, Phillip J.; Mirkovic, Dragan; Giebeler, Annelise; Zhang, Rui; Mahajan, Anita; Kornguth, David; Stovall, Marilyn; Yepes, Pablo; Woo, Shiao; Mohan, Radhe

    2010-01-01

    Proton beam therapy has provided safe and effective treatments for a variety of adult cancers. In recent years, there has been increasing interest in utilizing proton therapy for pediatric cancers because it allows better sparing of healthy tissues. Minimizing exposures of normal tissues is especially important in children because they are highly susceptible to consequential late effects, including the development of a radiogenic second cancer, which may occur years or even decades after treatment of the first cancer. While the dosimetric advantage of therapeutic proton beams is well understood, relatively little attention has been paid to the whole-body exposure to stray neutron radiation that is inherent in proton therapy. In this report, we review the physical processes that lead to neutron exposures, discuss the potential for mitigating these exposures using advanced proton beam delivery systems, and present a comparative analysis of predicted second cancer incidence following various external beam therapies. In addition, we discuss uncertainties in the relative biological effectiveness of neutrons for carcinogenesis and the impact that these uncertainties have on second-cancer risk predictions for survivors of adult and childhood cancer who receive proton therapy. PMID:20844607

  15. Mesospheric Dynamical Changes Induced by the Solar Proton Events in October-November 2003

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; Roble, Raymond G.; Fleming, Eric L.

    2007-01-01

    The very large solar storms in October-November 2003 caused solar proton events (SPEs) at the Earth that impacted the upper atmospheric polar cap regions. The Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Model (TIME-GCM) was used to study the atmospheric dynamical influence of the solar protons that occurred in Oct-Nov 2003, the fourth largest period of SPEs measured in the past 40 years. The highly energetic solar protons caused ionization, as well as dissociation processes, and ultimately produced odd hydrogen (HOx) and odd nitrogen (NOy). Significant short-lived ozone decreases (10-70%) followed these enhancements of HOx and NOy and led to a cooling of most of the lower mesosphere. This cooling caused an atmospheric circulation change that led to adiabatic heating of the upper mesosphere. Temperature changes up to plus or minus 2.6 K were computed as well as wind (zonal, meridional, vertical) perturbations up to 20-25% of the background winds as a result of 22 the solar protons. The solar proton-induced mesospheric temperature and wind perturbations diminished over a period of 4-6 weeks after the SPEs. The Joule heating in the mesosphere, induced by the solar protons, was computed to be relatively insignificant for these solar storms with most of the temperature and circulation perturbations caused by ozone depletion in the sunlit hemisphere.

  16. Through-the-electrode model of a proton exchange membrane fuel cell with independently measured parameters

    SciTech Connect

    Weisbrod, K.R.; Grot, S.A.; Vanderborgh, N.E.

    1995-05-01

    A one dimensional model for a proton exchange membrane fuel cell was developed which makes use of independently measured parameters for predicting single cell performance. Optimization of catalyst layer formulation and properties are explored. Impact of temperature and cathode pressure upon system performance was investigated.

  17. Through-the-electrode model of a proton exchange membrane fuel cell with independently measured parameters

    SciTech Connect

    Weisbrod, K.R.; Grot, S.A.; Vandergborgh, N.E.

    1995-09-01

    A one dimensional model for a proton exchange membrane fuel cell was developed which makes use of independently measured parameters for predicting single cell performance. Optimization of catalyst layer formulation and properties are explored. Impact of temperature and cathode pressure upon system performance is investigated.

  18. Insights into proton-coupled electron transfer mechanisms of electrocatalytic H2 oxidation and production

    PubMed Central

    Horvath, Samantha; Fernandez, Laura E.; Soudackov, Alexander V.; Hammes-Schiffer, Sharon

    2012-01-01

    The design of molecular electrocatalysts for H2 oxidation and production is important for the development of alternative renewable energy sources that are abundant, inexpensive, and environmentally benign. Recently, nickel-based molecular electrocatalysts with pendant amines that act as proton relays for the nickel center were shown to effectively catalyze H2 oxidation and production. We developed a quantum mechanical approach for studying proton-coupled electron transfer processes in these types of molecular electrocatalysts. This theoretical approach is applied to a nickel-based catalyst in which phosphorous atoms are directly bonded to the nickel center, and nitrogen atoms of the ligand rings act as proton relays. The catalytic step of interest involves electron transfer between the nickel complex and the electrode as well as intramolecular proton transfer between the nickel and nitrogen atoms. This process can occur sequentially, with either the electron or proton transferring first, or concertedly, with the electron and proton transferring simultaneously without a stable intermediate. The electrochemical rate constants are calculated as functions of overpotential for the concerted electron-proton transfer reaction and the two electron transfer reactions in the sequential mechanisms. Our calculations illustrate that the concerted electron-proton transfer standard rate constant will increase as the equilibrium distance between the nickel and nitrogen atoms decreases and as the pendant amines become more flexible to facilitate the contraction of this distance with a lower energy penalty. This approach identifies the favored mechanisms under various experimental conditions and provides insight into the impact of substituents on the nitrogen and phosphorous atoms. PMID:22529352

  19. Insights into proton-coupled electron transfer mechanisms of electrocatalytic H2 oxidation and production

    SciTech Connect

    Horvath, S.; Fernandez, L. E.; Soudackov, A. V.; Hammes-Schiffer, S.

    2012-04-23

    The design of molecular electrocatalysts for H2 oxidation and production is important for the development of alternative renewable energy sources that are abundant, inexpensive, and environmentally benign. Recently nickel-based molecular electrocatalysts with pendant amines that act as proton relays for the nickel center were shown to effectively catalyze H2 oxidation and production. We developed a quantum mechanical approach for studying proton-coupled electron transfer processes in these types of molecular electrocatalysts. This theoretical approach is applied to a nickel-based catalyst in which phosphorous atoms are directly bonded to the nickel center and nitrogen atoms of the ligand rings act as proton relays. The cataly c step of interest involves electron transfer between the nickel complex and the electrode as well as intramolecular proton transfer between the nickel and nitrogen atoms. This process can occur sequentially, with either the electron or proton transferring first, or concertedly, with the electron and proton transferring simultaneously without a stable intermediate. The heterogeneous rate constants are calculated as functions of overpotential for the concerted electron-proton transfer reaction and the two electron transfer reactions in the sequential mechanisms. Our calculations illustrate that the concerted electron-proton transfer standard rate constant will increase as the equilibrium distance between the nickel and nitrogen atoms decreases and as the nitrogen atoms become more mobile to facilitate the contraction of this distance. This approach assists in the identification of the favored mechanisms under various experimental conditions and provides insight into the qualitative impact of substituents on the nitrogen and phosphorous atoms. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy

  20. Proton transfer through the water gossamer

    PubMed Central

    Hassanali, Ali; Giberti, Federico; Cuny, Jérôme; Kühne, Thomas D.; Parrinello, Michele

    2013-01-01

    The diffusion of protons through water is understood within the framework of the Grotthuss mechanism, which requires that they undergo structural diffusion in a stepwise manner throughout the water network. Despite long study, this picture oversimplifies and neglects the complexity of the supramolecular structure of water. We use first-principles simulations and demonstrate that the currently accepted picture of proton diffusion is in need of revision. We show that proton and hydroxide diffusion occurs through periods of intense activity involving concerted proton hopping followed by periods of rest. The picture that emerges is that proton transfer is a multiscale and multidynamical process involving a broader distribution of pathways and timescales than currently assumed. To rationalize these phenomena, we look at the 3D water network as a distribution of closed directed rings, which reveals the presence of medium-range directional correlations in the liquid. One of the natural consequences of this feature is that both the hydronium and hydroxide ion are decorated with proton wires. These wires serve as conduits for long proton jumps over several hydrogen bonds. PMID:23868853

  1. Updating the Jovian Proton Radiation Environment - 2015

    NASA Technical Reports Server (NTRS)

    Garrett, Henry; Martinez-Sierra, Luz Maria; Evans, Robin

    2015-01-01

    Since publication in 1983 by N. Divine and H. Garrett, the Jet Propulsion Laboratory's plasma and radiation models have been the design standard for NASA's missions to Jupiter. These models consist of representations of the cold plasma and electrons, the warm and auroral electrons and protons, and the radiation environment (electron, proton, and heavy ions). To date, however, the high-energy proton model has been limited to an L-shell of 12. With the requirement to compute the effects of the high energy protons and other heavy ions on the proposed Europa mission, the extension of the high energy proton model from approximately 12 L-shell to approximately 50 L-shell has become necessary. In particular, a model of the proton environment over that range is required to estimate radiation effects on the solar arrays for the mission. This study describes both the steps taken to extend the original Divine proton model out to an approximately 50 L-shell and the resulting model developed to accomplish that goal. In addition to hydrogen, the oxygen, sulfur, and helium heavy ion environments have also been added between approximately 6 L-shell and approximately 50 L-shell. Finally, selected examples of the model's predictions are presented to illustrate the uses of the tool.

  2. [Robust treatment planning in proton therapy].

    PubMed

    Sterpin, E; Barragan, A; Souris, K; Lee, J A

    2016-10-01

    The concentration of the dose delivered by protons at the end of their path, the Bragg peak, has the potential to improve external radiotherapy treatments. Unfortunately, the main strength of the protons, their finite range, is also their greatest weakness. Any uncertainty on the range may lead to inadequate target coverage or excessive toxicity. The uncertainties have multiple origins and include, among others, ballistic errors, morphological modifications or inaccurate estimations of the physical quantities necessary to predict the proton range. Uncertainties have been part of daily practice in conventional radiotherapy with X-rays for a long time. However, dose distributions delivered with X-rays are much less sensitive to uncertainties than the ones delivered with protons. This relative insensitivity enabled the management of uncertainties through safety margins using a simple formalism. The conditions of validity of this formalism are much more restrictive for proton therapy, leading to the need of developing new tools and adapted strategies to manage accurately these uncertainties. The objective of this paper is to present a vision for the management of uncertainties in proton therapy in the continuity of formalisms established for X-rays. The latter are first summarized before discussing the necessary developments in order to consistently apply them to protons. PMID:27614528

  3. Proton-Coupled Electron Transfer Reactions with Photometric Bases Reveal Free Energy Relationships for Proton Transfer.

    PubMed

    Eisenhart, Thomas T; Howland, William C; Dempsey, Jillian L

    2016-08-18

    The proton-coupled electron transfer (PCET) oxidation of p-aminophenol in acetonitrile was initiated via stopped-flow rapid-mixing and spectroscopically monitored. For oxidation by ferrocenium in the presence of 7-(dimethylamino)quinoline proton acceptors, both the electron transfer and proton transfer components could be optically monitored in the visible region; the decay of the ferrocenium absorbance is readily monitored (λmax = 620 nm), and the absorbance of the 2,4-substituted 7-(dimethylamino)quinoline derivatives (λmax = 370-392 nm) red-shifts substantially (ca. 70 nm) upon protonation. Spectral analysis revealed the reaction proceeds via a stepwise electron transfer-proton transfer process, and modeling of the kinetics traces monitoring the ferrocenium and quinolinium signals provided rate constants for elementary proton and electron transfer steps. As the pKa values of the conjugate acids of the 2,4-R-7-(dimethylamino)quinoline derivatives employed were readily tuned by varying the substituents at the 2- and 4-positions of the quinoline backbone, the driving force for proton transfer was systematically varied. Proton transfer rate constants (kPT,2 = (1.5-7.5) × 10(8) M(-1) s(-1), kPT,4 = (0.55-3.0) × 10(7) M(-1) s(-1)) were found to correlate with the pKa of the conjugate acid of the proton acceptor, in agreement with anticipated free energy relationships for proton transfer processes in PCET reactions. PMID:27500804

  4. Proton-Coupled Electron Transfer Reactions with Photometric Bases Reveal Free Energy Relationships for Proton Transfer.

    PubMed

    Eisenhart, Thomas T; Howland, William C; Dempsey, Jillian L

    2016-08-18

    The proton-coupled electron transfer (PCET) oxidation of p-aminophenol in acetonitrile was initiated via stopped-flow rapid-mixing and spectroscopically monitored. For oxidation by ferrocenium in the presence of 7-(dimethylamino)quinoline proton acceptors, both the electron transfer and proton transfer components could be optically monitored in the visible region; the decay of the ferrocenium absorbance is readily monitored (λmax = 620 nm), and the absorbance of the 2,4-substituted 7-(dimethylamino)quinoline derivatives (λmax = 370-392 nm) red-shifts substantially (ca. 70 nm) upon protonation. Spectral analysis revealed the reaction proceeds via a stepwise electron transfer-proton transfer process, and modeling of the kinetics traces monitoring the ferrocenium and quinolinium signals provided rate constants for elementary proton and electron transfer steps. As the pKa values of the conjugate acids of the 2,4-R-7-(dimethylamino)quinoline derivatives employed were readily tuned by varying the substituents at the 2- and 4-positions of the quinoline backbone, the driving force for proton transfer was systematically varied. Proton transfer rate constants (kPT,2 = (1.5-7.5) × 10(8) M(-1) s(-1), kPT,4 = (0.55-3.0) × 10(7) M(-1) s(-1)) were found to correlate with the pKa of the conjugate acid of the proton acceptor, in agreement with anticipated free energy relationships for proton transfer processes in PCET reactions.

  5. -delayed proton emission branches in 43Cr

    SciTech Connect

    Pomorski, M.; Miernik, K.; Dominik, W.; Janas, Z.; Pfutzner, M.; Bingham, C. R.; Czyrkowski, H.; Cwiok, Mikolaj; Darby, Iain; Dabrowski, Ryszard; Ginter, T. N.; Grzywacz, Robert Kazimierz; Karny, M.; Korgul, A.; Kusmierz, W.; Liddick, Sean; Rajabali, M. M.; Rykaczewski, Krzysztof Piotr; Stolz, A.

    2011-01-01

    The + decay of very neutron-deficient 43Cr was studied by means of an imaging time projection chamber that allowed recording tracks of charged particles. Events of -delayed emission of one, two, and three protons were clearly identified. The absolute branching ratios for these channels were determined to be (81 4)%, (7.1 0.4)%, and (0.08 0.03)%, respectively. 43Cr is thus established as the second case in which the -3p decay occurs. Although the feeding to the proton-bound states in 43V is expected to be negligible, the large branching ratio of (12 4)% for decays without proton emission is found.

  6. Some Perspectives on Future Proton Radioactivity Experiments

    SciTech Connect

    Page, R. D.

    2011-11-30

    Understanding the phenomenon of one-proton emission is crucial for addressing the question of the location of the limits of observable nuclei. Much of the current understanding of this radioactive decay process has been developed and refined through measurements of proton emitters above Z = 50, where {approx}30 proton-emitting nuclei have already been discovered and studied. However, despite the great experimental and theoretical efforts over recent years, some important questions remain unanswered. Possibilities for future experiments to tackle some of these issues are considered.

  7. Polarized proton acceleration program at the AGS

    SciTech Connect

    Lee, Y.Y.

    1981-01-01

    The unexpected importance of high energy spin effects and the success of the ZGS in correcting many intrinsic and imperfection depolarizing resonances led us to attempt to accelerate polarized protons in the AGS. A multi-university/laboratory collaborative effort involving Argonne, Brookhaven, Michigan, Rice and Yale is underway to improve and modify to accelerate polarized protons. From the experience at the ZGS and careful studies made us confident of the feasibility of achieving a polarization of over 60 percent up to 26 GeV/c with an intensity of 10/sup 11/ approx. 10/sup 12/ per pulse. The first polarized proton acceleration at the AGS is expected in 1983.

  8. New developments in proton radiography at LANSCE

    NASA Astrophysics Data System (ADS)

    Morris, Christopher; Proton Radiography Team

    2014-09-01

    In a new application of nuclear physics, a facility for using proton for flash radiography has been developed at the Los Alamos Neutron Science Center (LANSCE). Protons have proven far superior to high energy x-rays for flash radiography. Although this facility is primarily used for studying very fast phenomena such as high explosive driven experiments, it is finding increasing application to other fields, such as tomography of static objects, phase changes in materials, and the dynamics of chemical reactions. The advantages of protons will be discussed and data from some of the recent experiments will be presented.

  9. Proton Radiography: Its uses and Resolution Scaling

    SciTech Connect

    Mariam, Fesseha G.

    2012-08-09

    Los Alamos National Laboratory has used high energy protons as a probe in flash radiography for over a decade. In this time the proton radiography project has used 800 MeV protons, provided by the LANSCE accelerator facility at LANL, to diagnose over five-hundred dynamic experiments in support of stockpile stewardship programs as well as basic materials science. Through this effort significant experience has been gained in using charged particles as direct radiographic probes to diagnose transient systems. The results of this experience will be discussed through the presentation of data from experiments recently performed at the LANL pRad.

  10. Space Environments and Effects: Trapped Proton Model

    NASA Technical Reports Server (NTRS)

    Huston, S. L.; Kauffman, W. (Technical Monitor)

    2002-01-01

    An improved model of the Earth's trapped proton environment has been developed. This model, designated Trapped Proton Model version 1 (TPM-1), determines the omnidirectional flux of protons with energy between 1 and 100 MeV throughout near-Earth space. The model also incorporates a true solar cycle dependence. The model consists of several data files and computer software to read them. There are three versions of the mo'del: a FORTRAN-Callable library, a stand-alone model, and a Web-based model.

  11. A generic algorithm for Monte Carlo simulation of proton transport

    NASA Astrophysics Data System (ADS)

    Salvat, Francesc

    2013-12-01

    A mixed (class II) algorithm for Monte Carlo simulation of the transport of protons, and other heavy charged particles, in matter is presented. The emphasis is on the electromagnetic interactions (elastic and inelastic collisions) which are simulated using strategies similar to those employed in the electron-photon code PENELOPE. Elastic collisions are described in terms of numerical differential cross sections (DCSs) in the center-of-mass frame, calculated from the eikonal approximation with the Dirac-Hartree-Fock-Slater atomic potential. The polar scattering angle is sampled by employing an adaptive numerical algorithm which allows control of interpolation errors. The energy transferred to the recoiling target atoms (nuclear stopping) is consistently described by transformation to the laboratory frame. Inelastic collisions are simulated from DCSs based on the plane-wave Born approximation (PWBA), making use of the Sternheimer-Liljequist model of the generalized oscillator strength, with parameters adjusted to reproduce (1) the electronic stopping power read from the input file, and (2) the total cross sections for impact ionization of inner subshells. The latter were calculated from the PWBA including screening and Coulomb corrections. This approach provides quite a realistic description of the energy-loss distribution in single collisions, and of the emission of X-rays induced by proton impact. The simulation algorithm can be readily modified to include nuclear reactions, when the corresponding cross sections and emission probabilities are available, and bremsstrahlung emission.

  12. MO-B-18C-01: Proton Therapy II: Proton Stereotactic Radiotherapy

    SciTech Connect

    Winey, B; Daartz, J

    2014-06-15

    Proton stereotactic radiotherapy shares fundamental principles with general proton therapy physics, specifically range uncertainties and broad beam measurement techniques. Significant differences emerge when treating with smaller field sizes that suffer lateral disequilibrium and when fractions are reduced. This session will explore the history and scope of proton stereotactic radiotherapy in clinical practice. Uncertainties and treatment planning methods specific to stereotactic treatments will be discussed. The session will include an overview of the physical properties of small proton fields and resulting needs for accurate measurements and modeling of dose distributions for radiosurgery treatment planning. Learning Objectives: Understand the clinical rationale for proton radiosurgery. Understand the similarities and differences from general proton therapy. Understand the similarities and differences from photon stereotactic radiosurgery. Understand the basic physics and clinical physics methods for measuring and commissioning a radiosurgery program.

  13. The specificity of the [NHN] + hydrogen bonds in protonated naphthalene proton sponges

    NASA Astrophysics Data System (ADS)

    Sobczyk, L.

    2010-05-01

    A short review of data related to the structure and infra-red and 1H NMR spectra of protonated naphthalene proton sponges (DMAN-s) is presented. Protonated DMAN-s are characterized by a very low frequency of ν(NHN) + stretching vibrations, ca. 500 cm -1, with an unusual 1H/ 2H isotope effect opposite to that commonly observed, reaching values above 2. The 2,7 derivatives showing the buttressing effect are analyzed. The shortest bridge was found for the 2,7-di-Si(CH 3) 3 derivative, which is close to the shortest bridge in protonated 1,6-diazabicyclo[4.4.4]tetradecane, for which a single minimum potential for proton motion was reported. However, in protonated DAMN-s a double minimum with a very low barrier (LBHB) is always present.

  14. Mechanism of Proton Transport in Proton Exchange Membranes: Insights from Computer Simulation

    SciTech Connect

    Gregory A. Voth

    2010-11-30

    The solvation and transport of hydrated protons in proton exchange membranes (PEMs) such as NafionTM will be described using a novel multi-state reactive molecular dynamics (MD) approach, combined with large scale MD simulation to help probe various PEM morphological models. The multi-state MD methodology allows for the treatment of explicit (Grotthuss) proton shuttling and charge defect delocalization which, in turn, can strongly influence the properties of the hydrated protons in various aqueous and complex environments. A significant extension of the methodology to treat highly acidic (low pH) environments such as the hydrophilic domains of a PEM will be presented. Recent results for proton solvation and transport in NafionTM will be described which reveal the significant role of Grotthuss shuttling and charge defect delocalization on the excess proton solvation structures and transport properties. The role of PEM hydration level and morphology on these properties will also be described.

  15. A Generalized Weizsacker-Williams Method Applied to Pion Production in Proton-Proton Collisions

    NASA Technical Reports Server (NTRS)

    Ahern, Sean C.; Poyser, William J.; Norbury, John W.; Tripathi, R. K.

    2002-01-01

    A new "Generalized" Weizsacker-Williams method (GWWM) is used to calculate approximate cross sections for relativistic peripheral proton-proton collisions. Instead of a mass less photon mediator, the method allows for the mediator to have mass for short range interactions. This method generalizes the Weizsacker-Williams method (WWM) from Coulomb interactions to GWWM for strong interactions. An elastic proton-proton cross section is calculated using GWWM with experimental data for the elastic p+p interaction, where the mass p+ is now the mediator. The resulting calculated cross sections is compared to existing data for the elastic proton-proton interaction. A good approximate fit is found between the data and the calculation.

  16. Void-Assisted Ion-Paired Proton Transfer at Water-Ionic Liquid Interfaces.

    PubMed

    de Eulate, Eva Alvarez; Silvester, Debbie S; Arrigan, Damien W M

    2015-12-01

    At the water-trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate ([P14,6,6,6][FAP]) ionic liquid interface, the unusual electrochemical transfer behavior of protons (H(+)) and deuterium ions (D(+)) was identified. Alkali metal cations (such as Li(+), Na(+), K(+)) did not undergo this transfer. H(+)/D(+) transfers were assisted by the hydrophobic counter anion of the ionic liquid, [FAP](-), resulting in the formation of a mixed capacitive layer from the filling of the latent voids within the anisotropic ionic liquid structure. This phenomenon could impact areas such as proton-coupled electron transfers, fuel cells, and hydrogen storage where ionic liquids are used as aprotic solvents. PMID:26489692

  17. High and low energy proton radiation damage in p/n InP MOCVD solar cells

    NASA Technical Reports Server (NTRS)

    Rybicki, George; Weinberg, Irving; Scheiman, Dave; Vargas-Aburto, Carlos

    1995-01-01

    InP p(+)nn(+) MOCVD solar cells were irradiated with 0.2 MeV and 10 MeV protons to a fluence of 10(exp 13)/sq cm. The degradation of power output, IV behavior, carrier concentration and defect concentration were observed at intermediate points throughout the irradiations. The 0.2 MeV proton irradiated solar cells suffered much greater and more rapid degradation in power output than those irradiated with 10 meV protons. The efficiency losses were accompanied by larger increases in the recombination currents in the 0.2 MeV proton irradiated solar cells. The low energy proton irradiations also had a larger impact on the series resistance of the solar cells. Despite the radiation induced damage, the carrier concentration in the base of the solar cells showed no reduction after 10 MeV or 0.2 MeV proton irradiations and even increased during irradiation with 0.2 MeV protons. In a DLTS study of the irradiated samples, the minority carrier defects H4 and H5 at E(v) + 0.33 and E(v) + 0.52 eV and the majority carrier defects E7 and E10 at E(c)- 0.39 and E(c)-0.74 eV, were observed. The defect introduction rates for the 0.2 MeV proton irradiations were about 20 times higher than for the 10 MeV proton irradiations. The defect E10, observed here after irradiation, has been shown to act as a donor in irradiated n-type InP and may be responsible for obscuring carrier removal. The results of this study are consistent with the much greater damage produced by low energy protons whose limited range causes them to stop in the active region of the solar cell.

  18. [Proton therapy and particle accelerators].

    PubMed

    Fukumoto, Sadayoshi

    2012-01-01

    Since the high energy accelerator plan was changed from a 40 GeV direct machine to a 12GeV cascade one, a 500 MeV rapid cycling booster synchrotron was installed between the injector linac and the 12 GeV main ring at KEK, National Lab. for High Energy Physics. The booster beams were used not only for injection to the main ring but also for medical use. Their energy was reduced to 250 MeV by a graphite block for clinical trial of cancer therapy. In 1970's, pi(-) or heavy ions were supposed to be promising. Although advantage of protons with Bragg Peak was pointed out earlier, they seemed effective only for eye melanoma at that time. In early 1980's, it was shown that they were effective for deep-seated tumor by Tsukuba University with KEK beams. The first dedicated facility was built at Loma Linda University Medical Center. Its synchrotron was made by Fermi National Accelerator Lab. Since a non-resonant accelerating rf cavity was installed, operation of the synchrotron became much easier. Later, innovation of the cyclotron was achieved. Its weight was reduced from 1,000 ton to 200 ton. Some of the cyclotrons are equipped with superconducting coils.

  19. Proton-conducting cerate ceramics

    SciTech Connect

    Pederson, L.R.; Coffey, G.W.; Bates, J.L.; Weber, W.J.

    1996-08-01

    Single-cell solid oxide fuel cells were constructed using strontium cerate as the electrolyte and their performance tested. Like certain zirconates, hafnates, and tantalates, the cerate perovskites are among a class of solid electrolytes that conduct protons at elevated temperatures. Depending on the temperature and chemical environment, these ceramics also support electronic and oxygen ion currents. A maximum power output of {approx}100 mW per cm{sup 2} electrolyte surface area was obtained at 900{degrees}C using 4% hydrogen as the fuel and air as the oxidant. A series of rare earth/ceria/zirconia were prepared and their electrical properties characterized. Rare earth dopants included ytterbia, yttria, terbia, and europia. Ionic conductivities were highest for rare earth/ceria and rare earth zirconia compositions; a minimum in ionic conductivity for all series were found for equimolar mixtures of ceria and zirconia. Cerium oxysulfide is of interest in fossil energy applications because of its high chemical stability and refractory nature. An alternative synthesis route to preparing cerium oxysulfide powders has been developed using combustion techniques.

  20. Proton and cation transport activity of the M2 proton channel from influenza A virus.

    PubMed

    Leiding, Thom; Wang, Jun; Martinsson, Jonas; DeGrado, William F; Arsköld, Sindra Peterson

    2010-08-31

    The M2 protein is a small, single-span transmembrane (TM) protein from the influenza A virus. This virus enters cells via endosomes; as the endosomes mature and become more acidic M2 facilitates proton transport into the viral interior, thereby disrupting matrix protein/RNA interactions required for infectivity. A mystery has been how protons can accumulate in the viral interior without developing a large electrical potential that impedes further inward proton translocation. Progress in addressing this question has been limited by the availability of robust methods of unidirectional insertion of the protein into virus-like vesicles. Using an optimized procedure for reconstitution, we show that M2 has antiporter-like activity, facilitating K(+) or Na(+) efflux when protons flow down a concentration gradient into the vesicles. Cation efflux is very small except under conditions mimicking those encountered by the endosomally entrapped virus, in which protons are flowing through the channel. This proton/cation exchange function is consistent with the known high proton selectivity of the channel. Thus, M2 acts as a proton uniporter that occasionally allows K(+) to flow to maintain electrical neutrality. Remarkably, as the pH inside M2-containing vesicles (pH(in)) decreases, the proton channel activity of M2 is inhibited, but its cation transport activity is activated. This reciprocal inhibition of proton flux and activation of cation flux with decreasing pH(in) first allows accumulation of protons in the early stages of acidification, then trapping of protons within the virus when low pH(in) is achieved.

  1. Proton energy optimization and reduction for intensity-modulated proton therapy

    PubMed Central

    Cao, Wenhua; Lim, Gino; Liao, Li; Li, Yupeng; Jiang, Shengpeng; Li, Xiaoqiang; Li, Heng; Suzuki, Kazumichi; Zhu, X. Ronald; Gomez, Daniel; Zhang, Xiaodong

    2015-01-01

    Intensity-modulated proton therapy (IMPT) is commonly delivered via the spot-scanning technique. To “scan” the target volume, the proton beam is controlled by varying its energy to penetrate the patient’s body at different depths. Although scanning the proton beamlets or spots with the same energy can be as fast as 10–20 m/s, changing from one proton energy to another requires approximately two additional seconds. The total IMPT delivery time thus depends mainly on the number of proton energies used in a treatment. Current treatment planning systems typically use all proton energies that are required for the proton beam to penetrate in a range from the distal edge to the proximal edge of the target. The optimal selection of proton energies has not been well studied. In this study, we sought to determine the feasibility of optimizing and reducing the number of proton energies in IMPT planning. We proposed an iterative mixed-integer programming optimization method to select a subset of all available proton energies while satisfying dosimetric criteria. We applied our proposed method to six patient datasets: four cases of prostate cancer, one case of lung cancer, and one case of mesothelioma. The numbers of energies were reduced by 14.3%–18.9% for the prostate cancer cases, 11.0% for the lung cancer cases, and 26.5% for the mesothelioma case. The results indicate that the number of proton energies used in conventionally designed IMPT plans can be reduced without degrading dosimetric performance. The IMPT delivery efficiency could be improved by energy layer optimization leading to increased throughput for a busy proton center in which a delivery system with slow energy switch is employed. PMID:25295881

  2. Parameterized spectral distributions for meson production in proton-proton collisions

    NASA Technical Reports Server (NTRS)

    Schneider, John P.; Norbury, John W.; Cucinotta, Francis A.

    1995-01-01

    Accurate semiempirical parameterizations of the energy-differential cross sections for charged pion and kaon production from proton-proton collisions are presented at energies relevant to cosmic rays. The parameterizations, which depend on both the outgoing meson parallel momentum and the incident proton kinetic energy, are able to be reduced to very simple analytical formulas suitable for cosmic ray transport through spacecraft walls, interstellar space, the atmosphere, and meteorites.

  3. Memory device using movement of protons

    DOEpatents

    Warren, William L.; Vanheusden, Karel J. R.; Fleetwood, Daniel M.; Devine, Roderick A. B.; Archer, Leo B.; Brown, George A.; Wallace, Robert M.

    2000-01-01

    An enhancement of an electrically written memory element utilizing the motion of protons within a dielectric layer surrounded by layers on either side to confine the protons within the dielectric layer with electrode means attached to the surrounding layers to change the spatial position of the protons within the dielectric layer. The device is preferably constructed as a silicon-silicon dioxide-silicon layered structure with the protons being introduced to the structure during an anneal in an atmosphere containing hydrogen gas. Device operation is enhanced by concluding this anneal step with a sudden cooling. The device operates at low power, is preferably nonvolatile, is radiation tolerant, and is compatible with convention silicon MOS processing for integration with other microelectronics elements on the same silicon substrate.

  4. Memory device using movement of protons

    DOEpatents

    Warren, William L.; Vanheusden, Karel J. R.; Fleetwood, Daniel M.; Devine, Roderick A. B.

    2000-01-01

    An electrically written memory element utilizing the motion of protons within a dielectric layer surrounded by layers on either side to confine the protons within the dielectric layer with electrode means attached to the surrounding layers to change the spatial position of the protons within the dielectric layer. The device is preferably constructed as a silicon-silicon dioxide-silicon layered structure with the protons being introduced to the structure laterally through the exposed edges of the silicon dioxide layer during a high temperature anneal in an atmosphere containing hydrogen gas. The device operates at low power, is preferably nonvolatile, is radiation tolerant, and is compatible with convention silicon MOS processing for integration with other microelectronic elements on the same silicon substrate. With the addition of an optically active layer, the memory element becomes an electrically written, optically read optical memory element.

  5. Memory device using movement of protons

    DOEpatents

    Warren, W.L.; Vanheusden, K.J.R.; Fleetwood, D.M.; Devine, R.A.B.

    1998-11-03

    An electrically written memory element is disclosed utilizing the motion of protons within a dielectric layer surrounded by layers on either side to confine the protons within the dielectric layer with electrode means attached to the surrounding layers to change the spatial position of the protons within the dielectric layer. The device is preferably constructed as a silicon-silicon dioxide-silicon layered structure with the protons being introduced to the structure laterally through the exposed edges of the silicon dioxide layer during a high temperature anneal in an atmosphere containing hydrogen gas. The device operates at low power, is preferably nonvolatile, is radiation tolerant, and is compatible with convention silicon MOS processing for integration with other microelectronic elements on the same silicon substrate. With the addition of an optically active layer, the memory element becomes an electrically written, optically read optical memory element. 19 figs.

  6. Memory device using movement of protons

    DOEpatents

    Warren, William L.; Vanheusden, Karel J. R.; Fleetwood, Daniel M.; Devine, Roderick A. B.

    1998-01-01

    An electrically written memory element utilizing the motion of protons within a dielectric layer surrounded by layers on either side to confine the protons within the dielectric layer with electrode means attached to the surrounding layers to change the spatial position of the protons within the dielectric layer. The device is preferably constructed as a silicon-silicon dioxide-silicon layered structure with the protons being introduced to the structure laterally through the exposed edges of the silicon dioxide layer during a high temperature anneal in an atmosphere containing hydrogen gas. The device operates at low power, is preferably nonvolatile, is radiation tolerant, and is compatible with convention silicon MOS processing for integration with other microelectronic elements on the same silicon substrate. With the addition of an optically active layer, the memory element becomes an electrically written, optically read optical memory element.

  7. Proton acceleration in neutron star magnetospheres

    NASA Technical Reports Server (NTRS)

    Smith, I. A.; Katz, J. I.; Diamond, P. H.

    1992-01-01

    To explain the emission of TeV and PeV gamma rays from accreting X-ray binary sources, protons must be accelerated to several times the gamma-ray energy. It is shown here that at certain times, the plasma in the accretion column of the neutron star may form a deep enough pool that the top portion becomes unstable to convective motions in spite of the strong magnetic field. The resulting turbulence produces fluctuations in the strength of the magnetic field that travel up the accretion column, taking energy out to the region of the energetic protons. The protons resonantly absorb this energy and are accelerated to high energies. Including the synchrotron radiation losses of the protons, it is shown that they can be accelerated to energies that are high enough to explain the gamma-ray observations.

  8. Radiotherapy With Protons And Ion Beams

    SciTech Connect

    Jaekel, Oliver

    2010-04-26

    The use of proton and ion beams has been proposed more than 60 years ago in 1946 by Robert Wilson. In 1955 the first patients were treated with proton beams in Berkeley. Since then radiotherapy with proton and ion beams has constantly been developed at research centers. Within the last decade, however, a considerable number of hospital based facilities came into operation. In this paper an overview over the basic physical and biological properties of proton and ion beams is given. The basic accelerator concepts are outlined and the design of treatment facilities is described. Then the medical physics aspects of the beam delivery, dosimetry and treatment planning are discussed before the clinical concepts are briefly reviewed.

  9. Radiotherapy With Protons And Ion Beams

    NASA Astrophysics Data System (ADS)

    Jäkel, Oliver

    2010-04-01

    The use of proton and ion beams has been proposed more than 60 years ago in 1946 by Robert Wilson. In 1955 the first patients were treated with proton beams in Berkeley. Since then radiotherapy with proton and ion beams has constantly been developed at research centers. Within the last decade, however, a considerable number of hospital based facilities came into operation. In this paper an overview over the basic physical and biological properties of proton and ion beams is given. The basic accelerator concepts are outlined and the design of treatment facilities is described. Then the medical physics aspects of the beam delivery, dosimetry and treatment planning are discussed before the clinical concepts are briefly reviewed.

  10. The Source of Protons at Io

    NASA Astrophysics Data System (ADS)

    Eviatar, A.; Vasyliūnas, V. M.; Johnson, R. E.

    2002-12-01

    The ionosphere of Io is known to be dominated by the molecule ion of sulfur dioxide and the surface and atmosphere are nearly devoid of hydrogen bearing molecules. It is noteworthy, therefore, that electromagnetic waves have been observed near the second and fourth harmonics of the proton gyrofrequency, which is indicative of the presence of a population of pickup protons. We investigate the possible sources of indigenous hydrogen atoms and protons in the exosphere of Io and conclude that charge exchange between incident torus oxygen ions and a population of bound iogenic hydrogen atoms is the only mechanism that can suffice to provide the needed pickup proton source strength and number density. We evaluate various possible sources for such a population.

  11. Design of a Gated Molecular Proton Channel

    SciTech Connect

    Gu, Wei; Zhou, Bo; Geyer, Tihamer; Hutter, Michael C.; Fang, Haiping; Helms, Volkhard H.

    2011-01-17

    The generation of an electrochemical pH gradient across biological membranes using energy from photosynthesis and respiration provides the universal driving force in cells for the production of adenosine triphosphate (ATP), the energy unit of life. Creating such an electrochemical potential requires the transportation of protons against a thermodynamic gradient. In biological proton pumps, chemical energy is used to induce protein conformational changes during each catalytic cycle where one or a few protons are pumped against a proton concentration gradient across the membrane. On the other hand, membrane channels also exist that mediate continuous particle exchange and may be switched between open and closed states. Being able to design nanochannels with similar functions would be of great importance for creating novel molecular devices with a wide range of applications such as molecular motors, fuel cells, rechargeable nanobatteries that provide energy to other nanomachines, and the generation of locally and temporally controlled pH jumps on microfluidic chips.

  12. Suprathermal protons in the interplanetary solar wind

    NASA Technical Reports Server (NTRS)

    Goodrich, C. C.; Lazarus, A. J.

    1976-01-01

    Using the Mariner 5 solar wind plasma and magnetic field data, we present observations of field-aligned suprathermal proton velocity distributions having pronounced high-energy shoulders. These observations, similar to the interpenetrating stream observations of Feldman et al. (1974), are clear evidence that such proton distributions are interplanetary rather than bow shock associated phenomena. Large Alfven speed is found to be a requirement for the occurrence of suprathermal proton distribution; further, we find the proportion of particles in the shoulder to be limited by the magnitude of the Alfven speed. It is suggested that this last result could indicate that the proton thermal anisotropy is limited at times by wave-particle interactions

  13. Resolving electrons from protons in ATIC

    NASA Astrophysics Data System (ADS)

    Chang, J.; Atic Team

    The Advanced Thin Ionization Calorimeter ATIC experiment is designed for high energy cosmic ray ion detection The possibility to identify high energy primary cosmic ray electrons in the presence of the background of cosmic ray protons has been studied by simulating nuclear-electromagnetic cascade showers using the FLUKA Monte Carlo simulation code The ATIC design consisting of a graphite target and an energy detection device a totally active calorimeter built up of 2 5 cm x 2 5 cm x 25 0 cm BGO scintillator bars gives sufficient information to distinguish electrons from protons While identifying about 80 of electrons as such only about 2 in 10 000 protons 150 GeV will mimic electrons In September of 1999 ATIC was exposed to high-energy electron and proton beams at the CERN H2 beam line and this data confirmed the electron detection capabilities of ATIC

  14. Proton Pathways in Green Fluorescence Protein

    PubMed Central

    Agmon, Noam

    2005-01-01

    Proton pathways in green fluorescent protein (GFP) are more extended than previously reported. In the x-ray data of wild-type GFP, a two-step exit pathway exists from the active site to the protein surface, controlled by a threonine switch. A proton entry pathway begins at a glutamate-lysine cluster around Glu-5, and extends all the way to the buried Glu-222 near the active site. This structural evidence suggests that GFP may function as a portable light-driven proton-pump, with proton emitted in the excited state through the switchable exit pathway, and replenished from Glu-222 and the Glu-5 entry pathway in the ground state. PMID:15681647

  15. Physics at a new Fermilab proton driver

    SciTech Connect

    Geer, Steve; /Fermilab

    2006-04-01

    In 2004, motivated by the recent exciting developments in neutrino physics, the Fermilab Long Range Planning Committee identified a new high intensity Proton Driver as an attractive option for the future. At the end of 2004 the APS ''Study on the Physics of Neutrinos'' concluded that the future US neutrino program should have, as one of its components, ''A proton driver in the megawatt class or above and neutrino superbeam with an appropriate very large detector capable of observing Cp violation and measuring the neutrino mass-squared differences and mixing parameters with high precision''. The presently proposed Fermilab Proton Driver is designed to accomplish these goals, and is based on, and would help develop, Linear Collider technology. In this paper the Proton Driver parameters are summarized, and the potential physics program is described.

  16. Measuring the proton selectivity of graphene membranes

    SciTech Connect

    Walker, Michael I.; Keyser, Ulrich F.; Braeuninger-Weimer, Philipp; Weatherup, Robert S.; Hofmann, Stephan

    2015-11-23

    By systematically studying the proton selectivity of free-standing graphene membranes in aqueous solutions, we demonstrate that protons are transported by passing through defects. We study the current-voltage characteristics of single-layer graphene grown by chemical vapour deposition (CVD) when a concentration gradient of HCl exists across it. Our measurements can unambiguously determine that H{sup +} ions are responsible for the selective part of the ionic current. By comparing the observed reversal potentials with positive and negative controls, we demonstrate that the as-grown graphene is only weakly selective for protons. We use atomic layer deposition to block most of the defects in our CVD graphene. Our results show that a reduction in defect size decreases the ionic current but increases proton selectivity.

  17. Polarized proton beams since the ZGS

    SciTech Connect

    Krisch, A.D.

    1994-12-31

    The author discusses research involving polarized proton beams since the ZGS`s demise. He begins by reminding the attendee that in 1973 the ZGS accelerated the world`s first high energy polarized proton beam; all in attendance at this meeting can be proud of this accomplishment. A few ZGS polarized proton beam experiments were done in the early 1970`s; then from about 1976 until 1 October 1979, the majority of the ZGS running time was polarized running. A great deal of fundamental physics was done with the polarized beam when the ZGS ran as a dedicated polarized proton beam from about Fall 1977 until it shut down on 1 October 1979. The newly created polarization enthusiats then dispersed; some spread polarized seeds al over the world by polarizing beams elsewhere; some wound up running the High Energy and SSC programs at DOE.

  18. Hydrogen Bonds in Excited State Proton Transfer

    NASA Astrophysics Data System (ADS)

    Horke, D. A.; Watts, H. M.; Smith, A. D.; Jager, E.; Springate, E.; Alexander, O.; Cacho, C.; Chapman, R. T.; Minns, R. S.

    2016-10-01

    Hydrogen bonding interactions between biological chromophores and their surrounding protein and solvent environment significantly affect the photochemical pathways of the chromophore and its biological function. A common first step in the dynamics of these systems is excited state proton transfer between the noncovalently bound molecules, which stabilizes the system against dissociation and principally alters relaxation pathways. Despite such fundamental importance, studying excited state proton transfer across a hydrogen bond has proven difficult, leaving uncertainties about the mechanism. Through time-resolved photoelectron imaging measurements, we demonstrate how the addition of a single hydrogen bond and the opening of an excited state proton transfer channel dramatically changes the outcome of a photochemical reaction, from rapid dissociation in the isolated chromophore to efficient stabilization and ground state recovery in the hydrogen bonded case, and uncover the mechanism of excited state proton transfer at a hydrogen bond, which follows sequential hydrogen and charge transfer processes.

  19. Development of proton CT imaging system for evaluation of proton range calculation accuracy

    NASA Astrophysics Data System (ADS)

    Tanaka, Sodai; Nishio, Teiji; Matsushita, Keiichiro; Tsuneda, Masato; Aono, Yuki; Kabuki, Shigeto; Sugiura, Akinori; Uesaka, Mitsuru

    2014-09-01

    [Purpose] In treatment planning of proton therapy, X-ray CT image is generally utilized for proton dose and range calculations in a patient body. However, there is an error of the conversion from CT value to WEL (Water Equivalent Length), and it turns into the error of proton range calculation. Therefore, WEL can be directly derived by use of pixel value on proton CT (pCT) image. The purpose of this study is development of a simple and convenient pCT imaging system for evaluation of proton range calculation accuracy. [Method] PCT imaging system was constructed with a plastic scintillator and a cooled CCD camera, which acquires the image of integrated value of the scintillation light toward the beam direction. Experiment for evaluation of this system with 70-MeV protons provided by NIRS cyclotron was performed. The proton beam was irradiated to objects of water and other substances phantom with complicated shape. The pCT image reconstructed from the experimental data was quantitatively evaluated. [Result] Construction of pCT image of various objects was successful. The value of WEL factor of water was 1.0 +/-0.1. [Conclusion] The simple and convenient pCT imaging system for evaluation of proton range calculation accuracy was developed and was evaluated by experiment using proton beam.

  20. Evaluation of the Proton Charge Radius from Electron–Proton Scattering

    SciTech Connect

    Arrington, John; Sick, Ingo

    2015-09-15

    In light of the proton radius puzzle, the discrepancy between measurements of the proton charge radius from muonic hydrogen and those from electronic hydrogen and electron–proton (e–p) scattering measurements, we re-examine the charge radius extractions from electron scattering measurements. We provide a recommended value for the proton root-mean-square charge radius, r{sub E} = 0.879 ± 0.011 fm, based on a global examination of elastic e–p scattering data. The uncertainties include contributions to account for tension between different data sets and inconsistencies between radii using different extraction procedures.

  1. Electron/proton spectrometer certification documentation analyses

    NASA Technical Reports Server (NTRS)

    Gleeson, P.

    1972-01-01

    A compilation of analyses generated during the development of the electron-proton spectrometer for the Skylab program is presented. The data documents the analyses required by the electron-proton spectrometer verification plan. The verification plan was generated to satisfy the ancillary hardware requirements of the Apollo Applications program. The certification of the spectrometer requires that various tests, inspections, and analyses be documented, approved, and accepted by reliability and quality control personnel of the spectrometer development program.

  2. The Francis H. Burr Proton Therapy Center

    NASA Astrophysics Data System (ADS)

    Flanz, Jay; Kooy, Hanne; DeLaney, Thomas F.

    The Francis H. Burr Proton Therapy Center (FHBPTC) is one of the first hospital-based proton therapy (PT) facilities. Its development was the natural evolution of several decades of PT experience of the Massachusetts General Hospital treating patients at the Harvard Cyclotron Laboratory. The operations of the FHBPTC reflect the combined missions of patient care, clinical and physics research, technological developments, and education. This chapter will discuss aspects of the history, evolution, and performance of this unique PT center.

  3. Patient positioning in the proton radiotherapy era.

    PubMed

    Devicienti, Salvatore; Strigari, Lidia; D'Andrea, Marco; Benassi, Marcello; Dimiccoli, Vincenzo; Portaluri, Maurizio

    2010-05-13

    The main hindrance to the diffusion of proton therapy facilities is the high cost for gantry installations. An alternative technical option is provided by fixed-beam treatment rooms, where the patient is rotated and translated in space with a robotic arm solution to enable beam incidence from various angles. The technological efforts based on robotic applications made up to now for patient positioning in proton beam facilities are described here, highlighting their limitations and perspectives.

  4. Proton conducting membrane using a solid acid

    NASA Technical Reports Server (NTRS)

    Haile, Sossina M. (Inventor); Chisholm, Calum (Inventor); Boysen, Dane A. (Inventor); Narayanan, Sekharipuram R. (Inventor)

    2006-01-01

    A solid acid material is used as a proton conducting membrane in an electrochemical device. The solid acid material can be one of a plurality of different kinds of materials. A binder can be added, and that binder can be either a nonconducting or a conducting binder. Nonconducting binders can be, for example, a polymer or a glass. A conducting binder enables the device to be both proton conducting and electron conducting.

  5. Periods of High Intensity Solar Proton Flux

    NASA Technical Reports Server (NTRS)

    Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adams, James H.; Dietrich, William F.

    2012-01-01

    Analysis is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.

  6. Patient positioning in the proton radiotherapy era

    PubMed Central

    2010-01-01

    The main hindrance to the diffusion of proton therapy facilities is the high cost for gantry installations. An alternative technical option is provided by fixed-beam treatment rooms, where the patient is rotated and translated in space with a robotic arm solution to enable beam incidence from various angles. The technological efforts based on robotic applications made up to now for patient positioning in proton beam facilities are described here, highlighting their limitations and perspectives. PMID:20465816

  7. IFSERF, an isotope-filtered SERF experiment for the precise measurement of proton-proton coupling constants between chemically equivalent protons.

    PubMed

    Nolis, Pau; Roglans, Anna; Parella, Teodor

    2005-04-01

    An isotope-filtered selective refocusing (IFSERF) experiment is presented for the sensitive and precise measurement of the proton-proton coupling constant between chemically equivalent protons. The 2D NMR method combines an initial doubly selective isotope filter based on heteronuclear cross-polarization followed by a selective J-resolved block. The coupling topologies obtained from several 2D variants of the IFSERF experiment are described for the simultaneous measurement of both proton-proton and proton-carbon coupling constants in the involved AA'XX' spin system. Application on the determination of the relative configuration of double bonds in symmetrical molecules is illustrated.

  8. Proton microscopy at GSI and FAIR

    SciTech Connect

    Merrill, Frank E; Mariam, Fesseha G; Golubev, A A; Turtikov, V I; Varentsov, D

    2009-01-01

    Proton radiography was invented in the 1990's at Los Alamos National Laboratory (LANL) as a diagnostic to study dynamic material properties under extreme pressures, strain and strain rate. Since this time hundreds of dynamic proton radiography experiments have been performed at LANL and facilities have been commissioned at the Institute for Theoretical and Experimental Physics (ITEP) in Russia for similar applications in dynamic material studies. Recently an international collaboration was formed to develop a new proton radiography capability for the study of dynamic material properties at the Facility for Anti-proton and Ion Research (FAIR) located at Gesellschaft fuer Schwerionenforschung (GSI) in Darmstadt, Germany. This new Proton microscope for FAIR (PRIOR) will provide radiographic imaging of dynamic systems with unprecedented spatial, temporal and density resolution, resulting in a window for understanding dynamic material properties at new length scales. These dynamic experiments will be driven with many energy sources including heavy ions, high explosives and lasers. The design of the proton microscope and expected radiographic performance is presented.

  9. Proton conductivity in ampullae of Lorenzini jelly.

    PubMed

    Josberger, Erik E; Hassanzadeh, Pegah; Deng, Yingxin; Sohn, Joel; Rego, Michael J; Amemiya, Chris T; Rolandi, Marco

    2016-05-01

    In 1678, Stefano Lorenzini first described a network of organs of unknown function in the torpedo ray-the ampullae of Lorenzini (AoL). An individual ampulla consists of a pore on the skin that is open to the environment, a canal containing a jelly and leading to an alveolus with a series of electrosensing cells. The role of the AoL remained a mystery for almost 300 years until research demonstrated that skates, sharks, and rays detect very weak electric fields produced by a potential prey. The AoL jelly likely contributes to this electrosensing function, yet the exact details of this contribution remain unclear. We measure the proton conductivity of the AoL jelly extracted from skates and sharks. The room-temperature proton conductivity of the AoL jelly is very high at 2 ± 1 mS/cm. This conductivity is only 40-fold lower than the current state-of-the-art proton-conducting polymer Nafion, and it is the highest reported for a biological material so far. We suggest that keratan sulfate, identified previously in the AoL jelly and confirmed here, may contribute to the high proton conductivity of the AoL jelly with its sulfate groups-acid groups and proton donors. We hope that the observed high proton conductivity of the AoL jelly may contribute to future studies of the AoL function. PMID:27386543

  10. In vivo proton range verification: a review

    NASA Astrophysics Data System (ADS)

    Knopf, Antje-Christin; Lomax, Antony

    2013-08-01

    Protons are an interesting modality for radiotherapy because of their well defined range and favourable depth dose characteristics. On the other hand, these same characteristics lead to added uncertainties in their delivery. This is particularly the case at the distal end of proton dose distributions, where the dose gradient can be extremely steep. In practice however, this gradient is rarely used to spare critical normal tissues due to such worries about its exact position in the patient. Reasons for this uncertainty are inaccuracies and non-uniqueness of the calibration from CT Hounsfield units to proton stopping powers, imaging artefacts (e.g. due to metal implants) and anatomical changes of the patient during treatment. In order to improve the precision of proton therapy therefore, it would be extremely desirable to verify proton range in vivo, either prior to, during, or after therapy. In this review, we describe and compare state-of-the art in vivo proton range verification methods currently being proposed, developed or clinically implemented.

  11. Proton conductivity in ampullae of Lorenzini jelly

    PubMed Central

    Josberger, Erik E.; Hassanzadeh, Pegah; Deng, Yingxin; Sohn, Joel; Rego, Michael J.; Amemiya, Chris T.; Rolandi, Marco

    2016-01-01

    In 1678, Stefano Lorenzini first described a network of organs of unknown function in the torpedo ray—the ampullae of Lorenzini (AoL). An individual ampulla consists of a pore on the skin that is open to the environment, a canal containing a jelly and leading to an alveolus with a series of electrosensing cells. The role of the AoL remained a mystery for almost 300 years until research demonstrated that skates, sharks, and rays detect very weak electric fields produced by a potential prey. The AoL jelly likely contributes to this electrosensing function, yet the exact details of this contribution remain unclear. We measure the proton conductivity of the AoL jelly extracted from skates and sharks. The room-temperature proton conductivity of the AoL jelly is very high at 2 ± 1 mS/cm. This conductivity is only 40-fold lower than the current state-of-the-art proton-conducting polymer Nafion, and it is the highest reported for a biological material so far. We suggest that keratan sulfate, identified previously in the AoL jelly and confirmed here, may contribute to the high proton conductivity of the AoL jelly with its sulfate groups—acid groups and proton donors. We hope that the observed high proton conductivity of the AoL jelly may contribute to future studies of the AoL function. PMID:27386543

  12. Proton Stopping Power in Warm Dense Hydrogen

    NASA Astrophysics Data System (ADS)

    Higginson, Drew; Chen, Sophia; Atzeni, Stefano; Gauthier, Maxence; Mangia, Feliciana; Marquès, Jean-Raphaël; Riquier, Raphaël; Fuchs, Julien

    2013-10-01

    Warm dense matter (WDM) research is fundamental to many fields of physics including fusion sciences, and astrophysical phenomena. In the WDM regime, particle stopping-power differs significantly from cold matter and ideal plasma due to free electron contributions, plasma correlation effects and electron degeneracy. The creation of WDM with temporal duration consistent with the particles probes is difficult to achieve experimentally. The short-pulse laser platform allows for the production of WDM along with relatively short bunches of protons compatible of such measurements, however, until recently, the intrinsic broadband proton spectrum was not well suited to investigate the stopping power directly. This difficulty has been overcome using a novel magnetic particle selector (ΔE/E = 10%) to select protons (in the range 100-1000 keV) as demonstrated with the ELFIE laser in LULI, France. These protons bunches probe high-density (5 × 1020 cm-3) gases (H, He) heated by a nanosecond laser to reach estimated temperatures above 100 eV. Measurement of the proton energy loss within the heated gas allows the stopping power to be determined quantitatively. The experimental results in cold matter are compared to preexisting models to give credibility to the measurement technique. The results from heated matter show that the stopping power of 450 keV protons is dramatically reduced within heated hydrogen plasma.

  13. Beam Loss Studies for the 2-MW LBNE Proton Beam Line

    SciTech Connect

    Drozhdin, A.I.; Childress, S.R.; Mokhov, N.V.; Tropin, I.S.; Zwaska, R.; /Fermilab

    2012-05-01

    Severe limits are put on allowable beam loss during extraction and transport of a 2.3 MW primary proton beam for the Long Baseline Neutrino Experiment (LBNE) at Fermilab. Detailed simulations with the STRUCT and MARS codes have evaluated the impact of beam loss of 1.6 x 10{sup 14} protons per pulse at 120 GeV, ranging from a single pulse full loss to sustained small fractional loss. It is shown that loss of a single beam pulse at 2.3 MW will result in a catastrophic event: beam pipe destruction, damaged magnets and very high levels of residual radiation inside and outside the tunnel. Acceptable beam loss limits have been determined and robust solutions developed to enable efficient proton beam operation under these constraints.

  14. Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives.

    PubMed

    Martínez-Cifuentes, Maximiliano; Clavijo-Allancan, Graciela; Zuñiga-Hormazabal, Pamela; Aranda, Braulio; Barriga, Andrés; Weiss-López, Boris; Araya-Maturana, Ramiro

    2016-01-01

    A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules. PMID:27399676

  15. Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives

    PubMed Central

    Martínez-Cifuentes, Maximiliano; Clavijo-Allancan, Graciela; Zuñiga-Hormazabal, Pamela; Aranda, Braulio; Barriga, Andrés; Weiss-López, Boris; Araya-Maturana, Ramiro

    2016-01-01

    A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules. PMID:27399676

  16. Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives.

    PubMed

    Martínez-Cifuentes, Maximiliano; Clavijo-Allancan, Graciela; Zuñiga-Hormazabal, Pamela; Aranda, Braulio; Barriga, Andrés; Weiss-López, Boris; Araya-Maturana, Ramiro

    2016-07-05

    A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules.

  17. A study of the first solar proton event of current solar cycle recorded by satellites and ground based detectors

    NASA Astrophysics Data System (ADS)

    Gerontidou, M.; Mavromichalaki, H.; Plainaki, C.; Belov, A.; Eroshenko, E.; Yanke, V.; Laurenza, M.; Storini, M.

    2013-09-01

    On 2012, May 17 the GOES satellites recorded a great and simultaneous increase on proton flux in different energy channels thereby producing a solar proton event (SPE). These protons had enough energy to be recorded by the ground based worldwide network of neutron monitors thereby producing the first ground level enhancement of solar cosmic rays (GLE71) of the current solar cycle. In this work a combined study of the this solar proton event, as it is recorded by GOES satellites as well as by the ground based network of Neutron monitors is presented. On 2012, May 17 at 02:10 UTC the GOES spacecraft recorded a fast rise in the flux of solar protons, followed by a slower decay, which was still ongoing on 18 May 2012. Several solar proton events stronger than that of 17 May 2012 were detected by GOES in January and March 2012. This event of 17 May extended to much higher energies than those earlier ones, but was weaker at lower energies. Through this research an attempt to understand the reason for these differences is performed. Additionally, a first attempt to derive the characteristics of this recent proton event, by applying an updated version of the NMBANGLE PPOLA model, already used for modeling past GLEs (e.g. GLE70 ) is presented. The special characteristics of this event with respect to the result of NMBANGLE POLLA model can provide useful information not only about the solar source that triggered this SPE, but also its special impact at interplanetary space.

  18. Moving protons with pendant amines: proton mobility in a nickel catalyst for oxidation of hydrogen.

    PubMed

    O'Hagan, Molly; Shaw, Wendy J; Raugei, Simone; Chen, Shentan; Yang, Jenny Y; Kilgore, Uriah J; DuBois, Daniel L; Bullock, R Morris

    2011-09-14

    Proton transport is ubiquitous in chemical and biological processes, including the reduction of dioxygen to water, the reduction of CO(2) to formate, and the production/oxidation of hydrogen. In this work we describe intramolecular proton transfer between Ni and positioned pendant amines for the hydrogen oxidation electrocatalyst [Ni(P(Cy)(2)N(Bn)(2)H)(2)](2+) (P(Cy)(2)N(Bn)(2) = 1,5-dibenzyl-3,7-dicyclohexyl-1,5-diaza-3,7-diphosphacyclooctane). Rate constants are determined by variable-temperature one-dimensional NMR techniques and two-dimensional EXSY experiments. Computational studies provide insight into the details of the proton movement and energetics of these complexes. Intramolecular proton exchange processes are observed for two of the three experimentally observable isomers of the doubly protonated Ni(0) complex, [Ni(P(Cy)(2)N(Bn)(2)H)(2)](2+), which have N-H bonds but no Ni-H bonds. For these two isomers, with pendant amines positioned endo to the Ni, the rate constants for proton exchange range from 10(4) to 10(5) s(-1) at 25 °C, depending on isomer and solvent. No exchange is observed for protons on pendant amines positioned exo to the Ni. Analysis of the exchange as a function of temperature provides a barrier for proton exchange of ΔG(‡) = 11-12 kcal/mol for both isomers, with little dependence on solvent. Density functional theory calculations and molecular dynamics simulations support the experimental observations, suggesting metal-mediated intramolecular proton transfers between nitrogen atoms, with chair-to-boat isomerizations as the rate-limiting steps. Because of the fast rate of proton movement, this catalyst may be considered a metal center surrounded by a cloud of exchanging protons. The high intramolecular proton mobility provides information directly pertinent to the ability of pendant amines to accelerate proton transfers during catalysis of hydrogen oxidation. These results may also have broader implications for proton movement in

  19. Moving Protons with Pendant Amines: Proton Mobility in a Nickel Catalyst for Oxidation of Hydrogen

    SciTech Connect

    O'Hagan, Molly; Shaw, Wendy J.; Raugei, Simone; Chen, Shentan; Yang, Jenny Y.; Kilgore, Uriah J.; DuBois, Daniel L.; Bullock, R. Morris

    2011-05-19

    Proton transport is ubiquitous in chemical and biological processes, including the reduction of dioxygen to water, the reduction of CO₂ to formate, and the production/oxidation of hydrogen. In this work we describe intramolecular proton transfer between Ni and positioned pendant amines for the hydrogen oxidation electrocatalyst [Ni(PCy₂NBn₂H)₂]²⁺ (PCy₂NBn₂ = 1,5-dibenzyl-3,7-dicyclohexyl-1,5-diaza-3,7-diphosphacyclooctane). Rate constants are determined by variable-temperature one-dimensional NMR techniques and two-dimensional EXSY experiments. Computational studies provide insight into the details of the proton movement and energetics of these complexes. Intramolecular proton exchange processes are observed for two of the three experimentally observable isomers of the doubly protonated Ni(0) complex, [Ni(PCy₂NBn₂H)₂]²⁺, which have N–H bonds but no Ni–H bonds. For these two isomers, with pendant amines positioned endo to the Ni, the rate constants for proton exchange range from 10⁴ to 10⁵ s⁻¹ at 25 °C, depending on isomer and solvent. No exchange is observed for protons on pendant amines positioned exo to the Ni. Analysis of the exchange as a function of temperature provides a barrier for proton exchange of ΔG = 11–12 kcal/mol for both isomers, with little dependence on solvent. Density functional theory calculations and molecular dynamics simulations support the experimental observations, suggesting metal-mediated intramolecular proton transfers between nitrogen atoms, with chair-to-boat isomerizations as the rate-limiting steps. Because of the fast rate of proton movement, this catalyst may be considered a metal center surrounded by a cloud of exchanging protons. The high intramolecular proton mobility provides information directly pertinent to the ability of pendant amines to accelerate proton transfers during catalysis of hydrogen oxidation

  20. Proton affinity changes driving unidirectional proton transport in the bacteriorhodopsin photocycle.

    PubMed

    Onufriev, Alexey; Smondyrev, Alexander; Bashford, Donald

    2003-10-01

    Bacteriorhodopsin is the smallest autonomous light-driven proton pump. Proposals as to how it achieves the directionality of its trans-membrane proton transport fall into two categories: accessibility-switch models in which proton transfer pathways in different parts of the molecule are opened and closed during the photocycle, and affinity-switch models, which focus on changes in proton affinity of groups along the transport chain during the photocycle. Using newly available structural data, and adapting current methods of protein protonation-state prediction to the non-equilibrium case, we have calculated the relative free energies of protonation microstates of groups on the transport chain during key conformational states of the photocycle. Proton flow is modeled using accessibility limitations that do not change during the photocycle. The results show that changes in affinity (microstate energy) calculable from the structural models are sufficient to drive unidirectional proton transport without invoking an accessibility switch. Modeling studies for the N state relative to late M suggest that small structural re-arrangements in the cytoplasmic side may be enough to produce the crucial affinity change of Asp96 during N that allows it to participate in the reprotonation of the Schiff base from the cytoplasmic side. Methodologically, the work represents a conceptual advance compared to the usual calculations of pK(a) using macroscopic electrostatic models. We operate with collective states of protonation involving all key groups, rather than the individual-group pK(a) values traditionally used. When combined with state-to-state transition rules based on accessibility considerations, a model for non-equilibrium proton flow is obtained. Such methods should also be applicable to other active proton-transport systems. PMID:14499620

  1. Proton clouds to measure long-range contacts between nonexchangeable side chain protons in solid-state NMR.

    PubMed

    Sinnige, Tessa; Daniëls, Mark; Baldus, Marc; Weingarth, Markus

    2014-03-26

    We show that selective labeling of proteins with protonated amino acids embedded in a perdeuterated matrix, dubbed 'proton clouds', provides general access to long-range contacts between nonexchangeable side chain protons in proton-detected solid-state NMR, which is important to study protein tertiary structure. Proton-cloud labeling significantly improves spectral resolution by simultaneously reducing proton line width and spectral crowding despite a high local proton density in clouds. The approach is amenable to almost all canonical amino acids. Our method is demonstrated on ubiquitin and the β-barrel membrane protein BamA.

  2. Atmospheric Influence of the Solar Proton Events and Ground Level Enhancement in January 2005

    NASA Astrophysics Data System (ADS)

    Jackman, C. H.; Funke, B.; Lopez-Puertas, M.; Versik, S.; Stiller, G. P.; Tylka, A. J.; Marsh, D. R.; Vitt, F. M.; Garcia, R. R.; Randall, C. E.; Fleming, E. L.

    2009-12-01

    Solar eruptions in early 2005 led to a substantial barrage of charged particles on the Earth’s atmosphere in a few separate events during the January 16-21 period. Significant production of OH [Verronen et al. 2006] and destruction of ozone [Verronen et al. 2006; Seppala et al. 2006] have been documented due to the enhanced solar proton flux in January 2005. These solar proton events (SPEs) also led to the production of NOx (NO, NO2), when the protons and associated secondary electrons dissociated molecular nitrogen (N2). Our simulations with the Whole Atmosphere Community Climate Model (WACCM) show that mesospheric NOx is enhanced in both the polar Southern (greater than 10 ppbv) and Northern (greater than 40 ppbv) Hemispheres. Envisat MIPAS measurements of nighttime NO2 for the Northern Hemisphere are in reasonable agreement with these predictions. Such enhancements are considerable for the mesosphere and led to increases in Northern Hemisphere polar upper stratospheric odd nitrogen (NOy) greater than 20% in February and March 2005. The largest ground level enhancement (GLE) of solar cycle 23 occurred on January 20, 2005 with a neutron monitor increase of about 270% [Gopalswamy et al. 2005]. Using results from a recent analysis of the proton spectrum derived from neutron-monitor data [Tylka & Dietrich 2009], we found that protons of energies 300 to 20,000 MeV, not normally included in our computations, led to enhanced stratospheric NOy of less than 1% as a result of this GLE. Thus, the primary impact of the January 2005 solar events on the middle atmosphere was through protons with energies less than 300 MeV. This presentation will show both short- and longer-term changes due to the January 2005 solar protons. Gopalswamy, N., et al., Coronal mass ejections and ground level enhancements, 29th International Cosmic Ray Conference Pune, 1, 169-173, 2005. Seppala, A., et al., Destruction of the tertiary ozone maximum during a solar proton event, Geophys. Res. Lett

  3. Dynamical Changes Induced by the Very Large Solar Proton Events in October-November 2003

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; Roble, Raymond G.

    2006-01-01

    The very large solar storms in October-November 2003 caused solar proton events (SPEs) at the Earth and impacted the upper atmospheric polar cap regions. The Thermosphere Ionosphere Mesosphere Electrodynamic General Circulation Mode (TIME-GCM) was used to study the atmospheric dynamical influence of the solar protons that occurred in Oct-Nov 2003, the fourth largest period of SPEs measured in the past 40 years. The highly energetic solar protons caused ionization and changes in the electric field, which led to Joule heating of the mesosphere and lower thermosphere. This heating led to temperature increases up to 4K in the upper mesosphere. The solar proton-induced ionization, as well as dissociation processes, led to the production of odd hydrogen (HO(x)) and odd nitrogen (NO(y)). Substantial (>40%) short-lived ozone decreases followed these enhancements of HO(x) and NO(y) and led to a cooling of the mesosphere and upper stratosphere. This cooling led to temperature decreases up to 2.5K. The solar proton-caused temperature changes led to maximum meridional and zonal wind variations of +/- 2 m/s on background winds up to +/- 30 m/s. The solar proton-induced wind perturbations were computed to taper off over a period of several days past the SPEs. Solar cycle 23 was accompanied by ten very large SPEs between 1998 and 2005, along with numerous smaller events. These solar proton-driven atmospheric variations need to be carefully considered when examining other polar changes.

  4. Double ionization of helium by particle impact

    NASA Technical Reports Server (NTRS)

    Jacobsen, Finn M.

    1990-01-01

    Experimental results are reviewed of the ratio, R sq., of double to single ionization of He by proton, antiproton, electron and positron impact in the energy range from 0.15 to about 10 MeV/amu. At high velocities (greater than 1 to 2 MeV/amu) values of R sq. caused by electron impact merge with those for the proton with the antiproton, electron values being up to a factor of 2 greater than that for the p, positron. At these velocities the single ionization cross sections caused by impact of any of these four particles are indistinguishable.

  5. Range uncertainties in proton therapy and the role of Monte Carlo simulations

    PubMed Central

    Paganetti, Harald

    2012-01-01

    The main advantages of proton therapy are the reduced total energy deposited in the patient as compared to photon techniques and the finite range of the proton beam. The latter adds an additional degree of freedom to treatment planning. The range in tissue is associated with considerable uncertainties caused by imaging, patient setup, beam delivery and dose calculation. Reducing the uncertainties would allow a reduction of the treatment volume and thus allow a better utilization of the advantages of protons. This article summarizes the role of Monte Carlo simulations when aiming at a reduction of range uncertainties in proton therapy. Differences in dose calculation when comparing Monte Carlo with analytical algorithms are analyzed as well as range uncertainties due to material constants and CT conversion. Range uncertainties due to biological effects and the role of Monte Carlo for in vivo range verification are discussed. Furthermore, the current range uncertainty recipes used at several proton therapy facilities are revisited. We conclude that a significant impact of Monte Carlo dose calculation can be expected in complex geometries where local range uncertainties due to multiple Coulomb scattering will reduce the accuracy of analytical algorithms. In these cases Monte Carlo techniques might reduce the range uncertainty by several mm. PMID:22571913

  6. A functional [NiFe]-hydrogenase model compound that undergoes biologically relevant reversible thiolate protonation.

    PubMed

    Weber, Katharina; Krämer, Tobias; Shafaat, Hannah S; Weyhermüller, Thomas; Bill, Eckhard; van Gastel, Maurice; Neese, Frank; Lubitz, Wolfgang

    2012-12-26

    Two model compounds of the active site of [NiFe]-hydrogenases with an unusual {S(2)Ni(μ-S)(μ-CO)Fe(CO)(2)S}-coordination environment around the metals are reported. The neutral compound [Ni(xbsms)(μ-CO)(μ-S)Fe(CO)(2)('S')], (1) (H(2)xbsms = 1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene) is converted to [1H][BF(4)] by reversible protonation using HBF(4)·Et(2)O. The protonation takes place at the terminal thiolate sulfur atom that is coordinated to nickel. Catalytic intermediates with a protonated terminal cysteinate were suggested for the native protein but have not yet been confirmed experimentally. [1H][BF(4)] is the first dinuclear [NiFe] model compound for such a species. Both complexes have been synthesized and characterized by X-ray crystallography, NMR-, FTIR-, and (57)Fe-Mössbauer spectroscopy as well as by electronic absorption and resonance Raman spectroscopy. The experimental results clearly show that the protonation has a significant impact on the electronic structure of the iron center, although it takes place at the nickel site. DFT calculations support the interpretation of the spectroscopic data and indicate the presence of a bonding interaction between the metal ions, which is relevant for the enzyme as well. Electrochemical experiments show that both 1 and [1H][BF(4)] are active for electrocatalytic proton reduction in aprotic solvents.

  7. A functional [NiFe]-hydrogenase model compound that undergoes biologically relevant reversible thiolate protonation.

    PubMed

    Weber, Katharina; Krämer, Tobias; Shafaat, Hannah S; Weyhermüller, Thomas; Bill, Eckhard; van Gastel, Maurice; Neese, Frank; Lubitz, Wolfgang

    2012-12-26

    Two model compounds of the active site of [NiFe]-hydrogenases with an unusual {S(2)Ni(μ-S)(μ-CO)Fe(CO)(2)S}-coordination environment around the metals are reported. The neutral compound [Ni(xbsms)(μ-CO)(μ-S)Fe(CO)(2)('S')], (1) (H(2)xbsms = 1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene) is converted to [1H][BF(4)] by reversible protonation using HBF(4)·Et(2)O. The protonation takes place at the terminal thiolate sulfur atom that is coordinated to nickel. Catalytic intermediates with a protonated terminal cysteinate were suggested for the native protein but have not yet been confirmed experimentally. [1H][BF(4)] is the first dinuclear [NiFe] model compound for such a species. Both complexes have been synthesized and characterized by X-ray crystallography, NMR-, FTIR-, and (57)Fe-Mössbauer spectroscopy as well as by electronic absorption and resonance Raman spectroscopy. The experimental results clearly show that the protonation has a significant impact on the electronic structure of the iron center, although it takes place at the nickel site. DFT calculations support the interpretation of the spectroscopic data and indicate the presence of a bonding interaction between the metal ions, which is relevant for the enzyme as well. Electrochemical experiments show that both 1 and [1H][BF(4)] are active for electrocatalytic proton reduction in aprotic solvents. PMID:23194246

  8. Singlet pairing gaps of neutrons and protons in hyperonic neutron stars

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Liu, Cheng-Zhi; Fan, Cun-Bo; Han, Xing-Wei; Zhang, Xiao-Jun; Zhu, Ming-Feng; Wang, Hong-Yan; Liu, Guang-Zhou

    2015-05-01

    The 1S0 nucleonic superfluids are investigated within the relativistic mean-field model and Bardeen-Cooper-Schrieffer theory in hyperonic neutron stars. The 1S0 pairing gaps of neutrons and protons are calculated based on the Reid soft-core interaction as the nucleon-nucleon interaction. In particular, we have studied the influence of degrees of freedom for hyperons on the 1S0 nucleonic pairing gap in neutron star matter. It is found that the appearance of hyperons has little impact on the baryonic density range and the size of the 1S0 neutronic pairing gap; the 1S0 protonic pairing gap also decreases slightly in this region where ρB = 0.0-0.393 fm-3. However, if baryonic density becomes greater than 0.393 fm-3, the 1S0 protonic pairing gap obviously increases. In addition, the possible range for a protonic superfluid is obviously enlarged due to the presence of hyperons. In our results, the hyperons change the 1S0 protonic pairing gap, which must change the cooling properties of neutron stars. Supported by the National Natural Science Foundation of China.

  9. Computation of doses for large-angle Coulomb scattering of proton pencil beams.

    PubMed

    Ciangaru, George; Sahoo, Narayan; Zhu, X Ronald; Sawakuchi, Gabriel O; Gillin, Michael T

    2009-12-21

    In this work we present a study of the impact of considering higher order terms in Molière's multiple Coulomb scattering (MCS) theory for the purpose of calculating scanning proton pencil beam lateral dose profiles in water. The proton beam profile in air, just before entering the target medium, was modeled with a sum of Gaussians fitted with measured data. The subsequent proton scattering in water was described using the three-term Molière distribution, which covers both small- and large-angle scatterings. We compared measured and computed lateral dose profiles at the 2 cm and at the near-Bragg peak depths for proton pencil beams with energies of 72.5 MeV, 121.2 MeV, 163.9 MeV and 221.8 MeV. At shallow depths, the Coulomb interaction model provided a good description of the profiles for all energies, except for 221.8 MeV. At the near-Bragg peak depths, the Coulomb interaction model provided a good description of the profiles only for the 72.5 MeV. The observed discrepancies may be attributed to the additional contributions from nuclear interactions, which may be quantified only after an accurate description of the MCS. The analysis presented in this work did not require user-adjustable parameters and may be carried out in a similar way for any other media, depths and proton energies.

  10. Effect of the Rayleigh-Taylor-instability on radiation-pressure-accelerated protons from solid-density hydrogen jets

    NASA Astrophysics Data System (ADS)

    Goede, Sebastian; Roedel, Christian; Gauthier, Maxence; Schumaker, Will; MacDonald, Michael; Kim, Jongjin; Mishra, Rohini; Fiuza, Frederico; Glenzer, Siegfried; Zeil, Karl; Schlenvoigt, Hans-Peter; Obst, Lieselotte; Metzkes, Josefine; Brack, Florian; Gebhardt, Rene; Rehwald, Martin; Sommer, Philipp; Bock, Stefan; Helbig, Uwe; Cowan, Tom; Schramm, Ulrich

    2015-11-01

    Proton beams generated by relativistic laser-plasma interactions are of great interest in warm dense matter research due to applications such as isochoric heating and stopping power measurements. Radiation pressure acceleration (RPA) from pure hydrogen targets is a promising approach towards developing low emittance beams with high particle flux, one of the key requirements for above studies. We developed a novel target utilizing cryogenic hydrogen jets at solid densities for ion acceleration experiments. Using the 150 TW laser system DRACO at HZDR we measured pure proton spectra exceeding 10 MeV for peak intensities of 5 x1020 W/cm2 at a repetition rate of 1 Hz. The proton beam shows a net-like structure. The experimental results will be discussed with the support of particle-in-cell simulations to assess the impact of the Rayleigh-Taylor-instability on radiation-pressure-accelerated protons

  11. Protons sensitize epithelial cells to mesenchymal transition.

    PubMed

    Wang, Minli; Hada, Megumi; Saha, Janapriya; Sridharan, Deepa M; Pluth, Janice M; Cucinotta, Francis A

    2012-01-01

    Proton radiotherapy has gained more favor among oncologists as a treatment option for localized and deep-seated tumors. In addition, protons are a major constituent of the space radiation astronauts receive during space flights. The potential for these exposures to lead to, or enhance cancer risk has not been well studied. Our objective is to study the biological effects of low energy protons on epithelial cells and its propensity to enhance transforming growth factor beta 1 (TGFβ1)-mediated epithelial-mesenchymal transition (EMT), a process occurring during tumor progression and critical for invasion and metastasis. Non-transformed mink lung epithelial cells (Mv1Lu) and hTERT- immortalized human esophageal epithelial cells (EPC) were used in this study. EMT was identified by alterations in cell morphology, EMT-related gene expression changes determined using real-time PCR, and EMT changes in specific cellular markers detected by immunostaining and western blotting. Although TGFβ1 treatment alone is able to induce EMT in both Mv1Lu and EPC cells, low energy protons (5 MeV) at doses as low as 0.1 Gy can enhance TGFβ1 induced EMT. Protons alone can also induce a mild induction of EMT. SD208, a potent TGFβ Receptor 1 (TGFβR1) kinase inhibitor, can efficiently block TGFβ1/Smad signaling and attenuate EMT induction. We suggest a model for EMT after proton irradiation in normal and cancerous tissue based on our results that showed that low and high doses of protons can sensitize normal human epithelial cells to mesenchymal transition, more prominently in the presence of TGFβ1, but also in the absence of TGFβ1.

  12. Protons Sensitize Epithelial Cells to Mesenchymal Transition

    PubMed Central

    Wang, Minli; Hada, Megumi; Saha, Janapriya; Sridharan, Deepa M.; Pluth, Janice M.; Cucinotta, Francis A.

    2012-01-01

    Proton radiotherapy has gained more favor among oncologists as a treatment option for localized and deep-seated tumors. In addition, protons are a major constituent of the space radiation astronauts receive during space flights. The potential for these exposures to lead to, or enhance cancer risk has not been well studied. Our objective is to study the biological effects of low energy protons on epithelial cells and its propensity to enhance transforming growth factor beta 1 (TGFβ1)-mediated epithelial-mesenchymal transition (EMT), a process occurring during tumor progression and critical for invasion and metastasis. Non-transformed mink lung epithelial cells (Mv1Lu) and hTERT- immortalized human esophageal epithelial cells (EPC) were used in this study. EMT was identified by alterations in cell morphology, EMT-related gene expression changes determined using real-time PCR, and EMT changes in specific cellular markers detected by immunostaining and western blotting. Although TGFβ1 treatment alone is able to induce EMT in both Mv1Lu and EPC cells, low energy protons (5 MeV) at doses as low as 0.1 Gy can enhance TGFβ1 induced EMT. Protons alone can also induce a mild induction of EMT. SD208, a potent TGFβ Receptor 1 (TGFβR1) kinase inhibitor, can efficiently block TGFβ1/Smad signaling and attenuate EMT induction. We suggest a model for EMT after proton irradiation in normal and cancerous tissue based on our results that showed that low and high doses of protons can sensitize normal human epithelial cells to mesenchymal transition, more prominently in the presence of TGFβ1, but also in the absence of TGFβ1. PMID:22844446

  13. COMPACT PROTON INJECTOR AND FIRST ACCELERATOR SYSTEM TEST FOR COMPACT PROTON DIELECTRIC WALL CANCER THERAPY ACCELERATOR

    SciTech Connect

    Chen, Y; Guethlein, G; Caporaso, G; Sampayan, S; Blackfield, D; Cook, E; Falabella, S; Harris, J; Hawkins, S; Nelson, S; Poole, B; Richardson, R; Watson, J; Weir, J; Pearson, D

    2009-04-23

    A compact proton accelerator for cancer treatment is being developed by using the high-gradient dielectric insulator wall (DWA) technology [1-4]. We are testing all the essential DWA components, including a compact proton source, on the First Article System Test (FAST). The configuration and progress on the injector and FAST will be presented.

  14. Proton-proton bremsstrahlung calculation: Comparison with recent high-precision experimental results

    SciTech Connect

    Li Yi; Liou, M.K.; Schreiber, W.M.

    2005-08-01

    Proton-proton bremsstrahlung cross sections and analyzing powers have been calculated at 190 MeV by using a one-boson-exchange model. The results are compared with the recently published high-precision Kernfysisch-Versneller-Instituut (KVI) data. Satisfactory agreement between theory and experiment has been found.

  15. Relativistic mean-field study on proton skins and proton halos in exotic nuclei

    NASA Astrophysics Data System (ADS)

    Ren, Zhongzhou; Mittig, W.; Sarazin, F.

    1999-06-01

    We investigate the ground state properties of proton-rich nuclei in the framework of the relativistic mean-field model. Calculations show that the experimental proton halo in the nuclei 26,27,28P can be reproduced by the model. The proton halos can appear in proton-rich nuclei because the total nuclear potential is attractive up to the radial distance r ≈ 5.5 fm. But the size of proton halos is finite due to the limitation of the Coulomb potential barrier. The mean-square radius of a halo proton is not very sensitive to the separation energy of the last proton in some very proton-rich nuclei due to the effect of the Coulomb barrier. This behavior is different from the case of a neutron halo where the mean-square radius of a halo neutron is inversely proportional to the separation energy of the last halo neutron. We have also analysed the differences of the relativistic mean-field potentials of 25Al and 26P and found that the isovector potential from the p meson has an important effect on the differences.

  16. Proton-proton physics with the ALICE muon spectrometer at the LHC

    SciTech Connect

    Bastid, N.

    2008-09-15

    ALICE, the dedicated heavy-ion experiment at the LHC, has also an important proton-proton physics program. The ALICE muon spectrometer will be presented and the corresponding physics analysis will be reviewed. A particular emphasis will be placed on heavy-flavor measurement.

  17. Quantification of Proton Dose Calculation Accuracy in the Lung

    SciTech Connect

    Grassberger, Clemens; Daartz, Juliane; Dowdell, Stephen; Ruggieri, Thomas; Sharp, Greg; Paganetti, Harald

    2014-06-01

    Purpose: To quantify the accuracy of a clinical proton treatment planning system (TPS) as well as Monte Carlo (MC)–based dose calculation through measurements and to assess the clinical impact in a cohort of patients with tumors located in the lung. Methods and Materials: A lung phantom and ion chamber array were used to measure the dose to a plane through a tumor embedded in the lung, and to determine the distal fall-off of the proton beam. Results were compared with TPS and MC calculations. Dose distributions in 19 patients (54 fields total) were simulated using MC and compared to the TPS algorithm. Results: MC increased dose calculation accuracy in lung tissue compared with the TPS and reproduced dose measurements in the target to within ±2%. The average difference between measured and predicted dose in a plane through the center of the target was 5.6% for the TPS and 1.6% for MC. MC recalculations in patients showed a mean dose to the clinical target volume on average 3.4% lower than the TPS, exceeding 5% for small fields. For large tumors, MC also predicted consistently higher V5 and V10 to the normal lung, because of a wider lateral penumbra, which was also observed experimentally. Critical structures located distal to the target could show large deviations, although this effect was highly patient specific. Range measurements showed that MC can reduce range uncertainty by a factor of ∼2: the average (maximum) difference to the measured range was 3.9 mm (7.5 mm) for MC and 7 mm (17 mm) for the TPS in lung tissue. Conclusion: Integration of Monte Carlo dose calculation techniques into the clinic would improve treatment quality in proton therapy for lung cancer by avoiding systematic overestimation of target dose and underestimation of dose to normal lung. In addition, the ability to confidently reduce range margins would benefit all patients by potentially lowering toxicity.

  18. How proton pulse characteristics influence protoacoustic determination of proton-beam range: simulation studies.

    PubMed

    Jones, Kevin C; Seghal, Chandra M; Avery, Stephen

    2016-03-21

    The unique dose deposition of proton beams generates a distinctive thermoacoustic (protoacoustic) signal, which can be used to calculate the proton range. To identify the expected protoacoustic amplitude, frequency, and arrival time for different proton pulse characteristics encountered at hospital-based proton sources, the protoacoustic pressure emissions generated by 150 MeV, pencil-beam proton pulses were simulated in a homogeneous water medium. Proton pulses with Gaussian widths ranging up to 200 μs were considered. The protoacoustic amplitude, frequency, and time-of-flight (TOF) range accuracy were assessed. For TOF calculations, the acoustic pulse arrival time was determined based on multiple features of the wave. Based on the simulations, Gaussian proton pulses can be categorized as Dirac-delta-function-like (FWHM < 4 μs) and longer. For the δ-function-like irradiation, the protoacoustic spectrum peaks at 44.5 kHz and the systematic error in determining the Bragg peak range is <2.6 mm. For longer proton pulses, the spectrum shifts to lower frequencies, and the range calculation systematic error increases (⩽ 23 mm for FWHM of 56 μs). By mapping the protoacoustic peak arrival time to range with simulations, the residual error can be reduced. Using a proton pulse with FWHM = 2 μs results in a maximum signal-to-noise ratio per total dose. Simulations predict that a 300 nA, 150 MeV, FWHM = 4 μs Gaussian proton pulse (8.0 × 10(6) protons, 3.1 cGy dose at the Bragg peak) will generate a 146 mPa pressure wave at 5 cm beyond the Bragg peak. There is an angle dependent systematic error in the protoacoustic TOF range calculations. Placing detectors along the proton beam axis and beyond the Bragg peak minimizes this error. For clinical proton beams, protoacoustic detectors should be sensitive to <400 kHz (for -20 dB). Hospital-based synchrocyclotrons and cyclotrons are promising sources of proton pulses for generating clinically measurable protoacoustic

  19. Emittance and proton fraction measurement in High current electron cyclotron resonance proton ion source

    NASA Astrophysics Data System (ADS)

    Roychowdhury, P.; Kewlani, H.; Mishra, L.; Gharat, S.; Rajawat, R. K.

    2015-09-01

    The beam characterization studies in terms of emittance and proton fraction have been carried out in the high current Electron Cyclotron Resonance (ECR) proton ion source developed for Low Energy High Intensity Proton Accelerator (LEHIPA). The beam emittance was measured using two slit emittance measurement units (EMU). The emittance was measured at three locations (1) after beam extraction at ion source end, (2) after focusing the beam using solenoid magnet and (3) after focusing and separating H+ using solenoid magnet and analyzing magnet. The beam emittance measured in all three cases was found to be less than 0.2π mm-mrad (rms-normalized). The proton fraction in the beam measured using analyzing magnet was found to be more than 90%. The variations of beam emittance and proton fraction have been studied as a function of microwave power and neutral gas pressure.

  20. Neutrinos from the primary proton-proton fusion process in the Sun.

    PubMed

    2014-08-28

    In the core of the Sun, energy is released through sequences of nuclear reactions that convert hydrogen into helium. The primary reaction is thought to be the fusion of two protons with the emission of a low-energy neutrino. These so-called pp neutrinos constitute nearly the entirety of the solar neutrino flux, vastly outnumbering those emitted in the reactions that follow. Although solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun's energy and contributing to the discovery of neutrino oscillations, those from proton-proton fusion have hitherto eluded direct detection. Here we report spectral observations of pp neutrinos, demonstrating that about 99 per cent of the power of the Sun, 3.84 × 10(33) ergs per second, is generated by the proton-proton fusion process. PMID:25164748

  1. Neutrinos from the primary proton-proton fusion process in the Sun.

    PubMed

    2014-08-28

    In the core of the Sun, energy is released through sequences of nuclear reactions that convert hydrogen into helium. The primary reaction is thought to be the fusion of two protons with the emission of a low-energy neutrino. These so-called pp neutrinos constitute nearly the entirety of the solar neutrino flux, vastly outnumbering those emitted in the reactions that follow. Although solar neutrinos from secondary processes have been observed, proving the nuclear origin of the Sun's energy and contributing to the discovery of neutrino oscillations, those from proton-proton fusion have hitherto eluded direct detection. Here we report spectral observations of pp neutrinos, demonstrating that about 99 per cent of the power of the Sun, 3.84 × 10(33) ergs per second, is generated by the proton-proton fusion process.

  2. Protonated sugars: vibrational spectroscopy and conformational structure of protonated O-methyl α-D-galactopyranoside

    NASA Astrophysics Data System (ADS)

    Rudić, Svemir; Xie, Hong-bin; Gerber, R. Benny; Simons, John P.

    2012-08-01

    'Bridging' protons provide a common structural motif in biological assemblies such as proton wires and proton-bound dimers. Here we present a 'proof-of-principle' computational and vibrational spectroscopic investigation of an 'intra-molecular proton-bound dimer,' O-methyl α-D-galactopyranoside (αMeGal-H+), generated in the gas phase through photo-ionisation of its complex with phenol in a molecular beam. Its vibrational spectrum corresponds well with a classical molecular dynamics simulation conducted 'on-the-fly' and also with the lowest-energy structures predicted by DFT and ab initio calculations. They reveal proton-bound structures that bridge neighbouring pairs of oxygen atoms, preferentially O6 and O4, linked together within the carbohydrate scaffold. Motivated by the possibility of an entry into the microscopic mechanism of its acid (or enzyme)-catalysed hydrolysis, we also report the corresponding predictions for its singly hydrated complex.

  3. Study of elastic proton-proton scattering with the STAR detector at RHIC

    NASA Astrophysics Data System (ADS)

    Sikora, Rafal

    2015-09-01

    The STAR detector at the Relativistic Heavy Ion Collider (RHIC) is equipped with system of dedicated Silicon Strip Detectors housed inside Roman Pot vessels, allowing to detect protons scattered at small angles. Data from polarized proton-proton collisions at center-of-mass system (c.m.s.) energy √s = 200 GeV collected with special settings of RHIC magnet lattice (β * = 22 m) allow to study proton-proton elastic scattering at very low values of squared four-momentum transfer (Mandelstam t), 0:003 <= -t <= 0:035 GeV2=c2. Results of analysis of systematic effects and large statistics of collected data sample reveal possibility of measurement of the Nuclear Slope Parameter with precision not yet achieved at this c.m.s. energy.

  4. Pyridine as proton acceptor in the concerted proton electron transfer oxidation of phenol.

    PubMed

    Bonin, Julien; Costentin, Cyrille; Robert, Marc; Savéant, Jean-Michel

    2011-06-01

    Taking pyridine as a prototypal example of biologically important nitrogen bases involved in proton-coupled electron transfers, it is shown with the example of the photochemically triggered oxidation of phenol by Ru(III)(bpy)(3) that this proton acceptor partakes in a concerted pathway whose kinetic characteristics can be extracted from the overall kinetic response. The treatment of these data, implemented by the results of a parallel study carried out in heavy water, allowed the determination of the intrinsic kinetic characteristics of this proton acceptor. Comparison of the reorganization energies and of the pre-exponential factors previously derived for hydrogen phosphate and water (in water) as proton acceptors suggests that, in the case of pyridine, the proton charge is delocalized over a primary shell of water molecules firmly bound to the pyridinium cation. PMID:21499600

  5. Pyridine as proton acceptor in the concerted proton electron transfer oxidation of phenol.

    PubMed

    Bonin, Julien; Costentin, Cyrille; Robert, Marc; Savéant, Jean-Michel

    2011-06-01

    Taking pyridine as a prototypal example of biologically important nitrogen bases involved in proton-coupled electron transfers, it is shown with the example of the photochemically triggered oxidation of phenol by Ru(III)(bpy)(3) that this proton acceptor partakes in a concerted pathway whose kinetic characteristics can be extracted from the overall kinetic response. The treatment of these data, implemented by the results of a parallel study carried out in heavy water, allowed the determination of the intrinsic kinetic characteristics of this proton acceptor. Comparison of the reorganization energies and of the pre-exponential factors previously derived for hydrogen phosphate and water (in water) as proton acceptors suggests that, in the case of pyridine, the proton charge is delocalized over a primary shell of water molecules firmly bound to the pyridinium cation.

  6. Oblique incidence for broad monoenergetic proton beams

    SciTech Connect

    Jette, David; Yuan Jiankui; Chen Weimin

    2010-11-15

    Purpose: The depth dose of a monoenergetic broad parallel proton beam has been modeled in a number of ways, but evidently not yet for oblique incidence. The purpose of this investigation is to find an accurate analytic formula for this case, which can then be used to model the depth dose of a broad beam with an initial Gaussian angular distribution. Methods: The Bortfeld model of depth dose in a broad normally incident proton beam has been extended to the case of oblique incidence. This extension uses an empirically determined Gaussian parameter {sigma}{sub x} which (roughly) characterizes the off-axis dose of a proton pencil beam. As with Bortfeld's work, the modeling is done in terms of parabolic cylinder functions. To obtain the depth dose for an initial angular distribution, the result is integrated over the angle of incidence, weighted by a Gaussian probability function. The predictions of the theory have been compared to MCNPX Monte Carlo calculations for four phantom materials (water, bone, aluminum, and copper) and for initial proton energies of 50, 100, 150, 200, and 250 MeV. Results: Comparisons of the depth dose predicted by this theory with Monte Carlo calculations have established that with very good accuracy, {sigma}{sub x} can be taken to be independent both of the depth and of the angle of incidence. As a function of initial proton range or of initial proton energy, {sigma}{sub x} has been found to obey a power law to very high accuracy. Good fits to Monte Carlo calculations have also been found for an initial Gaussian angular distribution. Conclusions: This investigation is the first step in the accurate modeling of a proton pencil beam with initial Gaussian angular distribution. It provides the longitudinal factor, with its Bragg peak buildup and sharp distal falloff. A transverse factor must still be incorporated into this theory and this will give the lateral penumbra of a collimated proton beam. Also, it will be necessary to model the dose of

  7. Modeling and optimization of a time-resolved proton radiographic imaging system for proton cancer treatment

    NASA Astrophysics Data System (ADS)

    Han, Bin

    This dissertation describes a research project to test the clinical utility of a time-resolved proton radiographic (TRPR) imaging system by performing comprehensive Monte Carlo simulations of a physical device coupled with realistic lung cancer patient anatomy defined by 4DCT for proton therapy. A time-resolved proton radiographic imaging system was modeled through Monte Carlo simulations. A particle-tracking feature was employed to evaluate the performance of the proton imaging system, especially in its ability to visualize and quantify proton range variations during respiration. The Most Likely Path (MLP) algorithm was developed to approximate the multiple Coulomb scattering paths of protons for the purpose of image reconstruction. Spatial resolution of ˜ 1 mm and range resolution of 1.3% of the total range were achieved using the MLP algorithm. Time-resolved proton radiographs of five patient cases were reconstructed to track tumor motion and to calculate water equivalent length variations. By comparing with direct 4DCT measurement, the accuracy of tumor tracking was found to be better than 2 mm in five patient cases. Utilizing tumor tracking information to reduce margins to the planning target volume, a gated treatment plan was compared with un-gated treatment plan. The equivalent uniform dose (EUD) and the normal tissue complication probability (NTCP) were used to quantify the gain in the quality of treatments. The EUD of the OARs was found to be reduced up to 11% and the corresponding NTCP of organs at risk (OARs) was found to be reduced up to 16.5%. These results suggest that, with image guidance by proton radiography, dose to OARs can be reduced and the corresponding NTCPs can be significantly reduced. The study concludes that the proton imaging system can accurately track the motion of the tumor and detect the WEL variations, leading to potential gains in using image-guided proton radiography for lung cancer treatments.

  8. Moving Protons with Pendant Amines: Proton Mobility in a Nickel Catalyst for Oxidation of Hydrogen

    SciTech Connect

    O'Hagan, Molly J.; Shaw, Wendy J.; Raugei, Simone; Chen, Shentan; Yang, Jenny Y.; Kilgore, Uriah J.; DuBois, Daniel L.; Bullock, R. Morris

    2011-09-14

    One dimensional variable temperature NMR techniques and two dimensional EXSY experiments provide rate constants for proton exchange processes in [Ni(PCy2NBz2)2]2+, an electrocatalyst for oxidation of H2 (PCy2NBz2 = 1,5-diphenyl-3,7-dibenzyl-1,5-diaza-3,7-diphosphacyclooctane). Computational studies provide insight into the details of the proton movement and energetics of these complexes, which contain pendant amines that function as proton relays. Intramolecular proton exchange processes are observed for two of the three experimentally observable isomers of [Ni(PCy2NBzH2)2]2+, which have two N-H bonds but no Ni-H bonds. For these two isomers, the rate constants range from 10{sup 3} to 10{sup 4} s{sup -1}, depending on isomer and solvent. Analysis of the exchange as a function of temperature yielded a barrier for proton exchange for both isomers of {Delta}G{sub {double_dagger}} = 11-12 kcal/mol, with little dependence on solvent. Density functional theory calculations and molecular dynamics simulations support the experimental observations, suggesting a metal-mediated intramolecular proton transfer. Intermolecular proton exchange was not observed on either of these timescales (10{sup -2} s{sup -1} to 10{sup 4} s{sup -1}). The fast rate of proton movement within the catalyst has important implications for the availability of protons during catalysis and may also have implications for the proton channel in the Ni-Fe hydrogenase enzyme.

  9. Mixing of Proton and Electron Scales - Effects of Proton Temperature Anisotropy on the Electron Firehose Instability

    NASA Astrophysics Data System (ADS)

    Maneva, Y. G.; Lazar, M.; Vinas, A. F.; Poedts, D. S.

    2015-12-01

    We perform kinetic linear theory instability analysis in a non-drifting anisotropic electron-proton plasma to study the effects of proton temperature anisotropies on the electron firehose instability in the collisionless solar wind. We solve the Vlasov linear theory dispersion relation for hot highly anisotropic electron-proton plasma in high-beta regime to study the behavior of the solar wind plasma close to the instability thresholds as observed by different spacecraft at 1 AU. We consider temperature and anisotropy regimes for which the electrons and the protons can interact via the excited electromagnetic fluctuations. For the selected parameters simultaneous electron and proton firehose instabilities can be observed with the growth rate of the electron firehose instability extending towards the proton scales. The co-existance of the proton and the electron firehose and the mixing of scales for the electromagnetic fluctuations excited by the two instabilities depends on the initial temperatures, anisotropies and angle of propagation. In the case of parallel wave propagation both left and right-hand polarized waves are simultaneously excited. As we increase the angle of propagation the electron firehose starts to dominate with excitation of large-amplitude aperiodic fluctuations over a large range of wave-numbers, starting at the protons scales and extending up to the smaller electron scales. We calculate the maximum growth rate of the oblique electron firehose as a function of the proton temperature anisotropy and discuss the implications of the electron-proton scale mixing for the observed plasma properties and instability thresholds in the undisturbed solar wind.

  10. A New High-Current Proton Accelerator

    NASA Astrophysics Data System (ADS)

    Cleland, M. R.; Galloway, R. A.; DeSanto, L.; Jongen, Y.

    2009-03-01

    A high-current (>20 mA) dc proton accelerator is being developed for applications such as boron neutron capture therapy (BNCT) and the detection of explosive materials by nuclear resonance absorption (NRA) of gamma radiation. The high-voltage dc accelerator (adjustable between 1.4 and 2.8 MeV) will be a single-ended industrial Dynamitron® system equipped with a compact high-current, microwave-driven proton source. A magnetic mass analyzer inserted between the ion source and the acceleration tube will select the protons and reject heavier ions. A sorption pump near the ion source will minimize the flow of neutral hydrogen gas into the acceleration tube. For BNCT, a lithium target for generating epithermal neutrons is being developed that will be capable of dissipating the high power (>40 kW) of the proton beam. For NRA, special targets will be used to generate gamma rays with suitable energies for exciting nuclides typically present in explosive materials. Proton accelerators with such high-current and high-power capabilities in this energy range have not been developed previously.

  11. Proton transfer pathways in Photosystem II

    NASA Astrophysics Data System (ADS)

    Ishikita, Hiroshi

    2014-03-01

    Using quantum mechanics/molecular mechanics calculations and the 1.9-Å crystal structure of Photosystem II (Umena, Y., Kawakami, K., Shen, J.-R., and Kamiya, N. (2011) Nature 473, 55-60), we investigated the H-bonding environment of the redox active tyrosine, TyrD and obtained insights that help explain its slow redox kinetics and the stability of TyrD radical. The water molecule distal to TyrD, 4 Å away from the phenolic O of TyrD (OTyrD) , corresponds to the presence of the tyrosyl radical state. The water molecule proximal to TyrD, in H-bonding distance to OTyrD, corresponds to the presence of the unoxidised tyrosine. The H+ released upon oxidation of TyrD is transferred to the proximal water, which shifts to the distal position, triggering a concerted proton transfer pathway involving D2-Arg180 and a series of waters, through which the proton reaches the aqueous phase at D2-His61. The water movement linked to the ejection of the proton from the hydrophobic environment near TyrD makes oxidation slow and quasi-irreversible, explaining the great stability of the TyrD radical. A symmetry-related proton pathway associated with TyrZ is pointed out and this is associated with one of the Cl- sites. This may represent a proton pathway functional in the water oxidation cycle.

  12. A Detector for Proton Computed Tomography

    SciTech Connect

    Blazey, G.; et al.,

    2013-12-06

    Radiation therapy is a widely recognized treatment for cancer. Energetic protons have distinct features that set them apart from photons and make them desirable for cancer therapy as well as medical imaging. The clinical interest in heavy ion therapy is due to the fact that ions deposit almost all of their energy in a sharp peak – the Bragg peak- at the very end of their path. Proton beams can be used to precisely localize a tumor and deliver an exact dose to the tumor with small doses to the surrounding tissue. Proton computed tomography (pCT) provides direct information on the location on the target tumor, and avoids position uncertainty caused by treatment planning based on imaging with X-ray CT. The pCT project goal is to measure and reconstruct the proton relative stopping power distribution directly in situ. To ensure the full advantage of cancer treatment with 200 MeV proton beams, pCT must be realized.

  13. Proton irradiation study of GFR candidate ceramics

    NASA Astrophysics Data System (ADS)

    Gan, Jian; Yang, Yong; Dickson, Clayton; Allen, Todd

    2009-06-01

    This work investigated the microstructural response of SiC, ZrC and ZrN irradiated with 2.6 MeV protons at 800 °C to a fluence of 2.75 × 10 19 protons/cm 2, corresponding to 0.71-1.8 displacement per atom (dpa), depending on the material. The change of lattice constant evaluated using HOLZ patterns is not observed. In comparison to Kr ion irradiation at 800 °C to 10 dpa from the previous studies, the proton irradiated ZrC and ZrN at 1.8 dpa show less irradiation damage to the lattice structure. The proton irradiated ZrC exhibits faulted loops which are not observed in the Kr ion irradiated sample. ZrN shows the least microstructural change from proton irradiation. The microstructure of 6H-SiC irradiated to 0.71 dpa consists of black dot defects at high density.

  14. Simulation study of proton transport in ionomers

    NASA Astrophysics Data System (ADS)

    Taylor, Philip; Allahyarov, Elshad

    2008-03-01

    Coarse-grained molecular-dynamics simulations were used to study the morphological changes induced in a Nafion-like ionomer by the imposition of a strong electric field. We observe that proton transport through this polymer electrolyte membrane is accompanied by morphological changes that include the formation of structures aligned along the direction of the applied field. The polar head groups of the ionomer side chains assemble into clusters, which then form rod-like formations, and these cylindrical structures then assemble into a hexagonally ordered array aligned with the direction of current flow. For dry ionomers, at current densities in excess of 1 A/cm^2 these rod-like clusters undergo an inner micro-phase separation, in which distinct wire-like lines of sulfonate head groups are accompanied by similar wire-like alignments of bound protons. The clusters appear to be of two types. If there are two, four, or five lines of sulfonates then there is an equal number of lines of protons, but if there are three lines of sulfonates then they are accompanied by four lines of protons. Occasionally these lines of sulfonates and protons form a helical structure. Upon removal of the electric field, the hexagonal array of rod-like structures remains, but the microphase separation disappears below the threshold current of 1 A/cm^2.

  15. Voltage-gated proton channels: what' next?

    PubMed Central

    DeCoursey, Thomas E

    2008-01-01

    This review is an attempt to identify and place in context some of the many questions about voltage-gated proton channels that remain unsolved. As the gene was identified only 2 years ago, the situation is very different than in fields where the gene has been known for decades. For the proton channel, most of the obvious and less obvious structure–function questions are still wide open. Remarkably, the proton channel protein strongly resembles the voltage-sensing domain of many voltage-gated ion channels, and thus offers a novel approach to study gating mechanisms. Another surprise is that the proton channel appears to function as a dimer, with two separate conduction pathways. A number of significant biological questions remain in dispute, unanswered, or in some cases, not yet asked. This latter deficit is ascribable to the intrinsic difficulty in evaluating the importance of one component in a complex system, and in addition, to the lack, until recently, of a means of performing an unambiguous lesion experiment, that is, of selectively eliminating the molecule in question. We still lack a potent, selective pharmacological inhibitor, but the identification of the gene has allowed the development of powerful new tools including proton channel antibodies, siRNA and knockout mice. PMID:18801839

  16. Proton channels and exchangers in cancer.

    PubMed

    Spugnini, Enrico Pierluigi; Sonveaux, Pierre; Stock, Christian; Perez-Sayans, Mario; De Milito, Angelo; Avnet, Sofia; Garcìa, Abel Garcìa; Harguindey, Salvador; Fais, Stefano

    2015-10-01

    Although cancer is characterized by an intratumoral genetic heterogeneity, a totally deranged pH control is a common feature of most cancer histotypes. Major determinants of aberrant pH gradient in cancer are proton exchangers and transporters, including V-ATPase, Na+/H+ exchanger (NHE), monocarboxylate transporters (MCTs) and carbonic anhydrases (CAs). Thanks to the activity of these proton transporters and exchangers, cancer becomes isolated and/or protected not only from the body reaction against the growing tumor, but also from the vast majority of drugs that when protonated into the acidic tumor microenvironment do not enter into cancer cells. Proton transporters and exchangers represent a key feature tumor cells use to survive in the very hostile microenvironmental conditions that they create and maintain. Detoxifying mechanisms may thus represent both a key survival option and a selection outcome for cells that behave as unicellular microorganisms rather than belonging to an organ, compartment or body. It is, in fact, typical of malignant tumors that, after a clinically measurable yet transient initial response to a therapy, resistant tumor clones emerge and proliferate, thus bursting a more malignant behavior and rapid tumor progression. This review critically presents the background of a novel and efficient approach that aims to fight cancer through blocking or inhibiting well characterized proton exchangers and transporters active in human cancer cells. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

  17. Interplanetary proton fluence model - JPL 1991

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Spitale, G.; Wang, J.; Gabriel, S.

    1993-01-01

    We describe an updated predictive engineering model for the interplanetary fluence of protons with energies respectively greater than 1, 4, 10, 30, and 60 MeV. This has been the first opportunity to derive a model from a data set that has been collected in space over a long enough period of time to produce a valid sample of solar proton events. The model provides a quantitative basis for estimating the exposures to solar protons of spacecraft during missions of varying length and of surfaces and atmospheres of solar system objects. The data sets contain several major proton events comparable to the 1972 event. For the cases of the over 10 and over 30 MeV particles, the fluences are somewhat lower than in our earlier model No over 1, over 4, and over 60 MeV proton fluence models have been published in the literature previously. We present our results in a convenient graphical form which may be used to calculate the 1 AU fluence expected at a given confidence level as a function of the length of the exposure. A method of extending this estimate to other heliocentric distances is described.

  18. Proton emission from a laser ion source

    SciTech Connect

    Torrisi, L.; Cavallaro, S.; Gammino, S.; Cutroneo, M.; Margarone, D.

    2012-02-15

    At intensities of the order of 10{sup 10} W/cm{sup 2}, ns pulsed lasers can be employed to ablate solid bulk targets in order to produce high emission of ions at different charge state and kinetic energy. A special interest is devoted to the production of protons with controllable energy and current from a roto-translating target irradiated in repetition rate at 1-10 Hz by a Nd:Yag pulsed laser beam. Different hydrogenated targets based on polymers and hydrates were irradiated in high vacuum. Special nanostrucutres can be embedded in the polymers in order to modify the laser absorption properties and the amount of protons to be accelerated in the plasma. For example, carbon nanotubes may increase the laser absorption and the hydrogen absorption to generate high proton yields from the plasma. Metallic nanostrucutres may increase the electron density of the plasma and the kinetic energy of the accelerated protons. Ion collectors, ion energy analyzer, and mass spectrometers, used in time-of-flight configuration, were employed to characterize the ion beam properties. A comparison with traditional proton ion source is presented and discussed.

  19. Proton pump of clathrin-coated vesicles

    SciTech Connect

    Xie, X.

    1985-01-01

    Clathrin-coated vesicles were prepared from bovine brain catalyze ATP-driven proton translocation and a /sup 32/Pi-ATP exchange reaction. N-ethylmaleimide (NEM) at 1 mM and dicyclohexylcarbodiimide (DCCD) at 0.5 mM inhibit the pump completely, whereas neither vanadate, efrapeptin, NaN/sub 3/, nor mitochondrial ATPase inhibitor has an effect. The coated vesicle proton pump is characterized by ATP specificity. dATP, but no other nucleotide, can replace ATP as a substrate. The pump is electrogenic and the electrogenicity is neutralized by chloride or bromide serving as co-ions. ATP-driven proton translocation can be observed in the absence of chloride, provided that the membrane potential is collapsed by K/sup +/ moving out in the presence of valinomycin. Chloride transport can be observed independent of proton movements in the absence of ATP, provided that an inside positive membrane potential is generated by K/sup +/ influx in the presence of valinomycin. The proton-translocating ATPase of coated vesicles was solubilized with a nonionic detergent polyoxyethylene 9 lauryl ether, and purified about 700 fold to near homogeneity. During purification the enzymatic activity was lost. A purified brain phospholipid fraction restored the activity and was subsequently identified as phosphatidylserine.

  20. Energy Production Demonstrator for Megawatt Proton Beams

    SciTech Connect

    Pronskikh, Vitaly S.; Mokhov, Nikolai V.; Novitski, Igor; Tyutyunnikov, Sergey I.

    2014-07-16

    A preliminary study of the Energy Production Demonstrator (EPD) concept - a solid heavy metal target irradiated by GeV-range intense proton beams and producing more energy than consuming - is carried out. Neutron production, fission, energy deposition, energy gain, testing volume and helium production are simulated with the MARS15 code for tungsten, thorium, and natural uranium targets in the proton energy range 0.5 to 120 GeV. This study shows that the proton energy range of 2 to 4 GeV is optimal for both a natU EPD and the tungsten-based testing station that would be the most suitable for proton accelerator facilities. Conservative estimates, not including breeding and fission of plutonium, based on the simulations suggest that the proton beam current of 1 mA will be sufficient to produce 1 GW of thermal output power with the natU EPD while supplying < 8% of that power to operate the accelerator. The thermal analysis shows that the concept considered has a problem due to a possible core meltdown; however, a number of approaches (a beam rastering, in first place) are suggested to mitigate the issue. The efficiency of the considered EPD as a Materials Test Station (MTS) is also evaluated in this study.

  1. Contribution of proton and electron precipitation to the observed electron concentration in October-November 2003 and September 2005

    NASA Astrophysics Data System (ADS)

    Verronen, P. T.; Andersson, M. E.; Kero, A.; Enell, C.-F.; Wissing, J. M.; Talaat, E. R.; Kauristie, K.; Palmroth, M.; Sarris, T. E.; Armandillo, E.

    2015-03-01

    Understanding the altitude distribution of particle precipitation forcing is vital for the assessment of its atmospheric and climate impacts. However, the proportion of electron and proton forcing around the mesopause region during solar proton events is not always clear due to uncertainties in satellite-based flux observations. Here we use electron concentration observations of the European Incoherent Scatter Scientific Association (EISCAT) incoherent scatter radars located at Tromsø (69.58° N, 19.23° E) to investigate the contribution of proton and electron precipitation to the changes taking place during two solar proton events. The EISCAT measurements are compared to the results from the Sodankylä Ion and Neutral Chemistry Model (SIC). The proton ionization rates are calculated by two different methods - a simple energy deposition calculation and the Atmospheric Ionization Model Osnabrück (AIMOS v1.2), the latter providing also the electron ionization rates. Our results show that in general the combination of AIMOS and SIC is able to reproduce the observed electron concentration within ± 50% when both electron and proton forcing is included. Electron contribution is dominant above 90 km, and can contribute significantly also in the upper mesosphere especially during low or moderate proton forcing. In the case of strong proton forcing, the AIMOS electron ionization rates seem to suffer from proton contamination of satellite-based flux data. This leads to overestimation of modelled electron concentrations by up to 90% between 75-90 km and up to 100-150% at 70-75 km. Above 90 km, the model bias varies significantly between the events. Although we cannot completely rule out EISCAT data issues, the difference is most likely a result of the spatio-temporal fine structure of electron precipitation during individual events that cannot be fully captured by sparse in situ flux (point) measurements, nor by the statistical AIMOS model which is based upon these

  2. An Observational Test of the Stability of Inner Belt Protons Above 60 Mev Using Measurements Separated By 41 Years

    NASA Astrophysics Data System (ADS)

    Mazur, J. E.; O'Brien, T. P., III; Looper, M. D.; Blake, J. B.; George, J. S.

    2014-12-01

    The relative stability of protons trapped in the inner Van Allen radiation belt is a unique signature of the near-Earth radiation environment. While the outer electron belt changes its topography and intensity on timescales of less than a day, calculations indicate that protons in the deepest portions of the inner belt can remain on drift shells for centuries. The long lifetimes for equatorially mirroring protons have never been experimentally verified because few missions traverse this challenging environment, and those that have attempted to quantify the proton flux there have faced potentially large backgrounds from penetrating protons outside the instrument field of view. Today, the Relativistic Proton Spectrometer (RPS) investigation on board the Van Allen Probes offers a background-free reference and hence a unique opportunity to compare the present state of inner belt protons with prior measurements. In this study we revisit one relatively clean, and possibly the most accurate historical dataset: a Cherenkov proton spectrometer that operated in a highly inclined 132x1932 km orbit in 1971. The OV1-20P proton spectrometer covered the energy range of ~65-550 MeV (completely within the RPS energy range), had good background rejection because of a fast scintillator coincidence requirement, but operated off of a flight battery for only 10 days. The short lifetime of the OV1-20P mission is the primary reason it did not have significant impact on subsequent studies of the inner belt. At the meeting we will report on a comparison of OV1-20P and RPS fluxes at the same magnetic field coordinates. Our 41-year measurement baseline is not anywhere near a continuous record of course, but it is rare in space science that we have the opportunity to measure a trapped radiation environment on the timescale of decades.

  3. Protein Mediated Magnetic Coupling between Lactate and Water Protons

    NASA Astrophysics Data System (ADS)

    Swanson, Scott D.

    1998-11-01

    The magnetic coupling between methyl lactate protons and water protons in samples of cross-linked bovine serum albumin (BSA) is studied. Cross-relaxation spectroscopy shows efficient magnetization transfer from immobilized BSA to both water and methyl lactate protons. Transient and steady-state NOE experiments reveal a negative intermolecular NOE between methyl lactate and water protons. Lactate is indirectly detected by selectively saturating the methyl lactate protons and measuring the decrease in water proton magnetization. Indirect detection of methyl lactate protons is an order of magnitude more sensitive than direct detection in these model systems. Lactate was indirectly imaged, via the water proton resonance, with 1.1-μl voxels in 2 min. Immobilized BSA reduces the intermolecular correlation time between water and lactate protons into the spin-diffusion limit where the NOE is negative. Possible molecular mechanisms for this coupling and applications toin vivospectroscopy are discussed.

  4. Measurement of neutral strange particle production in the underlying event in proton-proton collisions at sqrt(s) = 7 TeV

    SciTech Connect

    Chatrchyan, Serguei; et al.

    2013-09-01

    Measurements are presented of the production of primary K(S)0 and Lambda particles in proton-proton collisions at sqrt(s) = 7 TeV in the region transverse to the leading charged-particle jet in each event. The average multiplicity and average scalar transverse momentum sum of K(S)0 and Lambda particles measured at pseudorapidities abs(eta) < 2 rise with increasing charged-particle jet pt in the range 1-10 GeV and saturate in the region 10-50 GeV. The rise and saturation of the strange particle yields and transverse momentum sums in the underlying event are similar to those observed for inclusive charged particles, which confirms the impact-parameter picture of multiple parton interactions. The results are compared to recent tunes of the PYTHIA Monte Carlo event generator. The PYTHIA simulations underestimate the data by 15-30% for K(S)0 mesons and by about 50% for Lambda baryons, a deficit similar to that observed for the inclusive strange particle production in non-single-diffractive proton-proton collisions. The constant strange- to charged-particle activity ratios and the similar trends for mesons and baryons indicate that the multiparton-interaction dynamics is decoupled from parton hadronization, which occurs at a later stage.

  5. Comparison of the secondary electrons produced by proton and electron beams in water

    NASA Astrophysics Data System (ADS)

    Kia, Mohammad Reza; Noshad, Houshyar

    2016-05-01

    The secondary electrons produced in water by electron and proton beams are compared with each other. The total ionization cross section (TICS) for an electron impact in water is obtained by using the binary-encounter-Bethe model. Hence, an empirical equation based on two adjustable fitting parameters is presented to determine the TICS for proton impact in media. In order to calculate the projectile trajectory, a set of stochastic differential equations based on the inelastic collision, elastic scattering, and bremsstrahlung emission are used. In accordance with the projectile trajectory, the depth dose deposition, electron energy loss distribution in a certain depth, and secondary electrons produced in water are calculated. The obtained results for the depth dose deposition and energy loss distribution in certain depth for electron and proton beams with various incident energies in media are in excellent agreement with the reported experimental data. The difference between the profiles for the depth dose deposition and production of secondary electrons for a proton beam can be ignored approximately. But, these profiles for an electron beam are completely different due to the effect of elastic scattering on electron trajectory.

  6. Effects of Proton and Combined Proton and (56)Fe Radiation on the Hippocampus.

    PubMed

    Raber, Jacob; Allen, Antiño R; Sharma, Sourabh; Allen, Barrett; Rosi, Susanna; Olsen, Reid H J; Davis, Matthew J; Eiwaz, Massarra; Fike, John R; Nelson, Gregory A

    2016-01-01

    The space radiation environment contains protons and (56)Fe, which could pose a significant hazard to space flight crews during and after missions. The space environment involves complex radiation exposures, thus, the effects of a dose of protons might be modulated by a dose of heavy-ion radiation. The brain, and particularly the hippocampus, may be susceptible to space radiation-induced changes. In this study, we first determined the dose-response effect of proton radiation (150 MeV) on hippocampus-dependent cognition 1 and 3 months after exposure. Based on those results, we subsequently exposed mice to protons alone (150 MeV, 0.1 Gy), (56)Fe alone (600 MeV/n, 0.5 Gy) or combined proton and (56)Fe radiations (protons first) with the two exposures separated by 24 h. At one month postirradiation, all animal groups showed novel object recognition. However, at three months postirradiation, mice exposed to either protons or combined proton and (56)Fe radiations showed impaired novel object recognition, which was not observed in mice irradiated with (56)Fe alone. The mechanisms in these impairments might involve inflammation. In mice irradiated with protons alone or (56)Fe alone three months earlier, there was a negative correlation between a measure of novel object recognition and the number of newly born activated microglia in the dentate gyrus. Next, cytokine and chemokine levels were assessed in the hippocampus. At one month after exposure the levels of IL-12 were higher in mice exposed to combined radiations compared with sham-irradiated mice, while the levels of IFN-γ were lower in mice exposed to (56)Fe radiation alone or combined radiations. In addition, IL-4 levels were lower in (56)Fe-irradiated mice compared with proton-irradiated mice and TNF-α levels were lower in proton-irradiated mice than in mice receiving combined radiations. At three months after exposure, macrophage-derived chemokine (MDC) and eotaxin levels were lower in mice receiving combined

  7. Effects of Proton and Combined Proton and (56)Fe Radiation on the Hippocampus.

    PubMed

    Raber, Jacob; Allen, Antiño R; Sharma, Sourabh; Allen, Barrett; Rosi, Susanna; Olsen, Reid H J; Davis, Matthew J; Eiwaz, Massarra; Fike, John R; Nelson, Gregory A

    2016-01-01

    The space radiation environment contains protons and (56)Fe, which could pose a significant hazard to space flight crews during and after missions. The space environment involves complex radiation exposures, thus, the effects of a dose of protons might be modulated by a dose of heavy-ion radiation. The brain, and particularly the hippocampus, may be susceptible to space radiation-induced changes. In this study, we first determined the dose-response effect of proton radiation (150 MeV) on hippocampus-dependent cognition 1 and 3 months after exposure. Based on those results, we subsequently exposed mice to protons alone (150 MeV, 0.1 Gy), (56)Fe alone (600 MeV/n, 0.5 Gy) or combined proton and (56)Fe radiations (protons first) with the two exposures separated by 24 h. At one month postirradiation, all animal groups showed novel object recognition. However, at three months postirradiation, mice exposed to either protons or combined proton and (56)Fe radiations showed impaired novel object recognition, which was not observed in mice irradiated with (56)Fe alone. The mechanisms in these impairments might involve inflammation. In mice irradiated with protons alone or (56)Fe alone three months earlier, there was a negative correlation between a measure of novel object recognition and the number of newly born activated microglia in the dentate gyrus. Next, cytokine and chemokine levels were assessed in the hippocampus. At one month after exposure the levels of IL-12 were higher in mice exposed to combined radiations compared with sham-irradiated mice, while the levels of IFN-γ were lower in mice exposed to (56)Fe radiation alone or combined radiations. In addition, IL-4 levels were lower in (56)Fe-irradiated mice compared with proton-irradiated mice and TNF-α levels were lower in proton-irradiated mice than in mice receiving combined radiations. At three months after exposure, macrophage-derived chemokine (MDC) and eotaxin levels were lower in mice receiving combined

  8. Proton magnetic resonance spectroscopy in multiple sclerosis

    SciTech Connect

    Wolinsky, J.S.; Narayana, P.A.; Fenstermacher, M.J. )

    1990-11-01

    Regional in vivo proton magnetic resonance spectroscopy provides quantitative data on selected chemical constituents of brain. We imaged 16 volunteers with clinically definite multiple sclerosis on a 1.5 tesla magnetic resonance scanner to define plaque-containing volumes of interest, and obtained localized water-suppressed proton spectra using a stimulated echo sequence. Twenty-five of 40 plaque-containing regions provided spectra of adequate quality. Of these, 8 spectra from 6 subjects were consistent with the presence of cholesterol or fatty acids; the remainder were similar to those obtained from white matter of normal volunteers. This early experience with regional proton spectroscopy suggests that individual plaques are distinct. These differences likely reflect dynamic stages of the evolution of the demyelinative process not previously accessible to in vivo investigation.

  9. Data analysis for Skylab proton spectrometer

    NASA Technical Reports Server (NTRS)

    Hill, C. W.

    1975-01-01

    The measured values are compared to values derived from a proton environment model. Spectral data are compared, the omni-directional fluxes are found, a range of assumed pitch angle distributions are established, and the values which would be seen by an idealized proton spectrometer immersed in the model environment are computed. The measured values and calculated values are summed over time, then ratiod to provide spectral correction factors. The data are tabulated according to location, pitch angle, energy, assumed pitch angle distribution, and orientation in the earth-fixed coordinate system. With the aid of this data, detailed corrections to the proton model environment are derived. Best-fit, energy-dependent pitch angle distributions are also obtained. Some information is derived concerning the east-west asymmetry.

  10. Proton radioactivity studies at the FMA

    SciTech Connect

    Penttila, H. ||; Davids, C.N.; Woods, P.J.

    1995-12-31

    A double sided silicon strip (DSSD) setup is installed at the Argonne National Laboratory recoil separator FMA. Ground state proton emitters {sup 146,147}Tm, {sup 160}Re, {sup 156}Ta, {sup 150,151}Lu were produced in a series of test experiments. Improved T{sub 1/2} values were obtained for {sup 147}Tm, {sup 160}Re, and {sup 156}Ta. Improved alpha T{sub 1/2} value of (13.2 {plus_minus} 1.1) ms was obtained for {sup 161}Re. In a search of new proton radioactivities a (5 {plus_minus} 2)% proton decay branch with E{sub p} = (1345 {plus_minus} 13) keV for {sup 161}Re was found.

  11. Moving protons and electrons in biomimetic systems.

    PubMed

    Warren, Jeffrey J; Mayer, James M

    2015-03-17

    An enormous variety of biological redox reactions are accompanied by changes in proton content at enzyme active sites, in their associated cofactors, in substrates and/or products, and between protein interfaces. Understanding this breadth of reactivity is an ongoing chemical challenge. A great many workers have developed and investigated biomimetic model complexes to build new ways of thinking about the mechanistic underpinnings of such complex biological proton-coupled electron transfer (PCET) reactions. Of particular importance are those model reactions that involve transfer of one proton (H(+)) and one electron (e(-)), which is equivalent to transfer of a hydrogen atom (H(•)). In this Current Topic, we review key concepts in PCET reactivity and describe important advances in biomimetic PCET chemistry, with a special emphasis on research that has enhanced efforts to understand biological PCET reactions.

  12. A Superconducting Linac Proton Driver at Fermilab

    NASA Astrophysics Data System (ADS)

    Foster, G. William

    2004-05-01

    A proton driver has emerged as the leading candidate for Fermilab's next near-term accelerator project. The preferred technical solution is an 8 GeV superconducting linac based on technology developed for TESLA and the Spallation Neutron Source (SNS). Its primary mission is to serve as a single-stage H- injector to prepare 2 MW "Super-Beams" for Neutrino experiments using the Fermilab Main Injector. The linac can also accelerate electrons, protons, and relativistic muons, permitting future applications such as a driver for an FEL, a long-pulse spallation source, the driver for an intense 8 GeV neutrino or kaon program, and potential applications to a neutrino factory or muon collider. The technical design of the 8 GeV linac, as well as the design of an alternative synchrotron based proton driver, will be described along with plans for project proposal and construction.

  13. Polarization measurement of laser-accelerated protons

    SciTech Connect

    Raab, Natascha; Engels, Ralf; Engin, Ilhan; Greven, Patrick; Holler, Astrid; Lehrach, Andreas; Maier, Rudolf; Büscher, Markus; Cerchez, Mirela; Swantusch, Marco; Toncian, Monika; Toncian, Toma; Willi, Oswald; Gibbon, Paul; Karmakar, Anupam

    2014-02-15

    We report on the successful use of a laser-driven few-MeV proton source to measure the differential cross section of a hadronic scattering reaction as well as on the measurement and simulation study of polarization observables of the laser-accelerated charged particle beams. These investigations were carried out with thin foil targets, illuminated by 100 TW laser pulses at the Arcturus laser facility; the polarization measurement is based on the spin dependence of hadronic proton scattering off nuclei in a Silicon target. We find proton beam polarizations consistent with zero magnitude which indicates that for these particular laser-target parameters the particle spins are not aligned by the strong magnetic fields inside the laser-generated plasmas.

  14. PRaVDA: High Energy Physics towards proton Computed Tomography

    NASA Astrophysics Data System (ADS)

    Price, T.

    2016-07-01

    Proton radiotherapy is an increasingly popular modality for treating cancers of the head and neck, and in paediatrics. To maximise the potential of proton radiotherapy it is essential to know the distribution, and more importantly the proton stopping powers, of the body tissues between the proton beam and the tumour. A stopping power map could be measured directly, and uncertainties in the treatment vastly reduce, if the patient was imaged with protons instead of conventional x-rays. Here we outline the application of technologies developed for High Energy Physics to provide clinical-quality proton Computed Tomography, in so reducing range uncertainties and enhancing the treatment of cancer.

  15. Photoresponsive molecular switch for regulating transmembrane proton-transfer kinetics.

    PubMed

    Li, Ying; Tse, Edmund C M; Barile, Christopher J; Gewirth, Andrew A; Zimmerman, Steven C

    2015-11-11

    To control proton delivery across biological membranes, we synthesized a photoresponsive molecular switch and incorporated it in a lipid layer. This proton gate was reversibly activated with 390 nm light (Z-isomer) and then deactivated by 360 nm irradiation (E-isomer). In a lipid layer this stimuli responsive proton gate allowed the regulation of proton flux with irradiation to a lipid-buried O2 reduction electrocatalyst. Thus, the catalyst was turned on and off with the E-to-Z interconversion. This light-induced membrane proton delivery system may be useful in developing any functional device that performs proton-coupled electron-transfer reactions.

  16. Comment on 'Proton beam monitor chamber calibration'.

    PubMed

    Palmans, Hugo; Vatnitsky, Stanislav M

    2016-09-01

    We comment on a recent article (Gomà et al 2014 Phys. Med. Biol. 59 4961-71) which compares different routes of reference dosimetry for the energy dependent beam monitor calibration in scanned proton beams. In this article, a 3% discrepancy is reported between a Faraday cup and a plane-parallel ionization chamber in the experimental determination of the number of protons per monitor unit. It is further claimed that similar discrepancies between calorimetry and ionization chamber based dosimetry indicate that [Formula: see text]-values tabulated for proton beams in IAEA TRS-398 might be overestimated. In this commentary we show, however, that this supporting argument misrepresents the evidence in the literature and that the results presented, together with published data, rather confirm that there exist unresolved problems with Faraday cup dosimetry. We also show that the comparison in terms of the number of protons gives a biased view on the uncertainty estimates for both detectors while the quantity of interest is absorbed dose to water or dose-area-product to water, even if a beam monitor is calibrated in terms of the number of protons. Gomà et al (2014 Phys. Med. Biol. 59 4961-71) also report on the discrepancy between cylindrical and plane-parallel ionization chambers and confirm experimentally that in the presence of a depth dose gradient, theoretical values of the effective point of measurement, or alternatively a gradient correction factor, account for the discrepancy. We believe this does not point to an error or shortcoming of IAEA TRS-398, which prescribes taking the centre of cylindrical ionization chambers as reference point, since it recommends reference dosimetry to be performed in the absence of a depth dose gradient. But these observations reveal that important aspects of beam monitor calibration in scanned proton beams are not addressed in IAEA TRS-398 given that those types of beams were not widely implemented at the time of its publication

  17. Structural determinants of proton blockage in aquaporins.

    PubMed

    Chakrabarti, Nilmadhab; Roux, Benoît; Pomès, Régis

    2004-10-15

    Aquaporins are an important class of membrane channels selective for water and linear polyols but impermeable to ions, including protons. Recent computational studies have revealed that the relay of protons through the water-conduction pathway of aquaporin channels is opposed by a substantial free energy barrier peaking at the signature NPA motifs. Here, free-energy simulations and continuum electrostatic calculations are combined to examine the nature and the magnitude of the contribution of specific structural elements to proton blockage in the bacterial glycerol uptake facilitator, GlpF. Potential of mean-force profiles for both hop and turn steps of structural diffusion in the narrow pore are obtained for artificial variants of the GlpF channel in which coulombic interactions between the pore contents and conserved residues Asn68 and Asn203 at the NPA signature motifs, Arg206 at the selectivity filter, and the peptidic backbone of the two half-helices M3 and M7, which are arranged in head-to-head fashion around the NPA motifs, are turned off selectively. A comparison of these results with electrostatic energy profiles for the translocation of a probe cation throughout the water permeation pathway indicates that the free-energy profile for proton movement inside the narrow pore is dominated by static effects arising from the distribution of charged and polar groups of the channel, whereas dielectric effects contribute primarily to opposing the access of H+ to the pore mouths (desolvation penalty). The single most effective way to abolish the free-energy gradients opposing the movement of H+ around the NPA motif is to turn off the dipole moments of helices M3 and M7. Mutation of either of the two NPA Asn residues to Asp compensates for charge-dipole and dipole-dipole effects opposing the hop and turn steps of structural diffusion, respectively, and dramatically reduces the free energy barrier of proton translocation, suggesting that these single mutants could

  18. Proton-dependent multidrug efflux systems.

    PubMed Central

    Paulsen, I T; Brown, M H; Skurray, R A

    1996-01-01

    Multidrug efflux systems display the ability to transport a variety of structurally unrelated drugs from a cell and consequently are capable of conferring resistance to a diverse range of chemotherapeutic agents. This review examines multidrug efflux systems which use the proton motive force to drive drug transport. These proteins are likely to operate as multidrug/proton antiporters and have been identified in both prokaryotes and eukaryotes. Such proton-dependent multidrug efflux proteins belong to three distinct families or superfamilies of transport proteins: the major facilitator superfamily (MFS), the small multidrug resistance (SMR) family, and the resistance/ nodulation/cell division (RND) family. The MFS consists of symporters, antiporters, and uniporters with either 12 or 14 transmembrane-spanning segments (TMS), and we show that within the MFS, three separate families include various multidrug/proton antiport proteins. The SMR family consists of proteins with four TMS, and the multidrug efflux proteins within this family are the smallest known secondary transporters. The RND family consists of 12-TMS transport proteins and includes a number of multidrug efflux proteins with particularly broad substrate specificity. In gram-negative bacteria, some multidrug efflux systems require two auxiliary constituents, which might enable drug transport to occur across both membranes of the cell envelope. These auxiliary constituents belong to the membrane fusion protein and the outer membrane factor families, respectively. This review examines in detail each of the characterized proton-linked multidrug efflux systems. The molecular basis of the broad substrate specificity of these transporters is discussed. The surprisingly wide distribution of multidrug efflux systems and their multiplicity in single organisms, with Escherichia coli, for instance, possessing at least nine proton-dependent multidrug efflux systems with overlapping specificities, is examined. We also

  19. Blackbody Infrared Radiative Dissociation of Protonated Oligosaccharides

    NASA Astrophysics Data System (ADS)

    Fentabil, Messele A.; Daneshfar, Rambod; Kitova, Elena N.; Klassen, John S.

    2011-12-01

    The dissociation pathways, kinetics, and energetics of protonated oligosaccharides in the gas phase were investigated using blackbody infrared radiative dissociation (BIRD). Time-resolved BIRD measurements were performed on singly protonated ions of cellohexaose (Cel6), which is composed of β-(1 → 4)-linked glucopyranose rings, and five malto-oligosaccharides (Malx, where x = 4-8), which are composed of α-(1 → 4)-linked glucopyranose units. At the temperatures investigated (85-160 °C), the oligosaccharides dissociate at the glycosidic linkages or by the loss of a water molecule to produce B- or Y-type ions. The Y ions dissociate to smaller Y or B ions, while the B ions yield exclusively smaller B ions. The sequential loss of water molecules from the smallest B ions (B1 and B2) also occurs. Rate constants for dissociation of the protonated oligosaccharides and the corresponding Arrhenius activation parameters (Ea and A) were determined. The Ea and A-factors measured for protonated Malx (x > 4) are indistinguishable within error (~19 kcal mol-1, 1010 s-1), which is consistent with the ions being in the rapid energy exchange limit. In contrast, the Arrhenius parameters for protonated Cel6 (24 kcal mol-1, 1012 s-1) are significantly larger. These results indicate that both the energy and entropy changes associated with the glycosidic bond cleavage are sensitive to the anomeric configuration. Based on the results of this study, it is proposed that formation of B and Y ions occurs through a common dissociation mechanism, with the position of the proton establishing whether a B or Y ion is formed upon glycosidic bond cleavage.

  20. Quantum dynamics in continuum for proton transport II: Variational solvent-solute interface.

    PubMed

    Chen, Duan; Chen, Zhan; Wei, Guo-Wei

    2012-01-01

    Proton transport plays an important role in biological energy transduction and sensory systems. Therefore, it has attracted much attention in biological science and biomedical engineering in the past few decades. The present work proposes a multiscale/multiphysics model for the understanding of the molecular mechanism of proton transport in transmembrane proteins involving continuum, atomic, and quantum descriptions, assisted with the evolution, formation, and visualization of membrane channel surfaces. We describe proton dynamics quantum mechanically via a new density functional theory based on the Boltzmann statistics, while implicitly model numerous solvent molecules as a dielectric continuum to reduce the number of degrees of freedom. The density of all other ions in the solvent is assumed to obey the Boltzmann distribution in a dynamic manner. The impact of protein molecular structure and its charge polarization on the proton transport is considered explicitly at the atomic scale. A variational solute-solvent interface is designed to separate the explicit molecule and implicit solvent regions. We formulate a total free-energy functional to put proton kinetic and potential energies, the free energy of all other ions, and the polar and nonpolar energies of the whole system on an equal footing. The variational principle is employed to derive coupled governing equations for the proton transport system. Generalized Laplace-Beltrami equation, generalized Poisson-Boltzmann equation, and generalized Kohn-Sham equation are obtained from the present variational framework. The variational solvent-solute interface is generated and visualized to facilitate the multiscale discrete/continuum/quantum descriptions. Theoretical formulations for the proton density and conductance are constructed based on fundamental laws of physics. A number of mathematical algorithms, including the Dirichlet-to-Neumann mapping, matched interface and boundary method, Gummel iteration, and Krylov