Science.gov

Sample records for beam lifetime studies

  1. The radiation measurement applied to beam lifetime study on the synchrotron radiation facilities

    NASA Astrophysics Data System (ADS)

    Li, Yuxiong; Li, Juexin; Liu, Zuping; Cui, Yonggang; Gong, Guanghua; Shao, Beibei

    2003-06-01

    To collect beam loss information from an accelerator radiation field is helpful to machine study and operation. For a synchrotron radiation storage ring, shower electrons give a distinct clue to loss location and a BLM-XS model detector is suitable to detect them. Recently, we set up a new beam loss monitoring system by this method for National Synchrotron Radiation Laboratory (NSRL) storage ring. It does not interfere with the vacuum chamber and machine operation. Different from other systems, the detectors are used in pairs, fixed on opposite sides of the chamber separately. Some interesting phenomena about beam lifetime were observed. We located exactly where an excessive beam loss took place during ramping process and solved the problem. It was proved that gas accumulated at the front ends of photo-beam lines strongly impacted the electron beam and led to beam lifetime decreases. The cause of beam lifetime decrease because of superconducting wiggler is discussed.

  2. High energy beam lifetime analysis

    SciTech Connect

    Howell, R.H.; Sterne, P.A.; Hartley, J.; Cowan, T.E.

    1997-05-01

    We have developed a positron lifetime defect analysis capability based on a 3 MeV electrostatic accelerator. The high energy beam lifetime spectrometer is operational with a 60 mCi {sup 22}Na source providing a current of 7 10{sup 5} positrons per second. Lifetime data are derived from a thin plastic transmission detector providing an implantation time and a BaF{sub 2} detector to determine the annihilation time. Positron lifetime analysis is performed with a 3 MeV positron beam on thick sample specimens at counting rates in excess of 2000 per second. The instrument is being used for bulk sample analysis and analysis of samples encapsulated in controlled environments for in situ measurements.

  3. The TRIple PLunger for EXotic beams TRIPLEX for excited-state lifetime measurement studies on rare isotopes

    NASA Astrophysics Data System (ADS)

    Iwasaki, H.; Dewald, A.; Braunroth, T.; Fransen, C.; Smalley, D.; Lemasson, A.; Morse, C.; Whitmore, K.; Loelius, C.

    2016-01-01

    A new device, the TRIple PLunger for EXotic beams (TRIPLEX), has been developed for lifetime measurement studies with rare isotope beams. This plunger device holds up to three metal foils in the beam path and facilitates the recoil distance Doppler-shift technique to measure lifetimes of nuclear excited states in the range of 1 ps to 1 ns. The unique design allows independent movement of the target and the second degrader with respect to a fixed first degrader in between, enabling advanced experimental approaches, such as the differential recoil distance method and the double recoil distance method. The design and control of the device are presented in this paper, together with simulated performances of the new applications. As an example of actual experiments, results from the lifetime measurement of the neutron-rich 17C isotope performed at the National Superconducting Cyclotron Laboratory are shown.

  4. 6-D weak-strong beam-beam simulation study of proton lifetime in presence of head-on beam-beam compensation in the RHIC

    SciTech Connect

    Luo, Y.; Fischer, W.

    2010-08-01

    In this note we summarize the calculated particle loss of a proton bunch in the presence of head-on beam-beam compensation in the Relativistic Heavy Ion Collider (RHIC). To compensate the head-on beam-beam effect in the RHIC 250 GeV polarized proton run, we are introducing a DC electron beam with the same transverse profile as the proton beam to collide with the proton beam. Such a device is called an electron lens (e-lens). In this note we first present the optics and beam parameters and the tracking setup. Then we calculate and compare the particle loss of a proton bunch with head-on beam-beam compensation, phase advance of k{pi} between IP8 and the center of the e-lens and second order chromaticity correction. We scanned the proton beam's linear chromaticity, working point and bunch intensity. We also scanned the electron beam's intensity, transverse beam size. The effect of the electron-proton transverse offset in the e-lens was studied. In the study 6-D weak-strong beam-beam interaction model a la Hirata is used for proton collisions at IP6 and IP8. The e-lens is modeled as 8 slices. Each slice is modeled with as drift - (4D beam-beam kick) - drift.

  5. Measurement of Beam Lifetime and Applications for SPEAR3

    SciTech Connect

    Huang, Xiaobiao; Corbett, Jeff; /SLAC

    2011-04-05

    Beam lifetime studies for the SPEAR3 storage ring are presented. The three lifetime components are separated with lifetime measurements under various combinations of beam currents and fill patterns and vertical scraper scans. Touschek lifetime is studied with rf voltage scans and with the horizontal or vertical scrapers inserted. The measurements are explained with calculations based on the calibrated lattice model. Quantum lifetime measurements are performed with reduced longitudinal and horizontal apertures, respectively, from which we deduce the radiation energy loss down to a few keV per revolution and the horizontal beam size.

  6. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring

    SciTech Connect

    Kumar, Pradeep; Ghodke, A. D.; Karnewar, A. K.; Holikatti, A. C.; Yadav, S.; Puntambekar, T. A.; Singh, G.; Singh, P.

    2013-12-15

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  7. Measurements of aperture and beam lifetime using movable beam scrapers in Indus-2 electron storage ring.

    PubMed

    Kumar, Pradeep; Ghodke, A D; Karnewar, A K; Holikatti, A C; Yadav, S; Puntambekar, T A; Singh, G; Singh, P

    2013-12-01

    In this paper, the measurements of vertical and horizontal aperture which are available for stable beam motion in Indus-2 at beam energy 2.5 GeV using movable beam scrapers are presented. These beam scrapers are installed in one of the long straight sections in the ring. With the movement of beam scrapers towards the beam centre, the beam lifetime is measured. The beam lifetime data obtained from the movement of vertical and horizontal beam scrapers are analyzed. The contribution of beam loss due to beam-gas scattering (vacuum lifetime) and electron-electron scattering within a beam bunch (Touschek lifetime) is separated from the measured beam lifetime at different positions of the beam scrapers. Vertical and horizontal beam sizes at scrapers location are estimated from the scraper movement towards the beam centre in quantum lifetime limit and their values closely agree with measured value obtained using X-ray diagnostic beamline.

  8. BEAM LIFETIME AND EMITTANCE GROWTH MEASUREMENTS OF GOLD BEAMS IN RHIC AT STORAGE.

    SciTech Connect

    FISCHER,W.; DREES,A.; BRENNAN,J.M.; CONNOLLY,R.; FLILLER,R.; TEPIKIAN,S.; VAN ZEIJTS,J.

    2001-06-18

    During stores of gold beams, longitudinal and transverse beam sizes were recorded. Longitudinal profiles were obtained with a wall current monitor. Transverse profiles were reconstructed from gold-gold collision rates at various relative transverse beam positions. The total beam lifetime was measured with a beam current transformer, the bunched beam lifetime with the wall current monitor. Diffusion rates in the beam halo were determined from the change in the loss rate when a scraper is retracted. The measurements are used to determine the lifetime limiting effects. Beam growth measurements are compared with computations of beam-growth times from intra-beam scattering.

  9. Beam lifetime and limitations during low-energy RHIC operation

    SciTech Connect

    Fedotov, A.V.; Bai, M.; Blaskiewicz, M.; Fischer, W.; Kayran, D.; Montag, C.; Satogata, T.; Tepikian, S.; Wang, G.

    2011-03-28

    The low-energy physics program at the Relativistic Heavy Ion Collider (RHIC), motivated by a search for the QCD phase transition critical point, requires operation at low energies. At these energies, large nonlinear magnetic field errors and large beam sizes produce low beam lifetimes. A variety of beam dynamics effects such as Intrabeam Scattering (IBS), space charge and beam-beam forces also contribute. All these effects are important to understand beam lifetime limitations in RHIC at low energies. During the low-energy RHIC physics run in May-June 2010 at beam {gamma} = 6.1 and {gamma} = 4.1, gold beam lifetimes were measured for various values of space-charge tune shifts, transverse acceptance limitation by collimators, synchrotron tunes and RF voltage. This paper summarizes our observations and initial findings.

  10. Experimental demonstration of colliding beam lifetime improvement by electron lenses

    SciTech Connect

    Shiltsev, Vladimir; Alexahin, Yuri; Kamerdzhiev, Vsevolod; Kuznetsov, Gennady; Zhang, Xiao-Long; Bishofberger, Kip; /Los Alamos

    2007-10-01

    We report successful application of space-charge forces of a low-energy electron beam for improvement of particle lifetime determined by beam-beam interaction in high-energy collider. In our experiments, an electron lens, a novel instrument developed for the beam-beam compensation, was set on a 980-GeV proton bunch in the Tevatron proton-antiproton collider. The proton bunch losses due to its interaction with antiproton beam were reduced by a factor of 2 when the electron lens was operating. We describe the principle of electron lens operation and present experimental results.

  11. Long beam-lifetime operation at the SORTEC SR ring

    SciTech Connect

    Awaji, N.; Kodaira, M.; Kishimoto, T.; Usami, H.; Ohno, M.; Tsuchidate, H.; Iida, T.; Tomimasu, T. )

    1992-01-01

    With successful conditioning, the beam lifetime of the SORTEC SR ring extended over 50 h at our nominal beam current of 200 mA. The conditioning and the results are discussed from the point of (i) optimization of operating point, (ii) high vacuum, and (iii) effective removal of the produced ion.

  12. Electron Beam Lifetime in SPEAR3: Measurement and Simulation

    SciTech Connect

    Corbett, J.; Huang, X.; Lee, M.; Lui, P.; Sayyar-Rodsari, B.; /Pavilon Tech., Austin

    2007-12-19

    In this paper we report on electron beam lifetime measurements as a function of scraper position, RF voltage and bunch fill pattern in SPEAR3. We then outline development of an empirical, macroscopic model using the beam-loss rate equation. By identifying the dependence of loss coefficients on accelerator and beam parameters, a numerically-integrating simulator can be constructed to compute beam decay with time. In a companion paper, the simulator is used to train a parametric, non-linear dynamics model for the system [1].

  13. Positron lifetime spectrometer using a DC positron beam

    DOEpatents

    Xu, Jun; Moxom, Jeremy

    2003-10-21

    An entrance grid is positioned in the incident beam path of a DC beam positron lifetime spectrometer. The electrical potential difference between the sample and the entrance grid provides simultaneous acceleration of both the primary positrons and the secondary electrons. The result is a reduction in the time spread induced by the energy distribution of the secondary electrons. In addition, the sample, sample holder, entrance grid, and entrance face of the multichannel plate electron detector assembly are made parallel to each other, and are arranged at a tilt angle to the axis of the positron beam to effectively separate the path of the secondary electrons from the path of the incident positrons.

  14. Bessel beam fluorescence lifetime tomography of live embryos (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Xu, Dongli; Peng, Leilei

    2016-03-01

    Optical tomography allows isotropic 3D imaging of embryos. Scanning-laser optical tomography (SLOT) has superior light collecting efficiency than wide-field optical tomography, making it ideal for fluorescence imaging of live embryos. We previously reported an imaging system that combines SLOT with a novel Fourier-multiplexed fluorescence lifetime imaging (FmFLIM) technique named FmFLIM-SLOT. FmFLIM-SLOT performs multiplexed FLIM-FRET readout of multiple FRET sensors in live embryos. Here we report a recent effort on improving the spatial resolution of the FmFLIM-SLOT system in order to image complex biochemical processes in live embryos at the cellular level. Optical tomography has to compromise between resolution and the depth of view. In SLOT, the commonly-used focused Gaussian beam diverges quickly from the focal plane, making it impossible to achieve high resolution imaging in a large volume specimen. We thus introduce Bessel beam laser-scanning tomography, which illuminates the sample with a spatial-light-modulator-generated Bessel beam that has an extended focal depth. The Bessel beam is scanned across the whole specimen. Fluorescence projection images are acquired at equal angular intervals as the sample rotates. Reconstruction artifacts due to annular-rings of the Bessel beam are removed by a modified 3D filtered back projection algorithm. Furthermore, in combination of Fourier-multiplexing fluorescence lifetime imaging (FmFLIM) method, the Bessel FmFLIM-SLOT system is capable of perform 3D lifetime imaging of live embryos at cellular resolution. The system is applied to in-vivo imaging of transgenic Zebrafish embryos. Results prove that Bessel FmFLIM-SLOT is a promising imaging method in development biology research.

  15. Preservation of beam loss induced quenches, beam lifetime and beam loss measurements with the HERAp beam-loss-monitor system

    NASA Astrophysics Data System (ADS)

    Wittenburg, Kay

    1994-06-01

    The beam-loss-monitors (BLMs) in the HERA-proton-ring (HERAp) must fulfill the following requirements: They have to measure losses sensitive and fast enough to prevent the superconducting magnets from beam loss induced quenching; the dynamic range of the monitors must exceed several decades in order to measure losses during beam lifetimes of hundreds of hours as well as the much stronger losses that may quench superconducting magnets; they have to be insensitive to the synchrotron radiation of the adjacent electron-ring (HERAe); and their radiation hardness must allow a monitor-lifetime of a few years of HERA operation. These requirements are well satisfied by the HERAp-BLM-System.

  16. Mapping of minority carrier lifetime distributions in multicrystalline silicon using transient electron-beam-induced current.

    PubMed

    Kushida, Takuya; Tanaka, Shigeyasu; Morita, Chiaki; Tanji, Takayoshi; Ohshita, Yoshio

    2012-01-01

    We have used transient electron-beam-induced current (EBIC) to map minority carrier lifetime distributions in multicrystalline Silicon (mc-Si). In this technique, the electron beam from a scanning transmission electron microscope was on-off modulated while the sample was scanned. The resulting transient EBIC was analyzed to form a lifetime map. An analytical function was introduced as part of the analysis in determining this map. We have verified this approach using numerical simulations and have reproduced a lifetime map for an mc-Si wafer.

  17. Minority carrier lifetime in iodine-doped molecular beam epitaxy-grown HgCdTe

    SciTech Connect

    Madni, I.; Umana-Membreno, G. A.; Lei, W.; Gu, R.; Antoszewski, J.; Faraone, L.

    2015-11-02

    The minority carrier lifetime in molecular beam epitaxy grown layers of iodine-doped Hg{sub 1−x}Cd{sub x}Te (x ∼ 0.3) on CdZnTe substrates has been studied. The samples demonstrated extrinsic donor behavior for carrier concentrations in the range from 2 × 10{sup 16} cm{sup −3} to 6 × 10{sup 17} cm{sup −3} without any post-growth annealing. At a temperature of 77 K, the electron mobility was found to vary from 10{sup 4} cm{sup 2}/V s to 7 × 10{sup 3} cm{sup 2}/V s and minority carrier lifetime from 1.6 μs to 790 ns, respectively, as the carrier concentration was increased from 2 × 10{sup 16} cm{sup −3} to 6 × 10{sup 17} cm{sup −3}. The diffusion of iodine is much lower than that of indium and hence a better alternative in heterostructures such as nBn devices. The influence of carrier concentration and temperature on the minority carrier lifetime was studied in order to characterize the carrier recombination mechanisms. Measured lifetimes were also analyzed and compared with the theoretical models of the various recombination processes occurring in these materials, indicating that Auger-1 recombination was predominant at higher doping levels. An increase in deep-level generation-recombination centers was observed with increasing doping level, which suggests that the increase in deep-level trap density is associated with the incorporation of higher concentrations of iodine into the HgCdTe.

  18. Lifetime measurements in an electrostatic ion beam trap using image charge monitoring

    SciTech Connect

    Rahinov, Igor; Toker, Yoni; Heber, Oded; Rappaport, Michael; Zajfman, Daniel; Strasser, Daniel; Schwalm, Dirk

    2012-03-15

    A technique for mass-selective lifetime measurements of keV ions in a linear electrostatic ion beam trap is presented. The technique is based on bunching the ions using a weak RF potential and non-destructive ion detection by a pick-up electrode. This method has no mass-limitation, possesses the advantage of inherent mass-selectivity, and offers a possibility of measuring simultaneously the lifetimes of different ion species with no need for prior mass-selection.

  19. RHIC PROTON BEAM LIFETIME INCREASE WITH 10- AND 12-POLE CORRECTORS

    SciTech Connect

    Fischer, W.

    2010-05-23

    The RHIC beam lifetime in polarized proton operation is dominated by the beam-beam effect, parameter modulations, and nonlinear magnet errors in the interaction region magnets. Sextupole and skew sextupole errors have been corrected deterministically for a number of years based on tune shift measurements with orbit bumps in the triplets. During the most recent polarized proton run 10- and 12- pole correctors were set through an iterative procedure, and used for the first time operationally in one of the beams. We report on the procedure to set these high-order multipole correctors and estimate their effect on the integrated luminosity.

  20. Precision lifetime measurements of N ii levels with the beam-foil-laser method

    NASA Astrophysics Data System (ADS)

    Baudinet-Robinet, Y.; Garnir, H.-P.; Dumont, P.-D.; Résimont, J.

    1990-08-01

    Precision lifetime measurements using laser excitation of a fast ion beam preexcited in a carbon foil are reported for two levels in N ii. The cascade-free decays of the fluorescence intensities give lifetimes of 0.249+/-0.004 and 0.267+/-0.010 ns for the N ii 2p3d 1F° and 2p3s 1P° levels, respectively. The lifetime result for the 2p3d 1F° level-which is weakly repopulated by long-lived cascades-is in good agreement with beam-foil values and with the theoretical lifetime of McEachran and Cohen [J. Quant. Spectrosc. Radiat. Transfer 27, 119 (1982)]. The lifetime result for the 2p3s 1P ° level-which is strongly repopulated by cascades-differs significantly from most of the previous experimental values but is in good agreement with the theoretical lifetimes of Luken and Sinanoglu [J. Chem. Phys. 64, 3141 (1976)], Beck and Nicolaides [Phys. Lett. 56A, 265 (1976)], McEachran and Cohen, and Fawcett [At. Data Nucl. Data Tables 37, 411 (1987)]. The f-value trend for the 2p2 1D-2p3s 1P° transition along the C i sequence is discussed.

  1. Plunger lifetime measurements after Coulomb excitation at intermediate beam energies

    SciTech Connect

    Dewald, A.; Hackstein, M.; Rother, W.; Jolie, J.; Melon, B.; Pissulla, T.; Shimbara, Y.; Starosta, K.; Adrich, P.; Amthor, A. M.; Baumann, T.; Bazin, D.; Bowen, M.; Chester, A.; Dunomes, A.; Gade, A.; Galaviz, D.; Glasmacher, T.; Ginter, T.; Hausmann, M.

    2009-01-28

    Absolute transition probabilities of the first 2{sup +} state in {sup 110,114}Pd were remeasured using the recoil distance Doppler shift technique following projectile Coulomb excitation at intermediate beam energies for the first time. The {sup 110}Pd experiment served to check the novel technique as well as the method used for the data analysis which is based on the examination of {gamma}-ray lineshapes. Whereas the measured B(E2) value for {sup 110}Pd agrees very well with the literature, the value obtained for {sup 114}Pd differs considerably. The data is also used to test a novel concept, called the valence proton symmetry, which allows one to extrapolate nuclear properties to very neutron rich nuclei.

  2. Measuring the free neutron lifetime to <= 0.3s via the beam method

    NASA Astrophysics Data System (ADS)

    Mulholland, Jonathan; Fomin, Nadia; BL3 Collaboration

    2015-10-01

    Neutron beta decay is an archetype for all semi-leptonic charged-current weak processes. A precise value for the neutron lifetime is required for consistency tests of the Standard Model and is needed to predict the primordial 4He abundance from the theory of Big Bang Nucleosynthesis. An effort has begun for an in-beam measurement of the neutron lifetime with an projected <=0.3s uncertainty. This effort is part of a phased campaign of neutron lifetime measurements based at the NIST Center for Neutron Research, using the Sussex-ILL-NIST technique. Recent advances in neutron fluence measurement techniques as well as new large area silicon detector technology address the two largest sources of uncertainty of in-beam measurements, paving the way for a new measurement. The experimental design and projected uncertainties for the 0.3s measurement will be discussed.

  3. Measuring the free neutron lifetime to <= 0.3s via the beam method

    NASA Astrophysics Data System (ADS)

    Fomin, Nadia; Mulholland, Jonathan

    2015-04-01

    Neutron beta decay is an archetype for all semi-leptonic charged-current weak processes. A precise value for the neutron lifetime is required for consistency tests of the Standard Model and is needed to predict the primordial 4 He abundance from the theory of Big Bang Nucleosynthesis. An effort has begun for an in-beam measurement of the neutron lifetime with an projected <=0.3s uncertainty. This effort is part of a phased campaign of neutron lifetime measurements based at the NIST Center for Neutron Research, using the Sussex-ILL-NIST technique. Recent advances in neutron fluence measurement techniques as well as new large area silicon detector technology address the two largest sources of uncertainty of in-beam measurements, paving the way for a new measurement. The experimental design and projected uncertainties for the 0.3s measurement will be discussed. This work is supported by the DOE office of Science, NIST and NSF.

  4. CONSTRAINTS ON QUASAR LIFETIMES AND BEAMING FROM THE He II Ly{alpha} FOREST

    SciTech Connect

    Furlanetto, Steven R.; Lidz, Adam

    2011-07-10

    We show that comparisons of He II Ly{alpha} forest lines of sight to nearby quasar populations can strongly constrain the lifetimes and emission geometry of quasars. By comparing the He II and H I Ly{alpha} forests along a particular line of sight, one can trace fluctuations in the hardness of the radiation field (which are driven by fluctuations in the He II ionization rate). Because this high-energy background is highly variable-thanks to the rarity of the bright quasars that dominate it and the relatively short attenuation lengths of these photons-it is straightforward to associate features in the radiation field with their source quasars. Here we quantify how finite lifetimes and beamed emission geometries affect these expectations. Finite lifetimes induce a time delay that displaces the observed radiation peak relative to the quasar. For beamed emission, geometry dictates that sources invisible to the observer can still create a peak in the radiation field. We show that both these models produce substantial populations of 'bare' peaks (without an associated quasar) for reasonable parameter values (lifetimes {approx}10{sup 6}-10{sup 8} yr and beaming angles {approx}< 90 deg.). A comparison to existing quasar surveys along two He II Ly{alpha} forest lines of sight rules out isotropic emission and infinite lifetime at high confidence; they can be accommodated either by moderate beaming or lifetimes {approx}10{sup 7}-10{sup 8} yr. We also show that the distribution of radial displacements between peaks and their quasars can unambiguously distinguish these two models, although larger statistical samples are needed.

  5. A satellite mortality study to support space systems lifetime prediction

    NASA Astrophysics Data System (ADS)

    Fox, George; Salazar, Ronald; Habib-Agahi, Hamid; Dubos, Gregory F.

    Estimating the operational lifetime of satellites and spacecraft is a complex process. Operational lifetime can differ from mission design lifetime for a variety of reasons. Unexpected mortality can occur due to human errors in design and fabrication, to human errors in launch and operations, to random anomalies of hardware and software or even satellite function degradation or technology change, leading to unrealized economic or mission return. This study focuses on data collection of public information using, for the first time, a large, publically available dataset, and preliminary analysis of satellite lifetimes, both operational lifetime and design lifetime. The objective of this study is the illustration of the relationship of design life to actual lifetime for some representative classes of satellites and spacecraft. First, a Weibull and Exponential lifetime analysis comparison is performed on the ratio of mission operating lifetime to design life, accounting for terminated and ongoing missions. Next a Kaplan-Meier survivor function, standard practice for clinical trials analysis, is estimated from operating lifetime. Bootstrap resampling is used to provide uncertainty estimates of selected survival probabilities. This study highlights the need for more detailed databases and engineering reliability models of satellite lifetime that include satellite systems and subsystems, operations procedures and environmental characteristics to support the design of complex, multi-generation, long-lived space systems in Earth orbit.

  6. A Satellite Mortality Study to Support Space Systems Lifetime Prediction

    NASA Technical Reports Server (NTRS)

    Fox, George; Salazar, Ronald; Habib-Agahi, Hamid; Dubos, Gregory

    2013-01-01

    Estimating the operational lifetime of satellites and spacecraft is a complex process. Operational lifetime can differ from mission design lifetime for a variety of reasons. Unexpected mortality can occur due to human errors in design and fabrication, to human errors in launch and operations, to random anomalies of hardware and software or even satellite function degradation or technology change, leading to unrealized economic or mission return. This study focuses on data collection of public information using, for the first time, a large, publically available dataset, and preliminary analysis of satellite lifetimes, both operational lifetime and design lifetime. The objective of this study is the illustration of the relationship of design life to actual lifetime for some representative classes of satellites and spacecraft. First, a Weibull and Exponential lifetime analysis comparison is performed on the ratio of mission operating lifetime to design life, accounting for terminated and ongoing missions. Next a Kaplan-Meier survivor function, standard practice for clinical trials analysis, is estimated from operating lifetime. Bootstrap resampling is used to provide uncertainty estimates of selected survival probabilities. This study highlights the need for more detailed databases and engineering reliability models of satellite lifetime that include satellite systems and subsystems, operations procedures and environmental characteristics to support the design of complex, multi-generation, long-lived space systems in Earth orbit.

  7. Experimental Studies of Compensation of Beam-Beam Effects with Tevatron Electron Lenses

    SciTech Connect

    Shiltsev, V.; Alexahin, Yu.; Bishofberger, Kip; Kamerdzhiev, V.; Parkhomchuk, V.; Reva, V.; Solyak, N.; Wildman, D.; Zhang, X.-L.; Zimmermann, F.; /Fermilab /Los Alamos /Novosibirsk, IYF /CERN

    2008-02-01

    Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a high-energy collider [1]. In this article we present the results of various beam experiments with 'electron lenses', novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980-GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position; we explore the effects of electron-beam imperfections and noises; and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron Electron Lenses.

  8. Experimental studies of compensation of beam beam effects with Tevatron electron lenses

    NASA Astrophysics Data System (ADS)

    Shiltsev, V.; Alexahin, Y.; Bishofberger, K.; Kamerdzhiev, V.; Parkhomchuk, V.; Reva, V.; Solyak, N.; Wildman, D.; Zhang, X.-L.; Zimmermann, F.

    2008-04-01

    Applying the space-charge forces of a low-energy electron beam can lead to a significant improvement of the beam-particle lifetime limit arising from the beam-beam interaction in a high-energy collider [1]. In this paper, we present the results of various beam experiments with 'electron lenses', novel instruments developed for the beam-beam compensation at the Tevatron, which collides 980 GeV proton and antiproton beams. We study the dependencies of the particle betatron tunes on the electron beam current, energy and position; we explore the effects of electron-beam imperfections and noises; and we quantify the improvements of the high-energy beam intensity and the collider luminosity lifetime obtained by the action of the Tevatron electron lenses.

  9. Observations on the luminosity lifetimes, emittance growth rates and intra-beam scattering at the Tevatron

    SciTech Connect

    Paul L.G. Lebrun et al.

    2003-05-22

    A record luminosity of 4.2 10{sup 31}has been reached at the Fermilab p-{bar p} collider. The lifetime of this luminosity at the beginning of the store is about 10 hours. This lifetime can be explained by the measured loss of anti-protons and protons due to collisions and emittance growths. We report on transverse emittance growth rates based on our Synchrotron Light Monitor. Longitudinal emittance growth rate measurements are based on the TeV Sampled Bunch Display data. It is shown that Intra Beam Scattering is a significant source of emittance growth rates. We comment on other possible factors for these observed emittance growth rates. Finally, we comment on future luminosity lifetimes, as we hope to further increase our peak luminosity.

  10. Feasibility study for long lifetime helium dewar

    NASA Technical Reports Server (NTRS)

    Parmley, R. T.

    1981-01-01

    A feasible concept for a launchable three year lifetime helium dewar was investigted. Current helium dewar designs were examined to see where the largest potential reductions in parasitic heat loads can be made. The study was also devoted to examining support concepts. The support concept chosen, a passive orbital disconnect strut (PODS), has an orbital support conductance that is lower by more than an order of magnitude over current tension band supports. This lower support conductance cuts the total dewar weight in half for the same three year life time requirements. Effort was also concentrated on efficient wire feed through designs and vapor cooling of the multilayer insulation, supports, wire feed throughs and plumbing penetrations. A single stage helium dewar vs. dual stage dewars with a guard cryogen of nitrogen or neon was examined. The single stage dewar concept was selected. Different support concepts were analyzed from which the PODS support concepts was chosen. A preliminary design of the dewar was thermally and structurally analyzed and laid out including system weights, thermal performance and performance sensitivities.

  11. Enhancement of minority carrier lifetime of GaInP with lateral composition modulation structure grown by molecular beam epitaxy

    SciTech Connect

    Park, K. W.; Ravindran, Sooraj; Kang, S. J.; Hwang, H. Y.; Jho, Y. D.; Park, C. Y.; Jo, Y. R.; Kim, B. J.; Lee, Y. T.

    2014-07-28

    We report the enhancement of the minority carrier lifetime of GaInP with a lateral composition modulated (LCM) structure grown using molecular beam epitaxy (MBE). The structural and optical properties of the grown samples are studied by transmission electron microscopy and photoluminescence, which reveal the formation of vertically aligned bright and dark slabs corresponding to Ga-rich and In-rich GaInP regions, respectively, with good crystal quality. With the decrease of V/III ratio during LCM GaInP growth, it is seen that the band gap of LCM GaInP is reduced, while the PL intensity remains high and is comparable to that of bulk GaInP. We also investigate the minority carrier lifetime of LCM structures made with different flux ratios. It is found that the minority carrier lifetime of LCM GaInP is ∼37 times larger than that of bulk GaInP material, due to the spatial separation of electrons and holes by In-rich and Ga-rich regions of the LCM GaInP, respectively. We further demonstrate that the minority carrier lifetime of the grown LCM GaInP structures can easily be tuned by simply adjusting the V/III flux ratio during MBE growth, providing a simple yet powerful technique to tailor the electrical and optical properties at will. The exceptionally high carrier lifetime and the reduced band gap of LCM GaInP make them a highly attractive candidate for forming the top cell of multi-junction solar cells and can enhance their efficiency, and also make them suitable for other optoelectronics devices, such as photodetectors, where longer carrier lifetime is beneficial.

  12. Beam-laser lifetime measurements for some selected levels in singly ionized thulium

    NASA Astrophysics Data System (ADS)

    Rieger, Georg; McCurdy, Michelle M.; Pinnington, Eric H.

    1999-11-01

    The lifetimes of 16 levels in Tm II have been measured using the fast-beam-laser technique to resolve the disagreement between time-resolved laser-induced fluorescence measurements recently published by Anderson, Den Hartog, and Lawler [J. Opt. Soc. Am. B 13, 2382 (1996)] and a new relativistic Hartree-Fock calculation by Quinet, Palmeri, and Biémont [J. Quant. Spectrosc. Radiat. Transf. 62, 625 (1999)]. In all cases except one, our results support the previous measurement, but with a higher precision.

  13. Simulation study of beam-beam effects in ion beams with large space charge tuneshift

    SciTech Connect

    Montag C.

    2012-05-20

    During low-energy operations with gold-gold collisions at 3.85 GeV beam energy, significant beam lifetime reductions have been observed due to the beam-beam interaction in the presence of large space charge tuneshifts. These beam-beam tuneshift parameters were about an order of magnitude smaller than during regular high energy operations. To get a better understanding of this effect, simulations have been performed. Recent results are presented.

  14. Study of beam-beam effects in eRHIC

    SciTech Connect

    Hao, Y.; Litvinenko, V.; Ptitsyn, V.

    2010-05-23

    Beam-beam effects in eRHIC have a number of unique features, which distinguish them from both hadron and lepton colliders. Due to beam-beam interaction, both electron and hadron beams would suffer quality degradation or beam loss from without proper treatments. Those features need novel study and dedicate countermeasures. We study the beam dynamics and resulting luminosity of the characteristics, including mismatch, disruption and pinch effects on electron beam, in additional to their consequences on the opposing beam as a wake field and other incoherent effects of hadron beam. We also carry out countermeasures to prevent beam quality degrade and coherent instability.

  15. Positron annihilation lifetime study of radiation-damaged natural zircons

    NASA Astrophysics Data System (ADS)

    Roberts, J.; Gaugliardo, P.; Farnan, I.; Zhang, M.; Vance, E. R.; Davis, J.; Karatchevtseva, I.; Knott, R. B.; Mudie, S.; Buckman, S. J.; Sullivan, J. P.

    2016-04-01

    Zircons are a well-known candidate waste form for actinides and their radiation damage behaviour has been widely studied by a range of techniques. In this study, well-characterised natural single crystal zircons have been studied using Positron Annihilation Lifetime Spectroscopy (PALS). In some, but not all, of the crystals that had incurred at least half of the alpha-event damage of ∼1019 α/g required to render them structurally amorphous, PALS spectra displayed long lifetimes corresponding to voids of ∼0.5 nm in diameter. The long lifetimes corresponded to expectations from published Small-Angle X-ray Scattering data on similar samples. However, the non-observation by PALS of such voids in some of the heavily damaged samples may reflect large size variations among the voids such that no singular size can be distinguished or. Characterisation of a range of samples was also performed using scanning electron microscopy, optical absorption spectroscopy, Raman scattering and X-ray scattering/diffraction, with the degree of alpha damage being inferred mainly from the Raman technique and X-ray diffraction. The observed void diameters and intensities of the long lifetime components were changed somewhat by annealing at 700 °C; annealing at 1200 °C removed the voids entirely. The voids themselves may derive from He gas bubbles or voids created by the inclusion of small quantities of organic and hydrous matter, notwithstanding the observation that no voidage was evidenced by PALS in two samples containing hydrous and organic matter.

  16. Study of Chemical Carcinogens by Positron Annihilation Lifetime Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pivtsaev, A. A.; Razov, V. I.; Karasev, A. O.

    2013-11-01

    We have used positron annihilation lifetime spectroscopy to study the carcinogens C21H20BrN3, C4H7Cl2O4P, CCl4, CHCl3, AlF3, C8H12N4O, C6H4Cl2 and the non-carcinogens H2O, AlCl3, CH2Cl2, C2H6OS. We have established a correlation between the annihilation characteristics of the studied compounds and their degree of carcinogenicity.

  17. Study of Ice Particle Formation and Lifetime in Space Environment

    NASA Technical Reports Server (NTRS)

    Jeng, D.

    1972-01-01

    The ice particles are formed when liquid and/or humid gases vent to the space. These submicroscopic ice particles are potential contamination sources of the environments during Skylab operations. The critical size of ice particle and its nucleation rate based on the theory of homogeneous and heterogeneous nucleation by sublimation are analyzed. The equations which are pertinent for studying the growth and evaporation of the ice particles are formulated. The mechanisms affecting the lifetime of ice particle are discussed. The gas dynamic techniques for experimental study of ice particle formation are proposed.

  18. Touschek Background and Lifetime Studies for the SuperB Factory

    SciTech Connect

    Boscolo, M.; Biagini, M.; Raimondi, P.; Sullivan, M.; Paoloni, E.; /INFN, Pisa

    2010-08-26

    The novel crab waist collision scheme under test at the DA{Phi}NE Frascati {Phi}-factory finds its natural application to the SuperB project, the asymmetric e{sup +}e{sup -} flavour factory at very high luminosity with relatively low beam currents and reduced backgrounds. The SuperB accelerator design requires a careful choice of beam parameters to reach a good trade-off between different effects. We present here simulation results for the Touschek backgrounds and lifetime obtained for both the low and high energy rings for different machine designs. A first set of horizontal collimators has been studied to stop Touschek particles. A study of the distributions of the Touschek particle losses at the interaction region into the detectors for further investigations is underway.

  19. Multiple Myeloma and lifetime occupation: results from the EPILYMPH study

    PubMed Central

    2012-01-01

    Background The EPILYMPH study applied a detailed occupational exposure assessment approach to a large multi-centre case–control study conducted in six European countries. This paper analysed multiple myeloma (MM) risk associated with level of education, and lifetime occupational history and occupational exposures, based on the EPILYMPH data set. Methods 277 MM cases and four matched controls per each case were included. Controls were randomly selected, matching for age (+/− 5 years), centre and gender. Lifetime occupations and lifetime exposure to specific workplace agents was obtained through a detailed questionnaire. Local industrial hygienists assessed likelihood and intensity for specific exposures. The odds ratio and 95% confidence intervals (OR, 95% CI) were calculated for level of education, individual occupations and specific exposures. Unconditional logistic regression models were run for individual occupations and exposures. Results A low level of education was associated with MM OR=1.68 (95% CI 1.02-2.76). An increased risk was observed for general farmers (OR=1.77; 95% CI 1.05-2.99) and cleaning workers (OR=1.69; 95% CI 1.04-2.72) adjusting for level of education. Risk was also elevated, although not significant, for printers (OR=2.06; 95% CI 0.97-4.34). Pesticide exposure over a period of ten years or more increased MM risk (OR=1.62; 95% CI 1.01-2.58). Conclusion These results confirm an association of MM with farm work, and indicate its association with printing and cleaning. While prolonged exposure to pesticides seems to be a risk factor for MM, an excess risk associated with exposure to organic solvents could not be confirmed. PMID:23241100

  20. Source fabrication and lifetime for Li+ ion beams extracted from alumino-silicate sources

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W

    2012-03-05

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm2 have been measured from lithium alumino-silicate ion sources at a temperature of ~1275 °C. At higher extraction voltages, the source appears to become emission limited with J ≥ 1.5 mA/cm2, and J increases weakly with the applied voltage. A 6.35 mm diameter source with an alumino-silicate coating, ≤0.25 mm thick, has a measured lifetime of ~40 h at ~1275 °C, when pulsed at 0.05 Hz and with pulse length of ~6 μs each. At this rate, the source lifetime was independent of the actual beam charge extracted due to the loss of neutral atoms at high temperature. Finally, the source lifetime increases with the amount of alumino-silicate coated on the emitting surface, and may also be further extended if the temperature is reduced between pulses.

  1. Source fabrication and lifetime for Li+ ion beams extracted from alumino-silicate sources

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.

    2012-04-01

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm2 have been measured from lithium alumino-silicate ion sources at a temperature of ~1275 °C. At higher extraction voltages, the source appears to become emission limited with J ≥ 1.5 mA/cm2, and J increases weakly with the applied voltage. A 6.35 mm diameter source with an alumino-silicate coating, ≤0.25 mm thick, has a measured lifetime of ~40 h at ~1275 °C, when pulsed at 0.05 Hz and with pulse length of ~6 μs each. At this rate, the source lifetime was independent of the actual beam charge extracted due to the loss of neutral atoms at high temperature. Finally, the source lifetime increases with the amount of alumino-silicate coated on the emitting surface, and may also be further extended if the temperature is reduced between pulses.

  2. Lifetime of the 1s2s 3S1 metastable level in He-like S14+ measured with an electron beam ion trap

    SciTech Connect

    L?pez-Urrutia, J C; Beiersdorfer, P; Widmann, K

    2006-03-16

    A precision measurement of the lifetime of the lowest exited level of the He-like S{sup 14+} ion carried out at the Livermore EBIT-II electron beam ion trap yielded a value of (703 {+-} 4) ns. Our method extends the range of lifetime measurements accessible with electron beam ion traps into the nanosecond region and improves the accuracy of currently available data for this level by an order of magnitude.

  3. Theoretical study of the K, Rb, and Fr lifetimes

    NASA Astrophysics Data System (ADS)

    Iskrenova Tchoukova, Eugeniya; Safronova, Marianna

    2008-05-01

    We calculate ns, np, and nd lifetimes in K, Rb, and Fr using relativistic high-precision all-order method where all single and double excitations of the Dirac-Hartree-Fock wave function are included to all orders of perturbation theory. Additional calculations are carried out where necessary to account in part for effects of valence triple excitations and to evaluate the uncertainty of the calculations. The data are compared with available experimental values. Our calculations provide benchmark data for a number of E1 matrix elements and branching ratios. We identify lifetimes that are particular useful for tests of high-precision theory owing to extremely large correlations to certain electric-dipole matrix elements. Fr calculations are motivated also by the study of parity nonconservation with this atom [1]. [1] G. Gwinner, E. Gomez, L. A. Orozco, A. Perez Galvan, D. Sheng, Y. Zhao, G. D. Sprouse, J. A. Behr, K. P. Jackson, M. R. Pearson, S. Aubin, and V. V. Flambaum, Hyp. Int. 172 , 45 (2006).

  4. Development of long-lifetime, low-contamination beam dumps for NIF

    SciTech Connect

    Norton, M.A.; Murray, J.E.; Boley, C.D.; Milam, D.; Sell, W.D.; Feit, M.D.; Rubenchik, A.M.

    1996-12-09

    The laser architecture of the NIF beamlines requires small-area beam dumps to safely absorb back reflections from the output and leakage through the PEPC switch. The problems presented by these beam dumps are that fluences they must absorb are very large, beyond the damage threshold of any material, and ablation of beam dump materials potentially contaminates adjacent optical components. Full scale tests have demonstrated that a stainless steel beam dump will survive fluence levels and energies as high as 820 j/CM{sup 2} and 2.5 kJ, respectively. Small scale tests with tungsten, tantalum, and stainless steel have demonstrated erosion rates less than about 0.5 {mu}m/shot, with stainless steel having the smallest rate. They also suggest that increased angles of incidence ({ge}60{degree}) will greatly reduce the material ablated directly back along the beam path.

  5. Fluorescence lifetime-based sensing in tissues: a computational study.

    PubMed Central

    Hutchinson, C L; Lakowicz, J R; Sevick-Muraca, E M

    1995-01-01

    We have numerically solved the photon diffusion equation to predict the distribution of light in a tissue model system with a uniform concentration of fluorophore. Our results show that time-dependent measurements of light propagation can be used to monitor the fluorescent lifetimes of a uniformly distributed fluorophore in tissues. With proper referencing, frequency-domain measurements of phase-shift, theta, may allow quantitation of fluorescent lifetimes, tau, independent of changes in the local absorption and scattering properties. These results point to a new approach for noninvasive diagnostic monitoring through quantitation of fluorescent lifetime, tau, when the lifetime of the fluorophore is comparable with photon migration times. Images FIGURE 1 PMID:7787043

  6. A public study of the lifetime distribution of soap films

    NASA Astrophysics Data System (ADS)

    Tobin, S. T.; Meagher, A. J.; Bulfin, B.; Möbius, M.; Hutzler, S.

    2011-08-01

    We present data for the lifetime distribution of soap films made from commercial dish-washing solution and contained in sealed cylinders. Data for over 2500 films were gathered during a 2-month exhibition on the science and art of bubbles and foams in Dublin's Science Gallery. Visitors to the gallery were invited to create 10-20 parallel soap films in acrylic tubes which were sealed with cork stoppers. Individual film bursts occurred at random and were uncorrelated. The total number of remaining films in the tubes was recorded every day. Visitors could monitor the status of their soap film tube and the daily updated histogram of the lifetime of all films. The histogram of the bubble lifetimes is well described by a Weibull distribution, which indicates that the failure rate is not constant and increases over time. Unsealed cylinders show drastically reduced film lifetimes. This experiment illustrates the difference between the unpredictability of the lifetime of individual films and the existence of a well-defined lifetime distribution for the ensemble.

  7. Merged beams studies for astrobiology

    NASA Astrophysics Data System (ADS)

    Savin, Daniel Wolf; Miller, Kenneth A.; O'Connor, Aodh P.; de Ruette, Nathalie; Stuetzel, Julia; Urbain, Xavier

    2015-05-01

    The chain of chemical reactions leading towards life is thought to begin in molecular clouds when atomic carbon and oxygen react with H3+,leading to the formation of complex organic molecules and of water. Uncertainties in the rate coefficients for these reactions hinder our ability to understand the first links in the chemical chain leading towards life. Theory and experiment have yet to converge in either the magnitude or temperature dependence. We have developed a novel merged beam apparatus to study these reactions at the low collision energies relevant for molecular cloud studies. Photodetachment of atomic anion beams is used to produce beams of neutral C and O, each in their ground term as occurs in molecular clouds. The neutral beam is then merged with a velocity matched, co-propagating H3+beam. The merged beams method allows us to use fast beams (keV in the lab frame), which are easy to handle and monitor, while being able to achieve relative collision energies down to ~ 10 meV. Using the measured merged-beams rate coefficient, we are able to extract cross sections that we can then convolve with a Maxwellian energy spread to generate a thermal rate coefficient for molecular cloud temperatures. Here we report recent results. This work was funded, in part, by the NSF Division of Astronomical Sciences.

  8. Experimental studies of turbulence lifetimes in differentially rotating flows

    NASA Astrophysics Data System (ADS)

    Edlund, E. M.; Yan, Z.; Spence, E. J.; Roach, A. H.; Rhoads, J.; Ji, H.

    2012-11-01

    Inference of accretion rates from observations of stellar systems suggests inward mass fluxes which can only be reasonably explained by a turbulent transport process. While the magneto-rotational instability (MRI) is likely active in systems above a critical ionization, there remains some question as to whether the MRI can be active in cooler bodies such as proto-planetary systems, and if not, what mechanism is then responsible for angular momentum transport? Keplerian rotation profiles are hydrodynamically linearly stable in the inviscid limit, however, it is not known if there exists a subcritical transition. A series of studies in the Hydrodynamic Turbulence Experiment (HTX), a modified Taylor-Couette device, have explored quiescent flows in the quasi-Keplerian regime. Operating in the wide-gap limit and with split axial boundaries to control the Ekman circulation, azimuthal flows in HTX can be brought very close to ideal Couette. These flows are subjected to external perturbations to test their ability to sustain incompressible hydrodynamic turbulence. Under no circumstances has a subcritical transition to turbulence been observed. Turbulence decay lifetimes are measured and compared to theoretical models.

  9. Experimental Studies of beam-beam effects in the Tevatron

    SciTech Connect

    Tanaji Sen et al.

    2003-06-09

    The long-range beam-beam interactions limit the achievable luminosity in the Tevatron. During the past year several studies ere performed on ways of removing the limitations at all stages of the operational cycle. The authors report here on some of these studies, including the effects of changing the helical orbits at injection and collision, tune and chromaticity scans and coupling due to the beam-beam interactions.

  10. Los Alamos National Laboratory W76 Pit Tube Lifetime Study

    SciTech Connect

    Abeln, Terri G.

    2012-04-25

    A metallurgical study was requested as part of the Los Alamos National Laboratory (LANL) W76-1 life-extension program (LEP) involving a lifetime analysis of type 304 stainless steel pit tubes subject to repeat bending loads during assembly and disassembly operations at BWXT/Pantex. This initial test phase was completed during the calendar years of 2004-2006 and the report not issued until additional recommended tests could be performed. These tests have not been funded to this date and therefore this report is considered final. Tubes were reportedly fabricated according to Rocky Flats specification P14548 - Seamless Type 304 VIM/VAR Stainless Steel Tubing. Tube diameter was specified as 0.125 inches and wall thickness as 0.028 inches. A heat treat condition is not specified and the hardness range specification can be characteristic of both 1/8 and 1/4 hard conditions. Properties of all tubes tested were within specification. Metallographic analysis could not conclusively determine a specified limit to number of bends allowable. A statistical analysis suggests a range of 5-7 bends with a 99.95% confidence limit. See the 'Statistical Analysis' section of this report. The initial phase of this study involved two separate sets of test specimens. The first group was part of an investigation originating in the ESA-GTS [now Gas Transfer Systems (W-7) Group]. After the bend cycle test parameters were chosen (all three required bends subjected to the same amount of bend cycles) and the tubes bent, the investigation was transferred to Terri Abeln (Metallurgical Science and Engineering) for analysis. Subsequently, another limited quantity of tubes became available for testing and were cycled with the same bending fixture, but with different test parameters determined by T. Abeln.

  11. Quantifying lifetime exposure to ultraviolet radiation in the epidemiology of cutaneous malignant melanoma: A pilot study

    SciTech Connect

    Lea, C.S.; Selvin, S. . Dept. of Biomedical and Environmental Health Sciences Lawrence Berkeley Lab., CA ); Buffler, P.A. . Dept. of Biomedical and Environmental Health Sciences); Scotto, J. . Biostatistics Branch); Berwick, M. (Cancer Pre

    1992-10-01

    This pilot study uses a unique method to calculate cumulative lifetime exposure to, ultraviolet radiation-b to determine if this refined method would indicate differences in lifetime cumulative UVB exposure between age and sex matched controls. Forty-four age and sex matched cases and controls demonstrated no significant difference in mean cumulative lifetime UVB exposure based on the duration and location of residence. This pilot study suggests that further analysis of the dataset should be conducted to determine if the cumulative lifetime exposure hypothesis is of primary importance regarding the association between UVB exposure and development of cutaneous malignant melanoma.

  12. Vacancy profile in reverse osmosis membranes studied by positron annihilation lifetime measurements and molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Shimazu, A.; Goto, H.; Shintani, T.; Hirose, M.; Suzuki, R.; Kobayashi, Y.

    2013-06-01

    The positron annihilation technique using a slow positron beam can be used for the study of the vacancy profiles in typical reverse osmosis (RO) membranes. In this study, the vacancy profile in the polyamide membrane that exhibits a high permselectivity between ions and water was studied using the positron annihilation technique and molecular dynamics simulations. Ortho-positronium (o-Ps) lifetimes in the surface region of the membranes were evaluated by using a slow positron beam. The diffusion behavior of Na+ and water in the polyamides was simulated by molecular dynamics (MD) methods using the TSUBAME2 supercomputer at the Tokyo Institute of Technology and discussed with the vacancy profile probed by the o-Ps. The results suggested that the large hydration size of Na+ compared to the vacancy size in the polyamides contributes to the increased diffusivity selectivity of water/Na+ that is related to the NaCl desalination performance of the membrane. Both the hydration size of the ions and the vacancy size appeared to be significant parameters to discuss the diffusivity selectivity of water/ions in typical polyamide membranes.

  13. Lifetime increased cancer risk in mice following exposure to clinical proton beam generated neutrons

    PubMed Central

    Gerweck, Leo E.; Huang, Peigen; Lu, Hsiao-Ming; Paganetti, Harald; Zhou, Yenong

    2014-01-01

    Purpose To evaluate the lifespan and risk of cancer following whole-body exposure of mice to neutrons generated by a passively scattered clinical SOBP proton beam. Methods and Materials Three hundred young adult female FVB/N mice, 152 test and 148 control, were entered into the experiment. Mice were placed in an annular cassette around a cylindrical phantom, which was positioned lateral to the mid SOBP of a 165 MeV, clinical proton beam. The average distance from the edge of the mid SOBP to the conscious active mice was 21.5 cm. The phantom was irradiated with once daily fractions of 25 Gy, 4 days per week, for 6 weeks. The age at death and cause of death, i.e., cancer and type vs. non-cancer causes, were assessed over the lifespan of the mice. Results Exposure of mice to a dose of 600 Gy of proton beam generated neutrons, reduced the median lifespan of the mice by 4.2% (Kaplan-Meier cumulative survival, P = 0.053). The relative risk of death from cancer in neutron exposed vs. control mice was 1.40 for cancer of all types (P = 0.0006) and 1.22 for solid cancers (P = 0.09). For a typical 60 Gy dose of clinical protons, the observed 22% increased risk of solid cancer would be expected to decrease by a factor of 10. Conclusions Exposure of mice to neutrons generated by a proton dose which exceeds a typical course of radiotherapy by a factor of 10, resulted in a statistically significant increase in the background incidence of leukemia and a marginally significant increase in solid cancer. The results indicate that the risk of out-of-field 2nd solid cancers from SOBP proton generated neutrons and typical treatment schedules, is 6 - 10 times less than is suggested by current neutron risk estimates. PMID:24725699

  14. Lifetime experimental study of graphite cathode for relativistic backward wave oscillator

    NASA Astrophysics Data System (ADS)

    Wu, Ping; Sun, Jun; Chen, Changhua

    2016-07-01

    Graphite cathodes are widely used due to their good emission properties, especially their long lifetime. Some previous papers have researched their lifetime under certain conditions and uncovered some important phenomena. This paper is dedicated to research the lifetime of the graphite cathode under higher power. In the lifetime test, the voltage and current amplitudes are about 970 kV and 9.7 kA, respectively. The repetition rate is 20 Hz. An X-band relativistic backward wave oscillator is used to generate high power microwave by utilizing the electron beam energy. The experimental results demonstrate that the emission property of the graphite cathode remains quite stable during 105 pulses, despite some slight deteriorations regarding the beam and microwave parameters. The macroscopic morphology change of the cathode blade due to material evaporation is observed by a laser microscope. The mass loss of the graphite cathode is about 60 μg/C. Meanwhile, the observation by a scanning electron microscope uncovers that the original numerous flaky micro-structures are totally replaced by a relatively smooth surface at the mid region of the cathode blade and a large number of new micro-protrusions at the blade edges during the lifetime test.

  15. Merged Beams Studies for Astrobiology

    NASA Astrophysics Data System (ADS)

    Savin, Daniel Wolf; O'Connor, Aodh P.; de Ruette, Nathalie; Miller, Kenneth; Stuetzel, Julia; Urbain, Xavier

    2015-08-01

    The chain of chemical reactions leading towards life is thought to begin in molecular clouds when atomic C and O are fixed into molecules. Reactions of neutral C with H3+ is one of the first steps in the gas-phase chemistry leading to the formation of complex organic molecules. Water, believed to be vital for life, can form via a chain of gas-phase reactions that begin with neutral O reacting with H3+. Uncertainties in the rate coefficient for these reactions hinder our ability to understand the first links in the chemical chain leading towards life. Theory provides little insight as fully quantum mechanical calculations for reactions involving four or more atoms are beyond current capabilities. Experimental data are sparse due to the challenge of producing sufficiently intense and well-characterized beams of neutral atoms.We have developed a novel merged-beam apparatus to study reactions of neutral atoms with molecular ions at the low collision energies relevant for molecular clouds. Photo-detachment of keV-energy atomic anion beams is used to produce beams of neutral C and O. A velocity-matched H3+ beam is then merged with the neutrals. The merged-beams method allows us to achieve kinetic temperatures below 30 K. Using our results, we are able to generate thermal rate coefficients for use in chemical models of molecular clouds.

  16. Merged beam studies for astrobiology

    NASA Astrophysics Data System (ADS)

    De Ruette, Nathalie; Miller, Kenneth A.; O'Connor, Aodh; Stuetzel, Julia; Urbain, Xavier; Savin, Daniel Wolf

    2014-06-01

    The chain of chemical reactions leading towards life is thought to begin in molecular clouds when atomic carbon and oxygen are fixed into molecules. Reactions of neutral atomic C with H3+ is one of the first steps in the gas phase chemistry leading to the formation of complex organic molecules within such clouds. Water, believed to be vital for life, can form via a chain of gas-phase astrochemical reactions that begin with neutral atomic O reacting with H3+. Uncertainties in the thermal rate coefficient for these reactions hinder our ability to understand the first links in the chemical chain leading towards life. Theory and experiment have yet to converge in either the magnitude or temperature dependence. Theory provides little insight as fully quantum mechanical calculations for reactions involving four or more atoms are too complex for current capabilities. On the other hand, measurements of cross sections and rate coefficients for reactions of atoms with molecular ions are extremely challenging. This is due to the difficulty in producing sufficiently intense and well characterized beams of neutral atoms. We have developed a novel merged beam apparatus to study reactions of neutral atoms with molecular ions at the low collision energies relevant for molecular cloud studies. Photodetachment of atomic anion beams, with an 808-nm (1.53-eV) laser beam, is used to produce beams of neutral C and O, each in their ground term as occurs in molecular clouds. The neutral beam is then merged with a velocity matched, co-propagating H3+ beam, in order to study reactions of C and O on H3+. The merged beams method allows us to use fast beams (keV in the lab frame), which are easy to handle and monitor, while being able to achieve relative collision energies down to ≈10 meV. Using the measured merged beams rate coefficient, we are able to extract cross sections which we can then convolve with a Maxwellian energy spread to generate a thermal rate coefficient for molecular cloud

  17. Lifetime studies in H2/Br2 fuel cells

    NASA Astrophysics Data System (ADS)

    Barna, G. G.; Frank, S. N.; Teherani, T. H.; Weedon, L. D.

    1984-09-01

    A fully computerized system has been set up for the life testing of H2 electrodes in 48 percent HBr, and of H2/Br2 fuel cells. Given a fuel cell design with dry H2 and no anolyte loop, the prime parameters influencing the operating lifetime are the hydrophobicity of the anode and the electrolyte transport property of the membrane. A systematic optimization of all the parameters has generated fuel cells that have operated for 10,000h at 2 A/sq in., with no significant degradation.

  18. Studies of beam heating of proton beam profile monitor SEM's

    SciTech Connect

    Pavlovich, Zarko; Osiecki, Thomas H.; Kopp, Sacha E.; /Texas U.

    2005-05-01

    The authors present calculations of the expected temperature rise of proton beam profile monitors due to beam heating. The profile monitors are secondary emission monitors (SEM's) to be made of Titanium foils. The heating is studied to understand whether there is any loss of tension or alignment of such devices. Additionally, calculations of thermally-induced dynamic stress are presented. Ti foil is compared to other materials and also to wire SEM's. The calculations were initially performed for the NuMI beam, where the per-pulse intensity is quite high; for completeness the calculations are also performed for other beam energies and intensities.

  19. Beam Studies with Electron Columns

    SciTech Connect

    Shiltsev, V.; Valishev, A.; Kuznetsov, G.; Kamerdzhiev, V.; Romanov, A.; /Novosibirsk, IYF

    2009-04-01

    We report preliminary results of experimental studies of 'electron columns' in the Tevatron and in a specialized test setup. In the Tevatron, a beam of 150 GeV protons ionizes residual gas and ionization electrons are stored in an electrostatic trap immersed into strong longitudinal magnetic field. Shifts of proton betatron frequencies are observed. In the test setup, we observe effects pointing to accumulation and escape of ionization electrons.

  20. Determination of CdTe bulk carrier lifetime and interface recombination velocity of CdTe/MgCdTe double heterostructures grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Zhao, Xin-Hao; DiNezza, Michael J.; Liu, Shi; Campbell, Calli M.; Zhao, Yuan; Zhang, Yong-Hang

    2014-12-01

    The bulk Shockley-Read-Hall carrier lifetime of CdTe and interface recombination velocity at the CdTe/Mg0.24Cd0.76Te heterointerface are estimated to be around 0.5 μs and (4.7 ± 0.4) × 102 cm/s, respectively, using time-resolved photoluminescence (PL) measurements. Four CdTe/MgCdTe double heterostructures (DHs) with varying CdTe layer thicknesses were grown on nearly lattice-matched InSb (001) substrates using molecular beam epitaxy. The longest lifetime of 179 ns is observed in the DH with a 2 μm thick CdTe layer. It is also shown that the photon recycling effect has a strong influence on the bulk radiative lifetime, and the reabsorption process affects the measured PL spectrum shape and intensity.

  1. Study of defects in electron irradiated CuInSe{sub 2} by positron lifetime spectroscopy

    SciTech Connect

    Polity, A.; Krause-Rehberg, R.; Staab, T.E.; Puska, M.J.; Klais, J.; Moeller, H.J.; Meyer, B.K.

    1998-01-01

    CuInSe{sub 2} was studied in the as-grown state and after low-temperature (4 K) 2 MeV electron irradiation. The positron bulk lifetime of 235 ps was measured for the unirradiated sample. The positron bulk lifetime was theoretically calculated and is in good agreement with the experimental value. In addition, the defect-related lifetimes for mono-, di-, and trivacancies are theoretically determined. An increased average positron lifetime indicated after electron irradiation the appearance of open-volume defects, most probably of divacancy type. The disappearance of this defect was observed during annealing below 250 K. Other defects were formed leading to a divacancy signal at least stable up to 600 K in the temperature range above 450 K. {copyright} {ital 1998 American Institute of Physics.}

  2. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-01-01

    We have studied the properties of a low emittance electron beam produced by laser pulses incident onto an rf gun photocathode. The experiments were carried out at the A0 photoinjector at Fermilab. Such beam studies are necessary for fixing the design of new Linear Colliders as well as for the development of Free Electron Lasers. An overview of the A0 photoinjector is given in Chapter 1. In Chapter 2 we describe the A0 photoinjector laser system. A stable laser system is imperative for reliable photoinjector operation. After the recent upgrade, we have been able to reach a new level of stability in the pulse-to-pulse fluctuations of the pulse amplitude, and of the temporal and transverse profiles. In Chapter 3 we present a study of transverse emittance versus the shape of the photo-cathode drive-laser pulse. For that purpose a special temporal profile laser shaping device called a pulse-stacker was developed. In Chapter 4 we discuss longitudinal beam dynamics studies using a two macro-particle bunch; this technique is helpful in analyzing pulse compression in the magnetic chicane, as well as velocity bunching effects in the rf-gun and the 9-cell accelerating cavity. In Chapter 5 we introduce a proposal for laser acceleration of electrons. We have developed a laser functioning on the TEM*01 mode, a mode with a longitudinal electric field component which is suitable for such a process. Using this technique at energies above 40 MeV, one would be able to observe laser-based acceleration.

  3. The Golden Retriever Lifetime Study: establishing an observational cohort study with translational relevance for human health

    PubMed Central

    Guy, Michael K.; Page, Rodney L.; Jensen, Wayne A.; Olson, Patricia N.; Haworth, J. David; Searfoss, Erin E.; Brown, Diane E.

    2015-01-01

    The Golden Retriever Lifetime Study (GRLS) is the first prospective longitudinal study attempted in veterinary medicine to identify the major dietary, genetic and environmental risk factors for cancer and other important diseases in dogs. The GRLS is an observational study that will follow a cohort of 3000 purebred Golden Retrievers throughout their lives via annual online questionnaires from the dog owner and annual physical examinations and collection of biological samples by the primary care veterinarian. The field of comparative medicine investigating naturally occurring disorders in pets is specifically relevant to the many diseases that have a genetic basis for disease in both animals and humans, including cancer, blindness, metabolic and behavioural disorders and some neurodegenerative disorders. The opportunity for the GRLS to provide high-quality data for translational comparative medical initiatives in several disease categories is great. In particular, the opportunity to develop a lifetime dataset of lifestyle and activity, environmental exposure and diet history combined with simultaneous annual biological sample sets and detailed health outcomes will provide disease incidence data for this cohort of geographically dispersed dogs and associations with a wide variety of potential risk factors. The GRLS will provide a lifetime historical context, repeated biological sample sets and outcomes necessary to interrogate complex associations between genes and environmental influences and cancer. PMID:26056371

  4. The Golden Retriever Lifetime Study: establishing an observational cohort study with translational relevance for human health.

    PubMed

    Guy, Michael K; Page, Rodney L; Jensen, Wayne A; Olson, Patricia N; Haworth, J David; Searfoss, Erin E; Brown, Diane E

    2015-07-19

    The Golden Retriever Lifetime Study (GRLS) is the first prospective longitudinal study attempted in veterinary medicine to identify the major dietary, genetic and environmental risk factors for cancer and other important diseases in dogs. The GRLS is an observational study that will follow a cohort of 3000 purebred Golden Retrievers throughout their lives via annual online questionnaires from the dog owner and annual physical examinations and collection of biological samples by the primary care veterinarian. The field of comparative medicine investigating naturally occurring disorders in pets is specifically relevant to the many diseases that have a genetic basis for disease in both animals and humans, including cancer, blindness, metabolic and behavioural disorders and some neurodegenerative disorders. The opportunity for the GRLS to provide high-quality data for translational comparative medical initiatives in several disease categories is great. In particular, the opportunity to develop a lifetime dataset of lifestyle and activity, environmental exposure and diet history combined with simultaneous annual biological sample sets and detailed health outcomes will provide disease incidence data for this cohort of geographically dispersed dogs and associations with a wide variety of potential risk factors. The GRLS will provide a lifetime historical context, repeated biological sample sets and outcomes necessary to interrogate complex associations between genes and environmental influences and cancer. PMID:26056371

  5. Nutritional intake and dietary patterns in pregnancy: a longitudinal study of women with lifetime eating disorders.

    PubMed

    Micali, Nadia; Northstone, Kate; Emmett, Pauline; Naumann, Ulrike; Treasure, Janet L

    2012-12-14

    There is limited knowledge about dietary patterns and nutrient/food intake during pregnancy in women with lifetime eating disorders (ED). The objective of the present study was to determine patterns of food and nutrient intake in women with lifetime ED as part of an existing longitudinal population-based cohort: the Avon Longitudinal Study of Parents and Children. Women with singleton pregnancies and no lifetime psychiatric disorders other than ED (n 9723) were compared with women who reported lifetime (ever) ED: (anorexia nervosa (AN, n 151), bulimia nervosa (BN, n 186) or both (AN+BN, n 77)). Women reported usual food consumption using a FFQ at 32 weeks of gestation. Nutrient intakes, frequency of consumption of food groups and overall dietary patterns were examined. Women with lifetime ED were compared with control women using linear regression and logistic regression (as appropriate) after adjustment for relevant covariates, and for multiple comparisons. Women with lifetime ED scored higher on the 'vegetarian' dietary pattern; they had a lower intake of meat, which was compensated by a higher consumption of soya products and pulses compared with the controls. Lifetime AN increased the risk for a high ( ≥ 2500 g/week) caffeine consumption in pregnancy. No deficiencies in mineral and vitamin intake were evident across the groups, although small differences were observed in macronutrient intakes. In conclusion, despite some differences in food group consumption, women with lifetime ED had similar patterns of nutrient intake to healthy controls. Important differences in relation to meat eating and vegetarianism were highlighted, as well as high caffeine consumption. These differences might have an important impact on fetal development.

  6. Product lifetime, energy efficiency and climate change: A case study of air conditioners in Japan.

    PubMed

    Nishijima, Daisuke

    2016-10-01

    This study proposed a modelling technique for estimating life-cycle CO2 emissions of durable goods by considering changes in product lifetime and energy efficiency. The stock and flow of durable goods was modelled by Weibull lifetime distributions and the trend in annual energy efficiency (i.e., annual electricity consumption) of an "average" durable good was formulated as a reverse logistic curve including a technologically critical value (i.e., limit energy efficiency) with respect to time. I found that when the average product lifetime is reduced, there is a trade-off between the reduction in emissions during product use (use phase), due to the additional purchases of new, more energy-efficient air conditioners, and the increase in emissions arising from the additional production of new air conditioners stimulated by the reduction of the average product lifetime. A scenario analysis focused on residential air conditioners in Japan during 1972-2013 showed that for a reduction of average lifetime of 1 year, if the air conditioner energy efficiency limit can be improved by 1.4% from the estimated current efficiency level, then CO2 emissions can be reduced by approximately the same amount as for an extension of average product lifetime of 1 year. PMID:27423771

  7. Product lifetime, energy efficiency and climate change: A case study of air conditioners in Japan.

    PubMed

    Nishijima, Daisuke

    2016-10-01

    This study proposed a modelling technique for estimating life-cycle CO2 emissions of durable goods by considering changes in product lifetime and energy efficiency. The stock and flow of durable goods was modelled by Weibull lifetime distributions and the trend in annual energy efficiency (i.e., annual electricity consumption) of an "average" durable good was formulated as a reverse logistic curve including a technologically critical value (i.e., limit energy efficiency) with respect to time. I found that when the average product lifetime is reduced, there is a trade-off between the reduction in emissions during product use (use phase), due to the additional purchases of new, more energy-efficient air conditioners, and the increase in emissions arising from the additional production of new air conditioners stimulated by the reduction of the average product lifetime. A scenario analysis focused on residential air conditioners in Japan during 1972-2013 showed that for a reduction of average lifetime of 1 year, if the air conditioner energy efficiency limit can be improved by 1.4% from the estimated current efficiency level, then CO2 emissions can be reduced by approximately the same amount as for an extension of average product lifetime of 1 year.

  8. Fluorescence optimisation and lifetime studies of fingerprints treated with magnetic powders.

    PubMed

    Seah, L K; Dinish, U S; Phang, W F; Chao, Z X; Murukeshan, V M

    2005-09-10

    Fluorescence study plays a significant role in fingerprint detection when conventional chemical enhancement methods fail. The basic properties of fluorescence emission such as colour, intensity and lifetime could be well exploited in the detection of latent fingerprints under steady state and in dynamic methods. This paper describes a systematic study of fluorescence emission intensity from fingerprint samples treated with different magnetic powders. Understanding of suitable excitation wavelength required for getting maximum fluorescence emission intensity could be beneficial when selecting the appropriate fluorescent powders for the fingerprint detection. Lifetime study of fingerprints treated with various magnetic powders was also carried out. The importance of lifetime study is well explained through the time-resolved (TR) imaging of fingerprints with nanosecond resolution. Results from the TR imaging study revealed an improvement in the fingerprint image contrast. This is significant when the print is deposited on fluorescing background and its emission wavelength is close to that of treated fingerprint.

  9. Beam halo studies in LEHIPA DTL

    NASA Astrophysics Data System (ADS)

    Roy, S.; Pande, R.; Rao, S. V. L. S.; Krishnagopal, S.; Singh, P.

    2015-11-01

    The Low Energy High Intensity Proton Accelerator (LEHIPA) project at Bhabha Atomic Research Centre (BARC) consists of a 20 MeV, 30 mA proton linac. The accelerator comprises of a 3 MeV Radio Frequency Quadrupole (RFQ) and a 20 MeV Drift Tube Linac (DTL). In such high intensity accelerators, beam halos are of concern as they not only cause an increase in emittance, but also lead to beam loss and radio activation. We have studied the effect of beam mismatch at the DTL input on halo formation and propagation. The particle core model is used to excite the three envelope eigen modes; the quadrupole mode, the fast mode and the slow mode by giving input beam mismatch. These modes get damped as the beam progresses through the DTL. The damping mechanism is clearly Landau damping and leads to increase in rms emittance of the beam. The evolution of these modes and the corresponding increase in beam emittance and maximum beam extent, as the beam propagates through the DTL, has been studied for different space charge tunes. The halo parameter based on the definition of Allen and Wangler has been calculated. It is seen that beam halos are very important for LEHIPA DTL, even at 20 MeV and leads to emittance and beam size increase and also to beam loss in some cases. The longitudinal halo is present even without mismatch and transverse halos arise in the presence of beam mismatch.

  10. Collimation Studies with Hollow Electron Beams

    SciTech Connect

    Stancari, G.; Annala, G.; Johnson, T.R.; Saewert, G.W.; Shiltsev, V.; Still, D.A.; Valishev, A.; /Fermilab

    2011-08-01

    Recent experimental studies at the Fermilab Tevatron collider have shown that magnetically confined hollow electron beams can act as a new kind of collimator for high-intensity beams in storage rings. In a hollow electron beam collimator, electrons enclose the circulating beam. Their electric charge kicks halo particles transversely. If their distribution is axially symmetric, the beam core is unaffected. This device is complementary to conventional two-stage collimation systems: the electron beam can be placed arbitrarily close to the circulating beam; and particle removal is smooth, so that the device is a diffusion enhancer rather than a hard aperture limitation. The concept was tested in the Tevatron collider using a hollow electron gun installed in one of the existing electron lenses. We describe some of the technical aspects of hollow-beam scraping and the results of recent measurements.

  11. Lifetime for Li-like Ti 1s2s2p {sup 4}P{sub 5/2}{sup o} level using a mode of beam-two-foil experiments

    SciTech Connect

    Nandi, T.; Ahmad, Nissar; Wani, A.A.

    2005-08-15

    The option of varying thickness of the fixed foil in the beam-two-foil technique has been incorporated in our experimental setup. It gives an opportunity to explore a new mode of this technique. In the current study, we have investigated the lifetime of the 1s2s2p {sup 4}P{sub 5/2}{sup o} level in Li-like titanium using this technique. The data showed a dependence of foil thickness of the fixed foil on the interactions of levels produced in the first foil. Average lifetime obtained for the Li-like titanium 1s2s2p {sup 4}P{sub 5/2}{sup o} level (200{+-}12 ps) is compared very well with the earlier theoretical and experimental values.

  12. Studies of beam dynamics in relativistic klystron two- beam accelerators

    NASA Astrophysics Data System (ADS)

    Lidia, Steven Michael

    Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band (~8-12 GHz) through Ka-band (~30-35 GHz) frequency regions. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. A mapping algorithm is used so that tens or hundreds of thousands of macroparticles can be pushed from the solution of a few hundreds of differential equations. This is a great cost-savings device from the standpoint of CPU cycles. It can increase by several orders of magnitude the number of macroparticles that take place in the simulation, enabling more accurate modeling of the evolution of the beam distribution and enhanced sensitivity to effects due to the beam's halo. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split- operator algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The beam-cavity interaction is analyzed and divided naturally into two distinct times scales. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 TW of power from 40 input, gain

  13. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB.

    PubMed

    Ren, Haitao; Pozdeyev, Eduard; Lund, Steven M; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-01

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper. PMID:26932091

  14. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB

    NASA Astrophysics Data System (ADS)

    Ren, Haitao; Pozdeyev, Eduard; Lund, Steven M.; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-01

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

  15. Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB.

    PubMed

    Ren, Haitao; Pozdeyev, Eduard; Lund, Steven M; Machicoane, Guillaume; Wu, Xiaoyu; Morgan, Glenn

    2016-02-01

    To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.

  16. The study of synthetic food dyes by positron annihilation lifetime spectroscopy.

    NASA Astrophysics Data System (ADS)

    Pivtsaev, A. A.; Razov, V. I.

    2015-06-01

    By method of positron annihilation lifetime spectroscopy (PALS), substances are food dyes were studied: E-102 (Tartrazine), E-124 (Ponso 4R), E 132 (Indigo carmine), E-133 (Brilliant Blue), E-151 (Black Shiny). They are examined for the presence of carcinogenic properties. The difference between dyes having explicit carcinogenic properties and mutagenic properties (non-explicit carcinogens) is established.

  17. Field of Study in College and Lifetime Earnings in the United States

    ERIC Educational Resources Information Center

    Kim, ChangHwan; Tamborini, Christopher R.; Sakamoto, Arthur

    2015-01-01

    Our understanding about the relationship between education and lifetime earnings often neglects differences by field of study. Utilizing data that match respondents in the Survey of Income and Program Participation to their longitudinal earnings records based on administrative tax information, we investigate the trajectories of annual earnings…

  18. Alpha-induced reaction studies using low-energy RI beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Kahl, D.; Hu, J.; Kubono, S.; Hayakawa, S.; Hashimoto, T.

    2012-11-01

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Studies on proton and alpha resonance scatterings, (α, p) reactions, and other types of measurements (β-decay lifetimes etc.) have been performed using RI beams at CRIB, motivated by interests on astrophysical reactions and exotic nuclear structure. Among the studies at CRIB, the measurement of 7Li+α/7Be+α resonant scatterings are presented.

  19. Alpha-induced reaction studies using low-energy RI beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Kahl, D.; Hu, J.; Kubono, S.; Hayakawa, S.; Hashimoto, T.

    2012-11-12

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Studies on proton and alpha resonance scatterings, ({alpha}, p) reactions, and other types of measurements ({beta}-decay lifetimes etc.) have been performed using RI beams at CRIB, motivated by interests on astrophysical reactions and exotic nuclear structure. Among the studies at CRIB, the measurement of {sup 7}Li+{alpha}/{sup 7}Be+{alpha} resonant scatterings are presented.

  20. Lifetime toxicity/carcinogenicity studies of FD & C red no. 40 (allura red) in mice.

    PubMed

    Borzelleca, J F; Olson, J W; Reno, F E

    1991-05-01

    FD & C Red No. 40 (allura red) was fed to Charles River HaM/ICR (CD-1) (study A) and CD-1 outbred (study B) mice as a dietary admixture in two separate lifetime toxicity/carcinogenicity studies. Each study included an in utero exposure phase during which the colouring was fed at dietary concentrations of 0.0, 0.37, 1.39 or 5.19% throughout the mating, gestation and lactation periods. After random selection, the lifetime exposure phase was initiated using the same dietary concentrations with 50 mice/sex/group in study A and 100 mice/sex/group in study B. Exposure was for 104 wk in study A and 109 wk in study B. No compound-related adverse effects were observed. The no-observable-adverse-effect level in these studies was 5.19%; approximately 7300 and 8300 mg/kg body weight/day for male and female mice, respectively.

  1. Lifetime-weighted photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Forbrich, A.; Shao, P.; Shi, Wei; Zemp, Roger J.

    2015-03-01

    It has previously been shown that photoacoustic imaging can interrogate lifetimes of exogenous agents by a sequence of pulses with varying pump-probe delay intervals. Rather than attempt to unmix molecules based on their composite lifetime profile, we introduce a technique called lifetime weighted imaging, which preferentially weights signals from chromophores with long lifetimes (including exogenous contrast agents such as methylene blue and porphyrins with microsecond-scale lifetimes) while nulling chromophores with short lifetimes (including hemoglobin with ps-ns-scale lifetimes). A probe beam is used to interrogate samples with or without a pump beam. By subtracting probe-beam photoacoustic signals with pump- from those without a pump excitation, we effectively eliminate probe signals from chromophores with short lifetimes while preserving excited-state photoacoustic signals from long-lifetimes. This differential signal will be weighted by a decaying exponential function of the pump-probe delay divided by the exogenous agent lifetime. This technique enabled the imaging of both triplet excited state lifetime and ground-state recovery lifetime. We demonstrate the oxygen-dependent lifetime of both methylene blue and porphyrins. Lifetimeweighted imaging could be used for photodynamic therapy dosimetry guidance, oxygen sensing, or other molecular imaging applications.

  2. Lifetime of anode polymer in magnetically insulated ion diodes for high-intensity pulsed ion beam generation

    SciTech Connect

    Zhu, X. P.; Dong, Z. H.; Han, X. G.; Xin, J. P.; Lei, M. K.

    2007-02-15

    Generation of high-intensity pulsed ion beam (HIPIB) has been studied experimentally using polyethylene as the anode polymer in magnetically insulated ion diodes (MIDs) with an external magnetic field. The HIPIB is extracted from the anode plasma produced during the surface discharging process on polyethylene under the electrical and magnetic fields in MIDs, i.e., high-voltage surface breakdown (flashover) with bombardments by electrons. The surface morphology and the microstructure of the anode polymer are characterized using scanning electron microscopy and differential scanning calorimetry, respectively. The surface roughening of the anode polymer results from the explosive release of trapped gases or newly formed gases under the high-voltage discharging, leaving fractured surfaces with bubble formation. The polyethylene in the surface layer degrades into low-molecular-weight polymers such as polyethylene wax and paraffin under the discharging process. Both the surface roughness and the fraction of low molecular polymers apparently increase as the discharging times are prolonged for multipulse HIPIB generation. The changes in the surface morphology and the composition of anode polymer lead to a noticeable decrease in the output of ion beam intensity, i.e., ion current density and diode voltage, accompanied with an increase in instability of the parameters with the prolonged discharge times. The diode voltage (or surface breakdown voltage of polymer) mainly depends on the surface morphology (or roughness) of anode polymers, and the ion current density on the composition of anode polymers, which account for the two stages of anode polymer degradation observed experimentally, i.e., stage I which has a steady decrease of the two parameters and stage II which shows a slow decrease, but with an enhanced fluctuation of the two parameters with increasing pulses of HIPIB generation.

  3. Determination of CdTe bulk carrier lifetime and interface recombination velocity of CdTe/MgCdTe double heterostructures grown by molecular beam epitaxy

    SciTech Connect

    Zhao, Xin-Hao; Campbell, Calli M.; DiNezza, Michael J.; Liu, Shi; Zhao, Yuan; Zhang, Yong-Hang

    2014-12-22

    The bulk Shockley-Read-Hall carrier lifetime of CdTe and interface recombination velocity at the CdTe/Mg{sub 0.24}Cd{sub 0.76}Te heterointerface are estimated to be around 0.5 μs and (4.7 ± 0.4) × 10{sup 2 }cm/s, respectively, using time-resolved photoluminescence (PL) measurements. Four CdTe/MgCdTe double heterostructures (DHs) with varying CdTe layer thicknesses were grown on nearly lattice-matched InSb (001) substrates using molecular beam epitaxy. The longest lifetime of 179 ns is observed in the DH with a 2 μm thick CdTe layer. It is also shown that the photon recycling effect has a strong influence on the bulk radiative lifetime, and the reabsorption process affects the measured PL spectrum shape and intensity.

  4. Relationship between the microscopic and macroscopic world in optical oxygen sensing: a luminescence lifetime microscopy study.

    PubMed

    López-Gejo, Juan; Haigh, David; Orellana, Guillermo

    2010-02-01

    An investigation based on confocal fluorescence lifetime imaging microscopy (FLIM) of silica-loaded silicone films doped with a molecular oxygen-sensitive ruthenium(II) polyazaheterocyclic complex is presented. The effect of the silica type (hydrophilic/hydrophobic), particle size and amount of silica filler on the luminescence decay of the immobilized indicator dye has thoroughly been studied. A higher amount of hydrophilic silica leads to both a higher solubility of molecular oxygen into the silicone film and to higher levels of the metal indicator dye. Thus, incorporation of 10% (by wt) pyrogenic silica into silicone shortens the mean luminescence lifetime from 1.4 to 0.9 micros. However, an excess of filler may lead to overloading of the dye into the film producing new phenomena such as triplet-triplet annihilation and excitation energy homotransfer, as observed from their influence on the emission lifetime of the metal complex. Those phenomena do not take place when trimethylated silica (hydrophobic filler) is used. In this case, no increase on the oxygen or dye concentration is observed after addition of the filler and no significant reduction of the luminescence lifetime is measured. Both the addition of silica and the possible precipitation of dye crystals lead to the appearance of microdomains where the molecular probe exhibits widely different excited state lifetimes. For the first time, such microdomains within the oxygen sensing layer are visualized and analyzed by means of FLIM, showing the potential of this technique and the usefulness of our conclusions to the future design and development of novel luminescent oxygen sensor films for environmental and process analysis.

  5. Minority Carrier Lifetime and Photoluminescence Studies of Antimony-Based Superlattices

    NASA Technical Reports Server (NTRS)

    Hoglund, Linda; Soibel, Alexander; Ting, David Z.; Khoshakhlagh, Arezou; Hill, Cory J.; Gunapala, Sarath D.

    2012-01-01

    In this paper, we have used the OMR technique to study the minority carrier lifetimes in three InAs/GaSb-photoluminescence (PL) structures with different number of periods in the absorber: 300, 400 and 600 periods respectively. The feasibility of using a visible 643 nm laser source with short penetration depth for lifetime measurements was studied by comparing the achieved results to measurements performed on the same samples with a 1550 nm IR laser source, which penetrates much deeper into the sample. Despite the differences in excitation wavelengths and penetration depths, the results from both measurements were very similar. This indicates that the diffusion length is long enough to facilitate a homogeneous distribution of excess carriers in the material.

  6. The extended Touschek lifetime

    SciTech Connect

    Bizek, H.M.

    1996-02-01

    With the advent of synchrotron radiation sources, the issue of beam lifetime becomes increasingly important. Users of these machines need to perform experiments which seldom last 15 minutes, but require hours for their completion. Therefore, the beam should circulate stably for hours. The beam of the Advanced Photon Source (APS) storage ring at Argonne National Laboratory is assumed to circulate stably for a minimum of 10 hours. The main contributions to the total beam lifetime (which is the inverse of the loss rate) come from residual gas scattering and Touschek scattering. The residual gas scattering is comprised of single Coulomb scattering and bremsstrahlung. The single-Coulomb scattering involves elastic collisions, while bremsstrahlung involves inelastic collisions, between the bunch and the surrounding residual gas. In the calculation the authors take the gas to be nitrogen at a pressure of 1 nTorr. Touschek scattering involves scattering of particles within the bunch, transferring energy among themselves. Such an energy transfer, if large enough, may eject the particle out of the bunch, thus causing it to be lost. Let us not forget the residual-gas lifetime. As pointed out, the calculation of this lifetime is done for the very low pressure of 1 nTorr. If the pressure is higher, the residual-gas lifetime will be smaller. This will further reduce the total beam lifetime, causing it to slip deeper below the minimum lifetime for stable storage ring operation. They begin this article by reviewing the Touschek integral and the associated limits of integration. The program ZAP has been altered to take into account the possible loss due to induced betatron oscillations. At each lattice position the energy loss required to produce, by coupling, a vertical oscillation that exceeds the vertical aperture is calculated. When this energy loss is less than the rf bucket half-height, it replaces the rf bucket half-height in the Touschek integral.

  7. UCNtau: Study of Lifetime Measurement in a Magneto-Gravitational Trap

    SciTech Connect

    Saunders, Alexander; Salvat, D.; Adamek, E.; Bowman, D.; Clayton, S.; Cude, C.; Fox, W.; Hogan, G.; Hickerson, K.; Holley, A. T.; Liu, C.-Y.; Makela, M.; Manus, G.; Morris, C.; Penttila, S.; Ramsey, J.; Sawtelle, S.; Solberg, K.; Vanderwerp, J.; VornDick, B.; Walstrom, P.; Wang, Z.; Young, A. R.

    2014-01-01

    The UCNtau project is intended to develop a new measurement of the neutron lifetime using ultra-cold neutrons (UCNs) stored in a magneto-gravitational trap. In this article, we will describe the development of the experiment so far, including the trap itself, the UCN transport and monitoring system, the neutron detection methods, and the Monte Carlo simulations that have been used to model these elements. Finally, we will describe the first systematic effects that we plan to study using this apparatus.

  8. The Association of Early Substance Use with Lifetime/Past Year Contraction of Sexually Transmitted Diseases: A National Study

    ERIC Educational Resources Information Center

    Merianos, Ashley L.; Rosen, Brittany L.; King, Keith A.; Vidourek, Rebecca A.; Fehr, Sara K.

    2015-01-01

    The study purpose is to examine the impact of early substance use on lifetime and past year contraction of sexually transmitted diseases (STDs), including chlamydia, gonorrhea, herpes, and syphilis. A secondary analysis of the 2012 National Survey on Drug Use and Health (N = 52,529) was conducted to determine if lifetime or past year STD…

  9. Experimental and simulation studies of beam-beam compensation with Tevatron electron lenses

    SciTech Connect

    Kamerdzhiev, V.; Alexahin, Y.; Shiltsev, V.; Valishev, A.; Zhang, X.L.; Shatilov, D.; /Novosibirsk, IYF

    2007-06-01

    Initially the Tevatron Electron Lenses (TELs) were intended for compensation of the beam-beam effect on the antiproton beam [1]. Owing to recent increase in the number of antiprotons and reduction in their emittance, it is the proton beam now that suffers most from the beam-beam effect [2]. We present results of beam studies, compare them with the results of computer simulations using LIFETRAC code and discuss possibilities of further improvements of the Beam-Beam Compensation efficiency in the Tevatron.

  10. Studies on Beam Formation in an Atomic Beam Source

    SciTech Connect

    Nass, A.; Steffens, E.; Stancari, M.

    2009-08-04

    Atomic beam sources (ABS) are widely used workhorses producing polarized atomic beams for polarized gas targets and polarized ion sources. Although they have been used for decades the understanding of the beam formation processes is crude. Models were used more or less successfully to describe the measured intensity and beam parameters. ABS's are also foreseen for future experiments, such as PAX [1]. An increase of intensity at a high polarization would be beneficial. A direct simulation Monte-Carlo method (DSMC)[2] was used to describe the beam formation of a hydrogen or deuterium beam in an ABS. For the first time a simulation of a supersonic gas expansion on a molecular level for this application was performed. Beam profile and Time-of-Flight measurements confirmed the simulation results. Furthermore a new method of beam formation was tested, the Carrier Jet method [3], based on an expanded beam surrounded by an over-expanded carrier jet.

  11. Double-robust semiparametric estimator for differences in restricted mean lifetimes in observational studies.

    PubMed

    Zhang, Min; Schaubel, Douglas E

    2012-12-01

    Restricted mean lifetime is often of direct interest in epidemiologic studies involving censored survival times. Differences in this quantity can be used as a basis for comparing several groups. For example, transplant surgeons, nephrologists, and of course patients are interested in comparing posttransplant lifetimes among various types of kidney transplants to assist in clinical decision making. As the factor of interest is not randomized, covariate adjustment is needed to account for imbalances in confounding factors. In this report, we use semiparametric theory to develop an estimator for differences in restricted mean lifetimes although accounting for confounding factors. The proposed method involves building working models for the time-to-event and coarsening mechanism (i.e., group assignment and censoring). We show that the proposed estimator possesses the double robust property; i.e., when either the time-to-event or coarsening process is modeled correctly, the estimator is consistent and asymptotically normal. Simulation studies are conducted to assess its finite-sample performance and the method is applied to national kidney transplant data. PMID:22471876

  12. Cardiovascular Lifetime Risk Predicts Incidence of Coronary Calcification in Individuals With Low Short‐Term Risk: The Dallas Heart Study

    PubMed Central

    Paixao, Andre R. M.; Ayers, Colby R.; Rohatgi, Anand; Das, Sandeep R.; de Lemos, James A.; Khera, Amit; Lloyd‐Jones, Donald; Berry, Jarett D.

    2014-01-01

    Background The absence of coronary artery calcium (CAC) in middle age is associated with very low short‐term risk for coronary events. However, the long‐term implications of a CAC score of 0 are uncertain, particularly among individuals with high cardiovascular lifetime risk. We sought to characterize the association between predicted lifetime risk and incident CAC among individuals with low short‐term risk. Methods and Results We included 754 Dallas Heart Study participants with serial CAC scans (6.9 years apart) and both low short‐term risk and baseline CAC=0. Lifetime risk for cardiovascular disease was estimated according to risk factor burden. Among this group, 365 individuals (48.4%) were at low lifetime risk and 389 (51.6%) at high lifetime risk. High lifetime risk was associated with higher annualized CAC incidence (4.2% versus 2.7%; P < 0.001). Similarly, mean follow‐up CAC scores were higher among participants with high lifetime risk (7.8 versus 2.4 Agatston units). After adjustment for age, sex, and race, high lifetime risk remained independently associated with incident CAC (OR 1.60; 95% CI 1.12 to 2.27; P=0.01). When assessing risk factor burden at the follow‐up visit, 66.7% of CAC incidence observed in the low lifetime risk group occurred among individuals reclassified to a higher short‐ or long‐term risk category. Conclusion Among individuals with low short‐term risk and CAC scores of 0, high lifetime risk is associated with a higher incidence of CAC. These findings highlight the importance of lifetime risk even among individuals with very low short‐term risk. PMID:25424574

  13. Reliable measurement of the Li-like {sub 22}{sup 48}Ti 1s2s2p {sup 4}P{sub 5/2}{sup o} level lifetime by beam-foil and beam-two-foil experiments

    SciTech Connect

    Nandi, T.; Ahmad, Nissar; Wani, A. A.; Marketos, P.

    2006-03-15

    We have determined the lifetime of the Li-like {sub 22}{sup 48}Ti 1s2s2p {sup 4}P{sub 5/2}{sup o} level (210.5{+-}13.5 ps) using data from its x-ray decay channel through beam single- and two-foil experiments, coupled to a multicomponent iterative growth and decay analysis. Theoretical lifetime estimates for this zero-nuclear-spin ion lies within the uncertainty range of our experimental results, indicating that blending contributions to this level from the He-like 1s2p {sup 3}P{sub 2}{sup o} and 1s2s {sup 3}S{sub 1} levels are eliminated within the current approach. A previously reported discrepancy between experimental and theoretical 1s2s2p {sup 4}P{sub 5/2}{sup o} level lifetimes in {sub 23}{sup 51}V may, as a result, be attributed to hyperfine quenching.

  14. Photon beam studies of magnetic materials

    NASA Astrophysics Data System (ADS)

    Lovesey, S. W.

    1994-06-01

    The past decade has seen a surge of activity in the use of photon beam techniques to study magnetic properties of materials. By and large, in this period the experimental work has been accomplished with beams produced by electron synchrotron facilities. To date, it is fair to say that the surge of activity is underpinned by improvements in instrument performance, enjoyed at synchrotron sources, rather than outstanding intellectual advances. In consequence, improvements in the intensity at the sample, and the provision of good beams of polarized photons, which enable polarization induced discrimination effects to be exploited as a means of increasing the signal-to-noise, are particularly significant in the use for magnetic studies of photon beam techniques.

  15. Analytical and experimental investigation of the feasibility of accelerated lifetime testing of materials exposed to an atomic oxygen beam

    NASA Technical Reports Server (NTRS)

    Albridge, Royal; Barnes, Alan; Tolk, Norman

    1993-01-01

    The interaction of atomic particles with surfaces is of both scientific and technological interest. Past work emphasizes the measurement of high-energy sputtering yields. Very little work utilized low-energy beams for which chemical and electronic effects can be important. Even less work has been carried out using well-defined low-energy projectiles. The use of low-energy, reactive projectiles permits one to investigate surface processes that have not been well characterized. As the energy of the projectile decreases, the collisional cascades and spikes, that are common for high-energy projectiles, become less important, and chemical and electronic effects can play a significant role. Aspects of particle-surface interactions are of concern in several areas of technology. For example, the erosion, desorption, and glow of surfaces of spacecraft in orbit are important in the arena of space technology. The materials studied under this contract are of possible use on the exterior portions of the power generation system of Space Station Freedom. Under the original designs, Space Station Freedom's power generation system would generate potential differences on the surface as high as 200 volts. Ions in the plasma that often surround orbiting vehicles would be accelerated by these potentials leading to bombardment and erosion of the exposed surfaces. The major constituent of the atmosphere, approximately 90 percent, in the low earth orbit region is atomic oxygen. Since atomic oxygen is extremely reactive with most materials, chemical effects can arise in addition to the physical sputtering caused by the acceleration of the oxygen ions. Furthermore, the incident oxygen ions can remain embedded in the exposed surfaces, altering the chemical composition of the surfaces. Since the effective binding energy of a chemically altered surface can be quite different from that of the pure substrate, the sputtering yield of a chemically altered surface is usually different also. The low

  16. Minority-carrier diffusion length, minority-carrier lifetime, and photoresponsivity of β-FeSi2 layers grown by molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    Akutsu, Keiichi; Kawakami, Hideki; Suzuno, Mitsushi; Yaguchi, Takashi; Jiptner, Karolin; Chen, Jun; Sekiguchi, Takashi; Ootsuka, Teruhisa; Suemasu, Takashi

    2011-06-01

    We have epitaxially grown undoped β-FeSi2 films on Si(111) substrates via atomic-hydrogen-assisted molecular-beam epitaxy. β-FeSi2 films grown without atomic hydrogen exhibited p-type conduction with a hole density of over 1019 cm-3 at room temperature (RT). In contrast, those prepared with atomic hydrogen showed n-type conduction and had a residual electron density that was more than two orders of magnitude lower than the hole density of films grown without atomic hydrogen (of the order of 1016 cm-3 at RT). The minority-carrier diffusion length was estimated to be approximately 16 μm using an electron-beam-induced current technique; this value is twice as large as that for β-FeSi2 prepared without atomic hydrogen. This result could be well explained in terms of the minority-carrier lifetimes measured by a microwave photoconductance decay technique. The 1/e decay time using a 904 nm laser pulse was approximately 17 μs, which is much longer than that for β-FeSi2 prepared without atomic hydrogen (3 μs). The photoresponsivity reached 13 mA/W at 1.31 μm, which is the highest value ever reported for β-FeSi2 films.

  17. Minority-carrier diffusion length, minority-carrier lifetime, and photoresponsivity of {beta}-FeSi{sub 2} layers grown by molecular-beam epitaxy

    SciTech Connect

    Akutsu, Keiichi; Kawakami, Hideki; Suzuno, Mitsushi; Yaguchi, Takashi; Jiptner, Karolin; Chen, Jun; Sekiguchi, Takashi; Ootsuka, Teruhisa; Suemasu, Takashi

    2011-06-15

    We have epitaxially grown undoped {beta}-FeSi{sub 2} films on Si(111) substrates via atomic-hydrogen-assisted molecular-beam epitaxy. {beta}-FeSi{sub 2} films grown without atomic hydrogen exhibited p-type conduction with a hole density of over 10{sup 19} cm{sup -3} at room temperature (RT). In contrast, those prepared with atomic hydrogen showed n-type conduction and had a residual electron density that was more than two orders of magnitude lower than the hole density of films grown without atomic hydrogen (of the order of 10{sup 16} cm{sup -3} at RT). The minority-carrier diffusion length was estimated to be approximately 16 {mu}m using an electron-beam-induced current technique; this value is twice as large as that for {beta}-FeSi{sub 2} prepared without atomic hydrogen. This result could be well explained in terms of the minority-carrier lifetimes measured by a microwave photoconductance decay technique. The 1/e decay time using a 904 nm laser pulse was approximately 17 {mu}s, which is much longer than that for {beta}-FeSi{sub 2} prepared without atomic hydrogen (3 {mu}s). The photoresponsivity reached 13 mA/W at 1.31 {mu}m, which is the highest value ever reported for {beta}-FeSi{sub 2} films.

  18. Photo-degradation of Lexan polycarbonate studied using positron lifetime spectroscopy

    SciTech Connect

    Hareesh, K.; Sanjeev, Ganesh; Pandey, A. K.; Meghala, D.; Ranganathaiah, C.

    2013-02-05

    The free volume properties of pristine and UV irradiated Lexan polycarbonate have been investigated using Positron Lifetime Spectroscopy (PLS). The decrease in o-Ps life time and free volume size of irradiated sample is attributed to free volume modification and formation of more stable free radicals. These free radicals are formed due to the breakage of C-O bonds in Lexan polycarbonate after irradiation. This is also supported by the decrease in the intensity of C-O bond after exposure to UV-radiation as studied from Fourier Transform Infrared (FTIR) spectroscopy and it also shows that benzene ring does not undergo any changes after irradiation.

  19. Studies on the Use of Liquid Surface Passivation for Lifetime Measurements on Good-Quality Silicon Wafers

    SciTech Connect

    Devayajanam, S.; Rupnowski, P.; Shet, S.; Sopori, B. L.; Ravindra, N. M.; Caskey, D.; Chang, J.; Covington, J.

    2011-01-01

    We evaluated several liquid passivants, viz. solutions of iodine ethanol (IE), quinhydrone methanol (QHM), and potassium cyanide (KCN), for measuring minority-carrier lifetime. Lifetime was measured by the WCT-100 (Sinton Instruments) and WT-2000 (Semilab). Our results show that both IE and QHM passivation are reliable mechanisms. We also find that the KCN solution is moderately passivating on oxidized surfaces, but is only minimally effective on bare Si surfaces. This paper presents details of our studies. In particular, the effect of illumination on IE-passivated surfaces and possible reasons for variations in lifetime measurement are discussed.

  20. Baseline and lifetime alcohol consumption and risk of differentiated thyroid carcinoma in the EPIC study

    PubMed Central

    Sen, Abhijit; Tsilidis, Konstantinos K; Allen, Naomi E; Rinaldi, Sabina; Appleby, Paul N; Almquist, Martin; Schmidt, Julie A; Dahm, Christina C; Overvad, Kim; Tjønneland, Anne; Rostgaard-Hansen, Agnetha L; Clavel-Chapelon, Françoise; Baglietto, Laura; Boutron-Ruault, Marie-Christine; Kühn, Tilman; Katze, Verena A; Boeing, Heiner; Trichopoulou, Antonia; Tsironis, Christos; Lagiou, Pagona; Palli, Domenico; Pala, Valeria; Panico, Salvatore; Tumino, Rosario; Vineis, Paolo; Bueno-de-Mesquita, HB(as); Peeters, Petra H; Hjartåker, Anette; Lund, Eiliv; Weiderpass, Elisabete; Quirós, J Ramón; Agudo, Antonio; Sánchez, María- José; Arriola, Larraitz; Gavrila, Diana; Gurrea, Aurelio Barricarte; Tosovic, Ada; Hennings, Joakim; Sandström, Maria; Romieu, Isabelle; Ferrari, Pietro; Zamora-Ros, Raul; Khaw, Kay-Tee; Wareham, Nicholas J; Riboli, Elio; Gunter, Marc; Franceschi, Silvia

    2015-01-01

    Background: Results from several cohort and case–control studies suggest a protective association between current alcohol intake and risk of thyroid carcinoma, but the epidemiological evidence is not completely consistent and several questions remain unanswered. Methods: The association between alcohol consumption at recruitment and over the lifetime and risk of differentiated thyroid carcinoma was examined in the European Prospective Investigation into Cancer and Nutrition. Among 477 263 eligible participants (70% women), 556 (90% women) were diagnosed with differentiated thyroid carcinoma over a mean follow-up of 11 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariable Cox proportional hazards models. Results: Compared with participants consuming 0.1–4.9 g of alcohol per day at recruitment, participants consuming 15 or more grams (approximately 1–1.5 drinks) had a 23% lower risk of differentiated thyroid carcinoma (HR=0.77; 95% CI=0.60–0.98). These findings did not differ greatly when analyses were conducted for lifetime alcohol consumption, although the risk estimates were attenuated and not statistically significant anymore. Similar results were observed by type of alcoholic beverage, by differentiated thyroid carcinoma histology or according to age, sex, smoking status, body mass index and diabetes. Conclusions: Our study provides some support to the hypothesis that moderate alcohol consumption may be associated with a lower risk of papillary and follicular thyroid carcinomas. PMID:26313664

  1. Dynamic modelling and experimental study of cantilever beam with clearance

    NASA Astrophysics Data System (ADS)

    Li, B.; Jin, W.; Han, L.; He, Z.

    2012-05-01

    Clearances occur in almost all mechanical systems, typically such as the clearance between slide plate of gun barrel and guide. Therefore, to study the clearances of mechanisms can be very important to increase the working performance and lifetime of mechanisms. In this paper, rigid dynamic modelling of cantilever with clearance was done according to the subject investigated. In the rigid dynamic modelling, clearance is equivalent to the spring-dashpot model, the impact of beam and boundary face was also taken into consideration. In ADAMS software, the dynamic simulation was carried out according to the model above. The software simulated the movement of cantilever with clearance under external excitation. Research found: When the clearance is larger, the force of impact will become larger. In order to study how the stiffness of the cantilever's supporting part influences natural frequency of the system, A Euler beam which is restricted by a draught spring and a torsion spring at its end was raised. Through numerical calculation, the relationship between natural frequency and stiffness was found. When the value of the stiffness is close to the limit value, the corresponding boundary condition is illustrated. An ADAMS experiment was carried out to check the theory and the simulation.

  2. Gamma Putty dosimetric studies in electron beam.

    PubMed

    Gloi, Aime M

    2016-01-01

    Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83), bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively) and measured the ionizing radiation on the central axis (CAX) for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI) measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12-20 MeV) and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6-9 MeV). PMID:27651563

  3. Gamma Putty dosimetric studies in electron beam

    PubMed Central

    Gloi, Aime M.

    2016-01-01

    Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83), bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively) and measured the ionizing radiation on the central axis (CAX) for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI) measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12–20 MeV) and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6–9 MeV).

  4. Gamma Putty dosimetric studies in electron beam

    PubMed Central

    Gloi, Aime M.

    2016-01-01

    Traditionally, lead has been used for field shaping in megavoltage electron beams in radiation therapy. In this study, we analyze the dosimetric parameters of a nontoxic, high atomic number (Z = 83), bismuth-loaded material called Gamma Putty that is malleable and can be easily molded to any desired shape. First, we placed an ionization chamber at different depths in a solid water phantom under a Gamma Putty shield of thickness (t = 0, 3, 5, 10, 15, 20, and 25 mm, respectively) and measured the ionizing radiation on the central axis (CAX) for electron beam ranging in energies from 6 to 20 MeV. Next, we investigated the relationship between the relative ionization (RI) measured at a fixed depth for several Gamma Putty shield at different cutout diameters ranging from 2 to 5 cm for various beam energies and derived an exponential fitting equation for clinical purposes. The dose profiles along the CAX show that bremsstrahlung dominates for Gamma Putty thickness >15 mm. For high-energy beams (12–20 MeV) and all Gamma Putty thicknesses up to 25 mm, RI below 5% could not be achieved due to the strong bremsstrahlung component. However, Gamma Putty is a very suitable material for reducing the transmission factor below 5% and protecting underlying normal tissues for low-energy electron beams (6–9 MeV). PMID:27651563

  5. Voids in mixed-cation silicate glasses: Studies by positron annihilation lifetime and Fourier transform infrared spectroscopies.

    PubMed

    Reben, M; Golis, E; Filipecki, J; Sitarz, M; Kotynia, K; Jeleń, P; Grelowska, I

    2014-08-14

    PALS in comparison with FTIR studies have been applied to investigate the structure of different oxide glasses. Three components of the positron lifetime τ (τ1 para- and τ3 ortho-positronium and τ2 intermediate lifetime component) and their intensities were obtained. The results of the calculation of mean values of positron lifetimes for the investigated glasses showed the existence of a long-living component on the positron annihilation lifetime spectra. From the Tao-Eldrup formula we can estimate the size of free volume. On the basis of the measurements we can conclude that the size and fraction of free volume reaches the biggest value for the fused silica glass. The degree of network polymerisation increases void size.

  6. Electron beam, laser beam and plasma arc welding studies

    NASA Technical Reports Server (NTRS)

    Banas, C. M.

    1974-01-01

    This program was undertaken as an initial step in establishing an evaluation framework which would permit a priori selection of advanced welding processes for specific applications. To this end, a direct comparison of laser beam, electron beam and arc welding of Ti-6Al-4V alloy was undertaken. Ti-6Al-4V was selected for use in view of its established welding characteristics and its importance in aerospace applications.

  7. Degradation of encapsulants for photovoltaic modules made of ethylene vinyl acetate studied by positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Hagihara, Hideaki; Kunioka, Masao; Suda, Hiroyuki; Hara, Yukiko; Masuda, Atsushi

    2016-10-01

    The structure of ethylene vinyl acetate (EVA) encapsulants of crystalline-Si photovoltaic modules after the damp heat (DH) test was evaluated by positron annihilation lifetime spectroscopy (PALS). A reduction in free-volume hole size, which indicates the progress of deacetylation, was observed after the DH test. The difference in lifetime (Δτ) between the initial and DH-tested samples clearly increased after the DH test for 3000 h. The increase in Δτ was correlated with the acetic acid concentration in the EVA estimated by ion chromatography. The depth profile analysis by slow positron beam PALS revealed that Δτ in the near-surface region of the Si-cell side was significantly larger than that of the cover-glass side. This result indicates that deacetylation near the Si cell/EVA interface is accelerated.

  8. Study of PRIMAVERA steel samples by positron annihilation spectroscopy technique II - Lifetime measurements

    NASA Astrophysics Data System (ADS)

    Krsjak, V.; Grafutin, V.; Ilyukhina, O.; Burcl, R.; Ballesteros, A.; Hähner, P.

    2012-02-01

    In the present article, a positron annihilation lifetime technique was used for the study of VVER-440/230 weld materials, manufactured in the frame of the international PRIMAVERA project on microstructural investigation of the irradiated WWER-440 reactor pressure vessel steel. The present results complement our previous report of positron angular correlation experiments and provide in-depth characterization of vacancy type defects behavior under irradiation and thermal treatment. The results give new insight into the previously published atom probe tomography and angular correlation of annihilation radiation studies. The measurements do not show any association of phosphorus or its segregation to the open volume defects investigated by positron annihilation spectroscopy. The embrittlement effects related to the phosphorus seem to be effectively annealed-out during 475 °C thermal treatment and the post annealing microstructure and mechanical properties of the material are consequently affected mostly by agglomerations of vacancy clusters coarsened during thermal treatment.

  9. Imputation method for lifetime exposure assessment in air pollution epidemiologic studies

    PubMed Central

    2013-01-01

    Background Environmental epidemiology, when focused on the life course of exposure to a specific pollutant, requires historical exposure estimates that are difficult to obtain for the full time period due to gaps in the historical record, especially in earlier years. We show that these gaps can be filled by applying multiple imputation methods to a formal risk equation that incorporates lifetime exposure. We also address challenges that arise, including choice of imputation method, potential bias in regression coefficients, and uncertainty in age-at-exposure sensitivities. Methods During time periods when parameters needed in the risk equation are missing for an individual, the parameters are filled by an imputation model using group level information or interpolation. A random component is added to match the variance found in the estimates for study subjects not needing imputation. The process is repeated to obtain multiple data sets, whose regressions against health data can be combined statistically to develop confidence limits using Rubin’s rules to account for the uncertainty introduced by the imputations. To test for possible recall bias between cases and controls, which can occur when historical residence location is obtained by interview, and which can lead to misclassification of imputed exposure by disease status, we introduce an “incompleteness index,” equal to the percentage of dose imputed (PDI) for a subject. “Effective doses” can be computed using different functional dependencies of relative risk on age of exposure, allowing intercomparison of different risk models. To illustrate our approach, we quantify lifetime exposure (dose) from traffic air pollution in an established case–control study on Long Island, New York, where considerable in-migration occurred over a period of many decades. Results The major result is the described approach to imputation. The illustrative example revealed potential recall bias, suggesting that regressions

  10. KENO lifetimes

    SciTech Connect

    Petrie, L.; Parsons, D.K.; Spriggs, G.D.

    1997-01-30

    When performing k-eigenvalue solutions with KENO-V.a, two different prompt neutron lifetimes are estimated - a system lifetime and a neutron generation time. The meaning of these two lifetimes has been ascertained by comparing values of various neutron lifespans/lifetimes predicted by MCNP and DANTSYS based on the neutron-balance theory. The system lifetime in KENO-Va corresponds to the unweighted removal lifetime calculated by both MCNP and DANTSYS. The unweighted removal lifetime is the average time between removal events resulting from a neutron absorption or a neutron leakage. The generation time in KENO-V.a corresponds to the fission lifespan calculated by MCNP, where the fission lifespan in MCNP represents the average time for a newly born neutron to cause another fission. As such, the generation time in KENO-Va does not represent the generation time that appears in the point kinetic model. The generation time in the point kinetic model is the adjoint-weighted removal lifetime divided by k{sub eff}, which is identically equal to the adjoint-weighted neutron production rate. In small bare systems operating in the vicinity of delayed critical, the difference between the adjoint-weighted neutron generation time and the fission lifespan can be as small as a few percent. However, in reflected systems, the difference between these two quantities can be several orders of magnitude. In conclusion, the prompt neutron generation time predicted by KENO-Va corresponds to the fission lifespan of a prompt neutron in a given system. The fission lifespan is the average time from birth-to-fission and, in general, is not a good approximation for the adjoint-weighted neutron generation time that appears in the point-kinetic model.

  11. Beam-single and beam-two-foil experimental facility to study physics of highly charged ions

    SciTech Connect

    Ahmad, Nissar; Wani, A.A.; Ram, R.; Abhilash, S.R.; Kumar, Rakesh; Patnaik, J.K.; De, Sankar; Karn, R.K.; Nandi, T.

    2006-03-15

    A facility for lifetime measurement of metastable states in highly charged ions using the beam-foil technique with a single-foil and a two-foil target has been developed. In the two-foil technique, one foil moves with respect to the other and the option of varying the thickness of the fixed foil online has been implemented. A holder with multiple foils is used as a fixed target, and moved along x, y, and {theta}, the angle of rotation with respect to beam direction along the z axis. Using this facility, the He-like 1s2p {sup 3}P{sub 2}{sup o} and Li-like 1s2s2p {sup 4}P{sub 5l/2}{sup o} titanium lifetimes have been measured and compared with earlier values. In addition to this, the processes which occur when excited states collide with carbon foils of different thicknesses have also been investigated. Preliminary results suggest the scope of studying intrashell transitions during ion-solid collision using this setup. In this article, the setup is described in detail and representative results are briefly discussed.

  12. Beamed-Energy Propulsion (BEP) Study

    NASA Technical Reports Server (NTRS)

    George, Patrick; Beach, Raymond

    2012-01-01

    The scope of this study was to (1) review and analyze the state-of-art in beamed-energy propulsion (BEP) by identifying potential game-changing applications, (2) formulate a roadmap of technology development, and (3) identify key near-term technology demonstrations to rapidly advance elements of BEP technology to Technology Readiness Level (TRL) 6. The two major areas of interest were launching payloads and space propulsion. More generally, the study was requested and structured to address basic mission feasibility. The attraction of beamed-energy propulsion (BEP) is the potential for high specific impulse while removing the power-generation mass. The rapid advancements in high-energy beamed-power systems and optics over the past 20 years warranted a fresh look at the technology. For launching payloads, the study concluded that using BEP to propel vehicles into space is technically feasible if a commitment to develop new technologies and large investments can be made over long periods of time. From a commercial competitive standpoint, if an advantage of beamed energy for Earth-to-orbit (ETO) is to be found, it will rest with smaller, frequently launched payloads. For space propulsion, the study concluded that using beamed energy to propel vehicles from low Earth orbit to geosynchronous Earth orbit (LEO-GEO) and into deep space is definitely feasible and showed distinct advantages and greater potential over current propulsion technologies. However, this conclusion also assumes that upfront infrastructure investments and commitments to critical technologies will be made over long periods of time. The chief issue, similar to that for payloads, is high infrastructure costs.

  13. Measurements of heavy quark and lepton lifetimes

    SciTech Connect

    Jaros, J.A.

    1985-02-01

    The PEP/PETRA energy range has proved to be well-suited for the study of the lifetimes of hadrons containing the b and c quarks and the tau lepton for several reasons. First, these states comprise a large fraction of the total interaction rate in e/sup +/e/sup -/ annihilation and can be cleanly identified. Second, the storage rings have operated at high luminosity and so produced these exotic states copiously. And finally, thanks to the interplay of the Fermi coupling strength, the quark and lepton masses, and the beam energy, the expected decay lengths are in the 1/2 mm range and so are comparatively easy to measure. This pleasant coincidence of cleanly identified and abundant signal with potentially large effects has made possible the first measurements of two fundamental weak couplings, tau ..-->.. nu/sub tau/W and b ..-->.. cW. These measurements have provided a sharp test of the standard model and allowed, for the first time, the full determination of the magnitudes of the quark mixing matrix. This paper reviews the lifetime studies made at PEP during the past year. It begins with a brief review of the three detectors, DELCO, MAC and MARK II, which have reported lifetime measurements. Next it discusses two new measurements of the tau lifetime, and briefly reviews a measurement of the D/sup 0/ lifetime. Finally, it turns to measurements of the B lifetime, which are discussed in some detail. 18 references, 14 figures, 1 table.

  14. Study of UV Cu + Ne – CuBr laser lifetime by statistical methods

    SciTech Connect

    Iliev, I P; Gocheva-Ilieva, S G

    2013-11-30

    On the basis of a large amount of experimental data, statistical investigation of the average lifetime of a UV Cu + Ne – CuBr laser depending on ten input physical laser parameters is carried out. It is found that only three of the parameters have a substantial influence on the laser lifetime. Physical analysis and interpretation of the results are provided. (lasers)

  15. Lifetime increase using passive harmonic cavities insynchrotronlight sources

    SciTech Connect

    Byrd, J.M.; Georgsson, M.

    2000-09-22

    Harmonic cavities have been used in storage rings to increase beam lifetime and Landau damping by lengthening the bunch.The need for lifetime increase is particularly great in the present generation of low to medium energy synchrotron light sources where the small transverse beam sizes lead to relatively short lifetimes from large-angle intrabeam (Touschek) scattering. We review the beam dynamics of harmonic radiofrequency (RF) systems and discuss optimization of the beam lifetime using passive harmonic cavities.

  16. Lung cancer in lifetime nonsmoking men – results of a case-control study in Germany

    PubMed Central

    Kreuzer, M; Gerken, M; Kreienbrock, L; Wellmann, J; Wichmann, H E

    2001-01-01

    Epidemiological studies of lung cancer among nonsmoking men are few. This case–control study was conducted among lifetime nonsmoking men between 1990 and 1996 in Germany to examine lung cancer risk in relation to occupation, environmental tobacco smoke, residential radon, family history of cancer and previous lung disease. A total of 58 male cases with confirmed primary lung cancer and 803 male population controls who had never smoked more than 400 cigarettes in their lifetime were personally interviewed by a standardized questionnaire. In addition, 1-year radon measurements in the living and bedroom of the subjects' last dwelling were carried out. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Having ever worked in a job with known lung carcinogens was associated with a two-fold significantly increased lung cancer risk (OR = 2.2; Cl = 1.0–5.0), adjusted for age and region. The linear trend test for lung-cancer risk associated with radon exposure was close to statistical significance, demonstrating an excess relative risk for an increase in exposure of 100 Bq m−3 of 0.43 (P = 0.052). Nonsignificantly elevated effects of exposure to environmental tobacco smoke in public transportation and in social settings were observed. No associations with a family history of cancer or previous lung diseases were found. Our results indicate that occupational carcinogens and indoor radon may play a role in some lung cancers in nonsmoking men. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11139328

  17. Hyperspectral fluorescence lifetime fibre probe spectroscopy for use in the study and diagnosis of osteoarthritis and skin cancer

    NASA Astrophysics Data System (ADS)

    Thompson, Alex; Manning, Hugh; Brydegaard, Mikkel; Coda, Sergio; Kennedy, Gordon; Patalay, Rakesh; Waitong-Braemming, Ulrika; De Beule, Pieter; Neil, Mark; Andersson-Engels, Stefan; Itoh, Yoshifumi; Bendsøe, Niels; Dunsby, Christopher; Svanberg, Katarina; French, Paul M.

    2011-03-01

    We present the application of two fibre-optic-coupled time-resolved spectrofluorometers and a compact steady-state diffuse reflected light/fluorescence spectrometer to in vivo and ex vivo studies of skin cancer and osteoarthritis. In a clinical study of skin cancer, 27 lesions on 25 patients were investigated in vivo before surgical excision of the region measured. Preliminary analysis reveals a statistically significant decrease in the autofluorescence lifetime of basal cell carcinomas compared to neighbouring healthy tissue. A study of autofluorescence signals associated with the onset of osteoarthritis indicates autofluorescence lifetime changes associated with collagen degradation.

  18. Actin cytoskeleton-dependent Rab GTPase-regulated angiotensin type I receptor lysosomal degradation studied by fluorescence lifetime imaging microscopy

    NASA Astrophysics Data System (ADS)

    Li, Hewang; Yu, Peiying; Sun, Yuansheng; Felder, Robin A.; Periasamy, Ammasi; Jose, Pedro A.

    2010-09-01

    The dynamic regulation of the cellular trafficking of human angiotensin (Ang) type 1 receptor (AT1R) is not well understood. Therefore, we investigated the cellular trafficking of AT1R-enhanced green fluorescent protein (EGFP) (AT1R-EGFP) heterologously expressed in HEK293 cells by determining the change in donor lifetime (AT1R-EGFP) in the presence or absence of acceptor(s) using fluorescence lifetime imaging-fluorescence resonance energy transfer (FRET) microscopy. The average lifetime of AT1R-EGFP in our donor-alone samples was ~2.33 ns. The basal state lifetime was shortened slightly in the presence of Rab5 (2.01+/-0.10 ns) or Rab7 (2.11+/-0.11 ns) labeled with Alexa 555, as the acceptor fluorophore. A 5-min Ang II treatment markedly shortened the lifetime of AT1R-EGFP in the presence of Rab5-Alexa 555 (1.78+/-0.31 ns) but was affected minimally in the presence of Rab7-Alexa 555 (2.09+/-0.37 ns). A 30-min Ang II treatment further decreased the AT1R-EGFP lifetime in the presence of both Rab5- and Rab7-Alexa 555. Latrunculin A but not nocodazole pretreatment blocked the ability of Ang II to shorten the AT1R-EGFP lifetime. The occurrence of FRET between AT1R-EGFP (donor) and LAMP1-Alexa 555 (acceptor) with Ang II stimulation was impaired by photobleaching the acceptor. These studies demonstrate that Ang II-induced AT1R lysosomal degradation through its association with LAMP1 is regulated by Rab5/7 via mechanisms that are dependent on intact actin cytoskeletons.

  19. Association of adolescent obesity and lifetime nulliparity – SWAN, the study of women's health across the nation

    PubMed Central

    Polotsky, Alex J.; Hailpern, Susan M.; Skurnick, Joan H.; LO, Joan C.; Sternfeld, Barbara; Santoro, Nanette

    2010-01-01

    Objective To evaluate whether adolescent obesity is associated with difficulties for becoming pregnant later in life. Design Cross-sectional analysis of baseline data from a longitudinal cohort Setting Multiethnic, community-based observational study of US women Patient(s) 3154 midlife women Main Outcome Measure(s) Lifetime nulliparity and lifetime nulligravidity Result(s) 527 women (16.7%) women had never delivered a baby. Participants were categorized by self-reported high school body mass index (BMI): underweight (< 18.5 kg/m2), normal (18.5 to 24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (> 30 kg/m2). The prevalence of lifetime nulliparity increased progressively across the high school BMI categories: 12.7%, 16.7%, 19.2%, and 30.9%, respectively (p<0.001). Multivariable logistic regression analysis confirmed that women who were obese adolescents had significantly higher odds of remaining childless as compared to normal weight women (odds ratio [OR] 2.84, 95% confidence intervals [CI] 1.59 to 5.10) after adjusting for adult BMI, history of non-gestational amenorrhea, marital status, ethnicity, study site, and measures of socioeconomic status. Furthermore, adolescent obesity was associated with lifetime nulligravidity (OR 3.93, 95% CI 2.12 to 7.26). Conclusion(s) Adolescent obesity is associated with lifetime nulliparity and nulligravidity in midlife U.S. women. PMID:19185860

  20. Repeated Diagnoses of Lifetime Alcohol Use Disorders in a Prospective Study: Insights into the Extent and Nature of the Reliability and Validity Problem

    PubMed Central

    Haeny, Angela M.; Littlefield, Andrew K.; Sher, Kenneth J.

    2014-01-01

    Background Prior research indicates that assessments of lifetime alcohol use disorders (AUDs) show low sensitivity and are unreliable when assessed by a single, retrospective interview. This study sought to replicate and extend previous research by calculating the lifetime prevalence rate of AUDs using both single retrospective assessments of lifetime diagnosis and repeated assessments of both lifetime and past-year diagnoses over a 16-year period within the same high-risk sample. In addition, this study examined factors that contributed to the consistency in reporting lifetime AUDs over time. Methods Using prospective data, the reliability and validity of lifetime estimates of alcohol dependence and AUD were examined in several ways. Data were drawn from a cohort of young adults at high and low risk for alcoholism, originally ascertained as first-time college freshmen (N = 489 at baseline) at a large, public university and assessed over 16 years. Results Compared with using a single, lifetime retrospective assessment of DSM-III disorders assessed at approximately age 34, lifetime estimates derived from using multiple, prospective assessments of both past-year and lifetime AUD were substantially higher (25% single lifetime vs. 41% cumulative past-year vs. 46% cumulative lifetime). This pattern of findings was also found when conducting these comparisons at the symptom level. Further, these results suggest that some factors (e.g., symptoms endorsed, prior consistency in reporting of a lifetime AUD, and family history status) are associated with the consistency in reporting lifetime AUDs over time. Conclusions Based on these findings, lifetime diagnoses using a single measurement occasion should be interpreted with considerable caution given they appear to produce potentially large prevalence underestimates. These results provide further insight into the extent and nature of the reliability and validity problem with lifetime AUDs. PMID:24033811

  1. Lifetimes and electromagnetic transition strength in 157Dy

    NASA Astrophysics Data System (ADS)

    Gladnishki, K. A.; Petkov, P.; Dewald, A.; Jolie, J.; Möller, O.; Saha, B.; Fitzler, A.; Jessen, K.; Tonev, D.; Klug, T.; Heinze, S.; von Brentano, P.; Rainovski, G.; Trichkova, M.; Bazzacco, D.; Ur, C. A.; Farnea, E.; Axiotis, M.; Lunardi, S.; de Angelis, G.; Napoli, D. R.; Marginean, N.; Martinez, T.; Caprio, M. A.

    2016-06-01

    Excited states in 157Dy have been studied by γ-γ coincidence measurements via the reaction 124Sn(36S,3n) at a beam energy of 155MeV. Lifetimes of the relatively lower-spin states in 157Dy were measured by means of the Recoil Distance Dopplershift technique in the coincidence mode. The experiment was performed at the Laboratori Nazionali di Legnaro with the GASP array and the Cologne plunger device. With the same setup a Doppler- shift attenuation (DSA) lifetime measurement was performed for the higher spin states. The Differential decay-curve method was applied for the lifetime determination.

  2. Positron annihilation lifetime study of polyvinylpyrrolidone for nanoparticle-stabilizing pharmaceuticals.

    PubMed

    Shpotyuk, O; Bujňáková, Z; Baláž, P; Ingram, A; Shpotyuk, Y

    2016-01-01

    Positron annihilation lifetime spectroscopy was applied to characterize free-volume structure of polyvinylpyrrolidone used as nonionic stabilizer in the production of many nanocomposite pharmaceuticals. The polymer samples with an average molecular weight of 40,000 g mol(-1) were pelletized in a single-punch tableting machine under an applied pressure of 0.7 GPa. Strong mixing in channels of positron and positronium trapping were revealed in the polyvinylpyrrolidone pellets. The positron lifetime spectra accumulated under normal measuring statistics were analysed in terms of unconstrained three- and four-term decomposition, the latter being also realized under fixed 0.125 ns lifetime proper to para-positronium self-annihilation in a vacuum. It was shown that average positron lifetime extracted from each decomposition was primary defined by long-lived ortho-positronium component. The positron lifetime spectra treated within unconstrained three-term fitting were in obvious preference, giving third positron lifetime dominated by ortho-positronium pick-off annihilation in a polymer matrix. This fitting procedure was most meaningful, when analysing expected positron trapping sites in polyvinylpyrrolidone-stabilized nanocomposite pharmaceuticals. PMID:26444751

  3. Positron annihilation lifetime study of polyvinylpyrrolidone for nanoparticle-stabilizing pharmaceuticals.

    PubMed

    Shpotyuk, O; Bujňáková, Z; Baláž, P; Ingram, A; Shpotyuk, Y

    2016-01-01

    Positron annihilation lifetime spectroscopy was applied to characterize free-volume structure of polyvinylpyrrolidone used as nonionic stabilizer in the production of many nanocomposite pharmaceuticals. The polymer samples with an average molecular weight of 40,000 g mol(-1) were pelletized in a single-punch tableting machine under an applied pressure of 0.7 GPa. Strong mixing in channels of positron and positronium trapping were revealed in the polyvinylpyrrolidone pellets. The positron lifetime spectra accumulated under normal measuring statistics were analysed in terms of unconstrained three- and four-term decomposition, the latter being also realized under fixed 0.125 ns lifetime proper to para-positronium self-annihilation in a vacuum. It was shown that average positron lifetime extracted from each decomposition was primary defined by long-lived ortho-positronium component. The positron lifetime spectra treated within unconstrained three-term fitting were in obvious preference, giving third positron lifetime dominated by ortho-positronium pick-off annihilation in a polymer matrix. This fitting procedure was most meaningful, when analysing expected positron trapping sites in polyvinylpyrrolidone-stabilized nanocomposite pharmaceuticals.

  4. The lifetime of CFC substitutes studied by a network trained with chaotic mapping modified genetic algorithm and DFT calculations.

    PubMed

    Lü, Q; Wu, H; Yu, R; Shen, G

    2004-08-01

    The hydrohaloalkanes have attracted much attention as potential substitutes of chlorofluorocarbons (CFCs) that deplete the ozone layer and lead to great high global warming. Having a short atmospheric lifetime is very important for the potential substitutes that may also induce ozone depletion and yield high global warming gases to be put in use. Quantitative structure-activity relationship (QSAR) studies were presented for their lifetimes aided by the quantum chemistry parameters including net charges, Mulliken overlaps, E(HOMO) and E(LUMO) based on the density functional theory (DFT) at B3PW91 level, and the C-H bond dissociation energy based on AM1 calculations. Outstanding features of the logistic mapping, a simple chaotic system, especially the inherent ability to search the space of interest exhaustively have been utilized. The chaotic mapping aided genetic algorithm artificial neural network training scheme (CGANN) showed better performance than the conventional genetic algorithm ANN training when the structure of the data set was not favorable. The lifetimes of HFCs and HCs appeared to be greatly dependent on their energies of the highest occupied molecular orbitals. The perference of the RMSRE comparing to RMSE as objective function of ANN training was better for the samples of interest with relatively short lifetimes. C(2)H(6) and C(3)H(8) as potential green substitutes of CFCs present relatively short lifetimes.

  5. Spin coherence time studies of a horizontally polarized deuteron beam at COSY

    NASA Astrophysics Data System (ADS)

    G Guidoboni JEDI Collaboration

    2015-11-01

    The measurement of a non-zero electric dipole moment (EDM) aligned along the spin of sub-atomic particles would probe new physics beyond the standard model. It has been proposed to search for the EDM of charged particles using a storage ring and a longitudinally polarized beam. The EDM signal would be a rotation of the polarization from the horizontal plane toward the vertical direction as a consequence of the radial electric field always present in the particle frame. This experiment requires ring conditions that can ensure a lifetime of the in-plane polarization (spin coherence time, SCT) up to 1000 s. A study has begun at the COoler SYnchrotron (COSY) located at the Forschungszentrum Jülich to examine the effects of emittance and momentum spread on the SCT of a polarized deuteron beam at 0.97 GeV c-1. A special Data AcQuisition has been developed in order to provide a direct measurement of a rapidly rotating horizontal polarization as a function of time. The set of data presented here shows how second-order effects from emittance and momentum spread of the beam affect the lifetime of the horizontal polarization of a bunched beam. It has been demonstrated that sextupole fields can be used to correct for these depolarizing sources and increase the SCT up to hundreds of seconds.

  6. Starspot lifetimes

    NASA Astrophysics Data System (ADS)

    Hussain, G. A. J.

    2002-07-01

    Photometry and Doppler imaging are both powerful techniques that can be used to evaluate the timescales of surface activity phenomena on active rapidly rotating objects. Active longitudes are most easily detected through photometry. These are found to have lifetimes of between 4-8 years. Many RSCVn binary systems and single stars show the ``flip-flop'' effect, where dominant spotted regions switch back and forth by 180deg longitude over a set number of years. Doppler imaging is most effective at evaluating the presence of polar spots and smaller scale spots in the mid to low latitude regions (up to 3deg resolution at the equator). This technique enables the monitoring of spot group lifetimes with greater accuracy than with photometry alone. Polar spots are found to have lifetimes of over a decade in RSCVn binary systems (V711 Tau & EI Eri) and in single MS stars, (AB Dor). In AB Dor, long-term photometry and Doppler imaging show that when the star was at its most spotted, there was no polar spot. Recent results indicate that surface shear was also suppressed in AB Dor at the same epoch. This implies that spot lifetimes can also be affected by changing surface shear rates over the course of an activity cycle. Mid to low latitude spots on single MS stars are found to have lifetimes of under 1 month. Spots in active components of RSCVn binaries show less modulation over a month compared to single MS rapid rotators. This indicates that either less flux is injected into the stellar surface over one month, or else that flux emergence is confined to small preferred regions in tidally locked systems. More long-term monitoring of these and other rapidly rotating systems using Doppler imaging, photometry and molecular band mapping using TiO and OH will enable us to evaluate whether or not these initial trends are representative of active cool stars.

  7. Rebuilding the Brookhaven high flux beam reactor: A feasibility study

    SciTech Connect

    Brynda, W.J.; Passell, L.; Rorer, D.C.

    1995-01-01

    After nearly thirty years of operation, Brookhaven`s High Flux Beam Reactor (HFBR) is still one of the world`s premier steady-state neutron sources. A major center for condensed matter studies, it currently supports fifteen separate beamlines conducting research in fields as diverse as crystallography, solid-state, nuclear and surface physics, polymer physics and structural biology and will very likely be able to do so for perhaps another decade. But beyond that point the HFBR will be running on borrowed time. Unless appropriate remedial action is taken, progressive radiation-induced embrittlement problems will eventually shut it down. Recognizing the HFBR`s value as a national scientific resource, members of the Laboratory`s scientific and reactor operations staffs began earlier this year to consider what could be done both to extend its useful life and to assure that it continues to provide state-of-the-art research facilities for the scientific community. This report summarizes the findings of that study. It addresses two basic issues: (i) identification and replacement of lifetime-limiting components and (ii) modifications and additions that could expand and enhance the reactor`s research capabilities.

  8. Beam dynamics studies for the relativistic klystron two-beam accelerator experiment

    NASA Astrophysics Data System (ADS)

    Lidia, Steven M.

    2001-04-01

    Two-beam accelerators (TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band \\(~8-12 GHz\\) through Ka-band \\(~30-35 GHz\\) frequency regions. The relativistic klystron two-beam accelerator project, whose aim is to study TBAs based upon extended relativistic klystrons, is described, and a new simulation code is used to design the latter portions of the experiment. Detailed, self-consistent calculations of the beam dynamics and of the rf cavity output are presented and discussed together with a beam line design that will generate nearly 1.2 GW of power from 40 rf cavities over a 10 m distance. The simulations show that beam current losses are acceptable and that longitudinal and transverse focusing techniques are sufficiently capable of maintaining a high degree of beam quality along the entire beam line.

  9. Simulations of beam-beam and beam-wire interactions in RHIC

    SciTech Connect

    Kim, Hyung J.; Sen, Tanaji; Abreu, Natalia P.; Fischer, Wolfram; /Brookhaven

    2009-02-01

    The beam-beam interaction is one of the dominant sources of emittance growth and luminosity lifetime deterioration. A current carrying wire has been proposed to compensate long-range beam-beam effects in the LHC and strong localized long-range beam-beam effects are experimentally investigated in the RHIC collider. Tune shift, beam transfer function, and beam loss rate are measured in dedicated experiments. In this paper, they report on simulations to study the effect of beam-wire interactions based on diffusive apertures, beam loss rates, and beam transfer function using a parallelized weak-strong beam simulation code (BBSIMC). The simulation results are compared with measurements performed in RHIC during 2007 and 2008.

  10. Fluorescence Lifetime Imaging and Intravascular Ultrasound: Co-Registration Study Using Ex Vivo Human Coronaries

    PubMed Central

    Gorpas, Dimitris; Fatakdawala, Hussain; Bec, Julien; Ma, Dinglong; Yankelevich, Diego R.; Qi, Jinyi

    2015-01-01

    Fluorescence lifetime imaging (FLIM) has demonstrated potential for robust assessment of atherosclerotic plaques biochemical composition and for complementing conventional intravascular ultrasound (IVUS), which provides information on plaque morphology. The success of such a bi-modal imaging modality depends on accurate segmentation of the IVUS images and proper angular registration between these two modalities. This paper reports a novel IVUS segmentation methodology addressing this issue. The image preprocessing consisted of denoising, using the Wiener filter, followed by image smoothing, implemented through the application of the alternating sequential filter on the edge separability metric images. Extraction of the lumen/intima and media/adventitia boundaries was achieved by tracing the gray-scale peaks over the A-lines of the IVUS preprocessed images. Cubic spline interpolation, in both cross-sectional and longitudinal directions, ensured boundary smoothness and continuity. The detection of the guide-wire artifact in both modalities is used for angular registration. Intraluminal studies were conducted in 13 ex vivo segments of human coronaries. The IVUS segmentation accuracy was assessed against independent manual tracings, providing 91.82% sensitivity and 97.55% specificity. The proposed methodology makes the bi-modal FLIM and IVUS approach feasible for comprehensive intravascular diagnosis by providing co-registered biochemical and morphological information of atherosclerotic plaques. PMID:25163056

  11. [Study of cancer cells fluorescence lifetime based on picosecond time resolution].

    PubMed

    Chen, Bi-Fang; Liu, Tian-Fu

    2006-08-01

    The object of the present study was the ultrafast photodynamic processes of hematoporphyrin derivative (HPD) for diagnosis and therapy of cancer. Time-resolved fluorescence spectra of cancerous and normal cells were measured using an ultrashort pulse laser spectral technique and picosecond time-correlated single-photon counting system. The fast part of cancerous and normal cells fluorescence decay was approximately 150 and 300 ps, the fluorescence peak intensity of cancerous and normal cells decayed about 10% and 55% in 12 hour, the lifetime of cancerous and normal cells was about 824 and 1 798 ps by calculating date of fluorescence decay, and HPD stay time was about 17 and 6 days in the cancerous and normal cells sample respectively. The data show that cancerous cells were greatly intimate with HPD. The results obtained can be used as an important basis for the diagnosis of cancer based on ultrashort pulse laser spectral technique. The results will contribute to feebleness ultrafast fluorescence of biology sample for real time measurement. PMID:17058959

  12. A Six-Wave Study of the Consistency of Mexican/Mexican American Preadolescents' Lifetime Substance Use Reports

    ERIC Educational Resources Information Center

    Wagstaff, David A.; Kulis, Stephen; Elek, Elvira

    2009-01-01

    In the Fall of 2004, 1,948 5th grade students from Phoenix, AZ enrolled in an evaluation of a school-based, substance use prevention intervention. To assess the consistency of Mexican and Mexican-American students' self-reports of lifetime substance use, the present study analyzed data reported by 1,418 students who reported Mexican ancestry and…

  13. Estimation of the lifetime of small helium bubbles near tungsten surfaces - A methodological study

    NASA Astrophysics Data System (ADS)

    Cui, Jiechao; Wu, Zhangwen; Hou, Qing

    2016-09-01

    Under low energy and high flux/fluence irradiation of helium (He) atoms, the formation and bursting of He bubbles on tungsten (W) surfaces play important roles in the morphological evolution of component surfaces in fusion reactors. Microscopically, the bursting of He bubbles is a stochastic process, and He bubbles have statistically average lifetimes. In the present paper, a molecular dynamics-based method was developed to extract, for the first time, the lifetime of He bubbles near tungsten surfaces. It was found that He bubble bursting can be treated as an activated event. Its frequency or, equivalently, the average lifetime of bubbles follows the Arrhenius equation. For a given bubble size, the activation energy exhibits a good linear dependence with the depth, and the pre-exponential factor obeys the Meyer-Neldle rule. These results are useful for establishing a model in multi-scale simulations of the morphological evolution of component surfaces in fusion reactors.

  14. Dynamic aperture study and lifetime improvement at the Advanced Photon Source.

    SciTech Connect

    Sajaev, V.; Emery, L.; Accelerator Systems Division

    2006-01-01

    Over the past few years, the optics of the Advanced Photon Source storage ring has been optimized to provide lower natural emittance. Presently, the APS operates at 2.5 nm-rad emittance. The optimization was done at the expense of stronger sextupoles and shorter lifetime. Here we present our work on measurement and understanding of the dynamic aperture of the APS in low-emittance mode. We found good agreement between the dynamic aperture measurements and that of the model derived from the response matrix analysis. Based on the model, we were able to increase the lifetime significantly by optimizing sextupoles, correcting optics, moving a working point, and adjusting rf voltage. The higher lifetime allowed us to decrease operating coupling from 2.5% to 1%.

  15. Antidepressant Use and Lifetime History of Mental Disorders in a Community Sample: Results from the Baltimore Epidemiologic Catchment Area Study

    PubMed Central

    Takayanagi, Yoichiro; Spira, Adam P.; Bienvenu, O. Joseph; Hock, Rebecca S.; Carras, Michelle C.; Eaton, William W.; Mojtabai, Ramin

    2015-01-01

    Objectives Past studies have shown that many individuals who use antidepressants do not have a current or lifetime history of mental disorders. However, recent studies suggest that the one-time retrospective evaluation of mental disorders commonly used in such studies may substantially underestimate the true lifetime prevalence of mental disorders. We examined the prevalence of mental disorders, assessed prospectively over multiple interviews, among individuals currently using antidepressants in a community sample. Methods Using data from the Baltimore Epidemiologic Catchment Area (ECA) Survey Wave 1 (1981) through Wave 4 (2004) (N = 1071), we assessed lifetime prevalence of common mood and anxiety disorders according to the DSM-III and DSM-III-R criteria, based on 4 interviews, among participants who reported current antidepressant use. Furthermore, we examined factors associated with current antidepressant use. Results Thirteen percent of participants at Wave 4 reported currently using antidepressant medications. Among antidepressant users, 69% never met criteria for major depressive disorder (MDD), and 38% never met criteria for MDD, obsessive-compulsive disorder, panic disorder, social phobia, or generalized anxiety disorder in their lifetime. Female gender, Caucasian ethnicity, recent or current physical problems (e.g., loss of bladder control, hypertension and back pain) and recent mental health facility visits were associated with antidepressant use in addition to mental disorders. Conclusions Many individuals who are prescribed and use antidepressant medications may not have met criteria for mental disorders. Our data indicate that antidepressants are commonly used in the absence of clear evidence-based indications. PMID:25188822

  16. Exploring lifetime occupational exposure and SLE flare: a patient-focussed pilot study

    PubMed Central

    Squance, Marline L; Guest, Maya; Reeves, Glenn; Attia, John; Bridgman, Howard

    2014-01-01

    Introduction Environmental effectors, such as ultraviolet radiation exposure, infection and stress, have been established as having a role in exacerbating lupus symptoms. However, unpredictable patterns of flare events still remain a mystery. Occupational effectors have also been suggested as having a contributing role; however, they are not widely researched. In this paper we report a pilot study designed to generate focus areas for future research regarding occupational exposures and systemic lupus erythematosus (SLE). Methods The study explored potential links between exposures and the occurrence of patient-reported flare events in 80 Australian women with SLE (American College of Rheumatology (ACR) criteria classified). Specifically, the study assessed the hypothesis that occupational exposure is associated with significant changes in the likelihood of lupus flares. Lifetime employment history was analysed with the Finnish Job Exposure Matrix (FINJEM), 40 different semiquantified exposure class estimates for a wide number of occupations based on probability of exposure (p≥5%=exposed) were analysed with the construction of negative binomial regression models to test relationships between occupational agents and flare days. A backward stepwise elimination was used to generate a parsimonious model. Results Significant associations were noted for exposure classes of manual handling burden, (p=0.02, incidence rate ratio (IRR) 1.01), Iron (p=0.00, IRR 1.37), wood dust (p=0.00, IRR 3.34) and asbestos (p=0.03, IRR 2.48). Conclusion Exposure assessment results indicated that occupations, such as nursing, with a high manual handling burden, posed increased risk to patients with SLE, however, the greatest risk was associated with wood dust and iron exposure with teachers and specialist labourers. PMID:25379190

  17. Lifetime (149-week) oral carcinogenicity study of vinyl chloride in rats.

    PubMed

    Til, H P; Feron, V J; Immel, H R

    1991-10-01

    A lifetime (149-wk) oral carcinogenicity study of vinyl chloride monomer (VCM) was carried out. Four groups of Wistar rats were used, each consisting of 100 males and 100 females, except for the high-dose group, which comprised 50 males and 50 females. VCM was administered by incorporating polyvinyl chloride powder with a high content of VCM into the diet. The actual exposure levels of VCM were 0 (control), 0.014, 0.13 and 1.3 mg VCM/kg body weight/day. Detailed histopathological examination was restricted to the liver. In the final stage of the study, the mortality in the high-dose group was slightly higher than in controls. A variety of VCM-related liver lesions was found in the high-dose group. The lesions included increased incidences of liver-cell polymorphism, hepatic cysts, foci of cellular alteration, neoplastic nodules, hepatocellular carcinomas and angiosarcomas. Compared with controls, there were increased incidences of hepatic foci of cellular alteration in females of the mid-dose group and of basophilic foci of hepatocellular alteration in females of both the low- and mid-dose groups. There was no evidence that feeding of VCM affected the incidence of tumours in organs other than the liver. Thus, the present study showed that the feeding of VCM at a level of 1.3 mg/kg body weight/day can induce neoplastic and non-neoplastic changes in the livers of male as well as female rats. The feeding of 0.014 or 0.13 mg VCM/kg body weight/day may result in an increased incidence of (basophilic) foci of cellular alteration in the liver of female rats. It was concluded that 0.13 mg VCM/kg body weight/day is the no-observed-adverse-effect level with respect to the induction of tumours in rats.

  18. Multi-particle weak-strong simulation of RHIC head-on beam-beam compensation.

    SciTech Connect

    Luo,Y.; Abreu, N.; Beebe-Wang, J.; FischW; Robert-Demolaize, G.

    2008-06-23

    To compensate the large tune spread generated by the beam-beam interactions in the polarized proton (pp) run in the Relativistic Heavy Ion Collider (RHIC), a low energy round Gaussian electron beam or electron lens is proposed to collide head-on with the proton beam. Using a weakstrong beam-beam interaction model, we carry out multiparticle simulations to investigate the effects of head-on beam-beam compensation on the proton beam's lifetime and emittance growth. The simplectic 6-D element-by-element tracking code SixTrack is adopted and modified for this study. The code benchmarking and preliminary simulation results are presented.

  19. Lifetime studies of security inks using a novel gonio-spectrometer with in situ aging capability

    NASA Astrophysics Data System (ADS)

    Emerich, Markus; Rosenberg, Erwin; Deinhammer, Harald; Paleczek, Susanne; Fajmann, Peter; Schwarzbach, Daniel

    2004-06-01

    The state of the art in manufacturing security documents includes the usage of a multitude of inks and pigments. The chemical and physical stability of these materials is a crucial point for their application in long lasting security products such as banknotes. For our studies regarding the bleaching characteristics of pigments and inks we have developed a highly integrated double beam gonio-spectrometer with in-situ ageing capability. The new spectrometer is equipped with a stabilized solar simulator lamp featuring a dosimeter, which is an advanced alternative to the commonly used blue wool scale. Additionally the sample temperature can be stabilized during ageing tests by a thermostatted sample holder. The instrument is capable of performing reflection measurements using monochromatic and polychromatic excitation and further allows fluorescence, phosphorescence and polarization measurements with high resolution over a wide wavelength range. We will present first results of defined ageing tests on a variety of security pigments and the setup of the newly developed spectrometer.

  20. Technology integration box beam failure study

    NASA Technical Reports Server (NTRS)

    Shuart, Mark J.; Ambur, D. R.; Davis, D. D., Jr.; Davis, Randall C.; Farley, G. L.; Lotts, C. G.; Wang, J. T.

    1992-01-01

    Composite structures have the potential to be cost effective, structurally efficient primary aircraft structures. As part of the Advanced Composite Technology (ACT) program to exploit this potential for heavily loaded aircraft structures, the design and fabrication of the technology integration box beam (TIBB) was completed. The TIBB is an advanced composite prototype structure for the center wing section of the Lockheed C-130 aircraft. The TIBB was tested for downbending, upbending, torsion, and combined upbending and torsion load conditions to verify the design. The TIBB failed at 83 percent of design ultimate load for the combined upbending and torsion load condition. Current analytical and experimental results are described for a study of the mechanisms that led to the failure of the TIBB. Experimental results include load, strain, and deflection data. An analytical study was conducted of the TIBB structural response. Analytical results include strain and deflection results from a global analysis of the TIBB.

  1. Studies of Ion Beam Charge Neutralization by Ferroelectric Plasma Sources

    NASA Astrophysics Data System (ADS)

    Stepanov, A.; Gilson, E. P.; Grisham, L.; Davidson, R. C.

    2013-10-01

    Space-charge forces limit the possible transverse compression of high perveance ion beams that are used in ion-beam-driven high energy density physics applications; the minimum radius to which a beam can be focused is an increasing function of perveance. The limit can be overcome if a plasma is introduced in the beam path between the focusing element and the target in order to neutralize the space charge of the beam. This concept has been implemented on the Neutralized Drift Compression eXperiment (NDCX) at LBNL using Ferroelectric Plasma Sources (FEPS). In our experiment at PPPL, we propagate a perveance-dominated ion beam through a FEPS to study the effect of the neutralizing plasma on the beam envelope and its evolution in time. A 30-60 keV space-charge-dominated Argon beam is focused with an Einzel lens into a FEPS located at the beam waist. The beam is intercepted downstream from the FEPS by a movable Faraday cup that provides time-resolved 2D current density profiles of the beam spot on target. We report results on: (a) dependence of charge neutralization on FEPS plasma density; (b) effects on beam emittance, and (c) time evolution of the beam envelope after the FEPS pulse. Research supported by the U.S. Department of Energy.

  2. Lifetime medical and psychiatric comorbidity of night eating behavior in the Swedish Twin Study of Adults: Genes and Environment (STAGE).

    PubMed

    Lundgren, Jennifer D; Allison, Kelly C; Stunkard, Albert J; Bulik, Cynthia M; Thornton, Laura M; Karin Lindroos, Anna; Rasmussen, Finn

    2012-09-30

    The medical and psychosocial comorbidity of two core features of night eating syndrome (NES), evening hyperphagia (EH) and nocturnal awakening and ingestion of food (NI), was evaluated in adults enrolled in the Swedish Twin Study of Adults: Genes and Environment (STAGE) study. As part of the STAGE study, more than 20,000 participants completed assessments of their physical and mental health, which included two night eating screening questions designed to assess EH and NI. STAGE participants who completed a night eating validation interview to confirm the presence or absence of night eating and who had comorbidity data available (n=463) were compared on the lifetime prevalence of several psychiatric and medical conditions. In contrast to previous studies, night eating (EH and/or NI) was not significantly associated with lifetime history of any mental or physical health variable.

  3. Lifetime medical and psychiatric comorbidity of night eating behavior in the Swedish Twin Study of Adults: Genes and Environment (STAGE).

    PubMed

    Lundgren, Jennifer D; Allison, Kelly C; Stunkard, Albert J; Bulik, Cynthia M; Thornton, Laura M; Karin Lindroos, Anna; Rasmussen, Finn

    2012-09-30

    The medical and psychosocial comorbidity of two core features of night eating syndrome (NES), evening hyperphagia (EH) and nocturnal awakening and ingestion of food (NI), was evaluated in adults enrolled in the Swedish Twin Study of Adults: Genes and Environment (STAGE) study. As part of the STAGE study, more than 20,000 participants completed assessments of their physical and mental health, which included two night eating screening questions designed to assess EH and NI. STAGE participants who completed a night eating validation interview to confirm the presence or absence of night eating and who had comorbidity data available (n=463) were compared on the lifetime prevalence of several psychiatric and medical conditions. In contrast to previous studies, night eating (EH and/or NI) was not significantly associated with lifetime history of any mental or physical health variable. PMID:22560060

  4. Positron and positronium annihilation in silica-based thin films studied by a pulsed positron beam

    NASA Astrophysics Data System (ADS)

    Suzuki, R.; Ohdaira, T.; Kobayashi, Y.; Ito, K.; Shioya, Y.; Ishimaru, T.

    2003-10-01

    Positron and positronium annihilation in silica-based thin films has been investigated by means of measurement techniques with a monoenergetic pulsed positron beam. The age-momentum correlation study revealed that positron annihilation in thermally grown SiO 2 is basically the same as that in bulk amorphous SiO 2 while o-Ps in the PECVD grown SiCOH film predominantly annihilate with electrons of C and H at the microvoid surfaces. We also discuss time-dependent three-gamma annihilation in porous low- k films by two-dimensional positron annihilation lifetime spectroscopy.

  5. Studies of 3He polarization losses during NMR and EPR measurment and Polarized 3He target cell lifetime

    NASA Astrophysics Data System (ADS)

    An, Peibo

    2014-09-01

    The 3He target cell polarized by spin-exchange optical pumping(SEOP) is used as a neutron substitute to study the inner structure of the neutron. In our lab, nuclear-magnetic-resonance(NMR) is used to measure the relative polarization and electron-paramagnetic-resonance(EPR) is used to measure the spin exchange EPR frequency shift parameter of potassium and rubidium in our target cell presented in magnetic fields. The alkali in the cell is used to facilitate the polarization of 3He. The first part of my work presents the study of the polarization losses of the cell during both NMR and EPR. With the help of improved RF coils, we keep the background noise received by pickup coils reasonably low, but three other kinds of losses are inevitable: losses during Adiabatic Fast Passage (AFP) sweep, losses due to flux change caused by different cell orientation with respect to RF fields and physical losses. Fortunately there is only flux change in NMR measurements. The second part of my work presents the study of cell lifetime improvement. The polarization decreases in a process called relaxation exponentially. The lifetime of a cell is how long it can keep its polarization. The typical lifetime of cells produced in our lab is about 22 hours. With a newly designed vacuum system. The 3He target cell polarized by spin-exchange optical pumping(SEOP) is used as a neutron substitute to study the inner structure of the neutron. In our lab, nuclear-magnetic-resonance(NMR) is used to measure the relative polarization and electron-paramagnetic-resonance(EPR) is used to measure the spin exchange EPR frequency shift parameter of potassium and rubidium in our target cell presented in magnetic fields. The alkali in the cell is used to facilitate the polarization of 3He. The first part of my work presents the study of the polarization losses of the cell during both NMR and EPR. With the help of improved RF coils, we keep the background noise received by pickup coils reasonably low, but

  6. Feasibility study for mega-electron-volt electron beam tomography

    SciTech Connect

    Hampel, U.; Baertling, Y.; Hoppe, D.; Kuksanov, N.; Fadeev, S.; Salimov, R.

    2012-09-15

    Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

  7. Feasibility study for mega-electron-volt electron beam tomography.

    PubMed

    Hampel, U; Bärtling, Y; Hoppe, D; Kuksanov, N; Fadeev, S; Salimov, R

    2012-09-01

    Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

  8. Pinhole shifting lifetime imaging microscopy.

    PubMed

    Ramshesh, Venkat K; Lemasters, John J

    2008-01-01

    Lifetime imaging microscopy is a powerful tool to probe biological phenomena independent of luminescence intensity and fluorophore concentration. We describe time-resolved imaging of long-lifetime luminescence with an unmodified commercial laser scanning confocal/multiphoton microscope. The principle of the measurement is displacement of the detection pinhole to collect delayed luminescence from a position lagging the rasting laser beam. As proof of principle, luminescence from microspheres containing europium (Eu(3+)), a red emitting probe, was compared to that of short-lifetime green-fluorescing microspheres and/or fluorescein and rhodamine in solution. Using 720-nm two-photon excitation and a pinhole diameter of 1 Airy unit, the short-lifetime fluorescence of fluorescein, rhodamine and green microspheres disappeared much more rapidly than the long-lifetime phosphorescence of Eu(3+) microspheres as the pinhole was repositioned in the lagging direction. In contrast, repositioning of the pinhole in the leading and orthogonal directions caused equal loss of short- and long-lifetime luminescence. From measurements at different lag pinhole positions, a lifetime of 270 micros was estimated for the Eu(3+) microspheres, consistent with independent measurements. This simple adaptation is the basis for quantitative 3-D lifetime imaging microscopy. PMID:19123648

  9. Fast beam studies of free radical photodissociation

    SciTech Connect

    Neumark, D.M.

    1993-12-01

    The authors have developed a novel technique for studying the photodissociation spectroscopy and dynamics of free radicals. In these experiments, radicals are generated by laser photodetachment of a fast (6-8 keV) mass-selected negative ion beam. The resulting radicals are photodissociated with a second laser, and the photofragments are collected and detected with high efficiency using a microchannel plate detector. The overall process is: ABC{sup -} {yields} ABC + e{sup -} {yields} A + BC, AB + C. Two types of fragment detection schemes are used. To map out the photodissociation cross-section of the radical, the photodissociation laser is scanned and the total photofragment yield is measured as a function of wavelength. In other experiments, the photodissociation frequency is fixed and the photofragment masses, kinetic energy release, and scattering angle is determined for each photodissociation event.

  10. Multiple beam antenna/switch system study

    NASA Technical Reports Server (NTRS)

    1989-01-01

    In the study of the Multiple Beam Antenna/Switch for the space to ground link (SGL) uplink and downlink services, several issues related to system engineering, antenna, transmit/receive, and switch systems were addressed and the results are provided. Bandwidth allocation at Ku band is inadequate to serve the data rate requirements for the forward and return services. Rain and depolarization effects at EHF, especially at Ka band, pose a significant threat to the link availabilities at heavy rain areas. Hardware induced effects such as the nonlinear characteristics of the power amplifier may necessitate the use of linearizers and limiters. It is also important to identify the components that are susceptible to the space radiation effects and shield or redesign them with rad-hard technologies for meeting the requirements of the space environment.

  11. Study of excitation transfer in laser dye mixtures by direct measurement of fluorescence lifetime

    NASA Technical Reports Server (NTRS)

    Lin, C.; Dienes, A.

    1973-01-01

    By directly measuring the donor fluorescence lifetime as a function of acceptor concentration in the laser dye mixture Rhodamine 6G-Cresyl violet, we found that the Stern-Volmer relation is obeyed, from which the rate of excitation transfer is determined. The experimental results indicate that the dominant mechanism responsible for the efficient excitation transfer is that of resonance transfer due to long range dipole-dipole interaction.

  12. Molecular beam studies of stratospheric photochemistry

    NASA Astrophysics Data System (ADS)

    Moore, Teresa Anne

    1998-12-01

    Photochemistry of chlorine oxide containing species plays a major role in stratospheric ozone depletion. This thesis discusses two photodissociation studies of the key molecules ClONO2 and ClOOCl which were previously thought to only produce Cl-atom (ozone depleting) products at wavelengths relevant to the stratosphere. The development of a molecular beam source of ClOOCl and the photodissociation dynamics of the model system Cl2O are also discussed. In the first chapter, the photochemistry of ClONO2 is examined at 308 nm using the technique of photofragment translational spectroscopy. Two primary decomposition pathways, leading to Cl + NO3 and ClO + NO2, were observed, with a lower limit of 0.33 for the relative yield of ClO. The angular distributions for both channels were anisotropic, indicating that the dissociation occurs within a rotational period. Chapter two revisits the photodissociation dynamics of Cl2O at 248 and 308 nm, on which we had previously reported preliminary findings. At 248 nm, three distinct dissociation pathways leading to Cl + ClO products were resolved. At 308 nm, the angular distribution was slightly more isotropic that previously reported, leaving open the possibility that Cl2O excited at 308 nm lives longer than a rotational period. Chapter three describes the development and optimization of a molecular beam source of ClOOCl. We utilized pulsed laser photolysis of ClA2O to generate ClO radicals, and cooled the cell to promote three body recombination to form ClOOCl. The principal components in the beam were Cl2, Cl2O, and ClOOCl. In the fourth chapter, the photodissociation dynamics of ClOOCl are investigated at 248 and 308 nm. We observed multiple dissociation pathways which produced ClO + ClO and 2Cl + O2 products. The relative Cl:ClO product yields are 1.0:0.13 and 1.0:0.20 for ClOOCl photolysis at 248 and 308 nm, respectively. The upper limit for the relative yield of the ClO + ClO channel was 0.19 at 248 nm and 0.31 at 308 nm

  13. Experimental demonstration of beam-beam compensation by Tevatron electron lenses and prospects for the LHC

    SciTech Connect

    Shiltsev, V.; Alexahin, Y.; Kamerdzhiev, V.; Kuznetsov, G.; Zhang, X.L.; Bishofberger, K.; /Los Alamos

    2007-06-01

    Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams are significant sources of beam loss and lifetime limitations in the Tevatron Collider Run II (2001-present). We present observations of the beam-beam phenomena in the Tevatron and results of relevant beam studies. We analyze the data and various methods employed in high energy physics (HEP) operation, predict the performance for planned luminosity upgrades and discuss ways to improve it.

  14. Study on space charge compensation in negative hydrogen ion beam.

    PubMed

    Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E

    2016-02-01

    Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results. PMID:26932087

  15. Study on space charge compensation in negative hydrogen ion beam.

    PubMed

    Zhang, A L; Peng, S X; Ren, H T; Zhang, T; Zhang, J F; Xu, Y; Guo, Z Y; Chen, J E

    2016-02-01

    Negative hydrogen ion beam can be compensated by the trapping of ions into the beam potential. When the beam propagates through a neutral gas, these ions arise due to gas ionization by the beam ions. However, the high neutral gas pressure may cause serious negative hydrogen ion beam loss, while low neutral gas pressure may lead to ion-ion instability and decompensation. To better understand the space charge compensation processes within a negative hydrogen beam, experimental study and numerical simulation were carried out at Peking University (PKU). The simulation code for negative hydrogen ion beam is improved from a 2D particle-in-cell-Monte Carlo collision code which has been successfully applied to H(+) beam compensated with Ar gas. Impacts among ions, electrons, and neutral gases in negative hydrogen beam compensation processes are carefully treated. The results of the beam simulations were compared with current and emittance measurements of an H(-) beam from a 2.45 GHz microwave driven H(-) ion source in PKU. Compensation gas was injected directly into the beam transport region to modify the space charge compensation degree. The experimental results were in good agreement with the simulation results.

  16. Beam Dynamics Simulation Platform and Studies of Beam Breakup in Dielectric Wakefield Structures

    SciTech Connect

    Schoessow, P.; Kanareykin, A.; Jing, C.; Kustov, A.; Altmark, A.; Gai, W.

    2010-11-04

    A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects is incorporated into a parallel computing framework based on the Boinc software environment, and supports both task farming on a heterogeneous cluster and local grid computing. User access to the platform is through a web browser.

  17. Positron lifetime studies of decomposition in 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) alloys

    SciTech Connect

    Dlubek, G. |; Lademann, P.; Krause, H.; Krause, S.; Unger, R.

    1998-09-04

    In the current paper, the decomposition behavior of the engineering alloys 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) is studied using positron lifetime measurements. Positrons probe open volume defects such as vacancies and dislocations. However, they may also be used to investigate coherent zones and incoherent precipitates. In order to understand the rather complicated precipitation sequences and the response of positrons to different type of precipitates occurring in 2024 and 7010 alloys, binary and ternary laboratory alloys were also investigated under the same experimental conditions as the engineering alloys. The interpretations of the results are based on experiences of the group from extensive positron studies of laboratory alloys such as Al-Zn, Al-Zn-Mg, Al-Cu, and further Al alloys (see also the review (4)). Their collected results are shown as lifetimes and curve-shape parameters S of the electron-positron momentum distribution curves characteristic for different precipitates in Al alloys.

  18. Study of a non-intrusive electron beam radius diagnostic

    SciTech Connect

    Kwan, T.J.T.; DeVolder, B.G.; Goldstein, J.C.; Snell, C.M.

    1997-12-01

    The authors have evaluated the usefulness and limitation of a non-intrusive beam radius diagnostic which is based on the measurement of the magnetic moment of a high-current electron beam in an axisymmetric focusing magnetic field, and relates the beam root-mean-square (RMS) radius to the change in magnetic flux through a diamagnetic loop encircling the beam. An analytic formula that gives the RMS radius of the electron beam at a given axial position and a given time is derived and compared with results from a 2-D particle-in-cell code. The study has established criteria for its validity and optimal applications.

  19. SU-E-T-304: Study of Secondary Neutrons From Uniform Scanning Proton Beams

    SciTech Connect

    Islam, M; Zheng, Y; Benton, E

    2014-06-01

    Purpose: Secondary neutrons are unwanted byproducts from proton therapy and exposure from secondary radiation during treatment could increase risk of developing a secondary cancer later in a patient's lifetime. The purpose of this study is to investigate secondary neutrons from uniform scanning proton beams under various beam conditions using both measurements and Monte Carlo simulations. Methods: CR-39 Plastic Track Nuclear Detectors (PNTD) were used for the measurement. CR-39 PNTD has tissue like sensitivity to the secondary neutrons but insensitive to the therapeutic protons. In this study, we devised two experimental conditions: a) hollow-phantom; phantom is bored with a hollow cylinder along the direction of the beam so that the primary proton passes through the phantom without interacting with the phantom material, b) cylindrical-phantom; a solid cylinder of diameter close to the beam diameter is placed along the beam path. CR-39 PNTDs were placed laterally inside a 60X20X35 cm3 phantom (hollow-phantom) and in air (cylindrical-phantom) at various angles with respect to the primary beam axis. We studied for three different proton energies (78 MeV, 162 MeV and 226 MeV), using a 4 cm modulation width and 5cm diameter brass aperture for the entire experiment and simulation. A comparison of the experiment was performed using the Monte Carlo code FLUKA. Results: The measured secondary neutron dose equivalent per therapeutic primary proton dose (H/D) ranges from 2.1 ± 0.2 to 25.42 ± 2.3 mSv/Gy for the hollow phantom study, and 2.7 ± 0.3 to 46.4 ± 3.4 mSv/Gy for the cylindrical phantom study. Monte Carlo simulations predicated neutron dose equivalent from measurements within a factor of 5. Conclusion: The study suggests that the production of external neutrons is significantly higher than the production of internal neutrons.

  20. Measurement requirements and techniques for degradation studies and lifetime prediction testing of photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Noel, G. T.; Sliemers, F. A.; Derringer, G. C.; Wood, V. E.; Wilkes, K. E.; Gaines, G. B.; Carmichael, D. C.

    1978-01-01

    Tests of weathering and aging behavior are being developed to characterize the degradation and predict the lifetimes of low-cost photovoltaic arrays. Environmental factors which affect array performance include UV radiation, thermal energy, water, oxygen (generally involved in synergistic effects with UV radiation or high temperatures), physical stress, pollutants (oxides of nitrogen, sulfur dioxide and ozone), abrasives and dirt. A survey of photovoltaic array testing has shown the need to establish quantitative correlations between certain measurable properties (carbonyl formation, glass transition temperature, and molecular weight change) and modes of degradation and failure.

  1. Lifetime studies in H/sub 2//Br/sub 2/ fuel cells

    SciTech Connect

    Barna, G.G.; Frank, S.N.; Teherani, T.H.; Weedon, L.D.

    1984-09-01

    A fully computerized system has been set up for the life testing of H/sub 2/ electrodes in 48% HBr, and of H/sub 2//Br/sub 2/ fuel cells. Given a fuel cell design with dry H/sub 2/ and no anolyte loop, the prime parameters influencing the operating lifetime are the hydrophobicity of the anode and the electrolyte transport property of the membrane. A systematic optimization of all the parameters has generated fuel cells that have operated for 10,000h at 2 A/in./sup 2/, with no significant degradation.

  2. Parametric study of transport beam lines for electron beams accelerated by laser-plasma interaction

    NASA Astrophysics Data System (ADS)

    Scisciò, M.; Lancia, L.; Migliorati, M.; Mostacci, A.; Palumbo, L.; Papaphilippou, Y.; Antici, P.

    2016-03-01

    In the last decade, laser-plasma acceleration of high-energy electrons has attracted strong attention in different fields. Electrons with maximum energies in the GeV range can be laser-accelerated within a few cm using multi-hundreds terawatt (TW) lasers, yielding to very high beam currents at the source (electron bunches with up to tens-hundreds of pC in a few fs). While initially the challenge was to increase the maximum achievable electron energy, today strong effort is put in the control and usability of these laser-generated beams that still lack of some features in order to be used for applications where currently conventional, radio-frequency (RF) based, electron beam lines represent the most common and efficient solution. Several improvements have been suggested for this purpose, some of them acting directly on the plasma source, some using beam shaping tools located downstream. Concerning the latter, several studies have suggested the use of conventional accelerator magnetic devices (such as quadrupoles and solenoids) as an easy implementable solution when the laser-plasma accelerated beam requires optimization. In this paper, we report on a parametric study related to the transport of electron beams accelerated by laser-plasma interaction, using conventional accelerator elements and tools. We focus on both, high energy electron beams in the GeV range, as produced on petawatt (PW) class laser systems, and on lower energy electron beams in the hundreds of MeV range, as nowadays routinely obtained on commercially available multi-hundred TW laser systems. For both scenarios, our study allows understanding what are the crucial parameters that enable laser-plasma accelerators to compete with conventional ones and allow for a beam transport. We show that suitable working points require a tradeoff-combination between low beam divergence and narrow energy spread.

  3. Technology integration box beam failure study

    NASA Technical Reports Server (NTRS)

    Shuart, Mark J.; Ambur, Damodar R.; Davis, D. D., Jr.; Davis, R. C.; Farley, G. L.; Lotts, C. G.; Wang, J. T.

    1992-01-01

    The objective of this paper is to describe current results from an on-going study of the mechanisms that led to the failure of the TIBB. Experimental and analytical results are presented. Experimental results include load, strain, and deflection data for the TIBB (Technology Integration Box Beam). An analytical investigation was conducted to compliment the experimental investigation and to gain additional insight into the TIBB structural response. Analytical results include strain and deflection results from a global analysis of the TIBB. A local analysis of the failure region is being completed. These analytical results are validated through comparisons with the experimental results from the TIBB tests. The experimental and analytical results from the TIBB tests are used to determine a sequence of events that may have resulted in failure of the TIBB. A potential cause of failure is high stresses in a stiffener runout region. Typical analytical results are presented for a stiffener runout specimen that is being defined to simulate the TIBB failure mechanisms. The results of this study are anticipated to provide better understanding of potential failure mechanisms in composite aircraft structures, to lead to future design improvements, and to identify needed analytical tools for design and analysis.

  4. Beam dynamics studies for the relativistic klystron two-beam accelerator experiment

    SciTech Connect

    Lidia, Steven M.

    2001-06-22

    Two-beam accelerators based upon relativistic klystron s (RK s) have been proposed as power sources for future generation linear electron-positron colliders. These drivers are known to suffer from several transverse beam break-up (BBU) instabilities. A program to study a particular technique (the betatron node scheme ) for ameliorating the high frequency BBU is under way at LBNL. Central to this study are the pillbox RF cavities and RF beam position monitors (BPM s) employed. This paper describes the design, fabrication, and testing of the RF components. Performance details during operation are also discussed.

  5. Studying biological tissue with fluorescence lifetime imaging: microscopy, endoscopy, and complex decay profiles.

    PubMed

    Siegel, Jan; Elson, Daniel S; Webb, Stephen E D; Lee, K C Benny; Vlandas, Alexis; Gambaruto, Giovanni L; Lévêque-Fort, Sandrine; Lever, M John; Tadrous, Paul J; Stamp, Gordon W H; Wallace, Andrew L; Sandison, Ann; Watson, Tim F; Alvarez, Fernando; French, Paul M W

    2003-06-01

    We have applied fluorescence lifetime imaging (FLIM) to the autofluorescence of different kinds of biological tissue in vitro, including animal tissue sections and knee joints as well as human teeth, obtaining two-dimensional maps with functional contrast. We find that fluorescence decay profiles of biological tissue are well described by the stretched exponential function (StrEF), which can represent the complex nature of tissue. The StrEF yields a continuous distribution of fluorescence lifetimes, which can be extracted with an inverse Laplace transformation, and additional information is provided by the width of the distribution. Our experimental results from FLIM microscopy in combination with the StrEF analysis indicate that this technique is ready for clinical deployment, including portability that is through the use of a compact picosecond diode laser as the excitation source. The results obtained with our FLIM endoscope successfully demonstrated the viability of this modality, though they need further optimization. We expect a custom-designed endoscope with optimized illumination and detection efficiencies to provide significantly improved performance.

  6. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Y.T.

    1993-12-01

    The major thrust of this research project is to elucidate detailed dynamics of simple elementary reactions that are theoretically important and to unravel the mechanism of complex chemical reactions or photochemical processes that play important roles in many macroscopic processes. Molecular beams of reactants are used to study individual reactive encounters between molecules or to monitor photodissociation events in a collision-free environment. Most of the information is derived from measurement of the product fragment energy, angular, and state distributions. Recent activities are centered on the mechanisms of elementary chemical reactions involving oxygen atoms with unsaturated hydrocarbons, the dynamics of endothermic substitution reactions, the dependence of the chemical reactivity of electronically excited atoms on the alignment of excited orbitals, the primary photochemical processes of polyatomic molecules, intramolecular energy transfer of chemically activated and locally excited molecules, the energetics of free radicals that are important to combustion processes, the infrared-absorption spectra of carbonium ions and hydrated hydronium ions, and bond-selective photodissociation through electric excitation.

  7. Technology integration box beam failure study

    NASA Technical Reports Server (NTRS)

    Shuart, M. J.; Ambur, Damodar R.; Davis, D. D., Jr.; Davis, R. C.; Farley, G. L.; Lotts, C. G.; Wang, J. T.

    1993-01-01

    Composite structures have the potential to be cost-effective, structurally efficient primary aircraft structures. The Advanced Composites Technology (ACT) Program has the goal to develop the technology to exploit this potential for heavily loaded aircraft structures. As part of the ACT Program, Lockheed Aeronautical Systems Company completed the design and fabrication of the Technology Integration Box Beam (TIBB). The TIBB is an advanced composite prototype structure for the center wing section of the C-130 aircraft. Lockheed subjected the TIBB to downbending, upbending, torsion and combined upbending and torsion load conditions to verify the design. The TIBB failed at 83 percent of design ultimate load for the combined upbending and torsion load condition. The objective of this paper is to describe the mechanisms that led to the failure of the TIBB. The results of a comprehensive analytical and experimental study are presented. Analytical results include strain and deflection results from both a global analysis of the TIBB and a local analysis of the failure region. These analytical results are validated by experimental results from the TIBB tests. The analytical and experimental results from the TIBB tests are used to determine a sequence of events that resulted in failure of the TIBB. A potential cause of failure is high stresses in a stiffener runout region. Analytical and experimental results are also presented for a stiffener runout specimen that was used to simulate the TIBB failure mechanisms.

  8. Recent study of beam stability in the PSR

    NASA Astrophysics Data System (ADS)

    Wang, T. S. F.; Cooper, R.; Fitzgerald, D.; Frankle, S.; Hardek, T.; Hutson, R.; Macek, R.; Ohmori, C.; Plum, M.; Thiessen, H.

    1993-05-01

    A fast transverse instability with beam loss has been observed in the 800 MeV Los Alamos Pro Ring (PSR) when the injected beam intensity reaches 2 - 4(10)(exp 13) protons per pulse. Previous observations indicate that the instability is most likely driven by electrons trapped within the proton beam. Theoretical study shown that beam leakage into the inter-bunch gap leads to electron trapping. Recent experiments were carried out by using the newly implemented 'pinger' and by varying the machine transition gamma to explore further the 'e-p' instability and the nature of the instability. This paper summarizes some of these recent experimental results and theoretical studies.

  9. Recent study of beam stability in the PSR

    SciTech Connect

    Wang, T.S.F.; Cooper, R.; Fitzgerald, D.; Frankle, S.; Hardek, T.; Hutson, R.; Macek, R.; Ohmori, C.; Plum, M.; Thiessen, H.; Wilkinson, C.; Colton, E.; Neuffer, D.; Rees, G.

    1993-06-01

    A fast transverse instability with beam loss has been observed in the 800 MeV Los Alamos Pro Ring (PSR) when the injected beam intensity reaches 2 - 4 {times} 10{sup 13} protons per pulse. Previous observations in that the instability is most likely driven by electrons trapped within the proton beam. Theoretical study shown that beam leakage into the inter-bunch gap leads to electron trapping. Recent experiments were carried out by using the newly implemented ``pinger`` and by varying the machine transition gamma to explore further the ``e-p`` instability and the nature of the instability. This paper summarizes some of these recent experimental results and theoretical studies.

  10. Recent study of beam stability in the PSR

    SciTech Connect

    Wang, T.S.F.; Cooper, R.; Fitzgerald, D.; Frankle, S.; Hardek, T.; Hutson, R.; Macek, R.; Ohmori, C.; Plum, M.; Thiessen, H.; Wilkinson, C. ); Colton, E. ); Neuffer, D. ); Rees, G. )

    1993-01-01

    A fast transverse instability with beam loss has been observed in the 800 MeV Los Alamos Pro Ring (PSR) when the injected beam intensity reaches 2 - 4 [times] 10[sup 13] protons per pulse. Previous observations in that the instability is most likely driven by electrons trapped within the proton beam. Theoretical study shown that beam leakage into the inter-bunch gap leads to electron trapping. Recent experiments were carried out by using the newly implemented pinger'' and by varying the machine transition gamma to explore further the e-p'' instability and the nature of the instability. This paper summarizes some of these recent experimental results and theoretical studies.

  11. Molecular beam studies of oxygen atom reactions with unsaturated hydrocarbons

    SciTech Connect

    Schmoltner, A.-M.

    1989-10-01

    The dynamics of several elementary reactions relevant to combustion was investigated. The reactive scattering of ground state oxygen atoms with small unsaturated hydrocarbons was studied using a crossed molecular beam apparatus with a rotatable mass spectrometer detector. The infrared and ultraviolet photodissociation of anisole was studied using a rotating beam source/fixed detector apparatus. 253 refs., 64 figs., 4 tabs.

  12. Simulation of the beam halo from the beam-beam interaction in LEP

    SciTech Connect

    Chen, T.; Irwin, J.; Siemann, R.

    1994-02-01

    The luminosity lifetimes of e{sup +}e{sup {minus}} colliders are often dominated by the halo produced by the beam-beam interaction. They have developed a simulation technique to model this halo using the flux across boundaries in amplitude space to decrease the CPU time by a factor of one-hundred or more over `brute force` tracking. It allows simulation of density distributions and halos corresponding to realistic lifetimes. Reference 1 shows the agreement with brute force tracking in a number of cases and the importance of beam-beam resonances in determining the density distribution of large amplitudes. this research is now directed towards comparisons with operating colliders and studies of the combined effects of lattice and beam-beam nonlinearities. LEP offers an ideal opportunity for both, and in this paper they are presenting the first results of LEP simulations.

  13. Study of behavior and determination of customer lifetime value(CLV) using Markov chain model

    NASA Astrophysics Data System (ADS)

    Permana, Dony; Indratno, Sapto Wahyu; Pasaribu, Udjianna S.

    2014-03-01

    Customer Lifetime Value or CLV is a restriction on interactive marketing to help a company in arranging financial for the marketing of new customer acquisition and customer retention. Additionally CLV can be able to segment customers for financial arrangements. Stochastic models for the fairly new CLV used a Markov chain. In this model customer retention probability and new customer acquisition probability play an important role. This model is originally introduced by Pfeifer and Carraway in 2000 [1]. They introduced several CLV models, one of them only involves customer and former customer. In this paper we expand the model by adding the assumption of the transition from former customer to customer. In the proposed model, the CLV value is higher than the CLV value obtained by Pfeifer and Caraway model. But our model still requires a longer convergence time.

  14. Study of behavior and determination of customer lifetime value(CLV) using Markov chain model

    SciTech Connect

    Permana, Dony; Indratno, Sapto Wahyu; Pasaribu, Udjianna S.

    2014-03-24

    Customer Lifetime Value or CLV is a restriction on interactive marketing to help a company in arranging financial for the marketing of new customer acquisition and customer retention. Additionally CLV can be able to segment customers for financial arrangements. Stochastic models for the fairly new CLV used a Markov chain. In this model customer retention probability and new customer acquisition probability play an important role. This model is originally introduced by Pfeifer and Carraway in 2000 [1]. They introduced several CLV models, one of them only involves customer and former customer. In this paper we expand the model by adding the assumption of the transition from former customer to customer. In the proposed model, the CLV value is higher than the CLV value obtained by Pfeifer and Caraway model. But our model still requires a longer convergence time.

  15. A comparative study of the stress-rupture lifetimes of high-strength carbon fibers

    NASA Astrophysics Data System (ADS)

    Grimes-Ledesma, Lorie

    Stress-rupture life is the time a composite can survive under load at an assigned risk level. The stress-rupture lifetimes of high-strength PAN-based carbon fibers are important to the development and use of lightweight composite structures such as composite overwrapped pressure vessels (COPVs). To quantify appropriate stress-rupture risk levels based on available models, quantification of single fiber variability and lifetime is necessary to understand the variability observed in larger composite structures. In the present work, three PAN-based carbon fibers commonly used in COPV technology were examined, Hexcel IM9, Toray T700, and Toray T1000. The diameter of each fiber type was quantified by measuring samples in the scanning electron microscope and failure loads were determined by performing tensile tests on single fibers. Weibull statistics were used to describe the results. Fractography was performed on IM9 and T1000 fibers after tensile failure. The fracture surfaces are consistent with crack growth from a volume or surface defect. Stress-rupture testing was completed at two stress levels at each fiber type, 97% and 93% of the mean fiber strength for each of the fiber types. The results indicate that differences in stress-rupture life performance exist between the three fiber types. Differences in stress ratio of between 5 and 10% were observed, which may translate to significant difference in stress-rupture life behavior for larger composite structures. The results indicate that a relationship may exist between strength and stress-rupture life. However, if this relationship exists, it is not a simple one, and the relationship is likely complicated by manufacturing.

  16. Numerical study of neutron beam divergence in a beam-fusion scenario employing laser driven ions

    NASA Astrophysics Data System (ADS)

    Alejo, A.; Green, A.; Ahmed, H.; Robinson, A. P. L.; Cerchez, M.; Clarke, R.; Doria, D.; Dorkings, S.; Fernandez, J.; McKenna, P.; Mirfayzi, S. R.; Naughton, K.; Neely, D.; Norreys, P.; Peth, C.; Powell, H.; Ruiz, J. A.; Swain, J.; Willi, O.; Borghesi, M.; Kar, S.

    2016-09-01

    The most established route to create a laser-based neutron source is by employing laser accelerated, low atomic-number ions in fusion reactions. In addition to the high reaction cross-sections at moderate energies of the projectile ions, the anisotropy in neutron emission is another important feature of beam-fusion reactions. Using a simple numerical model based on neutron generation in a pitcher-catcher scenario, anisotropy in neutron emission was studied for the deuterium-deuterium fusion reaction. Simulation results are consistent with the narrow-divergence (∼ 70 ° full width at half maximum) neutron beam recently served in an experiment employing multi-MeV deuteron beams of narrow divergence (up to 30° FWHM, depending on the ion energy) accelerated by a sub-petawatt laser pulse from thin deuterated plastic foils via the Target Normal Sheath Acceleration mechanism. By varying the input ion beam parameters, simulations show that a further improvement in the neutron beam directionality (i.e. reduction in the beam divergence) can be obtained by increasing the projectile ion beam temperature and cut-off energy, as expected from interactions employing higher power lasers at upcoming facilities.

  17. Simulation Studies of Beam-Beam Effects of a Ring-Ring Electron-Ion Collider Based on CEBAF

    SciTech Connect

    Yuhong Zhang,Ji Qiang

    2009-05-01

    The collective beam-beam effect can potentially cause a rapid growth of beam sizes and reduce the luminosity of a collider to an unacceptably low level. The ELIC, a proposed ultra high luminosity electron-ion collider based on CEBAF, employs high repetition rate crab crossing colliding beams with very small bunch transverse sizes and very short bunch lengths, and collides them at up to 4 interaction points with strong final focusing. All of these features can make the beam-beam effect challenging. In this paper, we present simulation studies of the beam-beam effect in ELIC using a self-consistent strong-strong beam-beam simulation code developed at Lawrence Berkeley National Laboratory. This simulation study is used for validating the ELIC design and for searching for an optimal parameter set.

  18. ATOMIC BEAM STUDIES IN THE RHIC H-JET POLARIMETER.

    SciTech Connect

    MAKDISI,Y.; ZELENSKI,A.; GRAHAM,D.; KOKHANOVSKI,S.; MAHLER,G.; NASS,A.; RITTER,J.; ZUBETS,V.; ET AL.

    2005-01-28

    The results of atomic beam production studies are presented. Improved cooling of the atoms before jet formation in the dissociator cold nozzle apparently reduces the atomic beam velocity spread and improves beam focusing conditions. A carefully designed sextupole separating (and focusing) magnet system takes advantage of the high brightness source. As a result a record beam intensity of a 12.4 {center_dot} 10{sup 16} atoms/s was obtained within 10 mm acceptance at the collision point. The results of the polarization dilution factor measurements (by the hydrogen molecules at the collision point) are also presented.

  19. Experimental Studies of Ion Beam Neutralization: Preliminary Results

    SciTech Connect

    Ding, N.; Polansky, J.; Downey, R.; Wang, J.

    2011-05-20

    A testing platform is designed to study ion beam neutralization in the mesothermal, collisionless region. In the experimental setup, argon neutrals were ionized in a microwave cavity and accelerated by a plasma lens system which was biased to 2500 V above the system ground. Electrons were boiled off from two hot tungsten filaments to neutralize the ion beam. The plasma is diagnosed using Langmuir probe and Faraday probe. A 3-D traversing system and a complete data acquisition loop were developed to efficiently measure 3-D beam profile. Preliminary measurements of beam profiles are presented for different operating conditions.

  20. Topics on distance correlation, feature screening and lifetime expectancy with application to Beaver Dam eye study data

    NASA Astrophysics Data System (ADS)

    Kong, Jing

    This thesis includes 4 pieces of work. In Chapter 1, we present the work with a method for examining mortality as it is seen to run in families, and lifestyle factors that are also seen to run in families, in a subpopulation of the Beaver Dam Eye Study that has died by 2011. We find significant distance correlations between death ages, lifestyle factors, and family relationships. Considering only sib pairs compared to unrelated persons, distance correlation between siblings and mortality is, not surprisingly, stronger than that between more distantly related family members and mortality. Chapter 2 introduces a feature screening procedure with the use of distance correlation and covariance. We demonstrate a property for distance covariance, which is incorporated in a novel feature screening procedure based on distance correlation as a stopping criterion. The approach is further implemented to two real examples, namely the famous small round blue cell tumors data and the Cancer Genome Atlas ovarian cancer data Chapter 3 pays attention to the right censored human longevity data and the estimation of lifetime expectancy. We propose a general framework of backward multiple imputation for estimating the conditional lifetime expectancy function and the variance of the estimator in the right censoring setting and prove the properties of the estimator. In addition, we apply the method to the Beaver Dam eye study data to study human longevity, where the expected human lifetime are modeled with smoothing spline ANOVA based on the covariates including baseline age, gender, lifestyle factors and disease variables. Chapter 4 compares two imputation methods for right censored data, namely the famous Buckley-James estimator and the backward imputation method proposed in Chapter 3 and shows that backward imputation method is less biased and more robust with heterogeneity.

  1. Crossed molecular beam studies of atmospheric chemical reaction dynamics

    SciTech Connect

    Zhang, Jingsong

    1993-04-01

    The dynamics of several elementary chemical reactions that are important in atmospheric chemistry are investigated. The reactive scattering of ground state chlorine or bromine atoms with ozone molecules and ground state chlorine atoms with nitrogen dioxide molecules is studied using a crossed molecular beams apparatus with a rotatable mass spectrometer detector. The Cl + O{sub 3} {yields} ClO + O{sub 2} reaction has been studied at four collision energies ranging from 6 kcal/mole to 32 kcal/mole. The derived product center-of-mass angular and translational energy distributions show that the reaction has a direct reaction mechanism and that there is a strong repulsion on the exit channel. The ClO product is sideways and forward scattered with respect to the Cl atom, and the translational energy release is large. The Cl atom is most likely to attack the terminal oxygen atom of the ozone molecule. The Br + O{sub 3} {yields} ClO + O{sub 2} reaction has been studied at five collision energies ranging from 5 kcal/mole to 26 kcal/mole. The derived product center-of-mass angular and translational energy distributions are quite similar to those in the Cl + O{sub 3} reaction. The Br + O{sub 3} reaction has a direct reaction mechanism similar to that of the Cl + O{sub 3} reaction. The electronic structure of the ozone molecule seems to play the central role in determining the reaction mechanism in atomic radical reactions with the ozone molecule. The Cl + NO{sub 2} {yields} ClO + NO reaction has been studied at three collision energies ranging from 10.6 kcal/mole to 22.4 kcal/mole. The center-of-mass angular distribution has some forward-backward symmetry, and the product translational energy release is quite large. The reaction proceeds through a short-lived complex whose lifetime is less than one rotational period. The experimental results seem to show that the Cl atom mainly attacks the oxygen atom instead of the nitrogen atom of the NO{sub 2} molecule.

  2. Potential for Adult-Based Epidemiological Studies to Characterize Overall Cancer Risks Associated with a Lifetime of CT Scans

    PubMed Central

    Shuryak, Igor; Lubin, Jay H.; Brenner, David J.

    2014-01-01

    Recent epidemiological studies have suggested that radiation exposure from pediatric CT scanning is associated with small excess cancer risks. However, the majority of CT scans are performed on adults, and most radiation-induced cancers appear during middle or old age, in the same age range as background cancers. Consequently, a logical next step is to investigate the effects of CT scanning in adulthood on lifetime cancer risks by conducting adult-based, appropriately designed epidemiological studies. Here we estimate the sample size required for such studies to detect CT-associated risks. This was achieved by incorporating different age-, sex-, time- and cancer type-dependent models of radiation carcinogenesis into an in silico simulation of a population-based cohort study. This approach simulated individual histories of chest and abdominal CT exposures, deaths and cancer diagnoses. The resultant sample sizes suggest that epidemiological studies of realistically sized cohorts can detect excess lifetime cancer risks from adult CT exposures. For example, retrospective analysis of CT exposure and cancer incidence data from a population-based cohort of 0.4 to 1.3 million (depending on the carcinogenic model) CT-exposed UK adults, aged 25–65 in 1980 and followed until 2015, provides 80% power for detecting cancer risks from chest and abdominal CT scans. PMID:24828111

  3. Experimental study of the longitudinal instability for beam transport

    SciTech Connect

    Reiser, M.; Wang, J.G.; Guo, W.M.; Wang, D.X.

    1990-01-01

    Theoretical model for beam longitudinal instability in a transport pipe with general wall impedance is considered. The result shows that a capacitive wall tends to stabilize the beam. The experimental study of the instability for a pure resistive-wall is presented, including the design parameters, setup and components for the experiment. 6 refs., 3 figs.

  4. Association between Lifetime Physical Activity and Cognitive Functioning in Middle-Aged and Older Community Dwelling Adults: Results from the Brain in Motion Study.

    PubMed

    Gill, Stephanie J; Friedenreich, Christine M; Sajobi, Tolulope T; Longman, R Stewart; Drogos, Lauren L; Davenport, Margie H; Tyndall, Amanda V; Eskes, Gail A; Hogan, David B; Hill, Michael D; Parboosingh, Jillian S; Wilson, Ben J; Poulin, Marc J

    2015-11-01

    To determine if total lifetime physical activity (PA) is associated with better cognitive functioning with aging and if cerebrovascular function mediates this association. A sample of 226 (52.2% female) community dwelling middle-aged and older adults (66.5 ± 6.4 years) in the Brain in Motion Study, completed the Lifetime Total Physical Activity Questionnaire and underwent neuropsychological and cerebrovascular blood flow testing. Multiple robust linear regressions were used to model the associations between lifetime PA and global cognition after adjusting for age, sex, North American Adult Reading Test results (i.e., an estimate of premorbid intellectual ability), maximal aerobic capacity, body mass index and interactions between age, sex, and lifetime PA. Mediation analysis assessed the effect of cerebrovascular measures on the association between lifetime PA and global cognition. Post hoc analyses assessed past year PA and current fitness levels relation to global cognition and cerebrovascular measures. Better global cognitive performance was associated with higher lifetime PA (p=.045), recreational PA (p=.021), and vigorous intensity PA (p=.004), PA between the ages of 0 and 20 years (p=.036), and between the ages of 21 and 35 years (p.5), but partially mediated the relation between current fitness and global cognition. This study revealed significant associations between higher levels of PA (i.e., total lifetime, recreational, vigorous PA, and past year) and better cognitive function in later life. Current fitness levels relation to cognitive function may be partially mediated through current cerebrovascular function. PMID:26581793

  5. Ab initio study of permanent electric dipole moment and radiative lifetimes of alkaline-earth-metal--Li molecules

    SciTech Connect

    Gopakumar, Geetha; Abe, Minori; Hada, Masahiko; Kajita, Masatoshi

    2011-12-15

    We calculate permanent electric dipole moments (PDMs), as well as spontaneous and black body lifetimes, of alkaline-earth-metal-Li (AEM-Li) ultracold polar molecules to study anisotropic long-range dipole-dipole interactions in a single quantum state. We obtain potential energy curves for the {sup 2} {Sigma} ground state of MgLi, CaLi, SrLi, and BaLi molecules at the coupled cluster singles and doubles with partial triples [CCSD(T)] level of electron correlation. Calculated spectroscopic constants for the isotopes: {sup 24}Mg{sup 7}Li, {sup 40}Ca{sup 7}Li, {sup 88}Sr{sup 7}Li, and {sup 138}Ba{sup 7}Li, show good agreement with available theoretical and experimental results. We obtain PDM curves using finite field perturbation theory at the CCSD(T) level. We find that AEM-Li molecules have moderate values of PDM at the equilibrium bond distance (MgLi: 0.90 D, CaLi: 1.15 D, SrLi: 0.33 D, and BaLi: -0.42 D) and hence might be suitable candidates for the proposed study in a single quantum state. Radiative lifetime calculations of the {nu} = 0 state ({sup 24}Mg{sup 6}Li: 22 s, {sup 40}Ca{sup 6}Li: 39 s, {sup 88}Sr{sup 6}Li: 380 s, and {sup 138}Ba{sup 6}Li: 988 s) are found to be longer than the typical time scale associated with ultracold experiments with these molecules. The uncertainty in the lifetime calculations are estimated to be less than 10%.

  6. Lifetime toxicity/carcinogenicity study of FD & C Red No. 40 (allura red) in Sprague-Dawley rats.

    PubMed

    Borzelleca, J F; Olson, J W; Reno, F E

    1989-11-01

    FD & C Red No. 40 was fed to Charles River CD (Sprague-Dawley) rats as a dietary admixture in a lifetime toxicity/carcinogenicity study. The study included a phase during which the colouring was administered to parental rats (30 of each sex per group) at concentrations of 0.0, 0.37, 1.39 and 5.19%, throughout the mating, gestation and lactation periods. The concurrent control group received the basal diet. After random selection of the first-generation rats, the lifetime phase was initiated using the same dietary concentrations with 50 rats of each sex per group. The maximum durations of exposure to the colouring were 118 and 121 for males and females, respectively. No compound-related adverse effects were observed, except for a reduction in body weight in high-dose females at the end of the study. The no-adverse-effect levels in this study were 5.19% (2829 mg/kg/day) for male rats, and 1.39% (901 mg/kg/day) for female rats.

  7. Lifetime studies of Mo/Si and Mo/Be multilayer coatings for extreme ultraviolet lithography

    SciTech Connect

    Bajt, S; Clift, W M; Folta, J A; Gullikson, E M; Klebanoff, L E; Kleineberg, U; Malinowski, M E; Wedowski, M

    1999-08-05

    Extreme Ultraviolet Lithography (EUVL) is a candidate for future application by the semiconductor industry in the production of sub-100 nm feature sizes in integrated circuits. Using multilayer reflective coatings optimized at wavelengths ranging from 11 to 14 nm, EUVL represents a potential successor to currently existing optical lithography techniques. In order to assess lifetimes of the multilayer coatings under realistic conditions, a series of radiation stability tests has been performed. In each run a dose of EUV radiation equivalent to several months of lithographic operation was applied to Mo/Si and MO/Be multilayer coatings within a few days. Depending on the residual gas concentration in the vacuum environment, surface deposition of carbon during the exposure lead to losses in the multilayer reflectivity. However, in none of the experimental runs was structural damage within the bulk of the multilayers observed. Mo/Si multilayer coatings recovered their full original reflectivity after removal of the carbon layer by an ozone cleaning method. Auger depth profiling on MO/Be multilayers indicate that carbon penetrated into the Be top layer during illumination with high doses of EUV radiation. Subsequent ozone cleaning fully removed the carbon, but revealed enhanced oxidation of the area illuminated, which led to an irreversible loss in reflectance on the order of 1%. Keywords: Extreme ultraviolet (EUV) lithography, multilayer reflective coatings, radiation stability, surface contamination

  8. CdSeS/ZnS alloyed nanocrystal lifetime and blinking studies under electrochemical control.

    PubMed

    Qin, Wei; Shah, Raman A; Guyot-Sionnest, Philippe

    2012-01-24

    Alloyed CdSeS nanocrystals allow tuning between the CdSe and CdS band edges while remaining relatively small. The CdSeS cores also lead to a reduced electron confinement energy and a slower biexciton decay rate compared to CdSe cores of similar sizes. A ZnS shell synthesis procedure allows stable CdSeS/ZnS colloidal quantum dots (QDs) suitable for single dot imaging. These are compared to CdSe/ZnS of similar core size. The blinking off-exponents of the CdSeS/ZnS dots in air and on a glass substrate were slightly larger. Using electrochemistry with ensemble and single dot measurements, the trion lifetime of CdSeS/ZnS dot is resolved to be ~0.75 ns, while it is about 0.15 ns for CdSe/ZnS. In addition, the blinking behavior of single CdSeS/ZnS QDs is largely suppressed when in the trion state.

  9. Residual on column host cell protein analysis during lifetime studies of protein A chromatography.

    PubMed

    Lintern, Katherine; Pathak, Mili; Smales, C Mark; Howland, Kevin; Rathore, Anurag; Bracewell, Daniel G

    2016-08-26

    Capacity reduction in protein A affinity chromatography with extended cycling during therapeutic antibody manufacture is well documented. Identification of which residual proteins remain from previous cycles during the lifetime of these adsorbent materials is required to understand their role in this ageing process, but represents a significant metrological challenge. Scanning electron microscopy (SEM) and liquid chromatography mass spectrometry (LC-MS/MS) are combined to detect and map this phenomenon of protein carry-over. We show that there is a morphological change at the surface of the agarose resin, revealing deposits on the polymer fibres increasing with cycle number. The amount of residual host cell proteins (HCPs) by LC-MS/MS present on the resin is shown to increase 10-fold between 50 and 100 cycles. During this same period the functional class of the predominant HCPs associated with the resin increased in diversity, with number of proteins identified increasing 5-fold. This ageing is observed in the context of the product quality of the eluate HCP and protein A leachate concentration remaining constant with cycle number. PMID:27473513

  10. SUMMARY OF BEAM BEAM OBSERVATIONS DURING STORES IN RHIC.

    SciTech Connect

    FISCHER,W.

    2003-05-19

    During stores, the beam-beam interaction has a significant impact on the beam and luminosity lifetimes in RHIC. This was observed in heavy ion, and even more pronounced in proton collisions. Observations include measurements of beam-beam induced tune shifts, lifetime and emittance growth measurements with and without beam-beam interaction, and background rates as a function of tunes. In addition, RHIC is currently the only hadron collider in which strong-strong beam-beam effects can be seen. Coherent beam-beam modes were observed, and suppressed by tune changes. In this article we summarize the most important beam-beam observations made during stores so far.

  11. Radioactive beam studies of cosmological interest

    NASA Astrophysics Data System (ADS)

    Sale, K. E.; Boyd, R. N.; Mathews, G. J.; Corn, P. B.; Islam, M. S.

    1989-04-01

    Experimental efforts by the LLNL/Ohio State radioactive ion beam collaboration are described. We are presently focusing on some reactions which are of great importance in the newly proposed inhomogeneous big bang cosmological models [G.M. Fuller, G.J. Mathews and C.R. Alcock, in: Origin and Distribution of the Elements, ed. G.J. Mathews (World Scientific, Singapore, 1987)]. Specifically we are using our system to make beams of 8Li for measurements of the 8Li(d, n)9Be and 8Li(a, n)11B cross sections. These are the key reactions which determine the production of heavy (A > 12) elements during the era of big bang nucleosynthesis, and thus the initial composition of stars and subsequent stellar isotope production. Plans for future experiments, including the measurement of the 7Be(p, γ)8B cross section will be discussed.

  12. Neutral beam source commercialization study. Final report

    SciTech Connect

    King, H.J.

    1980-06-01

    The basic tasks of this Phase II project were to: generate a set of design drawings suitable for quantity production of sources of this design; fabricate a functional neutral beam source incorporating as many of the proposed design changes as proved feasible; and document the procedures and findings developed during the contract. These tasks have been accomplished and represent a demonstrated milestone in the industrialization of this complete device.

  13. Lifetime exposure to traumatic psychological stress is associated with elevated inflammation in the heart and soul study

    PubMed Central

    O’Donovan, Aoife; Neylan, Thomas C.; Metzler, Thomas; Cohen, Beth E.

    2012-01-01

    Exposure to traumatic psychological stress increases risk for disease events and mortality in patients with cardiovascular disease (CVD). While the biological mechanisms of these effects are not known, inflammation may play a key role as it is both elevated by psychological stress and involved in the development and progression of CVD. In a prospective study of patients with stable CVD (n = 979), we examined if higher lifetime trauma exposure was associated with elevated levels of inflammation at baseline and at five-year follow-up, and with greater increases in inflammation over time. Inflammation was indexed by a composite score incorporating the inflammatory markers interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP) and resistin. In follow-up analyses, we adjusted for sociodemographic factors, psychiatric disorders and health behaviors that were significantly associated with trauma exposure. Higher trauma exposure was associated with elevated inflammation at baseline (β = .09, p = .01) and at five-year follow-up (β = .09, p = .03). While levels of inflammation increased from baseline to follow-up in the sample, there was no significant association between trauma exposure and rate of change in inflammation. Findings were robust to adjustments for sociodemographic factors and psychiatric disorders, but health behaviors appeared to contribute to the association between trauma and inflammation at follow-up. This is the first large-scale demonstration of an association between lifetime trauma exposure and inflammation. High lifetime exposure to traumatic stress may contribute to an accelerated rate of CVD progression through elevated inflammation. PMID:22366689

  14. Beam Loss Studies for Rare Isotope Driver Linacs Final Report

    SciTech Connect

    Wangler, T P; Kurennoy, S S; Billen, J H; Crandall, K R; Qiang, J; Ryne, R D; Mustapha, B; Ostroumov, P; Zhao, Q; York, and R. C.

    2008-03-26

    The Fortran 90 RIAPMTQ/IMPACT code package is a pair of linked beam-dynamics simulation codes that have been developed for end-to-end computer simulations of multiple-charge-state heavy-ion linacs for future exotic-beam facilities. These codes have multiple charge-state capability, and include space-charge forces. The simulations can extend from the low-energy beam-transport line after an ECR ion source to the end of the linac. The work has been performed by a collaboration including LANL, LBNL, ANL, and MSU. The code RIAPMTQ simulates the linac front-end beam dynamics including the LEBT, RFQ, and MEBT. The code IMPACT simulates the beam dynamics of the main superconducting linac. The codes have been benchmarked for rms beam properties against previously existing codes at ANL and MSU. The codes allow high-statistics runs on parallel supercomputing platforms, particularly at NERSC at LBNL, for studies of beam losses. The codes also run on desktop PC computers for low-statistics work. The code package is described in more detail in a recent publication [1] in the Proceedings of PAC07 (2007 US Particle Accelerator Conference). In this report we describe the main activities for the FY07 beam-loss studies project using this code package.

  15. Long-Range And Head-On Beam-Beam Compensation Studies in RHIC With Lessons for the LHC

    SciTech Connect

    Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; Dorda, U.; Koutchouk, J.P.; Sterbini, G.; Zimmermann, F.; Kim, H.J.; Sen, T.; Shiltsev, V.; Valishev, A.; Qiang, J.; Kabel, A.; /SLAC

    2011-11-28

    Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

  16. Long-range and head-on beam-beam compensation studies in RHIC with lessons for the LHC

    SciTech Connect

    Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; Dorda, U.; Koutchouk, J.-P.; Sterbini, G.; Zimmermann, F.; Kim, H.-J.; Sen, T.; Shiltsev, V.; Valishev, A.; Qiang, J.; Kabel, A.

    2009-01-12

    Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are also important consideration for the LHC upgrades. To mitigate long-range effects, current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. Electron lenses were proposed for both RHIC and the LHC to reduce the head-on beam-beam effect. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

  17. Long-range and head-on beam-beam compensation studies in RHIC with lessons for the LHC

    SciTech Connect

    Fischer,W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G.; Dorda, U.; Koutchouk, J. -P.; Sterbini, G.; Zimmermann, F.; Kim, H. -J.; Sen, T.; Shiltsev, V.; Valishev, A.; Qiang, J.; Kabel, A.

    2008-11-24

    Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are also important consideration for the LHC upgrades. To mitigate long-range effects current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. To reduce the head-on beam-beam effect electron lenses were proposed for both RIDC and the LHC. We present the experimental long-range beam-beam program at RHIC and report on head-on compensations studies based on simulations.

  18. The Fraction of the Sun's Lifetime in a Grand Minimum State Estimated from Studies of Solar-Type Stars

    NASA Astrophysics Data System (ADS)

    Lubin, D.

    2011-12-01

    The Maunder Minimum is a key event in climate change research, (1) from the vantage point as a natural control experiment in which greenhouse gas (GHG) abundances were at a pre-industrial constant while solar forcing changed by a magnitude comparable to recent GHG increases, and (2) given recent interest and speculation that a similar grand minimum might occur later this century. To date, periodicity in solar grand minima has been difficult to detect in geophysical proxy data, and an alternative approach involves estimating the frequency of the Sun's lifetime spent in a grand minimum state by searching for evidence of grand minima in solar-type stars. Most often this is done by measuring Ca H and K flux as an indicator of chromospheric activity, or by photometric observations of solar cycles on decadal timescales. Early estimates of grand minimum frequency in solar type stars ranged from 10-30%. However, these early studies inadvertently included many stars that have evolved off the main sequence. This paper discusses how measurements of stellar Lithium abundance, and spectroscopically constrained metallicity, are used as additional constraints on age and main sequence membership, to refine detections of grand minima in solar-type stars. Based on the most recent studies, an estimate emerges of 5-6% for the fraction of the Sun's lifetime spent in a low-activity and reduced luminosity state analogous to the Maunder Minimum.

  19. A positron annihilation lifetime spectroscopic study of the corrosion protective properties of epoxy coatings

    SciTech Connect

    MacQueen, R.C.

    1992-01-01

    Positron Annihilation Lifetime Spectroscopy (PALS) was used to measure the free volume cavity sizes and free volume fractions of crosslinked epoxy coatings on steel before and after saturation with liquid water at 23[degrees]C. A direct linear relationship between the equilibrium volume fraction of water absorbed and the dry relative free volume fraction of bisphenol A epoxy coatings was found. The free volume cavity sizes and the number of free volume cavities per unit volume of these epoxies were found to decrease after water saturation. These decreases are ascribed to the occupation of 13-17% of the free volume cavities by 2-4 water molecules per cavity. The free volume cavity size of polyglycol diepoxides was found to increase after water saturation. This increase is ascribed to the expansion of the free volume cavities by water, which is substantiated by the macroscopic swelling observed in these coatings. An inverse, linear relationship between the equilibrium water uptake and the relative free volume fraction of these coatings were observed. This result coupled with the fact that less than one molecule of nitrobenzene was determined to fit into an epoxy free volume cavity, and that nitrobenzene is quite soluble in most of the epoxides, indicates that other factors besides the magnitude of the free volume fraction affect the amount of solvent absorbed by epoxy coatings. The small percentage of free volume occupied by water and the small number of water molecules capable of filling each void of the bisphenol A epoxies after water saturation correlate to the high impedance values and the good corrosion protection of these coatings, suggesting that water passes through these coatings by slow diffusion through the connected free volume cavities in the coating. Increases in the free volume cavity sizes of the polyglycol diepoxides after water saturation correlate to the low impedance and the poor corrosion protection of these coatings.

  20. Macroparticle simulation studies of a proton beam haloexperiment

    SciTech Connect

    Qiang, J.; Colestock, P.L.; Gilpatrick, D.; Smith, H.V.; Wangler,T.P.; Schulze, M.E.

    2002-09-12

    We report macroparticle simulations for comparison withmeasured results from a proton beam-halo experiment in a 52-quadrupoleperiodic-focusing channel. An important issue is that the inputphase-space distribution is not experimentally known. Three differentinitial distributions with different shapes predict different beamprofiles in the transport system. Simulations have been fairly successfulin reproducing the core of the measured matched-beam profiles and thetrend of emittance growth as a function of mismatch factor, butunderestimate the growth rate of halo and emittance for mismatched beams.In this study, we find that knowledge of the Courant-Snyder parametersand emittances of the input beam is not sufficient for reliableprediction of the halo. Input distributions iwth greater population inthe tails produce larger rates of emittance growth, a result that isqualitatively consistent with the particle-core model of halo formationin mismatched beams.

  1. Lifetime measurements in 180Pt

    NASA Astrophysics Data System (ADS)

    Chen, Q. M.; Wu, X. G.; Chen, Y. S.; Li, C. B.; Gao, Z. C.; Li, G. S.; Chen, F. Q.; He, C. Y.; Zheng, Y.; Hu, S. P.; Zhong, J.; Wu, Y. H.; Li, H. W.; Luo, P. W.

    2016-04-01

    Lifetimes of the yrast states in 180Pt have been measured from 4+ to 8+ using the recoil distance Doppler-shift technique in the coincidence mode. These states were populated by the reaction 156Gd(28Si,4 n )180Pt at a beam energy of 144 MeV. The differential decay curve method was applied to determine the lifetimes from experimental coincidence data. The B (E 2 ) values extracted from lifetimes increase with increasing spin, implying rotor behavior, but do not show the typical shape coexistence where the B (E 2 ) values present a rapid increase at very low spins. Calculations based on the triaxial projected shell model were performed for the yrast states in 180Pt and the results of both energies and E 2 transition probabilities reproduce the experimental data very well. The result also shows that a better description of the yrast band in 180Pt requires consideration of the γ degree of freedom.

  2. Polarization Studies in Fast-Ion Beam Spectroscopy

    SciTech Connect

    Trabert, E

    2001-12-20

    In a historical review, the observations and the insight gained from polarization studies of fast ions interacting with solid targets are presented. These began with J. Macek's recognition of zero-field quantum beats in beam-foil spectroscopy as indicating alignment, and D.G. Ellis' density operator analysis that suggested the observability of orientation when using tilted foils. Lastly H. Winter's studies of the ion-beam surface interaction at grazing incidence yielded the means to produce a high degree of nuclear orientation in ion beams.

  3. Cellular track model for study of heavy ion beams

    NASA Technical Reports Server (NTRS)

    Shinn, Judy L.; Katz, Robert; Cucinotta, Francis A.; Wilson, John W.; Ngo, Duc M.

    1993-01-01

    Track theory is combined with a realistic model of a heavy ion beam to study the effects of nuclear fragmentation on cell survival and biological effectiveness. The effects of secondary reaction products are studied as a function of depth in a water column. Good agreement is found with experimental results for the survival of human T-l cells exposed to monoenergetic carbon, neon, and argon beams under aerobic and hypoxia conditions. The present calculation, which includes the effect of target fragmentation, is a significant improvement over an earlier calculation because of the use of a vastly improved beam model with no change in the track theory or cellular response parameters.

  4. Lifetime Prevalence of Suicide Attempts Among Sexual Minority Adults by Study Sampling Strategies: A Systematic Review and Meta-Analysis

    PubMed Central

    Bogaert, Laura; Rhodes, Anne E.; Brennan, David J.; Gesink, Dionne

    2016-01-01

    Background. Previous reviews have demonstrated a higher risk of suicide attempts for lesbian, gay, and bisexual (LGB) persons (sexual minorities), compared with heterosexual groups, but these were restricted to general population studies, thereby excluding individuals sampled through LGB community venues. Each sampling strategy, however, has particular methodological strengths and limitations. For instance, general population probability studies have defined sampling frames but are prone to information bias associated with underreporting of LGB identities. By contrast, LGB community surveys may support disclosure of sexuality but overrepresent individuals with strong LGB community attachment. Objectives. To reassess the burden of suicide-related behavior among LGB adults, directly comparing estimates derived from population- versus LGB community–based samples. Search methods. In 2014, we searched MEDLINE, EMBASE, PsycInfo, CINAHL, and Scopus databases for articles addressing suicide-related behavior (ideation, attempts) among sexual minorities. Selection criteria. We selected quantitative studies of sexual minority adults conducted in nonclinical settings in the United States, Canada, Europe, Australia, and New Zealand. Data collection and analysis. Random effects meta-analysis and meta-regression assessed for a difference in prevalence of suicide-related behavior by sample type, adjusted for study or sample-level variables, including context (year, country), methods (medium, response rate), and subgroup characteristics (age, gender, sexual minority construct). We examined residual heterogeneity by using τ2. Main results. We pooled 30 cross-sectional studies, including 21 201 sexual minority adults, generating the following lifetime prevalence estimates of suicide attempts: 4% (95% confidence interval [CI] = 3%, 5%) for heterosexual respondents to population surveys, 11% (95% CI = 8%, 15%) for LGB respondents to population surveys, and 20% (95% CI

  5. Radiation hardness and lifetime studies of LEDs and VCSELs for the optical readout of the ATLAS SCT

    NASA Astrophysics Data System (ADS)

    Beringer, J.; Borer, K.; Mommsen, R. K.; Nickerson, R. B.; Weidberg, A. R.; Monnier, E.; Hou, H. Q.; Lear, K. L.

    1999-10-01

    We study the radiation hardness and the lifetime of Light Emitting Diodes (LEDs) and Vertical Cavity Surface Emitting Laser diodes (VCSELs) in the context of the development of the optical readout for the ATLAS SemiConductor Tracker (SCT) at LHC. About 170 LEDs from two different manufacturers and about 130 VCSELs were irradiated with neutron and proton fluences equivalent to (and in some cases more than twice as high as) the combined neutral and charged particle fluence of about 5×10 14 n (1 MeV eq. in GaAs)/cm 2 expected in the ATLAS inner detector. We report on the radiation damage and the conditions required for its partial annealing under forward bias, we calculate radiation damage constants, and we present post-irradiation failure rates for LEDs and VCSELs. The lifetime after irradiation was investigated by operating the diodes at an elevated temperature of 50°C for several months, resulting in operating times corresponding to up to 70 years of operation in the ATLAS SCT. From our results we estimate the signal-to-noise ratio and the failure rate of optical links using LEDs developed specifically for application at LHC.

  6. The free volume in dried and H2O-loaded biopolymers studied by positron lifetime measurements.

    PubMed

    Hugenschmidt, Christoph; Ceeh, Hubert

    2014-08-01

    We present experiments on glucose-gelatin compounds using positron annihilation lifetime spectroscopy (PALS) in order to study the behavior of the free volume dependent on H2O loading, drying, and uniaxial pressure. A semiempirical quantum mechanical model was applied in order to correlate the lifetime of orthopositronium in nanoscaled voids to the void size. This allowed us to determine the absolute value of the mean void radius in the biopolymer samples. In addition, the variation of the total free volume of the differently treated samples is quantified and illustrated by a log-normal distribution function. Most interesting results have been obtained after saturation loading with H2O that leads to the formation of voids with a mean size of 84.3(1.9) Å(3) and to an increase of the total free volume by a factor of 2.5. This observation in the swelled sample is explained by the entropy elastic regime well above the glass transition temperature that greatly facilitates the formation of free volume. Differential scanning calorimetry (DSC) measurements were performed in order to determine the glass transition temperature and to support the interpretation of the results obtained by PALS. PMID:25046083

  7. Angiotensin II-induced angiotensin II type I receptor lysosomal degradation studied by fluorescence lifetime imaging microscopy

    NASA Astrophysics Data System (ADS)

    Li, Hewang; Yu, Peiying; Felder, Robin A.; Periasamy, Ammasi; Jose, Pedro A.

    2009-02-01

    Upon activation, the angiotensin (Ang) II type 1 receptor (AT1Rs) rapidly undergoes endocytosis. After a series of intracellular processes, the internalized AT1Rs recycle back to the plasma membrane or are trafficked to proteasomes or lysosomes for degradation. We recently reported that AT1Rs degrades in proteasomes upon stimulation of the D5 dopamine receptor (D5R) in human renal proximal tubule and HEK-293 cells. This is in contrast to the degradation of AT1R in lysosomes upon binding Ang II. However, the dynamic regulation of the AT1Rs in lysosomes is not well understood. Here we investigated the AT1Rs lysosomal degradation using FRET-FLIM in HEK 293 cells heterologously expressing the human AT1R tagged with EGFP as the donor fluorophore. Compared to its basal state, the lifetime of AT1Rs decreased after a 5-minute treatment with Ang II treatment and colocalized with Rab5 but not Rab7 and LAMP1. With longer Ang II treatment (30 min), the AT1Rs lifetime decreased and co-localized with Rab5, as well as Rab7 and LAMP1. The FLIM data are corroborated with morphological and biochemical co-immunoprecipitation studies. These data demonstrate that Ang II induces the internalization of AT1Rs into early sorting endosomes prior to trafficking to late endosomes and subsequent degradation in lysosomes.

  8. Multi-wavelength fluorescence lifetime spectroscopy: a new approach to the study of endogenous fluorescence in living cells and tissues

    NASA Astrophysics Data System (ADS)

    Chorvat, D., Jr.; Chorvatova, A.

    2009-03-01

    The study of biological systems in their real environmental conditions is crucial to decipher the true image of structures and processes underlying their functionality. In this regard, development of non-invasive optical techniques that do not require labelling, such as the investigation of tissue endogenous fluorescence, is particularly important and, as reflected in the increasing number of contributions published recently on this subject, was recognized by many leading groups. Multi-spectral and lifetime detection of fluorescence provides an effective experimental tool to discriminate between multiple naturally-occurring fluorophores in living tissues. At the same time, however, data analysis allowing us to understand the spectral, temporal and spatial information gathered, describing individual molecules involved in the autofluorescence of intact biological systems, represents a tough scientific challenge that has not yet been fully resolved. In this review, we discuss the latest advances in technologies that record and assess spectrally-resolved fluorescence lifetime data as well as their biological and clinical applications. We show how these methods provide efficient sensing of molecules correlated with changes in the mitochondrial metabolic redox state in pathological conditions and/or of cell ultrastructures in diseased tissue, based on the presence of oxidation/reduction-sensitive fluorophores and/or cell-specific chromophores. Future directions are also outlined.

  9. Precision neutron flux measurement with a neutron beam monitor

    NASA Astrophysics Data System (ADS)

    Ino, T.; Otono, H.; Mishima, K.; Yamada, T.

    2014-07-01

    Neutron beam monitors are regularly used in various neutron beam experiments to compare two or more sets of data taken in different experimental conditions. A neutron lifetime experiment at BL05, the NOP beamline, in J-PARC requires to monitor the initial neutron intensity with an precision of 0.1% to measure the neutron lifetime with the same accuracy. The performance of a thin 3He gas neutron beam monitor used for the experiment was studied to estimate the systematic uncertainties in the neutron lifetime measurement.

  10. Spes: Exotic Beams for Nuclear Physics Studies

    NASA Astrophysics Data System (ADS)

    Andrighetto, Alberto; Manzolaro, Mattia; Corradetti, Stefano; Scarpa, Daniele; Vasquez, Jesu; Rossignoli, Massimo; Monetti, Alberto; Calderolla, Michele; Prete, Gianfranco

    2014-02-01

    The SPES project at Laboratori di Legnaro of INFN (Italy) is concentrating on the production of neutron-rich radioactive nuclei for nuclear physics experiments using uranium fission at a rate of 1013 fission/s. The emphasis on neutron-rich isotopes is justified by the fact that this vast territory has been little explored. The Radioactive Ion Beam (RIB) will be produced by the ISOL technique using proton induced fission on a direct target of UCx. The most critical element of the SPES project is the Multi-Foil Direct Target. Up to the present time, the proposed target represents an innovation in terms of its capability to sustain the primary beam power. This talk will present the status of the project financed by INFN, which is actually in the construction phase at Legnaro. In particular, developments related to the target and the ion-source activities using the surface ion source, plasma ion source, and laser ion source techniques will be reported.

  11. Beam-beam compensation in Tevatron: Status report

    SciTech Connect

    Vladimir D. Shiltsev et al.

    2001-07-12

    The project of beam-beam compensation (BBC) in the Tevatron using electron beams [1] has passed a successful first step in experimental studies. The first Tevatron electron lens (TEL) has been installed in the Tevatron, commissioned, and demonstrated the theoretically predicted shift of betatron frequencies of a high energy proton beam due to a high current low energy electron beam. After the first series of studies in March-April 2001 (total of 7 shifts), we achieved tuneshifts of 980 GeV protons of about dQ=+0.007 with some 3 A of the electron beam current while the proton lifetime was in the range of 10 hours (some 24 hours at the best). Future work will include diagnostics improvement, beam studies with antiprotons, and fabrication of the 2nd TEL.

  12. Molecular beam facility for studying mass spectrometer performance

    NASA Technical Reports Server (NTRS)

    Ballenthin, J. O.; Nier, A. O.

    1981-01-01

    An apparatus which produces neutral gas beams in the velocity range from thermal to 6 km/s makes possible studies simulating the motion of instruments through tenuous atmospheres. Use of the apparatus in studying the response of an open-source mass spectrometer is examined. Experiments performed include responses when the instrument is in a normal mode of operation, when the ion source potentials are adjusted to reject striking gas particles, when the beam is restricted so that portions of the ion source are struck, and when the beam strikes at angles other than normal incidence. Results indicate specular radiation of particles out of the source and stagnation ratios close to unity for normal operation. Retarding potential studies dropped the sensitivity by a factor of about 10, and as angles of attack are varied, the effect was found to depend upon beam velocity and the way the ions are initially accelerated.

  13. Confined water in controlled pore glass CPG-10-120 studied by positron annihilation lifetime spectroscopy and differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    Šauša, O.; Mat'ko, I.; Illeková, E.; Macová, E.; Berek, D.

    2015-06-01

    The solidification and melting of water confined in the controlled pore glass (CPG) with average pore size 12.6 nm has been studied by differential scanning calorimetry (DSC) and positron annihilation lifetime spectroscopy (PALS). The fully-filled sample of CPG by water as well as the samples of CPG with different content of water were used. The measurements show the presence of amorphous and crystalline phases of water in this type and size of pores, freezing point depression of a confined liquid and presence of certain transitions at lower temperatures, which could be detected only for cooling regime. The localization of confined water in the partially filled pores of CPG at room temperature was studied.

  14. Ionosphere/microwave beam interaction study

    NASA Technical Reports Server (NTRS)

    Gordon, W. E.; Duncan, L. M.

    1978-01-01

    The microwave beam of the Solar Power Satellite (SPS) is predicted to interact with the ionosphere producing thermal runaway up to an altitude of about 100 kilometers at a power density threshold of 12 mW/cm sq (within a factor of two). The operation of the SPS at two frequencies, 2450 and 5800 MHz, is compared. The ionosphere interaction is less at the higher frequency, but the tropospheric problem scattering from heavy rain and hail is worse at the higher frequency. Microwave signals from communication satellites were observed to scintillate, but there is some concern that the uplink pilot signal may be distorted by the SPS heated ionosphere. The microwave scintillations are only observed in the tropics in the early evenings near the equinoxes. Results indicate that large phase errors in the uplink pilot signal can be reduced.

  15. Molecular Variation at the SLC6A3 Locus Predicts Lifetime Risk of PTSD in the Detroit Neighborhood Health Study

    PubMed Central

    Chang, Shun-Chiao; Koenen, Karestan C.; Galea, Sandro; Aiello, Allison E.; Soliven, Richelo; Wildman, Derek E.; Uddin, Monica

    2012-01-01

    Recent work suggests that the 9-repeat (9R) allele located in the 3′UTR VNTR of the SLC6A3 gene increases risk of posttraumatic stress disorder (PTSD). However, no study reporting this association to date has been based on population-based samples. Furthermore, no study of which we are aware has assessed the joint action of genetic and DNA methylation variation at SLC6A3 on risk of PTSD. In this study, we assessed whether molecular variation at SLC6A3 locus influences risk of PTSD. Participants (n = 320; 62 cases/258 controls) were drawn from an urban, community-based sample of predominantly African American Detroit adult residents, and included those who had completed a baseline telephone survey, had provided blood specimens, and had a homozygous genotype for either the 9R or 10R allele or a heterozygous 9R/10R genotype. The influence of DNA methylation variation in the SLC6A3 promoter locus was also assessed in a subset of participants with available methylation data (n = 83; 16 cases/67 controls). In the full analytic sample, 9R allele carriers had almost double the risk of lifetime PTSD compared to 10R/10R genotype carriers (OR = 1.98, 95% CI = 1.02–3.86), controlling for age, sex, race, socioeconomic status, number of traumas, smoking, and lifetime depression. In the subsample of participants with available methylation data, a significant (p = 0.008) interaction was observed whereby 9R allele carriers showed an increased risk of lifetime PTSD only in conjunction with high methylation in the SLC6A3 promoter locus, controlling for the same covariates. Our results confirm previous reports supporting a role for the 9R allele in increasing susceptibility to PTSD. They further extend these findings by providing preliminary evidence that a “double hit” model, including both a putatively reduced-function allele and high methylation in the promoter region, may more accurately capture molecular risk of PTSD at the SLC6A3 locus. PMID:22745713

  16. An analytical study on the bending of prismatic SMA beams

    NASA Astrophysics Data System (ADS)

    Ostadrahimi, Alireza; Arghavani, Jamal; Poorasadion, Saeid

    2015-12-01

    In this study, an analytical solution is presented for pure bending of shape memory alloy (SMA) beams with symmetric cross section as well as symmetric behavior in tension and compression. To this end, a three-dimensional constitutive equation is reduced to one-dimensional form and employed to study the bending response of SMA beams at high (pseudo-elasticity) and low (shape memory effect) temperatures. An analytical expression for bending stress as well as polynomial approximation for shear stress and deflection are obtained. Derived equations for bending are employed to analyze an SMA beam with rectangular cross section and results are compared with those of the finite element method. The results of this work show good agreement when compared with experimental data and finite element results. Furthermore, the existence of several zero-stress fibers during unloading of SMA beams at low temperature is demonstrated.

  17. Glucose and water diffusion kinetics study in a fluorosilicone acrylate contact lens material by positron lifetime spectroscopy.

    PubMed

    Deepa Urs, M V; Ranganathaiah, C

    2007-01-01

    A comparative study of water and glucose sorption in a rigid gas-permeable contact lens polymer, Fluoroperm 92, has been carried out using positron annihilation lifetime spectroscopy, gravimetric analysis and refractive index measurements. The water sorption in FP92 is non-Fickian, whereas for glucose sorption it changes to Fickian. Glucose molecules reduce the interaction of water molecules with the polymer, resulting in more free water than bound water. It is observed that lenses which contain more bulk-water are prone to lens dehydration and corneal desiccation. The present results indicate that, in case of diabetics, as the glucose level increases in the aqueous humor, there would be more free water than bound water, which increases the propensity for corneal desiccation. The change in refractive index with increase in glucose content indicates decrease in optical transparency of the material.

  18. A study of inter-crystallite spaces in some polycrystalline inorganic systems using positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Shantarovich, V. P.; Suzuki, T.; Ito, Y.; Kondo, K.; Gustov, V. W.; Melikhov, I. V.; Berdonosov, S. S.; Ivanov, L. N.; Yu, R. S.

    2007-02-01

    Positron annihilation lifetime spectroscopy (PALS) was used for calculation of number density and effective sizes of free volume holes (inter-crystallite spaces) in polycrystal CaSO 4, CaCO 3 (vaterit) and Ca 10(PO 4) 6(OH) 2 (apatite). The effect of substitution of two-valence Ca(II) for three-valence Eu(III) on annihilation characteristics of apatite, studied together with the data on thermo-stimulated luminescence (TSL) and low-temperature sorption of gas (N 2), helped to elucidate mechanism of positronium atom (Ps) localization in the free volume holes and perform corresponding calculations. It came out that PALS is more sensitive to inter-crystallite sites (10 16 cm -3) in polycrystallites than to the free volume holes in polymer glasses (10 19 cm -3). This is due to higher mobility of the precursor of localized Ps in crystallites.

  19. Lifetime risk of stroke and impact of hypertension: estimates from the adult health study in Hiroshima and Nagasaki.

    PubMed

    Takahashi, Ikuno; Geyer, Susan M; Nishi, Nobuo; Ohshita, Tomohiko; Takahashi, Tetsuya; Akahoshi, Masazumi; Fujiwara, Saeko; Kodama, Kazunori; Matsumoto, Masayasu

    2011-05-01

    Very few reports have been published on lifetime risk (LTR) of stroke by blood pressure (BP) group. This study included participants in the Radiation Effects Research Foundation Adult Health Study who have been followed up by biennial health examinations since 1958. We calculated the LTR of stroke for various BP-based groups among 7847 subjects who had not been diagnosed with stroke before the index age of 55 years using cumulative incidence analysis adjusting for competing risks. By 2003, 868 subjects had suffered stroke (512 (58.9%) were women and 542 (62.4%) experienced ischemic stroke). BP was a significant factor in determining risk of stroke for men and women, with distributions of cumulative risk for stroke significantly different across BP groups. The LTR of all-stroke for normotension (systolic BP/diastolic BP < 120/80 mm Hg), prehypertension (120-139/80-89 mm Hg), stage 1 hypertension (140-159/90-99 mm Hg) and stage 2 hypertension (> 160/100 mm Hg) were 13.8-16.9-25.8-25.8% in men and 16.0-19.9-24.0-30.5% in women, respectively (P < 0.001 among BP groups in both sexes). The estimates did not differ significantly (P = 0.16) between normotensive and prehypertensive subjects. One in five Japanese atomic bomb survivor subjects experienced stroke over their lifetime from the age of 55 years. Long-term stroke risks were elevated in those with hypertension (> 140/90 mm Hg) at any of the index ages of 45, 55, 65 and 75 years.

  20. Lifetime risk of stroke and impact of hypertension: estimates from the adult health study in Hiroshima and Nagasaki.

    PubMed

    Takahashi, Ikuno; Geyer, Susan M; Nishi, Nobuo; Ohshita, Tomohiko; Takahashi, Tetsuya; Akahoshi, Masazumi; Fujiwara, Saeko; Kodama, Kazunori; Matsumoto, Masayasu

    2011-05-01

    Very few reports have been published on lifetime risk (LTR) of stroke by blood pressure (BP) group. This study included participants in the Radiation Effects Research Foundation Adult Health Study who have been followed up by biennial health examinations since 1958. We calculated the LTR of stroke for various BP-based groups among 7847 subjects who had not been diagnosed with stroke before the index age of 55 years using cumulative incidence analysis adjusting for competing risks. By 2003, 868 subjects had suffered stroke (512 (58.9%) were women and 542 (62.4%) experienced ischemic stroke). BP was a significant factor in determining risk of stroke for men and women, with distributions of cumulative risk for stroke significantly different across BP groups. The LTR of all-stroke for normotension (systolic BP/diastolic BP < 120/80 mm Hg), prehypertension (120-139/80-89 mm Hg), stage 1 hypertension (140-159/90-99 mm Hg) and stage 2 hypertension (> 160/100 mm Hg) were 13.8-16.9-25.8-25.8% in men and 16.0-19.9-24.0-30.5% in women, respectively (P < 0.001 among BP groups in both sexes). The estimates did not differ significantly (P = 0.16) between normotensive and prehypertensive subjects. One in five Japanese atomic bomb survivor subjects experienced stroke over their lifetime from the age of 55 years. Long-term stroke risks were elevated in those with hypertension (> 140/90 mm Hg) at any of the index ages of 45, 55, 65 and 75 years. PMID:21326305

  1. Molecular beam studies of elementary chemical processes.

    PubMed

    Lee, Y T

    1987-05-15

    The experimental investigation of elementary chemical reactions is presently in a very exciting period. The advance in modern microscopic experimental methods, especially crossed molecular beams and laser technology, has made it possible to explore the dynamics and mechanisms of important elementary chemical reactions in great detail. Through the continued accumulation of detailed and reliable knowledge about elementary reactions, we will be in a better position to understand, predict, and control many time-dependent macroscopic chemical processes that are important in nature or to human society. In addition, because of recent improvements in the accuracy of theoretical predictions based on large-scale ab initio quantum mechanical calculations, meaningful comparisons between theoretical and experimental findings have become possible. In the remaining years of the 20th century, there is no doubt that the experimental investigation of the dynamics and mechanisms of elementary chemical reactions will play a very important role in bridging the gap between the basic laws of mechanics and the real world of chemistry.

  2. Anomalous beam diffusion near beam-beam synchrobetatron resonances

    NASA Astrophysics Data System (ADS)

    Sen, Tanaji

    2012-10-01

    The diffusion process near low order synchrobetatron resonances driven by beam-beam interactions at a crossing angle is investigated. Macroscopic observables such as beam emittance, lifetime, and beam profiles are calculated. These are followed with detailed studies of microscopic quantities such as the evolution of the variance at several transverse amplitudes and single particle probability distribution functions. We present evidence to show that the observed diffusion is anomalous and the dynamics follows a non-Markovian continuous time random walk process. We derive a modified master equation to replace the Chapman-Kolmogorov equation in action-angle space and a fractional diffusion equation to describe the density evolution for this class of processes.

  3. Beam-foil-gas spectroscopy - A technique for studying steady-state non-equilibrium processes.

    NASA Technical Reports Server (NTRS)

    Bickel, W. S.; Veje, E.; Carriveau, G.; Anderson, N.

    1971-01-01

    When a thin foil is inserted in the beam of a beam-gas experiment, the beam particle state populations are driven far from their beam-gas equilibrium values. Downstream from the foil, the 'new beam' and gas species interact to produce a new equilibrium, usually different from the beam-gas equilibrium. Experimental results are presented to demonstrate this effect and to show how relative cross-section measurements can be used to study the beam-foil interaction.

  4. Direct correlation between the internal quantum efficiency and photoluminescence lifetime in undoped ZnO epilayers grown on Zn-polar ZnO substrates by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Takamizu, D.; Nishimoto, Y.; Akasaka, S.; Yuji, H.; Tamura, K.; Nakahara, K.; Onuma, T.; Tanabe, T.; Takasu, H.; Kawasaki, M.; Chichibu, S. F.

    2008-03-01

    The equivalent internal quantum efficiency (ηinteq) at 300K of the near-band-edge excitonic photoluminescence (PL) peak in ZnO epilayers grown by plasma-assisted molecular beam epitaxy on Zn-polar ZnO substrates was directly correlated with the PL lifetime (τPL) for the first time. This relation seems to be universal for O-polar ZnO films grown by other methods. Present homoepitaxial ZnO epilayers grown above 800°C exhibited atomically flat surfaces, and the best full-width-at-half-maximum value of (0002) ZnO x-ray diffraction ω-rocking curves was 17.6arcsec. The high-temperature growth also led to a long τPL of 1.2ns at 300K. As a result, a record high ηinteq value (9.6%) was eventually obtained under an excitation density of 5W/cm2 (He-Cd, 325.0nm). The homoepitaxial Zn-polar ZnO films grown by molecular beam epitaxy are coming to be used for p-n junction devices.

  5. BEAM-BEAM 2003 SUMMARY.

    SciTech Connect

    FISCHER,W.SEN,T.

    2003-05-19

    This paper summarizes the presentations and discussions of the Beam-Beam'03 workshop, held in Montauk, Long Island, from May 19 to 23, 2003. Presentations and discussions focused on halo generation from beam-beam interactions; beam-beam limits, especially coherent limits and their effects on existing and future hadron colliders; beam-beam compensation techniques, particularly for long-range interactions; and beam-beam study tools in theory, simulation, and experiment.

  6. A Computer Study of Beam Transport by Solenoids

    NASA Astrophysics Data System (ADS)

    Chan, Chun Fai; Lee, Edward P.

    1997-11-01

    Beam transport by solenoids provides an alternative to the use of electrostatic quadrupole arrays that has been less studied for applications to heavy ion fusion drivers. A 1-d code (named SALT, for Solenoid Applications to Linac Transport) has been developed to simulate the axisymmetric beam dynamics through a sequence of solenoids. The beam is modeled as a set of ringlets, with radius and momentum traced in the axial coordinate. Solenoid fringe field aberrations, envelope matching, phase space evolution and emittance growth are studied using relativistically correct equations that include the electric and magnetic fields of the beam. Initial application is to the transport of a 2 MeV, 31.10 Ampere of K^+ beam through a channel of strength 6 Tesla. This implies a line charge density of 10 μC/m, a factor of 40 above the realistic limit for electrostatic quadrupoles. A second application is to the focusing of a 20 MeV, 4 kA electron beam down to its emittance limit.

  7. Study of Long Range Beam-Beam Interaction Limit at CESR

    NASA Astrophysics Data System (ADS)

    Temnykh, Alexander; Sagan, David

    1997-05-01

    At CESR the counter rotating bunches share the same beam pipe and there is thus a long range beam-beam interaction (LRBBI) between the beams. It is well known that the strength of LRBBI depends on the beam intensity and on the separation between beams. We show with a simple numerical simulation that, in addition, the threshold of instability of a particle of one beam depends on the vertical size of the opposite beam. An increase of beam vertical size leads to an increase of the allowed beam intensity for a given separation. The recent experiments made at CESR and reported here confirmed this dependence as well as the early noticed fact that the LRBBI limit is due to vertical beam tail growth ( A. B. Temnykh, J. J. Welch and D. H. Rice, ``The Long Range Beam-Beam Interaction at CESR'', Proceedings of the 1993 IEEE Particle Accelerator Conference, p.2007).

  8. Lifetime carcinogenesis studies of amosite asbestos (Case No. 121-72-73-5) in Syrian golden hamsters (feed studies). Technical report series

    SciTech Connect

    Not Available

    1983-11-01

    Carcinogenesis studies of amosite asbestos were conducted by administering diets containing 1% of the asbestos in pellets from the conception of the mothers through the lifetime of male and female Syrian golden hamsters. Control groups consisted of 127 male and 126 female hamsters and the amosite asbestos group consisted of 252 male and 254 female hamsters. No adverse effect on body-weight gain or survival was observed from treatment with amosite asbestos. Neither of the amosite asbestos groups showed increased neoplasia in any organ or tissue compared to the control groups. Under the conditions of these studies, the ingestion of amosite asbestos at a level of 1% in the diet for their lifetime was not toxic and did not cause a carcinogenic response in male and female Syrian golden hamsters.

  9. Heavy flavor lifetimes and lifetime differences

    SciTech Connect

    Jonas Rademacker

    2003-09-17

    The authors give an overview of heavy flavour lifetime measurements, focusing on recent results from the Tevatron and the B factories. In the first part of this article we summarize the status and latest measurements of B-hadron lifetimes and lifetime ratios, including some recent result from the Tevatron and the B factories, and compare those results with the predictions from Heavy Quark Expansion (HQE). Future prospects for lifetime measurements at the B factories and the Tevatron are discussed. In the second part, we review the status and prospects of measuring the difference between the lifetimes of the two CP eigenstates in the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} system.

  10. Study of a final focus system for high intensity beams

    SciTech Connect

    Henestroza, Enrique; Eylon, Shmuel; Roy, Prabir K.; Yu, Simon S.; Bieniosek, Frank M.; Shuman, Derek B.; Waldron, William L.

    2004-06-01

    The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. The final focus scenario in an HIF driver consists of several large aperture quadrupole magnets followed by a drift section in which the beam space charge is neutralized by a plasma. This beam is required to hit a millimeter-sized target spot at the end of the drift section. The objective of the NTX experiments and associated theory and simulations is to study the various physical mechanisms that determine the final spot size (radius r{sub s}) at a given distance (f) from the end of the last quadrupole. In a fusion driver, f is the standoff distance required to keep the chamber wall and superconducting magnets properly protected. The NTX final quadrupole focusing system produces a converging beam at the entrance to the neutralized drift section where it focuses to a small spot. The final spot is determined by the conditions of the beam entering the quadrupole section, the beam dynamics in the magnetic lattice, and the plasma neutralization dynamics in the drift section. The main issues are the control of emittance growth due to high order fields from magnetic multipoles and image fields. In this paper, we will describe the theoretical and experimental aspects of the beam dynamics in the quadrupole lattice, and how these physical effects influence the final beam size. In particular, we present theoretical and experimental results on the dependence of final spot size on geometric aberrations and perveance.

  11. Nuclear photofission studies with monochromatic {gamma} ray beams

    SciTech Connect

    Csige, L.; Gulyas, J.; Habs, D.; Krasznahorkay, A.; Thirolf, P. G.; Tornyi, T. G.

    2012-07-09

    Two new research facilities will be ready for operation very soon (MEGa-Ray at Liver-more National Laboratory) or start construction (ELI-Nuclear Physics in Bucharest), both providing highly brilliant {gamma} beams with so far unprecedented properties via Compton backscattering of laser photons from a high-quality, relativistic electron beam. With these intense, monochromatic {gamma} beams, a new era of photonuclear physics will be enabled. A new research campaign is proposed to exploit the unprecedented properties of these highly-brilliant, novel {gamma} beams on highly-selective studies of extremely deformed nuclei in the multiple-humped potential energy landscape of the actinides via photofission. With the unique {gamma} beam bandwidth of {Delta}E/E = 10{sup -3}, we can aim at resolving individual resonances which could never be achieved so far due to the limited {gamma} bandwidth of bremsstrahlung beams. Exploratory, non-bremsstrahlung photofission experiments are going to be performed very soon at the HI{gamma}S facility (Duke University, USA) to investigate the fine structure of the sub-barrier transmission resonances of the actinides.

  12. Radiative lifetimes of the bound excited states of Pt-

    NASA Astrophysics Data System (ADS)

    Chartkunchand, K. C.; Kamińska, M.; Anderson, E. K.; Kristiansson, M. K.; Eklund, G.; Hole, O. M.; Nascimento, R. F.; Blom, M.; Björkhage, M.; Källberg, A.; Löfgren, P.; Reinhed, P.; Rosén, S.; Simonsson, A.; Thomas, R. D.; Mannervik, S.; Davis, V. T.; Neill, P. A.; Thompson, J. S.; Hanstorp, D.; Zettergren, H.; Cederquist, H.; Schmidt, H. T.

    2016-09-01

    The intrinsic radiative lifetimes of the 5 d106 s1/2 2S and 5 d96 s2 3/2 2D bound excited states in the platinum anion Pt-have been studied at cryogenic temperatures at the Double ElectroStatic Ion Ring Experiment (DESIREE) facility at Stockholm University. The intrinsic lifetime of the higher-lying 5 d106 s 1/2 2S state was measured to be 2.54 ±0.10 s , while only a lifetime in the range of 50-200 ms could be estimated for the 5 d96 s2 3/2 2D fine-structure level. The storage lifetime of the Pt- ion beam was measured to be a little over 15 min at a ring temperature of 13 K . The present study reports the lifetime of an atomic negative ion in an excited bound state with an electron configuration different from that of the ground state.

  13. Radiative lifetimes of the bound excited states of Pt-

    NASA Astrophysics Data System (ADS)

    Chartkunchand, K. C.; Kamińska, M.; Anderson, E. K.; Kristiansson, M. K.; Eklund, G.; Hole, O. M.; Nascimento, R. F.; Blom, M.; Björkhage, M.; Källberg, A.; Löfgren, P.; Reinhed, P.; Rosén, S.; Simonsson, A.; Thomas, R. D.; Mannervik, S.; Davis, V. T.; Neill, P. A.; Thompson, J. S.; Hanstorp, D.; Zettergren, H.; Cederquist, H.; Schmidt, H. T.

    2016-09-01

    The intrinsic radiative lifetimes of the 5 d106 s 1/2 2S and 5 d96 s2 3/2 2D bound excited states in the platinum anion Pt-have been studied at cryogenic temperatures at the Double ElectroStatic Ion Ring Experiment (DESIREE) facility at Stockholm University. The intrinsic lifetime of the higher-lying 5 d106 s 1/2 2S state was measured to be 2.54 ±0.10 s , while only a lifetime in the range of 50-200 ms could be estimated for the 5 d96 s2 3/2 2D fine-structure level. The storage lifetime of the Pt- ion beam was measured to be a little over 15 min at a ring temperature of 13 K . The present study reports the lifetime of an atomic negative ion in an excited bound state with an electron configuration different from that of the ground state.

  14. Diffusion Simulation and Lifetime Calculation at RHIC

    SciTech Connect

    Abreu,N.P.; Fischer, W.; Luo, Y.; Robert-Demolaize, G.

    2009-01-02

    The beam lifetime is an important parameter for any storage ring. For protons in RHIC it is dominated by the non-linear nature of the head-on collisions that causes the particles to diffuse outside the stable area in phase space. In this report we show results from diffusion simulation and lifetime calculation for the 2006 and 2008 polarized proton runs in RHIC.

  15. Studies of beam dynamics in relativistic klystron two-beam accelerators

    SciTech Connect

    Lidia, Steven M.

    1999-11-01

    Two-beam accelerators (TBAs) based upon free-electron lasers (FELs) or relativistic klystrons (RK-TBAs) have been proposed as efficient power sources for next generation high-energy linear colliders. Studies have demonstrated the possibility of building TBAs from X-band ({approximately}8-12 GHz) through Ka band ({approximately} 30-35 GHz) frequency regions. Provided that further prototyping shows stable beam propagation with minimal current loss and production of good quality, high-power rf fields, this technology is compatible with current schemes for electron-positron colliders in the multi-TeV center-of-mass scale. A new method of simulating the beam dynamics in accelerators of this type has been developed in this dissertation. There are three main components to this simulation. The first is a tracking algorithm to generate nonlinear transfer maps for pushing noninteracting particles through the external fields. The second component is a 3D Particle-In-Cell (PIC) algorithm that solves a set of Helmholtz equations for the self-fields, including the conducting boundary condition, and generates impulses that are interleaved with the nonlinear maps by means of a split-operation algorithm. The Helmholtz equations are solved by a multi-grid algorithm. The third component is an equivalent circuit equation solver that advances the modal rf cavity fields in time due to excitation by the modulated beam. The RTA project is described, and the simulation code is used to design the latter portions of the experiment. Detailed calculations of the beam dynamics and of the rf cavity output are presented and discussed. A beamline design is presented that will generate nearly 1.2 GW of power from 40 input, gain, and output rv cavities over a 10 m distance. The simulations show that beam current losses are acceptable, and that longitudinal and transverse focusing techniques are sufficient capable of maintaining a high degree of beam quality along the entire beamline. Additional

  16. Lifetime toxicity/carcinogenicity study of FD & C Red No. 3 (erythrosine) in rats.

    PubMed

    Borzelleca, J F; Capen, C C; Hallagan, J B

    1987-10-01

    FD & C Red No. 3 was fed to Charles River CD rats as a dietary admixture in two long-term toxicity/carcinogenicity studies. The studies consisted of an in utero and an F1 phase. In the former, the compound was administered to five groups of the F0 generation rats (60 of each sex/group) at levels of 0.0, 0.0, 0.1, 0.5 or 1.0% ('original study') and 0.0 or 4.0% ('high-dose study'). The concurrent control groups received the basal diet. After random selection of the F1 animals, the long-term phase was initiated using the same dietary levels and 70 rats of each sex/group, including the three control groups. Rats were exposed for a maximum of 30 months. No compound-related effects were noted in the in utero phase. Mean body weights of the female F1 rats on 4.0% FD & C Red No. 3 (3029 mg/kg/body weight/day) were significantly lower than those of controls (P less than 0.01) throughout the study. Food consumption increased in all treated groups in a dose-related manner. There were no significant effects on the haematology, serum chemistry and urinalysis and no compound-related effects on survival. In male rats receiving 4.0% FD & C Red No. 3 (2464 mg/kg/day) thyroid weights were increased, with a mean weight of 92 mg compared to 44 mg for controls, and statistically significant increases in the incidence of thyroid follicular cell hypertrophy, hyperplasia and adenomas were recorded. A numerically increased incidence of thyroid follicular adenomas in female rats given 0.5, 1.0 or 4.0% FD & C Red No. 3 was not statistically significant. The no-observed-adverse-effect levels established in these studies were 0.5% (251 mg/kg/day) for male rats and 1.0% (641 mg/kg/day) for females.

  17. Lifetime overweight and obesity and body composition in adulthood: the 1982 Pelotas (Brazil) birth cohort study.

    PubMed

    Callo, Gabriela; Gigante, Denise Pretucci; Barros, Fernando C; Horta, Bernardo Lessa

    2016-01-01

    This study aimed to assess the association between overweight/obesity at different moments in the life cycle and body composition in early adulthood. Data were used from the 1982 Pelotas (Brazil) birth cohort study, which has followed live born children of families residing in the urban area of Pelotas at different ages. At 30 years of age, 3,701 cohort members were interviewed and body composition was assessed using Bod Pod, 2,219 cohort members had at least one weight and height measurement taken in the three periods (childhood, adolescence, and adulthood), 24% never presented overweight, and 68.6% were never classified as obese. Elevated body mass index (BMI) and percent body fat at 30 years of age were associated with individuals classified as overweight in all three periods or in adolescence and adulthood, while those with overweight/obesity only in childhood or adolescence showed mean BMI and percent body fat similar to those who had never presented overweight/obesity. The results indicate the benefit of early interruption of overweight/obesity.

  18. RADIATIVE LIFETIMES OF V I AND V II

    SciTech Connect

    Den Hartog, E. A.; Lawler, J. E.; Wood, M. P. E-mail: jelawler@wisc.edu

    2014-11-01

    New radiative lifetimes are reported for 168 levels of V I ranging in energy from 18086 cm{sup –1} to 47702 cm{sup –1}, and for 31 levels of V II ranging in energy from 34593 cm{sup –1} to 47420 cm{sup –1}. These lifetimes are measured using time-resolved laser-induced fluorescence on a slow atomic/ionic beam as part of an ongoing study of the radiative properties of the iron group elements. All but two of the V II lifetimes have been measured before using modern laser-based methods, but a large fraction of the V I lifetimes are reported here for the first time. Comparison to earlier measurements is discussed. These new lifetimes are, for the most part, accurate to ±5%. They will be combined with branching fraction measurements to produce a large set of transition probabilities for V I and V II which are needed by the astrophysics community for stellar abundance determinations.

  19. Study of longitudinal dynamics in space-charge dominated beams

    NASA Astrophysics Data System (ADS)

    Tian, Kai

    from the 6-D phase space measurement has been used as initial conditions in computer simulations in order to explore the cause of discrepancies we have observed earlier between the experimental and theoretical models. After extensive simulation studies, we find that the beam loss inside the perturbation due to mismatch or misalignment is an important factor that needs to be included in the models for better reliability.

  20. SU-E-T-635: Quantitative Study On Beam Flatness Variation with Beam Energy Change

    SciTech Connect

    Li, J S; Eldib, A; Ma, C; Lin, M

    2014-06-15

    Purpose: Beam flatness check has been proposed for beam energy check for photon beams with flattering filters. In this work, beam flatness change with beam energy was investigated quantitatively using the Monte Carlo method and its significance was compared with depth dose curve change. Methods: Monte Carlo simulations for a linear accelerator with flattering filter were performed with different initial electron energies for photon beams of 6MV and 10MV. Dose calculations in a water phantom were then perform with the phase space files obtained from the simulations. The beam flatness was calculated based on the dose profile at 10 cm depth for all the beams with different initial electron energies. The percentage depth dose (PDD) curves were also analyzed. The dose at 10cm depth (D10) and the ratio of the dose at 10cm and 20cm depth (D10/D20) and their change with the beam energy were calculated and compared with the beam flatness variation. Results: It was found that the beam flatness variation with beam energy change was more significant than the change of D10 and the ratio between D10 and D20 for both 6MV and 10MV beams. Half MeV difference on the initial electron beam energy brought in at least 20% variation on the beam flatness but only half percent change on the ratio of D10 and D20. The change of D10 or D20 alone is even less significant. Conclusion: The beam energy impact on PDD is less significant than that on the beam flatness. If the PDD is used for checking the beam energy, uncertainties of the measurement could possibly disguise its change. Beam flatness changes more significantly with beam energy and therefore it can be used for monitoring the energy change for photon beams with flattering filters. However, other factors which may affect the beam flatness should be watched as well.

  1. Beam-beam interaction study of medium energy eRHIC

    SciTech Connect

    Hao,Y.; Litvinenko, V. N.; Ptitsyn, V.

    2009-07-15

    Medium Energy eRHIC (MeRHIC), the first stage design of eRHIC, includes a multi-pass ERL that provides 4GeV high quality electron beam to collide with the ion beam of RHIC. It delivers a minimum luminosity of 10{sup 32} cm{sup -2}s{sup -1}. Beam-beam effects present one of major factors limiting the luminosity of colliders. In this paper, both beam-beam effects on the electron beam and the proton beam in MeRHIC are investigated. The beam-beam interaction can induce a head-tail type instability of the proton beam referred to as the kink instability. Thus, beam stability conditions should be established to avoid proton beam loss. Also, the electron beam transverse disruption by collisions has to be evaluated to ensure that the beam quality is good enough for the energy recovery pass. The relation of proton beam stability, electron disruption and consequential luminosity are carried out after thorough discussion.

  2. Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium

    PubMed Central

    Stringer, S; Minică, C C; Verweij, K J H; Mbarek, H; Bernard, M; Derringer, J; van Eijk, K R; Isen, J D; Loukola, A; Maciejewski, D F; Mihailov, E; van der Most, P J; Sánchez-Mora, C; Roos, L; Sherva, R; Walters, R; Ware, J J; Abdellaoui, A; Bigdeli, T B; Branje, S J T; Brown, S A; Bruinenberg, M; Casas, M; Esko, T; Garcia-Martinez, I; Gordon, S D; Harris, J M; Hartman, C A; Henders, A K; Heath, A C; Hickie, I B; Hickman, M; Hopfer, C J; Hottenga, J J; Huizink, A C; Irons, D E; Kahn, R S; Korhonen, T; Kranzler, H R; Krauter, K; van Lier, P A C; Lubke, G H; Madden, P A F; Mägi, R; McGue, M K; Medland, S E; Meeus, W H J; Miller, M B; Montgomery, G W; Nivard, M G; Nolte, I M; Oldehinkel, A J; Pausova, Z; Qaiser, B; Quaye, L; Ramos-Quiroga, J A; Richarte, V; Rose, R J; Shin, J; Stallings, M C; Stiby, A I; Wall, T L; Wright, M J; Koot, H M; Paus, T; Hewitt, J K; Ribasés, M; Kaprio, J; Boks, M P; Snieder, H; Spector, T; Munafò, M R; Metspalu, A; Gelernter, J; Boomsma, D I; Iacono, W G; Martin, N G; Gillespie, N A; Derks, E M; Vink, J M

    2016-01-01

    Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40–48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13–20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10−8) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use. PMID:27023175

  3. Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium.

    PubMed

    Stringer, S; Minică, C C; Verweij, K J H; Mbarek, H; Bernard, M; Derringer, J; van Eijk, K R; Isen, J D; Loukola, A; Maciejewski, D F; Mihailov, E; van der Most, P J; Sánchez-Mora, C; Roos, L; Sherva, R; Walters, R; Ware, J J; Abdellaoui, A; Bigdeli, T B; Branje, S J T; Brown, S A; Bruinenberg, M; Casas, M; Esko, T; Garcia-Martinez, I; Gordon, S D; Harris, J M; Hartman, C A; Henders, A K; Heath, A C; Hickie, I B; Hickman, M; Hopfer, C J; Hottenga, J J; Huizink, A C; Irons, D E; Kahn, R S; Korhonen, T; Kranzler, H R; Krauter, K; van Lier, P A C; Lubke, G H; Madden, P A F; Mägi, R; McGue, M K; Medland, S E; Meeus, W H J; Miller, M B; Montgomery, G W; Nivard, M G; Nolte, I M; Oldehinkel, A J; Pausova, Z; Qaiser, B; Quaye, L; Ramos-Quiroga, J A; Richarte, V; Rose, R J; Shin, J; Stallings, M C; Stiby, A I; Wall, T L; Wright, M J; Koot, H M; Paus, T; Hewitt, J K; Ribasés, M; Kaprio, J; Boks, M P; Snieder, H; Spector, T; Munafò, M R; Metspalu, A; Gelernter, J; Boomsma, D I; Iacono, W G; Martin, N G; Gillespie, N A; Derks, E M; Vink, J M

    2016-01-01

    Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40-48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13-20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10(-8)) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use. PMID:27023175

  4. Charge carrier transport and lifetimes in n-type and p-type phosphorene as 2D device active materials: an ab initio study

    NASA Astrophysics Data System (ADS)

    Tea, E.; Hin, C.

    In this work, we provide a detailed analysis of phosphorene performance as n-type and p-type active materials. The study is based on first principles calculation of phosphorene electronic structure, and resulting electron and hole scattering rates and lifetimes. Emphasis is put on extreme regimes commonly found in semiconductor devices, i.e. high electric fields and heavy doping, where impact ionization and Auger recombination can occur. We found that electron-initiated impact ionization is weaker than the hole-initiated process, when compared to carrier-phonon interaction rates, suggesting resilience to impact ionization initiated breakdown. Moreover, calculated minority electron lifetimes are limited by radiative recombination only, not by Auger processes, suggesting that phosphorene could achieve good quantum efficiencies in optoelectronic devices. The provided scattering rates and lifetimes are critical input data for the modeling and understanding of phosphorene-based device physics.

  5. Charge carrier transport and lifetimes in n-type and p-type phosphorene as 2D device active materials: an ab initio study.

    PubMed

    Tea, E; Hin, C

    2016-08-10

    In this work, we provide a detailed analysis of phosphorene's performance as an n-type and p-type active material. This study is based on first principles calculations of the phosphorene electronic structure, and the resulting electron and hole scattering rates and lifetimes. Emphasis is put on extreme regimes commonly found in semiconductor devices, i.e. high electric fields and heavy doping, where impact ionization and Auger recombination can occur. We found that electron-initiated impact ionization is weaker than the hole-initiated process, when compared to carrier-phonon interaction rates, suggesting resilience to impact ionization initiated breakdown. Moreover, calculated minority electron lifetimes are limited by radiative recombination only, not by Auger processes, suggesting that phosphorene could achieve good quantum efficiencies in optoelectronic devices. The provided scattering rates and lifetimes are critical input data for the modeling and understanding of phosphorene-based device physics.

  6. Charge carrier transport and lifetimes in n-type and p-type phosphorene as 2D device active materials: an ab initio study.

    PubMed

    Tea, E; Hin, C

    2016-08-10

    In this work, we provide a detailed analysis of phosphorene's performance as an n-type and p-type active material. This study is based on first principles calculations of the phosphorene electronic structure, and the resulting electron and hole scattering rates and lifetimes. Emphasis is put on extreme regimes commonly found in semiconductor devices, i.e. high electric fields and heavy doping, where impact ionization and Auger recombination can occur. We found that electron-initiated impact ionization is weaker than the hole-initiated process, when compared to carrier-phonon interaction rates, suggesting resilience to impact ionization initiated breakdown. Moreover, calculated minority electron lifetimes are limited by radiative recombination only, not by Auger processes, suggesting that phosphorene could achieve good quantum efficiencies in optoelectronic devices. The provided scattering rates and lifetimes are critical input data for the modeling and understanding of phosphorene-based device physics. PMID:27479904

  7. A Case Study in Proton Pencil-Beam Scanning Delivery

    SciTech Connect

    Kooy, Hanne M.; Clasie, Benjamin M.; Lu, H.-M.; Madden, Thomas M.; Bentefour, Hassan; Depauw, Nicolas M.S.; Adams, Judy A.; Trofimov, Alexei V.; Demaret, Denis; Delaney, Thomas F.; Flanz, Jacob B.

    2010-02-01

    Purpose: We completed an implementation of pencil-beam scanning (PBS), a technology whereby a focused beam of protons, of variable intensity and energy, is scanned over a plane perpendicular to the beam axis and in depth. The aim of radiotherapy is to improve the target to healthy tissue dose differential. We illustrate how PBS achieves this aim in a patient with a bulky tumor. Methods and Materials: Our first deployment of PBS uses 'broad' pencil-beams ranging from 20 to 35 mm (full-width-half-maximum) over the range interval from 32 to 7 g/cm{sup 2}. Such beam-brushes offer a unique opportunity for treating bulky tumors. We present a case study of a large (4,295 cc clinical target volume) retroperitoneal sarcoma treated to 50.4 Gy relative biological effectiveness (RBE) (presurgery) using a course of photons and protons to the clinical target volume and a course of protons to the gross target volume. Results: We describe our system and present the dosimetry for all courses and provide an interdosimetric comparison. Discussion: The use of PBS for bulky targets reduces the complexity of treatment planning and delivery compared with collimated proton fields. In addition, PBS obviates, especially for cases as presented here, the significant cost incurred in the construction of field-specific hardware. PBS offers improved dose distributions, reduced treatment time, and reduced cost of treatment.

  8. Theoretical study of longitudinal beam splitting and related phenomena

    SciTech Connect

    Ellison, J.; Shih, H.J.; Kummer, M.

    1993-10-01

    A recent experiment at the Indiana University Cyclotron Facility (IUCF) with electron cooling showed that rf phase modulation near 1:1 resonance leads to longitudinal beam splitting. Here we explain this by applying the method of averaging, a powerful tool from the study of dynamical systems, to the underlying equation of motion -- a pendulum equation with small damping and periodic forcing. The beam splitting is explained by showing that the associated Poincare map has two attracting fixed points, each with a well-defined basin of attraction. Our approach can be immediately applied to other accelerator physics problems governed by a similar equation.

  9. Beam Breakup Studies for New Cryo-Unit

    SciTech Connect

    S. Ahmed, I. Shin, R. Kazimi, F. Marhauser ,F. Hannon ,G. Krafft ,B. Yunn ,A. Hofler

    2011-03-01

    In this paper, we report the numerical simulations of cumulative beam breakup studies for a new cryo-unit for booster design at Jefferson lab. The system consists of two 1-cell and one 7-cell superconducting RF cavities. Combining two 1-cell into a 2-cell together with a 7-cell is also an option. Simulations have been performed using the 2-dimensional time-domain code. The 1-cell+1-cell+7-cell combination confirms beam stability, however, the arrangement 2-cell+7-cell shows instability.

  10. Fermilab Booster Transition Crossing Simulations and Beam Studies

    SciTech Connect

    Bhat, C. M.; Tan, C. Y.

    2016-01-01

    The Fermilab Booster accelerates beam from 400 MeV to 8 GeV at 15 Hz. In the PIP (Proton Improvement Plan) era, it is required that Booster deliver 4.2 x $10^{12}$ protons per pulse to extraction. One of the obstacles for providing quality beam to the users is the longitudinal quadrupole oscillation that the beam suffers from right after transition. Although this oscillation is well taken care of with quadrupole dampers, it is important to understand the source of these oscillations in light of the PIP II requirements that require 6.5 x $10^{12}$ protons per pulse at extraction. This paper explores the results from machine studies, computer simulations and solutions to prevent the quadrupole oscillations after transition.

  11. Spheromak Energy Transport Studies via Neutral Beam Injection

    SciTech Connect

    McLean, H S; Hill, D N; Wood, R D; Jayakumar, J; Pearlstein, L D

    2008-02-11

    Results from the SSPX spheromak experiment provide strong motivation to add neutral beam injection (NBI) heating. Such auxiliary heating would significantly advance the capability to study the physics of energy transport and pressure limits for the spheromak. This LDRD project develops the physics basis for using NBI to heat spheromak plasmas in SSPX. The work encompasses three activities: (1) numerical simulation to make quantitative predictions of the effect of adding beams to SSPX, (2) using the SSPX spheromak and theory/modeling to develop potential target plasmas suitable for future application of neutral beam heating, and (3) developing diagnostics to provide the measurements needed for transport calculations. These activities are reported in several publications.

  12. Theoretical studies of a molecular beam generator

    NASA Technical Reports Server (NTRS)

    Heinbockel, John

    1994-01-01

    At present no adequate computer code exists for predicting the effects of thermal nonequilibrium on the flow quality of a converging-diverging N2 nozzle. It is the purpose of this research to develop such a code and then perform parametric studies to determine the effects of intermolecular forces (high gas pressure) and thermal nonequilibrium (the splitting of temperature into a vibrational and rotational-translational excitation) upon the flow quality. The two models to be compared are given. Appendix A contains nomenclature and additional relationships.

  13. Vibrational lifetimes of hydrogen on lead films: an ab initio molecular dynamics with electronic friction (AIMDEF) study.

    PubMed

    Saalfrank, Peter; Juaristi, J I; Alducin, M; Blanco-Rey, M; Muiño, R Díez

    2014-12-21

    Using density functional theory and Ab Initio Molecular Dynamics with Electronic Friction (AIMDEF), we study the adsorption and dissipative vibrational dynamics of hydrogen atoms chemisorbed on free-standing lead films of increasing thickness. Lead films are known for their oscillatory behaviour of certain properties with increasing thickness, e.g., energy and electron spillout change in discontinuous manner, due to quantum size effects [G. Materzanini, P. Saalfrank, and P. J. D. Lindan, Phys. Rev. B 63, 235405 (2001)]. Here, we demonstrate that oscillatory features arise also for hydrogen when chemisorbed on lead films. Besides stationary properties of the adsorbate, we concentrate on finite vibrational lifetimes of H-surface vibrations. As shown by AIMDEF, the damping via vibration-electron hole pair coupling dominates clearly over the vibration-phonon channel, in particular for high-frequency modes. Vibrational relaxation times are a characteristic function of layer thickness due to the oscillating behaviour of the embedding surface electronic density. Implications derived from AIMDEF for frictional many-atom dynamics, and physisorbed species will also be given. PMID:25527952

  14. In vivo detection of oral epithelial cancer using endogenous fluorescence lifetime imaging: a pilot human study (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jo, Javier A.; Hwang, Dae Yon; Palma, Jorge; Cheng, Shuna; Cuenca, Rodrigo; Malik, Bilal; Jabbour, Joey; Cheng, Lisa; Wright, John; Maitland, Kristen

    2016-03-01

    Endogenous fluorescence lifetime imaging (FLIM) provides direct access to the concomitant functional and biochemical changes accompanying tissue transition from benign to precancerous and cancerous. Since FLIM can noninvasively measure different and complementary biomarkers of precancer and cancer, we hypothesize that it will aid in clinically detecting early oral epithelial cancer. Our group has recently demonstrated the detection of benign from premalignant and malignant lesions based on endogenous multispectral FLIM in the hamster cheek-pouch model. Encouraged by these positive preliminary results, we have developed a handheld endoscope capable of acquiring multispectral FLIM images in real time from the oral mucosa. This novel FLIM endoscope is being used for imaging clinically suspicious pre-malignant and malignant lesions from patients before undergoing tissue biopsy for histopathological diagnosis of oral epithelial cancer. Our preliminary results thus far are already suggesting the potential of endogenous FLIM for distinguishing a variety of benign lesions from advanced dysplasia and squamous cell carcinoma (SCC). To the best of out knowledge, this is the first in vivo human study aiming to demonstrate the ability to predict the true malignancy of clinically suspicious lesions using endogenous FLIM. If successful, the resulting clinical tool will allow noninvasive real-time detection of epithelial precancerous and cancerous lesions in the oral mucosa and could potentially be used to assist at every step involved on the clinical management of oral cancer patients, from early screening and diagnosis, to treatment and monitoring of recurrence.

  15. Vibrational lifetimes of hydrogen on lead films: An ab initio molecular dynamics with electronic friction (AIMDEF) study

    SciTech Connect

    Saalfrank, Peter; Juaristi, J. I.

    2014-12-21

    Using density functional theory and Ab Initio Molecular Dynamics with Electronic Friction (AIMDEF), we study the adsorption and dissipative vibrational dynamics of hydrogen atoms chemisorbed on free-standing lead films of increasing thickness. Lead films are known for their oscillatory behaviour of certain properties with increasing thickness, e.g., energy and electron spillout change in discontinuous manner, due to quantum size effects [G. Materzanini, P. Saalfrank, and P. J. D. Lindan, Phys. Rev. B 63, 235405 (2001)]. Here, we demonstrate that oscillatory features arise also for hydrogen when chemisorbed on lead films. Besides stationary properties of the adsorbate, we concentrate on finite vibrational lifetimes of H-surface vibrations. As shown by AIMDEF, the damping via vibration-electron hole pair coupling dominates clearly over the vibration-phonon channel, in particular for high-frequency modes. Vibrational relaxation times are a characteristic function of layer thickness due to the oscillating behaviour of the embedding surface electronic density. Implications derived from AIMDEF for frictional many-atom dynamics, and physisorbed species will also be given.

  16. Psychosocial aetiology of chronic disease: a pragmatic approach to the assessment of lifetime affective morbidity in an EPIC component study

    PubMed Central

    Surtees, P; Wainwright, N; Brayne, C

    2000-01-01

    OBJECTIVES—The Health and Life Experiences Questionnaire (HLEQ) was developed for use in a prospective cohort study of 25 000 men and women living in Norfolk and forms a component study of the European Prospective Investigation into Cancer and Nutrition (EPIC). The HLEQ includes an assessment of mood status over the life course allowing a limited capacity for the imposition of diagnostic criteria to enable eventual evaluation of mental health status for chronic disease outcomes. This paper reports estimates of HLEQ Major Depressive Disorder (MDD) prevalence and compares them with those obtained through interviewer-based methods. In addition evidence for the impact of recall, clustering or cohort effects on these estimates are examined.
PARTICIPANTS—3491 eligible respondents to EPIC in Norfolk, aged 45-74 years, recruited from the first five general practices who completed the HLEQ.
MAIN RESULTS—MDD prevalence estimates were found to be closely comparable to those obtained recently (by interview) in the UK and to those lifetime MDD rates determined through international studies. Risk of MDD onset was found to vary with age as expected from earlier studies using interviewer-based assessments. Limited evidence was found to show that the distribution of first onset MDD episodes were compressed during the immediate pre-assessment period. Results were also consistent with previous evidence demonstrating the raised risk of MDD among women and of the decline in gender differences with advancing age.
CONCLUSIONS—These results suggest that estimates of putative MDD diagnostic status, derived through the HLEQ, and of associated demographic risk are similar to those derived by more intensive and costly assessment methods. Implications for the future study of MDD both as an outcome and as a risk factor for chronic disease are discussed.


Keywords: depression; epidemiology; prevalence PMID:10715744

  17. Fast beam studies of free radical photodissociation

    SciTech Connect

    Cyr, D R

    1993-11-01

    The photodissociation of free radicals is studied in order to characterize the spectroscopy and dissociation dynamics of the dissociative electronic states in these species. To accomplish this, a novel method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with a highly complementary form of photofragment translational spectroscopy. The optical spectroscopy of transitions to dissociative states is determined by monitoring the total photofragment yield as a function of dissociation photon energy. Branching ratios to various product channels, internal energy distributions of the fragments, bond dissociation energies, and the translational energy-dependent photofragment recoil angular distributions are then determined at selected excitation energies. A detailed picture of the dissociation dynamics can then be formulated, allowing insight concerning the interactions of potential energy surfaces involved in the dissociation. After an introduction to the concepts and techniques mentioned above, the experimental apparatus used in these experiments is described in detail. The basis and methods used in the treatment of data, especially in the dissociation dynamics experiments, are then put forward.

  18. Parametric study of beam refraction problems across laser anemometer windows

    NASA Technical Reports Server (NTRS)

    Owen, A. K.

    1986-01-01

    The experimenter is often required to view flows through a window with a different index of refraction than either the medium being observed or the medium that the laser anemometer is immersed in. The refraction that occurs at the window surfaces may lead to undesirable changes in probe volume position or beam crossing angle and can lead to partial or complete beam uncrossing. This report describes the results of a parametric study of this problem using a ray tracing technique to predict these changes. The windows studied were a flat plate and a simple cyclinder. For the flat-plate study: (1) surface thickness, (2) beam crossing angle, (3) bisecting line - surface normal angle, and (4) incoming beam plane surface orientation were varied. For the cylindrical window additional parameters were also varied: (1) probe volume immersion, (2) probe volume off-radial position, and (3) probe volume position out of the R-theta plane of the lens. A number of empirical correlations were deduced to aid the interested reader in determining the movement, uncrossing, and change in crossing angle for a particular situation.

  19. Study of a multi-beam accelerator driven thorium reactor

    SciTech Connect

    Ludewig, H.; Aronson, A.

    2011-03-01

    The primary advantages that accelerator driven systems have over critical reactors are: (1) Greater flexibility regarding the composition and placement of fissile, fertile, or fission product waste within the blanket surrounding the target, and (2) Potentially enhanced safety brought about by operating at a sufficiently low value of the multiplication factor to preclude reactivity induced events. The control of the power production can be achieved by vary the accelerator beam current. Furthermore, once the beam is shut off the system shuts down. The primary difference between the operation of an accelerator driven system and a critical system is the issue of beam interruptions of the accelerator. These beam interruptions impose thermo-mechanical loads on the fuel and mechanical components not found in critical systems. Studies have been performed to estimate an acceptable number of trips, and the value is significantly less stringent than had been previously estimated. The number of acceptable beam interruptions is a function of the length of the interruption and the mission of the system. Thus, for demonstration type systems and interruption durations of 1sec < t < 5mins, and t > 5mins 2500/yr and 50/yr are deemed acceptable. However, for industrial scale power generation without energy storage type systems and interruption durations of t < 1sec., 1sec < t < 10secs., 10secs < t < 5mins, and t > 5mins, the acceptable number of interruptions are 25000, 2500, 250, and 3 respectively. However, it has also been concluded that further development is required to reduce the number of trips. It is with this in mind that the following study was undertaken. The primary focus of this study will be the merit of a multi-beam target system, which allows for multiple spallation sources within the target/blanket assembly. In this manner it is possible to ameliorate the effects of sudden accelerator beam interruption on the surrounding reactor, since the remaining beams will still

  20. Measurement of short lifetimes in highly-charged ions using a two-foil target

    SciTech Connect

    Berry, H.G.; Dunford, R.W.; Gemmell, D.S.

    1995-08-01

    One of the frontiers in the study of the atomic physics of highly-charged ions is the measurement of lifetimes in the 100 fs to 10 ps regime. The standard technique for measuring lifetimes of states in highly-charged ions is the beam-foil time-of-flight method in which the intensity of an emission line is monitored as a function of the separation between the exciting foil and the portion of the beam being viewed by the detector. This method becomes increasingly difficult as the decay lengths of the states of interest become shorter. At a typical beam velocity of 10% of the speed of light, the beam travels 30 microns in a picosecond. The standard beam-foil time-of-flight method necessitates observation of the decay radiation within one or two decay lengths from the foil while preventing the detectors from observing the beam spot at the foil. For short-lived states this requires tight collimation of the detector with a resulting loss in solid angle. We are developing a method for measuring ultrashort atomic lifetimes utilizing a two-foil target. As a specific case to demonstrate the feasibility of our method, we are studying the decay of the 2 {sup 3}P{sub 2} level in helium-like Kr{sup 34+}. This level has a calculated lifetime of 9.5 ps which corresponds to a decay length of 380 {mu}m. For krypton, theory predicts that 90% of the 2 {sup 3}P{sub 2} states decay via M2 radiation to the ground state. A measurement of the lifetime of this state would contribute to an important current problem which concerns the understanding of atomic structure when both electron correlations and relativistic effects are simultaneously important.

  1. Low-energy beam transport studies supporting the Spallation Neutron Source 1-MW beam operationa

    SciTech Connect

    Han, Baoxi; Kalvas, T.; Tarvainen, O.; Welton, Robert F; Murray Jr, S N; Pennisi, Terry R; Santana, Manuel; Stockli, Martin P

    2012-01-01

    The H- injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the Spallation Neutron Source 1-MW beam operation with ~38 mA beam current in the linac at 60 Hz with a pulse length of up to ~1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: 1) inconsistent dependence of the post-RFQ beam current on the ion source tilt angle, and 2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.

  2. Commisioning of the second Tevatron electron lens and beam study results

    SciTech Connect

    Kamerdzhiev, V.; Fellenz, B.; Hively, R.; Kuznetsov, G.; Olson, M.; Pfeffer, H.; Saewert, G.; Scarpine, V.; Shiltsev, V.; Zhang, X.L.; /Fermilab

    2007-06-01

    In the framework of Fermilab's Beam-Beam Compensation (BBC) project, the 2nd Tevatron Electron Lens (TEL2) was installed in the Tevatron during Spring 2006 shutdown. It was successfully commissioned and a series of beam studies has been carried out in single bunch and all-bunch modes. The paper describes TEL2 commissioning and beam studies results.

  3. Measurement of the Neutron Lifetime by Counting Trapped Protons

    PubMed Central

    Wietfeldt, F. E.; Dewey, M. S.; Gilliam, D. M.; Nico, J. S.; Fei, X.; Snow, W. M.; Greene, G. L.; Pauwels, J.; Eykens, R.; Lamberty, A.; Van Gestel, J.

    2005-01-01

    We measured the neutron decay lifetime by counting in-beam neutron decay recoil protons trapped in a quasi-Penning trap. The absolute neutron beam fluence was measured by capture in a thin 6LiF foil detector with known efficiency. The combination of these measurements gives the neutron lifetime: τn = (886.8 ± 1.2 ± 3.2) s, where the first (second) uncertainty is statistical (systematic) in nature. This is the most precise neutron lifetime determination to date using an in-beam method. PMID:27308145

  4. Association of Overweight with the Prevalence of Lifetime Psychiatric Disorders and Suicidality: General Population-based Study in Korea

    PubMed Central

    2016-01-01

    Many epidemiological studies suggest that overweight is associated with an elevated risk of psychiatric disorders and suicidal tendency. However, findings vary across studies, and some have contradictory results. We investigated the relationship of overweight with a range of psychiatric disorders and suicidality in the Korean general population. A multistage cluster sampling design was adopted. A total of 6,022 participants aged 18–74 years completed face-to-face interviews (response rate: 78.7%) including assessment of psychiatric disorders, suicidality, and height and weight. Overweight (defined as body mass index of ≥ 25) was associated with an increase in the lifetime prevalence of depressive disorders (adjusted odds ratio [AOR] 1.38; 95% confidence interval [CI], 1.07–1.77), suicidal ideation (AOR, 1.42; 95% CI, 1.20–1.68), and suicidal plans (AOR, 1.44; 95% CI, 1.02–2.03), controlling for sociodemographic variables. Subgroup analysis found that the association between overweight and depressive disorders exists only in women aged 18–44 years (AOR, 1.75; 95% CI, 1.07–2.89) while the association of overweight with suicidal ideation (AOR, 2.08; 95% CI, 1.53–2.82) and suicide plans (AOR, 2.59; 95% CI, 1.25–5.37) existed only in men aged 18–44 years. Overweight was associated with increased odds of nicotine use disorders in women aged 18–44 years (AOR, 2.35; 95% CI, 1.02–5.43), but the association was in the opposite direction in men aged 45–74 years (AOR, 0.64; 95% CI, 0.43–0.94). In conclusion, overweight is related to various psychiatric disorders and suicidality in Korea. Policy makers and clinicians should pay more attention to the mental health of overweight individuals. PMID:27709862

  5. Computational challenges for beam-beam simulation for RHIC

    SciTech Connect

    Luo, Y.; Fischer, W.

    2010-10-01

    In this article we will review the computational challenges in the beam-beam simulation for the polarized proton run of the Relativistic Heavy Ion Collider (RHIC). The difficulties in our multi-particle and million turn tracking to calculate the proton beam lifetime and proton beam emittance growth due to head-on beam-beam interaction and head-on beam-beam compensation are presented and discussed. Solutions to obtain meaningful physics results from these trackings are proposed and tested. In the end we will present the progress in the benchmarking of the RHIC operational proton beam lifetime.

  6. The intense slow positron beam facility at the PULSTAR reactor and applications in nano-materials study

    SciTech Connect

    Liu, Ming; Moxom, Jeremy; Hawari, Ayman I.; Gidley, David W.

    2013-04-19

    An intense slow positron beam has been established at the PULSTAR nuclear research reactor of North Carolina State University. The slow positrons are generated by pair production in a tungsten moderator from gammarays produced in the reactor core and by neutron capture reactions in cadmium. The moderated positrons are electrostatically extracted and magnetically guided out of the region near the core. Subsequently, the positrons are used in two spectrometers that are capable of performing positron annihilation lifetime spectroscopy (PALS) and positron Doppler broadening spectroscopy (DBS) to probe the defect and free volume properties of materials. One of the spectrometers (e{sup +}-PALS) utilizes an rf buncher to produce a pulsed beam and has a timing resolution of 277 ps. The second spectrometer (Ps-PALS) uses a secondary electron timing technique and is dedicated to positronium lifetime measurements with an approximately 1 ns timing resolution. PALS measurements have been conducted in the e{sup +}-PALS spectrometer on a series of nano-materials including organic photovoltaic thin films, membranes for filtration, and polymeric fibers. These studies have resulted in understanding some critical issues related to the development of the examined nano-materials.

  7. Lifetime costs of cerebral palsy.

    PubMed

    Kruse, Marie; Michelsen, Susan Ishøy; Flachs, Esben Meulengracht; Brønnum-Hansen, Henrik; Madsen, Mette; Uldall, Peter

    2009-08-01

    This study quantified the lifetime costs of cerebral palsy (CP) in a register-based setting. It was the first study outside the US to assess the lifetime costs of CP. The lifetime costs attributable to CP were divided into three categories: health care costs, productivity costs, and social costs. The population analysed was retrieved from the Danish Cerebral Palsy Register, which covers the eastern part of the country and has registered about half of the Danish population of individuals with CP since 1950. For this study we analysed 2367 individuals with CP, who were born in 1930 to 2000 and were alive in 2000. The prevalence of CP in eastern Denmark was approximately 1.7 per 1000. Information on productivity and the use of health care was retrieved from registers. The lifetime cost of CP was about 860,000 euro for men and about 800,000 euro for women. The largest component was social care costs, particularly during childhood. A sensitivity analysis found that alterations in social care costs had a small effect, whereas lowering the discount rate from 5 to 3 per cent markedly increased total lifetime costs. Discounting decreases the value of costs in the future compared with the present. The high social care costs and productivity costs associated with CP point to a potential gain from labour market interventions that benefit individuals with CP. PMID:19416329

  8. Lifetime studies of 130nm nMOS transistors intended for long-duration, cryogenic high-energy physics experiments.

    SciTech Connect

    Hoff, J.R.; Arora, R.; Cressler, J.D.; Deptuch, G.W.; Gui, P.; Lourenco, N.E.; Wu, G.; Yarema, R.J.; /Fermilab

    2011-12-01

    Future neutrino physics experiments intend to use unprecedented volumes of liquid argon to fill a time projection chamber in an underground facility. To increase performance, integrated readout electronics should work inside the cryostat. Due to the scale and cost associated with evacuating and filling the cryostat, the electronics will be unserviceable for the duration of the experiment. Therefore, the lifetimes of these circuits must be well in excess of 20 years. The principle mechanism for lifetime degradation of MOSFET devices and circuits operating at cryogenic temperatures is via hot carrier degradation. Choosing a process technology that is, as much as possible, immune to such degradation and developing design techniques to avoid exposure to such damage are the goals. This requires careful investigation and a basic understanding of the mechanisms that underlie hot carrier degradation and the secondary effects they cause in circuits. In this work, commercially available 130nm nMOS transistors operating at cryogenic temperatures are investigated. The results show that the difference in lifetime for room temperature operation and cryogenic operation for this process are not great and the lifetimes at both 300K and at 77K can be projected to more than 20 years at the nominal voltage (1.5V) for this technology.

  9. The Lifetimes of Astronomers

    NASA Astrophysics Data System (ADS)

    Abt, Helmut A.

    2015-08-01

    For members of the American Astronomical Society, I collected data on their lifetimes from (1) 489 obituaries published in 1991-2015, (2) about 127 members listed as deceased but without published obituaries, and (3) a sample of AAS members without obituaries or not known to the AAS as being deceased. These show that the most frequent lifetimes is 85 years. Of 674 deceased members with known lifetimes, 11.0 ± 1.3% lived to be 90 or more years. In comparison to the astronomers, the most frequent lifetime for the general population is 77 years, showing that astronomers live an average of 8 years longer than the general population.

  10. Mercury Reduces Avian Reproductive Success and Imposes Selection: An Experimental Study with Adult- or Lifetime-Exposure in Zebra Finch

    PubMed Central

    Varian-Ramos, Claire W.; Swaddle, John P.; Cristol, Daniel A.

    2014-01-01

    Mercury is a global pollutant that biomagnifies in food webs, placing wildlife at risk of reduced reproductive fitness and survival. Songbirds are the most diverse branch of the avian evolutionary tree; many are suffering persistent and serious population declines and we know that songbirds are frequently exposed to mercury pollution. Our objective was to determine the effects of environmentally relevant doses of mercury on reproductive success of songbirds exposed throughout their lives or only as adults. The two modes of exposure simulated philopatric species versus dispersive species, and are particularly relevant because of the heightened mercury-sensitivity of developing nervous systems. We performed a dosing study with dietary methylmercury in a model songbird species, the zebra finch (Taeniopygia guttata), at doses from 0.3 – 2.4 parts per million. Birds were exposed to mercury either as adults only or throughout their lives. All doses of mercury reduced reproductive success, with the lowest dose reducing the number of independent offspring produced in one year by 16% and the highest dose, representing approximately half the lethal dose for this species, causing a 50% reduction. While mercury did not affect clutch size or survivorship, it had the most consistent effect on the proportion of chicks that fledged from the nest, regardless of mode of exposure. Among birds exposed as adults, mercury caused a steep increase in the latency to re-nest after loss of a clutch. Birds exposed for their entire lifetimes, which were necessarily the offspring of dosed parents, had up to 50% lower reproductive success than adult-exposed birds at low doses of methylmercury, but increased reproductive success at high doses, suggesting selection for mercury tolerance at the highest level of exposure. Our results indicate that mercury levels in prey items at contaminated sites pose a significant threat to populations of songbirds through reduced reproductive success. PMID

  11. Mercury reduces avian reproductive success and imposes selection: an experimental study with adult- or lifetime-exposure in zebra finch.

    PubMed

    Varian-Ramos, Claire W; Swaddle, John P; Cristol, Daniel A

    2014-01-01

    Mercury is a global pollutant that biomagnifies in food webs, placing wildlife at risk of reduced reproductive fitness and survival. Songbirds are the most diverse branch of the avian evolutionary tree; many are suffering persistent and serious population declines and we know that songbirds are frequently exposed to mercury pollution. Our objective was to determine the effects of environmentally relevant doses of mercury on reproductive success of songbirds exposed throughout their lives or only as adults. The two modes of exposure simulated philopatric species versus dispersive species, and are particularly relevant because of the heightened mercury-sensitivity of developing nervous systems. We performed a dosing study with dietary methylmercury in a model songbird species, the zebra finch (Taeniopygia guttata), at doses from 0.3 - 2.4 parts per million. Birds were exposed to mercury either as adults only or throughout their lives. All doses of mercury reduced reproductive success, with the lowest dose reducing the number of independent offspring produced in one year by 16% and the highest dose, representing approximately half the lethal dose for this species, causing a 50% reduction. While mercury did not affect clutch size or survivorship, it had the most consistent effect on the proportion of chicks that fledged from the nest, regardless of mode of exposure. Among birds exposed as adults, mercury caused a steep increase in the latency to re-nest after loss of a clutch. Birds exposed for their entire lifetimes, which were necessarily the offspring of dosed parents, had up to 50% lower reproductive success than adult-exposed birds at low doses of methylmercury, but increased reproductive success at high doses, suggesting selection for mercury tolerance at the highest level of exposure. Our results indicate that mercury levels in prey items at contaminated sites pose a significant threat to populations of songbirds through reduced reproductive success.

  12. Lifetimes of lunar satellite orbits

    NASA Technical Reports Server (NTRS)

    Meyer, Kurt W.; Buglia, James J.; Desai, Prasun N.

    1994-01-01

    The Space Exploration Initiative has generated a renewed interest in lunar mission planning. The lunar missions currently under study, unlike the Apollo missions, involve long stay times. Several lunar gravity models have been formulated, but mission planners do not have enough confidence in the proposed models to conduct detailed studies of missions with long stay times. In this report, a particular lunar gravitational model, the Ferrari 5 x 5 model, was chosen to determine the lifetimes for 100-km and 300-km perilune altitude, near-circular parking orbits. The need to analyze orbital lifetimes for a large number of initial orbital parameters was the motivation for the formulation of a simplified gravitational model from the original model. Using this model, orbital lifetimes were found to be heavily dependent on the initial conditions of the nearly circular orbits, particularly the initial inclination and argument of perilune. This selected model yielded lifetime predictions of less than 40 days for some orbits, and other orbits had lifetimes exceeding a year. Although inconsistencies and limitations are inherent in all existing lunar gravity models, primarily because of a lack of information about the far side of the moon, the methods presented in this analysis are suitable for incorporating the moon's nonspherical gravitational effects on the preliminary design level for future lunar mission planning.

  13. Study on astrophysical reactions using low-energy RI beams

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hidetoshi

    2009-10-01

    In recent years, low-energy RI beams can be produced in a good intensity and they have been used for studying many astrophysical reactions. One of the facilities producing low-energy RI beams is CRIB (CNS Radio-Isotope Beam separator) [1,2], an RI-beam separator of Center for Nuclear Study, University of Tokyo. Taking CRIB as an example, recent improvements on the RI-beam production and experimental results on astrophysical studies are presented. Several experimental approaches have been taken for the studies on astrophysical reactions.The feature of each method are discussed based on real measurements performed at CRIB. One is the direct method, applied for measurements of reactions such as (α,p) [3]. Another is the measurement of proton/alpha resonance scattering using the thick target method in inverse kinematics, by which we can obtain information on the resonances relevant in astrophysical reactions [4,5]. A recent fruitful result was from a measurement of proton resonance scattering using a ^7Be beam [5]. The energy level structure of ^8B, revealed by the experiment, is especially of interest as it is related with the ^7Be(p,γ) ^8B reaction, responsible for the production of ^8B neutrinos in the sun. We successfully determined parameters of resonances in ^8B below 6.7 MeV, which may affect the ^7Be(p,γ)^8B reaction rate at the solar temparature. Indirect methods, such as ANC and the Trojan Horse Method, were also used in some of the measurements.[4pt] [1] S. Kubono et al., Eur. Phys. J. A13 (2002) 217.[0pt] [2] Y. Yanagisawa et al., Nucl. Instrum. Meth. Phys. Res., Sect. A 539 (2005) 74.[0pt] [3] M. Notani et al., Nucl. Phys. A 764 (2004) 113c.[0pt] [4] T. Teranishi et al., Phys. Lett. B 650 (2007) 129.[0pt] [5] H. Yamaguchi et al., Phys. Lett. B 672 (2009) 230.

  14. A beam optics study of the biomedical beam line at a proton therapy facility

    NASA Astrophysics Data System (ADS)

    Yun, Chong Cheoul; Kim, Jong-Won

    2007-10-01

    A biomedical beam line has been designed for the experimental area of a proton therapy facility to deliver mm to sub-mm size beams in the energy range of 20-50 MeV using the TRANSPORT/TURTLE beam optics codes and a newly-written program. The proton therapy facility is equipped with a 230 MeV fixed-energy cyclotron and an energy selection system based on a degrader and slits, so that beam currents available for therapy decrease at lower energies in the therapeutic beam energy range of 70-230 MeV. The new beam line system is composed of an energy-degrader, two slits, and three quadrupole magnets. The minimum beam sizes achievable at the focal point are estimated for the two energies of 50 and 20 MeV. The focused FWHM beam size is approximately 0.3 mm with an expected beam current of 20 pA when the beam energy is reduced to 50 MeV from 100 MeV, and roughly 0.8 mm with a current of 10 pA for a 20 MeV beam.

  15. 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.

  16. Crossed-beam studies of the dynamics of radical reactions

    SciTech Connect

    Liu, K.

    1993-12-01

    The objective of this program is to characterize the detailed dynamics of elementary radical reactions and to provide a better understanding of radical reactivity in general. The radical beam is typically generated by a laser photolysis method. After colliding with the reacting molecule in a crossed-beam apparatus, the reaction product state distribution is interrogated by laser spectroscopic techniques. Several radicals of combustion significance, such as O, CH, OH, CN and NCO have been successfully generated and their collisional behavior at the state-to-state integral cross section level of detail has been studied in this manner. During the past year, the detection system has been converted from LIF to REMPI schemes, and the emphasis of this program shifted to investigate the product angular distributions. Both inelastic and reactive processes have been studied.

  17. Effect of Superalloy Substrate and Bond Coating on TBC Lifetime

    SciTech Connect

    Pint, Bruce A; Haynes, James A; Zhang, Ying

    2010-01-01

    Several different single-crystal superalloys were coated with different bond coatings to study the effect of composition on the cyclic oxidation lifetime of an yttria-stabilized zirconia (YSZ) top coating deposited by electron beam physical vapor deposition from a commercial source. Three different superalloys were coated with a 7 {micro}m Pt layer that was diffused into the surface prior to YSZ deposition. One of the superalloys, N5, was coated with a low activity, Pt-modified aluminide coating and Pt-diffusion coatings with 3 and 7 {micro}m of Pt. Three coatings of each type were furnace cycled to failure in 1 h cycles at 1150 C to assess average coating lifetime. The 7 {micro}m Pt diffusion coating on N5 had an average YSZ coating lifetime >50% higher than a Pt-modified aluminide coating on N5. Without a YSZ coating, the Pt-modified aluminide coating on N5 showed the typical surface deformation during cycling, however, the deformation was greatly reduced when constrained by the YSZ coating. The 3 {micro}m Pt diffusion coating had a similar average lifetime as the Pt-modified aluminide coating but a much wider scatter. The Pt diffusion bond coating on superalloy X4 containing Ti exhibited the shortest YSZ coating lifetime, this alloy-coating combination also showed the worst alumina scale adhesion without a YSZ coating. The third generation superalloy N6 exhibited the longest coating lifetime with a 7 {micro}m Pt diffusion coating.

  18. Study of high field superconducting solenoids for muon beam cooling

    SciTech Connect

    Kashikhin, V.V.; Barzi, E.; Kashikhin, V.S.; Lamm, Michael J.; Sadovskiy, Y.; Zlobin, Alexander V; /Fermilab

    2007-08-01

    The final beam cooling stages of a possible Muon Collider may require DC solenoid magnets with magnetic fields of 40-50 T in an aperture of 40-50 mm. In this paper we study possible solutions towards creating DC fields of that order using available superconductors. Several magnetic and mechanical designs, optimized for the maximum performance are presented and compared in terms of cost and size.

  19. Carrier lifetimes and interface recombination velocities in CdTe/Mg{sub x}Cd{sub 1−x}Te double heterostructures with different Mg compositions grown by molecular beam epitaxy

    SciTech Connect

    Liu, Shi; Lassise, Maxwell B.; Zhao, Yuan; Zhang, Yong-Hang; Zhao, Xin-Hao; Campbell, Calli M.

    2015-07-27

    The interface recombination velocities of CdTe/Mg{sub x}Cd{sub 1−x}Te double heterostructure (DH) samples with different CdTe layer thicknesses and Mg compositions are studied using time-resolved photoluminescence measurements. A lowest interface recombination velocity of 30 ± 10 cm/s has been measured for the CdTe/Mg{sub 0.46}Cd{sub 0.54}Te interface, and a longest carrier lifetime of 0.83 μs has been observed for the studied DHs. These values are very close to the best reported numbers for GaAs/AlGaAs DHs. The impact of carrier escape through thermionic emission over the MgCdTe barrier on the recombination process in the DHs is also studied.

  20. A Lifetime Prevalence of Comorbidity Between Bipolar Affective Disorder and Anxiety Disorders: A Meta-analysis of 52 Interview-based Studies of Psychiatric Population

    PubMed Central

    Nabavi, Behrouz; Mitchell, Alex J.; Nutt, David

    2015-01-01

    Background Bipolar affective disorder has a high rate of comorbidity with a multitude of psychiatric disorders and medical conditions. Among all the potential comorbidities, co-existing anxiety disorders stand out due to their high prevalence. Aims To determine the lifetime prevalence of comorbid anxiety disorders in bipolar affective disorder under the care of psychiatric services through systematic review and meta-analysis. Method Random effects meta-analyses were used to calculate the lifetime prevalence of comorbid generalised anxiety disorder, panic disorder, social anxiety disorder, specific phobia, agoraphobia, obsessive compulsive disorder and posttraumatic stress disorder in bipolar affective disorder. Results 52 studies were included in the meta-analysis. The rate of lifetime comorbidity was as follows: panic disorder 16.8% (95% CI 13.7–20.1), generalised anxiety disorder 14.4% (95% CI 10.8–18.3), social anxiety disorder13.3% (95% CI 10.1–16.9), post-traumatic stress disorder 10.8% (95% CI 7.3–14.9), specific phobia 10.8% (95% CI 8.2–13.7), obsessive compulsive disorder 10.7% (95% CI 8.7–13.0) and agoraphobia 7.8% (95% CI 5.2–11.0). The lifetime prevalence of any anxiety disorders in bipolar disorder was 42.7%. Conclusions Our results suggest a high rate of lifetime concurrent anxiety disorders in bipolar disorder. The diagnostic issues at the interface are particularly difficult because of the substantial symptom overlap. The treatment of co-existing conditions has clinically remained challenging. PMID:26629535

  1. Recent Direct Reaction Experimental Studies with Radioactive Tin Beams

    SciTech Connect

    Jones, K. L.; Ahn, S.; Allmond, J. M.; Ayres, A.; Bardayan, D. W.; Baugher, T.; Bazin, D.; Berryman, J. S.; Bey, A.; Bingham, C.; Cartegni, L.; Cerizza, G.; Chae, K. Y.; Cizewski, J. A.; Gade, A.; Galindo-Uribarri, A.; Garcia-Ruiz, R. F.; Grzywacz, R.; Howard, M. E.; Kozub, R. L.; Liang, J. F.; Manning, B.; Matoš, M.; McDaniel, S.; Miller, D.; Nesaraja, C. D.; O'Malley, P. D.; Padgett, S.; Padilla-Rodal, E.; Pain, S. D.; Pittman, S. T.; Radford, D. C.; Ratkiewicz, A.; Schmitt, K. T.; Shore, A.; Smith, M. S.; Stracener, D. W.; Stroberg, S. R.; Tostevin, J.; Varner, R. L.; Weisshaar, D.; Wimmer, K.; Winkler, R.

    2015-01-01

    Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z = 50 proton shell closure, as well as the neutron shell closures lying in the neutron-rich, N = 82, and neutron-deficient, N = 50, regions. Here, we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in Sn-131 from across the N = 82 shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient Sn-106,108Sn. In conclusion, In both cases, measurements of γ rays in coincidence with charged particles proved to be invaluable.

  2. Recent Direct Reaction Experimental Studies with Radioactive Tin Beams

    DOE PAGES

    Jones, K. L.; Ahn, S.; Allmond, J. M.; Ayres, A.; Bardayan, D. W.; Baugher, T.; Bazin, D.; Berryman, J. S.; Bey, A.; Bingham, C.; et al

    2015-01-01

    Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z = 50 proton shell closure, as well as the neutron shell closures lying in the neutron-rich, Nmore » = 82, and neutron-deficient, N = 50, regions. Here, we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in Sn-131 from across the N = 82 shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient Sn-106,108Sn. In conclusion, In both cases, measurements of γ rays in coincidence with charged particles proved to be invaluable.« less

  3. Vibrational lifetimes of hydrated phospholipids

    NASA Astrophysics Data System (ADS)

    Jadidi, Tayebeh; Anvari, Mehrnaz; Mashaghi, Alireza; Sahimi, Muhammad; Rahimi Tabar, M. Reza

    2013-04-01

    Large-scale ab initio molecular-dynamics simulations have been carried out to compute, at human-body temperature, the vibrational modes and lifetimes of pure and hydrated dipalmitoylphosphatidylcholine (DPPC) lipids. The projected atomic vibrations calculated from the spectral energy density are used to compute the vibrational modes and the lifetimes. All the normal modes of the pure and hydrated DPPC and their frequencies are identified. The computed lifetimes incorporate the full anharmonicity of the atomic interactions. The vibrational modes of the water molecules close to the head group of DPPC are active (possess large projected spectrum amplitudes) in the frequency range 0.5-55 THz, with a peak at 2.80 THz in the energy spectrum. The computed lifetimes for the high-frequency modes agree well with the recent data measured at room temperature where high-order phonon scattering is not negligible. The computed lifetimes of the low-frequency modes can be tested using the current experimental capabilities. Moreover, the approach may be applied to other lipids and biomolecules, in order to predict their vibrational dispersion relations, and to study the dynamics of vibrational energy transfer.

  4. Beam-transport study of an isocentric rotating ion gantry with minimum number of quadrupoles

    NASA Astrophysics Data System (ADS)

    Pavlovic, Márius; Griesmayer, Erich; Seemann, Rolf

    2005-06-01

    A beam-transport study of an isocentric gantry for ion therapy is presented. The gantry is designed with the number of quadrupoles down to the theoretical minimum, which is the feature published for the first time in this paper. This feature has been achieved without compromising the ion-optical functions of the beam-transport system that is capable of handling non-symmetric beams (beams with different emittances in vertical and horizontal plane), pencil-beam scanning, double-achromatic optics and beam-size control. Ion-optical properties of the beam-transport system are described, discussed and illustrated by computer simulations performed by the TRANSPORT-code.

  5. Experimental Studying of Dust Particles Charging by Electron Beam

    SciTech Connect

    Gavrikov, A. V.; Fortov, V. E.; Petrov, O. F.; Vorona, N. A.; Vasiliev, M. N.

    2008-09-07

    The studying of the dusty plasma properties under electron beam action are of great interest because it gives the unique opportunities for experimental investigation of strongly coupled systems as well as for developing the new dusty plasma technologies of creating the new composite materials. Highly charged dust particle generates electrostatic field that can accelerate positive ions to high power. It gives the unique possibilities of using these macroparticles (for deeply ions implantation, as catalysts for increasing rate of reactions with the high energy barrier, in the new ionic engines etc.). Presented work deals with the experimental investigation of dust particles charging under direct influence of electron beam. On the basis of experimental data the average velocities of dust particles were obtained and the charge of macroparticle was estimated.

  6. A Study of Effects of Tissue Inhomogeneity on HIFU Beam

    NASA Astrophysics Data System (ADS)

    Amin, Viren; Roberts, Ron; Long, Tao; Thompson, R. B.; Ryken, Timothy

    2006-05-01

    The potential of high-intensity focused ultrasound (HIFU) will not be realized unless the effects of overlaying tissues are understood in such a way that allows for estimation of HIFU dose distribution at a target tissue. We employ computational models to examine the impact of phase aberration on tissue ablation. Thompson and Roberts have recently studied the effects of phase aberration on ultrasound focusing in aerospace engine materials such as titanium alloy, and have developed a computational model to examine these effects. The ultrasound beam observed after transmission through the fused quartz (homogeneous) and that observed after transmission through the titanium (inhomogeneous) demonstrate the severe beam wavefield amplitude distortion introduced by the velocity inhomogeneity-induced phase aberration. We study applicability of this approach to model phase aberration in inhomogeneous tissues and its effect on HIFU dose distribution around the focus. It is hypothesized that the ill-effects of phase aberration accumulate during propagation through intervening tissue in which field intensities are substantially lower than that in the focal zone, and it is therefore appropriate to use a linear acoustic model to describe the transport of energy from the transducer to the volume targeted for ablation. We present initial results of the simulation and experiments of beam measurements under water without and with different tissue layers.

  7. Lifetime risk of ESRD.

    PubMed

    Turin, Tanvir Chowdhury; Tonelli, Marcello; Manns, Braden J; Ahmed, Sofia B; Ravani, Pietro; James, Matthew; Hemmelgarn, Brenda R

    2012-09-01

    Lifetime risk is the cumulative risk of experiencing an outcome between a disease-free index age and death. The lifetime risk of ESRD for a middle-aged individual is a relevant and easy to communicate measure of disease burden. We estimated lifetime risk of ESRD in a cohort of 2,895,521 adults without ESRD from 1997 to 2008. To estimate lifetime risk of ESRD by level of baseline kidney function, we analyzed a cohort of participants who had a serum creatinine measurement. We also estimated the sex- and index age-specific lifetime risk of incident ESRD and accounted for the competing risk of death. Among those individuals without ESRD at age 40 years, the lifetime risk of ESRD was 2.66% for men and 1.76% for women. The risk was higher in persons with reduced kidney function: for eGFR=44-59 ml/min per 1.73 m(2), the lifetime risk of ESRD was 7.51% for men and 3.21% for women, whereas men and women with relatively preserved kidney function (eGFR=60-89 ml/min per 1.73 m(2)) had lifetime risks of ESRD of 1.01% and 0.63%, respectively. The lifetime risk of ESRD was consistently higher for men at all ages and eGFR strata compared with women. In conclusion, approximately 1 in 40 men and 1 in 60 women of middle age will develop ESRD during their lifetimes (living into their 90s). These population-based estimates may assist individuals who make decisions regarding public health policy.

  8. Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation

    SciTech Connect

    Han, B. X.; Welton, R. F.; Murray, S. N. Jr.; Pennisi, T. R.; Santana, M.; Stockli, M. P.; Kalvas, T.; Tarvainen, O.

    2012-02-15

    The H{sup -} injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with {approx}38 mA beam current in the linac at 60 Hz with a pulse length of up to {approx}1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.

  9. Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation

    SciTech Connect

    Kalvas, T.; Welton, Robert F; Pennisi, Terry R

    2012-01-01

    The H{sup -} injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with {approx}38 mA beam current in the linac at 60 Hz with a pulse length of up to {approx}1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.

  10. Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation.

    PubMed

    Han, B X; Kalvas, T; Tarvainen, O; Welton, R F; Murray, S N; Pennisi, T R; Santana, M; Stockli, M P

    2012-02-01

    The H(-) injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with ∼38 mA beam current in the linac at 60 Hz with a pulse length of up to ∼1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.

  11. Index grating lifetime in photorefractive GaAs

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Partovi, Afshin

    1988-01-01

    The index grating lifetime in liquid encapsulated Czochralski-grown undoped semi-insulating GaAs was measured using a beam coupling technique. The largest lifetime measure was about 8 s under a read beam intensity of 0.7 mW/sq cm with the grating periodicity being 0.63 microns. The measured value decreases to milliseconds as the read beam intensity and the grating periodicity increase to about 10 mW/sq cm and 4 microns, respectively. This range of grating lifetime in this material is adequate for its use in real-time spatial light modulators, reconfigurable beam steering devices, and dynamic memory elements, for optical computing. In addition, the results suggest that the lifetime is sensitive to residual imperfections in the crystal.

  12. Study of bicontinuous phase in (TTAB+pentanol)/water/n-octane reverse micellar system using positron lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Chandramani Singh, K.; Yadav, R.; Khani, P. H.

    2013-06-01

    A phase diagram of (TTAB+pentanol)/water/n-octane has been mapped by using optical method. It exhibits a reverse micellar (L2) phase extending over a wide range of concentrations of the constituents. To investigate the fine structure of the L2 phase, a series of (TTAB+pentanol)/n-octane ternary mixtures having initial concentrations of (TTAB+pentanol) (1:1) in n-octane as 35%, 50% and 65% by weight were prepared. In each of these mixtures, positron lifetime measurements were performed as a function of the concentration of water, using a standard lifetime spectrometer. At water concentrations of 11.8%, 8.5% and 8.4% by weight respectively for the above systems, the o-Ps pick-off lifetime τ3 shows an oscillatory behaviour while I3 representing the Ps formation exhibits an abrupt change. These changes in the positron annihilation parameters have been explained on the basis of onset of bicontinuity in the microemulsion phase. The positron annihilation technique thus suggests the existence of droplet-like and bicontinuous structures in the L2 phase which is otherwise considered optically to be a single phase as the system remains clear and isotropic throughout this phase. Supporting evidence has been provided by the electrical conductivity measurements performed in these systems. These results are presented in this paper.

  13. Cryogenic Lifetime Studies of 130 nm and 65 nm CMOS Technologies for High-Energy Physics Experiments

    SciTech Connect

    Hoff, James R.; Deptuch, G. W.; Wu, Guoying; Gui, Ping

    2015-06-04

    The Long Baseline Neutrino Facility intends to use unprecedented volumes of liquid argon to fill a time projection chamber in an underground facility. Research is under way to place the electronics inside the cryostat. For reasons of efficiency and economics, the lifetimes of these circuits must be well in excess of 20 years. The principle mechanism for lifetime degradation of MOSFET devices and circuits operating at cryogenic temperatures is hot carrier degradation. Choosing a process technology that is, as much as possible, immune to such degradation and developing design techniques to avoid exposure to such damage are the goals. This, then, requires careful investigation and a basic understanding of the mechanisms that underlie hot carrier degradation and the secondary effects they cause in circuits. In this work, commercially available 130 nm and 65 nm nMOS transistors operating at cryogenic temperatures are investigated. Our results show that both technologies achieve the lifetimes required by the experiment. Minimal design changes are necessary in the case of the 130 nm process and no changes whatsoever are necessary for the 65 nm process.

  14. Feasibility study of beam-beam compensation in the Tevatron with wires

    SciTech Connect

    Sen, Tanaji; Erdelyi, Bela; /Northern Illinois U.

    2005-05-01

    We explore the possibility of compensating long-range beam-beam interactions in the Tevatron by current carrying wires. Compensation strategies depend on whether the compensation is done close to the interaction or nonlocally, on the aspect ratio of the strong beam and on other details. Strategies for each case have been developed and applied to the Tevatron. We discuss the results of these strategies at injection and collision energy.

  15. Beam Line Design and Beam Physics Study of Energy Recovery Linac Free Electron Laser at Peking University

    SciTech Connect

    Wang, Guimei

    2011-12-31

    Energy recovering linac (ERL) offers an attractive alternative for generating intense beams of charged particles by approaching the operational efficiency of a storage ring while maintaining the superior beam quality typical of a linear accelerator. In ERLs, the decelerated beam cancels the beam loading effects of the accelerated beam with high repetition rate. Therefore, ERLs can, in principle, accelerate very high average currents with only modest amounts of RF power. So the efficiency of RF power to beam is much higher. Furthermore, the energy of beam to dump is lower, so it will reduce dump radiation. With the successful experiments in large maximum-to-injection energy ratio up to 51:1 and high power FEL up to 14kW, the use of ERL, especially combining with superconducting RF technology, provides a potentially powerful new paradigm for generation of the charged particle beams used in MW FEL, synchrotron radiation sources, high-energy electron cooling devices and so on. The 3+1/2 DC-SC photo injector and two 9cell TESLA superconducting cavity for IR SASE FEL in PKU provides a good platform to achieve high average FEL with Energy Recovery. The work of this thesis is on Beam line design and Beam dynamics study of Energy Recovery Linac Free Electron Laser for Peking University. It is the upgrade of PKU facility, which is under construction. With ERL, this facility can work in CW mode, so it can operate high average beam current without RF power constraint in main linac and generate high average FEL power. Moreover, it provides a test facility to study the key technology in ERL. System parameters are optimized for PKU ERL-FEL. The oscillation FEL output power is studied with different bunch charge, transverse emittance, bunch length and energy spread. The theory of optimal RF power and Q{sub ext} with ERL and without ERL is analyzed and applied to PKU injector and linac including microphonic effect. pace charge effect in the injector and merger is studied for beam

  16. Radiobiological study by using laser-driven proton beams

    SciTech Connect

    Yogo, A.; Nishikino, M.; Mori, M.; Ogura, K.; Sagisaka, A.; Orimo, S.; Nishiuchi, M.; Pirozhkov, A. S.; Ikegami, M.; Tampo, M.; Sakaki, H.; Suzuki, M.; Daito, I.; Kiriyama, H.; Okada, H.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Nakai, Y.; Kawachi, T.

    2009-07-25

    Particle acceleration driven by high-intensity laser systems is widely attracting interest as a potential alternative to conventional ion acceleration, including ion accelerator applications to tumor therapy. Recent works have shown that a high intensity laser pulse can produce single proton bunches of a high current and a short pulse duration. This unique feature of laser-ion acceleration can lead to progress in the development of novel ion sources. However, there has been no experimental study of the biological effects of laser-driven ion beams. We describe in this report the first demonstrated irradiation effect of laser-accelerated protons on human lung cancer cells. In-vitro A549 cells are irradiated with a proton dose of 20 Gy, resulting in a distinct formation of gamma-H2AX foci as an indicator of DNA double-strand breaks. This is a pioneering result that points to future investigations of the radiobiological effects of laser-driven ion beams. The laser-driven ion beam is apotential excitation source for time-resolved determination of hydroxyl (OH) radical yield, which will explore relationship between the fundamental chemical reactions of radiation effects and consequent biological processes.

  17. Radiobiological study by using laser-driven proton beams

    NASA Astrophysics Data System (ADS)

    Yogo, A.; Sato, K.; Nishikino, M.; Mori, M.; Teshima, T.; Numasaki, H.; Murakami, M.; Demizu, Y.; Akagi, S.; Nagayama, S.; Ogura, K.; Sagisaka, A.; Orimo, S.; Nishiuchi, M.; Pirozhkov, A. S.; Ikegami, M.; Tampo, M.; Sakaki, H.; Suzuki, M.; Daito, I.; Oishi, Y.; Sugiyama, H.; Kiriyama, H.; Okada, H.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Nakai, Y.; Tanoue, M.; Sugiyama, H.; Sasao, H.; Wakai, D.; Kawachi, T.; Nishimura, H.; Bolton, P. R.; Daido, H.

    2009-07-01

    Particle acceleration driven by high-intensity laser systems is widely attracting interest as a potential alternative to conventional ion acceleration, including ion accelerator applications to tumor therapy. Recent works have shown that a high intensity laser pulse can produce single proton bunches of a high current and a short pulse duration. This unique feature of laser-ion acceleration can lead to progress in the development of novel ion sources. However, there has been no experimental study of the biological effects of laser-driven ion beams. We describe in this report the first demonstrated irradiation effect of laser-accelerated protons on human lung cancer cells. In-vitro A549 cells are irradiated with a proton dose of 20 Gy, resulting in a distinct formation of γ-H2AX foci as an indicator of DNA double-strand breaks. This is a pioneering result that points to future investigations of the radiobiological effects of laser-driven ion beams. The laser-driven ion beam is apotential excitation source for time-resolved determination of hydroxyl (OH) radical yield, which will explore relationship between the fundamental chemical reactions of radiation effects and consequent biological processes.

  18. Lifetime and g-factor measurements of excited states using Coulomb excitation and alpha transfer reactions

    NASA Astrophysics Data System (ADS)

    Guevara, Z. E.; Torres, D. A.

    2016-07-01

    In this contribution the challenges in the use of a setup to simultaneously measure lifetimes and g-factor values will be presented. The simultaneous use of the transient field technique and the Doppler Shift Attenuation Method, to measure magnetic moments and lifetimes respectively, allows to obtain a complete characterization of the currents of nucleons and the deformation in excited states close to the ground state. The technique is at the moment limited to Coulomb excitation and alpha-transfer reactions, what opens an interesting perspective to consider this type of experiments with radioactive beams. The use of deep-inelastic and fusion-evaporation reactions will be discussed. An example of a setup that makes use of a beam of 106Cd to study excited states of 110Sn and the beam nuclei itself will be presented.

  19. Design study of longitudinal dynamics of the drive beam in 1 TeV relativistic klystron two-beam accelerator

    SciTech Connect

    Li, H.; Yu, S.S.; Sessler, A.M.

    1994-10-01

    In this paper the authors present a design study on the longitudinal dynamics of a relativistic klystron two-beam accelerator (RK-TBA) scheme which has been proposed as a power source candidate for a 1 TeV next linear collider (NLC). They address the issue of maintaining stable power output at desired level for a 300-m long TBA with 150 extraction cavities and present their simulation results to demonstrate that it can be achieved by inductively detuning the extraction cavities to counter the space charge debunching effect on the drive beam. They then carry out simulation study to show that the beam bunches desired by the RK-TBA can be efficiently obtained by first chopping an initially uniform beam of low energy into a train of beam bunches with modest longitudinal dimension and then using the {open_quotes}adiabatic capture{close_quotes} scheme to bunch and accelerate these beam bunches into tight bunches at the operating energy of the drive beam. The authors have also examined the {open_quotes}after burner{close_quotes} scheme which is implemented in their RK-TBA design for efficiency enhancement.

  20. Study of beam optics and beam halo by integrated modeling of negative ion beams from plasma meniscus formation to beam acceleration

    SciTech Connect

    Miyamoto, K.; Okuda, S.; Hatayama, A.; Hanada, M.; Kojima, A.

    2013-01-14

    To understand the physical mechanism of the beam halo formation in negative ion beams, a two-dimensional particle-in-cell code for simulating the trajectories of negative ions created via surface production has been developed. The simulation code reproduces a beam halo observed in an actual negative ion beam. The negative ions extracted from the periphery of the plasma meniscus (an electro-static lens in a source plasma) are over-focused in the extractor due to large curvature of the meniscus.

  1. Fluorescence lifetime imaging of skin cancer

    NASA Astrophysics Data System (ADS)

    Patalay, Rakesh; Talbot, Clifford; Munro, Ian; Breunig, Hans Georg; König, Karsten; Alexandrov, Yuri; Warren, Sean; Neil, Mark A. A.; French, Paul M. W.; Chu, Anthony; Stamp, Gordon W.; Dunsby, Chris

    2011-03-01

    Fluorescence intensity imaging and fluorescence lifetime imaging microscopy (FLIM) using two photon microscopy (TPM) have been used to study tissue autofluorescence in ex vivo skin cancer samples. A commercially available system (DermaInspect®) was modified to collect fluorescence intensity and lifetimes in two spectral channels using time correlated single photon counting and depth-resolved steady state measurements of the fluorescence emission spectrum. Uniquely, image segmentation has been used to allow fluorescence lifetimes to be calculated for each cell. An analysis of lifetime values obtained from a range of pigmented and non-pigmented lesions will be presented.

  2. Recent progress on beam stability study in the PSR

    NASA Astrophysics Data System (ADS)

    Wang, Tai-Sen F.; Channell, Paul J.; Cooper, Richard K.; Fitzgerald, Daniel H.; Hardek, Tom; Hutson, Richard; Jason, Andrew J.; Macek, Robert J.; Plum, Michael A.; Wilkinson, Carol

    A fast transverse instability has been observed in the Los Alamos Proton Storage Ring (PSR) when the injected beam intensity reaches more than 2 (times) 10(exp 13) protons per pulse. Understanding the cause and control of this instability has taken on new importance as the neutron-scattering community considers the next generation of accelerator-driven spallation-neutron sources, which call for peak-proton intensities of 10(exp 14) per pulse or higher. Previous observations and theoretical studies indicate that the instability in the PSR is most likely driven by electrons trapped within the proton beam. Recent studies using an experimental electron-clearing system and voltage-biased pinger-electrodes for electron clearing and collection support this hypothesis. Experiments have also been performed to study the instability threshold when varying the electron production rate. Theoretical studies include a computer simulation of a simplified model for the e -- p instability and the investigation of possible electron confinement in the ring-element magnetic fields. This paper reports some recent results from these studies.

  3. Recent progress on beam stability study in the PSR

    SciTech Connect

    Wang, T.; Channell, P.; Cooper, R.

    1995-05-01

    A fast transverse instability has been observed in the Los Alamos Proton Storage Ring (PSR) when the injected beam intensity reaches more than 2 {times} 10{sup 13} protons per pulse. Understanding the cause and control of this instability has taken on new importance as the neutron-scattering community considers the next generation of accelerator-driven spallation-neutron sources, which call for peak-proton intensities of 10{sup 14} per pulse or higher. Previous observations and theoretical studies indicate that the instability in the PSR is most likely driven by electrons trapped within the proton beam. Recent studies using an experimental electron-clearing system and voltage-biased pinger-electrodes for electron clearing and collection support this hypothesis. Experiments have also been performed to study the instability threshold when varying the electron production rate. Theoretical studies include a computer simulation of a simplified model for the e -- p instability and the investigation of possible electron confinement in the ring-element magnetic fields. This paper reports some recent results from these studies.

  4. Measurement of the Omega0(c) lifetime

    SciTech Connect

    Iori, M.; Ayan, A.S.; Akgun, U.; Alkhazov, G.; Amaro-Reyes, J.; Atamantchouk, A.G.; Balatz, M.Y.; Blanco-Covarrubias, A.; Bondar, N.F.; Cooper, P.S.; Dauwe, L.J.; /Ball State U. /Bogazici U. /Carnegie Mellon U. /Rio de Janeiro, CBPF /Fermilab /Serpukhov, IHEP /Beijing, Inst. High Energy Phys. /Moscow, ITEP /Heidelberg, Max Planck Inst. /Moscow State U. /St. Petersburg, INP

    2007-01-01

    The authors report a precise measurement of the {Omega}{sub c}{sup 0} lifetime. The data were taken by the SELEX (E781) experiment using 600 GeV/c {Sigma}{sup -}, {pi}{sup -} and p beams. The measurement has been made using 83 {+-} 19 reconstructed {Omega}{sub c}{sup 0} in the {Omega}{sup -} {pi}{sup -}{pi}{sup +}{pi}{sup +} and {Omega}{sup -} {pi}{sup +} decay modes. The lifetime of the {Omega}{sub c}{sup 0} is measured to be 65 {+-} 13(stat) {+-} 9(sys) fs.

  5. Positron annihilation lifetime studies of changes in free volume on some biorelevant nitrogen heterocyclic compounds and their S-glycosylation.

    PubMed

    Mahmoud, K R; Khodair, A I; Shaban, S Y

    2015-11-01

    A series of N-heterocyclic compounds was investigated by positron annihilation lifetime spectroscopy as well as Doppler broadening of annihilation radiation (DBAR) at room temperature. The results showed that the formation probability and life time of ortho-positronium in this series are structure and electron-donation character dependent, and can give more information about the structure. The DBAR provides direct information about the change of core and valance electrons as well as the number of defect types present in these compounds. PMID:26272166

  6. Study of the effect of annealing on defects in Fe Mn Si Cr Ni C alloy by slow positron beam

    NASA Astrophysics Data System (ADS)

    Mostafa, Khaled. M.; De Baerdemaeker, J.; Van Caenegem, N.; Segers, D.; Houbaert, Y.

    2008-10-01

    FeMnSi shape memory alloys (SMAs) have received much attention as one-way SMAs due to their cost-effectiveness. Variable-energy (0-30 keV) positron beam studies have been carried out on a Fe-Mn-Si-Cr-Ni-C alloy with different degrees of deformation. Doppler broadening profiles of the positron annihilation as a function of incident positron energy were shown to be quite sensitive to defects introduced by deformation. The variation of the nature and the concentration of defects are studied as a function of isochronal annealing temperature. These results are correlated with the data measured with the positron annihilation lifetime spectroscopy (PALS). The positron annihilation results are compared to XRD and optical microscopy (OM).

  7. Design study of low-energy beam transport for multi-charge beams at RAON

    NASA Astrophysics Data System (ADS)

    Bahng, Jungbae; Qiang, Ji; Kim, Eun-San

    2015-12-01

    The Rare isotope Accelerator Of Newness (RAON) at the Rare Isotope Science Project (RISP) is being designed to simultaneously accelerate beams with multiple charge states. It includes a driver superconducting (SC) linac for producing 200 MeV/u and 400 kW continuous wave (CW) heavy ion beams from protons to uranium. The RAON consists of a few electron cyclotron resonance ion sources, a low-energy beam transport (LEBT) system, a CW 81.25 MHz, 500 keV/u radio frequency quadrupole (RFQ) accelerator, a medium-energy beam transport system, the SC linac, and a charge-stripper system. The LEBT system for the RISP accelerator facility consists of a high-voltage platform, two 90° dipoles, a multi-harmonic buncher (MHB), solenoids, electrostatic quadrupoles, a velocity equalizer, and a diagnostic system. The ECR ion sources are located on a high-voltage platform to reach an initial beam energy of 10 keV/u. After extraction, the ion beam is transported through the LEBT system to the RFQ accelerator. The generated charge states are selected by an achromatic bending system and then bunched by the MHB in the LEBT system. The MHB is used to achieve a small longitudinal emittance in the RFQ by generating a sawtooth wave with three harmonics. In this paper, we present the results and issues of the beam dynamics of the LEBT system.

  8. Nuclear structure studies with gamma-ray beams

    DOE PAGES

    Tonchev, Anton; Bhatia, Chitra; Kelley, John; Raut, Rajarshi; Rusev, Gencho; Tornow, Werner; Tsoneva, Nadia

    2015-05-28

    In stable and weakly bound neutron-rich nuclei, a resonance-like concentration of dipole states has been observed for excitation energies below the neutron-separation energy. This clustering of strong dipole states has been named the Pygmy Dipole Resonance (PDR) in contrast to the Giant Dipole Resonance (GDR) that dominates the E1 response. Understanding the PDR is presently of great interest in nuclear structure and nuclear astrophysics. High-sensitivity studies of E1 and M1 transitions in closed-shell nuclei using monoenergetic and 100% linearly-polarized photon beams are presented.

  9. Dynamic fluorescence lifetime imaging based on acousto-optic deflectors

    NASA Astrophysics Data System (ADS)

    Yan, Wei; Peng, Xiao; Qi, Jing; Gao, Jian; Fan, Shunping; Wang, Qi; Qu, Junle; Niu, Hanben

    2014-11-01

    We report a dynamic fluorescence lifetime imaging (D-FLIM) system that is based on a pair of acousto-optic deflectors for the random regions of interest (ROI) study in the sample. The two-dimensional acousto-optic deflector devices are used to rapidly scan the femtosecond excitation laser beam across the sample, providing specific random access to the ROI. Our experimental results using standard fluorescent dyes in live cancer cells demonstrate that the D-FLIM system can dynamically monitor the changing process of the microenvironment in the ROI in live biological samples.

  10. Vacancy-type defects induced by grinding of Si wafers studied by monoenergetic positron beams

    SciTech Connect

    Uedono, Akira; Yoshihara, Nakaaki; Mizushima, Yoriko; Kim, Youngsuk; Nakamura, Tomoji; Ohba, Takayuki; Oshima, Nagayasu; Suzuki, Ryoichi

    2014-10-07

    Vacancy-type defects introduced by the grinding of Czochralski-grown Si wafers were studied using monoenergetic positron beams. Measurements of Doppler broadening spectra of the annihilation radiation and the lifetime spectra of positrons showed that vacancy-type defects were introduced in the surface region (<98 nm), and the major defect species were identified as (i) relatively small vacancies incorporated in dislocations and (ii) large vacancy clusters. Annealing experiments showed that the defect concentration decreased with increasing annealing temperature in the range between 100 and 500°C. After 600–700°C annealing, the defect-rich region expanded up to about 170 nm, which was attributed to rearrangements of dislocation networks, and a resultant emission of point defects toward the inside of the sample. Above 800°C, the stability limit of those vacancies was reached and they started to disappear. After the vacancies were annealed out (900°C), oxygen-related defects were the major point defects and they were located at <25 nm.

  11. The costs of inequality: whole-population modelling study of lifetime inpatient hospital costs in the English National Health Service by level of neighbourhood deprivation

    PubMed Central

    Doran, Tim; Cookson, Richard

    2016-01-01

    Background There are substantial socioeconomic inequalities in both life expectancy and healthcare use in England. In this study, we describe how these two sets of inequalities interact by estimating the social gradient in hospital costs across the life course. Methods Hospital episode statistics, population and index of multiple deprivation data were combined at lower-layer super output area level to estimate inpatient hospital costs for 2011/2012 by age, sex and deprivation quintile. Survival curves were estimated for each of the deprivation groups and used to estimate expected annual costs and cumulative lifetime costs. Results A steep social gradient was observed in overall inpatient hospital admissions, with rates ranging from 31 298/100 000 population in the most affluent fifth of areas to 43 385 in the most deprived fifth. This gradient was steeper for emergency than for elective admissions. The total cost associated with this inequality in 2011/2012 was £4.8 billion. A social gradient was also observed in the modelled lifetime costs where the lower life expectancy was not sufficient to outweigh the higher average costs in the more deprived populations. Lifetime costs for women were 14% greater than for men, due to higher costs in the reproductive years and greater life expectancy. Conclusions Socioeconomic inequalities result in increased morbidity and decreased life expectancy. Interventions to reduce inequality and improve health in more deprived neighbourhoods have the potential to save money for health systems not only within years but across peoples’ entire lifetimes, despite increased costs due to longer life expectancies. PMID:27189975

  12. Lifetime cigarette smoking is associated with abdominal obesity in a community-based sample of Japanese men: The Shiga Epidemiological Study of Subclinical Atherosclerosis (SESSA).

    PubMed

    Fujiyoshi, Akira; Miura, Katsuyuki; Kadowaki, Sayaka; Azuma, Koichiro; Tanaka, Sachiko; Hisamatsu, Takashi; Arima, Hisatomi; Kadota, Aya; Miyagawa, Naoko; Takashima, Naoyuki; Ohkubo, Takayoshi; Saitoh, Yoshino; Torii, Sayuki; Miyazawa, Itsuko; Maegawa, Hiroshi; Murata, Kiyoshi; Ueshima, Hirotsugu

    2016-12-01

    Studies from Western countries suggest that smokers tend to display greater abdominal obesity than non-smokers, despite showing lower weight. Whether this holds true in a leaner population requires clarification. Using indices of abdominal obesity including visceral adipose tissue, we examined whether lifetime cigarette smoking is associated with unfavorable fat distribution among Japanese men. From 2006 to 2008, we conducted a cross-sectional investigation of a community-based sample of Japanese men at 40-64 years old, free of cardiovascular diseases and cancer. Areas of abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were calculated using computed tomography. We divided participants into four groups: never-smokers; and tertiles of pack-years of smoking among ever-smokers. Using multivariable linear regression, we calculated adjusted means of obesity indices (VAT, SAT, VAT-SAT ratio [VSR], and waist-hip ratio [WHR]) for each group, and mean differences between consecutive groups. We analyzed 513 men (median age, 58.2 years; current smokers, 40.1%). Two-thirds showed body mass index (BMI) < 25 kg/m(2) (median, 23.5 kg/m(2)). Overall, greater lifetime smoking group was associated with greater WHR and VSR. On average, one higher smoking group was associated with 0.005 higher WHR (95% CI, 0.001-0.008; P = 0.005) and 0.041 greater VSR (95% CI, 0.009-0.073; P = 0.012) after adjustment for potential confounders, including BMI. In this sample of relatively lean Japanese men, greater lifetime smoking was associated with a metabolically more adverse fat distribution. Although smoking is commonly associated with lower BMI, minimizing the amount of lifetime smoking should be advocated. PMID:27413686

  13. Beam storage studies in the Fermilab main ring

    SciTech Connect

    MacLachlan, J.A.

    1982-05-06

    Bunched beams of 100 and 150 GeV have been stored in the Fermilab Main Ring for periods of up to one hour. The observations of beam current and beam profiles are analyzed for the effects of gas scattering, chromaticity and non-linear magnetic field.

  14. Beam-storage studies in the Fermilab main ring

    SciTech Connect

    MacLachlan, J.A.

    1982-05-06

    Bunched beams of 100 and 150 GeV have been stored in the Fermilab Main Ring for periods of up to one hour. The observations of beam current and beam profiles are analyzed for the effects of gas scattering, chromaticity and non-linear magnetic field.

  15. (Anti)hypertriton lifetime puzzle

    NASA Astrophysics Data System (ADS)

    Ma, Yu-Gang

    2016-05-01

    Most calculations on the lifetime of (anti)hypertriton gave a similar lifetime which is close to the lifetime of free Λ decays. However, recent measurements on (anti)hypertriton lifetime demonstrate a much short lifetime. All results for (anti)hypertriton lifetime by two-body decay channel of 3He + π for Au+Au collision at RHIC, Pb+Pb collision at LHC and Li + C collisions at GSI show a significant short lifetime in comparison with lifetime of free Λ decays. However, theoretical interpretation remains puzzle.

  16. Nuclear Structure Studies with Stable and Radioactive Beams: The SPES radioactive ion beam project

    NASA Astrophysics Data System (ADS)

    de Angelis, G.; SPES Collaboration; Prete, G.; Andrighetto, A.; Manzolaro, M.; Corradetti, S.; Scarpa, D.; Rossignoli, M.; Monetti, A.; Lollo, M.; Calderolla, M.; Vasquez, J.; Zafiropoulos, D.; Sarchiapone, L.; Benini, D.; Favaron, P.; Rigato, M.; Pegoraro, R.; Maniero, D.; Calabretta, L.; Comunian, M.; Maggiore, M.; Lombardi, A.; Piazza, L.; Porcellato, A. M.; Roncolato, C.; Bisoffi, G.; Pisent, A.; Galatà, A.; Giacchini, M.; Bassato, G.; Canella, S.; Gramegna, F.; Valiente, J.; Bermudez, J.; Mastinu, P. F.; Esposito, J.; Wyss, J.; Russo, A.; Zanella, S.

    2015-04-01

    A new Radioactive Ion Beam (RIB) facility (SPES) is presently under construction at the Legnaro National Laboratories of INFN. The SPES facility is based on the ISOL method using an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is provided by a high current Cyclotron accelerator with energy of 35-70 MeV and a beam current of 0.2-0.5 mA. Neutron-rich radioactive ions are produced by proton induced fission on an Uranium target at an expected fission rate of the order of 1013 fissions per second. After ionization and selection the exotic isotopes are re-accelerated by the ALPI superconducting LINAC at energies of 10A MeV for masses in the region A=130 amu. The expected secondary beam rates are of the order of 107 - 109 pps. Aim of the SPES facility is to deliver high intensity radioactive ion beams of neutron rich nuclei for nuclear physics research as well as to be an interdisciplinary research centre for radio-isotopes production for medicine and for neutron beams.

  17. Study and design of beam expander with wide aperture

    NASA Astrophysics Data System (ADS)

    Guo, Ming; Jin, Guangyong; Cai, Jixing; Zhang, Wei; Wei, Zhi

    2014-12-01

    In order to improve the capacity of beam collimation for laser beam expander, it is necessary to design a more reasonable and feasible structure of beam expander system. Laser beam expander is used to compress the laser divergence angle, in order to reduce the energy losing in long distance scanning acquisition system. This paper introduces the working principle and design idea of the laser beam expander, the collimating multiplying power focal length and the collimated magnification formula of expander main, secondary mirror. According to the third-order aberration theory, Considering the spherical aberration, sine difference and divergence angle, the reasonable analysis of optical path, ZEMAX optical design software was used to design large-diameter laser beam expander and analysis and optimize, And given the actual design data and results. Display the maximum optical path difference is +/-0.01λ of the main light ray and each light ray. To combination the rear- group objective lens of Galileo and Kepler beam expander, a large-diameter(1.475m) laser beam expander was designed with 0.2m in the diameter, 1/2m in the relative caliber. In the objective lens System, a high-order aspherical was used to the aberration of extra-axial point. we can see that the image quality is close to the diffraction limit from the curves of wavefront. In addition to improve image quality effectively, the system has the characteristics of simple structure, less costly and less design difficulty to compare with the other beam expanding system. And make the output beam's divergence angle smaller, energy density higher, and the beam quality has been greatly improved. The results show that the beam expander is fully meet the design requirements, the use effect is good. Design and research of laser beam expanding system not only improves the quality of the laser beam in the laser system, but also enlarge the application field of laser technology in photoelectric system.

  18. Per-fluorinated sulfonic acid/PTFE copolymer studied by positron annihilation lifetime and gas permeation techniques

    NASA Astrophysics Data System (ADS)

    Mohamed, Hamdy F. M.; Abdel-Hady, E. E.; Ohira, A.

    2015-06-01

    The mechanism of gas permeation in per-fluorinated sulfonic acid/PTFE copolymer Fumapem® membranes for polymer electrolyte fuel cells has been investigated from the viewpoint of free volume. Three different samples, Fumapem® F-950, F-1050 and F-14100 membranes with ion exchange capacity (IEC) = 1.05, 0.95 and 0.71 meq/g, respectively were used after drying. Free volume was quantified using the positron annihilation lifetime (PAL) technique and gas permeabilities were measured for O2 and H2 as function of temperature. Good linear correlation between the logarithm of the permeabilities at different temperatures and reciprocal free volume indicate that gas permeation in dry Fumapem® is governed by the free volume. Nevertheless permeabilities are much smaller than the corresponding flexible chain polymer with a similar free volume size due to stiff chains of the perfluoroethylene backbone.

  19. Lifetime cost effectiveness of different brands of prosthesis used for total hip arthroplasty: a study using the NJR dataset.

    PubMed

    Pennington, M W; Grieve, R; van der Meulen, J H

    2015-06-01

    There is little evidence on the cost effectiveness of different brands of hip prostheses. We compared lifetime cost effectiveness of frequently used brands within types of prosthesis including cemented (Exeter V40 Contemporary, Exeter V40 Duration and Exeter V40 Elite Plus Ogee), cementless (Corail Pinnacle, Accolade Trident, and Taperloc Exceed) and hybrid (Exeter V40 Trilogy, Exeter V40 Trident, and CPT Trilogy). We used data from three linked English national databases to estimate the lifetime risk of revision, quality-adjusted life years (QALYs) and cost. For women with osteoarthritis aged 70 years, the Exeter V40 Elite Plus Ogee had the lowest risk of revision (5.9% revision risk, 9.0 QALYs) and the CPT Trilogy had the highest QALYs (10.9% revision risk, 9.3 QALYs). Compared with the Corail Pinnacle (9.3% revision risk, 9.22 QALYs), the most commonly used brand, and assuming a willingness-to-pay of £20,000 per QALY gain, the CPT Trilogy is most cost effective, with an incremental net monetary benefit of £876. Differences in cost effectiveness between the hybrid CPT Trilogy and Exeter V40 Trident and the cementless Corail Pinnacle and Taperloc Exceed were small, and a cautious interpretation is required, given the limitations of the available information. However, it is unlikely that cemented brands are among the most cost effective. Similar patterns of results were observed for men and other ages. The gain in quality of life after total hip arthroplasty, rather than the risk of revision, was the main driver of cost effectiveness. Cite this article: Bone Joint J 2015;97-B:762-70. PMID:26033055

  20. Study of Synchrotron Radiation for the Electron Beam Polarimeter for the MEIC

    SciTech Connect

    Sullivan, M.

    2015-08-06

    This is a look at the synchrotron radiation coming from the chicane in the electron beam line for the MEIC design. The power density on the beam pipe as well as transmission through the beam pipe is studied. The optics design is version 12.

  1. Studies of Limits on Uncontrolled Heavy Ion Beam Losses for Allowing Hands-On Maintenance

    SciTech Connect

    Reginald M. Ronningen; Igor Remec

    2010-09-11

    Dose rates from accelerator components activated by 1 W/m beam losses are obtained semiempirically for a 1 GeV proton beam and by use of Monte Carlo transport codes for the proton beam and for 777 MeV/u 3He, 500 MeV/u 48Ca, 86Kr, 136Xe, and 400 MeV/u 238U ions. The dose rate obtained by the semi-empirical method, 0.99 mSv/h (99 mrem/h) at 30 cm, 4 h after 100 d irradiation by a 1-GeV proton beam, is consistent with studies at several accelerator facilities and with adopted hands-on maintenance dose rate limits. Monte Carlo simulations verify this result for protons and extend studies to heavy ion beam losses in drift-tube linac and superconducting linac accelerating structures. The studies indicate that the 1 W/m limit imposed on uncontrolled beam losses for high-energy proton beams might be relaxed for heavy ion beams. These studies further suggest that using the ratio of neutrons produced by a heavy ion beam to neutrons produced by a proton beam along with the dose rate from the proton beam (for thin-target scenarios) should allow an estimate of the dose rates expected from heavy ion beam losses.

  2. Numerical Study of Collective Effects for Muon Beams

    SciTech Connect

    Huang, Dazhang; Kaplan, Daniel M.; Roberts, Thomas J.; Ng, King Y.; /Fermilab

    2009-05-01

    The study of Muon beam optics is crucial for future Neutrino Factory and Muon Collider facilities. At present, the GEANT4-based simulation tools for Muon beam tracking such as G4beamline and G4MICE only do single particle tracking without collective effects taken into account. However, it is known that collective interaction such as space charge and wakefields for muons (in matter or vacuum) are not ignorable. As the first step, space charge computation is implemented into muon tracking. The basic algorithm is particle-to-particle interaction through retarded electro-magnetic field. The momentum impulse due to collective effects is applied to every particle at each collective step, and the G4beamline main code is used for tracking. Comparisons to LANL Parmela are illustrated and analyzed. Optimizations of the algorithm are also underway to gain less computing time and more accuracy. Moreover, the idea of enhancing ionization cooling efficiency by utilizing the collective effect due to the polarized charges in matter appears to be possible, and preliminary estimates have been made.

  3. Simulation study of interactions of Space Shuttle-generated electron beams with ambient plasmas

    NASA Technical Reports Server (NTRS)

    Lin, Chin S.

    1992-01-01

    This report summarizes results obtained through the support of NASA Grant NAGW-1936. The objective of this report is to conduct large scale simulations of electron beams injected into space. The topics covered include the following: (1) simulation of radial expansion of an injected electron beam; (2) simulations of the active injections of electron beams; (3) parameter study of electron beam injection into an ionospheric plasma; and (4) magnetosheath-ionospheric plasma interactions in the cusp.

  4. Laboratory studies of the charge neutralization of a rocket payload during electron beam emission

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Whalen, B. A.; Harris, F. R.; Mcnamara, A. G.; Konradi, A.

    1980-01-01

    The charge neutralization of an electrically-isolated rocket payload emitting an energetic electron beam has been studied in experiments in the large vacuum chamber at Johnson Space Center. The introduction of an RF-discharge-produced ambient plasma density (10,000 to 50,000 per cu cm) reduces the payload potential to 200 V for low current (1 and 10 ma) beams. The ignition of the beam-plasma discharge provides an efficient neutralization process for higher current beams.

  5. Beam-Beam Interactions

    SciTech Connect

    Sramek, Christopher

    2003-09-05

    At the interaction point of a particle accelerator, various phenomena occur which are known as beam-beam effects. Incident bunches of electrons (or positrons) experience strong electromagnetic fields from the opposing bunches, which leads to electron deflection, beamstrahlung and the creation of electron/positron pairs and hadrons due to two-photon exchange. In addition, the beams experience a ''pinch effect'' which focuses each beam and results in either a reduction or expansion of their vertical size. Finally, if a beam's disruption parameter is too large, the beam can develop a sinusoidal distortion, or two-stream (kink) instability. This project simulated and studied these effects as they relate to luminosity, deflection angles and energy loss in order to optimize beam parameters for the Next Linear Collider (NLC). Using the simulation program Guinea-Pig, luminosity, deflection angle and beam energy data was acquired for different levels of beam offset and distortion. Standard deflection curves and luminosity plots agreed with theoretical models but also made clear the difficulties of e-e- feedback. Simulations emphasizing kink instability in modulated and straight beam collisions followed qualitative behavioral predictions and roughly fit recent analytic calculations. Finally, a study of e-e- collisions under design constraints for the NLC provided new estimates of how luminosity, beamstrahlung energy loss, upsilon parameter and deflection curve width scale with beam spotsizes.

  6. Energy deposition studies for the LBNE beam absorber

    SciTech Connect

    Rakhno, Igor L.; Mokhov, Nikolai V.; Tropin, Igor S.

    2015-01-29

    Results of detailed Monte Carlo energy deposition studies performed for the LBNE absorber core and the surrounding shielding with the MARS15 code are described. The model of the entire facility, that includes a pion-production target, focusing horns, target chase, decay channel, hadron absorber system – all with corresponding radiation shielding – was developed using the recently implemented ROOT-based geometry option in the MARS15 code. This option provides substantial flexibility and automation when developing complex geometry models. Both normal operation and accidental conditions were studied. Various design options were considered, in particular the following: (i) filling the decay pipe with air or helium; (ii) the absorber mask material and shape; (iii) the beam spoiler material and size. Results of detailed thermal calculations with the ANSYS code helped to select the most viable absorber design options.

  7. Beam feasibility study of a collimator with in-jaw beam position monitors

    NASA Astrophysics Data System (ADS)

    Wollmann, Daniel; Nosych, Andriy A.; Valentino, Gianluca; Aberle, Oliver; Aßmann, Ralph W.; Bertarelli, Alessandro; Boccard, Christian; Bruce, Roderik; Burkart, Florian; Calvo, Eva; Cauchi, Marija; Dallocchio, Alessandro; Deboy, Daniel; Gasior, Marek; Jones, Rhodri; Kain, Verena; Lari, Luisella; Redaelli, Stefano; Rossi, Adriana

    2014-12-01

    At present, the beam-based alignment of the LHC collimators is performed by touching the beam halo with both jaws of each collimator. This method requires dedicated fills at low intensities that are done infrequently and makes this procedure time consuming. This limits the operational flexibility, in particular in the case of changes of optics and orbit configuration in the experimental regions. The performance of the LHC collimation system relies on the machine reproducibility and regular loss maps to validate the settings of the collimator jaws. To overcome these limitations and to allow a continuous monitoring of the beam position at the collimators, a design with jaw-integrated Beam Position Monitors (BPMs) was proposed and successfully tested with a prototype (mock-up) collimator in the CERN SPS. Extensive beam experiments allowed to determine the achievable accuracy of the jaw alignment for single and multi-turn operation. In this paper, the results of these experiments are discussed. The non-linear response of the BPMs is compared to the predictions from electromagnetic simulations. Finally, the measured alignment accuracy is compared to the one achieved with the present collimators in the LHC.

  8. Lifetime carcinogenesis studies of chrysotile asbestos (CAS No. 12001-29-5) in syrian golden hamsters (feed studies). Technical report series

    SciTech Connect

    Not Available

    1990-07-01

    Carcinogenesis studies of short range (SR), intermediate range (IR) or intermediate range chrysotile asbestos in combination with the intestinal carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) were conducted with male and female Syrian golden hamsters. Both forms of chrysotile asbestos were administered at a concentration of 1% in pelleted diet for the entire lifetime of the hamsters, starting with mothers of the test animals. Group sizes varied from 125 to 253. Starting at 6 weeks of age, male and female hamsters in the intermediate range chrysotile/DMH study were given oral doses of DMH (4 mg/kg) every other week for a total of 5 doses. There was no adverse effect on body weight gain or survival by either form of asbestos or by asbestos in combination with DMH. Under the conditions of these studies, neither short range chrysotile nor intermediate range chrysotile asbestos was carcinogenic when ingested at 1% levels in the diet by male and female Syrian golden hamsters. While there were increases in the rates of adrenal cortical adenomas in male and female hamsters exposed to intermediate range chrysotile asbestos compared with pooled control groups, these incidence rates were not different when compared with the concurrent control groups. Additionally, the biologic importance of adrenal tumors in the absence of target organ (gastrointestinal tract) neoplasia is questionable.

  9. The association of lifetime insight and cognition in psychosis.

    PubMed

    Sánchez-Torres, Ana M; Zarzuela, Amalia; Peralta, Victor; Cuesta, Manuel J

    2015-03-01

    Poor insight has been related to poor course in psychosis. However, the role of cognition in insight remains unclear. The aim of this study was to examine the influence of cognition and lifetime psychopathological dimensions on insight in psychosis. We followed up 42 patients with psychotic disorders over 10years. Lifetime psychopathological dimensions and cognitive performance were assessed. Patients were divided into two groups by lifetime patterns of insight and compared with 42 healthy volunteers. Lower IQ and poorer social cognition were associated with higher risks of poorer lifetime insight of feeling ill and global insight respectively. Lifetime negative symptoms were associated with a higher risk of poorer lifetime insight into symptoms. Lifetime lack of insight is independent of cognitive impairment in specific domains, except for social cognition. Higher IQ may contribute to better lifetime awareness of illness, while better ability to manage emotions is involved in lifetime global insight.

  10. Fluorescence lifetime measurements in flow cytometry

    NASA Astrophysics Data System (ADS)

    Beisker, Wolfgang; Klocke, Axel

    1997-05-01

    Fluorescence lifetime measurements provide insights int eh dynamic and structural properties of dyes and their micro- environment. The implementation of fluorescence lifetime measurements in flow cytometric systems allows to monitor large cell and particle populations with high statistical significance. In our system, a modulated laser beam is used for excitation and the phase shift of the fluorescence signal recorded with a fast computer controlled digital oscilloscope is processed digitally to determine the phase shift with respect to a reference beam by fast fourier transform. Total fluorescence intensity as well as other parameters can be determined simultaneously from the same fluorescence signal. We use the epi-illumination design to allow the use of high numerical apertures to collect as much light as possible to ensure detection of even weak fluorescence. Data storage and processing is done comparable to slit-scan flow cytometric data using data analysis system. The results are stored, displayed, combined with other parameters and analyzed as normal listmode data. In our report we discuss carefully the signal to noise ratio for analog and digital processed lifetime signals to evaluate the theoretical minimum fluorescence intensity for lifetime measurements. Applications to be presented include DNA staining, parameters of cell functions as well as different applications in non-mammalian cells such as algae.

  11. A review of dosimetry studies on external-beam radiation treatment with respect to second cancer induction

    PubMed Central

    Xu, X George; Bednarz, Bryan; Paganetti, Harald

    2014-01-01

    It has been long known that patients treated with ionizing radiation carry a risk of developing a second cancer in their lifetimes. Factors contributing to the recently renewed concern about the second cancer include improved cancer survival rate, younger patient population as well as emerging treatment modalities such as intensity-modulated radiation treatment (IMRT) and proton therapy that can potentially elevate secondary exposures to healthy tissues distant from the target volume. In the past 30 years, external-beam treatment technologies have evolved significantly, and a large amount of data exist but appear to be difficult to comprehend and compare. This review article aims to provide readers with an understanding of the principles and methods related to scattered doses in radiation therapy by summarizing a large collection of dosimetry and clinical studies. Basic concepts and terminology are introduced at the beginning. That is followed by a comprehensive review of dosimetry studies for external-beam treatment modalities including classical radiation therapy, 3D-conformal x-ray therapy, intensity-modulated x-ray therapy (IMRT and tomotherapy) and proton therapy. Selected clinical data on second cancer induction among radiotherapy patients are also covered. Problems in past studies and controversial issues are discussed. The needs for future studies are presented at the end. PMID:18540047

  12. TOPICAL REVIEW: A review of dosimetry studies on external-beam radiation treatment with respect to second cancer induction

    NASA Astrophysics Data System (ADS)

    Xu, X. George; Bednarz, Bryan; Paganetti, Harald

    2008-07-01

    It has been long known that patients treated with ionizing radiation carry a risk of developing a second cancer in their lifetimes. Factors contributing to the recently renewed concern about the second cancer include improved cancer survival rate, younger patient population as well as emerging treatment modalities such as intensity-modulated radiation treatment (IMRT) and proton therapy that can potentially elevate secondary exposures to healthy tissues distant from the target volume. In the past 30 years, external-beam treatment technologies have evolved significantly, and a large amount of data exist but appear to be difficult to comprehend and compare. This review article aims to provide readers with an understanding of the principles and methods related to scattered doses in radiation therapy by summarizing a large collection of dosimetry and clinical studies. Basic concepts and terminology are introduced at the beginning. That is followed by a comprehensive review of dosimetry studies for external-beam treatment modalities including classical radiation therapy, 3D-conformal x-ray therapy, intensity-modulated x-ray therapy (IMRT and tomotherapy) and proton therapy. Selected clinical data on second cancer induction among radiotherapy patients are also covered. Problems in past studies and controversial issues are discussed. The needs for future studies are presented at the end.

  13. Experimental studies of SPECT scintimammography with combined cone-beam and parallel-beam collimators

    NASA Astrophysics Data System (ADS)

    Krol, Andrzej; Feiglin, David H.; Gangal, K. R.; Coman, Ioana L.; Salgado, Roberto B.; Lipson, Edward D.; Karczewski, Deborah A.; Thomas, Frank D.

    2003-05-01

    Conventional SPECT Tc-99m sestamibi scintimammography (STSM) has limited clinical utility due to fairly low radiopharmaceutical uptake in the breast tissue as compared to the heart and the liver. We investigated the use of a cone-beam collimator (CBC) to STSM. Each detector on a multi-headed gamma camera can be equipped with parallel-beam (PBC) or cone-beam collimators (CBC). PBC can provide truncation-free SPECT projection sets, while CBC offers increased sensitivity in a limited field-of-view (FOV). Combined PBC and CBC SPECT ddata acquisition may provide improved lesion contrast and overall better imaging performance within CBC FOV with significantly reduced truncation artifacts in the reconstructed images. In this paper we evaluate the combined CBC&PBC SPECT method using a limited number of confirmed breast cancer patients and female chest phantoms with simulated breast lesions. We envision the combined CBC&PBC SPECT as a useful clinical tool in scintimammography.

  14. Analog detection for cavity lifetime spectroscopy

    DOEpatents

    Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

    2001-05-15

    An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

  15. Analog detection for cavity lifetime spectroscopy

    DOEpatents

    Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

    2003-01-01

    An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

  16. Collisional lifetimes of meteoroids

    NASA Astrophysics Data System (ADS)

    Soja, R. H.; Schwarzkopf, G. J.; Sommer, M.; Vaubaillon, J.; Albin, T.; Rodmann, J.; Grün, E.; Srama, R.

    2016-01-01

    Collisions of meteoroids with interplanetary dust grain fragments particles, dispersing larger particles amongst lower mass intervals. Here we use the method of Grün et al. (1985) and the IMEM interplanetary dust model to calculate the collisional lifetimes for different orbits, and for particles in different meteor showers. The timescales are usually long - of order 10^4 years for 1mm grains on Jupiter-family and Hally-type comet orbits. However, near-sun orbits particles suffer more frequent collisions and therefore have much shorter lifetimes. We discuss factors that affect the accuracy of these calculations.

  17. Study on electron beam in a low energy plasma focus

    SciTech Connect

    Khan, Muhammad Zubair; Ling, Yap Seong; San, Wong Chiow

    2014-03-05

    Electron beam emission was investigated in a low energy plasma focus device (2.2 kJ) using copper hollow anode. Faraday cup was used to estimate the energy of the electron beam. XR100CR X-ray spectrometer was used to explore the impact of the electron beam on the target observed from top-on and side-on position. Experiments were carried out at optimized pressure of argon gas. The impact of electron beam is exceptionally notable with two different approaches using lead target inside hollow anode in our plasma focus device.

  18. Transverse and longitudinal beam dynamics studies at the Fermilab photoinjector

    SciTech Connect

    Carneiro, J.P.; Barov, N.; Edwards, H.; Fitch, M.; Hartung, W.; Flottmann, K.; Schreiber, S.; Ferrario, M.; /Frascati

    2005-01-01

    The Fermilab photoinjector produces electron bunches of 1-12 nC charge with an energy of 16-18 MeV. Detailed measurements and optimization of the transverse emittance have been carried out for a number of beam line optics conditions, and at a number of beam line locations. The length of the bunches has also been measured, first for an uncompressed beam (as a function of the charge) and then for a compressed beam of 8 nC charge (as a function of the 9-cell cavity phase). These measurements are presented and compared with the simulation codes HOMDYN and ASTRA.

  19. Stoichiometry dependence of the optical and minority-carrier lifetime behaviors of CdTe epitaxial films: A low-temperature and time-resolved photoluminescence study

    NASA Astrophysics Data System (ADS)

    Tang, Kai; Zhu, Xuanting; Zhu, Liangqing; Bai, Wei; Bai, Jiawei; Dong, Wenxia; Yang, Jing; Zhang, Yuanyuan; Chen, Ye; Tang, Xiaodong; Chu, Junhao

    2016-11-01

    Cadmium telluride (CdTe) epitaxial films (EFs) were grown on near-lattice-matched Cd0.96Zn0.04Te (CZT) substrates by molecular beam epitaxy at different ambients to achieve Cd-rich samples with extra Cd molecular flux or Te-rich samples with extra Te molecular flux. The evolution of epitaxial growth was in situ monitored by reflection high-energy electron diffraction (RHEED). A two-dimensional growth mode was indicated by the streaky RHEED patterns. Crystal structures of the CdTe EFs were characterised by X-ray diffraction (XRD). XRD data suggested that the crystal quality of the CdTe EFs was improved by controlling the Cd and Te flux ratio. Low-temperature photoluminescence (PL) spectra were carried out in these CdTe EFs. The typical characteristic peak at ∼1.552 eV denoted as the bound-to-free transition was only found in CdTe samples grown under an extra Cd flux, and Cd vacancy-related defects were absent in the Cd-rich EFs, confirming the Cd-rich or Te-rich states of the epitaxial CdTe films. Finally, minority-carrier lifetime was prolonged in Cd-rich CdTe EFs as supported by time-resolved photoluminescence (TRPL) measurement.

  20. Radiological Studies for the LCLS Beam Abort System

    SciTech Connect

    Santana Leitner, M.; Vollaire, J.; Mao, X.S.

    2008-03-25

    The Linac Coherent Light Source (LCLS), a pioneer hard x-ray free electron laser is currently under construction at the Stanford Linear Accelerator Center. It is expected that by 2009 LCLS will deliver laser pulses of unprecedented brightness and short length, which will be used in several forefront research applications. This ambitious project encompasses major design challenges to the radiation protection like the numerous sources and the number of surveyed objects. In order to sort those, the showers from various loss sources have been tracked along a detailed model covering 1/2 mile of LCLS accelerator by means of the Monte Carlo intra nuclear cascade codes FLUKA and MARS15. This article covers the FLUKA studies of heat load; prompt and residual dose and environmental impact for the LCLS beam abort system.

  1. Direct reaction experimental studies with beams of radioactive tin ions

    SciTech Connect

    Jones, K. L. Ayres, A.; Bey, A.; Burcher, S.; Cartegni, L.; Cerizza, G.; Ahn, S.; Allmond, J. M.; Beene, J. R.; Galindo-Uribarri, A.; Liang, J. F.; Nesaraja, C. D.; Pain, S. D.; Radford, D. C.; Schmitt, K. T.; Smith, M. S.; Stracener, D. W.; Varner, R. L.; Bardayan, D. W.; Baugher, T.; and others

    2015-10-15

    The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at {sup 100}Sn, through 10 stable isotopes and the N = 82 shell closure at {sup 132}Sn out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich {sup 130}Sn. Both techniques rely on selective particle identification and the measurement of γ rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications.

  2. Direct Reaction Experimental Studies with Beams of Radioactive Tin Ions

    SciTech Connect

    Jones, K. L.; Ahn, S.H.; Allmond, James M; Ayres, A.; Bardayan, Daniel W; Baugher, T.; Bazin, D.; Beene, James R; Berryman, J. S.; Bey, A.; Bingham, C. R.; Cartegni, L.; Chae, K. Y.; Gade, A.; Galindo-Uribarri, Alfredo {nmn}; Garcia-Ruiz, R.F.; Grzywacz, Robert Kazimierz; Howard, Meredith E; Kozub, R. L.; Liang, J Felix; Manning, Brett M; Matos, M.; McDaniel, S.; Miller, D.; Nesaraja, Caroline D; O'Malley, Patrick; Padgett, S; Padilla-Rodal, Elizabeth; Pain, Steven D; Pittman, S. T.; Radford, David C; Ratkiewicz, Andrew J; Schmitt, Kyle; Smith, Michael Scott; Stracener, Daniel W; Stroberg, S.; Tostevin, Jeffrey A; Varner Jr, Robert L; Weisshaar, D.; Wimmer, K.

    2015-01-01

    The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at Sn-100, through 10 stable isotopes and the N = 82 shell closure at Sn-132 out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic nuclei. Here we present one experiment knocking out neutrons from tin isotopes that are already neutron deficient and two reactions that add a neutron to neutron-rich Sn-130. Both techniques rely on selective particle identification and the measurement of gamma rays in coincidence with charged ions. We present the goals of the two experiments and the particle identification for the channels of interest. The final results will be presented in future publications.

  3. Comments on Injector Proton Beam Study in Run 2014

    SciTech Connect

    Zhang, S. Y.

    2014-09-15

    During the entire period of injector proton study in run 2014, it seems that the beam transverse emittance out of Booster is larger than that in run 2013. The emittance measured at the BtA transfer line and also the transmission from Booster late to AGS late are presented for this argument. In addition to this problem, it seems that the multiturn Booster injection, which defines the transverse emittance, needs more attention. Moreover, for high intensity operations, the space charge effect may be already relevant in RHIC polarized proton runs. With the RHIC proton intensity improvement in the next several years, higher Booster input intensity is needed, therefore, the space charge effect at the Booster injection and early ramp may become a new limiting factor.

  4. Study of nanoscale structural biology using advanced particle beam microscopy

    NASA Astrophysics Data System (ADS)

    Boseman, Adam J.

    This work investigates developmental and structural biology at the nanoscale using current advancements in particle beam microscopy. Typically the examination of micro- and nanoscale features is performed using scanning electron microscopy (SEM), but in order to decrease surface charging, and increase resolution, an obscuring conductive layer is applied to the sample surface. As magnification increases, this layer begins to limit the ability to identify nanoscale surface structures. A new technology, Helium Ion Microscopy (HIM), is used to examine uncoated surface structures on the cuticle of wild type and mutant fruit flies. Corneal nanostructures observed with HIM are further investigated by FIB/SEM to provide detailed three dimensional information about internal events occurring during early structural development. These techniques are also used to reconstruct a mosquito germarium in order to characterize unknown events in early oogenesis. Findings from these studies, and many more like them, will soon unravel many of the mysteries surrounding the world of developmental biology.

  5. Cherenkov excited phosphorescence-based pO2 estimation during multi-beam radiation therapy: phantom and simulation studies.

    PubMed

    Holt, Robert W; Zhang, Rongxiao; Esipova, Tatiana V; Vinogradov, Sergei A; Glaser, Adam K; Gladstone, David J; Pogue, Brian W

    2014-09-21

    Megavoltage radiation beams used in External Beam Radiotherapy (EBRT) generate Cherenkov light emission in tissues and equivalent phantoms. This optical emission was utilized to excite an oxygen-sensitive phosphorescent probe, PtG4, which has been developed specifically for NIR lifetime-based sensing of the partial pressure of oxygen (pO2). Phosphorescence emission, at different time points with respect to the excitation pulse, was acquired by an intensifier-gated CCD camera synchronized with radiation pulses delivered by a medical linear accelerator. The pO2 distribution was tomographically recovered in a tissue-equivalent phantom during EBRT with multiple beams targeted from different angles at a tumor-like anomaly. The reconstructions were tested in two different phantoms that have fully oxygenated background, to compare a fully oxygenated and a fully deoxygenated inclusion. To simulate a realistic situation of EBRT, where the size and location of the tumor is well known, spatial information of a prescribed region was utilized in the recovery estimation. The phantom results show that region-averaged pO2 values were recovered successfully, differentiating aerated and deoxygenated inclusions. Finally, a simulation study was performed showing that pO2 in human brain tumors can be measured to within 15 mmHg for edge depths less than 10-20 mm using the Cherenkov Excited Phosphorescence Oxygen imaging (CEPhOx) method and PtG4 as a probe. This technique could allow non-invasive monitoring of pO2 in tumors during the normal process of EBRT, where beams are generally delivered from multiple angles or arcs during each treatment fraction.

  6. Ionization levels of As vacancies in as-grown GaAs studied by positron-lifetime spectroscopy

    SciTech Connect

    Saarinen, K.; Hautojaervi, P.; Lanki, P. ); Corbel, C. )

    1991-11-15

    The properties of the native monovacancy defects are systematically investigated by positron-lifetime measurements in {ital n}-type GaAs with carrier concentrations of {ital n}=10{sup 15--}10{sup 18} cm{sup {minus}3}. The native defects present two ionization levels at {ital E}{sub {ital C}}{minus}30 meV and {ital E}{sub {ital C}}{minus}140 meV. The first corresponds to a charge transition 1{minus}{r arrow}0 and the second to 0{r arrow}1+. The transitions are attributed to ionizations of As vacancy, which may be isolated or part of a complex. In a simple identification of the defect with {ital V}{sub As}, the ionization level at {ital E}{sub {ital C}}{minus}30 meV is attributed to the transition {ital V}{sub As}{sup {minus}}{r arrow}{ital V}{sub As}{sup 0} and the ionization level at {ital E}{sub {ital C}}{minus}140 meV to the transition {ital V}{sub As}{sup 0}{r arrow}{ital V}{sub As}{sup +}. The results show further that the configuration of {ital V}{sub As}{sup {minus}} is strongly relaxed inwards compared to the structure of {ital V}{sub As}{sup 0}.

  7. Our Allotted Lifetimes

    ERIC Educational Resources Information Center

    Gould, Stephen Jay

    1977-01-01

    It is suggested that measured by the internal clock of heartbeats or breathing, all mammals live a similar lifespan. This is based on the fact that mammals, regardless of size, breathe about 200 million times in their lifetime at a rate of 1 breath for every 4 heartbeats. (AJ)

  8. Beam Simulation Studies of the LEBT for RIA Driver Linac

    SciTech Connect

    Zhao, Q.; Wu, X.; Andreev, V.; Balabin, A.; Doleans, M.; Gorelov, D.; Grimm, T.L.; Hartung, W.; Marti, F.; Schriber, S.O.; York, R.C.; Leitner, D.; Lyneis, C.M.

    2005-03-15

    The low energy beam transport (LEBT) system in the front-end of the Rare Isotope Accelerator (RIA) uses a 70 kV platform to pre-accelerate the ion beam from a 30 kV Electron Cyclotron Resonance (ECR) ion source, followed by an achromatic charge selection system. The selected beam is then pre-bunched and matched into the entrance of a Radio Frequency Quadrupole (RFQ) with a multi-harmonic buncher. To meet the beam power requirements for heavy ions, high current (several mA), multi-species beams will be extracted from the ECR. Therefore, it is crucial to control space charge effects in order to obtain the low emittance beam required for RIA. The PARMELA code is used to perform the LEBT simulations for the multi-species beams with 3D space charge calculations. The results of the beam dynamics simulations are presented, and the key issues of emittance growth in the LEBT and its possible compensation are discussed.

  9. Initial beam size study for passive scatter proton therapy. II. Changes in delivered depth dose profiles

    SciTech Connect

    Polf, Jerimy C.; Harvey, Mark C.; Smith, Alfred R.

    2007-11-15

    In passively scattered proton radiotherapy, a clinically useful treatment beam is produced by spreading a small proton 'pencil beam' extracted from the accelerator to create both a uniform dose profile laterally and a uniform spread-out Bragg peak (SOBP) in depth. Lateral spreading and range modulation of the beam are accomplished using specially designed components within the treatment delivery nozzle. The purpose of this study was to determine how changes in the size of the initial proton pencil beam affect the delivery of dose with a passive scatter treatment nozzle. Monte Carlo calculations were used to study changes of the beam's in-air energy distribution at the exit of the nozzle and the central axis depth dose profiles in water resulting from changes in the incident beam size. Our results indicate that the width of the delivered SOBP decreases as the size of the initial beam increases.

  10. Experimental study of thin-walled composite beams

    NASA Technical Reports Server (NTRS)

    Chandra, Ramesh; Ngo, Hieu; Chopra, Inderjit

    1988-01-01

    Thin-walled rectangular section composite beams are built out of graphite-epoxy prepreg tape using an autoclave molding technique. Cantilevered beams are tested under static loads using a specially-built apparatus and bending slope and elastic twist at a station are measured using a laser system. Measured bending slope and bending-induced twist distributions are correlated with predicted results obtained using a simple beam analysis as well as a refined finite element analysis. Natural vibration characteristics at different rotational speeds are determined experimentally by testing beams in a specially built 10 ft diameter vacuum chamber. The rotor is excited by piezo-electric crystals and response is determined from strain gages mounted on the surface. For composite beams with bending-twisting couplings (symmetric layup), effects of section warping and transverse shear on structural response are found to be substantial. These results were substantiated by the analyses.

  11. Lifetime of MCP-PMTs

    NASA Astrophysics Data System (ADS)

    Lehmann, A.; Britting, A.; Eyrich, W.; Pfaffinger, M.; Uhlig, F.; Belias, A.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Kalicy, G.; Krebs, M.; Lehmann, D.; Nerling, F.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Zühlsdorf, M.; Düren, M.; Etzelmüller, E.; Föhl, K.; Hayrapetyan, A.; Kröck, B.; Merle, O.; Rieke, J.; Schmidt, M.; Cowie, E.; Keri, T.; Achenbach, P.; Cardinali, M.; Hoek, M.; Lauth, W.; Schlimme, S.; Sfienti, C.; Thiel, M.

    2016-05-01

    The hadron identification in the PANDA experiment at FAIR will be done with DIRC detectors. Because of design and space reasons the sensors of the DIRCs have to be placed inside the strong magnetic field of the solenoid. As the favored photon sensors microchannel-plate photomultipliers (MCP-PMTs) were identified. However, these devices showed serious aging problems until very recently, which manifest themselves by a fast degrading quantum efficiency (QE) of the photo cathode (PC). This is mainly due to feedback ions from the residual gas. In this paper we discuss the recently accomplished huge improvements in the lifetime of MCP-PMTs. With innovative countermeasures applied to the MCP-PMTs in the attempt to reduce the aging effects the manufacturers were able to increase the lifetime of MCP-PMT prototypes by almost two orders of magnitude compared to the former commercially available devices. Our group has studied the aging of MCP-PMTs for more than four years by simultaneously illuminating different types of lifetime-enhanced MCP-PMTs at the same photon rate. Gain, dark count rate, and QE as a function of the wavelength and the PC surface were measured in regular time intervals and studied in dependence of the integrated anode charge. We observe that MCP-PMTs treated with an atomic layer deposition (ALD) technique are by far the best devices available now. A lifetime of up to 10 C/cm2 integrated anode charge was reached with these sensors. This is sufficient for both PANDA DIRCs.

  12. Estimating the lifetime economic burden of stroke according to the age of onset in South Korea: a cost of illness study

    PubMed Central

    2011-01-01

    Background The recently-observed trend towards younger stroke patients in Korea raises economic concerns, including erosion of the workforce. We compared per-person lifetime costs of stroke according to the age of stroke onset from the Korean societal perspective. Methods A state-transition Markov model consisted of three health states ('post primary stroke event', 'alive post stroke', and 'dead') was developed to simulate the natural history of stroke. The transition probabilities for fatal and non-fatal recurrent stroke by age and gender and for non-stroke causes of death were derived from the national epidemiologic data of the Korean Health Insurance Review and Assessment Services and data from the Danish Monitoring Trends in Cardiovascular Disease study. We used an incidence-based approach to estimate the long-term costs of stroke. The model captured stroke-related costs including costs within the health sector, patients' out-of-pocket costs outside the health sector, and costs resulting from loss of productivity due to morbidity and premature death using a human capital approach. Average insurance-covered costs occurring within the health sector were estimated from the National Health Insurance claims database. Other costs were estimated based on the national epidemiologic data and literature. All costs are presented in 2008 Korean currency values (Korean won = KRW). Results The lifetime costs of stroke were estimated to be: 200.7, 81.9, and 16.4 million Korean won (1,200 KRW is approximately equal to one US dollar) for men who suffered a first stroke at age 45, 55 and 65 years, respectively, and 75.7, 39.2, and 19.3 million KRW for women at the same age. While stroke occurring among Koreans aged 45 to 64 years accounted for only 30% of the total disease incidence, this age group incurred 75% of the total national lifetime costs of stroke. Conclusions A higher lifetime burden and increasing incidence of stroke among younger Koreans highlight the need for more

  13. Lifetime exposure to arsenic in drinking water and bladder cancer: a population-based case–control study in Michigan, USA

    PubMed Central

    Slotnick, Melissa J.; AvRuskin, Gillian A.; Schottenfeld, David; Jacquez, Geoffrey M.; Wilson, Mark L.; Goovaerts, Pierre; Franzblau, Alfred; Nriagu, Jerome O.

    2014-01-01

    Objective Arsenic in drinking water has been linked with the risk of urinary bladder cancer, but the dose–response relationships for arsenic exposures below 100 µg/L remain equivocal. We conducted a population-based case–control study in southeastern Michigan, USA, where approximately 230,000 people were exposed to arsenic concentrations between 10 and 100 µg/L. Methods This study included 411 bladder cancer cases diagnosed between 2000 and 2004, and 566 controls recruited during the same period. Individual lifetime exposure profiles were reconstructed, and residential water source histories, water consumption practices, and water arsenic measurements or modeled estimates were determined at all residences. Arsenic exposure was estimated for 99% of participants’ person-years. Results Overall, an increase in bladder cancer risk was not found for time-weighted average lifetime arsenic exposure >10 µg/L when compared with a reference group exposed to <1 µg/L (odds ratio (OR) = 1.10; 95% confidence interval (CI): 0.65, 1.86). Among ever-smokers, risks from arsenic exposure >10 µg/L were similarly not elevated when compared to the reference group (OR = 0.94; 95% CI: 0.50, 1.78). Conclusions We did not find persuasive evidence of an association between low-level arsenic exposure and bladder cancer. Selecting the appropriate exposure metric needs to be thoughtfully considered when investigating risk from low-level arsenic exposure. PMID:20084543

  14. Comparative study of beam losses and heat loads reduction methods in MITICA beam source

    SciTech Connect

    Sartori, E. Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Veltri, P.; Sonato, P.

    2014-02-15

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  15. Comparative study of beam losses and heat loads reduction methods in MITICA beam source

    NASA Astrophysics Data System (ADS)

    Sartori, E.; Agostinetti, P.; Dal Bello, S.; Marcuzzi, D.; Serianni, G.; Sonato, P.; Veltri, P.

    2014-02-01

    In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

  16. Experimental Studies on Behaviour of Reinforced Geopolymer Concrete Beams Subjected to Monotonic Static Loading

    NASA Astrophysics Data System (ADS)

    Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Ramesh, G.

    2015-06-01

    This work describes the experimental investigation on behaviour of reinforced GPC beams subjected to monotonic static loading. The overall dimensions of the GPC beams are 250 mm × 300 mm × 2200 mm. The effective span of beam is 1600 mm. The beams have been designed to be critical in shear as per IS:456 provisions. The specimens were produced from a mix incorporating fly ash and ground granulated blast furnace slag, which was designed for a compressive strength of 40 MPa at 28 days. The reinforced concrete specimens are subjected to curing at ambient temperature under wet burlap. The parameters being investigated include shear span to depth ratio (a/d = 1.5 and 2.0). Experiments are conducted on 12 GPC beams and four OPCC control beams. All the beams are tested using 2000 kN servo-controlled hydraulic actuator. This paper presents the results of experimental studies.

  17. Emittance and lifetime measurement with damping wigglers

    NASA Astrophysics Data System (ADS)

    Wang, G. M.; Shaftan, T.; Cheng, W. X.; Guo, W.; Ilinsky, P.; Li, Y.; Podobedov, B.; Willeke, F.

    2016-03-01

    National Synchrotron Light Source II (NSLS-II) is a new third-generation storage ring light source at Brookhaven National Laboratory. The storage ring design calls for small horizontal emittance (<1 nm-rad) and diffraction-limited vertical emittance at 12 keV (8 pm-rad). Achieving low value of the beam size will enable novel user experiments with nm-range spatial and meV-energy resolution. The high-brightness NSLS-II lattice has been realized by implementing 30-cell double bend achromatic cells producing the horizontal emittance of 2 nm rad and then halving it further by using several Damping Wigglers (DWs). This paper is focused on characterization of the DW effects in the storage ring performance, namely, on reduction of the beam emittance, and corresponding changes in the energy spread and beam lifetime. The relevant beam parameters have been measured by the X-ray pinhole camera, beam position monitors, beam filling pattern monitor, and current transformers. In this paper, we compare the measured results of the beam performance with analytic estimates for the complement of the 3 DWs installed at the NSLS-II.

  18. Low-level chronic exposure to cadmium enhances the risk of long bone fractures: a study on a female rat model of human lifetime exposure.

    PubMed

    Brzóska, Malgorzata M

    2012-01-01

    In the present paper, the hypothesis that low chronic exposure to cadmium (Cd) enhances the risk of long bone fractures was investigated in a female rat model simulating human lifetime exposure in non-Cd-polluted areas. For this purpose, the femur and both tibias of control female rats and those exposed to Cd (1 mg Cd I(-1) in drinking water for 24 months since weaning) were assigned to geometric, densitometric (bone mineral content, BMC, and density, BMD), radiographic and biomechanical studies as well as assessing their chemical composition. The exposure to Cd disturbed mineralization (decreased BMD and minerals content, including calcium, magnesium, zinc, copper and iron) and weakened the biomechanical strength of the femur and tibia, enhancing their fragility. The Z-score values for the BMD revealed osteopenia of the femur and tibia in 20 and 30% of the Cd-exposed female rats, respectively, and osteoporosis in 80 and 70%, respectively. In 30% of the Cd-exposed animals, femoral neck fracture was evident in the radiographic picture. The findings seem to confirm the hypothesis that a low exposure to Cd during the lifetime may be an important risk factor for osteoporosis and fractures of long bones, and especially for femoral neck fracture in elderly women. The results indicate that greater attention should be paid to Cd as an environmental risk factor for the increasing rate of osteoporosis and bone fractures in old population.

  19. Studies on space charge neutralization and emittance measurement of beam from microwave ion source

    SciTech Connect

    Misra, Anuraag; Goswami, A.; Sing Babu, P.; Srivastava, S.; Pandit, V. S. E-mail: vspandit12@gmail.com

    2015-11-15

    A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (∼5 mA at 75 keV), it is possible to reduce the beam spot size by ∼34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results.

  20. Performance Studies of the Vibration Wire Monitor on the Test Stand with Low Energy Electron Beam

    NASA Astrophysics Data System (ADS)

    Okabe, Kota; Yoshimoto, Masahiro; Kinsho, Michikazu

    In the high intensity proton accelerator as the Japan Proton Accelerator Research Complex (J-PARC) accelerators, serious radiation and residual dose is induced by a small beam loss such a beam halo. Therefore, diagnostics of the beam halo formation is one of the most important issues to control the beam loss. For the beam halo monitor, the vibration wire monitor (VWM) has a potential for investigating the beam halo and weak beam scanning. The VWM has a wide dynamic range, high resolution and the VWM is not susceptible to secondary electrons and electric noises. We have studied the VWM features as a new beam-halo monitor on the test stand with low energy electron gun. The frequency shift of the irradiated vibration wire was confirmed about wire material and the electron beam profile measured by using the VWM was consistent with the results of the Faraday cup measurement. Also we calculated a temperature distribution on the vibration wire which is irradiated by the electron beam with the numerical simulation. The simulations have been fairly successful in reproducing the transient of the irradiated vibration wire frequency measured by test stand experiments. In this paper, we will report a result of performance evaluation for the VWM on the test stands and discuss the VWM for beam halo diagnostic

  1. Studies on space charge neutralization and emittance measurement of beam from microwave ion source.

    PubMed

    Misra, Anuraag; Goswami, A; Sing Babu, P; Srivastava, S; Pandit, V S

    2015-11-01

    A 2.45 GHz microwave ion source together with a beam transport system has been developed at VECC to study the problems related with the injection of high current beam into a compact cyclotron. This paper presents the results of beam profile measurement of high current proton beam at different degrees of space charge neutralisation with the introduction of neon gas in the beam line using a fine leak valve. The beam profiles have been measured at different pressures in the beam line by capturing the residual gas fluorescence using a CCD camera. It has been found that with space charge compensation at the present current level (∼5 mA at 75 keV), it is possible to reduce the beam spot size by ∼34%. We have measured the variation of beam profile as a function of the current in the solenoid magnet under the neutralised condition and used these data to estimate the rms emittance of the beam. Simulations performed using equivalent Kapchinsky-Vladimirsky beam envelope equations with space charge neutralization factor are also presented to interpret the experimental results. PMID:26628123

  2. Three-dimensional fluorescence lifetime tomography

    SciTech Connect

    Godavarty, Anuradha; Sevick-Muraca, Eva M.; Eppstein, Margaret J.

    2005-04-01

    Near-infrared fluorescence tomography using molecularly targeted lifetime-sensitive, fluorescent contrast agents have applications for early-stage cancer diagnostics. Yet, although the measurement of fluorescent lifetime imaging microscopy (FLIM) is extensively used in microscopy and spectroscopy applications, demonstration of fluorescence lifetime tomography for medical imaging is limited to two-dimensional studies. Herein, the feasibility of three-dimensional fluorescence-lifetime tomography on clinically relevant phantom volumes is established, using (i) a gain-modulated intensified charge coupled device (CCD) and modulated laser diode imaging system, (ii) two fluorescent contrast agents, e.g., Indocyanine green and 3-3'-Diethylthiatricarbocyanine iodide differing in their fluorescence lifetime by 0.62 ns, and (iii) a two stage approximate extended Kalman filter reconstruction algorithm. Fluorescence measurements of phase and amplitude were acquired on the phantom surface under different target to background fluorescence absorption (70:1, 100:1) and fluorescence lifetime (1:1, 2.1:1) contrasts at target depths of 1.4-2 cm. The Bayesian tomography algorithm was employed to obtain three-dimensional images of lifetime and absorption owing to the fluorophores.

  3. Nuclear Astrophysics and Structure Studies Using Low-energy RI Beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.

    2010-05-12

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Using the RI beams at CRIB, Many measurements on proton and alpha resonance scatterings, (alpha,p) reactions, and others were peformed in recent years, mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the {sup 7}Be+p and {sup 7}Li+alpha resonance scatterings are presented.

  4. Nuclear Astrophysics and Structure Studies Using Low-energy RI Beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.

    2010-05-01

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Using the RI beams at CRIB, Many measurements on proton and alpha resonance scatterings, (α,p) reactions, and others were peformed in recent years, mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the 7Be+p and 7Li+α resonance scatterings are presented.

  5. Nuclear clusters studied with alpha resonant scatterings using RI beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Teranishi, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. N.; Kubono, S.; Suhara, T.; Kanada-En'yo, Y.; Moon, J. Y.; Kim, A.; Iwasa, N.; Lee, P. S.; Chae, K. Y.; Cha, S. M.; Gwak, M. S.; Kim, D. H.; Milman, E.

    2014-12-01

    Alpha resonant scattering is a simple and promising method to study α-cluster structure in nuclei. It has several good features which enable us to perform measurements with short-lived and relatively low-intense RI beams. Several measurements on alpha resonant scattering have been carried out at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. Recent α resonant scattering studies at CRIB, using 7Li, 7Be and 10Be beams with a helium gas target, are discussed.

  6. Molecular-beam Studies of Primary Photochemical Processes

    DOE R&D Accomplishments Database

    Lee, Y. T.

    1982-12-01

    Application of the method of molecular-beam photofragmentation translational spectroscopy to the investigation of primary photochemical processes of polyatomic molecules is described. Examples will be given to illustrate how information concerning the energetics, dynamics, and mechanism of dissociation processes can be obtained from the precise measurements of angular and velocity distributions of products in an experiment in which a well-defined beam of molecules is crossed with a laser.

  7. Status of LHC crab activity simulations and beam studies

    SciTech Connect

    Calaga,R.; Assman, R.; Barranco, J.; Barranco, J.; Calaga, R.; Caspers, F.; Ciapala, E.; De-Maria, R.; Koutchouk, J. P.; Linnecar, T.; Metral, E.; Morita, A.; Solyak, N.; Sun, Y.; Tomas, R.; Tuckmantel, J.; Weiler, T.; Zimmermann, F.

    2009-05-04

    The LHC crab cavity program is advancing rapidly towards a first prototype which is anticipated to be tested during the early stages of the LHC phase I upgrade and commissioning. The general project status and some aspects related to crab optics, collimation, aperture constraints, impedances, noise effects. beam transparency and machine protection critical for a safe and robust operation of LHC beams with crab cavities are addressed here.

  8. Studies on Neutral Beam Injection into the SSPX Spheromak Plasma

    SciTech Connect

    Jayakumar, R; Pearlstein, L D; Casper, T A; Fowler, T K; Hill, D N; Hudson, B; McLean, H; Moller, J

    2007-10-19

    In the Sustained Spheromak Physics Experiment, (SSPX) ['Improved operation of the SSPX spheromak', R.D. Wood, D.N. Hill, E.B. Hooper, S. Woodruff1, H.S. McLean and B.W. Stallard, Nucl. Fusion 45 1582-1588 (2005)], plasmas with core electron temperatures reaching up to 500 eV at densities of 10{sup 20}/m{sup 3} have been sustained for several milliseconds, making them suitable as targets for neutral beam injection. High performance and further progress in understanding Spheromak plasma physics are expected if neutral beams are injected into the plasma. This paper presents the results of numerical 1.5 D modeling of the plasma to calculate neutral beam current drive and ion and electron heating. The results are presented for varying initial conditions of density, temperatures and profiles and beam energy, injection angle and power. Current drive efficiency (Ampere/Watt of absorbed power) of up to 0.08 can be achieved with best performance SSPX shots as target. Analyses of neutral beam heating indicate that ion temperatures of up to 1.5 keV and electron temperatures of up to 750 eV can be obtained with injection of about 1 MW of neutral beam for 5-10 ms and with diffusivities typically observed in SSPX. Injection targeting near the magnetic axis appears to be the best for heating and current drive. Effect of the current drive and evolution of SSPX equilibrium are discussed.

  9. Feasibility study of optical/e-beam complementary lithography

    NASA Astrophysics Data System (ADS)

    Hohle, Christoph; Choi, Kang-Hoon; Freitag, Martin; Gutsch, Manuela; Jaschinsky, Philipp; Kahlenberg, Frank; Klein, Christof; Klikovits, Jan; Paul, Jan; Rudolph, Matthias; Thrun, Xaver

    2012-03-01

    Using electron beam direct write (EBDW) as a complementary approach together with standard optical lithography at 193nm or EUV wavelength has been proposed only lately and might be a reasonable solution for low volume CMOS manufacturing and special applications as well as design rule restrictions. Here, the high throughput of the optical litho can be combined with the high resolution and the high flexibility of the e-beam by using a mix & match approach (Litho- Etch-Litho-Etch, LELE). Complementary Lithography is mainly driven by special design requirements for unidirectional (1-D gridded) Manhattan type design layouts that enable scaling of advanced logic chips. This requires significant data prep efforts such as layout splitting. In this paper we will show recent results of Complementary Lithography using 193nm immersion generated 50nm lines/space pattern addressing the 32nm logic technology node that were cut with electron beam direct write. Regular lines and space arrays were patterned at GLOBALFOUNDRIES Dresden and have been cut in predefined areas using a VISTEC SB3050DW e-beam direct writer (50KV Variable Shaped Beam) at Fraunhofer Center Nanoelectronic Technologies (CNT), Dresden, as well as on the PML2 tool at IMS Nanofabrication, Vienna. Two types of e-beam resists were used for the cut exposure. Integration issues as well as overlay requirements and performance improvements necessary for this mix & match approach will be discussed.

  10. Beam dynamics studies in the driver LINAC pre-Stripper section of the RIA facility.

    SciTech Connect

    Lessner, E. S.; Ostroumov, P. N.

    2003-07-10

    The RIA facility driver linac consists of about 400 superconducting (SC) independently phased rf cavities. The linac is designed to accelerate simultaneously several-charge-state beams to generate as much as 400 kW of uranium beam power. The linac beam dynamics is most sensitive to the focusing and accelerating-structure parameters of the prestripper section, where the uranium beam is accelerated from 0.17 keV/u to 9.4 MeV/u. This section is designed to accept and accelerate 2 charge states (28 and 29) of uranium beam from an ECR ion source. The prestripper section must be designed to minimize the beam emittance distortion of this two-charge-state beam. In particular, the inter-cryostat spaces must be minimized and beam parameters near transitions of the accelerating and focusing lattices must be matched carefully. Several sources of possible effective emittance growth are considered in the design of the prestripper section and a tolerance budget is established. Numerical beam dynamics studies include realistic electric and magnetic 3-dimensional field distributions in the SC rf cavities and SC solenoids. Error effects in the longitudinal beam parameters are studied.

  11. Correlation study of a beam-position monitor and a photon-beam-position monitor in the PLS-II

    NASA Astrophysics Data System (ADS)

    Kim, Changbum; Shin, Seunghwan; Hwang, Ilmoon; Lee, Byung-Joon; Joo, Young-Do; Ha, Taekyun; Yoon, Jong Chel; Kim, Ghyung Hwa; Kim, Mungyung; Lee, Eun Hee; Kim, Ilyou; Huang, Jung-Yun

    2015-01-01

    The beam stability is one of the most important issues for the user service of the synchrotron radiation facility. After the upgrade of the Pohang Light Source (PLS-II), the electron-beam orbit is maintained within a root-mean-squred (rms) 1- μm range by using an orbit feedback system. However, that does not guarantee the radiation stability at the end of the beamline because unknown factors, such as focusing mirrors and double-crystal monocrometers, are present in the beamline. As a first step to solve this problem, photon-beam-position monitors (PBPMs) are installed in the front ends of the beamline to monitor the radiation stability. If the radiation is stable at the starting point of the beamline, we can move to the other components downstream that make the radiation unstable. In this paper, a correlation study will be presented between the beam-position monitor (BPM) and the PBPM. In addition, the effect of the orbit feedback system on the correlation will be described.

  12. 17 C Lifetime Measurements with the TRIPLEX Plunger and GRETINA

    NASA Astrophysics Data System (ADS)

    Smalley, Duane; Iwasaki, H.; Whitmore, K.; Morse, C.; Loelius, C.; Gade, A.; Weisshaar, D.; Bazin, D.; Langer, C.; Recchia, F.; Berryman, J.; Bader, V.; Stroberg, S. R.; Campbell, C.; Fallon, P.; Macchiavelli, A.; Wimmer, K.; Lemasson, A.; Parker, J.

    2013-10-01

    As nuclei approach the drip-line exotic features such as deformation and collectivity begin to manifest. Experimental observation of these features provide valuable inputs to test the validity of current theoretical models. Excited state lifetime measurements can be linked directly to the reduced transition probability allowing the inference of structure information. Recent lifetime measurements of the neutron rich 17C have been performed using the gamma-ray tracking array GRETINA and the newly designed TRIPLEX plunger at the NSCL. The TRIPLEX plunger allows multiple lifetimes, ranging from 1ps to 1ns, to be measured with a single setting. This provides a robust model independent methodology for determining excited state lifetimes through in-beam gamma-ray spectroscopy. Initial results of the lifetime measurements and the data analysis will be presented.

  13. Treatment of industrial effluents using electron beam accelerator and adsorption with activated carbon: a comparative study

    NASA Astrophysics Data System (ADS)

    de Oliveira Sampa, Maria Helena; Rela, Paulo Roberto; Casas, Alexandre Las; Mori, Manoel Nunes; Duarte, Celina Lopes

    2004-09-01

    This paper presents preliminary results of a study that compares the use of electron beam processing and activated carbon adsorption to clean up a standardized organic aqueous solution and a real industrial effluent. The electron beam treatment was performed in a batch system using the IPEN's Electron Beam Accelerators from Radiation Dynamics Inc., Dynamitron 37.5 kW. The granular activated carbon removal treatment was performed using charcoal made from wood "pinus". If the adequate irradiation dose is delivered to the organic pollutant, it is possible to conclude for the studied compounds that the Electron Beam Process is similar to the activated carbon process in organic removal efficiency.

  14. Beam loss studies in high-intensity heavy-ion linacs

    NASA Astrophysics Data System (ADS)

    Ostroumov, P. N.; Aseev, V. N.; Mustapha, B.

    2004-09-01

    The proposed Rare Isotope Accelerator (RIA) Facility, an innovative exotic-beam facility for the production of high-quality beams of short-lived isotopes, consists of a fully superconducting 1.4GV driver linac and a 140MV postaccelerator. To produce sufficient intensities of secondary beams the driver linac will provide 400kW primary beams of any ion from hydrogen to uranium. Because of the high intensity of the primary beams the beam losses must be minimized to avoid radioactivation of the accelerator equipment. To keep the power deposited by the particles lost on the accelerator structures below 1 W/m, the relative beam losses per unit length should be less than 10-5, especially along the high-energy section of the linac. A new beam dynamics simulation code TRACK has been developed and used for beam loss studies in the RIA driver linac. In the TRACK code, ions are tracked through the three-dimensional electromagnetic fields of every element of the linac starting from the electron cyclotron resonance (ECR) ion source to the production target. The simulation starts with a multicomponent dc ion beam extracted from the ECR. The space charge forces are included in the simulations. They are especially important in the front end of the driver linac. Beam losses are studied by tracking a large number of particles (up to 106) through the whole linac considering all sources of error such us element misalignments, rf field errors, and stripper thickness fluctuations. For each configuration of the linac, multiple sets of error values have been randomly generated and used in the calculations. The results are then combined to calculate important beam parameters, estimate beam losses, and characterize the corresponding linac configuration. To track a large number of particles for a comprehensive number of error sets (up to 500), the code TRACK was parallelized and run on the Jazz computer cluster at ANL.

  15. Efficiency and lifetime of carbon foils

    SciTech Connect

    Chou, W.; Kostin, M.; Tang, Z.; /Fermilab

    2006-11-01

    Charge-exchange injection by means of carbon foils is a widely used method in accelerators. This paper discusses two critical issues concerning the use of carbon foils: efficiency and lifetime. An energy scaling of stripping efficiency was suggested and compared with measurements. Several factors that determine the foil lifetime--energy deposition, heating, stress and buckling--were studied by using the simulation codes MARS and ANSYS.

  16. Design study of beam dynamics issues for 1 TeV next linear collider based upon the relativistic-klystron two-beam accelerator

    SciTech Connect

    Li, H.; Goffeney, N.; Henestroza, E.; Sessler, A.; Yu, S.; Houck, T.; Westenskow, G.

    1994-11-01

    A design study has recently been conducted for exploring the feasibility of a relativistic-klystron two-beam accelerator (RK-TBA) system as a rf power source for a 1 TeV linear collider. The author present, in this paper, the beam dynamics part of this study. They have achieved in their design study acceptable transverse and longitudinal beam stability properties for the resulting high efficiency and low cost RK-TBA.

  17. Design study of beam dynamics issues for a one TeV next linear collider based upon the relativistic klystron two-beam accelerator

    SciTech Connect

    Li, H.; Houck, T.; Goffeney, N.; Henestroza, E.; Sessler, A.; Westenskow, G.; Yu, S.

    1995-06-01

    A design study has recently been conducted for exploring the feasibility of a relativistic-klystron two-beam accelerator (RK-TBA) system as a rf power source for a 1 TeV linear collider. We present, in this paper, the beam dynamics part of this study. We have achieved in our design study acceptable transverse and longitudinal beam stability properties for the resulting high efficiency and low cost RK-TBA. {copyright} 1995 {ital American Institute of Physics}.

  18. A study of electron beam-induced conductivity in resists.

    PubMed

    Hwu, J J; Joy, D C

    1999-01-01

    The charging of polymeric resist materials during electron beam irradiation leads to significant problems during imaging and lithography processes. Charging occurs because of charge deposition in the polymer and charge generation/trapping due to formation of electron-hole pairs in the dielectric. The presence of such charge also results in the phenomena of electron beam-induced conductivity (EBIC). Electron beam-induced conductivity data have been obtained for three commercial e-beam resists under a variety of dose rate and temperature conditions. From the observed values of induced conductivity under varying conditions significant information about the generation of electron-hole pair and the transport of charge in the resist can be obtained. Three electron beam resists, EBR900, ZEP7000, and PBS are examined by an external bias method. The difference in resist chemistry is considered to play the role in the initial state EBIC behaviors among three resists even though the way that it affects the behaviors is not clear. A comparison of the power consumption comparison is proposed as a measure to give a preliminary estimate of the carrier concentration and carrier drift velocity differences among the resists. A simple single trap model with constant activation energy is proposed and provides good agreement with experiment.

  19. Fiber-Matrix Interface Studies on Electron Beam Cured Composites

    SciTech Connect

    Drazel, L.T.; Janke, C.J.; Yarborough, K.D.

    1999-05-23

    The recently completed Department of Energy (DOE) and industry sponsored Cooperative Research and Development Agreement (CRADA) entitled, ''Electron Beam Curing of Polymer Matrix Composites,'' determined that the interlaminar shear strength properties of the best electron beam cured IM7/epoxy composites were 19-28% lower than autoclave cured IM7/epoxy composites (i.e. IM7/977-2 and IM7/977-3). Low interlaminar shear strength is widely acknowledged as the key barrier to the successful acceptance and implementation of electron beam cured composites in the aircraft/aerospace industry. The objective of this work was to improve the interlaminar shear strength properties of electron beam cured composites by formulating and evaluating several different fiber sizings or coating materials. The researchers have recently achieved some promising results by having discovered that the application of epoxy-based, electron beam compatible sizings or coatings onto surface-treated, unsized IM7 carbon fibers improved the composite interlaminar shear strength properties by as much as 55% versus composites fabricated from surface-treated, unsized IM7 fibers. In addition, by applying these same epoxy-based sizings or coatings onto surface-treated, unsized IM7 fibers it was possible to achieve an 11% increase in the composite interlaminar shear strength compared to composites made from surface-treated, GP-sized IM7 fibers. Work is continuing in this area of research to further improve these properties.

  20. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    SciTech Connect

    Alferjani, M. B. S.; Samad, A. A. Abdul; Mohamad, Noridah; Elrawaff, Blkasem S.; Elzaroug, Omer

    2015-05-15

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

  1. Study on shear strengthening of RC continuous T-beams using different layers of CFRP strips

    NASA Astrophysics Data System (ADS)

    Alferjani, M. B. S.; Samad, A. A. Abdul; Elrawaff, Blkasem S.; Elzaroug, Omer; Mohamad, Noridah

    2015-05-01

    Carbon fiber reinforced polymer (CFRP) laminates are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. However, this paper presents the results of an experimental investigation for enhancing the shear capacity of reinforced concrete (RC) continuous T- beams using different layers of CFRP wrapping schemes. A total of three concrete beams were tested and various sheet configurations and layouts were studied to determine their effects on ultimate shear strength and shear capacity of the beams. One beam was kept as control beams, while other beams were strengthened with externally bonded CFRP strips with three side bonding and one or two layers of CFRP strips. From the test results, it was found that all schemes were found to be effective in enhancing the shear strength of RC beams. It was observed that the strength increases with the number of sheet layers provided the most effective strengthening for RC continuous T- beam. Beam strengthened using this scheme showed 23.21% increase in shear capacity as compared to the control beam. Two prediction models available in literature were used for computing the contribution of CFRP strips and compared with the experimental results.

  2. Charm lifetime measurements from TASSO

    SciTech Connect

    Forden, G.E.

    1987-10-09

    Recent measurements by TASSO of the lifetimes of charmed mesons is reviewed. The lifetime reported for the D/sub s/ meson utilizes the entire data sample collected. The lifetime of the neutral charmed meson, D/sup o/, is from a subsample of the total data set. Special emphases is given to the experimental procedures used.

  3. The Sprint to Lifetime Sports

    ERIC Educational Resources Information Center

    Ernst, Leonard

    1973-01-01

    Describes the trend in high school physical education programs toward lifetime sports, defined by the author as physical activities that will serve the interests of students for a lifetime. Included are a special report on program costs and a model of a performance-based lifetime sports program. (Author/DN)

  4. Maximizing TDRS Command Load Lifetime

    NASA Technical Reports Server (NTRS)

    Brown, Aaron J.

    2002-01-01

    The GNC software onboard ISS utilizes TORS command loads, and a simplistic model of TORS orbital motion to generate onboard TORS state vectors. Each TORS command load contains five "invariant" orbital elements which serve as inputs to the onboard propagation algorithm. These elements include semi-major axis, inclination, time of last ascending node crossing, right ascension of ascending node, and mean motion. Running parallel to the onboard software is the TORS Command Builder Tool application, located in the JSC Mission Control Center. The TORS Command Builder Tool is responsible for building the TORS command loads using a ground TORS state vector, mirroring the onboard propagation algorithm, and assessing the fidelity of current TORS command loads onboard ISS. The tool works by extracting a ground state vector at a given time from a current TORS ephemeris, and then calculating the corresponding "onboard" TORS state vector at the same time using the current onboard TORS command load. The tool then performs a comparison between these two vectors and displays the relative differences in the command builder tool GUI. If the RSS position difference between these two vectors exceeds the tolerable lim its, a new command load is built using the ground state vector and uplinked to ISS. A command load's lifetime is therefore defined as the time from when a command load is built to the time the RSS position difference exceeds the tolerable limit. From the outset of TORS command load operations (STS-98), command load lifetime was limited to approximately one week due to the simplicity of both the onboard propagation algorithm, and the algorithm used by the command builder tool to generate the invariant orbital elements. It was soon desired to extend command load lifetime in order to minimize potential risk due to frequent ISS commanding. Initial studies indicated that command load lifetime was most sensitive to changes in mean motion. Finding a suitable value for mean motion

  5. Electromagnetic and beam dynamics studies of a high current drift tube linac for LEHIPA

    NASA Astrophysics Data System (ADS)

    Roy, S.; Rao, S. V. L. S.; Pande, R.; Krishnagopal, S.; Singh, P.

    2014-06-01

    We have performed detailed electromagnetic and beam dynamics studies of a 352.21 MHz drift-tube linac (DTL) that will accelerate a 30 mA CW proton beam from 3 to 20 MeV. At such high currents space charge effects are important, and therefore the effect of linear as well as non-linear space charge has been studied (corresponding to uniform and Gaussian initial beam distributions), in order to avoid space charge instabilities. To validate the electromagnetic simulations, a 1.2 m long prototype of the DTL was fabricated. RF measurements performed on the prototype were in good agreement with the simulations. A detailed simulation study of beam halos was also performed, which showed that beyond a current of 10 mA, significant longitudinal beam halos are excited even for a perfectly matched beam, whereas for a mis-matched beam transverse beam halos are also excited. However, these do not lead to any beam loss within the DTL.

  6. Beam Dynamics Studies of Parallel-Bar Deflecting Cavities

    SciTech Connect

    S. Ahmed, G. Krafft, K. Detrick, S. Silva, J. Delayen, M. Spata ,M. Tiefenback, A. Hofler ,K. Beard

    2011-03-01

    We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and super-conducting. The compact size of these cavities as compared to conventional TM$_{110}$ type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of six 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and super-conducting structures show very small emittance dilution due to the vertical kick of the beam.

  7. Recent advances in crossed-beam studies of bimolecular reactions.

    PubMed

    Liu, Kopin

    2006-10-01

    A critical overview of the recent progress in crossed-beam reactive scattering is presented. This review is not intended to be an exhaustive nor a comprehensive one, but rather a critical assessment of what we have been learning about bimolecular reaction dynamics using crossed molecular beams since year 2000. Particular emphasis is placed on the information content encoded in the product angular distribution-the trait of a typical molecular beam scattering experiment-and how the information can help in answering fundamental questions about chemical reactivity. We will start with simple reactions by highlighting a few benchmark three-atom reactions, and then move on progressively to the more complex chemical systems and with more sophisticated types of measurements. Understanding what cause the experimental observations is more than computationally simulating the results. The give and take between experiment and theory in unraveling the physical picture of the underlying dynamics is illustrated throughout this review.

  8. Beam dynamics studies for transverse electromagnetic mode type rf deflectors

    DOE PAGES

    Ahmed, Shahid; Krafft, Geoffrey A.; Deitrick, Kirsten; De Silva, Subashini U.; Delayen, Jean R.; Spata, Mike; Tiefenback, Michael; Hofler, Alicia; Beard, Kevin

    2012-02-14

    We have performed three-dimensional simulations of beam dynamics for transverse electromagnetic mode (TEM) type rf deflectors: normal and superconducting. The compact size of these cavities as compared to the conventional TM110 type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of six 2-cell normal conducting cavities or a single cell superconducting structure is enough to produce the required vertical displacement at the target point. Both the normal and superconducting structures show very small emittance dilution due to the verticalmore » kick of the beam.« less

  9. Studies of beam halo formation in the 12GeV CEBAF design

    SciTech Connect

    Yves Roblin; Arne Freyberger

    2007-06-01

    Beam halo formation in the beam transport design for the Jefferson Lab 12GeV upgrade was investigated using 12GeV beam transport models as well as data from 6GeV CEBAF operations. Various halo sources were considered; these covered both nuclear interactions with beam gas as well as optics-related effects such as non linearities in the magnetic fields of the transport elements. Halo due to beam gas scattering was found to be less of a problem at 12GeV compared to the 6GeV machine. Halo due to non linear effects of magnetic elements was characterized as a function of beam orbit and functional forms of the distribution were derived. These functional forms were used as inputs in subsequent detector optimizations studies.

  10. Simulation Studies of Temperature Anisotropy Instability in Intense Charged Particle Beams for IBX Parameters

    NASA Astrophysics Data System (ADS)

    Startsev, E. A.; Davidson, R. C.; Qin, H.

    2003-10-01

    The Integrated Beam Experiment (IBX) is a proof-of-principal experiment for heavy ion fusion designed to test source-to-target beam physics using a single beam of K^+ ions of duration 0.2 - 1.5 μ s, accelerated to energies 5-10 MeV, and driver-scale normalized perviance in the range 10-5 -10-3. An important physics issue to be addressed by IBX is the effect of longitudinal-transverse coupling on the beam transport and focusibility of the driver. Our previous numerical and theoretical studies of intense charged particle beams with large temperature anisotropy [E. A. Startsev, R. C. Davidson and H. Qin, Phys. Plasmas 9, 3138, 2002] demonstrated that a fast, electrostatic, Harris-like instability may develop. This paper reports the results of recent simulations of the temperature anisotropy instability using the Beam Equilibrium Stability Transport (BEST) code for IBX parameters.

  11. Analysis of bending and buckling of pre-twisted beams: A bioinspired study

    NASA Astrophysics Data System (ADS)

    Zhao, Zi-Long; Zhao, Hong-Ping; Chang, Zheng; Feng, Xi-Qiao

    2014-08-01

    Twisting chirality is widely observed in artificial and natural materials and structures at different length scales. In this paper, we theoretically investigate the effect of twisting chiral morphology on the mechanical properties of elastic beams by using the Timoshenko beam model. Particular attention is paid to the transverse bending and axial buckling of a pre-twisted rectangular beam. The analytical solution is first derived for the deflection of a clamped-free beam under a uniformly or periodically distributed transverse force. The critical buckling condition of the beam subjected to its self-weight and an axial compressive force is further solved. The results show that the twisting morphology can significantly improve the resistance of beams to both transverse bending and axial buckling. This study helps understand some phenomena associated with twisting chirality in nature and provides inspirations for the design of novel devices and structures.

  12. Analytic and numerical studies of the modified betatron. [Kiloamp beams

    SciTech Connect

    Hughes, T.P.; Campbell, M.M.; Godfrey, B.B.

    1983-08-01

    The modified betatron concept has been proposed as a means of accelerating high current (kiloamp) electron beams to high energy. This device employs a toroidal magnetic field to overcome the space-charge limit on the current in a conventional betatron at low energy. In this paper, the authors look at the injection, equilibrium and stability of the modified betatron. The main emphasis is on stability. An analytic dispersion relation is derived using a cold-fluid model of the beam. The results are compared to three-dimensional simulations performed with the electromagnetic PIC code IVORY. The nonlinear development of the negative mass instability is followed in the simulations.

  13. High transformer ratio drive beams for wakefield accelerator studies

    SciTech Connect

    England, R. J.; Ng, C.-K.; Frederico, J.; Hogan, M. J.; Litos, M.; Muggli, P.; Joshi, C.; An, W.; Andonian, G.; Mori, W.; Lu, W.

    2012-12-21

    For wakefield based acceleration schemes, use of an asymmetric (or linearly ramped) drive bunch current profile has been predicted to enhance the transformer ratio and generate large accelerating wakes. We discuss plans and initial results for producing such bunches using the 20 to 23 GeV electron beam at the FACET facility at SLAC National Accelerator Laboratory and sending them through plasmas and dielectric tubes to generate transformer ratios greater than 2 (the limit for symmetric bunches). The scheme proposed utilizes the final FACET chicane compressor and transverse collimation to shape the longitudinal phase space of the beam.

  14. B Lifetimes and Mixing

    SciTech Connect

    Evans, Harold G.; /Indiana U.

    2009-05-01

    The Tevatron experiments, CDF and D0, have produced a wealth of new B-physics results since the start of Run II in 2001. We've observed new B-hadrons, seen new effects, and increased many-fold the precision with which we know the properties of b-quark systems. In these proceedings, we will discuss two of the most fruitful areas in the Tevatron B-physics program: lifetimes and mixing. We'll examine the experimental issues driving these analyses, present a summary of the latest results, and discuss prospects for the future.

  15. Simulation study of accelerator based quasi-mono-energetic epithermal neutron beams for BNCT.

    PubMed

    Adib, M; Habib, N; Bashter, I I; El-Mesiry, M S; Mansy, M S

    2016-01-01

    Filtered neutron techniques were applied to produce quasi-mono-energetic neutron beams in the energy range of 1.5-7.5 keV at the accelerator port using the generated neutron spectrum from a Li (p, n) Be reaction. A simulation study was performed to characterize the filter components and transmitted beam lines. The feature of the filtered beams is detailed in terms of optimal thickness of the primary and additive components. A computer code named "QMNB-AS" was developed to carry out the required calculations. The filtered neutron beams had high purity and intensity with low contamination from the accompanying thermal, fast neutrons and γ-rays.

  16. Measurement of the Ds lifetime

    NASA Astrophysics Data System (ADS)

    Fermilab E791 Collaboration; Aitala, E. M.; Amato, S.; Anjos, J. C.; Appel, J. A.; Ashery, D.; Banerjee, S.; Bediaga, I.; Blaylock, G.; Bracker, S. B.; Burchat, P. R.; Burnstein, R. A.; Carter, T.; Carvalho, H. S.; Copty, N. K.; Cremaldi, L. M.; Darling, C.; Denisenko, K.; Fernandez, A.; Fox, G. F.; Gagnon, P.; Gobel, C.; Gounder, K.; Halling, A. M.; Herrera, G.; Hurvits, G.; James, C.; Kasper, P. A.; Kwan, S.; Langs, D. C.; Leslie, J.; Lundberg, B.; Maytal-Beck, S.; Meadows, B.; de Mello Neto, J. R. T.; Mihalcea, D.; Milburn, R. H.; de Miranda, J. M.; Napier, A.; Nguyen, A.; D'Oliveira, A. B.; O'Shaughnessy, K.; Peng, K. C.; Perera, L. P.; Purohit, M. V.; Quinn, B.; Radeztsky, S.; Rafatian, A.; Reay, N. W.; Reidy, J. J.; Dos Reis, A. C.; Rubin, H. A.; Sanders, D. A.; Santha, A. K. S.; Santoro, A. F. S.; Schwartz, A. J.; Sheaff, M.; Sidwell, R. A.; Slaughter, A. J.; Sokoloff, M. D.; Solano, J.; Stanton, N. R.; Stefanski, R. J.; Stenson, K.; Summers, D. J.; Takach, S.; Thorne, K.; Tripathi, A. K.; Watanabe, S.; Weiss-Babai, R.; Wiener, J.; Witchey, N.; Wolin, E.; Yang, S. M.; Yi, D.; Yoshida, S.; Zaliznyak, R.; Zhang, C.

    1999-01-01

    We report the results of a precise measurement of the Ds meson lifetime based on 1662+/-56 fully reconstructed Ds-->φπ decays, from the charm hadroproduction experiment E791 at Fermilab. Using an unbinned maximum likelihood fit, we measure the Ds lifetime to be 0.518+/-0.014+/-0.007 ps. The ratio of the measured Ds lifetime to the world average D0 lifetime [1] is 1.25+/-0.04. This result differs from unity by six standard deviations, indicating significantly different lifetimes for the Ds and the D0.

  17. RDM lifetime measurements in 107Cd

    SciTech Connect

    Andgren, K.; Ashley, S.F.; Regan, P.H.; McCutchan, E.A.; Zamfir,N.V.; Amon, L.; Cakirli, R.B.; Casten, R.F.; Clark, R.M.; Gurdal, G.; Keyes, K.L.; Meyer, D.A.; Erduran, M.N.; Papenberg, A.; Pietralla, N.; Plettner, C.; Rainovski, G.; Ribas, R.V.; Thomas, N.J.; Vinson, J.; Warner, D.D.; Werner, V.; Williams, E.

    2005-03-18

    Lifetimes for decays linking near-yrast states in {sup 107}Cd have been measured using the recoil distance method (RDM). The nucleus of interest was populated via the {sup 98}Mo({sup 12}C,3n){sup 107}Cd fusion-evaporation reaction at an incident beam energy of 60 MeV. From the measured lifetimes, transition probabilities have been deduced and compared with the theoretical B(E2) values for limiting cases of harmonic vibrational and axially deformed rotational systems. Our initial results suggest a rotor-like behavior for the structure based on the unnatural-parity, h{sub 11/2} orbital in {sup 107}Cd, providing further evidence for the role of this 'shape-polarizing' orbital in stabilizing the nuclear deformation in the A {approx} 100 transitional region.

  18. An irradiation facility with a horizontal beam for radiobiological studies.

    PubMed

    Czub, J; Banas, D; Braziewicz, J; Choinski, J; Jaskóla, M; Korman, A; Szeflinski, Z; Wójcik, A

    2006-01-01

    A facility with a horizontal beam for radiobiological experiments with heavy ions has been designed and constructed at the Heavy Ion Laboratory in Warsaw University. The facility is optimal to investigate the radiobiological effects of charged heavy particles on a cellular or molecular level as in the region of the Bragg peak.

  19. Experimental and numerical study of high intensity argon cluster beams

    SciTech Connect

    Korobeishchikov, N. G.; Kalyada, V. V.; Shmakov, A. A.; Zarvin, A. E.; Skovorodko, P. A.

    2014-12-09

    Experimental and numerical investigations of expansion of argon with homogeneous condensation in supersonic conical nozzle and in free jet behind it were carried out. Optimal parameters (stagnation pressure, nozzle-skimmer distance) for the formation of cluster beam with maximum intensity were determined. Two available models for nonequilibrium nucleation were tested. The numerical results are in satisfactory agreement with the measured data.

  20. Beam studies at the SPEAR3 synchrotron using a digital optical mask

    NASA Astrophysics Data System (ADS)

    Zhang, H. D.; Fiorito, R. B.; Corbett, J.; Shkvarunets, A. G.; Tian, K.; Fisher, A.

    2016-05-01

    The 3GeV SPEAR3 synchrotron light source operates in top-up injection mode with up to 500 mA circulating in the storage ring (equivalently 392 nC). Each injection pulse contains 40-80 pC producing a contrast ratio between total stored charge and injected charge of about 6500:1. In order to study transient injected beam dynamics during user operations, it is desirable to optically image the injected pulse in the presence of the bright stored beam. In the present work this is done by imaging the visible component of the synchrotron radiation onto a digital micro-mirror-array device (DMD), which is then used as an optical mask to block out light from the bright central core of the stored beam. The physical masking, together with an asynchronously-gated, ICCD imaging camera, makes it possible to observe the weak injected beam component on a turn-by-turn basis. The DMD optical masking system works similar to a classical solar coronagraph but has some distinct practical advantages: i.e. rapid adaption to changes in the shape of the stored beam, a high extinction ratio for unwanted light and minimum scattering from the primary beam into the secondary optics. In this paper we describe the DMD masking method, features of the high dynamic range point spread function for the SPEAR3 optical beam line and measurements of the injected beam in the presence of the stored beam.

  1. Lifetime characteristics of ohmic MEMS switches

    NASA Astrophysics Data System (ADS)

    Maciel, John; Majumder, Sumit; Morrison, Richard; Lampen, James

    2004-01-01

    In the future, MEMS switches will be important building blocks for designing phase shifters, smart antennas, cell phones and switched filters for military and commercial markets, to name a few. Low power consumption, large ratio of off-impedance to on-impedance and the ability to be integrated with other electronics makes MEMS switches an attractive alternative to other mechanical and solid-state switches. Radant MEMS has developed an electrostatically actuated broadband ohmic microswitch that has applications from DC through the microwave region. The microswitch is a 3-terminal device based on a cantilever beam and is fabricated using an all-metal, surface micromachining process. It operates in a hermetic environment obtained through a wafer-bonding process. We have developed PC-based test stations to cycle switches and measure lifetime under DC and RF loads. Best-case lifetimes of 1011 cycles have been achieved in T0-8 cans (a precursor to our wafer level cap) while greater than 1010 cycles have been achieved in the wafer level package. Several switches from different lots have been operated to 1010 cycles. Current typical lifetime exceeds 2 billion cycles and is limited by contact stiction resulting in stuck-closed failures. Stuck-closed failures can be intermittent with a large number of switches continuing to operate with occasional sticks beyond several billion cycles. To eliminate contact stiction, we need to better control the ambient gas composition in the die cavity. We expect lifetime to improve as we continue to develop and optimize the wafer capping process. We present DC and RF lifetime data under varying conditions.

  2. Lifetime characteristics of ohmic MEMS switches

    NASA Astrophysics Data System (ADS)

    Maciel, John; Majumder, Sumit; Morrison, Richard; Lampen, James

    2003-12-01

    In the future, MEMS switches will be important building blocks for designing phase shifters, smart antennas, cell phones and switched filters for military and commercial markets, to name a few. Low power consumption, large ratio of off-impedance to on-impedance and the ability to be integrated with other electronics makes MEMS switches an attractive alternative to other mechanical and solid-state switches. Radant MEMS has developed an electrostatically actuated broadband ohmic microswitch that has applications from DC through the microwave region. The microswitch is a 3-terminal device based on a cantilever beam and is fabricated using an all-metal, surface micromachining process. It operates in a hermetic environment obtained through a wafer-bonding process. We have developed PC-based test stations to cycle switches and measure lifetime under DC and RF loads. Best-case lifetimes of 1011 cycles have been achieved in T0-8 cans (a precursor to our wafer level cap) while greater than 1010 cycles have been achieved in the wafer level package. Several switches from different lots have been operated to 1010 cycles. Current typical lifetime exceeds 2 billion cycles and is limited by contact stiction resulting in stuck-closed failures. Stuck-closed failures can be intermittent with a large number of switches continuing to operate with occasional sticks beyond several billion cycles. To eliminate contact stiction, we need to better control the ambient gas composition in the die cavity. We expect lifetime to improve as we continue to develop and optimize the wafer capping process. We present DC and RF lifetime data under varying conditions.

  3. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Petzold, A.; Hasselbach, J.; Lauer, P.; Baumann, R.; Franke, K.; Gurk, C.; Schlager, H.; Weingartner, E.

    2007-10-01

    Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel)-1 by number for non-volatile particles and 174±43 mg (kg fuel)-1 by mass for Black Carbon (BC). Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dp<0.3 μm, showing a bi-modal structure. The combustion particle mode is centred at modal diameters of 0.05 μm for raw emissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

  4. Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Petzold, A.; Hasselbach, J.; Lauer, P.; Baumann, R.; Franke, K.; Gurk, C.; Schlager, H.; Weingartner, E.

    2008-05-01

    Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel)-1 by number for non-volatile particles and 174±43 mg (kg fuel)-1 by mass for Black Carbon (BC). Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dp<0.3 μm, showing a bi-modal structure. The combustion particle mode is centred at modal diameters of 0.05 μm for raw emissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

  5. COMPUTATIONAL BEAM DYNAMICS STUDIES FOR IMPROVING THE RING INJECTION AND EXTRACTION SYSTEMS IN SNS

    SciTech Connect

    Holmes, Jeffrey A; Cousineau, Sarah M; Plum, Michael A; Wang, Jian-Guang

    2008-01-01

    The ring injection and extraction systems must function as designed in order for the Spallation Neutron Source (SNS) to achieve its specified performance. In commissioning and early operations we have encountered problems that have been traced to these systems. We experienced high beam losses in and around the injection dump, the rectification of which has necessitated ongoing study and development by a multidisciplinary team. Results already include a number of enhancements of existing features and the addition of new elements and diagnostics. The problem in the extraction region stems from tilted beam distributions observed in the ring-to-target beam transport line (RTBT) and on the target, thus complicating the control of the beam-on-target distribution. This indicates the inadvertent introduction of x-y beam coupling somewhere upstream of the RTBT. The present paper describes computational studies, using the ORBIT Code, addressed at the detailed understanding and solution of these problems.

  6. Metric for the measurement of the quality of complex beams: a theoretical study.

    PubMed

    Kaim, Sergiy; Lumeau, Julien; Smirnov, Vadim; Zeldovich, Boris; Glebov, Leonid

    2015-04-01

    We present a theoretical study of various definitions of laser beam width in a given cross section. Quality of the beam is characterized by dimensionless beam propagation products (BPPs) Δx·Δθ(x)/λ, which are different for the 21 definitions presented, but are close to 1. Six particular beams are studied in detail. In the process, we had to review the properties for the Fourier transform of various modifications and the relationships between them: physical Fourier transform (PFT), mathematical Fourier transform (MFT), and discrete Fourier transform (DFT). We found an axially symmetric self-MFT function, which may be useful for descriptions of diffraction-quality beams. In the appendices, we illustrate the thesis "the Fourier transform lives on the singularities of the original." PMID:26366763

  7. Electron-beam studies of Schottky-barrier detector surfaces

    NASA Technical Reports Server (NTRS)

    Peckerar, M. C.

    1973-01-01

    Review of the surface anomalies occurring in Schottky-barrier particle detectors identifiable by means of an electron beam technique employed by Czaja (1965) for analyzing defects in diode structures. The technique is shown to make possible the detection and identification of the following anomalies: (1) chemical contamination of the detector surface; (2) mechanical damage of the wafer substrates; (3) damage introduced in semiconductor surface preparation; (4) radiation damage; and (5) defective surface metallization.

  8. Native cation vacancies in Si-doped AlGaN studied by monoenergetic positron beams

    NASA Astrophysics Data System (ADS)

    Uedono, A.; Tenjinbayashi, K.; Tsutsui, T.; Shimahara, Y.; Miyake, H.; Hiramatsu, K.; Oshima, N.; Suzuki, R.; Ishibashi, S.

    2012-01-01

    Native defects in Si-doped AlGaN grown by metalorganic vapor phase epitaxy were probed by monoenergetic positron beams. Doppler broadening spectra of the annihilation radiation and positron lifetimes were measured, and these were compared with results obtained using first-principles calculation. For Si-doped AlxGa1-xN (4 × 1017 Si/cm3), the vacancy-type defects were introduced at above x = 0.54, and this was attributed to the transition of the growth mode to the Stranski-Krastanov mechanism from the Frank-van der Merwe mechanism. For Si-doped Al0.6Ga0.4N, the vacancy concentration increased with increasing Si concentration, and the major defect species was identified as Al vacancies. A clear correlation between the suppression of cathodoluminescence and the defect concentration was obtained, suggesting the cation vacancies act as nonradiative centers in AlGaN.

  9. A review of studies on ion thruster beam and charge-exchange plasmas

    NASA Technical Reports Server (NTRS)

    Carruth, M. R., Jr.

    1982-01-01

    Various experimental and analytical studies of the primary beam and charge-exchange plasmas of ion thrusters are reviewed. The history of plasma beam research is recounted, emphasizing experiments on beam neutralization, expansion of the beam, and determination of beam parameters such as electron temperature, plasma density, and plasma potential. The development of modern electron bombardment ion thrusters is treated, detailing experimental results. Studies on charge-exchange plasma are discussed, showing results such as the relationship between neutralizer emission current and plasma beam potential, ion energies as a function of neutralizer bias, charge-exchange ion current collected by an axially moving Faraday cup-RPA for 8-cm and 30-cm ion thrusters, beam density and potential data from a 15-cm ion thruster, and charge-exchange ion flow around a 30-cm thruster. A 20-cm thruster electrical configuration is depicted and facility effects are discussed. Finally, plasma modeling is covered in detail for plasma beam and charge-exchange plasma.

  10. The Lifetime Experiences of Being Labeled "Gifted": Case Studies of Adults Who Participated in a 1959 Public School Gifted Program

    ERIC Educational Resources Information Center

    Beckerle, John R.

    2013-01-01

    The purpose of the study was to explore the current perceptions of adults who were enrolled in the gifted program of the St. Louis Public Schools in the fall of 1959 or spring of 1960. At this time in history the Cold War was a reality and the U.S. enacted the National Defense Education Act (NDEA) to find talented young people and give them the…

  11. Study on the lifetime of Mo/Si multilayer optics with pulsed EUV-source at the ETS

    NASA Astrophysics Data System (ADS)

    Schürmann, Mark; Yulin, Sergiy; Nesterenko, Viatcheslav; Feigl, Torsten; Kaiser, Norbert; Tkachenko, Boris; Schürmann, Max C.

    2011-06-01

    As EUV lithography is on its way into production stage, studies of optics contamination and cleaning under realistic conditions become more and more important. Due to this fact an Exposure Test Stand (ETS) has been constructed at XTREME technologies GmbH in collaboration with Fraunhofer IOF and with financial support of Intel Corporation. This test stand is equipped with a pulsed DPP source and allows for the simultaneous exposure of several samples. In the standard set-up four samples with an exposed area larger than 35 mm2 per sample can be exposed at a homogeneous intensity of 0.25 mW/mm2. A recent update of the ETS allows for simultaneous exposures of two samples with intensities up to 1.0 mW/mm2. The first application of this alternative set-up was a comparative study of carbon contamination rates induced by EUV radiation from the pulsed source with contamination rates induced by quasicontinuous synchrotron radiation. A modified gas-inlet system allows for the introduction of a second gas to the exposure chamber. This possibility was applied to investigate the efficiency of EUV-induced cleaning with different gas mixtures. In particular the enhancement of EUV-induced cleaning by addition of a second gas to the cleaning gas was studied.

  12. Studies on Nuclear Astrophysics and Exotic Structure at the Low-Energy RI Beam Facility CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Kahl, D.; Hayakawa, S.; Sakaguchi, Y.; Nakao, T.; Wakabayashi, Y.; Hashimoto, T.; Teranishi, T.; Kubono, S.; Cherubini, S.; Mazzocco, M.; Signorini, C.; Gulino, M.; Di Pietro, A.; Figuera, P.; La Cognata, M.; Lattuada, M.; Spitaleri, C.; Torresi, D.; Lee, P. S.; Lee, C. S.; Komatsubara, T.; Iwasa, N.; Okoda, Y.; Pierroutsakou, D.; Parascandolo, C.; La Commara, M.; Strano, E.; Boiano, C.; Boiano, A.; Manea, C.; Sánchez-Benítez, A. M.; Miyatake, H.; Watanabe, Y. X.; Ishiyama, H.; Jeong, S. C.; Imai, N.; Hirayama, Y.; Kimura, S.; Mukai, M.; Kim, Y. H.; Lin, C. J.; Jia, H. M.; Yan, L.; Yang, Y. Y.; Kawabata, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. N.

    Studies on nuclear astrophysics, resonant structure, and nuclear reaction are going on at CRIB (CNS Radioactive Ion Beam separator), a low-energy RI beam separator operated by Center for Nuclear Study (CNS), the University of Tokyo. Two major methods used at CRIB to study nuclear reactions of astrophysical relevance are the resonant scattering, and direct measurements of (α,p) reactions using a thick-gas target. Several experiments for decay measurements and reaction mechanism are also performed using low-energy RI beams at CRIB. Some of the results from recent experiments at CRIB are discussed.

  13. Theoretical and experimental study on the transverse vibration properties of an axially moving nested cantilever beam

    NASA Astrophysics Data System (ADS)

    Duan, Ying-Chang; Wang, Jian-Ping; Wang, Jing-Quan; Liu, Ya-Wen; Shao, Fei

    2014-06-01

    An axially moving nested cantilever beam is a type of time-varying nonlinear system that can be regarded as a cantilever stepped beam. The transverse vibration equation for the axially moving nested cantilever beam with a tip mass is derived by D'Alembert's principle, and the modified Galerkin's method is used to solve the partial differential equation. The theoretical model is modified by adjusting the theoretical beam length with the measured results of its first-order vibration frequencies under various beam lengths. It is determined that the length correction value of the second segment of the nested beam increases as the structural length increases, but the corresponding increase in the amplitude becomes smaller. The first-order decay coefficients are identified by the logarithmic decrement method, and the decay coefficient of the beam decreases with an increase in the cantilever length. The calculated responses of the modified model agree well with the experimental results, which verifies the correctness of the proposed calculation model and indicates the effectiveness of the methods of length correction and damping determination. Further studies on non-damping free vibration properties of the axially moving nested cantilever beam during extension and retraction are investigated in the present paper. Furthermore, the extension movement of the beam leads the vibration displacement to increase gradually, and the instantaneous vibration frequency and the vibration speed decrease constantly. Moreover, as the total mechanical energy becomes smaller, the extension movement of the nested beam remains stable. The characteristics for the retraction movement of the beam are the reverse.

  14. Fluorescence Lifetime Imaging of Apoptosis

    PubMed Central

    Xiao, Annie; Gibbons, Anne E.; Luker, Kathryn E.; Luker, Gary D.

    2015-01-01

    Genetically-encoded fluorescence resonance energy transfer (FRET) reporters are powerful tools to analyze cell signaling and function at single cell resolution in standard two-dimensional cell cultures, but these reporters rarely have been applied to three-dimensional environments. FRET interactions between donor and acceptor molecules typically are determined by changes in relative fluorescence intensities, but wavelength-dependent differences in absorption of light complicate this analysis method in three-dimensional settings. Here we report fluorescence lifetime imaging microscopy (FLIM) with phasor analysis, a method that displays fluorescence lifetimes on a pixel-wise basis in real time, to quantify apoptosis in breast cancer cells stably expressing a genetically encoded FRET reporter. This microscopic imaging technology allowed us to identify treatment-induced apoptosis in single breast cancer cells in environments ranging from two-dimensional cell culture, spheroids with cancer and bone marrow stromal cells, and living mice with orthotopic human breast cancer xenografts. Using this imaging strategy, we showed that combined metabolic therapy targeting glycolysis and glutamine pathways significantly reduced overall breast cancer metabolism and induced apoptosis. We also determined that distinct subpopulations of bone marrow stromal cells control resistance of breast cancer cells to chemotherapy, suggesting heterogeneity of treatment responses of malignant cells in different bone marrow niches. Overall, this study establishes FLIM with phasor analysis as an imaging tool for apoptosis in cell-based assays and living mice, enabling real-time, cellular-level assessment of treatment efficacy and heterogeneity. PMID:26771007

  15. Nonlinear beam dynamics studies at Indiana University. Final report, August 1, 1993--July 31, 1997

    SciTech Connect

    Lee, S.Y.

    1998-03-31

    During the three-year funding period the author`s achievements can be summarized as follows: (1) The author has systematically studied the effect of phase modulation on bunch distribution. (2) The author has found that a frequently observed proton beam instability when the velocity of cooling electrons differs from that of protons is due to Hopf bifurcation. The equilibrium proton beam distribution becomes a limiting cycle attractor. This technique can be used to measure the temperature of cooling electrons. (3) The author has studied mechanisms of controlled bunch dilution. Evolution of beam bunch profile is measured while the beam is perturbed by the modulation of a secondary rf system. The experimental data reveal that mean square bunch length {sigma}{sup 2}(t) exhibits two characteristic time scales. He finds that overlapping parametric resonances plays an important role in beam diffusion. (4) He has studied the effects of global chaos on the halo formation of space charge dominated beams. He has analyzed the halo produced by a modulating mismatched space charge dominated beam in a uniform focusing channel. He found that the halo formation is determined by a single scaling parameter, the space charge perveance parameter divided by the phase advance per unit length. The condition of global chaos can thus be predicted. In June 1994, Indiana University has served as the host of the USPAS (United States Particle Accelerator School). In July 1994, IUCF has also served as the host site of the workshop on the future direction of hadron facilities. In October 1994, the author organized a successful workshop on space charge dominated beams and application of high brightness beams. During this period of this funding, he has had many visitors from SSC, SLAC, Fermilab, and Brookhaven National Laboratory. He has carried out many nonlinear beam dynamics experiments at the IUCF Cooler Ring. He has published about 30 refereed journal papers related to this project. These

  16. Hydrogen Bond Lifetimes and Energetics for Solute-Solvent Complexes Studied with 2D-IR Vibrational Echo Spectroscopy

    PubMed Central

    Zheng, Junrong; Fayer, Michael D.

    2008-01-01

    Weak π hydrogen bonded solute-solvent complexes are studied with ultrafast two dimensional infrared (2D-IR) vibrational echo chemical exchange spectroscopy, temperature dependent IR absorption spectroscopy, and density functional theory calculations. Eight solute-solvent complexes composed of a number of phenol derivatives and various benzene derivatives are investigated. The complexes are formed between the phenol derivative (solute) in a mixed solvent of the benzene derivative and CCl4. The time dependence of the 2D-IR vibrational echo spectra of the phenol hydroxyl stretch is used to directly determine the dissociation and formation rates of the hydrogen bonded complexes. The dissociation rates of the weak hydrogen bonds are found to be strongly correlated with their formation enthalpies. The correlation can be described with an equation similar to the Arrhenius equation. The results are discussed in terms of transition state theory. PMID:17373792

  17. Positron Annihilation Lifetime Spectroscopy Study of Neutron Irradiated High Temperature Superconductors YBa2Cu3O7-δ for Application in Fusion Facilities

    NASA Astrophysics Data System (ADS)

    Veterníková, J.; Chudý, M.; Slugeň, V.; Eisterer, M.; Weber, H. W.; Sojak, S.; Petriska, M.; Hinca, R.; Degmová, J.; Sabelová, V.

    2012-02-01

    This study focuses on the crystallographic defects introduced by neutron irradiation and the resulting changes of the superconducting properties in the high temperature superconductor YBa2Cu3O7-δ. This material is considered to be most promising for magnet systems in future fusion reactors. Two different bulk samples, pure non-doped YBa2Cu3O7-δ (YBCO) and multi-seed YBa2Cu3O7-δ doped by platinum (MS2F) were studied prior to and after irradiation in the TRIGA MARK II reactor in Vienna. Neutron irradiation is responsible for a significant enhancement of the critical current densities as well as for a reduction in critical temperature. The accumulation of small open volume defects (<0.5 nm) partially causes those changes. These defects were studied by positron annihilation lifetime spectroscopy at room temperature. A high concentration of Cu-O di-vacancies was found in both samples, which increased with neutron fluence. The defect concentration was significantly reduced after a heat treatment.

  18. Beam tracking strategies for studies of kinetic scales in the solar wind with THOR-CSW

    NASA Astrophysics Data System (ADS)

    De Keyser, Johan; Lavraud, Benoit; Neefs, Eddy; Berkenbosch, Sophie; Anciaux, Michel; Maggiolo, Romain

    2016-04-01

    Modern plasma spectrometers for monitoring the solar wind attempt to intelligently track the energy and direction of the solar wind beam in order to obtain solar wind velocity distributions more efficiently. Such beam tracking strategies offer some benefits, but also have their limitations and drawbacks. Benefits include an improved resolution and/or a faster velocity distribution function acquisition time. Limitations are due to instrument characteristics that tend to be optimized for a particular range of particle energies and arrival directions. A drawback is the risk to miss an important part of the velocity distribution or to lose track of the beam altogether. A comparison is presented of different beam tracking strategies under consideration for the THOR-CSW instrument in order to highlight a number of design decisions and their impact on the acquired velocity distributions. The gain offered by beam tracking in terms of increased time resolution turns out to be essential for studies of solar wind physics at kinetic scales.

  19. Study of nonlinear interaction between bunched beam and intermediate cavities in a relativistic klystron amplifier

    SciTech Connect

    Wu, Y.; Xu, Z.; Li, Z. H.; Tang, C. X.

    2012-07-15

    In intermediate cavities of a relativistic klystron amplifier (RKA) driven by intense relativistic electron beam, the equivalent circuit model, which is widely adopted to investigate the interaction between bunched beam and the intermediate cavity in a conventional klystron design, is invalid due to the high gap voltage and the nonlinear beam loading in a RKA. According to Maxwell equations and Lorentz equation, the self-consistent equations for beam-wave interaction in the intermediate cavity are introduced to study the nonlinear interaction between bunched beam and the intermediate cavity in a RKA. Based on the equations, the effects of modulation depth and modulation frequency of the beam on the gap voltage amplitude and its phase are obtained. It is shown that the gap voltage is significantly lower than that estimated by the equivalent circuit model when the beam modulation is high. And the bandwidth becomes wider as the beam modulation depth increases. An S-band high gain relativistic klystron amplifier is designed based on the result. And the corresponding experiment is carried out on the linear transformer driver accelerator. The peak output power has achieved 1.2 GW with an efficiency of 28.6% and a gain of 46 dB in the corresponding experiment.

  20. Neurocognitive Outcomes Decades After Treatment for Childhood Acute Lymphoblastic Leukemia: A Report From the St Jude Lifetime Cohort Study

    PubMed Central

    Krull, Kevin R.; Brinkman, Tara M.; Li, Chenghong; Armstrong, Gregory T.; Ness, Kirsten K.; Srivastava, Deo Kumar; Gurney, James G.; Kimberg, Cara; Krasin, Matthew J.; Pui, Ching-Hon; Robison, Leslie L.; Hudson, Melissa M.

    2013-01-01

    Purpose To determine rates, patterns, and predictors of neurocognitive impairment in adults decades after treatment for childhood acute lymphoblastic leukemia (ALL). Patients and Methods Survivors of childhood ALL treated at St Jude Children's Research Hospital who were still alive at 10 or more years after diagnosis and were age ≥ 18 years were recruited for neurocognitive testing. In all, 1,014 survivors were eligible, 738 (72.8%) agreed to participate, and 567 (76.8%) of these were evaluated. Mean age was 33 years; mean time since diagnosis was 26 years. Medical record abstraction was performed for data on doses of cranial radiation therapy (CRT) and cumulative chemotherapy. Multivariable modeling was conducted and glmulti package was used to select the best model with minimum Akaike information criterion. Results Impairment rates across neurocognitive domains ranged from 28.6% to 58.9%, and those treated with chemotherapy only demonstrated increased impairment in all domains (all P values < .006). In survivors who received no CRT, dexamethasone was associated with impaired attention (relative risk [RR], 2.12; 95% CI, 1.11 to 4.03) and executive function (RR, 2.42; 95% CI, 1.20 to 4.91). The impact of CRT was dependent on young age at diagnosis for intelligence, academic, and memory functions. Risk for executive function problems increased with survival time in a CRT dose-dependent fashion. In all survivors, self-reported behavior problems increased by 5% (RR, 1.05; 95% CI, 1.01 to 1.09) with each year from diagnosis. Impairment was associated with reduced educational attainment and unemployment. Conclusion This study demonstrates persistent and significant neurocognitive impairment in adult survivors of childhood ALL and warrants ongoing monitoring of brain health to facilitate successful adult development and to detect early onset of decline as survivors mature. PMID:24190124

  1. RESULTS OF THE NASA SPACE RADIATION LABORATORY BEAM STUDIES PROGRAM AT BNL.

    SciTech Connect

    BROWN,K.A.AHRENS,L.BEUTTENMULLER,R.H.ET AL.

    2004-07-05

    The NASA Space Radiation Laboratory (NSRL) was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL makes use of heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. The purpose of the NSRL Beam Studies Program is to develop a clear understanding of the beams delivered to the facility, to fully characterize those beams, and to develop new capabilities in the interest of understanding the radiation environment in space. In this report we will describe the first results from this program.

  2. Long path-length experimental studies of longitudinal phenomena in intense beams

    NASA Astrophysics Data System (ADS)

    Beaudoin, B. L.; Haber, I.; Kishek, R. A.; Bernal, S.; Koeth, T. W.

    2016-05-01

    Intense charged particle beams are nonneutral plasmas as they can support a host of plasma waves and instabilities. The longitudinal physics, for a long beam, can often be reasonably described by a 1-D cold-fluid model with a geometry factor to account for the transverse effects. The plasma physics of such beams has been extensively studied theoretically and computationally for decades, but until recently, the only experimental measurements were carried out on relatively short linacs. This work reviews experimental studies over the past five years on the University of Maryland Electron Ring, investigating longitudinal phenomena over time scales of thousands of plasma periods, illustrating good agreement with simulations.

  3. Beam dynamics studies and parametric characterization of a standing wave electron linac

    NASA Astrophysics Data System (ADS)

    Dash, R.; Mondal, J.; Sharma, A.; Mittal, K. C.

    2013-07-01

    This paper presents the results of electron beam tracking simulations for a 30 MeV standing wave electron linac at Electron Beam Centre Kharghar, Navi Mumbai, India. For the pulsed mode operation of the present linac preferential operation parameters have been determined from the results of beam dynamics studies. This electron accelerator is a general purpose facility for generation of Bremsstrahlung X-rays and neutron scattering experiments. This electron accelerator-based experimental neutron facility will be used for measurement of neutron cross-section (n,γ), (n, xn) and (n, f) reactions at different energies for various materials and material irradiation studies.

  4. Ion beam analysis in cultural heritage studies: Milestones and perspectives

    SciTech Connect

    Dran, Jean-Claude; Calligaro, Thomas

    2013-07-18

    For three decades, ion beam analysis (IBA) in external mode was considered as the best choice for the characterisation of cultural heritage materials, as it combines excellent analytical performance and non-invasive character. However, in recent years, other analytical techniques arose as serious competitors, such as those based on synchrotron radiation (X-ray absorption, fluorescence or diffraction) or those using portable instruments (XRF, micro-Raman). It is shown that nevertheless IBA remains unmatched thanks to two unique features, namely the analysis of light elements and the high-resolution 3D chemical imaging.

  5. Inter-dye distance distributions studied by a combination of single-molecule FRET-filtered lifetime measurements and a weighted accessible volume (wAV) algorithm.

    PubMed

    Höfig, Henning; Gabba, Matteo; Poblete, Simón; Kempe, Daryan; Fitter, Jörg

    2014-01-01

    Förster resonance energy transfer (FRET) is an important tool for studying the structural and dynamical properties of biomolecules. The fact that both the internal dynamics of the biomolecule and the movements of the biomolecule-attached dyes can occur on similar timescales of nanoseconds is an inherent problem in FRET studies. By performing single-molecule FRET-filtered lifetime measurements, we are able to characterize the amplitude of the motions of fluorescent probes attached to double-stranded DNA standards by means of flexible linkers. With respect to previously proposed experimental approaches, we improved the precision and the accuracy of the inter-dye distance distribution parameters by filtering out the donor-only population with pulsed interleaved excitation. A coarse-grained model is employed to reproduce the experimentally determined inter-dye distance distributions. This approach can easily be extended to intrinsically flexible proteins allowing, under certain conditions, to decouple the macromolecule amplitude of motions from the contribution of the dye linkers.

  6. Interplay of space-charge and beam-beam effects in a collider

    SciTech Connect

    Fedotov, A.V.; Blaskiewicz, M.; Fischer, W.; Satogata, T.; Tepikian, S.

    2010-09-27

    Operation of a collider at low energy or use of cooling techniques to increase beam density may result in luminosity limitation due to the space-charge effects. Understanding of such limitation became important for Low-Energy RHIC physics program with heavy ions at the center of mass energies of 5-20 GeV/nucleon. For a collider, we are interested in a long beam lifetime, which limits the allowable space-charge tune shift. An additional complication comes from the fact that ion beams are colliding, which requires careful consideration of the interplay of direct space-charge and beam-beam effects. This paper summarizes the initial observations during experimental studies in RHIC at low energies.

  7. Lifetime of the Highly Efficient H- Ion Sources

    SciTech Connect

    Bollinger, D.S.; Dudnikov, V.G.; Faircloth, D.C.; Lawrie, S.R.; /Rutherford

    2012-05-01

    Factors limiting the operating lifetime of Compact Surface Plasma Sources (CSPS) are analyzed and possible treatments for lifetime enhancement are considered. Noiseless discharges with lower gas and cesium densities are produced in experiments with modified discharge cells. With these discharge cells it is possible to increase the emission aperture and extract the same beam with a lower discharge current and with correspondingly increased source lifetime. A design of an advanced CSPS is presented. Optimization of the discharge cells in a Penning H{sup -} ion source is a viable method for increasing the phase space of the stable region for noiseless discharge production. With this method, cesium usage would be decreased, potentially resulting in longer source lifetimes.

  8. Studies of the beam extraction system of the GTS-LHC electron cyclotron resonance ion source at CERN

    NASA Astrophysics Data System (ADS)

    Toivanen, V.; Küchler, D.

    2016-02-01

    The 14.5 GHz GTS-LHC Electron Cyclotron Resonance Ion Source (ECRIS) provides multiply charged heavy ion beams for the CERN experimental program. The GTS-LHC beam formation has been studied extensively with lead, argon, and xenon beams with varied beam extraction conditions using the ion optical code IBSimu. The simulation model predicts self-consistently the formation of triangular and hollow beam structures which are often associated with ECRIS ion beams, as well as beam loss patterns which match the observed beam induced markings in the extraction region. These studies provide a better understanding of the properties of the extracted beams and a way to diagnose the extraction system performance and limitations, which is otherwise challenging due to the lack of direct diagnostics in this region and the limited availability of the ion source for development work.

  9. Studies of the beam extraction system of the GTS-LHC electron cyclotron resonance ion source at CERN.

    PubMed

    Toivanen, V; Küchler, D

    2016-02-01

    The 14.5 GHz GTS-LHC Electron Cyclotron Resonance Ion Source (ECRIS) provides multiply charged heavy ion beams for the CERN experimental program. The GTS-LHC beam formation has been studied extensively with lead, argon, and xenon beams with varied beam extraction conditions using the ion optical code IBSimu. The simulation model predicts self-consistently the formation of triangular and hollow beam structures which are often associated with ECRIS ion beams, as well as beam loss patterns which match the observed beam induced markings in the extraction region. These studies provide a better understanding of the properties of the extracted beams and a way to diagnose the extraction system performance and limitations, which is otherwise challenging due to the lack of direct diagnostics in this region and the limited availability of the ion source for development work.

  10. Studies of the beam extraction system of the GTS-LHC electron cyclotron resonance ion source at CERN.

    PubMed

    Toivanen, V; Küchler, D

    2016-02-01

    The 14.5 GHz GTS-LHC Electron Cyclotron Resonance Ion Source (ECRIS) provides multiply charged heavy ion beams for the CERN experimental program. The GTS-LHC beam formation has been studied extensively with lead, argon, and xenon beams with varied beam extraction conditions using the ion optical code IBSimu. The simulation model predicts self-consistently the formation of triangular and hollow beam structures which are often associated with ECRIS ion beams, as well as beam loss patterns which match the observed beam induced markings in the extraction region. These studies provide a better understanding of the properties of the extracted beams and a way to diagnose the extraction system performance and limitations, which is otherwise challenging due to the lack of direct diagnostics in this region and the limited availability of the ion source for development work. PMID:26932095

  11. Lifetime determination of the long-lived B 1Π g state in He 2* by photofragment spectroscopy

    NASA Astrophysics Data System (ADS)

    Kristensen, Martin; Keiding, Søren R.; van der Zande, Wim J.

    1989-12-01

    In a photofragment spectroscopy experiment, several laser transitions from the B 1Π g to the fast decaying F 1Σ u+ state of He 2* have been observed. The lifetime of the B 1Π g state has been estimated to 1.3±0.5 μs for both the B 1Π g+ and B 1Π g- components. This lifetime allows for the preparation of fast beams of 1Π g He 2* molecules, which can form the basis of a detailed spectroscopic study of the singlet system in He 2*. Since the two parity components of the B 1Π g state can have different dissociation channels, the observation of equal lifetime for the + and - components allows us to give an upper limit on the ratio between dissociation induced by predissociation and radiative decay.

  12. Socioeconomic status during lifetime and cognitive impairment no-dementia in late life: the population-based aging in the Chianti Area (InCHIANTI) Study.

    PubMed

    Marengoni, Alessandra; Fratiglioni, Laura; Bandinelli, Stefania; Ferrucci, Luigi

    2011-01-01

    Thousand and twelve dementia-free elderly (60–98 years old) enrolled in the InChianti Study (Italy) were evaluated at baseline (1998–2000) and at 3-year follow-up (2001–2003) with the aim of analyzing the association of lifetime socioeconomic status (SES) with prevalent and incident cognitive impairment no-dementia (CIND). SES was defined from information on formal education, longest held occupation, and financial conditions through life. CIND was defined as age-adjusted Mini-Mental State Examination score one standard deviation below the baseline mean score of participants without dementia. Logistic regression and Cox proportional-hazards models were used to estimate the association of SES with CIND. Demographics,occupation characteristics (i.e., job stress and physical demand), cardiovascular diseases, diabetes, apolipoprotein E (APOE)genotype, smoking, alcohol consumption, depressive symptoms, and C-reactive protein were considered potential confounders.Prevalence of CIND was 17.7%. In the fully adjusted model, low education (OR = 2.1; 95% confidence intervals, CI = 1.4 to 3.2)was associated with prevalent CIND. Incidence rate of CIND was 66.0 per 1000 person-years. Low education (HR = 1.7; 95% CI = 1.04 to 2.6) and manual occupation (HR = 1.9; 95% CI = 1.0 to 3.6) were associated with incident CIND. Among covariates,high job-related physical demand was associated with both prevalent and incident CIND (OR = 1.6; 95% CI = 1.1 to 2.4 and HR= 1.5; 95% CI = 1.0 to 2.3). After stratification for education, manual occupation was still associated with CIND among participants with high education (HR = 2.2; 95% CI = 1.2 to 4.3 versus HR= 1.4; 95% CI = 0.2 to 10.4 among those with low education). Proxy markers of lifetime SES (low education, manual occupation and high physical demand) are cross-sectional correlates of CIND and predict incident CIND over a three-year follow-up.

  13. Preparation, characterization, and properties of PMMA-doped polymer film materials: a study on the effect of terbium ions on luminescence and lifetime enhancement.

    PubMed

    Zhang, Hui-Jie; Fan, Rui-Qing; Wang, Xin-Ming; Wang, Ping; Wang, Yu-Lei; Yang, Yu-Lin

    2015-02-14

    Poly(methylmethacrylate) (PMMA) doped with Tb-based imidazole derivative coordination polymer {[Tb(3)(L)(μ(3)-OH)(7)]·H(2)O}(n) (1) (L = N,N'-bis(acetoxy)biimidazole) was synthesized and its photophysical properties were studied. The L'(L' = N,N'-bis(ethylacetate)biimidazole) ligand was synthesized by an N-alkylation reaction process followed by ester hydrolysis to produce ligand L. Polymer 1 and ligand L' have been characterized by (1)H NMR and IR spectroscopy, elemental analysis, PXRD and X-ray single-crystal diffraction. Coordination polymer 1 is the first observation of a CdCl(2) structure constructed with hydroxy groups and decorated by ligand L in lanthanide N-heterocyclic coordination polymers. In the 2D layered structure of 1, each Tb3 metal center is connected with three Tb1 and three Tb2 metal centers by seven hydroxyl groups in different directions, resulting in a six-membered ring. After doping, not only the luminescence intensity and lifetime enhanced, but also their thermal stability was increased in comparison with 1. When 1 was doped into poly(methylmethacrylate) (1@PMMA), polymer film materials were formed with the PMMA polymer matrix (w/w = 2.5%-12.5%) acting as a co-sensitizer for Tb(3+) ions. The luminescence intensity of the Tb(3+) emission at 544 nm increases when the content of Tb(3+) was 10%. The lifetime of 1@PMMA (914.88 μs) is more than four times longer than that of 1 (196.24 μs). All τ values for the doped polymer systems are higher than coordination polymer 1, indicating that radiative processes are operative in all the doped polymer films. This is because PMMA coupling with the O-H oscillators from {[Tb(3)(L)(μ(3)-OH)(7)]·H(2)O}(n) can suppress multiphonon relaxation. According to the variable-temperature luminescence (VT-luminescence) investigation, 1@PMMA was confirmed to be a stable green luminescent polymer film material.

  14. Experimental study of laser beam propagation in turbulent atmosphere

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Ping; He, Wu-Guang; Wu, Jian

    2009-05-01

    Intensity of atmospheric turbulence may overly affect bit error rate for a ground-based laser wireless communication system, so it is necessary to measure of atmospheric turbulence intensity and fluctuation of image centroid while laser beam propagates in turbulent atmosphere. In this paper, an experiment system is set up based on theory of light transmission in turbulent atmosphere. In the system, a laser named Nd : YAG is used horizontally to emit a laser beam with wavelength 1.06 μm on a platform at the height of 1.5 m. Three infrared CCD cameras are set at 200 m, 300 m(or 600 m) and 1000 m far from laser, which are applied to receive laser facula images from Lambertian boards, respectively. A lot of laser facula images are collected within some serial days under different periods of time every day, and hundreds of image frames are gathered at a time by making use of this experiment device. Fluctuation of image centroid is computed with these image frames, and the structure constant of atmospheric refractive index (C 2n) is also derived. Finally, a comparison is made between aforementioned C2n and those derived by meteorology factors.

  15. Optical studies of ion-beam synthesized metal alloy nanoparticles

    SciTech Connect

    Magudapathy, P. Srivatsava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Sairam, T. N.; Panigrahi, B. K.

    2015-06-24

    Au{sub x}Ag{sub 1-x} alloy nanoparticles with tunable surface plasmon resonance (SPR) have been synthesized on a silica glass substrate. A small Au foil on an Ag foil is irradiated as target substrates such that ion beam falls on both Ag foil and Au foils. Silica slides are kept at an angle ∼45° with respect to the metallic foils. While irradiating the metallic foils with 100 keV Ar{sup +} ions, sputtered Au and Ag atoms get deposited on the silica-glass. In this configuration the foils have been irradiated by Ar{sup +} ions to various fluences at room temperature and the sputtered species are collected on silica slides. Formation of Au{sub x}Ag{sub 1-x} nanoparticles has been confirmed from the optical absorption measurements. With respect to the exposure area of Au and Ag foils to the ion beam, the SPR peak position varies from 450 to 500 nm. Green photoluminescence has been observed from these alloy metal nanoparticles.

  16. Runaway beam studies during disruptions at JET-ILW

    NASA Astrophysics Data System (ADS)

    Reux, C.; Plyusnin, V.; Alper, B.; Alves, D.; Bazylev, B.; Belonohy, E.; Brezinsek, S.; Decker, J.; Devaux, S.; de Vries, P.; Fil, A.; Gerasimov, S.; Lupelli, I.; Jachmich, S.; Khilkevitch, E. M.; Kiptily, V.; Koslowski, R.; Kruezi, U.; Lehnen, M.; Manzanares, A.; Mlynář, J.; Nardon, E.; Nilsson, E.; Riccardo, V.; Saint-Laurent, F.; Shevelev, A. E.; Sozzi, C.

    2015-08-01

    Runaway electrons (RE) during disruptions are a concern for future tokamaks including ITER with its metallic wall. Although RE are rare in spontaneous disruptions with the JET ITER-like Wall (JET-ILW), RE beams up to 380 kA were obtained using massive injection (MGI) of argon in JET-ILW divertor discharges. Entry points into the RE domain defined by operational parameters (toroidal field, argon fraction in MGI) are unchanged but higher RE currents have been obtained inside the JET-ILW MGI-generated RE domain when compared to JET-C. This might be due to the influence of the metallic wall on the current quench plasma. Temperatures of 900 °C have been observed following RE impacts on beryllium tiles. Heat deposition depth of ∼2 mm has to be assumed to match the tile cooling time. 3D simulations of the RE energy deposition using the ENDEP/MEMOS codes show that material melting is unlikely with 100 kA RE beams.

  17. Study of a microwave power source for a two-beam accelerator

    SciTech Connect

    Houck, T.L.

    1994-08-15

    A theoretical and experimental study of a microwave power source suitable for driving a linear e{sup +}e{sup {minus}} collider is reported. The power source is based on the Relativistic Klystron Two-Beam Accelerator (RK-TBA) concept, is driven by a 5-MeV, 1-kA induction accelerator electron beam, and operates at X-band frequencies. The development of a computer code to simulate the transverse beam dynamics of an intense relativistic electron beam transiting a system of microwave resonant structures is presented. This code is time dependent with self-consistent beam-cavity interactions and uses realistic beam parameters. Simulations performed with this code are compared with analytical theory and experiments. The concept of spacing resonant structures at distances equal to the betatron wavelength of the focusing system to suppress the growth of transverse instabilities is discussed. Simulations include energy spread over the beam to demonstrate the effect of Landau damping and establish the sensitivity of the betatron wavelength spacing scheme to errors in the focusing system. The design of the Reacceleration Experiment is described in detail and includes essentially all the issues related to a full scale RK-TBA microwave source. A total combined power from three output structures in excess of 170 MW with an amplitude stability of {+-}4% over a 25 ns pulse was achieved. The results of the experiment are compared to simulations used during the design phase to validate the various codes and methods used. The primary issue for the RK-TBA concept is identified as transverse beam instability associated with the excitation of higher order modes in the resonant structures used for extracting microwave power from the modulated beam. This work represents the first successful experimental demonstration of repeated cycles of microwave energy extraction from and reacceleration of a modulated beam.

  18. Beam dynamics studies of a helical X-band RF undulator

    SciTech Connect

    Shumail, M.; Bowden, G.; Chang, C.; Neilson, J.; Tantawi, S.

    2012-12-21

    We present beam dynamics studies of a proposed circularly polarized RF undulator cavity to be operated at 50 MW to yield the undulator strength parameter K= 0.7. A symplectic integration scheme is used for numerical studies. The expressions for field integrals of the RF undulator are also developed. Simulation results for the electron trajectories, showing off-axis drift and bunch defocusing, for 60 and 120 MeV beam energies are presented.

  19. Extended lifetime railgap switch

    SciTech Connect

    Cohn, D.B.; Mendoza, P.J.

    1988-02-02

    In a railgap switch of the type having an elongate blade electrode made of conductive material, an elongate housing made of insulating material for supporting the blade electrode and plate electrode in opposed relation extending in the same direction with the blade centered over the plate and separated therefrom by a gap, and a gas filling the housing and the gap, the gas being selected to breakdown and switch from a highly insulative state to a highly conductive state upon application of a high voltage across the blade and plate electrodes, the improvement is described comprising: forming the blade with laterally extending transverse wing portions at the edge of the blade and adjacent the gap so as to extend in spaced parallel relation to the surface of the plate, the blade generally following the contour thereof to form an inverted T-shape structure with the wing portions extending transversely of the elongate dimension of the blade. The wing portions terminating in a pair of spaced parallel edges extending along the elongate direction of the blade to thereby create two spaced elongate edges along which arcs form serving to divide the erosion effects of discharge between them, the current through each edge being one-half of that in single-edge devices with ablation wear reduced accordingly to give significantly larger switch lifetime. The blade and wing portions limiting ablation erosion of the edges in a direction generally align with the plate contour so that the edge-to-plate separation remains substantially constant.

  20. Expanded studies of linear collider final focus systems at the Final Focus Test Beam

    SciTech Connect

    Tenenbaum, P.G.

    1995-12-01

    In order to meet their luminosity goals, linear colliders operating in the center-of-mass energy range from 3,50 to 1,500 GeV will need to deliver beams which are as small as a few Manometers tall, with x:y aspect ratios as large as 100. The Final Focus Test Beam (FFTB) is a prototype for the final focus demanded by these colliders: its purpose is to provide demagnification equivalent to those in the future linear collider, which corresponds to a focused spot size in the FFTB of 1.7 microns (horizontal) by 60 manometers (vertical). In order to achieve the desired spot sizes, the FFTB beam optics must be tuned to eliminate aberrations and other errors, and to ensure that the optics conform to the desired final conditions and the measured initial conditions of the beam. Using a combination of incoming-beam diagnostics. beam-based local diagnostics, and global tuning algorithms, the FFTB beam size has been reduced to a stable final size of 1.7 microns by 70 manometers. In addition, the chromatic properties of the FFTB have been studied using two techniques and found to be acceptable. Descriptions of the hardware and techniques used in these studies are presented, along with results and suggestions for future research.

  1. Silver vanadium oxide and silver vanadium phosphorous oxide dissolution kinetics: a mechanistic study with possible impact on future ICD battery lifetimes.

    PubMed

    Bock, David C; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S

    2013-10-14

    Material design strategies for energy storage applications can be considered in two major categories: (1) control of structure and composition and (2) material dimensional control such as the implementation of nanomaterials. Characterization of electrochemical properties determines energy content and possible viability for potential application. Equally critical yet more challenging is quantifying the non-Faradaic parasitic reactions of the active materials and the relationship to battery life. Understanding the significant factors associated with battery lifetimes for the implantable cardioverter defibrillator (ICD) is critical for the development of new ICD batteries. In situ dissolution of the cathode material has been identified as a major factor in premature end of life for ICD batteries. This study contains the kinetic analyses of silver and vanadium dissolution from the benchmark silver vanadium oxide (SVO) material and two silver vanadium phosphorous oxide (SVPO-H and SVPO-R) materials with differing physical properties in a non-aqueous ICD battery electrolyte. A comparison of the kinetic and mechanistic results for SVO, SVPO-H and SVPO-R provides insight for future material design approaches.

  2. Luminescence, lifetime, and quantum yield studies of redispersible Eu3+-doped GdPO4 crystalline nanoneedles: Core-shell and concentration effects

    NASA Astrophysics Data System (ADS)

    Yaiphaba, N.; Ningthoujam, R. S.; Singh, N. Shanta; Vatsa, R. K.; Singh, N. Rajmuhon; Dhara, Sangita; Misra, N. L.; Tewari, R.

    2010-02-01

    Crystalline nanoneedles of Eu3+-doped GdPO4 and Eu3+-doped GdPO4 covered with GdPO4 shell (core shell) have been prepared at relatively low temperature of 150 °C in ethylene glycol medium. From luminescence study, asymmetric ratio of Eu3+ emission at 612 nm (electric dipole transition) to 592 nm (magnetic dipole transition) is found to be less than one. Maximum luminescence was observed from the nanoparticles with Eu3+ concentration of 5 at. %. For a fixed concentration of Eu3+ doping, there is an improvement in emission intensity for core-shell nanoparticles compared to that for core. This has been attributed to effective removal of surface inhomogeneities around Eu3+ ions present on the surface of core as well as the passivation of inevitable surface states, defects or capping ligand (ethylene glycol) of core nanoparticles by bonding to the shell. Lifetime for D50 level of Eu3+ was found to increase three times for core-shell nanoparticles compared to that for core confirming the more Eu3+ ions with symmetry environment in core shell. For 5 at. % Eu3+-doped GdPO4, quantum yield of 19% is obtained. These nanoparticles are redispersible in water, ethanol, or chloroform and thus will be useful in biological labeling. The dispersed particles are incorporated in polymer-based films that will be useful in display devices.

  3. Numerical simulation to study the transient self focusing of laser beam in plasma

    SciTech Connect

    Sharma, R. P.; Hussain, Saba Gaur, Nidhi

    2015-02-15

    In this paper, we present the numerical simulation for the coupled system of equations governing the dynamics of laser and Ion Acoustic Wave (IAW) in a collisionless plasma, when the coupling between the waves is through ponderomotive non-linearity. The nonlinear evolution of the laser beam is studied when the pump laser is perturbed by a periodic perturbation. By changing the perturbation wave number, we have studied its effect on the nonlinear evolution pattern of laser beam. In order to have a physical insight into the nonlinear dynamics of laser beam evolution in time and space, we have studied the laser and IAW spectra containing spatial harmonics. The magnitude of these harmonics changes with time and leads to time dependent localization of laser beam in spatial domain. The nonlinear dynamics of this localization is investigated in detail by using simulation and a semi-analytical model.

  4. Supercontinuum Stimulated Emission Depletion Fluorescence Lifetime Imaging

    SciTech Connect

    Lesoine, Michael; Bose, Sayantan; Petrich, Jacob; Smith, Emily

    2012-06-13

    Supercontinuum (SC) stimulated emission depletion (STED) fluorescence lifetime imaging is demonstrated by using time-correlated single-photon counting (TCSPC) detection. The spatial resolution of the developed STED instrument was measured by imaging monodispersed 40-nm fluorescent beads and then determining their fwhm, and was 36 ± 9 and 40 ± 10 nm in the X and Y coordinates, respectively. The same beads measured by confocal microscopy were 450 ± 50 and 430 ± 30 nm, which is larger than the diffraction limit of light due to underfilling the microscope objective. Underfilling the objective and time gating the signal were necessary to achieve the stated STED spatial resolution. The same fluorescence lifetime (2.0 ± 0.1 ns) was measured for the fluorescent beads by using confocal or STED lifetime imaging. The instrument has been applied to study Alexa Fluor 594-phalloidin labeled F-actin-rich projections with dimensions smaller than the diffraction limit of light in cultured cells. Fluorescence lifetimes of the actin-rich projections range from 2.2 to 2.9 ns as measured by STED lifetime imaging.

  5. Lifetime Blinking in Non Blinking Quantum Dots

    NASA Astrophysics Data System (ADS)

    Klimov, Victor; Ghosh, Yagnaseni; Steinbrueck, Andrea; Hollingsworth, Jennifer; Htoon, Han; Galland, Christophe

    2012-02-01

    Photoluminescence (PL) blinking is a common property of nanoscale light emitters. Nanocrystal quantum dots have often been used as model systems in studies of this intriguing phenomenon. Here, we use recently developed thick-shell CdSe/CdS NQDs to demonstrate a new regime of blinking where discrete fluctuations in the PL lifetime (``lifetime blinking'') occur without appreciable changes in the PL intensity. Single-dot measurements under controlled electrochemical charge injection [1] yield the PL lifetimes of neutral and charged excitons. We show that the observed ``lifetime blinking'' are due to random charging/discharging of the nanocrystal [2]. Indeed, the injection of electrons does not appreciably modify the PL quantum yield, which explains the coexistence of a nonblinking intensity with a ``blinking'' lifetime. At higher excitation power, charged excitons dominate the PL emission. We build a quantitative model showing that nanocrystal charging is caused by Auger-assisted ejection of a hole, producing negatively charged species. Importantly, Auger recombination that involves excitation of an electron is suppressed while hole-based processes remain efficient.[4pt] [1] Galland et al., Nature 479, 203-207 (2011)[0pt] [2] Galland et al., Submitted (2011)

  6. Figure of merit studies of beam power concepts for advanced space exploration

    NASA Technical Reports Server (NTRS)

    Miller, Gabriel; Kadiramangalam, Murali N.

    1990-01-01

    Surface to surface, millimeter wavelength beam power systems for power transmission on the lunar base were investigated. Qualitative/quantitative analyses and technology assessment of 35, 110 and 140 GHz beam power systems were conducted. System characteristics including mass, stowage volume, cost and efficiency as a function of range and power level were calculated. A simple figure of merit analysis indicates that the 35 GHz system would be the preferred choice for lunar base applications, followed closely by the 110 GHz system. System parameters of a 35 GHz beam power system appropriate for power transmission on a recent lunar base concept studied by NASA-Johnson and the necessary deployment sequence are suggested.

  7. A study of laser-beam welding conducted at the Centre for Laser Technologies of Metals

    NASA Astrophysics Data System (ADS)

    Antoszewski, Bogdan; Gradoń, Ryszard; Trela, Paweł; Cendrowicz, Edward

    2013-01-01

    The study reported here is part of a larger research project on laser-beam welding conducted at the Centre for Laser Technologies of Metals. The primary objectives were to compare laser-beam welding with a conventional process when used for longitudinal seams in street lamp posts, to select the process parameters for girth welds in cylindrical high-strength steel machine elements, and to assess whether laser-beam welding can be used for magnesium alloys. The paper includes recommendations for the selection of welding parameters.

  8. Experimental Study on Nonlinear Vibrations of Fixed-Fixed Curved Beams

    NASA Astrophysics Data System (ADS)

    Kumar, Ajay; Patel, B. P.

    2016-07-01

    Nonlinear dynamic behavior of fixed-fixed shallow and deep curved beams is studied experimentally using non-contact type of electromagnetic shaker and acceleration measurements. The frequency response obtained from acceleration measurements is found to be in fairly good agreement with the computational response. The travellingwave phenomenon along with participation of higher harmonics and softening nonlinearity are observed. The experimental results on the internal resonance of curved beams due to direct excitation of anti-symmetric mode are reported for the first time. The deep curved beam depicts chaotic response at higher excitation amplitude.

  9. Study of Electron-Beam Propagation through Preionized Dense Foam Plasmas

    SciTech Connect

    Jung, R.; Osterholz, J.; Loewenbrueck, K.; Kiselev, S.; Pretzler, G.; Pukhov, A.; Willi, O.; Kar, S.; Borghesi, M.; Nazarov, W.; Karsch, S.; Clarke, R.; Neely, D.

    2005-05-20

    The transport of an intense electron-beam produced by the Vulcan petawatt laser through dense plasmas has been studied by imaging with high resolution the optical emission due to electron transit through the rear side of coated foam targets. It is observed that the MeV-electron beam undergoes strong filamentation and the filaments organize themselves in a ringlike structure. This behavior has been modeled using particle-in-cell simulations of the laser-plasma interaction as well as of the transport of the electron beam through the preionized plasma. In the simulations the filamentary structures are reproduced and attributed to the Weibel instability.

  10. Scintillating screens sensitivity and resolution studies for low energy, low intensity beam diagnostics.

    PubMed

    Harasimowicz, Janusz; Cosentino, Luigi; Finocchiaro, Paolo; Pappalardo, Alfio; Welsch, Carsten P

    2010-10-01

    In order to investigate the limits of scintillating screens for beam profile monitoring in the ultra-low energy, ultra-low intensity regime, CsI:Tl, YAG:Ce, and a Tb glass-based scintillating fiber optic plate (SFOP) were tested. The screens response to 200 and 50 keV proton beams with intensities ranging from a few picoampere down to the subfemtoampere region was examined. In the following paper, the sensitivity and resolution studies are presented in detail for CsI:Tl and the SFOP, the two most sensitive screens. In addition, a possible use of scintillators for ultra-low energy antiproton beam monitoring is discussed.

  11. Comparative studies of defects in GaAs on silicon substrates using electron-beam-induced current and transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Humphreys, T. P.; Hamaguchi, N.; Bedair, S. M.; Tarn, J. C. L.; El-Masry, N.; Radzimski, Z. J.

    1988-10-01

    We report the use of electron-beam-induced current imaging and transmission electron microscopy techniques to examine defects in heteroepitaxial films of GaAs on Si. The electron-beam-induced current method has been successfully applied to obtain dark spot micrographs revealing the distribution of electrically active defects in the GaAs epilayer. Relatively large areas of dark contrast corresponding to regions of high defect density (enhanced recombination) have been identified. In contrast, within the intervening regions between these electrically active centers, areas associated with uniform electrical quality have been observed. Furthermore, in a comparative study of the microstructural character of defects using transmission electron microscopy, we have also identified corresponding regions of high and low defect density. The role of electrically active defects in determining the minority carrier lifetimes and diffusion lengths in the GaAs epilayer is also discussed. Moreover, it has been demonstrated that an electron-beam-induced current technique is an appropriate alternative to transmission electron microscopy in delineating the contribution and distribution of electrically active of defects in large-area heteroepitaxial GaAs on silicon samples.

  12. Lifetime measurements for bottom hadrons

    SciTech Connect

    Wolf, G.

    1984-09-01

    The review of lifetime measurements of bottom hadrons begins with a first measurement by JADE, followed by similar measurements by MAC and MKII groups. New MAC data are reviewed based on a total of 75,000 multihadron events taken at a c.m. energy of 29 GeV. According to Monte Carlo calculations, 18% of the lepton candidates stem from charm decay and roughly 30% were misidentified hadrons. DELCO studied electrons obtained from 42,000 multihadron events at 29 GeV. The electrons were identified by means of Cerenkov counters. JADE analayzed 22,000 multihadron events at 35 GeV. Data were analyzed using two methods - one using a sample of b-enriched events, and the other using weighted distributions. The TASSO results were obtained with two different configurations of the detector - one of which used a drift chamber and the other a vertex detector. (LEW)

  13. Ion-beam depth-profiling studies of leached glasses

    SciTech Connect

    Houser, C.A.; Tsong, I.S.T.; White, W.B.; Wintenberg, A.L.; Miller, P.D.; Moak, C.D.

    1981-01-01

    Ion-beam depth-profiling was carried out on three different glasses leached (or hydrated) in deionized water using /sup 1/H(/sup 19/F,..cap alpha gamma..)/sup 16/O nuclear reaction, secondary ion mass spectrometry (SIMS) and sputter-induced photon spectrometry (SIPS) techniques. The depth-profiles show an interdiffusion mechanism in which the sodium ions in the glass are depleted and replaced by hydrogen (H/sup +/) or hydronium (H/sub 3/O/sup +/) ions from the solution. The leaching behavior does not show significant difference whether the glass surface is fractured or polished. Problems of mobile ion migration caused by ion bombardment and loss of hydrogen during analysis are discussed.

  14. Ionosphere/microwave beam interaction study. [satellite solar energy conversion

    NASA Technical Reports Server (NTRS)

    Duncan, L. M.; Gordon, W. E.

    1977-01-01

    A solar power satellite microwave power density of 20mw sq cm was confirmed as the level where nonlinear interactions may occur in the ionosphere, particularly at 100 km altitude. Radio wave heating at this altitude, produced at the Arecibo Observatory, yielded negative results for radio wave heating of an underdense ionosphere. Overdense heating produced striations in the ionosphere which may cause severe radio frequency interference problems under certain conditions. The effects of thermal self-focusing are shown to be limited severely geographically. The aspect sensitivity of field-aligned striations makes interference-free regions above magnetic latitude about 60 deg. A test program is proposed to simulate the interaction of the SPS beam with the ionosphere, to measure the effects of the interaction on the ionosphere and on communication and navigation systems, and to interpret the results.

  15. Recent Studies of Hypernuclei Formation with Electron Beams at MAMI

    NASA Astrophysics Data System (ADS)

    Achenbach, Patrick; Ayerbe Gayoso, Carlos; Böhm, Ralph; Borodina, Olga; Bosnar, Damir; Bozkurt, Vakkas; Debenjak, Luka; Distler, Michael O.; Esser, Anselm; Friščić, Ivica; Fujii, Yuu; Gogami, Toshiyuki; Gómez Rodríguez, Mar; Hashimoto, Osamu; Hirose, Satoshi; Kanda, Hiroki; Kaneta, Masashi; Kim, Eunhee; Kusaka, Junichiro; Margaryan, Amur; Merkel, Harald; Müller, Ulrich; Nagao, Sho; Nakamura, Satoshi N.; Pochodzalla, Josef; Rappold, Christophe; Reinhold, Joerg; Saito, Takehiko R.; Sanchez Lorente, Alicia; Sánchez Majos, Salvador; Schlimme, B. Sören; Schoth, Matthias; Schulz, Florian; Sfienti, Concettina; Širca, Simon; Tang, Liguang; Thiel, Michaela; Tsukada, Kyo

    2014-08-01

    At the Mainz Microtron MAMI exploratory experiments on the spectroscopy of mesonic weak decays (MWD) of electroproduced Λ-hypernuclei were performed. A unique setup was realized to use the broad momentum-band kaon spectrometer K aos at zero degree angle with respect to the high-intensity electron beam direction to tag strangeness producing processes. A sample of order 103 MWD from a beryllium target was collected by the coincidence technique with the high-resolution multi-spectrometer facility of the A1 Collaboration. It is conjectured that this sample contains monochromatic two-body decays from stopped hyperfragment decays as well as a wide momentum distribution of quasi-free produced Λ- and Σ-hyperon decays and three-body decays from hyperfragments. Stopped hyperfragments will be identified as monochromatic peaks in the π - momentum spectrum from which their masses can be extracted with a precision of 50 keV/ c 2.

  16. Computational study of ion beam extraction phenomena through multiple apertures

    SciTech Connect

    Hu, Wanpeng; Sang, Chaofeng; Tang, Tengfei; Wang, Dezhen; Li, Ming; Jin, Dazhi; Tan, Xiaohua

    2014-03-15

    The process of ion extraction through multiple apertures is investigated using a two-dimensional particle-in-cell code. We consider apertures with a fixed diameter with a hydrogen plasma background, and the trajectories of electrons, H{sup +} and H{sub 2}{sup +} ions in the self-consistently calculated electric field are traced. The focus of this work is the fundamental physics of the ion extraction, and not particular to a specific device. The computed convergence and divergence of the extracted ion beam are analyzed. We find that the extracted ion flux reaching the extraction electrode is non-uniform, and the peak flux positions change according to operational parameters, and do not necessarily match the positions of the apertures in the y-direction. The profile of the ion flux reaching the electrode is mainly affected by the bias voltage and the distance between grid wall and extraction electrode.

  17. Transport studies of LPA electron beam towards the FEL amplification at COXINEL

    NASA Astrophysics Data System (ADS)

    Khojoyan, M.; Briquez, F.; Labat, M.; Loulergue, A.; Marcouillé, O.; Marteau, F.; Sharma, G.; Couprie, M. E.

    2016-09-01

    Laser Plasma Acceleration (LPA) [1] is an emerging concept enabling to generate electron beams with high energy, high peak current and small transverse emittance within a very short distance. The use of LPA can be applied to the Free Electron Laser (FEL) [2] case in order to investigate whether it is suitable for the light amplification in the undulator. However, capturing and guiding of such beams to the undulator is very challenging, because of the large divergence and high energy spread of the electron beams at the plasma exit, leading to large chromatic emittances. A specific beam manipulation scheme was recently proposed for the COXINEL (Coherent X-ray source inferred from electrons accelerated by laser) setup, which makes an advantage from the intrinsically large chromatic emittance of such beams [3]. The electron beam transport is studied using two simulation codes: a SOLEIL in-house one and ASTRA [4]. The influence of the collective effects on the electron beam performance is also examined.

  18. A simulation study on energy recovery from spent electron beams in an S-band linac

    NASA Astrophysics Data System (ADS)

    Masuda, K.; Matsumura, S.; Kii, T.; Ohgaki, H.; Yamazaki, T.; Nagasaki, K.; Yoshikawa, K.

    2003-07-01

    The feasibility of energy recovery with an S-band linac was studied based on two-dimensional particle-in-cell simulations. A 1-m standing-wave accelerating tube with 20 cells was chosen for the numerical model, with a 4.5-cell RF gun as the injector which is to be used for our IR FEL project. For ample reduction of beam energy to the dump with a typical beam energy from the gun of 5.49 MeV, the phase acceptance of the re-injection of the spent beam is found to be ±0.16 π rad which corresponds to a feasible longitudinal deviation of ±27 ps. Furthermore, for a lower beam energy to the dump and a higher wall plug efficiency, simulations with a lower beam energy of 2.42 MeV from the gun were carried out. Counter re-injection of the spent beam is found to be effective for compensating longitudinal velocity variations of low-energy beams along the tube, while degradation in the transverse emittance due to enhanced space-charge effect was found.

  19. Lattice design and beam dynamics studies for the PLS-II

    NASA Astrophysics Data System (ADS)

    Shin, S.; Kim, D.; Hwang, I.; Kim, M.; Choi, J.; Liu, G.; Hou, J.; Chunjarean, S.; Kim, K.-R.; Huang, J.; Nam, S.

    2013-08-01

    Pohang Light Source (PLS) [1] had operated for 14 year successfully. To meet the request of the increasing user community, the PLS-II that is the upgrade project of PLS have been carried out. Main design goals of the PLS-II lattice are to increase beam energy to 3 GeV, to increase number of insertion devices by factor of two (20 IDs), to increase beam current to 400 mA and to reduce beam emittance below 10 nm with existing PLS tunnel and injection system. Following the desired design criteria, DBA lattice had been chosen such that the full storage ring includes 12 long straight sections and 12 short straight sections for installation of insertion devices with keeping beam emittance as small as possible. Through the six months of commissioning in the later half of 2011 and user operation in full period of 2012, we have successfully operated 14 insertion devices operation and top-up operation with 200 mA beam current and 5.8 nm beam emittance. It is especially important that good understanding of the machine operation and limitations can be achieved by comparison of experimental and simulation data during realizing final PLS-II goal and stable operation. Therefore, this paper describes the results of lattice design and beam dynamics studies for the PLS-II [2,3].

  20. Experimental study of phase locking of fiber collimators using internal beam-tail interference

    NASA Astrophysics Data System (ADS)

    Beresnev, Leonid A.; Vorontsov, Mikhail A.; Weyrauch, Thomas; Carhart, Gary; Lachinova, Svetlana L.; Liu, Jiang

    2011-02-01

    Experimental study of internal phase locking of a seven fiber collimator array is presented. As a metric for the feedback loop the periphery areas (tails) of beams outgoing from three adjacent fiber tips are used before the beams are clipped by the lens apertures. The "intercepted" tails of beams are redirected back into the collimator array forming an interference pattern located between adjacent collimators. Optical energy from one region of the pattern is selected by a pinhole, detected with a photo-diode and used as a metric signal for an SPGD controller to lock the phase of the three adjacent beam tails. The non-common phase difference of the outgoing wavefronts from these three collimators can be manipulated by altering the position of the pinhole in focal plane of the interference pattern and is removed (set to "zero" or 2π increments) by a displacement selected to produce the expected far field interference pattern. To phase lock the beams from seven collimators arranged in a hexagonal array, three pinholes, each of which receives some light from the center collimator are used. A sum of the signals from the three photo-diodes placed behind these pinholes is used to lock the phase of the six periphery beams to the central uncontrolled reference without beam splitters or a remote target-in-theloop metric.

  1. Three-dimensional numerical studies of the temperature anisotropy instability in intense charged particle beams

    NASA Astrophysics Data System (ADS)

    Startsev, Edward A.; Davidson, Ronald C.; Qin, Hong

    2005-05-01

    In neutral plasmas with a uniform magnetic field and strongly anisotropic distribution function (T∥/T⊥≪1) an electrostatic Harris-type collective instability may develop if the plasma is sufficiently dense. Such anisotropies develop naturally in accelerators, and a similar instability may lead to a deterioration of the beam quality in a one-component nonneutral charged particle beam. The instability may also lead to an increase in the longitudinal velocity spread, which would make the focusing of the beam difficult and impose a limit on the minimum spot size achievable in heavy ion fusion experiments. This paper reports the results of recent numerical studies of the temperature anisotropy instability using the newly developed Beam Eigenmodes And Spectra (bEASt) code for space-charge-dominated, low-emittance beams with large tune depression (ν/ν0≪1). Such high-intensity beams are relevant to next-step experiments such as the Integrated Beam Experiment (IBX), which would serve as proof-of-principal experiment for heavy-ion fusion.

  2. Recent studies of the electron cloud induced beam instability at the Los Alamos PSR

    SciTech Connect

    Macek, Robert James; McCrady, Rodney C; Rybarcyk, Lawrence J; Zaugg, Thomas J

    2010-10-06

    Recent beam studies have focused on two aspects of the observed e-p instability at the Los Alamos Proton Storage Ring (PSR). Most recently it has been observed that a stable beam with the standard production bunch width (290 ns injected beam bunch width) will become e-p unstable when the bunch width is shortened to 200 ns or less. This was not the case years earlier when the ring RF operated at the exact 72.000 sub harmonic of the Linac bunch frequency. Experimental characteristics and possible explanations of this recent ''short pulse instability phenomenon'' will be presented. Other beam studies have focused on electron cloud generation, trapping and ejection from quadrupoles and are the focus of another talk. (auth)

  3. A study of refraction of a cylindrical laser beam in stratified liquid

    NASA Astrophysics Data System (ADS)

    Rinkevichyus, B. S.; Sapronov, M. V.; Pavlov, I. N.

    2016-09-01

    Refraction of a cylindrical laser beam in a transition layer at the interface of two liquids with different optical characteristics is studied theoretically and experimentally. A theoretical basis for calculations of the beam trajectory in the transition layer of stratified liquid is given. Two- and three-dimensional images (2D and 3D refractograms) of a cylindrical laser beam inside and outside the media are obtained on the basis of a tangential model of the refractive index profile. The influence of the parameters of the laser beam and media on the appearance of refractograms is studied and the optimal experimental conditions are selected with the use of computer simulation. A scheme of the setup for recording digital 2D refractogram and experimental results are presented. Algorithms for digitizing experimental images and for their comparison with calculated refractograms to determine the refractive index profile in the transition layer based on the tangential model are developed.

  4. A wire calorimeter for the SPIDER beam: Experimental tests and feasibility study

    NASA Astrophysics Data System (ADS)

    Pasqualotto, R.; Serianni, G.; Mario, I.; Veltri, P.; Zanini, M.; Cervaro, V.; Fasolo, D.

    2015-04-01

    To study and optimize negative ion production and acceleration, in view of the use of neutral beam injectors in the ITER project, the SPIDER test facility (particle energy 100keV; beam current 50A, distributed over 1280 beamlets) is under construction in Padova, with the aim of testing beam characteristics and to verify the source proper operation, by means of several diagnostic systems. An array of tungsten wires, directly exposed to the beam and consequently heated to high temperature, is used in similar experiments at IPP-Garching to study the beam optics, which is one of the most important issues, in a qualitative way. The present contribution gives a description of an experimental investigation of the behavior of tungsten wires under high heat loads in vacuum. Samples of tungsten wires are heated by electrical currents and the emitted light is measured by a camera in the 400-1100nm wavelength range, which is proposed as a calibration tool. Simultaneously, the voltage applied to the wire is measured to study the dependency of emissivity on temperature. The feasibility study of a wire calorimeter for SPIDER is finally proposed; to this purpose, the expected behaviour of tungsten with the two-dimensional beam profile in SPIDER is numerically addressed.

  5. A wire calorimeter for the SPIDER beam: Experimental tests and feasibility study

    SciTech Connect

    Pasqualotto, R. Serianni, G.; Veltri, P.; Cervaro, V.; Fasolo, D.; Mario, I.; Zanini, M.

    2015-04-08

    To study and optimize negative ion production and acceleration, in view of the use of neutral beam injectors in the ITER project, the SPIDER test facility (particle energy 100keV; beam current 50A, distributed over 1280 beamlets) is under construction in Padova, with the aim of testing beam characteristics and to verify the source proper operation, by means of several diagnostic systems. An array of tungsten wires, directly exposed to the beam and consequently heated to high temperature, is used in similar experiments at IPP-Garching to study the beam optics, which is one of the most important issues, in a qualitative way. The present contribution gives a description of an experimental investigation of the behavior of tungsten wires under high heat loads in vacuum. Samples of tungsten wires are heated by electrical currents and the emitted light is measured by a camera in the 400-1100nm wavelength range, which is proposed as a calibration tool. Simultaneously, the voltage applied to the wire is measured to study the dependency of emissivity on temperature. The feasibility study of a wire calorimeter for SPIDER is finally proposed; to this purpose, the expected behaviour of tungsten with the two-dimensional beam profile in SPIDER is numerically addressed.

  6. Spectroellipsometric and ion beam analytical studies on a glazed ceramic object with metallic lustre decoration

    NASA Astrophysics Data System (ADS)

    Lohner, T.; Agócs, E.; Petrik, P.; Zolnai, Z.; Szilágyi, E.; Kovács, I.; Szőkefalvi-Nagy, Z.; Tóth, L.; Tóth, A. L.; Illés, L.; Bársony, I.

    2014-11-01

    In this work recently produced and commercially available glazed ceramic object with metallic lustre decoration was studied by using a spectroscopic ellipsometer with rotating compensator. The thickness and metal content of the surface lustre layers are determined by ion beam analytical techniques, i.e., Rutherford backscattering spectrometry and external beam particle-induced X-ray emission and the results were utilized in the construction of multilayer optical models for the evaluation and interpretation of the spectroellipsometric measurements.

  7. JINR test facility for studies FEL bunching technique for CLIC driving beam

    SciTech Connect

    Dolbilov, G.V.; Fateev, A.A.; Ivanov, I.N.

    1995-12-31

    SILUND-21 linear induction accelerator (energy up to 10 MeV, peak current about of 1 kA, pulse duration 50 - 70 ns) is constructed at JINR in the framework of experimental program to study free electron laser physics, a problem of two-beam acceleration and microwave electronics. In this paper we present project of an experiment to adopt the FEL bunching technique for generation of the CLIC driving beam.

  8. Vibrational lifetimes of protein amide modes

    SciTech Connect

    Peterson, K.A.; Rella, C.A.

    1995-12-31

    Measurement of the lifetimes of vibrational modes in proteins has been achieved with a single frequency infrared pump-probe technique using the Stanford Picosecond Free-electron Laser, These are the first direct measurements of vibrational dynamics in the polyamide structure of proteins. In this study, modes associated with the protein backbone are investigated. Results for the amide I band, which consists mainly of the stretching motion of the carbonyl unit of the amide linkage, show that relaxation from the first vibrational excited level (v=1) to the vibrational ground state (v=0) occurs within 1.5 picoseconds with apparent first order kinetics. Comparison of lifetimes for myoglobin and azurin, which have differing secondary structures, show a small but significant difference. The lifetime for the amide I band of myoglobin is 300 femtoseconds shorter than for azurin. Further measurements are in progress on other backbone vibrational modes and on the temperature dependence of the lifetimes. Comparison of vibrational dynamics for proteins with differing secondary structure and for different vibrational modes within a protein will lead to a greater understanding of energy transfer and dissipation in biological systems. In addition, these results have relevance to tissue ablation studies which have been conducted with pulsed infrared lasers. Vibrational lifetimes are necessary for calculating the rate at which the energy from absorbed infrared photons is converted to equilibrium thermal energy within the irradiated volume. The very fast vibrational lifetimes measured here indicate that mechanisms which involve direct vibrational up-pumping of the amide modes with consecutive laser pulses, leading to bond breakage or weakening, are not valid.

  9. Note: High density pulsed molecular beam for cold ion chemistry.

    PubMed

    Kokish, M G; Rajagopal, V; Marler, J P; Odom, B C

    2014-08-01

    A recent expansion of cold and ultracold molecule applications has led to renewed focus on molecular species preparation under ultrahigh vacuum conditions. Meanwhile, molecular beams have been used to study gas phase chemical reactions for decades. In this paper, we describe an apparatus that uses pulsed molecular beam technology to achieve high local gas densities, leading to faster reaction rates with cold trapped ions. We characterize the beam's spatial profile using the trapped ions themselves. This apparatus could be used for preparation of molecular species by reactions requiring excitation of trapped ion precursors to states with short lifetimes or for obtaining a high reaction rate with minimal increase of background chamber pressure.

  10. Note: High density pulsed molecular beam for cold ion chemistry

    SciTech Connect

    Kokish, M. G.; Rajagopal, V.; Marler, J. P.; Odom, B. C.

    2014-08-15

    A recent expansion of cold and ultracold molecule applications has led to renewed focus on molecular species preparation under ultrahigh vacuum conditions. Meanwhile, molecular beams have been used to study gas phase chemical reactions for decades. In this paper, we describe an apparatus that uses pulsed molecular beam technology to achieve high local gas densities, leading to faster reaction rates with cold trapped ions. We characterize the beam's spatial profile using the trapped ions themselves. This apparatus could be used for preparation of molecular species by reactions requiring excitation of trapped ion precursors to states with short lifetimes or for obtaining a high reaction rate with minimal increase of background chamber pressure.

  11. Chemotherapy-related neuropathic symptoms and functional impairment in adult survivors of extracranial solid tumors of childhood: Results from the St. Jude Lifetime Cohort Study

    PubMed Central

    Ness, Kirsten K.; Jones, Kendra E.; Smith, Webb A.; Spunt, Sheri L.; Wilson, Carmen L.; Armstrong, Gregory T.; Srivastava, Deo Kumar; Robison, Leslie L.; Hudson, Melissa M.; Gurney, James G.

    2014-01-01

    Objective To ascertain prevalence of peripheral sensory and motor neuropathy; to evaluate impairments in relation to function. Design St. Jude Lifetime Cohort Study, a clinical follow-up study designed to evaluate adverse late effects in adult survivors of childhood cancer. Setting St. Jude Children’s Research Hospital (SJCRH). Participants Eligibility required treatment for an extracranial solid malignancy between 1962 and 2002, age ≥18 years, ≥10 years post-diagnosis, no history of cranial radiation. 531 survivors were included in the evaluation: median age 32 years, median time from diagnosis 25 years. Interventions Not applicable. Main Outcome Measures Primary exposure measures were cumulative doses of vinca-alkaloid and platinum-based chemotherapies. Survivors with scores ≥ 1 on the sensory subscale of the modified Total Neuropathy Score were classified with prevalent sensory impairment. Those with sex-specific Z-scores of ≤−1.3 for dorsiflexion strength were classified with prevalent motor impairment. Participants completed the 6-minute walk test (endurance), the timed up and go test (mobility), and the sensory organization test (balance). Results The prevalence of sensory and motor impairment was 20% and 17.5%, respectively. Vinca-alkaloid exposure was associated with an increased risk of motor impairment (adjusted odds ratio (OR)=1.66, 95% Confidence Interval (CI): 1.04–2.64) without evidence for a dose response. Platinum exposure was associated with increased risk of sensory impairment (adjusted OR= 1.62, 95% CI: 0.97–2.72) without evidence of a dose response. Sensory impairment was associated with poor endurance (OR=1.99, 95% CI: 0.99–4.00) and mobility (OR=1.65, 95% CI: 0.96–2.83). Conclusion Vincristine and cisplatin exposure may increase risk for long-term motor and sensory impairment, respectively. Survivors with sensory impairment are at increased risk for functional performance limitations. PMID:23537607

  12. Laser ion acceleration toward future ion beam cancer therapy - Numerical simulation study -

    PubMed Central

    Kawata, Shigeo; Izumiyama, Takeshi; Nagashima, Toshihiro; Takano, Masahiro; Barada, Daisuke; Kong, Qing; Gu, Yan Jun; Wang, Ping Xiao; Ma, Yan Yun; Wang, Wei Min

    2013-01-01

    Background: Ion beam has been used in cancer treatment, and has a unique preferable feature to deposit its main energy inside a human body so that cancer cell could be killed by the ion beam. However, conventional ion accelerator tends to be huge in its size and its cost. In this paper a future intense-laser ion accelerator is proposed to make the ion accelerator compact. Subjects and methods: An intense femtosecond pulsed laser was employed to accelerate ions. The issues in the laser ion accelerator include the energy efficiency from the laser to the ions, the ion beam collimation, the ion energy spectrum control, the ion beam bunching and the ion particle energy control. In the study particle computer simulations were performed to solve the issues, and each component was designed to control the ion beam quality. Results: When an intense laser illuminates a target, electrons in the target are accelerated and leave from the target; temporarily a strong electric field is formed between the high-energy electrons and the target ions, and the target ions are accelerated. The energy efficiency from the laser to ions was improved by using a solid target with a fine sub-wavelength structure or by a near-critical density gas plasma. The ion beam collimation was realized by holes behind the solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching were successfully realized by a multi-stage laser-target interaction. Conclusions: The present study proposed a novel concept for a future compact laser ion accelerator, based on each component study required to control the ion beam quality and parameters. PMID:24155555

  13. Precision lifetime measurements by single-proton counting

    SciTech Connect

    Young, L.; Hill, W.T. III; Leone, S.R.

    1995-08-01

    There is renewed interest in the accurate measurement of lifetimes of excited states in alkalis in order to test ab initio theories which are needed for the interpretation of atomic parity nonconservation measurements. While it is often assumed that the fast-beam laser method yields the most accurate lifetimes, we demonstrated that an alternative technique, time-correlated single-photon counting, is capable of achieving comparable accuracy. Using this method at JILA, we measured the lifetimes of the 6p {sup 2}p{sub 1/2} and 6p {sup 2}P{sub 3/2} levels in atomic Cs with accuracies {approx}0.2-0.3%. A high-repetition rate, femtosecond, self-modelocked Ti:sapphire laser is used to excite Cs produced in a well-collimated atomic beam. The time interval between the excitation pulse and the arrival of a fluorescence photon is measured repetitively until the desired statistics are obtained. The lifetime results are 34.75(7) ns and 30.41(10) ns for the 6p {sup 2}P{sub 1/2} and 6p {sup 2}P{sub 3/2} levels, respectively. These lifetimes are in agreement with those extracted from ab initio many-ody perturbation theory calculations at the sub 1% level. The measurement errors are dominated by systematic effects, and methods to alleviate these and approach an accuracy of 0.1% were determined.

  14. Optical studies on electron beam evaporated lithium triborate films.

    PubMed

    Mohandoss, R; Dhanuskodi, S; Sanjeeviraja, C

    2012-10-01

    Lithium triborate (LB3) has numerous applications in scintillator for neutron detection, laser weapon and communication. LB3 films have been prepared by electron beam evaporation technique under a pressure of 1×10(-5) mbar on glass substrate at 323 K for 4 min. The crystallographic orientations and the lattice parameters (a=8.55 (2); b=5.09 (2); c=7.39 (2)Å) were determined by powder XRD indicating the (111) preferential orientation of the film. The lower cut off wavelength at 325 nm with 75% transparency was measured from the UV-vis spectrum. The optical constants extinction coefficient (K), reflectance (R), the linear refractive index (1.34) and the optical energy band gap (~4.0 eV) were estimated. The photoluminescence spectrum shows the emission peak in the visible region with low concentration of oxygen defects. LB3 is found to be second harmonic generation (SHG) active using a Q-switched Nd:YAG laser (1064 nm, 9 ns, 10 Hz). The nonlinear refractive index (n(2)~10(-16) cm(2)/W) and nonlinear absorption coefficient (β~10(-2) cm/W) reveal (Z-scan technique) that the material has negative nonlinearity and self-focusing nature. PMID:22925906

  15. Ion Beam Analyses Of Bark And Wood In Environmental Studies

    NASA Astrophysics Data System (ADS)

    Lill, J.-O.; Saarela, K.-E.; Harju, L.; Rajander, J.; Lindroos, A.; Heselius, S.-J.

    2011-06-01

    A large number of wood and bark samples have been analysed utilizing particle-induced X-ray emission (PIXE) and particle-induced gamma-ray emission (PIGE) techniques. Samples of common tree species like Scots Pine, Norway Spruce and birch were collected from a large number of sites in Southern and Southwestern Finland. Some of the samples were from a heavily polluted area in the vicinity of a copper-nickel smelter. The samples were dry ashed at 550 °C for the removal of the organic matrix in order to increase the analytical sensitivity of the method. The sensitivity was enhanced by a factor of 50 for wood and slightly less for bark. The ashed samples were pressed into pellets and irradiated as thick targets with a millimetre-sized proton beam. By including the ashing procedure in the method, the statistical dispersion due to elemental heterogeneities in wood material could be reduced. As a by-product, information about the elemental composition of ashes was obtained. By comparing the concentration of an element in bark ash to the concentration in wood ash of the same tree useful information from environmental point of view was obtained. The obtained ratio of the ashes was used to distinguish between elemental contributions from anthropogenic atmospheric sources and natural geochemical sources, like soil and bedrock.

  16. Optical studies on electron beam evaporated Lithium Triborate films

    NASA Astrophysics Data System (ADS)

    Mohandoss, R.; Dhanuskodi, S.; Sanjeeviraja, C.

    2012-10-01

    Lithium triborate (LB3) has numerous applications in scintillator for neutron detection, laser weapon and communication. LB3 films have been prepared by electron beam evaporation technique under a pressure of 1 × 10-5 mbar on glass substrate at 323 K for 4 min. The crystallographic orientations and the lattice parameters (a = 8.55 (2); b = 5.09 (2); c = 7.39 (2) Å) were determined by powder XRD indicating the (1 1 1) preferential orientation of the film. The lower cut off wavelength at 325 nm with 75% transparency was measured from the UV-vis spectrum. The optical constants extinction coefficient (K), reflectance (R), the linear refractive index (1.34) and the optical energy band gap (˜4.0 eV) were estimated. The photoluminescence spectrum shows the emission peak in the visible region with low concentration of oxygen defects. LB3 is found to be second harmonic generation (SHG) active using a Q-switched Nd:YAG laser (1064 nm, 9 ns, 10 Hz). The nonlinear refractive index (n2 ˜ 10-16 cm2/W) and nonlinear absorption coefficient (β ˜ 10-2 cm/W) reveal (Z-scan technique) that the material has negative nonlinearity and self-focusing nature.

  17. Numerical studies of the Weibel Instability in Intense Charged Particle Beams with Large Energy Anisotropy

    NASA Astrophysics Data System (ADS)

    Lee, Wei-Li; Startsev, Edward A.; Davidson, Ronald C.

    2004-11-01

    In intense charged particle beams with large temperature anisotropy free energy is available to drive a transverse electromagnetic Weibel-type instability. The finite transverse geometry of the confined beam makes a detailed theoretical investigation difficult. In this paper the newly developed bEASt (beam eigenmode and spectra) code which solves the linearized Vlasov-Maxwell equations is used to investigate the detailed properties of the Weibel instability for a long charge bunch propagating through a cylindrical pipe of radius r_w. The stability analysis is carried out for azimuthally symmetric perturbations about a two-temperature thermal equilibrium distribution in the smooth-focusing approximation. To study the nonlinear stage of the instability, the Darwin model is being developed and incorporated into the Beam Equilibrium Stability and Transport(BEST) code.

  18. Studies of the effects of electron cloud formation on beam dynamics at CesrTA

    SciTech Connect

    Crittenden, J. A.; Calvey, J. R.; Dugan, G.; Livezey, J. A.; Kreinick, D.L.; Palmer, M. A.; Rubin, D. L.; Harkay, K.; Holtzapple, R. L.; Ohmi, K.; Furman, M. A.; Penn, G.; Venturini, M.; Pivi, M. T. F.; Wang, L.

    2009-05-01

    The Cornell Electron Storage Ring Test Accelerator (CesrTA) has commenced operation as a linear collider damping ring test bed following its conversion from an e{sup +}e{sup -}-collider in 2008. A core component of the research program is the measurement of effects of synchrotron-radiation-induced electron cloud formation on beam dynamics. We have studied the interaction of the beam with the cloud with measurements of coherent tune shifts and emittance growth in various bunch train configurations, bunch currents, beam energies, and bunch lengths, for both e{sup +} and e{sup -} beams. This paper compares a subset of these measurements to modeling results from the two-dimensional cloud simulation packages ECLOUD and POSINST. These codes each model most of the tune shift measurements with remarkable accuracy, while some comparisons merit further investigation.

  19. Experimental study of ultrasonic beam sectors for energy conversion into Lamb waves and Rayleigh waves.

    PubMed

    Declercq, Nico Felicien

    2014-02-01

    When a bounded beam is incident on an immersed plate Lamb waves or Rayleigh waves can be generated. Because the amplitude of a bounded beam is not constant along its wave front, a specific beam profile is formed that influences the local efficiency of energy conversion of incident sound into Lamb waves or Rayleigh waves. Understanding this phenomenon is important for ultrasonic immersion experiments of objects because the quality of such experiments highly depends on the amount of energy transmitted into the object. This paper shows by means of experiments based on monochromatic Schlieren photography that the area within the bounded beam responsible for Lamb wave generation differs from that responsible for Rayleigh wave generation. Furthermore it provides experimental verification of an earlier numerical study concerning Rayleigh wave generation.

  20. Lifetime Occupational Physical Activity and Musculoskeletal Aging in Middle-Aged Men and Women in Denmark: Retrospective Cohort Study Protocol and Methods

    PubMed Central

    Mortensen, Ole Steen; Reventlow, Susanne; Skov, Peder Georg; Andersen, Johan Hviid; Rubak, Tine Steen; Hansen, Åse Marie; Andersen, Lars L; Lund, Rikke; Osler, Merete; Christensen, Ulla; Avlund, Kirsten

    2012-01-01

    Background Physical function is essential for performing most aspects of daily life and musculoskeletal aging leads to a decline in physical function. The onset and rate of this process vary and are influenced by environmental, genetic, and hormonal factors. Although everyone eventually experiences musculoskeletal aging, it is beneficial to study the factors that influence the aging process in order to prevent disability. The role of occupational physical activity in the musculoskeletal aging process is unclear. In the past, hard physical work was thought to strengthen the worker, but current studies in this field fail to find a training effect in jobs with a high level of occupational physical activity. Objective The aim of this study is to examine the influence of lifetime occupational physical activity on physical function in midlife. The study follows the “occupational life-course perspective,” emphasizing the importance of occupational exposures accumulated throughout life on the musculoskeletal aging process taking socioeconomic and lifestyle factors into consideration. Methods This study is a retrospective cohort study including a cross-sectional measurement of physical function in 5000 middle-aged Danes. Data was obtained from the Copenhagen Aging and Midlife Biobank (CAMB) which is based on three existing Danish cohorts. Using questionnaire information about the five longest-held occupations, the job history was coded from the Danish version of the International Standard Classification of Occupations (D-ISCO 88) and a job exposure matrix containing information about occupational physical activity in Danish jobs was applied to the dataset. The primary outcomes are three tests of physical function: handgrip strength, balance, and chair rise. In the analyses, we will compare physical function in midlife according to accumulated exposure to high levels of occupational physical activity. Conclusions We have a unique opportunity to study the influence of

  1. Lifetime tests for MAC vertex chamber

    SciTech Connect

    Nelson, H.N.

    1986-07-01

    A vertex chamber for MAC was proposed to increase precision in the measurement of the B hadron and tau lepton lifetimes. Thin-walled aluminized mylar drift tubes were used for detector elements. A study of radiation hardness was conducted under the conditions of the proposed design using different gases and different operating conditions. (LEW)

  2. Radiative lifetimes in Co I

    NASA Astrophysics Data System (ADS)

    Nitz, D. E.; Bergeson, S. D.; Lawler, J. E.

    1995-03-01

    New radiative-lifetime measurements based on time-resolved laser-induced fluorescence are reported for 133 odd-parity and 2 even-parity levels of Co I, ranging in energy from 28300 to 59400 cm-1. Our lifetimes agree with earlier, but much less extensive, lifetime measurements based on laser-induced fluorescence. Satisfactory agreement is also found with the critical compilation of atomic transition probabilities from the U.S. National Bureau of Standards [J. Phys. Chem. Ref. Data 17, Suppl 4 (1988)]. Our measurements provide a reliable absolute normalization for a much more comprehensive determination of Co I atomic transition probabilities.

  3. Study on vibrational relaxation dynamics of phenol-water complex by picosecond time-resolved IR-UV pump-probe spectroscopy in a supersonic molecular beam

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yasunori; Inokuchi, Yoshiya; Ebata, Takayuki; Petković, Milena

    2013-06-01

    A comparative study of vibrational energy relaxation (VER) between the monohydrated complexes of phenol-d0 and phenol-d1 is investigated in a supersonic molecular beam. The direct time-resolved measurement of energy redistribution from the phenolic OH/OD stretching mode of the phenol-d0-H2O/phenol-d1-D2O is performed by picosecond IR-UV pump-probe spectroscopy. Two complexes follow the same relaxation process that begins with the intramolecular vibrational energy redistribution (IVR) and the intermolecular vibrational energy redistribution (IVR), which is followed by the vibrational predissociation (VP). The difference in the relaxation lifetimes between them is discussed by anharmonic force field and RRKM calculations. Anharmonic analysis implies that intra- (IVR) and intermolecular (IVR) relaxations occur in parallel in the complexes. The RRKM-predicted dissociation (VP) lifetimes show qualitative agreement with the observed results, suggesting that VP takes place after the statistical energy distribution in the complexes.

  4. A measurement of the tau lepton lifetime at ARGUS

    NASA Astrophysics Data System (ADS)

    Saull, Patrick Richard Behrendt

    Data taken with the ARGUS detector at DESY, Hamburg, specifically toverlinetoverline pairs produced from e+e - collisions in the energy range (10.4-10.6)GeV, are used to make a precision measurement of the tau lifetime. A new method is introduced which is independent of the beam position and envelope, and applicable to tau events having one-three topology. Applied to ARGUS data the method yields a value for the tau lifetime of tt=287+/-11(st atistical)+/-8(systemat ic)fs.

  5. Measurement of Metastable Lifetimes of Highly-Charged Ions

    NASA Technical Reports Server (NTRS)

    Smith, Steven J.; Chutjian, A.; Lozano, J.

    2002-01-01

    The present work is part of a series of measurements of metastable lifetimes of highly-charged ions (HCIs) which contribute to optical absorption, emission and energy balance in the Interstellar Medium (ISM), stellar atmospheres, etc. Measurements were carried out using the 14-GHz electron cyclotron resonance ion source (ECRIS) at the JPL HCI facility. The ECR provides useful currents of charge states such as C(sup(1-6)+), Mg(sup(1-6)+) and Fe(sup(1-17)+). In this work the HCI beam is focused into a Kingdon electrostatic ion trap for measuring lifetimes via optical decays.

  6. On sunspot and starspot lifetimes

    SciTech Connect

    Bradshaw, S. J.; Hartigan, P. E-mail: hartigan@sparky.rice.edu

    2014-11-01

    We consider the lifetimes of spots on the Sun and other stars from the standpoint of magnetic diffusion. While normal magnetic diffusivity predicts lifetimes of sunspots that are too large by at least two orders of magnitude, turbulent magnetic diffusivity accounts for both the functional form of the solar empirical spot-lifetime relation and for the observed sunspot lifetimes, provided that the relevant diffusion length is the supergranule size. Applying this relation to other stars, the value of turbulent diffusivity depends almost entirely on supergranule size, with very weak dependence on other variables such as magnetic field strength and density. Overall, the best observational data for other stars is consistent with the extension of the solar relation, provided that stellar supergranule sizes for some stars are significantly larger than they are on the Sun.

  7. Measurement of the tau lifetime

    SciTech Connect

    Jaros, J.A.

    1982-10-01

    If the tau lepton couples to the charged weak current with universal strength, its lifetime can be expressed in terms of the muon's lifetime, the ratio of the masses of the muon and the tau, and the tau's branching ratio into e anti nu/sub e/ nu/sub tau/ as tau/sub tau/ = tau/sub ..mu../ (m/sub ..mu..//m/sub tau/)/sup 5/ B(tau ..-->.. e anti nu/sub e/nu/sub tau/) = 2.8 +- 0.2 x 10/sup -13/ s. This paper describes the measurement of the tau lifetime made by the Mark II collaboration, using a new high precision drift chamber in contunction with the Mark II detector at PEP. The results of other tau lifetime measurements are summarized.

  8. Ion transport studies on the PLT tokamak during neutral beam injection

    SciTech Connect

    Suckewer, S.; Cavallo, A.; Cohen, S.; Daughney, C.; Denne, B.; Hinnov, E.; Hosea, J.; Hulse, R.; Hwang, D.; Schilling, G.

    1983-12-01

    Radial transport of ions during co- and counter-neutral beam heating in the PLT tokamak has been studied, using molybdenum and scandium ions as tracer elements. The time evolution of the radial profiles of several ionization stages of both elements, injected by laser blowoff during the neutral beam heating, were measured under three significantly different beam-plasma combinations. No noticeable differences in the radial profiles attributable to the beam direction were observed. However, a given injected amount resulted in considerably larger interior concentrations of the tracer element in the counter-beam heating cases, suggesting larger penetration of the plasma periphery. Computer simulation with the MIST code suggests a net inward drift of the order 10/sup 3/ cm/sec superposed to a diffusion coefficient of the order 10/sup 4/ cm/sup 2//sec for both scandium and molybdenum ions. Injection of larger amounts of the tracer element, sufficient to cause measurable central electron temperature changes, resulted in dramatic changes in ion-state distributions, making some appear peaked in the center while others disappeared. This effect could be produced with both co- and counter-beam heating, but with lesser amounts in the latter case. It is interpreted as rearrangement of the ionization balance, rather than any preferential accumulation of the injected element.

  9. Emission Lifetimes of a Fluorescent Dye under Shock Compression.

    PubMed

    Liu, Wei-long; Bassett, Will P; Christensen, James M; Dlott, Dana D

    2015-11-01

    The emission lifetimes of rhodamine 6G (R6G) were measured under shock compression to 9.1 GPa, with the dual intents of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly(methyl methacrylate) (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and the emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0 to 9 GPa, with a slope of -0.22 ns·GPa(-1). The linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, because lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure.

  10. Emission Lifetimes of a Fluorescent Dye under Shock Compression.

    PubMed

    Liu, Wei-long; Bassett, Will P; Christensen, James M; Dlott, Dana D

    2015-11-01

    The emission lifetimes of rhodamine 6G (R6G) were measured under shock compression to 9.1 GPa, with the dual intents of better understanding molecular photophysics in extreme environments and assessing the usefulness of fluorescence lifetime microscopy to measure spatially dependent pressure distributions in shocked microstructured media. R6G was studied as free dye dissolved in poly(methyl methacrylate) (PMMA), or dye encapsulated in silica microparticles suspended in PMMA. Thin layers of these materials in impedance-matched geometries were subjected to planar single-stage shocks created by laser-driven flyer plates. A synchronized femtosecond laser excited the dye at selected times relative to flyer plate arrival and the emission lifetimes were measured with a streak camera. Lifetimes decreased when shocks arrived. The lifetime decrease was attributed to a shock-induced enhancement of R6G nonradiative relaxation. At least part of the relaxation involved shock-enhanced intersystem crossing. For free dye in PMMA, the lifetime decrease during the shock was shown to be a linear function of shock pressure from 0 to 9 GPa, with a slope of -0.22 ns·GPa(-1). The linear relationship makes it simple to convert lifetimes into pressures. Lifetime measurements in shocked microenvironments may be better than emission intensity measurements, because lifetimes are sensitive to the surrounding environment, but insensitive to intensity variations associated with the motion and optical properties of a dynamically changing structure. PMID:26469397

  11. Design study of low energy beam transport line for ion beams of the post-accelerator at RAON

    NASA Astrophysics Data System (ADS)

    Lee, Yumi; Kim, Eun-San

    2015-07-01

    Low-energy ions produced by the ion source pass through the focusing and acceleration sections. During this process, the ions accumulate energy and are finally transported to the apparatus that utilizes them for a specific purpose. Thus, in order to increase the transmission efficiency of the ion beams, the low energy beam transport (LEBT) system must minimize the beam loss and the emittance growth. The LEBT system is designed and optimized to transmit 132Sn16+ and 58Ni8+ beams of the post-accelerator at RAON that is the accelerator complex for the rare isotope science. The post-accelerator LEBT line comprises solenoids and electrostatic quadrupoles for transverse focusing and a multi-harmonic buncher for longitudinal focusing. This paper presents the results of the optical design and beam tracking for the post-accelerator LEBT obtained by using TraceWIN and TRACK codes.

  12. Molecular Beam Studies of Hot Atom Chemical Reactions: Reactive Scattering of Energetic Deuterium Atoms

    DOE R&D Accomplishments Database

    Continetti, R. E.; Balko, B. A.; Lee, Y. T.

    1989-02-01

    A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H{sub 2} -> DH + H and the substitution reaction D + C{sub 2}H{sub 2} -> C{sub 2}HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible.

  13. Nuclear Astrophysical studies using low-energy RI beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Wakabayashi, Y.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kurihara, Y.; Kubono, S.; Teranishi, T.; He, J. J.; Kwon, Y. K.; Nishimura, S.; Togano, Y.; Iwasa, N.; Niikura, M.; Khiem, L. H.

    2009-05-01

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo, used for various studies covering nuclear-astrophysical topics. An application of the RI beam at CRIB for the astrophysical studies is a new measurement of the proton resonance scattering on 7Be. The measurement was performed up to the excitation energy of 6.8 MeV, ans the excitation function above 3.5 MeV was successfully measured for the first time, providing important information about the reaction rate of 7Be(p,γ)8B, which is the key reaction in the solar 8B neutrino production. A preliminary result of the 7Be+p experiment is presented.

  14. Nuclear Astrophysical studies using low-energy RI beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Wakabayashi, Y.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kurihara, Y.; Kubono, S.; Niikura, M.; Teranishi, T.; He, J. J.; Kwon, Y. K.; Nishimura, S.; Togano, Y.; Iwasa, N.; Khiem, L. H.

    2009-05-04

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo, used for various studies covering nuclear-astrophysical topics. An application of the RI beam at CRIB for the astrophysical studies is a new measurement of the proton resonance scattering on {sup 7}Be. The measurement was performed up to the excitation energy of 6.8 MeV, ans the excitation function above 3.5 MeV was successfully measured for the first time, providing important information about the reaction rate of {sup 7}Be(p,{gamma}){sup 8}B, which is the key reaction in the solar {sup 8}B neutrino production. A preliminary result of the {sup 7}Be+p experiment is presented.

  15. Moisture determination in composite materials using positron lifetime techniques

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Holt, W. R.; Mock, W., Jr.

    1980-01-01

    A technique was developed which has the potential of providing information on the moisture content as well as its depth in the specimen. This technique was based on the dependence of positron lifetime on the moisture content of the composite specimen. The positron lifetime technique of moisture determination and the results of the initial studies are described.

  16. Experimental Investigation of Excited-State Lifetimes in Atomic Ytterbium

    SciTech Connect

    Bowers, C.J.; Budker, D.; Commins, E.D.; DeMille, D.; Freedman, S.J.; Nguyen, A.-T.; Shang, S.-Q.; Zolotorev, M.; /SLAC

    2011-11-15

    Lifetimes of 21 excited states in atomic Yb were measured using time-resolved fluorescence detection following pulsed laser excitation. The lifetime of the 4f{sup 14}5d6s {sup 3}D{sub 1} state, which is of particular importance for a proposed study of parity nonconservation in atoms, was measured to be 380(30) ns.

  17. Estimating the volcanic emission rate and atmospheric lifetime of SO2 from space: a case study for Kīlauea volcano, Hawai'i

    USGS Publications Warehouse

    Beirle, Steffen; Hörmann, Christoph; Penning de Vries, Malouse; Dörner, Stefan; Kern, Christoph; Wagner, Thomas

    2014-01-01

    We present an analysis of SO2 column densities derived from GOME-2 satellite measurements for the Kīlauea volcano (Hawai`i) for 2007–2012. During a period of enhanced degassing activity in March–November 2008, monthly mean SO2 emission rates and effective SO2 lifetimes are determined simultaneously from the observed downwind plume evolution and meteorological wind fields, without further model input. Kīlauea is particularly suited for quantitative investigations from satellite observations owing to the absence of interfering sources, the clearly defined downwind plumes caused by steady trade winds, and generally low cloud fractions. For March–November 2008, the effective SO2 lifetime is 1–2 days, and Kīlauea SO2 emission rates are 9–21 kt day−1, which is about 3 times higher than initially reported from ground-based monitoring systems.

  18. Study on efficiency droop in InGaN/GaN light-emitting diodes based on differential carrier lifetime analysis

    NASA Astrophysics Data System (ADS)

    Meng, Xiao; Wang, Lai; Hao, Zhibiao; Luo, Yi; Sun, Changzheng; Han, Yanjun; Xiong, Bing; Wang, Jian; Li, Hongtao

    2016-01-01

    Efficiency droop is currently one of the most popular research problems for GaN-based light-emitting diodes (LEDs). In this work, a differential carrier lifetime measurement system is optimized to accurately determine carrier lifetimes (τ) of blue and green LEDs under different injection current (I). By fitting the τ-I curves and the efficiency droop curves of the LEDs according to the ABC carrier rate equation model, the impact of Auger recombination and carrier leakage on efficiency droop can be characterized simultaneously. For the samples used in this work, it is found that the experimental τ-I curves cannot be described by Auger recombination alone. Instead, satisfactory fitting results are obtained by taking both carrier leakage and carriers delocalization into account, which implies carrier leakage plays a more significant role in efficiency droop at high injection level.

  19. Studying thin film damping in a micro-beam resonator based on non-classical theories

    NASA Astrophysics Data System (ADS)

    Ghanbari, Mina; Hossainpour, Siamak; Rezazadeh, Ghader

    2016-06-01

    In this paper, a mathematical model is presented for studying thin film damping of the surrounding fluid in an in-plane oscillating micro-beam resonator. The proposed model for this study is made up of a clamped-clamped micro-beam bound between two fixed layers. The micro-gap between the micro-beam and fixed layers is filled with air. As classical theories are not properly capable of predicting the size dependence behaviors of the micro-beam, and also behavior of micro-scale fluid media, hence in the presented model, equation of motion governing longitudinal displacement of the micro-beam has been extracted based on non-local elasticity theory. Furthermore, the fluid field has been modeled based on micro-polar theory. These coupled equations have been simplified using Newton-Laplace and continuity equations. After transforming to non-dimensional form and linearizing, the equations have been discretized and solved simultaneously using a Galerkin-based reduced order model. Considering slip boundary conditions and applying a complex frequency approach, the equivalent damping ratio and quality factor of the micro-beam resonator have been obtained. The obtained values for the quality factor have been compared to those based on classical theories. We have shown that applying non-classical theories underestimate the values of the quality factor obtained based on classical theories. The effects of geometrical parameters of the micro-beam and micro-scale fluid field on the quality factor of the resonator have also been investigated.

  20. Analysis of positron lifetime spectra in polymers

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Mall, Gerald H.; Sprinkle, Danny R.

    1988-01-01

    A new procedure for analyzing multicomponent positron lifetime spectra in polymers was developed. It requires initial estimates of the lifetimes and the intensities of various components, which are readily obtainable by a standard spectrum stripping process. These initial estimates, after convolution with the timing system resolution function, are then used as the inputs for a nonlinear least squares analysis to compute the estimates that conform to a global error minimization criterion. The convolution integral uses the full experimental resolution function, in contrast to the previous studies where analytical approximations of it were utilized. These concepts were incorporated into a generalized Computer Program for Analyzing Positron Lifetime Spectra (PAPLS) in polymers. Its validity was tested using several artificially generated data sets. These data sets were also analyzed using the widely used POSITRONFIT program. In almost all cases, the PAPLS program gives closer fit to the input values. The new procedure was applied to the analysis of several lifetime spectra measured in metal ion containing Epon-828 samples. The results are described.