Science.gov

Sample records for beam lifetime studies

  1. Some results of the advanced photon source beam lifetime studies

    SciTech Connect

    Bizek, H.M.

    1997-06-01

    Total beam lifetime consists of two components: the residual-gas-scattering lifetime and Touschek lifetime. The residual-gas lifetime is comprised of the elastic and inelastic scattering on electrons and elastic and inelastic scattering on nuclei. Touschek scattering involves scattering of particles within the bunch. One usually calculates only the elastic scattering on nuclei (single Coulomb scattering) and inelastic scattering on nuclei (bremsstrahlung) of the residual-gas-scattering lifetime component. Experience gained from computing the beam lifetime in the Advanced Photon Source (APS) storage ring shows that the electron scattering should not be neglected, particularly the inelastic contribution. Given the measured quantities from the APS storage ring, one can compare theoretical predictions with experimental results. Uncertainties in calculating the various contributions to lifetime will be discussed.

  2. Beam lifetime study based on momentum acceptance restriction by movable beam scraper

    NASA Astrophysics Data System (ADS)

    Kaneyasu, T.; Takabayashi, Y.; Iwasaki, Y.; Koda, S.

    2012-12-01

    The beam lifetime of the SAGA-LS electron storage ring was experimentally investigated using a movable beam scraper installed in a dispersive section. In addition to physical aperture restriction, the scraper could be used to reduce the momentum acceptance of the storage ring, enabling the evaluation of the Touschek effect. Lifetime measurements were performed with scraper scans, and the individual contributions of gas scattering and the Touschek effect were clarified. Our results confirm that the present method provides a basic understanding of lifetime limiting effects in the storage ring.

  3. Beam lifetime and beam brightness in ALS

    SciTech Connect

    Kim, C.; Jackson, A.; Warwick, A.

    1995-04-01

    Beam lifetime in ALS is dominated by the Touschek scattering. Measurements of lifetime in single-bunch mode with estimates of bunch dimensions obtained from undulator radiation data are consistent with expectations (t=1.8 hours at 1.25 mA per bunch). However, the lifetime is significantly longer in multi-bunch mode (t=ll hours at 400 mA per 320 bunches). This discrepancy has been traced to an increase in the momentum spread and bunch length in the beam caused by longitudinal coupled-bunch motions driven by higher-order modes in the rf cavities. The increased momentum spread leads to a significant degradation in the undulator spectral performance. Feedback stabilization of the coupled-bunch motion improves the spectral characteristics of the undulator beam at the expense of beam lifetime. We observe an increase of {approximately}200% in beam lifetime by operating at the betatron coupling resonance.

  4. Electron beam induced microstructural changes and electrical conductivity in Bakelite polymer RPC detector material: A positron lifetime study

    NASA Astrophysics Data System (ADS)

    Aneesh Kumar, K. V.; Ningaraju, S.; Munirathnamma, L. M.; Ravikumar, H. B.; Ranganathaiah, C.

    2015-06-01

    In order to explore the structural modification induced electrical conductivity, samples of Bakelite RPC polymer detector materials were exposed to 8 MeV of electron beam with the irradiation dose from 20 kGy to 100 kGy in steps of 20 kGy. The microstructural changes upon electron beam irradiation have been studied using Positron Annihilation Lifetime Spectroscopy (PALS) and Fourier Transform Infrared (FTIR) Spectroscopy. Positron lifetime parameters viz., o-Ps lifetime and its intensity show chain scission at lower doses (20 kGy, 40 kGy) followed by cross-linking beyond 40 kGydue to the radical reactions. The reduction in electrical conductivity of Bakelite material beyond 60 kGy is correlated to the conducting pathways and cross-links in the polymer matrix. The appropriate doses of electron beam irradiation of Bakelite material may reduce the leakage current and hence improves the performance of the detector.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Effects of vertical aperture on beam lifetime at the Advanced Photon Source (APS) storage ring

    SciTech Connect

    Bizek, H.M.

    1995-06-01

    When a positron`s energy deviation {delta}E/E exceeds the rf acceptance, or when it receives an angular kick for the betatron motion that exceeds some limiting admittance, the positron will be lost. The main contributions to the total beam lifetime come from single Coulomb and Touschek scattering. In this report we investigate the dependence of the residual gas pressure and the vertical aperture of the Advanced Photon Source storage ring on the total beam. lifetime. We present results of calculating the total beam lifetime as a function of vertical aperture for varying average ring pressure, beam current, and coupling coefficient.

  13. Estimations of Beam Lifetimes in the SIS18

    SciTech Connect

    Rumolo, G.; Boine-Frankenheim, O.; Kraemer, A.

    2005-06-08

    The present developments for high current operation with U28+ in the SIS focus on the efficient collimation of projectile stripping losses and on the subsequent pumping of the desorbed molecules. Beside the projectile ionization and beam loss, the desorption induced by residual gas (target) ionization could also play a role in the dynamic vacuum pressure at the typical SIS18 ion beam energies. We describe a simplified model for the dynamic pressure that is based on the estimated and expected desorption yields as well as on the known cross sections for projectile and target ionization. We integrate the model over realistic SIS acceleration ramps and predict the beam life time. From our model we obtain the fractional beam loss under stable (but dynamic) vacuum conditions for different beam ions.

  14. 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.

  15. A code for calculating intrabeam scattering and beam lifetime

    SciTech Connect

    Kim, C.H.

    1997-05-01

    Beam emittances in a circular accelerator with a high beam intensity are strongly affected by the small angle intrabeam Coulomb scattering. In the computer simulation model the authors present here they used three coupled nonlinear differential equations to describe the evolution of the emittances in the transverse and the longitudinal planes. These equations include terms which take into account the intra-beam scattering, adiabatic damping, microwave instabilities, synchrotron damping, and quantum excitations. A code is generated to solve the equations numerically and incorporated into a FORTRAN code library. Circular high intensity physics routines are included in the library such as intrabeam scattering, Touschek scattering, and the bunch lengthening effect of higher harmonic cavities. The code runs presently in the PC environment. Description of the code and some examples are presented.

  16. Lifetime dependence of nitrided carbon stripper foils on sputter angle during N+ ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Sugai, I.; Oyaizu, M.; Takeda, Y.; Kawakami, H.; Kawasaki, K.; Hattori, T.; Kadono, T.

    2015-09-01

    We fabricated high-lifetime thin nitride carbon stripper (NCS) foils with high nitrogen contents using ion-beam sputtering with reactive nitrogen gas and investigated the dependence of their lifetimes on the sputter angle. The nitrogen in carbon foils plays a critical role in determining their lifetime. Therefore, in order to investigate the effects of the nitrogen level in NCS foils on foil lifetime, we measured the sputtering yield for different sputter angles at a sputtering voltage of 10 kV while using carbon-based targets. We also measured the nitrogen-to-carbon thickness ratios of the foils using Rutherford backscattering spectrometry. The foils made at a sputter angle of 15° using a glassy amorphous carbon target exhibited an average increase of 200-fold in lifetime when compared to commercially available foils.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Probing polymeric thin films using beam-based positronium annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Peng, Huagen

    Positrounium annihilation lifetime spectroscopy (PALS) utilizing a focused low energy beam of positrons to control implantation depth enables the analysis of very thin films. Beam-PALS was used to study confinement and interfacial effects on polymer mobility in ultra-thin polycarbonate films and to characterize nanoporous structures of polymeric low dielectric constant (low-k ) thin films. Three complementary techniques were used to address the apparent discrepancies in recent polymer film results. Beam-PALS (probing positronium nanovoid lifetime, tau), specular X-ray reflectivity (SXR, monitoring film thickness, h) and incoherent neutron scattering (INS, characterizing mean-square atomic displacements, ) were combined to study the thermophysical properties of Bisphenol-A polycarbonate (PC) ultra-thin films (60 A to ˜1000 A) supported on an oxidized silicon wafer surface. As h decreased the concomitant reduction in thermal expansion coefficients of h, tau and < u2>, as well as the decreased amplitudes of < u2>, indicated that thin film confinement produces suppressed molecular mobility in PC. These films were modeled with an immobile interface layer ranging from 38 A to 130 A, depending on the measurement technique and the temperature range. No clear trends in the apparent glass transition temperature (Tg) emerged from these techniques, thus rendering Tg shifts inconclusive and of less fundamental importance. Beam-PALS was also applied to characterize several generations of porous SiLK (Trade Mark of Dow Chemical) low-k films to reveal the size, size distribution, interconnectivity and possible morphology of the engineered nanopores. The dependence of these properties on porogen loading/porosity was carefully analyzed and compared, when possible, with results from other techniques such as small-angle X-ray scattering and AFM. Unique to the PALS technique is the ability to quantify the pore interconnection length. Porous SiLK (V9), U.2 and Y were found to have

  4. 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.

  5. Accurate lifetime measurements for the noble gases by the electron beam alignment technique

    NASA Astrophysics Data System (ADS)

    Gorny, M. B.; Kazantsev, S. A.; Matisov, B. G.; Polezhaevs, N. T.

    1985-03-01

    Accurate lifetime measurement for the 41 P 1, 41 D 2, 51 D 2 helium and the atomic 2 p and 3 p states of other noble gases was performed by the low energy electron beam alignment technique. An account of the influence of magnetic field on the electron path was made to obtain the real Hanle signal shape. The influence of the radiation trapping in the collision chamber was analysed with regard to the metastables diffusion. The experimental data were compared with the results of other methods of the lifetime determination.

  6. 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.

  7. 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.

  8. 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.

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

    PubMed

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

    2012-04-01

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm(2) 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/cm(2), 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. 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. PMID:22559528

  10. Source fabrication and lifetime for Li{sup +} ion beams extracted from alumino-silicate sources

    SciTech Connect

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

    2012-04-15

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm{sup 2} have been measured from lithium alumino-silicate ion sources at a temperature of {approx}1275 deg. C. At higher extraction voltages, the source appears to become emission limited with J{>=} 1.5 mA/cm{sup 2}, 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 {approx}40 h at {approx}1275 deg. C, when pulsed at 0.05 Hz and with pulse length of {approx}6 {mu}s 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. 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.

  11. USING A 100 KV DC LOAD LOCK PHOTOGUN TO MEASURE PHOTOCATHODE LIFETIME OF HIGH POLARIZATION STRAINED SUPERLATTICE GAAS/GAASP AT BEAM INTENSITY >1 MILLIAMP

    SciTech Connect

    Joseph Grames; Benard Poelker; Philip Adderley; Joshua Brittian; James Clark; John Hansknecht; Danny Machie; Marcy Stutzman; Kenneth Surles-law; Riad Suleiman

    2007-07-02

    A new GaAs DC high voltage load lock photogun has been constructed at Jefferson Laboratory (JLab), with improved vacuum and photocathode preparation capabilities. As reported previously, this gun was used to study photocathode lifetime with bulk GaAs at DC beam currents between 1 and 10 mA. In this submission, lifetime measurements were performed using high polarization strained-superlattice GaAs photocathode material at beam currents up to 1 mA, with near bandgap light from a fiber based drive laser having picosecond optical pulses and RF time structure.

  12. Electron storage ring beam lifetime dependence on pressure and pumping speed

    SciTech Connect

    Halama, H.J.

    1984-01-01

    The beam loss in electron storage rings depends to a large extent on the interaction of the beam with heavier residual gas molecules such as CO, CO/sub 2/ and A due to Bremsstrahlung and Coulomb scattering. The gas density inside the vacuum chamber is determined by the surface condition of the vacuum chamber which is bombarded by photons (synchrotron radiation) generated by circulating electron beams and by the installed pumping. During the spring shutdown the x-ray ring vacuum system was updated and baked out. Residual gas spectra obtained were typical of a well baked out system, i.e., hydrogen constituted approx. 95% of the gas and the average pressure was in the 10/sup -10/ Torr range. During initial operation the composition of desorbed gases was 43% H/sub 2/, 25% CO and 16% CO/sub 2/ and CH/sub 4/. After 3 months of beam conditioning desorption dropped by a factor of 5 and the CO, CO/sub 2/ and CH/sub 4/ peaks represented smaller percentage of total desorbed gas. Beam lifetime did not, however, show a corresponding increase. The pumping speed of distributed pumps dropped to zero at 1 x 10/sup -9/ Torr pressure but increased rapidly from approx. 20l/s in low 10/sup -9/ as the pressure increased.

  13. Ion Beam Propulsion Study

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Ion Beam Propulsion Study was a joint high-level study between the Applied Physics Laboratory operated by NASA and ASRC Aerospace at Kennedy Space Center, Florida, and Berkeley Scientific, Berkeley, California. The results were promising and suggested that work should continue if future funding becomes available. The application of ion thrusters for spacecraft propulsion is limited to quite modest ion sources with similarly modest ion beam parameters because of the mass penalty associated with the ion source and its power supply system. Also, the ion source technology has not been able to provide very high-power ion beams. Small ion beam propulsion systems were used with considerable success. Ion propulsion systems brought into practice use an onboard ion source to form an energetic ion beam, typically Xe+ ions, as the propellant. Such systems were used for steering and correction of telecommunication satellites and as the main thruster for the Deep Space 1 demonstration mission. In recent years, "giant" ion sources were developed for the controlled-fusion research effort worldwide, with beam parameters many orders of magnitude greater than the tiny ones of conventional space thruster application. The advent of such huge ion beam sources and the need for advanced propulsion systems for exploration of the solar system suggest a fresh look at ion beam propulsion, now with the giant fusion sources in mind.

  14. Minority Carrier Lifetime Studies of Narrow Bandgap Antimonide Superlattices

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    In this study optical modulation response and photoluminescence spectroscopy were used to study mid-wave Ga-free InAs/InAsSb superlattices. The minority carrier lifetimes in the different samples varied from 480 ns to 4700 ns, partly due to different background doping concentrations. It was shown that the photoluminescence intensity can be used as a fast non-destructive tool to predict the material quality. It was also demonstrated that it is crucial to use a low excitation power in the photoluminescence measurements in order to get a good correlation between the photoluminescence intensity and the minority carrier lifetime.

  15. Laboratory study of the cosmic-ray muon lifetime

    NASA Astrophysics Data System (ADS)

    Ward, T.; Barker, M.; Breeden, J.; Komisarcik, K.; Pickar, M.; Wark, D.; Wiggins, J.

    1985-06-01

    The cosmic-ray muon lifetime was measured with a variety of counters designed to study both the free and μ- capture lifetimes. The data were obtained using scintillation detectors and a lead glass detector. These data show the dependence of μ- capture on the atomic number of the chemical element in the detector. The Z dependence of the weak interaction capture process is discussed in terms of the familiar Fermi (ΔJ=0) and Gamow-Teller (ΔJ=1) decays. This experiment was designed for use in advanced undergraduate physics laboratories.

  16. Lifetime Measurements of High Polarization Strained-Superlattice Gallium Arsenide at Beam Current > 1 Milliamp using a New 100kV Load Lock Photogun

    SciTech Connect

    J. M. Grames; P. A. Adderley; J. Brittian; J. Clark; J. Hansknecht; D. Machie; M. Poelker; M. L. Stutzman; R. Suleiman; K. E. L. Surles-Law

    2007-08-01

    A new 100 kV GaAs DC Load Lock Photogun has been constructed at Jefferson Laboratory, with improvements for photocathode preparation and for operation in a high voltage, ultra-high vacuum environment. Although difficult to gauge directly, we believe that the new gun design has better vacuum conditions compared to the previous gun design, as evidenced by longer photocathode lifetime, that is, the amount of charge extracted before the quantum efficiency of the photocathode drops by 1/e of the initial value via the ion back-bombardment mechanism. Photocathode lifetime measurements at DC beam intensity of up to 10 mA have been performed to benchmark operation of the new gun and for fundamental studies of the use of GaAs photocathodes at high average current*. These measurements demonstrate photocathode lifetime longer than one million Coulombs per square centimeter at a beam intensity higher than 1 mA. The photogun has been reconfigured with a high polarization strained superlattice photocathode (GaAs/GaAsP) and a mode-locked Ti:Sapphire laser operating near band-gap. Photocathode lifetime measurements at beam intensity greater than 1 mA are measured and presented for comparison.

  17. Lifetime statistics of quantum chaos studied by a multiscale analysis

    SciTech Connect

    Di Falco, A.; Krauss, T. F.; Fratalocchi, A.

    2012-04-30

    In a series of pump and probe experiments, we study the lifetime statistics of a quantum chaotic resonator when the number of open channels is greater than one. Our design embeds a stadium billiard into a two dimensional photonic crystal realized on a silicon-on-insulator substrate. We calculate resonances through a multiscale procedure that combines energy landscape analysis and wavelet transforms. Experimental data is found to follow the universal predictions arising from random matrix theory with an excellent level of agreement.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Results of head-on beam-beam compensation studies at the Tevatron

    SciTech Connect

    Valishev, A.; Stancari, G.; /Fermilab

    2011-03-01

    At the Tevatron collider, we studied the feasibility of suppressing the antiproton head-on beam-beamtune spread using a magnetically confined 5-keV electron beam with Gaussian transverse profile overlapping with the circulating beam. When electron cooling of antiprotons is applied in regular Tevatron operations, the head-on beam-beam effect on antiprotons is small. Therefore, we first focused on the operational aspects, such as beam alignment and stability, and on fundamental observations of tune shifts, tune spreads, lifetimes, and emittances. We also attempted two special collider stores with only 3 proton bunches colliding with 3 antiproton bunches, to suppress long-range forces and enhance head-on effects. We present here the results of this study and a comparison between numerical simulations and observations, in view of the planned application of this compensation concept to RHIC.

  3. 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.

  4. 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.

  5. 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.

  6. Positron lifetime studies in thermoplastic polyimide test specimens

    NASA Technical Reports Server (NTRS)

    Singh, J. J.; Stclair, T. L.; Holt, W. H.; Mock, W., Jr.

    1982-01-01

    Positron lifetime measurements were made in two thermoplastic polyimide materials recently developed at Langley. The long component lifetime values in polyimidesulfone samples are 847 + or - 81 Ps (dry) and 764 + or - 91 Ps (saturated). The corresponding values in LARC thermoplastic imides are 1080 + or - 139 Ps (dry) and 711 + or - 96 Ps (saturated). Clearly, the presence of moisture has greater effect on positron lifetime in LARC thermoplastic imides than in the case of polyimidesulfones. This result is consistent with the photomicrographic observations made on frozen water saturated specimens of these materials.

  7. Positron annihilation lifetime spectroscopy study of Kapton thin foils

    NASA Astrophysics Data System (ADS)

    Kanda, G. S.; Ravelli, L.; Löwe, B.; Egger, W.; Keeble, D. J.

    2016-01-01

    Variable energy positron annihilation lifetime spectroscopy (VE-PALS) experiments on polyimide material Kapton are reported. Thin Kapton foils are widely used in a variety of mechanical, electronic applications. PALS provides a sensitive probe of vacancy-related defects in a wide range of materials, including open volume in polymers. Varying the positron implantation energy enables direct measurement of thin foils. Thin Kapton foils are also commonly used to enclose the positron source material in conventional PALS measurements performed with unmoderated radionuclide sources. The results of depth-profiled positron lifetime measurements on 7.6 μm and 25 μm Kapton foils are reported and determine a dominant 385(1) ps lifetime component. The absence of significant nanosecond lifetime component due to positronium formation is confirmed.

  8. Positron annihilation lifetime spectroscopy source correction determination: A simulation study

    NASA Astrophysics Data System (ADS)

    Kanda, Gurmeet S.; Keeble, David J.

    2016-02-01

    Positron annihilation lifetime spectroscopy (PALS) can provide sensitive detection and identification of vacancy-related point defects in materials. These measurements are normally performed using a positron source supported, and enclosed by, a thin foil. Annihilation events from this source arrangement must be quantified and are normally subtracted from the spectrum before analysis of the material lifetime components proceeds. Here simulated PALS spectra reproducing source correction evaluation experiments have been systematically fitted and analysed using the packages PALSfit and MELT. Simulations were performed assuming a single lifetime material, and for a material with two lifetime components. Source correction terms representing a directly deposited source and various foil supported sources were added. It is shown that in principle these source terms can be extracted from suitably designed experiments, but that fitting a number of independent, nominally identical, spectra is recommended.

  9. DC photogun vacuum characterization through photocathode lifetime studies

    SciTech Connect

    Marcy Stutzman; Joseph Grames; Matt Poelker; Kenneth Surles-Law; Philip Adderley

    2007-07-02

    Excellent vacuum is essential for long photocathode lifetimes in DC high voltage photoelectron guns. Vacuum Research at Thomas Jefferson National Accelerator Facility has focused on characterizing the existing vacuum systems at the CEBAF polarized photoinjector and on quantifying improvements for new systems. Vacuum chamber preprocessing, full activation of NEG pumps and NEG coating the chamber walls should improve the vacuum within the electron gun, however, pressure measurement is difficult at pressures approaching the extreme-high-vacuum (XHV) region and extractor gauge readings are not significantly different between the improved and original systems. The ultimate test of vacuum in a DC high voltage photogun is the photocathode lifetime, which is limited by the ionization and back-bombardment of residual gasses. Discussion will include our new load-locked gun design as well as lifetime measurements in both our operational and new photo-guns, and the correlations between measured vacuum and lifetimes will be investigated.

  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. Lifetime socioeconomic position and mortality: prospective observational study.

    PubMed Central

    Smith, G. D.; Hart, C.; Blane, D.; Gillis, C.; Hawthorne, V.

    1997-01-01

    OBJECTIVES: To assess the influence of socioeconomic position over a lifetime on risk factors for cardiovascular disease, on morbidity, and on mortality from various causes. DESIGN: Prospective observational study with 21 years of follow up. Social class was determined as manual or non-manual at three stages of participants' lives: from the social class of their father's job, the social class of their first job, and the social class of their job at the time of screening. A cumulative social class indicator was constructed, ranging from non-manual social class at all three stages of life to manual social class at all three stages. SETTING: 27 workplaces in the west of Scotland. PARTICIPANTS: 5766 men aged 35-64 at the time of examination. MAIN OUTCOME MEASURES: Prevalence and level of risk factors for cardiovascular disease; morbidity; and mortality from broad causes of death. RESULTS: From non-manual social class locations at all three life stages to manual at all stages there were strong positive trends for blood pressure, body mass index, current cigarette smoking, angina, and bronchitis. Inverse trends were seen for height, cholesterol concentration, lung function, and being an ex-smoker. 1580 men died during follow up. Age adjusted relative death rates in comparison with the men of non-manual social class locations at all three stages of life were 1.29 (95% confidence interval 1.08 to 1.56) in men of two non-manual and one manual social class; 1.45 (1.21 to 1.73) in men of two manual and one non-manual social class; and 1.71 (1.46 to 2.01) in men of manual social class at all three stages. Mortality from cardiovascular disease showed a similar graded association with cumulative social class. Mortality from cancer was mainly raised among men of manual social class at all three stages. Adjustment for a wide range of risk factors caused little attenuation in the association of cumulative social class with mortality from all causes and from cardiovascular disease

  12. 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.

  13. Calculation of collective effects and beam lifetimes for the LBL (Lawrence Berkeley Laboratory) 1-2 GeV synchrotron radiation source

    SciTech Connect

    Chattopadhyay, S.; Zisman, M.S.

    1987-03-01

    In designing a third-generation high brightness synchrotron radiation source, attention must be paid to the various collective effects that can influence beam performance. We report on calculations, performed with the code ZAP, of the bunch length, the transverse emittance and the beam lifetime (from both Touschek and gas scattering) for our 1-2 GeV storage ring. In addition, we estimate the growth times for both longitudinal and transverse coupled bunch instabilities. Bunch lengths of about 20 ps should be obtainable and intrabeam scattering emittance growth is small. For a limiting undulator gap of 1 cm and residual gas pressure of 1n Torr, the beam lifetime is about 5 hours in the single-bunch mode; in the multibunch mode, lifetimes in excess of 6 hours are expected. These results indicate that all performance goals for the facility should be achievable.

  14. LHC beam-beam compensation studies at RHIC

    SciTech Connect

    Fischer,W.; Abreu, N.; Calaga, R.; Robert-Demolaize, G.; Luo, Y.; Montag, C.

    2009-05-04

    Long-range and head-on beam-beam effects are expected to limit the LHC performance with design parameters. 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 the LHC and RHIC. We present the experimental long-range beam-beam program and report on head-on compensations studies at RHIC, which are based on simulations.

  15. 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.

  16. Charge Lifetime Study of K2CsSb Photocathode Inside a JLAB DC High Voltage Gun

    SciTech Connect

    Mammei, R.; Rao, T.; Suleiman, R.; Poelker, M.; Smedley, J.; McCarter, J.L.

    2011-10-01

    Two photocathodes are frequently considered for generating high average current electron beams and/or beams with high brightness for current and future accelerator applications: GaAs:Cs and K2CsSb. Each photocathode has advantages and disadvantages, and need to demonstrate performance at 'production' accelerator facilities. To this end a K2CsSb photocathode was manufactured at Brookhaven National Lab and delivered to Jefferson Lab within a compact vacuum apparatus at pressure {approx} 5 x 10{sup -11} Torr. This photocathode was installed inside a dc high voltage photogun biased at voltages up to 200 kV, and illuminated with laser light at 440 or 532 nm, to generate beams up to 20 mA. Photocathode charge lifetime measurements indicate that under some conditions this cathode has exceptionally high charge lifetime, without measurable QE decay, even from the center of the photocathode where operation using GaAs photocathodes is precluded due to ion bombardment. These studies also suggest a complex QE decay mechanism likely related to chemistry and localized heating via the laser beam.

  17. 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

  18. 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.

  19. 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.

  20. 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

  1. Barium depletion study on impregnated cathodes and lifetime prediction

    NASA Astrophysics Data System (ADS)

    Roquais, J. M.; Poret, F.; le Doze, R.; Ricaud, J. L.; Monterrin, A.; Steinbrunn, A.

    2003-06-01

    In the thermionic cathodes used in cathode ray-tubes (CRTs), barium is the key element for the electronic emission. In the case of the dispenser cathodes made of a porous tungsten pellet impregnated with Ba, Ca aluminates, the evaporation of Ba determines the cathode lifetime with respect to emission performance in the CRT. The Ba evaporation results in progressive depletion of the impregnating material inside the pellet. In the present work, the Ba depletion with time has been extensively characterized over a large range of cathode temperature. Calculations using the depletion data allowed modeling of the depletion as a function of key parameters. The link between measured depletion and emission in tubes has been established, from which an end-of-life criterion was deduced. Taking modeling into account, predicting accelerated life-tests were performed using high-density maximum emission current (MIK).

  2. Positron annihilation lifetime study of interfaces in ternary polymer blends

    NASA Astrophysics Data System (ADS)

    Meghala, D.; Ramya, P.; Pasang, T.; Raj, J. M.; Ranganathaiah, C.; Williams, J. F.

    2013-06-01

    A new method based on positron lifetime spectroscopy is developed to characterize individual interfaces in ternary polymer blends and hence determine the composition dependent miscibility level. The method owes its origin to the Kirkwood-Risemann-Zimm (KRZ) model for the evaluation of the hydrodynamic interaction parameters (αij) which was used successfully for a binary blend with a single interface. The model was revised for the present work for ternary polymer blends to account for three interfaces. The efficacy of this method is shown for two ternary blends namely poly(styrene-co-acrylonitrile)/poly (ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and polycaprolactone /poly(styrene-co-acrylonitrile)/poly(vinyl chloride) (PCL/SAN/PVC) at different compositions. An effective hydrodynamic interaction parameter, αeff, was introduced to predict the overall miscibility of ternary blends.

  3. Lifetime measurement of the Ar XIV 1s{sup 2}2s{sup 2}2p {sup 2}P{sub 3/2}{sup o} metastable level at the Heidelberg electron-beam ion trap

    SciTech Connect

    Lapierre, A.; Crespo Lopez-Urrutia, J. R.; Braun, J.; Brenner, G.; Bruhns, H.; Fischer, D.; Gonzalez Martinez, A. J.; Mironov, V.; Osborne, C.; Sikler, G.; Soria Orts, R.; Tawara, H.; Ullrich, J.; Shabaev, V. M.; Tupitsyn, I. I.; Volotka, A.

    2006-05-15

    We present the details of an accurate lifetime measurement of the 1s{sup 2}2s{sup 2}2p {sup 2}P{sub 3/2}{sup o} metastable level in boronlike Ar XIV performed at the Heidelberg electron beam ion trap [A. Lapierre et al., Phys. Rev. Lett. 95, 183001 (2005)]. The lifetime was inferred from decay curves resulting from deexcitation of the metastable level to its {sup 2}P{sub 1/2}{sup o} ground state through a magnetic-dipole (M1) transition upon cyclically turning on and off the electron beam. The measured lifetime of 9.573(4)((+12/-5)) ms (stat)(syst) is in disagreement with a trend of theoretical predictions of 9.53(1) ms, which include the effect of the electron anomalous magnetic moment. Systematic effects were investigated by studying with high statistical significance the dependence of the decay times of the curves on various trapping conditions. The asymptotic trend of the decay times observed for increasingly high trapping potentials, which indicates negligible ion losses within a ms time scale, is in agreement with a theoretical model describing the ion escape rate in electrostatic ion traps. However, for high trapping potentials, we observed an unexpected slowly decaying component suggesting the presence of trapped low-energy electrons. Their origin, dynamics, and temperature, as well as their possible effects on the measured lifetime were investigated.

  4. Two-photon excited fluorescence lifetime imaging microscopy for FRET study on protein interactions

    NASA Astrophysics Data System (ADS)

    Qu, Junle; Lin, Ziyang; Liu, Lixin; Guo, Xuan; Chen, Danni; Niu, Hanben

    2005-01-01

    Two-photon excited fluorescence lifetime imaging (2P-FLIM) provides a more direct and precise approach to fluorescence resonance energy transfer (FRET), which allows studying the dynamic behavior of protein-protein interactions in living cells. In this paper, we describe the combination of a Leica TCS SP2 laser scanning microscope and a time-correlated single photon counting (TCSPC) lifetime imaging module developed by Becker & Hickl for two-photon excited fluorescence lifetime imaging. This 2P-FLIM system was used for FRET study on the interaction of heat shock protein hsp27 with p38 MAP kinase in the single living cell. Results show that the reduction in donor (CFP) lifetime in the presence of acceptor (YFP) reveals interactions between the two proteins.

  5. Limitations of lifetime alcohol use disorder assessments: A criterion-validation study.

    PubMed

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

    2016-08-01

    The goal of the present study was to compare etiologically and clinically relevant correlates of lifetime AUD (e.g., alcohol consumption, personality traits, psychiatric disorders) based on a single assessment compared to a cumulative, prospective assessment of lifetime AUD. Data were drawn from the Alcohol, Health and Behavior (AHB; baseline N=489) study, which consisted of a prospective cohort of college students assessed seven times over a 16-year period ([M(SD) age at baseline=18.56 (.97)] and [M(SD) age at final assessment=34.33 (.82)]). The participants were assessed using the Diagnostic Interview Schedule (DIS) for DSM-III at Waves 1-7 and for DSM-IV at Waves 6-7. A single assessment and cumulative assessments of DSM-III lifetime AUD at Wave 6 (M[SD] age=28.98 [1.03]) were used to predict past-year alcohol related variables (e.g., alcohol consumption, drinking motives, drinking expectancies), personality variables, general functioning, lifetime substance use, and lifetime psychiatric disorders at Wave 7. Significantly larger correlations were found between the cumulative assessment and eight of the 25 etiologically relevant correlates of AUD compared to the single assessment. Further, significant incremental validity of cumulative assessment over single, retrospective assessment was observed for 16 of the 25 covariates. Overall, this study provides further support for the value of using prospective data with multiple assessments when determining lifetime history of disorder. PMID:27082748

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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. PMID:22784642

  11. 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

  12. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-04-01

    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*{sub 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.

  13. Beam Loading Studies at CEBAF

    SciTech Connect

    G.A. Krafft; S.N. Simrock; K.L. Mahoney

    1990-09-10

    When the CEBAF accelerator operates at 200 {mu}A beam current, the superconducting cavities run with high beam loading. The CEBAF RF system (including the cavities, klystrons, and control systems) has been measured to obtain the response to low frequency current fluctuations and to obtain the transient response to rapid changes in the beam current. The data were collected both through RF tests where beam pulses are simulated by RF pulses and through beam tests. Both closed loop and open loop measurements were made, and the results are compared to detailed SPICE numerical simulations. It is concluded that CEBAF will operate with high control under a wide variety of loads.

  14. Lifetime carcinogenicity study of 1- and 2-naphthylamine in dogs.

    PubMed Central

    Purchase, I. F.; Kalinowski, A. E.; Ishmael, J.; Wilson, J.; Gore, C. W.; Chart, I. S.

    1981-01-01

    Groups of male and female beagle dogs were given daily doses of 400 mg of various mixtures of naphthylamines for up to 109 months. Survivors were killed at 128 months. A variety of pathological conditions was diagnosed, but the only effect related to treatment was the induction of bladder neoplasms. All dogs which received pure 2-naphthylamine developed transitional-cell carcinomas of the bladder within 34 months. Two of 8 dogs receiving 6% 2-naphthylamine in 1-naphthylamine developed early carcinoma and 2/8 dogs receiving 0.5% 2-naphthylamine in 1-naphthylamine developed haemangioma of the bladder. Some of the dogs receiving 1-naphthylamine (total dose 950 g) and the controls had focal cystitis or hyperplasia, but no neoplasia of the bladder. These results confirm the carcinogenicity of 2-naphthylamine to dogs. No carcinogenic effect of 1-naphthylamine was observed, indicating that it is at least 200 times less potent as a carcinogen than 2-naphthylamine. The incidence of bladder cancer in dogs fed mixtures of both naphthylamines explains why previous experimental and epidemiological studies of impure 1-naphthylamine have revealed carcinogenicity. Images Fig. 1 Fig. 2 PMID:7326199

  15. Development of a simplified gravitational model for lifetime studies of lunar satellite orbits

    NASA Technical Reports Server (NTRS)

    Meyer, Kurt W.

    1992-01-01

    Future lunar missions will involve long stay times in orbit about the moon. The moon's nonspherical gravitational field is the primary perturbation on a low altitude parking orbit. The objective of this study is to determine the orbital lifetime of a nearly circular low altitude parking orbit. In the present analysis, a simplified gravitational model of the moon is introduced which will enable mission designers to easily predict long term changes in lunar parking orbits at the preliminary design level. The development of a simplified gravitational model with sufficient accuracy is necessary to investigate orbital lifetimes for the large number of orbital parameters possible. Utilization of a simplified model will significantly reduce the required computational time needed to perform this analysis. By investigating the effects of the lunar gravity model on the various parking orbits, the parameters which are important in determining lifetime predictions are identified.

  16. 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.

  17. 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.

  18. 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.

  19. 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…

  20. Lifetime of the 1s2s {sup 3}S{sub 1} metastable level in He-like S{sup 14+} measured with an electron beam ion trap

    SciTech Connect

    Crespo Lopez-Urrutia, J. R.; Beiersdorfer, P.; Widmann, K.

    2006-07-15

    A precision measurement of the lifetime of the lowest excited 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.

  1. Hall effect and photoconductivity lifetime studies of gallium nitride, indium nitride, and mercury cadmium telluride

    NASA Astrophysics Data System (ADS)

    Swartz, Craig H.

    A deep understanding of both carrier recombination and transport is necessary for semiconductor engineering, particularly in defining the ultimate limits of performance for a given device before spending the resources to perfect its fabrication. Hall effect measurements utilizing a variable magnetic field are necessary to discriminate between conduction in epitaxial layers and conduction originating at the surface or at an interfacial layer. For thick hydride vapor phase epitaxy (HVPE) grown GaN, variable field Hall measurements revealed the presence of small but significant lower mobility surface and interface electrons which would otherwise lead to errors in interpreting the electrical properties. In addition, QMSA analysis of the measurements indicates that thick GaN samples contain a large spread in electron mobility values, most likely with depth. For molecular beam epitaxial InN, it was found that electrical measurements are affected by surface charge conduction, as well as the non-uniformity of mobility and carrier concentration with depth. Both of these effects mask the surprisingly high quality of the material close to the surface. Photoconductance lifetime and variable-magnetic-field Hall and transient measurements were performed on a series of undoped, In-doped and As-doped HgCdTe grown by MBE and MOCVD. N-type layers often significantly influence the interpretation of the electrical measurements. Even the best Low Wavelength Infrared (LWIR) n-type material still appears to be dominated by defect-related recombination, as intrinsic lifetimes calculated with full band structure can be well above those measured. Mid-Wavelength Infrared (MWIR) lifetimes increase somewhat with carrier concentration, as if the n-type doping process were passivating Schockley-Read-Hall (SRH) defects. P-type MWIR films lie mainly below the predicted values, and their relationship between concentration and lifetime is essentially unchanged by growth technique, indicating that a

  2. 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.

  3. Funneling: An intial beam-dynamics study

    SciTech Connect

    Guy, F.W.; Wangler, T.P.

    1986-04-25

    Funneling two H/sup -/ beams into a single beam of twice the current has been examined as a means of doubling beam current without significantly increasing transverse emittance. Using the PARMILA particle-following code, two 100-mA RFQ output beams at 2 MeV were injected into idealized transport lines for merging two beams into one. Two approaches were studied: (1) the ''minimum-element'' method, in which a minimum number of discrete elements such as quadrupole triplets, buncher cavities, and bending magnets were used to transport and deflect the beam; and (2) the ''quasi-adiabatic'' method, in which a periodic lattice similar to the RFQ provided focusing and minimized abrupt changes in the beam environment. The minimum-element method resulted in an emittance growth ratio epsilon/sub 0//epsilon/sub i/ = 2.5, whereas the quasi-adiabatic emittance growth ratio was about 1.1 (albeit with an idealized line configuration).

  4. 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.

  5. 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.

  6. 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. PMID:20099927

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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…

  12. 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

  13. 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.

  14. Fluorescence Lifetime Correlation Spectroscopic Study of Fluorophore-Labeled Silver Nanoparticles

    PubMed Central

    Ray, Krishanu; Zhang, Jian; Lakowicz, Joseph R.

    2013-01-01

    In this paper, we introduce the use of fluorescence lifetime correlation spectroscopy (FLCS) to study the metal-fluorophore interactions in solution at single fluorophore level. A single-stranded oligonucleotide was chemically bound to a 50 nm diameter single silver particle and a Cy5-labeled complementary single-stranded oligonucleotide was hybridized with the silver particle-bound oligonucleotide. The distance between the fluorophore and silver particle was maintained by a rigid hybridized DNA duplex of 8 nm in length. The single Cy5-DNA-Ag-particles showed more than 10-fold increase in fluorescence intensity, 5-fold decrease in emission lifetimes as compared with Cy5-DNA free molecules in the absence of metal. The decrease of lifetime for the Cy5-DNA-Ag-particle allowed us to resolve the correlation functions of the two species based on the intensity decays. The increased brightness of Cy5-DNA-Ag-particle as compared to free Cy5-DNA resulted in an increased contribution of Cy5-DNA-Ag to the correlation function of the mixture. These results show that the effects of metal particles on fluorophores can be used to detect the small fractional populations of the metal-bound species in the presence of a larger number of less bright species. Our results also suggest that these bright fluorophores conjugated to silver particles could be used as the fluorescent probes for clinical detection in the biological samples with the high background. PMID:18771274

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Funneling: an initial beam dynamics study

    SciTech Connect

    Guy, F.W.; Wangler, T.P.

    1985-04-20

    Funneling two H/sup -/ beams into a single beam of twice the current has been examined as a means of doubling beam current without significantly increasing transverse emittance. Using the PARMILA particle-following code, two 100-mA RFQ output beams at 2 MeV were injected into idealized transport lines for merging two beams into one. Two approaches were studied: (1) the minimum-element method, in which a minimum number of discrete elements such as quadrupole triplets, buncher cavities, and bending magnets were used to transport and deflect the beam; and (2) the quasi-adiabatic method, in which a periodic lattice similar to the RFQ provided focusing and minimized abrupt changes in the beam environment. The minimum-element method resulted in an emittance growth ratio epsilon/sub 0//epsilon/sub i/ = 2.5, whereas the quasi-adiabatic emittance growth ratio was about 1.1 (albeit with an idealized line configuration). 5 refs., 4 figs., 3 tabs.

  20. 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

  1. Plasma traps for beam dynamics studies

    NASA Astrophysics Data System (ADS)

    Okamoto, Hiromi

    2004-05-01

    The collective motion of a space-charge-dominated beam in an accelerator has been investigated by many researchers for many years mainly through numerical simulations and analytic calculations. The recent interest in applying high-power ion beams to diverse purposes has made the understandings of various "space-charge effects" more and more important than ever. It is, however, extremely difficult to carry out the self-consistent theoretical study of such a multi-particle system exposed to complex external driving fields. In fact, we have always been forced to introduce some assumptions or simplifying models to draw approximate conclusions. Efforts have also been devoted to the experimental study of intense beams, but we encounter many practical difficulties again. As we can easily imagine, it is a tough job to observe and measure a particle beam traveling at great speed. Further, in a real accelerator, key experimental parameters, such as beam density, betatron tunes, magnet arrangements, etc., are not well controllable over a wide range. In order to overcome all these difficulties in conventional approaches, we proposed a novel experimental method utilizing a compact plasma trap system (instead of a huge, very expensive accelerator system) [1]. The basic idea is quite simple; namely, a charged-particle beam in an accelerator, if seen from the rest frame, is physically almost equivalent to a single-species plasma in a trap system. It is thus possible to employ a plasma trap for the systematic experimental study of space-charge-dominated beams. In this talk, a typical trap design is given and its applications to some beam-dynamics problems are discussed. [1] H. Okamoto and H. Tanaka, Nucl. Instr. Meth. A 437 (1999) 178; H. Okamoto, Y. Wada and R. Takai, Nucl. Instr. Meth. A 485 (2002) 244.

  2. ORNL Radioactive Beams for Stellar Explosion Studies

    NASA Astrophysics Data System (ADS)

    Smith, Michael S.

    2008-05-01

    Thermonuclear reactions on unstable nuclei generate the energy that power nova explosions and X-ray bursts. In these explosions and others such as supernovae, these reactions serve to synthesize nuclei that (via their decay) can serve as tracers of the explosion mechanism. A powerful approach to improve our understanding of these explosions is to utilize beams of radioactive nuclei for direct and indirect measurements of these reactions. We are pursuing this approach at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL) to study reactions in the rp-process (with beams of 17,18F) and the r-process (with beams of 82Ge, 84Se 130,132Sn, 134Te). These measurements are combined with synergistic data evaluations and element synthesis calculations. Highlights of recent results are presented.

  3. Studies of Beam Dynamics in Cooler Rings

    SciTech Connect

    Dietrich, J.; Stein, J.; Meshkov, I.; Sidorin, A.; Smirnov, A.

    2006-03-20

    This report describes the numerical simulation of the crystalline proton beam formation in COSY using BETACOOL code. The study includes the description of experimental results at NAP-M storage ring where the large reduction of the momentum spread was observed for first time. The present simulation shows that this behavior of proton beam can not be explained as ordered state of protons. The numerical simulation of crystalline proton beams was done for COSY parameters. The number of protons when the ordering state can be observed is limited by value 106 particles and momentum spread less then 10-6. Experimental results for the attempt to achieve of ordered state of proton beam for COSY is presented. This work is supported by RFBR grant no. 05-02-16320 and INTAS grant no. 03-54-5584.

  4. On the potential of positron lifetime spectroscopy for the study of early stages of zeolites formation from their amorphous precursors

    NASA Astrophysics Data System (ADS)

    Bosnar, S.; Kosanović, C.; Subotić, B.; Bosnar, D.; Kajcsos, Zs.; Liszkay, L.; Lohonyai, L.; Molnár, B.; Lázár, K.

    2007-02-01

    The applicability of positron lifetime (LT) spectroscopy to the study of progress of formation of Secondary Building Units (SBU) in gels yielding in FAU and LTA type zeolites was investigated. Samples were prepared from aluminosilicate gels with various degrees of local structural order. LT measurements were performed at room temperature in air and in vacuum. Coexistence of annihilation modi with long lifetime components was shown; a correlation with precursors of nucleation and type of exchanged ions was also indicated.

  5. Beam-beam effects in the Tevatron

    SciTech Connect

    Shiltsev, V.; Alexahin, Y.; Lebedev, V.; Lebrun, P.; Moore, R.S.; Sen, T.; Tollestrup, A.; Valishev, A.; Zhang, X.L.; /Fermilab

    2005-01-01

    The Tevatron in Collider Run II (2001-present) is operating with 6 times more bunches, many times higher beam intensities and luminosities than in Run I (1992-1995). Electromagnetic long-range and head-on interactions of high intensity proton and antiproton beams have been significant sources of beam loss and lifetime limitations. 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 operations, predict the performance for planned luminosity upgrades, and discuss ways to improve it.

  6. 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

  7. 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.

  8. 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)

  9. Experimental study of proton beam halo in mismatched beams

    SciTech Connect

    Allen, C. K.; Chan, K. D.; Colestock, P. L. ,; Garnett, R. W.; Gilpatrick, J. D.; Qiang, J.; Lysenko, W. P.; Smith, H. V.; Schneider, J. D.; Sheffield, R. L.; Wangler, Thomas P.,; Schulze, M. E.; Crandall, K. R.

    2002-01-01

    We report measurements of transverse beam-halo formation in mismatched proton beams in a 52-quadrupole FODO-transport channel following the 6.7 MeV RFQ at the Low-Energy Demonstration Accelerator (LEDA) at Los Alamos. Beam profiles in both transverse planes were measured using a new diagnostic device that consists of a movable carbon filament for measurement of the beam core, and scraper plates for measurement of the outer part of the distributions. The initial results indicate a surprisingly strong growth rate of the rms emittance even for the modest space-charge tune depressions of the experiment. Our results are consistent with the complete transfer of free energy of the mismatched beams into emittance growth within 10 envelope oscillations for both the breathing and the quadrupole modes.

  10. Beam-beam effects in the Tevatron Run II

    SciTech Connect

    Shiltsev, V.; Alexahin, Yu.; Lebedev, V.; Lebrun, P.; Moore, R.; Sen, T.; Valishev, A.; Zhang, X.L.; /FERMILAB

    2005-05-01

    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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. Defects in electron-irradiated GaAs studied by positron lifetime spectroscopy

    SciTech Connect

    Polity, A.; Rudolf, F.; Nagel, C.; Eichler, S.; Krause-Rehberg, R.

    1997-04-01

    A systematic study of electron-irradiation-induced defects in GaAs was carried out. The irradiation was performed at low temperature (4 K) with an incident energy of 2 MeV. Both, the defect formation and annealing behavior were studied in dependence on the fluence (10{sup 15}--10{sup 19} cm{sup {minus}2}) in undoped, n-, and p-doped GaAs. Temperature-dependent positron lifetime measurements were performed between 20 and 600 K. The thermal stability of defects was studied by annealing experiments in the temperature range of 90--600 K. A defect complex, which anneals in a main stage at 300 K, was found in all GaAs samples after electron irradiation. A possible candidate for this defect is a complex of a vacancy connected with an intrinsic defect. A second vancancylike defect was observed in n-type material after annealing at 550 K. This defect was assumed to be in the As sublattice. {copyright} {ital 1997} {ital The American Physical Society}

  20. Personalized Prediction of Lifetime Benefits with Statin Therapy for Asymptomatic Individuals: A Modeling Study

    PubMed Central

    Ferket, Bart S.; van Kempen, Bob J. H.; Heeringa, Jan; Spronk, Sandra; Fleischmann, Kirsten E.; Nijhuis, Rogier L. G.; Hofman, Albert; Steyerberg, Ewout W.; Hunink, M. G. Myriam

    2012-01-01

    Background Physicians need to inform asymptomatic individuals about personalized outcomes of statin therapy for primary prevention of cardiovascular disease (CVD). However, current prediction models focus on short-term outcomes and ignore the competing risk of death due to other causes. We aimed to predict the potential lifetime benefits with statin therapy, taking into account competing risks. Methods and Findings A microsimulation model based on 5-y follow-up data from the Rotterdam Study, a population-based cohort of individuals aged 55 y and older living in the Ommoord district of Rotterdam, the Netherlands, was used to estimate lifetime outcomes with and without statin therapy. The model was validated in-sample using 10-y follow-up data. We used baseline variables and model output to construct (1) a web-based calculator for gains in total and CVD-free life expectancy and (2) color charts for comparing these gains to the Systematic Coronary Risk Evaluation (SCORE) charts. In 2,428 participants (mean age 67.7 y, 35.5% men), statin therapy increased total life expectancy by 0.3 y (SD 0.2) and CVD-free life expectancy by 0.7 y (SD 0.4). Age, sex, smoking, blood pressure, hypertension, lipids, diabetes, glucose, body mass index, waist-to-hip ratio, and creatinine were included in the calculator. Gains in total and CVD-free life expectancy increased with blood pressure, unfavorable lipid levels, and body mass index after multivariable adjustment. Gains decreased considerably with advancing age, while SCORE 10-y CVD mortality risk increased with age. Twenty-five percent of participants with a low SCORE risk achieved equal or larger gains in CVD-free life expectancy than the median gain in participants with a high SCORE risk. Conclusions We developed tools to predict personalized increases in total and CVD-free life expectancy with statin therapy. The predicted gains we found are small. If the underlying model is validated in an independent cohort, the tools may be

  1. Ka-Band Beam Steering Reflectarray Study

    NASA Technical Reports Server (NTRS)

    McSpadden, James O.; Fan, Lu; Chang, Kai; Huang, John

    1999-01-01

    A one-meter diameter, 32 GHz active microstrip reflectarray capable of electronic beam steering has been studied. The 15_500 element array consists of rnicrostrip patch antennas, microstrip phase shifters, and dc bias lines. Specifically, the study focused on the solid-state devices and dc bias layouts for scanning the beam linearly 45 from boresight using 2-bit phase shifters. Three configurations are recommended for the reflectarray with integrated 2-bit phase shifters where the total substrate and cladding mass varies from 8 kg to 14 kg. Additionally, dc power requirements for p-i-n diodes in 1-bit, 2-bit and 3-bit phase shifting circuits are approximately 19 W, 19 W, and 39 W, respectively. The dc power requirement for phase shifters using passive MESFETs is much less than 1 W.

  2. Radiative Lifetimes of V I and V II

    NASA Astrophysics Data System (ADS)

    Den Hartog, E. A.; Lawler, J. E.; Wood, M. P.

    2014-11-01

    New radiative lifetimes are reported for 168 levels of V I ranging in energy from 18086 cm-1 to 47702 cm-1, and for 31 levels of V II ranging in energy from 34593 cm-1 to 47420 cm-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.

  3. 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.

  4. Fluorescence lifetime imaging and intravascular ultrasound: co-registration study using ex vivo human coronaries.

    PubMed

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

    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

  5. 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

  6. [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

  7. Study on the lifetime of EPDM seals in nuclear-powered vessels

    NASA Astrophysics Data System (ADS)

    Le Lay, F.

    2013-03-01

    DCNS provides the French Navy with ships and services, including through-life support (TLS). For that activity, the lifetime of seals has to be studied, either because periods between maintenance stops are longer, or because some seals cannot be replaced in short time and without removing big equipments. Among different kinds of seals we studied, we focus on EPDM seals. First of all, we studied their thermal ageing in service, through accelerated ageing procedures and Arrhenius law. Their mechanical properties after 19 and 32 years were estimated. They showed a reasonable evolution. Then, the effects of gamma-radiations were studied at different doses: 10, 20 and 400 kGy combining temperature and radiation and 18, 33 and 250 kGy (only radiation). In both cases, seals were irradiated after thermal ageing. Mechanical properties (compression, tensile, and hardness) were measured at the surface and in the middle of the seals (10×10 mm2 section and 68 mm diameter). In addition, physicochemical tests were performed (TGA and DSC). The results showed that in normal conditions, the properties of the EPDM seals vary a little till 32 years in service (<20% in compression, and <30% in elongation at break in tension). On the other hand, with doses of 250 and 400 kGy, the evolution of the seals is important (+130% compression force). These results are in good concordance with other studies on this kind of polymer, where the dose at which there is a significant modification is about 250 kGy (Madani, 2004; Zaharescu and Podina, 2001).

  8. 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…

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. Beam structure and transverse emittance studies of high-energy ion beams

    NASA Astrophysics Data System (ADS)

    Saadatmand, K.; Johnson, K. F.; Schneider, J. D.

    1991-05-01

    A visual diagnostic technique was developed to monitor and study ion beam structure shape and size along a transport line. In this technique, a commercially available fluorescent screen is utilized in conjunction with a video camera. This visual representation of the beam structure is digitized and enhanced through use of false color coding and displayed on a TV monitor for on-line viewing. Digitized information is stored for further off-line processing (e.g., extraction of beam profiles). An optional wire grid placed upstream of the fluor screen adds the capability of transverse emittance (or angular spread) measurement to this technique. This diagnostic allows real time observation of the beam response to parameter changes (e.g., evolution of the beam structure, shifts in the beam intensity at various spatial locations within the beam perimeter, and shifts in the beam center and position).

  15. Luminosity Lifetime

    SciTech Connect

    Zisman, M.S.

    1997-04-01

    In a symmetric or 'energy transparent' relativistic collider, the luminosity is given by L = N{sup 2}f{sub c}/4{pi}{sigma}*{sub x}{sigma}*{sub y} where N is the number of electrons or positrons per bunch, {sigma}*{sub x} ({sigma}*{sub y}) is the horizontal (vertical) rms beam size at the interaction point (IP), and f{sub c} is the collision frequency. If the beam sizes remain constant as the luminosity decreases, then the time dependence of luminosity is contained entirely in the time dependence of the beam currents, i.e., N O N(t), and we can rewrite the equation as L(t) = N{sup 2}(t)f{sub c}/4{pi}{sigma}*{sub x}{sigma}*{sub y}. There are two distinct categories for luminosity loss. In the first category are loss processes due to collisions between the two beams, that is, processes associated directly with the luminosity. In the second category (see below) are single-beam loss processes. The processes in the first category relevant to a high-energy collider are Bhabha scattering (e{sup +}e{sup -} O e{sup +}e{sup -}) and 'radiative' Bhabha scattering (e{sup +}e{sup -} O e{sup +}e{sup -}{gamma}). In the first process, a beam particle is lost if its angular deflection is beyond the ring's transverse acceptance; in the second process, loss occurs if the beam particle's momentum change is outside the longitudinal acceptance of the ring (typically determined by the RF bucket height).

  16. 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

  17. Characterization of radiation-induced lattice vacancies in intermetallic compounds by means of positron-lifetime studies

    NASA Astrophysics Data System (ADS)

    Würschum, R.; Badura-Gergen, K.; Kümmerle, E. A.; Grupp, C.; Schaefer, H.-E.

    1996-07-01

    In the present paper a characterization of atomic vacancies in intermetallic compounds is given by means of positron-lifetime measurements after electron irradiation and comparison with the states after preparation, after long-time annealing, or in high-temperature equilibrium. In TiAl, Ti3Al, and Ni3Al no structural vacancies (detection limit CV=10-6) are observed at ambient temperature. This confirms that in these compounds slight deviations from stoichiometry are compensated by antisite atoms. In the Al-poor B2 alloys FeAl and NiAl, on the other hand, remnant vacancies exist due to the high thermal equilibrium vacancy concentrations and their slow diffusivities. The kinetics of vacancy elimination in FeAl and NiAl is discussed. A substantial temperature dependence of the positron lifetime in vacancies is detected in close-packed intermetallics which is attributed to an increased atomic relaxation or partial positron detrapping at high temperatures. In contrast to that, the temperature dependence of the positron lifetime in vacancies is small in the open-structured B2 aluminides. The lifetimes τf of free delocalized positrons in transition-metal aluminides and in NiZr and NiTi can be correlated to those of the pure components, taking into account the densities of valence electrons. For the positron lifetimes τ1 of vacancies in intermetallic compounds, values of τ1/τf=1.5-1.7 are observed similar as in the pure metals. Annealing studies of B2-FeAl after electron irradiation yield time constants for the disappearance of vacancies identical to those deduced recently for the equilibration of thermal vacancies. In electron-irradiated Ti aluminides annealing processes at 250 K and 450 K are observed where the latter process is tentatively attributed to long-range migration of vacancies.

  18. Lipophilic porphyrin microparticles induced by AOT reverse micelles: a fluorescence lifetime imaging study.

    PubMed

    Togashi, Denisio M; Costa, Sílvia M B; Sobral, Abílio J F N

    2006-01-20

    Fluorescence Lifetime Imaging Microscopy (FLIM) technique was applied to investigate the fluorescence dynamics and structural features of large colloidal aggregates of meso-tetra(N-dodecyl-4-amino sulfonyl-phenyl)porphyrin (PC12) induced by Sodium 1,4-bis(2-ethyl hexyl)sulfosuccinate (AOT) reverse micelles. The aggregate's particle sizes (down to 1 microm) obtained from the confocal fluorescence images matched with the particle sizes measured in the images obtained from Scanning Electron Microscopy (SEM). The fluorescence decays for those aggregates in the micro spatial domain show triexponential fluorescence lifetimes (tau1 approximately 12 ns, tau2 approximately 3 ns and tau3 approximately 1 ns) which are independent of the aggregate's size. PMID:16154681

  19. Measurements of photocathode operational lifetime at beam currents up to 10-mA using an improved DC high voltage GaAs photogun

    SciTech Connect

    J. Grames; M. Poelker; P. Adderley; J. Brittian; J. Clark; J. Hansknecht; D. Machie; M.L. Stutzman; K. Surles-Law

    2007-06-01

    This work extends past research at Jefferson Lab aimed at better appreciating the mechanisms that limit photocathode operational lifetime at high current (> 1 mA). Specifically, the performance of an improved 100 kV DC high voltage load locked photogun will be described. Although difficult to measure directly, we believe the new gun has better vacuum conditions compared to the original gun, as indicated by enhanced photocathode lifetimes exceeding 2000 C using a 1.55 mm diameter drive laser spot at the photocathode. In addition, the dependence of the lifetime on the laser spot size at the photocathode was measured and a charge density lifetime exceeding 10^6 C/cm^2 was measured with a 0.32 mm laser spot diameter.

  20. DSAM Lifetime Studies for Gd-Nd nuclei with EUROBALL and AFRODITE

    SciTech Connect

    Lieder, E. O.; Lieder, R. M.; Pasternak, A. A.; Carlsson, B. G.; Ragnarsson, I.; Bark, R. A.; Gueorguieva, E.; Lawrie, J. J.; Mullins, S. M.; Papka, P.; Kheswa, Y.; Sharpey-Schafer, J. F.; Gast, W.; Duchene, G.

    2008-05-12

    Lifetimes of high-spin states have been measured for {sup 142}Gd and {sup 134}Nd with EU-ROBALL IV and AFRODITE, respectively, using DSAM. From calculations in the cranked Nilsson-Strutinsky model it was concluded that at the high-spin states of the (+,0){sub 1} band, {sup 142}Gd represents a triaxial nucleus rotating around the longest principal axis.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Impact of obesity, overweight and underweight on life expectancy and lifetime medical expenditures: the Ohsaki Cohort Study

    PubMed Central

    Kuriyama, Shinichi; Kakizaki, Masako; Ohmori-Matsuda, Kaori; Sone, Toshimasa; Hozawa, Atsushi; Kawado, Miyuki; Hashimoto, Shuji; Tsuji, Ichiro

    2012-01-01

    Objectives People who are obese have higher demands for medical care than those of the normal weight people. However, in view of their shorter life expectancy, it is unclear whether obese people have higher lifetime medical expenditure. We examined the association between body mass index, life expectancy and lifetime medical expenditure. Design Prospective cohort study using individual data from the Ohsaki Cohort Study. Setting Miyagi Prefecture, northeastern Japan. Participants The 41 965 participants aged 40–79 years. Primary and secondary outcome measures The life expectancy and lifetime medical expenditure aged from 40 years. Results In spite of their shorter life expectancy, obese participants might require higher medical expenditure than normal weight participants. In men aged 40 years, multiadjusted life expectancy for those who were obese participants was 41.4 years (95% CI 38.28 to 44.70), which was 1.7 years non-significantly shorter than that for normal weight participants (p=0.3184). Multiadjusted lifetime medical expenditure for obese participants was £112 858.9 (94 954.1–131 840.9), being 14.7% non-significantly higher than that for normal weight participants (p=0.1141). In women aged 40 years, multiadjusted life expectancy for those who were obese participants was 49.2 years (46.14–52.59), which was 3.1 years non-significantly shorter than for normal weight participants (p=0.0724), and multiadjusted lifetime medical expenditure was £137 765.9 (123 672.9–152 970.2), being 21.6% significantly higher (p=0.0005). Conclusions According to the point estimate, lifetime medical expenditure might appear to be higher for obese participants, despite their short life expectancy. With weight control, more people would enjoy their longevity with lower demands for medical care. PMID:22581797

  6. 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.

  7. Macroparticle simulations of antiproton lifetime at 150 GeV in the te vatron

    SciTech Connect

    Qiang, Ji; Ryne, Robert D.; Sen, Tanaji; Xiao, Meiqin

    2003-05-09

    In this paper we report on a systematic study of antiproton lifetime at the injection energy of 150 GeV in the Tevatron. Our parallel beam-beam model can handle both strong-strong and weak-strong beam-beam collisions with arbitrary beam-beam separation and beam distributions. In this study, we have only used the weak-strong capability due to the fact that the antiproton intensity is much smaller than the proton intensity. We have included all 72 long-range beam-beam collisions with a linear transfer map between adjacent collision points and taken into account linear chromaticity. The effects of antiproton emittance, beam-beam separation, proton intensity, and machine chromaticity have been investigated. Initial results show that the antiproton lifetime as a function of the proton intensity from the simulation is in good agreement with that from the experimental measurements. The antiproton lifetime can be significantly improved by increasing the beam separation and by reducing the antiproton emittance.

  8. Position-resolved Positron Annihilation Lifetime Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wagner, A.; Butterling, M.; Fiedler, F.; Fritz, F.; Kempe, M.; Cowan, T. E.

    2013-06-01

    A new method which allows for position-resolved positron lifetime spectroscopy studies in extended volume samples is presented. In addition to the existing technique of in-situ production of positrons inside large (cm3) bulk samples using high-energy photons up to 16 MeV from bremsstrahlung production, granular position-sensitive photon detectors have been employed. A beam of intense bremsstrahlung is provided by the superconducting electron linear accelerator ELBE (Electron Linear Accelerator with high Brilliance and low Emittance) which delivers electron bunches of less than 10 ps temporal width and an adjustable bunch separation of multiples of 38 ns, average beam currents of 1 mA, and energies up to 40 MeV. Since the generation of bremsstrahlung and the transport to the sample preserves the sharp timing of the electron beam, positrons generated inside the entire sample volume by pair production feature a sharp start time stamp for positron annihilation lifetime studies with high timing resolutions and high signal to background ratios due to the coincident detection of two annihilation photons. Two commercially available detectors from a high-resolution medial positron-emission tomography system are being employed with 169 individual Lu2SiO5:Ce scintillation crystals, each. In first experiments, a positron-lifetime gated image of a planar Si/SiO2 (pieces of 12.5 mm × 25 mm size) sample and a 3-D structured metal in Teflon target could be obtained proving the feasibility of a three dimensional lifetime-gated tomographic system.

  9. 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.

  10. Study on nanosecond pulsed electron beam generation

    NASA Astrophysics Data System (ADS)

    Ponomarev, D.; Kholodnaya, G.; Remnev, G.; Kaikanov, M.; Sazonov, R.

    2014-11-01

    The paper presents the findings of an investigation on volt-ampere characteristics of the diode with explosive emission cathodes of different constructions (blade metal-dielectric (MD-cathode) and solid graphite cathodes) under the change of the anode-cathode gap in wide ranges. The investigations were carried out using the TEA-500 pulsed electron accelerator. The total current of the electron beam was measured using the Faraday cup (FC). A 0.5-mm foiled glass fiber laminate was used as an emitting edge of the cathode in the experimental study with the explosive emission blade MD-cathode. Based on the obtained results, the conclusion was made that the graphite cathode has the most effective efficiency factor.

  11. 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.

  12. 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.

  13. Study of the ionic transport in polymer electrolyte using positron lifetime distribution method

    NASA Astrophysics Data System (ADS)

    Peng, Z. L.; Itoh, Y.; Li, S. Q.; Wang, S. J.

    1996-09-01

    Positron annihilation spectroscopy has been applied to measure the free-volume hole distribution in poly(ether urethane) as a function of temperature. The hole radius distribution determined from orthopositronium lifetime distribution is found to shift to a larger values with increasing temperature. This result, combined with the variation of ionic conductivity, suggests that carrier ions do not migrate naked but are bound to polymer segments through ion-dipole interaction forces, and the ion migration is controlled primarily by segmental motion of the polymer.

  14. 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.

  15. Lifetime Measurements Using the Jefferson Lab Load-Lock Electron Gun

    NASA Astrophysics Data System (ADS)

    Grames, J.; Adderley, P.; Baylac, M.; Brittian, J.; Charles, D.; Clark, J.; Hansknecht, J.; Poelker, M.; Stutzman, M.; Surles-Law, K.

    2005-08-01

    Lifetime measurements of bulk GaAs using a 100 kV load-lock electron gun and beam line were made. Initial tests used anodized samples to study lifetime under various conditions (gun vacuum, laser spot location, activated area). Subsequent tests used a mechanical mask to limit the active area and included improved monitoring of the gun chamber and beam line vacuum pressure. Results of these measurements support claims made at past workshops, namely photocathode lifetime improves when gun vacuum is enhanced and when electron emission from the edge of the photocathode is eliminated. The dependence upon laser spot location is less certain. Tests studying lifetime at higher beam intensity (I ~ 8 mA) have begun.

  16. TEBPP: Theoretical and Experimental study of Beam-Plasma-Physics

    NASA Technical Reports Server (NTRS)

    Anderson, H. R.; Bernstein, W.; Linson, L. M.; Papadopoulos, K.; Kellogg, P. J.; Szuszczewicz, E. P.; Hallinan, T. J.; Leinbach, H.

    1980-01-01

    The interaction of an electron beam (0 to 10 keV, 0 to 1.5 Amp) with the plasma and neutral atmospheres at 200 to 400 km altitude is studied with emphasis on applications to near Earth and cosmical plasmas. The interaction occurs in four space time regions: (1) near electron gun, beam coming into equilibrium with medium; (2) equilibrium propagation in ionosphere; (3) ahead of beam pulse, temporal and spatial precursors; (4) behind a beam pulse. While region 2 is of the greatest interest, it is essential to study Region 1 because it determines the characteristics of the beam as it enters 2 through 4.

  17. 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.

  18. 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

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

    NASA Astrophysics Data System (ADS)

    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.

  20. 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

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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.

  4. Experimental and theoretical study of the nf-level lifetimes of potassium

    SciTech Connect

    Glodz, M.; Huzandrov, A.; Sydoryk, I.; Szonert, J.; Safronova, M. S.; Klavins, J.

    2008-02-15

    The theoretical and experimental values of the 5f, 6f, 7f, and 8f radiative lifetimes {tau} of neutral potassium are reported. The reduced matrix elements for all allowed electric-dipole nf{sub 5/2}-n{sup '}d{sub 5/2}, nf{sub 5/2}-n{sup '}d{sub 3/2}, and nf{sub 7/2}-n{sup '}d{sub 5/2} transitions with n=5-8 in K are calculated using the relativistic linearized coupled-cluster method with single and double excitations of Dirac-Fock wave functions included to all orders in many-body perturbation theory. The resulting electric-dipole matrix elements are used to evaluate the lifetimes of the 5f, 6f, 7f, and 8f states in neutral K and their uncertainties. The contributions from the nf{sub 5/2}-n{sup '}g{sub 7/2}, nf{sub 7/2}-n{sup '}g{sub 7/2}, and nf{sub 7/2}-n{sup '}g{sub 9/2} transitions to the lifetimes of the 6f, 7f, and 8f states are evaluated using the third-order many-body perturbation theory and are found to be very small. The theoretical results are {tau}{sub 5f}=117(4) ns, {tau}{sub 6f}=195(4) ns, {tau}{sub 7f}=301(6) ns, and {tau}{sub 8f}=441(9) ns. The experiment is performed in a cell using time-resolved fluorescence spectroscopy. The nf states are excited stepwise, 4s{yields}4p{yields}nf, using two pulsed synchronous dye lasers for the dipole and quadrupole transitions, respectively. The measured values {tau}{sub 5f}=117(3) ns, {tau}{sub 6f}=190(6) ns, {tau}{sub 7f}=309(8) ns, and {tau}{sub 8f}=428(10) ns are in excellent agreement with the present theoretical calculations.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Lifetime Smoking History and Cause-Specific Mortality in a Cohort Study with 43 Years of Follow-Up

    PubMed Central

    Taghizadeh, Niloofar; Vonk, Judith M.; Boezen, H. Marike

    2016-01-01

    Background In general, smoking increases the risk of mortality. However, it is less clear how the relative risk varies by cause of death. The exact impact of changes in smoking habits throughout life on different mortality risks is less studied. Methods We studied the impact of baseline and lifetime smoking habits, and duration of smoking on the risk of all-cause mortality, mortality of cardiovascular diseases (CVD), chronic obstructive pulmonary disease (COPD), any cancer and of the four most common types of cancer (lung, colorectal, prostate, and breast cancer) in a cohort study (Vlagtwedde-Vlaardingen 1965–1990, with a follow-up on mortality status until 2009, n = 8,645). We used Cox regression models adjusted for age, BMI, sex, and place of residence. Since previous studies suggested a potential effect modification of sex, we additionally stratified by sex and tested for interactions. In addition, to determine which cause of death carried the highest risk we performed competing-risk analyses on mortality due to CVD, cancer, COPD and other causes. Results Current smoking (light, moderate, and heavy cigarette smoking) and lifetime persistent smoking were associated with an increased risk of all-cause, CVD, COPD, any cancer, and lung cancer mortality. Higher numbers of pack years at baseline were associated with an increased risk of all-cause, CVD, COPD, any cancer, lung, colorectal, and prostate cancer mortality. Males who were lifetime persistent pipe/cigar smokers had a higher risk of lung cancer [HR (95% CI) = 7.72 (1.72–34.75)] as well as all-cause and any cancer mortality. A longer duration of smoking was associated with a higher risk of COPD, any and lung cancer [HR (95% CI) = 1.06 (1.00–1.12), 1.03 (1.00–1.06) and 1.10 (1.03–1.17) respectively], but not with other mortality causes. The competing risk analyses showed that ex- and current smokers had a higher risk of cancer, CVD, and COPD mortality compared to all other mortality causes. In

  11. 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.

  12. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Yuan T.

    1991-03-01

    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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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%.

  19. Summary update of the Brookhaven tritium toxicity program with emphasis on recent cytogenetic and lifetime-shortening studies

    SciTech Connect

    Carsten, A.L.; Benz, R.D.; Hughes, W.P.; Ichimasa, Yusuke; Ikushima, Takaji; Tezuka, Hideo

    1988-01-01

    A number of years ago a multiparameter program to evaluate the toxicity of tritiated water (HTO) was undertaken in the Medical Department at Brookhaven National Laboratory. The results of most of these studies have been published and will receive brief attention. Emphasis will be placed on the unpublished studies involving the induction of sister chromatid exchanges (SCE's) in bone marrow of mice, new biochemical information, and preliminary results on lifetime-shortening and carcinogenesis. In brief, male Hale-Stoner Brookhaven (HSB) mice maintained on HTO concentrations ranging from 3.0 to 30.0 ..mu..Ci/ml exhibited essentially the same number of SCE's per cell throughout their lifetime. Control mice showed a decrease in number of SCE's with age. The lack of a dose-response effect and the constant level of SCE's in HTO mice as compared to controls will be discussed. In the carcinogenesis study C57BL/6J male mice received various x-ray or HTO regimens. Mortality data from these and other studies in which CBA/Ca/BNL mice received single x-ray exposures or equivalent integrated dose exposures by single HTO injections will be discussed. 25 refs., 4 figs.

  20. Molecular collision studies with Stark-decelerated beams

    NASA Astrophysics Data System (ADS)

    Meijer, Gerard

    2008-03-01

    Molecular scattering behaviour has generally proven difficult to study at low collision energies. We formed a molecular beam of OH radicals with a narrow velocity distribution and a tunable velocity by passing the beam through a Stark decelerator [1]. The transition probabilities for inelastic scattering of the OH radicals with Xe atoms were measured as a function of the collision energy in the range of 50 to 400 wavenumbers. The behaviour of the cross-sections for inelastic scattering near the energetic thresholds was accurately measured, and excellent agreement was obtained with cross-sections derived from coupled- channel calculations on ab initio computed potential energy surfaces [2]. For collision studies at lower energies, the decelerated beams of molecules can be loaded into a variety of traps. In these traps, electric fields are used to keep the molecules confined in a region of space where they can be studied in complete isolation from the (hot) environment. Typically, 10^5 state- selected molecules can be trapped for times up to several seconds at a density of 10^7 mol/cm^3 and at a temperature of several tens of mK [3]. The long interaction time afforded by the trap has been exploited to measure the infrared radiative lifetime of vibrationally excited OH radicals, for instance, as well as to study the far-infrared optical pumping of these polar molecules due to blackbody radiation [4]. As an alternative to these traps, we have demonstrated an electrostatic storage ring for neutral molecules. In its simplest form, a storage ring is a trap in which the molecules - rather than having a minimum potential energy at a single location in space - have a minimum potential energy on a circle. To fully exploit the possibilities offered by a ring structure, it is imperative that the molecules remain in a bunch as they revolve around the ring. This ensures a high density of stored molecules, moreover, this makes it possible to inject multiple - either co-linear or

  1. IRT-Sofia BNCT beam tube optimization study.

    PubMed

    Belousov, S; Mitev, M; Ilieva, K; Riley, K; Harling, O

    2011-12-01

    An optimization study of IRT-Sofia BNCT beam tube is presented. In the study we used the MIT/FCB experience. The enlarging of filter/moderator cross section dimensions and the decreasing of collimator length within the limits of the IRT-Sofia reactor design were analyzed. The influence of beam and reactor core axes non-coincidence on the beam properties was also evaluated. The irradiation resistance of polytetrafluoroethylene (Teflon(®)) was also evaluated. The results provide information for making decisions on the IRT-Sofia BNCT beam construction. PMID:21439839

  2. 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.

  3. 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.

  4. 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. PMID:22191620

  5. 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

  6. 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

  7. ORNL Radioactive Beams for Stellar Explosion Studies

    NASA Astrophysics Data System (ADS)

    Smith, Michael S.

    2010-08-01

    At ORNL, we are using unique radioactive beams to measure scattering, transfer, and capture reactions to help understand exploding stars such as novae, supernovae, and X-ray bursts. Recent results have been obtained with beams of 26Al, 17F, and 130,132Sn, utilizing gas targets, silicon strip detectors, and recoil separators. More exciting work is planned at the future FRIB facility. We are also using synergistic nuclear data evaluations and the Computational Infrastructure for Nuclear Astrophysics to investigate the astrophysical impact of our measurements.

  8. 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.

  9. 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.

  10. Beam Dynamics Studies for the SPARC Project

    SciTech Connect

    Ferrario, M.; Biagini, Maria E.; Boscolo, M.; Fusco, V.; Guiducci, S.; Migliorati, M.; Serafini, L.; Vaccarezza, C.; Bartolini, R.; Giannessi, L.; Quattromini, M.; Ronsivalle, C.; Limborg, C.G.; /Unlisted /Unlisted /ENEA, Frascati /SLAC

    2008-03-17

    The aim of the SPARC project, is to promote an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments. We discuss in this paper the status of the beam dynamics simulation activities.

  11. Beam-tracking studies with RINGBEARER II

    SciTech Connect

    Masamitsu, J.A.; Yu, S.S.; Chambers, F.W.

    1982-11-22

    This report presents results from the RINGBEARER II linearized monopole/dipole particle simulation for an intense relativistic electron beam propagating in a gas near three types of channels: (1) pre-existing conductivity, (2) density, and (3) density with pre-existing conductivity. Comparisons are made with earlier analytic results for the initial conditions for the pre-existing conductivity channel.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. Lifetime prevalence and correlates of suicidal ideation, plan, and single and multiple attempts in a Korean nationwide study.

    PubMed

    Jeon, Hong Jin; Lee, Jun-Young; Lee, Young Moon; Hong, Jin Pyo; Won, Seung-Hee; Cho, Seong-Jin; Kim, Jin-Yeong; Chang, Sung Man; Lee, Dongsoo; Lee, Hae Woo; Cho, Maeng Je

    2010-09-01

    This was the first Korean national study to evaluate prevalence and correlates of suicidal behavior, and to compare multiple and single attempts. A total of 6510 adults completed face-to-face interviews (response rate, 81.7%) through randomly chosen one-person-per-households. Lifetime prevalence and correlates were evaluated with the Korean version of Composite International Diagnostic Interview (K-CIDI), and a questionnaire to inquire about suicidal behaviors. The lifetime prevalence of suicidal ideation, plan, and attempt in South Korea was 15.2%, 3.3%, and 3.2% (single 2.1% and multiple 1.1%), respectively. Younger age was associated with attempts and more strongly associated with multiple attempts. Attempts were the most strongly associated with mood disorders, especially bipolar disorder, which was more strongly associated with multiple attempts. In conclusion, suicidal behaviors are highly prevalent in Korea, especially in young adults. Bipolar disorder was the most strongly associated disorder with suicide attempts, more with multiple attempts. PMID:20823725

  19. 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.

  20. 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.

  1. Lifetime exposure to environmental lead and children's intelligence at 11-13 years: the Port Pirie cohort study.

    PubMed Central

    Tong, S.; Baghurst, P.; McMichael, A.; Sawyer, M.; Mudge, J.

    1996-01-01

    OBJECTIVE--To examine the association between environmental exposure to lead and children's intelligence at age 11-13 years, and to assess the implications of exposure in the first seven years of life for later childhood development. DESIGN--Prospective cohort study. SUBJECTS--375 children born in or around the lead smelting town of Port Pirie, Australia, between 1979 and 1982. MAIN OUTCOME MEASURE--Children's intelligence quotient (IQ) measured at 11-13 years of age. RESULTS--IQ was inversely associated with both antenatal and postnatal blood lead concentrations. Verbal, performance, and full scale IQ were inversely related to blood lead concentration with no apparent threshold. Multivariate analyses indicated that after adjustment for a wide range of confounders, the postnatal blood lead concentrations (particularly within the age range 15 months to 7 years) exhibited inverse associations with IQ. Strong associations with IQ were observed for lifetime average blood lead concentrations at various ages. The expected mean full scale IQ declined by 3.0 points (95% confidence interval 0.07 to 5.93) for an increase in lifetime average blood lead concentration from 0.48 to 0.96 mumol/l (10 to 20 micrograms/dl). CONCLUSION--Exposure to environmental lead during the first seven years of life is associated with cognitive deficits that seem to persist into later childhood. PMID:8664666

  2. 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.

  3. A theoretical study of microwave beam absorption by a rectenna

    NASA Technical Reports Server (NTRS)

    Ott, J. H.; Rice, J. S.; Thorn, D. C.

    1981-01-01

    The results of a theoretical study of microwave beam absorption by a Rectenna are given. Total absorption of the power beam is shown to be theoretically possible. Several improvements in the Rectenna design are indicated as a result of analytic modeling. The nature of Rectenna scattering and atmospheric effects are discussed.

  4. 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.

  5. 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.

  6. 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.

  7. Beam funneling studies at Los Alamos

    SciTech Connect

    Stovall, J.E.; Guy, F.W.; Stokes, R.H.; Wangler, T.P.

    1988-01-01

    Funneling two ion beams by interlacing their bunches can reduce the cost and complexity of systems producing intense beams. Applications of funneling could include accelerators for heavy ion inertial fusion, electronuclear breeding, and fusion materials irradiation. Funneling in an RFQ-like structure is an elegant solution at low energy where electric fields are needed to provide strong focusing. Discrete-element funnels, with separate focusing elements, bending magnets, rebunchers and if deflectors, are more flexible. At sufficiently high energies, magnetic-quadrupole lenses can provide strong focusing in a discrete-element funnel. Such a funnel has been designed as a preliminary example of a second funnel in the HIBALL-II accelerator system. In a simulation, two Bi/sup +1/ (mass = 209 amu) beams at 0.5 MeV/A, 20 MHz, 40-mA, separated by 55 cm and angled at +-6/degree/ were combined into a single 80-mA beam at 40 MHz. Emittance growth was calculated, by a modified version of the PIC (particle-in-cell) code PARMILA, to be about 1%. Funnel design experience at Los Alamos has evolved rules-of-thumb that reduce emittance growth. Some of these are to maintain focusing periodicity and strength in both transverse and longitudinal directions; use strong focusing so that the bunch will be small; minimize angles of bend and rf deflection; adjust longitudinal focusing to produce a short bunch at the rf deflector; and design rf deflectors for a uniform electrical field. 4 refs., 3 figs., 2 tabs.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Molecular beam studies of reaction dynamics

    SciTech Connect

    Lee, Y.T.

    1987-03-01

    Purpose of this research project is two-fold: (1) to elucidate detailed dynamics of simple elementary reactions which are theoretically important and to unravel the mechanism of complex chemical reactions or photo chemical processes which play an important role in many macroscopic processes and (2) to determine the energetics of polyatomic free radicals using microscopic experimental methods. Most of the information is derived from measurement of the product fragment translational energy and angular distributions using unique molecular beam apparati designed for these purposes.

  13. 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.

  14. Fluorescence lifetime distributions in proteins.

    PubMed Central

    Alcala, J. R.; Gratton, E.; Prendergast, F. G.

    1987-01-01

    The fluorescence lifetime value of tryptophan residues varies by more than a factor of 100 in different proteins and is determined by several factors, which include solvent exposure and interactions with other elements of the protein matrix. Because of the variety of different elements that can alter the lifetime value and the sensitivity to the particular environment of the tryptophan residue, it is likely that non-unique lifetime values result in protein systems. The emission decay of most proteins can be satisfactorily described only using several exponential components. Here it is proposed that continuous lifetime distributions can better represent the observed decay. An approach based on protein dynamics is presented, which provides fluorescence lifetime distribution functions for single tryptophan residue proteins. First, lifetime distributions for proteins interconverting between two conformations, each characterized by a different lifetime value, are derived. The evolution of the lifetime values as a function of the interconversion rate is studied. In this case lifetime distributions can be obtained from a distribution of rates of interconversion between the two conformations. Second, the existence of a continuum of energy substates within a given conformation was considered. The occupation of a particular energy substate at a given temperature is proportional to the Boltzmann factor. The density of energy states of the potential well depends upon the width of the well, which determines the degree of freedom the residue can move in the conformational space. Lifetime distributions can be obtained by association of each energy substate with a different lifetime value and assuming that the average conformation can change as the energy of the substate is increased. Finally, lifetime distributions for proteins interconverting between two conformations, each characterized by a quasi-continuum of energy substates, are presented. The origin of negative components

  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.

    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.

  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.; /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.

  17. 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.

  18. 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.

  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. PMID:21326305

  20. 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.

  1. Lifetime and twelve-month prevalence of heavy-drinking in Singapore: Results from a representative cross-sectional study

    PubMed Central

    2013-01-01

    Background The study aimed to establish the prevalence of heavy drinking, evaluate correlations between heavy drinking and socio-demographic factors, physical and psychiatric conditions, and assess the impact of heavy drinking on quality of life and days of work-loss. Methods Data from a nationally-representative cross-sectional sample were used. The sample comprised 6616 community-dwelling Singaporeans & Singapore Permanent Residents. The main instruments used were the World Mental Health Composite International Diagnostic Interview and EuroQol 5D. Heavy drinking was defined as consumption of 4 or more drinks, or 5 or more drinks in a day in women and men respectively. Results 12.6% of all adult Singapore residents reported heavy drinking in the last 12 months, and 15.9% reported lifetime heavy-drinking. Strong gender, ethnic, age and income differences were seen. Heavy drinking was positively associated with major depression, the presence of any mood disorder, and with chronic pain. It was also strongly associated with alcohol dependence, alcohol abuse, and nicotine dependence. Heavy-drinkers reported lower quality of life compared to non-heavy drinkers, measured using the EuroQol 5D Visual Analogue Scale. Conclusions Singapore has a relatively high prevalence of 12-month heavy drinking of 12.6%, and lifetime heavy drinking of 15.9%. Heavy drinking was positively associated with both physical and mental health conditions, and with declines in quality of life. Continued monitoring of heavy drinking behavior and sustained efforts to mitigate the risks associated with heavy drinking is needed. PMID:24499269

  2. 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.

  3. Lifetime Performance Studies on Vacuum Photo-Triodes in the ECAL at CMS

    NASA Astrophysics Data System (ADS)

    Wood, John

    2011-10-01

    The electromagnetic calorimeter (ECAL) is a crucial sub-detector of the Compact Muon Solenoid (CMS) at the Large Hadron Collider (LHC). It uses scintillation light fr om approximately 83,000 Lead Tungstate (PbWO4) crystals to make precision measurements of high energy photons and electrons. In the endcaps of the ECAL this scinti llation light is collected at the rear of the crystal and converted to an analog electric current with radiation hard, single stage photmultipliers known as Vacuum Pho to-Triodes (VPTs). The response of the VPTs is dependent on several effects including orientation within the magnetic field, calibration and scintillation light expos ure rates, and time between successive exposures. The High Energy Physics group at the University of Virginia (UVa) uses a 3.8 T large-bore superconducting solenoid m agnet to simulate conditions at the LHC and to study the long term behavior of these VPTs under various light and magnetic field conditions. Also, using the ECAL lase r and LED calibration system, UVa is also able to study the response of the VPTs in situ at the CMS detector in order to understand and quantitatively assess the perfo rmance of the VPTs over time. Herein we will report on these remote and in-situ studies of VPT characteristics and performance.

  4. Encountering abuse in health care; lifetime experiences in postnatal women - a qualitative study

    PubMed Central

    2013-01-01

    Background Abuse in health care (AHC) has been associated with potential severe health consequences, and has further been related to maternal morbidity and mortality in childbirth. To improve our understanding of what qualifies as AHC and to support and optimise the health of women with these experiences, the objective of this study was to describe how women, who had previously endured AHC, gave meaning to and managed their experience during pregnancy, childbirth, and in the early postnatal period. Method Women, who had reported substantial suffering as a result of a previous experience of abuse within the healthcare system, were purposefully selected from a Danish sample of a multinational cohort study on negative life events among pregnant women (the BIDENS Study). Eleven women were interviewed individually by means of a semi-structured interview guide. Transcripts of the interviews were analysed by means of qualitative systematic text condensation analysis. Results Four categories were identified to describe the women’s experience of AHC and its consequences on pregnancy and childbirth: abusive acts of unintentional harm, dehumanization, bodily remembrance, and finding the strength to move on. Abuse in health care may have profound consequences on the reproductive lives of the women, among others affecting sexuality, the desire to have children and the expectations of mode of delivery. However, the women described constructive ways to manage the experience, to which healthcare professionals could also contribute significantly. Conclusions Regardless of whether AHC is experienced in childhood or adulthood, it can influence the lives of women during pregnancy and childbirth. By recognising the potential existence of AHC, healthcare professionals have a unique opportunity to support women who have experienced AHC. PMID:23521853

  5. A Study on a Prognosis Algorithm for PEMFC Lifetime Prediction based on Durability Tests

    SciTech Connect

    Zhang, Xian; Pisu, Pierluigi; Toops, Todd J

    2010-01-01

    Of the fuel cells being studied, the proton exchange membrane fuel cell (PEMFC) is viewed as the most promising for transportation. Yet until today, the commercialization of the PEMFC has not been widespread in spite of its large expectation. Poor long term performances or durability, and high production and maintenance costs account for the main reasons. For the final commercialization of fuel cell in transportation field, the durability issue must be addressed, while the costs should be further brought down. In the meantime, health-monitoring and prognosis techniques are of great significance in ensuring the normal operation of the fuel cell and preventing or predicting its likely abrupt and catastrophic failure.

  6. Lifetime measurements in neutral alkalis

    NASA Astrophysics Data System (ADS)

    Diberardino, Diana

    1998-12-01

    Precision measurements of transition probabilities and energies provide a means for testing atomic structure calculations. The most accurate atomic structure calculations employ many-body perturbation theory (MBPT) and are used for the interpretation of atomic parity nonconservation (PNC) measurements and for testing of quantum electrodynamics (QED). Our group's measurement of the 6p/ 2P3/2,1/2 state lifetimes in atomic cesium provides constraints for recent MBPT calculations in cesium and electric dipole (E1) matrix elements. These E1 matrix elements contribute a large fraction to the weak-interaction-induced 6S[-]7S transition amplitude in cesium. Part of this thesis has been motivated by our desire to reduce the uncertainties in the measured 6p/ 2P3/2,1/2 state lifetimes in atomic cesium using improvements in our fast-beam apparatus. Thus, a new fiber optic detector system is designed to provide better collection efficiency and reduce beam tracking errors. Also, a new method of measuring the atomic beam velocity using a solid etalon is demonstrated to improve the velocity precision by a factor of seven. Additionally, this thesis describes measurements of the cesium 5d/ 2D5/2,/ 5d/ 2D3/2, and 11s/ 2S1/2 state lifetimes using pulsed-dye laser excitation of cesium vapor. The 5d/ 2D3/2 lifetime measurement, along with its branching ratio, provides the electric dipole reduced matrix element between the 5d/ 2D3/2 state and the 6p/ 2P1/2 state. Furthermore, a previous 5d/ 2D5/2 experimental value is compared with our new value and recent theoretical calculations.

  7. Optics Studies of the LHC Beam Transfer Line TI8

    SciTech Connect

    J. Wenninger; G. Arduini; B. Goddard; D. Jacquet; V. Kain; M. Lamont; V. Mertens; J.A. Uythoven; Y.-C. Chao

    2005-05-16

    The optics of the newly commissioned LHC beam transfer line TI 8 was studied with beam trajectories, dispersion and profile measurements. Steering magnet response measurements were used to analyze the quality of the steering magnets and of the beam position monitors. A simultaneous fit of the quadrupole strengths was used to search for setting or calibration errors. Residual coupling between the planes was evaluated using high statistics samples of trajectories. Initial conditions for the optics at the entrance of the transfer line were reconstructed from beam profile measurements with Optical Transition Radiation monitors. The paper presents the various analysis methods and their errors. The expected emittance growth arising from optical mismatch into the LHC is evaluated.

  8. Recent astrophysical studies with exotic beams at ORNL

    NASA Astrophysics Data System (ADS)

    Bardayan, D. W.

    2006-03-01

    The availability of exotic beams has produced great opportunities for advances in our understanding of the nucleosynthesis occurring in stellar burning and stellar explosions such as novae, X-ray bursts, and supernovae. In these extreme environments, synthesized radioactive nuclei can undergo subsequent nuclear processing before they decay, and thus to understand these events, we must understand reaction rates involving radioactive nuclei. At the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), we have made a number of measurements using proton-rich beams such as 18F and 7Be and neutron-rich beams such as 82Ge and 84Se that help clarify the structure of astrophysically-important nuclei. We are also poised to begin studies with doubly-magic 132Sn. The experimental methods and results are discussed.

  9. Recent Astrophysical Studies with Exotic Beams at ORNL

    SciTech Connect

    Bardayan, Daniel W

    2006-02-01

    The availability of exotic beams has produced great opportunities for advances in our understanding of the nucleosynthesis occurring in stellar burning and stellar explosions such as novae, X-ray bursts, and supernovae. In these extreme environments, synthesized radioactive nuclei can undergo subsequent nuclear processing before they decay, and thus to understand these events, we must understand reaction rates involving radioactive nuclei. At the ORNL Holi led Radioactive Ion Beam Facility (HRIBF), we have made several recent measurements using proton-rich beams such as 18F and 7Be and neutron-rich beams such as 82Ge and 84Se that help clarify the structure of astrophysically-important nuclei. We are also poised to begin studies with doubly-magic 132Sn. The experimental methods and results are discussed.

  10. Simulation studies of emittance growth in RMS mismatched beams

    SciTech Connect

    Cucchetti, A.; Wangler, T. ); Reiser, M. )

    1991-01-01

    As shown in a separate paper, a charged-particle beam, whose rms size is not matched when injected into a transport channel or accelerator, has excess energy compared with that of a matched beam. If nonlinear space-charge forces are present and the mismatched beam transforms to a matched equilibrium state, rms-emittance growth will occur. The theory yields formulas for the possible rms-emittance growth, but not for the time it takes to achieve this growth. In this paper we present the results of systematic simulation studies for a mismatched 2-D round beam in an ideal transport channel with continuous linear focusing. Emittance growth rates obtained from the simulations for different amounts of mismatch and initial charge will be presented and the emittance growth will be compared with the theory. 6 refs., 7 figs.

  11. Studies on the Effect of Temperature on Electroluminescence, Current-Voltage, and Carrier Lifetimes Characteristics in a InGaN/Sapphire Purple Light Emitting Diode

    NASA Astrophysics Data System (ADS)

    Dalapati, Pradip; Manik, Nabin Baran; Basu, Asok Nath

    2016-06-01

    In this report, we have measured electroluminescence (El), current-voltage, and effective carrier lifetime characteristics in a InGaN/Sapphire purple light emitting diode (UV3TZ-395-15) in the temperature range from 350 K to 77 K. The semiconductor rate equations have been employed to analyse the light-current data to determine the relation of radiative efficiency ( η r) of the device with injection current at different temperatures, which is found to reach nearly 100% at 77 K with 20 mA current. The same analysis simultaneously leads to an evaluation of the non-radiative carrier lifetime ( τ nr) of the device and its temperature dependence. Next, using the data on voltage gradient obtained from the open circuit voltage decay (OCVD) process, as well as those of ideality factor from the current-voltage characteristics, measurement the variations of the effective carrier lifetime ( τ eff) with injection current at different temperatures have been evaluated. From the values of τnr and τeff , we have calculated the temperature dependence of the radiative lifetime ( τ r) of carriers. Using the values of lifetimes it is shown that the internal quantum efficiency ( η i) of the diode increases with lowering of temperature and reaches its maximum at about 120 K. Finally, this comprehensive study, apart from being highly useful in various optoelectronic applications, contributes to clarify our understanding of the physical processes at work in the device.

  12. Transverse beam dynamics studies of a heavy ion induction linac

    SciTech Connect

    Garvey, T.; Eylon, S.; Fessenden, T.J.; Hahn, K.; Henestroza, E.; Keefe, D.

    1990-08-01

    The multiple beam induction linac experiment (MBE-4) was built to study the accelerator physics of the low energy, electrostatically focussed end of a driver for heavy ion inertial confinement fusion. In this machine four beams of Cs{sup +} ions are accelerated through 24 common induction gaps while being focussed in separate AG focussing channels. Each channel consists of a syncopated FODO lattice of 30 periods. We report results of the most recent studies of the transverse beam dynamics of a single drifting (180 keV) beam in this machine. The dependence of the emittance on the zero-current phase advance shows systematic variations which may be understood in the light of previous theoretical work on this topic. This result, unique to the beam parameters of a linac for heavy ion fusion, will be discussed in the context of its implications for a driver design. In addition we will discuss recent measurements of the motion of the beam centroid through the linac. These measurements, coupled with simulations, have proven to be a powerful tool in determining the presence of misalignment errors in the lattice of the accelerator. 6 refs., 3 figs.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. Singlet oxygen phosphorescence lifetime imaging based on a fluorescence lifetime imaging microscope.

    PubMed

    Tian, Wenming; Deng, Liezheng; Jin, Shengye; Yang, Heping; Cui, Rongrong; Zhang, Qing; Shi, Wenbo; Zhang, Chunlei; Yuan, Xiaolin; Sha, Guohe

    2015-04-01

    The feasibility of singlet oxygen phosphorescence (SOP) lifetime imaging microscope was studied on a modified fluorescence lifetime imaging microscope (FLIM). SOP results from the infrared radiative transition of O2(a(1)Δg → X(3)Σg(-)) and O2(a(1)Δg) was produced in a C60 powder sample via photosensitization process. To capture the very weak SOP signal, a dichroic mirror was placed between the objective and tube lens of the FLIM and used to divide the luminescence returning from the sample into two beams: the reflected SOP beam and the transmitted photoluminescence of C60 (C60-PL) beam. The C60-PL beam entered the scanner of the FLIM and followed the normal optical path of the FLIM, while the SOP steered clear of the scanner and directly entered a finely designed SOP detection channel. Confocal C60-PL images and nonconfocal SOP images were then simultaneously obtained by using laser-scanning mode. Experimental results show that (1) under laser-scanning mode, the obstacle to confocal SOP imaging is the infrared-incompatible scanner, which can be solved by using an infrared-compatible scanner. Confocal SOP imaging is also expected to be realized under stage-scanning mode when the laser beam is parked and meanwhile a pinhole is added into the SOP detection channel. (2) A great challenge to SOP imaging is its extraordinarily long imaging time, and selecting only a few interesting points from fluorescence images to measure their SOP time-dependent traces may be a correct compromise. PMID:25781060

  18. EXPERIMENTAL STUDY OF PROTON-BEAM HALO INDUCED BY BEAM MISMATCH IN LEDA.

    SciTech Connect

    Wangler, Thomas P.,; Allen, C. K.; Colestock, P. L. ,; Chan, K. D.; Crandall, K. R.; Garnett, R. W.; Gilpatrick, J. D.; Lysenko, W. P.; Qiang, J.; Schneider, J. D.; Sheffield, R. L.; Smith, H. V.; Schulze, M. E.

    2001-01-01

    We report measurements of transverse beam halo in mismatched proton beams in a 52-quadrupole FODO transport channel following the 6.7-MeV LEDA RFQ. Beam profiles in both transverse planes are measured using beam-profile diagnostic devices that consist of a movable carbon filament for measurement of the dense beam core, and scraper plates for measurement of the halo. The gradients of the first four quadrupoles can be independently adjusted to mismatch the RFQ output beam into the beam-transport channel. The properties of the measured mismatched beam profiles in the transport channel will be compared with predictions from multiparticle beam-dynamics simulations.

  19. 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

  20. 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.

  1. Nuclear photofission studies with monochromatic γ ray beams

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    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 γ beams with so far unprecedented properties via Compton backscattering of laser photons from a high-quality, relativistic electron beam. With these intense, monochromatic γ 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 γ beams on highly-selective studies of extremely deformed nuclei in the multiple-humped potential energy landscape of the actinides via photofission. With the unique γ beam bandwidth of ΔE/E = 10-3, we can aim at resolving individual resonances which could never be achieved so far due to the limited γ bandwidth of bremsstrahlung beams. Exploratory, non-bremsstrahlung photofission experiments are going to be performed very soon at the HIγS facility (Duke University, USA) to investigate the fine structure of the sub-barrier transmission resonances of the actinides.

  2. 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.

  3. 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.

  4. Lifetime hypertension as a predictor of brain structure in older adults: cohort study with a 28-year follow-up

    PubMed Central

    Allan, Charlotte L.; Zsoldos, Enikõ; Filippini, Nicola; Sexton, Claire E.; Topiwala, Anya; Valkanova, Vyara; Singh-Manoux, Archana; Tabák, Adam G.; Shipley, Martin J.; Mackay, Clare; Ebmeier, Klaus P.; Kivimäki, Mika

    2015-01-01

    Background Hypertension is associated with an increased risk of dementia and depression with uncertain longitudinal associations with brain structure. Aims To examine lifetime blood pressure as a predictor of brain structure in old age. Method A total of 190 participants (mean age 69.3 years) from the Whitehall II study were screened for hypertension six times (1985–2013). In 2012–2013, participants had a 3T-magnetic resonance imaging (MRI) brain scan. Data from the MRI were analysed using automated and visual measures of global atrophy, hippocampal atrophy and white matter hyperintensities. Results Longitudinally, higher mean arterial pressure predicted increased automated white matter hyperintensities (P<0.002). Cross-sectionally, hypertensive participants had increased automated white matter hyperintensities and visually rated deep white matter hyperintensities. There was no significant association with global or hippocampal atrophy. Conclusions Long-term exposure to high blood pressure predicts hyperintensities, particularly in deep white matter. The greatest changes are seen in those with severe forms of hypertension, suggesting a dose–response pattern. PMID:25497301

  5. 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.

  6. Lifetime criminality among boys with ADHD: a prospective follow-up study into adulthood using official arrest records

    PubMed Central

    Mannuzza, Salvatore; Klein, Rachel G.; Moulton, John L.

    2008-01-01

    This study investigates the relationship between childhood attention deficit hyperactivity disorder (ADHD) and later criminality. White boys (n = 207, ages 6–12) with ADHD, free of conduct disorder, were assessed at ages 18 and 25 by clinicians who were blind to childhood status. A non-ADHD group served as comparisons. Lifetime arrest records were obtained when subjects were 38 years old for subjects who resided in New York State throughout the follow-up interval (93 probands, 93 comparisons). Significantly more ADHD probands than comparisons had been arrested (47% vs. 24%), convicted (42% vs. 14%), and incarcerated (15% vs. 1%). Rates of felonies and aggressive offenses also were significantly higher among probands. Importantly, the development of an antisocial or substance use disorder in adolescence completely explained the increased risk for subsequent criminality. Results suggest that even in the absence of comorbid conduct disorder in childhood, ADHD increases the risk for developing antisocial and substance use disorders in adolescence, which, in turn, increases the risk for criminal behavior in adolescence and adulthood. PMID:18707766

  7. 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.

  8. Beam-beam instability

    SciTech Connect

    Chao, A.W.

    1983-08-01

    The subject of beam-beam instability has been studied since the invention of the colliding beam storage rings. Today, with several colliding beam storage rings in operation, it is not yet fully understood and remains an outstanding problem for the storage ring designers. No doubt that good progress has been made over the years, but what we have at present is still rather primitive. It is perhaps possible to divide the beam-beam subject into two areas: one on luminosity optimization and another on the dynamics of the beam-beam interaction. The former area concerns mostly the design and operational features of a colliding beam storage ring, while the later concentrates on the experimental and theoretical aspects of the beam-beam interaction. Although both areas are of interest, our emphasis is on the second area only. In particular, we are most interested in the various possible mechanisms that cause the beam-beam instability.

  9. 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

  10. Beam-blowup study for a weak-strong case

    SciTech Connect

    Kheifets, S.; Helm, R.; Shoaee, H.

    1983-07-01

    A comparison is made of experimental results obtained on two SLAC storage rings PEP and SPEAR with the theoretical calculations and the dependence of the phenomenon on different machine parameters is studied. In the present paper we present such a comparison with reasonably good agreement between the experiment and the theory. The important conclusion from our study is that any valid theory of the beam-beam phenomenon should take into account the asymmetries of the machine parameters arising in any storage ring from all kinds of machine imperfections.