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Sample records for beta-delayed proton emitters

  1. Extension of the Tz = -3/2, A = 4n + 1 series of beta-delayed proton emitters to 65Se and 73Sr, and low energy beta-delayed proton emission from the Tz = -3/2, A = 4n + 3 nucleus 23Al

    SciTech Connect

    Batchelder, Jon Charles

    1993-12-01

    The series of known Tz = -3/2, A = 4n + 1 nuclei has been extended to include the previously undiscovered isotopes 65Se and 73Sr, through the observation of beta-delayed proton emission via the isobaric analog state (IAS) of the beta-daughter (emitter). Due to the relatively large proton energies involved, these experiments were conducted using standard Si-Si ΔE-E telescopes. Beta-delayed protons arising from 65Se have been observed at an energy (laboratory) of 3.55 ± 0.03 MeV, corresponding to the decay of the T = 3/2 isobaric analog state in 65As to the ground state of 64Ge. Similarly, beta-delayed protons from 73Sr at an energy of 3.75 ± 0.04 MeV have been observed, corresponding to decay of the T = 3/2 isobaric analog state in 73Rb to the ground state of 72Kr. From the energies of these proton transitions, an improved prediction of the mass excesses of the two parent nuclei (65Se and 73Sr) is made through the use of a Coulomb displacement formula. These predictions are -33.41 ± 0.26 and -31.87 ± 0.24 MeV for 65Se and 73Sr, respectively. Studies of low energy (down to ~200 keV) beta-delayed protons from 23Al necessitated that a particle identification telescope with a low energy threshold for observation and identification of protons be developed. 23Al is of interest because of its role in the breakout of the hot CNO cycle leading to the astrophysical rp process.

  2. New {beta}-delayed proton precursor {sup 121}Ce

    SciTech Connect

    Zhankui, L.; Shuwei, X.; Yuanxiang, X.; Ruichang, M.; Yuanxiu, G.; Chunfang, W.; Wenxue, H.; Tianmei, Z.

    1997-08-01

    The new {beta}-delayed proton precursor {sup 121}Ce was synthesized in the reaction {sup 92}Mo({sup 32}S,3n) and first identified in p-{gamma}(X) coincidence measurements with a helium-jet recoil fast-moving tape-transport system. The half-life of the {sup 121}Ce decay was determined to be 1.1{plus_minus}0.1 s. Its {beta}-delayed proton spectrum was observed and the {beta}-delayed proton branching ratio for {sup 121}Ce decay was estimated to be {approximately}1{percent}. {copyright} {ital 1997} {ital The American Physical Society}

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

    SciTech Connect

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

    2005-05-01

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

  4. Beta-delayed proton emission from 20Mg

    NASA Astrophysics Data System (ADS)

    Lund, M. V.; Andreyev, A.; Borge, M. J. G.; Cederkäll, J.; De Witte, H.; Fraile, L. M.; Fynbo, H. O. U.; Greenlees, P. T.; Harkness-Brennan, L. J.; Howard, A. M.; Huyse, M.; Jonson, B.; Judson, D. S.; Kirsebom, O. S.; Konki, J.; Kurcewicz, J.; Lazarus, I.; Lica, R.; Lindberg, S.; Madurga, M.; Marginean, N.; Marginean, R.; Marroquin, I.; Mihai, C.; Munch, M.; Nacher, E.; Negret, A.; Nilsson, T.; Page, R. D.; Pascu, S.; Perea, A.; Pucknell, V.; Rahkila, P.; Rapisarda, E.; Riisager, K.; Rotaru, F.; Sotty, C.; Stanoiu, M.; Tengblad, O.; Turturica, A.; Van Duppen, P.; Vedia, V.; Wadsworth, R.; Warr, N.

    2016-10-01

    Beta-delayed proton emission from 20 Mg has been measured at ISOLDE, CERN, with the ISOLDE Decay Station (IDS) setup including both charged-particle and gamma-ray detection capabilities. A total of 27 delayed proton branches were measured including seven so far unobserved. An updated decay scheme, including three new resonances above the proton separation energy in 20 Na and more precise resonance energies, is presented. Beta-decay feeding to two resonances above the Isobaric Analogue State (IAS) in 20 Na is observed. This may allow studies of the 4032.9(2.4)keV resonance in 19 Ne through the beta decay of 20 Mg, which is important for the astrophysically relevant reaction 15O( α, γ)19Ne . Beta-delayed protons were used to obtain a more precise value for the half-life of 20 Mg, 91.4(1.0)ms.

  5. Study of beta-delayed two-proton emission in /sup 22/Al and /sup 26/P and search for new emitters

    SciTech Connect

    Cable, M.D.; Honkanen, J.; Schloemer, E.C.; Ahmed, M.; Reiff, J.E.; Zhou, Z.Y.; Cerny, J.

    1984-04-01

    As predicted by Gol'danskii, nuclei far from stability may decay via the unusual manner of /sup 2/He (or 'diproton') emission. The diproton corresponds to a coupling of two protons in a virtual /sup 1/S/sub 0/ state which subsequently decays to two unbound protons. This /sup 2/He nucleus has been calculated to have an increased probability of barrier penetration relative to the independent emission of two protons. When the energetics permit /sup 2/He emission, two competing modes of two-proton emission are also frequently allowed. These are a sequential proton decay through an intermediate state and the simultaneous emission of two uncoupled protons. Recent studies on /sup 22/Al and /sup 26/P are described and proposed partial decay schemes are given. (WHK)

  6. {beta}-delayed proton decay of {sup 69}Kr

    SciTech Connect

    Xu, X.J.; Huang, W.X.; Ma, R.C.; Gu, Z.D.; Yang, Y.F.; Wang, Y.Y.; Dong, C.F.; Xu, L.L.

    1997-02-01

    The nuclide {sup 69}Kr with T{sub z}={minus}3/2, A=4n+1 produced in the {sup 40}Ca({sup 32}S,3n) reaction has been observed via {beta}-delayed proton emission by using pulsed-beam technique. A single proton group at a laboratory energy of 4.07{plus_minus}0.05 MeV with half-life of 32{plus_minus}10 ms was observed for the first time, corresponding to decay of the T=3/2 isobaric analog state in {sup 69}Br to the ground state of {sup 68}Se. Combining this result with a Coulomb displacement energy calculation yields a mass excess for {sup 69}Kr of {minus}32.15{plus_minus}0.30 MeV. The partial decay scheme of {sup 69}Kr is proposed. {copyright} {ital 1997} {ital The American Physical Society}

  7. {beta}-delayed proton decays in the rare-earth region near drip line

    SciTech Connect

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

    2006-11-02

    The history of experimental study on {beta}-delayed proton decays in the rare-earth region was simply reviewed. The physical results of the {beta}-delayed proton decays obtained at IMP, Lanzhou over the last 10 years were summarized, mainly including the first observation of 9 new {beta}-delayed proton precursors along the odd-Z proton drip line and the new data for 2 waiting-point nuclei in the rp-process. The results were compared and discussed with different nuclear model calculations. Finally, the perspective in near future was briefly introduced.

  8. Beta-delayed two-proton emission as a nuclear probe

    SciTech Connect

    Moltz, D.M.; Reiff, J.E.; Robertson, J.D.; Lang, T.F.; Cerny, J.

    1987-09-01

    A brief history of beta-delayed two-proton emission is given. Speculations about future experiments which would enhance our knowledge about both nuclear spectroscopy and this relatively unique decay mode are presented. 16 refs., 7 figs.

  9. Proton branching ratios in the {beta}-delayed proton decay of {sup 87}Mo

    SciTech Connect

    Huang, W.X.; Ma, R.C.; Xu, X.J.; Xu, S.W.; Xie, Y.X.; Li, Z.K.; Ge, Y.X.; Wang, Y.Y.; Wang, C.F.; Zhang, T.M.; Sun, X.F.; Jin, G.M.; Luo, Y.X.

    1997-08-01

    The nuclide {sup 87}Mo with A=4n+3 and T{sub z}=3/2 was reinvestigated via its {beta}-delayed proton decay with p-{gamma} coincidence. The proton branching ratios in the decay of {sup 87}Mo populating the first 2{sup +}, 4{sup +}, and 6{sup +} excited states in {sup 86}Zr have been measured to be (11{plus_minus}6){percent}, (2{plus_minus}1){percent}, and (2{plus_minus}1){percent}, respectively, which revise the previous results. {copyright} {ital 1997} {ital The American Physical Society}

  10. Beta-delayed neutron spectroscopy of spherical and deformed neutron emitters with VANDLE

    NASA Astrophysics Data System (ADS)

    King, Thomas; Gross, C. J.; Grzywacz, R. K.; Paulauskas, S. V.; Rykaczewski, K. P.; Stracener, D. W.,; Taylor, S. Z.; Vandle Collaboration

    2016-09-01

    For many neutron-rich isotopes, the main decay mode is through beta-delayed neutron and gamma emission. Neutron and gamma coincidences provide information necessary to extract the beta-strength distribution. These distributions are inputs to test nuclear models needed for r-process modeling. The detailed data on beta decay feeding to neutron-unbound states are used to calculate reactor decay heat and understand the antineutrino spectrum. A series of measurements with selective ion sources was performed at the On-Line Test Facility (OLTF) at Oak Ridge National Laboratory with the Versatile Array of Neutron Detectors at Low Energy (VANDLE). These experiments revisited decays of spherical and deformed isotopes produced in proton induced fission of 238U, which included beta delayed precursors of bromine, rubidium, cesium, and iodine. Unique data sets with neutron and gamma ray coincidences were collected. Achieving high coincidence efficiency required the addition of high-efficiency gamma-ray detectors consisting of 16 LaBr3 crystals (HAGRiD) and a large volume set of NaI detectors to VANDLE. Preliminary results will be presented. This research was sponsored by DOE under Contracts DE-FG52-08NA2855, DE-AC05-00OR22725 and DE-FG02-96ER40983.

  11. Experimental study on {beta}-delayed proton decays in the rare-earth region near drip line

    SciTech Connect

    Xu, S.-W.; Li, Z.-K.; Xie, Y.-X.

    2007-11-30

    The history of experimental study on {beta}-delayed proton decays in the rare-earth region was simply reviewed. The physical results of the {beta}-delayed proton decays obtained at IMP, Lanzhou over the last 10 years were summarized, mainly including the first observation of 9 new {beta}-delayed proton precursors along the odd-Z proton drip line and the new data for 2 waiting-point nuclei in the rp-process. The results were compared and discussed with different nuclear model calculations. Finally, the perspective in near future was briefly introduced.

  12. Beta-delayed proton emission in neutron-deficient lanthanide isotopes

    SciTech Connect

    Wilmarth, P.A.

    1988-09-30

    Forty-two ..beta..-delayed proton precursors with 56less than or equal toZless than or equal to71 and 63less than or equal toNless than or equal to83 were produced in heavy-ion reactions at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decay properties studied at the on-line mass separation facility OASIS. Twenty-five isotopes and eight delayed proton branches were identified for the first time. Delayed proton energy spectra and proton coincident ..gamma..-ray and x-ray spectra were measured for all precursors. In a few cases, proton branching ratios were also determined. The precursor mass numbers were determined by the separator, while the proton coincident x-ray energies provided unambiguous Z identifications. The proton coincident ..gamma..-ray intensities were used to extract final state branching ratios. Proton emission from ground and isomeric states was observed in many cases. The majority of the delayed proton spectra exhibited the smooth bell-shaped distribution expected for heavy mass precursors. The experimental results were compared to statistical model calculations using standard parameter sets. Calculations using Nilsson model/RPA ..beta..-strength functions were found to reproduce the spectral shapes and branching ratios better than calculations using either constant or gross theory ..beta..-strength functions. Precursor half-life predictions from the Nilsson model/RPA ..beta..-strength functions were also in better agreement with the measured half-lives than were gross theory predictions. The ratios of positron coincident proton intensities to total proton intensities were used to determine Q/sub EC/-B/sub p/ values for several precursors near N=82. The statistical model calculations were not able to reproduce the experimental results for N=81 precursors. 154 refs., 82 figs., 19 tabs.

  13. Experimental study of {beta}-delayed proton decay of {sup 23}Al for nucleosynthesis in novae

    SciTech Connect

    Saastamoinen, A.; Aeystoe, J.; Trache, L.; Banu, A.; Hardy, J. C.; Iacob, V. E.; McCleskey, M.; Roeder, B. T.; Simmons, E.; Tabacaru, G.; Tribble, R. E.; Bentley, M. A.; Davinson, T.; Woods, P. J.

    2011-04-15

    The {beta}-delayed {gamma} and proton decay of {sup 23}Al has been studied with an alternative detector setup at the focal plane of the momentum achromat recoil separator MARS at Texas A and M University. We could detect protons down to an energy of 200 keV and determine the corresponding branching ratios. Contrary to results of previous {beta}-decay studies, no strong proton intensity from the decay of the isobaric analog state (IAS) of the {sup 23}Al ground state at E{sub x}=7803 keV in {sup 23}Mg was observed. Instead we assign the observed low-energy group E{sub p,c.m.}=206 keV to the decay from a state that is 16 keV below the IAS. We measured both proton and gamma branches from the decay of this state at E{sub x}=7787 keV in {sup 23}Mg, which is a very rare case in the literature. Combining our data with its measured lifetime, we determine its resonance strength to be {omega}{gamma}=1.4{sub -0.4}{sup +0.5} meV. The value is in agreement with older direct measurements, but disagrees with a recent direct measurement. This state is the most important resonance for the radiative proton capture {sup 22}Na(p,{gamma}){sup 23}Mg in some astrophysical environments, such as novae.

  14. THEORY OF PROTON EMITTERS

    SciTech Connect

    P. TALOU

    2000-08-01

    Modern theoretical methods used to interpret recent experimental data on ground-state proton emission near the proton drip line are reviewed. Most of them are stationary and are aimed to compute proton decay widths {Gamma}{sub p} only. Comparison is made between these approaches before being compared to experimental data. Our time-dependent approach based on the numerical solution of the time-dependent Schroedinger equation (TDSE) for initial quasi-stationary single-proton states is then introduced. It is shown that much deeper insights into the physics of this clean multidimensional quantum tunneling effect can be accessed, and that in addition to {Gamma}{sub p}, other physical quantities could be tested experimentally, offering new stringent tests on nuclear physics models away from the valley of {beta}-stability. Finally, the necessity of using the TDSE approach in more complex, dynamical, problems is demonstrated.

  15. Decays of /sup 22/Al and /sup 26/P: discovery of beta-delayed two-proton radioactivity

    SciTech Connect

    Cable, M.D.

    1983-02-01

    A helium-jet system and the /sup 24/Mg(/sup 3/He,p4n)/sup 22/Al and /sup 28/Si(/sup 3/He,p4n)/sup 26/P reactions have been used to discover the only known odd-odd, T/sub Z/ = -2 nuclides, /sup 22/Al(t/sub 1/2/ approx. 70ms) and /sup 26/P(t/sub 1/2/ approx. 20 ms). Observations of beta-delayed protons from each isotope (laboratory energies 7.839 +- 0.015 MeV and 8.149 +- 0.021 MeV for /sup 22/Al and 7.269 +- 0.015 MeV and 6.827 +- 0.050 MeV for /sup 26/P) established the existence of these nuclides and provided a measurement of the mass excesses of the lowest T = 2 states in their beta decay daughters, /sup 22/Mg and /sup 26/Si (13.650 +- 0.015 MeV and 5.936 +- 0.015 MeV, respectively). Measurement of these masses confirmed that these T = 2 states were unbound to two-proton emission as had been predicted theoretically.

  16. New strongly deformed proton emitter: 117La

    NASA Astrophysics Data System (ADS)

    Soramel, F.; Guglielmetti, A.; Stroe, L.; Müller, L.; Bonetti, R.; Poli, G. L.; Malerba, F.; Bianchi, E.; Andrighetto, A.; Guo, J. Y.; Li, Z. C.; Maglione, E.; Scarlassara, F.; Signorini, C.; Liu, Z. H.; Ruan, M.; Ivaşcu, M.; Broude, C.; Bednarczyk, P.; Ferreira, L. S.

    2001-03-01

    The decay by proton emission of the 117La nucleus has been studied via the 310 MeV 58Ni+64Zn reaction. The nucleus has two levels that decay to the ground state of 116Ba with Ep=783(6) keV (T1/2=22(5) ms] and Ep=933(10) keV [T1/2=10(5) ms]. Calculations performed for a deformed proton emitter reproduce quite well the experimental results confirming that 117La is strongly deformed (β2~0.3). Spin and parity of the two p-decaying levels have been determined as well: 3/2+ for the ground state and 9/2+ for the Ex=151(12) keV excited state.

  17. Improvements to the on-line mass separator, RAMA, and the beta-delayed charged-particle emission of proton-rich sd shell nuclei

    SciTech Connect

    Ognibene, Theodore Joseph

    1996-03-01

    To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of 31Cl, 27P and 28P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas ΔE-gas ΔE-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in 31Cl and 27P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of 31Cl were shown to be from the decay of 25Si. In 27P, two proton groups at 459 ± 14 keV and 610 ± 11 keV, with intensities of 7 ± 3% and 92 ± 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the β-decay of 28P, at 1,444 ± 12 keV with a 1.7 ± 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, 17Ne and 33Ar, were studied. A new proton group with energy 729 ± 15 keV was observed following the beta-decay of 17Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from 17Ne and 33Ar were resolved.

  18. Unique decay process: {beta}-delayed emission of a proton and a neutron by the {sup 11}Li halo nucleus

    SciTech Connect

    Baye, D.; Descouvemont, P.; Tursunov, E. M.

    2010-11-15

    The neutron-rich {sup 11}Li halo nucleus is unique among nuclei with known separation energies in its ability to emit a proton and a neutron in a {beta}-decay process. The branching ratio toward this rare decay mode is evaluated within a three-body model for the initial bound state and with Coulomb three-body final scattering states. The branching ratio should be comprised between two extreme cases, i.e., a lower bound 6x10{sup -12} obtained with a pure Coulomb wave and an upper bound 5x10{sup -10} obtained with a plane wave. A simple model with modified Coulomb waves provides plausible values between 0.8x10{sup -10} and 2.2x10{sup -10}, with most probable total energies of the proton and neutron between 0.15 and 0.3 MeV.

  19. Odd-odd deformed proton emitters.

    PubMed

    Ferreira, L S; Maglione, E

    2001-02-26

    Proton decay from odd-odd deformed nuclei is a long-standing unsolved problem. We present for the first time an exact solution using single particle Nilsson resonances. The lifetime is found to depend strongly on the single particle level occupied by the unpaired neutron, allowing a clear assignment of its Nilsson level. The emitters 112Cs, 140Ho, 150Lu, and 150Lu(m) are considered. The agreement with the experimental data is very good with deformations 0.1

  20. Emittance growth mechanisms for laser-accelerated proton beams.

    PubMed

    Kemp, Andreas J; Fuchs, J; Sentoku, Y; Sotnikov, V; Bakeman, M; Antici, P; Cowan, T E

    2007-05-01

    In recent experiments the transverse normalized rms emittance of laser-accelerated MeV ion beams was found to be < 0.002 mm mrad, which is at least 100 times smaller than the emittance of thermal ion sources used in accelerators [T. E. Cowan, Phys. Rev. Lett. 92, 204801 (2004)]. We investigate the origin for the low emittance of laser-accelerated proton beams by studying several candidates for emittance-growth mechanisms. As our main tools, we use analytical models and one- and two-dimensional particle-in-cell simulations that have been modified to include binary collisions between particles. We find that the dominant source of emittance is filamentation of the laser-generated hot electron jets that drive the ion acceleration. Cold electron-ion collisions that occur before ions are accelerated contribute less than ten percent of the final emittance. Our results are in qualitative agreement with the experiment, for which we present a refined analysis relating emittance to temperature, a better representative of the fundamental beam physics.

  1. Emittance measurements from the LLUMC proton accelerator

    NASA Astrophysics Data System (ADS)

    Coutrakon, G.; Gillespie, G. H.; Hubbard, J.; Sanders, E.

    2005-12-01

    A new method of calculating beam emittances at the extraction point of a particle accelerator is presented. The technique uses the optimization programs NPSOL and MINOS developed at Stanford University in order to determine the initial values of beam size, divergence and correlation parameters (i.e. beam sigma matrix, σij) that best fit measured beam parameters. These σij elements are then used to compute the Twiss parameters α, β, and the phase space area, ε, of the beam at the extraction point. Beam size measurements in X and Y throughout the transport line were input to the optimizer along with the magnetic elements of bends, quads, and drifts. The σij parameters were optimized at the accelerator's extraction point by finding the best agreement between these measured beam sizes and those predicted by TRANSPORT. This expands upon a previous study in which a "trial and error" technique was used instead of the optimizer software, and which yielded similar results. The Particle Beam Optics Laboratory (PBO Lab™) program used for this paper integrates particle beam optics and other codes into a single intuitive graphically-based computing environment. This new software provides a seamless interface between the NPSOL and MINOS optimizer and TRANSPORT calculations. The results of these emittance searches are presented here for the eight clinical energies between 70 and 250 MeV currently being used at LLUMC.

  2. a New Strongly Deformed Proton-Emitter 117La

    NASA Astrophysics Data System (ADS)

    Soramel, F.; Guglielmetti, A.; Bonetti, R.; Poli, G. L.; Malerba, F.; Bianchi, E.; Stroe, L.; Müller, L.; Andrighetto, A.; Guo, J. Y.; Li, Z. C.; Maglione, E.; Scarlassara, F.; Signorini, C.; Liu, Z. H.; Ruan, M.; Ivascu, M.; Broude, C.; Ferreira, L. S.

    2001-11-01

    The decay by proton emission of the 117La nucleus has been studied via the 310 MeV 58Ni + 64Zn reaction. The nucleus has two levels that decay to the ground state of 116Ba with Ep = 783(6) keV (T1/2 = 20(5) ms) and Ep = 933(10) keV (T1/2 = 10(5) ms). Calculations done for a deformed proton emitter reproduce the experimental results confirming that 117La is well deformed (β2 ~ 0.3).

  3. Monte Carlo calculations of positron emitter yields in proton radiotherapy.

    PubMed

    Seravalli, E; Robert, C; Bauer, J; Stichelbaut, F; Kurz, C; Smeets, J; Van Ngoc Ty, C; Schaart, D R; Buvat, I; Parodi, K; Verhaegen, F

    2012-03-21

    Positron emission tomography (PET) is a promising tool for monitoring the three-dimensional dose distribution in charged particle radiotherapy. PET imaging during or shortly after proton treatment is based on the detection of annihilation photons following the ß(+)-decay of radionuclides resulting from nuclear reactions in the irradiated tissue. Therapy monitoring is achieved by comparing the measured spatial distribution of irradiation-induced ß(+)-activity with the predicted distribution based on the treatment plan. The accuracy of the calculated distribution depends on the correctness of the computational models, implemented in the employed Monte Carlo (MC) codes that describe the interactions of the charged particle beam with matter and the production of radionuclides and secondary particles. However, no well-established theoretical models exist for predicting the nuclear interactions and so phenomenological models are typically used based on parameters derived from experimental data. Unfortunately, the experimental data presently available are insufficient to validate such phenomenological hadronic interaction models. Hence, a comparison among the models used by the different MC packages is desirable. In this work, starting from a common geometry, we compare the performances of MCNPX, GATE and PHITS MC codes in predicting the amount and spatial distribution of proton-induced activity, at therapeutic energies, to the already experimentally validated PET modelling based on the FLUKA MC code. In particular, we show how the amount of ß(+)-emitters produced in tissue-like media depends on the physics model and cross-sectional data used to describe the proton nuclear interactions, thus calling for future experimental campaigns aiming at supporting improvements of MC modelling for clinical application of PET monitoring.

  4. Spectroscopic studies near the proton drip line

    SciTech Connect

    Toth, K.S. ); Moltz, D.M.; Nitschke, J.M.; Wilmarth, P.A. ); Robertson, J.D. )

    1990-01-01

    We have investigated nuclei close to the proton drip line by using heavy-ion fusion reactions to produce extremely neutron-deficient nuclides. Their nuclear decay properties were studied by using on-line isotope separators at Oak Ridge (UNISOR) and Berkeley (OASIS), the Oak Ridge National Laboratory velocity filter, and a fast helium-gas-jet transport system at Lawrence Berkeley Laboratory 88-Inch Cyclotron. Many isotopes, isomers, and {beta}-delayed-proton and {alpha}-particle emitters were discovered. This contribution summarizes three topics that are part of our overall program: decay rates of even-even {alpha}-particle emitters, mass excesses of {sup 181}Pb, {sup 182}Pb, and {sup 183}Pb, and {beta}-delayed proton emitters near N = 82. 14 refs., 6 figs.

  5. First direct observation of two protons in the decay of 45Fe with a time-projection chamber.

    PubMed

    Giovinazzo, J; Blank, B; Borcea, C; Canchel, G; Dalouzy, J-C; Demonchy, C E; de Oliveira Santos, F; Dossat, C; Grévy, S; Hay, L; Huikari, J; Leblanc, S; Matea, I; Pedroza, J-L; Perrot, L; Pibernat, J; Serani, L; Stodel, C; Thomas, J-C

    2007-09-07

    The decay of the ground-state two-proton emitter 45Fe was studied with a time-projection chamber and the emission of two protons was unambiguously identified. The total decay energy and the half-life measured in this work agree with the results from previous experiments. The present result constitutes the first direct observation of the individual protons in the two-proton decay of a long-lived ground-state emitter. In parallel, we identified for the first time directly two-proton emission from 43Cr, a known beta-delayed two-proton emitter. The technique developed in the present work opens the way to a detailed study of the mechanism of ground state as well as beta-delayed two-proton radioactivity.

  6. Beta delayed alpha emission from the neutron deficient rare earth isotopes {sup 152}Tm and {sup 150}Ho

    SciTech Connect

    Nacher, E.; Tain, J. L.; Rubio, B.; Algora, A.; Estevez Aguado, M. E.; Gadea, A.; Batist, L.; Briz, J. A.; Cano-Ott, D.; Doering, J.; Mukha, I.; Plettner, C.; Roeckl, E.; Gierlik, M.; Janas, Z.

    2011-11-30

    The study of beta-delayed proton emission is a well known method to aid the determination of the beta strength distribution in nuclei far from the stability line. At the neutron deficient side of the nuclear chart the process of proton or alpha emission from excited states is energetically allowed when one goes far enough from stability. However, beta-delayed alphas have seldom been measured for nuclei heavier than A = 20. Here we present a study of the beta-delayed alpha-particle emission from {sup 152}Tm and {sup 150}Ho and their importance in the full B(GT) distribution.

  7. Improvement of beam emittance of the CEA high intensity proton source SILHI

    NASA Astrophysics Data System (ADS)

    Gobin, R.; Beauvais, P.-Y.; Ferdinand, R.; Leroy, P.-A.; Celona, L.; Ciavola, G.; Gammino, S.

    1999-06-01

    The emittance of the intense proton beam extracted by the source SILHI at Commisariat à l'Energie Atomique (CEA)-Saclay is a key parameter for the design of the IPHI Project RFQ. This parameter has a relevant role even for the design of an intense proton source for the TRASCO project of Istituto Nazionale di Fisica Nucleare (INFN). The tests performed in the framework of CEA-INFN collaboration have been mainly devoted to a 75 mA beam emittance investigation injecting different gases in the beam line. The results show that the rms normalized emittance decreases up to a factor 3 while the beam losses induced by recombination are contained within 5%. Normalized emittance in r-r' plane of about 0.1 π min mrad have been obtained using Ar and Kr.

  8. Half-life calculation of one-proton emitters with a shell model potential

    SciTech Connect

    Rodrigues, M. M.; Duarte, S. B.

    2013-03-25

    The accumulated amount of data for half-lives of proton emitters still remains a challenge to the ability of nuclear models to reproduce them consistently. These nuclei are far from beta stability line in a region where the validity of current nuclear models is not guaranteed. A nuclear shell model is introduced to the calculation of the nuclear barrier of less deformed proton emitters. The predictions using the proposed model are in good agreement with the data, with the advantage of have used only a single parameter in the model.

  9. Decay rates of spherical and deformed proton emitters

    SciTech Connect

    Davids, C. N.; Esbensen, H.

    1999-11-23

    Using Green's function techniques, the authors derive expressions for the width of a proton decaying state in spherical and deformed nuclei. The authors show that the proton decay widths calculated by the exact expressions of Maglione et al. are equivalent to the distorted wave expressions of Bugrov et al., and that of {angstrom} berg et al. in the spherical case.

  10. Excited-state intramolecular proton-transfer (ESIPT)-inspired solid state emitters.

    PubMed

    Padalkar, Vikas S; Seki, Shu

    2016-01-07

    Solid state emitters based on excited state intramolecular proton transfer (ESIPT) have been attracting considerable interest since the past few years in the field of optoelectronic devices because of their desirable unique photophysical properties. The photophysical properties of the solid state ESIPT fluorophores determine their possible applicability in functional materials. Less fluorescence quantum efficiencies and short fluorescence lifetime in the solid state are the shortcomings of the existing ESIPT solid state emitters. Designing of ESIPT chromophores with high fluorescence quantum efficiencies and a long fluorescence lifetime in the solid state is a challenging issue because of the unclear mechanism of the solid state emitters in the excited state. Reported design strategies, detailed photophysical properties, and their applications will help in assisting researchers to overcome existing challenges in designing novel solid state ESIPT fluorophores for promising applications. This review highlights recently developed solid state ESIPT emitters with focus on molecular design strategies and their photophysical properties, reported in the last five years.

  11. Nonadiabatic effects in odd-odd deformed proton emitters

    SciTech Connect

    Patial, M.; Jain, A. K.; Arumugam, P.; Maglione, E.; Ferreira, L. S.

    2011-11-30

    We present for the first time, the nonadiabatic quasiparticle approach to study proton emission from odd-odd deformed nuclei. Coriolis effects are incorporated in both the parent and daughter wavefunctions and hence our formalism allows us to study their complete role on the decay widths. First results obtained for the nucleus {sup 112}Cs suggest a weak dependance on Coriolis effect. However, we are able to reproduce the experimental half-lives without assuming the exact Nilsson orbital from which the decay proceeds.

  12. Analysis and modeling of proton beam loss and emittance growth in the Relativistic Heavy Ion Collider

    DOE PAGES

    Luo, Y.; Fischer, W.; White, S.

    2016-02-04

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been operating since 2000. Over the past decade, thanks to the continuously increased bunch intensity and reduced β*s at the interaction points, the peak luminosity in the polarized proton operation has been increased by more than two orders of magnitude. In this article, we will present the operational observations at the routine proton physics stores. In addition, the mechanisms for the beam loss, transverse emittance growth, and bunch lengthening are analyzed. Lastly, numerical calculations and multiparticle tracking are used to model these observations.

  13. Challenges in proton radioactivity studies - new emitters in the rare earth region.

    NASA Astrophysics Data System (ADS)

    Grzywacz, Robert

    2004-10-01

    Proton emitter studies offer a sensitive probe of the wave function composition for nuclei beyond the proton drip-line. In particular, the experiments on proton radioactivities in the rare earth region are allowing us to study the evolution of proton-emitting states as a function of changing deformation, from nearly spherical (e.g.^150Lu [1] or ^145Tm [2]) to strongly deformed (e.g. ^131Eu [3], ^135Tb [4] or ^141Ho [5]) shapes. The link between the measured observables (decay lifetimes and energies) and structure of the nuclei is provided by recently developed theories, which are able to model the proton tunneling process through the three dimensional potential barrier, see refs [6-8]. Very high detection efficiency and high sensitivity enable experiments at extremely low production cross sections, e.g. at the nanobarn level for the observation of ^135Tb in a (p6n) fusion-evaporation reaction channel [4]. Recent discoveries of proton radioactive nuclei will be reported. The experimental challenges will be illustrated with the example of the identification of new odd-odd emitter ^144Tm at the Recoil Mass Spectrometer [9] of Oak Ridge National Laboratory. The ^144Tm events were found in a weak ( 10 nb) p5n channel of the fusion reaction of ^58Ni beam at 340 MeV on a ^92Mo target. The observed decay energy of about 1.8 MeV and the half-life of the order of 1 μs suggest proton emission from the πh_11/2 orbital dominating the π-ν wave function. The detection of this very short proton emitter was made possible by use of a double-sided silicon strip detector connected to a fast data acquisition system [10] based on Digital Signal Processing. [1] P.G. Sellin et al., Phys. Rev. C47, 1933 (1993). [2] M. Karny et al., Phys. Rev. Lett. 90 , 012502 (2003). [3] A.A. Sonzogni et al., Phys. Rev. Lett. 83 , 1116 (1999). [4] P.J. Woods et al., Phys. Rev. C69 , 051302(R) (2004). [5] K. Rykaczewski, K. P. et al., in Proc. of Int. Conf. on Nuclear Structure ``Mapping the Triangle

  14. Measurement and verification of positron emitter nuclei generated at each treatment site by target nuclear fragment reactions in proton therapy

    SciTech Connect

    Miyatake, Aya; Nishio, Teiji; Ogino, Takashi; Saijo, Nagahiro; Esumi, Hiroyasu; Uesaka, Mitsuru

    2010-08-15

    Purpose: The purpose of this study is to verify the characteristics of the positron emitter nuclei generated at each treatment site by proton irradiation. Methods: Proton therapy using a beam on-line PET system mounted on a rotating gantry port (BOLPs-RGp), which the authors developed, is provided at the National Cancer Center Kashiwa, Japan. BOLPs-RGp is a monitoring system that can confirm the activity distribution of the proton irradiated volume by detection of a pair of annihilation gamma rays coincidentally from positron emitter nuclei generated by the target nuclear fragment reactions between irradiated proton nuclei and nuclei in the human body. Activity is measured from a start of proton irradiation to a period of 200 s after the end of the irradiation. The characteristics of the positron emitter nuclei generated in a patient's body were verified by the measurement of the activity distribution at each treatment site using BOLPs-RGp. Results: The decay curves for measured activity were able to be approximated using two or three half-life values regardless of the treatment site. The activity of half-life value of about 2 min was important for a confirmation of the proton irradiated volume. Conclusions: In each proton treatment site, verification of the characteristics of the generated positron emitter nuclei was performed by using BOLPs-RGp. For the monitoring of the proton irradiated volume, the detection of {sup 15}O generated in a human body was important.

  15. Studies and calculations of transverse emittance growth in high-energy proton storage rings

    SciTech Connect

    Mane, S.R.; Jackson, G.

    1989-03-01

    In the operation of proton-antiproton colliders, an important goal is to maximize the integrated luminosity. During such operations in the Fermilab Tevatron, the transverse beam emittances were observed to grow unexpectedly quickly, thus causing a serious reduction of the luminosity. We have studied this phenomenon experimentally and theoretically. A formula for the emittance growth rate, due to random dipole kicks, is derived. In the experiment, RF phase noise of known amplitude was deliberately injected into the Tevatron to kick the beam randomly, via dispersion at the RF cavities. Theory and experiment are found to agree reasonably well. We also briefly discuss the problem of quadrupole kicks. 14 refs., 2 figs., 3 tabs.

  16. Booster and AGS transverse emittance during the 2006 and 2009 polarized proton runs

    SciTech Connect

    Zeno, K.

    2010-09-01

    This note is an overview of issues relating to transverse polarized proton emittance in the Booster and AGS. It also compares the transverse emittance during the FY09 polarized proton run with it during the FY06 run as several changes were made for the FY09 run in an attempt to reduce the transverse emittance coming out of the AGS. The FY06 run is used for comparison because it was relatively long, and it's believed that the performance of the injectors for polarized protons, up until FY09, was best during that run. Over the shutdown just before the FY09 run work was done in LEBT and MEBT to reduce the emittance coming out of the Linac. Measurements of the beam coming out of Linac1 indicate that the horizontal normalized emittance was reduced from 11.0 {pi} to 4.5 {pi}mm mrad, and that the vertical normalized emittance was reduced from 12.1 {pi} to 5.5 {pi} mm mrad going from FY06 to FY09. There were 2 new types of stripping foil installed in the Booster, called descriptively the 'strip' (No.6) and 'stamp' (No.2) foil, both nominally 100 {micro}g/cm{sup 2}. Both foils are composed of a diamond like material, and designed to reduce the number of times the beam goes through the foil. Other than those, there are two standard 100 {micro}g/cm carbon foils (No.3 and 5), and one 200 {micro}g/cm{sup 2} carbon foil (No.4). Of the two 100 {micro}g/cm{sup 2} foils, one has shown some deterioration (No.3) in stripping efficiency. During the FY06 run a standard 100 {micro}g/cm{sup 2} foil was generally used, and during the FY09 run the strip foil was generally used, though the stamp foil was also used for the last 3-4 weeks of the run. Both the FY06 and FY09 runs were about 5 months long, starting in late January, FY06 ending in late June, and FY09 ending in early July. A new injection setup was used for about the last 3 months of FY09, from the beginning of April to the end of the run. This setup uses 1/2 integer stopband correctors with the tunes near, but slightly greater

  17. Note: Emittance measurements of intense pulsed proton beam for different pulse length and repetition rate

    SciTech Connect

    Miracoli, R.; Gammino, S.; Celona, L.; Mascali, D.; Castro, G.; Gobin, R.; Delferriere, O.; Adroit, G.; Senee, F.; Ciavola, G.

    2012-05-15

    The high intensity ion source (SILHI), in operation at CEA-Saclay, has been used to produce a 90 mA pulsed proton beam with pulse length and repetition rates suitable for the European Spallation Source (ESS) linac. Typical r-r{sup '} rms normalized emittance values smaller than 0.2{pi} mm mrad have been measured for operation in pulsed mode (0.01 < duty cycle < 0.15 and 1 ms < pulse duration < 10 ms) that are relevant for the design update of the Linac to be used at the ESS in Lund.

  18. Half-lives of spherical proton emitters within the framework of fractional calculus

    NASA Astrophysics Data System (ADS)

    Çalik, Abdullah Engin; Şirin, Hüseyin; Ertik, Hüseyin; Öder, Buket; Şen, Mürsel

    2014-08-01

    In this paper, the half-life values of spherical proton emitters such as Sb, Tm, Lu, Ta, Re, Ir, Au, Tl and Bi have been calculated within the framework of fractional calculus. Nuclear decay equation, related to this phenomenon, has been resolved by using Caputo fractional derivative. The order of fractional derivative μ being considered is 0 < μ ≤ 1, and characterizes the fractality of time. Half-life values have been calculated equivalent with empirical ones. The dependence of fractional derivative order μ on the nuclear structure has also been investigated.

  19. New Isotopes and Proton Emitters-Crossing the Drip Line in the Vicinity of ^{100}Sn.

    PubMed

    Čeliković, I; Lewitowicz, M; Gernhäuser, R; Krücken, R; Nishimura, S; Sakurai, H; Ahn, D S; Baba, H; Blank, B; Blazhev, A; Boutachkov, P; Browne, F; de France, G; Doornenbal, P; Faestermann, T; Fang, Y; Fukuda, N; Giovinazzo, J; Goel, N; Górska, M; Ilieva, S; Inabe, N; Isobe, T; Jungclaus, A; Kameda, D; Kim, Y-K; Kwon, Y K; Kojouharov, I; Kubo, T; Kurz, N; Lorusso, G; Lubos, D; Moschner, K; Murai, D; Nishizuka, I; Park, J; Patel, Z; Rajabali, M; Rice, S; Schaffner, H; Shimizu, Y; Sinclair, L; Söderström, P-A; Steiger, K; Sumikama, T; Suzuki, H; Takeda, H; Wang, Z; Watanabe, H; Wu, J; Xu, Z

    2016-04-22

    Several new isotopes, ^{96}In, ^{94}Cd, ^{92}Ag, and ^{90}Pd, have been identified at the RIKEN Nishina Center. The study of proton drip-line nuclei in the vicinity of ^{100}Sn led to the discovery of new proton emitters ^{93}Ag and ^{89}Rh with half-lives in the submicrosecond range. The systematics of the half-lives of odd-Z nuclei with T_{z}=-1/2 toward ^{99}Sn shows a stabilizing effect of the Z=50 shell closure. Production cross sections for nuclei in the vicinity of ^{100}Sn measured at different energies and target thicknesses were compared to the cross sections calculated by epax taking into account contributions of secondary reactions in the primary target.

  20. Search for {beta}-delayed fission of {sup 228}Ac

    SciTech Connect

    Xu Yanbing; Ding Huajie; Yuan Shuanggui; Yang Weifan; Niu Yanning; Li Yingjun; Xiao Yonghou; Zhang Shengdong; Lu Xiting

    2006-10-15

    Radium was radiochemically separated from natural thorium. Thin {sup 228}Ra{yields}{beta}{sup -228}Ac sources were prepared and exposed to mica fission track detectors, and measured by an HPGe {gamma}-ray detector. The {beta}-delayed fission events of {sup 228}Ac were observed and its {beta}-delayed fission probability was found to be (5{+-}2)x10{sup -12}.

  1. Quantification of radiation dose from short-lived positron emitters formed in human tissue under proton therapy conditions

    NASA Astrophysics Data System (ADS)

    Kettern, K.; Coenen, H. H.; Qaim, S. M.

    2009-06-01

    The dose distribution in proton therapy is mainly due to primary particles and secondary electrons. The contribution of short-lived β + emitters formed in the interactions of protons with the light mass elements C, N and O has hitherto not been considered. We estimated the formation of 11C, 13N and 15O in irradiation of tissue with 200 MeV protons. The integral yields at 150 MeV were compared with a literature phantom measurement. The results for 11C and 15O agreed very well; for 13N, however, appreciable deviation was observed. The activities were also calculated in the region around the Bragg peak as well as over the path length after entrance of the beam. Dose calculations were then done using the medical internal radiation dose (MIRD) formalism. Furthermore, a dose calculation was simulated for a 150 MeV proton beam (2 nA, 2 min) in a brain tumour. The dose deposited by the positron emitters in the Bragg peak region was found to be about 1.5 mGy, i.e. less than 1% of the dose estimated from the electronic interactions of protons. The absorbed dose in the whole brain amounted to 5.5 mGy.

  2. Short-lived positron emitters in beam-on PET imaging during proton therapy.

    PubMed

    Dendooven, P; Buitenhuis, H J T; Diblen, F; Heeres, P N; Biegun, A K; Fiedler, F; van Goethem, M-J; van der Graaf, E R; Brandenburg, S

    2015-12-07

    The only method for in vivo dose delivery verification in proton beam radiotherapy in clinical use today is positron emission tomography (PET) of the positron emitters produced in the patient during irradiation. PET imaging while the beam is on (so called beam-on PET) is an attractive option, providing the largest number of counts, the least biological washout and the fastest feedback. In this implementation, all nuclides, independent of their half-life, will contribute. As a first step towards assessing the relevance of short-lived nuclides (half-life shorter than that of (10)C, T1/2  =  19 s) for in vivo dose delivery verification using beam-on PET, we measured their production in the stopping of 55 MeV protons in water, carbon, phosphorus and calcium The most copiously produced short-lived nuclides and their production rates relative to the relevant long-lived nuclides are: (12)N (T1/2  =  11 ms) on carbon (9% of (11)C), (29)P (T1/2  =  4.1 s) on phosphorus (20% of (30)P) and (38m)K (T1/2  =  0.92 s) on calcium (113% of (38g)K). No short-lived nuclides are produced on oxygen. The number of decays integrated from the start of an irradiation as a function of time during the irradiation of PMMA and 4 tissue materials has been determined. For (carbon-rich) adipose tissue, (12)N dominates up to 70 s. On bone tissue, (12)N dominates over (15)O during the first 8-15 s (depending on carbon-to-oxygen ratio). The short-lived nuclides created on phosphorus and calcium provide 2.5 times more beam-on PET counts than the long-lived ones produced on these elements during a 70 s irradiation. From the estimated number of (12)N PET counts, we conclude that, for any tissue, (12)N PET imaging potentially provides equal to superior proton range information compared to prompt gamma imaging with an optimized knife-edge slit camera. The practical implementation of (12)N PET imaging is discussed.

  3. Short-lived positron emitters in beam-on PET imaging during proton therapy

    NASA Astrophysics Data System (ADS)

    Dendooven, P.; Buitenhuis, H. J. T.; Diblen, F.; Heeres, P. N.; Biegun, A. K.; Fiedler, F.; van Goethem, M.-J.; van der Graaf, E. R.; Brandenburg, S.

    2015-12-01

    The only method for in vivo dose delivery verification in proton beam radiotherapy in clinical use today is positron emission tomography (PET) of the positron emitters produced in the patient during irradiation. PET imaging while the beam is on (so called beam-on PET) is an attractive option, providing the largest number of counts, the least biological washout and the fastest feedback. In this implementation, all nuclides, independent of their half-life, will contribute. As a first step towards assessing the relevance of short-lived nuclides (half-life shorter than that of 10C, T1/2  =  19 s) for in vivo dose delivery verification using beam-on PET, we measured their production in the stopping of 55 MeV protons in water, carbon, phosphorus and calcium The most copiously produced short-lived nuclides and their production rates relative to the relevant long-lived nuclides are: 12N (T1/2  =  11 ms) on carbon (9% of 11C), 29P (T1/2  =  4.1 s) on phosphorus (20% of 30P) and 38mK (T1/2  =  0.92 s) on calcium (113% of 38gK). No short-lived nuclides are produced on oxygen. The number of decays integrated from the start of an irradiation as a function of time during the irradiation of PMMA and 4 tissue materials has been determined. For (carbon-rich) adipose tissue, 12N dominates up to 70 s. On bone tissue, 12N dominates over 15O during the first 8-15 s (depending on carbon-to-oxygen ratio). The short-lived nuclides created on phosphorus and calcium provide 2.5 times more beam-on PET counts than the long-lived ones produced on these elements during a 70 s irradiation. From the estimated number of 12N PET counts, we conclude that, for any tissue, 12N PET imaging potentially provides equal to superior proton range information compared to prompt gamma imaging with an optimized knife-edge slit camera. The practical implementation of 12N PET imaging is discussed.

  4. Beta-delayed neutron spectroscopy using ion traps

    NASA Astrophysics Data System (ADS)

    Wang, Barbara; Czeszumska, A.; Siegl, K.; Caldwell, S.; Aprahamian, A.; Burkey, M.; Clark, J.; Levand, A.; Marley, S.; Morgan, G.; Norman, E.; Nystrom, A.; Orford, R.; Padgett, S.; Perez Galvan, A.; Savard, G.; Scielzo, N.; Sharma, K.; Strauss, S.

    2016-09-01

    Trapped radioactive ions suspended in vacuum allow for a new way to perform beta-delayed neutron spectroscopy. Decay branching ratios and energy spectra of the emitted neutrons are inferred from a measurement of the nuclear recoil, thereby circumventing the many limitations associated with direct neutron detection. Beta-delayed neutron measurements were carried out for 137 - 138 , 140I, 134-136Sb, and 144-145Cs at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The data collected are needed in many fields of basic and applied science such as nuclear energy, nuclear astrophysics, and stockpile stewardship. Results for the isotopes 135-136Sb and 140I will be presented. Supported by NSF under PHY-1419765, U.S. DOE under NEUP 13-5485, DE-AC02-06CH11357 (ANL), DE-AC52-07NA27344 (LLNL), and DE-NA0000979 (NNSA).

  5. Beta-delayed neutron spectroscopy using ion traps

    NASA Astrophysics Data System (ADS)

    Wang, Barbara; Czeszumska, A.; Siegl, K.; Caldwell, S.; Aprahamian, A.; Burkey, M.; Clark, J.; Levand, A.; Marley, S.; Morgan, G.; Norman, E.; Nystrom, A.; Orford, R.; Padgett, S.; Perez Galvan, A.; Savard, G.; Scielzo, N.; Sharma, K.; Strauss, S.

    2017-01-01

    Trapped radioactive ions suspended in vacuum allow for a new way to perform beta-delayed neutron spectroscopy. Decay branching ratios and energy spectra of the emitted neutrons are inferred from a measurement of the nuclear recoil, thereby circumventing the many limitations associated with direct neutron detection. Beta-delayed neutron measurements were carried out for 137-138,140I, 134-136Sb, and 144-145Cs at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The data collected are needed in many fields of basic and applied science such as nuclear energy, nuclear astrophysics, and stockpile stewardship. Results for the isotopes 135-136Sb and 140I will be presented. Supported by NSF under PHY-1419765, and U.S. DOE under NEUP 13-5485, DE-AC02-06CH11357 (ANL), DE-AC52-07NA27344 (LLNL), and DE-NA0000979 (NNSA).

  6. Clinical CT-based calculations of dose and positron emitter distributions in proton therapy using the FLUKA Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Parodi, K.; Ferrari, A.; Sommerer, F.; Paganetti, H.

    2007-07-01

    Clinical investigations on post-irradiation PET/CT (positron emission tomography/computed tomography) imaging for in vivo verification of treatment delivery and, in particular, beam range in proton therapy are underway at Massachusetts General Hospital (MGH). Within this project, we have developed a Monte Carlo framework for CT-based calculation of dose and irradiation-induced positron emitter distributions. Initial proton beam information is provided by a separate Geant4 Monte Carlo simulation modelling the treatment head. Particle transport in the patient is performed in the CT voxel geometry using the FLUKA Monte Carlo code. The implementation uses a discrete number of different tissue types with composition and mean density deduced from the CT scan. Scaling factors are introduced to account for the continuous Hounsfield unit dependence of the mass density and of the relative stopping power ratio to water used by the treatment planning system (XiO (Computerized Medical Systems Inc.)). Resulting Monte Carlo dose distributions are generally found in good correspondence with calculations of the treatment planning program, except a few cases (e.g. in the presence of air/tissue interfaces). Whereas dose is computed using standard FLUKA utilities, positron emitter distributions are calculated by internally combining proton fluence with experimental and evaluated cross-sections yielding 11C, 15O, 14O, 13N, 38K and 30P. Simulated positron emitter distributions yield PET images in good agreement with measurements. In this paper, we describe in detail the specific implementation of the FLUKA calculation framework, which may be easily adapted to handle arbitrary phase spaces of proton beams delivered by other facilities or include more reaction channels based on additional cross-section data. Further, we demonstrate the effects of different acquisition time regimes (e.g., PET imaging during or after irradiation) on the intensity and spatial distribution of the irradiation

  7. Future laser-accelerated proton beams at ELI-Beamlines as potential source of positron emitters for PET

    NASA Astrophysics Data System (ADS)

    Amato, E.; Italiano, A.; Margarone, D.; Pagano, B.; Baldari, S.; Korn, G.

    2016-04-01

    The development of novel compact PET radionuclide production systems is of great interest to promote the diffusion of PET diagnostics, especially in view of the continuous development of novel, fast and efficient, radiopharmaceutical methods of labeling. We studied the feasibility to produce clinically-relevant amounts of PET isotopes by means of laser-accelerated proton sources expected at the ELI-Beamlines facility where a PW, 30 fs, 10 Hz laser system will be available. The production yields of several positron emitters were calculated through the TALYS software, by taking into account three possible scenarios of broad proton spectra expected, with maximum energies ranging from about 8 MeV to 100 MeV. With the hypothesized proton fluencies, clinically-relevant amounts of radionuclides can be obtained, suitable to prepare single doses of radiopharmaceuticals exploiting modern fast and efficient labeling systems.

  8. SU-C-204-07: The Production of Short-Lived Positron Emitters in Proton Therapy

    SciTech Connect

    Buitenhuis, H J T; Dendooven, P; Biegun, A K; Goethem, M-J van; Graaf, E R van der; Brandenburg, S; Diblen, F

    2015-06-15

    Purpose: To investigate the production and effect of short-lived positron emitters when using PET for in-vivo range verification during a proton therapy irradiation. Methods: The integrated production of short-lived positron emitters in the stopping of 55 MeV protons was measured in water, carbon, phosphorus and calcium targets. The experimental production rates are used to calculate the production on PMMA and a representative set of 4 tissue materials. The number of decays integrated over an irradiation in these materials is calculated as function of the duration of the irradiation, considering irradiations with the same total number of protons. Results: The most copiously produced short-lived nuclides and their production rates relative to the relevant long-lived nuclides are: 12-N (T1/2 = 11 ms) on carbon (9.5% of the 11-C production), 29-P (T1/2 = 4.1 s) on phosphorus (20% of the 30-P production) and 38m-K (T1/2 = 0.92 s) on calcium (113% of the 38g-K production). No short-lived nuclides are produced on water. The most noticeable Result is that for an irradiation in (carbon-rich) adipose tissue, 12-N will dominate the PET image up to an irradiation duration of 70 s. On bone tissue, 15-O dominates over 12-N after 7–15 s (depending on the carbon-to-oxygen ratio). Conclusions: The presence of 12-N needs to be considered in PET imaging during proton beam irradiations as, depending on tissue composition and PET scanning protocol, it may noticeably deteriorate image quality due to the large positron range blurring. The results presented warrant investigations into the energy-dependent production of 12-N, 29-P and 38m-K and their effect on PET imaging during proton irradiations.

  9. Spectroscopic factor and proton formation probability for the d3/2 proton emitter 151mLu

    NASA Astrophysics Data System (ADS)

    Wang, F.; Sun, B. H.; Liu, Z.; Page, R. D.; Qi, C.; Scholey, C.; Ashley, S. F.; Bianco, L.; Cullen, I. J.; Darby, I. G.; Eeckhaudt, S.; Garnsworthy, A. B.; Gelletly, W.; Gomez-Hornillos, M. B.; Grahn, T.; Greenlees, P. T.; Jenkins, D. G.; Jones, G. A.; Jones, P.; Joss, D. T.; Julin, R.; Juutinen, S.; Ketelhut, S.; Khan, S.; Kishada, A.; Leino, M.; Niikura, M.; Nyman, M.; Pakarinen, J.; Pietri, S.; Podolyak, Z.; Rahkila, P.; Rigby, S.; Saren, J.; Shizuma, T.; Sorri, J.; Steer, S.; Thomson, J.; Thompson, N. J.; Uusitalo, J.; Walker, P. M.; Williams, S.; Zhang, H. F.; Zhang, W. Q.; Zhu, L. H.

    2017-07-01

    The quenching of the experimental spectroscopic factor for proton emission from the short-lived d3/2 isomeric state in 151mLu was a long-standing problem. In the present work, proton emission from this isomer has been reinvestigated in an experiment at the Accelerator Laboratory of the University of Jyväskylä. The proton-decay energy and half-life of this isomer were measured to be 1295(5) keV and 15.4(8) μs, respectively, in agreement with another recent study. These new experimental data can resolve the discrepancy in the spectroscopic factor calculated using the spherical WKB approximation. Using the R-matrix approach it is found that the proton formation probability indicates no significant hindrance for the proton decay of 151mLu.

  10. Beta-Delayed Neutron Spectroscopy Using VANDLE at CARIBU

    NASA Astrophysics Data System (ADS)

    Taylor, S.; Kolos, K.; Grzywacz, R.; Paulauskas, S. V.; Madurga, M.; Savard, G.; Brewer, N. T.; Vandle Collaboration

    2015-10-01

    Measurement of spectroscopic information on beta-delayed neutrons of neutron rich fission fragments is of interest to the areas of astrophysics, reactor design, nuclear structure and stockpile stewardship. Using the Time of Flight (TOF) method, the Versatile Array of Neutron Detectors at Low Energy(VANDLE)[1,2,3] measured fission fragments of 252Cf provided by CARIBU at Argonne National Lab. 135,136Sb and 85As isotopes were measured to explore the nuclear structure around doubly magic nuclei 132Sn and 78Ni. A new TOF start detector was developed for this experiment using new Silicon Photo-Multipliers from SensL to allow for a lower beta particle energy detection threshold and better timing resolution compared to previous VANDLE experiments. This work is funded by the U.S. Department of Energy NNSA under the Stewardship Science Academic Alliance program through DOE Cooperative Agreement No. DE-FG52-08NA28552.

  11. Recoil Decay Tagging Study Of Transitional Proton Emitters 145,146,147Tm

    SciTech Connect

    Robinson, A.P.; Woods, P.J.; Davinson, T.; Liu, Z.; Davids, C.N.; Seweryniak, D.; Carpenter, M.P.; Hammond, N.; Janssens, R.V.F.; Mukherjee, G.; Sinha, S.; Blank, B.; Freeman, S.J.; Hoteling, N.; Shergur, J.; Walters, W.B.; Scholey, C.; Sonzogni, A.A.; Woehr, A.

    2005-04-05

    Gamma rays from the transitional proton emitting nuclei 145,146,147Tm have been observed using the recoil-decay tagging technique. The ground state band of 147Tm was confirmed and extended and the unfavoured signature sequence was observed. A ground state rotational band with properties of a decoupled h11/2 band was observed in 145Tm. In addition coincidences between the proton fine structure line and the 2+{yields}0+ {gamma}-ray transition in 144Er were detected at the focal plane of the FMA. This is the first time that coincidences between proton radioactive decays and {gamma} rays have been seen. The particle decay of 146Tm has been measured with improved statistics and a rotational band similar to 147Tm has been observed.

  12. Emittance improvement of the electron cyclotron resonance high intensity light ion source proton beam by gas injection in the low energy beam transport

    NASA Astrophysics Data System (ADS)

    Beauvais, P.-Y.; Ferdinand, R.; Gobin, R.; Lagniel, J. M.; Leroy, P.-A.; Celona, L.; Ciavola, G.; Gammino, S.; Pottin, B.; Sherman, J.

    2000-03-01

    SILHI is the ECR high intensity light ion source studied in France at C.E.A. Saclay. This is the source for the injector of the high intensity proton injector prototype developed by a CNRS-IN2P3 collaboration. 80 mA at 95 keV beams with a rms normalized r-r' emittance lower than 0.3 π mm mrad and a proton fraction better than 85% are currently produced. Recently, it has been found that the injection in the low energy beam transport of a buffer gas had a strong effect on the emittance measured 1 m downstream of the focusing solenoid. By adding several gases (H2, N2, Ar, Kr), improvements as great as a factor of 3 have been observed. The emittance has been measured by means of an r-r' emittance measurement unit equipped with a sampling hole and a wire profile monitor, both moving across the beam. Simultaneously, the space charge compensation factor is measured using a four-grid analyzer unit. In this article all results of these experiments are presented and discussed. A first explanation of the emittance reduction phenomenon and possible consequences on the injector operation is given.

  13. Beam-on imaging of short-lived positron emitters during proton therapy

    NASA Astrophysics Data System (ADS)

    Buitenhuis, H. J. T.; Diblen, F.; Brzezinski, K. W.; Brandenburg, S.; Dendooven, P.

    2017-06-01

    In vivo dose delivery verification in proton therapy can be performed by positron emission tomography (PET) of the positron-emitting nuclei produced by the proton beam in the patient. A PET scanner installed in the treatment position of a proton therapy facility that takes data with the beam on will see very short-lived nuclides as well as longer-lived nuclides. The most important short-lived nuclide for proton therapy is 12N (Dendooven et al 2015 Phys. Med. Biol. 60 8923-47), which has a half-life of 11 ms. The results of a proof-of-principle experiment of beam-on PET imaging of short-lived 12N nuclei are presented. The Philips Digital Photon Counting Module TEK PET system was used, which is based on LYSO scintillators mounted on digital SiPM photosensors. A 90 MeV proton beam from the cyclotron at KVI-CART was used to investigate the energy and time spectra of PET coincidences during beam-on. Events coinciding with proton bunches, such as prompt gamma rays, were removed from the data via an anti-coincidence filter with the cyclotron RF. The resulting energy spectrum allowed good identification of the 511 keV PET counts during beam-on. A method was developed to subtract the long-lived background from the 12N image by introducing a beam-off period into the cyclotron beam time structure. We measured 2D images and 1D profiles of the 12N distribution. A range shift of 5 mm was measured as 6  ±  3 mm using the 12N profile. A larger, more efficient, PET system with a higher data throughput capability will allow beam-on 12N PET imaging of single spots in the distal layer of an irradiation with an increased signal-to-background ratio and thus better accuracy. A simulation shows that a large dual panel scanner, which images a single spot directly after it is delivered, can measure a 5 mm range shift with millimeter accuracy: 5.5  ±  1.1 mm for 1  ×  108 protons and 5.2  ±  0.5 mm for 5  ×  108 protons. This makes

  14. Studies of Beta-Delayed Neutron Emission using Trapped Ions

    NASA Astrophysics Data System (ADS)

    Siegl, Kevin; Aprahamian, A.; Scielzo, N. D.; Savard, G.; Clark, J. A.; Levand, A. F.; Burkey, M.; Caldwell, S.; Czeszumska, A.; Hirsh, T. Y.; Kolos, K.; Marley, S. T.; Morgan, G. E.; Norman, E. B.; Nystrom, A.; Orford, R.; Padgett, S.; Pérez Galván, A.; Sh, K. S.; Strauss, S. Y.; Wang, B. S.

    2017-01-01

    Using a radio-frequency quadrupole ion trap to confine radioactive ions allows indirect measurements of beta-delayed neutron (BDN) emission. By determining the recoil energy of the beta-decay daughter ions it is possible to study BDN emission, as the neutron emission can impart a significantly larger nuclear recoil than from beta-decay alone. This method avoids most of the systematic uncertainties associated with direct neutron detection but introduces dependencies on the specifics of the decay and interactions of the ion with the RF fields. The decays of seven BDN precursors were studied using the Beta-decay Paul Trap (BPT) to confine fission fragments from the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory. The analysis of these measurements and results for the branching ratios and neutron energy spectra will be presented. Supported by the NSF under grant PHY-1419765, and the U.S. DOE under the NEUP project 13-5485, contracts DE-AC02-06CH11357 (ANL) and DE-AC52-07NA27344 (LLNL), and award DE-NA0000979 (NNSA).

  15. Application of activity pencil beam algorithm using measured distribution data of positron emitter nuclei for therapeutic SOBP proton beam

    SciTech Connect

    Miyatake, Aya; Nishio, Teiji

    2013-09-15

    Purpose: Recently, much research on imaging the clinical proton-irradiated volume using positron emitter nuclei based on target nuclear fragment reaction has been carried out. The purpose of this study is to develop an activity pencil beam (APB) algorithm for a simulation system for proton-activated positron-emitting imaging in clinical proton therapy using spread-out Bragg peak (SOBP) beams.Methods: The target nuclei of activity distribution calculations are {sup 12}C nuclei, {sup 16}O nuclei, and {sup 40}Ca nuclei, which are the main elements in a human body. Depth activity distributions with SOBP beam irradiations were obtained from the material information of ridge filter (RF) and depth activity distributions of compounds of the three target nuclei measured by BOLPs-RGp (beam ON-LINE PET system mounted on a rotating gantry port) with mono-energetic Bragg peak (MONO) beam irradiations. The calculated data of depth activity distributions with SOBP beam irradiations were sorted in terms of kind of nucleus, energy of proton beam, SOBP width, and thickness of fine degrader (FD), which were verified. The calculated depth activity distributions with SOBP beam irradiations were compared with the measured ones. APB kernels were made from the calculated depth activity distributions with SOBP beam irradiations to construct a simulation system using the APB algorithm for SOBP beams.Results: The depth activity distributions were prepared using the material information of RF and the measured depth activity distributions with MONO beam irradiations for clinical therapy using SOBP beams. With the SOBP width widening, the distal fall-offs of depth activity distributions and the difference from the depth dose distributions were large. The shapes of the calculated depth activity distributions nearly agreed with those of the measured ones upon comparison between the two. The APB kernels of SOBP beams were prepared by making use of the data on depth activity distributions with SOBP

  16. Beta delayed neutrons for nuclear structure and astrophysics

    NASA Astrophysics Data System (ADS)

    Grzywacz, Robert

    2014-09-01

    Beta-delayed neutron emission (β xn) is a significant or even dominant decay channel for the majority of very neutron-rich nuclei, especially for those on the r-process path. The recent theoretical models predicts that it may play more significant role then previously expected for astrophysics and this realization instigated a renewed experimental interest in this topic as a part of a larger scope of research on beta-decay strength distribution. Because studies of the decay strength directly probe relevant physics on the microscopic level, energy-resolved measurements of the beta-decay strength distribution is a better test of nuclear models than traditionally used experimental observables like half-lives and neutron branching ratios. A new detector system called the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was constructed to directly address this issue. In its first experimental campaign at the Holifield Radioactive Ion Beam Facility neutron energy spectra in key regions of the nuclear chart were measured: near the shell closures at 78Ni and 132Sn, and for the deformed nuclei near 100Rb. In several cases, unexpectedly intense and concentrated, resonant-like, high-energy neutron structures were observed. These results were interpreted within shell model framework which clearly indicated that these neutron emission is driven by nuclear structure effects and are due to large Gamow-Teller type transition matrix elements. This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552.

  17. Beta-delayed fission probabilities of transfermium nuclei, involved in the r-process

    NASA Astrophysics Data System (ADS)

    Panov, I.; Lutostansky, Yu; Thielemann, F.-K.

    2016-01-01

    For the nucleosynthesis of heavy and superheavy nuclei fission becomes very important when the r-process runs in a very high neutron density environment. In part, fission is responsible for the formation of heavy nuclei due to the inclusion of fission products as new seed nuclei (fission cycling). More than that, beta-delayed fission, along with spontaneous fission, is responsible in the late stages of the r-process for the suppression of superheavy element yields. For beta-delayed fission probability calculations a model description of the beta-strength- functions is required. Extended theoretical predictions for astro-physical applications were provided long ago, and new predictions also for superheavy nuclei with uptodate nuclear input are needed. For the further extension of data to heavier transactinides the models of strength- functions should be modified, taking into account more complicated level schemes. In our present calculations the strength-function model is based on the quasi-particle approximation of Finite Fermi Systems Theory. The probabilities of beta-delayed fission and beta-delayed neutron emission are calculated for some transfermium neutron-rich nuclei, and the influence of beta-delayed fission upon superheavy element formation is discussed.

  18. A trapped-ion technique for beta-delayed neutron studies

    NASA Astrophysics Data System (ADS)

    Caldwell, Shane

    The properties of beta-delayed neutron emission (betan) are important in basic and applied nuclear physics. The neutron spectra and branching ratios of betan emitters reflect the evolution of nuclear structure in neutron-rich nuclei. Branching ratios affect the heavy-element abundances resulting from the astrophysical r process. Energy spectra and branching ratios are also important to nuclear stockpile stewardship and the safe design of nuclear reactors. Recently we demonstrated a novel technique for betan spectroscopy using I137+ ions confined to a ˜1 mm 3 volume within a linear RFQ ion trap [61, 77]. By measuring the time-of-flight spectrum of ions recoiling from both beta and betan decays, the betan branching ratio and spectrum can be determined. This recoil-ion technique has several advantages over techniques that rely on neutron detection: the recoil-ions are easily detectable; complications due to scattered neutrons and gamma-rays are avoided; and the betan branching ratio can be extracted in several ways. In this thesis we present new measurements of the delayed-neutron energy spectra and branching ratios of 137I, 135Sb, and 136Sb, which include the first observation of the 136Sb spectrum. These measurements were motivated by the impact that the branching ratios of 135Sb and136Sb can have on the r-process abundances and by the use of 137 I, a well-studied case, as a benchmark for the new technique. Our current understanding of the r process is severely limited by the lack of an exhaustive body of data on neutron-rich nuclei. Relative to the previous demonstration on 137I, the present iteration of the experiment incorporates a 10x improvement in both the detection efficiencies and the beam intensity, as well as a position-sensitive design for the recoil-ion detectors that enables an improvement in energy resolution. An important analytical tool is introduced, which models the evolution of each ion population in the trap and is used to provide a needed

  19. An experimental approach to improve the Monte Carlo modelling of offline PET/CT-imaging of positron emitters induced by scanned proton beams

    NASA Astrophysics Data System (ADS)

    Bauer, J.; Unholtz, D.; Kurz, C.; Parodi, K.

    2013-08-01

    We report on the experimental campaign carried out at the Heidelberg Ion-Beam Therapy Center (HIT) to optimize the Monte Carlo (MC) modelling of proton-induced positron-emitter production. The presented experimental strategy constitutes a pragmatic inverse approach to overcome the known uncertainties in the modelling of positron-emitter production due to the lack of reliable cross-section data for the relevant therapeutic energy range. This work is motivated by the clinical implementation of offline PET/CT-based treatment verification at our facility. Here, the irradiation induced tissue activation in the patient is monitored shortly after the treatment delivery by means of a commercial PET/CT scanner and compared to a MC simulated activity expectation, derived under the assumption of a correct treatment delivery. At HIT, the MC particle transport and interaction code FLUKA is used for the simulation of the expected positron-emitter yield. For this particular application, the code is coupled to externally provided cross-section data of several proton-induced reactions. Studying experimentally the positron-emitting radionuclide yield in homogeneous phantoms provides access to the fundamental production channels. Therefore, five different materials have been irradiated by monoenergetic proton pencil beams at various energies and the induced β+ activity subsequently acquired with a commercial full-ring PET/CT scanner. With the analysis of dynamically reconstructed PET images, we are able to determine separately the spatial distribution of different radionuclide concentrations at the starting time of the PET scan. The laterally integrated radionuclide yields in depth are used to tune the input cross-section data such that the impact of both the physical production and the imaging process on the various positron-emitter yields is reproduced. The resulting cross-section data sets allow to model the absolute level of measured β+ activity induced in the investigated

  20. Distinguishing fissions of 232Th, 237Np and 238U with beta-delayed gamma rays

    NASA Astrophysics Data System (ADS)

    Iyengar, A.; Norman, E. B.; Howard, C.; Angell, C.; Kaplan, A.; Ressler, J. J.; Chodash, P.; Swanberg, E.; Czeszumska, A.; Wang, B.; Yee, R.; Shugart, H. A.

    2013-06-01

    Measurements of beta-delayed gamma-ray spectra following 14-MeV neutron-induced fissions of 232Th, 238U, and 237Np were conducted at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. Spectra were collected for times ranging from 1 min to 14 h after irradiation. Intensity ratios of gamma-ray lines were extracted from the data that allow identification of the fissioning isotope.

  1. New Beta-delayed Neutron Measurements in the Light-mass Fission Group

    SciTech Connect

    Agramunt, J.; García, A.R.; Algora, A.; Äystö, J.; Caballero-Folch, R.; Calviño, F.; Cano-Ott, D.; Cortés, G.; Domingo-Pardo, C.; Eronen, T.; Gelletly, W.; Gómez-Hornillos, M.B.; and others

    2014-06-15

    A new accurate determination of beta-delayed neutron emission probabilities from nuclei in the low mass region of the light fission group has been performed. The measurements were carried out using the BELEN 4π neutron counter at the IGISOL-JYFL mass separator in combination with a Penning trap. The new results significantly improve the uncertainties of neutron emission probabilities for {sup 91}Br, {sup 86}As, {sup 85}As, and {sup 85}Ge nuclei.

  2. Further measurement of the {beta}-delayed {alpha}-particle emission of {sup 16}N

    SciTech Connect

    France III, R. H.; Wilds, E. L.; McDonald, J. E.; Gai, M.

    2007-06-15

    We measured the {beta}-delayed {alpha}-particle emission spectrum of {sup 16}N with a sensitivity for {beta}-decay branching ratios of the order of 10{sup -10}. The {sup 16}N nuclei were produced using the d({sup 15}N,{sup 16}N)p reaction with 70 MeV {sup 15}N beams and a deuterium gas target 7.5 cm long at a pressure of 1250 torr. The {sup 16}N nuclei were collected (over 10 s) using a thin aluminum foil with an areal density of 180 {mu}g/cm{sup 2} tilted at 7 deg. with respect to the beam. The activity was transferred to the counting area by means of a stepping motor in less than 3 s with the counting carried out over 8 s. The {beta}-delayed {alpha}-particles were measured using a time-of-flight method to achieve a sufficiently low background. Standard calibration sources ({sup 148}Gd, {sup 241}Am, {sup 208,209}Po, and {sup 227}Ac) as well as {alpha} particles and {sup 7}Li from the {sup 10}B(n,{alpha}){sup 7}Li reaction were used for an accurate energy calibration. The energy resolution of the catcher foil (180-220 keV) was calculated and the time-of-flight resolution (3-10 nsec) was measured using the {beta}-delayed {alpha}-particle emission from {sup 8}Li that was produced using the d({sup 7}Li,{sup 8}Li)p reaction with the same setup. The line shape was corrected to account for the variation in the energy and time resolution and a high statistics spectrum of the {beta}-delayed {alpha}-particle emission of {sup 16}N is reported. However, our data (as well as earlier Mainz data and unpublished Seattle data) do not agree with an earlier measurement of the {beta}-delayed {alpha}-particle emission of {sup 16}N taken at TRIUMF after averaging over the energy resolution of our collection system. This disagreement, among other issues, prohibits accurate inclusion of the f-wave component in the R-matrix analysis.

  3. r-Process Sensitivity Studies of Beta-Delayed Neutron Emissions

    NASA Astrophysics Data System (ADS)

    Giso, Mathew

    2014-09-01

    The r-process is a nucleosynthesis mechanism responsible for the formation of elements heavier than iron. It is unclear where in the galaxy the r-process occurs, but the two most likely locations are supernovae and neutron star mergers. This process is complex, and different initial conditions have a large affect on the resulting abundances of the elements produced. Using an r-process nuclear network code, we examined influence of beta-delayed neutron emissions (BDNE) probabilities. We tested single isotopes of every element with BDNE either maximized or turned off, while all other nuclei were held at their normal theoretical BDNE probability. The results were compared with a baseline, and we looked for local and global changes to the final abundance patterns. BDNE probabilities for nuclei 5-15 neutrons from stability were found to have the most substantial effects. Results with BDNE maximized had the most drastic changes from baselines. The r-process is a nucleosynthesis mechanism responsible for the formation of elements heavier than iron. It is unclear where in the galaxy the r-process occurs, but the two most likely locations are supernovae and neutron star mergers. This process is complex, and different initial conditions have a large affect on the resulting abundances of the elements produced. Using an r-process nuclear network code, we examined influence of beta-delayed neutron emissions (BDNE) probabilities. We tested single isotopes of every element with BDNE either maximized or turned off, while all other nuclei were held at their normal theoretical BDNE probability. The results were compared with a baseline, and we looked for local and global changes to the final abundance patterns. BDNE probabilities for nuclei 5-15 neutrons from stability were found to have the most substantial effects. Results with BDNE maximized had the most drastic changes from baselines. Union College, Davenport Scholarship, Dept. of Energy Grant: DE-FG02-05ER41398.

  4. Modeling the Production of Beta-Delayed Gamma Rays for the Detection of Special Nuclear Materials

    SciTech Connect

    Hall, J M; Pruet, J A; Brown, D A; Descalle, M; Hedstrom, G W; Prussin, S G

    2005-02-14

    The objective of this LDRD project was to develop one or more models for the production of {beta}-delayed {gamma} rays following neutron-induced fission of a special nuclear material (SNM) and to define a standardized formatting scheme which will allow them to be incorporated into some of the modern, general-purpose Monte Carlo transport codes currently being used to simulate inspection techniques proposed for detecting fissionable material hidden in sea-going cargo containers. In this report, we will describe a Monte Carlo model for {beta}-delayed {gamma}-ray emission following the fission of SNM that can accommodate arbitrary time-dependent fission rates and photon collection histories. The model involves direct sampling of the independent fission yield distributions of the system, the branching ratios for decay of individual fission products and spectral distributions representing photon emission from each fission product and for each decay mode. While computationally intensive, it will be shown that this model can provide reasonably detailed estimates of the spectra that would be recorded by an arbitrary spectrometer and may prove quite useful in assessing the quality of evaluated data libraries and identifying gaps in the libraries. The accuracy of the model will be illustrated by comparing calculated and experimental spectra from the decay of short-lived fission products following the reactions {sup 235}U(n{sub th}, f) and {sup 239}Pu(n{sub th}, f). For general-purpose transport calculations, where a detailed consideration of the large number of individual {gamma}-ray transitions in a spectrum may not be necessary, it will be shown that a simple parameterization of the {gamma}-ray source function can be defined which provides high-quality average spectral distributions that should suffice for calculations describing photons being transported through thick attenuating media. Finally, a proposal for ENDF-compatible formats that describe each of the models and

  5. Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor)

    1992-01-01

    This invention relates to a small particle selective emitter for converting thermal energy into narrow band radiation with high efficiency. The small particle selective emitter is used in combination with a photovoltaic array to provide a thermal to electrical energy conversion device. An energy conversion apparatus of this type is called a thermo-photovoltaic device. In the first embodiment, small diameter particles of a rare earth oxide are suspended in an inert gas enclosed between concentric cylinders. The rare earth oxides are used because they have the desired property of large emittance in a narrow wavelength band and small emittance outside the band. However, it should be emphasized that it is the smallness of the particles that enhances the radiation property. The small particle selective emitter is surrounded by a photovoltaic array. In an alternate embodiment, the small particle gas mixture is circulated through a thermal energy source. This thermal energy source can be a nuclear reactor, solar receiver, or combustor of a fossil fuel.

  6. Selective emitters

    NASA Astrophysics Data System (ADS)

    Chubb, Donald L.

    1992-01-01

    This invention relates to a small particle selective emitter for converting thermal energy into narrow band radiation with high efficiency. The small particle selective emitter is used in combination with a photovoltaic array to provide a thermal to electrical energy conversion device. An energy conversion apparatus of this type is called a thermo-photovoltaic device. In the first embodiment, small diameter particles of a rare earth oxide are suspended in an inert gas enclosed between concentric cylinders. The rare earth oxides are used because they have the desired property of large emittance in a narrow wavelength band and small emittance outside the band. However, it should be emphasized that it is the smallness of the particles that enhances the radiation property. The small particle selective emitter is surrounded by a photovoltaic array. In an alternate embodiment, the small particle gas mixture is circulated through a thermal energy source. This thermal energy source can be a nuclear reactor, solar receiver, or combustor of a fossil fuel.

  7. Development of activity pencil beam algorithm using measured distribution data of positron emitter nuclei generated by proton irradiation of targets containing (12)C, (16)O, and (40)Ca nuclei in preparation of clinical application.

    PubMed

    Miyatake, Aya; Nishio, Teiji; Ogino, Takashi

    2011-10-01

    The purpose of this study is to develop a new calculation algorithm that is satisfactory in terms of the requirements for both accuracy and calculation time for a simulation of imaging of the proton-irradiated volume in a patient body in clinical proton therapy. The activity pencil beam algorithm (APB algorithm), which is a new technique to apply the pencil beam algorithm generally used for proton dose calculations in proton therapy to the calculation of activity distributions, was developed as a calculation algorithm of the activity distributions formed by positron emitter nuclei generated from target nuclear fragment reactions. In the APB algorithm, activity distributions are calculated using an activity pencil beam kernel. In addition, the activity pencil beam kernel is constructed using measured activity distributions in the depth direction and calculations in the lateral direction. (12)C, (16)O, and (40)Ca nuclei were determined as the major target nuclei that constitute a human body that are of relevance for calculation of activity distributions. In this study, "virtual positron emitter nuclei" was defined as the integral yield of various positron emitter nuclei generated from each target nucleus by target nuclear fragment reactions with irradiated proton beam. Compounds, namely, polyethylene, water (including some gelatin) and calcium oxide, which contain plenty of the target nuclei, were irradiated using a proton beam. In addition, depth activity distributions of virtual positron emitter nuclei generated in each compound from target nuclear fragment reactions were measured using a beam ON-LINE PET system mounted a rotating gantry port (BOLPs-RGp). The measured activity distributions depend on depth or, in other words, energy. The irradiated proton beam energies were 138, 179, and 223 MeV, and measurement time was about 5 h until the measured activity reached the background level. Furthermore, the activity pencil beam data were made using the activity pencil

  8. Development of activity pencil beam algorithm using measured distribution data of positron emitter nuclei generated by proton irradiation of targets containing {sup 12}C, {sup 16}O, and {sup 40}Ca nuclei in preparation of clinical application

    SciTech Connect

    Miyatake, Aya; Nishio, Teiji; Ogino, Takashi

    2011-10-15

    Purpose: The purpose of this study is to develop a new calculation algorithm that is satisfactory in terms of the requirements for both accuracy and calculation time for a simulation of imaging of the proton-irradiated volume in a patient body in clinical proton therapy. Methods: The activity pencil beam algorithm (APB algorithm), which is a new technique to apply the pencil beam algorithm generally used for proton dose calculations in proton therapy to the calculation of activity distributions, was developed as a calculation algorithm of the activity distributions formed by positron emitter nuclei generated from target nuclear fragment reactions. In the APB algorithm, activity distributions are calculated using an activity pencil beam kernel. In addition, the activity pencil beam kernel is constructed using measured activity distributions in the depth direction and calculations in the lateral direction. {sup 12}C, {sup 16}O, and {sup 40}Ca nuclei were determined as the major target nuclei that constitute a human body that are of relevance for calculation of activity distributions. In this study, ''virtual positron emitter nuclei'' was defined as the integral yield of various positron emitter nuclei generated from each target nucleus by target nuclear fragment reactions with irradiated proton beam. Compounds, namely, polyethylene, water (including some gelatin) and calcium oxide, which contain plenty of the target nuclei, were irradiated using a proton beam. In addition, depth activity distributions of virtual positron emitter nuclei generated in each compound from target nuclear fragment reactions were measured using a beam ON-LINE PET system mounted a rotating gantry port (BOLPs-RGp). The measured activity distributions depend on depth or, in other words, energy. The irradiated proton beam energies were 138, 179, and 223 MeV, and measurement time was about 5 h until the measured activity reached the background level. Furthermore, the activity pencil beam data

  9. Impact of comprehensive simulations on trapped ion beta-delayed neutron spectroscopy

    NASA Astrophysics Data System (ADS)

    Siegl, Kevin; Aprahamian, A.; Scielzo, N. D.; Savard, G.; Clark, J. A.; Levand, A. F.; Burkey, M.; Caldwell, S.; Czeszumska, A.; Hirsh, T. Y.; Marley, S. T.; Morgan, G. E.; Norman, E. B.; Nystrom, A.; Orford, R.; Padgett, S.; Pérez Galván, A.; Sharma, K. S.; Strauss, S.; Wang, B. S.

    2015-10-01

    The decay of radioactive ions confined in an RF ion trap allows indirect measurements of beta-delayed neutron emission. This is accomplished by measuring the energy of the recoiling ion which can be much larger after neutron emission than from just beta decay. This method removes most systematic errors from neutron detection but introduces dependencies on specifics of the decay and interactions of the ion with the RF fields. Measurements were made of the 134-136Sb beta decays with this technique at Argonne National Laboratory using the Californium Rare Isotope Breeder Upgrade (CARIBU). A suite of simulations were developed to model the interaction of the decays and the influence of the trap fields on the recoiling ions. Measurements of these data can impact many fields, such as nuclear energy, nuclear astrophysics, and stockpile stewardship. Results of the simulations and analyses will be reported. Supported by NSF Grant # PHY-1419765, and U.S. DOE under the NEUP Project # 13-5485, Contract #s DE-AC02-06CH11357 (ANL) and DE-AC52-07NA27344 (LLNL), and Award # DE-NA0000979 (NNSA).

  10. A dedicated ion trap at CARIBU for beta-delayed neutron spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Barbara; Scielzo, N. D.; Norman, E. B.; Savard, G.; Clark, J. A.; Levand, A. F.; Aprahamian, A.; Burkey, M.; Caldwell, S.; Czeszumska, A.; Marley, S. T.; Morgan, G. E.; Nystrom, A.; Orford, R.; Padgett, S. W.; Perez Galvan, A.; Sharma, K. S.; Siegl, K.; Strauss, S.

    2015-10-01

    Trapped radioactive ions suspended in vacuum allow for a new way to perform beta-delayed neutron spectroscopy. Decay branching ratios and energy spectra of the emitted neutrons are inferred from a measurement of the nuclear recoil, thereby circumventing the many limitations associated with direct neutron detection. Plans for the development of a dedicated ion trap for experiments using the intense fission fragment beams from the Californium Rare Isotope Breeder Upgrade (CARIBU) facility at Argonne National Laboratory are summarized. The trap design has been guided by experience gained from recent ion-trap experiments measuring 137 - 138 , 140I, 134-136Sb, and 144-145Cs. The improved nuclear data that can be collected are needed in many fields of basic and applied science such as nuclear energy, nuclear astrophysics, and stockpile stewardship. Supported by NSF under Grant Number PHY-1419765 and by U.S. DOE under the Nuclear Energy University Program Project Number 13-5485, Contract Numbers DE-AC02-06CH11357 (ANL) and DE-AC52-07NA27344 (LLNL), and Award Number DE-NA0000979 (NNSA).

  11. Beta-delayed neutron emission studies with a C7LYC array at CARIBU

    NASA Astrophysics Data System (ADS)

    Wilson, Gemma; Chowdhury, Partha; Lister, Christopher; Brown, Tristan; Carpenter, Michael; Chillery, Thomas; Copp, Patrick; Doucet, Emery; Mitchell, Alan; Savard, Guy; Zhu, Shaofei

    2016-09-01

    This work is a study of β-delayed neutron and γ emission from 94Rb at CARIBU. Beta-delayed neutron emission studies are important in the astrophysical r-process, nuclear structure and for nuclear reactor safety and design. Approximately 150 γ rays are known in the daughter 94Sr, many of which are unplaced. An estimated 26% of γ rays are thought to be missing. The probability of β-delayed neutron emission in 94Sr is 10.2(2)%. Recently, substantial γ-decay from above the neutron separation energy in 94Rb has been reported. This research is aimed at understanding this high-lying γ-strength. The experiment employed the X-Array (a high efficiency HPGe clover array), SCANS (Small CLYC Array for Neutron Scattering) and the SATURN decay station (Scintillator And Tape Using Radioactive Nuclei) for γ, fast neutron and β-particle detection, respectively. Data were collected in a triggerless digital data acquisition system, with detected β , n , and γ events correlated offline. Techniques, analysis and first results will be discussed. Supported by the NNSA Stewardship Science Academic Alliance Program under Grant DE-NA00013008, and by US DoE, Office of Nuclear Physics, under DE-FG02-94ER40848.

  12. Beta-decay rate and beta-delayed neutron emission probability of improved gross theory

    NASA Astrophysics Data System (ADS)

    Koura, Hiroyuki

    2014-09-01

    A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for unmeasured nuclei are adopted from the KTUY nuclear mass formula, which is based on the spherical-basis method. Considering the properties of the integrated Fermi function, we can roughly categorized energy region of excited-state of a daughter nucleus into three regions: a highly-excited energy region, which fully affect a delayed neutron probability, a middle energy region, which is estimated to contribute the decay heat, and a region neighboring the ground-state, which determines the beta-decay rate. Some results will be given in the presentation. A theoretical study has been carried out on beta-decay rate and beta-delayed neutron emission probability. The gross theory of the beta decay is based on an idea of the sum rule of the beta-decay strength function, and has succeeded in describing beta-decay half-lives of nuclei overall nuclear mass region. The gross theory includes not only the allowed transition as the Fermi and the Gamow-Teller, but also the first-forbidden transition. In this work, some improvements are introduced as the nuclear shell correction on nuclear level densities and the nuclear deformation for nuclear strength functions, those effects were not included in the original gross theory. The shell energy and the nuclear deformation for

  13. Decay studies of nuclei near the proton drip line: /sup 35/Ca, /sup 31/Ar, /sup 69/Br, /sup 65/As

    SciTech Connect

    Reiff, J.E.

    1989-06-01

    Studies of new beta-delayed two-proton emitters and a search for ground state proton radioactivity in medium mass nuclei were performed using various experimental techniques in conjunction with several detection systems. A helium-jet transport system and three-element silicon telescopes were used to discover the existence and detect the decay of the first T/sub Z/ = /minus/5/2 nuclide, /sup 35/Ca. Two-proton emission from the T = 5/2 isobaric analog state in /sup 35/K at an excitation energy of 9.053 /plus minus/ 0.045 MeV, fed by the superallowed beta decay of /sup 35/Ca, resulted in transitions to both the ground state and first excited state of /sup 33/Cl. The corresponding two-proton sum energies were 4.089 /plus minus/ 0.030 MeV and 3.287 /plus minus/ 0.030 MeV. Measurements of the individual proton energies indicated the prevalence of a sequential decay mechanism. Using the isobaric multiplet mass equation, the mass excess of /sup 35/Ca was calculated to be 4.453 /plus minus/ 0.060 MeV. In order to study whose half-lives were too short for the helium-jet system, an in-beam recoil catcher wheel was constructed. The wheel speed can be varied to study nuclides whose half-lives range from 100 /mu/s to /approximately/250 ms. The first new decay observed with the wheel system and traditional /Delta/E-E telescopes was the beta-delayed two-proton emission from /sup 31/Ar. The two-proton sum energy of /approximately/7.5 MeV corresponds to a transition from the isobaric analog state in /sup 31/Cl to the ground state of /sup 29/P. The search for proton radioactivity required the development of low energy, particle identification detector telescopes. These telescopes, comprised of a gas /Delta/E and silicon E, were used in conjunction with the in-beam recoil catcher wheel to search for ground state proton emission from /sup 69/Br and /sup 65/As. 90 refs., 24 figs., 8 tabs.

  14. Controlled emittance blow up in the Tevatron

    SciTech Connect

    Tan, C.Y.; Steimel, J.; /Fermilab

    2009-04-01

    We have designed and commissioned a system which blows up the transverse emittance of the anti-proton beam without affecting the proton beam. It consists of a bandwidth limited noise source centered around the betatron tune, a power amplifier and a directional stripline kicker. The amount of blow up is controlled by the amount of energy delivered to the anti-protons betatron bands.

  15. Brownian Emitters

    NASA Astrophysics Data System (ADS)

    Tsekov, Roumen

    2016-06-01

    A Brownian harmonic oscillator, which dissipates energy either by friction or via emission of electromagnetic radiation, is considered. This Brownian emitter is driven by the surrounding thermo-quantum fluctuations, which are theoretically described by the fluctuation-dissipation theorem. It is shown how the Abraham-Lorentz force leads to dependence of the half-width on the peak frequency of the oscillator amplitude spectral density. It is found that for the case of a charged particle moving in vacuum at zero temperature, its root-mean-square velocity fluctuation is a universal constant, equal to roughly 1/18 of the speed of light. The relevant Fokker-Planck and Smoluchowski equations are also derived.

  16. Asymmetrical field emitter

    DOEpatents

    Fleming, James G.; Smith, Bradley K.

    1995-01-01

    Providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure.

  17. Asymmetrical field emitter

    DOEpatents

    Fleming, J.G.; Smith, B.K.

    1995-10-10

    A method is disclosed for providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure. 17 figs.

  18. beta. -delayed fission from /sup 256/Es/sup m/ and the level scheme of /sup 256/Fm

    SciTech Connect

    Hall, H.L.; Gregorich, K.E.; Henderson, R.A.; Lee, D.M.; Hoffman, D.C.; Bunker, M.E.; Fowler, M.M.; Lysaght, P.; Starner, J.W.; Wilhelmy, J.B.; and others

    1989-05-01

    The 7.6-h isotope /sup 256/Es/sup m/ was produced from a 2.5-..mu..g/cm/sup 2/ target of /sup 254/Es by the (t,p) reaction. The reaction products were separated radiochemically, and the decay properties of /sup 256/Es/sup m/ were determined via ..beta..-..gamma.., ..gamma..-..gamma.., and ..beta..-fission correlation techniques. From these measurements we were able to assign 57 ..gamma.. rays to 26 levels in the daughter /sup 256/Fm. An isomeric level was observed at 1425 keV and assigned a spin and parity of 7/sup -/. This level has a t/sub 1/2/ of (70 +- 5) ns and we observed two ..beta..-delayed fissions with delay times in the proper time range to be associated with fission from this level. This gives a ..beta..-delayed fission probability of 2 x 10/sup -5/ for this level and a partial fission half-life of 0.8/sub -0.7//sup +8.8/ ms at the 95% confidence level.

  19. Emittance growth due to Tevatron flying wires

    SciTech Connect

    Syphers, M; Eddy, Nathan

    2004-06-01

    During Tevatron injection, Flying Wires have been used to measure the transverse beam size after each transfer from the Main Injector in order to deduce the transverse emittances of the proton and antiproton beams. This amounts to 36 + 9 = 45 flies of each of 3 wire systems, with an individual wire passing through each beam bunch twice during a single ''fly''. below they estimate the emittance growth induced by the interaction of the wires with the particles during these measurements. Changes of emittance from Flying Wire measurements conducted during three recent stores are compared with the estimations.

  20. Very Low Energy Protons From the Beta Decay of Proton Rich Nuclei For Nuclear Astrophysics

    SciTech Connect

    Simmons, E.; Trache, L.; Banu, A.; McCleskey, M.; Roeder, B.; Spiridon, A.; Tribble, R. E.; Saastamoinen, A.; Aysto, J.; Davinson, T.; Woods, P. J.; Lotay, G. J.

    2010-03-01

    We have developed a new experimental technique to measure very low energy protons from beta-delayed p-decay of proton-rich nuclei produced and separated with the MARS recoil spectrometer at TAMU. Recently we have investigated the beta-delayed p-decays of {sup 23}Al and {sup 31}Cl and obtained information on the resonances in the reactions {sup 22}Na(p,gamma){sup 23}Mg and {sup 30}P(p,gamma){sup 31}S, respectively. These reactions are important in explosive H-burning in Novae. A simple setup consisting of a telescope made of a thin double sided Si strip detector (p-detector) backed or sandwiched between two thick Si detectors (beta-detectors) was designed. We studied two different p-detectors and found that the thinner detectors with a small cell size are best to measure proton energies as low as 2-300 keV.

  1. Emittance Theory for Thin Film Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

    1994-01-01

    Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

  2. Emittance Theory for Cylindrical Fiber Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1998-01-01

    A fibrous rare earth selective emitter is approximated as an infinitely long cylinder. The spectral emittance, epsilon(lambda), is obtained by solving the radiative transfer equations with appropriate boundary conditions and uniform temperature. For optical depths, Kappa(R) = alpha(lambda)R, where alpha(lambda) is the extinction coefficient and R is the cylinder radius, greater than 1 the spectral emittance is nearly at its maximum value. There is an optimum cylinder radius, R(opt), for maximum emitter efficiency, eta(E). Values for R(opt) are strongly dependent on the number of emission bands of the material. The optimum radius decreases slowly with increasing emitter temperature, while the maximum efficiency and useful radiated power increase rapidly with increasing temperature.

  3. Floating emitter solar cell

    NASA Technical Reports Server (NTRS)

    Chih, Sah (Inventor); Cheng, Li-Jen (Inventor)

    1987-01-01

    A front surface contact floating emitter solar cell transistor is provided in a semiconductor body (n-type), in which floating emitter sections (p-type) are diffused or implanted in the front surface. Between the emitter sections, a further section is diffused or implanted in the front surface, but isolated from the floating emitter sections, for use either as a base contact to the n-type semiconductor body, in which case the section is doped n+, or as a collector for the adjacent emitter sections.

  4. Monte Carlo Models for the Production of beta-delayed Gamma Rays Following Fission of Special Nuclear Materials

    SciTech Connect

    Pruet, J; Prussin, S; Descalle, M; Hall, J

    2004-02-03

    A Monte Carlo method for the estimation of {beta}-delayed {gamma}-ray spectra following fission is described that can accommodate an arbitrary time-dependent fission rate and photon collection history. The method invokes direct sampling of the independent fission yield distributions of the fissioning system, the branching ratios for decay of individual fission products and the spectral distributions for photon emission for each decay mode. Though computationally intensive, the method can provide a detailed estimate of the spectrum that would be recorded by an arbitrary spectrometer, and can prove useful in assessing the quality of evaluated data libraries, for identifying gaps in these libraries, etc. The method is illustrated by a first comparison of calculated and experimental spectra from decay of short-lived fission products following the reactions {sup 235}U(n{sub th}, f) and {sup 239}Pu(n{sub th}, f). For general purpose transport calculations, where detailed consideration of the large number of individual {gamma}-ray transitions in a spectrum may be unnecessary, it is shown that an accurate and simple parameterization of a {gamma}-ray source function can be obtained. These parametrizations should provide high-quality average spectral distributions that should prove useful in calculations describing photons escaping from thick attenuating media.

  5. Photonically Engineered Incandescent Emitter

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2005-03-22

    A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

  6. Photonically engineered incandescent emitter

    DOEpatents

    Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

    2003-08-26

    A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

  7. Quantitative deconvolution of human thermal infrared emittance.

    PubMed

    Arthur, D T J; Khan, M M

    2013-01-01

    The bioheat transfer models conventionally employed in etiology of human thermal infrared (TIR) emittance rely upon two assumptions; universal graybody emissivity and significant transmission of heat from subsurface tissue layers. In this work, a series of clinical and laboratory experiments were designed and carried out to conclusively evaluate the validity of the two assumptions. Results obtained from the objective analyses of TIR images of human facial and tibial regions demonstrated significant variations in spectral thermophysical properties at different anatomic locations on human body. The limited validity of the two assumptions signifies need for quantitative deconvolution of human TIR emittance in clinical, psychophysiological and critical applications. A novel approach to joint inversion of the bioheat transfer model is also introduced, levering the deterministic temperature-dependency of proton resonance frequency in low-lipid human soft tissue for characterizing the relationship between subsurface 3D tissue temperature profiles and corresponding TIR emittance.

  8. Observation of Doppler broadening in β -delayed proton- γ decay

    DOE PAGES

    Schwartz, S. B.; Wrede, C.; Bennett, M. B.; ...

    2015-09-14

    Background: The Doppler broadening of gamma-ray peaks is due to nuclear recoil from beta-delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using beta-delayed proton emission or applied to a recoil heavier than A = 10. Purpose: To test and apply this Doppler broadening method using gamma-ray peaks from the P-26(beta p gamma)Al-25 decay sequence. Methods: A fast beam of P-26 was implanted into a planar Ge detector, which was used as a P-26 beta-decay trigger. The SeGA array of high-purity Ge detectors was used to detect gamma rays frommore » the P-26(beta p gamma)Al-25 decay sequence. Results: Radiative Doppler broadening in beta-delayed proton-gamma decay was observed for the first time. Moreover, the Doppler broadening analysis method was verified using the 1613-keV gamma-ray line for which the proton energies were previously known. The 1776-keV gamma ray de-exciting the 2720 keV Al-25 level was observed in P-26(beta p gamma)Al-25 decay for the first time and used to determine that the center-of-mass energy of the proton emission feeding the 2720-keV level is 5.1 +/- 1.0 (stat.) +/- 0.6 (syst.) MeV, corresponding to a Si-26 excitation energy of 13.3 +/- 1.0 (stat.) +/- 0.6 (syst.) MeV for the proton-emitting level. Conclusions: Finally, the Doppler broadening method has been demonstrated to provide practical measurements of the energies for beta-delayed nucleon emissions populating excited states of nuclear recoils at least as heavy as A = 25.« less

  9. Diamond fiber field emitters

    DOEpatents

    Blanchet-Fincher, Graciela B.; Coates, Don M.; Devlin, David J.; Eaton, David F.; Silzars, Aris K.; Valone, Steven M.

    1996-01-01

    A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.

  10. Study of proton radioactivities

    SciTech Connect

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

    1995-08-01

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

  11. Pulsed hybrid field emitter

    DOEpatents

    Sampayan, S.E.

    1998-03-03

    A hybrid emitter exploits the electric field created by a rapidly depoled ferroelectric material. Combining the emission properties of a planar thin film diamond emitter with a ferroelectric alleviates the present technological problems associated with both types of emitters and provides a robust, extremely long life, high current density cathode of the type required by emerging microwave power generation, accelerator technology and display applications. This new hybrid emitter is easy to fabricate and not susceptible to the same failures which plague microstructure field emitter technology. Local electrode geometries and electric field are determined independently from those for optimum transport and brightness preservation. Due to the large amount of surface charge created on the ferroelectric, the emitted electrons have significant energy, thus eliminating the requirement for specialized phosphors in emissive flat-panel displays. 11 figs.

  12. Pulsed hybrid field emitter

    DOEpatents

    Sampayan, Stephen E.

    1998-01-01

    A hybrid emitter exploits the electric field created by a rapidly depoled ferroelectric material. Combining the emission properties of a planar thin film diamond emitter with a ferroelectric alleviates the present technological problems associated with both types of emitters and provides a robust, extremely long life, high current density cathode of the type required by emerging microwave power generation, accelerator technology and display applications. This new hybrid emitter is easy to fabricate and not susceptible to the same failures which plague microstructure field emitter technology. Local electrode geometries and electric field are determined independently from those for optimum transport and brightness preservation. Due to the large amount of surface charge created on the ferroelectric, the emitted electrons have significant energy, thus eliminating the requirement for specialized phosphors in emissive flat-panel displays.

  13. Emittance growth saturation effect in synchrotron machines due to point-like perturbations

    SciTech Connect

    Lopez, G.; Chen, S.

    1993-11-01

    Analytical estimation of the transverse emittance growth due to a point-like perturbation is performed for a proton synchrotron machine. This emittance growth is caused by the tune spread within the bunch. However, the emittance growth suffers a saturation effect caused by the same tune spread. Computer simulations on the emittance growth due to resistive wall instabilities and feedback systems verify qualitatively this emittance growth saturation effect. These simulations were accomplished in the Medium Energy Booster of the Superconducting Super Collider using the TADIMMI computer code.

  14. Stimulated longitudinal emittance growth in the Main Ring

    SciTech Connect

    Jackson, G.; Ieiri, T.

    1989-03-01

    During fixed target operations -- beam intensity is limited by coherent instabilities in both the Main Ring and Tevatron. The growth rates for instabilities are generally inversely proportional to the proton bunch length. Since fixed target operations are insensitive to the longitudinal emittance of the beams, bunch spreaders are employed to increase the emittance, and hence the bunch length. Emittance growth is stimulated by injecting noise onto either the RF phase or amplitude control voltages. Test results of the efficiency of various stimulation schemes are reported. The design of a bunch length monitor, used to measure the effect of the bunch spreader, is also presented. 12 refs., 5 figs.

  15. The DIORAMA Neutron Emitter

    SciTech Connect

    Terry, James Russell

    2016-05-05

    Emission of neutrons in a given event is modeled by the DioramaEmitterNeutron object, a subclass of the abstract DioramaEmitterModule object. The GenerateEmission method of this object is the entry point for generation of a neutron population for a given event. Shown in table 1, this method requires a number of parameters to be defined in the event definition.

  16. DIAMOND SECONDARY EMITTER

    SciTech Connect

    BEN-ZVI, I.; RAO, T.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

    2005-10-09

    We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron Yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.

  17. First Compilation and Evaluation of Beta-Delayed Neutron Emission Probabilities and Associated Half-Lives for A ≤ 72 Nuclei

    NASA Astrophysics Data System (ADS)

    Birch, M.; Singh, B.; Abriola, D.; Dillmann, I.; Johnson, T. D.; McCutchan, E. A.; Sonzogni, A. A.

    2014-06-01

    A comprehensive compilation and evaluation of beta-delayed neutron (β- n) emission probabilities, Pn, and associated half-lives for A ≤ 72 nuclei has been performed for the first time. The recommended values have been used to analyze the systematics of β- n emission in this region. The ratio Pn /T1/2 is better correlated with the Q-value of the β- n decay mode than the previously proposed Kratz-Herrmann Formula (KHF). The recommended values are also compared with theoretical quasi-particle random phase approximation (QRPA) calculations.

  18. {beta}-decay half-lives and {beta}-delayed neutron emission probabilities of nuclei in the region A < or approx. 110, relevant for the r process

    SciTech Connect

    Pereira, J.; Galaviz, D.; Matos, M.; Montes, F.; Hennrich, S.; Kessler, R.; Schertz, F.; Aprahamian, A.; Quinn, M.; Woehr, A.; Arndt, O.; Pfeiffer, B.; Becerril, A.; Elliot, T.; Estrade, A.; Lorusso, G.; Schatz, H.; Kratz, K.-L.; Mantica, P. F.; Moeller, P.

    2009-03-15

    Measurements of {beta}-decay properties of A < or approx. 110 r-process nuclei have been completed at the National Superconducting Cyclotron Laboratory at Michigan State University. {beta}-decay half-lives for {sup 105}Y, {sup 106,107}Zr, and {sup 111}Mo, along with {beta}-delayed neutron emission probabilities of {sup 104}Y, {sup 109,110}Mo and upper limits for {sup 105}Y, {sup 103-107}Zr, and {sup 108,111}Mo have been measured for the first time. Studies on the basis of the quasi-random-phase approximation are used to analyze the ground-state deformation of these nuclei.

  19. Nanoelectrospray Emitter Arrays Providing Inter-Emitter Electric Field Uniformity

    PubMed Central

    Kelly, Ryan T.; Page, Jason S.; Marginean, Ioan; Tang, Keqi; Smith, Richard D.

    2008-01-01

    Arrays of electrospray ionization (ESI) emitters have been reported previously as a means of enhancing ionization efficiency or signal intensity. A key challenge when working with multiple, closely spaced ESI emitters is overcoming the deleterious effects caused by electrical interference among neighboring emitters. Individual emitters can experience different electric fields depending on their relative position in the array, such that it becomes difficult to operate all of the emitters optimally for a given applied potential. In this work, we have developed multi-nanoESI emitters arranged with a circular pattern, which enable the constituent emitters to experience a uniform electric field. The performance of the circular emitter array was compared to a single emitter and to a previously developed linear emitter array, which verified that improved electric field uniformity was achieved with the circular arrangement. The circular arrays were also interfaced with a mass spectrometer via a matching multi-capillary inlet, and the results were compared with those obtained using a single emitter. By minimizing inter-emitter electric field inhomogeneities, much larger arrays having closer emitter spacing should be feasible. PMID:18553942

  20. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, Anthony F.

    1999-01-01

    Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area.

  1. Cancer from internal emitters

    SciTech Connect

    Boecker, B.B.; Griffith, W.C. Jr.

    1995-10-01

    Irradiation from internal emitters, or internally deposited radionuclides, is an important component of radiation exposures encountered in the workplace, home, or general environment. Long-term studies of human populations exposed to various internal emitters by different routes of exposure are producing critical information for the protection of workers and members of the general public. The purpose of this report is to examine recent developments and discuss their potential importance for understanding lifetime cancer risks from internal emitters. The major populations of persons being studied for lifetime health effects from internally deposited radionuclides are well known: Lung cancer in underground miners who inhaled Rn progeny, liver cancer from persons injected with the Th-containing radiographic contrast medium Thorotrast, bone cancer from occupational or medical intakes of {sup 226}Ra or medical injections of {sup 224}Ra, and thyroid cancer from exposures to iodine radionuclides in the environment or for medical purposes.

  2. RFI emitter location techniques

    NASA Technical Reports Server (NTRS)

    Rao, B. L. J.

    1973-01-01

    The possibility is discussed of using Doppler techniques for determining the location of ground based emitters causing radio frequency interference with low orbiting satellites. An error analysis indicates that it is possible to find the emitter location within an error range of 2 n.mi. The parameters which determine the required satellite receiver characteristic are discussed briefly along with the non-real time signal processing which may by used in obtaining the Doppler curve. Finally, the required characteristics of the satellite antenna are analyzed.

  3. Effect of Temperature Gradient on Thick Film Selective Emitter Emittance

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Good, Brian S.; Clark, Eric B.; Chen, Zheng

    1997-01-01

    A temperature gradient across a thick (greater than or equal to .1 mm) film selective emitter will produce a significant reduction in the spectral emittance from the no temperature gradient case. Thick film selective emitters of rare earth doped host materials such as yttrium-aluminum-garnet (YAG) are examples where temperature gradient effects are important. In this paper a model is developed for the spectral emittance assuming a linear temperature gradient across the film. Results of the model indicate that temperature gradients will result in reductions the order of 20% or more in the spectral emittance.

  4. First Compilation and Evaluation of Beta-Delayed Neutron Emission Probabilities and Associated Half-Lives for A ≤ 72 Nuclei

    SciTech Connect

    Birch, M.; Singh, B.; Abriola, D.; Dillmann, I.; Johnson, T.D.; McCutchan, E.A.; Sonzogni, A.A.

    2014-06-15

    A comprehensive compilation and evaluation of beta-delayed neutron (β{sup −}n) emission probabilities, P{sub n}, and associated half-lives for A ≤ 72 nuclei has been performed for the first time. The recommended values have been used to analyze the systematics of β{sup −}n emission in this region. The ratio P{sub n}/T{sub 1/2} is better correlated with the Q-value of the β{sup −}n decay mode than the previously proposed Kratz-Herrmann Formula (KHF). The recommended values are also compared with theoretical quasi-particle random phase approximation (QRPA) calculations.

  5. First Compilation and Evaluation of Beta-Delayed Neutron Emission Probabilities and Associated Half-Lives for A ≤72 Nuclei

    SciTech Connect

    Birch, M.; Singh, B.; Abriola, D.; Dillmann, I.; Johnson, T.; McCutchan, E. A.; Sonzogni, A. A.

    2014-06-01

    After a comprehensive compilation and evaluation of beta-delayed neutron (β-n) emission probabilities, Pn, and associated half-lives for A ≤ 72 nuclei has been performed for the first time. The recommended values have been used to analyze the systematics of β-nemission in this region. The ratio Pn/T1/2 is better correlated with the Q-value of the β-n decay mode than the previously proposed Kratz-Herrmann Formula (KHF). Moreover, the recommended values are also compared with theoretical quasi-particle random phase approximation (QRPA) calculations.

  6. Reappraisal of solid selective emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1990-01-01

    New rare earth oxide emitters show greater efficiency than previous emitters. As a result, based on a simple model the efficiency of these emitters was calculated. Results indicate that the emission band of the selective emitter must be at relatively low energy (less than or equal to .52 eV) to obtain maximum efficiency at moderate emitter temperatures (less than or equal to 1500 K). Thus low bandgap energy PV materials are required to obtain an efficient thermophotovoltaic (TPV) system. Of the 4 specific rare earths (Nd, Ho, Er, Yb) studied Ho has the largest efficiency at moderate temperatures (72 percent at 1500 K). A comparison was made between a selective emitter TPV system and a TPV system that uses a thermal emitter plus a band pass filter to make the thermal emitter behave like a selective emitter. Results of the comparison indicate that only for very optimistic filter and thermal emitter properties will the filter TPV system have a greater efficiency than the selective emitter system.

  7. Rare Earth Garnet Selective Emitter

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

  8. Gamow-Teller {beta}{sup +} decay of deformed nuclei near the proton drip line

    SciTech Connect

    Frisk, F.; Hamamoto, I.; Zhang, X.Z. |

    1995-11-01

    Using a quasiparticle Tamm-Dancoff approximation (TDA) based on deformed Hartree-Fock (HF) calculations with Skyrme interactions, the distribution of the Gamow-Teller (GT) {beta}{sup +} decay strength is estimated for the HF local minima of even-even deformed nuclei near the proton drip line in the region of 28{lt}{ital Z}{lt}66. The distribution often depends sensitively on the nuclear shape (namely, oblate or prolate). In the region of {ital Z}{lt}50 the possibility of observing {beta}-delayed proton emission depends sensitively on the excess of {ital Z} over {ital Z}={ital N}. In the region of {ital Z}{gt}50 almost the entire estimated GT strength is found to lie below the ground states of the even-even mother nuclei, and the observation of the total GT strength by {beta}-delayed charged-particle(s) emission will be of essential importance.

  9. Evidence for Gamow-Teller Decay of ^{78}Ni Core from Beta-Delayed Neutron Emission Studies.

    PubMed

    Madurga, M; Paulauskas, S V; Grzywacz, R; Miller, D; Bardayan, D W; Batchelder, J C; Brewer, N T; Cizewski, J A; Fijałkowska, A; Gross, C J; Howard, M E; Ilyushkin, S V; Manning, B; Matoš, M; Mendez, A J; Miernik, K; Padgett, S W; Peters, W A; Rasco, B C; Ratkiewicz, A; Rykaczewski, K P; Stracener, D W; Wang, E H; Wolińska-Cichocka, M; Zganjar, E F

    2016-08-26

    The β-delayed neutron emission of ^{83,84}Ga isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to ^{78}Ni core-excited states in ^{83,84}Ge favored by shell effects. We developed shell model calculations in the proton fpg_{9/2} and neutron extended fpg_{9/2}+d_{5/2} valence space using realistic interactions that were used to understand measured β-decay lifetimes. We conclude that enhanced, concentrated β-decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β-delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models.

  10. Evidence for Gamow-Teller Decay of 78Ni Core from Beta-Delayed Neutron Emission Studies

    NASA Astrophysics Data System (ADS)

    Madurga, M.; Paulauskas, S. V.; Grzywacz, R.; Miller, D.; Bardayan, D. W.; Batchelder, J. C.; Brewer, N. T.; Cizewski, J. A.; Fijałkowska, A.; Gross, C. J.; Howard, M. E.; Ilyushkin, S. V.; Manning, B.; Matoš, M.; Mendez, A. J.; Miernik, K.; Padgett, S. W.; Peters, W. A.; Rasco, B. C.; Ratkiewicz, A.; Rykaczewski, K. P.; Stracener, D. W.; Wang, E. H.; Wolińska-Cichocka, M.; Zganjar, E. F.

    2016-08-01

    The β -delayed neutron emission of Ga,8483 isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to 78Ni core-excited states in Ge,8483 favored by shell effects. We developed shell model calculations in the proton f p g9 /2 and neutron extended f p g9 /2+d5 /2 valence space using realistic interactions that were used to understand measured β -decay lifetimes. We conclude that enhanced, concentrated β -decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β -delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models.

  11. Rare earth garnet selective emitter

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

    1994-01-01

    Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

  12. Study of the production yields of 18F, 11C, 13N and 15O positron emitters from plasma-laser proton sources at ELI-Beamlines for labeling of PET radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Amato, Ernesto; Italiano, Antonio; Margarone, Daniele; Pagano, Benedetta; Baldari, Sergio; Korn, Georg

    2016-03-01

    The development of novel compact PET radionuclide production systems is of great interest to promote the diffusion of PET diagnostics, especially in view of the continuous development of microfluidics labeling approaches. We studied the feasibility to produce clinically-relevant amounts of PET isotopes by means of laser-accelerated proton sources such that expected at the ELI-Beamlines facility. 18F, 11C, 13N and 15O production yields were calculated through the TALYS software, by taking into account the broad proton spectra expected. With the hypothesized proton fluencies, clinically-relevant amounts of radionuclides can be obtained, suitable to prepare single doses of 18F-, 11C- and 13N-labeled radiopharmaceuticals exploiting fast and efficient microfluidic labeling systems.

  13. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    DOEpatents

    Wang, Daojing; Yang, Peidong; Kim, Woong; Fan, Rong

    2011-09-20

    Novel and significantly simplified procedures for fabrication of fully integrated nanoelectrospray emitters have been described. For nanofabricated monolithic multinozzle emitters (NM.sup.2 emitters), a bottom up approach using silicon nanowires on a silicon sliver is used. For microfabricated monolithic multinozzle emitters (M.sup.3 emitters), a top down approach using MEMS techniques on silicon wafers is used. The emitters have performance comparable to that of commercially-available silica capillary emitters for nanoelectrospray mass spectrometry.

  14. Amorphous-diamond electron emitter

    DOEpatents

    Falabella, Steven

    2001-01-01

    An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

  15. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, A.F.

    1999-03-16

    Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays is disclosed. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area. 12 figs.

  16. Tuneable superradiant thermal emitter assembly

    NASA Astrophysics Data System (ADS)

    Mallawaarachchi, Sudaraka; Premaratne, Malin; Gunapala, Sarath D.; Maini, Philip K.

    2017-04-01

    Superradiance is a signature effect in quantum photonics that explains the collective enhancement of emission power by a factor of N2 when N emitters are placed in subwavelength proximity. Although the effect is inherently transient, successful attempts have been made to sustain it in the steady-state regime. Until recently, the effects of superradiance were not considered to be applicable to thermal emitters due to their intrinsic incoherent nature. Novel nanophotonic thermal emitters display favorable coherent characteristics that enable them to obey principles of superradiance. However, published analytical work on conventional superradiant thermal emitter assemblies shows an anomalous power scaling of 1 /N , and therefore increasing the number of thermal emitters leads to a degeneration of power at resonance. This phenomenon immediately renders the effect of thermal superradiance futile since it cannot outperform noncoupled emitters in the steady-state regime. We propose an alternative assembly of thermal emitters with specific features that improves the power scaling while maintaining the effects of superradiance. In essence, we show that our emitter assembly achieves superior power delivery over conventional noncoupled emitter systems at resonance. Additionally, this assembly has the ability to be tuned to operate at specific resonant frequencies, which is a vital requirement for applications such as photothermal cancer therapy.

  17. Observation of Doppler broadening in β -delayed proton- γ decay

    SciTech Connect

    Schwartz, S. B.; Wrede, C.; Bennett, M. B.; Liddick, S. N.; Pérez-Loureiro, D.; Bowe, A.; Chen, A. A.; Chipps, K. A.; Cooper, N.; Irvine, D.; McNeice, E.; Montes, F.; Naqvi, F.; Ortez, R.; Pain, S. D.; Pereira, J.; Prokop, C.; Quaglia, J.; Quinn, S. J.; Sakstrup, J.; Santia, M.; Shanab, S.; Simon, A.; Spyrou, A.; Thiagalingam, E.

    2015-09-14

    Background: The Doppler broadening of gamma-ray peaks is due to nuclear recoil from beta-delayed nucleon emission can be used to measure the energies of the nucleons. This method has never been tested using beta-delayed proton emission or applied to a recoil heavier than A = 10. Purpose: To test and apply this Doppler broadening method using gamma-ray peaks from the P-26(beta p gamma)Al-25 decay sequence. Methods: A fast beam of P-26 was implanted into a planar Ge detector, which was used as a P-26 beta-decay trigger. The SeGA array of high-purity Ge detectors was used to detect gamma rays from the P-26(beta p gamma)Al-25 decay sequence. Results: Radiative Doppler broadening in beta-delayed proton-gamma decay was observed for the first time. Moreover, the Doppler broadening analysis method was verified using the 1613-keV gamma-ray line for which the proton energies were previously known. The 1776-keV gamma ray de-exciting the 2720 keV Al-25 level was observed in P-26(beta p gamma)Al-25 decay for the first time and used to determine that the center-of-mass energy of the proton emission feeding the 2720-keV level is 5.1 +/- 1.0 (stat.) +/- 0.6 (syst.) MeV, corresponding to a Si-26 excitation energy of 13.3 +/- 1.0 (stat.) +/- 0.6 (syst.) MeV for the proton-emitting level. Conclusions: Finally, the Doppler broadening method has been demonstrated to provide practical measurements of the energies for beta-delayed nucleon emissions populating excited states of nuclear recoils at least as heavy as A = 25.

  18. EMITTANCE COMPENSATION FOR MAGNETIZED BEAMS

    SciTech Connect

    KEWISCH,J.; CHANG, X.

    2007-06-25

    Emittance compensation is a well established technique for minimizing the emittance of an electron beam from a RF photo-cathode gun. Longitudinal slices of a bunch have a small emittance, but due to the longitudinal charge distribution of the bunch and time dependent RF fields they are not focused in the same way, so that the direction of their phase ellipses diverges in phase space and the projected emittance is much larger. Emittance compensation reverses the divergence. At the location where the slopes of the phase ellipses coincide the beam is accelerated, so that the space charge forces are reduced. A recipe for emittance compensation is given in. For magnetized beams (where the angular momentum is non-zero) such emittance compensation is not sufficient because variations in the slice radius lead to variations in the angular speed and therefore to an increase of emittance in the rotating game. We describe a method and tools for a compensation that includes the beam magnetization.

  19. Thin-Film Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Lowe, Roland A.

    1993-01-01

    Direct conversion of thermal energy into electrical energy using a photovoltaic cell is called thermophotovoltaic energy conversion. One way to make this an efficient process is to have the thermal energy source be an efficient selective emitter of radiation. The emission must be near the band-gap energy of the photovoltaic cell. One possible method to achieve an efficient selective emitter is the use of a thin film of rare-earth oxides. The determination of the efficiency of such an emitter requires analysis of the spectral emittance of the thin film including scattering and reflectance at the vacuum-film and film-substrate interfaces. Emitter efficiencies (power emitted in emission band/total emitted power) in the range 0.35-0.7 are predicted. There is an optimum optical depth to obtain maximum efficiency. High emitter efficiencies are attained only for low (less than 0.05) substrate emittance values, both with and without scattering. The low substrate emittance required for high efficiency limits the choice of substrate materials to highly reflective metals or high-transmission materials such as sapphire.

  20. Emittance compensation in split photoinjectors

    NASA Astrophysics Data System (ADS)

    Floettmann, Klaus

    2017-01-01

    The compensation of correlated emittance contributions is of primary importance to optimize the performance of high brightness photoinjectors. While only extended numerical simulations can capture the complex beam dynamics of space-charge-dominated beams in sufficient detail to optimize a specific injector layout, simplified models are required to gain a deeper understanding of the involved dynamics, to guide the optimization procedure, and to interpret experimental results. In this paper, a slice envelope model for the emittance compensation process in a split photoinjector is presented. The emittance term is included in the analytical solution of the beam envelope in a drift, which is essential to take the emittance contribution due to a beam size mismatch into account. The appearance of two emittance minima in the drift is explained, and the matching into the booster cavity is discussed. A comparison with simulation results points out effects which are not treated in the envelope model, such as overfocusing and field nonlinearities.

  1. Two-Proton Radioactivity as a Tool for Nuclear Structure

    NASA Astrophysics Data System (ADS)

    Blank, B.; Ascher, P.; Audirac, L.; Giovinazzo, J.; Adimi, N.; Canchel, G.; Delalee, F.; Demonchy, C. E.; Dossat, C.; Grévy, S.; Hay, L.; Huikari, J.; Kurtukian-Nieto, T.; Leblanc, S.; Matea, I.; Pedroza, J.-L.; Pibernat, J.; Serani, L.; de Oliveira Santos, F.; Perrot, L.; Srivastava, P. C.; Stodel, C.; Thomas, J.-C.; Borcea, C.; Companis, I.; Brown, B. A.; Grigorenko, L. V.

    2013-09-01

    The decay of the ground-state two-proton emitters 45Fe and 54Zn was studied with a time-projection chamber and the emission of two protons was unambiguously identified. The total decay energy and the half-life measured agree with the results from previous experiments. The energy sharing between the two protons and their relative emission angle was determined with a time projection chamber and is compared to model predictions. In parallel, we observed directly β-delayed two- and three-proton emission from 43Cr, a known β-delayed two-proton emitter.

  2. Highly directional thermal emitter

    DOEpatents

    Ribaudo, Troy; Shaner, Eric A; Davids, Paul; Peters, David W

    2015-03-24

    A highly directional thermal emitter device comprises a two-dimensional periodic array of heavily doped semiconductor structures on a surface of a substrate. The array provides a highly directional thermal emission at a peak wavelength between 3 and 15 microns when the array is heated. For example, highly doped silicon (HDSi) with a plasma frequency in the mid-wave infrared was used to fabricate nearly perfect absorbing two-dimensional gratings structures that function as highly directional thermal radiators. The absorption and emission characteristics of the HDSi devices possessed a high degree of angular dependence for infrared absorption in the 10-12 micron range, while maintaining high reflectivity of solar radiation (.about.64%) at large incidence angles.

  3. Towards graphane field emitters.

    PubMed

    Ding, Shuyi; Cole, Matthew T; Li, Chi; Zhou, Yanhuai; Collins, Clare M; Kang, Moon H; Parmee, Richard J; Lei, Wei; Zhang, Xiaobing; Dai, Qing; Milne, William I; Wang, Baoping

    2015-12-10

    We report on the improved field emission performance of graphene foam (GF) following transient exposure to hydrogen plasma. The enhanced field emission mechanism associated with hydrogenation has been investigated using Fourier transform infrared spectroscopy, plasma spectrophotometry, Raman spectroscopy, and scanning electron microscopy. The observed enhanced electron emissionhas been attributed to an increase in the areal density of lattice defects and the formation of a partially hydrogenated, graphane-like material. The treated GF emitter demonstrated a much reduced macroscopic turn-on field (2.5 V μm(-1)), with an increased maximum current density from 0.21 mA cm(-2) (pristine) to 8.27 mA cm(-2) (treated). The treated GFs vertically orientated protrusions, after plasma etching, effectively increased the local electric field resulting in a 2.2-fold reduction in the turn-on electric field. The observed enhancement is further attributed to hydrogenation and the subsequent formation of a partially hydrogenated structured 2D material, which advantageously shifts the emitter work function. Alongside augmentation of the nominal crystallite size of the graphitic superstructure, surface bound species are believed to play a key role in the enhanced emission. The hydrogen plasma treatment was also noted to increase the emission spatial uniformity, with an approximate four times reduction in the per unit area variation in emission current density. Our findings suggest that plasma treatments, and particularly hydrogen and hydrogen-containing precursors, may provide an efficient, simple, and low cost means of realizing enhanced nanocarbon-based field emission devices via the engineered degradation of the nascent lattice, and adjustment of the surface work function.

  4. Towards graphane field emitters

    PubMed Central

    Ding, Shuyi; Li, Chi; Zhou, Yanhuai; Collins, Clare M.; Kang, Moon H.; Parmee, Richard J.; Zhang, Xiaobing; Milne, William I.; Wang, Baoping

    2015-01-01

    We report on the improved field emission performance of graphene foam (GF) following transient exposure to hydrogen plasma. The enhanced field emission mechanism associated with hydrogenation has been investigated using Fourier transform infrared spectroscopy, plasma spectrophotometry, Raman spectroscopy, and scanning electron microscopy. The observed enhanced electron emissionhas been attributed to an increase in the areal density of lattice defects and the formation of a partially hydrogenated, graphane-like material. The treated GF emitter demonstrated a much reduced macroscopic turn-on field (2.5 V μm–1), with an increased maximum current density from 0.21 mA cm–2 (pristine) to 8.27 mA cm–2 (treated). The treated GFs vertically orientated protrusions, after plasma etching, effectively increased the local electric field resulting in a 2.2-fold reduction in the turn-on electric field. The observed enhancement is further attributed to hydrogenation and the subsequent formation of a partially hydrogenated structured 2D material, which advantageously shifts the emitter work function. Alongside augmentation of the nominal crystallite size of the graphitic superstructure, surface bound species are believed to play a key role in the enhanced emission. The hydrogen plasma treatment was also noted to increase the emission spatial uniformity, with an approximate four times reduction in the per unit area variation in emission current density. Our findings suggest that plasma treatments, and particularly hydrogen and hydrogen-containing precursors, may provide an efficient, simple, and low cost means of realizing enhanced nanocarbon-based field emission devices via the engineered degradation of the nascent lattice, and adjustment of the surface work function. PMID:28066543

  5. Half-lives and branchings for {beta}-delayed neutron emission for neutron-rich Co-Cu isotopes in the r-process

    SciTech Connect

    Hosmer, P.; Estrade, A.; Montes, F.; Ouellette, M.; Pellegrini, E.; Schatz, H.; Aprahamian, A.; Arndt, O.; Pfeiffer, B.; Clement, R. R. C.; Mueller, W. F.; Morton, A. C.; Pereira, J.; Santi, P.; Steiner, M.; Stolz, A.; Farouqi, K.; Kratz, K.-L.; Liddick, S. N.; Mantica, P. F.

    2010-08-15

    The {beta} decays of very neutron-rich nuclides in the Co-Zn region were studied experimentally at the National Superconducting Cyclotron Laboratory using the NSCL {beta}-counting station in conjunction with the neutron detector NERO. We measured the branchings for {beta}-delayed neutron emission (P{sub n} values) for {sup 74}Co (18{+-}15%) and {sup 75-77}Ni (10{+-}2.8%, 14{+-}3.6%, and 30{+-}24%, respectively) for the first time, and remeasured the P{sub n} values of {sup 77-79}Cu, {sup 79,81}Zn, and {sup 82}Ga. For {sup 77-79}Cu and for {sup 81}Zn we obtain significantly larger P{sub n} values compared to previous work. While the new half-lives for the Ni isotopes from this experiment had been reported before, we present here in addition the first half-life measurements of {sup 75}Co (30{+-}11 ms) and {sup 80}Cu (170{sub -50}{sup +110} ms). Our results are compared with theoretical predictions, and their impact on various types of models for the astrophysical rapid neutron-capture process (r-process) is explored. We find that with our new data, the classical r-process model is better able to reproduce the A=78-80 abundance pattern inferred from the solar abundances. The new data also influence r-process models based on the neutrino-driven high-entropy winds in core collapse supernovae.

  6. Proton Therapy Verification with PET Imaging

    PubMed Central

    Zhu, Xuping; Fakhri, Georges El

    2013-01-01

    Proton therapy is very sensitive to uncertainties introduced during treatment planning and dose delivery. PET imaging of proton induced positron emitter distributions is the only practical approach for in vivo, in situ verification of proton therapy. This article reviews the current status of proton therapy verification with PET imaging. The different data detecting systems (in-beam, in-room and off-line PET), calculation methods for the prediction of proton induced PET activity distributions, and approaches for data evaluation are discussed. PMID:24312147

  7. Diamondoid monolayers as electron emitters

    DOEpatents

    Yang, Wanli; Fabbri, Jason D.; Melosh, Nicholas A.; Hussain, Zahid; Shen, Zhi-Xun

    2013-10-29

    Provided are electron emitters based upon diamondoid monolayers, preferably self-assembled higher diamondoid monolayers. High intensity electron emission has been demonstrated employing such diamondoid monolayers, particularly when the monolayers are comprised of higher diamondoids. The application of such diamondoid monolayers can alter the band structure of substrates, as well as emit monochromatic electrons, and the high intensity electron emissions can also greatly improve the efficiency of field-effect electron emitters as applied to industrial and commercial applications.

  8. Diamondoid monolayers as electron emitters

    DOEpatents

    Yang, Wanli [El Cerrito, CA; Fabbri, Jason D [San Francisco, CA; Melosh, Nicholas A [Menlo Park, CA; Hussain, Zahid [Orinda, CA; Shen, Zhi-Xun [Stanford, CA

    2012-04-10

    Provided are electron emitters based upon diamondoid monolayers, preferably self-assembled higher diamondoid monolayers. High intensity electron emission has been demonstrated employing such diamondoid monolayers, particularly when the monolayers are comprised of higher diamondoids. The application of such diamondoid monolayers can alter the band structure of substrates, as well as emit monochromatic electrons, and the high intensity electron emissions can also greatly improve the efficiency of field-effect electron emitters as applied to industrial and commercial applications.

  9. Visible Spectrum Incandescent Selective Emitter

    SciTech Connect

    Sonsight Inc.

    2004-04-30

    The purpose of the work performed was to demonstrate the feasibility of a novel bi-layer selective emitter. Selective emitters are incandescent radiant bodies with emissivities that are substantially larger in a selected part of the radiation spectrum, thereby significantly shifting their radiated spectral distribution from that of a blackbody radiating at the same temperature. The major research objectives involved answering the following questions: (1) What maximum VIS/NIR radiant power and emissivity ratios can be attained at 2650 K? (2) What is the observed emitter body life and how does its performance vary with time? (3) What are the design tradeoffs for a dual heating approach in which both an internally mounted heating coil and electrical resistance self-heating are used? (4) What are the quantitative improvements to be had from utilizing a bi-layer emitter body with a low emissivity inner layer and a partially transmissive outer layer? Two approaches to obtaining selective emissivity were investigated. The first was to utilize large optical scattering within an emitter material with a spectral optical absorption that is much greater within the visible spectrum than that within the NIR. With this approach, an optically thick emitter can radiate almost as if optically thin because essentially, scattering limits the distance below the surface from which significant amounts of internally generated radiation can emerge. The performance of thin emitters was also investigated (for optically thin emitters, spectral emissivity is proportional to spectral absorptivity). These emitters were fabricated from thin mono-layer emitter rods as well as from bi-layer rods with a thin emitter layer mounted on a substrate core. With an initially estimated energy efficiency of almost three times that of standard incandescent bulbs, a number of energy, economic and environmental benefits such as less energy use and cost, reduced CO{sub 2} emissions, and no mercury contamination

  10. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1990-01-01

    A support is provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  11. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1990-01-01

    A support is provided for use in a thermionic converter to support an end an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housng, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  12. Combustion powered thermophotovoltaic emitter system

    SciTech Connect

    McHenry, R.S.

    1995-07-01

    The US Naval Academy (USNA) has recently completed an engineering design project for a high temperature thermophotovoltaic (TPV) photon emitter. The final apparatus was to be portable, completely self contained, and was to incorporate cycle efficiency optimization such as exhaust stream recuperation. Through computer modeling and prototype experimentation, a methane fueled emitter system was designed from structural ceramic materials to fulfill the high temperature requirements necessary for high system efficiency. This paper outlines the engineering design process, discusses obstacles and solutions encountered, and presents the final design.

  13. Emitter location errors in electronic recognition system

    NASA Astrophysics Data System (ADS)

    Matuszewski, Jan; Dikta, Anna

    2017-04-01

    The paper describes some of the problems associated with emitter location calculations. This aspect is the most important part of the series of tasks in the electronic recognition systems. The basic tasks include: detection of emission of electromagnetic signals, tracking (determining the direction of emitter sources), signal analysis in order to classify different emitter types and the identification of the sources of emission of the same type. The paper presents a brief description of the main methods of emitter localization and the basic mathematical formulae for calculating their location. The errors' estimation has been made to determine the emitter location for three different methods and different scenarios of emitters and direction finding (DF) sensors deployment in the electromagnetic environment. The emitter has been established using a special computer program. On the basis of extensive numerical calculations, the evaluation of precise emitter location in the recognition systems for different configuration alignment of bearing devices and emitter was conducted. The calculations which have been made based on the simulated data for different methods of location are presented in the figures and respective tables. The obtained results demonstrate that calculation of the precise emitter location depends on: the number of DF sensors, the distances between emitter and DF sensors, their mutual location in the reconnaissance area and bearing errors. The precise emitter location varies depending on the number of obtained bearings. The higher the number of bearings, the better the accuracy of calculated emitter location in spite of relatively high bearing errors for each DF sensor.

  14. Transverse RMS emittance evaluation based upon explicit and reasonable definitions of 100% and 95% beams

    NASA Astrophysics Data System (ADS)

    Ueno, A.; Ohkoshi, K.; Ikegami, K.; Takagi, A.; Oguri, H.

    2017-08-01

    In order to compare brightnesses of beams produced by different ion sources, a transverse emittance evaluation procedure with consistency and small ambiguity for different background noises is required. The procedure to evaluate emittances of beams produced by the Japan Proton Accelerator Research Complex (J-PARC) cesiated RF-driven Hˉ ion source is presented in this paper. The ambiguity in emittance evaluations is eliminated by defining uniquely 100% and 95% beams with a reasonably corrected beam-signal base-level. Two 95%-beam transverse normalized root mean square emittances of beams, which are produced with almost the same 2-MHz RF power and cesiation condition but with different background noise, are estimated as almost the same values by this procedure.

  15. The decay of proton-rich nuclei in the mass A = 36 56 region

    SciTech Connect

    Dossat, C.; Aksouh, F.; Becker, F.; Bey, A.; Borcea, C.; Borcea, R.; Boston, A.; Caamano, M.; Canchel, G.; Czajkowski, S.; de Oliveira Santos, F.; Fleury, A.; Giovinazzo, J.; Grzywacz, Robert Kazimierz; Hellstrom, M.; Honma, M.; Janas, Z.; Karamanis, D.; Lewitowicz, M.; Lopez Jimenez, M. J.; Matea, I.; Maslov, V.; Mayet, P.; Moore, C.; Pfutzner, M.; Pravikoff, M. S.; Stefan, I.; Thomas, J.-C.

    2007-01-01

    In a series of experiments at the SISSI/LISE3 facility of GANIL conducted between 1999 and 2004, we have collected decay information for proton-rich nuclei between {sup 36}Ca and {sup 56}Zn. The data allowed us to study the decay properties of 26 nuclei. The main experimental information obtained for all nuclei is their {beta}-decay half-life and their total {beta}-delayed proton emission branching ratio. For many nuclei, individual proton groups and {gamma} rays were identified and allowed us to establish first partial decay schemes for some of the nuclei studied. In addition, mass-excess values have been determined for some of the nuclei by means of the isobaric multiplet mass equation. For {sup 50}Ni, the decay via {beta}-delayed two-proton emission could be tentatively identified. The decay of {sup 49}Ni allowed for the first time to identify the first 2{sup +} state in {sup 48}Fe. The experimental data are confronted to model predictions for the half-life and the mass-excess values.

  16. Shielding in ungated field emitter arrays

    SciTech Connect

    Harris, J. R.; Jensen, K. L.; Shiffler, D. A.; Petillo, J. J.

    2015-05-18

    Cathodes consisting of arrays of high aspect ratio field emitters are of great interest as sources of electron beams for vacuum electronic devices. The desire for high currents and current densities drives the cathode designer towards a denser array, but for ungated emitters, denser arrays also lead to increased shielding, in which the field enhancement factor β of each emitter is reduced due to the presence of the other emitters in the array. To facilitate the study of these arrays, we have developed a method for modeling high aspect ratio emitters using tapered dipole line charges. This method can be used to investigate proximity effects from similar emitters an arbitrary distance away and is much less computationally demanding than competing simulation approaches. Here, we introduce this method and use it to study shielding as a function of array geometry. Emitters with aspect ratios of 10{sup 2}–10{sup 4} are modeled, and the shielding-induced reduction in β is considered as a function of tip-to-tip spacing for emitter pairs and for large arrays with triangular and square unit cells. Shielding is found to be negligible when the emitter spacing is greater than the emitter height for the two-emitter array, or about 2.5 times the emitter height in the large arrays, in agreement with previously published results. Because the onset of shielding occurs at virtually the same emitter spacing in the square and triangular arrays, the triangular array is preferred for its higher emitter density at a given emitter spacing. The primary contribution to shielding in large arrays is found to come from emitters within a distance of three times the unit cell spacing for both square and triangular arrays.

  17. Ultra Low Emittance Light Sources

    SciTech Connect

    Bengtsson,J.

    2008-06-23

    This paper outlines the special issues for reaching sub-nm emittance in a storage ring. Effects of damping wigglers, intra-beam scattering and lifetime issues, dynamic aperture optimization, control of optics, and their interrelations are covered in some detail. The unique choices for the NSLS-II are given as one example.

  18. Proton synchrotron radiation at Fermilab

    SciTech Connect

    Thurman-Keup, Randy; /Fermilab

    2006-05-01

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

  19. Mass Determination of Two-Proton Radioactive Nuclides

    SciTech Connect

    Miernik, Krzysztof A

    2012-01-01

    The masses of heavy two-proton emitters (45Fe, 48Ni and 54Zn) are calculated, basing on experimentally measured two-proton decay energies. The results are compared with theoretical predictions and extrapolations.

  20. Compact measurement station for low energy proton beams

    NASA Astrophysics Data System (ADS)

    Yildiz, H.; Ozbey, A.; Oz, S.; Yasatekin, B.; Turemen, G.; Ogur, S.; Sunar, E.; Aydin, Y. O.; Dimov, V. A.; Unel, G.; Alacakir, A.

    2017-02-01

    A compact, remote controlled, cost efficient diagnostic station has been developed to measure the charge, the profile and the emittance for low energy proton beams. It has been installed and tested in the proton beam line of the Project Prometheus at SANAEM of the Turkish Atomic Energy Authority.

  1. Automatic emittance measurement at the ATF

    SciTech Connect

    Wang, X.J.; Malone, R.; Batchelor, K.; Ben-Zvi, I.

    1993-07-01

    An automatic emittance measurement system to characterize the transverse emittance of the electron beam produced by the BNL photocathode electron gun is described. The system utilize a VAX workstation and a Spiricon beam analyzer. A operator window (created through the Vista control software package) controls the emittance measurement system and the graphic presentation of the results. Quadrupole variation method is used for the ATF automatic emittance measurement system. A simple emittance formula was derived to study the performance of the quadrupole variation method, and compared with the ATF experimental data is also presented.

  2. Carbon nanotubes as field emitter.

    PubMed

    Zou, Rujia; Hu, Junqing; Song, Yuelin; Wang, Na; Chen, Huihui; Chen, Haihua; Wu, Jianghong; Sun, Yangang; Chen, Zhigang

    2010-12-01

    Carbon nanotubes (CNTs) have recently emerged as a promising material of electron field emitters. They exhibit extraordinary field emission properties because of their high electrical conductivity, high aspect ratio "needle like" shape for optimum geometrical field enhancement, and remarkable thermal stability. In this Review, we emphasize the estimation and influencing factors of CNTs' emission properties, and discuss in detail the emission properties of macroscopic CNT cathodes, especially fabricated by transplant methods, and describe recent progress on understanding of CNT field emitters and analyze issues related to applications of CNT based cold cathodes in field emission display (FED). We foresee that CNT-FED will take an important place in display technologies in the near future.

  3. Science and applications of low-emittance electron beams

    SciTech Connect

    van Bibber, K

    2000-08-20

    The capability of making very low-emittance electron beams of temporally short, high charge bunches has opened up exciting new possibilities in basic and applied science. Two notable applications are high energy electron-positron linear colliders for particle physics, and fourth-generation light sources consisting of linac-driven Free-Electron Lasers (FEL), both of which represent significant programmatic potential for the Laboratory in the future. The technologies contributing to low-emittance electron beams and their applications, namely precision fabrication, ultra-short pulse lasers, and RF photocathode injectors, are all areas of Lab expertise, and the work carried out under this LDRD project further expanded our core-competency in advanced concept accelerators. Furthermore, high energy accelerators have become a cornerstone of the SBSS program, as illustrated by the recent development of proton radiography as a prime technology candidate for the Advanced Hydrotest Facility (AHF), which enhanced the significance of this project all the more. This was a one-year project to both advance the technology of, and participate in the science enabled by very low-emittance electron beams. The work centered around the two themes above, namely electron-positron linear colliders, and the new fourth-generation light sources. This work built upon previous LDRD investments, and was intended to emphasize accelerator physics experiments.

  4. Metal halide perovskite light emitters

    PubMed Central

    Kim, Young-Hoon; Cho, Himchan; Lee, Tae-Woo

    2016-01-01

    Twenty years after layer-type metal halide perovskites were successfully developed, 3D metal halide perovskites (shortly, perovskites) were recently rediscovered and are attracting multidisciplinary interest from physicists, chemists, and material engineers. Perovskites have a crystal structure composed of five atoms per unit cell (ABX3) with cation A positioned at a corner, metal cation B at the center, and halide anion X at the center of six planes and unique optoelectronic properties determined by the crystal structure. Because of very narrow spectra (full width at half-maximum ≤20 nm), which are insensitive to the crystallite/grain/particle dimension and wide wavelength range (400 nm ≤ λ ≤ 780 nm), perovskites are expected to be promising high-color purity light emitters that overcome inherent problems of conventional organic and inorganic quantum dot emitters. Within the last 2 y, perovskites have already demonstrated their great potential in light-emitting diodes by showing high electroluminescence efficiency comparable to those of organic and quantum dot light-emitting diodes. This article reviews the progress of perovskite emitters in two directions of bulk perovskite polycrystalline films and perovskite nanoparticles, describes current challenges, and suggests future research directions for researchers to encourage them to collaborate and to make a synergetic effect in this rapidly emerging multidisciplinary field. PMID:27679844

  5. Alpha particle emitters in medicine

    SciTech Connect

    Fisher, D.R.

    1989-09-01

    Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 ({sup 211}At) and natural bismuth-212 ({sup 212}Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 ({sup 223}Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs.

  6. Transverse Emittance Reduction with Tapered Foil

    SciTech Connect

    Jiao, Yi; Chao, Alex; Cai, Yunhai; /SLAC

    2011-12-09

    The idea of reducing transverse emittance with tapered energy-loss foil is proposed by J.M. Peterson in 1980s and recently by B. Carlsten. In this paper, we present the physical model of tapered energy-loss foil and analyze the emittance reduction using the concept of eigen emittance. The study shows that, to reduce transverse emittance, one should collimate at least 4% of particles which has either much low energy or large transverse divergence. The multiple coulomb scattering is not trivial, leading to a limited emittance reduction ratio. Small transverse emittances are of essential importance for the accelerator facilities generating free electron lasers, especially in hard X-ray region. The idea of reducing transverse emittance with tapered energy-loss foil is recently proposed by B. Carlsten [1], and can be traced back to J.M. Peterson's work in 1980s [2]. Peterson illustrated that a transverse energy gradient can be produced with a tapered energy-loss foil which in turn leads to transverse emittance reduction, and also analyzed the emittance growth from the associated multiple coulomb scattering. However, what Peterson proposed was rather a conceptual than a practical design. In this paper, we build a more complete physical model of the tapered foil based on Ref. [2], including the analysis of the transverse emittance reduction using the concept of eigen emittance and confirming the results by various numerical simulations. The eigen emittance equals to the projected emittance when there is no cross correlation in beam's second order moments matrix [3]. To calculate the eigen emittances, it requires only to know the beam distribution at the foil exit. Thus, the analysis of emittance reduction and the optics design of the subsequent beam line section can be separated. In addition, we can combine the effects of multiple coulomb scattering and transverse energy gradient together in the beam matrix and analyze their net effect. We find that,when applied to an

  7. Development of a 110-m-mA, 75-keV proton injector for high-current, CW linacs

    SciTech Connect

    Sherman, J.D.; Bolme, G.O.; Hansborough, L.D.

    1996-09-01

    A dc proton injector is being developed for a 6.7 MeV CW RFQ at Los Alamos. The RFQ input beam requirements are 75 keV energy, 110 mA dc proton current, and 0.20 {pi}mm-mrad rms normalized emittance. The injector has now produced a 75-keV, 117-mA dc proton beam (130 mA total current) with the required emittance. The emittance has been measured after a 2.1 m long two-solenoid beam transport system. The measured emittance can be explained in terms of the ion source emittance and beam transport through the focusing elements. Measured proton fractions are 90-92% of the beam current. Engineering of the accelerating column high-voltage design is being improved to increase the injector reliability. Injector design details and status are presented.

  8. EMITTANCE CONTROL FOR VERY SHORT BUNCHES

    SciTech Connect

    Bane, K

    2004-07-20

    Many recent accelerator projects call for the production of high energy bunches of electrons or positrons that are simultaneously short, intense, and have small emittances. Examples of such projects are the Self-Amplified Spontaneous Emission (SASE) FEL's, such as the Linac Coherent Light Source (LCLS). A major challenge is keeping in check forces that increase beam emittances in accelerator components, such as: wakefields of accelerator structures and surface roughness, and coherent synchrotron radiation. We describe such forces and discuss emittance control.

  9. Emittance Growth in the NLCTA First Chicane

    SciTech Connect

    Sun, Yipeng; Adolphsen, Chris; /SLAC

    2011-08-19

    In this paper, the emittance growth in the NLCTA (Next Linear Collider Test Accelerator) first chicane region is evaluated by simulation studies. It is demonstrated that the higher order fields of the chicane dipole magnet and the dipole corrector magnet (which is attached on the quadrupoles) are the main contributions for the emittance growth, especially for the case with a large initial emittance ({gamma}{epsilon}{sub 0} = 5 {micro}m for instance). These simulation results agree with the experimental observations.

  10. Minimum emittance in TBA and MBA lattices

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Peng, Yue-Mei

    2015-03-01

    For reaching a small emittance in a modern light source, triple bend achromats (TBA), theoretical minimum emittance (TME) and even multiple bend achromats (MBA) have been considered. This paper derived the necessary condition for achieving minimum emittance in TBA and MBA theoretically, where the bending angle of inner dipoles has a factor of 31/3 bigger than that of the outer dipoles. Here, we also calculated the conditions attaining the minimum emittance of TBA related to phase advance in some special cases with a pure mathematics method. These results may give some directions on lattice design.

  11. An ESS system for ECRIS Emittance Research

    SciTech Connect

    Cao, Y.; Sun, L.T.; He, W.; Ma, L.; Zhang, Z.M.; Zhao, H.Y.; Zhao, H.W.; Zhang, X.Z.; Guo, X.H.; Ma, B.H.; Li, J.; Wang, H.; Li, J.Y.; Li, X.X.; Feng, Y.C.; Lu, W.

    2005-03-15

    An emittance scanner named Electric-Sweep Scanner had been designed and fabricated in IMP. And it has been set up on the LECR3 beam line for the ion beam quality study. With some development, the ESS system has become a relatively dependable and reliable emittance scanner. Its experiment error is about 10 percent. We have done a lot of experiments of emittance measurement on LECR3 ion source, and have researched the relations between ion beam emittance and the major parameters of ECR ion source. The reliability and accuracy test results are presented in this paper. And the performance analysis is also discussed.

  12. Hybrid emitter all back contact solar cell

    DOEpatents

    Loscutoff, Paul; Rim, Seung

    2016-04-12

    An all back contact solar cell has a hybrid emitter design. The solar cell has a thin dielectric layer formed on a backside surface of a single crystalline silicon substrate. One emitter of the solar cell is made of doped polycrystalline silicon that is formed on the thin dielectric layer. The other emitter of the solar cell is formed in the single crystalline silicon substrate and is made of doped single crystalline silicon. The solar cell includes contact holes that allow metal contacts to connect to corresponding emitters.

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

    SciTech Connect

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

    2008-07-15

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

  14. Chemical regeneration of emitter surface increases thermionic diode life

    NASA Technical Reports Server (NTRS)

    Breiteieser, R.

    1966-01-01

    Chemical regeneration of sublimated emitter electrode increases the operating efficiency and life of thermionic diodes. A gas which forms chemical compounds with the sublimated emitter material is introduced into the space between the emitter and the collector. The compounds migrate to the emitter where they decompose and redeposit the emitter material.

  15. Decay spectroscopy for nuclear astrophysics: β- and β-delayed proton decay

    NASA Astrophysics Data System (ADS)

    Trache, L.; Banu, A.; Hardy, J. C.; Iacob, V. E.; McCleskey, M.; Roeder, B. T.; Simmons, E.; Spiridon, A.; Tribble, R. E.; Saastamoinen, A.; Jokinen, A.; Äysto, J.; Davinson, T.; Lotay, G.; Woods, P. J.; Pollacco, E.

    2012-02-01

    In several radiative proton capture reactions important in novae and XRBs, the resonant parts play the capital role. We use decay spectroscopy techniques to find these resonances and study their properties. We have developed techniques to measure beta- and beta-delayed proton decay of sd-shell, proton-rich nuclei produced and separated with the MARS recoil spectrometer of Texas A&M University. The short-lived radioactive species are produced in-flight, separated, then slowed down (from about 40 MeV/u) and implanted in the middle of very thin Si detectors. This allows us to measure protons with energies as low as 200 keV from nuclei with lifetimes of 100 ms or less. At the same time we measure gamma-rays up to 8 MeV with high resolution HPGe detectors. We have studied the decay of 23Al, 27P, 31Cl, all important for understanding explosive H-burning in novae. The technique has shown a remarkable selectivity to beta-delayed charged-particle emission and works even at radioactive beam rates of a few pps. The states populated are resonances for the radiative proton capture reactions 22Na(p,γ)23Mg (crucial for the depletion of 22Na in novae), 26mAl(p,γ)27Si and 30P(p,γ)31S (bottleneck in novae and XRB burning), respectively. Lastly, results with a new detector that allowed us to measure down to about 80 keV proton energy are announced.

  16. Comments on Injector Proton Beam Study in Run 2014

    SciTech Connect

    Zhang, S. Y.

    2014-09-15

    During the entire period of injector proton study in run 2014, it seems that the beam transverse emittance out of Booster is larger than that in run 2013. The emittance measured at the BtA transfer line and also the transmission from Booster late to AGS late are presented for this argument. In addition to this problem, it seems that the multiturn Booster injection, which defines the transverse emittance, needs more attention. Moreover, for high intensity operations, the space charge effect may be already relevant in RHIC polarized proton runs. With the RHIC proton intensity improvement in the next several years, higher Booster input intensity is needed, therefore, the space charge effect at the Booster injection and early ramp may become a new limiting factor.

  17. Selective Emitter Pumped Rare Earth Laser

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor); Patton, Martin O. (Inventor)

    2001-01-01

    A selective emitter pumped rare earth laser provides an additional type of laser for use in many laser applications. Rare earth doped lasers exist which are pumped with flashtubes or laser diodes. The invention uses a rare earth emitter to transform thermal energy input to a spectral band matching the absorption band of a rare earth in the laser in order to produce lasing.

  18. Emittance growth in rippled solenoidal magnetic fields

    SciTech Connect

    Adler, R.J.

    1987-01-01

    Emittance growth results due to accelerating gaps, and magnetic field gaps in induction accelerators. The analytic technique previously used to study electric field induced emittance growth for immersed source beams is extended to include solenoid fringing field effects in the present work. These results have application to industrial induction accelerators and to high brightness Free Electron Laser drivers. 1 ref., 2 figs.

  19. Negative Ion Beam Extraction and Emittance

    SciTech Connect

    Holmes, Andrew J. T.

    2007-08-10

    The use of magnetic fields to both aid the production of negative ions and suppress the co-extracted electrons causes the emittance and hence the divergence of the negative ion beam to increase significantly due to the plasma non-uniformity from jxB drift. This drift distorts the beam-plasma meniscus and experimental results of the beam emittance are presented, which show that non-uniformity causes the square of the emittance to be proportional to the 2/3 power of the extracted current density. This can cause the divergence of the negative ion beam to be significantly larger than its positive ion counterpart. By comparing results from positive and negative ion beam emittances from the same source, it is also possible to draw conclusions about their vulnerability to magnetic effects. Finally emittances of caesiated and un-caesiated negative ion beams are compared to show how the surface and volume modes of production interact.

  20. Directional emittance surface measurement system and process

    NASA Technical Reports Server (NTRS)

    Puram, Chith K. (Inventor); Daryabeigi, Kamran (Inventor); Wright, Robert (Inventor); Alderfer, David W. (Inventor)

    1994-01-01

    Apparatus and process for measuring the variation of directional emittance of surfaces at various temperatures using a radiometric infrared imaging system. A surface test sample is coated onto a copper target plate provided with selective heating within the desired incremental temperature range to be tested and positioned onto a precision rotator to present selected inclination angles of the sample relative to the fixed positioned and optically aligned infrared imager. A thermal insulator holder maintains the target plate on the precision rotator. A screen display of the temperature obtained by the infrared imager, and inclination readings are provided with computer calculations of directional emittance being performed automatically according to equations provided to convert selected incremental target temperatures and inclination angles to relative target directional emittance values. The directional emittance of flat black lacquer and an epoxy resin measurements obtained are in agreement with the predictions of the electromagnetic theory and with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

  1. New approach to obtain boron selective emitters

    SciTech Connect

    Moehlecke, A.; Luque, A.

    1994-12-31

    Selective emitters, used in high efficiency solar cells, need a series of oxidations and photolithographic steps that render the process more expensive. In this paper, a new way to make selective emitters using boron is presented. The main feature of this approach is to save oxide growths and photolithographic processes and it is based on the property of boron doped silicon surfaces to be resistant to anisotropic etchings like the one performed during the texturization. Using this characteristic of boron emitter surfaces, the authors can obtain a highly doped emitter under metal grid and simultaneously a shield to avoid texture on these surfaces. First cells were processed and short wavelength response of p{sup +}nn{sup +} solar cells was enhanced by using lightly doped boron emitters in the uncovered area.

  2. TPV Systems with Solar Powered Tungsten Emitters

    SciTech Connect

    Vlasov, A. S.; Khvostikov, V. P.; Khvostikova, O. A.; Gazaryan, P. Y.; Sorokina, S. V.; Andreev, V. M.

    2007-02-22

    A solar TPV generator development and characterization are presented. A double stage sunlight concentrator ensures 4600x concentration ratio. TPV modules based on tungsten emitters and GaSb cells were designed, fabricated and tested at indoor and outdoor conditions. The performance of tungsten emitter under concentrated solar radiation was analyzed. Emitter temperatures in the range of 1400-2000 K were measured, depending on the emitter size. The light distribution in the module has been characterized, 1x1 cm GaSb TPV cells were fabricated with the use of the Zn-diffusion and LPE technologies. The cell efficiency of 19% under illumination by a tungsten emitter (27% under spectra cut-off at {lambda} > 1820 nm) heated up to 1900-2000 K had been derived from experimentally measured PV parameters. The series connection of PV cells was ensured by the use of BeO ceramics. The possibilities of system performance improvement are discussed.

  3. Emittance measurements of the CLIO electron beam

    NASA Astrophysics Data System (ADS)

    Chaput, R.; Devanz, G.; Joly, P.; Kergosien, B.; Lesrel, J.

    1997-02-01

    We have designed a setup to measure the transverse emittance at the CLIO accelerator exit, based on the "3 gradients" method. The beam transverse size is measured simply by scanning it with a steering coil across a fixed jaw and recording the transmitted current, at various quadrupole strengths. A code then performs a complete calculation of the emittance using the transfer matrix of the quadrupole instead of the usual classical lens approximation. We have studied the influence of various parameters on the emittance: Magnetic field on the e-gun and the peak current. We have also improved a little the emittance by replacing a mismatched pipe between the buncher and accelerating section to avoid wake-field effects; The resulting improvements of the emittance have led to an increase in the FEL emitted power.

  4. Proton Therapy

    MedlinePlus

    ... Proton Therapy Alternative & Integrative Medicine Clinical Trials GBM AGILE TTFields – Optune™ Brain Tumor Treatment Locations Treatment Side ... Proton Therapy Alternative & Integrative Medicine Clinical Trials GBM AGILE TTFields – Optune™ Brain Tumor Treatment Locations Treatment Side ...

  5. Enantioselective Protonation

    PubMed Central

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

    2010-01-01

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

  6. Positron emitter labeled enzyme inhibitors

    DOEpatents

    Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

    1987-05-22

    This invention involved a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide in activators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography. 2 figs.

  7. Positron emitter labeled enzyme inhibitors

    DOEpatents

    Fowler, Joanna S.; MacGregor, Robert R.; Wolf, Alfred P.; Langstrom, Bengt

    1990-01-01

    This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.

  8. Positron emitter labeled enzyme inhibitors

    SciTech Connect

    Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.; Langstrom, B.

    1990-04-03

    This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.

  9. Microlensless interdigitated photoconductive terahertz emitters.

    PubMed

    Singh, Abhishek; Prabhu, S S

    2015-01-26

    We report here fabrication of interdigitated photoconductive antenna (iPCA) terahertz (THz) emitters based on plasmonic electrode design. Novel design of this iPCA enables it to work without microlens array focusing, which is otherwise required for photo excitation of selective photoconductive regions to avoid the destructive interference of emitted THz radiation from oppositely biased regions. Benefit of iPCA over single active region PCA is, photo excitation can be done at larger area hence avoiding the saturation effect at higher optical excitation density. The emitted THz radiation power from plasmonic-iPCAs is ~2 times more than the single active region plasmonic PCA at 200 mW optical excitation, which will further increase at higher optical powers. This design is expected to reduce fabrication cost of photoconductive THz sources and detectors.

  10. Low Emittance Electron Beam Studies

    SciTech Connect

    Tikhoplav, Rodion

    2006-01-01

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

  11. Portable infrared reflectometer for evaluating emittance

    NASA Astrophysics Data System (ADS)

    Jaworske, Donald A.; Skowronski, Timothy J.

    2000-01-01

    Optical methods are frequently used to evaluate the emittance of candidate spacecraft thermal control materials. One new optical method utilizes a portable infrared reflectometer capable of obtaining spectral reflectance of an opaque surface in the range of 2 to 25 microns using a Michelson-Type FTIR interferometer. This miniature interferometer collects many infrared spectra over a short period of time. It also allows the size of the instrument to be small such that spectra can be collected in the laboratory or in the field. Infrared spectra are averaged and integrated with respect to the room temperature black body spectrum to yield emittance at 300 K. Integrating with respect to other black body spectra yields emittance values at other temperatures. Absorption bands in the spectra may also be used for chemical species identification. The emittance of several samples was evaluated using this portable infrared reflectometer, an old infrared reflectometer equipped with dual rotating black body cavities, and a bench top thermal vacuum chamber. Samples for evaluation were purposely selected such that a range of emittance values and thermal control material types would be represented, including polished aluminum, Kapton®, silvered Teflon®, and the inorganic paint Z-93-P. Results indicate an excellent linear relationship between the room temperature emittance calculated from infrared spectral data and the emittance obtained from the dual rotating black body cavities and thermal vacuum chamber. The prospect of using the infrared spectral data for chemical species identification will also be discussed. .

  12. The preservation of low emittance flat beams

    SciTech Connect

    Raubenheimer, T.O.

    1993-04-01

    Many future linear collider designs require beams with very small transverse emittances and large emittance ratios {epsilon}{sub x} {much_gt} {epsilon}{sub y}. In this paper, we will discuss issues associated with the preservation of these small emittances during the acceleration of the beams. The primary sources of transverse emittance dilution in a high energy linear accelerator are the transverse wakefields, the dispersive errors, RF deflections, and betatron coupling. We will discuss the estimation of these effects and the calculation of tolerances that will limit the emittance dilution with a high degree of confidence. Since the six-dimensional emittance is conserved and only the projected emittances are increased, these dilutions can be corrected if the beam has not filamented (phase mixed). We discuss methods of correcting the dilutions and easing the tolerances with beam-based alignment and steering techniques, and non-local trajectory bumps. Finally, we discuss another important source of luminosity degradation, namely, pulse-to-pulse jitter.

  13. Multinozzle Emitter Arrays for Nanoelectrospray Mass Spectrometry

    PubMed Central

    Mao, Pan; Wang, Hung-Ta; Yang, Peidong; Wang, Daojing

    2011-01-01

    Mass spectrometry (MS) is the enabling technology for proteomics and metabolomics. However, dramatic improvements in both sensitivity and throughput are still required to achieve routine MS-based single cell proteomics and metabolomics. Here, we report the silicon-based monolithic multinozzle emitter array (MEA), and demonstrate its proof-of-principle applications in high-sensitivity and high-throughput nanoelectrospray mass spectrometry. Our MEA consists of 96 identical 10-nozzle emitters in a circular array on a 3-inch silicon chip. The geometry and configuration of the emitters, the dimension and number of the nozzles, and the micropillar arrays embedded in the main channel, can be systematically and precisely controlled during the microfabrication process. Combining electrostatic simulation and experimental testing, we demonstrated that sharpened-end geometry at the stem of the individual multinozzle emitter significantly enhanced the electric fields at its protruding nozzle tips, enabling sequential nanoelectrospray for the high-density emitter array. We showed that electrospray current of the multinozzle emitter at a given total flow rate was approximately proportional to the square root of the number of its spraying-nozzles, suggesting the capability of high MS sensitivity for multinozzle emitters. Using a conventional Z-spray mass spectrometer, we demonstrated reproducible MS detection of peptides and proteins for serial MEA emitters, achieving sensitivity and stability comparable to the commercial capillary emitters. Our robust silicon-based MEA chip opens up the possibility of a fully-integrated microfluidic system for ultrahigh-sensitivity and ultrahigh-throughput proteomics and metabolomics. PMID:21728281

  14. Multinozzle Emitter Arrays for Nanoelectrospray Mass Spectrometry

    SciTech Connect

    Mao, Pan; Wang, Hung-Ta; Yang, Peidong; Wang, Daojing

    2011-06-16

    Mass spectrometry (MS) is the enabling technology for proteomics and metabolomics. However, dramatic improvements in both sensitivity and throughput are still required to achieve routine MS-based single cell proteomics and metabolomics. Here, we report the silicon-based monolithic multinozzle emitter array (MEA), and demonstrate its proof-of-principle applications in high-sensitivity and high-throughput nanoelectrospray mass spectrometry. Our MEA consists of 96 identical 10-nozzle emitters in a circular array on a 3-inch silicon chip. The geometry and configuration of the emitters, the dimension and number of the nozzles, and the micropillar arrays embedded in the main channel, can be systematically and precisely controlled during the microfabrication process. Combining electrostatic simulation and experimental testing, we demonstrated that sharpened-end geometry at the stem of the individual multinozzle emitter significantly enhanced the electric fields at its protruding nozzle tips, enabling sequential nanoelectrospray for the high-density emitter array. We showed that electrospray current of the multinozzle emitter at a given total flow rate was approximately proportional to the square root of the number of its spraying-nozzles, suggesting the capability of high MS sensitivity for multinozzle emitters. Using a conventional Z-spray mass spectrometer, we demonstrated reproducible MS detection of peptides and proteins for serial MEA emitters, achieving sensitivity and stability comparable to the commercial capillary emitters. Our robust silicon-based MEA chip opens up the possibility of a fully-integrated microfluidic system for ultrahigh-sensitivity and ultrahigh-throughput proteomics and metabolomics.

  15. Narrowband terahertz emitters using metamaterial films.

    PubMed

    Alves, Fabio; Kearney, Brian; Grbovic, Dragoslav; Karunasiri, Gamani

    2012-09-10

    In this article we report on metamaterial-based narrowband thermal terahertz (THz) emitters with a bandwidth of about 1 THz. Single band emitters designed to radiate in the 4 to 8 THz range were found to emit as high as 36 W/m(2) when operated at 400 °C. Emission into two well-separated THz bands was also demonstrated by using metamaterial structures featuring more complex unit cells. Imaging of heated emitters using a microbolometer camera fitted with THz optics clearly showed the expected higher emissivity from the metamaterial structure compared to low-emissivity of the surrounding aluminum.

  16. Thermophotovoltaic emitter material selection and design

    SciTech Connect

    Saxton, P.C.; Moran, A.L.; Harper, M.J.; Lindler, K.W.

    1997-07-01

    Thermophotovoltaics (TPV) is a potentially attractive direct energy conversion technology. It reduces the need for complex machinery with moving parts and maintenance. TPV generators can be run from a variety of heat sources including waste heat for smaller scale operations. The US Naval Academy`s goal was to build a small experimental thermophotovoltaic generator powered by combustion gases from a General Electric T-58 helicopter gas turbine. The design of the generator imposes material limitations that directly affect emitter and structural materials selection. This paper details emitter material goals and requirements, and the methods used to select suitable candidate emitter materials for further testing.

  17. Online clustering algorithms for radar emitter classification.

    PubMed

    Liu, Jun; Lee, Jim P Y; Senior; Li, Lingjie; Luo, Zhi-Quan; Wong, K Max

    2005-08-01

    Radar emitter classification is a special application of data clustering for classifying unknown radar emitters from received radar pulse samples. The main challenges of this task are the high dimensionality of radar pulse samples, small sample group size, and closely located radar pulse clusters. In this paper, two new online clustering algorithms are developed for radar emitter classification: One is model-based using the Minimum Description Length (MDL) criterion and the other is based on competitive learning. Computational complexity is analyzed for each algorithm and then compared. Simulation results show the superior performance of the model-based algorithm over competitive learning in terms of better classification accuracy, flexibility, and stability.

  18. Proton decay studies at HRIBF

    SciTech Connect

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

    1998-12-21

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

  19. Proton decay studies at HRIBF

    SciTech Connect

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

    1998-12-01

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

  20. Intrinsic emittance reduction in transmission mode photocathodes

    NASA Astrophysics Data System (ADS)

    Lee, Hyeri; Cultrera, Luca; Bazarov, Ivan

    2016-03-01

    High quantum efficiency (QE) and low emittance electron beams provided by multi-alkali photocathodes make them of great interest for next generation high brightness photoinjectors. Spicer's three-step model well describes the photoemission process; however, some photocathode characteristics such as their thickness have not yet been completely exploited to further improve the brightness of the generated electron beams. In this work, we report on the emittance and QE of a multi-alkali photocathode grown onto a glass substrate operated in transmission and reflection modes at different photon energies. We observed a 20% reduction in the intrinsic emittance from the reflection to the transmission mode operation. This observation can be explained by inelastic electron-phonon scattering during electrons' transit towards the cathode surface. Due to this effect, we predict that thicker photocathode layers will further reduce the intrinsic emittance of electron beams generated by photocathodes operated in transmission mode.

  1. Intrinsic emittance reduction in transmission mode photocathodes

    SciTech Connect

    Lee, Hyeri Cultrera, Luca; Bazarov, Ivan

    2016-03-21

    High quantum efficiency (QE) and low emittance electron beams provided by multi-alkali photocathodes make them of great interest for next generation high brightness photoinjectors. Spicer's three-step model well describes the photoemission process; however, some photocathode characteristics such as their thickness have not yet been completely exploited to further improve the brightness of the generated electron beams. In this work, we report on the emittance and QE of a multi-alkali photocathode grown onto a glass substrate operated in transmission and reflection modes at different photon energies. We observed a 20% reduction in the intrinsic emittance from the reflection to the transmission mode operation. This observation can be explained by inelastic electron-phonon scattering during electrons' transit towards the cathode surface. Due to this effect, we predict that thicker photocathode layers will further reduce the intrinsic emittance of electron beams generated by photocathodes operated in transmission mode.

  2. Beam emittance measurements on multicusp ion sources

    NASA Astrophysics Data System (ADS)

    Sarstedt, M.; Lee, Y.; Leung, K. N.; Perkins, L. T.; Pickard, D. S.; Weber, M.; Williams, M. D.

    1996-03-01

    Multicusp ion sources are used for various applications. Presently, the implementation of this type of ion source is planned for the development of an ion beam lithography machine, which will be used for the projection of sub-0.2 μm patterns onto a wafer substrate. Since, for this application, a very good beam quality and a small ion energy spread are required, emittance measurements have been performed on a multicusp ion source for various source conditions. It is shown that the installation of proper capacitors between the extraction electrodes is necessary to avoid rf pickup, which otherwise leads to a distortion of the beam emittance. The influence of the magnetic filter field on the beam emittance has been investigated, and the beam emittance of a dc filament-discharge plasma has also been compared to that of a rf-generated plasma.

  3. Arc-textured high emittance radiator surfaces

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A. (Inventor)

    1991-01-01

    High emittance radiator surfaces are produced by arc-texturing. This process produces such a surface on a metal by scanning it with a low voltage electric arc from a carbon electrode in an inert environment.

  4. Emitters of N-photon bundles.

    PubMed

    Muñoz, C Sánchez; Del Valle, E; Tudela, A González; Müller, K; Lichtmannecker, S; Kaniber, M; Tejedor, C; Finley, J J; Laussy, F P

    2014-07-01

    Controlling the ouput of a light emitter is one of the basic tasks of photonics, with landmarks such as the laser and single-photon sources. The development of quantum applications makes it increasingly important to diversify the available quantum sources. Here, we propose a cavity QED scheme to realize emitters that release their energy in groups, or "bundles" of N photons, for integer N. Close to 100% of two-photon emission and 90% of three-photon emission is shown to be within reach of state of the art samples. The emission can be tuned with system parameters so that the device behaves as a laser or as a N-photon gun. The theoretical formalism to characterize such emitters is developed, with the bundle statistics arising as an extension of the fundamental correlation functions of quantum optics. These emitters will be useful for quantum information processing and for medical applications.

  5. Energy efficiency of electron plasma emitters

    SciTech Connect

    Zalesski, V. G.

    2011-12-15

    Electron emission influence from gas-discharge plasma on plasma emitter energy parameters is considered. It is shown, that electron emission from plasma is accompanied by energy contribution redistribution in the gas-discharge from plasma emitter supplies sources-the gas-discharge power supply and the accelerating voltage power supply. Some modes of electron emission as a result can be realized: 'a probe measurements mode,' 'a transitive mode,' and 'a full switching mode.'.

  6. Enhanced Light Emitters Based on Metamaterials

    DTIC Science & Technology

    2015-03-30

    Enhanced Light Emitters based on Metamaterials We report the development of light emitters based on hyperbolic metamaterials . During the 18 month...layer, use of a high refractive index contrast grating to out-couple light from active hyperbolic metamaterials . We also successfully demonstrated for...the first time simultaneous enhancement in spontaneous emission ad light extraction from active metamaterial structures. The views, opinions and/or

  7. Coaxial inverted geometry transistor having buried emitter

    NASA Technical Reports Server (NTRS)

    Hruby, R. J.; Cress, S. B.; Dunn, W. R. (Inventor)

    1973-01-01

    The invention relates to an inverted geometry transistor wherein the emitter is buried within the substrate. The transistor can be fabricated as a part of a monolithic integrated circuit and is particularly suited for use in applications where it is desired to employ low actuating voltages. The transistor may employ the same doping levels in the collector and emitter, so these connections can be reversed.

  8. Charge neutrality in heavily doped emitters

    SciTech Connect

    del Alamo, J.A.

    1981-09-01

    The applicability of the quasineutrality approximation to modern emitters of solar cells is analytically reviewed. It is shown that this approximation is fulfilled in more than 80% of the depth of a typical solar-cell emitter, being particularly excellent in the heavily doped regions beneath the surface where most of the heavy doping effects arise. Our conclusions are in conflict with Redfield's recent affirmations.

  9. Alpha-emitters for medical therapy workshop

    SciTech Connect

    Feinendegen, L.E.; McClure, J.J.

    1996-12-31

    A workshop on ``Alpha-Emitters for Medical Therapy`` was held May 30-31, 1996 in Denver Colorado to identify research goals and potential clinical needs for applying alpha-particle emitters and to provide DOE with sufficient information for future planning. The workshop was attended by 36 participants representing radiooncology, nuclear medicine, immunotherapy, radiobiology, molecular biology, biochemistry, radiopharmaceutical chemistry, dosimetry, and physics. This report provides a summary of the key points and recommendations arrived at during the conference.

  10. Emittance measurements for optimum operation of the J-PARC RF-driven H{sup −} ion source

    SciTech Connect

    Ueno, A. Ohkoshi, K.; Ikegami, K.; Takagi, A.; Yamazaki, S.; Oguri, H.

    2015-04-08

    In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) second stage requirements of an H{sup −} ion beam of 60mA within normalized emittances of 1.5πmm•mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500μs×25Hz) and a life-time of longer than 1month, the J-PARC cesiated RF-driven H{sup −} ion source was developed by using an internal-antenna developed at the Spallation Neutron Source (SNS). The transverse emittances of the source were measured with various conditions to find out the optimum operation conditions minimizing the horizontal and vertical rms normalized emittances. The transverse emittances were most effectively reduced by operating the source with the plasma electrode temperature lower than 70°C. The optimum value of the cesium (Cs) density around the beam hole of the plasma electrode seems to be proportional to the plasma electrode temperature. The fine control of the Cs density is indispensable, since the emittances seem to increase proportionally to the excessiveness of the Cs density. Furthermore, the source should be operated with the Cs density beyond a threshold value, since the plasma meniscus shape and the ellipse parameters of the transverse emittances seem to be changed step-function-likely on the threshold Cs value.

  11. Low-emittance monoenergetic electron and ion beams from ultra-intense laser-solid interactions

    SciTech Connect

    Cowan, T E; Roth, M; Allen, M M; Johnson, J; Hatchett, S P; Le Sage, G P; Wilks, S C

    2000-03-03

    Recent experiments at the LLNL Petawatt Laser have demonstrated the generation of intense, high energy beams of electrons and ions from the interaction of ultra-intense laser light with solid targets. Focused laser intensities as high as 6 x 10{sup 20} W/cm{sup 2} are achieved, at which point the quiver energies of the target electrons extend to {approx}10 MeV. In this new, fully relativistic regime of laser-plasma interactions, nuclear processes become important and nuclear techniques are required to diagnose the high-energy particle production. In recent experiments we have observed electrons accelerated to 100 MeV, up to 60 MeV brehmsstrahlung generation, photo-nuclear fission and positron-electron pair creation. We also have observed monoenergetic jets of electrons having sufficiently small emittance to be interesting as a laser-accelerated beam, if the production mechanism could be understood and controlled. The huge flux of multi-MeV ponderomotively accelerated electrons produced in the laser-solid interaction is also observed to accelerate contaminant ions from the rear surface of the solid target up to 50 MeV. We describe spectroscopic measurements which reveal intense monoenergetic beam features in the proton energy spectrum. The total spectrum contains >10{sup 13} protons, while the monoenergetic beam pulses contain {approx}1 nC of protons, and exhibits a longitudinal and transverse emittance smaller than conventional RF proton accelerator beams.

  12. Prospects for future proton studies at HRIBF

    NASA Astrophysics Data System (ADS)

    Bingham, C. R.; Batchelder, J. C.; Ginter, T. N.; Gross, C. J.; Grzywacz, R.; Janas, Z.; Karny, M.; McConnell, J. W.; Rykaczewski, K.; Toth, K. S.; Zganjar, E. F.

    2000-05-01

    Great progress has been made in the last 20 years in the study of proton emission from unstable nuclei, but the prospects for additional strides in the next several years are bright. The present main limitations on the study of proton radioactivity are related to the inability to produce copious quantities of nuclides beyond the proton drip line, and the difficulty of measuring proton radioactivity of a mass-separated nucleus in the first few microseconds of its existence. At the Holifield Facility we will attack the second of these limitations by using new signal processing CAMAC modules DGF-4C. Digitizing of the preamplifier signals should enable the analysis of a proton decay occurring at times even less than 1 microsecond after an implant in a strip detector. In the same process, the threshold energy at which we can make measurements will be lowered. These two things will hopefully enable the measurement of lower-energy, but faster decays of isotopes in the 100Sn region and below. For the latter region, the proton decays crucial for a rp-process scenario are of particular interest (e.g. 69Br decay). Secondly, for very short-lived species, we plan to make measurements (without residue separation) at points much closer to the target, thus reducing the flight time between the target and detector. As more intense radioactive beams become available, eg. 56Ni, we will utilize these to produce more neutron-deficient nuclides by use of colder reactions than is possible with stable beams. In some cases where delayed proton emitters are present in the same isobaric chain, the use of the cold reactions with radioactive beams can provide purer samples of the isotope of interest, with a reduction in background from the delayed proton emitters in the same mass chain.

  13. Nonlocality effect in the tunneling of one-proton radioactivity

    NASA Astrophysics Data System (ADS)

    Teruya, N.; Duarte, S. B.; Rodrigues, M. M. N.

    2016-02-01

    A coordinate-dependent effective mass for the proton is considered to calculate half-lives of spontaneous one-proton emission from exotic nuclei. This dynamical change to treat proton-nucleus interaction using this type of effective mass was recently employed successfully for description of proton-nucleus quantum scattering, by Jaghoub et al. [Phys. Rev. C 84, 034618 (2011), 10.1103/PhysRevC.84.034618] and Zureikat and Jaghoub [Nucl. Phys. A 916, 183 (2013), 10.1016/j.nuclphysa.2013.08.007]. The introduced coordinate dependency of the effective mass incorporates nonlocality features of the proton-nucleus interaction for the scattering problem. In the present work the treatment is extended to the proton emission of neutron deficient nuclei. The WKB barrier penetrability factor is determined for proton decay and the half-life is calculated. It is also shown that the tunneling approach is still applicable when a coordinate-dependent effective mass is considered. The real part of the Becchetti and Greenlees [Phys. Rev. 182, 1190 (1969), 10.1103/PhysRev.182.1190] nuclear shell model parametrization is taken to generate the barrier tunneled by the proton. This procedure leads practically to only one free parameter in the effective mass for the entire calculation of the half-lives of the whole set of existing almost spherical proton emitters. In the universe of 32 proton emitters studied we have obtained an excellent agreement for 25 of them, while for the remaining seven emitters it was necessary to add an additional fine tuning, realized by a small change in the nuclear radius parameter definition.

  14. Proton Transport

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  15. Field-emitter arrays for vacuum microelectronics

    NASA Technical Reports Server (NTRS)

    Spindt, C. A.; Holland, C. E.; Rosengreen, A.; Brodie, Ivor

    1991-01-01

    An ongoing program on microfabricated field-emitter arrays has produced a gated field-emitter tip structure with submicrometer dimensions and techniques for fabricating emitter arrays with tip packaging densities of up to 1.5 x 10 exp 7 tips/sq cm. Arrays have been fabricated over areas varying from a few micrometers up to 13 cm in diameter. Very small overall emitter size, materials selection, and rigorous emitter-tip processing procedures have contributed to reducing the potential required for field emission to tens of volts. Emission current densities of up to 100 A/sq cm have been achieved with small arrays of tips, and 100-mA total emission is commonly produced with arrays 1 mm in diameter containing 10,000 tips. Transconductances of 5.0 micro-S per tip have been demonstrated, indicating that 50 S/sq cm should be achievable with tip densities of 10 exp 7 tips/sq cm. Details of the cathode arrays and a variety of performance characteristics are discussed.

  16. Variable emittance behavior of smart radiative coating

    NASA Astrophysics Data System (ADS)

    Guo, Li; Fan, Desong; Li, Qiang

    2016-02-01

    Smart radiative coating on yttria stabilized zirconia (YSZ) substrate was prepared by the sol-gel La{}1-xSr x MnO3 (x = 0.125, 0.175 and 0.2) nanoparticles and the binder composed of terpineol and ethyl cellulose. The crystallized structure, grain size, chemical compositions, magnetization and the surface morphology were characterized. The thermal radiative properties of coating in the infrared range was evaluated from infrared reflectance spectra at various temperatures. A single perovskite structure is detected in sol-gel nanoparticles with size 200 nm. Magnetization measurement reveals that room temperature phase transition samples can be obtained by appropriate Sr substitution. The influence of surface conditions and sintering temperature on the emittance of coating was observed. For rough coatings with root-mean-square roughness 640 nm (x = 0.125) and 800 nm (x = 0.175) , its emittance increment is 0.24 and 0.26 in in the temperature range of 173-373 K. Increasing sintering temperature to 1673 K, coating emittance variation improves to 0.3 and 0.302 respectively. After mechanical polishing treatment, the emittance increment of coatings are enhanced to 0.31 and 0.3, respectively. The results suggested that the emittance variation can be enhanced by reducing surface roughness and increasing sintering temperature of coating.

  17. Emittance control in Laser Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Cheshkov, S.; Tajima, T.; Chiu, C.; Breitling, F.

    2001-05-01

    In this paper we summarize our recent effort and results in theoretical study of the emittance issues of multistaged Laser Wakefield Accelerator (LWFA) in TeV energy range. In such an energy regime the luminosity and therefore the emittance requirements become very stringent and tantamount to the success or failure of such an accelerator. The system of such a machine is very sensitive to jitters due to misalignment between the beam and the wakefield. In particular, the effect of jitters in the presence of a strong focusing wakefield and initial longitudinal phase space spread of the beam leads to severe transverse emittance degradation of the beam. To improve the emittance we introduce several methods: a mitigated wakefield focusing by working with a plasma channel, an approximately synchronous acceleration in a superunit setup, the "horn" model based on exactly synchronous acceleration achieved through plasma density variation and lastly an algorithm based on minimization of the final beam emittance to actively control the stage displacement of such an accelerator.

  18. Integrated photonic crystal selective emitter for thermophotovoltaics

    NASA Astrophysics Data System (ADS)

    Zhou, Zhiguang; Yehia, Omar; Bermel, Peter

    2016-01-01

    Converting blackbody thermal radiation to electricity via thermophotovoltaics (TPV) is inherently inefficient. Photon recycling using cold-side filters offers potentially improved performance but requires extremely close spacing between the thermal emitter and the receiver, namely a high view factor. Here, we propose an alternative approach for thermal energy conversion, the use of an integrated photonic crystal selective emitter (IPSE), which combines two-dimensional photonic crystal selective emitters and filters into a single device. Finite difference time domain and current transport simulations show that IPSEs can significantly suppress sub-bandgap photons. This increases heat-to-electricity conversion for photonic crystal based emitters from 35.2 up to 41.8% at 1573 K for a GaSb photovoltaic (PV) diode with matched bandgaps of 0.7 eV. The physical basis of this enhancement is a shift from a perturbative to a nonperturbative regime, which maximized photon recycling. Furthermore, combining IPSEs with nonconductive optical waveguides eliminates a key difficulty associated with TPV: the need for precise alignment between the hot selective emitter and cool PV diode. The physical effects of both the IPSE and waveguide can be quantified in terms of an extension of the concept of an effective view factor.

  19. Fine-tuning to minimize emittances of J-PARC RF-driven H{sup −} ion source

    SciTech Connect

    Ueno, A. Ohkoshi, K.; Ikegami, K.; Takagi, A.; Asano, H.; Oguri, H.

    2016-02-15

    The Japan Proton Accelerator Research Complex (J-PARC) cesiated RF-driven H{sup −} ion source has been successfully operated for about one year. By the world’s brightest level beam, the J-PARC design beam power of 1 MW was successfully demonstrated. In order to minimize the transverse emittances, the rod-filter-field (RFF) was optimized by changing the triple-gap-lengths of each of pairing five piece rod-filter-magnets. The larger emittance degradation seems to be caused by impurity-gases than the RFF. The smaller beam-hole-diameter of the extraction electrode caused the more than expected improvements on not only the emittances but also the peak beam intensity.

  20. Head erosion with emittance growth in PWFA

    SciTech Connect

    Li, S. Z.; Adli, E.; England, R. J.; Frederico, J.; Gessner, S. J.; Hogan, M. J.; Litos, M. D.; Walz, D. R.; Muggli, P.; An, W.; Clayton, C. E.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W.; Vafaei, N.

    2012-12-21

    Head erosion is one of the limiting factors in plasma wakefield acceleration (PWFA). We present a study of head erosion with emittance growth in field-ionized plasma from the PWFA experiments performed at the FACET user facility at SLAC. At FACET, a 20.3 GeV bunch with 1.8 Multiplication-Sign 10{sup 10} electrons is optimized in beam transverse size and combined with a high density lithium plasma for beam-driven plasma wakefield acceleration experiments. A target foil is inserted upstream of the plasma source to increase the bunch emittance through multiple scattering. Its effect on beamplasma interaction is observed with an energy spectrometer after a vertical bend magnet. Results from the first experiments show that increasing the emittance has suppressed vapor field-ionization and plasma wakefields excitation. Plans for the future are presented.

  1. Solid-state single-photon emitters

    NASA Astrophysics Data System (ADS)

    Aharonovich, Igor; Englund, Dirk; Toth, Milos

    2016-10-01

    Single-photon emitters play an important role in many leading quantum technologies. There is still no 'ideal' on-demand single-photon emitter, but a plethora of promising material systems have been developed, and several have transitioned from proof-of-concept to engineering efforts with steadily improving performance. Here, we review recent progress in the race towards true single-photon emitters required for a range of quantum information processing applications. We focus on solid-state systems including quantum dots, defects in solids, two-dimensional hosts and carbon nanotubes, as these are well positioned to benefit from recent breakthroughs in nanofabrication and materials growth techniques. We consider the main challenges and key advantages of each platform, with a focus on scalable on-chip integration and fabrication of identical sources on photonic circuits.

  2. Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

    NASA Astrophysics Data System (ADS)

    Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R. J. Dwayne

    2016-12-01

    Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence.

  3. Measurement of transverse emittance and coherence of double-gate field emitter array cathodes

    PubMed Central

    Tsujino, Soichiro; Das Kanungo, Prat; Monshipouri, Mahta; Lee, Chiwon; Miller, R.J. Dwayne

    2016-01-01

    Achieving small transverse beam emittance is important for high brightness cathodes for free electron lasers and electron diffraction and imaging experiments. Double-gate field emitter arrays with on-chip focussing electrode, operating with electrical switching or near infrared laser excitation, have been studied as cathodes that are competitive with photocathodes excited by ultraviolet lasers, but the experimental demonstration of the low emittance has been elusive. Here we demonstrate this for a field emitter array with an optimized double-gate structure by directly measuring the beam characteristics. Further we show the successful application of the double-gate field emitter array to observe the low-energy electron beam diffraction from suspended graphene in minimal setup. The observed low emittance and long coherence length are in good agreement with theory. These results demonstrate that our all-metal double-gate field emitters are highly promising for applications that demand extremely low-electron bunch-phase space volume and large transverse coherence. PMID:28008918

  4. Noninterceptive transverse emittance measurements using BPM for Chinese ADS R&D project

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Jun; Feng, Chi; He, Yuan; Dou, Weiping; Tao, Yue; Chen, Wei-long; Jia, Huan; Liu, Shu-hui; Wang, Wang-sheng; Zhang, Yong; Wu, Jian-qiang; Zhang, Sheng-hu; Zhang, X. L.

    2016-04-01

    The noninterceptive four-dimensional transverse emittance measurements are essential for commissioning the high power continue-wave (CW) proton linacs as well as their operations. The conventional emittance measuring devices such as slits and wire scanners are not well suited under these conditions due to sure beam damages. Therefore, the method of using noninterceptive Beam Position Monitor (BPM) is developed and demonstrated on Injector Scheme II at the Chinese Accelerator Driven Sub-critical System (China-ADS) proofing facility inside Institute of Modern Physics (IMP) [1]. The results of measurements are in good agreements with wire scanners and slits at low duty-factor pulsed (LDFP) beam. In this paper, the detailed experiment designs, data analysis and result benchmarking are presented.

  5. SNS Emittance Scanner, Increasing Sensitivity and Performance through Noise Mitigation ,Design, Implementation and Results

    SciTech Connect

    Pogge, J.

    2006-11-20

    The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The SNS MEBT Emittance Harp consists of 16 X and 16 Y wires, located in close proximity to the RFQ, Source, and MEBT Choppers. Beam Studies for source and LINAC commissioning required an overall increase in sensitivity for halo monitoring and measurement, and at the same time several severe noise sources had to be effectively removed from the harp signals. This paper is an overview of the design approach and techniques used in increasing gain and sensitivity while maintaining a large signal to noise ratio for the emittance scanner device. A brief discussion of the identification of the noise sources, the mechanism for transmission and pick up, how the signals were improved and a summary of results.

  6. Proton Therapy

    MedlinePlus

    ... effects of the treatment. top of page What equipment is used? Proton beam therapy uses special machines, ... tumor cells. top of page Who operates the equipment? With backgrounds in mechanical, electrical, software, hardware and ...

  7. Current Injection Pumping of Organic Light Emitters

    DTIC Science & Technology

    1989-09-28

    MOT-OOO1AF I Current Injection Pumping of Organic Light Emitters Prepared by DI Jeffrey C. Buchholz E L ri: 8 James P. Stec OCT C "t989 Mary C...Schutte Micro -Optics Technologies, Inc. 8608 University Green #5 Middleton, WI 53562 28 September 1989 D,:?UqflON SA2". N’.’ _ Disuibunon Uanu-ted Contract...Title Report Date Current Injection Pumping of Organic Light Emitters 28 September 1989 Authors Jeffrey C. Buchholz, James P. Stec, Mary C. Schutte

  8. Field emitter technologies for nanovision science

    NASA Astrophysics Data System (ADS)

    Mimura, H.; Neo, Y.; Aoki, T.; Nagao, M.; Yoshida, T.; Kanemaru, S.

    2009-10-01

    We have been investigating an ultra fine field emission display (FED) and an ultra fine CdTe X-ray image sensor for creating nanovision science. For an ultra fine FED with a sub-micron pixel, we have developed a volcano-structured double-gated field emitter arrays with a capability of focusing electron beam without serous reduction in emission current. For an ultra fine X-ray image sensor, we have proposed and demonstrated a novel CdTe X-ray sensor consisting of a CdTe diode and field emitter array.

  9. Coupling single emitters to quantum plasmonic circuits

    NASA Astrophysics Data System (ADS)

    Huck, Alexander; Andersen, Ulrik L.

    2016-09-01

    In recent years, the controlled coupling of single-photon emitters to propagating surface plasmons has been intensely studied, which is fueled by the prospect of a giant photonic nonlinearity on a nanoscaled platform. In this article, we will review the recent progress on coupling single emitters to nanowires towards the construction of a new platform for strong light-matter interaction. The control over such a platform might open new doors for quantum information processing and quantum sensing at the nanoscale and for the study of fundamental physics in the ultrastrong coupling regime.

  10. Heterojunction solar cell with passivated emitter surface

    DOEpatents

    Olson, J.M.; Kurtz, S.R.

    1994-05-31

    A high-efficiency heterojunction solar cell is described wherein a thin emitter layer (preferably Ga[sub 0.52]In[sub 0.48]P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer. 1 fig.

  11. Heterojunction solar cell with passivated emitter surface

    DOEpatents

    Olson, Jerry M.; Kurtz, Sarah R.

    1994-01-01

    A high-efficiency heterojunction solar cell wherein a thin emitter layer (preferably Ga.sub.0.52 In.sub.0.48 P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer.

  12. Determination and error analysis of emittance and spectral emittance measurements by remote sensing

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N. (Principal Investigator); Kumar, R.

    1977-01-01

    The author has identified the following significant results. From the theory of remote sensing of surface temperatures, an equation of the upper bound of absolute error of emittance was determined. It showed that the absolute error decreased with an increase in contact temperature, whereas, it increased with an increase in environmental integrated radiant flux density. Change in emittance had little effect on the absolute error. A plot of the difference between temperature and band radiance temperature vs. emittance was provided for the wavelength intervals: 4.5 to 5.5 microns, 8 to 13.5 microns, and 10.2 to 12.5 microns.

  13. Theoretical investigation on the effect of protonation on the absorption and emission spectra of two amine-group-bearing, red "push-pull" emitters, 4-dimethylamino-4'-nitrostilbene and 4-(dicyanomethylene)-2-methyl-6-p-(dimethylamino) styryl-4H-pyran, by DFT and TDDFT calculations.

    PubMed

    Petsalakis, I D; Georgiadou, D G; Vasilopoulou, M; Pistolis, G; Dimotikali, D; Argitis, P; Theodorakopoulos, G

    2010-05-06

    A theoretical investigation on the electronic structure of 4-dimethylamino-4'-nitrostilbene (DANS), 4-(dicyanomethylene)-2-methyl-6-p-(dimethylamino) styryl-4H-pyran (DCM), and their protonated forms is presented in an effort to rationalize recent experimental results on the tuning of the emitted color of organic light-emitting diodes through photochemically induced protonation. Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been carried out on the neutral and protonated forms of DANS and DCM, employing both the B3LYP and the CAM-B3LYP functionals. It was found that the CAM-B3LYP functional leads to better agreement than the B3LYP of the calculated with the experimental absorption lambda(max) for DANS, whereas B3LYP is more appropriate than CAM-B3LYP for DCM. The results of the calculations aid in a rationalization of the observed differences of the spectra of DANS and DCM upon protonation, and in particular those differences that make DANS a more attractive system for absorbance and emission tuning.

  14. A study of emittance growth in the recycler ring

    SciTech Connect

    Krishnaswamy Gounder et al.

    2001-07-20

    We investigate processes contributing to emittance growth in the Fermilab Recycler Ring. In addition to beam-gas multiple scattering, we also examine other external factors such as Main Injector ramping affecting the emittance growth.

  15. Emittance Characteristics of High-Brightness H- Ion Sources

    NASA Astrophysics Data System (ADS)

    Welton, R. F.; Stockli, M. P.; Keller, R.; Thomae, R. W.; Thomason, J.; Sherman, J.; Alessi, J.

    2002-11-01

    A survey of emittance characteristics from high-brightness, H- ion sources has been undertaken. Representative examples of each important type of H- source for accelerator application are investigated: A magnetron surface plasma source (BNL) a multi-cusp-surface-conversion source (LANL) a Penning source (RAL-ISIS) and a multi-cusp-volume source (LBNL). Presently, comparisons between published emittance values from different ion sources are difficult largely because of different definitions used in reported emittances and the use of different data reduction techniques in analyzing data. Although seldom discussed in the literature, rms-emittance values often depend strongly on the method employed to separate real beam from background. In this work, the problem of data reduction along with software developed for emittance analysis is discussed. Raw emittance data, obtained from the above laboratories, is analyzed using a single technique and normalized rms and 90% area-emittance values are determined along with characteristic emittance versus beam fraction curves.

  16. Emittance growth rates for displaced beams

    SciTech Connect

    Anderson, O.A. |

    1993-05-01

    Emittance growth rates have been previously analyzed for nonuniform beams in linear channels and for initially uniform mismatched beams in nonlinear channels. These studies were for centered beams. Additional emittance growth can arise in cases where the beam is initially displaced. The purpose of this study is to obtain growth rates for displaced beams. This work differs from studies involving random displacement of electrodes. Our analysis assumes instead that the focusing system is perfectly aligned but that the beam is initially displaced with respect to the equilibrium axis. If the focusing force is slightly nonlinear, we find a gradual transfer of the potential energy of beam displacement into kinetic energy associated with emittance growth. We present explicit results for the emittance growth distance as a function of the nonlinearity of the channel. These results will have practical importance for designers of accelerators and transport systems when setting realistic tolerances for initial beam alignment. These tolerances will depend on the nonlinearity and the length of the system.

  17. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  18. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus_minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus_minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  19. Light modulated electron beam driven radiofrequency emitter

    DOEpatents

    Wilson, M.T.; Tallerico, P.J.

    1979-10-10

    The disclosure relates to a light modulated electron beam-driven radiofrequency emitter. Pulses of light impinge on a photoemissive device which generates an electron beam having the pulse characteristics of the light. The electron beam is accelerated through a radiofrequency resonator which produces radiofrequency emission in accordance with the electron, hence, the light pulses.

  20. Light modulated switches and radio frequency emitters

    DOEpatents

    Wilson, Mahlon T.; Tallerico, Paul J.

    1982-01-01

    The disclosure relates to a light modulated electron beam driven radiofrequency emitter. Pulses of light impinge on a photoemissive device which generates an electron beam having the pulse characteristics of the light. The electron beam is accelerated through a radiofrequency resonator which produces radiofrequency emission in accordance with the electron, hence, the light pulses.

  1. Simple-to-prepare multipoint field emitter

    NASA Astrophysics Data System (ADS)

    Sominskii, G. G.; Taradaev, E. P.; Tumareva, T. A.; Mishin, M. V.; Kornishin, S. Yu.

    2015-07-01

    We investigate multitip field emitters prepared by electroerosion treatment of the surface of molybdenum samples. Their characteristics are determined for operation with a protecting activated fullerene coating. Our experiments indicate that such cathodes are promising for high-voltage electron devices operating in technical vacuum.

  2. Emittance growth from electron beam modulation

    SciTech Connect

    Blaskiewicz, M.

    2009-12-01

    In linac ring colliders like MeRHIC and eRHIC a modulation of the electron bunch can lead to a modulation of the beam beam tune shift and steering errors. These modulations can lead to emittance growth. This note presents simple formulas to estimate these effects which generalize some previous results.

  3. Optical transition radiation beam emittance diagnostics

    SciTech Connect

    Fiorito, R.B.; Rule, D.W.

    1994-10-10

    We have developed several analytic and experimental techniques to measure the divergence and emittance of charged particle beams, which employ optical transition radiation (OTR) produced from thin intercepting foils. OTR`s directionality, promptness, linearity, polarization, and the sensitivity of its angular distribution to energy and divergence, can be all exploited to diagnose the spatial distribution, energy, and emittance of a charged particle beam. We describe the techniques we have developed to separately determine the {ital x} and {ital y} emittances of a beam at an {ital x} or {ital y} waist using OTR from a single foil or a two foil OTR interferometer. These methods have proven to be especially valuable for diagnosing low emittance electron beams produced by FEL accelerators, which range in energy from 17 to 110 Mev. However, we have shown that there is no inherent theoretical limit to the utility of these methods for much higher energy lepton or hadron beams. The advantages of OTR methods over those commonly used to diagnose beam properties are described.

  4. Emittance growth from space-charge forces

    SciTech Connect

    Wangler, T.P.

    1991-01-01

    Space-charge-induced emittance growth has become a topic of much recent interest for designing the low-velocity sections of high- intensity, high-brightness accelerators and beam-transport channels. In this paper we review the properties of the space-charge force, and discuss the concepts of matching, space-charge and emittance-dominated beams, and equilibrium beams and their characteristics. This is followed by a survey of some of the work over the past 25 years to identify the mechanisms of this emittance growth in both ion and electron accelerators. We summarize the overall results in terms of four distinct mechanisms whose characteristics we describe. Finally, we show numerical simulation results for the evolution of initial rms-mismatched laminar beams. The examples show that for space-charge dominated beams, the nonlinear space-charge forces produce a highly choatic filamentation pattern, which in projection to the 2-D phase spaces results in a 2-component beam consisting of an inner core and a diffuse outer halo. In the examples we have studied the halo contains only a few percent of the particles, but contributes about half of the emittance growth. 39 refs., 2 figs., 1 tab.

  5. Self-powered radiation detector with conductive emitter support

    SciTech Connect

    Bauer, R.F.; Goldstein, N.P.; Playfoot, K.C.

    1981-05-12

    A more reliable self-powered radiation detector structure and method of manufacture is provided by a detector structure in which a relatively ductile centrally disposed conductive emitter wire supports and is in electrical contact with a generally tubular emitter electrode. The detector is fabricated by swaging and the ductile center wire insures that electrical discontinuities of the emitter are minimized.

  6. What is so super about super-emitters? Characterizing methane high emitters from natural gas infrastructure

    NASA Astrophysics Data System (ADS)

    Zavala Araiza, D.; Lyon, D. R.; Alvarez, R.; Harriss, R. C.; Palacios, V.; Hamburg, S.

    2015-12-01

    Methane emissions across the natural gas supply chain are dominated at any one time by a few high-emitters (super-emitters or fat-tail of the distribution), often underrepresented in published datasets used to construct emission inventories. Characterization of high-emitters is essential for improving emission estimates based on atmospheric data (top-down) and emission inventories (bottom-up). The population of high-emitters (e.g. 10-20% of sites that account for 80-90% of the emissions) is temporally and spatially dynamic. As a consequence, it is challenging to design sampling methods and construct estimates that accurately represent their frequency and magnitude of emissions. We present new methods to derive facility-specific emission distribution functions that explicitly integrate the influence of the relatively rare super-emitters. These methods were applied in the Barnett Shale region to construct a custom emission inventory that is then compared to top-down emission estimates for the region. We offer a methodological framework relevant to the design of future sampling campaigns, in which these high-emitters are seamlessly incorporated to representative emissions distributions. This framework can be applied to heterogeneous oil and gas production regions across geographies to obtain accurate regional emission estimates. Additionally, we characterize emissions relative to the fraction of a facility's total methane throughput; an effective metric to identify sites with excess emissions resulting from avoidable operating conditions, such as malfunctioning equipment (defined here as functional super-emitters). This work suggests that identifying functional super-emitters and correcting their avoidable operating conditions would result in significant emission reductions. However, due to their spatiotemporal dynamic behavior, achieving and maintaining uniformly low emissions across the entire population of sites will require mitigation steps (e.g. leak detection

  7. Calculations on decay rates of various proton emissions

    NASA Astrophysics Data System (ADS)

    Qian, Yibin; Ren, Zhongzhou

    2016-03-01

    Proton radioactivity of neutron-deficient nuclei around the dripline has been systematically studied within the deformed density-dependent model. The crucial proton-nucleus potential is constructed via the single-folding integral of the density distribution of daughter nuclei and the effective M3Y nucleon-nucleon interaction or the proton-proton Coulomb interaction. After the decay width is obtained by the modified two-potential approach, the final decay half-lives can be achieved by involving the spectroscopic factors from the relativistic mean-field (RMF) theory combined with the BCS method. Moreover, a simple formula along with only one adjusted parameter is tentatively proposed to evaluate the half-lives of proton emitters, where the introduction of nuclear deformation is somewhat discussed as well. It is found that the calculated results are in satisfactory agreement with the experimental values and consistent with other theoretical studies, indicating that the present approach can be applied to the case of proton emission. Predictions on half-lives are made for possible proton emitters, which may be useful for future experiments.

  8. Facet engineering of high power single emitters

    NASA Astrophysics Data System (ADS)

    Yanson, Dan; Levi, Moshe; Shamay, Moshe; Tesler, Renana; Rappaport, Noam; Don, Yaroslav; Karni, Yoram; Schnitzer, Itzhak; Sicron, Noam; Shusterman, Sergey

    2011-03-01

    The ever increasing demand for high-power, high-reliability operation of single emitters at 9xx nm wavelengths requires the development of laser diodes with improved facet regions immune to both catastrophic and wear-out failure modes. In our study, we have evaluated several laser facet definition technologies in application to 90 micron aperture single emitters in asymmetric design (In)GaAs/AlGaAs based material emitting at 915, 925 and 980nm. A common epitaxy and emitter design makes for a straightforward comparison of the facet technologies investigated. Our study corroborates a clear trend of increasing difficulty in obtaining reliable laser operation from 980nm down to 915nm. At 980nm, one can employ dielectric facet passivation with a pre-clean cycle delivering a device lifetime in excess of 3,000 hours at increasing current steps. At 925nm, quantum-well intermixing can be used to define non-absorbing mirrors giving good device reliability, albeit with a large efficiency penalty. Vacuum cleaved emitters have delivered excellent reliability at 915nm, and can be expected to perform just as well at 925 and 980nm. Epitaxial regrowth of laser facets is under development and has yet to demonstrate an appreciable reliability improvement. Only a weak correlation between start-of-life catastrophic optical mirror damage (COMD) levels and reliability was established. The optimized facet design has delivered maximum powers in excess of 19 MW/sq.cm (rollover limited) and product-grade 980nm single emitters with a slope efficiency of >1 W/A and a peak efficiency of >60%. The devices have accumulated over 1,500 hours of CW operation at 11W. A fiber-coupled device emits 10W ex-fiber with 47% efficiency.

  9. High-Intensity Proton Accelerator

    SciTech Connect

    Jay L. Hirshfield

    2011-12-27

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

  10. Description of proton radioactivity using the Coulomb and proximity potential model for deformed nuclei

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Sukumaran, Indu

    2017-09-01

    Half-life predictions have been performed for the proton emitters with Z >50 in the ground state and isomeric state using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The agreement of the calculated values with the experimental data made it possible to predict some proton emissions that are not verified experimentally yet. For a comparison, the calculations also are performed using other theoretical models, such as the Gamow-like model of Zdeb et al. [Eur. Phys. J. A 52, 323 (2016), 10.1140/epja/i2016-16323-7], the semiempirical relation of Hatsukawa et al. [Phys. Rev. C 42, 674 (1990), 10.1103/PhysRevC.42.674], and the CPPM of Santhosh et al. [Pramana 58, 611 (2002)], 10.1007/s12043-002-0019-2. The Geiger-Nuttall law, originally observed for α decay, studied for proton radioactivity is found to work well provided it is plotted for the isotopes of a given proton emitter nuclide with the same ℓ value. The universal curve is found to be valid for proton radioactivity also as we obtained a single straight line for all proton emissions irrespective of the parents. Through the analysis of the experimentally measured half-lives of 44 proton emitters, the study revealed that the present systematic study lends support to a unified description for studying α decay, cluster radioactivity, and proton radioactivity.

  11. Spectral and Total Normal Emittance of Reusable Surface Insulation Materials

    NASA Technical Reports Server (NTRS)

    Kantsios, A. G.; Edwards, S. F.; Dicus, D. L.

    1973-01-01

    Measurements of spectral and total normal emittance have been made on three types of reusable external insulation materials proposed for space shuttles. Emittances were measured in the spectral range 1 to 15 micrometer at temperatures of 800 K and 1100 K using a radiometric measurement technique. Results indicated that the total normal emittance of these materials was less than 0.8 between 800 K and 1300 K. The total normal emittance decreased with increasing temperature. The three ceramic coating candidate materials exhibited a similar spectral emittance distribution.

  12. DEVELOPMENT OF EMITTANCE ANALYSIS SOFTWARE FOR ION BEAM CHARACTERIZATION

    SciTech Connect

    Padilla, M. J.; Liu, Y.

    2007-01-01

    Transverse beam emittance is a crucial property of charged particle beams that describes their angular and spatial spread. It is a fi gure of merit frequently used to determine the quality of ion beams, the compatibility of an ion beam with a given beam transport system, and the ability to suppress neighboring isotopes at on-line mass separator facilities. Generally a high quality beam is characterized by a small emittance. In order to determine and improve the quality of ion beams used at the Holifi eld Radioactive Ion beam Facility (HRIBF) for nuclear physics and nuclear astrophysics research, the emittances of the ion beams are measured at the off-line Ion Source Test Facilities. In this project, emittance analysis software was developed to perform various data processing tasks for noise reduction, to evaluate root-mean-square emittance, Twiss parameters, and area emittance of different beam fractions. The software also provides 2D and 3D graphical views of the emittance data, beam profi les, emittance contours, and RMS. Noise exclusion is essential for accurate determination of beam emittance values. A Self-Consistent, Unbiased Elliptical Exclusion (SCUBEEx) method is employed. Numerical data analysis techniques such as interpolation and nonlinear fi tting are also incorporated into the software. The software will provide a simplifi ed, fast tool for comprehensive emittance analysis. The main functions of the software package have been completed. In preliminary tests with experimental emittance data, the analysis results using the software were shown to be accurate.

  13. EMITTANCE GROWTH IN THE FEL RF-GUN

    SciTech Connect

    Novokhatski, Alexander

    2002-08-20

    A high brightness and low emittance is of crucial importance for the SASE-FEL at the TESLA Test Facility. Therefore a Photo-RF-Gun has been installed as particle source. Numerical simulations with codes like ASTRA [1] and MAFIA [2] show that the space charge dominated processes inside the RF-Gun contribute significantly to the emittance. In this paper we present the results of detailed studies with MAFIA TS2 which clarify the effects resulting in emittance growth for space charge dominated beams. It is shown that the resulting emittance can be minimized by changing the laser parameters like pulse length and spot size on the cathode. Additionally we present the concept of slice emittances which allows a more precise prediction of the real transverse emittance achievable with an emittance compensation scheme.

  14. Edge enhancement control in linear arrays of ungated field emitters

    NASA Astrophysics Data System (ADS)

    Harris, J. R.; Jensen, K. L.; Shiffler, D. A.

    2016-01-01

    In arrays of ungated field emitters, the field enhancement factor of each emitter decreases as the distance between the emitters decreases, an effect known as screening. At the edge of these arrays, emitters experience reduced screening, leading to higher field enhancement factors than emitters at the array center, causing nonuniform emission across the array. Here, we consider this effect in linear arrays of ungated field emitters spaced at distances comparable to their heights, which is the regime that generally maximizes their average current density. A Line Charge Model is used to assess the degree to which these edge effects propagate into the array interior, and to study the impact of varying the height, location, and tip radius of emitters at the ends of an array on the edge enhancement. It is shown that each of these techniques can accomplish this edge enhancement control, but each has advantages and disadvantages that will be discussed.

  15. Proton Therapy

    MedlinePlus

    ... Liver Breast Esophagus Rectum Skull base sarcomas Pediatric brain tumors Head and neck - see the Head and Neck Cancer page Eye ... Intensity-Modulated Radiation Therapy (IMRT) Brain Tumor Treatment Brain Tumors Prostate Cancer Lung Cancer ... related to Proton Therapy Videos related ...

  16. Proton geriatrics

    NASA Astrophysics Data System (ADS)

    Kephart, Thomas W.; Nakagawa, Norio

    1984-07-01

    An SO(10) model with particle spectrum and low energy gauge group identical to that of minimal SU (5) below MX but with a nonstandard charge assignment is shown to agree with the experimental best value of sin2θw(Mw) and the lower bound on the proton lifetime.

  17. Proton Radiobiology

    PubMed Central

    Tommasino, Francesco; Durante, Marco

    2015-01-01

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

  18. Dynamics of proton diffusion within the hydration layer of phospholipid membrane

    SciTech Connect

    Gutman, M.; Nachliel, E.; Moshiach, S.

    1989-04-04

    The diffusion of protons at the immediate vicinity of (less than 10 A from) a phospholipid membrane is studied by the application of the laser-induced proton pulse. A light-sensitive proton emitter (8-hydroxypyrene-1,3,6-trisulfonate) was trapped exclusively in the hydration layers of multilamellar vesicles made of egg phosphatidylcholine, and the protons were dissociated by a synchronizing laser pulse. The recombination of the proton with pyranin anion was monitored by time-resolved spectroscopy and analyzed by a diffusion-controlled formalism. The measured diffusion coefficient is only slightly smaller than the diffusion coefficient of proton in bulk water. Modulating the width of the hydration layer by external pressure had a direct effect on the diffusibility of the proton: the narrower the hydration layer, the slower is the diffusion of protons.

  19. Integrated compact optical vortex beam emitters.

    PubMed

    Cai, Xinlun; Wang, Jianwei; Strain, Michael J; Johnson-Morris, Benjamin; Zhu, Jiangbo; Sorel, Marc; O'Brien, Jeremy L; Thompson, Mark G; Yu, Siyuan

    2012-10-19

    Emerging applications based on optical beams carrying orbital angular momentum (OAM) will probably require photonic integrated devices and circuits for miniaturization, improved performance, and enhanced functionality. We demonstrate silicon-integrated optical vortex emitters, using angular gratings to extract light confined in whispering gallery modes with high OAM into free-space beams with well-controlled amounts of OAM. The smallest device has a radius of 3.9 micrometers. Experimental characterization confirms the theoretical prediction that the emitted beams carry exactly defined and adjustable OAM. Fabrication of integrated arrays and demonstration of simultaneous emission of multiple identical optical vortices provide the potential for large-scale integration of optical vortex emitters on complementary metal-oxide-semiconductor compatible silicon chips for wide-ranging applications.

  20. Ghost signals in Allison emittance scanners

    SciTech Connect

    Stockli, Martin P.; Leitner, M.; Moehs, D.P.; Keller, R.; Welton, R.F.; /SNS Project, Oak Ridge /Tennessee U.

    2004-12-01

    For over 20 years, Allison scanners have been used to measure emittances of low-energy ion beams. We show that scanning large trajectory angles produces ghost signals caused by the sampled beamlet impacting on an electric deflection plate. The ghost signal strength is proportional to the amount of beam entering the scanner. Depending on the ions, and their velocity, the ghost signals can have the opposite or the same polarity as the main beam signals. The ghost signals cause significant errors in the emittance estimates because they appear at large trajectory angles. These ghost signals often go undetected because they partly overlap with the real signals, are mostly below the 1% level, and often hide in the noise. A simple deflection plate modification is shown to reduce the ghost signal strength by over 99%.

  1. Photonic Crystal Emitters for Thermophotovoltaic Energy Conversion

    NASA Astrophysics Data System (ADS)

    Stelmakh, Veronika; Chan, Walker R.; Ghebrebrhan, Michael; Soljacic, Marin; Joannopoulos, John D.; Celanovic, Ivan

    2015-12-01

    This paper reports the design, fabrication, and characterization of 2D photonic crystal (PhC) thermal emitters for a millimeter-scale hydrocarbon TPV microgenerator as a possible replacement for batteries in portable microelectronics, robotics, etc. In our TPV system, combustion heats a PhC emitter to incandescence and the resulting radiation is converted by a low-bandgap TPV cell. The PhC tailors the photonic density of states to produce spectrally confined thermal emission that matches the bandgap of the TPV cell, enabling high heat-to-electricity conversion efficiency. The work builds on a previously developed fabrication process to produce a square array of cylindrical cavities in a metal substrate. We will present ongoing incremental improvements in the optical and thermo-mechanical properties, the fabrication process, and the system integration, as recently combined with fabrication using novel materials, such as sputtered coatings, to enable a monolithic system.

  2. Computing Eigen-Emittances from Tracking Data

    SciTech Connect

    Alexahin, Y.

    2014-09-18

    In a strongly nonlinear system the particle distribution in the phase space may develop long tails which contribution to the covariance (sigma) matrix should be suppressed for a correct estimate of the beam emittance. A method is offered based on Gaussian approximation of the original particle distribution in the phase space (Klimontovich distribution) which leads to an equation for the sigma matrix which provides efficient suppression of the tails and cannot be obtained by introducing weights. This equation is easily solved by iterations in the multi-dimensional case. It is also shown how the eigen-emittances and coupled optics functions can be retrieved from the sigma matrix in a strongly coupled system. Finally, the developed algorithm is applied to 6D ionization cooling of muons in HFOFO channel.

  3. FIrpic: archetypal blue phosphorescent emitter for electroluminescence.

    PubMed

    Baranoff, Etienne; Curchod, Basile F E

    2015-05-14

    FIrpic is the most investigated bis-cyclometallated iridium complex in particular in the context of organic light emitting diodes (OLEDs) because of its attractive sky-blue emission, high emission efficiency, and suitable energy levels. In this Perspective we review the synthesis, structural characterisations, and key properties of this emitter. We also survey the theoretical studies and summarise a series of selected monochromatic electroluminescent devices using FIrpic as the emitting dopant. Finally we highlight important shortcomings of FIrpic as an emitter for OLEDs. Despite the large body of work dedicated to this material, it is manifest that the understanding of photophysical and electrochemical processes are only broadly understood mainly because of the different environment in which these properties are measured, i.e., isolated molecules in solvent vs. device.

  4. Development of arrayed microcolumns and field emitters

    NASA Astrophysics Data System (ADS)

    Kim, Ho Seob; Bok Lee, Young; Choi, Sung Woong; Kim, Hyung Woo; Kim, Dae-Wook; Ahn, Seung Joon; Oh, Tae Sik; Song, Yoon-Ho; Chon Park, Byong; Jong Lim, Sun

    2017-06-01

    Electron beam devices have been widely used for inspection or lithography processes. The multibeam technology based on arrayed microcolumns has been developed to overcome the low throughput issue. However, the multicolumn system has some drawbacks such as complexity, electron optics, and electron source. The first drawback is the difficulty in multicolumn assembly. In particular, the alignment process of a source lens and a tip requires sophisticated techniques. The second drawback is that the e-beam characteristics of microcolumns constituting the multicolumn differ from column to column. To solve the first drawback, a sub-5-nm-resolution probe beam optic design with a simple structure and a two-dimensional carbon nanotube (2D-CNT) electron emitter instead of the widely used tungsten field emitter tip have been studied.

  5. Front contact solar cell with formed emitter

    DOEpatents

    Cousins, Peter John

    2014-11-04

    A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

  6. Front contact solar cell with formed emitter

    DOEpatents

    Cousins, Peter John [Menlo Park, CA

    2012-07-17

    A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

  7. Is there life after thermal emitters?

    NASA Astrophysics Data System (ADS)

    Malyutenko, V.

    2007-04-01

    In this report, we examine whether photonic IR emitters are able to compete with advanced thermal microemitter technology in testing and stimulating IR sensors, including forward-looking IR missile warning systems, IR search-and-track devices, and missile seekers. We consider fundamentals, technology, and parameters of photonic devices as well as their pros and cons in respect to thermal emitters. In particular, we show that photonic devices can from platform for next generation of multi-spectral and hyper-spectral dynamic scene simulation devices operating inside MWIR and LWIR bands with high spectral output density and able to simulate dynamically cold scenes (without cryogenic cooling) and low observable with very high frame rate.

  8. Reverse Emittance Exchange for Muon Colliders

    SciTech Connect

    V. Ivanov, A. Afanasev, C.M. Ankenbrandt, R.P. Johnson, G.M. Wang, S.A. Bogacz, Y.S. Derbenev

    2009-05-01

    Muon collider luminosity depends on the number of muons in the storage ring and on the transverse size of the beams in collision. Ionization cooling as it is currently envisioned will not cool the beam sizes sufficiently well to provide adequate luminosity without large muon intensities. Six-dimensional cooling schemes will reduce the longitudinal emittance of a muon beam so that smaller high frequency RF cavities can be used for later stages of cooling and for acceleration. However, the bunch length at collision energy is then shorter than needed to match the interaction region beta function. New ideas to shrink transverse beam dimensions by lengthening each bunch will help achieve high luminosity in muon colliders. Analytic expressions for the reverse emittance exchange mechanism were derived, including a new resonant method of beam focusing.

  9. RF Emitter Tracking and Intent Assessment

    DTIC Science & Technology

    2013-03-21

    the US Navy. The paper communicated that the Navy requires accurate detecting , locating and tracking of mobile RF emitters. The system design used...x3 are voltage readings taken from different locations in the substation . PA and PB represent the probabilities of a real fault and fake fault...Borghetti, “A Review of Anomaly Detection in Automated Surveillance,” IEEE Transactions on Systems , Man, and Cybernetics, Part C: Applications and Reviews

  10. Complementary methods of transverse emittance measurement

    SciTech Connect

    Zagel, James; Hu, Martin; Jansson, Andreas; Thurman-Keup, Randy; Yan, Ming-Jen; /Fermilab

    2008-05-01

    Several complementary transverse emittance monitors have been developed and used at the Fermilab accelerator complex. These include Ionization profile Monitors (IPM), Flying Wires, Schottky detectors and a Synchrotron Light Monitor (Synchlite). Mechanical scrapers have also been used for calibration purposes. This paper describes the various measurement devices by examining their basic features, calibration requirements, systematic uncertainties, and applications to collider operation. A comparison of results from different kinds of measurements is also presented.

  11. Emittance of a Field Emission Electron Source

    DTIC Science & Technology

    2010-01-05

    mode within the wiggler in order for the laser threshold to be reached. The mode is characterized by a waist radius w and a divergence , the product...the field line red or curved compared to a massive particle trajectory blue or straight. The field lines originate on the surface at s ,zs and...emitter surface s ,zs and along the evalu- ation plane h ,zh. The equivalent sphere characterized by a , is also shown. The red curved line

  12. Multiwire secondary-emission monitor and the emittance measurement of the AGS beam

    SciTech Connect

    Weng, W.T.; Chiang, I.H.; Smith, G.A.; Soukas, A.

    1983-01-01

    For CBA injection the transverse emittances and the Twiss parameters of the AGS beam have to be well defined to minimize the phase space dilution in CBA. Althoug there exists a profile monitor device at U165, there are three reasons why construction of multiwire profile monitor system at three locations from U500 to U168 is required: (1) the dispersion function is not zero at U165 which makes it harder to interpret the measurement; (2) the original single wire device takes five minutes to traverse the whole beam; (3) a three station multiwire system can provide the profile information at all locations in one pulse which makes on-line analysis possible. In summary, a set of three stations of Multiwire Secondary Emission Monitor (MSEM) has been built and installed in the fast external beam line for the measurement of beam profiles. Each unit consists of two planes each with 30 nickel wires having a diameter of 5 mils. The signal is linear within the range of 10/sup 10/ to 10/sup 13/ incident protons on the wire and the resolution of the signal is well within a few percent. A least-square fitting routine has been used to extract the emittance and phase space parameters of the beam. The emittances obtained at various intensities will help us to understand the AGS acceleration process and to choose the optimal injection scheme for CBA.

  13. Experimental results of the laserwire emittance scanner for LINAC4 at CERN

    NASA Astrophysics Data System (ADS)

    Hofmann, Thomas; Boorman, Gary E.; Bosco, Alessio; Bravin, Enrico; Gibson, Stephen M.; Kruchinin, Konstantin O.; Raich, Uli; Roncarolo, Federico; Zocca, Francesca

    2016-09-01

    Within the framework of the LHC Injector Upgrade (LIU), the new LINAC4 is currently being commissioned to replace the existing LINAC2 proton source at CERN. After the expected completion at the end of 2016, the LINAC4 will accelerate H- ions to 160 MeV. To measure the transverse emittance of the H- beam, a method based on photo-detachment is proposed. This system will operate using a pulsed laser with light delivered via an optical fibre and subsequently focused onto the H- beam. The laser photons have sufficient energy to detach the outer electron and create H0/e- pairs. In a downstream dipole, the created H0 particles are separated from the unstripped H- ions and their distribution is measured with a dedicated detector. By scanning the focused laser beam across the H- beam, the transverse emittance of the H- beam can be reconstructed. This paper will first discuss the concept, design and simulations of the laser emittance scanner and then present results from a prototype system used during the 12 MeV commissioning of the LINAC4.

  14. ALMA deep field in SSA22: Blindly detected CO emitters and [C II] emitter candidates

    NASA Astrophysics Data System (ADS)

    Hayatsu, Natsuki H.; Matsuda, Yuichi; Umehata, Hideki; Yoshida, Naoki; Smail, Ian; Swinbank, A. Mark; Ivison, Rob; Kohno, Kotaro; Tamura, Yoichi; Kubo, Mariko; Iono, Daisuke; Hatsukade, Bunyo; Nakanishi, Kouichiro; Kawabe, Ryohei; Nagao, Tohru; Inoue, Akio K.; Takeuchi, Tsutomu T.; Lee, Minju; Ao, Yiping; Fujimoto, Seiji; Izumi, Takuma; Yamaguchi, Yuki; Ikarashi, Soh; Yamada, Toru

    2017-06-01

    We report the identification of four millimeter line-emitting galaxies with the Atacama Large Milli/submillimeter Array (ALMA) in SSA22 Field (ADF22). We analyze the ALMA 1.1-mm survey data, with an effective survey area of 5 arcmin2, frequency ranges of 253.1-256.8 and 269.1-272.8 GHz, angular resolution of 0{^''.}7 and rms noise of 0.8 mJy beam-1 at 36 km s-1 velocity resolution. We detect four line-emitter candidates with significance levels above 6σ. We identify one of the four sources as a CO(9-8) emitter at z = 3.1 in a member of the proto-cluster known in this field. Another line emitter with an optical counterpart is likely a CO(4-3) emitter at z = 0.7. The other two sources without any millimeter continuum or optical/near-infrared counterpart are likely to be [C II] emitter candidates at z = 6.0 and 6.5. The equivalent widths of the [C II] candidates are consistent with those of confirmed high-redshift [C II] emitters and candidates, and are a factor of 10 times larger than that of the CO(9-8) emitter detected in this search. The [C II] luminosity of the candidates are 4-7 × 108 L⊙. The star formation rates (SFRs) of these sources are estimated to be 10-20 M⊙ yr-1 if we adopt an empirical [C II] luminosity-SFR relation. One of them has a relatively low S/N ratio, but shows features characteristic of emission lines. Assuming that at least one of the two candidates is a [C II] emitter, we derive a lower limit of [C II]-based star formation rate density (SFRD) at z ∼ 6. The resulting value of >10-2 M⊙ yr-1 Mpc-3 is consistent with the dust-uncorrected UV-based SFRD. Future millimeter/submillimeter surveys can be used to detect a number of high-redshift line emitters, with which to study the star formation history in the early universe.

  15. Proton radioactivity within a generalized liquid drop model

    SciTech Connect

    Dong, J. M.; Zhang, H. F.; Royer, G.

    2009-05-15

    The proton radioactivity half-lives of spherical proton emitters are investigated theoretically. The potential barriers preventing the emission of protons are determined in the quasimolecular shape path within a generalized liquid drop model (GLDM) including the proximity effects between nuclei in a neck and the mass and charge asymmetry. The penetrability is calculated with the WKB approximation. The spectroscopic factor has been taken into account in half-life calculation, which is obtained by employing the relativistic mean field (RMF) theory combined with the BCS method with the force NL3. The half-lives within the GLDM are compared with the experimental data and other theoretical values. The GLDM works quite well for spherical proton emitters when the spectroscopic factors are considered, indicating the necessity of introducing the spectroscopic factor and the success of the GLDM for proton emission. Finally, we present two formulas for proton emission half-life calculation similar to the Viola-Seaborg formulas and Royer's formulas of {alpha} decay.

  16. Methods and apparatus for producing and storing positrons and protons

    DOEpatents

    Akers, Douglas W [Idaho Falls, ID

    2010-07-06

    Apparatus for producing and storing positrons may include a trap that defines an interior chamber therein and that contains an electric field and a magnetic field. The trap may further include a source material that includes atoms that, when activated by photon bombardment, become positron emitters to produce positrons. The trap may also include a moderator positioned adjacent the source material. A photon source is positioned adjacent the trap so that photons produced by the photon source bombard the source material to produce the positron emitters. Positrons from the positron emitters and moderated positrons from the moderator are confined within the interior chamber of the trap by the electric and magnetic fields. Apparatus for producing and storing protons are also disclosed.

  17. Emissivity Tuned Emitter for RTPV Power Sources

    SciTech Connect

    Carl M. Stoots; Robert C. O'Brien; Troy M. Howe

    2012-03-01

    Every mission launched by NASA to the outer planets has produced unexpected results. The Voyager I and II, Galileo, and Cassini missions produced images and collected scientific data that totally revolutionized our understanding of the solar system and the formation of the planetary systems. These missions were enabled by the use of nuclear power. Because of the distances from the Sun, electrical power was produced using the radioactive decay of a plutonium isotope. Radioisotopic Thermoelectric Generators (RTGs) used in the past and currently used Multi-Mission RTGs (MMRTGs) provide power for space missions. Unfortunately, RTGs rely on thermocouples to convert heat to electricity and are inherently inefficient ({approx} 3-7% thermal to electric efficiency). A Radioisotope Thermal Photovoltaic (RTPV) power source has the potential to reduce the specific mass of the onboard power supply by increasing the efficiency of thermal to electric conversion. In an RTPV, a radioisotope heats an emitter, which emits light to a photovoltaic (PV) cell, which converts the light into electricity. Developing an emitter tuned to the desired wavelength of the photovoltaic is a key part in increasing overall performance. Researchers at the NASA Glenn Research Center (GRC) have built a Thermal Photovoltaic (TPV) system, that utilizes a simulated General Purpose Heat Source (GPHS) from a MMRTG to heat a tantalum emitter. The GPHS is a block of graphite roughly 10 cm by 10 cm by 5 cm. A fully loaded GPHS produces 250 w of thermal power and weighs 1.6 kgs. The GRC system relies on the GPHS unit radiating at 1200 K to a tantalum emitter that, in turn, radiates light to a GaInAs photo-voltaic cell. The GRC claims system efficiency of conversion of 15%. The specific mass is around 167 kg/kWe. A RTPV power source that utilized a ceramic or ceramic-metal (cermet) matrix would allow for the combination of the heat source, canister, and emitter into one compact unit, and allow variation in size

  18. Recombination processes in passivated boron-implanted black silicon emitters

    NASA Astrophysics Data System (ADS)

    von Gastrow, Guillaume; Ortega, Pablo; Alcubilla, Ramon; Husein, Sebastian; Nietzold, Tara; Bertoni, Mariana; Savin, Hele

    2017-05-01

    In this paper, we study the recombination mechanisms in ion-implanted black silicon (bSi) emitters and discuss their advantages over diffused emitters. In the case of diffusion, the large bSi surface area increases emitter doping and consequently Auger recombination compared to a planar surface. The total doping dose is on the contrary independent of the surface area in implanted emitters, and as a result, we show that ion implantation allows control of emitter doping without compromise in the surface aspect ratio. The possibility to control surface doping via implantation anneal becomes highly advantageous in bSi emitters, where surface passivation becomes critical due to the increased surface area. We extract fundamental surface recombination velocities Sn through numerical simulations and obtain the lowest values at the highest anneal temperatures. With these conditions, an excellent emitter saturation current (J0e) is obtained in implanted bSi emitters, reaching 20 fA/cm2 ± 5 fA/cm2 at a sheet resistance of 170 Ω/sq. Finally, we identify the different regimes of recombination in planar and bSi emitters as a function of implantation anneal temperature. Based on experimental data and numerical simulations, we show that surface recombination can be reduced to a negligible contribution in implanted bSi emitters, which explains the low J0e obtained.

  19. Proton maser

    NASA Astrophysics Data System (ADS)

    Ensley, D. L.

    1988-01-01

    New calculations are reported which confirm the ability of an a priori random, initial-phase proton beam to drive a simple, single-stage microwave cavity maser or transit-time oscillator (TTO) to saturation conversion efficiencies of about 11 percent. The required initial TE(011) mode field can be provided from beam ramp-up bandwidth of excitation to a low level from an external source. A saturation field of 45 tesla and output power of 0.2 TW are calculated using an electron insulation field of 10 tesla and a 3 MeV, 400 Ka/sq cm beam. Results are compared to those for an electron beam of the same energy and geometry, and it is shown that proton beams potentially can provide a three order of magnitude increase in overall microwave power production density over that obtainable from electron beam TTOs.

  20. Wavelength locking of single emitters and multi-emitter modules: simulation and experiments

    NASA Astrophysics Data System (ADS)

    Yanson, Dan; Rappaport, Noam; Peleg, Ophir; Berk, Yuri; Dahan, Nir; Klumel, Genady; Baskin, Ilya; Levy, Moshe

    2016-03-01

    Wavelength-stabilized high-brightness single emitters are commonly used in fiber-coupled laser diode modules for pumping Yb-doped lasers at 976 nm, and Nd-doped ones at 808 nm. We investigate the spectral behavior of single emitters under wavelength-selective feedback from a volume Bragg (or hologram) grating (VBG) in a multi-emitter module. By integrating a full VBG model as a multi-layer thin film structure with commercial raytracing software, we simulated wavelength locking conditions as a function of beam divergence and angular alignment tolerances. Good correlation between the simulated VBG feedback strength and experimentally measured locking ranges, in both VBG misalignment angle and laser temperature, is demonstrated. The challenges of assembling multi-emitter modules based on beam-stacked optical architectures are specifically addressed, where the wavelength locking conditions must be achieved simultaneously with high fiber coupling efficiency for each emitter in the module. It is shown that angular misorientation between fast and slow-axis collimating optics can have a dramatic effect on the spectral and power performance of the module. We report the development of our NEON-S wavelength-stabilized fiber laser pump module, which uses a VBG to provide wavelength-selective optical feedback in the collimated portion of the beam. Powered by our purpose-developed high-brightness single emitters, the module delivers 47 W output at 11 A from an 0.15 NA fiber and a 0.3 nm linewidth at 976 nm. Preliminary wavelength-locking results at 808 nm are also presented.

  1. Delay modeling of bipolar ECL/EFL (Emitter-Coupled Logic/Emitter-Follower-Logic) circuits

    NASA Astrophysics Data System (ADS)

    Yang, Andrew T.

    1986-08-01

    This report deals with the development of a delay-time model for timing simulation of large circuits consisting of Bipolar ECL(Emitter-Coupled Logic) and EFL (Emitter-Follower-Logic) networks. This model can provide adequate information on the performance of the circuits with a minimum expenditure of computation time. This goal is achieved by the use of proper circuit transient models on which analytical delay expressions can be derived with accurate results. The delay-model developed in this report is general enough to handle complex digital circuits with multiple inputs or/and multiple levels. The important effects of input slew rate are also included in the model.

  2. Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

  3. The Quantum Efficiency and Thermal Emittance of Metal Photocathodes

    SciTech Connect

    Dowell, David H.; Schmerge, John F.; /SLAC

    2009-03-04

    Modern electron beams have demonstrated the brilliance needed to drive free electron lasers at x-ray wavelengths, with the principle improvements occurring since the invention of the photocathode gun. The state-of-the-art normalized emittance electron beams are now becoming limited by the thermal emittance of the cathode. In both DC and RF photocathode guns, details of the cathode emission physics strongly influence the quantum efficiency and the thermal emittance. Therefore improving cathode performance is essential to increasing the brightness of beams. It is especially important to understand the fundamentals of cathode quantum efficiency and thermal emittance. This paper investigates the relationship between the quantum efficiency and the thermal emittance of metal cathodes using the Fermi-Dirac model for the electron distribution. We derive the thermal emittance and its relationship to the quantum efficiency, and compare our results to those of others.

  4. Emittance measurements of Space Shuttle orbiter reinforced carbon-carbon

    NASA Technical Reports Server (NTRS)

    Caram, Jose M.; Bouslog, Stanley A.; Cunnington, George R., Jr.

    1992-01-01

    The spectral and total normal emittance of the Reinforced Carbon-Carbon (RCC) used on Space Shuttle nose cap and wing leading edges has been measured at room temperature and at surface temperatures of 1200 to 2100 K. These measurements were made on virgin and two flown RCC samples. Room temperature directional emittance data were also obtained and were used to determine the total hemispherical emittance of RCC as a function of temperature. Results of the total normal emittance for the virgin samples showed good agreement with the current RCC emittance design curve; however, the data from the flown samples showed an increase in the emittance at high temperature possibly due to exposure from flight environments.

  5. Characterization of radiant emitters used in food processing.

    PubMed

    Lloyd, B J; Farkas, B E; Keener, K M

    2003-01-01

    Radiant emissions from short, medium, and long wavelength thermal radiant emitter systems typically used for food processing applications were quantified. Measurements included heat flux intensity, emitter surface temperature, and spectral wavelength distribution. Heat flux measurements were found highly dependent on the incident angle and the distance from the emitter facing. The maximum flux measured was 5.4 W/cm2. Emitter surface temperature measurements showed that short wavelength radiant systems had the highest surface temperature and greatest thermal efficiency. The emitter spectral distributions showed that radiant emitter systems had large amounts of far infrared energy emission greater than 3 microm when compared to theoretical blackbody curves. The longer wavelength energy would likely cause increased surface heating for most high moisture content food materials.

  6. Plasmonic superradiance of two emitters near a metal nanorod

    NASA Astrophysics Data System (ADS)

    Protsenko, I. E.; Uskov, A. V.; Chen, Xue-Wen; Xu, Hongxing

    2017-06-01

    Quantum emitters, such as quantum dots or dye molecules, pumped and situated close to plasmonic nanostructures resonantly excite surface plasmon-polaritons (SPPs). Excitation efficiency increases with the number of emitters because the SPP field synchronizes dipole oscillations of emitters, in analogy with superradiance (SR) in free space. Using a fully quantum mechanical model for two emitters coupled to a single metal nanorod, we predict that plasmonic SR increases the SPP generation yield of a single emitter by up to 15%. Such ‘plasmonic SR’ enhancement of SPP generation is stationary and takes place even at strong dissipation, dephasing and under incoherent pumping. Solid-state quantum emitters with blinking behaviors may be used to demonstrate plasmonic SR. Plasmonic SR may be useful for excitation of non-radiative SPP modes in plasmonic waveguides and lowering the threshold of plasmonic nanolasers.

  7. Active spacecraft potential control: An ion emitter experiment. [Cluster mission

    NASA Technical Reports Server (NTRS)

    Riedler, W.; Goldstein, R.; Hamelin, M.; Maehlum, B. N.; Troim, J.; Olsen, R. C.; Pedersen, A.; Grard, R. J. L.; Schmidt, R.; Rudenauer, F.

    1988-01-01

    The cluster spacecraft are instrumented with ion emitters for charge neutralization. The emitters produce indium ions at 6 keV. The ion current is adjusted in a feedback loop with instruments measuring the spacecraft potential. The system is based on the evaporation of indium in the apex field of a needle. The design of the active spacecraft potential control instruments, and the ion emitters is presented.

  8. Separation of temperature and emittance in remotely sensed radiance measurements

    NASA Technical Reports Server (NTRS)

    Kahle, Anne B.; Alley, Ronald E.

    1992-01-01

    The remote determination of surface temperature and surface spectral emittance by use of airborne or satellite-borne thermal infrared instruments is not straightforward. The radiance measured is a function of surface temperature, the unknown surface spectral emittance, and absorption and emission in the intervening atmosphere. With a single measurement, the solution for temperature and spectral emittance is undedetermined. This article reviews two of the early approximate methods which have been fairly widely used to approach this problem.

  9. Thermal emittance measurements of a cesium potassium antimonide photocathode

    NASA Astrophysics Data System (ADS)

    Bazarov, Ivan; Cultrera, Luca; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Li, Yulin; Liu, Xianghong; Maxson, Jared; Roussel, William

    2011-05-01

    Thermal emittance measurements of a CsK2Sb photocathode at several laser wavelengths are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. The thermal emittance is 0.56±0.03 mm mrad/mm(rms) at 532 nm wavelength. The results are compared with a simple photoemission model and found to be in a good agreement.

  10. Sub-nm emittance lattice design for CANDLE storage ring

    NASA Astrophysics Data System (ADS)

    Sargsyan, A.; Zanyan, G.; Sahakyan, V.; Tsakanov, V.

    2016-10-01

    The most effective way to increase the brilliance of synchrotron light sources is the reduction of beam emittance. Following the recent developments in low emittance lattice design, a new sub-nm emittance lattice based on implementation of multi-band achromat concept and application of longitudinal gradient bending magnets was developed for CANDLE storage ring. The paper presents the main design considerations, linear and non-linear beam dynamics aspects of the new lattice proposed.

  11. Emittance calculations for the Stanford Linear Collider injector

    SciTech Connect

    Sheppard, J.C.; Clendenin, J.E.; Helm, R.H.; Lee, M.J.; Miller, R.H.; Blocker, C.A.

    1983-03-01

    A series of measurements have been performed to determine the emittance of the high intensity, single bunch beam that is to be injected into the Stanford Linear Collider. On-line computer programs were used to control the Linac for the purpose of data acquisition and to fit the data to a model in order to deduce the beam emittance. This paper will describe the method of emittance calculation and present some of the measurement results.

  12. Environmental awareness for sensor and emitter employment

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kenneth K.; Wilson, D. Keith

    2010-04-01

    Environmental Awareness for Sensor and Emitter Employment (EASEE) is a flexible, object-oriented software design for predicting environmental effects on the performance of battlefield sensors and detectability of signal emitters. Its decision-support framework facilitates many sensor and emitter modalities and can be incorporated into battlespace command and control (C2) systems. Other potential applications include immersive simulation, force-on-force simulation, and virtual prototyping of sensor systems and signal-processing algorithms. By identifying and encoding common characteristics of Army problems involving multimodal signal transmission and sensing into a flexible software architecture in the Java programming language, EASEE seeks to provide an application interface enabling rapid integration of diverse signal-generation, propagation, and sensor models that can be implemented in many client-server environments. Its explicit probabilistic modeling of signals, systematic consideration of many complex environmental and mission-related factors affecting signal generation and propagation, and computation of statistical metrics characterizing sensor performance facilitate a highly flexible approach to signal modeling and simulation. EASEE aims to integrate many disparate statistical formulations for modeling and processing many types of signals, including infrared, acoustic, seismic, radiofrequency, and chemical/biological. EASEE includes objects for representing sensor data, inferences for target detection and/or direction, signal transmission and processing, and state information (such as time and place). Various transmission and processing objects are further grouped into platform objects, which fuse data to make various probabilistic predictions of interest. Objects representing atmospheric and terrain environments with varying degrees of fidelity enable modeling of signal generation and propagation in diverse and complex environments.

  13. Infrared spectral normal emittance/emissivity comparison

    NASA Astrophysics Data System (ADS)

    Hanssen, L.; Wilthan, B.; Filtz, J.-R.; Hameury, J.; Girard, F.; Battuello, M.; Ishii, J.; Hollandt, J.; Monte, C.

    2016-01-01

    The National Measurement Institutes (NMIs) of the United States, Germany, France, Italy and Japan, have joined in an inter-laboratory comparison of their infrared spectral emittance scales. This action is part of a series of supplementary inter-laboratory comparisons (including thermal conductivity and thermal diffusivity) sponsored by the Consultative Committee on Thermometry (CCT) Task Group on Thermophysical Quantities (TG-ThQ). The objective of this collaborative work is to strengthen the major operative National Measurement Institutes' infrared spectral emittance scales and consequently the consistency of radiative properties measurements carried out worldwide. The comparison has been performed over a spectral range of 2 μm to 14 μm, and a temperature range from 23 °C to 800 °C. Artefacts included in the comparison are potential standards: oxidized Inconel, boron nitride, and silicon carbide. The measurement instrumentation and techniques used for emittance scales are unique for each NMI, including the temperature ranges covered as well as the artefact sizes required. For example, all three common types of spectral instruments are represented: dispersive grating monochromator, Fourier transform and filter-based spectrometers. More than 2000 data points (combinations of material, wavelength and temperature) were compared. Ninety-eight percent (98%) of the data points were in agreement, with differences to weighted mean values less than the expanded uncertainties calculated from the individual NMI uncertainties and uncertainties related to the comparison process. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  14. Emittance and energy control in the NLC main linacs

    SciTech Connect

    Adolphsen, C.; Bane, K.L.F.; Kubo, K.; Raubenheimer, T.; Ruth, R.D.; Thompson, K.A.; Zimmermann, F.

    1995-06-01

    The authors discuss tolerances and correction schemes needed to control single- and multi-bunch emittance in the NLC main linacs. Specifications and design of emittance diagnostic stations will be presented. Trajectory correction schemes appropriate to simultaneously controlling the emittance of a multibunch train and the emittance of individual bunches within the train will be discussed. The authors discuss control of bunch-to-bunch energy spread using a ramped RF pulse generated by phase-modulating the SLED-II input. Tolerances on ions, wake fields, quadrupole alignment, and accelerating structure alignment will be given.

  15. Analysis of Slice Transverse Emittance Evolution ina Photocathode RF Gun

    SciTech Connect

    Huang, Z.; Ding, Y.; Qiang, J.; /LBL, Berkeley

    2007-10-17

    The slice transverse emittance of an electron beam is of critical significance for an x-ray FEL. In a photocathode RF gun, the slice transverse emittance is not only determined by the emission process, but also influenced strongly by the non-linear space charge effect. In this paper, we study the slice transverse emittance evolution in a photocathode RF gun using a simple model that includes effects of RF acceleration, focusing, and space charge force. The results are compared with IMPACT-T space charge simulations and may be used to understand the development of the slice emittance in an RF gun.

  16. Theoretical study of transverse-longitudinal emittance coupling

    SciTech Connect

    Qin, H; Davidson, R C; Chung, M; Barnard, J J; Wang, T F

    2011-04-14

    The effect of a weakly coupled periodic lattice in terms of achieving emittance exchange between the transverse and longitudinal directions is investigated using the generalized Courant-Snyder theory for coupled lattices. Recently, the concept and technique of transverse-longitudinal emittance coupling have been proposed for applications in the Linac Coherent Light Source and other free-electron lasers to reduce the transverse emittance of the electron beam. Such techniques can also be applied to the driver beams for the heavy ion fusion and beam-driven high energy density physics, where the transverse emittance budget is typically tighter than the longitudinal emittance. The proposed methods consist of one or several coupling components which completely swap the emittances of one of the transverse directions and the longitudinal direction at the exit of the coupling components. The complete emittance exchange is realized in one pass through the coupling components. In the present study, we investigate the effect of a weakly coupled periodic lattice in terms of achieving emittance exchange between the transverse and longitudinal directions. A weak coupling component is introduced at every focusing lattice, and we would like to determine if such a lattice can realize the function of emittance exchange.

  17. Efficient low-temperature thermophotovoltaic emitters from metallic photonic crystals.

    PubMed

    Nagpal, Prashant; Han, Sang Eon; Stein, Andreas; Norris, David J

    2008-10-01

    We examine the use of metallic photonic crystals as thermophotovoltaic emitters. We coat silica woodpile structures, created using direct laser writing, with tungsten or molybdenum. Optical reflectivity and thermal emission measurements near 650 degrees C demonstrate that the resulting structures should provide efficient emitters at relatively low temperatures. When matched to InGaAsSb photocells, our structures should generate over ten times more power than solid emitters while having an optical-to-electrical conversion efficiency above 32%. At such low temperatures, these emitters have promise not only in solar energy but also in harnessing geothermal and industrial waste heat.

  18. Injection of large transverse emittance EBIS beams in booster

    SciTech Connect

    Gardner, C.

    2011-10-10

    During the commissioning of EBIS beams in Booster in November 2010 and in April, May and June 2011, it was found that the transverse emittances of the EBIS beams just upstream of Booster were much larger than expected. Beam emittances of 11{pi} mm milliradians had been expected, but numbers 3 to 4 times larger were measured. Here and throughout this note the beam emittance, {pi}{epsilon}{sub 0}, is taken to be the area of the smallest ellipse that contains 95% of the beam. We call this smallest ellipse the beam ellipse. If the beam distribution is gaussian, the rms emittance of the distribution is very nearly one sixth the area of the beam ellipse. The normalized rms emittance is the rms emittance times the relativistic factor {beta}{gamma} = 0.06564. This amounts to 0.12{pi} mm milliradians for the 11{pi} mm milliradian beam ellipse. In [1] we modeled the injection and turn-by-turn evolution of an 11{pi} mm milliradian beam ellipse in the horizontal plane in Booster. It was shown that with the present injection system, up to 4 turns of this beam could be injected and stored in Booster without loss. In the present note we extend this analysis to the injection of larger emittance beams. We consider only the emittance in the horizontal plane. Emittance in the vertical plane and the effects of dispersion are treated in [2].

  19. Proton scaling

    SciTech Connect

    Canavan, Gregory H

    2009-01-01

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

  20. Multi-channel polarized thermal emitter

    DOEpatents

    Lee, Jae-Hwang; Ho, Kai-Ming; Constant, Kristen P

    2013-07-16

    A multi-channel polarized thermal emitter (PTE) is presented. The multi-channel PTE can emit polarized thermal radiation without using a polarizer at normal emergence. The multi-channel PTE consists of two layers of metallic gratings on a monolithic and homogeneous metallic plate. It can be fabricated by a low-cost soft lithography technique called two-polymer microtransfer molding. The spectral positions of the mid-infrared (MIR) radiation peaks can be tuned by changing the periodicity of the gratings and the spectral separation between peaks are tuned by changing the mutual angle between the orientations of the two gratings.

  1. High efficiency quasi-monochromatic infrared emitter

    NASA Astrophysics Data System (ADS)

    Brucoli, Giovanni; Bouchon, Patrick; Haïdar, Riad; Besbes, Mondher; Benisty, Henri; Greffet, Jean-Jacques

    2014-02-01

    Incandescent radiation sources are widely used as mid-infrared emitters owing to the lack of alternative for compact and low cost sources. A drawback of miniature hot systems such as membranes is their low efficiency, e.g., for battery powered systems. For targeted narrow-band applications such as gas spectroscopy, the efficiency is even lower. In this paper, we introduce design rules valid for very generic membranes demonstrating that their energy efficiency for use as incandescent infrared sources can be increased by two orders of magnitude.

  2. High efficiency quasi-monochromatic infrared emitter

    SciTech Connect

    Brucoli, Giovanni; Besbes, Mondher; Benisty, Henri Greffet, Jean-Jacques; Bouchon, Patrick; Haïdar, Riad

    2014-02-24

    Incandescent radiation sources are widely used as mid-infrared emitters owing to the lack of alternative for compact and low cost sources. A drawback of miniature hot systems such as membranes is their low efficiency, e.g., for battery powered systems. For targeted narrow-band applications such as gas spectroscopy, the efficiency is even lower. In this paper, we introduce design rules valid for very generic membranes demonstrating that their energy efficiency for use as incandescent infrared sources can be increased by two orders of magnitude.

  3. Multiple emitter location and signal parameter estimation

    NASA Astrophysics Data System (ADS)

    Schmidt, R. O.

    1986-03-01

    Multiple signal classification (MUSIC) techniques involved in determining the parameters of multiple wavefronts arriving at an antenna array are discussed. A MUSIC algorithm is described, which provides asymptotically unbiased estimates of (1) the number of signals, (2) directions of arrival (or emitter locations), (3) strengths and cross correlations among the incident waveforms, and (4) the strength of noise/interference. The example of the use of the algorithm as a multiple frequency estimator operating on time series is examined. Comparisons of this method with methods based on maximum likelihood and maximum entropy, as well as conventional beamforming, are presented.

  4. Emittance growth from transient coherent synchrotron radiation

    SciTech Connect

    Bohn, C.L.; Li, R.; Bisognano, J.J.

    1996-10-01

    If the energies of individual particles in a bunch change as the bunch traverses a bending system, even if it is achromatic, betatron oscillations can be excited. Consequently, the transverse emittance of the bunch will grow as it moves downstream. Short bunches may be particularly susceptible to emission of coherent synchrotron radiation which can act back on the particles to change their energies and trajectories. Because a bend spans a well-defined length and angle, the bunch-excited wakefield and its effect back on the bunch are inherently transient. We outline a recently developed theory of this effect and apply it to example bending systems.

  5. Monitoring airborne alpha-emitter contamination

    SciTech Connect

    Kerr, P.L.; Koster, J.E.; Conaway, J.G.; Bounds, J.A.; Whitley, C.W.; Steadman, P.A.

    1998-02-01

    Facilities that may produce airborne alpha emitter contamination require a continuous air monitoring (CAM) system. However, these traditional CAMs have difficulty in environments with large quantities of non-radioactive particulates such as dust and salt. Los Alamos has developed an airborne plutonium sensor (APS) for the REBOUND experiment at the Nevada Test Site which detects alpha contamination directly in the air, and so is less vulnerable to the problems associated with counting activity on a filter. In addition, radon compensation is built into the detector by the use of two measurement chambers.

  6. Two-Proton Radioactivity of ^{67}Kr.

    PubMed

    Goigoux, T; Ascher, P; Blank, B; Gerbaux, M; Giovinazzo, J; Grévy, S; Kurtukian Nieto, T; Magron, C; Doornenbal, P; Kiss, G G; Nishimura, S; Söderström, P-A; Phong, V H; Wu, J; Ahn, D S; Fukuda, N; Inabe, N; Kubo, T; Kubono, S; Sakurai, H; Shimizu, Y; Sumikama, T; Suzuki, H; Takeda, H; Agramunt, J; Algora, A; Guadilla, V; Montaner-Piza, A; Morales, A I; Orrigo, S E A; Rubio, B; Fujita, Y; Tanaka, M; Gelletly, W; Aguilera, P; Molina, F; Diel, F; Lubos, D; de Angelis, G; Napoli, D; Borcea, C; Boso, A; Cakirli, R B; Ganioglu, E; Chiba, J; Nishimura, D; Oikawa, H; Takei, Y; Yagi, S; Wimmer, K; de France, G; Go, S; Brown, B A

    2016-10-14

    In an experiment with the BigRIPS separator at the RIKEN Nishina Center, we observed two-proton (2p) emission from ^{67}Kr. At the same time, no evidence for 2p emission of ^{59}Ge and ^{63}Se, two other potential candidates for this exotic radioactivity, could be observed. This observation is in line with Q value predictions which pointed to ^{67}Kr as being the best new candidate among the three for two-proton radioactivity. ^{67}Kr is only the fourth 2p ground-state emitter to be observed with a half-life of the order of a few milliseconds. The decay energy was determined to be 1690(17) keV, the 2p emission branching ratio is 37(14)%, and the half-life of ^{67}Kr is 7.4(30) ms.

  7. Two-Proton Radioactivity of 67Kr

    NASA Astrophysics Data System (ADS)

    Goigoux, T.; Ascher, P.; Blank, B.; Gerbaux, M.; Giovinazzo, J.; Grévy, S.; Kurtukian Nieto, T.; Magron, C.; Doornenbal, P.; Kiss, G. G.; Nishimura, S.; Söderström, P.-A.; Phong, V. H.; Wu, J.; Ahn, D. S.; Fukuda, N.; Inabe, N.; Kubo, T.; Kubono, S.; Sakurai, H.; Shimizu, Y.; Sumikama, T.; Suzuki, H.; Takeda, H.; Agramunt, J.; Algora, A.; Guadilla, V.; Montaner-Piza, A.; Morales, A. I.; Orrigo, S. E. A.; Rubio, B.; Fujita, Y.; Tanaka, M.; Gelletly, W.; Aguilera, P.; Molina, F.; Diel, F.; Lubos, D.; de Angelis, G.; Napoli, D.; Borcea, C.; Boso, A.; Cakirli, R. B.; Ganioglu, E.; Chiba, J.; Nishimura, D.; Oikawa, H.; Takei, Y.; Yagi, S.; Wimmer, K.; de France, G.; Go, S.; Brown, B. A.

    2016-10-01

    In an experiment with the BigRIPS separator at the RIKEN Nishina Center, we observed two-proton (2 p ) emission from 67Kr. At the same time, no evidence for 2 p emission of 59Ge and 63Se, two other potential candidates for this exotic radioactivity, could be observed. This observation is in line with Q value predictions which pointed to 67Kr as being the best new candidate among the three for two-proton radioactivity. 67Kr is only the fourth 2 p ground-state emitter to be observed with a half-life of the order of a few milliseconds. The decay energy was determined to be 1690(17) keV, the 2 p emission branching ratio is 37(14)%, and the half-life of 67Kr is 7.4(30) ms.

  8. Barium depletion in hollow cathode emitters

    NASA Astrophysics Data System (ADS)

    Polk, James E.; Mikellides, Ioannis G.; Capece, Angela M.; Katz, Ira

    2016-01-01

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al2O3 source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  9. Barium depletion in hollow cathode emitters

    SciTech Connect

    Polk, James E. Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2016-01-14

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al{sub 2}O{sub 3} source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values.

  10. Micro-electrospray with stainless steel emitters.

    PubMed

    Shui, Wenqing; Yu, Yanling; Xu, Xuejiao; Huang, Zhenyu; Xu, Guobing; Yang, Pengyuan

    2003-01-01

    The physical processes underlying micro-electrospray (micro-ES) performance were investigated using a stainless steel (SS) emitter with a blunt tip. Sheathless micro-ES could be generated at a blunt SS tip without any tapering or sanding if ESI conditions were optimized. The Taylor cone was found to shrink around the inner diameter of the SS tubing, which permitted a low flow rate of 150 nL/min for sheathless microspray on the blunt tip (100 microm i.d. x 400 microm o.d.). It is believed that the wettability and/or hydrophobicity of SS tips are responsible for their micro-ES performance. The outlet orifice was further nipped to reduce the size of the spray cone and limit the flow rate to 50-150 nL/min, resulting in peptide detection down to attomole quantities consumed per spectrum. The SS emitter was also integrated into a polymethylmethacrylate microchip and demonstrated satisfactory performance in the analysis and identification of a myoglobin digest.

  11. Muon Emittance Exchange with a Potato Slicer

    SciTech Connect

    Summers, D. J.; Hart, T. L.; Acosta, J. G.; Cremaldi, L. M.; Oliveros, S. J.; Perera, L. P.; Neuffer, D. V.

    2015-04-15

    We propose a novel scheme for final muon ionization cooling with quadrupole doublets followed by emittance exchange in vacuum to achieve the small beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized transverse, longitudinal, and angular momentum emittances of 0.100, 2.5, and 0.200 mm-rad are exchanged into 0.025, 70, and 0.0 mm-rad. A skew quadrupole triplet transforms a round muon bunch with modest angular momentum into a flat bunch with no angular momentum. Thin electrostatic septa efficiently slice the flat bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 µs, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift in the ring until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87 %.

  12. Compact Rare Earth Emitter Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  13. Group-III Nitride Field Emitters

    NASA Technical Reports Server (NTRS)

    Bensaoula, Abdelhak; Berishev, Igor

    2008-01-01

    Field-emission devices (cold cathodes) having low electron affinities can be fabricated through lattice-mismatched epitaxial growth of nitrides of elements from group III of the periodic table. Field emission of electrons from solid surfaces is typically utilized in vacuum microelectronic devices, including some display devices. The present field-emission devices and the method of fabricating them were developed to satisfy needs to reduce the cost of fabricating field emitters, make them compatible with established techniques for deposition of and on silicon, and enable monolithic integration of field emitters with silicon-based driving circuitry. In fabricating a device of this type, one deposits a nitride of one or more group-III elements on a substrate of (111) silicon or other suitable material. One example of a suitable deposition process is chemical vapor deposition in a reactor that contains plasma generated by use of electron cyclotron resonance. Under properly chosen growth conditions, the large mismatch between the crystal lattices of the substrate and the nitride causes strains to accumulate in the growing nitride film, such that the associated stresses cause the film to crack. The cracks lie in planes parallel to the direction of growth, so that the growing nitride film becomes divided into microscopic growing single-crystal columns. The outer ends of the fully-grown columns can serve as field-emission tips. By virtue of their chemical compositions and crystalline structures, the columns have low work functions and high electrical conductivities, both of which are desirable for field emission of electrons. From examination of transmission electron micrographs of a prototype device, the average column width was determined to be about 100 nm and the sharpness of the tips was determined to be characterized by a dimension somewhat less than 100 nm. The areal density of the columns was found to about 5 x 10(exp 9)/sq cm . about 4 to 5 orders of magnitude

  14. Measurement of proton-induced target fragmentation cross sections in carbon

    NASA Astrophysics Data System (ADS)

    Matsushita, K.; Nishio, T.; Tanaka, S.; Tsuneda, M.; Sugiura, A.; Ieki, K.

    2016-02-01

    In proton therapy, positron emitter nuclei are generated via the target nuclear fragmentation reactions between irradiated proton and nuclei constituting a human body. The proton-irradiated volume can be confirmed with measurement of annihilation γ-rays from the generated positron emitter nuclei. To achieve the high accuracy of proton therapy, in vivo dosimetry, i.e., evaluation of the irradiated dose during the treatment is important. To convert the measured activity distribution to irradiated dose, cross-sectional data for positron emitter production is necessary, which is currently insufficient in the treatment area. The purpose of this study is to collect cross-sectional data of 12C (p , pn)11C and 12C (p , p 2 n)10C reactions between the incident proton and carbon nuclei, which are important target nuclear fragmentation reactions, to estimate the range and exposure dose distribution in the patient's body. Using planar-type PET capable of measuring annihilation γ-rays at high positional resolution and thick polyethylene target, we measured cross-sectional data in continuous wide energy range. The cross section of 12C (p , pn)11C is in good agreement with existing experimental data. The cross section of 12C (p , p 2 n)10C is reported for the first data in the low-energy range of 67.6-10.5 MeV near the Bragg peak of proton beam.

  15. Emittance growth due to negative-mass instability above transition

    SciTech Connect

    Ng, King-Yuen

    1994-08-01

    Due to space-charge effect, there is a growth of bunch emittance across transition as a result of negative-mass instability. The models of growth at cutoff frequency and growth from high-frequency Schottky noise are reviewed. The difficulties of performing reliable simulations are discussed. An intuitive self-bunching model for estimating emittance growth is presented.

  16. Emittance growth due to dipole ripple and sextupole

    SciTech Connect

    Shih, H.J.; Ellison, J.A.; Syphers, M.J.; Newberger, B.S.

    1993-05-01

    Ripple in the power supplies for storage ring magnets can have adverse effects on the circulating beams: orbit distortion and emittance growth from dipole ripple, tune modulation and dynamic aperture reduction from quadrupole ripple, etc. In this paper, we study the effects of ripple in the horizontal bending field of the SSC in the presence of nonlinearity, in particular, the growth in beam emittance.

  17. Close proximity electrostatic effect from small clusters of emitters

    NASA Astrophysics Data System (ADS)

    Dall’Agnol, Fernando F.; de Assis, Thiago A.

    2017-10-01

    Using a numerical simulation based on the finite-element technique, this work investigates the field emission properties from clusters of a few emitters at close proximity, by analyzing the properties of the maximum local field enhancement factor (γm ) and the corresponding emission current. At short distances between the emitters, we show the existence of a nonintuitive behavior, which consists of the increasing of γm as the distance c between the emitters decreases. Here we investigate this phenomenon for clusters with 2, 3, 4 and 7 identical emitters and study the influence of the proximity effect in the emission current, considering the role of the aspect ratio of the individual emitters. Importantly, our results show that peripheral emitters with high aspect-ratios in large clusters can, in principle, significantly increase the emitted current as a consequence only of the close proximity electrostatic effect (CPEE). This phenomenon can be seen as a physical mechanism to produce self-oscillations of individual emitters. We discuss new insights for understanding the nature of self-oscillations in emitters based on the CPEE, including applications to nanometric oscillators.

  18. Surface Coatings for Low Emittance in the Thermal Surveillance Band

    DTIC Science & Technology

    1984-08-01

    transparent but conducting coatings on glass [4] and (3) the solar energy industry , where surface coatings are required for solar collectors which...increase in coating emittance [10]. 0 Research into low emittance paint is mainly carried out in the solar energy industry [11, 12] and can be

  19. Spectral beam combining of multi-single emitters

    NASA Astrophysics Data System (ADS)

    Wang, Baohua; Guo, Weirong; Guo, Zhijie; Xu, Dan; Zhu, Jing; Zhang, Qiang; Yang, Thomas; Chen, Xiaohua

    2016-03-01

    Spectral beam combination expands the output power while keeps the beam quality of the combined beam almost the same as that of a single emitter. Spectral beam combination has been successfully achieved for high power fiber lasers, diode laser arrays and diode laser stacks. We have recently achieved the spectral beam combination of multiple single emitter diode lasers. Spatial beam combination and beam transformation are employed before beams from 25 single emitter diode lasers can be spectrally combined. An average output power about 220W, a spectral bandwidth less than 9 nm (95% energy), a beam quality similar to that of a single emitter and electro-optical conversion efficiency over 46% are achieved. In this paper, Rigorous Coupled Wave analysis is used to numerically evaluate the influence of emitter width, emitter pitch and focal length of transform lens on diffraction efficiency of the grating and spectral bandwidth. To assess the chance of catastrophic optical mirror damage (COMD), the optical power in the internal cavity of a free running emitter and the optical power in the grating external cavity of a wavelength locked emitter are theoretically analyzed. Advantages and disadvantages of spectral beam combination are concluded.

  20. Experimental Results of a Single Emittance Compensation Solenoidal Magnet

    NASA Astrophysics Data System (ADS)

    Palmer, D. T.; Wang, X. J.; Ben-Zvi, I.; Miller, R. H.; Skaritka, J.

    1997-05-01

    A new iron dominated single emittance compensation solenoidal magnet was designed to be integrated with the BNL/SLAC/UCLA 1.6 cell S-Band Photocathode RF Gun. This emittance compensated photoinjector is now in operation at the Brookhaven Accelerator Test Facility. It has produced a 300 pC electron bunches with a normalized rms transverse emittance of ɛ_n,rms = 0.7 π mm mrad. POISSON field maps were used with PARMELA to optimize the emittance compensation solenoidal magnet design. Magnetic field measurements show that at the cathode plane Bz <= 10 gauss for a peak magnetic field of B_z,max = 3 KG. Which is in agreement with POISSON simulation. A single emittance compensation solenoidal magnet will produces a initial angular momentum of the electron bunch that manifests itself in a initial magnetic emittance term that cannot be eliminated. This magnetic emittance ɛ_mag,n,rms scales as 0.01 π mm mrad per gauss at the cathode. Which is in agreement with PARMELA simulations. Experimental beam dynamics results are presented that show spot size and emittance as a function of cathode magnetic field. These results are compared to theory and simulations.

  1. Sharpening of field emitter tips using high-energy ions

    DOEpatents

    Musket, Ronald G.

    1999-11-30

    A process for sharpening arrays of field emitter tips of field emission cathodes, such as found in field-emission, flat-panel video displays. The process uses sputtering by high-energy (more than 30 keV) ions incident along or near the longitudinal axis of the field emitter to sharpen the emitter with a taper from the tip or top of the emitter down to the shank of the emitter. The process is particularly applicable to sharpening tips of emitters having cylindrical or similar (e.g., pyramidal) symmetry. The process will sharpen tips down to radii of less than 12 nm with an included angle of about 20 degrees. Because the ions are incident along or near the longitudinal axis of each emitter, the tips of gated arrays can be sharpened by high-energy ion beams rastered over the arrays using standard ion implantation equipment. While the process is particularly applicable for sharpening of arrays of field emitters in field-emission flat-panel displays, it can be effectively utilized in the fabrication of other vacuum microelectronic devices that rely on field emission of electrons.

  2. Microfabricated emitter array for an ionic liquid electrospray thruster

    NASA Astrophysics Data System (ADS)

    Nakagawa, Kaito; Tsuchiya, Toshiyuki; Takao, Yoshinori

    2017-06-01

    We have fabricated needle-shaped emitters on a Si wafer by a MEMS process, and measured the voltage-current characteristics and the frequency dependence of a bipolar pulse voltage for ionic liquid electrospray thrusters, which can be mounted on nanosatellites ( ≲ 10 kg). Although the extracted current did not increase with increasing number of emitters, probably owing to the lack of uniformity of the emitters fabricated, we have demonstrated that the emitted current depends on the gap distance between the emitter and the extractor grid electrode, and low frequencies of the bipolar pulse voltage are desirable for thruster operation. Moreover, the Bosch process is required for fabricating a reservoir of ionic liquid, which prevents undesirable electrical short circuits, and the minimum emitter pitch to prevent loss of ion beams to the extractor is estimated to be about 400 µm.

  3. Power flow from a dipole emitter near an optical antenna.

    PubMed

    Huang, Kevin C Y; Jun, Young Chul; Seo, Min-Kyo; Brongersma, Mark L

    2011-09-26

    Current methods to calculate the emission enhancement of a quantum emitter coupled to an optical antenna of arbitrary geometry rely on analyzing the total Poynting vector power flow out of the emitter or the dyadic Green functions from full-field numerical simulations. Unfortunately, these methods do not provide information regarding the nature of the dominant energy decay pathways. We present a new approach that allows for a rigorous separation, quantification, and visualization of the emitter output power flow captured by an antenna and the subsequent reradiation power flow to the far field. Such analysis reveals unprecedented details of the emitter/antenna coupling mechanisms and thus opens up new design strategies for strongly interacting emitter/antenna systems used in sensing, active plasmonics and metamaterials, and quantum optics.

  4. Transit time and charge storage measurements in heavily doped emitters

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Park, J. S.; Hwang, B. Y.

    1986-01-01

    A first direct measurement of the minority-carrier transit time in a transparent heavily doped emitter layer is reported. The value was obtained by a high-frequency conductance method recently developed and used for low-doped Si. The transit time coupled with the steady-state current enables the determination of the quasi-static charge stored in the emitter and the quasi-static emitter capacitance. Using a transport model, from the measured transit time, the value for the minority-carrier diffusion coefficient and mobility is estimated. The measurements were done using a heavily doped emitter of the Si p(+)-n-p bipolar transistor. The new result indicates that the position-averaged minority-carrier diffusion coefficients may be much smaller than the corresponding majority-carrier values for emitters having a concentration ranging from about 3 x 10 to the 19th per cu cm to 10 to the 20th per cu cm.

  5. Radiative performance of rare earth garnet thin film selective emitters

    SciTech Connect

    Lowe, R.A.; Chubb, D.L.; Good, B.S.

    1994-08-01

    In this paper the authors present the first emitter efficiency results for the thin film 40 percent Er-1.5 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) and 25 percent Ho YAG selective emitter at 1500 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns). Emitter efficiency and power density are significantly improved with the addition of multiple rare earth dopants. Predicted efficiency results are presented for an optimized (equal power density in the Er, (4)I[sub 15/2]-(4)I[sub 13/2] at 1.5 microns, and Ho, (5)I[sub 7]-(5)I[sub 8] at 2.0 micron emission bands) Er-Ho YAG thin film selective emitter.

  6. Transit time and charge storage measurements in heavily doped emitters

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Park, J. S.; Hwang, B. Y.

    1986-01-01

    A first direct measurement of the minority-carrier transit time in a transparent heavily doped emitter layer is reported. The value was obtained by a high-frequency conductance method recently developed and used for low-doped Si. The transit time coupled with the steady-state current enables the determination of the quasi-static charge stored in the emitter and the quasi-static emitter capacitance. Using a transport model, from the measured transit time, the value for the minority-carrier diffusion coefficient and mobility is estimated. The measurements were done using a heavily doped emitter of the Si p(+)-n-p bipolar transistor. The new result indicates that the position-averaged minority-carrier diffusion coefficients may be much smaller than the corresponding majority-carrier values for emitters having a concentration ranging from about 3 x 10 to the 19th per cu cm to 10 to the 20th per cu cm.

  7. Evaluations of carbon nanotube field emitters for electron microscopy

    NASA Astrophysics Data System (ADS)

    Nakahara, Hitoshi; Kusano, Yoshikazu; Kono, Takumi; Saito, Yahachi

    2009-11-01

    Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I- V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability of CNT for electron microscopy. As a result, it is obtained that an emission area of MWNT is smaller than its tip surface area, and the emission area corresponds to a five-membered-ring with 2nd nearest six-membered-rings on the MWNT cap surface. Reduced brightness of MWNT is measured as at least 2.6×109 A/m 2 sr V. It is concluded that even a thick MWNT has enough brightness under a practical e-gun electrode configuration and suitable for electron microscopy.

  8. Radiative Performance of Rare Earth Garnet Thin Film Selective Emitters

    NASA Technical Reports Server (NTRS)

    Lowe, Roland A.; Chubb, Donald L.; Good, Brian S.

    1994-01-01

    In this paper we present the first emitter efficiency results for the thin film 40 percent Er-1.5 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) and 25 percent Ho YAG selective emitter at 1500 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns). Emitter efficiency and power density are significantly improved with the addition of multiple rare earth dopants. Predicted efficiency results are presented for an optimized (equal power density in the Er, (4)I(sub 15/2)-(4)I(sub 13/2) at 1.5 microns, and Ho, (5)I(sub 7)-(5)I(sub 8) at 2.0 micron emission bands) Er-Ho YAG thin film selective emitter.

  9. GTF Transverse and Longitudinal Emittance Data Analysis Technique

    SciTech Connect

    Not Available

    2010-12-07

    The SSRL Gun Test Facility (GTF) was built to develop a high brightness electron injector for the LCLS and has been operational since 1996. Measurements at the GTF include quadrupole scan transverse emittance measurements and linac phase scan longitudinal emittance measurements. Typically the beam size is measured on a screen as a function of a quadrupole current or linac phase and the beam matrix is then fit to the measured data. Often the emittance which is the final result of the measurement is the only number reported. However, the method used to reduce the data to the final emittance value can have a significant effect on the result. This paper describes in painful detail the methods used to analyze the transverse and longitudinal emittance data collected at the GTF.

  10. Theory and measurements of emittance preservation in plasma wakefield acceleration

    SciTech Connect

    Frederico, Joel

    2016-12-01

    In this dissertation, we examine the preservation and measurement of emittance in the plasma wakefield acceleration blowout regime. Plasma wakefield acceleration (PWFA) is a revolutionary approach to accelerating charged particles that has been demonstrated to have the potential for gradients orders of magnitude greater than traditional approaches. The application of PWFA to the design of a linear collider will make new high energy physics research possible, but the design parameters must first be shown to be competitive with traditional methods. Emittance preservation is necessary in the design of a linear collider in order to maximize luminosity. We examine the conditions necessary for circular symmetry in the PWFA blowout regime, and demonstrate that current proposals meet these bounds. We also present an application of beam lamentation which describes the process of beam parameter and emittance matching. We show that the emittance growth saturates as a consequence of energy spread in the beam. The initial beam parameters determine the amount of emittance growth, while the contribution of energy spread is negligible. We also present a model for ion motion in the presence of a beam that is much more dense than the plasma. By combining the model of ion motion and emittance growth, we find the emittance growth due to ion motion is minimal in the case of marginal ion motion. In addition, we present a simulation that validates the ion motion model, which is under further development to examine emittance growth of both marginal and pronounced ion motion. Finally, we present a proof-of-concept of an emittance measurement which may enable the analysis of emittance preservation in future PWFA experiments.

  11. Electron beam emittance monitor for the SSC

    SciTech Connect

    Tsyganov, E.; Meinke, R.; Nexsen, W.; Kauffmann, S.; Zinchenko, A.; Taratin, A.

    1993-05-01

    A nondestructive beam profile monitor for the Superconducting Super Collider (SSC) is presented using as a probe a low-energy electron beam interacting with the proton bunch charge. Results using a full Monte Carlo simulation code look promising for the transverse and longitudinal beam profile measurements.

  12. RHIC Polarized proton operation

    SciTech Connect

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

    2011-03-28

    injection, the polarized hydrogen jet target runs for every fill with both beams. Based on the known analyzing power, there is very little polarization loss between injection and 100 GeV. An alternative way is to measure the asymmetry at 100 GeV followed by ramping up to 250 GeV and back down to 100 GeV and then to measure the asymmetry again at 100 GeV. If the asymmetry after the down ramp is similar to the measurement before the up ramp, polarization was also preserved during the ramp to 250 GeV. The analyzing power at storage energy can then be extracted from the asymmetries measured at 100 GeV and 250 GeV. The tune and orbit feedbacks are essential for the down ramp to be possible. The polarized proton operation is still going on. We will push bunch intensity higher until reaching the beam-beam limit. The even higher intensity will have to wait for the electron lenses to compensate the beam-beam effect. To understand the details of spin dynamics in RHIC with two snakes, spin simulation with the real magnet fields have been developed recently. The study will provide guidance for possible polarization loss schemes. Further polarization gain will requires a polarized source upgrade; more careful setup jump quads in the AGS to get full benefit; and control emittance in the whole accelerator chain.

  13. Powerful ultrawideband rf emitters: status and challenges

    NASA Astrophysics Data System (ADS)

    Agee, Forrest J.; Scholfield, David W.; Prather, William D.; Burger, Jeffrey W.

    1995-09-01

    Ultra-wideband emitters are of interest for a variety of potential applications that range from radar transmitters to communications applications. This technology is of current interest to the USAF Phillips Laboratory where theoretical and experimental efforts have been underway for a number of years. Research into the production of ultra-wideband sources at the Phillips Laboratory has been accomplished along several different technology lines. The approaches include three main thrusts: 1) very powerful hydrogen spark gap pulsers, 2) compact hydrogen gas switches in conjunction with high gain ultra-wideband antennas and, 3) solid state switched array antennas. This paper reviews the progress-to-date along these lines and identifies some pacing research obastacles that limit further improvements.

  14. Plasma treatment for producing electron emitters

    DOEpatents

    Coates, Don Mayo; Walter, Kevin Carl

    2001-01-01

    Plasma treatment for producing carbonaceous field emission electron emitters is disclosed. A plasma of ions is generated in a closed chamber and used to surround the exposed surface of a carbonaceous material. A voltage is applied to an electrode that is in contact with the carbonaceous material. This voltage has a negative potential relative to a second electrode in the chamber and serves to accelerate the ions toward the carbonaceous material and provide an ion energy sufficient to etch the exposed surface of the carbonaceous material but not sufficient to result in the implantation of the ions within the carbonaceous material. Preferably, the ions used are those of an inert gas or an inert gas with a small amount of added nitrogen.

  15. Gamma emitters in Hong Kong water

    SciTech Connect

    Shun-Yin, L.; Chung-Keung, M.; Wai-Kwok, N.; Shiu-Chun, A. )

    1990-01-01

    Radioactivity in water originates from natural and artificial sources. The development of a nuclear powerplant near Hong Kong necessitates that attention be given to formulating techniques to assess the possible resultant environmental radioactive contamination. Water samples collected from various sites in Hong Kong in the spring and summer of 1987, representing seawater, river water, reservoir water, drinking water, and underground water were studied through gamma-ray spectral analysis. Only gamma emitters in the U238 and Th232 series and K40 were detected. No fission product was detected with specific activity above 0.1 Bq/kg. The data could be the baseline for future monitoring of the radioactivity released from a nuclear plant being built at a 50-km distance from Hong Kong. The variation of detected specific activities may be due to geological differences and the effect of plants. 1 ref., 3 tabs.

  16. Lyman Alpha Emitters and Galaxy Formation Scenarios

    NASA Astrophysics Data System (ADS)

    Malhotra, S.; Kovac, K.; Somerville, R.; Moustakas, L.; Rhoads, J. E.

    2002-12-01

    The Large Area Lyman Alpha (LALA) survey has successfully identified the population of young Lyman-alpha emitting galaxies predicted about 35 years ago. High equivalent widths of the Lyman-alpha line in these sources suggest that they are a very young (age < 107 years), metal poor, population of stars at redshifts 4.5 and 5.7, making them very interesting objects to study in the context of galaxy formation scenarios. We have begun to do exactly this using the correlation function of LALA galaxies. While the strong correlation function indicates massive halos, the volume density of Lyman-alpha sources and the faint continuum levels indicate low-mass stellar systems. This discrepancy can be resolved by postulating multiple emitters in a single halo.

  17. Magnetic field emission gun with zirconiated emitter.

    PubMed

    Troyon, M

    1989-03-01

    A magnetic-field-superimposed field emission gun with low aberrations and equipped with a zirconiated tungsten emitter has been developed for applications where very stable high probe currents are required. It has been tested on a conventional electron microscope at 10 kV and on an electron beam testing system at 1 kV. Probe current i = 250 nA in a probe size d = 0.4 micron is obtained at 10 kV; at 1 kV the resolution is 0.1 micron with i = 5 nA, and 0.4 micron with i = 30 nA. For these probe currents, the spatial broadening effect due to electron-electron interactions in the beam is the preponderant factor limiting the probe size.

  18. Proton radiography to improve proton therapy treatment

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  19. Detectability of a Direct Sequence Emitter within a Network of Direct Sequence Emitters,

    DTIC Science & Technology

    1988-01-01

    interception over 1/R propagation paths requires very large, ground-based antennas in order to achieve a usable intercept Signal-to- Noise Ratio (SNR). On...the other hand, free space, 1/R 2 propagation paths provide intercept receivers with signal power levels well above tne thermal noise power even when...large enough to resolve individual emitters are too large to put on aircraft as required to achieve the necessary free space propagation. Hence, the

  20. Determination and error analysis of emittance and spectral emittance measurements by remote sensing. [of leaves, soil and plant canopies

    NASA Technical Reports Server (NTRS)

    Kumar, R.

    1977-01-01

    Theoretical and experimental determinations of the emittance of soils and leaves are reviewed, and an error analysis of emittance and spectral emittance measurements is developed as an aid to remote sensing applications. In particular, an equation for the upper bound of the absolute error in an emittance determination is derived. The absolute error is found to decrease with an increase in contact temperature and to increase with an increase in environmental integrated radiant flux density. The difference between temperature and band radiance temperature is plotted as a function of emittance for the wavelength intervals 4.5 to 5.5 microns, 8 to 13.5 microns and 10.2 to 12.5 microns.

  1. Physical electrostatics of small field emitter arrays/clusters

    NASA Astrophysics Data System (ADS)

    Forbes, Richard G.

    2016-08-01

    This paper aims to improve qualitative understanding of electrostatic influences on apex field enhancement factors (AFEFs) for small field emitter arrays/clusters. Using the "floating sphere at emitter-plate potential" (FSEPP) model, it re-examines the electrostatics and mathematics of three simple systems of identical post-like emitters. For the isolated emitter, various approaches are noted. An adequate approximation is to consider only the effects of sphere charges and (for significantly separated emitters) image charges. For the 2-emitter system, formulas are found for charge-transfer ("charge-blunting") effects and neighbor-field effects, for widely spaced and for "sufficiently closely spaced" emitters. Mutual charge-blunting is always the dominant effect, with a related (negative) fractional AFEF-change δtwo. For sufficiently small emitter spacing c, |δtwo| varies approximately as 1/c; for large spacing, |δtwo| decreases as 1/c3. In a 3-emitter equispaced linear array, differential charge-blunting and differential neighbor-field effects occur, but differential charge-blunting effects are dominant, and cause the "exposed" outer emitters to have higher AFEF (γ0) than the central emitter (γ1). Formulas are found for the exposure ratio Ξ = γ0/γ1, for large and for sufficiently small separations. The FSEPP model for an isolated emitter has accuracy around 30%. Line-charge models (LCMs) are an alternative, but an apparent difficulty with recent LCM implementations is identified. Better descriptions of array electrostatics may involve developing good fitting equations for AFEFs derived from accurate numerical solution of Laplace's equation, perhaps with equation form(s) guided qualitatively by FSEPP-model results. In existing fitting formulas, the AFEF-reduction decreases exponentially as c increases, which is different from the FSEPP-model formulas. This discrepancy needs to be investigated, using systematic Laplace-based simulations and appropriate results

  2. Proton decay theory

    SciTech Connect

    Marciano, W.J.

    1983-01-01

    Topics include minimal SU(5) predictions, gauge boson mediated proton decay, uncertainties in tau/sub p/, Higgs scalar effects, proton decay via Higgs scalars, supersymmetric SU(5), dimension 5 operators and proton decay, and Higgs scalars and proton decay. (WHK)

  3. Synchrotron based proton drivers

    SciTech Connect

    Weiren Chou

    2002-09-19

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

  4. A MEMS-based infrared emitter array for combat identification

    NASA Astrophysics Data System (ADS)

    San, Haisheng; Chen, Xuyuan; Xu, Peng; Li, Fangqiang; Cheng, Meiying

    2008-04-01

    The silicon-based MEMS (MEMS: microelectromechanical systems) Infrared (IR) emitter arrays of 1x2, 2x2 and 3x3 elements are presented. The MEMS infrared emitters were fabricated on silicon-on-insulator (SOI) wafer. The resistively heated poly-silicon membrane fabricated by using deep reactive ion etching (DRIE) process on backside of SOI wafer make a low thermal mass structure, thus this IR-emitter can be modulated at high frequency. A heavily boron doping technology enable the supporting silicon layer to absorb the infrared radiation. As a result, the self-heating effect will reduce the power loss. By using the SOI wafer, the fabrication processes are simplified, and the production costs are decreased. In experiment, the surface temperature distribution of IR emitter arrays were measured by thermal imaging system, and the optical spectrum and modulation characteristics were measured by spectroradiometer. The measured results show that the IR emitter arrays exhibit a strong emission in middle infrared range, and the modulation frequency at 0.5 modulation depth is about 30Hz. The emitter arrays are expected to improve performance by using suspended membrane and sealed package structure. It is expected that the IR emitter arrays can be used for increasing the visible intensity and distance in the application of infrared Combat Identification.

  5. Proton emission half-lives within a Gamow-like model

    NASA Astrophysics Data System (ADS)

    Zdeb, A.; Warda, M.; Petrache, C. M.; Pomorski, K.

    2016-10-01

    Proton emission is described using a model which has previously given good results in the description of α and cluster radioactivity. The simple phenomenological formalism, based on the Gamow theory for alpha decay, is now extended by including the centrifugal term. The model contains only one parameter: the effective nuclear radius constant. Its value was once found for alpha and cluster emitters. A good agreement with the experimental half-lives for proton radioactivity is achieved without any additional fitting procedures to the data for proton emission.

  6. Proton Therapy - Accelerating Protons to Save Lives

    SciTech Connect

    Keppel, Cynthia

    2011-10-25

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

  7. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

    SciTech Connect

    Wootton, Kent

    2015-09-17

    In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 #6;± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

  8. Thermal limit to the intrinsic emittance from metal photocathodes

    SciTech Connect

    Feng, Jun Nasiatka, J.; Wan, Weishi; Karkare, Siddharth; Padmore, Howard A.; Smedley, John

    2015-09-28

    Measurements of the intrinsic emittance and transverse momentum distributions obtained from a metal (antimony thin film) photocathode near and below the photoemission threshold are presented. Measurements show that the intrinsic emittance is limited by the lattice temperature of the cathode as the incident photon energy approaches the photoemission threshold. A theoretical model to calculate the transverse momentum distributions near this photoemission threshold is presented. An excellent match between the experimental measurements and the theoretical calculations is demonstrated. These measurements are relevant to low emittance electron sources for Free Electron Lasers and Ultrafast Electron Diffraction experiments.

  9. New Low Emittance Lattice for the Super-B Accelerator

    SciTech Connect

    Biagini, M.E.; Boscolo, M.; Raimondi, P.; Tomassini, S.; Zobov, M.; Seeman, J.; Sullivan, M.; Wienands, U.; Wittmer, W.; Bettoni, S.; Paoloni, E.; Bogomyagkov, A.; Koop, I.; Levichev, E.; Nikitin, S.; Piminov, P.; Shatilov, D.; /Novosibirsk, IYF

    2011-10-21

    New low emittance lattices have been designed for the asymmetric SuperB accelerator, aiming at a luminosity of 10{sup 36} cm{sup -2} s{sup -1}. Main optics features are two alternating arc cells with different horizontal phase advance, decreasing beam emittance and allowing at the same time for easy chromaticity correction in the arcs. Emittance can be further reduced by a factor of two for luminosity upgrade. Spin rotation schemes for the e{sup -} beam have been studied to provide longitudinal polarization at the IP, and implementation into the lattice is in progress.

  10. Longitudinal emittance growth due to nonlinear space charge effect

    NASA Astrophysics Data System (ADS)

    Lau, Y. Y.; Yu, Simon S.; Barnard, John J.; Seidl, Peter A.

    2012-03-01

    Emittance posts limits on the key requirements of final pulse length and spot size on target in heavy ion fusion drivers. In this paper, we show studies on the effect of nonlinear space charge on longitudinal emittance growth in the drift compression section. We perform simulations, using the 3D PIC code WARP, for a high current beam under conditions of bends and longitudinal compression. The linear growth rate for longitudinal emittance turns out to depend only on the peak line charge density, and is independent of pulse length, velocity tilt, and/or the pipe and beam size. This surprisingly simple result is confirmed by simulations and analytic calculations.

  11. The dust nature of micro field emitters in accelerators

    NASA Astrophysics Data System (ADS)

    Volkov, V.; Petrov, V. M.

    2016-11-01

    Field emission currents emitted by micro-emitters are a limiting factor for the operational gradients of accelerating radio frequency (rf) cavities. Within the rf field emission theory the existence of needle like micro field emitters with very high length relative to the radius and corresponding high enhancement factor (β) is assumed. In this article the hypothesis that micro field emitters consists of long chains of conductive micro-particles is considered. Five different forces acting onto the particles in a high rf field are considered and the respective equations are derived. Some experimental observations and their explanation within this hypothesis are discussed.

  12. Method and apparatus for multispray emitter for mass spectrometry

    DOEpatents

    Smith, Richard D.; Tang, Keqi; Lin, Yuehe

    2004-12-14

    A method and apparatus that utilizes two or more emitters simultaneously to form an electrospray of a sample that is then directed into a mass spectrometer, thereby increasing the total ion current introduced into an electrospray ionization mass spectrometer, given a liquid flow rate of a sample. The method and apparatus are most conveniently constructed as an array of spray emitters fabricated on a single chip, however, the present invention encompasses any apparatus wherein two or more emitters are simultaneously utilized to form an electrospray of a sample that is then directed into a mass spectrometer.

  13. Observation of picometer vertical emittance with a vertical undulator.

    PubMed

    Wootton, K P; Boland, M J; Dowd, R; Tan, Y-R E; Cowie, B C C; Papaphilippou, Y; Taylor, G N; Rassool, R P

    2012-11-09

    Using a vertical undulator, picometer vertical electron beam emittances have been observed at the Australian Synchrotron storage ring. An APPLE-II type undulator was phased to produce a horizontal magnetic field, which creates a synchrotron radiation field that is very sensitive to the vertical electron beam emittance. The measured ratios of undulator spectral peak heights are evaluated by fitting to simulations of the apparatus. With this apparatus immediately available at most existing electron and positron storage rings, we find this to be an appropriate and novel vertical emittance diagnostic.

  14. Emittance Compensation in a Flat Beam RF Photoinjector

    NASA Astrophysics Data System (ADS)

    Rosenzweig, J. B.; Anderson, S.; Colby, E.; Serafini, L.

    1997-05-01

    The beam dynamics of a flat beam rf photoinjector, which is intended to produce asymmetric emittances for linear collider applications, are analyzed, by both analytical and computational methods. The analytical model is a generalization of the recently developed theory of emittance compensation in round beams(L.Serafini, and J.B. Rosenzweig, submitted to Physical Review E.), in which a new mode of laminar flow beam dynamics, the invariant envelope, is found to give the ideal conditions for emittance minimization. Three-dimensional rf and beam dynamics simulations are used to iluminate the analytical results. abstract.

  15. A resonance-free nano-film airborne ultrasound emitter

    NASA Astrophysics Data System (ADS)

    Daschewski, Maxim; Harrer, Andrea; Prager, Jens; Kreutzbruck, Marc; Beck, Uwe; Lange, Thorid; Weise, Matthias

    2013-01-01

    In this contribution we present a novel thermo-acoustic approach for the generation of broad band airborne ultrasound and investigate the applicability of resonance-free thermo-acoustic emitters for very short high pressure airborne ultrasound pulses. We report on measurements of thermo-acoustic emitter consisting of a 30 nm thin metallic film on a usual soda-lime glass substrate, generating sound pressure values of more than 140 dB at 60 mm distance from the transducer and compare the results with conventional piezoelectric airborne ultrasound transducers. Our experimental investigations show that such thermo-acoustic devices can be used as broad band emitters using pulse excitation.

  16. Design of a minimum emittance nBA lattice

    NASA Astrophysics Data System (ADS)

    Lee, S. Y.

    1998-04-01

    An attempt to design a minimum emittance n-bend achromat (nBA) lattice has been made. One distinct feature is that dipoles with two different lengths were used. As a multiple bend achromat, five bend achromat lattices with six superperiod were designed. The obtained emittace is three times larger than the theoretical minimum. Tunes were chosen to avoid third order resonances. In order to correct first and second order chromaticities, eight family sextupoles were placed. The obtained emittance of five bend achromat lattices is almost equal to the minimum emittance of five bend achromat lattice consisting of dipoles with equal length.

  17. Optimization and beam control in large-emittance accelerators: Neutrino factories;

    SciTech Connect

    Carol Johnstone

    2004-08-23

    Schemes for intense sources of high-energy muons require collection, rf capture, and transport of particle beams with unprecedented emittances, both longitudinally and transversely. These large emittances must be reduced or ''cooled'' both in size and in energy spread before the muons can be efficiently accelerated. Therefore, formation of muon beams sufficiently intense to drive a Neutrino Factory or Muon Collider requires multi-stage preparation. Further, because of the large beam phase space which must be successfully controlled, accelerated, and transported, the major stages that comprise such a facility: proton driver, production, capture, phase rotation, cooling, acceleration, and storage are complex and strongly interlinked. Each of the stages must be consecutively matched and simultaneously optimized with upstream and downstream systems, meeting challenges not only technically in the optics and component design, but also in the modeling of both new and extended components. One design for transverse cooling, for example, employs meter-diameter solenoids to maintain strong focusing--300-500 mr beam divergences--across ultra-large momentum ranges, {ge} {+-}20% {delta}p/p, defying conventional approximations to the dynamics and field representation. To now, the interplay of the different systems and staging strategies has not been formally addressed. This work discusses two basic, but different approaches to a Neutrino Factory and how the staging strategy depends on beam parameters and method of acceleration.

  18. {sup 119}Sb--A potent Auger emitter for targeted radionuclide therapy

    SciTech Connect

    Thisgaard, H.; Jensen, M.

    2008-09-15

    Auger electron emitting radionuclides in cancer therapy offer the opportunity to deliver a high radiation dose to the tumor cells with high radiotoxicity while minimizing toxicity to normal tissue. We have in this study identified the Auger emitter {sup 119}Sb as a potent nuclide for targeted radionuclide therapy based on theoretical dosimetry calculations at a subcellular scale. From these calculations we have determined the cellular S-values for this therapeutic isotope. Moreover, we have demonstrated the possibility of producing this isotope and also the SPECT-analogue {sup 117}Sb for patient-specific dosimetry, by measuring the proton irradiation yields for both isotopes using a low-energy cyclotron. The excellent SPECT imaging properties of the {sup 117}Sb radionuclide have been shown by scanning a Jaszczak SPECT Phantom.

  19. Plasmonic enhancement engineering of semiconductor light emitters

    NASA Astrophysics Data System (ADS)

    Henson, John Timothy Irvine

    Light emitting diodes (LEDs) are light sources of great technological importance because of their wide spectral tunability, long lifetimes, and potentially high energy efficiency. It is widely observed, however, that LEDs based on all relevant material platforms exhibit degraded internal quantum efficiency as the emission wavelength is shifted into the green part of the visible spectrum. Increasing device efficiency in this spectral region has therefore become the focus of intense research. In this work we study the use of plasmonic metallic nanostructures as a method for enhancing LED efficiency. Electromagnetic fields are known to exhibit resonances near metallic nanostructures originating from collective oscillations of the electron gas on the metal surface. Surface plasmon polaritons (SPPs) confined to the surface of a planar metal film, and localized surface plasmons (LSPs) confined to the surface of a nanostructure, feature unique optical properties such as large near optical fields and large modal densities. These spatial and spectral properties are highly dependent on the material and geometric properties of the nanostructure, allowing for extensive engineering of the plasmonic system to meet application needs. Plasmonic nanostructures are currently being studied for use in a wide range of applications such as waveguiding, bio-sensing, surface-enhanced spectroscopy, solid state light emission, and solar cells. Coupling into both SPP and LSP modes can enhance the spontaneous emission rate of a nearby radiating dipole, by virtue of their large associated local optical fields and high density of modes. Effective scattering of the excited plasmonic resonances into the radiation continuum can then lead to large enhancements in radiated field intensity. In this work, we have studied the application of various metallic nanostructures to nitride semiconductor light emitters to enhance their emission efficiency. Numerical investigations have been conducted to

  20. Engineered Emitters for Improved Silicon Photovoltaics

    NASA Astrophysics Data System (ADS)

    Kamat, Ronak A.

    In 2014, installation of 5.3GW of new Photovoltaic (PV) systems occurred in the United States, raising the total installed capacity to 16.36GW. Strong growth is predicted for the domestic PV market with analysts reporting goals of 696GW by 2020. Conventional single crystalline silicon cells are the technology of choice, accounting for 90% of the installations in the global commercial market. Cells made of GaAs offer higher efficiencies, but at a substantially higher cost. Thin film technologies such as CIGS and CdTe compete favorably with multi-crystalline Si (u-Si), but at 20% efficiency, still lag the c-Si cell in performance. The c-Si cell can be fabricated to operate at approximately 25% efficiency, but commercially the efficiencies are in the 18-21% range, which is a direct result of cost trade-offs between process complexity and rapid throughput. With the current cost of c-Si cell modules at nearly 0.60/W. The technology is well below the historic metric of 1/W for economic viability. The result is that more complex processes, once cost-prohibitive, may now be viable. An example is Panasonic's HIT cell which operates in the 22-24% efficiency range. To facilitate research and development of novel PV materials and techniques, RIT has developed a basic solar cell fabrication process. Student projects prior to this work had produced cells with 12.8% efficiency using p type substrates. This thesis reports on recent work to improve cell efficiencies while simultaneously expanding the capability of the rapid prototyping process. In addition to the p-Si substrates, cells have been produced using n-Si substrates. The cell emitter, which is often done with a single diffusion or implant has been re-engineered using a dual implant of the same dose. This dual-implanted emitter has been shown to lower contact resistance, increase Voc, and increase the efficiency. A p-Si substrate cell has been fabricated with an efficiency of 14.6% and n-Si substrate cell with a 13

  1. Red surface emitters: powerful and fast

    NASA Astrophysics Data System (ADS)

    Schweizer, Heinz; Ballmann, Tabitha; Butendeich, Rainer; Rossbach, Robert; Raabe, Bernd; Jetter, Michael; Scholz, Ferdinand

    2003-12-01

    Vertical cavity surface emitting lasers (VCSEL) in the GaInP/AlGaInP material system have experienced a rapid development in their short history. In general lasers from that material system are suitable for a huge number of applications beginning with TV lasers and high power lasers for edge emitters, continuing with optical data storage, medical applications as well as data communication in cars, air planes, offices and between computers as application field for VCSELs. Especially automotive applications show the highest requirements on a laser with respect to operation temperature and power. In this talk we draw out the problems of the material system AlGaInP and its implications for laser applications. We discuss the epitaxial and technological solutions to overcome at least a part of these inherent problems. We will discuss the possible power that we can expect from VCSELs emitting in the range between 650 nm to 670 nm. We got from our lasers 5 mW, CW @ RT, 670nm and 2.5mW, CW@RT, 650 nm. We emphasize the role of doping, Bragg mirror grading, suitable detuning of cavity mode and gain, and optimisation of the contact layer and control of the oxide aperture in the VCSEL structure to get improved operation characteristics at higher temperatures. From the analysis of high frequency measurements, we could evaluate modulation bandwidths between 4 GHz and 10 GHz. The application of polyimide as a dielectric isolation material shows the potential to obtain modulation bandwidths beyond 10 GHz. For the intrinsic modulation bandwidth we get a value of 25 GHz, which is near the value edge emitters show. A more detailed discussion on photon lifetimes and carrier transport times will be given in the talk. Red light emitting VCSELS driven with short current pulses showed laser emission up to + 160°C case temperature. Thus, a CW operation up to +120°C can be expected after further improvement of power generation (decrease of series resistance) and heat spreading (optimized

  2. Improved Rare-Earth Emitter Hollow Cathode

    NASA Technical Reports Server (NTRS)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  3. RADIOACTIVE POSITRON EMITTER PRODUCTION BY ENERGETIC ALPHA PARTICLES IN SOLAR FLARES

    SciTech Connect

    Murphy, R. J.; Kozlovsky, B.; Share, G. H. E-mail: benz@wise.tau.ac.il

    2015-01-01

    Measurements of the 0.511 MeV positron-annihilation line from solar flares are used to explore the flare process in general and ion acceleration in particular. In flares, positrons are produced primarily by the decay of radioactive positron-emitting isotopes resulting from nuclear interactions of flare-accelerated ions with ambient solar material. Kozlovsky et al. provided ion-energy-dependent production cross sections for 67 positron emitters evaluated from their threshold energies (some <1 MeV nucleon{sup –1}) to a GeV nucleon{sup –1}, incorporating them into a computer code for calculating positron-emitter production. Adequate cross-section measurements were available for proton reactions, but not for α-particle reactions where only crude estimates were possible. Here we re-evaluate the α-particle cross sections using new measurements and nuclear reaction codes. In typical large gamma-ray line flares, proton reactions dominate positron production, but α-particle reactions will dominate for steeper accelerated-ion spectra because of their relatively low threshold energies. With the accelerated-{sup 3}He reactions added previously, the code is now reliable for calculating positron production from any distribution of accelerated-ion energies, not just those of typical flares. We have made the code available in the online version of the Journal. We investigate which reactions, projectiles, and ion energies contribute to positron production. We calculate ratios of the annihilation-line fluence to fluences of other gamma-ray lines. Such ratios can be used in interpreting flare data and in determining which nuclear radiation is most sensitive for revealing acceleration of low-energy ions at the Sun.

  4. Dose-volume delivery guided proton therapy using beam on-line PET system

    SciTech Connect

    Nishio, Teiji; Ogino, Takashi; Nomura, Kazuhiro; Uchida, Hiroshi

    2006-11-15

    Proton therapy is one form of radiotherapy in which the irradiation can be concentrated on a tumor using a scanned or modulated Bragg peak. Therefore, it is very important to evaluate the proton-irradiated volume accurately. The proton-irradiated volume can be confirmed by detection of pair annihilation gamma rays from positron emitter nuclei generated by the target nuclear fragment reaction of irradiated proton nuclei and nuclei in the irradiation target using a positron emission tomography (PET) apparatus, and dose-volume delivery guided proton therapy (DGPT) can thereby be achieved using PET images. In the proton treatment room, a beam ON-LINE PET system (BOLPs) was constructed so that a PET apparatus of the planar-type with a high spatial resolution of about 2 mm was mounted with the field of view covering the isocenter of the beam irradiation system. The position and intensity of activity were measured using the BOLPs immediately after the proton irradiation of a gelatinous water target containing {sup 16}O nuclei at different proton irradiation energy levels. The change of the activity-distribution range against the change of the physical range was observed within 2 mm. The experiments of proton irradiation to a rabbit and the imaging of the activity were performed. In addition, the proton beam energy used to irradiate the rabbit was changed. When the beam condition was changed, the difference between the two images acquired from the measurement of the BOLPs was confirmed to clearly identify the proton-irradiated volume.

  5. Particle Simulations of a Linear Dielectric Wall Proton Accelerator

    SciTech Connect

    Poole, B R; Blackfield, D T; Nelson, S D

    2007-06-12

    The dielectric wall accelerator (DWA) is a compact induction accelerator structure that incorporates the accelerating mechanism, pulse forming structure, and switch structure into an integrated module. The DWA consists of stacked stripline Blumlein assemblies, which can provide accelerating gradients in excess of 100 MeV/meter. Blumleins are switched sequentially according to a prescribed acceleration schedule to maintain synchronism with the proton bunch as it accelerates. A finite difference time domain code (FDTD) is used to determine the applied acceleration field to the proton bunch. Particle simulations are used to model the injector as well as the accelerator stack to determine the proton bunch energy distribution, both longitudinal and transverse dynamic focusing, and emittance growth associated with various DWA configurations.

  6. RHIC 100 GeV Polarized Proton Luminosity

    SciTech Connect

    Zhang, S. Y.

    2014-01-17

    A big problem in RHIC 100 GeV proton run 2009 was the significantly lower luminosity lifetime than all previous runs. It is shown in this note that the beam intensity decay in run 2009 is caused by the RF voltage ramping in store. It is also shown that the beam decay is not clearly related to the beam momentum spread, therefore, not directly due to the 0.7m. β* Furthermore, the most important factor regarding the low luminosity lifetime is the faster transverse emittance growth in store, which is also much worse than the previous runs, and is also related to the RF ramping. In 100 GeV proton run 2012a, the RF ramping was abandoned, but the β* was increased to 0.85m, with more than 20% loss of luminosity, which is not necessary. It is strongly suggested to use smaller β* in 100 GeV polarized proton run 2015/2016

  7. Absolute beam emittance measurements at RHIC using ionization profile monitors

    SciTech Connect

    Minty, M.; Connolly, R; Liu, C.; Summers, T.; Tepikian, S.

    2014-08-15

    In the past, comparisons between emittance measurements obtained using ionization profile monitors, Vernier scans (using as input the measured rates from the zero degree counters, or ZDCs), the polarimeters and the Schottky detectors evidenced significant variations of up to 100%. In this report we present studies of the RHIC ionization profile monitors (IPMs). After identifying and correcting for two systematic instrumental errors in the beam size measurements, we present experimental results showing that the remaining dominant error in beam emittance measurements at RHIC using the IPMs was imprecise knowledge of the local beta functions. After removal of the systematic errors and implementation of measured beta functions, precise emittance measurements result. Also, consistency between the emittances measured by the IPMs and those derived from the ZDCs was demonstrated.

  8. Single-knob beam line for transverse emittance partitioning

    NASA Astrophysics Data System (ADS)

    Xiao, C.; Kester, O. K.; Groening, L.; Leibrock, H.; Maier, M.; Rottländer, P.

    2013-04-01

    Flat beams feature unequal emittances in the horizontal and vertical phase space. Such beams were created successfully in electron machines by applying effective stand-alone solenoid fringe fields in the electron gun. Extension of this method to ion beams was proposed conceptually. The present paper is on the decoupling capabilities of an ion beam emittance transfer line. The proposed beam line provides a single-knob tool to partition the horizontal and vertical rms emittances, while keeping the product of the two emittances constant as well as the transverse rms Twiss parameters (αx,y and βx,y) in both planes. It is shown that this single knob is the solenoid field strength.

  9. Non-blinking single-photon emitters in silica

    NASA Astrophysics Data System (ADS)

    Rabouw, Freddy T.; Cogan, Nicole M. B.; Berends, Anne C.; Stam, Ward Van Der; Vanmaekelbergh, Daniel; Koenderink, A. Femius; Krauss, Todd D.; Donega, Celso De Mello

    2016-02-01

    Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect colour centres that fluoresce when excited at 532 nm. In a microscope image the defect emission is indistinguishable from spin-coated emitters. The emission spectrum is characterised by multiple peaks with the main peak between 2.05 and 2.20 eV, most likely due to coupling to a silica vibration with an energy that varies between 160 and 180 meV. The defects are single-photon emitters, do not blink, and have photoluminescence lifetimes of a few nanoseconds. Photoluminescence from such defects may previously have been misinterpreted as originating from single nanocrystal quantum dots.

  10. Non-blinking single-photon emitters in silica

    DOE PAGES

    Rabouw, Freddy T.; Cogan, Nicole M. B.; Berends, Anne C.; ...

    2016-02-19

    Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect colour centres that fluoresce when excited at 532 nm. In a microscope image the defect emission is indistinguishable from spin-coated emitters. The emission spectrum is characterised by multiple peaks with the main peak between 2.05 and 2.20 eV, most likely due to coupling to a silica vibration with an energy that varies between 160 and 180 meV. The defects are single-photon emitters,more » do not blink, and have photoluminescence lifetimes of a few nanoseconds. Furthermore, photoluminescence from such defects may previously have been misinterpreted as originating from single nanocrystal quantum dots.« less

  11. Non-blinking single-photon emitters in silica

    SciTech Connect

    Rabouw, Freddy T.; Cogan, Nicole M. B.; Berends, Anne C.; Stam, Ward van der; Vanmaekelbergh, Daniel; Koenderink, A. Femius; Krauss, Todd D.; Donega, Celso de Mello

    2016-02-19

    Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect colour centres that fluoresce when excited at 532 nm. In a microscope image the defect emission is indistinguishable from spin-coated emitters. The emission spectrum is characterised by multiple peaks with the main peak between 2.05 and 2.20 eV, most likely due to coupling to a silica vibration with an energy that varies between 160 and 180 meV. The defects are single-photon emitters, do not blink, and have photoluminescence lifetimes of a few nanoseconds. Furthermore, photoluminescence from such defects may previously have been misinterpreted as originating from single nanocrystal quantum dots.

  12. Rare Earth Doped High Temperature Ceramic Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

  13. Single-photon emitters in GaSe

    NASA Astrophysics Data System (ADS)

    Tonndorf, Philipp; Schwarz, Stefan; Kern, Johannes; Niehues, Iris; Del Pozo-Zamudio, Osvaldo; Dmitriev, Alexander I.; Bakhtinov, Anatoly P.; Borisenko, Dmitry N.; Kolesnikov, Nikolai N.; Tartakovskii, Alexander I.; Michaelis de Vasconcellos, Steffen; Bratschitsch, Rudolf

    2017-06-01

    Single-photon sources are important building blocks for quantum information technology. Emitters based on solid-state systems provide a viable route to integration in photonic devices. Here, we report on single-photon emitters in the layered semiconductor GaSe. We identify the exciton and biexciton transition of the quantum emitters with power-dependent photoluminescence and photon statistics measurements. We find evidence that the localization of the excitons is related to deformations of the GaSe crystal, caused by nanoscale selenium inclusions, which are incorporated in the crystal. These deformations give rise to local strain fields, which induce confinement potentials for the excitons. This mechanism lights the way for the controlled positioning of single-photon emitters in GaSe on the nanoscale.

  14. Emittance of TD-NiCr after simulated reentry

    NASA Technical Reports Server (NTRS)

    Clark, R. K.; Dicus, D. L.; Lisagor, W. B.

    1978-01-01

    The effects of simulated reentry heating on the emittance of TD-NiCr were investigated. Groups of specimens with three different preconditioning treatments were exposed to 6, 24, and 30 half-hour simulated reentry exposure cycles in a supersonic arc tunnel at each of three conditions intended to produce surface temperatures of 1255, 1365, and 1475 K. Emittance was determined at 1300 K on specimens which were preconditioned only and specimens after completion of reentry simulation exposure. Oxide morphology and chemistry were studied by scanning electron microscopy and X-ray diffraction analysis. A consistent relationship was established between oxide morphology and total normal emittance. Specimens with coarser textured oxides tended to have lower emittances than specimens with finer textured oxides.

  15. Localization of Narrowband Single Photon Emitters in Nanodiamonds.

    PubMed

    Bray, Kerem; Sandstrom, Russell; Elbadawi, Christopher; Fischer, Martin; Schreck, Matthias; Shimoni, Olga; Lobo, Charlene; Toth, Milos; Aharonovich, Igor

    2016-03-23

    Diamond nanocrystals that host room temperature narrowband single photon emitters are highly sought after for applications in nanophotonics and bioimaging. However, current understanding of the origin of these emitters is extremely limited. In this work, we demonstrate that the narrowband emitters are point defects localized at extended morphological defects in individual nanodiamonds. In particular, we show that nanocrystals with defects such as twin boundaries and secondary nucleation sites exhibit narrowband emission that is absent from pristine individual nanocrystals grown under the same conditions. Critically, we prove that the narrowband emission lines vanish when extended defects are removed deterministically using highly localized electron beam induced etching. Our results enhance the current understanding of single photon emitters in diamond and are directly relevant to fabrication of novel quantum optics devices and sensors.

  16. Nanobubble induced formation of quantum emitters in monolayer semiconductors

    NASA Astrophysics Data System (ADS)

    Shepard, Gabriella D.; Ajayi, Obafunso A.; Li, Xiangzhi; Zhu, X.-Y.; Hone, James; Strauf, Stefan

    2017-06-01

    The recent discovery of exciton quantum emitters in transition metal dichalcogenides (TMDCs) has triggered renewed interest of localized excitons in low-dimensional systems. Open questions remain about the microscopic origin previously attributed to dopants and/or defects as well as strain potentials. Here we show that the quantum emitters can be deliberately induced by nanobubble formation in WSe2 and BN/WSe2 heterostructures. Correlations of atomic-force microscope and hyperspectral photoluminescence images reveal that the origin of quantum emitters and trion disorder is extrinsic and related to 10 nm tall nanobubbles and 70 nm tall wrinkles, respectively. We further demonstrate that ‘hot stamping’ results in the absence of 0D quantum emitters and trion disorder. The demonstrated technique is useful for advances in nanolasers and deterministic formation of cavity-QED systems in monolayer materials.

  17. Innovative energy efficient low-voltage electron beam emitters

    NASA Astrophysics Data System (ADS)

    Felis, Kenneth P.; Avnery, Tovi; Berejka, Anthony J.

    2002-03-01

    Advanced electron beams (AEB) has developed a modular, low voltage (80-125 keV), high beam current (up to 40 ma), electron emitter with typically 25 cm of beam width, that is housed in an evacuated, returnable chamber that is easy to plug in and connect. The latest in nanofabrication enables AEB to use an ultra-thin beam window. The power supply for AEB's emitter is based on solid-state electronics. This combination of features results in a remarkable electrical efficiency. AEB's electron emitter relies on a touch screen, computer control system. With 80 μm of unit density beam penetration, AEB's electron emitter has gained market acceptance in the curing of opaque, pigmented inks and coatings used on flexible substrates, metals and fiber composites and in the curing of adhesives in foil based laminates.

  18. CSR-induced emittance growth in achromats: Linear formalism revisited

    NASA Astrophysics Data System (ADS)

    Venturini, M.

    2015-09-01

    We review the R-matrix formalism used to describe Coherent Synchrotron Radiation (CSR)-induced projected emittance growth in electron beam transport lines and establish the connection with a description in terms of the dispersion-invariant function.

  19. FXR LIA Optimization - Time-resolved OTR Emittance Measurement

    SciTech Connect

    Jacob, J; Ong, M; Wargo, P; LeSage, G

    2005-07-21

    The Flash X-Ray Radiography (FXR) facility at Lawrence Livermore National Laboratory utilizes a high current, long pulse linear induction accelerator to produce high doses of x-ray radiation. Accurate characterization of the transverse beam emittance is required in order to facilitate accelerator modeling and tuning efforts and, ultimately, to optimize the final focus spot size, yielding higher resolution radiographs. In addition to conventional magnet scan, pepper-pot, and multiple screen techniques, optical transition radiation (OTR) has been proven as a useful emittance measurement diagnostic and is particularly well suited to the FXR accelerator. We shall discuss the time-resolved emittance characterization of an induction linac electron beam using OTR, and we will present our experimental apparatus and analysis software. We shall also develop the theoretical background of beam emittance and transition radiation.

  20. Plasmonic nanochannel structure for narrow-band selective thermal emitter

    NASA Astrophysics Data System (ADS)

    Wang, Zhiyu; Clark, J. Kenji; Huang, Li-Chung; Ho, Ya-Lun; Delaunay, Jean-Jacques

    2017-06-01

    A plasmonic structure consisting of a periodic arrangement of vertical silicon nanochannels connected by U-shaped gold layers is demonstrated as a spectrally selective thermal emitter. The plasmonic nanochannel structure sustains a coupled mode between a surface plasmon polariton and a stationary surface plasmon resonance, which induces a strong and sharp resonance observed in the form of a reflectance dip in the far field. Upon heating the structure, a strong and narrow-bandwidth thermal emittance peak is observed with a maximum emittance value of 0.72 and a full-width-at-half-maximum of 248 nm at a wavelength of 5.66 μm, which corresponds to the reflectance dip wavelength. Moreover, we demonstrate the control of the emission peak wavelength by varying the period of the structure. The plasmonic nanochannel structure realizes a small-size and selective infrared thermal emitter, which is expected to be applicable as an infrared light source.

  1. Progress on the emitter wrap-through silicon solar cell

    NASA Astrophysics Data System (ADS)

    Gee, J. M.; Buck, M. E.; Schubert, W. K.; Basore, P. A.

    The Emitter Wrap-Through (EWT) solar cell is a back-contacted solar cell with a carrier-collection junction (emitter) on the front surface. Elimination of grids from the front surface allows for higher performance by eliminating grid-obscuration losses and reducing series resistance, while keeping an emitter on the front surface maintains high collection efficiency in solar-grade materials with modest diffusion lengths. The EWT cell uses laser-drilled vias to wrap the emitter diffusion on the front surface to interdigitated contacts on the back surface. We report on progress towards demonstration of two concepts for the EWT cell. The first EWT concept uses a fabrication sequence based on heavily diffused grooves and plated metallizations, and the second EWT concept uses a single furnace step and screen-printed metallizations. We also report on demonstration of double-sided carrier collection in the EWT cell.

  2. The emittance of space radiator materials measured at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Mirtich, Michael J.; Difilippo, Frank; Barry, Jennifer; Kussmaul, Michael

    1988-01-01

    The spectral emittances of textured space radiator materials between 1.7 and 14.7 micrometer have been evaluated at room temperature and elevated temperature (630 C) in air. Heating in air caused a permanent increase in spectral emittance for all materials tested: HCl/ion beam textured 304 stainless steel, untextured Ti (6 percent Al, 4 percent V), and sandblasted Ti (6 percent Al, 4 percent V). Changes in the surface chemistry and/or surface morphology of these materials were also observed. Elevated temperature spectral emittance was measured in an argon atmosphere and compared to the measurements in air. Similarity between the room temperature and elevated temperature spectral emittance measurements was also investigated, and limited agreement was found.

  3. Recent Developments of Low-emittance Electron Gun for Accelerator

    NASA Astrophysics Data System (ADS)

    Kuriki, Masao

    Recent developments of low-emittance electron guns for accelerator are reviewed. In the accelerator field, DC biased triode thermionic gun (Pierce type gun) has been widely used and is still conventional. On the other hand, because of strong demands on the high brightness electron beam by FEL and other advanced accelerator concepts based on linear accelerator, the low emittance beam generation becomes one of the most important issue in the accelerator science. The R&D effort is “accelerated” by two technological innovations, photo-cathode and RF gun. They made a large improvement on the beam emittance. After the explanations on the technical and physical aspects of the low emittance electron beam generation, advanced electron sources for accelerators are reviewed.

  4. Halo Formation And Emittance Growth of Positron Beams in Plasmas

    SciTech Connect

    Muggli, P.; Blue, B.E.; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, C.; Joshi, C.; Katsouleas, Thomas C.; Lu, W.; Mori, W.B.; O'Connell, C.L.; Siemann, R.H.; Walz, D.; Zhou, M.; /UCLA

    2011-10-25

    An ultrarelativistic 28.5 GeV, 700-{micro}m-long positron bunch is focused near the entrance of a 1.4-m-long plasma with a density n{sub e} between {approx}10{sup 13} and {approx}5 x 10{sup 14} cm{sup -3}. Partial neutralization of the bunch space charge by the mobile plasma electrons results in a reduction in transverse size by a factor of {approx}3 in the high emittance plane of the beam {approx}1 m downstream from the plasma exit. As n{sub e} increases, the formation of a beam halo containing {approx}40% of the total charge is observed, indicating that the plasma focusing force is nonlinear. Numerical simulations confirm these observations. The bunch with an incoming transverse size ratio of {approx}3 and emittance ratio of {approx}5 suffers emittance growth and exits the plasma with approximately equal sizes and emittances.

  5. Non-blinking single-photon emitters in silica

    PubMed Central

    Rabouw, Freddy T.; Cogan, Nicole M. B.; Berends, Anne C.; Stam, Ward van der; Vanmaekelbergh, Daniel; Koenderink, A. Femius; Krauss, Todd D.; Donega, Celso de Mello

    2016-01-01

    Samples for single-emitter spectroscopy are usually prepared by spin-coating a dilute solution of emitters on a microscope cover slip of silicate based glass (such as quartz). Here, we show that both borosilicate glass and quartz contain intrinsic defect colour centres that fluoresce when excited at 532 nm. In a microscope image the defect emission is indistinguishable from spin-coated emitters. The emission spectrum is characterised by multiple peaks with the main peak between 2.05 and 2.20 eV, most likely due to coupling to a silica vibration with an energy that varies between 160 and 180 meV. The defects are single-photon emitters, do not blink, and have photoluminescence lifetimes of a few nanoseconds. Photoluminescence from such defects may previously have been misinterpreted as originating from single nanocrystal quantum dots. PMID:26892489

  6. Design rules for core/shell nanowire resonant emitters

    NASA Astrophysics Data System (ADS)

    Kim, Da-Som; Kim, Sun-Kyung

    2017-01-01

    We study design principles to boost the extraction of light from core/shell GaN nanowire optical emitters. A full-vectorial electromagnetic simulation reveals that the extraction efficiency of an emitter within a nanowire cavity depends strongly on its position; the efficiency becomes maximized as the emitter's location approaches the center of the structure. The total extraction of light is sinusoidally modulated by the nanowire diameter, which is directly correlated with optical resonances. The introduction of a conformal dielectric coating on a nanowire leads to a dramatic enhancement in the extraction efficiency, which results from an increase in side emission owing to an optical antenna effect. A simple high-refractive-index dielectric coating approximately doubles the total extraction efficiency of a nanowire LED. These numerical findings will be valuable in providing strategies for high-efficiency nanowire-based optical emitters.

  7. Two-photon interference from two blinking quantum emitters

    NASA Astrophysics Data System (ADS)

    Jöns, Klaus D.; Stensson, Katarina; Reindl, Marcus; Swillo, Marcin; Huo, Yongheng; Zwiller, Val; Rastelli, Armando; Trotta, Rinaldo; Björk, Gunnar

    2017-08-01

    We investigate the effect of blinking on the two-photon interference measurement from two independent quantum emitters. We find that blinking significantly alters the statistics in the Hong-Ou-Mandel second-order intensity correlation function g(2 )(τ ) and the outcome of two-photon interference measurements performed with independent quantum emitters. We theoretically demonstrate that the presence of blinking can be experimentally recognized by a deviation from the gD(2 )(0 ) =0.5 value when distinguishable photons from two emitters impinge on a beam splitter. Our findings explain the significant differences between linear losses and blinking for correlation measurements between independent sources and are experimentally verified using a parametric down-conversion photon-pair source. We show that blinking imposes a mandatory cross-check measurement to correctly estimate the degree of indistinguishability of photons emitted by independent quantum emitters.

  8. Measurement of Emittance of Beam in the Debuncher During Stacking

    SciTech Connect

    Halling, Mike

    1991-12-11

    The emittance of antiprotons in the debuncher was measured using two methods during normal stacking conditions. With 2.3 seconds of cooling the vertical emittance was found to be 3.6 {pi} mm-mr using scraper D:TJ308, and 2.9 {pi} mm-mr using the profile on SEM806. With 6.9 seconds of cooling time time the measured horizontal emittance was 2.1 {pi} mm-mr using D:RJ306 v.s. 1.9 {pi} mm-mr using SEM806; but with 2.3 seconds of cooling the measured emittance in the debuncher was larger than in the DTOA line, 4.5 {pi} mm-mr v.s. 2.8 {pi} mm-mr. This suggests that some beam is being scraped on a horizontal aperture restriction someplace in the extraction process.

  9. Work functions of hafnium nitride thin films as emitter material for field emitter arrays

    SciTech Connect

    Gotoh, Yasuhito Fujiwara, Sho; Tsuji, Hiroshi

    2016-05-15

    The work functions of hafnium nitride thin films prepared by radio-frequency magnetron sputtering were investigated in vacuum, before and after surface cleaning processes, with a view of improving the properties of as-fabricated field emitter arrays comprising hafnium nitride emitters. The measurement of the work function was first performed for the as-deposited films and then for films subjected to surface cleaning process, either thermal treatment or ion bombardment. Thermal treatment at a maximum temperature of 300 °C reduced the work function by 0.7 eV. Once the film was heated, the work function maintained the reduced value, even after cooling to room temperature. A little change in the work function was observed for the second and third thermal treatments. The ion bombardment was conducted by exposing the sample to a thin plasma for different sample bias conditions and processing times. When the sample was biased at −10 V, the work function decreased by 0.6 eV. The work function reduction became saturated in the early stage of the ion bombardment. When the sample was biased at −50 V, the work function exhibited different behaviors, that is, first it decreased rapidly and then increased in response to the increase in processing time. The lowest attainable work function was found to be 4.00 eV. It should be noted that none of the work function values reported in this paper were obtained using surfaces that were demonstrated to be free from oxygen contamination. The present results suggest that the current–voltage characteristics of a field emitter array can be improved by a factor of 25–50 by the examined postprocesses.

  10. Sources of Emittance in RF Photocathode Injectors

    SciTech Connect

    Dowell, David

    2016-12-11

    Advances in electron beam technology have been central to creating the current generation of x-ray free electron lasers and ultra-fast electron microscopes. These once exotic devices have become essential tools for basic research and applied science. One important beam technology for both is the electron source which, for many of these instruments, is the photocathode RF gun. The invention of the photocathode gun and the concepts of emittance compensation and beam matching in the presence of space charge and RF forces have made these high-quality beams possible. Achieving even brighter beams requires a taking a finer resolution view of the electron dynamics near the cathode during photoemission and the initial acceleration of the beam. In addition, the high brightness beam is more sensitive to degradation by the optical aberrations of the gun’s RF and magnetic lenses. This paper discusses these topics including the beam properties due to fundamental photoemission physics, space charge effects close to the cathode, and optical distortions introduced by the RF and solenoid fields. Analytic relations for these phenomena are derived and compared with numerical simulations.

  11. HETDEX: Evolution of Lyman Alpha Emitters

    NASA Astrophysics Data System (ADS)

    Blanc, Guillermo A.; Gebhardt, K.; Hill, G. J.; Gronwall, C.; Ciardullo, R.; Finkelstein, S.; Gawiser, E.; HETDEX Collaboration

    2012-01-01

    The Hobby Eberly Telescope Dark Energy Experiment (HETDEX) will produce a sample of 800,000 Lyman Alpha Emitters (LAEs) over the 1.9

  12. An electron transporting blue emitter for OLED

    NASA Astrophysics Data System (ADS)

    Qi, Boyuan; Luo, Jiaxiu; Li, Suyue; Xiao, Lixin; Sun, Wenfang; Chen, Zhijian; Qu, Bo; Gong, Qihuang

    2010-11-01

    After the premier commercialization of OLED in 1997, OLED has been considered as the candidate for the next generation of flat panel display. In comparison to liquid crystal display (LCD) and plasma display panel (PDP), OLED exhibits promising merits for display, e.g., flexible, printable, micro-buildable and multiple designable. Although many efforts have been made on electroluminescent (EL) materials and devices, obtaining highly efficient and pure blue light is still a great challenge. In order to improve the emission efficiency and purity of the blue emission, a new bipolar blue light emitter, 2,7-di(2,2':6',2"-terpyridine)- 2,7-diethynyl-9,9-dioctyl-9H-fluorene (TPEF), was designed and synthesized. A blue OLED was obtained with the configuration of ITO/PEDOT/PVK:CBP:TPEF/LiF/Al. The device exhibits a turn-on voltage of 9 V and a maximum brightness of 12 cd/m2 at 15 V. The device gives a deep blue emission located at 420 nm with the Commission Internationale de l'Eclairage (CIE) coordinates of (0.17, 0.10). We also use TPEF as electron transporting material in the device of ITO/PPV/TPEF/LiF/Al, the turn-on voltage is 3 V. It is proved the current in the device was enhanced indeed by using the new material.

  13. Monolithic semiconductor light emitter and amplifier

    NASA Technical Reports Server (NTRS)

    Carlson, Nils W. (Inventor)

    1992-01-01

    A semiconductor light emitter comprising a substrate of a semiconductor material having a pair of opposed surfaces and a body of semiconductor material on one of the surfaces. The body includes a pair of clad layers of opposite conductivity types having an intermediate quantum well region therebetween. The clad layers are of a semiconductor material which forms a heterojunction with the material of the quantum well region. The clad layers and the quantum well region form a waveguide which extends along the body. A plurality of gain sections are formed in the body spaced along and optically coupled by the waveguide. Each of the gain sections is adapted to generate light therein when a voltage is placed thereacross. One of the gain section has gratings at each end thereof which are adapted to reflect light back into the one gain section and thereby create a beam of light. The grating between the one gain section and an adjacent gain section is adapted to allow some of the light generated in the one gain section to pass therethrough along the waveguide to the next gain section. Each of the other gain sections have gratings adjacent an end opposite the first gain sections. The periods of the grating are such that no self-oscillation of the light in the waveguide occurs so that each of the other gain sections serve as single pass amplifiers. The gratings also direct the amplified light from the other gain sections out of the body.

  14. Spectroscopic research on infrared emittance of coal ash deposits

    SciTech Connect

    Saljnikov, Aleksandar; Komatina, Mirko; Gojak, Milan; Vucicevic, Biljana; Goricanec, Darko; Stevanovic, Zoran

    2009-11-15

    This paper deals with thermal radiation characteristics of ash deposits on a pulverized coal combustion boiler of an electric power plant. Normal emittance spectra in the near to medium infrared (2.5-25 {mu}m) region and total normal emittances were measured on four kinds of ground ash deposits. Measurements were conducted in the 570-1460 K temperature range which is common for boiler furnaces, by both heating and cooling the ash samples, with the aim to study the effect of their thermal history. Dependence of emittance on wavelength, temperature and chemical composition was studied, too. Samples were tested for transparency (opacity) to verify the accuracy of results. It was determined that the thicknesses used for the ash powders are opaque for infrared radiation for thicknesses in the order of a millimeter. Tests have shown that spectral emittance increases with an increase of wavelength with a characteristic pattern common for all samples. Spectral normal emittance increases strongly with temperature at shorter wavelengths and remains high and unchanged at longer ones. Emittance spectra are not very sensitive to chemical composition of ashes especially beyond {lambda} {approx} 5 {mu}m. With an increase of temperature, total emittance of the powdered sample decreases to a minimum value around 1200 K. Further temperature rise induces an increase of total emittance due to sintering in the ash. On cooling, the emittance increases monotonically following the hysteresis. Quantitative directions for evaluating thermal radiation characteristics of ash deposits for the merits of the safety design of boiler furnaces were proposed. That comprises correlating the experimentally obtained emittance spectra with curves of simple analytical form, i.e., a continuous function of minimum emittance vs. wavelength. The proposed method can be extended to other specimens from the same furnace and used to determine correlations for thermal calculation of old and design of new furnaces

  15. Internal emitter limits for iodine, radium and radon daughters

    SciTech Connect

    Schlenker, R.A.

    1984-08-15

    This paper identifies some of the issues which arise in the consideration of the derivation of new limits on exposure to internal emitters. Basic and secondary radiation protection limits are discussed. Terms are defined and applied to the limitation of risk from stochastic effects. Non-stochastic data for specific internal emitters (/sup 131/I and the radium isotopes) are presented. Emphasis is placed on the quantitative aspects of the limit setting problem. 65 references, 2 figures, 12 tables.

  16. Study of ultra-low emittance design for SPEAR3

    SciTech Connect

    Wang, M. -H.; Huang, X.; Safranek, J.; /SLAC

    2015-09-17

    Since its 2003 construction, the SPEAR3 synchrotron light source at SLAC has continuously improved its performance by raising beam current, top-off injection, and smaller emittance. This makes SPEAR3 one of the most productive light sources in the world. Now, to further enhance the performance of SPEAR3, we are looking into the possibility of converting SPEAR3 to an ultra-low emittance storage ring within its site constraint.

  17. Bulk molybdenum field emitters by inductively coupled plasma etching.

    PubMed

    Zhu, Ningli; Cole, Matthew T; Milne, William I; Chen, Jing

    2016-12-07

    In this work we report on the fabrication of inductively coupled plasma (ICP) etched, diode-type, bulk molybdenum field emitter arrays. Emitter etching conditions as a function of etch mask geometry and process conditions were systematically investigated. For optimized uniformity, aspect ratios of >10 were achieved, with 25.5 nm-radius tips realised for masks consisting of aperture arrays some 4.45 μm in diameter and whose field electron emission performance has been herein assessed.

  18. Nanostructure TEM analysis of diamond cold cathode field emitters

    SciTech Connect

    Wade, Travis S.; Ghosh, Nikkon; Wittig, James Edward; Kang, Weng; Allard Jr, Lawrence Frederick; Unocic, Kinga A; Davidson, James; Tolk, Norman H.

    2012-01-01

    Diamond cold cathode devices have demonstrated significant potential as electron field emitters. Ultra-sharp diamond pyramidal tips (~5nm tip radius) have been fabricated and show improvement in emission when compared to conventional field emitters. However, the emission mechanisms in these complex diamond nanostructures are not well understood. Transmission electron microscopy performed in this study provides new insight into tip structure and composition with implications for field emission and diamond growth.

  19. A Smart Microwave Vacuum Electron Device (MVED) Using Field Emitters

    DTIC Science & Technology

    2012-01-31

    Stellar Lateral Emitters The original program was based on receiving lateral, nano -layer carbon emitters from Stellar Micro Devices (SMD). Stellar...Leakage current in the cathodes have been a very large problem. With an increased leakage both the heat of the cathode and voltage drop across...perfom1ance. The tleld emission arrays intended for the experiment did not meet specifications, so alternative field emission cathodes were used. While these

  20. Electromagnetic compatibility of implantable neurostimulators to RFID emitters

    PubMed Central

    2011-01-01

    Background The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters. Methods Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz Results The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. Conclusions The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters. PMID:21658266

  1. Validated Analytical Model of a Pressure Compensation Drip Irrigation Emitter

    NASA Astrophysics Data System (ADS)

    Shamshery, Pulkit; Wang, Ruo-Qian; Taylor, Katherine; Tran, Davis; Winter, Amos

    2015-11-01

    This work is focused on analytically characterizing the behavior of pressure-compensating drip emitters in order to design low-cost, low-power irrigation solutions appropriate for off-grid communities in developing countries. There are 2.5 billion small acreage farmers worldwide who rely solely on their land for sustenance. Drip, compared to flood, irrigation leads to up to 70% reduction in water consumption while increasing yields by 90% - important in countries like India which are quickly running out of water. To design a low-power drip system, there is a need to decrease the pumping pressure requirement at the emitters, as pumping power is the product of pressure and flow rate. To efficiently design such an emitter, the relationship between the fluid-structure interactions that occur in an emitter need to be understood. In this study, a 2D analytical model that captures the behavior of a common drip emitter was developed and validated through experiments. The effects of independently changing the channel depth, channel width, channel length and land height on the performance were studied. The model and the key parametric insights presented have the potential to be optimized in order to guide the design of low-pressure, clog-resistant, pressure-compensating emitters.

  2. Electromagnetic compatibility of implantable neurostimulators to RFID emitters.

    PubMed

    Pantchenko, Oxana S; Seidman, Seth J; Guag, Joshua W; Witters, Donald M; Sponberg, Curt L

    2011-06-09

    The objective of this study is to investigate electromagnetic compatibility (EMC) of implantable neurostimulators with the emissions from radio frequency identification (RFID) emitters. Six active implantable neurostimulators with lead systems were tested for susceptibility to electromagnetic fields generated by 22 RFID emitters. These medical devices have been approved for marketing in the U.S. for a number of intended uses that include: epilepsy, depression, incontinence, Parkinsonian tremor and pain relief. Each RFID emitter had one of the following carrier frequencies: 125 kHz, 134 kHz, 13.56 MHz, 433 MHz, 915 MHz and 2.45 GHz. The test results showed the output of one of the implantable neurostimulators was inhibited by 134 kHz RFID emitter at separation distances of 10 cm or less. The output of the same implantable neurostimulator was also inhibited by another 134 kHz RFID emitter at separation distances of 10 cm or less and also showed inconsistent pulsing rate at a separation distance of 15 cm. Both effects occurred during and lasted through out the duration of the exposure. The clinical significance of the effects was assessed by a clinician at the U.S. Food and Drug Administration. The effects were determined to be clinically significant only if they occurred for extended period of time. There were no observed effects from the other 5 implantable neurostimulators or during exposures from other RFID emitters.

  3. A thermionic energy converter with an electrolytically etched tungsten emitter

    SciTech Connect

    Gubbels, G.H.M.; Metselaar, R. )

    1990-08-15

    The bare work functions of etched and unetched plasma-sprayed tungsten were found to be 4.8 and 4.5 eV, respectively. The electron emission of plasma-sprayed tungsten, both etched and unetched, was measured over a wide range of temperatures in a cesium atmosphere. Work functions were derived from the saturation current densities. In the ignited mode, current-voltage ({ital I}-{ital V}) characteristics were measured. The influence of the emitter, collector, and cesium reservoir temperatures on the {ital I}-{ital V} characteristics was investigated. Barrier indexes of 2.06 and 2.30 eV were found for etched and unetched tungsten emitters, respectively. At an emitter temperature of 1400 {degree}C, in the case of an unetched tungsten emitter a power density of 1.5 W/cm{sup 2} was found, while for an etched tungsten emitter it was 4.5 W/cm{sup 2}. This increased power density could be attributed to a lower collector work function. The lower cesiated collector work function resulted from the evaporation of oxygen, as WO{sub 3}, from the etched tungsten emitter.

  4. Chemiexcitation induced proton transfer: enolate oxyluciferin as the firefly bioluminophore.

    PubMed

    Pinto da Silva, Luís; Esteves da Silva, Joaquim C G

    2015-02-12

    Firefly bioluminescence is a phenomenon that attracts attention from the research community because of complex challenges for fundamental investigation, as well as diverse opportunities for practical application. Here we have studied the potential deprotonation of firefly oxyluciferin by using a theoretical approach in an enzymatic-like microenvironment in chemiexcited proton transfer involving adenosine 5'-monophosphate. We have uncovered a reaction route that links the evidence that the light-emitter is an anionic molecule while it is chemiexcited in its neutral form. Moreover, the results indicated that the anionic bioluminophore is the enolate anion and not the ketonic one. Further calculations supported this identification of the light-emitter: the spectrum of resulting enolate anion covers the entire yellow-green/red bioluminescence range, which is in line with the experimental findings regarding firefly multicolor bioluminescence.

  5. Decoupling intensity radiated by the emitter in distance estimation from camera to IR emitter.

    PubMed

    Cano-García, Angel E; Galilea, José Luis Lázaro; Fernández, Pedro; Infante, Arturo Luis; Pompa-Chacón, Yamilet; Vázquez, Carlos Andrés Luna

    2013-05-31

    Various models using radiometric approach have been proposed to solve the problem of estimating the distance between a camera and an infrared emitter diode (IRED). They depend directly on the radiant intensity of the emitter, set by the IRED bias current. As is known, this current presents a drift with temperature, which will be transferred to the distance estimation method. This paper proposes an alternative approach to remove temperature drift in the distance estimation method by eliminating the dependence on radiant intensity. The main aim was to use the relative accumulated energy together with other defined models, such as the zeroth-frequency component of the FFT of the IRED image and the standard deviation of pixel gray level intensities in the region of interest containing the IRED image. By using the abovementioned models, an expression free of IRED radiant intensity was obtained. Furthermore, the final model permitted simultaneous estimation of the distance between the IRED and the camera and the IRED orientation angle. The alternative presented in this paper gave a 3% maximum relative error over a range of distances up to 3 m.

  6. Decoupling Intensity Radiated by the Emitter in Distance Estimation from Camera to IR Emitter

    PubMed Central

    Cano-García, Angel E.; Galilea, José Luis Lázaro; Fernández, Pedro; Infante, Arturo Luis; Pompa-Chacón, Yamilet; Vázquez, Carlos Andrés Luna

    2013-01-01

    Various models using radiometric approach have been proposed to solve the problem of estimating the distance between a camera and an infrared emitter diode (IRED). They depend directly on the radiant intensity of the emitter, set by the IRED bias current. As is known, this current presents a drift with temperature, which will be transferred to the distance estimation method. This paper proposes an alternative approach to remove temperature drift in the distance estimation method by eliminating the dependence on radiant intensity. The main aim was to use the relative accumulated energy together with other defined models, such as the zeroth-frequency component of the FFT of the IRED image and the standard deviation of pixel gray level intensities in the region of interest containing the IRED image. By using the abovementioned models, an expression free of IRED radiant intensity was obtained. Furthermore, the final model permitted simultaneous estimation of the distance between the IRED and the camera and the IRED orientation angle. The alternative presented in this paper gave a 3% maximum relative error over a range of distances up to 3 m. PMID:23727954

  7. Elastic proton-proton scattering at RHIC

    SciTech Connect

    Yip, K.

    2011-09-03

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

  8. Proton pump inhibitors

    MedlinePlus

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

  9. What's In a Proton?

    ScienceCinema

    Brookhaven Lab

    2016-07-12

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

  10. What's In a Proton?

    SciTech Connect

    Brookhaven Lab

    2009-07-08

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

  11. Silicon Carbide Emitter Turn-Off Thyristor

    DOE PAGES

    Wang, Jun; Wang, Gangyao; Li, Jun; ...

    2008-01-01

    A novel MOS-conmore » trolled SiC thyristor device, the SiC emitter turn-off thyristor (ETO) is a promising technology for future high-voltage switching applications because it integrates the excellent current conduction capability of a SiC thyristor with a simple MOS-control interface. Through unity-gain turn-off, the SiC ETO also achieves excellent Safe Operation Area (SOA) and faster switching speeds than silicon ETOs. The world's first 4.5-kV SiC ETO prototype shows a forward voltage drop of 4.26 V at 26.5  A / cm 2 current density at room and elevated temperatures. Tested in an inductive circuit with a 2.5 kV DC link voltage and a 9.56-A load current, the SiC ETO shows a fast turn-off time of 1.63 microseconds and a low 9.88 mJ turn-off energy. The low switching loss indicates that the SiC ETO could operate at about 4 kHz if 100  W / cm 2 conduction and the 100  W / cm 2 turn-off losses can be removed by the thermal management system. This frequency capability is about 4 times higher than 4.5-kV-class silicon power devices. The preliminary demonstration shows that the SiC ETO is a promising candidate for high-frequency, high-voltage power conversion applications, and additional developments to optimize the device for higher voltage (>5 kV) and higher frequency (10 kHz) are needed.« less

  12. Barium Depletion in Hollow Cathode Emitters

    NASA Technical Reports Server (NTRS)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  13. Novalike cataclysmic variables are significant radio emitters

    NASA Astrophysics Data System (ADS)

    Coppejans, Deanne L.; Körding, Elmar G.; Miller-Jones, James C. A.; Rupen, Michael P.; Knigge, Christian; Sivakoff, Gregory R.; Groot, Paul J.

    2015-08-01

    Radio emission from non-magnetic cataclysmic variables (CVs, accreting white dwarfs) could allow detailed studies of outflows and possibly accretion flows in these nearby, numerous and non-relativistic compact accretors. Up to now, however, very few CVs have been detected in the radio. We have conducted a Very Large Array pilot survey of four close and optically bright novalike CVs at 6 GHz, detecting three, and thereby doubling the number of radio detections of these systems. TT Ari, RW Sex and the old nova V603 Aql were detected in both of the epochs, while V1084 Her was not detected (to a 3σ upper limit of 7.8 μ {Jy} {beam}^{-1}). These observations clearly show that the sensitivity of previous surveys was typically too low to detect these objects and that non-magnetic CVs can indeed be significant radio emitters. The three detected sources show a range of properties, including flaring and variability on both short (˜200 s) and longer term (days) time-scales, as well as circular polarization levels of up to 100 per cent. The spectral indices range from steep to inverted; TT Ari shows a spectral turnover at ˜6.5 GHz, while the spectral index of V603 Aql flattened from α = 0.54 ± 0.05 to 0.16 ± 0.08 (Fν ∝ να) in the week between observations. This range of properties suggests that more than one emission process can be responsible for the radio emission in non-magnetic CVs. In this sample we find that individual systems are consistent with optically thick synchrotron emission, gyrosynchrotron emission or cyclotron maser emission.

  14. Enhanced proton acceleration by intense laser interaction with an inverse cone target

    SciTech Connect

    Bake, Muhammad Ali; Aimidula, Aimierding Xiaerding, Fuerkaiti; Rashidin, Reyima

    2016-08-15

    The generation and control of high-quality proton bunches using focused intense laser pulse on an inverse cone target is investigated with a set of particle-in-cell simulations. The inverse cone is a high atomic number conical frustum with a thin solid top and open base, where the laser impinges onto the top surface directly, not down the open end of the cone. Results are compared with a simple planar target, where the proton angular distribution is very broad because of transverse divergence of the electromagnetic fields behind the target. For a conical target, hot electrons along the cone wall surface induce a transverse focusing sheath field. This field can effectively suppress the spatial spreading of the protons, resulting in a high-quality small-emittance, low-divergence proton beam. A slightly lower proton beam peak energy than that of a conventional planar target was also found.

  15. Enhanced proton acceleration by intense laser interaction with an inverse cone target

    NASA Astrophysics Data System (ADS)

    Bake, Muhammad Ali; Aimidula, Aimierding; Xiaerding, Fuerkaiti; Rashidin, Reyima

    2016-08-01

    The generation and control of high-quality proton bunches using focused intense laser pulse on an inverse cone target is investigated with a set of particle-in-cell simulations. The inverse cone is a high atomic number conical frustum with a thin solid top and open base, where the laser impinges onto the top surface directly, not down the open end of the cone. Results are compared with a simple planar target, where the proton angular distribution is very broad because of transverse divergence of the electromagnetic fields behind the target. For a conical target, hot electrons along the cone wall surface induce a transverse focusing sheath field. This field can effectively suppress the spatial spreading of the protons, resulting in a high-quality small-emittance, low-divergence proton beam. A slightly lower proton beam peak energy than that of a conventional planar target was also found.

  16. Spectroscopy at the two-proton drip line: Excited states in 158W

    NASA Astrophysics Data System (ADS)

    Joss, D. T.; Page, R. D.; Herzán, A.; Donosa, L.; Uusitalo, J.; Carroll, R. J.; Darby, I. G.; Andgren, K.; Cederwall, B.; Eeckhaudt, S.; Grahn, T.; Greenlees, P. T.; Hadinia, B.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Leino, M.; Leppanen, A.-P.; Nyman, M.; O'Donnell, D.; Pakarinen, J.; Rahkila, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Seweryniak, D.; Simpson, J.; Sorri, J.

    2017-09-01

    Excited states have been identified in the heaviest known even-Z N = 84 isotone 158W, which lies in a region of one-proton emitters and the two-proton drip line. The observation of γ-ray transitions feeding the ground state establishes the excitation energy of the yrast 6+ state confirming the spin-gap nature of the α-decaying 8+ isomer. The 8+ isomer is also expected to be unbound to two-proton emission but no evidence for this decay mode was observed. An upper limit for the two-proton decay branch has been deduced as b2p ≤ 0.17% at the 90% confidence level. The possibility of observing two-proton emission from multiparticle isomers in nearby nuclides is considered.

  17. Proton: the particle.

    PubMed

    Suit, Herman

    2013-11-01

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

  18. Proton: The Particle

    SciTech Connect

    Suit, Herman

    2013-11-01

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

  19. Interstellar protonated molecular species

    NASA Astrophysics Data System (ADS)

    Etim, Emmanuel E.; Gorai, Prasanta; Das, Ankan; Arunan, Elangannan

    2017-08-01

    Majority of the known interstellar cations are protonated species believed to be the natural precursors for their corresponding neutral analogues formed via the dissociative recombination process. The protonation of a neutral species can occur in more than one position on the molecular structure thus resulting in more than one proton binding energy value and different protonated species for the same neutral species. In the present work, ab initio quantum calculations are employed to calculate accurate proton binding energies for over 100 neutral interstellar molecules of which majority of the neutral molecules are protonated in more than one position. From the results, protonated species resulting from a high proton binding energy prefers to remain protonated rather than transferring a proton and returning to its neutral form as compared to its analogue that gives rise to a lower proton binding energy (PBE) from the same neutral species. For two protonated species resulting from the same neutral molecule, the one that results in a higher PBE is more stable as compared to its counterpart that is responsible for the lower PBE for the same neutral species. Here, the most stable species are highlighted for all the systems considered.

  20. Fermilab HINS Proton Ion Source Beam Measurements

    SciTech Connect

    Tam, W.M.; Apollinari, G.; Chaurize, S.; Hays, S.; Romanov, G.; Scarpine, V.; Schmidt, C.; Webber, R.; /Fermilab

    2009-05-01

    The proton ion source for the High Intensity Neutrino Source (HINS) Linac front-end at Fermilab has been successfully commissioned. It produces a 50 keV, 3 msec beam pulse with a peak current greater than 20mA at 2.5Hz. The beam is transported to the radio-frequency quadrupole (RFQ) by a low energy beam transport (LEBT) that consists of two focusing solenoids, four steering dipole magnets and a beam current transformer. To understand beam transmission through the RFQ, it is important to characterize the 50 keV beam before connecting the LEBT to the RFQ. A wire scanner and a Faraday cup are temporarily installed at the exit of the LEBT to study the beam parameters. Beam profile measurements are made for different LEBT settings and results are compared to those from computer simulations. In lieu of direct emittance measurements, solenoid variation method based on profile measurements is used to reconstruct the beam emittance.

  1. Emittance and Phase Space Tomography for the Fermilab Linac

    SciTech Connect

    Garcia, F.G.G.; Johnstone, C.; Kobilarcik, T.; Koizumi, G.M.; Moore, C.D.; Newhart, D.L.; /Fermilab

    2012-05-01

    The Fermilab Linac delivers a variable intensity, 400-MeV beam to the MuCool Test Area experimental hall via a beam line specifically designed to facilitate measurements of the Linac beam emittance and properties. A 10 m, dispersion-free and magnet-free straight utilizes an upstream quadrupole focusing triplet in combination with the necessary in-straight beam diagnostics to fully characterize the transverse beam properties. Since the Linac does not produce a strictly elliptical phase space, tomography must be performed on the profile data to retrieve the actual particle distribution in phase space. This is achieved by rotating the phase space distribution using different waist focusing conditions of the upstream triplet and performing a deconvolution of the profile data. Preliminary measurements using this diagnostic section are reported here. These data represent a first-pass measurement of the Linac emittance based on various techniques. It is clear that the most accurate representation of the emittance is given by the 3-profile approach. Future work will entail minimizing the beam spot size on MW5 to test and possibly improve the accuracy of the 2-profile approach. The 95% emittance is {approx} 18{pi} in the vertical and {approx} 13{pi} in the horizontal, which is especially larger than anticipated - 8-10{pi} was expected. One possible explanation is that the entire Linac pulse is extracted into the MTA beamline and during the first few microseconds, the feed forward and RF regulation are not stable. This may result in a larger net emittance observed versus beam injected into Booster, where the leading part of the Linac beam pulse is chopped. Future studies will clearly entail a measurement of the emittance vs. pulse length. One additional concern is that the Linac phase space is most likely aperture-defined and non-elliptical in nature. A non-elliptical phase-space determination would require a more elaborate analysis and provide another explanation of the

  2. Nanostructure-Induced Distortion in Single-Emitter Microscopy.

    PubMed

    Lim, Kangmook; Ropp, Chad; Barik, Sabyasachi; Fourkas, John; Shapiro, Benjamin; Waks, Edo

    2016-09-14

    Single-emitter microscopy has emerged as a promising method of imaging nanostructures with nanoscale resolution. This technique uses the centroid position of an emitter's far-field radiation pattern to infer its position to a precision that is far below the diffraction limit. However, nanostructures composed of high-dielectric materials such as noble metals can distort the far-field radiation pattern. Previous work has shown that these distortions can significantly degrade the imaging of the local density of states in metallic nanowires using polarization-resolved imaging. But unlike nanowires, nanoparticles do not have a well-defined axis of symmetry, which makes polarization-resolved imaging difficult to apply. Nanoparticles also exhibit a more complex range of distortions, because in addition to introducing a high dielectric surface, they also act as efficient scatterers. Thus, the distortion effects of nanoparticles in single-emitter microscopy remains poorly understood. Here we demonstrate that metallic nanoparticles can significantly distort the accuracy of single-emitter imaging at distances exceeding 300 nm. We use a single quantum dot to probe both the magnitude and the direction of the metallic nanoparticle-induced imaging distortion and show that the diffraction spot of the quantum dot can shift by more than 35 nm. The centroid position of the emitter generally shifts away from the nanoparticle position, which is in contradiction to the conventional wisdom that the nanoparticle is a scattering object that will pull in the diffraction spot of the emitter toward its center. These results suggest that dielectric distortion of the emission pattern dominates over scattering. We also show that by monitoring the distortion of the quantum dot diffraction spot we can obtain high-resolution spatial images of the nanoparticle, providing a new method for performing highly precise, subdiffraction spatial imaging. These results provide a better understanding of the

  3. Nanostructure-Induced Distortion in Single-Emitter Microscopy

    NASA Astrophysics Data System (ADS)

    Lim, Kangmook; Ropp, Chad; Barik, Sabyasachi; Fourkas, John; Shapiro, Benjamin; Waks, Edo

    2016-09-01

    Single-emitter microscopy has emerged as a promising method of imaging nanostructures with nanoscale resolution. This technique uses the centroid position of an emitters far-field radiation pattern to infer its position to a precision that is far below the diffraction limit. However, nanostructures composed of high-dielectric materials such as noble metals can distort the far-field radiation pattern. Nanoparticles also exhibit a more complex range of distortions, because in addition to introducing a high dielectric surface, they also act as efficient scatterers. Thus, the distortion effects of nanoparticles in single-emitter microscopy remains poorly understood. Here we demonstrate that metallic nanoparticles can significantly distort the accuracy of single-emitter imaging at distances exceeding 300 nm. We use a single quantum dot to probe both the magnitude and the direction of the metallic nanoparticle-induced imaging distortion and show that the diffraction spot of the quantum dot can shift by more than 35 nm. The centroid position of the emitter generally shifts away from the nanoparticle position, in contradiction to the conventional wisdom that the nanoparticle is a scattering object that will pull in the diffraction spot of the emitter towards its center. These results suggest that dielectric distortion of the emission pattern dominates over scattering. We also show that by monitoring the distortion of the quantum dot diffraction spot we can obtain high-resolution spatial images of the nanoparticle, providing a new method for performing highly precise, sub-diffraction spatial imaging. These results provide a better understanding of the complex near-field coupling between emitters and nanostructures, and open up new opportunities to perform super-resolution microscopy with higher accuracy.

  4. Proton-decaying, light nuclei accessed via the invariant-mass method

    NASA Astrophysics Data System (ADS)

    Brown, Kyle

    2017-01-01

    Two-nucleon decay is the most recently discovered nuclear decay mode. For proton-rich nuclei, the majority of multi-proton decays occur via sequential steps of one-proton emission. Direct two-proton (2p) decay was believed to occur only in even-Z nuclei beyond the proton drip line where one-proton decay is energy forbidden. This has been observed for the ground states of around a dozen nuclei including 6Be, the lightest case, and 54Zn, the heaviest case. Direct 2p decay has also recently been observed for isobaric analog states where all possible 1p intermediates are either isospin allowed and energy forbidden, or energy-allowed and isospin forbidden. For light proton emitters, the lifetimes are short enough that the invariant-mass technique is ideal for measuring the decay energy, intrinsic width and, for multi-proton decays, the momentum correlations between the fragments. I will describe recent measurements of proton emitters using the invariant-mass technique with the High Resolution Array (HiRA). I will present a new, high-statistics measurement on the sequential 2p decay of excited states in 17Ne. Measuring the momentum correlations between the decay fragments allow us to determine the 1p intermediate state through which the decay proceeds. I will present data on the isobaric-analog pair 8C and 8BIAS, which highlight the two known types of direct 2p decay. I will also present the first observation of 17Na, which is unbound with respect to three-proton emission. Finally I will present a new measurement on the width of the first-excited state of 9C and compare to recent theoretical calculations.

  5. High intensity electron cyclotron resonance proton source for low energy high intensity proton accelerator.

    PubMed

    Roychowdhury, P; Chakravarthy, D P

    2009-12-01

    Electron cyclotron resonance (ECR) proton source at 50 keV, 50 mA has been designed, developed, and commissioned for the low energy high intensity proton accelerator (LEHIPA). Plasma characterization of this source has been performed. ECR plasma was generated with 400-1100 W of microwave power at 2.45 GHz, with hydrogen as working gas. Microwave was fed in the plasma chamber through quartz window. Plasma density and temperature was studied under various operating conditions, such as microwave power and gas pressure. Langmuir probe was used for plasma characterization using current voltage variation. The typical hydrogen plasma density and electron temperature measured were 7x10(11) cm(-3) and 6 eV, respectively. The total ion beam current of 42 mA was extracted, with three-electrode extraction geometry, at 40 keV of beam energy. The extracted ion current was studied as a function of microwave power and gas pressure. Depending on source pressure and discharge power, more than 30% total gas efficiency was achieved. The optimization of the source is under progress to meet the requirement of long time operation. The source will be used as an injector for continuous wave radio frequency quadrupole, a part of 20 MeV LEHIPA. The required rms normalized emittance of this source is less than 0.2 pi mm mrad. The simulated value of normalized emittance is well within this limit and will be measured shortly. This paper presents the study of plasma parameters, first beam results, and the status of ECR proton source.

  6. High intensity electron cyclotron resonance proton source for low energy high intensity proton accelerator

    SciTech Connect

    Roychowdhury, P.; Chakravarthy, D. P.

    2009-12-15

    Electron cyclotron resonance (ECR) proton source at 50 keV, 50 mA has been designed, developed, and commissioned for the low energy high intensity proton accelerator (LEHIPA). Plasma characterization of this source has been performed. ECR plasma was generated with 400-1100 W of microwave power at 2.45 GHz, with hydrogen as working gas. Microwave was fed in the plasma chamber through quartz window. Plasma density and temperature was studied under various operating conditions, such as microwave power and gas pressure. Langmuir probe was used for plasma characterization using current voltage variation. The typical hydrogen plasma density and electron temperature measured were 7x10{sup 11} cm{sup -3} and 6 eV, respectively. The total ion beam current of 42 mA was extracted, with three-electrode extraction geometry, at 40 keV of beam energy. The extracted ion current was studied as a function of microwave power and gas pressure. Depending on source pressure and discharge power, more than 30% total gas efficiency was achieved. The optimization of the source is under progress to meet the requirement of long time operation. The source will be used as an injector for continuous wave radio frequency quadrupole, a part of 20 MeV LEHIPA. The required rms normalized emittance of this source is less than 0.2 {pi} mm mrad. The simulated value of normalized emittance is well within this limit and will be measured shortly. This paper presents the study of plasma parameters, first beam results, and the status of ECR proton source.

  7. Capture and Transport of Laser Accelerated Protons by Pulsed Magnetic Fields: Advancements Toward Laser-Based Proton Therapy

    NASA Astrophysics Data System (ADS)

    Burris-Mog, Trevor J.

    The interaction of intense laser light (I > 10 18 W/cm2) with a thin target foil leads to the Target Normal Sheath Acceleration mechanism (TNSA). TNSA is responsible for the generation of high current, ultra-low emittance proton beams, which may allow for the development of a compact and cost effective proton therapy system for the treatment of cancer. Before this application can be realized, control is needed over the large divergence and the 100% kinetic energy spread that are characteristic of TNSA proton beams. The work presented here demonstrates control over the divergence and energy spread using strong magnetic fields generated by a pulse power solenoid. The solenoidal field results in a parallel proton beam with a kinetic energy spread DeltaE/E = 10%. Assuming that next generation lasers will be able to operate at 10 Hz, the 10% spread in the kinetic energy along with the 23% capture efficiency of the solenoid yield enough protons per laser pulse to, for the first time, consider applications in Radiation Oncology. Current lasers can generate proton beams with kinetic energies up to 67.5 MeV, but for therapy applications, the proton kinetic energy must reach 250 MeV. Since the maximum kinetic energy Emax of the proton scales with laser light intensity as Emax ∝ I0.5, next generation lasers may very well accelerate 250 MeV protons. As the kinetic energy of the protons is increased, the magnetic field strength of the solenoid will need to increase. The scaling of the magnetic field B with the kinetic energy of the protons follows B ∝ E1/2. Therefor, the field strength of the solenoid presented in this work will need to be increased by a factor of 2.4 in order to accommodate 250 MeV protons. This scaling factor seems reasonable, even with present technology. This work not only demonstrates control over beam divergence and energy spread, it also allows for us to now perform feasibility studies to further research what a laser-based proton therapy system

  8. Transverse emittance dilution due to coupler kicks in linear accelerators

    NASA Astrophysics Data System (ADS)

    Buckley, Brandon; Hoffstaetter, Georg H.

    2007-11-01

    One of the main concerns in the design of low emittance linear accelerators (linacs) is the preservation of beam emittance. Here we discuss one possible source of emittance dilution, the coupler kick, due to transverse electromagnetic fields in the accelerating cavities of the linac caused by the power coupler geometry. In addition to emittance growth, the coupler kick also produces orbit distortions. It is common wisdom that emittance growth from coupler kicks can be strongly reduced by using two couplers per cavity mounted opposite each other or by having the couplers of successive cavities alternate from above to below the beam pipe so as to cancel each individual kick. While this is correct, including two couplers per cavity or alternating the coupler location requires large technical changes and increased cost for superconducting cryomodules where cryogenic pipes are arranged parallel to a string of several cavities. We therefore analyze consequences of alternate coupler placements. We show here that alternating the coupler location from above to below compensates the emittance growth as well as the orbit distortions. For sufficiently large Q values, alternating the coupler location from before to after the cavity leads to a cancellation of the orbit distortion but not of the emittance growth, whereas alternating the coupler location from before and above to behind and below the cavity cancels the emittance growth but not the orbit distortion. We show that cancellations hold for sufficiently large Q values. These compensations hold even when each cavity is individually detuned, e.g., by microphonics. Another effective method for reducing coupler kicks that is studied is the optimization of the phase of the coupler kick so as to minimize the effects on emittance from each coupler. This technique is independent of the coupler geometry but relies on operating on crest. A final technique studied is symmetrization of the cavity geometry in the coupler region with

  9. Joint Lyman α emitters - quasars reionization constraints

    NASA Astrophysics Data System (ADS)

    Baek, S.; Ferrara, A.; Semelin, B.

    2012-06-01

    We present a novel method to investigate c reionization, using joint spectral information on high-redshift Lyman α emitters (LAEs) and quasi-stellar objects (QSOs). Although LAEs have been proposed as reionization probes, their use is hampered by the fact their Lyα line is damped not only by intergalactic H I but also internally by dust. Our method allows us to overcome such degeneracy. First, we carefully calibrate a reionization simulation with QSO absorption line experiments. Then we identify LAEs (? and equivalent width >20 Å) in two simulation boxes at z= 5.7 and 6.6 and we build synthetic images/spectra of a prototypical LAE. The surface brightness maps show the presence of a scattering halo extending up to 150 kpc from the galaxye. For each LAE we then select a small box of (10 h-1 Mpc)3 around it and derive the optical depth τ along three viewing axes. At redshift 5.7, we find that the Lyα transmissivity ?, almost independent of the halo mass. This constancy arises from the conspiracy of two effects: (i) the intrinsic Lyα line width and (ii) the infall peculiar velocity. At higher redshift, z= 6.6, where ? the transmissivity is instead largely set by the local H I abundance and ? consequently increases with halo mass, Mh, from 0.15 to 0.3. Although outflows are present, they are efficiently pressure confined by infall in a small region around the LAE; hence they only marginally affect transmissivity. Finally, we cast line of sight originating from background QSOs passing through foreground LAEs at different impact parameters, and compute the quasar transmissivity (?). At small impact parameters, d < 1 cMpc, a positive correlation between ? and Mh is found at z= 5.7, which tends to become less pronounced (i.e. flatter) at larger distances. Quantitatively, a roughly 10× increase (from 5 × 10-3 to 6 × 10-2) of ? is observed in the range log Mh= (10.4-11.6). This correlation becomes even stronger at z= 6.6. By cross-correlating ? and ?, we can obtain a

  10. Modeling field emitter arrays using nonlinear line charge distribution

    NASA Astrophysics Data System (ADS)

    Biswas, Debabrata; Singh, Gaurav; Kumar, Raghwendra

    2016-09-01

    Modeling high aspect ratio field emitter arrays is a computational challenge due to the enormity of the resources involved. The line charge model (LCM) provides an alternate semi-analytical tool that has been used to model both infinite as well as finite sized arrays. It is shown that the linearly varying charge density used in the LCM generically mimics ellipsoidal emitters rather than a Cylindrical-Post-with-an-Ellipsoidal-Tip (CPET) that is typical of nanowires. Furthermore, generalizing the charge density beyond the linear regime allows for modeling shapes that are closer to a CPET. Emitters with a fixed base radius and a fixed apex radius are studied with a view to understanding the effect of nonlinearity on the tip enhancement factor and the emitter current in each case. Furthermore, an infinite square array of the CPET emitters is studied using the nonlinear line charge model, each having a height h =1500 μm and a base radius b =1.5 μm . It is found that for moderate external field strengths ( 0.3 -0.4 V /μm ), the array current density falls sharply for lattice spacings smaller than 4/3 h . Beyond this value, the maximal array current density can be observed over a range of lattice spacings and falls gradually thereafter.

  11. RF gun emittance correction using unsymmetrical RF cavities

    NASA Astrophysics Data System (ADS)

    Serafini, L.; Rivolta, R.; Terzoli, L.; Pagani, C.

    1992-07-01

    The beam dynamics in RF guns is characterized by an optimum injection phase which minimizes the RF-field-induced emittance blowup: such a condition corresponds to a vanishing first order term in the phase dependence of the exit transverse momentum. Away from the optimum phase, a sharp increase of the emittance is found. In this paper we analyze the possibility of compensating for both the first and second order terms, in order to recover the minimum emittance value even at phases different from the optimum one. Our scheme is based on the use of an unsymmetrical RF cavity, added downstream of the gun cavity and fully uncoupled from it, in order to be independently phased. At the exit of this cavity the minimum emittance value can be recovered, the injection phase being a free parameter to be independently optimized. In this way higher injection phases can be exploited, where the longitudinal rms emittance displays a minimum, and long bunches extracted from the gun can be magnetically compressed more efficiently, achieving a significant beam brightness increase with respect to conventionally optimized RF guns. An analytical study of the beam dynamics inside the unsymmetrical RF cavity is presented, together with the results of some numerical simulations performed with the PIC code ITACA [L. Serafini and C. Pagani, Proc. 1st EPAC, Rome, June 1988 (Word Scientific) p. 866].

  12. Study of Abnormal Vertical Emittance Growth in ATF Extraction Line

    SciTech Connect

    Alabau, M.; Faus-Golfe, A.; Alabau, M.; Bambade, P.; Brossard, J.; Le Meur, G.; Rimbault, C.; Touze, F.; Angal-Kalinin, D.; Jones, J.K.; Appleby, R.; Scarfe, A.; Kuroda, S.; White, G.R.; Woodley, M.; Zimmermann, F.; /CERN

    2011-11-04

    Since several years, the vertical beam emittance measured in the Extraction Line (EXT) of the Accelerator Test Facility (ATF) at KEK, that will transport the electron beam from the ATF Damping Ring (DR) to the future ATF2 Final Focus beam line, is significantly larger than the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam intensity. This longstanding problem has motivated studies of possible sources of this anomalous emittance growth. One possible contribution is non-linear magnetic fields in the extraction region experimented by the beam while passing off-axis through magnets of the DR during the extraction process. In this paper, simulations of the emittance growth are presented and compared to observations. These simulations include the effects of predicted non-linear field errors in the shared DR magnets and orbit displacements from the reference orbit in the extraction region. Results of recent measurements using closed orbit bumps to probe the relation between the extraction trajectory and the anomalous emittance growth are also presented.

  13. Fabrication of VO2-based multilayer structure with variable emittance

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Cao, Yunzhen; Zhang, Yuzhi; Yan, Lu; Li, Ying

    2015-07-01

    VO2 film holds promise for smart radiation device (SRD) use because of its infrared reflection change through the semiconductor-to-metal transition (SMT). In present study, a multilayer structure which consisted of VO2 layer, HfO2 layer and Ag layer was fabricated to achieve variable emittance based on the principle of reflection filter and SMT of VO2. It was found that with optimal 50 nm-thick VO2 layer, emittance of the multilayer structure could reversibly change from 0.13 at 30 °C to 0.68 at 80 °C with emittance variability of 0.55. Emittance hysteresis loop with transition temperature (Tc) of 58 °C and narrow width of 4 °C was obtained. Finally, multilayer structures with W-doped VO2 films were deposited and transition temperature decreased from 58 to 5 °C as W doping concentration increased from 0% to 3%, with Tc decreasing efficiency of -17.2 °C/at%. However, W doping also led to increased low temperature infrared absorption of VO2 film, which resulted in decreased emittance variability for the multilayer structure, from 0.55 to 0.37 as the W doping concentration in VO2 layer increase from 0% to 3%.

  14. Study of Lower Emittance Lattices for SPEAR3

    SciTech Connect

    Huang, Xiaobiao; Nosochkov, Yuri; Safranek, James A.; Wang, Lanfa; /SLAC

    2011-11-08

    We study paths to significantly reduce the emittance of the SPEAR3 storage ring. Lattice possibilities are explored with the GLASS technique. New lattices are designed and optimized for practical dynamic aperture and beam lifetime. Various techniques are employed to optimize the nonlinear dynamics, including the Elegant-based genetic algorithm. Experimental studies are also carried out on the ring to validate the lattice design. The SPEAR3 storage ring is a third generation light source which has a racetrack layout with a circumference of 234.1 m. The requirement to maintain the photon beamline positions put a significant constraint on the lattice design. Consequently the emittance of SPEAR3 is not on par with some of the recently-built third generation light sources. The present operational lattice has an emittance of 10 nm. For the photon beam brightness of SSRL to remain competitive among the new or upgraded ring-based light sources, it is necessary to significantly reduce the emittance of SPEAR3. In this paper we report our ongoing effort to develop a lower emittance solution for SSRL. We first show the potential of the SPEAR3 lattice with results of the standard cell study using the GLASS technique. This is followed by a discussion of the design strategy for full-ring linear lattices. Several lattice options are compared. We then show the methods and results for dynamic aperture optimization. Experiments were also conducted on the SPEAR3 ring to implement the lattice and to measure the key lattice parameters.

  15. Tuning the Magnetic Transport of an Induction LINAC using Emittance

    SciTech Connect

    Houck, T L; Brown, C G; Ong, M M; Paul, A C; Wargo, P E; Zentler, J M

    2006-08-11

    The Lawrence Livermore National Laboratory Flash X-Ray (FXR) machine is a linear induction accelerator used to produce a nominal 18 MeV, 3 kA, 65 ns pulse width electron beam for hydrodynamic radiographs. A common figure of merit for this type of radiographic machine is the x-ray dose divided by the spot area on the bremsstrahlung converter where a higher FOM is desired. Several characteristics of the beam affect the minimum attainable x-ray spot size. The most significant are emittance (chaotic transverse energy), chromatic aberration (energy variation), and beam motion (transverse instabilities and corkscrew motion). FXR is in the midst of a multi-year optimization project to reduce the spot size. This paper describes the effort to reduce beam emittance by adjusting the fields of the transport solenoids and position of the cathode. If the magnetic transport is not correct, the beam will be mismatched and undergo envelope oscillations increasing the emittance. We measure the divergence and radius of the beam in a drift section after the accelerator by imaging the optical transition radiation (OTR) and beam envelope on a foil. These measurements are used to determine an emittance. Relative changes in the emittance can be quickly estimated from the foil measurements allowing for an efficient, real-time study. Once an optimized transport field is determined, the final focus can be adjusted and the new x-ray spot measured. A description of the diagnostics and analysis is presented.

  16. Method of images applied to driven solid-state emitters

    NASA Astrophysics Data System (ADS)

    Scerri, Dale; Santana, Ted S.; Gerardot, Brian D.; Gauger, Erik M.

    2017-04-01

    Increasing the collection efficiency from solid-state emitters is an important step towards achieving robust single-photon sources, as well as optically connecting different nodes of quantum hardware. A metallic substrate may be the most basic method of improving the collection of photons from quantum dots, with predicted collection efficiency increases of up to 50%. The established "method-of-images" approach models the effects of a reflective surface for atomic and molecular emitters by replacing the metal surface with a second fictitious emitter which ensures appropriate electromagnetic boundary conditions. Here, we extend the approach to the case of driven solid-state emitters, where exciton-phonon interactions play a key role in determining the optical properties of the system. We derive an intuitive polaron master equation and demonstrate its agreement with the complementary half-sided cavity formulation of the same problem. Our extended image approach offers a straightforward route towards studying the dynamics of multiple solid-state emitters near a metallic surface.

  17. Electrical control of optical emitter relaxation pathways enabled by graphene

    NASA Astrophysics Data System (ADS)

    Tielrooij, K. J.; Orona, L.; Ferrier, A.; Badioli, M.; Navickaite, G.; Coop, S.; Nanot, S.; Kalinic, B.; Cesca, T.; Gaudreau, L.; Ma, Q.; Centeno, A.; Pesquera, A.; Zurutuza, A.; de Riedmatten, H.; Goldner, P.; García de Abajo, F. J.; Jarillo-Herrero, P.; Koppens, F. H. L.

    2015-03-01

    Controlling the energy flow processes and the associated energy relaxation rates of a light emitter is of fundamental interest and has many applications in the fields of quantum optics, photovoltaics, photodetection, biosensing and light emission. Advanced dielectric, semiconductor and metallic systems have been developed to tailor the interaction between an emitter and its environment. However, active control of the energy flow from an emitter into optical, electronic or plasmonic excitations has remained challenging. Here, we demonstrate in situ electrical control of the relaxation pathways of excited erbium ions, which emit light at the technologically relevant telecommunication wavelength of 1.5 μm. By placing the erbium at a few nanometres distance from graphene, we modify the relaxation rate by more than a factor of three, and control whether the emitter decays into electron-hole pairs, emitted photons or graphene near-infrared plasmons, confined to <15 nm from the graphene sheet. These capabilities to dictate optical energy transfer processes through electrical control of the local density of optical states constitute a new paradigm for active (quantum) photonics and can be applied using any combination of light emitters and two-dimensional materials.

  18. Process for making a cesiated diamond film field emitter and field emitter formed therefrom

    DOEpatents

    Anderson, D.F.; Kwan, S.W.

    1999-03-30

    A process for making a cesiated diamond film comprises (a) depositing a quantity of cesium iodide on the diamond film in a vacuum of between about 10{sup {minus}4} Torr and about 10{sup {minus}7} Torr, (b) increasing the vacuum to at least about 10{sup {minus}8} Torr, and (c) imposing an electron beam upon the diamond film, said electron beam having an energy sufficient to dissociate said cesium iodide and to incorporate cesium into interstices of the diamond film. The cesiated diamond film prepared according to the process has an operating voltage that is reduced by a factor of at least approximately 2.5 relative to conventional, non-cesiated diamond film field emitters. 2 figs.

  19. Process for making a cesiated diamond film field emitter and field emitter formed therefrom

    DOEpatents

    Anderson, David F.; Kwan, Simon W.

    1999-01-01

    A process for making a cesiated diamond film comprises (a) depositing a quantity of cesium iodide on the diamond film in a vacuum of between about 10.sup.-4 Torr and about 10.sup.-7 Torr, (b) increasing the vacuum to at least about 10.sup.-8 Torr, and (c) imposing an electron beam upon the diamond film, said electron beam having an energy sufficient to dissociate said cesium iodide and to incorporate cesium into interstices of the diamond film. The cesiated diamond film prepared according to the process has an operating voltage that is reduced by a factor of at least approximately 2.5 relative to conventional, non-cesiated diamond film field emitters.

  20. Proton Drip Line Nuclei from Z = 31 TO Z = 49 IN the Relativistic Hartree-Bogoliubov Model

    NASA Astrophysics Data System (ADS)

    Lalazissis, G. A.; Vretenar, D.; Ring, P.

    2001-11-01

    The structure of proton drip line nuclei in the 60 < A < 100 mass range is studied with the Relativistic Hartree Bogoliubov (RHB) model. For the elements which determine the astrophysical rapid proton capture process path, the RHB model predicts the location of the proton drip-line, the ground-state quadrupole deformations and one-proton separation energies at and beyond the drip-line. The results of the present theoretical investigation are compared with available experimental data. For possible odd-Z ground state proton emitters, the calculated deformed single-particle orbitals occupied by the odd valence proton and the corresponding spectroscopic factors are compared with predictions of the macroscopic-microscopic mass model.

  1. On the high intensity aspects of AGS Booster proton operation

    SciTech Connect

    Reece, R.K.; Ahrens, L.A.; Bleser, E.J.; Brennan, J.M.; Gardner, C.; Glenn, J.W.; Roser, T.; Shoji, Y.; van Asselt, W.; Weng, W.T.

    1993-06-01

    Observations of high intensity effects on the proton performance of the AGS Booster are presented, including present operational limits and correction methods. The transverse emittances, optimum tune working points, damping of coherent transverse oscillations and correction of stopband resonances through third-order are discussed in addition to the observed tune spread due to space charge forces. The initial longitudinal phase space distribution, capture and acceleration parameters and measurements are also given. Operational tools and strategies relevant to the high intensity setup are mentioned.

  2. On the high intensity aspects of AGS Booster proton operation

    SciTech Connect

    Reece, R.K.; Ahrens, L.A.; Bleser, E.J.; Brennan, J.M.; Gardner, C.; Glenn, J.W.; Roser, T.; Shoji, Y.; van Asselt, W.; Weng, W.T.

    1993-01-01

    Observations of high intensity effects on the proton performance of the AGS Booster are presented, including present operational limits and correction methods. The transverse emittances, optimum tune working points, damping of coherent transverse oscillations and correction of stopband resonances through third-order are discussed in addition to the observed tune spread due to space charge forces. The initial longitudinal phase space distribution, capture and acceleration parameters and measurements are also given. Operational tools and strategies relevant to the high intensity setup are mentioned.

  3. Analysis ob beam losses at PSR (Proton Storage Ring)

    SciTech Connect

    Macek, R.J.; Fitzgerald, D.H.; Hutson, R.L.; Plum, M.A.; Thiessen, H.A.

    1988-01-01

    Beam losses and the resulting component activation at the Los Alamos Proton Storage Ring (PSR) have limited operating currents to about 30..mu..A average at a repetition rate of 15 Hz. Loss rates were found to be approximately proportional to the circulating current and can be understood by a detailed accounting of emittance growth in the two step injection process along with Coulomb scattering of the stored beam during multiple traversals of the injection foil. Calculations and simulations of the losses are in reasonable agreement with measurements.

  4. Hafnia-plugged microcavities for thermal stability of selective emitters

    NASA Astrophysics Data System (ADS)

    Lee, Heon-Ju; Smyth, Katherine; Bathurst, Stephen; Chou, Jeffrey; Ghebrebrhan, Michael; Joannopoulos, John; Saka, Nannaji; Kim, Sang-Gook

    2013-06-01

    Two-dimensional arrays of micro-cavities effectively control photon motion and selectively emit radiation tailored to the preferred bandgap of photovoltaic (PV) cells, thus enhancing the efficiency of thermophotovoltaic energy conversion. At the high operating temperatures, however, the micro- and nano-patterned structures of the selective emitters quickly lose their integrity--obliterating the tight tolerances required for precise spectral control. Even if oxidation, recrystallization, and grain growth could be avoided with single-crystal tungsten (W) selective emitters with vacuum packaging, surface diffusion, evaporation, and re-condensation are not avoidable in long-term operation at high temperatures. The concept of a planar array of plugged micro-cavities to suppress the curvature-dependent thermal degradation modes is proposed and tested. Based on scale-accelerated failure tests of silicon devices, the lifetime of W selective emitters operating at 1100 K is estimated to be at least 30 yr.

  5. Lithium plasma emitter for collisionless magnetized plasma experiment.

    PubMed

    Kawamori, Eiichirou; Lee, Jyun-Yi; Huang, Yi-Jue; Syugu, Wun-Jheng; Song, Sung-Xuang; Hsieh, Tung-Yuan; Cheng, C Z

    2011-09-01

    This paper presents a newly developed lithium plasma emitter, which can provide quiescent and low-temperature collisionless conditions for magnetized plasma experiments. This plasma emitter generates thermal emissions of lithium ions and electrons to produce a lithium plasma. Lithium type beta-eucryptite and lanthanum-hexaboride (LaB(6)) powders were mixed and directly heated with a tungsten heater to synthesize ion and electron emissions. As a result, a plasma with a diameter of ~15 cm was obtained in a magnetic mirror configuration. The typical range of electron density was 10(12)-10(13) m(-3) and that of electron temperature was 0.1-0.8 eV with the emitter operation temperature of about 1500 K. The amplitude fluctuations for the plasma density were lower than 1%. © 2011 American Institute of Physics

  6. Physics and simulation of photonic crystal Purcell light emitters

    NASA Astrophysics Data System (ADS)

    Witzigmann, Bernd; Römer, Friedhard

    2008-02-01

    Photonic crystal membrane microcavities (PCMC) exhibit modes with highest quality factors and ultrasmall volume at the same time. This makes them the ideal solid state implementation for studying cavity quantum electrodynamics, as a quantum emitter such as a quantum dot can be placed at an electric field maximum with only moderate technological effort. Ultimately, this shall lead to novel classes of light emitters, such as highe efficiency LEDs or devices for quantum information processing. This paper discusses PCMC's operating in the weak coupling regime, shows an efficient and realistic simulation method based on the finite element method, and the design trade-offs for cavities used as light emitters. Finally, a comparison to measured spectra illustrates technological aspects.

  7. Gaseous Ultraviolet-Radiation Source with Electron Emitter

    NASA Astrophysics Data System (ADS)

    Hashiguchi, Seishiro; Tachibana, Kunihide

    2001-03-01

    An ultraviolet (UV) source is proposed. It resembles a dc-type plasma display panel (PDP) but the applied voltage is well below the breakdown voltage and an electron emitter is used. The advantage of the new UV source is that it can reduce energy dissipation due to creation of ions. Numerical calculations with pure xenon show an efficiency of 11% for the applied voltage of 210 V@. The emitter current of 1.3 mA/cm2 was needed to realize an UV-radiation energy equal to that of a conventional PDP@. The efficiency increased with decreasing applied voltage while the emitter current increased to obtain the same amount of UV-radiation energy.

  8. Spring structure for a thermionic converter emitter support arrangement

    DOEpatents

    Allen, D.T.

    1992-03-17

    A support is provided for use in a thermionic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end is supported by a spring structure that includes a pair of Belleville springs, and the spring structure is supported by a support structure fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element at the front end, a larger metal main support at the rear end that is attached to the housing, and with a ceramic layer between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer captured between the Belleville springs. 7 figs.

  9. Fully tuneable, Purcell-enhanced solid-state quantum emitters

    SciTech Connect

    Petruzzella, M. Xia, T.; Pagliano, F.; Birindelli, S.; Zobenica, Z.; Fiore, A.; Midolo, L.; Li, L. H.; Linfield, E. H.

    2015-10-05

    We report the full energy control over a semiconductor cavity-emitter system, consisting of single Stark-tunable quantum dots embedded in mechanically reconfigurable photonic crystal membranes. A reversible wavelength tuning of the emitter over 7.5 nm as well as an 8.5 nm mode shift are realized on the same device. Harnessing these two electrical tuning mechanisms, a single exciton transition is brought on resonance with the cavity mode at several wavelengths, demonstrating a ten-fold enhancement of its spontaneous emission. These results open the way to bring several cavity-enhanced emitters mutually into resonance and therefore represent a key step towards scalable quantum photonic circuits featuring multiple sources of indistinguishable single photons.

  10. Low Emittance Tuning Studies for SuperB

    SciTech Connect

    Liuzzo, Simone; Biagini, Maria; Raimondi, Pantaleo; Donald, Martin; /SLAC

    2012-07-06

    SuperB[1] is an international project for an asymmetric 2 rings collider at the B mesons cm energy to be built in the Rome area in Italy. The two rings will have very small beam sizes at the Interaction Point and very small emittances, similar to the Linear Collider Damping Rings ones. In particular, the ultra low vertical emittances, 7 pm in the LER and 4 pm in the HER, need a careful study of the misalignment errors effects on the machine performances. Studies on the closed orbit, vertical dispersion and coupling corrections have been carried out in order to specify the maximum allowed errors and to provide a procedure for emittance tuning. A new tool which combines MADX and Matlab routines has been developed, allowing for both corrections and tuning. Results of these studies are presented.

  11. High efficiency and stable white OLED using a single emitter

    SciTech Connect

    Li, Jian

    2016-01-18

    The ultimate objective of this project was to demonstrate an efficient and stable white OLED using a single emitter on a planar glass substrate. The focus of the project is on the development of efficient and stable square planar phosphorescent emitters and evaluation of such class of materials in the device settings. Key challenges included improving the emission efficiency of molecular dopants and excimers, controlling emission color of emitters and their excimers, and improving optical and electrical stability of emissive dopants. At the end of this research program, the PI has made enough progress to demonstrate the potential of excimer-based white OLED as a cost-effective solution for WOLED panel in the solid state lighting applications.

  12. Biological treatment of clogged emitters in a drip irrigation system.

    PubMed

    Sahin, Ustün; Anapali, Omer; Dönmez, Mesude Figen; Sahin, Fikrettin

    2005-09-01

    This study was conducted to investigate microbial organisms that can be used for preventing clogging in drip irrigation systems caused by biological factors. A total of 25 fungi isolate and 121 bacterial strains were isolated from water samples collected from drip irrigation systems in tomato greenhouses in the eastern Anatolia region of Turkey in the spring season of 2001. Biological clogging of emitters in a model drip irrigation system was experimentally caused by application of the microorganisms (fungi and bacteria) isolated in the study. Three antagonistic bacterial strains in the genus Bacillus spp (ERZ, OSU-142) and Burkholdria spp (OSU-7) were used for treatment of biological clogging of the emitters. The results showed that the antagonistic bacterial strains tested have the potential to be used as anti-clogging agents for treatment of emitters in drip irrigation system. This is the first study that demonstrated that antagonistic microorganisms can be utilized for treatment of clogging in drip irrigation systems.

  13. Field Emission from Lateral Multiwalled Carbon Nanotube Yarn Emitters

    NASA Astrophysics Data System (ADS)

    Chen, Guohai; Song, Yenan

    2016-10-01

    A field emission from a lateral emitter made by a multiwalled carbon nanotube (MWCNT) yarn was investigated. The lateral emitter showed an excellent field emission performance with a low turn-on electric field of 1.13 V/um at an emission current of 1 uA, high emission current of 0.2 mA at an applied voltage of 700 V, and long-time emission stability for over 20 h without any significant current decay under an initial emission current of about 0.10 mA. The lateral emitter also demonstrated a uniform line emission pattern. It is suggested that the field emission occurs from the outmost MWCNTs which are protruding out from the yarn surface.

  14. Study of narrowband single photon emitters in polycrystalline diamond films

    SciTech Connect

    Sandstrom, Russell G.; Shimoni, Olga; Martin, Aiden A.; Aharonovich, Igor

    2014-11-03

    Quantum information processing and integrated nanophotonics require robust generation of single photon emitters on demand. In this work, we demonstrate that diamond films grown on a silicon substrate by microwave plasma chemical vapor deposition can host bright, narrowband single photon emitters in the visible—near infra-red spectral range. The emitters possess fast lifetime (∼several ns), absolute photostability, and exhibit full polarization at excitation and emission. Pulsed and continuous laser excitations confirm their quantum behaviour at room temperature, while low temperature spectroscopy is performed to investigate inhomogeneous broadening. Our results advance the knowledge of solid state single photon sources and open pathways for their practical implementation in quantum communication and quantum information processing.

  15. Spring structure for a thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T.

    1992-01-01

    A support is provided for use in a thermionic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  16. HIGH RESOLUTION EMITTANCE MEASUREMENTS AT SNS FRONT END

    SciTech Connect

    Aleksandrov, Alexander V; Zhukov, Alexander P

    2013-01-01

    The Spallation Neutron Source (SNS) linac accelerates an H- beam from 2.5MeV up to 1GeV. Recently the emittance scanner in the MEBT (2.5 MeV) was upgraded. In addition to the slit - harp measurement, we now can use a slit installed on the same actuator as the harp. In combination with a faraday cup located downstream in DTL part of the linac, it represents a classical slit-slit emittance measurement device. While a slit slit scan takes much longer, it is immune to harp related problems such as wire cross talk, and thus looks promising for accurate halo measurements. Time resolution of the new device seems to be sufficient to estimate the amount of beam in the chopper gap (the scanner is downstream of the chopper), and probably to measure its emittance. This paper describes the initial measurements with the new device and some model validation data.

  17. Intra-beam scattering studies for low emittance at BAPS

    NASA Astrophysics Data System (ADS)

    Tian, Sai-Ke; Wang, Jiu-Qing; Xu, Gang; Jiao, Yi

    2015-06-01

    The target parameters of modern ultra-low emittance storage ring light sources are entering into a regime where intra-beam scattering (IBS) becomes important and, in the case of the Beijing Advanced Photon Source (BAPS), which is being designed at the Institute of High Energy Physics (IHEP), even a limitation for achieving the desired emittances in both transverse planes at the diffraction limit for X-ray wavelengths (≈10 pm). Due to the low emittance, the IBS effect will be very strong. Accurate calculations are needed to check if the design goal (ɛh+ɛv = 20 pm) can be reached. In this paper, we present the results of numerical simulation studies of the IBS effect on a BAPS temporary design lattice.

  18. Emittance growth in the DARHT Axis-II Downstream Transport

    SciTech Connect

    Ekdahl, Jr., Carl August; Schulze, Martin E.

    2015-04-14

    Using a particle-in-cell (PIC) code, we investigated the possibilities for emittance growth through the quadrupole magnets of the system used to transport the high-current electron beam from an induction accelerator to the bremsstrahlung converter target used for flash radiography. We found that even highly mismatched beams exhibited little emittance growth (< 6%), which we attribute to softening of their initial hard edge current distributions. We also used this PIC code to evaluate the accuracy of emittance measurements using a solenoid focal scan following the quadrupole magnets. If the beam is round after the solenoids, the simulations indicate that the measurement is highly accurate, but it is substantially inaccurate for elliptical beams

  19. SiC IR emitter design for thermophotovoltaic generators

    NASA Astrophysics Data System (ADS)

    Fraas, Lewis M.; Ferguson, Luke; McCoy, Larry G.; Pernisz, Udo C.

    1996-02-01

    An improved ceramic spine disc burner/emitter for use in a thermophotovoltaic (TPV) generator is described. A columnar infrared (IR) emitter consisting of a stack of silicon carbide (SiC) spine discs provides for both high conductance for the combustion gases and efficient heat transfer from the hot combustion gases to the emitter. Herein, we describe the design, fabrication, and testing of this SiC burner as well as the characterization of the IR spectrum it emits. We note that when the SiC column is surrounded with fused silica heat shields, these heat shields suppress the emitted power beyond 4 microns. Thus, a TPV generator using GaSb photovoltaic cells covered by simple dielectric filters can convert over 30% of the emitted IR radiation to DC electric power.

  20. The proton collecting function of the inner surface of cytochrome c oxidase from Rhodobacter sphaeroides.

    PubMed

    Marantz, Y; Nachliel, E; Aagaard, A; Brzezinski, P; Gutman, M

    1998-07-21

    The experiments presented in this study address the problem of how the cytoplasmic surface (proton-input side) of cytochrome c oxidase interacts with protons in the bulk. For this purpose, the cytoplasmic surface of the enzyme was labeled with a fluorescein (Flu) molecule covalently bound to Cys223 of subunit III. Using the Flu as a proton-sensitive marker on the surface and phiOH as a soluble excited-state proton emitter, the dynamics of the acid-base equilibration between the surface and the bulk was measured in the time-resolved domain. The results were analyzed by using a rigorous kinetic analysis that is based on numeric integration of coupled nonliner differential rate equations in which the rate constants are used as adjustable parameters. The analysis of 11 independent measurements, carried out under various initial conditions, indicated that the protonation of the Flu proceeds through multiple pathways involving diffusion-controlled reactions and proton exchange among surface groups. The surface of the protein carries an efficient system made of carboxylate and histidine moieties that are sufficiently close to each other as to form a proton-collecting antenna. It is the passage of protons among these sites that endows cytochrome c oxidase with the capacity to pick up protons from the buffered cytoplasmic matrix within a time frame compatible with the physiological turnover of the enzyme.

  1. Spectrum of classes of point emitters of electromagnetic wave fields.

    PubMed

    Castañeda, Román

    2016-09-01

    The spectrum of classes of point emitters has been introduced as a numerical tool suitable for the design, analysis, and synthesis of non-paraxial optical fields in arbitrary states of spatial coherence. In this paper, the polarization state of planar electromagnetic wave fields is included in the spectrum of classes, thus increasing its modeling capabilities. In this context, optical processing is realized as a filtering on the spectrum of classes of point emitters, performed by the complex degree of spatial coherence and the two-point correlation of polarization, which could be implemented dynamically by using programmable optical devices.

  2. Observation of negative differential transconductance in tunneling emitter bipolar transistors

    NASA Astrophysics Data System (ADS)

    van Veenhuizen, Marc J.; Locatelli, Nicolas; Moodera, Jagadeesh; Chang, Joonyeon

    2009-08-01

    We report on measurement of negative differential transconductance (NDTC) of iron (Fe)/magnesium-oxide (MgO)/silicon tunneling emitter NPN bipolar transistors. Device simulations reveal that the NDTC is a consequence of an inversion layer at the tunneling-oxide/P-silicon interface for low base voltages. Electrons travel laterally through the inversion layer into the base and give rise to an increase in collector current. The NDTC results from the recombination of those electrons at the interface between emitter and base contact which is dependent on the base voltage. For larger base voltages, the inversion layer disappears marking the onset of normal bipolar transistor behavior.

  3. Back-contacted emitter GaAs solar cells

    SciTech Connect

    Araujo, G.L.; Marti, A.; Algora, C. )

    1990-06-25

    A new device structure to improve the performance of concentrator GaAs solar cells is described and the first experimental results are reported. The reason for such an improvement relies on a drastic reduction of the shadowing and series resistance losses based on the possibility of back contacting the emitter region of the solar cell. The experimental results obtained with devices of these types, with a simplified structure, fabricated by liquid phase epitaxy, demonstrate the feasibility and correct operation of the proposed back contact of the emitter of the cells.

  4. LOW EMITTANCE ELECTRON BEAMS FOR THE RHIC ELECTRON COOLER

    SciTech Connect

    KEWISCH,J.; CHANG, X.

    2007-06-25

    An electron cooler, based on an Energy Recovery Linac (ERL) is under development for the Relativistic Heavy Ion Collider (RMIC) at Brookhaven National Laboratory. This will be the first electron cooler operating at high energy with bunched beams. In order to achieve sufficient cooling of the ion beams the electron have to have a charge of 5 nC and a normalized emittance less than 4 {mu}. This paper presents the progress in optimizing the injector and the emittance improvements from shaping the charge distribution in the bunch.

  5. Pyrometric method for measuring emittances at high temperatures

    NASA Astrophysics Data System (ADS)

    Ballestrín, J.; Rodríguez, J.; Carra, M. E.; Cañadas, I.; Roldan, M. I.; Barbero, J.; Marzo, A.

    2016-05-01

    In this work an alternative method for emittance determination based on pyrometric measurements is presented. The measurement procedure has been applied to AISI 310S steel samples in the Plataforma Solar de Almería vertical axis solar furnace SF5. The experimental results show that emittance increases with increasing temperature and decreases with increasing wavelength. This behaviour is in agreement with experimental results obtained by other authors. Analysis of tests has revealed a good repeatability (1%) and accuracy (< 2%) of this measurement procedure.

  6. Distributed proximity sensor system having embedded light emitters and detectors

    NASA Technical Reports Server (NTRS)

    Lee, Sukhan (Inventor)

    1990-01-01

    A distributed proximity sensor system is provided with multiple photosensitive devices and light emitters embedded on the surface of a robot hand or other moving member in a geometric pattern. By distributing sensors and emitters capable of detecting distances and angles to points on the surface of an object from known points in the geometric pattern, information is obtained for achieving noncontacting shape and distance perception, i.e., for automatic determination of the object's shape, direction and distance, as well as the orientation of the object relative to the robot hand or other moving member.

  7. Excellent oxidation endurance of boron nitride nanotube field electron emitters

    SciTech Connect

    Song, Yenan; Song, Yoon-Ho; Milne, William I.; Jin Lee, Cheol

    2014-04-21

    Boron nitride nanotubes (BNNTs) are considered as a promising cold electron emission material owing to their negative electron affinity. BNNT field emitters show excellent oxidation endurance after high temperature thermal annealing of 600 °C in air ambient. There is no damage to the BNNTs after thermal annealing at a temperature of 600 °C and also no degradation of field emission properties. The thermally annealed BNNTs exhibit a high maximum emission current density of 8.39 mA/cm{sup 2} and show very robust emission stability. The BNNTs can be a promising emitter material for field emission devices under harsh oxygen environments.

  8. Thermal emittance and response time of a cesium antimonide photocathode

    NASA Astrophysics Data System (ADS)

    Cultrera, Luca; Bazarov, Ivan; Bartnik, Adam; Dunham, Bruce; Karkare, Siddharth; Merluzzi, Richard; Nichols, Matthew

    2011-10-01

    Measurements of the intrinsic emittance and response time of a Cs3Sb photocathode are presented. The emittance is obtained with a solenoid scan technique using a high voltage dc photoemission gun. Photoemission response time is evaluated using a RF deflecting cavity synchronized to a picosecond laser pulse train. We find that Cs3Sb has both small mean transverse energy, 160 ± 10 meV at 532 nm laser wavelength, and a prompt response time (below the resolution of our measurement) making it a suitable material for high brightness electron photoinjectors.

  9. Emittance Measurements at the Langley Chemical Physics Laboratory

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.

    1960-01-01

    Total hemispherical emittance measurements are made routinely for materials which may be heated by electrical resistance methods over the temperature range of 600 degrees to 2,000 F by using a black-body reference method. This employs a conical black body and a thermopile detector with a calcium fluoride lens. Emittance is obtained by measuring the radiant flux from the specimen strip and comparing it with the flux from an equal area of the black-body cone at the same temperature. The temperature measurements are made by use of thermocouples. It is planned to extend the temperature range of this type of measurement to temperatures above 2,000 F. Another technique has been investigated for measuring emittance of materials not amenable to electrical heating or thermocouple attachment. This method uses a black-body-cavity furnace similar to that used in reference 5 to measure emittance of transparent materials such as glass. The method employs a heated black-body cavity in which the semicircular specimen is allowed to come to the equilibrium temperature of the cavity and then is rotated in front of a water-cooled viewing port where a sensitive thermistor detector alternately views the specimen surface and the black-body cavity. The ratio of the two readings gives the specimen emittance directly, for the temperature of the black body. The detector output is recorded on a fast Brown self-balancing potentiometer. The furnace is provided with a water-cooled blackened shutter which may be inserted behind the specimen to eliminate any transmitted black-body radiation if the specimen is transparent. This apparatus is capable of measuring total normal emittance over the temperature range of 1,000 degrees to 2,000 F. Preliminary data for boron nitride specimens of two thicknesses are shown where total normal emittance is plotted against temperature for two experimental conditions: (1) black-body radiation incident on the back of the specimen and (2) no black-body radiation

  10. Improved brightness on broad-area single emitter (BASE) modules

    NASA Astrophysics Data System (ADS)

    Pawlik, Susanne; Guarino, Andrea; Matuschek, Nicolai; Bättig, Rainer; Arlt, Sebastian; Lu, Denis; Zayer, Nadhum; Greatrex, Jeffery; Sverdlov, Boris; Valk, Bernd; Lichtenstein, Norbert

    2009-02-01

    In this communication we report on the approaches to increase the brightness of Bookham's latest generations of high power pump modules. Since the single-emitter laser diode is the essential building block in all module designs, the optimization of the device design towards higher wall-plug efficiency, higher brightness and better reliability is one focus of the ongoing development efforts at Bookham. By using an analytical simulation tool critical parameters for efficient emitter-fiber coupling as the beam divergence and coupling scheme could be identified.

  11. Uncorrelated Energy Spread and Longitudinal Emittance of a Photoinjector Beam

    SciTech Connect

    Huang, Z; Dowell, D.; Emma, P.; Limborg-Deprey, C.; Stupakov, G.; Wu, J.; /SLAC

    2005-05-25

    Longitudinal phase space properties of a photoinjector beam are important in many areas of high-brightness beam applications such as bunch compression, transverse-to-longitudinal emittance exchange, and high-gain free-electron lasers. In this paper, we discuss both the rf and the space charge contributions to the uncorrelated energy spread of the beam generated from a laser-driven rf gun. We compare analytical expressions for the uncorrelated energy spread and the longitudinal emittance with numerical simulations and recent experimental results.

  12. The physics of Cerenkov light production during proton therapy.

    PubMed

    Helo, Y; Kacperek, A; Rosenberg, I; Royle, G; Gibson, A P

    2014-12-07

    There is increasing interest in using Cerenkov emissions for quality assurance and in vivo dosimetry in photon and electron therapy. Here, we investigate the production of Cerenkov light during proton therapy and its potential applications in proton therapy. A primary proton beam does not have sufficient energy to generate Cerenkov emissions directly, but we have demonstrated two mechanisms by which such emissions may occur indirectly: (1) a fast component from fast electrons liberated by prompt gamma (99.13%) and neutron (0.87%) emission; and (2) a slow component from the decay of radioactive positron emitters. The fast component is linear with dose and doserate but carries little spatial information; the slow component is non-linear but may be localised. The properties of the two types of emission are explored using Monte Carlo modelling in GEANT4 with some experimental verification. We propose that Cerenkov emissions could contribute to the visual sensation reported by some patients undergoing proton therapy of the eye and we discuss the feasibility of some potential applications of Cerenkov imaging in proton therapy.

  13. RHIC polarized proton-proton operation at 100 GeV in Run 15

    SciTech Connect

    Schoefer, V.; Aschenauer, E. C.; Atoian, G.; Blaskiewicz, M.; Brown, K. A.; Bruno, D.; Connolly, R.; D Ottavio, T.; Drees, K. A.; Dutheil, Y.; Fischer, W.; Gardner, C.; Gu, X.; Hayes, T.; Huang, H.; Laster, J.; Liu, C.; Luo, Y.; Makdisi, Y.; Marr, G.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R.; Marusic, A.; Minty, M.; Montag, C.; Morris, J.; Narayan, G.; Nemesure, S.; Pile, P.; Poblaguev, A.; Ranjbar, V.; Robert-Demolaize, G.; Roser, T.; Schmidke, W. B.; Severino, F.; Shrey, T.; Smith, K.; Steski, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; White, S.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S. Y.

    2015-05-03

    The first part of RHIC Run 15 consisted of ten weeks of polarized proton on proton collisions at a beam energy of 100 GeV at two interaction points. In this paper we discuss several of the upgrades to the collider complex that allowed for improved performance. The largest effort consisted in commissioning of the electron lenses, one in each ring, which are designed to compensate one of the two beam-beam interactions experienced by the proton bunches. The e-lenses raise the per bunch intensity at which luminosity becomes beam-beam limited. A new lattice was designed to create the phase advances necessary for a beam-beam compensation with the e-lens, which also has an improved off-momentum dynamic aperture relative to previous runs. In order to take advantage of the new, higher intensity limit without suffering intensity driven emittance deterioration, other features were commissioned including a continuous transverse bunch-by-bunch damper in RHIC and a double harmonic RF cature scheme in the Booster. Other high intensity protections include improvements to the abort system and the installation of masks to intercept beam lost due to abort kicker pre-fires.

  14. Proton Remains Puzzling

    SciTech Connect

    Gao, Haiyan; Liu, Tianbo; Peng, Chao; Ye, Zhihong; Zhao, Zhiwen

    2015-01-01

    Nucleons are building blocks of visible matter, and are responsible for more than 99% of the visible mass in the universe despite the fact that the discovery of the Higgs boson is almost irrelevant to the origin of the proton mass. While major progress has been made in the last two decades in understanding the proton spin puzzle discovered in the late 1980s by the European Muon Collaboration, a new proton puzzle emerged in the last several years concerning the proton charge radius, which is the charge weighted size of the proton. In this paper we will review the latest situation concerning the proton charge radius, mass and spin, and discuss upcoming new experiments addressing these puzzles, as well as implications for new physics.

  15. The effects of emitter-tied field plates on lateral PNP ionizing radiation response

    SciTech Connect

    Barnaby, H.J.; Schrimpf, R.D.; Cirba, C.R.; Pease, R.L.; Fleetwood, D.M.; Kosier, S.L.

    1998-03-01

    Radiation response comparisons of lateral PNP bipolar technologies reveal that device hardening may be achieved by extending the emitter contact over the active base. The emitter-tied field plate suppresses recombination of carriers with interface traps.

  16. Development of a pepper-pot emittance meter for diagnostics of low-energy multiply charged heavy ion beams extracted from an ECR ion source

    SciTech Connect

    Nagatomo, T. Kase, M.; Kamigaito, O.; Nakagawa, T.; Tzoganis, V.

    2016-02-15

    Several fluorescent materials were tested for use in the imaging screen of a pepper-pot emittance meter that is suitable for investigating the beam dynamics of multiply charged heavy ions extracted from an ECR ion source. SiO{sub 2} (quartz), KBr, Eu-doped CaF{sub 2}, and Tl-doped CsI crystals were first irradiated with 6.52-keV protons to determine the effects of radiation damage on their fluorescence emission properties. For such a low-energy proton beam, only the quartz was found to be a suitable fluorescent material, since the other materials suffered a decay in fluorescence intensity with irradiation time. Subsequently, quartz was irradiated with heavy {sup 12}C{sup 4+}, {sup 16}O{sup 4+}, and {sup 40}Ar{sup 11+} ions, but it was found that the fluorescence intensity decreased too rapidly to measure the emittance of these heavy-ion beams. These results suggest that a different energy loss mechanism occurs for heavier ions and for protons.

  17. Development of a pepper-pot emittance meter for diagnostics of low-energy multiply charged heavy ion beams extracted from an ECR ion source.

    PubMed

    Nagatomo, T; Tzoganis, V; Kase, M; Kamigaito, O; Nakagawa, T

    2016-02-01

    Several fluorescent materials were tested for use in the imaging screen of a pepper-pot emittance meter that is suitable for investigating the beam dynamics of multiply charged heavy ions extracted from an ECR ion source. SiO2 (quartz), KBr, Eu-doped CaF2, and Tl-doped CsI crystals were first irradiated with 6.52-keV protons to determine the effects of radiation damage on their fluorescence emission properties. For such a low-energy proton beam, only the quartz was found to be a suitable fluorescent material, since the other materials suffered a decay in fluorescence intensity with irradiation time. Subsequently, quartz was irradiated with heavy (12)C(4+), (16)O(4+), and (40)Ar(11+) ions, but it was found that the fluorescence intensity decreased too rapidly to measure the emittance of these heavy-ion beams. These results suggest that a different energy loss mechanism occurs for heavier ions and for protons.

  18. Bias dependence of synergistic radiation effects induced by electrons and protons on silicon bipolar junction transistors

    NASA Astrophysics Data System (ADS)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Ma, Guoliang; Xiao, Liyi

    2015-06-01

    Bias dependence on synergistic radiation effects caused by 110 keV electrons and 170 keV protons on the current gain of 3DG130 NPN bipolar junction transistors (BJTs) is studied in this paper. Experimental results indicate that the influence induced by 170 keV protons is always enhancement effect during the sequential irradiation. However, the influence induced by 110 keV electrons on the BJT under various bias cases is different during the sequential irradiation. The transition fluence of 110 keV electrons is dependent on the bias case on the emitter-base junction of BJT.

  19. Nonlocal effects: relevance for the spontaneous emission rates of quantum emitters coupled to plasmonic structures.

    PubMed

    Filter, Robert; Bösel, Christoph; Toscano, Giuseppe; Lederer, Falk; Rockstuhl, Carsten

    2014-11-01

    The spontaneous emission rate of dipole emitters close to plasmonic dimers are theoretically studied within a nonlocal hydrodynamic model. A nonlocal model has to be used since quantum emitters in the immediate environment of a metallic nanoparticle probe its electronic structure. Compared to local calculations, the emission rate is significantly reduced. The influence is mostly pronounced if the emitter is located close to sharp edges. We suggest to use quantum emitters to test nonlocal effects in experimentally feasible configurations.

  20. Beta Decay of the Proton-Rich Nuclei 102Sn and 104Sn

    SciTech Connect

    Karny, M.; Batist, L.; Banu, A.; Becker, F.; Blazhev, A.; Brown, B. A.; Bruchle, W.; Doring, J.; Faestermann, T.; Gorska, M.; Grawe, H.; Janas, Z.; Jungclaus, A.; Kavatsyuk, M.; Kavatsyuk, O.; Kirchner, R.; La Commara, M.; Mandal, S.; Mazzocchi, C.; Miernik, K.; Mukha, I.; Muralithar, S.; Plettner, C.; Plochocki, A.; Roeckl, E.; Romoli, M.; Rykaczewski, Krzysztof Piotr; Schadel, M.; Schmidt, K.; Schwengner, R.; Zylicz, J.

    2006-01-01

    The {beta} decays of {sup 102}Sn and {sup 104}Sn were studied by using high-resolution germanium detectors as well as a Total Absorption Spectrometer (TAS). For {sup 104}Sn, with three new {beta}-delayed {gamma}-rays identified, the total Gamow-Teller strength (BGT) value of 2.7(3) was obtained. For {sup 102}Sn, the {gamma}-{gamma} coincidence data were collected for the first time, allowing us to considerably extend the decay scheme. This scheme was used to unfold the TAS data and to deduce a BGT value of 4.2(8) for this decay. This result is compared to shell model predictions, yielding a hindrance factor of 3.6(7) in agreement with those obtained previously for {sup 98}Cd and {sup 100}In. Together with the latter two, {sup 102}Sn completes the triplet of Z {le} 50, N {ge} 50 nuclei with two proton holes, one proton hole and one neutron particle, and two neutron particles with respect to the doubly magic {sup 100}Sn core.

  1. Strong Coupling of Single Emitters to Surface Plasmons

    DTIC Science & Technology

    2007-07-01

    individual optical emitters and elec- tromagnetic excitations in conducting nanostructures. The excitations are optical plasmons that can be local- ized to...subwavelength dimensions. Under realistic conditions, the tight confinement causes optical emission to be almost entirely directed into the propagating...has been substantial interest in nanoscale optical devices based on the electromagnetic sur- face modes surface plasmons associated with subwave

  2. On the equivalent dose for Auger electron emitters.

    PubMed

    Howell, R W; Narra, V R; Sastry, K S; Rao, D V

    1993-04-01

    Radionuclides that emit Auger electrons are widely used in nuclear medicine (e.g., 99mTc, 123I, 201Tl) and biomedical research (e.g., 51Cr, 125I), and they are present in the environment (e.g., 40K, 55Fe). Depending on the subcellular distribution of the radionuclide, the biological effects caused by tissue-incorporated Auger emitters can be as severe as those from high-LET alpha particles. However, the recently adopted recommendations of the International Commission on Radiological Protection (ICRP) provide no guidance with regard to calculating the equivalent dose for these radionuclides. The present work, using spermatogenesis in mouse testis as the experimental model, shows that the lethality of the prolific Auger emitter 125I is linearly dependent on the fraction of the radioactivity in the organ that is bound to DNA. This suggests that the equivalent dose for Auger emitters may have a similar linear dependence. Accordingly, a formalism for calculating the equivalent dose for Auger emitters is advanced within the ICRP framework.

  3. Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

    SciTech Connect

    Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi

    2008-08-22

    Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

  4. Transverse beam emittance measurement using quadrupole variation at KIRAMS-430

    NASA Astrophysics Data System (ADS)

    An, Dong Hyun; Hahn, Garam; Park, Chawon

    2015-02-01

    In order to produce a 430 MeV/u carbon ion (12 C 6+) beam for medical therapy, the Korea Institute of Radiological & Medical Sciences (KIRAMS) has carried out the development of a superconducting isochronous cyclotron, the KIRAMS-430. At the extraction of the cyclotron, an Energy Selection System (ESS) is located to modulate the fixed beam energy and to drive the ion beam through High Energy Beam Transport (HEBT) into the treatment room. The beam emittance at the ion beamline is to be measured to provide information on designing a beam with high quality. The well-known quadrupole variation method was used to determine the feasibility of measuring the transverse beam emittance. The beam size measured at the beam profile monitor (BPM) is to be utilized and the transformation of beam by transfer matrix is to be applied being taken under various transport condition of varying quadrupole magnetic strength. Two different methods where beam optics are based on the linear matrix formalism and particle tracking with a 3-D magnetic field distribution obtained by using OPERA3D TOSCA, are applied to transport the beam. The fittings for the transformation parameters are used to estimate the transverse emittance and the twiss parameters at the entrance of the quadrupole in the ESS. Including several systematic studies, we conclude that within the uncertainty the estimated emittances are consistent with the ones calculated by using Monte Carlo simulations.

  5. High-absorptance high-emittance anodic coating

    NASA Technical Reports Server (NTRS)

    Le, Huong Giang (Inventor); Chesterfield, John L. (Inventor)

    1998-01-01

    A colored anodic coating for use on surfaces of substrates, e.g. aluminum substrates in which it is desirable to maintain a high solar absorptance (a) and a high infrared emittance (e), particularly in low earth orbit space environments. This anodic coating is preferably a dark colored coating, and even more preferably a black coating. This coating allows a touch temperature within an acceptable design range to preclude burning of an astronaut in case of contact, but also allows a solar radiation absorption in an amount such that an a/e ratio of unity is achieved. The coating of the invention comprises a first layer in the form of an acid anodized colored anodic layer for achieving a high solar absorptance and a second or high emittance layer in the form of a clear acid anodized layer for achieving a high emittance. The entire coating is quite thin, e.g. 1-2 mils and is quite stable in a hostile space environment of the type encountered in a low earth orbit. The coating is obtained by first creating the high emittance clear anodized coating on the metal surface followed by anodizing using a colored anodizing process.

  6. Achieving ultra-high temperatures with a resistive emitter array

    NASA Astrophysics Data System (ADS)

    Danielson, Tom; Franks, Greg; Holmes, Nicholas; LaVeigne, Joe; Matis, Greg; McHugh, Steve; Norton, Dennis; Vengel, Tony; Lannon, John; Goodwin, Scott

    2016-05-01

    The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community to also develop larger-format infrared emitter arrays to support the testing of systems incorporating these detectors. In addition to larger formats, many scene projector users require much higher simulated temperatures than can be generated with current technology in order to fully evaluate the performance of their systems and associated processing algorithms. Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a new infrared scene projector architecture capable of producing both very large format (>1024 x 1024) resistive emitter arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During earlier phases of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1400 K. New emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures. Test results from pixels fabricated using the new material set will be presented and discussed. A 'scalable' Read In Integrated Circuit (RIIC) is also being developed under the same UHT program to drive the high temperature pixels. This RIIC will utilize through-silicon via (TSV) and Quilt Packaging (QP) technologies to allow seamless tiling of multiple chips to fabricate very large arrays, and thus overcome the yield limitations inherent in large-scale integrated circuits. Results of design verification testing of the completed RIIC will be presented and discussed.

  7. What Exactly Is the Light Emitter of a Firefly?

    PubMed

    Cheng, Yuan-Yuan; Liu, Ya-Jun

    2015-11-10

    Firefly bioluminescence attracts people by its glaring beauty and fascinating applications, but what is the light emitter of a firefly? The answer to this question has been explored since before the 1960s. The unanimously accepted answer is that excited-state oxyluciferin is the light emitter. The complexity of this question arises from the existence of six chemical forms (keto, enol, keto-1, enol-1, enol-1′, and enol-2) of oxyluciferin. After decades of experimental and theoretical efforts, a consistent conclusion was almost reached in 2011: excited-state keto-1 is the only light emitter in fireflies. However, the debate is raised again by the latest in vitro experimental results. This study will solve this contradiction via hybrid quantum mechanics and molecular mechanics (QM/MM) calculations combined with molecular dynamics (MD). The calculations were performed in the real protein for the six chemical forms of oxyluciferin and their corresponding analogues employed in the latest experiments. By considering the real environment, the pH value, and a possible equilibrium of the chemical forms of oxyluciferin in vivo, the calculated results indicate that the main emitter is still the excited-state keto-1 form.

  8. Low emittance injector design for free electron lasers

    NASA Astrophysics Data System (ADS)

    Bettoni, S.; Pedrozzi, M.; Reiche, S.

    2015-12-01

    Several parameters determine the performance of free electron lasers: the slice and the projected emittance, the slice energy spread, and the peak current are the most crucial ones. The peak current is essentially obtained by magnetic compression stages along the machine or occasionally assisted by velocity bunching at low energy. The minimum emittance and the alignment of the slices along the bunch are mainly determined in the low energy part of the accelerator (injector). Variations at the per-mille level of several parameters in this section of the machine strongly influence these quantities with highly nonlinear dynamic. We developed a numerical tool to perform the optimization of the injector. We applied this code to optimize the SwissFEL injector, assuming different gun designs, initial bunch lengths and intrinsic emittances. We obtained an emittance along the bunch of 0.14 mm mrad and around 0.08 mm mrad for the maximum and the minimum SwissFEL charges (200 and 10 pC, respectively). We applied the same tool to a running injector, where we automatized the optimization of the machine.

  9. Selective solar absorber emittance measurement at elevated temperature

    NASA Astrophysics Data System (ADS)

    Giraud, Philémon; Braillon, Julien; Raccurt, Olivier

    2017-06-01

    Durability of solar components for CSP (Concentrated Solar Power Plant) technologies is a key point to lower cost and ensure their large deployment. These technologies concentrated the solar radiation by means of mirrors on a receiver tube where it is collected as thermal energy. The absorbers are submitted to strong environmental constraints and the degradation of their optical properties (emittance and solar absorbance) have a direct impact on performance. The characterization of a material in such condition is complicated and requires advanced apparatuses, and different measurement methods exist for the determination of the two quantities of relevance regarding an absorber, which are its emittance and its solar absorbance. The objective is to develop new optical equipment for measure the emittance of this solar absorber at elevated temperature. In this paper, we present an optical bench developed for emittance measurement on absorbers is conditions of use. Results will be shown, with a discussion of some factors of influence over this measurement and how to control them.

  10. High-absorptance high-emittance anodic coating

    NASA Technical Reports Server (NTRS)

    Le, Huong Giang (Inventor); Chesterfield, John L. (Inventor)

    1999-01-01

    A colored anodic coating for use on surfaces of substrates, e.g. aluminum substrates in which it is desirable to maintain a high solar absorptance (.alpha.) and a high infrared emittance (.epsilon.), particularly in low earth orbit space environments. This anodic coating is preferably a dark colored coating, and even more preferably a black coating. This coating allows a touch temperature within an acceptable design range to preclude burning of an astronaut in case of contact, but also allows a solar radiation absorption in an amount such that an .alpha./.epsilon. ratio of unity is achieved. The coating of the invention comprises a first layer in the form of an acid anodized colored anodic layer for achieving a high solar absorptance and a second or high emittance layer in the form of a clear acid anodized layer for achieving a high emittance. The entire coating is quite thin, e.g. 1-2 mils and is quite stable in a hostile space environment of the type encountered in a low earth orbit. The coating is obtained by first creating the high emittance clear anodized coating on the metal surface followed by anodizing using a colored anodizing process.

  11. On the Equivalent Dose for Auger Electron Emitters

    PubMed Central

    Howell, Roger W.; Narra, Venkat R.; Sastry, Kandula S. R.; Rao, Dandamudi V.

    2012-01-01

    Radionuclides that emit Auger electrons are widely used in nuclear medicine (e.g., 99mTc, 123I, 201T1) and biomedical research (e.g., 51Cr, 125I), and they are present in the environment (e.g., 40K, 55Fe). Depending on the subcellular distribution of the radionuclide, the biological effects caused by tissue-incorporated Auger emitters can be as severe as those from high-LET α particles. However, the recently adopted recommendations of the International Commission on Radiological Protection (ICRP) provide no guidance with regard to calculating the equivalent dose for these radionuclides. The present work, using spermatogenesis in mouse testis as the experimental model, shows that the lethality of the prolific Auger emitter 125I is linearly dependent on the fraction of the radioactivity in the organ that is bound to DNA. This suggests that the equivalent dose for Auger emitters may have a similar linear dependence. Accordingly, a formalism for calculating the equivalent dose for Auger emitters is advanced within the ICRP framework. PMID:8475256

  12. Emittance control and RF bunch compression in the NSRRC photoinjector

    NASA Astrophysics Data System (ADS)

    Lau, W. K.; Hung, S. B.; Lee, A. P.; Chou, C. S.; Huang, N. Y.

    2011-05-01

    The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

  13. Silicon photonic crystal thermal emitter at near-infrared wavelengths.

    PubMed

    O'Regan, Bryan J; Wang, Yue; Krauss, Thomas F

    2015-08-21

    Controlling thermal emission with resonant photonic nanostructures has recently attracted much attention. Most of the work has concentrated on the mid-infrared wavelength range and/or was based on metallic nanostructures. Here, we demonstrate the experimental operation of a resonant thermal emitter operating in the near-infrared (≈1.5 μm) wavelength range. The emitter is based on a doped silicon photonic crystal consisting of a two dimensional square array of holes and using silicon-on-insulator technology with a device-layer thickness of 220 nm. The device is resistively heated by passing current through the photonic crystal membrane. At a temperature of ≈1100 K, we observe relatively sharp emission peaks with a Q factor around 18. A support structure system is implemented in order to achieve a large area suspended photonic crystal thermal emitter and electrical injection. The device demonstrates that weak absorption together with photonic resonances can be used as a wavelength-selection mechanism for thermal emitters, both for the enhancement and the suppression of emission.

  14. Improved Photoresist Coating for Making CNT Field Emitters

    NASA Technical Reports Server (NTRS)

    Toda, Risaku; Manohara, Harish

    2009-01-01

    An improved photoresist-coating technique has been developed for use in the fabrication of carbon-nanotube- (CNT) based field emitters is described. The improved photoresist coating technique overcomes what, heretofore, has been a major difficulty in the fabrication process.

  15. Investigation of emittance growth in the White Horse beam

    SciTech Connect

    Jones, M.E.; Lee, H.; Lemons, D.S.

    1984-01-01

    The equilibrium and stability of the neutral gas transport section of the White Horse beam accelerator is studied. It is found that the beam should be unstable from the two-stream instability and from beam-excited ion-acoustic waves, with the latter being a possible source of emittance growth in the beam. 11 references, 16 figures, 1 table.

  16. Tracing ultrafast dynamics of strong fields at plasma-vacuum interfaces with longitudinal proton probing

    SciTech Connect

    Abicht, F.; Braenzel, J.; Koschitzki, Ch.; Schnürer, M.; Priebe, G.; Andreev, A. A.; Nickles, P. V.; Sandner, W.

    2014-07-21

    If regions of localized strong fields at plasma-vacuum interfaces are probed longitudinally with laser accelerated proton beams their velocity distribution changes sensitively and very fast. Its measured variations provide indirectly a higher temporal resolution as deduced from deflection geometries which rely on the explicit temporal resolution of the proton beam at the position of the object to probe. With help of reasonable models and comparative measurements changes of proton velocity can trace the field dynamics even at femtosecond time scale. In longitudinal probing, the very low longitudinal emittance together with a broad band kinetic energy distribution of laser accelerated protons is the essential prerequisite of the method. With a combination of energy and one-dimensional spatial resolution, we resolve fast field changes down to 100 fs. The used pump probe setup extends previous schemes and allows discriminating simultaneously between electric and magnetic fields in their temporal evolution.

  17. Effect of a triaxial nuclear shape on proton tunneling: the decay and structure of 145Tm.

    PubMed

    Seweryniak, D; Blank, B; Carpenter, M P; Davids, C N; Davinson, T; Freeman, S J; Hammond, N; Hoteling, N; Janssens, R V F; Khoo, T L; Liu, Z; Mukherjee, G; Robinson, A; Scholey, C; Sinha, S; Shergur, J; Starosta, K; Walters, W B; Woehr, A; Woods, P J

    2007-08-24

    Gamma rays deexciting states in the proton emitter 145Tm were observed using the recoil-decay tagging method. The 145Tm ground-state rotational band was found to exhibit the properties expected for an h{11/2} proton decoupled band. In addition, coincidences between protons feeding the 2{+} state in 144Er and the 2{+}-->0{+} gamma-ray transition were detected, the first measurement of this kind, leading to a more precise value for the 2{+} excitation energy of 329(1) keV. Calculations with the particle-rotor model and the core quasiparticle coupling model indicate that the properties of the pi{11/2} band and the proton-decay rates in 145Tm are consistent with the presence of triaxiality with an asymmetry parameter gamma approximately 20 degrees .

  18. Effects of Booster Scraping in Polarized Proton Runs 2006 and 2008

    SciTech Connect

    Zhang,S.Y.; Ahrens, L.; Huang, H.; Zeno, K.

    2009-01-02

    Effects of the Booster vertical scraping on the RHIC beam polarization, the RHIC beam emittance, and on the Booster to AGS transfer efficiency and AGS transmission as well, are further studied. In [1], the strong dependence of the RHIC beam polarization and emittance on bunch intensity in proton run 2008 (pp08) is compared with the proton run 2006 (pp06), where the dependence is much weaker. The setting in the AGS Booster, mainly the vertical scraping, is suspected to having played a role in the different patterns in the two runs. In this note, we further study the effects of the Booster vertical scraping on the RHIC beam polarization, and on the RHIC beam emittance as well. With the improvement of the RHIC bunch intensity in mind, the Booster scraping effects on the Booster to AGS transfer (BtA) efficiency and the AGS transmission are also studied. For simplicity and to be more useful, only the RHIC fills after the one-week shutdown in pp06 and the fills using the AGS User 2 in pp08 are shown. For these fills, the machine settings in AGS are similar in pp06 and pp08 runs. Furthermore, this setting might be used for next polarized proton run, at least at the beginning of the run.

  19. Emitter/absorber interface of CdTe solar cells

    SciTech Connect

    Song, Tao; Kanevce, Ana; Sites, James R.

    2016-06-17

    The performance of CdTe solar cells can be very sensitive to their emitter/absorber interfaces, especially for high-efficiency cells with improved bulk properties. When interface defect states are located at efficient recombination energies, performance losses from acceptor-type interface defects can be significant. Numerical simulations show that the emitter/absorber band alignment, the emitter doping and thickness, and the defect properties of the interface (i.e. defect density, defect type, and defect energy) can all play significant roles in the interface recombination. In particular, a type I heterojunction with small conduction-band offset (0.1 eV /= 0.4 eV), however, can impede electron transport and lead to a reduction of photocurrent and fill-factor. In contrast to the spike, a 'cliff' (.delta..EC < 0 eV) is likely to allow many holes in the vicinity of the interface, which will assist interface recombination and result in a reduced open-circuit voltage. In addition, a thin and highly-doped emitter can invert the absorber, form a large hole barrier, and decrease device performance losses due to high interface defect density. CdS is the most common emitter material used in CdTe solar cells, but the CdS/CdTe interface is in the cliff category and is not favorable from the band-offset perspective. Other n-type emitter choices, such as (Mg,Zn)O, Cd(S,O), or (Cd,Mg)Te, can be tuned by varying the elemental ratio for an optimal positive value of ..delta..EC. These materials are predicted to yield higher

  20. Beam Loss and Longitudinal Emittance Growth in SIS

    NASA Astrophysics Data System (ADS)

    Kirk, M.; Hofmann, I.; Boine-Frankenheim, O.; Spiller, P.; Hülsmann, P.; Franchetti, G.; Damerau, H.; König, H. Günter; Klingbeil, H.; Kumm, M.; Moritz, P.; Schütt, P.; Redelbach, A.

    2005-06-01

    Beam losses of several percent occur regularly in SIS. The onset occurs during the RF capture of the beam. Previous studies have revealed that the losses can come from the RF bucket at the start of acceleration being over filled due to the longitudinal bucket acceptance being too small, or due to the mismatch between the mean energy from the UNILAC and synchronous energy of the SIS. The beam losses as measured by a DC beam transformer however show in addition to the sharp initial drop, for the above reasons, a much slower decay in the beam intensity. The speculated cause comes from the incoherent transverse tune shift of the bunched beam, which forces particles into transverse resonant conditions. The longitudinal emittance growth is also another important issue for SIS. Past measurements from Schottky-noise pick-ups have shown a factor of 3-5 increase in the longitudinal emittance depending on the extraction energy; a large factor when compared against expectations from theory. These factors were calculated from the ratio between the normalized relative momentum spread of the DC beam before RF capture and after debunching. In this present work, tomographical techniques have been used to reconstruct the phasespace from a series of bunch profile measurements from a Beam Position Monitor (BPM). Therefore one can find the rate of growth in the longitudinal emittance from a series of high resolution BPM measurements along the RF ramp. Furthermore the initial phasespace density matrix from these reconstructions has been used to generate the initial population of macroparticles for the ESME longitudinal dynamics Particle-In-Cell code, thereby enabling a comparison between the longitudinal emittance growth of the beam under ideal conditions and that of the experiment. The longitudinal emittance growth (rms) during the acceleration (˜540ms) was approximately 20%, and that during the RF capture was estimated to have an upper limit of about 40%. Later measurements have also

  1. Emitter/absorber interface of CdTe solar cells

    NASA Astrophysics Data System (ADS)

    Song, Tao; Kanevce, Ana; Sites, James R.

    2016-06-01

    The performance of CdTe solar cells can be very sensitive to the emitter/absorber interface, especially for high-efficiency cells with high bulk lifetime. Performance losses from acceptor-type interface defects can be significant when interface defect states are located near mid-gap energies. Numerical simulations show that the emitter/absorber band alignment, the emitter doping and thickness, and the defect properties of the interface (i.e., defect density, defect type, and defect energy) can all play significant roles in the interface recombination. In particular, a type I heterojunction with small conduction-band offset (0.1 eV ≤ ΔEC ≤ 0.3 eV) can help maintain good cell efficiency in spite of high interface defect density, much like with Cu(In,Ga)Se2 (CIGS) cells. The basic principle is that positive ΔEC, often referred to as a "spike," creates an absorber inversion and hence a large hole barrier adjacent to the interface. As a result, the electron-hole recombination is suppressed due to an insufficient hole supply at the interface. A large spike (ΔEC ≥ 0.4 eV), however, can impede electron transport and lead to a reduction of photocurrent and fill-factor. In contrast to the spike, a "cliff" (ΔEC < 0 eV) allows high hole concentration in the vicinity of the interface, which will assist interface recombination and result in a reduced open-circuit voltage. Another way to mitigate performance losses due to interface defects is to use a thin and highly doped emitter, which can invert the absorber and form a large hole barrier at the interface. CdS is the most common emitter material used in CdTe solar cells, but the CdS/CdTe interface is in the cliff category and is not favorable from the band-offset perspective. The ΔEC of other n-type emitter choices, such as (Mg,Zn)O, Cd(S,O), or (Cd,Mg)Te, can be tuned by varying the elemental ratio for an optimal positive value of ΔEC. These materials are predicted to yield higher voltages and would therefore be

  2. Emitter/absorber interface of CdTe solar cells

    SciTech Connect

    Song, Tao Sites, James R.; Kanevce, Ana

    2016-06-21

    The performance of CdTe solar cells can be very sensitive to the emitter/absorber interface, especially for high-efficiency cells with high bulk lifetime. Performance losses from acceptor-type interface defects can be significant when interface defect states are located near mid-gap energies. Numerical simulations show that the emitter/absorber band alignment, the emitter doping and thickness, and the defect properties of the interface (i.e., defect density, defect type, and defect energy) can all play significant roles in the interface recombination. In particular, a type I heterojunction with small conduction-band offset (0.1 eV ≤ ΔE{sub C} ≤ 0.3 eV) can help maintain good cell efficiency in spite of high interface defect density, much like with Cu(In,Ga)Se{sub 2} (CIGS) cells. The basic principle is that positive ΔE{sub C}, often referred to as a “spike,” creates an absorber inversion and hence a large hole barrier adjacent to the interface. As a result, the electron-hole recombination is suppressed due to an insufficient hole supply at the interface. A large spike (ΔE{sub C} ≥ 0.4 eV), however, can impede electron transport and lead to a reduction of photocurrent and fill-factor. In contrast to the spike, a “cliff” (ΔE{sub C} < 0 eV) allows high hole concentration in the vicinity of the interface, which will assist interface recombination and result in a reduced open-circuit voltage. Another way to mitigate performance losses due to interface defects is to use a thin and highly doped emitter, which can invert the absorber and form a large hole barrier at the interface. CdS is the most common emitter material used in CdTe solar cells, but the CdS/CdTe interface is in the cliff category and is not favorable from the band-offset perspective. The ΔE{sub C} of other n-type emitter choices, such as (Mg,Zn)O, Cd(S,O), or (Cd,Mg)Te, can be tuned by varying the elemental ratio for an optimal positive value of ΔE{sub C}. These

  3. Using antennas separated in flight direction to avoid effect of emitter clock drift in geolocation

    SciTech Connect

    Ormesher, Richard C.; Bickel, Douglas L

    2012-10-23

    The location of a land-based radio frequency (RF) emitter is determined from an airborne platform. RF signaling is received from the RF emitter via first and second antennas. In response to the received RF signaling, signal samples for both antennas are produced and processed to determine the location of the RF emitter.

  4. Spacecraft charging control by thermal, field emission with lanthanum-hexaboride emitters

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1978-01-01

    Thermal, field emitters of lanthanum (or perhaps cerium) hexaboride (LaB6) with temperature variability up to about 1500K are suggested for spacecraft charging control. Such emitters operate at much lower voltages with considerably more control and add plasma-diagnostic versatility. These gains should outweigh the additional complexity of providing heat for the LaB6 thermal, field emitter.

  5. Experimentally minimized beam emittance from an L-band photoinjector

    NASA Astrophysics Data System (ADS)

    Krasilnikov, M.; Stephan, F.; Asova, G.; Grabosch, H.-J.; Groß, M.; Hakobyan, L.; Isaev, I.; Ivanisenko, Y.; Jachmann, L.; Khojoyan, M.; Klemz, G.; Köhler, W.; Mahgoub, M.; Malyutin, D.; Nozdrin, M.; Oppelt, A.; Otevrel, M.; Petrosyan, B.; Rimjaem, S.; Shapovalov, A.; Vashchenko, G.; Weidinger, S.; Wenndorff, R.; Flöttmann, K.; Hoffmann, M.; Lederer, S.; Schlarb, H.; Schreiber, S.; Templin, I.; Will, I.; Paramonov, V.; Richter, D.

    2012-10-01

    High brightness electron sources for linac based free-electron lasers (FELs) are being developed at the Photo Injector Test facility at DESY, Zeuthen site (PITZ). Production of electron bunches with extremely small transverse emittance is the focus of the PITZ scientific program. The photoinjector optimization in 2008-2009 for a bunch charge of 1, 0.5, 0.25, and 0.1 nC resulted in measured emittance values which are beyond the requirements of the European XFEL [S. Rimjaem , Nucl. Instrum. Methods Phys. Res., Sect. A 671, 62 (2012)NIMAER0168-900210.1016/j.nima.2011.12.101]. Several essential modifications were commissioned in 2010-2011 at PITZ, resulting in further improvement of the photoinjector performance. Significant improvement of the rf gun phase stability is a major contribution in the reduction of the measured transverse emittance. The old TESLA prototype booster was replaced by a new cut disk structure cavity. This allows acceleration of the electron beam to higher energies and supports much higher flexibility for stable booster operation as well as for longer rf pulses which is of vital importance especially for the emittance optimization of low charge bunches. The transverse phase space of the electron beam was optimized at PITZ for bunch charges in the range between 0.02 and 2 nC, where the quality of the beam measurements was preserved by utilizing long pulse train operation. The experimental optimization yielded worldwide unprecedented low normalized emittance beams in the whole charge range studied.

  6. Low Emittance Guns for the ILC Polarized Electron Beam

    NASA Astrophysics Data System (ADS)

    Clendenin, J. E.; Brachmann, A.; Ioakeimidi, K.; Kirby, R. E.; Maruyama, T.; Miller, R. H.; Wang, J. W.; Zhou, F.

    2007-06-01

    Polarized electron beams generated by DC guns are routinely available at several accelerators including JLAB, Mainz and SLAC. These guns operate with a cathode bias on the order of -100 kV. To minimize space charge effects, relatively long bunches are generated at the gun and then compressed longitudinally external to the gun just before and during initial acceleration. For linear colliders, this compression is accomplished using a combination of rf bunchers. For the basic design of the International Linear Collider (ILC), a 120 kV DC photocathode gun is used to produce a series of nanosecond bunches that are each compressed by two sub-harmonic bunchers (SHBs) followed by an L-band buncher and capture section. The longitudinal bunching process results in a significantly higher emittance than produced by the gun alone. While high-energy experiments using polarized beams are not generally sensitive to the source emittance, there are several benefits to a lower source emittance including a simpler more efficient injector system and a lower radiation load during transport especially at bends as at the damping ring. For the ILC, the SHBs could be eliminated if the voltage of the gun is raised sufficiently. Simulations using the General Particle Tracer (GPT) package indicate that a cathode bias voltage of ⩾200 kV should allow both SHBs to be operated at 433 or even 650 MHz, while ⩾500 kV would be required to eliminate the SHBs altogether. Simulations can be used to determine the minimum emittance possible if the injector is designed for a given increased voltage. A possible alternative to the DC gun is an rf gun. Emittance compensation, routinely used with rf guns, is discussed for higher-voltage DC guns.

  7. Coherent polarization locking of a diode emitter array

    NASA Astrophysics Data System (ADS)

    Ng, S. P.; Phua, P. B.

    2010-02-01

    Coherent beam combining has been actively explored as a technique to increase the brightness of laser sources. Passive phase-locking of a diode array in a common resonator, in particular, is an attractive approach owing to its inherent simplicity and good beam quality. In this work, we present the coherent combining of an array of diode emitters in a conventional diode bar configuration using the coherent polarization locking technique. An external laser cavity is designed so that the diode emissions from several 976 nm diode emitters are spatially overlapped via a series of birefringent walk-off crystals and passively phase-locked by a polarizing beam splitter. The key optical element in this beam combining scheme is the novel YVO4 birefringent spatial beam combiner that not only provides spatial overlap, but also identical optical path lengths for the diode beams. This facilitates design of the cavity for achieving a close match between the mode size of the Gaussian beam and the asymmetric emitting area at the front facet of the diode emitters. The phase-locking technique, coupled with the required standard bulk optical crystals and standard diode bar configuration, yields a robust laser architecture which retains the advantages of diode lasers in terms of cost, size and wavelength tunability. With the coherent combining of four diode emitters, we achieved a nearly diffraction limited beam at 1030 mW, which represents a 50 times increase in brightness over the standard incoherent diode bar. The coherent locking approach is highly scalable. Further experiments to coherently combine eight to sixteen diode emitters are in progress.

  8. The Schwarzschild Proton

    SciTech Connect

    Haramein, Nassim

    2010-11-24

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

  9. SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC. Design of a multi-cusp ion source for proton therapy

    NASA Astrophysics Data System (ADS)

    Wu, Xiao-Bing; Huang, Tao; Ouyang, Hua-Fu; Zhang, Hua-Shun; Gong, Ke-Yun

    2010-12-01

    The permanent magnets of the discharge chamber in a multi-cusp proton source are studied and designed. The three electrode extraction system is adopted and simulated. A method to extract different amounts of current while keeping the beam emittance unchanged is proposed.

  10. Surface Protonics Promotes Catalysis

    NASA Astrophysics Data System (ADS)

    Manabe, R.; Okada, S.; Inagaki, R.; Oshima, K.; Ogo, S.; Sekine, Y.

    2016-12-01

    Catalytic steam reforming of methane for hydrogen production proceeds even at 473 K over 1 wt% Pd/CeO2 catalyst in an electric field, thanks to the surface protonics. Kinetic analyses demonstrated the synergetic effect between catalytic reaction and electric field, revealing strengthened water pressure dependence of the reaction rate when applying an electric field, with one-third the apparent activation energy at the lower reaction temperature range. Operando–IR measurements revealed that proton conduction via adsorbed water on the catalyst surface occurred during electric field application. Methane was activated by proton collision at the Pd–CeO2 interface, based on the inverse kinetic isotope effect. Proton conduction on the catalyst surface plays an important role in methane activation at low temperature. This report is the first describing promotion of the catalytic reaction by surface protonics.

  11. Electron-proton spectrometer

    NASA Technical Reports Server (NTRS)

    Winckler, J. R.

    1973-01-01

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

  12. Surface Protonics Promotes Catalysis

    PubMed Central

    Manabe, R.; Okada, S.; Inagaki, R.; Oshima, K.; Ogo, S.; Sekine, Y.

    2016-01-01

    Catalytic steam reforming of methane for hydrogen production proceeds even at 473 K over 1 wt% Pd/CeO2 catalyst in an electric field, thanks to the surface protonics. Kinetic analyses demonstrated the synergetic effect between catalytic reaction and electric field, revealing strengthened water pressure dependence of the reaction rate when applying an electric field, with one-third the apparent activation energy at the lower reaction temperature range. Operando–IR measurements revealed that proton conduction via adsorbed water on the catalyst surface occurred during electric field application. Methane was activated by proton collision at the Pd–CeO2 interface, based on the inverse kinetic isotope effect. Proton conduction on the catalyst surface plays an important role in methane activation at low temperature. This report is the first describing promotion of the catalytic reaction by surface protonics. PMID:27905505

  13. Self-regulation of discharge in non-compensating subsurface drip irrigation emitters

    NASA Astrophysics Data System (ADS)

    Gil-Rodríguez, María; Rodríguez-Sinobas, Leonor; Sánchez, Raúl; Juana, Luis; Castañón, Guillermo

    2014-05-01

    While studying emitter discharge variability of subsurface drip irrigation (SDI) in the laboratory, the authors found out a possible self-regulation effect of non-compensating emitter discharge. This is due to the interaction between effects of emitter discharge and soil pressure. As known, under certain circumstances, a positive pressure hs develops at the discharge point of a buried emitter. The hydraulic gradient between the emitter interior and the soil would then decrease compared to the situation where the emitter is on the surface. Thus, the discharge reduces, following: q=k·(h_0-h_s)x, where q is the emitter flow rate, h0 is the working pressure head, and k and x are the emitter coefficient and exponent, respectively. The soil pressure would act as a regulator. The emitters with a greater flow rate in surface irrigation would generate a higher pressure in the soil. Therefore, the subsurface irrigation discharge would be reduced to a greater extent than in emitters with a lower flow rate. Consequently, the flow emitter variability would be smaller in buried emitters than in surface ones. The above interaction would not be observed in compensating emitters, even for the same or greater soil pressure variability. Their elastomers keep the flow rate constant within a compensation range, provided that the hydraulic gradient between the emitter interior and the soil pressure is higher than the lower limit of this range. To confirm this hypothesis, simulations were performed for both uniform and heterogeneous soils reproducing the laboratory conditions (working pressure head and emitter discharge). When the soil has a high heterogeneity, the self-regulation effect was very small as compared to the variability caused by the soil. Nevertheless, the authors consider that this effect is worth to be studied. The objective of the paper is to perform new simulations in order to determine under which circumstances self-regulation would be significant and find thresholds

  14. Proton-proton colliding beam facility ISABELLE

    SciTech Connect

    Hahn, H

    1980-01-01

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

  15. Experimental study of coherent synchrotron radiation in the emittance exchange line at the A0-photoinjector

    SciTech Connect

    Thangaraj, Jayakar C.T.; Thurman-Keup, R.; Johnson, A.; Lumpkin, A.H.; Edwards, H.; Ruan, J.; Santucci, J.; Sun, Y.E.-; Church, M.; Piot, P.; /Fermilab /Northern Illinois U.

    2010-08-01

    Next generation accelerators will require a high current, low emittance beam with a low energy spread. Such accelerators will employ advanced beam conditioning systems such as emittance exchanger to manipulate high brightness beams. One of the goals of the Fermilab A0 photoinjector is to investigate the transverse to longitudinal emittance exchange principle. Coherent synchrotron radiation could limit high current operation of the emittance exchanger. In this paper, we report on the preliminary experimental and simulation study of the coherent synchroton radiation (CSR) in the emittance exchange line at A0 photoinjector.

  16. High-current lanthanum-hexaboride electron emitter for a quasi-stationary arc plasma generator

    SciTech Connect

    Davydenko, V. I. Ivanov, A. A. Shul’zhenko, G. I.

    2015-11-15

    A high-current electron emitter on the basis of lanthanum hexaboride is developed for quasi-stationary arc plasma generators of ion sources. The emitter consists of a set of LaB{sub 6} washers interleaved with washers made of thermally extended graphite. The emitter is heated by the current flowing through the graphite washers. The thermal regime of emitter operation during plasma generation is considered. The emitter has been successfully used in the ion sources of the diagnostic injectors of fast hydrogen atomic beams.

  17. Emittance Measurements from a Laser Driven Electron Injector

    SciTech Connect

    Reis, David A

    2003-07-28

    The Gun Test Facility (GTF) at the Stanford Linear Accelerator Center was constructed to develop an appropriate electron beam suitable for driving a short wavelength free electron laser (FEL) such as the proposed Linac Coherent Light Source (LCLS). For operation at a wavelength of 1.5 {angstrom}, the LCLS requires an electron injector that can produce an electron beam with approximately 1 {pi} mm-mrad normalized rms emittance with at least 1 nC of charge in a 10 ps or shorter bunch. The GTF consists of a photocathode rf gun, emittance-compensation solenoid, 3 m linear accelerator (linac), drive laser, and diagnostics to measure the beam. The rf gun is a symmetrized 1.6 cell, s-band high gradient, room temperature, photocathode structure. Simulations show that this gun when driven by a temporally and spatially shaped drive laser, appropriately focused with the solenoid, and further accelerated in linac can produce a beam that meets the LCLS requirements. This thesis describes the initial characterization of the laser and electron beam at the GTF. A convolved measurement of the relative timing between the laser and the rf phase in the gun shows that the jitter is less than 2.5 ps rms. Emittance measurements of the electron beam at 35 MeV are reported as a function of the (Gaussian) pulse length and transverse profile of the laser as well as the charge of the electron beam at constant phase and gradient in both the gun and linac. At 1 nC the emittance was found to be {approx} 13 {pi} mm-mrad for 5 ps and 8 ps long laser pulses. At 0.5 nC the measured emittance decreased approximately 20% in the 5 ps case and 40% in the 8 ps case. These measurements are between 40-80% higher than simulations for similar experimental conditions. In addition, the thermal emittance of the electron beam was measured to be 0.5 {pi} mm-mrad.

  18. Emittance measurements from a laser-driven electron injector

    NASA Astrophysics Data System (ADS)

    Reis, David A.

    1999-11-01

    The Gun Test Facility (GTF) at the Stanford Linear Accelerator Center was constructed to develop an appropriate electron beam suitable for driving a short wavelength free electron laser (FEL) such as the proposed Linac Coherent Light Source (LCLS). For operation at a wavelength of 1.5 Å, the LCLS requires an electron injector that can produce an electron beam with approximately I π mm-mrad normalized rms emittance with at least 1 nC of charge in a 10 ps or shorter bunch. The GTF consists of a photocathode rf gun, emittance- compensation solenoid, 3 m linear accelerator (linac), drive laser, and diagnostics to measure the beam. The rf gun is a symmetrized 1.6 cell, S-band, high gradient, room temperature, photocathode structure. Simulations show that this gun when driven by a temporally and spatially shaped drive laser, appropriately focused with the solenoid, and further accelerated in linac can produce a beam that meets the LCLS requirements. This thesis describes the initial characterization of the laser and electron beam at the GTF. A convolved measurement of the relative timing between the laser and the rf phase in the gun shows that the jitter is less than 2.5 ps rms. Emittance measurements of the electron beam at 35 MeV are reported as a function of the (Gaussian) pulse length and transverse profile of the laser as well as the charge of the electron beam at constant phase and gradient in both the gun and linac. At 1 nC the emittance was found to be ~13 π mm-mrad for 5 ps, and 8 ps long laser pulses. At 0.5 nC the measured emittance decreased approximately 20% in the 5 ps case and 40% in the 8 ps case. These measurements are between 40-80% higher than simulations for similar experimental conditions. In addition, the thermal emittance of the electron beam was measured to be 0.15 π mm-mrad.

  19. Parallel nanomanufacturing via electrohydrodynamic jetting from microfabricated externally-fed emitter arrays

    NASA Astrophysics Data System (ADS)

    Ponce de Leon, Philip J.; Hill, Frances A.; Heubel, Eric V.; Velásquez-García, Luis F.

    2015-06-01

    We report the design, fabrication, and characterization of planar arrays of externally-fed silicon electrospinning emitters for high-throughput generation of polymer nanofibers. Arrays with as many as 225 emitters and with emitter density as large as 100 emitters cm-2 were characterized using a solution of dissolved PEO in water and ethanol. Devices with emitter density as high as 25 emitters cm-2 deposit uniform imprints comprising fibers with diameters on the order of a few hundred nanometers. Mass flux rates as high as 417 g hr-1 m-2 were measured, i.e., four times the reported production rate of the leading commercial free-surface electrospinning sources. Throughput increases with increasing array size at constant emitter density, suggesting the design can be scaled up with no loss of productivity. Devices with emitter density equal to 100 emitters cm-2 fail to generate fibers but uniformly generate electrosprayed droplets. For the arrays tested, the largest measured mass flux resulted from arrays with larger emitter separation operating at larger bias voltages, indicating the strong influence of electrical field enhancement on the performance of the devices. Incorporation of a ground electrode surrounding the array tips helps equalize the emitter field enhancement across the array as well as control the spread of the imprints over larger distances.

  20. Beta-Delayed Neutron Emission in Neutron-Rich Nuclei

    NASA Astrophysics Data System (ADS)

    Marketin, Tomislav; Sieverding, André; Wu, Meng-Ru; Paar, Nils; Martínez-Pinedo, Gabriel

    β-delayed neutron emission is the process of emission of one or more neutrons, after β-decay, from the excited daughter nucleus. The probabilities of emission are an important physical quantity in a variety of nuclear physics applications, from the simulations of heavy element nucleosynthesis to control of reactor power levels and nuclear waste management. However, it is relatively difficult to measure and much less data is available than for β-decay, particularly for nuclei that are expected to take part in the r-process. In this work we will present a calculation of β-decay half-lives and β-delayed neutron emission probabilities in neutron-rich nuclei using the transition strength obtained with a microscopic model combined with a statistical calculation of level densities. We explore the effect of altered emission probabilities, with respect to the simple calculation, on the r-process.