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Sample records for 3-20 mev electrons

  1. The Proposed 2 MeV Electron Cooler for COSY

    SciTech Connect

    Dietrich, Juergen; Parkhomchuk, Vasily V.; Reva, Vladimir B.; Vedenev, Maxim A.

    2006-03-20

    The design, construction and installation of a 2 MeV electron cooling system for COSY is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the design of the 2 MeV electron cooler for COSY is intended to test some new features of the high energy electron cooler for HESR at GSI. The design of the 2 MeV electron cooler will be accomplished in cooperation with the Budker Institute of Nuclear Physics in Novosibirsk, Russia. Starting with the boundary conditions of the existing electron cooler at COSY the requirements and a first general scheme of the 2 MeV electron cooler are described.

  2. Femtosecond time-resolved MeV electron diffraction

    SciTech Connect

    Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; Wu, L.; Cao, J.; Berger, H.; Geck, J.; Kraus, R.; Pjerov, S.; Shen, Y.; Tobey, R. I.; Hill, J. P.; Wang, X. J.

    2015-06-02

    We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 fC (~3 × 104 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated by observing the evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.

  3. Femtosecond time-resolved MeV electron diffraction

    DOE PAGESBeta

    Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; Wu, L.; Cao, J.; Berger, H.; Geck, J.; Kraus, R.; Pjerov, S.; Shen, Y.; et al

    2015-06-02

    We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 fC (~3 × 104 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated by observing themore » evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.« less

  4. 10MeV 25KW industrial electron LINAC

    NASA Astrophysics Data System (ADS)

    Kamino, Y.

    1998-06-01

    A 10MeV 25KW plus class electron LINAC was developed for sterilisation of medical devices. The LINAC composed of a standing wave type single cavity prebuncher and a 2m electro-plated travelling wave guide uses a 5MW 2856MHz pulse klystron as an RF source and provides 25KW beam power at the Ti alloy beam window stably after the energy analysing magnet with 10MeV plus-minus 1 MeV energy slit. The practical maximum beam power reached 29 KW and this demonstrated the LINAC as one of the most powerful S-band electron LINACs in the world. The control of the LINAC is fully automated and the "One-Button Operation" is realised, which is valuable for easy operation as a plant system. 2 systems have been delivered and are being operated stably.

  5. Temporal Structure of MeV Electron Precipitation

    NASA Astrophysics Data System (ADS)

    Millan, R. M.; Lorentzen, K. R.; Lin, R. P.; Smith, D. M.

    2001-12-01

    On January 12, 2000, the MAXIS (MeV Auroral X-ray Imaging and Spectroscopy) long duration balloon experiment was launched from McMurdo, Antarctica carrying x-ray instrumentation designed to search for MeV electron precipitation similar to the event observed in 1996 over Kiruna, Sweden (L=5.8). MAXIS detected seven x-ray bursts with significant flux extending above 0.8 MeV during the 18 day flight in addition to extended periods of softer X-ray activity. These seven events are characterized by an extremely flat spectrum ( ~E-1.7) indicating that the bulk of precipitating electrons producing the x-rays is at relativistic energies. The bursts were detected between magnetic latitudes 58o-67o (corresponding to L-values between 3.8-6.7) with durations varying from several minutes to several hours. The MeV bursts were found to occur preferentially in the late afternoon/dusk sectors (14:30-00:00 MLT) while softer precipitation was detected at all magnetic local times. Two of the strongest MeV events detected by MAXIS show strong modulation of the x-ray count rate at ULF timescales ( ~150 s) similar to modulations observed during the Kiruna event at 100-200 s. We present results from temporal analysis of the MAXIS germanium spectrometer data and examine ground-based and spacecraft observations for evidence of coincident ULF wave activity.

  6. Pohang Neutron Facility Based on 100 Mev Electron Linac

    NASA Astrophysics Data System (ADS)

    Kim, G. N.; Ahmed, H.; Machrafi, R.; Son, D.; Lee, Y. S.; Skoy, V.; Kang, H. S.; Cho, M. H.; Ko, I. S.; Namkung, W.

    2003-06-01

    Pohang Neutron Facility (PNF) is a pulsed neutron facility based on the 100-MeV electron linear accelerator. It was constructed for nuclear data production in Korea, and it consists of an electron linear accelerator, a water-cooled Ta target with a water moderator and a time-of-flight path with an 11 m length. The 100-MeV electron linac uses a thermionic RF-gun, an alpha magnet, four quadrupole magnets, two SLAC-type accelerating sections, a quadrupole triplet, and a beam-analyzing magnet. It has been equipped with a new four-position sample changer controlled remotely by a CAMAC data acquisition system, which allows the simultaneous accumulation of the neutron time-of-flight spectra from 4 different samples. The neutron total cross sections of natural In and Cu have been measured in the neutron energy range from 0.1 eV to 100 eV by the neutron time-of-flight method.

  7. Lipowitz metal shielding thickness for dose reduction of 6-20 MeV electrons.

    PubMed

    Purdy, J A; Choi, M C; Feldman, A

    1980-01-01

    The relative dose reduction by Lipowitz metal of 6 to 20 MeV electrons from a Varian Associates Clinac-20 linear accelerator has been measured using a parallel plate thin wall ionization chamber. Metal thickness required for a 5% attenuation level for a 10 X 10 cm2 field are as follows: 6 MeV-2.3 mm, 9 MeV-4.4 mm, 12 MeV-8.5 mm, 16 MeV--18.0 mm, 20 MeV-25.0 mm. PMID:7393151

  8. 5MeV Electron Beam Facilities in Japan

    NASA Astrophysics Data System (ADS)

    Mizusawa, K.; Kashiwagi, M.; Hoshi, Y.

    1998-06-01

    There are 3 facilities with 5MeV electron beam processing machines in Japan and another one is planned to start operation in 1998. 2 of them are installed by Nissin-High Voltage and the other are by Sumitomo Heavy/Radiation Dynamics. In this report are introduced 2 facilities which we have installed and are operating satisfactorily. The first one was: installed at Radia Industry for irradiation services and the second one for in-house use in a factory of a pharmaceutical plastic container manufacturer, Shinko Chemical. And the second one is available for contract irradiation. The machine in Radia Industry has a comprehensive conveyor system with a turn-over equipment to shoot from the top and the bottom of materials with e-beam and X-ray, and has been successfully operated for many years. The machine in Shinko Chemical is equipped with a unique conveyor system with two conveyor lines under the beam window and the motion of the lines are opposite each other. This conveyor system also has a turn-over equipment like other machines but the direction of turning-over is designed to give the irradiated materials more uniform dose.

  9. Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies

    NASA Astrophysics Data System (ADS)

    Abbott, D.; Adderley, P.; Adeyemi, A.; Aguilera, P.; Ali, M.; Areti, H.; Baylac, M.; Benesch, J.; Bosson, G.; Cade, B.; Camsonne, A.; Cardman, L. S.; Clark, J.; Cole, P.; Covert, S.; Cuevas, C.; Dadoun, O.; Dale, D.; Dong, H.; Dumas, J.; Fanchini, E.; Forest, T.; Forman, E.; Freyberger, A.; Froidefond, E.; Golge, S.; Grames, J.; Guèye, P.; Hansknecht, J.; Harrell, P.; Hoskins, J.; Hyde, C.; Josey, B.; Kazimi, R.; Kim, Y.; Machie, D.; Mahoney, K.; Mammei, R.; Marton, M.; McCarter, J.; McCaughan, M.; McHugh, M.; McNulty, D.; Mesick, K. E.; Michaelides, T.; Michaels, R.; Moffit, B.; Moser, D.; Muñoz Camacho, C.; Muraz, J.-F.; Opper, A.; Poelker, M.; Réal, J.-S.; Richardson, L.; Setiniyaz, S.; Stutzman, M.; Suleiman, R.; Tennant, C.; Tsai, C.; Turner, D.; Ungaro, M.; Variola, A.; Voutier, E.; Wang, Y.; Zhang, Y.; PEPPo Collaboration

    2016-05-01

    The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19 MeV /c , limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.

  10. [Simulation of an instrumental head for 6 MeV electron beam therapy].

    PubMed

    Albini, E; Belletti, S; Corrado, F; Galelli, M; Mascaro, L

    1990-10-01

    Simulation of a therapy head for 6 MeV electron beams. We present the results of a simulation, performed using a Monte Carlo method, of depth dose curves in water for electron beams of initial kinetic energy of 6.4 MeV, generated by a radiotherapy microtron MM22 Scanditronix. The Fortran code in EGS4: comparison is made between simulated curves, obtained using various approximation criteria, and the experimental one. PMID:2251422

  11. Upper limit on the inner radiation belt MeV electron intensity

    PubMed Central

    Li, X; Selesnick, RS; Baker, DN; Jaynes, AN; Kanekal, SG; Schiller, Q; Blum, L; Fennell, J; Blake, JB

    2015-01-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Key Points Quantified upper limit of MeV electrons in the inner belt Actual MeV electron intensity likely much lower than the upper limit More detailed understanding of relativistic electrons in the magnetosphere PMID:26167446

  12. Interplanetary MeV electrons of Jovian origin

    NASA Technical Reports Server (NTRS)

    Teegarden, B. J.; Mcdonald, F. B.; Trainor, J. H.; Webber, W. R.; Roelof, E. C.

    1974-01-01

    Observations of low energy electron increases observed in interplanetary space on Pioneer 10 are reported as it approached Jupiter. These discrete bursts were several hundred times the normal quiet-time electron flux, and became more frequent as one approached Jupiter resulting in the quasi-continuous presence of large fluxes of these electrons in interplanetary space. It is noted that the integrated flux from quiet-time electrons is comparable to the integrated ambient electron flux itself. In addition, the spectrum of electrons observed in Jupiter's magnetosphere, on Pioneer 10 in interplanetary space near Jupiter, for the quiet-time increases near the earth, and for the ambient electron spectrum are all remarkably similar. These two lines of evidence suggest the possibility that Jupiter could be the source of most of the ambient electrons at low energies.

  13. Performance of the compact 300 MeV electron ring JSR

    NASA Astrophysics Data System (ADS)

    Yokomizo, H.; Yanagida, K.; Harada, S.; Mashiko, K.; Yokoyama, M.; Hashimoto, H.; Nakayama, K.; Kabasawa, M.; Harami, T.; Suzuki, Y.

    1990-05-01

    A compact ring, JSR, has been constructed in a short period of 15 months. The magnets, vacuum chamber and rf system are well manufactured, coming up to the design expectation. The good-field region {ΔB}/{B} < 2 × 10 -4 extends over ±45 mm in the dipole magnets. The base pressure has reached 3 × 10 -10 Torr at the pump head. An electron beam was successfully injected from a linac at an energy of ˜ 150 MeV, and electrons were smoothly accelerated and stored in JSR at a maximum energy of 300 MeV. The lifetime of the stored electrons is ˜ 30 min, which is mainly determined by collisions with the residual gas in the vacuum chamber. JSR has proved to work correctly in the storage and acceleration of electrons within an energy range from 150 to 300 MeV.

  14. Effect of 1.33 Mev gamma radiation and 0.5 Mev electrons on the mechanical properties of graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Fornes, R. E.; Memory, J. D.; Naranong, N.

    1982-01-01

    Epoxy/graphite fiber, polyimide/graphite fiber, and polysulfone/graphite fiber composites were exposed to 1.33 Mev gamma irradiation and 0.5 Mev electron bombardment for varying periods of time. The effects of the irradiation treatments on the breaking stress and Young's modulus were studied by a three point bending test. Effects were small; both electron radiation up to 5000 Mrad and gamma radiation up to 350 Mrad resulted in slight increases in both stress and modulus.

  15. Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies.

    PubMed

    Abbott, D; Adderley, P; Adeyemi, A; Aguilera, P; Ali, M; Areti, H; Baylac, M; Benesch, J; Bosson, G; Cade, B; Camsonne, A; Cardman, L S; Clark, J; Cole, P; Covert, S; Cuevas, C; Dadoun, O; Dale, D; Dong, H; Dumas, J; Fanchini, E; Forest, T; Forman, E; Freyberger, A; Froidefond, E; Golge, S; Grames, J; Guèye, P; Hansknecht, J; Harrell, P; Hoskins, J; Hyde, C; Josey, B; Kazimi, R; Kim, Y; Machie, D; Mahoney, K; Mammei, R; Marton, M; McCarter, J; McCaughan, M; McHugh, M; McNulty, D; Mesick, K E; Michaelides, T; Michaels, R; Moffit, B; Moser, D; Muñoz Camacho, C; Muraz, J-F; Opper, A; Poelker, M; Réal, J-S; Richardson, L; Setiniyaz, S; Stutzman, M; Suleiman, R; Tennant, C; Tsai, C; Turner, D; Ungaro, M; Variola, A; Voutier, E; Wang, Y; Zhang, Y

    2016-05-27

    The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19  MeV/c, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community. PMID:27284661

  16. Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies

    DOE PAGESBeta

    Abbott, D.; Adderley, P.; Adeyemi, A.; Aguilera, P.; Ali, M.; Areti, H.; Baylac, M.; Benesch, J.; Bosson, G.; Cade, B.; et al

    2016-05-27

    The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19~MeV/c, limited only by the electron beam polarization. We report that this technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.

  17. The 500-MeV, 2 1/2% duty factor linear electron accelerator (MEA)

    SciTech Connect

    Bruinsma, P.J.T.; Kroes, F.B.; Kuijer, L.H.; Noomen, J.G.; Spelt, J.B.; Vogel, A.G.C.

    1983-08-01

    Although the intermediate energy electron accelerator in Amsterdam has not reached completely its design specifications, since early 1981 a fully grown scientific program has developed using beams with an energy ranging from 20 to 120 MeV in the 140 MeV substation (for radio-chemistry and low-energy electron scattering over 180/sup 0/) and from 70 to 400 MeV in the high energy stations for electron scattering and physics with pion and muon beams. A brief description of the MIT-type accelerator and its performance will be given with emphasis on typical features of the machine. Some examples will be given of recently obtained scientific data from which can be derived that the quality of the beam is in full accordance with the high performance level of the scientific equipment, involving a complex beam transport system and a pair of spectrometers for high resolution (1x10/sup -4/) work.

  18. Experimental demonstration of high quality MeV ultrafast electron diffraction.

    PubMed

    Li, Renkai; Tang, Chuanxiang; Du, Yingchao; Huang, Wenhui; Du, Qiang; Shi, Jiaru; Yan, Lixin; Wang, Xijie

    2009-08-01

    The simulation optimization and an experimental demonstration of improved performances of mega-electron-volt ultrafast electron diffraction (MeV UED) are reported in this paper. Using ultrashort high quality electron pulses from an S-band photocathode rf gun and a polycrystalline aluminum foil as the sample, we experimentally demonstrated an improved spatial resolution of MeV UED, in which the Debye-Scherrer rings of the (111) and (200) planes were clearly resolved. This result showed that MeV UED is capable to achieve an atomic level spatial resolution and a approximately 100 fs temporal resolution simultaneously, and will be a unique tool for ultrafast structural dynamics studies. PMID:19725647

  19. The evaluation of 6 and 18 MeV electron beams for small animal irradiation

    NASA Astrophysics Data System (ADS)

    Chao, T. C.; Chen, A. M.; Tu, S. J.; Tung, C. J.; Hong, J. H.; Lee, C. C.

    2009-10-01

    A small animal irradiator is critical for providing optimal radiation dose distributions for pre-clinical animal studies. This paper focuses on the evaluation of using 6 or 18 MeV electron beams as small animal irradiators. Compared with all other prototypes which use photons to irradiate small animals, an electron irradiator has many advantages in its shallow dose distribution. Two major approaches including simulation and measurement were used to evaluate the feasibility of applying electron beams in animal irradiation. These simulations and measurements were taken in three different fields (a 6 cm × 6 cm square field, and 4 mm and 30 mm diameter circular fields) and with two different energies (6 MeV and 18 MeV). A PTW Semiflex chamber in a PTW-MP3 water tank, a PTW Markus chamber type 23343, a PTW diamond detector type 60003 and KODAK XV films were used to measure PDDs, lateral beam profiles and output factors for either optimizing parameters of Monte Carlo simulation or to verify Monte Carlo simulation in small fields. Results show good agreement for comparisons of percentage depth doses (<=2.5% for 6 MeV e; <=1.8% for 18 MeV e) and profiles (FWHM <= 0.5 mm) between simulations and measurements on the 6 cm field. Greater deviation can be observed in the 4 mm field, which is mainly caused by the partial volume effects of the detectors. The FWHM of the profiles for the 18 MeV electron beam is 32.6 mm in the 30 mm field, and 4.7 mm in the 4 mm field at d90. It will take 1-13 min to complete one irradiation of 5-10 Gy. In addition, two different digital phantoms were also constructed, including a homogeneous cylindrical water phantom and a CT-based heterogeneous mouse phantom, and were implemented into Monte Carlo to simulate dose distribution with different electron irradiations.

  20. Ultrafast electron diffraction with megahertz MeV electron pulses from a superconducting radio-frequency photoinjector

    SciTech Connect

    Feng, L. W.; Lin, L.; Huang, S. L.; Quan, S. W.; Hao, J. K.; Zhu, F.; Wang, F.; Liu, K. X.; Jiang, T.; Zhu, P. F.; Fu, F.; Wang, R.; Zhao, L.; Xiang, D.

    2015-11-30

    We report ultrafast relativistic electron diffraction operating at the megahertz repetition rate where the electron beam is produced in a superconducting radio-frequency (rf) photoinjector. We show that the beam quality is sufficiently high to provide clear diffraction patterns from gold and aluminium samples. With the number of electrons, several orders of magnitude higher than that from a normal conducting photocathode rf gun, such high repetition rate ultrafast MeV electron diffraction may open up many new opportunities in ultrafast science.

  1. MeV electrons in Saturn's high-latitude, cusp region

    NASA Astrophysics Data System (ADS)

    Roussos, E.; Krupp, N.; Paranicas, C.

    2013-09-01

    Saturn's electron radiation belts extend on average up to a dipole L-shell of 7. Their structure, however, is highly variable. The outer boundary of these belts has occasionally been observed to drop at L=4 (second half of 2011) or expand up to L=14 (early 2006). Electrons in these belts have considerable fluxes only up to few hundred keV. Energetic electrons above the MeV range are found at low L-shells, in the stable trapping region, as expected. Beyond the belt's outer boundary, energetic electron spectra may reach up to about 300 keV during crossings Saturn's plasma sheet or at the high-latitude magnetosphere, especially when Cassini's MIMI/LEMMS detector is oriented along the magnetic field. MeV electron channels of LEMMS are typically at background levels. However, during several high-latitude crossings of Saturn's magnetosphere (mostly in 2008), LEMMS data show evidence of MeV electrons. Fluxes of these electrons are so high that even cause a considerable penetrating radiation signal in various LEMMS channels. Duration of these events lasts from several minutes up to about an hour. Data on the angular distribution is limited, but it appears that these electrons are not concentrated only along the field-aligned direction, meaning that part of the electrons may remain trapped in the quadrapole configuration of Saturn's cusp. The episodic and transient character of these events indicates that these electrons are accelerated to MeV energies locally, similar to what has been observed at Earth. Apart from presenting these unique LEMMS observations, we will also discuss the implications about the cusp as a universal source of radiation belt electrons in planetary magnetospheres, These observations may also be relevant for the upcoming Juno/JEDI observations at Jupiter.

  2. MeV electron irradiation of Si-SiO2 structures with magnetron sputtered oxide

    NASA Astrophysics Data System (ADS)

    Kaschieva, S.; Angelov, Ch; Dmitriev, S. N.

    2016-03-01

    MeV electrons influence on the characteristics of Si-SiO2 structure with magnetron sputtered oxide was studied by ellipsometry and the thermally stimulated current (TSC) method. The MOS structures used in this study were fabricated on <100> oriented p-Si wafers of 12.75-17,25 Ω.cm resistivity. Magnetron sputtered oxides with different thicknesses of 20 and 100 nm were deposited on p-Si substrates. Both groups of samples were irradiated by 23 MeV electrons. The oxide thicknesses and TSC characteristics of the MOS samples were measured before and after MeV electron irradiation with doses of 4.8×1015 and 4.8×1016 el.cm-2. The oxide thicknesses of both groups of samples increased after irradiation. The main defects generated by the MeV electrons were evaluated. It was shown that the trap concentration increases with the electron irradiation dose. The main peak in the TSC characteristics gives information about the main radiation defects at the Si-SiO2 interface of the MOS structures. These defects can be related to the vacancy-boron complexes which are associated with the main impurities in the p-Si substrate. These results correspond to our results reported earlier for MeV electron irradiated Si-SiO2 structures with thermally grown oxide. But (in this case) the effects observed are more pronounced for the magnetron sputtered oxide. A possible reason is the higher defect concentration generated in the magnetron sputtered oxide during its deposition on Si-substrates.

  3. Energy monitoring device for 1.5-2.4 MeV electron beams

    NASA Astrophysics Data System (ADS)

    Fuochi, P. G.; Lavalle, M.; Martelli, A.; Kovács, A.; Mehta, K.; Kuntz, F.; Plumeri, S.

    2010-03-01

    An easy-to-use and robust energy monitoring device has been developed for reliable detection of day-to-day small variations in the electron beam energy, a critical parameter for quality control and quality assurance in industrial radiation processing. It has potential for using on-line, thus providing real-time information. Its working principle is based on the measurement of currents, or charges, collected by two aluminium absorbers of specific thicknesses (dependent on the beam energy), insulated from each other and positioned within a faraday cup-style aluminium cage connected to the ground. The device has been extensively tested in the energy range of 4-12 MeV under standard laboratory conditions at Institute of Isotopes and CNR-ISOF using different types of electron accelerators; namely, a TESLA LPR-4 LINAC (3-6 MeV) and a L-band Vickers LINAC (7-12 MeV), respectively. This device has been also tested in high power electron beam radiation processing facilities, one equipped with a 7-MeV LUE-8 linear accelerator used for crosslinking of cables and medical device sterilization, and the other equipped with a 10 MeV Rhodotron TT100 recirculating accelerator used for in-house sterilization of medical devices. In the present work, we have extended the application of this method to still lower energy region, i.e. from 1.5 to 2.4 MeV. Also, we show that such a device is capable of detecting deviation in the beam energy as small as 40 keV.

  4. A small 1 MeV electron accelerator for measuring heavy metal concentrations in smokestack gases

    NASA Astrophysics Data System (ADS)

    Reppond, A.; Redden, D. P.; Meitzler, C. R.; Swenson, D. A.

    1997-05-01

    A low-current electron beam may be used as a diagnostic tool to measure the concentrations of heavy metals (Cd, Pb, Hg) present in the flue gas particulates produced by smelters or cement kilns. A small electron accelerator is being constructed as part of a prototype emissions monitoring system. The electron beam energy has a design energy of 1 MeV, a peak current of 5 mA, and a duty factor of 0.1 percent. In this paper, we discuss the results of a set of EGS4 calculations used to model the transport properties of a 1 MeV electron beam passing through a thin vacuum window and the flue gas. Since the accelerator will be mounted in a harsh environment, we have investigated the effects of temperature variations on the linac structure and RF power source. The present status of the accelerator construction project is presented.

  5. Fast electron production in collisions of swift heavy ions (20 MeV/ u < E < 100 MeV/ u) with foils of solids

    NASA Astrophysics Data System (ADS)

    Lanzanò, G.; De Filippo, E.; Rothard, H.; Volant, C.; Anzalone, A.; Arena, N.; Geraci, M.; Giustolisi, F.; Pagano, A.

    2005-05-01

    In nuclear and atomic experiments at high incident ion energies, 20 MeV/ u < E < 100 MeV/ u, the impact of swift heavy ions on thin solid targets is a source of fast electrons. The knowledge of their spatial and kinematical distributions is very useful for experimental nuclear and radiobiological applications as well as testing atomic ionization theories. An overview on the main mechanisms underlying the production of the electrons is given. Some recent results obtained at the Catania LNS superconducting cyclotron, mainly with a 45 MeV/ u58Ni 19+ beam are shown. In particular, the production and the properties of binary encounter-, convoy-, in-flight Auger- and backward emitted electrons are discussed.

  6. Near-earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    DOE PAGESBeta

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R.; Cattell, Cynthia A.; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N.; et al

    2015-08-10

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L~5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ~40 s and a dispersionless injection of electrons up to ~3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front.more » Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.« less

  7. Near-earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    SciTech Connect

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R.; Cattell, Cynthia A.; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N.; Li, Xinlin; Malaspina, David; Blake, J. Bernard; Fennell, Joseph; Claudepierre, Seth; Turner, Drew L.; Reeves, Geoffrey D.; Funsten, Herbert O.; Spence, Harlan E.; Angelopoulos, Vassilis; Fruehauff, Dennis; Chen, Lunjin; Thaller, Scott; Breneman, Aaron; Tang, Xiangwei

    2015-08-10

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L~5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ~40 s and a dispersionless injection of electrons up to ~3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.

  8. Near-Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R.; Cattell, Cynthia A.; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N.; Li, Xinlin; Malaspina, David; Blake, J. Bernard; Fennell, Joseph; Claudepierre, Seth; Turner, Drew L.; Reeves, Geoffrey D.; Funsten, Herbert O.; Spence, Harlan E.; Angelopoulos, Vassilis; Fruehauff, Dennis; Chen, Lunjin; Thaller, Scott; Breneman, Aaron; Tang, Xiangwei

    2015-08-01

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L ˜ 5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ˜40 s and a dispersionless injection of electrons up to ˜3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.

  9. 1 MeV, 10 kW DC electron accelerator for industrial applications

    NASA Astrophysics Data System (ADS)

    Nayak, B.; Acharya, S.; Bhattacharjee, D.; Bakhtsingh, R. I.; Rajan, R.; Sharma, D. K.; Dewangan, S.; Sharma, V.; Patel, R.; Tiwari, R.; Benarjee, S.; Srivastava, S. K.

    2016-03-01

    Several modern applications of radiation processing like medical sterilization, rubber vulcanization, polymerization, cross-linking and pollution control from thermal power stations etc. require D.C. electron accelerators of energy ranging from a few hundred keVs to few MeVs and power from a few kilowatts to hundreds of kilowatts. To match these requirements, a 3 MeV, 30 kW DC electron linac has been developed at BARC, Mumbai and current operational experience of 1 MeV, 10 kW beam power will be described in this paper. The LINAC composed mainly of Electron Gun, Accelerating Tubes, Magnets, High Voltage source and provides 10 kW beam power at the Ti beam window stably after the scanning section. The control of the LINAC is fully automated. Here Beam Optics study is carried out to reach the preferential parameters of Accelerating as well as optical elements. Beam trials have been conducted to find out the suitable operation parameters of the system.

  10. Simulation of electron behavior in PIG ion source for 9 MeV cyclotron

    NASA Astrophysics Data System (ADS)

    J. Mu, X.; Ghergherehchi, M.; H. Yeon, Y.; W. Kim, J.; S. Chai, J.

    2014-12-01

    In this paper, we focus on a PIG source for producing intense H-ions inside a 9 MeV cyclotron. The properties of the PIG ion source were simulated for a variety of electric field distributions and magnetic field strengths using a CST particle studio. After analyzing the secondary electron emission (SEE) as a function of both magnetic and electric field strengths, we found that for the modeled PIG geometry, a magnetic field strength of 0.2 T provided the best results in terms of the number of secondary electrons. Furthermore, at 0.2 T, the number of secondary electrons proved to be greatest regardless of the cathode potential. Also, the modified PIG ion source with quartz insulation tubes was tested in a KIRAMS-13 cyclotron by varying the gas flow rate and arc current, respectively. The capacity of the designed ion source was also demonstrated by producing plasma inside the constructed 9 MeV cyclotron. As a result, the ion source is verified as being capable of producing an intense H- beam and high ion beam current for the desired 9 MeV cyclotron. The simulation results provide experimental constraints for optimizing the strength of the plasma and final ion beam current at a target inside a cyclotron.

  11. "Cabinet-Safe" Study of 1-8 MeV Electron Accelerators

    SciTech Connect

    Wells, Douglas P; Jones, James Litton; Yoon, Woo Yong; Harmon, Frank Gamble

    2001-05-01

    The development of "cabinet-safe" accelerator technology for ˜1–8 MeV electron LINACs would remove the only major barrier to large-scale "field" applications of these accelerators. These applications range from non-destructive evaluation and assay to radiolytic degradation of hazardous waste. All field applications require large forward dose and very little lateral dose. We investigated the origin, energy, and angular distribution of unwanted lateral radiation dose from two different electron LINACS at three energies. We report on the contributions of various beam parameters to unwanted radiation dose and propose methods to control key beam parameters that significantly contribute to these doses.

  12. ``Cabinet-safe'' study of 1-8MeV electron accelerators

    NASA Astrophysics Data System (ADS)

    Wells, D. P.; Jones, J. L.; Yoon, W. Y.; Harmon, F.

    2001-05-01

    The development of "cabinet-safe" accelerator technology for ≈1-8 MeV electron LINACs would remove the only major barrier to large-scale "field" applications of these accelerators. These applications range from non-destructive evaluation and assay to radiolytic degradation of hazardous waste. All field applications require large forward dose and very little lateral dose. We investigated the origin, energy, and angular distribution of unwanted lateral radiation dose from two different electron LINACS at three energies. We report on the contributions of various beam parameters to unwanted radiation dose and propose methods to control key beam parameters that significantly contribute to these doses.

  13. X-ray observations of MeV electron precipitation with a balloon-borne germanium spectrometer

    NASA Astrophysics Data System (ADS)

    Millan, R. M.; Lin, R. P.; Smith, D. M.; Lorentzen, K. R.; McCarthy, M. P.

    2002-12-01

    The high-resolution germanium detector aboard the MAXIS (MeV Auroral X-ray Imaging and Spectroscopy) balloon payload detected nine X-ray bursts with significant flux extending above 0.5 MeV during an 18 day flight over Antarctica. These minutes-to-hours-long events are characterized by an extremely flat spectrum (~E-2) similar to the first MeV event discovered in 1996, indicating that the bulk of parent precipitating electrons is at relativistic energies. The MeV bursts were detected between magnetic latitudes 58°-68° (L-values of 3.8-6.7) but only in the late afternoon/dusk sectors (14:30-00:00 MLT), suggesting scattering by EMIC (electromagnetic ion cyclotron) waves as a precipitation mechanism. We estimate the average flux of precipitating E >= 0.5 MeV electrons to be ~360 cm-2s-1, corresponding to about 5 × 1025 such electrons precipitated during the eight days at L = 3.8-6.7, compared to ~2 × 1025 trapped 0.5-3.6 MeV electrons estimated from dosimeter measurements on a GPS spacecraft. These observations show that MeV electron precipitation events are a primary loss mechanism for outer zone relativistic electrons.

  14. Comparing Solar-Flare Acceleration of >-20 MeV Protons and Electrons Above Various Energies

    NASA Technical Reports Server (NTRS)

    Shih, Albert Y.

    2010-01-01

    A large fraction (up to tens of percent) of the energy released in solar flares goes into accelerated ions and electrons, and studies indicate that these two populations have comparable energy content. RHESSI observations have shown a striking close linear correlation between the 2.223 MeV neutron-capture gamma-ray line and electron bremsstrahlung emission >300 keV, indicating that the flare acceleration of >^20 MeV protons and >300 keV electrons is roughly proportional over >3 orders of magnitude in fluence. We show that the correlations of neutron-capture line fluence with GOES class or with bremsstrahlung emission at lower energies show deviations from proportionality, primarily for flares with lower fluences. From analyzing thirteen flares, we demonstrate that there appear to be two classes of flares with high-energy acceleration: flares that exhibit only proportional acceleration of ions and electrons down to 50 keV and flares that have an additional soft, low-energy bremsstrahlung component, suggesting two separate populations of accelerated electrons. We use RHESSI spectroscopy and imaging to investigate a number of these flares in detail.

  15. Dosimetric shield evaluation with tungsten sheet in 4, 6, and 9MeV electron beams.

    PubMed

    Fujimoto, Takahiro; Monzen, Hajime; Nakata, Manabu; Okada, Takashi; Yano, Shinsuke; Takakura, Toru; Kuwahara, Junichi; Sasaki, Makoto; Higashimura, Kyoji; Hiraoka, Masahiro

    2014-11-01

    In electron radiotherapy, shielding material is required to attenuate beam and scatter. A newly introduced shielding material, tungsten functional paper (TFP), has been anticipated to become a very useful device that is lead-free, light, flexible, and easily processed, containing very fine tungsten powder at as much as 80% by weight. The purpose of this study was to investigate the dosimetric changes due to TFP shielding for electron beams. TFP (thickness 0-15mm) was placed on water or a water-equivalent phantom. Percentage depth ionization and transmission were measured for 4, 6, and 9MeV electron beams. Off-center ratio was also measured using film dosimetry at depth of dose maximum under similar conditions. Then, beam profiles and transmission with two shielding materials, TFP and lead, were evaluated. Reductions of 95% by using TFP at 0.5cm depth occurred at 4, 9, and 15mm with 4, 6, and 9MeV electron beams, respectively. It is found that the dose tend to increase at the field edge shaped with TFP, which might be influenced by the thickness. TFP has several unique features and is very promising as a useful tool for radiation protection for electron beams, among others. PMID:24953537

  16. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; Spence, Harlan E.

    2015-12-01

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. To provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraft were used as the predictors. Model explanatory parameters were selected from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L ≧ 4.8 and L ≧ 5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≦ L ≦ 6, while for the GEO flux prediction, the KP index is better than Dst. A test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.

  17. Attenuation of 10 MeV electron beam energy to achieve low doses does not affect Salmonella spp. inactivation kinetics

    NASA Astrophysics Data System (ADS)

    Hieke, Anne-Sophie Charlotte; Pillai, Suresh D.

    2015-05-01

    The effect of attenuating the energy of a 10 MeV electron beam on Salmonella inactivation kinetics was investigated. No statistically significant differences were observed between the D10 values of either Salmonella 4,[5],12:i:- or a Salmonella cocktail (S. 4,[5],12:i:-, Salmonella Heidelberg, Salmonella Newport, Salmonella Typhimurium, Salmonella) when irradiated with either a non-attenuated 10 MeV eBeam or an attenuated 10 MeV eBeam (~2.9±0.22 MeV). The results show that attenuating the energy of a 10 MeV eBeam to achieve low doses does not affect the inactivation kinetics of Salmonella spp. when compared to direct 10 MeV eBeam irradiation.

  18. Calibration of imaging plates to electrons between 40 and 180 MeV.

    PubMed

    Rabhi, N; Bohacek, K; Batani, D; Boutoux, G; Ducret, J-E; Guillaume, E; Jakubowska, K; Thaury, C; Thfoin, I

    2016-05-01

    This paper presents the response calibration of Imaging Plates (IPs) for electrons in the 40-180 MeV range using laser-accelerated electrons at Laboratoire d'Optique Appliquée (LOA), Palaiseau, France. In the calibration process, the energy spectrum and charge of electron beams are measured by an independent system composed of a magnetic spectrometer and a Lanex scintillator screen used as a calibrated reference detector. It is possible to insert IPs of different types or stacks of IPs in this spectrometer in order to detect dispersed electrons simultaneously. The response values are inferred from the signal on the IPs, due to an appropriate charge calibration of the reference detector. The effect of thin layers of tungsten in front and/or behind IPs is studied in detail. GEANT4 simulations are used in order to analyze our measurements. PMID:27250413

  19. Effects of 1- and 2-MeV electrons on photomultiplier tubes

    NASA Technical Reports Server (NTRS)

    Beatty, M. E., III; Debnam, W. J., Jr.; Meredith, B. D.

    1976-01-01

    Various types of photomultiplier tubes useful for space applications were irradiated with 1- and 2-MeV electrons at Van Allen radiation belt fluxes of 100,000 to 10 millions electrons/sq cm-sec. The increase in the dark current due to electron irradiation was observed at various bias voltages under worst-case conditions (no shielding). Results were presented in the form of dark current plotted against electron flux. All the tubes tested showed extremely large increases in dark current. Tube types 541A, 6217, 6199, and 6903 exhibited the largest increases under irradiation, whereas type 1P22 was affected the least. All the damage observed was transient. The luminescence produced in the optical window probably accounts for a large part of the dark-current increases, but there were some effects possibly due to direct irradiation of the photocathode and dynode chain.

  20. Lateral propagation of MeV electrons generated by femtosecond laser irradiation

    SciTech Connect

    Seely, J. F.; Szabo, C. I.; Audebert, P.; Brambrink, E.; Tabakhoff, E.; Hudson, L. T.

    2010-02-15

    The propagation of MeV electrons generated by intense (approx =10{sup 20} W/cm{sup 2}) femtosecond laser irradiation, in the lateral direction perpendicular to the incident laser beam, was studied using targets consisting of irradiated metal wires and neighboring spectator wires embedded in electrically conductive (aluminum) or resistive (Teflon) substrates. The K shell spectra in the energy range 40-60 keV from wires of Gd, Dy, Hf, and W were recorded by a transmission crystal spectrometer. The spectra were produced by 1s electron ionization in the irradiated wire and by energetic electron propagation through the substrate material to the spectator wire of a different metal. The electron range and energy were determined from the relative K shell emissions from the irradiated and spectator wires separated by varying substrate lateral distances of up to 1 mm. It was found that electron propagation through Teflon was inhibited, compared to aluminum, implying a relatively weak return current and incomplete space-charge neutralization. The energetic electron propagation in the direction parallel to the electric field of the laser beam was larger than perpendicular to the electric field. Energetic electron production was lower when directly irradiating aluminum or Teflon compared to irradiating the heavy metal wires. These experiments are important for the determination of the energetic electron production mechanism and for understanding lateral electron propagation that can be detrimental to fast-ignition fusion and hard x-ray backlighter radiography.

  1. Optimization of intensity-modulated very high energy (50-250 MeV) electron therapy

    NASA Astrophysics Data System (ADS)

    Yeboah, C.; Sandison, G. A.; Moskvin, V.

    2002-04-01

    This work evaluates the potential of very high energy (50-250 MeV) electron beams for dose conformation and identifies those variables that influence optimized dose distributions for this modality. Intensity-modulated plans for a prostate cancer model were optimized as a function of the importance factors, beam energy and number of energy bins, number of beams, and the beam orientations. A trial-and-error-derived constellation of importance factors for target and sensitive structures to achieve good conformal dose distributions was 500, 50, 10 and 1 for the target, rectum, bladder and normal tissues respectively. Electron energies greater than 100 MeV were found to be desirable for intensity-modulated very high energy electron therapy (VHEET) of prostate cancer. Plans generated for lower energy beams had relatively poor conformal dose distributions about the target region and delivered high doses to sensitive structures. Fixed angle beam treatments utilizing a large number of fields in the range 9-21 provided acceptable plans. Using more than 21 beams at fixed gantry angles had an insignificant effect on target coverage, but resulted in an increased dose to sensitive structures and an increased normal tissue integral dose. Minor improvements in VHEET plans utilizing a `small' number (=<9) of beams may be achieved if, in addition to intensity modulation, energy modulation is implemented using a small number (=<3) of beam energies separated by 50 to 100 MeV. Rotation therapy provided better target dose homogeneity but unfortunately resulted in increased rectal dose, bladder dose and normal tissue integral dose relative to the 21-field fixed angle treatment plan. Modulation of the beam energy for rotation therapy had no beneficial consequences on the optimized dose distributions. Lastly, selection of beam orientations influenced the optimized treatment plan even when a large number of beams (approximately 15) were employed.

  2. Toward 10 meV electron energy-loss spectroscopy resolution for plasmonics.

    PubMed

    Bellido, Edson P; Rossouw, David; Botton, Gianluigi A

    2014-06-01

    Energy resolution is one of the most important parameters in electron energy-loss spectroscopy. This is especially true for measurement of surface plasmon resonances, where high-energy resolution is crucial for resolving individual resonance peaks, in particular close to the zero-loss peak. In this work, we improve the energy resolution of electron energy-loss spectra of surface plasmon resonances, acquired with a monochromated beam in a scanning transmission electron microscope, by the use of the Richardson-Lucy deconvolution algorithm. We test the performance of the algorithm in a simulated spectrum and then apply it to experimental energy-loss spectra of a lithographically patterned silver nanorod. By reduction of the point spread function of the spectrum, we are able to identify low-energy surface plasmon peaks in spectra, more localized features, and higher contrast in surface plasmon energy-filtered maps. Thanks to the combination of a monochromated beam and the Richardson-Lucy algorithm, we improve the effective resolution down to 30 meV, and evidence of success up to 10 meV resolution for losses below 1 eV. We also propose, implement, and test two methods to limit the number of iterations in the algorithm. The first method is based on noise measurement and analysis, while in the second we monitor the change of slope in the deconvolved spectrum. PMID:24690472

  3. Plasma devices to guide and collimate a high density of MeV electrons.

    PubMed

    Kodama, R; Sentoku, Y; Chen, Z L; Kumar, G R; Hatchett, S P; Toyama, Y; Cowan, T E; Freeman, R R; Fuchs, J; Izawa, Y; Key, M H; Kitagawa, Y; Kondo, K; Matsuoka, T; Nakamura, H; Nakatsutsumi, M; Norreys, P A; Norimatsu, T; Snavely, R A; Stephens, R B; Tampo, M; Tanaka, K A; Yabuuchi, T

    2004-12-23

    The development of ultra-intense lasers has facilitated new studies in laboratory astrophysics and high-density nuclear science, including laser fusion. Such research relies on the efficient generation of enormous numbers of high-energy charged particles. For example, laser-matter interactions at petawatt (10(15) W) power levels can create pulses of MeV electrons with current densities as large as 10(12) A cm(-2). However, the divergence of these particle beams usually reduces the current density to a few times 10(6) A cm(-2) at distances of the order of centimetres from the source. The invention of devices that can direct such intense, pulsed energetic beams will revolutionize their applications. Here we report high-conductivity devices consisting of transient plasmas that increase the energy density of MeV electrons generated in laser-matter interactions by more than one order of magnitude. A plasma fibre created on a hollow-cone target guides and collimates electrons in a manner akin to the control of light by an optical fibre and collimator. Such plasma devices hold promise for applications using high energy-density particles and should trigger growth in charged particle optics. PMID:15616556

  4. Diagnostics for a 1.2 kA, 1 MeV, electron induction injector

    NASA Astrophysics Data System (ADS)

    Houck, T. L.; Anderson, D. E.; Eylon, S.; Henestroza, E.; Lidia, S. M.; Vanecek, D. L.; Westenskow, G. A.; Yu, S. S.

    1998-12-01

    We are constructing a 1.2 kA, 1 MeV, electron induction injector as part of the RTA program, a collaborative effort between LLNL and LBNL to develop relativistic klystrons for Two-Beam Accelerator applications. The RTA injector will also be used in the development of a high-gradient, low-emittance, electron source and beam diagnostics for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility. The electron source will be a 3.5″-diameter, thermionic, flat-surface, m-type cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150 ns flat top (1% energy variation), and a normalized edge emittance of less than 200 π-mm-mr. Precise measurement of the beam parameters is required so that performance of the RTA injector can be confidently scaled to the 4 kA, 3 MeV, and 2-microsecond pulse parameters of the DARHT injector. Planned diagnostics include an isolated cathode with resistive divider for direct measurement of current emission, resistive wall and magnetic probe current monitors for measuring beam current and centroid position, capacitive probes for measuring A-K gap voltage, an energy spectrometer, and a pepperpot emittance diagnostic. Details of the injector, beam line, and diagnostics are presented.

  5. Study of imaging plate detector sensitivity to 5-18 MeV electrons

    SciTech Connect

    Boutoux, G. Rabhi, N.; Batani, D.; Ducret, J.-E.; Binet, A.; Nègre, J.-P.; Reverdin, C.; Thfoin, I.; Jakubowska, K.

    2015-11-15

    Imaging plates (IPs) are commonly used as passive detectors in laser-plasma experiments. We calibrated at the ELSA electron beam facility (CEA DIF) the five different available types of IPs (namely, MS-SR-TR-MP-ND) to electrons from 5 to 18 MeV. In the context of diagnostic development for the PETawatt Aquitaine Laser (PETAL), we investigated the use of stacks of IP in order to increase the detection efficiency and get detection response independent from the neighboring materials such as X-ray shielding and detector supports. We also measured fading functions in the time range from a few minutes up to a few days. Finally, our results are systematically compared to GEANT4 simulations in order to provide a complete study of the IP response to electrons over the energy range relevant for PETAL experiments.

  6. Study of imaging plate detector sensitivity to 5-18 MeV electrons.

    PubMed

    Boutoux, G; Rabhi, N; Batani, D; Binet, A; Ducret, J-E; Jakubowska, K; Nègre, J-P; Reverdin, C; Thfoin, I

    2015-11-01

    Imaging plates (IPs) are commonly used as passive detectors in laser-plasma experiments. We calibrated at the ELSA electron beam facility (CEA DIF) the five different available types of IPs (namely, MS-SR-TR-MP-ND) to electrons from 5 to 18 MeV. In the context of diagnostic development for the PETawatt Aquitaine Laser (PETAL), we investigated the use of stacks of IP in order to increase the detection efficiency and get detection response independent from the neighboring materials such as X-ray shielding and detector supports. We also measured fading functions in the time range from a few minutes up to a few days. Finally, our results are systematically compared to GEANT4 simulations in order to provide a complete study of the IP response to electrons over the energy range relevant for PETAL experiments. PMID:26628126

  7. Scale size of magnetic turbulence in tokamaks probed with 30-MeV electrons

    PubMed

    Entrop; Lopes Cardozo NJ; Jaspers; Finken

    2000-04-17

    Measurements of synchrotron radiation emitted by 30-MeV runaway electrons in the TEXTOR-94 tokamak show that the runaway population decays after switching on neutral beam injection (NBI). The decay starts only with a significant delay, which decreases with increasing NBI heating power. This delay provides direct evidence of the energy dependence of runaway confinement, which is expected if magnetic modes govern the loss of runaways. Application of the theory by Mynick and Strachan [Phys. Fluids 24, 695 (1981)] yields estimates for the "mode width" (delta) of magnetic perturbations: delta<0.5 cm in Ohmic discharges, increasing to delta = 4.4 cm for 0. 6 MW NBI. PMID:11019157

  8. A 2 MeV, 100 mA electron accelerator for a small laboratory environment

    NASA Astrophysics Data System (ADS)

    Clayton, C. E.; Marsh, K. A.

    1993-03-01

    A small, high performance electron linear accelerator is described. It is a modified version of a commercially available portable x-ray source. The 9.3 GHz rf linac and beamline deliver a 3 ns train of approximately 15 ps pulses with a peak current, limited by beam loading of the rf structure, of more than 100 mA and a beam energy of around 2 MeV with a 5% full width at half maximum energy spread. The beam emittance is 6π mm mrad and the final spot size is 250 μm diam for f/10 focusing.

  9. Attainment of a high-quality electron beam for Fermilab's 4.3 MeV cooler

    SciTech Connect

    Shemyakin, A.; Burov, Alexey V.; Carlson, K.; Hu, M.; Kazakevich, G.; Kramper, B.; Kroc, T.; Leibfritz, J.; Nagaitsev, S.; Prost, L.; Pruss, S.; Saewert, G.; Schmidt, C.W.; Seletskiy, S.; Sutherland, M.; Tupikov, V.; Warner, A.; /Fermilab /Novosibirsk, IYF /Rochester U.

    2005-11-01

    The recent demonstration of electron cooling of antiprotons in the Recycler ring required a stable 4.3 MeV electron beam with a DC current of hundreds of mA and an angular spread in the cooling section of a fraction of a mrad. This paper describes the achieved parameters of the Fermilab cooler's electron beam and details of operation.

  10. Attainment of a High-Quality Electron Beam for Fermilab's 4.3 MeV Cooler

    SciTech Connect

    Shemyakin, A.; Burov, A.; Carlson, K.; Hu, M.; Kramper, B.; Kroc, T.; Leibfritz, J.; Nagaitsev, S.; Prost, L.; Pruss, S.; Saewert, G.; Schmidt, C. W.; Sutherland, M.; Tupikov, V.; Warner, A.; Kazakevich, G.; Seletskiy, S.

    2006-03-20

    The recent demonstration of electron cooling of antiprotons in the Recycler ring required a stable 4.3 MeV electron beam with a DC current of hundreds of mA and an angular spread in the cooling section of a fraction of a mrad. This paper describes the achieved parameters of the Fermilab cooler's electron beam and details of operation.

  11. Gas Desorption and Electron Emission from 1 MeV Potassium Iion Bombardment of Stainless Steel

    SciTech Connect

    Molvik, A; Covo, M K; Bieniosek, F; Prost, L; Seidl, P; Baca, D; Coorey, A; Sakumi, A

    2004-03-25

    Gas desorption and electron emission coefficients were measured for 1 MeV potassium ions incident on stainless steel at grazing angles (between 80 and 88 degrees from normal incidence) using a new gas-electron source diagnostic (GESD). Issues addressed in design and commissioning of the GESD include effects from backscattering of ions at the surface, space-charge limited emission current, and reproducibility of desorption measurements. We find that electron emission coefficients {gamma}{sub e} scale as 1/cos({theta}) up to angles of 86 degrees, where {gamma}{sub e} = 90. Nearer grazing incidence, {gamma}{sub e} is reduced below the 1/cos({theta}) scaling by nuclear scattering of ions through large angles, reaching {gamma}{sub e} = 135 at 88 degrees. Electrons were emitted with a measured temperature of {approx}30 eV. Gas desorption coefficients {gamma}{sub 0} were much larger, of order {gamma}{sub 0} = 10{sub 4}. They also varied with angle, but much more slowly than 1/cos({theta}). From this we conclude that the desorption was not entirely from adsorbed layers of gas on the surface. Two mitigation techniques were investigated: rough surfaces reduced electron emission by a factor of ten and gas desorption by a factor of two; a mild bake to {approx}220 degrees had no effect on electron emission, but decreased gas desorption by 15% near grazing incidence. We propose that gas desorption is due to electronic sputtering.

  12. Gas Desorption and Electron Emission from 1 MeV Potassium Ion Bombardment of Stainless Steel

    SciTech Connect

    Molvik, A W; Covo, M K; Bieniosek, F M; Prost, L; Seidl, P A; Baca, D; Coorey, A; Sakumi, A

    2004-07-19

    Gas desorption and electron emission coefficients were measured for 1 MeV potassium ions incident on stainless steel at grazing angles (between 80 and 88 from normal incidence) using a new gas-electron source diagnostic (GESD). Issues addressed in design and commissioning of the GESD include effects from backscattering of ions at the surface, space-charge limited emission current, and reproducibility of desorption measurements. We find that electron emission coefficients {gamma}{sub e} scale as 1/cos({theta}) up to angles of 86, where {gamma}{sub e} = 90. Nearer grazing incidence, {gamma}{sub e} is reduced below the 1/cos({theta}) scaling by nuclear scattering of ions through large angles, reaching {gamma}{sub e} = 135 at 88. Electrons were emitted with a measured temperature of {approx}30 eV. Gas desorption coefficients {gamma}{sub sigma} were much larger, of order {gamma}{sub sigma} = 104. They also varied with angle, but much more slowly than 1/cos({theta}). From this we conclude that the desorption was not entirely from adsorbed layers of gas on the surface. Two mitigation techniques were investigated: rough surfaces reduced electron emission by a factor of ten and gas desorption by a factor of two; a mild bake to 230 had no effect on electron emission, but decreased gas desorption by 15% near grazing incidence. We propose that gas desorption is due to electronic sputtering.

  13. Multiple Balloon Campaign (MINIS) to Study MeV Electron Precipitation

    NASA Astrophysics Data System (ADS)

    Sample, J. G.; Smith, D. M.; Parks, G.; Holzworth, R.; Bering, E. A.; McCarthy, M.; Millan, R.; Kokorowski, M.; Reddell, B.; Huss, L.; Lay, E.; Bale, S.; Delory, G.; O'Brien, P.; Blake, J.; Lin, R. P.; Hughes, A. R.; Stoker, P.; Moraal, H.

    2003-12-01

    A unique new Antarctic multiple balloon campaign MINIS (MINIature Spectrometer) is set for launch in December `04. Using small (7000m3) hand-launched balloons, four identical payloads will carry a suite of instruments principally designed to study the precipitation of relativistic (MeV) electrons from the radiation belts. The payloads will have the opportunity and the capability to study rare, recently discovered precipitation events that are short-lived and precipitate only the highest-energy electrons, (Foat et al. 1998, GRL 25, no. 22; Millan et al. 2002, GRL 29, no. 24). Understanding the loss mechanisms for the MeV electron radiation belt population is interesting in its own right, but may also help us to understand the origin and acceleration of these particles and better protect satellites from radiation damage. MeV electron precipitation events may even influence ozone depletion at mid to high latitudes, depending on the downward transport of odd nitrogen compounds. Each MINIS payload will include a NaI scintillator for the detection of bremsstrahlung X-rays as well as instruments to detect electromagnetic fields and waves which will help indicate the cause of a given precipitation event. The payloads will be launched successively in December 2004 from the South African National Antarctic Expedition IV (SANAE) base (72S,2E) such that they will be able to simultaneously study temporal and spatial variations in the precipitation of electrons in both the bounce-loss and drift-loss populations at L-values between 4 and 6. Having four balloons at different positions will also allow us to study magnetic local time effects in the precipitation processes and will also provide a new platform for studying substorm evolution in conjunction with existing instruments on the ground and in space. In preparation for the December '04 campaign from SANAE, a single balloon will be launched in December '03 from McMurdo Station, Antarctica in order to test the payload

  14. Vacuum system of the 3MeV industrial electron beam accelerator

    NASA Astrophysics Data System (ADS)

    Jayaprakash, D.; Mishra, R. L.; Ghodke, S. R.; kumar, M.; kumar, M.; Nanu, K.; Mittal, K. C., Dr

    2008-05-01

    One DC Accelerator, for electron beam of 3 MeV energy and 10 mA beam current, to derive 30 KW beam power for Industrial applications is nearing completion at Electron Beam Centre, Kharghar, Navi Mumbai. Beam-line of the accelerator is six meters long, consists of electron gun at top, followed by the accelerating column and finally the scan horn. Electron gun and the accelerating column is exposed to SF6 gas at six atmospheres. Area exposed to the vacuum is 65,000 sq: cm, and includes a volume of 200 litres. Vacuum of the order of 1×10-7mbar is desired. To ensure a good vacuum gradient, distributive pumping is implemented. Electron beam is scanned to a size of 5cm × 120cm, to get a useful beam coverage, for industrial radiation applications. The beam is extracted through a window of Titanium foil of 50μm thickness. A safety interlock, to protect the electron gun, accelerating column and sputter ion pumps, in case of a foil rupture, is incorporated. Foil change can be done without disturbing the vacuum in the other zones. System will be integrated to a master control system to take care of the various safety aspects, and to make it operator friendly.

  15. Optimization of Electron Beam Transport for a 3-MeV DC Accelerator

    NASA Astrophysics Data System (ADS)

    Baruah, S.; Bhattacharjee, D.; Tiwari, R.; Sahu, G. K.; Thakur, K. B.; Mittal, K. C.; Gantayet, L. M.

    2012-11-01

    Transport of a low-current-density electron beam is simulated for an electrostatic accelerator system. Representative charged particles are uniformly assigned for emission from a circular indirectly-heated cathode of an axial electron gun. The beam is accelerated stepwise up to energy of 1 MeV electrostatically in a length-span of ~3 m using multiple accelerating electrodes in a column of ten tubes. The simulation is done under relativistic condition and the effect of the magnetic field induced by the cathode-heating filament current is taken into account. The beam diameter is tracked at different axial locations for various settings of the electrode potentials. Attempts have been made to examine and explain data on beam transport efficiency obtained from experimental observations.

  16. The EB10 10 MeV, 30 kW electron irradiation facility

    NASA Astrophysics Data System (ADS)

    Karlsson, Mikael

    An irradiation plant including a 10 MeV, 30 kW electron accelerator is described. The accelerator is a four stage linac of standing wave type. Using a 90 degrees bending magnet for energy definition it irradiates boxes on a conveyor from below. The system design emphasizes the necessity for documentation of absorbed dose for each irradiated box by continuous monitoring and recording of the beam process parameters. This makes the system well suitable for irradiation sterilization. A magnet at the exit window corrects for the divergent field introduced by the scanning magnet, giving vertical electrons over the full scanning width. This feature provides more uniform irradiation and it also increases the efficiency of the unit by almost 20 %.

  17. Capacitance and conductance studies on silicon solar cells subjected to 8 MeV electron irradiations

    NASA Astrophysics Data System (ADS)

    Sathyanarayana Bhat, P.; Rao, Asha; Sanjeev, Ganesh; Usha, G.; Priya, G. Krishna; Sankaran, M.; Puthanveettil, Suresh E.

    2015-06-01

    The space grade silicon solar cells were irradiated with 8 MeV electrons with doses ranging from 5-100 k Gy. Capacitance and conductance measurements were carried out in order to investigate the anomalous degradation of the cells in the radiation harsh environments and the results are presented in this paper. Detailed and systematic analysis of the frequency-dependent capacitance and conductance measurements were performed to extract the information about the interface trap states. The small increase in density of interface states was observed from the conductance-frequency measurements. The reduction in carrier concentration upon electron irradiation is due to the trapping of charge carriers by the radiation induced trap centres. The Drive Level Capacitance Profiling (DLCP) technique has been applied to study the properties of defects in silicon solar cells. A small variation in responding state densities with measuring frequency was observed and the defect densities are in the range 1015 -1016 cm-3.

  18. MeV electron acceleration by sub-terawatt laser pulses in near critical density plasmas

    NASA Astrophysics Data System (ADS)

    Goers, Andy; Hine, George; Feder, Linus; Miao, Bo; Salehi, Fatholah; Milchberg, Howard

    2015-11-01

    We demonstrate laser-plasma acceleration of high charge electron beams to the 10 MeV scale using ultrashort laser pulses with as little energy as 10 mJ. This result is made possible by an extremely dense and thin hydrogen gas jet where even sub-terawatt laser pulses are well above the critical power for relativistic self-focusing, and the 10 mJ pulses can drive a self-modulated wakefield accelerator. Total charge up to 0.5 nC is measured for energies >1 MeV. Acceleration is correlated to the presence of an intense, coherent, broadband light flash, associated with wavebreaking, which can radiate more than 3% of the laser energy in a sub-femtosecond bandwidth consistent with half-cycle optical emission. Our results enable truly portable applications of laser-driven acceleration, such as low dose radiography, ultrafast probing of matter, and isotope production. This work supported by DTRA and the US Department of Energy.

  19. Observational Search for >10 MeV Electrons in the Inner Magnetosphere Using the Van Allen Probes Relativistic Proton Spectrometer

    NASA Astrophysics Data System (ADS)

    Mazur, J. E.; Looper, M. D.; O'Brien, T. P., III; Blake, J. B.

    2015-12-01

    Any detection of ultra-relativistic electrons (>10 MeV) trapped in the inner magnetosphere is potentially a sensitive indicator of a unique particle acceleration process or of a unique particle source. The 24 March 1991 shock injection of >15 MeV electrons is a classic example of the former, while the latter includes measurements in low Earth orbit of >100 MeV electrons and positrons from cosmic ray interactions with the atmosphere. In this paper we use new instrumentation on the Van Allen Probes to survey the inner magnetosphere for signatures of ultra-relativistic electrons. The Relativistic Proton Spectrometer, designed primarily for spectroscopy of 60 to 2000 MeV protons in the inner belt, nonetheless is capable of detecting minimum-ionizing electrons in a silicon detector stack. More critical to this survey is the instrument's Cherenkov radiator subsystem whose response to incident electrons ranges from a threshold near 10 MeV and reaches light saturation above 50 MeV. Together with the silicon detector system we are able to explore an energy range that has not been routinely studied in the context of the Earth's magnetosphere. We will report on quiet-time and storm-time signatures in regions of the inner magnetosphere that heretofore have not been explored with an orbit like that of Van Allen Probes. We will also quantitatively compare our electron energy spectra, or flux limits, with other measurements from Van Allen Probes and prior glimpses of high-energy electrons from low Earth orbit.

  20. X-ray observations of MeV electron precipitation with a balloon-borne germanium spectrometer

    NASA Astrophysics Data System (ADS)

    Millan, Robyn Margaret

    The MAXIS (MeV Auroral X-ray Imaging and Spectroscopy) balloon payload was launched on a long duration balloon from McMurdo, Antarctica on Jan. 12, 2000. The high spectral resolution germanium spectrometer aboard MAXIS detected nine X-ray bursts with significant flux extending above 0.5 MeV during the 18 day flight. The X-rays are bremsstrahlung produced by precipitating electrons and the events are characterized by an extremely flat X-ray spectrum (˜E-2) similar to the first MeV event discovered in 1996, indicating relativistic parent electrons. The bursts were detected between magnetic latitudes 58°--68° (IGRF L-values of 3.8--6.7) with durations varying from several minutes to several hours and occurred only in the late afternoon/dusk sectors (14:30--00:00 MLT) while softer precipitation was detected at all magnetic local times. In addition, the MeV events were associated with substorm activity and several events showed Ultra Low Frequency (mHz) modulation of the X-ray count rate. Spacecraft and ground-based observations indicate the presence of ULF wave activity near the time and location of the events which may be causing the modulation by some mechanism that is not understood. The MeV events are well modeled by a very flat exponential precipitating electron distribution and the average flux of precipitating electrons with E ≥ 0.5 MeV is estimated to be ˜360 cm-2 s-1. This corresponds to about 5 x 1025 precipitated electrons in this latitude range during the eight day observing interval compared to ˜2 x 10 25 trapped 0.5--3.6 MeV electrons estimated using GPS electron measurements. The MAXIS observations indicate that these electron precipitation events are common and may be the primary loss mechanism for outer zone relativistic electrons. Individual events were also compared with measurements of the trapped electrons from which it is estimated that only a few percent of the loss cone is being filled by the mechanism acting to precipitate the particles

  1. Accurate measurements of the collision stopping powers for 5 to 30 MeV electrons

    NASA Astrophysics Data System (ADS)

    MacPherson, Miller Shawn

    Accurate knowledge of electron stopping powers is crucial for accurate radiation dosimetry and radiation transport calculations. Current values for stopping powers are based on a theoretical model, with estimated uncertainties of 0.5-1% (1σ) for electron energies greater than 100 keV. This work presents the first measurements of electron collision stopping powers capable of testing the theoretical values within these stated uncertainties. A large NaI spectrometer was used to measure the change in electron energy when an absorbing disk of known thickness was placed in an electron beam. Monte Carlo simulations of the experiment were performed to account for the effects of surrounding materials. Energy differences between the calculated and measured spectra were used to determine corrections to the soft collision component of the theoretical stopping powers employed by the Monte Carlo simulations. Four different elemental materials were studied: Be, Al, Cu, and Ta. This provided a wide range of atomic numbers and densities over which to test the theory. In addition, stopping powers were measured for graphite (both standard and pyrolytic), A-150 tissue equivalent plastic, C-552 air equivalent plastic, and water. The incident electron energies ranged from 5 to 30 MeV. Generally, the measured stopping powers agree with the theoretical values within the experimental uncertainties, which range from 0.4% to 0.7% (1σ). Aluminum, however, exhibits a 0.7% discrepancy at higher electron energies. Furthermore, these measurements have established that the grain density stopping power is appropriate for graphite, contrary to the recommendations of ICRU Report 37. This removes a 0.2% uncertainty in air kerma calibrations, and impacts on dosimetric quantities determined via graphite calorimetry, such as ɛG for Fricke dosimetry and (W/ e)air for ion chamber measurements.

  2. Near realtime forecasting of MeV protons on the basis of sub relativistic electrons

    NASA Astrophysics Data System (ADS)

    Labrenz, Johannes; Heber, Bernd; Kuehl, Patrick; Sarlanis, Christos; Malandraki, Olga; Posner, Arik

    2016-04-01

    A major impact on human and robotic space exploration activities is the sudden and prompt occurrence of solar energetic ion events. In order to provide up to an hour warning before these particles arrive at Earth, relativistic electron and below 50 MeV proton data from the Electron Proton Helium Instrument (EPHIN) on SOHO were used to implement the 'Relativistic Electron Alert System for Exploration (REleASE)'. It has been demonstrated that the analysis of relativistic electron time profiles provides a low miss and false alarm rate. High Energy Solar Particle Events foRecastIng and Analysis (HESPERIA) is a project funded within the European Union's Horizon 2020 research and innovation programme (PROTEC-1-2014 Call: Space Weather). Within this project the REleASE forecasting scheme was rewritten in the open access programming language PYTHON and will be made public. As a next step, we have analyzed the possibility to also use, along with relativistic electrons (v > 0.9 c) provided by SOHO, near-relativistic (v <0.8 c) electron measurements from other instruments like the Electron Proton Alpha Monitor (EPAM) aboard the Advanced Composition Explorer (ACE). This would prove to be particularly useful during periods that SOHO does not provide continuous near real-time data. We show that the ACE/EPAM observations can be adapted to the REleASE forecasting scheme to provide reliable SEP forecasts. A comparison of measured and forecast proton intensities by SOHO/EPHIN and ACE/EPAM will be presented. In addition we investigated the false alarm rate and detection probability of solar ion events. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324.

  3. Stochastic spatial energy deposition profiles for MeV protons and keV electrons

    NASA Astrophysics Data System (ADS)

    Udalagama, C.; Bettiol, A. A.; Watt, F.

    2009-12-01

    With the rapid advances being made in novel high-energy ion-beam techniques such as proton beam writing, single-ion-event effects, ion-beam-radiation therapy, ion-induced fluorescence imaging, proton/ion microscopy, and ion-induced electron imaging, it is becoming increasingly important to understand the spatial energy-deposition profiles of energetic ions as they penetrate matter. In this work we present the results of comprehensive yet straightforward event-by-event Monte Carlo calculations that simulate ion/electron propagation and secondary electron ( δ ray) generation to yield spatial energy-deposition data. These calculations combine SRIM/TRIM features, EEDL97 data and volume-plasmon-localization models with a modified version of one of the newer δ ray generation models, namely, the Hansen-Kocbach-Stolterfoht. The development of the computer code DEEP (deposition of energy due to electrons and protons) offers a unique means of studying the energy-deposition/redistribution problem while still retaining the important stochastic nature inherent in these processes which cannot be achieved with analytical modeling. As an example of an application of DEEP we present results that compare the energy-deposition profiles of primary MeV protons and primary keV electrons in polymethymethacrylate. Such data are important when comparing proximity effects in the direct write lithography processes of proton-beam writing and electron-beam writing. Our calculations demonstrate that protons are able to maintain highly compact spatial energy-deposition profiles compared with electrons.

  4. Bunch evolution study in optimization of MeV ultrafast electron diffraction

    NASA Astrophysics Data System (ADS)

    Lu, Xian-Hai; Du, Ying-Chao; Huang, Wen-Hui; Tang, Chuan-Xiang

    2014-12-01

    Megaelectronvolt ultrafast electron diffraction (UED) is a promising detection tool for ultrafast processes. The quality of diffraction image is determined by the transverse evolution of the probe bunch. In this paper, we study the contributing terms of the emittance and space charge effects to the bunch evolution in the MeV UED scheme, employing a mean-field model with an ellipsoidal distribution as well as particle tracking simulation. The small transverse dimension of the drive laser is found to be critical to improve the reciprocal resolution, exploiting both smaller emittance and larger transverse bunch size before the solenoid. The degradation of the reciprocal spatial resolution caused by the space charge effects should be carefully controlled.

  5. Thermoluminescence response of flat optical fiber subjected to 9 MeV electron irradiations

    NASA Astrophysics Data System (ADS)

    Hashim, S.; Omar, S. S. Che; Ibrahim, S. A.; Hassan, W. M. S. Wan; Ung, N. M.; Mahdiraji, G. A.; Bradley, D. A.; Alzimami, K.

    2015-01-01

    We describe the efforts of finding a new thermoluminescent (TL) media using pure silica flat optical fiber (FF). The present study investigates the dose response, sensitivity, minimum detectable dose and glow curve of FF subjected to 9 MeV electron irradiations with various dose ranges from 0 Gy to 2.5 Gy. The above-mentioned TL properties of the FF are compared with commercially available TLD-100 rods. The TL measurements of the TL media exhibit a linear dose response over the delivered dose using a linear accelerator. We found that the sensitivity of TLD-100 is markedly 6 times greater than that of FF optical fiber. The minimum detectable dose was found to be 0.09 mGy for TLD-100 and 8.22 mGy for FF. Our work may contribute towards the development of a new dosimeter for personal monitoring purposes.

  6. Effect of 1 MeV electrons on ceria-doped solar cell cover glass

    NASA Technical Reports Server (NTRS)

    Haynes, G. A.

    1973-01-01

    The effect of 1 MeV electrons on the transmission properties of 1.5-percent ceria-doped solar cell cover glass was studied. Samples of doped and undoped cover glass and synthetic fused silica were irradiated with a total integrated flux of 10 to the 15th power e/sq cm. Wideband transmission and spectral transmission measurements were made before and after irradiation. The results indicate that 1.5-percent ceria-doped cover glass is much less sensitive to radiation induced discoloration than undoped cover glass. Consequently, the glass is comparable to synthetic fused silica when used as a radiation resistant solar cell cover for many space missions.

  7. Van Allen Probe Observations: Near-Earth injections of Mev Electrons Associated with Intense Substorm Electric Fields

    NASA Astrophysics Data System (ADS)

    Dai, L.; Wygant, J. R.; Bonnell, J. W.; Cattell, C. A.; Kletzing, C.; Baker, D. N.; Li, X.; Malaspina, D.; Blake, J. B.; Fennell, J.; Claudepierre, S. G.; Takahashi, K.; Funsten, H. O.; Reeves, G. D.; Spence, H. E.; Angelopoulos, V.; Glassmeier, K. H.; Turner, D. L.; Thaller, S. A.; Breneman, A. W.; Kersten, K.; Tang, X.; Tao, X.

    2014-12-01

    With their unique orbit, the Van Allen Probes (RBSP) spacecraft are well suited to investigate near-Earth substorm injections that penetrate into the heart of outer radiation belts. Substorms are generally conceived to inject 10s-100s keV electrons but intense substorm electric fields have been shown capable of injecting ~MeV electrons as well at the geosynchronous altitude. An intriguing question is whether such MeV electron injections can penetrate to lower L shells and directly contribute to the relativistic electron population of the outer radiation belt. In this talk, we present RBSP observations of near-Earth substorm injection of MeV relativistic particles and associated intense dipolarization electric field at L ~5.5. The substorm injection occurred during a moderate storm (DST~-30 to -20) with steady solar wind conditions. RBSP-A observed dispersionless injection of electrons from 10s keV up to 3 MeV in the pre-mid night sector (MLT=22UT). The injection was associated with unusually large (60mV/m) dipolarization electric fields that lasted 1 minute. At about the same time, THEMIS-D observed energy-dispersive injection of electrons at energies as high as at least 720keV at L~6.8 in the pre-dawn sector. Injection of energetic protons (~1MeV) and proton drift echos were observed at RBSP-A as well. RBSP-A observed a broad spectrum of nonlinear electric field structures but no whistler waves at the injection. The properties of the observed dipolarization electric field constrain the acceleration mechanism responsible for the MeV electron injection. We will discuss the implications of these observations on the direct impact of substorms on the outer radiation belt.

  8. The Rhodotron, a new 10 MeV, 100 kW, cw metric wave electron accelerator

    NASA Astrophysics Data System (ADS)

    Jongen, Y.; Abs, M.; Genin, F.; Nguyen, A.; Capdevila, J. M.; Defrise, D.

    1993-06-01

    New applications for high energy, high current electron beam processing are continually expanding. Today, however, 10 MeV rf electron linacs are frequently limited to an average beam power of only 20 or 30 kW. To achieve higher beam power, CW operation and the use of lower frequencies are necessary. In the last years, the principle for a new kind of electron accelerator was developed by the Atomic Energy Agency (CEA) in France. This accelerator is based on the principle of recirculating a beam throughout a single coaxial cavity resonating in metric waves. A 3.3 MeV, 4 mA prototype has been built and successfully tested. The industrial accelerator developed by IBA in collaboration with the CEA is a 10 MeV, 100 kW beam power unit with an additional beam exit at 5 MeV. The cavity, made of copper-plated steel, will resonate at 107.5 MHz. A rf power of 100 kW is needed to produce an electric field allowing an energy gain of 1 MeV per crossing. In addition, 100 kW of power is needed for acceleration. The 200 kW output amplifier uses a 100 kW plate dissipation tetrode (TH 681 from Thomson-CSF) in a grounded grid configuration. In this paper, the design of the new model as well as the prototype manufacturing schedule are presented in more detail.

  9. The energy spectrum of 0.16 to 2 MeV electrons during solar quiet times

    NASA Technical Reports Server (NTRS)

    Hurford, G. J.; Mewaldt, R. A.; Stone, E. C.; Vogt, R. E.

    1974-01-01

    New observations of the quiet-time energy spectrum of 0.16 to 2 MeV electrons were made with the Caltech Electron/Isotope Spectrometer which was launched on IMP-7 in September 1972. Earlier measurements of quiet-time electrons in this energy range by other groups have resulted in spectra differing by more than an order of magnitude in intensity. A minimum quiet-time flux somewhat lower than the lowest previously reported spectra and consistent with an extrapolation of the spectrum measured at higher energies was found. A galactic secondary source of knock-on electrons is consistent with the results and with independent studies of the interstellar spectra of cosmic ray nuclei provided that solar modulation does not suppress the 0.162 MeV electron flux by more than a factor of approximately 3. Although not required, other recently suggested sources may also contribute to the observed fluxes.

  10. M-shell electron capture and direct ionization of gold by 25-MeV carbon and 32-MeV oxygen ions

    NASA Astrophysics Data System (ADS)

    Andrews, M. C.; McDaniel, F. D.; Duggan, J. L.; Miller, P. D.; Pepmiller, P. L.; Krause, H. F.; Rosseel, T. M.; Rayburn, L. A.; Mehta, R.; Lapicki, G.

    1985-05-01

    M-shell X-ray production cross sections have been measured for thin solid targets of Au for 25 MeV 126C q+ ( q = 4, 5, 6) and for 32 MeV 168O q+ ( q = 5, 7, 8). The microscopic cross sections were determined from measurements made with targets ranging in thickness from 0.5 to 100 μg/cm 2. For projectiles with one or two K-shell vacancies, the target M-shell X-ray production cross sections are found to be enhanced over those by projectiles without a K-shell vacancy. The sum of direct ionization to the continuum (DI) and electron capture (EC) to the L, M, N.. shells and EC to the K-shell of the projectile have been extracted from the data. The results are compared with the predictions of first Born theories, i.e. PWBA for DI and OBK of Nikolaev for EC and the ECPSSR approach that accounts for energy loss. Coulomb deflection and relativistic effects in the perturbed stationary state theory.

  11. A comparison of radiation damage in transistors from cobalt-60 gamma rays and 2.2 MeV electrons

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Price, W. E.; Gauthier, M. K.

    1982-01-01

    The total ionizing dose response of ten bipolar transistor types has been measured using Co-60 gamma rays and 2.2 MeV electrons from exposure levels of 750, 1500, and 3000 Gy(Si). Gain measurements were made for a range of collector-emitter voltages and collector currents.

  12. Experimental Characterization of the Transverse Phase Space of a 60-MeV Electron Beam Through a Compressor Chicane

    SciTech Connect

    Zhou, F.; Kabel, A.; Rosenzweig, J.; Agustsson, R.; Andonian, G.; Cline, D.; Murokh, A.; Yakimenko, V.; /UCLA /SLAC /Brookhaven

    2007-02-12

    Space charge and coherent synchrotron radiation may deteriorate electron beam quality when the beam passes through a magnetic bunch compressor. This paper presents the transverse phase-space tomographic measurements for a compressed beam at 60 MeV, around which energy the first stage of magnetic bunch compression takes place in most advanced linacs. Transverse phase-space bifurcation of a compressed beam is observed at that energy, but the degree of the space charge-induced bifurcation is appreciably lower than the one observed at 12 MeV.

  13. Interpretation of recent positron-electron measurements between 20 and 800 MeV. [interplanetary cosmic ray solar modulation

    NASA Technical Reports Server (NTRS)

    Pellerin, C. J.; Hartman, R. C.

    1975-01-01

    Recently measured positron and negatron spectra are discussed with regard to the problem of solar modulation. At energies above 180 MeV, the spherically symmetric Fokker-Planck equation with a diffusion coefficient proportional to particle rigidity provides reasonable fits to both the positron and total electron data. At energies below 180 MeV, the data are consistent with a continuation of the same diffusion coefficient and a local source of negatrons or with a change in the diffusion coefficient to a constant value.

  14. Electric-field-induced electron detachment of 800-MeV H{sup {minus}} ions

    SciTech Connect

    Keating, P.B.; Gulley, M.S.; Bryant, H.C.; MacKerrow, E.P.; Miller, W.A.; Rislove, D.C.; Cohen, S.; Donahue, J.B.; Fitzgerald, D.H.; Funk, D.J.; Frankle, S.C.; Hutson, R.L.; Macek, R.J.; Plum, M.A.; Stanciu, N.G.; van Dyck, O.B.; Wilkinson, C.A.

    1995-12-01

    The lifetime of 800-MeV H{sup {minus}} ions against electron detachment in a static electric field was measured over a range of eight orders of magnitude in experiments at the High Resolution Atomic Beam Facility of the Los Alamos Meson Physics Facility. The ions traversed a linear gradient magnetic field of 1.3-T peak strength resulting in a 6-MV/cm peak rest-frame electric field capable of stripping a large fraction of H{sup {minus}} ions. The unstripped H{sup {minus}} ions, neutral H{sup 0} atoms, and protons were detected 5.5 m from the magnet. This spectrum was analyzed to determine the lifetime of the H{sup {minus}} ion versus electric-field strength and the results were compared with previous studies. Three parametrizations of the lifetime formula based on an existing theory were used to calculate the stripping probability. The data were fit to the lifetime formula and good agreement with theoretical predictions was found. Finally, a possible experiment for observing excited states of H{sup {minus}} is briefly discussed.

  15. Preliminary Safety Analysis Report (PSAR), The NSLS 200 MeV Linear Electron Accelerator

    SciTech Connect

    Blumberg, L.N.; Ackerman, A.I.; Dickinson, T.; Heese, R.N.; Larson, R.A.; Neuls, C.W.; Pjerov, S.; Sheehan, J.F.

    1993-06-15

    The radiological, fire and electrical hazards posed by a 200 MeV electron Linear Accelerator, which the NSLS Department will install and commission within a newly assembled structure, are addressed in this Preliminary Safety Analysis Report. Although it is clear that this accelerator is intended to be the injector for a future experimental facility, we address only the Linac in the present PSAR since neither the final design nor the operating characteristics of the experimental facility are known at the present time. The fire detection and control system to be installed in the building is judged to be completely adequate in terms of the marginal hazard presented - no combustible materials other than the usual cabling associated with such a facility have been identified. Likewise, electrical hazards associated with power supplies for the beam transport magnets and accelerator components such as the accelerator klystrons and electron gun are classified as marginal in terms of potential personnel injury, cost of equipment lost, program downtime and public impact perceptions as defined in the BNL Environmental Safety and Health Manual and the probability of occurrence is deemed to be remote. No unusual features have been identified for the power supplies or electrical distribution system, and normal and customary electrical safety standards as practiced throughout the NSLS complex and the Laboratory are specified in this report. The radiation safety hazards are similarly judged to be marginal in terms of probability of occurrence and potential injury consequences since, for the low intensity operation proposed - a factor of 25 less than the maximum Linac capability specified by the vendor - the average beam power is only 0.4 watts. The shielding specifications given in this report will give adequate protection to both the general public and nonradiation workers in areas adjacent to the building as well as radiation workers within the controlled access building.

  16. Laser Wakefield Acceleration of High-Quality Electron Beams to 300 MeV and Efficient Initiation of Photonuclear Reactions

    SciTech Connect

    Reed, S. A.; Naumova, N.; Vane, C Randy; Beene, James R; Bulanov, S. S.; Chvykov, V.; Hou, B.; Kalintchenko, G.; Matsuoka, T.; Rousseau, P.; Schultz, David Robert; Stracener, Daniel W; Yanovsky, V.; Maksimchuk, A.

    2006-11-01

    By focusing 40-TW, 30-fs laser pulses to the intensity of 1019 W/cm2 onto a supersonic He gas jet, we generated quasi-monoenergetic electron beams for plasma density in the narrow range of 1.5<= ne <=3 1019 cm3. We show that the energy, charge, divergence and pointing stability of the beam vary sensitively with ne within this range. The observed variations can be explained physically by the interplay among pump depletion and dephasing between accelerated electrons and plasma wave. An optimized quasi-monoenergetic beam of over 300 MeV and 10 mrad angular divergence is demonstrated at a plasma density of ne~1.5 1019 cm3. The quasi-monoenergeic electron beams with energy of 100-150 MeV and charge of 0.5 nC have been used to perform gamma-nuclear photofission of natural uranium targets. Through bremsstrahlung emission, such electron beams are well suited for the efficient generation of high energy (tens of MeV) gamma-rays necessary to induce photofission reactions. Quantitative gamma-ray spectroscopy of the irradiated U sample shows that more than ~105 photonuclear reactions have been produced per Joule of laser energy, which is 10 to 50 times higher than in a previously reported experiments

  17. Laser Wakefield Acceleration of High-Quality Electron Beams to 300 MeV and Efficient Initiation of Photonuclear Reactions

    SciTech Connect

    Reed, S. A.; Naumova, N.; Bulanov, S. S.; Chvykov, V.; Hou, B.; Kalintchenko, G.; Matsuoka, T.; Rousseau, P.; Yanovsky, V.; Maksimchuk, A.; Vane, C. R.; Beene, J. R.; Schultz, D. R.; Stracener, D. W.

    2006-11-27

    By focusing 40-TW, 30-fs laser pulses to the intensity of 1019 W/cm2 onto a supersonic He gas jet, we generated quasi-monoenergetic electron beams for plasma density in the narrow range of 1.5{<=} ne {<=}3x1019 cm3. We show that the energy, charge, divergence and pointing stability of the beam vary sensitively with ne within this range. The observed variations can be explained physically by the interplay among pump depletion and dephasing between accelerated electrons and plasma wave. An optimized quasi-monoenergetic beam of over 300 MeV and 10 mrad angular divergence is demonstrated at a plasma density of ne{approx}1.5x1019 cm3. The quasi-monoenergeic electron beams with energy of 100-150 MeV and charge of 0.5 nC have been used to perform {gamma}-nuclear photofission of natural uranium targets. Through bremsstrahlung emission, such electron beams are well suited for the efficient generation of high energy (tens of MeV) {gamma}-rays necessary to induce photofission reactions. Quantitative {gamma}-ray spectroscopy of the irradiated U sample shows that more than {approx}105 photonuclear reactions have been produced per Joule of laser energy, which is 10 to 50 times higher than in a previously reported experiments.

  18. Convoy electrons emitted by 2-MeV He + ions at grazing incidence on KCl(0 0 1)

    NASA Astrophysics Data System (ADS)

    Nakajima, K.; Nakamoto, A.; Suzuki, M.; Kimura, K.

    2006-07-01

    Convoy electrons produced during grazing angle scattering of 2-MeV He + ions at a clean (0 0 1) surface of KCl are measured to see the effect of the surface track potential. The measurement is performed at 230 °C with a beam current far below 1 pA to avoid macroscopic charging. The observed convoy electron energy coincides with the energy of the electron isotachic to the incident ion. This suggests that the effect of the surface track potential is accidentally cancelled out by the surface wake potential.

  19. Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

    SciTech Connect

    Bhat, Sathyanarayana Rao, Asha; Krishnan, Sheeja; Sanjeev, Ganesh; Suresh, E. P.

    2014-04-24

    The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.

  20. Low energy spread 100 MeV-1 GeV electron bunches from laserwakefiel d acceleration at LOASIS

    SciTech Connect

    Geddes, C.G.R.; Esarey, E.; Michel, P.; Nagler, B.; Nakamura, K.; Plateau, G.R.; Schroeder, C.B.; Shadwick, B.A.; Toth, Cs.; Van Tilborg,J.; Leemans, W.P.; Hooker, S.M.; Gonsalves, A.J.; Michel, E.; Cary, J.R.; and Bruhwiler, D.

    2006-08-01

    Experiments at the LOASIS laboratory of LBNL recentlydemonstrated production of 100 MeV electron beams with low energy spreadand low divergence from laser wakefield acceleration. The radiationpressure of a 10 TW laser pulse guided over 10 diffraction ranges by aplasma density channel was used to drive an intense plasma wave(wakefield), producing acceleration gradients on the order of 100 GV/m ina mm-scale channel. Beam energy has now been increased from 100 to 1000MeV by using a cm-scale guiding channel at lower density, driven by a 40TW laser, demonstrating the anticipated scaling to higher beam energies.Particle simulations indicate that the low energy spread beams wereproduced from self trapped electrons through the interplay of trapping,loading, and dephasing. Other experiments and simulations are alsounderway to control injection of particles into the wake, and henceimprove beam quality and stability further.

  1. The energy spectrum of 20 keV-20 MeV electrons accelerated in large solar flares

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Mewaldt, R. A.; Van Hollebeke, M. A. I.

    1982-01-01

    IMP 6, 7, and 8 measurements of the energy spectrum of 20 keV to 20 MeV electrons observed from large solar flares are presented. To minimize propagation effects, only events from flares at W30 deg to W90 deg solar longitude are considered. The energy spectra are constructed using the maximum flux observed at each energy. It is shown that these spectra are representative of the spectra of the electrons escaping from the sun over this range of energies. It is found that every event shows the same spectral shape: a double power law with a smooth transition around 100-200 keV and power law exponents of 0.6-2.0 below and 2.4-4.3 above. The more intense the event, the harder the observed spectrum; in certain cases, the spectra are observed to steepen above 3 MeV.

  2. Backward-going MeV electrons and gamma rays from 1018 W/cm2 laser interactions with water

    NASA Astrophysics Data System (ADS)

    Feister, Scott; Morrison, John T.; Frische, Kyle D.; Orban, Chris; Ovchinnikov, Vladimir M.; Nees, John A.; Austin, Drake R.; Chowdhury, Enam A.; Freeman, Richard R.; Roquemore, W. Melvyn

    2015-05-01

    Gamma rays with ~1 MeV energy are measured following the relativistic interaction of a 3 mJ, 1018 W/cm2 short pulse laser with a 30 μm diameter flowing water column. Contrary to expectations, radiation emission is peaked in the direction opposite to the normally-incident laser propagation (specular direction). Experimental measurements and particle-in-cell (PIC) simulations of laser-plasma interaction show a pre-formed-plasma-dependent, backward-going, beam-like primary electron source. The MeV component of the electron and gamma ray spectrum, which is more than five times the ponderomotive energy scale of the laser, is highly sensitive to the presence of a nanosecond-timescale laser pre-pulse. This research was sponsored by the Quantum and Non-Equilibrium Processes Division of the Air Force Office of Scientific Research, under the management of Dr. Enrique Parra, Program Manager.

  3. A 50-MeV mm-wave electron linear accelerator system for production of tunable short wavelength synchrotron radiation

    SciTech Connect

    Nassiri, A.; Kustom, R.L.; Mills, F.E.; Kang, Y.W.; Matthews, P.J.; Grudzien, D.; Song, J.; Horan, D.; Feinerman, A.D.; Willke, T.L. |; Henke, H. |

    1993-12-31

    The Advanced Photon Source (APS) at Argonne in collaboration with the University of Illinois at Chicago and the University of Wisconsin at Madison is developing a new millimeter wavelength, 50-MeV electron linear accelerator system for production of coherent tunable wavelength synchrotron radiation. Modern micromachining techniques based on deep etch x-ray lithography, LIGA (Lithografie, Galvanoformung, Abformung), capable of producing high-aspect ratio structures are being considered for the fabrication of the accelerating components.

  4. Absolute Calibration of Image Plate for electrons at energy between 100 keV and 4 MeV

    SciTech Connect

    Chen, H; Back, N L; Eder, D C; Ping, Y; Song, P M; Throop, A

    2007-12-10

    The authors measured the absolute response of image plate (Fuji BAS SR2040) for electrons at energies between 100 keV to 4 MeV using an electron spectrometer. The electron source was produced from a short pulse laser irradiated on the solid density targets. This paper presents the calibration results of image plate Photon Stimulated Luminescence PSL per electrons at this energy range. The Monte Carlo radiation transport code MCNPX results are also presented for three representative incident angles onto the image plates and corresponding electron energies depositions at these angles. These provide a complete set of tools that allows extraction of the absolute calibration to other spectrometer setting at this electron energy range.

  5. Coherent bremsstrahlung and channeling radiation from electrons of one to three MeV in silicon and gold

    SciTech Connect

    Watson, James Edwin

    1981-01-01

    The observation of sharp peaks in the x-ray spectrum from 1 to 3 MeV electrons striking thin single crystals of silicon and gold is reported. These peaks were observed in the range 1 to 25 keV. The peaks are of two different origins, both direct results of the periodic nature of the target crystals. The first kind of radiation is caused by the interference of incoming and scattered electron wave functions. Because of the periodicity of the target material there is a coherence effect for certain bremsstrahlung wave vectors. This coherent bremsstrahlung, though well known at very high electron energies, has never been adequately studied at electron energies below several hundred MeV. Detailed agreement between theoretical prediction and observation in silicon is shown. The second kind of radiation is caused by electrons channeled along major crystal axes. The electrons enter certain quantized orbits as they channel and may emit photons as a consequence of transitions between the various orbits. Observations of channeling radiation for various crystal axes in silicon are presented. Both phenomena were observed in gold, the first such observation for any metallic target.

  6. 1 MeV electron irradiation of solid Xe nanoclusters in Al : an in-situ HRTEM study.

    SciTech Connect

    Donnelly, S. E.; Furuya, K.; Song, M.; Birtcher, R. C.; Allen, C. W.

    1997-12-05

    Thin film samples of a simple embedded nanocluster system consisting of solid Xe precipitates in Al have been subjected to 1 MeV electron irradiation in a high-voltage electron microscope. High-resolution images have been recorded on videotape in order to monitor the changes to the system resulting from the passage of electrons through the film. Inspection of the video recordings (in some cases frame-by-frame) reveals that complex, rapid processes occur under the electron beam. These include, movement of small clusters, coalescence of neighboring clusters, shape changes, the apparent melting and resolidification of the Xe, and the creation and annealing of extended defects within the Xe lattice. A tentative interpretation of some of the observations is presented in terms of the electron-induced displacement processes at the surface of the clusters.

  7. Induction and detection of radioactivity in foodstuffs irradiated with 10 MeV electrons and X-rays

    NASA Astrophysics Data System (ADS)

    Wakeford, C. A.; Blackburn, R.; Swallow, A. J.

    Induction of radioactivity by direct (γn) and indirect (nγ) means was measured in solutions and foods irradiated with 10 MeV electrons and X-rays, to a dose of 20 kGy. Both types of reaction occur to a very limited extent following electron irradiation and this is attributed to the low efficiency of bremsstrahlung production in the target. For X-rays below the 1981 JECFI recommended 5 MeV upper limit of energy, only four (γn) reactions are possible and all have stable products. However, the neutrons generated can undergo moderation and capture by a variety of nuclides. Of particular interest is the reaction 2H(γn) 1H since this has an abnormally low (γn) threshold of 2.2 MeV and deuterium occurs with a natural abundance of 0.015%; hence some neutron production in food is inevitable. A neutron flux of 1.79 × 10 5 [n cm -2 s -1] [μg(D) cm -3] -1[kGy s -1] -1 was estimated from the activity induced in a variety of neutron monitors, especially manganese-55, as measured by gamma spectrometry and Cerenkov techniques. Induced activities at the end of irradiation calculated for beef using this flux value total 90 Bq kg -1 which is of the same order as natural levels in food (approx. 100 Bq kg -1), and are in broad agreement with NRPB data.

  8. Magnetic drifts at Io - Depletion of 10-MeV electrons at Voyager 1 encounter due to a forbidden zone

    NASA Technical Reports Server (NTRS)

    Goldstein, B. E.; Ip, W.-H.

    1983-01-01

    A model for magnetic field lines is used to track the Voyager spacecraft trajectory past Io back to the equatorial plane in order to determine the cause of an observed depletion of 10 MeV electrons in Io's orbit. The field lines are in the vicinity of an Alfven wing, a noncompressive field perturbation. It is suggested that the Jovian magnetospheric drift features influence the behavior of particles around Io, which also has a zone of reduced convection velocity. An analytical model is developed that demonstrates that a forbidden zone may exist around Io due to the gradient drifts and reduced convection velocity, and projections of particles convecting to the Io surface agree well with the Voyager data for particle concentrations. Discrepancies in the measured 9 MeV fluxes with respect to Pioneer data indicate that a possible change in the Io conductance in the interval between the passages of the two spacecraft.

  9. Experimental and theoretical study of PXRC (Parametric X-Radiation at Channeling) from 255 MeV electrons in Si

    NASA Astrophysics Data System (ADS)

    Korotchenko, K. B.; Pivovarov, Yu. L.; Takabayashi, Y.

    2013-08-01

    The X-radiation from relativistic channeled electrons at the Bragg angles - Parametric X-Radiation at Channeling (PXRC) - is studied both experimentally and theoretically. The experiment was carried out using a 255 MeV electron beam from a Linac at newly constructed beam line for the study of interactions between a relativistic electron beam and crystals at the SAGA Light Source. The observed asymmetry of PXRC angular distribution at (2 2 0) planar channeling in a 20 μm Si is explained taking account of two quantum effects: initial populations and transverse form-factors of the quantum states of planar channeled electrons. Further perspectives for PXRC studies at SAGA-LS are analyzed.

  10. Study on geomagnetic storms driving motion of 0.1-2 MeV radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenxia; Li, Xinqiao

    2016-08-01

    Using more than five years' worth of data observed by the Instrument for the Detection of Particles (IDP) spectrometer onboard the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite, we studied the motion characteristics of energetic electrons in different regions, i.e., the inner radiation belt, the outer radiation belt, and the slot region in geomagnetic storms. We investigated the flux change of 0.1-2.4 MeV electrons and the energy change of 0.1-1.0 MeV electrons in these different regions. By cross correlation analysis, we came to the following conclusions. First, when Dst < -50, the correlation coefficient (c.c.) of the electron flux and Dst index ranges from -0.63 to -0.86, and the enhancement of the electron flux generally occurs during the storm's main and recovery phases. Second, the storms greatly influence the lower energy region of the electron energy spectrum in the inner radiation belt, while the enhancement in the higher energy region is more significant in the outer radiation belt and the slot region. Third, the effects of geomagnetic storms on electrons are not distinguished significantly between in the day and night, and independent of the timing of the events. For storms with -50 < Dst < -30, there is a negative correlation of -0.51 to -0.57 between the Dst index and the electron flux in the outer radiation belt. Our analysis suggests that strong storms cause energetic electron ejections across a wide range, and the ejection level is affected by the storm intensity. Furthermore, the electron energy region influenced by the strong geomagnetic storms is opposite in the inner and outer radiation belts. The proportion of electrons accelerated to relativistic energies is greater in the outer radiation and slot regions, while the ejection energetic electrons are more concentrated in the low energy region of the inner radiation belt. This phenomenon reflects the different electron injection mechanisms and

  11. The heliopause spectrum of galactic electrons below 4 MeV and implications for their re-acceleration.

    NASA Astrophysics Data System (ADS)

    Prinsloo, Phillip; Toit Strauss, Du; Potgieter, Marius

    2016-07-01

    With the availability of observations of electrons at energies exceeding roughly 4 MeV, from e.g. the Voyager and PAMELA missions, their intensity levels and energy distribution are relatively well-known at the heliopause, where input spectra are typically specified in cosmic-ray modulation models. Numerically solving a transport equation that accounts for the re-acceleration of galactic electrons, it becomes essential to specify the heliopause spectrum at very low energies, typically below 4 MeV, because the diffusive shock acceleration process of particles at any given energy is dependent on the spectral shape at lower energies. Informed by the results of both radio data surveys and galactic propagation modelling, a number of scenarios are considered for this very low-energy heliopause spectrum. Assuming rigidity-independent diffusion at the considered energies as an initial assumption, the contribution of re-accelerated electrons to intensity levels is probed for each of the aforementioned scenarios. The magnitudes of the resultant intensity increases are concluded to be highly dependent on the spectral shape specified for the heliopause at these low energies, with the softer distributions predictably yielding greater re-acceleration effects.

  12. MeV gamma-ray Compton camera using a gaseous electron tracker for background-suppressed observation

    NASA Astrophysics Data System (ADS)

    Takada, A.; Tanimori, T.; Kubo, H.; Parker, J. D.; Mizumoto, T.; Mizumura, Y.; Sawano, T.; Nakamura, K.; Matsuoka, Y.; Komura, S.; Nakamura, S.; Oda, M.; Miuchi, K.; Kurosawa, S.

    2014-07-01

    As a next generation MeV gamma-ray telescope, we develop an electron-tracking Compton camera (ETCC) that consists of a gaseous electron tracker surrounded by pixel scintillator arrays. The tracks of the Compton-recoil electron measured by the tracker restrict the incident gamma-ray direction to an arc region on the sky and reject background by using the energy loss rate dE/dx and a Compton-kinematics test. In 2013, we constructed, for a balloon experiment, a 30-cm-cubic ETCC with an effective area of ~1 cm2 for detecting sub-MeV gamma rays (5 σ detection of the Crab Nebula for 4 h). In future work, we will extend this ETCC to an effective area of ~10 cm2. In the present paper, we report the performance of the current ETCC.

  13. Higher-order corrections to electron-nucleus bremsstrahlung cross sections above a few MeV

    NASA Astrophysics Data System (ADS)

    Mangiarotti, A.; Martins, M. N.

    2016-08-01

    Despite the fact that the first calculations of nuclear bremsstrahlung cross sections were performed for relativistic electrons more than 80 years ago by Sauter, Bethe and Heitler, and Racah, a fully satisfactory solution to this problem is still missing up to the present day. Numerical approaches are impractical for electrons with energies above a few MeV because they require a prohibitively large number of partial waves. Analytic formulae need to describe simultaneously and accurately the interaction with the Coulomb field of the nucleus and the screening effect of the atomic electrons. In the present paper, a state-of-the-art analytic calculation will be discussed. In particular, higher-order corrections to the interaction with the Coulomb field of the nucleus, a subject seldom tackled in the past, are included and compared extensively with published data. The emerged difficulties will be highlighted, but unfortunately they can be overcome only with future large coordinated theoretical and experimental efforts.

  14. Thick target bremsstrahlung spectra for 1.00-, 1.25-, and 1.40-Mev electrons

    USGS Publications Warehouse

    Miller, W.; Motz, J.W.; Cialella, C.

    1954-01-01

    The spectrum of radiation produced by 1.0-, 1.25-, and 1.40-Mev electrons incident on a thick tungsten target was measured at 0A????and 90A????with the incident beam by a method involving the magnetic analysis of Compton electrons. The effects of electron scattering and energy loss in the target preclude any simple interpretation of this data to yield a differential bremsstrahlung cross section. However, an estimate of the spectra to be expected at 0A????and 90A????was obtained by combining the Sauter expression for the bremsstrahlung cross section with the available information on electron scatter and energy loss in the target and backscatter from the target. The reliability of the estimate is limited because the Sauter formula was calculated by using the Born approximation, the electron scattering calculations are applicable to an infinite medium only, and the backscatter was estimated empirically from Bothe's experimental data which were obtained with lower energy electrons (370 kev). Furthermore electron energy straggling was neglected. Nevertheless, the predicted spectral shapes at 0A????and 90A????and the relative intensities at these two angles are in qualitative agreement with the measured values. The absolute magnitudes of the measured intensities at both angles are about a factor of two greater than the predicted values. ?? 1954 The American Physical Society.

  15. Compton MeV Gamma-ray Source on Texas Petawatt Laser-Driven GeV Electron Accelerator

    NASA Astrophysics Data System (ADS)

    Shaw, Joseph M.; Tsai, Hai-En; Zgadzaj, Rafal; Wang, Xiaoming; Chang, Vincent; Fazel, Neil; Henderson, Watson; Downer, M. C.; Texas Petawatt Laser Team

    2015-11-01

    Compton Backscatter (CBS) from laser wakefield accelerated (LWFA) electron bunches is a promising compact, femtosecond (fs) source of tunable high-energy photons. CBS x-rays have been produced from LWFAs using two methods: (1) retro-reflection of the LWFA drive pulse via an in-line plasma mirror (PM); (2) scattering of a counter-propagating secondary pulse split from the drive pulse. Previously MeV photons were only demonstrated by the latter method, but the former method is self-aligning. Here, using the Texas Petawatt (TPW) laser and a self-aligned near-retro-reflecting PM, we generate bright CBS γ-rays with central energies higher than 10 MeV. The 100 μm focus of TPW delivers 100 J in 100 fs pulses, with intensity 6x1018 W/cm2 (a0 =1.5), to the entrance of a 6-cm long Helium gas cell. A thin, plastic PM immediately following the gas cell exit retro-reflects the LWFA driving pulse into the oncoming 0.5 - 2 GeV electron beam to produce a directional beam of γ-rays without significant bremsstrahlung background. A Pb-filter pack on a thick, pixelated, CsI(Tl) scintillator is used to estimate the spectrum via differential transmission and to observe the beam profile. Recorded beam profiles indicate a low divergence. Department of Physics, The University of Texas at Austin

  16. Calculation of Dose for Skyshine Radiation From a 45 MeV Electron LINAC

    NASA Astrophysics Data System (ADS)

    Hori, M.; Hikoji, M.; Takahashi, H.; Takahashi, K.; Kitaichi, M.; Sawamura, S.; Nojiri, I.

    1996-11-01

    Dose estimation for skyshine plays an important role in the evaluation of the environment around nuclear facilities. We performed calculations for the skyshine radiation from a Hokkaido University 45 MeV linear accelerator using a general purpose user's version of the EGS4 Monte Carlo Code. To verify accuracy of the code, the simulation results have been compared with our experimental results, in which a gated counting method was used to measure low-level pulsed leakage radiation. In experiment, measurements were carried out up to 600 m away from the LINAC. The simulation results are consistent with the experimental values at the distance between 100 and 400 m from the LINAC. However, agreements of both results up to 100 m from the LINAC are not as good because of the simplification of geometrical modeling in the simulation. It could be said that it is useful to apply this version to the calculation for skyshine.

  17. PALS and DSC measurements in 8 MeV electron irradiated natural rubber filled with different fillers

    NASA Astrophysics Data System (ADS)

    Mandal, Arunava; Pan, Sandip; Roychowdhury, Anirban; Sengupta, Asmita

    2015-10-01

    The effect of high energy electron irradiation on the microstructure and thermal properties of natural rubber (NR) filled with different fillers at different concentrations are studied. The samples are irradiated with 8 MeV electron beam to a total dose of 100 KGy. The change in free volume size and specific heat due to addition of fillers and irradiation are studied using positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC) respectively. The Positron lifetime spectra are de-convoluted into two components. The longer lived component (τo-Ps) signifies the pick-off annihilation of ortho-positronium (o-Ps) at free volume site which may be related to the radius of the free volume holes. It is observed that the specific heat (Cp) and free volume size are all affected by both irradiation and addition of fillers.

  18. Accuracy evaluation of a Compton X-ray spectrometer with bremsstrahlung X-rays generated by a 6 MeV electron bunch

    SciTech Connect

    Kojima, Sadaoki Arikawa, Yasunobu; Zhang, Zhe; Ikenouchi, Takahito; Morace, Alessio; Nagai, Takahiro; Abe, Yuki; Sakata, Shouhei; Inoue, Hiroaki; Utsugi, Masaru; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Fujioka, Shinsuke; Azechi, Hiroshi; Nishimura, Yasuhiko; Togawa, Hiromi; Ozaki, Tetsuo; Kato, Ryukou

    2014-11-15

    A Compton-scattering-based X-ray spectrometer is developed to obtain the energy distribution of fast electrons produced by intense laser and matter interactions. Bremsstrahlung X-rays generated by fast electrons in a material are used to measure fast electrons’ energy distribution in matter. In the Compton X-ray spectrometer, X-rays are converted into recoil electrons by Compton scattering in a converter made from fused silica glass, and a magnet-based electron energy analyzer is used to measure the energy distribution of the electrons that recoil in the direction of the incident X-rays. The spectrum of the incident X-rays is reconstructed from the energy distribution of the recoil electrons. The accuracy of this spectrometer is evaluated using a quasi-monoenergetic 6 MeV electron bunch that emanates from a linear accelerator. An electron bunch is injected into a 1.5 mm thick tungsten plate to produce bremsstrahlung X-rays. The spectrum of these bremsstrahlung X-rays is obtained in the range from 1 to 9 MeV. The energy of the electrons in the bunch is estimated using a Monte Carlo simulation of particle-matter interactions. The result shows that the spectrometer's energy accuracy is ±0.5 MeV for 6.0 MeV electrons.

  19. Reducing shield thickness and backscattered radiation using a multilayered shield for 6–10 MeV electron beams.

    PubMed

    Butson, Martin; Chen, Tom; Rattanavoang, Somkhit; Hellyer, James; Gray, Alison; Nelson, Vinod; Short, Richard; Rajapakse, Satya; Lee, James; Fogarty, Gerald; Izard, Michael; Hill, Robin

    2015-12-01

    Intraoral and external electron shields used in radiotherapy are designed to minimize radiation exposure to non-treatment tissue. Sites where shields are used include but are not limited to, the treatment of lips, cheeks and ears whilst shielding the underlying oral cavity, tongue, gingival or temporal region. A commonly known and published effect, concerns the enhancement in dose that can occur on the beam side on an electron shield caused by an increase in electron backscatter radiation. In this work a lead shield has been designed incorporating copper, aluminium and wax in a step down filter arrangement to minimise backscatter whilst minimizing overall shield thickness for better clinical setup and ease of use. For electron beams ranging from 6 to 10 MeV, a standard shield design of 4 mm lead, 0.6 mm copper, 1.0 mm aluminium and 1.5 mm wax (3.1 mm added filtration, 7.1 mm total thickness) provided adequate backscatter and transmission reduction to match a standard 4.5 mm lead and 10 mm wax (total thickness 14.5 mm) electron shield. Dose enhancement values of no more than 10 % were measured utilising this shield design with a 50 % reduction in shield thickness. The thinner shield will not only allow easier patient set up but should be tolerated better by patients when mucosal reactions occur as they place less physical pressure on these sites during treatment due to their smaller size. PMID:26482529

  20. Local electron spectrum above 100 MeV derived from gamma-ray emissivity spectra

    NASA Technical Reports Server (NTRS)

    Strong, A. W.

    1985-01-01

    Two new determinations of the local gamma-ray emmissivity spectrum are in good accord and were used to derive constraints on the local electron spectrum. The requirement for an electron intensity above 1 GeV larger than previously believed is confirmed and no low energy upturn is then needed.

  1. Optimization of a photoneutron source based on 10 MeV electron beam using Geant4 Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Askri, Boubaker

    2015-10-01

    Geant4 Monte Carlo code has been used to conceive and optimize a simple and compact neutron source based on a 10 MeV electron beam impinging on a tungsten target adjoined to a beryllium target. For this purpose, a precise photonuclear reaction cross-section model issued from the International Atomic Energy Agency (IAEA) database was linked to Geant4 to accurately simulate the interaction of low energy bremsstrahlung photons with beryllium material. A benchmark test showed that a good agreement was achieved when comparing the emitted neutron flux spectra predicted by Geant4 and Fluka codes for a beryllium cylinder bombarded with a 5 MeV photon beam. The source optimization was achieved through a two stage Monte Carlo simulation. In the first stage, the distributions of the seven phase space coordinates of the bremsstrahlung photons at the boundaries of the tungsten target were determined. In the second stage events corresponding to photons emitted according to these distributions were tracked. A neutron yield of 4.8 × 1010 neutrons/mA/s was obtained at 20 cm from the beryllium target. A thermal neutron yield of 1.5 × 109 neutrons/mA/s was obtained after introducing a spherical shell of polyethylene as a neutron moderator.

  2. Characterization of MeV Electron Generation using 527 nm Laser Pulses for Fast Ignition

    NASA Astrophysics Data System (ADS)

    Fedosejevs, Robert; Higginson, D. P.; Friesen, H.; Sorokovikova, A.; Jarrott, C. C.; Link, A.; Kemp, G. E.; Hey, D.; Ping, Y.; Bush, I.; Tiedje, H. F.; Mo, M. Z.; Tsui, Y. Y.; Westover, B.; Beg, F. N.; Akli, K. U.; Freeman, R. R.; van Woerkom, L. D.; Schumacher, D.; Chen, C.; McLean, H. S.; Patel, P.; Doeppner, T.; Stephens, R. B.; Pasley, J.

    2011-10-01

    J WESTWOOD, J TAIT, A BEAUDRY, S SINGH, U of Alberta, and MH Key, LLNL. We investigate electron generation at intensities of relevance to Fast Ignition using second harmonic laser pulses, motivated by the need to understand the wavelength scaling of the processes and also the ability to obtain clean, prepulse free, target interaction conditions. 700fs duration pulses with peak intensities up to 5 x 1019 W cm-2 were employed at the TITAN laser facility at LLNL. Both planar and cone target geometries were studied using copper k-alpha imaging of tracer layers, Bremsstrahlung x-ray emission measurements of conversion efficiency and beam divergence and magnetic spectrometer measurements of escaping electrons to characterize the electron generation and propagation. Results of electron temperature and angular divergence will be presented.

  3. Electron beam characteristics of the 50-MeV racetrack microtron.

    PubMed

    Karlsson, M; Nyström, H; Svensson, H

    1992-01-01

    Electron beams in the MM50 racetrack microtron are generated by computer controlled scanning of a well-focused electron pencil beam. The treatment head is optimized to give a minimum of scatter between the source position and the collimator plane by a general minimization of all scattering material in the beam and by replacement of the air in the treatment head by helium, which has a much lower linear scattering power than air. A double-focused multileaf collimator with a 31-cm collimator to patient distance is used both for electron and photon collimation. In general, no extra electron collimation is needed for the standard SSD of 100 cm. To make irregular field collimation at a distance this far from the patient possible, a number of requirements have to be fulfilled regarding the virtual source position and the spatial and angular distribution of the initial electron beam. The virtual source position has been found to be at a fixed position for different irradiation parameters. This is important for the use of the light field in electron beam treatment but also for achieving a high degree of accuracy in the dosimetry. Scatter from the multileaf collimator has not been found to give any significant contribution to the radiation field or to the monitor output factor of the MM50. Experimental dose distribution data on the MM50 have been compared to data both from other types of treatment units and to Monte Carlo simulations. PMID:1584123

  4. A ROLE OF MAGNETOSONIC PULSES ON VARIATIONS OF VOYAGER-1 MeV ELECTRON INTENSITY IN THE HELIOSHEATH

    SciTech Connect

    Washimi, H.; Zank, G. P.; Hu, Q.; Florinski, V.; Webber, W.; Adams, J.; Kubo, Y.

    2012-09-20

    Voyager 1 (V1) spacecraft observed electrons of 6-14 MeV in the heliosheath which showed several enhancements of significant flux variation. We compare these temporal electron flux variations, from the time when V1 crossed the termination shock (TS) up to mid-2008, with dynamical phenomena in the heliosheath that are obtained from our MHD simulations which are based on Voyager 2 (V2) observed solar-wind data. Our simulations indicate that all electron flux enhancements, except for one, correspond fairly well to the times when a magnetosonic (MS) pulse was driven downstream of the TS due to collision of interplanetary shock (IPS) or shock-driven MS pulse and its reflection in the heliosheath that either passed V1, or collided with the TS or with the plasma sheet near the heliopause (HP). This result suggests that these enhancements in the electron flux should correspond to either direct or indirect effects of MS pulses in the heliosheath driven by IPSs. The scale of the heliosphere is estimated by comparing V1-observed magnetic field intensity with the simulated intensity which suggests that V1 is possibly located near the HP within 4-8 AU at the present time.

  5. A Role of Magnetosonic Pulses on Variations of Voyager-1 MeV Electron Intensity in the Heliosheath

    NASA Astrophysics Data System (ADS)

    Washimi, H.; Webber, W.; Zank, G. P.; Hu, Q.; Florinski, V.; Adams, J.; Kubo, Y.

    2012-09-01

    Voyager 1 (V1) spacecraft observed electrons of 6-14 MeV in the heliosheath which showed several enhancements of significant flux variation. We compare these temporal electron flux variations, from the time when V1 crossed the termination shock (TS) up to mid-2008, with dynamical phenomena in the heliosheath that are obtained from our MHD simulations which are based on Voyager 2 (V2) observed solar-wind data. Our simulations indicate that all electron flux enhancements, except for one, correspond fairly well to the times when a magnetosonic (MS) pulse was driven downstream of the TS due to collision of interplanetary shock (IPS) or shock-driven MS pulse and its reflection in the heliosheath that either passed V1, or collided with the TS or with the plasma sheet near the heliopause (HP). This result suggests that these enhancements in the electron flux should correspond to either direct or indirect effects of MS pulses in the heliosheath driven by IPSs. The scale of the heliosphere is estimated by comparing V1-observed magnetic field intensity with the simulated intensity which suggests that V1 is possibly located near the HP within 4-8 AU at the present time.

  6. The radiation field measurement and analysis outside the shielding of A 10 MeV electron irradiation accelerator

    NASA Astrophysics Data System (ADS)

    Shang, Jing; Li, Juexin; Xu, Bing; Li, Yuxiong

    2011-10-01

    Electron accelerators are employed widely for diverse purposes in the irradiation-processing industry, from sterilizing medical products to treating gemstones. Because accelerators offer high efficiency, high power, and require little preventative maintenance, they are becoming more and more popular than using the 60Co isotope approach. However, the electron accelerator exposes potential radiation hazards. To protect workers and the public from exposure to radiation, the radiation field around the electronic accelerator must be assessed, especially that outside the shielding. Thus, we measured the radiation dose at different positions outside the shielding of a 10-MeV electron accelerator using a new data-acquisition unit named Mini-DDL (Mini-Digital Data Logging). The measurements accurately reflect the accelerator's radiation status. In this paper, we present our findings, results and compare them with our theoretical calculations. We conclude that the measurements taken outside the irradiation hall are consistent with the findings from our calculations, except in the maze outside the door of the accelerator room. We discuss the reason for this discrepancy.

  7. Backward-propagating MeV electrons from 1018 W/cm2 laser interactions with water

    NASA Astrophysics Data System (ADS)

    Morrison, J. T.; Chowdhury, E. A.; Frische, K. D.; Feister, S.; Ovchinnikov, V. M.; Nees, J. A.; Orban, C.; Freeman, R. R.; Roquemore, W. M.

    2015-04-01

    We present an experimental study of the generation of ˜MeV electrons opposite to the direction of laser propagation following the relativistic interaction at normal incidence of a ˜3 mJ, 1018 W/cm2 short pulse laser with a flowing 30 μm diameter water column target. Faraday cup measurements record hundreds of pC charge accelerated to energies exceeding 120 keV, and energy-resolved measurements of secondary x-ray emissions reveal an x-ray spectrum peaking above 800 keV, which is significantly higher energy than previous studies with similar experimental conditions and more than five times the ˜110 keV ponderomotive energy scale for the laser. We show that the energetic x-rays generated in the experiment result from backward-going, high-energy electrons interacting with the focusing optic, and vacuum chamber walls with only a small component of x-ray emission emerging from the target itself. We also demonstrate that the high energy radiation can be suppressed through the attenuation of the nanosecond-scale pre-pulse. These results are supported by 2D particle-in-cell simulations of the laser-plasma interaction, which exhibit beam-like backward-propagating MeV electrons.

  8. Neutron yield and induced radioactivity: a study of 235-MeV proton and 3-GeV electron accelerators.

    PubMed

    Hsu, Yung-Cheng; Lai, Bo-Lun; Sheu, Rong-Jiun

    2016-01-01

    This study evaluated the magnitude of potential neutron yield and induced radioactivity of two new accelerators in Taiwan: a 235-MeV proton cyclotron for radiation therapy and a 3-GeV electron synchrotron serving as the injector for the Taiwan Photon Source. From a nuclear interaction point of view, neutron production from targets bombarded with high-energy particles is intrinsically related to the resulting target activation. Two multi-particle interaction and transport codes, FLUKA and MCNPX, were used in this study. To ensure prediction quality, much effort was devoted to the associated benchmark calculations. Comparisons of the accelerators' results for three target materials (copper, stainless steel and tissue) are presented. Although the proton-induced neutron yields were higher than those induced by electrons, the maximal neutron production rates of both accelerators were comparable according to their respective beam outputs during typical operation. Activation products in the targets of the two accelerators were unexpectedly similar because the primary reaction channels for proton- and electron-induced activation are (p,pn) and (γ,n), respectively. The resulting residual activities and remnant dose rates as a function of time were examined and discussed. PMID:25628454

  9. MeV femtosecond electron pulses from direct-field acceleration in low density atomic gases

    NASA Astrophysics Data System (ADS)

    Varin, Charles; Marceau, Vincent; Hogan-Lamarre, Pascal; Fennel, Thomas; Piché, Michel; Brabec, Thomas

    2016-01-01

    Using three-dimensional particle-in-cell (3DPIC) simulations, we show that few-MeV electrons can be produced by tightly focusing few-cycle radially-polarized laser pulses in a low-density atomic gas. In particular, it is observed that for the few-TW laser power needed to reach relativistic electron energies, longitudinal attosecond microbunching occurs naturally, resulting in femtosecond structures with high-contrast attosecond density modulations. The 3DPIC simulations show that in the relativistic regime the leading pulse of these attosecond substructures survives to propagation over extended distances, suggesting that it could be delivered to a distant target, with the help of a properly designed transport beamline.

  10. High-resolution study of electron capture by 72- and 52-MeV 3He projectiles from targets of high atomic number

    NASA Astrophysics Data System (ADS)

    Katayama, I.; Ikegami, H.; Ogawa, H.; Haruyama, Y.; Tozaki, M.; Aoki, A.; Fukuzawa, F.; Yoshida, K.; Sugai, I.

    1996-01-01

    An electron capture at the cyclotron energy has been explored by using a high-resolution magnetic spectrograph. The K-shell electron capture from heavy elements (V, Cr, Cu, Ge, Nb, Ag, and Sn) by 3He2+ projectiles at 52 and 72 MeV was measured. The dependence of the cross sections on the atomic number of the target obtained at these two energies are compared with current electron-capture theories.

  11. Electron Impact Ionization: A New Parameterization for 100 eV to 1 MeV Electrons

    NASA Technical Reports Server (NTRS)

    Fang, Xiaohua; Randall, Cora E.; Lummerzheim, Dirk; Solomon, Stanley C.; Mills, Michael J.; Marsh, Daniel; Jackman, Charles H.; Wang, Wenbin; Lu, Gang

    2008-01-01

    Low, medium and high energy electrons can penetrate to the thermosphere (90-400 km; 55-240 miles) and mesosphere (50-90 km; 30-55 miles). These precipitating electrons ionize that region of the atmosphere, creating positively charged atoms and molecules and knocking off other negatively charged electrons. The precipitating electrons also create nitrogen-containing compounds along with other constituents. Since the electron precipitation amounts change within minutes, it is necessary to have a rapid method of computing the ionization and production of nitrogen-containing compounds for inclusion in computationally-demanding global models. A new methodology has been developed, which has parameterized a more detailed model computation of the ionizing impact of precipitating electrons over the very large range of 100 eV up to 1,000,000 eV. This new parameterization method is more accurate than a previous parameterization scheme, when compared with the more detailed model computation. Global models at the National Center for Atmospheric Research will use this new parameterization method in the near future.

  12. Optical absorption in fused silica at elevated temperatures during 1.5-MeV electron irradiation

    NASA Technical Reports Server (NTRS)

    Smith, A. B.

    1972-01-01

    An experimental determination of the optical transmission of Corning 7940 UV and Suprasil 1 and 2 fused silica has been made during 1.5-MeV electron bombardment. The fused silica reached temperatures ranging from 150 to 1000 C. The Lewis Research Center dynamitron provided electron current densities which corresponded to a dose rate of 2.6 to 20 Mrad/sec. The irradiation induced absorption was measured at 215.0, 270.0, and 450.0 nm (2150, 2700, 4500 A). The length of each irradiation was sufficient so that an equilibrium between radiation induced coloration and high temperature annealing was reached. The experimental results indicate a significant optical absorption, with values of the induced absorption coefficient at 215.0 nm (2150 A) of 14.5 to 2.2/cm, at 270.0 nm (2700 A) of 9.7 to 3.0/cm and at 450.0 nm (4500 A) of 3.7 to 0.5/cm. This would make the use of fused silica as the separating wall material in the nuclear light bulb propulsion concept questionable.

  13. Generation of 500 MeV-1 GeV energy electrons from laser wakefield acceleration via ionization induced injection using CO{sub 2} mixed in He

    SciTech Connect

    Mo, M. Z.; Ali, A.; Fedosejevs, R.; Fourmaux, S.; Lassonde, P.; Kieffer, J. C.

    2013-04-01

    Laser wakefield acceleration of 500 MeV to 1 GeV electron bunches has been demonstrated using ionization injection in mixtures of 4% to 10% of CO{sub 2} in He. 80 TW laser pulses were propagated through 5 mm gas jet targets at electron densities of 0.4-1.5 Multiplication-Sign 10{sup 19}cm{sup -3}. Ionization injection led to lower density thresholds, a higher total electron charge, and an increased probability of producing electrons above 500 MeV in energy compared to self-injection in He gas alone. Electrons with GeV energies were also observed on a few shots and indicative of an additional energy enhancement mechanism.

  14. The use of a diode matrix in commissioning activities for electron energies {>=}9 MeV: A feasibility study

    SciTech Connect

    Casanova Borca, Valeria; Pasquino, Massimo; Ozzello, Franca; Tofani, Santi

    2009-04-15

    The contribution of a commercially available diode matrix (MapCHECK trade mark sign , provided by Sun Nuclear, Melbourne, FL) for the commissioning procedures of the voxel based Monte Carlo (VMC++) algorithm for electron beams of MasterPlan treatment planning system was investigated. The attention is mainly focused on the calculation in homogeneous and heterogeneous phantoms. With this aim, following a data set similar to that proposed by Electron Collaborative Working Group (ECWG), the dose profiles and two-dimensional (2D) dose distributions measured by the diode matrix were compared with the calculated ones using the gamma analysis method with acceptance criteria for the dose difference and the distance to agreement equal to 4% and 4 mm, respectively. The average and standard deviation of the percentage of points satisfying the constraint {gamma}{<=}1 are 98.3{+-}4.1% and 99.3{+-}1.7% for the 9 and 12 MeV electron beam, respectively, showing that the accuracy of MasterPlan electron beam algorithm is good for simple two-dimensional geometries as well as for more complicated three-dimensional ones. The results are in agreement with those reported in literature by Cygler et al. [''Evaluation of the first commercial Monte Carlo dose calculation engine for electron beam treatment planning,'' Med. Phys. 31, 142-153 (2004)]. In addition, the authors have also analyzed the response of the 2D array in terms of dose profiles at different depths, comparing the results with those obtained in water phantom using an electron diode. The results show that in the low gradient regions there were no deviations larger than the criteria of acceptability set by Van Dyk et al. [''Commissioning and quality assurance of treatment planning computers,'' Int. J. Radiat. Oncol. Biol. Phys. 26, 261-273 (1993)]; in the high gradient region, the maximum deviations are less than 2 mm with most of the values less than 1 mm. The present article shows that MapCHECK trade mark sign can play a

  15. Determination of electron beam output factors for a 20-MeV linear accelerator.

    PubMed

    Mills, M D; Hogstrom, K R; Fields, R S

    1985-01-01

    The demands of a busy clinic require that basic machine calculations be performed as accurately, rapidly, and simply as possible. For the electron beam of the Therac 20 Saturne linear accelerator, a method suitable for a programmable calculator is described to predict the dose output from the measurement of selected fields. One-dimensional output factors were measured; these are defined as output factors of rectangular fields where one side is always equal to the side of the square reference field. The output of an arbitrary rectangular field X, Y is given by the product of the output factors OF(X,Y) = OF(X,10) X OF(10,Y), where 10 is the side of the square reference field. The measured data indicate that the output of very large rectangular and square fields is underestimated using this method for the lower energies. A correction factor of the form CF = C X [(X - 10)(Y - 10)/(X - 10)(Y - 10) 1/2] results in agreement with measured data to within 1.5% for all energies. PMID:3929052

  16. Radiation performance of GaAs concentrator cells for 0.4 to 12 MeV electrons and 0.1 to 37 MeV protons

    NASA Technical Reports Server (NTRS)

    Curtis, Henry B.; Anspaugh, Bruce

    1991-01-01

    Gallium arsenide concentrator cells have been irradiated with both electrons and protons with a wide variety of energies. The cells are made using OM-VPE growth process with a junction depth of a half micron. All data are taken with bare cells without coverglasses or shielding. Performance data are given at the designed concentration level of 100X AMO. Results are presented in a number of ways, including performance of electrical parameters (Pmax, Isc, and Voc) as a function of fluence for different electron and proton energies. Critical fluences (defined at a degradation of 25 percent in Pmax) are calculated for each energy level and presented for both electron and proton irradiations.

  17. Sudden Intensity Increases and Radial Gradient Changes of Cosmic Ray Mev Electrons and Protons Observed at Voyager 1 Beyond 111 AU in the Heliosheath

    NASA Technical Reports Server (NTRS)

    Webber, W. R.; Mcdonald, F. B.; Cummings, A. C.; Stone, E. C.; Heikkila, B.; Lal, N.

    2012-01-01

    Voyager 1 has entered regions of different propagation conditions for energetic cosmic rays in the outer heliosheathat a distance of about 111 AU from the Sun. The low energy 614 MeV galactic electron intensity increased by 20over a time period 10 days and the electron radial intensity gradient abruptly decreased from 19AU to 8AU at2009.7 at a radial distance of 111.2 AU. At about 2011.2 at a distance of 116.6 AU a second abrupt intensity increase of25 was observed for electrons. After the second sudden electron increase the radial intensity gradient increased to18AU. This large positive gradient and the 13 day periodic variations of 200 MeV particles observed near theend of 2011 indicate that V1 is still within the overall heliospheric modulating region. The implications of these resultsregarding the proximity of the heliopause are discussed.

  18. The thermoluminescence characteristics and the glow curves of Thulium doped silica fiber exposed to 10MV photon and 21MeV electron radiation.

    PubMed

    Alawiah, A; Alina, M S; Bauk, S; Abdul-Rashid, H A; Gieszczyk, W; Noramaliza, M N; Mahdiraji, G A; Tamchek, N; Zulkifli, M I; Bradley, D A; Marashdeh, M W

    2015-04-01

    The thermoluminescence (TL) glow curves and kinetics parameters of Thulium (Tm) doped silica cylindrical fibers (CF) are presented. A linear accelerator (LINAC) was used to deliver high-energy radiation of 21MeV electrons and 10MV photons. The CFs were irradiated in the dose range of 0.2-10Gy. The experimental glow curve data was reconstructed by using WinREMS. The WinGCF software was used for the kinetic parameters evaluation. The TL sensitivity of Tm-doped silica CF is about 2 times higher as compared to pure silica CF. Tm-doped silica CF seems to be more sensitive to 21MeV electrons than to 10MV photons. Surprisingly, no supralinearity was displayed and a sub-linear response of Tm-doped silica CF was observed within the analyzed dose range for both 21MeV electrons and 10MV photons. The Tm-doped silica CF glow curve consists of 5 individual glow peaks. The Ea of peak 4 and peak 5 was highly dependent on dose when irradiated with photons. We also noticed that the electron radiation (21MeV) caused a shift of glow peak by 7-13°C to the higher temperature region compared with photons radiation (10MV). Our Tm-doped fibers seem to give high TL response after 21MeV electrons, which gives around 2 times higher peak integral as compared with 10MV photon radiation. We concluded that peak 4 is the first-order kinetic peak and can be used as the main dosimetric peak of Tm-doped silica CF. PMID:25644081

  19. Statistical analysis of energetic electrons (3. 4-16 MeV) at geosynchronous altitude and their relationship to interplanetary parameters. Master's thesis

    SciTech Connect

    Smith, W.L.

    1983-12-01

    This analysis attempted to examine the relationship between energetic electrons in the magnetosphere between the energy levels of 3.4-16 MeV, solar wind speed, and the Bz component of the Interplanetary Magnetic Field (IMF). The statistical analysis was accomplished using the SPSS computerized package and data from DOD spacecraft 1979-053 at geosynchronous altitude. The electron flux data from this satellite was compared statistically with IMF and solar sind plasma data measured by other spacecraft located in the solar wind stream. Analytic techniques used included graphical plotting, descriptive statistics, scatter plots, correlation analysis, and analysis of variance (ANOVA) tests. This statistical analysis of energetic electrons at geosynchronous altitude and their relationship to solar wind speed and the IMF Bz component resulted in different findings for electron flux above and below approximately 6.6 MeV energy level. There was a weak, positive correlation between electron flux in the energy ranges 3.4 - 4.9 and 4.9 - 6.6 MeV and values of solar wind speed, after two days passage.

  20. Comparison of GATE/GEANT4 with EGSnrc and MCNP for electron dose calculations at energies between 15 keV and 20 MeV

    NASA Astrophysics Data System (ADS)

    Maigne, L.; Perrot, Y.; Schaart, D. R.; Donnarieix, D.; Breton, V.

    2011-02-01

    The GATE Monte Carlo simulation platform based on the GEANT4 toolkit has come into widespread use for simulating positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging devices. Here, we explore its use for calculating electron dose distributions in water. Mono-energetic electron dose point kernels and pencil beam kernels in water are calculated for different energies between 15 keV and 20 MeV by means of GATE 6.0, which makes use of the GEANT4 version 9.2 Standard Electromagnetic Physics Package. The results are compared to the well-validated codes EGSnrc and MCNP4C. It is shown that recent improvements made to the GEANT4/GATE software result in significantly better agreement with the other codes. We furthermore illustrate several issues of general interest to GATE and GEANT4 users who wish to perform accurate simulations involving electrons. Provided that the electron step size is sufficiently restricted, GATE 6.0 and EGSnrc dose point kernels are shown to agree to within less than 3% of the maximum dose between 50 keV and 4 MeV, while pencil beam kernels are found to agree to within less than 4% of the maximum dose between 15 keV and 20 MeV.

  1. Comparison of GATE/GEANT4 with EGSnrc and MCNP for electron dose calculations at energies between 15 keV and 20 MeV.

    PubMed

    Maigne, L; Perrot, Y; Schaart, D R; Donnarieix, D; Breton, V

    2011-02-01

    The GATE Monte Carlo simulation platform based on the GEANT4 toolkit has come into widespread use for simulating positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging devices. Here, we explore its use for calculating electron dose distributions in water. Mono-energetic electron dose point kernels and pencil beam kernels in water are calculated for different energies between 15 keV and 20 MeV by means of GATE 6.0, which makes use of the GEANT4 version 9.2 Standard Electromagnetic Physics Package. The results are compared to the well-validated codes EGSnrc and MCNP4C. It is shown that recent improvements made to the GEANT4/GATE software result in significantly better agreement with the other codes. We furthermore illustrate several issues of general interest to GATE and GEANT4 users who wish to perform accurate simulations involving electrons. Provided that the electron step size is sufficiently restricted, GATE 6.0 and EGSnrc dose point kernels are shown to agree to within less than 3% of the maximum dose between 50 keV and 4 MeV, while pencil beam kernels are found to agree to within less than 4% of the maximum dose between 15 keV and 20 MeV. PMID:21239846

  2. Experimental SF6/-//SF6 and Cl/-//CFC13 electron-attachment cross sections in the energy range 0-200 meV

    NASA Technical Reports Server (NTRS)

    Chutjian, A.

    1981-01-01

    Experimental cross sections for the electron-attachment processes for SF6(-)/SF6 and Cl(-)/CFl3 are reported in the energy range 0-200 meV by normalizing each attachment line shape to measurement of a thermal rate coefficient. When the same ion states are detected, good agreement is found between present values, for which a monoenergetic electron source is used, and swarm-unfolded results. The present data constitute a new limit for cross sections reported at high resolution at the lowest electron energy.

  3. Observation of Electron Cloud Stabilized 1 MeV Beam-Beam d+d Reactons in Self-Colliding Orbits and Feasibility of Electric Isotope Breeder

    NASA Astrophysics Data System (ADS)

    Maglich, Bogdan; Druey, Christian; Iyengar, P. K.; Srinivasan, Mahadeva

    2012-03-01

    D-D Self-Collider ^1,2 is only system in which beam-beam nuclear reactions demonstrated MeV energies. 1.45 MeV DC beam of D2^+ was injected into center of a weak-focusing magnetic field (Ni Ti) B=3.12 Tesla, and dissociated into 2 d^+ stored in Self-Colliding Orbits^3. Energy confinement time T = 23 s (vacuum limited p=10-9 torr), stabilized by driven electron oscillations^4. A simulation^5 shows that 1 DD neutron is produced at an energy cost of 5.36 MeV/n i.e. 140 MWh/g= 8,360/g vs. 160,000/g from beam - target. Simultaneously produced He^3 and T are not only free, but bring 45 fold gain. 5 d's of 0.75 MeV generate 1He^3 +1T +1p+ 1n at cost 5.36 MeV. Hence, it will produce 2 He^3 nuclei (1 He-3, 1 T) plus energy gain of 161 MeV. This will be reduced by the energy gain thus reducing cost to 4.5 from 5.6 MeV. Assumed ion density 5x10 ^14 was achieved in plasmas. Beam injection 100 mA. 1. PRL 54, 796 (1985) NIM A 271 p,.1-167; 2. AIP CP 311, 292 (93); 3. PRL 70, 1818 (93); 4.Part. Acc.1, (70); 5. ``50 Years with Fission'' Symp.Nat. Ac Sci., p. 761 (89)

  4. 47 CFR 3.20 - Application form.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... AUTHORITIES IN MARITIME AND MARITIME MOBILE-SATELLITE RADIO SERVICES Application Procedures § 3.20 Application form. Written application must be made to the Federal Communications Commission on FCC Form 44... 47 Telecommunication 1 2012-10-01 2012-10-01 false Application form. 3.20 Section...

  5. 47 CFR 3.20 - Application form.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... AUTHORITIES IN MARITIME AND MARITIME MOBILE-SATELLITE RADIO SERVICES Application Procedures § 3.20 Application form. Written application must be made to the Federal Communications Commission on FCC Form 44... 47 Telecommunication 1 2010-10-01 2010-10-01 false Application form. 3.20 Section...

  6. 47 CFR 3.20 - Application form.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... AUTHORITIES IN MARITIME AND MARITIME MOBILE-SATELLITE RADIO SERVICES Application Procedures § 3.20 Application form. Written application must be made to the Federal Communications Commission on FCC Form 44... 47 Telecommunication 1 2014-10-01 2014-10-01 false Application form. 3.20 Section...

  7. 47 CFR 3.20 - Application form.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... AUTHORITIES IN MARITIME AND MARITIME MOBILE-SATELLITE RADIO SERVICES Application Procedures § 3.20 Application form. Written application must be made to the Federal Communications Commission on FCC Form 44... 47 Telecommunication 1 2011-10-01 2011-10-01 false Application form. 3.20 Section...

  8. 47 CFR 3.20 - Application form.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... AUTHORITIES IN MARITIME AND MARITIME MOBILE-SATELLITE RADIO SERVICES Application Procedures § 3.20 Application form. Written application must be made to the Federal Communications Commission on FCC Form 44... 47 Telecommunication 1 2013-10-01 2013-10-01 false Application form. 3.20 Section...

  9. 42 CFR 3.20 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... individually identifiable health information as that term is defined in the HIPAA Privacy Rule at 45 CFR 160... otherwise authorized under State law to provide health care services, including— (i) A hospital, nursing... 42 Public Health 1 2010-10-01 2010-10-01 false Definitions. 3.20 Section 3.20 Public Health...

  10. Calculation of SF6-/SF6 and Cl-/CFCl3 electron attachment cross sections in the energy range 0-100 meV

    NASA Technical Reports Server (NTRS)

    Chutjian, A.

    1982-01-01

    Electron attachment cross sections for the processes SF6-/SF6 and Cl-/CFCl3 are calculated in a local theory using a model in which diatomic-like potential energy curves for the normal modes are constructed from available spectroscopic data. Thermally populated vibrational and rotational levels are included. Good agreement is found with experimental cross sections in the energy range 5-100 meV for a particular choice of potential energy curve parameters.

  11. Detection of interplanetary electrons from 18 keV to 1.8 MeV during solar quiet times, 1. On the origin of 200 KeV interplanetary electrons, 2.

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Anderson, K. A.; Cline, T. L.; Ramaty, R.; Fisk, L. A.

    1972-01-01

    A quiet time component of interplanetary electrons having energies above solar wind energies and below those characterized as cosmic radiation was observed. Its energy spectrum falls with energy from 18 keV to 1.8 MeV, but it shows a feature in the 100 to 300 keV range. The observed temporal variations of the intensity suggest that the 18 to 100 keV portion is solar and the 0.3 to 1.8 MeV portion is galactic in origin. Solar and terrestrial neutron decay electrons appear inadequate to explain the 100 to 300 keV feature.

  12. A comparison of radiation damage in liner ICs from cobalt-60 gamma rays and 2.2-MeV electrons

    NASA Technical Reports Server (NTRS)

    Gauthier, M. K.; Nichols, D. K.

    1983-01-01

    The total ionizing dose response of fourteen IC types from eight manufacturers was measured using Co-60 gamma rays and 2.2-MeV electrons for exposure levels of 100 to 20,000 Gy(Si). Key parameter measurements were made and compared for each device type. The data show that a Co-60 source is not a suitable simulation source for some systems because of the generally more damaging nature of electrons as well as the unpredictable nature of the individual device response to the two types of radiations used here.

  13. A comparison of radiation damage in linear ICs from Cobalt-60 gamma rays and 2.2 MeV electrons

    NASA Technical Reports Server (NTRS)

    Gauthier, M. K.; Nichols, D. K.

    1983-01-01

    The total ionizing dose response of fourteen IC types from eight manufacturers have been measured using Co-60 gamma rays and 2.2 MeV electrons for exposure levels of 100 to 20,000 Gy(Si). Key parameter measurements were made and compared for each device type. The data show that a Co-60 source may not be a suitable simulation source for some systems, because of the generally more damaging nature of electrons as well as the unpredictable nature of the individual device response to the two types of radiations used here.

  14. Recent results on fast intermediate velocity electron production induced by 19 + 45 A MeV 58Ni highly charged ions on thin solid targets

    NASA Astrophysics Data System (ADS)

    Lanzanò, G.; De Filippo, E.; Anzalone, A.; Arena, N.; Geraci, M.; Giustolisi, F.; Pagano, A.; Rothard, H.; Volant, C.

    2003-05-01

    In order to study the emission of energetic electrons induced by the impact of swift heavy ions on thin solid targets, we carried out a series of experiments at the superconducting cyclotron of the Catania Laboratori Nazionali del Sud. We report results on a recent experiment where electron-electron coincidences were measured in a forward ring by bombarding a thin carbon target of 7.4 μg/cm 2 with 19 + 45 A MeV 58Ni beam. The velocity1-velocity2 bidimensional plot is dominated by events in which the two detected electrons have a velocity close to the beam velocity 9.03 cm/ns (convoy electrons). The remaining small fraction of coincidences has still a convoy electron and a second electron having either a velocity almost twice the beam velocity 16.5 cm/ns (binary encounter, BE electrons) or a velocity of about 12.7 cm/ns intermediate between BE and convoy velocities (IV electrons). We interprete this last intermediate component as due to in-flight de-excitation of highly excited n +58Ni ions by Auger electrons. Although less distinct, we observe also an intense peak close to the convoy velocity peak, centered at ≈9.7 cm/ns, corresponding to electrons emitted with an energy of only about ≈170 eV in the projectile rest frame of reference.

  15. State-selective differential cross sections for double-electron capture in 0.25{endash}0.75-MeV He{sup 2+}-He collisions

    SciTech Connect

    Doerner, R.; Mergel, V.; Spielberger, L.; Jagutzki, O.; Schmidt-Boecking, H.; Ullrich, J.

    1998-01-01

    For 0.25{endash}0.75-MeV He{sup 2+} on He collisions we have measured total state selective double capture cross sections and cross sections differential in projectile scattering angle. For 0.25 MeV we present also state-selective scattering-angle-dependent double-capture cross sections. The projectile energy loss (the final electronic state) as well as the transverse momentum transfer (i.e., the projectile scattering angle) have been obtained by measuring the momentum vector of the recoil ion using cold target recoil ion momenum spectroscopy. The resonant transfer to the ground state is found to be by far the dominant double-capture channel. Capture to nonautoionizing excited states is smaller by about a factor of 7, and results in larger scattering angles than the ground-state double capture. {copyright} {ital 1998} {ital The American Physical Society}

  16. Demonstration of Single-Shot Picosecond Time-Resolved MeV Electron Imaging Using a Compact Permanent Magnet Quadrupole Based Lens

    NASA Astrophysics Data System (ADS)

    Cesar, D.; Maxson, J.; Musumeci, P.; Sun, Y.; Harrison, J.; Frigola, P.; O'Shea, F. H.; To, H.; Alesini, D.; Li, R. K.

    2016-07-01

    We present the results of an experiment where a short focal length (˜1.3 cm ), permanent magnet electron lens is used to image micron-size features (of a metal sample) with a single shot from an ultrahigh brightness picosecond-long 4 MeV electron beam emitted by a radio-frequency photoinjector. Magnification ratios in excess of 30 × were obtained using a triplet of compact, small gap (3.5 mm), Halbach-style permanent magnet quadrupoles with nearly 600 T /m field gradients. These results pave the way towards single-shot time-resolved electron microscopy and open new opportunities in the applications of high brightness electron beams.

  17. Generation of tunable, 100-800 MeV quasi-monoenergetic electron beams from a laser-wakefield accelerator in the blowout regime

    SciTech Connect

    Banerjee, S.; Powers, N. D.; Ramanathan, V.; Ghebregziabher, I.; Brown, K. J.; Maharjan, C. M.; Chen, S.; Umstadter, D. P.; Beck, A.; Lefebvre, E.; Kalmykov, S. Y.; Shadwick, B. A.

    2012-05-15

    In this paper, we present results on a scalable high-energy electron source based on laser wakefield acceleration. The electron accelerator using 30-80 TW, 30 fs laser pulses, operates in the blowout regime, and produces high-quality, quasi-monoenergetic electron beams in the range 100-800 MeV. These beams have angular divergence of 1-4 mrad, and 5%-25% energy spread, with a resulting brightness 10{sup 11} electrons mm{sup -2} MeV{sup -1} mrad{sup -2}. The beam parameters can be tuned by varying the laser and plasma conditions. The use of a high-quality laser pulse and appropriate target conditions enables optimization of beam quality, concentrating a significant fraction of the accelerated charge into the quasi-monoenergetic component.

  18. Design and Construction of a Faraday Cup for Electron Fluence Measurements in the Energy Range from 1 to 5 MeV

    NASA Astrophysics Data System (ADS)

    Korwin, D. M.; Vargas-Aburto, C.; Uribe, R. M.; Hudson, K. J.

    2003-03-01

    Electron beams are used in research and industry in order to develop new materials or change the physical properties of materials of technological interest (e.g. polymeric materials or semiconductors). Usually the physical or chemical effect produced by the electron beam is a function of the dose absorbed by the material and ultimately of the fluence of the incoming radiation. In many of these applications, such as the study of radiation damage in solar cells, the electron fluence is one of the parameters used to characterize the effect of the radiation on the semiconductor material. In this paper a description is presented of the design and construction of a Faraday Cup to measure electron beam fluence values in a 1 to 5 MeV, 150 kW electron accelerator used for radiation processing. At such high powers, the electron beam is continuously scanned back and forth in one direction in order to prevent the burning of the sample, so the design of the Faraday Cup took into consideration the fact that the electron beam is absorbed both in the fluence sensing element as well as in the outer jacket. A virtual instrument was developed using National Instruments development software to control the data acquisition process with the Faraday Cup and associated NIM electronics. Fluence measurements have been carried out in the energy range from 1 to 5 MeV. Examples of fluence measurements on semiconductor devices will be presented. Work partially supported through NASA grant NCC3-721 and KSU's Research Council.

  19. Modeling the effect of 1 MeV electron irradiation on the performance of n+-p-p+ silicon space solar cells

    NASA Astrophysics Data System (ADS)

    Hamache, Abdelghani; Sengouga, Nouredine; Meftah, Afak; Henini, Mohamed

    2016-06-01

    Energetic particles such as electrons and protons induce severe degradation on the performance of solar cells used to power satellites and space vehicles. This degradation is usually attributed to lattice damage in the active region of the solar cell. One of the phenomena observed in silicon solar cells exposed to 1 MeV electron irradiation is the anomalous degradation of the short circuit current. It initially decreases followed by a recovery before falling again with increasing electron fluence. This behavior is usually attributed to type conversion of the solar cell active region. The other figures of merit, on the other hand, decrease monotonically. In this work numerical simulator SCAPS (Solar Cell Capacitance Simulator) is used to elucidate this phenomenon. The current-voltage characteristics of a Si n+-p-p+ structure are calculated under air mass zero spectrum with the fluence of 1 MeV electrons as a variable parameter. The effect of irradiation on the solar cell is simulated by a set of defects of which the energy levels lie deep in energy gap of silicon (much larger than the characteristic thermal energy kT far from either the conduction or valence band). Although several types of deep levels are induced by irradiation including deep donors (exchange electrons mainly with the conduction band), deep acceptors (exchange electrons mainly with the valence band) and/or generation-recombination centers (exchange electrons with both the conduction and valence bands), it was found that, only one of them (the shallowest donor) is responsible for the anomalous degradation of the short circuit current. It will be also shown, by calculating the free charge carrier profile in the active region, that this behavior is not related to type conversion but to a lateral widening of the space charge region.

  20. Study the sensitivity of dose calculation in prism treatment planning system using Monte Carlo simulation of 6 MeV electron beam

    SciTech Connect

    Hardiansyah, D.; Haryanto, F.; Male, S.

    2014-09-30

    Prism is a non-commercial Radiotherapy Treatment Planning System (RTPS) develop by Ira J. Kalet from Washington University. Inhomogeneity factor is included in Prism TPS dose calculation. The aim of this study is to investigate the sensitivity of dose calculation on Prism using Monte Carlo simulation. Phase space source from head linear accelerator (LINAC) for Monte Carlo simulation is implemented. To achieve this aim, Prism dose calculation is compared with EGSnrc Monte Carlo simulation. Percentage depth dose (PDD) and R50 from both calculations are observed. BEAMnrc is simulated electron transport in LINAC head and produced phase space file. This file is used as DOSXYZnrc input to simulated electron transport in phantom. This study is started with commissioning process in water phantom. Commissioning process is adjusted Monte Carlo simulation with Prism RTPS. Commissioning result is used for study of inhomogeneity phantom. Physical parameters of inhomogeneity phantom that varied in this study are: density, location and thickness of tissue. Commissioning result is shown that optimum energy of Monte Carlo simulation for 6 MeV electron beam is 6.8 MeV. This commissioning is used R50 and PDD with Practical length (R{sub p}) as references. From inhomogeneity study, the average deviation for all case on interest region is below 5 %. Based on ICRU recommendations, Prism has good ability to calculate the radiation dose in inhomogeneity tissue.

  1. Photocarrier Radiometry for Noncontact Evaluation of Monocrystalline Silicon (c-Si) Solar Cell Irradiated by 1 MeV Electron Beams

    NASA Astrophysics Data System (ADS)

    Song, P.; Liu, J. Y.; Yuan, H. M.; Wang, F.; Wang, Y.

    2016-08-01

    In this paper, the monocrystalline silicon (c-Si) solar cell irradiated by 1 MeV electron beams was investigated using noncontact photocarrier radiometry (PCR). A theoretical 1D two-layer PCR model including the impedance effect of the p-n junction was used to characterize the transport properties (carrier lifetime, diffusion coefficient, and surface recombination velocities) of c-Si solar cells irradiated by 1 MeV electron beams with different fluences. The carrier transport parameters were derived by the best fit through PCR measurements. Furthermore, an Ev+0.56 eV trap was introduced into the band gap based on the minority carrier lifetime reduction. An I-V characteristic was obtained by both AFORS-HET simulation and experimental study, and the simulation results shows in good agreement with the experimental results. Moreover, the simulation and experiment results also indicate that the increase of fluences of electron beams results in the reduction of short-circuit current and open-circuit voltage.

  2. Study the sensitivity of dose calculation in prism treatment planning system using Monte Carlo simulation of 6 MeV electron beam

    NASA Astrophysics Data System (ADS)

    Hardiansyah, D.; Male, S.; Haryanto, F.

    2014-09-01

    Prism is a non-commercial Radiotherapy Treatment Planning System (RTPS) develop by Ira J. Kalet from Washington University. Inhomogeneity factor is included in Prism TPS dose calculation. The aim of this study is to investigate the sensitivity of dose calculation on Prism using Monte Carlo simulation. Phase space source from head linear accelerator (LINAC) for Monte Carlo simulation is implemented. To achieve this aim, Prism dose calculation is compared with EGSnrc Monte Carlo simulation. Percentage depth dose (PDD) and R50 from both calculations are observed. BEAMnrc is simulated electron transport in LINAC head and produced phase space file. This file is used as DOSXYZnrc input to simulated electron transport in phantom. This study is started with commissioning process in water phantom. Commissioning process is adjusted Monte Carlo simulation with Prism RTPS. Commissioning result is used for study of inhomogeneity phantom. Physical parameters of inhomogeneity phantom that varied in this study are: density, location and thickness of tissue. Commissioning result is shown that optimum energy of Monte Carlo simulation for 6 MeV electron beam is 6.8 MeV. This commissioning is used R50 and PDD with Practical length (Rp) as references. From inhomogeneity study, the average deviation for all case on interest region is below 5 %. Based on ICRU recommendations, Prism has good ability to calculate the radiation dose in inhomogeneity tissue.

  3. Homogeneous and stable p-type doping of graphene by MeV electron beam-stimulated hybridization with ZnO thin films

    SciTech Connect

    Song, Wooseok; Kim, Yooseok; Hwan Kim, Sung; Youn Kim, Soo; Cha, Myoung-Jun; Song, Inkyung; Jeon, Cheolho; Sung Jung, Dae; Lim, Taekyung; Lee, Sumi; Ju, Sanghyun; Chel Choi, Won; Wook Jung, Min; An, Ki-Seok; Park, Chong-Yun

    2013-02-04

    In this work, we demonstrate a unique and facile methodology for the homogenous and stable p-type doping of graphene by hybridization with ZnO thin films fabricated by MeV electron beam irradiation (MEBI) under ambient conditions. The formation of the ZnO/graphene hybrid nanostructure was attributed to MEBI-stimulated dissociation of zinc acetate dihydrate and a subsequent oxidation process. A ZnO thin film with an ultra-flat surface and uniform thickness was formed on graphene. We found that homogeneous and stable p-type doping was achieved by charge transfer from the graphene to the ZnO film.

  4. Distribution of the number of emitted electrons for MeV H[sup +]- and He[sup 2+]-ion impact on metals

    SciTech Connect

    Benka, O.; Schinner, A.; Fink, T. )

    1995-03-01

    The statistical distribution of the number of emitted electrons induced by MeV H[sup +] and He[sup 2+] impact on aluminum, copper, and gold targets was measured. The obtained results are very well represented by a Polya distribution. Based on a simplified theoretical picture the appearance of a Polya distribution in this context can be explained by cascade processes, which permits a quantitative estimation of the distributions in good agreement with the experiments for all investigated projectile-target combinations. The deviation from a Poisson distribution is given by the relative importance of cascade processes compared to projectile-induced processes.

  5. Electrical and photoelectric characteristics of structures based on InSe and GaSe layered semiconductors irradiated with 12.5-MeV electrons

    SciTech Connect

    Kovalyuk, Z. D. Politanska, O. A.; Sydor, O. N.; Maslyuk, V. T.

    2008-11-15

    The effect of irradiation with 12.5-MeV electrons on the electrical and photoelectric parameters of layered photoconverters based on p-InSe-n-InSe and p-GaSe-n-InSe structures is studied. The observed variations in the current-voltage characteristics, photoresponse spectra, open-circuit voltage, and short-circuit current are caused by the formation of point defects. The absence of pronounced changes in the characteristics of the homojunctions and heterojunctions even after irradiation at the highest dose makes it possible to recommend these junctions for use in the fabrication of radiation-resistant photodetectors.

  6. New readout and data-acquisition system in an electron-tracking Compton camera for MeV gamma-ray astronomy (SMILE-II)

    NASA Astrophysics Data System (ADS)

    Mizumoto, T.; Matsuoka, Y.; Mizumura, Y.; Tanimori, T.; Kubo, H.; Takada, A.; Iwaki, S.; Sawano, T.; Nakamura, K.; Komura, S.; Nakamura, S.; Kishimoto, T.; Oda, M.; Miyamoto, S.; Takemura, T.; Parker, J. D.; Tomono, D.; Sonoda, S.; Miuchi, K.; Kurosawa, S.

    2015-11-01

    For MeV gamma-ray astronomy, we have developed an electron-tracking Compton camera (ETCC) as a MeV gamma-ray telescope capable of rejecting the radiation background and attaining the high sensitivity of near 1 mCrab in space. Our ETCC comprises a gaseous time-projection chamber (TPC) with a micro pattern gas detector for tracking recoil electrons and a position-sensitive scintillation camera for detecting scattered gamma rays. After the success of a first balloon experiment in 2006 with a small ETCC (using a 10×10×15 cm3 TPC) for measuring diffuse cosmic and atmospheric sub-MeV gamma rays (Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment I; SMILE-I), a (30 cm)3 medium-sized ETCC was developed to measure MeV gamma-ray spectra from celestial sources, such as the Crab Nebula, with single-day balloon flights (SMILE-II). To achieve this goal, a 100-times-larger detection area compared with that of SMILE-I is required without changing the weight or power consumption of the detector system. In addition, the event rate is also expected to dramatically increase during observation. Here, we describe both the concept and the performance of the new data-acquisition system with this (30 cm)3 ETCC to manage 100 times more data while satisfying the severe restrictions regarding the weight and power consumption imposed by a balloon-borne observation. In particular, to improve the detection efficiency of the fine tracks in the TPC from ~10% to ~100%, we introduce a new data-handling algorithm in the TPC. Therefore, for efficient management of such large amounts of data, we developed a data-acquisition system with parallel data flow.

  7. 0.5 - 165 MeV proton and 102 - 312 keV electron injections during the 2006 December 13 SEP event

    NASA Astrophysics Data System (ADS)

    Aran, A.; Agueda, N.; Jacobs, C.; Lario, D.; Sanahuja, B.; Poedts, S.; Marsden, R. G.

    2010-12-01

    The last large solar energetic particle event of solar cycle 23 was observed on 2006 December 13. The origin of this event was associated with a X3.4 flare from AR10930 at S06W23 and a fast (> 1700 km/s) halo CME. A long-lasting type III and a metric type II radio burst were also recorded. We combine proton observations from ACE/EPAM, SOHO/ERNE and STEREO/IMPACT (24 energy channels from 0.5 to 165 MeV) to model the proton differential intensities measured during this event. We simulate both the propagation of the CME-driven shock (from 4 solar radii to 1 AU) and the transport of shock-accelerated protons along the upstream interplanetary magnetic field lines. Near-relativistic (102 - 312 keV) electron observations by ACE/EPAM during the early phase of the event are used to constrain the electron transport conditions along the field lines and deduce, via a Monte Carlo transport model, the electron injection profile close to the Sun. The best-fit electron injection profile shows one prompt component consistent with the timing and duration of both the radio type III and the hard X-ray bursts and a second delayed injection component timely associated with the type II radio burst. From the proton modelling we quantify the injection rate of shock accelerated protons and show that most of the > 50 MeV protons are injected when the shock is still close to the Sun (i.e. within 42 solar radii). We compare the inferred electron and proton injections and discuss the possible contribution of flare-related particles in the early phase of the event.

  8. Response of single junction GaAs/GaAs and GaAs/Ge solar cells to multiple doses of 1 MeV electrons

    NASA Technical Reports Server (NTRS)

    Meier, D. L.; Szedon, J. R.; Bartko, J.; Chung, M. A.

    1989-01-01

    A comparison of the radiation tolerance of MOCVD-grown GaAs cells and GaAs/Ge cells was undertaken using 1 MeV electrons. The GaAs/Ge cells are somewhat more tolerant of 1 MeV electron irradiation and more responsive to annealing than are the GaAs/GaAs cells examined in this study. However, both types of cells suffer a greater degradation in efficiency than has been observed in other recent studies. The reason for this is not certain, but it may be associated with an emitter thickness which appears to be greater than desired. The deep level transient spectroscopy (DLTS) spectra following irradiation are not significantly different for the GaAs/Ge and the GaAs/GaAs cells, with each having just two peaks. The annealing behavior of these peaks is also similar in the two samples examined. It appears that no penalty in radiation tolerance, and perhaps some benefit, is associated with fabricating MOCVD GaAs cells on Ge substrates rather than GaAs substrates.

  9. Effective atomic number and electron density of amino acids within the energy range of 0.122-1.330 MeV

    NASA Astrophysics Data System (ADS)

    More, Chaitali V.; Lokhande, Rajkumar M.; Pawar, Pravina P.

    2016-08-01

    Photon attenuation coefficient calculation methods have been widely used to accurately study the properties of amino acids such as n-acetyl-L-tryptophan, n-acetyl-L-tyrosine, D-tryptophan, n-acetyl-L-glutamic acid, D-phenylalanine, and D-threonine. In this study, mass attenuation coefficients (μm) of these amino acids for 0.122-, 0.356-, 0.511-, 0.662-, 0.884-, 1.170, 1.275-, 1.330-MeV photons are determined using the radio-nuclides Co57, Ba133, Cs137, Na22, Mn54, and Co60. NaI (Tl) scintillation detection system was used to detect gamma rays with a resolution of 8.2% at 0.662 MeV. The calculated attenuation coefficient values were then used to determine total atomic cross sections (σt), molar extinction coefficients (ε), electronic cross sections (σe), effective atomic numbers (Zeff), and effective electron densities (Neff) of the amino acids. Theoretical values were calculated based on the XCOM data. Theoretical and experimental values are found to be in a good agreement (error<5%). The variations of μm, σt, ε, σe, Zeff, and Neff with energy are shown graphically. The values of μm, σt, ε, σe are higher at lower energies, and they decrease sharply as energy increases; by contrast, Zeff and Neff were found to be almost constant.

  10. Effect of irradiation with MeV protons and electrons on the conductivity compensation and photoluminescence of moderately doped p-4H-SiC (CVD)

    SciTech Connect

    Kozlovski, V. V.; Lebedev, A. A. Bogdanova, E. V.; Seredova, N. V.

    2015-09-15

    The compensation of moderately doped p-4H-SiC samples grown by the chemical vapor deposition (CVD) method under irradiation with 0.9-MeV electrons and 15-MeV protons is studied. The experimentally measured carrier removal rates are 1.2–1.6 cm{sup –1} for electrons and 240–260 cm{sup –1} for protons. The dependence of the concentration of uncompensated acceptors and donors, measured in the study, demonstrates a linear decrease with increasing irradiation dose to the point of complete compensation. This run of the dependence shows that compensation of the samples is due to the transition of carriers to deep centers formed by primary radiation-induced defects. It is demonstrated that, in contrast to n-SiC (CVD), primary defects in the carbon sublattice of moderately doped p-SiC (CVD) only cannot account for the compensation process. In p-SiC, either primary defects in the silicon sublattice, or defects in both sublattices are responsible for conductivity compensation. Also, photoluminescence spectra are examined in relation to the irradiation dose.

  11. Beam-dump/diagnostics box for a 10-kA 50-MeV, 50-ns electron beam

    SciTech Connect

    White, J.M.; Fessenden, T.J.; Fontaine, R.A.; Harvey, A.R.; Paul, A.C.

    1983-03-09

    We have developed a dump for the ATA beam that consists of a series of carbon plates whose collective thickness totals approximately 1.5 ranges at 50 MeV. The energy dissipated in the plates is radiated to a water-cooled wall. The dump is designed to dissipate up to 175 kW of average power. A small hole along the axis of the plates forms a beamlet that passes through an energy analyzer. The analyzer consists of a 60/sup 0/ bending magnet and two high-sensitivity beam-current/position monitors. The ratio of the beamlet current to full current is used to estimate the beam emittance.

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

    SciTech Connect

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

    2011-11-15

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

  13. Modifications in the structural and optical properties of nanocrystalline CaWO4 induced by 8 MeV electron beam irradiation

    NASA Astrophysics Data System (ADS)

    Aloysius Sabu, N.; Priyanka, K. P.; Ganesh, Sanjeev; Varghese, Thomas

    2016-06-01

    In this article we report the post irradiation effects in the structural and optical properties of nanocrystalline calcium tungstate synthesized by chemical precipitation and heat treatment. The samples were subjected to different doses of high-energy electron beam obtained from an 8 MeV Microton. Investigations using X-ray diffraction, scanning electron microscopy and Raman spectra confirmed changes in particle size and structural parameters. However, no phase change was detected for irradiated samples. The stretching/compressive strain caused by high energy electrons is responsible for the slight shift in the XRD peaks of irradiated samples. Modifications in the morphology of different samples were confirmed by scanning electron microscopy. Ultraviolet-visible absorption studies showed variations in the optical band gap (4.08-4.25 eV) upon electron-beam irradiation. New photoluminescence behaviour in electron beam irradiated nanocrystalline CaWO4 was evidenced. A blue shift of the PL peak with increase in intensity was observed in all the irradiated samples.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  15. Microstructural Parameters in 8 MeV Electron-Irradiated BOMBYX MORI Silk Fibers by Wide-ANGLE X-Ray Scattering Studies (waxs)

    NASA Astrophysics Data System (ADS)

    Sangappa, Asha, S.; Sanjeev, Ganesh; Subramanya, G.; Parameswara, P.; Somashekar, R.

    2010-01-01

    The present work looks into the microstructural modification in electron irradiated Bombyx mori P31 silk fibers. The irradiation process was performed in air at room temperature using 8 MeV electron accelerator at different doses: 0, 25, 50 and 100 kGy. Irradiation of polymer is used to cross-link or degrade the desired component or to fix the polymer morphology. The changes in microstructural parameters in these natural polymer fibers have been computed using wide angle X-ray scattering (WAXS) data and employing line profile analysis (LPA) using Fourier transform technique of Warren. Exponential, Lognormal and Reinhold functions for the column length distributions have been used for the determination of crystal size, lattice strain and enthalpy parameters.

  16. Angular distributions of electrons of energy E sub e greater than 0.06 MeV in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Sentman, D. D.; Vanallen, J. A.

    1975-01-01

    The results of an angular distribution analysis of the electron intensity data recorded near Jupiter for the period from 26 November to 14 December 1973 are presented. The data were from three directional particle detectors with effective integral electron energy thresholds of 0.06, 0.55, and 5.0 Mev, respectively. It was found that the central core of the magnetosphere, within 12 Jupiter radii, is dominated by pitch angle distributions strongly peaked at alpha = 90 deg, while the region from 12 to 25 Jupiter radii shows bidirectional and approximately equal maxima at alpha = 0 and 180 deg. Bidirectional angular distributions in the magnetodisc out to the radius of the magnetopause strongly suggest quasi-trapping on closed field lines as the predominant situation. Substantial field aligned, unidirectional streaming was detected on only two occasions. No distinctive effects on angular distributions were discerned near the L-shells of satellites.

  17. Experiments investigating the generation and transport of 10--12 MeV, 30-kA, mm-size electron beams with linear inductive voltage adders

    SciTech Connect

    Mazarakis, M.G.; Poukey, J.W.; Maenchen, J.E.

    1997-06-01

    The authors present the design, analysis, and results of the high-brightness electron beam experiments currently under investigation at Sandia National Laboratories. The anticipated beam parameters are the following: 8--12 MeV, 35--50 kA, 30--60 ns FWHM, and 0.5-mm rms beam radius. The accelerators utilized are SABRE and HERMES III. Both are linear inductive voltage adders modified to higher impedance and fitted with magnetically immersed foil less electron diodes. In the strong 20--50 Tesla solenoidal magnetic field of the diode, mm-size electron beams are generated and propagated to a beam stop. The electron beam is field emitted from mm-diameter needle-shaped cathode electrode and is contained in a similar size envelop by the strong magnetic field. These extremely space charge dominated beams provide the opportunity to study beam dynamics and possible instabilities in a unique parameter space. The SABRE experiments are already completed and have produced 30-kA, 1.5-mm FWHM electron beams, while the HERMES-III experiments are on-going.

  18. AGILE as a particle detector: Magnetospheric measurements of 10-100 MeV electrons in L shells less than 1.2

    NASA Astrophysics Data System (ADS)

    Argan, A.; Piano, G.; Tavani, M.; Trois, A.

    2016-04-01

    We study the capability of the AGILE gamma ray space mission in detecting magnetospheric particles (mostly electrons) in the energy range 10-100 MeV. Our measurements focus on the inner magnetic shells with L ≲ 1.2 in the magnetic equator. The instrument characteristics and a quasi-equatorial orbit of ˜500 km altitude make it possible to address several important properties of the particle populations in the inner magnetosphere. We review the on board trigger logic and study the acceptance of the AGILE instrument for particle detection. We find that the AGILE effective geometric factor (acceptance) is R≃50 cm2 sr for particle energies in the range 10-100 MeV. Particle event reconstruction allows to determine the particle pitch angle with the local magnetic field with good accuracy. We obtain the pitch angle distributions for both the AGILE "pointing" phase (July 2007 to October 2009) and the "spinning" phase (November 2009 to present). In spinning mode, the whole range (0-180 degrees) is accessible every 7 min. We find a pitch angle distribution of the "dumbbell" type with a prominent depression near α = 90° which is typical of wave-particle resonant scattering and precipitation in the inner magnetosphere. Most importantly, we show that AGILE is not affected by solar particle precipitation events in the magnetosphere. The satellite trajectory intersects magnetic shells in a quite narrow range (1.0 ≲ L ≲ 1.2); AGILE then has a high exposure to a magnetospheric region potentially rich of interesting phenomena. The large particle acceptance in the 10-100 MeV range, the pitch angle determination capability, the L shell exposure, and the solar-free background make AGILE a unique instrument for measuring steady and transient particle events in the inner magnetosphere.

  19. High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun.

    PubMed

    Fu, Feichao; Liu, Shengguang; Zhu, Pengfei; Xiang, Dao; Zhang, Jie; Cao, Jianming

    2014-08-01

    A compact ultrafast electron diffractometer, consisting of an s-band 1.6 cell photocathode radio-frequency gun, a multi-function changeable sample chamber, and a sensitive relativistic electron detector, was built at Shanghai Jiao Tong University. High-quality single-shot transmission electron diffraction patterns have been recorded by scattering 2.5 MeV electrons off single crystalline gold and polycrystalline aluminum samples. The high quality diffraction pattern indicates an excellent spatial resolution, with the ratio of the diffraction ring radius over the ring rms width beyond 10. The electron pulse width is estimated to be about 300 fs. The high temporal and spatial resolution may open new opportunities in various areas of sciences. PMID:25173270

  20. High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun

    SciTech Connect

    Fu, Feichao; Liu, Shengguang; Zhu, Pengfei; Xiang, Dao Zhang, Jie; Cao, Jianming

    2014-08-15

    A compact ultrafast electron diffractometer, consisting of an s-band 1.6 cell photocathode radio-frequency gun, a multi-function changeable sample chamber, and a sensitive relativistic electron detector, was built at Shanghai Jiao Tong University. High-quality single-shot transmission electron diffraction patterns have been recorded by scattering 2.5 MeV electrons off single crystalline gold and polycrystalline aluminum samples. The high quality diffraction pattern indicates an excellent spatial resolution, with the ratio of the diffraction ring radius over the ring rms width beyond 10. The electron pulse width is estimated to be about 300 fs. The high temporal and spatial resolution may open new opportunities in various areas of sciences.

  1. Modification of the microstructure and electronic properties of rutile TiO2 thin films with 79 MeV Br ion irradiation

    NASA Astrophysics Data System (ADS)

    Rath, Haripriya; Dash, P.; Singh, U. P.; Avasthi, D. K.; Kanjilal, D.; Mishra, N. C.

    2015-12-01

    Modifications induced by 79 MeV Br ions in rutile titanium dioxide thin films, synthesized by dc magnetron sputtering are presented. Irradiations did not induce any new XRD peak corresponding to any other phase. The area and the width of the XRD peaks were considerably affected by irradiation, and peaks shifted to lower angles. But the samples retained their crystallinity at the highest fluence (1 × 1013 ions cm-2) of irradiation even though the electronic energy loss of 79 MeV Br ions far exceeds the reported threshold value for amorphization of rutile TiO2. Fitting of the fluence dependence of the XRD peak area to Poisson equation yielded the radius of ion tracks as 2.4 nm. Ion track radius obtained from the simulation based on the thermal spike model matches closely with that obtained from the fluence dependence of the area under XRD peaks. Williamson-Hall analysis of the XRD spectra indicated broadening and shifting of the peaks are a consequence of irradiation induced defect accumulation leading to microstrains, as was also indicated by Raman and UV-Visible absorption study.

  2. Spectroscopic Investigation of the Formation of Radiolysis By-Products By 13/9 MeV Linear Accelerator of Electrons (LAE) in Salt Solutions

    SciTech Connect

    Paviet-Hartmann, P.; Dziewinski, J.; Hartmann, T.; Marczak, S.; Lu, N.; Walthall, M.; Rafalski, A.; Zagorski, Z. P.

    2002-02-26

    In the near-field chemistry of a salt repository, the radiolytically-induced redox reactions in concentrated saline solution are of particular importance because the radiolysis of saline solutions results in oxidizing chlorine-containing species, which may oxidize actinide species to higher oxidation states. If the brines are irradiated, the solutions containing radiolytic species such as hypochlorite, hypochlorous acid or hydrogen peroxide, their pH and Eh may be altered. The oxidation and complexation states of actinides, which might be present in the salt brine, will change thus influencing their speciation and consequently their mobility. Furthermore, radiolytically formed oxidizing species such as ClO- or H2O2 may enhance the corrosion of the canister material. Therefore, radiation effects on salt brines must be integrated into the database, which described the chemical processes near a disposal site. Investigations in that context usually focus on the radiation chemistry of solid NaCl however our focus is on the radiolytic products, which are formed when salt brines are irradiated by a 10 MeV linear accelerator of electrons (LAE). We attempt to quantify the irradiation-induced formation of typical radiolysis by-products such as the hypochlorite ion (OCl-) by using a 13/9 MeV LAE with doses between 120 KGy to 216 KGy while monitoring the pH of the brine solutions.

  3. SPECTROSCOPIC INVESTIGATION OF THE FORMATION OF RADIOLYSIS BY-PRODUCTS BY 13/9 MEV LINEAR ACCELERATOR OF ELECTRONS (LAE) IN SALT SOLUTIONS.

    SciTech Connect

    Paviet-Hartmann, P.; Dziewinski, J. J.; Marczak, Stanislaw; Lu, N.; Walthall, M.

    2001-01-01

    In the near-field chemistry of a salt repository, the radiolytically-induced redox reactions in concentrated saline solution are of particular importance because the radiolysis of saline solutions results in oxidizing chlorine-containing species, which may oxidize actinide species to higher oxidation states. If the brines are irradiated, the solutions containing radiolytic species such as hypochlorite, hypochlorous acid or hydrogen peroxide, their pH and Eh may be altered. The oxidation and complexation states of actinides, which might be present in the salt brine, will change thus influencing their speciation and consequently their mobility. Furthermore, radiolytically formed oxidizing species such as ClO- or H2O2 may enhance the corrosion of the canister material. Therefore, radiation effects on salt brines must be integrated into the database, which described the chemical processes near a disposal site. Investigations in that context usually focus on the radiation chemistry of solid NaCl however our focus is on the radiolytic products, which are formed when salt brines are irradiated by a 10 MeV linear accelerator of electrons (LAE). We attempt to quantify the irradiation-induced formation of typical radiolysis by-products such as the hypochlorite ion (OCl-) by using a 13/9 MeV LAE with doses between 120 KGy to 216 KGy while monitoring the pH of the brine solutions

  4. Beam dynamics studies on the 100 MeV/100 kW electron linear accelerator for NSC KIPT neutron source

    NASA Astrophysics Data System (ADS)

    Pei, Shi-Lun; Chi, Yun-Long; Wang, Shu-Hong; Pei, Guo-Xi; Zhou, Zu-Sheng; Hou, Mi; Mykola, Ayzatskiy; Ivan, Karnaukhov; Volodymyr, Kushnir; Viktor, Mytrochenko; Andrey, Zelinsky

    2012-07-01

    We designed a 100 MeV/100 kW electron linear accelerator for NSC KIPT, which will be used to drive a neutron source on the basis of subcritical assembly. Beam dynamics studies have been conducted to reach the design requirements (E = 100 MeV, P = 100 kW, dE/E < 1% for 99% particles). In this paper, we will present the progress of the design and the dynamic simulation results. For high intensity and long beam pulse linear accelerators, the BBU effect is one big issue; special care has been taken in the accelerating structure design. To satisfy the energy spread requirement at the linac exit, the particles with large energy difference from the synchronous particle should be eliminated at a low energy stage to ease the design of the collimation system and radiation shielding. A dispersion free chicane with 4 bending magnets is introduced downstream of the 1st accelerating section; the unwanted particles will be collimated there.

  5. Monte Carlo simulation of runaway MeV electron breakdown with application to red sprites and terrestrial gamma ray flashes

    NASA Astrophysics Data System (ADS)

    Lehtinen, N. G.; Bell, T. F.; Inan, U. S.

    1999-11-01

    A three-dimensional Monte Carlo model of the uniform relativistic runaway electron breakdown in air in the presence of static electric and magnetic fields is used to calculate electron distribution functions, avalanche rates, and the direction and velocity of avalanche propagation. We also derive the conditions required for an electron with a given momentum to start an avalanche in the absence of a magnetic field. The results are compared to previously developed kinetic and analytical models and our own analytical estimates, and it is concluded that the rates used in many early models [e.g., Lehtinen et al., 1997; Taranenko and Roussel-Dupré, 1996; Yukhimuk et al., 1998; Roussel-Dupré et al., 1998] are overestimated by a factor of ~10. The Monte Carlo simulation results are applied to a fluid model of runaway electron beams in the middle atmosphere accelerated by quasi-electrostatic fields following a positive lightning stroke. In particular, we consider the case of lightning discharges which drain positive charge from remote regions of a laterally extensive (>100 km) thundercloud, using a Cartesian two-dimensional model. The resulting optical emission intensities in red sprites associated with the runaway electrons are found to be negligible compared to the emissions from thermal electrons heated in the conventional type of breakdown. The calculated gamma ray flux is of the same order as the terrestrial gamma ray flashes observed by the Burst and Transient Source Experiment detector on the Compton Gamma Ray Observatory.

  6. Investigation of solar cells fabricated on low-cost silicon sheet materials using 1 MeV electron irradiation

    NASA Technical Reports Server (NTRS)

    Kachare, A. H.; Hyland, S. L.; Garlick, G. F. J.

    1981-01-01

    The use of high energy electron irradiation is investigated as a controlled means to study in more detail the junction depletion layer processes of solar cells made on various low-cost silicon sheet materials. Results show that solar cells made on Czochralski grown silicon exhibit enhancement of spectral response in the shorter wavelength region when irradiated with high energy electrons. The base region damage can be reduced by subsequent annealing at 450 C which restores the degraded longer wavelength response, although the shorter wavelength enhancement persists. The second diode component of the cell dark forward bias current is also reduced by electron irradiation, while thermal annealing at 450 C without electron irradiation can also produce these same effects. Electron irradiation produces small changes in the shorter wavelength spectral responses and junction improvements in solar cells made on WEB, EFG, and HEM silicon. It is concluded that these beneficial effects on cell characteristics are due to the reduction of oxygen associated deep level recombination centers in the N(+) diffused layer and in the junction.

  7. Performance of candidate SEPS solar cells as a function of low temperature and low intensity exposure and 1 MeV electron irradiation

    NASA Astrophysics Data System (ADS)

    Whitaker, A. F.; Little, S. A.; Rives, C. J.; Wagner, P. E.

    1981-04-01

    The behavior of 144 high-performance shallow-junction silicon solar cells under conditions of low temperature and intensity was examined. The cells represented nine combinations of thickness, base resistivity, front surface texture, and rear surface treatment. At least 16 cells of each type were individually tested both as active elements under light levels between 0.04 and 1.0 solar constant and in the dark as passive rectifiers under external forward bias. One cell type was also irradiated with 1 MeV electrons up to 2.7 x 10 to the 15th e/sq cm. The inferior cells demonstrated high ohmic and/or non-ohmic shunting. No series resistance or Schottky barrier effects were observed. Fluences beyond 10 to the 13th e/sq cm lowered cell current, probably by increasing volume recombination.

  8. Performance of candidate SEPS solar cells as a function of low temperature and low intensity exposure and 1 MeV electron irradiation

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F.; Little, S. A.; Rives, C. J.; Wagner, P. E.

    1981-01-01

    The behavior of 144 high-performance shallow-junction silicon solar cells under conditions of low temperature and intensity was examined. The cells represented nine combinations of thickness, base resistivity, front surface texture, and rear surface treatment. At least 16 cells of each type were individually tested both as active elements under light levels between 0.04 and 1.0 solar constant and in the dark as passive rectifiers under external forward bias. One cell type was also irradiated with 1 MeV electrons up to 2.7 x 10 to the 15th e/sq cm. The inferior cells demonstrated high ohmic and/or non-ohmic shunting. No series resistance or Schottky barrier effects were observed. Fluences beyond 10 to the 13th e/sq cm lowered cell current, probably by increasing volume recombination.

  9. Studies on effective atomic numbers for photon energy absorption and electron density of some narcotic drugs in the energy range 1 keV-20 MeV

    NASA Astrophysics Data System (ADS)

    Gounhalli, Shivraj G.; Shantappa, Anil; Hanagodimath, S. M.

    2013-04-01

    Effective atomic numbers for photon energy absorption ZPEA,eff, photon interaction ZPI,eff and for electron density Nel, have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for narcotic drugs, such as Heroin (H), Cocaine (CO), Caffeine (CA), Tetrahydrocannabinol (THC), Cannabinol (CBD), Tetrahydrocannabivarin (THCV). The ZPEA,eff, ZPI,eff and Nel values have been found to change with energy and composition of the narcotic drugs. The energy dependence ZPEA,eff, ZPI,eff and Nel is shown graphically. The maximum difference between the values of ZPEA,eff, and ZPI,eff occurs at 30 keV and the significant difference of 2 to 33% for the energy region 5-100 keV for all drugs. The reason for these differences is discussed.

  10. Characteristics of the chemical forms of 11C, 13N, and 15O induced in air by the operation of a 100 MeV electron linear accelerator.

    PubMed

    Endo, A; Kikuchi, M; Izawa, S; Ikezawa, Y

    1995-01-01

    To characterize airborne radioactivity induced by the operation of high-energy accelerators, the fractions of aerosol and gaseous components, and the chemical forms of 11C, 13N, and 15O produced in the air of a target room of a 100 MeV electron linear accelerator were studied. Measurements of radioactivity using a particulate air sampling filter and a gas flow-through ionization chamber showed that more than 98% of 11C, 13N, and 15O were present as gaseous forms. Their chemical forms, detected by means of radio-gas chromatography, were 11C as CO2; 13N as N2 and NO; and 15O as O2 and NO. Machine operating conditions, which affect the compositions of the induced radionuclides and of their chemical forms, and the resulting effect on the estimation of internal doses are discussed. PMID:7989199

  11. Deflection of MeV electrons by self-generated magnetic fields in intense laser-solid interactions.

    PubMed

    Pérez, F; Kemp, A J; Divol, L; Chen, C D; Patel, P K

    2013-12-13

    We show that the interaction of relativistic-intensity, picosecond laser pulses with solid targets is affected by the reflected light through the strong currents and 10(4)  T magnetic fields it produces. Three-dimensional particle-in-cell simulations, with the axisymmetry broken by a small angle of incidence, show that these magnetic fields deflect the laser-accelerated electrons away from the incident laser axis. This directly impacts the interpretation of electron divergence and directionality in applications such as laser-driven ion acceleration or fast-ignition inertial fusion. PMID:24483668

  12. Bremsstrahlung and photoneutron production in a steel shield for 15-22-MeV clinical electron beams.

    PubMed

    Fujita, Yukio; Myojoyama, Atsushi; Saitoh, Hidetoshi

    2015-02-01

    The physical data regarding bremsstrahlung and neutrons produced in a steel shield by high-energy electron beams from a medical linear accelerator were investigated. These data are required to allow the accurate prediction of shielding performance for high-energy electron beams and in the design of radiotherapy facilities. A Monte Carlo code was used to develop Monte Carlo beam models for clinical electron beams and to directly simulate bremsstrahlung and secondary neutron production in a steel shield. The effective dose and dose equivalent of bremsstrahlung X rays and secondary neutrons outside a vault were determined using a realistic radiation source. The accuracy of Monte Carlo simulations was validated experimentally by comparing the measured and calculated physical quantities. In validating the Monte Carlo simulation, the measured and calculated values showed reasonable agreement, indicating that bremsstrahlung and photoneutron production and transport were simulated accurately. The bremsstrahlung X-ray dose was the main component of the total dose outside a vault. The secondary neutron dose was 1-20 % of the bremsstrahlung X-ray dose, but the neutron dose was also at a non-negligible level. The calculated neutron dose outside the vault differed from the McGinley's reported data. These results indicate that McGinley's method overestimates the neutron dose beyond the steel shield. The physical data used here will be useful in the accurate estimation of bremsstrahlung X-ray and neutron doses for high-energy electron beams. PMID:24821930

  13. Deep-level defects introduced by 1 MeV electron radiation in AlInGaP for multijunction space solar cells

    NASA Astrophysics Data System (ADS)

    Lee, H. S.; Yamaguchi, M.; Ekins-Daukes, N. J.; Khan, A.; Takamoto, T.; Agui, T.; Kamimura, K.; Kaneiwa, M.; Imaizumi, M.; Ohshima, T.; Itoh, H.

    2005-11-01

    Presented in this paper are 1 MeV electron irradiation effects on wide-band-gap (1.97 eV) (Al0.08Ga0.92)0.52In0.48P diodes and solar cells. The carrier removal rate estimated in p-AlInGaP with electron fluence is about 1 cm-1, which is lower than that in InP and GaAs. From high-temperature deep-level transient spectroscopy measurements, a deep-level defect center such as majority-carrier (hole) trap H2 (Eν+0.90+/-0.05 eV) was observed. The changes in carrier concentrations (Δp) and trap densities as a function of electron fluence were compared, and as a result the total introduction rate, 0.39 cm-1, of majority-carrier trap centers (H1 and H2) is different from the carrier removal rate, 1 cm-1, in p-AlInGaP. From the minority-carrier injection annealing (100 mA/cm2), the annealing activation energy of H2 defect is ΔE=0.60 eV, which is likely to be associated with a vacancy-phosphorus Frenkel pair (Vp-Pi). The recovery of defect concentration and carrier concentration in the irradiated p-AlInGaP by injection relates that a deep-level defect H2 acts as a recombination center as well as compensator center.

  14. Backward-propagating MeV electrons from 10{sup 18} W/cm{sup 2} laser interactions with water

    SciTech Connect

    Morrison, J. T.; Chowdhury, E. A.; Frische, K. D.; Ovchinnikov, V. M.; Feister, S. Orban, C.; Nees, J. A.; Freeman, R. R.; Roquemore, W. M.

    2015-04-15

    We present an experimental study of the generation of ∼MeV electrons opposite to the direction of laser propagation following the relativistic interaction at normal incidence of a ∼3 mJ, 10{sup 18} W/cm{sup 2} short pulse laser with a flowing 30 μm diameter water column target. Faraday cup measurements record hundreds of pC charge accelerated to energies exceeding 120 keV, and energy-resolved measurements of secondary x-ray emissions reveal an x-ray spectrum peaking above 800 keV, which is significantly higher energy than previous studies with similar experimental conditions and more than five times the ∼110 keV ponderomotive energy scale for the laser. We show that the energetic x-rays generated in the experiment result from backward-going, high-energy electrons interacting with the focusing optic, and vacuum chamber walls with only a small component of x-ray emission emerging from the target itself. We also demonstrate that the high energy radiation can be suppressed through the attenuation of the nanosecond-scale pre-pulse. These results are supported by 2D particle-in-cell simulations of the laser-plasma interaction, which exhibit beam-like backward-propagating MeV electrons.

  15. Effect of 8 MeV electron beam irradiation on the structural and optical properties of CeO{sub 2} nanoparticles

    SciTech Connect

    Babitha, K.K.; Priyanka, K.P.; Sreedevi, A.; Ganesh, S.; Varghese, Thomas

    2014-12-15

    The effect of 8 MeV electron beam irradiation on the structural and optical properties of cerium oxide nanoparticles was investigated. Ceria nanoparticles were synthesized by chemical precipitation method, and characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible, photoluminescence and Raman spectroscopy. Ultraviolet–visible absorption spectra, photoluminescence and Raman spectra of beam irradiated samples were modified, and shifted to blue region, which were attributed to quantum size effect. Systematic observations found that nonstoichiometry, defects and size reduction caused by beam irradiation have great influence on optical band gap, blue shift, photoluminescence and Raman band modifications. Moreover, electron beam irradiation is a suitable technique to enhance the structural and optical properties of nanoceria by controlling the particle size, which may lead to potentially useful technological applications. - Highlights: • Investigated effect of beam irradiation on CeO{sub 2} nanoparticles • Beam irradiation caused size reduction and surface modification. • It increases microstrain, decreases d-spacing and broadens XRD peaks. • It also modifies optical band gap, absorption, PL and Raman bands.

  16. Generation, control, and transport of a 19-MeV, 700-kA pulsed electron beam

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Poukey, J.W.; Skogmo, P.J.; Mikkelson, K.A. ); Welch, D.R. ); Mock, R.C. )

    1992-01-01

    We show experimentally and theoretically that the generation of the 13-TW Hermes III electron beam can be accurately monitored, and that the beam can be accurately directed onto a high-Z target to produce a wide variety of bremsstrahlung patterns. This control allows the study of radiation effects induced by gamma rays to be extended into new parameters regimes. Finally, we show that the beam can be stably transported in low-pressure gas cells.

  17. Dislocation loop nucleation and growth in zirconium-2.5 wt% niobium alloy during 1 MeV electron irradiation

    NASA Astrophysics Data System (ADS)

    Buckley, S. N.; Manthorpe, S. A.

    1980-05-01

    A high voltage electron microscope has been used to study loop formation in thin foils of Zr, Zircaloy and two Zr-Nb alloys. The effects of varying irradiation temperature and displacement dose were examined in the light of nucleation and growth theories. It was found that Nb solute enhanced loop densities by up to more than an order of magnitude but loop growth at 773 K was more than proportionately retarded so that total point defect precipitation is diminished. The temperature dependence of loop density corresponds to an activation energy 0.36 eV with <0.1 eV solute binding.

  18. Experimental and calculated radionuclide production by photonuclear reactions using Bremsstrahlung photons produced by 150 MeV electrons

    SciTech Connect

    Wunstorf, R.; Bugg, W.M.; Parks, C.C.; Gabriel, T.A.; Lewis, T.A.; Dickens, J.K.

    1994-12-31

    We have developed an experimental apparatus to study radionuclide production by photonuclear reactions. A nearly neutron-free bremsstrahlung beam was created by incident electron interactions with a tantalum radiator. We studied photonuclear reactions in different samples, including the elements Be, Na, Si, Cl, and Ge. Decay gamma rays from radionuclides having half lives > 2 min were analysed. Using the PICA code, we calculated the yield of radionuclides for silicon. We have observed and assigned a new gamma ray transition, of E({gamma}) = 1153 keV, to the decay of 6.6 min 29-Al.

  19. Experimental and calculated radionuclide production by photonuclear reactions using bremsstrahlung photons produced by 150 MeV electrons

    SciTech Connect

    Wunstorf, R.; Bugg, W.M.; Parks, C.C.; Gabriel, T.A.; Lewis, T.A.; Dickens, J.K.

    1995-02-01

    The authors have developed an experimental apparatus to study radionuclide production by photonuclear reactions. A nearly neutron free bremsstrahlung beam was created by incident electron interactions with a tantalum radiator. They studied photonuclear reactions in different samples, including the elements Be, Na, Si, Cl, and Ge. Decay gamma rays from radionuclides having half lives > 2 min were analysed. Using the PICA code, the authors calculated the yield of radionuclides for silicon. They have observed and assigned a new gamma ray transition, of E(y) = 1153 keV, to the decay of 6.6 min 29-Al.

  20. Auger electron spectroscopy study of alloy 718 and 304L stainless steel irradiated with 800 MeV protons

    NASA Astrophysics Data System (ADS)

    García-Mazarío, M.; Hernández-Mayoral, M.; Lancha, A. M.

    2001-07-01

    It is well known that radiation produces changes in materials microstructure such as formation of defects, dissolution and redistribution of secondary phases, precipitation of new phases, etc. and changes in the grain boundary microchemistry by a process known as radiation-induced segregation (RIS). This paper describes the grain boundary microchemical characterization of alloy 718 and 304L stainless steel irradiated with high-energy protons at Los Alamos Neutron Science Center (LANSCE), performed by means of Auger electron spectroscopy (AES). In addition, non-irradiated alloy 718 was characterized as reference. The Auger results showed that as a consequence of exposure to proton radiation, the changes observed in alloy 718 were the disappearance of the nickel and niobium rich grain boundaries precipitates and RIS of the major alloying elements (nickel to grain boundaries, and chromium and iron away from grain boundaries). On the other hand, in irradiated AISI 304L no differences were observed between intergranular and transgranular areas.

  1. Effect of 1.0 MeV electron irradiation on shunt resistance in Si-MINP solar cells

    NASA Technical Reports Server (NTRS)

    Anderson, Wayne A.; Banerjee, Sonali

    1987-01-01

    Shunt resistance from 100 K to 400 K is compared for diffused and ion implanted cells before and after irradiation. R sub sh decreases from greater than 10 to the 7th power omega-square cm for T less than 250 K to 10 to the 4th power omega-square cm at 400 K for non-irradiated diffused cells. Electron irradiation causes a more rapid decrease in R sub sh for T greater than 250 K. Ion implanted cells exhibit a similar trend except that R sub sh is significantly less for T less than 250 K and is more sensitive to irradiation at these low temperatures. The mechanism of R sub sh appears to be a combination of multistep tunneling and trapping - detrapping in the defect states of the semiconductor. Radiation serves to increase the density of these states to decrease R sub sh.

  2. Optical and electronic properties of sub-surface conducting layers in diamond created by MeV B-implantation at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Willems van Beveren, L. H.; Liu, R.; Bowers, H.; Ganesan, K.; Johnson, B. C.; McCallum, J. C.; Prawer, S.

    2016-06-01

    Boron implantation with in-situ dynamic annealing is used to produce highly conductive sub-surface layers in type IIa (100) diamond plates for the search of a superconducting phase transition. Here, we demonstrate that high-fluence MeV ion-implantation, at elevated temperatures avoids graphitization and can be used to achieve doping densities of 6 at. %. In order to quantify the diamond crystal damage associated with implantation Raman spectroscopy was performed, demonstrating high temperature annealing recovers the lattice. Additionally, low-temperature electronic transport measurements show evidence of charge carrier densities close to the metal-insulator-transition. After electronic characterization, secondary ion mass spectrometry was performed to map out the ion profile of the implanted plates. The analysis shows close agreement with the simulated ion-profile assuming scaling factors that take into account an average change in diamond density due to device fabrication. Finally, the data show that boron diffusion is negligible during the high temperature annealing process.

  3. Response of Microchannel Plate (MCP) Detectors to MeV Electrons: Beamline tests in support of Juno, JUICE, and Europa Mission UVS instrument investigations

    NASA Astrophysics Data System (ADS)

    Retherford, Kurt D.; Davis, Michael W.; Greathouse, Thomas K.; Gladstone, G. Randall; Steffl, Andrew J.; Grodent, Denis; Siegmund, Oswald H.W.

    2014-11-01

    The response of Microchannel Plate (MCP) detectors to far-UV photons is excellent. MCPs provide a photon-counting capability that is especially useful for high-quality stellar and solar occultation measurements. However, use of MCPs within the Jovian magnetosphere for UV measurements is hampered by their ~30% detection efficiency to energetic electrons and ~1% efficiency to γ-rays. High-Z shielding stops energetic electrons, but creates numerous secondary particles; γ-rays are the most important of these for MCPs. These detected particles are a noise background to the measured far-UV photon signal, and at particularly intense times their combination can approach detector global count rates of ~500 kHz when operating at nominal HV levels. To address the challenges presented by the intense radiation environment experienced during Europa encounters we performed electron beam radiation testing of the Juno-UVS flight spare cross-delay line (XDL) MCP in June 2012 at MIT’s High Voltage Research Laboratory (HVRL), and again in Nov. 2013 adding an atomic-layer deposition (ALD) coated test-MCP, to measure the detection efficiency and pulse height distribution characteristics for energetic electrons and γ-rays. A key result from this UVS-dedicated SwRI IR&D project is a detailed characterization of our XDL’s response to both particles (electrons and γ-rays) and photons as a function of HV level. These results provide confidence that good science data quality is achievable when operating at Europa closest approach and/or in orbit. Comparisons with in-flight data obtained with New Horizons Pluto-Alice MeV electron response measurements at Jupiter (Steffl et al., JGR, 2012), LRO-LAMP electron and proton event data, and Juno-UVS Earth proton-belt flyby data, and recent bench tests with radioactive sources at Sensor Sciences increase this confidence. We present a description of the test setup, quantitative results, and several lessons learned to help inform future beamline

  4. Deep-level defects introduced by 1 MeV electron radiation in AlInGaP for multijunction space solar cells

    SciTech Connect

    Lee, H.S.; Yamaguchi, M.; Ekins-Daukes, N. J.; Khan, A.; Takamoto, T.; Agui, T.; Kamimura, K.; Kaneiwa, M.; Imaizumi, M.; Ohshima, T.; Itoh, H.

    2005-11-01

    Presented in this paper are 1 MeV electron irradiation effects on wide-band-gap (1.97 eV) (Al{sub 0.08}Ga{sub 0.92}){sub 0.52}In{sub 0.48}P diodes and solar cells. The carrier removal rate estimated in p-AlInGaP with electron fluence is about 1 cm{sup -1}, which is lower than that in InP and GaAs. From high-temperature deep-level transient spectroscopy measurements, a deep-level defect center such as majority-carrier (hole) trap H2 (E{sub {nu}}+0.90{+-}0.05 eV) was observed. The changes in carrier concentrations ({delta}p) and trap densities as a function of electron fluence were compared, and as a result the total introduction rate, 0.39 cm{sup -1}, of majority-carrier trap centers (H1 and H2) is different from the carrier removal rate, 1 cm{sup -1}, in p-AlInGaP. From the minority-carrier injection annealing (100 mA/cm{sup 2}), the annealing activation energy of H2 defect is {delta}E=0.60 eV, which is likely to be associated with a vacancy-phosphorus Frenkel pair (V{sub p}-P{sub i}). The recovery of defect concentration and carrier concentration in the irradiated p-AlInGaP by injection relates that a deep-level defect H2 acts as a recombination center as well as compensator center.

  5. ''Yields of Radionuclides Created by Photonuclear Reactions on Be, C, Na, C1, and Ge, Using Bremsstrahlung of 150-MeV Electrons''

    SciTech Connect

    Dickens, J.K.

    2001-12-13

    The bremsstrahlung created by 150-MeV electrons impinging on a tantalum radiator was used to study photonuclear reactions on samples containing Be, C, Na, Cl and Ge. For Ge fifteen radioisotopes, ranging in half life between 2.6 min and 271 days, and in mass between 65 and 75, were obtained in sufficient amount to determine their yields quantitatively using known decay gamma-rays. Special equipment is described which was developed to create the bremsstrahlung using a beam-sharing mode, while minimizing the neutron flux on the sample. Relative production rates were determined. These were analyzed to provide absolute average cross sections for production of three reactions: <{sigma}> for {sup 35}Cl({gamma}, n) {sup 34}Cl{sup isom}- = 4.7 mb; <{sigma}> for {sup 70}Ge({gamma}, n){sup 69}Ge = 56 mb; and <{sigma}> for {sup 76}Ge({gamma}, n){sup 75}Ge = 53 mb, where the ({gamma}, n) values are averages over the giant resonances of the stable target isotopes.

  6. Effect of high current electron beam in a 30 MeV radio frequency linac for neutron-time-of-flight applications

    NASA Astrophysics Data System (ADS)

    Nayak, B.; Acharya, S.; Rajawat, R. K.; DasGupta, K.

    2016-01-01

    A high power pulsed radio frequency electron linac is designed by BARC, India to accelerate 30 MeV, 10 A, 10 ns beam for neutron-time-of-flight applications. It will be used as a neutron generator and will produce ˜1012-1013 n/s. It is essential to reduce the beam instability caused by space charge effect and the beam cavity interaction. In this paper, the wakefield losses in the accelerating section due to bunch of RMS (Root mean square) length 2 mm (at the gun exit) is analysed. Loss and kick factors are numerically calculated using CST wakefield solver. Both the longitudinal and transverse wake potentials are incorporated in beam dynamics code ELEGANT to find the transverse emittance growth of the beam propagating through the linac. Beam loading effect is examined by means of numerical computation carried out in ASTRA code. Beam break up start current has been estimated at the end of the linac which arises due to deflecting modes excited by the high current beam. At the end, transverse beam dynamics of such high current beam has been analysed.

  7. Spectral analysis of the effects of 1.7 MeV electron irradiation on the current transfer characteristic of cadmium telluride solar cells.

    PubMed

    Tian, Jin-Xiu; Zeng, Guang-Gen; He, Xu-Lin; Zhang, Jing-Quan; Wu, Li-Li; Li, Wei; Li, Bing; Wang, Wen-Wu; Feng, Liang-Huan

    2014-04-01

    The effects of device performance of 1.7 MeV electron irradiation on cadmium telluride polycrystalline thin film solar cells with the structure of anti-radiation glass/ITO/ZnO/CdS/CdTe/ZnTe/ZnTe : Cu/Ni have been studied. Light and dark I-V characteristics, dark C-V characteristics, quantum efficiency (QE), admittance spectrum (AS) and other testing methods were used to analyze cells performance such as the open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF) and conversion efficiency (eta). It was explored to find out the effects of irradiation on the current transfer characteristic of solar cells combined with the dark current density (Jo), diode ideal factor (A), quantum efficiency, carrier concentration and the depletion layer width. The decline in short-circuit current was very large and the efficiency of solar cells decreased obviously after irradiation. Reverse saturation current density increased, which indicates that p-n junction characteristics of solar cells were damaged, and diode ideal factor was almost the same, so current transport mechanism of solar cells has not changed. Quantum efficiency curves proved that the damage of solar cells' p-n junction influenced the collection of photo-generated carriers. Irradiation made carrier concentration reduce to 40.6%. The analyses have shown that. A new defect was induced by electron irradiation, whose position is close to 0.58 eV above the valence band in the forbidden band, and capture cross section is 1.78 x 10(-16) cm2. These results indicate that irradiation influences the generation of photo-generated carriers, increases the risk of the carrier recombination and the reverse dark current, and eventually makes the short-circuit current of solar cells decay. PMID:25007593

  8. 12 CFR 3.20 - Change in circumstances.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Change in circumstances. 3.20 Section 3.20 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY MINIMUM CAPITAL RATIOS; ISSUANCE OF DIRECTIVES Issuance of a Directive § 3.20 Change in circumstances. Upon a change in circumstances, a bank may request the Office to...

  9. Application of electron paramagnetic resonance imaging to the characterization of the Ultem(R) exposed to 1 MeV electrons. Correlation of radical density data to tiger code calculations

    SciTech Connect

    Suleman, N.K.

    1994-12-01

    A major long-term goal of the Materials Division at the NASA Langley Research Center is the characterization of new high-performance materials that have potential applications in the aircraft industry, and in space. The materials used for space applications are often subjected to a harsh and potentially damaging radiation environment. The present study constitutes the application of a novel technique to obtain reliable data for ascertaining the molecular basis for the resilience and durability of materials that have been exposed to simulated space radiations. The radiations of greatest concern are energetic electrons and protons, as well as galactic cosmic rays. Presently, the effects of such radiation on matter are not understood in their entirety. It is clear however, that electron radiation causes ionization and homolytic bond rupture, resulting in the formation of paramagnetic spin centers in the polymer matrices of the structural materials. Since the detection and structure elucidation of paramagnetic species are most readily accomplished using Electron Paramagnetic Resonance (EPR) Spectroscopy, the NASA LaRC EPR system was brought back on-line during the 1991 ASEE term. The subsequent 1992 ASEE term was devoted to the adaptation of the EPR core system to meet the requirements for EPR Imaging (EPRI), which provides detailed information on the spatial distribution of paramagnetic species in bulk media. The present (1994) ASEE term was devoted to the calibration of this EPR Imaging system, as well as to the application of this technology to study the effects of electron irradiation on Ultem(exp R), a high performance polymer which is a candidate for applications in aerospace. The Ultem was exposed to a dose of 2.4 x 10(exp 9) Rads (1-MeV energy/electron) at the LaRC electron accelerator facility. Subsequently, the exposed specimens were stored in liquid nitrogen, until immediately prior to analyses by EPRI.

  10. Proposal of balloon and satellite observations of MeV gammas using Electron Tracking Compton Camera for reaching a high sensitivity of 1 mCrab

    NASA Astrophysics Data System (ADS)

    Takada, Atsushi; Tanimori, Toru

    2016-04-01

    ETCC with a gas Time Projection Chamber (TPC) and pixel GSO scintillators, by measuring electron tracks precisely, provides both a strong background rejection by dE/dx of the track and well-defined 2-dimensional Point Spread Function (PDF) with better than several degrees by adding the arc direction of incident gammas (SPD: Scatter Plane Deviation) with the ARM (angular Resolution Measure) direction measured in standard Compton Camera (CC). In 2006 its background rejection was revealed by SMILE-I balloon experiment with 10cm-cubic ETCC using the dE/dx of tracks. In 2013, 30cm-cube-ETCC has been developed to catch gammas from Crab in next SMILE-II balloon with >5sigma detection for 4 hrs. Now its sensitivity has been improved to 10sigma by attaining the angular resolution of the track (SPD angle) to that determined by multiple scattering of the gas. Thus, we show the ability of ETCC to give a better significance by a factor of 10 than that of standard CCs having same detection area by electron tracking?and we have found that SPD is an essential to define the PSF of Compton imaging quantitatively. Such a well-defined PSF is, for the first time, able to provide reliable sensitivity in Compton imaging without assuming the use of optimization algorithm. These studies uncover the uncertainties of CCs from both points of view of the intense background and the difficulty of the definition of the PSF, and overcome the above problems. Based on this technology, SMILE-II with 3atm CF4 gas is expected to provide a 5times better sensitivity than COMPTEL in one month balloon, and 4modules of 50cm-cube ETCCs would exceed over 10^-12 erg/cm^2s^1 (1mCrab) in satellite. Here we summarize the performance of the ETCC and new astrophysics opened in near future by high sensitive observation of MeV gamma-rays.

  11. Application of electron paramagnetic resonance imaging to the characterization of the Ultem(R) exposed to 1 MeV electrons. Correlation of radical density data to tiger code calculations

    NASA Astrophysics Data System (ADS)

    Suleman, Naushadalli K.

    1994-12-01

    A major long-term goal of the Materials Division at the NASA Langley Research Center is the characterization of new high-performance materials that have potential applications in the aircraft industry, and in space. The materials used for space applications are often subjected to a harsh and potentially damaging radiation environment. The present study constitutes the application of a novel technique to obtain reliable data for ascertaining the molecular basis for the resilience and durability of materials that have been exposed to simulated space radiations. The radiations of greatest concern are energetic electrons and protons, as well as galactic cosmic rays. Presently, the effects of such radiation on matter are not understood in their entirety. It is clear however, that electron radiation causes ionization and homolytic bond rupture, resulting in the formation of paramagnetic spin centers in the polymer matrices of the structural materials. Since the detection and structure elucidation of paramagnetic species are most readily accomplished using Electron Paramagnetic Resonance (EPR) Spectroscopy, the NASA LaRC EPR system was brought back on-line during the 1991 ASEE term. The subsequent 1992 ASEE term was devoted to the adaptation of the EPR core system to meet the requirements for EPR Imaging (EPRI), which provides detailed information on the spatial distribution of paramagnetic species in bulk media. The present (1994) ASEE term was devoted to the calibration of this EPR Imaging system, as well as to the application of this technology to study the effects of electron irradiation on Ultem(exp R), a high performance polymer which is a candidate for applications in aerospace. The Ultem was exposed to a dose of 2.4 x 10(exp 9) Rads (1-MeV energy/electron) at the LaRC electron accelerator facility. Subsequently, the exposed specimens were stored in liquid nitrogen, until immediately prior to analyses by EPRI. The intensity and dimensions of the EPR Images that

  12. Application of electron paramagnetic resonance imaging to the characterization of the Ultem(R) exposed to 1 MeV electrons. Correlation of radical density data to tiger code calculations

    NASA Technical Reports Server (NTRS)

    Suleman, Naushadalli K.

    1994-01-01

    A major long-term goal of the Materials Division at the NASA Langley Research Center is the characterization of new high-performance materials that have potential applications in the aircraft industry, and in space. The materials used for space applications are often subjected to a harsh and potentially damaging radiation environment. The present study constitutes the application of a novel technique to obtain reliable data for ascertaining the molecular basis for the resilience and durability of materials that have been exposed to simulated space radiations. The radiations of greatest concern are energetic electrons and protons, as well as galactic cosmic rays. Presently, the effects of such radiation on matter are not understood in their entirety. It is clear however, that electron radiation causes ionization and homolytic bond rupture, resulting in the formation of paramagnetic spin centers in the polymer matrices of the structural materials. Since the detection and structure elucidation of paramagnetic species are most readily accomplished using Electron Paramagnetic Resonance (EPR) Spectroscopy, the NASA LaRC EPR system was brought back on-line during the 1991 ASEE term. The subsequent 1992 ASEE term was devoted to the adaptation of the EPR core system to meet the requirements for EPR Imaging (EPRI), which provides detailed information on the spatial distribution of paramagnetic species in bulk media. The present (1994) ASEE term was devoted to the calibration of this EPR Imaging system, as well as to the application of this technology to study the effects of electron irradiation on Ultem(exp R), a high performance polymer which is a candidate for applications in aerospace. The Ultem was exposed to a dose of 2.4 x 10(exp 9) Rads (1-MeV energy/electron) at the LaRC electron accelerator facility. Subsequently, the exposed specimens were stored in liquid nitrogen, until immediately prior to analyses by EPRI. The intensity and dimensions of the EPR Images that

  13. Relativistic (e > 0.6, > 2.0, and > 4.0 MeV) Electron Acceleration at Geosynchronous Orbit during High-intensity, Long-duration, Continuous AE Activity (HILDCAA) Events

    NASA Astrophysics Data System (ADS)

    Hajra, Rajkumar; Tsurutani, Bruce T.; Echer, Ezequiel; Gonzalez, Walter D.; Santolik, Ondrej

    2015-01-01

    Radiation-belt relativistic (E > 0.6, > 2.0, and > 4.0 MeV) electron acceleration is studied for solar cycle 23 (1995-2008). High-intensity, long-duration, continuous AE activity (HILDCAA) events are considered as the basis of the analyses. All of the 35 HILDCAA events under study were found to be characterized by flux enhancements of magnetospheric relativistic electrons of all three energies compared to the pre-event flux levels. For the E > 2.0 MeV electron fluxes, enhancement of >50% occurred during 100% of HILDCAAs. Cluster-4 passes were examined for electromagnetic chorus waves in the 5 < L < 10 and 0 < MLT < 12 region when wave data were available. Fully 100% of these HILDCAA cases were associated with enhanced whistler-mode chorus waves. The enhancements of E > 0.6, > 2.0, and > 4.0 MeV electrons occurred ~1.0 day, ~1.5 days, and ~2.5 days after the statistical HILDCAA onset, respectively. The statistical acceleration rates for the three energy ranges were ~1.8 × 105, 2.2 × 103, and 1.0 × 101 cm-2 s-1 sr-1 d-1, respectively. The relativistic electron-decay timescales were determined to be ~7.7, 5.5, and 4.0 days for the three energy ranges, respectively. The HILDCAAs were divided into short-duration (D <= 3 days) and long-duration (D > 3 days) events to study the dependence of relativistic electron variation on HILDCAA duration. For long-duration events, the flux enhancements during HILDCAAs with respect to pre-event fluxes were ~290%, 520%, and 82% for E > 0.6, > 2.0, and > 4.0 MeV electrons, respectively. The enhancements were ~250%, 400%, and 27% respectively, for short-duration events. The results are discussed with respect to the current understanding of radiation-belt dynamics.

  14. A comparison of MCNP4C electron transport with ITS 3.0 and experiment at incident energies between 100 keV and 20 MeV: influence of voxel size, substeps and energy indexing algorithm

    NASA Astrophysics Data System (ADS)

    Schaart, Dennis R.; Jansen, Jan Th M.; Zoetelief, Johannes; de Leege, Piet F. A.

    2002-05-01

    The condensed-history electron transport algorithms in the Monte Carlo code MCNP4C are derived from ITS 3.0, which is a well-validated code for coupled electron-photon simulations. This, combined with its user-friendliness and versatility, makes MCNP4C a promising code for medical physics applications. Such applications, however, require a high degree of accuracy. In this work, MCNP4C electron depth-dose distributions in water are compared with published ITS 3.0 results. The influences of voxel size, substeps and choice of electron energy indexing algorithm are investigated at incident energies between 100 keV and 20 MeV. Furthermore, previously published dose measurements for seven beta emitters are simulated. Since MCNP4C does not allow tally segmentation with the *F8 energy deposition tally, even a homogeneous phantom must be subdivided in cells to calculate the distribution of dose. The repeated interruption of the electron tracks at the cell boundaries significantly affects the electron transport. An electron track length estimator of absorbed dose is described which allows tally segmentation. In combination with the ITS electron energy indexing algorithm, this estimator appears to reproduce ITS 3.0 and experimental results well. If, however, cell boundaries are used instead of segments, or if the MCNP indexing algorithm is applied, the agreement is considerably worse.

  15. Study of the degradation of short-circuit current and the open-circuit tension of spatial solar cells as a function of the fluency of 1MeV electrons

    NASA Astrophysics Data System (ADS)

    Veissid, N.

    1984-12-01

    Results of a study of the degradation of short circuit current and the tension of open circuitry of spatial solar cells as a function of the fluency of 1 MeV electrons are presented. The theory of the degradation of solar cells by ionizing radiation is discussed as it relates to the diminution of the length of diffusion and variations in short circuit current and open circuit tension by irradiation. Parameters were determined which could be adjusted as curves of ISC and VOC, as a function of the fluency of 1 MeV electrons, and spatial solar cells (type n/p) with and without a retrosuperficial electrical field and retroreflector contact. A double exponential model and iterative methods were used which permitted the determination of the values of series resistance, saturation current of the mechanism of diffusion, and saturation current of the recombination process. An empiric equation is proposed for the degradation of VOC by solar cell irradiation with retroreflector contact.

  16. Annual Cosmic Ray Spectra from 250 MeV up to 1.6 GeV from 1995 - 2014 Measured with the Electron Proton Helium Instrument onboard SOHO

    NASA Astrophysics Data System (ADS)

    Kühl, P.; Gómez-Herrero, R.; Heber, B.

    2016-03-01

    The solar modulation of galactic cosmic rays (GCR) can be studied in detail by examining long-term variations of the GCR energy spectrum ( e.g. on the scales of a solar cycle). With almost 20 years of data, the Electron Proton Helium INstrument (EPHIN) onboard the SOlar and Heliospheric Observatory (SOHO) is well suited for this kind of investigation. Although the design of the instrument is optimised to measure proton and helium isotope spectra up to 50 MeV nucleon^{-1}, the capability exists to determine proton energy spectra from 250 MeV up to above 1.6 GeV. Therefore we developed a sophisticated inversion method to calculate such proton spectra. The method relies on a GEANT4 Monte Carlo simulation of the instrument and a simplified spacecraft model that calculates the energy-response function of EPHIN for electrons, protons, and heavier ions. For validation purposes, proton spectra based on this method are compared to various balloon missions and space instrumentation. As a result we present annual galactic cosmic-ray spectra from 1995 to 2014.

  17. Characterization of 2 MeV, 4 MeV, 6 MeV and 18 MeV buildup caps for use with a 0.6 cubic centimeter thimble ionization chamber

    SciTech Connect

    Salyer, R.L.; VanDenburg, J.W.; Prinja, A.K.; Kirby, T.; Busch, R.; Hong-Nian Jow

    1996-07-01

    The purpose of this research is to characterize existing 2 MeV, 4 MeV and 6 MeV buildup caps, and to determine if a buildup cap can be made for the 0.6 cm{sup 3} thimble ionization chamber that will accurately measure exposures in a high-energy photon radiation field. Two different radiation transport codes were used to computationally characterize existing 2 MeV, 4 MeV, and 6 MeV buildup caps for a 0.6 cm{sup 3} active volume thimble ionization chamber: ITS, The Integrated TIGER Series of Coupled Electron-Photon Monte Carlo Transport Codes; and CEPXS/ONEDANT, A One-Dimensional Coupled Electron-Photon Discrete Ordinates Code Package. These codes were also used to determine the design characteristics of a buildup cap for use in the 18 MeV photon beam produced by the 14 TW pulsed power HERMES-III electron accelerator. The maximum range of the secondary electron, the depth at which maximum dose occurs, and the point where dose and collision kerma are equal have been determined to establish the validity of electronic equilibrium. The ionization chamber with the appropriate buildup cap was then subjected to a 4 MeV and a 6 MeV bremmstrahlung radiation spectrum to determine the detector response.

  18. Simulation of a two step TGF ignition above cloudtops with MeV electron input fluxes generated in the electric fields of lightning streamers

    NASA Astrophysics Data System (ADS)

    Connell, P. H.

    2014-12-01

    The origin of high energy electrons which contribute to the Runaway Electron Avalanche of a TGF are not precisely known, or yet observed, though the most obvious source would seem to be the products of cosmic ray showers, or electron avalanches generated in the high electric field near the tips of lightning leaders. With our TGF simulation software package LEPTRACK we can easily create all kinds of electric field geometries and are investigating the second scenario with combinations of lightning leader and streamer micro-fields producing electron avalanches, which may or may not be runaway, which are then input to the macro-fields expected at or above thunderstorm cloudtops.We will present the detailed evolution of photon, electron, neutron/proton and ionization density fields resulting to demonstrate the possibility that TGF origin is not one of the two models currently proposed but may be a combination of both.

  19. Demonstration of Single-Shot Picosecond Time-Resolved MeV Electron Imaging Using a Compact Permanent Magnet Quadrupole Based Lens.

    PubMed

    Cesar, D; Maxson, J; Musumeci, P; Sun, Y; Harrison, J; Frigola, P; O'Shea, F H; To, H; Alesini, D; Li, R K

    2016-07-01

    We present the results of an experiment where a short focal length (∼1.3  cm), permanent magnet electron lens is used to image micron-size features (of a metal sample) with a single shot from an ultrahigh brightness picosecond-long 4 MeV electron beam emitted by a radio-frequency photoinjector. Magnification ratios in excess of 30× were obtained using a triplet of compact, small gap (3.5 mm), Halbach-style permanent magnet quadrupoles with nearly 600  T/m field gradients. These results pave the way towards single-shot time-resolved electron microscopy and open new opportunities in the applications of high brightness electron beams. PMID:27447510

  20. Backward-propagating MeV electrons in ultra-intense laser interactions: Standing wave acceleration and coupling to the reflected laser pulse

    SciTech Connect

    Orban, Chris Feister, Scott; Morrison, John T.; Chowdhury, Enam A.; Nees, John A.; Frische, Kyle; Roquemore, W. M.

    2015-02-15

    Laser-accelerated electron beams have been created at a kHz repetition rate from the reflection of intense (∼10{sup 18 }W/cm{sup 2}), ∼40 fs laser pulses focused on a continuous water-jet in an experiment at the Air Force Research Laboratory. This paper investigates Particle-in-Cell simulations of the laser-target interaction to identify the physical mechanisms of electron acceleration in this experiment. We find that the standing-wave pattern created by the overlap of the incident and reflected laser is particularly important because this standing wave can “inject” electrons into the reflected laser pulse where the electrons are further accelerated. We identify two regimes of standing wave acceleration: a highly relativistic case (a{sub 0} ≥ 1), and a moderately relativistic case (a{sub 0} ∼ 0.5) which operates over a larger fraction of the laser period. In previous studies, other groups have investigated the highly relativistic case for its usefulness in launching electrons in the forward direction. We extend this by investigating electron acceleration in the specular (back reflection) direction and over a wide range of intensities (10{sup 17}–10{sup 19 }W cm{sup −2})

  1. Energy-dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions

    NASA Astrophysics Data System (ADS)

    Reeves, Geoffrey D.; Friedel, Reiner H. W.; Larsen, Brian A.; Skoug, Ruth M.; Funsten, Herbert O.; Claudepierre, Seth G.; Fennell, Joseph F.; Turner, Drew L.; Denton, Mick H.; Spence, Harlan E.; Blake, J. Bernard; Baker, Daniel N.

    2016-01-01

    We present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are more common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of "slot filling" events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy- and L shell-dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.

  2. A beamline design and data acquisition with the 20-MeV, 20-ps electron beam for the higher-order mode studies of the APS SR-rf cavities

    SciTech Connect

    Song, J.; Nassiri, A.; Daly, R.

    1993-01-01

    A beamline has been designed and assembled to use the ANL Chemistry Division 20-MeV electron linac for the testing of higher-order mode excitation and damping in rf cavities. The beamline consists of two sections (a beam collimating section with a 1.5 inches-OD vacuum line, and a cavity test section with a 3 inches-OD vacuum line), separated by two double aluminum foil windows. The beam diagnostics consist of a stripline beam position monitor, integrating current transformers, fluorescent screens, and a Faraday cup. EPICS (Experimental Physics and Industrial Control System) is used for beamline control, monitoring, and data acquisition. Also described is the diagnostic system used for beam image capture and analysis using EPICS-controlled hardware and PV-WAVE software. The rf cavity measurement will be described in a separate paper.

  3. A beamline design and data acquisition with the 20-MeV, 20-ps electron beam for the higher-order mode studies of the APS SR-rf cavities

    SciTech Connect

    Song, J.; Nassiri, A.; Daly, R.

    1993-07-01

    A beamline has been designed and assembled to use the ANL Chemistry Division 20-MeV electron linac for the testing of higher-order mode excitation and damping in rf cavities. The beamline consists of two sections (a beam collimating section with a 1.5 inches-OD vacuum line, and a cavity test section with a 3 inches-OD vacuum line), separated by two double aluminum foil windows. The beam diagnostics consist of a stripline beam position monitor, integrating current transformers, fluorescent screens, and a Faraday cup. EPICS (Experimental Physics and Industrial Control System) is used for beamline control, monitoring, and data acquisition. Also described is the diagnostic system used for beam image capture and analysis using EPICS-controlled hardware and PV-WAVE software. The rf cavity measurement will be described in a separate paper.

  4. Interaction of Electron Neutrinos with {sup 56}Fe in the LSD for E{sub {nu}{sub e}} {<=} 50 MeV

    SciTech Connect

    Gaponov, Yu.V.; Ryazhskaya, O.G.; Semenov, S.V.

    2004-11-01

    The neutrino pulses detected by the LSD (Liquid Scintillator Detector) on February 23, 1987, are analyzed on the basis of a two-stage model of supernova explosion. The number of events due to the electron-neutrino interaction with {sup 56}Fe in the LSD is calculated. The obtained number of signals is in agreement with experimental data.

  5. Energy-dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions

    DOE PAGESBeta

    Reeves, Geoffrey D.; Friedel, Reiner H. W.; Larsen, Brian A.; Skoug, Ruth M.; Funsten, Herbert O.; Claudepierre, Seth G.; Fennell, Joseph F.; Turner, Drew L.; Denton, Mick H.; Spence, Harlan E.; et al

    2016-01-28

    Here, we present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are moremore » common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of “slot filling” events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy- and L shell-dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.« less

  6. Roos and NACP-02 ion chamber perturbations and water-air stopping-power ratios for clinical electron beams for energies from 4 to 22 MeV.

    PubMed

    Bailey, M; Shipley, D R; Manning, J W

    2015-02-01

    Empirical fits are developed for depth-compensated wall- and cavity-replacement perturbations in the PTW Roos 34001 and IBA / Scanditronix NACP-02 parallel-plate ionisation chambers, for electron beam qualities from 4 to 22 MeV for depths up to approximately 1.1 × R₅₀,D. These are based on calculations using the Monte Carlo radiation transport code EGSnrc and its user codes with a full simulation of the linac treatment head modelled using BEAMnrc. These fits are used with calculated restricted stopping-power ratios between air and water to match measured depth-dose distributions in water from an Elekta Synergy clinical linear accelerator at the UK National Physical Laboratory. Results compare well with those from recent publications and from the IPEM 2003 electron beam radiotherapy Code of Practice. PMID:25586026

  7. Studies on mass attenuation coefficient, effective atomic number and electron density of some amino acids in the energy range 0.122-1.330 MeV

    NASA Astrophysics Data System (ADS)

    Pawar, Pravina P.; Bichile, Govind K.

    2013-11-01

    The total mass attenuation coefficients of some amino acids, such as Glycine (C2H5NO2), DL-Alanine (C3H7NO2), Proline (C5H9NO2), L-Leucine (C6H13NO2 ), L-Arginine (C6H14N4O2) and L-Arginine Monohydrochloride (C6H15ClN4O2), were measured at 122, 356, 511, 662, 1170, 1275 and 1330 keV photon energies using a well-collimated narrow beam good geometry set-up. The gamma rays were detected using NaI (Tl) scintillation detection system with a resolution of 10.2% at 662 keV. The attenuation coefficient data were then used to obtain the effective atomic numbers (Zeff) and effective electron densities (Neff) of amino acids. It was observed that the effective atomic number (Zeff) and effective electron densities (Neff) tend to be almost constant as a function of gamma-ray energy. The results show that, the experimental values of mass attenuation coefficients, effective atomic numbers and effective electron densities are in good agreement with the theoretical values with less than 1% error.

  8. Evidence of transient species occurring in the reduction process of trivalent lanthanides under 2.5 MeV electron irradiation by in situ cathodoluminescence and time-resolved photoluminescence

    SciTech Connect

    Ollier, N.; Boizot, B.; L'Henoret, P.; Guillous, S.; Petite, G.

    2009-06-01

    In situ cathodoluminescence and time-resolved photoluminescence measurements were carried out on Sm-doped glasses during a 2.5 MeV electron irradiation. These experiments allow characterizing more precisely the mechanisms operating under irradiation and more specifically the reduction processes of Sm{sup 3+} to Sm{sup 2+} ions. Sm{sup 2+} emission lines appear in the first steps of the irradiation, however, the {sup 5}D{sub 0}->{sup 7}F{sub 0-2} emission lines of Sm{sup 2+} were not observed on the cathodoluminescence spectrum. Moreover, two sites of Sm{sup 2+} have been evidenced in the glasses; the formation of each species is clearly different. Relaxation processes of Sm{sup 3+} and Sm{sup 2+} leads to consider the existence of different transient states of Sm{sup 3+} and Sm{sup 2+} species which are annealed after irradiation. We propose some synthetic schemes of the reduction mechanisms produced during the irradiation.

  9. Conceptual design of industrial free electron laser using superconducting accelerator

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Ulyanov, Yu.N.

    1995-12-31

    Paper presents conceptual design of free electron laser (FEL) complex for industrial applications. The FEL complex consists of three. FEL oscillators with the optical output spanning the infrared (IR) and ultraviolet (UV) wave-lengths ({lambda} = 0.3...20 {mu}m) and with the average output power 10 - 20 kW. The driving beam for the FELs is produced by a superconducting accelerator. The electron beam is transported to the FELs via three beam lines (125 MeV and 2 x 250 MeV). Peculiar feature of the proposed complex is a high efficiency of the. FEL oscillators, up to 20 %. This becomes possible due to the use of quasi-continuous electron beam and the use of the time-dependent undulator tapering.

  10. 41 CFR 102-3.20 - How does this part meet the needs of its audience?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the needs of its audience? 102-3.20 Section 102-3.20 Public Contracts and Property Management Federal...? § 102-3.20 How does this part meet the needs of its audience? This Federal Advisory Committee Management part meets the general and specific needs of its audience by addressing the following issues...

  11. 41 CFR 102-3.20 - How does this part meet the needs of its audience?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the needs of its audience? 102-3.20 Section 102-3.20 Public Contracts and Property Management Federal...? § 102-3.20 How does this part meet the needs of its audience? This Federal Advisory Committee Management part meets the general and specific needs of its audience by addressing the following issues...

  12. 17 CFR 210.3-20 - Currency for financial statements of foreign private issuers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... statements of foreign private issuers. 210.3-20 Section 210.3-20 Commodity and Securities Exchanges... Statements § 210.3-20 Currency for financial statements of foreign private issuers. (a) A foreign private... date shall be used if materially different. (c) If the financial statements of a foreign private...

  13. 17 CFR 210.3-20 - Currency for financial statements of foreign private issuers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... statements of foreign private issuers. 210.3-20 Section 210.3-20 Commodity and Securities Exchanges... Statements § 210.3-20 Currency for financial statements of foreign private issuers. (a) A foreign private... date shall be used if materially different. (c) If the financial statements of a foreign private...

  14. 41 CFR 102-3.20 - How does this part meet the needs of its audience?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the needs of its audience? 102-3.20 Section 102-3.20 Public Contracts and Property Management Federal...? § 102-3.20 How does this part meet the needs of its audience? This Federal Advisory Committee Management part meets the general and specific needs of its audience by addressing the following issues...

  15. 41 CFR 102-3.20 - How does this part meet the needs of its audience?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the needs of its audience? 102-3.20 Section 102-3.20 Public Contracts and Property Management Federal...? § 102-3.20 How does this part meet the needs of its audience? This Federal Advisory Committee Management part meets the general and specific needs of its audience by addressing the following issues...

  16. 41 CFR 102-3.20 - How does this part meet the needs of its audience?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... the needs of its audience? 102-3.20 Section 102-3.20 Public Contracts and Property Management Federal...? § 102-3.20 How does this part meet the needs of its audience? This Federal Advisory Committee Management part meets the general and specific needs of its audience by addressing the following issues...

  17. 7 CFR 3.20 - Standards for suspending or terminating collection activities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... activities. 3.20 Section 3.20 Agriculture Office of the Secretary of Agriculture DEBT MANAGEMENT Standards for the Administrative Collection and Compromise of Claims § 3.20 Standards for suspending or terminating collection activities. An agency shall follow the standards set forth in 31 CFR part 903 for...

  18. Time-dependent 2.2 MeV and 0.5 MeV lines from solar flares

    NASA Technical Reports Server (NTRS)

    Wang, H. T.; Ramaty, R.

    1975-01-01

    The time dependences of the 2.2 MeV and 0.51 MeV gamma ray lines from solar flares are calculated and the results are compared with observations of the 1972, August 4 and 7 flares. Time lag between the nuclear reactions and the formation of these two lines are caused, respectively, by capture of the neutrons, and by deceleration of the positrons and decay of the radioactive nuclei. Results show that the calculation is consistent with the observed rise of the 2.2 MeV line on August 4, and it does not require different time dependences for the accelerated protons and electrons in the flare region. The above lags can explain the delayed gamma ray emission observed on August 7. Positrons of energies greater than about 10 MeV could be detected in interplanetary space following large solar flares.

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

    DOE R&D Accomplishments Database

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

    1951-01-31

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

  20. ETAII 6 MEV PEPPERPOT EMITTANCE MEASUREMENT

    SciTech Connect

    Paul, A C; Richardson, R; Weir, J

    2004-10-18

    We measured the beam emittance at the ETAII accelerator using a pepper-pot diagnostic at nominal parameters of 6 MeV and 2000 Amperes. During the coarse of these experiments, a ''new tune'' was introduced which significantly improved the beam quality. The source of a background pedestal was investigated and eliminated. The measured ''new tune'' emittance is {var_epsilon}= 8.05 {plus_minus} 0. 53 cm - mr or a normalized emittance of {var_epsilon}{sub n} = 943 {plus_minus} 63 mm - mr In 1990 the ETAII programmatic emphasis was on free electron lasers and the paramount parameter was whole beam brightness. The published brightness for ETAII after its first major rebuild was J = 1 - 3 x 10{sup 8} A/(m - rad){sup 2} at a current and energy of 1000-1400 Amperes and 2.5 MeV. The average normalized emittance derived from table 2 of that report is 864 mm-mr corresponding to a real emittance of 14.8 cm-mr.

  1. 7 CFR 3.20 - Standards for suspending or terminating collection activities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Standards for suspending or terminating collection activities. 3.20 Section 3.20 Agriculture Office of the Secretary of Agriculture DEBT MANAGEMENT Standards... terminating collection activities. An agency shall follow the standards set forth in 31 CFR part 903 for...

  2. 38 CFR 3.20 - Surviving spouse's benefit for month of veteran's death.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Surviving spouse's benefit for month of veteran's death. 3.20 Section 3.20 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity...

  3. 38 CFR 3.20 - Surviving spouse's benefit for month of veteran's death.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Surviving spouse's benefit for month of veteran's death. 3.20 Section 3.20 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity...

  4. 17 CFR 210.3-20 - Currency for financial statements of foreign private issuers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 2 2012-04-01 2012-04-01 false Currency for financial statements of foreign private issuers. 210.3-20 Section 210.3-20 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION FORM AND CONTENT OF AND REQUIREMENTS FOR FINANCIAL STATEMENTS, SECURITIES ACT OF 1933, SECURITIES EXCHANGE ACT OF...

  5. 17 CFR 210.3-20 - Currency for financial statements of foreign private issuers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... statements of foreign private issuers. 210.3-20 Section 210.3-20 Commodity and Securities Exchanges... private issuers. (a) A foreign private issuer, as defined in § 230.405 of this chapter, shall state... the financial statements of a foreign private issuer are stated in a currency of a country that...

  6. Gamma Cherenkov-transition radiation of high energy electrons and methods for the measurement of the refractive index of MeV photons using total internal and external reflections (Invited talk)

    NASA Astrophysics Data System (ADS)

    Ispirian, K. A.

    2014-05-01

    It is given a review of the theoretical works showing that gamma ray Cherenkov-transition radiation (GCTR) is produced in some materials the refractive index of which in gamma region is greater than 1 according to the famous results of [1]. Since there are some published doubts [2] on the theoretical results of [1], and taking into account the difficulties of the experiment [1], in order to confirm or decline the results [1] it is proposed to study experimentally GCTR and an experimental method for the measurement of refractive index of MeV photons.

  7. Elastic Neutron Scattering at 96 MeV

    SciTech Connect

    Hildebrand, A.; Blomgren, J.; Atac, A.; Bergenwall, B.; Johansson, C.; Klug, J.; Mermod, P.; Nilsson, L.; Pomp, S.; Esterlund, M.; Dangtip, S.; Tippawan, U.; Phansuke, P.; Jonsson, O.; Renberg, P.-U.; Prokofiev, A.; Nadel-Turonski, P.; Elmgren, K.; Olsson, N.; Blideanu, V.

    2005-05-24

    A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20 - 180-MeV neutron beam line of The Svedberg Laboratory, Uppsala. Elastic neutron scattering from 12C, 16O, 56Fe, 89Y, and 208Pb has been studied at 96 MeV in the 10-70 deg. interval. The results from 12C and 208Pb have recently been published,6 while the data from 16O, 56Fe, and 89Y are under analysis. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3%, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions, based on phenomenology or microscopic theory. Applications for these measurements are nuclear-waste incineration, single-event upsets in electronics, and fast-neutron therapy.

  8. Time-dependent 2.2-MeV and 0.5-MeV lines from solar flares

    NASA Technical Reports Server (NTRS)

    Wang, H. T.; Ramaty, R.

    1975-01-01

    The time dependences of the 2.2- and 0.51-MeV gamma-ray lines from solar flares are calculated, and the results are compared with observations of the 1972 August 4 and 7 flares. The time lag between the nuclear reactions and the formation of these two lines is caused by capture of the neutrons and subsequent deceleration of the positrons and decay of the radioactive nuclei. Our main results are that the calculation is consistent with the observed rise of the 2.2-MeV line on August 4, and it does not require different time dependences for the accelerated protons and high-energy electrons in the flare region. The above lags can explain the delayed gamma-ray emission observed on August 7. Positrons of energies greater than about 10 MeV could be detected in interplanetary space following large solar flares.

  9. Defect studies in one MeV electron irradiated GaAs and in Al/sub x Ga/sub l-x As P-N junction solar cells

    NASA Technical Reports Server (NTRS)

    Li, S. S.; Wang, W. L.; Loo, R. Y.; Rahilly, W. P.

    1984-01-01

    Deep level transient spectroscopy reveals that the main electron traps for one-MeV electron irradiated GaAs cells are E9c)-0.31, E(c)-0.90 eV, and the main hole trap is due to the level. Electron trap density was found to vary from 3/tens-trillion ccm for 2/one quadrillion cm 3/3.7 quadrillion cm for 21 sextillion cm electron fluence for electron fluence; a similar result was also obtained for the hole trap density. As for the grown-in defects in the Al(x)Ga(1-x)As p-n junciton cells, only two electron traps with energies of E(c)-0.20 and E(c)-0.34 eV were observed in samples with x = 0.17, and none was found for x 0.05. Auger analysis on the Al(x)Ga(1-x) As window layer of the GaAs solar cell showed a large amount of oxygen and carbon contaminants near the surface of the AlGaAs epilayer. Thermal annealing experiment performed at 250 C for up to 100 min. showed a reduction in the density of both electron traps.

  10. 5 MeV Mott Polarimeter Development at Jefferson Lab

    SciTech Connect

    Price, J. S.; Sinclair, C. K.; Cardman, L. S.; Haanskneccht, J.; Mack, D. J.; Piot, P.; Assamagan, K. A.; Grames, J.

    1997-01-01

    Low energy (E{sub k}=100 keV) Mott scattering polarimeters are ill- suited to support operations foreseen for the polarized electron injector at Jefferson Lab. One solution is to measure the polarization at 5 MeV where multiple and plural scattering are unimportant and precision beam monitoring is straightforward. The higher injector beam current offsets the lower cross-sections. Recent improvements in the CEBAF injector polarimeter scattering chamber have improved signal to noise.

  11. a Search for Peak Structures in the Positron-Electron Sum-Energy Spectra for the URANIUM-238 + TANTALUM-181 System at 6.3, 6.1, and 5.95 Mev/u.

    NASA Astrophysics Data System (ADS)

    Perera, P. A. Aloy

    1995-01-01

    The discovery of unexpected sharp peak structures in the positron energy spectra, and also in the positron -electron sum energy spectra, in the heavy-ion collision experiments carried out at GSI, Germany has initiated a great amount of experimental and theoretical interest. There is no fully consistent explanation for the origin of these peaks. APEX--the ATLAS Positron experiment--has been designed to gain insight into this puzzling positron-line phenomenon. With the data from the APEX spectrometer a search for peak structures in the positron-electron sum energy spectra was carried out for the ^{238}U+ ^{181}Ta system at 6.3, 6.1 and 5.95 MeV/u. The possibility of revealing the previously reported peak structures in positron-electron sum-energy spectra by applying cuts on the distance of closest approach, the difference-energy between positron and electron, the positron-electron opening angle, and the positron emission angle relative to the beam direction was investigated. No statistically significant peaks were observed in the APEX data.

  12. RELATIVISTIC (E > 0.6, > 2.0, AND > 4.0 MeV) ELECTRON ACCELERATION AT GEOSYNCHRONOUS ORBIT DURING HIGH-INTENSITY, LONG-DURATION, CONTINUOUS AE ACTIVITY (HILDCAA) EVENTS

    SciTech Connect

    Hajra, Rajkumar; Echer, Ezequiel; Gonzalez, Walter D.; Tsurutani, Bruce T.; Santolik, Ondrej

    2015-01-20

    Radiation-belt relativistic (E > 0.6, > 2.0, and > 4.0 MeV) electron acceleration is studied for solar cycle 23 (1995-2008). High-intensity, long-duration, continuous AE activity (HILDCAA) events are considered as the basis of the analyses. All of the 35 HILDCAA events under study were found to be characterized by flux enhancements of magnetospheric relativistic electrons of all three energies compared to the pre-event flux levels. For the E > 2.0 MeV electron fluxes, enhancement of >50% occurred during 100% of HILDCAAs. Cluster-4 passes were examined for electromagnetic chorus waves in the 5 < L < 10 and 0 < MLT < 12 region when wave data were available. Fully 100% of these HILDCAA cases were associated with enhanced whistler-mode chorus waves. The enhancements of E > 0.6, > 2.0, and > 4.0 MeV electrons occurred ∼1.0 day, ∼1.5 days, and ∼2.5 days after the statistical HILDCAA onset, respectively. The statistical acceleration rates for the three energy ranges were ∼1.8 × 10{sup 5}, 2.2 × 10{sup 3}, and 1.0 × 10{sup 1} cm{sup –2} s{sup –1} sr{sup –1} d{sup –1}, respectively. The relativistic electron-decay timescales were determined to be ∼7.7, 5.5, and 4.0 days for the three energy ranges, respectively. The HILDCAAs were divided into short-duration (D ≤ 3 days) and long-duration (D > 3 days) events to study the dependence of relativistic electron variation on HILDCAA duration. For long-duration events, the flux enhancements during HILDCAAs with respect to pre-event fluxes were ∼290%, 520%, and 82% for E > 0.6, > 2.0, and > 4.0 MeV electrons, respectively. The enhancements were ∼250%, 400%, and 27% respectively, for short-duration events. The results are discussed with respect to the current understanding of radiation-belt dynamics.

  13. XRD study of yttria stabilized zirconia irradiated with 7.3 MeV Fe, 10 MeV I, 16 MeV Au, 200 MeV Xe and 2.2 GeV Au ions

    NASA Astrophysics Data System (ADS)

    Nakano, K.; Yoshizaki, H.; Saitoh, Y.; Ishikawa, N.; Iwase, A.

    2016-03-01

    To simulate energetic neutron irradiation effects, yttria-stabilized zirconia (YSZ) which is one of the major materials for electrical corrosion potential sensors (ECP sensors) was irradiated with heavy ions at energies ranging from 7.3 MeV to 2.2 GeV. Ion irradiation effects on the lattice structure were analyzed using the X-ray diffraction (XRD). The increase in lattice constant was induced by the ion irradiation. It was dominated by the elastic collision process and not by the electronic excitation process. The lattice disordering which was observed as a broadening of XRD peaks was also induced by the irradiation especially for 200 MeV Xe ion irradiation. The present result suggests that the expansion and/or the disordering of YSZ lattice induced by energetic neutrons may affect the durability of a joint interface between a metal housing and YSZ membrane for the usage of ECP sensors in nuclear power reactors.

  14. The 50 MeV Beam Test Facility at LBL

    SciTech Connect

    Leemans, W.; Behrsing, G.; Kim, K.J.; Krupnick, J.; Matuk, C.; Selph, F.; Chattopadhyay, S.

    1993-05-01

    A new beam line, expected to be built by September 1993, will transport the 50 MeV electron beam from the ALS LINAC into an experimental area to support various R&D activities in the Center for Beam Physics at LBL. A variety of experiments are planned involving the interaction of such a relativistic electron beam with plasmas (plasma focusing), laser beams (generation of femtosecond X-ray pulses) and electromagnetic cavities (Crab cavities etc....). The beam line is designed using the measured emittance and Twiss parameters of the ALS linac. It accommodates the different requirements of the various experiments on the electron beam properties (charge, energy, pulse length) and on the handling of the beam before and after the interaction point. Special attention has also been given to incorporate diagnostics for measuring the beam properties (such as the electron energy, bunch length and charge) needed in the interpretation of the experiments.

  15. Synthesis of new 3,20-bispolyaminosteroid squalamine analogues and evaluation of their antimicrobial activities.

    PubMed

    Djouhri-Bouktab, Lamia; Vidal, Nicolas; Rolain, Jean Marc; Brunel, Jean Michel

    2011-10-27

    3,20-Amino- and polyaminosteroid analogues of squalamine and trodusquemine were synthesized involving a stereoselective titanium reductive amination reaction in high chemical yields in numerous cases. These derivatives were evaluated for their in vitro antimicrobial properties against references and clinical bacterial strains exhibiting minimum inhibitory concentrations of 2.5-40 μg/mL. The mechanism of action of these derivatives was determined using bioluminescence for ATP efflux measurements and fluorescence methods for membrane depolarization assays. PMID:21905738

  16. Evidence for the non-statistical population of the 1s2s2p4P metastable state by electron capture in 4 MeV collisions of B3+(1s2s 3S) with H2 targets

    NASA Astrophysics Data System (ADS)

    Benis, E. P.; Doukas, S.; Zouros, T. J. M.

    2016-02-01

    We have revisited previously published data involving collisions of mixed 4 MeV B3+ (1s21 S, 1 s 2 s3 S) with H2 targets (Benis et al., 2002) in search of evidence for the non-statistical production of the 1 s 2 s 2 p4 P long-lived metastable state by single electron capture. Using our recently published method for the accurate determination of the effective solid angle of Auger decaying metastable projectile states in combination with knowledge of the 1 s 2 s3 S metastable beam fraction allowed us to determine the ratio R =4 P /2 P of 1 s 2 s 2 p quartet to doublet production cross sections both formed by electron capture. Our present determination of R = 2.8 ± 0.5 , clearly departs from the expected value of R = 2 based on statistical spin recoupling arguments and thus provides evidence for the active presence of additional population mechanisms in a new collision system.

  17. Detectors for energies less than 10 MeV

    NASA Technical Reports Server (NTRS)

    1981-01-01

    In the energy domain 100 keV to 10 MeV, both crystal scintillations and semiconductors are widely used for gamma ray detectors in spectrometer systems. These detectors' operation depend on the fact that gamma rays lose energy by ionization in these materials and electrons and holes are produced. In the case of semiconductors, these electrons and holes are collected by an electric field, and they provide an electric signal that is a direct measure of the energy lost by the gamma ray in the material. Scintillation detectors depend on a further conversion of the energy lost in electron hole pair production to the production of photons. A photomultiplier tube measures the intensity of the photon flux, and an electrical pulse proportional to the photon intensity is produced at the photomultiplier output.

  18. Design of a compact spectrometer for high-flux MeV gamma-ray beams

    SciTech Connect

    Corvan, D. J. Sarri, G.; Zepf, M.

    2014-06-15

    A novel design for a compact gamma-ray spectrometer is presented. The proposed system allows for spectroscopy of high-flux multi-MeV gamma-ray beams with MeV energy resolution in a compact design. In its basic configuration, the spectrometer exploits conversion of gamma-rays into electrons via Compton scattering in a low-Z material. The scattered electron population is then spectrally resolved using a magnetic spectrometer. The detector is shown to be effective for gamma-ray energies between 3 and 20 MeV. The main properties of the spectrometer are confirmed by Monte Carlo simulations.

  19. Development of a Source of Quasi-Monochromatic MeV Energy Photons

    SciTech Connect

    Umstadter, Donald; Banerjee, Sudeep; Ramanathan, Vidya; Powers, Nathan; Cunningham, Nathaniel; Chandler-Smith, Nate

    2009-03-10

    We report current progress on a project to develop an all-optically-driven x-ray photon source. A laser pulse with 40-50 TW of peak power is focused on a supersonic helium nozzle to drive a relativistic plasma wave. Electron beams with energies of 320 MeV (+/-28 MeV) are accelerated by means of laser wakefield acceleration. Remarkably, the acceleration region is only 3 mm in length. This accelerator is currently being employed to demonstrate the generation of MeV-energy x-ray by means of all-optical Thomson scattering. By this mechanism, a lower power, laser pulse (from the same laser system) is focused onto the above laser-driven electron beam, 1-eV energy photons are Doppler-shifted in energy to >1 MeV.

  20. New Optical Constants of Amorphous and Crystalline H2O-ice, 3-20_m

    NASA Technical Reports Server (NTRS)

    Mastrapa, Rachel Michelle Elizab

    2008-01-01

    We will present new optical constants forth amorphous and crystalline H2O-ice in the spectral range 3-20 _m. Our new measurements provide high temperature resolution for crystalline H2O-ice, 10 K intervals from 20-150 K, including temperatures relevant to Solar System ices. We have found that the shape of the 3 _m feature in amorphous H2O-ice is strongly dependant on deposition temperature and the high and low density phases of amorphous H2O-ice are not easily distinguishable. We will present methods of measuring the change in band shape with phase and temperature. We acknowledge financial support from the NASA Origins of the Solar System Program and the NASA Planetary Geology and Geophysics Program.

  1. Phonon modes in cuprates possibly related to the 10 meV ARPES kink

    NASA Astrophysics Data System (ADS)

    Merritt, Adrian; Park, Seung-Ryong; Castellan, John-Paul; Gu, Genda; Reznik, Dmitry

    One of the possible mechanisms of high Tc superconductivity is Cooper pairing with the help of bosons responsible for kinks in electronic dispersion observed by angle-resolved photoemission (ARPES). Up to now most effort has been devoted to the kinks near 70 meV. More recent ARPES experiments revealed an additional energy scale near 10 meV. Since no magnetic excitations peaked at these energies have been identified, the likeliest candidates appear to be phonons. We recently performed measurements of low-energy phonons in a large single crystal sample of optimally-doped 2212 BSCCO. We measured all phonons below 15 meV. There are many branches, in particular an optic branch disperses from 7 meV from the zone center with an anticrossing with an acoustic branch near h =0.2. In addition, there is evidence for a very low energy branch dispersing through 3-4 meV. I will present these results as well as similar data on LSCO and YBCO. A comparison with recent ultrafast optics experiment detecting lattice modes around 10 meV will also be made. This work was supported by the DOE Basic Energy Sciences Neutron Scattering Program.

  2. Infrared spectroscopy of undoped and Cu-doped (80-x)Sb2O3-20Li2O-xMoO3 glasses

    NASA Astrophysics Data System (ADS)

    Petkova, P.; Boubaker, K.; Vasilev, P.; Mustafa, M.; Yumak, A.; Touihri, H.; Soltani, M. T.

    2016-04-01

    In this work, the absorption spectra of the undoped and doped with 0.1% and 0.2% CuO2 glasses with the composition (80-x)Sb2O3-20Li2O-xMoO3 are measured in the spectral region 1300-1800 nm. The optical structure of Cu2+ is investigated and the energies of the electron transitions in this metal cation are determined. The spin-orbit interaction, Lattice Compatibility Theory (LCT) analyses and the influence of molybdenum are also discussed.

  3. X-ray FEL with a meV bandwidth

    NASA Astrophysics Data System (ADS)

    Saldin, E. L.; Schneidmiller, E. A.; Shvyd'ko, Yu. V.; Yurkov, M. V.

    2001-12-01

    A new design for a single pass X-ray Self-Amplified Spontaneous Emission (SASE) FEL was proposed by Feldhaus et al. (Opt. Commun. 140 (1997) 341) and named "two-stage SASE FEL". The scheme consists of two undulators and an X-ray monochromator located between them. For the Angström wavelength range the monochromator can be realized using Bragg reflections from crystals. We propose a scheme of monochromator with a bandwidth of 20 meV for the 14.4 keV X-ray SASE FEL being developed in the framework of the TESLA linear collider project. The spectral bandwidth of the radiation from the two-stage SASE FEL (20 meV) is determined by the finite duration of the electron pulse. The shot-to-shot fluctuations of energy spectral density are dramatically reduced in comparison with the 100% fluctuations in a SASE FEL. The peak and average brilliance are three orders of magnitude higher than the values which could be reached by a conventional X-ray SASE FEL.

  4. Electron-Induced Displacement Damage Effects in CCDs

    NASA Technical Reports Server (NTRS)

    Becker, Heidi N.; Elliott, Tom; Alexander, James W.

    2006-01-01

    We compare differences in parametric degradation for CCDs irradiated to the same displacement damage dose with 10-MeV and 50-MeV electrons. Charge transfer efficiency degradation was observed to not scale with NIEL for small signals.

  5. Electron interaction in matter

    NASA Technical Reports Server (NTRS)

    Dance, W. E.; Rainwater, W. J.; Rester, D. H.

    1969-01-01

    Data on the scattering of 1-MeV electrons in aluminum for the case of non-normal incidence, electron-bremsstrahlung cross-sections in thin targets, and the production of bremstrahlung by electron interaction in thick targets, are presented both in tabular and graphic form. These results may interest physicists and radiologists.

  6. Effects of 3 MeV proton irradiation on the mechanical properties of polyimide films

    NASA Astrophysics Data System (ADS)

    Hill, David J. T.; Hopewell, Jefferson L.

    1996-11-01

    The effects of 3 MeV proton irradiation on the elongation to break, fracture energy and Young's Modulus have been investigated for films of Kapton and Ultem over the dose range 0-75 MGy at ambient temperature. The results have been compared with those reported by other workers for irradiation by 60Co gamma rays and 2 MeV electron beams under similar conditions, and little difference was found between the damage to the mechanical properties of the films induced by these three beam types.

  7. MeV negative ion generation from ultra-intense laser interaction with a water spray

    SciTech Connect

    Ter-Avetisyan, S.; Ramakrishna, B.; Borghesi, M.; Doria, D.; Zepf, M.; Sarri, G.; Ehrentraut, L.; Steinke, S.; Sandner, W.; Schnuerer, M.; Andreev, A.; Nickles, P. V.; Tikhonchuk, V.

    2011-08-01

    MeV negative oxygen ions are obtained from a water spray target irradiated by high intensity (5 x 10{sup 19} W/cm{sup 2}) and ultrashort (50 fs) laser pulses. Generation of negative ions is ascribed to electron-capture processes that the laser-accelerated high-energy positive ion experiences when it interacts with atoms in the spray. This mechanism implies the existence of a large number of MeV neutral oxygen atoms, which is consistent with indirect experimental evidence.

  8. New techniques in neutron data measurements above 30 MeV

    SciTech Connect

    Lisowski, P.W.; Haight, R.C.

    1991-01-01

    Recent developments in experimental facilities have enabled new techniques for measurements of neutron interactions above 30 MeV. Foremost is the development of both monoenergetic and continuous neutron sources using accelerators in the medium energy region between 100 and 800 MeV. Measurements of the reaction products have been advanced by the continuous improvement in detector systems, electronics and computers. Corresponding developments in particle transport codes and in the theory of nuclear reactions at these energies have allowed more precise design of neutron sources, experimental shielding and detector response. As a result of these improvements, many new measurements are possible and the data base in this energy range is expanding quickly.

  9. Measurement of 181 MeV H- ions stripping cross-sections by carbon stripper foil

    NASA Astrophysics Data System (ADS)

    Saha, P. K.; Yoshimoto, M.; Yamazaki, Y.; Hotchi, H.; Harada, H.; Okabe, K.; Kinsho, M.; Irie, Y.

    2015-03-01

    The stripping cross-sections of 181 MeV H- (negative hydrogen) ions by the carbon stripper foil are measured with good accuracy. The present experiment was carried out at the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex). The stripping cross-sections for different charge states, also known as electron loss cross-sections of H- ion, are denoted as σ-11, σ-10 and σ01, for both electrons stripping (H- →H+), one-electron stripping (H- →H0) and the 2nd-electron stripping (H0 →H+) proceeding σ-10, respectively. We have established very unique and precise techniques for such measurements so as also to determine a foil stripping efficiency very accurately. The cross-sections σ-11, σ-10 and σ01 are obtained to be (0.002 ± 0.001) ×10-18cm2, (1.580 ± 0.034) ×10-18cm2 and (0.648 ± 0.014) ×10-18cm2, respectively. The presently given cross-sections are newly available experimental results for an incident H- energy below 200 MeV and they are also shown to be consistent with recently proposed energy (1 /β2) scaled cross-sections calculated from the previously measured data at 200 and 800 MeV. The present results have a great importance not only at J-PARC for the upgraded H- beam energy of 400 MeV but also for many new and upgrading similar accelerators, where H- beam energies in most cases are considered to be lower than 200 MeV.

  10. Measured neutron carbon kerma factors from 14. 1 MeV to 18 MeV

    SciTech Connect

    Deluca, P.M. Jr.; Barschall, H.H.; Haight, R.C.; McDonald, J.C.

    1984-01-01

    For A-150 tissue-equivalent plastic, the total neutron kerma is dominated by the hydrogen kerma. Tissue kerma is inferred with reasonable accuracy by normalization to the kerma factor ratio between tissue and A-150 plastic. Because of the close match in the hydrogen abundance in these materials, the principal uncertainty is due to the kerma factors of carbon and oxygen. We have measured carbon kerma factor values of 0.183 +- 0.015 10/sup -8/ cGy cm/sup 2/ and 0.210 +- 0.16 10/sup -8/ cGy cm/sup 2/ at 14.1-MeV and 15-MeV neutron energy, respectively. A preliminary value of 0.297 +- 0.03 10/sup -8/ cGy cm/sup 2/ has been determined at 17.9 MeV. A recent microscopic cross section measurement of the (n,n'3..cap alpha..) reaction in carbon at 14.1-MeV energy gives a kerma factor of 0.184 +- 0.019 10/sup 8/ cGy cm/sup 2/ in agreement with the present result. 9 refs., 4 figs., 2 tabs.

  11. A measurement of cosmic-ray beryllium isotopes from 200 to 1500 MeV per nucleon

    NASA Technical Reports Server (NTRS)

    Buffington, A.; Orth, C. D.; Mast, T. S.

    1978-01-01

    A balloon-borne superconducting magnetic spectrometer was used in the measurement of cosmic-ray isotopic abundances from lithium through oxygen in the energy range 200-1500 MeV per nucleon. Except for Be-7 all isotopic composition is essentially energy-independent. Be-10 is nearly absent, indicating a mean cosmic-ray age of 6(-3, +10) x 10 to the 6th years. Above about 500 MeV per nucleon, Be-7 drops dramatically in abundance relative to Be-9 and C. By 1500 MeV per nucleon, the relative abundance of Be-7 has become one-half of its lower-energy value. Since Be-7 is the only isotope measured which decays by electron capture, this result is interpreted as indicating that higher-energy Be-7 had an appreciable probability of not being stripped of all its electrons before entering interstellar space where electron pickup is negligible.

  12. Measurements of galactic plane gamma ray emission in the energy range from 10 - 80 MeV

    NASA Technical Reports Server (NTRS)

    Bertsch, D. L.; Kniffen, D. A.

    1982-01-01

    A spark chamber gamma ray telescope was developed and flown to observe diffuse gamma ray emission from the central region of the galaxy. The extension of observations down to 10 MeV provides important new data indicating that the galactic diffuse gamma ray spectrum continues as a power law down to about 10 MeV, an observation in good agreement with recent theoretical predictions. Data from other experiments in the range from 100 keV to 10 MeV show a significant departure from the extension of the power-law fit to the medium energy observations reported here, possibly indicating that a different mechanism may be responsible for the emissions below and above a few MeV. The intensity of the spectrum above 10 MeV implies a galactic electron spectrum which is also very intense down to about 10 MeV. Electrons in this energy range cannot be observed in the solar cavity because of solar modulation effects. The galactic gamma ray data are compared with recent theoretical predictions.

  13. Shielding measurements for 230-Mev protons

    SciTech Connect

    Siebers, J.V.; DeLuca, P.M. Jr.; Pearson, D.W. . Dept. of Medical Physics); Coutrakon, G. . Medical Center)

    1993-09-01

    Energetic neutrons, produced as protons interact with matter, dominate the radiation shielding environment for proton accelerators. Because of the scarcity of data describing the shielding required to protect personnel from these neutrons, absorbed dose and dose-equivalent values are measured as a function of depth in a thick concrete shield at neutron emission angles of 0, 22, 45, and 90 deg for 230-MeV protons incident upon stopping-length aluminum, iron, and lead targets. Neutron attenuation lengths vary sharply with angle but are independent of the target material. Comparing results with prior shielding calculations, the High-Energy Transport Code overestimates neutron production and attenuation lengths in the forward direction. Analytical methods compare favorably in the forward direction but overestimate the production and attenuation lengths at large angles. The results presented are useful for determining the shielding requirements for proton radiotherapy facilities and as a benchmark for future calculations.

  14. Photonuclear reaction based high-energy x-ray spectrometer to cover from 2 MeV to 20 MeV

    SciTech Connect

    Sakata, S. Arikawa, Y.; Kojima, S.; Ikenouchi, T.; Nagai, T.; Abe, Y.; Inoue, H.; Morace, A.; Utsugi, M.; Nishimura, H.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Kato, R.

    2014-11-15

    A photonuclear-reaction-based hard x-ray spectrometer is developed to measure the number and energy spectrum of fast electrons generated by interactions between plasma and intense laser light. In this spectrometer, x-rays are converted to neutrons through photonuclear reactions, and the neutrons are counted with a bubble detector that is insensitive to x-rays. The spectrometer consists of a bundle of hard x-ray detectors that respond to different photon-energy ranges. Proof-of-principle experiment was performed on a linear accelerator facility. A quasi-monoenergetic electron bunch (N{sub e} = 1.0 × 10{sup −6} C, E{sub e} = 16 ± 0.32 MeV) was injected into a 5-mm-thick lead plate. Bremsstrahlung x-rays, which emanate from the lead plate, were measured with the spectrometer. The measured spectral shape and intensity agree fairly well with those computed with a Monte Carlo simulation code. The result shows that high-energy x-rays can be measured absolutely with a photon-counting accuracy of 50%–70% in the energy range from 2 MeV to 20 MeV with a spectral resolution (Δhν/hν) of about 15%. Quantum efficiency of this spectrometer was designed to be 10{sup −7}, 10{sup −4}, 10{sup −5}, respectively, for 2–10, 11–15, and 15–25 MeV of photon energy ranges.

  15. MeV ion beam interaction with polymer films containing cross-linking agents

    SciTech Connect

    Evelyn, A. L.

    1999-06-10

    Polymer films containing cross linking enhancers were irradiated with MeV alpha particles to determine the effects of MeV ion beam interaction on these materials. The contributed effects from the electronic and nuclear stopping powers were separated by irradiating stacked thin films of polyvinyl chloride (PVC), polystyrene (PS) and polyethersulfone (PES). This layered system allowed most of the effects of the electronic energy deposited to be experienced by the first layers and the last layers to receive most of the effects of the nuclear stopping power. RGA, Raman microprobe analysis, RBS and FTIR measured changes in the chemical structures of the irradiated films. The characterization resolved the effects of the stopping powers on the PVC, PS and PES and the results were compared with those from previously studied polymers that did not contain any cross linking agents.

  16. Cross Sections and Analyzing Powers of Nitrogen -15(PROTON, NEUTRON)OXYGEN-15 at 200 Mev and 494 Mev.

    NASA Astrophysics Data System (ADS)

    Ciskowski, Douglas Edward

    Differential cross sections and analyzing powers have been measured for the ^{15} N(p,n)^{15}O(g.s.) reaction at bombarding energies of 200 MeV and 494 MeV. The 494 MeV data were obtained at the LAMPF Neutron Time-Of -Flight Facility on an 82 m flight path with a resolution of about 2.7 MeV. The 200 MeV data were obtained at IUCF on a 76 m flight path with a resolution of about 1.1 MeV. At both energies, the measured analyzing power is small, the magnitude is less than.2 for momentum transfers of less than 1 fm^{-1}. In contrast, both Relativistic and standard DWIA calculations predict a maximum of A = -.7 near q = 0.7 fm ^{-1}.

  17. DPA damage analysis for 14-MeV neutrons on PFC materials

    NASA Astrophysics Data System (ADS)

    Kim, Dong-woo; Lee, Bo-young; Ko, Seung-kook; Kim, Hee-soo; Noh, Seung-jung

    2015-06-01

    The dpa (displacement per atom) damage for 14-MeV neutron in a pfc materials was simulated using MCNPX/SPECTER code. The dpa values in the main components of the structural material SS316L, Fe, Cr and Ni, were calculated to analyze the effect of nuclear damage. According to the neutron wall load for ITER design base, a neutron flux of 3.5 × 1013 neutrons/cm2·sec was applied. The simulated dpa values were found to be as 3.0 dpa/fpy for Fe, 2.9 dpa/fpy for Cr and 3.1 dpa/fpy for Ni. For practical experiments, the simulated dpa values due to the irradiation damage of 17-MeV protons were found to be as 0.67 dpa at the peak and 0.05 at the surface for SS316L using by SRIM code at the same fluence. For the 17-MeV proton irradiation, the Bragg peak appears at a 0.64-mm depth. Also, SS316L specimens irradiated by a 17-MeV proton beam with a fluence of 1016 protons/cm2 were analyzed by using transmission electron microscopy.

  18. Flare vs. Shock Acceleration of >100 MeV Protons in Large Solar Particle Events

    NASA Astrophysics Data System (ADS)

    Cliver, Edward W.

    2016-05-01

    Recently several studies have presented correlative evidence for a significant-to-dominant role for a flare-resident process in the acceleration of high-energy protons in large solar particle events. In one of these investigations, a high correlation between >100 MeV proton fluence and 35 GHz radio fluence is obtained by omitting large proton events associated with relatively weak flares; these outlying events are attributed to proton acceleration by shock waves driven by coronal mass ejections (CMEs). We argue that the strong CMEs and associated shocks observed for proton events on the main sequence of the scatter plot are equally likely to accelerate high-energy protons. In addition, we examine ratios of 0.5 MeV electron to >100 MeV proton intensities in large SEP events, associated with both well-connected and poorly-connected solar eruptions, to show that scaled-up versions of the small flares associated with classical impulsive SEP events are not significant accelerators of >100 MeV protons.

  19. ORELA measurements to meet fusion energy neutron cross section needs. [2 to 80 MeV

    SciTech Connect

    Larson, D C

    1980-01-01

    Major neutron cross section measurements made at the Oak Ridge Electron Linear Accelerator (ORELA) that are useful to the fusion energy program are reviewed. Cross sections for production of gamma rays with energies 0.3 < E/sub ..gamma../ < 10.5 MeV were measured as a function of neutron energy over the range 0.1 < E/sub n/ < 20.0 MeV for Li, C, N, O, F, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Nb, Mo, Ag, Sn, Ta, W, Au, Pb, and Th. Neutron emission cross sections have been measured for /sup 7/Li, Al, Ti, Cu, and Nb for 1 < E/sub n/ < 20 MeV. Some results of recent neutron total cross section measurements from 2 to 80 MeV for eleven materials (C, O, Al, Si, Ca, Cr, Fe, Ni, Cu, Au, and Pb) of interest to the FMIT project are presented. Finally, future directions of the ORELA program are outlined. 4 figures, 3 tables.

  20. Development of an encapsulated scintillating fiber detector as a 14-MeV neutron sensor

    NASA Astrophysics Data System (ADS)

    Singkarat, S.; Boonyawan, D.; Hoyes, G. G.; Tippawan, U.; Vilaithong, T.; Garis, N. S.; Kobus, H.

    1997-02-01

    A scintillating fiber detector has been developed and tested for use as a 14-MeV neutron sensor. The detector, designated an "Encapsulated Scintillating Fiber Detector (EFD)", is composed of a parallel array of 0.5 × 0.5 × 15 mm BCF-12 plastic scintillating fibers encapsulated in clear BC-600 optical cement. The 85 fibers from a 12 × 12 mm square array, with a separation gap of 0.8-1 mm, in the center of the 40 mm diameter × 15 mm thick hardened optical cement. It can be directly coupled to an ordinary 2 in. diameter photomultiplier tube and its simple electronics. The response of the detector to gamma-rays from isotopic sources, as well as to 2.6- and 14-MeV monoenergetic neutrons from a neutron generator has been evaluated. The detector shows 3 distinct properties simultaneously, i.e. (1) good gamma-ray pulse height reduction, (2) discrimination against 14-MeV neutrons entering at angles non-parallel to the fiber axis, and (3) production of a full energy peak of 14-MeV recoil protons in the direction of the fiber axes. Investigations by Monte Carlo simulation are also included.

  1. Valine radiolysis by MeV ions

    NASA Astrophysics Data System (ADS)

    Da Silveira, Enio

    2016-07-01

    Valine, (CH3)2 CHCH (NH2) COOH, is a protein amino acid that has been identified in extraterrestrial environments and in the Murchison meteorite [1]. The knowledge of half-lives of small organic molecules under ionizing radiation is important for the setup of models describing the spread out of prebiotics across the Solar System or the Galaxy. We have investigated typical effects of MeV cosmic ray ions on prebiotic molecules in laboratory by impinging ions produced by the PUC-Rio Van de Graaff accelerator. Pure valine films, deposited by evaporation on KBr substrates, were irradiated by H ^{+}, He ^{+} and N ^{+} ion beams, from 0.5 to 1.5 MeV and up to a fluence of 10 ^{15} projectiles/cm ^{2}. The sample temperature was varied from 10 K to 300 K. The irradiation was interrupted several times for Mid-FTIR analysis of the sample. The main findings are: 1- The column density of the valine decreases exponentially with fluence. 2- In some cases, a second exponential appears in the beginning of irradiation; this feature has been attributed to sample compaction by the ion beam [2]. 3- Destruction cross sections of valine are in the 10 ^{-15} cm ^{2} range, while compaction cross sections are in the 10 ^{-14} cm ^{2} range. 4- Destruction cross section increases with the stopping power of the beam and also with the sample temperature. 5- Surprisingly, during the radiolysis of valine, just CO _{2} is seen by as a daughter molecule formed in the bulk. 6- After long beam fluence, also a CO peak appears in the infrared spectrum; this species is however interpreted as a fragment of the formed CO2 molecules. 7- Considering the flux ratio between laboratory experiments and actual galactic cosmic rays, half-life of valine is predicted for ISM conditions [3]. This work on pure valine is the first measurement of a series. New experiments are planned for determining cross sections of valine dissolved in H _{2}O or CO _{2}, inspired by the study performed for glycine [4]. [1] P

  2. Breakup of 87 MeV [sup 11]B

    SciTech Connect

    Wolfs, F.L.H.; White, C.A.; Bryan, D.C.; Freeman, C.G.; Herrick, D.M.; Kurz, K.L.; Mathews, D.H.; Perera, P.A.A.; Zanni, M.T. )

    1994-05-01

    A segmented focal plane detector has been used to study the breakup of 87 MeV [sup 11]B ions incident on a [sup 12]C target into [sup 4]He and [sup 7]Li fragments at relative energies between 0 and 4 MeV. The relative energy spectra are dominated by sequential breakup of the 9.28 MeV, 10.26+10.33 MeV, and 10.60 MeV excited states in [sup 11]B. The measured breakup yields decrease with increasing center-of-mass scattering angle, consistent with predictions made using single-step inelastic distorted wave Born approximation calculations. Applications of this technique to study the breakup of [sup 16]O at low relative energies will be discussed.

  3. Optimization of electron cooling in the Recycler

    SciTech Connect

    Shemyakin, A.; Burov, A.; Carlson, K.; Prost, L.R.; Sutherland, M.; Warner, A.; /Fermilab

    2009-04-01

    Antiprotons in Fermilab's Recycler ring are cooled by a 4.3 MeV, 0.1A DC electron beam (as well as by a stochastic cooling system). The paper describes electron cooling improvements recently implemented: adjustments of electron beam line quadrupoles to decrease the electron angles in the cooling section and better stabilization and control of the electron energy.

  4. The Boeing 120 MeV RF linac for FEL research

    SciTech Connect

    Adamski, J.L.; Gallagher, W.J.; Kennedy, R.C.; Robinson, B.; Shoffstall, D.R.; Tyson, E.L.; Vetter, A.M.; Yeremian, A.D.

    1985-10-01

    A new electron linac for high power, visible wavelength, free electron laser research is under construction at the Boeing Radiation Laboratory in Seattle. The linac is a five section, traveling wave, L band structure with a specialized ''comb'' pulse format of widely separated high charge micropulses. The paper describes the accelerator design and prototyping of key components of the linac. These include a double subharmonic injector and a long pulse phase and amplitude stabilized RF source which have been tested on Boeing's 20 MeV S band linac.

  5. X-ray FEL with a meV bandwidth

    NASA Astrophysics Data System (ADS)

    Saldin, E. L.; Schneidmiller, E. A.; Shvyd'ko, Yu. V.; Yurkov, M. V.

    2001-08-01

    A new design for a single pass X-ray Self-Amplified Spontaneous Emission (SASE) FEL was proposed in [1] and named two-stage SASE FEL. The scheme consists of two undulators and an X-ray monochromator located between them. For the Angström wavelength range the monochromator could be realized using Bragg reflections from crystals. Proposed scheme of monochromator is illustrated for the 14.4 keV X-ray SASE FEL being developed in the framework of the TESLA linear collider project. The spectral bandwidth of the radiation from the two-stage SASE FEL (20 meV) is defined by the finite duration of the electron pulse. The shot-to-shot fluctuations of energy spectral density are dramatically reduced in comparison with the 100% fluctuations in a SASE FEL. The peak and average brilliance are by three orders of magnitude higher than the values which could be reached by a conventional X-ray SASE FEL.

  6. Precision electron polarimetry

    SciTech Connect

    Chudakov, Eugene A.

    2013-11-01

    A new generation of precise Parity-Violating experiments will require a sub-percent accuracy of electron beam polarimetry. Compton polarimetry can provide such accuracy at high energies, but at a few hundred MeV the small analyzing power limits the sensitivity. M{\\o}ller polarimetry provides a high analyzing power independent on the beam energy, but is limited by the properties of the polarized targets commonly used. Options for precision polarimetry at ~300 MeV will be discussed, in particular a proposal to use ultra-cold atomic hydrogen traps to provide a 100\\%-polarized electron target for M{\\o}ller polarimetry.

  7. Precision electron polarimetry

    SciTech Connect

    Chudakov, E.

    2013-11-07

    A new generation of precise Parity-Violating experiments will require a sub-percent accuracy of electron beam polarimetry. Compton polarimetry can provide such accuracy at high energies, but at a few hundred MeV the small analyzing power limits the sensitivity. Mo/ller polarimetry provides a high analyzing power independent on the beam energy, but is limited by the properties of the polarized targets commonly used. Options for precision polarimetry at 300 MeV will be discussed, in particular a proposal to use ultra-cold atomic hydrogen traps to provide a 100%-polarized electron target for Mo/ller polarimetry.

  8. Level Density of COBALT-57 in the Energy Region 1 Mev to 14 Mev

    NASA Astrophysics Data System (ADS)

    Mishra, Vivek

    The level density of ^{57 }Co is studied in the energy region of 1-14 MeV using three experimental techniques. Levels are counted in the resolved region, evaporation spectra are measured in the resolved to continuum region, and the coherence width is measured in the region of level overlap. Use of Hauser-Feshbach fits to the evaporation cross sections requires level densities of the residual nucleus. A two -parameter based Fermi gas form is used for the calculation of level density as a function of the nuclear excitation energy. This procedure enables level density calculation beyond the energy region in which the two fixed parameters provide the best fits to the data. A comparison is made between the level density obtained from the above described methods and the predictions of the microscopic model in an energy range of 1-20 MeV. This model utilizes a BCS pairing Hamiltonian and specific sets of single particle states and calculates numerical values of the level density. Comparisons are also made with level density of ^{57 }Co obtained in various other studies. Both the resolved level studies and the fits to the evaporation spectra were conducted using the ^{56}Fe(d,n)^{57 }Co and ^{57}Fe(p,n) ^{57}Co reactions. Standard neutron time-of-flight techniques including pulse shape discrimination for elimination of gamma -rays were employed. An energy resolution as good as 6 keV at 1-1.5 MeV neutron energy was obtained for high resolution measurements. For Ericson fluctuation measurements, the excitation functions corresponding to the ground state and the first two excited states of the residual nucleus in the ^{56}Fe(p,n) ^{56}Co reaction were obtained for lab angles between 0^circ and 150^circ. The ^{56}Fe(d,n) ^{57}Co reaction proves to be very selective in populating resolved states and includes substantial contributions from mechanisms other than the compound nuclear. The ^{57 }Fe(p,n)^{57}Co reaction populated 14 previously unknown levels. The fits to the

  9. Acceleration of ampere class H(-) ion beam by MeV accelerator.

    PubMed

    Taniguchi, M; Inoue, T; Umeda, N; Kashiwagi, M; Watanabe, K; Tobari, H; Dairaku, M; Sakamoto, K

    2008-02-01

    The H(-) ion accelerator R&D to realize the international thermonuclear experimental reactor neutral beam is ongoing at Japan Atomic Energy Agency (JAEA). The required performance for the prototype MeV accelerator developed at JAEA is 1 MeV, 500 mA (current density of 200 A/m(2)) H(-) ion beam at the beamlet divergence angle of less than 7 mrad. Up to 2005, 836 keV, 146 A/m(2) H(-) ion beam was successfully accelerated as the highest record of the current density at MeV class energy beams. In the present work, high current negative ion beam acceleration test was performed by increasing the beam extraction apertures from 3 x 3 (9 apertures) to 3 x 5 (15 apertures). By fixing the air leak at the source chamber due to backstream ions as well as the improvement of voltage holding capability by a new fiber reinforced plastic insulator ring, the performance of the MeV accelerator was improved. So far, H(-) ion beam of 320 mA was successfully accelerated up to 796 keV with the beam divergence angle of 5.5 mrad. The accelerated drain current including the electron reaches close to the power supply limit for the MeV test facility. The heat flux by the backstream ion during the above beam acceleration was estimated to be 360 W/cm(2). The Cs leakage to the accelerator during the test campaign (Cs total input of 5.0 g) was 0.26 mg (7.0 microg/cm(2)). This is considered to be the allowable level from the viewpoint of voltage holding. PMID:18315236

  10. The energy spectrum of Jovian electrons in interplanetary space

    NASA Astrophysics Data System (ADS)

    Christon, S. P.; Cummings, A. C.; Stone, E. C.; Webber, W. R.

    1985-08-01

    The energy spectrum of electrons with energies approx 10 to approx 180 MeV measured with the electron telescope on the Voyager 1 and 2 spacecraft in interplanetary space from 1978 to 1983 is studied. The kinetic energy of electrons is determined by double dE/dx measurements from the first two detectors (D1, D2) of a stack of eight solid state detectors and by the range of particle penetration into the remaining six detectors (D3 to D8) which are interleaved with tungsten absorbers. From 1978 to 1983 (radial range approx 2 to approx 12 AU) electrons of Jovian origin were clearly observable for electrons stopping in D3(e or MeV) and in D4 (E or = 8 MeV). . For electrons stopping in D5 (E or = 12 MeV), the jovian flux dominated the galactic electron flux for a period of approximately one year near the encounter with Jupiter. Jovian electrons were also observed in D6(E or = 21 Mev) 1 MeV but not in D7(E 28 MeV). A detailed interpretation of the electron variations in all energy channels depends on an accurate subtraction of background induced by energetic protons of a few 100 MeV. This substraction is facilitated by laboratory calibration results at several energies. Further results on the differential energy spectrum of Jovian electrons and limits on the maximum detected energies will be reported.

  11. Transverse Beam Emittance Measurements of a 16 MeV Linac at the Idaho Accelerator Center

    SciTech Connect

    S. Setiniyaz, T.A. Forest, K. Chouffani, Y. Kim, A. Freyberger

    2012-07-01

    A beam emittance measurement of the 16 MeV S-band High Repetition Rate Linac (HRRL) was performed at Idaho State University's Idaho Accelerator Center (IAC). The HRRL linac structure was upgraded beyond the capabilities of a typical medical linac so it can achieve a repetition rate of 1 kHz. Measurements of the HRRL transverse beam emittance are underway that will be used to optimize the production of positrons using HRRL's intense electron beam on a tungsten converter. In this paper, we describe a beam imaging system using on an OTR screen and a digital CCD camera, a MATLAB tool to extract beamsize and emittance, detailed measurement procedures, and the measured transverse emittances for an arbitrary beam energy of 15 MeV.

  12. A laser-Compton scattering prototype experiment at 100 MeV linac of Shanghai Institute of Applied Physics

    SciTech Connect

    Luo, W.; Fan, G. T.; Fan, G. W.; Li, Y. J.; Xu, Y.; Yang, L. F.; Xu, W.; Pan, Q. Y.; Cai, X. Z.; Chen, J. G.; Chen, Y. Z.; Guo, W.; Liu, W. H.; Lin, G. Q.; Ma, Y. G.; Shen, W. Q.; Xu, B. J.; Xu, J. Q.; Zhang, H. O.; Yan, Z.; and others

    2010-01-15

    As a prototype of the Shanghai Laser Electron Gamma Source in the Shanghai Synchrotron Radiation Facility, an x-ray source based on laser-Compton scattering (LCS) has been installed at the terminal of the 100 MeV linac of the Shanghai Institute of Applied Physics. LCS x-rays are generated by interactions between Q-switched Nd:yttrium aluminum garnet laser pulses [with wavelength of 1064 nm and pulse width of 21 ns (full width at half maximum)] and electron bunches [with energy of 108 MeV and pulse width of 0.95 ns (rms)] at an angle of 42 deg. between laser and electron beam. In order to measure the energy spectrum of LCS x-rays, a Si(Li) detector along the electron beam line axis is positioned at 9.8 m away from a LCS chamber. After background subtraction, the LCS x-ray spectrum with the peak energy of 29.1{+-}4.4|{sub stat}{+-}2.1|{sub syst} keV and the peak width (rms) of 7.8{+-}2.8|{sub stat}{+-}0.4|{sub syst} keV is observed. Normally the 100 MeV linac operates with the electron macropulse charge of 1.0 nC/pulse, and the electron and laser collision repetition rate of 20 Hz. Therefore, the total LCS x-ray flux of (5.2{+-}2.0)x10{sup 2} Hz can be achieved.

  13. A laser-Compton scattering prototype experiment at 100 MeV linac of Shanghai Institute of Applied Physics.

    PubMed

    Luo, W; Xu, W; Pan, Q Y; Cai, X Z; Chen, J G; Chen, Y Z; Fan, G T; Fan, G W; Guo, W; Li, Y J; Liu, W H; Lin, G Q; Ma, Y G; Shen, W Q; Shi, X C; Xu, B J; Xu, J Q; Xu, Y; Zhang, H O; Yan, Z; Yang, L F; Zhao, M H

    2010-01-01

    As a prototype of the Shanghai Laser Electron Gamma Source in the Shanghai Synchrotron Radiation Facility, an x-ray source based on laser-Compton scattering (LCS) has been installed at the terminal of the 100 MeV linac of the Shanghai Institute of Applied Physics. LCS x-rays are generated by interactions between Q-switched Nd:yttrium aluminum garnet laser pulses [with wavelength of 1064 nm and pulse width of 21 ns (full width at half maximum)] and electron bunches [with energy of 108 MeV and pulse width of 0.95 ns (rms)] at an angle of 42 degrees between laser and electron beam. In order to measure the energy spectrum of LCS x-rays, a Si(Li) detector along the electron beam line axis is positioned at 9.8 m away from a LCS chamber. After background subtraction, the LCS x-ray spectrum with the peak energy of 29.1+/-4.4|(stat)+/-2.1|(syst) keV and the peak width (rms) of 7.8+/-2.8|(stat)+/-0.4|(syst) keV is observed. Normally the 100 MeV linac operates with the electron macropulse charge of 1.0 nC/pulse, and the electron and laser collision repetition rate of 20 Hz. Therefore, the total LCS x-ray flux of (5.2+/-2.0) x 10(2) Hz can be achieved. PMID:20113090

  14. Fabrication of Al{sub 2}O{sub 3}-20 vol.% Al nanocomposite powders using high energy milling and their sinterability

    SciTech Connect

    Zawrah, M.F.; Abdel-kader, H.; Elbaly, N.E.

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Al{sub 2}O{sub 3}/Al nanocomposite powders were prepared via high energy ball milling. After 20 h milling, the size of Al{sub 2}O{sub 3}-20 vol.% Al nanocomposite particles was in the range of 23-29 nm. A uniform distribution of nanosized Al reinforcement throughout the Al{sub 2}O{sub 3} matrix, coating the particles was successfully obtained. Black-Right-Pointing-Pointer There was no any sign of phase changes during the milling. A competition between the cold welding mechanism and the fracturing mechanism were found during milling and finally the above two mechanisms reached an equilibrium. Black-Right-Pointing-Pointer The highest value of relative density was obtained for the sintered bodies at 1500 Degree-Sign C. Black-Right-Pointing-Pointer The harness of the sintered composite was decreased while the fracture toughness was improved after addition Al into alumina. -- Abstract: In this study, alumina-based matrix nanocomposite powders reinforced with Al particles were fabricated and investigated. The sinterability of the prepared nanocomposite powder at different firing temperature was also conducted. Their mechanical properties in terms of hardness and toughness were tested. Alumina and aluminum powder mixtures were milled in a planetary ball mill for various times up to 30 h in order to produce Al{sub 2}O{sub 3}-20% Al nanocomposite. The phase composition, morphological and microstructural changes during mechanical milling of the nanocomposite particles were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM) techniques, respectively. The crystallite size and internal strain were evaluated by XRD patterns using Scherrer methods. A uniform distribution of the Al reinforcement in the Al{sub 2}O{sub 3} matrix was successfully obtained after milling the powders. The results revealed that there was no any sign of phase changes during the milling. The crystal

  15. Probing the Cosmic X-Ray and MeV Gamma-Ray Background Radiation through the Anisotropy

    SciTech Connect

    Inoue, Yoshiyuki; Murase, Kohta; Madejski, Grzegorz M.; Uchiyama, Yasunobu

    2013-09-24

    While the cosmic soft X-ray background is very likely to originate from individual Seyfert galaxies, the origin of the cosmic hard X-ray and MeV gamma-ray background is not fully understood. It is expected that Seyferts including Compton thick population may explain the cosmic hard X-ray background. At MeV energy range, Seyferts having non-thermal electrons in coronae above accretion disks or MeV blazars may explain the background radiation. We propose that future measurements of the angular power spectra of anisotropy of the cosmic X-ray and MeV gamma-ray backgrounds will be key to deciphering these backgrounds and the evolution of active galactic nuclei (AGNs). As AGNs trace the cosmic large-scale structure, spatial clustering of AGNs exists. We show that e-ROSITA will clearly detect the correlation signal of unresolved Seyferts at 0.5-2 keV and 2-10 keV bands and will be able to measure the bias parameter of AGNs at both bands. Once the future hard X-ray all sky satellites achieve the sensitivity better than 10-12 erg/cm2/s-1 at 10-30 keV or 30-50 keV - although this is beyond the sensitivities of current hard X-ray all sky monitors - angular power spectra will allow us to independently investigate the fraction of Compton-thick AGNs in all Seyferts. We also find that the expected angular power spectra of Seyferts and blazars in the MeV range are different by about an order of magnitude, where the Poisson term, so-called shot noise, is dominant. Current and future MeV instruments will clearly disentangle the origin of the MeV gamma-ray background through the angular power spectrum.

  16. Product yields of sup 235 U, sup 238 U, sup 237 Np, and sup 239 Pu by photofission reactions with 20-, 30-, and 60-MeV Bremsstrahlung

    SciTech Connect

    Kase, T.; Yamadera, A.; Nakamura, T. ); Shibata, S. ); Fujiwara, I. )

    1992-08-01

    This paper reports that as a basic study of photonuclear transmutation of actinides in high-level radioactive wastes using electron-produced bremsstrahlung, the absolute yields of cumulative mass distributions and the transmutation rate of {sup 235}U, {sup 238}U, {sup 237}Np, and {sup 239}Pu by photofission reactions induced by 20-, 30-, and 60-MeV bremsstrahlung were measured. The results of mass yield distributions and transmutation yields agree well with other experimental results and those calculated using photofission cross sections, respectively. The transmutation efficiency per electron increases about one order of magnitude with electron energy from 20 to 60 MeV.

  17. Final Report for Nuclear Resonance Fluorescence Measurements of 239Pu above 2.5 MeV

    SciTech Connect

    Johnson, M S; McNabb, D P

    2009-01-07

    Nuclear Resonance Fluorescence measurements were performed at the free electron laser facility at UC Santa Barbara using a bremsstrahlung beam. Three endpoint energies were chosen for the bremsstrahlung to cover as much area above 2.5 MeV as possible. We were able to set an upper limit of NRF state strengths between 2.5 and 3.8 MeV at roughly 38(5) eV barns at the 4-sigma level and 9(2) eV barns at the 1-sigma level. Published results on states near 2.4 MeV indicate strengths about 10(2) eV barns. Details of the results are presented in this report.

  18. Production of 14 MeV neutrons by heavy ions

    DOEpatents

    Brugger, Robert M.; Miller, Lowell G.; Young, Robert C.

    1977-01-01

    This invention relates to a neutron generator and a method for the production of 14 MeV neutrons. Heavy ions are accelerated to impinge upon a target mixture of deuterium and tritium to produce recoil atoms of deuterium and tritium. These recoil atoms have a sufficient energy such that they interact with other atoms of tritium or deuterium in the target mixture to produce approximately 14 MeV neutrons.

  19. COMPTEL neutron response at 17 MeV

    NASA Technical Reports Server (NTRS)

    Oneill, Terrence J.; Ait-Ouamer, Farid; Morris, Joann; Tumer, O. Tumay; White, R. Stephen; Zych, Allen D.

    1992-01-01

    The Compton imaging telescope (COMPTEL) instrument of the Gamma Ray Observatory was exposed to 17 MeV d,t neutrons prior to launch. These data were analyzed and compared with Monte Carlo calculations using the MCNP(LANL) code. Energy and angular resolutions are compared and absolute efficiencies are calculated at 0 and 30 degrees incident angle. The COMPTEL neutron responses at 17 MeV and higher energies are needed to understand solar flare neutron data.

  20. Diagnostics for the 400 MeV FNAL Linac

    SciTech Connect

    McCrory, E.S.; Lee, G.

    1991-02-01

    The last four 201 MHz alvarez tanks of the twenty-year-old, 200 MeV Fermilab Linac are being replaced by seven high-gradient (7 KV/m), high-frequency (805 MHz) side-coupled-cavity structures to produce a 400 MeV beam for injection into the Booster. Good, reliable beam diagnostics are an important factor in the success of this project. This paper discusses the diagnostic systems.

  1. Energy spectrum and flux of 3- to 20-Mev neutrons and 1- to 10-Mev gamma rays in the atmosphere

    NASA Technical Reports Server (NTRS)

    Klumpar, D. M.; Lockwood, J. A.; Saint Onge, R. N.; Friling, L. A.

    1973-01-01

    An experiment is described which was designed to measure the neutron and gamma ray energy spectrums and fluxes in the energy intervals 3 to 20 MeV and 1 to 10 MeV, respectively. In addition, from the 3 to 20-MeV proton recoil spectrums it is possible to infer the shape of the neutron energy spectrum from 20 to 50 MeV. The detecting system utilized a separate charged particle rejection scheme and a two-parameter display system for the output from the pulse shape discrimination which separated gamma rays from neutrons (n). Two long-duration flights were made with this detector in 1970 at Palestine, Tex. (P sub c = 4.6 Gv) and at Ft. Churchill, Canada (P sub c = 0.3 Gv).

  2. Neutron transition densities for 48Ca from proton scattering at 200 and 318 MeV

    NASA Astrophysics Data System (ADS)

    Feldman, A. E.; Kelly, J. J.; Flanders, B. S.; Khandaker, M. A.; Seifert, H.; Boberg, P.; Hyman, S. D.; Karen, P. H.; Norum, B. E.; Welch, P.; Chen, Q.; Bacher, A. D.; Berg, G. P.; Stephenson, E. J.; Nanda, S.; Saha, A.; Scott, A.

    1994-04-01

    Differential cross sections and analyzing powers for scattering of 200 and 318 MeV protons have been measured for states of 48Ca up to 7 MeV of excitation. The data cover c.m. momentum transfers from approximately 0.4 to 3.0 fm-1. Neutron transition densities were extracted for the 2+1,3-1,3-2,4+2, and 5-1 states using density-dependent empirical effective interactions previously calibrated upon elastic and inelastic scattering data for 16O and 40Ca. The corresponding proton transition densities were obtained from electron scattering data and held fixed during the analysis. Fits performed to the data for either energy provide excellent predictions for the other. Neutron densities fitted to data for either energy independently agree very well with each other and with the densities fitted to both data sets simultaneously. These densities are also consistent with earlier data for 500 MeV protons. The energy-independence of the extracted transition densities demonstrates that residual errors in the reaction model are compatible with the error bands estimated by the fitting procedure. Several additional tests of the model dependence of the results were performed also. The proton and neutron transition densities are compared with calculations based upon the extended random phase approximation, which includes 2p2h correlations. These calculations are most successful for densities dominated by 1p1h configurations, whereas densities requiring substantial 2p2h contributions tend to be underestimated.

  3. The HESR Electron Cooling Proposal

    SciTech Connect

    Reistad, D.

    2006-03-20

    The maximum electron energy of the HESR electron cooling system has been decided to be 4.5 MeV, with a possible future upgrade to 8 MeV. Calculations with BETACOOL have been carried out; these include effects of imperfections of the electron beam as well as the internal hydrogen pellet target and intra-beam scattering. Design work is going on. This makes use of the experience gained at the FNAL Recycler and aims to result in a practical solution, which includes considerations for robustness as well as ease of assembly, bake-out, and to make use of proven solutions as much as possible.

  4. Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams

    SciTech Connect

    Hastings, J.B.; Rudakov, F.M.; Dowell, D.H.; Schmerge, J.F.; Cardoza, J.D.; Castro, J.M.; Gierman, S.M.; Loos, H.; Weber, P.M.; /Brown U.

    2006-10-24

    An rf photocathode electron gun is used as an electron source for ultrafast time-resolved pump-probe electron diffraction. We observed single-shot diffraction patterns from a 160 nm Al foil using the 5.4 MeV electron beam from the Gun Test Facility at the Stanford Linear Accelerator. Excellent agreement with simulations suggests that single-shot diffraction experiments with a time resolution approaching 100 fs are possible.

  5. LOW VOLTAGE 14 Mev NEUTRON SOURCE

    DOEpatents

    Little, R.N. Jr.; Graves, E.R.

    1959-09-29

    An apparatus yielding high-energy neutrons at the rate of 10/sup 8/ or more per second by the D,T or D,D reactions is described. The deuterium gas filling is ionized by electrons emitted from a filament, and the resulting ions are focused into a beam and accelerated against a fixed target. The apparatus is built in accordance with the relationship V/sub s/ = A--B log pd, where V/sub s/ is the sparking voltage, p the gas pressure, and d the gap length between the high voltage electrodes. Typical parameters to obtain the high neutron yields are 55 to 80 kv, 0.5 to 7.0 ma beam current, 5 to 12 microns D/sub 2/, and a gap length of 1 centimeter.

  6. MeV H+ ion irradiation effect on the stoichiometry of polyethylene terephthalate films

    NASA Astrophysics Data System (ADS)

    Abdesselam, M.; Muller, D.; Djebara, M.; Ouichaoui, S.; Chami, A. C.

    2013-07-01

    Appropriate experimental conditions have been chosen to investigate the influence of main H+ ion irradiation parameters on stoichiometry changes induced in polyethylene terephthalate (PET) thin films. Stacks of six self-supporting identical films were irradiated perpendicularly to the target surface. Thus, the irradiations were realized simultaneously at different values of the target electronic stopping power, ɛ+. Indeed, the initial H+ ion energy of 1.1 MeV incident on the front polymer film was degraded down to 0.48 MeV at the entrance of the rear stacked film, which corresponds to an increase of ɛ+ from ˜0.22 up to ˜0.41 MeV cm2 mg-1. Ion fluences in the range (0.05-4) × 1015 cm-2 corresponding to an ion dose interval 1.80-263 MGy were used. The (H, O, C) atomic surface densities of the PET polymeric films were quantitatively determined by IBA techniques using a 1.62 MeV deuteron beam leading to the following main results: for each target film stacked at a given position thus fixed ɛ+, the oxygen atomic density decreases linearly versus ion fluence, ϕ; for the different ɛ+, the hydrogen impoverishment of the PET target is insignificant below critical fluence ϕc ˜ 1.5 × 1015 cm-2 and becomes substantial above ϕc; for fixed ϕ, the hydrogen and oxygen atomic densities exhibit linear decreases versus ɛ+; all measured such data versus ϕ and ɛ+ merge together into a unique decreasing curve for each (H, O, C) polymer content element when represented in function of the H+ ion dose, D, tightly correlating the latter two parameters; the O content element release from the PET target appears to be the most important, followed by the H content depletion, while the target C content is least affected under H+ ion irradiation.

  7. Impurity/defect interactions during MeV Si{sup +} ion implantation annealing

    SciTech Connect

    Agarwal, A.; Koveshnikov, S.; Christensen, K.

    1995-08-01

    Ion implantation of dopant atoms at MeV energies is currently being explored in several integrated circuit device manufacturing processes. MeV implantation offers immediate advantages such as vertical well modulation, latch-up protection, device structure isolation, and reduced temperature processing. Simultaneously, it presents an opportunity to achieve {open_quotes}proximity{close_quotes} gettering of impurities from the active device region by placing high impurity solubility and/or secondary defect gettering sites within microns of the surface. If the MeV implanted species is a dopant ion, all three gettering mechanisms, i.e, segregation, relaxation and injection, can be involved in the gettering process, complicating the analysis and optimization of the process. However, investigation of gettering using non-dopant Si{sup +} ion damage allows the relaxation component of the gettering process to be isolated and examined separately. In general, gettering is verified by a reduction in impurity concentration in the region of interest, usually the device region, and/or a build-up of concentration/precipitation in a non-device sink region. An alternate and more meaningful approach is to use simple devices as materials characterization probes via changes in the electrical activity of the gettering sites. Device space charge probes also allow the evolution of the defect sites upon contamination to be tracked. We report here results of the electrical, structural, and chemical characterization of MeV implanted Si{sup +} damage using Deep Level Transient Spectroscopy (DLTS), Transmission Electron Microscopy (TEM), and Secondary Ion Mass Spectroscopy (SIMS). The damage has been characterized both as a function of annealing from 600 to 1100{degrees}C for 1 hr, and after contamination with Fe followed by low temperature gettering annealing.

  8. FTIR analysis of polyethylene terephthalate irradiated by MeV He+

    NASA Astrophysics Data System (ADS)

    Djebara, M.; Stoquert, J. P.; Abdesselam, M.; Muller, D.; Chami, A. C.

    2012-03-01

    The degradation induced by MeV He+ ions onto polyethylene terephthalate (PET) is investigated as a function of fluence and electronic stopping power (dE/dx)e. Stack samples of four 3.6 μm PET films are irradiated by 3.5 MeV He+ under vacuum and room temperature at fluence ranging from 1013 to 1.5 × 1015 He+ cm-2. The entrance energies range from 3.5 MeV for the front film to 0.573 MeV for the rear one at the beginning of the irradiation and the corresponding mean (dE/dx)e lie for pristine PET between 158 and 264 keV/μm. A Fourier transform infrared spectroscopy (FTIR) analysis is undertaken. The different stack films present similar damages with magnitude increase as the fluence goes up. Moreover, higher is the electronic stopping power (dE/dx)e more important is the damage. The evolution of the normalized integrated absorbance A(ϕ)/A0 of the internal reference 1410 cm-1 band as a function of the fluence ϕ presents a complex behavior characterized by a two-exponential decay associated to low and high fluence range. The analysis reveals clearly that the A(ϕ)/A0 of the characteristic benzene ring 1577 cm-1 band remains steady till fluence around 3 × 1014 He+ cm-2 and then decreases smoothly as fluence increases. The band appearing at 1610 cm-1, assigned to mono substituted benzene, presents an integrated absorbance A(ϕ) which rises progressively and levels off beyond a critical fluence around 4 × 1014 He+ cm-2. The cross section of the creation of the monosubstituted benzene lies between 3 × 10-15 and 6 × 10-15 cm2 for (dE/dx)e = 158 and 264 keV/μm, respectively. Drastic loss of crystallinity is induced by the MeV He+ ion irradiation in the polymer. The amorphization is monitored by the evolution of the specific bands of the trans and gauche ethylene glycol residue conformations. A sudden drop in the integrated absorbance of the 1340 cm-1 band which characterizes the trans conformation is observed at fluence around 2 × 1014 He+ cm-2. On the other hand, a

  9. Pulse compression system for the ANL 20 MeV linac

    SciTech Connect

    Mavrogenes, G.; Norem, J.; Simpson, J.

    1986-01-01

    This paper describes the pulse compression system being built on the Argonne 20 MeV electron linac. The system is designed to rotate the bunch from the present measured pulse length of 38 psec FWHM, to pulse lengths of 5 to 6 ps with the large instantaneous currents (1 to 4 kA) possible instantaneous current. This system was necessary to extend the study of reactive fragments of molecules to the time scale of a few picoseconds, in particular to examine the chemistry of electrons and ions before and during relaxation of the surrounding media. These experiments are not sensitive to the beam energy spread, High Energy Physics experiments studying wake fields have also been proposed using the short bunches and the facility was designed so that the wake field experiment could share the beam bunching system. The 20 MeV electron linac uses a double gap, 12th subharmonic prebuncher together with a one wavelength 1.3 Ghz prebuncher to produce a single pulse of 38 ps from one occupied rf bucket. Beam emittances of 15.7 mmmr have been measured for 40 nC of accelerated charge and 8 mmmr at 10 nC. The energy spread of dE/E = 1% (FWHM) has been measured at 40 nC. Thus the accelerated beam has excellent time structure, high current, and good emittance.

  10. New source of MeV negative ion and neutral atom beams.

    PubMed

    Ter-Avetisyan, S; Braenzel, J; Schnürer, M; Prasad, R; Borghesi, M; Jequier, S; Tikhonchuk, V

    2016-02-01

    The scenario of "electron-capture and -loss" was recently proposed for the formation of negative ion and neutral atom beams with MeV kinetic energies. However, it does not explain why the formation of negative ions in a liquid spray is much more efficient than with an isolated atom. The role of atomic excited states in the charge-exchange processes is considered, and it is shown that it cannot account for the observed phenomena. The processes are more complex than the single electron-capture and -loss approach. It is suggested that the shell effects in the electronic structure of the projectile ion and/or target atoms may influence the capture/loss probabilities. PMID:26932016

  11. New source of MeV negative ion and neutral atom beams

    NASA Astrophysics Data System (ADS)

    Ter-Avetisyan, S.; Braenzel, J.; Schnürer, M.; Prasad, R.; Borghesi, M.; Jequier, S.; Tikhonchuk, V.

    2016-02-01

    The scenario of "electron-capture and -loss" was recently proposed for the formation of negative ion and neutral atom beams with MeV kinetic energies. However, it does not explain why the formation of negative ions in a liquid spray is much more efficient than with an isolated atom. The role of atomic excited states in the charge-exchange processes is considered, and it is shown that it cannot account for the observed phenomena. The processes are more complex than the single electron-capture and -loss approach. It is suggested that the shell effects in the electronic structure of the projectile ion and/or target atoms may influence the capture/loss probabilities.

  12. Formation of diamond in carbon onions under MeV ion irradiation

    NASA Astrophysics Data System (ADS)

    Wesolowski, P.; Lyutovich, Y.; Banhart, F.; Carstanjen, H. D.; Kronmüller, H.

    1997-10-01

    Spherical carbon onions are generated by irradiating graphitic carbon soot with Ne+ ions of 3 MeV energy. Under continued irradiation, a transformation of their cores to cubic diamond crystals is observed. In comparison to earlier electron irradiation experiments, the yield of diamond is much higher. The output of the irradiation experiment is characterized by electron microscopy and electron energy loss spectroscopy. Knock-on displacements of carbon atoms by Ne+ ions are assumed to be responsible for a self-compression of the onions, leading to the nucleation of diamond in their cores. The increased diamond yield is explained by the higher displacement cross-section, the higher energy transfer, and the higher total beam current on the specimen.

  13. Formation of diamond in carbon onions under MeV ion irradiation

    SciTech Connect

    Wesolowski, P.; Lyutovich, Y.; Banhart, F.; Carstanjen, H.D.; Kronmueller, H.

    1997-10-01

    Spherical carbon onions are generated by irradiating graphitic carbon soot with Ne{sup +} ions of 3 MeV energy. Under continued irradiation, a transformation of their cores to cubic diamond crystals is observed. In comparison to earlier electron irradiation experiments, the yield of diamond is much higher. The output of the irradiation experiment is characterized by electron microscopy and electron energy loss spectroscopy. Knock-on displacements of carbon atoms by Ne{sup +} ions are assumed to be responsible for a self-compression of the onions, leading to the nucleation of diamond in their cores. The increased diamond yield is explained by the higher displacement cross-section, the higher energy transfer, and the higher total beam current on the specimen. {copyright} {ital 1997 American Institute of Physics.}

  14. Applied radiation research around a 15 MeV high-average-power linac

    NASA Astrophysics Data System (ADS)

    Lahorte, P.; Mondelaers, W.; De Frenne, D.; Callens, F.; Vanhaelewyn, G.; Schacht, E.; Van Calenberg, S.; Van Cleemput, O.; Huyghebaert, A.

    1999-08-01

    The Department of Subatomic and Radiation Physics of the University Gent is equipped with a 15 MeV 20 kW linear electron accelerator (linac) facility. In its present configuration the accelerator is used as a multipurpose apparatus for research in the fields of polymer chemistry, biomedical materials, medicine, food technology, dosimetry, solid state physics, agriculture and nuclear and radiation physics. We present an overview of both the various research projects around our linac facility involving radiation chemistry and physics and the specialised technologies facilitating this research.

  15. Inverse free electron laser accelerator

    SciTech Connect

    Fisher, A.; Gallardo, J.; Sandweiss, J.; van Steenbergen, A. )

    1992-07-01

    The study of the INVERSE FREE ELECTRON LASER, as a potential mode of electron acceleration, is being pursued at Brookhaven National Laboratory. Recent studies have focussed on the development of a low energy, high gradient, multi stage linear accelerator. The elementary ingredients for the IFEL interaction are the 50 MeV Linac e[sup [minus

  16. Inverse Free Electron Laser accelerator

    SciTech Connect

    Fisher, A.; Gallardo, J.; van Steenbergen, A. ); Sandweiss, J. )

    1992-09-01

    The study of the INVERSE FREE ELECTRON LASER, as a potential mode of electron acceleration, is being pursued at Brookhaven National Laboratory. Recent studies have focussed on the development of a low energy, high gradient, multi stage linear accelerator. The elementary ingredients for the IFEL interaction are the 50 MeV Linac e[sup [minus

  17. Crab Nebula observations - 0.2-10 MeV

    NASA Technical Reports Server (NTRS)

    Gruber, D. E.

    1975-01-01

    Observations of the total emission from the Crab Nebula and also of the pulsed component were made over the 0.2 to 10-MeV range during three balloon flights in 1971 with an actively-collimated NaI scintillator. The total emission flux was positively observed over the entire interval. The observed spectrum to 1 MeV agrees with an extrapolation of the E to the -2.2 power law, which fits lower-energy data. The observations above 1 MeV are factors of 3 and 20 above this law and are better fit with a spectral index of 0.8. Confidence levels are 3 sigma or better for each half-decade band. The three observations are consistent with a constant flux level. The NP 0532 flux, detected during one flight only (August 8) between 0.2 and 0.38 MeV, agrees with the exponential power law spectrum already determined from other observations. The possibility of a rapidly rising pulsed emission fraction over the 0.1- to 1-MeV interval is excluded by this observation.

  18. Solar Gamma Rays Above 8 MeV

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Crannell, H.; Ramaty, R.

    1978-01-01

    Processes which lead to the production of gamma rays with energy greater than 8 MeV in solar flares are reviewed and evaluated. Excited states produced by inelastic scattering, charge exchange, and spallation reactions in the abundant nuclear species are considered in order to identify nuclear lines which may contribute to the Gamma ray spectrum of solar flares. The flux of 15.11 MeV Gamma rays relative to the flux of 4.44 MeV Gamma rays from the de-excitation of the corresponding states in C12 is calculated for a number of assumed distributions of exciting particles. This flux ratio is a sensitive diagnostic of accelerated particle spectra. Other high energy nuclear levels are not so isolated as the 15.11 MeV state and are not expected to be so strong. The spectrum of Gamma rays from the decay of Pi dey is sensitive to the energy distribution of particles accelerated to energies greater than 100 MeV.

  19. The background model in the energy range from 0.1 MeV up to several MeV for low altitude and high inclination satellites.

    NASA Astrophysics Data System (ADS)

    Arkhangelskaja, I. V.; Arkhangelskiy, A. I.

    2016-02-01

    The gamma-ray background physical origin for low altitude orbits defined by: diffuse cosmic gamma-emission, atmospheric gamma-rays, gamma-emission formed in interactions of charged particles (both prompt and activation) and transient events such as electrons precipitations and solar flares. The background conditions in the energy range from 0.1 MeV up to several MeV for low altitude orbits differ due to frequency of Earth Radiation Belts - ERBs (included South Atlantic Anomaly - SAA) passes and cosmic rays rigidity. The detectors and satellite constructive elements are activated by trapped in ERBs and moving along magnetic lines charged particles. In this case we propose simplified polynomial model separately for polar and equatorial orbits parts: background count rate temporal profile approximation by 4-5 order polynomials in equatorial regions, and linear approximations, parabolas or constants in polar caps. The polynomials’ coefficients supposed to be similar for identical spectral channels for each analyzed equatorial part taken into account normalization coefficients defined due to Kp-indexes study within period corresponding to calibration coefficients being approximately constants. The described model was successfully applied for the solar flares hard X-ray and gamma-ray emission characteristic studies by AVS-F apparatus data onboard CORONAS-F satellite.

  20. Electron irradiation of modern solar cells

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Miyahira, T. F.

    1977-01-01

    A number of modern solar cell types representing 1976 technology (as well as some older types) were irradiated with 1 MeV electrons (and a limited number with 2 MeV electrons and 10 MeV protons). After irradiation, the cells were annealed, with I-V curves measured under AMO at 30 C. The purpose was to provide data to be incorporated in the revision of the solar cell radiation handbook. Cell resistivities ranged from 2 to 20 ohm-cm, and cell thickness from 0.05 to 0.46 mm. Cell types examined were conventional, shallow junction, back surface field (BSF), textured, and textured with BSF.

  1. An RFQ accelerator system for MeV ion implantation

    NASA Astrophysics Data System (ADS)

    Hirakimoto, Akira; Nakanishi, Hiroaki; Fujita, Hiroyuki; Konishi, Ikuo; Nagamachi, Shinji; Nakahara, Hiroshi; Asari, Masatoshi

    1989-02-01

    A 4-vane-type Radio-Frequency Quadrupole (RFQ) accelerator system for MeV ion implantation has been constructed and ion beams of boron and nitrogen have been accelerated successfully up to an energy of 1.01 and 1.22 MeV, respectively. The acceleration of phosphorus is now ongoing. The design was performed with two computer codes called SUPERFISH and PARMTEQ. The energy of the accelerated ions was measured by Rutherford backscattering spectroscopy. The obtained values agreed well with the designed ones. Thus we have confirmed the validity of our design and have found the possibility that the present RFQ will break through the production-use difficulty of MeV ion implantation.

  2. Industrial applications using 14 MeV neutrons at KFUPM

    NASA Astrophysics Data System (ADS)

    Aksoy, A.; Khiari, F. Z.; Al-Haddad, M. N.

    1999-06-01

    The objective of this study is to develop a database for the technical capability of the KFUPM 14 MeV Neutron Activation Analysis (NAA) Facility for applications to various local industries in the Kingdom. Since the 14 MeV NAA is a well-established non-destructive, rapid and sensitive technique for elemental bulk analysis, the applications of the technique are spread over wide areas such as oil, petrochemicals, metal and mining, medicine, agriculture and environment. The applications are mostly done for determination of light elements such as oxygen, nitrogen, fluorine, silicon and phosphorus, which are relatively difficult to determine by other methods. The results of the analysis are mainly used for quality and process control. The progress made in developing the KFUPM 14 MeV NAA Facility for industrial applications will be summarized. Preliminary results of the analysis of the data collected using the facility will be presented and discussed.

  3. Gamma-ray burst variability above 4 MeV

    NASA Technical Reports Server (NTRS)

    Schwartz, R. A.; Ling, J. C.; Wheaton, W. A.; Jacobson, A. S.; Mahoney, W. A.

    1985-01-01

    The relationship between the hard X-ray and gamma ray emissions during four bursts using the anti-coincidence shields of the High Energy Astronomy Observatory 3 (HEAO 3) Gamma Ray Spectrometer is explored. Recent observations of gamma ray bursts by the Solar Maximum Mission Gamma Ray Spectrometer (GRS) have shown that high energy emission above 1 MeV is a common and energetically important feature (Matz et al. 1985). Time histories of four gamma ray bursts in 3 energy bands ( keV, around 511 keV, and 4 MeV) with 10.24 a resolution show that the 4 MeV flux is only weakly coupled to the spectrum below approximately 600 keV.

  4. Nuclear Resonance Fluorescence from Uranium above 2 MeV

    NASA Astrophysics Data System (ADS)

    Kwan, E.; Howell, C. R.; Raut, R.; Rusev, G.; Tonchev, A. P.; Tornow, W.; Adekola, A.; Hammond, S. L.; Karwowski, H. J.; Tompkins, J. R.; Huibregtse, C.; Kelley, J. H.; Johnson, B.

    2009-10-01

    The detection of special nuclear materials is critical to the nation's efforts to counter serious threat from nuclear terrorist attacks. A research program has been initiated at TUNL to address the need for new nuclear data on the actinides using the High-Intensity Gamma-Ray Source (HIγS). The high-intensity nearly monoenergic and 100% polarized γ-ray beams from HγS were utilized to search for dipole states in ^235U and ^238U above 2 MeV. This information is necessary for developing technologies using Nuclear-Resonance Fluorescence (NRF) to nonintrusively scan cargo for specific nuclei. The existence of strong nuclear dipole transitions in the actinides above 2 MeV is important for nuclear forensics, because interrogation photons using NRF are the most penetrating at these energies. Results from our experiments at Eγ> 2.0 MeV on uranium will be presented.

  5. Earth albedo neutrons from 10 to 100 MeV.

    NASA Technical Reports Server (NTRS)

    Preszler, A. M.; Simnett, G. M.; White, R. S.

    1972-01-01

    We report the measurement of the energy and angular distributions of earth albedo neutrons from 10 to 100 MeV at 40 deg N geomagnetic latitude from a balloon at 120,000 ft, below 4.65 g/sq cm. The albedo-neutron omnidirectional energy distribution is flat to 50 MeV, then decreases with energy. The absolute neutron energy distribution is of the correct strength and shape for the albedo neutrons to be the source of the protons trapped in earth's inner radiation belt.

  6. Photon detector for MEGA. [53 MeV

    SciTech Connect

    Gagliardi, C.A.; Tribble, R.E.

    1992-01-01

    The MEGA photon detector is designed to observe the 52.83-MeV photon produced in a [mu] [yields] e[gamma] decay with an energy resolution of 1.25 MeV, a position resolution of 2 [times] 5 mm[sup 2], a directional resolution of 10[degree], a time resolution of 500 ps, and an efficiency of about 5.4%. It will consist of three independent concentric cylindrical pair spectrometers mounted within a 1.5 T magnetic field produced by a superconducting solenoid magnet. Each pair spectrometer includes two thin Pb foils to convert photons into e[sup +]e[sup [minus

  7. A P + DEUTERON PROTON POLARIMETER AT 200 MEV.

    SciTech Connect

    HUANG,H.; ROSER,T.; ZELENSKI,A.; KURITA,K.; STEPHENSON,E.; TOOLE,R.

    2002-06-02

    There has been concern about the analyzing power of the p-Carbon polarimeter at the end of 200 MeV LINAC of BNL. A new polarimeter based on proton-deuteron scattering was installed and we have repeated the calibration of proton-Carbon scattering at 12 degrees and 200 MeV against proton-deuteron scattering. The result is consistent with the value of A=0.62 now used to measure the beam polarization at the end of the LINAC.

  8. Resolution considerations in MeV ion microscopy and lithography

    NASA Astrophysics Data System (ADS)

    Norarat, Rattanaporn; Whitlow, Harry J.

    2015-04-01

    There a disparity between the way the resolution is specified in microscopy and lithography using light compared to MeV ion microscopy and lithography. In this work we explore the implications of the way the resolution is defined with a view to answering the questions; how are the resolving powers in MeV ion microscopy and lithography relate to their optical counterparts? and how do different forms of point spread function affect the modulation transfer function and the sharpness of the edge profile?

  9. Large scale silver nanowires network fabricated by MeV hydrogen (H+) ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Honey, S.; Naseem, S.; Ishaq, A.; Maaza, M.; Bhatti, M. T.; Wan, D.

    2016-04-01

    A random two-dimensional large scale nano-network of silver nanowires (Ag-NWs) is fabricated by MeV hydrogen (H+) ion beam irradiation. Ag-NWs are irradiated under H+ ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H+ ion beam-induced welding of Ag-NWs at intersecting positions. H+ ion beam induced welding is confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, the structure of Ag NWs remains stable under H+ ion beam, and networks are optically transparent. Morphology also remains stable under H+ ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H+ ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps: ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices. Project supported by the National Research Foundation of South Africa (NRF), the French Centre National pour la Recherche Scientifique, iThemba-LABS, the UNESCO-UNISA Africa Chair in Nanosciences & Nanotechnology, the Third World Academy of Science (TWAS), Organization of Women in Science for the Developing World (OWSDW), the Abdus Salam ICTP via the Nanosciences African Network (NANOAFNET), and the Higher Education Commission (HEC) of Pakistan.

  10. Design study for a superconducting proton linac from 20 to 100 MeV

    SciTech Connect

    Wangler, T.P.; Garnett, R.; Krawczyk, F.; Billen, J.; Bultman, N.; Christensen, K.; Fox, W.; Wood, R.

    1993-07-01

    Advances in superconducting radiofrequency technology during the past 15 years have made possible the large-scale application of superconducting niobium accelerators. So far this development has been restricted to rather low-current electron and heavy-ion accelerators. In addition to the power savings, the improved capability of superconducting cavities to provide acceleration of high currents with low beam losses, which follows from the ability to use larger beam apertures without a large economic penalty from increased rf losses, could make superconducting proton linacs very attractive for high-intensity applications, where activation of the accelerator is a major concern. During the past year, at Los Alamos, the authors have been looking at a possible upgrade to the 800-MeV LAMPF proton accelerator, to provide higher intensity injection into a new storage ring for a new high-intensity pulsed neutron source. As part of this upgrade to the LAMPF accelerator, the entire linac below 100 MeV would be rebuilt to provide improved beam quality, improved reliability, and to include funneling at 20 MeV for higher beam currents. Both a room-temperature and a superconducting option are being considered for the section from 20 to 100 MeV. At present, this section is a 201.25 MHz room-temperature copper drift-tube linac (DTL). For this new upgrade scenario the frequency from 20 to 100 MeV was fixed at 805 MHz. The new duty factor is assumed to be 7.2%, and the authors show some results at two currents, 30 mA and 150 mA, that span the range of interest. Their superconducting linac concept consists of individual multicell cavities, each driven by a klystrode. Focusing would be provided by superconducting quadrupole lenses between cavities. In the remainder of the paper they describe their study to evaluate the potential of a superconducting proton linac section for this application, and address some of the many design choices.

  11. Electron beam accelerator with magnetic pulse compression and accelerator switching

    DOEpatents

    Birx, D.L.; Reginato, L.L.

    1984-03-22

    An electron beam accelerator is described comprising an electron beam generator-injector to produce a focused beam of greater than or equal to .1 MeV energy electrons; a plurality of substantially identical, aligned accelerator modules to sequentially receive and increase the kinetic energies of the beam electron by about .1-1 MeV per module. Each accelerator module includes a pulse-forming network that delivers a voltage pulse to the module of substantially .1-1 MeV maximum energy over a time duration of less than or equal to 1 ..mu..sec.

  12. The solar gamma ray spectrum between 4 and 8 MeV

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Kozlovsky, B.; Suri, A. N.

    1976-01-01

    The properties of nuclear gamma ray emission in the 4 to 8 MeV range were evaluated. This emission consists of broad and narrow lines resulting from nuclear reactions of energetic H, He, C and O nuclei with ambient matter. Calculations were compared with observations of the 1972, August 4 flare and show that: (1) essentially all the observed radiation in the 4 to 8 MeV region is to the superposition of broad and narrow lines of nuclear origin with almost no contribution from other mechanisms; (2) the accelerated particles in the energy region from about 10 to 100 MeV/amu have a relatively flat Energy spectrum; (3) the calculated gamma ray spectrum, obtained from an isotropic distribution of accelerated particles, fits the observed spectrum better than the spectrum derived from an anisotropic distribution for which the particles' velocity vectors point towards the photosphere; and (4) it is possible to set a stringent upper limit on the ratio of relativistic electrons to protons in flares, consistent with the small, but finite, electron-to-proton ratio in galactic cosmic rays.

  13. 40 CFR 3.20 - How will EPA provide notice of changes to the Central Data Exchange?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... section, whenever EPA plans to change Central Data Exchange hardware or software in ways that would affect... the equipment, software, or services needed to transmit electronic documents to the Central...

  14. Analysis of 33 MeV Nitrogen irradiated UHMWPE

    SciTech Connect

    Grosso, Mariela del; Chappa, Veronica; Garcia Bermudez, Gerardo

    2007-10-26

    In this work, we irradiated UHMWPE with 33 MeV Nitrogen ions, at several fluences, to generate surface modifications without affecting the bulk properties. These modifications were quantified by means of wear resistance tests and Fourier transform infrared spectroscopy (FTIR) measurements. Experimental results show an optimum ion fluence value that maximizes UHMWPE wear resistance.

  15. The 400 MeV Linac Upgrade at Fermilab

    SciTech Connect

    Noble, R.J.

    1992-12-01

    The Fermilab Linac Upgrade in planned to increase the energy of the H{sup {minus}} linac from 200 to 400 MeV. This is intended to reduce the incoherent space-charge tuneshift at injection into the 8 GeV Booster which limit either the brightness or the total intensity of the beam. The Linac Upgrade will be achieved by replacing the last four 201.25 MHs drift-tube linac (DTL) tanks which accelerate the beam from 116 to 200 MeV, with seven 805 MRs side-coupled cavity modules operating at an average axial field of about 7.5 MV/meter. This will allow acceleration to 400 MeV in the existing Linac enclosure. Each accelerator module will be driven with a 12 MW klystron-based rf power supply. Three of seven accelerator modules have been fabricated, power tested and installed in their temporary location adjacent to the existing DTL. All seven RF Modulators have been completed and klystron installation has begun. Waveguide runs have completed from the power supply gallery to the accelerator modules. The new linac will be powered in the temporary position without beam in order to verify overall system reliability until the laboratory operating schedule permits final conversion to 400 MeV operation.

  16. History of the ZGS 500 MeV booster.

    SciTech Connect

    Simpson, J.; Martin; R.; Kustom, R.

    2006-05-09

    The history of the design and construction of the Argonne 500 MeV booster proton synchrotron from 1969 to 1982 is described. This accelerator has since been in steady use for the past 25 years to power the Argonne Intense Pulsed Neutron Source (IPNS).

  17. Track nanodosimetry of 20-MeV protons at 20 nm.

    PubMed

    Conte, V; Colautti, P; De Nardo, L; Ferretti, A; Poggi, M; Moro, D; Lombardi, M; Tornielli, G; Grosswendt, B

    2011-02-01

    Track nanodosimetry is the theoretical and experimental research which studies the stochastic aspects of ionisation yield produced by ionising particles in nanometric target volumes, positioned at different distances from the primary particle track. The STARTRACK experimental set-up, mounted on the +50° beam line at the Tandem-Alpi particle accelerator of Legnaro National Laboratories, has been conceived to give an experimental basis to nanodosimetric calculations. STARTRACK is a detection system able to measure the ionisation cluster-size distributions in a 20 nm propane site, by counting the electrons set in motion by different ion tracks, with the resolution of one electron. The 'sensitive volume' SV can be moved at different distances from the primary particle track (different impact parameter). Distributions of 20-MeV protons have been measured and compared with Monte Carlo calculations. PMID:21127036

  18. Regulation of a putative corticosteroid, 17, 21-dihydroxypregn-4-ene, 3, 20-one, in sea lamprey, Petromyzon marinus.

    USGS Publications Warehouse

    Roberts, Brent W.; Didier, Wes; Satbir, Rai; Johnson, Nicholas S.; Libants, Scot V.; Sang-Seon, Yun; Close, David

    2013-01-01

    In higher vertebrates, in response to stress, the hypothalamus produces corticotropin-releasing hormone (CRH), which stimulates cells in the anterior pituitary to produce adrenocorticotropic hormone (ACTH), which in turn stimulates production of either cortisol (F) or corticosterone (B) by the adrenal tissues. In lampreys, however, neither of these steroids is present. Instead, it has been proposed that the stress steroid is actually 17,21-dihydroxypregn-4-ene-3,20-dione (11-deoxycortisol; S). However, there have been no studies yet to determine its mechanism of regulation or site of production. Here we demonstrate that (1) intraperitoneal injections of lamprey-CRH increase plasma S in a dose dependent manner, (2) intraperitoneal injections of four lamprey-specific ACTH peptides at 100 lg/kg, did not induce changes in plasma S concentrations in either males or females; (3) two lamprey-specific gonadotropin-releasing hormones (GnRH I and III) and arginine-vasotocin (AVT), all at single doses, stimulated S production as well as, or to an even greater extent than CRH; (4) sea lamprey mesonephric kidneys, in vitro, converted tritiated 17a-hydroxyprogesterone (17a-P) into a steroid that had the same chromatographic properties (on HPLC and TLC) as S; (5) kidney tissues released significantly more immunoassayable S into the incubation medium than gill, liver or gonad tissues. One interpretation of these results is that the corticosteroid production of the sea lamprey, one of the oldest extant vertebrates, is regulated through multiple pathways rather than the classical HPI-axis. However, the responsiveness of this steroid to the GnRH peptides means that a reproductive rather than a stress role for this steroid cannot yet be ruled out.

  19. Portable 1,5 MeV X-Band Linac For Non-destructive Radiography

    NASA Astrophysics Data System (ADS)

    Saversky, A. J.; Rodionov, A. E.; Shaltyrev, A. P.; Shchedrin, I. S.

    1997-05-01

    Portable linear electron accelerator Y-34 developed in Small Accelerator Laboratory of MEPhI for non-destructive industrial radiography. This Linac is a fully self-contained device with the exception of external electric power 220Vx50Gz, 1 phase, 5 kVA. Full mass of Linac Y-34 - less than 300 kg. The Radiographic parameters: Nominal Energy - 1,5 MeV; Energy Range - 0,7...1,8 MeV; Maximum pulse current - 100 mA; Maximum Intensity - 15 R/min@m; Focal spot size - less than 2 mm. The Linac is comprised of 4 subassemblies. The X-ray head with weight less than 100 kg, dimensions: 0,7x0,7x1,0 m contains the traveling-wave accelerating structure with lens 0,4 m, electron gun, vacuum pump, tungsten target and RF-system with 500-kW magnetron. The permanent magnets focusing system provides focal spot less than 2 mm. The high voltage power unit consist of a line-type magnetron/electron gun modulator 2 kW power supply, the weight is equal 70 kg. The self-contained cooling water supply provides temperature controlled water for accelerator structure and magnetron. The control console allows convenient monitoring of critical system and Linac parameters by manual or remote computer. Portable X-band Linac Y-34 is the effective X - ray and/or electron beam source for such applications as non-destructive examination of nuclear reactor systems, solid rocket motors, technology research.

  20. Implementation of a compact magnetic electron energy spectrometer for intense relativistic electron beams. Interim report

    SciTech Connect

    Gregor, J.A.; Antoniades, J.A.

    1993-11-05

    A diagnostic used for measuring the energy of 1 to 5 MEV pulsed electron beams by means independent of the beam generating device is investigated. The method employed is capable of collecting the required data optically in a single pulse. The beam energy is measured using a magnetic electron spectrometer coupled with a scintillating material. Using a polaroid camera to collect data, the energy of electron beams from two field emission diode accelerators is measured. The first is a nominal 1 MEV, 16 kA, 25 ns FWHM electron beam and the second is a nominal 5 MEV, 20 kA, 50 ns FWHM electron beam. A detailed study of measurement accuracy and possible sources of error was accomplished. Energy, Relativistic, Electron beam. Electron, Spectrometer.

  1. SAMPEX and Relativistic Electron Microbursts

    NASA Astrophysics Data System (ADS)

    Blake, J. B.

    2012-12-01

    The launch of SAMPEX ushered in a new era in the study electron microbursts. Bursty electron precipitation had long been known from rocket and balloon observations but SAMPEX, with its extremely large geometric factor and rapid sampling (100 cm2-sr and 50 samples/sec for electrons > 1 MeV) has provided a far more complete and detailed view for almost two decades of nearly continuous data acquisition. Highlights of these observations will be presented.

  2. A laser-Compton scattering prototype experiment at 100 MeV linac of Shanghai Institute of Applied Physics

    NASA Astrophysics Data System (ADS)

    Luo, W.; Xu, W.; Pan, Q. Y.; Cai, X. Z.; Chen, J. G.; Chen, Y. Z.; Fan, G. T.; Fan, G. W.; Guo, W.; Li, Y. J.; Liu, W. H.; Lin, G. Q.; Ma, Y. G.; Shen, W. Q.; Shi, X. C.; Xu, B. J.; Xu, J. Q.; Xu, Y.; Zhang, H. O.; Yan, Z.; Yang, L. F.; Zhao, M. H.

    2010-01-01

    As a prototype of the Shanghai Laser Electron Gamma Source in the Shanghai Synchrotron Radiation Facility, an x-ray source based on laser-Compton scattering (LCS) has been installed at the terminal of the 100 MeV linac of the Shanghai Institute of Applied Physics. LCS x-rays are generated by interactions between Q-switched Nd:yttrium aluminum garnet laser pulses [with wavelength of 1064 nm and pulse width of 21 ns (full width at half maximum)] and electron bunches [with energy of 108 MeV and pulse width of 0.95 ns (rms)] at an angle of 42° between laser and electron beam. In order to measure the energy spectrum of LCS x-rays, a Si(Li) detector along the electron beam line axis is positioned at 9.8 m away from a LCS chamber. After background subtraction, the LCS x-ray spectrum with the peak energy of 29.1±4.4form="infix">∣stat±2.1form="infix">∣syst keV and the peak width (rms) of 7.8±2.8form="infix">∣stat±0.4form="infix">∣syst keV is observed. Normally the 100 MeV linac operates with the electron macropulse charge of 1.0 nC/pulse, and the electron and laser collision repetition rate of 20 Hz. Therefore, the total LCS x-ray flux of (5.2±2.0)×102 Hz can be achieved.

  3. Recombination in electron coolers

    NASA Astrophysics Data System (ADS)

    Wolf, A.; Gwinner, G.; Linkemann, J.; Saghiri, A. A.; Schmitt, M.; Schwalm, D.; Grieser, M.; Beutelspacher, M.; Bartsch, T.; Brandau, C.; Hoffknecht, A.; Müller, A.; Schippers, S.; Uwira, O.; Savin, D. W.

    2000-02-01

    An introduction to electron-ion recombination processes is given and recent measurements are described as examples, focusing on low collision energies. Discussed in particular are fine-structure-mediated dielectronic recombination of fluorine-like ions, the moderate recombination enhancement by factors of typically 1.5-4 found for most ion species at relative electron-ion energies below about 10 meV, and the much larger enhancement occurring for specific highly charged ions of complex electronic structure, apparently caused by low-energy dielectronic recombination resonances. Recent experiments revealing dielectronic resonances with very large natural width are also described.

  4. K-Shell Ionization of Fluorocarbons Constituents by 2.0 MeV H^+.

    NASA Astrophysics Data System (ADS)

    Moreau, C.; Williams, A. M.; Shinpaugh, J. L.; Toburen, L. H.

    1997-11-01

    Cross sections for K-shell ionization of fluorine and carbon have been measured from Auger-electron yields for 2-MeV proton impact on CH_3F, CHF_3, CF_4, C_2F_6, and C_4F_8. Ejected electrons were electrostatically analyzed for electron-emission angles from 20^circ to 125^circ with respect to the incident beam. Absolute cross sections were determined by integrating the doubly differential yields with respect to emission angle and normalizing the resulting singly differential continuum-electron yields to Rutherford energy-loss cross sections at an electron energy of 1 KeV.(L.H. Toburen, S.T. Manson, and Y. Kim, Phys. Rev. A 17), 148 (1978). While large variations (up to a factor of two) of the fluorine K-shell ionization cross section have been previously reported for ionization in different fluorine-containing molecules ionized by He^+ ions,(Ghebremedhin, Ariyasinghe, and Powers, Phys. Rev. A 53), 1537 (1996). our proton-impact results show that the cross sections per fluorine atom differ by less than 20% for the molecules investigated.

  5. Variable Energy 2-MeV S-Band Linac for X-ray and Other Applications

    SciTech Connect

    H. Bender; D. Schwellenbach; R. Sturges; R. Trainham

    2008-07-01

    This paper describes the design and operation of a compact, 2-MeV, S-band linear accelerator (linac) with variable energy tuning and short-pulse operation down to 15 ps with 100-A peak current. The design consists of a buncher cavity for short-pulse operation and two coupled resonator sections for acceleration. Single-pulse operation is accomplished through a fast injector system with a 219-MHz subharmonic buncher. The machine is intended to support a variety of applications, such as x-ray and electron beam diagnostic development, and recently, electron diffraction studies of phase transitions in shocked materials.

  6. Variable Energy 2-MeV S-Band Linac for X-ray and Other Applications

    SciTech Connect

    Howard Bender, Dave Schwellenbach, Ron Sturges, Rusty Trainham

    2008-03-01

    We will describe the design and operation of a compact, 2-MeV, S-band linear accelerator (linac) with variable energy tuning and short-pulse operation down to 15 ps with 100-A peak current. The design consists of a buncher cavity for short-pulse operation and two coupled resonator sections for acceleration. Single-pulse operation is accomplished through a fast injector system with a 219-MHz subharmonic buncher. The machine is intended to support a variety of applications, such as X-ray and electron beam diagnostic development and, recently, electron diffraction studies of phase transitions in shocked materials.

  7. High brightness sources for MeV microprobe applications

    SciTech Connect

    Read, P.M.; Alton, G.D.; Maskrey, J.T.

    1987-01-01

    State of the art MeV ion microprobe facilities are now approaching current density limitations on targets imposed by the fundamental nature of conventional gaseous ion sources. With a view to addressing this problem efforts are under way which have the ultimate objective of developing high brightness Li liquid metal ion sources suitable for MeV ion microprobe applications. Prototype Li/sup +/ and Ga/sup +/ liquid metal ion sources have been designed, fabricated and are undergoing preliminary testing. This paper describes the first total emittance and brightness measurements of a Ga liquid metal ion source. The effect of the geometry of the ion extraction system is investigated and the brightness data are compared to those of a radio frequency ion source.

  8. Magnifying lens for 800 MeV proton radiography

    SciTech Connect

    Merrill, F. E.; Campos, E.; Espinoza, C.; Hogan, G.; Hollander, B.; Lopez, J.; Mariam, F. G.; Morley, D.; Morris, C. L.; Murray, M.; Saunders, A.; Schwartz, C.; Thompson, T. N.

    2011-10-15

    This article describes the design and performance of a magnifying magnetic-lens system designed, built, and commissioned at the Los Alamos National Laboratory (LANL) for 800 MeV flash proton radiography. The technique of flash proton radiography has been developed at LANL to study material properties under dynamic loading conditions through the analysis of time sequences of proton radiographs. The requirements of this growing experimental program have resulted in the need for improvements in spatial radiographic resolution. To meet these needs, a new magnetic lens system, consisting of four permanent magnet quadrupoles, has been developed. This new lens system was designed to reduce the second order chromatic aberrations, the dominant source of image blur in 800 MeV proton radiography, as well as magnifying the image to reduce the blur contribution from the detector and camera systems. The recently commissioned lens system performed as designed, providing nearly a factor of three improvement in radiographic resolution.

  9. Detector blur associated with MeV radiographic imaging systems

    NASA Astrophysics Data System (ADS)

    Baker, Stuart A.; Lutz, Stephen S.; Smalley, Duane D.; Brown, Kristina K.; Danielson, Jeremy; Haines, Todd J.; Howe, Russell A.; Mitchell, Stephen E.; Morgan, Dane; Schultz, Larry J.

    2015-08-01

    We are investigating scintillator performance in radiographic imaging systems at x-ray endpoint energies of 0.4 and 2.3 MeV in single-pulse x-ray machines. The effect of scene magnification and geometric setup will be examined along with differences between the detector response of radiation and optical scatter. Previous discussion has reviewed energy absorption and efficiency of various imaging scintillators with a 2.3 MeV x-ray source. The focal point of our study is to characterize scintillator blur to refine system models. Typical detector geometries utilize thin tiled LYSO:Ce (cerium-doped lutetium yttrium orthosilicate) assembled in a composite mosaic. Properties of individual tiles are being studied to understand system resolution effects present in the experimental setup. Comparison of two different experiments with different geometric configurations is examined. Results are then compared to different scene magnifications generated in a Monte-Carlo simulation.

  10. Evolution of the 400 MeV linac design

    SciTech Connect

    MacLachlan, J.A.

    1987-11-09

    The basic premises of the conceptual design for the linac upgrade are pursued to establish lengths, gradients, power dissipation, etc., for the 400 MeV linac and matching section. The discussion is limited to accelerating and focusing components. Wherever values depend on the choice of the accelerating structure, the disk-and-washer structure is emphasized; the results are generally relevant to the side coupled cavity choice also.

  11. MeV neutrinos in double {beta} decay

    SciTech Connect

    Zuber, K.

    1997-08-01

    The effect of Majorana neutrinos in the MeV mass range on the double {beta} decay of various isotopes is studied on pure phenomenological arguments. By using only experimental half-life data, limits on the mixing parameter U{sub eh}{sup 2} of the order 10{sup {minus}7} can be derived. Also the possible achievements of upcoming experiments and some consequences are outlined. {copyright} {ital 1997} {ital The American Physical Society}

  12. Electron Cooling of RHIC

    SciTech Connect

    I. Ben-Zvi; D.S. Barton; D.B. Beavis; M. Blaskiewicz; J.M. Brennan; A. Burrill; R. Calaga; P. Cameron; X.Y. Chang; R. Connolly; Yu.I. Eidelman; A.V. Fedotov; W. Fischer; D.M. Gassner; H. Hahn; M. Harrison; A. Hershcovitch; H.-C. Hseuh; A.K. Jain; P.D.J. Johnson; D. Kayran; J. Kewisch; R.F. Lambiase; V. Litvinenko; W.W. MacKay; G.J. Mahler; N. Malitsky; G.T. McIntyre; W. Meng; K.A.M. Mirabella; C. Montag; T.C.N. Nehring; T. Nicoletti; B. Oerter; G. Parzen; D. Pate; J. Rank; T. Rao; T. Roser; T. Russo; J. Scaduto; K. Smith; D. Trbojevic; G. Wang; J. Wei; N.W.W. Williams; K.-C. Wu; V. Yakimenko; A. Zaltsman; Y. Zhao; D.T. Abell; D.L. Bruhwiler; H. Bluem; A. Burger; M.D. Cole; A.J. Favale; D. Holmes; J. Rathke; T. Schultheiss; A.M.M. Todd; A.V. Burov; S. Nagaitsev; J.R. Delayen; Y.S. Derbenev; L. W. Funk; P. Kneisel; L. Merminga; H.L. Phillips; J.P. Preble; I. Koop; V.V. Parkhomchuk; Y.M. Shatunov; A.N. Skrinsky; I. Koop; V.V. Parkhomchuk; Y.M. Shatunov; A.N. Skrinsky; J.S. Sekutowicz

    2005-05-16

    We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.agsrhichome.bnl.gov/eCool/.

  13. Development of a 20-MeV Dielectric-Loaded Accelerator Test Facility

    SciTech Connect

    Gold, S.H.; Kinkead, A.K.; Gai, W.; Power, J.G.; Konecny, R.; Jing, C.G.; Tantawi, S.G.; Nantista, C.D.; Hu, Y.; Chen, H.; Tang, C.; Lin, Y.; Bruce, R.W.; Bruce, R.L.; Fliflet, A.W.; Lewis, D.; /Naval Research Lab, Wash., D.C. /LET Corp., Washington /Argonne /SLAC /Tsinghua U., Beijing

    2005-06-22

    This paper describes a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded accelerator (DLA) test facility powered by a high-power 11.424-GHz magnicon amplifier. The magnicon can presently produce 25 MW of output power in a 250-ns pulse at 10 Hz, and efforts are in progress to increase this to 50 MW. The facility will include a 5 MeV electron inector being developed by the Accelerator Laboratory of Tsinghua University in Beijing, China. The DLA test structures are being developed by ANL, and some have undergone testing at NRL at gradients up to {approx} 8 MV/m. SLAC is developing a means to combine the two magnicon output arms, and to drive an injector and accelerator with separate control of the power ratio and relative phase. RWBruce Associates, Inc., working with NRl, is developing a means to join short ceramic sections into a continuous accelerator tube by ceramic brazing using an intense millimeter-wave beam. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA structure, and spectrometer, should take place within the next year. The facility will be used for testing DLA structures using a variety of materials and configurations, and also for testing other X-band accelerator concepts. The initial goal is to produce a compact 20 MeV dielectric-loaded test accelerator.

  14. Detectable MeV neutrinos from black hole neutrino-dominated accretion flows

    NASA Astrophysics Data System (ADS)

    Liu, Tong; Zhang, Bing; Li, Ye; Ma, Ren-Yi; Xue, Li

    2016-06-01

    Neutrino-dominated accretion flows (NDAFs) around rotating stellar-mass black holes (BHs) have been theorized as the central engine of relativistic jets launched in massive star core collapse events or compact star mergers. In this work, we calculate the electron neutrino/antineutrino spectra of NDAFs by fully taking into account the general relativistic effects, and investigate the effects of viewing angle, BH spin, and mass accretion rate on the results. We show that even though a typical NDAF has a neutrino luminosity lower than that of a typical supernova (SN), it can reach 1050- 1051 erg s-1 peaking at ˜10 MeV , making NDAFs potentially detectable with the upcoming sensitive MeV neutrino detectors if they are close enough to Earth. Based on the observed gamma-ray burst (GRB) event rate in the local universe and requiring that at least three neutrinos are detected to claim a detection, we estimate a detection rate up to ˜(0.10 - 0.25 ) per century for GRB-related NDAFs by the Hyper-Kamiokande (Hyper-K) detector if one neglects neutrino oscillation. If one assumes that all type Ib/c SNe have an engine-driven NDAF, the Hyper-K detection rate would be ˜(1 - 3 ) per century. By considering neutrino oscillations, the detection rate may decrease by a factor of 2-3. Detecting one such event would establish the observational evidence of NDAFs in the Universe.

  15. Status of the 1 MeV Accelerator Design for ITER NBI

    SciTech Connect

    Kuriyama, M.; Boilson, D.; Hemsworth, R.; Svensson, L.; Graceffa, J.; Schunke, B.; Decamps, H.; Tanaka, M.; Bonicelli, T.; Masiello, A.

    2011-09-26

    The beam source of neutral beam heating/current drive system for ITER is needed to accelerate the negative ion beam of 40A with D{sup -} at 1 MeV for 3600 sec. In order to realize the beam source, design and R and D works are being developed in many institutions under the coordination of ITER organization. The development of the key issues of the ion source including source plasma uniformity, suppression of co-extracted electron in D beam operation and also after the long beam duration time of over a few 100 sec, is progressed mainly in IPP with the facilities of BATMAN, MANITU and RADI. In the near future, ELISE, that will be tested the half size of the ITER ion source, will start the operation in 2011, and then SPIDER, which demonstrates negative ion production and extraction with the same size and same structure as the ITER ion source, will start the operation in 2014 as part of the NBTF. The development of the accelerator is progressed mainly in JAEA with the MeV test facility, and also the computer simulation of beam optics also developed in JAEA, CEA and RFX. The full ITER heating and current drive beam performance will be demonstrated in MITICA, which will start operation in 2016 as part of the NBTF.

  16. Elastic Compton Scattering from the Deuteron Near 100 MeV

    NASA Astrophysics Data System (ADS)

    Kovash, Michael; Shoniyozov, Khayrullo; Compton@MAX-lab Collaboration

    2015-10-01

    Differential cross sections for elastic Compton scattering from targets of carbon and deuterium have been measured from 86 to 113 MeV using a tagged bremsstrahlung beam at the MAX 1 electron storage ring in Lund, Sweden. Photon spectra were collected in 2009 and 2010 at scattering angles of 60, 120 and 150 degrees using three very large, high efficiency NaI spectrometers, each with a FWHM resolution of approximately 2 MeV. The deuterium target consisted of a cryogenic liquid cell of 17 cm length. Improvements made to the running conditions of previous MAX-lab data sets include the use of multi-hit time digitizers, and reduced instantaneous counting rates in both the tagging and the NaI detectors. GEANT4 simulations have been used to determine the photon detector response and efficiency, as well as the photon losses in the targets. The overall accuracy of this procedure is verified by comparing the current carbon results with previous data. The new deuterium cross sections will be presented and compared with the earlier results from this collaboration. The combined data set will be compared with recent Chiral Effective Field Theory calculations to determine the values of the neutron polarizabilities, αn and βn.

  17. Study of beamlet deflection and its compensations in a MeV accelerator

    SciTech Connect

    Kashiwagi, Mieko; Inoue, Takashi; Taniguchi, Masaki; Umeda, Naotaka; Dairaku, Masayuki; Takemoto, Jumpei; Tobari, Hiroyuki; Tsuchida, Kazuki; Watanabe, Kazuhiro; Yamanaka, Haruhiko; Sakamoto, Keishi; Grisham, Larry R.

    2011-09-26

    In a five stage multi-aperture and multi-grid (MAMuG) accelerator in JAEA, beam acceleration tests are in progress toward 1 MeV, 200 A/m{sup 2} H{sup -} ion beams for ITER. The 1 MV voltage holding has been successfully demonstrated for 4,000 s with the accelerator of expanded gap length that lowered local electric field concentrations. This led to increase of the beam energy up to 900 keV-level. However, it was found that beamlets were deflected more in long gaps and direct interceptions of the deflected beamlet caused breakdowns. The beamlet deflection and its compensation methods were studied utilizing a three-dimensional multi beamlet analysis. The analysis showed that the 1 MeV beam can be compensated by a combination of the aperture offset of 0.8 mm applied in the electron suppression (ESG) and the metal bar called a field shaping plate with a thickness of 1 mm attached beneath the ESG. The paper reports these compensation methods and analytical predictions, with experimental results of the MAMuG accelerator in which those compensation techniques have been applied.

  18. Design and construction of the 3.2 MeV high voltage column for DARHT II

    SciTech Connect

    Peters, C., Elliott, B.; Yu, S.; Eylon, S.; Henestroza, E.

    2000-08-20

    A 3.2 MeV injector has been designed and built for the DARHT II Project at Los Alamos Lab. The installation of the complete injector system is nearing completion at this time. The requirements for the injector are to produce a 3.2 MeV, 2000-ampere electron pulse with a flattop width of at least 2-microseconds and emittance of less than 0.15 pi cm-rad normalized. A large high voltage column has been built and installed. The column is vertically oriented, is 4.4 meters long, 1.2 meters in diameter, and weighs 5700 kilograms. A novel method of construction has been employed which utilizes bonded Mycalex insulating rings. This paper will describe the design, construction, and testing completed during construction. Mechanical aspects of the design will be emphasized.

  19. Design and Construction of the 3.2-MeV Cathode Assembly for DARHT-II

    NASA Astrophysics Data System (ADS)

    Peters, Craig

    A 3.2 MeV injector has been designed and built for the Darht II Project at Los Alamos Lab. The installation of the complete injector system is nearing completion at this time. The requirements for the injector are to produce a 3.2 MeV, 2000 ampere electron pulse with a flattop width of at least 2-microseconds and emittance of less than 0.15 p cm-rad normalized. A 16.5 cm diameter hot emitter cathode is used. This paper will describe the design and fabrication of major Cathode Assembly components and test performance of subsystems to date. Mechanical and thermal issues will be emphasized. More detailed discussion of the active alignment system used to maintain the stringent cathode alignment requirement.

  20. LIGHT SOURCE: Physical design of a 10 MeV LINAC for polymer radiation processing

    NASA Astrophysics Data System (ADS)

    Feng, Guang-Yao; Pei, Yuan-Ji; Wang, Lin; Zhang, Shan-Cai; Wu, Cong-Feng; Jin, Kai; Li, Wei-Min

    2009-06-01

    In China, polymer radiation processing has become one of the most important processing industries. The radiation processing source may be an electron beam accelerator or a radioactive source. Physical design of an electron beam facility applied for radiation crosslinking is introduced in this paper because of it's much higher dose rate and efficiency. Main part of this facility is a 10 MeV travelling wave electron linac with constant impedance accelerating structure. A start to end simulation concerning the linac is reported in this paper. The codes Opera-3d, Poisson-superfish and Parmela are used to describe electromagnetic elements of the accelerator and track particle distribution from the cathode to the end of the linac. After beam dynamic optimization, wave phase velocities in the structure have been chosen to be 0.56, 0.9 and 0.999 respectively. Physical parameters about the main elements such as DC electron gun, iris-loaded periodic structure, solenoids, etc, are presented. Simulation results proves that it can satisfy the industrial requirement. The linac is under construction. Some components have been finished. Measurements proved that they are in a good agreement with the design values.

  1. Cross sections and analyzing powers of sup 15 N(p,n) sup 15 O at 200 MeV and 494 MeV

    SciTech Connect

    Ciskowski, D.E. )

    1989-11-01

    Differential cross sections and analyzing powers have been measured for the {sup 15}N(p,n){sup 15} O(g.s.) reaction at bombarding energies of 200 MeV and 494 MeV. The 494 MeV data were obtained at the LAMPF Neutron Time-Of-Flight Facility on an 82 m flight path with a resolution of about 2.7 MeV. The 200 MeV data were obtained at IUCF on a 76m flight path with a resolution of about 1.1 MeV. At both energies, the measured analyzing power is small, the magnitude is less than .2 for momentum transfers of less than 1 fm{sup {minus}1}. In contrast, both Relativistic and standard DWIA calculations predict a maximum of A={minus}.7 near q=0.7 fm{sup {minus}1}. 53 refs., 44 figs.

  2. CRRES Medium Electrons A results

    NASA Astrophysics Data System (ADS)

    Vampola, A. L.

    1996-07-01

    The CRRES Medium Electrons A spectrometer data were used to examine the dynamics of electron fluxes in the inner zone after a series of magnetic storms increased electron fluxes by an order of magnitude down to as low as L=1.25. Comparisons of CRRES electron data with the AE8MAX particle model show good agreement in the inner zone in flux intensity, energy spectra, and pitch angle distributions up to about 600 keV pre-storm. Above 600 keV, the AE8MAX model has higher fluxes. The maximum energy spectrum over the range 0.15 MeV to 1.7 MeV observed at geosynchronous orbit altitude during the 16-month CRRES mission is presented and extrapolated to 10 MeV. The combined spectrum is characterized as the sum of three power-law segments with breakpoints at 0.8 and 2.0 MeV. The coefficients for the three segments are respectively NE=5×107E-1.5, NE=4.5×1010E-2.5, and NE=4×1015E-4. Shielding of 155 mils Al equivalent would be required to prevent deep dielectric charging problems on geosynchronous satellites by an environment as severe as this maximum spectrum.

  3. 17O(n,α)14C cross section from 25 meV to approximately 1 MeV

    NASA Astrophysics Data System (ADS)

    Koehler, P. E.; Graff, S. M.

    1991-12-01

    We have measured the 17O(n,α)14C cross section from thermal energy to approximately 1 MeV. A bump in the data near 3 keV could be fitted by a state whose properties are consistent with a known subthreshold J π=1- level at Ex=8.039 MeV. The cause of the 1/v cross section near thermal energy could not be determined although the known 2+ state at 8.213 MeV was found to be too narrow to contribute much to the thermal cross section. Our data are compared to measurements made via the inverse reaction. There are many differences between the two sets of data. The astrophysical reaction rate was calculated from the measured cross section. This reaction plays a role in the nucleosynthesis of heavy elements in nonstandard big-bang models. At big-bang temperatures, the experimental rate was found to be in fair agreement with the rate estimated from the previously known properties of states of 18O in this region. Furthermore, using the available information from experiments, it was estimated that the 17O(n,α)14C rate is approximately a factor of 103-104 times larger than the 17O(n,γ)18O rate at big-bang temperatures. As a result, there may be significant cycling between 14C and 17O resulting in a reduction of heavy-element nucleosynthesis.

  4. Conformational analysis of 20-keto steroids. Single-crystal X-ray structure analysis of 16 alpha,17-epoxy-4-pregnene-3,20-dione.

    PubMed

    Goubitz, K; Schenk, H; Zeelen, F J

    1984-08-01

    The structure of 16 alpha,17-epoxy-4-pregnene-3,20-dione was determined. The 20-carbonyl group eclipses the C(13)-C(17) bond. No direct correlation between the observed structure and its progestational activity could be inferred from our investigation. PMID:6537049

  5. Measurements of the Argonne Wakefield Accelerator's low charge, 4 MeV RF photocathode witness beam.

    SciTech Connect

    Power, J.

    1998-04-01

    The Argonne Wakefield Accelerator's (AWA) witness RF photocathode gun produced its first electron beam in April of 1996. We have characterized the charge, energy, emittance and bunch length of the witness beam over the last several months. The emittance Was measured by both a quad scan that fitted for space charge using an in house developed Mathematica routine and a pepper pot technique. The bunch length was measured by imaging Cherenkov light from a quartz plate to a Hamamatsu streak camera with 2 psec resolution. A beam energy of 3.9 Mev was measured with a 6 inch round pole spectrometer while a beam charge was measured with both an ICT and a Faraday Cup. Although the gun will normally be run at 100 pC it has produced charges from 10 pC to 4 nc. All results of the measurements to date are presented here.

  6. Measurement of stopping power ratios for 60 MeV positive or negative pions.

    PubMed

    Nordin, J A; Henkelman, R M

    1979-07-01

    Pion stopping power ratios are essential parameters for pion radiotherapy treatment planning. The validity of scaling proton stopping powers to pions is called into question since the pion mass is intermediate between the electron and proton masses. Direct measurements of stopping power ratios with respect to water were made for 60 MeV pions of both charges in Teflon, Plexiglas, nylon, paraffin, gelatine, tissue-equivalent plastic (Shonka A150), graphite, aluminium, steel and copper. Corrections for multiple scattering and energy dependence of the stopping power are applied. Measured stopping power ratios at an accuracy of 0.6% are in agreement to within the limits of experimental error with stopping power ratios calculated from the Bethe-Bloch equation using elemental I-values and Bragg additivity. PMID:112597

  7. Liquid xenon time projection chamber for gamma rays in the MeV region: Development status

    NASA Technical Reports Server (NTRS)

    Aprile, E.; Bolotnikov, A.; Chen, D.; Mukherjee, R.

    1992-01-01

    The feasibility of a large volume Liquid Xenon Time Projection Chamber (LXe-TPC) for three dimensional imaging and spectroscopy of cosmic gamma ray sources, was tested with a 3.5 liter prototype. The observation of induction signals produced by MeV gamma rays in liquid xenon is reported, with a good signal-to-noise ratio. The results represent the first experimental demonstration with a liquid xenon ionization chamber of a nondestructive readout of the electron image produced by point-like charges, using a sense wire configuration of the type originally proposed in 1970 by Gatti et al. An energy resolution as good as that previously measured by the millimeter size chambers, was achieved with the large prototype of 4.4 cm drift gap.

  8. New results from RENO and the 5 MeV excess

    NASA Astrophysics Data System (ADS)

    Seo, Seon-Hee

    2015-07-01

    One of the main goals of RENO (Reactor Experiment for Neutrino Oscillation) is to measure the smallest neutrino mixing angle θ13 using reactor neutrinos in Korea. RENO is the first reactor experiment taking data with two identical detectors in different locations (Near and Far), which is critical to reduce systematic uncertainty in reactor neutrino flux. Our data taking has been almost continuous since Aug. 2011 and we have collected about 434,000 (54,000) electron anti-neutrinos in the Near (Far) detector by 2013. Using this data (about 800 live days) we present a new result on θ13: sin22θ13 = 0.101 ± 0.008 (stat.) ± 0.010 (syst.). We also report the 5 MeV excess present in the prompt signal spectrum in our data, and its correlation with our reactor thermal power.

  9. Charge neutralized low energy beam transport at Brookhaven 200 MeV linac

    NASA Astrophysics Data System (ADS)

    Raparia, D.; Alessi, J.; Atoian, G.; Zelenski, A.

    2016-02-01

    The H- magnetron source provides about 100 mA H- beam to be match into the radio-frequency quadrupole accelerator. As H- beam traverses through low energy transport, it ionizes the residual gas and electrons are repelled and positive ions are trapped in the beam, due to negative potential of the beam, providing charge neutralization for the H- beam. The neutralization time for the critical density depends upon the background gas and its pressure. Critical density for xenon gas at 35 keV is about 43 times smaller than that of hydrogen and stripping cross section is only 5 times than that of hydrogen gas. We are using xenon gas to reduce neutralization time and to improve transmission through the 200 MeV linac. We are also using pulse nitrogen gas to improve transmission and stability of polarized H- beam from optically pumped polarized ion source.

  10. Electrosphere of macroscopic 'quark nuclei': A source for diffuse MeV emissions from dark matter

    SciTech Connect

    Forbes, Michael McNeil; Lawson, Kyle; Zhitnitsky, Ariel R.

    2010-10-15

    Using a Thomas-Fermi model, we calculate the structure of the electrosphere of the quark antimatter nuggets postulated to comprise much of the dark matter. This provides a single self-consistent density profile from ultrarelativistic densities to the nonrelativistic Boltzmann regime that we use to present microscopically justified calculations of several properties of the nuggets, including their net charge, and the ratio of MeV to 511 keV emissions from electron annihilation. We find that the calculated parameters agree with previous phenomenological estimates based on the observational supposition that the nuggets are a source of several unexplained diffuse emissions from the Galaxy. As no phenomenological parameters are required to describe these observations, the calculation provides another nontrivial verification of the dark-matter proposal. The structure of the electrosphere is quite general and will also be valid at the surface of strange-quark stars, should they exist.

  11. The electrosphere of macroscopc ""nuclei"": diffuse emissions in the MeV band from dark antimatter

    SciTech Connect

    Forbes, Michael Mcneil; Lawson, Kyle; Zhitnitsky, Ariel R

    2009-01-01

    Using a Thomas-Fermi model, we calculate the structure of the electrosphere of the quark antimatter nuggets postulated to comprise much of the dark matter. This provides a single self-consistent density profile from ultra-rel ativistic densities to the non-relativistic Boltzmann regime. We use this to present a microscopically justified calculation of several properties of the nuggets, including their net charge, and the ratio of MeV to 511 keV emissions from electron annihilation. We find that the calculated parameters agree with previous phenomenological estimates based on the observational supposition that the nuggets are a source of several unexplained diffuse emissions from the galaxy. This provides another nontrivial verification of the dark matter proposal. The structure of the electrosphere is quite general and will also be valid at the surface of strange-quark stars, should they exist.

  12. Dose and doping dependence of damage annealing in Fe MeV implanted InP

    SciTech Connect

    Carnera, A.; Fraboni, B.; Gasparotto, A. |; Priolo, F. |; Camporese, A.; Rossetto, G.; Frigeri, C.; Cassa, A.

    1996-12-31

    High energy (2 MeV) ion implantation of Fe in InP has been investigated by means of Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM) and secondary ions mass spectrometry (SIMS). The implanted doses ranged between 5 {times} 10{sup 13} and 5 {times} 10{sup 14} at/cm{sup 2}. Annealing in the 650--800 C range was performed and the primary as well as secondary damage evolution has been studied. The correlations between defect structure and Fe redistribution properties have been carefully analyzed. The results show the role of the primary defect structure in determining the annealing properties, both for damage recovery and Fe redistribution. The latter is also influenced by the doping of the substrate.

  13. Comparison of experimental and computational neutron spectroscopy at a 14 MeV neutron generator facility

    NASA Astrophysics Data System (ADS)

    Waller, Edward; Cousins, Tom; Desrosiers, Marc; Jones, Trevor; Buhr, Rob; Rambousky, Ronald

    2009-05-01

    At any neutron production facility, the energy spectrum at any meaningful distance from the target will be modified. For the case of a facility used to provide reference irradiations of electronics and other devices at various target-to-device distances it is important to have knowledge of these spectral modifications. In addition, it is desirable to have the ability to generate near real-time measurement capability. Advances in neutron metrology have made it possible to determine neutron energy spectra in real time to high levels of accuracy. This paper outlines a series of experimental measurements and theoretical calculations designed to quantify the scattering effects for a 14 MeV neutron generator facility, and makes appropriate recommendations for near real-time measurements of these fields.

  14. Charge neutralized low energy beam transport at Brookhaven 200 MeV linac.

    PubMed

    Raparia, D; Alessi, J; Atoian, G; Zelenski, A

    2016-02-01

    The H(-) magnetron source provides about 100 mA H(-) beam to be match into the radio-frequency quadrupole accelerator. As H(-) beam traverses through low energy transport, it ionizes the residual gas and electrons are repelled and positive ions are trapped in the beam, due to negative potential of the beam, providing charge neutralization for the H(-) beam. The neutralization time for the critical density depends upon the background gas and its pressure. Critical density for xenon gas at 35 keV is about 43 times smaller than that of hydrogen and stripping cross section is only 5 times than that of hydrogen gas. We are using xenon gas to reduce neutralization time and to improve transmission through the 200 MeV linac. We are also using pulse nitrogen gas to improve transmission and stability of polarized H(-) beam from optically pumped polarized ion source. PMID:26932107

  15. The Jovian electron spectrum: 1978-1984

    NASA Technical Reports Server (NTRS)

    Moses, D.; Evenson, P. A.; Meyer, P.

    1985-01-01

    Observations of Jovian electrons through six consecutive 13-month Jovian synodic periods from 1978 to 1984 have been made by the University of Chicago electron spectrometer onboard the ISEE-3 (ICE) spacecraft. The Jovian electron spectrum was determined from 5 to 30 Mev and was found to have a shape which is not a power law in kinetic energy, but cuts off at approximately 30 MeV. The average shape of the spectrum over each of the six intervals of best magnetic connection remains the same for all intervals within uncertainties.

  16. Validation of the GEANT4 simulation of bremsstrahlung from thick targets below 3 MeV

    NASA Astrophysics Data System (ADS)

    Pandola, L.; Andenna, C.; Caccia, B.

    2015-05-01

    The bremsstrahlung spectra produced by electrons impinging on thick targets are simulated using the GEANT4 Monte Carlo toolkit. Simulations are validated against experimental data available in literature for a range of energy between 0.5 and 2.8 MeV for Al and Fe targets and for a value of energy of 70 keV for Al, Ag, W and Pb targets. The energy spectra for the different configurations of emission angles, energies and targets are considered. Simulations are performed by using the three alternative sets of electromagnetic models that are available in GEANT4 to describe bremsstrahlung. At higher energies (0.5-2.8 MeV) of the impinging electrons on Al and Fe targets, GEANT4 is able to reproduce the spectral shapes and the integral photon emission in the forward direction. The agreement is within 10-30%, depending on energy, emission angle and target material. The physics model based on the Penelope Monte Carlo code is in slightly better agreement with the measured data than the other two. However, all models over-estimate the photon emission in the backward hemisphere. For the lower energy study (70 keV), which includes higher-Z targets, all models systematically under-estimate the total photon yield, providing agreement between 10% and 50%. The results of this work are of potential interest for medical physics applications, where knowledge of the energy spectra and angular distributions of photons is needed for accurate dose calculations with Monte Carlo and other fluence-based methods.

  17. MeV proton flux predictions near Saturn's D ring

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Roussos, E.; Kotova, A.; Cooper, J. F.; Mitchell, D. G.; Krupp, N.; Paranicas, C.

    2015-10-01

    Radiation belts of MeV protons have been observed just outward of Saturn's main rings. During the final stages of the mission, the Cassini spacecraft will pass through the gap between the main rings and the planet. Based on how the known radiation belts of Saturn are formed, it is expected that MeV protons will be present in this gap and also bounce through the tenuous D ring right outside the gap. At least one model has suggested that the intensity of MeV protons near the planet could be much larger than in the known belts. We model this inner radiation belt using a technique developed earlier to understand Saturn's known radiation belts. We find that the inner belt is very different from the outer belts in the sense that its intensity is limited by the densities of the D ring and Saturn's upper atmosphere, not by radial diffusion and satellite absorption. The atmospheric density is relatively well constrained by EUV occultations. Based on that we predict an intensity in the gap region that is well below that of the known belts. It is more difficult to do the same for the region magnetically connected to the D ring since its density is poorly constrained. We find that the intensity in this region can be comparable to the known belts. Such intensities pose no hazard to the mission since Cassini would only experience these fluxes on timescales of minutes but might affect scientific measurements by decreasing the signal-to-contamination ratio of instruments.

  18. Electron beam sterilisation of heterogeneous medical devices

    NASA Astrophysics Data System (ADS)

    Sadat, T.; Morisseau, MrD.; Ross, MissA.

    1993-07-01

    Electron beam radiation is used in the sterilisation of medical disposable devices. High energy, 10 MeV, electron beam linear accelerators are in use worldwide for this purpose. The dose distribution achieved in the products treated influences the efficiency of treatment. This paper looks at the dose distribution achieved with such machines and the methods used to define it in heterogeneous products.

  19. Relativistic attosecond electron pulses from cascaded acceleration using ultra-intense radially polarized laser beams

    NASA Astrophysics Data System (ADS)

    Varin, Charles; Fortin, Pierre-Louis; Piché, Michel

    Attosecond electron pulses with peak energy above 200 MeV could be produced with ultrafast 100-TW radially polarized laser beams in a two-stage configuration. Such electron beams would be collimated and potentially quasi-monoenergetic.

  20. Polarization observables in deuteron photodisintegration below 360 MeV

    SciTech Connect

    Glister, J.; Ron, G.; Lee, B. W.; Gilman, R.; Sarty, A. J.; Strauch, S.; Higinbotham, D. W.; Piasetzky, E.; Allada, K.; Armstrong, W.; Arrington, J.; Arenhövel, H.; Beck, A.; Benmokhtar, F.; Berman, B. L.; Boeglin, W.; Brash, E.; Camsonne, A.; Calarco, J.; Chen, J. P.; Choi, S.; Chudakov, E.; Coman, L.; Craver, B.; Cusanno, F.; Dumas, J.; Dutta, C.; Feuerbach, R.; Freyberger, A.; Frullani, S.; Garibaldi, F.; Hansen, J. -O.; Holmstrom, T.; Hyde, C. E.; Ibrahim, H.; Ilieva, Y.; de Jager, C. W.; Jiang, X.; Jones, M. K.; Kang, Hyekoo; Kelleher, A.; Khrosinkova, E.; Kuchina, E.; Kumbartzki, G.; LeRose, J. J.; Lindgren, R.; Markowitz, P.; May-Tal Beck, S.; McCullough, E.; Meekins, D.; Meziane, M.; Meziani, Z. -E.; Michaels, R.; Moffit, B.; Norum, B. E.; Oh, Y.; Olson, M.; Paolone, M.; Paschke, K.; Perdrisat, C. F.; Potokar, M.; Pomatsalyuk, R.; Pomerantz, I.; Puckett, A.; Punjabi, V.; Qian, X.; Qiang, Y.; Ransome, R. D.; Reyhan, M.; Roche, J.; Rousseau, Y.; Saha, A.; Sawatzky, B.; Schulte, E.; Schwamb, M.; Shabestari, M.; Shahinyan, A.; Shneor, R.; Širca, S.; Slifer, K.; Solvignon, P.; Song, J.; Sparks, R.; Subedi, R.; Urciuoli, G. M.; Wang, K.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Zhan, X.; Zhu, X.

    2011-02-03

    We performed high precision measurements of induced and transferred recoil proton polarization in d($\\vec{γ}$, $\\vec{p}$)n for photon energies of 277--357 MeV and θcm = 20 ° -- 120 °. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. Moreover, at the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used.

  1. The 14 MeV Frascati neutron generator

    NASA Astrophysics Data System (ADS)

    Martone, M.; Angelone, M.; Pillon, M.

    1994-09-01

    The 14-MeV Frascati neutron generator (FNG) uses the T(d, n)α fusion reaction to produce 5.0 × 10 11 n/s. In FNG a beam of deuterons is accelerated up to 300 keV by means of a linear electrostatic tube and directed onto a tritiated-titanium target containing 37 × 10 10 Bq of tritium. This paper describes the FNG facility and its auxiliary apparatus as well as the neutron source calibration performed using the associated α-particle method.

  2. A 600 MeV cyclotron for radioactive beam production

    SciTech Connect

    Clark, D.J.

    1993-05-17

    The magnetic field design for a 600 MeV proton cyclotron is described. The cyclotron has a single stage, a normal conducting magnet coil and a 9.8 m outside yoke diameter. It has 8 sectors, with a transition to 4 sectors in the center region. The magnetic field design was done using 1958 Harwell rectangular ridge system measurements and was compared with recent 3-dimensional field calculations with the program TOSCA at NSCL. The center region 4--8 sector transition focussing was also checked with TOSCA.

  3. Polarization observables in deuteron photodisintegration below 360 MeV

    SciTech Connect

    Glister, Jacqueline; Lee, Byungwuek; Gilman, R; Sarty, Adam; Strauch, Steffen; Higinbotham, Douglas; Piasetzky, Eliazer; Allada, Kalyan; Armstrong, Whitney; Arrington, John; Beck, Arie; Benmokhtar, Fatiha; Berman, Barry; Boeglin, Werner; Brash, Edward; Camsonne, Alexandre; Calarco, John; Chen, Jian-Ping; Choi, Seonho; Chudakov, Eugene; Coman, Luminita; Craver, Brandon; Cusanno, Francesco; Dumas, Jonathan; Dutta, Chiranjib; Feuerbach, Robert; Freyberger, Arne; Frullani, Salvatore; Garibaldi, Franco; Hansen, Jens-Ole; Holmstrom, Timothy; Hyde, Charles; Ibrahim, Hassan; Ilieva, Yordanka; De Jager, Cornelis; Jiang, Xiaodong; Jones, Mark; Kang, Hoyoung; Kelleher, Aidan; Khrosinkova, Elena; Kuchina, Elena; Kumbartzki, Gerfried; LeRose, John; Lindgren, Richard; Markowitz, Pete; Beck, S. May-Tal; McCullough, Emily; Meekins, David; Meziane, Mehdi; Meziane, Zein-Eddine; Michaels, Robert; Moffit, Bryan; Norum, Blaine; Oh, Yongseok; Olson, Michael; Paolone, Michael; Paschke, Kent; Perdrisat, Charles; Potokar, Milan; Pomatsalyuk, Roman; Pomerantz, Ishay; Puckett, Andrew; Punjabi, Vina; Qian, Xin; Qiang, Yi; Ransome, Ronald; Reyhand, Meral; Roche, Julie; Rousseau, Yannick; Saha, Arunava; Sawatzky, Bradley; Schulte, Elaine; Hashemi Shabestari, Mitra; Shahinyan, Albert; Shneor, R; Sirca, Simon; Slifer, Karl; Solvignon, Patricia; Song, JeongSeog; Sparks, Rachel; Subedi, Ramesh; Urciuoli, Guido; Wang, Kebin; Wojtsekhowski, Bogdan; Yan, Xinhu; Yao, Huan; Zhan, Xiaohui

    2011-03-01

    High precision measurements of induced and transferred recoil proton polarization in d(polarized gamma, polarized p})n have been performed for photon energies of 277--357 MeV and theta_cm = 20 degrees -- 120 degrees. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. At the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used.

  4. Polarization observables in deuteron photodisintegration below 360 MeV

    DOE PAGESBeta

    Glister, J.; Ron, G.; Lee, B. W.; Gilman, R.; Sarty, A. J.; Strauch, S.; Higinbotham, D. W.; Piasetzky, E.; Allada, K.; Armstrong, W.; et al

    2011-02-03

    We performed high precision measurements of induced and transferred recoil proton polarization in d(more » $$\\vec{γ}$$, $$\\vec{p}$$)n for photon energies of 277--357 MeV and θcm = 20 ° -- 120 °. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. Moreover, at the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used.« less

  5. Testing helicity-dependent γγ → γγ scattering in the region of MeV

    NASA Astrophysics Data System (ADS)

    Homma, K.; Matsuura, K.; Nakajima, K.

    2016-01-01

    Light-by-light scatterings contain rich information on photon coupling to virtual and real particle states. In the context of quantum electrodynamics (QED), photons can couple to a virtual e^+e^- pair. Photons may also couple to known resonance states in the context of quantum chromodyanmics and electroweak dynamics in higher energy domains and possibly couple to unknown resonance states beyond the standard model. The perturbative QED calculations manifestly predict a maximized cross section at the MeV scale; however, no example of exact real-photon-real-photon scattering has yet been observed. Hence, we propose direct measurement with the maximized cross section at the center-of-mass system energy of 1-2 MeV to establish a firm footing at the MeV scale. Given current state of the art high power lasers, helicity-dependent elastic scattering may be observed at a reasonable rate, if a photon-photon collider exploiting γ -rays generated by the inverse nonlinear Compton process with electrons delivered from laser-plasma accelerators (LPA) are properly designed. We show that such verification is feasible in a table-top scale collider, which may be an unprecedented breakthrough in particle accelerators for basic physics research in contrast to energy frontier colliders.

  6. Revised Pioneer 10 absolute electron intensities in the inner Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Van Allen, J. A.

    1977-01-01

    Improved techniques for the analysis of Pioneer 10 Jupiter encounter data are used to obtain significantly more reliable values for energetic electron (Ee less than 21 MeV) intensities within the inner magnetosphere. The revised absolute intensities of electrons in the energy range 0.06-21 MeV are less than previous estimates by factors as great as 10 for L not exceeding 6. Previously published intensities at greater radial distances for Ee less than 21 MeV and at all radial distances for Ee greater than 21 MeV are not affected by the revisions.

  7. Evidence for Temperature-Dependent Electron Band Dispersion in Pentacene

    SciTech Connect

    Koch,N.; Vollmer, A.; Salzmann, I.; Nickel, B.; Weiss, H.; Rabe, J.

    2006-01-01

    Evidence for temperature-dependent electron band dispersion in a pentacene thin film polymorph on graphite is provided by angle- and energy-dependent ultraviolet photoelectron spectroscopy. The bands derived from the highest occupied molecular orbital exhibit dispersion of {approx}190 meV at room temperature, and {approx}240 meV at 120 K. Intermolecular electronic coupling in pentacene thin films is thus confirmed to be dependent on temperature and possibly crystal structure, as suggested by additional infrared absorption measurements.

  8. First Light: MeV Astrophysics from the Moon

    NASA Astrophysics Data System (ADS)

    Miller, Richard S.; Lawrence, David J.

    2016-06-01

    We report evidence of the first astrophysical source detected from the Moon at MeV energies. Our detection of Cygnus X-1 is a validation of a new investigative paradigm in which the lunar environment is intrinsic to the detection approach: the Lunar Occultation Technique (LOT). NASA’s Lunar Prospector mission served as a proxy for a dedicated LOT-based mission. The characteristic signature of temporal modulation, generated by repeated lunar occultations and encoded within acquired gamma-ray data (0.5–9 MeV), is consistent with an unambiguous detection of Cygnus X-1 at 5.4σ significance. Source localization and long-term monitoring capabilities of the LOT are also demonstrated. This “first light” detection verifies the basic tenets of the LOT methodology, reinforces its feasibility as an alternative astronomical detection paradigm for nuclear astrophysics investigations, and is an illustration of the fundamental benefits of the Moon as a platform for science.

  9. MeV Dark Matter and Small Scale Structure

    SciTech Connect

    Hooper, Dan; Kaplinghat, Manoj; Strigari, Louis E.; Zurek, Kathryn M.; /Wisconsin U., Madison

    2007-04-01

    WIMPs with electroweak scale masses (neutralinos, etc.) remain in kinetic equilibrium with other particle species until temperatures approximately in the range of 10 MeV to 1 GeV, leading to the formation of dark matter substructure with masses as small as 10{sup -4} M{sub {circle_dot}} to 10{sup -12} M{sub {circle_dot}}. However, if dark matter consists of particles with MeV scale masses, as motivated by the observation of 511 keV emission from the Galactic Bulge, such particles are naturally expected to remain in kinetic equilibrium with the cosmic neutrino background until considerably later times. This would lead to a strong suppression of small scale structure with masses below about 10{sup 7}M{sub {circle_dot}} to 10{sup 4} M{sub {circle_dot}}. This cutoff scale has important implications for present and future searches for faint Local Group satellite galaxies and for the missing satellites problem.

  10. Upgrading the Linac 400 MeV Switchyard

    SciTech Connect

    Charles M Ankenbrandt et al.

    2004-06-09

    This note describes changes in the 400 MeV beam transfer system from the Linac to improve the quality of the beam delivered to the Booster and to add the capability to direct beam to the MuCool Test Area (MTA). The new configuration has two pairs of pulsed dipole magnets on each side of the 400 MeV electrostatic Chopper. The smaller pair deflects vertically to replace the kick of the Chopper to send the beam to the Booster while the larger pair deflects horizontally to transfer the beam to the MTA. In this new scheme, the Chopper is uncharged while the beam is injected into the Booster such that the injection position does not rely on Chopper power supply regulation as it does now. A feature of the proposed upgrade is that no changes in the lattice functions are required in the lines to the Booster or to the Dump; once the four new magnets are installed, the switch between the old and new operating modes can be done from upstairs. The transfer to the MTA is already described in a previous note.

  11. Tracking and imaging gamma-ray experiment (TIGRE) for 300-keV to 100-MeV gamma-ray astronomy

    NASA Astrophysics Data System (ADS)

    Tumer, Tumay O.; Bhattacharya, Dipen; Blair, Scott C.; Case, Gary; Dixon, David D.; Liu, Chia-Ling; O'Neill, Terrence J.; White, R. Stephen; Zych, Allen D.

    1994-09-01

    The Tracking and Imaging Gamma-Ray Experiment (TIGRE) uses multilayers of silicon strip detectors both as a gamma-ray converter and to track Compton recoil electrons and positron-electron pairs. The silicon strip detectors also measure the energy losses of these particles. For Compton events, the direction and energy of the Compton scattered gamma ray are measured with arrays of small CsI(TI)-photodiode detectors so that an unique direction and energy can be found for each incident gamma ray. The incident photon direction for pair events is found from the initial pair particle directions. TIGRE is the first Compton telescope with a direct imaging capability. With a large (pi) -steradian field-of-view, it is sensitive to gamma rays from 0.3 to 100 MeV with a typical energy resolution of 3% (FWHM) and a 1-(sigma) angular resolution of 40 arc-minutes at 2 MeV. A small balloon prototype instrument is being constructed that has a high absolute detection efficiency of 8% over the full energy range and a sensitivity of 10 milliCrabs for an exposure of 500,000 s. TIGRE's innovative design also uses the polarization dependence of the Klein-Nishina formula for gamma-ray source polarization measurements. The telescope will be described in detail and new results from measurements at 0.5 MeV and Monte Carlo calculations from 1 to 100 MeV will be presented.

  12. Long pulse acceleration of MeV class high power density negative H- ion beam for ITER

    NASA Astrophysics Data System (ADS)

    Umeda, N.; Kojima, A.; Kashiwagi, M.; Tobari, H.; Hiratsuka, J.; Watanabe, K.; Dairaku, M.; Yamanaka, H.; Hanada, M.

    2015-04-01

    R&D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H- ion beam acceleration up to 1 MeV with 200 A/m2 for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mm to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated as 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m2 of negative ion beam, whose energy density increases two orders of magnitude since 2011.

  13. Long pulse acceleration of MeV class high power density negative H{sup −} ion beam for ITER

    SciTech Connect

    Umeda, N. Kojima, A.; Kashiwagi, M.; Tobari, H.; Hiratsuka, J.; Watanabe, K.; Dairaku, M.; Yamanaka, H.; Hanada, M.

    2015-04-08

    R and D of high power density negative ion beam acceleration has been carried out at MeV test facility in JAEA to realize ITER neutral beam accelerator. The main target is H{sup −} ion beam acceleration up to 1 MeV with 200 A/m{sup 2} for 60 s whose pulse length is the present facility limit. For long pulse acceleration at high power density, new extraction grid (EXG) has been developed with high cooling capability, which electron suppression magnet is placed under cooling channel similar to ITER. In addition, aperture size of electron suppression grid (ESG) is enlarged from 14 mm to 16 mm to reduce direct interception on the ESG and emission of secondary electron which leads to high heat load on the upstream acceleration grid. By enlarging ESG aperture, beam current increased 10 % at high current beam and total acceleration grid heat load reduced from 13 % to 10 % of input power at long pulse beam. In addition, heat load by back stream positive ion into the EXG is measured for the first time and is estimated as 0.3 % of beam power, while heat load by back stream ion into the source chamber is estimated as 3.5 ~ 4.0 % of beam power. Beam acceleration up to 60 s which is the facility limit, has achieved at 683 keV, 100 A/m{sup 2} of negative ion beam, whose energy density increases two orders of magnitude since 2011.

  14. Thermoelectric Figures of Merit of Zn4Sb3 and Zrnisn-based Half-heusler Compounds Influenced by Mev Ion-beam Bombardments

    NASA Astrophysics Data System (ADS)

    Budak, S.; Guner, S.; Muntele, C. I.; Ila, D.

    Semiconducting β-Zn4Sb3 and ZrNiSn-based half-Heusler compound thin films with applications as thermoelectric (TE) materials were prepared using ion beam assisted deposition (IBAD). High-purity solid zinc (Zn) and antimony (Sb) were evaporated by electron beam to grow the β-Zn4Sb3 thin film while high-purity zirconium (Zr) powder and nickel (Ni) tin (Sn) powders were evaporated by electron beam to grow the ZrNiSn-based half-Heusler compound thin film. Rutherford backscattering spectrometry (RBS) was used to analyze the composition of the thin films. The grown thin films were subjected to 5 MeV Si ions bombardment for generation of nanostructures in the films. We measured the thermal conductivity, Seebeck coefficient, and electrical conductivity of these two systems before and after 5 MeV Si ions beam bombardment. The two material systems have been identified as promising TE materials for the application of thermal-to-electrical energy conversion, but the efficiency still limits their applications. The electronic energy deposited due to ionization in the track of MeV ion beam couldcause localized crystallization. The nanostructures produced by MeV ion beam can cause significant change in both the electrical and the thermal conductivity of thin films, thereby improving the efficiency. We used the 3ω-method (3rd harmonic) measurement system to measure the cross-plane thermal conductivity, the van der Pauw measurement system to measure the electrical conductivity, and the Seebeck-coefficient measurement system to measure the cross-plane Seebeck coefficient. The thermoelectric figures of merit of the two material systems were then derived by calculations using the measurement results. The MeV ion-beam bombardment was found to decrease the thermal conductivity of thin films and increase the efficiency of thermal-to-electrical energy conversion.

  15. Observations of solar flare photon energy spectra from 20 keV to 7 MeV

    NASA Technical Reports Server (NTRS)

    Yoshimori, M.; Watanabe, H.; Nitta, N.

    1985-01-01

    Solar flare photon energy spectra in the 20 keV to 7 MeV range are derived from the Apr. 1, Apr. 4, apr. 27 and May 13, 1981 flares. The flares were observed with a hard X-ray and a gamma-ray spectrometers on board the Hinotori satellite. The results show that the spectral shape varies from flare to flare and the spectra harden in energies above about 400 keV. Effects of nuclear line emission on the continuum and of higher energy electron bremsstrahlung are considered to explain the spectral hardening.

  16. Towards tabletop production of intense quasimonochromatic X-ray beams using small 2-20 MeV accelerators

    NASA Astrophysics Data System (ADS)

    Avakian, Robert O.; Ispirian, Karo A.

    2005-08-01

    The existing synchrotron radiation sources and the fourth generation x-ray sources, which are projected at SLAC, USA, and DESY, Germany, are very expensive. For this reason the search for the novel and cheaper sources using various types of radiation produced by 2-20 MeV electrons available at many hospitals, universities and firms in various countries is of great interest. A review of the physics, history, new theoretical and experimental results and of some applications is given with a purpose to consider the possibilities of construction of small tabletop sources of quasimonochromatic X-ray photon beams necessary for scientific, industrial, medicine and other applications.

  17. Experimental lens-sparing optimization in therapeutic orbital irradiation with electron beams.

    PubMed

    Dirican, B; Oysul, K; Beyzadeoglu, M; Surenkok, S; Pak, Y

    2004-01-01

    There has been a number of approaches in the literature for therapeutic malignant and benign orbital irradiation. All techniques intend to deliver a homogenous dose to the orbital and retroorbital target volume while sparing the lens of excessive dose. In this experimental lens-sparing study, 4 MeV and 12 MeV anterior electron irradiation has been used with cerrobend shielding circular blocks of varying diameter and thickness placed on a thin Mylar at the distal tip of the electron applicator to spare the lens. The first phase of the study in water phantom has been designed to determine the shield thickness and diameter constant for 4 MeV and 12 MeV electron beams. After optimizing the lens dose by water phantom, the second phase of our study has been designed to measure doses at lens and other specific localizations in randophantom under same conditions with 4 MeV and 12 MeV electron beams. By this technique lens accumulated 18.56% of prescribed dose and lateral aspects of the lens received 44.59% of the prescribed dose in 4 MeV electron irradiation, whereas this was 13.86% and 44.80%, respectively in 12 MeV electron irradiation. The technique used is found to be an extremely simple and effective technique allowing an easier setup with excellent dose distribution characteristics with lens sparing applicable to orbital irradiation practice. PMID:15640945

  18. Radiation Dose from Reentrant Electrons

    NASA Technical Reports Server (NTRS)

    Badhwar, G.D.; Cleghorn, T. E.; Watts, J.

    2003-01-01

    In estimating the crew exposures during an EVA, the contribution of reentrant electrons has always been neglected. Although the flux of these electrons is small compared to the flux of trapped electrons, their energy spectrum extends to several GeV compared to about 7 MeV for trapped electrons. This is also true of splash electrons. Using the measured reentrant electron energy spectra, it is shown that the dose contribution of these electrons to the blood forming organs (BFO) is more than 10 times greater than that from the trapped electrons. The calculations also show that the dose-depth response is a very slowly changing function of depth, and thus adding reasonable amounts of additional shielding would not significantly lower the dose to BFO.

  19. A Monte Carlo comparison of PGNAA system performance using 252Cf neutrons, 2.8-MeV neutrons and 14-MeV neutrons

    NASA Astrophysics Data System (ADS)

    Naqvi, A. A.

    2003-10-01

    Monte Carlo simulations were carried out to compare performance of a 252Cf neutron and a 14-MeV neutron-based prompt γ-ray neutron activation analysis (PGNAA) system with that of the 2.8-MeV neutron-based PGNAA system at King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia. Since the energy of neutron beam used in the KFUPM PGNAA system is very close to that produced by a DD neutron generator, performance comparison between a DD and a DT neutron generator-based PGNAA system is highly desired. For the sake of comparison, the calculations were carried out for the PGNAA system with geometry similar to the KFUPM PGNAA system. These calculations were required to determine improvement in performance of the KFUPM PGNAA system if its 2.8-MeV neutron source is replaced by a 252Cf neutron source or a 14-MeV neutron source. Results of the calculations revealed that the geometry of the 252Cf neutron and the 2.8-MeV neutron-based PGNAA system are not significantly different but the geometry of the 14-MeV neutron-based system is significantly different from that of the 2.8-MeV neutron-based PGNAA system. Accordingly, the prompt γ-ray yields from the 252Cf neutron and the 2.8-MeV neutron-based PGNAA system is comparable but prompt γ-ray yields from 14-MeV neutron-based PGNAA system are about three times smaller than that from the 2.8-MeV neutron-based PGNAA system. This study has shown that performance of the 252Cf neutron-based PGNAA system is comparable with that of the 2.8-MeV neutron-based PGNAA system but the performance of the 14-MeV neutron-based PGNAA system is poorer than that of the 2.8-MeV neutron-based PGNAA system.

  20. Photoneutron source based on a compact 10 MeV betatron

    SciTech Connect

    Bell, Z.W.; Chaklov, V.L.; Golovkov, V.M.

    1998-05-08

    Accelerator-based photoneutron sources have enjoyed wide use and offer the advantages of long term stability, ease of control and absence of radioactive materials. The authors report here measurements of the yield of photoneutrons from a neutron generator using a compact betatron (466 kg total weight, 900 by 560 by 350 mm betatron dimensions) at the Institute of Introscopy of the Tomsk Polytechnic University. Electrons were accelerated to energies up to 10 MeV and produced a bremsstrahlung beam with a dose rate of 0.16 Gy/min (at 10 MeV, 1 meter from the bremsstrahlung target) to irradiate LiD, Be, depleted U, and Pb neutron-producing targets. The angular distributions of photoneutrons produced by bremsstrahlung beams were measured with a long counter and integrated to determine neutron yield. In addition, neutron time of flight spectra were recorded from all targets using a 15 meter flight path perpendicular to the photon beam. The maximum observed yields were 5.2 {times} 10{sup 4} n/rad/gram target obtained with LiD, 1.7 {times} 10{sup 4} n/rad/gram from Be, 3.3 {times} 10{sup 3} n/rad/gram from U, and 7.5 {times} 10{sup 2} n/rad/gram from Pb. Optimization of target dimensions, shape, and positioning is expected to increase the yield from the LiD target by a factor of 35. With the increased yield, this compact betatron-based system could find application in the interrogation of waste containers for fissile material.

  1. Utilization of new 150-MeV neutron and proton evaluations in MCNP

    SciTech Connect

    Little, R.C.; Frankle, S.C.; Hughes, H.G. III; Prael, R.E.

    1997-10-01

    MCNP{trademark} and LAHET{trademark} are two of the codes included in the LARAMIE (Los Alamos Radiation Modeling Interactive Environment) code system. Both MCNP and LAHET are three-dimensional continuous-energy Monte Carlo radiation transport codes. The capabilities of MCNP and LAHET are currently being merged into one code for the Accelerator Production of Tritium (APT) program at Los Alamos National Laboratory. Concurrently, a significant effort is underway to improve the accuracy of the physics in the merged code. In particular, full nuclear-data evaluations (in ENDF6 format) for many materials of importance to APT are being produced for incident neutrons and protons up to an energy of 150-MeV. After processing, cross-section tables based on these new evaluations will be available for use fin the merged code. In order to utilize these new cross-section tables, significant enhancements are required for the merged code. Neutron cross-section tables for MCNP currently specify emission data for neutrons and photons only; the new evaluations also include complete neutron-induced data for protons, deuterons, tritons, and alphas. In addition, no provision in either MCNP or LAHET currently exists for the use of incident charged-particle tables other than for electrons. To accommodate the new neutron-induced data, it was first necessary to expand the format definition of an MCNP neutron cross-section table. The authors have prepared a 150-MeV neutron cross-section library in this expanded format for 15 nuclides. Modifications to MCNP have been implemented so that this expanded neutron library can be utilized.

  2. MEIC electron cooling program

    SciTech Connect

    Derbenev, Yaroslav S.; Zhang, Yuhong

    2014-12-01

    Cooling of proton and ion beams is essential for achieving high luminosities (up to above 1034 cm-2s-1) for MEIC, a Medium energy Electron-Ion Collider envisioned at JLab [1] for advanced nuclear science research. In the present conceptual design, we utilize the conventional election cooling method and adopted a multi-staged cooling scheme for reduction of and maintaining low beam emittances [2,3,4]. Two electron cooling facilities are required to support the scheme: one is a low energy (up to 2 MeV) DC cooler installed in the MEIC ion pre-booster (with the proton kinetic energy up to 3 GeV); the other is a high electron energy (up to 55 MeV) cooler in the collider ring (with the proton kinetic energy from 25 to 100 GeV). The high energy cooler, which is based on the ERL technology and a circulator ring, utilizes a bunched electron beam to cool bunched proton or ion beams. To complete the MEIC cooling concept and a technical design of the ERL cooler as well as to develop supporting technologies, an R&D program has been initiated at Jefferson Lab and significant progresses have been made since then. In this study, we present a brief description of the cooler design and a summary of the progress in this cooling R&D.

  3. MEIC electron cooling program

    DOE PAGESBeta

    Derbenev, Yaroslav S.; Zhang, Yuhong

    2014-12-01

    Cooling of proton and ion beams is essential for achieving high luminosities (up to above 1034 cm-2s-1) for MEIC, a Medium energy Electron-Ion Collider envisioned at JLab [1] for advanced nuclear science research. In the present conceptual design, we utilize the conventional election cooling method and adopted a multi-staged cooling scheme for reduction of and maintaining low beam emittances [2,3,4]. Two electron cooling facilities are required to support the scheme: one is a low energy (up to 2 MeV) DC cooler installed in the MEIC ion pre-booster (with the proton kinetic energy up to 3 GeV); the other is amore » high electron energy (up to 55 MeV) cooler in the collider ring (with the proton kinetic energy from 25 to 100 GeV). The high energy cooler, which is based on the ERL technology and a circulator ring, utilizes a bunched electron beam to cool bunched proton or ion beams. To complete the MEIC cooling concept and a technical design of the ERL cooler as well as to develop supporting technologies, an R&D program has been initiated at Jefferson Lab and significant progresses have been made since then. In this study, we present a brief description of the cooler design and a summary of the progress in this cooling R&D.« less

  4. Proton Polarimeter Calibration between 82 and 217 MeV

    SciTech Connect

    Glister, J; Lee, B; Beck, A; Brash, E; Camsonne, A; Choi, S; Dumas, J; Feuerbach, R; Gilman, R; Higinbotham, D W; Jiang, X; Jones, M K; May-Tal Beck, S; McCullough, E; Paolone, M; Piasetzky, E; Roche, J; Rousseau, Y; Sarty, A J; Sawatzky, B; Strauch, S

    2009-07-01

    The proton analyzing power in carbon has been measured for energies of 82 to 217 MeV and proton scattering angles of 5 to 41 degrees. The measurements were carried out using polarized protons from the elastic scattering H(pol. e, pol. p) reaction and the Focal Plane Polarimeter (FPP) in Hall A of Jefferson Lab. A new parameterization of the FPP p-C analyzing power was fit to the data, which is in good agreement with previous parameterizations and provides an extension to lower energies and larger angles. The main conclusions are that all polarimeters to date give consistent measurements of the carbon analyzing power, independently of the details of their construction and that measuring on a larger angular range significantly improves the polarimeter figure of merit at low energies.

  5. Little Boy neutron spectrum below 3 MeV

    SciTech Connect

    Evans, A.E.; Bennett, E.F.; Yule, T.J.

    1984-01-01

    The leakage neutron spectrum from the Little Boy replica has been measured from 12 keV to 3 MeV using a high-resolution /sup 3/He ionization chamber, and from 1 keV to 3 MeV using proton-recoil proportional counters. The /sup 3/He-spectrometer measurements were made at distances of 0.75 and 2.0 m from the active center and at angles of 0/sup 0/, 45/sup 0/, and 90/sup 0/ with respect to the axis of the assembly. Proton-recoil measurments were made at 90/sup 0/ to the assembly axis at distances of 0.75 and 2.0 m, with a shielded measurement made at 2.0 m to estimate background due to scattering. The /sup 3/He spectrometer was calibrated at Los Alamos using monoenergetic /sup 7/Li(p,n)/sup 7/Be neutrons to generate a family of response functions. The proton-recoil counters were calibrated at Argonne by studying the capture of thermal neutrons by nitrogen in the counters, by observation of the 24-keV neutron resonance in iron, and by relating to the known hydrogen content of the counters. The neutron spectrum from Little Boy was found to be highly structured, with peaks corresponding to minima in the iron total neutron cross section. In particular, influence of the 24-keV iron window was evident in both sets of spectra. The measurements provide information for dosimetry calculations and also a valuable intercomparison of neutron spectrometry using the two different detector types. Spectra measured with both detectors are in essential agreement. 8 references, 7 figures, 2 tables.

  6. Parity Violation in Proton-Proton Scattering at 47 Mev.

    NASA Astrophysics Data System (ADS)

    Tanner, Danelle Mary

    A measurement of parity-violation in proton-proton scattering at 47 MeV has been completed by observing the longitudinal analyzing power. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). where (sigma)('+)((sigma)('-)) is the scattering cross section for positive (negative) helicity. Polarized protons from an atomic beam ion source were accelerated by the 224-cm Texas A&M University cyclotron to an energy of 50 MeV, producing a vertically polarized beam. A superconducting solenoid magnet precessed the beam polarization into the horizontal plane after which a 47.6(DEGREES) bending magnet precessed the polarization into the longtitudinal direction (p(,z) = 0.69 (+OR-) 0.02). RF transitions reversed the polarization direction every 21 msec. Protons scattered from the high pressure ((DBLTURN)37 atm), 42-cm long H(,2) gas target were detected by four plastic scintillators located in the target chamber. Photomultiplier tubes amplified the light from the scintillators, providing a signal proportional to the scattered beam intensity. A lock-in amplifier (LIA) synchronized to the spin-flip frequency compared the scattered intensity to the total beam intensity, measured with a Faraday cup. The output of the LIA was integrated for one second and then read by an ADC. Polarimeters were used to monitor both beam intensity and polarization profiles. A series of tests were performed to determine the role of spurious asymmetries due to changes in beam position and angle, and due to beam intensity modulations correlated with the spin reversal. The result after correction for beam intensity modulation was A(,z) = -(4.6 (+OR-) 2.6) x 10('-7). A more conservative result, taking into account all of the possible spurious asymmetries was A(,z) = -(4.6 (+OR-) 4.2) x 10('-7).

  7. Shielding measurements for a 230 MeV proton beam

    SciTech Connect

    Siebers, J.V.

    1990-01-01

    Energetic secondary neutrons produced as protons interact with accelerator components and patients dominate the radiation shielding environment for proton radiotherapy facilities. Due to the scarcity of data describing neutron production, attenuation, absorbed dose, and dose equivalent values, these parameters were measured for 230 MeV proton bombardment of stopping length Al, Fe, and Pb targets at emission angles of 0{degree}, 22{degree}, 45{degree}, and 90{degree} in a thick concrete shield. Low pressure tissue-equivalent proportional counters with volumes ranging from 1 cm{sup 3} to 1000 cm{sup 3} were used to obtain microdosimetric spectra from which absorbed dose and radiation quality are deduced. Does equivalent values and attenuation lengths determined at depth in the shield were found to vary sharply with angle, but were found to be independent of target material. Neutron dose and radiation length values are compared with Monte Carlo neutron transport calculations performed using the Los Alamos High Energy Transport Code (LAHET). Calculations used 230 MeV protons incident upon an Fe target in a shielding geometry similar to that used in the experiment. LAHET calculations overestimated measured attenuation values at 0{degree}, 22{degree}, and 45{degree}, yet correctly predicted the attenuation length at 90{degree}. Comparison of the mean radiation quality estimated with the Monte Carlo calculations with measurements suggest that neutron quality factors should be increased by a factor of 1.4. These results are useful for the shielding design of new facilities as well as for testing neutron production and transport calculations.

  8. Inelastic Scattering Of Electrons By Protons

    DOE R&D Accomplishments Database

    Cone, A. A.; Chen, K. W.; Dunning, J. R. Jr.; Hartwig, G.; Ramsey, N. F.; Walker, J. K.; Wilson, R.

    1966-12-01

    The inelastic scattering of electrons by protons has been measured at incident electron energies up to 5 BeV/c and momentum transfers q{sup 2}=4(BeV/c){sup 2}. Excitation of known nucleon resonances at M=1238, 1512, 1688 and possibly 1920 MeV have been observed. The calculations for the resonance at M=1238 MeV have been compared with calculations by Adler based on the dispersion theory of Chew, Goldberger, Low and Nambu. The agreement is good. Qualitative models are discussed for the other resonances.

  9. Radiological safety of medical devices sterilized with X-rays at 7.5 MeV

    NASA Astrophysics Data System (ADS)

    Grégoire, O.; Cleland, M. R.; Mittendorfer, J.; Vander Donckt, M.; Meissner, J.

    2003-06-01

    The induced radioactivity in medical devices when sterilized with 7.5 MeV X-rays has been investigated theoretically and verified by dedicated experiments. The experimental setup has been chosen to simulate closely the situation in a commercial irradiation facility. The purpose of this study is twofold: compare activation of medical devices with regulatory limits and evaluate corresponding dose exposure of persons in contact with those devices. Samples of medical devices, classified in several test groups, were located in a stack of low-density material at the position of the highest photoneutron fluence and irradiated to X-ray doses between 25 and 30 kGy. The induced activities were measured with high purity germanium (HPGe) gamma ray spectrometers. The X-rays were generated in a tantalum target using a 7.3 MeV electron beam with a narrow energy spread during the first experiment and with a broad energy spectrum for a second one. Results have been scaled to 50 kGy and compared with theoretical estimates. In addition, the radiation exposure of four categories of persons (logistics personnel in the irradiation facility, truck drivers, doctors and patients) has been calculated from the measured activities. The measured activities are higher than theoretical expectations but still below governmental regulations. The annual dose received by the person category with the highest exposure is about 1% of the worldwide average environmental exposure, and for other categories it is negligible. The paper concludes that provided some precautions are considered, sterilization with X-rays from 7.5 MeV electrons can be regarded safe from the standpoint of public health and personal safety.

  10. Optimum target source term estimation for high energy electron accelerators

    NASA Astrophysics Data System (ADS)

    Nayak, M. K.; Sahu, T. K.; Nair, Haridas G.; Nandedkar, R. V.; Bandyopadhyay, Tapas; Tripathi, R. M.; Hannurkar, P. R.

    2016-05-01

    Optimum target for bremsstrahlung emission is defined as the thickness of the target material, which produces maximum bremsstrahlung yield, on interaction of electron with the target. The bremsstrahlung dose rate per unit electron beam power at a distance of 1 m from the target material gives the optimum target source term. In the present work, simulations were performed for three different electron energies, 450, 1000 and 2500 MeV using EGSnrc Monte-Carlo code to determine the optimum thickness. An empirical relation for optimum target as a function of electron energy and atomic number of the target materials is found out from results. Using the simulated optimum target thickness, experiments are conducted to determine the optimum target source term. For the experimental determination, two available electron energies, 450 MeV and 550 MeV from booster synchrotron of Indus facility is used. The optimum target source term for these two energies are also simulated. The experimental and simulated source term are found to be in very good agreement within ±3%. Based on the agreement of the simulated source term with the experimental source term at 450 MeV and 550 MeV, the same simulation methodology is used to simulate optimum target source term up to 2500 MeV. The paper describes the simulations and experiments carried out on optimum target bremsstrahlung source term and the results obtained.

  11. L- and M-shell x-ray production cross sections of Nd, Gd, Ho, Yb, Au, and Pb by 25-MeV carbon and 32-MeV oxygen ions

    SciTech Connect

    Andrews, M.C.; McDaniel, F.D.; Duggan, J.L.; Miller, P.D.; Pepmiller, P.L.; Krause, H.F.; Rosseel, T.M.; Rayburn, L.A.; Mehta, R.; Lapicki, G.; and others

    1987-10-15

    L- and M-shell x-ray production cross sections have been measured for thin solid targets of neodymium, gadolinium, holmium, ytterbium, gold, and lead by 25-MeV /sub //sub <1/ /sub 6//sup 2/C/sup q//sup +/ (q = 4,5,6) and by 32-MeV /sub //sub <1/ /sub 8//sup 6/O/sup q//sup +/ (q = 5,7,8). The cross sections were determined from measurements made with thin targets (less than 2.25 ..mu..g/cm/sup 2/). For projectiles with one or two K-shell vacancies, the target x-ray production cross sections were found to be enhanced over those for projectiles without a K-shell vacancy. The sum of direct ionization to the continuum (DI) plus electron capture (EC) to the L,M,N,. . . shells and EC to the K shell of the projectile have been extracted from the data. The results are compared to the predictions of first Born theories, i.e., plane-wave Born approximation for DI and Oppenheimer-Brinkman-Kramers formula of Nikolaev for EC, and to the ECPSSR that accounts for energy loss and Coulomb deflection of the projectile as well as for relativistic and perturbed stationary states of inner-shell electrons.

  12. L- and M-shell x-ray production cross sections of neodymium, gadolinium, holmium, ytterbium, gold, and lead by 25-MeV carbon and 32-MeV oxygen ions

    SciTech Connect

    Andrews, M.C. III

    1987-01-01

    L- and M-shell x-ray production cross sections were measured for thin solid targets of neodymium, gadolinium, holmium, ytterbium, gold, and lead by 25-MeV /sup 12/C/sup q+/ (q = 4,5,6) and by 32-MeV /sup 16/O/sup q+/ (q = 5,7,8). The cross sections were determined from measurements made with thin targets (<2.5 ..mu..g/cm/sup 2/). For projectiles with one or two K-shell vacancies, the target x-ray production cross sections were found to be enhanced over those for projectiles without a K-shell vacancy. The sum of direct ionization to the continuum (DI) plus electron capture (EC) to the L, M, N... shells and EC to the K shell of the projectile were extracted from the data. The results are compared to the predictions of first Born theories, i.e., plane-wave Born approximation for DI and Oppenheimer-Brinkman-Kramers formula of Nikolaev for EC and to the ECPSSR approach that accounts for energy loss and Coulomb deflection of the projectile as well as for relativistic and perturbed stationary states of inner-shell electrons.

  13. L- and M-shell x-ray production cross sections of Nd, Gd, Ho, Yb, Au, and Pb by 25-MeV carbon and 32-MeV oxygen ions

    NASA Astrophysics Data System (ADS)

    Andrews, M. C.; McDaniel, F. D.; Duggan, J. L.; Miller, P. D.; Pepmiller, P. L.; Krause, H. F.; Rosseel, T. M.; Rayburn, L. A.; Mehta, R.; Lapicki, G.

    1987-10-01

    L- and M-shell x-ray production cross sections have been measured for thin solid targets of neodymium, gadolinium, holmium, ytterbium, gold, and lead by 25-MeV 1 26Cq+ (q=4,5,6) and by 32-MeV 1 68Oq+ (q=5,7,8). The cross sections were determined from measurements made with thin targets (less than 2.25 μg/cm2). For projectiles with one or two K-shell vacancies, the target x-ray production cross sections were found to be enhanced over those for projectiles without a K-shell vacancy. The sum of direct ionization to the continuum (DI) plus electron capture (EC) to the L,M,N,. . . shells and EC to the K shell of the projectile have been extracted from the data. The results are compared to the predictions of first Born theories, i.e., plane-wave Born approximation for DI and Oppenheimer-Brinkman-Kramers formula of Nikolaev for EC, and to the ECPSSR that accounts for energy loss and Coulomb deflection of the projectile as well as for relativistic and perturbed stationary states of inner-shell electrons.

  14. L and M-Shell X-Ray Production Cross-Sections of Neodymium, Gadolinium, Holmium, Ytterbium, Gold, and Lead by 25-MEV Carbon and 32-MEV Oxygen Ions.

    NASA Astrophysics Data System (ADS)

    Andrews, Mike C.(Io), III

    1987-12-01

    L- and M-shell x-ray production cross sections have been measured for thin solid targets of neodymium, gadolinium, holmium, ytterbium, gold, and lead by 25 MeV _sp{6}{12}C ^{rm q+} (q = 4,5,6) and by 32 MeV _sp{8}{16} O^{rm q+} (q = 5,7,8). The cross sections were determined from measurements made with thin targets (<2.5 mu g/cm2). For projectiles with one or two K-shell vacancies, the target x-ray production cross sections were found to be enhanced over those for projectiles without a K-shell vacancy. The sum of direct ionization to the continuum (DI) plus electron capture (EC) to the L, M, Nldots shells and EC to the K-shell of the projectile have been extracted from the data. The results are compared to the predictions of first Born theories, i.e., plane wave Born approximation for DI and Oppenheimer -Brinkman-Kramers formula of Nikolaev for EC and to the ECPSSR approach that accounts for Energy loss and Coulomb deflection of the projectile as well as for Relativistic and Perturbed Stationary States of inner shell electrons.

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

    SciTech Connect

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

    2012-09-15

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

  16. FLUKA and PENELOPE simulations of 10 keV to 10 MeV photons in LYSO and soft tissue

    NASA Astrophysics Data System (ADS)

    Chin, M. P. W.; Böhlen, T. T.; Fassò, A.; Ferrari, A.; Ortega, P. G.; Sala, P. R.

    2014-02-01

    Monte Carlo simulations of electromagnetic particle interactions and transport by FLUKA and PENELOPE were compared. 10 keV to 10 MeV incident photon beams impinged a LYSO crystal and a soft-tissue phantom. Central-axis as well as off-axis depth doses agreed within 1 s.d.; no systematic under- or over-estimate of the pulse height spectra was observed from 100 keV to 10 MeV for both materials, agreement was within 5%. Simulation of photon and electron transport and interactions at this level of precision and reliability is of significant impact, for instance, on treatment monitoring of hadrontherapy where a code like FLUKA is needed to simulate the full suite of particles and interactions (not just electromagnetic). At the interaction-by-interaction level, apart from known differences in condensed history techniques, two-quanta positron annihilation at rest was found to differ between the two codes. PENELOPE produced a 511 keV sharp line, whereas FLUKA produced visible acolinearity, a feature recently implemented to account for the momentum of shell electrons.

  17. A comparative study of 30MeV boron{sup 4+} and 60MeV oxygen{sup 8+} ion irradiated Si NPN BJTs

    SciTech Connect

    Kumar, M. Vinay Krishnaveni, S.; Yashoda, T.; Dinesh, C. M.; Krishnakumar, K. S.; Jayashree, B.; Ramani

    2015-06-24

    The impact of 30MeV boron{sup 4+} and 60MeV oxygen{sup 8+} ion irradiation on electrical characteristics of 2N3773 Si NPN Bipolar junction transistors (BJTs) is reported in the present study. The transistors were decapped and irradiated at room temperature. Gummel characteristics, DC current gain and Capacitance-voltage (C-V) characteristics were studied before and after irradiation at different fluences. DC current gain has decreased significantly in both boron and oxygen ion irradiation. Also the value of capacitance decreased 3-4 times with increase in fluence. Both 30MeV boron ion and 60MeV oxygen ion induced similar extent of degradation in electrical characteristics of the transistor.

  18. Production of the {omega} meson in the pd{yields}{sup 3}He{omega} reaction at 1450 MeV and 1360 MeV

    SciTech Connect

    Schoenning, K.; Calen, H.; Fransson, K.; Gustafsson, L.; Hoeistad, B.; Jacewicz, M.; Johansson, T.; Keleta, S.; Kullander, S.; Kupsc, A.; Marciniewski, P.; Petren, H.; Ruber, R. J. M. Y.; Engblom, P. Thoerngren; Zlomanczuk, J.; Bargholtz, Chr.; Geren, L.; Lindberg, K.; Tegner, P.-E.; Zartova, I.

    2009-04-15

    The production of {omega} mesons in the pd{yields}{sup 3}He{omega} reaction has been studied at two energies near the kinematic threshold, T{sub p}=1450 MeV and T{sub p}=1360 MeV. The differential cross section was measured as a function of the {omega} c.m. angle at both energies over the whole angular range. Whereas the results at 1360 MeV are consistent with isotropy, strong rises are observed near both the forward and backward directions at 1450 MeV. Calculations made using a two-step model with an intermediate pion fail to reproduce the shapes of the measured angular distributions and also underestimate the total cross sections.

  19. Surface conduction of topological Dirac electrons in bulk insulating Bi2Se3

    NASA Astrophysics Data System (ADS)

    Fuhrer, Michael

    2013-03-01

    The three dimensional strong topological insulator (STI) is a new phase of electronic matter which is distinct from ordinary insulators in that it supports on its surface a conducting two-dimensional surface state whose existence is guaranteed by topology. I will discuss experiments on the STI material Bi2Se3, which has a bulk bandgap of 300 meV, much greater than room temperature, and a single topological surface state with a massless Dirac dispersion. Field effect transistors consisting of thin (3-20 nm) Bi2Se3 are fabricated from mechanically exfoliated from single crystals, and electrochemical and/or chemical gating methods are used to move the Fermi energy into the bulk bandgap, revealing the ambipolar gapless nature of transport in the Bi2Se3 surface states. The minimum conductivity of the topological surface state is understood within the self-consistent theory of Dirac electrons in the presence of charged impurities. The intrinsic finite-temperature resistivity of the topological surface state due to electron-acoustic phonon scattering is measured to be ~60 times larger than that of graphene largely due to the smaller Fermi and sound velocities in Bi2Se3, which will have implications for topological electronic devices operating at room temperature. As samples are made thinner, coherent coupling of the top and bottom topological surfaces is observed through the magnitude of the weak anti-localization correction to the conductivity, and, in the thinnest Bi2Se3 samples (~ 3 nm), in thermally-activated conductivity reflecting the opening of a bandgap.

  20. Andromede project: Surface analysis and modification with probes from hydrogen to nano-particles in the MeV energy range

    NASA Astrophysics Data System (ADS)

    Eller, Michael J.; Cottereau, Evelyne; Rasser, Bernard; Verzeroli, Elodie; Agnus, Benoit; Gaubert, Gabriel; Donzel, Xavier; Delobbe, Anne; Della-Negra, Serge

    2015-12-01

    The Andromede project is the center of a multi-disciplinary team which will build a new instrument for surface modification and analysis using the impact of probes from hydrogen to nano-particles (Au400+4) in the MeV range. For this new instrument a series of atomic, polyatomic, molecular and nano-particle ion beams will be delivered using two ion sources in tandem, a liquid metal ion source and an electron cyclotron resonance source. The delivered ion beams will be accelerated to high energy with a 4 MeV van de Graaff type accelerator. By using a suite of probes in the MeV energy range, ion beam analysis techniques, MeV atomic and cluster secondary ion mass spectrometry can all be performed in one location. A key feature of the instrument is its ability to produce an intense beam for injection into the accelerator. The commissioning of the two sources shows that intense beams from atomic ions to nano-particles can be delivered for subsequent acceleration. The calculations and measurements for the two sources are presented.

  1. Predicting solar energetic proton events (E > 10 MeV)

    NASA Astrophysics Data System (ADS)

    NúñEz, Marlon

    2011-07-01

    A high level of proton radiation exposure can be dangerous to astronauts, satellite equipment, and air passengers/crew flying along polar routes. The presented solar energetic proton (SEP) event forecaster is based on a dual-model approach for predicting the time interval within which the integral proton flux is expected to meet or surpass the Space Weather Prediction Center threshold of J (E > 10 MeV) = 10 pr cm-2 sr-1 s-1 and the intensity of the first hours of well- and poorly connected SEP events. This forecaster analyzes flare and near-Earth space environment data (soft X-ray, differential and integral proton fluxes). The purpose of the first model is to identify precursors of well-connected events by empirically estimating the magnetic connectivity from the associated CME/flare process zone to the near-Earth environment and identifying the flare temporally associated with the phenomenon. The goal of the second model is to identify precursors of poorly connected events by using a regression model that checks whether the differential proton flux behavior is similar to that in the beginning phases of previous historically poorly connected SEP events and thus deduce similar consequences. An additional module applies a higher-level analysis for inferring additional information about the situation by filtering out inconsistent preliminary forecasts and estimating the intensity of the first hours of the predicted SEP events. The high-level module periodically retrieves solar data and, in the case of well-connected events, automatically identifies the associated flare and active region. For the events of solar cycles 22 and 23 of the NOAA/SWPC SEP list, the presented dual-model system, called UMASEP, has a probability of detection of all well- and poorly connected events of 80.72% (134/166) and a false alarm rate of 33.99% (69/203), which outperforms current automatic forecasters in predicting >10 MeV SEP events. The presented forecaster has an average warning time

  2. MeV Au Ion Irradiation in Silicon and Nanocrystalline Zirconia Film Deposited on Silicon Substrate

    SciTech Connect

    Chang, Yongqin; Zhang, Yanwen; Zhu, Zihua; Edmondson, Philip D.; Weber, William J.

    2012-09-01

    Nanocrystalline zirconia (ZrO2) film with thickness of 305 nm deposited on a silicon substrate was irradiated with 2 MeV Au ions to different fluences at different temperatures. The implanted ion profiles were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and simulated using the stopping and range of ions inmatter (SRIM) code, respectively. The experimental results show that a large fraction of the incident Au ions penetrates through the ZrO2 film and are deposited into the Si substrate. At the interface of ZrO2 and Si, a sudden decrease of Au concentration is observed due to the much larger scattering cross section of Au in ZrO2 than in Si. The depth profile of the Au ions is measured in both the ZrO2 films and the Si substrates, and the results show that the Au distribution profiles do not exhibit a dependence on irradiation temperature. The local Au concentration increases proportionally with the irradiation fluence, suggesting that no thermal or irradiation-induced redistribution of the implanted Au ions. However, the Au concentration in the ZrO2 films, as determined by SIMS, is considerably lower than that predicted by the SRIM results, and the penetration depth from the SIMS measurements is much deeper than that from the SRIM predictions. These observations can be explained by an overestimation of the electronic stopping power, used in the SRIM program, for heavy incident ions in light targets. Over-estimation of the heavy-ion electronic stopping power may lead to errors in local dose calculation and underestimation of the projected range of slow heavy ions in targets that contain light elements. A quick estimate based on a reduced target density may be used to compensate the overestimation of the electronic stopping power in the SRIM program to provide better ion profile prediction.

  3. Dose distribution under external eye shields for high energy electrons

    SciTech Connect

    Rustgi, S.N.

    1986-01-01

    Effectiveness of eye shields in reducing the dose to the eye lens from 6 and 9 MeV electron beams from a linear accelerator has been evaluated. The thickness of the shields made from cerrobend was such that only bremsstrahlung photons were transmitted. A shield with a diameter of 1.3 cm and thickness of 1 cm was adequate for the 9 MeV electron beam. The optimum shield to phantom surface distance was 1 cm or less. The same shield with a thickness of 0.5 cm was found to be ineffective with a 6 MeV electron beam. The dose under the shield is greater than predicted by transmission measurements because of the contribution of phantom and electron cone generated scattered electrons.

  4. Towards demonstration of electron cooling with bunched electron beam

    SciTech Connect

    Fedotov, A.

    2012-01-11

    All electron cooling systems which were in operation so far employed electron beam generated with an electrostatic electron gun in DC operating mode, immersed in a longitudinal magnetic field. At low energies magnetic field is also being used to transport electron beam through the cooling section from the gun to the collector. At higher energies (few MeV), it was shown that one can have simpler electron beam transport without continuous magnetic field. Because of a rather weak magnetic field on the cathode and in the cooling section the latter approach was referred to as 'non-magnetized cooling', since there was no suppression of the transverse angular spread of the electron beam with the magnetic field in the cooling section. Such a cooler successfully operated at FNAL (2005-11) at electron beam energy of 4.3 MeV. Providing cooling at even higher energies would be easier with RF acceleration of electron beam, and thus using bunched electron beam for cooling. Significant efforts were devoted to explore various aspects of such bunched electron beam cooling as part of R and D of high-energy electron cooling for RHIC. However, experimental studies of such cooling are still lacking. Establishing this technique experimentally would be extremely useful for future high-energy applications. Presently there is an ongoing effort to build Proof-of-Principle (PoP) experiment of Coherent Electron Cooling (CEC) at RHIC, which promises to be superior to conventional electron cooling for high energies. Since the CEC experiment is based on bunched electron beam and it has sections where electron beam co-propagates with the ion beam at the same velocity, it also provides a unique opportunity to explore experimentally conventional electron cooling but for the first time with a bunched electron beam. As a result, it allows us to explore techniques needed for the high-energy electron cooling such as 'painting' with a short electron beam and control of ion beam distribution under

  5. Synthesis of BaTiO[subscript 3]-20wt%CoFe[subscript 2]O[subscript 4] Nanocomposites via Spark Plasma Sintering

    SciTech Connect

    Ghosh, Dipankar; Han, Hyuksu; Nino, Juan C.; Subhash, Ghatu; Jones, Jacob L.

    2012-10-23

    Barium titanate-20wt% cobalt ferrite (BaTiO{sub 3}-20wt%CoFe{sub 2}O{sub 4}) nanocomposites were sintered from nanocrystalline BaTiO{sub 3} and CoFe{sub 2}O{sub 4} powders using spark plasma sintering (SPS) and pressureless sintering (PS) techniques. Using SPS, dense polycrystalline composites were obtained at a sintering temperature as low as 860 C and a time of 5 min whereas PS required a higher sintering temperature (1150 C) and time (120 min) to obtain similarly dense composites. Microstructural analysis of the composites showed that both the techniques retained nanocrystalline grain sizes after sintering. High resolution X-ray diffraction measurements revealed that the BaTiO{sub 3}-20wt%CoFe{sub 2}O{sub 4} composites sintered by the SPS technique did not exhibit formation of any new phase(s) due to reaction between the BaTiO{sub 3} and CoFe{sub 2}O{sub 4} phases during sintering. However, the PS technique resulted in the formation of additional phases (other than the BaTiO{sub 3} and CoFe{sub 2}O{sub 4} phases) in the composites. While the composites synthesized by SPS were of superior phase-purity, evidence of Fe diffusion from the spinel to the perovskite phase was found from X-ray diffraction and permittivity measurements.

  6. Effets des electrons secondaires sur l'ADN

    NASA Astrophysics Data System (ADS)

    Boudaiffa, Badia

    Les interactions des electrons de basse energie (EBE) representent un element important en sciences des radiations, particulierement, les sequences se produisant immediatement apres l'interaction de la radiation ionisante avec le milieu biologique. Il est bien connu que lorsque ces radiations deposent leur energie dans la cellule, elles produisent un grand nombre d'electrons secondaires (4 x 104/MeV), qui sont crees le long de la trace avec des energies cinetiques initiales bien inferieures a 20 eV. Cependant, il n'y a jamais eu de mesures directes demontrant l'interaction de ces electrons de tres basse energie avec l'ADN, du principalement aux difficultes experimentales imposees par la complexite du milieu biologique. Dans notre laboratoire, les dernieres annees ont ete consacrees a l'etude des phenomenes fondamentaux induits par impact des EBE sur differentes molecules simples (e.g., N2, CO, O2, H2O, NO, C2H 4, C6H6, C2H12) et quelques molecules complexes dans leur phase solide. D'autres travaux effectues recemment sur des bases de l'ADN et des oligonucleotides ont montre que les EBE produisent des bris moleculaires sur les biomolecules. Ces travaux nous ont permis d'elaborer des techniques pour mettre en evidence et comprendre les interactions fondamentales des EBE avec des molecules d'interet biologique, afin d'atteindre notre objectif majeur d'etudier l'effet direct de ces particules sur la molecule d'ADN. Les techniques de sciences des surfaces developpees et utilisees dans les etudes precitees peuvent etre etendues et combinees avec des methodes classiques de biologie pour etudier les dommages de l'ADN induits par l'impact des EBE. Nos experiences ont montre l'efficacite des electrons de 3--20 eV a induire des coupures simple et double brins dans l'ADN. Pour des energies inferieures a 15 eV, ces coupures sont induites par la localisation temporaire d'un electron sur une unite moleculaire de l'ADN, ce qui engendre la formation d'un ion negatif transitoire

  7. MERLIN - A meV Resolution Beamline at the ALS

    SciTech Connect

    Reininger, Ruben; Bozek, John; Chuang, Y.-D.; Howells, Malcolm; Kelez, Nicholas; Prestemon, Soren; Marks, Steve; Warwick, Tony; Hussain, Zahid; Jozwiak, Chris; Lanzara, Alessandra; Hasan, M. Zahid

    2007-01-19

    An ultra-high resolution beamline is being constructed at the Advanced Light Source (ALS) for the study of low energy excitations in strongly correlated systems with the use of high-resolution inelastic scattering and angle-resolved photoemission. This new beamline, given the acronym Merlin (for meV resolution line), will cover the energy range 10-150 eV. The monochromator has fixed entrance and exit slits and a plane mirror that can illuminate a spherical grating at the required angle of incidence (as in the SX-700 mechanism). The monochromator can be operated in two different modes. In the highest resolution mode, the energy scanning requires translating the monochromator chamber (total travel 1.1 m) as well as rotating the grating and the plane mirror in front of the grating. The resolution in this mode is practically determined by the slits width. In the second mode, the scanning requires rotating the grating and the plane mirror. This mode can be used to scan a few eV without a significant resolution loss. The source for the beamline is a 1.9 m long, 90 mm period quasi periodic EPU. The expected flux at the sample is higher than 1011 photons/s at a resolving power of 5 x 104 in the energy range 16-130 eV. A second set of gratings can be used to obtain higher flux at the expense of resolution.

  8. Little Boy neutron spectrum below 1 MeV

    SciTech Connect

    Evans, A.E.

    1984-01-01

    A high-resolution /sup 3/He ionization chamber of the type development by Cuttler and Shalev was used to study the neutron spectrum from the Little Boy mockup. Measurements were made at distances of 0.75 and 2.0 m and at angles of 0/sup 0/, 45/sup 0/, and 90/sup 0/ with respect to the axis of the assembly, which was operated at power levels from 8.6 to 450 mW. Detector efficiency as a function of energy as well as parameters for correction of pulse-height distributions for proton-recoil and wall effects were determined from a set of response functions for monoenergetic neutrons measured at the Los Alamos 3.75-MeV Van de Graaff Accelerator Facility. Pulse-shape discrimination was used to separate /sup 3/He-recoil pulses from the pulse-height distribution. The spectrum was found to be highly structured, with peaks corresponding to minima in the total neutron cross section of iron. In particular, 15% of the neutrons above the epithermal peak in energy were found to be in the 24-keV iron window. Lesser peaks out to 700 keV are also attributable to filtering action of the weapon's heavy iron casing. Data taken using experimental proton-recoil proportional counters are compared with the high-resolution spectra.

  9. Multipurpose 5-MeV linear induction accelerator

    SciTech Connect

    Birx, D.L.; Hawkins, S.A.; Poor, S.E.; Reginato, L.L. Smith, M.W.

    1984-06-11

    Although linear induction accelerators (LIAs) are quite reliable by most standards, they are limited in repeating rate, average power, and reliability because the final stage of energy delivery is based on spark gap performance. In addition, they have a low duty factor of operation. To provide a higher burst rate and greater reliability, the researchers used new technology to develop a magnetic pulse compression scheme that eliminates all spark gaps and exceeds requirements. The paper describes the scheme. The magnetic drive system can be tailored to drive induction cells from a few kA to over 10 kA at 500 kV, with average beam power levels in the megawatts. This new 5-MeV, 2.5-kA LIA under construction at the Lawrence Livermore National Laboratory (LLNL) will be used for the development of high brightness sources and will provide a test bed for the new technology, which should lead to LIAs that surpass the radio frequency linacs for efficiency and reliability, as well as fit other industrial applications, such as sewage sterilization.

  10. Multipurpose 5-MeV linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Birx, D. L.; Hawkins, S. A.; Poor, S. E.; Reginato, L. L.; Smith, M. W.

    1984-06-01

    Although linear induction accelerators (LIAs) are quite reliable by most standards, they are limited in repeating rate, average power, and reliability because the final stage of energy delivery is based on spark gap performance. In addition, they have a low duty factor of operation. To provide a higher burst rate and greater reliability, new technology was used to develop a magnetic pulse compression scheme that eliminates all spark gaps and exceeds requirements. The magnetic drive system are tailored to drive induction cells from a few kA to over 10 kA at 500 kV, with average beam power levels in the megawatts. This new 5-MeV, 2.5-kA LIA under construction at the Lawrence Livermore National Laboratory (LLNL) will be used for the development of high brightness sources and will provide a test bed for the new technology, which should lead to LIAs that surpass the radio frequency linacs for efficiency and reliability, as well as fit other industrial applications, such as sewage sterilization.

  11. Scintillator efficiency study with MeV x-rays

    NASA Astrophysics Data System (ADS)

    Baker, Stuart; Brown, Kristina; Curtis, Alden; Lutz, Stephen S.; Howe, Russell; Malone, Robert; Mitchell, Stephen; Danielson, Jeremy; Haines, Todd; Kwiatkowski, Kris

    2014-09-01

    We have investigated scintillator efficiency for MeV radiographic imaging. This paper discusses the modeled detection efficiency and measured brightness of a number of scintillator materials. An optical imaging camera records images of scintillator emission excited by a pulsed x-ray machine. The efficiency of various thicknesses of monolithic LYSO:Ce (cerium-doped lutetium yttrium orthosilicate) are being studied to understand brightness and resolution trade-offs compared with a range of micro-columnar CsI:Tl (thallium-doped cesium iodide) scintillator screens. The micro-columnar scintillator structure apparently provides an optical gain mechanism that results in brighter signals from thinner samples. The trade-offs for brightness versus resolution in monolithic scintillators is straightforward. For higher-energy x-rays, thicker materials generally produce brighter signal due to x-ray absorption and the optical emission properties of the material. However, as scintillator thickness is increased, detector blur begins to dominate imaging system resolution due to the volume image generated in the scintillator thickness and the depth of field of the imaging system. We employ a telecentric optical relay lens to image the scintillator onto a recording CCD camera. The telecentric lens helps provide sharp focus through thicker-volume emitting scintillators. Stray light from scintillator emission can also affect the image scene contrast. We have applied an optical light scatter model to the imaging system to minimize scatter sources and maximize scene contrasts.

  12. Abundance of low energy (50-150 MeV) antiprotons in cosmic rays

    NASA Technical Reports Server (NTRS)

    Biswas, S.; Stephens, S. A.; Apparao, K. M. V.; Durgaprasad, N.

    1985-01-01

    The progress is presented of the nuclear emulsion experiment to determine abundance of low energy antiprotons in cosmic rays. No antiprotons have been detected so far at upper limit of p/p less than or similar to 4 x .0001 in the energy range 50 MeV to 15 MeV.

  13. CRRES Medium Electrons A results

    SciTech Connect

    Vampola, A.L.

    1996-07-01

    The CRRES Medium Electrons A spectrometer data were used to examine the dynamics of electron fluxes in the inner zone after a series of magnetic storms increased electron fluxes by an order of magnitude down to as low as {ital L}=1.25. Comparisons of CRRES electron data with the AE8MAX particle model show good agreement in the inner zone in flux intensity, energy spectra, and pitch angle distributions up to about 600 keV pre-storm. Above 600 keV, the AE8MAX model has higher fluxes. The maximum energy spectrum over the range 0.15 MeV to 1.7 MeV observed at geosynchronous orbit altitude during the 16-month CRRES mission is presented and extrapolated to 10 MeV. The combined spectrum is characterized as the sum of three power-law segments with breakpoints at 0.8 and 2.0 MeV. The coefficients for the three segments are respectively {ital N}{sub {ital E}}=5{times}10{sup 7}{ital E}{sup {minus}1.5}, {ital N}{sub {ital E}}=4.5{times}10{sup 10}{ital E}{sup {minus}2.5}, and {ital N}{sub {ital E}}=4{times}10{sup 15}{ital E}{sup {minus}4}. Shielding of 155 mils Al equivalent would be required to prevent deep dielectric charging problems on geosynchronous satellites by an environment as severe as this maximum spectrum. {copyright} {ital 1996 American Institute of Physics.}

  14. Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory

    SciTech Connect

    Weathersby, S. P.; Brown, G.; Centurion, M.; Chase, T. F.; Coffee, R.; Corbett, J.; Eichner, J. P.; Frisch, J. C.; Fry, A. R.; Gühr, M.; Hartmann, N.; Hast, C.; Hettel, R.; Jobe, R. K.; Jongewaard, E. N.; Lewandowski, J. R.; Li, R. K.; Lindenberg, A. M.; Makasyuk, I.; May, J. E.; McCormick, D.; Nguyen, M. N.; Reid, A. H.; Shen, X.; Sokolowski-Tinten, K.; Vecchione, T.; Vetter, S. L.; Wu, J.; Yang, J.; Dürr, H. A.; Wang, X. J.

    2015-07-01

    Ultrafast electron probes are powerful tools, complementary to x-ray free-electron lasers, used to study structural dynamics in material, chemical, and biological sciences. High brightness, relativistic electron beams with femtosecond pulse duration can resolve details of the dynamic processes on atomic time and length scales. SLAC National Accelerator Laboratory recently launched the Ultrafast Electron Diffraction (UED) and microscopy Initiative aiming at developing the next generation ultrafast electron scattering instruments. As the first stage of the Initiative, a mega-electron-volt (MeV) UED system has been constructed and commissioned to serve ultrafast science experiments and instrumentation development. The system operates at 120-Hz repetition rate with outstanding performance. In this paper, we report on the SLAC MeV UED system and its performance, including the reciprocal space resolution, temporal resolution, and machine stability.

  15. Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory.

    PubMed

    Weathersby, S P; Brown, G; Centurion, M; Chase, T F; Coffee, R; Corbett, J; Eichner, J P; Frisch, J C; Fry, A R; Gühr, M; Hartmann, N; Hast, C; Hettel, R; Jobe, R K; Jongewaard, E N; Lewandowski, J R; Li, R K; Lindenberg, A M; Makasyuk, I; May, J E; McCormick, D; Nguyen, M N; Reid, A H; Shen, X; Sokolowski-Tinten, K; Vecchione, T; Vetter, S L; Wu, J; Yang, J; Dürr, H A; Wang, X J

    2015-07-01

    Ultrafast electron probes are powerful tools, complementary to x-ray free-electron lasers, used to study structural dynamics in material, chemical, and biological sciences. High brightness, relativistic electron beams with femtosecond pulse duration can resolve details of the dynamic processes on atomic time and length scales. SLAC National Accelerator Laboratory recently launched the Ultrafast Electron Diffraction (UED) and microscopy Initiative aiming at developing the next generation ultrafast electron scattering instruments. As the first stage of the Initiative, a mega-electron-volt (MeV) UED system has been constructed and commissioned to serve ultrafast science experiments and instrumentation development. The system operates at 120-Hz repetition rate with outstanding performance. In this paper, we report on the SLAC MeV UED system and its performance, including the reciprocal space resolution, temporal resolution, and machine stability. PMID:26233391

  16. Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory

    SciTech Connect

    Weathersby, S. P.; Brown, G.; Chase, T. F.; Coffee, R.; Corbett, J.; Eichner, J. P.; Frisch, J. C.; Fry, A. R.; Gühr, M.; Hartmann, N.; Hast, C.; Hettel, R.; Jobe, R. K.; Jongewaard, E. N.; Lewandowski, J. R.; Li, R. K. Lindenberg, A. M.; Makasyuk, I.; May, J. E.; McCormick, D.; and others

    2015-07-15

    Ultrafast electron probes are powerful tools, complementary to x-ray free-electron lasers, used to study structural dynamics in material, chemical, and biological sciences. High brightness, relativistic electron beams with femtosecond pulse duration can resolve details of the dynamic processes on atomic time and length scales. SLAC National Accelerator Laboratory recently launched the Ultrafast Electron Diffraction (UED) and microscopy Initiative aiming at developing the next generation ultrafast electron scattering instruments. As the first stage of the Initiative, a mega-electron-volt (MeV) UED system has been constructed and commissioned to serve ultrafast science experiments and instrumentation development. The system operates at 120-Hz repetition rate with outstanding performance. In this paper, we report on the SLAC MeV UED system and its performance, including the reciprocal space resolution, temporal resolution, and machine stability.

  17. Compact electron acceleration and bunch compression in THz waveguides.

    PubMed

    Wong, Liang Jie; Fallahi, Arya; Kärtner, Franz X

    2013-04-22

    We numerically investigate the acceleration and bunch compression capabilities of 20 mJ, 0.6 THz-centered coherent terahertz pulses in optimized metallic dielectric-loaded cylindrical waveguides. In particular, we theoretically demonstrate the acceleration of 1.6 pC and 16 pC electron bunches from 1 MeV to 10 MeV over an interaction distance of 20mm, the compression of a 1.6 pC 1 MeV bunch from 100 fs to 2 fs (50 times compression) over an interaction distance of about 18mm, and the compression of a 1.6 pC 10 MeV bunch from 100 fs to 1.61 fs (62 times) over an interaction distance of 42 cm. The obtained results show the promise of coherent THz pulses in realizing compact electron acceleration and bunch compression schemes. PMID:23609686

  18. An electrostatic quadrupole doublet focusing system for MeV heavy ions in MeV-SIMS

    NASA Astrophysics Data System (ADS)

    Seki, T.; Shitomoto, S.; Nakagawa, S.; Aoki, T.; Matsuo, J.

    2013-11-01

    The importance of imaging mass spectrometry (MS) for visualizing the spatial distribution of molecular species in biological tissues and cells is growing. In conventional SIMS with keV-energy ion beams, elastic collisions occur between projectiles and atoms in constituent molecules. The collisions produce fragments, making acquisition of molecular information difficult. In contrast, MeV-energy ion beams excite electrons near the surface and enhance the ionization of high-mass molecules, hence, fragment suppressed SIMS spectrum of ionized molecules can be obtained. This work is a further step on our previous report on the successful development of a MeV secondary ion mass spectrometry (MeV-SIMS) for biological samples. We have developed an electrostatic quadrupole doublet (EQ doublet) focusing system, made of two separate lenses, Q1 and Q2, to focus the MeV heavy ion beam and reduce measurement time. A primary beam of 6 MeV Cu4+ was focused with this EQ doublet. We applied 1120 V to the Q1 lens and 1430 V to the Q2 lens, and the current density increased by a factor of about 60. Using this arrangement, we obtained an MeV-SIMS image of 100 × 100 pixels of cholesterol-OH+ of cerebellum (m/z = 369.3) over a 4 mm × 4 mm field of view, with a pixel size of 40 μm within 5 min, showing that our EQ doublet reduces the measurement time of current imaging by a factor of about 30.

  19. Atomic sputtering in the analytical electron microscope

    SciTech Connect

    Bradley, C.R.; Zaluzec, N.J.

    1988-08-01

    The advent of UHV medium voltage electron microscopes has brought the microanalyst to a regime of operating conditions in which electron beam induced damage can now be introduced to metallic specimens of medium to high atomic number. We report upon calculations of electron beam induced atomic sputtering which will have bearing upon the next generation of medium voltage analytical electron microscopes. The cross-section calculations reported herein have been completed for all solid elements of the periodic table for incident electron energies up to 1.5 MeV. All computer codes needed to duplicate these computations are available through the EMMPDL. 12 refs., 2 figs., 1 tab.

  20. Experimental Search for a Heavy Electron

    DOE R&D Accomplishments Database

    Boley, C. D.; Elias, J. E.; Friedman, J. I.; Hartmann, G. C.; Kendall, H. W.; Kirk, P.N.; Sogard, M. R.; Van Speybroeck, L. P.; de Pagter, J. K.

    1967-09-01

    A search for a heavy electron of the type considered by Low and Blackmon has been made by studying the inelastic scattering of 5 BeV electrons from hydrogen. The search was made over a range of values of the mass of the heavy electron from 100 t0 1300 MeV. No evidence for such a particle was observed. Upper limits on the production cross sections were determined and employed to deducelimits on the values of the electron-photon-heavy electron coupling constant in Low and Blackmon=s theory.

  1. Suzaku Observations of Extreme MeV Blazar Swift J0746.3+2548

    SciTech Connect

    Watanabe, Shin; Sato, Rie; Takahashi, Tadayuki; Kataoka, Jun; Madejski, Greg; Sikora, Marek; Tavecchio, Fabrizio; Sambruna, Rita; Romani, Roger; Edwards, Philip G.; Pursimo, Tapio

    2008-12-01

    We report the Suzaku observations of the high luminosity blazar SWIFT J0746.3+2548 (J0746) conducted in November 2005. This object, with z = 2.979, is the highest redshift source observed in the Suzaku Guaranteed Time Observer (GTO) period, is likely to show high gamma-ray flux peaking in the MeV range. As a result of the good photon statistics and high signal-to-noise ratio spectrum, the Suzaku observation clearly confirms that J0746 has an extremely hard spectrum in the energy range of 0.3-24 keV, which is well represented by a single power-law with a photon index of {Lambda}{sub ph} {approx_equal} 1.17 and Galactic absorption. The multiwavelength spectral energy distribution of J0746 shows two continuum components, and is well modeled assuming that the high-energy spectral component results from Comptonization of the broad-line region photons. In this paper we search for the bulk Compton spectral features predicted to be produced in the soft X-ray band by scattering external optical/UV photons by cold electrons in a relativistic jet. We discuss and provide constraints on the pair content resulting from the apparent absence of such features.

  2. Characterization of MeV proton acceleration from double pulse irradiation of foil targets

    NASA Astrophysics Data System (ADS)

    Kerr, S.; Mo, M. Z.; Masud, R.; Tiedje, H. F.; Tsui, Y.; Fedosejevs, R.; Link, A.; Patel, P.; McLean, H. S.; Hazi, A.; Chen, H.; Ceurvorst, L.; Norreys, P.

    2014-10-01

    We report on the experimental characterization of proton acceleration from double-pulse irradiation of um-scale foil targets. Temporally separated sub-picosecond pulses have been shown to increase the conversion efficiency of laser energy to MeV protons. Here, two 700 fs, 1 ω pulses were separated by 1 to 5 ps; total beam energy was 100 J, with 5-20% of the total energy contained within the first pulse. In contrast to the ultraclean beams used in previous experiments, prepulse energies on the order of 10 mJ were present in the current experiments which appear to have a moderating effect on the enhancement. Proton beam measurements were made with radiochromic film stacks, as well as magnetic spectrometers. The effect on electron generation was measured using Kα emission from buried Cu tracer layers, while specular light diagnostics (FROG, reflection spectralon) indicated the laser coupling efficiency into the target. The results obtained will be presented and compared to PIC simulations. Work by LLNL was performed under the auspices of U.S. DOE under contract DE-AC52-07NA27344.

  3. Development of a 20 MeV Dielectric-Loaded Test Accelerator

    SciTech Connect

    Gold, S.H.; Kinkead, A.K.; Gai, W.; Power, J.G.; Konecny, R.; Jing, C.; Long, J.; Tantawi, S.G.; Nantista, C.D.; Fliflet, A.W.; Lombardi, M.; Lewis, D.; Bruce, R.W.; /Unlisted

    2007-04-13

    This paper presents a progress report on a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded test accelerator in the magnicon facility at NRL. The accelerator will be powered by an experimental 11.424-GHz magnicon amplifier that presently produces 25 MW of output power in a {approx}250-ns pulse at up to 10 Hz. The accelerator will include a 5-MeV electron injector originally developed at the Tsinghua University in Beijing, China, and can incorporate DLA structures up to 0.5 m in length. The DLA structures are being developed by ANL, and shorter test structures fabricated from a variety of dielectric materials have undergone testing at NRL at gradients up to {approx}8 MV/m. SLAC has developed components to distribute the power from the two magnicon output arms to the injector and to the DLA accelerating structure with separate control of the power ratio and relative phase. RWBruce Associates, Inc., working with NRL, has investigated means to join short ceramic sections into a continuous accelerator tube by a brazing process using an intense 83-GHz beam. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA test structure, and spectrometer, should take place within the next year.

  4. Development of a 20 MeV Dielectric-Loaded Test Accelerator

    SciTech Connect

    Gold, Steven H.; Fliflet, Arne W.; Lombardi, Marcie; Kinkead, Allen K.; Gai, Wei; Power, John G.; Konecny, Richard; Long, Jidong; Jing, Chunguang; Tantawi, Sami G.; Nantista, Christopher D.; Bruce, Ralph W.; Lewis, David III

    2006-11-27

    This paper presents a progress report on a joint project by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a dielectric-loaded test accelerator in the magnicon facility at NRL. The accelerator will be powered by an experimental 11.424-GHz magnicon amplifier that presently produces 25 MW of output power in a {approx}250-ns pulse at up to 10 Hz. The accelerator will include a 5-MeV electron injector originally developed at the Tsinghua University in Beijing, China, and can incorporate DLA structures up to 0.5 m in length. The DLA structures are being developed by ANL, and shorter test structures fabricated from a variety of dielectric materials have undergone testing at NRL at gradients up to {approx}8 MV/m. SLAC has developed components to distribute the power from the two magnicon output arms to the injector and to the DLA accelerating structure with separate control of the power ratio and relative phase. RWBruce Associates, Inc., working with NRL, has investigated means to join short ceramic sections into a continuous accelerator tube by a brazing process using an intense 83-GHz beam. The installation and testing of the first dielectric-loaded test accelerator, including injector, DLA test structure, and spectrometer, should take place within the next year.

  5. Design of a MeV, 4kA linear induction accelerator for flash radiography

    SciTech Connect

    Kulke, B.; Brier, R.; Chapin, W.

    1981-02-10

    For verifying the hydrodynamics of nuclear weapons design it is useful to have flash x-ray machines that can deliver a maximum dose in a minimum pulse length and with very high reliability. At LLNL, such a requirement was identified some years ago as 500 roentgens at one meter, in a 60 nsec pulse length. In response to this requirement, a linear induction accelerator was proposed to and funded by DOE in 1977. The design of this machine, called FXR, has now been completed and construction has begun. The FXR design extends the parameters of a similar machine that had been built and operated at LBL, Berkeley, some ten years ago. Using a cold cathode injector followed by 48 accelerator modules rated at 400 kV each, the FXR machine will accelerate a 4 kA electron beam pulse to 20 MeV final energy. Key design features are the generation and the stable transport of a low emittance (100 mr-cm) beam from a field emitter diode, the design of reliable, compact energy storage components such as Blumleins, feedlines and accelerator modules, and a computer-assisted control system.

  6. Neutron interrogation of high-enriched uranium by a 4 MeV linac

    NASA Astrophysics Data System (ADS)

    Lakosi, László; Nguyen, Cong Tam

    2008-07-01

    For revealing unauthorized transport (illicit trafficking) of nuclear materials, a non-destructive method reported earlier, utilizing a 4 MeV linear accelerator for photoneutron interrogation, was further developed. The linac served as a pulsed neutron source for assay of highly enriched uranium. Produced in beryllium or heavy water by bremsstrahlung, neutrons subsequently induced fission in the samples. Delayed neutrons were detected by a newly designed neutron collar built up of 14 3He counters embedded in a polyethylene moderator. A PC controlled multiscaler served as a time analyzer, triggering the detector startup by the beam pulse. Significant progress was achieved in enhancing the detector response, hence the sensitivity for revealing illicit material. A lower sensitivity limit of the order of 10 mg 235U was determined in a 20 s measurement time with a reasonable amount of beryllium (170 g) or of heavy water (100 g) and a mean electron current of 10 μA. Sensitivity can be further enhanced by increasing the measurement time.

  7. Precision Rosenbluth Measurement of the Proton Elastic Electromagnetic Form Factors and Their Ratio at Q^2=2.64, 3.20, and 4.10 GeV^2

    SciTech Connect

    Issam A. Qattan

    2005-12-01

    Due to the inconsistency in the results of the mupGEp/GMp ratio of the proton, as extracted from the Rosenbluth and recoil polarization techniques, high precision measurements of the e-p elastic scattering cross sections were made at Q{sup 2} = 2.64, 3.20, and 4.10 GeV{sup 2}. Protons were detected, in contrast to previous measurements where the scattered electrons were detected, which dramatically decreased-dependent systematic uncertainties and corrections. A single spectrometer measured the scattered protons of interest while simultaneous measurements at Q{sup 2} = 0.5 GeV{sup 2} were carried out using another spectrometer which served as a luminosity monitor in order to remove any uncertainties due to beam charge and target density fluctuations. The absolute uncertainty in the measured cross sections is {approx}3% for both spectrometers and with relative uncertainties, random and slope, below 1% for the higher Q{sup 2} protons, and below 1% random and 6% slope for the monitor spectrometer. The extracted electric and magnetic form factors were determined to 4%-7% for GEp and 1.5% for GMp. The ratio mupGEp/GMp was determined to 4%-7% and showed mupGEp/GMp {approx} 1.0. The results of this work are in agreement with the previous Rosenbluth data and inconsistent with high-Q{sup 2} recoil polarization results, implying a systematic difference between the two techniques.

  8. Structural and optical properties of 60B2O3-(20-x)Na2O-10PbO-10Al2O3:xTiO2:yNd2O3 glasses

    NASA Astrophysics Data System (ADS)

    de Souza, N. C. A.; Santos, C. C.; Guedes, I.; Dantas, N. O.; Vermelho, M. V. D.

    2013-10-01

    In this work we investigate the effect of replacing Na2O by TiO2 on the structural and spectroscopic characteristics of the Nd2O3-doped 60B2O3-(20-x)Na2O-10PbO-10Al2O3:xTiO2:yNd2O3 borate glass matrix. Measurements of X-ray patterns, glass temperatures (Tg), vibrational (Raman and infrared (IR)) and optical (absorption and emission) spectra were carried out. The trend of Tg, the Judd-Ofelt parameters and Nephelauxetic ratio as the TiO2 and Nd2O3 concentration increases was interpreted quantitatively and qualitatively in terms of the network bonds and coordination numbers. Measurements of Tg across the Nd-doped glass series for different levels of Ti suggests changes in the rigidity of the matrix due to change of coordination of boron oxide resulting from the BO4-BO3 back conversion effect. The changes observed in the Raman and IR spectra are related to the BO3 → BO4 conversion effect. The variation of the Judd-Ofelt parameters Ω and Ω indicates that the average rare earth-ligand radius decreases establishing an electronic density distribution when Nd3+ concentration increases. This effect is interpreted in terms of Judd-Ofelt parameters and by the bonding parameter b due to Nephelauxetic effect.

  9. Vacancy-related defects in n-type Si implanted with a rarefied microbeam of accelerated heavy ions in the MeV range

    NASA Astrophysics Data System (ADS)

    Capan, I.; Pastuović, Ž.; Siegele, R.; Jaćimović, R.

    2016-04-01

    Deep level transient spectroscopy (DLTS) has been used to study vacancy-related defects formed in bulk n-type Czochralski-grown silicon after implantation of accelerated heavy ions: 6.5 MeV O, 10.5 MeV Si, 10.5 MeV Ge, and 11 MeV Er in the single ion regime with fluences from 109 cm-2 to 1010 cm-2 and a direct comparison made with defects formed in the same material irradiated with 0.7 MeV fast neutron fluences up to 1012 cm-2. A scanning ion microprobe was used as the ion implantation tool of n-Cz:Si samples prepared as Schottky diodes, while the ion beam induced current (IBIC) technique was utilized for direct ion counting. The single acceptor state of the divacancy V2(-/0) is the most prominent defect state observed in DLTS spectra of n-CZ:Si samples implanted by selected ions and the sample irradiated by neutrons. The complete suppression of the DLTS signal related to the double acceptor state of divacancy, V2(=/-) has been observed in all samples irradiated by ions and neutrons. Moreover, the DLTS peak associated with formation of the vacancy-oxygen complex VO in the neutron irradiated sample was also completely suppressed in DLTS spectra of samples implanted with the raster scanned ion microbeam. The reason for such behaviour is twofold, (i) the local depletion of the carrier concentration in the highly disordered regions, and (ii) the effect of the microprobe-assisted single ion implantation. The activation energy for electron emission for states assigned to the V2(-/0) defect formed in samples implanted by single ions follows the Meyer-Neldel rule. An increase of the activation energy is strongly correlated with increasing ion mass.

  10. L-shell X-ray production cross sections of Ce, Nd, Sm, Eu, Gd, and Dy by impact of 14N2+ ions with energies between 7.0 MeV and 10.5 MeV

    NASA Astrophysics Data System (ADS)

    Murillo, G.; Méndez, B.; López-Monroy, J.; Miranda, J.; Villaseñor, P.

    2016-09-01

    L-shell X-ray production cross sections from the lanthanoid elements Ce, Nd, Sm, Eu, Gd, and Dy, induced by the impact of 14N2+ ions with energies in the interval 7.0 MeV to 10.5 MeV (0.50 MeV/μ to 0.75 MeV/μ), were measured and then compared with theoretical calculations obtained with the ECPSSR model with exact limits of integration (eCPSSR) and related corrections. These include the electron capture by the incoming ion and multiple ionizations of higher shells. Data from this work were contrasted with previously published L X-ray production cross sections for 14N2+ ion impact. As with other ions, a universal behavior is found when Lα and Lγ X-ray production cross sections are plotted as a function of reduced velocity parameters. The agreement with theoretical predictions was very good when the corrections were applied to the eCPSSR model.

  11. L-shell x-ray production cross sections in Nd, Gd, Ho, Yb, Au and Pb for 25-MeV carbon and 32-MeV oxygen ions

    SciTech Connect

    Andrews, M.C.; McDaniel, F.D.; Duggan, J.L.; Mehta, R.; Lapicki, G.; Miller, P.D.; Pepmiller, P.L.; Krause, H.; Rosseel, T.M.; Rayburn, L.A.

    1984-01-01

    L-shell x-ray production cross sections in /sub 60/Nd, /sub 64/Gd, /sub 67/Ho, /sub 70/Yb, /sub 79/Au and /sub 82/Pb have been measured for incident 25 MeV /sub 6//sup 12/C/sup +q/(q = 4,5,6) and 32 MeV /sub 8//sup 16/O/sup +q/(q = 5,7,8) ions. Measurements were made on targets ranging in thickness from 1 to 100 ..mu..g/cm/sup 2/. Echancement in the L-shell x-ray production cross section for projectiles with one or two K-shell vacancies over those for projectiles with no K-shell vacancies is observed. The sum of direct ionization to the continuum (DI) plus electron capture (EC) to the L,M,N ... shells and EC to the K-shell of the projectile have been extracted from the data. Calculations in the first Born approximation are approx. 10 times larger than the data. Predictions of the ECPSSR theory that accounts for the energy-loss, Coulomb deflection, perturbed-stationary state, and relativistic effects are in good agreement with the data for both ions.

  12. Prompt Recovery and Enhancement of the Earth's Outer Radiation Belt due to Relativistic Electron Injections

    NASA Astrophysics Data System (ADS)

    Tang, C. L.; Zhang, J.; Reeves, G. D.; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.

    2015-12-01

    We present multipoint observations (RBSP, GEOS and THEMIS) of the substorm electron injections during the substorm event on 16 August 2013. RBSP-A detected the MeV electron phase space density increased by an order of magnitude in about one hour at L* > 5.0. At L* = 4.4, the injected MeV electrons were also detected. It is suggested that the magnetic field dipolarization associated with the substorm injections alone can explain that the prompt recovery and enhancements of the relativistic electron (~ MeV) fluxes in the outer radiation belt. The observations of THEMIS-A also first presented that the near-Earth magnetotail at substorm onset is important in the MeV electron injection event: the enhanced fluxes of ~200 keV electrons are the source population and intense electromagnetic pulses are the driving source of MeV injected electrons. The pulse model is used to explain the dispersionless MeV injected electrons in the outer radiation belt observed by GEOS-13 and RBSP-A.

  13. Ultra-relativistic electrons in Jupiter's radiation belts.

    PubMed

    Bolton, S J; Janssen, M; Thorne, R; Levin, S; Klein, M; Gulkis, S; Bastian, T; Sault, R; Elachi, C; Hofstadter, M; Bunker, A; Dulk, G; Gudim, E; Hamilton, G; Johnson, W T K; Leblanc, Y; Liepack, O; McLeod, R; Roller, J; Roth, L; West, R

    2002-02-28

    Ground-based observations have shown that Jupiter is a two-component source of microwave radio emission: thermal atmospheric emission and synchrotron emission from energetic electrons spiralling in Jupiter's magnetic field. Later in situ measurements confirmed the existence of Jupiter's high-energy electron-radiation belts, with evidence for electrons at energies up to 20[?]MeV. Although most radiation belt models predict electrons at higher energies, adiabatic diffusion theory can account only for energies up to around 20[?]MeV. Unambiguous evidence for more energetic electrons is lacking. Here we report observations of 13.8[?]GHz synchrotron emission that confirm the presence of electrons with energies up to 50[?]MeV; the data were collected during the Cassini fly-by of Jupiter. These energetic electrons may be repeatedly accelerated through an interaction with plasma waves, which can transfer energy into the electrons. Preliminary comparison of our data with model results suggests that electrons with energies of less than 20[?]MeV are more numerous than previously believed. PMID:11875557

  14. An 800-MeV proton radiography facility for dynamic experiments

    SciTech Connect

    King, N.S.P.; Adams, K.; Ables, E.

    1998-12-01

    The capability has been successfully developed at the Los Alamos Nuclear Science Center (LANSCE) to utilize a spatially and temporally prepared 800-MeV proton beam to produce proton radiographs. A series of proton bursts are transmitted through a dynamically varying object and transported, via a unique magnetic lens system, to an image plane. The magnetic lens system permits correcting for the effects of multiple coulomb scattering which would otherwise completely blur the spatially transmitted information at the image plane. The proton radiographs are recorded on either a time integrating film plate or with a recently developed multi-frame electronic imaging camera system. The latter technique permits obtaining a time dependent series of proton radiographs with time intervals (modulo 358 ns) up to many microseconds and variable time intervals between images. One electronically shuttered, intensified, CCD camera is required per image. These cameras can detect single protons interacting with a scintillating fiber optic array in the image plane but also have a dynamic range which permits recording radiographs with better than 5% statistics for observation of detailed density variations in the object. A number of tests have been carried out to characterize the quality of the proton radiography system for absolute mass determination, resolution, and dynamic range. Initial dynamic experiments characterized the temporal and spatial behavior of shock propagation in high explosives with up to six images per experiment. Based on experience with the prototype system, a number of upgrades are being implemented including the anticipated capability for enhanced mass discrimination through differential multiple coulomb scattering radiographs and more images with improved imaging techniques.

  15. Response of the Li-7-enriched Cs2LiYCl6:Ce (CLYC-7) scintillator to 6-60 MeV neutrons

    NASA Astrophysics Data System (ADS)

    Woolf, Richard S.; Hutcheson, Anthony L.; Phlips, Bernard F.; Wulf, Eric A.

    2015-12-01

    We discuss a test campaign designed to irradiate the 7Li-enriched Cs2LiYCl6:Ce3+ (CLYC-7) scintillator with 6-60 MeV neutrons using the cyclotron located at the Crocker Nuclear Laboratory in Davis, CA. CLYC-7 is a newly developed scintillator that exhibits the ability to make good γ-ray measurements and has the ability to detect and discriminate fast neutrons via pulse shape discrimination (PSD) while functioning as a spectrometer. This allows a single detector to make good measurement of both stimuli simultaneously. The response of this scintillation detector has been investigated below 20 MeV [1] but has yet to be explored for energies greater than 20 MeV. Understanding the spectral and pulse shape response across a broad energy range is important for any radiation detection instrumentation capable of detecting multiple species. At the highest energies sampled, the CLYC-7 PSD demonstrated not only the standard electron/proton separation expected in a mixed γ/n field but the ability to discriminate locally produced deuterons, tritons and α particles. We show the results from the four different neutron beam energies sampled during the experiment. Lastly, we present the results obtained for relating the light output equivalence between electrons and protons/deuterons.

  16. Formation of the 0.511.-MeV line in solar flares. [statistical mechanics of line spectra for gamma rays

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Joyce, G.; Ramaty, R.; Werntz, C.

    1976-01-01

    The gamma-ray line produced at 0.51-MeV was studied and is shown to be the result of either of free annihilation of positrons with electrons or of the decay of positronium by 2-photon emission. Positron annihilation from the bound state of positronium may also proceed by 3-photon emission, resulting in a continuum with energies up to 0.51-MeV. Accurate calculations of the rates of free annihilation and positronium formation in a solar-flare plasma are presented. Estimates of the positronium-formulation rates by charge exchange and the rates of dissociation and quenching are also considered. The temperature and density dependence of the ratio of 3-photon to 2-photon emission was obtained. It is shown that when the ratio of free electrons to neutral atoms in the plasma is approximately unity or greater, the Doppler width of the 0.51-MeV line is a function of the temperature of the annihilation region. For the small ion densities characteristics of the photosphere, the width is predominantly a function of the density.

  17. Ultrarelativistic electrons in the Van Allen belts: RPS observations and Geant4 simulations

    NASA Astrophysics Data System (ADS)

    Looper, M. D.; Mazur, J. E.; O'Brien, T. P., III; Blake, J. B.; George, J. S.

    2015-12-01

    The Relativistic Proton Spectrometer (RPS) aboard the Van Allen Probes spacecraft is designed to measure protons from about 60 MeV to multiple GeV, but it is also sensitive to electrons above several MeV. Its Cherenkov subsystem provides energy resolution for protons above a few hundred MeV, and electrons at extremely high energies, around 50 MeV and above, can also produce high levels of Cherenkov light. While mapping protons in the inner Van Allen Belt with RPS, Mazur et al. (Fall 2014 AGU meeting, paper SM22A-02) observed a concentration of particle events around L = 2 with Cherenkov light corresponding to protons at energies well above the limit for stable trapping there. We present a preliminary analysis that shows that the patterns of the Cherenkov light distribution are consistent with these particle events instead being caused by electrons at energies of at least several tens of MeV. This energy range is well above that expected from magnetospheric energization, even by a violent event like the March 1991 shock, which injected electrons peaked around 15 MeV (Looper et al., GRL 1994, doi:10.1029/94GL01586). We discuss the possibility that these electrons are instead due to the decay of pions and muons produced by cosmic-ray interactions with the atmosphere, with a characteristic energy set by the pion rest mass of 140 MeV.

  18. FEMTO SECOND ELECTRON BEAM DIFFRACTION USING A PHOTOCATHODE RF GUN.

    SciTech Connect

    WANG,X.J.WU,Z.IHEE,H.

    2003-05-12

    One of the 21st century scientific frontiers is to explore the molecule structure transition on the femtosecond time scale. X-ray free electron laser (XFEL) is one of the tools now under development for investigating femto-second structure transition. We are proposing an alternative technique--femto-second electron diffraction based on a photocathode RF gun. We will present a design of a kHz femto-seconds electron diffraction system based on a photocathode RF gun. Our simulation shows that, the photocathode RF gun can produce 100 fs (FWHM) electron bunch with millions electrons at about 2 MeV. This is at least one order of magnitude reduction in bunch length, and two orders of magnitude increase in number of electrons comparing to present time-resolved electron diffraction system. We will also discuss various issues and limitations related to MeV electron diffraction.

  19. Radiation hardness of n-type SiC Schottky barrier diodes irradiated with MeV He ion microbeam

    NASA Astrophysics Data System (ADS)

    Pastuović, Željko; Capan, Ivana; Cohen, David D.; Forneris, Jacopo; Iwamoto, Naoya; Ohshima, Takeshi; Siegele, Rainer; Hoshino, Norihiro; Tsuchida, Hidekazu

    2015-04-01

    We studied the radiation hardness of 4H-SiC Schottky barrier diodes (SBD) for the light ion detection and spectroscopy in harsh radiation environments. n-Type SBD prepared on nitrogen-doped (∼4 × 1014 cm-3) epitaxial grown 4H-SiC thin wafers have been irradiated by a raster scanning alpha particle microbeam (2 and 4 MeV He2+ ions separately) in order to create patterned damage structures at different depths within a sensitive volume of tested diodes. Deep Level Transient Spectroscopy (DLTS) analysis revealed the formation of two deep electron traps in the irradiated and not thermally treated 4H-SiC within the ion implantation range (E1 and E2). The E2 state resembles the well-known Z1/2 center, while the E1 state could not be assigned to any particular defect reported in the literature. Ion Beam Induced Charge (IBIC) microscopy with multiple He ion probe microbeams (1-6 MeV) having different penetration depths in tested partly damaged 4H-SiC SBD has been used to determine the degradation of the charge collection efficiency (CCE) over a wide fluence range of damaging alpha particle. A non-linear behavior of the CCE decrease and a significant degradation of the spectroscopic performance with increasing He ion fluence were observed above the value of 1011 cm-2.

  20. Tailoring the Neutron Spectrum from a 14-MeV Neutron Generator to Approximate a Spontaneous-Fission Spectrum

    SciTech Connect

    James Simpson; David Chichester

    2011-06-01

    Many applications of neutrons for non-invasive measurements began with isotopic sources such as AmBe or Cf-252. Political factors have rendered AmBe undesirable in the United States and other countries, and the supply of Cf-252 is limited and significantly increasing in price every few years. Compact and low-power deuterium-tritium (DT) electronic neutron generators can often provide sufficient flux, but the 14-MeV neutron spectrum is much more energetic (harder) than an isotopic neutron source. A series of MCNP simulations were run to examine the extent to which the 14-MeV DT neutron spectrum could be softened through the use of high-Z and low-Z materials. Some potential concepts of operation require a portable neutron generator system, so the additional weight of extra materials is also a trade-off parameter. Using a reference distance of 30 cm from the source, the average neutron energy can be lowered to be less than that of either AmBe or Cf-252, while obtaining an increase in flux at the reference distance compared to a bare neutron generator. This paper discusses the types and amounts of materials used, the resulting neutron spectra, neutron flux levels, and associated photon production.

  1. Tailoring the Neutron Spectrum from a 14-MeV Neutron Generator to Approximate a Spontaneous-Fission Spectrum

    NASA Astrophysics Data System (ADS)

    Simpson, J. D.; Chichester, D. L.

    2011-12-01

    Many applications of neutrons for non-invasive measurements began with isotopic sources such as AmBe or Cf-252. Political factors have rendered AmBe undesirable in the United States and other countries, and the supply of Cf-252 is limited and significantly increasing in price every few years. Compact and low-power deuterium-tritium (DT) electronic neutron generators can often provide sufficient flux, but the 14-MeV neutron spectrum is much more energetic (harder) than an isotopic neutron source. A series of MCNP simulations was run to examine the extent to which the 14-MeV DT neutron spectrum could be softened through the use of high-Z and low-Z materials. Some potential concepts of operation require a portable neutron generator system, so the additional weight of extra materials is also a trade-off parameter. Using a reference distance of 30 cm from the source, the average neutron energy can be lowered to be less than that of either AmBe or Cf-252, while obtaining an increase in flux at the reference distance compared to a bare neutron generator. This paper discusses the types and amounts of materials used, the resulting neutron spectra, neutron flux levels, and associated photon production.

  2. Tailoring the Neutron Spectrum from a 14-MeV Neutron Generator to Approximate a Spontaneous-Fission Spectrum

    SciTech Connect

    Simpson, J. D.; Chichester, D. L.

    2011-12-13

    Many applications of neutrons for non-invasive measurements began with isotopic sources such as AmBe or Cf-252. Political factors have rendered AmBe undesirable in the United States and other countries, and the supply of Cf-252 is limited and significantly increasing in price every few years. Compact and low-power deuterium-tritium (DT) electronic neutron generators can often provide sufficient flux, but the 14-MeV neutron spectrum is much more energetic (harder) than an isotopic neutron source. A series of MCNP simulations was run to examine the extent to which the 14-MeV DT neutron spectrum could be softened through the use of high-Z and low-Z materials. Some potential concepts of operation require a portable neutron generator system, so the additional weight of extra materials is also a trade-off parameter. Using a reference distance of 30 cm from the source, the average neutron energy can be lowered to be less than that of either AmBe or Cf-252, while obtaining an increase in flux at the reference distance compared to a bare neutron generator. This paper discusses the types and amounts of materials used, the resulting neutron spectra, neutron flux levels, and associated photon production.

  3. Photonuclear fission with quasimonoenergetic electron beams from laser wakefields

    SciTech Connect

    Reed, S. A.; Chvykov, V.; Kalintchenko, G.; Matsuoka, T.; Rousseau, P.; Yanovsky, V.; Vane, C. R.; Beene, J. R.; Stracener, D.; Schultz, D. R.; Maksimchuk, A.

    2006-12-04

    Recent advancements in laser wakefield accelerators have resulted in the generation of low divergence, hundred MeV, quasimonoenergetic electron beams. The bremsstrahlung produced by these highly energetic electrons in heavy converters includes a large number of MeV {gamma} rays that have been utilized to induce photofission in natural uranium. Analysis of the measured delayed {gamma} emission demonstrates production of greater than 3x10{sup 5} fission events per joule of laser energy, which is more than an order of magnitude greater than that previously achieved. Monte Carlo simulations model the generated bremsstrahlung spectrum and compare photofission yields as a function of target depth and incident electron energy.

  4. Surface modification using MeV ion beams

    NASA Technical Reports Server (NTRS)

    Tombrello, T. A.

    1983-01-01

    Electronic excitation induced by MeV/amu ion beams in a variety of materials has been employed successfully for a number of applications. The examples that will be presented are: modification of the surface reflectivities of optical materials; sputter-erosion of dielectrics; and enhancement of the adhesion of thin film coatings. All of these effects arise from the loss of energy by the ion beam to electrons in the target material; the mechanisms involved are at best qualitatively understood. This paper will stress not only the exploitation of such high energy bombardment techniques but will also briefly review attempts to expose the underlying causes.

  5. Calculation of inelastic electron-nucleus scattering form factors of 29Si

    NASA Astrophysics Data System (ADS)

    Salman, A. D.; Al-Dahan, N.; Sharrad, F. I.; Hossain, I.

    2014-08-01

    Inelastic electron scattering form factors for 29Si nucleus with total angular momentum and positive parity (Jπ) and excited energy (3/2+, 1.273 MeV; 5/2+, 2.028 MeV; 3/2+, 2.425 MeV and 7/2+, 4.079 MeV) have been calculated using higher energy configurations outside the sd-shell. The calculations of inelastic form factors up to the first- and second-order with and without core-polarization (CP) effects were compared with the available experimental data. The calculations of inelastic electron scattering form factors up to the first-order with CP effects are in agreement with the experimental data, excepted for states 3/2+(1.273 MeV) and 5/2+(2.028 MeV) and without this effect are failed for all states. Furthermore, the calculations of inelastic electron scattering form factors up to the second-order with CP effects are in agreement with the experimental data for 3/2+(1.273 MeV) and 5/2+(2.028 MeV).

  6. ON THE SPECTRUM OF THE PULSED GAMMA-RAY EMISSION OF THE CRAB PULSAR FROM 10 MeV TO 400 GeV

    SciTech Connect

    Chkheidze, N.; Machabeli, G.; Osmanov, Z.

    2013-08-20

    In the present paper, a self-consistent theory, interpreting VERITAS and the MAGIC observations of the very high-energy pulsed emission from the Crab pulsar, is considered. The photon spectrum between 10 MeV and 400 GeV can be described by two power-law functions with spectral indices of 2.0 and 3.8. The source of the pulsed emission above 10 MeV is assumed to be synchrotron radiation, which is generated near the light cylinder during the quasi-linear stage of the cyclotron instability. The emitting particles are the primary beam electrons with Lorentz factors up to 10{sup 9}. Such high energies of beam particles can be reached due to Landau damping of the Langmuir waves in the light cylinder region.

  7. Deuteron Photodisintegration between Egamma=2.4 MeV and 4.0 MeV

    NASA Astrophysics Data System (ADS)

    Czakon, Nicole; Tornow, Werner

    2002-10-01

    Deuteron Photodisintegration between Eγ=2.4 and 4.0 MeV W.Tornow, N.G. Czakon, C.R. Howell, A. Hutcheson, J.H. Kelley, V.N. Litvinenko, S. Mikhailov, I.V. Pinayev, and G.J. Weisel The p(n,γ)d reaction has no published data in the relevant big-bang nucleosynthesis (BBN) energy region. Theoretical calculations, such as the ones by Arenhoevel and Sanzone [1], contribute significant uncertainties in the relative abundances of elements produced BBN. This experiment was motivated by the varying theoretical calculations and the lack of experimental data. We measured the analyzing power for the ^2H(γ,n)p reaction at 90^o for eight different energies. A mono-energetic, linearly polarized g-ray beam was incident on a deuterated liquid scintillator (C_6D_12). The scattered neutrons were detected two detectors, mounted at θ = 90^o in the plane of the g-ray polarization, and two detectors, mounted at θ = 90^o in the plane perpendicular to the γ-ray polarization plane. The neutron time of flight and the proton energy were recorded in the deuterated scintillator. Monte-Carlo calculations have been performed to simulate finite-geometry and multiple scattering on Arenhövel's calculations [3]. Our data for the proton analyzing power will be compared to Rupak's predictions [2]. References 1. H. Arenhövel and M. Sanzone, Photodisintegration of the Deuteron: A Review of Theory and Experiment (Springer Verlag, 1991). 2. G. Rupak, Nucl. Phys. A678, 405 (2000). 3. H. Arenhövel, Private communication (2001).

  8. Observations of gamma radiation between 0.4 MeV and 7 MeV at balloon altitudes using a Compton telescope

    NASA Astrophysics Data System (ADS)

    Lockwood, J. A.; Webber, W. R.; Friling, L. A.; Macri, J.; Hsieh, L.

    1981-09-01

    Balloon-borne measurements of the atmospheric and diffuse gamma-ray flux in the energy range 0.4-7.0 MeV with a Compton telescope, which included pulse-shape discrimination of the first scattering detector and a time-of-flight system between the first and second detector elements, are reported. Comparison of the diffuse cosmic gamma-ray flux to the atmospheric gamma rays indicates that 0.2-5.0 MeV is the optimum energy range for measurements made at the top of the earth's atmosphere. The measured total atmospheric gamma-ray flux between zero and 40 deg has an energy spectrum that agrees with the calculations of Ling (1975). Observations indicate that the ratio of the diffuse to atmospheric gamma ray fluxes at 3.5 g/sq cm is a maximum, about 1.0, between 0.7 and 3.0 MeV.

  9. Angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei

    NASA Astrophysics Data System (ADS)

    Bystritsky, V. M.; Grozdanov, D. N.; Zontikov, A. O.; Kopach, Yu. N.; Rogov, Yu. N.; Ruskov, I. N.; Sadovsky, A. B.; Skoy, V. R.; Barmakov, Yu. N.; Bogolyubov, E. P.; Ryzhkov, V. I.; Yurkov, D. I.

    2016-07-01

    The work is devoted to measuring the angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei. A portable ING-27 neutron generator (designed and fabricated at VNIIA, Moscow) with a built-in 64-pixel silicon α-detector was used as a source of tagged neutrons. The γ-rays of characteristic nuclear radiation from 12C were detected with a spectrometric system that consisted of 22 γ-detectors based on NaI(Tl) crystals arranged around the carbon target. The measured angular distribution of 4.43-MeV γ-rays is analyzed and compared with the results of other published experimental works.

  10. Short electron bunch generation using single-cycle ultrafast electron guns

    NASA Astrophysics Data System (ADS)

    Fallahi, Arya; Fakhari, Moein; Yahaghi, Alireza; Arrieta, Miguel; Kärtner, Franz X.

    2016-08-01

    We introduce a solution for producing ultrashort (˜fs ) high charge (˜pC ) from ultracompact guns utilizing single-cycle THz pulses. We show that the readily available THz pulses with energies as low as 20 μ J are sufficient to generate multi-10 keV electron bunches. Moreover, it is demonstrated that THz energies of 2 mJ are sufficient to generate relativistic electron bunches with higher than 2 MeV energy. The high acceleration gradients possible in the structures provide 30 fs electron bunches at 30 keV energy and 45 fs bunches at 2 MeV energy. These structures will underpin future devices for strong field THz physics in general and miniaturized electron guns, in which the high fields combined with the short pulse duration enable electron beams with ultrahigh brightness.

  11. Energy Measurements of Trapped Electrons from a Plasma Wakefield Accelerator

    SciTech Connect

    Kirby, Neal; Auerbach, David; Berry, Melissa; Blumenfeld, Ian; Clayton, Christopher E.; Decer, Franz-Josef; Hogan, Mark J.; Huang, Chengkun; Ischebeck, Rasmus; Iverson, Richard; Johnson, Devon; Joshi, Chadrashekhar; Katsouleas, Thomas; Lu, Wei; Marsh, Kenneth A.; Mori, Warren B.; Muggli, Patric; Oz, Erdem; Siemann, Robert H.; Walz, Dieter; Zhou, Miaomiao; /SLAC /UCLA /Southern California U.

    2007-01-03

    Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC indicate trapping of plasma electrons. More charge came out of than went into the plasma. Most of this extra charge had energies at or below the 10 MeV level. In addition, there were trapped electron streaks that extended from a few GeV to tens of GeV, and there were mono-energetic trapped electron bunches with tens of GeV in energy.

  12. Pion absorption processes. [32 to 74 MeV

    SciTech Connect

    Doss, K G.R.

    1980-04-01

    Proton and deuteron production from low-energy pion absorption in light nuclei leading to discrete and continuum states were measured. The LEP beam line at LAMPF was used with a stack of 8 intrinsic germanium crystals. The proton energy spectra are in general characterized by a broad bump at an energy approximately corresponding to ..pi../sup +/d ..-->.. pp reaction kinematics, suggestive of pion absorption on 2 nucleons. The energy-integrated cross-section for production of deuterons has an angular distribution similar to that for production of protons. The dependence of the total pion absorption cross-section on A is explained using a semi-classical model for pion transport in nuclei. The (..pi../sup +/,p) as well as (..pi../sup +/,d) reactions generally favor transitions involving larger angular momentum transfer to the residual nucleus when states of similar nuclear structure are considered. The low-energy excitation spectra from the (..pi../sup +/,p) reaction are similar to the spectra from (p,d) reaction on /sup 12/C and /sup 13/C. However, a calculation of the (..pi.. = ,p) cross-section using the measured (p,d) reaction with the formulation of Wilkin to relate the two reactions is in moderate disagreement with the measured (..pi../sup +/,p) cross-sections. The excitation spectra from the (..pi../sup +/,p) reaction indicte the importance of two-step processes for the reaction. The (..pi../sup +/,d) reaction leading to the ground state of -- residual nucleus has been seen for /sup 7/Li, /sup 12/C, and /sup 13/C targets. The measured cross section for the /sup 12/C(..pi../sup +/,d)/sup 10/C reaction to the 2/sup +/ state is much higher than that for the ground state. For the case of /sup 18/O, no counts were seen for excitation energy of < 10 MeV, at a sensitivity of approx. 100 nb/sr count. These features indicate a possible failure of the model of Betz and Kerman for the (..pi../sup +/,d) reaction.

  13. Operation and improvements of the Fermilab 400 MeV Linac

    SciTech Connect

    Allen, L.J.; Popovic, M.; Schmidt, C.W.

    1996-09-01

    The 400 MeV Fermilab Linac Upgrade commissioning began August 28, 1993. High energy physics collider operation (run 1b) began in November 1993 and ended March 1, 1996. The Linac, operating at 98% reliability, provided 400 MeV H{sup -} beam to the Booster and 66 MeV H{sup -} beam to the Neutron Therapy Facility. During this time, the beam intensity, which initially was administratively set to 35 MA, rose to a peak of 50 mA while losses decreased significantly. This paper discusses the Linac operation and reliability since the Upgrade.

  14. Spectral measurements of neutrons produced by 52 MeV protons with activation detectors

    NASA Astrophysics Data System (ADS)

    Shin, Kazuo; Saito, Takatsugu; Fujii, Masahiko; Nakamura, Takashi

    The accuracy of the neutron spectral measurement of energy up to ˜40 MeV with activation detectors was examined using high energy neutrons from thick targets bombarded by 52 MeV protons. The measured activation rates were unfolded with the modified SAND-II code and compared with the neutron spectra measured by the NE-213 scintillator. Quite good agreement in absolute values was obtained between the spectra recorded by these two different detectors. The activation detector was shown to be useful for neutron spectroscopy at energies higher than ˜ 10 MeV.

  15. Ion beam processing of advanced electronic materials

    SciTech Connect

    Cheung, N.W.; Marwick, A.D.; Roberto, J.B.; International Business Machines Corp., Yorktown Heights, NY . Thomas J. Watson Research Center; Oak Ridge National Lab., TN )

    1989-01-01

    This report contains research programs discussed at the materials research society symposia on ion beam processing of advanced electronic materials. Major topics include: shallow implantation and solid-phase epitaxy; damage effects; focused ion beams; MeV implantation; high-dose implantation; implantation in III-V materials and multilayers; and implantation in electronic materials. Individual projects are processed separately for the data bases. (CBS)

  16. Linearity of photoconductive GaAs detectors to pulsed electrons

    SciTech Connect

    Ziegler, L.H.

    1995-12-31

    The response of neutron damaged GaAs photoconductor detectors to intense, fast (50 psec fwhm) pulses of 16 MeV electrons has been measured. Detectors made from neutron damaged GaAs are known to have reduced gain, but significantly improved bandwidth. An empirical relationship between the observed signal and the incident electron fluence has been determined.

  17. Production of slow-positron beams with an electron linac

    SciTech Connect

    Howell, R.H.; Alvarez, R.A.; Stanek, M.

    1982-03-26

    Intense, pulsed beams of low-energy positrons have been produced by a high-energy beam from an electron linac. The production efficiency for low-energy positrons has been determined for electrons with 60 to 120 MeV energy, low-energy positron beams from a linac can be of much higher intensity than those beams currently derived from radioactive sources.

  18. Intense Auroral Activity (HILDCAAs) Observation as a Predictor of Radiation Belt Relativistic Electrons

    NASA Astrophysics Data System (ADS)

    Hajra, R.; Tsurutani, B.; Echer, E.

    2015-12-01

    Relativistic (E > 0.6, > 2.0, and > 4.0 MeV) electrons at geosynchronous orbit during solar cycle 23 are well-correlated with the intervals of high-intensity, long-duration, continuous AE activity (HILDCAA) events. Cluster-4 passes were examined for electromagnetic chorus waves in the 5 < L < 10 and 0 < MLT < 12 region. All the HILDCAA events under study were found to be characterized by enhanced whistler-mode chorus waves and flux enhancements of magnetospheric relativistic electrons of all three energies compared to the pre-event flux levels. CIR magnetic storms followed by HILDCAA events show almost the same relativistic electron signatures. It is concluded that the CIR storms have little to do with the acceleration of relativistic electrons. The response of the energetic electrons to HILDCAAs was found to vary with solar cycle phase. The initial electron fluxes were lower for events occurring during the ascending and solar maximum (AMAX) phases than for events occurring during the descending and solar minimum (DMIN) phases. The flux increases for the DMIN-phase events were > 50% larger than for the AMAX-phase events. It is concluded that electrons are accelerated to relativistic energies most often and most efficiently during the DMIN-phases of the solar cycle. Enhanced E > 0.6 MeV electron fluxes at geosynchronous orbit were first detected ~1 day after the statistical onset of HILDCAAs, E > 2.0 MeV electrons after ~1.5 days, and E > 4.0 MeV electrons after ~2.5 days. It is proposed that relativistic electrons are bootstrapped from high energy electrons: the E > 0.6 MeV electrons are accelerated from HILDCAA-injected E ~100 keV electrons, the E > 2.0 MeV electrons from the E > 0.6 MeV electron population, and consequently the E > 4.0 MeV electrons are accelerated from the E > 2.0 MeV population, etc. Relativistic electron acceleration and decay timescales will be provided for wave-particle investigators to attempt to match their models to empirically derived

  19. Photoneutron interrogation of low-enriched uranium induced by bremsstrahlung from a 4 MeV linac

    NASA Astrophysics Data System (ADS)

    Lakosi, L.; Tam Nguyen, C.; Bagi, J.

    2008-01-01

    Revealing smuggled nuclear material by passive γ-detection is hindered, because the weak radiation can easily be shielded. Neutrons, as penetrate shielding, represent a detection potential, by inducing fission in the nuclear material. A 4 MeV linear accelerator was used as a pulsed neutron source for active interrogation of U-bearing material. Produced in heavy water by bremsstrahlung, neutrons subsequently induced fissions in UO2 samples. Delayed fission neutrons were detected in a neutron collar built up by 3He counters in a polyamide container. The counters were gated to be detached from high voltage during the electron pulse. Irradiation-measurement cycles were carried out with a 25 Hz pulse repetition rate as optimum setting. The time analyser start-up was externally triggered and synchronised by the electron beam pulse. The response of the system was studied as a function of the intensity of the electron current, the amount of heavy water, U enrichment, and total U content. Sensitivity limit was achieved as 0.5 g 235U and/or 30 g 238U in a 20 s measurement time (500 cycles) with the amount of heavy water of 100 g and a mean electron current of 2 μA. Because of the long decay time of the prompt (interrogating and fission) neutron pulse, about a half of the time interval (40 ms) between pulses is only available for counting delayed neutrons.

  20. Positron annihilation lifetime measurement and X-ray analysis on 120 MeV Au+7 irradiated polycrystalline tungsten

    NASA Astrophysics Data System (ADS)

    Dube, Charu Lata; Kulriya, Pawan Kumar; Dutta, Dhanadeep; Pujari, Pradeep K.; Patil, Yashashri; Mehta, Mayur; Patel, Priyanka; Khirwadkar, Samir S.

    2015-12-01

    In order to simulate radiation damages in tungsten, potential plasma facing materials in future fusion reactors, surrogate approach of heavy ion irradiation on polycrystalline tungsten is employed. Tungsten specimen is irradiated with gold heavy ions of energy 120 MeV at different fluences. Positron annihilation lifetime measurements are carried out on pristine and ion beam irradiated tungsten specimens. The variation in positron annihilation lifetime in ion irradiated specimens confirms evolution of vacancy clusters under heavy ion irradiation. The pristine and irradiated tungsten specimens have also been characterized for their microstructural, structural, electrical, thermal, and mechanical properties. X-ray diffractograms of irradiated tungsten specimens show structural integrity of polycrystalline tungsten even after irradiation. Nevertheless, the increase in microstrain, electrical resistivity and microhardness on irradiation indicates creation of lattice damages inside polycrystalline tungsten specimen. On the other hand, the thermal diffusivity has not change much on heavy ion irradiation. The induction of damages in metallic tungsten is mainly attributed to high electronic energy loss, which is 40 keV/nm in present case as obtained from SRIM program. Although, concomitant effect of nuclear losses on damage creation cannot be ignored. It is believed that the energy received by the electronic system is being transferred to the atomic system by electron-phonon coupling. Eventually, elastic nuclear collisions and the transfer of energy from electronic to atomic system via inelastic collision is leading to significant defect generation in tungsten lattice.

  1. Comparison of bactericidal efficiency of 7.5 MeV X-rays, gamma-rays, and 10 MeV e-beams

    NASA Astrophysics Data System (ADS)

    Song, Beom-Seok; Lee, Yunjong; Moon, Byeong-Geum; Go, Seon-Min; Park, Jong-Heum; Kim, Jae-Kyung; Jung, Koo; Kim, Dong-Ho; Ryu, Sang-Ryeol

    2016-08-01

    This study was performed to verify the feasibility of 7.5 MeV X-rays for food pasteurization through a comparison of the bactericidal efficiency with those of other sources for selected bacterial pathogens. No significant differences were observed between the overall bactericidal efficiency for beef-inoculated pathogens based on the uncertainty of the absorbed dose and variations in bacterial counts. This result supported that all three irradiation sources were effective for inactivation of food-borne bacteria and that 7.5 MeV X-rays may be used for food pasteurization.

  2. An improved time of flight gamma-ray telescope to monitor diffuse gamma-ray in the energy range 5 MeV - 50 MeV

    NASA Technical Reports Server (NTRS)

    Bui-Van, A.; Sabaud, C.; Vedrenne, G.; Agrinier, B.; Gouiffes, C.; Dacostafereiraneri, A.; Lavigne, J. M.

    1985-01-01

    A time of flight measuring device is the basic triggering system of most of medium and high energy gamma-ray telescopes. A simple gamma-ray telescope has been built in order to check in flight conditions the functioning of an advanced time of flight system. The technical ratings of the system are described. This telescope has been flown twice with stratospheric balloons, its axis being oriented at various Zenital directions. Flight results are presented for diffuse gamma-rays, atmospheric secondaries, and various causes of noise in the 5 MeV-50 MeV energy range.

  3. Dynamics of energetic plasma sheet electrons

    NASA Astrophysics Data System (ADS)

    Burin Des Roziers, Edward

    2009-06-01

    The dynamics of energetic plasma sheet electrons plays an important role in many geomagnetic processes. The intent of this thesis is to extend the current understanding of the relationship between the solar wind and energetic plasma sheet electrons (~> 40 keV ), as well as the variability of these electrons within the plasma sheet. The statistical relationship between tens of keV plasma sheet electrons and the solar wind, as well as > 2 MeV geosynchronous electrons, is investigated, using plasma sheet measurements from Cluster (2001 - 2005) and Geotail (1998 - 2005), and concurrent solar wind measurements from ACE. Statistically, plasma sheet electron flux variations are compared to solar wind velocity, density, dynamic pressure, IMF B z , and solar wind energetic electrons, as well as > 2 MeV electrons at geosynchronous orbit. Several new results are revealed: (1) there is a strong positive correlation between energetic plasma sheet electrons and solar wind velocity; (2) this correlation is valid throughout the plasma sheet and extends to distances of X GSM =-30 R E ; (3) there is evidence of a weak negative correlation between energetic plasma sheet electrons and solar wind density; (4) energetic plasma sheet electrons are enhanced during times of southward interplanetary magnetic field (IMF); (5) there is no clear correlation between energetic plasma sheet electrons and solar wind electrons of comparable energies; and (6) there is a strong correlation between energetic electrons in the plasma sheet and > 2 MeV electrons at geosynchronous orbit measured 2 days later. In addition, the variability of energetic electron fluxes within the plasma sheet is explored. Interesting events were found using a combination of automated methods and visual inspection. Events are classified into 4 main types: (1) plasma sheet empty of energetic electrons; (2) decreasing plasma sheet energetic electron fluxes; (3) increasing plasma sheet energetic electron fluxes; and (4) sharp

  4. Fragment Characteristics from Photofission of 234U and 238U Induced by 6.0 - 9.0 Mev Bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Göök, A.; Barday, R.; Chernykh, M.; Eckardt, C.; Enders, J.; Neumann-Cosel, P. Von; Poltoratska, Y.; Wagner, M.; Richter, A.; Oberstedt, S.; Hambsch, F.-J.; Oberstedt, A.

    2011-10-01

    As a preparatory experiment for a search for parity violation in photofission, fission of 238U and 234U induced by 6 - 9 MeV bremsstrahlung has been investigated at the superconducting Darmstadt electron linear accelerator S-DALINAC. Using a twin Frisch grid ionization chamber fission fragment energy and mass distributions have been determined by means of the double kinetic energy technique. The experiment was performed in order to test the ionization chamber's performance in a bremsstrahlung environment. Results on the fission fragment characteristics from the 238U(γ,f) reaction are found to be in good agreement with literature values. In addition results on fission fragment mass and energy distributions from the 234U(γ,f) reaction are presented for the first time in this energy region.

  5. Friction wear and auger analysis of iron implanted with 1.5-MeV nitrogen ions

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Jones, W. R., Jr.

    1982-01-01

    The effect of implantation of 1.5-MeV nitrogen ions on the friction and wear characteristics of pure iron sliding against steel was studied in a pin-on disk apparatus. An implantation dose of 5 x 10 to the 17th power ions/sq cm was used. Small reductions in initial and steady-state wear rates were observed for nitrogen-implanted iron riders as compared with unimplanted controls. Auger electron spectroscopy revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 15 at. % at a depth of 8 x 10 to the -7th m. A similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration, thus giving no evidence for diffusion of nitrogen beyond the implanted range.

  6. HRTEM study of track evolution in 120-MeV U irradiated Gd2Ti2O7

    SciTech Connect

    Jozwik Biala, Iwona; Jagielski, Jacek K.; Thome, Lionel; Arey, Bruce W.; Kovarik, Libor; Sattonay, G.; Debelle, A.; Monnet, I.

    2012-09-01

    High resolution Scanning Transmission Electron Microscopy (HRTEM) experiments were performed on Gd2Ti2O7 pyrochlores irradiated with 120-MeV U ions. A judicious choice of irradiation energy, sample preparation (using Focused Ion Beam) and analytical technique (HRTEM) allowed us to visualize the complete evolution of tracks from the surface of samples down to depths exceeding the projected range of irradiating ions. Such features as variation of track diameters, changes in track directions and discontinuous segments of tracks were clearly documented at various depths. By using two different STEM imaging modes: High- and Low-Angle Annular Dark Field imaging (HAADF and LAADF), it was possible to observe the layered structure of tracks composed of an amorphous core surrounded by a strained crystalline envelope.

  7. Microstructure and Nano-Hardness of 10 MeV Cl-Ion Irradiated T91 Steel

    NASA Astrophysics Data System (ADS)

    Hu, Jing; Wang, Xianping; Gao, Yunxia; Zhuang, Zhong; Zhang, Tao; Fang, Qianfeng; Liu, Changsong

    2015-12-01

    Hardening and elemental segregation of T91 martenstic steel irradiated by 10 MeV Cl ions to doses from 0.06 dpa to 0.83 dpa were investigated with the nanoindentation technique and transmission electron microscopy (TEM). The results demonstrated that the irradiation hardening was closely related with irradiation dose. By increasing the dose, the hardness increased rapidly at first from the initial value of 3.15 GPa before irradiation, and then tended to saturate at a value of 3.58 GPa at the highest dose of 0.83 dpa. Combined with TEM observation, the mechanism of hardening was preliminary attributed to the formation of M(Fe,Cr)23C6 carbides induced by the high energy Cl-ion irradiation. supported by National Natural Science Foundation of China (Nos. 11374299, 11375230, 11274309)

  8. 2.6 MeV proton irradiation effects on the surface integrity of depleted UO2

    NASA Astrophysics Data System (ADS)

    Pakarinen, J.; He, L.; Gupta, M.; Gan, J.; Nelson, A.; El-Azab, A.; Allen, T. R.

    2014-01-01

    The effect of low temperature proton irradiation in depleted uranium dioxide was examined as a function of fluence. With 2.6 MeV protons, the fluence limit for preserving a good surface quality was found to be relatively low, about 1.4 and 7.0 × 1017 protons/cm2 for single and poly crystalline samples, respectively. Upon increasing the fluence above this threshold, severe surface flaking and disintegration of samples was observed. Based on scanning electron microscopy (SEM) and X-ray diffraction (XRD) observations the causes of surface failure were associated to high H atomic percent at the peak damage region due to low solubility of H in UO2. The resulting lattice stress is believed to exceed the fracture stress of the crystal at the observed fluencies. The oxygen point defects from the displacement damage may hinder the H diffusion and further increase the lattice stress, especially at the peak damage region.

  9. Production of isotopes and isomers with irradiation of Z = 47–50 targets by 23-MeV bremsstrahlung

    SciTech Connect

    Karamian, S. A.; Carroll, J. J.; Aksenov, N. V.; Albin, Yu. A.; Belov, A. G.; Bozhikov, G. A.; Dmitriev, S. N.; Starodub, G. Ya.

    2015-09-15

    The irradiations of Ag to Sn targets by bremsstrahlung generated with 23-MeV electron beams are performed at the MT-25 microtron. Gamma spectra of the induced activities have been measured and the yields of all detected radionuclides and isomers are carefully measured and analyzed. A regular dependence of yields versus changed reaction threshold is confirmed. Many isomers are detected and the suppression of the production probability is observed with growing product spin. Special peculiarities for the isomer-to-ground state ratios were deduced for the {sup 106m}Ag, {sup 108m}Ag, {sup 113m}In, {sup 115m}In, and {sup 123m}Sn isomers. The production of such nuclides as {sup 108m}Ag, {sup 115m}In, {sup 117g}In, and {sup 113m}Cd is of interest for applications, especially when economic methods are available.

  10. Output Beam Characteristics of 150 MeV Microtron

    NASA Astrophysics Data System (ADS)

    Hori, T.; Tsutsui, H.; Amano, D.; Washio, M.; Yang, J.; Tani, K.

    1997-05-01

    High quality X-ray beam of the pico- to femtosecond pulse width is an indispensable tool for the investigation of various phenomena in the same time scale. Thomson Scattering between electrons and laser beams is considered to be the most promising ("Femtosecond X-ray Pulse Generation Using a Low Emittance Electron Beam and a High Power Laser" M. WASHIO, et al. 7th China-Japan Bilateral Symp. on Radiation Chem., Oct. 28, 1996, Chengdu, China.) to generate that kind of X-ray. For such the purpose, it is inevitable to procure a high quality electron beam of very short and low emittance pulse. We believe that racetrack microtron (RTM) is the best candidate to realize the above interaction because of its compactness which is essential in this experiment. Of course even for the system including RTM, it is obvious that we should adopt the new technology of RF gun with photo cathode in its injection system. We have started as a preliminary work investigating the behavior of conventional RTM which has an 80 keV thermionic gun. Here presented are the experimental results of emittance and enegy spread measurements together with the simulation results of bunch shortening effect of RTM.

  11. Photon and electron collimator effects on electron output and abutting segments in energy modulated electron therapy

    SciTech Connect

    Olofsson, Lennart; Karlsson, Magnus G.; Karlsson, Mikael

    2005-10-15

    In energy modulated electron therapy a large fraction of the segments will be arranged as abutting segments where inhomogeneities in segment matching regions must be kept as small as possible. Furthermore, the output variation between different segments should be minimized and must in all cases be well predicted. For electron therapy with add-on collimators, both the electron MLC (eMLC) and the photon MLC (xMLC) contribute to these effects when an xMLC tracking technique is utilized to reduce the x-ray induced leakage. Two add-on electron collimator geometries have been analyzed using Monte Carlo simulations: One isocentric eMLC geometry with an isocentric clearance of 35 cm and air or helium in the treatment head, and one conventional proximity geometry with a clearance of 5 cm and air in the treatment head. The electron fluence output for 22.5 MeV electrons is not significantly affected by the xMLC if the shielding margins are larger than 2-3 cm. For small field sizes and 9.6 MeV electrons, the isocentric design with helium in the treatment head or shielding margins larger than 3 cm is needed to avoid a reduced electron output. Dose inhomogeneity in the matching region of electron segments is, in general, small when collimator positions are adjusted to account for divergence in the field. The effect of xMLC tracking on the electron output can be made negligible while still obtaining a substantially reduced x-ray leakage contribution. Collimator scattering effects do not interfere significantly when abutting beam techniques are properly applied.

  12. /sup 24/Mg yrast sequence up to 30 MeV excitation

    SciTech Connect

    Szanto de Toledo, A.; Cormier, T.M.; Coimbra, M.M.; Filho, N.C.; Stwertka, P.M.; Nicolis, N.G.

    1984-11-01

    Highly excited states observed in the /sup 12/C(/sup 16/O,..cap alpha..)/sup 24/Mg reaction are analyzed within the statistical model. Evidence that the E( = 28.21, 33.34, and 38.22 MeV states correspond to high spin states is found. The /sup 24/Mg yrast line can be identified up to the 12/sup +/ state located at 28.21 MeV excitation energy.

  13. Measurement and evaluation of selected 14-MeV neutron cross sections for fusion

    SciTech Connect

    Meadows, J.W.; Smith, D.L.; Cox, S.A.

    1985-01-01

    Experimental neutron-activation cross-section data in the vicinity of 14 MeV are evaluated for several reactions of fusion-related interest using a least-squares method. New experimental measurements are performed at 14.7 MeV for all of these considered reactions and for some commonly-used standard reactions as well. Comparison is made between measured and evaluated results.

  14. First experimental results from 2MeV proton tandem accelerator for neutron productiona)

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, A.; Belchenko, Yu.; Burdakov, A.; Davydenko, V.; Ivanov, A.; Khilchenko, A.; Konstantinov, S.; Krivenko, A.; Kuznetsov, A.; Mekler, K.; Sanin, A.; Shirokov, V.; Sorokin, I.; Sulyaev, Yu.; Tiunov, M.

    2008-02-01

    A 2MeV proton tandem accelerator with vacuum insulation was developed and first experiments are carried out in the Budker Institute of Nuclear Physics (Novosibirsk). The accelerator is designed for neutron production via reaction Li7(p,n)Be7 for the boron neutron-capture therapy of the brain tumors, and for explosive detection based on 9.1724MeV resonance gamma, which are produced via reaction C13(p,γ)N14, absorption in nitrogen.

  15. Numerical Simulation of the Medical Linear Accelerator Electron Beams Absorption by ABS-Plastic doped with Metal

    NASA Astrophysics Data System (ADS)

    Stuchebrov, S. G.; Miloichikova, I. A.; Krasnykh, A. A.

    2016-07-01

    In this paper the numerical simulation results of the dose spatial distribution of the medical electron beams in ABS-plastic doped with different concentrations of lead and zinc are shown. The dependences of the test material density on the lead and zinc mass concentrations are illustrated. The depth dose distributions of the medical electron beams in the modified ABS-plastic for three energies 6 MeV, 12 MeV and 20 MeV are tested. The electron beam shapes in the transverse plane in ABS-plastic doped with different concentrations of lead and zinc are presented.

  16. Electron photon verification calculations using MCNP4B

    SciTech Connect

    Gierga, D.P.; Adams, K.J.

    1998-07-01

    MCNP4B was released in February 1997 with significant enhancements to electron/photon transport methods. These enhancements have been verified against a wide range of published electron/photon experiments, spanning high energy bremsstrahlung production to electron transmission and reflection. Three sets of bremsstrahlung experiments were simulated. The first verification calculations for bremsstrahlung production used the experimental results in Faddegon for 15 MeV electrons incident on lead, aluminum, and beryllium targets. The calculated integrated bremsstrahlung yields, the bremsstrahlung energy spectra, and the mean energy of the bremsstrahlung beam were compared with experiment. The impact of several MCNP tally options and physics parameters was explored in detail. The second was the experiment of O`Dell which measured the bremsstrahlung spectra from 10 and 20.9 MeV electrons incident on a gold/tungsten target. The final set was a comparison of relative experimental spectra with calculated results for 9.66 MeV electrons incident on tungsten based on the experiment of Starfelt and Koch. The transmission experiments of Ebert were also studied, including comparisons of transmission coefficients for 10.2 MeV electrons incident on carbon, silver, and uranium foils. The agreement between experiment and simulation was usually within two standard deviations of the experimental and calculational errors.

  17. Determination of Neutron Spectrum by the Dosimetry Foil Method up to 37 Mev

    NASA Astrophysics Data System (ADS)

    Simakov, S. P.; Bém, P.; Burjan, V.; Fischer, U.; Forrest, R. A.; Götz, M.; Honusek, M.; Kroha, V.; Novàk, J.; Šimečková, E.

    2009-08-01

    The dosimetry activation foil technique was used for the determination of a white neutron spectrum at the U120M cyclotron facility of NPI/Řež. The neutrons were produced by 37 MeV protons slowing down in the thick heavy water target and have an energy distribution extending up to 37 MeV. To cover the whole energy range a set of 10 foils Al, Ti, Fe, Co, Ni, Y, Nb, In, Lu, and Au was used. The γ-rays from the decaying nuclei produced in 26 activation reactions were detected. The cross sections for these reaction were chosen from European Activation File EAF-2007 (up to 55 MeV) after intercomparison with the dosimetry cross section library IRDF-2002 which represents the cross section only up to 20 MeV and other high energy libraries. For the spectrum determination the SAND-II code was used after it had been modified to input dosimetry cross sections above 20 MeV in an arbitrary group structure. The guessed neutron spectrum which is needed to start an adjustment procedure was combined from those measured and calculated by the MCNPX code. The uncertainty of the adjusted neutron spectrum was estimated using the uncertainties of measured specific γ-activities induced in nuclides and dosimetry cross sections. It is less than 10% in the energy range below 25 MeV, the sensitivity domain of the most dosimetry reactions, but increases above this energy.

  18. Measurement of the {sup 241}Am(n,2n) reaction cross section from 7.6 MeV to 14.5 MeV

    SciTech Connect

    Tonchev, A. P.; Crowell, A. S.; Fallin, B.; Howell, C. R.; Hutcheson, A.; Tornow, W.; Angell, C. T.; Boswell, M.; Hammond, S.; Karwowski, H. J.; Kelley, J. H.; Pedroni, R. S.; Becker, J. A.; Dashdorj, D.; Kenneally, J.; Macri, R. A.; Stoyer, M. A.; Wu, C. Y.; Bond, E.; Chadwick, M. B.

    2008-05-15

    The (n,2n) cross section of the radioactive isotope {sup 241}Am (T{sub 1/2}=432.6 y) has been measured in the incident neutron energy range from 7.6 to 14.5 MeV in steps of a few MeV using the activation technique. Monoenergetic neutron beams were produced via the {sup 2}H(d,n){sup 3}He reaction by bombarding a pressurized deuterium gas cell with an energetic deuteron beam at the TUNL 10-MV Van de Graaff accelerator facility. The induced {gamma}-ray activity of {sup 240}Am was measured with high-resolution HPGe detectors. The cross section was determined relative to Al, Ni, and Au neutron activation monitor foils, measured in the same geometry. Good agreement is obtained with previous measurements at around 9 and 14 MeV, whereas for a large discrepancy is observed when our data are compared to those reported by Perdikakis et al. near 11 MeV. Very good agreement is found with the END-B/VII evaluation, whereas the JENDL-3.3 evaluation is in fair agreement with our data.

  19. Photodisintegration of /sup 3/H and /sup 3/He. [Threshold to 25 MeV

    SciTech Connect

    Faul, D.D.

    1980-09-01

    The photoneutron cross sections for /sup 3/H and /sup 3/He have been measured from threshold to approx. 25 MeV with monoenergetic photons from the annihilation in flight of fast positrons at the LLL Electron-Positron Linear Accelerator facility. These reactions include the two-body breakup of /sup 3/H and the three-body breakup of both /sup 3/H and /sup 3/He; these measurements for /sup 3/H are the first to span the energy region across the peaks of the cross sections. An efficient BF/sub 3/-tube-and-paraffin neutron detector and high-pressure gaseous samples of several moles each (the activity of the /sup 3/H sample was approx. 200,000 Ci) were employed in these measurements. Measurements on /sup 16/O and /sup 2/H also were performed to verify the absolute cross-section scale. The results, when compared with each other and with results for the two-body breakup cross section for /sup 3/He from the literature, show that the two-body breakup cross sections for /sup 3/H and /sup 3/He have nearly the same shape, but the one for /sup 3/He lies lower in magnitude; the three-body breakup cross section for /sup 3/He lies higher in magnitude and is broader in the peak region and also rises less sharply from threshold than that for /sup 3/H; and these measured differences between the cross sections for the breakup modes largely compensate in their sum, so that the total photon absorption cross sections for /sup 3/H and /sup 3/He are nearly the same in both size and shape at energies near and above their peaks. Theoretical results from the literature disagree with the experimental results to a certain extent over the entire photon-energy region for which the photoneutron cross sections were measured. 50 figures, 7 tables.

  20. Low dose irradiation creep of pure nickel. [17 or 15 MeV deuterons

    SciTech Connect

    Henager, C.H. Jr.

    1984-10-01

    A detailed climb-controlled glide model of low dose irradiation creep has been developed to rationalize irradiation creep data of pure nickel irradiated in a light ion irradiation creep apparatus. Experimental irradiation creep data were obtained to study the effects of initial microstructure and stress on low dose irradiation creep in pure nickel. Pure nickel specimens (99.992% Ni), with three different microstructures, were irradiated with 17 or 15 MeV deuterons at 473 K and stresses ranging from 0.35 to 0.9 of the unirradiated yield stress. Transmission electron microscopy revealed that the microstructure following irradiation to 0.05 dpa consisted of a high density of small dislocation loops, some small voids and network dislocations. The creep model predicted creep rates proportional to the mobile dislocation density and a comparison of experimental irradiation creep rates as a function of homologous stress revealed a dependence on initial microstructure of the magnitude predicted by the measured dislocation densities. The three microstructures that were irradiated consisted of 85% and 25% cold-worked Ni specimens and well-annealed Ni specimens. A weak stress dependence of irradiation creep was observed in 85% cold-worked Ni in agreement with experimental determinations of the stress dependence of irradiation creep by others. The weak stress dependence was shown to be a consequence of the stress independence of the dislocation climb velocity and the weak stress dependence of the barrier removal process. The irradiation creep rate was observed to be proportional to the applied stress. This linear stress dependence was suggested to be due to the stress dependence of the mobile dislocation density. 101 references, 27 figures, 11 tables.

  1. Structural and optical studies of 100 MeV Au irradiated thin films of tin oxide

    NASA Astrophysics Data System (ADS)

    Jaiswal, Manoj Kumar; Kanjilal, D.; Kumar, Rajesh

    2013-11-01

    Thin films of tin(IV) oxide (SnO2) of 100 nm thickness were grown on silicon (1 0 0) matrices by electron beam evaporation deposition technique under high vacuum. The thicknesses of these films were monitored by piezo-sensor attached to the deposition chamber. Nanocrystallinity is achieved in these thin films by 100 MeV Au8+ using 1 pnA current at normal incidence with ion fluences varying from 1 × 1011 ions/cm2 to 5 × 1013 ions/cm2. Swift Heavy Ion beam irradiation was carried out by using 15 UD Pelletron Accelerator at IUAC, New Delhi, India. Optical studies of pristine and ion irradiated thin films were characterized by UV-Visible spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy. Prominent peak at 610 cm-1 in FTIR spectrum confirmed the O-Sn-O bonding of tin(IV) oxide. For Surface topographical studies and grain size calculations, these films were characterized by Atomic Force Microscope (AFM) using Nanoscope III-A. Crystallinity and phase transformation due to irradiation of pristine and irradiated films were characterized by Glancing Angle X-ray Diffraction (GAXRD) using Brucker-D8 advance model. GAXRD results show improvement in crystallinity and phase transformation due to swift heavy ion irradiation. Grain size distribution was verified by AFM and GAXRD results. Swift heavy ion induced modifications in thin films of SnO2 were confirmed by the presence of prominent peaks at 2θ values of 30.65°, 32.045°, 43.94°, 44.96° and 52.36° in GAXRD spectrum.

  2. Electronic properties of CVD and synthetic diamond

    NASA Astrophysics Data System (ADS)

    Nebel, C. E.; Müautnz, J.; Stutzmann, M.; Zachai, R.; Güautttler, H.

    1997-04-01

    Transport and contact properties of synthetic IIb- and intrinsic chemical vapor deposition (CVD) -diamond films are discussed. The samples have been investigated by time-of-flight and transient photoconductivity experiments using Cr/Au contacts. A hole depletion layer at the Cr/Au-IIb-diamond interface and an electron depletion layer at the Cr/Au-CVD-diamond interface is detected. The data indicate that our normally undoped CVD-diamond films are n-type semiconductors. In IIb diamond the mobilities of electrons and holes have been measured, while in CVD diamond no carrier transit can be detected due to the short Schubweg less than or equal to 1 μm. Two trap levels located approximately 190 meV below the conduction band and 670 meV above the valence band are deduced. Electron spin resonance experiments demonstrate that these CVD films are highly defective, containing about 1018 cm-3 carbon related defects (g=2.0029).

  3. Acceleration of Hydrogen Ions up to 30 MeV and Generation of 3 × 1012 Neutrons in Megaampere Deuterium Gas-Puff Z-Pinch

    NASA Astrophysics Data System (ADS)

    Klir, D.; Cikhardt, J.; Kravarik, J.; Kubes, P.; Rezac, K.; Sila, O.; Shishlov, A.; Cherdizov, R.; Fursov, F.; Kokshenev, V.; Kovalchuk, B.; Kurmaev, N.; Labetsky, A.; Ratakhin, N.; Orcikova, H.; Turek, K.

    2013-10-01

    Fusion neutrons were produced with a deuterium gas-puff z-pinch on the GIT-12 generator at the Institute of High Current Electronics in Tomsk. The peak neutron yield from DD reactions reached Yn = (2 . 9 +/- 0 . 3) ×1012 at 100 μg/cm linear mass density of deuterium, 700 ns implosion time and 2.7 MA current. Such a neutron yield means that the scaling law of deuterium z-pinches Yn ~I4 was extended to 3 MA currents. The further increase of neutron yields up to (3 . 7 +/- 0 . 4) ×1012 was achieved by placing a deuterated polyethylene catcher onto the axis. Maximum neutron energies of 15 and 22 MeV were observed by radial and axial nToF detectors, respectively. A stack of CR-39 track detectors showed up to 40 MeV deuterons (or 30 MeV protons) on the z-pinch axis. Since the energy input into plasmas was 70 kJ, the number of DD neutrons per one joule of stored plasma energy exceeded the value of 5 ×107 . This value implies that deuterium gas-puff z-pinches belong to the most efficient plasma-based sources of DD neutrons. This work was partially supported by the GACR grant No. P205/12/0454 and by the RFBR research project No. 13-08-00479-a.

  4. Charge State Dependence of M-Shell X-Ray Production in HOLMIUM-67 by 2-12 Mev Carbon Ions

    NASA Astrophysics Data System (ADS)

    Sun, Hsueh-Li.

    Charge state dependence of M-shell x-ray production cross sections of _{67}Ho bombarded by 2-12 MeV carbon ions with and without K-vacancies are reported. The experiments were performed using an NEC 9SDH-2 tandem accelerator at the Ion Beam Modification and Analysis Laboratory of University of North Texas. The high charge state carbon ions were produced by a post-accelerator gas stripper. The ultra-clean holmium targets were used in ion-atom collision to generate M-shell x rays at energies from 1.05 to 1.58 keV. The x-ray measurements were made with a windowless Si(Li) x-ray detector that was calibrated by radioative sources, particle induced x-ray emission (PIXE), and the atomic field bremsstrahlung (AFB) techniques. Experimental results are compared to the predictions of the first Born and ECPSSR theories using single-hole fluorescence yield. The theories include two ionization mechanisms, direct ionization (DI) of the target electron to the continuum and electron capture (EC) from the target to the projectile. The first Born theory describes the DI by plane wave Born approximation (PWBA) and electron capture (EC) by Oppenheimer-Brinkman-Kramers treatment of Nikolaev (OBKN). The ECPSSR theory accounts for the energy loss (E) and Coulomb deflection (C) of the projectile while passing the target atom as well as the perturbed stationary states (PSS) and the relativistic effects of the target electron during interaction with the projectile. The electron capture cross sections can be extracted from the charge state dependence of the x-ray production cross section. The first Born theory overpredicts all the data of the total M-shell x-ray production cross sections and the electron capture cross sections. The ECPSSR theory gives good agreement to the total M-shell x-ray production cross section for 6-12 MeV carbon ions with charge state 3+ and 4+, but overpredicts the result of charge state 5+ and 6+ and all of the data at energies 2 to 4 MeV. The ECPSSR theory also

  5. OPTICS OF A TWO-PASS ERL AS AN ELECTRON SOURCE FOR A NON-MAGNETIZED RHIC-II ELECTRON COOLER.

    SciTech Connect

    KAYRAN,D.

    2007-06-25

    Non-magnetized electron cooling of RHIC requires an electron beam energy of 54.3 MeV, electron charge per bunch of 5 nC, normalized rms beam emittance of 4 mm-mrad, and rms energy spread of 4e-04 [I]. In this paper we describe a lattice of a two-pass SRF energy recovery linac (ERL) and results of a PARMELA simulation that provides electron beam parameters satisfying RHIC electron cooling requirements.

  6. Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

    SciTech Connect

    Li, W.; Thorne, R. M.; Bortnik, J.; Baker, D. N.; Reeves, G. D.; Kanekal, S. G.; Spence, H. E.; Green, J. C.

    2015-09-07

    In this study by determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations (>1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly comparing efficient and inefficient acceleration events, we clearly show that prolonged southward Bz, high solar wind speed, and low dynamic pressure are critical for electron acceleration to >1 MeV energies in the heart of the outer radiation belt. We also evaluate chorus wave evolution using the superposed epoch analysis for the identified efficient and inefficient acceleration events and find that chorus wave intensity is much stronger and lasts longer during efficient electron acceleration events, supporting the scenario that chorus waves play a key role in MeV electron acceleration.

  7. Ultrashort megaelectronvolt positron beam generation based on laser-accelerated electrons

    NASA Astrophysics Data System (ADS)

    Xu, Tongjun; Shen, Baifei; Xu, Jiancai; Li, Shun; Yu, Yong; Li, Jinfeng; Lu, Xiaoming; Wang, Cheng; Wang, Xinliang; Liang, Xiaoyan; Leng, Yuxin; Li, Ruxin; Xu, Zhizhan

    2016-03-01

    Experimental generation of ultrashort MeV positron beams with high intensity and high density using a compact laser-driven setup is reported. A high-density gas jet is employed experimentally to generate MeV electrons with high charge; thus, a charge-neutralized MeV positron beam with high density is obtained during laser-accelerated electrons irradiating high-Z solid targets. It is a novel electron-positron source for the study of laboratory astrophysics. Meanwhile, the MeV positron beam is pulsed with an ultrashort duration of tens of femtoseconds and has a high peak intensity of 7.8 × 1021 s-1, thus allows specific studies of fast kinetics in millimeter-thick materials with a high time resolution and exhibits potential for applications in positron annihilation spectroscopy.

  8. s-wave threshold in electron attachment - Observations and cross sections in CCl4 and SF6 at ultralow electron energies

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Alajajian, S. H.

    1985-01-01

    The threshold photoionization method was used to study low-energy electron attachment phenomena in and cross sections of CCl4 and SF6 compounds, which have applications in the design of gaseous dielectrics and diffuse discharge opening switches. Measurements were made at electron energies from below threshold to 140 meV at resolutions of 6 and 8 meV. A narrow resolution-limited structure was observed in electron attachment to CCl4 and SF6 at electron energies below 10 meV, which is attributed to the divergence of the attachment cross section in the limit epsilon, l approaches zero. The results are compared with experimental collisional-ionization results, electron-swarm unfolded cross sections, and earlier threshold photoionization data.

  9. Complete identification of states in 208Pb below Ex=6.2 MeV

    NASA Astrophysics Data System (ADS)

    Heusler, A.; Jolos, R. V.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.; von Brentano, P.

    2016-05-01

    The Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium of the Ludwig-Maximilians-Universität München and the Technische Universität München (Garching, Germany), was used to study the 208Pb(p ,p' ) , 206,207,208Pb (d,p), and 208Pb(d ,d' ) reactions. One hundred fifty-one states at Ex<6.20 MeV in 208Pb are identified and spin and parity assigned. Four states are newly identified and new spins and/or parities are assigned to 25 states. Tentative spin assignments are done to five states at 5.90 MeV . Nearly 50 levels below Ex=6.20 MeV listed by the Nuclear Data Sheets as of 2007 are recognized to be nonexistent or doubly placed. The schematic shell model describing one-particle-one-hole configurations without residual interaction is extended by including two-particle-two-hole configurations. The number of configurations thus predicted at Ex<6.20 MeV nearly agrees with the number of states identified. Several states with dominant two-particle-two-hole configurations are identified. New isobaric analog resonances in 209Bi with two-particle-one-hole structure are discovered at Eres=17.6 MeV . The excitation energies of 70 states with unnatural parity at Ex<6.20 MeV are found to agree within about 200 keV with one-particle-one-hole configurations predicted by the extended schematic shell model. In contrast, the excitation energies of about 20 natural parity states are more than 0.5 MeV lower than predicted, demonstrating the residual interaction among the configurations to be much larger for natural parity than for unnatural parity.

  10. MeV Science with the Advanced Energetic Pair Telescope (AdEPT), a High Sensitivity Medium-Energy Gamma-Ray Polarimeter

    NASA Astrophysics Data System (ADS)

    Venters, Tonia M.; Hunter, Stanley D.; De Nolfo, Georgia; Hanu, Andrei R.; Krizmanic, John F.; Stecker, Floyd W.; Timokhin, Andrey

    2016-04-01

    Many high-energy astrophysical phenomena exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares below ~200 MeV. However, while significant progress in gamma-rays has been made by instruments such as Fermi and AGILE, a significant sensitivity gap remains in the medium-energy regime (0.75 - 200 MeV) that has been explored only by COMPTEL and EGRET on CGRO. Tapping into this unexplored regime requires development of a telescope with significant improvement in sensitivity. Our mission concept, covering ~5 to ~200 MeV, is the Advanced Energetic Pair Telescope (AdEPT). The AdEPT telescope will achieve angular resolution of ~0.6 deg at 70 MeV, similar to the angular resolution of Fermi/LAT at ~1 GeV that brought tremendous success in identifying new sources. AdEPT will also provide unprecedented polarization sensitivity, ~1% for a 1 Crab source. The enabling technology for AdEPT is the Three-Dimensional Track Imager (3-DTI) a low-density, large volume, gas time-projection chamber with a 2-dimensional readout. The 3-DTI provides high-resolution three-dimensional electron tracking with minimal Coulomb scattering that is essential to achieve high angular resolution and polarization sensitivity. We describe the design, fabrication, and performance of the 3-DTI detector, describe the development of a 50x50x100 cm3 AdEPT prototype, and highlight a few of the key science questions that AdEPT will address.

  11. The use of electron beams for pasteurization of meats

    SciTech Connect

    Prestwich, K.R.; Kaye, R.J.; Turman, B.N.; Neau, E.L.

    1994-12-01

    Electron beam accelerators can be used for electronic pasteurization of meat products by: (1) using the electrons directly impacting the products, or (2) optimizing the conversion of electron energy to x-rays and treating the product with these x-rays. The choice of process depends on the configuration of the product when it is treated. For electron treatment, ten million electron volt (MeV) kinetic energy is the maximum allowed by international agreement. The depth of penetration of electrons with that energy into a product with density of meat is about five centimeters (cm). Two-sided treatment can be done on products up to 10 cm thick with a two-to-one ratio between minimum and maximum dose. Ground beef patties are about 1.25 cm (0.5 inch thick). Beams with 2.5 MeV electron energy could be used to treat these products. Our calculations show that maximum to minimum dose ratios less than 1.2 can be achieved with this energy if the transverse beam energy is small. If the product thickness is greater than 10 cm, x-rays can provide the needed dose uniformity. Uniform doses can be supplied for pallets with dimensions greater than 1.2 m on each side using x-rays from a 5 MeV electron beam. The efficiency of converting the electron beam to x-rays and configurations to achieve dose uniformity are discussed.

  12. The source of multi spectral energy of solar energetic electron

    SciTech Connect

    Herdiwijaya, Dhani

    2015-04-16

    We study the solar energetic electron distribution obtained from ACE and GOES satellites which have different altitudes and electron spectral energy during the year 1997 to 2011. The electron spectral energies were 0.038–0.315 MeV from EPAM instrument onboard ACE satellite and >2 MeV from GOES satellite. We found that the low electron energy has no correlation with high energy. In spite of we have corrected to the altitude differences. It implied that they originated from time dependent events with different sources and physical processes at the solar atmosphere. The sources of multi spectral energetic electron were related to flare and CME phenomena. However, we also found that high energetic electron comes from coronal hole.

  13. Measurement of isomeric ratios for 89g,mZr, 91g,mMo, and 97g,mNb in the bremsstrahlung end-point energies of 16 and 45-70 MeV

    NASA Astrophysics Data System (ADS)

    Naik, H.; Kim, G. N.; Schwengner, R.; Kim, K.; Zaman, M.; Yang, S. C.; Shin, S. G.; Kye, Y.-U.; Massarczyk, R.; John, R.; Junghans, A.; Wagner, A.; Goswami, A.; Cho, M.-H.

    2016-03-01

    The independent isomeric yield ratios of 89g,mZr from the natZr(γ,xn) reactions and those of 91g, mMo and 97g,mNb from the natMo(γ,x) reactions with the bremsstrahlung end-point energy of 45-70 MeV were determined by an off-line γ-ray spectrometric technique using the 100 MeV electron linac at the Pohang Accelerator Laboratory, Korea. The isomeric yield ratios of 89g,mZr and 97g,mNb from the natZr(γ, xn) and natMo(γ,x) reactions at the bremsstrahlung end-point energy of 16MeV were also determined by the same technique using the 20MeV electron linac at Helmholtz-Zentrum Dresden-Rossendorf, Germany. The measured isomeric yield ratios of 89g,mZr, 91g,mMo, and 97g,mNb were compared with literature data to examine the role of the Giant Dipole Resonance (GDR). The isomeric yield ratios of the 89g,mZr, 91g,mMo, and 97g,mNb from the above reactions were also calculated by using the computer code TALYS 1.6 and compared with the experimental data to examine the validity of the theoretical model for independent isomeric yield ratio calculations.

  14. Measurements of the UV and VUV transmission of optical materials during high energy electron irradiation

    NASA Technical Reports Server (NTRS)

    Palma, G. E.

    1972-01-01

    An experimental program was conducted in which the optical transmission of several transparent materials was measured during high energy electron irradiation. These experiments were conducted using the Dynamitron electron accelerator as a continuous source of 1.5 MeV electrons and the LINAC electron accelerator as a pulsed source of 5-7 MeV electrons. The experimental program consisted of three major portions. The first portion, the optical transmission of fused silica, BeO, MgF2, and LiF was measured at vacuum ultraviolet wavelengths in the range 1550-2000 A during ambient temperature, 1.5 MeV electron irradiation at ionizing dose rates to 0.5 Mrad/sec. In the second portion of the program, the optical transmission of fused silica and BeO was measured in the range 2000-3000 A during high dose rate, elevated temperature 1.5 MeV electron irradiation. In particular, accurate measurements of the optical transmission were made at ionizing dose rates as high as 10 Mrad/sec. In the final portion of the program, the optical transmission of fused silica and BeO was measured in the wavelength range 2000-3000 A during pulsed 5 and 7 MeV electron irradiation from the LINAC accelerator. The maximum time averaged ionizing dose rate was limited to 0.75 Mrad/sec due to accelerator limitations.

  15. Changes of structure and electrical conductivity of multi-walled carbon nanotubes film caused by 3 MeV proton irradiation

    NASA Astrophysics Data System (ADS)

    Yang, Jianqun; Li, Xingji; Liu, Chaoming; Ma, Guoliang

    2015-01-01

    The effects of 3 MeV proton irradiation for fluences of 3.5 × 1010 cm-2 to 3.1 × 1012 cm-2 on structure and electrical conductivity of multi-walled carbon nanotubes (MWCNTs) film were investigated. The pristine and the irradiated MWCNTs films were characterized using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and electron paramagnetic resonance (EPR) spectroscopy in order to investigate the effects of irradiation on their structure. Electrical conductivity of the MWCNTs films was characterized before and after irradiation. SEM analysis reveals that the proton irradiation for the high fluence (more than 3.6 × 1011 cm-2) leads to evident changes in morphology of the MWCNTs film, such as forming uneven film surface, curve, shrinkage and fragmentation of nanotubes. Based on Raman, XPS, FTIR and EA analyses, it is confirmed that the 3 MeV protons with high fluence (more than 3.6 × 1011 cm-2) can damage the structure of the MWCNTs, including increase of the disorder and the formation of functional groups. EPR spectroscopy shows that the electrons delocalized over carbon nanotubes increase with increasing irradiation fluence, implying that the MWCNTs film might be sensitive to ionizing radiation to some extent. With increasing the irradiation fluence, the electrical conductivity of the MWCNTs film decreases due to the structural and morphological damage.

  16. DESIGN OF A 250 MeV, X-BAND PHOTOINJECTOR LINAC FOR A PRECISION COMPTON-SCATTERING BASED GAMMA-RAY SOURCE

    SciTech Connect

    Anderson, S G; Albert, F; Gibson, D J; McNabb, D; Messerly, M; Rusnak, B; Shverdin, M; Hartemann, F V; Siders, C W; Barty, C J; Tantawi, S; Vlieks, A

    2009-05-07

    We present a compact, X-band, high-brightness accelerator design suitable for driving a precision gamma-ray source. Future applications of gamma-rays generated by Compton-scattering of laser and relativistic electron beams place stringent demands on the brightness and stability of the incident electron beam. This design identifies the beam parameters required for gamma-ray production, including position, and pointing stability. The design uses an emittance compensated, 11.4 GHz photo-gun and linac to generate 400 pC, 1-2 mm-mrad electron bunches at up to 250 MeV and 120 Hz repetition rate. The effects of jitter in the RF power system are analyzed as well as structure and optic misalignments. Finally, strategies for the mitigation of on-axis Bremsstrahlung noise are discussed.

  17. Linear photon upconversion of 400 meV in an AlGaInP/GaInP quantum well heterostructure to visible light at room temperature

    NASA Astrophysics Data System (ADS)

    Olson, M. R.; Russell, K. J.; Narayanamurti, V.; Olson, J. M.; Appelbaum, Ian

    2006-04-01

    We linearly up convert photons from 820to650nm, an energy change of ˜400meV, using a AlGaInP /GaInP quantum well heterostructure. Current and luminescence-voltage measurements are presented at temperatures from 6to300K. Photoexcited electrons are injected into the semiconductor from the Au Schottky and a forward bias across the p+-i-n heterostructure drifts electrons into the GaInP quantum well. Holes diffuse from the heavily doped substrate and radiatively recombine, emitting ˜650nm light. Linear upconversion is verified by injecting hot electrons with a solid-state tunnel junction. This device encourages other technologies, including night-vision aids and thermal energy converters.

  18. An Inverse Free-Electron-Laser accelerator

    SciTech Connect

    Fisher, A.S.; Gallardo, J.C.; van Steenbergen, A.; Ulc, S.; Woodle, M.; Sandweiss, J.; Fang, Jyan-Min

    1993-08-01

    Recent work at BNL on electron acceleration using the Inverse Free-Electron Laser (IFEL) has considered a low-energy, high-gradient, multi-stage linear accelerator. Experiments are planned at BNL`s Accelerator Test Facility using its 50-MeV linac and 100-GW CO{sub 2} laser. We have built and tested a fast-excitation wiggler magnet with constant field, tapered period, and overall length of 47 cm. Vanadium-Permendur ferromagnetic laminations are stacked in alternation with copper, eddy-current-induced, field reflectors to achieve a 1.4-T peak field with a 4-mm gap and a typical period of 3 cm. The laser beam will pass through the wiggler in a low-loss, dielectric-coated stainless-steel, rectangular waveguide. The attenuation and transverse mode has been measured in waveguide sections of various lengths, with and without the dielectric. Results of 1-D and 3-D IFEL simulations, including wiggler errors, will be presented for several cases: the initial, single-module experiment with {Delta}E = 39 MeV, a four-module design giving {Delta}E = 100 MeV in a total length of 2 m, and an eight-module IFEL with {Delta}E = 210 MeV.

  19. K-MM radiative Auger effect in solid Ca, Ti and Cr targets after ionization with 0.7-1.5 MeV protons

    NASA Astrophysics Data System (ADS)

    Budnar, M.; Mühleisen, A.; Hribar, M.; Janžekovič, H.; Ravnikar, M.; Šmit, Ž.; Žitnik, M.

    1992-03-01

    Radiative Auger (RAE) X-ray spectra were measured for the first time on Ca, Cr, and Ti targets after ionization by 0.7-1.5 MeV protons. The energies of the RAE X-ray transitions were compared with the energies obtained from the Auger transitions. The RAE intensities relative to the diagram K β13 line were deduced and compared with the available data from X-ray fluorescence and electron capture ionization. The relative yields obtained for Ca, Ti, and Cr were (3.14 ± 0.47), (2.44 ± 0.37) and (2.91 ± 0.58)%, respectively.

  20. The low energy particle detector sled (~30 keV-3.2 MeV) and its performance on the phobos mission to mars and its moons

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S.; Afonin, V. V.; Gringauz, K. I.; Keppler, E.; Kirsch, E.; Richter, A.; Witte, M.; O'Sullivan, D.; Thompson, A.; Somogyi, A. J.; Szabo, L.; Varga, A.

    1990-05-01

    A low energy particle detector system (SLED) is described which was designed to measure the flux densities of electrons and ions in the energy range from ~30 keV to a few MeV in (a) the varying solar aspect angles and temperatures pertaining during the Cruise Phase of the Phobos Mission and (b) in the low temperature environment (reaching -25° C) pertaining during Mars Encounter. Representative data illustrating the excellent functioning of SLED during both phases of the mission are presented.