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Sample records for accelerator neutron production

  1. PRODUCTION AND APPLICATIONS OF NEUTRONS USING PARTICLE ACCELERATORS

    SciTech Connect

    David L. Chichester

    2009-11-01

    Advances in neutron science have gone hand in hand with the development and of particle accelerators from the beginning of both fields of study. Early accelerator systems were developed simply to produce neutrons, allowing scientists to study their properties and how neutrons interact in matter, but people quickly realized that more tangible uses existed too. Today the diversity of applications for industrial accelerator-based neutron sources is high and so to is the actual number of instruments in daily use is high, and they serve important roles in the fields where they're used. This chapter presents a technical introduction to the different ways particle accelerators are used to produce neutrons, an historical overview of the early development of neutron-producing particle accelerators, a description of some current industrial accelerator systems, narratives of the fields where neutron-producing particle accelerators are used today, and comments on future trends in the industrial uses of neutron producing particle accelerators.

  2. Production and Applications of Neutrons Using Particle Accelerators

    NASA Astrophysics Data System (ADS)

    Chichester, David L.

    2012-06-01

    Advances in neutron science have gone hand in hand with the development of particle accelerators from the beginning of both fields. Early accelerator systems were developed simply to produce neutrons, allowing scientists to study their properties and interactions with matter, but people quickly realized that more tangible uses existed for them. Today, these systems are in use in such diverse applications as mineral assaying, oil well logging, radiography, and explosive detection to name a few. This chapter presents a technical introduction to the different ways particle accelerators are used to produce neutrons, an historical overview of the development of neutron-producing particle accelerators, a description of current industrial accelerator systems, narratives of the industrial fields where neutron-producing particle accelerators are used today, and comments on future trends.

  3. Linear induction accelerators for fusion and neutron production

    SciTech Connect

    Barletta, W.A. |

    1993-08-01

    Linear induction accelerators (LIA) with pulsed power drives can produce high energy, intense beams or electrons, protons, or heavy ions with megawatts of average power. The continuing development of highly reliable LIA components permits the use such accelerators as cost-effective beam sources to drive fusion pellets with heavy ions, to produce intense neutron fluxes using proton beams, and to generate with electrons microwave power to drive magnetic fusion reactors and high gradient, rf-linacs.

  4. Estimation of thermal neutron fluences in the concrete of proton accelerator facilities from 36Cl production

    NASA Astrophysics Data System (ADS)

    Bessho, K.; Matsumura, H.; Miura, T.; Wang, Q.; Masumoto, K.; Hagura, H.; Nagashima, Y.; Seki, R.; Takahashi, T.; Sasa, K.; Sueki, K.; Matsuhiro, T.; Tosaki, Y.

    2007-06-01

    The thermal neutron fluence that poured into the shielding concrete of proton accelerator facilities was estimated from the in situ production of 36Cl. The thermal neutron fluences at concrete surfaces during 10-30 years of operation were in the range of 1012-1014 n/cm2. The maxima in thermal neutron fluences were observed at ≈5-15 cm in the depths analyzed for 36Cl/35Cl by AMS. These characteristics imply that thermalization of neutrons occurred inside the concrete. Compared to the several tens of MeV cyclotrons, secondary neutrons penetrate deeper into the concrete at the high-energy accelerators possessing acceleration energies of 400 MeV and 12 GeV. The attenuation length of neutrons reflects the energy spectra of secondary neutrons emitted by the nuclear reaction at the beam-loss points. Increasing the energy of secondary neutrons shifts the maximum in the thermal neutron fluences to deeper positions. The data obtained in this study will be useful for the radioactive waste management at accelerator facilities.

  5. Study of muon-induced neutron production using accelerator muon beam at CERN

    SciTech Connect

    Nakajima, Y.; Lin, C. J.; Ochoa-Ricoux, J. P.; Draeger, E.; White, C. G.; Luk, K. B.; Steiner, H.

    2015-08-17

    Cosmogenic muon-induced neutrons are one of the most problematic backgrounds for various underground experiments for rare event searches. In order to accurately understand such backgrounds, experimental data with high-statistics and well-controlled systematics is essential. We performed a test experiment to measure muon-induced neutron production yield and energy spectrum using a high-energy accelerator muon beam at CERN. We successfully observed neutrons from 160 GeV/c muon interaction on lead, and measured kinetic energy distributions for various production angles. Works towards evaluation of absolute neutron production yield is underway. This work also demonstrates that the setup is feasible for a future large-scale experiment for more comprehensive study of muon-induced neutron production.

  6. Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux

    DOEpatents

    Bowman, C.D.

    1992-11-03

    Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

  7. Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux

    DOEpatents

    Bowman, Charles D.

    1992-01-01

    Apparatus for nuclear transmutation and power production using an intense accelerator-generated thermal neutron flux. High thermal neutron fluxes generated from the action of a high power proton accelerator on a spallation target allows the efficient burn-up of higher actinide nuclear waste by a two-step process. Additionally, rapid burn-up of fission product waste for nuclides having small thermal neutron cross sections, and the practicality of small material inventories while achieving significant throughput derive from employment of such high fluxes. Several nuclear technology problems are addressed including 1. nuclear energy production without a waste stream requiring storage on a geological timescale, 2. the burn-up of defense and commercial nuclear waste, and 3. the production of defense nuclear material. The apparatus includes an accelerator, a target for neutron production surrounded by a blanket region for transmutation, a turbine for electric power production, and a chemical processing facility. In all applications, the accelerator power may be generated internally from fission and the waste produced thereby is transmuted internally so that waste management might not be required beyond the human lifespan.

  8. First experimental results from 2 MeV proton tandem accelerator for neutron production.

    PubMed

    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 2 MeV 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 (7)Li(p,n)(7)Be for the boron neutron-capture therapy of the brain tumors, and for explosive detection based on 9.1724 MeV resonance gamma, which are produced via reaction (13)C(p,gamma)(14)N, absorption in nitrogen. PMID:18315262

  9. First experimental results from 2 MeV proton tandem accelerator for neutron production

    SciTech Connect

    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.

    2008-02-15

    A 2 MeV 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 {sup 7}Li(p,n){sup 7}Be for the boron neutron-capture therapy of the brain tumors, and for explosive detection based on 9.1724 MeV resonance gamma, which are produced via reaction {sup 13}C(p,{gamma}){sup 14}N, absorption in nitrogen.

  10. Estimation of neutron production from accelerator head assembly of 15 MV medical LINAC using FLUKA simulations

    NASA Astrophysics Data System (ADS)

    Patil, B. J.; Chavan, S. T.; Pethe, S. N.; Krishnan, R.; Bhoraskar, V. N.; Dhole, S. D.

    2011-12-01

    For the production of a clinical 15 MeV photon beam, the design of accelerator head assembly has been optimized using Monte Carlo based FLUKA code. The accelerator head assembly consists of e-γ target, flattening filter, primary collimator and an adjustable rectangular secondary collimator. The accelerators used for radiation therapy generate continuous energy gamma rays called Bremsstrahlung (BR) by impinging high energy electrons on high Z materials. The electron accelerators operating above 10 MeV can result in the production of neutrons, mainly due to photo nuclear reaction (γ, n) induced by high energy photons in the accelerator head materials. These neutrons contaminate the therapeutic beam and give a non-negligible contribution to patient dose. The gamma dose and neutron dose equivalent at the patient plane (SSD = 100 cm) were obtained at different field sizes of 0 × 0, 10 × 10, 20 × 20, 30 × 30 and 40 × 40 cm 2, respectively. The maximum neutron dose equivalent is observed near the central axis of 30 × 30 cm 2 field size. This is 0.71% of the central axis photon dose rate of 0.34 Gy/min at 1 μA electron beam current.

  11. Production of 64Cu and 67Cu radiopharmaceuticals using zinc target irradiated with accelerator neutrons

    NASA Astrophysics Data System (ADS)

    Kawabata, Masako; Hashimoto, Kazuyuki; Saeki, Hideya; Sato, Nozomi; Motoishi, Shoji; Nagai, Yasuki

    2014-09-01

    Copper radioisotopes have gained a lot of attention in radiopharmaceuticals owing to their unique decay characteristics. The longest half-life β emitter, 67Cu, is thought to be suitable for targeted radio-immunotherapy. Adequate production of 67Cu to meet the demands of clinical studies has not been fully established. Another attractive copper isotope, 64Cu has possible applications as a diagnostic imaging tracer combined with a therapeutic effect. This work proposes a production method using accelerator neutrons in which two copper radioisotopes can be produced: 1) 68Zn(n,x)67Cu and 2) 64Zn(n,p)64Cu using ~14 MeV neutrons generated by natC(d, n) reaction, both from natural or enriched zinc oxides. The generated 64,67Cu were separated from the target zinc oxide using a chelating and an anion exchange columns and were labelled with two widely studied chelators where the labelling efficiency was found to be acceptably good. The major advantage of this method is that a significant amount of 64,67Cu with a very few impurity radionuclides are produced which also makes the separation procedure simple. Provided an accelerator supplying an Ed = ~ 40 MeV, a wide application of 64,67Cu based drugs in nuclear medicine is feasible in the near future. We will present the characteristics of this production method using accelerator neutrons including the chemical separation processes.

  12. Deuteron Acceleration and Fusion Neutron Production in Z-pinch plasmas

    SciTech Connect

    Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Ananeev, S. S.; Bakshaev, Yu. L.; Blinov, P. I.; Chernenko, A. S.; Kazakov, E. D.; Korolev, V. D.; Ustroev, G. I.

    2009-01-21

    Fusion neutron measurements were carried out on the S-300 generator (Kurchatov Institute, Moscow). We tried deuterated fibers, various types of wire arrays imploding onto a deuterated fiber, and deuterium gas puffs as Z-pinch loads. On the current level of 2 MA, the peak neutron yield of 10{sup 10} was achieved with a deuterium gas-puff. The neutron and deuteron energy spectra were quite similar in various types of Z-pinch configurations. The broad width of radial neutron spectra implied a high radial component of deuteron velocity. On the basis of neutron measurements, we concluded that neutron production mechanism is connected with the study of plasma voltage. It means that the acceleration of fast deuterons is not a secondary process but it reflects the global dynamics of Z-pinch plasmas. For this reason it is useful to add deuterium as a 'tracer' in Z-pinch loads more often. For instance, it seems attractive to prepare wire-arrays from deuterated metal wires such as Pd.

  13. Neutron production from a mobile linear accelerator operating in electron mode for intraoperative radiation therapy

    NASA Astrophysics Data System (ADS)

    Loi, G.; Dominietto, M.; Cannillo, B.; Ciocca, M.; Krengli, M.; Mones, E.; Negri, E.; Brambilla, M.

    2006-02-01

    Intraoperative electron beam radiotherapy is increasingly performed using mobile linac delivering therapeutic radiation doses in unshielded operating rooms. While no special neutron-shielding problem should arise for operation at 10 MeV or less, it is not clear whether this holds true for operation at higher energies. This paper reports the measured neutron production from a Mobetron mobile electron linac, operated at 12 MeV, and compares the results with those from a conventional linac, also operated at 12 MeV in electron mode. Neutron leakage measurements were performed by means of passive bubble detectors in the scattering foil, patient and floor planes. Neutron dose equivalent rates per unit of electron dose delivered by the Mobetron at its normal treatment distance (50 cm SSD) were 0.33 µSv Gy-1 at the accelerator head, 0.18 µSv Gy-1 in the patient plane at 15 cm from the beam axis and 0.31 µSv Gy-1 at the floor plane, on the beam axis and under the beam stopper. For a weekly workload of 250 Gy, the weekly neutron dose equivalents at 12 MeV for the Mobetron at a distance of 300 cm from the scattering foil were 14.3 and 1.7 µSv/week for floor below and adjoining areas on the same floor, respectively. Neutron dose equivalent rates generated from Mobetron are at least one order of magnitude lower than ones produced by a conventional linac operated at the same energy in electron mode. Mobetron can be used at 12 MeV in an unshielded operating room for a weekly workload of up to 250 Gy if the bremsstrahlung x-rays are shielded to negligible levels.

  14. Accelerators and Neutron Capture Therapy

    NASA Astrophysics Data System (ADS)

    Burlon, A. A.; Kreiner, A. J.; Valda, A.

    2002-08-01

    Within the frame of Accelerator Based Boron Neutron Capture Therapy (AB-BNCT), the 7Li (p,n) 7Be reaction, relatively near its energy threshold is one of the most promising, due to its high yield and low neutron energy. In this work a thick LiF target irradiated with a proton beam was studied as a neutron source. The 1.88-2.0 MeV proton beam was produced by the tandem accelerator TANDAR at CNEA's facilities in Buenos Aires. A water-filled phantom, containing a boron sample was irradiated with the resulting neutron flux. The 10B(n,αγ)7Li boron neutron capture reaction produces a 0.478 MeV gamma ray in 94% of the cases. The neutron yield was measured through the detection of this gamma ray using a hyperpure germanium detector with an anti-Compton shield. In addition, the thermal neutron flux was evaluated at different depths inside the phantom using bare and Cd-covered gold foils. A maximum neutron thermal flux of 1.4×108 cm-2s-1mA-1 was obtained at 4.2 cm from the phantom surface. In order to optimize the design of the neutron production target and the beam shaping assembly extensive Monte Carlo Neutron and Photon (MCNP) simulations have been performed. Neutron fields from a thick LiF and a Li metal target (with both a D2O-graphite and a Al/AlF3-graphite moderator/reflector assembly) were evaluated along the centerline of a head and a whole body phantom. Simulations were carried out for 1.89, 2.0 and 2.3 MeV proton beams. The results show that it is more advantageous to irradiate the target with 2.3 MeV near-resonance protons, instead of very near threshold, because of the higher neutron yield at this energy. On the other hand, the Al/AlF3-graphite exhibits a more efficient performance than D2O in terms of tumor to maximum healthy tissue dose ratio. Treatment times of less than 15 min and tumor control probabilities larger than 98% are obtained for a 50 mA, 2.3 MeV proton beam. The alternative neutron-producing reaction 13C(d,n) is also briefly reviewed. A

  15. Accelerator based epithermal neutron source

    NASA Astrophysics Data System (ADS)

    Taskaev, S. Yu.

    2015-11-01

    We review the current status of the development of accelerator sources of epithermal neutrons for boron neutron capture therapy (BNCT), a promising method of malignant tumor treatment. Particular attention is given to the source of epithermal neutrons on the basis of a new type of charged particle accelerator: tandem accelerator with vacuum insulation and lithium neutron-producing target. It is also shown that the accelerator with specialized targets makes it possible to generate fast and monoenergetic neutrons, resonance and monoenergetic gamma-rays, alpha-particles, and positrons.

  16. Selective Deuteron Acceleration and Neutron Production on the Vulcan PW Laser

    NASA Astrophysics Data System (ADS)

    Krygier, A. G.; Morrison, J. T.; Freeman, R. R.; Ahmed, H.; Green, J. A.; Alejo, A.; Kar, S.; Vassura, L.

    2014-10-01

    Fast neutron sources are important for a variety of applications including radiography and the detection of sensitive materials. Here we report on the results of an experiment using the Vulcan PW laser at Rutherford Appleton Laboratory to produce a nearly pure deuterium ion beam via Target Normal Sheath Acceleration. The typical contaminants are suppressed by freezing a μ m's thick layer of heavy water vapor (D2 O) onto a cryogenic target during the shot sequence. Neutrons were generated by colliding the accelerated deuterons were into secondary targets made of deuterated plastic in the pitcher-catcher arrangement. Absolute yields for deuterium ions and neutrons are reported. This work is supported by DOE Contract DE-FC02-04ER54789.

  17. Efficient neutron production from sub-nanosecond laser pulse accelerating deuterons on target front side

    SciTech Connect

    Klir, D.; Krasa, J.; Velyhan, A.; Cikhardt, J.; Rezac, K.; Dudzak, R.; Krousky, E.; Pfeifer, M.; Skala, J.; Ullschmied, J.; Sila, O.

    2015-09-15

    Neutron-producing experiments have been carried out on the Prague Asterix Laser System. At the fundamental wavelength of 1.315 μm, the laser pulse of a 600 J energy and 300 ps duration was focused on a thick deuterated-polyethylene target. Neutron yields reached (4.1 ± 0.8) × 10{sup 8} at the peak intensity of ≈3 × 10{sup 16 }W/cm{sup 2}. A more detailed analysis of neutron time-of-flight signals showed that a significant fraction of neutron yields was produced both by the {sup 2}H(d,n){sup 3}He reaction and by other neutron-producing reactions. Neutron energies together with delayed neutron and gamma emission showed that MeV deuterons escaped from a laser-produced plasma and interacted ≈50 ns later with a borosilicate blast-shield glass. In order to increase DD neutron yields and to characterize deuteron beams via nuclear reactions, a secondary deuterated polyethylene target was used in a pitcher-catcher scheme at the target front side. In this experimental arrangement, the neutron yield reached (2.0 ± 0.5) × 10{sup 9} with the peak neutron fluence of (2.5 ± 0.5) × 10{sup 8 }n/sr. From the neutron yield, it was calculated that the secondary target was bombarded by 2 × 10{sup 14} deuterons in the 0.5–2.0 MeV energy range. The neutron yield of 2 × 10{sup 9} at the laser energy of 600 J implied the production efficiency of 3 × 10{sup 6 }n/J. A very important result is that the efficient neutron production was achieved with the low contrast, sub-nanosecond laser pulse of the intensity of 10{sup 16 }W/cm{sup 2}. The latter parameters can be achieved in a rep-rate mode more easily than ultra-high intensities and contrasts.

  18. Mobile accelerator neutron radiography system

    NASA Astrophysics Data System (ADS)

    Dance, W. E.; Carollo, S. F.; Bumgardner, H. M.

    1984-10-01

    The use of neutron radiography for the inspection and maintenance of large structures such as aircraft has been delayed by the absence of a mobile system particularly suited to the requirements of field use. This report describes the production, extensive field testing, evaluation and disposition of the first mobile neutron radiography system to satisfy the majority of requirements for field use. The system is based upon the concept of a mobile on-off neutron radiography system based on a sealed-tube ion accelerator as neutron source demonstrated earlier by the Vought Corporation. Primary features of the system are its self-propelled mobility, versatile positioning capability scaled to Army helicopter dimensions, an on-off beam capability, exposure capability measured in minutes, and suitability for AMMRC laboratory and field use. Included in the report are a description of all components of the system, an evaluation of the operation of the system, an evaluation of its radiographic capabilities, a description of installation elements for the AMMRC site, and recommendations for next-generation systems.

  19. High power neutron production targets

    SciTech Connect

    Wender, S.

    1996-06-01

    The author describes issues of concern in the design of targets and associated systems for high power neutron production facilities. The facilities include uses for neutron scattering, accelerator driven transmutation, accelerator production of tritium, short pulse spallation sources, and long pulse spallation sources. Each of these applications requires a source with different design needs and consequently different implementation in practise.

  20. Dominant deuteron acceleration with a high-intensity laser for isotope production and neutron generation

    SciTech Connect

    Maksimchuk, A.; Raymond, A.; Yu, F.; Dollar, F.; Willingale, L.; Zulick, C.; Krushelnick, K.; Petrov, G. M.; Davis, J.

    2013-05-13

    Experiments on the interaction of an ultra-short pulse laser with heavy-water, ice-covered copper targets, at an intensity of 2 Multiplication-Sign 10{sup 19} W/cm{sup 2}, were performed demonstrating the generation of a 'pure' deuteron beam with a divergence of 20 Degree-Sign , maximum energy of 8 MeV, and a total of 3 Multiplication-Sign 10{sup 11} deuterons with energy above 1 MeV-equivalent to a conversion efficiency of 1.5%{+-} 0.2%. Subsequent experiments on irradiation of a {sup 10}B sample with deuterons and neutron generation from d-d reactions in a pitcher-catcher geometry, resulted in the production of {approx}10{sup 6} atoms of the positron emitter {sup 11}C and a neutron flux of (4{+-}1) Multiplication-Sign 10{sup 5} neutrons/sterad, respectively.

  1. Acceleration radioisotope production simulations

    SciTech Connect

    Waters, L.S.; Wilson, W.B.

    1996-12-31

    We have identified 96 radionuclides now being used or under consideration for use in medical applications. Previously, we calculated the production of {sup 99}Mo from enriched and depleted uranium targets at the 800-MeV energy used in the LAMPF accelerator at Los Alamos. We now consider the production of isotopes using lower energy beams, which may become available as a result of new high-intensity spallation target accelerators now being planned. The production of four radionuclides ({sup 7}Be, {sup 67}Cu, {sup 99}Mo, and {sup 195m}Pt) in a simplified proton accelerator target design is being examined. The LAHET, MCNP, and CINDER90 codes were used to model the target, transport a beam of protons and secondary produced particles through the system, and compute the nuclide production from spallation and low-energy neutron interactions. Beam energies of 200 and 400 MeV were used, and several targets were considered for each nuclide.

  2. The Spallation Neutron Source accelerator system design

    NASA Astrophysics Data System (ADS)

    Henderson, S.; Abraham, W.; Aleksandrov, A.; Allen, C.; Alonso, J.; Anderson, D.; Arenius, D.; Arthur, T.; Assadi, S.; Ayers, J.; Bach, P.; Badea, V.; Battle, R.; Beebe-Wang, J.; Bergmann, B.; Bernardin, J.; Bhatia, T.; Billen, J.; Birke, T.; Bjorklund, E.; Blaskiewicz, M.; Blind, B.; Blokland, W.; Bookwalter, V.; Borovina, D.; Bowling, S.; Bradley, J.; Brantley, C.; Brennan, J.; Brodowski, J.; Brown, S.; Brown, R.; Bruce, D.; Bultman, N.; Cameron, P.; Campisi, I.; Casagrande, F.; Catalan-Lasheras, N.; Champion, M.; Champion, M.; Chen, Z.; Cheng, D.; Cho, Y.; Christensen, K.; Chu, C.; Cleaves, J.; Connolly, R.; Cote, T.; Cousineau, S.; Crandall, K.; Creel, J.; Crofford, M.; Cull, P.; Cutler, R.; Dabney, R.; Dalesio, L.; Daly, E.; Damm, R.; Danilov, V.; Davino, D.; Davis, K.; Dawson, C.; Day, L.; Deibele, C.; Delayen, J.; DeLong, J.; Demello, A.; DeVan, W.; Digennaro, R.; Dixon, K.; Dodson, G.; Doleans, M.; Doolittle, L.; Doss, J.; Drury, M.; Elliot, T.; Ellis, S.; Error, J.; Fazekas, J.; Fedotov, A.; Feng, P.; Fischer, J.; Fox, W.; Fuja, R.; Funk, W.; Galambos, J.; Ganni, V.; Garnett, R.; Geng, X.; Gentzlinger, R.; Giannella, M.; Gibson, P.; Gillis, R.; Gioia, J.; Gordon, J.; Gough, R.; Greer, J.; Gregory, W.; Gribble, R.; Grice, W.; Gurd, D.; Gurd, P.; Guthrie, A.; Hahn, H.; Hardek, T.; Hardekopf, R.; Harrison, J.; Hatfield, D.; He, P.; Hechler, M.; Heistermann, F.; Helus, S.; Hiatt, T.; Hicks, S.; Hill, J.; Hill, J.; Hoff, L.; Hoff, M.; Hogan, J.; Holding, M.; Holik, P.; Holmes, J.; Holtkamp, N.; Hovater, C.; Howell, M.; Hseuh, H.; Huhn, A.; Hunter, T.; Ilg, T.; Jackson, J.; Jain, A.; Jason, A.; Jeon, D.; Johnson, G.; Jones, A.; Joseph, S.; Justice, A.; Kang, Y.; Kasemir, K.; Keller, R.; Kersevan, R.; Kerstiens, D.; Kesselman, M.; Kim, S.; Kneisel, P.; Kravchuk, L.; Kuneli, T.; Kurennoy, S.; Kustom, R.; Kwon, S.; Ladd, P.; Lambiase, R.; Lee, Y. Y.; Leitner, M.; Leung, K.-N.; Lewis, S.; Liaw, C.; Lionberger, C.; Lo, C. C.; Long, C.; Ludewig, H.; Ludvig, J.; Luft, P.; Lynch, M.; Ma, H.; MacGill, R.; Macha, K.; Madre, B.; Mahler, G.; Mahoney, K.; Maines, J.; Mammosser, J.; Mann, T.; Marneris, I.; Marroquin, P.; Martineau, R.; Matsumoto, K.; McCarthy, M.; McChesney, C.; McGahern, W.; McGehee, P.; Meng, W.; Merz, B.; Meyer, R.; Meyer, R.; Miller, B.; Mitchell, R.; Mize, J.; Monroy, M.; Munro, J.; Murdoch, G.; Musson, J.; Nath, S.; Nelson, R.; Nelson, R.; O`Hara, J.; Olsen, D.; Oren, W.; Oshatz, D.; Owens, T.; Pai, C.; Papaphilippou, I.; Patterson, N.; Patterson, J.; Pearson, C.; Pelaia, T.; Pieck, M.; Piller, C.; Plawski, T.; Plum, M.; Pogge, J.; Power, J.; Powers, T.; Preble, J.; Prokop, M.; Pruyn, J.; Purcell, D.; Rank, J.; Raparia, D.; Ratti, A.; Reass, W.; Reece, K.; Rees, D.; Regan, A.; Regis, M.; Reijonen, J.; Rej, D.; Richards, D.; Richied, D.; Rode, C.; Rodriguez, W.; Rodriguez, M.; Rohlev, A.; Rose, C.; Roseberry, T.; Rowton, L.; Roybal, W.; Rust, K.; Salazer, G.; Sandberg, J.; Saunders, J.; Schenkel, T.; Schneider, W.; Schrage, D.; Schubert, J.; Severino, F.; Shafer, R.; Shea, T.; Shishlo, A.; Shoaee, H.; Sibley, C.; Sims, J.; Smee, S.; Smith, J.; Smith, K.; Spitz, R.; Staples, J.; Stein, P.; Stettler, M.; Stirbet, M.; Stockli, M.; Stone, W.; Stout, D.; Stovall, J.; Strelo, W.; Strong, H.; Sundelin, R.; Syversrud, D.; Szajbler, M.; Takeda, H.; Tallerico, P.; Tang, J.; Tanke, E.; Tepikian, S.; Thomae, R.; Thompson, D.; Thomson, D.; Thuot, M.; Treml, C.; Tsoupas, N.; Tuozzolo, J.; Tuzel, W.; Vassioutchenko, A.; Virostek, S.; Wallig, J.; Wanderer, P.; Wang, Y.; Wang, J. G.; Wangler, T.; Warren, D.; Wei, J.; Weiss, D.; Welton, R.; Weng, J.; Weng, W.-T.; Wezensky, M.; White, M.; Whitlatch, T.; Williams, D.; Williams, E.; Wilson, K.; Wiseman, M.; Wood, R.; Wright, P.; Wu, A.; Ybarrolaza, N.; Young, K.; Young, L.; Yourd, R.; Zachoszcz, A.; Zaltsman, A.; Zhang, S.; Zhang, W.; Zhang, Y.; Zhukov, A.

    2014-11-01

    The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. Department of Energy national laboratories. The SNS accelerator system consists of a 1 GeV linear accelerator and an accumulator ring providing 1.4 MW of proton beam power in microsecond-long beam pulses to a liquid mercury target for neutron production. The accelerator complex consists of a front-end negative hydrogen-ion injector system, an 87 MeV drift tube linear accelerator, a 186 MeV side-coupled linear accelerator, a 1 GeV superconducting linear accelerator, a 248-m circumference accumulator ring and associated beam transport lines. The accelerator complex is supported by ~100 high-power RF power systems, a 2 K cryogenic plant, ~400 DC and pulsed power supply systems, ~400 beam diagnostic devices and a distributed control system handling ~100,000 I/O signals. The beam dynamics design of the SNS accelerator is presented, as is the engineering design of the major accelerator subsystems.

  3. ACCELERATOR BASED CONTINUOUS NEUTRON SOURCE.

    SciTech Connect

    SHAPIRO,S.M.; RUGGIERO,A.G.; LUDEWIG,H.

    2003-03-25

    Until the last decade, most neutron experiments have been performed at steady-state, reactor-based sources. Recently, however, pulsed spallation sources have been shown to be very useful in a wide range of neutron studies. A major review of neutron sources in the US was conducted by a committee chaired by Nobel laureate Prof. W. Kohn: ''Neutron Sources for America's Future-BESAC Panel on Neutron Sources 1/93''. This distinguished panel concluded that steady state and pulsed sources are complementary and that the nation has need for both to maintain a balanced neutron research program. The report recommended that both a new reactor and a spallation source be built. This complementarity is recognized worldwide. The conclusion of this report is that a new continuous neutron source is needed for the second decade of the 20 year plan to replace aging US research reactors and close the US neutron gap. it is based on spallation production of neutrons using a high power continuous superconducting linac to generate protons impinging on a heavy metal target. There do not appear to be any major technical challenges to the building of such a facility since a continuous spallation source has been operating in Switzerland for several years.

  4. Linear accelerator for tritium production

    SciTech Connect

    Garnett, R.W.; Billen, J.H.; Chan, K.C.; Genzlinger, R.; Gray, E.R.; Nath, S.; Rusnak, B.; Schrage, D.L.; Stovall, J.E.; Takeda, H.; Wood, R.; Wangler, T.P.; Young, L.M.

    1996-06-01

    For many years now, Los Alamos National Laboratory has been working to develop a conceptual design of a facility for accelerator production of tritium (APT). The APT accelerator will produce high energy protons which will bombard a heavy metal target, resulting in the production of large numbers of spallation neutrons. These neutrons will be captured by a low-{ital Z} target to produce tritium. This paper describes the latest design of a room-temperature, 1.0 GeV, 100 mA, cw proton accelerator for tritium production. The potential advantages of using superconducting cavities in the high-energy section of the linac are also discussed and a comparison is made with the baseline room-temperature accelerator. {copyright} {ital 1996 American Institute of Physics.}

  5. Neutron production in deuterium gas-puff implosions on the refurbished Z accelerator.

    SciTech Connect

    Flicker, Dawn G.; Coverdale, Christine Anne; Velikovich, Aleksandr Lazarevich; Clark, R. W.; Chong, Y. K.; Davis, J.; Giuliani, J. L.

    2010-06-01

    It has been experimentally demonstrated that deuterium gas-puff implosions at >15 MA are powerful sources of fusion neutrons. Analysis of these experiments indicates that a substantial fraction of the obtained DD fusion neutron yields {approx} 3 x 10{sup 13}, about 50%, might have been of thermonuclear origin. The goal of our study is to estimate the scaling of the thermonuclear neutron yield from deuterium gas-puff implosions with higher load currents available after the refurbishment of Z, both in the short-pulse ({approx}100 ns) and in the long-pulse ({approx}300 ns) implosion regimes. We report extensive ID and 2D radiation-hydrodynamic simulations of such implosions. The mechanisms of ion heating to the fusion temperatures of 7-10 keV are essentially the same as used in structured gas-puff loads to generate high Ar K-shell yields: shock thermalization of the implosion kinetic energy and subsequent adiabatic heating of the on-axis plasma. We investigate the role of high-atomic-number gas that can be added to the outer shell to improve both energy coupling of the imploded mass to the generator and energy transfer to the inner part of the load, due to radiative losses that make the outer shell thin. We analyze the effect of imposed axial magnetic field {approx}30-100 kG, which can contribute both to stabilization of the implosion and to Joule heating of the imploded plasma. Our estimates indicate that thermonuclear DD neutron yields approaching 10 are within the reach on refurbished Z.

  6. Accelerator-based neutron radioscopic systems

    NASA Astrophysics Data System (ADS)

    Berger, Harold; Dance, William E.

    1999-06-01

    There is interest in non-reactor source, thermal neutron inspection systems for applications in aircraft maintenance, explosive devices, investment-cast turbine blades, etc. Accelerator sources, (d-T), RFQ accelerators and cyclotrons as examples, are available for either transportable or fixed neutron inspection systems. Sources are reviewed for neutron output, portability, ease of use and cost, and for use with an electronic neutron imaging camera (image intensifier or scintillator-camera system) to provide a prompt response, neutron inspection system. Particular emphasis is given to the current aircraft inspection problem to detect and characterize corrosion. Systems are analyzed to determine usefulness in providing an on-line inspection technique to detect corrosion in aluminum honeycomb aircraft components, either on-aircraft or in a shop environment. The neutron imaging sensitivity to hydrogenous aluminum corrosion product offers early detection advantages for aircraft corrosion, to levels of aluminum metal loss as small as 25 μm. The practical capability for a continuous scan thermal neutron radioscopic system to inspect up to 500 square feet of component surface per day is used as an evaluation criterion, with the system showing contrast sensitivity of at least 5% and image detail in the order of 4 mm for parts 10 cm thick. Under these practical conditions and 3-shift operation, the source must provide an incident thermal neutron flux of 5.6×104n cm-2 s-1 at an L/D of 30. A stop and go inspection approach, offering improved resolution, would require a source with similar characteristics.

  7. Optimizing pulse shaping and zooming for acceleration to high velocities and fusion neutron production on the Nike laser

    NASA Astrophysics Data System (ADS)

    Karasik, Max; Weaver, J. L.; Aglitskiy, Y.; Zalesak, S. T.; Velikovich, A. L.; Oh, J.; Obenschain, S. P.; Arikawa, Y.; Watari, T.

    2010-11-01

    We will present results from follow-on experiments to the record-high velocities of 1000 km/s achieved on Nike [Karasik et al., Phys. Plasmas 17, 056317 (2010) ], in which highly accelerated planar foils of deuterated polystyrene were made to collide with a witness foil to produce extreme shock pressures and result in heating of matter to thermonuclear temperatures. Still higher velocities and higher target densities are required for impact fast ignition. The aim of these experiments is shaping the driving pulse to minimize shock heating of the accelerated target and using the focal zoom capability of Nike to achieve higher densities and velocities. Spectroscopic measurements of electron temperature achieved upon impact will complement the neutron time-of-flight ion temperature measurement. Work is supported by US DOE and Office of Naval Research.

  8. Use of zooming and pulseshaping for acceleration to high velocities and fusion neutron production on the Nike laser

    NASA Astrophysics Data System (ADS)

    Karasik, Max; Weaver, J. L.; Aglitskiy, Y.; Kehne, D. M.; Zalesak, S. T.; Velikovich, A. L.; Oh, J.; Obenschain, S. P.; Arikawa, Y.

    2011-10-01

    We will present results from follow-on experiments to the record-high velocities of 1000 km/s achieved on Nike [Karasik et al, Phys. Plasmas 17, 056317(2010)], in which highly accelerated planar foils of deuterated polystyrene were made to collide with a witness foil to produce ~ 1 Gbar shock pressures and result in heating of matter to thermonuclear temperatures. Still higher velocities and higher target densities are required for impact fast ignition. The aim of these experiments is using the focal zoom capability of Nike and shaping the driving pulse to minimize shock heating of the accelerated target to achieve higher densities and velocities. In-flight target density is inferred from target heating upon collision via DD neutron time-of-flight ion temperature measurement. Work is supported by US DOE (NNSA) and Office of Naval Research. SAIC

  9. Development of a sealed-accelerator-tube neutron generator

    PubMed

    Verbeke; Leung; Vujic

    2000-10-01

    Sealed-accelerator-tube neutron generators are being developed in Lawrence Berkeley National Laboratory (LBNL) for applications ranging from neutron radiography to boron neutron capture therapy and neutron activation analysis. The new generation of high-output neutron generators is based on the D-T fusion reaction, producing 14.1-MeV neutrons. The main components of the neutron tube--the ion source, the accelerator and the target--are all housed in a sealed metal container without external pumping. Thick-target neutron yield computations are performed in this paper to estimate the neutron yield of titanium and scandium targets. With an average deuteron beam current of 1 A and an energy of 120 keV, a time-averaged neutron production of approximately 10(14) n/s can be estimated for a tritiated target, for both pulsed and cw operations. In mixed deuteron/triton beam operation, a beam current of 2 A at 150 keV is required for the same neutron output. Recent experimental results on ion sources and accelerator columns are presented and discussed. PMID:11003523

  10. Confirmatory experiments for the United States Department of Energy Accelerator Production of Tritium Program: Neutron, triton and radionuclide production by thick targets of lead and tungsten bombarded by 800 MeV protons

    SciTech Connect

    Lisowski, P.W.; Cappiello, M.; Ullmann, J.L.; Gavron, A.; King, J.D.; Laird, R.; Mayo, D.; Waters, L.; Zoeller, C.; Staples, P.

    1994-10-01

    Neutron and Triton Production by 800 MeV Protons: The experiments presented in this report were performed in support of the Accelerator Production of Tritium (APT) project at the Los Alamos Weapons Neutron Research (WNR) facility in order to provide data to benchmark and validate physics simulations used in the APT target/blanket design. An experimental apparatus was built that incorporated many of the features of the neutron source region of the {sup 3}He target/blanket. Those features included a tungsten neutron source, flux traps, neutron moderator, lead backstop, lead multiplying annulus, neutron absorbing blanket and a combination neutron de-coupler and tritium producing gas ({sup 3}He). The experiments were performed in two separate proton irradiations each with approximately 100 nA-hr of 800 MeV protons. The first irradiation was made with a small neutron moderating blanket, allowing the authors to measure tritium production in the {sup 3}He gas by sampling, and counting the amount of tritium. The second irradiation was performed with a large neutron moderating blanket (light water with a 1% manganese sulfate solution) that allowed them to measure both the tritium production in the central region and the total neutron production. The authors did this by sampling and counting the tritium produced and by measuring the activation of the manganese solution. Results of the three tritium production measurements show large disagreements with each other and therefore with the values predicted using the LAHET-MCNP code system. The source of the discrepancies may lie with the sampling system or adsorption on the tungsten surfaces. The authors discuss tests that may resolve that issue. The data for the total neutron production measurement is much more consistent. Those results show excellent agreement between calculation and experiment.

  11. First neutron generation in the BINP accelerator based neutron source.

    PubMed

    Bayanov, B; Burdakov, A; Chudaev, V; Ivanov, A; Konstantinov, S; Kuznetsov, A; Makarov, A; Malyshkin, G; Mekler, K; Sorokin, I; Sulyaev, Yu; Taskaev, S

    2009-07-01

    Pilot innovative facility for neutron capture therapy was built at Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. The results of the first experiments on neutron generation are reported and discussed. PMID:19375928

  12. Maximizing the Efficacy of Accelerator-Produced Neutrons for BNCT

    SciTech Connect

    Jay F. Kunze; J. Frank Harmon; Rajat Kudchadker; Chad L. Lee

    2000-06-04

    Production of neutrons for boron neutron capture therapy (BNCT) treatment of malignant brain tumors will best be served if the neutrons can be produced by accelerators rather than nuclear reactors. The neutron production reaction that has been most thoroughly examined using accelerators is {sup 7}Li(n, p){sup 7}Be, generally on a thick lithium target. The threshold for this reactor is 1.88 MeV, and the yield curve for neutron production rises quite rapidly up to 2.3 MeV, where the positive slope is reduced significantly. In considering the design of a neutron production device, it has been traditional to use proton energies in the 2.4- to 2.5-MeV range. Over the last several years, our group has been working with lower-energy protons, just above the threshold for neutron production. The advantage is that the neutrons produced would have much lower energy and hence need much less moderator. The principal disadvantage of operating at these near-threshold energies is that the yield from the target is substantially reduced from that at or near 2.5-MeV proton energy. Table I shows the results of calculations to find an optimum energy for 3-mA proton beam on target. In general, we have concluded that 1.96 to 1.98 MeV is probably optimum for a tumor 5 cm below the skull.

  13. Production of Epithermal Neutron Beams for BNCT

    SciTech Connect

    Colangelo, P.; Colonna, N.; Santorelli, P.; Variale, V.; Paticchio, V.; Maggipinto, G.

    1999-12-31

    Boron Neutron Capture Therapy, a promising modality for the treatment of malignant tumors, relies on the use of neutron beams of suitable energy and intensity. For deep-seated tumors, simulations indicate that the optimal neutron energy is in the epithermal region, and in particular between 1 and 10 keV. Therapeutic neutron beams of high spectral purity could be produced with low-energy accelerators, through a suitable neutron producing reaction. In this talk we present an overview of some recently investigated reactions for the production of intense epithermal neutron beams for BNCT, and their potential use towards the setup of an hospital-based BNCT facility.

  14. An Accelerator Neutron Source for BNCT

    SciTech Connect

    Blue, Thomas, E

    2006-03-14

    The overall goal of this project was to develop an accelerator-based neutron source (ABNS) for Boron Neutron Capture Therapy (BNCT). Specifically, our goals were to design, and confirm by measurement, a target assembly and a moderator assembly that would fulfill the design requirements of the ABNS. These design requirements were 1) that the neutron field quality be as good as the neutron field quality for the reactor-based neutron sources for BNCT, 2) that the patient treatment time be reasonable, 3) that the proton current required to treat patients in reasonable times be technologially achievable at reasonable cost with good reliability, and accelerator space requirements which can be met in a hospital, and finally 4) that the treatment be safe for the patients.

  15. BINP accelerator based epithermal neutron source.

    PubMed

    Aleynik, V; Burdakov, A; Davydenko, V; Ivanov, A; Kanygin, V; Kuznetsov, A; Makarov, A; Sorokin, I; Taskaev, S

    2011-12-01

    Innovative facility for neutron capture therapy has been built at BINP. This facility is based on compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915-2.5 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. In the article, diagnostic techniques for proton beam and neutrons developed are described, results of experiments on proton beam transport and neutron generation are shown, discussed, and plans are presented. PMID:21439836

  16. Observation of Neutron Skyshine from an Accelerator Based Neutron Source

    SciTech Connect

    Franklyn, C. B.

    2011-12-13

    A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >10{sup 11} n{center_dot}s{sup -1}. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

  17. Observation of Neutron Skyshine from an Accelerator Based Neutron Source

    NASA Astrophysics Data System (ADS)

    Franklyn, C. B.

    2011-12-01

    A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >1011 nṡs-1. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine.

  18. Accelerator-driven neutron source for cargo screening

    NASA Astrophysics Data System (ADS)

    Ludewigt, B. A.; Bleuel, D. L.; Hoff, M. D.; Kwan, J. W.; Li, D.; Ratti, A.; Staples, J. W.; Virostek, S. P.; Wells, R. P.

    2007-08-01

    Advanced neutron interrogation systems for screening sea-land cargo containers for shielded special nuclear materials (SNM) require a high-yield neutron source to achieve the desired detection probability, false alarm rate, and throughput. The design of an accelerator-driven neutron source is described that utilizes the D(d,n)3He reaction to produce a forward directed beam of up to 8.5 MeV neutrons. The key components of the neutron source are a high-current radio frequency quadrupole (RFQ) accelerator and a neutron production gas target. The 5.1 m long, 200 MHz RFQ accelerates a 40 mA deuteron beam from a microwave-driven ion source coupled to an electrostatic low energy beam transport (LEBT) system to 6 MeV. At a 5% duty factor, the time-average D+ beam current on target is 1.5 mA. A thin entrance window has been designed for the deuterium gas target that can withstand the high beam power and the gas pressure. The source will be capable of delivering a flux >1 × 107 n/(cm2 s) at a distance of 2.5 m from the target and will allow full testing and demonstration of a cargo screening system based on neutron stimulated SNM signatures.

  19. Accelerator based epithermal neutron source for neutron capture therapy

    SciTech Connect

    Brugger, R.; Kunze, J.

    1991-05-01

    Several investigators have suggested that a charged particle accelerator with light element reactions might be able to produce enough epithermal neutrons to be useful in Neutron Capture Therapy. The reaction choice so far has been the Li(p,n) reaction with protons up to 2.5 MeV. A moderator around the target would reduce the faster neutrons down to the epithermal energy region. The goals of the present research are: identify better reactions; improve the moderators; and find better combinations of 1 and 2. The target is to achieve, at the patient location, an epithermal neutron current of greater than 10{sup 9}n/cm{sup 2}sec, with a dose to tissue from the neutrons alone of less than 10{sup {minus}10} rads/n and a dose from the gamma rays in the beam of less than 10{sup {minus}10} rads/n.

  20. Accelerator-based neutron source for the neutron-capture and fast neutron therapy at hospital

    NASA Astrophysics Data System (ADS)

    Bayanov, B. F.; Belov, V. P.; Bender, E. D.; Bokhovko, M. V.; Dimov, G. I.; Kononov, V. N.; Kononov, O. E.; Kuksanov, N. K.; Palchikov, V. E.; Pivovarov, V. A.; Salimov, R. A.; Silvestrov, G. I.; Skrinsky, A. N.; Soloviov, N. A.; Taskaev, S. Yu.

    The proton accelerator complex for neutron production in lithium target discussed, which can operate in two modes. The first provides a neutron beam kinematically collimated with good forward direction in 25° and average energy of 30 keV, directly applicable for neutron-capture therapy with high efficiency of proton beam use. The proton energy in this mode is 1.883-1.890 MeV that is near the threshold of the 7Li( p, n) 7Be reaction. In the second mode, at proton energy of 2.5 MeV, the complex-produced neutron beam with maximum energy board of 790 keV which can be used directly for fast neutron therapy and for neutron-capture therapy after moderation. The project of such a neutron source is based on the 2.5 MeV original electrostatic accelerator tandem with vacuum insulation developed at BINP which is supplied with a high-voltage rectifier. The rectifier is produced in BINP as a part of ELV-type industrial accelerator. Design features of the tandem determining its high reliability in operation with a high-current (up to 40 mA) H - ion beam are discussed. They are: the absence of ceramic accelerator columns around the beam passage region, good conditions for pumping out of charge-exchange gaseous target region, strong focusing optics and high acceleration rate minimizing the space charge effects. The possibility of stabilization of protons energy with an accuracy level of 0.1% necessary for operation in the near threshold region is considered. The design description of H - continuous ion source with a current of 40 mA is also performed. To operate with a 100 kW proton beam it is proposed to use liquid-lithium targets. A thin lithium layer on the surface of a tungsten disk cooled intensively by a liquid metal heat carrier is proposed for use in case of the vertical beam, and a flat liquid lithium jet flowing through the narrow nozzle - for the horizontal beam.

  1. Accelerator Based Neutron Beams for Neutron Capture Therapy

    SciTech Connect

    Yanch, Jacquelyn C.

    2003-04-11

    The DOE-funded accelerator BNCT program at the Massachusetts Institute of Technology has resulted in the only operating accelerator-based epithermal neutron beam facility capable of generating significant dose rates in the world. With five separate beamlines and two different epithermal neutron beam assemblies installed, we are currently capable of treating patients with rheumatoid arthritis in less than 15 minutes (knee joints) or 4 minutes (finger joints) or irradiating patients with shallow brain tumors to a healthy tissue dose of 12.6 Gy in 3.6 hours. The accelerator, designed by Newton scientific Incorporated, is located in dedicated laboratory space that MIT renovated specifically for this project. The Laboratory for Accelerator Beam Applications consists of an accelerator room, a control room, a shielded radiation vault, and additional laboratory space nearby. In addition to the design, construction and characterization of the tandem electrostatic accelerator, this program also resulted in other significant accomplishments. Assemblies for generating epithermal neutron beams were designed, constructed and experimentally evaluated using mixed-field dosimetry techniques. Strategies for target construction and target cooling were implemented and tested. We demonstrated that the method of submerged jet impingement using water as the coolant is capable of handling power densities of up to 6 x 10(sup 7) W/m(sup 2) with heat transfer coefficients of 10(sup 6)W/m(sup 2)-K. Experiments with the liquid metal gallium demonstrated its superiority compared with water with little effect on the neutronic properties of the epithermal beam. Monoenergetic proton beams generated using the accelerator were used to evaluate proton RBE as a function of LET and demonstrated a maximum RBE at approximately 30-40 keV/um, a finding consistent with results published by other researchers. We also developed an experimental approach to biological intercomparison of epithermal beams and

  2. Target studies for accelerator-based boron neutron capture therapy

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Todosow, M.; Reich, M.

    1996-03-01

    Two new concepts, NIFTI and DISCOS, are described. These concepts enable the efficient production of epithermal neutrons for BNCT (Boron Neutron Capture Therapy) medical treatment, utilizing a low current, low energy proton beam impacting on a lithium target. The NIFTI concept uses an iron layer that strongly impedes the transmission of neutrons with energies above 24 KeV. Lower energy neutrons readily pass through this iron ``filter``, which has a deep ``window`` in its scattering cross section at 24 KeV. The DISCOS concept uses a rapidly rotating, high g disc to create a series of thin ({approximately} 1 micron thickness) liquid lithium targets in the form of continuous films through which the proton beam passes. The average energy lost by a proton as it passes through a single target is small, approximately 10 KeV. Between the targets, the proton beam is reaccelerated by an applied DC electric field. The DISCOS approach enables the accelerator -- target facility to operate with a beam energy only slightly above the threshold value for neutron production -- resulting in an output beam of low-energy epithermal neutrons -- while achieving a high yield of neutrons per milliamp of proton beam current.

  3. Proton acceleration in neutron star magnetospheres

    NASA Technical Reports Server (NTRS)

    Smith, I. A.; Katz, J. I.; Diamond, P. H.

    1992-01-01

    To explain the emission of TeV and PeV gamma rays from accreting X-ray binary sources, protons must be accelerated to several times the gamma-ray energy. It is shown here that at certain times, the plasma in the accretion column of the neutron star may form a deep enough pool that the top portion becomes unstable to convective motions in spite of the strong magnetic field. The resulting turbulence produces fluctuations in the strength of the magnetic field that travel up the accretion column, taking energy out to the region of the energetic protons. The protons resonantly absorb this energy and are accelerated to high energies. Including the synchrotron radiation losses of the protons, it is shown that they can be accelerated to energies that are high enough to explain the gamma-ray observations.

  4. Neutron emission from fission fragments during acceleration p

    SciTech Connect

    Hinde, D.J.; Charity, R.J.; Foote, G.S.; Leigh, J.R.; Newton, J.O.; Ogaza, S.; Chatterjee, A.

    1984-03-19

    Fission-neutron angular correlations following fusion of /sup 19/F and /sup 232/Th have been measured. Conventional analysis, based on the approximation that post-fission neutrons originate only from fully accelerated fission fragments, gives unexpectedly large numbers of ''prefission'' neutrons. Comparison with the considerably less fissile system /sup 200/Pb gives the first convincing evidence that this approach is inadequate. Consideration of neutron emission from the accelerating fragments gives results consistent with expectations.

  5. Generation of nanosecond neutron pulses in vacuum accelerating tubes

    NASA Astrophysics Data System (ADS)

    Didenko, A. N.; Shikanov, A. E.; Rashchikov, V. I.; Ryzhkov, V. I.; Shatokhin, V. L.

    2014-06-01

    The generation of neutron pulses with a duration of 1-100 ns using small vacuum accelerating tubes is considered. Two physical models of acceleration of short deuteron bunches in pulse neutron generators are described. The dependences of an instantaneous neutron flux in accelerating tubes on the parameters of pulse neutron generators are obtained using computer simulation. The results of experimental investigation of short-pulse neutron generators based on the accelerating tube with a vacuum-arc deuteron source, connected in the circuit with a discharge peaker, and an accelerating tube with a laser deuteron source, connected according to the Arkad'ev-Marx circuit, are given. In the experiments, the neutron yield per pulse reached 107 for a pulse duration of 10-100 ns. The resultant experimental data are in satisfactory agreement with the results of computer simulation.

  6. Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator

    NASA Astrophysics Data System (ADS)

    Hahn, K. D.; Chandler, G. A.; Ruiz, C. L.; Cooper, G. W.; Gomez, M. R.; Slutz, S.; Sefkow, A. B.; Sinars, D. B.; Hansen, S. B.; Knapp, P. F.; Schmit, P. F.; Harding, E.; Jennings, C. A.; Awe, T. J.; Geissel, M.; Rovang, D. C.; Torres, J. A.; Bur, J. A.; Cuneo, M. E.; Glebov, V. Yu; Harvey-Thompson, A. J.; Herrman, M. C.; Hess, M. H.; Johns, O.; Jones, B.; Lamppa, D. C.; Lash, J. S.; Martin, M. R.; McBride, R. D.; Peterson, K. J.; Porter, J. L.; Reneker, J.; Robertson, G. K.; Rochau, G. A.; Savage, M. E.; Smith, I. C.; Styron, J. D.; Vesey, R. A.

    2016-05-01

    Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ∼2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρRliner∼1g/cm2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Plans to improve and expand the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.

  7. Development and testing of a deuterium gas target assembly for neutron production via the H-2(d,n)He-3 reaction at a low-energy accelerator facility

    SciTech Connect

    Feautrier, D.; Smith, D.L.

    1992-03-01

    This report describes the development and testing of a deuterium gas target intended for use at a low-energy accelerator facility to produce neutrons for basic research and various nuclear applications. The principle source reaction is H-2(d,n)He-3. It produces a nearly mono-energetic group of neutrons. However, a lower-energy continuum neutron spectrum is produced by the H-2(d;n,p)H-2 reaction and also by deuterons which strike various components in the target assembly. The present target is designed to achieve the following objectives: (1) minimize unwanted background neutron production from the target assembly, (2) provide a relatively low level of residual long-term activity within the target components, (3) have the capacity to dissipate up to 150 watts of beam power with good target longevity, and (4) possess a relatively modest target mass in order to minimize neutron scattering from the target components. The basic physical principles that have to be considered in designing an accelerator target are discussed and the major engineering features of this particular target design are outlined. The results of initial performance tests on this target are documented and some conclusions concerning the viability of the target design are presented.

  8. How to Produce a Reactor Neutron Spectrum Using a Proton Accelerator

    NASA Astrophysics Data System (ADS)

    Burns, K.; Wootan, D.; Gates, R.; Schmitt, B.; Asner, D. M.

    A method for reproducing the neutron energy spectrum present in the core of an operating nuclear reactor using an engineered target in an accelerator proton beam is proposed. The protons interact with a target to create neutrons through various (p,n) type reactions. Spectral tailoring of the emitted neutrons can be used to modify the energy of the generated neutron spectrum to represent various reactor spectra. Through the use of moderators and reflectors, the neutron spectrum can be modified to reproduce many different spectra of interest including spectra in small thermal test reactors, large pressurized water reactors, and fast reactors. The particular application of this methodology is the design of an experimental approach for using an accelerator to measure the betas produced during fission to be used to reduce uncertainties in the interpretation of reactor antineutrino measurements. This approach involves using a proton accelerator to produce a neutron field representative of a power reactor, and using this neutron field to irradiate fission foils of the primary isotopes contributing to fission in the reactor, creating unstable, neutron rich fission products that subsequently beta decay and emit electron antineutrinos. A major advantage of an accelerator neutron source over a neutron beam from a thermal reactor is that the fast neutrons can be slowed down or tailored to approximate various power reactor spectra. An accelerator based neutron source that can be tailored to match various reactor neutron spectra provides an advantage for control in studying how changes in the neutron spectra affect parameters such as the resulting fission product beta spectrum.

  9. How to produce a reactor neutron spectrum using a proton accelerator

    SciTech Connect

    Burns, Kimberly A.; Wootan, David W.; Gates, Robert O.; Schmitt, Bruce E.; Asner, David M.

    2015-01-01

    A method for reproducing the neutron energy spectrum present in the core of an operating nuclear reactor using an engineered target in an accelerator proton beam is proposed. The protons interact with a target to create neutrons through various (p,n) type reactions. Spectral tailoring of the emitted neutrons can be used to modify the energy of the generated neutron spectrum to represent various reactor spectra. Through the use of moderators and reflectors, the neutron spectrum can be modified to reproduce many different spectra of interest including spectra in small thermal test reactors, large pressurized water reactors, and fast reactors. The particular application of this methodology is the design of an experimental approach for using an accelerator to measure the betas produced during fission to be used to reduce uncertainties in the interpretation of reactor antineutrino measurements. This approach involves using a proton accelerator to produce a neutron field representative of a power reactor, and using this neutron field to irradiate fission foils of the primary isotopes contributing to fission in the reactor, creating unstable, neutron rich fission products that subsequently beta decay and emit electron antineutrinos. A major advantage of an accelerator neutron source over a neutron beam from a thermal reactor is that the fast neutrons can be slowed down or tailored to approximate various power reactor spectra. An accelerator based neutron source that can be tailored to match various reactor neutron spectra provides an advantage for control in studying how changes in the neutron spectra affect parameters such as the resulting fission product beta spectrum.

  10. First experiments on neutron detection on the accelerator-based source for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. S.; Malyshkin, G. N.; Makarov, A. N.; Sorokin, I. N.; Sulyaev, Yu. S.; Taskaev, S. Yu.

    2009-04-01

    A pilot accelerator-based source of epithermal neutrons, which is intended for wide application in clinics for boron neutron capture therapy, has been constructed at the Budker Institute of Nuclear Physics (Novosibirsk). A stationary proton beam has been obtained and near-threshold neutron generation regime has been realized. Results of the first experiments on neutron generation using the proposed source are described.

  11. Linear accelerator for production of tritium: Physics design challenges

    SciTech Connect

    Wangler, T.P.; Lawrence, G.P.; Bhatia, T.S.; Billen, J.H.; Chan, K.C.D.; Garnett, R.W.; Guy, F.W.; Liska, D.; Nath, S.; Neuschaefer, G.; Shubaly, M.

    1990-01-01

    In the summer of 1989, a collaboration between Los Alamos National Laboratory and Brookhaven National Laboratory conducted a study to establish a reference design of a facility for accelerator production of tritium (APT). The APT concept is that of a neutron-spallation source, which is based on the use of high-energy protons to bombard lead nuclei, resulting in the production of large quantities of neutrons. Neutrons from the lead are captured by lithium to produce tritium. This paper describes the design of a 1.6-GeV, 250-mA proton cw linear accelerator for APT.

  12. An accelerator-based epithermal photoneutron source for boron neutron capture therapy

    SciTech Connect

    Mitchell, H.E.

    1996-04-01

    Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 10{sup 7} neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF{sub 3} composite and a stacked Al/Teflon design) at various incident electron energies.

  13. 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.

  14. Windowless gas targets for neutron production

    NASA Astrophysics Data System (ADS)

    Iverson, Erik. B.; Lanza, Richard C.; Lidsky, L. M.

    1997-02-01

    A windowless deuterium gas target has been constructed for either monoenergetic or white neutron production with a 900 KeV deuteron accelerator. The target is capable of operation at 100 mbar target pressure, and can admit a beam of 5 mm transverse extent. This target is further being modified by the inclusion of an intermittent valve arrangement to reduce the flow rates in the higher pressure stages. This valve should allow operation at up to 1000 mbar with low duty factor beams.

  15. Optimizing Laser-accelerated Ion Beams for a Collimated Neutron Source

    SciTech Connect

    C.L. Ellison and J. Fuchs

    2010-09-23

    High-flux neutrons for imaging and materials analysis applications have typically been provided by accelerator- and reactor-based neutron sources. A novel approach is to use ultraintense (>1018W/cm2) lasers to generate picosecond, collimated neutrons from a dual target configuration. In this article, the production capabilities of present and upcoming laser facilities are estimated while independently maximizing neutron yields and minimizing beam divergence. A Monte-Carlo code calculates angular and energy distributions of neutrons generated by D-D fusion events occurring within a deuterated target for a given incident beam of D+ ions. Tailoring of the incident distribution via laser parameters and microlens focusing modifies the emerging neutrons. Projected neutron yields and distributions are compared to conventional sources, yielding comparable on-target fluxes per discharge, shorter time resolution, larger neutron energies and greater collimation.

  16. The Accelerator Production of Tritium (APT) Project*

    NASA Astrophysics Data System (ADS)

    Lisowski, Paul W.

    1997-05-01

    A reliable supply of tritium is necessary to maintain the United States' nuclear defense capability. Because tritium decays to ^3He at the rate of 5.5 percent per year, it must be replenished continously. To make the required amount of tritium using an accelerator, neutrons will be generated by high-energy proton reactions with tungsten and lead, moderated in light water, and captured in ^3He. The plant will be operational in 2007 at the Department of Energy's Savannah River Site in South Carolina. It will consist of a proton linear accelerator, tritium-production target/blankets, tritium-extraction, and conventional balance-of-plant systems. The accelerator will be a radio-frequency linac operating at 100 percent duty factor. It will have a combination of normal-conducting copper structures to accelerate a 100-mA beam to 217 MeV followed by superconducting niobium cavities to boost the beam energy to 1700 MeV. After acceleration, a high-energy transport system will expand the beam to a rectangular, 16-cm wide by 160-cm high distribution and deliver it to one of two identical target/blanket assemblies where tritium production and extraction will take place. Inside a target/blanket the proton beam will strike heavy-water cooled tungsten rods to produce neutrons. The tungsten will be surrounded by a decoupler consisting of aluminum tubes containing ^3He to reduce parasitic capture. Additional lead modules with aluminum tubes containing ^3He will lie outside the central region. The lead will produce additional neutrons from spallation and (n,xn) reactions. Light water coolant continuously circulated through the lead will moderate the neutrons to low energy, where they will be efficiently captured by ^3He gas to produce tritium. Tritium will be removed by continuous separation using permeation through a heated palladium-silver alloy membrane. Once separated, standard cryogenic distillation techniques will be used to isotopically purify the tritium. This presentation

  17. 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.

  18. Neutron Scattering Simulations at the University of Kentucky Accelerator Laboratory

    NASA Astrophysics Data System (ADS)

    Nguyen, Thienan; Jackson, Daniel; Hicks, S. F.; Rice, Ben; Vanhoy, J. R.

    2015-10-01

    The Monte-Carlo N-Particle Transport code (MCNP) has many applications ranging from radiography to reactor design. It has particle interaction capabilities, making it useful for simulating neutron collisions on surfaces of varying compositions. The neutron flux within the accelerator complex at the University of Kentucky was simulated using MCNP. With it, the complex's capabilities to contain and thermalize 7 MeV neutrons produced via 2H(d,n)3He source reaction to an acceptable level inside the neutron hall and adjoining rooms were analyzed. This will aid in confirming the safety of researchers who are working in the adjacent control room. Additionally, the neutron transport simulation was used to analyze the impact of the collimator copper shielding on various detectors located around the neutron scattering hall. The purpose of this was to attempt to explain any background neutrons that are observed at these detectors. The simulation shows that the complex performs very well with regards to neutron containment and thermalization. Also, the tracking information for the paths taken by the neutrons show that most of the neutrons' lives are spent inside the neutron hall. Finally, the neutron counts were analyzed at the positions of the neutron monitor detectors located at 90 and 45 degrees relative to the incident beam direction. This project was supported in part by the DOE NEUP Grant NU-12-KY-UK-0201-05 and the Donald A. Cowan Physics Institute at the University of Dallas.

  19. The Need for a Neutron Source at the Rare Isotope Accelerator

    SciTech Connect

    Ahle, L E; Rusnak, B; Roberts, K E; Roeben, M D; Hausmann, M; Reifarth, R; Vieira, D

    2005-05-13

    An intense neutron source facility with radiochemical processing capability is necessary at the Rare Isotope Accelerator to fully realize its potential benefit to stockpile stewardship and astrophysics. While many of the important physics missions of RIA can be addressed with radioactive ion beams, direct neutron cross-section measurements of interest to stockpile stewardship and astrophysics cannot because one cannot make a neutron target. Thus, one must collect a sufficient amount of the appropriate short-lived isotope, quickly chemically process the material into a target, and promptly radiate the sample with an intense ''beam'' of neutrons. The unprecedented production rates expected at RIA enables many of these direct neutron cross-section measurements, but only if the proper infrastructure is in place. This document not only describes the major piece of this required infrastructure, a neutron source facility with radiochemical processing capabilities, but also the motivation for measuring such direct neutron cross-sections.

  20. Leakage neutron radiation in a medical electron accelerator

    NASA Astrophysics Data System (ADS)

    Paredes, Lydia; Balcazar, Miguel; Genis, Roberto; Ortiz, Raúl

    2001-10-01

    A simple method was used for the calculation of neutron yield produced by main components of medical electron accelerator head, using a simplified geometric model with spherical-shell for the head shielding made of different materials. The leakage neutron radiation on the patient plane and outside the patient plane at one meter from the x-ray target for a Varian accelerator model Clinac 2100C was evaluated experimentally, using Panasonic UD-802 and UD-809 thermoluminescent dosimeters and CR-39 nuclear track dosimeters. The measured values of leakage neutron radiation were lower than the limits specified in the NCRP-102 and IEC 60601-2-1-Ed.2.0 reports.

  1. Using a Tandem Pelletron accelerator to produce a thermal neutron beam for detector testing purposes.

    PubMed

    Irazola, L; Praena, J; Fernández, B; Macías, M; Bedogni, R; Terrón, J A; Sánchez-Nieto, B; Arias de Saavedra, F; Porras, I; Sánchez-Doblado, F

    2016-01-01

    Active thermal neutron detectors are used in a wide range of measuring devices in medicine, industry and research. For many applications, the long-term stability of these devices is crucial, so that very well controlled neutron fields are needed to perform calibrations and repeatability tests. A way to achieve such reference neutron fields, relying on a 3 MV Tandem Pelletron accelerator available at the CNA (Seville, Spain), is reported here. This paper shows thermal neutron field production and reproducibility characteristics over few days. PMID:26595777

  2. Intense Pulsed Neutron Emission from a Compact Pyroelectric Driven Accelerator

    SciTech Connect

    Tang, V; Meyer, G; Falabella, S; Guethlein, G; Sampayan, S; Kerr, P; Rusnak, B; Morse, J

    2008-10-08

    Intense pulsed D-D neutron emission with rates >10{sup 10} n/s during the pulse, pulse widths of {approx}100's ns, and neutron yields >10 k per pulse are demonstrated in a compact pyroelectric accelerator. The accelerator consists of a small pyroelectric LiTaO{sub 3} crystal which provides the accelerating voltage and an independent compact spark plasma ion source. The crystal voltage versus temperature is characterized and compare well with theory. Results show neutron output per pulse that scales with voltage as V{approx}1.7. These neutron yields match a simple model of the system at low voltages but are lower than predicted at higher voltages due to charge losses not accounted for in the model. Interpretation of the data against modeling provides understanding of the accelerator and in general pyroelectric LiTaO{sub 3} crystals operated as charge limited negative high voltage targets. The findings overall serve as the proof-of-principle and basis for pyroelectric neutron generators that can be pulsed, giving peak neutron rates orders of magnitude greater than previous work, and notably increase the potential applications of pyroelectric based neutron generators.

  3. Accelerator-based Neutron Fluence Standard of the National Metrology Institute of Japan

    NASA Astrophysics Data System (ADS)

    Harano, Hideki; Matsumoto, Tetsuro; Nishiyama, Jun; Uritani, Akira; Kudo, Katsuhisa

    2009-03-01

    We report the present status of the national standard on accelerator-based fast neutron fluences in Japan. Monoenergetic neutron fluence standards have been established at 144 keV, 565 keV, 5.0 MeV and 8.0 MeV by using a Van de Graaff accelerator and at 2.5 MeV and 14.8 MeV by using a Cockcroft Walton accelerator. These standards are prepared to measure the detection efficiency and the energy response of neutron sensitive devices, such as personal dosimeters and survey meters. Neutron production and absolute fluence measurement for these energies are described. We are developing a new standard in the energy region of a few tens of keV, which is also introduced here as well as our future plans.

  4. High Intensity Accelerator and Neutron Source in China

    SciTech Connect

    Guan Xialing; Wei, J.; Loong Chun

    2011-06-28

    High intensity Accelerator is being studied all over world for numerous applications, which includes the waste transmutation, spallation neutron source and material irradiation facilities. The R/D activities of the technology of High intensity accelerator are also developed in China for some year, and have some good facilities around China. This paper will reports the status of some high intensity accelerators and neutron source in China, which including ADS/RFQ; CARR; CSNS; PKUNIFTY and CPHS. This paper will emphatically report the Compact Pulsed Hadron Source (CPHS) led by the Department of Engineering Physics of Tsinghua University in Beijing, China.

  5. Accretion Acceleration of Neutron Stars and Effects of Gravitational Radiation

    NASA Astrophysics Data System (ADS)

    Fu, Yan-yan; Zhang, Yue-zhu; Wei, Yi-huan; Zhang, Cheng-min; Yu, Shao-hua; Pan, Yuan-yue; Guo, Yuan-qi; Wang, De-hua

    2016-01-01

    In this paper we studied the neutron star's spin acceleration in the accretion process of the neutron star binary system, and the relation how the spin period changes with the accreted mass. We analyzed further the evolutions of both magnetic field and spin period of a neutron star, and compared the modeled results with the observational data of pulsars, to show that they are consistent with each other. Based on above studies, we investigated the effect of gravitational radiation on the spin-up process of a neutron star, and derived the change rate of the neutron star's spin period in the accretion process. We also estimated the critical angular velocity Ωcr, at which the accretion torque is balanced by that of gravitational radiation, and discussed the influence of gravitational radiation on the neutron star's spin evolution.

  6. Acceleration and deceleration of neutrons: From the phase modulation of a neutron wave to a neutron turbine with refracting prisms

    SciTech Connect

    Frank, A. I.

    2013-05-15

    The possibility of the acceleration and deceleration of neutrons undergoing diffraction at a moving grating is discussed. It is shown that, in contrast to phase {pi} gratings used at the present time, which form a discrete spectrum featuring a large number of lines, a grating that has a special profile may shift, under certain conditions, the entire spectrum of diffracted neutrons. A blazing grating of this type may be used in efficiently accelerating and decelerating neutrons. As the scale of the structure becomes larger, a description based on the idea of neutron-wave refraction at its elements becomes valid, a system of moving prims forming a 'neutron turbine,' which is also able to accelerate or decelerate neutrons, being a classical limit of this enlargement.

  7. Novel neutron sources at the Radiological Research Accelerator Facility.

    PubMed

    Xu, Yanping; Garty, Guy; Marino, Stephen A; Massey, Thomas N; Randers-Pehrson, Gerhard; Johnson, Gary W; Brenner, David J

    2012-03-16

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons.We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target.A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a Proton Microbeam, impinging on a thin lithium target near the threshold of the (7)Li(p,n)(7)Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components. PMID:22545061

  8. Novel neutron sources at the Radiological Research Accelerator Facility

    DOE PAGESBeta

    Xu, Yanping; Garty, G.; Marino, S. A.; Massey, Thomas Neal; Johnson, G. W.; Randers-Pehrson, Gerhard; Brenner, D. J.

    2012-03-16

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will bemore » based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the Li-7(p,n)Be-7 reaction. Lastly, this novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.« less

  9. Novel neutron sources at the Radiological Research Accelerator Facility

    PubMed Central

    Xu, Yanping; Garty, Guy; Marino, Stephen A.; Massey, Thomas N.; Randers-Pehrson, Gerhard; Johnson, Gary W.; Brenner, David J.

    2012-01-01

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10–20 micron in diameter. This facility is based on a Proton Microbeam, impinging on a thin lithium target near the threshold of the 7Li(p,n)7Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components. PMID:22545061

  10. Novel neutron sources at the Radiological Research Accelerator Facility

    SciTech Connect

    Xu, Yanping; Garty, G.; Marino, S. A.; Massey, Thomas Neal; Johnson, G. W.; Randers-Pehrson, Gerhard; Brenner, D. J.

    2012-03-16

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the Li-7(p,n)Be-7 reaction. Lastly, this novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.

  11. Novel neutron sources at the Radiological Research Accelerator Facility

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Garty, G.; Marino, S. A.; Massey, T. N.; Randers-Pehrson, G.; Johnson, G. W.; Brenner, D. J.

    2012-03-01

    Since the 1960s, the Radiological Research Accelerator Facility (RARAF) has been providing researchers in biology, chemistry and physics with advanced irradiation techniques, using charged particles, photons and neutrons. We are currently developing a unique facility at RARAF, to simulate neutron spectra from an improvised nuclear device (IND), based on calculations of the neutron spectrum at 1.5 km from the epicenter of the Hiroshima atom bomb. This is significantly different from a standard fission spectrum, because the spectrum changes as the neutrons are transported through air, and is dominated by neutron energies between 0.05 and 8 MeV. This facility will be based on a mixed proton/deuteron beam impinging on a thick beryllium target. A second, novel facility under development is our new neutron microbeam. The neutron microbeam will, for the first time, provide a kinematically collimated neutron beam, 10-20 micron in diameter. This facility is based on a proton microbeam, impinging on a thin lithium target near the threshold of the 7Li(p,n)7Be reaction. This novel neutron microbeam will enable studies of neutron damage to small targets, such as single cells, individual organs within small animals or microelectronic components.

  12. Neutron and gamma-ray signatures for particle acceleration in solar flares

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Murphy, R. J.

    1984-01-01

    The production of neutrons, 4 to 7 MeW nuclear gamma rays, positrons and pions resulting from the interaction of flare accelerated particles with the solar atmosphere was calculated. For the energy spectra of these particles the Bessel function predicted by stochastic acceleration and power laws which could result from acceleration at large-scale planar shocks was used, with the thick-target model. It is assumed that in the interaction region the accelerated particles are isotropic. The neutron-to-2.223 MeV photon conversion factors for various flare locations on the Sun are derived by averaging conversion factors over these spectra. Comparing calculations with data confirms that for most gamma-ray flares the bulk of the accelerated particles remain trapped at the Sun and that these particles have spectra similar to the spectra of flare particles observed in interplanetary space.

  13. Accelerator-driven boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Edgecock, Rob

    2014-05-01

    Boron Neutron Capture Therapy is a binary treatment for certain types of cancer. It works by loading the cancerous cells with a boron-10 carrying compound. This isotope has a large cross-section for thermal neutrons, the reaction producing a lithium nucleus and alpha particle that kill the cell in which they are produced. Recent studies of the boron carrier compound indicate that the uptake process works best in particularly aggressive cancers. Most studied is glioblastoma multiforme and a trial using a combination of BNCT and X-ray radiotherapy has shown an increase of nearly a factor of two in mean survival over the state of the art. However, the main technical problem with BNCT remains producing a sufficient flux of neutrons for a reasonable treatment duration in a hospital environment. This paper discusses this issue.

  14. NIFTI and DISCOS: New concepts for a compact accelerator neutron source for boron neutron capture therapy applications

    SciTech Connect

    Powell, J.; Ludewig, H.; Todosow, M.; Reich, M.

    1995-06-01

    Two new concepts, NIFTI and DISCOS, are described. These concepts enable the efficient production of epithermal neutrons for BNCT (Boron Neutron Capture Therapy) medical treatment, utilizing a low current, low energy proton beam impacting on a lithium target. The NIFTI concept uses fluoride compounds, such as lead or beryllium fluoride, to efficiently degrade high energy neutrons from the lithium target to the lower energies required for BNCT. The fluoride compounds are in turn encased in an iron layer that strongly impedes the transmission of neutrons with energies above 24 KeV. Lower energy neutrons readily pass through this iron filter, which has a deep window in its scattering cross section at 24 KeV. The DISCOS concept uses a rapidly rotating, high g disc to create a series of thin ({approximately} 1 micron thickness) liquid lithium targets in the form of continuous films or sheets of discrete droplets--through which the proton beam passes. The average energy lost by a proton as it passes through a single target is small, approximately 10 KeV. Between the targets, the proton beam is re-accelerated by an applied DC electric field. The DISCOS approach enables the accelerator--target facility to operate with a beam energy only slightly above the threshold value for neutron production--resulting in an output beam of low-energy epithermal neutrons--while achieving a high yield of neutrons per milliamp of proton beam current. Parametric trade studies of the NIFTI and DISCOS concepts are described. These include analyses of a broad range of NIFTI designs using the Monte carlo MCNP neutronics code, as well as mechanical and thermal-hydraulic analyses of various DISCOS designs.

  15. Fast Neutron Radiography at an RFQ Accelerator System

    NASA Astrophysics Data System (ADS)

    Daniels, G. C.; Franklyn, C. B.; Dangendorf, V.; Buffler, A.; Bromberger, B.

    This work introduces the Necsa Radio Frequency Quadrupole (RFQ) accelerator facility and its work concerning fast neutron radiography (FNR). Necsa operates a 4-5 MeV, up to 50 mA deuteron RFQ. The previous deuterium gas target station has been modified to enable producing a white neutron beam employing a solid B4C target. Furthermore, the high energy beam transport (HEBT) section is under adjustment to achieve a longer flight-path and a better focus. This work presents an overview of the facility, the modifications made, and introduces past and ongoing neutron radiography investigations.

  16. Accelerator shield design of KIPT neutron source facility

    SciTech Connect

    Zhong, Z.; Gohar, Y.

    2013-07-01

    Argonne National Laboratory (ANL) of the United States and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the design development of a neutron source facility at KIPT utilizing an electron-accelerator-driven subcritical assembly. Electron beam power is 100 kW, using 100 MeV electrons. The facility is designed to perform basic and applied nuclear research, produce medical isotopes, and train young nuclear specialists. The biological shield of the accelerator building is designed to reduce the biological dose to less than 0.5-mrem/hr during operation. The main source of the biological dose is the photons and the neutrons generated by interactions of leaked electrons from the electron gun and accelerator sections with the surrounding concrete and accelerator materials. The Monte Carlo code MCNPX serves as the calculation tool for the shield design, due to its capability to transport electrons, photons, and neutrons coupled problems. The direct photon dose can be tallied by MCNPX calculation, starting with the leaked electrons. However, it is difficult to accurately tally the neutron dose directly from the leaked electrons. The neutron yield per electron from the interactions with the surrounding components is less than 0.01 neutron per electron. This causes difficulties for Monte Carlo analyses and consumes tremendous computation time for tallying with acceptable statistics the neutron dose outside the shield boundary. To avoid these difficulties, the SOURCE and TALLYX user subroutines of MCNPX were developed for the study. The generated neutrons are banked, together with all related parameters, for a subsequent MCNPX calculation to obtain the neutron and secondary photon doses. The weight windows variance reduction technique is utilized for both neutron and photon dose calculations. Two shielding materials, i.e., heavy concrete and ordinary concrete, were considered for the shield design. The main goal is to maintain the total

  17. Windowless gas targets for neutron production

    NASA Astrophysics Data System (ADS)

    Iverson, Erik B.

    A windowless deuterium gas target has been constructed for high yield production of either monoenergetic or white fast neutrons. The operation of this target has been demonstrated on a 900 keV deuteron accelerator. The target is capable of operation at 100 mbar target pressure, and can admit a low duty factor beam of 5 mm transverse extent. The target employs an intermittent valve arrangement to reduce the flow rates in the higher pressure stages of a differentially pumped vacuum system. This valve allows operation at much greater target pressures for low duty factor beams than would otherwise be the case. Neutron yield measurements validated the functionality of the target system. This target will make possible considerable advances in methods of non-destructive testing and evaluation which employ fast neutrons, whether mono-energetic or otherwise. It is further suited to use as a thermal neutron source, with the addition of an appropriate moderator. The development of this target system has not only provided a functioning and valuable piece of equipment for use in further research, but has also investigated the technological limitations and functional requirements of implementing such a system in a practical setting. (Copies available exclusively from MIT Libraries, Rm. 14- 0551, Cambridge, MA 2139-4307. Ph. 617-253-5668; Fax 617- 253-1690.)

  18. Particle acceleration in axisymmetric, magnetized neutron stars

    NASA Technical Reports Server (NTRS)

    Baker, K. B.; Sturrock, P. A.

    1977-01-01

    The potential drop in the polar cap region of a rotating, magnetized neutron star is found assuming that the magnetic field is dipolar, with the field aligned (or anti-aligned) with the rotation axis. The curvature of the field lines is of critical importance. Charge flow is assumed to be along magnetic field lines. The electric field has a maximum at radius 1.5 R and the magnitude and functional form of the current is determined.

  19. A Sealed-Accelerator-Tube Neutron Generator for Boron Neutron Capture Therapy Application

    SciTech Connect

    Leung, K.-N.; Leung, K.N.; Lee, Y.; Verbeke, J.M.; Vurjic, J.; Williams, M.D.; Wu, L.K.; Zahir, N.

    1998-06-01

    Radio-frequency (RF) driven ion sources are being developed in Lawrence Berkeley National Laboratory (LBNL) for sealed-accelerator-tube neutron generator applications. By using a 2.5-cm-diameter RF-driven multicusp source and a computer designed 100 keV accelerator column, peak extractable hydrogen current exceeding 1 A from a 3-mm-diameter aperture, together with H{sup +} yields over 94% have been achieved. These experimental findings together with recent moderator design will enable one to develop compact 14 MeV neutron generators based on the D-T fusion reaction. In this new neutron generator, the ion source, the accelerator and the target are all housed in a sealed metal container without pumping. With a 120 keV and 1 A deuteron beam, it is estimated that a treatment time of {approx} 45 minutes is needed for boron neutron capture therapy.

  20. Fusion-neutron measurements for magnetized liner inertial fusion experiments on the Z accelerator

    DOE PAGESBeta

    Hahn, K. D.; Chandler, G. A.; Ruiz, C. L.; Cooper, G. W.; Gomez, M. R.; Slutz, S.; Sefkow, A. B.; Sinars, D. B.; Hansen, S. B.; Knapp, P. F.; et al

    2016-05-01

    Several magnetized liner inertial fusion (MagLIF) experiments have been conducted on the Z accelerator at Sandia National Laboratories since late 2013. Measurements of the primary DD (2.45 MeV) neutrons for these experiments suggest that the neutron production is thermonuclear. Primary DD yields up to 3e12 with ion temperatures ~2-3 keV have been achieved. Measurements of the secondary DT (14 MeV) neutrons indicate that the fuel is significantly magnetized. Measurements of down-scattered neutrons from the beryllium liner suggest ρRliner ~ 1g/cm2. Neutron bang times, estimated from neutron time-of-flight (nTOF) measurements, coincide with peak x-ray production. Furthermore, plans to improve and expandmore » the Z neutron diagnostic suite include neutron burn-history diagnostics, increased sensitivity and higher precision nTOF detectors, and neutron recoil-based yield and spectral measurements.« less

  1. Los Alamos Neutron Science Center (LANSCE) accelerator timing system upgrade

    SciTech Connect

    Rybarcyk, L.J.; Shelley, F.E. Jr.

    1997-10-01

    The Los Alamos Neutron Science Center (LANSCE) 800 MeV proton linear accelerator (linac) operates at a maximum repetition rate of twice the AC power line frequency, i.e. 120 Hz. The start of each machine cycle occurs a fixed delay after each zero-crossing of the AC line voltage. Fluctuations in the AC line frequency and phase are therefore present on all linac timing signals. Proper beam acceleration along the linac requires that the timing signals remain well synchronized to the AC line. For neutron chopper spectrometers, e.g., PHAROS at the Manuel Lujan Jr. Neutron Scattering Center, accurate neutron energy selection requires that precise synchronization be maintained between the beam-on-target arrival time and the neutron chopper rotor position. This is most easily accomplished when the chopper is synchronized to a stable, fixed frequency signal. A new zero-crossing circuit which employs a Phase-Locked Loop (PLL) has been developed to increase the phase and frequency stability of the linac timing signals and thereby improve neutron chopper performance while simultaneously maintaining proper linac operation. Results of timing signal data analysis and modeling and a description of the PLL circuit are presented.

  2. Measurements of fusion neutrons from Magnetized Liner Inertial Fusion Experiments on the Z accelerator

    NASA Astrophysics Data System (ADS)

    Hahn, K. D.; Chandler, G. A.; Ruiz, C. L.; Gomez, M. R.; Slutz, S. A.; Sefkow, A. B.; Sinars, D. B.; Hansen, S. B.; Knapp, P. F.; Schmit, P. F.; Harding, E. C.; Awe, T. J.; Torres, J. A.; Jones, B.; Bur, J. A.; Cooper, G. W.; Styron, J. D.; Glebov, V. Yu.

    2015-11-01

    Strong evidence of thermonuclear neutron production has been observed during Magnetized Liner Inertial Fusion (MagLIF) experiments on the Z accelerator. So far, these experiments have utilized deuterium fuel and produced primary DD fusion neutron yields up to 2e12 with electron and ion stagnation temperatures in the 2-3 keV range. We present MagLIF neutron measurements and compare to other data and implosion simulations. In addition to primary DD and secondary DT yields and ion temperatures, other complex physics regarding the degree of fuel magnetization and liner density are elucidated by the neutron measurements. Neutron diagnostic development for deuterium and future deuterium-tritium fuel experiments are also discussed. Sandia is sponsored by the U.S. DOE's NNSA under contract DE-AC04-94AL85000.

  3. Preliminary earth berm shielding calculations for the accelerator production of tritium 1700-MeV accelerator

    SciTech Connect

    Court, J.D.; Pitcher, E.J.; Ferguson, P.D.; Russell, G.J.; Patton, B.W.

    1998-07-01

    The authors have performed calculations using the LAHET Code System (LCS) to obtain an estimation of the amount of earth berm shielding that will be required for the 1700-MeV proton accelerator proposed for the Accelerator Production of Tritium (APT) Project. A source scenario of 10 nA/m beam loss along the beam line was used to calculate the dose values above a 6-m earth berm from high-energy neutrons, low-energy neutrons, and photons. LAHET, a Monte Carlo based particle transport code, was used to transport a 1700-MeV protons from the beam along a divergence path of 1{degree} from the original beam direction and impacting representative beampipe material along a 300-m beamline. LAHET was then used to track all high-energy neutron production until the neutrons either escape the berm shield, or scatter down in energy to 20 MeV, where their parameters were then written to a source file for MCNP. Photon production data was also written to a source file used by MCNP. MCNP transported all neutrons and photons from the LAHET source file until they (1) were absorbed, scattered down to an energy cutoff, or (2) escaped from the system. Doses were calculated from surface flux tallies obtained from LAHET and MCNP. These doses were then compared to earlier Moyer model calculations.

  4. Conceptual design of an RFQ accelerator-based neutron source for boron neutron-capture therapy

    SciTech Connect

    Wangler, T.P.; Stovall, J.E.; Bhatia, T.S.; Wang, C.K.; Blue, T.E.; Gahbauer, R.A.

    1989-01-01

    We present a conceptual design of a low-energy neutron generator for treatment of brain tumors by boron neutron capture theory (BNCT). The concept is based on a 2.5-MeV proton beam from a radio-frequency quadrupole (RFQ) linac, and the neutrons are produced by the /sup 7/Li(p,n)/sup 7/Be reaction. A liquid lithium target and modulator assembly are designed to provide a high flux of epithermal neutrons. The patient is administered a tumor-specific /sup 10/Be-enriched compound and is irradiated by the neutrons to create a highly localized dose from the reaction /sup 10/B(n,..cap alpha..)/sup 7/Li. An RFQ accelerator-based neutron source for BNCT is compact, which makes it practical to site the facility within a hospital. 11 refs., 5 figs., 1 tab.

  5. Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method

    DOEpatents

    Yoon, Woo Y.; Jones, James L.; Nigg, David W.; Harker, Yale D.

    1999-01-01

    A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0.times.10.sup.9 neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use.

  6. Accelerator-based neutron source for boron neutron capture therapy (BNCT) and method

    DOEpatents

    Yoon, W.Y.; Jones, J.L.; Nigg, D.W.; Harker, Y.D.

    1999-05-11

    A source for boron neutron capture therapy (BNCT) comprises a body of photoneutron emitter that includes heavy water and is closely surrounded in heat-imparting relationship by target material; one or more electron linear accelerators for supplying electron radiation having energy of substantially 2 to 10 MeV and for impinging such radiation on the target material, whereby photoneutrons are produced and heat is absorbed from the target material by the body of photoneutron emitter. The heavy water is circulated through a cooling arrangement to remove heat. A tank, desirably cylindrical or spherical, contains the heavy water, and a desired number of the electron accelerators circumferentially surround the tank and the target material as preferably made up of thin plates of metallic tungsten. Neutrons generated within the tank are passed through a surrounding region containing neutron filtering and moderating materials and through neutron delimiting structure to produce a beam or beams of epithermal neutrons normally having a minimum flux intensity level of 1.0{times}10{sup 9} neutrons per square centimeter per second. Such beam or beams of epithermal neutrons are passed through gamma ray attenuating material to provide the required epithermal neutrons for BNCT use. 3 figs.

  7. ITEP subcritical neutron generator driven by charged particle accelerator

    SciTech Connect

    Shvedov, Oleg V.; Chuvilo, Ivan V.; Kulikov, Evgeny V.; Vasiliev, Valery V.; Igumnov, Mikhail M.; Kozodaev, Alexander M.; Volkov, Evgeny B.; Lopatkin, Alexander V.

    1995-09-15

    A research facility prototype including a combination of a linear accelerator, a neutron generating target, a subcritical multiplying system is discussed. Principles of the nuclear safety ensuring and means of its attainment for Subcritical Neutron Generator are considered. The scheme of the multiplying is shown. The assembly will be mounted in the body of the partly dismantled ITEP HWR. Requirements for subcritical assembly are worked out and their feasibility within the framework of the heavy-water blanket is shown. The facility's application as a full-scale model of more powerful installations of this kind and for fundamental experimental research has been investigated.

  8. Optimization of an accelerator-based epithermal neutron source for neutron capture therapy

    SciTech Connect

    Kononov, O.E.; Kononov, V.N.; Bokhovko, M.V.; Korobeynikov, V.V.; Soloviev, A.N.; Chu, W.T.

    2004-02-20

    A modeling investigation was performed to choose moderator material and size for creating optimal epithermal neutron beams for BNCT based on a proton accelerator and the 7Li(p,n)7Be reaction as a neutrons source. An optimal configuration is suggested for the beam shaping assembly made from polytetrafluoroethylene and magnesium fluorine. Results of calculation were experimentally tested and are in good agreement with measurements.

  9. COMMISSIONING OF THE SPALLATION NEUTRON SOURCE ACCELERATOR SYSTEMS

    SciTech Connect

    Plum, Michael A

    2007-01-01

    The Spallation Neutron Source accelerator complex consists of a 2.5 MeV H- front-end injector system, a 186 MeV normal-conducting linear accelerator, a 1 GeV superconducting linear accelerator, an accumulator ring, and associated beam transport lines. The linac was commissioned in five discrete runs, starting in 2002 and completed in 2005. The accumulator ring and associated beam transport lines were commissioned in two runs from January to April 2006. With the completed commissioning of the SNS accelerator, the facility has begun initial low-power operations. In the course of beam commissioning, most beam performance parameters and beam intensity goals have been achieved at low duty factor. A number of beam dynamics measurements have been performed, including emittance evolution, transverse coupling in the ring, beam instability thresholds, and beam distributions on the target. The commissioning results, achieved beam performance and initial operating experience of the SNS will be discussed

  10. Ion Acceleration by Magnetic Pinch Instabilities- Powerful Neutron Sources

    NASA Astrophysics Data System (ADS)

    Hayes, Anna; Li, Hui

    2014-10-01

    Since the 1950s pinch discharges with deuterium gas have been known to produce large neutron bursts. During these early quests for laboratory fusion it was initially believed that the heat produced in the pinch led to sufficently high temperatures that these neutrons resulted from thermonuclear (TN) burn. However, a series of careful measurements led by Stirling Colgate was carried out to show that these neutrons did not result form TN burn. Rather, they resulted from an m = 0 sausage mode instability that accelerated the ions, causing beam-target interactions. Today, this same mechanism is used in dense plasma focus machines to generate intense neutron pulses for neutron activation experiments. One such experiment, to test the citicality of aging plutonium, is currently being planned at the Nevada Test Site. Helping to characterize the neutrons from the dense palsma focus to be used in this large experiment was the last applied physics project that Stirling work on. In this talk we will summarize the physics issues involved both in the original discovery in the 1950s and in today's experiments.

  11. Accelerator based epithermal neutron source for neutron capture therapy. Annual report, [October 1990--April 1991

    SciTech Connect

    Brugger, R.; Kunze, J.

    1991-05-01

    Several investigators have suggested that a charged particle accelerator with light element reactions might be able to produce enough epithermal neutrons to be useful in Neutron Capture Therapy. The reaction choice so far has been the Li(p,n) reaction with protons up to 2.5 MeV. A moderator around the target would reduce the faster neutrons down to the epithermal energy region. The goals of the present research are: identify better reactions; improve the moderators; and find better combinations of 1 and 2. The target is to achieve, at the patient location, an epithermal neutron current of greater than 10{sup 9}n/cm{sup 2}sec, with a dose to tissue from the neutrons alone of less than 10{sup {minus}10} rads/n and a dose from the gamma rays in the beam of less than 10{sup {minus}10} rads/n.

  12. A neutron producing target for BINP accelerator-based neutron source.

    PubMed

    Bayanov, B; Kashaeva, E; Makarov, A; Malyshkin, G; Samarin, S; Taskaev, S

    2009-07-01

    An innovative accelerator-based neutron source for BNCT has just started operation at the Budker Institute of Nuclear Physics, Novosibirsk. One of the main elements of the facility is a lithium target producing neutrons via the threshold (7)Li(p,n)(7)Be reaction at 25 kW proton beam with energies of 1.915 MeV or 2.5 MeV. The design of an optimal target and results of the investigation of radiation blistering of the lithium layer were presented at previous NCT Congresses. During the last two years the neutron target has been manufactured, assembled and placed in the facility. Optimization of the target is carried out with the Monte Carlo simulation code MCNP. In this article, the design of the target is discussed, results of all previous investigations are summarized, results of target testing and neutron generation are described, and results of simulation of neutron spectra are presented. PMID:19376729

  13. Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy

    SciTech Connect

    Herrera, Maria S.; Gonzalez, Sara J.; Minsky, Daniel M.; Kreiner, Andres J.

    2010-08-04

    Glioblastoma multiforme and metastatic melanoma are frequent brain tumors in adults and presently still incurable diseases. Boron Neutron Capture Therapy (BNCT) is a promising alternative for this kind of pathologies. Accelerators have been proposed for BNCT as a way to circumvent the problem of siting reactors in hospitals and for their relative simplicity and lower cost among other advantages. Considerable effort is going into the development of accelerator-based BNCT neutron sources in Argentina. Epithermal neutron beams will be produced through appropriate proton-induced nuclear reactions and optimized beam shaping assemblies. Using these sources, computational dose distributions were evaluated in a real patient with diagnosed glioblastoma treated with BNCT. The simulated irradiation was delivered in order to optimize dose to the tumors within the normal tissue constraints. Using Monte Carlo radiation transport calculations, dose distributions were generated for brain, skin and tumor. Also, the dosimetry was studied by computing cumulative dose-volume histograms for volumes of interest. The results suggest acceptable skin average dose and a significant dose delivered to tumor with low average whole brain dose for irradiation times less than 60 minutes, indicating a good performance of an accelerator-based BNCT treatment.

  14. Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy

    NASA Astrophysics Data System (ADS)

    Herrera, María S.; González, Sara J.; Minsky, Daniel M.; Kreiner, Andrés J.

    2010-08-01

    Glioblastoma multiforme and metastatic melanoma are frequent brain tumors in adults and presently still incurable diseases. Boron Neutron Capture Therapy (BNCT) is a promising alternative for this kind of pathologies. Accelerators have been proposed for BNCT as a way to circumvent the problem of siting reactors in hospitals and for their relative simplicity and lower cost among other advantages. Considerable effort is going into the development of accelerator-based BNCT neutron sources in Argentina. Epithermal neutron beams will be produced through appropriate proton-induced nuclear reactions and optimized beam shaping assemblies. Using these sources, computational dose distributions were evaluated in a real patient with diagnosed glioblastoma treated with BNCT. The simulated irradiation was delivered in order to optimize dose to the tumors within the normal tissue constraints. Using Monte Carlo radiation transport calculations, dose distributions were generated for brain, skin and tumor. Also, the dosimetry was studied by computing cumulative dose-volume histograms for volumes of interest. The results suggest acceptable skin average dose and a significant dose delivered to tumor with low average whole brain dose for irradiation times less than 60 minutes, indicating a good performance of an accelerator-based BNCT treatment.

  15. Laser Acceleration of Ultrashort Ion Bunches and Femtosecond Neutron Sources

    SciTech Connect

    Macchi, A.; Cattani, F.; Liseykina, T. V.; Cornolti, F.

    2006-04-07

    We have theoretically investigated the acceleration of ions in the interaction of high intensity, circularly polarized laser pulses with overdense plasmas. By using 1D and 2D particle-in-cell (PIC) simulations we find that high-density, short duration ion bunches moving into the plasma are promptly generated at the laser-plasma interaction surface. This regime is qualitatively different from ion acceleration regimes driven by fast electrons, such as sheath acceleration at the back of the target or shock acceleration at the front, which occur for linear polarization. A simple analytical model accounts for the numerical observations and provides scaling laws for the ion bunch velocity and generation time as a function of pulse intensity and plasma density. The present mechanism based on circular polarization of the laser pulse leads to moderate ion energies (in the 100 keV-1 MeV range) but very high ion densities and low beam divergence. These ion bunches might be of interest for problems of compression and acceleration of high-density matter by short pulses as well as for the development of compact neutron sources. We analyzed a scheme based on two-side irradiation of a thin foil deuterated target, where two colliding ion bunches are produced leading to an ultrashort neutron burst. We evaluated that, for intensities of a few 1019 W cm-2, more than 103 neutrons per Joule may be produced within a time shorter than one femtosecond. Another scheme based on a layered deuterium-tritium target is outlined.

  16. Burn-up and neutron economy of accelerator-driven reactor

    SciTech Connect

    Takahashi, H.; Yang, W.; An, Y.; Yamazaki, Y.

    1997-07-01

    It is desirable to have only a small reactivity change in the large burn-up of a solid fuel fast reactor, so that the number of replacements or shuffling of the fuel can be reduced, and plant factor accordingly increased. Also, this reduces the number of control rods needed for the change in burn-up reactivity. In subcritical operation, power controlled by beam power is suggested, but this practice is not as economical as the use of control rods and makes more careful operation of the accelerator is required due to changes in the wake field. In subcritical operation, even a slightly subcritical one, the safety problems associated with a hard neutron spectrum can be alleviated. Neutron leakage from a flattened core, which is needed for operation of the critical fast reactor can be lessen by using the non flat core which has good neutron economy. For generating nuclear energy, it is essential to have a high neutron economy, although breeding the fuel is not welcomed in the present political climate, as is needed for transmuting long lived fission products. In contrast to the breeder, the accelerator driven reactor can separate the energy production from fuel production and processing. Thus, it is suited for non-proliferation of nuclear material by prohibiting the processing and production of fuel in the unrestricted area so this can be only done in international controlled areas which are restricted and remote.

  17. SEARCH FOR SUBTHRESHOLD NEUTRON PRODUCTION IN BE

    SciTech Connect

    CHRIEN,R.E.; ALBURGER,D.E.; SUTTER,R.J.; WISHART,J,F,

    2004-09-27

    We have searched for neutrons from the 3-body photon-induced reaction {sup 9}Be + {gamma} {yields} {alpha} + {alpha} + n using bremsstrahlung produced by electrons from a 2-MV Van de Graaff. The target was located within a block of beryllium surrounded by an array of {sup 3}He proportional counters embedded in paraffin. Based on energy and intensity calibrations of the accelerator and detector using the {sup 9}Be + {gamma} {yields} {sup 8}Be + n reaction, an upper limit of 93 nb (4{sigma}) was placed on the cross section for neutron production between the 3-body and 2-body thresholds. This value is substantially below a previously experimental result using photoexcitation by a {sup 142}Pr gamma source and also below an earlier theoretical estimate. We suggest that bremsstrahlung due to beta rays between 1665 keV and the 2160-keV end-point of the {sup 142}Pr beta-ray spectrum could account for the photoneutron yield in the 3-body region that had previously been attributed to {sup 142}Pr gamma rays.

  18. Accelerator Production of Tritium Programmatic Environmental Impact Statement Input Submittal

    SciTech Connect

    Miller, L.A.; Greene, G.A.; Boyack, B.E.

    1996-02-01

    The Programmatic Environmental Impact Statement for Tritium Supply and Recycling considers several methods for the production of tritium. One of these methods is the Accelerator Production of Tritium. This report summarizes the design characteristics of APT including the accelerator, target/blanket, tritium extraction facility, and the balance of plant. Two spallation targets are considered: (1) a tungsten neutron-source target and (2) a lead neutron-source target. In the tungsten target concept, the neutrons are captured by the circulating He-3, thus producing tritium; in the lead target concept, the tritium is produced by neutron capture by Li-6 in a surrounding lithium-aluminum blanket. This report also provides information to support the PEIS including construction and operational resource needs, waste generation, and potential routine and accidental releases of radioactive material. The focus of the report is on the impacts of a facility that will produce 3/8th of the baseline goal of tritium. However, some information is provided on the impacts of APT facilities that would produce smaller quantities.

  19. Designing accelerator-based epithermal neutron beams for boron neutron capture therapy

    SciTech Connect

    Bleuel, D.L.; Donahue, R.J.; Ludewigt, B.A.; Vujic, J.

    1998-09-01

    The {sup 7}Li(p,n){sup 7}Be reaction has been investigated as an accelerator-driven neutron source for proton energies between 2.1 and 2.6 MeV. Epithermal neutron beams shaped by three moderator materials, Al/AlF{sub 3}, {sup 7}LiF, and D{sub 2}O, have been analyzed and their usefulness for boron neutron capture therapy (BNCT) treatments evaluated. Radiation transport through the moderator assembly has been simulated with the Monte Carlo {ital N}-particle code (MCNP). Fluence and dose distributions in a head phantom were calculated using BNCT treatment planning software. Depth-dose distributions and treatment times were studied as a function of proton beam energy and moderator thickness. It was found that an accelerator-based neutron source with Al/AlF{sub 3} or {sup 7}LiF as moderator material can produce depth-dose distributions superior to those calculated for a previously published neutron beam design for the Brookhaven Medical Research Reactor, achieving up to {approximately}50{percent} higher doses near the midline of the brain. For a single beam treatment, a proton beam current of 20 mA, and a {sup 7}LiF moderator, the treatment time was estimated to be about 40 min. The tumor dose deposited at a depth of 8 cm was calculated to be about 21 Gy-Eq. {copyright} {ital 1998 American Association of Physicists in Medicine.}

  20. Recent performance of the Intense Pulsed Neutron Source accelerator system

    SciTech Connect

    Potts, C.; Brumwell, F.; Rauchas, A.; Stipp, V.; Volk, G.; Donley, L.

    1987-03-01

    The Intense Pulsed Neutron Source (IPNS) accelerator system has now been in operation as part of a national user program for over five years. During that period steady progress has been made in both beam intensity and reliability. Almost 1.8 billion pulses totaling 4 x 10/sup 21/ protons have now been delivered to the spallation neutron target. Recent weekly average currents have reached 15 ..mu..A (3.2 x 10/sup 12/ protons per pulse, 30 pulses per second) and short-term peaks of almost 17 ..mu..A have been reached. In fact, the average current for the last two years is up 31% over the average for the first three years of operation.

  1. A high power accelerator driver system for spallation neutron sources

    SciTech Connect

    Jason, A.; Blind, B.; Channell, P.

    1996-07-01

    This is the final report of a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). For several years, the Los Alamos Meson Physics Facility (LAMPF) and the Proton Storage Ring (PSR) have provided a successful driver for the nearly 100-kW Los Alamos Neutron Scattering Center (LANSCE) source. The authors have studied an upgrade to this system. The goal of this effort was to establish a credible design for the accelerator driver of a next-generation source providing 1-MW of beam power. They have explored a limited subset of the possible approaches to a driver and have considered only the low 1-MW beam power. The next-generation source must utilize the optimum technology and may require larger neutron intensities than they now envision.

  2. Multileaf shielding design against neutrons produced by medical linear accelerators.

    PubMed

    Rebello, W F; Silva, A X; Facure, A

    2008-01-01

    This work aims at presenting a study using Monte Carlo simulation of a Multileaf Shielding (MLS) System designed to be used for the protection of patients who undergo radiotherapy treatment, against undesired exposure to neutrons produced in the components of the medical linear accelerator heads. The choice of radiotherapy equipment as the subject of study fell on the Varian Clinac 2,100/2,300 with MLC-120 operating at 18 MeV. The general purpose Monte Carlo N-Particle radiation transport code, MCNP5, was used in the computer simulation in order to determine the ambient dose equivalent, H (10), on several points on the patient's plane, with the equipment operation with and without the MLS. The results of the simulations showed a significant neutron dose reduction after the inclusion of the proposed shielding. PMID:17569690

  3. Beam intensity increases at the intense pulsed neutron source accelerator

    SciTech Connect

    Potts, C.; Brumwell, F.; Norem, J.; Rauchas, A.; Stipp, V.; Volk, G.

    1985-01-01

    The Intense Pulsed Neutron Source (IPNS) accelerator system has managed a 40% increase in time average beam current over the last two years. Currents of up to 15.6..mu..A (3.25 x 10/sup 12/ protons at 30 Hz) have been successfully accelerated and cleanly extracted. Our high current operation demands low loss beam handling to permit hands-on maintenance. Synchrotron beam handling efficiencies of 90% are routine. A new H/sup -/ ion source which was installed in March of 1983 offered the opportunity to get above 8 ..mu..A but an instability caused unacceptable losses when attempting to operate at 10 ..mu..A and above. Simple techniques to control the instabilities were introduced and have worked well. These techniques are discussed below. Other improvements in the regulation of various power supplies have provided greatly improved low energy orbit stability and contributed substantially to the increased beam current.

  4. Accelerator Production Options for 99MO

    SciTech Connect

    Bertsche, Kirk; /SLAC

    2010-08-25

    Shortages of {sup 99}Mo, the most commonly used diagnostic medical isotope, have caused great concern and have prompted numerous suggestions for alternate production methods. A wide variety of accelerator-based approaches have been suggested. In this paper we survey and compare the various accelerator-based approaches.

  5. Neutron dosimetry in linear electron accelerator during radiotherapy treatment: simulation and experiment

    NASA Astrophysics Data System (ADS)

    Manfredotti, Claudio; Nastasi, U.; Ongaro, C.; Stasi, E.; Zanini, Alessandro

    1995-03-01

    In the electron linear accelerators used for radiotherapy by high energy electrons or gamma rays, there is a non negligible production of neutrons by photodisintegration or electrodisintegration reactions on the high Z components of the head machine (target, flattening filter, collimators). At the Experimental Physics Department of Torino University, Torino, Italy an experimental and theoretical evaluation has been performed on the undesired neutron production in the MD Class Mevatron Siemens accelerator used at the Radiotherapy Department of S. Giovanni Battista A.S. Hospital for cancer therapy by a 15 MV gamma ray beam. A simulation of the total process has been carried out, using EGS4 MonteCarlo computer code for the evaluation of photoneutron spectra and MCNP code for the neutron transport in the patient's body. The geometrical description both of the accelerator head in EGS4 and of the anthropomorphous phantom in MCNP have been highly optimized. Experimental measurements have been carried out by bubble detectors BD 100R appropriately allocated inside a new phantom in polyetylene and plexiglass, especially designed for this purpose.

  6. High-Current Experiments for Accelerator-Based Neutron Capture Therapy Applications

    SciTech Connect

    Gierga, D.P.; Klinkowstein, R.E.; Hughey, B.H.; Shefer, R.E.; Yanch, J.C.; Blackburn, B.W.

    1999-06-06

    Several accelerator-based neutron capture therapy applications are under development. These applications include boron neutron capture therapy for glioblastoma multiform and boron neutron capture synovectomy (BNCS) for rheumatoid arthritis. These modalities use accelerator-based charged-particle reactions to create a suitable neutron source. Neutrons are produced using a high-current, 2-MV terminal tandem accelerator. For these applications to be feasible, high accelerator beam currents must be routinely achievable. An effort was undertaken to explore the operating regime of the accelerator in the milliampere range. In preparation for high-current operation of the accelerator, computer simulations of charged-particle beam optics were performed to establish high-current operating conditions. Herein we describe high beam current simulations and high beam current operation of the accelerator.

  7. Understanding neutron production in the deuterium dense plasma focus

    SciTech Connect

    Appelbe, Brian E-mail: j.chittenden@imperial.ac.uk; Chittenden, Jeremy E-mail: j.chittenden@imperial.ac.uk

    2014-12-15

    The deuterium Dense Plasma Focus (DPF) can produce copious amounts of MeV neutrons and can be used as an efficient neutron source. However, the mechanism by which neutrons are produced within the DPF is poorly understood and this limits our ability to optimize the device. In this paper we present results from a computational study aimed at understanding how neutron production occurs in DPFs with a current between 70 kA and 500 kA and which parameters can affect it. A combination of MHD and kinetic tools are used to model the different stages of the DPF implosion. It is shown that the anode shape can significantly affect the structure of the imploding plasma and that instabilities in the implosion lead to the generation of large electric fields at stagnation. These electric fields can accelerate deuterium ions within the stagnating plasma to large (>100 keV) energies leading to reactions with ions in the cold dense plasma. It is shown that the electromagnetic fields present can significantly affect the trajectories of the accelerated ions and the resulting neutron production.

  8. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy

    PubMed Central

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 105 n/cm2/s with sufficient accuracy. The SOF detector will be useful for phantom experiments with BNCT neutron fields from low-current accelerator-based neutron sources. PMID:25589504

  9. Radiation effects in materials for accelerator-driven neutron technologies. Revision

    SciTech Connect

    Wechsler, M.S.; Lin, C.; Sommer, W.F.

    1997-04-01

    Accelerator-driven neutron technologies use spallation neutron sources (SNS`s) in which high-energy protons bombard a heavy-element target and spallation neutrons are produced. The materials exposed to the most damaging radiation environments in an SNS are those in the path of the incident proton beam. This includes target and window materials. These materials will experience damage from the incident protons and the spallation neutrons. In addition, some materials will be damaged by the spallation neutrons alone. The principal materials of interest for SNS`s are discussed elsewhere. The target should consist of one or more heavy elements, so as to increase the number of neutrons produced per incident proton. A liquid metal target (e.g., Pb, Bi, Pb-Bi, Pb-Mg, and Hg) has the advantage of eliminating the effects of radiation damage on the target material itself, but concerns over corrosion problems and the influence of transmutants remain. The major solid targets in operating SNS`s and under consideration for the 1-5 MW SNS`s are W, U, and Pb. Tungsten is the target material at LANSCE, and is the projected target material for an upgraded LANSCE target that is presently being designed. It is also the projected target material for the tritium producing SNS under design at LANL. In this paper, the authors present the results of spallation radiation damage calculations (displacement and He production) for tungsten.

  10. Accelerator requirements for fast-neutron interrogation of luggage and cargo

    SciTech Connect

    Micklich, B.J.; Fink, C.L.; Yule, T.J.

    1995-05-01

    Several different fast-neutron based techniques are being studied for the detection of contraband substances in luggage and cargo containers. The present work discusses the accelerator requirements for fast-neutron transmission spectroscopy (FNTS), pulsed fast-neutron analysis (PFNA), and 14-MeV neutron interrogation. These requirements are based on the results of Monte-Carlo simulations of neutron or gamma detection rates. Accelerator requirements are driven by count-rate considerations, spatial resolution and acceptable uncertainties in elemental compositions. The authors have limited their analyses to luggage inspection with FNTS and to cargo inspection with PFNA or 14-MeV neutron interrogation.

  11. Measurements of photo-neutrons from a medical linear accelerator using CR-39 plastic nuclear track detectors

    NASA Astrophysics Data System (ADS)

    Monson, Jonathan Michael

    Photo-neutrons are produced when x-ray energies exceed 7 MeV. Photo-neutron production varies depending on x-ray beam energy. CR-39 PNTDs were used in this study to measure the neutron absorbed dose and dose equivalent produced by a Varian Clinac 23EX for x-ray beams of 6 and 18 MVp and with a Varian Trilogy using an x-ray beam of 10 MVp. Neutron absorbed dose and dose equivalent were measured at 100 cm SSD at 0, 20, and 40 cm off-axis from the primary beam in air. Using a polyethylene phantom the neutron absorbed dose and dose equivalent were measured at 100 cm SSD from the top of the phantom at 0, 5, and 10 cm from the surface, in the beam central axis and off-axis distances of 20 and 40 cm at a depth of 10 cm. The neutron absorbed dose and dose equivalent from medical linear accelerators have been measured from the LET spectrum of recoiled tracks produced in the CR-39 PNTDs for high energy neutrons (1-20 MeV) and the neutron dose equivalent for low energy (< 1 MeV) neutrons were measured using TRNDs. In this study, the experimentally measured absorbed dose and dose equivalent from photo-neutrons produced in a common medical linear accelerator operating at energies 10 and 18 MVp range from 0.2 microGy n/Gyx and 2 microSv n/Gyx to 495 microGy n/Gyx and 5500 microSv n/Gyx respectively. The neutron absorbed dose for the 6 MVp x-ray beam was measured to be 0 microGyn/Gyx. Low energy neutrons accounted for less than 1% of the neutron dose equivalent. Those detectors exposed inside of the phantom measured a higher contribution from high LET (> 100 keV/microm) particles than those detectors exposed in air.

  12. Improved Actinide Neutron Capture Cross Sections Using Accelerator Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Bauder, W.; Pardo, R. C.; Kondev, F. G.; Kondrashev, S.; Nair, C.; Nusair, O.; Palchan, T.; Scott, R.; Seweryniak, D.; Vondrasek, R.; Collon, P.; Paul, M.; Youinou, G.; Salvatores, M.; Palmotti, G.; Berg, J.; Maddock, T.; Imel, G.

    2014-09-01

    The MANTRA (Measurement of Actinide Neutron TRAnsmutations) project will improve energy-integrated neutron capture cross section data across the actinide region. These data are incorporated into nuclear reactor models and are an important piece in understanding Generation IV reactor designs. We will infer the capture cross sections by measuring isotopic ratios from actinide samples, irradiated in the Advanced Test Reactor at INL, with Accelerator Mass Spectrometry (AMS) at ATLAS (ANL). The superior sensitivity of AMS allows us to extract multiple cross sections from a single sample. In order to analyze the large number of samples needed for MANTRA and to meet the goal of extracting multiple cross sections per sample, we have made a number of modifications to the AMS setup at ATLAS. In particular, we are developing a technique to inject solid material into the ECR with laser ablation. With laser ablation, we can better control material injection and potentially increase efficiency in the ECR, thus creating less contamination in the source and reducing cross talk. I will present work on the laser ablation system and preliminary results from our AMS measurements. The MANTRA (Measurement of Actinide Neutron TRAnsmutations) project will improve energy-integrated neutron capture cross section data across the actinide region. These data are incorporated into nuclear reactor models and are an important piece in understanding Generation IV reactor designs. We will infer the capture cross sections by measuring isotopic ratios from actinide samples, irradiated in the Advanced Test Reactor at INL, with Accelerator Mass Spectrometry (AMS) at ATLAS (ANL). The superior sensitivity of AMS allows us to extract multiple cross sections from a single sample. In order to analyze the large number of samples needed for MANTRA and to meet the goal of extracting multiple cross sections per sample, we have made a number of modifications to the AMS setup at ATLAS. In particular, we are

  13. Accelerators for Inertial Fusion Energy Production

    NASA Astrophysics Data System (ADS)

    Bangerter, R. O.; Faltens, A.; Seidl, P. A.

    2014-02-01

    Since the 1970s, high energy heavy ion accelerators have been one of the leading options for imploding and igniting targets for inertial fusion energy production. Following the energy crisis of the early 1970s, a number of people in the international accelerator community enthusiastically began working on accelerators for this application. In the last decade, there has also been significant interest in using accelerators to study high energy density physics (HEDP). Nevertheless, research on heavy ion accelerators for fusion has proceeded slowly pending demonstration of target ignition using the National Ignition Facility (NIF), a laser-based facility at Lawrence Livermore National Laboratory. A recent report of the National Research Council recommends expansion of accelerator research in the US if and when the NIF achieves ignition. Fusion target physics and the economics of commercial energy production place constraints on the design of accelerators for fusion applications. From a scientific standpoint, phase space and space charge considerations lead to the most stringent constraints. Meeting these constraints almost certainly requires the use of multiple beams of heavy ions with kinetic energies > 1 GeV. These constraints also favor the use of singly charged ions. This article discusses the constraints for both fusion and HEDP, and explains how they lead to the requirements on beam parameters. RF and induction linacs are currently the leading contenders for fusion applications. We discuss the advantages and disadvantages of both options. We also discuss the principal issues that must yet be resolved.

  14. Evaluation of medical isotope production with the accelerator production of tritium (APT) facility

    SciTech Connect

    Benjamin, R.W.; Frey, G.D.; McLean, D.C., Jr; Spicer, K.M.; Davis, S.E.; Baron, S.; Frysinger, J.R.; Blanpied, G.; Adcock, D.

    1997-07-10

    The accelerator production of tritium (APT) facility, with its high beam current and high beam energy, would be an ideal supplier of radioisotopes for medical research, imaging, and therapy. By-product radioisotopes will be produced in the APT window and target cooling systems and in the tungsten target through spallation, neutron, and proton interactions. High intensity proton fluxes are potentially available at three different energies for the production of proton- rich radioisotopes. Isotope production targets can be inserted into the blanket for production of neutron-rich isotopes. Currently, the major production sources of radioisotopes are either aging or abroad, or both. The use of radionuclides in nuclear medicine is growing and changing, both in terms of the number of nuclear medicine procedures being performed and in the rapidly expanding range of procedures and radioisotopes used. A large and varied demand is forecast, and the APT would be an ideal facility to satisfy that demand.

  15. Sensitivity Upgrades to the Idaho Accelerator Center Neutron Time of Flight Spectrometer

    SciTech Connect

    Thompson, S. J.; Kinlaw, M. T.; Harmon, J. F.; Wells, D. P.; Hunt, A. W.

    2007-10-26

    Past experiments have shown that discrimination between between fissionable and non-fissionable materials is possible using an interrogation technique that monitors for high energy prompt fission neutrons. Several recent upgrades have been made to the neutron time of flight spectrometer at the Idaho Accelerator Center with the intent of increasing neutron detection sensitivity, allowing for system use in nonproliferation and security applications.

  16. Monitoring of D-T accelerator neutron output in a PGNAA system using silicon carbide detectors

    NASA Astrophysics Data System (ADS)

    Dulloo, Abdul R.; Ruddy, Frank H.; Seidel, John G.; Petrović, Bojan

    2001-07-01

    Silicon carbide (SiC) detectors are being employed to monitor the neutron output of the D-T accelerator in a pulsed Prompt Gamma Neutron Activation Analysis (PGNAA) system. Detection of the source neutrons relies on energetic neutron reactions in the detector material. Experimental testing has been performed to confirm that the detector response is caused by fast neutrons from the accelerator source. Modeling calculations have also been carried out to provide additional verification. Use of the SiC detectors in the PGNAA system is expected to assist in evaluating system performance as well as ensuring accurate data interpretation and analysis.

  17. Time extended production of neutrons during a solar flare

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.; Forrest, D. J.; Vestrand, W. T.; Dubrunner, H.; Flueckiger, E. O.; Cooper, J. F.; Kanbach, G.; Reppin, C.; Share, G. H.

    1985-01-01

    The most energetic neutral emissions expected from solar flares are gamma rays (10 MeV) from relativistic primary and secondary electron bremsstrahlung,from approx 0 meson decay, and from neutrons ( 50 MeV). Bremsstrahlung photon energies extend to that of the highest energy electron present, but the shape of the pi sup 0 gamma ray spectrum, peaking at 69 MeV, does not depend strongly on the proton spectrum above threshold, which is approx. 292 MeV for meson production on protons. The highest energy neutrons observed indicate directly the highest energy ions which interact at the Sun, and the presence or absence of anergy cutoff in the acceleration process. The high-energy proton spectrum shape can be determined from the neutron spectrum.

  18. Lithium target for accelerator based BNCT neutron source: Influence by the proton irradiation on lithium

    NASA Astrophysics Data System (ADS)

    Fujii, R.; Imahori, Y.; Nakakmura, M.; Takada, M.; Kamada, S.; Hamano, T.; Hoshi, M.; Sato, H.; Itami, J.; Abe, Y.; Fuse, M.

    2012-12-01

    The neutron source for Boron Neutron Capture Therapy (BNCT) is in the transition stage from nuclear reactor to accelerator based neutron source. Generation of low energy neutron can be achieved by 7Li (p, n) 7Be reaction using accelerator based neutron source. Development of small-scale and safe neutron source is within reach. The melting point of lithium that is used for the target is low, and durability is questioned for an extended use at a high current proton beam. In order to test its durability, we have irradiated lithium with proton beam at the same level as the actual current density, and found no deterioration after 3 hours of continuous irradiation. As a result, it is suggested that lithium target can withstand proton irradiation at high current, confirming suitability as accelerator based neutron source for BNCT.

  19. Radiation effects in materials for accelerator-driven neutron technologies

    SciTech Connect

    Wechsler, M.S.; Lin, C.; Sommer, W.F.; Daemen, L.L.; Ferguson, P.D.

    1997-03-01

    The materials exposed to the most damaging radiation environments in an SNS (spallation neutron source) are those in the path of the incident proton beam. This includes target and window materials. These materials will experience damage from the incident protons and the spallation neutrons. The major solid targets in operating SNS`s and under consideration for the 1--5 MW SNS`s are W, U, and Pb. Tungsten is the target material at LANSCE, and is the project target material for an upgraded LANSCE target that is presently being designed. It is also the projected target material for the tritium producing SNS under design at LANL. In this paper, the authors present the results of spallation radiation damage calculations (displacement and He production) for tungsten.

  20. 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

  1. SU-E-T-543: Measurement of Neutron Activation From Different High Energy Varian Linear Accelerators

    SciTech Connect

    Thatcher, T; Madsen, S; Sudowe, R; Meigooni, A Soleimani

    2015-06-15

    Purpose: Linear accelerators producing photons above 10 MeV may induce photonuclear reactions in high Z components of the accelerator. These liberated neutrons can then activate the structural components of the accelerator and other materials in the beam path through neutron capture reactions. The induced activity within the accelerator may contribute to additional dose to both patients and personnel. This project seeks to determine the total activity and activity per activated isotope following irradiation in different Varian accelerators at energies above 10 MeV. Methods: A Varian 21IX accelerator was used to irradiate a 30 cm × 30 cm × 20 cm solid water phantom with 15 MV x-rays. The phantom was placed at an SSD of 100 cm and at the center of a 20 cm × 20 cm field. Activation induced gamma spectra were acquired over a 5 minute interval after 1 and 15 minutes from completion of the irradiation. All measurements were made using a CANBERRA Falcon 5000 Portable HPGe detector. The majority of measurements were made in scattering geometry with the detector situated at 90° to the incident beam, 30 cm from the side of the phantom and approximately 10 cm from the top. A 5 minute background count was acquired and automatically subtracted from all subsequent measurements. Photon spectra were acquired for both open and MLC fields. Results: Based on spectral signatures, nuclides have been identified and their activities calculated for both open and MLC fields. Preliminary analyses suggest that activities from the activation products in the microcurie range. Conclusion: Activation isotopes have been identified and their relative activities determined. These activities are only gross estimates since efficiencies have not been determined for this source-detector geometry. Current efforts are focused on accurate determination of detector efficiencies using Monte Carlo calculations.

  2. A neutron track etch detector for electron linear accelerators in radiotherapy

    PubMed Central

    Vukovic, Branko; Faj, Dario; Poje, Marina; Varga, Maja; Radolic, Vanja; Miklavcic, Igor; Ivkovic, Ana; Planinic, Josip

    2010-01-01

    Background Electron linear accelerators in medical radiotherapy have replaced cobalt and caesium sources of radiation. However, medical accelerators with photon energies over 10 MeV generate undesired fast neutron contamination in a therapeutic X-ray photon beam. Photons with energies above 10 MeV can interact with the atomic nucleus of a high-Z material, of which the target and the head of an accelerator consist, and lead to the neutron ejection. Results and conclusions. Our neutron dosimeter, composed of the LR-115 track etch detector and boron foil BN-1 converter, was calibrated on thermal neutrons generated in the nuclear reactor of the Josef Stefan Institute (Slovenia), and applied to dosimetry of undesirable neutrons in photon radiotherapy by the linear accelerator 15 MV Siemens Mevatron. Having considered a high dependence of a cross-section between neutron and boron on neutron energy, and broad neutron spectrum in a photon beam, as well as outside the entrance door to maze of the Mevatron, we developed a method for determining the effective neutron detector response. A neutron dose rate in the photon beam was measured to be 1.96 Sv/h. Outside the Mevatron room the neutron dose rate was 0.62 μSv/h. PACS: 87.52. Ga; 87.53.St; 29.40.Wk. PMID:22933893

  3. Conceptual design of thorium-fuelled Mitrailleuse accelerator-driven subcritical reactor using D-Be neutron source

    SciTech Connect

    Kokubo, Y.; Kamei, T.

    2012-07-01

    A distributed accelerator is a charged-particle accelerator that uses a new acceleration method based on repeated electrostatic acceleration. This method offers outstanding benefits not possible with the conventional radio-frequency acceleration method, including: (1) high acceleration efficiency, (2) large acceleration current, and (3) lower failure rate made possible by a fully solid-state acceleration field generation circuit. A 'Mitrailleuse Accelerator' is a product we have conceived to optimize this distributed accelerator technology for use with a high-strength neutron source. We have completed the conceptual design of a Mitrailleuse Accelerator and of a thorium-fuelled subcritical reactor driven by a Mitrailleuse Accelerator. This paper presents the conceptual design details and approach to implementing the subcritical reactor core. We will spend the next year or so on detailed design work, and then will start work on developing a prototype for demonstration. If there are no obstacles in setting up a development organization, we expect to finish verifying the prototype's performance by the third quarter of 2015. (authors)

  4. Tandem mirrors for neutron production

    SciTech Connect

    Doggett, J.N.

    1983-03-31

    Two mirror machine concepts are being studied as early-time, low-cost, neutron-producing devices for testing and demonstrating reactor-relevant fusion technology. The first of these concepts is for a new, small, driven, steady-state, D-T reactor, called the Technology Demonstration Facility (TDF). The second concept is for upgrades to the MFTF-B machine that burn tritium and run for pulse lengths of some hours. Both devices operate in the Kelley mode in order to provide high-wall loadings of 14-MeV neutrons, thereby providing a valuable test bed for reactor-relevant hardware and subsystems. Either one of these devices could be running in the early 1990's with first wall fluxes between 1.4 and 2.0 MW m/sup -2/.

  5. Neutron productions in the fragmentation of relativistic heavy nuclei and formation of a beam of high-energy neutrons

    NASA Astrophysics Data System (ADS)

    Yurevich, V. I.

    2016-03-01

    The production of quasimonoenergetic high-energy neutrons at zero angle (0°) in the spallation of relativistic heavy nuclei is discussed by considering the example of the interaction of lead nuclei with light target nuclei. It is shown that this process can be used to generate a beam of high-energy neutrons at existing heavy ion accelerators. At the same time, itmay lead to the appearance of a parasitic neutron beam because of the interaction of the heavy-ion beam used with beam line and experimental setup materials.

  6. Mobile-accelerator neutron-radiography system. Final report, February 1978-December 1983

    SciTech Connect

    Dance, W.E.; Carollo, S.F.; Bumgardner, H.M.

    1984-10-01

    The use of neutron radiography for the inspection and maintenance of large structures such as aircraft has been delayed by the absence of a mobile system particularly suited to the requirements of field use. This report describes the production, extensive field testing, evaluation and disposition of the first mobile neutron radiography system to satisfy the majority of requirements for field use. The system is based upon the concept of a mobile on-off neutron radiography system based on a sealed-tube ion accelerator as neutron source demonstrated earlier by the Vought Corporation. Primary features of the system are its self-propelled mobility, versatile positioning capability scaled to Army helicopter dimensions, an on-off beam capability, exposure capability measured in minutes, and suitability for AMMRC laboratory and field use. Included in the report are a description of all components of the system, an evaluation of the operation of the system, an evaluation of its radiographic capabilities, a description of installation elements for the AMMRC site, and recommendations for next-generation systems.

  7. Production, Characterization, and Acceleration of Optical Microbunches

    SciTech Connect

    Sears, Christopher M.S.

    2008-06-20

    Optical microbunches with a spacing of 800 nm have been produced for laser acceleration research. The microbunches are produced using a inverse Free-Electron-Laser (IFEL) followed by a dispersive chicane. The microbunched electron beam is characterized by coherent optical transition radiation (COTR) with good agreement to the analytic theory for bunch formation. In a second experiment the bunches are accelerated in a second stage to achieve for the first time direct net acceleration of electrons traveling in a vacuum with visible light. This dissertation presents the theory of microbunch formation and characterization of the microbunches. It also presents the design of the experimental hardware from magnetostatic and particle tracking simulations, to fabrication and measurement of the undulator and chicane magnets. Finally, the dissertation discusses three experiments aimed at demonstrating the IFEL interaction, microbunch production, and the net acceleration of the microbunched beam. At the close of the dissertation, a separate but related research effort on the tight focusing of electrons for coupling into optical scale, Photonic Bandgap, structures is presented. This includes the design and fabrication of a strong focusing permanent magnet quadrupole triplet and an outline of an initial experiment using the triplet to observe wakefields generated by an electron beam passing through an optical scale accelerator.

  8. Target designs for Accelerator Production of Tritium (APT) utilizing lithium-aluminum

    SciTech Connect

    Todosow, M.; Van Tuyle, G.J.

    1996-03-01

    A number of accelerator-driven spallation neutron-source target/blanket systems have been developed for production of tritium under the APT Program. The two systems described in this paper employ a proton linear accelerator, and a target which contains a heavy-metal(s) for the production of neutrons via spallation, and solid lithium-aluminum for the production of tritium via neutron capture. lie lithium-aluminum technology is based on that employed at Savannah River for tritium production since the 1950`s. In the APT concept tritium is produced without the presence of fissionable materials; therefore, no high-level waste is produced, and the ES&H concerns are significantly reduced compared to reactor systems.

  9. Neutron source in the MCNPX shielding calculating for electron accelerator driven facility

    SciTech Connect

    Zhong, Z.; Gohar, Y.

    2012-07-01

    Argonne National Laboratory (ANL) of USA and Kharkov Inst. of Physics and Technology (KIPT) of Ukraine have been collaborating on the design development of an experimental neutron source facility. It is an accelerator driven system (ADS) utilizing a subcritical assembly driven by electron accelerator. The facility will be utilized for performing basic and applied nuclear researches, producing medical isotopes, and training young nuclear specialists. Monte Carlo code MCNPX has been utilized as a design tool due to its capability to transport electrons, photons, and neutrons at high energies. However the facility shielding calculations with MCNPX need enormous computational resources and the small neutron yield per electron makes sampling difficulty for the Monte Carlo calculations. A method, based on generating and utilizing neutron source file, was proposed and tested. This method reduces significantly the required computer resources and improves the statistics of the calculated neutron dose outside the shield boundary. However the statistical errors introduced by generating the neutron source were not directly represented in the results, questioning the validity of this methodology, because an insufficiently sampled neutron source can cause error on the calculated neutron dose. This paper presents a procedure for the validation of the generated neutron source file. The impact of neutron source statistic on the neutron dose is examined by calculating the neutron dose as a function of the number of electron particles used for generating the neutron source files. When the value of the calculated neutron dose converges, it means the neutron source has scored sufficient records and statistic does not have apparent impact on the calculated neutron dose. In this way, the validity of neutron source and the shield analyses could be verified. (authors)

  10. Accelerator-Based Boron Neutron Capture Therapy and the Development of a Dedicated Tandem-Electrostatic-Quadrupole

    SciTech Connect

    Kreiner, A. J.; Di Paolo, H.; Burlon, A. A.; Valda, A. A.; Debray, M. E.; Somacal, H. R.; Minsky, D. M.; Kesque, J. M.; Giboudot, Y.; Levinas, P.; Fraiman, M.; Romeo, V.

    2007-10-26

    There is a generalized perception that the availability of suitable particle accelerators installed in hospitals, as neutron sources, may be crucial for the advancement of Boron Neutron Capture Therapy (BNCT). Progress on an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator for Accelerator-Based (AB)-BNCT is described here. The project goal is a machine capable of delivering 30 mA of 2.5 MeV protons to be used in conjunction with a neutron production target based on the {sup 7}Li(p,n){sup 7}Be reaction slightly beyond its resonance at 2.25 MeV. A folded tandem, with 1.25 MV terminal voltage, combined with an ESQ chain is being designed and constructed. A 30 mA proton beam of 2.5 MeV are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the {sup 7}Li(p,n){sup 7}Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. The first design and construction of an ESQ module is discussed and its electrostatic fields are investigated theoretically and experimentally. Also new beam transport calculations through the accelerator are presented.

  11. Investigation of Lead Target Nuclei Used on Accelerator-Driven Systems for Tritium Production

    NASA Astrophysics Data System (ADS)

    Tel, E.; Aydin, A.

    2012-02-01

    High-current proton accelerators are being researched at Los Alamos National Laboratory and other laboratories for accelerator production of tritium, transmuting long-lived radioactive waste into shorter-lived products, converting excess plutonium, and producing energy. These technologies make use of spallation neutrons produced in ( p,xn) and ( n,xn) nuclear reactions on high-Z targets. Through ( p,xn) and ( n,xn) nuclear reactions, neutrons are produced and are moderated by heavy water. These moderated neutrons are subsequently captured on 3He to produce tritium via the ( n,p) reaction. Tritium self-sufficiency must be maintained for a commercial fusion power plant. Rubbia succeeded in a proposal of a full scale demonstration plant of the Energy Amplifier. This plant is to be known the accelerator-driven system (ADS). The ADS can be used for production of neutrons in spallation neutron source and they can act as an intense neutron source in accelerator-driven subcritical reactors, capable of incinerating nuclear waste and of producing energy. Thorium and Uranium are nuclear fuels and Lead, Bismuth, Tungsten are the target nuclei in these reactor systems. The spallation targets can be Pb, Bi, W, etc. isotopes and these target material can be liquid or solid. Naturally Lead includes the 204Pb (%1.42), 206Pb (%24.1), 207Pb (%22.1) and 208Pb (%52.3) isotopes. The design of ADS systems and also a fusion-fission hybrid reactor systems require the knowledge of a wide range of better data. In this study, by using Hartree-Fock method with an effective nucleon-nucleon Skyrme interactions rms nuclear charge radii, rms nuclear mass radii, rms nuclear proton, neutron radii and neutron skin thickness were calculated for the 204, 206, 208Pb isotopes . The calculated results have been compared with those of the compiled experimental and theoretical values of other studies.

  12. Radiological Hazard of Spallation Products in Accelerator-Driven System

    SciTech Connect

    Saito, M.; Stankovskii, A.; Artisyuk, V.; Korovin, Yu.; Shmelev, A.; Titarenko, Yu.

    2002-09-15

    The central issue underlying this paper is related to elucidating the hazard of radioactive spallation products that might be an important factor affecting the design option of accelerator-driven systems (ADSs). Hazard analysis based on the concept of Annual Limit on Intake identifies alpha-emitting isotopes of rare earths (REs) (dysprosium, gadolinium, and samarium) as the dominant contributors to the overall toxicity of traditional (W, Pb, Pb-Bi) targets. The matter is addressed from several points of view: code validation to simulate their yields, choice of material for the neutron producing targets, and challenging the beam type. The paper quantitatively determines the domain in which the toxicity of REs exceeds that of polonium activation products broadly discussed now in connection with advertising lead-bismuth technology for the needs of ADSs.

  13. Accelerated solvent extraction for natural products isolation.

    PubMed

    Mottaleb, Mohammad A; Sarker, Satyajit D

    2012-01-01

    Accelerated solvent extraction (ASE(®)), first introduced in 1995, is an automated rapid extraction technique that utilizes common solvents at elevated temperature and pressure, and thereby increases the efficiency of extraction of organic compounds from solid and semisolid matrices. ASE(®) allows extractions for sample sizes 1-100 g in minutes, reduces solvent uses dramatically, and can be applied to a wide range of matrices, including natural products. PMID:22367894

  14. Neutron dose per fluence and weighting factors for use at high energy accelerators

    SciTech Connect

    Cossairt, J.Donald; Vaziri, Kamran; /Fermilab

    2008-07-01

    In June 2007, the United States Department of Energy incorporated revised values of neutron weighting factors into its occupational radiation protection Regulation 10 CFR Part 835 as part of updating its radiation dosimetry system. This has led to a reassessment of neutron radiation fields at high energy proton accelerators such as those at the Fermi National Accelerator Laboratory (Fermilab). Values of dose per fluence factors appropriate for accelerator radiation fields calculated elsewhere are collated and radiation weighting factors compared. The results of this revision to the dosimetric system are applied to americium-beryllium neutron energy spectra commonly used for instrument calibrations. A set of typical accelerator neutron energy spectra previously measured at Fermilab are reassessed in light of the new dosimetry system. The implications of this revision are found to be of moderate significance.

  15. Acceleration of neutrons in a scheme of a tautochronous mathematical pendulum (physical principles)

    SciTech Connect

    Rivlin, Lev A

    2010-12-09

    We consider the physical principles of neutron acceleration through a multiple synchronous interaction with a gradient rf magnetic field in a scheme of a tautochronous mathematical pendulum. (laser applications and other aspects of quantum electronics)

  16. Monitoring method for neutron flux for a spallation target in an accelerator driven sub-critical system

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang, He, Zhi-Yong; Yang, Lei; Zhang, Xue-Ying; Cui, Wen-Juan; Chen, Zhi-Qiang; Xu, Hu-Shan

    2016-07-01

    In this paper, we study a monitoring method for neutron flux for the spallation target used in an accelerator driven sub-critical (ADS) system, where a spallation target located vertically at the centre of a sub-critical core is bombarded vertically by high-energy protons from an accelerator. First, by considering the characteristics in the spatial variation of neutron flux from the spallation target, we propose a multi-point measurement technique, i.e. the spallation neutron flux should be measured at multiple vertical locations. To explain why the flux should be measured at multiple locations, we have studied neutron production from a tungsten target bombarded by a 250 MeV-proton beam with Geant4-based Monte Carlo simulations. The simulation results indicate that the neutron flux at the central location is up to three orders of magnitude higher than the flux at lower locations. Secondly, we have developed an effective technique in order to measure the spallation neutron flux with a fission chamber (FC), by establishing the relation between the fission rate measured by FC and the spallation neutron flux. Since this relation is linear for a FC, a constant calibration factor is used to derive the neutron flux from the measured fission rate. This calibration factor can be extracted from the energy spectra of spallation neutrons. Finally, we have evaluated the proposed calibration method for a FC in the environment of an ADS system. The results indicate that the proposed method functions very well. Supported by Strategic Priority Research Program of Chinese Academy of Sciences (XDA03010000 and XDA03030000) and the National Natural Science Foundation of China(91426301).

  17. Direct evidence for inelastic neutron 'acceleration' by {sup 177}Lu{sup m}

    SciTech Connect

    Roig, O.; Meot, V.; Rosse, B.; Belier, G.; Daugas, J.-M.; Morel, P.; Letourneau, A.; Menelle, A.

    2011-06-15

    The inelastic neutron acceleration cross section on the long-lived metastable state of {sup 177}Lu has been measured using a direct method. High-energy neutrons have been detected using a specially designed setup placed on a cold neutron beam extracted from the ORPHEE reactor in Saclay. The 146{+-}19 b inelastic neutron acceleration cross section in the ORPHEE cold neutron flux confirms the high cross section for this process on the {sup 177}Lu{sup m} isomer. The deviation from the 258{+-}58 b previously published obtained for a Maxwellian neutron flux at a 323 K temperature could be explained by the presence of a low energy resonance. Resonance parameters are deduced and discussed.

  18. Progress report on the accelerator production of tritium materials irradiation program

    SciTech Connect

    Maloy, S.A.; Sommer, W.F.; Brown, R.D.; Roberts, J.E.

    1997-05-01

    The Accelerator Production of Tritium (APT) project is developing an accelerator and a spoliation neutron source capable of producing tritium through neutron capture on He-3. A high atomic weight target is used to produce neutrons that are then multiplied and moderated in a blanket prior to capture. Materials used in the target and blanket region of an APT facility will be subjected to several different and mixed particle radiation environments; high energy protons (1-2 GeV), protons in the 20 MeV range, high energy neutrons, and low energy neutrons, depending on position in the target and blanket. Flux levels exceed 10{sup 14}/cm{sup 2}s in some areas. The APT project is sponsoring an irradiation damage effects program that will generate the first data-base for materials exposed to high energy particles typical of spallation neutron sources. The program includes a number of candidate materials in small specimen and model component form and uses the Los Alamos Spallation Radiation Effects Facility (LASREF) at the 800 MeV, Los Alamos Neutron Science Center (LANSCE) accelerator.

  19. Interaction of neutrons with a birefringent medium moving with an acceleration

    NASA Astrophysics Data System (ADS)

    Frank, A. I.

    2016-04-01

    Recent experiments demonstrated that the energy of a neutron traversing an accelerated sample of a refractive medium changes. Later, it was realized that such an accelerated-medium effect (AME) is quite a general phenomenon. This paper discusses some special features of the effect for a birefringent medium. In this case, AME shows quite new features. In neutron optics, where birefringence is due to the spin dependence of the refractive index, AME results in a nonstationary state with a precessing spin.

  20. Dosimetry and fast neutron energies characterization of photoneutrons produced in some medical linear accelerators

    NASA Astrophysics Data System (ADS)

    Khaled, N. E.; Attalla, E. M.; Ammar, H.; Khalil, W.

    2011-12-01

    This work focusses on the estimation of induced photoneutrons energy, fluence, and strength using nuclear track detector (NTD) (CR-39). Photoneutron energy was estimated for three different linear accelerators, LINACs as an example for the commonly used accelerators. For high-energy linear accelerators, neutrons are produced as a consequence of photonuclear reactions in the target nuclei, accelerator head, field-flattening filters and beam collimators, and other irradiated objects. NTD (CR-39) is used to evaluate energy and fluence of the fast neutron. Track length is used to estimate fast photoneutrons energy for linear accelerators (Elekta 10 MV, Elekta 15 MV, and Varian 15 MV). Results show that the estimated neutron energies for the three chosen examples of LINACs reveals neutron energies in the range of 1-2 MeV for 10 and 15 MV X-ray beams. The fluence of neutrons at the isocenter (Φtotal) is found to be (4×106 n cm2 Gy-1) for Elekta machine 10 MV. The neutron source strengths Q are calculated. It was found to be 0.2×1012 n Gy-1 X-ray at the isocenter. This work represents simple, low cost, and accurate methods of measuring fast neutrons dose and energies.

  1. Characterisation of an accelerator-based neutron source for BNCT versus beam energy

    NASA Astrophysics Data System (ADS)

    Agosteo, S.; Curzio, G.; d'Errico, F.; Nath, R.; Tinti, R.

    2002-01-01

    Neutron capture in 10B produces energetic alpha particles that have a high linear energy transfer in tissue. This results in higher cell killing and a higher relative biological effectiveness compared to photons. Using suitably designed boron compounds which preferentially localize in cancerous cells instead of healthy tissues, boron neutron capture therapy (BNCT) has the potential of providing a higher tumor cure rate within minimal toxicity to normal tissues. This clinical approach requires a thermal neutron source, generally a nuclear reactor, with a fluence rate sufficient to deliver tumorcidal doses within a reasonable treatment time (minutes). Thermal neutrons do not penetrate deeply in tissue, therefore BNCT is limited to lesions which are either superficial or otherwise accessible. In this work, we investigate the feasibility of an accelerator-based thermal neutron source for the BNCT of skin melanomas. The source was designed via MCNP Monte Carlo simulations of the thermalization of a fast neutron beam, generated by 7 MeV deuterons impinging on a thick target of beryllium. The neutron field was characterized at several deuteron energies (3.0-6.5 MeV) in an experimental structure installed at the Van De Graaff accelerator of the Laboratori Nazionali di Legnaro, in Italy. Thermal and epithermal neutron fluences were measured with activation techniques and fast neutron spectra were determined with superheated drop detectors (SDD). These neutron spectrometry and dosimetry studies indicated that the fast neutron dose is unacceptably high in the current design. Modifications to the current design to overcome this problem are presented.

  2. Charm production in neutron-nucleon interactions

    SciTech Connect

    Tzeng, L.; McBride, P.L.; Cooper, P.S.; Li, Y.; Majka, R.D.; Sandweiss, J.; Slaughter, A.J.; Taft, H.D.; Teig, L.J.; Johnson, M.E.

    1985-09-09

    Hadronic production of charmed particles in association with muons from their semileptonic decay has been observed in a high-resolution streamer-chamber experiment performed at Fermilab. A miss-distance analysis of the pictures gives a signal of 17.3 +- 4.7 events. Depending on the production model this corresponds to a range of neutron-nucleon cross sections from 8 to 50 ..mu..b, assuming an A/sup 2/3/ dependence.

  3. A measurement of actinide neutron transmutations with accelerator mass spectrometry in order to infer neutron capture cross sections

    NASA Astrophysics Data System (ADS)

    Bauder, William K.

    Improved neutron capture cross section data for transuranic and minor actinides are essential for assessing possibilities for next generation reactors and advanced fuel cycles. The Measurement of Actinide Neutron TRAnsmutation (MANTRA) project aims to make a comprehensive set of energy integrated neutron capture cross section measurements for all relevant isotopes from Th to Cf. The ability to extract these cross sections relies on the use of Accelerator Mass Spectrometry (AMS) to analyze isotopic concentrations in samples irradiated in the Advanced Test Reactor (ATR). The AMS measurements were performed at the Argonne Tandem Linear Accelerator System (ATLAS) and required a number of key technical developments to the ion source, accelerator, and detector setup. In particular, a laser ablation material injection system was developed at the electron cyclotron resonance ion source. This system provides a more effective method to produce ion beams from samples containing only 1% actinide material and offers some benefits for reducing cross talk in the source. A series of four actinide measurements are described in this dissertation. These measurements represent the most substantial AMS work attempted at ATLAS and the first results of the MANTRA project. Isotopic ratios for one and two neutron captures were measured in each sample with total uncertainties around 10%. These results can be combined with a MCNP model for the neutron fluence to infer actinide neutron capture cross sections.

  4. Neutron sources in a 24-MV medical linear accelerator.

    PubMed

    LaRiviere, P D

    1985-01-01

    During the assembly of the prototype Clinac 2500, a unique opportunity arose to measure the cumulative total neutron yield of the machine as the major subassemblies were added, section by section. Differentiation of the results led to an inventory of the relative strength of the several neutron sources identified. The method utilized the fact that the scattered neutron fluence in a cavity in concrete is nearly uniform throughout the space and proportional to the fast neutron source strength. When normalized to the neutron output of the guide with bend magnet vacuum chamber, the relative neutron source strengths found were target, 1.9; primary collimator, 2.4; steel filter, 0.6; tungsten filter, 1.5; and jaw system, 0.8 open and approximately 2.0 closed. There is reasonable agreement between these measurements and published estimates of the yields from the major components of the treatment head. PMID:4079876

  5. Production of medical radioisotopes with linear accelerators.

    PubMed

    Starovoitova, Valeriia N; Tchelidze, Lali; Wells, Douglas P

    2014-02-01

    In this study, we discuss producing radioisotopes using linear electron accelerators and address production and separation issues of photoneutron (γ,n) and photoproton (γ,p) reactions. While (γ,n) reactions typically result in greater yields, separating product nuclides from the target is challenging since the chemical properties of both are the same. Yields of (γ,p) reactions are typically lower than (γ,n) ones, however they have the advantage that target and product nuclides belong to different chemical species so their separation is often not such an intricate problem. In this paper we consider two examples, (100)Mo(γ,n)(99)Mo and (68)Zn(γ,p)(67)Cu, of photonuclear reactions. Monte-Carlo simulations of the yields are benchmarked with experimental data obtained at the Idaho Accelerator Center using a 44MeV linear electron accelerator. We propose using a kinematic recoil method for photoneutron production. This technique requires (100)Mo target material to be in the form of nanoparticles coated with a catcher material. During irradiation, (99)Mo atoms recoil and get trapped in the coating layer. After irradiation, the coating is dissolved and (99)Mo is collected. At the same time, (100)Mo nanoparticles can be reused. For the photoproduction method, (67)Cu can be separated from the target nuclides, (68)Zn, using standard exchange chromatography methods. Monte-Carlo simulations were performed and the (99)Mo activity was predicted to be about 7MBq/(g(⁎)kW(⁎)h) while (67)Cu activity was predicted to be about 1MBq/(g(⁎)kW(⁎)h). Experimental data confirm the predicted activity for both cases which proves that photonuclear reactions can be used to produce radioisotopes. Lists of medical isotopes which might be obtained using photonuclear reactions have been compiled and are included as well. PMID:24374071

  6. Neutron Production from In-situ Heavy Ice Coated Targets at Vulcan

    NASA Astrophysics Data System (ADS)

    Morrison, John; Krygier, A. G.; Kar, S.; Ahmed, H.; Alejo, A.; Clarke, R.; Fuchs, J.; Green, A.; Jung, D.; Kleinschmidt, A.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Notley, M.; Oliver, M.; Roth, M.; Vassura, L.; Zepf, M.; Borghesi, M.; Freeman, R. R.

    2015-05-01

    Laser based neutron production experiments have been performed utilizing ultra-high intensity laser accelerated ions impinging upon a secondary target. The neutron yield from such experiments may be improved if the accelerated ions were primarily deuterons taking advantage of the d-d cross section. Recent experiments have demonstrated that selective deuteron acceleration from in-situ heavy ice coating of targets can produce ion spectra where deuterons comprise > 99 % of the measured ions. Results will be presented from integrated neutron production experiments from heavy ice targets coated in-situ recently performed on the Vulcan laser at Rutherford Appleton Laboratory. We are grateful for the Staff at RAL and acknowledge funding from the US DoE. AFOSR, European Social Fund, and the Czech Republic.

  7. Neutron-proton-converter acceleration mechanism at subphotospheres of relativistic outflows.

    PubMed

    Kashiyama, Kazumi; Murase, Kohta; Mészáros, Peter

    2013-09-27

    We study a type of particle acceleration that operates via neutron-proton conversion in inelastic nuclear collisions. This mechanism can be expected for relativistic shocks at subphotospheres if relativistic outflows contain neutrons. Using a test-particle approximation, we numerically calculate the energy spectrum and the efficiency of accelerated particles, and show that a good energy fraction of the nucleons can be accelerated. This mechanism may be especially relevant if the shock is radiation mediated, and it would enhance the detectability of GeV-TeV neutrinos. PMID:24116765

  8. Propagation characteristics of neutrons leaking from the accelerator facilities.

    PubMed

    Kitaichi, Masatoshi; Sawamura, Sadashi; Wakisaka, Masashi; Kaneko, Junichi H; Ochiai, Kentaro; Nishitani, Takeo; Sawamura, Teruko

    2004-01-01

    In this study spatial and time distribution of neutrons leaking from Hokkaido University 45 MeV Electron Linac facility have measured and compared with the Monte Carlo simulations. The neutron transport processes inside and outside the facility building has been simulated using MCNP. The neutrons have measured by BF3 counters and 3He counters with polyethylene moderators up to the distance of 330 m from the facility. The spatial distribution of ambient dose equivalent converted from the counts has been compared with the simulation. The distribution estimated from the counts by the BF3 counter has been shown fairly good agreement with the calculation. The spatial distribution of counts obtained at the 45 MeV Electron Linac facility has been compared with that obtained at the Fusion Neutronics Source (FNS) facility of JAERI. The difference between the propagation characteristics of neutrons leaking from those facilities has been discussed. PMID:15353739

  9. Overview of secondary neutron production relevant to shielding inspace

    SciTech Connect

    Heilbronn, L.; Nakamura, T.; Iwata, Y.; Kurosawa, T.; Iwase, H.; Townsend, L.W.

    2004-12-03

    An overview of experimental secondary neutron measurements relevant to space-related activities is presented. Stopping target yields and cross section measurements conducted at particle accelerators using heavy ions with energies >100 MeV per nucleon are discussed.

  10. Neutron field measurements for alara purposes around a Van de Graaff accelerator building.

    PubMed

    Kockerols, P; Lebacq, A L; Gasparro, J; Hult, M; Janssens, H; Lövestam, G; Vanhavere, F

    2004-01-01

    The Institute for Reference Materials and Measurements operates a 7.0 MV Van de Graaff accelerator to generate monoenergetic neutron radiation for experimental applications. Owing to increased intensities of generated neutron fields and the more stringent regulation related to the maximum dose for the public, a concrete shielding wall surrounding the experimental building was constructed. This paper presents a study aiming at evaluating the effect of the shielding on the neutron field outside the wall. For this purpose, the following measurements were carried out around the building: (1) cartography of the neutron field for different experimental conditions; (2) measurement of neutron spectra using multiple Bonner spheres; (3) activation measurements using gold discs followed by low-level gamma spectrometry. From the measurements, it can be concluded that the wall fulfils its purpose to reduce the neutron dose rate to the surrounding area to an acceptable level. PMID:15353736

  11. Study of an External Neutron Source for an Accelerator-Driven System using the PHITS Code

    SciTech Connect

    Sugawara, Takanori; Iwasaki, Tomohiko; Chiba, Takashi

    2005-05-24

    A code system for the Accelerator Driven System (ADS) has been under development for analyzing dynamic behaviors of a subcritical core coupled with an accelerator. This code system named DSE (Dynamics calculation code system for a Subcritical system with an External neutron source) consists of an accelerator part and a reactor part. The accelerator part employs a database, which is calculated by using PHITS, for investigating the effect related to the accelerator such as the changes of beam energy, beam diameter, void generation, and target level. This analysis method using the database may introduce some errors into dynamics calculations since the neutron source data derived from the database has some errors in fitting or interpolating procedures. In this study, the effects of various events are investigated to confirm that the method based on the database is appropriate.

  12. High-energy in-beam neutron measurements of metal-based shielding for accelerator-driven spallation neutron sources

    NASA Astrophysics Data System (ADS)

    DiJulio, D. D.; Cooper-Jensen, C. P.; Björgvinsdóttir, H.; Kokai, Z.; Bentley, P. M.

    2016-05-01

    Metal-based shielding plays an important role in the attenuation of harmful and unwanted radiation at an accelerator-driven spallation neutron source. At the European Spallation Source, currently under construction in Lund, Sweden, metal-based materials are planned to be used extensively as neutron guide substrates in addition to other shielding structures around neutron guides. The usage of metal-based materials in the vicinity of neutron guides however requires careful consideration in order to minimize potential background effects in a neutron instrument at the facility. Therefore, we have carried out a combined study involving high-energy neutron measurements and Monte Carlo simulations of metal-based shielding, both to validate the simulation methodology and also to investigate the benefits and drawbacks of different metal-based solutions. The measurements were carried out at The Svedberg Laboratory in Uppsala, Sweden, using a 174.1 MeV neutron beam and various thicknesses of aluminum-, iron-, and copper-based shielding blocks. The results were compared to geant4 simulations and revealed excellent agreement. Our combined study highlights the particular situations where one type of metal-based solution may be preferred over another.

  13. From laser particle acceleration to the synthesis of extremely neutron rich isotopes via the novel fission-fusion mechanism

    NASA Astrophysics Data System (ADS)

    Thirolf, P. G.

    2015-02-01

    High-power, short pulse lasers have emerged in the last decade as attractive tools for accelerating charged particles (electrons, ions) to high energies over mm-scale acceleration lengths, thus promising to rival conventional acceleration techniques in the years ahead. In the first part of the article, the principles of laser-plasma interaction as well as the techniques and the current status of the acceleration of electron and ion beams will be briefly introduced. In particular with the upcoming next generation of multi-PW class laser systems, such as the one under construction for the ELI-Nuclear Physics project in Bucharest (ELI-NP), very efficient acceleration mechanisms for brilliant ion beams like radiation pressure acceleration (RPA) come into reach. Here, ultra-dense ion beams reaching solid-state density can be accelerated from thin target foils, exceeding the density of conventionally accelerated ion beams by about 14 orders of magnitude. This unique property of laser-accelerated ion beams can be exploited to explore the scenario of a new reaction mechanism called `fission-fusion', which will be introduced in the second part of the article. Accelerating fissile species (e.g. 232Th ) towards a second layer of the same material will lead to fission both of the beam-like and target-like particles. Due to the close to solid-state density of the accelerated ion bunches, fusion may occur between neutron-rich (light) fission products. This may open an access path towards extremely neutron-rich nuclides in the vicinity of the N=126 waiting point of the astrophysical r process. `Waiting points' at closed nucleon shells play a crucial role in controlling the reaction rates. However, since most of the pathway of heavy-element formation via the rapid-neutron capture process (r-process) runs in `terra incognita' of the nuclear landscape, in particular the waiting point at N=126 is yet unexplored and will remain largely inaccessible to conventional nuclear reaction

  14. From laser particle acceleration to the synthesis of extremely neutron rich isotopes via the novel fission-fusion mechanism

    SciTech Connect

    Thirolf, P. G.

    2015-02-24

    High-power, short pulse lasers have emerged in the last decade as attractive tools for accelerating charged particles (electrons, ions) to high energies over mm-scale acceleration lengths, thus promising to rival conventional acceleration techniques in the years ahead. In the first part of the article, the principles of laser-plasma interaction as well as the techniques and the current status of the acceleration of electron and ion beams will be briefly introduced. In particular with the upcoming next generation of multi-PW class laser systems, such as the one under construction for the ELI-Nuclear Physics project in Bucharest (ELI-NP), very efficient acceleration mechanisms for brilliant ion beams like radiation pressure acceleration (RPA) come into reach. Here, ultra-dense ion beams reaching solid-state density can be accelerated from thin target foils, exceeding the density of conventionally accelerated ion beams by about 14 orders of magnitude. This unique property of laser-accelerated ion beams can be exploited to explore the scenario of a new reaction mechanism called ‘fission-fusion’, which will be introduced in the second part of the article. Accelerating fissile species (e.g. {sup 232}Th) towards a second layer of the same material will lead to fission both of the beam-like and target-like particles. Due to the close to solid-state density of the accelerated ion bunches, fusion may occur between neutron-rich (light) fission products. This may open an access path towards extremely neutron-rich nuclides in the vicinity of the N=126 waiting point of the astrophysical r process. ‘Waiting points’ at closed nucleon shells play a crucial role in controlling the reaction rates. However, since most of the pathway of heavy-element formation via the rapid-neutron capture process (r-process) runs in ‘terra incognita’ of the nuclear landscape, in particular the waiting point at N=126 is yet unexplored and will remain largely inaccessible to conventional

  15. MCNP Neutron Simulations: The Effectiveness of the University of Kentucky Accelerator Laboratory Pit

    NASA Astrophysics Data System (ADS)

    Jackson, Daniel; Nguyen, Thien An; Hicks, S. F.; Rice, Ben; Vanhoy, J. R.

    2015-10-01

    The design of the Van de Graaff Particle Accelerator complex at the University of Kentucky is marked by the unique addition of a pit in the main neutron scattering room underneath the neutron source and detection shielding assembly. This pit was constructed as a neutron trap in order to decrease the amount of neutron flux within the laboratory. Such a decrease of background neutron flux effectively reduces as much noise as possible in detection of neutrons scattering off of desired samples to be studied. This project uses the Monte-Carlo N-Particle Transport Code (MCNP) to model the structure of the accelerator complex, gas cell, and the detector's collimator and shielding apparatus to calculate the neutron flux in various sections of the laboratory. Simulations were completed with baseline runs of 107 neutrons of energies 4 MeV and 17 MeV, produced respectively by 3H(p,n)3He and 3H(d,n)4He source reactions. In addition, a comparison model of the complex with simply a floor and no pit was designed, and the respective neutron fluxes of both models were calculated and compared. The results of the simulations seem to affirm the validity of the pit design in significantly reducing the overall neutron flux throughout the accelerator complex, which could be used in future designs to increase the precision and reliability of data. This project was supported in part by the DOE NEUP Grant NU-12-KY-UK-0201-05 and the Donald A. Cowan Physics Institute at the University of Dallas.

  16. Measurements Of Spin Observables In Pseudoscalar-Meson Photo-Production Using Polarized Neutrons In Solid HD

    SciTech Connect

    Kageya, Tsuneo

    2014-01-01

    Psuedo-scalar meson photo production measurements have been carried out with longitudinally-polarized neutrons using the circularly and linearly polarized photon beams and the CLAS at Thomas Jefferson National Accelerator Facility (Jlab). The experiment aims to obtain a complete set of spin observables on an efficient neutron target. Preliminary E asymmetries for the exclusive reaction, gamma + n(p)--> pi- + p(p), selecting quasi free neutron kinematics are discussed.

  17. Characterization of an accelerator neutron source based on the Be(d,n) reaction

    SciTech Connect

    Meadows, J.W.; Smith, D.L.

    1992-07-01

    Small accelerator neutron sources offer considerable potential for applied neutron radiography applications. Among the desirable features are relatively low costs, limited operating hazards, opportunities for tailoring primary neutron spectra, compactness and portability, and modest licensing requirements (compared to fission reactors). However, exploitation of this potential has been somewhat limited, in part, by incomplete knowledge of the primary-neutron yields and energy spectra from the favorable source reactions. This work describes an extensive experimental determination of zero-degree neutron yields and energy spectra from the {sup 9}Be(d,n) {sup 10}B source reaction, for incident deuterons of 2.6 to 7.0 MeV on a thick beryllium metal target. This information was acquired by means of time-of-flight measurements that were conducted with a calibrated uranium fission detector. Tables and plots of neutron-producing reaction data are presented. This information provides input which will be essential for applications involving the primary spectrum as well as for the design of neutron moderators and for calculation of thermal-neutron yield factors. Such analyses will be prerequisites in assessing the suitability of this source for various possible neutron radiography applications and, also, for assisting in the design of appropriate detectors to be used in neutron imaging devices.

  18. Characterization of an accelerator neutron source based on the Be(d,n) reaction

    SciTech Connect

    Meadows, J.W.; Smith, D.L.

    1992-01-01

    Small accelerator neutron sources offer considerable potential for applied neutron radiography applications. Among the desirable features are relatively low costs, limited operating hazards, opportunities for tailoring primary neutron spectra, compactness and portability, and modest licensing requirements (compared to fission reactors). However, exploitation of this potential has been somewhat limited, in part, by incomplete knowledge of the primary-neutron yields and energy spectra from the favorable source reactions. This work describes an extensive experimental determination of zero-degree neutron yields and energy spectra from the {sup 9}Be(d,n) {sup 10}B source reaction, for incident deuterons of 2.6 to 7.0 MeV on a thick beryllium metal target. This information was acquired by means of time-of-flight measurements that were conducted with a calibrated uranium fission detector. Tables and plots of neutron-producing reaction data are presented. This information provides input which will be essential for applications involving the primary spectrum as well as for the design of neutron moderators and for calculation of thermal-neutron yield factors. Such analyses will be prerequisites in assessing the suitability of this source for various possible neutron radiography applications and, also, for assisting in the design of appropriate detectors to be used in neutron imaging devices.

  19. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  20. Development of beryllium-based neutron target system with three-layer structure for accelerator-based neutron source for boron neutron capture therapy.

    PubMed

    Kumada, Hiroaki; Kurihara, Toshikazu; Yoshioka, Masakazu; Kobayashi, Hitoshi; Matsumoto, Hiroshi; Sugano, Tomei; Sakurai, Hideyuki; Sakae, Takeji; Matsumura, Akira

    2015-12-01

    The iBNCT project team with University of Tsukuba is developing an accelerator-based neutron source. Regarding neutron target material, our project has applied beryllium. To deal with large heat load and blistering of the target system, we developed a three-layer structure for the target system that includes a blistering mitigation material between the beryllium used as the neutron generator and the copper heat sink. The three materials were bonded through diffusion bonding using a hot isostatic pressing method. Based on several verifications, our project chose palladium as the intermediate layer. A prototype of the neutron target system was produced. We will verify that sufficient neutrons for BNCT treatment are generated by the device in the near future. PMID:26260448

  1. Applying nonlinear diffusion acceleration to the neutron transport k-Eigenvalue problem with anisotropic scattering

    SciTech Connect

    Willert, Jeffrey; Park, H.; Taitano, William

    2015-10-12

    High-order/low-order (or moment-based acceleration) algorithms have been used to significantly accelerate the solution to the neutron transport k-eigenvalue problem over the past several years. Recently, the nonlinear diffusion acceleration algorithm has been extended to solve fixed-source problems with anisotropic scattering sources. In this paper, we demonstrate that we can extend this algorithm to k-eigenvalue problems in which the scattering source is anisotropic and a significant acceleration can be achieved. Lastly, we demonstrate that the low-order, diffusion-like eigenvalue problem can be solved efficiently using a technique known as nonlinear elimination.

  2. ESS-Bilbao light-ion linear accelerator and neutron source: design and applications

    NASA Astrophysics Data System (ADS)

    Abad, E.; Arredondo, I.; Badillo, I.; Belver, D.; Bermejo, F. J.; Bustinduy, I.; Cano, D.; Cortazar, D.; de Cos, D.; Djekic, S.; Domingo, S.; Echevarria, P.; Eguiraun, M.; Etxebarria, V.; Fernandez, D.; Fernandez, F. J.; Feuchtwanger, J.; Garmendia, N.; Harper, G.; Hassanzadegan, H.; Jugo, J.; Legarda, F.; Magan, M.; Martinez, R.; Megia, A.; Muguira, L.; Mujika, G.; Muñoz, J. L.; Ortega, A.; Ortega, J.; Perlado, M.; Portilla, J.; Rueda, I.; Sordo, F.; Toyos, V.; Vizcaino, A.

    2011-10-01

    The baseline design for the ESS-Bilbao light-ion linear accelerator and neutron source has been completed and the normal conducting section of the linac is at present under construction. The machine has been designed to be compliant with ESS specifications following the international guidelines of such project as described in Ref. [1]. The new accelerator facility in Bilbao will serve as a base for support of activities on accelerator physics carried out in Spain and southern Europe in the frame of different ongoing international collaborations. Also, a number of applications have been envisaged in the new Bilbao facility for the outgoing light ion beams as well as from fast neutrons produced by low-energy neutron-capture targets, which are briefly described.

  3. Shielding design of a treatment room for an accelerator-based neutron source for BNCT

    SciTech Connect

    Evans, J.F.; Blue, T.E.

    1995-12-31

    For several years, research has been ongoing in the Ohio State University (OSU) Nuclear Engineering Program toward the development of an accelerator-based irradiation facility (ANIF) neutron source for boron neutron capture therapy (BNCT). The ANIF, which is planned to be built in a hospital, has been conceptually designed and analyzed. After Qu, an OSU researcher, determined that the shielding design of a 6-MV X-ray treatment room was inadequate to protect personnel from an accelerator neutron source operating at 30 mA, we decided to analyze and determine the shielding requirements of a treatment room for an ANIF. We determined the amount of shielding that would be sufficient to protect facility personnel from excessive radiation exposure caused by operation of the accelerator at 30 mA.

  4. High neutronic efficiency, low current targets for accelerator-based BNCT applications

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Todosow, M.

    1998-08-01

    The neutronic efficiency of target/filters for accelerator-based BNCT applications is measured by the proton current required to achieve a desirable neutron current at the treatment port (10{sup 9} n/cm{sup 2}/s). In this paper the authors describe two possible targeyt/filter concepts wihch minimize the required current. Both concepts are based on the Li-7 (p,n)Be-7 reaction. Targets that operate near the threshold energy generate neutrons that are close tothe desired energy for BNCT treatment. Thus, the filter can be extremely thin ({approximately} 5 cm iron). However, this approach has an extremely low neutron yield (n/p {approximately} 1.0({minus}6)), thus requiring a high proton current. The proposed solutino is to design a target consisting of multiple extremely thin targets (proton energy loss per target {approximately} 10 keV), and re-accelerate the protons between each target. Targets operating at ihgher proton energies ({approximately} 2.5 MeV) have a much higher yield (n/p {approximately} 1.0({minus}4)). However, at these energies the maximum neutron energy is approximately 800 keV, and thus a neutron filter is required to degrade the average neutron energy to the range of interest for BNCT (10--20 keV). A neutron filter consisting of fluorine compounds and iron has been investigated for this case. Typically a proton current of approximately 5 mA is required to generate the desired neutron current at the treatment port. The efficiency of these filter designs can be further increased by incorporating neutron reflectors that are co-axial with the neutron source. These reflectors are made of materials which have high scattering cross sections in the range 0.1--1.0 MeV.

  5. Accelerator mass spectrometry of 36Cl produced by neutrons from the Hiroshima bomb.

    PubMed

    Kato, K; Habara, M; Yoshizawa, Y; Biebel, U; Haberstock, G; Heinzl, J; Korschinek, G; Morinaga, H; Nolte, E

    1990-10-01

    Accelerator mass spectrometry was performed at the Munich tandem laboratory to determine 36Cl/Cl ratios of samples from a tombstone exposed to neutrons from the Hiroshima bomb. The ratios were determined from the surface to deeper positions. The depth profile of 36Cl/Cl can be used for estimating the neutron energy distribution and intensity near the hypocentre in Hiroshima. PMID:1976726

  6. Study of reactions with neutron production in pp and pd collisions at 1 GeV

    SciTech Connect

    Baturin, V.N.; Koptev, V.P.; Maev, E.M.; Makarov, M.M.; Nelyubin, V.V.; Sulimov, V.V.; Khanzadeev, A.V.; Shcherbakov, G.V.

    1980-02-01

    Absolute doubly differential cross sections for production of neutrons of energy 350--1000 MeV on bombardment of hydrogen and deuterium with 1-GeV protons have been measured at angles 4, 7.5, 11.3, and 13.2/sup 0/. The neutron energy was determined by the time-of-flight method with utilization of the time microstructure of the accelerator beam. Cross sections for neutron production in reactions with meson production were obtained. It is noted that the dominant process in these reactions is the formation of the triangle-open(1232) isobar in the intermediate state. Cross sections for quasielastic knockout of neutrons from deuterium were determined. The contribution of spin-dependent amplitudes to the pn..-->..np charge-exchange cross section was estimated an an angle 0/sup 0/.

  7. Tandem-ESQ for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT)

    SciTech Connect

    Kreiner, A. J.; Kwan, J. W.; Henestroza, E.; Burlon, A. A.; Di Paolo, H.; Minsky, D.; Debray, M.; Valda, A.; Somacal, H. R.

    2007-02-12

    A folded tandem, with 1.25 MV terminal voltage, combined with an ElectroStatic Quadrupole (ESQ) chain is being proposed as a machine for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT). The machine is shown to be capable of accelerating a 30 mA proton beam to 2.5 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the on the 7Li(p,n)7Be reaction, to perform BNCT treatment for deep seated tumors in less than an hour.

  8. Analysis of accelerator based neutron spectra for BNCT using proton recoil spectroscopy

    SciTech Connect

    Wielopolski, L.; Ludewig, H.; Powell, J.R.; Raparia, D.; Alessi, J.G.; Lowenstein, D.I.

    1999-03-01

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase 1/2 clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra, alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark

  9. ANALYSIS OF ACCELERATOR BASED NEUTRON SPECTRA FOR BNCT USING PROTON RECOIL SPECTROSCOPY

    SciTech Connect

    WIELOPOLSKI,L.; LUDEWIG,H.; POWELL,J.R.; RAPARIA,D.; ALESSI,J.G.; LOWENSTEIN,D.I.

    1998-11-06

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase I/II clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark

  10. Polymer gel dosimetry for neutron beam in the Neutron Exposure Accelerator System for Biological Effect Experiments (NASBEE)

    NASA Astrophysics Data System (ADS)

    Kawamura, H.; Sato, H.; Hamano, T.; Suda, M.; Yoshii, H.

    2015-01-01

    This study aimed to investigate whether gel dosimetry could be used to measure neutron beams. We irradiated a BANG3-type polymer gel dosimeter using neutron beams in the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) at the National Institute of Radiological Sciences (NIRS) in Japan. First, the polymer gels were irradiated from 0 to 7.0 Gy to investigate the dose-R2 responses. Irradiated gels were evaluated using 1.5-T magnetic resonance R2 images. Second, the polymer gels were irradiated to 1.0, 3.0, and 5.0 Gy to acquire a depth-R2 response curve. The dose-R2 response curve was linear up to approximately 7 Gy, with a slope of 1.25 Gy-1·s-1. Additionally, compared with the photon- irradiated gels, the neutron-irradiated gels had lower R2 values. The acquired depth-R2 curves of the central axis from the 3.0- and 5.0-Gy neutron dose-irradiated gels exhibited an initial build-up. Although, a detailed investigation is needed, polymer gel dosimetry is effective for measuring the dose-related R2 linearity and depth-R2 relationships of neutron beams.

  11. Simulation study of accelerator based quasi-mono-energetic epithermal neutron beams for BNCT.

    PubMed

    Adib, M; Habib, N; Bashter, I I; El-Mesiry, M S; Mansy, M S

    2016-01-01

    Filtered neutron techniques were applied to produce quasi-mono-energetic neutron beams in the energy range of 1.5-7.5 keV at the accelerator port using the generated neutron spectrum from a Li (p, n) Be reaction. A simulation study was performed to characterize the filter components and transmitted beam lines. The feature of the filtered beams is detailed in terms of optimal thickness of the primary and additive components. A computer code named "QMNB-AS" was developed to carry out the required calculations. The filtered neutron beams had high purity and intensity with low contamination from the accompanying thermal, fast neutrons and γ-rays. PMID:26474209

  12. Fusion-neutron-yield, activation measurements at the Z accelerator: design, analysis, and sensitivity.

    PubMed

    Hahn, K D; Cooper, G W; Ruiz, C L; Fehl, D L; Chandler, G A; Knapp, P F; Leeper, R J; Nelson, A J; Smelser, R M; Torres, J A

    2014-04-01

    We present a general methodology to determine the diagnostic sensitivity that is directly applicable to neutron-activation diagnostics fielded on a wide variety of neutron-producing experiments, which include inertial-confinement fusion (ICF), dense plasma focus, and ion beam-driven concepts. This approach includes a combination of several effects: (1) non-isotropic neutron emission; (2) the 1/r(2) decrease in neutron fluence in the activation material; (3) the spatially distributed neutron scattering, attenuation, and energy losses due to the fielding environment and activation material itself; and (4) temporally varying neutron emission. As an example, we describe the copper-activation diagnostic used to measure secondary deuterium-tritium fusion-neutron yields on ICF experiments conducted on the pulsed-power Z Accelerator at Sandia National Laboratories. Using this methodology along with results from absolute calibrations and Monte Carlo simulations, we find that for the diagnostic configuration on Z, the diagnostic sensitivity is 0.037% ± 17% counts/neutron per cm(2) and is ∼ 40% less sensitive than it would be in an ideal geometry due to neutron attenuation, scattering, and energy-loss effects. PMID:24784607

  13. Fusion-neutron-yield, activation measurements at the Z accelerator: Design, analysis, and sensitivity

    SciTech Connect

    Hahn, K. D. Ruiz, C. L.; Fehl, D. L.; Chandler, G. A.; Knapp, P. F.; Smelser, R. M.; Torres, J. A.; Cooper, G. W.; Nelson, A. J.; Leeper, R. J.

    2014-04-15

    We present a general methodology to determine the diagnostic sensitivity that is directly applicable to neutron-activation diagnostics fielded on a wide variety of neutron-producing experiments, which include inertial-confinement fusion (ICF), dense plasma focus, and ion beam-driven concepts. This approach includes a combination of several effects: (1) non-isotropic neutron emission; (2) the 1/r{sup 2} decrease in neutron fluence in the activation material; (3) the spatially distributed neutron scattering, attenuation, and energy losses due to the fielding environment and activation material itself; and (4) temporally varying neutron emission. As an example, we describe the copper-activation diagnostic used to measure secondary deuterium-tritium fusion-neutron yields on ICF experiments conducted on the pulsed-power Z Accelerator at Sandia National Laboratories. Using this methodology along with results from absolute calibrations and Monte Carlo simulations, we find that for the diagnostic configuration on Z, the diagnostic sensitivity is 0.037% ± 17% counts/neutron per cm{sup 2} and is ∼ 40% less sensitive than it would be in an ideal geometry due to neutron attenuation, scattering, and energy-loss effects.

  14. Fusion-neutron-yield, activation measurements at the Z accelerator: Design, analysis, and sensitivity

    NASA Astrophysics Data System (ADS)

    Hahn, K. D.; Cooper, G. W.; Ruiz, C. L.; Fehl, D. L.; Chandler, G. A.; Knapp, P. F.; Leeper, R. J.; Nelson, A. J.; Smelser, R. M.; Torres, J. A.

    2014-04-01

    We present a general methodology to determine the diagnostic sensitivity that is directly applicable to neutron-activation diagnostics fielded on a wide variety of neutron-producing experiments, which include inertial-confinement fusion (ICF), dense plasma focus, and ion beam-driven concepts. This approach includes a combination of several effects: (1) non-isotropic neutron emission; (2) the 1/r2 decrease in neutron fluence in the activation material; (3) the spatially distributed neutron scattering, attenuation, and energy losses due to the fielding environment and activation material itself; and (4) temporally varying neutron emission. As an example, we describe the copper-activation diagnostic used to measure secondary deuterium-tritium fusion-neutron yields on ICF experiments conducted on the pulsed-power Z Accelerator at Sandia National Laboratories. Using this methodology along with results from absolute calibrations and Monte Carlo simulations, we find that for the diagnostic configuration on Z, the diagnostic sensitivity is 0.037% ± 17% counts/neutron per cm2 and is ˜ 40% less sensitive than it would be in an ideal geometry due to neutron attenuation, scattering, and energy-loss effects.

  15. Neutron production from polyethylene and common spacecraft materials.

    PubMed

    Maurer, R H; Roth, D R; Kinnison, J D; Jordan, T M; Heilbronn, L H; Miller, J; Zeitlin, C J

    2001-12-01

    We report experimental measurements of neutron production from collisions of neutron beams with polyethylene blocks simulating tissue at the Los Alamos National Laboratory Neutron Science Center and 1 GeV/amu iron nuclei with spacecraft shielding materials at the Brookhaven National Laboratory AGS. PMID:12033226

  16. Medical Isotope Production Analyses In KIPT Neutron Source Facility

    SciTech Connect

    Talamo, Alberto; Gohar, Yousry

    2016-01-01

    Medical isotope production analyses in Kharkov Institute of Physics and Technology (KIPT) neutron source facility were performed to include the details of the irradiation cassette and the self-shielding effect. An updated detailed model of the facility was used for the analyses. The facility consists of an accelerator-driven system (ADS), which has a subcritical assembly using low-enriched uranium fuel elements with a beryllium-graphite reflector. The beryllium assemblies of the reflector have the same outer geometry as the fuel elements, which permits loading the subcritical assembly with different number of fuel elements without impacting the reflector performance. The subcritical assembly is driven by an external neutron source generated from the interaction of 100-kW electron beam with a tungsten target. The facility construction was completed at the end of 2015, and it is planned to start the operation during the year of 2016. It is the first ADS in the world, which has a coolant system for removing the generated fission power. Argonne National Laboratory has developed the design concept and performed extensive design analyses for the facility including its utilization for the production of different radioactive medical isotopes. 99Mo is the parent isotope of 99mTc, which is the most commonly used medical radioactive isotope. Detailed analyses were performed to define the optimal sample irradiation location and the generated activity, for several radioactive medical isotopes, as a function of the irradiation time.

  17. Accelerator Production of 225Ac For Alpha-Immunotherapy

    NASA Astrophysics Data System (ADS)

    Weidner, J. W.; Nortier, F. M.; Bach, H. T.; John, K. D.; Couture, A.; Ullmann, J. L.; Fassbender, M. E.; Goff, G. S.; Taylor, W.; Valdez, F.; Wolfsberg, L. E.; Cisneros, M.; Dry, D.; Gallegos, M.; Gritzo, R.; Bitteker, L. J.; Wender, S.; Baty, R. S.

    2011-06-01

    225Ac has tremendous potential for the treatment of metastatic cancer due to the four alpha-particles emitted during its decay to stable 209Bi. Additionally, it is one of the few alpha-emitters being considered for clinical trials. The anticipated 225Ac demand for these trials is expected to far exceed the annual worldwide supply of approximately 1,000 mCi/yr. Consequently, the DOE Office of Science has funded investigations into accelerator-based production of 225Ac. Existing 232Th(p,x)225Ac cross section data indicate that up to 480 mCi/day of 225Ac could be created by bombarding a thick target of natural thorium with 100 MeV protons at the Los Alamos Isotope Production Facility. To verify these predictions, experiments are underway at the Los Alamos Neutron Science Center to measure the 232Th(p,x)225Ac production cross sections for protons in the energy range 40-200 MeV, and at 800 MeV. For 800 MeV protons, preliminary results indicate that the 225Ac production cross section is 12.4±0.6 mb and the 225Ra production cross section is 3.2±0.2 mb. Moreover, preliminary results suggest that the 227Ac production cross section is 16±1 mb. Experiments to measure these same cross sections at proton energies below 200 MeV are planned for the last half of calendar year 2010.

  18. Accelerator Production of {sup 225}Ac For Alpha-Immunotherapy

    SciTech Connect

    Weidner, J. W.; Nortier, F. M.; Bach, H. T.; John, K. D.; Couture, A.; Ullmann, J. L.; Fassbender, M. E.; Goff, G. S.; Taylor, W.; Valdez, F.; Wolfsberg, L. E.; Cisneros, M.; Dry, D.; Gallegos, M.; Gritzo, R.; Bitteker, L. J.; Wender, S.; Baty, R. S.

    2011-06-01

    {sup 225}Ac has tremendous potential for the treatment of metastatic cancer due to the four alpha-particles emitted during its decay to stable {sup 209}Bi. Additionally, it is one of the few alpha-emitters being considered for clinical trials. The anticipated {sup 225}Ac demand for these trials is expected to far exceed the annual worldwide supply of approximately 1,000 mCi/yr. Consequently, the DOE Office of Science has funded investigations into accelerator-based production of {sup 225}Ac. Existing {sup 232}Th(p,x){sup 225}Ac cross section data indicate that up to 480 mCi/day of {sup 225}Ac could be created by bombarding a thick target of natural thorium with 100 MeV protons at the Los Alamos Isotope Production Facility. To verify these predictions, experiments are underway at the Los Alamos Neutron Science Center to measure the {sup 232}Th(p,x){sup 225}Ac production cross sections for protons in the energy range 40-200 MeV, and at 800 MeV. For 800 MeV protons, preliminary results indicate that the {sup 225}Ac production cross section is 12.4{+-}0.6 mb and the {sup 225}Ra production cross section is 3.2{+-}0.2 mb. Moreover, preliminary results suggest that the {sup 227}Ac production cross section is 16{+-}1 mb. Experiments to measure these same cross sections at proton energies below 200 MeV are planned for the last half of calendar year 2010.

  19. Nonlinear Acceleration Methods for Even-Parity Neutron Transport

    SciTech Connect

    W. J. Martin; C. R. E. De Oliveira; H. Park

    2010-05-01

    Convergence acceleration methods for even-parity transport were developed that have the potential to speed up transport calculations and provide a natural avenue for an implicitly coupled multiphysics code. An investigation was performed into the acceleration properties of the introduction of a nonlinear quasi-diffusion-like tensor in linear and nonlinear solution schemes. Using the tensor reduced matrix as a preconditioner for the conjugate gradients method proves highly efficient and effective. The results for the linear and nonlinear case serve as the basis for further research into the application in a full three-dimensional spherical-harmonics even-parity transport code. Once moved into the nonlinear solution scheme, the implicit coupling of the convergence accelerated transport method into codes for other physics can be done seamlessly, providing an efficient, fully implicitly coupled multiphysics code with high order transport.

  20. CMFD acceleration of spatial domain-decomposed neutron transport problems

    SciTech Connect

    Kelley, B. W.; Larsen, E. W.

    2012-07-01

    A significant limitation to parallelizing the solution of neutron transport problems is the need for sweeps across the entirety of the problem domain. Angular domain decomposition is common practice, as the equations for each direction are independent aside from their shared scattering/fission source. Accordingly, spatial domain decomposition does not naturally arise in the transport equations and is therefore less frequent in practice. In this paper, we show that a neutron transport domain can be straightforwardly divided into independent, parallelizable sweep regions, globally linked with the standard CMFD method, with an additional update equation. We verify, theoretically (via Fourier analysis) and computationally, that the convergence properties of this method are stable and nominally as rapid as standard CMFD. (authors)

  1. Bremsstrahlung pair-production of positrons with low neutron background.

    SciTech Connect

    Lessner, E.

    1998-09-16

    Minimization of component activation is highly desirable at accelerator-based positron sources. Electrons in the 8- to 14-MeV energy range impinging on a target produce photons energetic enough to create electron-positron pairs; however, few of the photons are energetic enough to produce photoneutrons. Slow positron production by low-energy electrons impinging on a multilayer tungsten target with and without electromagnetic extraction between the layers was studied by simulation. The neutron background from 14-MeV electrons is expected to be significantly lower than that encountered with higher-energy electron beams. Numerical results are presented and some ideas for a low-activation slow-positron source are discussed.

  2. Beamed neutron emission driven by laser accelerated light ions

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    Highly anisotropic, beam-like neutron emission with peak flux of the order of 109 n/sr was obtained from light nuclei reactions in a pitcher–catcher scenario, by employing MeV ions driven by a sub-petawatt laser. The spatial profile of the neutron beam, fully captured for the first time by employing a CR39 nuclear track detector, shows a FWHM divergence angle of ∼ 70^\\circ , with a peak flux nearly an order of magnitude higher than the isotropic component elsewhere. The observed beamed flux of neutrons is highly favourable for a wide range of applications, and indeed for further transport and moderation to thermal energies. A systematic study employing various combinations of pitcher–catcher materials indicates the dominant reactions being d(p, n+p)1H and d(d,n)3He. Albeit insufficient cross-section data are available for modelling, the observed anisotropy in the neutrons’ spatial and spectral profiles is most likely related to the directionality and high energy of the projectile ions.

  3. Feasibility study of accelerator based production of molybdenum-99/technetium-99m

    NASA Astrophysics Data System (ADS)

    Tchelidze, Lali

    Stability of supply in the medical radioisotope market is now of overriding importance. One of the most commonly used radioisotopes is 99mTc, which is produced from 99Mo decay. 99Mo has been produced in nuclear reactors before, however these reactors are aging and have been not reliable lately and there is a great need to find an alternative for the production. In the current project, photo-neutron production of 99Mo/ 99mTc was investigated. An electron linear accelerator at the Idaho Accelerator Center was used to study the feasibility of 99mTc production using bremsstrahlung photon beams from the accelerator. The kinematic recoil process that occurs with every photo nuclear reaction was exploited. With the emission of a neutron in a photo nuclear reaction, the parent nucleus recoils in order to conserve momentum. This recoil can be used to separate 99Mo from 100Mo, at which point one has a very pure and very high specific activity source of 99Mo. We verified the photo-neutron production rates for 99Mo. Also, the kinematic recoil process was modeled and separation efficiencies were measured experimentally. We concluded that it is feasible to produce high 99Mo activities, however nano-particles of molybdenum have to be used and a clean nano-particle separation method has to be achieved.

  4. The modeling of a linear multi-beam deuteron compact accelerator for neutron generation

    NASA Astrophysics Data System (ADS)

    Araujo, Wagner L.; Campos, Tarcisio P. R.

    2012-07-01

    There is a prominent interest in obtaining high-flux neutron generators due to its wide range of applications and possibilities. The beam current that reaches the target is one of the main factors for determining the performance of the generator. In the present paper we address the modeling of a deuteron compact accelerator for neutron generation underlying the electrode placement and providing an optimized multiple beam accelerator geometry. The methodology consists of electrode displacement calculations and simulations of the deuteron and neutron beam transport. A phenomenological model has been proposed based on experimental data, which provides two electrode configuration patterns. Both configurations were compared through electromagnetic simulations considering a single-beam accelerator-type. The configuration with highest ion current has led to a new geometry incorporating multiple beams. The final prototype presents an interesting beam profile achieving deuteron kinetic energy in the order of 180 keV and current up to 198 mA. Estimated yield for this generator was 1012 n/s. A shield was designed, based on Monte Carlo simulations. Dose calculation was appraised showing a neutron and photon dose rate of 7.73 and 14.50 mGy h-1 in front of 46 cm shield. The achieved design offers a suitable performance toward a compact high-flux neutron generator.

  5. High-power liquid-lithium target prototype for accelerator-based boron neutron capture therapy.

    PubMed

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Bisyakoev, M; Eliyahu, I; Feinberg, G; Hazenshprung, N; Kijel, D; Nagler, A; Silverman, I

    2011-12-01

    A prototype of a compact Liquid-Lithium Target (LiLiT), which will possibly constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals, was built. The LiLiT setup is presently being commissioned at Soreq Nuclear Research Center (SNRC). The liquid-lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power generated using a high-intensity proton beam (>10 kW), necessary for sufficient neutron flux. In off-line circulation tests, the liquid-lithium loop generated a stable lithium jet at high velocity, on a concave supporting wall; the concept will first be tested using a high-power electron beam impinging on the lithium jet. High intensity proton beam irradiation (1.91-2.5 MeV, 2-4 mA) will take place at Soreq Applied Research Accelerator Facility (SARAF) superconducting linear accelerator currently in construction at SNRC. Radiological risks due to the (7)Be produced in the reaction were studied and will be handled through a proper design, including a cold trap and appropriate shielding. A moderator/reflector assembly is planned according to a Monte Carlo simulation, to create a neutron spectrum and intensity maximally effective to the treatment and to reduce prompt gamma radiation dose risks. PMID:21459008

  6. Measurement of Neutrons Produced by Beam-Target Interactions via a Coaxial Plasma Accelerator

    NASA Astrophysics Data System (ADS)

    Cauble, Scott; Poehlmann, Flavio; Rieker, Gregory; Cappelli, Mark

    2011-10-01

    This poster presents a method to measure neutron yield from a coaxial plasma accelerator. Stored electrical energies between 1 and 19 kJ are discharged within a few microseconds across the electrodes of the coaxial gun, accelerating deuterium gas samples to plasma beam energies well beyond the keV energy range. The focus of this study is to examine the interaction of the plasma beam with a deuterated target by designing and fabricating a detector to measure neutron yield. Given the strong electromagnetic pulse associated with our accelerator, indirect measurement of neutrons via threshold-dependent nuclear activation serves as both a reliable and definitive indicator of high-energy particles for our application. Upon bombardment with neutrons, discs or stacks of metal foils placed near the deuterated target undergo nuclear activation reactions, yielding gamma-emitting isotopes whose decay is measured by a scintillation detector system. By collecting gamma ray spectra over time and considering nuclear cross sections, the magnitude of the original neutron pulse is inferred.

  7. Cross section for inelastic neutron ''acceleration'' by {sup 178}Hf{sup m2}

    SciTech Connect

    Karamian, S. A.; Carroll, J. J.

    2011-02-15

    The scattering of thermal neutrons from isomeric nuclei may include events in which the outgoing neutrons have increased kinetic energy. This process has been called inelastic neutron acceleration, or INNA, and occurs when the final nucleus, after emission of the neutron, is left in a state with lower energy than that of the isomer. The result, therefore, is an induced depletion of the isomer to the ground state. A cascade of several {gamma}'s must accompany the neutron emission to release the high angular momentum of the initial isomeric state. INNA was previously observed in a few cases, and the measured cross sections were only in modest agreement with theoretical estimates. The most recent measurement of an INNA cross section was {sigma}{sub INNA}=258{+-}58 b for neutron scattering by {sup 177}Lu{sup m}. In the present work, an INNA cross section of {sigma}{sub INNA}=168 {+-} 33 b was deduced from measurements of the total burnup of the high-spin, four-quasiparticle isomer {sup 178}Hf{sup m2} during irradiation by thermal neutrons. Statistical estimates for the probability of different reaction channels past neutron absorption were used in the analysis, and the deduced {sigma}{sub INNA} was compared to the theoretically predicted cross section.

  8. Space radiation accelerator experiments - The role of neutrons and light ions

    NASA Astrophysics Data System (ADS)

    Norbury, John W.; Slaba, Tony C.

    2014-10-01

    The importance of neutrons and light ions is considered when astronauts spend considerable time in thickly shielded regions of a spacecraft. This may be relevant for space missions both in and beyond low Earth orbit (LEO). In addition to heavy ion experiments at accelerators, it is suggested that an increased emphasis on experiments with lighter ions may be useful in reducing biological uncertainties.

  9. Experimental and theoretical evaluation of accelerator based epithermal neutron yields for BNCT

    NASA Astrophysics Data System (ADS)

    Wielopolski, L.; Ludewig, H.; Powell, J. R.; Raparia, D.; Alessi, J. G.; Alburger, D. E.; Zucker, M. S.; Lowenstein, D. I.

    1999-06-01

    At BNL, we have evaluated the beam current required to produce a clinical neutron beam for Boron Neutron Capture Therapy (BNCT) with an epithermal neutron flux of 1012n/cm2/hr. Experiments were carried out on a Van de Graaff accelerator at the Radiological Research Accelerator Facility (RARAF) at Columbia University. A thick Li target was irradiated by protons with energies from 1.8 to 2.5 MeV. The neutron spectra resulting from the 7Li(p,n)7Be reaction, followed by various filter configurations, were determined by measuring pulse height distributions with a gas filled proton recoil spectrometer. These distributions were unfolded into neutron energy spectra using the PSNS code, from which the required beam currents were estimated to be about 5 mA. Results are in good agreement with calculations using the MCNP-4A transport code. In addition comparison was also made between the neutron flux obtained at the Brookhaven Medical Research Reactor (where clinical trials of BNCT are ongoing), and measurements at RARAF, using a 10BF3 detector in a phantom. These results also support the requirement for about 5 mA beam current.

  10. Investigation of laser ion acceleration inside irradiated solid targets by neutron spectroscopy

    SciTech Connect

    Youssef, A.; Kodama, R.; Tampo, M.

    2006-03-15

    Origins and acceleration directions of accelerated ions inside solid LiF, CH-LiF, and LiF-CH targets irradiated by a 450 fs, 20 J, 1053 nm laser at an intensity of 3x10{sup 18} W/cm{sup 2} have been investigated by neutron spectroscopy. The irradiated targets generate neutrons through the reaction {sup 7}Li (p,n){sup 7}Be between accelerated protons and background {sup 7}Li ions inside the target. The produced neutron spectra observed from two different observation angles 20 deg. and 120 deg. to the target rear-side normal. From the measured and calculated spectra, by three-dimensional Monte Carlo code, the maximum energy, the total number, and the slope temperature of the accelerated ions are investigated. The results indicate that ions are not only accelerated from the front surface toward the rear surface, but also from the rear surface toward the front surface with comparable maximum energy and higher number.

  11. Calculations of neutron shielding data for 10-100 MeV proton accelerators.

    PubMed

    Chen, C C; Sheu, R J; Jian, S H

    2005-01-01

    The characteristics of neutron sources and their attenuation in concrete were investigated in detail for protons with energies ranging from 10 to 100 MeV striking on target materials of C, N, Al, Fe, Cu and W. A two-step approach was adopted: thick-target double-differential neutron yields were first calculated from the (p, xn) cross sections recommended in the ICRU Report 63; further, transport simulations of those neutrons in concrete were performed by using the FLUKA Monte Carlo code. The purpose of this study is to provide reasonably accurate parameters for shielding design for 10-100 MeV proton accelerators. Source terms and the corresponding attenuation lengths in concrete for several target materials are given as a function of proton energies and neutron emission angles. PMID:16604637

  12. Universality of the acceleration due to gravity on the surface of a rapidly rotating neutron star

    SciTech Connect

    AlGendy, Mohammad; Morsink, Sharon M.

    2014-08-20

    On the surface of a rapidly rotating neutron star, the effective centrifugal force decreases the effective acceleration due to gravity (as measured in the rotating frame) at the equator while increasing the acceleration at the poles due to the centrifugal flattening of the star into an oblate spheroid. We compute the effective gravitational acceleration for relativistic rapidly rotating neutron stars and show that for a star with mass M, equatorial radius R{sub e} , and angular velocity Ω, the deviations of the effective acceleration due to gravity from the nonrotating case take on a universal form that depends only on the compactness ratio M/R{sub e} , the dimensionless square of the angular velocity Ω{sup 2}R{sub e}{sup 3}/GM, and the latitude on the star's surface. This dependence is universal, in that it has very little dependence on the neutron star's equation of state. The effective gravity is expanded in the slow-rotation limit to show the dependence on the effective centrifugal force, oblate shape of the star, and the quadrupole moment of the gravitational field. In addition, an empirical fit and simple formula for the effective gravity is found. We find that the increase in the acceleration due to gravity at the poles is of the same order of magnitude as the decrease in the effective acceleration due to gravity at the equator for all realistic value of mass, radius, and spin. For neutron stars that spin with frequencies near 600 Hz, the difference between the effective gravity at the poles and the equator is about 20%.

  13. Systematic neutron guide misalignment for an accelerator-driven spallation neutron source

    NASA Astrophysics Data System (ADS)

    Zendler, C.; Bentley, P. M.

    2016-08-01

    The European Spallation Source (ESS) is a long pulse spallation neutron source that is currently under construction in Lund, Sweden. A considerable fraction of the 22 planned instruments extend as far as 75-150 m from the source. In such long beam lines, misalignment between neutron guide segments can decrease the neutron transmission significantly. In addition to a random misalignment from installation tolerances, the ground on which ESS is built can be expected to sink with time, and thus shift the neutron guide segments further away from the ideal alignment axis in a systematic way. These systematic errors are correlated to the ground structure, position of buildings and shielding installation. Since the largest deformation is expected close to the target, even short instruments might be noticeably affected. In this study, the effect of this systematic misalignment on short and long ESS beam lines is analyzed, and a possible mitigation by overillumination of subsequent guide sections investigated.

  14. High-sensitivity transuranic waste assay by simultaneous proton and thermal-neutron interrogation using an electron linear accelerator

    SciTech Connect

    Franks, L.A.; Pigg, J.L.; Caldwell, J.T.; Cates, M.R.; Kunz, W.E.; Noel, B.W.

    1982-01-01

    Simultaneous photon and neutron interrogation from electron linear accelerator pulses is used as the basis for a unique assay technique for transuranics. Both prompt and delayed neutrons from the induced fissions are counted on a single detection system, and the contributions from each interrogating flux are resolved. Detection limits (3 sigma) for /sup 239/Pu were estimated to be 3 mg for prompt fission neutrons and 6 mg for delayed neutrons. The technique also provides a clear distinction between fissile and fertile nuclides.

  15. The effect of a paraffin screen on the neutron dose at the maze door of a 15 MV linear accelerator

    SciTech Connect

    Krmar, M.; Kuzmanović, A.; Nikolić, D.; Kuzmanović, Z.; Ganezer, K.

    2013-08-15

    Purpose: The purpose of this study was to explore the effects of a paraffin screen located at various positions in the maze on the neutron dose equivalent at the maze door.Methods: The neutron dose equivalent was measured at the maze door of a room containing a 15 MV linear accelerator for x-ray therapy. Measurements were performed for several positions of the paraffin screen covering only 27.5% of the cross-sectional area of the maze. The neutron dose equivalent was also measured at all screen positions. Two simple models of the neutron source were considered in which the first assumed that the source was the cross-sectional area at the inner entrance of the maze, radiating neutrons in an isotropic manner. In the second model the reduction in the neutron dose equivalent at the maze door due to the paraffin screen was considered to be a function of the mean values of the neutron fluence and energy at the screen.Results: The results of this study indicate that the equivalent dose at the maze door was reduced by a factor of 3 through the use of a paraffin screen that was placed inside the maze. It was also determined that the contributions to the dosage from areas that were not covered by the paraffin screen as viewed from the dosimeter, were 2.5 times higher than the contributions from the covered areas. This study also concluded that the contributions of the maze walls, ceiling, and floor to the total neutron dose equivalent were an order of magnitude lower than those from the surface at the far end of the maze.Conclusions: This study demonstrated that a paraffin screen could be used to reduce the neutron dose equivalent at the maze door by a factor of 3. This paper also found that the reduction of the neutron dose equivalent was a linear function of the area covered by the maze screen and that the decrease in the dose at the maze door could be modeled as an exponential function of the product φ·E at the screen.

  16. Simulation of neutron production using MCNPX+MCUNED.

    PubMed

    Erhard, M; Sauvan, P; Nolte, R

    2014-10-01

    In standard MCNPX, the production of neutrons by ions cannot be modelled efficiently. The MCUNED patch applied to MCNPX 2.7.0 allows to model the production of neutrons by light ions down to energies of a few kiloelectron volts. This is crucial for the simulation of neutron reference fields. The influence of target properties, such as the diffusion of reactive isotopes into the target backing or the effect of energy and angular straggling, can be studied efficiently. In this work, MCNPX/MCUNED calculations are compared with results obtained with the TARGET code for simulating neutron production. Furthermore, MCUNED incorporates more effective variance reduction techniques and a coincidence counting tally. This allows the simulation of a TCAP experiment being developed at PTB. In this experiment, 14.7-MeV neutrons will be produced by the reaction T(d,n)(4)He. The neutron fluence is determined by counting alpha particles, independently of the reaction cross section. PMID:24132389

  17. Neutron activation system for spectral measurements of pulsed ion diode neutron production

    SciTech Connect

    Hanson, D.L.; Kruse, L.W.

    1980-02-01

    A neutron energy spectrometer has been developed to study intense ion beam-target interactions in the harsh radiation environment of a relativistic electron beam source. The main component is a neutron threshold activation system employing two multiplexed high efficiency Ge(Li) detectors, an annihilation gamma coincidence system, and a pneumatic sample transport. Additional constraints on the neutron spectrum are provided by total neutron yield and time-of-flight measurements. A practical lower limit on the total neutron yield into 4..pi.. required for a spectral measurement with this system is approx. 10/sup 10/ n where the neutron yield is predominantly below 4 MeV and approx. 10/sup 8/ n when a significant fraction of the yield is above 4 MeV. Applications of this system to pulsed ion diode neutron production experiments on Hermes II are described.

  18. Ultra-short ion and neutron pulse production

    DOEpatents

    Leung, Ka-Ngo; Barletta, William A.; Kwan, Joe W.

    2006-01-10

    An ion source has an extraction system configured to produce ultra-short ion pulses, i.e. pulses with pulse width of about 1 .mu.s or less, and a neutron source based on the ion source produces correspondingly ultra-short neutron pulses. To form a neutron source, a neutron generating target is positioned to receive an accelerated extracted ion beam from the ion source. To produce the ultra-short ion or neutron pulses, the apertures in the extraction system of the ion source are suitably sized to prevent ion leakage, the electrodes are suitably spaced, and the extraction voltage is controlled. The ion beam current leaving the source is regulated by applying ultra-short voltage pulses of a suitable voltage on the extraction electrode.

  19. Applications of compact accelerator-driven neutron sources: An updated assessment from the perspective of materials research in Italy

    SciTech Connect

    Andreani, C.; Anderson, I. S.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C. -K.; Senesi, R.

    2014-12-24

    In 2005 the International Atomic Energy Agency (IAEA) in Vienna published a report [1] on ‘Development Opportunities of Small and Medium Scale Accelerator Driven Neutron Sources’ which summarized the prospect of smaller sources in supporting the large spallation neutron sources for materials characterization and instrumentation, a theme advocated by Bauer, Clausen, Mank, and Mulhauser in previous publications [2-4]. In 2010 the Union for Compact Accelerator-driven Neutron Sources (UCANS) was established [5], galvanizing cross-disciplinary collaborations on new source and neutronics development and expanded applications based on both slow-neutron scattering and other neutron-matter interactions of neutron energies ranging from 10⁻⁶ to 10² MeV [6]. Here, we first cover the recent development of ongoing and prospective projects of compact accelerator-driven neutron sources (CANS) but concentrate on prospective accelerators currently proposed in Italy. Two active R&D topics, irradiation effects on electronics and cultural heritage studies, are chosen to illustrate the impact of state-of-the-art CANS on these programs with respect to the characteristics and complementarity of the accelerator and neutronics systems as well as instrumentation development.

  20. Applications of compact accelerator-driven neutron sources: An updated assessment from the perspective of materials research in Italy

    DOE PAGESBeta

    Andreani, C.; Anderson, I. S.; Carpenter, J. M.; Festa, G.; Gorini, G.; Loong, C. -K.; Senesi, R.

    2014-12-24

    In 2005 the International Atomic Energy Agency (IAEA) in Vienna published a report [1] on ‘Development Opportunities of Small and Medium Scale Accelerator Driven Neutron Sources’ which summarized the prospect of smaller sources in supporting the large spallation neutron sources for materials characterization and instrumentation, a theme advocated by Bauer, Clausen, Mank, and Mulhauser in previous publications [2-4]. In 2010 the Union for Compact Accelerator-driven Neutron Sources (UCANS) was established [5], galvanizing cross-disciplinary collaborations on new source and neutronics development and expanded applications based on both slow-neutron scattering and other neutron-matter interactions of neutron energies ranging from 10⁻⁶ to 10²more » MeV [6]. Here, we first cover the recent development of ongoing and prospective projects of compact accelerator-driven neutron sources (CANS) but concentrate on prospective accelerators currently proposed in Italy. Two active R&D topics, irradiation effects on electronics and cultural heritage studies, are chosen to illustrate the impact of state-of-the-art CANS on these programs with respect to the characteristics and complementarity of the accelerator and neutronics systems as well as instrumentation development.« less

  1. Secondary Neutron Production from Space Radiation Interactions: Advances in Model and Experimental Data Base Development

    NASA Technical Reports Server (NTRS)

    Heilbronn, Lawrence H.; Townsend, Lawrence W.; Braley, G. Scott; Iwata, Yoshiyuki; Iwase, Hiroshi; Nakamura, Takashi; Ronningen, Reginald M.; Cucinotta, Francis A.

    2003-01-01

    For humans engaged in long-duration missions in deep space or near-Earth orbit, the risk from exposure to galactic and solar cosmic rays is an important factor in the design of spacecraft, spacesuits, and planetary bases. As cosmic rays are transported through shielding materials and human tissue components, a secondary radiation field is produced. Neutrons are an important component of that secondary field, especially in thickly-shielded environments. Calculations predict that 50% of the dose-equivalent in a lunar or Martian base comes from neutrons, and a recent workshop held at the Johnson Space Center concluded that as much as 30% of the dose in the International Space Station may come from secondary neutrons. Accelerator facilities provide a means for measuring the effectiveness of various materials in their ability to limit neutron production, using beams and energies that are present in cosmic radiation. The nearly limitless range of beams, energies, and target materials that are present in space, however, means that accelerator-based experiments will not provide a complete database of cross sections and thick-target yields that are necessary to plan and design long-duration missions. As such, accurate nuclear models of neutron production are needed, as well as data sets that can be used to compare with, and verify, the predictions from such models. Improvements in a model of secondary neutron production from heavy-ion interactions are presented here, along with the results from recent accelerator-based measurements of neutron-production cross sections. An analytical knockout-ablation model capable of predicting neutron production from high-energy hadron-hadron interactions (both nucleon-nucleus and nucleus-nucleus collisions) has been previously developed. In the knockout stage, the collision between two nuclei result in the emission of one or more nucleons from the projectile and/or target. The resulting projectile and target remnants, referred to as

  2. Neutron dose calculation at the maze entrance of medical linear accelerator rooms.

    PubMed

    Falcão, R C; Facure, A; Silva, A X

    2007-01-01

    Currently, teletherapy machines of cobalt and caesium are being replaced by linear accelerators. The maximum photon energy in these machines can vary from 4 to 25 MeV, and one of the great advantages of these equipments is that they do not have a radioactive source incorporated. High-energy (E > 10 MV) medical linear accelerators offer several physical advantages over lower energy ones: the skin dose is lower, the beam is more penetrating, and the scattered dose to tissues outside the target volume is smaller. Nevertheless, the contamination of undesirable neutrons in the therapeutic beam, generated by the high-energy photons, has become an additional problem as long as patient protection and occupational doses are concerned. The treatment room walls are shielded to attenuate the primary and secondary X-ray fluence, and this shielding is generally adequate to attenuate the neutrons. However, these neutrons are scattered through the treatment room maze and may result in a radiological problem at the door entrance, a high occupancy area in a radiotherapy facility. In this article, we used MCNP Monte Carlo simulation to calculate neutron doses in the maze of radiotherapy rooms and we suggest an alternative method to the Kersey semi-empirical model of neutron dose calculation at the entrance of mazes. It was found that this new method fits better measured values found in literature, as well as our Monte Carlo simulated ones. PMID:17005540

  3. Measurements of Accelerator-Produced Leakage Neutron and Photon Transmission through Concrete

    SciTech Connect

    Nelson, Walter R

    2002-07-04

    Optimum shielding of the radiation from particle accelerators requires knowledge of the attenuation characteristics of the shielding material. The most common material for shielding this radiation is concrete, which can be made using various materials of different densities as aggregates. These different concrete mixes can have very different attenuation characteristics. Information about the attenuation of leakage photons and neutrons in ordinary and heavy concrete is, however, very limited. To increase our knowledge and understanding of the radiation attenuation in concrete of various compositions, we have performed measurements of the transmission of leakage radiation, photons and neutrons, from a Varian Clinac 2100C medical linear accelerator operating at maximum electron energies of 6 and 18 MeV. We also calculated, using Monte Carlo techniques, the leakage neutron spectra and its transmission through concrete. The results of these measurements and calculations extend the information currently available for designing shielding for medical electron accelerators. Photon transmission characteristics depend more on the manufacturer of the concrete than on the atomic composition. A possible cause for this effect is a non-uniform distribution of the high density aggregate, typically iron, in the concrete matrix. Errors in estimated transmission of photons can exceed a factor of three, depending on barrier thickness, if attenuation in high-density concrete is simply scaled from that of normal density concrete. We found that neutron transmission through the high-density concretes can be estimated most reasonably and conservatively by using the linear tenth-value layer of normal concrete if specific values of the tenth-value layer of the high-density concrete are not known. The reason for this is that the neutron transmission depends primarily on the hydrogen content of the concrete, which does not significantly depend on concrete density. Errors of factors of two to

  4. Accelerator for the production of tritium (APT)

    SciTech Connect

    Wilson, M.T.; Bhatia, T.S.; Guy, F.W.; Neuschaefer, G.H.; Wangler, T.P.; Young, L.M.

    1989-01-01

    A collaborative study by Los Alamos and Brookhaven National Laboratories, supported by the Westinghouse Hanford Company, investigating a facility to produce tritium for the nation's defense needs indicates that a 1.6-GeV, 250-mA proton accelerator is required. A reference design of this accelerator starts with two parallel 125-keV injectors feeding 350-MHz radio-frequency quadrupoles (RFQ) that funnel at 2.5 MeV into a 700-MHz drift-tube linac (DTL). The DTL injects at 100 MeV into a 1400-MHz side-coupled linac (SCL). The accelerator will cost about $1.2 B and require 746 MW of electricity. 3 refs., 3 tabs.

  5. Production of ultra cold neutrons by a doppler shifter with pulsed neutrons at J-PARC

    NASA Astrophysics Data System (ADS)

    Mishima, K.; Imajo, S.; Hino, M.; Ino, T.; Iwashita, Y.; Katayama, R.; Kitaguchi, M.; Oda, T.; Shimizu, H. M.; Utsuro, M.; Yamashita, S.; Yoshioka, T.

    2014-07-01

    Ultracold neutrons (UCNs) are neutrons whose kinetic energy is around a few hundred nanoelectronvolts. Neutrons with such small kinetic energy can be trapped in a material vessel or magnetic fields. Because of these unique characteristics, UCNs are used for some important experiments of fundamental physics. The Doppler shifter is a device to produce UCN by slowing them down by the reflection on a mirror moving with half of the velocity of incoming neutrons. A Doppler shifter using a quadruple-stack of monochromatic supermirrors that reflects neutrons with a velocity around 68m/s [1, Hino et al.(2010)] was fabricated, and operated with a pulsed neutron source of J-PARC. An important feature of the Doppler shifter is the use of a pulsed neutron beam. Unlike in continuous neutron beams, the neutron velocity can be selected by choosing a time slice in a pulsed neutron bunch. Thus the UCN production improves by ~80 times in the case of J-PARC. We successfully produced the UCNs by the Doppler shifter: the measured UCN production rate is consistent with the simulations.

  6. Measurements of Neutron Induced Cross Sections at the Oak Ridge Electron Linear Accelerator

    SciTech Connect

    Guber, K.H.; Harvey, J.A.; Hill, N.W.; Koehler, P.E.; Leal, L.C.; Sayer, R.O.; Spencer, R.R.

    1999-09-20

    We have used the Oak Ridge Electron Linear Accelerator (ORELA) to measure neutron total and the fission cross sections of 233U in the energy range from 0.36 eV to ~700 keV. We report average fission and total cross sections. Also, we measured the neutron total cross sections of 27Al and Natural chlorine as well as the capture cross section of Al over an energy range from 100 eV up to about 400 keV.

  7. Additive effect of BPA and Gd-DTPA for application in accelerator-based neutron source.

    PubMed

    Yoshida, F; Yamamoto, T; Nakai, K; Zaboronok, A; Matsumura, A

    2015-12-01

    Because of its fast metabolism gadolinium as a commercial drug was not considered to be suitable for neutron capture therapy. We studied additive effect of gadolinium and boron co-administration using colony forming assay. As a result, the survival of tumor cells with additional 5 ppm of Gd-DTPA decreased to 1/10 compared to the cells with boron only. Using gadolinium to increase the effect of BNCT instead of additional X-ray irradiation might be beneficial, as such combination complies with the short-time irradiation regimen at the accelerator-based neutron source. PMID:26242560

  8. Neutron-induced electronic failures around a high-energy linear accelerator

    SciTech Connect

    Kry, Stephen F.; Johnson, Jennifer L.; White, R. Allen; Howell, Rebecca M.; Kudchadker, Rajat J.; Gillin, Michael T.

    2011-01-15

    Purpose: After a new in-vault CT-on-rails system repeatedly malfunctioned following use of a high-energy radiotherapy beam, we investigated the presence and impact of neutron radiation on this electronic system, as well as neutron shielding options. Methods: We first determined the CT scanner's failure rate as a function of the number of 18 MV monitor units (MUs) delivered. We then re-examined the failure rate with both 2.7-cm-thick and 7.6-cm-thick borated polyethylene (BPE) covering the linac head for neutron shielding. To further examine shielding options, as well as to explore which neutrons were relevant to the scanner failure, Monte Carlo simulations were used to calculate the neutron fluence and spectrum in the bore of the CT scanner. Simulations included BPE covering the CT scanner itself as well as covering the linac head. Results: We found that the CT scanner had a 57% chance of failure after the delivery of 200 MUs. While the addition of neutron shielding to the accelerator head reduced this risk of failure, the benefit was minimal and even 7.6 cm of BPE was still associated with a 29% chance of failure after the delivery of 200 MU. This shielding benefit was achieved regardless of whether the linac head or CT scanner was shielded. Additionally, it was determined that fast neutrons were primarily responsible for the electronic failures. Conclusions: As illustrated by the CT-on-rails system in the current study, physicists should be aware that electronic systems may be highly sensitive to neutron radiation. Medical physicists should therefore monitor electronic systems that have not been evaluated for potential neutron sensitivity. This is particularly relevant as electronics are increasingly common in the therapy vault and newer electronic systems may exhibit increased sensitivity.

  9. Thermal-hydraulic design of the target/blanket for the accelerator production of tritium conceptual design

    SciTech Connect

    Willcutt, G.J.E. Jr.; Kapernick, R.J.

    1997-11-01

    A conceptual design was developed for the target/blanket system of an accelerator-based system to produce tritium. The target/blanket system uses clad tungsten rods for a spallation target and clad lead rods as a neutron multiplier in a blanket surrounding the target. The neutrons produce tritium in {sup 3}He, which is contained in aluminum tubes located in the decoupler and blanket regions. This paper presents the thermal-hydraulic design of the target, decoupler, and blanket developed for the conceptual design of the Accelerator Production of Tritium Project, and demonstrates there is adequate margin in the design at full power operation.

  10. Benchmarking shielding simulations for an accelerator-driven spallation neutron source

    NASA Astrophysics Data System (ADS)

    Cherkashyna, Nataliia; DiJulio, Douglas D.; Panzner, Tobias; Rantsiou, Emmanouela; Filges, Uwe; Ehlers, Georg; Bentley, Phillip M.

    2015-08-01

    The shielding at an accelerator-driven spallation neutron facility plays a critical role in the performance of the neutron scattering instruments, the overall safety, and the total cost of the facility. Accurate simulation of shielding components is thus key for the design of upcoming facilities, such as the European Spallation Source (ESS), currently in construction in Lund, Sweden. In this paper, we present a comparative study between the measured and the simulated neutron background at the Swiss Spallation Neutron Source (SINQ), at the Paul Scherrer Institute (PSI), Villigen, Switzerland. The measurements were carried out at several positions along the SINQ monolith wall with the neutron dosimeter WENDI-2, which has a well-characterized response up to 5 GeV. The simulations were performed using the Monte-Carlo radiation transport code geant4, and include a complete transport from the proton beam to the measurement locations in a single calculation. An agreement between measurements and simulations is about a factor of 2 for the points where the measured radiation dose is above the background level, which is a satisfactory result for such simulations spanning many energy regimes, different physics processes and transport through several meters of shielding materials. The neutrons contributing to the radiation field emanating from the monolith were confirmed to originate from neutrons with energies above 1 MeV in the target region. The current work validates geant4 as being well suited for deep-shielding calculations at accelerator-based spallation sources. We also extrapolate what the simulated flux levels might imply for short (several tens of meters) instruments at ESS.

  11. Experimental study of ultracold neutron production in pressurized superfluid helium

    NASA Astrophysics Data System (ADS)

    Schmidt-Wellenburg, P.; Bossy, J.; Farhi, E.; Fertl, M.; Leung, K. K. H.; Rahli, A.; Soldner, T.; Zimmer, O.

    2015-08-01

    We investigate experimentally the pressure dependence of the production of ultracold neutrons (UCNs) in superfluid helium in the range from saturated vapor pressure to 20 bar. A neutron velocity selector allows the separation of underlying single-phonon and multiphonon processes by varying the incident cold neutron (CN) wavelength in the range from 3.5 to 10 Å. The predicted pressure dependence of UCN production derived from inelastic neutron scattering data is confirmed for the single-phonon excitation. For multiphonon-based UCN production we found no significant dependence on pressure, whereas calculations from inelastic neutron scattering data predict an increase of 43(6)% at 20 bar relative to saturated vapor pressure. From our data we conclude that applying pressure to superfluid helium does not increase the overall UCN production rate at a typical CN guide.

  12. Evaluation of neutron dose in the maze of medical electron accelerators.

    PubMed

    Carinou, E; Kamenopoulou, V; Stamatelatos, I E

    1999-12-01

    MCNP code was used to simulate neutron and prompt gamma ray transport for a range of maze geometrical parameters, wall composition, and wall surface lining. Verification measurements were performed at two medical electron accelerator facilities. A very good agreement was observed between the results of the measurements and the MCNP simulation. MCNP code results were compared with the results of analytical equations used for the calculation of maze effectiveness, derived by Kersey and McCall. A good agreement exists between the simulation results and the results of the analytical methods for maze lengths longer than 8.5 m. However, the results of the present study showed that for shorter maze lengths, Kersey's method tended to overestimate neutron dose at the door entrance, whereas McCall's method with the neutron room scattered correction applied, showed an underestimation of neutron dose. Furthermore, according to MCNP simulation results, the use of barytes concrete instead of standard concrete as room shielding material, reduced neutron dose at the door entrance by about 20%. Finally, it was shown that lining with layers of wood and borated polyethylene significantly reduced the neutron dose at the door entrance by 45% and 65%, respectively. PMID:10619233

  13. Use of accelerator mass spectrometry in the dosimetry of Hiroshima neutrons

    NASA Astrophysics Data System (ADS)

    Straume, T.; Finkel, R. C.; Eddy, D.; Kubik, P. W.; Gove, H. E.; Sharma, P.; Fujita, S.; Hoshi, M.

    1990-12-01

    A substantial discrepancy exists between the measured values for thermal neutron activation and the values calculated using the new A-bomb dosimetry system, DS86. As part of a joint US-Japan effort aimed at resolving this discrepancy, we have shown that 36Cl/Cl in mineral samples (i.e., concrete, granite, tiles) can be measured with sufficient precision using accelerator mass spectrometry (AMS) to quantify the very low thermal neutron activation levels at distances between 1000 and 2000 m from the hypocenter in Hiroshima. Our initial measurement results show that activation of Cl by the bomb neutrons disagree with calculations based on the new DS86 dosimetry system (measurements of 36Cl at 1450 m from the hypocenter indicate thermal neutron activation that is ˜15 times higher than obtained from DS86 calculations; discrepancies are even larger at 1606 m). This is a preliminary report of work in progress. The principal objectives of this work are to reconstruct the thermal neutron fluence as a function of distance from the hypocenters in both Hiroshima and Nagasaki using 36Cl/Cl and obtain information about fast neutron fluence.

  14. Overview of secondary neutron production relevant to shielding in space.

    PubMed

    Heilbronn, L; Nakamura, T; Iwata, Y; Kurosawa, T; Iwase, H; Townsend, L W

    2005-01-01

    An overview of experimental secondary neutron measurements relevant to space-related activities is presented. Stopping target yields and cross section measurements conducted at particle accelerators using heavy ions with energies > 100 MeV per nucleon are discussed. PMID:16604615

  15. Development of a dedicated superconducting accelerator for positron production

    NASA Astrophysics Data System (ADS)

    O'Rourke, B. E.; Oshima, N.; Kuroda, R.; Suzuki, R.; Ohdaira, T.; Kinomura, A.; Hayashizaki, N.; Minehara, E.; Yamauchi, H.; Fukamizu, Y.; Shikibu, M.; Kawamoto, T.; Minehara, Y.

    2011-01-01

    We report on the current status of a project to develop a dedicated superconducting accelerator for slow positron production at AIST. Two 500 MHz, 5 cell cavities will form the basis of the new accelerator. Initial set-up and preliminary design activities are reported.

  16. Neutron Induced Reactions with the 17 Mev Facility at the Athens Tandem Accelerator NCSR 'Demokritos'

    NASA Astrophysics Data System (ADS)

    Vlastou, R.; Kalamara, A.; Serris, M.; Diakaki, M.; Kokkoris, M.; Paneta, V.; Axiotis, M.; Lagoyannis, A.

    In the 5.5 MV tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" monoenergetic neutron beams have been produced in the energy range∼ 15-20 MeV using anew Ti-tritiated target of 373 GBq activity, by means of the 3H(d,n)4He reaction. The corresponding deuteron beam energies obtained from the accelerator, were in the 1.5-4.5MeV range.The maximum flux has been determined to be of the order of 106 n/cm2 s, implementing reference reactions. The 17.1MeV neutron beam has been used for the measurement of 197Au(n,2n) reaction cross section. Theoretical calculations have been performed via the statistical model code EMPIRE and compared to the experimental data of the present work and data from literature.

  17. Neutron production in several americium compounds

    SciTech Connect

    Shores, E. F.

    2004-01-01

    Americium, like other alpha emitting actinides, may indirectly produce neutrons when combined with light target materials. These (alpha,n) reaction neutrons, along with well known photon lines, have been an advantage of the {sup 241}Am isotope for diverse applications such as radiography, thickness gauges, neutron sources, and even common household smoke detectors. To characterize these sources, the SOURCES code was used to calculate neutron yields and spectra from {sup 241}Am metal, americium oxide, and americium aluminum alloys. Such information may be used as source terms for future transport problems (e.g. shielding calculations). Table 1 contains neutron yields for six americium configurations. The metal, oxides, and alloys were run as homogeneous problems while the interface case was run in both two- and three-region interface modes.

  18. Review of Activities using the Pulsed Neutron Facility and 2.5-GeV Electron Linac at Pohang Accelerator Laboratory

    SciTech Connect

    Kim, Guinyun; Lee, Manwoo; Kim, Kyung Sook; Yang, Sungchul; Kim, Eunae; Shvetshov, Valery; Cho, Moo-Hyun; Naik, Haladhara

    2011-12-13

    We report on activities using a pulsed neutron facility consisting of an electron linear accelerator, a water-cooled Ta target with a water moderator, and a 12 m time-of-flight path. It is possible to measure neutron total cross sections in the neutron energy range from 0.01 eV to a few hundred eV by using the neutron time-of-flight method; photo-neutron cross sections can also measure by using the bremsstrahlung from the electron linac. A {sup 6}LiZnS(Ag) glass scintillator was used as a neutron detector. The neutron flight path from the water-cooled Ta target to the neutron detector was 12.1 m. In this paper, we report total cross sections of Nb and also resonance parameters obtained using the SAMMY fitting program. The present results are compared with the previous experimental results and the evaluated data in ENDF/B-VII. We also report on the mass-yield distribution of fission products in the 2.5-GeV bremsstrahlung-induced fission of {sup nat}Pb and {sup 209}Bi measured at the 2.5-GeV electron linac using a recoil catcher and an off-line {gamma}-ray spectrometric technique.

  19. Effect of Driver Impedance on Dense Plasma Focus Z-Pinch Neutron Yield and Beam Acceleration

    NASA Astrophysics Data System (ADS)

    Sears, J.; Link, A.; Ellsworth, J.; Falabella, S.; Rusnak, B.; Tang, V.; Schmidt, A.; Welch, D.

    2014-10-01

    We explore the effect of driver characteristics on dense plasma focus (DPF) neutron yield and beam acceleration using particle-in-cell (PIC) simulations of a kJ-scale DPF. Our PIC simulations are fluid for the run-down phase and transition to fully kinetic for the pinch phase. The anode-cathode boundary is driven by a circuit model of the capacitive driver, including system inductance, the load of the railgap switches, the guard resistors, and the coaxial transmission line parameters. Simulations are benchmarked to measurements of a table top kJ DPF experiment with neutron yield measured with He3-based detectors. Simulated neutron yield scales approximately with the fourth power of peak current, I4. We also probe the accelerating fields by measuring the acceleration of a 4 MeV deuteron beam and by measuring the DPF self-generated beam energy distribution, finding gradients higher than 50 MV/m. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (11-ERD-063) at LLNL.

  20. An epithermal neutron source for BNCT based on an ESQ-accelerator

    SciTech Connect

    Ludewigt, B.A.; Chu, W.T.; Donahue, R.J.; Kwan, J.; Phillips, T.L.; Reginato, L.L.; Wells, R.P.

    1997-07-01

    An accelerator-based BNCT facility is under development at the Lawrence Berkeley National Laboratory. Neutrons will be produced via the {sup 7}Li(p,n) reaction at proton energies of about 2.5 MeV with subsequent moderation and filtering for shaping epithermal neutron beams for BNCT. Moderator, filter, and shielding assemblies have been modeled using MCNP. Head-phantom dose distributions have been calculated using the treatment planning software BNCT{_}RTPE. The simulation studies have shown that a proton beam current of {approximately} 20 mA is required to deliver high quality brain treatments in about 40 minutes. The results also indicate that significantly higher doses can be delivered to deep-seated tumors in comparison to the Brookhaven Medical Research Reactor beam. An electrostatic quadrupole (ESQ) accelerator is ideally suited to provide the high beam currents desired. A novel power supply utilizing the air-coupled transformer concept is under development. It will enable the ESQ-accelerator to deliver proton beam currents exceeding 50 mA. A lithium target has been designed which consists of a thin layer of lithium on an aluminum backing. Closely spaced, narrow coolant passages cut into the aluminum allow the removal of a 50kW heat-load by convective water cooling. The system under development is suitable for hospital installation and has the potential for providing neutron beams superior to reactor sources.

  1. Measurements of spin observables in pseudo-scalar meson photo-production using polarized neutrons in solid HD

    SciTech Connect

    Kageya, Tsuneo

    2014-01-01

    A measurement of psuedo-scalar meson photo production from longitudinally polarized solid HD has been carried out with the CLAS at Thomas Jefferson National Accelerator Facility (Jlab) with circularly and linearly polarized photon beams. Its aim is to measure a complete set of spin observables for the neutron simultaneously from the same experiment. As a polarized neutron, deutron in HD was used. Preliminary asymmetries are shown for the {pi}{sup -} channel.

  2. Measurements of Spin Observables in Single Pion Photo-Production from Polarized Quasi-Free Neutrons in Solid HD

    NASA Astrophysics Data System (ADS)

    Kageya, Tsuneo

    Abstract Psuedo-scalar meson photo production measurements have been carried out with longitudinally-polarized neutrons using the circularly and linearly polarized photon beams and the CLAS at Thomas Jefferson National Accelerator Facility (Jlab). The experiment aims to obtain a complete set of spin observables on an effective neutron target using D in HD. Preliminary E and Σ asymmetries for the exclusive reaction, γ + n(p) → π- + p(p), are discussed.

  3. Measurements of spin observables in pseudo-scalar meson photo-production using polarized neutrons in solid HD

    NASA Astrophysics Data System (ADS)

    Kageya, T.

    2014-01-01

    A measurement of psuedo-scalar meson photo production from longitudinally polarized solid HD has been carried out with the CLAS at Thomas Jefferson National Accelerator Facility (Jlab) with circularly and linearly polarized photon beams. Its aim is to measure a complete set of spin observables for the neutron simultaneously from the same experiment. As a polarized neutron, deutron in HD was used. Preliminary asymmetries are shown for the π- channel.

  4. Accelerator production of tritium plant design and supporting engineering development and demonstration work

    SciTech Connect

    Lisowski, P.W.

    1997-11-01

    Tritium is an isotope of hydrogen with a half life of 12.3 years. Because it is essential for US thermonuclear weapons to function, tritium must be periodically replenished. Since K reactor at Savannah River Site stopped operating in 1988, tritium has been recycled from dismantled nuclear weapons. This process is possible only as long as many weapons are being retired. Maintaining the stockpile at the level called for in the present Strategic Arms Reduction Treaty (START-I) will require the Department of Energy to have an operational tritium production capability in the 2005--2007 time frame. To make the required amount of tritium using an accelerator based system (APT), neutrons will be produced through high energy proton reactions with tungsten and lead. Those neutrons will be moderated and captured in {sup 3}He to make tritium. The APT plant design will use a 1,700 MeV linear accelerator operated at 100 mA. In preparation for engineering design, starting in October 1997 and subsequent construction, a program of engineering development and demonstration is underway. That work includes assembly and testing of the first 20 MeV of the low energy plant linac at 100 mA, high-energy linac accelerating structure prototyping, radiofrequency power system improvements, neutronic efficiency measurements, and materials qualifications.

  5. Target/Blanket Design for the Accelerator Production of Tritium Plant

    SciTech Connect

    Cappiello, M. W.

    1997-12-31

    The Accelerator Production of Tritium Target/Blanket (T/B) system is comprised of the T/B assembly and the attendant heat removal systems. The T/B assembly produces tritium using a high energy proton beam, and a spallation neutron source. The supporting heat removal systems safely remove the heat deposited by the proton beam during both normal and off-normal conditions. All systems reside within the T/B building, which is located at the end of a linear accelerator. Protons are accelerated to an energy of 1700 MeV at a current of 100 mA and are directed onto the T/B assembly. The protons interact with tungsten and lead nuclei to produce neutrons through the process of nuclear spallation. Neutron capture in {sup 3}He gas produces tritium which is removed on a continual basis in an adjacent Tritium Separation Facility (TSF). The T/B assembly is modular to allow for replacement of spent components and minimization of waste. Systems and components are designed with safety as a primary consideration to minimize risk to the workers and the public.

  6. Pulsed ultra-cold neutron production using a Doppler shifter at J-PARC

    NASA Astrophysics Data System (ADS)

    Imajo, S.; Mishima, K.; Kitaguchi, M.; Iwashia, Y.; Yamada, N. L.; Hino, M.; Oda, T.; Ino, T.; Shimizu, H. M.; Yamashita, S.; Katayama, R.

    2016-01-01

    We have constructed a Doppler-shifter-type pulsed ultra-cold neutron (UCN) source at the Materials and Life Science Experiment Facility of the Japan Proton Accelerator Research Complex. Very cold neutrons (VCNs) with 136 m s^{-1} velocity in a neutron beam supplied by a pulsed neutron source are decelerated by reflection on an m=10 wide-band multilayer mirror, yielding pulsed UCNs. The mirror is fixed to the tip of a 2000 rpm rotating arm moving with 68 m s^{-1} velocity in the same direction as the VCNs. The repetition frequency of the pulsed UCNs is 8.33 Hz and the time width of the pulse at production is 4.4 ms. In order to increase the UCN flux, a supermirror guide, wide-band monochromatic mirrors, focus guides, and a UCN extraction guide have been newly installed or improved. The 1 MW-equivalent count rate of the output neutrons with longitudinal wavelengths longer than 58 nm is 1.6 × 102 cps, while that of the true UCNs is 80 cps. The spatial density at production is 1.4 UCN cm^{-3}. This new UCN source enables us to research and develop apparatuses necessary for the investigation of the neutron electric dipole moment.

  7. Neutron production from ultrashort pulse lasers using linear and circular polarization

    NASA Astrophysics Data System (ADS)

    Davis, J.; Petrov, G. M.

    2011-07-01

    An implicit 2D3V particle-in-cell code is used to study proton and deuteron acceleration from an ultrathin CD foil with thickness between 20 and 200 nm using linear and circular polarization. The proton and deuteron beams drive nuclear fusion reactions from converter foils in a pitcher-catcher set-up. The neutron yield for three representative reactions d - d, d - Li, and p - Li has been calculated analytically using the total neutron production cross section and ion stopping power. For linear polarization, maximum normalized neutron yield of Y-d-d=3.4×106, Y-d-Li=3.2×107, and Y-p-Li=6.8×106 neutrons/J laser energy has been calculated at the optimum foil thickness of 50 nm. For circular polarization, the optimum foil thickness is 20 nm, for which the corresponding neutron yields are Y-d-d=1.9×106, Y-d-Li=2.0×107, and Y-p-Li=2.7×106, respectively. The laser polarization strongly affects the neutron production; for our regime, i.e., intensity I=1×1021 W/cm2, pulse duration τFWHM=30 fs, and laser energy ɛlaser=3.8 J, both the conversion efficiency of laser energy into ion kinetic energy and neutron yield are higher for linear polarization. Only for ultrathin (˜20 nm) foils in the radiation pressure acceleration regime, circular and linear polarizations yield comparable results.

  8. Optimisation of the manufacturing process of tritide and deuteride targets used for neutron production

    NASA Astrophysics Data System (ADS)

    Monnin, Carole; Bach, Pierre; Tulle, Pierre Alain; van Rompay, Marc; Ballanger, Anne

    2002-03-01

    As a neutron tube manufacturer, SODERN is now in charge of manufacturing tritium targets for accelerators, in cooperation with CEA/DAM/DTMN in Valduc. Specific deuterium and tritium targets are manufactured on request, according to the requirements of the users, starting from titanium targets on copper substrates, and going to more sophisticated devices. The range of possible uses is wide, including thin targets for neutron calibration, thick targets with controlled loading of deuterium and tritium, rotating targets or large size rotating targets for higher lifetimes. The activity of the targets ranges from 3.7×10 10 to 3.7×10 13 Bq (1-1000 Ci), the diameter being up to 30 cm. Sodern and the CEA/Valduc centre have developed different technologies for tritium target manufacture, allowing the selection of the best configuration for each kind of use. In order to optimize the production of high energy neutrons, the performance of tritide and deuteride titanium targets made by different processes has been studied experimentally by bombardment with 120 and 350 kV deuterons provided by electrostatic accelerators. It is then possible to optimize either neutron output or lifetime and stability or thermal behaviour. The importance of the deposit evaporation conditions on the efficiency of neutron emission is clearly demonstrated, as well as the thermomechanical stability of the Ti thin film under deuteron bombardment. The main parameters involved in the target performance are discussed from a thermodynamical approach.

  9. Dosimetric characterization of the irradiation cavity for accelerator-based in vivo neutron activation analysis.

    PubMed

    Byun, S H; Pejović-Milić, A; McMaster, S; Matysiak, W; Aslam; Liu, Z; Watters, L M; Prestwich, W V; McNeill, F E; Chettle, D R

    2007-03-21

    A neutron irradiation cavity for in vivo activation analysis has been characterized to estimate its dosimetric specifications. The cavity is defined to confine irradiation to the hand and modifies the neutron spectrum produced by a low energy accelerator neutron source to optimize activation per dose. Neutron and gamma-ray dose rates were measured with the microdosimetric technique using a tissue-equivalent proportional counter at the hand irradiation site and inside the hand access hole. For the outside of the cavity, a spherical neutron dose equivalent meter and a Farmer dosemeter were employed instead due to the low intensity of the radiation field. The maximum dose equivalent rate at the outside of the cavity was 2.94 microSv/100 microA min, which is lower by a factor of 1/2260 than the dose rate at the hand irradiation position. The local dose contributions from a hand, an arm and the rest of a body to the effective dose rate were estimated to be 1.73, 0.782 and 2.94 microSv/100 microA min, respectively. For the standard irradiation protocol of the in vivo hand activation, 300 microA min, an effective dose of 16.3 microSv would be delivered. PMID:17455391

  10. Production of an Accelerated Oxygen-14 Beam

    SciTech Connect

    Powell, James; O'Neil, James P.; Cerny, Joseph

    2002-05-03

    BEARS is an ongoing project to provide a light-ion radioactive-beam capability at the 88-Inch Cyclotron at LBNL. Light radioactive isotopes are produced at a 10 MeV proton medical cyclotron, transported 350 m via a high-speed gas transport capillary, cryogenically separated, and injected into the 88-Inch Cyclotron's ion source. The first radioactive beam successfully accelerated was Carbon-11 and beams of intensity more than 108 ions/sec have been utilized for experiments. Development of Oxygen-14 as the second BEARS beam presented considerable technical challenges, both due to its short half-life of 71 seconds and the radiation chemistry of oxygen in the target. The usual techniques developed for medical uses of Oxygen-15 involve the addition of significant amounts of carrier oxygen, something that would overload the ion source. As a solution, Oxygen-14 is produced as water in a carrier-free form, and is chemically converted in two steps to carbon dioxide, a form readily usable by the BEARS. This system has been built and is operational, and initial tests of accelerating an Oxygen-14 beam have been performed.

  11. Production of an accelerated oxygen-14 beam

    NASA Astrophysics Data System (ADS)

    Powell, J.; O'Neil, J. P.; Cerny, Joseph

    2003-05-01

    BEARS is an ongoing project to provide a light-ion radioactive-beam capability at the 88-Inch Cyclotron at LBNL. Light radioactive isotopes are produced at a 10 MeV proton medical cyclotron, transported 350 m via a high-speed gas transport capillary, cryogenically separated, and injected into the 88-Inch Cyclotron's ion source. The first radioactive beam successfully accelerated was carbon-11 and beams of intensity more than 10 8 ions/s have been utilized for experiments. Development of oxygen-14 as the second BEARS beam presented considerable technical challenges, both due to its short half-life of 71 s and the radiation chemistry of oxygen in the target. The usual techniques developed for medical uses of oxygen-15 involve the addition of significant amounts of carrier oxygen, something that would overload the ion source. As a solution, oxygen-14 is produced as water in a carrier-free form, and is chemically converted in two steps to carbon dioxide, a form readily usable by the BEARS. This system has been built and is operational, and initial tests of accelerating an oxygen-14 beam have been performed.

  12. Calculates Neutron Production in Canisters of High-level Waste

    1993-01-15

    ALPHN calculates the (alpha,n) neutron production rate of a canister of vitrified high-level waste. The user supplies the chemical composition of the glass or glass-ceramic and the curies of the alpha-emitting actinides present. The output of the program gives the (alpha,n) neutron production of each actinide in neutrons per second and the total for the canister. The (alpha,n) neutron production rates are source terms only; that is, they are production rates within the glass andmore » do not take into account the shielding effect of the glass. For a given glass composition, the user can calculate up to eight cases simultaneously; these cases are based on the same glass composition but contain different quantities of actinides per canister.« less

  13. Extending studies of the fusion of heavy nuclei to the neutron rich region using accelerated radioactive ion beams.

    SciTech Connect

    Shapira, Dan

    2011-01-01

    One of the stated goals for proposed and existing facilities that produce and accelerate radioactive ion beams is to explore and achieve a new understanding of the reactions mechanisms leading to the synthesis of the heaviest nuclei. Nuclear synthesis of two large nuclei into a single entity is a complex multistep process. The beam intensities of radioactive ions accelerated at present day facilities are not sufficient to synthesize super heavy elements. However the study of the iso-spin dependence of nuclear synthesis and the many processes competing with it can be carried out at present day facilities. Of special interest are cases where the interacting nuclei and the synthesized product are extremely neutron-rich. The effects of neutron excess on the reaction processes leading to the formation of the synthesized nucleus that emerged in earlier studies are poorly understood and sometimes counter intuitive. Results from measurements performed at HRIBF, as well as our plans for future measurements and the equipment being prepared will be presented.

  14. Production of neutrons from interactions of GCR-like particles

    NASA Technical Reports Server (NTRS)

    Heilbronn, L.; Frankel, K.; Holabird, K.; Zeitlin, C.; McMahan, M. A.; Rathbun, W.; Cronqvist, M.; Gong, W.; Madey, R.; Htun, M.; Elaasar, M.; Anderson, B. D.; Baldwin, A. R.; Jiang, J.; Keane, D.; Scott, A.; Shao, Y.; Watson, J. W.; Zhang, W. M.; Galonsky, A.; Ronningen, R.; Zecher, P.; Kruse, J.; Wang, J.; Miller, J. (Principal Investigator)

    1998-01-01

    In order to help assess the risk to astronauts due to the long-term exposure to the natural radiation environment in space, an understanding of how the primary radiation field is changed when passing through shielding and tissue materials must be obtained. One important aspect of the change in the primary radiation field after passing through shielding materials is the production of secondary particles from the breakup of the primary. Neutrons are an important component of the secondary particle field due to their relatively high biological weighting factors, and due to their relative abundance, especially behind thick shielding scenarios. Because of the complexity of the problem, the estimation of the risk from exposure to the secondary neutron field must be handled using calculational techniques. However, those calculations will need an extensive set of neutron cross section and thicktarget neutron yield data in order to make an accurate assessment of the risk. In this paper we briefly survey the existing neutron-production data sets that are applicable to the space radiation transport problem, and we point out how neutron production from protons is different than neutron production from heavy ions. We also make comparisons of one the heavy-ion data sets with Boltzmann-Uehling-Uhlenbeck (BUU) calculations.

  15. Production rates of neon xenon isotopes by energetic neutrons

    NASA Technical Reports Server (NTRS)

    Leich, D. A.; Borg, R. J.; Lanier, V. B.

    1986-01-01

    As a first step in an experimental program to study the behavior of noble gases produced in situ in minerals, a suite of minerals and pure chemicals were irradiated with 14.5 MeV neutrons at LLNL's Rotating Target Neutron Source (RTNS-II) and production rates for noble gases were determined. While neutron effects in meteorites and lunar samples are dominated by low-energy neutron capture, more energetic cosmic-ray secondary neutrons can provide significant depth-dependent contributions to production of cosmogenic nuclides through endothermic reactions such as (n,2n), (n,np), (n,d) and (n,alpha). Production rates for nuclides produced by cosmic-ray secondary neutrons are therefore useful in interpreting shielding histories from the relative abundances of cosmogenic nuclides. Absolute production cross sections were calculated from isotope dilution analyses of NaCl, Mg, CsCl, and Ba(NO3)2 samples, assuming purity, stoichiometry, and quantitative noble gas retention and extraction. Relative production cross sections determined from neon isotopic ratios in the mineral samples were also considered in evaluating the neon production cross sections. Results are presented.

  16. Enhancing Neutron Beam Production with a Convoluted Moderator

    SciTech Connect

    Iverson, Erik B; Baxter, David V; Muhrer, Guenter; Ansell, Stuart; Gallmeier, Franz X; Dalgliesh, Robert; Lu, Wei; Kaiser, Helmut

    2014-10-01

    We describe a new concept for a neutron moderating assembly resulting in the more efficient production of slow neutron beams. The Convoluted Moderator, a heterogeneous stack of interleaved moderating material and nearly transparent single-crystal spacers, is a directionally-enhanced neutron beam source, improving beam effectiveness over an angular range comparable to the range accepted by neutron beam lines and guides. We have demonstrated gains of 50% in slow neutron intensity for a given fast neutron production rate while simultaneously reducing the wavelength-dependent emission time dispersion by 25%, both coming from a geometric effect in which the neutron beam lines view a large surface area of moderating material in a relatively small volume. Additionally, we have confirmed a Bragg-enhancement effect arising from coherent scattering within the single-crystal spacers. We have not observed hypothesized refractive effects leading to additional gains at long wavelength. In addition to confirmation of the validity of the Convoluted Moderator concept, our measurements provide a series of benchmark experiments suitable for developing simulation and analysis techniques for practical optimization and eventual implementation at slow neutron source facilities.

  17. Laser ion acceleration and neutron source in short-pulse solid- nanoparticle interaction

    NASA Astrophysics Data System (ADS)

    Nishihara, K.; Watari, T.; Matsukado, K.; Sekine, T.; Takeuchi, Y.; Takagi, M.; Satoh, N.; Kawashima, T.; Kan, H.

    2016-03-01

    We propose both an efficient neutron source and an extremely high energy proton source using solid CD and CH nano-particles, respectively, irradiated by an intense laser light. With a use of 3-d PIC simulations, we obtain an optimum CD radius for a neutron source, 250 nm and required laser field of a=eE/mωc ≈ 2, which results in D-D reaction rate of <σv> = 2x10-16 cm3/s, corresponding to an effective deuteron temperature of 500 keV to 1MeV. Reduction of neutron yield by pre-expansion is discussed. In a range of a ≈100, laser radiation pressure surrounding the particles accelerates electrons in the forward direction. Protons following the electrons become directional high energy, for example, proton energy of 450 MeV is obtained within 130 fs in CH particle interaction with 700 nm in radius. More than 10% of total protons in CH-particles are accelerated forward. Proton energy continuously increases with time and with the increase of particle size and the direction is also collimated with time.

  18. Time dependent Monte Carlo calculations of the ORELA (Oak Ridge Electron Linear Accelerator) target neutron spectrum

    SciTech Connect

    Cramer, S.N.; Perey, F.G.

    1990-01-01

    The time dependent spectrum of neutrons in the water-moderated Oak Ridge Electron Linear Accelerator (ORELA) target has been calculated using a modified version of the MORSE multi-group Monte Carlo code with an analytic hydrogen scattering model. Distributions of effective neutron distance traversed in the target are estimated with a time and energy dependent algorithm from the leakage normal to the target face. These data are used in the resonance shaped analyses of time-of-flight cross section measurements to account for the experimental resolution function. The 20 MeV--10 eV energy range is adequately represented in the MORSE code by the 174 group VITAMIN-E cross section library with a P{sub 5} expansion. An approximate representation of the ORELA positron source facility, recently installed near the target, has been included in the calculations to determine any perturbations the positron source might create in the computed neutron distributions from the target. A series of coupled Monte Carlo calculations was performed from the target to the positron source and back to the target using a next-event estimation surface source for each step. The principal effect of the positron source was found to be an increase in the distance for the lower energy neutron spectra, producing no real change in the distributions where the ORELA source is utilized for experiments. Different configurations for the target were investigated in order to simulate the placement of a shadow bar in the neutron beam. These beam configurations included neutrons escaping from : (1) the central tantalum plates only, (2) the entire target with the tantalum plates blocked out, and (3) only a small area from the water. Comparisons of the current data with previous calculations having a less detailed model of the tantalum plates have been satisfactory. 10 refs.

  19. Neutronic and Physical Characteristics of an Accelerator Driven System with a Lead-208 Coolant

    SciTech Connect

    Khorasanov, Georgy L.; Ivonov, Anatoly P.; Blokhin, Anatoly I.

    2006-07-01

    In the paper a possibility of using a lead isotope, pure Pb-208, as a coolant for a subcritical core of 80 MW thermal capacity of the PDS-XADS type facility is considered. Calculations of neutronic characteristics were performed using Monte Carlo technique. The following initial data were chosen: an annular core with a target, as a neutron source, at its centre; the core coolant -- Pb-208 (100%); a fuel -- a mix of mono nitrides of depleted uranium and power plutonium with a small share of neptunium and americium; the target coolant -- a modified lead and bismuth eutectic, Pb-208(80%)-Bi(20%); proton beam energy -- 600 MeV; effective multiplication factor of the core under operation -- K{sub eff} = 0.97; thermal capacity of the core -- N = 80 MW. From calculations performed it follows that in using Pb-208 as the core coolant the necessary intensity of the external source of neutrons to deliver 80 MW thermal capacity is equal to S = 2.29-10{sup 17} n/s that corresponds to proton beam current I{sub p} = 2.8 mA and beam capacity P{sub p} 1.68 MW. In using natural lead instead of Pb-208 as the core coolant, effective multiplication factor of the core in normal operating regime falls down to the value equal to K{sub eff} = 0.95. In these conditions multiplication of external neutrons in the core and thermal capacity of the subcritical core are below nominal by 1.55 times. For achievement the rated core power N=80 MW it is required on {approx}20-30% to increase the fuel loading and volume of the core, or by 1.55 times to increase intensity of the external source of neutrons. In the last case, the required parameters of the neutron source and of the corresponding proton beam are following: intensity of the neutron source S = 3.55 10{sup 17} n/s., beam current I{sub p} = 4.32 mA, beam capacity P{sub p} 2.59 MW. To exploit the accelerator with the reduced proton beam current it will be required about 56 tons of Pb-208, as a minimum, for the core coolant. Charges for its

  20. A comparison of acceleration methods for solving the neutron transport k-eigenvalue problem

    SciTech Connect

    Willert, Jeffrey; Park, H.; Knoll, D.A.

    2014-10-01

    Over the past several years a number of papers have been written describing modern techniques for numerically computing the dominant eigenvalue of the neutron transport criticality problem. These methods fall into two distinct categories. The first category of methods rewrite the multi-group k-eigenvalue problem as a nonlinear system of equations and solve the resulting system using either a Jacobian-Free Newton–Krylov (JFNK) method or Nonlinear Krylov Acceleration (NKA), a variant of Anderson Acceleration. These methods are generally successful in significantly reducing the number of transport sweeps required to compute the dominant eigenvalue. The second category of methods utilize Moment-Based Acceleration (or High-Order/Low-Order (HOLO) Acceleration). These methods solve a sequence of modified diffusion eigenvalue problems whose solutions converge to the solution of the original transport eigenvalue problem. This second class of methods is, in our experience, always superior to the first, as most of the computational work is eliminated by the acceleration from the LO diffusion system. In this paper, we review each of these methods. Our computational results support our claim that the choice of which nonlinear solver to use, JFNK or NKA, should be secondary. The primary computational savings result from the implementation of a HOLO algorithm. We display computational results for a series of challenging multi-dimensional test problems.

  1. A comparison of acceleration methods for solving the neutron transport k-eigenvalue problem

    NASA Astrophysics Data System (ADS)

    Willert, Jeffrey; Park, H.; Knoll, D. A.

    2014-10-01

    Over the past several years a number of papers have been written describing modern techniques for numerically computing the dominant eigenvalue of the neutron transport criticality problem. These methods fall into two distinct categories. The first category of methods rewrite the multi-group k-eigenvalue problem as a nonlinear system of equations and solve the resulting system using either a Jacobian-Free Newton-Krylov (JFNK) method or Nonlinear Krylov Acceleration (NKA), a variant of Anderson Acceleration. These methods are generally successful in significantly reducing the number of transport sweeps required to compute the dominant eigenvalue. The second category of methods utilize Moment-Based Acceleration (or High-Order/Low-Order (HOLO) Acceleration). These methods solve a sequence of modified diffusion eigenvalue problems whose solutions converge to the solution of the original transport eigenvalue problem. This second class of methods is, in our experience, always superior to the first, as most of the computational work is eliminated by the acceleration from the LO diffusion system. In this paper, we review each of these methods. Our computational results support our claim that the choice of which nonlinear solver to use, JFNK or NKA, should be secondary. The primary computational savings result from the implementation of a HOLO algorithm. We display computational results for a series of challenging multi-dimensional test problems.

  2. Proposed second harmonic acceleration system for the intense pulsed neutron source rapid cycling synchrotron

    SciTech Connect

    Norem, J.; Brandeberry, F.; Rauchas, A.

    1983-01-01

    The Rapid Cycling Synchrotron (RCS) of the Intense Pulsed Neutron Source (IPNS) operating at Argonne National Laboratory is presently producing intensities of 2 to 2.5 x 10/sup 12/ protons per pulse (ppp) with the addition of a new ion source. This intensity is close to the space charge limit of the machine, estimated at approx.3 x 10/sup 12/ ppp, depending somewhat on the available aperture. With the present good performance in mind, accelerator improvements are being directed at: (1) increasing beam intensities for neutron science; (2) lowering acceleration losses to minimize activation; and (3) gaining better control of the beam so that losses can be made to occur when and where they can be most easily controlled. On the basis of preliminary measurements, we are now proposing a third cavity for the RF systems which would provide control of the longitudinal bunch shape during the cycle which would permit raising the effective space charge limit of the accelerator and reducing losses.

  3. Intense combined source of neutrons and photons for interrogation based on compact deuteron RF accelerator

    SciTech Connect

    Kurennoy, S. S.; Garnett, R. W.; Rybarcyk, L. J.

    2015-06-18

    Interrogation of special nuclear materials can benefit from mobile sources providing significant fluxes of neutrons (108/s at 2.5 MeV, 1010/s at 14.1 MeV) and of photons (>1012/s at 1-3 MeV). We propose a source that satisfies these requirements simultaneously plus also provides, via the reaction 11B(d,n)12C(γ15.1), a significant flux of 15-MeV photons, which are highly penetrating and optimal for inducing photo-fission in actinides. The source is based on a compact (< 5 m) deuteron RF accelerator that delivers an average current of a few mA of deuterons at 3-4 MeV to a boron target. The accelerator consists of a short RFQ followed by efficient inter-digital H-mode structures with permanent-magnet-quadrupole beam focusing [Kurennoy et al. (2012)], which suit perfectly for deuteron acceleration at low energies. Our estimates, based on recent measurements, indicate that the required fluxes of both neutrons and photons can be achieved at ~1 mA of 4-MeV deuterons. The goal of the proposed study is to confirm feasibility of the approach and develop requirements for future full system implementation.

  4. Intense combined source of neutrons and photons for interrogation based on compact deuteron RF accelerator

    DOE PAGESBeta

    Kurennoy, S. S.; Garnett, R. W.; Rybarcyk, L. J.

    2015-06-18

    Interrogation of special nuclear materials can benefit from mobile sources providing significant fluxes of neutrons (108/s at 2.5 MeV, 1010/s at 14.1 MeV) and of photons (>1012/s at 1-3 MeV). We propose a source that satisfies these requirements simultaneously plus also provides, via the reaction 11B(d,n)12C(γ15.1), a significant flux of 15-MeV photons, which are highly penetrating and optimal for inducing photo-fission in actinides. The source is based on a compact (< 5 m) deuteron RF accelerator that delivers an average current of a few mA of deuterons at 3-4 MeV to a boron target. The accelerator consists of a shortmore » RFQ followed by efficient inter-digital H-mode structures with permanent-magnet-quadrupole beam focusing [Kurennoy et al. (2012)], which suit perfectly for deuteron acceleration at low energies. Our estimates, based on recent measurements, indicate that the required fluxes of both neutrons and photons can be achieved at ~1 mA of 4-MeV deuterons. The goal of the proposed study is to confirm feasibility of the approach and develop requirements for future full system implementation.« less

  5. A comparison between a TESQ accelerator and a reactor as a neutron sources for BNCT

    NASA Astrophysics Data System (ADS)

    Burlon, A. A.; Kreiner, A. J.

    2008-03-01

    In this work, the performance of an accelerator-based neutron source design has been compared with that of a modern fluoride-filtered reactor-based epithermal beam having near-optimal quality for treatment of deep seated tumors in relation to its applicability for BNCT. The accelerator is a Tandem-Electrostatic-Quadrupole (TESQ) accelerator which is a design under development at the National Atomic Energy Commission (CNEA) in Buenos Aires, Argentina based on the 7Li(p,n)7Be reaction, relatively close to its energy threshold. The reactor is the Massachusetts Institute of Technology reactor upgraded with a Fission Converter Beam (MIT-FCB) and improved with an 8 mm thick 6Li filter. The comparison has been done by means of data reported on the MIT-FCB + 6Li filter performance and MCNP simulations on our TESQ design considering the neutron fluxes provided by the two sources and the doses delivered in a human phantom by both devices. The results show a deeper advantage depth (AD) for the TESQ which turns out to be a promising alternative to a reactor-based BNCT treatment.

  6. Converged accelerated finite difference scheme for the multigroup neutron diffusion equation

    SciTech Connect

    Terranova, N.; Mostacci, D.; Ganapol, B. D.

    2013-07-01

    Computer codes involving neutron transport theory for nuclear engineering applications always require verification to assess improvement. Generally, analytical and semi-analytical benchmarks are desirable, since they are capable of high precision solutions to provide accurate standards of comparison. However, these benchmarks often involve relatively simple problems, usually assuming a certain degree of abstract modeling. In the present work, we show how semi-analytical equivalent benchmarks can be numerically generated using convergence acceleration. Specifically, we investigate the error behavior of a 1D spatial finite difference scheme for the multigroup (MG) steady-state neutron diffusion equation in plane geometry. Since solutions depending on subsequent discretization can be envisioned as terms of an infinite sequence converging to the true solution, extrapolation methods can accelerate an iterative process to obtain the limit before numerical instability sets in. The obtained results have been compared to the analytical solution to the 1D multigroup diffusion equation when available, using FORTRAN as the computational language. Finally, a slowing down problem has been solved using a cascading source update, showing how a finite difference scheme performs for ultra-fine groups (104 groups) in a reasonable computational time using convergence acceleration. (authors)

  7. Neutronics analysis of three beam-filter assemblies for an accelerator-based BNCT facility

    SciTech Connect

    Bleuel, D.L.; Costes, S.V.; Donahue, R.J.; Ludewigt, B.A.

    1997-08-01

    Three moderator materials, AlF{sub 3}/Al, D{sub 2}O and LiF, have been analyzed for clinical usefulness using the reaction {sup 7}Li(p,n) as an accelerator driven neutron source. Proton energies between 2.1 MeV and 2.6 MeV have been investigated. Radiation transport in the reflector/moderator assembly is simulated using the MCNP program. Depth-dose distributions in a head phanton are calculated with the BNCT-RTPE patient treatment planning program from INEEL using the MCNP generated neutron and photon spectra as the subsequent source. Clinical efficacy is compared using the current BMRR protocol for all designs. Depth-dose distributions are compared for a fixed normal tissue tolerance dose of 12.5 Gy-Eq. Radiation analyses also include a complete anthropomorphic phantom. Results of organ and whole body dose components are presented for several designs. Results indicate that high quality accelerator beams may produce clinically favorable treatments to deep-seated tumors when compared to the BMRR beam. Also discussed are problems identified in comparing accelerator and reactor based designs using in-air figures of merit as well as some results of spectrum-averaged RBE`s.

  8. Production, distribution and applications of californium-252 neutron sources.

    PubMed

    Martin, R C; Knauer, J B; Balo, P A

    2000-01-01

    The radioisotope 252Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-yr half-life. A source the size of a person's little finger can emit up to 10(11) neutrons s(-1). Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement and minerals, as well as for detection and identification of explosives, land mines and unexploded military ordinance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 yr of experience and by US Bureau of Mines tests of source survivability during explosions. The production and distribution center for the US Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells 252Cf to commercial reencapsulators domestically and internationally. Sealed 252Cf sources are also available for loan to agencies and subcontractors of the US government and to universities for educational, research and medical applications. The REDC has established the Californium User Facility (CUF) for Neutron Science to make its large inventory of 252Cf sources available to researchers for irradiations inside uncontaminated hot cells. Experiments at the CUF include a land mine detection system, neutron damage testing of solid-state detectors, irradiation of human cancer cells for boron neutron capture therapy experiments and irradiation of rice to induce genetic mutations. PMID:11003521

  9. Magnetic Energy Production by Turbulence in Binary Neutron Star Mergers

    NASA Astrophysics Data System (ADS)

    Zrake, Jonathan; MacFadyen, Andrew I.

    2013-06-01

    The simultaneous detection of electromagnetic and gravitational wave emission from merging neutron star binaries would greatly aid in their discovery and interpretation. By studying turbulent amplification of magnetic fields in local high-resolution simulations of neutron star merger conditions, we demonstrate that magnetar-level (gsim 1016 G) fields are present throughout the merger duration. We find that the small-scale turbulent dynamo converts 60% of the randomized kinetic energy into magnetic fields on a merger timescale. Since turbulent magnetic energy dissipates through reconnection events that accelerate relativistic electrons, turbulence may facilitate the conversion of orbital kinetic energy into radiation. If 10-4 of the ~1053 erg of orbital kinetic available gets processed through reconnection and creates radiation in the 15-150 keV band, then the fluence at 200 Mpc would be 10-7 erg cm-2, potentially rendering most merging neutron stars in the advanced LIGO and Virgo detection volumes detectable by Swift BAT.

  10. Neutron source, linear-accelerator fuel enricher and regenerator and associated methods

    DOEpatents

    Steinberg, Meyer; Powell, James R.; Takahashi, Hiroshi; Grand, Pierre; Kouts, Herbert

    1982-01-01

    A device for producing fissile material inside of fabricated nuclear elements so that they can be used to produce power in nuclear power reactors. Fuel elements, for example, of a LWR are placed in pressure tubes in a vessel surrounding a liquid lead-bismuth flowing columnar target. A linear-accelerator proton beam enters the side of the vessel and impinges on the dispersed liquid lead-bismuth columns and produces neutrons which radiate through the surrounding pressure tube assembly or blanket containing the nuclear fuel elements. These neutrons are absorbed by the natural fertile uranium-238 elements and are transformed to fissile plutonium-239. The fertile fuel is thus enriched in fissile material to a concentration whereby they can be used in power reactors. After use in the power reactors, dispensed depleted fuel elements can be reinserted into the pressure tubes surrounding the target and the nuclear fuel regenerated for further burning in the power reactor.

  11. Neutron spectrometry of JET discharges with ICRH-acceleration of helium beam ions

    SciTech Connect

    Gatu Johnson, M.; Sunden, E. Andersson; Cecconello, M.; Conroy, S.; Ericsson, G.; Eriksson, J.; Hellesen, C.; Sangaroon, S.; Weiszflog, M.; Gorini, G.; Nocente, M.; Tardocchi, M.; Kiptily, V.; Sharapov, S. E. [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon; Euratom Eester, D. van [JET-EFDA, Culham Science Centre, OX14 3DB, Abingdon; LPP-ERM Collaboration: JET EFDA Contributors

    2010-10-15

    Recent experiments at JET aimed at producing {sup 4}He ions in the MeV range through third harmonic ion cyclotron resonance heating (ICRH) acceleration of {sup 4}He beams in a {sup 4}He dominated plasma. MeV range D was also present through parasitic ICRH absorption on residual D. In this contribution, we analyze TOFOR neutron spectrometer data from these experiments. A consistent description of the data is obtained with d(d,n){sup 3}He and {sup 9}Be({alpha},n){sup 12}C neutron components calculated using Stix distributions for the fast D and {sup 4}He, taking finite Larmor radius effects into account and with a ICRH power partition of P{sub D}{sup RF}=0.01xP{sub 4He}{sup RF}, in agreement with TOMCAT simulations.

  12. A Los Alamos concept for accelerator transmutation of waste and energy production (ATW)

    SciTech Connect

    Not Available

    1990-12-31

    This document contains the diagrams presented at the ATW (Accelerator Transmutation of Waste and Energy Production) External Review, December 10-12, 1990, held at Los Alamos National Laboratory. Included are the charge to the committee and the presentations for the committee`s review. Topics of the presentations included an overview of the concept, LINAC technology, near-term application -- high-level defense wastes (intense thermal neutron source, chemistry and materials), advanced application of the ATW concept -- fission energy without a high-level waste stream (overview, advanced technology, and advanced chemistry), and a summary of the research issues.

  13. Production and storage of ultra cold neutrons in superfluid helium

    SciTech Connect

    Greene, G.L.; Lamoreaux, S.

    1998-12-31

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL) concerning the investigation of a new method for the experimental exploitation of ultra-cold neutrons. The production and storage of ultra cold neutrons in superfluid helium has been suggested as a tool for the production of high densities of ultra cold neutrons for fundamental nuclear physics as well as for sensitive measurements for condensed matter. A particular application of this technique has been suggested by Doyle and Lamoreaux that involves the trapping of neutrons in a magnetic field within the superfluid helium volume. Neutron decays within the trap volume are detected by the scintillation light produced in the liquid helium. A cryostat and magnetic trap have been constructed as well as a prototype light detection system. This system was installed on a cold neutron beam line at the NIST Cold Neutron Research Facility in the summer of 1997. Preliminary results indicate the detection of helium scintillation light from the detection vessel.

  14. GPU-accelerated 3D neutron diffusion code based on finite difference method

    SciTech Connect

    Xu, Q.; Yu, G.; Wang, K.

    2012-07-01

    Finite difference method, as a traditional numerical solution to neutron diffusion equation, although considered simpler and more precise than the coarse mesh nodal methods, has a bottle neck to be widely applied caused by the huge memory and unendurable computation time it requires. In recent years, the concept of General-Purpose computation on GPUs has provided us with a powerful computational engine for scientific research. In this study, a GPU-Accelerated multi-group 3D neutron diffusion code based on finite difference method was developed. First, a clean-sheet neutron diffusion code (3DFD-CPU) was written in C++ on the CPU architecture, and later ported to GPUs under NVIDIA's CUDA platform (3DFD-GPU). The IAEA 3D PWR benchmark problem was calculated in the numerical test, where three different codes, including the original CPU-based sequential code, the HYPRE (High Performance Pre-conditioners)-based diffusion code and CITATION, were used as counterpoints to test the efficiency and accuracy of the GPU-based program. The results demonstrate both high efficiency and adequate accuracy of the GPU implementation for neutron diffusion equation. A speedup factor of about 46 times was obtained, using NVIDIA's Geforce GTX470 GPU card against a 2.50 GHz Intel Quad Q9300 CPU processor. Compared with the HYPRE-based code performing in parallel on an 8-core tower server, the speedup of about 2 still could be observed. More encouragingly, without any mathematical acceleration technology, the GPU implementation ran about 5 times faster than CITATION which was speeded up by using the SOR method and Chebyshev extrapolation technique. (authors)

  15. Leading neutron production at HERA in the color dipole approach

    NASA Astrophysics Data System (ADS)

    Carvalho, F.; Gonçalves, V. P.; Spiering, D.; Navarra, F. S.

    2016-03-01

    In this work we study leading neutron production in e + p → e + n + X collisions at high energies and calculate the Feynman xL distribution of these neutrons. The differential cross section is written in terms of the pion flux and of the photon-pion total cross section. We describe this process using the color dipole formalism and, assuming the validity of the additive quark model, we relate the dipole-pion with the well determined dipoleproton cross section. In this formalism we can estimate the impact of the QCD dynamics at high energies as well as the contribution of gluon saturation effects to leading neutron production. With the parameters constrained by other phenomenological information, we are able to reproduce the basic features of the recently released H1 leading neutron spectra.

  16. Neutron spectra due (13)N production in a PET cyclotron.

    PubMed

    Benavente, J A; Vega-Carrillo, H R; Lacerda, M A S; Fonseca, T C F; Faria, F P; da Silva, T A

    2015-05-01

    Monte Carlo and experimental methods have been used to characterize the neutron radiation field around PET (Positron Emission Tomography) cyclotrons. In this work, the Monte Carlo code MCNPX was used to estimate the neutron spectra, the neutron fluence rates and the ambient dose equivalent (H*(10)) in seven locations around a PET cyclotron during (13)N production. In order to validate these calculations, H*(10) was measured in three sites and were compared with the calculated doses. All the spectra have two peaks, one above 0.1MeV due to the evaporation neutrons and another in the thermal region due to the room-return effects. Despite the relatively large difference between the measured and calculated H*(10) for one point, the agreement was considered good, compared with that obtained for (18)F production in a previous work. PMID:25699664

  17. Neutron production by 200 mJ ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Pretzler, G.; Saemann, A.; Pukhov, A.; Rudolph, D.; Schätz, T.; Schramm, U.; Thirolf, P.; Habs, D.; Eidmann, K.; Tsakiris, G. D.; Meyer-Ter-Vehn, J.; Witte, K. J.

    1998-07-01

    We report the observation of neutrons released from d(d,n)3He fusion reactions in the focus of 200 mJ, 160 fs Ti:sapphire laser pulses on a deuterated polyethylene target. Optimizing the fast electron and ion generation by applying a well-defined prepulse led to an average rate of 140 neutrons per shot. Furthermore, the production of a substantial number of MeV γ rays could be observed. The occurrence of neutrons and γ rays is attributed to the formation and explosion of a relativistic plasma channel in the laser focus, which is confirmed by numerical calculations.

  18. Small Reactor for Semiconductor Production by Neutron Transmutation Doping

    SciTech Connect

    Obara, Toru; Hong, Liem Peng

    2010-06-22

    New concept of small size nuclear reactor is proposed for Neutron Transmutation Doping (NTD). The reactor core consists of conventional PWR type fuel elements with light water moderator/coolant unlike conventional research reactors. Graphite reflector is employed for large neutron irradiation volume. Silicon ingots are put into the reflector region for irradiation. Neutronic analysis results show that this concept has possibility to product large amount of silicon ingots which have large diameter. An optimal reactor design and its performance are shown as a result of analysis in the paper.

  19. Transient particle acceleration in strongly magnetized neutron stars. II - Effects due to a dipole field geometry

    NASA Technical Reports Server (NTRS)

    Fatuzzo, Marco; Melia, Fulvio

    1991-01-01

    Sheared Alfven waves generated by nonradial crustal disturbances above the polar cap of a strongly magnetized neutron star induce an electric field component parallel to B. An attempt is made to determine the manner in which the strong radial dependence of B affects the propagation of these sheared Alfven waves, and whether this MHD process is still an effective particle accelerator. It is found that although the general field equation is quite complicated, a simple wavelike solution can still be obtained under the conditions of interest for which the Alfven phase velocity decouples from the wave equation. The results may be applicable to gamma-ray burst sources.

  20. Test simulation of neutron damage to electronic components using accelerator facilities

    NASA Astrophysics Data System (ADS)

    King, D. B.; Fleming, R. M.; Bielejec, E. S.; McDonald, J. K.; Vizkelethy, G.

    2015-12-01

    The purpose of this work is to demonstrate equivalent bipolar transistor damage response to neutrons and silicon ions. We report on irradiation tests performed at the White Sands Missile Range Fast Burst Reactor, the Sandia National Laboratories (SNL) Annular Core Research Reactor, the SNL SPHINX accelerator, and the SNL Ion Beam Laboratory using commercial silicon npn bipolar junction transistors (BJTs) and III-V Npn heterojunction bipolar transistors (HBTs). Late time and early time gain metrics as well as defect spectra measurements are reported.

  1. Radiation dose measurements and Monte Carlo calculations for neutron and photon reactions in a human head phantom for accelerator-based boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Kim, Don-Soo

    Dose measurements and radiation transport calculations were investigated for the interactions within the human brain of fast neutrons, slow neutrons, thermal neutrons, and photons associated with accelerator-based boron neutron capture therapy (ABNCT). To estimate the overall dose to the human brain, it is necessary to distinguish the doses from the different radiation sources. Using organic scintillators, human head phantom and detector assemblies were designed, constructed, and tested to determine the most appropriate dose estimation system to discriminate dose due to the different radiation sources that will ultimately be incorporated into a human head phantom to be used for dose measurements in ABNCT. Monoenergetic and continuous energy neutrons were generated via the 7Li(p,n)7Be reaction in a metallic lithium target near the reaction threshold using the 5.5 MV Van de Graaff accelerator at the University of Massachusetts Lowell. A human head phantom was built to measure and to distinguish the doses which result from proton recoils induced by fast neutrons, alpha particles and recoil lithium nuclei from the 10B(n,alpha)7Li reaction, and photons generated in the 7Li accelerator target as well as those generated inside the head phantom through various nuclear reactions at the same time during neutron irradiation procedures. The phantom consists of two main parts to estimate dose to tumor and dose to healthy tissue as well: a 3.22 cm3 boron loaded plastic scintillator which simulates a boron containing tumor inside the brain and a 2664 cm3 cylindrical liquid scintillator which represents the surrounding healthy tissue in the head. The Monte Carlo code MCNPX(TM) was used for the simulation of radiation transport due to neutrons and photons and extended to investigate the effects of neutrons and other radiation on the brain at various depths.

  2. Brighter H/sup -/ source for the intense pulsed neutron source accelerator system

    SciTech Connect

    Stipp, V.; DeWitt, A.; Madsen, J.

    1983-01-01

    Further increases in the beam intensity of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory required the replacement of the H/sup -/ source with a higher current source. A magnetron ion source of Fermi National Accelerator Laboratory (FNAL) design was adapted with a grooved cathode to provide a stable 40 to 50 mA of beam operating at 30 Hz for up to a 90 ..mu..s pulse duration. Problems of space charge blowup due to the lack of neutralization of the H/sup -/ beam were solved by injecting additional gs into the 20 keV transport system. The source has recently been installed in the machine and the available input to the accelerator has more than doubled.

  3. Production, Distribution, and Applications of Californium-252 Neutron Sources

    SciTech Connect

    Balo, P.A.; Knauer, J.B.; Martin, R.C.

    1999-10-03

    The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6-year half-life. A source the size of a person's little finger can emit up to 10{sup 11} neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). DOE sells The radioisotope {sup 252}Cf is routinely encapsulated into compact, portable, intense neutron sources with a 2.6- year half-life. A source the size of a person's little finger can emit up to 10 neutrons/s. Californium-252 is used commercially as a reliable, cost-effective neutron source for prompt gamma neutron activation analysis (PGNAA) of coal, cement, and minerals, as well as for detection and identification of explosives, laud mines, and unexploded military ordnance. Other uses are neutron radiography, nuclear waste assays, reactor start-up sources, calibration standards, and cancer therapy. The inherent safety of source encapsulations is demonstrated by 30 years of experience and by U.S. Bureau of Mines tests of source survivability during explosions. The production and distribution center for the U. S Department of Energy (DOE) Californium Program is the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory(ORNL). DOE sells {sup 252}Cf to commercial

  4. Optimum design and criticality safety of a beam-shaping assembly with an accelerator-driven subcritical neutron multiplier for boron neutron capture therapies.

    PubMed

    Hiraga, F

    2015-12-01

    The beam-shaping assembly for boron neutron capture therapies with a compact accelerator-driven subcritical neutron multiplier was designed so that an epithermal neutron flux of 1.9×10(9) cm(-2) s(-1) at the treatment position was generated by 5 MeV protons in a beam current of 2 mA. Changes in the atomic density of (135)Xe in the nuclear fuel due to the operation of the beam-shaping assembly were estimated. The criticality safety of the beam-shaping assembly in terms of Xe poisoning is discussed. PMID:26235186

  5. Neutron-induced gamma-ray production

    SciTech Connect

    Nelson, R.O.; Drake, D.M.; Haight, R.C.; Laymon, C.M.; Wender, S.A.; Young, P.G. ); Drosg, M.; Pavlik, A.; Vonach, H. . Inst. fuer Radiumforschung und Kernphysik); Larson, D.C. )

    1990-01-01

    High resolution Ge detectors coupled with the WNR high-intensity, high-energy, pulsed neutron source at LAMPF recently have been used to measure a variety of reactions including (n,xn) for 1 {le} x {le} 11, (n,n{alpha}), (n,np), etc. The reactions are identified by the known gamma-ray energies of prompt transitions between the low lying states in the final nuclei. With our spallation neutron source cross section data are obtained at all neutron energies from a few MeV to over 200 MeV. Applications of the data range from assisting the interpretation of the planned Mars Observer mission to map the elemental composition of the martian surface, to providing data for nuclear model verification and understanding reaction mechanisms. For example, a study of the Pb(n,xn) reactions for 2 {le} x {le} 11 populating the first excited states of the even Pb isotopes is underway. These data will be used to test preequilibrium and other reaction models. 9 refs., 5 figs.

  6. Production of Medical isotope Technecium-99 from DT Fusion neutrons

    NASA Astrophysics Data System (ADS)

    Boguski, John; Gentile, Charles; Ascione, George

    2011-10-01

    High energy neutrons produced in DT fusion reactors have a secondary application for use in the synthesis of valuable man-made isotopes utilized in industry today. One such isotope is metastable Technecium-99 (Tc99m), a low energy gamma emitter used in ~ 85% of all medical imaging diagnostics. Tc99m is created through beta decay of Molybdenum-99 (Mo99), which itself has only a 66 hour half-life and must be created from a neutron capture by the widely available and stable isotope Molydenum-98. Current worldwide production of Tc99m occurs in just five locations and relies on obtaining the fission byproduct Mo99 from highly enriched Uranium reactors. A Tc99m generator using DT fusion neutrons, however, could potentially be operated at individual hospitals and medical facilities without the use of any fissile material. The neutron interaction of the DT neutrons with Molybdenum in a potential device geometry was modeled using Monte Carlo neutron transport code MCNP. Trial experiments were also performed to test the viability of using DT neutrons to create ample quantities of Tc99m. Modeling and test results will follow.

  7. Exploration of Adiabatic Resonance Crossing Through Neutron Activator Design for Thermal and Epithermal Neutron Formation in (99)Mo Production and BNCT Applications.

    PubMed

    Khorshidi, Abdollah

    2015-10-01

    A feasibility study was performed to design thermal and epithermal neutron sources for radioisotope production and boron neutron capture therapy (BNCT) by moderating fast neutrons. The neutrons were emitted from the reaction between (9)Be, (181)Ta, and (184)W targets and 30 MeV protons accelerated by a small cyclotron at 300 μA. In this study, the adiabatic resonance crossing (ARC) method was investigated by means of (207)Pb and (208)Pb moderators, graphite reflector, and boron absorber around the moderator region. Thermal/epithermal flux, energy, and cross section of accumulated neutrons in the activator were examined through diverse thicknesses of the specified regions. Simulation results revealed that the (181)Ta target had the highest neutron yield, and also tungsten was found to have the highest values in both surface and volumetric flux ratio. Transmutation in the (98)Mo sample through radiative capture was investigated for the natural lead moderator. When the sample radial distance from the target was increased inside the graphite region, the production yield had the greatest value of activity. The potential of the ARC method is a replacement or complements the current reactor-based supply sources of BNCT purposes. PMID:26397967

  8. MANTRA: Measuring Neutron Capture Cross Sections in Actinides with Accelerator Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Bauder, W.; Pardo, R. C.; Collon, P.; Palchan, T.; Scott, R.; Vondrasek, R.; Nusair, O.; Nair, C.; Paul, M.; Kondev, F.; Chen, J.; Youinou, G.; Salvatores, M.; Palmotti, G.; Berg, J.; Maddock, T.; Imel, G.

    2013-10-01

    With rising global energy needs, there is substantial interest in nuclear energy research. To explore possibilities for advanced fuel cycles, better neutron cross section data are needed for the minor actinides. The MANTRA (Measurement of Actinide Neutron TRAsmutation) project will improve these data by measuring integral (n, γ) cross sections. The cross sections will be extracted by measuring isotopic ratios in pure actinide samples, irradiated in the Advanced Test Reactor at Idaho National Lab, using Accelerator Mass Spectrometry(AMS) at the Argonne Tandem Linac Accelerator System (ATLAS). MANTRA presents a unique AMS challenge because of the goal to measure multiple isotopic ratios on a large number of samples. To meet these challenges, we have modified the AMS setup at ATLAS to include a laser ablation system for solid material injection into our ECR ion source. I will present work on the laser ablation system and modified source geometry, as well as preliminary measurements of unirradiated actinide samples at ATLAS. This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

  9. High Energy Neutron Induced Gamma Production

    SciTech Connect

    Brown, D A; Johnson, M; Navratil, P

    2007-09-28

    N Division has an interest in improving the physics and accuracy of the gamma data it provides to its customers. It was asked to look into major gamma producing reactions for 14 MeV incident neutrons for several low-Z materials and determine whether LLNL's processed data files faithfully represent the current state of experimental and theoretical knowledge for these reactions. To address this, we surveyed the evaluations of the requested materials, made recommendations for the next ENDL release and noted isotopes that will require further experimental study. This process uncovered several major problems in our translation and processing of the ENDF formatted evaluations, most of which have been resolved.

  10. Acceleration of solid particles by gaseous detonation products

    SciTech Connect

    Gavrilenko, T.P.; Grigoriev, V.V.; Zhdan, S.A.; Nikolaev, Y.A.; Boiko, V.M.; Papyrin, A.N.

    1986-11-01

    This investigation is concerned with a theoretical and experimental study of acceleration dynamics of spherically inert solid particles (100 ..mu..m nominal diameter) in flows of gaseous detonation products. The experiments were conducted in a detonation channel 1.5 m long with a 20 x 20 mm/sup 2/ cross section and one open end. Particle motion was observed with the method of multiexposure photographic recording and a laser stroboscopic light source. The character of velocity variation of individual particles inside and outside of the channel was investigated for different initial positions of particles. Under certain conditions the accelerated particles are destroyed. A mathematical model based on two-phase multivelocity continuum mechanics has been formulated to describe the detonation wave propagation, outflow of detonation products from the channel, and interaction between particles and a nonstationary flow of detonation products. The model includes chemical equilibrium of detonation products, particle acceleration, heat exchange between phases and channel walls, particle melting, and fragmentation of droplets if the Weber number exceeds some critical value. Particle destruction has been correlated with the initial position, diameter, and physical properties of particles. Comparison of computer and experimental results shows that the model satisfactorily describes acceleration, heating, and fragmentation of particles.

  11. Accelerating Data Acquisition, Reduction, and Analysis at the Spallation Neutron Source

    SciTech Connect

    Campbell, Stuart I; Kohl, James Arthur; Granroth, Garrett E; Miller, Ross G; Doucet, Mathieu; Stansberry, Dale V; Proffen, Thomas E; Taylor, Russell J; Dillow, David

    2014-01-01

    ORNL operates the world's brightest neutron source, the Spallation Neutron Source (SNS). Funded by the US DOE Office of Basic Energy Science, this national user facility hosts hundreds of scientists from around the world, providing a platform to enable break-through research in materials science, sustainable energy, and basic science. While the SNS provides scientists with advanced experimental instruments, the deluge of data generated from these instruments represents both a big data challenge and a big data opportunity. For example, instruments at the SNS can now generate multiple millions of neutron events per second providing unprecedented experiment fidelity but leaving the user with a dataset that cannot be processed and analyzed in a timely fashion using legacy techniques. To address this big data challenge, ORNL has developed a near real-time streaming data reduction and analysis infrastructure. The Accelerating Data Acquisition, Reduction, and Analysis (ADARA) system provides a live streaming data infrastructure based on a high-performance publish subscribe system, in situ data reduction, visualization, and analysis tools, and integration with a high-performance computing and data storage infrastructure. ADARA allows users of the SNS instruments to analyze their experiment as it is run and make changes to the experiment in real-time and visualize the results of these changes. In this paper we describe ADARA, provide a high-level architectural overview of the system, and present a set of use-cases and real-world demonstrations of the technology.

  12. (International Panel on 14 MeV Intense Neutron Source Based on Accelerators for Fusion Materials Study)

    SciTech Connect

    Thoms, K.R.; Wiffen, F.W.

    1991-02-14

    Both travelers were members of a nine-person US delegation that participated in an international workshop on accelerator-based 14 MeV neutron sources for fusion materials research hosted by the University of Tokyo. Presentations made at the workshop reviewed the technology developed by the FMIT Project, advances in accelerator technology, and proposed concepts for neutron sources. One traveler then participated in the initial meeting of the IEA Working Group on High Energy, High Flux Neutron Sources in which efforts were begun to evaluate and compare proposed neutron sources; the Fourth FFTF/MOTA Experimenters' Workshop which covered planning and coordination of the US-Japan collaboration using the FFTF reactor to irradiate fusion reactor materials; and held discussions with several JAERI personnel on the US-Japan collaboration on fusion reactor materials.

  13. Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

    NASA Astrophysics Data System (ADS)

    Burlon, Alejandro A.; Girola, Santiago; Valda, Alejandro A.; Minsky, Daniel M.; Kreiner, Andrés J.

    2010-08-01

    In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the 7Li(p, n)7Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

  14. Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

    SciTech Connect

    Burlon, Alejandro A.; Valda, Alejandro A.; Girola, Santiago; Minsky, Daniel M.; Kreiner, Andres J.

    2010-08-04

    In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the {sup 7}Li(p, n){sup 7}Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

  15. High power linear accelerators for tritium production and transmutation of nuclear waste

    SciTech Connect

    Lawrence, G.P.

    1990-01-01

    Proton linacs driving high-flux spallation neutron sources are being considered for transmutation of nuclear waste and production of tritium. Advances in high-current linac technology have provided a basis for the development of credible designs for the required accelerator, which has a nominal 1.6-GeV energy, and a 250-mA cw current. A beam with these parameters incident on a liquid lead-bismuth (Pb-Bi) target can generate a thermal neutron flux of up to 5 {times} 10{sup 16} n/cm{sup 2}-s in a cylindrical blanket surrounding the spallation source. This high flux can produce tritium through the {sup 6}Li(n,{alpha})T or {sup 3}He(n,{gamma})T reactions, or can burn long-lived actinides and fission products from nuclear waste through capture and fission processes. In some system scenarios, waste actinides and/or other fissile materials in the blanket can produce sufficient fission energy to power the accelerator.

  16. Preliminary energy-filtering neutron imaging with time-of-flight method on PKUNIFTY: A compact accelerator based neutron imaging facility at Peking University

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Zou, Yubin; Wen, Weiwei; Lu, Yuanrong; Guo, Zhiyu

    2016-07-01

    Peking University Neutron Imaging Facility (PKUNIFTY) works on an accelerator-based neutron source with a repetition period of 10 ms and pulse duration of 0.4 ms, which has a rather low Cd ratio. To improve the effective Cd ratio and thus improve the detection capability of the facility, energy-filtering neutron imaging was realized with the intensified CCD camera and time-of-flight (TOF) method. Time structure of the pulsed neutron source was firstly simulated with Geant4, and the simulation result was evaluated with experiment. Both simulation and experiment results indicated that fast neutrons and epithermal neutrons were concentrated in the first 0.8 ms of each pulse period; meanwhile in the period of 0.8-2.0 ms only thermal neutrons existed. Based on this result, neutron images with and without energy filtering were acquired respectively, and it showed that detection capability of PKUNIFTY was improved with setting the exposure interval as 0.8-2.0 ms, especially for materials with strong moderating capability.

  17. Low-dose neutron dose response of zebrafish embryos obtained from the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility

    NASA Astrophysics Data System (ADS)

    Ng, C. Y. P.; Kong, E. Y.; Konishi, T.; Kobayashi, A.; Suya, N.; Cheng, S. H.; Yu, K. N.

    2015-09-01

    The dose response of embryos of the zebrafish, Danio rerio, irradiated at 5 h post fertilization (hpf) by 2-MeV neutrons with ≤100 mGy was determined. The neutron irradiations were made at the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility in the National Institute of Radiological Sciences (NIRS), Chiba, Japan. A total of 10 neutron doses ranging from 0.6 to 100 mGy were employed (with a gamma-ray contribution of 14% to the total dose), and the biological effects were studied through quantification of apoptosis at 25 hpf. The responses for neutron doses of 10, 20, 25, and 50 mGy approximately fitted on a straight line, while those for neutron doses of 0.6, 1 and 2.5 mGy exhibited neutron hormetic effects. As such, hormetic responses were generically developed by different kinds of ionizing radiations with different linear energy transfer (LET) values. The responses for neutron doses of 70 and 100 mGy were significantly below the lower 95% confidence band of the best-fit line, which strongly suggested the presence of gamma-ray hormesis.

  18. Feasibility study of an intense pulsed neutron source based on a powerful electron accelerator and a pulsed nuclear reactor

    SciTech Connect

    Bosamykin, V.S.; Voinov, M.A.; Gordeev, V.S.; Kuvshinov, M.I.; Morunov, K.A.; Pavlovskii, A.I.; Selemir, V.D.

    1995-12-31

    A promising candidate for a highly intense neutron source is a system coupling a powerful pulsed electron accelerator and a pulsed fast-neutron nuclear reactor. The LIU-10-GIR complex, located at the All-Russian Institute of Experimental Physics (VNIIEF), is described. Experiments were carried out during 1984--1990 to study the joint operation of these two widely differing physical systems and resolve basic scientific research problems. Experimental results are given, and the potential use of such a system as an intense neutron source is suggested.

  19. Study of proton acceleration at the target front surface in laser-solid interactions by neutron spectroscopy

    SciTech Connect

    Youssef, A.; Kodama, R.; Tampo, M.

    2006-03-15

    Proton acceleration inside solid LiF and CH-LiF targets irradiated by a 450-fs, 20-J, 1053-nm laser at an intensity of 3x10{sup 18} W/cm{sup 2} has been studied via neutron spectroscopy. Neutron spectra produced through the {sup 7}Li(p,n){sup 7}Be reaction that occurs between accelerated protons, at the front surface, and background {sup 7}Li ions inside the target. From measured and calculated spectra, by three-dimensional Monte Carlo code, the maximum energy, total number, and slope temperature of the accelerated protons are investigated. The study indicates that protons originate at the front surface and are accelerated to a maximum energy that is reasonably consistent with the calculated one due to the ponderomotive force.

  20. Neutron spectra around a tandem linear accelerator in the generation of (18)F with a bonner sphere spectrometer.

    PubMed

    Lagares, J I; Araque, J E Guerrero; Méndez-Villafañe, R; Arce, P; Sansaloni, F; Vela, O; Díaz, C; Campo, Xandra; Pérez, J M

    2016-08-01

    A Bonner sphere spectrometer was used to measure the neutron spectra produced at the collision of protons with an H2(18)O target at different angles. A unique H2(18)O target to produce (18)F was designed and placed in a Tandem linear particle accelerator which produces 8.5MeV protons. The neutron count rates measured with the Bonner spheres were unfolded with the MAXED code. With the GEANT4 Monte Carlo code the neutron spectrum induced in the (p, n) reaction was estimated, this spectrum was used as initial guess during unfolding. Although the cross section of the reaction (18)O(p,n)(18)F is well known, the neutron energy spectra is not correctly defined and it is necessary to verify the simulation with measurements. For this reason, the sensitivity of the unfolding method to the initial spectrum was analyzed applying small variation to the fast neutron peak. PMID:27235889

  1. Effect of external shielding for neutrons during radiotherapy for prostate cancer, considering the 2300 CD linear accelerator and voxel phantom

    NASA Astrophysics Data System (ADS)

    Thalhofer, J. L.; Roque, H. S.; Rebello, W. F.; Correa, S. A.; Silva, A. X.; Souza, E. M.; Batita, D. V. S.; Sandrini, E. S.

    2014-02-01

    Photoneutron production occurs when high energy photons, greater than 6.7 MeV, interact with linear accelerator head structures. In Brazil, the National Cancer Institute, one of the centers of reference in cancer treatment, uses radiation at 4 angles (0°, 90°, 180° and 270°) as treatment protocol for prostate cancer. With the objective of minimizing the dose deposited in the patient due to photoneutrons, this study simulated radiotherapy treatment using MCNPX, considering the most realistic environment; simulating the radiotherapy room, the Linac 2300 head, the MAX phantom and the treatment protocol with the accelerator operating at 18 MV. In an attempt to reduce the dose deposited by photoneutrons, an external shielding was added to the Linac 2300. Results show that the equivalent dose due to photoneutrons deposited in the patient diminished. The biggest reduction was seen in bone structures, such as the tibia and fibula, and mandible, at approximately 75%. Besides that, organs such as the brain, pancreas, small intestine, lungs and thyroid revealed a reduction of approximately 60%. It can be concluded that the shielding developed by our research group is efficient in neutron shielding, reducing the dose for the patient, and thus, the risk of secondary cancer, and increasing patient survival rates.

  2. A study of the structural activation caused by proton beam loss in the {open_quotes}accelerator production of tritium{close_quotes} LINAC

    SciTech Connect

    Daemen, L.L.; Beard, C.A.; Eaton, S.L.; Waters, L.S.; Wilson, W.B.

    1997-01-01

    The Accelerator Production of Tritium (APT) project at Los Alamos National Laboratory makes use of a high power linear proton accelerator to produce neutrons via spallation reactions m a heavy metal target. The fast spallation neutrons are moderated by a heavy water blanket, and used to produce tritium by means of the reaction: {sup 3}He(n,p)T, APT 1993. Various accelerator designs are currently under consideration. At the time when this study was performed, the project called for a 1 GeV proton linear accelerator with a beam current of 200 mA, i.e., a proton beam power of 200 MW. Given the high power at which the APT accelerator is expected to operate, as well as the heavy maintenance that is likely to be required to keep it operating, it is essential to consider health physics issues at an early stage of the design.

  3. High-energy particle production in solar flares (SEP, gamma-ray and neutron emissions). [solar energetic particles

    NASA Technical Reports Server (NTRS)

    Chupp, E. L.

    1987-01-01

    Electrons and ions, over a wide range of energies, are produced in association with solar flares. Solar energetic particles (SEPs), observed in space and near earth, consist of electrons and ions that range in energy from 10 keV to about 100 MeV and from 1 MeV to 20 GeV, respectively. SEPs are directly recorded by charged particle detectors, while X-ray, gamma-ray, and neutron detectors indicate the properties of the accelerated particles (electrons and ions) which have interacted in the solar atmosphere. A major problem of solar physics is to understand the relationship between these two groups of charged particles; in particular whether they are accelerated by the same mechanism. The paper reviews the physics of gamma-rays and neutron production in the solar atmosphere and the method by which properties of the primary charged particles produced in the solar flare can be deduced. Recent observations of energetic photons and neutrons in space and at the earth are used to present a current picture of the properties of impulsively flare accelerated electrons and ions. Some important properties discussed are time scale of production, composition, energy spectra, accelerator geometry. Particular attention is given to energetic particle production in the large flare on June 3, 1982.

  4. Technology benefits resulting from accelerator production of tritium

    SciTech Connect

    1998-12-31

    One of the early and most dramatic uses of nuclear transformations was in development of the nuclear weapons that brought World War II to an end. Despite that difficult introduction, nuclear weapons technology has been used largely as a deterrent to war throughout the latter half of the twentieth century. The Accelerator Production of Tritium (APT) offers a clean, safe, and reliable means of producing the tritium (a heavy form of hydrogen) needed to maintain the nuclear deterrent. Tritium decays away naturally at a rate of about 5.5% per year; therefore, the tritium reservoirs in nuclear weapons must be periodically replenished. In recent years this has been accomplished by recycling tritium from weapons being retired from the stockpile. Although this strategy has served well since the last US tritium production reactor was shut down in 1988, a new tritium production capability will be required within ten years. Some benefits will result from direct utilization of some of the APT proton beam; others could result from advances in the technologies of particle accelerators and high power spallation targets. The APT may save thousands of lives through the production of medical isotopes, and it may contribute to solving the nation`s problem in disposing of long-lived nuclear wastes. But the most significant benefit may come from advancing the technology, so that the great potential of accelerator applications can be realized during our lifetimes.

  5. Determination of cross sections for the 238U(n,3n)236U reaction induced by 14-MeV neutrons with accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Wang, Xianggao; Jiang, Shan; He, Ming; Dong, Kejun; Xiao, Caijing; Hu, Yueming; You, Qubo; Chen, Hongtao; Hou, Long; Yu, WeiXiang; Ruan, Xichao

    2013-01-01

    The cross sections of the 238U(n,3n)236U reaction induced by neutrons with energies around 14 MeV were determined using a combination of the activation technique and accelerator mass spectrometry (AMS) at the China Institute of Atomic Energy (CIAE). U3O8 samples were irradiated for 198 h by neutrons produced by the 3H(d,n)4He reaction on a 600-kV neutron generator at CIAE. Neutron flux was continuously determined by the activation of flux monitors, Co foils, closely attached to the sample. To accurately determine the long half-life product 236U, an AMS procedure was established with a sensitivity of about 10-11 for 236U/238U. As a result, the cross sections of 238U(n,3n)236U for the incident neutron energies of (14.18±0.30) and (14.65±0.40) MeV were obtained to be (489.3±48.0) and (556.7±27.8) mb, respectively.

  6. ACCELERATOR SYSTEMS MODIFICATIONS FOR A SECOND TARGET STATION AT THE OAK RIDGE SPALLATION NEUTRON SOURCE

    SciTech Connect

    Galambos, John D; Kim, Sang-Ho; Plum, Michael A

    2014-01-01

    A second target station is planned for the Oak Ridge Spallation Neutron Source. The ion source will be upgraded to increase the peak current from 38 to 49 mA, additional superconducting RF cavities will be added to the linac to increase the H beam energy from 938 to 1300 MeV, and the accumulator ring will receive modifications to the injection and extraction systems to accommodate the higher beam energy. After pulse compression in the storage ring one sixth of the beam pulses (10 out of 60 Hz) will be diverted to the second target by kicker and septum magnets added to the existing Ring to Target Beam Transport (RTBT) line. No further modifications will be made to the RTBT so that when the kicker and septum magnets are turned off the original beam transport lattice will be unaffected. In this paper we will discuss these and other planned modifications and upgrades to the accelerator facility.

  7. Accelerated carbonation of cement pastes in situ monitored by neutron diffraction

    SciTech Connect

    Castellote, M. Andrade, C.; Turrillas, X.; Campo, J.; Cuello, G.J.

    2008-12-15

    In-situ monitoring of the changes that take place in the phase composition of cement pastes during accelerated carbonation (100% CO{sub 2}) for different binders, has been carried out, by taking Neutron Diffraction patterns in parallel with the carbonation experiments. The variation of the intensity of chosen reflections for each phase along the experiment has been used to monitor concentration changes and has supplied data, in real time, for fractional conversion of different phases (Portlandite, Ettringite and CSH gel) of the hydrated cement pastes. Fitting of these results has allowed to make a qualitative approach to the kinetics of the carbonation of the different phases and extracting conclusions on the microstructural changes that takes place during the carbonation of cement pastes.

  8. A parametric model to describe neutron spectra around high-energy electron accelerators and its application in neutron spectrometry with Bonner Spheres

    NASA Astrophysics Data System (ADS)

    Bedogni, Roberto; Pelliccioni, Maurizio; Esposito, Adolfo

    2010-03-01

    Due to the increased interest of the scientific community in the applications of synchrotron light, there is an increasing demand of high-energy electron facilities, testified by the construction of several new facilities worldwide. The radiation protection around such facilities requires accurate experimental methods to determine the dose due to prompt radiation fields. Neutron fields, in particular, are the most complex to measure, because they extend in energy from thermal (10 -8 MeV) up to hundreds MeV and because the responses of dosemeters and survey meters usually have large energy dependence. The Bonner Spheres Spectrometer (BSS) is in practice the only instrument able to respond over the whole energy range of interest, and for this reason it is frequently used to derive neutron spectra and dosimetric quantities in accelerator workplaces. Nevertheless, complex unfolding algorithms are needed to derive the neutron spectra from the experimental BSS data. This paper presents a parametric model specially developed for the unfolding of the experimental data measured with BSS around high-energy electron accelerators. The work consists of the following stages: (1) Generation with the FLUKA code, of a set of neutron spectra representing the radiation environment around accelerators with different electron energies; (2) formulation of a parametric model able to describe these spectra, with particular attention to the high-energy component (>10 MeV), which may be responsible for a large part of the dose in workplaces; and (3) implementation of this model in an existing unfolding code.

  9. Chronic acceleration and egg production in domestic fowl

    NASA Technical Reports Server (NTRS)

    Smith, A. H.; Besch, E. L.; Burton, R. R.

    1985-01-01

    A study of the influence of chronic acceleration on egg production of commercially raised hens placed on a large animal centrifuge at 90 days of age, was performed. S8 generation hens were stepped up from 1.25 G to 2 G, which was maintained for 30 days. Fifty percent ceased to be in the laying condition at 1.5 G, and 10.8 percent suffered oviduct prolapse above 1.8 G. S21 generation hens had no incidents of oviduct prolapse despite 170-day retention at 2 G, and, assuming a 30 percent population not in the laying condition, approximated the commercial production rate. Chronic acceleration did not appear to affect the relative sizes of albumen or yolk, but it did appear to reduce the relative shell size, consistent with a decrease in plasma calcium. Dry matter content was not affected.

  10. On the Neutron Kinetics and Control of Accelerator-Driven Systems

    SciTech Connect

    Cacuci, D.G.

    2004-09-15

    This work addresses fundamental aspects of the time- and space-dependent behavior of an Accelerator-Driven Subcritical Core System (ADS) and presents a paradigm ADS neutron kinetics model that is solved exactly. Thus, this paradigm model can serve for benchmarking two- and/or three-dimensional computational tools. Furthermore, this work also proposes a global optimal control theory framework for the operation and control of an ADS. This framework encompasses conceptually the time- and space-dependent behavior of the ADS coupled neutron kinetics/thermal-hydraulic balance equations and aims at the optimal control of ADS operational objectives, which would include minimization of local flux disturbances, load and source following, etc. Importantly, this new conceptual framework makes no use of a 'fictitious ADS steady state' and yields the correct and complete (i.e., including sources) adjoint equations, without leaving any room for ambiguities. Thus, this new conceptual framework provides a natural basis for developing new computational methods and corresponding verification experiments specifically tailored for the control and operation of ADS.

  11. Laser-driven x-ray and neutron source development for industrial applications of plasma accelerators

    NASA Astrophysics Data System (ADS)

    Brenner, C. M.; Mirfayzi, S. R.; Rusby, D. R.; Armstrong, C.; Alejo, A.; Wilson, L. A.; Clarke, R.; Ahmed, H.; Butler, N. M. H.; Haddock, D.; Higginson, A.; McClymont, A.; Murphy, C.; Notley, M.; Oliver, P.; Allott, R.; Hernandez-Gomez, C.; Kar, S.; McKenna, P.; Neely, D.

    2016-01-01

    Pulsed beams of energetic x-rays and neutrons from intense laser interactions with solid foils are promising for applications where bright, small emission area sources, capable of multi-modal delivery are ideal. Possible end users of laser-driven multi-modal sources are those requiring advanced non-destructive inspection techniques in industry sectors of high value commerce such as aerospace, nuclear and advanced manufacturing. We report on experimental work that demonstrates multi-modal operation of high power laser-solid interactions for neutron and x-ray beam generation. Measurements and Monte Carlo radiation transport simulations show that neutron yield is increased by a factor ~2 when a 1 mm copper foil is placed behind a 2 mm lithium foil, compared to using a 2 cm block of lithium only. We explore x-ray generation with a 10 picosecond drive pulse in order to tailor the spectral content for radiography with medium density alloy metals. The impact of using  >1 ps pulse duration on laser-accelerated electron beam generation and transport is discussed alongside the optimisation of subsequent bremsstrahlung emission in thin, high atomic number target foils. X-ray spectra are deconvolved from spectrometer measurements and simulation data generated using the GEANT4 Monte Carlo code. We also demonstrate the unique capability of laser-driven x-rays in being able to deliver single pulse high spatial resolution projection imaging of thick metallic objects. Active detector radiographic imaging of industrially relevant sample objects with a 10 ps drive pulse is presented for the first time, demonstrating that features of 200 μm size are resolved when projected at high magnification.

  12. Nuclear reactions with 14 MeV neutrons and bremsstrahlungs in giant dipole resonance (GDR) region using small accelerators

    NASA Astrophysics Data System (ADS)

    Thiep, Tran Duc; Van Do, Nguyen; An, Truong Thi; Son, Nguyen Ngoc

    2003-07-01

    In 1974 an accelerator of deterium, namely neutron generator NA-3-C was put into operation and in 1982 another accelerator of electron Microtron MT-17 started its work in the Institute of Physics. Though very modest these accelerators are useful for developing countries as Vietnam in both Nuclear Physics Research and Training. In this report we present some results obtained in studies on Nuclear Data, Nuclear Reactions as well as nuclear activation analysis methods. We also would like to discuss about the possibilities of collaboration in the future.

  13. Forward Neutron Production at the Fermilab Main Injector

    SciTech Connect

    Nigmanov, T.S.; Rajaram, D.; Longo, M.J.; Akgun, U.; Aydin, G.; Baker, W.; Barnes, P.D., Jr.; Bergfeld, T.; Bujak, A.; Carey, D.; Dukes, E.C.; /Virginia U. /Iowa U.

    2010-10-01

    We have measured cross sections for forward neutron production from a variety of targets using proton beams from the Fermilab Main Injector. Measurements were performed for proton beam momenta of 58 GeV/c, 84 GeV/c, and 120 GeV/c. The cross section dependence on the atomic weight (A) of the targets was found to vary as A{sup a} where a is 0.46 {+-} 0.06 for a beam momentum of 58 GeV/c and 0.54 {+-} 0.05 for 120 GeV/c. The cross sections show reasonable agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made with the LAQGSM Monte Carlo. The MIPP (Main Injector Particle Production) experiment (FNAL E907) [1] acquired data in the Meson Center beam line at Fermilab. The primary purposes of the experiment were to investigate scaling laws in hadron fragmentation [2], to obtain hadron production data for the NuMI (Neutrinos at the Main Injector [3]) target to be used for calculating neutrino fluxes, and to obtain inclusive pion, neutron, and photon production data to facilitate proton radiography [4]. While there is considerable data available on inclusive charged particle production [5], there is little data on neutron production. In this article we present results for forward neutron production using proton beams of 58 GeV/c, 84 GeV/c, and 120 GeV/c on hydrogen, beryllium, carbon, bismuth, and uranium targets, and compare these data with predictions from Monte Carlo simulations.

  14. Disk-accreting magnetic neutron stars as high-energy particle accelerators

    NASA Technical Reports Server (NTRS)

    Hamilton, Russell J.; Lamb, Frederick K.; Miller, M. Coleman

    1994-01-01

    Interaction of an accretion disk with the magnetic field of a neutron star produces large electromotive forces, which drive large conduction currents in the disk-magnetosphere-star circuit. Here we argue that such large conduction currents will cause microscopic and macroscopic instabilities in the magnetosphere. If the minimum plasma density in the magnetosphere is relatively low is less than or aproximately 10(exp 9)/cu cm, current-driven micro-instabilities may cause relativistic double layers to form, producing voltage differences in excess of 10(exp 12) V and accelerating charged particles to very high energies. If instead the plasma density is higher (is greater than or approximately = 10(exp 9)/cu cm, twisting of the stellar magnetic field is likely to cause magnetic field reconnection. This reconnection will be relativistic, accelerating plasma in the magnetosphere to relativistic speeds and a small fraction of particles to very high energies. Interaction of these high-energy particles with X-rays, gamma-rays, and accreting plasma may produce detectable high-energy radiation.

  15. Analysis of Anderson Acceleration on a Simplified Neutronics/Thermal Hydraulics System

    SciTech Connect

    Toth, Alex; Kelley, C. T.; Slattery, Stuart R; Hamilton, Steven P; Clarno, Kevin T; Pawlowski, R. P. P.

    2015-01-01

    ABSTRACT A standard method for solving coupled multiphysics problems in light water reactors is Picard iteration, which sequentially alternates between solving single physics applications. This solution approach is appealing due to simplicity of implementation and the ability to leverage existing software packages to accurately solve single physics applications. However, there are several drawbacks in the convergence behavior of this method; namely slow convergence and the necessity of heuristically chosen damping factors to achieve convergence in many cases. Anderson acceleration is a method that has been seen to be more robust and fast converging than Picard iteration for many problems, without significantly higher cost per iteration or complexity of implementation, though its effectiveness in the context of multiphysics coupling is not well explored. In this work, we develop a one-dimensional model simulating the coupling between the neutron distribution and fuel and coolant properties in a single fuel pin. We show that this model generally captures the convergence issues noted in Picard iterations which couple high-fidelity physics codes. We then use this model to gauge potential improvements with regard to rate of convergence and robustness from utilizing Anderson acceleration as an alternative to Picard iteration.

  16. MAGNETIC ENERGY PRODUCTION BY TURBULENCE IN BINARY NEUTRON STAR MERGERS

    SciTech Connect

    Zrake, Jonathan; MacFadyen, Andrew I.

    2013-06-01

    The simultaneous detection of electromagnetic and gravitational wave emission from merging neutron star binaries would greatly aid in their discovery and interpretation. By studying turbulent amplification of magnetic fields in local high-resolution simulations of neutron star merger conditions, we demonstrate that magnetar-level ({approx}> 10{sup 16} G) fields are present throughout the merger duration. We find that the small-scale turbulent dynamo converts 60% of the randomized kinetic energy into magnetic fields on a merger timescale. Since turbulent magnetic energy dissipates through reconnection events that accelerate relativistic electrons, turbulence may facilitate the conversion of orbital kinetic energy into radiation. If 10{sup -4} of the {approx}10{sup 53} erg of orbital kinetic available gets processed through reconnection and creates radiation in the 15-150 keV band, then the fluence at 200 Mpc would be 10{sup -7} erg cm{sup -2}, potentially rendering most merging neutron stars in the advanced LIGO and Virgo detection volumes detectable by Swift BAT.

  17. New empirical formula for neutron dose level at the maze entrance of 15 MV medical accelerator facilities

    SciTech Connect

    Kim, Hong-Suk; Jang, Ki-Won; Park, Youn-Hwan; Kwon, Jeong-Wan; Choi, Ho-Sin; Lee, Jai-Ki; Kim, Jong-Kyung

    2009-05-15

    An easily applicable empirical formula was derived for use in the assessment of the photoneutron dose at the maze entrance of a 15 MV medical accelerator treatment room. The neutron dose equivalent rates around the Varian medical accelerator head calculated with the Monte Carlo code MCNPX were used as the source term in producing the base data. The dose equivalents were validated by measurements with bubble detectors. Irradiation geometry conditions expected to yield higher neutron dose rates in the maze were selected: a 20x20 cm{sup 2} irradiation field, gantry rotation plane parallel to the maze walls, and the photon beams directed to the opposite wall to the maze entrance. The neutron dose equivalents at the maze entrance were computed for 697 arbitrary single-bend maze configurations by extending the Monte Carlo calculations down to the maze entrance. Then, the empirical formula was derived by a multiple regression fit to the neutron dose equivalents at the maze entrance for all the different maze configurations. The goodness of the empirical formula was evaluated by applying it to seven operating medical accelerators of different makes. When the source terms were fixed, the neutron doses estimated from the authors' formula agreed better with the corresponding MCNPX simulations than the results of the Kersey method. In addition, compared with the Wu-McGinley formula, the authors' formula provided better estimates for the mazes with length longer than 8.5 m. There are, however, discrepancies between the measured dose rates and the estimated values from the authors' formula, particularly for the machines other than a Varian model. Further efforts are needed to characterize the neutron field at the maze entrance to reduce the discrepancies. Furthermore, neutron source terms for the machines other than a Varian model should be simulated or measured and incorporated into the formula for accurate extended application to a variety of models.

  18. Radio-isotope production using laser Wakefield accelerators

    SciTech Connect

    Leemans, W.P.; Rodgers, D.; Catravas, P.E.; Geddes, C.G.R.; Fubiani, G.; Toth, C.; Esarey, E.; Shadwick, B.A.; Donahue, R.; Smith, A.; Reitsma, A.

    2001-07-27

    A 10 Hz, 10 TW solid state laser system has been used to produce electron beams suitable for radio-isotope production. The laser beam was focused using a 30 cm focal length f/6 off-axis parabola on a gas plume produced by a high pressure pulsed gas jet. Electrons were trapped and accelerated by high gradient wakefields excited in the ionized gas through the self-modulated laser wakefield instability. The electron beam was measured to contain excesses of 5 nC/bunch. A composite Pb/Cu target was used to convert the electron beam into gamma rays which subsequently produced radio-isotopes through (gamma, n) reactions. Isotope identification through gamma-ray spectroscopy and half-life time measurements demonstrated that Cu{sup 61} was produced which indicates that 20-25 MeV gamma rays were produced, and hence electrons with energies greater than 25-30 MeV. The production of high energy electrons was independently confirmed using a bending magnet spectrometer. The measured spectra had an exponential distribution with a 3 MeV width. The amount of activation was on the order of 2.5 uCi after 3 hours of operation at 1 Hz. Future experiments will aim at increasing this yield by post-accelerating the electron beam using a channel guided laser wakefield accelerator.

  19. Use of a small accelerator as a source of 14-MeV neutrons for shielding studies

    SciTech Connect

    Chapman, G.T.; Morgan, G.L.; McConnell, J.W.

    1980-11-01

    It is important in calculating complex shields such as those proposed for the fusion reactors to ascertain that the neutron cross-section data sets used in the calculations are as accurate as possible and that the calculational methods used to transport the neutrons are as reliable as practical. To assure that both these criteria are met, a project at the Oak Ridge National Laboratory (ORNL) is being conducted in which a small accelerator is used to provide 14-MeV neutrons via the T(d,n)/sup 4/He reaction and an NE-213 detector is used to measure the neutron and gamma-ray pulse-height spectra of the radiations transported through and/or created in very thick laminated shields of stainless steel (type 304) and borated polyethylene.

  20. Leading neutron production in e+p collisions at HERA

    NASA Astrophysics Data System (ADS)

    Chekanov, S.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Aghuzumtsyan, G.; Bartsch, D.; Brock, I.; Crittenden, J.; Goers, S.; Hartmann, H.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Kind, O.; Paul, E.; Rautenberg, J.; Renner, R.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Bailey, D. S.; Brook, N. H.; Cole, J. E.; Foster, B.; Heath, G. P.; Heath, H. F.; Robins, S.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Wing, M.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Kim, J. Y.; Kim, Y. K.; Lee, J. H.; Lim, I. T.; Pac, M. Y.; Caldwell, A.; Helbich, M.; Liu, X.; Mellado, B.; Paganis, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Olkiewicz, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Grabowska-Bold, I.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowal, M.; Kowalski, T.; Mindur, B.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Szuba, J.; Kotański, A.; Słomiński, W.; Bauerdick, L. A. T.; Behrens, U.; Borras, K.; Chiochia, V.; Dannheim, D.; Derrick, M.; Drews, G.; Fourletova, J.; Fox-Murphy, A.; Fricke, U.; Geiser, A.; Goebel, F.; Göttlicher, P.; Gutsche, O.; Haas, T.; Hain, W.; Hartner, G. F.; Hillert, S.; Kötz, U.; Kowalski, H.; Labes, H.; Lelas, D.; Löhr, B.; Mankel, R.; Martínez, M.; Moritz, M.; Notz, D.; Pellmann, I.-A.; Petrucci, M. C.; Polini, A.; Schneekloth, U.; Selonke, F.; Surrow, B.; Wessoleck, H.; Wichmann, R.; Wolf, G.; Youngman, C.; Zeuner, W.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Genta, C.; Pelfer, P. G.; Bamberger, A.; Benen, A.; Coppola, N.; Markun, P.; Raach, H.; Wölfle, S.; Bell, M.; Bussey, P. J.; Doyle, A. T.; Glasman, C.; Hanlon, S.; Lee, S. W.; Lupi, A.; McCance, G. J.; Saxon, D. H.; Skillicorn, I. O.; Gialas, I.; Bodmann, B.; Carli, T.; Holm, U.; Klimek, K.; Krumnack, N.; Lohrmann, E.; Milite, M.; Salehi, H.; Stonjek, S.; Wick, K.; Ziegler, A.; Ziegler, Ar; Collins-Tooth, C.; Foudas, C.; Gonçalo, R.; Long, K. R.; Metlica, F.; Miller, D. B.; Tapper, A. D.; Walker, R.; Cloth, P.; Filges, D.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Pokrovskiy, N. S.; Zhautykov, B. O.; Lim, H.; Son, D.; Barreiro, F.; González, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Vázquez, M.; Barbi, M.; Bertolin, A.; Corriveau, F.; Ochs, A.; Padhi, S.; Stairs, D. G.; St-Laurent, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, P.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Yu. A.; Katkov, I. I.; Khein, L. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Yu; Proskuryakov, A. S.; Shcheglova, L. M.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Maddox, E.; Schagen, S.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Wiggers, L.; de Wolf, E.; Brümmer, N.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Ferrando, J.; Grzelak, G.; Matsushita, T.; Rigby, M.; Ruske, O.; Sutton, M. R.; Walczak, R.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Garfagnini, A.; Limentani, S.; Longhin, A.; Parenti, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Heaphy, E. A.; Oh, B. Y.; Saull, P. R. B.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Heusch, C.; Park, I. H.; Pavel, N.; Abramowicz, H.; Dagan, S.; Gabareen, A.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Martin, J. F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J. M.; Gwenlan, C.; Hall-Wilton, R.; Jones, T. W.; Lane, J. B.; Lightwood, M. S.; Loizides, J. H.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Nowak, R. J.; Pawlak, J. M.; Smalska, B.; Sztuk, J.; Tymieniecka, T.; Ukleja, A.; Ukleja, J.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Plucinski, P.; Eisenberg, Y.; Gladilin, L. K.; Hochman, D.; Karshon, U.; Kçira, D.; Lammers, S.; Li, L.; Reeder, D. D.; Savin, A. A.; Smith, W. H.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Straub, P. B.; Bhadra, S.; Catterall, C. D.; Fourletov, S.; Khakzad, M.; Menary, S.; Soares, M.; Standage, J.; ZEUS Collaboration

    2002-08-01

    The production of neutrons carrying at least 20% of the proton beam energy ( x L> 0.2 ) in e+p collisions has been studied with the ZEUS detector at HERA for a wide range of Q2, the photon virtuality, from photoproduction to deep inelastic scattering. The neutron-tagged cross section, ep→ e' Xn, is measured relative to the inclusive cross section, ep→ e' X, thereby reducing the systematic uncertainties. For xL> 0.3, the rate of neutrons in photoproduction is about half of that measured in hadroproduction, which constitutes a clear breaking of factorisation. There is about a 20% rise in the neutron rate between photoproduction and deep inelastic scattering, which may be attributed to absorptive rescattering in the γp system. For 0.64< xL<0.82, the rate of neutrons is almost independent of the Bjorken scaling variable x and Q2. However, at lower and higher xL values, there is a clear but weak dependence on these variables, thus demonstrating the breaking of limiting fragmentation. The neutron-tagged structure function, FLN(3)2( x, Q2, xL), rises at low values of x in a way similar to that of the inclusive F2( x, Q2) of the proton. The total γπ cross section and the structure function of the pion, Fπ2( xπ, Q2) where xπ= x/(1- xL), have been determined using a one-pion-exchange model, up to uncertainties in the normalisation due to the poorly understood pion flux. At fixed Q2, Fπ2 has approximately the same x dependence as F2 of the proton.

  1. Gadolinium-148 and other spallation production cross section measurements for accelerator target facilities

    NASA Astrophysics Data System (ADS)

    Kelley, Karen Corzine

    At the Los Alamos Neutron Science Center accelerator complex, protons are accelerated to 800 MeV and directed to two tungsten targets, Target 4 at the Weapons Neutron Research facility and the 1L target at the Lujan Center. The Department of Energy requires hazard classification analyses to be performed on these targets and places limits on certain radionuclide inventories in the targets to avoid characterizing the facilities as "nuclear facilities." Gadolinium-148 is a radionuclide created from the spallation of tungsten. Allowed isotopic inventories are particularly low for this isotope because it is an alpha-particle emitter with a 75-year half-life. The activity level of Gadolinium-148 is low, but it encompasses almost two-thirds of the total dose burden for the two tungsten targets based on present yield estimates. From a hazard classification standpoint, this severely limits the lifetime of these tungsten targets. The cross section is not well-established experimentally and this is the motivation for measuring the Gadolinium-148 production cross section from tungsten. In a series of experiments at the Weapons Neutron Research facility, Gadolinium-148 production was measured for 600- and 800-MeV protons on tungsten, tantalum, and gold. These experiments used 3 mum thin tungsten, tantalum, and gold foils and 10 mum thin aluminum activation foils. In addition, spallation yields were determined for many short-lived and long-lived spallation products with these foils using gamma and alpha spectroscopy and compared with predictions of the Los Alamos National Laboratory codes CEM2k+GEM2 and MCNPX. The cumulative Gadolinium-148 production cross section measured from tantalum, tungsten, and gold for incident 600-MeV protons were 15.2 +/- 4.0, 8.31 +/- 0.92, and 0.591 +/- 0.155, respectively. The average production cross sections measured at 800 MeV were 28.6 +/- 3.5, 19.4 +/- 1.8, and 3.69 +/- 0.50 for tantalum, tungsten, and gold, respectively. These cumulative

  2. INSTRUMENTS AND METHODS OF INVESTIGATION: Giant pulses of thermal neutrons in large accelerator beam dumps. Possibilities for experiments

    NASA Astrophysics Data System (ADS)

    Stavissky, Yurii Ya

    2006-12-01

    A short review is presented of the development in Russia of intense pulsed neutron sources for physical research — the pulsating fast reactors IBR-1, IBR-30, IBR-2 (Joint Institute for Nuclear Research, Dubna), and the neutron-radiation complex of the Moscow meson factory — the 'Troitsk Trinity' (RAS Institute for Nuclear Research, Troitsk, Moscow region). The possibility of generating giant neutron pulses in beam dumps of superhigh energy accelerators is discussed. In particular, the possibility of producing giant pulsed thermal neutron fluxes in modified beam dumps of the large hadron collider (LHD) under construction at CERN is considered. It is shown that in the case of one-turn extraction ov 7-TeV protons accumulated in the LHC main rings on heavy targets with water or zirconium-hydride moderators placed in the front part of the LHC graphite beam-dump blocks, every 10 hours relatively short (from ~100 µs) thermal neutron pulses with a peak flux density of up to ~1020 neutrons cm-2 s-1 may be produced. The possibility of applying such neutron pulses in physical research is discussed.

  3. Pathways to agility in the production of neutron generators

    SciTech Connect

    Stoltz, R.E.; Beavis, L.C.; Cutchen, J.T.; Garcia, P.; Gurule, G.A.; Harris, R.N.; McKey, P.C.; Williams, D.W.

    1994-02-01

    This report is the result of a study team commissioned to explore pathways for increased agility in the manufacture of neutron generators. As a part of Sandia`s new responsibility for generator production, the goal of the study was to identify opportunities to reduce costs and increase flexibility in the manufacturing operation. Four parallel approaches (or pathways) were recommended: (1) Know the goal, (2) Use design leverage effectively, (3) Value simplicity, and (4) Configure for flexibility. Agility in neutron generator production can be enhanced if all of these pathways are followed. The key role of the workforce in achieving agility was also noted, with emphasis on ownership, continuous learning, and a supportive environment.

  4. Demonstration of a high-intensity neutron source based on a liquid-lithium target for Accelerator based Boron Neutron Capture Therapy.

    PubMed

    Halfon, S; Arenshtam, A; Kijel, D; Paul, M; Weissman, L; Berkovits, D; Eliyahu, I; Feinberg, G; Kreisel, A; Mardor, I; Shimel, G; Shor, A; Silverman, I; Tessler, M

    2015-12-01

    A free surface liquid-lithium jet target is operating routinely at Soreq Applied Research Accelerator Facility (SARAF), bombarded with a ~1.91 MeV, ~1.2 mA continuous-wave narrow proton beam. The experiments demonstrate the liquid lithium target (LiLiT) capability to constitute an intense source of epithermal neutrons, for Accelerator based Boron Neutron Capture Therapy (BNCT). The target dissipates extremely high ion beam power densities (>3 kW/cm(2), >0.5 MW/cm(3)) for long periods of time, while maintaining stable conditions and localized residual activity. LiLiT generates ~3×10(10) n/s, which is more than one order of magnitude larger than conventional (7)Li(p,n)-based near threshold neutron sources. A shield and moderator assembly for BNCT, with LiLiT irradiated with protons at 1.91 MeV, was designed based on Monte Carlo (MCNP) simulations of BNCT-doses produced in a phantom. According to these simulations it was found that a ~15 mA near threshold proton current will apply the therapeutic doses in ~1h treatment duration. According to our present results, such high current beams can be dissipated in a liquid-lithium target, hence the target design is readily applicable for accelerator-based BNCT. PMID:26300076

  5. Mechanical Design and Analysis of a 200 MHz, Bolt-together RFQ forthe Accelerator Driven Neutron Source

    SciTech Connect

    Virostek, Steve; Hoff, Matt; Li, Derun; Staples, John; Wells,Russell

    2007-06-20

    A high-yield neutron source to screen sea-land cargocontainers for shielded Special Nuclear Materials (SNM) has been designedat LBNL [1,2]. The Accelerator-Driven Neutron Source (ADNS) uses theD(d,n)3He reaction to create a forward directed neutron beam. Keycomponents are a high-current radio-frequency quadrupole (RFQ)accelerator and a high-power target capable of producing a neutron fluxof>107 n/(cm2 cdot s) at a distance of 2.5 m. The mechanical designand analysis of the four-module, bolt-together RFQ will be presentedhere. Operating at 200 MHz, the 5.1 m long RFQ will accelerate a 40 mAdeuteron beam to 6 MeV. At a 5 percent duty factor, the time-average d+beam current on target is 1.5 mA. Each of the 1.27 m long RFQ moduleswill consist of four solid OFHC copper vanes. A specially designed 3-DO-ring will provide vacuum sealing between both the vanes and themodules. RF connections are made with canted coil spring contacts. Aseries of 60 water-cooled pi-mode rods provides quadrupole modestabilization. A set of 80 evenly spaced fixed slug tuners is used forfinal frequency adjustment and local field perturbationcorrection.

  6. Be aware of neutrons outside short mazes from 10-MV linear accelerators X-rays in radiotherapy facilities.

    PubMed

    Brockstedt, S; Holstein, H; Jakobsson, L; Tomaszewicz, A; Knöös, T

    2015-07-01

    During the radiation survey of a reinstalled 10-MV linear accelerator in an old radiation treatment facility, high dose rates of neutrons were observed. The area outside the maze entrance is used as a waiting room where patients, their relatives and staff other than those involved in the actual treatment can freely pass. High fluence rates of neutrons would cause an unnecessary high effective dose to the staff working in the vicinity of such a system, and it can be several orders higher than the doses received due to X-rays at the same location. However, the common knowledge appears to have been that the effect of neutrons at 10-MV X-ray linear accelerator facilities is negligible and shielding calculations models seldom mention neutrons for this operating energy level. Although data are scarce, reports regarding this phenomenon are now emerging. For the future, it is advocated that contributions from neutrons are considered already during the planning stage of new or modified facilities aimed for 10 MV and that estimated dose levels are verified. PMID:25802465

  7. A study of 192Ir production conditions at an electron accelerator

    NASA Astrophysics Data System (ADS)

    Dovbnya, A. N.; Rogov, Yu. V.; Shevchenko, V. A.; Shramenko, B. I.; Tenishev, A. Eh.; Torgovkin, A. V.; Uvarov, V. L.

    2014-09-01

    This communication deals with the conditions of 192Ir isotope production under a nonreactor technology via the 193Ir(γ, n)192Ir reaction. It can be carried out by irradiation of a target from natural iridium with the high-energy X-ray of an electron accelerator. The possibility of increasing the photonuclear yield of the target isotope by addition of the 191Ir( n, γ)192Ir reaction induced by moderated photoneutrons has been shown. For this, an X-ray converter and a target were placed inside a neutron moderator. Data on the 192Ir and admixture yields for the techniques using the moderator and without it have been obtained by computer simulation and experimentally.

  8. Tritium implantation in the accelerator production of tritium device

    SciTech Connect

    Kidman, R.B.

    1997-11-01

    We briefly describe the methods we have developed to compute the magnitude and spatial distribution of born and implanted tritons and protons in the Accelerator Production of Tritium (AFT) device. The methods are verified against experimental measurements and then used to predict that 16% of the tritium is implanted in the walls of the APT distribution tubes. The methods are also used to estimate the spatial distribution of implanted tritium, which will be required for determining the possible diffusion of tritium out of the walls and back into the gas stream.

  9. Conceptual Design of Dielectric Accelerating Structures for Intense Neutron and Monochromatic X-ray Sources

    SciTech Connect

    Blanovsky, Anatoly

    2004-12-07

    Bright compact photon sources, which utilize electron beam interaction with periodic structures, may benefit a broad range of medical, industrial and scientific applications. A class of dielectric-loaded periodic structures for hard and soft X-ray production has been proposed that would provide a high accelerating gradient when excited by an external RF and/or primary electron beam. Target-distributed accelerators (TDA), in which an additional electric field compensates for lost beam energy in internal targets, have been shown to provide the necessary means to drive a high flux subcritical reactor (HFSR) for nuclear waste transmutation. The TDA may also be suitable for positron and nuclear isomer production, X-ray lithography and monochromatic computer tomography. One of the early assumptions of the theory of dielectric wake-field acceleration was that, in electrodynamics, the vector potential was proportional to the scalar potential. The analysis takes into consideration a wide range of TDA design aspects including the wave model of observed phenomena, a layered compound separated by a Van der Waals gap and a compact energy source based on fission electric cells (FEC) with a multistage collector. The FEC is a high-voltage power source that directly converts the kinetic energy of the fission fragments into electrical potential of about 2MV.

  10. Gold nanoparticles production using reactor and cyclotron based methods in assessment of (196,198)Au production yields by (197)Au neutron absorption for therapeutic purposes.

    PubMed

    Khorshidi, Abdollah

    2016-11-01

    Medical nano-gold radioisotopes is produced regularly using high-flux nuclear reactors, and an accelerator-driven neutron activator can turn out higher yield of (197)Au(n,γ)(196,198)Au reactions. Here, nano-gold production via radiative/neutron capture was investigated using irradiated Tehran Research Reactor flux and also simulated proton beam of Karaj cyclotron in Iran. (197)Au nano-solution, including 20nm shaped spherical gold and water, was irradiated under Tehran reactor flux at 2.5E+13n/cm(2)/s for (196,198)Au activity and production yield estimations. Meanwhile, the yield was examined using 30MeV proton beam of Karaj cyclotron via simulated new neutron activator containing beryllium target, bismuth moderator around the target, and also PbF2 reflector enclosed the moderator region. Transmutation in (197)Au nano-solution samples were explored at 15 and 25cm distances from the target. The neutron flux behavior inside the water and bismuth moderators was investigated for nano-gold particles transmutation. The transport of fast neutrons inside bismuth material as heavy nuclei with a lesser lethargy can be contributed in enhanced nano-gold transmutation with long duration time than the water moderator in reactor-based method. Cyclotron-driven production of βeta-emitting radioisotopes for brachytherapy applications can complete the nano-gold production technology as a safer approach as compared to the reactor-based method. PMID:27524041

  11. Optimal moderator materials at various proton energies considering photon dose rate after irradiation for an accelerator-driven ⁹Be(p, n) boron neutron capture therapy neutron source.

    PubMed

    Hashimoto, Y; Hiraga, F; Kiyanagi, Y

    2015-12-01

    We evaluated the accelerator beam power and the neutron-induced radioactivity of (9)Be(p, n) boron neutron capture therapy (BNCT) neutron sources having a MgF2, CaF2, or AlF3 moderator and driven by protons with energy from 8 MeV to 30 MeV. The optimal moderator materials were found to be MgF2 for proton energies less than 10 MeV because of lower required accelerator beam power and CaF2 for higher proton energies because of lower photon dose rate at the treatment position after neutron irradiation. PMID:26272165

  12. Acceleration of catalytic activity of calcium oxide for biodiesel production.

    PubMed

    Kawashima, Ayato; Matsubara, Koh; Honda, Katsuhisa

    2009-01-01

    This research was aimed at studying the acceleration of the catalytic activity of calcium oxide (CaO) for developing an effective heterogeneous catalyst for biodiesel production by the transesterification of plant oil with methanol. CaO was activated by pretreatment with methanol and was used for the transesterification reaction. The activation and transesterification reaction conditions were examined. The obtained optimal reaction conditions were 0.1-g CaO, 3.9-g methanol, 15-g rapeseed oil, and 1.5-h activation time at room temperature that provided methyl ester in approximately 90% yield within a reaction time of 3h at 60 degrees C. The activation mechanism was also investigated, and the proposed mechanism is as follows. By pretreatment with methanol, a small amount of CaO gets converted into Ca(OCH(3))(2) that acts as an initiating reagent for the transesterification reaction and produces glycerin as a by-product. Subsequently, a calcium-glycerin complex, formed due to the reaction of CaO with glycerin, functions as the main catalyst and accelerates the transesterification reaction. PMID:18684617

  13. Gas production by accelerated in situ bioleaching of landfills

    SciTech Connect

    Ghosh, S.

    1982-04-06

    A process for improved gas production and accelerated stabilization of landfills by accelerated in situ bioleaching of organic wastes by acid forming bacteria in substantially sealed landfills, passing the leachate of hydrolysis and liquefaction products of microbial action of the microorganisms with the organic material to an acid phase digester to regenerate the activated culture of acid forming microorganisms for recirculation to the landfill, passing the supernatant from the acid phase digester to a methane phase digester operated under conditions to produce methane rich gas. The supernatant from the methane phase digester containing nutrients for the acid forming microorganisms and added sewage sludge or other desired nutrient materials are circulated through the landfill. Low Btu gas is withdrawn from the acid phase digester while high Btu gas is withdrawn from the methane phase digester and may be upgraded for use as SNG. The process of this invention is applicable to small as well as large organic waste landfills, provides simultaneous disposal of municipal solid waste and sewage sludge or other aqueous organic waste in a landfill which may be stabilized much more quickly than an uncontrolled landfill as presently utilized.

  14. An investigation of the neutron flux in bone-fluorine phantoms comparing accelerator based in vivo neutron activation analysis and FLUKA simulation data

    NASA Astrophysics Data System (ADS)

    Mostafaei, F.; McNeill, F. E.; Chettle, D. R.; Matysiak, W.; Bhatia, C.; Prestwich, W. V.

    2015-01-01

    We have tested the Monte Carlo code FLUKA for its ability to assist in the development of a better system for the in vivo measurement of fluorine. We used it to create a neutron flux map of the inside of the in vivo neutron activation analysis irradiation cavity at the McMaster Accelerator Laboratory. The cavity is used in a system that has been developed for assessment of fluorine levels in the human hand. This study was undertaken to (i) assess the FLUKA code, (ii) find the optimal hand position inside the cavity and assess the effects on precision of a hand being in a non-optimal position and (iii) to determine the best location for our γ-ray detection system within the accelerator beam hall. Simulation estimates were performed using FLUKA. Experimental measurements of the neutron flux were performed using Mn wires. The activation of the wires was measured inside (1) an empty bottle, (2) a bottle containing water, (3) a bottle covered with cadmium and (4) a dry powder-based fluorine phantom. FLUKA was used to simulate the irradiation cavity, and used to estimate the neutron flux in different positions both inside, and external to, the cavity. The experimental results were found to be consistent with the Monte Carlo simulated neutron flux. Both experiment and simulation showed that there is an optimal position in the cavity, but that the effect on the thermal flux of a hand being in a non-optimal position is less than 20%, which will result in a less than 10% effect on the measurement precision. FLUKA appears to be a code that can be useful for modeling of this type of experimental system.

  15. Microwave Ion Source and Beam Injection for an Accelerator-drivenNeutron Source

    SciTech Connect

    Vainionpaa, J.H.; Gough, R.; Hoff, M.; Kwan, J.W.; Ludewigt,B.A.; Regis, M.J.; Wallig, J.G.; Wells, R.

    2007-02-15

    An over-dense microwave driven ion source capable ofproducing deuterium (or hydrogen) beams at 100-200 mA/cm2 and with atomicfraction>90 percent was designed and tested with an electrostaticlow energy beam transport section (LEBT). This ion source wasincorporatedinto the design of an Accelerator Driven Neutron Source(ADNS). The other key components in the ADNS include a 6 MeV RFQaccelerator, a beam bending and scanning system, and a deuterium gastarget. In this design a 40 mA D+ beam is produced from a 6 mm diameteraperture using a 60 kV extraction voltage. The LEBT section consists of 5electrodes arranged to form 2 Einzel lenses that focus the beam into theRFQ entrance. To create the ECR condition, 2 induction coils are used tocreate ~; 875 Gauss on axis inside the source chamber. To prevent HVbreakdown in the LEBT a magnetic field clamp is necessary to minimize thefield in this region. Matching of the microwave power from the waveguideto the plasma is done by an autotuner. We observed significantimprovement of the beam quality after installing a boron nitride linerinside the ion source. The measured emittance data are compared withPBGUNS simulations.

  16. Klystron Modulator Design for the Los Alamos Neutron Science Center Accelerator

    SciTech Connect

    Reass, William A.; Baca, David M.; Partridge, Edward R.; Rees, Daniel E.

    2012-06-22

    This paper will describe the design of the 44 modulator systems that will be installed to upgrade the Los Alamos Neutron Science Center (LANSCE) accelerator RF system. The klystrons can operate up to 86 kV with a nominal 32 Amp beam current with a 120 Hz repetition rate and 15% duty cycle. The klystrons are a mod-anode design. The modulator is designed with analog feedback control to ensure the klystron beam current is flat-top regulated. To achieve fast switching while maintaining linear feedback control, a grid-clamp, totem-pole modulator configuration is used with an 'on' deck and an 'off' deck. The on and off deck modulators are of identical design and utilize a cascode connected planar triode, cathode driven with a high speed MOSFET. The derived feedback is connected to the planar triode grid to enable the flat-top control. Although modern design approaches suggest solid state designs may be considered, the planar triode (Eimac Y-847B) is very cost effective, is easy to integrate with the existing hardware, and provides a simplified linear feedback control mechanism. The design is very compact and fault tolerant. This paper will review the complete electrical design, operational performance, and system characterization as applied to the LANSCE installation.

  17. Lorentz force detuning analysis of the Spallation Neutron Source (SNS) accelerating cavities.

    SciTech Connect

    Mitchell, R.R.; Matsumoto, K. Y.; Ciovati, G.; Davis, K.; Macha, K.; Sundelin, R. M.

    2001-01-01

    The Spallation Neutron Source (SNS) project incorporates a superconducting radio-frequency (SRF) accelerator for the final section of the pulsed mode linac. Cavities with geometrical {beta} values of {beta}=0.61 and {beta}=0.81 are utilized in the SRF section, and are constructed out of thin-walled niobium with stiffener rings welded between the cells near the iris. The welded titanium helium vessel and tuner assembly restrains the cavity beam tubes. Cavities with {beta} values less than one have relatively steep and flat side-walls making the cavities susceptible to Lorentz force detuning. In addition, the pulsed RF induces cyclic Lorentz pressures that mechanically excite the cavities, producing a dynamic Lorentz force detuning different from a continuous RF system. The amplitude of the dynamic detuning for a given cavity design is a function of the mechanical damping, stiffness of the tuner/helium vessel assembly, RF pulse profile, and the RF pulse rate. This paper presents analysis and testing results to date, and indicates areas where more investigation is required.

  18. Neutron Cross Section Covariances for Structural Materials and Fission Products

    NASA Astrophysics Data System (ADS)

    Hoblit, S.; Cho, Y.-S.; Herman, M.; Mattoon, C. M.; Mughabghab, S. F.; Obložinský, P.; Pigni, M. T.; Sonzogni, A. A.

    2011-12-01

    We describe neutron cross section covariances for 78 structural materials and fission products produced for the new US evaluated nuclear reaction library ENDF/B-VII.1. Neutron incident energies cover full range from 10 eV to 20 MeV and covariances are primarily provided for capture, elastic and inelastic scattering as well as (n,2n). The list of materials follows priorities defined by the Advanced Fuel Cycle Initiative, the major application being data adjustment for advanced fast reactor systems. Thus, in addition to 28 structural materials and 49 fission products, the list includes also 23Na which is important fast reactor coolant. Due to extensive amount of materials, we adopted a variety of methodologies depending on the priority of a specific material. In the resolved resonance region we primarily used resonance parameter uncertainties given in Atlas of Neutron Resonances and either applied the kernel approximation to propagate these uncertainties into cross section uncertainties or resorted to simplified estimates based on integral quantities. For several priority materials we adopted MF32 covariances produced by SAMMY at ORNL, modified by us by adding MF33 covariances to account for systematic uncertainties. In the fast neutron region we resorted to three methods. The most sophisticated was EMPIRE-KALMAN method which combines experimental data from EXFOR library with nuclear reaction modeling and least-squares fitting. The two other methods used simplified estimates, either based on the propagation of nuclear reaction model parameter uncertainties or on a dispersion analysis of central cross section values in recent evaluated data files. All covariances were subject to quality assurance procedures adopted recently by CSEWG. In addition, tools were developed to allow inspection of processed covariances and computed integral quantities, and for comparing these values to data from the Atlas and the astrophysics database KADoNiS.

  19. Neutron Cross Section Covariances for Structural Materials and Fission Products

    SciTech Connect

    Hoblit, S.; Hoblit,S.; Cho,Y.-S.; Herman,M.; Mattoon,C.M.; Mughabghab,S.F.; Oblozinsky,P.; Pigni,M.T.; Sonzogni,A.A.

    2011-12-01

    We describe neutron cross section covariances for 78 structural materials and fission products produced for the new US evaluated nuclear reaction library ENDF/B-VII.1. Neutron incident energies cover full range from 10{sup -5} eV to 20 MeV and covariances are primarily provided for capture, elastic and inelastic scattering as well as (n,2n). The list of materials follows priorities defined by the Advanced Fuel Cycle Initiative, the major application being data adjustment for advanced fast reactor systems. Thus, in addition to 28 structural materials and 49 fission products, the list includes also {sup 23}Na which is important fast reactor coolant. Due to extensive amount of materials, we adopted a variety of methodologies depending on the priority of a specific material. In the resolved resonance region we primarily used resonance parameter uncertainties given in Atlas of Neutron Resonances and either applied the kernel approximation to propagate these uncertainties into cross section uncertainties or resorted to simplified estimates based on integral quantities. For several priority materials we adopted MF32 covariances produced by SAMMY at ORNL, modified by us by adding MF33 covariances to account for systematic uncertainties. In the fast neutron region we resorted to three methods. The most sophisticated was EMPIRE-KALMAN method which combines experimental data from EXFOR library with nuclear reaction modeling and least-squares fitting. The two other methods used simplified estimates, either based on the propagation of nuclear reaction model parameter uncertainties or on a dispersion analysis of central cross section values in recent evaluated data files. All covariances were subject to quality assurance procedures adopted recently by CSEWG. In addition, tools were developed to allow inspection of processed covariances and computed integral quantities, and for comparing these values to data from the Atlas and the astrophysics database KADoNiS.

  20. [Relative biological effectiveness of accelerated heavy ions and fast neutrons estimated from frequency of aberration mytoses in the retinal epithelium].

    PubMed

    Vorozhtsova, S V; Shafirkin, A V; Fedorenko, B S

    2006-01-01

    Analyzed was the literature and authors' experimental data concerning lesion and recovery of epithelium cells of mice retina immediately and long after irradiation at different sources including single and partly fractionated irradiation by gamma- and X-rays, accelerated protons, helium, carbon and boron ions, and fast neutrons of the reactor range in a large spectrum of doses and LET. Reviewed are some new techniques of determining the RBE coefficient for these types of radiation; large values of the RBE coefficients for accelerated ions and neutrons (5-10 times higher than RBE coefficients calculated for the next day following irradiation) are a result of integration into calculation of the available data about the delayed disorders in retinal epithelium cell regeneration. PMID:17193969

  1. γ production and neutron inelastic scattering cross sections for 76Ge

    NASA Astrophysics Data System (ADS)

    Rouki, C.; Domula, A. R.; Drohé, J. C.; Koning, A. J.; Plompen, A. J. M.; Zuber, K.

    2013-11-01

    The 2040.7-keV γ ray from the 69th excited state of 76Ge was investigated in the interest of Ge-based double-β-decay experiments like the Germanium Detector Array (GERDA) experiment. The predicted transition could interfere with valid 0νββ events at 2039.0 keV, creating false signals in large-volume 76Ge enriched detectors. The measurement was performed with the Gamma Array for Inelastic Neutron Scattering (GAINS) at the Geel Electron Linear Accelerator (GELINA) white neutron source, using the (n,n'γ) technique and focusing on the strongest γ rays originating from the level. Upper limits obtained for the production cross section of the 2040.7-keV γ ray showed no possible influence on GERDA data. Additional analysis of the data yielded high-resolution cross sections for the low-lying states of 76Ge and related γ rays, improving the accuracy and extending existing data for five transitions and five levels. The inelastic scattering cross section for 76Ge was determined for incident neutron energies up to 2.23 MeV, significantly increasing the energy range for which experimental data are available. Comparisons with model calculations using the talys code are presented indicating that accounting for the recently established asymmetric rotor structure should lead to an improved description of the data.

  2. Ambient neutron dose equivalent outside concrete vault rooms for 15 and 18 MV radiotherapy accelerators.

    PubMed

    Martínez-Ovalle, S A; Barquero, R; Gómez-Ros, J M; Lallena, A M

    2012-03-01

    In this work, the ambient dose equivalent, H*(10), due to neutrons outside three bunkers that house a 15- and a 18-MV Varian Clinac 2100C/D and a 15-MV Elekta Inor clinical linacs, has been calculated. The Monte Carlo code MCNPX (v. 2.5) has been used to simulate the neutron production and transport. The complete geometries including linacs and full installations have been built up according to the specifications of the manufacturers and the planes provided by the corresponding medical physical services of the hospitals where the three linacs operate. Two of these installations, those lodging the Varian linacs, have an entrance door to the bunker while the other one does not, although it has a maze with two bends. Various treatment orientations were simulated in order to establish plausible annual equivalent doses. Specifically anterior-posterior, posterior-anterior, left lateral, right lateral orientations and an additional one with the gantry rotated 30° have been studied. Significant dose rates have been found only behind the walls and the door of the bunker, near the entrance and the console, with a maximum of 12 µSv h(-1). Dose rates per year have been calculated assuming a conservative workload for the three facilities. The higher dose rates in the corresponding control areas were 799 µSv y(-1), in the case of the facility which operates the 15-MV Clinac, 159 µSv y(-1), for that with the 15-MV Elekta, and 21 µSv y(-1) for the facility housing the 18-MV Varian. A comparison with measurements performed in similar installations has been carried out and a reasonable agreement has been found. The results obtained indicate that the neutron contamination does not increase the doses above the legal limits and does not produce a significant enhancement of the dose equivalent calculated. When doses are below the detection limits provided by the measuring devices available today, MCNPX simulation provides an useful method to evaluate neutron dose equivalents based

  3. Advances in boron neutron capture therapy (BNCT) at kyoto university - From reactor-based BNCT to accelerator-based BNCT

    NASA Astrophysics Data System (ADS)

    Sakurai, Yoshinori; Tanaka, Hiroki; Takata, Takushi; Fujimoto, Nozomi; Suzuki, Minoru; Masunaga, Shinichiro; Kinashi, Yuko; Kondo, Natsuko; Narabayashi, Masaru; Nakagawa, Yosuke; Watanabe, Tsubasa; Ono, Koji; Maruhashi, Akira

    2015-07-01

    At the Kyoto University Research Reactor Institute (KURRI), a clinical study of boron neutron capture therapy (BNCT) using a neutron irradiation facility installed at the research nuclear reactor has been regularly performed since February 1990. As of November 2014, 510 clinical irradiations were carried out using the reactor-based system. The world's first accelerator-based neutron irradiation system for BNCT clinical irradiation was completed at this institute in early 2009, and the clinical trial using this system was started in 2012. A shift of BCNT from special particle therapy to a general one is now in progress. To promote and support this shift, improvements to the irradiation system, as well as its preparation, and improvements in the physical engineering and the medical physics processes, such as dosimetry systems and quality assurance programs, must be considered. The recent advances in BNCT at KURRI are reported here with a focus on physical engineering and medical physics topics.

  4. Beam dynamics study of a 30 MeV electron linear accelerator to drive a neutron source

    SciTech Connect

    Kumar, Sandeep; Yang, Haeryong; Kang, Heung-Sik

    2014-02-14

    An experimental neutron facility based on 32 MeV/18.47 kW electron linac has been studied by means of PARMELA simulation code. Beam dynamics study for a traveling wave constant gradient electron accelerator is carried out to reach the preferential operation parameters (E = 30 MeV, P = 18 kW, dE/E < 12.47% for 99% particles). The whole linac comprises mainly E-gun, pre-buncher, buncher, and 2 accelerating columns. A disk-loaded, on-axis-coupled, 2π/3-mode type accelerating rf cavity is considered for this linac. After numerous optimizations of linac parameters, 32 MeV beam energy is obtained at the end of the linac. As high electron energy is required to produce acceptable neutron flux. The final neutron flux is estimated to be 5 × 10{sup 11} n/cm{sup 2}/s/mA. Future development will be the real design of a 30 MeV electron linac based on S band traveling wave.

  5. Gluon saturation and Feynman scaling in leading neutron production

    NASA Astrophysics Data System (ADS)

    Carvalho, F.; Gonçalves, V. P.; Spiering, D.; Navarra, F. S.

    2016-01-01

    In this paper we extend the color dipole formalism for the study of leading neutron production in e + p → e + n + X collisions at high energies and estimate the related observables which were measured at HERA and could be analyzed in future electron-proton (ep) colliders. In particular, we calculate the Feynman xF distribution of leading neutrons, which is expressed in terms of the pion flux and the photon-pion total cross section. In the color dipole formalism, the photon-pion cross section is described in terms of the dipole-pion scattering amplitude, which contains information about the QCD dynamics at high energies and gluon saturation effects. We consider different models for the scattering amplitude, which have been used to describe the inclusive and diffractive ep HERA data. Moreover, the model dependence of our predictions with the description of the pion flux is analyzed in detail. We demonstrate the recently released H1 leading neutron spectra can be described using the color dipole formalism and that these spectra could help us to observe more clearly gluon saturation effects in future ep colliders.

  6. METHOD OF PRODUCING ENERGETIC PLASMA FOR NEUTRON PRODUCTION

    DOEpatents

    Bell, P.R.; Simon, A.; Mackin, R.J. Jr.

    1961-01-24

    A method is given for producing an energetic plasma for neutron production. An energetic plasma is produced in a small magnetically confined subvolume of the device by providing a selected current of energetic molecular ions at least greater than that required for producing a current of atomic ions sufficient to achieve "burnout" of neutral particles in the subvolume. The atomic ions are provided by dissociation of the molecular ions by an energetic arc discharge within the subvolume. After burnout, the arc discharge is terminated, the magnetic fields increased, and cold fuel feed is substituted for the molecular ions. After the subvolume is filled with an energetic plasma, the size of the magnetically confined subvolume is gradually increased until the entire device is filled with an energetic neutron producing plasma. The reactions which take place in the device to produce neutrons will generate a certain amount of heat energy which may be converted by the use of a conventional heat cycle to produce electrical energy.

  7. Examination of radioargon production by cosmic neutron interactions.

    PubMed

    Johnson, Christine; Armstrong, Hirotatsu; Wilson, William H; Biegalski, Steven R

    2015-02-01

    Radioargon isotopes, particularly (37)Ar, are currently being considered for use as an On-Site Inspection (OSI) relevant radionuclide within the context of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). In order to understand any soil air measurements taken during an OSI, the radioargon background due to cosmic ray induced activation along with other sources must be understood. An MCNP6 model was developed using the cosmic ray source feature within the code to examine the neutron flux at ground level as a function of various conditions: date during the solar magnetic activity cycle, latitude of sampling location, geology of the sampling location, and sampling depth. Once the cosmic neutron flux was obtained, calculations were performed to determine the rate of radioargon production for the main interactions. Radioargon production was shown to be highly dependent on the soil composition, and a range of (37)Ar production values at 1 m depth was found with a maximum production rate of 4.012 atoms/sec/m(3) in carbonate geologies and a minimum production rate of 0.070 atoms/sec/m(3) in low calcium granite. The sampling location latitude was also shown to have a measurable effect on the radioargon production rate, where the production of (37)Ar in an average continental crust is shown to vary by a factor of two between the equator and the poles. The sampling date's position within the solar magnetic activity cycle was also shown to cause a smaller change, less than a factor of 1.2, in activation between solar maxima and solar minima. PMID:25461524

  8. Out-of-field doses and neutron dose equivalents for electron beams from modern Varian and Elekta linear accelerators.

    PubMed

    Cardenas, Carlos E; Nitsch, Paige L; Kudchadker, Rajat J; Howell, Rebecca M; Kry, Stephen F

    2016-01-01

    Out-of-field doses from radiotherapy can cause harmful side effects or eventually lead to secondary cancers. Scattered doses outside the applicator field, neutron source strength values, and neutron dose equivalents have not been broadly investigated for high-energy electron beams. To better understand the extent of these exposures, we measured out-of-field dose characteristics of electron applicators for high-energy electron beams on two Varian 21iXs, a Varian TrueBeam, and an Elekta Versa HD operating at various energy levels. Out-of-field dose profiles and percent depth-dose curves were measured in a Wellhofer water phantom using a Farmer ion chamber. Neutron dose was assessed using a combination of moderator buckets and gold activation foils placed on the treatment couch at various locations in the patient plane on both the Varian 21iX and Elekta Versa HD linear accelerators. Our findings showed that out-of-field electron doses were highest for the highest electron energies. These doses typically decreased with increasing distance from the field edge but showed substantial increases over some distance ranges. The Elekta linear accelerator had higher electron out-of-field doses than the Varian units examined, and the Elekta dose profiles exhibited a second dose peak about 20 to 30 cm from central-axis, which was found to be higher than typical out-of-field doses from photon beams. Electron doses decreased sharply with depth before becoming nearly constant; the dose was found to decrease to a depth of approximately E(MeV)/4 in cm. With respect to neutron dosimetry, Q values and neutron dose equivalents increased with electron beam energy. Neutron contamination from electron beams was found to be much lower than that from photon beams. Even though the neutron dose equivalent for electron beams represented a small portion of neutron doses observed under photon beams, neutron doses from electron beams may need to be considered for special cases. PMID:27455499

  9. The design of an intense accelerator-based epithermal neutron beam prototype for BNCT using near-threshold reactions

    NASA Astrophysics Data System (ADS)

    Lee, Charles L.

    Near-threshold boron neutron capture therapy (BNCT) uses proton energies only tens of rev above the (pan) reaction threshold in lithium in order to reduce the moderation requirements of the neutron source. The goals of this research were to prove the feasibility of this near-threshold concept for BNCT applications, using both calculation and experiment, and design a compact neutron source prototype from these results. This required a multidisciplinary development of methods for calculation of neutron yields, head phantom dosimetry, and accelerator target heat removal. First, a method was developed to accurately calculate thick target neutron yields for both near-threshold and higher energy proton beams, in lithium metal as well as lithium compounds. After these yields were experimentally verified, they were used as neutron sources for Monte Carlo (MCNP) simulations of neutron and photon transport in head phantoms. The theoretical and experimental determination of heat removal from a target backing with multiple fins, as well as numerical calculations of heat deposition profiles based on proton energy loss in target and backing materials, demonstrated that lithium integrity can be maintained for proton beam currents up to 2.5 mA. The final design uses a proton beam energy of 1.95 MeV and has a centerline epithermal neutron flux of 2.2 × 108 n/cm2- sec/mA, an advantage depth of 5.7 cm, an advantage ratio of 4.3, and an advantage depth dose rate of 6.7 RBE- cGy/min/mA, corresponding to an irradiation time of 38 minutes with a 5 mA beam. Moderator, reflector, and shielding weigh substantially less than other accelerator BNCT designs based on higher proton energies, e.g. 2.5 MeV. The near-threshold concept is useful as a portable neutron source for hospital settings, with applications ranging from glioblastomas to melanomas and synovectomy. (Copies available exclusively from MIT Libraries, Rm. 14- 0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

  10. Solar neutrons and the energy spectrum of flare-accelerated particles

    NASA Astrophysics Data System (ADS)

    Kocharov, G. E.; Mandzhavidze, N. Z.

    1987-10-01

    The Monte Carlo method is used to calculate the generation and escape of neutrons in the framework of the magnetic-arc model. It is shown that the generation of neutrons lasts for 20-30 minutes; the characteristic time of the intensity decline increases with magnetic field gradient and the radius of the coronal part of the arc. The angular distribution of escaping neutrons is anisotropic, with the maximum flux occurring at the limb. The neutron energy spectra are different in different directions. Particular attention is given to the solar-longitude dependence of neutron fluxes in a flare with gamma-ray emission.

  11. Neutron Activation Analysis and Product Isotope Inventory Code System.

    1990-10-31

    Version 00 NAC was designed to predict the neutron-induced gamma-ray radioactivity for a wide variety of composite materials. The NAC output includes the input data, a list of all reactions for each constituent element, and the end-of-irradiation disintegration rates for each reaction. NAC also compiles a product isotope inventory containing the isotope name, the disintegration rate, the gamma-ray source strength, and the absorbed dose rate at 1 meter from an unshielded point source. The inducedmore » activity is calculated as a function of irradiation and decay times; the effect of cyclic irradiation can also be calculated.« less

  12. Benchmarking of Neutron Production of Heavy-Ion Transport Codes

    SciTech Connect

    Remec, Igor; Ronningen, Reginald M.; Heilbronn, Lawrence

    2012-01-01

    Accurate prediction of radiation fields generated by heavy ion interactions is important in medical applications, space missions, and in design and operation of rare isotope research facilities. In recent years, several well-established computer codes in widespread use for particle and radiation transport calculations have been equipped with the capability to simulate heavy ion transport and interactions. To assess and validate these capabilities, we performed simulations of a series of benchmark-quality heavy ion experiments with the computer codes FLUKA, MARS15, MCNPX, and PHITS. We focus on the comparisons of secondary neutron production. Results are encouraging; however, further improvements in models and codes and additional benchmarking are required.

  13. Forward neutron production at the Fermilab Main Injector

    SciTech Connect

    Nigmanov, T. S.; Rajaram, D.; Longo, M. J.; Gustafson, H. R.; Park, H. K.; Akgun, U.; Aydin, G.; Duru, F.; Guelmez, E.; Guenaydin, Y. O.; Onel, Y.; Penzo, A.; Baker, W.; Carey, D.; Johnstone, C.; Kostin, M.; Raja, R.; Barnes, P. D. Jr.; Hartouni, E.; Heffner, M.

    2011-01-01

    We have measured cross sections for forward neutron production from a variety of targets using proton beams from the Fermilab Main Injector. Measurements were performed for proton beam momenta of 58, 84, and 120 GeV/c. The cross section dependence on the atomic weight (A) of the targets was found to vary as A{sup {alpha}}, where {alpha} is 0.46{+-}0.06 for a beam momentum of 58 GeV/c and 0.54{+-}0.05 for 120 GeV/c. The cross sections show reasonable agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made with the LAQGSM Monte Carlo.

  14. Highly Productive Application Development with ViennaCL for Accelerators

    NASA Astrophysics Data System (ADS)

    Rupp, K.; Weinbub, J.; Rudolf, F.

    2012-12-01

    The use of graphics processing units (GPUs) for the acceleration of general purpose computations has become very attractive over the last years, and accelerators based on many integrated CPU cores are about to hit the market. However, there are discussions about the benefit of GPU computing when comparing the reduction of execution times with the increased development effort [1]. To counter these concerns, our open-source linear algebra library ViennaCL [2,3] uses modern programming techniques such as generic programming in order to provide a convenient access layer for accelerator and GPU computing. Other GPU-accelerated libraries are primarily tuned for performance, but less tailored to productivity and portability: MAGMA [4] provides dense linear algebra operations via a LAPACK-comparable interface, but no dedicated matrix and vector types. Cusp [5] is closest in functionality to ViennaCL for sparse matrices, but is based on CUDA and thus restricted to devices from NVIDIA. However, no convenience layer for dense linear algebra is provided with Cusp. ViennaCL is written in C++ and uses OpenCL to access the resources of accelerators, GPUs and multi-core CPUs in a unified way. On the one hand, the library provides iterative solvers from the family of Krylov methods, including various preconditioners, for the solution of linear systems typically obtained from the discretization of partial differential equations. On the other hand, dense linear algebra operations are supported, including algorithms such as QR factorization and singular value decomposition. The user application interface of ViennaCL is compatible to uBLAS [6], which is part of the peer-reviewed Boost C++ libraries [7]. This allows to port existing applications based on uBLAS with a minimum of effort to ViennaCL. Conversely, the interface compatibility allows to use the iterative solvers from ViennaCL with uBLAS types directly, thus enabling code reuse beyond CPU-GPU boundaries. Out-of-the-box support

  15. Hadron production measurements to constrain accelerator neutrino beams

    SciTech Connect

    Korzenev, Alexander

    2015-07-15

    A precise prediction of expected neutrino fluxes is required for a long-baseline accelerator neutrino experiment. The flux is used to measure neutrino cross sections at the near detector, while at the far detector it provides an estimate of the expected signal for the study of neutrino oscillations. In the talk several approaches to constrain the ν flux are presented. The first is the traditional one when an interaction chain for the neutrino parent hadrons is stored to be weighted later with real measurements. In this approach differential hadron cross sections are used which, in turn, are measured in ancillary hadron production experiments. The approach is certainly model dependent because it requires an extrapolation to different incident nucleon momenta assuming x{sub F} scaling as well as extrapolation between materials having different atomic numbers. In the second approach one uses a hadron production yields off a real target exploited in the neutrino beamline. Yields of neutrino parent hadrons are parametrized at the surface of the target, thus one avoids to trace the particle interaction history inside the target. As in the case of the first approach, a dedicated ancillary experiment is mandatory. Recent results from the hadron production experiments – NA61/SHINE at CERN (measurements for T2K) and MIPP at Fermilab (measurements for NuMI) – are reviewed.

  16. Hadron production measurements to constrain accelerator neutrino beams

    NASA Astrophysics Data System (ADS)

    Korzenev, Alexander

    2015-07-01

    A precise prediction of expected neutrino fluxes is required for a long-baseline accelerator neutrino experiment. The flux is used to measure neutrino cross sections at the near detector, while at the far detector it provides an estimate of the expected signal for the study of neutrino oscillations. In the talk several approaches to constrain the ν flux are presented. The first is the traditional one when an interaction chain for the neutrino parent hadrons is stored to be weighted later with real measurements. In this approach differential hadron cross sections are used which, in turn, are measured in ancillary hadron production experiments. The approach is certainly model dependent because it requires an extrapolation to different incident nucleon momenta assuming xF scaling as well as extrapolation between materials having different atomic numbers. In the second approach one uses a hadron production yields off a real target exploited in the neutrino beamline. Yields of neutrino parent hadrons are parametrized at the surface of the target, thus one avoids to trace the particle interaction history inside the target. As in the case of the first approach, a dedicated ancillary experiment is mandatory. Recent results from the hadron production experiments - NA61/SHINE at CERN (measurements for T2K) and MIPP at Fermilab (measurements for NuMI) - are reviewed.

  17. Final Report US-Japan IEC Workshop on Small Plasma and Accelerator Neutron Sources

    SciTech Connect

    Miley, George, H.

    2008-06-04

    Abstract The history of IEC development will be briefly described, and some speculation about future directions will be offered. The origin of IEC is due to the brilliance of Phil Farnsworth, inventor of electronic TV in the US. Early experiments were pioneered in the late 1960s by Robert Hirsch who later became head of the DOE fusion program. At that time studies of IEC physics quickly followed at the University of Illinois and at Penn State University. However, despite many successes in this early work, IEC research died as DOE funding stopped in the mid 1980s. In the early 90’s, R. W. Bussard of EMC revived work with a new major project based on a magnetic assisted IEC. While doing supportive studies for that project, G. Miley proposed a grided “STAR mode” IEC as a neutron source for NAA. This concept was later used commercially by Daimler- Benz in Germany to analysis impurities in incoming ores. This represented a first practical application of the IEC. During this period other research groups at LANL, U of Wisconsin and Kyoto University entered IEC research with innovative new concepts and approaches to IEC physics and applications. Much of this work is documented in the present and in past US-Japan Workshops. At present we stand on the threshold of a new area of IEC applications as neutron source, for isotope production, and as a plasma source. These applications provide a way to continue IEC understanding and technology development with the ultimate goal being a fusion power plant. Indeed, a distinguishing feature of the IEC vs. other fusion confinement approaches is the unique opportunity for “spin off” applications along the way to a power producing plant.

  18. Plasma production for electron acceleration by resonant plasma wave

    NASA Astrophysics Data System (ADS)

    Anania, M. P.; Biagioni, A.; Chiadroni, E.; Cianchi, A.; Croia, M.; Curcio, A.; Di Giovenale, D.; Di Pirro, G. P.; Filippi, F.; Ghigo, A.; Lollo, V.; Pella, S.; Pompili, R.; Romeo, S.; Ferrario, M.

    2016-09-01

    Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV/m), enabling acceleration of electrons to GeV energy in few centimeter. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators (large energy spread, low repetition rate, and large emittance); radiofrequency-based accelerators, in fact, are limited in accelerating field (10-100 MV/m) requiring therefore hundred of meters of distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC_LAB (Ferrario et al., 2013 [1]). In particular here we focus on hydrogen plasma discharge, and in particular on the theoretical and numerical estimates of the ionization process which are very useful to design the discharge circuit and to evaluate the current needed to be supplied to the gas in order to have full ionization. Eventually, the current supplied to the gas simulated will be compared to that measured experimentally.

  19. Evaluation of photon production data from neutron-induced reactions

    SciTech Connect

    Fu, C.Y.

    1980-01-01

    The evaluation methods and procedures used for generating the photon production data in the current Evaluated Nuclear Data File (ENDF/B, Version V) are reviewed. There are 42 materials in the General Purpose File of ENDF/B-V that contain data for prompt photon production. Almost all evaluations had substantial experimental data bases, but fewer than half of them employed any of the following evaluation methods. Only a few used theoretical techniques that are sophisticated enough to ensure internal consistency with other particle production data. Comments are made on four evaluation methods: the empirical formalism of Howerton et al., the Troubetzkoy model, the multiparticle Hauser-Feshbach/precompound model, and the Yost method. Critiques are also made on three procedures used for conserving photon energies in neutron capture reactions. The presence of photon production data in the file is useful for studying energy balance, since photon production generally accounts for a large portion of the reaction energy output. Problems found in energy balance checks are discussed. 9 figures, 1 table.

  20. Accelerator-based neutron source using a cold deuterium target with degenerate electrons

    SciTech Connect

    Phillips, R. E.; Ordonez, C. A.

    2013-07-15

    A neutron generator is considered in which a beam of tritons is incident on a hypothetical cold deuterium target with degenerate electrons. The energy efficiency of neutron generation is found to increase substantially with electron density. Recent reports of potential targets are discussed.

  1. The relationship between contrast, resolution and detectability in accelerator-based fast neutron radiography

    SciTech Connect

    Ambrosi, R. M.; Watterson, J. I. W.

    1999-06-10

    Fast neutron radiography as a method for non destructive testing is a fast growing field of research. At the Schonland Research Center for Nuclear Sciences we have been engaged in the formulation of a model for the physics of image formation in fast neutron radiography (FNR). This involves examining all the various factors that affect image formation in FNR by experimental and Monte Carlo methods. One of the major problems in the development of a model for fast neutron radiography is the determination of the factors that affect image contrast and resolution. Monte Carlo methods offer an ideal tool for the determination of the origin of many of these factors. In previous work the focus of these methods has been the determination of the scattered neutron field in both a scintillator and a fast neutron radiography facility. As an extension of this work MCNP has been used to evaluate the role neutron scattering in a specimen plays in image detectability. Image processing of fast neutron radiographs is a necessary method of enhancing the detectability of features in an image. MCNP has been used to determine the part it can play in indirectly improving image resolution and aiding in image processing. The role noise plays in fast neutron radiography and its impact on image reconstruction has been evaluated. All these factors aid in the development of a model describing the relationship between contrast, resolution and detectability.

  2. Novel production techniques of radioisotopes using electron accelerators

    NASA Astrophysics Data System (ADS)

    Lowe, Daniel Robert

    Non-traditional radioisotope production techniques using a compact, high power linear electron accelerator have been demonstrated and characterized for the production of 18F, 47Sc, 147 Pm, and 99mTc from a variety of target candidates. These isotopes are used extensively in the medical field as diagnostic and therapy radioisotopes, as well as the space industry as RTG's. Primary focus was placed on 99mTc as it constitutes approximately 80% of all diagnostic procedures in the medical community that use radioactive tracers. It was also the prime focus due to recent events at the Chalk River nuclear reactor, which caused global shortages of this isotope a few years ago. A Varian K15 LINAC was first used to show proof of principle in Las Vegas. Various samples were then taken to the Idaho Accelerator Center where they were activated using an electron LINAC capable of electron energies from 4 to 25 MeV at a beam power of approximately 1 kW. Production rates, cross sections, and viability studies were then performed and conducted to assess the effectiveness of the candidate target and the maximum production rate for each radioisotope. Production rates for 18F from lithium fluoride salts were shown to be ideal at 21MeV, namely 1.7 Ci per kg of LiF salt, per kW of beam current, per 10 hour irradiation time. As the typical hospital consumption of 18F is around 500 mCi per day, it is clear that a large amount of 18F can be made from a small (300 gram) sample of LiF salt. However, since there is no current separation process for 18F from 19F, the viability of this technique is limited until a separations technique is developed. Furthermore, the calculated cross section for this reaction is in good agreement with literature, which supports the techniques for the isotopes mentioned below. Production rates for 47Sc from vanadium oxide targets were shown to be a maximum at 25 MeV with a production rate of 2 mCi per day, assuming a 2 kW beam and a 10 kg target. While this

  3. Development of a cryogenic load frame for the neutron diffractometer at Takumi in Japan Proton Accelerator Research Complex

    SciTech Connect

    Jin, Xinzhe; Nakamoto, Tatsushi; Ogitsu, Toru; Yamamoto, Akira; Sugano, Michinaka; Harjo, Stefanus; Aizawa, Kazuya; Abe, Jun; Gong, Wu; Iwahashi, Takaaki; Hemmi, Tsutomu; Umeno, Takahiro

    2013-06-15

    To prepare for projects such as the Large Hadron Collider upgrade, International Thermonuclear Experimental Reactor and Demonstration reactor, it is important to form a clear understanding of stress-strain properties of the materials that make up superconducting magnets. Thus, we have been studying the mechanical properties of superconducting wires using neutron diffraction measurements. To simulate operational conditions such as temperature, stress, and strain, we developed a cryogenic load frame for stress-strain measurements of materials using a neutron diffractometer at Japan Proton Accelerator Research Complex (J-PARC) Takumi beam line. The maximum load that can be applied to a sample using an external driving machine is 50 kN. Using a Gifford-MacMahon cryocooler, samples can be measured down to temperatures below 10 K when loaded. In the present paper, we describe the details of the cryogenic load frame with its test results by using type-304 stainless steel wire.

  4. Development of a cryogenic load frame for the neutron diffractometer at Takumi in Japan Proton Accelerator Research Complex.

    PubMed

    Jin, Xinzhe; Nakamoto, Tatsushi; Harjo, Stefanus; Hemmi, Tsutomu; Umeno, Takahiro; Ogitsu, Toru; Yamamoto, Akira; Sugano, Michinaka; Aizawa, Kazuya; Abe, Jun; Gong, Wu; Iwahashi, Takaaki

    2013-06-01

    To prepare for projects such as the Large Hadron Collider upgrade, International Thermonuclear Experimental Reactor and Demonstration reactor, it is important to form a clear understanding of stress-strain properties of the materials that make up superconducting magnets. Thus, we have been studying the mechanical properties of superconducting wires using neutron diffraction measurements. To simulate operational conditions such as temperature, stress, and strain, we developed a cryogenic load frame for stress-strain measurements of materials using a neutron diffractometer at Japan Proton Accelerator Research Complex (J-PARC) Takumi beam line. The maximum load that can be applied to a sample using an external driving machine is 50 kN. Using a Gifford-MacMahon cryocooler, samples can be measured down to temperatures below 10 K when loaded. In the present paper, we describe the details of the cryogenic load frame with its test results by using type-304 stainless steel wire. PMID:23822332

  5. Production cross section of neutron-rich isotopes with radioactive and stable beams

    NASA Astrophysics Data System (ADS)

    Mun, Myeong-Hwan; Adamian, G. G.; Antonenko, N. V.; Oh, Yongseok; Kim, Youngman

    2014-03-01

    The production cross section of neutron-rich isotopes of Ca, Zn, Te, Xe, and Pt are predicted in the diffusive multinucleon transfer reactions with stable and radioactive beams. With these isotopes one can treat the neutron shell evolution beyond N =28, 50, 82, and 126. Because of the small cross sections, the production of nuclei near the neutron drip line requires the optimal choice of reaction partners and bombarding energies.

  6. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator

    NASA Astrophysics Data System (ADS)

    Puchalska, Monika; Sihver, Lembit

    2015-06-01

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18 MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature.

  7. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator.

    PubMed

    Puchalska, Monika; Sihver, Lembit

    2015-06-21

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18 MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature. PMID:26057186

  8. SU-E-T-495: Neutron Induced Electronics Failure Rate Analysis for a Single Room Proton Accelerator

    SciTech Connect

    Knutson, N; DeWees, T; Klein, E

    2014-06-01

    Purpose: To determine the failure rate as a function of neutron dose of the range modulator's servo motor controller system (SMCS) while shielded with Borated Polyethylene (BPE) and unshielded in a single room proton accelerator. Methods: Two experimental setups were constructed using two servo motor controllers and two motors. Each SMCS was then placed 30 cm from the end of the plugged proton accelerator applicator. The motor was then turned on and observed from outside of the vault while being irradiated to known neutron doses determined from bubble detector measurements. Anytime the motor deviated from the programmed motion a failure was recorded along with the delivered dose. The experiment was repeated using 9 cm of BPE shielding surrounding the SMCS. Results: Ten SMCS failures were recorded in each experiment. The dose per monitor unit for the unshielded SMCS was 0.0211 mSv/MU and 0.0144 mSv/MU for the shielded SMCS. The mean dose to produce a failure for the unshielded SMCS was 63.5 ± 58.3 mSv versus 17.0 ±12.2 mSv for the shielded. The mean number of MUs between failures were 2297 ± 1891 MU for the unshielded SMCS and 2122 ± 1523 MU for the shielded. A Wilcoxon Signed Ranked test showed the dose between failures were significantly different (P value = 0.044) while the number of MUs between failures were not (P value = 1.000). Statistical analysis determined a SMCS neutron dose of 5.3 mSv produces a 5% chance of failure. Depending on the workload and location of the SMCS, this failure rate could impede clinical workflow. Conclusion: BPE shielding was shown to not reduce the average failure of the SMCS and relocation of the system outside of the accelerator vault was required to lower the failure rate enough to avoid impeding clinical work flow.

  9. Scintillating glass fiber neutron sensors: 1, Production and optical characterization

    SciTech Connect

    Abel, K.H.; Arthur, R.J.; Bliss, M.

    1993-10-01

    The production and optical characterization of cerium-doped lithium silicate scintillating fibers used as thermal neutron detectors are discussed. The bulk glass continuing enriched {sup 6}Li is produced starting from high-purity commercial materials which are further purified at Pacific Northwest Laboratory (PNL). The fibers are drawn at PNL in a hot down-draw process. The fibers are coated with a silicone polymer that serves as both an optical cladding and a physical buffer coat. Optical characterization has included measurements of light output as a function of glass composition, optical attenuation lengths, and fluorescence lifetimes. Fibers have been prepared in our laboratory with as-drawn attenuation lengths (l/e distance) in excess of 2 meters over sub-meter distances.

  10. Medical Isotope Production With The Accelerator Production of Tritium (APT) Facility

    SciTech Connect

    Buckner, M.; Cappiello, M.; Pitcher, E.; O`Brien, H.

    1998-08-01

    In order to meet US tritium needs to maintain the nuclear weapons deterrent, the Department of Energy (DOE) is pursuing a dual track program to provide a new tritium source. A record of decision is planned for late in 1998 to select either the Accelerator Production of Tritium (APT) or the Commercial Light Water Reactor (CLWR) as the technology for new tritium production in the next century. To support this decision, an APT Project was undertaken to develop an accelerator design capable of producing 3 kg of tritium per year by 2007 (START I requirements). The Los Alamos National Laboratory (LANL) was selected to lead this effort with Burns and Roe Enterprises, Inc. (BREI) / General Atomics (GA) as the prime contractor for design, construction, and commissioning of the facility. If chosen in the downselect, the facility will be built at the Savannah River Site (SRS) and operated by the SRS Maintenance and Operations (M{ampersand}O) contractor, the Westinghouse Savannah River Company (WSRC), with long-term technology support from LANL. These three organizations (LANL, BREI/GA, and WSRC) are working together under the direction of the APT National Project Office which reports directly to the DOE Office of Accelerator Production which has program authority and responsibility for the APT Project.

  11. Neutron generator production mission in a national laboratory.

    SciTech Connect

    Pope, Larry E.

    2007-08-01

    In the late 1980's the Department of Energy (DOE) faced a future budget shortfall. By the spring of 1991, the DOE had decided to manage this problem by closing three production plants and moving production capabilities to other existing DOE sites. As part of these closings, the mission assignment for fabrication of War Reserve (WR) neutron generators (NGs) was transferred from the Pinellas Plant (PP) in Florida to Sandia National Laboratories, New Mexico (SNL/NM). The DOE directive called for the last WR NG to be fabricated at the PP before the end of September 1994 and the first WR NG to be in bonded stores at SNL/NM by October 1999. Sandia National Laboratories successfully managed three significant changes to project scope and schedule and completed their portion of the Reconfiguration Project on time and within budget. The PP was closed in October 1995. War Reserve NGs produced at SNL/NM were in bonded stores by October 1999. The costs of the move were recovered in just less than five years of NG production at SNL/NM, and the annual savings today (in 1995 dollars) is $47 million.

  12. Neutrino, Neutron, and Cosmic-Ray Production in the External Shock Model of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Dermer, Charles D.

    2002-07-01

    The hypothesis that ultrahigh-energy (>~1019 eV) cosmic rays (UHECRs) are accelerated by gamma-ray burst (GRB) blast waves is assumed to be correct. Implications of this assumption are then derived for the external shock model of GRBs. The evolving synchrotron radiation spectrum in GRB blast waves provides target photons for the photomeson production of neutrinos and neutrons. Decay characteristics and radiative efficiencies of the neutral particles that escape from the blast wave are calculated. The diffuse high-energy GRB neutrino background and the distribution of high-energy GRB neutrino events are calculated for specific parameter sets, and a scaling relation for the photomeson production efficiency in surroundings with different densities is derived. GRBs provide an intense flux of high-energy neutrons, with neutron production efficiencies exceeding ~1% of the total energy release. The radiative characteristics of the neutron β-decay electrons from the GRB ``neutron bomb'' are solved in a special case. Galaxies with GRB activity should be surrounded by radiation halos of ~100 kpc extent from the outflowing neutrons, consisting of a nonthermal optical/X-ray synchrotron component and a high-energy gamma-ray component from Compton-scattered microwave background radiation. The peak luminosity emitted by the diffuse β electron halo from a single GRB with >~2×1053 ergs isotropic energy release is ~1035 ergs s-1, with a potentially much brighter signal from the neutron decay protons. The decay halo from a single GRB can persist for >~0.1-1 Myr. Stronger neutrino fluxes and neutron decay halos can be produced by external shocks in clumpy external media and in scenarios involving internal shock scenarios, so detection of neutrinos associated with smooth profile GRBs could rule out an impulsive GRB central engine and an external shock model for the prompt phase. The luminosity of sources of GRBs and relativistic outflows in L* galaxies such as the Milky Way is at

  13. Production of unstable heavy neutrinos in proto-neutron stars

    NASA Astrophysics Data System (ADS)

    Albertus, C.; Masip, M.; Pérez-García, M. A.

    2015-12-01

    We discuss the production of a class of heavy sterile neutrinos νh in proto-neutron stars. The neutrinos, of mass around 50 MeV, have a negligible mixing with the active species but relatively large dimension-5 electromagnetic couplings. In particular, a magnetic dipole moment μ ≈10-6 GeV-1 implies that they are thermally produced through e+e- →νbarhνh in the early phase of the core collapse, whereas a heavy-light transition moment μtr ≈10-8 GeV-1 allows their decay νh →νi γ with a lifetime around 10-3 s. This type of electromagnetic couplings has been recently proposed to explain the excess of electron-like events in baseline experiments. We show that the production and decay of these heavy neutrinos would transport energy from the central regions of the star to distances d ≈ 400 km, providing a very efficient mechanism to enhance the supernova shock front and heat the material behind it.

  14. Thermal neutron fluence in a treatment room with a Varian linear accelerator at a medical university hospital

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Shan; Changlai, Sheng-Pin; Pan, Lung-Kwang; Tseng, Hsien-Chun; Chen, Chien-Yi

    2011-09-01

    The indium foil activation technique has been employed to measure thermal neutron fluences ( Φth) among various locations in the treatment room with a 20×20 cm 2 field size and a 15 and 10 MV X-ray beam. Spatial Φth are visualized using colored three-dimensional graphical representations; intensities are up to (1.97±0.13)×10 5 and (1.46±0.13)×10 4 n cm -2/Gy-X at isocenter, respectively. The Φth is found to increase with the X-ray energy of the LINAC and decreases as it moves away from the beam center. However, thermal neutron exposure is not assessed in routine dosimetry planning and radiation assessment of patients since neutron dose contributes <1% of the given therapy dose. However, unlike the accelerated beam limited within the gantry window, photoneutrons are widely spread in the treatment room. Distributions of Φth were measured in water phantom irradiated with 15 MV X-ray beams. The shielding effect of the maze was also evaluated. The experimentally estimated Φth along the maze distance was fitted explicate and the tenth-value layer (TVL) was calculated and discussed. Use of a 10 cm-thick polyethylene door placed at the maze was suitable for radiation shielding.

  15. RADIATION PROTECTION SYSTEM INSTALLATION FOR THE ACCELERATOR PRODUCTION OF TRITIUM/LOW ENERGY DEMONSTRATION ACCELERATOR PROJECT (APT/LEDA)

    SciTech Connect

    J. WILMARTH; M. SMITH; T. TOMEI

    1999-07-01

    The APT/LEDA personnel radiation protection system installation was accomplished using a flexible, modular proven system which satisfied regulatory orders, project design criteria, operational modes, and facility requirements. The goal of providing exclusion and safe access of personnel to areas where prompt radiation in the LEDA facility is produced was achieved with the installation of a DOE-approved Personnel Access Control System (PACS). To satisfy the facility configuration design, the PACS, a major component of the overall radiation safety system, conveniently provided five independent areas of personnel access control. Because of its flexibility and adaptability the Los Alamos Neutron Science Center (LANSCE) designed Radiation Security System (RSS) was efficiently configured to provide the desired operational modes and satisfy the APT/LEDA project design criteria. The Backbone Beam Enable (BBE) system based on the LANSCE RSS provided the accelerator beam control functions with redundant, hardwired, tamper-resistant hardware. The installation was accomplished using modular components.

  16. Neutron production from flattening filter free high energy medical linac: A Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Najem, M. A.; Abolaban, F. A.; Podolyák, Z.; Spyrou, N. M.

    2015-11-01

    One of the problems arising from using a conventional linac at high energy (>8 MV) is the production of neutrons. One way to reduce neutron production is to remove the flattening filter (FF). The main purpose of this work was to study the effect of FF removal on neutron fluence and neutron dose equivalent inside the treatment room at different photon beam energies. Several simulations based on Monte Carlo techniques were carried out in order to calculate the neutron fluence at different locations in the treatment room from different linac energies with and without a FF. In addition, a step-and-shoot intensity modulated radiotherapy (SnS IMRT) for prostate cancer was modelled using the 15 MV photon beam with and without a FF on a water phantom to calculate the neutron dose received in a full treatment. The results obtained show a significant drop-off in neutrons fluence and dose equivalent when the FF was removed. For example, the neutron fluence was decreased by 54%, 76% and 75% for 10, 15 and 18 MV, respectively. This can decrease the neutron dose to the patient as well as reduce the shielding cost of the treatment room. The neutron dose equivalent of the SnS IMRT for prostate cancer was reduced significantly by 71.3% when the FF was removed. It can be concluded that the flattening filter removal from the head of the linac could reduce the risk of causing secondary cancers and the shielding cost of radiotherapy treatment rooms.

  17. Accelerator measurement of the energy spectra of neutrons emitted in the interaction of 3-GeV protons with several elements

    NASA Technical Reports Server (NTRS)

    Nalesnik, W. J.; Devlin, T. J.; Merker, M.; Shen, B. S. P.

    1972-01-01

    The application of time of flight techniques for determining the shapes of the energy spectra of neutrons between 20 and 400 MeV is discussed. The neutrons are emitted at 20, 34, and 90 degrees in the bombardment of targets by 3 GeV protons. The targets used are carbon, aluminum, cobalt, and platinum with cylindrical cross section. Targets being bombarded are located in the internal circulating beam of a particle accelerator.

  18. Thermal analysis and neutron production characteristics of a low power copper beam dump-cum-target for LEHIPA

    NASA Astrophysics Data System (ADS)

    Sawant, Y. S.; Thomas, R. G.; Verma, V.; Agarwal, A.; Prasad, N. K.; Bhagwat, P. V.; Saxena, A.; Singh, P.

    2016-01-01

    Monte Carlo simulations of heat deposition and neutron production have been carried out for the low power beam dump-cum-target for the 20 MeV Low Energy High Intensity Proton Accelerator (LEHIPA) facility at BARC using GEANT4 and FLUKA. Thermal analysis and heat transfer calculations have also been carried out using the computational fluid dynamics code CFD ACE+. In this work we present the details of the analysis of the low power beam dump-cum-target designed for conditioning of the accelerator upto a maximum power of 600 kW with a duty cycle of 2% which corresponds to an average power of 12 kW in the first phase.

  19. A study on the utilization of tritide titanium targets for monoenergetic neutron production

    NASA Astrophysics Data System (ADS)

    Karamanis, D.

    2002-10-01

    Proton beam interaction with a tritide titanium target in an electrostatic accelerator was studied by measuring the produced neutron rate as a function of bombarding time. The results are analyzed in the frame of target temperature increase, extension of existing low energy interaction model and SRIM simulation. Special emphasis is put on the evaluation of the release of radiotoxic tritium from the solid target.

  20. Exclusive vector meson production with a leading neutron in photon-hadron interactions at hadronic colliders

    NASA Astrophysics Data System (ADS)

    Gonçalves, V. P.; Moreira, B. D.; Navarra, F. S.; Spiering, D.

    2016-07-01

    In this paper, we study leading neutron production in photon-hadron interactions that take place in p p and p A collisions at large impact parameters. Using a model that describes the recent leading neutron data at HERA, we consider exclusive vector meson production in association with a leading neutron in p p /p A collisions at RHIC and LHC energies. The total cross sections and rapidity distributions of ρ , ϕ , and J /Ψ produced together with a leading neutron are computed. Our results indicate that the study of these processes is feasible and that it can be used to improve the understanding of leading neutron processes and of exclusive vector meson production.

  1. Radioxenon production through neutron irradiation of stable xenon gas

    SciTech Connect

    Haas, Derek A.; Biegalski, Steven R.; Foltz Biegalski, Kendra M.

    2009-12-01

    The Spectral Deconvolution Analysis Tool (SDAT) software was developed to improve counting statistics and detection limits for nuclear explosion radionuclide measurements. SDAT utilizes spectral deconvolution spectroscopy techniques and can analyze both β-γ coincidence spectra for radioxenon isotopes and high-resolution HPGe spectra from aerosol monitors. The deconvolution algorithm of the SDAT requires a library of β-γ coincidence spectra of individual radioxenon isotopes to determine isotopic ratios in a sample. In order to get experimentally produced spectra of the individual isotopes we have irradiated enriched samples of 130Xe, 132Xe, and 134Xe gas with a neutron beam from the TRIGA reactor at The University of Texas. The samples produced were counted in an Automated Radioxenon Sampler/Analyzer (ARSA) style β-γ coincidence detector. The spectra produced show that this method of radioxenon production yields samples with very high purity of the individual isotopes for 131mXe and 135Xe and a sample with a substantial 133mXe to 133Xe ratio.

  2. {sup 233}U breeding measurements in a thorium-oxide blanket assembly using A (d,t) accelerator neutron source

    SciTech Connect

    Anand, R.P.; Basu, T.K.; Ramakrishna, D.V.S.

    1997-05-01

    Uranium-233 breeding studies are carried out in a compact thorium-oxide cylindrical blanket assembly surrounded by a thick polypropylene reflector in a fusion neutron environment. The assembly consists of 11 rings of thorium-oxide rods stacked in a hexagonal geometry with a central through channel for the 14-MeV (d,t) neutron source. A total of 120 thorium-oxide probes are inserted inside the rods in different axial and radial locations in the assembly, which is then subjected to 14-MeV neutron irradiation for 25 h. Protactinium-233 gamma activity produced in the probes because of neutron captures in the thorium is measured using a high-efficiency, high-purity germanium detector. The measured {sup 233}U production rates are fitted to obtain axial and radial distributions for different rings. These distributions are used to obtain the total {sup 233}U breeding in the whole assembly. The integral measured values are found to be in good agreement with the calculated values obtained employing the MCNP Monte Carlo code using the BMCCS2 cross-section library. 8 refs., 4 figs., 5 tabs.

  3. Kinetic simulation of neutron production in a deuterium z-pinch.

    SciTech Connect

    Mostrom, C.; Stygar, William A.; Thoma, Carsten; Welch, Dale Robert; Clark, R. E.; Leeper, Ramon Joe; Rose, David V.

    2010-11-01

    We have found computationally that, at sufficiently high currents, half of the neutrons produced by a deuterium z pinch are thermonuclear in origin. Early experiments below 1-MA current found that essentially all of the neutrons produced by a deuterium pinch are not thermonuclear, but are initiated by an instability that creates beam-target neutrons. Many subsequent authors have supported this result while others have claimed that pinch neutrons are thermonuclear. To resolve this issue, we have conducted fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium pinch. We find that at 1-MA pinch currents, most of the neutrons are, indeed, beam-target in origin. At much higher current, half of the neutrons are thermonuclear and half are beam-target driven by instabilities that produce a power law fall off in the ion energy distribution function at large energy. The implications for fusion energy production with such pinches are discussed.

  4. Monochromatic neutron beam production at Brazilian nuclear research reactors

    NASA Astrophysics Data System (ADS)

    Stasiulevicius, Roberto; Rodrigues, Claudio; Parente, Carlos B. R.; Voi, Dante L.; Rogers, John D.

    2000-12-01

    Monochomatic beams of neutrons are obtained form a nuclear reactor polychromatic beam by the diffraction process, suing a single crystal energy selector. In Brazil, two nuclear research reactors, the swimming pool model IEA-R1 and the Argonaut type IEN-R1 have been used to carry out measurements with this technique. Neutron spectra have been measured using crystal spectrometers installed on the main beam lines of each reactor. The performance of conventional- artificial and natural selected crystals has been verified by the multipurpose neutron diffractometers installed at IEA-R1 and simple crystal spectrometer in operator at IEN- R1. A practical figure of merit formula was introduced to evaluate the performance and relative reflectivity of the selected planes of a single crystal. The total of 16 natural crystals were selected for use in the neutron monochromator, including a total of 24 families of planes. Twelve of these natural crystal types and respective best family of planes were measured directly with the multipurpose neutron diffractometers. The neutron spectrometer installed at IEN- R1 was used to confirm test results of the better specimens. The usually conventional-artificial crystal spacing distance range is limited to 3.4 angstrom. The interplane distance range has now been increased to approximately 10 angstrom by use of naturally occurring crystals. The neutron diffraction technique with conventional and natural crystals for energy selection and filtering can be utilized to obtain monochromatic sub and thermal neutrons with energies in the range of 0.001 to 10 eV. The thermal neutron is considered a good tool or probe for general applications in various fields, such as condensed matter, chemistry, biology, industrial applications and others.

  5. RAMI modeling of selected balance of plant systems for the proposed Accelerator Production of Tritium (APT) project

    SciTech Connect

    Radder, J.A.; Cramer, D.S.

    1997-06-01

    In order to meet Department of Energy (DOE) Defense Program requirements for tritium in the 2005-2007 time frame, new production capability must be made available. The Accelerator Production of Tritium (APT) Plant is being considered as an alternative to nuclear reactor production of tritium, which has been the preferred method in the past. The proposed APT plant will use a high-power proton accelerator to generate thermal neutrons that will be captured in {sup 3}He to produce tritium (3H). It is expected that the APT Plant will be built and operated at the DOE`s Savannah River Site (SRS) in Aiken, South Carolina. Discussion is focused on Reliability, Availability, Maintainability, and Inspectability (RAMI) modeling of recent conceptual designs for balance of plant (BOP) systems in the proposed APT Plant. In the conceptual designs for balance of plant (BOP) systems in the proposed APT Plant. In the conceptual design phase, system RAMI estimates are necessary to identify the best possible system alternative and to provide a valid picture of the cost effectiveness of the proposed system for comparison with other system alternatives. RAMI estimates in the phase must necessarily be based on generic data. The objective of the RAMI analyses at the conceptual design stage is to assist the designers in achieving an optimum design which balances the reliability and maintainability requirements among the subsystems and components.

  6. Laser induced neutron production by explosion of the deuterium clusters

    NASA Astrophysics Data System (ADS)

    Holkundkar, Amol R.; Mishra, Gaurav; Gupta, N. K.

    2014-01-01

    The high energy deuterium ions serve as compact source of neutrons when fused with either deuterium or tritium atoms. In view of this, the explosion of the deuterium clusters under the influence of the laser pulse with intensity ranging from 1015 to 1019 W/cm2 is being studied along with the effect of the cluster radius and inter-cluster distance. The objective of this article is to study the efficiency of the deuterium cluster as a compact source of neutrons under various laser and cluster parameters. It is being observed that the cluster density (number of clusters per unit volume) is quite important to gain high neutron yield.

  7. Connecting inflation with late cosmic acceleration by particle production

    NASA Astrophysics Data System (ADS)

    Nunes, Rafael C.

    2016-04-01

    A continuous process of creation of particles is investigated as a possible connection between the inflationary stage with late cosmic acceleration. In this model, the inflationary era occurs due to a continuous and fast process of creation of relativistic particles, and the recent accelerating phase is driven by the nonrelativistic matter creation from the gravitational field acting on the quantum vacuum, which finally results in an effective equation of state (EoS) less than ‑ 1. Thus, explaining recent results in favor of a phantom dynamics without the need of any modifications in the gravity theory has been proposed. Finally, we confront the model with recent observational data of type Ia Supernova, history of the Hubble parameter, baryon acoustic oscillations (BAOs) and the cosmic microwave background (CMB).

  8. Activation caused by proton beam losses in Accelerator Production of Tritium LINAC

    SciTech Connect

    Beard, C.A.; Eaton, S.L.; Daemen, L.L.; Waters, L.S.; Wilson, W.B.

    1996-03-01

    A variety of accelerator designs are being considered for the Accelerator Production of Tritium (APT) project at Alamos National Laboratory. Because activation of the structural components of the accelerator is considered a major radiation protection issue, we have developed a computational methodology to estimate quantitatively radionuclide inventories and gamma dose rates resulting from accelerator operation. The work presented here illustrates the use of our computational methodology by focusing on the 20 and 100 MeV sections of the Bridge-Coupled Drift Tube LINAC (BCDTL), and the 100 and 1000 MeV sections of the Coupled Cavity LINAC (CCL).

  9. Generation of fast neutrons through deuteron acceleration at the PALS laser facility

    NASA Astrophysics Data System (ADS)

    Krása, J.; Klír, D.; Velyhan, A.; Řezáč, K.; Cikhardt, J.; Ryć, L.; Krouský, E.; Pfeifer, M.; De Marco, M.; Skála, J.; Dudžák, R.; Ullschmied, J.

    2016-03-01

    Recent experiments at the laser facility PALS focused on the laser driven fusion of deuterons are reviewed. They benefit of high reaction cross-sections and of a high number of multi-MeV deuterons from thick CD2 targets irradiated by intensity of 3× 1016 W cm-2. In the reported experiments fast fusion neutrons with energy up to 16 MeV were produced through 7Li(d, n)8Be and 11B(d, n)12C reactions in a pitcher-catcher target configuration. When using a large area CD2 foil as a secondary catcher target the total maximum neutron yield from the 2H(d, n)3He reaction increased by a factor of about 5, from 4× 108 to 2× 109. This result reveals that most of the deuterons having enough kinetic energy to enter a fusion reaction are emitted from the primary target into vacuum.

  10. Abrasion-ablation model for neutron production in heavy ion reactions

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Wilson, John W.; Townsend, Lawrence W.

    1995-01-01

    In heavy ion reactions, neutron production at forward angles is observed to occur with a Gaussian shape that is centered near the beam energy and extends to energies well above that of the beam. This paper presents an abrasion-ablation model for making quantitative predictions of the neutron spectrum. To describe neutrons produced from the abrasion step of the reaction where the projectile and target overlap, the authors use the Glauber model and include effects of final-state interactions. They then use the prefragment mass distribution from abrasion with a statistical evaporation model to estimate the neutron spectrum resulting from ablation. Measurements of neutron production from Ne and Nb beams are compared with calculations, and good agreement is found.

  11. Neutron Production Measurements Relevant to Shielding forSpace-Related Activities

    SciTech Connect

    Heilbronn, Lawrence; Iwata, Yoshiyuki; Murakami, Takeshi; Iwase,Hiroshi; Nakamura, Takashi; Sato, Hisaki; Ronningen, Reginald

    2002-04-09

    Neutron production cross sections have been measured from290 MeV/nucleon C and 600 MeV/nucleon Ne interacting in a slab ofsimulated Martian regolith/polyethylene composite, and from 400MeV/nucleon Ne interacting in a section of wall materials from theInternational Space Station. Neutron spectra were measured at 7 anglesbetween 5 degrees and 80 degrees, and for neutron energies 5 MeV andgreater. Spectra at forward angles are dominated by the breakup of theprojectile, whereas spectra at back angles show the typical exponentialfalloff with energy that is indicative of decay from the overlap regionand the target remnant. The measured total neutron production crosssections indicate that the regolith/polyethylene composite may be a moreeffective shielding material than the ISS wall materials, in terms of thenumber of neutrons produced.

  12. Beta-Delayed Neutron Spectroscopy with Trapped Fission Products

    NASA Astrophysics Data System (ADS)

    Czeszumska, A.; Scielzo, N. D.; Norman, E. B.; Savard, G.; Aprahamian, A.; Burkey, M.; Caldwell, S. A.; Chiara, C. J.; Clark, J. A.; Harker, J.; Marley, S. T.; Morgan, G.; Orford, R.; Padgett, S.; Perez Galvan, A.; Segel, R. E.; Sharma, K. S.; Siegl, K.; Strauss, S.; Yee, R. M.

    2014-09-01

    Characterizing β-delayed neutron emission (βn) is of importance in reactor safety modeling, understanding of r-process nucleosynthesis, and nuclear structure studies. A newly developed technique enables a reliable measurement of βn branching ratios and neutron energy spectra without directly detecting neutrons. Ions of interest are loaded into a Paul trap surrounded by an array of radiation detectors. Upon decay, recoiling daughter nuclei and emitted particles emerge from the center of the trap with minimal scattering. The neutron energy is then determined from the time-of-flight, and hence momentum, of the recoiling ions. I will explain the details of the technique, and present the results from the most recent experimental campaign at the CARIBU facility at Argonne National Laboratory. Characterizing β-delayed neutron emission (βn) is of importance in reactor safety modeling, understanding of r-process nucleosynthesis, and nuclear structure studies. A newly developed technique enables a reliable measurement of βn branching ratios and neutron energy spectra without directly detecting neutrons. Ions of interest are loaded into a Paul trap surrounded by an array of radiation detectors. Upon decay, recoiling daughter nuclei and emitted particles emerge from the center of the trap with minimal scattering. The neutron energy is then determined from the time-of-flight, and hence momentum, of the recoiling ions. I will explain the details of the technique, and present the results from the most recent experimental campaign at the CARIBU facility at Argonne National Laboratory. This work was supported under contracts DE-NA0000979 (NSSC), DE-AC52-07NA27344 (LLNL), DE-AC02-06CH11357 (ANL), DE-FG02-94ER40834 (U. Maryland), DE-FG02-98ER41086 (Northwestern U.), NSERC, Canada, under Application No. 216974, and DHS.

  13. Neutron sources: present practice and future potential

    SciTech Connect

    Cierjacks, S.; Smith, A.B.

    1988-01-01

    The present capability and future potential of accelerator-based monoenergetic and white neutron sources are outlined in the context of fundamental and applied neutron-nuclear research. The neutron energy range extends from thermal to 500+ MeV, and the time domain from steady-state to pico-second pulsed sources. Accelerator technology is summarized, including the production of intense light-ion, heavy-ion and electron beams. Target capabilities are discussed with attention to neutron-production efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: (i) fundamental neutron-nuclear research, (ii) nuclear-data acquisition, (iii) materials-damage studies, (iv) engineering test, and (v) biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections.

  14. Neutron induced pion production on C, Al, Cu, and W at neutron energies of 200--600 MeV

    SciTech Connect

    Brooks, M.L.

    1991-10-01

    Inclusive double differential neutron induced {pi}{sup +} and {pi}{sup {minus}} production cross sections were measured for four separate targets: C, Al, Cu and W. The neutron energy range was 200--600 MeV and the pion angular range was 25{degrees}--125{degrees}. The charge, scattering angle and energy of the pions were measured using a magnetic spectrometer. The measurements are compared with intranuclear cascade (INC) calculations and a previous experiment that measured the sum of the {pi}{sup +} and {pi}{sup {minus}} cross sections. Our data agree with the measured data, but the INC calculations give only moderate agreement with the double differential cross sections as well as with angular distributions and total cross sections as a function of neutron energy. The ratio of {pi}{sup {minus}}:{pi}{sup +} was found to increase rapidly with decreasing neutron energy and the pion production was found to increase approximately as A{sup 2/3} for the different targets. 31 refs., 55 figs., 6 tabs.

  15. Shielding design of a treatment room for an accelerator-based epithermal neutron irradiation facility for BNCT.

    PubMed

    Evans, J F; Blue, T E

    1996-11-01

    Protecting the facility personnel and the general public from radiation exposure is a primary safety concern of an accelerator-based epithermal neutron irradiation facility. This work makes an attempt at answering the questions "How much?" and "What kind?" of shielding will meet the occupational limits of such a facility. Shielding effectiveness is compared for ordinary and barytes concretes in combination with and without borated polyethylene. A calculational model was developed of a treatment room , patient "scatterer," and the epithermal neutron beam. The Monte Carlo code, MCNP, was used to compute the total effective dose equivalent rates at specific points of interest outside of the treatment room. A conservative occupational effective dose rate limit of 0.01 mSv h-1 was the guideline for this study. Conservative Monte Carlo calculations show that constructing the treatment room walls with 1.5 m of ordinary concrete, 1.2 m of barytes concrete, 1.0 m of ordinary concrete preceded by 10 cm of 5% boron-polyethylene, or 0.8 m of barytes concrete preceded by 10 cm of 5% boron-polyethylene will adequately protect facility personnel. PMID:8887513

  16. Shielding design of a treatment room for an accelerator-based epithermal neutron irradiation facility for BNCT

    SciTech Connect

    Evans, J.F.; Blue, T.E.

    1996-11-01

    Protecting the facility personnel and the general public from radiation exposure is a primary safety concern of an accelerator-based epithermal neutron irradiation facility. This work makes an attempt at answering the questions {open_quotes}How much?{close_quotes} and {open_quotes}What kind?{close_quotes} of shielding will meet the occupational limits of such a facility. Shielding effectiveness is compared for ordinary and barytes concretes in combination with and without borated polyethylene. A calculational model was developed of a treatment room, patient {open_quotes}scatterer,{close_quotes} and the epithermal neutron beam. The Monte Carlo code, MCNP, was used to compute the total effective dose equivalent rates at specific points of interest outside of the treatment room. A conservative occupational effective dose rate limit of 0.01 mSv h{sup {minus}1} was the guideline for this study. Conservative Monte Carlo calculations show that constructing the treatment room walls with 1.5 m of ordinary concrete, 1.2 m of barytes concrete, 1.0 m of ordinary concrete preceded by 10 cm of 5% boron-polyethylene, or 0.8 m of barytes concrete preceded by 10 cm of 5% boron-polyethylene will adequately protect facility personnel. 20 refs., 8 figs., 2 tabs.

  17. An accelerator-based epithermal photoneutron source for BNCT

    SciTech Connect

    Nigg, D.W.; Mitchell, H.E.; Harker, Y.D.; Yoon, W.Y.

    1995-11-01

    Therapeutically-useful epithermal-neutron beams for BNCT are currently generated by nuclear reactors. Various accelerator-based neutron sources for BNCT have been proposed and some low intensity prototypes of such sources, generally featuring the use of proton beams and beryllium or lithium targets have been constructed. This paper describes an alternate approach to the realization of a clinically useful accelerator-based source of epithermal neutrons for BNCT that reconciles the often conflicting objectives of target cooling, neutron beam intensity, and neutron beam spectral purity via a two stage photoneutron production process.

  18. Upgrade of the IGN-14 neutron generator for research on detection of fusion-plasma products

    NASA Astrophysics Data System (ADS)

    Igielski, Andrzej; Kurowski, Arkadiusz; Janik, Władysław; Gabańska, Barbara; Woźnicka, Urszula

    2015-10-01

    The fast neutron generator (IGN-14) at the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Kraków (Poland) is a laboratory multi-purpose experimental device. Neutrons are produced in a beam-target D-D or D-T reactions. A new vacuum chamber installed directly to the end of the ion guide of IGN-14 makes it possible to measure not only neutrons but also alpha particles in the presence of a mixed radiation field of other accompanying reaction products. The new experimental setup allows test detectors dedicated to spectrometric measurements of thermonuclear fusion reaction products.

  19. Development of the accelerator-driven energy production concept

    SciTech Connect

    Venneri, F.; Beard, C.; Bowman, C.

    1996-10-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Accelerator Driven Transmutation Technology (ADTT) offers a means of generating nuclear energy in a clean, safe way that can be attractive to the general public. However, there are issues associated with the energy story (both at the system level and technical detail) that have to be seriously addressed before the scientific community, the public, and potential industrial sponsors can be compellingly convinced of its cost/benefit.

  20. Spiked Alloy Production for Accelerated Aging of Plutonium

    SciTech Connect

    Wilk, P A; McNeese, J A; Dodson, K E; Williams, W L; Krikorian, O H; Blau, M S; Schmitz, J E; Bajao, F G; Mew, D A; Matz, T E; Torres, R A; Holck, D M; Moody, K J; Kenneally, J M

    2009-07-10

    The accelerated aging effects on weapons grade plutonium alloys are being studied using {sup 238}Pu-enriched plutonium metal to increase the rate of formation of defect structures. Pyrochemical processing methods have been used to produce two {sup 238}Pu-spiked plutonium alloys with nominal compositions of 7.5 wt% {sup 238}Pu. Processes used in the preparation of the alloys include direct oxide reduction of PuO{sub 2} with calcium and electrorefining. Rolled disks were prepared from the spiked alloys for sampling. Test specimens were cut out of the disks for physical property measurements.

  1. Experimental study on anomalous neutron production in deuterium/solid system

    NASA Astrophysics Data System (ADS)

    He Jianyu, Zhu Rongbao, Wang Xiaozhong, Lu Feng, Luo Longjun, Liu Hengjun, Jiang Jincai, Tian Baosheng, Chen Guoan, Yuan Yuan, Dong Baiting, Yang Liucheng, Qiao Shengzhong, Yi Guoan, Guo Hua, Ding Dazhao, Menlove, H. O.

    1991-05-01

    A series of experiments on both D2O electrolysis and thermal cycle of deuterium absorbed Ti Turnings has been designed to examine the anomalous phenomena in Deuterium/Solid System. A neutron detector containing 16 BF3 tubes with a detection limit of 0.38 n/s for two hour counting was used for electrolysis experiments. No neutron counting rate statistically higher than detection limit was observed from Fleischmann & Pons type experiments. An HLNCC neutron detector equipped with 18 3He tubes and a JSR-11 shift register unit with a detection limit of 0.20 n/s for a two hour run was employed to study the neutron signals in D2 gas experiments. Different material pretreatments were selected to review the changes in frequency and size of the neutron burst production. Experiment sequence was deliberately designed to distinguish the neutron burst from fake signals, e.g. electronic noise pickup, the cosmic rays and other sources of environmental background. Ten batches of dry fusion samples were tested, among them, seven batches with neutron burst signals occurred roughly at the temperature from -100 degree centigrade to near room temperature. In the first four runs of a typical sample batch, seven neutron bursts were observed with neutron numbers from 15 to 482, which are 3 and 75 times, respectively, higher than the uncertainty of background. However, no bursts happened for H2 dummy samples running in-between and afterwards and for sample batch after certain runs.

  2. Production of the SIGMA(0)(C) and SIGMA(++)(C) by High Energy Neutrons.

    NASA Astrophysics Data System (ADS)

    Ladbury, Raymond Llewellyn, Jr.

    We present the first observation of hadroproduction of the Sigma_sp{c}{++ } and Sigma_sp{c }{0}, decaying into Lambda _{c}pi. The daughter Lambda_{c} is observed in the decay modes pKpi and pK _{s}pipi. The Experiment was conducted at a broadband neutron beam in the Proton East area of the Fermi National Accelerator Laboratory. A two-magnet multiparticle spectrometer equipped with proportional wire chambers and a high resolution MWPC vertex detector was used to momentum analyze charged particles produced in the interactions of neutrons on targets of beryllium, silicon and tungsten. Particles were identified using three Cerenkov counters. The beam energy for each event was reconstructed using hadronic and electromagnetic calorimetry. The mass differences delta m_ {Sigma_sp{c}{++}- Lambda_{c}}, delta m_{Sigma_sp{c }{0}-Lambda_{c}} and delta m_{Sigma _sp{c}{++}-Sigma_sp {c}{0}} are measured and found to be 166.4 +/-.3 +/- 2.0 MeV/c^2, 178.5 +/-.3 +/- 2.5MeV/c ^2 and -12.1 +/- .4 +/- 2.8MeV/c^2 . This last value is larger in magnitude than the predictions of most theoretical calculations. We also report measurements of particle to antiparticle ratios, x_{f} dependence, A dependence, and p_{t} dependence of the production cross sections. The total production cross sections of the Sigma_sp{c} {0} and Sigma_sp {c}{++} are calculated, assuming {dsigmaover dx_{f }} ~ (1 -x)^4, linear atomic weight dependence, B(Lambda_{c} to pKpi) =.022, and symmetric production of particle and antiparticle. From this, and the value of sigma cdot B( Lambda_{c} to pK_sp{s}{0} pipi), calculated under the same assumptions, we calculate the ratio of branching fractions {B(Lambda_{c} to p| K^{0}pipi)}over {B(Lambda_{c}to pKpi) }. We conclude that the level of charm production indicated by our measurements is substantially higher than that predicted by first order gluon-gluon fusion.

  3. Modification of a pulsed 14-MeV fast neutron generator to a medium-energy ion accelerator for TOF-RBS application

    NASA Astrophysics Data System (ADS)

    Junphong, P.; Suwannakachorn, D.; Yu, L. D.; Singkarat, S.

    2011-12-01

    The first drift-tube neutron generator in Thailand, developed during 1980s under the support by the International Atomic Energy Agency (IAEA), was a 150 kV deuteron accelerator-based 14 MeV fast neutron generator. The accelerator was featured by a nanosecond pulsing system consisting of a beam chopper in combination with a beam buncher. Following the rapid development of ion beam technology and increasing needs for materials applications in the laboratory, the accelerator has been upgraded and modified to a large extent into a medium-energy ion-accelerator for time-of-flight Rutherford backscattering spectrometry (TOF-RBS) applications. The modification of the accelerator included the changing of the ion source, the accelerating tube and the mass-analyzing magnet, the upgrading of the pulsing system, and the installation of a TOF-RBS detecting system. The new accelerator is capable of supplying a 400-keV He-ion beam with ns-pulses for nano-layered materials analysis. This paper provides technical details of the modification.

  4. Laser-driven high-energy-density deuterium and tritium ions for neutron production in a double-cone configuration

    NASA Astrophysics Data System (ADS)

    Hu, Li-Xiang; Yu, Tong-Pu; Shao, Fu-Qiu; Zhu, Qing-Jun; Yin, Yan; Ma, Yan-Yun

    2015-12-01

    By using two-dimensional particle-in-cell simulations, we investigate laser-driven ion acceleration and compression from a thin DT foil in a double-cone configuration. By using two counterpropagating laser pulses, it is shown that a double-cone structure can effectively guide, focus, and strengthen the incident laser pulses, resulting in the enhanced acceleration and compression of D+ and T+. Due to the ion Coulomb repulsion and the effective screening from the external laser electric fields, the transverse diffusion of ions is significantly suppressed. Finally, the peak energy density of the compressed ions exceeds 2.73 × 1016 J/m3, which is about five orders of magnitude higher than the threshold for high energy density physics, 1011 J/m3. Under this condition, DT fusion reactions are initiated and the neutron production rate per volume is estimated to be as high as 7.473 × 1035/m3 s according to Monte Carlo simulations. It is much higher than that of the traditional large neutron sources, which may facilitate many potential applications.

  5. Laser-driven high-energy-density deuterium and tritium ions for neutron production in a double-cone configuration

    SciTech Connect

    Hu, Li-Xiang; Yu, Tong-Pu Shao, Fu-Qiu; Yin, Yan; Ma, Yan-Yun; Zhu, Qing-Jun

    2015-12-15

    By using two-dimensional particle-in-cell simulations, we investigate laser-driven ion acceleration and compression from a thin DT foil in a double-cone configuration. By using two counterpropagating laser pulses, it is shown that a double-cone structure can effectively guide, focus, and strengthen the incident laser pulses, resulting in the enhanced acceleration and compression of D{sup +} and T{sup +}. Due to the ion Coulomb repulsion and the effective screening from the external laser electric fields, the transverse diffusion of ions is significantly suppressed. Finally, the peak energy density of the compressed ions exceeds 2.73 × 10{sup 16 }J/m{sup 3}, which is about five orders of magnitude higher than the threshold for high energy density physics, 10{sup 11 }J/m{sup 3}. Under this condition, DT fusion reactions are initiated and the neutron production rate per volume is estimated to be as high as 7.473 × 10{sup 35}/m{sup 3} s according to Monte Carlo simulations. It is much higher than that of the traditional large neutron sources, which may facilitate many potential applications.

  6. Improving Epithermal Transmission Measurements by Optimizing Neutron Production and Detection

    NASA Astrophysics Data System (ADS)

    Piela, Sean Garrigan

    Methods of improving the neutron count rate in the energy range 3 to 100-300 [keV] at the 100 [m] detector station for the Gaerttner LINAC Center were studied. One part of this undertaking was the explore alterations to the main photonuclear target used for this energy range. Detailed simulations using Monte Carlo N-Particle Transport Code (MCNP, version 5) were carried out and the results used to synthesize an optimized target design. Simulation predicted a gain in neutron intensity of 1.63 at 4.49 [keV], above the current target capability. Experiment found a gain of 1.42 at 4.89 [keV] over the current target. An addition of 1% boric acid to the water in the moderating ring of the current target is predicted to result in a factor of 111 +/- 12 increase in the neutron to photon ratio above baseline for 3.51 [keV] neutrons at 100 [m]; this value is for photons above 700 [keV]. The gain in neutron intensity for the optimized target comes with a gain in photon intensity. A 1% boric acid addition to this design has same neutron to photon ratio as with the boric acid addition to the current target (for 3.51 [keV] neutrons). In an alternate approach to enhancing the neutron counts, a prototype plastic scintillator was studied as a possible replacement for the extant lithium glass scintillators, with experiments finding major increases to the neutron counts in the energy range of interest. The plastic scintillator prototype was found to produce gains of 1.86, 3.61, 1.76 and 3.16 at 70.1, 127, 219, and 307 [keV], respectively, over a lithium glass detector. However, at 24.5 [keV] the plastic prototype count rate was only 36% of that measured with the lithium glass detector. The prototype detector geometry and its associated electronics need to be altered in order to actualize the true potential of the plastic scintillator detector.

  7. Calculations of helium production in materials irradiated at spallation neutron sources

    SciTech Connect

    Corzine, R.K.; Dudziak, D.J.; Wechsler, M.S.; Barnett, M.H.; Mansur, L.K.

    1998-09-01

    Experience with materials irradiated in fission reactor neutron environments has shown that radiation-produced helium can exacerbate the degradation of properties caused by radiation-produced defects and defect clusters. Whereas fission-reactor neutron energies extend up to {approximately}10 MeV, the neutrons and protons at spallation neutron sources reach up to 1,000 to 2,000 MeV, and He production is much greater. For example, calculations have shown for the innermost shell of the containment vessel of the spallation neutron source, under collaborative design by several national laboratories led by the Oak Ridge National Laboratory, that full-power displacement and He production rates are {approximately}20 displacements per atom (dpa)/yr and 1,000 atomic parts per million (appm) He/yr, which corresponds to 50 appm He/dpa. By contrast, materials in fission reactor cores usually experience <1 appm He/dpa. In this paper, the authors summarize methods and results for the calculation of He production cross sections appropriate to the neutron and proton energies to which target and containment materials are exposed at spallation neutron sources. The principal calculational tool is LAHET or, more broadly, the LAHET code system (LCS).

  8. Development of an accelerator based system for in vivo neutron activation analysis measurements of manganese in humans

    NASA Astrophysics Data System (ADS)

    Arnold, Michelle Lynn

    2001-11-01

    Manganese is required by the human body, but as with many heavy elements, in large amounts it can be toxic, producing a neurological disorder similar to that of Parkinson's Disease. The primary industrial uses of the element are for the manufacturing of steel and alkali batteries. Environmental exposure may occur via drinking water or exhaust emissions from vehicles using gasoline with the manganese containing compound MMT as an antiknock agent (MMT has been approved for use in both Canada and the United States). Preclinical symptoms of toxicity have recently been detected in individuals occupationally exposed to airborne manganese at levels below the present threshold limit value set by the EPA. Evidence also suggests that early detection of manganese toxicity is crucial since once the symptoms have developed past a certain point, the syndrome will continue to progress even if manganese exposure ceases. The development of a system for in vivo neutron activation analysis (IVNAA) measurement of manganese levels was investigated, with the goal being to have a means of monitoring both over exposed and manganese deficient populations. The McMaster KN-accelerator was used to provide low-energy neutrons, activation within an irradiation site occurred via the 55Mn(n,gamma) 56Mn capture reaction, and the 847 keV gamma-rays emitted when 56Mn decayed were measured using one or more Nal(TI) detectors. The present data regarding manganese metabolism and storage within the body are limited, and it is unclear what the optimal measurement site would be to provide a suitable biomarker of past exposure. Therefore the feasibility of IVNAA measurements in three sites was examined---the liver, brain and hand bones. Calibration curves were derived, minimum detectable limits determined and resulting doses calculated for each site (experimentally in the case of the liver and hand bones, and through computer simulations for the brain). Detailed analytical calculations of the 7Li(p,n) 7Be

  9. Laser induced neutron production by explosion of the deuterium clusters

    SciTech Connect

    Holkundkar, Amol R.; Mishra, Gaurav Gupta, N. K.

    2014-01-15

    The high energy deuterium ions serve as compact source of neutrons when fused with either deuterium or tritium atoms. In view of this, the explosion of the deuterium clusters under the influence of the laser pulse with intensity ranging from 10{sup 15} to 10{sup 19} W/cm{sup 2} is being studied along with the effect of the cluster radius and inter-cluster distance. The objective of this article is to study the efficiency of the deuterium cluster as a compact source of neutrons under various laser and cluster parameters. It is being observed that the cluster density (number of clusters per unit volume) is quite important to gain high neutron yield.

  10. Simulation of the neutron spectrum from the 7Li(p,n) reaction with a liquid-lithium target at Soreq Applied Research Accelerator Facility

    NASA Astrophysics Data System (ADS)

    Friedman, M.; Cohen, D.; Paul, M.; Berkovits, D.; Eisen, Y.; Feinberg, G.; Giorginis, G.; Halfon, S.; Krása, A.; Plompen, A. J. M.; Shor, A.

    2013-01-01

    The 7Li(p,n)7Be reaction has been used for the last 25 years to produce quasi-Maxwellian neutrons in order to measure Maxwellian-Averaged Cross-Sections in the relevant temperatures for stellar nucleosynthesis. A liquid-lithium target at the Soreq Applied Research Accelerator Facility is expected to allow us to perform such measurements at higher neutron intensities. Here we describe a Monte Carlo tool, SimLiT, developed to evaluate neutron spectra, intensities and angular distributions resulting from this reaction. We also demonstrate the feasibility to couple SimLiT with an advanced transport code, resulting in a powerful tool for planning and analysis of experiments using the 7Li(p,n) reaction as a neutron source.

  11. Neutron Production from Feedback Controlled Thermal Cycling of a Pyroelectric Crystal Stack

    SciTech Connect

    Tang, V; Meyer, G; Schmid, G; Spadaccini, C; Kerr, P; Rusnak, B; Sampayan, S; Naranjo, B; Putterman, S

    2007-08-09

    The LLNL Crystal Driven Neutron Source is operational and has produced record ion currents of {approx}10 nA and neutron output of 1.9 ({+-}0.3) x 10{sup 5} per thermal cycle using a crystal heating rate of 0.2 C/s from 10 C to 110 C. A 3 cm diameter by 1 cm thick LiTaO{sub 3} crystal with a socket secured field emitter tip is thermally cycled with feedback control for ionization and acceleration of deuterons onto a deuterated target to produce D-D fusion neutrons. The entire crystal and temperature system is mounted on a bellows which allows movement of the crystal along the beam axis and is completely contained on a single small vacuum flange. The modular crystal assembly permitted experimental flexibility. Operationally, flashover breakdowns along the side of the crystal and poor emitter tip characteristics can limit the neutron source. The experimental neutron results extend earlier published work by increasing the ion current and pulse length significantly to achieve a factor-of-two higher neutron output per thermal cycle. These findings are reviewed along with details of the instrument.

  12. Utilization of accelerators for transmutation and energy production

    SciTech Connect

    Sheffield, Richard L

    2010-09-24

    Given the increased concern over reliable, emission-free power, nuclear power has experienced a resurgence of interest. A sub-critical accelerator driven system (ADS) can drive systems that have either safety constraints (waste transmutation) or reduced fissile content (thorium reactor). The goals of ADS are some or all of the following: (1) to significantly reduce the generation or impacts due to the minor actinides on the packing density and long-term radiotoxicity in the repository design, (2) preserve/use the energy-rich component of used nuclear fuel, and (3) reduce proliferation risk. ADS systems have been actively studied in Europe and Asia over the past two decades and renewed interest is occurring in the U.S. This talk will cover some of the history, possible applicable fuel cycle scenarios, and general issues to be considered in implementing ADS systems.

  13. {product}Strong focusing and the radiofrequency quadrupole accelerator

    SciTech Connect

    Wangler, T.P.

    1996-02-01

    The {open_quote}{open_quote}New Problems{close_quote}{close_quote} department presents novel problems for use in undergraduate physics courses beyond the introductory level. In this article the problems and solutions use basic principles of electromagnetism to explain strong-focusing accelerator known as the radiofrequency quadrupole. Their solutions use Laplace{close_quote}s equation and require the extraction of information from boundary conditions. They also introduce the quasistatic approximation and show how under appropriate conditions Laplace{close_quote}s equation can be used to solve time-dependent problems. The problems are suitable for a course in electromagnetism and may be of interest for a cours in classical mechanics.

  14. A Fluka study of underground cosmogenic neutron production

    SciTech Connect

    Empl, A.; Hungerford, E.V.; Jasim, R.; Mosteiro, P. E-mail: evhunger@central.uh.edu E-mail: mosteiro@gmail.com

    2014-08-01

    Neutrons produced by cosmic muon interactions are important contributors to backgrounds in underground detectors when searching for rare events. Typically such neutrons can dominate the background, as they are particularly difficult to shield and detect. Since actual data is sparse and not well documented, simulation studies must be used to design shields and predict background rates. Thus validation of any simulation code is necessary to assure reliable results. This work compares in detail predictions of the FLUKA simulation code to existing data, and uses this code to report a simulation of cosmogenic backgrounds for typical detectors embedded in a water tank with liquid scintillator shielding.

  15. Production of charm mesons by high energy neutrons

    SciTech Connect

    Shipbaugh, C.L.

    1988-01-01

    The charmed mesons D/sup /plus minus//, D/sup 0/, and D/sub s//sup /plus minus//, have been observed in neutron-nucleus collisions at the FNAL Tevatron. A sample of 134 /plus minus/ 19 events as investigated in the decay D/sup /plus minus// /yields/ D/sup 0//pi//sup /plus minus// with the subsequent decay mode D/sup 0/ /yields/ K/sup +/K/sup /minus//. The cross section per nucleon for D/sup /plus minus//, at most probable energy /radical/s = 35 GeV, was measured to be 2.11 /plus minus/ .43 (plusreverse arrowminus/.63)/mu/b/nucleon for 0.0 < x/sub f/ < 0.14 (/bar x//sub f/ = .07). The branching ratio (BR) is defined as: BR /identicalreverse arrowto/ Br(D /yields/ D/pi/) /times/ BR(D /yields/ K/sup +/K/sup /minus//). The dependence of the cross section per nucleus on number of nucleons in target was fit to a form A /sup /alpha// and it was found that /alpha/ = .96 /plusreverse arrowminus/ .17. A sample of 64 /plusreverse arrowminus/ 16 D/sub s//sup /plus minus// events was investigates for the decay D/sub s//sup /plus minus// /yields/ /phi//pi//sup /plus minus//. The differential cross section for D/sub s//sup /plus minus// production averaged over the particle and antiparticle states is: BR.(1/2)(d/sigma/(D/sub s//sup +/)/dx/sub f/ + d/sigma/(D/sub s//sup /minus//) = 2.85 /plusreverse arrowminus/ 0.80 /plusreverse arrowminus/ .86 /mu/b/nucleon at x/sub f/ = 0.175 where the first errors is statistical and the second error is systematic. The branching fraction is defined as BR /equivalentreverse arrowto/ BR(D/sub s/ /yields/ /phi//pi/), and a linear A dependence was assumed. An estimate of relative cross section is: 0.19 /plusreverse arrowminus/ 0.09 at x/sub f/ = 0. 36 refs., 43 figs., 5 tabs.

  16. Production of charm mesons by high-energy neutrons

    SciTech Connect

    Shipbaugh, C.L.

    1988-01-01

    The charmed mesons ED{sup *{plus minus}}, D{sup 0}, and D{sub s}{sup {plus minus}} have been observed in neutron-nucleus collisions at the FNAL Tevatron. A sample of 134 {plus minus} 19 events was investigated in the decay mode D{sup *{plus minus}} {yields} D{sup 0} {pi}{sup {plus minus}} with the subsequent decay mode D{sup 0} {yields} K{sup +}K{sup {minus}}. The cross section per nucleon for D{sup *}{plus minus}, at most probable energy {radical}s = 35 GeV, was measured to be: d{sigma}(xf)/dxf {center dot} BR = 2.11 {plus minus} .43({plus minus}63){mu}b/nucleon for 0.0 < x{sub f} < 0.14 (x{sub f} = .07). The branching ratio (BR) is defined as: BR {identical to} BR(D{sup *} {yields} D{sub {pi}}) {times} BR(D {yields} K{sup +}K{sup {minus}}). The dependence of the cross section per nucleus on number of nucleons in the target was fit to a form A{sup {alpha}} and it was found that {alpha} = .96 {plus minus} .17. A sample of 64 {plus minus} 16 D{sub s}{sup {plus minus}} events was investigated for the decay D{sub s}{sup {plus minus}} {yields} {phi}{pi}{sup {plus minus}}. The differential cross section for D{sub s}{sup {plus minus}} production averaged over the particle and antiparticle states is: BR {center dot} {1/2} d{sigma}D{sub s}{sup +}/dxf + d{sigma}(D{sub s}{sup {minus}}/dxf) = 2.8 {plus minus} 0.80 {plus minus} .86 {mu}b/nucleon at x{sub f} = 0.175 where the first error is statistical and the second error is systematic. The branching fraction is defined as BR {identical to} BR(D{sub s} {yields} {phi}{pi}), and a linear A dependence was assumed.

  17. Absorption of gamma-ray photons in a vacuum neutron star magnetosphere: I. Electron-positron pair production

    SciTech Connect

    Istomin, Ya. N. Sob'yanin, D. N.

    2011-10-15

    The production of electron-positron pairs in a vacuum neutron star magnetosphere is investigated for both low (compared to the Schwinger one) and high magnetic fields. The case of a strong longitudinal electric field where the produced electrons and positrons acquire a stationary Lorentz factor in a short time is considered. The source of electron-positron pairs has been calculated with allowance made for the pair production by curvature and synchrotron photons. Synchrotron photons are shown to make a major contribution to the total pair production rate in a weak magnetic field. At the same time, the contribution from bremsstrahlung photons may be neglected. The existence of a time delay due to the finiteness of the electron and positron acceleration time leads to a great reduction in the electron-positron plasma generation rate compared to the case of a zero time delay. The effective local source of electron-positron pairs has been constructed. It can be used in the hydrodynamic equations that describe the development of a cascade after the absorption of a photon from the cosmic gamma-ray background in a neutron star magnetosphere.

  18. Environmental implications of accelerated gasohol production: preliminary assessment

    SciTech Connect

    Not Available

    1980-01-01

    This report assesses the environmental impacts of increasing US production of fuel ethanol by 330 million gallons per year in the 1980 to 1981 time frame in order to substitute gasohol for 10% of the unleaded gasoline consumed in the United States. Alternate biomass feedstocks are examined and corn is selected as the most logical feedstock, based on its availability and cost. Three corn conversion processes that could be used to attain the desired 1980 to 1981 production are identified; fermentation plants that use a feedstock of starch and wastes from an adjacent corn refining plants are found to have environmental and economic advantages. No insurmountable environmental problems can be achieved using current technology; the capital and operating costs of this control are estimated. If ethanol production is increased substantially after 1981, the environmentally acceptable use or disposal of stillage, a liquid by-product of fermentation, could become a serious problem.

  19. Accelerated pentose utilization by Corynebacterium glutamicum for accelerated production of lysine, glutamate, ornithine and putrescine.

    PubMed

    Meiswinkel, Tobias M; Gopinath, Vipin; Lindner, Steffen N; Nampoothiri, K Madhavan; Wendisch, Volker F

    2013-03-01

    Because of their abundance in hemicellulosic wastes arabinose and xylose are an interesting source of carbon for biotechnological production processes. Previous studies have engineered several Corynebacterium glutamicum strains for the utilization of arabinose and xylose, however, with inefficient xylose utilization capabilities. To improve xylose utilization, different xylose isomerase genes were tested in C. glutamicum. The gene originating from Xanthomonas campestris was shown to have the highest effect, resulting in growth rates of 0.14 h(-1), followed by genes from Bacillus subtilis, Mycobacterium smegmatis and Escherichia coli. To further increase xylose utilization different xylulokinase genes were expressed combined with X. campestris xylose isomerase gene. All combinations further increased growth rates of the recombinant strains up to 0.20 h(-1) and moreover increased biomass yields. The gene combination of X. campestris xylose isomerase and C. glutamicum xylulokinase was the fastest growing on xylose and compared with the previously described strain solely expressing E. coli xylose isomerase gene delivered a doubled growth rate. Productivity of the amino acids glutamate, lysine and ornithine, as well as the diamine putrescine was increased as well as final titres except for lysine where titres remained unchanged. Also productivity in medium containing rice straw hydrolysate as carbon source was increased. PMID:23164409

  20. Neutronics of accelerator-driven subcritical fission for burning transuranics in used nuclear fuel

    SciTech Connect

    Sattarov, A.; Assadi, S.; Badgley, K.; Baty, A.; Comeaux, J.; Gerity, J.; Kellams, J.; Mcintyre, P.; Pogue, N.; Sooby, E.; Tsvetkov, P.; Rosaire, G.; Mann, T.

    2013-04-19

    We report the development of a conceptual design for accelerator-driven subcritical fission in a molten salt core (ADSMS). ADSMS is capable of destroying all of the transuranics at the same rate and proportion as they are produced in a conventional nuclear power plant. The ADSMS core is fueled solely by transuranics extracted from used nuclear fuel and reduces its radiotoxicity by a factor 10,000. ADSMS offers a way to close the nuclear fuel cycle so that the full energy potential in the fertile fuels uranium and thorium can be recovered.

  1. Neutronics of accelerator-driven subcritical fission for burning transuranics in used nuclear fuel

    NASA Astrophysics Data System (ADS)

    Sattarov, A.; Assadi, S.; Badgley, K.; Baty, A.; Comeaux, J.; Gerity, J.; Kellams, J.; Mcintyre, P.; Pogue, N.; Sooby, E.; Tsvetkov, P.; Rosaire, G.; Mann, T.

    2013-04-01

    We report the development of a conceptual design for accelerator-driven subcritical fission in a molten salt core (ADSMS). ADSMS is capable of destroying all of the transuranics at the same rate and proportion as they are produced in a conventional nuclear power plant. The ADSMS core is fueled solely by transuranics extracted from used nuclear fuel and reduces its radiotoxicity by a factor 10,000. ADSMS offers a way to close the nuclear fuel cycle so that the full energy potential in the fertile fuels uranium and thorium can be recovered.

  2. ACCELERATED TESTING OF NEUTRON-ABSORBING ALLOYS FOR NUCLEAR CRITICALITY CONTROL

    SciTech Connect

    Ronald E. Mizia

    2011-10-01

    The US Department of Energy requires nuclear criticality control materials be used for storage of highly enriched spent nuclear fuel used in government programs and the storage of commercial spent nuclear fuel at the proposed High-Level Nuclear Waste Geological Repository located at Yucca Mountain, Nevada. Two different metallic alloys (Ni-Cr-Mo-Gd and borated stainless steel) have been chosen for this service. An accelerated corrosion test program to validate these materials for this application is described and a performance comparison is made.

  3. Direct current H{sup -} source for boron neutron capture therapy tandem accelerator

    SciTech Connect

    Belchenko, Yu.; Sanin, A.; Gusev, I.; Khilchenko, A.; Kvashnin, A.; Rashchenko, V.; Savkin, V.; Zubarev, P.

    2008-02-15

    One year experience of dc H{sup -} source operation at 2 MeV tandem accelerator is described. The source delivers H{sup -} ion beams with controlled current in the range of 1-8 mA and energy up to 25 keV. Normalized 1 rms emittance for 8 mA beam is less than 0.2{pi} mm mrad. Negative ions are produced on the cesiated anode of the Penning discharge, driven by plasma injection from the hollow cathode inserts.

  4. Optimizing Neutron Production Rates from D-D Fusion in an Inertial Electrostatic Confinement Device

    SciTech Connect

    Wehmeyer, A.L.; Radel, R.F.; Kulcinski, G.L.

    2005-05-15

    Detection of explosives has been identified as a near term commercial opportunity for using a fusion plasma. Typical explosive compositions contain low Z material (C, N, O) which are not easily detected using conventional x-rays or metal detectors. However, 2.45 MeV neutrons produced in a D-D fusion reaction can be used for detection of explosives or other clandestine materials in suitcases, packages, or shipping containers.Steady-state D-D operation is possible using an Inertial Electrostatic Confinement (IEC) fusion device. The University of Wisconsin IEC device has produced D-D neutrons at 1.8 x 10{sup 8} neutrons/second at a true cathode voltage of 166 kV and a meter current of 68 mA. These neutron production rates are approaching the levels required for the detection of explosives. In order to increase and optimize the neutron production rate in the IEC device, experiments were performed altering the cathode's size (diameter), geometry, and material composition. Preliminary results indicate that significant differences in neutron production rates are not achieved by altering the geometry or material composition of the cathode. However, the neutron production rate was found to increase approximately 20% by doubling the cathode's diameter from 10 cm to 20 cm. In addition, increasing the cathode voltage from 34 kV to 94 kV at a meter current of 30 mA increased the neutron production rate from 1.24 x 10{sup 6} n/s to 2.83 x 10{sup 7} n/s.

  5. Accelerator shielding design for PFNA applications

    SciTech Connect

    Shayer, Z.; Clayton, J.E.; Gozani, T. )

    1993-01-01

    The Pulsed Fast Neutron Analysis (PFNA) method utilizes the capability of high-energy neutrons to penetrate deeply and stimulate the emission of characteristic gamma rays that can be detected and used to identify and image the emitting chemical elements. The PFNA method interrogates the object using a directional beam consisting of short bursts of fast neutrons from a pulsed deuteron accelerator, with the neutrons generated in a deuteron gas target. In order to study the performance of the PFNA system, a National Electrostatics Corporation (NEC) Pelletron accelerator was acquired and installed at the Science Applications International Corporation (SAIC) facility in Santa Clara, California. The NEC Pelletron accelerator produces 6- or 12-MHz pulses of up to 6-MeV deuterons with a beam current that will reach up to 100 [mu]A. There are several identifiable radiation sources during operation of the PFNA system: (1) neutron production target and deuteron beam stop; (2) neutrons and gamma rays from the interrogation area; (3) X rays generated inside the accelerator because of free electrons between the accelerator tube segments, which are at different potentials; and (4) neutrons and gamma rays generated by deuteron striking limiting apertures within the acceleration column.

  6. Neutron production in the lunar subsurface from alpha particles in galactic cosmic rays

    NASA Astrophysics Data System (ADS)

    Ota, Shuya; Kobayashi, Shingo; Sihver, Lembit; Yamashita, Naoyuki; Hasebe, Nobuyuki

    2011-01-01

    The neutron production from alpha particles in galactic cosmic rays (GCR) in the lunar subsurface has not been estimated with reliable precision despite its importance for lunar nuclear spectroscopy and space dosimetry. Here, we report our estimation of neutron production from GCR nuclei (protons and alpha particles) with the Particle and Heavy Ion Transport code System (PHITS), which includes several heavy ion interaction models. PHITS simulations of the equilibrium neutron density profiles in the lunar subsurface are compared with experimental data obtained in the Apollo 17 Lunar Neutron Probe Experiment. Our calculations successfully reproduced the data within an experimental error of 15%. Our estimation of neutron production from GCR nuclei, estimated by scaling that from protons by a factor of 1.27, is in good agreement within an error of 1% with the calculations using two different alpha particle interaction models in PHITS during a period of average activity of the solar cycle. However, we show that the factor depends on the incident GCR spectrum model used in the simulation. Therefore, we conclude that the use of heavy ion interaction models is important for estimating neutron production in the lunar subsurface.

  7. Fusion of time-dependent gamma production spectra from thermal neutron capture and fast neutron inelastic scattering to improve material detection

    NASA Astrophysics Data System (ADS)

    Gozani, T.; Elsalim, M.; Strellis, D.; Brown, D.

    2003-06-01

    Neutron-based inspection techniques are unique in their ability to provide material specific signatures, thus offering very high performance and automatic detection of explosives and other contraband. Thermal neutron capture gamma spectroscopy provides excellent sensitivities to hydrogen, nitrogen, chlorine, and other elements, which are characteristic to most explosives, drugs and other contraband that may be smuggled into the country. Fast neutron gamma production (mostly through inelastic scattering) provides good sensitivity to carbon and oxygen. When necessary, these two types of complementary interactions can be combined to yield a more accurate material determination inside small to medium size containers. Standard pulsed 14 MeV electronic neutron generators offer an efficient way to obtain these two types of interactions. Fast (14 MeV) neutrons are produced during the pulse. After the pulse, only the decaying thermal neutron population exists, and thus pure neutron capture gamma-rays are produced. Unfortunately, during the pulse (which is normally much longer than the neutron thermalization time) the fast neutron interactions are highly "contaminated" by the interactions of thermal neutrons within the object and the nearby gamma-ray detectors. This creates high background and spectral interferences in the common medium resolution detectors, such as NaI, BGO, etc. The use of an appropriate shielding, neutron spectrum tailoring, full spectral feature analysis as well as temporal information ("die-away" time) resulted in significant performance enhancements in detection of explosives, drugs and other contraband in difficult geometries.

  8. Microbial Metabolite Production for Accelerated Metal and Radionuclide Bioremediation (Microbial Metabolite Production Report)

    SciTech Connect

    TURICK, CHARLES

    2004-09-21

    to about 2-4 percent of the humic fraction of soils. Our recent work has shown that melanin production by one species of bacteria could be used by other species for metal reduction. This melanin ''sharing'' is the area of focus for this project. In addition, melanin contributes to significant increases in metal reduction by both assimilatory and dissimilatory metal reducing bacteria. Stimulation of melanin production in the subsurface offers potential for accelerating metal reduction. Another focus of this project was to determine the potential of melanin production in portions of the Tims Branch watershed as it relates to metal and radionuclide immobilization in-situ.

  9. Neutronics Study on Accelerator Driven Subcritical Systems with Thorium-Based Fuel for Comparison Between Solid and Molten-Salt Fuels

    SciTech Connect

    Ishimoto, Shunsuke; Ishibashi, Kenji; Tenzou, Hideki; Sasa, Toshinobu

    2002-06-15

    Since thorium is an abundant fertile material, there is hope for the thorium-cycle fuels for an accelerator driven subcritical system (ADS). The ADS utilizes neutrons, which are generated by high-energy protons of giga-electron-volt-grade, but cross sections for the interaction of high-energy particles are not available for use in current ADS engineering design. In this paper the neutron behavior in the ADS target based on the related experimental data is clarified, and the feasibility of the ADS regarding both the molten salts (Flibe: {sup 7}LiF-BeF{sub 2}-ThF{sub 4}-{sup 233}UF{sub 4}, chloride: NaCl-ThCl{sub 4}-{sup 233}UCl{sub 4}) and oxide ([Th, {sup 233}U]O{sub 2}) fuels is examined. The difference between the experiment and the calculated result at the ADS high-energy region is discussed. In a comparison of the fuels, the time evolution of k{sub eff} and the beam current in the burning period are calculated. The calculated results suggest that the ADS with solid fuel has better future prospects than that with molten-salt fuels. The ADS with Flibe molten-salt fuel tends to require a high beam current and consequently needs the installation of a metallic spallation target and the continuous removal for fission products and protactinium. In comparison with the Flibe fuel, the ADS with chloride fuel has a flux distribution that is similar to a solid fuel reactor.

  10. Neutron sources: Present practice and future potential

    SciTech Connect

    Cierjacks, S.; Smith, A.B.

    1988-01-01

    The present capability and future potential of accelerator-based monoenergetic and white neutron sources are outlined in the context of fundamental and applied neutron-nuclear research. The neutron energy range extends from thermal to 500 MeV, and the time domain from steady-state to pico-second pulsed sources. Accelerator technology is summarized, including the production of intense light-ion, heavy-ion and electron beams. Target capabilities are discussed with attention to neutron-producing efficiency and power-handling capabilities. The status of underlying neutron-producing reactions is summarized. The present and future use of neutron sources in: fundamental neutron-nuclear research, nuclear data acquisition, materials damage studies, engineering tests, and biomedical applications are discussed. Emphasis is given to current status, near-term advances well within current technology, and to long-range projections. 90 refs., 4 figs.

  11. Neutron production from beam-modifying devices in a modern double scattering proton therapy beam delivery system

    PubMed Central

    Pérez-Andújar, Angélica; Newhauser, Wayne D; DeLuca, Paul M

    2014-01-01

    In this work the neutron production in a passive beam delivery system was investigated. Secondary particles including neutrons are created as the proton beam interacts with beam shaping devices in the treatment head. Stray neutron exposure to the whole body may increase the risk that the patient develops a radiogenic cancer years or decades after radiotherapy. We simulated a passive proton beam delivery system with double scattering technology to determine the neutron production and energy distribution at 200 MeV proton energy. Specifically, we studied the neutron absorbed dose per therapeutic absorbed dose, the neutron absorbed dose per source particle and the neutron energy spectrum at various locations around the nozzle. We also investigated the neutron production along the nozzle's central axis. The absorbed doses and neutron spectra were simulated with the MCNPX Monte Carlo code. The simulations revealed that the range modulation wheel (RMW) is the most intense neutron source of any of the beam spreading devices within the nozzle. This finding suggests that it may be helpful to refine the design of the RMW assembly, e.g., by adding local shielding, to suppress neutron-induced damage to components in the nozzle and to reduce the shielding thickness of the treatment vault. The simulations also revealed that the neutron dose to the patient is predominated by neutrons produced in the field defining collimator assembly, located just upstream of the patient. PMID:19147903

  12. Neutron production from beam-modifying devices in a modern double scattering proton therapy beam delivery system.

    PubMed

    Pérez-Andújar, Angélica; Newhauser, Wayne D; Deluca, Paul M

    2009-02-21

    In this work the neutron production in a passive beam delivery system was investigated. Secondary particles including neutrons are created as the proton beam interacts with beam shaping devices in the treatment head. Stray neutron exposure to the whole body may increase the risk that the patient develops a radiogenic cancer years or decades after radiotherapy. We simulated a passive proton beam delivery system with double scattering technology to determine the neutron production and energy distribution at 200 MeV proton energy. Specifically, we studied the neutron absorbed dose per therapeutic absorbed dose, the neutron absorbed dose per source particle and the neutron energy spectrum at various locations around the nozzle. We also investigated the neutron production along the nozzle's central axis. The absorbed doses and neutron spectra were simulated with the MCNPX Monte Carlo code. The simulations revealed that the range modulation wheel (RMW) is the most intense neutron source of any of the beam spreading devices within the nozzle. This finding suggests that it may be helpful to refine the design of the RMW assembly, e.g., by adding local shielding, to suppress neutron-induced damage to components in the nozzle and to reduce the shielding thickness of the treatment vault. The simulations also revealed that the neutron dose to the patient is predominated by neutrons produced in the field defining collimator assembly, located just upstream of the patient. PMID:19147903

  13. Determination of cross sections of 60Ni(n,2n)59Ni induced by 14 MeV neutrons with accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    He, Ming; Xu, Yongning; Guan, Yongjing; Shen, Hongtao; Du, Liang; Hongtao, Chen; Dong, Kejun; Jiang, Shan; Yang, Xuran; Wang, Xiaoming; Ruan, Xiang dong; Liu, Jiancheng; Wu, Shaoyong; Zhao, Qingzhang; Cai, Li; Pang, Fangfang

    2015-10-01

    The cross section of the 60Ni(n,2n)59Ni induced by neutron with energy around 14 MeV is important for a fusion environment. However, the published values are strongly discordant. By taking advantage of the high sensitivity of 59Ni measurement at China Institute of Atomic Energy (CIAE), determination of the cross section has been carried out. A natural Nickel foil was irradiated by neutrons produce by a T(D,n)α neutron generator. 57Co and 58Co which produced in the Nickel foil were chosen for the neutron fluence determination. Then the ratio of 59Ni/60Ni for the irradiated sample was determined via accelerator mass spectrometry (AMS) utilizing a 13MV tandem accelerator and a Q3D magnet spectrometry at CIAE. As a result, the cross section of 60Ni(n,2n)59Ni for the incident neutron energy of (14.60 ± 0.40) MeV was determined to be (426 ± 53) mb.

  14. Using Gamma-Ray and Neutron Emission to Determine Solar Flare Accelerated Particle Spectra and Composition and the Conditions within the Flare Magnetic Loop

    NASA Astrophysics Data System (ADS)

    Murphy, R. J.; Kozlovsky, Benzion; Share, G. H.; Hua, X.-M.; Lingenfelter, R. E.

    2007-01-01

    The measurable quantities associated with γ-ray and neutron observations of solar flares are nuclear-deexcitation line shapes, shifts, fluences, and time histories; neutron capture and annihilation line fluences and time histories; and energy-dependent escaping neutron fluence and time history. A comprehensive understanding of these quantities requires a model for ion acceleration, transport, and interaction. In this paper we address transport and interaction using a magnetic loop model that includes energy losses due to Coulomb collisions, removal by nuclear reactions, magnetic mirroring in the convergent flux tube, and MHD pitch-angle scattering in the corona. The accelerated ions are assumed to have a given kinetic energy spectrum and composition. Each measurable quantity depends to varying degree on the parameters of the loop model and of the accelerated ions. We explore these dependences in detail and construct a self-consistent approach to the analysis of high-energy flare data that provides an optimum set of parameters with meaningful uncertainties. To illustrate this approach, the calculations are applied in a comprehensive analysis of the γ-ray and neutron observations of the 1991 June 4 solar flare obtained with OSSE on CGRO. We find that the loop model can account for these observations with physically reasonable values for the parameters. In addition, our analysis of the neutron data shows that the accelerated ion spectrum for this flare was not an unbroken power law but had to steepen sharply above ~125 MeV nucleon-1. The paper also provides yields and yield ratios calculated with assumed abundances and spectral forms currently considered appropriate for solar flares. They can be used by other researchers analyzing high-energy solar flare data.

  15. High-power electron beam tests of a liquid-lithium target and characterization study of (7)Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy.

    PubMed

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Cohen, D; Eliyahu, I; Kijel, D; Mardor, I; Silverman, I

    2014-06-01

    A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (σ=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors. PMID:24387907

  16. Reactions and moderators for an accelerator-based epithermal neutron capture therapy source for cancer treatment. Final report, October 1900--September 1994

    SciTech Connect

    Kunze, J.F.; Brugger, R.M.

    1995-03-01

    The use of boron neutron capture therapy (BNCT) has been considered for nearly 30 years, and been practiced in Japan since the late 1970`s. Early experiments in the USA were generally nonpromising. However, new boron-containing ligand compounds were developed, which would seek out brain tumors. Concentration levels of the order of 30 micrograms of boron per gram of tissue become possible, and interest in the BNCT technique was revived in the USA beginning about 1985, with research reactors as the obvious source of the neutrons for the treatment. However, the limited number of research reactors in the USA (and the world) would mean that this treatment modality would be quite limited. The goals of this work was: (1) Examine as many as possible reactions of charged particles on various targets of an accelerator, and determine those that would give high neutron yields of a convenient energy. (2) Determine, through calculations (using Monte Carlo stochastic computer codes), the best design for a moderator/reflector assembly which would give high thermal flux at a nominal 5 cm depth in the head of a patient, with minimal radiation dose from gamma rays and fast neutrons. (3) Perform a benchmark experiment using a positive ion accelerator. The Li-7(p,n) reaction was chosen for the benchmark, since it was readily available for most accelerators, and was one of the two highest yielding reactions from Task No. 1. Since the University of Missouri has no accelerator, possible accelerators at other universities were investigated, as to availability and cost. A unit having capability in the 2.5 MeV range was desired.

  17. Hybrid photoneutron source optimization for electron accelerator-based BNCT

    NASA Astrophysics Data System (ADS)

    Rahmani, F.; Shahriari, M.

    2010-06-01

    Boron Neutron Capture Therapy (BNCT) is being studied as a possible radiotherapic treatment for some cancer types. Neutron energy for penetrating into tissue should be in the epithermal range. Different methods are used for neutron production. Electron accelerators are an alternative way for producing neutrons in electron-photon-neutron processes. Optimization of electron/photon and photoneutron targets calculations with respect to electron energy, dimension (radius and thickness) and neutron yield were done by MCNPX Monte Carlo code. According to the results, a hybrid photoneutron source including BeD 2 and Tungsten has been introduced.

  18. GPU Acceleration of Mean Free Path Based Kernel Density Estimators for Monte Carlo Neutronics Simulations

    SciTech Connect

    Burke, TImothy P.; Kiedrowski, Brian C.; Martin, William R.; Brown, Forrest B.

    2015-11-19

    Kernel Density Estimators (KDEs) are a non-parametric density estimation technique that has recently been applied to Monte Carlo radiation transport simulations. Kernel density estimators are an alternative to histogram tallies for obtaining global solutions in Monte Carlo tallies. With KDEs, a single event, either a collision or particle track, can contribute to the score at multiple tally points with the uncertainty at those points being independent of the desired resolution of the solution. Thus, KDEs show potential for obtaining estimates of a global solution with reduced variance when compared to a histogram. Previously, KDEs have been applied to neutronics for one-group reactor physics problems and fixed source shielding applications. However, little work was done to obtain reaction rates using KDEs. This paper introduces a new form of the MFP KDE that is capable of handling general geometries. Furthermore, extending the MFP KDE to 2-D problems in continuous energy introduces inaccuracies to the solution. An ad-hoc solution to these inaccuracies is introduced that produces errors smaller than 4% at material interfaces.

  19. Asymmetric neutrino production in magnetized proto-neutron stars in fully relativistic mean-field approach

    SciTech Connect

    Maruyama, Tomoyuki; Kajino, Toshitaka; Hidaka, Jun; Takiwaki, Tomoya; Yasutake, Nobutoshi; Kuroda, Takami; Cheoun, Myung-Ki; Ryu, Chung-Yeol; Mathews, Grant J.

    2014-05-02

    We calculate the neutrino production cross-section in the proto-neutron-star matter under a strong magnetic field in the relativistic mean-field approach. We introduce a new parameter-set which can reproduce the 1.96 solar mass neutron star. We find that the production process increases emitted neutrinos along the direction parallel to the magnetic field and decrease those along its opposite direction. It means that resultant asymmetry due to the neutrino absorption and scattering process in the magnetic field becomes larger by the addition of the neutrino production process.

  20. Comparison of photon-photon and photon-magnetic field pair production rates. [in neutron stars

    NASA Technical Reports Server (NTRS)

    Burns, M. L.; Harding, A. K.

    1983-01-01

    Neutron stars were proposed as the site of gamma-ray burst activity and the copious supply of MeV photons admits the possibility of electron-positron pair production. If the neutron star magnetic field is sufficiently intense (10 to the 12th power G), both photon-photon (2 gamma) and photon-magnetic field (gamma) pair production should be important mechanisms. Rates for the two processes were calculated using a Maxwellian distribution for the photons. The ratio of 1 gamma to 2 gamma pair production rates was obtained as a function of photon temperature and magnetic field strength.

  1. Determination of solar flare accelerated ion angular distributions from SMM gamma ray and neutron measurements and determination of the He-3/H ratio in the solar photosphere from SMM gamma ray measurements

    NASA Technical Reports Server (NTRS)

    Lingenfelter, Richard E.

    1989-01-01

    Comparisons of Solar Maximum Mission (SMM) observations of gamma-ray line and neutron emission with theoretical calculation of their expected production by flare accelerated ion interactions in the solar atmosphere have led to significant advances in the understanding of solar flare particle acceleration and interaction, as well as the flare process itself. These comparisons have enabled the determination of, not only the total number and energy spectrum of accelerated ions trapped at the sun, but also the ion angular distribution as they interact in the solar atmosphere. The Monte Carlo program was modified to include in the calculations of ion trajectories the effects of both mirroring in converging magnetic fields and of pitch angle scattering. Comparing the results of these calculations with the SMM observations, not only the angular distribution of the interacting ions can be determined, but also the initial angular distribution of the ions at acceleration. The reliable determination of the solar photospheric He-3 abundance is of great importance for understanding nucleosynthesis in the early universe and its implications for cosmology, as well as for the study of the evolution of the sun. It is also essential for the determinations of the spectrum and total number of flare accelerated ions from the SMM/GRS gamma-ray line measurements. Systematic Monte Carlo calculations of the time dependence were made as a function of the He-3 abundance and other variables. A new series of calculations were compared for the time-dependent flux of 2.223 MeV neutron capture line emission and the ratio of the time-integrated flux in the 2.223 MeV line to that in the 4.1 to 6.4 MeV nuclear deexcitation band.

  2. Neutron and antineutron production in accretion onto compact objects

    NASA Technical Reports Server (NTRS)

    Dermer, Charles D.; Ramaty, Reuven

    1986-01-01

    Nuclear reactions in the hot accretion plasma surrounding a collapsed star are a source of neutrons, primarily through spallation and pion-producing reactions, and antineutrons, principally through the reaction p+p yields p+p+n+anti-n. We calculate spectra of neutrons and antineutrons produced by a variety of nonthermal energetic particle distributions in which the target particles are either at rest or in motion. If only neutral particles are free to escape the interaction site, a component of the proton and antiproton fluxes in the cosmic radiation results from the neutrons and antineutrons which leave the accretion plasma and subsequently decay in the interstellar medium. This additional antiproton component could account for the enhanced flux of antiprotons in the cosmic radiation, compared to values expected from the standard leaky-box model of cosmic-ray propagation and confinement. Moreover, the low-energy antiproton flux measured by Buffington et al. (1981) could result from target-particle motion in the accretion plasma. This model for the origin of antiprotons predicts a narrow 2.223 MeV line which could be observable.

  3. An aerial radiological survey of the neutron products company and surrounding area

    SciTech Connect

    Vojtech, R.J.

    1994-12-01

    An aerial radiological survey was conducted from November 1-10, 1993, over the Neutron Products Company and neighboring areas. The company, located in Dickerson, Maryland, has two major operations involving the radioisotope cobalt-60 ({sup 60}Co)-the manufacture of commercial {sup 60}Co sources and the sterilization of medical products by exposure to radiation. The sterilization facility consists of two {sup 60}Co sources with activities of approximately 500,000 and 1,500,000 Ci, respectively. The purpose of the aerial survey was to detect and document any anomalous gamma-emitting radionuclides in the environment which may have resulted from operations of the Neutron Products Company. The survey covered two areas: the first was a 6.5- by 6.5-kilometer area centered over the Neutron Products facility; the second area was a 2- by 2.5-kilometer region surrounding a waste pumping station on Muddy Branch in Gaithersburg, Maryland. This site is approximately fifteen kilometers southeast of the Neutron Products facility and was included because sanitary and other liquid waste materials from the plant site are being disposed of at the pumping station. Contour maps showing gamma radiation exposure rates at 1 meter above ground level, overlaid on an aerial photo of the area, were constructed from the data measured during the flights. The exposure rates measured within the survey regions were generally uniform and typical of rates resulting from natural background radiation. Only one area showed an enhanced exposure rate not attributable to natural background. This area, located directly over the Neutron Products facility, was analyzed and identified as {sup 60}Co, the radioisotope used in the irradiation and source production operations conducted at the Neutron Products Company. The measurements over the Muddy Branch area in Gaithersburg were typical of natural background radiation and showed no evidence of {sup 60}Co or any other man-made radionuclide.

  4. Laser plasma acceleration of electrons: Towards the production of monoenergetic beams

    SciTech Connect

    Krushelnick, K.; Najmudin, Z.; Mangles, S.P.D.; Thomas, A.G.R.; Wei, M.S.; Walton, B.; Gopal, A.; Clark, E.L.; Dangor, A.E.; Fritzler, S.; Murphy, C.D.; Norreys, P.A.; Mori, W.B.; Gallacher, J.; Jaroszynski, D.; Viskup, R.

    2005-05-15

    The interaction of high intensity laser pulses with underdense plasma is investigated experimentally using a range of laser parameters and energetic electron production mechanisms are compared. It is clear that the physics of these interactions changes significantly depending not only on the interaction intensity but also on the laser pulse length. For high intensity laser interactions in the picosecond pulse duration regime the production of energetic electrons is highly correlated with the production of plasma waves. However as intensities are increased the peak electron acceleration increases beyond that which can be produced from single stage plasma wave acceleration and direct laser acceleration mechanisms must be invoked. If, alternatively, the pulse length is reduced such that it approaches the plasma period of a relativistic electron plasma wave, high power interactions can be shown to enable the generation of quasimonoenergetic beams of relativistic electrons.

  5. Positron production using a 1.7 MV pelletron accelerator

    SciTech Connect

    Alcantara, K. F.; Santos, A. C. F.; Crivelli, P.

    2013-04-19

    We report the foremost phase of a fourth generation positron source, being constructed at the Federal University of Rio de Janeiro. Positron yields are reported by making use of the {sup 19}F(p,{alpha}e{sup +}e{sup -}){sup 16}O reaction, where the fluorine target is in the form of a CaF{sub 2} pellet. Positron production has been observed by detecting 511 keV annihilation gamma rays emerging from the irradiated CaF{sub 2} target.

  6. ACCELERATING FUSION REACTOR NEUTRONICS MODELING BY AUTOMATIC COUPLING OF HYBRID MONTE CARLO/DETERMINISTIC TRANSPORT ON CAD GEOMETRY

    SciTech Connect

    Biondo, Elliott D; Ibrahim, Ahmad M; Mosher, Scott W; Grove, Robert E

    2015-01-01

    Detailed radiation transport calculations are necessary for many aspects of the design of fusion energy systems (FES) such as ensuring occupational safety, assessing the activation of system components for waste disposal, and maintaining cryogenic temperatures within superconducting magnets. Hybrid Monte Carlo (MC)/deterministic techniques are necessary for this analysis because FES are large, heavily shielded, and contain streaming paths that can only be resolved with MC. The tremendous complexity of FES necessitates the use of CAD geometry for design and analysis. Previous ITER analysis has required the translation of CAD geometry to MCNP5 form in order to use the AutomateD VAriaNce reducTion Generator (ADVANTG) for hybrid MC/deterministic transport. In this work, ADVANTG was modified to support CAD geometry, allowing hybrid (MC)/deterministic transport to be done automatically and eliminating the need for this translation step. This was done by adding a new ray tracing routine to ADVANTG for CAD geometries using the Direct Accelerated Geometry Monte Carlo (DAGMC) software library. This new capability is demonstrated with a prompt dose rate calculation for an ITER computational benchmark problem using both the Consistent Adjoint Driven Importance Sampling (CADIS) method an the Forward Weighted (FW)-CADIS method. The variance reduction parameters produced by ADVANTG are shown to be the same using CAD geometry and standard MCNP5 geometry. Significant speedups were observed for both neutrons (as high as a factor of 7.1) and photons (as high as a factor of 59.6).

  7. High power testing of the 402.5 MHZ and 805 MHZ RF windows for the spallation neutron source accelerator

    SciTech Connect

    Cummings, K. A.; De Baca, J. M.; Harrison, J. S.; Rodriguez, M. B.; Torrez, P. A.; Warner, D. K.

    2003-01-01

    Hisorically, Radio Frequency (RF) windows have been a common point of failure in input power couplers; therefore, reliable RF windows are critical to the success of the Spallation Neutron Source (SNS) project. The normal conducting part of the SNS accelerator requires six RF windows at 402.5 MHz and eight RF windows at 805 MHz[l]. Each RF window will transmit up to 180 kW of average power and 2.5 MW peak power at 60 Hz with 1.2 millisecond pulses. The RF windows, designed and manufactured by Thales, were tested at the full average power for 4 hours to ensure no problems with the high average power and then tested to an effective forward power level of 10 MW by testing at 2.5 MW forward power into a short and varying the phase of the standing wave. The sliding short was moved from 0 to 180 degrees to ensure no arcing or breakdown problems occur in any part of the window. This paper discusses the results of the high power testing of both the 402.5 MHz and the 805 MHz RF windows. Problems encountered during testing and the solutions for these problems are discussed.

  8. Secondary neutron-production cross sections from heavy-ion interactions in composite targets

    SciTech Connect

    Heilbronn, L.; Iwata, Y.; Murakami, T.; Iwase, H.; Sato, H.; Nakamura, T.; Ronningen, R.M.; Ieki, K.; Gudowska, I.; Sobolevsky, N.

    2006-02-15

    Secondary neutron-production cross sections have been measured from interactions of 290 MeV/nucleon C and 600 MeV/nucleon Ne in a target composed of simulated Martian regolith and polyethylene, and from 400 MeV/nucleon Ne interactions in wall material from the International Space Station. The data were measured between 5 deg. and 80 deg. in the laboratory. We report the double-differential cross sections, angular distributions, and total neutron-production cross sections from all three systems. The spectra from all three systems exhibit behavior previously reported in other heavy-ion neutron-production experiments, namely, a peak at forward angles near the energy corresponding to the beam velocity, with the remaining spectra generated by pre-equilibrium and equilibrium processes. The double-differential cross sections are fitted with a moving-source parametrization. Also reported are the data without corrections for neutron flux attenuation in the target and other intervening materials and for neutron production in nontarget materials near the target position. These uncorrected spectra are compared with SHIELD-HIT and PHITS transport model calculations. The transport model calculations reproduce the spectral shapes well but, on average, underestimate the magnitudes of the cross sections.

  9. Secondary neutron-production cross sections from heavy-ioninteractions in composite targets.

    SciTech Connect

    Heilbronn, L.; Iwata, Y.; Iwase,H.; Murakami, T.; Sato, H.; Nakamura, T.; Ronningen, R.M.; Ieki, K.; Gudowska, I.; Sobolevsky, N.

    2005-12-19

    Secondary neutron-production cross-sections have been measured from interactions of 290 MeV/nucleon C and 600 MeV/nucleon Ne in a target composed of simulated Martian regolith and polyethylene, and from 400 MeV/nucleon Ne interactions in wall material from the International Space Station. The data were measured between 5 and 80 deg in the laboratory. We report the double-differential cross sections, angular distributions, and total neutron-production cross sections from all three systems. The spectra from all three systems exhibit behavior previously reported in other heavy-ion, neutron production experiments; namely, a peak at forward angles near the energy corresponding to the beam velocity, with the remaining spectra generated by pre-equilibrium and equilibrium processes. The double differential cross sections are fitted with a moving-source parameterization. Also reported are the data without corrections for neutron flux attenuation in the target and other intervening materials, and for neutron production in non-target materials near the target position. These uncorrected spectra are compared with SHIELD-HIT and PHITS transport model calculations. The transport model calculations reproduce the spectral shapes well, but, on average, underestimate the magnitudes of the cross sections.

  10. Vacuum seals design and testing for a linear accelerator of the National Spallation Neutron Source

    SciTech Connect

    Z. Chen; C. Gautier; F. Hemez; N. K. Bultman

    2000-02-01

    Vacuum seals are very important to ensure that the Spallation Neutron Source (SNS) Linac has an optimum vacuum system. The vacuum joints between flanges must have reliable seals to minimize the leak rate and meet vacuum and electrical requirements. In addition, it is desirable to simplify the installation and thereby also simplify the maintenance required. This report summarizes an investigation of the metal vacuum seals that include the metal C-seal, Energized Spring seal, Helcoflex Copper Delta seal, Aluminum Delta seal, delta seal with limiting ring, and the prototype of the copper diamond seals. The report also contains the material certifications, design, finite element analysis, and testing for all of these seals. It is a valuable reference for any vacuum system design. To evaluate the suitability of several types of metal seals for use in the SNS Linac and to determine the torque applied on the bolts, a series of vacuum leak rate tests on the metal seals have been completed at Los Alamos Laboratory. A copper plated flange, using the same type of delta seal that was used for testing with the stainless steel flange, has also been studied and tested. A vacuum seal is desired that requires significantly less loading than a standard ConFlat flange with a copper gasket for the coupling cavity assembly. To save the intersegment space the authors use thinner flanges in the design. The leak rate of the thin ConFlat flange with a copper gasket is a baseline for the vacuum test on all seals and thin flanges. A finite element analysis of a long coupling cavity flange with a copper delta seal has been performed in order to confirm the design of the long coupling cavity flange and the welded area of a cavity body with the flange. This analysis is also necessary to predict a potential deformation of the cavity under the combined force of atmospheric pressure and the seating load of the seal. Modeling of this assembly has been achieved using both HKS/Abaqus and COSMOS

  11. Activation Measurements for Thermal Neutrons, U.S. Measurements of 36Cl in Mineral Samples from Hiroshima and Nagasaki; and Measurement of 63 Ni in Copper Samples From Hiroshima by Accelerator Mass Spectrometry

    SciTech Connect

    Tore Straume; Alfredo A. Marchetti; Stephen D. Egbert; James A. Roberts; Ping Men; Shoichiro Fujita; Kiyoshi Shizuma; Masaharu Hoshi; G. Rugel; W. Ruhm; G. Korschinek; J. E. McAninch; K. L. Carroll; T. Faestermann; K. Knie; R. E. Martinelli; A. Wallner; C. Wallner

    2005-01-14

    The present paper presents the {sup 36}Cl measurement effort in the US. A large number of {sup 36}Cl measurements have been made in both granite and concrete samples obtained from various locations and distances in Hiroshima and Nagasaki. These measurements employed accelerator mass spectrometry (AMS) to quantify the number of atoms of {sup 36}Cl per atom of total Cl in the sample. Results from these measurements are presented here and discussed in the context of the DS02 dosimetry reevaluation effort for Hiroshima and Nagasaki atomic-bomb survivors. The production of {sup 36}Cl by bomb neutrons in mineral samples from Hiroshima and Nagasaki was primarily via the reaction {sup 35}Cl(n,{gamma}){sup 36}Cl. This reaction has a substantial thermal neutron cross-section (43.6 b at 0.025 eV) and the product has a long half-life (301,000 y). hence, it is well suited for neutron-activation detection in Hiroshima and Nagasaki using AMS more than 50 years after the bombings. A less important reaction for bomb neutrons, {sup 39}K(n,{alpha}){sup 36}Cl, typically produces less than 10% of the {sup 36}Cl in mineral samples such as granite and concrete, which contain {approx} 2% potassium. In 1988, only a year after the publication of the DS86 final report (Roesch 1987), it was demonstrated experimentally that {sup 36}Cl measured using AMS should be able to detect the thermal neutron fluences at the large distances most relevant to the A-bomb survivor dosimetry. Subsequent measurements in mineral samples from both Hiroshima and Nagasaki validated the experimental findings. The potential utility of {sup 36}Cl as a thermal neutron detector in Hiroshima was first presented by Haberstock et al. who employed the Munich AMS facility to measure {sup 36}Cl/Cl ratios in a gravestone from near the hypocenter. That work subsequently resulted in an expanded {sup 36}Cl effort in Germany that paralleled the US work. More recently, there have also been {sup 36}Cl measurements made by a Japanese

  12. Experimental study on anomalous neutron production in deuterium/solid system

    SciTech Connect

    He Jianyu; Zhu Rongbao; Wang Xiaozhong; Lu Feng; Luo Longjun; Liu Hengjun; Jiang Jincai; Tian Baosheng; Chen Guoan; Yuan Yuan; Dong Baiting; Yang Liucheng; Qiao Shengzhong; Yi Guoan; Guo Hua; Ding Dazhao ); Menlove, H.O. )

    1991-05-10

    A series of experiments on both D{sub 2}O electrolysis and thermal cycle of deuterium absorbed Ti Turnings has been designed to examine the anomalous phenomena in Deuterium/Solid System. A neutron detector containing 16 BF{sub 3} tubes with a detection limit of 0.38 n/s for two hour counting was used for electrolysis experiments. No neutron counting rate statistically higher than detection limit was observed from Fleischmann Pons type experiments. An HLNCC neutron detector equipped with 18 {sup 3}He tubes and a JSR-11 shift register unit with a detection limit of 0.20 n/s for a two hour run was employed to study the neutron signals in D{sub 2} gas experiments. Different material pretreatments were selected to review the changes in frequency and size of the neutron burst production. Experiment sequence was deliberately designed to distinguish the neutron burst from fake signals, e.g. electronic noise pickup, the cosmic rays and other sources of environmental background. Ten batches of dry fusion samples were tested, among them, seven batches with neutron burst signals occurred roughly at the temperature from {minus}100 degree centigrade to near room temperature. In the first four runs of a typical sample batch, seven neutron bursts were observed with neutron numbers from 15 to 482, which are 3 and 75 times, respectively, higher than the uncertainty of background. However, no bursts happened for H{sub 2} dummy samples running in-between and afterwards and for sample batch after certain runs.

  13. Production and supply of radioisotopes with high-energy particle accelerators current status and future directions

    SciTech Connect

    Srivastava, S.C.; Mausner, L.F.

    1994-03-01

    Although the production of radioisotopes in reactors or in low to medium energy cyclotrons appears to be relatively well established, especially for those isotopes that are routinely used and have a commercial market, certain isotopes can either be made only in high-energy particle accelerators or their production is more cost effective when made this way. These facilities are extremely expensive to build and operate, and isotope production is, in general, either not cost-effective or is in conflict with their primary mandate or missions which involve physics research. Isotope production using high-energy accelerators in the US, therefore, has been only an intermittent and parasitic activity. However, since a number of isotopes produced at higher energies are emerging as being potentially useful for medical and other applications, there is a renewed concern about their availability in a continuous and reliable fashion. In the US, in particular, the various aspects of the prediction and availability of radioisotopes from high-energy accelerators are presently undergoing a detailed scrutiny and review by various scientific and professional organizations as well as the Government. A number of new factors has complicated the supply/demand equation. These include considerations of cost versus needs, reliability factors, mission orientation, research and educational components, and commercial viability. This paper will focus on the present status and projected needs of radioisotope production with high-energy accelerators in the US, and will compare and examine the existing infrastructure in other countries for this purpose.

  14. Neutron production from puffing deuterium in plasma focus device

    SciTech Connect

    Kubes, P.; Cikhardt, J.; Kortanek, J.; Batobolotova, B.; Rezac, K.; Klir, D.; Kravarik, J.; Paduch, M.; Zielinska, E.; Surala, W.; Sadowski, M. J.; Scholz, M.; Karpinski, L.

    2014-08-15

    The current research has continued on the PF-1000 plasma focus device at the current of 2 MA by comparison of the shots with and without injected deuterium. The increase of the total neutron yield at the level of 10{sup 10}–10{sup 11} per shot was achieved after the compression of about 10 μg/cm of the deuterium from the gas-valve by about 46 μg/cm of the neon or deuterium plasma sheath. It increases five times at the decrease of the puffing deuterium mass to one-half. In shots with neon in the chamber and with puffing deuterium, a considerable decrease was confirmed of the soft X-ray emission in comparison with shots without deuterium injection. This decrease can be explained by the absence of the neon in the region of the compressed and hot plasma. The deuterium plasma from the gas-puff should then be confined in the internal structures both in the phase of implosion as well as during their formation and transformation. In shots with puffing deuterium, the evolution of instabilities in the plasma column was suppressed. The deuterium plasma has a higher conductance and better ability to form expressive and dense plasmoids and to transport the internal current in comparison with neon plasma. Neutrons were produced both at the initial phase of stagnation, as well as at a later time at the evolution of the constrictions and dense plasmoids.

  15. Basic concept for an accelerator-driven subcritical system to be used as a long-pulse neutron source for Condensed Matter research

    NASA Astrophysics Data System (ADS)

    Vivanco, R.; Ghiglino, A.; de Vicente, J. P.; Sordo, F.; Terrón, S.; Magán, M.; Perlado, J. M.; Bermejo, F. J.

    2014-12-01

    A model for an accelerator-driven subcritical system to be operated as a source of cold neutrons for Condensed Matter research is developed at the conceptual level. Its baseline layout relies upon proven accelerator, spalattion target and fuel array technologies, and consists in a proton accelerator able to deliver some 67.5 mA of proton beam with kinetic energy 0.6 GeV, a pulse length of 2.86 ms, and repetition rate of 14 Hz. The particle beam hits a target of conventional design that is surrounded by a multiplicative core made of fissile/fertile material, composed by a subcritical array of fuel bars made of aluminium Cermet cooled by light water poisoned with boric acid. Relatively low enriched uranium is chosen as fissile material. An optimisation of several parameters is carried out, using as components of the objective function several characteristics pertaining the cold neutron pulse. The results show that the optimal device will deliver up to 80% of the cold neutron flux expected for some of the ongoing projects using a significantly lower proton beam power than that managed in such projects. The total power developed within the core rises up to 22.8 MW, and the criticality range shifts to a final keff value of around 0.9 after the 50 days cycle.

  16. Demonstration of two-beam acceleration and 30 GHz power production in the CLIC Test Facility

    SciTech Connect

    Bossart, R.; Braun, H. H.; Carron, G.; Chanudet, M.; Chautard, F.; Delahaye, J. P.; Godot, J. C.; Hutchins, S.; Martinez, C.; Suberlucq, G.; Tenenbaum, P.; Thorndahl, L.; Trautner, H.; Valentini, M.; Wilson, I.; Wuensch, W.

    1999-05-07

    The Compact Linear Collider (CLIC) Test Facility (CTF II) at CERN has recently demonstrated Two-Beam power production and acceleration at 30 GHz. With 41 MW of 30 GHz power produced in 14 ns pulses at a repetition rate of 5 Hz, the main beam has been accelerated by 28 MeV. The 30 GHz RF power is extracted in low impedance decelerating structures from a low-energy, high-current 'drive beam' which runs parallel to the main beam. The average current in the drive-beam train is 25 A, while the peak current exceeds 2 kA. Crosschecks between measured drive-beam charge, 30 GHz power and main-beam energy gain are in good agreement. In this paper, some relevant experimental and technical issues on drive-beam generation, two-beam power production and acceleration are presented.

  17. Scientific and engineering services for the LANCE/ER accelerator production of tritium (APT) project

    SciTech Connect

    1994-12-05

    The APT project office is conducting a preconceptual design study for an accelerator driven concept to produce tritium. The facility will require new technology in many areas, since the scale of this accelerator is significantly larger then any in operation to date. The facility is composed of four subsystems: accelerator, target & blanket, balance of plant, and tritium purification system (TPS). New physics realms will be entered in order for the concept to be feasible; for example, extremely high energy levels of the entering protons that induce (multiplicative) spallation of the neutrons from the high Z target will occur. These are complex and require advance codes (MCNP) to predict the physics interactions and as well as deleterious material effects in the surrounding structures. Other issues include component cooling and complex thermal-hydraulics effects within the blanket and the beam {open_quotes}window.{close_quotes} In order to support a DOE mandated fast ROD schedule, Los Alamos APT staff will be provided with senior, engineering technical support staff with direct APT technology experience and whom are {open_quotes}on site{close_quotes}. This report contains resumes of the staff.

  18. Accelerator measurement of NaI response to medium energy neutrons and application to a satellite-borne spectrometer

    NASA Technical Reports Server (NTRS)

    Dunphy, P. P.; Chupp, E. L.; Popecki, M.; Forrest, D. J.; Lopiano, D.; Shima, T.; Spinka, H.; Glass, G.; Burleson, G.; Beddo, M.

    1992-01-01

    We report on the response of a prototype detector to medium energy neutrons. The neutrons were produced by n-p scattering of a neutron beam on a hydrogen target. The measurements provide unique data on the efficiency and response of large NaI scintillators to neutrons in the energy range 36-709 MeV. We apply the results to the high-energy mode of the Gamma-Ray Spectrometer (GRS) on the Solar Maximum Mission satellite by estimating its efficiency for neutron detection. This estimate is compared to earlier Monte Carlo calculations of the GRS efficiency.

  19. Evaluation of accelerated aolvent extractor (ASE 350) on assay of fats from food products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extraction of analytes of interest from solid and semisolid samples using liquid solvents is a common practice for most assay procedures. A systematic evaluation of the newly developed accelerated solvent system (ASE 350) for the estimation of fat from different food products (salad dressing, mayonn...

  20. Numerical simulation of gamma ray and neutron production on lunar surface using MCNPX code

    NASA Astrophysics Data System (ADS)

    Kim, Kyeong Ja

    The production of gamma ray and neutron on various planetary surfaces has been investigated for a few decades by remote sensing techniques. The production of these radiations is due to the nuclear reactions between incoming cosmic rays (i.e. galactic cosmic rays and solar cosmic rays) and planetary materials. In the case of the Moon, not like Mars, returned samples from the previous lunar missions provide us much more realistic parameters in understanding of lunar surface composition although it varies a lot. These constraints provide us restricted settings of parameters for model calculations toward the understanding radiation environment. Recent SELENE (KAGUYA) Gamma Ray spectrometer provides elemental lunar surface maps using major important gamma ray lines, such as Fe, Si, Al, U, Th, Ti, etc toward understanding of the evolution of the lunar surfaces. The effect of size or sub-layered soil deposit in the production of gamma rays and neutrons can be effectively understood using model calculations. Our Monte Carlo N-Particle eXtended (MCNPX) generated provides the gamma ray and neutron productions for various soil settings. Our study demonstrates the gamma ray and neutron production on lunar surfaces of various lunar surface soil settings using numerical simulation of MCNPX.

  1. Spallator - accelerator breeder

    SciTech Connect

    Steinberg, M.

    1985-01-01

    The concept involves the use of spallation neutrons produced by interaction of a high energy proton (1 to 2 GeV) from a linear accelerator (LINAC) with a heavy metal target (uranium). The principal spallator concept is based on generating fissile fuel for use in LWR nuclear power plants. The spallator functions in conjunction with a reprocessing plant to regenerate and produce the Pu-239 or U-233 for fabrication into fresh LWR reactor fuel elements. Advances in proton accelerator technology has provided a solid base for predicting performance and optimizing the design of a reliable, continuous wave, high-current LINAC required by a fissile fuel production machine.

  2. Promises and Challenges of Two-Step Targets for Production of Neutron-rich RIBs

    SciTech Connect

    Talbert, W.L.; Drake, D.M.; Hsu, H.-H.; Wilson, M.T.

    2003-08-26

    Development of a prototype two-step target to produce neutron-rich RIBs is presented, with particular emphasis on thermal analysis under high-power operation. The two-step target is an attractive concept for production of fission-product activities without interference by high-energy spallation reactions which occur in direct production targets. In this concept, a high-energy production beam interacts with a primary target of refractory metal, depositing beam energy in the primary target and producing low-energy neutrons that cause fissions in a surrounding secondary target of mixed UC2 and excess C. Thermal analysis of the composite target presents challenges in cooling the primary target while maintaining the secondary target at temperatures suitable for release of the fission products. The effects of fission energy deposition in the secondary target are discussed, along with the complexities resulting from the thermally insulating character of the secondary target material.

  3. CR-39 detector based thermal neutron flux measurements, in the photo neutron project

    NASA Astrophysics Data System (ADS)

    Mameli, A.; Greco, F.; Fidanzio, A.; Fusco, V.; Cilla, S.; D'Onofrio, G.; Grimaldi, L.; Augelli, B. G.; Giannini, G.; Bevilacqua, R.; Totaro, P.; Tommasino, L.; Azario, L.; Piermattei, A.

    2008-08-01

    PhoNeS (photo neutron source) is a project aimed at the production and moderation of neutrons by exploiting high energy linear accelerators, currently used in radiotherapy. A feasibility study has been carried out with the scope in mind to use the high energy photon beams from these accelerators for the production of neutrons suitable for boron neutron capture therapy (BNCT). Within these investigations, it was necessary to carry out preliminary measurements of the thermal neutron component of neutron spectra, produced by the photo-conversion of X-ray radiotherapy beams supplied by three LinAcs: 15 MV, 18 MV and 23 MV. To this end, a simple passive thermal neutron detector has been used which consists of a CR-39 track detector facing a new type of boron-loaded radiator. Once calibrated, this passive detector has been used for the measurement of both the thermal neutron component and the cadmium ratio of different neutron spectra. In addition, bubble detectors with a response highly sensitive to thermal neutrons have also been used. Both thermal neutron detectors are simple to use, very compact and totally insensitive to low-ionizing radiation such as electrons and X-rays. The resultant thermal neutron flux was above 10 6 n/cm 2s and the cadmium ratio was no greater than 15 for the first attempt of photo-conversion of X-ray radiotherapy beams.

  4. Neutron production and implosion characteristics of a deuterium gas-puff Z pinch

    SciTech Connect

    Coverdale, C. A.; Deeney, C.; Velikovich, A. L.; Clark, R. W.; Chong, Y. K.; Davis, J.; Chittenden, J.; Ruiz, C. L.; Cooper, G. W.; Nelson, A. J.; Franklin, J.; LePell, P. D.; Apruzese, J. P.; Levine, J.; Banister, J.; Qi, N.

    2007-02-15

    Experiments on the Z accelerator with deuterium gas puff implosions have produced up to 3.9x10{sup 13} ({+-}20%) neutrons at 2.34 MeV ({+-}0.10 MeV). Experimentally, the mechanism for generating these neutrons has not been definitively identified through isotropy measurements, but activation diagnostics suggest multiple mechanisms may be responsible. One-, two-, and three-dimensional magnetohydrodynamic (MHD) calculations have indicated that thermonuclear outputs from Z could be expected to be in the (0.3-1.0)x10{sup 14} range. X-ray diagnostics of plasma conditions, fielded to look at dopant materials in the deuterium, have shown that the stagnated deuterium plasma achieved electron temperatures of 2.2 keV and ion densities of 2x10{sup 20} cm{sup -3}, in agreement with the MHD calculations.

  5. Production of neutrons up to 18 MeV in high-intensity, short-pulse laser matter interactions

    SciTech Connect

    Higginson, D. P.; McNaney, J. M.; Swift, D. C.; Mackinnon, A. J.; Patel, P. K.; Petrov, G. M.; Davis, J.; Frenje, J. A.; Jarrott, L. C.; Tynan, G.; Beg, F. N.; Kodama, R.; Nakamura, H.; Lancaster, K. L.

    2011-10-15

    The generation of high-energy neutrons using laser-accelerated ions is demonstrated experimentally using the Titan laser with 360 J of laser energy in a 9 ps pulse. In this technique, a short-pulse, high-energy laser accelerates deuterons from a CD{sub 2} foil. These are incident on a LiF foil and subsequently create high energy neutrons through the {sup 7}Li(d,xn) nuclear reaction (Q = 15 MeV). Radiochromic film and a Thomson parabola ion-spectrometer were used to diagnose the laser accelerated deuterons and protons. Conversion efficiency into protons was 0.5%, an order of magnitude greater than into deuterons. Maximum neutron energy was shown to be angularly dependent with up to 18 MeV neutrons observed in the forward direction using neutron time-of-flight spectrometry. Absolutely calibrated CR-39 detected spectrally integrated neutron fluence of up to 8 x 10{sup 8} n sr{sup -1} in the forward direction.

  6. High-power liquid-lithium jet target for neutron production.

    PubMed

    Halfon, S; Arenshtam, A; Kijel, D; Paul, M; Berkovits, D; Eliyahu, I; Feinberg, G; Friedman, M; Hazenshprung, N; Mardor, I; Nagler, A; Shimel, G; Tessler, M; Silverman, I

    2013-12-01

    A compact liquid-lithium target (LiLiT) was built and tested with a high-power electron gun at the Soreq Nuclear Research Center. The lithium target, to be bombarded by the high-intensity proton beam of the Soreq Applied Research Accelerator Facility (SARAF), will constitute an intense source of neutrons produced by the (7)Li(p,n)(7)Be reaction for nuclear astrophysics research and as a pilot setup for accelerator-based Boron Neutron Capture Therapy. The liquid-lithium jet target acts both as neutron-producing target and beam dump by removing the beam thermal power (>5 kW, >1 MW/cm(3)) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the (7)Li(p,n) neutron yield, energy distribution, and angular distribution. Liquid lithium is circulated through the target loop at ~200 °C and generates a stable 1.5 mm-thick film flowing at a velocity up to 7 m/s onto a concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power areal densities of >4 kW/cm(2) and volume power density of ~2 MW/cm(3) at a lithium flow of ~4 m/s while maintaining stable temperature and vacuum conditions. The LiLiT setup is presently in online commissioning stage for high-intensity proton beam irradiation (1.91-2.5 MeV, 1-2 mA) at SARAF. PMID:24387433

  7. High-power liquid-lithium jet target for neutron production

    NASA Astrophysics Data System (ADS)

    Halfon, S.; Arenshtam, A.; Kijel, D.; Paul, M.; Berkovits, D.; Eliyahu, I.; Feinberg, G.; Friedman, M.; Hazenshprung, N.; Mardor, I.; Nagler, A.; Shimel, G.; Tessler, M.; Silverman, I.

    2013-12-01

    A compact liquid-lithium target (LiLiT) was built and tested with a high-power electron gun at the Soreq Nuclear Research Center. The lithium target, to be bombarded by the high-intensity proton beam of the Soreq Applied Research Accelerator Facility (SARAF), will constitute an intense source of neutrons produced by the 7Li(p,n)7Be reaction for nuclear astrophysics research and as a pilot setup for accelerator-based Boron Neutron Capture Therapy. The liquid-lithium jet target acts both as neutron-producing target and beam dump by removing the beam thermal power (>5 kW, >1 MW/cm3) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the 7Li(p,n) neutron yield, energy distribution, and angular distribution. Liquid lithium is circulated through the target loop at ˜200 °C and generates a stable 1.5 mm-thick film flowing at a velocity up to 7 m/s onto a concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power areal densities of >4 kW/cm2 and volume power density of ˜2 MW/cm3 at a lithium flow of ˜4 m/s while maintaining stable temperature and vacuum conditions. The LiLiT setup is presently in online commissioning stage for high-intensity proton beam irradiation (1.91-2.5 MeV, 1-2 mA) at SARAF.

  8. High-power liquid-lithium jet target for neutron production

    SciTech Connect

    Halfon, S.; Feinberg, G.; Arenshtam, A.; Kijel, D.; Berkovits, D.; Eliyahu, I.; Hazenshprung, N.; Mardor, I.; Nagler, A.; Shimel, G.; Silverman, I.; Paul, M.; Friedman, M.; Tessler, M.

    2013-12-15

    A compact liquid-lithium target (LiLiT) was built and tested with a high-power electron gun at the Soreq Nuclear Research Center. The lithium target, to be bombarded by the high-intensity proton beam of the Soreq Applied Research Accelerator Facility (SARAF), will constitute an intense source of neutrons produced by the {sup 7}Li(p,n){sup 7}Be reaction for nuclear astrophysics research and as a pilot setup for accelerator-based Boron Neutron Capture Therapy. The liquid-lithium jet target acts both as neutron-producing target and beam dump by removing the beam thermal power (>5 kW, >1 MW/cm{sup 3}) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the {sup 7}Li(p,n) neutron yield, energy distribution, and angular distribution. Liquid lithium is circulated through the target loop at ∼200 °C and generates a stable 1.5 mm-thick film flowing at a velocity up to 7 m/s onto a concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power areal densities of >4 kW/cm{sup 2} and volume power density of ∼2 MW/cm{sup 3} at a lithium flow of ∼4 m/s while maintaining stable temperature and vacuum conditions. The LiLiT setup is presently in online commissioning stage for high-intensity proton beam irradiation (1.91–2.5 MeV, 1–2 mA) at SARAF.

  9. Production and test results of SC 3.9-GHz accelerating cavity at Fermilab

    SciTech Connect

    Khabiboulline, Timergali; Cooper, Charlie; Edwards, Helen; Foley, Mike; Gonin, Ivan; Mitchell, Donald; Olis, D.; Rowe, Allan; Salman, Tariq; Solyak, Nikolay; /Fermilab

    2006-08-01

    The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve beam performances for TTF-FEL facility. In the frame of collaboration Fermilab will provide DESY with a cryomodule containing a string of four cavities. In addition, a second cryomodule with one cavity will be fabricated for installation in the Fermilab photo-injector, which will be upgraded for the ILC accelerator test facility. In this paper we discuss the status of the cavity and coupler production and the first result of cavity tests. It is hoped that this project will be completed during the first half of 2007 and the cryomodule delivered to DESY in this time span.

  10. Hexagonal boron nitride thin film thermal neutron detectors with high energy resolution of the reaction products

    NASA Astrophysics Data System (ADS)

    Doan, T. C.; Majety, S.; Grenadier, S.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2015-05-01

    Hexagonal boron nitride (h-BN) is highly promising for solid-state thermal neutron detector applications due to its many outstanding physical properties, especially its very large thermal neutron capture cross-section (~3840 barns for 10B), which is several orders of magnitude larger than those of most other isotopes. The focus of the present work is to carry out studies on h-BN thin film and detector properties to lay the foundation for the development of a direct-conversion solid-state thermal neutron detector with high sensitivity. The measured carrier mobility-lifetime (μτ) product of h-BN thin films grown on sapphire substrates is 2.83×10-7 cm2/V for electrons and holes, which is comparable to the value of about 10-7 cm2/V for GaN thin films grown on sapphire. Detectors based on h-BN thin films were fabricated and the nuclear reaction product pulse height spectra were measured. Under a bias of 20 V, very narrow individual peaks corresponding to the reaction product energies of α and Li particles as well as the sum peaks have been clearly resolved in the pulse height spectrum for the first time by a B-based direct-conversion semiconductor neutron detector. Our results indicate that h-BN thin film detectors possess unique advantages including small size, low weight, portability, low voltage operation and high energy resolution of specific reaction products.

  11. Study on the impact of pair production interaction on D-T controllable neutron density logging.

    PubMed

    Yu, Huawei; Zhang, Li; Hou, Boran

    2016-05-01

    This paper considers the effect of pair production on the precision of D-T controllable neutron source density logging. Firstly, the principle of the traditional density logging and pulsed neutron density logging are analyzed and then gamma ray cross sections as a function of energy for various minerals are compared. In addition, the advantageous areas of Compton scattering and pair production interactions on high-energy gamma ray pulse height spectrum and the errors of a controllable source density measurement are studied using a Monte Carlo simulation method. The results indicate that density logging mainly utilizes the Compton scattering of gamma rays, while the attenuation of neutron induced gamma rays and the precision of neutron gamma density measurements are affected by pair production interactions, particularly in the gamma rays with energy higher than 2MeV. By selecting 0.2-2MeV energy range and performing proper lithology correction, the effect of pair production can be eliminated effectively and the density measurement error can be rendered close to the precision of chemical source density logging. PMID:26945102

  12. Production of heavy and superheavy neutron-rich nuclei in transfer reactions

    SciTech Connect

    Zagrebaev, V. I.; Greiner, Walter

    2011-04-15

    The problem of production and study of heavy neutron-rich nuclei has been intensively discussed during recent years. Many reasons arouse a great interest in this problem. The present limits of the upper part of the nuclear map are very close to the {beta} stability line while the unexplored area of heavy neutron-rich nuclides (also those located along the neutron closed shell N=126 to the right-hand side of the stability line) is extremely important for nuclear astrophysic investigations and, in particular, for the understanding of the r process of astrophysical nucleogenesis. For elements with Z>100 only neutron deficient isotopes (located to the left of the stability line) have been synthesized so far. The 'northeast' area of the nuclear map can be reached neither in fusion-fission reactions nor in fragmentation processes widely used nowadays for the production of new nuclei. Multinucleon transfer processes in near barrier collisions of heavy (and very heavy, U-like) ions seem to be the only reaction mechanism allowing us to produce and explore neutron-rich heavy nuclei including those located at the superheavy island of stability. In this paper several transfer reactions for different projectile-target combinations are studied in detail. Besides the predictions for the cross sections of such processes, we also analyze the angular and energy distributions of primary and survived reaction products in the laboratory frame. These results, as well as predicted excitation functions for the yields of neutron-rich superheavy isotopes, might be useful for the design of appropriate experimental equipment and for carrying out experiments of such kind.

  13. Point defect production and annihilation in neutron-irradiated zirconium

    SciTech Connect

    MacEwen, S.R.; Zee, R.H.; Birtcher, R.C.; Abromeit, C.

    1984-05-01

    High-purity Zr has been irradiated to a dose of 2.2 x 10/sup 21/ n/m/sup 2/ (E < 0.1 MeV) using the pulsed spallation source at IPNS. Electrical resistivity was monitored continuously during irradiation. The saturation resistivity, found from a linear extrapolation of the damage-rate curve between four and five n..cap omega...m. However, comparison with data from the literature shows that the normalized damage-rate curves from five experiments at different temperatures (less than or equal to 77 K) and with different neutron spectra, all fall on the same common curve. A saturation resistivity of 100 n..cap omega...m is found from the high-dose, linear part of this curve. A spontaneous recombination volume in the range 280 to 400 atomic volumes is found using the theory of Dettmann, Leibfried and Schroeder and the saturation resistivity of 100 n..cap omega...m. Post-irradiation annealing has been done up to 300 K using stepped, isochronal anneals. The recovery spectrum is in reasonable agreement with previous work, showing a large peak near 100 K, and two smaller peaks at 160 K and 250 K.

  14. Accelerated hydrolysis of substituted cellulose for potential biofuel production: kinetic study and modeling.

    PubMed

    Mu, Bingnan; Xu, Helan; Yang, Yiqi

    2015-11-01

    In this work, kinetics of substitution accelerated cellulose hydrolysis with multiple reaction stages was investigated to lay foundation for mechanism study and molecular design of substituting compounds. High-efficiency hydrolysis of cellulose is critical for cellulose-based bioethanol production. It is known that, substitution could substantially decrease activation energy and increase reaction rate of acidic hydrolysis of glycosidic bonds in cellulose. However, reaction kinetics and mechanism of the accelerated hydrolysis were not fully revealed. In this research, it was proved that substitution therefore accelerated hydrolysis only occurred in amorphous regions of cellulose fibers, and was a process with multiple reaction stages. With molar ratio of substitution less than 1%, the overall hydrolysis rate could be increased for around 10 times. We also quantified the relationship between the hydrolysis rate of individual reaction stage and its major influences, including molar ratio of substitution, activation energy of acidic hydrolysis, pH and temperature. PMID:26253917

  15. METHOD OF INITIATING AND SUSTAINING AN ENERGETIC PLASMA FOR NEUTRON PRODUCTION

    DOEpatents

    Bell, P.R.; Mackin, R.J. Jr.; Simon, A.

    1961-08-22

    A method for producing an energetic plasma for neutron production and for faeling this plasma once it is formed is described. The plasma is initially fonmed as set forth in U. S. Patent No. 2,969,308. After the plasma is formed, cold neutral particles with an energy of at least 1 Kev are injected in a radial directinn and transverse to the axis of the device. These cold particles are substituted for the molecular ion injection and are used for fueling the plasma device on a continuous regulated basis in order to maintain a reaction temperature of about 60 Kev for producing neutrons. (AE C)

  16. Fission Product Decay Heat Calculations for Neutron Fission of 232Th

    NASA Astrophysics Data System (ADS)

    Son, P. N.; Hai, N. X.

    2016-06-01

    Precise information on the decay heat from fission products following times after a fission reaction is necessary for safety designs and operations of nuclear-power reactors, fuel storage, transport flasks, and for spent fuel management and processing. In this study, the timing distributions of fission products' concentrations and their integrated decay heat as function of time following a fast neutron fission reaction of 232Th were exactly calculated by the numerical method with using the DHP code.

  17. Acceleration of Fe-silicate mineral dissolution for CO2 sequestration via microbial siderophore production

    NASA Astrophysics Data System (ADS)

    Torres, M. A.; Nealson, K. H.; West, A.

    2013-12-01

    While the dissolution of silicate minerals will ultimately neutralize anthropogenic CO2 emissions, the slow natural timescale of this process limits its ability to mitigate any of the societal impacts of high atmospheric pCO2. As a result, much research has been focused on developing ways to significantly accelerate silicate mineral dissolution rates. Harnessing the effects of microbial activity is one particularly attractive strategy because research has shown that microbes can appreciably accelerate mineral dissolution rates and they require little external energy input. At present, one major hurdle in the development of microbe-based CO2 sequestration techniques is the observation that bacteria only accelerate dissolution rates under particular culturing conditions. In this work, natural and genetic mutant strains of the bacterial genera Shewanella, Pseudomonas, and Marinobacter are used to identify the geochemical and genetic factors that underlie the 'accelerated-weathering phenotype' in order to support the development of microbe-based CO2 sequestration techniques using olivine as a model mineral. Preliminary results suggest that microbial siderophore production at circum-neutral pH results in significantly accelerated olivine dissolution rates.

  18. Accelerator mass spectrometry of 63Ni at the Munich Tandem Laboratory for estimating fast neutron fluences from the Hiroshima atomic bomb.

    PubMed

    Rühm, W; Knie, K; Rugel, G; Marchetti, A A; Faestermann, T; Wallner, C; McAninch, J E; Straume, T; Korschinek, G

    2000-10-01

    After the release of the present dosimetry system DS86 in 1987, measurements have shown that DS86 may substantially underestimate thermal neutron fluences at large distances (>1,000 m) from the hypocenter in Hiroshima. This discrepancy casts doubts on the DS86 neutron source term and, consequently, the survivors' estimated neutron doses. However, the doses were caused mainly by fast neutrons. To determine retrospectively fast neutron fluences in Hiroshima, the reaction 63Cu(n, p)63Ni can be used, if adequate copper samples can be found. Measuring 63Ni (half life 100 y) in Hiroshima samples requires a very sensitive technique, such as accelerator mass spectrometry (AMS), because of the relatively small amounts of 63Ni expected (approximately 10(5)-10(6) atoms per gram of copper). Experiments performed at Lawrence Livermore National Laboratory have demonstrated in 1996 that AMS can be used to measure 63Ni in Hiroshima copper samples. Subsequently, a collaboration was established with the Technical University of Munich in view of its potential to perform more sensitive measurements of 63Ni than the Livermore facility and in the interest of interlaboratory validation. This paper presents the progress made at the Munich facility in the measurement of 63Ni by AMS. The Munich accelerator mass spectrometry facility is a combination of a high energy tandem accelerator and a detection system featuring a gas-filled magnet. It is designed for high sensitivity measurements of long-lived radioisotopes. Optimization of the ion source setup has further improved the sensitivity for 63Ni by reducing the background level of the 63Cu isobar interference by about two orders of magnitude. Current background levels correspond to a ratio of 63Ni/Ni<2x10(-14) and suggest that, with adequate copper samples, the assessment of fast neutron fluences in Hiroshima and Nagasaki is possible for ground distances of up to 1500 m, and--under favorable conditions--even beyond. To demonstrate this

  19. Neutron production using a pyroelectric driven target coupled with a gated field ionization source

    SciTech Connect

    Ellsworth, J. L.; Tang, V.; Falabella, S.; Naranjo, B.; Putterman, S.

    2013-04-19

    A palm sized, portable neutron source would be useful for widespread implementation of detection systems for shielded, special nuclear material. We present progress towards the development of the components for an ultracompact neutron generator using a pulsed, meso-scale field ionization source, a deuterated (or tritiated) titanium target driven by a negative high voltage lithium tantalate crystal. Neutron production from integrated tests using an ion source with a single, biased tungsten tip and a 3 Multiplication-Sign 1 cm, vacuum insulated crystal with a plastic deuterated target are presented. Component testing of the ion source with a single tip produces up to 3 nA of current. Dielectric insulation of the lithium tantalate crystals appears to reduce flashover, which should improve the robustness. The field emission losses from a 3 cm diameter crystal with a plastic target and 6 cm diameter crystal with a metal target are compared.

  20. Proliferation Potential of Accelerator-Drive Systems: Feasibility Calculations

    SciTech Connect

    Riendeau, C.D.; Moses, D.L.; Olson, A.P.

    1998-11-01

    Accelerator-driven systems for fissile materials production have been proposed and studied since the early 1950s. Recent advances in beam power levels for small accelerators have raised the possibility that such use could be feasible for a potential proliferator. The objective of this study is to review the state of technology development for accelerator-driven spallation neutron sources and subcritical reactors. Energy and power requirements were calculated for a proton accelerator-driven neutron spallation source and subcritical reactors to produce a significant amount of fissile material--plutonium.

  1. MANTA. An Integral Reactor Physics Experiment to Infer the Neutron Capture Cross Sections of Actinides and Fission Products in Fast and Epithermal Spectra

    SciTech Connect

    Youinou, Gilles Jean-Michel

    2015-10-01

    Neutron cross-sections characterize the way neutrons interact with matter. They are essential to most nuclear engineering projects and, even though theoretical progress has been made as far as the predictability of neutron cross-section models, measurements are still indispensable to meet tight design requirements for reduced uncertainties. Within the field of fission reactor technology, one can identify the following specializations that rely on the availability of accurate neutron cross-sections: (1) fission reactor design, (2) nuclear fuel cycles, (3) nuclear safety, (4) nuclear safeguards, (5) reactor monitoring and neutron fluence determination and (6) waste disposal and transmutation. In particular, the assessment of advanced fuel cycles requires an extensive knowledge of transuranics cross sections. Plutonium isotopes, but also americium, curium and up to californium isotope data are required with a small uncertainty in order to optimize significant features of the fuel cycle that have an impact on feasibility studies (e.g. neutron doses at fuel fabrication, decay heat in a repository, etc.). Different techniques are available to determine neutron cross sections experimentally, with the common denominator that a source of neutrons is necessary. It can either come from an accelerator that produces neutrons as a result of interactions between charged particles and a target, or it can come from a nuclear reactor. When the measurements are performed with an accelerator, they are referred to as differential since the analysis of the data provides the cross-sections for different discrete energies, i.e. σ(Ei), and for the diffusion cross sections for different discrete angles. Another approach is to irradiate a very pure sample in a test reactor such as the Advanced Test Reactor (ATR) at INL and, after a given time, determine the amount of the different transmutation products. The precise characterization of the nuclide densities before and after

  2. Neutron production by fast protons from ultraintense laser-plasma interactions

    SciTech Connect

    Yang, J.M.; McKenna, P.; Ledingham, K.W.D.; McCanny, T.; Robson, L.; Shimizu, S.; Singhal, R.P.; Wei, M.S.; Krushelnick, K.; Clarke, R.J.; Neely, D.; Norreys, P.A.

    2004-12-01

    Tens of MeV proton beams have been generated by interactions of the VULCAN petawatt laser with foil targets and used to induce nuclear reactions in zinc and boron samples. The numbers of {sup 11}C, {sup 66}Ga, {sup 67}Ga, {sup 68}Ga, {sup 61}Cu, {sup 62}Zn, {sup 63}Zn, and {sup 69m}Zn nuclei have been measured and used to determine the proton energy spectrum. It is known that (p,n) reactions provide an important method for producing neutron sources and in the present experiment up to {approx}10{sup 9} neutrons sr{sup -1} have been generated via {sup 11}B(p,n){sup 11}C reactions. Using experimentally determined proton energy spectra, the production of neutrons via (p,n) reactions in various targets has been simulated, to quantify neutron pulse intensities and energy spectra. It has been shown that as high as 4x10{sup 9} neutrons sr{sup -1} per laser pulse can be generated via {sup 7}Li(p,n){sup 7}B reactions using the present VULCAN petawatt laser-pulse conditions.

  3. Science opportunities at high power accelerators like APT

    SciTech Connect

    Browne, J.C.

    1996-12-31

    This paper presents applications of high power RF proton linear accelerators to several fields. Radioisotope production is an area in which linacs have already provided new isotopes for use in medical and industrial applications. A new type of spallation neutron source, called a long-pulse spallation source (LPSS), is discussed for application to neutron scattering and to the production and use of ultra-cold neutrons (UCN). The concept of an accelerator-driven, transmutation of nuclear waste system, based on high power RF linac technology, is presented along with its impact on spent nuclear fuels.

  4. The study of neutron-rich nuclei production in the region of the closed shell N=126 in the multi-nucleon transfer reaction 136Xe+208Pb

    NASA Astrophysics Data System (ADS)

    Novikov, K.; Harca, I. M.; Kozulin, E. M.; Dmitriev, S.; Itkis, J.; Knyazheva, G.; Loktev, T.; Corradi, L.; Valiente-Dobon, J.; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Vardaci, E.; Quero, D.; Montagnoli, G.; Scarlassara, F.; Strano, E.; Pollarolo, G.; Piot, J.; Mijatović, T.; Szilner, S.; Ackermann, D.; Chubarian, G.; Trzaska, W. H.

    2016-04-01

    The unexplored area of heavy neutron rich nuclei is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleogenesis. For the production of heavy neutron rich nuclei located along the neutron closed shell N=126 (probably the last "waiting point" in the r-process of nucleosynthesis) the low-energy multi-nucleon transfer reaction 136Xe+208Pb at Elab=870MeV was explored. Due to the stabilizing effect of the closed neutron shells in both nuclei, N=82 and N=126, and the rather favorable proton transfer from lead to xenon, the light fragments formed in this process are well bound and the Q-value of the reaction is nearly zero. Measurements were performed with the PRISMA spectrometer in coincidence with an additional time-of-flight (ToF) arm on the +20 beam line of the PIAVE-ALPI accelerator in Legnaro, Italy. The PRISMA spectrometer allows identification of the A, Z and velocity of the projectile-like fragments (PLF), while the second arm gives access to the target-like fragments (TLF). Details on the experimental setup and preliminary results are reported.

  5. Neutron Imaging Developments at LANSCE

    SciTech Connect

    Nelson, Ronald Owen; Hunter, James F.; Schirato, Richard C.; Vogel, Sven C.; Swift, Alicia L.; Ickes, Timothy Lee; Ward, William Carl; Losko, Adrian Simon; Tremsin, Anton; Sevanto, Sanna Annika; Espy, Michelle A.; Dickman, Lee Thoresen; Malone, Michael

    2015-10-29

    Thermal, epithermal, and high-energy neutrons are available from two spallation sources at the 800 MeV proton accelerator. Improvements in detectors and computing have enabled new capabilities that use the pulsed beam properties at LANSCE; these include amorphous Si (aSi) detectors, intensified charge-coupled device cameras, and micro-channel plates. Applications include water flow in living specimens, inclusions and fission products in uranium oxide, and high-energy neutron imaging using an aSi flat panel with ZnS(Ag) scintillator screen. images of a metal/plastic cylinder from photons, low-energy and high-energy neutrons are compared.

  6. Production of heavy neutron-rich nuclei in transfer reactions within the dinuclear system model

    NASA Astrophysics Data System (ADS)

    Zhu, Long; Feng, Zhao-Qing; Zhang, Feng-Shou

    2015-08-01

    The dynamics of nucleon transfer processes in heavy-ion collisions is investigated within the dinuclear system model. The production cross sections of nuclei in the reactions 136Xe+208Pb and 238U+248Cm are calculated, and the calculations are in good agreement with the experimental data. The transfer cross sections for the 58Ni+208Pb reaction are calculated and compared with the experimental data. We predict the production cross sections of neutron-rich nuclei 165-168 Eu, 169-173 Tb, 173-178 Ho, and 181-185Yb based on the reaction 176Yb+238U. It can be seen that the production cross sections of the neutron-rich nuclei 165Eu, 169Tb, 173Ho, and 181Yb are 2.84 μb, 6.90 μb, 46.24 μb, and 53.61 μb, respectively, which could be synthesized in experiment.

  7. Light-ion production in the interaction of 96 MeV neutrons with oxygen

    SciTech Connect

    Tippawan, U.; Pomp, S.; Atac, A.; Blomgren, J.; Dangtip, S.; Hildebrand, A.; Johansson, C.; Klug, J.; Mermod, P.; Oesterlund, M.; Bergenwall, B.; Nilsson, L.; Olsson, N.; Prokofiev, A.V.; Nadel-Turonski, P.; Corcalciuc, V.; Koning, A.J.

    2006-03-15

    Double-differential cross sections are reported for light-ion (p, d, t, {sup 3}He, and {alpha}) production in oxygen induced by 96 MeV neutrons. Energy spectra are measured at eight laboratory angles from 20 degree sign to 160 degree sign in steps of 20 degree sign . Procedures for data taking and data reduction are presented. Deduced energy-differential and production cross sections are reported. Experimental cross sections are compared to theoretical reaction model calculations and experimental data at lower neutron energies in the literature. The measured proton data agree reasonably well with the results of the model calculations, whereas the agreement for the other particles is less convincing. The measured production cross sections for protons, deuterons, tritons, and {alpha} particles support the trends suggested by data at lower energies.

  8. HZETRN: neutron and proton production in quasi-elastic scattering of GCR heavy-ions

    NASA Technical Reports Server (NTRS)

    Shavers, M. R.; Cucinotta, F. A.; Wilson, J. W.

    2001-01-01

    The development of transport models for radiation shielding design and evaluation has provided a series of deterministic computer codes that describe galactic cosmic radiation (GCR), solar particle events, and experimental beams at particle accelerators. These codes continue to be modified to accommodate new theory and improvements to the particle interaction database (Cucinotta et al., 1994, NASA Technical Paper 3472, US Government Printing Office, Washington DC). The solution employed by the heavy-ion transport code HZETRN was derived with the assumption that nuclear fragments are emitted with the same velocity as the incident ion through velocity conserving nuclear interactions. This paper presents a version of the HZETRN transport code that provides a more realistic distribution of the energy of protons and neutrons emitted from GCR interactions in shields. This study shows that the expected GCR dose equivalent is lower than previously calculated for water shields that are less than 110 g cm-2 thick. Calculations of neutron energy spectra in low Earth orbit indicate substantial contributions from relativistic neutrons. c2001 Elsevier Science Ltd. All rights reseved.

  9. Adjoint acceleration of Monte Carlo simulations using SCALE: A radiation shielding evaluation of the neutron generator room at Missouri S&T

    NASA Astrophysics Data System (ADS)

    Sharma, Manish K.; Alajo, Ayodeji B.; Liu, Xin

    2015-08-01

    A deuterium-deuterium accelerator-type neutron generator was installed in the Nuclear Engineering Department at Missouri University of Science and Technology (Missouri S&T). This generator is shielded by different hydrogenated and non-hydrogenated materials to reduce the dose rates in the vicinity of the facility. In the work presented in this paper, both SCALE6 and MCNP5 radiation transport codes were used to conduct two independent simulations. The new shielding analysis tool of SCALE6-MAVRIC, with the automatic variance reduction technique of SCALE6, was utilized to estimate and compare the dose rates from the unbiased MCNP simulation. The ultimate goal of this study was to compare the computational effectiveness offered by employing the MAVRIC sequence in the modeling of the neutron generator facility at Missouri S&T.

  10. Investigation of neutron converters for production of optically stimulated luminescence (OSL) neutron dosimeters using Al 2O 3:C

    NASA Astrophysics Data System (ADS)

    Mittani, J. C. R.; da Silva, A. A. R.; Vanhavere, F.; Akselrod, M. S.; Yukihara, E. G.

    2007-07-01

    This paper presents the optically stimulated luminescence (OSL) properties of neutron dosimeters in powder and in the form of pellets prepared with a mixture of Al 2O 3:C and neutron converters. The neutron converters investigated were high density polyethylene (HDPE), lithium fluoride (LiF), lithium fluoride 95% enriched with 6Li ( 6LiF), lithium carbonate 95% enriched with 6Li ( 6Li 2CO 3), boric acid enriched with 99% of 10B (H310BO) and gadolinium oxide (Gd 2O 3). The proportion of Al 2O 3:C and neutron converter in the mixture was varied to optimize the total OSL signal and neutron sensitivity. The neutron sensitivity and dose-response were determined for the OSL dosimeters using a bare 252Cf source and compared to the response of Harshaw TLD-600 and TLD-700 dosimeters ( 6LiF:Mg,Ti and 7LiF:Mg,Ti). The results demonstrate the possibility of developing an OSL dosimeter made of Al 2O 3:C powder and neutron converter with a neutron sensitivity (defined as the ratio between the 60Co equivalent gamma dose and the reference neutron absorbed dose) and neutron-gamma discrimination comparable to the TLD-600/TLD-700 combination. It was shown that the shape of the OSL decay curves varied with the type of the neutron converter, demonstrating the influence of the energy deposition mechanism and ionization density on the OSL process in Al 2O 3:C.

  11. Investigation of Secondary Neutron Production in Large Space Vehicles for Deep Space

    NASA Technical Reports Server (NTRS)

    Rojdev, Kristina; Koontz, Steve; Reddell, Brandon; Atwell, William; Boeder, Paul

    2016-01-01

    Future NASA missions will focus on deep space and Mars surface operations with large structures necessary for transportation of crew and cargo. In addition to the challenges of manufacturing these large structures, there are added challenges from the space radiation environment and its impacts on the crew, electronics, and vehicle materials. Primary radiation from the sun (solar particle events) and from outside the solar system (galactic cosmic rays) interact with materials of the vehicle and the elements inside the vehicle. These interactions lead to the primary radiation being absorbed or producing secondary radiation (primarily neutrons). With all vehicles, the high-energy primary radiation is of most concern. However, with larger vehicles, there is more opportunity for secondary radiation production, which can be significant enough to cause concern. In a previous paper, we embarked upon our first steps toward studying neutron production from large vehicles by validating our radiation transport codes for neutron environments against flight data. The following paper will extend the previous work to focus on the deep space environment and the resulting neutron flux from large vehicles in this deep space environment.

  12. Note: Proton irradiation at kilowatt-power and neutron production from a free-surface liquid-lithium target

    NASA Astrophysics Data System (ADS)

    Halfon, S.; Arenshtam, A.; Kijel, D.; Paul, M.; Weissman, L.; Aviv, O.; Berkovits, D.; Dudovitch, O.; Eisen, Y.; Eliyahu, I.; Feinberg, G.; Haquin, G.; Hazenshprung, N.; Kreisel, A.; Mardor, I.; Shimel, G.; Shor, A.; Silverman, I.; Tessler, M.; Yungrais, Z.

    2014-05-01

    The free-surface Liquid-Lithium Target, recently developed at Soreq Applied Research Accelerator Facility (SARAF), was successfully used with a 1.9 MeV, 1.2 mA (2.3 kW) continuous-wave proton beam. Neutrons (˜2 × 1010 n/s having a peak energy of ˜27 keV) from the 7Li(p,n)7Be reaction were detected with a fission-chamber detector and by gold activation targets positioned in the forward direction. The setup is being used for nuclear astrophysics experiments to study neutron-induced reactions at stellar energies and to demonstrate the feasibility of accelerator-based boron neutron capture therapy.

  13. Note: Proton irradiation at kilowatt-power and neutron production from a free-surface liquid-lithium target

    SciTech Connect

    Halfon, S.; Feinberg, G.; Arenshtam, A.; Kijel, D.; Weissman, L.; Aviv, O.; Berkovits, D.; Dudovitch, O.; Eisen, Y.; Eliyahu, I.; Haquin, G.; Hazenshprung, N.; Kreisel, A.; Mardor, I.; Shimel, G.; Shor, A.; Silverman, I.; Yungrais, Z.; Paul, M. Tessler, M.

    2014-05-15

    The free-surface Liquid-Lithium Target, recently developed at Soreq Applied Research Accelerator Facility (SARAF), was successfully used with a 1.9 MeV, 1.2 mA (2.3 kW) continuous-wave proton beam. Neutrons (∼2 × 10{sup 10} n/s having a peak energy of ∼27 keV) from the {sup 7}Li(p,n){sup 7}Be reaction were detected with a fission-chamber detector and by gold activation targets positioned in the forward direction. The setup is being used for nuclear astrophysics experiments to study neutron-induced reactions at stellar energies and to demonstrate the feasibility of accelerator-based boron neutron capture therapy.

  14. Compact neutron generator development at LBNL

    SciTech Connect

    Reijonen, J.; English, G.; Firestone, R.; Giquel, F.; King, M.; Leung, K-N.; Sun, M.

    2003-12-31

    A wide variety of applications ranging from medical (BNCT, Boron Neutron Capture Therapy) and basic science (neutron imaging, material studies) to homeland security (explosive detection and nuclear material non-proliferation) are in need of compact, high flux neutron generators. The Plasma and Ion Source Technology Group in the Lawrence Berkeley National Laboratory is developing various neutron generators for these applications. These neutron generators employed either the D-D or the D-T fusion reaction for the neutron production. The deuterium or deuterium-tritium gas mixture is ionized in an RF-driven plasma source. The ions are then accelerated to {approx}100 keV energy using high current, high voltage DC-power supply to a target where the 2.45 MeV (for D-D reaction) or 14 MeV (for the D-T reaction) neutrons are generated. The development of two different types of neutron tubes are being discussed in this presentation, namely compact, pulsed operation neutron generators and cw, high yield neutron generators. These generators are currently operating at D-D neutron yields of 108 n/s and 109 n/s respectively. A facility, incorporating the larger neutron generator, has been constructed for Prompt Gamma Activation Analysis (PGAA) and Neutron Activation Analysis (NAA) measurements.

  15. Undergraduate Measurements of Neutron Cross Sections

    NASA Astrophysics Data System (ADS)

    Hicks, S. F.; Vanhoy, J. R.; French, A. J.; Santonil, Z. C.; Crider, B. P.; Peters, E. E.; McEllistrem, M. T.; Prados-Estévez, F. M.; Ross, T. J.; Yates, S. W.

    Undergraduate students at the University of Dallas have investigated basic properties of nuclei through γ-ray and neutron spectroscopy following neutron scattering. The former has been used primarily for nuclear structure investigations, while the latter has been used to measure neutron scattering cross sections important for fission reactor applications. A series of (n,n') and (n,n'γ) measurements have been made on 54Fe and 56Fe to determine neutron cross sections for scattering to excited levels in these nuclei. The former provides the cross sections directly and the latter are used to deduce inelastic neutron scattering cross sections by measuring the γ-ray production cross sections to states not easily resolved in neutron spectroscopy. All measurements have been completed at the University of Kentucky Accelerator Laboratory using a 7-MV Model CN Van de Graaff accelerator, along with the neutron production and neutron and γ-ray detection systems located there. Students participate in accelerator operation, experimental setup, data acquisition, and data analyses. An overview of the research program and student contributions is presented.

  16. Neutron capture production rates of cosmogenic 60Co, 59Ni and 36Cl in stony meteorites

    NASA Technical Reports Server (NTRS)

    Spergel, M. S.; Reedy, R. C.; Lazareth, O. W.; Levy, P. W.

    1986-01-01

    Results for neutron flux calculations in stony meteoroids (of various radii and compositions) and production rates for Cl-36, Ni-59, and Co-60 are reported. The Ni-59/Co-60 ratio is nearly constant with depth in most meteorites: this effect is consistent with the neutron flux and capture cross section properties. The shape of the neutron flux energy spectrum, varies little with depth in a meteorite. The size of the parent meteorite can be determined from one of its fragments, using the Ni-59/Co-60 ratios, if the parent meteorite was less than 75 g/cm(2) in radius. If the parent meteorite was larger, a lower limit on the size of the parent meteorite can be determined from a fragment. In C3 chondrites this is not possible. In stony meteorites with R less than 50 g/cm(2) the calculated Co-60 production rates (mass less than 4 kg), are below 1 atom/min g-Co. The highest Co-60 production rates occur in stony meteorites with radius about 250 g/cm(2) (1.4 m across). In meteorites with radii greater than 400 g/cm(2), the maximum Co-60 production rate occurs at a depth of about 175 g/cm(2) in L-chondrite, 125 g/cm(2) in C3 chrondrite, and 190 g/cm(2) in aubrites.

  17. Residual Nuclide Production from Iron, Lead, and Uranium by Neutron-Induced Reactions up to 180 MeV

    SciTech Connect

    Michel, R.; Glasser, W.; Herpers, U.; Schuhmacher, H.; Brede, H.J.; Dangendorf, V.; Nolte, R.; Malmborg, P.; Prokofiev, A.V.; Smirnov, A.N.; Rishkov, I.; Kollar, D.; Meulders, J.P.; Duijvestijn, M.; Koning, A.

    2005-05-24

    Within the HINDAS project, activation experiments with quasi mono-energetic neutrons were performed at UCL and TSL. Cross sections for the production of residual radionuclides were derived from the measured activities by unfolding, based on the neutron spectra inside the target stacks and starting from 'guess' excitation functions. Exemplary results are presented and are compared with theoretical calculations using the TALYS code.

  18. Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator.

    PubMed

    Chang, C-L; Hsieh, C-T; Ho, Y-C; Chen, Y-S; Lin, J-Y; Wang, J; Chen, S-Y

    2007-03-01

    Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator is investigated with a tomographic method which resolves the electron injection and acceleration processes. It is found that all the electrons in the monoenergetic electron bunch are injected at the same location in the plasma column and then accelerated with an acceleration gradient exceeding 2 GeV/cm. The injection position shifts with the position of pump-pulse focus, and no significant deceleration is observed for the monoenergetic electron bunch after it reaches the maximum energy. The results are consistent with the model of transverse wave breaking and beam loading for the injection of monoenergetic electrons. The tomographic method adds a crucial dimension to the whole array of existing diagnostics for laser beams, plasma waves, and electron beams. With this method the details of the underlying physical processes in laser-plasma interactions can be resolved and compared directly to particle-in-cell simulations. PMID:17500801

  19. Atmospheric neutrons

    NASA Technical Reports Server (NTRS)

    Korff, S. A.; Mendell, R. B.; Merker, M.; Light, E. S.; Verschell, H. J.; Sandie, W. S.

    1979-01-01

    Contributions to fast neutron measurements in the atmosphere are outlined. The results of a calculation to determine the production, distribution and final disappearance of atmospheric neutrons over the entire spectrum are presented. An attempt is made to answer questions that relate to processes such as neutron escape from the atmosphere and C-14 production. In addition, since variations of secondary neutrons can be related to variations in the primary radiation, comment on the modulation of both radiation components is made.

  20. Permafrost thawing in organic Arctic soils accelerated by ground heat production

    NASA Astrophysics Data System (ADS)

    Hollesen, Jørgen; Matthiesen, Henning; Møller, Anders Bjørn; Elberling, Bo

    2015-06-01

    Decomposition of organic carbon from thawing permafrost soils and the resulting release of carbon to the atmosphere are considered to represent a potentially critical global-scale feedback on climate change. The accompanying heat production from microbial metabolism of organic material has been recognized as a potential positive-feedback mechanism that would enhance permafrost thawing and the release of carbon. This internal heat production is poorly understood, however, and the strength of this effect remains unclear. Here, we have quantified the variability of heat production in contrasting organic permafrost soils across Greenland and tested the hypothesis that these soils produce enough heat to reach a tipping point after which internal heat production can accelerate the decomposition processes. Results show that the impact of climate changes on natural organic soils can be accelerated by microbial heat production with crucial implications for the amounts of carbon being decomposed. The same is shown to be true for organic middens with the risk of losing unique evidence of early human presence in the Arctic.

  1. The Hiroshima thermal-neutron discrepancy for (36)Cl at large distances. Part II: Natural in situ production as a source.

    PubMed

    Nolte, Eckehart; Huber, Thomas; Rühm, Werner; Kato, Kazuo; Lazarev, Vitali; Schultz, Ludolf

    2005-10-01

    For Hiroshima, a large discrepancy between calculated and measured thermal-neutron fluences had been reported in the past, for distances to the epicenter larger than about 1,000 m. To be more specific, measured (36)Cl concentrations in environmental samples from Hiroshima were too large at these distances, and the ratio of measured to calculated values reached about 70, at a distance of 1,800 m. In an attempt to identify other sources that might also produce (36)Cl in Hiroshima samples, the role of cosmic rays and of neutrons from natural terrestrial sources was investigated. Four reaction mechanisms were taken into account: spallation reactions of the nucleonic (hadronic) component of the cosmic rays on potassium (K) and calcium (Ca) in the sample material, particle emission after nuclear capture of negative muons by K and Ca, reactions of fast-muon induced electromagnetic, and hadronic showers with K and Ca, and neutron capture reactions with (35)Cl in the sample where the neutrons originate from the above three reaction mechanisms and from uranium and thorium decay. These mechanisms are physically described and mathematically quantified. It is shown that among those parameters important for the production of (36)Cl in granite, the chemical composition of the sample, the depth in the quarry where the sample had initially been taken, and the erosion rate at the site of the quarry are most important. Based on these physical, chemical, and geological parameters, (36)Cl concentrations were calculated for different types of granite that are typical for the Hiroshima area. In samples that were of these granite types and that had not been exposed to atomic bomb(A-bomb) neutrons, the (36)Cl concentration was also determined experimentally by means of accelerator mass spectrometry, and good agreement was found with the calculated values. The (36)Cl signal due to natural in situ production was also calculated in granite samples that had been exposed to A-bomb neutrons at

  2. Finite element analysis and frequency shift studies for the bridge coupler of the coupled cavity linear accelerator of the spallation neutron source.

    SciTech Connect

    Chen, Z.

    2001-01-01

    The Spallation Neutron Source (SNS) is an accelerator-based neutron scattering research facility. The linear accelerator (linac) is the principal accelerating structure and divided into a room-temperature linac and a superconducting linac. The normal conducting linac system that consists of a Drift Tube Linac (DTL) and a Coupled Cavity Linac (CCL) is to be built by Los Alamos National Laboratory. The CCL structure is 55.36-meters long. It accelerates H- beam from 86.8 Mev to 185.6 Mev at operating frequency of 805 MHz. This side coupled cavity structure has 8 cells per segment, 12 segments and 11 bridge couplers per module, and 4 modules total. A 5-MW klystron powers each module. The number 3 and number 9 bridge coupler of each module are connected to the 5-MW RF power supply. The bridge coupler with length of 2.5 {beta}{gamma} is a three-cell structure and located between the segments and allows power flow through the module. The center cell of each bridge coupler is excited during normal operation. To obtain a uniform electromagnetic filed and meet the resonant frequency shift, the RF induced heat must be removed. Thus, the thermal deformation and frequency shift studies are performed via numerical simulations in order to have an appropriate cooling design and predict the frequency shift under operation. The center cell of the bridge coupler also contains a large 4-inch slug tuner and a tuning post that used to provide bulk frequency adjustment and field intensity adjustment, so that produce the proper total field distribution in the module assembly.

  3. Proton linac for hospital-based fast neutron therapy and radioisotope production

    SciTech Connect

    Lennox, A.J.; Hendrickson, F.R.; Swenson, D.A.; Winje, R.A.; Young, D.E.; Rush Univ., Chicago, IL; Science Applications International Corp., Princeton, NJ; Fermi National Accelerator Lab., Batavia, IL )

    1989-09-01

    Recent developments in linac technology have led to the design of a hospital-based proton linac for fast neutron therapy. The 180 microamp average current allows beam to be diverted for radioisotope production during treatments while maintaining an acceptable dose rate. During dedicated operation, dose rates greater than 280 neutron rads per minute are achievable at depth, DMAX = 1.6 cm with source to axis distance, SAD = 190 cm. Maximum machine energy is 70 MeV and several intermediate energies are available for optimizing production of isotopes for Positron Emission Tomography and other medical applications. The linac can be used to produce a horizontal or a gantry can be added to the downstream end of the linac for conventional patient positioning. The 70 MeV protons can also be used for proton therapy for ocular melanomas. 17 refs., 1 fig., 1 tab.

  4. A search for cosmogenic production of β-neutron emitting radionuclides in water

    NASA Astrophysics Data System (ADS)

    Dazeley, S.; Askins, M.; Bergevin, M.; Bernstein, A.; Bowden, N. S.; Shokair, T. M.; Jaffke, P.; Rountree, S. D.; Sweany, M.

    2016-06-01

    Here we present the first results of WATCHBOY, a water Cherenkov detector designed to measure the yield of β-neutron emitting radionuclides produced by cosmic ray muons in water. In addition to the β-neutron measurement, we also provide a first look at isolating single-β producing radionuclides following muon-induced hadronic showers as a check of the detection capabilities of WATCHBOY. The data taken over 207 live days indicates a 9Li production yield upper limit of 1.9 ×10-7μ-1g-1cm2 at ~400 m water equivalent (m.w.e.) overburden at the 90% confidence level. In this work the 9Li signal in WATCHBOY was used as a proxy for the combined search for 9Li and 8He production. This result will provide a constraint on estimates of antineutrino-like backgrounds in future water-based antineutrino detectors.

  5. Neutron production in deuterium gas-puff z-pinch with outer plasma shell at current of 3 MA

    NASA Astrophysics Data System (ADS)

    Cikhardt, J.; Klir, D.; Rezac, K.; Cikhardtova, B.; Kravarik, J.; Kubes, P.; Sila, O.; Shishlov, A. V.; Cherdizov, R. K.; Frusov, F. I.; Kokshenev, V. A.; Kurmaev, N. E.; Labetsky, A. Yu.; Ratakhin, N. A.; Dudkin, G. N.; Garapatsky, A. A.; Padalko, V. N.; Varlachev, V. A.; Turek, K.; Krasa, J.

    2015-11-01

    Z-pinch experiments at the current of about 3 MA were carried out on the GIT-12 generator. The outer plasma shell of deuterium gas-puff was generated by the system of 48 plasma guns. This configuration exhibits a high efficiency of the production of DD fusion neutrons with the yield of above 1012 neutrons produced in a single shot with the duration of about 20 ns. The maximum energy of the neutrons produced in this pulse exceeded 30 MeV. The neutron radiation was measured using scintillation TOF detectors, CR-39 nuclear track detectors, bubble detectors BD-PND and BDS-10000 and by several types of nuclear activation detectors. These diagnostic tools were used to measure the anisotropy of neutron fluence and neutron energy spectra. It allows us to estimate the total number of DD neutrons, the contribution of other nuclear reactions, the amount of scattered neutrons, and other parameters of neutron production. This work was supported by the MSMT grants LH13283, LD14089.

  6. In-phantom characterisation studies at the Birmingham Accelerator-Generated epIthermal Neutron Source (BAGINS) BNCT facility.

    PubMed

    Culbertson, Christopher N; Green, Stuart; Mason, Anna J; Picton, David; Baugh, Gareth; Hugtenburg, Richard P; Yin, Zaizhe; Scott, Malcolm C; Nelson, John M

    2004-11-01

    A broad experimental campaign to validate the final epithermal neutron beam design for the BNCT facility constructed at the University of Birmingham concluded in November 2003. The final moderator and facility designs are overviewed briefly, followed by a summary of the dosimetric methods and presentation of a small subset of the results from this campaign. The dual ionisation chamber technique was used together with foil activation to quantify the fast neutron, photon, and thermal neutron beam dose components in a large rectangular phantom exposed to the beam with a 12 cm diameter beam delimiter in place. After application of a normalisation factor, dose measurements agree with in-phantom MCNP4C predictions within 10% for the photon dose, within 10% for thermal neutron dose, and within 25% for the proton recoil dose along the main beam axis. PMID:15308136

  7. Simulation of neutron production in heavy metal targets using Geant4 software

    NASA Astrophysics Data System (ADS)

    Baldin, A. A.; Berlev, A. I.; Kudashkin, I. V.; Mogildea, G.; Mogildea, M.; Paraipan, M.; Tyutyunnikov, S. I.

    2016-03-01

    Inelastic hadronic interactions in heavy targets have been simulated using Geant4 and compared with experimental data for thin and thick lead and uranium targets. Special attention is paid to neutron and fission fragment production. Good agreement in the description of proton-beam interaction with thick targets is demonstrated, which is important for the simulation of experiments aimed at the development of subcritical reactors.

  8. Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production

    PubMed Central

    Morin, Jean-Benoît; Gimenez, Philippe; Edouard, Pascal; Arnal, Pierrick; Jiménez-Reyes, Pedro; Samozino, Pierre; Brughelli, Matt; Mendiguchia, Jurdan

    2015-01-01

    Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability. PMID:26733889

  9. Current Outlook for 99mTc Distribution Based on Electron Accelerator Production

    SciTech Connect

    Benjamin L. Nelson; W. David Bence; John R. Snyder

    2007-07-01

    In 1999 a practical example illustrating the economical and reliable production of 99mTc from an accelerator was developed. It included the realistic costs involved in establishing and operating the accelerator facility and the distribution of the 99mTc to regions in Florida. However, the technology was never commercialized. Recent political and economic developments prompted this second look at accelerator produced 99mTc. The practicality of this system in 2007 dollars was established to account for inflation and current demand. The same distribution model and production schedule from the Global ‘99 study were used. Numbers were found using current rates and costs where possible and indexed estimations when necessary. Though several of the costs increased significantly and the sale price remains at approximately 35¢/mCi, the unit cost of 99mTc throughput only increased from 12.8¢/mCi to 15.0¢/mCi or approximately 17.2% from 1999 to 2007 thus continuing to be economically viable. This study provides ground work for creating business development models at additional locations within the U.S.

  10. LANL Activities Supporting Electron Accelerator Production of 99Mo for NorthStar Medical Radioisotopes, LLC

    SciTech Connect

    Dale, Gregory E.; Kelsey, Charles T. IV; Woloshun, Keith A.; Holloway, Michael A.; Olivas, Eric R.; Dalmas, Dale A.; Romero, Frank P.; Hurtle, Kenneth P.

    2012-07-11

    Summary of LANL FY12 Activities are: (1) Preparation, performance, and data analysis for the FY12 accelerator tests at ANL - (a) LANL designed and installed a closed-loop helium target cooling system at ANL for the FY12 accelerator tests, (b) Thermal test was performed on March 27, (c) 24 h production test to follow the accelerator upgrade at ANL; (2) Local target shielding design and OTR/IR recommendations - (a) Target dose rate and activation products were calculated with MCNPX, (b) {sup 206}Pb({gamma},2n){sup 204m}Pb vs {sup 204g}Pb branching ratio unpublished, will measure using the LANL microtron, (c) OTR system nearing final configuration, (d) IR prototype system demonstrated during the recent thermal test at ANL; (3) Target housing lifetime estimation - Target housing material specifications and design to be finalized following the thermal test, lifetime not believed to be an issue; and (4) Target cooling system reliability - Long duration system characterizations will begin following the thermal test.

  11. 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.

  12. Constraints on binary neutron star merger product from short GRB observations

    NASA Astrophysics Data System (ADS)

    Gao, He; Zhang, Bing; Lü, Hou-Jun

    2016-02-01

    Binary neutron star (NS) mergers are strong gravitational-wave (GW) sources and the leading candidates to interpret short-duration gamma-ray bursts (SGRBs). Under the assumptions that SGRBs are produced by double neutron star mergers and that the x-ray plateau followed by a steep decay as observed in SGRB x-ray light curves marks the collapse of a supramassive neutron star to a black hole (BH), we use the statistical observational properties of Swift SGRBs and the mass distribution of Galactic double neutron star systems to place constraints on the neutron star equation of state (EoS) and the properties of the post-merger product. We show that current observations already impose the following interesting constraints. (1) A neutron star EoS with a maximum mass close to a parametrization of Mmax=2.37 M⊙(1 +1.58 ×10-10P-2.84) is favored. (2) The fractions for the several outcomes of NS-NS mergers are as follows: ˜40 % prompt BHs, ˜30 % supramassive NSs that collapse to BHs in a range of delay time scales, and ˜30 % stable NSs that never collapse. (3) The initial spin of the newly born supramassive NSs should be near the breakup limit (Pi˜1 ms ), which is consistent with the merger scenario. (4) The surface magnetic field of the merger products is typically ˜1015 G . (5) The ellipticity of the supramassive NSs is ɛ ˜(0.004 -0.007 ), so that strong GW radiation is released after the merger. (6) Even though the initial spin energy of the merger product is similar, the final energy output of the merger product that goes into the electromagnetic channel varies in a wide range from several 1049 to several 1052 erg , since a good fraction of the spin energy is either released in the form of GWs or falls into the black hole as the supramassive NS collapses.

  13. Production of Extremely Neutron-Rich Rare Isotopes at Texas A&M

    NASA Astrophysics Data System (ADS)

    Souliotis, G. A.; Veselsky, M.; Yennello, S. J.

    2002-03-01

    The production of extermely neutron-rich isotopes in heavy-ion collisions around and below the Fermi energy ( 30 MeV/ncleon) has been investigated using the MARS recoil separator at the Cyclotron Institute of Texas A&M University. At present, the reactions: 25 MeV/nucleon ^86Kr + ^64Ni and 21 MeV/nucleon ^124Sn+^124Sn have been investigated. The experimental results on cross sections obtained to date will be presented and compared with reaction simulations appropriate for this energy domain. The current calculations involve a deep inelastic transfer code for the primary interaction stage and a modern statistical evaporation code for the deexcitation stage. The results are also compared with higher energy projectile fragmentation data and available parametrizations. In general, we show that such reactions, near or below the Fermi energy, involving substantial nucleon exchange between the projectile and the target, can be a fruitful pathway to approach extremely neutron-rich nuclei towards the neutron drip-line. Apart from in-flight possibilities, the option of utilizing this type of reaction for rare isotope production in ISOL-based facilities will be mentioned. Finally, application of such reactions in current plans of both in-flight and ISOL-type rare beam production at Texas A&M will be discussed.

  14. Fusion-neutron production in the TFTR with deuterium neutral beam injection

    SciTech Connect

    Hendel, H.W.; England, A.C.; Jassby, D.L.; Mirin, A.A.; Nieschmidt, E.B.

    1986-06-01

    We report measurements of the fusion reaction rate in the Tokamak Fusion Test Reactor (TFTR) covering a wide range of plasma conditions and injected neutral beam powers up to 6.3 MW. The fusion-neutron production rate in beam-injected plasmas decreases slightly with increasing plasma density n/sub e/, even though the energy confinement parameter n/sub e/tau/sub E/ generally increases with density. The measurements indicate and Fokker-Planck simulations show that with increasing density the source of fusion neutrons evolves from mainly beam-beam and beam-target reactions at very low n/sub e/ to a combination of beam-target and thermonuclear reactions at high n/sub e/. At a given plasma current, the reduction in neutron source strength at higher n/sub e/ is due to both a decrease in electron temperature and in beam-beam reaction rate. The Fokker-Planck simulations also show that at low n/sub e/, plasma rotation can appreciably reduce the beam-target reaction rate for experiments with co-injection only. The variation of neutron source strength with plasma and beam parameters is as expected for beam-dominated regimes. However, the Fokker-Planck simulations systematically overestimate the measured source strength by a factor of 2 to 3; the source of this discrepancy has not yet been identified.

  15. Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC.

    PubMed

    Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

    2015-11-01

    A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed (28)Al, (24)Na, (54)Mn and (60)Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is (28)Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several (28)Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received. PMID:26265661

  16. Evaluation of equivalent dose from neutrons and activation products from a 15-MV X-ray LINAC

    PubMed Central

    Israngkul-Na-Ayuthaya, Isra; Suriyapee, Sivalee; Pengvanich, Phongpheath

    2015-01-01

    A high-energy photon beam that is more than 10 MV can produce neutron contamination. Neutrons are generated by the [γ,n] reactions with a high-Z target material. The equivalent neutron dose and gamma dose from activation products have been estimated in a LINAC equipped with a 15-MV photon beam. A Monte Carlo simulation code was employed for neutron and photon dosimetry due to mixed beam. The neutron dose was also experimentally measured using the Optically Stimulated Luminescence (OSL) under various conditions to compare with the simulation. The activation products were measured by gamma spectrometer system. The average neutron energy was calculated to be 0.25 MeV. The equivalent neutron dose at the isocenter obtained from OSL measurement and MC calculation was 5.39 and 3.44 mSv/Gy, respectively. A gamma dose rate of 4.14 µSv/h was observed as a result of activations by neutron inside the treatment machine. The gamma spectrum analysis showed 28Al, 24Na, 54Mn and 60Co. The results confirm that neutrons and gamma rays are generated, and gamma rays remain inside the treatment room after the termination of X-ray irradiation. The source of neutrons is the product of the [γ,n] reactions in the machine head, whereas gamma rays are produced from the [n,γ] reactions (i.e. neutron activation) with materials inside the treatment room. The most activated nuclide is 28Al, which has a half life of 2.245 min. In practice, it is recommended that staff should wait for a few minutes (several 28Al half-lives) before entering the treatment room after the treatment finishes to minimize the dose received. PMID:26265661

  17. Accelerator breeder nuclear fuel production: concept evaluation of a modified design for ORNL's proposed TME-ENFP

    SciTech Connect

    Johnson, J.O.; Gabriel, T.A.; Bartine, D.E.

    1985-01-01

    Recent advances in accelerator beam technology have made it possible to improve the target/blanket design of the Ternary Metal Fueled Electronuclear Fuel Producer (TMF-ENFP), an accelerator-breeder design concept proposed by Burnss et al. for subcritical breeding of the fissile isotope /sup 233/U. In the original TMF-ENFP the 300-mA, 1100-MeV proton beam was limited to a small diameter whose power density was so high that a solid metal target could not be used for producing the spallation neutrons needed to drive the breeding process. Instead the target was a central column of circulating liquid sodium, which was surrounded by an inner multiplying region of ternary fuel rods (/sup 239/Pu, /sup 232/Th, and /sup 238/U) and an outer blanket region of /sup 232/Th rods, with the entire system cooled by circulating sodium. In the modified design proposed here, the proton beam is sufficiently spread out to allow the ternary fuel to reside directly in the beam and to be preceded by a thin (nonstructural) V-Ti steel firThe spread beam mandated a change in the design configuration (from a cylindrical shape to an Erlenmeyer flask shape), which, in turn, required that the fuel rods (and blanket rods) be replaced by fuel pebbles. The fuel residence time in both systems was assumed to be 90 full power days. A series of parameter optimization calculations for the modified TMF-ENFP led to a semioptimized system in which the initial /sup 239/Pu inventory of the ternary fuel was 6% and the fuel pebble diameter was 0.5 cm. With this system the /sup 233/Pu production rate of 5.8 kg/day reported for the original TMF-ENFP was increased to 9.3 kg/day, and the thermal power production at beginning of cycle was increased from 3300 MW(t) to 5240 MW(t). 31 refs., 32 figs., 6 tabs.

  18. New sources and instrumentation for neutron science

    NASA Astrophysics Data System (ADS)

    Gil, Alina

    2011-04-01

    Neutron-scattering research has a lot to do with our everyday lives. Things like medicine, food, electronics, cars and airplanes have all been improved by neutron-scattering research. Neutron research also helps scientists improve materials used in a multitude of different products, such as high-temperature superconductors, powerful lightweight magnets, stronger, lighter plastic products etc. Neutron scattering is one of the most effective ways to obtain information on both, the structure and the dynamics of condensed matter. Most of the world's neutron sources were built decades ago, and although the uses and demand for neutrons have increased throughout the years, few new sources have been built. The new construction, accelerator-based neutron source, the spallation source will provide the most intense pulsed neutron beams in the world for scientific research and industrial development. In this paper it will be described what neutrons are and what unique properties make them useful for science, how spallation source is designed to produce neutron beams and the experimental instruments that will use those beams. Finally, it will be described how past neutron research has affected our everyday lives and what we might expect from the most exciting future applications.

  19. Measurements of photon and neutron leakage from medical linear accelerators and Monte Carlo simulation of tenth value layers of concrete used for intensity modulated radiation therapy treatment

    NASA Astrophysics Data System (ADS)

    Jaradat, Adnan Khalaf

    The x ray leakage from the housing of a therapy x ray source is regulated to be <0.1% of the useful beam exposure at a distance of 1 m from the source. The x ray leakage in the backward direction has been measured from linacs operating at 4, 6, 10, 15, and 18 MV using a 100 cm3 ionization chamber and track-etch detectors. The leakage was measured at nine different positions over the rear wall using a 3 x 3 matrix with a 1 m separation between adjacent positions. In general, the leakage was less than the canonical value, but the exact value depends on energy, gantry angle, and measurement position. Leakage at 10 MV for some positions exceeded 0.1%. Electrons with energy greater than about 9 MeV have the ability to produce neutrons. Neutron leakage has been measured around the head of electron accelerators at a distance 1 m from the target at 0°, 46°, 90°, 135°, and 180° azimuthal angles; for electron energies of 9, 12, 15, 16, 18, and 20 MeV and 10, 15, and 18 MV x ray photon beam, using a neutron bubble detector of type BD-PND and using Track-Etch detectors. The highest neutron dose equivalent per unit electron dose was at 0° for all electron energies. The neutron leakage from photon beams was the highest between all the machines. Intensity modulated radiation therapy (IMRT) delivery consists of a summation of small beamlets having different weights that make up each field. A linear accelerator room designed exclusively for IMRT use would require different, probably lower, tenth value layers (TVL) for determining the required wall thicknesses for the primary barriers. The first, second, and third TVL of 60Co gamma rays and photons from 4, 6, 10, 15, and 18 MV x ray beams by concrete have been determined and modeled using a Monte Carlo technique (MCNP version 4C2) for cone beams of half-opening angles of 0°, 3°, 6°, 9°, 12°, and 14°.

  20. Thermal annealing of stabilization products from recoil bromine-82 atoms in neutron-irradiated ammonium perbromate

    SciTech Connect

    Isupov, V.K.; Gavrilov, V.V.

    1987-11-01

    A study has been made on the thermal annealing of stabilization products from recoil bromine-82 atoms in neutron-irradiated ammonium perbromate. Paper and ion-exchange chromatography show that the oxidation of /sup 82/Br/sup -/ to /sup 82/BrO/sub 3//sup -/ in that case occurs only to a small extent, in contrast to alkali-metal perbromates. The effect is ascribed to metastable radiolysis products from the ammonium group. The pyrolysis of ammonium perbromate has also been examined.