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Sample records for slow neutron capture

  1. Analysis of slow neutron capture by /sup 9/Be, /sup 12/C, and /sup 13/C

    SciTech Connect

    Lynn, J.E.; Kahane, S.; Raman, S.

    1987-01-01

    We have analyzed the data on the primary radiative transitions following slow neutron capture by /sup 9/Be, /sup 12/C, and /sup 13/C. We have made estimates of direct capture from optical potential models with physically realistic parameters. These parameters were varied to allow for the effects of a local s-wave level on the initial state. We find that the model estimates are in reasonable agreement with the measured cross sections of the 6.810- and 0.854-MeV transitions in /sup 10/Be, the 1.262-MeV transition in /sup 13/C, and, possibly, the 8.174-MeV transition in /sup 14/C, indicating a major role played by a direct capture mechanism. In all these cases, the estimate of direct capture is greatly affected and reduced by large cancellation effects in the integrand of the radial dipole matrix element. The strengths of the 3.443-MeV transitions in /sup 10/Be and, to a lesser extent, the 4.945-MeV transition in /sup 13/C, cannot be explained by our optical model formulations of direct capture, but these strengths are consistent with extrapolations to these light nuclides of generally accepted formulations of compound nucleus capture.

  2. Database of prompt gamma rays from slow neutron capture forelemental analysis

    SciTech Connect

    Firestone, R.B.; Choi, H.D.; Lindstrom, R.M.; Molnar, G.L.; Mughabghab, S.F.; Paviotti-Corcuera, R.; Revay, Zs; Trkov, A.; Zhou,C.M.; Zerkin, V.

    2004-12-31

    The increasing importance of Prompt Gamma-ray ActivationAnalysis (PGAA) in a broad range of applications is evident, and has beenemphasized at many meetings related to this topic (e.g., TechnicalConsultants' Meeting, Use of neutron beams for low- andmedium-fluxresearch reactors: radiography and materialscharacterizations, IAEA Vienna, 4-7 May 1993, IAEA-TECDOC-837, 1993).Furthermore, an Advisory Group Meeting (AGM) for the Coordination of theNuclear Structure and Decay Data Evaluators Network has stated that thereis a need for a complete and consistent library of cold- and thermalneutron capture gammaray and cross-section data (AGM held at Budapest,14-18 October 1996, INDC(NDS)-363); this AGM also recommended theorganization of an IAEA CRP on the subject. The International NuclearData Committee (INDC) is the primary advisory body to the IAEA NuclearData Section on their nuclear data programmes. At a biennial meeting in1997, the INDC strongly recommended that the Nuclear Data Section supportnew measurements andupdate the database on Neutron-induced PromptGamma-ray Activation Analysis (21st INDC meeting, INDC/P(97)-20). As aconsequence of the various recommendations, a CRP on "Development of aDatabase for Prompt Gamma-ray Neutron Activation Analysis (PGAA)" wasinitiated in 1999. Prior to this project, several consultants had definedthe scope, objectives and tasks, as approved subsequently by the IAEA.Each CRP participant assumed responsibility for the execution of specifictasks. The results of their and other research work were discussed andapproved by the participants in research co-ordination meetings (seeSummary reports: INDC(NDS)-411, 2000; INDC(NDS)-424, 2001; andINDC(NDS)-443, 200). PGAA is a non-destructive radioanalytical method,capable of rapid or simultaneous "in-situ" multi-element analyses acrossthe entire Periodic Table, from hydrogen to uranium. However, inaccurateand incomplete data were a significant hindrance in the qualitative andquantitative analysis of complicated capture-gamma spectra by means ofPGAA. Therefore, the main goal of the CRP was to improve the quality andquantity of the required data in order to make possible the reliableapplication of PGAA in fields such as materials science, chemistry,geology, mining, archaeology, environment, food analysis and medicine.This aim wasachieved thanks to the dedicated work and effort of theparticipants. The CD-ROM included with this publication contains thedatabase, the retrieval system, the three CRM reports, and otherimportant electronic documents related to the CRP. The IAEA wishes tothanks all CRP participants who contributed to the success of the CRP andthe formulation of this publication. Special thanks are due to R.B.Firestone for his leading roll in the development of this CRP and hiscomprehensive compilation, analysis and provision of the adopteddatabase, and to V. Zerkin for the software developments associatedwiththe retrieval system. An essential component of this data compilation isthe extensive sets of new measurements of capture gamma-ray energies andintensities undertaken at Budapest by Zs. Revay under the direction ofG.L. Molnar. The extensive participation and assistance of H.D. Choi isalso greatly appreciated. Other participants inthis CRP were: R.M.Lindstrom, S.M. Mughabghab, A.V.R. Reddy, V.H. Tan and C.M. Zhou. Thanksare also due to S.C. Frankle and M.A. Lone for their active participationas consultants at some of the meetings. Finally, the participants wish tothank R. Paviotti-Corcuera (Nuclear Data Section, Division of Physicaland Chemical Sciences), who was the IAEA responsible officer for the CRP,this publication and the resulting database. The participants aregrateful to D.L. Muir and A.L. Nichols, successive Heads of the NuclearData Section, for their active and enthusiastic encouragement infurthering the work of the CRP.

  3. Neutron capture therapies

    DOEpatents

    Yanch, Jacquelyn C. (Cambridge, MA); Shefer, Ruth E. (Newton, MA); Klinkowstein, Robert E. (Winchester, MA)

    1999-01-01

    In one embodiment there is provided an application of the .sup.10 B(n,.alpha.).sup.7 Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

  4. Neutron capture therapies

    SciTech Connect

    Yanch, J.C.; Shefer, R.E.; Klinkowstein, R.E.

    1999-11-02

    In one embodiment there is provided an application of the {sup 10}B(n,{alpha}){sup 7}Li nuclear reaction or other neutron capture reactions for the treatment of rheumatoid arthritis. This application, called Boron Neutron Capture Synovectomy (BNCS), requires substantially altered demands on neutron beam design than for instance treatment of deep seated tumors. Considerations for neutron beam design for the treatment of arthritic joints via BNCS are provided for, and comparisons with the design requirements for Boron Neutron Capture Therapy (BNCT) of tumors are made. In addition, exemplary moderator/reflector assemblies are provided which produce intense, high-quality neutron beams based on (p,n) accelerator-based reactions. In another embodiment there is provided the use of deuteron-based charged particle reactions to be used as sources for epithermal or thermal neutron beams for neutron capture therapies. Many d,n reactions (e.g. using deuterium, tritium or beryllium targets) are very prolific at relatively low deuteron energies.

  5. Iodine neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Ahmed, Kazi Fariduddin

    A new technique, Iodine Neutron Capture Therapy (INCT) is proposed to treat hyperthyroidism in people. Present thyroid therapies, surgical removal and 131I treatment, result in hypothyroidism and, for 131I, involve protracted treatment times and excessive whole-body radiation doses. The new technique involves using a low energy neutron beam to convert a fraction of the natural iodine stored in the thyroid to radioactive 128I, which has a 24-minute half-life and decays by emitting 2.12-MeV beta particles. The beta particles are absorbed in and damage some thyroid tissue cells and consequently reduce the production and release of thyroid hormones to the blood stream. Treatment times and whole-body radiation doses are thus reduced substantially. This dissertation addresses the first of the several steps needed to obtain medical profession acceptance and regulatory approval to implement this therapy. As with other such programs, initial feasibility is established by performing experiments on suitable small mammals. Laboratory rats were used and their thyroids were exposed to the beta particles coming from small encapsulated amounts of 128I. Masses of 89.0 mg reagent-grade elemental iodine crystals have been activated in the ISU AGN-201 reactor to provide 0.033 mBq of 128I. This activity delivers 0.2 Gy to the thyroid gland of 300-g male rats having fresh thyroid tissue masses of ˜20 mg. Larger iodine masses are used to provide greater doses. The activated iodine is encapsulated to form a thin (0.16 cm 2/mg) patch that is then applied directly to the surgically exposed thyroid of an anesthetized rat. Direct neutron irradiation of a rat's thyroid was not possible due to its small size. Direct in-vivo exposure of the thyroid of the rat to the emitted radiation from 128I is allowed to continue for 2.5 hours (6 half-lives). Pre- and post-exposure blood samples are taken to quantify thyroid hormone levels. The serum T4 concentration is measured by radioimmunoassay at different times after exposure as an indicator of thyroid function. Cell damage is assessed by postmortem histopathologic examination. The intent of this endeavor is to relate radiation dose, T4 concentration in the blood stream and cellular damage. This information will help better understand the dose response relationship of thyroid cells exposed to ionizing radiation.

  6. Neutron capture reactions at DANCE

    SciTech Connect

    Bredeweg, T. A.

    2008-05-12

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 4{pi} BaF{sub 2} array consisting of 160 active detector elements. The primary purpose of the array is to perform neutron capture cross section measurements on small (> or approx.100 {mu}g) and/or radioactive (< or approx. 100 mCi) species. The measurements made possible with this array will be useful in answering outstanding questions in the areas of national security, threat reduction, nuclear astrophysics, advanced reactor design and accelerator transmutation of waste. Since the commissioning of DANCE we have performed neutron capture cross section measurements on a wide array of medium to heavy mass nuclides. Measurements to date include neutron capture cross sections on {sup 241,243}Am, neutron capture and neutron-induced fission cross sections and capture-to-fission ratio ({alpha} = {sigma}{sub {gamma}}/{sigma}{sub f}) for {sup 235}U using a new fission-tagging detector as well as neutron capture cross sections for several astrophysics branch-point nuclei. Results from several of these measurements will be presented along with a discussion of additional physics information that can be extracted from the DANCE data.

  7. Neutron capture reactions at DANCE

    NASA Astrophysics Data System (ADS)

    Bredeweg, T. A.

    2008-05-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 4π BaF2 array consisting of 160 active detector elements. The primary purpose of the array is to perform neutron capture cross section measurements on small (>~100 μg) and/or radioactive (<~100 mCi) species. The measurements made possible with this array will be useful in answering outstanding questions in the areas of national security, threat reduction, nuclear astrophysics, advanced reactor design and accelerator transmutation of waste. Since the commissioning of DANCE we have performed neutron capture cross section measurements on a wide array of medium to heavy mass nuclides. Measurements to date include neutron capture cross sections on 241,243Am, neutron capture and neutron-induced fission cross sections and capture-to-fission ratio (α = σγ/σf) for 235U using a new fission-tagging detector as well as neutron capture cross sections for several astrophysics branch-point nuclei. Results from several of these measurements will be presented along with a discussion of additional physics information that can be extracted from the DANCE data.

  8. Neutron source for Neutron Capture Synovectomy

    NASA Astrophysics Data System (ADS)

    Vega-Carrillo, Hctor Ren; Manzanares-Acua, Eduardo

    2002-08-01

    Monte Carlo calculations were performed to obtain a thermal neutron field from a 239PuBe neutron source inside a cylindrical heterogeneous moderators for Neutron Capture Synovectomy. Studied moderators were light water and heavy water, graphite and heavy water, lucite and polyethylene and heavy water. The neutron spectrum of polyethylene and heavy water moderator was used to determine neutron spectra inside a knee model. In this model the elemental composition of synovium and synovial liquid was assumed like blood. Kerma factors for synovium and synovial liquid were calculated to compare with water Kerma factors, in this calculations the synovium was loaded with two different concentrations of Boron.

  9. Neutron Capture Reactions on Fe and Ni Isotopes for the Astrophysical s-process

    NASA Astrophysics Data System (ADS)

    Lederer, C.; Giubrone, G.; Massimi, C.; Žugec, P.; Barbagallo, M.; Colonna, N.; Domingo-Pardo, C.; Guerrero, C.; Gunsing, F.; Käppeler, F.; Tain, J. L.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Duran, I.; Dressler, R.; Dzysiuk, N.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A. R.; Gómez-Hornillos, M. B.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Gurusamy, P.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Karadimos, D.; Kivel, N.; Koehler, P.; Kokkoris, M.; Korschinek, G.; Krtička, M.; Kroll, J.; Langer, C.; Leeb, H.; Leong, L. S.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Mastinu, P. F.; Mastromarco, M.; Meaze, M.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondelaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Pignatari, M.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego, A.; Roman, F.; Rubbia, C.; Sarmento, R.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T. J.

    2014-06-01

    Neutron capture cross sections in the keV neutron energy region are the key nuclear physics input to study the astrophysical slow neutron capture process. In the past years, a series of neutron capture cross section measurements has been performed at the neutron time-of-flight facility n_TOF at CERN focussing on the Fe/Ni mass region. Recent results and future developments in the neutron time-of-flight technique are discussed.

  10. Neutron Capture Reactions on Fe and Ni Isotopes for the Astrophysical s-process

    SciTech Connect

    Lederer, C.; Giubrone, G.; Massimi, C.; Žugec, P.; Barbagallo, M.; Colonna, N.; Domingo-Pardo, C.; Guerrero, C.; Gunsing, F.; Käppeler, F.; Tain, J.L.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bečvář, F.; and others

    2014-06-15

    Neutron capture cross sections in the keV neutron energy region are the key nuclear physics input to study the astrophysical slow neutron capture process. In the past years, a series of neutron capture cross section measurements has been performed at the neutron time-of-flight facility n{sub T}OF at CERN focussing on the Fe/Ni mass region. Recent results and future developments in the neutron time-of-flight technique are discussed.

  11. [Epithermal neutron capture therapy

    SciTech Connect

    Not Available

    1993-01-01

    Development of a 4 mA, 2.5 MeV Tandem Cascade Accelerator (TCA) for the production of neutrons via the [sup 7]Li(p,n)[sup 7]Be nuclear reaction is currently nearing completion at SRL. The TCA is a tandem electrostatic accelerator which uses a high current negative ion source in conjunction with a high current solid state cascade multiplier power supply to provide a compact, low cost, proton accelerator capable of supplying multi-milliampere currents at several million electron volts. The inherent simplicity and flexibility of this accelerator provide several features which are desirable for laboratory and clinical applications requiring the generation of high neutron fluxes. The beam aperture of the accelerating tube is large so that critical focusing and alignment of the beam is not required. Both the ion beam source and target are at ground potential during operation. This configuration allows different moderator geometries to be incorporated easily into the target design. A high degree of compactness is achieved by a patented SRL design which allows the power supply to be mounted directly onto the accelerating column thereby eliminating the need for an external power supply chassis. The TCA is unique in its capability to accelerate multi-milliampere ion beams to 2.5 MeV. A direct result of the patented high current solid-state power supply developed by SRL and the use of a high current, high brightness multicusp negative ion source. The TCA requires no RF or magnetic fields which greatly reduces the system weight, power dissipation and heat load on auxiliary systems when compared with radiofrequency quadrupole (RFQ) or cyclotron-type accelerators. Delivery of current is continuous, rather than pulsed as in an RFQ, which reduces the peak thermal and mechanical stresses on the target and simplifies target design. The accelerator weighs less than 2,000 lbs., has an overall length of approximately 2.6 m, and requires approximately 25 kW of electrical power.

  12. 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,??)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 1.4108 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 proposal is made to construct an electrostatic, 2.5 MeV, 50 mA proton accelerator suitable for hospital use. A combination of a Tandem and an Electrostatic Quadrupole is considered to be the best option.

  13. Neutron capture cross section of 136 Xe

    NASA Astrophysics Data System (ADS)

    Daugherty, Sean; Albert, Joshua; Johnson, Tessa; O'Conner, Thomasina; Kaufman, Lisa

    2015-04-01

    136 Xe is an important 0 ??? candidate, studied in experiments such as EXO-200 and, in the future, nEXO. These experiments require a precise study of neutron capture for their background models. The neutron capture cross section of 136 Xe has been measured at the Detector for Advanced Capture Experiments (DANCE) at the Los Alamos Neutron Science Center. A neutron beam ranging from thermal energy to 100 keV was incident on a gas cell filled with isotopically pure 136 Xe . We will discuss the measurement of partial neutron capture cross sections at thermal and first neutron resonance energies along with corresponding capture gamma cascades.

  14. Neutron dosimetry in boron neutron capture therapy

    SciTech Connect

    Fairchild, R.G.; Miola, U.J.; Ettinger, K.V.

    1981-01-01

    The recent development of various borated compounds and the utilization of one of these (Na/sub 2/B/sub 12/H/sub 11/SH) to treat brain tumors in clinical studies in Japan has renewed interest in neutron capture therapy. In these procedures thermal neutrons interact with /sup 10/B in boron containing cells through the /sup 10/B(n,..cap alpha..)/sup 7/Li reaction producing charged particles with a maximum range of approx. 10..mu..m in tissue. Borated analogs of chlorpromazine, porphyrin, thiouracil and deoxyuridine promise improved tumor uptake and blood clearance. The therapy beam from the Medical Research Reactor in Brookhaven contains neutrons from a modified and filtered fission spectrum and dosimetric consequences of the use of the above mentioned compounds in conjunction with thermal and epithermal fluxes are discussed in the paper. One of the important problems of radiation dosimetry in capture therapy is determination of the flux profile and, hence, the dose profile in the brain. This has been achieved by constructing a brain phantom made of TE plastic. The lyoluminescence technique provides a convenient way of monitoring the neutron flux distributions; the detectors for this purpose utilize /sup 6/Li and /sup 10/B compounds. Such compounds have been synthesized specially for the purpose of dosimetry of thermal and epithermal beams. In addition, standard lyoluminescent phosphors, like glutamine, could be used to determine the collisional component of the dose as well as the contribution of the /sup 14/N(n,p)/sup 14/C reaction. Measurements of thermal flux were compared with calculations and with measurements done with activation foils.

  15. Workshop on neutron capture therapy

    SciTech Connect

    Fairchild, R.G.; Bond, V.P.

    1986-01-01

    Potentially optimal conditions for Neutron Capture Therapy (NCT) may soon be in hand due to the anticipated development of band-pass filtered beams relatively free of fast neutron contaminations, and of broadly applicable biomolecules for boron transport such as porphyrins and monoclonal antibodies. Consequently, a number of groups in the US are now devoting their efforts to exploring NCT for clinical application. The purpose of this Workshop was to bring these groups together to exchange views on significant problems of mutual interest, and to assure a unified and effective approach to the solutions. Several areas of preclinical investigation were deemed to be necessary before it would be possible to initiate clinical studies. As neither the monomer nor the dimer of sulfhydryl boron hydride is unequivocally preferable at this time, studies on both compounds should be continued until one is proven superior.

  16. Experimental studies of gravity with slow neutrons

    NASA Astrophysics Data System (ADS)

    Kitaguchi, Masaaki; Ichikawa, Go; Hirota, Katsuya; Shimizu, Hirohiko; Sumi, Naoyuki; Matsumoto, Satoru; Yoshioka, Tamaki; Shima, Tatsushi; Mishima, Kenji; Ino, Takashi; Seki, Yoshichika

    2014-09-01

    Neutron is a chargeless massive particle with the lifetime in the macroscopic range, which is suitable for precision measurement of the small influence of new physics including gravity. We have started the experimental studies of the gravity with slow neutrons in order to search non-Newtonian effect at the short range which is lead by the existence of extra-dimension of the space. Combination of the pulsed neutrons provided by J-PARC and the advanced optical devices enables us to perform new types of high precision measurements. Neutron scattering with noble gas target enables us to measure the interaction at the range of the order of 1 nm. The apparatus was installed into beamline NOP and commissioning has been started. Neutron interferometer has the advantage to measure the gravitational potential precisely. We are developing the large-scale interferometer using long-wavelength neutrons, which is realized by using multilayer mirrors. Ultra-cold neutrons in a small cavity can be bound to the discrete energy eigenstates by Earth's gravitational field. We are discussing the direct measurement of the spatial localization of the neutrons with high resolution detectors, for example, CCD and nuclear emulation.

  17. Neutron Capture Reactions for Stockpile Stewardship and Basic Science

    SciTech Connect

    Parker, W; Agvaanluvsan, U; Becker, J; Wilk, P; Wu, C; Bredeweg, T; Couture, A; Haight, R; Jandel, M; O'Donnell, J; Reifarth, R; Rundberg, R; Ullmann, J; Vieira, D; Wouters, J; Sheets, S; Mitchell, G; Becvar, F; Krticka, M

    2007-08-04

    The capture process is a nuclear reaction in which a target atom captures an incident projectile, e.g. a neutron. The excited-state compound nucleus de-excites by emitting photons. This process creates an atom that has one more neutron than the target atom, so it is a different isotope of the same element. With low energy (slow) neutron projectiles, capture is the dominant reaction, other than elastic scattering. However, with very heavy nuclei, fission competes with capture as a method of de-excitation of the compound nucleus. With higher energy (faster) incident neutrons, additional reactions are also possible, such as emission of protons or emission of multiple neutrons. The probability of a particular reaction occurring (such as capture) is referred to as the cross section for that reaction. Cross sections are very dependent on the incoming neutron's energy. Capture reactions can be studied either using monoenergetic neutron sources or 'white' neutron sources. A 'white' neutron source has a wide range of neutron energies in one neutron beam. The advantage to the white neutron source is that it allows the study of cross sections as they depend on neutron energies. The Los Alamos Neutron Science Center, located at Los Alamos National Laboratory, provides an intense white neutron source. Neutrons there are created by a high-energy proton beam from a linear accelerator striking a heavy metal (tungsten) target. The neutrons range in energy from subthermal up to very fast - over 100 MeV in energy. Low-energy neutron reaction cross sections fluctuate dramatically from one target to another, and they are very difficult to predict by theoretical modeling. The cross sections for particular capture reactions are important for defense sciences, advanced reactor concepts, transmutation of radioactive wastes and nuclear astrophysics. We now have a strong collaboration between Lawrence Livermore National Laboratory, Los Alamos National Laboratory, North Carolina State University and Charles University in Prague. In this paper, we report neutron capture studies that are of particular interest to Lawrence Livermore National Laboratory. In addition to determining neutron capture cross sections, we are also interested in the nuclear properties of the excited state compound nuclei created in the capture reactions. One model that describes the behavior of the nucleus is the statistical model. Our statistical studies included measuring the photon strength function, resonance parameters, level density and gamma-ray ({gamma}-ray) cascade multiplicity. The DANCE array allows the separation of cascades by the number of transitions (multiplicity) in the cascade, and this makes it possible to study detailed properties of the statistical cascade such as the relationship between multiplicity and energy distributions. The work reported here includes reaction on molybdenum targets, europium targets, gadolinium targets and the first americium-242m target. Our goal is to improve the accuracy and provide new measurements for stable and radioactive targets. We are especially interested in energy-dependent neutron capture cross sections. In all of our experiments, the photons emitted in the capture reactions are gamma rays, and they are detected by the barium fluoride crystal array named the Detector for Advanced Neutron Capture Experiments (DANCE) shown in Fig. 1. The detector array is made of 160 crystals arranged in a sphere around the target. There are four different crystal shapes, each of which covers an equal solid angle. This array was specifically designed to measure neutron capture cross sections with targets that were milligram sized or smaller, including radioactive targets. The barium fluoride crystals are scintillation (light generating) detectors with very fast response time, and are therefore suitable for high count rate experiments. Actual neutron capture events must be reliably distinguished from background {gamma}-rays, which are always present in neutron induced reactions. To reduce the background of scattered neutrons, a lithium hyd

  18. Neutron beam design, development, and performance for neutron capture therapy

    SciTech Connect

    Harling, O.K.; Bernard, J.A. ); Zamenhof, R.G. )

    1990-01-01

    The report presents topics presented at a workshop on neutron beams and neutron capture therapy. Topics include: neutron beam design; reactor-based neutron beams; accelerator-based neutron beams; and dosimetry and treatment planning. Individual projects are processed separately for the databases. (CBS)

  19. Benchmarking a surrogate reaction for neutron capture

    SciTech Connect

    Hatarik, R.; Cizewski, J. A.; Hatarik, A. M.; O'Malley, P. D.; Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Escher, J. E.; Lesher, S. R.; Gibelin, J.; Phair, L.; Rodriguez-Vieitez, E.; Goldblum, B. L.; Swan, T.; Wiedeking, M.

    2010-01-15

    {sup 171,173}Yb(d,p{gamma}) reactions are measured, with the goal of extracting the neutron capture cross-section ratio as a function of the neutron energy using the external surrogate ratio method. The cross-section ratios obtained are compared to the known neutron capture cross sections. Although the Weisskopf-Ewing limit is demonstrated not to apply for these low neutron energies, a prescription for deducing surrogate cross sections is presented. The surrogate cross-section ratios deduced from the {sup 171,173}Yb(d,p{gamma}) measurements agree with the neutron capture results within 15%.

  20. Neutron capture therapy for melanoma

    SciTech Connect

    Coderre, J.A.; Glass, J.D.; Micca, P.; Fairchild, R.G.

    1988-01-01

    The development of boron-containing compounds which localize selectively in tumor may require a tumor-by-tumor type of approach that exploits any metabolic pathways unique to the particular type of tumor. Melanin-producing melanomas actively transport and metabolize aromatic amino acids for use as precursors in the synthesis of the pigment melanin. It has been shown that the boron-containing amino acid analog p-borono-phenylalanine (BPA) is selectively accumulated in melanoma tissue, producing boron concentrations in tumor that are within the range estimated to be necessary for successful boron neutron capture therapy (BNCT). We report here the results of therapy experiments carried out at the Brookhaven Medical Research Reactor (BMRR). 21 refs., 5 figs., 3 tabs.

  1. Slow neutron leakage spectra from spallation neutron sources

    SciTech Connect

    Das, S.G.; Carpenter, J.M.; Prael, R.E.

    1980-02-01

    An efficient technique is described for Monte Carlo simulation of neutron beam spectra from target-moderator-reflector assemblies typical of pulsed spallation neutron sources. The technique involves the scoring of the transport-theoretical probability that a neutron will emerge from the moderator surface in the direction of interest, at each collision. An angle-biasing probability is also introduced which further enhances efficiency in simple problems. These modifications were introduced into the VIM low energy neutron transport code, representing the spatial and energy distributions of the source neutrons approximately as those of evaporation neutrons generated through the spallation process by protons of various energies. The intensity of slow neutrons leaking from various reflected moderators was studied for various neutron source arrangements. These include computations relating to early measurements on a mockup-assembly, a brief survey of moderator materials and sizes, and a survey of the effects of varying source and moderator configurations with a practical, liquid metal cooled uranium source Wing and slab, i.e., tangential and radial moderator arrangements, and Be vs CH/sub 2/ reflectors are compared. Results are also presented for several complicated geometries which more closely represent realistic arrangements for a practical source, and for a subcritical fission multiplier such as might be driven by an electron linac. An adaptation of the code was developed to enable time dependent calculations, and investigated the effects of the reflector, decoupling and void liner materials on the pulse shape.

  2. Neutron-capture resonances for 82Se

    NASA Astrophysics Data System (ADS)

    Browne, J. C.; Berman, B. L.

    1982-09-01

    Strong neturon-capture resonances for 82Se have been found at 3.63, 7.1, and 9.51 keV and weaker ones have been found at 0.58, 1.15, and possibly 13.54 and 16.5 keV. None was found at lower neutron energies; this absence of strong epithermal capture resonances invalidates the hypothesis that the depth dependence of the abundance ratio of 78Kr to 83Kr found in meteoritic studies owes its origin to anomalous 83Kr production by neutron capture on 82Se. Precise energies have been assigned to neutron-capture resonances up to 40 keV for all the other selenium isotopes as well. NUCLEAR REACTIONS 82Se, natSe(n, γ) neutron time of flight; resonance energies; abundance ratio of 78Kr to 83Kr.

  3. Gadolinium as a neutron capture therapy agent.

    PubMed

    Shih, J L; Brugger, R M

    1992-01-01

    The clinical results of treating brain tumors with boron neutron capture therapy are very encouraging. Researchers around the world are once again making efforts to develop this therapeutic modality. Gadolinium-157 is one of the nuclides that holds interesting properties of being a neutron capture therapy agent. It is estimated that tumor concentrations of up to 300 micrograms 157 Gd/g tumor can be achieved in brain tumors with some MRI contrast agents such as Gd-DTPA and Gd-DOTA, and up to 800 micrograms 157 Gd/g tumor can be established in bone tumors with Gd-EDTMP. Monte Carlo calculations indicate that with 250 ppm of 157Gd in tumor, neutron capture therapy can deliver 2000 cGy to a tumor of 2-cm diameter or larger with 5 x 10(12) n/cm2 of thermal neutron fluence at the tumor. Dose measurements with films and TLDs in phantoms verified these calculations. More extended Monte Carlo calculations demonstrate that neutron capture therapy with Gd possesses comparable dose distribution to B neutron capture therapy. With 5 x 10(12) n/cm2 thermal neutrons at the tumor, Auger electrons from the Gd produced an optical density enhancement on films that is similar to the effect caused by about 300 cGy of Gd prompt gamma dose and may further enhance the therapeutic effects. PMID:1508113

  4. Neutron capture cross section of ^243Am

    NASA Astrophysics Data System (ADS)

    Jandel, M.

    2009-10-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory (LANL) was used for neutron capture cross section measurement on ^243Am. The high granularity of DANCE (160 BaF2 detectors in a 4π geometry) enables the efficient detection of prompt gamma-rays following neutron capture. DANCE is located on the 20.26 m neutron flight path 14 (FP14) at the Manuel Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center (LANSCE). The methods and techniques established in [1] were used for the determination of the ^243Am neutron capture cross section. The cross sections were obtained in the range of neutron energies from 0.02 eV to 400 keV. The resonance region was analyzed using SAMMY7 and resonance parameters were extracted. The results will be compared to existing evaluations and calculations. Work was performed under the auspices of the U.S. Department of Energy at Los Alamos National Laboratory by the Los Alamos National Security, LLC under Contract No. DE-AC52-06NA25396 and at Lawrence Livermore National Laboratory by the Lawrence Livermore National Security, LLC under Contract No. DE-AC52-07NA27344. [4pt] [1] M. Jandel et al., Phys. Rev. C78, 034609 (2008)

  5. Neutron capture therapy research in Australia.

    PubMed

    Allen, B J

    1989-01-01

    Neutron capture therapy research in Australia has continued to grow since the first Australia-Japan workshop in April, 1986. The support base has broadened and the wide range of contributing laboratories includes universities, research institutes, and hospitals. Considerable progress has been made in boron chemistry--an accurate boron assay technique has been developed, boron analogues of chlorpromazine and thiouracil have been synthesised or nearly so, and decaborane conjugation with monoclonal antibodies has been achieved to the required loadings. In vitro cell survival experiments are proceeding in the Moata reactor using human melanoma and mouse cell lines incubated with enriched boronophenylalanine and boron tetraphenyl porphyrins. Electron microscopy examination of radiation damaged morphology shows considerable differences between cell lines. Progress with the nude mouse human melanoma model has been slow because of the lack of a reliable in vivo melanotic melanoma line, and the B16 mouse line is found to be more efficacious. Tailored beam calculations for the 10 MW HIFAR reactor indicate the difficulty of obtaining a suitable therapeutic beam because of the generated gamma dose in the beam filters. A new approach to NCT utilises the enormous cross section of 157Gd and the induced-Auger effect which has been shown to cause double strand breaks in circular DNA. PMID:2678079

  6. Neutron capture therapy research in Australia

    SciTech Connect

    Allen, B.J.

    1989-07-01

    Neutron capture therapy research in Australia has continued to grow since the first Australia-Japan workshop in April, 1986. The support base has broadened and the wide range of contributing laboratories includes universities, research institutes, and hospitals. Considerable progress has been made in boron chemistry--an accurate boron assay technique has been developed, boron analogues of chlorpromazine and thiouracil have been synthesised or nearly so, and decaborane conjugation with monoclonal antibodies has been achieved to the required loadings. In vitro cell survival experiments are proceeding in the Moata reactor using human melanoma and mouse cell lines incubated with enriched boronophenylalanine and boron tetraphenyl porphyrins. Electron microscopy examination of radiation damaged morphology shows considerable differences between cell lines. Progress with the nude mouse human melanoma model has been slow because of the lack of a reliable in vivo melanotic melanoma line, and the B16 mouse line is found to be more efficacious. Tailored beam calculations for the 10 MW HIFAR reactor indicate the difficulty of obtaining a suitable therapeutic beam because of the generated gamma dose in the beam filters. A new approach to NCT utilises the enormous cross section of 157Gd and the induced-Auger effect which has been shown to cause double strand breaks in circular DNA. 34 references.

  7. Neutron-Resonance Capture Analysis of Materials

    SciTech Connect

    Postma, H.; Bode, P.; Blaauw, M.; Corvi, F.

    1999-11-14

    Epithermal neutron activation analysis is a well-established approach to improve the sensitivity for certain elements by suppressing the activation of interfering elements. If epithermal neutrons of a given energy could be selected, the signal-to-noise ratio might be further improved by taking advantage of resonance capture. This reaction occurs mainly by intermediate and heavy nuclei. Moreover, most of these reactions take place with epithermal or fast neutrons. Intense epithermal neutrons are available as ''white'' beams at accelerator-driven neutron sources. Neutron resonance capture offers interesting analytical opportunities. Low-Z elements have little capture of epithermal neutrons and are thus virtually absent in the time-of-flight spectrum. Relatively large objects can be placed in the neutron beam and analyzed nondestructively. The induced radioactivity is relatively low. If an element has several stable isotopes, each of these isotopes can be recognized by its specific resonances. This would allow for multitracer studies with several isotopically labeled compounds. Different from mass spectrometry, the sample remains intact and can be used for further studies after analysis. Applications may be in the field of archaeology, metallurgy, and certification of reference materials.

  8. Gadolinium as a Neutron Capture Therapy Agent

    NASA Astrophysics Data System (ADS)

    Shih, Jing-Luen Allen

    The clinical results of treating brain tumors with boron neutron capture therapy are very encouraging and researchers around the world are once again making efforts to develop this therapeutic modality. Boron-10 is the agent receiving the most attention for neutron capture therapy but ^{157}Gd is a nuclide that also holds interesting properties of being a neutron capture therapy agent. The objective of this study is to evaluate ^{157}Gd as a neutron capture therapy agent. In this study it is determined that tumor concentrations of about 300 mug ^{157}Gd/g tumor can be achieved in brain tumors with some FDA approved MRI contrast agents such as Gd-DTPA and Gd-DOTA, and up to 628 mug ^{157 }Gd/g tumor can be established in bone tumors with Gd-EDTMP. Monte Carlo calculations show that with only 250 ppm of ^{157}Gd in tumor, neutron capture therapy can deliver 2,000 cGy to a tumor of 2 cm diameter or larger with 5 times 10^{12} n/cm ^2 fluence at the tumor. Dose measurements which were made with films and TLD's in phantoms verified these calculations. More extended Monte Carlo calculations demonstrate that neutron capture therapy with Gd possesses comparable dose distribution to B neutron capture therapy. With 5 times 10^{12 } n/cm^2 thermal neutrons at the tumor, Auger electrons from the Gd produced an optical density enhancement on the films that is similar to the effect caused by about 300 cGy of Gd prompt gamma dose which will further enhance the therapeutic effects. A technique that combines brachytherapy with Gd neutron capture therapy has been evaluated. Monte Carlo calculations show that 5,000 cGy of prompt gamma dose can be delivered to a treatment volume of 40 cm^3 with a 3-plane implant of a total of 9 Gd needles. The tumor to normal tissue advantage of this method is as good as ^{60} Co brachytherapy. Measurements of prompt gamma dose with films and TLD-700's in a lucite phantom verify the Monte Carlo evaluation. A technique which displays the Gd distribution and its relative concentration in samples has been developed. Concentrations of ^{157}Gd in samples range from 20 ppm to 500 ppm can be determined with this technique. The intrinsic spatial resolution of the imaging system in 70 mum.

  9. Approach to magnetic neutron capture therapy

    SciTech Connect

    Kuznetsov, Anatoly A. . E-mail: spod@sky.chph.ras.ru; Podoynitsyn, Sergey N.; Filippov, Victor I.; Komissarova, Lubov Kh.; Kuznetsov, Oleg A.

    2005-11-01

    Purpose: The method of magnetic neutron capture therapy can be described as a combination of two methods: magnetic localization of drugs using magnetically targeted carriers and neutron capture therapy itself. Methods and Materials: In this work, we produced and tested two types of particles for such therapy. Composite ultradispersed ferro-carbon (Fe-C) and iron-boron (Fe-B) particles were formed from vapors of respective materials. Results: Two-component ultradispersed particles, containing Fe and C, were tested as magnetic adsorbent of L-boronophenylalanine and borax and were shown that borax sorption could be effective for creation of high concentration of boron atoms in the area of tumor. Kinetics of boron release into the physiologic solution demonstrate that ultradispersed Fe-B (10%) could be applied for an effective magnetic neutron capture therapy. Conclusion: Both types of the particles have high magnetization and magnetic homogeneity, allow to form stable magnetic suspensions, and have low toxicity.

  10. DYNAMICAL CAPTURE BINARY NEUTRON STAR MERGERS

    SciTech Connect

    East, William E.; Pretorius, Frans

    2012-11-20

    We study dynamical capture binary neutron star mergers as may arise in dense stellar regions such as globular clusters. Using general-relativistic hydrodynamics, we find that these mergers can result in the prompt collapse to a black hole or in the formation of a hypermassive neutron star, depending not only on the neutron star equation of state but also on impact parameter. We also find that these mergers can produce accretion disks of up to a tenth of a solar mass and unbound ejected material of up to a few percent of a solar mass. We comment on the gravitational radiation and electromagnetic transients that these sources may produce.

  11. Radioactivity induced by neutrons: Enrico Fermi and a thermodynamic approach to radiative capture

    NASA Astrophysics Data System (ADS)

    De Gregorio, Alberto

    2006-07-01

    When Fermi learned that slow neutrons are much more effective than fast ones in inducing radioactivity, he explained this phenomenon by mentioning the well-known scattering cross section between neutrons and protons. At this early stage, he did not refer to the capture cross section by target nuclei. At the same time a thermodynamic approach to neutron-proton capture was being discussed by physicists: neutron capture was interpretated as the reverse of deuteron photodissociation and detailed balance among neutrons, protons, deuterons, and radiation was invoked. This thermodynamic approach might underlie Fermi's early explanation of the great efficiency of slow neutrons. Fermi repeatedly used a thermodynamic approach that had been used in describing some of the physical properties of conductors by Richardson and had been influential in Fermi's youth.

  12. Porphyrins for boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Gabel, Detlef

    1990-01-01

    Novel compounds for treatment of brain tumors in Boron Neutron Capture Therapy are disclosed. A method for preparing the compounds as well as pharmaceutical compositions containing said compounds are also disclosed. The compounds are water soluble, non-toxic and non-labile boronated porphyrins which show significant uptake and retention in tumors.

  13. Neutron transmission and capture of 241Am

    NASA Astrophysics Data System (ADS)

    Lampoudis, C.; Kopecky, S.; Plompen, A.; Schillebeeckx, P.; Wynants, R.; Gunsing, F.; Sage, C.; Bouland, O.; Noguere, G.

    2013-03-01

    A set of neutron transmission and capture experiments based on the Time Of Flight (TOF) technique, were performed in order to determine the 241Am capture cross section in the energy range from 0.01 eV to 1 keV. The GELINA facility of the Institute for Reference Materials and Measurements (IRMM) served as the neutron source. A pair of C6D6 liquid scintillators was used to register the prompt gamma rays emerging from the americium sample, while a Li-glass detector was used in the transmission setup. Results from the capture and transmission data acquired are consistent with each other, but appear to be inconsistent with the evaluated data files. Resonance parameters have been derived for the data up to the energy of 100 eV.

  14. Microdosimetry for Boron Neutron Capture Therapy

    SciTech Connect

    Maughan, R.L.; Kota, C.

    2000-09-05

    The specific aims of the research proposal were as follows: (1) To design and construct small volume tissue equivalent proportional counters for the dosimetry and microdosimetry of high intensity thermal and epithermal neutron beams used in BNCT, and of modified fast neutron beams designed for boron neutron capture enhanced fast neutron therapy (BNCEFNT). (2) To develop analytical methods for estimating the biological effectiveness of the absorbed dose in BNCT and BNCEFNT based on the measured microdosimetric spectra. (3) To develop an analytical framework for comparing the biological effectiveness of different epithermal neutron beams used in BNCT and BNCEFNT, based on correlated sets of measured microdosimetric spectra and radiobiological data. Specific aims (1) and (2) were achieved in their entirety and are comprehensively documented in Jay Burmeister's Ph.D. dissertation entitled ''Specification of physical and biologically effective absorbed dose in radiation therapies utilizing the boron neutron capture reaction'' (Wayne State University, 1999). Specific aim (3) proved difficult to accomplish because of a lack of sufficient radiobiological data.

  15. Design of multidirectional neutron beams for boron neutron capture synovectomy

    SciTech Connect

    Gierga, D.P.; Yanch, J.C.; Shefer, R.E.

    1997-12-01

    Boron neutron capture synovectomy (BNCS) is a potential application of the {sup 10}B(n, a) {sup 7}Li reaction for the treatment of rheumatoid arthritis. The target of therapy is the synovial membrane. Rheumatoid synovium is greatly inflamed and is the source of the discomfort and disability associated with the disease. The BNCS proposes to destroy the synovium by first injecting a boron-labeled compound into the joint space and then irradiating the joint with a neutron beam. This study discusses the design of a multidirectional neutron beam for BNCS.

  16. 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.

  17. Recent advances in neutron capture therapy (NCT)

    SciTech Connect

    Fairchild, R.G.

    1985-01-01

    The application of the /sup 10/B(n,..cap alpha..)/sup 7/Li reaction to cancer radiotherapy (Neutron Capture therapy, or NCT) has intrigued investigators since the discovery of the neutron. This paper briefly summarizes data describing recently developed boronated compounds with evident tumor specificity and extended biological half-lives. The implication of these compounds to NCT is evaluated in terms of Therapeutic Gain (TG). The optimization of NCT using band-pass filtered beams is described, again in terms of TG, and irradiation times with these less intense beams are estimated. 24 refs., 3 figs., 3 tabs.

  18. Slow neutron distribution in a temperature gradient

    SciTech Connect

    Molinari, V.G.; Pollachini, L.

    1985-12-01

    A set of equations that describes the diffusion of thermal neutrons is obtained from the energy-dependent Boltzmann equation. These equations are analogous to the phenomenological laws of the thermodynamic theory of irreversible processes and show, for instance, that as a temperatur gradient produces a neutron current (Soret effect), a density gradient yields an energy flow (Dufour effect). The method is applied to the ''two-temperature problem'' in order to gain better insight into the thermal diffusion phenomenon. The thermal diffusion of neutrons is shown to strongly depend on the scattering law of the two media where neutrons diffuse, and it is determined that some of the conclusions previously obtained are valid only for the case of a heavy gas moderator with the scat tering cross section independent of the energy.

  19. 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.

  20. A slow neutron polarimeter for the measurement of parity-odd neutron rotary power.

    PubMed

    Snow, W M; Anderson, E; Barrn-Palos, L; Bass, C D; Bass, T D; Crawford, B E; Crawford, C; Dawkins, J M; Esposito, D; Fry, J; Gardiner, H; Gan, K; Haddock, C; Heckel, B R; Holley, A T; Horton, J C; Huffer, C; Lieffers, J; Luo, D; Maldonado-Velzquez, M; Markoff, D M; Micherdzinska, A M; Mumm, H P; Nico, J S; Sarsour, M; Santra, S; Sharapov, E I; Swanson, H E; Walbridge, S B; Zhumabekova, V

    2015-05-01

    We present the design, description, calibration procedure, and an analysis of systematic effects for an apparatus designed to measure the rotation of the plane of polarization of a transversely polarized slow neutron beam as it passes through unpolarized matter. This device is the neutron optical equivalent of a crossed polarizer/analyzer pair familiar from light optics. This apparatus has been used to search for parity violation in the interaction of polarized slow neutrons in matter. Given the brightness of existing slow neutron sources, this apparatus is capable of measuring a neutron rotary power of d?/dz = 1 10(-7) rad/m. PMID:26026552

  1. A slow neutron polarimeter for the measurement of parity-odd neutron rotary power

    SciTech Connect

    Snow, W. M.; Anderson, E.; Bass, T. D.; Dawkins, J. M.; Fry, J.; Haddock, C.; Horton, J. C.; Luo, D.; Micherdzinska, A. M.; Walbridge, S. B.; Barrón-Palos, L.; Maldonado-Velázquez, M.; Bass, C. D.; Crawford, B. E.; Crawford, C.; Esposito, D.; Gardiner, H.; Gan, K.; Heckel, B. R.; Swanson, H. E. [University of Washington and others

    2015-05-15

    We present the design, description, calibration procedure, and an analysis of systematic effects for an apparatus designed to measure the rotation of the plane of polarization of a transversely polarized slow neutron beam as it passes through unpolarized matter. This device is the neutron optical equivalent of a crossed polarizer/analyzer pair familiar from light optics. This apparatus has been used to search for parity violation in the interaction of polarized slow neutrons in matter. Given the brightness of existing slow neutron sources, this apparatus is capable of measuring a neutron rotary power of dϕ/dz = 1 × 10{sup −7} rad/m.

  2. Non-Statistical Effects in Neutron Capture

    SciTech Connect

    Koehler, Paul Edward; Bredeweg, t a; Guber, Klaus H; Harvey, John A; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wiarda, Dorothea; Wouters, J. M.

    2009-01-01

    There have been many reports of non-statistical effects in neutron-capture measurements. However, reports of deviations of reduced-neutron-width ({Gamma}n{sup 0}) distributions from the expected Porter-Thomas (PT) shape largely have been ignored. Most of these deviations have been reported for odd-A nuclides. Because reliable spin (J) assignments have been absent for most resonances for such nuclides, it is possible that reported deviations from PT might be due to incorrect J assignments. We recently developed a new method for measuring spins of neutron resonances by using the DANCE detector at the Los Alamos Neutron Science Center (LANSCE). Measurements made with a 147Sm sample allowed us to determine spins of almost all known resonances below 1 keV. Furthermore, analysis of these data revealed that the {Gamma}n{sup 0} distribution was in good agreement with PT for resonances below 350 eV, but in disagreement with PT for resonances between 350 and 700 eV. Our previous (n,{alpha}) measurements had revealed that the {alpha} strength function also changes abruptly at this energy. There currently is no known explanation for these two non-statistical effects. Recently, we have developed another new method for determining the spins of neutron resonances. To implement this technique required a small change (to record pulse-height information for coincidence events) to a much simpler apparatus: A pair of C6D6 ?-ray detectors which we have employed for many years to measure neutron-capture cross sections at the Oak Ridge Electron Linear Accelerator (ORELA). Measurements with a 95Mo sample revealed that not only does the method work very well for determining spins, but it also makes possible parity assignments. Taken together, these new techniques at LANSCE and ORELA could be very useful for further elucidation of non-statistical effects.

  3. Non-Statistical Effects in Neutron Capture

    SciTech Connect

    Koehler, P. E.; Guber, K. H.; Harvey, J. A.; Wiarda, D.; Bredeweg, T. A.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.; Reifarth, R.

    2009-01-28

    There have been many reports of non-statistical effects in neutron-capture measurements. However, reports of deviations of reduced-neutron-width ({gamma}{sub n}{sup 0}) distributions from the expected Porter-Thomas (PT) shape largely have been ignored. Most of these deviations have been reported for odd-A nuclides. Because reliable spin (J) assignments have been absent for most resonances for such nuclides, it is possible that reported deviations from PT might be due to incorrect J assignments. We recently developed a new method for measuring spins of neutron resonances by using the DANCE detector at the Los Alamos Neutron Science Center (LANSCE). Measurements made with a {sup 147}Sm sample allowed us to determine spins of almost all known resonances below 1 keV. Furthermore, analysis of these data revealed that the {gamma}{sub n}{sup 0} distribution was in good agreement with PT for resonances below 350 eV, but in disagreement with PT for resonances between 350 and 700 eV. Our previous (n,{alpha}) measurements had revealed that the {alpha} strength function also changes abruptly at this energy. There currently is no known explanation for these two non-statistical effects. Recently, we have developed another new method for determining the spins of neutron resonances. To implement this technique required a small change (to record pulse-height information for coincidence events) to a much simpler apparatus: A pair of C{sub 6}D{sub 6}{gamma}-ray detectors which we have employed for many years to measure neutron-capture cross sections at the Oak Ridge Electron Linear Accelerator (ORELA). Measurements with a {sup 95}Mo sample revealed that not only does the method work very well for determining spins, but it also makes possible parity assignments. Taken together, these new techniques at LANSCE and ORELA could be very useful for further elucidation of non-statistical effects.

  4. Thermal Neutron Capture y's (CapGam)

    DOE Data Explorer

    The National Nuclear Data Center (NNDC) presents two tables showing energy and photon intensity with uncertainties of gamma rays as seen in thermal-neutron capture.  One table is organized in ascending order of gamma energy, and the second is organized by Z, A of the target. In the energy-ordered table the three strongest transitions are indicated in each case. The nuclide given is the target nucleus in the capture reaction. The gamma energies given are in keV. The gamma intensities given are relative to 100 for the strongest transition. %Iγ (per 100 n-captures) for the strongest transition is given, where known. All data are taken from the Evaluated Nuclear Structure Data File (ENSDF), a computer file of evaluated nuclear structure data and from the eXperimental Unevaluated Nuclear Data List (XUNDL). (Specialized Interface)

  5. Thermal Neutron Capture y's (CapGam)

    DOE Data Explorer

    The National Nuclear Data Center (NNDC) presents two tables showing energy and photon intensity with uncertainties of gamma rays as seen in thermal-neutron capture. One table is organized in ascending order of gamma energy, and the second is organized by Z, A of the target. In the energy-ordered table the three strongest transitions are indicated in each case. The nuclide given is the target nucleus in the capture reaction. The gamma energies given are in keV. The gamma intensities given are relative to 100 for the strongest transition. %I? (per 100 n-captures) for the strongest transition is given, where known. All data are taken from the Evaluated Nuclear Structure Data File (ENSDF), a computer file of evaluated nuclear structure data and from the eXperimental Unevaluated Nuclear Data List (XUNDL). (Specialized Interface)

  6. Preparation of radioactive rare earth targets for neutron capture study

    SciTech Connect

    Miller, G. G.; Rogers, P. S. Z.; Palmer, P. D.; Dry, D. E.; Rundberg, R. S.; Fowler, Malcolm M.; Wilhelmy, J. B.

    2002-01-01

    The understanding of thc details of nucleosynthesis in stars remains a great challenge. Though the basic mechanisms governing the processes have been known since the pioneering work of Burbidge, Burbidge, Fowler and Hoyle (l), we are now evolving into a condition where we can ask more specific questions. Of particular interest are the dynamics of the s ('slow') process. In this process the general condition is one in which sequential neutron captures occur at time scales long compared with the beta decay half lives of the capturing nuclides. The nucleosynthesis period for C or Ne burning stellar shells is believed to be in the year to few year time frame (2). This means that radionuclides with similar half lives to this burning period serve as 'branch point' nuclides. That is, there will be a competition between a capture to the next heavier isotope and a beta decay to the element of nexl higher atomic number. By understanding the abundances of these competing reactions we can learn about the dynamics of the nucleosynthesis process in the stellar medium. Crucial to this understanding is that we have a knowledge of the underlying neutron reaction cross sections on these unstable nuclides in the relevant stellar energy regions (neutrons of 0.1-100 KeV). Tm (1.9 years) and ls'Sm (90 ycws) have decay properties that permit their handling in an open fume hood. These Iwo were therefore selected to be the first radionuclides for neutron capture study in what will be an ongoing effort.

  7. Boron neutron capture therapy (BNCT): A radiation oncology perspective

    SciTech Connect

    Dorn, R.V. III Idaho National Engineering Lab., Idaho Falls, ID )

    1994-03-30

    Boron neutron capture therapy (BNCT) offers considerable promise in the search for the ideal cancer therapy, a therapy which selectively and maximally damages malignant cells while sparing normal tissue. This bimodal treatment modality selectivity concentrates a boron compound in malignant cells, and then [open quotes]activates[close quotes] this compound with slow neutrons resulting in a highly lethal event within the cancer cell. This article reviews this treatment modality from a radiation oncology, biology, and physics perspective. The remainder of the articles in this special issue provide a survey of the current [open quotes]state-of-the-art[close quotes] in this rapidly expanding field, including information with regard to boron compounds and their localization. 118 refs., 3 figs.

  8. Neutron tube design study for boron neutron capture therapy application

    SciTech Connect

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

    1999-05-06

    Radio-frequency (RF) driven ion sources are being developed in Lawrence Berkeley National Laboratory (LBNL) for sealed-accelerator-tube neutron generator application. By using a 5-cm-diameter RF-driven multicusp source H{sup +} yields over 95% have been achieved. These experimental findings will enable one to develop compact neutron generators based on the D-D or D-T fusion reactions. In this new neutron generator, the ion source, the accelerator and the target are all housed in a sealed metal container without external pumping. Recent moderator design simulation studies have shown that 14 MeV neutrons could be moderated to therapeutically useful energy ranges for boron neutron capture therapy (BNCT). The dose near the center of the brain with optimized moderators is about 65% higher than the dose obtained from a typical neutron spectrum produced by the Brookhaven Medical Research Reactor (BMRR), and is comparable to the dose obtained by other accelerator-based neutron sources. With a 120 keV and 1 A deuteron beam, a treatment time of {approx}35 minutes is estimated for BNCT.

  9. Thermal neutron capture gamma-rays

    SciTech Connect

    Tuli, J.K.

    1983-01-01

    The energy and intensity of gamma rays as seen in thermal neutron capture are presented. Only those (n,..cap alpha..), E = thermal, reactions for which the residual nucleus mass number is greater than or equal to 45 are included. These correspond to evaluations published in Nuclear Data Sheets. The publication source data are contained in the Evaluated Nuclear Structure Data File (ENSDF). The data presented here do not involve any additional evaluation. Appendix I lists all the residual nuclides for which the data are included here. Appendix II gives a cumulated index to A-chain evaluations including the year of publication. The capture gamma ray data are given in two tables - the Table 1 is the list of all gamma rays seen in (n,..gamma..) reaction given in the order of increasing energy; the Table II lists the gamma rays according to the nuclide.

  10. Liposomal boron delivery for neutron capture therapy.

    PubMed

    Nakamura, Hiroyuki

    2009-01-01

    Tumor cell destruction in boron neutron capture therapy (BNCT) is due to the nuclear reaction between (10)B and thermal neutrons. The thermal neutrons have an energy of 0.025 eV, clearly below the threshold energy required to ionize tissue components. However, neutron capture by (10)B produces lithium ion and helium (alpha-particles), which are high linear energy transfer (LET) particles, and dissipate their kinetic energy before traveling one cell diameter (5-9 microm) in biological tissues, ensuring their potential for precise cell killing. BNCT has been applied clinically for the treatment of malignant brain tumors, malignant melanoma, head and neck cancer, and hepatoma using two boron compounds: sodium borocaptate (Na(2)(10)B(12)H(11)SH; Na(2)(10)BSH) and l-p-boronophenylalanine (l-(10)BPA). These low molecular weight compounds are cleared easily from the cancer cells and blood. Therefore, high accumulation and selective delivery of boron compounds into tumor tissues are most important to achieve effective BNCT and to avoid damage of adjacent healthy cells. Much attention has been focused on the liposomal drug delivery system (DDS) as an attractive, intelligent technology of targeting and controlled release of (10)B compounds. Two approaches have been investigated for incorporation of (10)B into liposomes: (1) encapsulation of (10)B compounds into liposomes and (2) incorporation of (10)B-conjugated lipids into the liposomal bilayer. Our laboratory has developed boron ion cluster lipids for application of the latter approach. In this chapter, our boron lipid liposome approaches as well as recent developments of the liposomal boron delivery system are summarized. PMID:19913168

  11. Neutron Capture Cross Section of 239Pu

    NASA Astrophysics Data System (ADS)

    Mosby, S.; Arnold, C.; Bredeweg, T. A.; Couture, A.; Jandel, M.; O'Donnell, J. M.; Rusev, G.; Ullmann, J. L.; Chyzh, A.; Henderson, R.; Kwan, E.; Wu, C. Y.

    2014-09-01

    The 239Pu(n,γ) cross section has been measured over the energy range 10 eV - 10 keV using the Detector for Advanced Neutron Capture Experiments (DANCE) as part of a campaign to produce precision (n,γ) measurements on 239Pu in the keV region. Fission coincidences were measured with a PPAC and used to characterize the prompt fission γ-ray spectrum in this region. The resulting spectra will be used to better characterize the fission component of another experiment with a thicker target to extend the (n,γ) cross section measurement well into the keV region.

  12. Neutron Capture Cross Section of 239Pu

    NASA Astrophysics Data System (ADS)

    Mosby, S.; Arnold, C.; Bredeweg, T. A.; Chyzh, A.; Couture, A.; Henderson, R.; Jandel, M.; Kwan, E.; O'Donnell, J. M.; Rusev, G.; Ullmann, J. L.; Wu, C. Y.

    2014-05-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used to measure the 239Pu(n,?) cross section from 10 eV to the keV region. Three experimental run conditions were used to characterize the prompt fission ?-ray spectrum across the entire energy regime, measure the cross section in the resolved resonance region, and obtain necessary count rate well into the keV region. The preliminary cross sections are in good agreement with current evaluations from 10 eV to 80 keV.

  13. Slow Neutron Velocity Spectrometer Transmission Studies Of Pu

    DOE R&D Accomplishments Database

    Havens, W. W. Jr.; Melkonian, E.; Rainwater, L. J.; Levin, M.

    1951-05-28

    The slow neutron transmission of several samples of Pu has been investigated with the Columbia Neutron Velocity Spectrometer. Data are presented in two groups, those covering the energy region from 0 to 6 ev, and those covering the region above 6 ev. Below 6 ev the resolution was relatively good, and a detailed study of the cross section variation was made. Work above 6 ev consisted of merely locating levels and obtaining a rough idea of their strengths.

  14. Neutronic effects on tungsten-186 double neutron capture

    NASA Astrophysics Data System (ADS)

    Garland, Marc Alan

    Rhenium-188, a daughter product of tungsten-188, is an isotope of great interest in therapeutic nuclear medicine, being used in dozens of laboratory and clinical investigations worldwide. Applications include various cancer therapy strategies, treatment of rheumatoid arthritis, prevention of restenosis following coronary artery angioplasty, and palliation of bone pain associated with cancer metastases. With its half-life of 17 hours, 2.12 MeV (maximum) beta-particle emission, chemical similarity to technetium-99m (the most widely used diagnostic radioisotope), and its availability in a convenient tungsten-188/rhenium-188 generator system, rhenium-188 is a superb candidate for a broad range of applications. Production of 188W is typically via double neutron capture by 186W in a high flux nuclear reactor, predominantly the High Flux Isotope Reactor at the Oak Ridge National Laboratory in Tennessee. Experience at HFIR has shown that production yields (measured in Ci of 188W produced per g of 186W target) decrease considerably as target size increases. While the phenomenon of neutron resonance self-shielding would be expected to produce such an effect, temperature effects on neutron flux distribution and neutron capture rates may also be involved. Experimental investigations of these phenomena have not been previously performed. The work presented in this thesis evaluates the factors that contribute to the decrease in 188W yield from both theoretical and experimental standpoints. Neutron self-shielding and temperature effects were characterized to develop a strategy for target design that would optimize production yield, an important factor in minimizing health care costs. It was determined that decrease in yield due to neutron self-shielding can be attributed to depletion of epithermal neutrons at resonant energies, most significantly within the initial 0.4 mm depth of the target. The results from these studies further show that 188W yield in the interior of the target (beyond 0.4 mm depth) does not decrease as would be expected due to neutron attenuation. This observation was explained by the fact elevated temperatures in the interior of the target result in an increase in the 188W yield through Doppler broadening of cross sections, compensating for reduced yield due to neutron attenuation. Finally, this work supports earlier analyses that questioned the accuracy of the 187W thermal cross section and resonance integral.

  15. Research needs for neutron capture therapy

    SciTech Connect

    1995-12-01

    Key issues and questions addressed by the workshop related to optimization of Boron Neutron Capture Therapy (BNCT), in general, and to the possibility of success of the present BNCT trials at Brookhaven National Laboratory (BNL) and Massachusetts Institute of Technology (MIT), in particular. Both trials use nuclear fission reactors as neutron sources for BNCT of glioblastoma multiforme (BNL) and of deep seated melanoma (MIT). Presentations and discussions focussed on optimal boron-labeled compounds, mainly for brain tumors such as glioblastoma multiforme, and the best mode of compound delivery to the tumor. Also, optimizing neutron irradiation with dose delivery to the tumor cells and the issues of dosimetry of BNCT especially in the brain were discussed. Planning of treatment and of follow-up of patients, coordination of BNCT at various treatment sites, and the potential of delivering BNCT to various types of cancer with an appropriately tailored protocol were additional issues. The need for multicentric interdisciplinary cooperation among the different medical specialties was highlighted.

  16. Recent developments in neutron capture therapy.

    PubMed

    Fairchild, R G; Wheeler, F; Slatkin, D N; Coderre, J; Micca, P; Laster, B; Kahl, S B; Som, P; Fand, I

    1989-04-01

    The conditions for the possible initiation of clinical trials with neutron capture therapy at a number of locations in the U.S. is reviewed. There are several new technical developments or plans at the Brookhaven Medical Research Reactor (BMRR), the Power Burst Facility (PBF) at INEL, the Massachusetts Institute of Technology Reactor (MITR) and the Georgia Institute of Technology Research Reactor (GTRR). Emphasis is on the development of epithermal beams for the treatment of deepseated tumors with neutron fluxes in between 10(9) to 10(10) n/cm2s. Therapeutic dose gains, defined as the ratio of tumour dose to maximum normal tissue dose in the treatment volume are expected to be between 2 and 4, depending on the degree of suppression of fast neutron dose. Boron concentrations considered in this case in the tumour are around 35 micrograms 10B/g and tumour/normal tissue concentrations are around 10. The compound development throughout three generations is discussed. The compound proposed nowadays, Na2B12H11SH (or BSH), employed in the treatments in Japan, will likely be replaced in the future by analogous of biomolecules being enriched in the tumour by physiological pathways. Examples are p-boronophenylalanine or boronated porphyrius. The most promising solution envisaged would be the employment of tumour cell specific brononated monoclonal antibodies. Finally the mode of therapy is discussed which will likely be based on a fractioned scheme, to achieve optimized results. PMID:2711346

  17. Neutron Capture Experiments on Unstable Nuclei

    SciTech Connect

    Schwantes, Jon M.; Sudowe, Ralf; Folden, Charles M., III; Nitsche, Heino; Hoffman, Darleane C.

    2005-01-15

    The overall objective of this project is the measurement of neutron capture cross sections of importance to stewardship science and astrophysical modeling of nucleosynthesis, while at the same time helping to train the next generation of scientists with expertise relevant to U.S. national nuclear security missions and to stewardship science. A primary objective of this project is to study neutron capture cross sections for various stable and unstable isotopes that will contribute to the Science Based Stockpile Stewardship (SBSS) program by providing improved data for modeling and interpretation of nuclear device performance. Much of the information obtained will also be important in astrophysical modeling of nucleosynthesis. Measurements of these neutron capture cross sections are being conducted in collaboration with researchers at the Los Alamos Neutron Science Center (LANSCE) facility using the unique Detector for Advanced Neutron Capture Experiments (DANCE). In our early discussions with the DANCE group, decisions were made on the first cross sections to be measured and how our expertise in target preparation, radiochemical separations chemistry, and data analysis could best be applied. The initial emphasis of the project was on preparing suitable targets of both natural and separated stable europium isotopes in preparation for the ultimate goal of preparing a sufficiently large target of radioactive 155Eu (t1/2 = 4.7 years) and other radioactive and stable species for neutron cross-section measurements at DANCE. Our Annual Report, ''Neutron Capture Experiments on Unstable Nuclei'' by J. M. Schwantes, R. Sudowe, C. M. Folden III, H. Nitsche, and D. C. Hoffman, submitted to NNSA in December 2003, gives details about the initial considerations and scope of the project. During the current reporting period, electroplated targets of natural Eu together with valuable, stable, and isotopically pure 151Eu and 153Eu, and isotopically separated 154Sm were measured for the first time at the DANCE facility in early 2004. The Eu targets, suitable blanks, Be backing foils, and standards had been sent to the DANCE group in early fall 2003. Some preliminary data analysis was performed and more sophisticated analysis has begun. We developed plans for a suitable computer system for data analysis within our group at Berkeley and had meetings with counterparts at Lawrence Livermore National Laboratory (LLNL) and LANL concerning analysis of these data. Our major emphasis in 2004 has been to develop the separations and processes ultimately required to prepare radioactive targets of 4.7-year 155Eu. Efforts continued to devise an optimum multiprocess procedure suitable for use in separating radioactive 155Eu already produced by irradiation of stable 154Sm in a high neutron flux reactor at the Institut Laue-Langevin in France and shipped to LANL (the 22-min 155Sm neutron-capture product decays to 155Eu). This separation is extremely demanding because the highly radioactive 155Eu must be isolated from about 20 times as much mass of samarium before a target can be prepared for DANCE measurements. After all the procedures have been fully tested the radioactive 155Eu will be separated. The same electroplating methods already used successfully to prepare stable Eu isotope targets will be used to prepare the 155Eu target for DANCE. Discussions were held with LANL radiochemists in the Chemistry (C) Division about appropriate facilities at LANL for conducting the full-scale separation and purification of the radioactive targets. Three more multiprocess separations were developed that generated less chemical and radioactive waste, but they must still be adapted for processing hundred-milligram quantities. Until these separations can be successfully implemented at this scale, standard HPLC procedures will be used for separating and preparing radioactive 155Eu, 2.6-year 147Pm, and 1.9-year 171Tm target materials. Future directions beyond the preparation of radioactive lanthanide targets include closer collaboration with both LLNL and LANL to prepare actinide targets such as plutonium, americium, and curium. Also, the applicability of established and novel techniques will be evaluated for rapid separations of Am and Cm required in the irradiation of 241Am. Lastly, we will conduct a series of experiments aimed at enhancing current methods used to electrodeposit lanthanide and actinide targets on thin Ti and Be backings.

  18. Neutron Capture Experiments Using the DANCE Array at Los Alamos

    SciTech Connect

    Dashdorj, D.; Mitchell, G. E.; Baramsai, B.; Chyzh, A.; Walker, C.; Agvaanluvsan, U.; Becker, J. A.; Parker, W.; Sleaford, B.; Wu, C. Y.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.; Krticka, M.; Becvar, F.

    2009-03-31

    The Detector for Advanced Neutron Capture Experiments (DANCE) is designed for neutron capture measurements on very small and/or radioactive targets. The DANCE array of 160 BaF{sub 2} scintillation detectors is located at the Lujan Center at the Los Alamos Neutron Science Center (LANSCE). Accurate measurements of neutron capture data are important for many current applications as well as for basic understanding of neutron capture. The gamma rays following neutron capture reactions have been studied by the time-of-flight technique using the DANCE array. The high granularity of the array allows measurements of the gamma-ray multiplicity. The gamma-ray multiplicities and energy spectra for different multiplicities can be measured and analyzed for spin and parity determination of the resolved resonances.

  19. Progress in neutron capture therapy for cancer

    SciTech Connect

    Allen, B.J.; Harrington, B.V. ); Moore, D.E. )

    1992-01-01

    Prognosis for some cancers is good, but for others, few patients will survive 12 months. This latter group of cancers is characterised by a proclivity to disseminate malignant cells in the host organ. In some cases systemic metastases occur, but in other cases, failure to achieve local control results in death. First among these cancers are the high grade brain tumours, astrocytoma 3,4 and glioblastoma multiforme. Local control of these tumors should lead to cure. Other cancers melanoma metastatic to the brain, for which a useful palliative therapy is not yet available, and pancreatic cancer for which localised control at an early stage could bring about improved prognosis. Patients with these cancers have little grounds for hope. Our primary objective is to reverse this situation with Neutron Capture Therapy (NCT). The purpose of this fourth symposium is to hasten the day whereby patients with these cancers can reasonably hope for substantial remissions.

  20. Progress in neutron capture therapy for cancer

    SciTech Connect

    Allen, B.J.; Harrington, B.V.; Moore, D.E.

    1992-09-01

    Prognosis for some cancers is good, but for others, few patients will survive 12 months. This latter group of cancers is characterised by a proclivity to disseminate malignant cells in the host organ. In some cases systemic metastases occur, but in other cases, failure to achieve local control results in death. First among these cancers are the high grade brain tumours, astrocytoma 3,4 and glioblastoma multiforme. Local control of these tumors should lead to cure. Other cancers melanoma metastatic to the brain, for which a useful palliative therapy is not yet available, and pancreatic cancer for which localised control at an early stage could bring about improved prognosis. Patients with these cancers have little grounds for hope. Our primary objective is to reverse this situation with Neutron Capture Therapy (NCT). The purpose of this fourth symposium is to hasten the day whereby patients with these cancers can reasonably hope for substantial remissions.

  1. Detector for advanced neutron capture experiments at LANSCE

    SciTech Connect

    Ullmann, J. L.; Reifarth, R.; Haight, Robert C.; Hunt, L. F.; O'Donnell, J. M.; Bredeweg, T. A.; Wilhelmy, J. B.; Fowler, Malcolm M.; Vieira, D. J.; Wouters, J. M.; Strottman, D.; Kaeppeler, F.; Heil, M.; Chamberlin, E. P.

    2002-01-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 159-element 4x barium fluoride array designed to study neutron capture on small quantities, 1 mg or less, of radioactive nuclides. It is being built on a 20 m neutron flight path which views the 'upper tier' water moderator at the Manuel J. Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center. The detector design is based on Monte Carlo calculations which have suggested ways to minimize backgrounds due to neutron scattering events. A data acquisition system based on fast transient digitizers is bcing implemented

  2. The Detector for Advanced Neutron Capture Experiments at LANSCE

    SciTech Connect

    Ullmann, J.L.; Reifarth, R.; Haight, R.C.; Hunt, L.; O'Donnell, J.M.; Rundberg, R.S.; Bredeweg, T.A.; Wilhelmy, J.B.; Fowler, M.M.; Vieira, D.J.; Wouters, J.M.; Strottman, D.D.; Kaeppeler, F.; Heil, M.; Chamberlin, E.P.

    2003-08-26

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 159-element 4{pi} barium fluoride array designed to study neutron capture on small quantities, 1 mg or less, of radioactive nuclides. It is being built on a 20 m neutron flight path which views the 'upper tier' water moderator at the Manuel J. Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center. The detector design is based on Monte Carlo calculations which have suggested ways to minimize backgrounds due to neutron scattering events. A data acquisition system based on fast transient digitizers is being implemented.

  3. Detecting energy dependent neutron capture distributions in a liquid scintillator

    NASA Astrophysics Data System (ADS)

    Balmer, Matthew J. I.; Gamage, Kelum A. A.; Taylor, Graeme C.

    2015-03-01

    A novel technique is being developed to estimate the effective dose of a neutron field based on the distribution of neutron captures in a scintillator. Using Monte Carlo techniques, a number of monoenergetic neutron source energies and locations were modelled and their neutron capture response was recorded. Using back propagation Artificial Neural Networks (ANN) the energy and incident direction of the neutron field was predicted from the distribution of neutron captures within a 6Li-loaded liquid scintillator. Using this proposed technique, the effective dose of 252Cf, 241AmBe and 241AmLi neutron fields was estimated to within 30% for four perpendicular angles in the horizontal plane. Initial theoretical investigations show that this technique holds some promise for real-time estimation of the effective dose of a neutron field.

  4. Neutron capture therapy: Years of experimentation---Years of reflection

    SciTech Connect

    Farr, L.E.

    1991-12-16

    This report describes early research on neutron capture therapy over a number of years, beginning in 1950, speaking briefly of patient treatments but dwelling mostly on interpretations of our animal experiments. This work carried out over eighteen years, beginning over forty years ago. Yet, it is only fitting to start by relating how neutron capture therapy became part of Brookhaven's Medical Research Center program.

  5. Neutron Capture Cross Sections of 236U and 234U

    SciTech Connect

    Rundberg, R. S.; Bredeweg, T. A.; Bond, E. M.; Haight, R. C.; Hunt, L. F.; O'Donnell, J. M.; Schwantes, J. M.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Kronenberg, A.

    2006-03-13

    Accurate neutron capture cross sections of the actinide elements at neutron energies up to 1 MeV are needed to better interpret archived nuclear test data, for post-detonation nuclear attribution, and the Advanced Fuel Cycle Initiative. The Detector for Advance Neutron Capture Experiments, DANCE, has unique capabilities that allow the differentiation of capture gamma rays from fission gamma rays and background gamma rays from scattered neutrons captured by barium isotopes in the barium fluoride scintillators. The DANCE array has a high granularity, 160 scintillators, high efficiency, and nearly 4-{pi} solid angle. Through the use of cuts in cluster multiplicity and calorimetric energy the capture gamma-rays are differentiated from other sources of gamma rays. The preliminary results for the capture cross sections of 236U are in agreement with the ENDF/B-VI evaluation. The preliminary results for 234U lower are than ENDF/B-VI evaluation and are closer to older evaluations.

  6. Neutron capture therapy with deep tissue penetration using capillary neutron focusing

    DOEpatents

    Peurrung, Anthony J.

    1997-01-01

    An improved method for delivering thermal neutrons to a subsurface cancer or tumor which has been first doped with a dopant having a high cross section for neutron capture. The improvement is the use of a guide tube in cooperation with a capillary neutron focusing apparatus, or neutron focusing lens, for directing neutrons to the tumor, and thereby avoiding damage to surrounding tissue.

  7. Thermal neutron capture cross sections of tellurium isotopes

    SciTech Connect

    Tomandl, I.; Honzatko, J.; von Egidy, T.; Wirth, H.-F.; Belgya, T.; Lakatos, M.; Szentmiklosi, L.; Revay, Zs.; Molnar, G.L.; Firestone, R.B.; Bondarenko, V.

    2004-03-01

    New values for thermal neutron capture cross sections of the tellurium isotopes 122Te, 124Te, 125Te, 126Te, 128Te, and 130Te are reported. These values are based on a combination of newly determined partial g-ray cross sections obtained from experiments on targets contained natural Te and gamma intensities per capture of individual Te isotopes. Isomeric ratios for the thermal neutron capture on the even tellurium isotopes are also given.

  8. Neutron Capture Experiments on Unstable Nuclei

    SciTech Connect

    Jon M. Schwantes; Ralf Sudowe; Heino Nitsche; Darleane C. Hoffman

    2003-12-16

    A primary objective of this project is to study neutron capture cross sections for various stable and unstable isotopes that will contribute to the Science Based Stockpile Stewardship (SBSS) program by providing improved data for modeling and interpretation of nuclear device performance. The information obtained will also be important in astrophysical modeling of nucleosynthesis. During this reporting period, the emphasis has been on preparing a radioactive target of {sup 155}Eu (half-life = 4.7 years), and several stable targets, including isotopically separated {sup 154}Sm, {sup 151}Eu, and {sup 153}Eu. Measurements of their neutron capture cross sections will be conducted in collaboration with researchers at the Los Alamos Neutron Science Center (LANSCE) facility using the Detector for Advanced Neutron Capture Experiments (DANCE). A suitable backing material (beryllium) for the targets has been selected after careful calculations of its contribution to the background of the measurements. In addition, a high voltage plating procedure has been developed and optimized. Stable targets of {sup 151}Eu and {sup 153}Eu and a target of natural Eu ({approx}50% {sup 151}Eu and {approx}50% {sup 153}Eu) have each been plated to a mass thickness of >1 mg/cm{sup 2} and delivered to the DANCE collaboration at Los Alamos National Laboratory (LANL). Natural Eu targets will be tested first to confirm that the target dimensions and backing are appropriate prior to performing measurements on the extremely valuable targets of separated isotopes. In order to prepare a target of the radioactive {sup 155}Eu, it must first be separated from the {sup 154}Sm target material that was irradiated in a very high neutron flux of 1.5x1015 neutrons/cm{sup 2}/s for 50 days. The reaction is {sup 154}Sm (n,f){sup 155}Sm (half-life = 22 minutes) {sup 155}Eu. Considerable progress has been made in developing a suitable high-yield and high-purity separation method for separating Eu from targets containing about twenty times as much Sm. An exhaustive review of the literature indicated that a multiprocess approach in which Eu(III) is reduced to Eu(II) prior to separation should provide an effective and efficient means of separation from the Sm(III). To date, three multiprocess methods have been developed and tested for their ability to meet the design requirements set forth by this project. These methods combine an initial reduction step using Zn(Hg) with either cation exchange resin in (1) column form or in (2) a batch reactor and hydroxyisobutyrate (?-HIB) as the eluant for trivalent lanthanides. Another multiprocess method uses solvent extraction with 0.1 M thenoyl trifluoroacetone (TTA) in benzene. Preliminary experiments indicate that: (a) A multiprocess approach using ?-HIB as a complexing agent for trivalent lanthanides is ineffective for separating Eu from Sm because ?-HIB stabilizes Eu(III) even in the presence of excess amounts of the reductant; (b) A multiprocess approach using solvent extraction shows promise, indicating that 0.1 M TTA in benzene favors extraction of trivalent over divalent metal ions by a factor of greater than 750. However, the reduction step using Zn(Hg), when combined with the TTA extraction, becomes less effective at reducing Eu during subsequent extractions and may also affect the stability of the TTA. Use of the amalgam also introduces Zn(II) contamination that must be separated from the Eu with additional solvent extraction steps. A PhD student from the group has visited the LANSCE facility, participated in several parameter checks of the DANCE, and acquainted himself with the data acquisition system. During these initial experiments, data were collected and brought back to UC Berkeley for analysis. A high purity P-type germanium detector was purchased, set up, and calibrated to assist with the determination of separation yields and efficiencies using ?-ray spectroscopy measurements of suitable radioactive tracers.

  9. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1997-03-18

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  10. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1997-08-05

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  11. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, M.; Slatkin, D.N.

    1995-10-03

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na{sub 4}B{sub 12}I{sub 11}SSB{sub 12}I{sub 11}, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy. 1 fig.

  12. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1997-03-18

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  13. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1995-10-03

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  14. Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    1997-08-05

    A method for performing boron neutron capture therapy for the treatment of tumors is disclosed. The method includes administering to a patient an iodinated sulfidohydroborane, a boron-10-containing compound. The site of the tumor is localized. by visualizing the increased concentration of the iodine labelled compound at the tumor. The targeted tumor is then irradiated with a beam of neutrons having an energy distribution effective for neutron capture. Destruction of the tumor occurs due to high LET particle irradiation of the tissue secondary to the incident neutrons being captured by the boron-10 nuclei. Iodinated sulfidohydroboranes are disclosed which are especially suitable for the method of the invention. In a preferred embodiment, a compound having the formula Na.sub.4 B.sub.12 I.sub.11 SSB.sub.12 I.sub.11, or another pharmaceutically acceptable salt of the compound, may be administered to a cancer patient for boron neutron capture therapy.

  15. Radiative neutron capture cross sections on 176Lu at DANCE

    NASA Astrophysics Data System (ADS)

    Roig, O.; Jandel, M.; Méot, V.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Keksis, A. L.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.

    2016-03-01

    The cross section of the neutron capture reaction 176Lu(n ,γ ) has been measured for a wide incident neutron energy range with the Detector for Advanced Neutron Capture Experiments at the Los Alamos Neutron Science Center. The thermal neutron capture cross section was determined to be (1912 ±132 ) b for one of the Lu natural isotopes, 176Lu. The resonance part was measured and compared to the Mughabghab's atlas using the R -matrix code, sammy. At higher neutron energies the measured cross sections are compared to ENDF/B-VII.1, JEFF-3.2, and BRC evaluated nuclear data. The Maxwellian averaged cross sections in a stellar plasma for thermal energies between 5 keV and 100 keV were extracted using these data.

  16. Neutron Capture Reactions on lu Isotopes at Dance

    NASA Astrophysics Data System (ADS)

    Roig, O.; Meot, V.; Daugas, J.-M.; Morel, P.; Jandel, M.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Haight, R. C.; Keksis, A. L.; Rundberg, R. S.; Ullmann, J. L.; Wouters, J. M.

    2013-03-01

    The DANCE1 (Detector for Advanced Neutron Capture Experiments) array at LANSCE spallation neutron source in Los Alamos has been used to obtain the neutron radiative capture cross sections for 175Lu and 176Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process.2,3 Three targets were used to perform these measurements. One was natural Lu foil of 31 mg/cm2 and the other two were isotope-enriched targets of 175Lu and 176Lu. Firstly, the cross sections were obtained by normalizing yield to a well-known cross section at the thermal neutron energy. Now, we want to obtain absolute cross sections of radiative capture through a precise neutron flux determination, an accurate target mass measurement and an efficiency determination of the DANCE array.

  17. Lunar neutron capture as a tracer for regolith dynamics

    NASA Technical Reports Server (NTRS)

    Burnett, D. S.; Woolum, D. S.

    1974-01-01

    The Apollo 17 Lunar Neutron Probe Experiment measured both the boron-10 neutron capture rate and the uranium-235 neutron-induced fission rate as a function of depth. Cd absorption gave a measure of the neutron energy spectrum. Comparisons of the results are made with theory, and good agreement is obtained for the magnitudes and depth dependences of the capture rates. While the low-energy neutron spectrum at depth agrees with theory, the spectrum near the peak of the flux profile is harder than predicted. In light of these results, several alternatives for interpreting the magnitude and uniformity of the neutron capture data from lunar surface soil samples are outlined. While none of the alternatives can be unquestionably defended or discarded, a surface layer mixing model is discussed in detail.

  18. Neutron Capture Gamma-Ray Libraries for Nuclear Applications

    SciTech Connect

    Sleaford, B W; Firestone, R B; Summers, N; Escher, J; Hurst, A; Krticka, M; Basunia, S; Molnar, G; Belgya, T; Revay, Z; Choi, H D

    2010-11-04

    The neutron capture reaction is useful in identifying and analyzing the gamma-ray spectrum from an unknown assembly as it gives unambiguous information on its composition. this can be done passively or actively where an external neutron source is used to probe an unknown assembly. There are known capture gamma-ray data gaps in the ENDF libraries used by transport codes for various nuclear applications. The Evaluated Gamma-ray Activation file (EGAF) is a new thermal neutron capture database of discrete line spectra and cross sections for over 260 isotopes that was developed as part of an IAEA Coordinated Research project. EGAF is being used to improve the capture gamma production in ENDF libraries. For medium to heavy nuclei the quasi continuum contribution to the gamma cascades is not experimentally resolved. The continuum contains up to 90% of all the decay energy and is modeled here with the statistical nuclear structure code DICEBOX. This code also provides a consistency check of the level scheme nuclear structure evaluation. The calculated continuum is of sufficient accuracy to include in the ENDF libraries. This analysis also determines new total thermal capture cross sections and provides an improved RIPL database. For higher energy neutron capture there is less experimental data available making benchmarking of the modeling codes more difficult. They are investigating the capture spectra from higher energy neutrons experimentally using surrogate reactions and modeling this with Hauser-Feshbach codes. This can then be used to benchmark CASINO, a version of DICEBOX modified for neutron capture at higher energy. This can be used to simulate spectra from neutron capture at incident neutron energies up to 20 MeV to improve the gamma-ray spectrum in neutron data libraries used for transport modeling of unknown assemblies.

  19. Neutron capture experiments with 4π DANCE Calorimeter

    NASA Astrophysics Data System (ADS)

    Baramsai, B.; Mitchel, G. E.; Walker, C. L.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J.; Vieira, D. J.; Agvaanluvsan, U.; Dashdorj, D.; Tseren, T.; Bečvář, F.; Krtička, M.

    2012-02-01

    In recent years we have performed a series of neutron capture experiments with the DANCE detector array located at the Los Alamos Neutron Science Center. The radiative decay spectrum from the compound nucleus contains important information about nuclear structure and the reaction mechanism. The primary goals of the measurements are to obtain improved capture cross sections, to determine properties of the photon strength function, to improve neutron level densities and strength functions by determining the spin and parity of the capturing states. We shall present examples of our recent results.

  20. Enhancing the Detector for Advanced Neutron Capture Experiments

    NASA Astrophysics Data System (ADS)

    Couture, A.; Mosby, S.; Baramsai, B.; Bredeweg, T. A.; Jandel, M.; Macon, K.; O'Donnell, J. M.; Rusev, G.; Taddeucci, T. N.; Ullmann, J. L.; Walker, C. L.

    2015-05-01

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. The upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons.

  1. Enhancing the detector for advanced neutron capture experiments

    SciTech Connect

    Couture, A.; Mosby, S.; Baramsai, B.; Bredeweg, T. A.; Jandel, M.; Macon, K.; O’Donnell, J. M.; Rusev, G.; Taddeucci, T. N; Ullmann, J. L.; Walker, C. L.

    2015-05-28

    The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. The upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons.

  2. Cross section expansion for direct neutron radiative capture

    SciTech Connect

    Baye, D.

    2004-07-01

    Cross sections for neutron radiative capture multiplied by the relative velocity can be expressed as a Taylor expansion in powers of the relative energy. The coefficients of this expansion are expressed in the potential model as integrals involving solutions of the radial Schroedinger equation and of its inhomogeneous energy derivatives calculated at zero energy. Similarities and differences with charged-particle capture are emphasized. The {sup 12}C(n,{gamma}){sup 13}C capture reaction is treated as an example. The coefficients of the Taylor expansion lead to simple parametrizations of the experimental partial cross sections for neutron capture to each {sup 13}C bound state.

  3. Sensitivity studies for the weak r process: neutron capture rates

    SciTech Connect

    Surman, R.; Mumpower, M.; Sinclair, R.; Jones, K. L.; Hix, W. R.; Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 ; McLaughlin, G. C.

    2014-04-15

    Rapid neutron capture nucleosynthesis involves thousands of nuclear species far from stability, whose nuclear properties need to be understood in order to accurately predict nucleosynthetic outcomes. Recently sensitivity studies have provided a deeper understanding of how the r process proceeds and have identified pieces of nuclear data of interest for further experimental or theoretical study. A key result of these studies has been to point out the importance of individual neutron capture rates in setting the final r-process abundance pattern for a ‘main’ (A ∼ 130 peak and above) r process. Here we examine neutron capture in the context of a ‘weak’ r process that forms primarily the A ∼ 80 r-process abundance peak. We identify the astrophysical conditions required to produce this peak region through weak r-processing and point out the neutron capture rates that most strongly influence the final abundance pattern.

  4. Neutron capture therapy: Years of experimentation---Years of reflection

    SciTech Connect

    Farr, L.E.

    1991-12-16

    This report describes early research on neutron capture therapy over a number of years, beginning in 1950, speaking briefly of patient treatments but dwelling mostly on interpretations of our animal experiments. This work carried out over eighteen years, beginning over forty years ago. Yet, it is only fitting to start by relating how neutron capture therapy became part of Brookhaven`s Medical Research Center program.

  5. Cosmogenic neutron-capture-produced nuclides in stony meteorites

    SciTech Connect

    Spergel, M.S.; Reedy, R.C.; Lazareth, O.W.; Levy, P.W.

    1985-01-01

    The distribution of neutrons with energies below 15 MeV in spherical stony meteoroids is calculated using the ANISN neutron-transport code. The source distributions and intensities of neutrons are calculated using cross sections for the production of tritium. The meteoroid's radius and chemical composition strongly influence the total neutron flux and the neutron energy spectrum, while the location within a meteoroid only affects the relative neutron intensities. Meteoroids need to have radii of more than 50 g/cm/sup 2/ before they have appreciable fluxes of neutrons near thermal energies. Meteoroids with high hydrogen or low iron contents can thermalize neutrons better than chondrites. Rates for the production of /sup 60/Co, /sup 59/Ni, and /sup 36/Cl are calculated with evaluated neutron-capture cross sections and neutron fluxes determined for carbonaceous chondrites with high hydrogen contents, L-chondrites, and aubrites. For most meteoroids with radii < 300 g/cm/sup 2/, the production rates of these neutron-capture nuclides increase monotonically with depth. The highest calculated /sup 60/Co production rate in an ordinary chondrite is 375 atoms/(min g-Co) at the center of a meteoroid with a 250 g/cm/sup 2/ radius. The production rates calculated for spallogenic /sup 60/Co and /sup 59/Ni are greater than the neutron-capture rates for radii less than approx.50-75 g/cm/sup 2/. Only for very large meteoroids and chlorine-rich samples is the neutron-capture production of /sup 36/Cl important. The results of these calculations are compared with those of previous calculations and with measured activities in many meteorites. 44 refs., 15 figs., 1 tab.

  6. Cosmogenic neutron-capture-produced nuclides in stony meteorites

    SciTech Connect

    Spergel, M.S.; Reedy, R.C.; Lazareth, O.W.; Levy, P.W.; Slatest, L.A.

    1986-03-30

    The distribution of neutrons with energies below 15 MeV in spherical stony meteoroids is calculated using the ANISN neutron-transport code. The source distributions and intensities of neutrons are calculated using cross sections for the production of tritium. The meteoroid's radius and chemical composition strongly influence the total neutron flux and the neutron energy spectrum, whereas the location within a meteoroid only affects the relative neutron intensities. Meteoroids must have radii of more than 50 g/cm/sup 2/ before they have appreciable fluxes of neutrons near thermal energies. Meteoroids with high hydrogen or low iron contents can thermalize neutrons better than chondrites can. Rates for the production of /sup 60/Co, /sup 59/Ni, and /sup 36/Cl are calculated with these neutron fluxes and evaluated neutron-capture cross sections and are reported for carbonaceous chondrites with high hydrogen contents, L-chondrites, and aubrites. For most meteoroids with radii <300 g/cm/sup 2/, the production rates of these neutron-capture nuclides increase monotonically with depth. The highest calculated /sup 60/Co production rate in an ordinary chondrite is 375 atoms/min/g-Co at the center of a meteoroid with a 250 g/cm/sup 2/ radius. The production rates calculated for spallogenic /sup 60/Co and /sup 59/Ni are greater than the neutron-capture rates for radii less than approx.50-75 g/cm/sup 2/. Only for very large meteoroids and chlorine-rich samples is the neutron-capture production of /sup 36/Cl important. The results of these calculations are compared with those of previous calculations and with measured activities in many meteorites.

  7. NSTARA capture gated plastic neutron detector

    NASA Astrophysics Data System (ADS)

    Pawe?czak, I. A.; Tke, J.; Henry, E.; Quinlan, M.; Singh, H.; Schrder, W. U.

    2011-02-01

    NSTAR (Neutron Sandwich Transmuter/Activation- ? Radiator) prototypes were developed and their performances were evaluated using radioactive sources and a pulsed neutron beam. The NSTAR operating principle is similar to that of Gd-loaded liquid scintillation detectors, where the scintillator has dual functions as neutron moderator and sensor of delayed capture ?-rays, but spatially separates scintillator from neutron converter components. The time dependent NSTAR response to neutrons consists of a prompt, energy related light flash followed by a delayed signal characteristic in both light output and delay time. This feature allows one to discriminate on average between neutrons and ?-rays and provides the basis for multiplicity determination. The detectors are scalable, economic to construct of environmentally benign components, and can be ruggedized. Prototype detector modules consist of 1220(50 or 100) cm 3 stacks of plastic scintillator slabs (Saint Gobain BC-408) alternating with thin Gd converter films viewed by fast photomultipliers (Philips XP2041). The effective Gd/scintillator ratio is 0.5 wt%. Results of tests of NSTAR with 252Cf and neutrons from the D(d,n) 3He reactions are in good agreement with theoretical estimates based on neutron transport simulations. Characteristics of the detector module include an average neutron capture time of =21.70.2 ?s and a detection efficiency of ?=263% for DD neutrons. The NSTAR has been applied to determine the multiplicity distribution of neutrons produced in D(d,n) 3He reactions by a neutron generator.

  8. Review of the neutron capture process in fission reactors

    SciTech Connect

    Poenitz, W.P.

    1981-07-01

    The importance of the neutron capture process and the status of the more important cross section data are reviewed. The capture in fertile and fissile nuclei is considered. For thermal reactors the thermal to epithermal capture ratio for /sup 238/U and /sup 232/Th remains a problem though some improvements were made with more recent measurements. The capture cross section of /sup 238/U in the fast energy range remains quite uncertain and a long standing discrepancy for the calculated versus experimental central reaction rate ratio C28/F49 persists. Capture in structural materials, fission product nuclei and the higher actinides is also considered.

  9. Neutron capture therapy with deep tissue penetration using capillary neutron focusing

    DOEpatents

    Peurrung, A.J.

    1997-08-19

    An improved method is disclosed for delivering thermal neutrons to a subsurface cancer or tumor which has been first doped with a dopant having a high cross section for neutron capture. The improvement is the use of a guide tube in cooperation with a capillary neutron focusing apparatus, or neutron focusing lens, for directing neutrons to the tumor, and thereby avoiding damage to surrounding tissue. 1 fig.

  10. DANCEing with the Stars: Measuring Neutron Capture on Unstable Isotopes with DANCE

    SciTech Connect

    Couture, A.; Bond, E.; Bredeweg, T. A.; Fowler, M.; Haight, R. C.; Jandel, M.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.; Agvaanluvsan, U.; Becker, J. A.; Baker, J. D.; Bayarbadrahk, B.; Chyzh, A.; Dashdorj, D.; Reifarth, R.

    2009-03-10

    Isotopes heavier than iron are known to be produced in stars through neutron capture processes. Two major processes, the slow (s) and rapid (r) processes are each responsible for 50% of the abundances of the heavy isotopes. The neutron capture cross sections of the isotopes on the s process path reveal information about the expected abundances of the elements as well as stellar conditions and dynamics. Until recently, measurements on unstable isotopes, which are most important for determining stellar temperatures and reaction flow, have not been experimentally feasible. The Detector for Advance Neutron Capture Experiments (DANCE) located at the Los Alamos Neutron Science Center (LANSCE) was designed to perform time-of-flight neutron capture measurements on unstable isotopes for nuclear astrophysics, stockpile stewardship, and reactor development. DANCE is a 4-{pi}BaF{sub 2} scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

  11. DANCEing with the Stars: Measuring Neutron Capture on Unstable Isotopes with DANCE

    NASA Astrophysics Data System (ADS)

    Couture, A.; Agvaanluvsan, U.; Baker, J. D.; Bayarbadrahk, B.; Becker, J. A.; Bond, E.; Bredeweg, T. A.; Chyzh, A.; Dashdorj, D.; Fowler, M.; Haight, R. C.; Jandel, M.; Keksis, A. L.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.

    2009-03-01

    Isotopes heavier than iron are known to be produced in stars through neutron capture processes. Two major processes, the slow (s) and rapid (r) processes are each responsible for 50% of the abundances of the heavy isotopes. The neutron capture cross sections of the isotopes on the s process path reveal information about the expected abundances of the elements as well as stellar conditions and dynamics. Until recently, measurements on unstable isotopes, which are most important for determining stellar temperatures and reaction flow, have not been experimentally feasible. The Detector for Advance Neutron Capture Experiments (DANCE) located at the Los Alamos Neutron Science Center (LANSCE) was designed to perform time-of-flight neutron capture measurements on unstable isotopes for nuclear astrophysics, stockpile stewardship, and reactor development. DANCE is a 4-π BaF2 scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

  12. Neutron capture and fission in /sup 254g/ Es

    SciTech Connect

    Halperin, J.; Bigelow, J.E.; O'Kelley, G.D.; Oliver, J.H.; Wiggins, J.T.

    1985-07-01

    Integral neutron capture and neutron fission cross sections have been measured for the 276-day /sup 254g/ Es. Thermal cross sections and resonance integrals were evaluated using a cadmium filter technique. Capture cross sections were determined from alpha-particle spectrum measurements following neutron irradiations with cobalt flux monitors. Fission cross sections were measured using fission track detection techniques with STTU monitors. The fission cross-section values compared favorably with an absorption cross-section determination from a burnout experiment of SVTEs-SVUEs. The integral neutron capture and fission cross sections determined for /sup 254g/ Es are: sigma /sub c/ /sup th/ = 28.3 + or - 2.5 and I /sub c/ = 18.2 + or - 1.5 b, and sigma /sub F/ /sup th/ = 1970 + or - 200 and I /sub F/ = 1200 + or - 250 b.

  13. In Vivo Boron Uptake Determination for Boron Neutron Capture Synovectomy

    SciTech Connect

    Binello, Emanuela; Shortkroff, Sonya; Yanch, Jacquelyn C.

    1999-06-06

    Boron neutron capture synovectomy (BNCS) has been proposed as a new application of the boron neutron capture reaction for the treatment of rheumatoid arthritis. In BNCS, a boron compound is injected into the joint space, where it is taken up by the synovium. The joint is then irradiated with neutrons of a desired energy range, inducing the boron neutron capture reaction in boron-loaded cells. Boron uptake by the synovium is an important parameter in the assessment of the potential of BNCS and in the determination of whether to proceed to animal irradiations for the testing of therapeutic efficacy. We present results from an investigation of boron uptake in vivo by the synovium.

  14. Proton linacs for boron neutron capture therapy

    SciTech Connect

    Lennox, A.J. |

    1993-08-01

    Recent advances in the ability to deliver boron-containing drugs to brain tumors have generated interest in {approximately}4 MeV linacs as sources of epithermal neutrons for radiation therapy. In addition, fast neutron therapy facilities have been studying methods to moderate their beams to take advantage of the high cross section for epithermal neutrons on boron-10. This paper describes the technical issues involved in each approach and presents the motivation for undertaking such studies using the Fermilab linac. the problems which must be solved before therapy can begin are outlined. Status of preparatory work and results of preliminary measurements are presented.

  15. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    SciTech Connect

    Grammer, K. B.; Alarcon, R.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; Fry, J.; Gericke, M.; Gillis, R. C.; Greene, G. L.; Hamblen, J.; Hayes, C.; Kucuker, S.; Mahurin, R.; Maldonado-Velázquez, M.; Martin, E.; McCrea, M.; Mueller, P. E.; Musgrave, M.; Nann, H.; Penttilä, S. I.; Snow, W. M.; Tang, Z.; Wilburn, W. S.

    2015-05-08

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g(r) inferred from neutron scattering measurements of the differential cross section dσ/dΩ from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. Furthermore, we describe our measurements and compare them with previous work.

  16. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    DOE PAGESBeta

    Grammer, K. B.; Alarcon, R.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; et al

    2015-05-08

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g(r) inferred from neutron scattering measurements of the differential cross section dσ/dΩ from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component)more » using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. Furthermore, we describe our measurements and compare them with previous work.« less

  17. Measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

    NASA Astrophysics Data System (ADS)

    Grammer, K. B.; Alarcon, R.; Barrón-Palos, L.; Blyth, D.; Bowman, J. D.; Calarco, J.; Crawford, C.; Craycraft, K.; Evans, D.; Fomin, N.; Fry, J.; Gericke, M.; Gillis, R. C.; Greene, G. L.; Hamblen, J.; Hayes, C.; Kucuker, S.; Mahurin, R.; Maldonado-Velázquez, M.; Martin, E.; McCrea, M.; Mueller, P. E.; Musgrave, M.; Nann, H.; Penttilä, S. I.; Snow, W. M.; Tang, Z.; Wilburn, W. S.

    2015-05-01

    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many-body physics. Unfortunately, the pair correlation function g (r ) inferred from neutron scattering measurements of the differential cross section d/σ d Ω from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43 and 16.1 meV on liquid hydrogen at 15.6 K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1 meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra nonequilibrium component of orthohydrogen. Liquid parahydrogen is also a widely used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. We describe our measurements and compare them with previous work.

  18. Neutron capture reactions on Lu isotopes at DANCE

    NASA Astrophysics Data System (ADS)

    Roig, O.; Jandel, M.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Couture, A. J.; Daugas, J.-M.; Haight, R. C.; Keksis, A. L.; Méot, V.; Morel, P.; O'Donnell, J. M.; Rundberg, R. S.; Taylor, W. A.; Ullmann, J. L.; Wouters, J. M.

    2010-03-01

    The DANCE (Detector for Advanced Neutron Capture Experiments) array located at the Los Alamos national laboratory has been used to obtain the neutron capture cross sections for the 175Lu and 176Lu isotopes with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the nucleosynthesis s-process in astrophysics and for applications as in reactor physics or in nuclear medicine. Three targets were used to perform these measurements. One was natLu foil and the other two were isotope-enriched targets of 175Lu and 176Lu. The cross sections are obtained for now through a precise neutron flux determination and a normalization at the thermal neutron cross section value. A comparison with the recent experimental data and the evaluated data of ENDF/B-VII.0 will be presented. In addition, resonances parameters and spin assignments for some resonances will be featured.

  19. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    SciTech Connect

    Scott Wilde, Raymond Keegan

    2008-07-01

    The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

  20. FAST NEUTRON SPECTROMETER USING SPACED SEMICONDUCTORS FOR MEASURING TOTAL ENERGY OF NEUTRONS CAPTURED

    DOEpatents

    Love, T.A.; Murray, R.B.

    1964-04-14

    A fast neutron spectrometer was designed, which utilizes a pair of opposed detectors having a layer of /sup 6/LiF between to produce alpha and T pair for each neutron captured to provide signals, which, when combined, constitute a measure of neutron energy. (AEC)

  1. Thermal-neutron capture for A=26-35

    SciTech Connect

    Chunmei, Z.; Firestone, R.B.

    2001-06-01

    The prompt gamma-ray data of thermal- neutron captures fornuclear mass number A=26-35 had been evaluated and published in "ATOMICDATA AND NUCLEAR DATA TABLES, 26, 511 (1981)". Since that time themanyexperimental data of the thermal-neutron captures have been measuredand published. The update of the evaluated prompt gamma-ray data is verynecessary for use in PGAA of high-resolution analytical prompt gamma-rayspectroscopy. Besides, the evaluation is also very needed in theEvaluated Nuclear Structure Data File, ENSDF, because there are no promptgamma-ray data in ENSDF. The levels, prompt gamma-rays and decay schemesof thermal-neutron captures for nuclides (26Mg, 27Al, 28Si, 29Si, 30Si,31P, 32S, 33S, 34S, and 35Cl) with nuclear mass number A=26-35 have beenevaluated on the basis of all experimental data. The normalizationfactors, from which absolute prompt gamma-ray intensity can be obtained,and necessary comments are given in the text. The ENSDF format has beenadopted in this evaluation. The physical check (intensity balance andenergy balance) of evaluated thermal-neutron capture data has been done.The evaluated data have been put into Evaluated Nuclear Structure DataFile, ENSDF. This evaluation may be considered as an update of the promptgamma-ray from thermal-neutron capture data tables as published in"ATOMIC DATA AND NUCLEAR DATA TABLES, 26, 511 (1981)".

  2. Thermal-neutron capture for A=36-44

    SciTech Connect

    Chunmei, Z.; Firestone, R.B.

    2003-01-01

    The prompt gamma-ray data of thermal- neutron captures fornuclear mass number A=26-35 had been evaluated and published in "ATOMICDATA AND NUCLEAR DATA TABLES, 26, 511 (1981)". Since that time the manyexperimental data of the thermal-neutron captures have been measured andpublished. The update of the evaluated prompt gamma-ray data is verynecessary for use in PGAA of high-resolution analytical prompt gamma-rayspectroscopy. Besides, the evaluation is also very needed in theEvaluated Nuclear Structure Data File, ENSDF, because there are no promptgamma-ray data in ENSDF. The levels, prompt gamma-rays and decay schemesof thermal-neutron captures fornuclides (26Mg, 27Al, 28Si, 29Si, 30Si,31P, 32S, 33S, 34S, and 35Cl) with nuclear mass number A=26-35 have beenevaluated on the basis of all experimental data. The normalizationfactors, from which absolute prompt gamma-ray intensity can be obtained,and necessary comments are given in the text. The ENSDF format has beenadopted in this evaluation. The physical check (intensity balance andenergy balance) of evaluated thermal-neutron capture data has been done.The evaluated data have been put into Evaluated Nuclear Structure DataFile, ENSDF. This evaluation may be considered as an update of the promptgamma-ray from thermal-neutron capture data tables as published in"ATOMIC DATA AND NUCLEAR DATA TABLES, 26, 511 (1981)".

  3. Neutron capture strategy and technique developments for GNEP

    SciTech Connect

    Couture, Aaron Joseph

    2008-01-01

    The initial three years of neutron capture measurements have been very successful in providing data for the Advanced Fuel Cycle Initiative/Global Nuclear Energy Partnership (AFCI/GNEP) program. Now that the most straightforward measurements have been completed, additional technical challenges face future measurements. In particular, techniques are needed to perform measurements that exhibit at least one of three major problems -- large fission:capture ratios, large capture:capture ratios, and high intrinsic activity samples. This paper will set forward a plan for attacking these technical challenges and moving forward with future measurements.

  4. Developments in Accelerator Based Boron Neutron Capture Therapy

    NASA Astrophysics Data System (ADS)

    Green, Stuart

    1998-06-01

    This paper will review the current status of Boron Neutron Capture Therapy (BNCT), from basic physical mechanisms and clinical indications, to neutron beam development and dosimetry. For in-hospital facilities, particle accelerators presently provide the favoured option, and this paper concentrates on this approach to neutron beam production for BNCT. Various accelerator-based approaches will be reviewed, but discussion will concentrate on the Birmingham programme, particularly the design of a suitable neutron beam delivery system and the experimental validation of Monte Carlo simulations on a mock-up neutron beam moderation system. The use of dose modifying factors to evaluate the likely clinical utility of an epithermal neutron beam will also be discussed, with illustrations from the Birmingham programme.

  5. Neutron Capture and Fission Measurement on ^238Pu at DANCE

    NASA Astrophysics Data System (ADS)

    Chyzh, Andrii; Wu, Ching-Yen; Kwan, Elaine; Henderson, Roger; Gostic, Jolie; Couture, Aaron; Young, Hye; Ullmann, John; O'Donnell, John; Jandel, Marian; Haight, Robert; Bredeweg, Todd

    2012-10-01

    Neutron capture and fission reactions on actinides are important in nuclear engineering and physics. DANCE (Detector for Advanced Neutron Capture Measurement, LANL) combined with PPAC (avalanche technique based fission tagging detector, LLNL) were used to study the neutron capture reactions in ^238Pu. Because of extreme spontaneous α-radioactivity in ^238Pu and associated safety issues, 3 separate experiments were performed in 2010-2012. The 1st measurement was done without fission tagging on a 396-μg thick target. The 2nd one was with PPAC on the same target. The 3rd final measurement was done on a thin target with a mass of 40 μg in order to reduce α-background load on PPAC. This was the first such measurement in a laboratory environment. The absolute ^238Pu(n,γ) cross section is presented together with the prompt γ-ray multiplicity in the ^238Pu(n,f) reaction.

  6. Studies of collision mechanisms in electron capture by slow multiply charged ions

    NASA Astrophysics Data System (ADS)

    Gilbody, H. B.; McCullough, R. W.

    2004-01-01

    We review measurements based on translational energy spectroscopy which are being used to identify and assess the relative importance of the various collision mechanisms involved in one-electron capture by slow multiply charged ions in collisions with simple atoms and molecules.

  7. Thermal neutron capture cross section of the radioactive isotope 60Fe

    NASA Astrophysics Data System (ADS)

    Heftrich, T.; Bichler, M.; Dressler, R.; Eberhardt, K.; Endres, A.; Glorius, J.; Göbel, K.; Hampel, G.; Heftrich, M.; Käppeler, F.; Lederer, C.; Mikorski, M.; Plag, R.; Reifarth, R.; Stieghorst, C.; Schmidt, S.; Schumann, D.; Slavkovská, Z.; Sonnabend, K.; Wallner, A.; Weigand, M.; Wiehl, N.; Zauner, S.

    2015-07-01

    Background: Fifty percent of the heavy element abundances are produced via slow neutron capture reactions in different stellar scenarios. The underlying nucleosynthesis models need the input of neutron capture cross sections. Purpose: One of the fundamental signatures for active nucleosynthesis in our galaxy is the observation of long-lived radioactive isotopes, such as 60Fe with a half-life of 2.60 ×106 yr. To reproduce this γ activity in the universe, the nucleosynthesis of 60Fe has to be understood reliably. Methods: An 60Fe sample produced at the Paul Scherrer Institut (Villigen, Switzerland) was activated with thermal and epithermal neutrons at the research reactor at the Johannes Gutenberg-Universität Mainz (Mainz, Germany). Results: The thermal neutron capture cross section has been measured for the first time to σth=0.226 (-0.049+0.044) b . An upper limit of σRI<0.50 b could be determined for the resonance integral. Conclusions: An extrapolation towards the astrophysically interesting energy regime between k T =10 and 100 keV illustrates that the s -wave part of the direct capture component can be neglected.

  8. Investigation of neutron beams for the realization of boron neutron capture therapy.

    PubMed

    Csom, G; Zsolnay, E M; Szondi, E J

    1990-01-01

    Results of the initial theoretical and experimental work performed at the Institute of Nuclear Technics of the Budapest Technical University (BTU NTI) regarding the design of a pure thermal neutron field for neutron capture therapy experiments are reported. Calculations show that a thermal neutron flux of approximately 10(9) neutrons cm-2s-1 will be generated using a filter made of graphite and bismuth. PMID:2268235

  9. Post-AGB stars in the Magellanic Clouds and neutron-capture processes in AGB stars

    NASA Astrophysics Data System (ADS)

    Lugaro, M.; Campbell, S. W.; Van Winckel, H.; De Smedt, K.; Karakas, A. I.; Käppeler, F.

    2015-11-01

    Aims: We explore modifications to the current scenario for the slow neutron-capture process (the s-process) in asymptotic giant branch (AGB) stars to account for the Pb deficiency observed in post-AGB stars of low metallicity ([Fe/H] ≃-1.2) and low initial mass (≃ 1-1.5 M⊙) in the Large and Small Magellanic Clouds. Methods: We calculated the stellar evolution and nucleosynthesis for a 1.3 M⊙ star with [Fe/H] = -1.3 and tested different amounts and distributions of protons leading to the production of the main neutron source within the 13C-pocket and proton ingestion scenarios. Results: No s-process models can fully reproduce the abundance patterns observed in the post-AGB stars. When the Pb production is lowered, the abundances of the elements between Eu and Pb, such as Er, Yb, W, and Hf, are also lowered to below those observed. Conclusions: Neutron-capture processes with neutron densities intermediate between the s and the rapid neutron-capture processes may provide a solution to this problem and be a common occurrence in low-mass, low-metallicity AGB stars.

  10. Progress on the Europium Neutron-Capture Study using DANCE

    SciTech Connect

    Agvaanluvsan, U; Becker, J A; Macri, R A; Parker, W; Wilk, P; Wu, C Y; Bredeweg, T A; Esch, E; Haight, R C; O'Donnell, J M; Reifarth, R; Rundberg, R S; Schwantes, J M; Ullmann, J L; Vieira, D J; Wilhelmy, J B; Wouters, J M; Mitchell, G E; Sheets, S A; Becvar, F; Krticka, M

    2006-09-05

    The accurate measurement of neutron-capture cross sections of the Eu isotopes is important for many reasons including nuclear astrophysics and nuclear diagnostics. Neutron capture excitation functions of {sup 151,153}Eu targets were measured recently using a 4{pi} {gamma}-ray calorimeter array DANCE located at the Los Alamos Neutron Science Center for E{sub n} = 0.1-100 keV. The progress on the data analysis efforts is given in the present paper. The {gamma}-ray multiplicity distributions for the Eu targets and Be backing are significantly different. The {gamma}-ray multiplicity distribution is found to be the same for different neutron energies for both {sup 151}Eu and {sup 153}Eu. The statistical simulation to model the {gamma}-ray decay cascade is summarized.

  11. Neutron Capture Effects and Radionuclei in the Early Solar Nebula

    NASA Astrophysics Data System (ADS)

    Hua, X.-M.; Lingenfelter, R. E.; Marti, K.; ?ytkow, A. N.

    2000-03-01

    We consider the particle radiation environment in the early solar system that might result from low-energy cosmic-ray acceleration in active star-forming regions and explore the possibility that neutron capture-produced radionuclei could account for some of the ``fossil'' isotopic anomalies in meteorites. We calculate the effects of possible low-energy cosmic-ray nuclear interactions 4.56 Gyr ago on the evolving solar nebula and compare the predictions with the ``fossil'' records of possible neutron-induced fission products and extinct radionuclides observed in meteorites. We conclude that the external irradiation of the early solar nebula by low-energy cosmic-ray particle fluxes generated by supernovae in a star formation region cannot produce the neutron fluences of about 3x1016 n cm-2 that would be required to account for the possible neutron capture isotopic anomalies in meteoritic samples.

  12. Neutron capture on Sm-149 in lunar samples.

    NASA Technical Reports Server (NTRS)

    Russ, G. P., III; Burnett, D. S.; Wasserburg, G. J.; Lingenfelter, R. E.

    1971-01-01

    High precision isotopic composition measurements of Sm have been carried out for two terrestrial and seven lunar samples from three Apollo sites. The lunar samples, selected to show a wide variation in cosmic ray exposure ages, have a wide range of enrichments in Sm-150/Sm-154 (up to 0.8%) and depletions in Sm-149/Sm-154 which are due to neutron capture. The ratio of the number of neutrons captured per atom by Sm-149 to Gd-157 is 0.9 and reflects a hardened lunar neutron spectrum. This ratio is in reasonable but not exact agreement with that obtained from the theoretical lunar neutron energy spectrum of Lingenfelter, Canfield and Hampel. The average composition for terrestrial samarium is given.

  13. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    SciTech Connect

    Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Couture, A.; Haight, R. C.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Stoyer, M. A.; Wu, C. Y.; Becker, J. A.; Haslett, R. J.; Henderson, R. A.

    2009-01-28

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 10 eV and 250 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented where the fission events were actively triggered during the experiments. In these experiments, a Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) events from (n,f) events. The first direct observation of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  14. Neutron capture and neutron-induced fission experiments on americium isotopes with DANCE

    SciTech Connect

    Jandel, Marian

    2008-01-01

    Neutron capture cross section data on Am isotopes were measured using the Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory. The neutron capture cross section was determined for {sup 241}Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for {sup 243}Am for neutron energies between 35 eV and 200 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on {sup 242m}Am will be presented, where the fission events were actively triggered during the experiments. In these experiments, the Parallel-Plate Avalanche Counter (PPAC) detector that surrounds the target located in the center of the DANCE array was used as a fission-tagging detector to separate (n,{gamma}) from (n,f) events. The first evidence of neutron capture on {sup 242m}Am in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

  15. Sublethal and potentially lethal damage repair on thermal neutron capture therapy

    SciTech Connect

    Utsumi, H.; Ichihashi, M.; Kobayashi, T.; Elkind, M.M. )

    1989-07-01

    Tonicity shock or caffeine postirradiation treatment makes evident fast-type potentially lethal damage (PLD). Caffeine expresses fast-type PLD more efficiently than tonicity shock in X-irradiated B-16 mouse melanoma cells, compared with V79 Chinese hamster cells. The survival curves of thermal neutrons for either V79 or B-16 cells exhibit no shoulder. Neither V79 nor B-16 cells show the sublethal damage (SLD) repair of thermal neutrons. Caffeine-sensitive fast-type PLD repairs exist in X-irradiated B-16 cells, as well as V79 cells. The fast-type PLD repair of B-16 cells exposed to thermal neutrons alone is rather less than that of X-irradiated cells. Furthermore, an extremely low level of fast-type PLD repair of B-16 cells with 10B1-paraboronophenylalanine (BPA) preincubation (20 hours) followed by thermal neutron irradiation indicated that 10B(n,alpha)7Li reaction effectively eradicates actively growing melanoma cells. The plateau-phase B-16 cells are well able to repair the slow-type PLD of X-rays. However, cells can not repair the slow-type PLD induced by thermal neutron irradiation with or without 10B1-BPA preincubation. These results suggest that thermal neutron capture therapy can effectively kill radioresistant melanoma cells in both proliferating and quiescent phases.

  16. Neutron Capture Measurements on 97Mo with the DANCE Array

    NASA Astrophysics Data System (ADS)

    Walker, Carrie L.

    Neutron capture is a process that is crucial to understanding nucleosynthesis, reactors, and nuclear weapons. Precise knowledge of neutron capture cross-sections and level densities is necessary in order to model these high-flux environments. High-confidence spin and parity assignments for neutron resonances are of critical importance to this end. For nuclei in the A=100 mass region, the p-wave neutron strength function is at a maximum, and the s-wave strength function is at a minimum, producing up to six possible Jpi combinations. Parity determination becomes important to assigning spins in this mass region, and the large number of spin groups adds complexity to the problem. In this work, spins and parities for 97Mo resonances are assigned, and best fit models for photon strength function and level density are determined. The neutron capture-cross section for 97Mo is also determined, as are resonance parameters for neutron energies ranging from 16 eV to 2 keV.

  17. Neutron capture cross section of {sup 241}Am

    SciTech Connect

    Jandel, M.; Bredeweg, T. A.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O'Donnell, J. M.; Haight, R. C.; Kawano, T.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Agvaanluvsan, U.; Parker, W. E.; Wu, C. Y.; Becker, J. A.

    2008-09-15

    The neutron capture cross section of {sup 241}Am for incident neutrons from 0.02 eV to 320 keV has been measured with the detector for advanced neutron capture experiments (DANCE) at the Los Alamos Neutron Science Center. The thermal neutron capture cross section was determined to be 665{+-}33 b. Our result is in good agreement with other recent measurements. Resonance parameters for E{sub n}<12 eV were obtained using an R-matrix fit to the measured cross section. The results are compared with values from the ENDF/B-VII.0, Mughabghab, JENDL-3.3, and JEFF-3.1 evaluations. {gamma}{sub n} neutron widths for the first three resonances are systematically larger by 5-15% than the ENDF/B-VII.0 values. The resonance integral above 0.5 eV was determined to be 1553{+-}7 b. Cross sections in the resolved and unresolved energy regions above 12 eV were calculated using the Hauser-Feshbach theory incorporating the width-fluctuation correction of Moldauer. The calculated results agree well with the measured data, and the extracted averaged resonance parameters in the unresolved resonance region are consistent with those for the resolved resonances.

  18. Contribution of Massive Stars to the Production of Neutron Capture Elements

    NASA Astrophysics Data System (ADS)

    Federman, Steven

    2010-09-01

    Elements beyond the Fe-peak must be synthesized through neutron-capture processes. With the aim of understanding the contribution of massive stars to the synthesis of neutron-capture elements during the current epoch, we propose an archival survey of interstellar arsenic, cadmium, tin, and lead. Nucleosynthesis via the weak slow process and the rapid process are the routes involving massive stars, while the main slow process arises from the evolution of low-mass stars. Ultraviolet lines for the dominant ions for each element will be used to extract interstellar abundances. The survey involves about forty sight lines, many of which are associated with regions of massive star formation shaped by core-collapse supernovae {SNe II}. The sample will increase the number of published determinations by factors of 2 to 5. HST spectra are the only means for determining the elemental abundances for this set of species in diffuse interstellar clouds. The survey contains directions that are both molecule poor and molecule rich, thereby enabling us to examine the overall level of depletion onto grains as a function of gas density. Complementary laboratory determinations of oscillator strengths will place the interstellar measurements on an absolute scale. The results from the proposed study will be combined with published interstellar abundances for other neutron capture elements and the suite of measurements will be compared to results from stars throughout the history of the Galaxy.

  19. Thermal Neutron Capture Cross Section of {sup 22}Ne

    SciTech Connect

    Belgya, T.; Uberseder, E.; Petrich, D.; Kaeppeler, F.

    2009-01-28

    The radiative thermal neutron capture cross section of the astrophysically important {sup 22}Ne nucleus has been measured at the guided cold neutron beam of the Budapest Research Reactor. High-pressure gas-bottles filled with mixtures of enriched {sup 22}Ne and CH{sub 4} were used. The cross section was determined by means of the comparator method, and an improved decay-scheme obtained in this work. The new value for the thermal neutron cross section is 52.7{+-}0.7 mb, 18% larger than the accepted value. The influence of the new cross section on the astrophysical reaction rate is under investigation.

  20. Neutron capture cross section standards for BNL 325, Fourth Edition

    SciTech Connect

    Holden, N.E.

    1981-01-01

    This report evaluates the experimental data and recommends values for the thermal neutron cross sections and resonance integrals for the neutron capture reactions: /sup 55/Mn(n,..gamma..), /sup 59/Co(n,..gamma..) and /sup 197/Au(n,..gamma..). The failure of lithium and boron as standards due to the natural variation of the absorption cross sections of these elements is discussed. The Westcott convention, which describes the neutron spectrum as a thermal Maxwellian distribution with an epithermal component, is also discussed.

  1. Neutron capture reactions near the N =82 shell-closure

    NASA Astrophysics Data System (ADS)

    Dutta, Saumi; Chakraborty, Dipti; Gangopadhyay, G.; Bhattacharyya, Abhijit

    2016-02-01

    Neutron capture cross sections have been calculated in nuclei near the N =82 neutron shell-closure. These nuclei are of astrophysical interest, participating in the s -process and the p -process. A semimicroscopic optical model has been used with the potential being obtained through folding the target density with the DDM3Y nucleon-nucleon interaction. Theoretical density values have been calculated using the relativistic mean-field approach. The calculated cross sections, as a function of neutron energy, agree reasonably well with experimental measurements. Maxwellian-averaged cross sections, important for astrophysical processes, have been calculated.

  2. Proceedings of the first international symposium on neutron capture therapy

    SciTech Connect

    Fairchild, R.G.; Brownell, G.L.

    1982-01-01

    This meeting was arranged jointly by MIT and BNL in order to illuminate progress in the synthesis and targeting of boron compounds and to evaluate and document progress in radiobiological and dosimetric aspects of neutron capture therapy. It is hoped that this meeting will facilitate transfer of information between groups working in these fields, and encourage synergistic collaboration.

  3. Paired ion ESI of borane neutron capture agents

    SciTech Connect

    Singh, P.S.; Swenson, D.H.; Schweingruber, H.; Laine, R.A.

    1995-12-31

    Imidocaptate (IC) was developed for experimental boron neutron capture therapy for cancer. Electrospray ionization mass spectrometry (ESI-MS) was used to characterize the IC by using various counter ion pairs. The best results were obtained with ion paired with triethylamine, and tetraethylammonium cations.

  4. Neutron-capture nucleosynthesis in the first stars

    SciTech Connect

    Roederer, Ian U.; Preston, George W.; Thompson, Ian B.; Shectman, Stephen A.; Sneden, Christopher

    2014-04-01

    Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have observed 16 stars with enhanced carbon or nitrogen using the MIKE Spectrograph on the Magellan Telescopes at Las Campanas Observatory and the Tull Spectrograph on the Smith Telescope at McDonald Observatory. We present radial velocities, stellar parameters, and detailed abundance patterns for these stars. Strontium, yttrium, zirconium, barium, europium, ytterbium, and other heavy elements are detected. In four stars, these heavy elements appear to have originated in some form of r-process nucleosynthesis. In one star, a partial s-process origin is possible. The origin of the heavy elements in the rest of the sample cannot be determined unambiguously. The presence of elements heavier than the iron group offers further evidence that zero-metallicity rapidly rotating massive stars and pair instability supernovae did not contribute substantial amounts of neutron-capture elements to the regions where the stars in our sample formed. If the carbon- or nitrogen-enhanced metal-poor stars with low levels of neutron-capture elements were enriched by products of zero-metallicity supernovae only, then the presence of these heavy elements indicates that at least one form of neutron-capture reaction operated in some of the first stars.

  5. Direct Neutron Capture Calculations with Covariant Density Functional Theory Inputs

    NASA Astrophysics Data System (ADS)

    Zhang, Shi-Sheng; Peng, Jin-Peng; Smith, Michael S.; Arbanas, Goran; Kozub, Ray L.

    2014-09-01

    Predictions of direct neutron capture are of vital importance for simulations of nucleosynthesis in supernovae, merging neutron stars, and other astrophysical environments. We calculate the direct capture cross sections for E1 transitions using nuclear structure information from a covariant density functional theory as input for the FRESCO coupled-channels reaction code. We find good agreement of our predictions with experimental cross section data on the double closed-shell targets 16O, 48Ca, and 90Zr, and the exotic nucleus 36S. Extensions of the technique for unstable nuclei and for large-scale calculations will be discussed. Predictions of direct neutron capture are of vital importance for simulations of nucleosynthesis in supernovae, merging neutron stars, and other astrophysical environments. We calculate the direct capture cross sections for E1 transitions using nuclear structure information from a covariant density functional theory as input for the FRESCO coupled-channels reaction code. We find good agreement of our predictions with experimental cross section data on the double closed-shell targets 16O, 48Ca, and 90Zr, and the exotic nucleus 36S. Extensions of the technique for unstable nuclei and for large-scale calculations will be discussed. Supported by the U.S. Dept. of Energy, Office of Nuclear Physics.

  6. Three-port beam splitter for slow neutrons using holographic nanoparticle-polymer composite diffraction gratings

    SciTech Connect

    Klepp, J.; Fally, M.; Tomita, Y.; Pruner, C.; Kohlbrecher, J.

    2012-10-08

    Diffraction of slow neutrons by nanoparticle-polymer composite gratings has been observed. By carefully choosing grating parameters such as grating thickness and spacing, a three-port beam splitter operation for slow neutrons - splitting the incident neutron intensity equally into the {+-}1st and the 0th diffraction orders - has been realized. As a possible application, a Zernike three-path interferometer is briefly discussed.

  7. [Liposomal boron delivery system for neutron capture therapy].

    PubMed

    Nakamura, Hiroyuki

    2008-02-01

    Boron neutron capture therapy (BNCT) is a binary cancer treatment based on the nuclear reaction of two essentially nontoxic species, (10)B and thermal neutrons. High accumulation and selective delivery of boron into tumor tissue are the most important requirements to achieve efficient neutron capture therapy of cancers. This review focuses on the liposomal boron delivery system (BDS) as a recent promising approach that meets these requirements for BNCT. BDS involves two strategies: (1) encapsulation of boron in the aqueous core of liposomes and (2) accumulation of boron in the liposomal bilayer. Various boronated liposomes have been developed and significant boron accumulation into tumor tissue with high tumor/blood boron ratios has been achieved by BDS. PMID:18239367

  8. Neutron capture measurements on unstable nuclei at LANSCE

    SciTech Connect

    Ullmann, J. L.; Haight, R. C.; Fowler, M. M.; Miller, G. G.; Rundberg, R. S.; Wilhelmy, J. B.

    1999-06-10

    Although neutron capture by stable isotopes has been extensively measured, there are very few measurements on unstable isotopes. The intense neutron flux at the Manual Lujan Jr. Neutron Scattering Center at LANSCE enables us to measure capture on targets with masses of about 1 mg over the energy range from 1 eV to 100 keV. These measurements are important not only for understanding the basic physics, but also for calculations of stellar nucleosynthesis and Science-Based Stockpile Stewardship. Preliminary measurements on {sup 169}Tm and {sup 171}Tm have been made with deuterated benzene detectors. A new detector array at the Lujan center and a new radioactive isotope separator will combine to give Los Alamos a unique capability for making these measurements.

  9. Advancements in Tumor Targeting Strategies for Boron Neutron Capture Therapy.

    PubMed

    Luderer, Micah John; de la Puente, Pilar; Azab, Abdel Kareem

    2015-09-01

    Boron neutron capture therapy (BNCT) is a promising cancer therapy modality that utilizes the nuclear capture reaction of epithermal neutrons by boron-10 resulting in a localized nuclear fission reaction and subsequent cell death. Since cellular destruction is limited to approximately the diameter of a single cell, primarily only cells in the neutron field with significant boron accumulation will be damaged. However, the emergence of BNCT as a prominent therapy has in large part been hindered by a paucity of tumor selective boron containing agents. While L-boronophenylalanine and sodium borocaptate are the most commonly investigated clinical agents, new agents are desperately needed due to their suboptimal tumor selectivity. This review will highlight the various strategies to improve tumor boron delivery including: nucleoside and carbohydrate analogs, unnatural amino acids, porphyrins, antibody-dendrimer conjugates, cationic polymers, cell-membrane penetrating peptides, liposomes and nanoparticles. PMID:26033767

  10. Neutron Capture Measurements on Unstable Nuclei at LANSCE

    SciTech Connect

    Ullmann, J.; Haight, R.; Wilhelmy, J.; Fowler, M.; Rundberg, R.; Miller, G.

    1998-11-04

    Although neutron capture by stable isotopes has been extensively measured, there are very few measurements on unstable isotopes. The intense neutron flux at the Manual Lujan Jr. Neutron Scattering Center at LANSCE enables us to measure capture on targets with masses of about 1 mg over the energy range from 1 eV to 100 keV. These measurements are important not only for understanding the basic physics, but also for calculations of stellar nucleosynthesis and Science-Based Stockpile Stewardship. Preliminary measurements on {sup 169}Tm and {sup 171}Tm have been made with deuterated benzene detectors. A new detector array at the Lujan center and a new radioactive isotope separator will combine to give Los Alamos a unique capability for making these measurements.

  11. Current status of fast-neutron-capture calculations

    SciTech Connect

    Gardner, D.G.

    1982-04-15

    This work is primarily concerned with the calculation of neutron capture cross sections and capture gamma-ray spectra, in the framework of the Hauser-Feshbach statistical model and for neutrons from the resonance region up to several MeV. An argument is made that, for applied purposes such as constructing evaluated cross-section libraries, nonstatistical capture mechanisms may be completely neglected at low energies and adequately approximated at high energies in a simple way. The use of gamma-ray strength functions to obtain radiation widths is emphasized. Using the reaction /sup 89/Y + n as an example, the problems encountered in trying to construct a case that could be run equivalently on two different nuclear reaction codes are illustrated, and the effects produced by certain parameter variations are discussed.

  12. Correlated double electron capture in slow, highly charged ion-atom collisions

    SciTech Connect

    Stolterfoht, N.; Havener, C.C.; Phaneuf, R.A.; Swenson, J.K.; Shafroth, S.M.; Meyer, F.W.

    1986-01-01

    Recent measurements of autoionization electrons produced in slow, highly charged ion-atom collisions are reviewed. Mechanisms for double electron capture into equivalent and nonequivalent configurations are analyzed by comparing the probabilities for the creation of L/sub 1/L/sub 23/X Coster Kronig electrons and L-Auger electrons. It is shown that the production of the Coster-Kronig electrons is due to electron correlation effects whose analysis leads beyond the independent-particle model. The importance of correlation effects on different capture mechanisms is discussed. 28 refs., 6 figs.

  13. Exposure ages and neutron capture record in lunar samples from Fra Mauro.

    NASA Technical Reports Server (NTRS)

    Lugmair, G. W.; Marti, K.

    1972-01-01

    Cosmic-ray exposure ages of Apollo 14 rocks and rock fragments obtained by the Kr81-Kr83 method range from 27 to 700 m.y. Rock 14321, collected near the Cone crater rim, is one of the many approximately 27 m.y. old ejecta which were reported at the Third Lunar Science Conference. All the other rocks have considerably higher exposure ages. Isotopic anomalies from neutron capture in gadolinium, bromine, and barium are used to obtain information on the lunar neutron spectrum at various depths below the lunar surface. The flux ratio of resonance and slow (less than 0.3 eV) neutrons is found to be nearly constant in the topmost approximately 100 g/sq cm.

  14. A capture-gated neutron spectrometer for characterization of neutron sources and their shields

    NASA Astrophysics Data System (ADS)

    Holm, Philip; Peräjärvi, Kari; Ristkari, Samu; Siiskonen, Teemu; Toivonen, Harri

    2014-07-01

    A portable capture-gated neutron spectrometer was designed and built. The spectrometer consists of a boron-loaded scintillator. Data acquisition is performed in list-mode. 252Cf and AmBe sources and various neutron and gamma shields were used to characterize the response of the device. It is shown that both the unfolded capture-gated neutron spectrum and the singles spectrum up to 5 MeV should be utilized. Source identification is then possible and important information is revealed regarding the surroundings of the source. The detector's discrimination of neutrons from photons is relatively good; specifically, one out of 105 photons is misclassified as a neutron and, more importantly, this misclassification rate can be calculated precisely for different measurement environments and can be taken into account in setting alarm limits for neutron detection. The source and source shield identification capabilities of the detector make it an interesting asset for security applications.

  15. Neutron transfer reactions: Surrogates for neutron capture for basic and applied nuclear science

    SciTech Connect

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, Steven D; Peters, W. A.; Adekola, Aderemi S; Allen, J.; Bardayan, Daniel W; Becker, J.; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Erikson, Luke; Gaddis, A. L.; Harlin, Christopher W; Hatarik, Robert; Howard, Joshua A; Jandel, M.; Johnson, Micah; Kapler, R.; Krolas, W.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Matei, Catalin; Matthews, C.; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Patterson, N. P.; Paulauskas, Stanley; Pelham, T.; Pittman, S. T.; Radford, David C; Rogers, J.; Schmitt, Kyle; Shapira, Dan; ShrinerJr., J. F.; Sissom, D. J.; Smith, Michael Scott; Swan, T. P.; Thomas, J. S.; Vieira, D. J.; Wilhelmy, J. B.; Wilson, Gemma L

    2009-04-01

    Neutron capture reactions on unstable nuclei are important for both basic and applied nuclear science. A program has been developed at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory to study single-neutron transfer (d,p) reactions with rare isotope beams to provide information on neutron-induced reactions on unstable nuclei. Results from (d,p) studies on {sup 130,132}Sn, {sup 134}Te and {sup 75}As are discussed.

  16. 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 compared the RBE characteristics of the MIT Reactor M67 clinical beam, The Brookhaven Medical Research Reactor clinical beam (both of which were used in Phase I/II clinical trials of BNCT) and the MIT LABA BNCS beam. Additional research initiated under this program involved an investigation of the potential of BNCT for the prevention of restenosis and the development of accelerator-based fast neutron brachytherapy. A total of 10 student research theses (2 Undergraduate, 4 Masters, and 4 Doctoral) were completed as part of this research program.

  17. Misassigned neutron resonances of 142Nd and stellar neutron capture cross sections

    NASA Astrophysics Data System (ADS)

    Katabuchi, Tatsuya; Matsuhashi, Taihei; Terada, Kazushi; Igashira, Masayuki; Mizumoto, Motoharu; Hirose, Kentaro; Kimura, Atsushi; Iwamoto, Nobuyuki; Hara, Kaoru Y.; Harada, Hideo; Hori, Jun-ichi; Kamiyama, Takashi; Kino, Koichi; Kitatani, Fumito; Kiyanagi, Yoshiaki; Nakamura, Shoji; Toh, Yosuke

    2015-03-01

    Time-of-flight spectra of the neutron capture events of 142Nd were measured using a spallation neutron source at the Japan Proton Accelerator Research Complex. The first six resonances of 142Nd reported in a previous work were not observed. The experimental results and cross-search of resonance energies in nuclear data libraries suggested that resonances of the impurity nuclide 141Pr have been mistakenly assigned as 142Nd in the previous experiment. To investigate the impact of the nonexistence of the resonances on the s -process nucleosynthesis model, the Maxwellian averaged neutron capture cross sections with and without the misassigned resonances were compared.

  18. How Accurately Can We Calculate Neutrons Slowing Down In Water ?

    SciTech Connect

    Cullen, D E; Blomquist, R; Greene, M; Lent, E; MacFarlane, R; McKinley, S; Plechaty, E; Sublet, J C

    2006-03-30

    We have compared the results produced by a variety of currently available Monte Carlo neutron transport codes for the relatively simple problem of a fast source of neutrons slowing down and thermalizing in water. Initial comparisons showed rather large differences in the calculated flux; up to 80% differences. By working together we iterated to improve the results by: (1) insuring that all codes were using the same data, (2) improving the models used by the codes, and (3) correcting errors in the codes; no code is perfect. Even after a number of iterations we still found differences, demonstrating that our Monte Carlo and supporting codes are far from perfect; in particularly we found that the often overlooked nuclear data processing codes can be the weakest link in our systems of codes. The results presented here represent the today's state-of-the-art, in the sense that all of the Monte Carlo codes are modern, widely available and used codes. They all use the most up-to-date nuclear data, and the results are very recent, weeks or at most a few months old; these are the results that current users of these codes should expect to obtain from them. As such, the accuracy and limitations of the codes presented here should serve as guidelines to code users in interpreting their results for similar problems. We avoid crystal ball gazing, in the sense that we limit the scope of this report to what is available to code users today, and we avoid predicting future improvements that may or may not actual come to pass. An exception that we make is in presenting results for an improved thermal scattering model currently being testing using advanced versions of NJOY and MCNP that are not currently available to users, but are planned for release in the not too distant future. The other exception is to show comparisons between experimentally measured water cross sections and preliminary ENDF/B-VII thermal scattering law, S({alpha},{beta}) data; although these data are strictly preliminary they are currently available and undergoing testing and these results were judged to be within the scope of this report.

  19. Review of Livermore-Led Neutron Capture Studies Using DANCE

    SciTech Connect

    Parker, W; Sheets, S; Agvaanluvsan, U; Becker, J; Becvar, F; Bredeweg, T; Clement, R; Couture, A; Esch, E; Haight, R; Jandel, M; Krticka, M; Mitchell, G; Macri, R; O'Donnell, J; Reifarth, R; Rundberg, R; Schwantes, J; Ullmann, J; Vieira, D; Wouters, J; Wilk, P

    2007-05-11

    We have made neutron capture cross-section measurements using the white neutron source at the Los Alamos Science Center, the DANCE detector array (Detector for Advanced Neutron Capture Experiments) and targets important for basic science and stockpile stewardship. In this paper, we review results from (n,{gamma}) reactions on {sup 94,95}Mo, {sup 152,154,157,160,nat}Gd, {sup 151,153}Eu and {sup 242m}Am for neutron energies from < 1eV up to {approx} 20 keV. We measured details of the {gamma}-ray cascade following neutron capture, for comparison with results of statistical model simulations. We determined the neutron energy dependent (n,{gamma}) cross section and gained information about statistical decay properties, including the nuclear level density and the photon strength function. Because of the high granularity of the detector array, it is possible to look at gamma cascades with a specified number of transitions (a specific multiplicity). We simulated {gamma}-ray cascades using a combination of the DICEBOX/GEANT computer codes. In the case of the deformed nuclei, we found evidence of a scissors-mode resonance. For the Eu, we also determined the (n,{gamma}) cross sections. For the {sup 94,95}Mo, we focused on the spin and parity assignments of the resonances and the determination of the photon strength functions for the compound nuclei {sup 95,96}Mo. Future plans include measurements on actinide targets; our immediate interest is in {sup 242m}Am.

  20. Proposed experiment to measure {gamma}-rays from the thermal neutron capture of gadolinium

    SciTech Connect

    Yano, Takatomi; Ou, I.; Izumi, T.; Yamaguchi, R.; Mori, T.; Sakuda, M.

    2012-11-12

    Gadolinium-157 ({sup 157}Gd) has the largest thermal neutron capture cross section among any stable nuclei. The thermal neutron capture yields {gamma}-ray cascade with total energy of about 8 MeV. Because of these characteristics, Gd is applied for the recent neutrino detectors. Here, we propose an experiment to measure the multiplicity and the angular correlation of {gamma}-rays from the Gd neutron capture. With these information, we expect the improved identification of the Gd neutron capture.

  1. Systematic Measurements of keV-NEUTRON Capture Cross Sections and Capture Gamma-Ray Spectra of pd Isotopes

    NASA Astrophysics Data System (ADS)

    Terada, K.; Igashira, M.; Matsuhashi, T.; Katabuchi, T.; Anh, T. T.

    2013-03-01

    The capture cross sections and capture γ-ray spectra of 104,105Pd were measured in the neutron energy region of 15-100 keV as a part of systematic series of measurements. A neutron time-of-flight method was adopted, using a ns pulsed neutron source via the 7Li(p, n)7Be reaction. The capture γ-rays from the samples were measured with an anti-Compton NaI(Tl) spectrometer. The capture yields were obtained by applying a pulse-height weighting technique to the net capture γ-ray pulse-height spectra. The capture cross sections of 104,105Pd were derived with errors less than 5%, using the standard capture cross sections of 197Au. The capture γ-ray spectra of 104,105Pd were also derived by un-folding the respective observed capture γ-ray pulse-height spectra.

  2. Neutron radiative capture methods for surface elemental analysis

    USGS Publications Warehouse

    Trombka, J.I.; Senftle, F.; Schmadebeck, R.

    1970-01-01

    Both an accelerator and a 252Cf neutron source have been used to induce characteristic gamma radiation from extended soil samples. To demonstrate the method, measurements of the neutron-induced radiative capture and activation gamma rays have been made with both Ge(Li) and NaI(Tl) detectors, Because of the possible application to space flight geochemical analysis, it is believed that NaI(Tl) detectors must be used. Analytical procedures have been developed to obtain both qualitative and semiquantitative results from an interpretation of the measured NaI(Tl) pulse-height spectrum. Experiment results and the analytic procedure are presented. ?? 1970.

  3. Research in Boron Neutron Capture Therapy at MIT LABA

    SciTech Connect

    Yanch, J.C.; Shefer, R.E.; Klinkowstein, R.E.; Howard, W.B.; Song, H.; Blackburn, B.; Binello, E.

    1997-02-01

    A 4.1 MeV tandem electrostatic accelerator designed for research into Boron Neutron Capture Therapy (BNCT) has recently been installed in the MIT Laboratory for Accelerator Beam Applications (LABA). This accelerator uses a very high current switch mode high voltage power supply in conjunction with a multi-cusp negative ion source to supply the multimilliampere current required for clinical BNCT applications. A number of individual research projects aimed at evaluating the potential of this accelerator design as a hospital-based neutron source for radiation therapy of both tumors and rheumatoid arthritis are described here. {copyright} {ital 1997 American Institute of Physics.}

  4. Research in Boron Neutron Capture Therapy at MIT LABA

    NASA Astrophysics Data System (ADS)

    Yanch, J. C.; Shefer, R. E.; Klinkowstein, R. E.; Howard, W. B.; Song, H.; Blackburn, B.; Binello, E.

    1997-02-01

    A 4.1 MeV tandem electrostatic accelerator designed for research into Boron Neutron Capture Therapy (BNCT) has recently been installed in the MIT Laboratory for Accelerator Beam Applications (LABA). This accelerator uses a very high current switch mode high voltage power supply in conjunction with a multi-cusp negative ion source to supply the multimilliampere current required for clinical BNCT applications. A number of individual research projects aimed at evaluating the potential of this accelerator design as a hospital-based neutron source for radiation therapy of both tumors and rheumatoid arthritis are described here.

  5. Zn-71 levels populated in neutron-capture-gamma reactions

    NASA Astrophysics Data System (ADS)

    Huchison, Andrew; Harker, Jessica; Walters, William B.; Waite, Mark; Paul, Rick

    2015-04-01

    The level structure of 71 Zn was studied via the capture-gamma reaction on a highly-enriched 70 Zn target at the NIST Center for Neutron Research NG-7 beam line. The neutron separation energy was determined to be 5832.5(5) keV. Low-spin levels populated in this reaction will be presented, compared with data from other measurements, and discussed. This material is based on work supported by the US Department of Energy (DOE), Office of Science, Office of Nuclear Physics, under Grant No. DE-FG02-94ER40834.

  6. Design of low-energy neutron beams for boron neutron capture synovectomy

    NASA Astrophysics Data System (ADS)

    Yanch, Jacquelyn C.; Shefer, Ruth E.; Binello, E.

    1997-02-01

    A novel application of the 10B(n, (alpha) )7Li nuclear reaction for the treatment of rheumatoid arthritis is under development. this application, called Boron Neutron Capture Synovectomy (BNCS), is briefly described here and the differences between BNCS and Boron Neutron Capture Therapy (BNCT) are discussed in detail. These differences lead to substantially altered demands on neutron beam design for each therapy application. In this paper the considerations for neutron beam design for the treatment of arthritic joints via BNCS are discussed, and comparisons with the design requirements for BNCT are made. This is followed by a description of potential moderator/reflector assemblies that are calculated to produce intense, high- quality neutron beams based on the 7Li(p,n) accelerator- based reactions. Total therapy time and therapeutic ratios are given as a function of both moderator length and boron concentration. Finally, a means of carrying out multi- directional irradiations of arthritic joints is proposed.

  7. Improved performance in synthetic diamond neutron detectors: Application to boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Almaviva, S.; Marinelli, Marco; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.

    2010-01-01

    An improved thermal and fast neutrons detector is obtained, modifying a recently proposed multilayered homoepitaxial Chemical Vapor Deposition (CVD) diamond detector (M. Marinelli, et al., Appl. Phys. Lett. 89 (2006) 143509), where a 6LiF layer deposited on the sensing layer was used to convert thermal neutrons into charged particles. By sandwiching this layer between two CVD diamond detectors connected in parallel, a better signal-to-background separation is achieved. This allows to use 10B as converting element, so to realize a detector suitable for Boron Neutron Capture Therapy dosimetry. Also, the doubled detector volume enhances the sensitivity to fast neutrons.

  8. Neutron Capture and Fission Measurements on Actinides at DANCE

    NASA Astrophysics Data System (ADS)

    Chyzh, Andrii; Wu, Ching-Yen; Kwan, Elaine; Henderson, Rodger; Gostic, Julie; Ullmann, John; Jandel, Marian; Bredeweg, Todd; Couture, Aaron; Lee, Hye Young; Haight, Robert; O'Donnell, John

    2011-10-01

    Neutron capture and fission measurements on actinides are important in nuclear engineering and physics. DANCE (Detector for Advanced Neutron Capture Measurement build at LANL) together with PPAC (avalanche technique based fission tagging detector designed and fabricated at LLNL) were used to measure the prompt γ-ray energy and multiplicity distributions in the spontaneous fission of 252Cf. These measured spectra together with the unfolded ones will be presented. The unfolding technique will be described. In addition the 238Pu(n , γ) cross section will be presented, which was measured using DANCE alone and also is the first such measurement in a laboratory environment. This work was performed under the auspices of the US Department of Energy by Los Alamos National Laboratory under Contract DE-AC52-06NA25396 and Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. Thermal Neutron Capture Cross Sections Of The Palladium Isotopes

    SciTech Connect

    Firestone, R. B.; Krtiaka, M.; McNabb, D. P.; Sleaford, B.; Agvaanluvsan, U.; Belgya, T.; Revay, Zs.

    2006-03-13

    We have measured precise thermal neutron capture {gamma}-ray cross sections cry for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature and have been evaluated into the Evaluated Gamma-ray Activation File (EGAF). Total radiative neutron capture cross-sections {sigma}{gamma} can be deduced from the sum of transition cross sections feeding the ground state of each isotope if the decay scheme is complete. The Palladium isotope decay schemes are incomplete, although transitions deexciting low-lying levels are known for each isotope. We have performed Monte Carlo simulations of the Palladium thermal neutron capture deexcitation schemes using the computer code DICEBOX. This program generates level schemes where levels below a critical energy Ecrit are taken from experiment, and those above Ecrit are calculated by a random discretization of an a priori known level density formula {rho}(E,J{pi}). Level de-excitation branching intensities are taken from experiment for levels below Ecrit the capture state, or calculated for levels above Ecrit assuming an a priori photon strength function and applying allowed selection rules and a Porter-Thomas distribution of widths. The advantage of this method is that calculational uncertainties can be investigated systematically. Calculated feeding to levels below Ecrit can be normalized to the measured cross section deexciting those levels to determine the total radiative neutron cross-section {sigma}{gamma}. In this paper we report the cross section measurements {sigma}{gamma}[102Pd(n,{gamma})]=0.9{+-}0.3 b, {sigma}{gamma}[104Pd(n,{gamma})=0.61{+-}0.11 b, {sigma}{gamma}[105Pd(n,{gamma})]=2.1.1{+-}1.5 b, {sigma}{gamma}[106Pd(n,{gamma})]=0.36{+-}0.05 b, {sigma}{gamma}[108Pd(n,{gamma})(0)]=7.6{+-}0.6 b, {sigma}{gamma}[108Pd(n,{gamma})(189)]=0.185{+-}0.011 b, and {sigma}{gamma}[110Pd(n,{gamma})]=0.10{+-}0.03 b. We have also determined from our statistical calculations that the neutron capture states in 107Pd are best described as 2+[59(4)%]+3+[41(4)%]. Agreement with literature values was excellent in most cases. We found significant discrepancies between our results for 102Pd and 110Pd and earlier values that could be resolved by re-evaluation of the earlier results.

  10. Thermal Neutron Capture Cross Sections Of The Palladium Isotopes

    NASA Astrophysics Data System (ADS)

    Firestone, R. B.; Krtika, M.; McNabb, D. P.; Sleaford, B.; Agvaanluvsan, U.; Belgya, T.; Rvay, Zs.

    2006-03-01

    We have measured precise thermal neutron capture ?-ray cross sections cry for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature and have been evaluated into the Evaluated Gamma-ray Activation File (EGAF). Total radiative neutron capture cross-sections ?? can be deduced from the sum of transition cross sections feeding the ground state of each isotope if the decay scheme is complete. The Palladium isotope decay schemes are incomplete, although transitions deexciting low-lying levels are known for each isotope. We have performed Monte Carlo simulations of the Palladium thermal neutron capture deexcitation schemes using the computer code DICEBOX. This program generates level schemes where levels below a critical energy Ecrit are taken from experiment, and those above Ecrit are calculated by a random discretization of an a priori known level density formula ?(E,J?). Level de-excitation branching intensities are taken from experiment for levels below Ecrit the capture state, or calculated for levels above Ecrit assuming an a priori photon strength function and applying allowed selection rules and a Porter-Thomas distribution of widths. The advantage of this method is that calculational uncertainties can be investigated systematically. Calculated feeding to levels below Ecrit can be normalized to the measured cross section deexciting those levels to determine the total radiative neutron cross-section ??. In this paper we report the cross section measurements ??[102Pd(n,?)]=0.90.3 b, ??[104Pd(n,?)=0.610.11 b, ??[105Pd(n,?)]=2.1.11.5 b, ??[106Pd(n,?)]=0.360.05 b, ??[108Pd(n,?)(0)]=7.60.6 b, ??[108Pd(n,?)(189)]=0.1850.011 b, and ??[110Pd(n,?)]=0.100.03 b. We have also determined from our statistical calculations that the neutron capture states in 107Pd are best described as 2+[59(4)%]+3+[41(4)%]. Agreement with literature values was excellent in most cases. We found significant discrepancies between our results for 102Pd and 110Pd and earlier values that could be resolved by re-evaluation of the earlier results.

  11. Abundance Patterns of Neutron-Capture Elements in the Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Ritchey, Adam M.; Federman, S. R.; Lambert, D. L.

    2012-01-01

    We present the results of an archival survey of neutron-capture elements in diffuse interstellar clouds from HST/STIS observations of over 50 Galactic sight lines. Existing measurements of the interstellar abundances of Kr, Rb, Cd, and Sn have indicated deficiencies in our understanding of the production of elements beyond the iron peak via slow and rapid neutron-capture processes. The elements Kr and Rb, which are primarily synthesized by massive stars through the weak s-process and the r-process, are found to be underabundant in interstellar gas compared to expectations based on current knowledge of dust depletion. At the same time, Cd and Sn, which are produced in larger part by the main s-process in low-mass AGB stars, exhibit less depletion than expected. By combining new abundance determinations for As, Cd, Sn, and Pb with recent surveys of Ga, Ge, Kr, and Rb, our study seeks to reveal the causes of the inferred deficit in the contribution from massive stars to the abundances of neutron-capture elements in the current epoch. We find that while Ga, Ge, and Pb follow normal depletion patterns, As is significantly overabundant, with an overall depletion level similar to Sn. Yet, unlike Sn, As is almost entirely a product of massive-star nucleosynthesis. The ultimate resolution of these discrepancies will likely involve a deeper understanding of dust grain depletion than presently exists. This research was funded by the Space Telescope Science Institute through grant HST-AR-12123.

  12. Stellar neutron capture cross sections of the Lu isotopes

    SciTech Connect

    Wisshak, K.; Voss, F.; Kaeppeler, F.; Kazakov, L.

    2006-01-15

    The neutron capture cross sections of {sup 175}Lu and {sup 176}Lu have been measured in the energy range 3-225 keV at the Karlsruhe 3.7 MV Van de Graaff accelerator. Neutrons were produced via the {sup 7}Li(p,n){sup 7}Be reaction by bombarding metallic Li targets with a pulsed proton beam, and capture events were registered with the Karlsruhe 4{pi} barium fluoride detector. The cross sections were determined relative to the gold standard using isotopically enriched as well as natural lutetium oxide samples. Overall uncertainties of {approx}1% could be achieved in the final cross section ratios to the gold standard, about a factor of 5 smaller than in previous works. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 8 and 100 keV. These values are systematically larger by {approx}7% than those reported in recent evaluations. These results are of crucial importance for the assessment of the s-process branchings at A 175/176.

  13. Modern alchemy: Fred Hoyle and element building by neutron capture

    NASA Astrophysics Data System (ADS)

    Burbidge, E. Margaret

    Fred Hoyle's fundamental work on building the chemical elements by nuclear processes in stars at various stages in their lives began with the building of elements around iron in the very dense hot interiors of stars. Later, in the paper by Burbidge, Burbidge, Fowler and Hoyle, we four showed that Hoyle's "equilibrium process" is one of eight processes required to make all of the isotopes of all the elements detected in the Sun and stars. Neutron capture reactions, which Fred had not considered in his epochal 1946 paper, but for which experimental data were just becoming available in 1957, are very important, in addition to the energy-generating reactions involving hydrogen, helium, carbon, nitrogen and oxygen, for building all of the elements. They are now providing clues to the late stages of stellar evolution and the earliest history of our Galaxy. I describe here our earliest observational work on neutron capture processes in evolved stars, some new work on stars showing the results of the neutron capture reactions, and data relating to processes ending in the production of lead, and I discuss where this fits into the history of stars in our own Galaxy.

  14. Clinical treatment planning of subjects undergoing boron neutron capture therapy

    SciTech Connect

    Riley, K.; Zamenhof, R.; Solares, G.

    1996-12-31

    The sequence of treatment planning operations for clinical boron neutron capture therapy (BNCT) in the New England Deaconess Hospital-Massachusetts Institute of Technology (MIT) BNCT program consists of multiple computational and experimental steps. The course of action for each subject has been categorized into several steps, each of which is introduced and summarized in this paper. Those steps are: 1. Calibration of epithermal neutron beam via in-phantom dose measurements and calibration of beam monitoring system; 2. Administration of test dose of BPA-f (boron compound) to subject; 3. Analyses of blood and tissue samples for boron content; 4. CT scanning of subject; 5. Calculation of treatment plan; 6. Irradiation of subject in the epithermal neutron beam at the MIT research reactor.

  15. Improved neutron capture cross section of Pu239

    NASA Astrophysics Data System (ADS)

    Mosby, S.; Bredeweg, T. A.; Chyzh, A.; Couture, A.; Henderson, R.; Jandel, M.; Kwan, E.; O'Donnell, J. M.; Ullmann, J.; Wu, C. Y.

    2014-03-01

    The 239Pu(n ,?) cross section has been measured over the energy range 10 eV to 1 keV using the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center as part of a campaign to produce precision (n ,?) measurements on 239Pu. Fission coincidences were measured with a parallel-plate avalanche counter and used to measure the prompt fission ?-ray spectrum in this region to accurately characterize background. The resulting (n ,?) cross section is generally in agreement with current evaluations. The experimental method utilizes much more detailed information than past measurements on 239Pu and can be used to extend the measurement to higher incident neutron energies.

  16. High-current electrostatic accelerator for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Shefer, Ruth E.; Klinkowstein, Robert E.; Yanch, Jacquelyn C.

    1997-02-01

    The use of boron neutron capture therapy in clinical treatment will require the development of intense neutron sources suitable for operation in a hospital environment. Low-energy accelerator-based neutron sources have the potential for meeting the requirements for a clinical BNCT facility. This paper describes the design, installation, and initial operation of the first high current tandem accelerator for this application. The accelerator utilizes a highly power efficient switch-mode high voltage generator to deliver proton beams with energies of up to 4.1 MeV. The use of a multi-cusp high current negative ion source in combination with magnetically suppressed accelerating tubes allows the acceleration of proton beam currents up to 4 mA. The design principles and operation of the accelerator are described.

  17. Thermal neutron capture cross sections of the potassium isotopes

    NASA Astrophysics Data System (ADS)

    Firestone, R. B.; Krti?ka, M.; Rvay, Zs.; Szentmiklosi, L.; Belgya, T.

    2013-02-01

    Precise thermal neutron capture ?-ray cross sections ?? for 39,40,41K were measured on a natural potassium target with the guided neutron beam at the Budapest Reactor. The cross sections were internally standardized using a stoichiometric KCl target with well-known 35Cl(n,?) ?-ray cross sections [Rvay and Molnr, Radiochimica ActaRAACAP0033-823010.1524/ract.91.6.361.20027 91, 361 (2003); Molnr, Rvay, and Belgya, Nucl. Instrum. Meth. Phys. Res. BNIMBEU0168-583X10.1016/S0168-583X(03)01529-5 213, 32 (2004)]. These data were combined with ?-ray intensities from von Egidy [von Egidy, Daniel, Hungerford, Schmidt, Lieb, Krusche, Kerr, Barreau, Borner, Brissot , J. Phys. G. Nucl. Phys.JPHGBM0305-461610.1088/0305-4616/10/2/013 10, 221 (1984)] and Krusche [Krusche, Lieb, Ziegler, Daniel, von Egidy, Rascher, Barreau, Borner, and Warner, Nucl. Phys. ANUPABL0375-947410.1016/0375-9474(84)90506-2 417, 231 (1984); Krusche, Winter, Lieb, Hungerford, Schmidt, von Egidy, Scheerer, Kerr, and Borner, Nucl. Phys. ANUPABL0375-947410.1016/0375-9474(85)90429-4 439, 219 (1985)] to generate nearly complete capture ?-ray level schemes. Total radiative neutron cross sections were deduced from the total ?-ray cross section feeding the ground state, ?0=???(GS) after correction for unobserved statistical ?-ray feeding from levels near the neutron capture energy. The corrections were performed with Monte Carlo simulations of the potassium thermal neutron capture decay schemes using the computer code dicebox where the simulated populations of low-lying levels are normalized to the measured cross section depopulating those levels. Comparisons of the simulated and experimental level feeding intensities have led to proposed new spins and parities for selected levels in the potassium isotopes where direct reactions are not a significant contribution. We determined the total radiative neutron cross sections ?0(39K)=2.280.04 b, ?0(40K)=907 b, and ?0(41K)=1.620.03 b from the prompt ?-ray data and the ?-ray transition probability P?(1524.66)=0.164(4) in the ?- decay of 42K in a low-background counting experiment.

  18. Development of a boron neutron capture enhanced fast neutron therapy beam

    NASA Astrophysics Data System (ADS)

    Sweezy, Jeremy Ed

    The combination of fast neutron therapy and boron neutron capture therapy is currently under investigation at several fast neutron therapy centers worldwide. This treatment method, termed boron neutron capture enhanced fast neutron therapy (BNCEFNT) utilizes a boron containing drug to selectively increase the dose to the target tumor. BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiforme. A neutron therapy beam for boron neutron capture enhanced fast neutron therapy has been developed for the existing Fermilab Neutron Therapy Facility. This beam produces a significant dose enhancement due to the boron neutron capture reaction. The beam was developed by designing a filter and collimator system using the Monte Carlo radiation transport code, MCNPX. The MCNPX code was benchmarked against depth-dose measurements of the standard treatment beam. The new BNCEFNT beam is filtered with 18.3-cm of low carbon steel and is collimated with steel. Measurements of the dose enhancement of the new BNCEFNT beam were performed with paired tissue equivalent ion chambers. One of the ion chambers has boron incorporated in the wall of the chamber to measure the dose due to boron neutron capture. The measured boron dose enhancement of the BNCEFNT beam is (16.3 +/- 2.6)% per 100-ppm 10B for a 20-cm diameter beam and (10.0 +/- 1.6)% per 100-ppm 10B for a 10-cm diameter beam. The dose rate of the new beam is reduced to 4.4% of the dose rate of the standard treatment beam. A conceptual design that overcomes the reduced dose rate is also presented. This design uses a tungsten collimator placed near the patient, with a 1.5-cm tungsten filter just upstream of the collimator. Using graphite moderation of neutrons around the patient a percent dose enhancement of 15% can be attained with good collimation, for field sizes as small as 5 x 5 cm2 , and without a reduction in dose rate.

  19. Neutron capture and (n,2n) measurements on 241Am

    SciTech Connect

    Vieira, D; Jandel, M; Bredeweg, T; Bond, E; Clement, R; Couture, A; Haight, R; O'Donnell, J; Reifarth, R; Ullmann, J; Wilhelmy, J; Wouters, J; Tonchev, A; Hutcheson, A; Angell, C; Crowell, A; Fallin, B; Hammond, S; Howell, C; Karowowski, H; Kelley, J; Pedroni, R; Tornow, W; Macri, R; Agvaanluvsan, U; Becker, J; Dashdorj, D; Stoyer, M; Wu, C

    2007-07-18

    We report on a set of neutron-induced reaction measurements on {sup 241}Am which are important for nuclear forensics and advanced nuclear reactor design. Neutron capture measurements have been performed on the DANCE detector array at the Los Alamos Neutron Scattering CEnter (LANSCE). In general, good agreement is found with the most recent data evaluations up to an incident neutron energy of {approx} 300 keV where background limits the measurement. Using mono-energetic neutrons produced in the {sup 2}H(d,n){sup 3}He reaction at Triangle University Nuclear Laboratory (TUNL), we have measured the {sup 241}Am(n,2n) excitation function from threshold (6.7 MeV) to 14.5 MeV using the activation method. Good agreement is found with previous measurements, with the exception of the three data points reported by Perdikakis et al. around 11 MeV, where we obtain a much lower cross section that is more consistent with theoretical estimates.

  20. Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments

    SciTech Connect

    Trbovich, Michael J.; Barry, Devin P.; Burke, John A.; Drindak, Noel J.; Leinweber, Greg; Ballad, Robert V.; Slovacek, Rudy E.; Danon, Yaron; Block, Robert C.

    2005-05-24

    The focus of this work is to determine resonance parameters for stable hafnium isotopes in the 0.005-200 eV region, with special emphasis on the overlapping 176Hf and 178Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions.Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. 6Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen-section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically enriched liquid samples. The liquid samples were designed to provide information on the 176Hf and 178Hf contributions to the 8-eV doublet without saturation.Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. Resonance integrals were calculated along with errors for each hafnium isotope using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than previously published values; however the calculated elemental hafnium resonance integral changed very little.

  1. Systematic Measurement of keV-Neutron Capture Cross Sections and Capture Gamma-Ray Spectra of Zr Isotopes

    SciTech Connect

    Ohgama, Kazuya; Igashira, Masayuki; Ohsaki, Toshiro

    2005-05-24

    The capture cross sections of 92Zr were measured in the incident neutron energy region from 15 to 90 keV and at 550 keV. A neutron time-of-flight method was adopted with a ns-pulsed neutron source by the 7Li(p,n)7Be reaction and with a large anti-Compton NaI(Tl) spectrometer. A pulse-height weighting technique was applied to observed capture gamma-ray pulse-height spectra to derive capture yields. Using the standard capture cross sections of 197Au in ENDF/B-VI, the capture cross sections of 92Zr were obtained with the errors from 7% to 11%. The present results were compared with previous measurements and the evaluations of JENDL-3.3 and ENDF/B-VI. The capture gamma-ray spectra of 92Zr were derived by unfolding observed capture gamma-ray pulse-height spectra.

  2. Measurements of keV-neutron Capture Cross Sections and Capture Gamma-ray Spectra of Pd Isotopes

    NASA Astrophysics Data System (ADS)

    Terada, K.; Matsuhashi, T.; Hales, B.; Katabuchi, T.; Igashira, M.

    2014-05-01

    The capture cross sections and capture gamma-ray spectra of 104,105,106,108,110Pd were measured in the neutron energy region from 15 to 100 keV. A neutron time-of-flight method was utilized by means of an anti-Compton NaI(Tl) spectrometer and a 1.5 nsec pulsed neutron source via the 7Li(p,n)7Be reaction. The capture yields were obtained by applying a pulse-height weighting technique to the net gamma-ray pulse-height spectra. The capture cross sections of 104,105,106,108,110Pd were determined with uncertainties of less than 6%, using the standard capture cross sections of 197Au. The capture gamma-ray spectra of 104,105,106,108,110Pd were also derived by unfolding the respective observed capture gamma-ray pulse-height spectra.

  3. Highlights from 35 Years of Fission Research with Slow Neutrons at the Ill

    NASA Astrophysics Data System (ADS)

    Gönnenwein, F.

    2014-09-01

    The Institut Laue-Langevin in Grenoble/France was founded in 1967 as a center for research with neutrons. The neutron source is a High Flux Reactor. Studies of slow neutron induced fission started in 1975. Since that time some 500 experiments with fission fragments were conducted up to 2012. Out of the many different topics having been tackled only two highlights are selected for the present report: even-odd staggering of proton and neutron numbers of fission fragments in cold fission, and studies of fission with cold polarized neutrons.

  4. Nuclear data sensitivities and the rapid neutron capture process

    NASA Astrophysics Data System (ADS)

    Mumpower, Matthew

    2015-04-01

    Simulations of the rapid neutron capture or r process of nucleosynthesis require the input of thousands of pieces of nuclear data for which no experimental information is available. These uncertain nuclear quantities are coupled, for instance, nuclear masses effect r-process abundances by entering into calculations of Q-values, neutron capture rates, photo-dissociation rates, ?-decay rates and the probability to emit neutrons. We report on our recent studies of nuclear data sensitivities in the r process. These studies take into account the propagation of uncertainties to properly identify individual nuclei that influence r-process abundances over a range of nuclear models and astrophysical conditions. We additionally explore the impact of uncertainties in nuclear data on the r process by performing global Monte Carlo simulations. We conclude that the reduction of nuclear data uncertainties either by new measurements or by improved nuclear models will allow for more robust r-process predictions. This work was supported by the Joint Institute for Nuclear Astrophysics Grant Number PHY0822648.

  5. 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.

  6. Isodose Curves and Treatment Planning for Boron Neutron Capture Therapy.

    NASA Astrophysics Data System (ADS)

    Liu, Hungyuan B.

    The development of Boron Neutron Capture Therapy (BNCT) has been progressing in both ^{10 }B compound development and testing and neutron beam delivery. Animal tests are now in progress with several ^{10}B compounds and once the results of these animal tests are promising, patient trials can be initiated. The objective of this study is to create a treatment planning method based on the dose calculations by a Monte Carlo code of a mixed radiation field to provide linkage between phantom dosimetry and patient irradiation. The research started with an overall review of the development of BNCT. Three epithermal neutron facilities are described, including the operating Brookhaven Medical Research Reactor (BMRR) beam, the designed Missouri University Research Reactor (MURR) beam, and a designed accelerator based neutron source. The flux and dose distributions in a head model have been calculated for irradiation by these neutron beams. Different beam parameters were inter -compared for effectiveness. Dosimetric measurements in an elliptical lucite phantom and a cylindrical water phantom were made and compared to the MCNP calculations for irradiation by the BMRR beam. Repeated measurements were made and show consistent. To improve the statistical results calculated by MCNP, a neutron source plane was designed to start neutrons at the BMRR irradiation port. The source plane was used with the phantoms for dosimetric calculations. After being verified by different phantom dosimetry and in-air flux measurements at the irradiation port, the source plane was used to calculate the flux and dose distributions in the head model. A treatment planning program was created for use on a PC which uses the MCNP calculated results as input. This program calculates the thermal neutron flux and dose distributions of each component of radiation in the central coronal section of the head model for irradiation by a neutron beam. Different combinations of head orientations and irradiation weighting factors can be combined to predict a better dose distribution. Specific input data files were created for the BMRR beam and several examples have been examined with the program.

  7. The heavy element yields of neutron capture nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Cameron, A. G. W.

    1982-01-01

    Consideration of the contribution made to the abundances of the heavy element isotopes by the S- and R-processes of nucleosynthesis has led to the determination that the previous assumption concerning the exclusive alignment of isobars to one or the other of these processes is probably in error. If the relatively small odd and even mass number abundance fluctuations characterizing R-process abundances are always the case, as assumed by this study, S-process contributions to the abundances of R-process isobars are substantial, consistent with transient flashing episodes in the S-process neutron production processes. A smooth and monotonically-decreasing curve of the abundance of the S-process yields times the neutron capture cross-section versus mass number is therefore the primary tool for the separation of the abundances due to the two processes.

  8. Scissors Mode of 162 Dy Studied from Resonance Neutron Capture

    DOE PAGESBeta

    Baramsai, B.; Bečvář, F.; Bredeweg, T. A.; Haight, R. C.; Jandel, M.; Kroll, J.; Krtička, M.; Mitchell, G. E.; O’Donnell, J. M.; Rundberg, R. S.; et al

    2015-05-28

    Multi-step cascade γ-ray spectra from the neutron capture at isolated resonances of 161Dy nucleus were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The objectives of this experiment were to confirm and possibly extend the spin assignment of s-wave neutron resonances and get new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. The preliminary results show that the scissors mode plays a significant role in all transitions between accessible states of the studied nucleus. The photon strength functions describing well our data are compared to results from 3He-induced reactions,more » (n,γ) experiments on Gd isotopes, and (γ,γ’) reactions.« less

  9. Thermal neutron capture cross section of {sup 74}Ge

    SciTech Connect

    Meierhofer, G.; Grabmayr, P.; Jochum, J.; Kudejova, P.; Canella, L.; Jolie, J.

    2010-02-15

    The thermal neutron capture cross sections of the {sup 74}Ge(n,{gamma}){sup 75}Ge and the {sup 74}Ge(n,{gamma}){sup 75m}Ge reactions have been measured by the activation method. Cold neutrons were used to activate GeO{sub 2} targets depleted in {sup 76}Ge. From the decay spectra of {sup 75}Ge measured with high-purity germanium detectors, the cross sections relative to {sup 197}Au were derived. For the {sup 74}Ge(n,{gamma}){sup 75m}Ge reaction, a value of (130.5+-5.6) mb was found and the ground state was populated with a cross section of (497+-52) mb.

  10. Scissors Mode of 162Dy Studied from Resonance Neutron Capture

    NASA Astrophysics Data System (ADS)

    Baramsai, B.; Bečvář, F.; Bredeweg, T. A.; Haight, R. C.; Jandel, M.; Kroll, J.; Krtička, M.; Mitchell, G. E.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Wilhelmy, J. B.

    2015-05-01

    Multi-step cascade γ-ray spectra from the neutron capture at isolated resonances of 161Dy nucleus were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The objectives of this experiment were to confirm and possibly extend the spin assignment of s-wave neutron resonances and get new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. The preliminary results show that the scissors mode plays a significant role in all transitions between accessible states of the studied nucleus. The photon strength functions describing well our data are compared to results from 3He-induced reactions, (n,γ) experiments on Gd isotopes, and (γ,γ') reactions.

  11. Boron neutron capture enhancement of 252Cf brachytherapy.

    PubMed

    Beach, J L; Schroy, C B; Ashtari, M; Harris, M R; Maruyama, Y

    1990-06-01

    Dosimetric and radiobiological studies were undertaken to investigate the potential enhancement in dose, dose distribution and cell killing effectiveness of 252Cf brachytherapy achievable when boron-10 enriched compounds are incorporated into simulated 252Cf brain implants. Thermal neutron distributions in a human head phantom containing a 252Cf source were measured by gold foil activation and calculated using a 1-dimensional transport code. This information was then used to modify measured event size distributions for 252Cf neutrons to determine the corresponding increase in dose and dose equivalent throughout the phantom. The addition of subtoxic levels of boron-10 to a typical 252Cf implant was found to significantly enhance both the absorbed dose and the high LET event frequency at distances of 3 to 5 cm from individual sources. Some unexpected geometric considerations are discussed. Reduced survival of cultured Chinese hamster cells correlated with the predicted increase in absorbed dose from the capture events with a concentration of about 60 micrograms 10B per ml in the culture medium. It was found that boron increased alpha (the "single-hit" parameter of the linear quadratic survival model) by 32% and decreased beta (the "double-hit" parameter) by 8%. The alpha/beta ratio increased to 4.34 Gy in the presence of boron, from 3.03 Gy in its absence. This translated to an 8% reduction in californium dose needed to effect 10% cell survival. It is concluded that there is a sufficiently high thermal neutron fluence present during californium brachytherapy for boron neutron capture dose augmentation to be feasible. PMID:2370192

  12. Is (d,p{gamma}) a surrogate for neutron capture?

    SciTech Connect

    Hatarik, R.; Cizewski, J. A.; O'Malley, P. D.; Bernstein, L. A.; Burke, J. T.; Lesher, S. R.; Gibelin, J. D.; Phair, L. W.; Swan, T.

    2008-04-17

    To benchmark the validity of using the (d,p{gamma}) reaction as a surrogate for (n,{gamma}), the {sup 171,173}Yb(d,p{gamma}) reactions were measured and compared with the neutron capture cross sections measured by Wisshak et al. The (d,p{gamma}) ratios were measured using an 18.5 MeV deuteron beam from the 88-Inch Cyclotron at LBNL. Preliminary results comparing the surrogate ratios with the known (n,{gamma}) cross sections are discussed.

  13. Improved Neutron Capture Gamma-Ray Data and Evaluation

    NASA Astrophysics Data System (ADS)

    Sleaford, B.; Basunia, Shamsuzzoha; Becvar, F.; Belgya, T.; Bernstein, L.; Choi, H.; Escher, J.; Firestone, R.; Genreith, C.; Gunsing, F.; Hurst, A.; Krticka, M.; Revay, Z.; Rossbach, M.; Summers, N.; Szentmiklosi, L.

    2014-09-01

    The neutron-capture reaction is of fundamental use in identifying and analyzing the gamma-ray spectrum from an unknown object as it gives a fingerprint of which isotopes are present. Many isotopes have capture gamma lines from 5-10 MeV potentially making them easier to detect against background lines. There are data gaps in the Evaluated Nuclear Data File (ENDF) libraries used by modeling codes (the actinides have no lines for example) and we are filling these with the Evaluated Gamma-ray Activation File (EGAF), using an IAEA atlas of reactor measured lines and cross sections for over 260 isotopes. For medium to heavy nuclei, the unresolved part of the gamma cascades is not measured and are modeled using the statistical nuclear structure code Dicebox [1,2]. ENDF libraries require cross sections for neutron energies up to 20 MeV and we plan to continue this approach through the resolved resonance region. The neutron-capture reaction is of fundamental use in identifying and analyzing the gamma-ray spectrum from an unknown object as it gives a fingerprint of which isotopes are present. Many isotopes have capture gamma lines from 5-10 MeV potentially making them easier to detect against background lines. There are data gaps in the Evaluated Nuclear Data File (ENDF) libraries used by modeling codes (the actinides have no lines for example) and we are filling these with the Evaluated Gamma-ray Activation File (EGAF), using an IAEA atlas of reactor measured lines and cross sections for over 260 isotopes. For medium to heavy nuclei, the unresolved part of the gamma cascades is not measured and are modeled using the statistical nuclear structure code Dicebox [1,2]. ENDF libraries require cross sections for neutron energies up to 20 MeV and we plan to continue this approach through the resolved resonance region. This work is performed in part under the auspices of the USDoE by LLNL under Contract DE-AC52-07NA27344.

  14. Design of a boron neutron capture enhanced fast neutron therapy assembly

    SciTech Connect

    Wang, Zhonglu

    2006-08-01

    The use of boron neutron capture to boost tumor dose in fast neutron therapy has been investigated at several fast neutron therapy centers worldwide. This treatment is termed boron neutron capture enhanced fast neutron therapy (BNCEFNT). It is a combination of boron neutron capture therapy (BNCT) and fast neutron therapy (FNT). It is believed that BNCEFNT may be useful in the treatment of some radioresistant brain tumors, such as glioblastoma multiform (GBM). A boron neutron capture enhanced fast neutron therapy assembly has been designed for the Fermilab Neutron Therapy Facility (NTF). This assembly uses a tungsten filter and collimator near the patient's head, with a graphite reflector surrounding the head to significantly increase the dose due to boron neutron capture reactions. The assembly was designed using Monte Carlo radiation transport code MCNP version 5 for a standard 20x20 cm{sup 2} treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm{sup 2} collimation was 21.9% per 100-ppm {sup 10}B for a 5.0-cm tungsten filter and 29.8% for a 8.5-cm tungsten filter. The corresponding dose rate for the 5.0-cm and 8.5-cm thick filters were 0.221 and 0.127 Gy/min, respectively; about 48.5% and 27.9% of the dose rate of the standard 10x10 cm{sup 2} fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm{sup 2} collimator. Five 1.0-cm thick 20x20 cm{sup 2} tungsten plates were used to obtain different filter thicknesses and graphite bricks/blocks were used to form a reflector. Measurements of the dose enhancement of the simplified assembly in a water-filled head phantom were performed using a pair of tissue-equivalent ion chambers. One of the ion chambers is loaded with 1000-ppm natural boron (184-ppm {sup 10}B) to measure dose due to boron neutron capture. The measured dose enhancement at 5.0-cm depth in the head phantom for the 5.0-cm thick tungsten filter is (16.6 {+-} 1.8)%, which agrees well with the MCNP simulation of the simplified BNCEFNT assembly, (16.4 {+-} 0.5)%. The error in the calculated dose enhancement only considers the statistical uncertainties. The total dose rate measured at 5.0-cm depth using the non-borated ion chamber is (0.765 {+-} 0.076) Gy/MU, about 61% of the fast neutron standard dose rate (1.255Gy/MU) at 5.0-cm depth for the standard 10x10 cm{sup 2} treatment beam. The increased doses to other organs due to the use of the BNCEFNT assembly were calculated using MCNP5 and a MIRD phantom. The activities of the activation products produced in the BNCEFNT assembly after neutron beam delivery were computed. The photon ambient dose rate due to the radioactive activation products was also estimated.

  15. 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.

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

    DOEpatents

    Yoon, Woo Y. (Idaho Falls, ID); Jones, James L. (Idaho Falls, ID); Nigg, David W. (Idaho Falls, ID); Harker, Yale D. (Idaho Falls, ID)

    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.

  17. Carborane derivative development for boron neutron capture therapy. Final report

    SciTech Connect

    Barnum, Beverly A.; Yan Hao; Moore, Roger; Hawthorne, M. Frederick; Baum, Kurt

    1999-04-01

    Boron Neutron Capture Therapy [BNCT] is a binary method of cancer therapy based on the capture of neutrons by a boron-10 atom [{sup 10}B]. Cytotoxic {sup 7}Li nuclei and {alpha}-particles are emitted, with a range in tissue of 9 and 5 {micro}m, respectively, about one cell diameter. The major obstacle to clinically viable BNCT is the selective localization of 5-30 ppm {sup 10}B in tumor cells required for effective therapy. A promising approach to BNCT is based on hydrophilic boron-rich oligomeric phosphate diesters, or ''trailers'' that have been shown to concentrate selectively in tumor tissue. Examples of these compounds were prepared previously at high cost using an automated DNA synthesizer. Direct synthesis methods are needed for the production of gram-scale quantities for further biological evaluation. The work accomplished as a result of the collaboration between Fluorochem, Inc. and UCLA demonstrates that short oligomers containing at least five carborane units with four phosphodiester linkages can be prepared in substantial quantities. This work was accomplished by the application of standard phosphoramidite coupling chemistry.

  18. Thermal-neutron capture gamma-rays. Volume 1

    SciTech Connect

    Tuli, J.K.

    1997-05-01

    The energy and photon intensity of gamma rays as seen in thermal-neutron capture are presented in ascending order of gamma energy. All those gamma-rays with intensity of {ge} 2% of the strongest transition are included. The two strongest transitions seen for the target nuclide are indicated in each case. Where the target nuclide mass number is indicated as nat the natural target was used. The gamma energies given are in keV. The gamma intensities given are relative to 100 for the strongest transition. All data for A > 44 are taken from Evaluated Nuclear Structure Data File (4/97), a computer file of evaluated nuclear structure data maintained by the National Nuclear Data Center, Brookhaven National Laboratory, on behalf of the Nuclear Structure and Decay and Decay Data network, coordinated by the International Atomic Energy Agency, Vienna. These data are published in Nuclear Data Sheets, Academic Press, San Diego, CA. The data for A {le} 44 is taken from ``Prompt Gamma Rays from Thermal-Neutron Capture,`` M.A. Lone, R.A. Leavitt, D.A. Harrison, Atomic Data and Nuclear Data Tables 26, 511 (1981).

  19. Boron neutron capture therapy for malignant melanoma: An experimental approach

    SciTech Connect

    Larsson, B.S.; Larsson, B.; Roberto, A. )

    1989-07-01

    Previous studies have shown that some thioamides, e.g., thiouracil, are incorporated as false precursors into melanin during its synthesis. If boronated analogs of the thioamides share this property, the melanin of melanotic melanomas offers a possibility for specific tumoural uptake and retention of boron as a basis for neutron capture therapy. We report on the synthesis of boronated 1H-1,2,4-triazole-3-thiol (B-TZT), boronated 5-carboxy-2-thiouracil (B-CTU), and boronated 5-diethylaminomethyl-2-thiouracil (B-DEAMTU) and the localization of these substances in melanotic melanomas transplanted to mice. The distribution in the mice was studied by boron neutron capture radiography. B-TZT and B-CTU showed the highest tumour:normal tissue concentration ratios, with tumour:liver ratios of about 4 and tumour:muscle ratios of about 14; B-DEAMTU showed corresponding ratios of 1.4 and 5, respectively. The absolute concentration of boron in the tumours, however, was more than three times higher in the mice injected with B-TZT, compared with B-CTU. The results suggest that B-TZT may be the most promising compound of the three tested with regard to possible therapy of melanotic melanomas.

  20. Neutron-capture processes in the early Galaxy

    NASA Astrophysics Data System (ADS)

    Aoki, Wako

    Many observational studies of metal-poor stars that exhibit large excesses of r-process elements have been made in the past decade, and have provided useful constraints on modeling this pro- cess. Recent abundance studies have revealed the existence of extremely metal-poor stars that have large enhancements exclusively of the light neutron-capture elements, indicating that a nu- cleosynthesis process that efficiently yields these elements operated in the very early Galaxy. We review these recent measurements of light neutron-capture elements in the field halo stars, in- cluding the most iron-deficient star known, as well as stars in metal-poor globular clusters. The abundance pattern produced by this process and possible astrophysical sites are discussed. We also discuss a group of metal-poor stars that exhibit double enhancements of s- and r-process ele- ments, which have been recently discovered through observations of carbon-enhanced metal-poor stars. Observational constraints on the corresponding processes responsible for this signature are presented.

  1. An irradiation facility for Boron Neutron Capture Therapy application based on a radio frequency driven D-T neutron source and a new beam shaping assembly

    NASA Astrophysics Data System (ADS)

    Cerullo, Nicola; Esposito, Juan; Leung, Ka Ngo; Custodero, Salvatore

    2002-10-01

    A line of the Boron Neutron Capture Therapy (BNCT) research program aimed at the treatment of brain tumors, carried on at the Nuclear Departments of Pisa and Genova Universities (DIMNP and DITEC), is being focused on a new, 3H(d,n)4He (D-T), accelerator-based neutron source concept, developed at Lawrence Berkeley National Laboratory (LBNL). Simple and compact accelerator designs, using mixed D+ T+ ion beam with relatively low energy, 100 keV, have been developed which, in turn, can generate high neutron yields. New approaches have thus been started to design an epithermal neutron irradiation facility able to selectively slow the 14.1 MeV D-T neutrons down to the epithermal (1 eV-10 KeV) energy range. New neutron spectrum shifter and filtering materials, as well as different facility layout approaches have been tested. Possible beam shaping assembly models have also been designed. The research demonstrates that a D-T neutron source could be successfully implemented to provide a 1109 n/cm2 s epithermal neutron flux, in spite of its hard spectrum, although a generator device, able to yield 1014 n/s is, at present, not yet available. The latest Monte Carlo simulation of an accelerator-based facility, which relies on a single or multiple rf driven DT fusion neutron generator, is presented.

  2. Optimal Neutron Source & Beam Shaping Assembly for Boron Neutron Capture Therapy

    SciTech Connect

    J. Vujic; E. Greenspan; W.E. Kastenber; Y. Karni; D. Regev; J.M. Verbeke, K.N. Leung; D. Chivers; S. Guess; L. Kim; W. Waldron; Y. Zhu

    2003-04-30

    There were three objectives to this project: (1) The development of the 2-D Swan code for the optimization of the nuclear design of facilities for medical applications of radiation, radiation shields, blankets of accelerator-driven systems, fusion facilities, etc. (2) Identification of the maximum beam quality that can be obtained for Boron Neutron Capture Therapy (BNCT) from different reactor-, and accelerator-based neutron sources. The optimal beam-shaping assembly (BSA) design for each neutron source was also to e obtained. (3) Feasibility assessment of a new neutron source for NCT and other medical and industrial applications. This source consists of a state-of-the-art proton or deuteron accelerator driving and inherently safe, proliferation resistant, small subcritical fission assembly.

  3. 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.

  4. Design for an accelerator-based orthogonal epithermal neutron beam for boron neutron capture therapy.

    PubMed

    Allen, D A; Beynon, T D; Green, S

    1999-01-01

    This paper is concerned with the proposed Birmingham accelerator-based epithermal neutron beam for boron neutron capture therapy (BNCT). In particular, the option of producing a therapy beam at an orthogonal direction to the incoming protons is considered. Monte Carlo radiation transport simulations, both with and without a head phantom, have shown that an orthogonal beam geometry is not only acceptable but is indeed beneficial, in terms of a lower mean neutron energy and an enhanced therapeutic ratio for the same useful neutron fluence in the therapy beam. Typical treatment times for various beam options have been calculated, and range from 20 to 48 min with a 5 mA beam of 2.8 MeV protons, if the maximum photon-equivalent dose delivered to healthy tissue is to be 12.6 Gy Eq. The effects of proton beam diameter upon the therapy beam parameters have also been considered. PMID:9949400

  5. Improved monitoring system of neutron flux during boron-neutron capture therapy

    SciTech Connect

    Harasawa, S.; Nakamoto, A.; Hayakawa, Y.; Egawa, J.

    1981-10-01

    Continuous and simultaneous monitoring of neutron flux in the course of a boron-neutron capture operation on a brain tumor has been achieved using a new monitoring system. A silicon surface barrier diode mounted with /sup 6/LiF instead of the previously reported borax is used to sense neutrons. The pulse heights of /sup 3/H and ..cap alpha.. particles from /sup 6/Li(n, ..cap alpha..)/sup 2/H reaction are sufficiently high and well separated from noises due to ..gamma.. rays. The effect of pulse-height reduction due to the radiation damage of the diode thus becomes smaller, permitting continuous monitoring. The relative error of the monitoring is within 2% over 5 hr for a neutron-flux density of 2 x 10/sup 9/ n/cm/sup 2/ sec.

  6. Computational Dosimetry and Treatment Planning Considerations for Neutron Capture Therapy

    SciTech Connect

    Nigg, David Waler

    2003-03-01

    Specialized treatment planning software systems are generally required for neutron capture therapy (NCT) research and clinical applications. The standard simplifying approximations that work well for treatment planning computations in the case of many other modalities are usually not appropriate for application to neutron transport. One generally must obtain an explicit three-dimensional numerical solution of the governing transport equation, with energy-dependent neutron scattering completely taken into account. Treatment planning systems that have been successfully introduced for NCT applications over the past 15 years rely on the Monte Carlo stochastic simulation method for the necessary computations, primarily because of the geometric complexity of human anatomy. However, historically, there has also been interest in the application of deterministic methods, and there have been some practical developments in this area. Most recently, interest has turned toward the creation of treatment planning software that is not limited to any specific therapy modality, with NCT as only one of several applications. A key issue with NCT treatment planning has to do with boron quantification, and whether improved information concerning the spatial biodistribution of boron can be effectively used to improve the treatment planning process. Validation and benchmarking of computations for NCT are also of current developmental interest. Various institutions have their own procedures, but standard validation models are not yet in wide use.

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

    NASA Astrophysics Data System (ADS)

    Herrera, Mara S.; Gonzlez, Sara J.; Minsky, Daniel M.; Kreiner, Andrs 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.

  8. 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.

  9. Measurement of neutron capture cross sections by fast cyclic activation technique

    SciTech Connect

    Beer, H.; Kaeppeler, F.; Meibner, J.; Wiescher, M.; Schatz, H.M.; Sedyshev, P.V.; Popov, Yu.P.

    1994-12-31

    A fast cyclic neutron activation technique has been developed for astrophysically relevant Maxwellian averaged neutron capture (MAC) cross sections at 25keV thermal neutron energy. In the mass range of heavy elements the capture cross sections and isomeric ratios of the Kr, Xe, and Pt isotopes were determined, and from the light nuclei the capture cross sections of {sup 14}C, {sup 15}N, {sup 18}O, {sup 22}Ne, and {sup 36}S were measured.

  10. Design of an accelerator-based neutron source for neutron capture therapy.

    PubMed

    Terlizzi, R; Colonna, N; Colangelo, P; Maiorana, A; Marrone, S; Rain, A; Tagliente, G; Variale, V

    2009-07-01

    The boron neutron capture therapy is mainly suited in the treatment of some tumor kinds which revealed ineffective to the traditional radiotherapy. In order to take advantage of such a therapeutic modality in hospital environments, neutron beams of suitable energy and flux levels provided by compact size facilities are needed. The advantages and drawbacks of several neutron beams are here analysed in terms of therapeutic gains. In detail the GEANT-3/MICAP simulations show that high tumor control probability, with sub-lethal dose at healthy tissues, can be achieved by using neutron beams of few keV energy having a flux of about 10(9) neutrons/(cm(2)s). To produce such a neutron beam, the feasibility of a proton accelerator is investigated. In particular an appropriate choice of the radiofrequency parameters (modulation, efficiency of acceleration, phase shift, etc.) allows the development of relatively compact accelerators, having a proton beam current of 30 mA and an energy of 2 MeV, which could eventually lead to setting up of hospital-based neutron facilities. PMID:19406649

  11. Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator

    NASA Astrophysics Data System (ADS)

    Skalyga, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Maslennikova, A.; Volovecky, A.; Kalvas, T.; Koivisto, H.; Tarvainen, O.

    2014-12-01

    Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D-D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm2 is demonstrated. Estimations based on obtained experimental results show that neutron target bombarded by such deuteron beams would theoretically yield a neutron flux density up to 61010 cm-2/s. Thus, neutron generator based on a high-current deuteron ECR source with a powerful plasma heating by gyrotron radiation could fulfill the BNCT requirements significantly lower price, smaller size and ease of operation in comparison with existing reactors and accelerators.

  12. Neutron Tube Design Study for Boron Neutron Capture TherapyApplication

    SciTech Connect

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

    1998-01-04

    Radio-frequency (RF) driven ion sources are being developed in Lawrence Berkeley National Laboratory (LBNL) for sealed-accelerator-tube neutron generator application. By using a 5-cm-diameter RF-driven multicusp source H{sup +} yields over 95% have been achieved. These experimental findings will enable one to develop compact neutron generators based on the D-D or D-T fusion reactions. In this new neutron generator, the ion source, the accelerator and the target are all housed in a sealed metal container without external pumping. Recent moderator design simulation studies have shown that 14 MeV neutrons could be moderated to therapeutically useful energy ranges for boron neutron capture therapy (BNCT). The dose near the center of the brain with optimized moderators is about 65% higher than the dose obtained from a typical neutron spectrum produced by the Brookhaven Medical Research Reactor (BMRR), and is comparable to the dose obtained by other accelerator-based neutron sources. With a 120 keV and 1 A deuteron beam, a treatment time of {approx}35 minutes is estimated for BNCT.

  13. Conceptual design of a medical reactor for neutron capture therapy

    SciTech Connect

    Neuman, W.A.; Jones, J.L. )

    1990-10-01

    A conceptual design of a passively safe reactor facility for boron neutron capture therapy is presented. The facility configuration and its neutronic, thermal hydraulic, and safety issues are addressed in order to demonstrate the deployability of reactor technology for routine patient treatments and advanced research and dosimetry. The reactor has a power level of <10 MW (thermal) and is based on low-enriched UZrH fuel. The reactor facility generates a clean epithermal neutron beam capable of treating deep-seated brain tumors ([approximately] 70 mm) in <10 min. The incident fast neutron and gamma-ray contaminants in the beam are 1.8 and 0.4 Gy, respectively, for a 20-Gy therapeutic dose to a deep-seated tumor. With an expected operation schedule of [approximately]2,000 treatment periods per year, the reactor core lifetime is equal to the 30-yr facility lifetime and no refueling is necessary. Five beam ports are available for simultaneous patient treatments allowing between 2,000 and 10,000 treatments per year with expansion capabilities of at least threefold for 24 h/day operation. The cost per patient treatment is small, about $1,000, making the therapy very affordable. The reactor system design includes several passive safety features that allow the reactor to respond in a safe and benign manner in the event of off-normal transients. The response for various instantaneous reactivity insertions is assessed. Results show the reactor can passively respond to a reactivity insertion of 2 dollars such that the maximum temperature limits of the fuel are not exceeded.

  14. Stellar Isotopic Abundances in the Milky Way: Insights into the Origin of Carbon and Neutron-Capture Elements

    NASA Astrophysics Data System (ADS)

    Guo, Michelle; Zhang, A.; Kirby, E. N.; Guhathakurta, P.

    2014-01-01

    Elements heavier than iron are formed by the capture of neutrons onto lighter nuclei. Neutron capture happens via two separate processes: the rapid neutron capture process (r-process) that occurs in supernovae, and slow neutron capture process (s-process) that occurs in less-massive stars. This work used high-resolution spectroscopy, synthetic model spectra, and a least-squares fit to show that the ratio of 12C to 13C increases proportionally with [Fe/H]. The new results agree with the conclusions of Lucatello et al. (2006) and Frebel (2008), and show significant improvement that contains less scattering of data points. Analysis of the obtained isotope ratios suggests that the carbon in most stars of the sample originated in supernovae. This paper also presents a method to calculate the europium isotope ratio by modeling the shapes of absorption lines. The range of europium isotopic ratios agrees with previous theoretical predictions about the classical model of heavy element nucleosynthesis, and the work presents new insight into the origins of life in the universe. We thank the US National Science Foundation, the UCSC Science Internship Program, and the Lick Observatory where the spectra were obtained.

  15. FUSE Observations of Neutron-Capture Elements in Wolf-Rayet Planetary Nebulae

    NASA Astrophysics Data System (ADS)

    Dinerstein, H.

    We propose to obtain FUSE observations of planetary nebula central stars of the WC Wolf-Rayet ([WC]) class, in order to search for the products of neutron-capture processes in these stars and provide constraints on their evolutionary status. Although the origin of the [WC]'s is controversial, their H-deficient, C-rich surface compositions indicate that they have experienced a high degree of mixing and/or mass loss. Thus one might expect the nebulae they produce to show enhanced concentrations of He-burning and other nuclear products, such as nuclei produced by slow neutron capture during the AGB phase. We have already detected an absorption line from one such element, Germanium (Sterling, Dinerstein, & Bowers 2002), while conducting a search for H2 absorption from nebular molecular material FUSE GI programs A085 and B069). Since the strongest Ge enhancements were found in PNe with [WC] central stars, we propose to enlarge the sample of such objects observed by FUSE. THIS TEMPORARY AND PARTIAL SCRIPT COVERS ONE TARGET, HE 2-99, AND REQUESTS AN EXPOSURE TIME OF 15 KSEC. PHASE 2 INFORMATION FOR THE REMAINDER OF THE PROGRAM'S TOTAL TIME ALLOCATION OF 60 KSEC WILL BE SUBMITTED AT A LATER TIME.

  16. Modification of the University of Washington Neutron Radiotherapy Facility for optimization of neutron capture enhanced fast-neutron therapy

    SciTech Connect

    Nigg, David W.; Wemple, Charles A.; Risler, Ruedi; Hartwell, John K.; Harker, Yale D.; Laramore, George E.

    2000-02-01

    A modified neutron production target assembly has been developed to provide improved performance of the proton-cyclotron-based neutron radiotherapy facility at the University of Washington for applications involving neutron capture enhanced fast-neutron therapy. The new target produces a neutron beam that yields essentially the same fast-neutron physical depth-dose distribution as is produced by the current UW clinical system, but that also has an increased fraction of BNCT enhancement relative to the total therapeutic dose. The modified target is composed of a 5-millimeter layer of beryllium, followed by a 2.5-millimeter layer of tungsten, with a water-cooled copper backing. Measurements of the free-field neutron spectrum of the beam produced by the new target were performed using activation foils with a direct spectral unfolding technique. Water phantom measurements were performed using a tissue-equivalent ion chamber to characterize the fast-neutron depth-dose curve and sodium activation in soda-lime glass beads to characterize the thermal-neutron flux (and thus the expected neutron capture dose enhancement) as a function of depth. The results of the various measurements were quite consistent with expectations based on the design calculations for the modified target. The spectrum of the neutron beam produced by the new target features an enhanced low-energy flux component relative to the spectrum of the beam produced by the standard UW target. However, it has essentially the same high-energy neutron flux, with a reduced flux component in the mid-range of the energy spectrum. As a result, the measured physical depth-dose curve in a large water phantom has the same shape compared to the case of the standard UW clinical beam, but approximately twice the level of BNCT enhancement per unit background neutron dose at depths of clinical interest. In-vivo clinical testing of BNCT-enhanced fast-neutron therapy for canine lung tumors using the new beam was recently initiated. (c) 2000 American Association of Physicists in Medicine.

  17. Neutron Capture Cross Section Calculations with the Statistical Model

    NASA Astrophysics Data System (ADS)

    Beard, Mary; Uberseder, Ethan; Wiescher, Michael

    2014-09-01

    Hauser-Feshbach (HF) cross sections are of enormous importance for a wide range of applications, from waste transmutation and nuclear technologies, to medical applications, and nuclear astrophysics. It is a well observed result that different nuclear input models sensitively affect HF cross section calculations. Less well-known however are the effects on calculations originating from model-specific implementation details (such as level density parameter, matching energy, backshift and giant dipole parameters), as well as effects from non-model aspects, such as experimental data truncation and transmission function energy binning. To investigate the effects or these various aspects, Maxwellian-averaged neutron capture cross sections have been calculated for approximately 340 nuclei. The relative effects of these model details will be discussed.

  18. Neutron Capture and Fission Measurements on Actinides at Dance

    NASA Astrophysics Data System (ADS)

    Chyzh, A.; Wu, C. Y.; Kwan, E.; Henderson, R. A.; Gostic, J. M.; Ullmann, J. L.; Bredeweg, T. A.; Jandel, M.; Couture, A. J.; O'Donnell, J. M.; Haight, R. C.; Lee, H. Y.

    2013-03-01

    The prompt ?-ray energy and multiplicity distributions in the spontaneous fission of 252Cf have been measured using a highly granular 4? ?-ray calorimeter. Corrections were made for both energy and multiplicity distributions according to the detector response, which is simulated numerically using a model validated with the ?-ray calibration sources. A comparison of the total ?ray energy distribution was made between the measurement and a simulation by random sampling of the corrected ?-ray energy and multiplicity distributions through the detector response. A reasonable agreement is achieved between the measurement and simulation, indicating weak correlations between ?-ray energy and multiplicity. Moreover, the increasing agreement with increasing multiplicity manifests the stochastic aspect of the prompt ? decay in spontaneous fission. This calorimeter was designed for the study of neutron capture reactions and an example is given, where the238Pu(n, ?) measurement was carried out in the laboratory environment for the first time.

  19. Scissors mode of Gd nuclei studied from resonance neutron capture

    SciTech Connect

    Kroll, J.; Baramsai, B.; Becker, J. A.; and others

    2012-10-20

    Spectra of {gamma} rays following the neutron capture at isolated resonances of stable Gd nuclei were measured. The objectives were to get new information on photon strength of {sup 153,155-159}Gd with emphasis on the role of the M1 scissors-mode vibration. An analysis of the data obtained clearly indicates that the scissors mode is coupled not only to the ground state, but also to all excited levels of the nuclei studied. The specificity of our approach ensures unbiasedness in estimating the sumed scissors-mode strength {Sigma}B(M1){up_arrow}, even for odd product nuclei, for which conventional nuclear resonance fluorescence measurements yield only limited information. Our analysis indicates that for these nuclei the sum {Sigma}B(M1){up_arrow} increases with A and for {sup 157,159}Gd it is significantly higher compared to {sup 156,158}Gd.

  20. PGNAA of human arthritic synovium for boron neutron capture synovectomy

    SciTech Connect

    Binello, E.; Yanch, J.C.; Shortkroff, S.

    1997-12-01

    Boron neutron capture synovectomy (BNCS), is a proposed new therapy modality for the treatment of rheumatoid arthritis, an autoimmune disease afflicting the joints. The synovium, which is the membrane lining the joint, becomes inflamed and represents the target tissue for therapy. When a joint is unresponsive to drug treatment, physical removal of the synovium, termed synovectomy, becomes necessary. Existing options include surgery and radiation synovectomy. BNCS has advantages over these options in that it is noninvasive and does not require the administration of radioactive substances. Previous studies have shown that the uptake of {sup 10}B by human arthritic synovium ex vivo is high, ranging from 194 to 545 ppm with an unenriched boron compound. While tissue samples remain viable up to 1 week, ex vivo conditions do not accurately reflect those in vivo. This paper presents results from experiments assessing the washout of boron from the tissue and examines the implications for in vivo studies.

  1. Uncertainties in Hauser-Feshbach Neutron Capture Calculations for Astrophysics

    SciTech Connect

    Bertolli, M.G. Kawano, T.; Little, H.

    2014-06-15

    The calculation of neutron capture cross sections in a statistical Hauser-Feshbach method has proved successful in numerous astrophysical applications. Of increasing interest is the uncertainty associated with the calculated Maxwellian averaged cross sections (MACS). Aspects of a statistical model that introduce a large amount of uncertainty are the level density model, γ-ray strength function parameter, and the placement of E{sub low} – the cut-off energy below which the Hauser-Feshbach method is not applicable. Utilizing the Los Alamos statistical model code CoH3 we investigate the appropriate treatment of these sources of uncertainty via systematics of nuclei in a local region for which experimental or evaluated data is available. In order to show the impact of uncertainty analysis on nuclear data for astrophysical applications, these new uncertainties will be propagated through the nucleosynthesis code NuGrid.

  2. Scissors mode of Gd nuclei studied from resonance neutron capture

    NASA Astrophysics Data System (ADS)

    Kroll, J.; Baramsai, B.; Becker, J. A.; Be?vr, F.; Bredeweg, T. A.; Couture, A.; Chyzh, A.; Dashdorj, D.; Haight, R. C.; Heil, M.; Jandel, M.; Kppeler, F.; Krti?ka, M.; Mitchell, G. E.; O'Donnell, J. M.; Parker, W.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Vieira, D. J.; Walker, C. L.; Wilhelmy, J. B.; Wouters, J. M.; Wu, C. Y.

    2012-10-01

    Spectra of ? rays following the neutron capture at isolated resonances of stable Gd nuclei weremeasured. The objectives were to get new information on photon strength of 153,155-159Gd with emphasis on the role of the M1 scissors-mode vibration. An analysis of the data obtained clearly indicates that the scissors mode is coupled not only to the ground state, but also to all excited levels of the nuclei studied. The specificity of our approach ensures unbiasedness in estimating the sumed scissors-mode strength ?B(M1)?, even for odd product nuclei, for which conventional nuclear resonance fluorescence measurements yield only limited information. Our analysis indicates that for these nuclei the sum ?B(M1)? increases with A and for 157,159Gd it is significantly higher compared to 156,158Gd.

  3. Epithermal neutron formation for boron neutron capture therapy by adiabatic resonance crossing concept

    NASA Astrophysics Data System (ADS)

    Khorshidi, A.; Ghafoori-Fard, H.; Sadeghi, M.

    2014-05-01

    Low-energy protons from the cyclotron in the range of 15-30 MeV and low current have been simulated on beryllium (Be) target with a lead moderator around the target. This research was accomplished to design an epithermal neutron beam for Boron Neutron Capture Therapy (BNCT) using the moderated neutron on the average produced from 9Be target via (p, xn) reaction in Adiabatic Resonance Crossing (ARC) concept. Generation of neutron to proton ratio, energy distribution, flux and dose components in head phantom have been simulated by MCNP5 code. The reflector and collimator were designed in prevention and collimation of derivation neutrons from proton bombarding. The scalp-skull-brain phantom consisting of bone and brain equivalent material has been simulated in order to evaluate the dosimetric effect on the brain. Results of this analysis demonstrated while the proton energy decreased, the dose factor altered according to filters thickness. The maximum epithermal flux revealed using fluental, Fe and bismuth (Bi) filters with thicknesses of 9.4, 3 and 2 cm, respectively and also the epithermal to thermal neutron flux ratio was 103.85. The potential of the ARC method to replace or complement the current reactor-based supply sources of BNCT purposes.

  4. Gadolinium as an element for neutron capture therapy

    SciTech Connect

    Brugger, R.M.; Liu, H.B.; Laster, B.H.; Gordon, C.R.; Greenberg, D.D.; Warkentien, L.S.

    1992-12-31

    At BNL, preparations are being made to test in vitro compounds containing Gd and compare their response to the response of GD-DTPA to determine if one or several compounds can be located that enter the cells and enhance the Auger effect. Two similar rotators with positions for cell vials that have been constructed for these tests. The first rotator is made of only paraffin which simulates healthy tissue and provides control curves. The second rotator has 135 ppM of Gd-157 in the paraffin to simulate a Gd loaded tumor. Cells are irradiated in vials in the paraffin rotator and in the Gd-paraffin rotator at the epithermal beam of the Brookhaven Medical Research Reactor (BMRR). This produces an irradiation similar to what a patient would receive In an actual treatment. A combination of irradiations are made with both rotators; with no Gd compound or IdUrd In the cell media, with only Gd compound in the cell media and with both Gd compound and IdUrd in the cell media. The first set shows the effects of gamma rays from the H(n,gamma) reaction and the prompt gamma rays from capture of neutrons by Gd. The second set shows if there is any effect of Gd being in the cell media or inside the cells, i.e., an Auger effect. The third set shows the effect of enhancement by the IdUrd produced by the gamma rays from neutrons captured by either H or Gd. The fourth set combines all of the reactions and enhancements. Preliminary calculations and physical measurements of the doses that the cells will receive In these rotators have been made.

  5. Gadolinium as an element for neutron capture therapy

    SciTech Connect

    Brugger, R.M.; Liu, H.B.; Laster, B.H.; Gordon, C.R.; Greenberg, D.D.; Warkentien, L.S.

    1992-01-01

    At BNL, preparations are being made to test in vitro compounds containing Gd and compare their response to the response of GD-DTPA to determine if one or several compounds can be located that enter the cells and enhance the Auger effect. Two similar rotators with positions for cell vials that have been constructed for these tests. The first rotator is made of only paraffin which simulates healthy tissue and provides control curves. The second rotator has 135 ppM of Gd-157 in the paraffin to simulate a Gd loaded tumor. Cells are irradiated in vials in the paraffin rotator and in the Gd-paraffin rotator at the epithermal beam of the Brookhaven Medical Research Reactor (BMRR). This produces an irradiation similar to what a patient would receive In an actual treatment. A combination of irradiations are made with both rotators; with no Gd compound or IdUrd In the cell media, with only Gd compound in the cell media and with both Gd compound and IdUrd in the cell media. The first set shows the effects of gamma rays from the H(n,gamma) reaction and the prompt gamma rays from capture of neutrons by Gd. The second set shows if there is any effect of Gd being in the cell media or inside the cells, i.e., an Auger effect. The third set shows the effect of enhancement by the IdUrd produced by the gamma rays from neutrons captured by either H or Gd. The fourth set combines all of the reactions and enhancements. Preliminary calculations and physical measurements of the doses that the cells will receive In these rotators have been made.

  6. Neutron single particle structure in 131Sn and direct neutron capture cross sections

    SciTech Connect

    Kozub, R. L.; Arbanas, Goran; Adekola, A. S.; Bardayan, Daniel W; Blackmon, Jeffery C; Chae, Kyung Yuk; Chipps, K.; Cizewski, J. A.; Erikson, Luke; Hatarik, Robert; Hix, William Raphael; Jones, K. L.; Krolas, W.; Liang, J Felix; Ma, Z.; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; Pain, Steven D; Shapira, Dan; ShrinerJr., J. F.; Smith, Michael Scott; Swan, T. P.

    2012-01-01

    Recent calculations suggest that the rate of neutron capture by 130Sn has a significant impact on late-time nucleosynthesis in the r-process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r- process reaction rates may be strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, the (d, p) reaction has been studied in inverse kinematics using a 630 MeV beam of 130Sn (4.8 MeV/u) and a (CD2)n target. An array of Si strip detectors, including SIDAR and an early implementation of the ORRUBA, was used to detect reaction products. Results for the 130Sn(d, p)131Sn reaction are found to be very similar to those from the previously reported 132Sn(d, p)133Sn reaction. Direct-semidirect (n, ) cross section calculations, based for the first time on experimental data, are presented. The uncertainties in these cross sections are thus reduced by orders of magnitude from previous estimates.

  7. Neutron single particle structure in 131Sn and direct neutron capture cross sections.

    PubMed

    Kozub, R L; Arbanas, G; Adekola, A S; Bardayan, D W; Blackmon, J C; Chae, K Y; Chipps, K A; Cizewski, J A; Erikson, L; Hatarik, R; Hix, W R; Jones, K L; Krolas, W; Liang, J F; Ma, Z; Matei, C; Moazen, B H; Nesaraja, C D; Pain, S D; Shapira, D; Shriner, J F; Smith, M S; Swan, T P

    2012-10-26

    Recent calculations suggest that the rate of neutron capture by (130)Sn has a significant impact on late-time nucleosynthesis in the r process. Direct capture into low-lying bound states is expected to be significant in neutron capture near the N=82 closed shell, so r-process reaction rates may be strongly impacted by the properties of neutron single particle states in this region. In order to investigate these properties, the (d,p) reaction has been studied in inverse kinematics using a 630 MeV beam of (130)Sn (4.8 MeV/u) and a (CD(2))(n) target. An array of Si strip detectors, including the Silicon Detector Array and an early implementation of the Oak Ridge Rutgers University Barrel Array, was used to detect reaction products. Results for the (130)Sn(d, p)(131)Sn reaction are found to be very similar to those from the previously reported (132)Sn(d, p)(133)Sn reaction. Direct-semidirect (n,γ) cross section calculations, based for the first time on experimental data, are presented. The uncertainties in these cross sections are thus reduced by orders of magnitude from previous estimates. PMID:23215181

  8. A shielding design for an accelerator-based neutron source for boron neutron capture therapy.

    PubMed

    Hawk, A E; Blue, T E; Woollard, J E

    2004-11-01

    Research in boron neutron capture therapy (BNCT) at The Ohio State University Nuclear Engineering Department has been primarily focused on delivering a high quality neutron field for use in BNCT using an accelerator-based neutron source (ABNS). An ABNS for BNCT is composed of a proton accelerator, a high-energy beam transport system, a (7)Li target, a target heat removal system (HRS), a moderator assembly, and a treatment room. The intent of this paper is to demonstrate the advantages of a shielded moderator assembly design, in terms of material requirements necessary to adequately protect radiation personnel located outside a treatment room for BNCT, over an unshielded moderator assembly design. PMID:15308187

  9. Fast neutron thermalization and capture gamma-ray generation in soils

    SciTech Connect

    Shue, S.L.; Faw, R.E.; Shultis, J.K.

    1996-12-31

    The penetration of 14-MeV neutrons into five representative soils is investigated with two independent neutron transport calculational procedures. From Monte Carlo and discrete-ordinates codes, the spatial distribution of the thermal fluence and the capture of neutrons in the soils is determined for two neutron source geometries. Finally, empirical approximations of the thermal neutron fluence in the soil are presented for use in PGNAA of contaminants in the soil.

  10. Investigation of the tungsten isotopes via thermal neutron capture

    NASA Astrophysics Data System (ADS)

    Hurst, A. M.; Firestone, R. B.; Sleaford, B. W.; Summers, N. C.; Rvay, Zs.; Szentmiklsi, L.; Basunia, M. S.; Belgya, T.; Escher, J. E.; Krti?ka, M.

    2014-01-01

    Total radiative thermal neutron-capture ?-ray cross sections for the 182,183,184,186W isotopes were measured using guided neutron beams from the Budapest Research Reactor to induce prompt and delayed ? rays from natural and isotopically-enriched tungsten targets. These cross sections were determined from the sum of measured ?-ray cross sections feeding the ground state from low-lying levels below a cutoff energy, Ecrit, where the level scheme is completely known, and continuum ? rays from levels above Ecrit, calculated using the Monte Carlo statistical-decay code dicebox. The new cross sections determined in this work for the tungsten nuclides are ?0(182W)=20.5(14) b and ?11/2+(183Wm,5.2s )=0.177(18) b; ?0(183W)=9.37(38) b and ?5-(184Wm,8.33?s )=0.0247(55) b; ?0(184W)=1.43(10) b and ?11/2+(185Wm,1.67min)=0.0062(16) b; and, ?0(186W)=33.33(62) b and ?9/2+(187Wm,1.38?s)=0.400(16) b. These results are consistent with earlier measurements in the literature. The 186W cross section was also independently confirmed from an activation measurement, following the decay of 187W, yielding values for ?0(186W) that are consistent with our prompt ?-ray measurement. The cross-section measurements were found to be insensitive to choice of level density or photon strength model and only weakly dependent on Ecrit. Total radiative-capture widths calculated with dicebox showed much greater model dependence; however, the recommended values could be reproduced with selected model choices. The decay schemes for all tungsten isotopes were improved in these analyses. We were also able to determine new neutron-separation energies from our primary ?-ray measurements for the respective (n ,?) compounds: 183W [Sn=6190.88(6) keV]; 184W [Sn=7411.11(13) keV]; 185W [Sn=5753.74(5) keV]; and, 187W [Sn=5466.62(7) keV].

  11. Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments

    SciTech Connect

    Trbovich, M J; Barry, D P; Slovacek, R E; Danon, Y; Block, R C; Francis, N C; Lubert, M; Burke, J A; Drindak, N J; Lienweber, G; Ballad, R

    2007-02-06

    The focus of this work is to determine the resonance parameters for stable hafnium isotopes in the 0.005 - 200 eV region, with special emphasis on the overlapping {sup 176}Hf and {sup 178}Hf resonances near 8 eV. Accurate hafnium cross sections and resonance parameters are needed in order to quantify the effects of hafnium found in zirconium, a metal commonly used in reactors. The accuracy of the cross sections and the corresponding resonance parameters used in current nuclear analysis tools are rapidly becoming the limiting factor in reducing the overall uncertainty on reactor physics calculations. Experiments measuring neutron capture and transmission are routinely performed at the Rensselaer Polytechnic Institute (RPI) LINAC using the time-of flight technique. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m, respectively. Capture experiments were performed using a sixteen section NaI multiplicity detector at a flight path length of 25 m. These experiments utilized several thicknesses of metallic and isotope-enriched liquid Hf samples. The liquid Hf samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analyses were performed using the R-matrix Bayesian code SAMMY. A combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005 - 200 eV. Additionally, resonance integrals were calculated, along with errors for each hafnium isotope, using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than previous values. The {sup 176}Hf resonance integral, based on this work, is approximately 73% higher than the ENDF/B-VI value. This is due primarily to the changes to resonance parameters in the 8 eV resonance, the neutron width presented in this work is more than twice that of the previous value. The calculated elemental hafnium resonance integral however, changed very little.

  12. Spin precession of slow neutrons in Einstein-Cartan gravity with torsion, chameleon, and magnetic field

    NASA Astrophysics Data System (ADS)

    Ivanov, A. N.; Wellenzohn, M.

    2016-02-01

    We analyze a spin precession of slow neutrons in the Einstein-Cartan gravity with torsion, chameleon and magnetic field. For the derivation of the Heisenberg equation of motion of the neutron spin we use the effective low-energy potential, derived by Ivanov and Wellenzohn [Phys. Rev. D 92, 125004 (2015)] for slow neutrons, coupled to gravitational, chameleon, and torsion fields to order 1 /m , where m is the neutron mass. In addition to these low-energy interactions we switch on the interaction of slow neutrons with a magnetic field. We show that to linear order approximation with respect to gravitational, chameleon, and torsion fields the Dirac Hamilton operator for fermions (neutrons), moving in spacetimes created by rotating coordinate systems, contains the anti-Hermitian operators of torsion-fermion (neutron) interactions, caused by torsion scalar and tensor space-space-time and time-space-space degrees of freedom. Such anti-Hermitian operators violate C P and T invariance. In the low-energy approximation the C P and T violating torsion-fermion (neutron) interactions appear only to order O (1 /m ). One may assume that in the rotating Universe and galaxies the obtained anti-Hermitian torsion-fermion interactions might be an origin of (i) violation of C P and T invariance in the Universe and (ii) of baryon asymmetry. We show that anti-Hermitian torsion-fermion interactions of relativistic fermions, violating C P and T invariance, (i) cannot be removed by nonunitary transformations of the Dirac fermion wave functions and (ii) are conformal invariant. According to general requirements of conformal invariance of massive particle theories in gravitational fields [see R. H. Dicke, Phys. Rev. 125, 2163 (1962) and A. J. Silenko, Phys. Rev. D 91, 065012 (2015)], conformal invariance of anti-Hermitian torsion-fermion interactions is valid only if the fermion mass is changed by a conformal factor.

  13. New insights on Ba overabundance in open clusters. Evidence for the intermediate neutron-capture process at play?

    NASA Astrophysics Data System (ADS)

    Mishenina, T.; Pignatari, M.; Carraro, G.; Kovtyukh, V.; Monaco, L.; Korotin, S.; Shereta, E.; Yegorova, I.; Herwig, F.

    2015-02-01

    Recently, an increasing number of studies were devoted to measure the abundances of neutron-capture elements heavier than iron in stars belonging to Galactic Open Clusters (OCs). OCs span a sizeable range in metallicity (-0.6 ≤ [Fe/H] ≤ +0.4), and they show abundances of light elements similar to disc stars of the same age. A different pattern is observed for heavy elements. A large scatter is observed for Ba, with most OCs showing [Ba/Fe] and [Ba/La] overabundant with respect to the Sun. The origin of this overabundance is not clearly understood. With the goal of providing new observational insights, we determined radial velocities, atmospheric parameters and chemical composition of 27 giant stars members of five OCs: Cr 110, Cr 261, NGC 2477, NGC 2506 and NGC 5822. We used high-resolution spectra obtained with the UVES spectrograph at European Southern Observatory Paranal. We perform a detailed spectroscopic analysis of these stars to measure the abundance of up to 22 elements per star. We study the dependence of element abundance on metallicity and age with unprecedented detail, complementing our analysis with data culled from the literature. We confirm the trend of Ba overabundance in OCs, and show its large dispersion for clusters younger than ˜4 Gyr. Finally, the implications of our results for stellar nucleosynthesis are discussed. We show in this work that the Ba enrichment compared to other neutron-capture elements in OCs cannot be explained by the contributions from the slow neutron-capture process and the rapid neutron-capture process. Instead, we argue that this anomalous signature can be explained by assuming an additional contribution by the intermediate neutron-capture process.

  14. Continuum quasiparticle random-phase approximation for astrophysical direct neutron capture reactions on neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Matsuo, Masayuki

    2015-03-01

    I formulate a many-body theory to calculate the cross section of direct radiative neutron capture reaction by means of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random-phase approximation (QRPA). A focus is put on very-neutron-rich nuclei and low-energy neutron kinetic energy in the range from 1 keV to several MeV, which is relevant to the rapid neutron capture process of nucleosynthesis. I begin with the photoabsorption cross section and the E 1 strength function. Next, in order to apply the reciprocity theorem, I decompose the cross section into partial cross sections corresponding to different channels of one- and two-neutron emission decays of photo-excited states. A numerical example is shown for the photo-absorption of 142Sn and the neutron capture of 141Sn .

  15. A NEW SINGLE-CRYSTAL FILTERED THERMAL NEUTRON SOURCE FOR NEUTRON CAPTURE THERAPY RESEARCH AT THE UNIVERSITY OF MISSOURI

    SciTech Connect

    John D. Brockman; David W. Nigg; M. Frederick Hawthorne

    2008-09-01

    Parameter studies, design calculations and initial neutronic performance measurements have been completed for a new thermal neutron beamline to be used for neutron capture therapy cell and small-animal radiobiology studies at the University of Missouri Research Reactor. The beamline features the use of single-crystal silicon and bismuth sections for neutron filtering and for reduction of incident gamma radiation. The calculated and measured thermal neutron flux produced at the irradiation location is on the order of 9.5x108 neutrons/cm2-s, with a measured cadmium ratio (Au foils) of 105, indicating a well-thermalized spectrum.

  16. 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

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

    PubMed

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

    2015-03-01

    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 10(5) n/cm(2)/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

  18. 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.}

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

    PubMed

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

    1998-09-01

    The 7Li(p,n)7Be 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/AlF3, 7LiF, and D2O, 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 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/AlF3 or 7LiF 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% higher doses near the midline of the brain. For a single beam treatment, a proton beam current of 20 mA, and a 7LiF 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. PMID:9775379

  20. Landmine detection method combined with backscattering neutrons and capture γ-rays from hydrogen.

    PubMed

    Takahashi, Yoshiyuki; Misawa, Tsuyoshi; Pyeon, Cheol Ho; Shiroya, Seiji; Yoshikawa, Kiyoshi

    2011-07-01

    The usefulness of the measurements of the backscattering neutron and 2.22MeV capture γ-ray from hydrogen in the landmine detection method is described in this paper. When the soil moisture content is increased, the reaction rates of both the neutron scattering reaction and capture reaction are increased. However, the backscattering neutrons are more influenced than the capture γ-rays by the soil moisture before the reaction with the detector. The facts that the backscattering neutron method is useful in the dry soil case and that the capture γ-ray method is effective in well-wet soil case are confirmed by the experiments and the calculations. The landmine detection efficiency is improved in various soil moisture conditions by combining the backscattering neutron method together with the capture γ-ray method. The effectiveness of the pulse mode operation was confirmed numerically. PMID:21481597

  1. Effect of diameter of nanoparticles and capture cross-section library on macroscopic dose enhancement in boron neutron capture therapy

    PubMed Central

    Farhood, Bagher

    2014-01-01

    Purpose The aim of this study is evaluation of the effect of diameter of 10B nanoparticles and various neutron capture cross-section libraries on macroscopic dose enhancement in boron neutron capture therapy (BNCT). Material and methods MCNPX Monte Carlo code was used for simulation of a 252Cf source, a soft tissue phantom and a tumor containing 10B nanoparticles. Using 252Cf as a neutron source, macroscopic dose enhancement factor (MDEF) and total dose rate in tumor in the presence of 100, 200, and 500 ppm of 10B nanoparticles with 25 nm, 50 nm, and 100 nm diameters were calculated. Additionally, the effect of ENDF, JEFF, JENDL, and CENDL neutron capture cross-section libraries on MDEF was evaluated. Results There is not a linear relationship between the average MDEF value and nanoparticles’ diameter but the average MDEF grows with increased concentration of 10B nanoparticles. There is an increasing trend for average MDEF with the tumor distance. The average MDEF values were obtained the same for various neutron capture cross-section libraries. The maximum and minimum doses that effect on the total dose in tumor were neutron and secondary photon doses, respectively. Furthermore, the boron capture related dose component reduced in some extent with increase of diameter of 10B nanoparticles. Conclusions Based on the results of this study, it can be concluded that from physical point of view, various nanoparticle diameters have no dominant effect on average MDEF value in tumor. Furthermore, it is concluded that various neutron capture cross-section libraries are resulted to the same macroscopic dose enhancements. However, it is predicted that taking into account the biological effects for various nanoparticle diameters will result in different dose enhancements. PMID:25834582

  2. Feasibility study on epithermal neutron field for cyclotron-based boron neutron capture therapy.

    PubMed

    Yonai, Shunsuke; Aoki, Takao; Nakamura, Takashi; Yashima, Hiroshi; Baba, Mamoru; Yokobori, Hitoshi; Tahara, Yoshihisa

    2003-08-01

    To realize the accelerator-based boron neutron capture therapy (BNCT) at the Cyclotron and Radioisotope Center of Tohoku University, the feasibility of a cyclotron-based BNCT was evaluated. This study focuses on optimizing the epithermal neutron field with an energy spectrum and intensity suitable for BNCT for various combinations of neutron-producing reactions and moderator materials. Neutrons emitted at 90 degrees from a thick (stopping-length) Ta target, bombarded by 50 MeV protons of 300 microA beam current, were selected as a neutron source, based on the measurement of angular distributions and neutron energy spectra. As assembly composed of iron, AlF3/Al/6LiF, and lead was chosen as moderators, based on the simulation trials using the MCNPX code. The depth dose distributions in a cylindrical phantom, calculated with the MCNPX code, showed that, within 1 h of therapeutic time, the best moderator assembly, which is 30-cm-thick iron, 39-cm-thick AlF3/Al/6LiF, and 1-cm-thick lead, provides an epithermal neutron flux of 0.7 x 10(9) [n cm(-2) s(-1)]. This results in a tumor dose of 20.9 Gy-eq at a depth of 8 cm in the phantom, which is 6.4 Gy-eq higher than that of the Brookhaven Medical Research Reactor at the equivalent condition of maximum normal tissue tolerance. The beam power of the cyclotron is 15 kW, which is much lower than other accelerator-based BNCT proposals. PMID:12945968

  3. Accelerator-based epithermal neutron beam design for neutron capture therapy.

    PubMed

    Yanch, J C; Zhou, X L; Shefer, R E; Klinkowstein, R E

    1992-01-01

    Recent interest in the production of epithermal neutrons for use in boron neutron capture therapy (BNCT) has promoted an investigation into the feasibility of generating such neutrons with a high current proton accelerator. Energetic protons (2.5 MeV) on a 7Li target produce a spectrum of neutrons with maximum energy of roughly 800 keV. A number of combinations of D2O moderator, lead reflector, 6Li thermal neutron filtration, and D2O/6Li shielding will result in a useful epithermal flux of 1.6 x 10(8) n/s at the patient position. The neutron beam is capable of delivering 3000 RBE-cGy to a tumor at a depth of 7.5 cm in a total treatment time of 60-93 min (depending on RBE values used and based on a 24-cm diameter x 19-cm length D2O moderator). Treatment of deeper tumors with therapeutic advantage would also be possible. Maximum advantage depths (RBE weighted) of 8.2-9.2 (again depending on RBE values and precise moderator configuration) are obtained in a right-circular cylindrical phantom composed of brain-equivalent material with an advantage ratio of 4.7-6.3. A tandem cascade accelerator (TCA), designed and constructed at Science Research Laboratory (SRL) in Somerville MA, can provide the required proton beam parameters for BNCT of deep-seated tumors. An optimized configuration of materials required to shift the accelerator neutron spectrum down to therapeutically useful energies has been designed using Monte Carlo simulation in the Whitaker College Biomedical Imaging and Computation Laboratory at MIT. Actual construction of the moderator/reflector assembly is currently underway. PMID:1324392

  4. Continuum dipole response near the threshold and the direct neutron capture cross section at astrophysical energies

    NASA Astrophysics Data System (ADS)

    Matsuo, Masayuki

    2013-07-01

    We apply the continuum quasiparticle random phase approximation to calculate the direct neutron capture cross section relevant to the r-process nucleo-synthesis. The electric dipole strength function in an even-even n-rich nucleus is decomposed with respect to the channels of direct neutron decays. Using the detailed balance relation, the partial dipole strengths are converted to obtain the direct neutron-capture cross sections. Numerical examples are given for 142Sn.

  5. The Detector for Advanced Neutron Capture Experiments: A 4{pi} BaF2 Detector for Neutron Capture Measurements at LANSCE

    SciTech Connect

    Ullmann, J.L.; Esch, E.-I.; Haight, R.C.; Hunt, L.; O'Donnell, J.M.; Reifarth, R.; Agvaanluvsan, U.; Alpizar, A.; Hatarik, R.; Bond, E.M.; Bredeweg, T.A.; Kronenberg, A.; Rundberg, R.S.; Vieira, D.J.; Wilhelmy, J.B.; Folden, C.M.; Hoffman, D.C.; Greife, U.; Schwantes, J.M.; Strottman, D.D.

    2005-05-24

    The Detector for Advanced Neutron Capture Experiments (DANCE) is a 162-element 4{pi} BaF2 array designed to make neutron capture cross-section measurements on rare or radioactive targets with masses as little as one milligram. Accurate capture cross sections are needed in many research areas, including stellar nucleosynthesis, advanced nuclear fuel cycles, waste transmutation, and other applied programs. These cross sections are difficult to calculate accurately and must be measured. The design and initial performance results of DANCE is discussed.

  6. Measured Total Cross Sections of Slow Neutrons Scattered by Solid Deuterium and Implications for Ultracold Neutron Sources

    SciTech Connect

    Atchison, F.; Blau, B.; Brandt, B. van den; Brys, T.; Daum, M.; Fierlinger, P.; Hautle, P.; Henneck, R.; Heule, S.; Kirch, K.; Kohlbrecher, J.; Kuehne, G.; Konter, J.A.; Pichlmaier, A.; Wokaun, A.; Bodek, K.; Kasprzak, M.; Kuzniak, M.; Geltenbort, P.; Zmeskal, J.

    2005-10-28

    The total scattering cross sections for slow neutrons with energies in the range 100 neV to 3 meV for solid ortho-{sup 2}H{sub 2} at 18 and 5 K, frozen from the liquid, have been measured. The 18 K cross sections are found to be in excellent agreement with theoretical expectations and for ultracold neutrons dominated by thermal up scattering. At 5 K the total scattering cross sections are found to be dominated by the crystal defects originating in temperature induced stress but not deteriorated by temperature cycles between 5 and 10 K.

  7. Measured total cross sections of slow neutrons scattered by solid deuterium and implications for ultracold neutron sources.

    PubMed

    Atchison, F; Blau, B; van den Brandt, B; Bry?, T; Daum, M; Fierlinger, P; Hautle, P; Henneck, R; Heule, S; Kirch, K; Kohlbrecher, J; Khne, G; Konter, J A; Pichlmaier, A; Wokaun, A; Bodek, K; Kasprzak, M; Ku?niak, M; Geltenbort, P; Zmeskal, J

    2005-10-28

    The total scattering cross sections for slow neutrons with energies in the range 100 neV to 3 meV for solid ortho-2H2 at 18 and 5 K, frozen from the liquid, have been measured. The 18 K cross sections are found to be in excellent agreement with theoretical expectations and for ultracold neutrons dominated by thermal up scattering. At 5 K the total scattering cross sections are found to be dominated by the crystal defects originating in temperature induced stress but not deteriorated by temperature cycles between 5 and 10 K. PMID:16383898

  8. Boron neutron capture therapy at the crossroads: challenges and opportunities.

    PubMed

    Barth, Rolf F

    2009-07-01

    Over the past 25 years research on boron neutron capture therapy (BNCT) has progressed relatively slowly but steadily with the greatest progress in the field of clinical studies. These specifically have included the use of BNCT to treat a variety of malignancies other than high grade gliomas and melanomas. However, there are a number of key areas where little, if any, significant progress has been made. First and foremost among these has been the lack of new boron delivery agents. Improvement in drug delivery and the development of the best dosing paradigms for both boronophenylalanine (BPA) and sodium borocaptate (BSH) are of major importance and these still have not been optimized. Dosimetry for BNCT is still imprecise and is based on treating to normal tissue tolerance, based on blood boron values, rather than any real-time information on the boron content of the residual tumor that is to be irradiated. Another major problem has been the total dependence on nuclear reactors as neutron sources for BNCT. However, this will change in the near future when a clinically useful accelerator comes into use in 2009. Like it or not, in order to gain the credibility of a broad community of physicians who treat brain tumor patients, there will have to be a randomized clinical trial. Finally, BNCT will have to compete with new therapeutic approaches that are less costly and more effective for the treatment of brain tumors. These challenges notwithstanding, BNCT can fill an important niche for those malignancies, whether primary or recurrent, for which there is currently no effective therapy. PMID:19467879

  9. MCNP speed advances for boron neutron capture therapy

    SciTech Connect

    Goorley, J.T.; McKinney, G.; Adams, K.; Estes, G.

    1998-04-01

    The Boron Neutron Capture Therapy (BNCT) treatment planning process of the Beth Israel Deaconess Medical Center-M.I.T team relies on MCNP to determine dose rates in the subject`s head for various beam orientations. In this time consuming computational process, four or five potential beams are investigated. Of these, one or two final beams are selected and thoroughly evaluated. Recent advances greatly decreased the time needed to do these MCNP calculations. Two modifications to the new MCNP4B source code, lattice tally and tracking enhancements, reduced the wall-clock run times of a typical one million source neutrons run to one hour twenty five minutes on a 200 MHz Pentium Pro computer running Linux and using the GNU FORTRAN compiler. Previously these jobs used a special version of MCNP4AB created by Everett Redmond, which completed in two hours two minutes. In addition to this 30% speedup, the MCNP4B version was adapted for use with Parallel Virtual Machine (PVM) on personal computers running the Linux operating system. MCNP, using PVM, can be run on multiple computers simultaneously, offering a factor of speedup roughly the same as the number of computers used. With two 200 MHz Pentium Pro machines, the run time was reduced to forty five minutes, a 1.9 factor of improvement over the single Linux computer. While the time of a single run was greatly reduced, the advantages associated with PVM derive from using computational power not already used. Four possible beams, currently requiring four separate runs, could be run faster when each is individually run on a single machine under Windows NT, rather than using Linux and PVM to run one after another with each multiprocessed across four computers. It would be advantageous, however, to use PVM to distribute the final two beam orientations over four computers.

  10. Muon capture on the deuteron and the neutron-neutron scattering length

    NASA Astrophysics Data System (ADS)

    Marcucci, L. E.; Machleidt, R.

    2014-11-01

    Background: We consider the muon capture reaction μ-+2H→νμ+n +n , which presents a "clean" two-neutron (n n ) system in the final state. We study here its capture rate in the doublet hyperfine initial state (ΓD). The total capture rate for the muon capture μ-+3He→νμ+3H (Γ0) is also analyzed, although, in this case, the n n system is not so clean anymore. Purpose: We investigate whether ΓD (and Γ0) could be sensitive to the n n S -wave scattering length (an n), and we check on the possibility to extract an n from an accurate measurement of ΓD. Method: The muon capture reactions are studied with nuclear potentials and charge-changing weak currents, derived within chiral effective field theory. The next-to-next-to-next-to-leading-order chiral potential with cutoff parameter Λ =500 MeV is used, but the low-energy constant (LEC) determining an n is varied so as to obtain an n=-18.95 ,-16.0 ,-22.0 , and +18.22 fm. The first value is the present empirical one, while the last one is chosen such as to lead to a di-neutron bound system with a binding energy of 139 keV. The LEC's cD and cE, present in the three-nucleon potential and axial-vector current (cD), are constrained to reproduce the A =3 binding energies and the triton Gamow-Teller matrix element. Results: The capture rate ΓD is found to be 399 (3 ) s-1 for an n=-18.95 and -16.0 fm; and 400 (3 ) s-1 for an n=-22.0 fm. However, in the case of an n=+18.22 fm, the result of 275 (3 ) s-1 [ 135 (3 ) s-1 ] is obtained, when the di-neutron system in the final state is unbound (bound). The total capture rate Γ0 for muon capture on 3He is found to be 1494(15), 1491(16), 1488(18), and 1475(16) s-1 for an n=-18.95 ,-16.0 ,-22.0 , and +18.22 fm, respectively. All the theoretical uncertainties are due to the fitting procedure and radiative corrections. Conclusions: Our results seem to exclude the possibility of constraining a negative an n with an uncertainty of less than ˜±3 fm through an accurate determination of the muon capture rates, but the uncertainty on the present empirical value will not complicate the interpretation of the (forthcoming) experimental results for ΓD. Finally, a comparison with the already available experimental data discourages the possibility of a bound di-neutron state (positive an n).

  11. Computational characterization and experimental validation of the thermal neutron source for neutron capture therapy research at the University of Missouri

    SciTech Connect

    Broekman, J. D.; Nigg, D. W.; Hawthorne, M. F.

    2013-07-01

    Parameter studies, design calculations and neutronic performance measurements have been completed for a new thermal neutron beamline constructed for neutron capture therapy cell and small-animal radiobiology studies at the University of Missouri Research Reactor. The beamline features the use of single-crystal silicon and bismuth sections for neutron filtering and for reduction of incident gamma radiation. The computational models used for the final beam design and performance evaluation are based on coupled discrete-ordinates and Monte Carlo techniques that permit detailed modeling of the neutron transmission properties of the filtering crystals with very few approximations. Validation protocols based on neutron activation spectrometry measurements and rigorous least-square adjustment techniques show that the beam produces a neutron spectrum that has the anticipated level of thermal neutron flux and a somewhat higher than expected, but radio-biologically insignificant, epithermal neutron flux component. (authors)

  12. Neutron induced brachytherapy: a combination of neutron capture therapy and brachytherapy.

    PubMed

    Shih, J L; Brugger, R M

    1992-01-01

    Brachytherapy is a widely used radiation therapy modality while neutron capture therapy is being intensely studied. These methods provide some advantages, but also have limitations that might be ameliorated by combining them. A technique that uses stable solid seeds or needles of Gd which are irradiated in vivo with neutrons has been evaluated. Monte Carlo calculations show that 5000 cGy of prompt gamma dose can be delivered to a treatment volume of 40 cm3 with a three-plane implant of 9-Gd needles. The tumor to normal tissue advantage of this method is as good as brachytherapy using 60Co seeds. Measurements of prompt gamma dose with films and TLD-700s in a lucite phantom verify the Monte Carlo evaluation. Dose measurements of a Gd needle in air also show that Gd is promising for this form of brachytherapy. PMID:1584135

  13. Toward a final design for the Birmingham boron neutron capture therapy neutron beam.

    PubMed

    Allen, D A; Beynon, T D; Green, S; James, N D

    1999-01-01

    This paper is concerned with the proposed Birmingham accelerator-based epithermal neutron beam for boron neutron capture therapy (BNCT). Details of the final moderator design, such as beam delimiter, shield, and beam exit surface shape are considered. Monte Carlo radiation transport simulations with a head and body phantom have shown that a simple flat moderator beam exit surface is preferable to the previously envisioned spherical design. Dose rates to individual body organs during treatment have been calculated using a standard MIRD phantom. We have shown that a simple polyethylene shield, doped with natural lithium, is sufficient to provide adequate protection to the rest of the body during head irradiations. The effect upon the head phantom dose distributions of the use of such a shield to delimit the therapy beam has been evaluated. PMID:9949401

  14. Production of heavy and superheavy neutron-rich nuclei in neutron capture processes

    NASA Astrophysics Data System (ADS)

    Zagrebaev, V. I.; Karpov, A. V.; Mishustin, I. N.; Greiner, Walter

    2011-10-01

    The neutron capture process is considered as an alternative method for production of superheavy (SH) nuclei. Strong neutron fluxes might be provided by nuclear reactors and nuclear explosions in the laboratory frame and by supernova explosions in nature. All these cases are discussed in the paper. There are two gaps of short-lived nuclei (one is the well-known fermium gap and the other one is located in the region of Z=106-108 and N˜170) which impede the formation of SH nuclei by rather weak neutron fluxes realized at available nuclear reactors. We find that in the course of multiple (rather “soft”) nuclear explosions these gaps may be easily bypassed, and thus, a measurable amount of the neutron-rich long-living SH nuclei located at the island of stability may be synthesized. Existing pulsed reactors do not allow one to bypass these gaps. We formulate requirements for the pulsed reactors of the next generation that could be used for production of long-living SH nuclei. Natural formation of SH nuclei (in supernova explosions) is also discussed. The yield of SH nuclei relative to lead is estimated to be about 10-12, which is not beyond the experimental sensitivity for a search of SH elements in cosmic rays.

  15. Thermal neutron irradiation field design for boron neutron capture therapy of human explanted liver

    SciTech Connect

    Bortolussi, S.; Altieri, S.

    2007-12-15

    The selective uptake of boron by tumors compared to that by healthy tissue makes boron neutron capture therapy (BNCT) an extremely advantageous technique for the treatment of tumors that affect a whole vital organ. An example is represented by colon adenocarcinoma metastases invading the liver, often resulting in a fatal outcome, even if surgical resection of the primary tumor is successful. BNCT can be performed by irradiating the explanted organ in a suitable neutron field. In the thermal column of the Triga Mark II reactor at Pavia University, a facility was created for this purpose and used for the irradiation of explanted human livers. The neutron field distribution inside the organ was studied both experimentally and by means of the Monte Carlo N-particle transport code (MCNP). The liver was modeled as a spherical segment in MCNP and a hepatic-equivalent solution was used as an experimental phantom. In the as-built facility, the ratio between maximum and minimum flux values inside the phantom ({phi}{sub max}/{phi}{sub min}) was 3.8; this value can be lowered to 2.3 by rotating the liver during the irradiation. In this study, the authors proposed a new facility configuration to achieve a uniform thermal neutron flux distribution in the liver. They showed that a {phi}{sub max}/{phi}{sub min} ratio of 1.4 could be obtained without the need for organ rotation. Flux distributions and dose volume histograms were reported for different graphite configurations.

  16. An integrated design of an accelerator-based neutron source for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Dobelbower, Michael Christian

    1997-07-01

    An Accelerator Based Neutron Source (ABNS) for Boron Neutron Capture Therapy (BNCT) was first proposed at The Ohio State University (OSU). Since the conception of the ABNS for BNCT, OSU has designed and optimized a moderator assembly based on in-air and in-phantom parameters. Additionally, the fabrication of the moderator assembly has commenced along with detailed analyses of the target and its heat removal system. In this dissertation, an integrated design of the ABNS is presented. This integrated design includes the high energy beam transport system (HEBT), the target and heat removal system (HRS), and the moderator assembly. In the integration process, a neutronic model of the HRS was developed and incorporated into the moderator assembly model. Additionally, a preliminary design of a HEBT system was developed that is compatible with both the HRS and the facility shielding. This dissertation also includes the completion of the fabrication of the moderator assembly and its experimental verification. The completion of the moderator assembly fabrication included the refabrication of the moderator and delimiter and the fabrication of the 6Li covering on the front of the moderator assembly. The experimental verification included neutron spectrum calculations and measurements in the irradiation port, and 3He detector response calculations and measurements in-phantom downstream of the moderator assembly.

  17. Comparison of statistical model calculations for stable isotope neutron capture

    NASA Astrophysics Data System (ADS)

    Beard, M.; Uberseder, E.; Crowter, R.; Wiescher, M.

    2014-09-01

    It is a well-observed result that different nuclear input models sensitively affect Hauser-Feshbach (HF) cross-section calculations. Less well-known, however, are the effects on calculations originating from nonmodel aspects, such as experimental data truncation and transmission function energy binning, as well as code-dependent aspects, such as the definition of level-density matching energy and the inclusion of shell correction terms in the level-density parameter. To investigate these aspects, Maxwellian-averaged neutron capture cross sections (MACS) at 30 keV have been calculated using the well-established statistical Hauser-Feshbach model codes talys and non-smoker for approximately 340 nuclei. For the same nuclei, MACS predictions have also been obtained using two new HF codes, cigar and sapphire. Details of these two codes, which have been developed to contain an overlapping set of identically implemented nuclear physics input models, are presented. It is generally accepted that HF calculations are valid to within a factor of 3. It was found that this factor is dependent on both model and nonmodel details, such as the coarseness of the transmission function energy binning and data truncation, as well as variances in details regarding the implementation of level-density parameter, backshift, matching energy, and giant dipole strength function parameters.

  18. Neutron Capture Cross Section Measurement on $^{238}$Pu at DANCE

    SciTech Connect

    Chyzh, A; Wu, C Y

    2011-02-14

    The proposed neutron capture measurement for {sup 238}Pu was carried out in Nov-Dec, 2010, using the DANCE array at LANSCE, LANL. The total beam-on-target time is about 14 days plus additional 5 days for the background measurement. The target was prepared at LLNL with the new electrplating cell capable of plating the {sup 238}Pu isotope simultaneously on both sides of the 3-{micro}m thick Ti backing foil. A total mass of 395 {micro}g with an activity of 6.8 mCi was deposited onto the area of 7 mm in diameter. The {sup 238}Pu sample was enriched to 99.35%. The target was covered by 1.4 {micro}m double-side aluminized mylar and then inserted into a specially designed vacuum-tight container, shown in Fig. 1, for the {sup 238}Pu containment. The container was tested for leaks in the vacuum chamber at LLNL. An identical container without {sup 238}Pu was made as well and used as a blank for the background measurement.

  19. Neutron rms radius and electric polarizability from data on the interaction of slow neutrons with bismuth

    SciTech Connect

    Aleksandrov, Y.A.; Vrana, M.; Manrique, G.J.; Machekhina, T.A.; Sedlakova, L.N.

    1986-12-01

    The energy dependence of the total neutron cross section of bismuth has been measured in the neutron-energy range from 1 to 90 eV. The results are analyzed together with similar data existing in the literature. The value of the neutron rms radius is found to be /sup 1/2//sub N/ = -0.11 +- 0.02 F. This result is compared with theoretical calculations in the framework of the quark cloudy bag model. An estimate of the neutron electric polarizability ..cap alpha../sub n/<5x10/sup -3/ F/sup 3/ is obtained.

  20. Systematic Measurement of keV-neutron Capture Cross Sections and Capture Gamma-ray Spectra of Sn Isotopes

    SciTech Connect

    Nishiyama, J.; Igashira, M.; Ohsaki, T.; Kim, G. N.; Chung, W. C.; Ro, T. I.

    2006-03-13

    The capture cross sections and capture {gamma}-ray spectra of 117,119Sn were measured in an incident neutron energy region from 10 to 100 keV and at 570 keV, using a 1.5-ns pulsed neutron source by the 7Li(p,n)7Be reaction and a large anti-Compton NaI(Tl) {gamma}-ray spectrometer. A pulse-height weighting technique was applied to observed capture {gamma}-ray pulse-height spectra to derive capture yields. The capture cross sections of 117,119Sn were obtained with the error of about 5% by using the standard capture cross sections of 197Au. The present cross sections were compared with previous experimental data and the evaluated values in JENDL-3.3 and ENDF/B-VI. The capture {gamma}-ray spectra of 117,119Sn were derived by unfolding the observed capture {gamma}-ray pulse-height spectra.

  1. Accelerator-based epithermal neutron sources for boron neutron capture therapy of brain tumors.

    PubMed

    Blue, Thomas E; Yanch, Jacquelyn C

    2003-01-01

    This paper reviews the development of low-energy light ion accelerator-based neutron sources (ABNSs) for the treatment of brain tumors through an intact scalp and skull using boron neutron capture therapy (BNCT). A major advantage of an ABNS for BNCT over reactor-based neutron sources is the potential for siting within a hospital. Consequently, light-ion accelerators that are injectors to larger machines in high-energy physics facilities are not considered. An ABNS for BNCT is composed of: (1) the accelerator hardware for producing a high current charged particle beam, (2) an appropriate neutron-producing target and target heat removal system (HRS), and (3) a moderator/reflector assembly to render the flux energy spectrum of neutrons produced in the target suitable for patient irradiation. As a consequence of the efforts of researchers throughout the world, progress has been made on the design, manufacture, and testing of these three major components. Although an ABNS facility has not yet been built that has optimally assembled these three components, the feasibility of clinically useful ABNSs has been clearly established. Both electrostatic and radio frequency linear accelerators of reasonable cost (approximately 1.5 M dollars) appear to be capable of producing charged particle beams, with combinations of accelerated particle energy (a few MeV) and beam currents (approximately 10 mA) that are suitable for a hospital-based ABNS for BNCT. The specific accelerator performance requirements depend upon the charged particle reaction by which neutrons are produced in the target and the clinical requirements for neutron field quality and intensity. The accelerator performance requirements are more demanding for beryllium than for lithium as a target. However, beryllium targets are more easily cooled. The accelerator performance requirements are also more demanding for greater neutron field quality and intensity. Target HRSs that are based on submerged-jet impingement and the use of microchannels have emerged as viable target cooling options. Neutron fields for reactor-based neutron sources provide an obvious basis of comparison for ABNS field quality. This paper compares Monte Carlo calculations of neutron field quality for an ABNS and an idealized standard reactor neutron field (ISRNF). The comparison shows that with lithium as a target, an ABNS can create a neutron field with a field quality that is significantly better (by a factor of approximately 1.2, as judged by the relative biological effectiveness (RBE)-dose that can be delivered to a tumor at a depth of 6cm) than that for the ISRNF. Also, for a beam current of 10 mA, the treatment time is calculated to be reasonable (approximately 30 min) for the boron concentrations that have been assumed. PMID:12749700

  2. Determination and production of an optimal neutron energy spectrum for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Bleuel, Darren Leo

    An accelerator-based neutron irradiation facility employing an electrostatic quadrupole (ESQ) accelerator for Boron Neutron Capture Therapy (BNCT) has been proposed at Lawrence Berkeley National Laboratory. In this dissertation, the properties of an ideal neutron beam for delivering a maximized dose to a glioblastoma multiforme tumor in a reasonable time while minimizing the dose to healthy tissue is examined. A variety of materials, beam shaping assemblies, and neutron sources were considered to deliver a neutron spectrum as close to the calculated idealized spectrum as possible. Several optimization studies were performed to determine the best proton energy and moderator material to maximize the efficacy of an accelerator-based BNCT facility utilizing the 7Li(p,n)7Be reaction as a neutron source. A new, faster method of performing such an optimization was developed, known as the "Ubertally" method, in which data from a single Monte Carlo simulation is reweighted to produce results for any neutron spatial, energy and angular source distribution. Results were confirmed experimentally at Lawrence Berkeley National Laboratory's 88? cyclotron. Thermal fluxes in this experiment were found to be approximately 30% lower than expected, but the depth-dose profile was confirmed to within 8% maximum deviation. A final beam shaping assembly is then recommended. Utilizing a material known as Fluental as a moderating material, deep-seated tumor doses 50% higher than that delivered by clinical trials at the Brookhaven Medical Research Reactor (BMRR) are predicted. The final recommended design should contain a 37 cm thickness of Fluental(TM) moderator, a 1--2 cm gamma shield, an Al2O3 reflector, a V-shaped aluminum-backed or copper-backed source with heavy water cooling, and a 13 cm lithiated polyethylene delimiter. This design would be operated at 2.4 MeV proton energy at 20 mA to conduct treatments in less than an hour and a half. However, this design may be easily altered depending on the changing needs of the treatment facility. It is therefore concluded that production of an accelerator-based BNCT facility using an ESQ accelerator and a 7Li target is feasible and can produce a superior quality neutron beam.

  3. Self-shielding effects in neutron spectra measurements for neutron capture therapy by means of activation foils.

    PubMed

    Pytel, Krzysztof; Józefowicz, Krystyna; Pytel, Beatrycze; Koziel, Alina

    2004-01-01

    The design and optimisation of a neutron beam for neutron capture therapy (NCT) is accompanied by the neutron spectra measurements at the target position. The method of activation detectors was applied for the neutron spectra measurements. Epithermal neutron energy region imposes the resonance structure of activation cross sections resulting in strong self-shielding effects. The neutron self-shielding correction factor was calculated using a simple analytical model of a single absorption event. Such a procedure has been applied to individual cross sections from pointwise ENDF/B-VI library and new corrected activation cross sections were introduced to a spectra unfolding algorithm. The method has been verified experimentally both for isotropic and for parallel neutron beams. Two sets of diluted and non-diluted activation foils covered with cadmium were irradiated in the neutron field. The comparison of activation rates of diluted and non-diluted foils has demonstrated the correctness of the applied self-shielding model. PMID:15353753

  4. Atomic analysis of the (n; t)-reaction of the helium-3 atoms with slow neutrons

    NASA Astrophysics Data System (ADS)

    Frolov, Alexei M.; Wardlaw, David M.

    2011-05-01

    Probabilities of formation of various hydrogenic species during the exothermic nuclear (n, 3He; t, p)-reaction of atomic helium-3 with slow neutrons are determined. In particular, we have found that the probability of forming the tritium atom 3H in its ground state is ?55.192 87 %, while the analogous probability of forming the protium atom 1H in its ground state is ?1.023 63%. Analogous probabilities of formation of the negatively charged hydrogen ions, i.e. the 3H- and 1H- ions, in the nuclear (n, 3He; t, p)-reaction with slow neutrons are ?7.8680% and ?0.065 83%, respectively. We also consider bremsstrahlung from fast fission-type reactions in atomic systems. The spectrum of emitted radiation is analysed.

  5. Neutron-Capture Nucleosynthesis and the Chemical Evolution of Globular Clusters

    NASA Astrophysics Data System (ADS)

    Shingles, Luke J.

    2015-09-01

    Elements heavier than iron are almost entirely produced in stars through neutron captures and radioactive decays. Of these heavy elements, roughly half are produced by the slow neutron-capture process (s-process), which takes place under extended exposure to low neutron densities. Most of the s-process production occurs in stars with initial masses between roughly 0.8 and 8 solar masses (Msun), which evolve through the Asymptotic Giant Branch (AGB) phase. This thesis explores several topics related to AGB stars and the s-process, with a focus on comparing theoretical models to observations in the literature on planetary nebulae, post-AGB stars, and globular cluster stars. A recurring theme is the uncertainty of carbon-13-pocket formation, which is crucial for building accurate models of s-process nucleosynthesis. We first investigated whether neutron-capture reactions in AGB stars are the cause of the low sulphur abundances in planetary nebulae and post-AGB stars relative to the interstellar medium. Accounting for uncertainties in the size of the partial mixing zone that forms carbon-13 pockets and the rates of neutron-capture and neutron-producing reactions, our models failed to reproduce the observed levels of sulphur destruction. From this, we concluded that AGB nucleosynthesis is not the cause of the sulphur anomaly. We also discovered a new method to constrain the extent of the partial mixing zone using neon abundances in planetary nebulae. We next aimed to discover the stellar sites of the s-process enrichment in globular clusters that have inter- and intra-cluster variation, with the examples of M4 (relative to M5) and M22, respectively. Using a new chemical evolution code developed by the candidate, we tested models with stellar yields from rotating massive stars and AGB stars. We compared our model predictions for the production of s-process elements with abundances from s-poor and s-rich populations. We found that rotating massive stars alone do not explain the pattern of abundance variations in either cluster, and that a contribution from AGB stars with carbon-13 pockets is required. We derived a minimum enrichment timescale from our best-fitting chemical evolution models and, although the value depends on the assumptions made about the formation of carbon-13 pockets, our estimate of 240 to 360 Myr for M22 is consistent with the upper limit of 300 Myr inferred by isochrone fitting. Lastly, there is accumulating evidence that some stars (e.g., in Omega Centauri) have been born with helium mass fractions as high as 40%. This motivated us to explore the impact of helium-rich abundances on the evolution and nucleosynthesis of intermediate-mass (3 to 6 Msun) AGB models. We found that the stellar yields of s-process elements are substantially lower in He-rich models, largely as a result of less intershell material being mixed into the envelope. We also found evidence that high He abundances could restrict the s-process production by carbon-13 pockets to stars with lower initial masses.

  6. 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.

  7. Recent Research with the Detector for Advanced Neutron Capture Experiments (dance) at the LOS Alamos Neutron Science Center

    NASA Astrophysics Data System (ADS)

    Ullmann, J. L.

    2014-09-01

    The DANCE detector at Los Alamos is a 160 element, nearly 4? BaF2 detector array designed to make measurements of neutron capture on rare or radioactive nuclides. It has also been used to make measurements of gamma-ray multiplicity following capture and gamma-ray output from fission. Several examples of measurements are briefly discussed.

  8. Neutron capture autoradiographic determination of 10B distributions and concentrations in biological samples for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Yanagie, Hironobu; Ogura, Koichi; Matsumoto, Toshio; Eriguchi, Masazumi; Kobayashi, Hisao

    1999-11-01

    It is necessary for effective boron neutron capture therapy (BNCT) to accumulate 10B atoms in the tumor cells. We prepared a cationic liposome entrapped 10B compound for the delivery system and examined the delivery capacity of 10B atoms to pancreatic cancer cell, AsPC-1, in vivo. It is required to achieve an accurate measurement of 10B distributions and concentrations in biological samples with a sensitivity in the ppm range for BNCT. We applied CR-39 (polyallyldiglycol carbonate) plastic track detectors to ?-autoradiographic measurements of the 10B biodistribution in sliced whole-body samples of mice. To selectively desensitize undesirable proton tracks, we applied PEW (KOH+C 2H 5OH+H 2O) solution to the etching of CR-39 detector. The subsequent use of an alpha-track radiographic image analysis system enabled a discrimination between alpha tracks and recoiled proton tracks by the track size selection method. This enabled us to estimate quantitatively the distributions of 10B concentrations within the tissue sections by comparing with suitable standards.

  9. Determining steam saturation in steam flooded oil reservoirs using pulsed neutron capture

    NASA Astrophysics Data System (ADS)

    Barnes, David Daniel

    Pulsed neutron capture (PNC) technique have played an important role in determining steam saturation, a key component to estimating residual oil volume in steamfloods. While experience using PNC tools has been good, recent results from three-dimensional neutron transport simulation suggest a critical failing in the prevailing techniques. At steam saturation above 50--70 saturation units, the leading parameter ceases to be sensitive to changes in steam volume leading to a large discrepancy between the predicted saturation and the actual saturation. These results are especially troubling as no means of calibrating tools in gas or steam filled formations is available. There are several phenomena known to influence PNC measurements including the diffusion effect, borehole effect, and spectral hardening. The hypothesis explored in this study is that one or more of these phenomena become exacerbated at high steam saturations. In addition, two new phenomena known as the transport effect and the slowing down effect are explored. These effects are investigated using analytical, deterministic, and Monte Carlo techniques to uncover how they change with steam saturation and attempt to model them. Among the effect explored in this study included spectral hardening and the local diffusion effect. Spectral hardening does play some role in the error seen at high saturation values, but it only account for about 5% of the difference seen in 90 su formations. Local diffusion describes how neutrons interact through the formation, spreading out as they diffuse away from the source. It is reasonable to suspect that the reduction of hydrogen caused by the introduction of steam results in a faster diffusion process as neutrons scatter less frequently. However, results do not support this hypothesis. Transport and slowing down are two other phenomena that may explain this error. Results suggest that transport theory predicts a faster decaying flux at 90 su than diffusion theory. Difficulties in obtaining the data necessary to investigate this hypothesis means an exhaustive investigation of this option is outside the scope of this thesis. Ultimately good progress has been made in the explanation of discrepancies seen at high steam saturations. The complexity of the problem precludes it from being resolved in any single study. In addition, experimental data is needed to confirm the simulation results and give an accurate measure of the magnitude of the error in real world environments.

  10. Neutron-Capture Abundances in the Milky Way: New Insights from Open Clusters

    NASA Astrophysics Data System (ADS)

    Overbeek, Jamie Christine; Friel, Eileen D.; Jacobson, Heather R.

    2016-01-01

    Recent spectroscopic studies of open clusters (OCs) show large increases in a few slow neutron-capture (s-process) element abundances, primarily Ba, for the youngest clusters, contradicting previous models of AGB star nucleosynthesis. These observations have prompted theorists to add new factors to models of low-mass (M < 1.5M⊙) AGB star interiors to inflate yields ad hoc. However, these supersolar abundances in young clusters are based primarily on Ba lines which are extremely strong in most OC stars and display hyperfine and isotopic structure. We have assembled a sample of 68 red giant stars from 23 OCs and have measured eleven neutron-capture elements; here we focus on Ba and five other s-process elements (La, Ce, Sr, Y, and Zr) to see if the trends with age match that observed for Ba. Our OC sample ranges in age from 0.2 - 10 Gyr and covers 7.5 < RGC < 16.5 kpc.We find that [Ba/Fe] with cluster age does have a large, statistically significant downward trend with age (~ -0.04 dex/Gyr), but all other s-process elements have more modest trends (~ -0.02 dex/Gyr) that are not as significant and are mostly driven by the oldest cluster in our sample, Be 17. We explore other correlations between families of s-process elements as well. The puzzle of the disagreement between Ba and other s-process abundances leads us to question the reliability of the commonly measured Ba lines.

  11. Boron neutron capture therapy of intracerebral rat gliosarcomas.

    PubMed Central

    Joel, D D; Fairchild, R G; Laissue, J A; Saraf, S K; Kalef-Ezra, J A; Slatkin, D N

    1990-01-01

    The efficacy of boron neutron capture therapy (BNCT) for the treatment of intracerebrally implanted rat gliosarcomas was tested. Preferential accumulation of 10B in tumors was achieved by continuous infusion of the sulfhydryl borane dimer, Na4(10)B24H22S2, at a rate of 45-50 micrograms of 10B per g of body weight per day from day 11 to day 14 after tumor initiation (day 0). This infusion schedule resulted in average blood 10B concentrations of 35 micrograms/ml in a group of 12 gliosarcoma-bearing rats and 45 micrograms/ml in a group of 10 similar gliosarcoma-bearing rats treated by BNCT. Estimated tumor 10B levels in these two groups were 26 and 34 micrograms/g, respectively. On day 14, boron-treated and non-boron-treated rats were exposed to 5.0 or 7.5 MW.min of radiation from the Brookhaven Medical Research Reactor that yielded thermal neutron fluences of approximately 2.0 x 10(12) or approximately 3.0 x 10(12) n/cm2, respectively, in the tumors. Untreated rats had a median postinitiation survival time of 21 days. Reactor radiation alone increased median postinitiation survival time to 26 (5.0 MW.min) or 28 (7.5 MW.min) days. The 12 rats that received 5 MW.min of BNCT had a median postinitiation survival time of 60 days. Two of these animals survived greater than 15 months. In the 7.5 MW.min group, the median survival time is not calculable since 6 of the 10 animals remain alive greater than 10 months after BNCT. The estimated radiation doses to tumors in the two BNCT groups were 14.2 and 25.6 Gy equivalents, respectively. Similar gliosarcoma-bearing rats treated with 15.0 or 22.5 Gy of 250-kilovolt peak x-rays had median survival times of only 26 or 31 days, respectively, after tumor initiation. Images PMID:2263630

  12. DANCE : a 4[pi] barium fluoride detector for measuring neutron capture on unstable nuclei /.

    SciTech Connect

    Ullmann, J. L.; Haight, Robert C.; Hunt, L. F.; Reifarth, R.; Rundberg, R. S.; Bredeweg, T. A.; Fowler, Malcolm M.; Miller, G. G.; Heil, M.; Kppeler, F.; Chamberlin, E. P.

    2002-01-01

    Measurements of neutron capture on unstable nuclei are important for studies of s-process nucleosynthesis, nuclear waste transmutation, and stewardship science. A 160-element, 4{pi} barium fluoride detector array, and associated neutron flight path, is being constructed to make capture measurements at the moderated neutron spallation source at LANSCE. Measurements can be made on as little as 1 mg of sample material over energies from near thermal to near 100 keV. The design of the DANCE array is described and neutron flux measurements from flight path commissioning are shown. The array is expected to be complete by the end of 2002.

  13. Carboranyl Nucleosides & Oligonucleotides for Neutron Capture Therapy Final Report

    SciTech Connect

    Schinazi, Raymond F.

    2004-12-01

    This proposal enabled us to synthesize and develop boron-rich nucleosides and oligonucleotide analogues for boron neutron capture therapy (BNCT) and the treatment of various malignancies. First, we determined the relationship between structure, cellular accumulation and tissue distribution of 5-o-carboranyl-2'-deoxyuridine (D-CDU) and its derivatives D-ribo-CU and 5-o-carboranyluracil (CU), to potentially target brain and other solid tumors for neutron capture therapy. Synthesized carborane containing nucleoside derivatives of CDU, D- and L-enantiomers of CDU, D-ribo-CU and CU were used. We measured tissue disposition in xenografted mice bearing 9479 human prostate tumors xenografts and in rats bearing 9L gliosarcoma isografts in their flanks and intracranially. The accumulation of D-CDU, 1-({beta}-L-arabinosyl)-5-o-carboranyluracil, D-ribo-CU, and CU were also studied in LnCap human prostate tumor cells and their retention was measured in male nude mice bearing LnCap and 9479 human prostate tumor xenografts. D-CDU, D-ribo-CU and CU levels were measured after administration in mice bearing 9479 human prostate tumors in their flanks. D-CDU achieved high cellular concentrations in LnCap cells and up to 2.5% of the total cellular compound was recovered in the 5'-monophosphorylated form. D-CDU cellular concentrations were similar in LnCap and 9479 tumor xenografts. Studies in tumor bearing animals indicated that increasing the number of hydroxyl moieties in the sugar constituent of the carboranyl nucleosides lead to increased rate and extent of renal elimination, a decrease in serum half-lives and an increased tissue specificity. Tumor/brain ratios were greatest for CDU and D-ribo-CU, while tumor/prostate ratios were greatest with CU. CDU and D-ribo-CU have potential for BNCT of brain malignancies, while CU may be further developed for prostate cancer. A method was developed for the solid phase synthesis of oligonucleotides containing (ocarboran-1-yl-methyl)phosphonate (CBMP) internucleotide group. Unmodified phosphodiester linkages were formed using a standard {beta}-cyanoethyl cycle and automated DNA synthesizer. Modified CBMP internucleotide linkage was produced using the phosphotriester method and 5'-O-monomethoxytritylthymidine 3'-O-[(o-carboran-1-yl-methyl)phosphonate] monomer. Several dodecathymidylic acids bearing modification at 3'- or 5'-end, or in the middle of oligonucleotide chain were synthesized. The resulting oligomers are being characterized by reverse phase high-pressure liquid chromatography (RP-HPLC), electrospray ionization mass spectrometry (ESIMS), ultraviolet spectroscopy (UV), and circular dichroism (CD). In collaboration with Cornell University, we employed a secondary ion mass spectrometry (SIMS) based subcellular isotopic imaging technique of ion microscopy for evaluating 4 carboranyl nucleosides. Nucleosides synthesized by our group, including CDU, HMCDU, CTU, and CFAU were tested for their boron delivery to the nuclear and cytoplasmic compartments of U251 human and F98 rat glioma cells. Quantitative SIMS analysis of boron was performed in cryogenically prepared cells. For all drugs, the cell cytoplasm revealed significantly higher boron than the nucleus. However, the boron partitioning between the cell nucleus and the nutrient medium indicated 6.4-10.6 times higher boron in the nucleus. The results suggested that these novel carboranyl nucleosides should provide efficient BNCT agents that accumulate in malignant cells and the need for further evaluations in vitro and in animal models.

  14. A Project of Boron Neutron Capture Therapy System based on a Proton Linac Neutron Source

    NASA Astrophysics Data System (ADS)

    Kiyanagi, Yoshikai; Asano, Kenji; Arakawa, Akihiro; Fukuchi, Shin; Hiraga, Fujio; Kimura, Kenju; Kobayashi, Hitoshi; Kubota, Michio; Kumada, Hiroaki; Matsumoto, Hiroshi; Matsumoto, Akira; Sakae, Takeji; Saitoh, Kimiaki; Shibata, Tokushi; Yoshioka, Masakazu

    At present, the clinical trials of Boron Neutron Capture Therapy (BNCT) are being performed at research reactor facilities. However, an accelerator based BNCT has a merit that it can be built in a hospital. So, we just launched a development project for the BNCT based on an accelerator in order to establish and to spread the BNCT as an effective therapy in the near future. In the project, a compact proton linac installed in a hospital will be applied as a neutron source, and energy of the proton beam is planned to be less than about 10 MeV to reduce the radioactivity. The BNCT requires epithermal neutron beam with an intensity of around 1x109 (n/cm2/sec) to deliver the therapeutic dose to a deeper region in a body and to complete the irradiation within an hour. From this condition, the current of the proton beam required is estimated to be a few mA on average. Enormous heat deposition in the target is a big issue. We are aiming at total optimization of the accelerator based BNCT from the linac to the irradiation position. Here, the outline of the project is introduced and the moderator design is presented.

  15. New compounds for neutron capture therapy (NCT) and their significance

    SciTech Connect

    Fairchild, R.G.; Bond, V.P.

    1982-01-01

    Clearly the most effective tumor therapy would be obtained by the selective targeting of cytotoxic agents to tumor cells. Although many biomolecules are known to be taken up in tumors, the targeting of cytotoxic agents to tumors is limited by the fact that other essential cell pools compete with equal or even greater effectiveness. The approach of delivering stable non-toxic isotopes to tumor, with activation by means of an external radiation beam, is advantageous for two reasons: (1) it obviates problems associated with high uptake of isotopes in normal tissues, as these cell pools can be excluded from the radiation field, and (2) the general tumor area can be included in the activating beam field; thus, the possibility exists that all microscopic tumor extensions can be irradiated. As long as range of reaction products is short, dose will be restricted to the tumor, with a resultant high therapeutic ratio. This method can be accomplished with either photon activation therapy (PAT) or Neutron Capture Therapy (NCT), the latter will be emphasized here. The range of the high LET, low OER particles from the /sup 10/B(n,..cap alpha..)/sup 7/Li reaction is approx. 10 ..mu..m, or one cell diameter; hence this reaction is optimal for cell killing. A number of biomolecules have been investigated as possible vehicles for transport of boron to tumors, including phenothiazines, thiouracils, porphyrins, nucleosides, and amino acids. Biodistributions of these compounds show selective concentration in tumor adequate for therapy. The biological halflives are in the order of days, allowing the possibility of fractionated or protracted irradiations. The radiobiological and physical implication of these parameters on NCT are discussed. The possibility of using an approximately-monoenergetic, scandium-filtered beam of about 2 keV, to reduce the dose from background radiations by about 85%, is also discussed. (ERB)

  16. Boron containing compounds and their preparation and use in neutron capture therapy

    DOEpatents

    Gabel, D.

    1992-09-01

    The present invention pertains to boron containing thiouracil derivatives, their method of preparations, and their use in the therapy of malignant melanoma using boron neutron capture therapy. No Drawings

  17. Thiourea derivatives, methods of their preparation and their use in neutron capture therapy of malignant melanoma

    DOEpatents

    Gabel, D.

    1991-06-04

    The present invention pertains to boron containing thiouracil derivatives, their method of preparations, and their use in the therapy of malignant melanoma using boron neutron capture therapy. No Drawings

  18. Neutron Capture Cross Section of 14C Studied by Intermediate-Energy Coulomb Dissociation

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Fukuda, N.

    2005-12-01

    The neutron capture reaction on 14C leading to the 15C ground state, which is important in the nucleo-synthesis processes in the universe, has been studied by using the Coulomb dissociation of 15C on a Pb target at 68 MeV/nucleon. The dissociation cross sections at large impact parameters over 20 fm has been translated into the energy spectrum of the neutron capture by using the principle of the detailed balance. The energy spectrum shows the typical p-wave capture characteristics, which is understood by the fact that the ground state of 15C is a loosely bound halo state. The present study suggests that such a p-wave neutron capture may often occur at the very neutron rich regions, where important nucleo-synthesis paths are expected.

  19. Exploration of direct neutron capture with covariant density functional theory inputs

    NASA Astrophysics Data System (ADS)

    Zhang, Shi-Sheng; Peng, Jin-Peng; Smith, M. S.; Arbanas, G.; Kozub, R. L.

    2015-04-01

    Predictions of direct neutron capture are of vital importance for simulations of nucleosynthesis in supernovae, merging neutron stars, and other astrophysical environments. We calculated direct capture cross sections using nuclear structure information obtained from a covariant density functional theory as input for the fresco coupled reaction channels code. We investigated the impact of pairing, spectroscopic factors, and optical potentials on our results to determine a robust method to calculate cross sections of direct neutron capture on exotic nuclei. Our predictions agree reasonably well with experimental cross section data for the closed shell nuclei 16O and 48Ca, and for the exotic nucleus 36S . We then used this approach to calculate the direct neutron capture cross section on the doubly magic unstable nucleus 132Sn which is of interest for the astrophysical r-process.

  20. 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.

  1. Development and construction of a neutron beam line for accelerator-based boron neutron capture synovectomy.

    PubMed

    Gierga, D P; Yanch, J C; Shefer, R E

    2000-01-01

    A potential application of the 10B(n, alpha)7Li nuclear reaction for the treatment of rheumatoid arthritis, termed Boron Neutron Capture Synovectomy (BNCS), is under investigation. In an arthritic joint, the synovial lining becomes inflamed and is a source of great pain and discomfort for the afflicted patient. The goal of BNCS is to ablate the synovium, thereby eliminating the symptoms of the arthritis. A BNCS treatment would consist of an intra-articular injection of boron followed by neutron irradiation of the joint. Monte Carlo radiation transport calculations have been used to develop an accelerator-based epithermal neutron beam line for BNCS treatments. The model includes a moderator/reflector assembly, neutron producing target, target cooling system, and arthritic joint phantom. Single and parallel opposed beam irradiations have been modeled for the human knee, human finger, and rabbit knee joints. Additional reflectors, placed to the side and back of the joint, have been added to the model and have been shown to improve treatment times and skin doses by about a factor of 2. Several neutron-producing charged particle reactions have been examined for BNCS, including the 9Be(p,n) reaction at proton energies of 4 and 3.7 MeV, the 9Be(d,n) reaction at deuteron energies of 1.5 and 2.6 MeV, and the 7Li(p,n) reaction at a proton energy of 2.5 MeV. For an accelerator beam current of 1 mA and synovial boron uptake of 1000 ppm, the time to deliver a therapy dose of 10,000 RBEcGy ranges from 3 to 48 min, depending on the treated joint and the neutron producing charged particle reaction. The whole-body effective dose that a human would incur during a knee treatment has been estimated to be 3.6 rem or 0.75 rem, for 1000 ppm or 19,000 ppm synovial boron uptake, respectively, although the shielding configuration has not yet been optimized. The Monte Carlo design process culminated in the construction, installation, and testing of a dedicated BNCS beam line on the high-current tandem electrostatic accelerator at the Laboratory for Accelerator Beam Applications at the Massachusetts Institute of Technology. PMID:10659758

  2. Neutron capture measurement on 173Lu at LANSCE with DANCE detector

    NASA Astrophysics Data System (ADS)

    Theroine, C.; Ebran, A.; Mot, V.; Roig, O.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Nortier, F. M.; O'Donnell, J. M.; Rundberg, R. S.; Taylor, W. A.; Ullmann, J. L.; Viera, D. J.; Wilhelmy, J. B.; Wouters, J. M.

    2013-06-01

    The (n,?) cross section on the unstable 173Lu(t1/2 = 1.37y) has been measured from thermal energy up to 200 eV at Los Alamos Neutron Science Center (LANSCE) with The Detector for Advanced Neutron Capture Experiements (DANCE). The main aim of this study is to validate and optimize reaction models for unstable nucleus. A preliminary capture yield will be presented in this paper.

  3. Measurement of the neutron capture cross sections of {sup 15}N and {sup 18}O

    SciTech Connect

    Meissner, J.; Schatz, H.; Herndl, H.; Wiescher, M.; Beer, H.; Kaeppeler, F.

    1995-02-05

    Preliminary experimental results are presented for neutron capture cross sections of {sup 15}N and {sup 18}O for neutron energies of 25, 152, 250, and 371 keV. The cross sections were used to calculate the capture reaction rates at stellar temperatures, around 0.1--1.0 GK. (AIP) {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  4. Neutron capture measurement on {sup 173}Lu at LANSCE with DANCE detector

    SciTech Connect

    Theroine, C.; Ebran, A.; Meot, V.; Roig, O.; Bond, E. M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Nortier, F. M.; O'Donnell, J. M.; Rundberg, R. S.; Taylor, W. A.; Ullmann, J. L.; Viera, D. J.; Wilhelmy, J. B.; Wouters, J. M.

    2013-06-10

    The (n,{gamma}) cross section on the unstable {sup 173}Lu(t{sub 1/2} = 1.37y) has been measured from thermal energy up to 200 eV at Los Alamos Neutron Science Center (LANSCE) with The Detector for Advanced Neutron Capture Experiements (DANCE). The main aim of this study is to validate and optimize reaction models for unstable nucleus. A preliminary capture yield will be presented in this paper.

  5. Initial Performance Characterization for a Thermalized Neutron Beam for Neutron Capture Therapy Research at Washington State University

    SciTech Connect

    David W. Nigg; P.E> Sloan; J.R. Venhuizen; C.A. Wemple

    2005-11-01

    The Idaho National Engineering and Environmental Laboratory (INEEL) and Washington State University (WSU) have constructed a new epithermal-neutron beam for collaborative Boron Neutron Capture Therapy (BNCT) preclinical research at the WSU TRIGATM research reactor facility1. More recently, additional beamline components were developed to permit the optional thermalization of the beam for certain types of studies where it is advantageous to use a thermal neutron source rather than an epithermal source. This article summarizes the results of some initial neutronic performance measurements for the thermalized system, with a comparison to the expected performance from the design computations.

  6. An investigation of the feasibility of gadolinium for neutron capture synovectomy.

    PubMed

    Gierga, D P; Yanch, J C; Shefer, R E

    2000-07-01

    Neutron capture synovectomy (NCS) has been proposed as a possible treatment modality for rheumatoid arthritis. Neutron capture synovectomy is a two-part modality, in which a compound containing an isotope with an appreciable thermal neutron capture cross section is injected directly into the joint, followed by irradiation with a neutron beam. Investigations to date for NCS have focused on boron neutron capture synovectomy (BNCS), which utilizes the 10B(n,alpha)7Li nuclear reaction to deliver a highly localized dose to the synovium. This paper examines the feasibility of gadolinium, specifically 157Gd, as an alternative to boron as a neutron capture agent for NCS. This alternative modality is termed Gadolinium Neutron Capture Synovectomy, or GNCS. Monte Carlo simulations have been used to compare 10B and 157Gd as isotopes for accelerator-based NCS. The neutron source used in these calculations was a moderated spectrum from the 9Be(p,n) reaction at a proton energy of 4 MeV. The therapy time to deliver the NCS therapeutic dose of 10000 RBE-cGy, is 27 times longer when 157Gd is used instead of 10B. The skin dose to the treated joint is 33 times larger when 157Gd is used instead of 10B. Furthermore, the impact of using 157Gd instead of 10B was examined in terms of shielded whole-body dose to the patient. The effective dose is 202 mSv for GNCS, compared to 7.6 mSv for BNCS. This is shown to be a result of the longer treatment times required for GNCS; the contribution of the high-energy photons emitted from neutron capture in gadolinium is minimal. Possible explanations as to the relative performance of 157Gd and 10B are discussed, including differences in the RBE and range of boron and gadolinium neutron capture reaction products, and the relative values of the 10B and 157Gd thermal neutron capture cross section as a function of neutron energy. PMID:10947274

  7. Gamma-ray spectra from neutron capture on /sup 87/Sr

    SciTech Connect

    Sullivan, R.E.; Becker, J.A.; Stelts, M.L.

    1981-07-01

    The gamma-ray spectrum following neutron capture on /sup 87/Sr was measured at 3 neutron energies: E/sub n/ = thermal, 2 keV, and 24 keV. Gamma rays were detected in a three-crystal Ge(Li)-NaI-NaI pair spectrometer. Gamma-ray intensities deduced from these spectra by spectral unfolding are presented.

  8. Precision Measurement of Parity Violation in Polarized Cold Neutron Capture on the Proton: the NPDγ Experiment

    NASA Astrophysics Data System (ADS)

    Lauss, Bernhard; Bowman, J. D.; Carlini, R. D.; Chupp, T. E.; Chen, W.; Corvig, S.; Dabaghyan, M.; Desai, D.; Freedman, S. J.; Gentile, T. R.; Gericke, M. T.; Gillis, R. C.; Greene, G. L.; Hersman, F. W.; Ino, T.; Ito, T.; Jones, G. L.; Kandes, M.; Leuschner, M.; Lozowski, B.; Mahurin, R.; Mason, M.; Masuda, Y.; Mei, J.; Mitchell, G. S.; Muto, S.; Nann, H.; Page, S. A.; Penttila, S. I.; Ramsay, W. D.; Santra, S.; Seo, P.-N.; Sharapov, E. I.; Smith, T. B.; Snow, W. M.; Wilburn, W. S.; Yuan, V.; Zhu, H.

    2006-07-01

    The NPDγ experiment at the Los Alamos Neutron Science Center (LANSCE) is dedicated to measure with high precision the parity violating asymmetry in the γ emission after capture of spin polarized cold neutrons in para-hydrogen. The measurement will determine unambiguously the weak pion-nucleon-nucleon (πNN) coupling constant fπ1.

  9. Nominal effective radiation doses delivered during clinical trials of boron neutron capture therapy

    SciTech Connect

    Capala, J.; Diaz, A.Z.; Chanana, A.D.

    1997-12-31

    Boron neutron capture therapy (BNCT) is a binary system that, in theory, should selectively deliver lethal, high linear energy transfer (LET) radiation to tumor cells dispersed within normal tissues. It is based on the nuclear reaction 10-B(n, {alpha})7-Li, which occurs when the stable nucleus of boron-10 captures a thermal neutron. Due to the relatively high cross-section of the 10-B nucleus for thermal neutron capture and short ranges of the products of this reaction, tumor cells in the volume exposed to thermal neutrons and containing sufficiently high concentration of 10-B would receive a much higher radiation dose than the normal cells contained within the exposed volume. Nevertheless, radiation dose deposited in normal tissue by gamma and fast neutron contamination of the neutron beam, as well as neutron capture in nitrogen, 14-N(n,p)14-C, hydrogen, 1-H(n,{gamma})2-H, and in boron present in blood and normal cells, limits the dose that can be delivered to tumor cells. It is, therefore, imperative for the success of the BNCT the dosed delivered to normal tissues be accurately determined in order to optimize the irradiation geometry and to limit the volume of normal tissue exposed to thermal neutrons. These are the major objectives of BNCT treatment planning.

  10. Electron Capture-delayed neutron-emissions in neutron star crust simulations using a Hauser-Feshbach model

    SciTech Connect

    Gupta, Sanjib S.; Heger, A.; Moeller, P.; Kawano, T.

    2008-04-17

    Recently, Electron Captures (henceforth EC) into excited states of neutron-rich nuclei were shown by the LANL-Michigan State-Mainz collaboration to result in Neutron Star (henceforth NS) Crust heating which was 4-5 times that of previous calculations. That result also highlighted the importance of a spread in X-ray burst abundances over several mass chains which could contribute to substantial heating through large shell and sub-shell gaps showing up in the excitation energy spectrum of the EC daughter. Such effects did not dominate when a single beta-stable species was evolved in an accreted parcel of matter in earlier calculations. We are now exploring the nucleosynthesis and heating from neutron processes deeper in the NS Crust around 10{sup 11} gcm{sup -3}. Electron captures into excited states of neutron-rich nuclei above neutron separation energies requires a Hauser-Feshbach code to calculate the branchings between 1-, 2-, 3-,...neutron emission rates in the stellar environment. Since the evolving composition has a free neutron fraction at a very density, the equilibrium composition at a given depth requires readjustments with respect to both the electron chemical potential and the neutron chemical potential, and the emitted neutrons can be captured into other mass chains with a net release of heat. From a nucleosynthesis perspective, we have a very interesting and hitherto unexplored pattern of weak interactions and neutron processes similar to the r-process, with the exception that the weak processes are primarily density-driven in the rather cold crust (T{sub 9} = 0.4-0.6) and in the {beta}{sup +} direction, that is, toward increasing neutron richness.

  11. In-phantom dose mapping in neutron capture therapy by means of solid state detectors

    NASA Astrophysics Data System (ADS)

    Baccaro, S.; Cemmi, A.; Colombi, C.; Fiocca, M.; Gambarini, G.; Lietti, B.; Rosi, G.

    2004-01-01

    A method has been developed, based on thermoluminescent dosimeters and alanine, aimed at measuring the absorbed dose in tissue-equivalent phantoms exposed to an epithermal neutron beam suitable for neutron capture therapy (NCT), separating the contributions due to the various secondary radiations generated by neutrons. Exposures have been made at the TAPIRO nuclear reactor (ENEA, Italy), in the epithermal column properly designed and set up for experiments on boron NCT.

  12. Neutron capture on Gd and Sm in the Luna 16, G-2 soil.

    NASA Technical Reports Server (NTRS)

    Russ, G. P.

    1972-01-01

    Measurement of the Gd and Sm isotopic compositions in the Luna 16, G-2 soil, a sample which has the largest low energy neutron fluence yet observed in a lunar sample. The ratio of the number of neutrons captured per atom by Sm-149 to Gd-157 is 0.76, which is distinct from the value of 0.86 observed at the Apollo 11, 12, and 14 sites. This indicates a softer neutron energy spectrum at the Sea of Plenty.

  13. Measurement of keV-Neutron Capture Gamma Rays for Se Isotopes

    SciTech Connect

    Igashira, Masayuki; Kamada, So; Katabuchi, Tatsuya; Mizumoto, Motoharu

    2009-01-28

    Neutron capture gamma rays were measured for all stable Se isotopes in an incident neutron energy region from 15 to 100 keV. A neutron time-of-flight method was adopted with a ns-pulsed neutron source based on the {sup 7}Li(p,n){sup 7}Be reaction and with a large anti-Compton NaI(Tl) spectrometer. A pulse-height weighting technique was applied to the observed capture gamma-ray pulse-height spectra to obtain the capture yields. Using the standard capture cross sections of {sup 197}Au, the capture cross sections of stable Se isotopes were derived with an error of about 5%. The capture gamma-ray spectra were obtained by unfolding the observed capture gamma-ray pulse-height spectra. The present results for the capture cross sections are compared with the previous measurements and the evaluations of JENDL-3.3 and ENDF/B-VI.8 and VII.0.

  14. Electron exchange and polarization effects on electron captures and neutron emissions by nuclei in white dwarfs and neutron stars

    NASA Astrophysics Data System (ADS)

    Chamel, N.; Fantina, A. F.

    2016-03-01

    In dense stellar environments, nuclei may become unstable against electron captures and/or neutron emissions. These processes are of particular importance for determining the internal constitution of white-dwarf cores and neutron-star crusts. In this paper, the role of electron exchange and polarization effects is studied. In particular, the instability condition for the onset of electron captures and neutron emissions is extended so as to account for electron exchange and polarization. Moreover, general analytical expressions for the corresponding density and pressure are derived. The corrections to the electron-capture threshold in white-dwarf cores are found to be very small. Likewise, the neutron-drip density and pressure in the crusts of accreting and nonaccreting neutron stars are only slightly shifted. Depending on the nuclear mass model employed, electron polarization may change the composition of the crust of nonaccreting neutron stars. On the other hand, the current uncertainties in the masses of neutron-rich Kr and Sr isotopes are found to be more important than electron exchange and polarization effects.

  15. Dose evaluation of boron neutron capture synovectomy using the THOR epithermal neutron beam: a feasibility study

    NASA Astrophysics Data System (ADS)

    Wu, Jay; Chang, Shu-Jun; Chuang, Keh-Shih; Hsueh, Yen-Wan; Yeh, Kuan-Chuan; Wang, Jeng-Ning; Tsai, Wen-Pin

    2007-03-01

    Rheumatoid arthritis is one of the most common epidemic diseases in the world. For some patients, the treatment with steroids or nonsteroidal anti-inflammatory drugs is not effective, thus necessitating physical removal of the inflamed synovium. Alternative approaches other than surgery will provide appropriate disease control and improve the patient's quality of life. In this research, we evaluated the feasibility of conducting boron neutron capture synovectomy (BNCS) with the Tsing Hua open-pool reactor (THOR) as a neutron source. Monte Carlo simulations were performed with arthritic joint models and uncertainties were within 5%. The collimator, reflector and boron concentration were optimized to reduce the treatment time and normal tissue doses. For the knee joint, polyethylene with 40%-enriched Li2CO3 was used as the collimator material, and a rear reflector of 15 cm thick graphite and side reflector of 10 cm thick graphite were chosen. The optimized treatment time was 5.4 min for the parallel-opposed irradiation. For the finger joint, polymethyl methacrylate was used as the reflector material. The treatment time can be reduced to 3.1 min, while skin and bone doses can be effectively reduced by approximately 9% compared with treatment using the graphite reflector. We conclude that using THOR as a treatment modality for BNCS could be a feasible alternative in clinical practice.

  16. Neutron capture cross section of {sup 15}N at stellar energies

    SciTech Connect

    Meissner, J.; Schatz, H.; Herndl, H.; Wiescher, M.; Beer, H.; Kaeppeler, F.

    1996-02-01

    The neutron capture rate on {sup 15}N may be of considerable importance for {ital s}-process nucleosynthesis in red giants as well as for the nucleosynthesis in inhomogeneous big bang scenarios. We measured the reaction cross section of {sup 15}N({ital n},{gamma}){sup 16}N at the Forschungszentrum Karlsruhe with a fast cyclic neutron activation technique at laboratory neutron energies of 25, 152, and 370 keV. Direct capture and shell model calculations were performed to interpret the results. The presented reaction rate is 30{endash}50{percent} smaller than the previously used theoretical rates. {copyright} {ital 1996 The American Physical Society.}

  17. Strong multiple-capture effect in slow Ar17+-Ar collisions: a quantum mechanical analysis

    NASA Astrophysics Data System (ADS)

    Salehzadeh, Arash; Kirchner, Tom

    2013-05-01

    A recent X-ray spectroscopy experiment on 255 keV Ar17+-Ar collisions provided evidence for strong multiple-electron capture. We have coupled a quantum-mechanical independent-electron model calculation for the collision dynamics with (semi-) phenomenological Auger and radiative cascade models to test this finding. The capture calculations are performed using the basis generator method and include single-particle states on the projectile up to the 10th shell. The cross sections obtained for shell-specific multiple capture are fed into an Auger decay scheme in order to obtain n-specific cross sections for apparent single (and double) capture that together with the actual single capture cross sections are then fed into a radiative cascade code. This yields X-ray emission intensities that can be compared with the experimental data of. Good agreement is found for the Lyman series from n = 3 to n = 7 if the multiple-capture contributions are included, whereas calculations that ignore them are in stark conflict with the measurements. This work has been supported by SHARCNET and NSERC Canada.

  18. Non-destructive assay of {sup 242}Pu by resonance neutron capture

    SciTech Connect

    Kane, W.R.; Lu, Ming-Shih; Aronson, A.; Forman, L.; Vanier, P.E.

    1995-08-01

    For the accurate assay of plutonium by neutron correlation measurements, especially for material derived from high-burnup reactor fuel, the content of {sup 242}Pu in a sample must be determined. Since {sup 242}Pu has a long half-life (387,000 yr) and decays to {sup 238}U by alpha particle emission with the accompanying emission of only weak, low-energy gamma rays, gamma-ray spectrometry methods which are ordinarily employed to determine the isotopic composition of a plutonium sample are not feasible for {sup 242}Pu. The existence of a resonance in the neutron capture cross section of {sup 242}Pu at an energy of 2.67 electron volts (eV) with a large (72, 000 barn) cross section affords the possibility for the quantitative assay of this isotope by epithermal neutron capture. Essential for this purpose is an appropriately designed geometry of neutron moderators and absorbers which will provide maximum flux in the eV region while suppressing thermal neutron capture by the fissile plutonium isotopes. Signatures for neutron capture in {sup 242}Pu include the decay of {sup 243}Pu (4.9 hr), prompt capture gamma rays (total energy 5.034 MeV), and the decay of an isomeric state (330 nanosecond). Experiments to determine the feasibility of this approach are currently in progress.

  19. Thermal neutron capture cross section for the K isomer {sup 177}Lu{sup m}

    SciTech Connect

    Belier, G.; Roig, O.; Daugas, J.-M.; Giarmana, O.; Meot, V.; Letourneau, A.; Marie, F.; Foucher, Y.; Aupiais, J.; Abt, D.; Jutier, Ch.; Le Petit, G.; Bettoni, C.; Gaudry, A.; Veyssiere, Ch.; Barat, E.; Dautremer, T.; Trama, J.-Ch.

    2006-01-15

    The thermal neutron radiative capture cross section for the K isomeric state in {sup 177}Lu has been measured for the first time. Several {sup 177}Lu{sup m} targets have been prepared and irradiated in various neutron fluxes at the Lauee Langevin Institute in Grenoble and at the CEA reactors OSIRIS and ORPHEE in Saclay. The method consists of measuring the {sup 178}Lu activity by {gamma}-ray spectroscopy. The values obtained in four different neutron spectra have been used to calculate the resonance integral of the radiative capture cross section for {sup 177}Lu{sup m}. In addition, an indirect method leads to the determination of the {sup 177}Lu{sup g} neutron radiative capture cross section.

  20. Measurement of Neutron Capture Cross Section of 62Ni in the keV-Region

    SciTech Connect

    Alpizar-Vicente, A. M.; Hatarik, R.; Bredeweg, T. A.; Esch, E.-I.; Haight, R. C.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Greife, U.

    2006-03-13

    The neutron capture cross section of 62Ni, relative to gold as a standard, was determined in the energy range from 250 eV to 100 keV. This energy range covers the region between 5 keV to 20 keV, which is not available in ENDF. Capture events are detected with the 160-fold 4{pi} BaF2 Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center. One of the challenges was to process the high count rate of 4 MHz, which required an optimization of the data acquisition software. The neutron energy was determined by the time-of-flight technique using a flight path of 20.25 m. The sample mass of the 96% enriched 62Ni target was 210 mg and it was mounted in a 1.5 {mu}m thick Mylar foil.

  1. Gamma-Ray Strength Function Method:. Away from Photoneutron Emission to Radiative Neutron Capture

    NASA Astrophysics Data System (ADS)

    Utsunomiya, H.; Akimune, H.; Yamagata, T.; Iwamoto, C.; Goriely, S.; Daoutidis, I.; Toyokawa, H.; Harada, H.; Kitatani, F.; Iwamoto, N.; Lui, Y. W.; Arteaga, D. P.; Hilaire, S.; Koning, A. J.

    2013-03-01

    Radiative neutron capture cross sections are of direct relevance for the synthesis of heavy elements referred to as the s-process and the r-process in nuclear astrophysics and constitute basic data in the field of nuclear engineering. The surrogate reaction technique is in active use to indirectly determine radiative neutron capture cross sections for unstable nuclei. We have devised an indirect method alternative to the surrogate reaction technique on the basis of the ?-ray strength function (?SF), a nuclear statistical quantity that interconnects photoneutron emission and radiative neutron capture in the Hauser-Feshbach model calculation. We outline the ?SF method and show applications of the method to tin, palladium, and zirconium isotopes. In the application of the ?SF method, it is important to use ?SF's that incorporate extra strengths of PDR and/or M1 resonance emerging around neutron threshold.

  2. Characterization of a 10B-doped liquid scintillator as a capture-gated neutron spectrometer

    NASA Astrophysics Data System (ADS)

    Hunt, S.; Iliadis, C.; Longland, R.

    2016-03-01

    We use a 250 MHz digitizer to characterize the pulse shape discrimination of a BC-523A 10B-doped liquid scintillator with capture-gating capabilities. Our results are compared to recent work claiming pulse shape discrimination between fast and thermal neutron signals. The capture event is identified, and we explain the origin of signals that are often misinterpreted. We use the time-of-flight method to measure the detector energy resolution for fast incident monoenergetic neutrons and the intrinsic neutron detection efficiency. Monte Carlo simulations are performed and we find agreement between measured and simulated results. These steps are important for understanding 10B-doped capture-gated spectroscopy in mixed radiation environments, as efficiencies using capture-gating are rarely reported in the literature.

  3. Measurements of neutron capture cross section for {sup 207,208}Pb

    SciTech Connect

    Segawa, M.; Toh, Y.; Harada, H.; Kitatani, F.; Koizumi, M.; Fukahori, T.; Iwamoto, N.; Iwamoto, O.; Oshima, M.; Hatsukawa, Y.; Nagai, Y.; Igashira, M.; Kamada, S.; Tajika, M.

    2014-05-02

    The neutron capture cross sections for {sup 207,208}Pb have been measured in the neutron energy region from 10 to 110 keV. The γ-rays cascaded from a capture state to the ground state or low-lying states of {sup 208,209}Pb were observed for the first time, using an anti-Compton Nal(Tl) spectrometer and a TOF method. The observed discrete γ-ray energy spectra enabled us to determine neutron capture cross sections for {sup 207,208}Pb with small systematic errors, since we could distinguish γ-ray of {sup 207,208}Pb(n,γ) reactions from background γ-ray with use of the γ-ray spectra. The obtained cross sections include both contributions of resonance and direct capture components different from the previous TOF measurements.

  4. Measurement of the keV-neutron capture cross section and capture gamma-ray spectrum of isotopes around N=82 region

    SciTech Connect

    Katabuchi, Tatsuya; Igashira, Masayuki

    2012-11-12

    The keV-neutron capture cross section and capture {gamma}-ray spectra of nuclides with a neutron magic number N= 82, {sup 139}La and {sup 142}Nd, were newly measured by the time-of-flight method. Capture {gamma}-rays were detected with an anti-Compton NaI(T1) spectrometer, and the pulse-height weighting technique was applied to derive the neutron capture cross section. The results were provided with our previous measurements of other nuclides around N= 82, {sup 140}Ce, {sup 141}Pr, {sup 143}Nd and {sup 145}Nd.

  5. New Methods for the Determination of Total Radiative Thermal Neutron Capture Cross Sections

    SciTech Connect

    Firestone, R. B.; Krticka, M.; McNabb, D. P.; Sleaford, B.; Agvaanluvsan, U.; Belgya, T.; Revay, Zs.

    2008-04-17

    Precise gamma-ray thermal neutron capture cross sections have been measured at the Budapest Reactor for all elements with Z = 1-83,92 except for He and Pm. These measurements and additional data from the literature been compiled to generate the Evaluated Gamma-ray Activation File (EGAF), which is disseminated by LBNL and the IAEA. These data are nearly complete for most isotopes with Z<20 so the total radiative thermal neutron capture cross sections can be determined directly from the decay scheme. For light isotopes agreement with the recommended values is generally satisfactory although large discrepancies exist for {sup 11}B, {sup 12,13}C, {sup 15}N, {sup 28,30}Si, {sup 34}S, {sup 37}Cl, and {sup 40,41}K. Neutron capture decay data for heavier isotopes are typically incomplete due to the contribution of unresolved continuum transitions so only partial radiative thermal neutron capture cross sections can be determined. The contribution of the continuum to the neutron capture decay scheme arises from a large number of unresolved levels and transitions and can be calculated by assuming that the fluctuations in level densities and transition probabilities are statistical. We have calculated the continuum contribution to neutron capture decay for the palladium isotopes with the Monte Carlo code DICEBOX. These calculations were normalized to the experimental cross sections deexciting low excitation levels to determine the total radiative thermal neutron capture cross section. The resulting palladium cross sections values were determined with a precision comparable to the recommended values even when only one gamma-ray cross section was measured. The calculated and experimental level feedings could also be compared to determine spin and parity assignments for low-lying levels.

  6. Measurement of Gamma Rays from keV-Neutron Capture Reaction by Zr-90, 94

    SciTech Connect

    Ohgama, Kazuya; Igashira, Masayuki; Ohsaki, Toshiro

    2006-03-13

    The {gamma} rays from the neutron capture reaction by 90,94Zr were measured in an incident neutron energy region from 15 to 100 keV and at 550 keV. A neutron time-of-flight method was adopted with a 1.5-ns pulsed neutron source by the 7Li(p,n)7Be reaction and with a large anti-Compton NaI(Tl) spectrometer. A pulse-height weighting technique was applied to observed capture {gamma}-ray pulse-height spectra to derive capture yields. Using the standard capture cross sections of 197Au in ENDF/B-VI, the capture cross sections of 90, 94Zr were obtained with the errors from 6 to 8%. The present results were compared with previous measurements and the evaluations of JENDL-3.3 and ENDF/B-VI. The capture {gamma}-ray spectra of 90, 94Zr were obtained by unfolding the observed capture {gamma}-ray pulse-height spectra. The multiplicities of observed {gamma} rays were derived from the {gamma}-ray spectra.

  7. Chandra Captures Neutron Star Action - Duration: 61 seconds.

    NASA Video Gallery

    This movie from NASA's Chandra X-ray Observatory shows a fast moving jet of particles produced by a rapidly rotating neutron star, and may provide new insight into the nature of some of the densest...

  8. Study on the keV neutron capture reaction in 56Fe and 57Fe

    NASA Astrophysics Data System (ADS)

    Wang, Taofeng; Lee, Manwoo; Kim, Guinyun; Ro, Tae-Ik; Kang, Yeong-Rok; Igashira, Masayuki; Katabuchi, Tatsuya

    2014-03-01

    The neutron capture cross-sections and the radiative capture gamma-ray spectra from the broad resonances of 56Fe and 57Fe in the neutron energy range from 10 to 90keV and 550keV have been measured with an anti-Compton NaI(Tl) detector. Pulsed keV neutrons were produced from the 7Li 7Be reaction by bombarding the lithium target with the 1.5ns bunched proton beam from the 3MV Pelletron accelerator. The incident neutron spectrum on a capture sample was measured by means of a time-of-flight (TOF) method with a 6Li -glass detector. The number of weighted capture counts of the iron or gold sample was obtained by applying a pulse height weighting technique to the corresponding capture gamma-ray pulse height spectrum. The neutron capture gamma-ray spectra were obtained by unfolding the observed capture gamma-ray pulse height spectra. To achieve further understanding on the mechanism of neutron radiative capture reaction and study on physics models, theoretical calculations of the -ray spectra for 56Fe and 57Fe with the POD program have been performed by applying the Hauser-Feshbach statistical model. The dominant ingredients to perform the statistical calculation were the Optical Model Potential (OMP), the level densities described by the Mengoni-Nakajima approach, and the -ray transmission coefficients described by -ray strength functions. The comparison of the theoretical calculations, performed only for the 550keV point, show a good agreement with the present experimental results.

  9. A study on the optimum fast neutron flux for boron neutron capture therapy of deep-seated tumors.

    PubMed

    Rasouli, Fatemeh S; Masoudi, S Farhad

    2015-02-01

    High-energy neutrons, named fast neutrons which have a number of undesirable biological effects on tissue, are a challenging problem in beam designing for Boron Neutron Capture Therapy, BNCT. In spite of this fact, there is not a widely accepted criterion to guide the beam designer to determine the appropriate contribution of fast neutrons in the spectrum. Although a number of researchers have proposed a target value for the ratio of fast neutron flux to epithermal neutron flux, it can be shown that this criterion may not provide the optimum treatment condition. This simulation study deals with the determination of the optimum contribution of fast neutron flux in the beam for BNCT of deep-seated tumors. Since the dose due to these high-energy neutrons damages shallow tissues, delivered dose to skin is considered as a measure for determining the acceptability of the designed beam. To serve this purpose, various beam shaping assemblies that result in different contribution of fast neutron flux are designed. The performances of the neutron beams corresponding to such configurations are assessed in a simulated head phantom. It is shown that the previously used criterion, which suggests a limit value for the contribution of fast neutrons in beam, does not necessarily provide the optimum condition. Accordingly, it is important to specify other complementary limits considering the energy of fast neutrons. By analyzing various neutron spectra, two limits on fast neutron flux are proposed and their validity is investigated. The results show that considering these limits together with the widely accepted IAEA criteria makes it possible to have a more realistic assessment of sufficiency of the designed beam. Satisfying these criteria not only leads to reduction of delivered dose to skin, but also increases the advantage depth in tissue and delivered dose to tumor during the treatment time. The Monte Carlo Code, MCNP-X, is used to perform these simulations. PMID:25479433

  10. Investigation of the Statistical Properties of Stable Eu Nuclei using Neutron-Capture Reactions

    SciTech Connect

    Agvaanluvsan, U; Alpizar-Vicente, A; Becker, J A; Becvar, F; Bredeweg, T A; Clement, R; Esch, E; Folden, III, C M; Hatarik, R; Haight, R C; Hoffman, D C; Krticka, M; Macri, R A; Mitchell, G E; Nitsche, H; O'Donnell, J M; Parker, W; Reifarth, R; Rundberg, R S; Schwantes, J M; Sheets, S A; Ullmann, J L; Vieira, D J; Wilhelmy, J B; Wilk, P; Wouters, J M; Wu, C Y

    2005-10-04

    Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for {sup 151,153}Eu targets. The highly efficient DANCE (Detector for Advanced Neutron Capture Experiments) array coupled with the intense neutron beam at Los Alamos Neutron Science Center is used for the experiment. Stable Eu isotopes mass separated and electroplated on Be backings were used. Properties of well-resolved, strong resonances in two Eu nuclei are examined. The parameters for most of these resonances are known. Detailed multiplicity information for each resonance is obtained employing the high granularity of the DANCE array. The radiative decay cascades corresponding to each resonance are obtained in the experiment. The measurements are compared to simulation of these cascades which calculated with various models for the radiative strength function. Comparison between the experimental data and simulation provides an opportunity to investigate the average quantities.

  11. Neutron-pair transfer in the sub-barrier capture process

    NASA Astrophysics Data System (ADS)

    Sargsyan, V. V.; Scamps, G.; Adamian, G. G.; Antonenko, N. V.; Lacroix, D.

    2013-12-01

    Sub-barrier capture reactions following neutron-pair transfer are proposed to be used for the indirect study of the neutron-neutron correlation in the surface region of a nucleus. The strong effect of dineutron-like cluster transfer stemming from the surface of magic and nonmagic nuclei 18O, 48Ca, 64Ni, 94,96Mo, 100,102,104Ru, 104,106,108Pd, and 112,114,116,118,120,124,132Sn is demonstrated. The dominance of the two-neutron transfer channel in the vicinity of the Coulomb barrier is further supported by time-dependent mean-field approaches.

  12. FY07 LDRD Final Report Neutron Capture Cross-Section Measurements at DANCE

    SciTech Connect

    Parker, W; Agvaanluvsan, U; Wilk, P; Becker, J; Wang, T

    2008-02-08

    We have measured neutron capture cross sections intended to address defense science problems including mix and the Quantification of Margins and Uncertainties (QMU), and provide details about statistical decay of excited nuclei. A major part of this project included developing the ability to produce radioactive targets. The cross-section measurements were made using the white neutron source at the Los Alamos Neutron Science Center, the detector array called DANCE (The Detector for Advanced Neutron Capture Experiments) and targets important for astrophysics and stockpile stewardship. DANCE is at the leading edge of neutron capture physics and represents a major leap forward in capability. The detector array was recently built with LDRD money. Our measurements are a significant part of the early results from the new experimental DANCE facility. Neutron capture reactions are important for basic nuclear science, including astrophysics and the statistics of the {gamma}-ray cascades, and for applied science, including stockpile science and technology. We were most interested in neutron capture with neutron energies in the range between 1 eV and a few hundred keV, with targets important to basic science, and the s-process in particular. Of particular interest were neutron capture cross-section measurements of rare isotopes, especially radioactive isotopes. A strong collaboration between universities and Los Alamos due to the Academic Alliance was in place at the start of our project. Our project gave Livermore leverage in focusing on Livermore interests. The Lawrence Livermore Laboratory did not have a resident expert in cross-section measurements; this project allowed us to develop this expertise. For many radionuclides, the cross sections for destruction, especially (n,{gamma}), are not well known, and there is no adequate model that describes neutron capture. The modeling problem is significant because, at low energies where capture reactions are important, the neutron reaction cross sections show resonance behavior or follow 1/v of the incident neutrons. In the case of odd-odd nuclei, the modeling problem is particularly difficult because degenerate states (rotational bands) present in even-even nuclei have separated in energy. Our work included interpretation of the {gamma}-ray spectra to compare with the Statistical Model and provides information on level density and statistical decay. Neutron capture cross sections are of programmatic interest to defense sciences because many elements were added to nuclear devices in order to determine various details of the nuclear detonation, including fission yields, fusion yields, and mix. Both product nuclei created by (n,2n) reactions and reactant nuclei are transmuted by neutron capture during the explosion. Very few of the (n,{gamma}) cross sections for reactions that create products measured by radiochemists have ever been experimentally determined; most are calculated by radiochemical equivalences. Our new experimentally measured capture cross sections directly impact our knowledge about the uncertainties in device performances, which enhances our capability of carrying out our stockpile stewardship program. Europium and gadolinium cross sections are important for both astrophysics and defense programs. Measurements made prior to this project on stable europium targets differ by 30-40%, which was considered to be significantly disparate. Of the gadolinium isotopes, {sup 151}Gd is important for stockpile stewardship, and {sup 153}Gd is of high interest to astrophysics, and nether of these (radioactive) gadolinium (n,{gamma}) cross sections have been measured. Additional stable gadolinium isotopes, including {sup 157,160}Gd are of interest to astrophysics. Historical measurements of gadolinium isotopes, including {sup 152,154}Gd, had disagreements similar to the 30-40% disagreements found in the historical europium data. Actinide capture cross section measurements are important for both Stockpile Stewardship and for nuclear forensics. We focused on the {sup 242m}Am(n,{gamma}) mea

  13. IMPROVED COMPUTATIONAL CHARACTERIZATION OF THE THERMAL NEUTRON SOURCE FOR NEUTRON CAPTURE THERAPY RESEARCH AT THE UNIVERSITY OF MISSOURI

    SciTech Connect

    Stuart R. Slattery; David W. Nigg; John D. Brockman; M. Frederick Hawthorne

    2010-05-01

    Parameter studies, design calculations and initial neutronic performance measurements have been completed for a new thermal neutron beamline to be used for neutron capture therapy cell and small-animal radiobiology studies at the University of Missouri Research Reactor. The beamline features the use of single-crystal silicon and bismuth sections for neutron filtering and for reduction of incident gamma radiation. The computational models used for the final beam design and performance evaluation are based on coupled discrete-ordinates and Monte Carlo techniques that permit detailed modeling of the neutron transmission properties of the filtering crystals with very few approximations. This is essential for detailed dosimetric studies required for the anticipated research program.

  14. A new MCNPX PTRAC coincidence capture file capability: a tool for neutron detector design

    SciTech Connect

    Evans, Louise G; Schear, Melissa A; Hendricks, John S; Swinhoe, Martyn T; Tobin, Stephen J; Croft, Stephen

    2010-12-14

    The existing MCNPX{trademark} PTRAC coincidence capture file allows a full list of neutron capture events to be recorded in any simulated detection medium. The originating event history number (e.g. spontaneous fission events), capture time, location and source particle number are tracked and output to file for post-processing. We have developed a new MCNPX PTRAC coincidence capture file capability to aid detector design studies. New features include the ability to track the isotopes that emitted the detected neutrons as well as induced fission chains in mixed samples before detection (both generation number and isotope). Here, the power of this tool is demonstrated using a detector design that has been developed for the non-destructive assay (NDA) of spent nuclear fuel. Individual capture time distributions have been generated for neutrons originating from Curium-244 source spontaneous fission events and induced fission events in fissile isotopes of interest: namely Plutonium-239, Plutonium-241, and Uranium-235. Through this capability, a full picture for the attribution of neutron capture events in the detector can be simulated.

  15. (A clinical trial of neutron capture therapy for brain tumors)

    SciTech Connect

    Zamenhof, R.G.

    1989-01-01

    This report describes accomplishments by this laboratory concerning development of high-resolution alpha-autoradiography design of an optimized epithermal neutron beam dosimetry and treatment planning Using Monte Carlo techniques development of a prompt-gamma {sup 10}B analysis facility.

  16. (A clinical trial of neutron capture therapy for brain tumors)

    SciTech Connect

    Zamenhof, R.G.

    1990-01-01

    This document briefly describes recent advances in the author's laboratory. Topics described include neutron beam design, high- resolution autoradiography, boronated phenylalanine (BPA) distribution and survival studies in glioma bearing mice, computer- aided treatment planning, prompt gamma boron 10 analysis facility at MITI-II, non-rodent BPA toxicity studies, and preparations for clinical studies.

  17. Using the TREAT reactor in support of boron neutron capture therapy (BNCT) experiments: A feasibility analysis

    SciTech Connect

    Grasseschi, G.L.; Schaefer, R.W.

    1996-03-01

    The technical feasibility of using the TREAT reactor facility for boron neutron capture therapy (BNCT) research was assessed. Using one-dimensional neutronics calculations, it was shown that the TREAT core neutron spectrum can be filtered to reduce the undesired radiation (contamination) dose per desired neutron more effectively than can the core spectra from two prominent candidate reactors. Using two-dimensional calculations, it was demonstrated that a non-optimized filter replacing the TREAT thermal column can yield a fluence of desired-energy neutrons more than twice as large as the fluence believed to be required and, at the same time, have a contamination dose per desired neutron almost as low as that from any other candidate facility. The time, effort and cost required to adapt TREAT for a mission supporting BNCT research would be modest.

  18. Estimates for Pu-239 loadings in burial ground culverts based on fast/slow neutron measurements

    SciTech Connect

    Winn, W.G.; Hochel, R.C.; Hofstetter, K.J.; Sigg, R.A.

    1989-08-15

    This report provides guideline estimates for Pu-239 mass loadings in selected burial ground culverts. The relatively high recorded Pu-239 contents of these culverts have been appraised as suspect relative to criticality concerns, because they were assayed only with the solid waste monitor (SWM) per gamma-ray counting. After 1985, subsequent waste was also assayed with the neutron coincidence counter (NCC), and a comparison of the assay methods showed that the NCC generally yielded higher assays than the SWM. These higher NCC readings signaled a need to conduct non-destructive/non-intrusive nuclear interrogations of these culverts, and a technical team conducted scoping measurements to illustrate potential assay methods based on neutron and/or gamma counting. A fast/slow neutron method has been developed to estimate the Pu-239 in the culverts. In addition, loading records include the SWM assays of all Pu-239 cuts of some of the culvert drums and these data are useful in estimating the corresponding NCC drum assays from NCC vs SWM data. Together, these methods yield predictions based on direct measurements and statistical inference.

  19. Review of measurement techniques for the neutron radiative-capture process

    SciTech Connect

    Poenitz, W.P.

    1981-07-01

    The experimental techniques applied in measurements of the neutron capture process are reviewed. The emphasis is on measurement techniques used in neutron capture cross section measurements. The activation technique applied mainly in earlier work has still its use in some cases, specifically for measurements of technologically important cross sections (/sup 238/U and /sup 232/Th) with high accuracy. Three major prompt neutron radioactive capture detection techniques have evolved: the total gamma radiation energy detection technique (mainly with large liquid scintillation detectors), the gamma-energy proportional detectors (with proportional counters or Moxon-Rae detectors), and the pulse-height weighting technique. These measurement techniques are generally applicable, however, shortcomings limit the achievable accuracy to a approx. = 5 to 15% uncertainty level.

  20. Role of neutron transfer in capture processes at sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.; Scheid, W.; Zhang, H. Q.

    2012-02-01

    The role of neutron transfer with positive Q-value in sub-barrier capture reactions 132Sn,130Te+58,64Ni, and 60Ni+100Mo, measured recently by Z. Kohley [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.202701 107, 202701 (2011)] and F. Scarlassara [EPJ Web Conf.2100-014X10.1051/epjconf/20111705002 17, 05002 (2011)], is studied and explained within the quantum diffusion approach. It is shown that the transfer of two neutrons influences the sub-barrier capture through the change of the deformations of the colliding nuclei. Based on our analysis, one can understand why the influence of the neutron transfer is strong in some capture reactions, but is weak in others.

  1. Synthesis of carboranylthiouracils for neutron capture therapy of malignant melanoma

    SciTech Connect

    Wilson, J.G.

    1994-06-22

    1,2-closo-dodecaboranes synthesized from alkynyl-substituted thiouracils are potentially useful as boron neutral capture therapy agents. This work describes the synthesis, purification, and characterization of these compounds. NMR and IR spectroscopies were used to structurally characterize the products.

  2. Population Signatures in Planetary Nebulae from Abundances of Fe-group and Neutron-Capture Elements

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet L.; Geballe, Thomas R.; Sterling, N. C.

    2015-08-01

    There are two categories of elements for which abundances are measured in planetary nebulae (PNe). The first are species whose abundances may be modified by nuclear reactions in the star prior to PN formation, such as He, C, N, and nuclei made by slow neutron captures (Karakas & Lattanzio 2014, PASA, 31, 30). In contrast, elements unaffected by evolution should indicate the star’s initial composition. These include S, Ar, Cl, and (with certain exceptions) O and Ne, most of which are alpha species. A long-missing piece of the puzzle has been the abundances of the Fe-group elements. We cannot determine a meaningful elemental abundance from the gas-phase Fe lines seen in PNe, since Fe is heavily depleted into dust. Another approach is to use a different element as a proxy for Fe. Dinerstein & Geballe (2001, ApJ, 562, 515) identified a line at 3.625 μm as due to Zn, the least refractory Fe-group element. Observations of this line in Milky Way PNe yield -1 ≤ [Zn/H] ≤ 0 (Smith, Zijlstra, & Dinerstein 2014, MNRAS, 441, 3161; Dinerstein et al. 2015, in preparation). Substituting Zn for Fe, PNe can be placed in the [alpha/Fe] vs. [Fe/H] diagram used to characterize stellar populations. Dividing our sample into probable thin and thick disk members using the kinematic criterion of Peimbert’s Type II and III classes (1978, IAU Symp. 76, 215), we find that they occupy similar regions in [alpha/Fe] vs. [Fe/H] phase space as the stars of those populations. Elevated [alpha/Fe] values at subsolar [Fe/H], which tend to be higher for thick than thin disk PNe, cause degeneracies that make alpha species ambiguous metallicity indicators. This is important for self-enrichment studies, since if the initial abundance of an element is lower than projected from an alpha species, internal synthesis may be required to produce even a solar final abundance. Low observed abundances of the n-capture element Se suggest that many Type III PNe may have subsolar initial abundances of n-capture elements (Sterling, Porter, & Dinerstein 2015, submitted). This work was supported by NSF grants AST-0708429 and 0901432, and JPL contract 1427884.

  3. Deep Optical Spectroscopy of Planetary Nebulae: The Search for Neutron-Capture Elements

    NASA Astrophysics Data System (ADS)

    Sterling, Nicholas C.; Garofali, K.; Dinerstein, H. L.; Hwang, S.; Redfield, S.

    2013-01-01

    We present deep, high-resolution (R=36,700) optical spectra of five planetary nebulae (PNe), taken with the 2D-coude echelle spectrograph on the 2.7-m Harlan J. Smith Telescope at McDonald Observatory. These observations are part of a larger optical survey of PNe, designed to unambiguously detect emission lines from neutron(n)-capture elements (atomic number Z>30). The abundances of these elements are of particular interest in PNe, since they can be produced by slow n-capture nucleosynthesis (the ``s-process'') during the asymptotic giant branch (AGB) stage of evolution of PN progenitor stars. The first large-scale investigation of n-capture element abundances in PNe (Sterling & Dinerstein 2008, ApJS, 174, 157) surveyed [Kr III] and [Se IV] transitions in the K band spectra of more than 80 PNe. However, the abundances derived from these data relied on ionization corrections that were often large and uncertain due to the detection of only one ion per element. Transitions of other Se and Kr ions, as well as many other trans-iron species, reside at optical wavelengths. High-resolution spectra are essential to unequivocally identify these lines and resolve potential blends with other species. The spectra we present are rich in emission features, with between 125 and 600 distinct lines detected in each PN. Emission from at least one Kr ion is detected in all five objects, and two (Hb 12 and J 900) exhibit emission from multiple Kr ions. We detected multiple Xe ions in J 900, as well as Se, Br, and Rb lines. Hb 12 also exhibits Xe emission, and the first detection of [Se II] in a PN to our knowledge. The spectra display a wealth of other emission lines, including permitted features of second-row elements and forbidden transitions of several iron-peak elements (e.g., Cr, Mn, Fe, Co, Ni, and Cu). Our survey makes it possible to derive more accurate Se and Kr abundances in PNe, and reveals the enrichment of other trans-iron elements. This enables more accurate s-process enrichment factors to be derived for PNe, providing important constraints to models of AGB nucleosynthesis and the chemical evolution of trans-iron nuclides. This research was supported by NSF awards AST-0708425 and AST-901432.

  4. Neutron capture effects in lunar gadolinium and the irradiation histories of some lunar rocks.

    NASA Technical Reports Server (NTRS)

    Lugmair, G. W.; Marti, K.

    1971-01-01

    The Gd isotopic composition in 19 lunar rock and soil samples from three Apollo sites is reported. The analytical techniques and the high precision mass spectrometric measurements are discussed. Enrichments in the Gd-158 oxide to G-157 oxide ratio due to neutron capture range up to 0.75%. Integrated 'thermal' neutron fluxes derived from the isotopic anomalies of Gd are compared with spallation Kr data from aliquot samples to construct a model which gives both average cosmic-ray irradiation depths and effective neutron exposure ages for some rocks. Rock 14310 is the first lunar sample where Kr anomalies due to resonance neutron capture in Br are observed. A Kr-81/Kr exposure age of 262 (plus or minus 7)m.y. is calculated for this rock.

  5. Early clinical experience of boron neutron capture therapy for glioblastoma multiforme

    SciTech Connect

    Joel, D.D.; Bergland, R.; Capala, J.

    1995-12-31

    Boron neutron capture therapy (BNCT) is a binary treatment modality that can selectively irradiate tumor tissue. BNCT uses drugs containing a stable isotope of boron. {sup 10}B, to sensitize tumor cells to irradiation by low energy (thermal) neutrons. The interaction of the {sup 10}B with a thermal neutron (neutron capture) causes the {sup 10}B nucleus to split, releasing an alpha particle and a lithium nucleus. These products of the {sup 10}B(n, {alpha}){sup 7}Li reaction are very damaging to cells but have a combined path length in tissue of approximately 14 {mu}m, or roughly the diameter of one or two cells. Thus, most of the ionizing energy imparted to tissue is localized to {sup 10}B-loaded cells.

  6. Experimental neutron capture data of 58Ni from the CERN n_TOF facility

    NASA Astrophysics Data System (ADS)

    Žugec, P.; Barbagallo, M.; Colonna, N.; Bosnar, D.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Duran, I.; Dzysiuk, N.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A. R.; Giubrone, G.; Gómez-Hornillos, M. B.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Gurusamy, P.; Heinitz, S.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Kokkoris, M.; Krtička, M.; Kroll, J.; Langer, C.; Lederer, C.; Leeb, H.; Leong, L. S.; Lo Meo, S.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P. F.; Mastromarco, M.; Meaze, M.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondalaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Pignatari, M.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riegov, A.; Roman, F.; Rubbia, C.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J. L.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T.

    2015-05-01

    The neutron capture cross section of 58Ni was measured at the neutron time of flight facility n_TOF at CERN, from 27 meV to 400 keV neutron energy. Special care has been taken to identify all the possible sources of background, with the so-called neutron background obtained for the first time using high-precision GEANT4 simulations. The energy range up to 122 keV was treated as the resolved resonance region, where 51 resonances were identified and analyzed by a multilevel R-matrix code SAMMY. Above 122 keV the code SESH was used in analyzing the unresolved resonance region of the capture yield. Maxwellian averaged cross sections were calculated in the temperature range of kT = 5 - 100 keV, and their astrophysical implications were investigated.

  7. Neutron-capture experiment on 77Se with EXILL at ILL Grenoble

    NASA Astrophysics Data System (ADS)

    Lorenz, Ch.; John, R.; Massarczyk, R.; Schwengner, R.; Blanc, A.; de France, G.; Jentschel, M.; Köster, U.; Mutti, P.; Simpson, G.; Soldner, T.; Urban, W.; Valenta, S.; Belgya, T.

    2015-05-01

    The neutron capture reaction at 77Se has been studied with cold neutrons in the course of the EXILL campaign at the high-flux reactor of the Institut Laue-Langevin Grenoble. A simulation of the detector array with Geant4 has been accomplished and evaluated. The detector response has been deduced and measured spectra were unfolded, which have been compared with simulations using γDex to determine strength functions.

  8. Power Burst Facility/Boron Neutron Capture Therapy Program for cancer treatment

    SciTech Connect

    Ackermann, A.L.; Dorn, R.V. III.

    1990-08-01

    This report discusses monthly progress in the Power Boron Facility/Boron Neutron Capture Therapy (PBF/BNCT) Program for Cancer Treatment. Highlights of the PBF/BNCT Program during August 1990 include progress within the areas of: Gross Boron Analysis in Tissue, Blood, and Urine, boron microscopic (subcellular) analytical development, noninvasive boron quantitative determination, analytical radiation transport and interaction modeling for BNCT, large animal model studies, neutron source and facility preparation, administration and common support and PBF operations.

  9. Improvement of depth dose distribution using multiple-field irradiation in boron neutron capture therapy.

    PubMed

    Fujimoto, N; Tanaka, H; Sakurai, Y; Takata, T; Kondo, N; Narabayashi, M; Nakagawa, Y; Watanabe, T; Kinashi, Y; Masunaga, S; Maruhashi, A; Ono, K; Suzuki, M

    2015-12-01

    It is important that improvements are made to depth dose distribution in boron neutron capture therapy, because the neutrons do not reach the innermost regions of the human body. Here, we evaluated the dose distribution obtained using multiple-field irradiation in simulation. From a dose volume histogram analysis, it was found that the mean and minimum tumor doses were increased using two-field irradiation, because of improved dose distribution for deeper-sited tumors. PMID:26282566

  10. Power Burst Facility/Boron Neutron Capture Therapy program for cancer treatment, Volume 4, No. 7

    SciTech Connect

    Ackermann, A.L.

    1990-07-01

    This report discusses the monthly progress of the Power Burst Facility/Boron Neutron Capture Therapy (PBF/BNLT) program for cancer treatment. Highlights of the PBF/BNCT Program during July 1990 include progress within the areas of: Gross boron analysis in tissue, blood, and urine; noninvasive boron quantitative determination; analytical radiation transport and interaction modeling for BNCT; large animal model studies; neutron source and facility preparation; administration and common support and PBF operations.

  11. Neutron emission following muon capture in Ce-142, Ce-140, Ba-138, and Sn-120.

    NASA Technical Reports Server (NTRS)

    Lucas, G. R., Jr.; Martin, P.; Welsh, R. E.; Jenkins, D. A.; Powers, R. J.; Kunselman, A. R.; Miller, G. H.

    1973-01-01

    Branching ratios to excited nuclear states formed after muon capture have been measured with Ge(Li) detectors. The delayed gamma rays were observed in studies of muonic Ce-142, Ce-140, Ba-138, and Sn-120, using separated isotopes. The resulting isotopes formed indicate at least a 60% probability of neutron emission upon muon capture, with the most likely product resulting from single-neutron emission. No evidence for delayed proton emission with a probability higher than 2% was found. Using our more precise energies for the observed nuclear transitions, we present revised energy levels schemes for La-141, La-139, Cs-137, and In-119.

  12. {sup 33}S for Neutron Capture Therapy: Nuclear Data for Monte Carlo Calculations

    SciTech Connect

    Porras, I.; Sabat-Gilarte, M.; Praena, J.; Quesada, J.M.; Esquinas, P.L.

    2014-06-15

    A study of the nuclear data required for the Monte Carlo simulation of boron neutron capture therapy including the {sup 33}S isotope as an enhancer of the dose at small depths has been performed. In particular, the controversy on the available data for the {sup 33}S(n, ?) cross section will be shown, which motivates new measurements. In addition to this, kerma factors for the main components of tissue are calculated with the use of fitting functions. Finally, we have applied these data to a potential neutron capture treatment with boron and sulfur addition to tissue in which part of the hydrogen atoms are replaced by deuterium, which improves the procedure.

  13. Effects of soil moisture on the detection of buried explosives by radiative neutron capture

    NASA Astrophysics Data System (ADS)

    Pesente, S.; Cinausero, M.; Fabris, D.; Fioretto, E.; Lunardon, M.; Nebbia, G.; Prete, G.; Viesti, G.

    2001-03-01

    The effect of soil moisture on the sensitivity for detecting buried landmines by neutron capture reactions has been experimentally investigated. An explosive simulant melamine sample has been placed at different depths in soil having different water contents. In dry soil it is found that the decrease of counting rate by increasing the depth follows the decrease of the average solid angles. In the case of soil with higher water content, an extra yield of prompt gamma-rays following thermal neutron capture in nitrogen is evidenced due to the extra moderation provided by the presence of additional hydrogen nuclei.

  14. Neutron Capture on 130Sn during r-Process Freeze-Out

    SciTech Connect

    Beun, Joshua; Blackmon, Jeffery C; Hix, William Raphael; Mclaughlin, Gail C; Smith, Michael Scott; Surman, Rebecca

    2009-01-01

    We examine the role of neutron capture on {sup 130}Sn during r-process freeze-out in the neutrino-driven wind environment of the core-collapse supernova. We find that the global r-process abundance pattern is sensitive to the magnitude of the neutron capture cross section of {sup 130}Sn. The changes to the abundance pattern include not only a relative decrease in the abundance of {sup 130}Sn and an increase in the abundance of {sup 131}Sn, but also a shift in the distribution of material in the rare earth and third peak regions.

  15. Measurements of Thermal Neutron Capture Cross Sections of 136Ce, 156Dy, and 168Yb

    NASA Astrophysics Data System (ADS)

    Lee, J. Y.; Kim, Y. D.; Sun, G. M.

    2014-05-01

    For several low abundance stable nuclei, the thermal neutron capture cross sections are not well measured, while the cross sections for isotopes with high abundances are already well measured. Our experiments, different from the commonly used method of using gold foil as reference, are performed using natural foils for which we know the relative abundances of all isotopes and thermal neutron capture cross sections. Therefore, we can obtain the cross sections of low abundance isotopes, which are not known well, by comparing the yields of gammas from the neutron captures by various isotopes in the foils. The advantage of this method is the cancellation of potential systematic errors from thermal neutron flux, flux profile, foil thickness, foil size, and irradiation time. We have measured the thermal capture cross sections of 136Ce, 156Dy, and 168Yb isotopes, using the high thermal neutron flux from the reactor HANARO at KAERI, and have obtained new cross section values of 7.640.63 barn for 136Ce, 14.82.0 barn for 156Dy, and 133543 barn for 168Yb.

  16. On the capture of dark matter by neutron stars

    SciTech Connect

    Güver, Tolga; Erkoca, Arif Emre; Sarcevic, Ina; Reno, Mary Hall E-mail: aeerkoca@gmail.com E-mail: ina@physics.arizona.edu

    2014-05-01

    We calculate the number of dark matter particles that a neutron star accumulates over its lifetime as it rotates around the center of a galaxy, when the dark matter particle is a self-interacting boson but does not self-annihilate. We take into account dark matter interactions with baryonic matter and the time evolution of the dark matter sphere as it collapses within the neutron star. We show that dark matter self-interactions play an important role in the rapid accumulation of dark matter in the core of the neutron star. We consider the possibility of determining an exclusion region of the parameter space for dark matter mass and dark matter interaction cross section with the nucleons as well as dark matter self-interaction cross section, based on the observation of old neutron stars. We show that for a dark matter density of 10{sup 3} GeV/cm{sup 3}and dark matter mass m{sub χ} ∼< 10 GeV, there is a potential exclusion region for dark matter interactions with nucleons that is three orders of magnitude more stringent than without self-interactions. The potential exclusion region for dark matter self-interaction cross sections is many orders of magnitude stronger than the current Bullet Cluster limit. For example, for high dark matter density regions, we find that for m{sub χ} ∼ 10 GeV when the dark matter interaction cross section with the nucleons ranges from σ{sub χn} ∼ 10{sup −52} cm{sup 2} to σ{sub χn} ∼ 10{sup −57} cm{sup 2}, the dark matter self-interaction cross section limit is σ{sub χχ} ∼< 10{sup −33} cm{sup 2}, which is about ten orders of magnitude stronger than the Bullet Cluster limit.

  17. Quantitative neutron capture radiography for boron in biological specimens.

    PubMed

    Pettersson, O A; Grusell, E; Larsson, B; Huiskamp, R

    1993-08-01

    Track-etch detectors made of cellulose nitrate (LR 115, Kodak Path) and polycarbonate (CR 39, Pershore Mouldings Ltd) were compared regarding sensitivity and background when used as detectors for boron determination in biological samples. Measurements were made on two kinds of sample, cryosectioned biological tissue, and liquid samples deposited directly on the detector surface as microdroplets. The CR 39 films were pretreated or washed before irradiation. When cryosectioned tissue was used, measurements were made with and without the inclusion of Mylar foils between the samples and the detectors. Foil thicknesses used were 2 microns in the case of LR 115 and 2, 4, and 6 microns in the case of CR 39. All samples were irradiated with a thermal-neutron fluence of 5 x 10(12) neutrons cm-2 at the thermal-neutron facility in Studsvik, Sweden. The use of a Mylar foil generally suppressed the background tracks relative to the tracks from the 10B disintegration. No difference in resolution between CR 39 and LR 115 was observed. Pretreatment of the CR 39 resulted in an improved sensitivity of detection but the detector became saturated at 0.25 parts per million of 10B. The background was found to be lower in the pretreated detector. PMID:8367521

  18. The Radiative Strength Function Using the Neutron-Capture Reaction on 94,95Mo

    SciTech Connect

    Sheets, S. A.; Mitchell, G. E.; Agvaanluvsan, U.; Becker, J. A.; Krticka, M.; Becvar, F.

    2006-03-13

    We investigate the energy and multiplicity distributions of gamma-rays following neutron capture in 94,95Mo. By comparing simulated gamma cascades following radiative capture with experimental spectra we try to learn something about the photon strength function at energies below the separation energy. The point of this comparison is to try and confirm recent experiments that found an anomalous low energy enhancement in the photon strength function for molybdenum isotopes.

  19. Leading E1 and M1 contributions to radiative neutron capture on lithium-7

    NASA Astrophysics Data System (ADS)

    Fernando, L.; Higa, R.; Rupak, G.

    2012-02-01

    Using halo effective field theory, we provide a model-independent calculation of the radiative neutron capture on lithium-7 over an energy range where the contribution from the 3+ resonance becomes important. We also present power counting arguments that establish a hierarchy for electromagnetic one- and two-body currents. One finds that a satisfactory description of the capture reaction, in the present single-particle approximation, requires a resonance width about three times larger than the experimentally quoted value.

  20. Use of the power burst facility for boron neutron capture therapy

    SciTech Connect

    Crocker, J.G.; Griebenow, M.L.; Leatham, J.

    1989-01-01

    A program is under development at the Idaho National Engineering Laboratory (INEL) that involves using the Power Burst Facility (PBF) for research into Boron Neutron Capture Therapy (BNCT). BNCT utilizes the ionizing energy from boron-neutron capture to stop reproduction of or destroy cells in cancerous tissue in a two step process. The first step is to selectively concentrate a boron isotope within the tumor cell, that when activated by neutron capture emits highly ionizing, short range particles. The second step involves activation of the isotope only in the vicinity of the tumor with a narrow neutron beam. The INEL program includes the modification of the PBF by the addition of a neutron filter and treatment area. The intense source of epithermal neutrons from PBF is considered necessary to achieve optimum therapy for deep-seated tumors with minimum damage to surface tissue. The INEL program leads to human clinical trials at PBF which is intended to prove that brain tumors can be successfully treated through noninvasive techniques. Further research into BNCT at PBF for other cancer types is also anticipated. 9 refs., 4 figs.

  1. Final Report for the WSU Neutron Capture Therapy Facility Support

    SciTech Connect

    Gerald E. Tripard; Keith G. Fox

    2006-08-24

    The objective for the cooperative research program for which this report has been written was to provide separate NCT facility user support for the students, faculty and scientists who would be doing the U.S. Department of Energy Office (DOE) of Science supported advanced radiotargeted research at the WSU 1 megawatt TRIGA reactor. The participants were the Idaho National laboratory (INL, P.I., Dave Nigg), the Veterinary Medical Research Center of Washington State University (WSU, Janean Fidel and Patrick Gavin), and the Washington State University Nuclear Radiation Center (WSU, P.I., Gerald Tripard). A significant number of DOE supported modifications were made to the WSU reactor in order to create an epithermal neutron beam while at the same time maintaining the other activities of the 1 MW reactor. These modifications were: (1) Removal of the old thermal column. (2) Construction and insertion of a new epithermal filter, collimator and shield. (3) Construction of a shielded room that could accommodate the very high radiation field created by an intense neutron beam. (4) Removal of the previous reactor core fuel cluster arrangement. (5) Design and loading of the new reactor core fuel cluster arrangement in order to optimize the neutron flux entering the epithermal neutron filter. (6) The integration of the shielded rooms interlocks and radiological controls into the SCRAM chain and operating electronics of the reactor. (7) Construction of a motorized mechanism for moving and remotely controlling the position of the entire reactor bridge. (8) The integration of the reactor bridge control electronics into the SCRAM chain and operating electronics of the reactor. (9) The design, construction and attachment to the support structure of the reactor of an irradiation box that could be inserted into position next to the face of the reactor. (Necessitated by the previously mentioned core rearrangement). All of the above modifications were successfully completed and tested. The resulting epithermal beam of 1 x 10{sup 9} n/sec-cm{sup 2} was measured by Idaho National Laboratory with assistance from WSU's Neutron Activation Analysis Group. The beam is as good as our initial proposals for the project had predicted. In addition to all of the design, construction and insertion of the hardware, shielding, electronics and radiation monitoring systems there was considerable manpower and effort put into changes in the Technical Specifications of the reactor and implementing procedures for use of the new facility. This staff involvement is one of the reasons we requested special facility support from the DOE. Once the facility was competed and all of the recalibrations and measurements made to characterize the differences between this reactor core and the previous core we began to assist INL in making their beam measurements with foils and phantoms. Although we proposed support for only one additional staff position to support this new NCT facility the staff support provided by the WSU Nuclear Radiation Center was greater than had been anticipated by our initial proposal. INL was also assisted in the testing of a heavy water (deuterated water) bladder that can be inserted into the collimator in order to produce an intense, external thermal neutron beam. The external epithermal and/or thermal neutron beam capability remains available for use, if funding becomes available for future research projects.

  2. Neutron Resonance Parameters of 55Mn from Reich-Moore Analysis of Recent Experimental Neutron Transmission and Capture Cross Sections

    SciTech Connect

    Derrien, Herve; Leal, Luiz C; Larson, Nancy M; Guber, Klaus H; Wiarda, Dorothea; Arbanas, Goran

    2008-01-01

    High-resolution neutron capture cross section measurements of 55Mn were recently performed at GELINA by Schillebeeckx et al. (2005) and at ORELA by Guber et al. (2007). The analysis of the experimental data was performed with the computer code SAMMY using the Bayesian approach in the resonance parameters representation of the cross sections. The neutron transmission data taken in 1988 by Harvey et al. (2007) and not analyzed before were added to the SAMMY experimental data base. More than 95% of the s-wave resonances and more than 85% of the p-wave resonances were identified in the energy range up to 125 keV, leading to the neutron strength functions S0 = (3.90 0.78) x 10-4 and S1 = (0.45 0.08) x 10-4. About 25% of the d-wave resonances were identified with a possible strength function of S2 = 1.0 x 10-4. The capture cross section calculated at 0.0253 eV is 13.27 b, and the capture resonance integral is 13.52 0.30 b. In the energy range 15 to 120 keV, the average capture cross section is 12% lower than Lerigoleur value and 25% smaller than Macklin value. GELINA and ORELA experimental capture cross sections show a background cross section not described by the Reich-Moore resonance parameters. Part of this background could be due to a direct capture component and/or to the missing d-wave resonances. The uncertainty of 10% on the average capture cross section above 20 keV is mainly due to the inaccuracy in the calculation of the background components.

  3. OPTIMIZATION OF THE EPITHERMAL NEUTRON BEAM FOR BORON NEUTRON CAPTURE THERAPY AT THE BROOKHAVEN MEDICAL RESEARCH REACTOR.

    SciTech Connect

    HU,J.P.; RORER,D.C.; RECINIELLO,R.N.; HOLDEN,N.E.

    2002-08-18

    Clinical trials of Boron Neutron Capture Therapy for patients with malignant brain tumor had been carried out for half a decade, using an epithermal neutron beam at the Brookhaven's Medical Reactor. The decision to permanently close this reactor in 2000 cut short the efforts to implement a new conceptual design to optimize this beam in preparation for use with possible new protocols. Details of the conceptual design to produce a higher intensity, more forward-directed neutron beam with less contamination from gamma rays, fast and thermal neutrons are presented here for their potential applicability to other reactor facilities. Monte Carlo calculations were used to predict the flux and absorbed dose produced by the proposed design. The results were benchmarked by the dose rate and flux measurements taken at the facility then in use.

  4. Optimization of the Epithermal Neutron Beam for Boron Neutron Capture Therapy at the Brookhaven Medical Research Reactor

    SciTech Connect

    Hu, J.P.; Reciniello, R.N.; Holden, N.E.

    2004-05-01

    Clinical trials of Boron Neutron Capture Therapy for patients with malignant brain tumor had been carried out for half a decade, using an epithermal neutron beam at the Brookhaven Medical Reactor. The decision to permanently close this reactor in 2000 cut short the efforts to implement a new conceptual design to optimize this beam in preparation for use with possible new protocols. Details of the conceptual design to produce a higher intensity, more forward-directed neutron beam with less contamination from gamma rays, fast and thermal neutrons are presented here for their potential applicability to other reactor facilities. Monte Carlo calculations were used to predict the flux and absorbed dose produced by the proposed design. The results were benchmarked by the dose rate and flux measurements taken at the facility then in use.

  5. Pre-clinical studies on boron neutron capture therapy.

    PubMed

    Barth, R F; Soloway, A H; Alam, F; Clendenon, N R; Blue, T E; Mafune, N; Goodman, J H; Gordon, W; Bapat, B; Adams, D M

    1989-01-01

    The present report provides an overview of the multidisciplinary research effort on BNCT that currently is in progress at The Ohio State University. Areas under investigation include the preparation of boron containing monoclonal antibodies, the synthesis of boron containing derivatives of promazines and phathalocyanines, the development of a rat model for the treatment of glioblastoma by means of BNCT, the design of an accelerator-based neutron irradiation facility, and 10B concentration measurements using alpha track autoradiographic methods. Progress in each of these areas is described and the direction of future research is indicated. PMID:2751623

  6. Boron neutron capture therapy of malignant brain tumors at the Brookhaven Medical Research Reactor

    SciTech Connect

    Joel, D.D.; Coderre, J.A.; Chanana, A.D.

    1996-12-31

    Boron neutron capture therapy (BNCT) is a bimodal form of radiation therapy for cancer. The first component of this treatment is the preferential localization of the stable isotope {sup 10}B in tumor cells by targeting with boronated compounds. The tumor and surrounding tissue is then irradiated with a neutron beam resulting in thermal neutron/{sup 10}B reactions ({sup 10}B(n,{alpha}){sup 7}Li) resulting in the production of localized high LET radiation from alpha and {sup 7}Li particles. These products of the neutron capture reaction are very damaging to cells, but of short range so that the majority of the ionizing energy released is microscopically confined to the vicinity of the boron-containing compound. In principal it should be possible with BNCT to selectively destroy small nests or even single cancer cells located within normal tissue. It follows that the major improvements in this form of radiation therapy are going to come largely from the development of boron compounds with greater tumor selectivity, although there will certainly be advances made in neutron beam quality as well as the possible development of alternative sources of neutron beams, particularly accelerator-based epithermal neutron beams.

  7. Peculiarities of the abundances of neutron-capture elements in Galactic open clusters

    NASA Astrophysics Data System (ADS)

    Marsakov, V. A.; Gozha, M. L.; Koval', V. V.; Shpigel', L. V.

    2016-01-01

    The properties of the relative abundances of rapid and slow neutron-capture elements are studied using a catalog containing spectroscopic abundance determinations for 14 elements produced in various nuclear-synthesis processes for 90 open clusters. The catalog also contains the positions, ages, velocities, and elements of the Galactic orbits of the clusters. The relative abundances of both r-elements (Eu) and s-elements (Y, Ba, La, and Ce) in clusters with high, elongated orbits and in field stars of the Galactic thin disk display different dependences on metallicity, age, Galactocentric distance, and the elements of the Galactic orbits, supporting the view that these objects have different natures. In young clusters, not only barium, but also the three other studied s-elements display significantly higher relative abundances than field stars of the same metallicity. The relative abundances of Eu are lower in highmetallicity clusters ([Fe/H] > -0.1) with high, elongated orbits than in field giants, on average, while the [Eu/Fe] ratios in lower-metallicity clusters are the same as those in field stars, on average, although with a large scatter. The metallicity dependence of the [O, Mg/Eu] ratios in clusters with high, elongated orbits and in field stars are substantially different. These and other described properties of the Eu abundances, together with the properties of the abundances of primary a-elements, can be understood in a natural way if clusters with high, elongated orbits with different metallicities formed as a result of interactions of two types of high-velocity clouds with the interstellar medium of the Galactic disk: low-metallicity highvelocity clouds that formed from "primordial" gas, and high-metallicity clouds with intermediate velocities that formed in "Galactic fountains."

  8. Characteristics comparison between a cyclotron-based neutron source and KUR-HWNIF for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Tanaka, H.; Sakurai, Y.; Suzuki, M.; Masunaga, S.; Kinashi, Y.; Kashino, G.; Liu, Y.; Mitsumoto, T.; Yajima, S.; Tsutsui, H.; Maruhashi, A.; Ono, K.

    2009-06-01

    At Kyoto University Research Reactor Institute (KURRI), 275 clinical trials of boron neutron capture therapy (BNCT) have been performed as of March 2006, and the effectiveness of BNCT has been revealed. In order to further develop BNCT, it is desirable to supply accelerator-based epithermal-neutron sources that can be installed near the hospital. We proposed the method of filtering and moderating fast neutrons, which are emitted from the reaction between a beryllium target and 30-MeV protons accelerated by a cyclotron accelerator, using an optimum moderator system composed of iron, lead, aluminum and calcium fluoride. At present, an epithermal-neutron source is under construction from June 2008. This system consists of a cyclotron accelerator, beam transport system, neutron-yielding target, filter, moderator and irradiation bed. In this article, an overview of this system and the properties of the treatment neutron beam optimized by the MCNPX Monte Carlo neutron transport code are presented. The distribution of biological effect weighted dose in a head phantom compared with that of Kyoto University Research Reactor (KUR) is shown. It is confirmed that for the accelerator, the biological effect weighted dose for a deeply situated tumor in the phantom is 18% larger than that for KUR, when the limit dose of the normal brain is 10 Gy-eq. The therapeutic time of the cyclotron-based neutron sources are nearly one-quarter of that of KUR. The cyclotron-based epithermal-neutron source is a promising alternative to reactor-based neutron sources for treatments by BNCT.

  9. Neutron-capture Cross Sections from Indirect Measurements

    SciTech Connect

    Escher, J E; Burke, J T; Dietrich, F S; Ressler, J J; Scielzo, N D; Thompson, I J

    2011-10-18

    Cross sections for compound-nuclear reactions play an important role in models of astrophysical environments and simulations of the nuclear fuel cycle. Providing reliable cross section data remains a formidable task, and direct measurements have to be complemented by theoretical predictions and indirect methods. The surrogate nuclear reactions method provides an indirect approach for determining cross sections for reactions on unstable isotopes, which are difficult or impossible to measure otherwise. Current implementations of the method provide useful cross sections for (n,f) reactions, but need to be improved upon for applications to capture reactions.

  10. Experimental Transport Benchmarks for Physical Dosimetry to Support Development of Fast-Neutron Therapy with Neutron Capture Augmentation

    SciTech Connect

    D. W. Nigg; J. K. Hartwell; J. R. Venhuizen; C. A. Wemple; R. Risler; G. E. Laramore; W. Sauerwein; G. Hudepohl; A. Lennox

    2006-06-01

    The Idaho National Laboratory (INL), the University of Washington (UW) Neutron Therapy Center, the University of Essen (Germany) Neutron Therapy Clinic, and the Northern Illinois University(NIU) Institute for Neutron Therapy at Fermilab have been collaborating in the development of fast-neutron therapy (FNT) with concurrent neutron capture (NCT) augmentation [1,2]. As part of this effort, we have conducted measurements to produce suitable benchmark data as an aid in validation of advanced three-dimensional treatment planning methodologies required for successful administration of FNT/NCT. Free-beam spectral measurements as well as phantom measurements with Lucite{trademark} cylinders using thermal, resonance, and threshold activation foil techniques have now been completed at all three clinical accelerator facilities. The same protocol was used for all measurements to facilitate intercomparison of data. The results will be useful for further detailed characterization of the neutron beams of interest as well as for validation of various charged particle and neutron transport codes and methodologies for FNT/NCT computational dosimetry, such as MCNP [3], LAHET [4], and MINERVA [5].

  11. Photoneutron and Photofission Cross Sections for URANIUM-238 and THORIUM-232 Using Neutron Capture Gamma Rays.

    NASA Astrophysics Data System (ADS)

    Varhue, Walter John

    The photofission and total photoneutron cross sections of ('238)U and ('232)Th have been measured as a function of energy between 4 and 11 Mev. The photons used were those produced in the neutron capture reaction in the Tangential Beam Port Facility of the University of Virginia Reactor. The capture gamma ray sources used were the following; Al, Cr, Co, Cu, Fe, Ni, S, and Ti. A computer code was used to calculate the spectrum of each capture gamma ray beam used in the irradiations. This calculation accounted for the attenuation in the beam and the contribution from neutron capture in Al and H. A second code iteratively solved for the best fit cross section curve for the experimentally obtained yield data. In the total photoneutron measurement, the neutrons were counted with a Halpern type detector containing 4 BF(,3) tubes. The intensity of the beam was determined with LiF thermoluminescent dosimeters. The results agree very well with those of previous studies. In the photofission measurement, fission fragments were counted in Lexan polycarbonate, a solid state nuclear track detector. The efficiency of this counting system has been determined analytically as a function of energy with the aid of published experimental measurements of the angular distribution of fission fragments and the etching properties of Lexan. In general the technique has proved to be successful in producing differential photonuclear cross section results. Resolution of the unfolding technique is limited by the density of principal gamma ray lines available from the capture targets. An obvious improvement would be the use of more capture targets. The results and conclusions of previous studies using neutron capture gamma rays have been placed in doubt due to the nature of calculations used to obtain cross values.

  12. Quasi-elastic neutron scattering studies of the slow dynamics of supercooled and glassy aspirin

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Tyagi, Madhusudan; Mamontov, Eugene; Chen, Sow-Hsin

    2012-02-01

    Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent ?(Q) is independent of the wavevector transfer Q in the measured Q range and (ii) the structural relaxation time ?(Q) follows a power-law dependence on Q. Consequently, the Q-independent structural relaxation time ?0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of ?0 can be fitted with the mode-coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by Tokuyama in the measured temperature range. The calculated dynamic response function ?T(Q, t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement langx2rang and the non-Gaussian parameter ?2 extracted from the elastic scattering.

  13. Quasi-Elastic Neutron Scattering Studies of the Slow Dynamics of Supercooled and Glassy Aspirin

    SciTech Connect

    Zhang, Yang; Tyagi, M.; Mamontov, Eugene; Chen, Sow-hsin H

    2011-01-01

    Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 K down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent (Q) is independent of the wave vector transfer Q in the measured Q-range, and (ii) the structural relaxation time (Q) follows a power law dependence on Q. Consequently, the Q-independent structural relaxation time 0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of 0 can be fitted with the mode coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by M. Tokuyama in the measured temperature range. The calculated dynamic response function T(Q,t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows a direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement x2 and non-Gaussian parameter 2 extracted from the elastic scattering.

  14. Independent measurement of the neutrino mixing angle ?13 via neutron capture on hydrogen at Daya Bay

    NASA Astrophysics Data System (ADS)

    An, F. P.; Balantekin, A. B.; Band, H. R.; Beriguete, W.; Bishai, M.; Blyth, S.; Butorov, I.; Cao, G. F.; Cao, J.; Chan, Y. L.; Chang, J. F.; Chang, L. C.; Chang, Y.; Chasman, C.; Chen, H.; Chen, Q. Y.; Chen, S. M.; Chen, X.; Chen, X.; Chen, Y. X.; Chen, Y.; Cheng, Y. P.; Cherwinka, J. J.; Chu, M. C.; Cummings, J. P.; de Arcos, J.; Deng, Z. Y.; Ding, Y. Y.; Diwan, M. V.; Draeger, E.; Du, X. F.; Dwyer, D. A.; Edwards, W. R.; Ely, S. R.; Fu, J. Y.; Ge, L. Q.; Gill, R.; Gonchar, M.; Gong, G. H.; Gong, H.; Gu, W. Q.; Guan, M. Y.; Guo, X. H.; Hackenburg, R. W.; Han, G. H.; Hans, S.; He, M.; Heeger, K. M.; Heng, Y. K.; Hinrichs, P.; Hor, Y. K.; Hsiung, Y. B.; Hu, B. Z.; Hu, L. M.; Hu, L. J.; Hu, T.; Hu, W.; Huang, E. C.; Huang, H.; Huang, X. T.; Huber, P.; Hussain, G.; Isvan, Z.; Jaffe, D. E.; Jaffke, P.; Jen, K. L.; Jetter, S.; Ji, X. P.; Ji, X. L.; Jiang, H. J.; Jiao, J. B.; Johnson, R. A.; Kang, L.; Kettell, S. H.; Kramer, M.; Kwan, K. K.; Kwok, M. W.; Kwok, T.; Lai, W. C.; Lau, K.; Lebanowski, L.; Lee, J.; Lei, R. T.; Leitner, R.; Leung, A.; Leung, J. K. C.; Lewis, C. A.; Li, D. J.; Li, F.; Li, G. S.; Li, Q. J.; Li, W. D.; Li, X. N.; Li, X. Q.; Li, Y. F.; Li, Z. B.; Liang, H.; Lin, C. J.; Lin, G. L.; Lin, P. Y.; Lin, S. K.; Lin, Y. C.; Ling, J. J.; Link, J. M.; Littenberg, L.; Littlejohn, B. R.; Liu, D. W.; Liu, H.; Liu, J. L.; Liu, J. C.; Liu, S. S.; Liu, Y. B.; Lu, C.; Lu, H. Q.; Luk, K. B.; Ma, Q. M.; Ma, X. Y.; Ma, X. B.; Ma, Y. Q.; McDonald, K. T.; McFarlane, M. C.; McKeown, R. D.; Meng, Y.; Mitchell, I.; Monari Kebwaro, J.; Nakajima, Y.; Napolitano, J.; Naumov, D.; Naumova, E.; Nemchenok, I.; Ngai, H. Y.; Ning, Z.; Ochoa-Ricoux, J. P.; Olshevski, A.; Patton, S.; Pec, V.; Peng, J. C.; Piilonen, L. E.; Pinsky, L.; Pun, C. S. J.; Qi, F. Z.; Qi, M.; Qian, X.; Raper, N.; Ren, B.; Ren, J.; Rosero, R.; Roskovec, B.; Ruan, X. C.; Shao, B. B.; Steiner, H.; Sun, G. X.; Sun, J. L.; Tam, Y. H.; Tang, X.; Themann, H.; Tsang, K. V.; Tsang, R. H. M.; Tull, C. E.; Tung, Y. C.; Viren, B.; Vorobel, V.; Wang, C. H.; Wang, L. S.; Wang, L. Y.; Wang, M.; Wang, N. Y.; Wang, R. G.; Wang, W.; Wang, W. W.; Wang, X.; Wang, Y. F.; Wang, Z.; Wang, Z.; Wang, Z. M.; Webber, D. M.; Wei, H. Y.; Wei, Y. D.; Wen, L. J.; Whisnant, K.; White, C. G.; Whitehead, L.; Wise, T.; Wong, H. L. H.; Wong, S. C. F.; Worcester, E.; Wu, Q.; Xia, D. M.; Xia, J. K.; Xia, X.; Xing, Z. Z.; Xu, J. Y.; Xu, J. L.; Xu, J.; Xu, Y.; Xue, T.; Yan, J.; Yang, C. C.; Yang, L.; Yang, M. S.; Yang, M. T.; Ye, M.; Yeh, M.; Yeh, Y. S.; Young, B. L.; Yu, G. Y.; Yu, J. Y.; Yu, Z. Y.; Zang, S. L.; Zeng, B.; Zhan, L.; Zhang, C.; Zhang, F. H.; Zhang, J. W.; Zhang, Q. M.; Zhang, Q.; Zhang, S. H.; Zhang, Y. C.; Zhang, Y. M.; Zhang, Y. H.; Zhang, Y. X.; Zhang, Z. J.; Zhang, Z. Y.; Zhang, Z. P.; Zhao, J.; Zhao, Q. W.; Zhao, Y.; Zhao, Y. B.; Zheng, L.; Zhong, W. L.; Zhou, L.; Zhou, Z. Y.; Zhuang, H. L.; Zou, J. H.; Daya Bay Collaboration

    2014-10-01

    A new measurement of the ?13 mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of the ?13 measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GWth reactors, the rate deficit observed at the far hall is interpreted as sin22?13=0.0830.018 in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain sin22?13=0.0890.008 as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.

  15. Monte-Carlo Quantum Chemistry of Biogene Amines. Laser and Neutron Capture Effects

    SciTech Connect

    Glushkov, A. V.; Malinovskaya, S. V.; Khetselius, O. Yu.; Loboda, A. V.

    2009-03-09

    Monte-Carlo quantum calculation of the cluster consisting of the serotonine ST (histamine HM) molecules and 100 molecules of water is carried out. It is found that the zwitterion appears as expected to be strongly favoured with respect to neutral molecule. The perspective possibilities of laser and neutron capture action on different biomolecules are indicated.

  16. Stellar Neutron Capture Cross Sections of the Lu and Hf Isotopes

    SciTech Connect

    Wisshak, K.; Voss, F.; Kaeppeler, F.; Kazakov, L.; Krticka, M.

    2005-05-24

    The neutron capture cross sections of 175,176Lu and 176,177,178,179,180Hf have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.7 MV Van de Graaff accelerator relative to the gold standard. Neutrons were produced by the 7Li(p,n)7Be reaction and capture events were detected by the Karlsruhe 4{pi}BaF2 detector. The cross section ratios could be determined with uncertainties between 0.9 and 1.8% about a factor of five more accurate than previous data. A strong population of isomeric states was found in neutron capture of the Hf isotopes, which are only partially explained by CASINO/GEANT simulations based on the known level schemes.Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 8 keV and 100 keV. Severe differences up to40% were found to the data of a recent evaluation based on existing experimental results. The new data allow for a much more reliable analysis of the important branching in the s-process synthesis path at 176Lu which can be interpreted as an s-process thermometer.

  17. Monte-Carlo Quantum Chemistry of Biogene Amines. Laser and Neutron Capture Effects

    NASA Astrophysics Data System (ADS)

    Glushkov, A. V.; Malinovskaya, S. V.; Khetselius, O. Yu.; Loboda, A. V.

    2009-03-01

    Monte-Carlo quantum calculation of the cluster consisting of the serotonine ST (histamine HM) molecules and 100 molecules of water is carried out. It is found that the zwitterion appears as expected to be strongly favoured with respect to neutral molecule. The perspective possibilities of laser and neutron capture action on different biomolecules are indicated.

  18. Neutron-Capture Gamma-Ray Data for Obtaining Elemental Abundances from Planetary Spectra

    NASA Technical Reports Server (NTRS)

    Frankle, S. C.; Reedy, R. C.

    2001-01-01

    Newly compiled and evaluated energies and intensities of gamma rays made by the capture of thermal neutrons by elements from H to Zn plus Ge, Sm, and Gd are reported for use in determining elemental composition by planetary gamma-ray spectroscopy. Additional information is contained in the original extended abstract.

  19. Using {sup 171,173}Yb(d,p{gamma}) to Benchmark a Surrogate Reaction for Neutron Capture

    SciTech Connect

    Hatarik, R.; Cizewski, J. A.; Hatarik, A. M.; O'Malley, P. D.; Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Lesher, S. R.; Gibelin, J.; Phair, L.; Swan, T.

    2009-03-10

    The {sup 171,173}Yb(d,p{gamma}) reactions have been measured to determine the efficacy of this reaction as a surrogate for neutron capture on radioactive nuclei. Preliminary results for the surrogate cross section ratios, with gating conditions that best mimic the spin distribution of neutron capture, reproduce the Wisshak et al., (n,{gamma}) cross section ratios within 15%.

  20. Correlated γ rays following capture of thermal neutrons on 113Cd

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Jandel, M.; Arnold, C. W.; Bredeweg, T. A.; Couture, A.; Mosby, S. M.; Ullmann, J. L.; Krtička, M.

    2013-10-01

    Natural cadmium is often used as the shielding against thermal neutrons and component in detectors sensitive to neutrons, because of the large cross section of 113Cd for capture of neutrons with energies below 1 eV. Investigation of the neutron-capture γ rays from the 113Cd (n , γ) reaction is of importance for these applications. We report the intensity distributions of these cascade γ-ray transitions. The neutron-capture experiment on 113Cd has been carried out at LANL's LANSCE using the 4 π BaF2 DANCE array. The measured two-dimensional spectrum of counts vs. γ-ray energy vs. γ-ray multiplicity from the strongest resonance in the 113Cd (n , γ) reaction at 0.178 eV has been compared with predictions from the statistical model using the code DICEBOX. Work supported by the NNSA Office of Nonproliferation and Verification Research and Development performed under the Department of Energy contract DE-AC52-06NA25396.

  1. Design of neutron beams at the Argonne Continuous Wave Linac (ACWL) for boron neutron capture therapy and neutron radiography

    SciTech Connect

    Zhou, X.L.; McMichael, G.E.

    1994-10-01

    Neutron beams are designed for capture therapy based on p-Li and p-Sc reactions using the Argonne Continuous Wave Linac (ACWL). The p-Li beam will provide a 2.5 {times} 10{sup 9} n/cm{sup 2}s epithermal flux with 7 {times} 10{sup 5} {gamma}/cm{sup 2}s contamination. On a human brain phantom, this beam allows an advantage depth (AD) of 10 cm, an advantage depth dose rate (ADDR) of 78 cGy/min and an advantage ratio (AR) of 3.2. The p-Sc beam offers 5.9 {times} 10{sup 7} n/cm{sup 2}s and a dose performance of AD = 8 cm and AR = 3.5, suggesting the potential of near-threshold (p,n) reactions such as the p-Li reaction at E{sub p} = 1.92 MeV. A thermal radiography beam could also be obtained from ACWL.

  2. Neutron capture cross section measurements at the beam line 04 of J-PARC/MLF

    SciTech Connect

    Igashira, Masayuki; Harada, Hideo; Kiyanagi, Yoshiaki

    2012-11-12

    An Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) at the beam line 04 of MLF (Material and Life Sciences Experimental Facilities) of J-PARC (Japan Proton Accelerator Research Complex) was installed to measure neutron capture cross sections related to the research and development of innovative nuclear systems, the study on nuclear astrophysics, etc. ANNRI has two gamma-ray spectrometers: one is a Ge detector array placed at 22 m from the coupled type moderator of the spallation neutron source of J-PARC/MLF and the other is a pair of NaI(Tl) detectors at 28 m. Until the 11th of March, 2011, when we had big earthquakes, we measured capture cross sections of Zr-93, Tc-99, Pd-107, I-129, Cm-244, Cm-246, etc. After checking and repairing ANNRI, we restarted measurements, and ANNRI has been open to worldwide users at present.

  3. Two-step γ cascades following thermal neutron capture in Gd,157155

    NASA Astrophysics Data System (ADS)

    Valenta, S.; Bečvář, F.; Kroll, J.; Krtička, M.; Tomandl, I.

    2015-12-01

    Spectra of two-step γ cascades following neutron capture in Gd,157155 are measured using the two-Ge-detector facility installed at the thermal neutron beam of the research reactor LVR-15 at Řež. The main objective of this experiment is to obtain new information on photon strength functions, with the emphasis on the role of M 1 scissors-mode vibration. An analysis of accumulated γ -ray spectra, made within the statistical model, leads to the conclusion that the scissors mode significantly affects γ decay of all states of studied nuclei. Experimental data are compared to photon strength functions deduced from other experiments. Agreement of our results with those obtained from DANCE measurement of γ spectra following resonance neutron capture is obtained.

  4. Optimization study for an epithermal neutron beam for boron neutron capture therapy at the University of Virginia Research Reactor

    SciTech Connect

    Burns, T.D. Jr.

    1995-05-01

    The non-surgical brain cancer treatment modality, Boron Neutron Capture Therapy (BNCT), requires the use of an epithermal neutron beam. This purpose of this thesis was to design an epithermal neutron beam at the University of Virginia Research Reactor (UVAR) suitable for BNCT applications. A suitable epithermal neutron beam for BNCT must have minimal fast neutron and gamma radiation contamination, and yet retain an appreciable intensity. The low power of the UVAR core makes reaching a balance between beam quality and intensity a very challenging design endeavor. The MCNP monte carlo neutron transport code was used to develop an equivalent core radiation source, and to perform the subsequent neutron transport calculations necessary for beam model analysis and development. The code accuracy was validated by benchmarking output against experimental criticality measurements. An epithermal beam was designed for the UVAR, with performance characteristics comparable to beams at facilities with cores of higher power. The epithermal neutron intensity of this beam is 2.2 {times} 10{sup 8} n/cm{sup 2} {center_dot} s. The fast neutron and gamma radiation KERMA factors are 10 {times} 10{sup {minus}11}cGy{center_dot}cm{sup 2}/n{sub epi} and 20 {times} 10{sup {minus}11} cGy{center_dot}cm{sup 2}/n{sub epi}, respectively, and the current-to-flux ratio is 0.85. This thesis has shown that the UVAR has the capability to provide BNCT treatments, however the performance characteristics of the final beam of this study were limited by the low core power.

  5. 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.

  6. Status of the Neutron Capture Measurement on 237Np with the DANCE Array at LANSCE

    SciTech Connect

    Esch, E.-I.; Bond, E.M.; Bredeweg, T. A.; Glover, S. E.; Haight, R. C.; Kronenberg, A.; O'Donnell, J. M.; Pitcher, E. J.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wender, S. A.; Wouters, J. M.; Alpizar-Vicente, A.; Greife, U.; Hatarik, R.

    2005-05-24

    Neptunium-237 is a major constituent of spent nuclear fuel. Estimates place the amount of 237Np bound for the Yucca Mountain high-level waste repository at 40 metric tons. The Department of Energy's Advanced Fuel Cycle Initiative program is evaluating methods for transmuting the actinide waste that will be generated by future operation of commercial nuclear power plants. The critical parameter that defines the transmutation efficiency of actinide isotopes is the neutron fission-to-capture ratio for the particular isotope in a given neutron spectrum. The calculation of transmutation efficiency therefore requires accurate fission and capture cross sections. Current 237Np evaluations available for transmuter system studies show significant discrepancies in both the fission and capture cross sections in the energy regions of interest. Herein we report on 237Np (n,{gamma}) measurements using the recently commissioned DANCE array.

  7. Parametrization of low-energy cross sections for nonresonant neutron capture

    SciTech Connect

    Wang Chengbin; Cisse, Ousmane I.; Baye, Daniel

    2009-09-15

    The nonresonant component of radiative neutron capture reactions is parametrized at low energies by a polynomial of second degree. The potential model is first used to reproduce experimental data below 1 MeV with the help of spectroscopic factors. The fits are found sensitive to the scattering length of the initial s or p waves. The coefficients of a Taylor expansion are then calculated by resolution of the Schroedinger equation and its energy derivatives at energy zero. Such theory-guided parametrizations are derived for neutron capture by {sup 7}Li, {sup 12}C, {sup 14}C, {sup 16}O, and {sup 18}O. When the capture proceeds from the s wave to a weakly bound state, a Pade-like parametrization better approximates the potential-model results.

  8. Coupled-Channel Computation of Direct Neutron Capture on Non-Spherical Nuclei

    NASA Astrophysics Data System (ADS)

    Arbanas, Goran; Thompson, Ian; Escher, Jutta; Nunes, Filomena; Elster, Charlotte; Zhang, Shi-Sheng

    2014-09-01

    Models of direct neutron capture of neutrons have so far accounted for the effects of non-spherical nuclei either in the incoming wave functions (via non-spherical optical model potentials), or in the final bound states (via non-spherical real potential wells), but not in both. Since it is known that spherical optical potentials do not give a good reproduction of low energy neutron-scattering observables of deformed nuclei, we have performed calculations in which the initial and final states are both treated in a self-consistent, non-spherical-nucleus picture. We have done this in the coupled-channels model of nuclear reactions implemented in the FRESCO code by using the same deformation-length for the couplings to the rotational-band states in the incoming and the final state configurations. We compute direct capture using this method for even-mass calcium isotopes 40 , 42 , 44 , 46 , 48Ca to study the effect across the two closed neutron shells, for neutron-rich even-mass tin isotopes relevant to models of astrophysical nucleosynthesis, and for 56Fe that is an important structural material used in nuclear applications. Models of direct neutron capture of neutrons have so far accounted for the effects of non-spherical nuclei either in the incoming wave functions (via non-spherical optical model potentials), or in the final bound states (via non-spherical real potential wells), but not in both. Since it is known that spherical optical potentials do not give a good reproduction of low energy neutron-scattering observables of deformed nuclei, we have performed calculations in which the initial and final states are both treated in a self-consistent, non-spherical-nucleus picture. We have done this in the coupled-channels model of nuclear reactions implemented in the FRESCO code by using the same deformation-length for the couplings to the rotational-band states in the incoming and the final state configurations. We compute direct capture using this method for even-mass calcium isotopes 40 , 42 , 44 , 46 , 48Ca to study the effect across the two closed neutron shells, for neutron-rich even-mass tin isotopes relevant to models of astrophysical nucleosynthesis, and for 56Fe that is an important structural material used in nuclear applications. This work was performed under the auspices of the U.S. D.O.E. by UT-Battelle, LLC, Contract No. DE-AC0500OR22725, and by Lawrence Livermore National Laboratory, Contract DE-AC52-07NA27344.

  9. [Epithermal neutron capture therapy]. Progress and status report

    SciTech Connect

    Not Available

    1993-05-01

    Development of a 4 mA, 2.5 MeV Tandem Cascade Accelerator (TCA) for the production of neutrons via the {sup 7}Li(p,n){sup 7}Be nuclear reaction is currently nearing completion at SRL. The TCA is a tandem electrostatic accelerator which uses a high current negative ion source in conjunction with a high current solid state cascade multiplier power supply to provide a compact, low cost, proton accelerator capable of supplying multi-milliampere currents at several million electron volts. The inherent simplicity and flexibility of this accelerator provide several features which are desirable for laboratory and clinical applications requiring the generation of high neutron fluxes. The beam aperture of the accelerating tube is large so that critical focusing and alignment of the beam is not required. Both the ion beam source and target are at ground potential during operation. This configuration allows different moderator geometries to be incorporated easily into the target design. A high degree of compactness is achieved by a patented SRL design which allows the power supply to be mounted directly onto the accelerating column thereby eliminating the need for an external power supply chassis. The TCA is unique in its capability to accelerate multi-milliampere ion beams to 2.5 MeV. A direct result of the patented high current solid-state power supply developed by SRL and the use of a high current, high brightness multicusp negative ion source. The TCA requires no RF or magnetic fields which greatly reduces the system weight, power dissipation and heat load on auxiliary systems when compared with radiofrequency quadrupole (RFQ) or cyclotron-type accelerators. Delivery of current is continuous, rather than pulsed as in an RFQ, which reduces the peak thermal and mechanical stresses on the target and simplifies target design. The accelerator weighs less than 2,000 lbs., has an overall length of approximately 2.6 m, and requires approximately 25 kW of electrical power.

  10. 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.

  11. In-phantom two-dimensional thermal neutron distribution for intraoperative boron neutron capture therapy of brain tumours

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Matsumura, A.; Yamamoto, K.; Kumada, H.; Shibata, Y.; Nose, T.

    2002-07-01

    The aim of this study was to determine the in-phantom thermal neutron distribution derived from neutron beams for intraoperative boron neutron capture therapy (IOBNCT). Gold activation wires arranged in a cylindrical water phantom with (void-in-phantom) or without (standard phantom) a cylinder styrene form placed inside were irradiated by using the epithermal beam (ENB) and the mixed thermal-epithermal beam (TNB-1) at the Japan Research Reactor No 4. With ENB, we observed a flattened distribution of thermal neutron flux and a significantly enhanced thermal flux delivery at a depth compared with the results of using TNB-1. The thermal neutron distribution derived from both the ENB and TNB-1 was significantly improved in the void-in-phantom, and a double high dose area was formed lateral to the void. The flattened distribution in the circumference of the void was observed with the combination of ENB and the void-in-phantom. The measurement data suggest that the ENB may provide a clinical advantage in the form of an enhanced and flattened dose delivery to the marginal tissue of a post-operative cavity in which a residual and/or microscopically infiltrating tumour often occurs. The combination of the epithermal neutron beam and IOBNCT will improve the clinical results of BNCT for brain tumours.

  12. Dosimetric implications of new compounds for neutron capture therapy (NCT)

    SciTech Connect

    Fairchild, R.G.

    1982-01-01

    Systemic application of radiolabeled or cytotoxic agents should allow targeting of primary and metastatic neoplasms on a cellular level. In fact, drug uptake in non-target cell pools often exceeds toxic levels before sufficient amounts are delivered to tumor. In addition, at the large concentration of molecules necessary for therapy, effects of saturation are often found. Application of NCT can circumvent problems associated with high uptake in competing non-target cell pools, as the /sup 10/B(n,..cap alpha..)/sup 7/Li reaction is activated only within the radiation field. A comparison with other modes of particle therapy indicated that NCT provides significant advantages. It is however, difficult to obtain vehicles for boron transport which demonstrate both the tumor specificity and concentration requisite for NCT. A number of biomolecules have been investigated which show both the necessary concentration and specificity. These include chlorpromazine, thiouracil, porphyrins, amino acids, and nucleosides. However, these analogs have yet to be made available for NCT. Dosimetric implications of binding sites are considered, as well as alternate neutron sources. (ERB)

  13. Commercial Clinical Application of Boron Neutron Capture Therapy

    SciTech Connect

    N /A

    1999-09-03

    CRADA No. 95-CR-09 among the LITCO--now Bechtel BWXT Idaho, LLC; a private company, Neutron Therapies Limited Liability Company, NTL formerly Ionix Corporation; and Washington State University was established in 1996 to further the development of BNCT. NTL has established a laboratory for the synthesis, under US FDA approved current Good Manufacturing Practices (cGMP) guidelines, of key boron intermediates and final boron agents for BNCT. The company has focused initially on the development of the compound GB-10 (Na{sub 2}B{sub 10}H{sub 10}) as the first boron agent of interest. An Investigational New Drug (IND) application for GB-10 has been filed and approved by the FDA for a Phase I human biodistribution trial in patients with non-small cell lung cancer and glioblastoma multiforme at UW under the direction of Professor Keith Stelzer, Principal Investigator (PI). These trials are funded by NTL under a contract with the UW, Department of Radiation Oncology, and the initial phases are nearing completion. Initial results show that boron-10 concentrations on the order of 100 micrograms per gram (100 ppm) can be achieved and maintained in blood with no indication of toxicity.

  14. Neutron capture cross section measurement of 151Sm at the CERN neutron time of flight facility (n_TOF).

    PubMed

    Abbondanno, U; Aerts, G; Alvarez-Velarde, F; Alvarez-Pol, H; Andriamonje, S; Andrzejewski, J; Badurek, G; Baumann, P; Becvr, F; Benlliure, J; Berthoumieux, E; Calvio, F; Cano-Ott, D; Capote, R; Cennini, P; Chepel, V; Chiaveri, E; Colonna, N; Cortes, G; Cortina, D; Couture, A; Cox, J; Dababneh, S; Dahlfors, M; David, S; Dolfini, R; Domingo-Pardo, C; Duran, I; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Frais-Koelbl, H; Furman, W; Goncalves, I; Gallino, R; Gonzalez-Romero, E; Goverdovski, A; Gramegna, F; Griesmayer, E; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martinez, A; Isaev, S; Jericha, E; Kppeler, F; Kadi, Y; Karadimos, D; Kerveno, M; Ketlerov, V; Koehler, P; Konovalov, V; Krticka, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martinez-Val, J; Mastinu, P; Mengoni, A; Milazzo, P M; Molina-Coballes, A; Moreau, C; Mosconi, M; Neves, F; Oberhummer, H; O'Brien, S; Pancin, J; Papaevangelou, T; Paradela, C; Pavlik, A; Pavlopoulos, P; Perlado, J M; Perrot, L; Pignatari, M; Plag, R; Plompen, A; Plukis, A; Poch, A; Policarpo, A; Pretel, C; Quesada, J; Raman, S; Rapp, W; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, C; Rudolf, G; Rullhusen, P; Salgado, J; Soares, J C; Stephan, C; Tagliente, G; Tain, J; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarin, D; Vincente, M C; Vlachoudis, V; Voss, F; Wendler, H; Wiescher, M; Wisshak, K

    2004-10-15

    The151Sm(n,gamma)152Sm cross section has been measured at the spallation neutron facility n_TOF at CERN in the energy range from 1 eV to 1 MeV. The new facility combines excellent resolution in neutron time-of-flight, low repetition rates, and an unsurpassed instantaneous luminosity, resulting in rather favorable signal/background ratios. The 151Sm cross section is of importance for characterizing neutron capture nucleosynthesis in asymptotic giant branch stars. At a thermal energy of kT=30 keV the Maxwellian averaged cross section of this unstable isotope (t(1/2)=93 yr) was determined to be 3100+/-160 mb, significantly larger than theoretical predictions. PMID:15524972

  15. Final Stage in the Design of a Boron Neutron Capture Therapy facility at CEADEN, Cuba

    SciTech Connect

    Cabal, F. Padilla; Martin, G.

    2008-08-11

    A neutron beam simulation study is carried out to determine the most suitable neutron energy for treatment of shallow and deep-seated brain tumors in the context of Boron Neutron Capture Therapy (BNCT). Two figures-of-merit, the therapeutic gain and the neutron fluence are utilized as beam assessment parameters. An irradiation cavity is used instead of a parallel beam port for the therapy. Calculations are performed using the MCNP5 code. After the optimization of our beam-shaper a study of the dose distribution in the head, neck, tyroids, lungs and upper and middle spine had been made. The therapeutic gain is increased while the current required for one hour treatment is decreased in comparison with the trading prototypes of NG used for BNCT.

  16. Final Stage in the Design of a Boron Neutron Capture Therapy facility at CEADEN, Cuba

    NASA Astrophysics Data System (ADS)

    Cabal, F. Padilla; Martn, G.

    2008-08-01

    A neutron beam simulation study is carried out to determine the most suitable neutron energy for treatment of shallow and deep-seated brain tumors in the context of Boron Neutron Capture Therapy (BNCT). Two figures-of-merit, the therapeutic gain and the neutron fluence are utilized as beam assessment parameters. An irradiation cavity is used instead of a parallel beam port for the therapy. Calculations are performed using the MCNP5 code. After the optimization of our beam-shaper a study of the dose distribution in the head, neck, tyroids, lungs and upper and middle spine had been made. The therapeutic gain is increased while the current required for one hour treatment is decreased in comparison with the trading prototypes of NG used for BNCT

  17. MAGIC polymer gel for dosimetric verification in boron neutron capture therapy.

    PubMed

    Uusi-Simola, Jouni; Heikkinen, Sami; Kotiluoto, Petri; Sern, Tom; Seppl, Tiina; Auterinen, Iiro; Savolainen, Sauli

    2007-01-01

    Radiation sensitive polymer gels are among the most promising three-dimensional dose verification tools developed to date. Polymer gel dosimeter known by the acronym MAGIC has been tested for evaluation of its use in boron neutron capture (BNCT) dosimetry. We irradiated a large (diameter 10 cm, length 20 cm) cylindrical gel phantom in the epithermal neutron beam of the Finnish BNCT facility at the FiR 1 nuclear reactor. Neutron irradiation was simulated with a Monte Carlo radiation transport code MCNP. Gel samples from the same production batch were also irradiated with 6 MV photons from a medical linear accelerator to compare dose response in the two different types of beams. Irradiated gel phantoms were imaged using MRI to determine their relaxation rate R2 maps. The measured and normalized dose distribution in the epithermal neutron beam was compared to the dose distribution calculated by computer simulation. The results support the feasibility MAGIC gel in BNCT dosimetry. PMID:17592463

  18. Gel dosimeters as useful dose and thermal-fluence detectors in boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Gambarini, G.; Moss, R. L.; Mariani, M.; Carrara, M.; Daquino, G. G.; Nievaart, V. A.; Valente, M.; Vanossi, E.

    The dosimetry method based on Fricke-Xylenol-Orange-infused gels in form of layers has shown noticeable potentiality for in-phantom or in-free-beam dose and thermal flux profiling and imaging in the high fluxes of thermal or epithermal neutrons utilised for boron neutron capture therapy (BNCT). Gel-dosimeters in form of layers give the possibility not only of obtaining spatial dose distributions but also of achieving measurements of each dose contribution in neutron fields. The discrimination of the various dose components is achieved by means of pixel-to-pixel manipulations of pairs of images obtained with gel-dosimeters having different isotopic composition. It is possible to place large dosimeters, detecting in such a way large dose images, because the layer geometry of dosimeters avoids sensitive variation of neutron transport due to the gel isotopic composition. Some results obtained after the last improvements of the method are reported.

  19. Neutron capture on Zr94: Resonance parameters and Maxwellian-averaged cross sections

    NASA Astrophysics Data System (ADS)

    Tagliente, G.; Milazzo, P. M.; Fujii, K.; Abbondanno, U.; Aerts, G.; lvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Badurek, G.; Baumann, P.; Be?v?, F.; Belloni, F.; Berthoumieux, E.; Bisterzo, S.; Calvio, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapio, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrari, A.; Ferreira-Marques, R.; Furman, W.; Gallino, R.; Goncalves, I.; Gonzalez-Romero, E.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Jericha, E.; Kppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Kossionides, E.; Krti?ka, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martnez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.

    2011-07-01

    The neutron capture cross sections of the Zr isotopes play an important role in nucleosynthesis studies. The s-process reaction flow between the Fe seed and the heavier isotopes passes through the neutron magic nucleus Zr90 and through Zr91,92,93,94, but only part of the flow extends to Zr96 because of the branching point at Zr95. Apart from their effect on the s-process flow, the comparably small isotopic (n,?) cross sections make Zr also an interesting structural material for nuclear reactors. The Zr94 (n,?) cross section has been measured with high resolution at the spallation neutron source n_TOF at CERN and resonance parameters are reported up to 60 keV neutron energy.

  20. Monte Carlo simulation of biological effects of boron neutron capture irradiation with d(14)+Be neutrons in vitro

    SciTech Connect

    Poeller, F.; Sauerwein, W.

    1995-04-01

    It was shown that radiation effects in tumor cells treated with fast neutrons may be increased by the neutron capture reaction {sup 10}B(n,{alpha}){sup 7}Li. The classic approach for macroscopic dosimetry in fast-neutron therapy cannot be applied to the dose in boron neutron capture therapy (BNCT). The effectiveness of BNCT in killing tumor cells depends on the number of {sup 10}B atoms delivered to the tumor, the subcellular distribution of {sup 10}B and the thermal neutron fluence at the site of the tumor. Monte Carlo calculations of the energy dispositions of short-range particles with high LET coming from {sup 10}B disintegrations were performed and compared to the observed biological effects. The simulation allows us to study the influence of the localization of intracellular {sup 10}B in the nucleus, cytoplasm, plasma membrane or extracellular space. The biological response function which describes the probability of the lethal effect produced by a single particle track through the cell nucleus was found by comparing the calculated microscopic dose distribution spectra for single events with the survival observed experimentally. Calculations for a human melanoma cell population treated as a monolayer in the presence or absence of boron with d(14)+Be neutrons will be demonstrated. Two different boron compounds enriched in {sup 10}B were investigated in this study: boric acid (H{sub 3}{sup 10}BO{sub 3}) and p-dihydroxyboryl phenylalanine (BPA). The study shows that a high fraction of BPA enters the cytoplasm while boric acid was found only in the extracellular space. The computer simulations indicate that BPA yields a higher potential effectiveness for inactivation of melanoma cells than boric acid. 52 refs., 9 figs., 3 tabs.

  1. Optimization of a moderator assembly for use in an accelerator-based neutron source for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Woollard, Jeffrey Earl

    In this dissertation, the development and application of in-phantom neutron field optimization parameters for use in evaluating neutron fields for Boron Neutron Capture Therapy (BNCT) is presented. These parameters are based on dose rate distributions in a head phantom and include the effects of fractionation and an energy dependent normal-tissue neutron RBE. As a step in the development of these parameters, a methodology for calculating the energy dependent normal-tissue neutron RBE, RBE(Esbn), was developed. This methodology was used to obtain reasonable estimates for the RBE of neutrons, as a function of neutron energy, for skeletal muscle and brain tissue. Additionally, a sensitivity analysis was performed to examine the robustness of the calculations of RBE(Esbn) to necessary assumptions regarding the level of cell-survival at tolerance for brain. This analysis showed that differences in the RBE-dose rate as a function of depth in an ellipsoidal head phantom, as a result of different assumptions regarding the level of cell-survival at tolerance, were negligible, thus increasing our confidence in our mathematical method. The in-phantom neutron field optimization parameters were used to evaluate the neutron fields produced by several potential moderator assemblies and to determine the optimum moderator assembly for use in our Accelerator-Based Neutron Source (ABNS) for BNCT. Based on a comparison of the calculated in-phantom neutron field optimization parameters, for a single irradiation from the superior aspect, a 10 mA proton beam current, and the specified treatment parameters, a BeO-Lisb2COsb3 moderator assembly, with a 20 cm thick BeO moderator, was found to be the optimum moderator assembly for use in the ABNS. The second best moderator assembly was a Dsb2O-Lisb2COsb3 moderator assembly with a 25 cm thick Dsb2O moderator. An optimization analysis, based on in-air optimization parameters, was also performed on the same moderator assemblies considered in the in-phantom moderator assembly optimization analysis. This analysis concluded that the moderator assemblies shown as optimum in the in-phantom moderator assembly optimization analysis, were also the optimum moderator assemblies based on the in-air parameters. This indicates that both types of parameters agree on the optimal neutron field for use in an ABNS for BNCT.

  2. Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium

    SciTech Connect

    G. Leinweber; J.A. Burke; H.D. Knox; N.J. Drindak; D.W. Mesh; W.T. Haines; R.V. Ballad; R.C. Block; R.E. Slovacek; C.J. Werner; M.J. Trbovich; D.P. Barry; T. Sato

    2001-07-16

    The purpose of the present work is to accurately measure the neutron cross sections of samarium. The most significant isotope is {sup 149}Sm, which has a large neutron absorption cross section at thermal energies and is a {sup 235}U fission product with a 1% yield. Its cross sections are thus of concern to reactor neutronics. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic institute (RPI) LINAC facility using metallic and liquid Sm samples. The capture measurements were made at the 25 meter flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-meter flight stations with {sup 6}Li glass scintillation detectors. Resonance parameters were determined by a combined analysis of six experiments (three capture and three transmission) using the multi-level R-matrix Bayesian code SAMMY version M2. The significant features of this work are as follows. Dilute samples of samarium nitrate in deuterated water (D{sub 2}O) were prepared to measure the strong resonances at 0.1 and 8 eV without saturation. Disk-shaped spectroscopic quartz cells were obtained with parallel inner surfaces to provide a uniform thickness of solution. The diluent feature of the SAMMY program was used to analyze these data. The SAMMY program also includes multiple scattering corrections to capture yield data and resolution functions specific to the RPI facility. Resonance parameters for all stable isotopes of samarium were deduced for all resonances up to 30 eV. Thermal capture cross-section and capture resonance integral calculations were made using the resultant resonance parameters and were compared to results obtained using resonance parameters from ENDF/B-VI updated through release 3. Extending the definition of the capture resonance integral to include the strong 0.1 eV resonance in {sup 149}Sm, present measurements agree within estimated uncertainties with EnDF/B-VI release 3. The thermal capture cross-section was calculated from the present measurements of the resonance parameters and also agrees with ENDF within estimated uncertainties. The present measurements reduce the statistical uncertainties in resonance parameters compared to prior measurements.

  3. Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications

    SciTech Connect

    Pigni, Marco T; Massimi, C.; Vannini, G.; Koehler, Paul; Bisterzo, S.; Gallino, R.; Colonna, N.; Lorusso, G.; Barbagallo, M.; Marrone, S.; Tagliente, G.; Terlizzi, R.; Gunsing, F.; Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Carrapico, C.; Dridi, W.; Lampoudis, C.; Pancin, J.; Perrot, L.; Plukis, A.; Kaeppeler, K.; Dillmann, I.; Mosconi, M.; Plag, R.; Voss, F.; Walter, S.; Wisshak, K.; Mengoni, A.; Capote, R.; Frais-Koelbl, H.; Griesmayer, E.; Mengoni, A.; Calviani, M.; Cennini, P.; Chiaveri, E.; Dahlfors, M.; Ferrari, A.; Fitzpatrick, L.; Herrera-Martinez, A.; Kadi, Y.; Losito, R.; Sarchiapone, L.; Vlachoudis, V.; Wendler, H.; Pignatari, M.; Rauscher, T.; Abbondanno, U.; Belloni, F.; Fujii, K.; Milazzo, P. M.; Moreau, C.; Alvarez, H.; Duran, I.; Paradela, C.; Tarrio, D.; Alvarez-Velarde, F.; Cano-Ott, D.; Embid-Segura, M.; Gonzalez-Romero, E.; Guerrero, C.; Martinez, T.; Mendoza, E.; Villamarin, D.; Andrzejewski, J.; Marganiec, J.; Assimakopoulos, P. A.; Karadimos, D.; Karamanis, D.; Papachristodoulou, C.; Patronis, N.; Audouin, L.; et al.

    2012-01-01

    We have measured the neutron capture cross sections of the stable magnesium isotopes {sup 24,25,26}Mg in the energy range of interest to the s process using the neutron time-of-flight facility n{_}TOF at CERN. Capture events from a natural metal sample and from samples enriched in {sup 25}Mg and {sup 26}Mg were recorded using the total energy method based on C{sub 6}{sup 2}H{sub 6} detectors. Neutron resonance parameters were extracted by a simultaneous resonance shape analysis of the present capture data and existing transmission data on a natural isotopic sample. Maxwellian-averaged capture cross sections for the three isotopes were calculated up to thermal energies of 100 keV and their impact on s-process analyses was investigated. At 30 keV the new values of the stellar cross section for {sup 24}Mg, {sup 25}Mg, and {sup 26}Mg are 3.8 {+-} 0.2 mb, 4.1 {+-} 0.6 mb, and 0.14 {+-} 0.01 mb, respectively.

  4. Diversity of abundance patterns of neutron-capture elements in very metal-poor stars

    NASA Astrophysics Data System (ADS)

    Aoki, Misa; Aoki, Wako; Ishimaru, Yuhri; Wanajo, Shinya

    2014-05-01

    Observations of Very Metal-Poor stars indicate that there are at least two sites to r-process; "weak r-process" and "main r-process". A question is whether these two are well separated or there exists a variation in the r-process. We present the results of abundance analysis of neutron-capture elements in the two Very Metal-Poor stars HD107752 and HD110184 in the Milky Way halo observed with the Subaru Telescope HDS. The abundance patterns show overabundace at light n-capture elements (e.g. Sr, Y), inferring the element yielding of weak r-process, while heavy neutron-capture elements (e.g. Ba, Eu) are deficient; however, the overabundance of light ones is not as significant as that previously found in stars representing the weak r-process (e.g. HD122563; Honda et al. 2006). Our study show diversity in the abundance patterns from light to heavy neutron-capture elements in VMP stars, suggesting a variation in r-process, which may depend on electron fraction of environment.

  5. Diversity of abundance patterns of neutron-capture elements in very metal-poor stars

    SciTech Connect

    Aoki, Misa; Ishimaru, Yuhri; Aoki, Wako; Wanajo, Shinya

    2014-05-02

    Observations of Very Metal-Poor stars indicate that there are at least two sites to r-process; “weak r-process” and “main r-process”. A question is whether these two are well separated or there exists a variation in the r-process. We present the results of abundance analysis of neutron-capture elements in the two Very Metal-Poor stars HD107752 and HD110184 in the Milky Way halo observed with the Subaru Telescope HDS. The abundance patterns show overabundace at light n-capture elements (e.g. Sr, Y), inferring the element yielding of weak r-process, while heavy neutron-capture elements (e.g. Ba, Eu) are deficient; however, the overabundance of light ones is not as significant as that previously found in stars representing the weak r-process (e.g. HD122563; Honda et al. 2006). Our study show diversity in the abundance patterns from light to heavy neutron-capture elements in VMP stars, suggesting a variation in r-process, which may depend on electron fraction of environment.

  6. A simple method for the analysis of neutron resonance capture spectra

    NASA Astrophysics Data System (ADS)

    Clarijs, Martijn C.; Bom, Victor R.; van Eijk, Carel W. E.

    2009-03-01

    Neutron resonance capture analysis (NRCA) is a method used to determine the bulk composition of various kinds of objects and materials. It is based on analyzing direct capture resonance peaks. However, the analysis is complicated by scattering followed by capture effects in the object itself. These effects depend on the object's shape and size. In this paper the new Delft elemental analysis program (DEAP) is presented which can automatically and quickly analyze multiple NRCA spectra in a practical and simple way, yielding the elemental bulk composition of an object, largely independent of its shape and size. The DEAP method is demonstrated with data obtained with a Roman bronze water tap excavated in Nijmegen (The Netherlands). DEAP will also be used in the framework of the Ancient Charm project as data analysis program for neutron resonance capture imaging (NRCI) experiments. NRCI provides three-dimensional visualization and quantification of the internal structure of archaeological objects by performing scanning measurements with narrowly collimated neutron beams on archaeological objects in computed tomography based experimental setups. The large amounts (hundreds to thousands) of spectra produced during a NRCI experiment can automatically and quickly be analyzed by DEAP.

  7. A simple method for the analysis of neutron resonance capture spectra

    SciTech Connect

    Clarijs, Martijn C.; Bom, Victor R.; Eijk, Carel W. E. van

    2009-03-15

    Neutron resonance capture analysis (NRCA) is a method used to determine the bulk composition of various kinds of objects and materials. It is based on analyzing direct capture resonance peaks. However, the analysis is complicated by scattering followed by capture effects in the object itself. These effects depend on the object's shape and size. In this paper the new Delft elemental analysis program (DEAP) is presented which can automatically and quickly analyze multiple NRCA spectra in a practical and simple way, yielding the elemental bulk composition of an object, largely independent of its shape and size. The DEAP method is demonstrated with data obtained with a Roman bronze water tap excavated in Nijmegen (The Netherlands). DEAP will also be used in the framework of the Ancient Charm project as data analysis program for neutron resonance capture imaging (NRCI) experiments. NRCI provides three-dimensional visualization and quantification of the internal structure of archaeological objects by performing scanning measurements with narrowly collimated neutron beams on archaeological objects in computed tomography based experimental setups. The large amounts (hundreds to thousands) of spectra produced during a NRCI experiment can automatically and quickly be analyzed by DEAP.

  8. Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications

    NASA Astrophysics Data System (ADS)

    Massimi, C.; Koehler, P.; Bisterzo, S.; Colonna, N.; Gallino, R.; Gunsing, F.; Kppeler, F.; Lorusso, G.; Mengoni, A.; Pignatari, M.; Vannini, G.; Abbondanno, U.; Aerts, G.; lvarez, H.; lvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Barbagallo, M.; Baumann, P.; Be?v?, F.; Belloni, F.; Bennett, M.; Berthoumieux, E.; Calviani, M.; Calvio, F.; Cano-Ott, D.; Capote, R.; Carrapio, C.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Dolfini, R.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Goncalves, I.; Gonzlez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Herwig, F.; Hirschi, R.; Igashira, M.; Isaev, S.; Jericha, E.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Ketlerov, V.; Konovalov, V.; Kopecky, S.; Kossionides, E.; Krti?ka, M.; Lampoudis, C.; Leeb, H.; Lederer, C.; Lindote, A.; Lopes, I.; Losito, R.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Martnez, T.; Mastinu, P.; Mendoza, E.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rockefeller, G.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Salgado, J.; Santos, C.; Sarchiapone, L.; Sarmento, R.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tarro, D.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vaz, P.; Ventura, A.; Villamarin, D.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.

    2012-04-01

    We have measured the neutron capture cross sections of the stable magnesium isotopes 24,25,26Mg in the energy range of interest to the s process using the neutron time-of-flight facility n_TOF at CERN. Capture events from a natural metal sample and from samples enriched in 25Mg and 26Mg were recorded using the total energy method based on C62H6 detectors. Neutron resonance parameters were extracted by a simultaneous resonance shape analysis of the present capture data and existing transmission data on a natural isotopic sample. Maxwellian-averaged capture cross sections for the three isotopes were calculated up to thermal energies of 100 keV and their impact on s-process analyses was investigated. At 30 keV the new values of the stellar cross section for 24Mg, 25Mg, and 26Mg are 3.80.2 mb, 4.10.6 mb, and 0.140.01 mb, respectively.

  9. Rates for neutron-capture reactions on tungsten isotopes in iron meteorites. [Abstract only

    NASA Technical Reports Server (NTRS)

    Masarik, J.; Reedy, R. C.

    1994-01-01

    High-precision W isotopic analyses by Harper and Jacobsen indicate the W-182/W-183 ratio in the Toluca iron meteorite is shifted by -(3.0 +/- 0.9) x 10(exp -4) relative to a terrestrial standard. Possible causes of this shift are neutron-capture reactions on W during Toluca's approximately 600-Ma exposure to cosmic ray particles or radiogenic growth of W-182 from 9-Ma Hf-182 in the silicate portion of the Earth after removal of W to the Earth's core. Calculations for the rates of neutron-capture reactions on W isotopes were done to study the first possibility. The LAHET Code System (LCS) which consists of the Los Alamos High Energy Transport (LAHET) code and the Monte Carlo N-Particle(MCNP) transport code was used to numerically simulate the irradiation of the Toluca iron meteorite by galactic-cosmic-ray (GCR) particles and to calculate the rates of W(n, gamma) reactions. Toluca was modeled as a 3.9-m-radius sphere with the composition of a typical IA iron meteorite. The incident GCR protons and their interactions were modeled with LAHET, which also handled the interactions of neutrons with energies above 20 MeV. The rates for the capture of neutrons by W-182, W-183, and W-186 were calculated using the detailed library of (n, gamma) cross sections in MCNP. For this study of the possible effect of W(n, gamma) reactions on W isotope systematics, we consider the peak rates. The calculated maximum change in the normalized W-182/W-183 ratio due to neutron-capture reactions cannot account for more than 25% of the mass 182 deficit observed in Toluca W.

  10. The measurements of parity violation in resonant neutron-capture reactions

    SciTech Connect

    Sharapov, E.I.; Popov, Y.P. ); Wender, S.A.; Seestrom, S.J.; Bowman, C.D. ); Postma, H. ); Gould, C.R. ); Wasson, A. )

    1990-01-01

    The study of parity violation in total (n,{gamma}) cross sections on {sup 139}La and {sup 117}Sn targets was performed at the LANSCE pulsed neutron source using longitudinally polarized neutrons and a BaF{sub 2} detector. The effect of parity nonconservation in the {sup 139}La(n,{gamma}) reaction for the resonance at E{sub n}=0.73 eV was confirmed. New results for p-wave resonances in the {sup 117}Sn(n, {gamma}) reaction were obtained. A comparison between the capture and transmission techniques is presented. 12 refs., 5 figs., 1 tab.

  11. Feasibility study on pinhole camera system for online dosimetry in boron neutron capture therapy.

    PubMed

    Katabuchi, Tatsuya; Hales, Brian; Hayashizaki, Noriyosu; Igashira, Masayuki; Khan, Zareen; Kobayashi, Tooru; Matsuhashi, Taihei; Miyazaki, Koichi; Ogawa, Koichi; Terada, Kazushi

    2014-06-01

    The feasibility of a pinhole camera system for online dosimetry in boron neutron capture therapy (BNCT) was studied. A prototype system was designed and built. Prompt ?-rays from the (10)B(n,?)(7)Li reaction from a phantom irradiated with neutrons were detected with the prototype system. An image was reconstructed from the experimental data. The reconstructed image showed a good separation of the two borated regions in the phantom. The counting rates and signal-to-noise ratio when using the system in actual BNCT applications are also discussed. PMID:24433991

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

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

    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.

  13. Parametric study of dynamic s-process neutron-capture nucleosynthesis: nuclear data needs

    SciTech Connect

    Mathews, G.J.; Howard, W.M.; Takahashi, K.; Ward, R.A.

    1984-09-01

    We summarize the stellar parameters which characterize the s-process sigma N curve in the framework of models which produce an exponential distribution of exposures by periodic time-dependent neutron irradiations. The optimum parameter space, defined by the best fit to the solar-system sigma N curve, is distinctively different than the classical smooth monotonically decreasing curve. Constraints are placed on the s-process environment. The needs for better neutron-capture data in various mass regions are highlighted. 19 references.

  14. 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.

  15. Measurement of Parity-Violating Neutron Capture Gamma Asymmetries at Low-Energies

    SciTech Connect

    Barron-Palos, L.; Bowman, James D; Fomin, Nadia; Greene, G. L.; Penttila, Seppo I

    2009-01-01

    A sensitive measurement of parity-violating (PV) observables in few-nucleon systems can shed light on our current understanding of the hadronic weak interaction at low momentum transfers. Theoretical models describe the nucleon-nucleon weak interaction at low energies with 6 parameters that need, in principle, to be determined in the same number of independent experiments. In this context, a series of experiments with cold neutrons are being proposed and developed. Particularly, experiments that aim to measure the parity-violating asymmetry in the distribution of the gamma-rays emitted in the capture of polarized neutrons by protons and deuterium, will be discussed in this paper.

  16. 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.

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

    PubMed

    Kononov, O E; Kononov, V N; Bokhovko, M V; Korobeynikov, V V; Soloviev, A N; Sysoev, A S; Gulidov, I A; Chu, W T; Nigg, D W

    2004-11-01

    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 (7)Li(p,n)(7)Be reaction as a neutrons source. An optimal configuration is suggested for the beam shaping assembly made from polytetrafluoroethylene and magnesium fluorine to be placed on high current IPPE proton accelerator KG-2.5. Results of calculation were experimentally tested and are in good agreement with measurements. PMID:15308184

  18. Detection of Neutrons with Scintillation Counters

    DOE R&D Accomplishments Database

    Hofstadter, R.

    1948-11-01

    Detection of slow neutrons by: detection of single gamma rays following capture by cadmium or mercury; detection of more than one gamma ray by observing coincidences after capture; detection of heavy charged particles after capture in lithium or baron nuclei; possible use of anthracene for counting fast neutrons investigated briefly.

  19. Experimental evaluation of boron neutron capture therapy of human breast carcinoma implanted on nude mice

    NASA Astrophysics Data System (ADS)

    Bose, Satya Ranjan

    2000-06-01

    An in-pool small animal irradiation neutron tube (SAINT) facility was designed, constructed and installed at the University of Virginia Nuclear Research Reactor (UVAR). Thermal neutron flux profiles were measured by foil activation analysis (gold) and verified with DORT and MCNP computer code models. The gamma-ray absorbed dose in the neutron-gamma mixed field was determined from TLD measurements. The SAINT thermal neutron flux was used to investigate the well characterized human breast cancer cell line MCF-7B on both in-vitro samples and in- vivo animal subjects. Boronophenylalanine (BPA enriched in 95% 10B) was used as a neutron capturing agent. The in-vitro response of MCF-7B human breast carcinoma cells to BPA in a mixed field of neutron-gamma radiation or pure 60Co gamma radiation was investigated. The best result (lowest surviving fraction) was observed in cell cultures pre-incubated with BPA and given the neutron irradiation. The least effective treatment consisted of 60Co irradiation only. Immunologically deficient nude mice were inoculated subcutaneously with human breast cancer MCF-7B cells and estradiol pellets (to support tumor growth). The tumor volume in the mouse control group increased over time, as expected. The group of mice exposed only to neutron treatment exhibited initial tumor volume reduction lasting until 35 days following the treatment, followed by renewed tumor growth. Both groups given BPA plus neutron treatment showed continuous reduction in tumor volume over the 55-day observation period. The group given the higher BPA concentration showed the best tumor reduction response. The results on both in-vitro and in-vivo studies showed increased cell killing with BPA, substantiating the incorporation of BPA into the tumor or cell line. Therefore, BNCT may be a possible choice for the treatment of human breast carcinoma. However, prior to the initiation of any clinical studies, it is necessary to determine the therapeutic efficacy in a large animal model.

  20. Radiative capture of fast neutrons by /sup 165/Ho and /sup 238/U

    SciTech Connect

    McDainels, D K; Varghese, P; Drake, D M; Arthur, E; Lindholm, A; Bergqvist, I; Krumlinde, J

    1982-04-01

    Radiative capture of fast neutrons by the deformed nuclei /sup 165/Ho and /sup 238/U was measured over the 7- to 15-MeV incident neutron energy range. The ..gamma..-ray detector was a large NaI(T1) anti-Compton spectrometer, and time-of-flight techniques were used to suppress background. The total radiative capture cross section exhibits an energy dependence that clearly indicates the importance of the direct-semidirect reaction mechanism. Theoretical calculations compare favorably with experimental observations. However, the shapes of the observed ..gamma..-ray spectra differ from those calculated, indicating problems in estimating the distribution of single-particle strength for these deformed nuclei.

  1. Using 171,173Yb(d,p) to benchmark a surrogate reaction for neutron capture

    SciTech Connect

    Hatarik, R; Bersntein, L; Burke, J; Cizewski, J; Gibelin, J; Lesher, S; O'Malley, P; Phair, L; Swan, T

    2008-08-08

    Neutron capture cross sections on unstable nuclei are important for many applications in nuclear structure and astrophysics. Measuring these cross sections directly is a major challenge and often impossible. An indirect approach for measuring these cross sections is the surrogate reaction method, which makes it possible to relate the desired cross section to a cross section of an alternate reaction that proceeds through the same compound nucleus. To benchmark the validity of using the (d,p{gamma}) reaction as a surrogate for (n,{gamma}), the {sup 171,173}Yb(d,p{gamma}) reactions were measured with the goal to reproduce the known [1] neutron capture cross section ratios of these nuclei.

  2. Validating (d,pγ) as a Surrogate for Neutron Capture

    NASA Astrophysics Data System (ADS)

    Ratkiewicz, A.; Cizewski, J. A.; Pain, S. D.; Adekola, A. S.; Burke, J. T.; Casperson, R. J.; Fotiades, N.; McCleskey, M.; Burcher, S.; Shand, C. M.; Austin, R. A. E.; Baugher, T.; Carpenter, M. P.; Devlin, M.; Escher, J. E.; Hardy, S.; Hatarik, R.; Howard, M. E.; Hughes, R. O.; Jones, K. L.; Kozub, R. L.; Lister, C. J.; Manning, B.; O'Donnell, J. M.; Peters, W. A.; Ross, T. J.; Scielzo, N. D.; Seweryniak, D.; Zhu, S.

    2015-05-01

    The r-process is responsible for creating roughly half of the elements heavier than iron. It has recently become understood that the rates at which neutron capture reactions proceed at late times in the r-process may dramatically affect the final abundance pattern. However, direct measurements of neutron capture reaction rates on exotic nuclei are exceptionally difficult, necessitating the development of indirect approaches such as the surrogate technique. The (d,pγ) reaction at low energies was identified as a promising surrogate for the (n,γ) reaction, as both reactions share many characteristics. We report on a program to validate (d,pγ) as a surrogate for (n,γ) using 95Mo as a target. The experimental campaign includes direct measurements of the γ-ray intensities from the decay of excited states populated in the 95Mo(n,γ) and 95Mo(d,pγ) reactions.

  3. Determination of Thermal Neutron Capture Cross-Sections at Budapest PGAA Facility

    SciTech Connect

    Revay, Zsolt; Belgya, Tamas; Firestone, Richard B.

    2007-10-26

    Prompt gamma activation analysis (PGAA) is a powerful nuclear analytical technique to determine the elemental and isotopic composition of materials. The PGAA facility at Budapest, Hungary is one of the leading laboratories of the world, determining spectroscopic data for chemical analysis to be used in other laboratories. These partial gamma-ray production cross-sections and k{sub 0} values, being proportional to the analytical sensitivities of the chemical elements, can be transformed into thermal neutron capture cross-sections, i.e. the probabilities of the (n,{gamma}) reactions, which are of broader interest in different fields of nuclear physics. Some preliminary results on thermal neutron capture cross-sections are presented.

  4. Validating (d,pγ) as a surrogate for neutron capture

    SciTech Connect

    Ratkiewicz, A.; Cizewski, J. A.; Pain, S. D.; Adekola, A. S.; Burke, J. T.; Casperson, R. J.; Fotiadis, Nikolaos; McCleskey, M.; Burcher, S.; Shand, C. M; Austin, R. A. E.; Baugher, T.; Carpenter, M. P.; Devlin, Matthew James; Escher, J. E.; Hardy, S.; Hatarik, R.; Howard, M. E.; Hughes, R. O.; Jones, K. L.; Kozub, R. L.; Lister, C. J.; Manning, B.; O'Donnell, John M.; Peters, W. A.; Ross, T. J.; Scielzo, N. D.; Seweryniak, D.; Zhu, S.

    2015-02-13

    The r-process is responsible for creating roughly half of the elements heavier than iron. It has recently become understood that the rates at which neutron capture reactions proceed at late times in the r-process may dramatically affect the final abundance pattern. However, direct measurements of neutron capture reaction rates on exotic nuclei are exceptionally difficult, necessitating the development of indirect approaches such as the surrogate technique. The (d,pγ) reaction at low energies was identified as a promising surrogate for the (n,γ) reaction, as both reactions share many characteristics. We report on a program to validate (d,pγ) as a surrogate for (n,γ) using 95Mo as a target. The experimental campaign includes direct measurements of the γ-ray intensities from the decay of excited states populated in the 95Mo(n,γ) and 95Mo(d,pγ) reactions.

  5. Validating (d,p gamma) as a Surrogate for Neutron Capture

    SciTech Connect

    Ratkiewicz, A.; Cizewski, J.A.; Pain, S.D.; Adekola, A.S.; Burke, J.T.; Casperson, R.J.; Fotiades, N.; McCleskey, M.; Burcher, S.; Shand, C.M.; Austin, R.A.E.; Baugher, T.; Carpenter, M.P.; Devlin, M.; Escher, J.E.; Hardy, S.; Hatarik, R.; Howard, M.E.; Hughes, R.O.; Jones, K.L.; Kozub, R.L.; Lister, C.J.; Manning, B.; O’Donnell, J.M.; Peters, W.A.; Ross, T.J.; Scielzo, N.D.; Seweryniak, D.; Zhu, S.; Schwengner, R.; Zuber, K.

    2015-05-28

    The r-process is responsible for creating roughly half of the elements heavier than iron. It has recently become understood that the rates at which neutron capture reactions proceed at late times in the r-process may dramatically affect the final abundance pattern. However, direct measurements of neutron capture reaction rates on exotic nuclei are exceptionally difficult, necessitating the development of indirect approaches such as the surrogate technique. The (d,pγ) reaction at low energies was identified as a promising surrogate for the (n,γ) reaction, as both reactions share many characteristics. We report on a program to validate (d,pγ) as a surrogate for (n,γ) using 95Mo as a target. The experimental campaign includes direct measurements of the γ-ray intensities from the decay of excited states populated in the 95Mo(n,γ) and 95Mo(d,pγ) reactions.

  6. Validating (d,p gamma) as a Surrogate for Neutron Capture

    DOE PAGESBeta

    Ratkiewicz, A.; Cizewski, J.A.; Pain, S.D.; Adekola, A.S.; Burke, J.T.; Casperson, R.J.; Fotiades, N.; McCleskey, M.; Burcher, S.; Shand, C.M.; et al

    2015-05-28

    The r-process is responsible for creating roughly half of the elements heavier than iron. It has recently become understood that the rates at which neutron capture reactions proceed at late times in the r-process may dramatically affect the final abundance pattern. However, direct measurements of neutron capture reaction rates on exotic nuclei are exceptionally difficult, necessitating the development of indirect approaches such as the surrogate technique. The (d,pγ) reaction at low energies was identified as a promising surrogate for the (n,γ) reaction, as both reactions share many characteristics. We report on a program to validate (d,pγ) as a surrogate formore » (n,γ) using 95Mo as a target. The experimental campaign includes direct measurements of the γ-ray intensities from the decay of excited states populated in the 95Mo(n,γ) and 95Mo(d,pγ) reactions.« less

  7. Numerical characterization of a tomographic system for online dose measurements in Boron Neutron Capture Therapy

    SciTech Connect

    Minsky, D. M.; Valda, A. A.; Somacal, H.; Burlon, A. A.; Kreiner, A. J.

    2007-02-12

    A tomographic system for online dose measurements in Boron Neutron Capture Therapy (BNCT) based on the measurement of a specific 478 keV {gamma}-ray emitted after the neutron capture in boron is being developed. In the present work we study by means of Monte Carlo numerical simulations the effects of the finite spatial resolution and the limited number of counts, i. e. the statistical noise, on the reconstructed image contrast of numerical phantoms. These phantoms, of simple geometry, mimic the tumor (specific) and the normal tissue (non specific) boron concentrations. The simulated projection data were reconstructed using the expectation-maximization maximum-likelihood algorithm. These studies will help in the improvement of BNCT dosimetry.

  8. Neutron Capture Elements in the Open Cluster Chemical Abundance & Mapping (OCCAM) Survey

    NASA Astrophysics Data System (ADS)

    O'Connell, Julia; Frinchaboy, Peter M.; Shetrone, Matthew D.; Hearty, Fred R.; Majewski, Steven R.; Zasowski, Gail; Sdss /Apogee-1, III

    2015-01-01

    The Open Cluster Chemical Abundance & Mapping (OCCAM) survey is a systematic survey of Galactic open clusters using data primarily from the SDSS-III/APOGEE-1 survey. The high-resolution (R=22,500), near-infrared (H-band) APOGEE-1 survey allows for cluster membership probability determination and analysis of light and iron-peak elements. Neutron capture elements, however, prove to be elusive in the IR region covered by APOGEE. In an effort to fully study detailed Galactic chemical evolution, we conducted a high resolution (R~60,000) spectroscopic abundance analysis of neutron capture elements for OCCAM clusters in the optical regime to complement the APOGEE results. We present results based on prominent resonance lines for Eu, La, Ba, and Ce in the ~5400-6750 AA range using data obtained at McDonald Observatory with the 2.1m Otto Struve telescope and Sandiford Echelle Spectrograph.

  9. Numerical characterization of a tomographic system for online dose measurements in Boron Neutron Capture Therapy

    NASA Astrophysics Data System (ADS)

    Minsky, D. M.; Valda, A. A.; Burlon, A. A.; Kreiner, A. J.; Somacal, H.

    2007-02-01

    A tomographic system for online dose measurements in Boron Neutron Capture Therapy (BNCT) based on the measurement of a specific 478 keV γ-ray emitted after the neutron capture in boron is being developed. In the present work we study by means of Monte Carlo numerical simulations the effects of the finite spatial resolution and the limited number of counts, i. e. the statistical noise, on the reconstructed image contrast of numerical phantoms. These phantoms, of simple geometry, mimic the tumor (specific) and the normal tissue (non specific) boron concentrations. The simulated projection data were reconstructed using the expectation-maximization maximum-likelihood algorithm. These studies will help in the improvement of BNCT dosimetry.

  10. Analytical sensitivities and energies of thermal neutron capture gamma rays II

    USGS Publications Warehouse

    Senftle, F.E.; Moore, H.D.; Leep, D.B.; El-Kady, A.; Duffey, D.

    1971-01-01

    A table of the analytical sensitivities of the principal lines in the thermal neutron capture gamma-ray spectrum from 0 to 3 MeV has been compiled for most of the elements. A tabulation of the full-energy, single-escape, and double-escape peaks has also been made according to energy. The tables are useful for spectral interpretation and calibration. ?? 1971.

  11. Analytical sensitivities and energies of thermal-neutron-capture gamma rays

    USGS Publications Warehouse

    Duffey, D.; El-Kady, A.; Senftle, F.E.

    1970-01-01

    A table of the analytical sensitivities of the principal lines in the thermal-neutron-capture gamma ray spectrum has been compiled for most of the elements. In addition a second table of the full-energy, single-escape, and double-escape peaks has been compiled according to energy for all significant lines above 3 MeV. Lines that contrast well with adjacent lines are noted as prominent. The tables are useful for spectral interpretation and calibration. ?? 1970.

  12. Boron neutron capture therapy for oral precancer: proof of principle in an experimental animal model

    SciTech Connect

    A. Monti Hughes; ECC Pozzi; S. Thorp; M. A. Garabalino; R. O. Farias; S. J. Gonzalez; E. M. Heber; M. E. Itoiz; R. F. Aromando; A. J. Molinari; M. Miller; D. W. Nigg; P. Curotto; V. A. Trivillin; A. E. Schwint

    2013-11-01

    Field-cancerized tissue can give rise to second primary tumours, causing therapeutic failure. Boron neutron capture therapy (BNCT) is based on biological targeting and would serve to treat undetectable foci of malignant transformation. The aim of this study was to optimize BNCT for the integral treatment for oral cancer, with particular emphasis on the inhibitory effect on tumour development originating in precancerous conditions, and radiotoxicity of different BNCT protocols in a hamster cheek pouch oral precancer model.

  13. Gamma-ray cascade transitions from resonant neutron capture in Cd-111 and Cd-113

    SciTech Connect

    Rusev, Gencho Y.

    2012-08-27

    A neutron-capture experiment on {sup nat}Cd has been carried out at DANCE. Multiple-fold coincidence {gamma}-ray spectra have been collected from J=0, 1 resonances in {sup 111}Cd and {sup 113}Cd. The cascades ending at the ground state can be described by the SLO model while the cascades ending at the 2+ states are better reproduced by the mixed SLO+KMF model.

  14. Case numbers for a randomized clinical trial of boron neutron capture therapy for Glioblastoma multiforme.

    PubMed

    Sander, Anja; Wosniok, Werner; Gabel, Detlef

    2014-06-01

    Boron neutron capture therapy (BNCT) with Na2B12H11SH (BSH) or p-dihydroxyborylphenylalanine (BPA), and with a combination of both, was compared to radiotherapy with temozolomide, and the number of patients required to show statistically significant differences between the treatments was calculated. Whereas arms using BPA require excessive number of patients in each arm, a two-armed clinical trial with BSH and radiotherapy plus temozolomide is feasible. PMID:24373823

  15. Long-survivors of glioblatoma treated with boron neutron capture therapy (BNCT).

    PubMed

    Kageji, T; Mizobuchi, Y; Nagahiro, S; Nakagawa, Y; Kumada, H

    2011-12-01

    The purpose of this study was to compare the radiation dose between long-survivors and non-long-survivors in patients with glioblatoma (GBM) treated with boron neutron capture therapy (BNCT). Among 23 GBM patients treated with BNCT, there were five patients who survived more than three years after diagnosis. The physical and weighted dose of the minimum gross tumor volume (GTV) of long-survivors was much higher than that of non-long survivors with significant statistical differences. PMID:21463946

  16. Observing Infrared Emission Lines of Neutron-Capture Species in Planetary Nebulae: New Detections with IGRINS

    NASA Astrophysics Data System (ADS)

    Dinerstein, Harriet L.; Sterling, N. C.; Kaplan, Kyle F.; Bautista, Manuel A.

    2015-08-01

    As the former envelopes of evolved stars, planetary nebulae (PNe) present an opportunity to study slow neutron-capture reactions (the s-process) during the AGB. Such studies differ from those of AGB stars in two ways. First, PNe represent the end point of self-enrichment and dredge-up in the star and most of its mass return to the ISM, enabling us to infer the nucleosynthetic yield of a specific element. Second, some s-process products are observable in PNe but difficult or impossible to observe in cool stars. These include some species with nuclear charge Z in the 30s for which the major synthesis sites are uncertain. Optical emission lines of trans-iron species have been observed in some PNe, but are faint and can suffer from blending with lines of more abundant elements (Pquignot & Baluteau 1994, A&A, 283, 593; Sharpee et al. 2007, ApJ, 659, 1265). Observing infrared transitions from low energy states has proven to be a fruitful alternate approach. We used K-band lines of Se (Z=34) and Kr (Z=36) to study the demographics of their abundances in a large sample of Milky Way PNe (Dinerstein 2001, ApJ, 550, L223; Sterling & Dinerstein 2008, ApJ, 174, 158; Sterling, Porter, & Dinerstein 2015, submitted). An L-band emission line of Zn identified by Dinerstein & Geballe (2001, ApJ, 562, 515) and further observed by Smith, Zijlstra, & Dinerstein 2014 (MNRAS, 441, 3161), can be used as a tracer of the Fe-group, enabling determinations of the key stellar population diagnostic ratio [alpha/Fe] in PNe (see poster by Dinerstein et al., Focus Meeting 4). Using IGRINS, a high spectral resolution H and K band spectrometer (Park & Jaffe et al. 2014, Proc SPIE, 9147), we have discovered several new lines not previously reported in any astronomical object. Our detection of an H-band line of Rb (Z=37) confirms previous claims of optical Rb detections and indicates enrichment by a factor of ~4 in the PN NGC 7027 (Sterling, Dinerstein, Kaplan, & Bautista, in preparation). We also detect lines that we tentatively identify as Ge (Z=32) and Cd (Z=48). This work was supported by NSF grants AST 0708429 and 1412928.

  17. Neutron-induced capture cross sections of short-lived actinides with the surrogate reaction method

    NASA Astrophysics Data System (ADS)

    Ache, M.; Boutoux, G.; Jurado, B.; Barreau, G.; Matthieu, L.; Czajkowski, S.; Dassie, D.; Haas, B.; Mot, V.; Roig, O.; Gaudefroy, L.; Taieb, J.; Pillet, N.; Faul, T.; Srot, O.; Bauge, E.; Gunsing, F.

    2010-03-01

    Determination of neutron-capture cross sections of short-lived nuclei is opening the way to understand and clarify the properties of many nuclei of interest for nuclear structure physics, nuclear astrophysics and particularly for transmutation of nuclear wastes. The surrogate approach is well-recognized as a potentially very useful method to extract neutron cross sections for low-energy compound-nuclear reactions and to overcome the difficulties related to the target radioactivity. In this work we will assess where we stand on these neutron-capture cross section measurements and how we can achieve the short-lived Minor Actinides nuclei involved in the nuclear fuel cycle. The CENBG collaboration applied the surrogate method to determine the neutron-capture cross section of 233Pa (T1/2 = 27 d). The 233Pa (n,?) cross section is then deduced from the measured gamma decay probability of 234Pa compound nucleus formed via the surrogate 232Th(3He,p) reaction channel. The obtained cross section data, covering the neutron energy range 0.1 to 1 MeV, have been compared with the predictions of the Hauser-Feshbach statistical model. The importance of establishing benchmarks is stressed for the minor actinides region. However, the lack of desired targets led us to propose recently the 174Yb (3He,p?) reaction as a surrogate reaction for the (n,?) predetermined benchmark cross section of 175Lu. An overview of the experimental setup combining gamma ray detectors such as Ge and C6D6 in coincidence with light charged particles ?E-E Telescopes will be presented and preliminary results will be discussed.

  18. Experimental boron neutron capture therapy for melanoma: Systemic delivery of boron to melanotic and amelanotic melanoma

    SciTech Connect

    Coderre, J.A.; Glass, J.D.; Micca, P.; Greenberg, D. ); Packer, S. North Shore University Hospital Manhasset, NY )

    1990-01-01

    The boron-containing melanin precursor analogue p-boronophenylalanine (BPA) has previously been shown to selectively deliver boron to pigmented murine melanomas when administered in a single intragastric dose. If boron neutron capture therapy is to become a clinically useful method of radiation therapy for human malignant melanoma, the boron carrier must be capable of delivering useful amounts of boron to remote tumor sites (metastases) and to poorly pigmented melanomas. The authors have now determined the ability of BPA to accumulate in several nonpigmented melanoma models including human melanoma xenografts in nude mice. The absolute amount of boron in the nonpigmented melanomas was about 50% of the observed in the pigmented counterparts but was still selectively concentrated in the tumor relative to normal tissues in amounts sufficient for effective neutron capture therapy. Single intragastric doses of BPA resulted in selective localization of boron in the amelanotic Greene melanoma carried in the anterior chamber of the rabbit eye and in a pigmented murine melanoma growing in the lungs. The ratio of the boron concentration in these tumors to the boron concentration in the immediately adjacent normal tissue was in the range of 3:1 to 4:1. These distribution studies support the proposal that boron neutron capture therapy may be useful as a regional therapy for malignant melanoma.

  19. Feasibility of using prompt neutron capture gamma rays to detect mercury

    SciTech Connect

    Bell, Z.W.

    1993-10-01

    This report describes a study to determine the feasibility to use neutrons to probe hidden spaces within buildings for the presence of mercury. The study was performed in four phases: First a search of the scientific literature was performed to ascertain the behavior of mercury subsequent to the capture of a thermal or near-thermal neutron. Second, a Monte Carlo investigation (using the code MCNP) of the effects of neutrons on materials expected to be found near and/or surrounding the mercury was undertaken. Third, a Monte Carlo study of the shielding and beam forming properties of various configurations of moderator material was started. Lastly, a Monte Carlo analysis of a likely field situation involving mercury behind 1 inch and 2 inch thicknesses of concrete was performed.

  20. Neutron beam filters for gadolinium capture therapy dosimetry measurements at a TRIGA reactor

    SciTech Connect

    Wehring, B.W.; Uenlue, K.; Cheng, K.P.; Vega-Carillo, H. ); Izewska, J.; Horton, J. )

    1993-01-01

    Neutron capture therapy (NCT) is a modality that employs thermal or epithermal neutron irradiation in conjunction with neutron-absorbing drugs to create localized radiation damage. It has shown promise in the treatment of some malignant tumors of the human central nervous system. The underlying basis for NCT is to provide a highly localized destruction of tumor cells while causing little damage to the healthy cells in the vicinity of the tumor. Boron-10 is the material most often suggested for use as an NCT agent because of its large thermal absorption cross section and short-range reaction products. Considerable research on the chemistry, pharmacology, and toxicology or boron-containing drugs for NCT is in progress.

  1. Power Burst Facility/Boron Neutron Capture Therapy Program for Cancer Treatment: Volume 4, No. 4

    SciTech Connect

    Ackermann, A.L.; Dorn, R.V. III.

    1990-04-01

    Highlights of the Power Burst Facility Boron Neutron Capture Therapy (PBF/BNCT) Program during April 1990 include progress within the areas of: gross boron analysis in tissue, blood, and urine; analytical methodologies development for BSH (Borocaptate Sodium) purity determination; noninvasive boron quantitative determination; operator training was conducted and pharmacokinetic data obtained using a laboratory dog; dosimetry development continues on real-time neutron and gamma monitoring to provide treatment control capability; analytical radiation transport and interaction modeling for BNCT; large animal model studies; neutron source and facility preparation -- PBF upgrades, required for environmental, safety, and OSHA compliance, continue; administration and common support; and PBF operations -- training, safety, and preventive maintenance activities continue. 3 figs.

  2. DNA double-strand break induction in Ku80-deficient CHO cells following Boron Neutron Capture Reaction

    PubMed Central

    2011-01-01

    Background Boron neutron capture reaction (BNCR) is based on irradiation of tumors after accumulation of boron compound. 10B captures neutrons and produces an alpha (4He) particle and a recoiled lithium nucleus (7Li). These particles have the characteristics of high linear energy transfer (LET) radiation and have marked biological effects. The purpose of this study is to verify that BNCR will increase cell killing and slow disappearance of repair protein-related foci to a greater extent in DNA repair-deficient cells than in wild-type cells. Methods Chinese hamster ovary (CHO-K1) cells and a DNA double-strand break (DSB) repair deficient mutant derivative, xrs-5 (Ku80 deficient CHO mutant cells), were irradiated by thermal neutrons. The quantity of DNA-DSBs following BNCR was evaluated by measuring the phosphorylation of histone protein H2AX (gamma-H2AX) and 53BP1 foci using immunofluorescence intensity. Results Two hours after neutron irradiation, the number of gamma-H2AX and 53BP1 foci in the CHO-K1 cells was decreased to 36.5-42.8% of the levels seen 30 min after irradiation. In contrast, two hours after irradiation, foci levels in the xrs-5 cells were 58.4-69.5% of those observed 30 min after irradiation. The number of gamma-H2AX foci in xrs-5 cells at 60-120 min after BNCT correlated with the cell killing effect of BNCR. However, in CHO-K1 cells, the RBE (relative biological effectiveness) estimated by the number of foci following BNCR was increased depending on the repair time and was not always correlated with the RBE of cytotoxicity. Conclusion Mutant xrs-5 cells show extreme sensitivity to ionizing radiation, because xrs-5 cells lack functional Ku-protein. Our results suggest that the DNA-DSBs induced by BNCR were not well repaired in the Ku80 deficient cells. The RBE following BNCR of radio-sensitive mutant cells was not increased but was lower than that of radio-resistant cells. These results suggest that gamma-ray resistant cells have an advantage over gamma-ray sensitive cells in BNCR. PMID:21888676

  3. Low-energy neutron direct capture by {sup 12}C in a dispersive optical potential

    SciTech Connect

    Kitazawa, H.; Go, K.; Igashira, M.

    1998-01-01

    A dispersive optical potential for the interaction between low-energy neutrons and {sup 12}C nuclei is derived from a dispersion relation based on the Feshbach generalized optical model. The potential reproduces completely neutron total cross sections below 1.0 MeV and substantially reproduces the energy of the 3090keV(1/2{sup +}) level in {sup 13}C which is of nearly pure 2s{sub 1/2} single-particle character. It is found that direct-capture model calculations with this potential explain quite successfully the observed off-resonance capture transitions to the ground (1/2{sup {minus}}), 3090keV(1/2{sup +}), 3685keV(3/2{sup {minus}}), and 3854keV(5/2{sup +}) levels in {sup 13}C at neutron energies of 20{endash}600 keV. Special emphasis is laid on the fact that in these model analyses, account should be taken of the spatial nonlocality of the neutron-nucleus interaction potential, in particular for negative energies. {copyright} {ital 1998} {ital The American Physical Society}

  4. In-phantom neutron fluence measurements in the orthogonal Birmingham boron neutron capture therapy beam.

    PubMed

    Tattam, D A; Allen, D A; Beynon, T D; Constantine, G; Green, S; Scott, M C; Weaver, D R

    1998-10-01

    This paper presents the results of an experimental investigation into the performance of the Birmingham accelerator-based epithermal BNCT beam. In-phantom gold foil activation and boron trifluoride tube measurements have been used. The results have been compared with calculated response rates using Monte Carlo modeling of the entire neutron system from source to phantom and detector. The excellent agreement obtained gives us confidence in the validity of the simulations and our ability to predict accurately the neutronic performance of our BNCT facility. PMID:9800704

  5. Astrophysical reaction rates for {sup 58,60}Ni(n,{gamma}) from new neutron capture cross section measurements

    SciTech Connect

    Guber, K. H.; Derrien, H.; Leal, L. C.; Arbanas, G.; Wiarda, D.; Koehler, P. E.; Harvey, J. A.

    2010-11-15

    New neutron capture cross sections of {sup 58,60}Ni were measured in the energy range from 100 eV to 600 keV using the Oak Ridge Electron Linear Accelerator. The combination of these new neutron capture data with previous transmission data allowed a resonance analysis up to 900 keV using R-matrix theory. The theoretically determined direct capture cross sections were included in the analyses. From these resonance parameters and the direct capture contribution, new (n,{gamma}) astrophysical reaction rates were determined over the entire energy range needed by the latest stellar models describing the so-called weak s process.

  6. One-arm spiral instability in hypermassive neutron stars formed by dynamical-capture binary neutron star mergers

    NASA Astrophysics Data System (ADS)

    Paschalidis, Vasileios; East, William E.; Pretorius, Frans; Shapiro, Stuart L.

    2015-12-01

    Using general-relativistic hydrodynamical simulations, we show that merging binary neutron stars can form hypermassive neutrons stars that undergo the one-arm spiral instability. We study the particular case of a dynamical capture merger where the stars have a small spin, as may arise in globular clusters, and focus on an equal-mass scenario where the spins are aligned with the orbital angular momentum. We find that this instability develops when postmerger fluid vortices lead to the generation of a toroidal remnanta configuration whose maximum density occurs in a ring around the center-of-masswith high vorticity along its rotation axis. The instability quickly saturates on a time scale of 10 ms , with the m =1 azimuthal density multipole mode dominating over higher modes. The instability also leaves a characteristic imprint on the postmerger gravitational wave signal that could be detectable if the instability persists in long-lived remnants.

  7. The de-excited energy of electron capture in accreting neutron star crusts

    NASA Astrophysics Data System (ADS)

    Zhang, Jie

    2015-09-01

    When a daughter nucleus produced by electron capture takes part in a level transition from an excited state to its ground state in accreting neutron star crusts, thermal energy will be released and heat the crust, increasing crust temperature and changing subsequent carbon ignition conditions. Previous studies show that the theoretical carbon ignition depth is deeper than the value inferred from observations because the thermal energy is not sufficient. In this paper, we present the de-excited energy from electron capture of rp-process ash before carbon ignition, especially for the initial evolution stage of rp-process ash, by using a level-to-level transition method. We find the theoretical column density of carbon ignition in the resulting superbursts and compare it with observations. The calculation of the electron capture process is based on a more reliable level-to-level transition, adopting new data from experiments or theoretical models (e.g., large-scale shell model and proton-neutron quasi-particle random phase approximation). The new carbon ignition depth is estimated by fitting from previous results of a nuclear reaction network. Our results show the average de-excited energy from electron capture before carbon ignition is ?0.026 MeV/u, which is significantly larger than the previous results. This energy is beneficial for enhancing the crust's temperature and decreasing the carbon ignition depth of superbursts.

  8. Radiative Capture of Neutrons and Deuterons Into CARBON-13: Evidence for a Secondary Doorway State Effect

    NASA Astrophysics Data System (ADS)

    August, Robert Andrew, Jr.

    Differential cross sections were measured at a detector angle of 90(DEGREES) in the lab for the ('12)C(n,(gamma)(,0))('13)C reaction at 19 incident neutron energies between 6.5 and 18.5 MeV. This energy region spans the pygmy and T(,<) giant dipole resonances in ('13)C. Angular distributions of cross section were measured for this reaction at 7 incident neutron energies between 12.0 and 18.5 MeV. Angular distributions of vector analyzing power were measured for the ('12)C((')n,(gamma)(,0))('13)C reaction at 4 incident neutron energies between 12.0 and 18.2 MeV, analyzing powers were measured at 125(DEGREES) neutron energies of 15.4, 17.4, and 18.8 MeV. The angular distributions show a rapid energy dependence just below the peak of the giant dipole resonance. This energy dependent structure in the angular distributions occurs at the same excitation energy as a resonance in the ('11)B(d,(gamma)(,0))('13)C reaction. A study of the deuteron capture reaction in this energy region was therefore under- taken. The 90(DEGREES) differential cross sections were measured for the ('11)B(d,(gamma)(,0))('13)C reaction at 11 deuteron beam energies between 1.65 and 3.50 MeV. Angular distributions of cross section were measured at deuteron beam energies of 1.6, 1.8, 2.0, and 4.0 MeV. Angular distributions of vector and tensor (T(,20)((THETA))) analyzing power were measured at deuteron beam energies of 2.0 and 4.0 MeV, with 55(DEGREES) and 125(DEGREES) vector analyzing powers being measured at 1.6 and 1.8 MeV. Both data sets were fit simultaneously using a formalism which described the ('11)B(d,(gamma)(,0))('13)C resonance as a secondary doorway state, with the T(,<) giant dipole resonance (seen through the neutron capture data) being a primary doorway state. The data were well described by this fit, most notably the rapid energy dependence in the neutron capture angular distributions. A shell model calculation of the expected strength of this interaction agreed well with the strength found by fitting the data. It was found to be possible to describe the deuteron capture angular distributions (the doorway state formalism leaves these independent of the rest of the analysis) fairly well using a simple "deuteron cluster" model of the ('13)C ground state.

  9. An overview of DANCE: a 4II BaF[2] detector for neutron capture measurements at LANSCE.

    SciTech Connect

    Ullmann, J. L.

    2004-01-01

    The Detector for Advanced Neutron Capture experiments (DANCE) is a 162-element, 4{pi} BaF{sub 2} array designed to make neutron capture cross-section measurements on rare or radioactive targets with masses as little as 1 mg. Accurate capture cross sections are needed in many research areas, including stellar nucleosynthesis, advanced nuclear fuel cycles, waste transmutation, and other applied programs. These cross sections are difficult to calculate accurately and must be measured. Up to now, except for a few long-lived nuclides there are essentially no differential capture measurements on radioactive nuclei. The DANCE array is located at the Lujan Neutron Scattering Center at LANSCE, which is a continuous-spectrum neutron source with useable energies from below thermal to about 100 keV. Data acquisition is done with 320 fast waveform digitizers. The design and initial performance results, including background minimization, will be discussed.

  10. Krypton and xenon in Apollo 14 samples - Fission and neutron capture effects in gas-rich samples

    NASA Technical Reports Server (NTRS)

    Drozd, R.; Hohenberg, C.; Morgan, C.

    1975-01-01

    Gas-rich Apollo 14 breccias and trench soil are examined for fission xenon from the decay of the extinct isotopes Pu-244 and I-129, and some samples have been found to have an excess fission component which apparently was incorporated after decay elsewhere and was not produced by in situ decay. Two samples have excess Xe-129 resulting from the decay of I-129. The excess is correlated at low temperatures with excess Xe-128 resulting from neutron capture on I-127. This neutron capture effect is accompanied by related low-temperature excesses of Kr-80 and Kr-82 from neutron capture on the bromine isotopes. Surface correlated concentrations of iodine and bromine are calculated from the neutron capture excesses.

  11. Boron-Containing Compounds for Liposome-Mediated Tumor Localization and Application to Neutron Capture Therapy

    SciTech Connect

    Hawthorne, M. Frederick

    2005-04-07

    Medical application of boron neutron capture therapy (BNCT) has been significantly hindered by the slow development of boron drug-targeting methodologies for the selective delivery of high boron concentration sto malignant cells. We have successfully sought to fill this need by creating liposomes suitable as in vivo boron delivery vehicles for BNCT. Delivery of therapeutic quantities of boron to tumors in murine models has been achieved with small unilamellar boron-rich liposomes. Subsequently, attempts have been made to improve delivery efficiency of liposomes encapsulating boron-containing water-soluble species into their hollow core by incorporating lipophilic boron compounds as addenda to the liposome bilayer, incorporating boron compounds as structural components of the bilayer (which however, poses the risk of sacrificing some stability), and combinations thereof. Regardless of the method, approximately 90% of the total liposome mass remains therapeutically inactive and comprised of the vehicle's construction materials, while less than 5% is boron for neutron targeting. Following this laboratory's intensive study, the observed tumor specificity of certain liposomes has been attributed to their diminutive size of these liposomes (30-150 nm), which enables these small vesicles to pass through the porous, immature vasculature of rapidly growing tumor tissue. We surmised that any amphiphilic nanoparticle of suitable size could possess some tumor selectivity. Consequently, the discovery of a very boron-rich nanoparticle delivery agent with biodistribution performance similar to unilamellar liposomes became one of our goals. Closomers, a new class of polyhedral borane derivatives, attracted us as an alternative BNCT drug-delivery system. We specifically envisioned dodeca (nido-carboranyl)-substituted closomers as possibly having a great potential role in BNCT drug delivery. They could function as extraordinarily boron-rich BNCT drugs since they are amphiphilic unimolecular nanoparticles presenting several advantages: tunable size through functionalization and branching, spherical shape due to the icosahedral B122 core, promising water solubility resulting from degradation of all pendant closo-carborane groups to their hydrophilic nido anion substituents, and efficient boron delivery owing to the presence of 120 boron atoms which gives rise to a boron content as high as 40% by weight. Keeping the new objective in mind, we have focused on the design, synthesis and evaluation of new and very boron-rich closomer species. Additionally, progress has also been made toward the evaluation of a newly synthesized boron-rich lipid as a substitute for DSPC in bilayer construction, and the boron content of the resulting liposomes has been greatly enhanced. Related research involving the synthesis and self-assembly of carborane-containing amphiphiles has been systematically studied. Combined hydrophobic and hydrophilic properties of the single-chain amphiphiles allow their spontaneous self-assembly to form rods under a variety of variable conditions, such as concentration in the bilayer, carborane cage structure, chain-length, counterion identity, solvents, methods of preparation, and the ionic charge. On the other hand, the number of attached chains affects the self-assembly process. Particles having totally different shapes have been observed for dual-chain amphiphiles.

  12. Study of moderator thickness for an accelerator-based neutron irradiation facility for boron neutron capture therapy using the 7Li(p,n) reaction near threshold.

    PubMed

    Zimin, S; Allen, B J

    2000-01-01

    Accelerator neutron sources for epithermal neutron capture therapy utilizing the 7Li(p,n) nuclear reaction will require a moderator even in the threshold range of 1.89 to 1.95 MeV. The corresponding neutron energies allow for a thinner reflector and moderator, with less reduction of the epithermal flux. To estimate the useful neutron flux within the epithermal range (4 eV-40 keV), the optimal thickness of a heavy water moderator was determined using the two-dimensional neutron transport S(N) code DORT. Optimized results are compared with the epithermal fluxes reported for the higher proton energy range, and are found to be inferior. Thus, this study supports the 2.5-3.0 MeV proton energy range for accelerator boron neutron capture therapy. PMID:10661583

  13. Measurements of keV-NEUTRON Capture Cross Section and Gamma-Ray Spectra of 142Nd

    NASA Astrophysics Data System (ADS)

    Katabuchi, T.; Igashira, M.; Tajika, M.; Nakamura, Y.; Kamada, S.; Terada, K.

    2013-03-01

    The neutron capture cross section and capture γ-ray spectra of 142Nd in the neutron energy ranges from 15 to 95 keV, and around 550 keV have been measured by the time-of-flight method. Capture γ-rays were detected with an anti-Compton NaI(Tl) spectrometer, and the pulse-height weighting technique was applied to derive the neutron capture cross section. The capture γ-ray spectra were obtained by unfolding the detector pulse-height spectra with the detector response matrix. The results were compared with previous measurements and cross section data in the evaluated nuclear data libraries, JENDL-4.0 and ENDF/B-VII.0.

  14. A capture-gated neutron calorimeter using plastic scintillators and 3He drift tubes

    SciTech Connect

    Wang, Zhehui; Morris, Christopher L; Spaulding, Randy J; Bacon, Jeffrey D; Borozdin, Konstantin N; Chung, Kiwhan; Clark, Deborah J; Green, Jesse A; Greene, Steven J; Hogan, Gary E; Jason, Andrew; Lisowski, Paul W; Makela, Mark F; Mariam, Fessaha G; Miyadera, Haruo; Murray, Matthew M; Saunders, Alexander; Wysocki, Frederick J; Gray, Frederick E

    2010-01-01

    A segmented neutron calorimeter using nine 4-inch x 4-inch x 48-inch plastic scintillators and sixteen 2-inch-diameter 48-inch-long 200-mbar-{sup 3}He drift tubes is described. The correlated scintillator and neutron-capture events provide a means for n/{gamma} discrimination, critical to the neutron calorimetry when the {gamma} background is substantial and the {gamma} signals are comparable in amplitude to the neutron signals. A single-cell prototype was constructed and tested. It can distinguish between a {sup 17}N source and a {sup 252}Cf source when the {gamma} and the thermal neutron background are sufficiently small. The design and construction of the nine-cell segmented detector assembly follow the same principle. By recording the signals from individual scintillators, additional {gamma}-subtraction schemes, such as through the time-of-flight between two scintillators, may also be used. The variations of the light outputs from different parts of a scintillator bar are less than 10%.

  15. Strong neutrino cooling by cycles of electron capture and β- decay in neutron star crusts.

    PubMed

    Schatz, H; Gupta, S; Möller, P; Beard, M; Brown, E F; Deibel, A T; Gasques, L R; Hix, W R; Keek, L; Lau, R; Steiner, A W; Wiescher, M

    2014-01-01

    The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, β(-) decay, involving neutron-rich nuclei at a typical depth of about 150 metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This 'Urca' mechanism has been studied in the context of white dwarfs and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface. PMID:24291788

  16. 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

  17. Neutron beam optimization for boron neutron capture therapy using the D-D and D-T high-energy neutron sources

    SciTech Connect

    Verbeke, J.M.; Vujic, J.L.; Leung, K.N.

    2000-02-01

    A monoenergetic neutron beam simulation study is carried out to determine the most suitable neutron energy for treatment of shallow and deep-seated brain tumors in the context of boron neutron capture therapy. Two figures-of-merit--the absorbed skin dose and the absorbed tumor dose at a given depth in the brain--are used to measure the neutron beam quality. Based on the results of this study, moderators, reflectors, and delimiters are designed and optimized to moderate the high-energy neutrons from the fusion reactions {sup 2}H(d,n){sup 3}He and {sup 3}H(d,n){sup 4}He down to a suitable energy spectrum. Two different computational models (MCNP and BNCT-RTPE) have been used to study the dose distribution in the brain. With the optimal beam-shaping assembly, a 1-A mixed deuteron/triton beam of energy 150 keV accelerated onto a titanium target leads to a treatment time of 1 h. The dose near the center of the brain obtained with this configuration is > 65% higher than the dose from a typical spectrum produced by the Brookhaven Medical Research Reactor and is comparable to the dose obtained by other accelerator-produced neutron beams.

  18. Galactic evolution of rapid neutron capture process abundances: the inhomogeneous approach

    NASA Astrophysics Data System (ADS)

    Wehmeyer, B.; Pignatari, M.; Thielemann, F.-K.

    2015-09-01

    For the origin of heavy rapid neutron capture process (r-process) elements, different sources have been proposed, e.g. core-collapse supernovae or neutron star mergers. Old metal-poor stars carry the signature of the astrophysical source(s). Among the elements dominantly made by the r-process, europium (Eu) is relatively easy to observe. In this work we simulate the evolution of Eu in our Galaxy with the inhomogeneous chemical evolution (ICE) model, and compare our results with spectroscopic observations. We test the most important parameters affecting the chemical evolution of Eu: (a) for neutron star mergers the coalescence time-scale of the merger (tcoal) and the probability to experience a neutron star merger event after two supernova explosions occurred and formed a double neutron star system (PNSM) and (b) for the subclass of magnetorotationally driven supernovae (`Jet-SNe'), their occurrence rate compared to standard supernovae (PJet-SN). We find that the observed [Eu/Fe] pattern in the Galaxy can be reproduced by a combination of neutron star mergers and Jet-SNe as r-process sources. While neutron star mergers alone seem to set in at too high metallicities, Jet-SNe provide a cure for this deficiency at low metallicities. Furthermore, we confirm that local inhomogeneities can explain the observed large spread in the Eu abundances at low metallicities. We also predict the evolution of [O/Fe] to test whether the spread in α-elements for inhomogeneous models agrees with observations and whether this provides constraints on supernova explosion models and their nucleosynthesis.

  19. Optimization of Boron Neutron Capture Therapy for the Treatment of Undifferentiated Thyroid Cancer

    SciTech Connect

    Dagrosa, Maria Alejandra; Thomasz, Lisa M.Sc.; Longhino, Juan; Perona, Marina; Calzetta, Osvaldo; Blaumann, Herman; Rebagliati, Raul Jimenez; Cabrini, Romulo; Kahl, Steven; Juvenal, Guillermo Juan; Pisarev, Mario Alberto

    2007-11-15

    Purpose: To analyze the possible increase in efficacy of boron neutron capture therapy (BNCT) for undifferentiated thyroid carcinoma (UTC) by using p-boronophenylalanine (BPA) plus 2,4-bis ({alpha},{beta}-dihydroxyethyl)-deutero-porphyrin IX (BOPP) and BPA plus nicotinamide (NA) as a radiosensitizer of the BNCT reaction. Methods and Materials: Nude mice were transplanted with a human UTC cell line (ARO), and after 15 days they were treated as follows: (1) control, (2) NCT (neutrons alone), (3) NCT plus NA (100 mg/kg body weight [bw]/day for 3 days), (4) BPA (350 mg/kg bw) + neutrons, (5) BPA + NA + neutrons, and (6) BPA + BOPP (60 mg/kg bw) + neutrons. The flux of the mixed (thermal + epithermal) neutron beam was 2.8 x 10{sup 8} n/cm{sup 2}/sec for 83.4 min. Results: Neutrons alone or with NA caused some tumor growth delay, whereas in the BPA, BPA + NA, and BPA + BOPP groups a 100% halt of tumor growth was observed in all mice at 26 days after irradiation. When the initial tumor volume was 50 mm{sup 3} or less, complete remission was found with BPA + NA (2 of 2 mice), BPA (1 of 4), and BPA + BOPP (7 of 7). After 90 days of complete regression, recurrence of the tumor was observed in BPA + NA (2 of 2) and BPA + BOPP (1 of 7). The determination of apoptosis in tumor samples by measurements of caspase-3 activity showed an increase in the BNCT (BPA + NA) group at 24 h (p < 0.05 vs. controls) and after the first week after irradiation in the three BNCT groups. Terminal transferase dUTP nick end labeling analysis confirmed these results. Conclusions: Although NA combined with BPA showed an increase of apoptosis at early times, only the group irradiated after the combined administration of BPA and BOPP showed a significantly improved therapeutic response.

  20. DNA damage induced by boron neutron capture therapy is partially repaired by DNA ligase IV.

    PubMed

    Kondo, Natsuko; Sakurai, Yoshinori; Hirota, Yuki; Tanaka, Hiroki; Watanabe, Tsubasa; Nakagawa, Yosuke; Narabayashi, Masaru; Kinashi, Yuko; Miyatake, Shin-Ichi; Hasegawa, Masatoshi; Suzuki, Minoru; Masunaga, Shin-Ichiro; Ohnishi, Takeo; Ono, Koji

    2016-03-01

    Boron neutron capture therapy (BNCT) is a particle radiation therapy that involves the use of a thermal or epithermal neutron beam in combination with a boron ((10)B)-containing compound that specifically accumulates in tumor. (10)B captures neutrons and the resultant fission reaction produces an alpha ((4)He) particle and a recoiled lithium nucleus ((7)Li). These particles have the characteristics of high linear energy transfer (LET) radiation and therefore have marked biological effects. High-LET radiation is a potent inducer of DNA damage, specifically of DNA double-strand breaks (DSBs). The aim of the present study was to clarify the role of DNA ligase IV, a key player in the non-homologous end-joining repair pathway, in the repair of BNCT-induced DSBs. We analyzed the cellular sensitivity of the mouse embryonic fibroblast cell lines Lig4-/- p53-/- and Lig4+/+ p53-/- to irradiation using a thermal neutron beam in the presence or absence of (10)B-para-boronophenylalanine (BPA). The Lig4-/- p53-/- cell line had a higher sensitivity than the Lig4+/+ p53-/-cell line to irradiation with the beam alone or the beam in combination with BPA. In BNCT (with BPA), both cell lines exhibited a reduction of the 50% survival dose (D 50) by a factor of 1.4 compared with gamma-ray and neutron mixed beam (without BPA). Although it was found that (10)B uptake was higher in the Lig4+/+ p53-/- than in the Lig4-/- p53-/- cell line, the latter showed higher sensitivity than the former, even when compared at an equivalent (10)B concentration. These results indicate that BNCT-induced DNA damage is partially repaired using DNA ligase IV. PMID:26573366

  1. Simultaneous measurement of neutron-induced capture and fission reactions at CERN

    NASA Astrophysics Data System (ADS)

    Guerrero, C.; Berthoumieux, E.; Cano-Ott, D.; Mendoza, E.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bcares, V.; Be?v?, F.; Belloni, F.; Billowes, J.; Brugger, M.; Calviani, M.; Calvio, F.; Carrapio, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Corts, G.; Corts-Giraldo, M. A.; Diakaki, M.; Dillmann, I.; Domingo-Pardo, C.; Duran, I.; Eleftheriadis, C.; Fernndez-Ordez, M.; Ferrari, A.; Ganesan, S.; Giubrone, G.; Gmez-Hornillos, M. B.; Gonalves, I. F.; Gonzlez-Romero, E.; Gramegna, F.; Griesmayer, E.; Gunsing, F.; Jenkins, D.; Jericha, E.; Kadi, Y.; Kppeler, F.; Karadimos, D.; Kroll, J.; Krti?ka, M.; Lebbos, E.; Lederer, C.; Leeb, H.; Losito, R.; Lozano, M.; Manousos, A.; Marganiec, J.; Marrone, S.; Martinez, T.; Massimi, C.; Mastinu, P. F.; Meaze, M.; Mengoni, A.; Milazzo, P. M.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plag, R.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Roman, F.; Rubbia, C.; Sarmento, R.; Tagliente, G.; Tain, J. L.; Tarro, D.; Tassan-Got, L.; Tsinganis, A.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vermeullen, M.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Wei, C.; Wright, T.

    2012-03-01

    The measurement of the capture cross-section of fissile elements, of utmost importance for the design of innovative nuclear reactors and the management of nuclear waste, faces particular difficulties related to the ? -ray background generated in the competing fission reactions. At the CERN neutron time-of-flight facility n_TOF we have combined the Total Absorption Calorimeter (TAC) capture detector with a set of three 235U loaded MicroMegas (MGAS) fission detectors for measuring simultaneously two reactions: capture and fission. The results presented here include the determination of the three detection efficiencies involved in the process: ensuremath \\varepsilon_{TAC}(n,f) , ensuremath \\varepsilon_{TAC}(n,?) and ensuremath \\varepsilon_{MGAS}(n,f) . In the test measurement we have succeeded in measuring simultaneously with a high total efficiency the 235U capture and fission cross-sections, disentangling accurately the two types of reactions. The work presented here proves that accurate capture cross-section measurements of fissile isotopes are feasible at n_TOF.

  2. Neutron capture and total cross sections of {sup 127}I and {sup 129}I

    SciTech Connect

    Noguere, G.; Bouland, O.; Brusegan, A.; Schillebeeckx, P.; Siegler, P.; Lepre circumflex tre, A.; Herault, N.; Rudolf, G.

    2006-11-15

    High-resolution transmission and capture time-of-flight measurements of {sup 127}I and {sup 129}I have been carried out at the 150 MeV pulsed neutron source at the Geel electron linear accelerator (GELINA) facility of the Institute for Reference Materials and Measurements. Below 10 keV, the individual resonances were analyzed with the Reich-Moore approximation of the R-matrix theory. The resonance parameters (energy and partial widths) and the potential scattering length R{sub 0}{sup '} were determined using the resonance shape analysis technique. Within the 3.5-100 keV neutron energy range, the capture and total cross sections were interpreted in terms of average resonance parameters with the Hauser-Feshbach formalism with width fluctuations. This work has delivered a consistent set of {sup 127,129}I s- and p-wave average resonance parameters (neutron strength function S{sub l}, mean level spacing D{sub l}, and average radiation width <{gamma}{gamma}{sub 1}>.

  3. Development of a Method of Thermal-Neutron Capture Cross Section Measurement by Unfolding Prompt Gamma-Ray Spectra

    SciTech Connect

    Sakane, Hitoshi; Furutaka, Kazuyoshi; Shcherbakov, Oleg; Harada, Hideo; Fujii, Toshiyuki; Yamana, Hajimu

    2005-05-24

    A method of thermal neutron-capture cross-section measurement by using a pair spectrometer and unfolding prompt gamma-ray spectra is described. To evaluate the validity of the method, it was applied for the measurement of the thermal neutron cross section of 14N. A pair spectrometer system was used to measure prompt gamma rays emitted from 15N produced by thermal neutron capture. Response functions of the system were calculated by using EGS-4 code. To verify the reproducibility of the response functions, the measured spectrum of prompt gamma rays of 15N was reproduced by using EGS-4 code, which was used for calculating response functions.

  4. Comparison of Snyder Head Phantom Models Used for Neutron Capture Therapy Benchmark Monte Carlo Dosimetry Calculations

    NASA Astrophysics Data System (ADS)

    Goorley, T.; Kiger, W. S.; Zamenhof, R.

    As Boron Neutron Capture Therapy (BNCT) clinical trials are initiated in more countries, new treatment planning software programs are being developed to calculate dose distributions in patient specific models. A reference suite of test problems, i.e., head phantom irradiations and resulting depth-dose curves, would allow quantitative comparison of the treatment planning software. This paper presents sets of central axis depth vs. dose curves calculated with the Monte Carlo radiation transport code MCNP4B for five different representations of the Snyder head phantom. The first is a multi-shell analytic ellipsoidal representation, and the remaining four are voxelized representations with cube edge lengths of 16, 10, 8 and 4 mm. For these calculations, 10 cm diameter monoenergetic and monodirectional neutron and photon beams were incident along the central axes of the models. Individual beams of 0.0253 eV, 1, 2, 10, 100 and 1000 keV neutrons, and 0.2, 0.5, 1, 2, 5, and 10 MeV photons were simulated to high statistical convergence, with statistical error less than 1% in the center of the model. A "generic" epithermal neutron beam, with 1% fast flux contamination and 10% thermal flux contamination, similar to those proposed for BNCT treatments, was also simulated with all five models. Computations for both of the smaller sized voxel models produced thermal neutron, fast neutron, and gamma dose rates within 4% of those from the analytical representation. It is proposed that these data sets be used by the BNCT community for the verification of existing and new BNCT treatment planning software.

  5. Experimental assessment of the performance of a proposed lead slowing-down spectrometer at WNR/PSR (Weapons Neutron Research/Proton Storage Ring)

    SciTech Connect

    Moore, M.S.; Koehler, P.E.; Michaudon, A.; Schelberg, A. ); Danon, Y.; Block, R.C.; Slovacek, R.E. ); Hoff, R.W.; Lougheed, R.W. )

    1990-01-01

    In November 1989, we carried out a measurement of the fission cross section of {sup 247}Cm, {sup 250}Cf, and {sup 254}Es on the Rensselaer Intense Neutron Source (RINS) at Rensselaer Polytechnic Institute (RPI). In July 1990, we carried out a second measurement, using the same fission chamber and electronics, in beam geometry at the Los Alamos Neutron Scattering Center (LANSCE) facility. Using the relative count rates observed in the two experiments, and the flux-enhancement factors determined by the RPI group for a lead slowing-down spectrometer compared to beam geometry, we can assess the performance of a spectrometer similar to RINS, driven by the Proton Storage Ring (PSR) at the Los Alamos National Laboratory. With such a spectrometer, we find that is is feasible to make measurements with samples of 1 ng for fission 1 {mu}g for capture, and of isotopes with half-lives of tens of minutes. It is important to note that, while a significant amount of information can be obtained from the low resolution RINS measurement, a definitive determination of average properties, including the level density, requires that the resonance structure be resolved. 12 refs., 5 figs., 3 tabs.

  6. Technical aspects of boron neutron capture therapy at the BNL Medical Research Reactor

    SciTech Connect

    Holden, N.E.; Rorer, D.C.; Patti, F.J.; Liu, H.B.; Reciniello, R.; Chanana, A.D.

    1997-07-01

    The Brookhaven Medical Research Reactor, BMRR, is a 3 MW heterogeneous, tank-type, light water cooled and moderated, graphite reflected reactor, which was designed for biomedical studies. Early BNL work in Boron Neutron Capture Therapy (BNCT) used a beam of thermal neutrons for experimental treatment of brain tumors. Research elsewhere and at BNL indicated that higher energy neutrons would be required to treat deep seated brain tumors. Epithermal neutrons would be thermalized as they penetrated the brain and peak thermal neutron flux densities would occur at the depth of brain tumors. One of the two BMRR thermal port shutters was modified in 1988 to include plates of aluminum and aluminum oxide to provide an epithermal port. Lithium carbonate in polyethylene was added in 1991 around the bismuth port to reduce the neutron flux density coming from outside the port. To enhance the epithermal neutron flux density, the two vertical thimbles A-3 (core edge) and E-3 (in core) were replaced with fuel elements. There are now four fuel elements of 190 grams each and 28 fuel elements of 140 grams each for a total of 4.68 kg of {sup 235}U in the core. The authors have proposed replacing the epithermal shutter with a fission converter plate shutter. It is estimated that the new shutter would increase the epithermal neutron flux density by a factor of seven and the epithermal/fast neutron ratio by a factor of two. The modifications made to the BMRR in the past few years permit BNCT for brain tumors without the need to reflect scalp and bone flaps. Radiation workers are monitored via a TLD badge and a self-reading dosimeter during each experiment. An early concern was raised about whether workers would be subject to a significant dose rate from working with patients who have been irradiated. The gamma ray doses for the representative key personnel involved in the care of the first 12 patients receiving BNCT are listed. These workers did not receive unusually high exposures.

  7. A Nuclear Data Project on Neutron Capture Cross Sections of Long-Lived Fission Products and Minor Actinides

    NASA Astrophysics Data System (ADS)

    Igashira, M.; Katabuchi, T.; Harada, H.; Nakamura, S.; Kimura, A.; Iwamoto, N.; Hori, J.; Kiyanagi, Y.

    2014-04-01

    A nuclear data project entitled "Systematic Study on Neutron Capture Reaction Cross Sections for the Technological Development of Nuclear Transmutation of Long-Lived Nuclear Wastes" is being performed. The objective of the project is to improve nuclear data libraries, by making the precise measurements of neutron capture cross sections of Long-Lived Nuclear Wastes (LLNWs), analyzing the measured results theoretically, and supplying reliable calculated capture cross sections for the LLNWs. This contribution presents the outline of the project, and individual results are presented by other contributions.

  8. Scissors Mode of 162 Dy Studied from Resonance Neutron Capture

    SciTech Connect

    Baramsai, B.; Bečvář, F.; Bredeweg, T. A.; Haight, R. C.; Jandel, M.; Kroll, J.; Krtička, M.; Mitchell, G. E.; O’Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Valenta, S.; Wilhelmy, J. B.

    2015-05-28

    Multi-step cascade γ-ray spectra from the neutron capture at isolated resonances of 161Dy nucleus were measured at the LANSCE/DANCE time-of-flight facility in Los Alamos National Laboratory. The objectives of this experiment were to confirm and possibly extend the spin assignment of s-wave neutron resonances and get new information on photon strength functions with emphasis on the role of the M1 scissors mode vibration. The preliminary results show that the scissors mode plays a significant role in all transitions between accessible states of the studied nucleus. The photon strength functions describing well our data are compared to results from 3He-induced reactions, (n,γ) experiments on Gd isotopes, and (γ,γ’) reactions.

  9. Ultrananopores in Carbons by Boron-neutron Capture and Their Effect on Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Romanos, J.; Robertson, D.; Beckner, M.; Kraus, M.; Kuchta, B.; Firlej, L.; Pfeifer, P.

    2010-03-01

    The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has been optimizing high surface area activated carbon nanospaces for high capacity hydrogen storage. Boron doped samples have been prepared by vapor deposition of decaborane. Neutron irradiation of Boron doped activated carbon was done at the University of Missouri Research Reactor (MURR). Ultrananopores created by alpha particle fission tracks from Boron-neutron capture alter the surface and the adsorption properties of activated Carbons. A detailed theoretical model of the creation and the structure of defects on graphene sheets was developed. BET surface areas, porosity, and pores size distributions of modified activated carbons were measured using sub-critical nitrogen isotherms. Hydrogen adsorption isotherms of irradiated samples were indicative of record fraction of high binding energies and record fraction of sub-nm pores compared to their unirradiated parent samples.

  10. Neutron capture surrogate reaction on 75As in inverse kinematics using (d,p )

    SciTech Connect

    Peters, W. A.; Cizewski, J. A.; Hatarik, Robert; O'Malley, Patrick; Jones, K. L.; Schmitt, Kyle; Moazen, Brian; Chae, K. Y.; Pittman, S. T.; Kozub, R. L.; Vieira, D. J.; Jandel, M.; Wilhelmy, J. B.; Matei, Catalin; Escher, J.; Bardayan, Daniel W; Pain, Steven D; Smith, Michael Scott

    2010-01-01

    The 75As(d,p ) reaction in inverse kinematics as a surrogate for neutron capture was performed at Oak Ridge National Laboratory using a deuterated plastic target. The intensity of the 165 keV -ray from 76As in coincidence with ejected protons, from exciting 76As above the neutron separation energy populating a compound state, was measured. A tight geometry of four segmented germanium clover -ray detectors together with eight ORRUBA-type silicon-strip charged-particle detectors were used to optimize geometric acceptance. The preliminary analysis of the 75As experiment and the ecacy and future plans of the (d,p ) surrogate campaign in inverse kinematics are discussed.

  11. Carboranyl amino acids for site specific neutron capture therapy of malignant melanoma

    SciTech Connect

    Kahl, S.B.

    1991-01-01

    The single most difficult problem yet to be solved for effective clinical use of boron neutron capture therapy (BNCT) in the United States is the development of highly tumor-selective third generation boron compounds. In this context, the boronated amino acids and peptides would be a significant step toward this goal. Our preliminary in vitro finding that carboranylalanine is a highly potent neutron sensitizer strongly suggests that this amino acid is a most desirable third generation compound, and our development of both chiral and achiral synthesis for its production are a necessary prerequisite for advancement of the field in this area. We further believe that insertion of this amino acid into carefully selected peptides will provide substances able to a target a much wider variety of malignancies than just melanoma. It seems clear that further investigations into this promising field are warranted if BNCT is to achieve clinical acceptability.

  12. Carboranyl amino acids for site specific neutron capture therapy of malignant melanoma

    SciTech Connect

    Kahl, S.B.

    1991-12-31

    The single most difficult problem yet to be solved for effective clinical use of boron neutron capture therapy (BNCT) in the United States is the development of highly tumor-selective third generation boron compounds. In this context, the boronated amino acids and peptides would be a significant step toward this goal. Our preliminary in vitro finding that carboranylalanine is a highly potent neutron sensitizer strongly suggests that this amino acid is a most desirable third generation compound, and our development of both chiral and achiral synthesis for its production are a necessary prerequisite for advancement of the field in this area. We further believe that insertion of this amino acid into carefully selected peptides will provide substances able to a target a much wider variety of malignancies than just melanoma. It seems clear that further investigations into this promising field are warranted if BNCT is to achieve clinical acceptability.

  13. Boron analysis for neutron capture therapy using particle-induced gamma-ray emission.

    PubMed

    Nakai, Kei; Yamamoto, Yohei; Okamoto, Emiko; Yamamoto, Tetsuya; Yoshida, Fumiyo; Matsumura, Akira; Yamada, Naoto; Kitamura, Akane; Koka, Masashi; Satoh, Takahiro

    2015-12-01

    The neutron source of BNCT is currently changing from reactor to accelerator, but peripheral facilities such as a dose-planning system and blood boron analysis have still not been established. To evaluate the potential application of particle-induced gamma-ray emission (PIGE) for boron measurement in clinical boron neutron capture therapy, boronophenylalanine dissolved within a cell culture medium was measured using PIGE. PIGE detected 18?gB/mL f-BPA in the culture medium, and all measurements of any given sample were taken within 20min. Two hours of f-BPA exposure was required to create a boron distribution image. However, even though boron remained in the cells, the boron on the cell membrane could not be distinguished from the boron in the cytoplasm. PMID:26242558

  14. Boron Neutron Capture Therapy (BNCT) Dose Calculation using Geometrical Factors Spherical Interface for Glioblastoma Multiforme

    SciTech Connect

    Zasneda, Sabriani; Widita, Rena

    2010-06-22

    Boron Neutron Capture Therapy (BNCT) is a cancer therapy by utilizing thermal neutron to produce alpha particles and lithium nuclei. The superiority of BNCT is that the radiation effects could be limited only for the tumor cells. BNCT radiation dose depends on the distribution of boron in the tumor. Absorbed dose to the cells from the reaction 10B (n, {alpha}) 7Li was calculated near interface medium containing boron and boron-free region. The method considers the contribution of the alpha particle and recoiled lithium particle to the absorbed dose and the variation of Linear Energy Transfer (LET) charged particles energy. Geometrical factor data of boron distribution for the spherical surface is used to calculate the energy absorbed in the tumor cells, brain and scalp for case Glioblastoma Multiforme. The result shows that the optimal dose in tumor is obtained for boron concentrations of 22.1 mg {sup 10}B/g blood.

  15. Neutron capture cross section of unstable 63Ni: implications for stellar nucleosynthesis.

    PubMed

    Lederer, C; Massimi, C; Altstadt, S; Andrzejewski, J; Audouin, L; Barbagallo, M; Bécares, V; Bečvář, F; Belloni, F; Berthoumieux, E; Billowes, J; Boccone, V; Bosnar, D; Brugger, M; Calviani, M; Calviño, F; Cano-Ott, D; Carrapiço, C; Cerutti, F; Chiaveri, E; Chin, M; Colonna, N; Cortés, G; Cortés-Giraldo, M A; Diakaki, M; Domingo-Pardo, C; Duran, I; Dressler, R; Dzysiuk, N; Eleftheriadis, C; Ferrari, A; Fraval, K; Ganesan, S; García, A R; Giubrone, G; Gómez-Hornillos, M B; Gonçalves, I F; González-Romero, E; Griesmayer, E; Guerrero, C; Gunsing, F; Gurusamy, P; Jenkins, D G; Jericha, E; Kadi, Y; Käppeler, F; Karadimos, D; Kivel, N; Koehler, P; Kokkoris, M; Korschinek, G; Krtička, M; Kroll, J; Langer, C; Leeb, H; Leong, L S; Losito, R; Manousos, A; Marganiec, J; Martínez, T; Mastinu, P F; Mastromarco, M; Meaze, M; Mendoza, E; Mengoni, A; Milazzo, P M; Mingrone, F; Mirea, M; Mondelaers, W; Paradela, C; Pavlik, A; Perkowski, J; Pignatari, M; Plompen, A; Praena, J; Quesada, J M; Rauscher, T; Reifarth, R; Riego, A; Roman, F; Rubbia, C; Sarmento, R; Schillebeeckx, P; Schmidt, S; Schumann, D; Tagliente, G; Tain, J L; Tarrío, D; Tassan-Got, L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Ventura, A; Versaci, R; Vermeulen, M J; Vlachoudis, V; Vlastou, R; Wallner, A; Ware, T; Weigand, M; Weiß, C; Wright, T J; Zugec, P

    2013-01-11

    The 63Ni(n,γ) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from   kT=5-100  keV with uncertainties around 20%. Stellar model calculations for a 25M⊙ star show that the new data have a significant effect on the s-process production of 63Cu, 64Ni, and 64Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova. PMID:23383895

  16. Neutron Capture Surrogate Reaction on 75As in Inverse Kinematics Using (d,p(gamma))

    SciTech Connect

    Peters, W A; Cizewski, J A; Hatarik, R; O?Malley, P D; Jones, K L; Schmitt, K; Moazen, B H; Chae, K Y; Pittman, S T; Kozub, R L; Vieira, D; Jandel, M; Wilhelmy, J B; Matei, C; Escher, J; Bardayan, D W; Pain, S D; Smith, M S

    2009-11-09

    The {sup 75}As(d,p{gamma}) reaction in inverse kinematics as a surrogate for neutron capture was performed at Oak Ridge National Laboratory using a deuterated plastic target. The intensity of the 165 keV {gamma}-ray from {sup 76}As in coincidence with ejected protons, from exciting {sup 76}As above the neutron separation energy populating a compound state, was measured. A tight geometry of four segmented germanium clover {gamma}-ray detectors together with eight ORRUBA-type silicon-strip charged-particle detectors was used to optimize geometric acceptance. The preliminary analysis of the {sup 75}As experiment, and the efficacy and future plans of the (d,p{gamma}) surrogate campaign in inverse kinematics, are discussed.

  17. Preparation of thin arsenic and radioarsenic targets for neutron capture studies

    SciTech Connect

    Fassbender, Michael E

    2009-01-01

    A simple method for the electrodeposition of elemental arsenic (As) on a metal backing from aqueous solutions has been developed. The method was successfully applied to stable As (As-75). Thin (2.5 mg {center_dot} cm{sup -2}) coherent, smooth layers of the metalloid on Ti foils (2.5 {micro}m thickness) were obtained. Electrodeposits served as targets for {sup 75}As(n,{gamma}) {sup 76}As neutron capture experiments at Los Alamos Neutron Science Center (LANSCE). Respective {sup 73}As(n,{gamma}) {sup 74}As experiments are planned for the near future, and {sup 73}As targets will be prepared in a similar fashion utilizing the introduced electrodeposition method. The preparation of an {sup 73}As (half-life 80.3 d) plating bath solution from proton irradiated germanium has been demonstrated. Germanium target irradiation was performed at the Los Alamos Isotope Production Facility (IPF).

  18. Neutron Capture Cross Section of Unstable Ni63: Implications for Stellar Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Lederer, C.; Massimi, C.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bcares, V.; Be?v?, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviani, M.; Calvio, F.; Cano-Ott, D.; Carrapio, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Corts, G.; Corts-Giraldo, M. A.; Diakaki, M.; Domingo-Pardo, C.; Duran, I.; Dressler, R.; Dzysiuk, N.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; Garca, A. R.; Giubrone, G.; Gmez-Hornillos, M. B.; Gonalves, I. F.; Gonzlez-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Gurusamy, P.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Kppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Kokkoris, M.; Korschinek, G.; Krti?ka, M.; Kroll, J.; Langer, C.; Leeb, H.; Leong, L. S.; Losito, R.; Manousos, A.; Marganiec, J.; Martnez, T.; Mastinu, P. F.; Mastromarco, M.; Meaze, M.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondelaers, W.; Paradela, C.; Pavlik, A.; Perkowski, J.; Pignatari, M.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego, A.; Roman, F.; Rubbia, C.; Sarmento, R.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J. L.; Tarro, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Wei, C.; Wright, T. J.; ugec, P.

    2013-01-01

    The Ni63(n,?) cross section has been measured for the first time at the neutron time-of-flight facility n_TOF at CERN from thermal neutron energies up to 200 keV. In total, capture kernels of 12 (new) resonances were determined. Maxwellian averaged cross sections were calculated for thermal energies from kT=5-100keV with uncertainties around 20%. Stellar model calculations for a 25M? star show that the new data have a significant effect on the s-process production of Cu63, Ni64, and Zn64 in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

  19. Synthesis and evaluation of boron compounds for neutron capture therapy of malignant brain tumors

    SciTech Connect

    Soloway, A.H.; Barth, R.F.

    1990-01-01

    Boron neutron capture therapy offers the potentiality for treating brain tumors currently resistant to treatment. The success of this form of therapy is directly dependent upon the delivery of sufficient numbers of thermal-neutrons to tumor cells which possess high concentrations of B-10. The objective of this project is to develop chemical methodology to synthesize boron-containing compounds with the potential for becoming incorporated into rapidly-dividing malignant brain tumor cells and excluded from normal components of the brain and surrounding tissues, to develope biological methods for assessing the potential of the compound by use of cell culture or intratumoral injection, to develop analytical methodology for measuring boron in cells and tissue using direct current plasma atomic emission spectroscopy (DCP-AES) and alpha track autoradiography, to develop biochemical and HPLC procedures for evaluating compound uptake and tissue half-life, and to develop procedures required to assess both in vitro and vivo efficacy of BNCT with selected compounds.

  20. Development of an optical fiber type detector using a Eu:LiCaAlF6 scintillator for neutron monitoring in boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Watanabe, Kenichi; Kawabata, Yuya; Yamazaki, Atsushi; Uritani, Akira; Iguchi, Tetsuo; Fukuda, Kentaro; Yanagida, Takayuki

    2015-12-01

    We have developed a small neutron detector probe as a thermal neutron flux monitor for boron neutron capture therapy. The detector consists of an optical fiber and a small Eu:LiCaAlF6 scintillator. In order to improve neutron-gamma ray discrimination capability, we use the small-size scintillator, whose size is controlled to be smaller than fast electron range produced by gamma-rays and larger than the range of charged particles induced by 6Li(n,t) reactions. We confirmed the improved neutron-gamma ray discrimination capability by comparing the detector responses between a small-size scintillator and a slab one. We also evaluated the neutron sensitivity of the fabricated optical fiber type neutron detector to be 210-4 cm2.

  1. Neutron capture cross sections of {sup 184}W and {sup 186}W

    SciTech Connect

    Marganiec, J.; Dillmann, I.; Pardo, C. Domingo; Kaeppeler, F.

    2009-08-15

    The neutron capture cross sections of {sup 184}W and {sup 186}W have been determined by means of the activation technique. The measurements were carried out at the Karlsruhe 3.75-MV Van de Graaff accelerator using the {sup 7}Li(p,n){sup 7}Be reaction for neutron production. Samples of natural composition were irradiated in a quasistellar neutron spectrum for a thermal energy of kT=25 keV. Systematic uncertainties were investigated by variation of the experimental parameters in repeated activations. The induced activities were counted with HPGe detectors via the strongest {gamma}-ray lines in the decay of the respective product nuclei. The measured data were converted into Maxwellian averaged cross sections at kT=30 keV, yielding 221{+-}12 mb and 231{+-}11 mb for {sup 184}W and {sup 186}W, respectively. Together with the result of a previously reported measurement on {sup 180}W, the present values can be used to improve the cross-section trend with neutron number, which is important for extrapolation into the regions of unstable isotopes. These results are of interest for stellar and explosive nucleosynthesis in nuclear astrophysics as well as for technological applications.

  2. LaBr3(Ce) gamma-ray detector for neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Smirnova, M.; Shmanin, E.; Galavanov, A.; Shustov, A.; Ulin, S.; Vlasik, K.; Dmitrenko, V.; Novikov, A.; Orlov, A.; Petrenko, D.; Shmurak, S.; Uteshev, Z.

    2016-02-01

    Results of developing of a gamma-ray detector based on LaBr3(Ce) scintillation crystal for neutron capture therapy are presented. An energy resolution of the detector measured by photomultiplier tube Hamamatsu R6233-100 is showed. It was 2.93% for gamma line 662 keV from a source 137Cs. For radiative capture gamma line of isotope 10B (478 keV) and annihilation line (511 keV) the values were 3.33 and 3.24% respectively. Data analysis of gamma spectra for an estimation of energy resolution threshold required for visual identification gamma lines 478 and 511 keV was made.

  3. A measurement of the thermal neutron capture cross section of /sup 232/Th

    SciTech Connect

    Jones, R.T.; Merritt, J.S.; Okazaki, A.

    1986-06-01

    The thermal neutron capture cross section of /sup 232/Th has been measured relative to that of /sup 197/Au. Foils of gold, thorium metal, and thoria were irradiated together in the NRU reactor thermal column. The /sup 198/Au activity was assayed in a 4..pi gamma.. ionization chamber, which had been previously calibrated with samples of /sup 198/Au standardized by the 4..pi beta..-..gamma.. coincidence method. Protactinium-233 sources were also standardized by this method. Comparison of these sources with the irradiated thorium, by means of a Ge(Li) spectrometer, enabled the /sup 233/Pa activity in the thorium-bearing foils to be determined. Taking the 2200 m/s capture cross section of /sup 197/Au to be 98.8 b, that of /sup 232/Th is found to be 7.33+.0.06b. The uncertainty is at the 95% confidence level and includes an estimate of the systematic uncertainties.

  4. Improved neutron capture data and evaluation with statistical nuclear structure models for transport libraries

    NASA Astrophysics Data System (ADS)

    Sleaford, Bradley William

    My goal in this work was to improve the nuclear data libraries used for transport calculations with respect to the neutron capture reaction. I have taken a new experimental database of discrete gamma spectra from neutron capture and coupled this with a statistical nuclear structure code not used for this purpose before to account for the unresolved gamma ray quasi-continuum associated with medium to heavy target nuclei. This then accounts for all the output gamma channel energy for this reaction thereby conserving total energy as required by the libraries. I then demonstrate that this new evaluation method is shown to reasonably predict the measured spectra. This method allows for improvements in the evaluation process of the discrete gammas and provides self-consistent continuum gamma ray distributions. I then install this new data in libraries and execute transport calculations to benchmark them. I have done this process for some Tungsten, Iron, and Palladium isotopes. I also investigated using a Hauser Feshbach code to model the output spectra from higher energy neutrons and a simple test was done against available experimental inelastic data. The majority of this work involved investigating gamma ray strength functions and level density parameters, and then using these to evaluate the experimental data. In the process I developed a method for tuning these parameters. I have written FORTRAN programs to convert the discrete experimental and modeled quasi-continuum data into the correct format for transport libraries. Future work would require complete modeling of the spectra from higher energy neutrons. In total 26 libraries have been upgraded, benchmarked and are presently in beta testing.

  5. Boron containing magnetic nanoparticles for neutron capture therapy--an innovative approach for specifically targeting tumors.

    PubMed

    Tietze, Rainer; Unterweger, Harald; Drr, Stephan; Lyer, Stefan; Canella, Lea; Kudejova, Petra; Wagner, Franz M; Petry, Winfried; Taccardi, Nicola; Alexiou, Christoph

    2015-12-01

    The selective delivery of (10)B into the tumor tissue remains to be further improved for successful and reliable Boron Neutron Capture Therapy applications. Magnetic Drug Targeting using intraarterially administered superparamagnetic nanoparticles and external magnetic fields already exhibited convincing results in terms of highly efficient and selective drug deposition. Using the same technique for the targeted (10)B delivery is a promising new approach. Here, systematic irradiation experiments of phantom cubes containing different concentrations of boron and nanoparticles as well as varying three-dimensional arrangements have been performed. PMID:26242559

  6. Neutron capture cross sections of {sup 148}Gd and the decay of {sup 149}Gd

    SciTech Connect

    Rios, M. G.; Casperson, R. J.; Krane, K. S.; Norman, E. B.

    2006-10-15

    The thermal cross section and resonance integral were measured for radiative neutron capture by radioactive {sup 148}Gd. The deduced values are {sigma}=9600{+-}900 b and I=28,200{+-}2300. We also deduced upper limits for the n,p and n, {alpha} cross sections, respectively, 0.25 b and 13 b. The {gamma}-ray spectrum from the decay of {sup 149}Gd was studied in singles mode at high resolution to verify the previously determined energies and intensities. From the latter measurements, new transitions are proposed and upper limits are deduced for previously reported transitions.

  7. Potential of boron neutron capture therapy (BNCT) for malignant peripheral nerve sheath tumors (MPNST).

    PubMed

    Fujimoto, Takuya; Andoh, Tooru; Sudo, Tamotsu; Fujita, Ikuo; Fukase, Naomasa; Takeuchi, Tamotsu; Sonobe, Hiroshi; Inoue, Masayoshi; Hirose, Tkanori; Sakuma, Toshiko; Moritake, Hiroshi; Sugimoto, Tohru; Kawamoto, Teruya; Fukumori, Yoshinobu; Yamamoto, Satomi; Atagi, Shinji; Sakurai, Yoshinori; Kurosaka, Masahiro; Ono, Koji; Ichikawa, Hideki; Suzuki, Minoru

    2015-12-01

    Malignant peripheral nerve sheath tumors (MPNST) are relatively rare neoplasms with poor prognosis. At present there is no effective treatment for MPNST other than surgical resection. Nonetheless, the anti-tumor effect of boron neutron capture therapy (BNCT) was recently demonstrated in two patients with MPNST. Subsequently, tumor-bearing nude mice subcutaneously transplanted with a human MPNST cell line were injected with p-borono-L-phenylalanine (L-BPA) and subjected to BNCT. Pathological studies then revealed that the MPNST cells were selectively destroyed by BNCT. PMID:26278348

  8. Tomographic image of prompt gamma ray from boron neutron capture therapy: A Monte Carlo simulation study

    SciTech Connect

    Yoon, Do-Kun; Jung, Joo-Young; Suk Suh, Tae; Jo Hong, Key

    2014-02-24

    Purpose of paper is to confirm the feasibility of acquisition of three dimensional single photon emission computed tomography image from boron neutron capture therapy using Monte Carlo simulation. Prompt gamma ray (478 keV) was used to reconstruct image with ordered subsets expectation maximization method. From analysis of receiver operating characteristic curve, area under curve values of three boron regions were 0.738, 0.623, and 0.817. The differences between length of centers of two boron regions and distance of maximum count points were 0.3 cm, 1.6 cm, and 1.4 cm.

  9. Drug delivery system design and development for boron neutron capture therapy on cancer treatment.

    PubMed

    Sherlock Huang, Lin-Chiang; Hsieh, Wen-Yuan; Chen, Jiun-Yu; Huang, Su-Chin; Chen, Jen-Kun; Hsu, Ming-Hua

    2014-06-01

    We have already synthesized a boron-containing polymeric micellar drug delivery system for boron neutron capture therapy (BNCT). The synthesized diblock copolymer, boron-terminated copolymers (Bpin-PLA-PEOz), consisted of biodegradable poly(D,l-lactide) (PLA) block and water-soluble polyelectrolyte poly(2-ethyl-2-oxazoline) (PEOz) block, and a cap of pinacol boronate ester (Bpin). In this study, we have demonstrated that synthesized Bpin-PLA-PEOz micelle has great potential to be boron drug delivery system with preliminary evaluation of biocompatibility and boron content. PMID:24447933

  10. Leading E1 and M1 contributions to radiative neutron capture on lithium-7

    NASA Astrophysics Data System (ADS)

    Fernando, Lakma; Higa, Renato; Rupak, Gautam

    2012-10-01

    We provide a model-independent calculation of the radiative neutron capture on lithium-7 over an energy range where the contribution from the 3+ resonance becomes important by using halo effective field theory. We describe how the couplings in the EFT Lagrangian are constrained from available data on low-lying bound and resonance states. We also present power counting arguments that establish a hierarchy for electromagnetic one- and two-body currents. Our model independent results quantify the current uncertainties in nuclear theory in the single particle approximation.

  11. Single step synthesis of nanostructured boron nitride for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Singh, Bikramjeet; Singh, Paviter; Kumar, Manjeet; Thakur, Anup; Kumar, Akshay

    2015-05-01

    Nanostructured Boron Nitride (BN) has been successfully synthesized by carbo-thermic reduction of Boric Acid (H3BO3). This method is a relatively low temperature synthesis route and it can be used for large scale production of nanostructured BN. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA). XRD analysis confirmed the formation of single phase nanostructured Boron Nitride. SEM analysis showed that the particles are spherical in shape. DTA analysis showed that the phase is stable upto 900 C and the material can be used for high temperature applications as well boron neutron capture therapy (BNCT).

  12. Thermal neutron capture cross section of gadolinium by pile-oscillation measurements in MINERVE

    SciTech Connect

    Leconte, P.; Di-Salvo, J.; Antony, M.; Pepino, A.; Hentati, A.

    2012-07-01

    Natural gadolinium is used as a burnable poison in most LWR to account for the excess of reactivity of fresh fuels. For an accurate prediction of the cycle length, its nuclear data and especially its neutron capture cross section needs to be known with a high precision. Recent microscopic measurements at Rensselaer Polytechnic Inst. (RPI) suggest a 11% smaller value for the thermal capture cross section of {sup 157}Gd, compared with most of evaluated nuclear data libraries. To solve this inconsistency, we have analyzed several pile-oscillation experiments, performed in the MINERVE reactor. They consist in the measurement of the reactivity variation involved by the introduction in the reactor of small-samples, containing different mass amounts of natural gadolinium. The analysis of these experiments is done through the exact perturbation theory, using the PIMS calculation tool, in order to link the reactivity effect to the thermal capture cross section. The measurement of reactivity effects is used to deduce the 2200 m.s-1 capture cross section of {sup nat}Gd which is (49360 {+-} 790) b. This result is in good agreement with the JEFF3.1.1 value (48630 b), within 1.6% uncertainty at 1{sigma}, but is strongly inconsistent with the microscopic measurements at RPI which give (44200 {+-} 500) b. (authors)

  13. Measurement and resonance analysis of the 237Np neutron capture cross section

    NASA Astrophysics Data System (ADS)

    Guerrero, C.; Cano-Ott, D.; Mendoza, E.; Abbondanno, U.; Aerts, G.; lvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Becvr, F.; Belloni, F.; Berthoumieux, E.; Calvio, F.; Calviani, M.; Capote, R.; Carrapio, C.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Dolfini, R.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Goncalves, I.; Gonzlez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Kppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Ketlerov, V.; Kerveno, M.; Koehler, P.; Konovalov, V.; Kossionides, E.; Krti?ka, M.; Lampoudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lossito, R.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Martnez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vicente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.

    2012-04-01

    The neutron capture cross section of 237Np was measured between 0.7 and 500 eV at the CERN n_TOF facility using the 4? BaF2 Total Absorption Calorimeter. The experimental capture yield was extracted minimizing all the systematic uncertainties and was analyzed together with the most reliable transmission data available using the sammy code. The result is a complete set of individual as well as average resonance parameters [D0=0.56(2) eV, =40.9(18) meV, 104S0=0.98(6), R'=9.8(6) fm]. The capture cross section obtained in this work is in overall agreement with the evaluations and the data of Weston and Todd [Nucl. Sci. Eng. 79, 184 (1981)], thus showing sizable differences with respect to previous data from Scherbakov [J. Nucl. Sci. Technol. 42, 135 (2005)] and large discrepancies with data Kobayashi [J. Nucl. Sci. Technol.JNSTAX0022-313110.3327/jnst.39.111 39, 111 (2002)]. The results indicate that a new evaluation combining the present capture data with reliable transmission data would allow reaching an accuracy better than 4%, in line with the uncertainty requirements of the nuclear data community for the design and operation of current and future nuclear devices.

  14. Boron neutron capture therapy of glioblastoma multiforme using the p- boronophenylalanine-fructose complex and epithermal neutrons

    SciTech Connect

    Coderre, J.A.; Chanana, A.D.; Joel, D.D.; Liu, H.B.; Slatkin, D.N.; Wielopolski, L.; Bergland, R.; Elowitz, E.; Chadha, M.

    1994-12-31

    The amino acid analogue p-boronophenylalanine (BPA) is under investigation as a neutron capture agent for BNCT of glioblastoma multiforme. A series of patients undergoing surgical removal of tumor received BPA orally as the free amino acid. Favorable tumor/blood boron concentration ratios were obtained but the absolute amount of boron in the tumor would have been insufficient for BNCT. BPA can be solubilized at neutral pH by complexation with fructose (BPA-F). Studies with rats suggest that intraperitoneal injection of BPA-F complex produces a much higher tumor boron concentration to rat intracerebral 9L gliosarcoma that were possible with oral BPA. Higher boron concentrations have allowed higher tumor radiation doses to be delivered while maintaining the dose to the normal brain vascular endothelium below the threshold of tolerance. The experience to date of the administration of BPA-F to one patient is provided in this report.

  15. Characterisation of neutron and gamma-ray emission from thick target Be(p,n) reaction for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Guzek, J.; McMurray, W. R.; Mateva, T.; Franklyn, C. B.; Tapper, U. A. S.

    1998-04-01

    Low energy accelerator-based neutron sources have promising potential for use in a clinical treatment of cancer with boron neutron capture therapy (BNCT) and boron neutron capture synovectomy (BNCS). Such sources often utilise a thick target Be(p,n) reaction using incident proton energies from several hundred keV to 1-2 MeV above the reaction threshold of 2.06 MeV. The resulting neutron and gamma-ray beams require considerable moderation and filtration in order to obtain thermal and epithermal neutron fluxes for therapy. The detailed knowledge of neutron and gamma-ray spectra, yield and angular distribution are necessary in order to design effective moderators and filters to be used for the treatment. Thick and thin beryllium target neutron and gamma-ray spectra have been investigated in detail using the time-of-flight (TOF) technique, for incident proton energies from above threshold to 4 MeV. The results show characteristics of neutron and gamma-ray production of importance for the application of this neutron source for BNCT and BNCS.

  16. THE WEAK s-PROCESS IN MASSIVE STARS AND ITS DEPENDENCE ON THE NEUTRON CAPTURE CROSS SECTIONS

    SciTech Connect

    Pignatari, M.; Herwig, F.; Gallino, R.; Bisterzo, S.; Heil, M.; Wiescher, M.; Kaeppeler, F.

    2010-02-20

    The slow neutron capture process in massive stars (weak s process) produces most of the s-process isotopes between iron and strontium. Neutrons are provided by the {sup 22}Ne(alpha,n){sup 25}Mg reaction, which is activated at the end of the convective He-burning core and in the subsequent convective C-burning shell. The s-process-rich material in the supernova ejecta carries the signature of these two phases. In the past years, new measurements of neutron capture cross sections of isotopes beyond iron significantly changed the predicted weak s-process distribution. The reason is that the variation of the Maxwellian-averaged cross sections (MACS) is propagated to heavier isotopes along the s path. In the light of these results, we present updated nucleosynthesis calculations for a 25 M{sub sun} star of Population I (solar metallicity) in convective He-burning core and convective C-burning shell conditions. In comparison with previous simulations based on the Bao et al. compilation, the new measurement of neutron capture cross sections leads to an increase of s-process yields from nickel up to selenium. The variation of the cross section of one isotope along the s-process path is propagated to heavier isotopes, where the propagation efficiency is higher for low cross sections. New {sup 74}Ge, {sup 75}As, and {sup 78}Se MACS result in a higher production of germanium, arsenic, and selenium, thereby reducing the s-process yields of heavier elements by propagation. Results are reported for the He core and for the C shell. In shell C-burning, the s-process nucleosynthesis is more uncertain than in the He core, due to higher MACS uncertainties at higher temperatures. We also analyze the impact of using the new lower solar abundances for CNO isotopes on the s-process predictions, where CNO is the source of {sup 22}Ne, and we show that beyond Zn this is affecting the s-process yields more than nuclear or stellar model uncertainties considered in this paper. In particular, using the new updated initial composition, we obtain a high s-process production (overproduction higher than {sup 16}O, {approx}100) for Cu, Ga, Ge, and As. Using the older abundances by Anders and Grevesse, also Se, Br, Kr, and Rb are efficiently produced. Our results have important implications in explaining the origin of copper in the solar abundance distribution, pointing to a prevailing contribution from the weak s-process in agreement with spectroscopic observations and Galactic chemical evolution calculations. Because of the improvement due to the new MACS for nickel and copper isotopes, the nucleosynthesis of copper is less affected by nuclear uncertainties compared to heavier s-process elements. An experimental determination of the {sup 63}Ni MACS is required for a further improvement of the abundance prediction of copper. The available spectroscopic observations of germanium and gallium in stars are also discussed, where most of the cosmic abundances of these elements derives from the s-process in massive stars.

  17. OCEAN: An ambitious experimental program for the qualification of integral capture cross sections of neutron absorbers

    SciTech Connect

    Hudelot, J. P.; Antony, M.; Bernard, D.; Leconte, P.; Testaniere, S.; Fougeras, P.

    2006-07-01

    OCEAN (Oscillation in Core of Samples of Neutron Absorbers) is an ambitious experimental program supported by EDF and CEA. It is carried out in the MINERVE reactor of CEA Cadarache which is a low-power uranium fueled pool reactor. It started in 2005 and will end in 2008. It aims at improving the knowledge on nuclear basic data for the neutron absorbers. It deals at the same time with the improvement of the calculation tools and with the feasibility studies on the new options of the fuel cycle. It particularly supports, for the LWR reactors, the studies on the increase of the fuel cycle length in nuclear power plants, and on the plutonium management. It also aims at qualifying the calculation tools as regard with new neutron absorbers. The main framework is the European JEFF3 project. More in details, it deals with providing precise experimental data (capture cross sections) about the following absorbers: Gd-155, Gd-157, Gd-Nat, Hf-177, Hf-178, Hf-179, Hf-180, Er-166, Er-167, Er-168, Er-170, Dy-160, Dy-161, Dy-162, Dy-163, Dy-164, Eu-151, Eu-nat, and Eu-153. The study of the neutron absorbers is performed on a large range of neutron spectra (over-moderated thermal spectrum, PWR UOx standard spectrum, PWR 100% MOX spectrum and epithermal HCLWR type spectrum) corresponding respectively to the R2-UO{sub 2}, R1-UO{sub 2}, R1-MOX and MORGANE-R experimental lattices inside the MINERVE reactor. This paper first presents the objectives of the OCEAN experimental program. Then the description of the MINERVE facility is given, focusing on the different core configurations that will be studied, and the oscillation technique is reminded. Besides, the oscillation samples specially fabricated for the OCEAN program are described. Finally, the first preliminary experimental results in the R1-UO{sub 2} lattice are given and commented. (authors)

  18. Detector-Response Correction of Two-Dimensional γ -Ray Spectra from Neutron Capture

    DOE PAGESBeta

    Rusev, G.; Jandel, M.; Arnold, C. W.; Bredeweg, T. A.; Couture, A.; Mosby, S. M.; Ullmann, J. L.

    2015-05-28

    The neutron-capture reaction produces a large variety of γ-ray cascades with different γ-ray multiplicities. A measured spectral distribution of these cascades for each γ-ray multiplicity is of importance to applications and studies of γ-ray statistical properties. The DANCE array, a 4π ball of 160 BaF2 detectors, is an ideal tool for measurement of neutron-capture γ-rays. The high granularity of DANCE enables measurements of high-multiplicity γ-ray cascades. The measured two-dimensional spectra (γ-ray energy, γ-ray multiplicity) have to be corrected for the DANCE detector response in order to compare them with predictions of the statistical model or use them in applications. Themore » detector-response correction problem becomes more difficult for a 4π detection system than for a single detector. A trial and error approach and an iterative decomposition of γ-ray multiplets, have been successfully applied to the detector-response correction. Applications of the decomposition methods are discussed for two-dimensional γ-ray spectra measured at DANCE from γ-ray sources and from the 10B(n, γ) and 113Cd(n, γ) reactions.« less

  19. Homogeneous immunoconjugates for boron neutron-capture therapy: Design, synthesis, and preliminary characterization

    PubMed Central

    Guan, Lufeng; Wims, Letitia A.; Kane, Robert R.; Smuckler, Mark B.; Morrison, Sherie L.; Hawthorne, M. Frederick

    1998-01-01

    The application of immunoprotein-based targeting strategies to the boron neutron-capture therapy of cancer poses an exceptional challenge, because viable boron neutron-capture therapy by this method will require the efficient delivery of 103 boron-10 atoms by each antigen-binding protein. Our recent investigations in this area have been focused on the development of efficient methods for the assembly of homogeneous immunoprotein conjugates containing the requisite boron load. In this regard, engineered immunoproteins fitted with unique, exposed cysteine residues provide attractive vehicles for site-specific modification. Additionally, homogeneous oligomeric boron-rich phosphodiesters (oligophosphates) have been identified as promising conjugation reagents. The coupling of two such boron-rich oligophosphates to sulfhydryls introduced to the CH2 domain of a chimeric IgG3 has been demonstrated. The resulting boron-rich immunoconjugates are formed efficiently, are readily purified, and have promising in vitro and in vivo characteristics. Encouragingly, these studies showed subtle differences in the properties of the conjugates derived from the two oligophosphate molecules studied, providing a basis for the application of rational design to future work. Such subtle details would not have been as readily discernible in heterogeneous conjugates, thus validating the rigorous experimental design employed here. PMID:9789066

  20. Homogeneous immunoconjugates for boron neutron-capture therapy: design, synthesis, and preliminary characterization.

    PubMed

    Guan, L; Wims, L A; Kane, R R; Smuckler, M B; Morrison, S L; Hawthorne, M F

    1998-10-27

    The application of immunoprotein-based targeting strategies to the boron neutron-capture therapy of cancer poses an exceptional challenge, because viable boron neutron-capture therapy by this method will require the efficient delivery of 10(3) boron-10 atoms by each antigen-binding protein. Our recent investigations in this area have been focused on the development of efficient methods for the assembly of homogeneous immunoprotein conjugates containing the requisite boron load. In this regard, engineered immunoproteins fitted with unique, exposed cysteine residues provide attractive vehicles for site-specific modification. Additionally, homogeneous oligomeric boron-rich phosphodiesters (oligophosphates) have been identified as promising conjugation reagents. The coupling of two such boron-rich oligophosphates to sulfhydryls introduced to the CH2 domain of a chimeric IgG3 has been demonstrated. The resulting boron-rich immunoconjugates are formed efficiently, are readily purified, and have promising in vitro and in vivo characteristics. Encouragingly, these studies showed subtle differences in the properties of the conjugates derived from the two oligophosphate molecules studied, providing a basis for the application of rational design to future work. Such subtle details would not have been as readily discernible in heterogeneous conjugates, thus validating the rigorous experimental design employed here. PMID:9789066

  1. Detector-Response Correction of Two-Dimensional ?-Ray Spectra from Neutron Capture

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Jandel, M.; Arnold, C. W.; Bredeweg, T. A.; Couture, A.; Mosby, S. M.; Ullmann, J. L.

    2015-05-01

    The neutron-capture reaction produces a large variety of ?-ray cascades with different ?-ray multiplicities. A measured spectral distribution of these cascades for each ?-ray multiplicity is of importance to applications and studies of ?-ray statistical properties. The DANCE array, a 4? ball of 160 BaF2 detectors, is an ideal tool for measurement of neutron-capture ?-rays. The high granularity of DANCE enables measurements of high-multiplicity ?-ray cascades. The measured two-dimensional spectra (?-ray energy, ?-ray multiplicity) have to be corrected for the DANCE detector response in order to compare them with predictions of the statistical model or use them in applications. The detector-response correction problem becomes more difficult for a 4? detection system than for a single detector. A trial and error approach and an iterative decomposition of ?-ray multiplets, have been successfully applied to the detector-response correction. Applications of the decomposition methods are discussed for two-dimensional ?-ray spectra measured at DANCE from ?-ray sources and from the 10B(n, ?) and 113Cd(n, ?) reactions.

  2. Hemorrhage in mouse tumors induced by dodecaborate cluster lipids intended for boron neutron capture therapy.

    PubMed

    Schaffran, Tanja; Jiang, Nan; Bergmann, Markus; Kstermann, Ekkehard; Sss, Regine; Schubert, Rolf; Wagner, Franz M; Awad, Doaa; Gabel, Detlef

    2014-01-01

    The potential of boron-containing lipids with three different structures, which were intended for use in boron neutron capture therapy, was investigated. All three types of boron lipids contained the anionic dodecaborate cluster as the headgroup. Their effects on two different tumor models in mice following intravenous injection were tested; for this, liposomes with boron lipid, distearoyl phosphatidylcholine, and cholesterol as helper lipids, and containing a polyethylene glycol lipid for steric protection, were administered intravenously into tumor-bearing mice (C3H mice for SCCVII squamous cell carcinoma and BALB/c mice for CT26/WT colon carcinoma). With the exception of one lipid (B-THF-14), the lipids were well tolerated, and no other animal was lost due to systemic toxicity. The lipid which led to death was not found to be much more toxic in cell culture than the other boron lipids. All of the lipids that were well tolerated showed hemorrhage in both tumor models within a few hours after administration. The hemorrhage could be seen by in vivo magnetic resonance and histology, and was found to occur within a few hours. The degree of hemorrhage depended on the amount of boron administered and on the tumor model. The observed unwanted effect of the lipids precludes their use in boron neutron capture therapy. PMID:25114527

  3. Neutron Capture Elements in the Open Cluster Chemical Abundance & Mapping (OCCAM) Survey

    NASA Astrophysics Data System (ADS)

    O'Connell, Julia; Frinchaboy, Peter M.; Shetrone, Matthew D.; Majewski, Steven R.; Zasowski, Gail; Hearty, Fred R.

    2016-01-01

    The Open Cluster Chemical Abundance & Mapping (OCCAM) survey is a systematic survey of Galactic open clusters using data primarily from the SDSS-III/APOGEE-1 survey. The high-resolution (R=22,500), near-infrared (H-band) APOGEE-1 survey allows for cluster membership probability determination and analysis of light and iron-peak elements. Neutron capture elements, however, prove to be elusive in the IR region covered by APOGEE. In an effort to fully study detailed Galactic chemical evolution, we conducted a high resolution (R~60,000) spectroscopic abundance analysis of neutron capture elements for OCCAM clusters in the optical regime to complement the APOGEE results. We present results for ten open clusters using data obtained at McDonald Observatory with the 2.1m Otto Struve telescope and Sandiford Echelle Spectrograph. We see abundance trends for Ba II, La II and Eu II that are consistent with Galactic abundance patterns for these elements. Ce II appears to be slightly enhanced in all program stars with a median value of ~0.1 dex and a spread of 0.5 dex for the entire sample.

  4. Hemorrhage in mouse tumors induced by dodecaborate cluster lipids intended for boron neutron capture therapy

    PubMed Central

    Schaffran, Tanja; Jiang, Nan; Bergmann, Markus; Kstermann, Ekkehard; Sss, Regine; Schubert, Rolf; Wagner, Franz M; Awad, Doaa; Gabel, Detlef

    2014-01-01

    The potential of boron-containing lipids with three different structures, which were intended for use in boron neutron capture therapy, was investigated. All three types of boron lipids contained the anionic dodecaborate cluster as the headgroup. Their effects on two different tumor models in mice following intravenous injection were tested; for this, liposomes with boron lipid, distearoyl phosphatidylcholine, and cholesterol as helper lipids, and containing a polyethylene glycol lipid for steric protection, were administered intravenously into tumor-bearing mice (C3H mice for SCCVII squamous cell carcinoma and BALB/c mice for CT26/WT colon carcinoma). With the exception of one lipid (B-THF-14), the lipids were well tolerated, and no other animal was lost due to systemic toxicity. The lipid which led to death was not found to be much more toxic in cell culture than the other boron lipids. All of the lipids that were well tolerated showed hemorrhage in both tumor models within a few hours after administration. The hemorrhage could be seen by in vivo magnetic resonance and histology, and was found to occur within a few hours. The degree of hemorrhage depended on the amount of boron administered and on the tumor model. The observed unwanted effect of the lipids precludes their use in boron neutron capture therapy. PMID:25114527

  5. Improved methods for the generation of 24.5 keV neutron beams with possible application to boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Constantine, G.; Baker, L. J.; Taylor, N. P.

    1986-09-01

    The production of epithermal neutron beams, filtered to provide a spectrum in which a small energy range predominates, is of importance for radiobiological research and in the development and calibration of instruments for monitoring intermediate energy neutrons. The penetration characteristics of intermediate energy neutrons in tissue lead to the possibility of application in the field of neutron capture therapy if beams of sufficient intensity and adequate spectral properties can be generated. In this paper methods of utilising the 24.5 keV antiresonance in the iron neutron cross section are described, and the DENIS (depth enhanced neutron intense source) principle by which beam intensities may be optimised is explained. Calculations and experimental measurements in an in-core facility in the DIDO reactor at Harwell have indicated that a DENIS scatterer can achieve a 6-fold improvement in 24.5 keV beam intensity compared with a conventional titanium disc scatterer.

  6. Boron neutron capture therapy (BNCT) for liver metastasis: therapeutic efficacy in an experimental model

    SciTech Connect

    David W. Nigg

    2012-08-01

    Boron neutron capture therapy (BNCT) was proposed for untreatable colorectal liver metastases. The present study evaluates tumor control and potential radiotoxicity of BNCT in an experimental model of liver metastasis. BDIX rats were inoculated with syngeneic colon cancer cells DHD/K12/TRb. Tumor-bearing animals were divided into three groups: BPA–BNCT, boronophenylalanine (BPA) ? neutron irradiation; Beam only, neutron irradiation; Sham, matched manipulation. The total absorbed dose administered with BPA–BNCT was 13 ± 3 Gy in tumor and 9 ± 2 Gy in healthy liver. Three weeks posttreatment, the tumor surface area post-treatment/pre-treatment ratio was 0.46 ± 0.20 for BPA–BNCT, 2.7 ± 1.8 for Beam only and 4.5 ± 3.1 for Sham. The pre-treatment tumor nodule mass of 48 ± 19 mgfell significantly to 19 ± 16 mg for BPA–BNCT, but rose significantly to 140 ± 106 mg for Beam only and to 346 ± 302 mg for Sham. For both end points, the differences between the BPA–BNCT group and each of the other groups were statistically significant (ANOVA). No clinical, macroscopic or histological normal liver radiotoxicity was observed. It is concluded that BPA– BNCT induced a significant remission of experimental colorectal tumor nodules in liver with no contributory liver toxicity.

  7. Stellar neutron capture cross sections of Nd, Pm, and Sm isotopes

    SciTech Connect

    Toukan, K.A. ); Debus, K.; Kaeppeler, F. ); Reffo, G. )

    1995-03-01

    The neutron capture cross sections of [sup 146,148,150]Nd have been determined relative to that of gold by means of the activation method. The samples were irradiated in a quasistellar neutron spectrum for [ital kT]=25 keV using the [sup 7]Li([ital p],[ital n])[sup 7]Be reaction near threshold. Variation of the experimental conditions in different activations and the use of different samples allowed for the reliable determination of corrections and the evaluation of systematic uncertainties. The resulting stellar cross sections can be given with uncertainties around 6%, which represents a considerable improvement compared to previous measurements. These data are complemented by a new set of calculated cross sections for the unstable isotopes [sup 147]Nd, [sup 147,148,149]Pm, and [sup 151]Sm, which act as branching points in the [ital s]-process path. Based on these results, the [ital s]-process flow in the Nd-Pm-Sm region is discussed with respect to the neutron density during stellar helium burning and to isotopic anomalies in meteorites. The updated [ital s]-abundances are also used for a discussion of [ital r]- and [ital p]-process residuals.

  8. Monte Carlo simulation of depth dose distribution in several organic models for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.

    2007-09-01

    Monte Carlo simulations are performed to evaluate depth-dose distributions for possible treatment of cancers by boron neutron capture therapy (BNCT). The ICRU computational model of ADAM & EVA was used as a phantom to simulate tumors at a depth of 5 cm in central regions of the lungs, liver and pancreas. Tumors of the prostate and osteosarcoma were also centered at the depth of 4.5 and 2.5 cm in the phantom models. The epithermal neutron beam from a research reactor was the primary neutron source for the MCNP calculation of the depth-dose distributions in those cancer models. For brain tumor irradiations, the whole-body dose was also evaluated. The MCNP simulations suggested that a lethal dose of 50 Gy to the tumors can be achieved without reaching the tolerance dose of 25 Gy to normal tissue. The whole-body phantom calculations also showed that the BNCT could be applied for brain tumors without significant damage to whole-body organs.

  9. Recoil Induced Room Temperature Stable Frenkel Pairs in a-Hafnium Upon Thermal Neutron Capture

    NASA Astrophysics Data System (ADS)

    Butz, Tilman; Das, Satyendra K.; Dey, Chandi C.; Ghoshal, Shamik

    2013-11-01

    Ultrapure hafnium metal (110 ppm zirconium) was neutron activated with a thermal neutron flux of 6:6 1012 cm-2s-1 in order to obtain 181Hf for subsequent time differential perturbed angular correlation (TDPAC) experiments using the nuclear probe 181Hf(?-) 181Ta. Apart from the expected nuclear quadrupole interaction (NQI) signal for a hexagonal close-packed (hcp) metal, three further discrete NQIs were observed with a few percent fraction each. The TDPAC spectra were recorded for up to 11 half lives with extreme statistical accuracy. The fitted parameters vary slightly within the temperature range between 248 K and 373 K. The signals corresponding to the three additional sites completely disappear after `annealing' at 453 K for one minute. Based on the symmetry of the additional NQIs and their temperature dependencies, they are tentatively attributed to Frenkel pairs produced by recoil due to the emission of a prompt 5:694 MeV -ray following thermal neutron capture and reported by the nuclear probe in three different positions. These Frenkel pairs are stable up to at least 373 K.

  10. Irradiation facility for boron neutron capture therapy application based on a rf-driven D-T neutron source and a new beam shaping assembly (abstract)

    NASA Astrophysics Data System (ADS)

    Cerullo, N.; Esposito, J.; Leung, K. N.

    2002-02-01

    Selecting the best neutron source for boron neutron capture therapy (BNCT) requires optimizing neutron beam parameters. This involves solving many complex problems. Safety issues related to the use of nuclear reactor in hospital environments, as well as lower costs have led to interest in the development of accelerator-driven neutron sources. The BNCT research programs at the Nuclear Departments of Pisa and Genova Universities (DIMNP and DITEC) focus on studies of new concepts for accelerator-based DT neutron sources. Simple and compact accelerator designs using relatively low deuteron beam energy, 100 keV, have been developed which, in turn, can generate high neutron yields. New studies have been started for optimization of moderator materials for the 14.1 MeV DT neutrons. Our aim is to obtain an epithermal neutron beam for therapeutic application at the exit end, with minimal beam intensity losses, the specific goal is to achieve an epithermal neutron flux of at least of 1109 n/cm2 s at the beam port, with low gamma and fast neutron dose contamination. According to the most recent neutron BNCT beam parameters some moderating and spectrum shifter materials and geometrical configurations have thus far been tested, and neutron and gamma beam data at beam port have been computed. A possible beam shaping assembly model has been designed. This research demonstrates that a DT neutron source could be successfully implemented for BNCT application, with performance surpassing the minimum requirements stated above, using DT neutron sources with yields in the range 1013-1014 n/s. The latest Monte Carlo simulation results of an accelerator based facility which relies on a rf-driven DT fusion neutron generator will be presented.

  11. Transmission of very slow neutrons through material foils and its influence on the design of ultracold neutron sources

    NASA Astrophysics Data System (ADS)

    Atchison, F.; Blau, B.; Bollhalder, A.; Daum, M.; Fierlinger, P.; Geltenbort, P.; Hampel, G.; Kasprzak, M.; Kirch, K.; Kchli, S.; Kuczewski, B.; Leber, H.; Locher, M.; Meier, M.; Ochse, S.; Pichlmaier, A.; Plonka, C.; Reiser, R.; Ulrich, J.; Wang, X.; Wiehl, N.; Zimmer, O.; Zsigmond, G.

    2009-09-01

    At the Paul Scherrer Institute (PSI), a very intense source of ultracold neutrons (UCN) is being built. The UCN converter of solid deuterium must be contained in a vessel. Produced UCN leave that vessel through its top lid. To decide on the design of the vessel and the top lid, we have measured the transmission of neutrons with velocities between 3 and 20 m/s through different material foils. Contrary to expectations, we found that transmission through aluminium and aluminium alloys is equal or even higher compared to zirconium and reactor-grade zirconium alloys, respectively.

  12. A coupled deterministic/stochastic method for computing neutron capture therapy dose rates

    NASA Astrophysics Data System (ADS)

    Hubbard, Thomas Richard

    Neutron capture therapy (NCT) is an experimental method of treating brain tumors and other cancers by: (1) injecting or infusing the patient with a tumor-seeking, neutron target-labeled drug; and (2) irradiating the patient in an intense epithermal neutron fluence. The nuclear reaction between the neutrons and the target nuclei (e.g. sp{10}B(n,alpha)sp7Lirbrack releases energy in the form of high-LET (i.e. energy deposited within the range of a cell diameter) reaction particles which selectively kill the tumor cell. The efficacy of NCT is partly dependent on the delivery of maximum thermal neutron fluence to the tumor and the minimization of radiation dose to healthy tissue. Since the filtered neutron source (e.g. research reactor) usually provides a broad energy spectrum of highly-penetrating neutron and gamma-photon radiation, detailed transport calculations are necessary in order to plan treatments that use optimal treatment facility configurations and patient positioning. Current computational methods for NCT use either discrete ordinates calculation or, more often, Monte Carlo simulation to predict neutron fluences in the vicinity of the tumor. These methods do not, however, accurately calculate the transport of radiation throughout the entire facility or the deposition of dose in all the various parts of the body due to shortcomings of using either method alone. A computational method, specifically designed for NCT problems, has been adapted from the MASH methodology and couples a forward discrete ordinates (Ssb{n}) calculation with an adjoint Monte Carlo run to predict the dose at any point within the patient. The transport from the source through the filter/collimator is performed with a forward DORT run, and this is then coupled to adjoint MORSE results at a selected coupling parallelepiped which surrounds human phantom. Another routine was written to allow the user to generate the MORSE models at various angles and positions within the treatment room. The new method was validated by comparing results to experimental measurements and benchmark data in a series of test cases chosen to demonstrate the strengths and weaknesses of the method. Experimental cases included the SAINT gold foil irradiations at the UVAR and detailed phantom dosimetry measurements at the Brookhaven Medical Research Reactor (BMRR). Results of the validation studies showed that the method provides values that are, in most cases, within one fractional standard deviation (FSD) of accepted experimental and benchmark values. A sample brain tumor treatment case was modeled for the conceptual UVAR NCT facility in order to determine the effect of body orientation, size, position, and shielding on the neutron dose rate at a variety of body parts. Ssb{n} "ray effects" were apparent and caused inaccuracies toward the back of the coupling surface; these can be avoided. The method provides treatment planners the ability to calculate dose rates throughout a patient's body and in the treatment room for various treatment configurations in order to minimize the dose to healthy tissue. The thermal neutrons provide the major contribution to neutron dose, but their effect can be minimized by applying localized shielding and by orienting the patient in order to maximize self-shielding. The method may also be used for facility design studies, and such studies of the UVAR have confirmed its suitability as an NCT facility.

  13. Pulse-width analysis for neutron capture cross-section measurement using an NaI(Tl) detector

    NASA Astrophysics Data System (ADS)

    Katabuchi, Tatsuya; Matsuhashi, Taihei; Terada, Kazushi; Arai, Takuro; Furutaka, Kazuyoshi; Hara, Kaoru Y.; Harada, Hideo; Hirose, Kentaro; Hori, Jun-ichi; Igashira, Masayuki; Kamiyama, Takashi; Kimura, Atsushi; Kino, Koichi; Kitatani, Fumito; Kiyanagi, Yoshiaki; Koizumi, Mitsuo; Mizumoto, Motoharu; Nakamura, Shoji; Oshima, Masumi; Toh, Yosuke

    2014-11-01

    A fast data acquisition method based on pulse-width analysis was developed for measuring neutron capture cross-sections using an NaI(Tl) detector. The new method was tested by detecting ?-rays from standard ?-ray sources and neutron-induced reactions. Non-linear relation between the ?-ray energy and the pulse width of the detector output signal was studied. The neutron beam experiments were performed using a pulsed neutron beam from a spallation neutron source at the Japan Proton Accelerator Research Complex. Detector-deposited energy spectra were reconstructed from the pulse-width spectra using the parameterized relation between the pulse width and the ?-ray energy. Time response properties of the pulse-width analysis method were compared with the traditional pulse-height analysis method. Detailed analysis of the experimental results demonstrated that the present method was more resistive to intense ?-ray bursts from the spallation neutron source.

  14. The impact of updated Zr neutron-capture cross sections and new asymptotic giant branch models on our understanding of the S process and the origin of stardust

    SciTech Connect

    Lugaro, Maria; Tagliente, Giuseppe; Karakas, Amanda I.; Milazzo, Paolo M.; Käppeler, Franz; Davis, Andrew M.; Savina, Michael R. E-mail: giuseppe.tagliente@ba.infn.it E-mail: paolo.milazzo@ts.infn.it E-mail: a-davis@uchicago.edu

    2014-01-01

    We present model predictions for the Zr isotopic ratios produced by slow neutron captures in C-rich asymptotic giant branch (AGB) stars of masses 1.25-4 M {sub ☉} and metallicities Z = 0.01-0.03, and compare them to data from single meteoritic stardust silicon carbide (SiC) and high-density graphite grains that condensed in the outflows of these stars. We compare predictions produced using the Zr neutron-capture cross sections from Bao et al. and from n{sub T}OF experiments at CERN, and present a new evaluation for the neutron-capture cross section of the unstable isotope {sup 95}Zr, the branching point leading to the production of {sup 96}Zr. The new cross sections generally present an improved match with the observational data, except for the {sup 92}Zr/{sup 94}Zr ratios, which are on average still substantially higher than predicted. The {sup 96}Zr/{sup 94}Zr ratios can be explained using our range of initial stellar masses, with the most {sup 96}Zr-depleted grains originating from AGB stars of masses 1.8-3 M {sub ☉} and the others from either lower or higher masses. The {sup 90,} {sup 91}Zr/{sup 94}Zr variations measured in the grains are well reproduced by the range of stellar metallicities considered here, which is the same needed to cover the Si composition of the grains produced by the chemical evolution of the Galaxy. The {sup 92}Zr/{sup 94}Zr versus {sup 29}Si/{sup 28}Si positive correlation observed in the available data suggests that stellar metallicity rather than rotation plays the major role in covering the {sup 90,} {sup 91,} {sup 92}Zr/{sup 94}Zr spread.

  15. Exploring Boron Neutron Capture Therapy for non-small cell lung cancer.

    PubMed

    Faras, Rubn O; Bortolussi, Silva; Menndez, Pablo R; Gonzlez, Sara J

    2014-12-01

    Boron Neutron Capture Therapy (BNCT) is a radiotherapy that combines biological targeting and high LET radiation. It consists in the enrichment of tumour with (10)B and in the successive irradiation of the target with low energy neutrons producing charged particles that mainly cause non-repairable damages to the cells. The feasibility to treat Non Small Cells Lung Cancer (NSCLC) with BNCT was explored. This paper proposes a new approach to determine treatment plans, introducing the possibility to choose the irradiation start and duration to maximize the tumour dose. A Tumour Control Probability (TCP) suited for lung BNCT as well as other high dose radiotherapy schemes was also introduced. Treatment plans were evaluated in localized and disseminated lung tumours. Semi-ideal and real energy spectra beams were employed to assess the best energy range and the performance of non-tailored neutron sources for lung tumour treatments. The optimal neutron energy is within [500eV-3keV], lower than the 10keV suggested for the treatment of deep-seated tumours in the brain. TCPs higher than 0.6 and up to 0.95 are obtained for all cases. Conclusions drawn from [Suzuki etal., Int Canc Conf J 1 (4) (2012) 235-238] supporting the feasibility of BNCT for shallow lung tumours are confirmed, however discussions favouring the treatment of deeper lesions and disseminated disease are also opened. Since BNCT gives the possibility to deliver a safe and potentially effective treatment for NSCLC, it can be considered a suitable alternative for patients with few or no treatment options. PMID:25176019

  16. Boron neutron capture therapy for glioblastoma multiforme: clinical studies in Sweden.

    PubMed

    Capala, Jacek; Stenstam, Britta H; Skld, Kurt; Munck af Rosenschld, Per; Giusti, Valerio; Persson, Charlotta; Wallin, Eva; Brun, Arne; Franzen, Lars; Carlsson, Jrgen; Salford, Leif; Ceberg, Crister; Persson, Bertil; Pellettieri, Luigi; Henriksson, Roger

    2003-01-01

    A boron neutron capture therapy (BNCT) facility has been constructed at Studsvik, Sweden. It includes two filter/moderator configurations. One of the resulting neutron beams has been optimized for clinical irradiations with a filter/moderator system that allows easy variation of the neutron spectrum from the thermal to the epithermal energy range. The other beam has been designed to produce a large uniform field of thermal neutrons for radiobiological research. Scientific operations of the Studsvik BNCT project are overseen by the Scientific Advisory Board comprised of representatives of major universities in Sweden. Furthermore, special task groups for clinical and preclinical studies have been formed to facilitate collaboration with academia. The clinical Phase II trials for glioblastoma are sponsored by the Swedish National Neuro-Oncology Group and, presently, involve a protocol for BNCT treatment of glioblastoma patients who have not received any therapy other than surgery. In this protocol, p-boronophenylalanine (BPA), administered as a 6-h intravenous infusion, is used as the boron delivery agent. As of January 2002, 17 patients were treated. The 6-h infusion of 900 mg BPA/kg body weight was shown to be safe and resulted in the average blood-boron concentration of 24 microg/g (range: 15-32 microg/g) at the time of irradiation (approximately 2-3 h post-infusion). Peak and average weighted radiation doses to the brain were in the ranges of 8.0-15.5 Gy(W) and 3.3-6.1 Gy(W), respectively. So far, no severe BNCT-related acute toxicities have been observed. Due to the short follow-up time, it is too early to evaluate the efficacy of these studies. PMID:12749709

  17. Radiobiology of boron neutron capture therapy: Problems with the concept of relative biological effectiveness

    SciTech Connect

    Coderre, J.A.; Makar, M.S.

    1990-01-01

    The radiation dose delivered to cells in vitro or vivo during boron neutron capture therapy (BNCT) is a mixture of photons, fast neutrons and heavy charged particles from the interaction of neutrons with nitrogen and born. The concept of relative biological effectiveness (RBE) had been developed to allow comparison of the effects of these radiations with the effects of standard photon treatments such as 250 kVp x-rays or {sup 60}Co gamma rays. The RBE value for all of these high linear energy transfer radiations can vary considerably depending upon the experimental conditions and endpoint utilized. The short range of the particles from the {sup 10}B(n,{alpha}) {sup 7}Li reaction make the precise subcellular location of the {sup 10}B atom of critical importance. The microscopic distribution of the {sup 10}B has a decided effect on the dosimetry. Monte Carlo simulations have shown that, at the cellular level, there is a profound difference in the probability of cell kill depending on the location of the {sup 10}B relative to the nucleus. Different boron-delivery agents will almost certainly have different distribution patterns at the subcellular level. The effect of BNCT with the amino acid p-boronophenylalanine (BPA) was compared with the effect of 250 kVp x-rays on a pigmented B16 melanoma subclone, both in vitro and in vivo. Generally accepted RBE values were applied to the relevant components of the Brookhaven Medical Research Reactor (BMRR) thermal neutron beam, however, there were still discrepancies when the resulting dose response curves were compared with the response to 250 kVp x-rays.

  18. Noble gas excimer scintillation following neutron capture in boron thin films

    SciTech Connect

    McComb, Jacob C.; Al-Sheikhly, Mohamad; Coplan, Michael A.; Thompson, Alan K.; Vest, Robert E.; Clark, Charles W.

    2014-04-14

    Far-ultraviolet scintillation signals have been measured in heavy noble gases (argon, krypton, xenon) following boron-neutron capture ({sup 10}B(n,α){sup 7}Li) in {sup 10}B thin films. The observed scintillation yields are comparable to the yields from some liquid and solid neutron scintillators. At noble gas pressures of 107 kPa, the number of photons produced per neutron absorbed following irradiation of a 1200 nm thick {sup 10}B film was 14 000 for xenon, 11 000 for krypton, and 6000 for argon. The absolute scintillation yields from the experimental configuration were calculated using data from (1) experimental irradiations, (2) thin-film characterizations, (3) photomultiplier tube calibrations, and (4) photon collection modeling. Both the boron films and the photomultiplier tube were characterized at the National Institute of Standards and Technology. Monte Carlo modeling of the reaction cell provided estimates of the photon collection efficiency and the transport behavior of {sup 10}B(n,α){sup 7}Li reaction products escaping the thin films. Scintillation yields increased with gas pressure due to increased ionization and excitation densities of the gases from the {sup 10}B(n,α){sup 7}Li reaction products, increased frequency of three-body, excimer-forming collisions, and reduced photon emission volumes (i.e., larger solid angle) at higher pressures. Yields decreased for thicker {sup 10}B thin films due to higher average energy loss of the {sup 10}B(n,α){sup 7}Li reaction products escaping the films. The relative standard uncertainties in the measurements were determined to lie between 14% and 16%. The observed scintillation signal demonstrates that noble gas excimer scintillation is promising for use in practical neutron detectors.

  19. Role of the bound-state wave function in capture-loss rates: Slow proton in an electron gas

    SciTech Connect

    Alducin, M.; Nagy, I.

    2003-07-01

    Capture and loss rates for protons moving in an electron gas are calculated using many-body perturbation theory. The role of the form of the bound-state wave function for weakly bound states around the proton is analyzed. We find significant differences (up to a factor of 2 higher) in the values of Auger capture and loss rates when using Hulthen-type instead of hydrogenic wave functions. Its relevance in stopping power is briefly discussed.

  20. 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 1.910(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

  1. Mixed-field dosimetry measurement of a target assembly for an accelerator-based neutron source for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Reed, M. K.; Dobelbower, M. C.; Woollard, J. E.; Blue, T. E.

    1998-12-01

    The objective of this work was to measure the neutron and gamma-ray absorbed dose components for a target assembly for an Accelerator-Based Neutron Source (ABNS) for Boron Neutron Capture Therapy (BNCT), and to compare these measurements with MCNP calculations in order to verify the calculations of the in-air neutron and gamma-ray absorbed dose components. The measurements were made using the paired ionization chamber technique. The measured neutron and gamma-ray specific absorbed dose components agreed with calculations within experimental errors, which were approximately 10%. The measured gamma-ray specific absorbed dose rate of 140 cGy s -1 A -1 12% is consistent with reported yields of 478 keV gamma rays due to the 7Li(p, p') 7Li * reaction. This specific gamma absorbed dose rate is significant and should not be neglected in moderator assembly design.

  2. Radiative-neutron-capture gamma-ray analysis by a linear combination technique

    USGS Publications Warehouse

    Tanner, A.B.; Bhargava, R.C.; Senftle, F.E.; Brinkerhoff, J.M.

    1972-01-01

    The linear combination technique, when applied to a gamma-ray spectrum, gives a single number indicative of the extent to which the spectral lines of a sought element are present in a complex spectrum. Spectra are taken of the sought element and of various other substances whose spectra interfere with that of the sought element. A weighting function is then computed for application to spectra of unknown materials. The technique was used to determine calcium by radiative-neutron-capture gamma-ray analysis in the presence of interfering elements, notably titanium, and the results were compared with those for two popular methods of peak area integration. Although linearity of response was similar for the methods, the linear combination technique was much better at rejecting interferences. For analyses involving mixtures of unknown composition the technique consequently offers improved sensitivity. ?? 1972.

  3. Levels of 188Re nucleus populated in thermal neutron capture reaction

    NASA Astrophysics Data System (ADS)

    Běrziņš, J.; Krasta, T.; Simonova, L.; Balodis, M.; Bondarenko, V.; Jentschel, M.; Urban, W.; Tomandl, I.

    2016-03-01

    Levels of 188Re populated in thermal neutron capture reaction with enriched 187Re targets have been studied. Single γ-ray spectrum of 188Re, measured with the high-resolution crystal diffraction spectrometer GAMS5, as well as γγ-coincidence experiments performed with high efficiency Ge detectors, allowed to develop model-independent level scheme of the doubly-odd 188Re nucleus up to ∼ 1.5 MeV excitation energy. Analysis of the established 188Re level scheme in terms of the quasiparticle-plus-rotor model indicates coexistence of axially-deformed and triaxial structures in the energy range above 400 keV.

  4. A case of radiation-induced osteosarcoma treated effectively by boron neutron capture therapy.

    PubMed

    Futamura, Gen; Kawabata, Shinji; Siba, Hiroyuki; Kuroiwa, Toshihiko; Suzuki, Minoru; Kondo, Natsuko; Ono, Koji; Sakurai, Yoshinori; Tanaka, Minoru; Todo, Tomoki; Miyatake, Shin-Ichi

    2014-01-01

    We treated a 54-year-old Japanese female with a recurrent radiation-induced osteosarcoma arising from left occipital skull, by reactor-based boron neutron capture therapy (BNCT). Her tumor grew rapidly with subcutaneous and epidural extension. She eventually could not walk because of cerebellar ataxia. The tumor was inoperable and radioresistant. BNCT showed a marked initial therapeutic effect: the subcutaneous/epidural tumor reduced without radiation damage of the scalp except hair loss and the patient could walk again only 3 weeks after BNCT. BNCT seems to be a safe and very effective modality in the management of radiation-induced osteosarcomas that are not eligible for operation and other treatment modalities. PMID:25366059

  5. Synthesis and Characterization of a Boronated Metallophthalocyanine for Boron Neutron Capture Therapy.

    PubMed

    Kahl, Stephen B.; Li, Jing

    1996-06-19

    Synthesis of the first fully characterized, water-soluble boronated phthalocyanine is reported. Reaction of 4-nitrophthalonitrile with dimethyl malonate in the presence of base yielded dimethyl (3,4-dicyanophenyl)malonate which was converted into dimethyl (3,4-dicyanophenyl)propargylmalonate by sequential treatment with potassium hydroxide and propargyl bromide. Formation of the o-carborane cage was accomplished by reaction of the alkyne with decaborane in acetonitrile at reflux. High-temperature solid state condensation of the resulting o-carboranylphthalonitrile with cobalt(II) chloride followed by ester deprotection and cation exchange provided the water-soluble closo-carbonylphthalocyanine product. The product contains 40 boron atoms (27% boron by weight) and may be useful as a tumor-seeking boron delivery agent for boron neutron capture therapy of cancer. PMID:11666577

  6. Boron neutron capture therapy and radiation synovectomy research at the Massachusetts Institute of Technology Research Reactor

    SciTech Connect

    Zamenhof, R.G.; Nwanguma, C.I.; Wazer, D.E.; Saris, S.; Madoc-Jones, H. ); Sledge, C.B.; Shortkroff, S. )

    1992-04-01

    In this paper, current research in boron neutron capture therapy (BNCT) and radiation synovectomy at the Massachusetts Institute of Technology Research Reactor is reviewed. In the last few years, major emphasis has been placed on the development of BNCT primarily for treatment of brain tumors. This has required a concerted effort in epithermal beam design and construction as well as the development of analytical capabilities for {sup 10}B analysis and patient treatment planning. Prompt gamma analysis and high-resolution track-etch autoradiography have been developed to meet the needs, respectively, for accurate bulk analysis and for quantitative imaging of {sup 10}B in tissue at subcellular resolutions. Monte Carlo-based treatment planning codes have been developed to ensure optimized and individualized patient treatments. In addition, the development of radiation synovectomy as an alternative therapy to surgical intervention is joints that are affected by rheumatoid arthritis is described.

  7. Single step synthesis of nanostructured boron nitride for boron neutron capture therapy

    SciTech Connect

    Singh, Bikramjeet; Singh, Paviter; Kumar, Akshay; Kumar, Manjeet; Thakur, Anup

    2015-05-15

    Nanostructured Boron Nitride (BN) has been successfully synthesized by carbo-thermic reduction of Boric Acid (H{sub 3}BO{sub 3}). This method is a relatively low temperature synthesis route and it can be used for large scale production of nanostructured BN. The synthesized nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analyzer (DTA). XRD analysis confirmed the formation of single phase nanostructured Boron Nitride. SEM analysis showed that the particles are spherical in shape. DTA analysis showed that the phase is stable upto 900 °C and the material can be used for high temperature applications as well boron neutron capture therapy (BNCT)

  8. The Origins of Germanium and the Transition to Neutron-Capture Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Roederer, Ian

    2014-10-01

    We propose to study the element germanium {Ge, Z=32} in cool stars. Ge has a mass that puts it in a transition region from nucleosynthesis occurring in nuclear statistical equilibrium to charged-particle and neutron-capture reactions. Observational constraints on predictions of the nucleosynthesis of Ge are limited, since Ge has only be detected in cool stars with the UV sensitivity of HST. We propose a new ARCHIVE project that will double the number of cool stars with Ge detections. We will use these data to characterize the different Ge production mechanisms over the history of the Galaxy and understand the chemical evolution of this transition element. This will provide a better understanding of the many nucleosynthesis channels that have produced Ge since the earliest epochs of metal production in stars.

  9. Measurement of the thermal neutron capture cross section and the resonance integral of radioactive Hf182

    NASA Astrophysics Data System (ADS)

    Vockenhuber, C.; Bichler, M.; Wallner, A.; Kutschera, W.; Dillmann, I.; Käppeler, F.

    2008-04-01

    The neutron capture cross sections of the radioactive isotope Hf182 (t1/2=8.9×106 yr) in the thermal and epithermal energy regions have been measured by activation at the TRIGA Mark-II reactor of the Atomic Institute of the Austrian Universities in Vienna, Austria, and subsequent γ-ray spectroscopy of Hf183. High values for the thermal (kT=25 meV) cross section σ0=133±10 b and for the resonance integral I0=5850±660 b were found. Additionally, the absolute intensities of the main γ-ray transitions in the decay of Hf182 have been considerably improved.

  10. Effect of boron neutron capture therapy for recurrent anaplastic meningioma: an autopsy case report.

    PubMed

    Kawaji, Hiroshi; Miyatake, Shin-Ichi; Shinmura, Kazuya; Kawabata, Shinji; Tokuyama, Tsutomu; Namba, Hiroki

    2015-01-01

    A 70-year-old woman died of systemic metastasis from anaplastic meningioma and underwent autopsy. The patient underwent twice total removal of the right sphenoid ridge meningioma 2 years ago. The tumor recurred 3 times, and then stereotactic radiotherapy was employed. Boron neutron capture therapy (BNCT) was performed for the fourth local recurrence and an additional new lesion. Proliferative activity of the newly developed meningioma, which had been treated with BNCT only, was significantly lower than that of untreated metastatic liver tumor, as well as that of the meningioma specimen obtained at the second surgery. Our pathological findings demonstrated, for the first time, the therapeutic effect of BNCT on anaplastic meningioma at an early stage (2.5 months). PMID:24807102

  11. Heavy-baryon chiral perturbation theory approach to thermal neutron capture on {sup 3}He

    SciTech Connect

    Lazauskas, Rimantas; Park, Tae-Sun

    2011-03-15

    The cross section for radiative thermal neutron capture on {sup 3}He ({sup 3}He+n{yields}{sup 4}He+{gamma}; known as the hen reaction) is calculated based on heavy-baryon chiral perturbation theory. The relevant M1 operators are derived up to next-to-next-to-next-to-leading order (N{sup 3}LO). The initial and final nuclear wave functions are obtained from the rigorous Faddeev-Yakubovski equations for five sets of realistic nuclear interactions. Up to N{sup 3}LO, the M1 operators contain two low-energy constants, which appear as the coefficients of nonderivative two-nucleon contact terms. After determining these two constants using the experimental values of the magnetic moments of the triton and {sup 3}He, we carry out a parameter-free calculation of the hen cross section. The results are in good agreement with the data.

  12. Boron neutron capture therapy of ocular melanoma and intracranial glioma using p-boronophenylalanine

    SciTech Connect

    Coderre, J.A.; Greenberg, D.; Micca, P.L.; Joel, D.D.; Saraf, S. ); Packer, S. . Div. of Ophthalmology)

    1990-01-01

    During conventional radiotherapy, the dose that can be delivered to the tumor is limited by the tolerance of the surrounding normal tissue within the treatment volume. Boron Neutron Capture Therapy (BNCT) represents a promising modality for selective tumor irradiation. The key to effective BNCT is selective localization of {sup 10}B in the tumor. We have shown that the synthetic amino acid p-boronophenylalanine (BPA) will selectively deliver boron to melanomas and other tumors such as gliosarcomas and mammary carcinomas. Systemically delivered BPA may have general utility as a boron delivery agent for BNCT. In this paper, BNCT with BPA is used in treatment of experimentally induced gliosarcoma in rats and nonpigmented melanoma in rabbits. The tissue distribution of boron is described, as is response to the BNCT. 6 refs., 4 figs., 1 tab.

  13. Boron Neutron Capture Therapy in the Treatment of Locally Recurred Head and Neck Cancer

    SciTech Connect

    Kankaanranta, Leena; Seppaelae, Tiina; Koivunoro, Hanna; Saarilahti, Kauko; Atula, Timo; Collan, Juhani; Salli, Eero; Kortesniemi, Mika; Uusi-Simola, Jouni; Maekitie, Antti; Seppaenen, Marko; Minn, Heikki; Kotiluoto, Petri; Auterinen, Iiro; Savolainen, Sauli; Kouri, Mauri; Joensuu, Heikki

    2007-10-01

    Purpose: Head and neck carcinomas that recur locally after conventional irradiation pose a difficult therapeutic problem. We evaluated safety and efficacy of boron neutron capture therapy (BNCT) in the treatment of such cancers. Methods and Materials: Twelve patients with inoperable, recurred, locally advanced (rT3, rT4, or rN2) head and neck cancer were treated with BNCT in a prospective, single-center Phase I-II study. Prior treatments consisted of surgery and conventionally fractionated photon irradiation to a cumulative dose of 56-74 Gy administered with or without concomitant chemotherapy. Tumor responses were assessed using the RECIST (Response Evaluation Criteria in Solid Tumors) criteria and adverse effects using the National Cancer Institute common toxicity grading v3.0. Intravenously administered boronophenylalanine-fructose (BPA-F, 400 mg/kg) was used as the boron carrier. Each patient was scheduled to be treated twice with BNCT. Results: Ten patients received BNCT twice; 2 were treated once. Ten (83%) patients responded to BNCT, and 2 (17%) had tumor growth stabilization for 5.5 and 7.6 months. The median duration of response was 12.1 months; six responses were ongoing at the time of analysis or death (range, 4.9-19.2 months). Four (33%) patients were alive without recurrence with a median follow-up of 14.0 months (range, 12.8-19.2 months). The most common acute adverse effects were mucositis, fatigue, and local pain; 2 patients had a severe (Grade 3) late adverse effect (xerostomia, 1; dysphagia, 1). Conclusions: Boron neutron capture therapy is effective and safe in the treatment of inoperable, locally advanced head and neck carcinomas that recur at previously irradiated sites.

  14. Subaru/HDS study of CH stars: elemental abundances for stellar neutron-capture process studies

    NASA Astrophysics Data System (ADS)

    Goswami, Aruna; Aoki, Wako; Karinkuzhi, Drisya

    2016-01-01

    A comprehensive abundance analysis providing rare insight into the chemical history of lead stars is still lacking. We present results from high-resolution (R ˜ 50 000) spectral analyses of three CH stars, HD 26, HD 198269 and HD 224959, and, a carbon star with a dusty envelope, HD 100764. Previous studies on these objects are limited by both resolution and wavelength regions and the results differ significantly from each other. We have undertaken to reanalyse the chemical composition of these objects based on high-resolution Subaru spectra covering the wavelength regions 4020-6775 Å. Considering local thermodynamic equilibrium and using model atmospheres, we have derived the stellar parameters, the effective temperatures Teff, surface gravities log g, and metallicities [Fe/H] for these objects. The derived parameters for HD 26, HD 100764, HD 198269 and HD 224959 are (5000, 1.6, -1.13), (4750, 2.0 -0.86), (4500, 1.5, -2.06) and (5050, 2.1, -2.44), respectively. The stars are found to exhibit large enhancements of heavy elements relative to iron in conformity to previous studies. Large enhancement of Pb with respect to iron is also confirmed. Updates on the elemental abundances for several s-process elements (Y, Zr, La, Ce, Nd, Sm and Pb) along with the first-time estimates of abundances for a number of other heavy elements (Sr, Ba, Pr, Eu, Er and W) are reported. Our analysis suggests that neutron-capture elements in HD 26 primarily originate in the s-process while the major contributions to the abundances of neutron-capture elements in the more metal-poor objects HD 224959 and HD 198269 are from the r-process, possibly from materials that are pre-enriched with products of the r-process.

  15. Monte Carlo based treatment planning systems for Boron Neutron Capture Therapy in Petten, The Netherlands

    NASA Astrophysics Data System (ADS)

    Nievaart, V. A.; Daquino, G. G.; Moss, R. L.

    2007-06-01

    Boron Neutron Capture Therapy (BNCT) is a bimodal form of radiotherapy for the treatment of tumour lesions. Since the cancer cells in the treatment volume are targeted with 10B, a higher dose is given to these cancer cells due to the 10B(n,α)7Li reaction, in comparison with the surrounding healthy cells. In Petten (The Netherlands), at the High Flux Reactor, a specially tailored neutron beam has been designed and installed. Over 30 patients have been treated with BNCT in 2 clinical protocols: a phase I study for the treatment of glioblastoma multiforme and a phase II study on the treatment of malignant melanoma. Furthermore, activities concerning the extra-corporal treatment of metastasis in the liver (from colorectal cancer) are in progress. The irradiation beam at the HFR contains both neutrons and gammas that, together with the complex geometries of both patient and beam set-up, demands for very detailed treatment planning calculations. A well designed Treatment Planning System (TPS) should obey the following general scheme: (1) a pre-processing phase (CT and/or MRI scans to create the geometric solid model, cross-section files for neutrons and/or gammas); (2) calculations (3D radiation transport, estimation of neutron and gamma fluences, macroscopic and microscopic dose); (3) post-processing phase (displaying of the results, iso-doses and -fluences). Treatment planning in BNCT is performed making use of Monte Carlo codes incorporated in a framework, which includes also the pre- and post-processing phases. In particular, the glioblastoma multiforme protocol used BNCT_rtpe, while the melanoma metastases protocol uses NCTPlan. In addition, an ad hoc Positron Emission Tomography (PET) based treatment planning system (BDTPS) has been implemented in order to integrate the real macroscopic boron distribution obtained from PET scanning. BDTPS is patented and uses MCNP as the calculation engine. The precision obtained by the Monte Carlo based TPSs exploited at Petten is considered sufficient for the scope of the project. In order to accelerate obtaining an optimised treatment plan, a study is performed which uses linear programming. In this way the beam weights of a particular set of calculated beams are obtained mathematically.

  16. 232Th, 233Pa, and 234U capture cross-section measurements in moderated neutron flux

    NASA Astrophysics Data System (ADS)

    Bringer, O.; Isnard, H.; AlMahamid, I.; Chartier, F.; Letourneau, A.

    2008-07-01

    The Th-U cycle was studied through the evolution of a 100 ?g 232Th sample irradiated in a moderated neutron flux of 8.010 14 n/cm 2/s, intensity close to that of a thermal molten salt reactor. After 43 days of irradiation and 6 months of cooling, a precise mass spectrometric analysis, using both TIMS and MC-ICP-MS techniques, was performed, according to a rigorous methodology. The measured thorium and uranium isotopic ratios in the final irradiated sample were then compared with integral simulations based on evaluated data; an overall good agreement was seen. Four important thermal neutron-capture cross-sections were also extracted from the measurements, 232Th (7.340.21 b), 233Pa (38.341.78 b), 234U (106.123.34 b), and 235U (98.1511.24 b). Our 232Th and 235U results confirmed existing values whereas the cross-sections of 233Pa and 234U (both key parameters) have been redefined.

  17. Dynamic infrared imaging for biological and medical applications in Boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Santa Cruz, Gustavo A.; Gonzlez, Sara J.; Dagrosa, Alejandra; Schwint, Amanda E.; Carpano, Marina; Trivillin, Vernica A.; Boggio, Esteban F.; Bertotti, Jos; Marn, Julio; Monti Hughes, Andrea; Molinari, Ana J.; Albero, Miguel

    2011-05-01

    Boron Neutron Capture Therapy (BNCT) is a treatment modality, currently focused on the treatment of cancer, which involves a tumor selective 10B compound and a specially tuned neutron beam to produce a lethal nuclear reaction. BNCT kills target cells with microscopic selectivity while sparing normal tissues from potentially lethal doses of radiation. In the context of the Argentine clinical and research BNCT projects at the National Atomic Energy Commission and in a strong collaboration with INVAP SE, we successfully implemented Dynamic Infrared Imaging (DIRI) in the clinical setting for the observation of cutaneous melanoma patients and included DIRI as a non invasive methodology in several research protocols involving small animals. We were able to characterize melanoma lesions in terms of temperature and temperature rate-of-recovery after applying a mild cold thermal stress, distinguishing melanoma from other skin pigmented lesions. We observed a spatial and temporal correlation between skin acute reactions after irradiation, the temperature pattern and the dose distribution. We studied temperature distribution as a function of tumor growth in mouse xenografts, observing a significant correlation between tumor temperature and drug uptake; we investigated temperature evolution in the limbs of Wistar rats for a protocol of induced rheumatoid arthritis (RA), DIRI being especially sensitive to RA induction even before the development of clinical signs and studied surface characteristics of tumors, precancerous and normal tissues in a model of oral cancer in the hamster cheek pouch.

  18. Stellar neutron capture cross sections of 20,21,22Ne

    NASA Astrophysics Data System (ADS)

    Heil, M.; Plag, R.; Uberseder, E.; Gallino, R.; Bisterzo, S.; Juseviciute, A.; Käppeler, F.; Lederer, C.; Mengoni, A.; Pignatari, M.

    2014-10-01

    The stellar (n ,γ ) cross sections of the Ne isotopes are important for a number of astrophysical quests, i.e., for the interpretation of abundance patterns in presolar material or with respect to the s -process neutron balance in red giant stars. This paper presents resonance studies of experimental data in the keV range, which had not been fully analyzed before. The analyses were carried out with the R -matrix code sammy. With these results for the resonant part and by adding the components due to direct radiative capture, improved Maxwellian-averaged cross sections (MACS) could be determined. At k T =30 keV thermal energy we obtain MACS values of 240 ±29 ,1263 ±160 , and 53.2 ±2.7 μ barn for 20Ne>, 21Ne, and 22Ne, respectively. In earlier work the stellar rates of 20Ne and 21Ne had been grossly overestimated. 22Ne and 20Ne are significant neutron poisons for the s process in stars because their very small MACS values are compensated by their large abundances.

  19. Electron-capture delayed fission properties of neutron-deficient einsteinium nuclei

    SciTech Connect

    Shaughnessy, Dawn A.

    2000-01-05

    Electron-capture delayed fission (ECDF) properties of neutron-deficient einsteinium isotopes were investigated using a combination of chemical separations and on-line radiation detection methods. {sup 242}Es was produced via the {sup 233}U({sup 14}N,5n){sup 242}Es reaction at a beam energy of 87 MeV (on target) in the lab system, and was found to decay with a half-life of 11 {+-} 3 seconds. The ECDF of {sup 242}Es showed a highly asymmetric mass distribution with an average pre-neutron emission total kinetic energy (TKE) of 183 {+-} 18 MeV. The probability of delayed fission (P{sub DF}) was measured to be 0.006 {+-} 0.002. In conjunction with this experiment, the excitation functions of the {sup 233}U({sup 14}N,xn){sup 247{minus}x}Es and {sup 233}U({sup 15}N,xn){sup 248{minus}x}Es reactions were measured for {sup 243}Es, {sup 244}Es and {sup 245}Es at projectile energies between 80 MeV and 100 MeV.

  20. Induced radioactivity in the blood of cancer patients following Boron Neutron Capture Therapy

    PubMed Central

    Fujiwara, Keiko; Kinashi, Yuko; Takahashi, Tomoyuki; Yashima, Hiroshi; Kurihara, Kouta; Sakurai, Yoshinori; Tanaka, Hiroki; Ono, Koji; Takahashi, Sentaro

    2013-01-01

    Since 1990, Boron Neutron Capture Therapy (BNCT) has been used for over 400 cancer patients at the Kyoto University Research Reactor Institute (KURRI). After BNCT, the patients are radioactive and their 24Na and 38Cl levels can be detected via a Na-I scintillation counter. This activity is predominantly due to 24Na, which has a half-life of 14.96 h and thus remains in the body for extended time periods. Radioactive 24Na is mainly generated from 23Na in the target tissue that is exposed to the neutron beam in BNCT. The purpose of this study is to evaluate the relationship between the radioactivity of blood 24Na following BNCT and the absorbed gamma ray dose in the irradiated field. To assess blood 24Na, 1 ml of peripheral blood was collected from 30 patients immediately after the exposure, and the radioactivity of blood 24Na was determined using a germanium counter. The activity of 24Na in the blood correlated with the absorbed gamma ray doses in the irradiated field. For the same absorbed gamma ray dose in the irradiated field, the activity of blood 24Na was higher in patients with neck or lung tumors than in patients with brain or skin tumors. The reasons for these findings are not readily apparent, but the difference in the blood volume and the ratio of bone to soft tissue in the irradiated field, as well as the dose that leaked through the clinical collimator, may be responsible. PMID:23392825