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1

Database of prompt gamma rays from slow neutron capture forelemental analysis  

SciTech Connect

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.

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

2

Direct thermal neutron capture  

SciTech Connect

We discuss the direct-capture theory pertaining to primary electric dipole (E1) transitions following slow-neutron capture. For light nuclides that we have studied (including /sup 9/Be, /sup 12/C, /sup 13/C, /sup 24/Mg, /sup 25/Mg, /sup 26/Mg, /sup 32/S, /sup 33/S, /sup 34/S, /sup 40/Ca, and /sup 44/Ca), estimates of direct-capture cross sections using optical-model potentials with physically realistic parameters, are in reasonable agreement with the data. Minor disagreements that exist are consistent with extrapolations to light nuclides of generally accepted formulations of compound-nucleus capture. We also discuss the channel-capture approximation which is, in general, a good representation of these cross sections in heavier nuclei particularly if the scattering lengths are not different from the corresponding potential radii. We also draw attention to cases where the use of this formula leads to inaccurate predictions. 9 refs., 1 fig., 2 tab.

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

1987-01-01

3

Neutron capture therapies  

DOEpatents

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.

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

1999-01-01

4

Neutron capture reactions at DANCE  

NASA Astrophysics Data System (ADS)

The Detector for Advanced Neutron Capture Experiments (DANCE) is a 4? 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 ?g) 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 (? = ??/?f) 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.

Bredeweg, T. A.

2008-05-01

5

Neutron capture reactions at DANCE  

SciTech Connect

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.

Bredeweg, T. A. [Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States)

2008-05-12

6

Iodine neutron capture therapy  

NASA Astrophysics Data System (ADS)

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.

Ahmed, Kazi Fariduddin

7

Neutron capture measurements on 62Ni, 63Ni and 197Au and their relevance for stellar nucleosynthesis  

Microsoft Academic Search

Neutron capture reactions in stars are responsible for forming about 99% of the elemental abundances heavier than Fe. Two processes contribute about equally to the overall abundance pattern: the slow neutron capture process (s process) where neutron densities are small and therefore radioactive decay is generally faster than subsequent neutron capture on radionuclides, and the rapid neutron capture process (r

Claudia Lederer

2012-01-01

8

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

NASA Astrophysics Data System (ADS)

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.

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.; Be?vá?, 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.; Krti?ka, 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

9

[Epithermal neutron capture therapy  

SciTech Connect

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.

Not Available

1993-01-01

10

Accelerators and Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

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 1.4×108 cm-2s-1mA-1 was obtained at 4.2 cm from the phantom surface. In order to optimize the design of the neutron production target and the beam shaping assembly extensive Monte Carlo Neutron and Photon (MCNP) simulations have been performed. Neutron fields from a thick LiF and a Li metal target (with both a D2O-graphite and a Al/AlF3-graphite moderator/reflector assembly) were evaluated along the centerline of a head and a whole body phantom. Simulations were carried out for 1.89, 2.0 and 2.3 MeV proton beams. The results show that it is more advantageous to irradiate the target with 2.3 MeV near-resonance protons, instead of very near threshold, because of the higher neutron yield at this energy. On the other hand, the Al/AlF3-graphite exhibits a more efficient performance than D2O in terms of tumor to maximum healthy tissue dose ratio. Treatment times of less than 15 min and tumor control probabilities larger than 98% are obtained for a 50 mA, 2.3 MeV proton beam. The alternative neutron-producing reaction 13C(d,n) is also briefly reviewed. A 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.

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

2002-08-01

11

Neutron dosimetry in boron neutron capture therapy  

SciTech Connect

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.

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

1981-01-01

12

Workshop on neutron capture therapy  

SciTech Connect

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.

Fairchild, R.G.; Bond, V.P. (eds.)

1986-01-01

13

Neutron Capture Reactions for Stockpile Stewardship and Basic Science  

SciTech Connect

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

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

14

Neutron capture autoradiography for a study on boron neutron capture therapy  

Microsoft Academic Search

For the study on boron neutron capture therapy, CR-39 plastic track detectors attached with the whole-body sections of tumor bearing mice infused with 10B were exposed to thermal and cold neutron beams. Neutron capture autoradiographic images obtained by the cold neutron irradiation were extremely superior in quality than that of the thermal neutron beams, which possibly are contaminated by the

K Ogura; A Yamazaki; H Yanagie; M Eriguchi; E. H Lehmann; G Küehne; G Bayon; K Maruyama; H Kobayashi

2001-01-01

15

Benchmarking a surrogate reaction for neutron capture  

SciTech Connect

{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%.

Hatarik, R.; Cizewski, J. A.; Hatarik, A. M.; O'Malley, P. D. [Rutgers University, New Brunswick, New Jersey 08903 (United States); Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Escher, J. E.; Lesher, S. R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Gibelin, J.; Phair, L.; Rodriguez-Vieitez, E. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Goldblum, B. L. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Nuclear Engineering Department, University of California, Berkeley, California 94720 (United States); Swan, T. [Rutgers University, New Brunswick, New Jersey 08903 (United States); University of Surrey, Guildford GU2 7XH, Surrey (United Kingdom); Wiedeking, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2010-01-15

16

Neutron capture therapy for melanoma  

SciTech Connect

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.

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

1988-01-01

17

Applications and misapplications of the channel-capture formalism of direct neutron capture  

SciTech Connect

We discuss the channel-capture approximation of slow neutron direct-capture theory. We show that this approximation gives a generally good representation of the neutron capture cross sections for several electric dipole transitions in a broad range of nuclides from A = 9 to A = 136; these are mostly near-spherical nuclei. Despite this body of agreement, we examine the accuracy we can expect from the simple channel-capture theory. Comparison with calculations of the potential-capture cross section from physically more realistic optical model calculations show that, in general, the channel-capture cross section can be up to approx. =40% in error. In cases where the expected channel-capture cross section is much smaller than the ''hard-sphere'' capture cross-section estimate, the disagreement with potential capture can be much worse than this. Also, in these cases, compound-nucleus capture can be of comparable or greater magnitude. These effects have been shown to completely undermine recent attempts to determine nuclear interaction radii for targets, such as /sup 12/C and /sup 9/Be, by application of the channel-capture formula to capture cross-section data. 20 refs.

Raman, S.; Lynn, J.E.

1985-01-01

18

Boron Neutron Capture Therapy for Cancer  

Microsoft Academic Search

Boron neutron capture therapy (BNCT) bring together two components that when kept separate have only minor effects on normal cells. The first component is a stable isotope of boron (boron 10) that can be concentrated in tumor cells. The second is a beam of low-energy neutrons that produces short-range radiation when absorbed, or captured, by the boron. The combination of

Rolf F. Barth; Albert H. Soloway; Ralph G. Fairchild

1990-01-01

19

Radiative neutron capture by deuterium  

NASA Astrophysics Data System (ADS)

The 2H(n,?)3H reaction has been studied with polarized and unpolarized neutrons of energies ranging from 9 to 14 MeV. Angular distributions of cross section were measured at En(lab)=9.0, 10.8, and 14.0 MeV, ?(90°) was measured at 6.85 MeV, and an analyzing-power angular distribution was measured at 9.0 MeV. The results for ?(theta) agree with the existing 3H(?,n)2H data after detailed balancing. The resulting 3He(?,p)/3H(?,n) ratio for 90° cross sections is 1.1+/-0.15 down to Ex=10.8 MeV. The T-matrix analysis of the data indicates ~3% for the E2 contribution to the capture cross section-comparable to that found earlier for 2H(p,?)3He and in contrast to the predictions [?n(E2)/?p(E2)=1/25] of a two-body direct-capture calculation.

Mitev, G.; Colby, P.; Roberson, N. R.; Weller, H. R.; Tilley, D. R.

1986-08-01

20

Computer simulation of neutron capture therapy.  

E-print Network

Analytical methods are developed to simulate on a large digital computer the production and use of reactor neutron beams f or boron capture therapy of brain tumors. The simulation accounts for radiation dose distributions ...

Olson, Arne Peter

1967-01-01

21

Computer simulation of neutron capture therapy  

E-print Network

Analytical methods are developed to simulate on a large digital computer the production and use of reactor neutron beams f or boron capture therapy of brain tumors. The simulation accounts for radiation dose distributions ...

Olson, Arne Peter

1967-01-01

22

Determination of thermal neutron capture gamma yields.  

E-print Network

A method of analysing Ge(Li) thermal neutron capture gamma spectra to obtain total gamma yields has been developed. Tie method determines both the yields from the well resolved gamma peaks in a spectrum as well as the gamma ...

Harper, Thomas Lawrence

1969-01-01

23

Determination of thermal neutron capture gamma yields  

E-print Network

A method of analysing Ge(Li) thermal neutron capture gamma spectra to obtain total gamma yields has been developed. Tie method determines both the yields from the well resolved gamma peaks in a spectrum as well as the gamma ...

Harper, Thomas Lawrence

1969-01-01

24

Neutron capture in the r-process  

SciTech Connect

Recently we have shown that neutron capture rates on nuclei near stability significantly influence the r-process abundance pattern. We discuss the different mechanisms by which the abundance pattern is sensitive to the capture rates and identify key nuclei whose rates are of particular im- portance. Here we consider nuclei in the A = 130 and A = 80 regions.

Surman, Rebecca [Union College; Mclaughlin, Gail C [North Carolina State University; Mumpower, Matthew [North Carolina State University; Hix, William Raphael [ORNL; Jones, K. L. [University of Tennessee, Knoxville (UTK)

2010-01-01

25

Resonance neutron capture in {sup 58}Ni  

SciTech Connect

High resolution neutron, capture measurements were performed at the Geel linac on an enriched {sup 58}Ni sample over a 1-700 keV energy range. The data were analysed with the R-matrix code REFIT in order to derive resonance parameters and capture areas up to 264 keV. The results are presented, discussed and compared to previous data.

Corvi, F.; Moxon, M.C.; Athanassopulos, K. [CEC-JRC-IRMM, Geel (Belgium)

1994-12-31

26

Neutron capture therapy research in Australia  

SciTech Connect

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.

Allen, B.J. (Australian Nuclear Science and Technology Organisation, Lucas Heights Research Laboratory, Menai)

1989-07-01

27

Neutron-Resonance Capture Analysis of Materials  

SciTech Connect

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.

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

1999-11-14

28

Thermal neutron capture gamma rays from neutron capture in 59Ni and 63Ni  

Microsoft Academic Search

The thermal neutron capture gamma-ray spectra for 60Ni and 64Ni have been observed from a sample previously irradiated to produce long-lived isotopes of 59Ni and 63Ni. New values of the neutron binding energy have been obtained for the compound systems 59Ni, 60Ni, 61Ni, 62Ni, and 64Ni. The gamma-ray spectra for neutron capture by 59Ni and 63Ni are not as strongly

W. M. Wilson; G. E. Thomas; H. E. Jackson

1975-01-01

29

Boron-loaded photographic plates as detectors of slow neutrons  

Microsoft Academic Search

The variations with position in the plate of the emulsion thickness and of the number of slow neutrons recorded per unit area have been determined for a 10 in. × 8 in. × 100 ? boron-loaded plate that had been irradiated uniformly with slow neutrons. The measurements were consistent with a constant concentration of boron throughout the plate and upper

A R Baker

1954-01-01

30

Gadolinium as a Neutron Capture Therapy Agent  

NASA Astrophysics Data System (ADS)

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.

Shih, Jing-Luen Allen

31

Neutron capture measurements for nuclear astrophysics  

NASA Astrophysics Data System (ADS)

Almost all of the heavy elements are produced via neutron capture reactions in a multitude of stellar production sites. The predictive power of the underlying stellar models is currently limited because they contain poorly constrained physics components such as convection, rotation or magnetic fields. Neutron captures measurements on heavy radioactive isotopes provide a unique opportunity to largely improve these physics components, and thereby address important questions of nuclear astrophysics. Such species are branch-points in the otherwise uniquely defined path of subsequent n-captures along the s-process path in the valley of stability. These branch points reveal themselves through unmistakable signatures recovered from pre-solar meteoritic grains that originate in individual element producing stars. Measurements on radioactive isotopes for neutron energies in the keV region represent a stringent challenge for further improvements of experimental techniques. This holds true for the neutron sources, the detection systems and the technology to handle radioactive material. Though the activation method or accelerator mass spectroscopy of the reaction products could be applied in a limited number of cases, Experimental facilities like DANCE at LANL, USA and n-TOF at CERN, Switzerland are addressing the need for such measurements on the basis of the more universal method of detecting the prompt capture gamma-rays, which is required for the application of neutron time-of-flight (TOF) techniques. With a strongly optimized neutron facility at the Rare Isotope Accelerator (RIA) isotopes with half-lives down to tens of days could be investigated, while present facilities require half-lives of a few hundred days. Recent neutron capture experiments on radioactive isotopes with relevance for nuclear astrophysics and possibilities for future experimental setups will be discussed during the talk.

Reifarth, Rene

2005-04-01

32

Neutron capture measurements on 62Ni, 63Ni and 197Au and their relevance for stellar nucleosynthesis  

E-print Network

Neutron capture reactions in stars are responsible for forming about 99% of the elemental abundances heavier than Fe. Two processes contribute about equally to the overall abundance pattern: the slow neutron capture process (s process) where neutron densities are small and therefore radioactive decay is generally faster than subsequent neutron capture on radionuclides, and the rapid neutron capture process (r process) which takes place in environments of high neutron densities, driving the reaction path towards the neutron rich side. The key nuclear physics input for s process studies are stellar neutron capture cross sections, called MACS (Maxwellian-averaged cross section). In the course of this work, dierent reactions relevant to s process nucleosynthesis have been studied. To improve and check existing information, neutron capture cross sections of most stable Fe and Ni isotopes were measured via the time-of-flight technique at the n TOF facility at CERN. This campaign was triggered by a work of Sneden et...

Lederer, Claudia

33

Neutron Slowing Down in a Detector with Absorption Sara A. Pozzi*  

E-print Network

. The results for a capture-gated detector composed of hydrogen, carbon, and boron are discussed. INeutron Slowing Down in a Detector with Absorption Sara A. Pozzi* Oak Ridge National Laboratory, P of an infinite homogeneous mixture. This model is directly applicable to the study of neutron detectors

Pázsit, Imre

34

DYNAMICAL CAPTURE BINARY NEUTRON STAR MERGERS  

SciTech Connect

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.

East, William E.; Pretorius, Frans [Department of Physics, Princeton University, Princeton, NJ 08544 (United States)

2012-11-20

35

The Present Status of Particle Physics with Slow Neutrons  

NASA Astrophysics Data System (ADS)

Slow neutrons are a privileged tool to explore the low-energy high-precision frontier of particle physics. This overview on the present status of neutron-particle physics is intended to serve as a basis for the ensuing discussion of the potential and future development of neutron-particle physics at the European Spallation Source ESS.

Dubbers, Dirk

36

Porphyrins for boron neutron capture therapy  

DOEpatents

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.

Miura, Michiko (Center Moriches, NY); Gabel, Detlef (Bremen, DE)

1990-01-01

37

Energetic neutron emission from ? --capture in deuterium  

NASA Astrophysics Data System (ADS)

The neutron spectrum from 25 to 52 MeV resulting from ? --capture in liquid deuterium was measured by a time-of-flight technique. The spectrum near the end point exhibited an enhancement consistent with the meson-exchange-current calculations.

Lee, Y. K.; Hallman, T. J.; Madansky, L.; Trentalange, S.; Mason, G. R.; Caffrey, A. J.; McIntyre, E. K.; King, T. R.

1987-04-01

38

Microdosimetry for Boron Neutron Capture Therapy  

SciTech Connect

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.

Maughan, R.L.; Kota, C.

2000-09-05

39

Double neutron capture in62Ni  

NASA Astrophysics Data System (ADS)

The ?-radiation following single and double neutron capture in isotopically enriched62Ni was studied at the high flux reactor of the Institut Laue-Langevin, using a pair and Compton suppressed germanium detector. Measurements before and after 170 d of breeding were performed. The ?-ray fluxes through63Ni and64Ni are discussed; several new levels and spin-parity assignments were found. On the basis of the known discrete levels and the low-energy neutron resonances, level density parameters were determined within the Constant Temperature Fermi Gas model. The neutron binding energies were measured as B n (63Ni)=6837.92(18) keV and B n (64Ni)=9657.64(24) keV. The63Ni ( n, ?) cross section for reactor neutrons was measured to be ?=20{-2/+5} b.

Harder, A.; Michaelsen, S.; Jungclaus, A.; Lieb, K. P.; Williams, A. P.; Börner, H. G.; Trautmannsheimer, M.

1992-03-01

40

Neutron Capture Cross Section of ^239Pu  

NASA Astrophysics Data System (ADS)

The ^239Pu(n,?) cross section has been measured at the Los Alamos Neutron Science Center (LANSCE). The Detector for Advanced Neutron Capture Experiments (DANCE) provided a highly segmented 4? measurement of the energy and multiplicity distributions for emitted ?-rays, while a PPAC detected coincidence fission fragments. The simultaneous measurement of (n,?) and (n,f) events resulting from a single sample allowed the (n,?) cross section to be measured as a ratio to fission with reduced systematic uncertainty. Results from the current analysis will be presented.

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

2012-10-01

41

Recent advances in neutron capture therapy (NCT)  

SciTech Connect

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.

Fairchild, R.G.

1985-01-01

42

Neutron detection by measuring capture gammas in a calorimetric approach  

Microsoft Academic Search

The neutron capture detector (NCD) is introduced as a novel detection scheme for thermal and epithermal neutrons that could provide large-area neutron counters by using common detector materials and proven technologies. The NCD is based on the fact that neutron captures are usually followed by prompt gamma cascades, where the sum energy of the gammas equals to the total excitation

Guntram Pausch; Claus-Michael Herbach; Yong Kong; Ralf Lentering; Cristina Plettner; Katja Roemer; Falko Scherwinski; Juergen Stein; Paul Schotanus; Thomas Wilpert

2011-01-01

43

Neutron capture prompt-? activation analysis of foods  

Microsoft Academic Search

The suitability of neutron capture prompt-? activation analysis (PGAA) for multielement analysis of foods was investigated.\\u000a A total of 22 elements was observed in 40 food and mineral supplements. Hydrogen, B, C, N, Na, S, Cl, and K concentrations\\u000a were determined in NIST RM 8431a Mixed Diet and in a wet diet composite made from FDA Total Diet Study collections.

D. L. Anderson; W. C. CUNNINGHAM; E. A. Mackey

1990-01-01

44

Preparation of radioactive rare earth targets for neutron capture study  

SciTech Connect

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.

Miller, G. G. (Geoffrey G.); Rogers, P. S. Z. (Pamela S. Z.); Palmer, P. D. (Phillip D.); Dry, D. E. (Donald E.); Rundberg, R. S. (Robert S.); Fowler, Malcolm M.; Wilhelmy, J. B. (Jerry B.)

2002-01-01

45

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)

46

Accelerator-driven boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

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.

Edgecock, Rob

2014-05-01

47

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

SciTech Connect

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.

Dorn, R.V. III (Mountain States Tumor Institute, Boise, ID (United States) Idaho National Engineering Lab., Idaho Falls, ID (United States))

1994-03-30

48

Neutron Capture Experiments on Unstable Nuclei  

SciTech Connect

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 ac

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

2005-01-15

49

Non-Statistical Effects in Neutron Capture  

SciTech Connect

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.

Koehler, P. E.; Guber, K. H.; Harvey, J. A.; Wiarda, D. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Bredeweg, T. A.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, NM (United States); Reifarth, R. [GSI, Planckstr. 1, 64291 Darmstadt (Germany)

2009-01-28

50

New measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission  

E-print Network

Slow neutron scattering provides quantitative information on the structure and dynamics of materials of interest in physics, chemistry, materials science, biology, geology, and other fields. Liquid hydrogen is 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. In particular the rapid drop of the slow neutron scattering cross section of liquid parahydrogen below 14.5~meV is especially interesting and important. We have measured the total cross section and the scattering cross section for slow neutrons with energies between 0.43~meV and 16.1~meV on liquid hydrogen at 15.6~K using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. At 1~meV this measurement is a factor of 3 below the data from previous work which has been used in the design of liquid hydrogen moderators at slow neutron sources. We describe our measurements, compare them with previous work, and discuss the implications for designing more intense slow neutron sources.

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

2014-12-12

51

Slow neutron distribution in a temperature gradient  

SciTech Connect

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.

Molinari, V.G.; Pollachini, L.

1985-12-01

52

Thermal neutron capture gamma-rays  

SciTech Connect

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.

Tuli, J.K.

1983-01-01

53

Neutron producing target for accelerator based neutron capture therapy  

NASA Astrophysics Data System (ADS)

Pilot innovative accelerator based neutron source for neutron capture therapy of cancer is under construction now at the Budker Institute. One of the main elements of the facility is lithium target producing neutrons via threshold 7Li(p, n)7Be reaction at 10 mA proton beam with energies of 1.915 MeV or 2.5 MeV. In the present report, choice of target was substantiated. The main problems of lithium target were determined to be: 7Be radioactive isotope activation, keeping lithium layer solid, presence of photons resulted from proton inelastic scattering on lithium nuclei, and radiation blistering. The results of thermal testing of target prototype, investigation of radiation blistering and several simulations are presented. It becomes clear that water is preferable for cooling this target, and that the lithium target 10 cm in diameter is able to run up to 25 kW proton beam before melting. The conception of optimal target is proposed: thin and easy to detach metal disk 10 cm in diameter, evaporated with thin layer of pure lithium from the side of proton beam exposure: its back is intensively cooled with turbulent water flow to maintain lithium layer solid. Design of target for the neutron source constructed at BINP is shown. Conceptions of radiation protection and neutrons, ?-rays and ?- particles diagnostics are presented. The immediate plans on obtaining epithermal neutron beam are declared.

Bayanov, B.; Belov, V.; Taskaev, S.

2006-05-01

54

Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crust  

E-print Network

We consider the astrophysical reaction rates for radiative neutron capture reactions ($n,\\gamma$) in the crust of a neutron star. The presence of degenerate neutrons at high densities (mainly in the inner crust) can drastically affect the reaction rates. Standard rates assuming a Maxwell-Boltzmann distribution for neutrons can underestimate the rates by several orders of magnitude. We derive simple analytical expressions for reaction rates at a variety of conditions with account for neutron degeneracy. We also discuss the plasma effects on the outgoing radiative transition channel in neutron radiative capture reactions and show that these effects can also increase the reaction rates by a few orders of magnitude. In addition, using detailed balance, we analyze the effects of neutron degeneracy and plasma physics on reverse ($\\gamma,n$) photodisintegration. We discuss the dependence of the reaction rates on temperature and neutron chemical potential and outline the efficiency of these reactions in the neutron s...

Shternin, P S; Wiescher, M; Yakovlev, D G; 10.1103/PhysRevC.86.015808

2012-01-01

55

Neutron degeneracy and plasma physics effects on radiative neutron captures in neutron star crust  

E-print Network

We consider the astrophysical reaction rates for radiative neutron capture reactions ($n,\\gamma$) in the crust of a neutron star. The presence of degenerate neutrons at high densities (mainly in the inner crust) can drastically affect the reaction rates. Standard rates assuming a Maxwell-Boltzmann distribution for neutrons can underestimate the rates by several orders of magnitude. We derive simple analytical expressions for reaction rates at a variety of conditions with account for neutron degeneracy. We also discuss the plasma effects on the outgoing radiative transition channel in neutron radiative capture reactions and show that these effects can also increase the reaction rates by a few orders of magnitude. In addition, using detailed balance, we analyze the effects of neutron degeneracy and plasma physics on reverse ($\\gamma,n$) photodisintegration. We discuss the dependence of the reaction rates on temperature and neutron chemical potential and outline the efficiency of these reactions in the neutron star crust.

P. S. Shternin; M. Beard; M. Wiescher; D. G. Yakovlev

2012-07-25

56

Neutron Capture Cross Section of 239Pu  

NASA Astrophysics Data System (ADS)

The 239Pu(n,?) 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,?) measurements on 239Pu in the keV region. Fission coincidences were measured with a PPAC and used to characterize the prompt fission ?-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,?) cross section measurement well into the keV region.

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

57

Capture of Cold Neutrons by ^208Pb  

NASA Astrophysics Data System (ADS)

The doubly-magic nucleus ^208Pb has one of the smallest neutron capture cross sections of any stable isotope. The ^208Pb(n,?)^209Pb reaction is the endpoint of the astrophysical s-process, and its rate influences the nucleosynthesis of the lead and bismuth isotopes. The only published experiments on the ^208Pb+n system are resonant measurements, but the non-resonant cross section is predicted to contribute significantly to the reaction rate at astrophysical energies.(T. Rauscher et al)., Phys. Rev. C57 (1998) 2031. We have measured the total ^208Pb(n,?)^209Pb cross section using a cold neutron beam (T_n?20 K) at the NIST Center for Neutron Research. A highly-enriched (>99%) ^208Pb sample was used, and gamma rays were detected using the Prompt-Gamma Activation Analysis Spectrometer. We have found the total cross section for the ^208Pb(n,?)^209Pb reaction to be substantially smaller than previously reported.(J. F. Emery, ORNL Rep. 4343) (1969) 71. These results and the prognosis for future measurements at higher neutron energies will be discussed.

Blackmon, J. C.; Dickens, J. K.; Lindstrom, R. M.; Paul, R. L.

1998-10-01

58

Boron neutron capture therapy for glioblastoma.  

PubMed

Boron neutron capture therapy (BNCT) theoretically allows the preferential destruction of tumor cells while sparing the normal tissue, even if the cells have microscopically spread to the surrounding normal brain. The tumor cell-selective irradiation used in this method is dependent on the nuclear reaction between the stable isotope of boron ((10)B) and thermal neutrons, which release alpha and (7)Li particles within a limited path length (-9 microm) through the boron neutron capture reaction, (10)B(n,alpha)(7)Li. Recent clinical studies of BNCT have focused on high-grade glioma and cutaneous melanoma; however, cerebral metastasis of melanoma, anaplastic meningioma, head and neck tumor, and lung and liver metastasis have been investigated as potential candidates for BNCT. To date, more than 350 high-grade gliomas have been treated in BNCT facilities worldwide. Current clinical BNCT trials for glioblastoma (GBM) have used the epithermal beam at a medically optimized research reactor, and p-dihydroxyboryl-phenylalanine (BPA) and/or sulfhydryl borane Na(2)B(12)H(11)SH (BSH) as the boron delivery agent(s). The results from these rather small phase I/II trials for GBM appear to be encouraging, but prospective randomized clinical trials will be needed to confirm the efficacy of this theoretically promising modality. Improved tumor-targeting boron compounds and optimized administration methods, improved boron drug delivery systems, development of a hospital-based neutron source, and/or other combination modalities will enhance the therapeutic effectiveness of BNCT in the future. PMID:18313207

Yamamoto, Tetsuya; Nakai, Kei; Matsumura, Akira

2008-04-18

59

Neutronic effects on tungsten-186 double neutron capture  

NASA Astrophysics Data System (ADS)

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.

Garland, Marc Alan

60

Research needs for neutron capture therapy  

SciTech Connect

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.

NONE

1995-12-01

61

Slow-neutron scattering by YWW-enriched tungsten  

SciTech Connect

Experiments with polarized and unpolarized neutrons have been carried out to identify the enhanced diffraction scattering of slow neutrons by tungsten which had been discovered previously. The results are reported. This scattering is probably caused by magnetic clusters which form near microscopic cobalt impurities in the tungsten. The slope of the curve of the electric form factor of the neutron is determined from the experimental data available: (partialG/partialqS)/sub q/S = 0 = (-0.0231 +- 0.0009) fmS.

Aleksandrov, Y.A.; Vavra, J.; Vrana, M.; Kulda, I.; Machekhina, T.A.; Mikula, P.; Michalec, R.; Nazarov, V.M.; Okorokov, A.I.; Peresedov, V.F.

1985-07-01

62

Neutron Capture Experiments Using the DANCE Array at Los Alamos  

SciTech Connect

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.

Dashdorj, D. [North Carolina State University, Raleigh, NC 27695 (United States); MonAme Scientific Research Center, Ulaanbaatar (Mongolia); Mitchell, G. E. [North Carolina State University, Raleigh, NC 27695 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Baramsai, B.; Chyzh, A.; Walker, C. [North Carolina State University, Raleigh, NC 27695 (United States); Agvaanluvsan, U. [MonAme Scientific Research Center, Ulaanbaatar (Mongolia); Stanford University, Palo Alto, CA 94305 (United States); Becker, J. A.; Parker, W.; Sleaford, B.; Wu, C. Y. [Lawrence Livermore National Laboratory, Livermore, CA 9455 (United States); Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Krticka, M.; Becvar, F. [Charles University in Prague, CZ-180 00 Prague 8 (Czech Republic)

2009-03-31

63

The Detector for Advanced Neutron Capture Experiments at LANSCE  

SciTech Connect

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.

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. [Los Alamos National Laboratory, Los Alamos NM 87544 (United States); Kaeppeler, F.; Heil, M. [Forschungszentrum Karlsruhe, Karlsruhe, (Germany); Chamberlin, E.P. [Chamberlin Associates, Los Alamos, NM 87544 (United States)

2003-08-26

64

Detector for advanced neutron capture experiments at LANSCE  

SciTech Connect

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

Ullmann, J. L. (John L.); Reifarth, R. (Rene); Haight, Robert C.; Hunt, L. F. (Lloyd F.); O'Donnell, J. M.; Bredeweg, T. A. (Todd A); Wilhelmy, J. B. (Jerry B.); Fowler, Malcolm M.; Vieira, D. J. (David J.); Wouters, J. M. (Jan Marc); Strottman, D.; Kaeppeler, F. (Franz K.); Heil, M.; Chamberlin, E. P. (Edwin P.)

2002-01-01

65

Progress in neutron capture therapy for cancer  

SciTech Connect

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.

Allen, B.J.; Harrington, B.V. [eds.] [Australian Nuclear Science and Technology Organisation, Menai (Australia); Moore, D.E. [ed.] [Sydney Univ. (Australia)

1992-09-01

66

Progress in neutron capture therapy for cancer  

SciTech Connect

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.

Allen, B.J.; Harrington, B.V. (eds.) (Australian Nuclear Science and Technology Organisation, Menai (Australia)); Moore, D.E. (ed.) (Sydney Univ. (Australia))

1992-01-01

67

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

SciTech Connect

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.

Farr, L.E.

1991-12-16

68

Boron thermal/epithermal neutron capture therapy  

SciTech Connect

The development of various particle beams for radiotherapy represents an attempt to improve dose distribution, and to provide high LET radiations which are less sensitive to ambient physical and radiobiological factors such as oxygen tension, cell cycle, and dose rate. In general, a compromise is necessary as effective RBE is reduced in order to spread the dose distribution over the anticipated tumor volume. The approach of delivering stable non-toxic isotopes to tumor, and then activating these atoms subsequently via an external radiation beam has mator advantages; problems associated with high uptake of these isotopes in competing cell pools are obviated, and the general tumor volume can be included in the treatment field of the activating beam. As long as the normal tissues supporting tumor show a low uptake of the isotope to be activated, and as long as the range of the reaction products is short, dose will be restricted to tumor, with a consequent high therapeutic ratio. Neutron Capture Therapy (NCT) is generally carried out by activating boron-10 with low energy neutrons. 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.., or one cell diameter, a situation that is optimal for cell killing. Significant advantages may be gained by using the NCT procedure in conjunction with improved tissue penetration provided with epithermal or filtered beams, and new compounds showing physiological binding to tumor.

Fairchild, R.G.

1982-01-01

69

Neutron Capture Cross Sections of 236U and 234U  

SciTech Connect

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.

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. [Los Alamos National Laboratory (United States); Kronenberg, A. [Oak Ridge National Laboratory (United States)

2006-03-13

70

Neutron capture therapy with deep tissue penetration using capillary neutron focusing  

DOEpatents

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.

Peurrung, Anthony J. (Richland, WA)

1997-01-01

71

Neutron Capture Experiments on Unstable Nuclei  

SciTech Connect

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.

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

2003-12-16

72

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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.

Miura, Michiko (Hampton Bays, NY); Slatkin, Daniel N. (Southold, NY)

1997-08-05

73

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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.

Miura, M.; Slatkin, D.N.

1997-03-18

74

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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.

Miura, Michiko (Hampton Bays, NY); Slatkin, Daniel N. (Southold, NY)

1997-03-18

75

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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.

Miura, Michiko (Hampton Bays, NY); Slatkin, Daniel N. (Southold, NY)

1995-10-03

76

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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.

Miura, M.; Slatkin, D.N.

1997-08-05

77

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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.

Miura, M.; Slatkin, D.N.

1995-10-03

78

Neutron Capture Gamma-Ray Libraries for Nuclear Applications  

SciTech Connect

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.

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

79

Neutron Capture Reactions on lu Isotopes at Dance  

NASA Astrophysics Data System (ADS)

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.

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

80

Neutron Capture Rates and r-PROCESS Nucleosynthesis  

NASA Astrophysics Data System (ADS)

Simulations of r-process nucleosynthesis require nuclear physics information for thousands of neutron-rich nuclear species from the line of stability to the neutron drip line. While arguably the most important pieces of nuclear data for the r-process are the masses and ? decay rates, individual neutron capture rates can also be of key importance in setting the final r-process abundance pattern. Here we consider the influence of neutron capture rates in forming the A ~ 80 and rare earth peaks.

Surman, R. A.; Mumpower, M. R.; McLaughlin, G. C.; Sinclair, R.; Hix, W. R.; Jones, K. L.

2013-03-01

81

Sensitivity studies for the weak r process: neutron capture rates  

SciTech Connect

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.

Surman, R., E-mail: surmanr@union.edu [Department of Physics and Astronomy, Union College, Schenectady, NY 12308 (United States); Mumpower, M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)] [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Sinclair, R.; Jones, K. L. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States)] [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Hix, W. R. [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States) [Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); McLaughlin, G. C. [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)] [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)

2014-04-15

82

Radiobiology of normal rat lung in Boron Neutron Capture Therapy  

E-print Network

Boron Neutron Capture Therapy (BNCT) is a binary cancer radiation therapy that utilizes biochemical tumor cell targeting and provides a mixed field of high and low Linear Energy Transfer (LET) radiation with differing ...

Kiger, Jingli Liu

2006-01-01

83

Heterogeneous Neutron Capture Record of the Norton County Enstatite Achondrite  

NASA Astrophysics Data System (ADS)

Large and heterogeneous isotopic variations of Sm and Gd due to neutron capture reactions caused by cosmic-ray irradiation were found in chemical and mineral separates from the Norton County meteorite.

Hidaka, H.; Yoneda, S.

2012-09-01

84

Sensitivity studies for the weak r process: neutron capture rates  

NASA Astrophysics Data System (ADS)

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.

Surman, R.; Mumpower, M.; Sinclair, R.; Jones, K. L.; Hix, W. R.; McLaughlin, G. C.

2014-04-01

85

Neutron detection by measuring capture gammas in a calorimetric approach  

NASA Astrophysics Data System (ADS)

The neutron capture detector (NCD) is introduced as a novel detection scheme for thermal and epithermal neutrons that could provide large-area neutron counters by using common detector materials and proven technologies. The NCD is based on the fact that neutron captures are usually followed by prompt gamma cascades, where the sum energy of the gammas equals to the total excitation energy of typically 6-9 MeV. This large sum energy is measured in a calorimetric approach and taken as the signature of a neutron capture event. An NCD consists of a neutron converter, comprising of constituents with large elemental neutron capture cross-section like cadmium or gadolinium, which is embedded in common scintillator material. The scintillator must be large and dense enough to absorb with reasonable probability a portion of the sum energy that exceeds the energy of gammas emitted by common (natural, medical, industrial) radiation sources. An energy window, advantageously complemented with a multiplicity filter, then discriminates neutron capture signals against background. The paper presents experimental results obtained at the cold-neutron beam of the BER II research reactor, Helmholtz-Zentrum Berlin, and at other neutron sources with a prototype NCD, consisting of four BGO crystals with embedded cadmium sheets, and with a benchmark configuration consisting of two separate NaI(Tl) detectors. The detector responses are in excellent agreement with predictions of a simulation model developed for optimizing NCD configurations. NCDs could be deployed as neutron detectors in radiation portal monitors (RPMs). Advanced modular scintillation detector systems could even combine neutron and gamma sensitivity with excellent background suppression at minimum overall expense.

Pausch, Guntram; Herbach, Claus-Michael; Kong, Yong; Lentering, Ralf; Plettner, Cristina; Roemer, Katja; Scherwinski, Falko; Stein, Juergen; Schotanus, Paul; Wilpert, Thomas

2011-10-01

86

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

SciTech Connect

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.

Farr, L.E.

1991-12-16

87

Cosmogenic neutron-capture-produced nuclides in stony meteorites  

SciTech Connect

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.

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

1985-01-01

88

NSTAR—A capture gated plastic neutron detector  

NASA Astrophysics Data System (ADS)

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 12×20×(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 =21.7±0.2 ?s and a detection efficiency of ?=26±3% 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.

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

2011-02-01

89

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

SciTech Connect

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.

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. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States); Agvaanluvsan, U.; Becker, J. A. [Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94551 (United States); Baker, J. D. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States); Bayarbadrahk, B.; Chyzh, A.; Dashdorj, D. [North Carolina State University, Department of Physics, Raleigh, NC 27695 (United States); Reifarth, R. [Gesellschaft fuer Schwerionenforschung (GSI), Plankstrasse 1, 64291 Darmstadt (Germany)

2009-03-10

90

Slow cortical potentials capture decision processes during temporal discounting  

PubMed Central

Various neuroimaging studies have detected brain regions involved in discounting the value of temporally delayed rewards. This study used slow cortical potentials (SCPs) to elaborate the time course of cognitive processing during temporal discounting. Depending on their strength of discounting, subjects were categorised as low and high impulsive. Low impulsives, but not high impulsives, showed faster reaction times for making decisions when the delayed reward was of high amount than when it was of low amount. Both low impulsives and high impulsives chose the delayed reward more often when its amount was high than when it was low, but this behavior was more pronounced for low impulsives. Moreover, only low impulsives showed more negative SCPs for low than for high amounts. All three measures indicated that only low impulsives experienced extended conflict for delayed low amounts than for high amounts. Additionally, the SCPs of low impulsives were more sensitive to the delay of the delayed reward than those of high impulsives, extending seconds after the response. This indicates that they continued evaluating their choices even after the decision. Altogether, the present study demonstrated that SCPs are sensitive to decision-related resource allocation during inter-temporal decision-making. Resource allocation depended both on the choice situation and on impulsivity. Furthermore, the time course of SCPs suggested that decision-related processes occurred both prior to and after the response. PMID:23279189

Oswald, Felix; Sailer, Uta

2013-01-01

91

Levels in 237U studied by resonant neutron capture  

Microsoft Academic Search

Primary and secondary gamma rays in 237U from resonant neutron capture in 236U have been measured with the fast chopper facility, the neutron monochromator, and 2- and 24-keV neutron beam filters. A level scheme was constructed including 27 levels with spin and parity assignments. Rotational band members of the Nilsson configurations [631?], [622?], [624?], [631?], [633?], and [501?] and of

T. von Egidy; J. A. Cizewski; C. M. McCullagh; S. S. Malik; M. L. Stelts; R. E. Chrien; D. Breitig; R. F. Casten; W. R. Kane; G. J. Smith

1979-01-01

92

Neutron capture therapy with deep tissue penetration using capillary neutron focusing  

DOEpatents

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.

Peurrung, A.J.

1997-08-19

93

Neutron capture reactions on Lu isotopes at DANCE  

NASA Astrophysics Data System (ADS)

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.

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

94

Cosmogenic neutron-capture-produced nuclides in stony meteorites  

NASA Technical Reports Server (NTRS)

The complete neutron-flux results and production rates for Cl-36, Ni-59, and Co-60 in stony meteorites of various radii and composition are presented. The relative neutron source strengths and neutron production-versus-depth profiles were determined by using calculated H-3 production rates. The absolute source strengths were normalized to that determined for the moon by Woolum et al. (1975). The energy spectrum of the source neutrons and the neutron transport calculations, which employed the ANISN computer code, were similar to those used for the moon by Lingenfelter et al. (1972). The production rates of the three radionuclides were determined as a function of depth in various spherical meteoroids from the calculated equilibrium neutron-flux distributions and from energy-dependent neutron-capture cross sections. Rates for producing these radionuclides by spallation reactions were also calculated.

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

1986-01-01

95

Neutron capture strategy and technique developments for GNEP  

SciTech Connect

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.

Couture, Aaron Joseph [Los Alamos National Laboratory

2008-01-01

96

A Monte Carlo investigation of the dosimetric properties of monoenergetic neutron beams for neutron capture therapy  

Microsoft Academic Search

A Monte Carlo simulation study has been carried out to investigate the suitability of neutron beams of various energies for therapeutic efficacy in boron neutron capture therapy. The dosimetric properties of unidirectional, monoenergetic neutron beams of varying diameters in two different phantoms (a right-circular cylinder and an ellipsoid) made of brain-equivalent material were examined. The source diameter was varied from

J. C. Yanch; X. L. Zhou; G. L. Brownell

1991-01-01

97

An epithermal neutron beam for neutron capture therapy at the Missouri University Research Reactor  

Microsoft Academic Search

In this paper a facility designed to produce a beam of epithermal neutrons for neutron capture therapy is discussed whereby a moderator of AlâOâ plus aluminum is placed near the core of the 10-MW Missouri University Research Reactor. This moderator shifts the fast neutrons into the epithermal energy range before they exit toward the patient position. This beam replaces the

R. M. Brugger; J. L. A. Shih; H. B. Liu

1992-01-01

98

Gradual Di#usive Capture: Slow Death by Many Mosquito Bites  

E-print Network

Gradual Di#usive Capture: Slow Death by Many Mosquito Bites S. Redner Santa Fe Institute, 1399 Hyde by another di#using particle (a ``mosquito'') with fixed di#usivity Dm . Each time the mosquito meets#usivity of the mosquito is unchanged. The mosquito is also displaced by a small distance ±a with respect to the man after

Redner, Sidney

99

Neutron Capture and Fission Measurement on ^238Pu at DANCE  

NASA Astrophysics Data System (ADS)

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 ?-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-?g 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 ?g in order to reduce ?-background load on PPAC. This was the first such measurement in a laboratory environment. The absolute ^238Pu(n,?) cross section is presented together with the prompt ?-ray multiplicity in the ^238Pu(n,f) reaction.

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

100

Sublethal and potentially lethal damage repair on thermal neutron capture therapy  

SciTech Connect

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.

Utsumi, H.; Ichihashi, M.; Kobayashi, T.; Elkind, M.M. (Kyoto Univ. (Japan))

1989-07-01

101

Neutron capture rates on radioactive nuclides - DANCE  

NASA Astrophysics Data System (ADS)

The nucleosynthesis of the elements including their stellar sites is one of the most interesting nuclear physics challenges. Information on reaction rates for neutron induced reactions have a direct impact on existing stellar models. Except for the stable isotopes, very few neutron-induced reactions in the energy range of interest have been measured to date. DANCE measurements on stable and unstable isotopes can provide many of the missing key reactions that are needed to understand the nucleosynthesis of the heavy elements, which is illustrated at the example of the 151Sm(n,?) reaction.

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

2006-10-01

102

Progress on the Europium Neutron-Capture Study using DANCE  

SciTech Connect

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.

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

103

Accelerator-based epithermal neutron beam design for neutron capture therapy  

Microsoft Academic Search

Recent interest in the production of epithermal neutrons for use in boron neutron capture therapy (BNCT) has prompted 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 DâO moderator,

J. C. Yanch; X. Zhou; R. E. Shefer; R. E. Klinkowstein

1992-01-01

104

Design of an accelerator-based epithermal neutron beam for boron neutron capture therapy  

Microsoft Academic Search

Recent interest in the production of epithermal neutrons for use in boron neutron capture therapy (BNCT) has prompted an investigation into the feasibility of generating such neutrons with a tandem cascade accelerator. Accelerator-produced neutrons in the range of roughly 200--800 keV are generated in a lithium compound target via the ⁷Li(p,n)⁷Be nuclear reaction in a tandem cascade accelerator currently under

J. C. Yanch; X. L. Zhou; G. L. Brownell; R. E. Shefer; R. E. Klinkowstein

1990-01-01

105

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

SciTech Connect

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.

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. [Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Stoyer, M. A.; Wu, C. Y.; Becker, J. A.; Haslett, R. J.; Henderson, R. A. [Lawrence Livermore National Laboratory, Livermore, CA, 94550 (United States)

2009-01-28

106

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

SciTech Connect

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.

Jandel, Marian [Los Alamos National Laboratory

2008-01-01

107

Neutron Capture and Fission Measurements on Actinides at DANCE  

NASA Astrophysics Data System (ADS)

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 ?-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,?) cross section will be presented, which was measured using DANCE alone and also is the first such measurement in a laboratory environment.

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

108

Continuum quasiparticle random phase approximation for astrophysical direct neutron capture reaction of neutron-rich nuclei  

E-print Network

We 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 of O(1 keV) - O(1 MeV), relevant for the rapid neutron-capture process of nucleosynthesis. We begin with the photo-absorption cross section and the E1 strength function, then, in order to apply the reciprocity theorem, we decompose the cross section into partial cross sections corresponding to different channels of one- and two-neutron emission decays of photo-excited states. Numerical example is shown for the photo-absorption of $^{142}$Sn and the neutron capture of $^{141}$Sn.

Masayuki Matsuo

2014-10-31

109

Radiative Neutron Capture on Carbon-14 in Effective Field Theory  

E-print Network

The cross section for radiative capture of neutron on carbon-14 is calculated using the model-independent formalism of halo effective field theory. The dominant contribution from E1 transition is considered, and the cross section is expressed in terms of elastic scattering parameters of the effective range expansion. Contributions from both resonant and non-resonant interaction are calculated. Significant interference between these leads to a capture contribution that deviates from simple Breit-Wigner resonance form.

Gautam Rupak; Lakma Fernando; Akshay Vaghani

2012-04-19

110

Radiative Neutron Capture on Carbon-14 in Effective Field Theory  

E-print Network

The cross section for radiative capture of neutron on carbon-14 is calculated using the model-independent formalism of halo effective field theory. The dominant contribution from E1 transition is considered, and the cross section is expressed in terms of elastic scattering parameters of the effective range expansion. Contributions from both resonant and non-resonant interaction are calculated. Significant interference between these leads to a capture contribution that deviates from simple Breit-Wigner resonance form.

Rupak, Gautam; Vaghani, Akshay

2012-01-01

111

Stellar neutron capture on 180 Tam . II. Defining the s -process contribution to nature's rarest isotope  

NASA Astrophysics Data System (ADS)

The contribution of the slow neutron capture process ( s process) to the solar 180 Tam abundance has been investigated on the basis of new experimental information. Measured neutron capture cross sections of 180 Tam and the corresponding Maxwellian averaged ( n,? ) rates were important for defining the s abundance of 180 Tam , and the result of a recent photoactivation experiment was providing an estimate of its half-life at the temperatures of the s -process site. Following the s -process network with stellar evolutionary models from the premain sequence through the asymptotic giant branch phase, it was found that the produced 180 Tam survives the high temperatures during He shell flashes because of the fast convective mixing, which provides an efficient means for transporting freshly synthesized matter into cooler, outer zones. Accordingly, 180 Tam appears to be predominantly of s -process origin.

Käppeler, F.; Arlandini, C.; Heil, M.; Voss, F.; Wisshak, K.; Reifarth, R.; Straniero, O.; Gallino, R.; Masera, S.; Travaglio, C.

2004-05-01

112

Neutron capture cross section of {sup 241}Am  

SciTech Connect

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.

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. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Agvaanluvsan, U.; Parker, W. E.; Wu, C. Y.; Becker, J. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2008-09-15

113

Neutron capture cross section standards for BNL 325, Fourth Edition  

SciTech Connect

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.

Holden, N.E.

1981-01-01

114

Neutron detection based on capture-gamma sensing and calorimetry  

NASA Astrophysics Data System (ADS)

Passive radiation detection systems have been developed to screen passengers, vehicles, and cargo for illicit radioactive sources by measuring gamma and neutron signatures with separate, specialized sensors. The paper introduces a novel concept combining neutron and gamma sensing in a single detector, thus reducing the overall expense. Low-cost converter media capture thermal neutrons and commute neutron flux in energetic gammas, which are then detected by a common gamma detector. Energy signals above 3 MeV indicate the neutron captures. Two prototype systems are presented: (1) The NCD-BGO, a segmented 655 ml BGO scintillator with embedded Cd absorber, demonstrated an intrinsic thermal-neutron detection efficiency of about 50%. (2) The PVTNG, comprising 75 l of PVT scintillator complemented with PVC panels, exhibited a neutron sensitivity of 1.9 cps/ng of 252Cf, thus almost meeting the corresponding requirement for Radiation Portal Monitors. Moreover, an unconventional construction of scintillator and light readout, combined with innovative electronics and proper detector stabilization, improved the gamma detector performance noticeably and enabled nuclide identification.

Pausch, Guntram; Herbach, Claus-Michael; Mitchell, Dean; Lentering, Ralf; Stein, Juergen

2012-06-01

115

Valence neutron capture. gamma. -ray spectrum in /sup 54/Fe  

SciTech Connect

Neutron capture ..gamma..-ray spectra have been measured from the 7.76-keV s-wave and the 9.48-, 11.2-, and 14.4-keV p-wave resonances in /sup 54/Fe. The 7.76-keV resonance spectrum is in excellent agreement with valence model predictions.

Raman, S.; Slaughter, G.G.; Wells, J.C. Jr.; Allen, B.J.

1980-07-01

116

Proceedings of the first international symposium on neutron capture therapy  

SciTech Connect

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.

Fairchild, R.G.; Brownell, G.L. (eds.)

1982-01-01

117

Neutron-Capture Element Abundances in Halo Stars  

E-print Network

We present new abundance observations of neutron-capture elements in Galactic stars. These include new Hubble Space Telescope (HST) detections of the elements Ge, Zr and Pt in a group of 11 halo stars. Correlations between these elements and Eu (obtained with ground-based observations), and with respect to metallicity, are also presented.

John J. Cowan; Christopher Sneden

2004-09-22

118

Mixed field dosimetry of epithermal neutron beams for boron neutron capture therapy at the MITR-II research reactor  

Microsoft Academic Search

During the past several years, there has been growing interest in Boron Neutron Capture Therapy (BNCT) using epithermal neutron beams. The dosimetry of these beams is challenging. The incident beam is comprised mostly of epithermal neutrons, but there is some contamination from photons and fast neutrons. Within the patient, the neutron spectrum changes rapidly as the incident epithermal neutrons scatter

Ronald D. Rogus; O. K. Harling; J. C. Yanch

1994-01-01

119

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

NASA Technical Reports Server (NTRS)

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.

Lugmair, G. W.; Marti, K.

1972-01-01

120

Current status of fast-neutron-capture calculations  

SciTech Connect

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.

Gardner, D.G.

1982-04-15

121

General Electric PETtrace cyclotron as a neutron source for boron neutron capture therapy  

Microsoft Academic Search

This research investigates the use of a PETtrace cyclotron produced by General Electric (GE) as a neutron source for boron neutron capture therapy (BNCT). The GE PETtrace was chosen for this investigation because this type of cyclotron is popular among nuclear pharmacies and clinics in many countries; it is compact and reliable; it produces protons with energies high enough to

Andrey Bosko

2005-01-01

122

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

123

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

NASA Astrophysics Data System (ADS)

The capture cross sections and capture ?-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 ?-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 ?-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 ?-ray spectra of 104,105Pd were also derived by un-folding the respective observed capture ?-ray pulse-height spectra.

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

2013-03-01

124

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

SciTech Connect

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.

Cizewski, J. A. [Rutgers University; Jones, K. L. [University of Tennessee; Kozub, R. L. [Tennessee Technological University; Pain, Steven D [ORNL; Peters, W. A. [Rutgers University; Adekola, Aderemi S [ORNL; Allen, J. [Rutgers University; Bardayan, Daniel W [ORNL; Becker, J. [Lawrence Livermore National Laboratory (LLNL); Blackmon, Jeff C [ORNL; Chae, K. Y. [University of Tennessee; Chipps, K. [Colorado School of Mines, Golden; Erikson, Luke [Colorado School of Mines, Golden; Gaddis, A. L. [Furman University; Harlin, Christopher W [ORNL; Hatarik, Robert [Rutgers University; Howard, Joshua A [ORNL; Jandel, M. [Los Alamos National Laboratory (LANL); Johnson, Micah [ORNL; Kapler, R. [University of Tennessee; Krolas, W. [University of Warsaw; Liang, J Felix [ORNL; Livesay, Jake [ORNL; Ma, Zhanwen [ORNL; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Matthews, C. [Rutgers University; Moazen, Brian [University of Tennessee; Nesaraja, Caroline D [ORNL; O'Malley, Patrick [Rutgers University; Patterson, N. P. [University of Surrey, UK; Paulauskas, Stanley [University of Tennessee; Pelham, T. [University of Surrey, UK; Pittman, S. T. [University of Tennessee, Knoxville (UTK); Radford, David C [ORNL; Rogers, J. [Tennessee Technological University; Schmitt, Kyle [University of Tennessee; Shapira, Dan [ORNL; ShrinerJr., J. F. [Tennessee Technological University; Sissom, D. J. [Tennessee Technological University; Smith, Michael Scott [ORNL; Swan, T. P. [University of Surrey, UK; Thomas, J. S. [Rutgers University; Vieira, D. J. [Los Alamos National Laboratory (LANL); Wilhelmy, J. B. [Los Alamos National Laboratory (LANL); Wilson, Gemma L [ORNL

2009-04-01

125

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

NASA Astrophysics Data System (ADS)

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

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

126

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

SciTech Connect

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.

Yano, Takatomi; Ou, I.; Izumi, T.; Yamaguchi, R.; Mori, T.; Sakuda, M. [Department of Physics, Okayama University, Okayama, 700-8530 (Japan)

2012-11-12

127

Measurements of Neutron Capture Cross-Section for Tantalum at the Neutron Filtered Beams  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of tantalum have been measured for the neutron energies 2 and 59 keV using the WWR-M Kyiv Research Reactor (KRR) of the Institute for Nuclear Research of the National Academy of Science of Ukraine. The cross sections of 181Ta (n, ?) 182Ta reaction were obtained by the activation method using a gamma-spectrometer with Ge(Li)-detector. The obtained neutron capture cross sections were compared with the known experimental data from database EXFOR/CSISRS and the ENDF libraries.

Gritzay, Olena; Libman, Volodymyr

2009-08-01

128

Moderated 252Cf neutron energy spectra in brain tissue and calculated boron neutron capture dose.  

PubMed

While there is significant clinical experience using both low- and high-dose (252)Cf brachytherapy, combination therapy using (10)B for neutron capture therapy-enhanced (252)Cf brachytherapy has not been performed. Monte Carlo calculations were performed in a brain phantom (ICRU 44 brain tissue) to evaluate the dose enhancement predicted for a range of (10)B concentrations over a range of distances from a clinical (252)Cf source. These results were compared to experimental measurements and calculations published in the literature. For (10)B concentrations neutron capture dose enhancement was small in comparison to the (252)Cf fast neutron dose. PMID:15308139

Rivard, Mark J; Zamenhof, Robert G

2004-11-01

129

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

NASA Astrophysics Data System (ADS)

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.

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

130

Quantitative interpretation of pulsed neutron capture logs: Part 2 --Inversion of measurements in thinly bedded  

E-print Network

Quantitative interpretation of pulsed neutron capture logs: Part 2 -- Inversion of measurements have developed an inversion method to reduce shoulder-bed effects on pulsed neutron capture (PNC) logs, rendering them spatially smooth. In the specific case of pulsed neutron capture (PNC) logs, neighboring

Torres-Verdín, Carlos

131

Review of Livermore-Led Neutron Capture Studies Using DANCE  

SciTech Connect

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.

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

132

Accelerator Based Neutron Beams for Neutron Capture Therapy  

SciTech Connect

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.

Yanch, Jacquelyn C.

2003-04-11

133

Neutron radiative capture methods for surface elemental analysis  

USGS Publications Warehouse

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.

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

1970-01-01

134

Design of an accelerator-based epithermal neutron beam for boron neutron capture therapy  

SciTech Connect

Recent interest in the production of epithermal neutrons for use in boron neutron capture therapy (BNCT) has prompted an investigation into the feasibility of generating such neutrons with a tandem cascade accelerator. Accelerator-produced neutrons in the range of roughly 200--800 keV are generated in a lithium compound target via the {sup 7}Li(p,n){sup 7}Be nuclear reaction in a tandem cascade accelerator currently under development by Science Research Laboratory, Somerville, MA. Details of the design of the proton accelerator and operating characteristics will be too energetic for use in neutron capture therapy, a detailed dosimetric study was undertaken to determine the energy, or range of energies most suitable for NCT. This study was carried out using three-dimensional Monte Carlo transport calculations; results are discussed briefly here. Once the most suitable range of energies for BNCT was determined, it was then possible to design an appropriate moderator assembly to shift the energy of the neutrons down to the therapeutically useful levels. Such an assembly has been designed with the aid of computer simulation; calculations of treatment parameters indicate that the accelerator neutron beam can provide dose rates and advantage depths comparable to currently available reactor beams for neutron capture therapy. 10 refs., 5 figs.

Yanch, J.C.; Zhou, X.L.; Brownell, G.L. (Massachusetts Inst. of Tech., Cambridge, MA (United States)); Shefer, R.E.; Klinkowstein, R.E. (Science Research Lab., Inc., Somerville, MA (United States))

1990-01-01

135

How Accurately Can We Calculate Neutrons Slowing Down In Water ?  

SciTech Connect

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.

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

2006-03-30

136

Neutron-capture Nucleosynthesis in the First Stars  

NASA Astrophysics Data System (ADS)

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. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile, and The McDonald Observatory of The University of Texas at Austin.

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

2014-04-01

137

Stellar neutron capture cross sections of the Gd isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector, which was improved by replacing crystals with high ? background and by introducing a pierced crystal at zero degrees with respect to the beam axis. These changes resulted in a significantly increased efficiency for capture events. The main experimental problem was that the samples of the two s isotopes 152Gd and 154Gd showed only relatively low enrichment. Nevertheless, the spectroscopic quality of the BaF2 detector allowed evaluation of the corresponding corrections for isotopic impurities reliably. The cross section ratios could be determined with an overall uncertainty of typically 1%, an improvement by factors of five to ten compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. The new stellar cross sections were used for an updated analysis of the s-process reaction flow in the mass region between samarium and gadolinium, which is characterized by branchings at 151Sm, 154Eu, and 155Eu. With the classical approach, the s-process temperature could be constrained corresponding to a range of thermal energies between kT=28 and 33 keV. The 152Gd production in low mass stars was found to depend strongly on the neutron freeze-out at the end of the helium shell burning episodes.

Wisshak, K.; Voss, F.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Uhl, M.; Reffo, G.

1995-11-01

138

Stellar neutron capture cross sections of Pr and Dy isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 141Pr,160Dy,161Dy,162Dy,163Dy, and 164Dy have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector. The cross sections were determined relative to the gold standard. For the first time the correction for undetected capture events was completely obtained from experimental information, using capture cascades derived from measurements with an analog-to-digital converter system. The cross section ratios could be determined with an overall uncertainty of 1-1.5 %, an average improvement compared to previous measurements by a factor 4. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=8 keV and 100 keV. For most of the isotopes there is reasonable agreement with recent evaluations, but discrepancies of ~20% were obtained for 160Dy and 164Dy. The experimental data were complemented by statistical model calculations in order to describe the cross section enhancements in the stellar environment. The astrophysical implications of the present data include the quest for the origin of 160Dy, the decomposition of the Dy abundances in the respective s- and r-process contributions, branchings of the s-process chain at the terrestrially stable isotopes 157Gd and 163Dy, and the isotopically anomalous dysprosium in meteoritic inclusions.

Voss, F.; Wisshak, K.; Arlandini, C.; Käppeler, F.; Kazakov, L.; Rauscher, T.

1999-02-01

139

Stellar neutron capture cross sections of the Lu isotopes  

SciTech Connect

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.

Wisshak, K.; Voss, F.; Kaeppeler, F.; Kazakov, L. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Institute for Physics and Power Engineering, Obninsk, Kaluga-Region (Russian Federation)

2006-01-15

140

Modern alchemy: Fred Hoyle and element building by neutron capture  

NASA Astrophysics Data System (ADS)

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.

Burbidge, E. Margaret

141

Thermal neutron capture cross sections of the palladium isotopes  

SciTech Connect

Precise thermal neutron capture {gamma}-ray cross sections {sigma}{sub {gamma}} were measured for all elements with Z=1-83,90, and 92, for He and Pm, at the Budapest Reactor. These data were evaluated with additional information from the literature to generate the Evaluated Gamma-ray Activation File (EGAF). Isotopic radiative neutron cross sections can be deduced from the total transition cross section feeding the ground state, {sigma}{sub 0}={sigma}{sigma}{sub {gamma}}(GS) if the decay scheme is complete. The EGAF file contains partial {gamma}-ray cross sections for all stable palladium isotopes. None of these decay schemes are complete, although in each case transitions de-exciting low-lying levels are known. We have performed Monte Carlo simulations of the palladium thermal neutron capture decay schemes using the computer code DICEBOX. The simulated populations of low low-lying levels are normalized to the measured {sigma}{sub {gamma}} values from EGAF and the total radiative neutron cross section {sigma}{sub 0} is obtained. The {sigma}{sub 0} values derived for the palladium isotopes agree well with previous measurements and were in several cases more precise. Complementary use of {gamma}-ray cross-section data and Monte Carlo calculations has proven effective in determining both the palladium total radiative cross sections and new nuclear structure information.

Krticka, M. [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Prague 8 (Czech Republic); North Carolina State University, Raleigh, NC 27695 (United States); Firestone, R. B. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); McNabb, D. P.; Sleaford, B.; Agvaanluvsan, U. [Lawrence Livermore National Laboratory, L-414, 7000 East Avenue, Livermore, CA 94551 (United States); Belgya, T.; Revay, Z. S. [Institute of Isotope and Surface Chemistry, H-1525, Budapest (Hungary)

2008-05-15

142

Improved neutron capture cross section of Pu239  

NASA Astrophysics Data System (ADS)

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.

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

143

Quantitative neutron capture resonance analysis verified with instrumental neutron activation analysis  

NASA Astrophysics Data System (ADS)

The newly developed elemental analysis technique Neutron Resonance Capture Analysis (NRCA) was verified by analyzing a prehistoric bronze arrowhead with both NRCA and Instrumental Activation Analysis (INAA). In NRCA, elements are identified through their neutron resonance capture energies as determined through detection of prompt capture gamma-rays as a function of time of flight. The quantification is obtained from the resonance peak areas. Corrections are required for neutron-energy-dependent dead time and self-shielding, the latter also depending on Doppler broadening. The analysis program REFIT, of which the intended use is the determination of the resonance parameters, was used to this end. The agreement observed between INAA and NRCA results indicates that the NRCA results obtained are accurate.

Blaauw, M.; Postma, H.; Mutti, P.

2003-06-01

144

Thermal neutron capture cross sections of the potassium isotopes  

NASA Astrophysics Data System (ADS)

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 [Révay and Molnár, Radiochimica ActaRAACAP0033-823010.1524/ract.91.6.361.20027 91, 361 (2003); Molnár, Révay, 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)=2.28±0.04 b, ?0(40K)=90±7 b, and ?0(41K)=1.62±0.03 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.

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

2013-02-01

145

Development of a boron neutron capture enhanced fast neutron therapy beam  

NASA Astrophysics Data System (ADS)

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.

Sweezy, Jeremy Ed

146

Position-sensitive detection of slow neutrons: Survey of fundamental principles  

SciTech Connect

This paper sets forth the fundamental principles governing the development of position-sensitive detection systems for slow neutrons. Since neutrons are only weakly interacting with most materials, it is not generally practical to detect slow neutrons directly. Therefore all practical slow neutron detection mechanisms depend on the use of nuclear reactions to convert'' the neutron to one or more charged particles, followed by the subsequent detection of the charged particles. The different conversion reactions which can be used are discussed, along with the relative merits of each. This is followed with a discussion of the various methods of charged particle detection, how these lend themselves to position-sensitive encoding, and the means of position encoding which can be applied to each case. Detector performance characteristics which may be of importance to the end user are discussed and related to these various detection and position-encoding mechanisms.

Crawford, R.K.

1992-01-01

147

Position-sensitive detection of slow neutrons: Survey of fundamental principles  

SciTech Connect

This paper sets forth the fundamental principles governing the development of position-sensitive detection systems for slow neutrons. Since neutrons are only weakly interacting with most materials, it is not generally practical to detect slow neutrons directly. Therefore all practical slow neutron detection mechanisms depend on the use of nuclear reactions to ``convert`` the neutron to one or more charged particles, followed by the subsequent detection of the charged particles. The different conversion reactions which can be used are discussed, along with the relative merits of each. This is followed with a discussion of the various methods of charged particle detection, how these lend themselves to position-sensitive encoding, and the means of position encoding which can be applied to each case. Detector performance characteristics which may be of importance to the end user are discussed and related to these various detection and position-encoding mechanisms.

Crawford, R.K.

1992-07-01

148

Stellar neutron capture cross sections of the Gd isotopes.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 152Gd, 154Gd, 155Gd, 156Gd, 157Gd, and 158Gd were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p, n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector The main experimental problem was that the samples of the two s-only isotopes 152Gd and 154Gd showed only relatively low enrichment, but the spectroscopic quality of the BaF2 detector allowed to determine the resulting corrections for isotopic impurities reliably. The cross section ratios could be determined with an overall uncertainty of typically 1%, an improvement by factors of five to ten compared to existing data. Severe discrepancies were found with respect to previous results. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 10 keV and 100 keV. The new stellar cross sections were used for an updated analysis of the s-process reaction flow in the mass region between samarium and gadolinium, which is characterized by branchings at 151Sm, 154Eu, and 155Eu. With the classical approach, the s-process temperature could be constrained corresponding to a range of thermal energies between kT - 28 keV and 33 keV. The 152Gd production in low mass stars was found to depend strongly on the neutron freeze-out at the end of the helium shell burning episodes.

Wisshak, K.; Voss, F.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Uhl, M.; Reffo, G.

1995-05-01

149

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

SciTech Connect

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.

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

150

New horizons for therapy based on the boron neutron capture reaction.  

PubMed

Boron neutron capture therapy (BNCT) is currently undergoing clinical trials in the USA, Japan and The Netherlands with patients afflicted with deadly brain cancer (glioblastoma multiforme) or melanoma. This therapy relies on a binary process in which the capture of a slow neutron by a 10B nucleus leads to an energetic nuclear fission reaction, with the formation of 7Li3+ and 4He2+ and accompanied by about 2.4 MeV of energy. The fleeting 7Li3+ and 4He2+ travel a distance of only about the diameter of one cell, and they are deadly to any cell in which they have been produced. Research in progress is concerned with the development of advanced boron agents and neutron sources, other than nuclear reactors, for the treatment of a variety of cancer types using novel 10B delivery methods. Non-malignant diseases such as rheumatoid arthritis offer additional opportunities for BNCT. The entire BNCT area awaits commercialization. PMID:9572059

Hawthorne, M F

1998-04-01

151

Near-Ultraviolet Observations of CS 29497-030: New Constraints on Neutron-Capture Nucleosynthesis Processes  

NASA Astrophysics Data System (ADS)

Employing spectra obtained with the new Keck I HIRES near-UV-sensitive detector, we have performed a comprehensive chemical composition analysis of the binary blue metal-poor star CS 29497-030. Abundances for 29 elements and upper limits for an additional seven have been derived, concentrating on elements largely produced by means of neutron-capture nucleosynthesis. Included in our analysis are the two elements that define the termination point of the slow neutron-capture process, lead and bismuth. We determine an extremely high value of [Pb/Fe]=+3.65+/-0.07 (?=0.13) from three features, supporting the single-feature result obtained in previous studies. We detect Bi for the first time in a metal-poor star. Our derived Bi/Pb ratio is in accord with those predicted from the most recent FRANEC calculations of the slow neutron-capture process in low-mass asymptotic giant branch (AGB) stars. We find that the neutron-capture elemental abundances of CS 29497-030 are best explained by an AGB model that also includes very significant amounts of pre-enrichment of rapid neutron-capture process material in the protostellar cloud out of which the CS 29497-030 binary system formed. Mass transfer is consistent with the observed [Nb/Zr]~0. Thus, CS 29497-030 is both an r+s and ``extrinsic AGB'' star. Furthermore, we find that the mass of the AGB model can be further constrained by the abundance of the light odd-element Na. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Ivans, Inese I.; Sneden, Christopher; Gallino, Roberto; Cowan, John J.; Preston, George W.

2005-07-01

152

[Principles of therapy with fission neutrons and boron neutron capture therapy for radioresistant head-neck malignancies].  

PubMed

Neutron therapy has proven to be clinically useful in cases of advanced, slow-growing radioresistant head and neck carcinoma. Therapeutic effects might be based on direct DNA damaging and thus immediate cell-killing, on the generation of free oxygen radicals and, among others, on the fact that heavy particle radiation is said to be less dependent on the presence of oxygen than gamma rays, i.e. on a lower oxygen enhancement ratio (OER). The smaller difference in reaction between oxygenated and nonoxygenated cells could entail advantages as well as disadvantages, depending on the characteristics of the tumor cell population and of the normal tissue. It is therefore essential to select patients and tumours with an expectedly high therapeutic gain factor. Fission neutrons for tumour therapy: As evaluated by several in vitro and in vivo studies (11/13) the biological efficiency (RBE) of the RENT (Reactor Neutron Therapy) beam in Munich seems to be among the highest of all clinically used neutron beams. For a single dose range between 2 and 8 Gy the RBE for chronic radiation damage is relatively small (2). Consequently, patients with recurrent or metastatic carcinomas of the head and neck are treated with a single dose of 200-250 cGy after previous surgery and/or combined radiochemotherapy. The main limitation of fission neutrons is the small penetration depth. Possibilities of clinical implementation of boron neutron capture therapy (BNCT) in otorhinolaryngology: In near surface tumours it is possible to administer high doses of 10boron not selectively, i.e. no selective tumour-seeking compound is needed. Animal experiments with intratumoural injection of 10boron glycine have shown a strong effect on tumour growth delay (18).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2222692

Clasen, B

1990-08-01

153

Neutron Capture Measurements and Resonance Analysis of Dysprosium Y.R. Kang,1  

E-print Network

Neutron Capture Measurements and Resonance Analysis of Dysprosium Y.R. Kang,1 M.W. Lee,1 T.I. Ro,2 The electron linear accelerator facility at the Rensselaer Polytechnic Institute was used to measure neutron capture yields of dysprosium with the time-of-flight method in the neutron energy region from 10 eV to 1

Danon, Yaron

154

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

SciTech Connect

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.

Hatarik, R.; Cizewski, J. A.; O'Malley, P. D. [Rutgers University, Department of Physics and Astronomy, New Brunswick, NJ 08901 (United States); Bernstein, L. A.; Burke, J. T.; Lesher, S. R. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Gibelin, J. D.; Phair, L. W. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Swan, T. [Rutgers University, Department of Physics and Astronomy, New Brunswick, NJ 08901 (United States); University of Surrey, Physics Department, Guildford GU2 7XH, Surrey (United Kingdom)

2008-04-17

155

Towards epithermal Boron Neutron Capture Therapy for cancer  

SciTech Connect

Progress in the treatment of local disseminating cancer such as high grade brain tumours is poor, and the ability to kill individual cancer cells in the midst of normal cells has not been achieved. Binary therapies hold the most promise of this, and of these Boron Neutron Capture Therapy is the most advanced. Epithermal neutron beams are essential for outpatient treatment of high grade brain tumours and these are now installed and being characterised in Europe and the USA, and are at the design stage in Australia. These beams would allow the bilateral irradiation of the entire brain, and as such are ideally suited for the prophylactic therapy of subclinical metastases. When coupled with appropriate cancer affined boron compounds, therapeutic ratios of 2-3 should be achieved. At present the only source of an epithermal neutron beam is a nuclear reactor. The Euratom reactor at Petten and the Brookhaven Medical Reactor have been retrofitted with filters to produce an epithermal neutron beam. These beams have been characterised and used in dose escalation studies with dogs to study normal tissue tolerance using borocaptate (BSH). Another beam is available at the MIT medical research reactor. Clinical trials at Petten for glioblastoma with BSH and at MIT using boronophenylalanine for melanoma metastases to the extremities are expected to commence this year. The state of the art of reactor based BNCT is reviewed and the potential for a major change in the prognosis of local control of disseminating cancer is explored.

Allen, B.J. [Australian Nuclear Science and Technology Organisation, Menai (Australia)

1994-12-31

156

Design of a boron neutron capture enhanced fast neutron therapy assembly  

SciTech Connect

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.

Wang, Zhonglu; /Georgia Tech

2006-08-01

157

Neutron Capture gamma ENDF libraries for modeling and identification of neutron sources  

SciTech Connect

There are a number of inaccuracies and data omissions with respect to gammas from neutron capture in the ENDF libraries used as field reference information and by modeling codes used in JTOT. As the use of Active Neutron interrogation methods is expanded, these shortfalls become more acute. A new, more accurate and complete evaluated experimental database of gamma rays (over 35,000 lines for 262 isotopes up to U so far) from thermal neutron capture has recently become available from the IAEA. To my knowledge, none of this new data has been installed in ENDF libraries and disseminated. I propose to upgrade libraries of {sup 184,186}W, {sup 56}Fe, {sup 204,206,207}Pb, {sup 104}Pd, and {sup 19}F the 1st year. This will involve collaboration with Richard Firestone at LBL in evaluating the data and installing it in the libraries. I will test them with the transport code MCNP5.

Sleaford, B

2007-10-29

158

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)

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 ˜1×109 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.

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

2002-10-01

159

A Monte Carlo investigation of the dosimetric properties of monoenergetic neutron beams for neutron capture therapy  

SciTech Connect

A Monte Carlo simulation study has been carried out to investigate the suitability of neutron beams of various energies for therapeutic efficacy in boron neutron capture therapy. The dosimetric properties of unidirectional, monoenergetic neutron beams of varying diameters in two different phantoms (a right-circular cylinder and an ellipsoid) made of brain-equivalent material were examined. The source diameter was varied from 0.0 to 20.0 cm; neutron energies ranged from 0.025 eV up to 800 keV, the maximum neutron energy generated by a tandem cascade accelerator using 2.5-MeV protons in a {sup 7}Li(p,n){sup 7}Be reaction. Such a device is currently under investigation for use as a neutron source for boron neutron capture therapy. The simulation studies indicate that the maximum effective treatment depth (advantage depth) in the brain is 10.0 cm and is obtainable with a 10-keV neutron beam. A useful range of energies, defined as those neutron energies capable of effectively treating to a depth of 7 cm in brain tissue, is found to be 4.0 eV to 40.0 keV. Beam size is shown not to affect advantage depth as long as the entire phantom volume is used in determining this depth. Dose distribution in directions parallel to and perpendicular to the beam direction are shown to illustrate this phenomenon graphically as well as to illustrate the differences in advantage depth and advantage ratio and the contribution of individual dose components to tumor dose caused by the geometric differences in phantom shape.

Yanch, J.C.; Zhou, X.L.; Brownell, G.L. (Massachusetts Inst. of Tech., Cambridge (USA))

1991-04-01

160

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

161

Fission reactor neutron sources for neutron capture therapy--a critical review.  

PubMed

The status of fission reactor-based neutron beams for neutron capture therapy (NCT) is reviewed critically. Epithermal neutron beams, which are favored for treatment of deep-seated tumors, have been constructed or are under construction at a number of reactors worldwide. Some of the most recently constructed epithermal neutron beams approach the theoretical optimum for beam purity. Of these higher quality beams, at least one is suitable for use in high through-put routine therapy. It is concluded that reactor-based epithermal neutron beams with near optimum characteristics are currently available and more can be constructed at existing reactors. Suitable reactors include relatively low power reactors using the core directly as a source of neutrons or a fission converter if core neutrons are difficult to access. Thermal neutron beams for NCT studies with small animals or for shallow tumor treatments, with near optimum properties have been available at reactors for many years. Additional high quality thermal beams can also be constructed at existing reactors or at new, small reactors. Furthermore, it should be possible to design and construct new low power reactors specifically for NCT, which meet all requirements for routine therapy and which are based on proven and highly safe reactor technology. PMID:12749699

Harling, Otto K; Riley, Kent J

2003-01-01

162

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

DOEpatents

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.

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

163

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

DOEpatents

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.

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

1999-05-11

164

Boron neutron capture therapy for malignant melanoma: An experimental approach  

SciTech Connect

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.

Larsson, B.S.; Larsson, B.; Roberto, A. (Uppsala Univ. (Sweden))

1989-07-01

165

Benchmark on neutron capture extracted from (d,p) reactions  

NASA Astrophysics Data System (ADS)

Direct neutron capture reactions play an important role in nuclear astrophysics and applied physics. Since for most unstable short-lived nuclei it is not possible to measure the (n,?) cross sections, (d,p) reactions have been used as an alternative indirect tool. We analyze simultaneously 48Ca(d,p)49Ca reactions at deuteron energies of 2,13,19, and 56 MeV and the thermal (n,?) reaction at 25 meV. We include results for the ground state and the first excited state of Ca49. From the low-energy (d,p) reaction, the neutron asymptotic normalization coefficient (ANC) is determined. Using this ANC, we extract the spectroscopic factor (SF) from the higher energy (d,p) data and the (n,?) data. The SF obtained through the 56-MeV (d,p) data are less accurate but consistent with those from the thermal capture. We show that to have a similar dependence on the single-particle parameters as in the (n,?), the (d,p) reaction should be measured at 30 MeV.

Mukhamedzhanov, A. M.; Nunes, F. M.; Mohr, P.

2008-05-01

166

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

SciTech Connect

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.

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

167

Low Energy Accelerator-Based Neutron Sources for Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

An epithermal neutron beam design for an accelerator -based neutron source for neutron capture therapy (NCT) has been studied. Calculation shows that, of many possible neutron-producing reactions, the Li-7(p,n)Be-7 and H-3(p,n)He -3 reactions are the more promising reactions for producing high neutron yields for NCT. The total neutron yield from the Li-7(p,n)Be-7 and H-3(p,n)He-3 reactions are 1.5 times 10^{-4} and 2.5 times 10^ {-4} neutrons/proton with 2.5 and 1.77 MeV protons, respectively. For a 20 mA proton beam (typical current has been achieved with Radio Frequency Quadrupole accelerators so far), the total neutron yield would be about 1.8 times 10^ {13} and 3.2 times 10^{13} neutrons/sec for the Li-7(p,n)Be-7 and H-3(p,n)He-3 reactions, respectively. The reactions must be coupled with a moderator to reduce the energy of the neutrons to an acceptable range. A three -dimensional Monte Carlo code (MCNP) was used to predict neutron flux and neutron and gamma doses. The modified moderator assembly consists of a cylindrical moderator surrounded by a cylindrical reflector. Li-6 with 0.05% atomic concentration was determined to be the concentration in the moderator and reflector, for mitigating the production of gamma rays by removing thermal neutrons. For the Li -7(p,n)Be-7 reaction and a 20 mA proton beam, BeO (20 cm thick, 25 cm diameter cylinder) and MgO (85 cm diameter cylinder) appear to be the optimum selection of moderator and reflector materials. The useful neutron (neutron energy > 1 eV) flux in air, calculated at the irradiation position, is 2.0 times 10^9 n/cm^2/s. For the H-3(p,n)He-3 reaction, rm Al_2O _3 as moderator (34 cm thick) and also as reflector material gave the best performance. The useful neutron flux, calculated in air at the irradiation position, is 2.4 times 10^9 n/cm^2/s.

Wu, Hsinshun (Terry).

168

Computational Dosimetry and Treatment Planning Considerations for Neutron Capture Therapy  

SciTech Connect

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.

Nigg, David Waler

2003-03-01

169

Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy  

SciTech Connect

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.

Herrera, Maria S.; Gonzalez, Sara J. [Comision National de Energia Atomica and CONICET, Buenos Aires (Argentina); Minsky, Daniel M.; Kreiner, Andres J. [Comision National de Energia Atomica and CONICET, Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, UNSAM, Buenos Aires (Argentina)

2010-08-04

170

Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

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.

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

2010-08-01

171

Thermal neutron capture cross sections and neutron separation energies for 23Na(n,?)  

NASA Astrophysics Data System (ADS)

Prompt thermal neutron capture ?-ray cross sections ?? were measured for the 23Na(n,?) reaction with guided cold neutron beams at the Budapest Reactor. The 24Na ?-ray cross sections were internally standardized with a stoichiometric NaCl target by using standard 35Cl(n,?)36Cl ?-ray cross sections. Transitions were assigned to levels in 24Na based primarily upon the known nuclear structure information from the literature, producing a nearly complete neutron capture decay scheme. The total radiative thermal neutron cross section ?0 was determined from the sum of prompt ?-ray cross section populating the ground state as 0.540 (3) b, and from the activation ?-ray cross sections for the decay of 24Na as 0.542 (3) b. The isomer cross section ?0 (23Nam, t1/2=20.20ms)=0.501(3) b and the 24Na neutron separation energy Sn=6959.352(18) keV were also determined in these experiments. New level spins and parities were proposed on the basis of new transition assignments and the systematics of reduced transition probabilities for the primary ? rays.

Firestone, R. B.; Revay, Zs.; Belgya, T.

2014-01-01

172

Alanine and TLD coupled detectors for fast neutron dose measurements in neutron capture therapy (NCT).  

PubMed

A method was investigated to measure gamma and fast neutron doses in phantoms exposed to an epithermal neutron beam designed for neutron capture therapy (NCT). The gamma dose component was measured by TLD-300 [CaF2:Tm] and the fast neutron dose, mainly due to elastic scattering with hydrogen nuclei, was measured by alanine dosemeters [CH3CH(NH2)COOH]. The gamma and fast neutron doses deposited in alanine dosemeters are very near to those released in tissue, because of the alanine tissue equivalence. Couples of TLD-300 and alanine dosemeters were irradiated in phantoms positioned in the epithermal column of the Tapiro reactor (ENEA-Casaccia RC). The dosemeter response depends on the linear energy transfer (LET) of radiation, hence the precision and reliability of the fast neutron dose values obtained with the proposed method have been investigated. Results showed that the combination of alanine and TLD detectors is a promising method to separate gamma dose and fast neutron dose in NCT. PMID:15353722

Cecilia, A; Baccaro, S; Cemmi, A; Colli, V; Gambarini, G; Rosi, G; Scolari, L

2004-01-01

173

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

NASA Astrophysics Data System (ADS)

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 6·1010 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.

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

2014-12-01

174

Maxwellian Averaged Neutron Capture Cross Sections in 56Fe and 57Fe  

NASA Astrophysics Data System (ADS)

Measurements of the keV-neutron capture cross sections and radiative ?-ray spectrum of 56Fe and 57Fe are performed based on a 7Li(p,n)7Be reaction neutron source. The incident neutron spectrum on a capture sample is measured by means of a time-of-flight (TOF) method with a 6Li-glass detector. The radiative capture ?-rays emitted from an iron (56Fe or 57Fe) or standard gold (197Au) sample are detected by a large anti-Compton NaI(Tl) spectrometer covered with a heavy shield. The capture yields of samples are obtained by applying a pulse-height weighting technique to the corresponding capture ?-ray pulse-height spectrum. The Maxwellian averaged neutron capture cross sections of 56Fe and 57Fe are derived according to the present capture cross section results.

Wang, Tao-Feng; Lee, Man-Woo; Kim, Guin-Yun; Ro, Tae-Ik; Kang, Yeong-Rok; Igashira, Masayuki; Katabuchi, Tatsuya

2014-09-01

175

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

176

Scissors mode of Gd nuclei studied from resonance neutron capture  

SciTech Connect

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.

Kroll, J.; Baramsai, B.; Becker, J. A. [Charles University in Prague, CZ-180 00 Prague 8 (Czech Republic); North Carolina State University, Raleigh, NC 27695 (United States) and Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); and others

2012-10-20

177

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

SciTech Connect

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.

Nigg, David W. [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States)] [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States); Wemple, Charles A. [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States)] [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States); Risler, Ruedi [University of Washington, Department of Radiation Oncology, P.O. Box 356043, Seattle, Washington 98195 (United States)] [University of Washington, Department of Radiation Oncology, P.O. Box 356043, Seattle, Washington 98195 (United States); Hartwell, John K. [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States)] [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States); Harker, Yale D. [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States)] [Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, Idaho 83415 (United States); Laramore, George E. [University of Washington, Department of Radiation Oncology, P.O. Box 356043, Seattle, Washington 98195 (United States)] [University of Washington, Department of Radiation Oncology, P.O. Box 356043, Seattle, Washington 98195 (United States)

2000-02-01

178

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

SciTech Connect

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.

Kozub, R. L. [Tennessee Technological University; Arbanas, Goran [ORNL; Adekola, A. S. [Ohio University, Athens; Bardayan, Daniel W [ORNL; Blackmon, Jeffery C [Louisiana State University; Chae, Kyung Yuk [ORNL; Chipps, K. [Colorado School of Mines, Golden; Cizewski, J. A. [Rutgers University; Erikson, Luke [Colorado School of Mines, Golden; Hatarik, Robert [Rutgers University; Hix, William Raphael [ORNL; Jones, K. L. [University of Tennessee, Knoxville (UTK); Krolas, W. [University of Warsaw; Liang, J Felix [ORNL; Ma, Z. [University of Tennessee, Knoxville (UTK); Matei, Catalin [Oak Ridge Associated Universities (ORAU); Moazen, Brian [University of Tennessee, Knoxville (UTK); Nesaraja, Caroline D [ORNL; Pain, Steven D [ORNL; Shapira, Dan [ORNL; ShrinerJr., J. F. [Tennessee Technological University; Smith, Michael Scott [ORNL; Swan, T. P. [University of Surrey, UK

2012-01-01

179

HD209621: abundances of neutron-capture elements  

NASA Astrophysics Data System (ADS)

High-resolution spectra obtained from the Subaru Telescope High Dispersion Spectrograph have been used to update the stellar atmospheric parameters and metallicity of the star HD209621. We have derived a metallicity of [Fe/H] = -1.93 for this star, and have found a large enhancement of carbon and of heavy elements, with respect to iron. Updates on the elemental abundances of four s-process elements (Y, Ce, Pr, Nd) along with the first estimates of abundances for a number of other heavy elements (Sr, Zr, Ba, La, Sm, Eu, Er, Pb) are reported. The stellar atmospheric parameters, the effective temperature, Teff, and the surface gravity, logg (4500K, 2.0), are determined from local thermodynamic equilibrium analysis using model atmospheres. Estimated [Ba/Eu] = +0.35, places the star in the group of CEMP-(r+s) stars; however, the s-elements abundance pattern seen in HD209621 is characteristic of CH stars; notably, the second-peak s-process elements are more enhanced than the first-peak s-process elements. HD209621 is also found to show a large enhancement of the third-peak s-process element lead (Pb) with [Pb/Fe] = +1.88. The relative contributions of the two neutron-capture processes, r and s, to the observed abundances are examined using a parametric model-based analysis, which hints that the neutron-capture elements in HD209621 primarily originate in s-process. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and at HCT, IAO, Hanle, India. E-mail: aruna@iiap.res.in (AG); aoki.wako@nao.ac.jp (WA)

Goswami, Aruna; Aoki, Wako

2010-05-01

180

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

181

Dose monitoring for boron neutron capture therapy using a reactor-based epithermal neutron beam.  

PubMed

The aims of this study were (i) to determine the variation with time of the relevant beam parameters of a clinical reactor-based epithermal neutron beam for boron neutron capture therapy (BNCT) and (ii) to test a monitoring system for its applicability to monitor the dose delivered to the dose specification point in a patient treated with BNCT. For this purpose two fission chambers covered with Cd and two GM counters were positioned in the beam-shaping collimator assembly of the epithermal neutron beam. The monitor count rates were compared with in-phanton reference measurements of the thermal neutron fluence rate, the gamma-ray dose rate and the fast neutron dose rate, at a constant reactor power, over a period of 2 years. Differences in beam output, defined as the thermal neutron fluence rate at 2 cm depth in a phantom, of up to 15% were observed between various reactor cycles. A decrease in beam output of about 5% was observed in each reactor cycle. An unacceptable decrease of 50% in beam output due to malfunctioning of the beam filter assembly was detected. For safe and accurate treatment of patients, on-line monitoring of the beam is essential. Using the calibrated monitor system, the standard uncertainty in the total dose at depth due to variations with time of the beam output parameters has been reduced to a clinically acceptable value of 1% (one standard deviation). PMID:8971969

Raaijmakers, C P; Nottelman, E L; Konijnenberg, M W; Mijnheer, B J

1996-12-01

182

Boron analysis and boron imaging in biological materials for Boron Neutron Capture Therapy (BNCT)  

Microsoft Academic Search

Boron Neutron Capture Therapy (BNCT) is based on the ability of the stable isotope 10B to capture neutrons, which leads to a nuclear reaction producing an alpha- and a 7Li-particle, both having a high biological effectiveness and a very short range in tissue, being limited to approximately one cell diameter. This opens the possibility for a highly selective cancer therapy.

Andrea Wittig; Jean Michel; Raymond L. Moss; Finn Stecher-Rasmussen; Heinrich F. Arlinghaus; Peter Bendel; Pier Luigi Mauri; Saverio Altieri; Ralf Hilger; Piero A. Salvadori; Luca Menichetti; Robert Zamenhof; Wolfgang A. G. Sauerwein

2008-01-01

183

Tidal capture of primordial black holes by neutron stars  

NASA Astrophysics Data System (ADS)

The fraction of primordial black holes (PBHs) of masses 1017- 1026 g in the total amount of dark matter may be constrained by considering their capture by neutron stars (NSs), which leads to the rapid destruction of the latter. The constraints depend crucially on the capture rate which, in turn, is determined by the energy loss by a PBH passing through a NS. Two alternative approaches to estimate the energy loss have been used in the literature: the one based on the dynamical friction mechanism, and another on tidal deformations of the NS by the PBH. The second mechanism was claimed to be more efficient by several orders of magnitude due to the excitation of particular oscillation modes reminiscent of the surface waves. We address this disagreement by considering a simple analytically solvable model that consists of a flat incompressible fluid in an external gravitational field. In this model, we calculate the energy loss by a PBH traversing the fluid surface. We find that the excitation of modes with the propagation velocity smaller than that of PBH is suppressed, which implies that in a realistic situation of a supersonic PBH the large contributions from the surface waves are absent and the above two approaches lead to consistent expressions for the energy loss.

Defillon, Guillaume; Granet, Etienne; Tinyakov, Peter; Tytgat, Michel H. G.

2014-11-01

184

On tidal capture of primordial black holes by neutron stars  

E-print Network

The fraction of primordial black holes (PBHs) of masses $10^{17} - 10^{26}$ g in the total amount of dark matter may be constrained by considering their capture by neutron stars (NSs), which leads to the rapid destruction of the latter. The constraints depend crucially on the capture rate which, in turn, is determined by the energy loss by a PBH passing through a NS. Two alternative approaches to estimate the energy loss have been used in the literature: the one based on the dynamical friction mechanism, and another on tidal deformations of the NS by the PBH. The second mechanism was claimed to be more efficient by several orders of magnitude due to the excitation of particular oscillation modes reminiscent of the surface waves. We address this disagreement by considering a simple analytically solvable model that consists of a flat incompressible fluid in an external gravitational field. In this model, we calculate the energy loss by a PBH traversing the fluid surface. We find that the excitation of modes with the propagation velocity smaller than that of PBH is suppressed, which implies that in a realistic situation of a supersonic PBH the large contributions from the surface waves are absent and the above two approaches lead to consistent expressions for the energy loss.

Guillaume Defillon; Etienne Granet; Petr Tinyakov; Michel H. G. Tytgat

2014-09-01

185

Malignant melanoma cure by selective thermal neutron capture therapy  

SciTech Connect

Thermal neutrons are easily absorbed by the nonradioactive isotope /sup 10/B, resulting in the emission of alpha particles and lithium atoms, which release an energy of 2.33 MeV for up to a 14-..mu..m-diam melanoma cell. Thus, if /sup 10/B can be selectively accumulated in melanoma, it can be destroyed without injury to the surrounding normal tissues by concentrating high linear energy transfer particles. The authors have synthesized seven melanoma-seeking /sup 10/B compounds, two of which, /sup 10/B12-chlorpromazine(/sup 10/B/sup 12/-CPZ) and /sup 10/B/sub 1/-p-boronophenylalanine(/sup 10/B/sub 1/-BPA), are found to be highly effective. The enhanced melanoma-killing effect of the /sup 10/B compounds is found by in vitro radiobiological analysis. A chemical assay and alpha-track analysis 28 h after systemic administration to melanoma-bearing hamsters reveals a /sup 10/B melanoma/blood ratio of 11.5 and a melanoma/liver ratio of 15. Establishment of a clinical therapeutic method for curing human melanoma without failure is underway by correlating biophysical, biochemical, biological, and therapeutic data analysis. Recently, the authors have also been working to develop neutron capture therapy using /sup 10/B-monoclonal antibodies for melanoma and were able to make some /sup 10/B conjugates with the specific m259-0 antibody.

Mishima, Y.; Ichihashi, M.; Hatta, S.

1986-01-01

186

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments  

SciTech Connect

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.

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

187

Spectrum evaluation at the filter-modified neutron irradiation field for neutron capture therapy in Kyoto University Research Reactor  

Microsoft Academic Search

The Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor (KUR-HWNIF) was updated in March 1996, mainly to improve the facility for neutron capture therapy (NCT). In this facility, neutron beams with various energy spectra, from almost pure thermal to epithermal, are available. The evaluation of the neutron energy spectra by multi-activation-foil method was performed as a series

Yoshinori Sakurai; Tooru Kobayashi

2004-01-01

188

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

NASA Astrophysics Data System (ADS)

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 .

Matsuo, Masayuki

2015-03-01

189

Direct estimation of capture cross sections in the presence of slow capture: application to the identification of quenched-in deep-level defects in Ge  

NASA Astrophysics Data System (ADS)

Quenching experiments have been performed on both n- and p-type Ge in a dedicated furnace using infrared lamp heating. The capture and emission characteristics of the induced deep-level defects in the quenched samples were investigated by means of deep level transient spectroscopy. For all defect levels, a high impact of capture in the transition region (slow capture) was found. An empirical approach to analyse this effect is presented, which allows to extract reliable capture cross section parameters. The defect parameters thus obtained were compared with previously published data and it was found that some prominent quenching-induced deep levels are related to metal impurities (Cu and Ni), while others may be vacancy-related.

Segers, S. H.; Lauwaert, J.; Clauws, P.; Simoen, E.; Vanhellemont, J.; Callens, F.; Vrielinck, H.

2014-12-01

190

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

PubMed Central

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.

Farhood, Bagher

2014-01-01

191

Ultrahigh-intensity lead slowing-down neutron spectrometer driven by proton beam of Moscow Meson Factory (MMF)  

SciTech Connect

The construction of the new neutron lead slowing down spectrometer (LNS) and the program of research at this spectrometer is presented. The spectrometer would have the record neutron flux of 10{sup 6} to 10{sup 7} neutrons/cm{sup 2}/s/eV at the sample at the neutron energy of <50 keV. The possibility of creating the slowing down systems for generating intense neutron fluxes with Maxwellian (time-averaged) spectra at temperatures of 10 to 50 keV for direct measurement of the neutron cross-sections, that are necessary for stellar nucleosynthesis calculations, is discussed.

Alekseev, A.A.; Bergman, A.A.; Fedchenko, V.A.; Kazarnovski, M.V.; Langer, O.A.; Matushko, G.K.; Matushko, V.L.; Novoselov, S.A.; Ryabov, Yu.V.; Stavissky, Yu.Ya. [Institut for Nuclear Research RASc, Moscow (Russian Federation)] [and others

1994-12-31

192

Neutron-capture elements in the s- and r-process-rich stars: Constraints on neutron-capture nucleosynthesis processes  

E-print Network

The chemical abundances of the very metal-poor double-enhanced stars are excellent information for setting new constraints on models of neutron-capture processes at low metallicity. These stars are known as s+r stars, since they show enhancements of both s-process and r-process elements. The observed abundance ratios for the double-enhanced stars can be explained by those of stars that were polluted by an AGB star and subsequently accreted very significant amounts of r-process material out of an AIC (accretion-induced collapse) or Type 1.5 supernova. In this paper we present for the first time an attempt to fit the elemental abundances observed in the s- and r-rich, very metal-poor stars using a parametric model and suggest a new concept of component coefficients to describe the contributions of the individual neutron-capture processes to double-enhanced stars. We find that the abundance ratios of these stars are best fitted by enrichments of s- and r-process material. The overlap factor in the AGB stars where the observed s-process elements were produced lies between 0.1 and 0.81. Taking into account the dependence of the initial-final mass relations on metallicity, this wide range of values could possibly be explained by a wide range of core-mass values of AGB stars at low metallicity. The component coefficient of the r-process is strongly correlated with the component coefficient of the s-process for the double-enhanced stars. This is significant evidence that the r-process material in double-enhanced stars comes from an AIC or Type 1.5 supernova.

Bo Zhang; Kun Ma; Guide Zhou

2006-05-14

193

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

PubMed Central

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

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

2015-01-01

194

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

SciTech Connect

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.

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

2008-09-01

195

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

PubMed

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

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

2015-03-01

196

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

SciTech Connect

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.

Ullmann, J.L.; Esch, E.-I.; Haight, R.C.; Hunt, L.; O'Donnell, J.M.; Reifarth, R. [LANSCE Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Agvaanluvsan, U. [Physics Dept., North Carolina State University, Raleigh, NC 27695C (United States); Alpizar, A.; Hatarik, R. [LANSCE Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Physics Department, Colorado School of Mines, Golden, Colorado 80401 (United States); Bond, E.M.; Bredeweg, T.A.; Kronenberg, A.; Rundberg, R.S.; Vieira, D.J.; Wilhelmy, J.B. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Folden, C.M.; Hoffman, D.C. [Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720 (United States); Greife, U. [Physics Department, Colorado School of Mines, Golden, Colorado 80401 (United States); Schwantes, J.M. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720 (United States); Strottman, D.D. [Theory Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)] [and others

2005-05-24

197

Measurement of keV-NEUTRON Capture Cross Sections of I-129  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 129I were measured in the energy region from 15 to 90 keV, using a 1.5-ns pulsed neutron beam and a Time-Of-Flight method. The capture ? rays were detected with a large anti-Compton NaI(Tl) spectrometer, and the capture yields were obtained by a pulse-height weighting technique. Using standard capture cross sections of 197Au, the capture cross sections of 129I were derived with the errors of about 7 %.

Matsumoto, T.; Igashira, M.; Ohsaki, T.

2003-06-01

198

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

PubMed

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

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

1998-09-01

199

Boron neutron capture therapy induces apoptosis of glioma cells through Bcl2\\/Bax  

Microsoft Academic Search

BACKGROUND: Boron neutron capture therapy (BNCT) is an alternative treatment modality for patients with glioma. The aim of this study was to determine whether induction of apoptosis contributes to the main therapeutic efficacy of BNCT and to compare the relative biological effect (RBE) of BNCT, ?-ray and reactor neutron irradiation. METHODS: The neutron beam was obtained from the Xi'an Pulsed

Peng Wang; Haining Zhen; Xinbiao Jiang; Wei Zhang; Xin Cheng; Geng Guo; Xinggang Mao; Xiang Zhang

2010-01-01

200

Accelerator-based epithermal neutron beam design for neutron capture therapy  

SciTech Connect

Recent interest in the production of epithermal neutrons for use in boron neutron capture therapy (BNCT) has prompted an investigation into the feasibility of generating such neutrons with a high current proton accelerator. Energetic protons (2.5 MeV) on a {sup 7}Li target produce a spectrum of neutrons with maximum energy of roughly 800 keV. A number of combinations of D{sub 2}O moderator, lead reflector, {sup 6}Li thermal neutron filtration, and D{sub 2}O/ {sup 6}Li shielding will result in a useful epithermal flux of 1.6{times}10{sup 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{times}19-cm length D{sub 2}O 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.

Yanch, J.C.; Zhou, X. (Department of Nuclear Engineering and Whitaker College of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)); Shefer, R.E.; Klinkowstein, R.E. (Science Research Laboratory, Somerville, Massachusetts 02143 (United States))

1992-05-01

201

Boron neutron capture therapy (BNCT): implications of neutron beam and boron compound characteristics.  

PubMed

The potential efficacy of boron neutron capture therapy (BNCT) for malignant glioma is a significant function of epithermal-neutron beam biophysical characteristics as well as boron compound biodistribution characteristics. Monte Carlo analyses were performed to evaluate the relative significance of these factors on theoretical tumor control using a standard model. The existing, well-characterized epithermal-neutron sources at the Brookhaven Medical Research Reactor (BMRR), the Petten High Flux Reactor (HFR), and the Finnish Research Reactor (FiR-1) were compared. Results for a realistic accelerator design by the E. O. Lawrence Berkeley National Laboratory (LBL) are also compared. Also the characteristics of the compound p-Boronophenylaline Fructose (BPA-F) and a hypothetical next-generation compound were used in a comparison of the BMRR and a hypothetical improved reactor. All components of dose induced by an external epithermal-neutron beam fall off quite rapidly with depth in tissue. Delivery of dose to greater depths is limited by the healthy-tissue tolerance and a reduction in the hydrogen-recoil and incident gamma dose allow for longer irradiation and greater dose at a depth. Dose at depth can also be increased with a beam that has higher neutron energy (without too high a recoil dose) and a more forward peaked angular distribution. Of the existing facilities, the FiR-1 beam has the better quality (lower hydrogen-recoil and incident gamma dose) and a penetrating neutron spectrum and was found to deliver a higher value of Tumor Control Probability (TCP) than other existing beams at shallow depth. The greater forwardness and penetration of the HFR the FiR-1 at greater depths. The hypothetical reactor and accelerator beams outperform at both shallow and greater depths. In all cases, the hypothetical compound provides a significant improvement in efficacy but it is shown that the full benefit of improved compound is not realized until the neutron beam is fully optimized. PMID:10435523

Wheeler, F J; Nigg, D W; Capala, J; Watkins, P R; Vroegindeweij, C; Auterinen, I; Seppälä, T; Bleuel, D

1999-07-01

202

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

NASA Astrophysics Data System (ADS)

Background: We consider the muon capture reaction ?-+2H???+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 (?D). The total capture rate for the muon capture ?-+3He???+3H (?0) is also analyzed, although, in this case, the n n system is not so clean anymore. Purpose: We investigate whether ?D (and ?0) 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 ?D. 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 ? =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 ?D 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 ?0 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 ?D. Finally, a comparison with the already available experimental data discourages the possibility of a bound di-neutron state (positive an n).

Marcucci, L. E.; Machleidt, R.

2014-11-01

203

Neutron dosimetry, moderated energy spectrum, and neutron capture therapy for californium-252 medical sources  

NASA Astrophysics Data System (ADS)

Examination of neutron dosimetry for 252Cf has been conducted using calculative and experimental means. Monte Carlo N-Particle (MCNP) transport code was used in a distributed computing environment as a parallel virtual machine (PVM) to determine the absorbed neutron dose and neutron energy spectrum from 252Cf in a variety of clinically relevant materials. Herein, a Maxwellian spectrum was used to model the 252Cf neutron emissions within these materials. 252Cf mixed-field dosimetry of Applicator Tube (AT) type sources was measured using 1.0 and 0.05 cm3 tissue-equivalent ion chambers and a miniature GM counter. A dosimetry protocol was formulated similar that of ICRU 45. The 252Cf AT neutron dosimetry was determined in the cylindrical coordinate system formalism recommended by the AAPM Task Group 43. These results demonstrated the overwhelming dependence of dosimetry on the source geometry factor as there was no significant neutron attenuation within the source or encapsulation. Gold foils and TLDs were used to measure the thermal flux in the vicinity of 252Cf AT sources to compare with the results calculated using MCNP. As the fast neutron energy spectrum did not markedly changed at increasing distances from the AT source, neutron dosimetry results obtained with paired ion chambers using fixed sensitivity factors agreed well with MCNP results and those in the literature. Calculations of moderated 252Cf neutron energy spectrum with various loadings of 10B and 157Gd were performed, in addition to analysis of neutron capture therapy dosimetry with these isotopes. Radiological concerns such as personnel exposure and shielding of 252Cf emissions were examined. Feasibility of a high specific-activity 252Cf HDR source was investigated through radiochemical and metallurgical studies using stand-ins such as Tb, Gd and 249Cf. Issues such as capsule burst strength due to helium production for a variety of proposed HDR sources were addressed. A recommended 252Cf source strength of at least 1mg was necessary for fabrication of a 252Cf HDR source.

Rivard, Mark Joseph

204

MCNP speed advances for boron neutron capture therapy  

SciTech Connect

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.

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

1998-04-01

205

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

PubMed

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

Barth, Rolf F

2009-07-01

206

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

SciTech Connect

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)

Broekman, J. D. [University of Missouri, Research Reactor Center, 1513 Research Park Drive, Columbia, MO 65211-3400 (United States); Nigg, D. W. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States); Hawthorne, M. F. [University of Missouri, International Institute of Nano and Molecular Medicine, 1514 Research Park Dr., Columbia, MO 65211-3450 (United States)

2013-07-01

207

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

PubMed

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

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

2005-10-28

208

Study on High Speed Lithium Jet For Neutron Source of Boron Neutron Capture Therapy (BNCT)  

NASA Astrophysics Data System (ADS)

The feasibility study of a liquid lithium type proton beam target was performed for the neutron source of the boron neutron capture therapy (BNCT). As the candidates of the liquid lithium target, a thin sheet jet and a thin film flow on a concave wall were chosen, and a lithium flow experiment was conducted to investigate the hydrodynamic stability of the targets. The surfaces of the jets and film flows with a thickness of 0.5 mm and a width of 50 mm were observed by means of photography. It has been found that a stable sheet jet and a stable film flow on a concave wall can be formed up to certain velocities by using a straight nozzle and a curved nozzle with the concave wall, respectively.

Takahashi, Minoru; Kobayashi, Tooru; Zhang, Mingguang; Mák, Michael; Štefanica, Jirí; Dostál, Václav; Zhao, Wei

209

General Electric PETtrace cyclotron as a neutron source for boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

This research investigates the use of a PETtrace cyclotron produced by General Electric (GE) as a neutron source for boron neutron capture therapy (BNCT). The GE PETtrace was chosen for this investigation because this type of cyclotron is popular among nuclear pharmacies and clinics in many countries; it is compact and reliable; it produces protons with energies high enough to produce neutrons with appropriate energy and fluence rate for BNCT and it does not require significant changes in design to provide neutrons. In particular, the standard PETtrace 18O target is considered. The cyclotron efficiency may be significantly increased if unused neutrons produced during radioisotopes production could be utilized for other medical modalities such as BNCT at the same time. The resulting dose from the radiation emitted from the target is evaluated using the Monte Carlo radiation transport code MCNP at several depths in a brain phantom for different scattering geometries. Four different moderating materials of various thicknesses were considered: light water, carbon, heavy water, arid Fluental(TM). The fluence rate tally was used to calculate photon and neutron dose, by applying fluence rate-to-dose conversion factors. Fifteen different geometries were considered and a 30-cm thick heavy water moderator was chosen as the most suitable for BNCT with the GE PETtrace cyclotron. According to the Brookhaven Medical Research Reactor (BMRR) protocol, the maximum dose to the normal brain is set to 12.5 RBEGy, which for the conditions of using a heavy water moderator, assuming a 60 muA beam current, would be reached with a treatment time of 258 min. Results showed that using a PETtrace cyclotron in this configuration provides a therapeutic ratio of about 2.4 for depths up to 4 cm inside a brain phantom. Further increase of beam current proposed by GE should significantly improve the beam quality or the treatment time and allow treating tumors at greater depths.

Bosko, Andrey

210

Fast neutron radiotherapy and boron neutron capture therapy: application to a human melanoma test system.  

PubMed

Fast neutron radiotherapy has proven to be an effective form of treatment in a selected subset of tumors (salivary gland tumors, sarcomas, and locally-advanced prostate cancer), but has not proven to be more beneficial than conventional photon irradiation for the majority of tumor types upon which it has been tested. Normal tissue tolerance limits preclude simply further escalating the neutron dose. Boron neutron capture (BNC) provides a way of selectively augmenting the radiation dose to the tumor. This process is described, and cell culture and animal model data reviewed. An irradiation configuration was developed where an enhancement of 2.10(-3) for 1 microgram of 10B per gram of tissue was achieved. This is similar to the enhancement achievable in the center of a 20 x 20 cm field envisioned for future applications such as metastases in the brain. A boron concentration of 50 micrograms per gram of tumor tissue leads to a 10% increase in the delivered physical dose in this scenario. The first human test of BNC enhancement of a fast neutron radiotherapy beam using pharmacologically-acceptable doses of orally-administered, 10B-enriched, L-paraboronophenylalanine is reported. An enhancement of tumor response was demonstrated for a melanoma skin nodule test system. Boron levels achieved in blood, skin, and tumors are presented. Future research plans are discussed. PMID:8949778

Laramore, G E; Risler, R; Griffin, T W; Wootton, P; Wilbur, D S

1996-01-01

211

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

SciTech Connect

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.

Chyzh, A; Wu, C Y

2011-02-14

212

Neutron Transmission and Capture Measurements and Resonance Parameter Analysis of Neodymium from 1 to 500 eV  

E-print Network

Neutron Transmission and Capture Measurements and Resonance Parameter Analysis of Neodymium from 1 is a 235 U fission product and is important for reactor neutronic calculations. The aim of the present work is to improve upon the existing neutron cross-section data of neodymium. Neutron capture and transmission

Danon, Yaron

213

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

NASA Astrophysics Data System (ADS)

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.

Ullmann, J. L.

2014-09-01

214

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

Microsoft Academic Search

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

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

2009-01-01

215

Stellar (n,?) Cross Sections of Radioactive Nuclei - Tests for Neutron Capture Nucleosynthesis  

NASA Astrophysics Data System (ADS)

Neutron capture nucleosynthesis in Red Giant stars has produced about half of the elemental abundances between Fe and Bi. Models for this scenario can be sensitively tested via characteristic isotope patterns. These are formed by branchings in the reaction path and reflect the physical conditions at the stellar site. The essential nuclear physics input for such studies are the neutron capture cross sections of the involved isotopes including those of the radioactive branch point nuclei. Measurements on this species are difficult due to the limited neutron fluxes available at traditional facilities. In this respect, spallation neutron sources offer a new and promising approach for a variety of experiments on hitherto inaccessible nuclei.

Käppeler, Franz

1998-10-01

216

Monte Carlo Calculations of Selected Dose Components in a Head Model for Boron Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

Boron Neutron Capture Therapy is a very promising form of cancer therapy, consisting in irradiating a stable isotope of boron (10B) concentrated in tumor cells with a low energy neutron beam. This technique makes it possible to destroy tumor cells, leaving healthy tissues practically unaffected. In order to carry out the therapy in the proper way, the proper range of the neutron beam energy has to be chosen. In this paper we present the results of the calculations, using the MCNP code, aiming at studying the energetic dependence of the absorbed dose from the neutron capture reaction on boron (the therapeutic dose), and hydrogen and nitrogen (the injuring dose).

Tymi?ska, Katarzyna

2007-01-01

217

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

PubMed

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

Blue, Thomas E; Yanch, Jacquelyn C

2003-01-01

218

Neutron tomographic fissile assay in spent fuel using the lead slowing down time spectrometer  

NASA Astrophysics Data System (ADS)

A tomographical fissile assay technique for light water reactor spent fuels was developed based on the lead slowing down time spectrometer (LSDTS). The Monte Carlo method was used for system performance and for simulation of the sensitivity of detection of fissile materials using neutron emission tomography. A typical spent PWR fuel element was simulated and the spatial and mass sensitivity of the fissile components were investigated. From these studies, the LSDTS system is shown to be a very sensitive device for analyzing the spatial distribution of total fissile materials of a spent fuel assembly in a properly selected assay neutron energy range. This method is also applicable to nuclear waste assay.

Lee, Yong-Deok; Block, R. C.; Slovacek, R. E.; Harris, D. R.; Abdurrahman, N. M.

2001-02-01

219

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

NASA Astrophysics Data System (ADS)

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.

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

1999-11-01

220

Determination of the parahydrogen fraction in a liquid hydrogen target using energy-dependent slow neutron transmission  

Microsoft Academic Search

The NPDGamma collaboration is performing a measurement of the very small parity-violating asymmetry in the angular distribution of the 2.2MeV ?-rays from the capture of polarized cold neutrons on protons (A?). The estimated size of A? is 5×10?8, and the measured asymmetry is proportional to the neutron polarization upon capture. Since the interaction of polarized neutrons with one of the

L. Barrón-Palos; R. Alarcon; S. Balascuta; C. Blessinger; J. D. Bowman; T. E. Chupp; S. Covrig; C. B. Crawford; M. Dabaghyan; J. Dadras; M. Dawkins; W. Fox; M. T. Gericke; R. C. Gillis; B. Lauss; M. B. Leuschner; B. Lozowski; R. Mahurin; M. Mason; J. Mei; H. Nann; S. I. Penttilä; W. D. Ramsay; A. Salas-Bacci; S. Santra; P.-N. Seo; M. Sharma; T. Smith; W. M. Snow; W. S. Wilburn; V. Yuan

2011-01-01

221

Radiobiological evaluation of new boron delivery agents for boron neutron capture therapy  

E-print Network

This thesis evaluates the radiobiological effectiveness of three new boron compounds namely a boronated porphyrin (BOPP) and two liposome formulations for neutron capture therapy (BNCT). The methodology utilizes in vitro ...

Chung, Yoonsun

2008-01-01

222

Investigation of elemental analysis using neutron-capture gamma ray spectra  

E-print Network

This thesis evaluated the potential of neutron-capture gamma rays in elemental analysis. A large portion of the work was devoted to the development of a method for the analysis of weak peaks in gamma ray spectra. This was ...

Hamawi, John Nicholas

1969-01-01

223

Lambda-Neutron Scattering Lengths from Radiative K-minus Capture  

E-print Network

Radiative capture of the K-minus by the deuteron as a reaction for measurement of the Lambda-neutron scattering lengths. The use of spin information to separate the singlet and triplet scattering lengths is treated.

W. R. Gibbs; S. A. Coon; H. K. Han; B. F. Gibson

2000-01-02

224

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

DOEpatents

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

Gabel, D.

1992-09-01

225

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

DOEpatents

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

Gabel, D.

1991-06-04

226

Development of a gamma ray telescope for online synovial dosimetry in boron neutron capture synovectomy  

E-print Network

Boron Neutron Capture Synovectomy (BNCS) is a novel application of the ¹?B(n,?) reaction for potential treatment of rheumatoid arthritis. During BNCS clinical trials, real-time knowledge of boron dose delivered to the ...

Jiang, Hongyu, 1971-

2003-01-01

227

Exploration of direct neutron capture with covariant density functional theory inputs  

NASA Astrophysics Data System (ADS)

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.

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

2015-04-01

228

Carboranyl Nucleosides & Oligonucleotides for Neutron Capture Therapy Final Report  

SciTech Connect

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.

Schinazi, Raymond F.

2004-12-01

229

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

SciTech Connect

This report describes progress made in refining of neutron-induced alpha tract autoradiography, in designing epithermal neutron bean at MITR-II and in planning treatment dosimetry using Monte Carlo techniques.

Zamenhof, R.G.

1988-01-01

230

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

SciTech Connect

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)

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

1982-01-01

231

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

NASA Astrophysics Data System (ADS)

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.

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

232

Neutron capture measurement on 173Lu at LANSCE with DANCE detector  

NASA Astrophysics Data System (ADS)

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.

Theroine, C.; Ebran, A.; Méot, 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

233

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

SciTech Connect

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.

Theroine, C.; Ebran, A.; Meot, V.; Roig, O. [CEA DAM DIF, F-91297 Arpajon (France); 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. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2013-06-10

234

Measurements of neutron distribution in neutrons-gamma-rays mixed field using imaging plate for neutron capture therapy.  

PubMed

The imaging plate (IP) technique is tried to be used as a handy method to measure the spatial neutron distribution via the (157)Gd(n,gamma)(158)Gd reaction for neutron capture therapy (NCT). For this purpose, IP is set in a water phantom and irradiated in a mixed field of neutrons and gamma-rays. The Hiroshima University Radiobiological Research Accelerator is utilized for this experiment. The neutrons are moderated with 20-cm-thick D(2)O to obtain suitable neutron field for NCT. The signal for IP doped with Gd as a neutron-response enhancer is subtracted with its contribution by gamma-rays, which was estimated using IP without Gd. The gamma-ray response of Gd-doped IP to non-Gd IP is set at 1.34, the value measured for (60)Co gamma-rays, in estimating the gamma-ray contribution to Gd-doped IP signal. Then measured distribution of the (157)Gd(n,gamma)(158)Gd reaction rate agrees within 10% with the calculated value based on the method that has already been validated for its reproducibility of Au activation. However, the evaluated distribution of the (157)Gd(n,gamma)(158)Gd reaction rate is so sensitive to gamma-ray energy, e.g. the discrepancy of the (157)Gd(n,gamma)(158)Gd reaction rate between measurement and calculation becomes 30% for the photon energy change from 33keV to 1.253MeV. PMID:19726204

Tanaka, Kenichi; Endo, Satoru; Hoshi, Masaharu

2010-01-01

235

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

SciTech Connect

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.

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

2005-11-01

236

Monte Carlo calculations of epithermal and fast neutron dose in a human head model for Boron Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

Boron Neutron Capture Therapy is a very promising form of cancer therapy, consisting in irradiating a stable isotope of boron (10B) concentrated in tumor cells with a low energy neutron beam. This technique makes it possible to destroy tumor cells, leaving healthy tissues practically unaffected. In order to carry out the therapy in the proper way, the proper range of the neutron beam energy has to be chosen. In this paper we continue the earlier started calculations of the optimum energy range for BNCT, taking into account the absorbed dose from fast neutrons.

Tyminska, Katarzyna

2008-01-01

237

Analysis of mean lifetime for capture of neutrons in boron-loaded plastic scintillators  

Microsoft Academic Search

The commercial availability of boron-loaded organic scintillators has led to the development of neutron detectors that operate as ``electronically'' black, totally absorbing spectrometers. The key to the enhanced spectroscopy is the delayed capture of nearly thermalized neutrons by 10B that can occur within a few microseconds after the energy pulse from prompt proton recoils. Accurate information regarding the mean lifetime

E. A. Kamykowski

1990-01-01

238

The Ubiquity of the Rapid Neutron-capture Process  

NASA Astrophysics Data System (ADS)

To better characterize the abundance patterns produced by the r-process, we have derived new abundances or upper limits for the heavy elements zinc (Zn, Z= 30), yttrium (Y, Z= 39), lanthanum (La, Z= 57), europium (Eu, Z= 63), and lead (Pb, Z= 82). Our sample of 161 metal-poor stars includes new measurements from 88 high-resolution and high signal-to-noise spectra obtained with the Tull Spectrograph on the 2.7 m Smith Telescope at the McDonald Observatory, and other abundances are adopted from the literature. We use models of the s-process in asymptotic giant branch stars to characterize the high Pb/Eu ratios produced in the s-process at low metallicity, and our new observations then allow us to identify a sample of stars with no detectable s-process material. In these stars, we find no significant increase in the Pb/Eu ratios with increasing metallicity. This suggests that s-process material was not widely dispersed until the overall Galactic metallicity grew considerably, perhaps even as high as [Fe/H] =-1.4, in contrast with earlier studies that suggested a much lower mean metallicity. We identify a dispersion of at least 0.5 dex in [La/Eu] in metal-poor stars with [Eu/Fe] <+0.6 attributable to the r-process, suggesting that there is no unique "pure" r-process elemental ratio among pairs of rare earth elements. We confirm earlier detections of an anti-correlation between Y/Eu and Eu/Fe bookended by stars strongly enriched in the r-process (e.g., CS 22892-052) and those with deficiencies of the heavy elements (e.g., HD 122563). We can reproduce the range of Y/Eu ratios using simulations of high-entropy neutrino winds of core-collapse supernovae that include charged-particle and neutron-capture components of r-process nucleosynthesis. The heavy element abundance patterns in most metal-poor stars do not resemble that of CS 22892-052, but the presence of heavy elements such as Ba in nearly all metal-poor stars without s-process enrichment suggests that the r-process is a common phenomenon. This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

Roederer, Ian U.; Cowan, John J.; Karakas, Amanda I.; Kratz, Karl-Ludwig; Lugaro, Maria; Simmerer, Jennifer; Farouqi, Khalil; Sneden, Christopher

2010-12-01

239

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

SciTech Connect

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.

Katabuchi, Tatsuya; Igashira, Masayuki [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

2012-11-12

240

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

SciTech Connect

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.

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

1995-08-01

241

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

SciTech Connect

The neutron capture cross sections for {sup 207,208}Pb have been measured in the neutron energy region from 10 to 110 keV. The ?-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 ?-ray energy spectra enabled us to determine neutron capture cross sections for {sup 207,208}Pb with small systematic errors, since we could distinguish ?-ray of {sup 207,208}Pb(n,?) reactions from background ?-ray with use of the ?-ray spectra. The obtained cross sections include both contributions of resonance and direct capture components different from the previous TOF measurements.

Segawa, M.; Toh, Y.; Harada, H.; Kitatani, F.; Koizumi, M.; Fukahori, T.; Iwamoto, N.; Iwamoto, O. [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Oshima, M. [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan and Japan Chemical Analysis Center (Japan); Hatsukawa, Y. [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Nagai, Y. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Igashira, M. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152-8550 (Japan); Kamada, S. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152-8550, Japan and National Maritime Research Institute (Japan); Tajika, M. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152-8550, Japan and Hitachi Solutions, Ltd. (Japan)

2014-05-02

242

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

SciTech Connect

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.

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. [CEA/DIF/DPTA Service de Physique Nucleaire, BP 12, F-91680 Bruyeres-le-Chatel (France); CEA/DSM/DAPNIA Service de Physique Nucleaire, CE Saclay, F-91191 Gif-sur-Yvette (France); CEA/DIF/DASE Service de Radioanalyse, Chimie et Environnement, BP 12, F-91680 Bruyeres-le-Chatel (France); CEA-CNRS Laboratoire Pierre Suee, CE Saclay, F-91191 Gif-sur-Yvette (France); CEA/DSM/DAPNIA Service Ingenierie des systemes, CE Saclay, F-91191 Gif-sur-Yvette (France); CEA/DRT/LIST/DETECS/SSTM/LETS, CE Saclay, F-91191 Gif-sur-Yvette (France)

2006-01-15

243

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

NASA Astrophysics Data System (ADS)

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.

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

244

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

SciTech Connect

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.

Alpizar-Vicente, A. M.; Hatarik, R. [Colorado School of Mines, Golden, C0 80401 (United States); Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); 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. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Greife, U. [Colorado School of Mines, Golden, C0 80401 (United States)

2006-03-13

245

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

PubMed

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 Li(2)CO(3) 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. PMID:17327660

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

2007-03-21

246

An Infrared Survey of Neutron-Capture Elements in Planetary Nebulae  

NASA Astrophysics Data System (ADS)

We present results from an ongoing survey of the infrared emission lines [Kr III] 2.199 and [Se IV] 2.287 ? m, first identified by Dinerstein (2001, ApJ, 550, L223), in planetary nebulae (PNe). Isotopes of Se (Z=34) and Kr (Z=36) are created by the slow neutron-capture process (s-process) during the asymptotic giant branch (AGB) phase, and may be brought to the stellar envelope by third dredge-up (TDU). Therefore, PNe will be enriched in n-capture elements if efficient TDU occurred in the progenitor star. Since intermediate-mass stars are the source of a significant fraction of the s-process isotopes in the Galaxy (via TDU), measurement of n-capture element abundances in PNe is of vital importance for models of Galactic chemical evolution. Using CoolSpec (Lester et al. 2000, PASP, 112, 384) on the 2.7-m Harlan J. Smith telescope at McDonald Observatory, we have observed 49 PNe and detected [Kr III] and/or [Se IV] in 27. The high detection rate demonstrates that these two lines are measurable in a significant fraction of Galactic PNe. We use the ionization correction factors Se3+/Se ? Ar++/Ar and Kr++/Kr ? S++/S to derive total elemental abundances, and find that the Kr and Se abundances vary widely among the studied PNe, from roughly solar to overabundant by a factor of 10. This indicates that the efficiency of TDU differed significantly among our sample's progenitor stars. We compare the derived Kr and Se abundances to other nebular properties to search for correlations. Our initial results lend support to the suggestion of Sterling, Dinerstein, & Bowers (2002, ApJ, 578, L55) that n-capture element abundances are larger in PNe with Wolf-Rayet ([W-R]) central stars than those without. This is believed to be due to the heavy mass loss and/or deep mixing which these stars experienced as they evolved into H-poor, C-rich [W-R] stars. This research is supported by NSF grant AST 97-31156.

Sterling, N. C.; Dinerstein, H. L.

2003-12-01

247

Enhanced Particle Capture in Slow Sand Filters using a Filter Aid O b j e c t i v e s  

E-print Network

pump was connected at the bottom end of the filter to regulate the filter approach velocity, which valves Filter Pinch valve Peristaltic pump Pressure sensor #12;Enhanced Particle Capture in Slow Sand

248

Measurement of keV-NEUTRON Capture Cross Section of 209Bi  

NASA Astrophysics Data System (ADS)

The capture cross sections of 209Bi were measured in a neutron energy region from 10 to 100 keV and at 520 keV, using pulsed keV neutrons from the 7Li(p, n)7Be reaction and a time-of-flight method. The capture ? rays from a bismuth or standard gold sample were detected with a large anti-Compton NaI(Tl) spectrometer. The capture yield of the bismuth or gold sample was obtained by applying a pulse-height weighting technique to the corresponding capture ?-ray pulse-height spectrum. The derived capture cross sections from 10 to 100 keV were in good agreement with recent measurements, but that at 520 keV is about half to one third of previous measurements. This large discrepancy was ascribed to the incorrect background-subtraction in the previous measurements.

Saito, K.; Igashira, M.; Kawakami, J.; Ohsaki, T.; Obara, T.; Sekimoto, H.

2003-06-01

249

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

SciTech Connect

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.

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

250

U-238 neutron-capture gamma-cascade generation and transport simulation for capture-tank response (final report). Doctoral thesis  

SciTech Connect

A computer analysis has been performed to evaluate the energy dependent response of a capture tank to the gamma rays emitted in the cascades of the excited U-239 nucleus. This model determines the energies of the gamma-ray cascades, the order of emission of the gamma rays in a cascade, and the gamma-ray multiplicity of the cascades using Monte Carlo techniques. A capture tank responds to the combined effect of the various gamma rays emitted in the cascade. Examined is the energy deposition in a capture tank by the cascades generated in resonant (surface) capture and off-resonant (volumetric) capture, with and without internal conversion. Off-resonant capture deposits, on the average, less energy than resonant capture, due to self-shielding of the gamma-rays in the capture sample. Internal conversion has negligible effect on the average cascade energy deposited in the capture tank. Gamma-ray cascade, Capture tank, U-238 neutron capture.

Rosener, T.J.

1992-05-07

251

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

SciTech Connect

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

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

2008-02-08

252

Uranium Neutron Capture Gamma Cascade Generation and Transport Simulation for Capture Tank Response  

NASA Astrophysics Data System (ADS)

A computer analysis has been performed to evaluate the energy dependent response of a capture tank to the gamma-ray cascades emitted from excited ^ {239}U. The GAMINT code was developed to simulate the decay of the ^{239 }U nucleus, formed in the ^{238}U(n,gamma)^{239 }U reaction, in order to provide the source spectrum for the complete analysis of the capture tank efficiency. This model determines the energies of the gamma-ray cascades, the order of emission of the gamma rays in a cascade, and the gamma-ray multiplicities by Monte Carlo techniques. A gamma-ray emission spectrum for the excited ^{239}U nucleus is generated. In the GAMINT code, known level data for ^{239}U is used below 1 MeV. A statistical approach based on the back-shifted Fermi gas model is used for the continuum level density. A single -particle model description for transition rates, with hindrance factors applied, is used to determine the gamma ray transition probabilities. Internal conversion probabilities are determined and the inclusion of this competing process suppresses the low energy portion of the gamma spectrum. A capture tank responds to the combined effect of the gamma rays of various energies from a cascade, after being transported through the material between the sample and the capture tank. Examined is the energy deposition, in a capture tank, by the cascades generated from resonant and off-resonant capture in a ^{238 }U sample. Internal conversion has a negligible effect on the average cascade energy deposited in the tank. Off -resonant (volumetric) capture deposits, on the average, less energy than resonant (surface) capture in the capture tank as a result of self-shielding of the gamma rays in the capture sample.

Rosener, Thomas Jay

1992-01-01

253

Scattering length measurements from radiative pion capture and neutron-deuteron breakup  

SciTech Connect

The neutron-neutron and neutron-proton {sup 1}S{sub 0} scattering lengths a{sub nn} and a{sub np}, respectively, were determined simultaneously from the neutron-deuteron breakup reaction. Their comparison with the recommended values obtained from two body reactions gives a measure of the importance of three-nucleon force effects in the three-nucleon continuum. In order to check on the result obtained for a{sub nn} from the two-body {pi}{sup {minus}}-d capture reaction, a new measurement was performed at LANL. Preliminary results of the three experiments are given.

Gibson, B.F. [Los Alamos National Lab., NM (United States); Tornow, W. [Duke Univ., Durham, NC (United States). Dept. of Physics]|[Triangle Universities Nuclear Lab., Durham, NC (United States); Carman, T.S. [Lawrence Livermore National Lab., CA (United States)] [and others

1997-07-01

254

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

PubMed

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

Rasouli, Fatemeh S; Masoudi, S Farhad

2015-02-01

255

A Cloud-Chamber Study of the Disintegration of Lithium by Slow Neutrons  

Microsoft Academic Search

The ranges of tritons and alpha-particles formed in the slow neutron reaction 6Li(n,alpha)3H have been measured in a cloud chamber and found to be Ralpha=10.4+\\/-0.2 mm and R3H=60.0+\\/-0.6 mm in air at N.T.P.; the corresponding Q values, derived from the blue-printed Cornell energy vs. range curves, disagree, and the Q derived by the proton relation is also in disaccordance with

J. K. Bøggild; L. Minnhagen

1949-01-01

256

Chandra Captures Neutron Star Action - Duration: 1:01.  

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...

257

The Remodeling and Basic Characteristics of the Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor, Mainly for Neutron Capture Therapy  

Microsoft Academic Search

The Heavy Water Thermal Neutron Facility of the Kyoto University Research Reactor (KUR) was wholly updated in March 1996 mainly for neutron capture therapy. The performance as a neutron irradiation facility was improved using the epithermal neutron moderator of the aluminum-heavy water mixture (Al\\/DâO = 80\\/20 vol%), the neutron energy spectrum shifter of heavy water, and the thermal neutron filters

Tooru Kobayashi; Yoshinori Sakurai; Keiji Kanda; Yoshiaki Fujita; Koji Ono

2000-01-01

258

Neutron-capture elements in the metal-poor globular cluster M15  

E-print Network

We report on observations of six giants in the globular cluster M15 (NGC 7078) using the Subaru Telescope to measure neutron-capture elemental abundances. Our abundance analyses based on high-quality blue spectra confirm the star-to-star scatter in the abundances of heavy neutron-capture elements (e.g., Eu), and no significant s-process contribution to them, as was found in previous studies. We have found, for the first time, that there are anti-correlations between the abundance ratios of light to heavy neutron-capture elements ([Y/Eu] and [Zr/Eu]) and heavy ones (e.g., Eu). This indicates that light neutron-capture elements in these stars cannot be explained by only a single r-process. Another process that has significantly contributed to the light neutron-capture elements is required to have occurred in M15. Our results suggest a complicated enrichment history for M15 and its progenitor.

Kaori Otsuki; Satoshi Honda; Wako Aoki; Toshitaka Kajino; Grant J. Mathews

2006-03-13

259

Neutron transmission and capture cross section measurements for 241Am at the GELINA facility  

NASA Astrophysics Data System (ADS)

Resonance parameters for neutron-induced reactions on 241Am below 110 eV have been determined. The parameters result from a resonance shape analysis of transmission and capture data measured at the time-of-flight facility GELINA, with the accelerator operating at a 50 Hz repetition rate. The transmission experiments were carried out at a 25 m station using a Li glass scintillator. The capture experiments were performed at a 12.5 m station by applying the total energy detection principle in combination with the pulse height weighting technique using a pair of C6D6 detectors. The normalization of the capture data was determined by a combined least squares adjustment of the transmission and capture data. From the adjusted resonance parameters a capture cross section of 749 ± 35 b for a neutron energy of 0.0253 eV and an average radiation width of < ? ? > = 42.0 meV for s-wave resonances were obtained. A missing-level analysis for s-wave neutron resonances within the statistical model results in compatible values with previous estimates. The neutron widths obtained in this work are approximately 22% larger compared to other experimental data and evaluated data libraries. Also the thermal capture cross section is larger than most of the recommended values. However, the resonance parameter file presented in this work is consistent with results of both integral experiments and of the experimentally determined resonance integrals.

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

2013-08-01

260

Current status of boron neutron capture therapy of high grade gliomas and recurrent head and neck cancer  

E-print Network

Boron neutron capture therapy (BNCT) is a biochemically targeted radiotherapy based on the nuclear capture and fission reactions that occur when non-radioactive boron-10, which is a constituent of natural elemental boron, ...

Barth, Rolf F

261

Comparative modelling of performance limits of solid-state neutron detectors based on planar B-rich capture layers  

Microsoft Academic Search

Solid-state neutron detectors based only on boron-rich semiconductors are of interest for their potential to provide the highest thermal neutron detection efficiencies of any solid-state neutron detectors. A simple physical model, recently shown to generate thermal neutron capture product spectra that agree quantitatively with full-physics GEANT4 simulation, is used to compare the capture product energy spectra and the upper limits

A. D. Harken; B. W. Robertson

2006-01-01

262

Review of measurement techniques for the neutron radiative-capture process  

SciTech Connect

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.

Poenitz, W.P.

1981-07-01

263

A neutron resonance capture analysis experimental station at the ISIS spallation source.  

PubMed

Neutron resonance capture analysis (NRCA) is a nuclear technique that is used to determine the elemental composition of materials and artifacts (e.g., bronze objects) of archaeological interest. NRCA experiments are mostly performed at the GELINA facility in Belgium, a pulsed neutron source operating with an electron linear accelerator. Very intense fluxes of epithermal neutrons are also provided by spallation neutron sources, such as the ISIS spallation neutron source in the United Kingdom. In the present study, the suitability of the Italian Neutron Experimental Station (INES) beam line for NRCA measurements is assessed using a compact (n, ?) resonance detector made of a Yttrium-Aluminum-Perovskite (YAP) scintillation crystal coupled with a silicon photomultiplier (SiPM) readout. The measurements provided a qualitative recognition of the composition of the standard sample, a lower limit for the sensitivity for NRCA for almost-in-traces elements, and an estimation of the relative isotopic concentration in the sample. PMID:20828445

Pietropaolo, Antonino; Gorini, Giuseppe; Festa, Giulia; Reali, Enzo; Grazzi, Francesco; Schooneveld, Erik M

2010-09-01

264

Neutron capture therapy: a comparison between dose enhancement of various agents, nanoparticles and chemotherapy drugs.  

PubMed

The aim of this study is to compare dose enhancement of various agents, nanoparticles and chemotherapy drugs for neutron capture therapy. A (252)Cf source was simulated to obtain its dosimetric parameters, including air kerma strength, dose rate constant, radial dose function and total dose rates. These results were compared with previously published data. Using (252)Cf as a neutron source, the in-tumour dose enhancements in the presence of atomic (10)B, (157)Gd and (33)S agents; (10)B, (157)Gd, (33)S nanoparticles; and Bortezomib and Amifostine chemotherapy drugs were calculated and compared in neutron capture therapy. Monte Carlo code MCNPX was used for simulation of the (252)Cf source, a soft tissue phantom, and a tumour containing each capture agent. Dose enhancement for 100, 200 and 500 ppm of the mentioned media was calculated. Calculated dosimetric parameters of the (252)Cf source were in agreement with previously published values. In comparison to other agents, maximum dose enhancement factor was obtained for 500 ppm of atomic (10)B agent and (10)B nanoparticles, equal to 1.06 and 1.08, respectively. Additionally, Bortezomib showed a considerable dose enhancement level. From a dose enhancement point of view, media containing (10)B are the best agents in neutron capture therapy. Bortezomib is a chemotherapy drug containing boron and can be proposed as an agent in boron neutron capture therapy. However, it should be noted that other physical, chemical and medical criteria should be considered in comparing the mentioned agents before their clinical use in neutron capture therapy. PMID:24961208

Khosroabadi, Mohsen; Ghorbani, Mahdi; Rahmani, Faezeh; Knaup, Courtney

2014-09-01

265

Neutron capture cross sections of 194Hg and the decays of 195Hg.  

PubMed

The thermal cross section and resonance integral have been determined for radiative neutron capture by radioactive (194)Hg by observing the ? rays emitted in the decay of (195)Hg. Captures leading to the low-spin isomer of (195)Hg give ?=877 b and I=10,270 b, while captures leading to the high-spin isomer give ?=49 b and I=608 b. Energies and intensities of the ? rays emitted in the decays of (195)Hg produced by neutron capture have been obtained with increased precision relative to previous studies with sources produced by other reactions, leading to correspondingly improved values for ?-decay branching intensities and energy levels in (195)Au. New values for the half-lives of (195g)Hg and (195m)Hg are also reported. PMID:25479438

Dorsett, S F; Krane, K S

2015-02-01

266

Measurement of neutron capture and fission cross sections of 233U in the resonance region  

NASA Astrophysics Data System (ADS)

In the framework of studies concerning new fuel cycles and nuclear wastes incineration experimental data of the ? ratio between capture and fission cross sections of 233U reactions play an important role in the Th/U cycle. The safety evaluation and the detailed performance assessment for the generation IV nuclear-energy system based on 232Th cycle strongly depend on this ratio. Since the current data are scarce and sometimes contradictory, new experimental studies are required. The measurement will take place at the neutron time-of-flight facility GELINA at Geel, designed to perform neutron cross section measurements with high incident neutron-energy resolution. A dedicated high efficiency fission ionization chamber (IC) as fission fragment detector and six C6D6 liquid scintilators sensitive to ?-rays and neutrons will be used. The method, based on the IC energy response study, allowing to distinguish between gammas originating from fission and capture, in the resonance region, will be presented.

Companis, I.; Aïche, M.; Mathieu, L.; Kessedjian, G.; Schillebeeckx, P.; Barreau, G.; Boutoux, G.; Czajkowski, S.; Haas, B.; Jurado, B.; Plompen, A. J. M.; Simutkin, V.; Tsekhanovich, I.

2012-02-01

267

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

NASA Technical Reports Server (NTRS)

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.

Lugmair, G. W.; Marti, K.

1971-01-01

268

Central nervous system tolerance to boron neutron capture therapy with p-boronophenylalanine.  

PubMed Central

A rat spinal cord model was used to evaluate the effects of boron neutron capture irradiation on the central nervous system (CNS), using a range of doses of the boron delivery agent p-boronophenylalanine (BPA). Three doses of BPA 700, 1000 and 1600 mg kg(-1) were used to establish the biodistribution of boron-10 (10B) in blood, spinal cord and brain over a 3-h period after intraperitoneal (i.p.) administration. At the lowest dose of BPA used, blood 10B levels remained relatively stable over the 3-h sampling period. With the two higher doses of BPA, blood 10B concentrations were greatest at 1 h after BPA administration, and thereafter exhibited a biphasic clearance profile. The largest decline in blood 10B levels occurred between 1 and 2 h after i.p. injection and was most pronounced (approximately 45%) in the highest BPA dose group. Considered overall, 10B concentrations were marginally lower in the spinal cord than in the brain. Levels of 10B in both of these organs showed a slow but progressive increase with time after administration of BPA. The 10B concentration ratio for blood relative to CNS tissue increased with BPA dosage and reached a peak value of approximately 10:1 in the highest BPA dose group, at 1 h after i.p. injection. However, at 3 h after injection the 10B concentration ratios had decreased to approximately 3:1 in all of the BPA dose groups. After irradiation with thermal neutrons in combination with BPA at blood 10B concentrations of approximately 42 and approximately 93 microg g(-1), myelopathy developed after latent intervals of 20.0 +/- 0.6 and 20.0 +/- 1.2 weeks respectively. ED50 values (+/- s.e.) for the incidence of myelopathy were calculated from probit-fitted curves, and were 17.5 +/- 0.7 and 25.0 +/- 0.6 Gy after irradiation with thermal neutrons at blood 10B levels of approximately 42 and approximately 93 microg g(-1) respectively. The compound biological effectiveness (CBE) factor values, estimated from these data, were 0.67 +/- 0.23 and 0.48 +/- 0.18 respectively. This compared with a previous estimate of 0.88 +/- 0.14 at a blood 10B concentration of approximately 19 microg g(-1). It was concluded that the value of the CBE factor was not influenced by the level of 10B in the blood, but by the blood:CNS 10B concentration ratio. In effect, the CBE factor decreases as the concentration ratio increases. Simulations using boron neutron capture therapy (BNCT) treatment planning software indicate a significant therapeutic advantage could be obtained in moving to higher BPA doses than those in current clinical use. PMID:9413952

Morris, G. M.; Coderre, J. A.; Micca, P. L.; Fisher, C. D.; Capala, J.; Hopewell, J. W.

1997-01-01

269

33S for Neutron Capture Therapy: Nuclear Data for Monte Carlo Calculations  

NASA Astrophysics Data System (ADS)

A study of the nuclear data required for the Monte Carlo simulation of boron neutron capture therapy including the 33S isotope as an enhancer of the dose at small depths has been performed. In particular, the controversy on the available data for the 33S(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.

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

2014-06-01

270

Neutron capture on 130Sn during r-process freeze-out  

NASA Astrophysics Data System (ADS)

We examine the role of neutron capture on 130Sn 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 130Sn. The changes to the abundance pattern include not only a relative decrease in the abundance of 130Sn and an increase in the abundance of 131Sn, but also a shift in the distribution of material in the rare earth and third peak regions.

Beun, J.; Blackmon, J. C.; Hix, W. R.; McLaughlin, G. C.; Smith, M. S.; Surman, R.

2009-02-01

271

Gamma-ray cascade transitions in ^112Cd and ^114Cd following capture of epithermal neutrons  

NASA Astrophysics Data System (ADS)

Investigation of the properties of the ?-ray transitions in the cadmium isotopes are of importance for nuclear structure and applied physics due to the high cross section for capture of thermal neutrons by ^111Cd and ^113Cd. We report results from a neutron-capture experiment on ^natCd carried out at LANL's LANSCE using the 4? BaF2 DANCE array. Isolated resonances with known spins were selected to study the ?-ray cascade transitions in ^112Cd and ^114Cd. Experimental results are compared with predictions from the code DICEBOX to determine the optimal ?-ray strength function that reproduces these cascade transitions.

Rusev, G.; Jandel, M.; Bredeweg, T. A.; Taddeucci, T. N.; Ullmann, J. L.; Krticka, M.

2012-10-01

272

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

SciTech Connect

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.

Beun, Joshua [North Carolina State University; Blackmon, Jeffery C [Louisiana State University; Hix, William Raphael [ORNL; Mclaughlin, Gail C [North Carolina State University; Smith, Michael Scott [ORNL; Surman, Rebecca [Union College

2009-01-01

273

Development and characteristics of the HANARO neutron irradiation facility for applications in the boron neutron capture therapy field  

NASA Astrophysics Data System (ADS)

The HANARO neutron irradiation facility for various applications in the boron neutron capture therapy (BNCT) field was developed, and its characteristics were investigated. In order to obtain the sufficient thermal neutron flux with a low level of contamination by fast neutrons and gamma rays, a radiation filtering method was adopted. The radiation filter was designed by using a silicon single crystal, cooled by liquid nitrogen, and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room was finished. Neutron beam characteristics were measured by using bare and cadmium-covered gold foils and wires. The in-phantom neutron flux distribution was measured for flux mapping inside the phantom. The gamma-ray dose was determined by using TLD-700 thermoluminescence dosimeters. The thermal and fast neutron fluxes and the gamma-ray dose were calculated by using the MCNP code, and they were compared with experimental data. The thermal neutron flux and Cd ratio available at this facility were confirmed to be 1.49 × 109 n cm-2 s-1 and 152, respectively. The maximum neutron flux inside the phantom was measured to be 2.79 × 109 n cm-2 s-1 at a depth of 3 mm in the phantom. The two-dimensional in-phantom neutron flux distribution was determined, and significant neutron irradiation was observed within 20 mm from the phantom surface. The gamma-ray dose rate for the free beam condition was expected to be about 80 cGy h-1. These experimental results were reasonably well supported by calculation using the facility design code. This HANARO thermal neutron facility can be used not only for clinical trials, but also for various pre-clinical studies in the BNCT field.

Kim, Myong-Seop; Lee, Byung-Chul; Hwang, Sung-Yul; Kim, Heonil; Jun, Byung-Jin

2007-05-01

274

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

Microsoft Academic Search

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.

Zamenhof

1990-01-01

275

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

SciTech Connect

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.

Zamenhof, R.G.

1989-01-01

276

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

SciTech Connect

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.

Ackermann, A.L. (ed.); Dorn, R.V. III.

1990-08-01

277

Boron Neutron Capture Therapy of Cancer: Current Status and Future Prospects  

Microsoft Academic Search

Background: Boron neutron capture therapy (BNCT) isbased on the nuclear reaction that occurswhen boron-10 isirradiated with low-energy thermal neutronsto yield high linear energy transferA particles and recoiling lithium-7 nuclei. Clinical interest in BNCT hasfocused primarily on the treatment of high-grade gliomas and either cutaneous primaries or cerebral metastases of mel- anoma, most recently, head and neck and liver cancer. Neutron

Rolf F. Barth; Jeffrey A. Coderre; M. GraaH

2005-01-01

278

Feasibility of a boron loaded scintillation detector for dose measurements related to boron neutron capture therapy  

Microsoft Academic Search

The feasibility of the use of a boron loaded scintillation detector in a head phantom for boron neutron capture therapy dose estimates was evaluated. Several monoenergetic neutron groups were produced via the ^7Li(p,n)^7Be reaction in a metallic lithium target using the Van de Graaff accelerator at University of Massachusetts Lowell. The pulse-height spectra were taken from a natural boron loaded

Don-Soo Kim; James J. Egan; Gunter H. R. Kegel; David Desimone

2002-01-01

279

A low cost neutron capture prompt gamma-ray analysis facility at a research reactor  

Microsoft Academic Search

A low cost neutron capture prompt gamma activation analysis facility has been constructed at The University of Michigan's\\u000a Pheonix Memorial Laboratory. Although the neutron beam used has a fairly large epithermal component (Cd ratio 7.1), background\\u000a levels are low enough to result in satisfactory measurement of over 16 different elements. For the elements of greatest sensitivity\\u000a (samarium, boron, gadolinium, and

J. D. Jones; M. A. Ludington; W. L. Rigot

1982-01-01

280

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

SciTech Connect

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.

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

1989-08-15

281

Systematic study of neutron capture including the compound, pre-equilibrium, and direct mechanisms  

NASA Astrophysics Data System (ADS)

The neutron capture reaction is investigated. The three major reaction mechanisms, namely, compound-nucleus capture (CNC), pre-equilibrium capture (PEC), and direct capture (DIC), are considered on the basis of the Hauser-Feshbach model, the exciton model, and potential model, respectively. The three mechanisms are treated simultaneously and consistently, i.e, they are obtained on the basis of the same nuclear ingredients, such as the optical potential and nuclear-level densities. In this framework, the three components are calculated on the same footing and represent partial fluxes of the same total reaction cross section. The total neutron-capture cross sections and astrophysical reaction rates are calculated within the updated modern reaction code talys for about 8000 nuclei with 8?Z?110 lying between the proton and neutron drip lines. The nuclear-structure ingredients involved in the calculation are determined from experimental data whenever available and, if not, from global microscopic nuclear models. For the targets with mass number A >26, a fair agreement between the computed total-capture cross sections and experimental data is found but, for the lightest nuclei, only the predicted DIC cross sections reproduce the experimental results satisfactorily. Significant and even dominant contribution to the total reaction rate comes from the DIC component for neutron-rich nuclei, especially in the Z =50-70 region. The impact of the newly determined reaction rates on the r process abundances resulting from the ejection of matter in neutrino-driven winds or the decompression of neutron star matter is investigated.

Xu, Y.; Goriely, S.; Koning, A. J.; Hilaire, S.

2014-08-01

282

On the capture of dark matter by neutron stars  

E-print Network

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 sections based on the observation of old neutron stars with strong dark matter self-interactions. We show that for a dark matter density of $~10^3$ GeV/cm$^3$ and dark matter mass $m_\\chi$ less than approximately 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 $m_\\chi\\sim 10$ GeV when the dark matter interaction cross section with the nucleons ranges from $\\sigma_{\\chi n}\\sim 10^{-52}$ cm$^2$ to $10^{-57}$ cm$^2$, the dark matter self-interaction cross section limit is $\\sigma_{\\chi\\chi}< 10^{-33}$ cm$^2$, which is about ten orders of magnitude stronger than the Bullet Cluster limit.

Tolga Guver; Arif Emre Erkoca; Mary Hall Reno; Ina Sarcevic

2014-04-09

283

Gadolinium neutron capture brachytherapy (GdNCB), a new treatment method for intravascular brachytherapy  

SciTech Connect

Restenosis is a major problem after balloon angioplasty and stent implantation. The aim of this study is to introduce gadolinium neutron capture brachytherapy (GdNCB) as a suitable modality for treatment of stenosis. The utility of GdNCB in intravascular brachytherapy (IVBT) of stent stenosis is investigated by using the GEANT4 and MCNP4B Monte Carlo radiation transport codes. To study capture rate, Kerma, absorbed dose and absorbed dose rate around a Gd-containing stent activated with neutrons, a 30 mm long, 5 mm diameter gadolinium foil is chosen. The input data is a neutron spectrum used for clinical neutron capture therapy in Studsvik, Sweden. Thermal neutron capture in gadolinium yields a spectrum of high-energy gamma photons, which due to the build-up effect gives an almost flat dose delivery pattern to the first 4 mm around the stent. The absorbed dose rate is 1.33 Gy/min, 0.25 mm from the stent surface while the dose to normal tissue is in order of 0.22 Gy/min, i.e., a factor of 6 lower. To spare normal tissue further fractionation of the dose is also possible. The capture rate is relatively high at both ends of the foil. The dose distribution from gamma and charge particle radiation at the edges and inside the stent contributes to a nonuniform dose distribution. This will lead to higher doses to the surrounding tissue and may prevent stent edge and in-stent restenosis. The position of the stent can be verified and corrected by the treatment plan prior to activation. Activation of the stent by an external neutron field can be performed days after catherization when the target cells start to proliferate and can be expected to be more radiation sensitive. Another advantage of the nonradioactive gadolinium stent is the possibility to avoid radiation hazard to personnel.

Enger, Shirin A.; Rezaei, Arash; Munck af Rosenschoeld, Per; Lundqvist, Hans [Division of Biomedical Radiation Sciences, Department of Oncology, Radiology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala (Sweden); Division of Medical Radiation Physics, Department of Oncology-Pathology, Karolinska Institutet, SE-171 76 Stockholm (Sweden) and Studsvik Medical AB, SE-612 82 Nykoeping (Sweden); Department of Radiation Physics, Lund University Hospital, SE-22185 Lund (Sweden); Division of Biomedical Radiation Sciences, Department of Oncology, Radiology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala (Sweden)

2006-01-15

284

Monte Carlo calculations of lung dose in ORNL phantom for boron neutron capture therapy.  

PubMed

Monte Carlo simulations were performed to evaluate dose for possible treatment of cancers by boron neutron capture therapy (BNCT). The computational model of male Oak Ridge National Laboratory (ORNL) phantom was used to simulate tumours in the lung. Calculations have been performed by means of the MCNP5/X code. In this simulation, two opposite neutron beams were considered, in order to obtain uniform neutron flux distribution inside the lung. The obtained results indicate that the lung cancer could be treated by BNCT under the assumptions of calculations. PMID:24435912

Krstic, D; Markovic, V M; Jovanovic, Z; Milenkovic, B; Nikezic, D; Atanackovic, J

2014-10-01

285

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

SciTech Connect

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.

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

2002-08-18

286

Independent Measurement of Theta13 via Neutron Capture on Hydrogen at Daya Bay  

E-print Network

A new measurement of the $\\theta_{13}$ 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 $\\theta_{13}$ measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GW$_{th}$ reactors, the rate deficit observed at the far hall is interpreted as $\\sin^22\\theta_{13}=0.083\\pm0.018$ in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain $\\sin^22\\theta_{13}=0.089\\pm0.008$ as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.

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

2014-07-24

287

Final Report for the “WSU Neutron Capture Therapy Facility Support”  

SciTech Connect

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.

Gerald E. Tripard; Keith G. Fox

2006-08-24

288

Cell survival measurements in an argon, aluminium and sulphur filtered neutron beam: a comparison with 24 keV neutrons and relevance to boron neutron capture therapy.  

PubMed

Boron neutron capture therapy (BNCT) has been advanced as a suitable alternative therapy for the treatment of glioma. BNCT involves the selective uptake of a tumour with a boron-bearing substance and subsequent irradiation with a beam of neutrons. Previous attempts with BNCT have utilized thermal neutrons, but this involves resection of the scalp prior to treatment and is only possible with superficial tumours. An alternative is to use a beam of intermediate-energy neutrons which will produce a peak in the thermal neutron fluence at depth in tissue and so enable deep-seated tumours to be treated. A neutron beam with a mean energy of approximately 9 keV, obtained by filtering neutrons from a reactor with aluminium, argon and sulphur, has been used to explore the radiobiological advantage over thermal and 24 keV neutrons for BNCT. Irradiation of V79 and HeLa cells at various positions in a polythene phantom suggest that the beam is less cytotoxic for a given neutron fluence than the 24 keV neutron beam previously considered as an alternative to thermal neutrons for BNCT. However, optimization of boron distribution via the development of new compounds still appears to be necessary for BNCT to become a safe alternative option for the treatment of glioma. PMID:8000825

Mill, A J; Morgan, G R; Newman, S M

1994-10-01

289

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

SciTech Connect

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%.

Hatarik, R.; Cizewski, J. A.; Hatarik, A. M.; O'Malley, P. D. [Rutgers University, New Brunswick NJ 08903 (United States); Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Lesher, S. R. [Lawrence Livermore National Laboratory, Livermore CA 94550 (United States); Gibelin, J.; Phair, L. [Lawrence Berkeley National Laboratory, Berkeley CA 94720 (United States); Swan, T. [Rutgers University, New Brunswick NJ 08903 (United States); University of Surrey, Guildford GU2 7XH, Surrey (United Kingdom)

2009-03-10

290

Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Niobium  

E-print Network

Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Niobium N. J section of niobium ~1.15 b! prevented a thermal measurement with acceptable accuracy. The KAPL-RPI data that was analyzed consisted of measurements of six different niobium metal samples. The purity of all the samples

Danon, Yaron

291

LOW ENERGY $gamma$ RAYS EMITTED DURING THE CAPTURE OF THERMAL NEUTRONS BY As⁷⁵  

Microsoft Academic Search

The gamma rays emitted during the capture of thermal neutrons by As\\/; sup 75\\/ were studied with a scintillation spectrometer in the low-energy range. ; Energies of 450 plus or minus 10, 403 plus or minus 13, 311 plus or minus ; 8, 249 plus or minus 8, 205 plus or minus 4, and 172 plus or minus 4 ;

M. Cristu; V. Cojocaru; D. Dorcioman; D. Dragomirescu

1960-01-01

292

0-350 KEV GAMMA RAYS FROM THERMAL NEUTRON CAPTURE IN S, Sc, AND I  

Microsoft Academic Search

The level schemes of odd-odd nuclei were determined by using the energy ; and intensity measurements of gamma rays emitted after neutron capture. Gamma ; spectra from Sc⁴⁶ and I¹²⁸ and from S in natural isotopic mixture ; were recorded by a scintillation spectrometer in the region from 0 to 350 kev. ; The apparatus and methods used are described.

M. Cristu; D. Dorcioman; V. Cojocaru; D. Dragomirescu

1961-01-01

293

Monte Carlo simulation of the scattered component of neutron capture prompt gamma-ray analyzer responses  

Microsoft Academic Search

This paper describes a major part of our efforts to simulate the entire spectral response of the neutron capture prompt gamma-ray analyzer for bulk media (or conveyor belt) samples by the Monte Carlo method. This would allow one to use such a model to augment or, in most cases, essentially replace experiments in the calibration and optimum design of these

Y. Jin; K. Verghese; R. P. Gardner

1986-01-01

294

Neutron capture by heavy isotopes of uranium and neptunium under thermonuclear explosion conditions  

Microsoft Academic Search

model. Comparison with experiment has been carried out by means of the p- # diagram which is explained later; this enables us to obtain, for certain approximations, information about the behavior of the radiative neutron capture cross sections of the starting materials from the experimental values of the relative yields of heavy isotopes of the transuranic elements. This comparison shows

V. G. Zagrafov; V. P. Zommer

1967-01-01

295

Spermidinium closo-dodecaborate-encapsulating liposomes as efficient boron delivery vehicles for neutron capture therapy.  

PubMed

closo-Dodecaborate-encapsulating liposomes were developed as boron delivery vehicles for neutron capture therapy. The use of spermidinium as a counter cation of closo-dodecaborates was essential not only for the preparation of high boron content liposome solutions but also for efficient boron delivery to tumors. PMID:25182569

Tachikawa, Shoji; Miyoshi, Tatsuro; Koganei, Hayato; El-Zaria, Mohamed E; Viñas, Clara; Suzuki, Minoru; Ono, Koji; Nakamura, Hiroyuki

2014-10-21

296

Stellar Neutron Capture Cross Sections of the Lu and Hf Isotopes  

SciTech Connect

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.

Wisshak, K.; Voss, F.; Kaeppeler, F. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Kazakov, L. [Institute for Physics and Power Engineering, Obninsk (Russian Federation); Krticka, M. [Faculty of Mathematics and Physics, Charles University, CZ-180 00 Prague (Czech Republic)

2005-05-24

297

Neutron Capture and Total Cross-Section Measurements and Resonance Parameters of Gadolinium  

E-print Network

Neutron Capture and Total Cross-Section Measurements and Resonance Parameters of Gadolinium G to the understanding of gadolinium cross sections is presented, particularly above 180 eV where the ENDF resolved sections of gadolinium accurately. Gado- linium has the highest thermal cross section of any nat- ural

Danon, Yaron

298

Neutron-capture Cross Sections from Indirect Measurements  

SciTech Connect

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.

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

2011-10-18

299

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

NASA Astrophysics Data System (ADS)

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.

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

300

Reaction rate for two-neutron capture by 4 He  

Microsoft Academic Search

Recent investigations suggest that the neutrino-heated hot bubble between the nascent neutron star and the overlying stellar\\u000a mantle of a type-II supernova may be the site of the r-process. In the preceding ?-process building up the elements toA?100, the4He(2n,?)6He- and6He(?,n)9Be-reactions bridging the instability gap atA=5 andA=8 could be of relevance. We suggest a mechanism for4He(2n,?)6He and calculate the reaction rate

V. D. Efros; W. Balogh; H. Herndl; R. Hofinger; H. Oberhummer

1996-01-01

301

Thermal-neutron capture by {sup 58}Ni, {sup 59}Ni, and {sup 60}Ni  

SciTech Connect

We have studied the primary and secondary {gamma} rays (414 in {sup 59}Ni, 390 in {sup 60}Ni, and 240 in {sup 61}Ni) following thermal-neutron capture by the stable {sup 58}Ni, radioactive {sup 59}Ni, and stable {sup 60}Ni isotopes. Most of these {gamma} rays have been incorporated into the corresponding level schemes consisting of 65 levels in {sup 59}Ni, 88 levels in {sup 60}Ni, and 40 levels in {sup 61}Ni. The measured neutron separation energies (S{sub n} in keV) for {sup 59}Ni, {sup 60}Ni, and {sup 61}Ni are, respectively, 8999.28{+-}0.05, 11 387.73{+-}0.05, and 7820.11{+-}0.05. The measured thermal-neutron capture cross sections (in barns) for {sup 58}Ni, {sup 59}Ni, and {sup 60}Ni are, respectively, 4.13{+-}0.05, 73.7{+-}1.8, and 2.34{+-}0.05. In all three cases, primary electric-dipole (E1) transitions account for the bulk of the total capture cross section. We have calculated these E1 partial cross sections (in {sup 59}Ni and {sup 61}Ni) using direct-capture theory and models of compound-nuclear capture. The agreement between theory and experiment is good. The experimental level schemes have been compared with the results from a large-basis shell-model calculation. The agreement was also found to be quite good.

Raman, S.; Ouyang Xiaoping; Islam, M.A.; Starner, J.W.; Jurney, E.T.; Lynn, J.E.; Martinez-Pinedo, G. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); ICREA and Institut d'Estudis Espacials de Catalunya, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)

2004-10-01

302

Status of the Neutron Capture Measurement on 237Np with the DANCE Array at LANSCE  

SciTech Connect

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.

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. [Los Alamos National Laboratory, Los Alamos, NM, 87544 (United States); Alpizar-Vicente, A.; Greife, U.; Hatarik, R. [Colorado School of Mines, Golden, Co 80401 (United States)

2005-05-24

303

Neutron capture cross section measurements at the beam line 04 of J-PARC/MLF  

SciTech Connect

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.

Igashira, Masayuki; Harada, Hideo; Kiyanagi, Yoshiaki [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, O-okayama 2-12-1-N1-26, Meguro-ku, Tokyo 152-8550 (Japan); Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Shirakata-shirane 2-4, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Graduate School of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan)

2012-11-12

304

Neutron detection efficiency and capture product energy spectra of all-semiconducting-boron carbide and conversion-layer detectors  

Microsoft Academic Search

Solid-state neutron detectors based only on boron-rich semiconductor are of interest for their potential to provide the highest thermal neutron detection efficiencies of any solid-state neutron detectors. A simplified physical model is shown to generate capture product spectra that agree quantitatively with full-physics GEANT4 simulation. Using this model, comparisons are made between the ideal capture-product energy spectra of planar conversion

A. D. Harken; C. N. Lundstedt; E. E. Day; B. W. Robertson

2004-01-01

305

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

306

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

SciTech Connect

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.

Zhang, Yang [ORNL; Tyagi, M. [NCNR and University of Maryland; Mamontov, Eugene [ORNL; Chen, Sow-hsin H [ORNL

2011-01-01

307

Radiative Capture of Neutrons on 12C at Astrophysical Energies  

NASA Astrophysics Data System (ADS)

Within the framework of the potential cluster model with classification of orbital state according to the Young schemes, the possibility of a description of experimental data for the total cross sections of radiative n 12C capture at energies from 25 meV (25?10-3 eV) to 550 keV to the ground state and three excited levels of the 13? nucleus is considered. It is shown that it is entirely possible to explain the magnitude of the cross sections in the considered energy range on the basis of only E1 transitions from various states of n 12C scattering to these bound states of the 13C nucleus in the n 12C channel.

Dubovichenko, S. B.

2013-12-01

308

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

SciTech Connect

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.

Powell, J.; Ludewig, H.; Todosow, M.; Reich, M. [Brookhaven National Lab., Upton, NY (United States). Dept. of Advanced Technology

1995-06-01

309

Optimization study for an epithermal neutron beam for boron neutron capture therapy at the University of Virginia Research Reactor  

SciTech Connect

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.

Burns, T.D. Jr.

1995-05-01

310

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

SciTech Connect

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.

Mitchell, H.E.

1996-04-01

311

Improvement of dose distribution by central beam shielding in boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

Since boron neutron capture therapy (BNCT) with epithermal neutron beams started at the Kyoto University Reactor (KUR) in June 2002, nearly 200 BNCT treatments have been carried out. The epithermal neutron irradiation significantly improves the dose distribution, compared with the previous irradiation mainly using thermal neutrons. However, the treatable depth limit still remains. One effective technique to improve the limit is the central shield method. Simulations were performed for the incident neutron energies and the annular components of the neutron source. It was clear that thermal neutron flux distribution could be improved by decreasing the lower energy neutron component and the inner annular component of the incident beam. It was found that a central shield of 4-6 cm diameter and 10 mm thickness is effective for the 12 cm diameter irradiation field. In BNCT at KUR, the depth dose distribution can be much improved by the central shield method, resulting in a relative increase of the dose at 8 cm depth by about 30%. In addition to the depth dose distribution, the depth dose profile is also improved. As the dose rate in the central area is reduced by the additional shielding, the necessary irradiation time, however, increases by about 30% compared to normal treatment.

Sakurai, Yoshinori; Ono, Koji

2007-12-01

312

Improvement of dose distribution by central beam shielding in boron neutron capture therapy.  

PubMed

Since boron neutron capture therapy (BNCT) with epithermal neutron beams started at the Kyoto University Reactor (KUR) in June 2002, nearly 200 BNCT treatments have been carried out. The epithermal neutron irradiation significantly improves the dose distribution, compared with the previous irradiation mainly using thermal neutrons. However, the treatable depth limit still remains. One effective technique to improve the limit is the central shield method. Simulations were performed for the incident neutron energies and the annular components of the neutron source. It was clear that thermal neutron flux distribution could be improved by decreasing the lower energy neutron component and the inner annular component of the incident beam. It was found that a central shield of 4-6 cm diameter and 10 mm thickness is effective for the 12 cm diameter irradiation field. In BNCT at KUR, the depth dose distribution can be much improved by the central shield method, resulting in a relative increase of the dose at 8 cm depth by about 30%. In addition to the depth dose distribution, the depth dose profile is also improved. As the dose rate in the central area is reduced by the additional shielding, the necessary irradiation time, however, increases by about 30% compared to normal treatment. PMID:18065847

Sakurai, Yoshinori; Ono, Koji

2007-12-21

313

A comparison of the COG and MCNP codes in computational neutron capture therapy modeling, Part II: gadolinium neutron capture therapy models and therapeutic effects.  

PubMed

The goal of this study was to evaluate the COG Monte Carlo radiation transport code, developed and tested by Lawrence Livermore National Laboratory, for gadolinium neutron capture therapy (GdNCT) related modeling. The validity of COG NCT model has been established for this model, and here the calculation was extended to analyze the effect of various gadolinium concentrations on dose distribution and cell-kill effect of the GdNCT modality and to determine the optimum therapeutic conditions for treating brain cancers. The computational results were compared with the widely used MCNP code. The differences between the COG and MCNP predictions were generally small and suggest that the COG code can be applied to similar research problems in NCT. Results for this study also showed that a concentration of 100 ppm gadolinium in the tumor was most beneficial when using an epithermal neutron beam. PMID:16010124

Wangerin, K; Culbertson, C N; Jevremovic, T

2005-08-01

314

In-phantom two-dimensional thermal neutron distribution for intraoperative boron neutron capture therapy of brain tumours.  

PubMed

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. PMID:12171329

Yamamoto, T; Matsumura, A; Yamamoto, K; Kumada, H; Shibata, Y; Nose, T

2002-07-21

315

A parameter study to determine the optimal source neutron energy in boron neutron capture therapy of brain tumours.  

PubMed

The values of the parameters used in boron neutron capture therapy (BNCT) to calculate a given dose to human tissue vary with patients due to different physical, biological and/or medical circumstances. Parameters include the tissue dimensions, the 10B concentration and the relative biological effectiveness (RBE) factors for the different dose components associated with BNCT. Because there is still no worldwide agreement on RBE values, more often than not, average values for these parameters are used. It turns out that the RBE-problem can be circumvented by taking into account all imaginable parameter values. Approaching this quest from another angle: the outcome will also provide the parameters (and values) which influence the optimal source neutron energy. For brain tumours it turns out that the 10B concentration, the RBE factors for 10B as well as fast neutrons, together with the dose limit set for healthy tissue, affect the optimal BNCT source neutron energy. By using source neutrons of a few keV together with neutrons of a few eV, it ensures that, under all imaginable circumstances, a maximum of alpha (and lithium) particles can be delivered in the tumour. PMID:15509065

Nievaart, V A; Moss, R L; Kloosterman, J L; van der Hagen, T H J J; van Dam, H

2004-09-21

316

EPICS Slow Controls System in the Search for a Neutron Electric Dipole Moment  

NASA Astrophysics Data System (ADS)

The measurement of a nonzero electric dipole moment (EDM) of the neutron would significantly impact our understanding of the nature of the electro-weak and strong interactions. The goal of the current experiment is to improve the measurement sensitivity of the EDM by two orders of magnitude. The experiment is based on the magnetic-resonance technique of rotating a magnetic dipole moment in a magnetic field. The measurement of the neutron EDM comes from a measurement of the difference in the precession frequencies of neutrons when a strong electric field parallel to the magnetic field is reversed. This construction project is divided into a number of subsystems, five of which require automated control. The Experimental Physics and Industrial Control System (EPICS) is a slow-controls data acquisition (DAQ) system and is the system of choice for this experiment. It was selected for both its ease of use and ability to act as a total control system for large systems. As part of the initial research and development for the EDM project, we are setting up a prototype system that will eventually be copied and sent to the subsystem managers. This prototype consists of a VME crate housing a single board computer and DAQ modules. EPICS, running on a PC with CentOS Linux-x86, interfaces with the VME single board computer and provides a graphical user interface for the control system. The details on building this prototype DAQ system will be presented. Supported in part by the U.S. DoE.

Taylor, Courtney

2006-10-01

317

[Epithermal neutron capture therapy]. Progress and status report  

SciTech Connect

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.

Not Available

1993-05-01

318

Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium  

SciTech Connect

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.

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

319

Determination of the parahydrogen fraction in a liquid hydrogen target using energy-dependent slow neutron transmission  

NASA Astrophysics Data System (ADS)

The NPDGamma collaboration is performing a measurement of the very small parity-violating asymmetry in the angular distribution of the 2.2 MeV ?-rays from the capture of polarized cold neutrons on protons (A?). The estimated size of A? is 5×10-8, and the measured asymmetry is proportional to the neutron polarization upon capture. Since the interaction of polarized neutrons with one of the two hydrogen molecular states (orthohydrogen) can lead to neutron spin-flip scattering, it is essential that the hydrogen in the target is mostly in the molecular state that will not depolarize the neutrons (?99.8% parahydrogen). For that purpose, in the first stage of the NPDGamma experiment at the Los Alamos Neutron Science Center (LANSCE), we operated a 16-l liquid hydrogen target, which was filled in two different occasions. The parahydrogen fraction in the target was accurately determined in situ by relative neutron transmission measurements. The result of these measurements indicate that the fraction of parahydrogen in equilibrium was 0.9998±0.0002 in the first data taking run and 0.9956±0.0002 in the second. We describe the parahydrogen monitor system, relevant aspects of the hydrogen target, and the procedure to determine the fraction of parahydrogen in the target. Also assuming thermal equilibrium of the target, we extract the scattering cross-section for neutrons on parahydrogen.

Barrón-Palos, L.; Alarcon, R.; Balascuta, S.; Blessinger, C.; Bowman, J. D.; Chupp, T. E.; Covrig, S.; Crawford, C. B.; Dabaghyan, M.; Dadras, J.; Dawkins, M.; Fox, W.; Gericke, M. T.; Gillis, R. C.; Lauss, B.; Leuschner, M. B.; Lozowski, B.; Mahurin, R.; Mason, M.; Mei, J.; Nann, H.; Penttilä, S. I.; Ramsay, W. D.; Salas-Bacci, A.; Santra, S.; Seo, P.-N.; Sharma, M.; Smith, T.; Snow, W. M.; Wilburn, W. S.; Yuan, V.

2011-12-01

320

The NPDGamma experiment - A measurement of parity violation in polarized cold neutron capture on parahydrogen  

NASA Astrophysics Data System (ADS)

The NPDGamma experiment aims to measure the correlation between the neutron spin and the direction of the emitted photon in neutron-proton capture. An up-down parity violating asymmetry from this process can be directly related to the strength of the hadronic weak interaction between nucleons. The methodology and results from the first run of this experiment, completed at LANSCE in 2006, will be discussed. The next phase of the experiment is currently being commissioned on the Fundamental Neutron Physics Beamline of the Spallation Neutron Source at ORNL. We will discuss the improvements in the apparatus and show commissioning data. The upcoming run is expected to yield a measurement with a projected statistical error of 1x10-8 as well as negligible systematic errors. This will finally allow the result can be compared with theoretical predictions.

Fomin, Nadia

2011-04-01

321

Gel dosimeters as useful dose and thermal-fluence detectors in boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

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.

Gambarini, G.; Moss, R. L.; Mariani, M.; Carrara, M.; Daquino, G. G.; Nievaart, V. A.; Valente, M.; Vanossi, E.

322

Final Stage in the Design of a Boron Neutron Capture Therapy facility at CEADEN, Cuba  

NASA Astrophysics Data System (ADS)

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

Cabal, F. Padilla; Martín, G.

2008-08-01

323

MAGIC polymer gel for dosimetric verification in boron neutron capture therapy.  

PubMed

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

Uusi-Simola, Jouni; Heikkinen, Sami; Kotiluoto, Petri; Serén, Tom; Seppälä, Tiina; Auterinen, Iiro; Savolainen, Sauli

2007-01-01

324

Diversity of abundance patterns of neutron-capture elements in very metal-poor stars  

SciTech Connect

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.

Aoki, Misa; Ishimaru, Yuhri [International Christian University 10-2, Osawa, Mitaka, Tokyo 181-0015 (Japan); Aoki, Wako; Wanajo, Shinya [National Astronomical Observatory of Japan (NAOJ) 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan)

2014-05-02

325

Neutron Capture and Transmission Measurements on 103Rh Down to Thermal Energies  

SciTech Connect

The neutron total and capture cross sections of 103Rh have been measured in the energy region from 0.01 eV to 1 keV at the Time-of-Flight facility GELINA of the Institute for Reference Materials and Measurements in Geel (B). The transmission measurements on two samples of rhodium were carried out at a 50-m flight path using a Li-glass scintillator. The capture-detection system, which is installed at a 14.5-m flight path, is based on the total-energy detection principle. The system consists of two C6D6 detectors and a 10B ionisation chamber that determines the shape of the neutron flux. A pulse-height weighting function was used to ensure that the efficiency for a neutron-capture event was independent from the gamma cascade. The data have been normalized to the well-isolated and saturated 103Rh resonance at 1.26 eV. The resonance parameters for 103Rh were obtained from a simultaneous shape analysis of the capture and transmission data using the REFIT code.

Brusegan, A.; Borella, A.; Siegler, P.; Schillebeeckx, P. [EC-JRC-IRMM, Retieseweg 111, B-2440 Geel (Belgium); Berthoumieux, E.; Gunsing, F. [CEA DAPNIA/SPhN F-91911 Gif-sur-Yvette CEDEX (France); Moxon, M. [3 Hyde Copse, Marcham (United Kingdom)

2005-05-24

326

Diversity of abundance patterns of neutron-capture elements in very metal-poor stars  

NASA Astrophysics Data System (ADS)

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.

Aoki, Misa; Aoki, Wako; Ishimaru, Yuhri; Wanajo, Shinya

2014-05-01

327

A simple method for the analysis of neutron resonance capture spectra  

SciTech Connect

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.

Clarijs, Martijn C.; Bom, Victor R.; Eijk, Carel W. E. van [Radiation, Detection and Medical Imaging, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)

2009-03-15

328

Dosimetric implications of new compounds for neutron capture therapy (NCT)  

SciTech Connect

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)

Fairchild, R.G.

1982-01-01

329

Commercial Clinical Application of Boron Neutron Capture Therapy  

SciTech Connect

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.

N /A

1999-09-03

330

Rates for neutron-capture reactions on tungsten isotopes in iron meteorites. [Abstract only  

NASA Technical Reports Server (NTRS)

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.

Masarik, J.; Reedy, R. C.

1994-01-01

331

Rates for neutron-capture reactions on tungsten isotopes in iron meteorites  

NASA Astrophysics Data System (ADS)

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 10-4 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.

Masarik, J.; Reedy, R. C.

1994-07-01

332

Enhancement of dark matter capture by neutron stars in binary systems.  

PubMed

We study the capture of dark matter particles by neutron stars in close binary systems. By performing a direct numerical simulation, we find that there is a sizable amplification of the rate of dark matter capture by each of the companions. In the case of the binary pulsar PSR J1906+0746 with the orbital period of 4 hours the amplification factor is approximately equal to 3.5. This amplification can be attributed to the energy loss by dark matter particles resulting from their gravitational scattering off moving companions. PMID:23006256

Brayeur, Lionel; Tinyakov, Peter

2012-08-10

333

Boron neutron capture therapy (BNCT) in Finland: technological and physical prospects after 20 years of experiences.  

PubMed

Boron Neutron Capture Therapy (BNCT) is a binary radiotherapy method developed to treat patients with certain malignant tumours. To date, over 300 treatments have been carried out at the Finnish BNCT facility in various on-going and past clinical trials. In this technical review, we discuss our research work in the field of medical physics to form the groundwork for the Finnish BNCT patient treatments, as well as the possibilities to further develop and optimize the method in the future. Accordingly, the following aspects are described: neutron sources, beam dosimetry, treatment planning, boron imaging and determination, and finally the possibilities to detect the efficacy and effects of BNCT on patients. PMID:22613369

Savolainen, Sauli; Kortesniemi, Mika; Timonen, Marjut; Reijonen, Vappu; Kuusela, Linda; Uusi-Simola, Jouni; Salli, Eero; Koivunoro, Hanna; Seppälä, Tiina; Lönnroth, Nadja; Välimäki, Petteri; Hyvönen, Heini; Kotiluoto, Petri; Serén, Tom; Kuronen, Antti; Heikkinen, Sami; Kosunen, Antti; Auterinen, Iiro

2013-05-01

334

Data Acquisition System for the Detector for Advanced Neutron Capture Experiments (DANCE)  

NASA Astrophysics Data System (ADS)

Nuclear and high energy physics experiments continue to grow in complexity. This increase in "experimental" complexity requires a matching increase in the complexity of the system used to acquire the data from the experimental apparatus. The Detector for Advanced Neutron Capture Experiments (DANCE), a 4? BaF2 array located at the Manuel J. Lujan Jr. Neutron Scattering Center at Los Alamos National Laboratory is a prime example of this increasing experimental complexity. We will describe several of the important issues that arose during the development of a data acquisition system based on MIDAS/ROOT, and the methods used to overcome these issues.

Bredeweg, T. A.; Reifarth, R.; Ullmann, J. L.; Haight, R. C.; O'Donnell, J. M.; Wouters, J. M.; Wilhelmy, J. B.; Rundberg, R. S.; Vieira, D. J.

2003-04-01

335

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

NASA Astrophysics Data System (ADS)

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.

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

336

Feasibility study on pinhole camera system for online dosimetry in boron neutron capture therapy.  

PubMed

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

Katabuchi, Tatsuya; Hales, Brian; Hayashizaki, Noriyosu; Igashira, Masayuki; Khan, Zareen; Kobayashi, Tooru; Matsuhashi, Taihei; Miyazaki, Koichi; Ogawa, Koichi; Terada, Kazushi

2014-06-01

337

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

SciTech Connect

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.

Kreiner, A. J. [Departamento de Fisica, Comision Nacional de Energia Atomica (Argentina); Escuela de Ciencia y Tecnologia, Universidad de Gral San Martin (Argentina); CONICET, (Argentina); Kwan, J. W.; Henestroza, E. [Ernest Orlando Lawrence Berkeley National Laboratory, Univ. of California, Berkeley, CA (United States); Burlon, A. A.; Di Paolo, H.; Minsky, D.; Debray, M. [Departamento de Fisica, Comision Nacional de Energia Atomica, (Argentina); Escuela de Ciencia y Tecnologia, Universidad de Gral San Martin (Argentina); Valda, A.; Somacal, H. R. [Escuela de Ciencia y Tecnologia, Universidad de Gral San Martin (Argentina)

2007-02-12

338

Neutron Capture Elements in the Open Cluster Chemical Abundance & Mapping (OCCAM) Survey  

NASA Astrophysics Data System (ADS)

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.

O'Connell, Julia; Frinchaboy, Peter M.; Shetrone, Matthew D.; Hearty, Fred R.; Majewski, Steven R.; Zasowski, Gail; Sdss /Apogee-1, III

2015-01-01

339

Using 171,173Yb(d,p) to benchmark a surrogate reaction for neutron capture  

SciTech Connect

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.

Hatarik, R; Bersntein, L; Burke, J; Cizewski, J; Gibelin, J; Lesher, S; O'Malley, P; Phair, L; Swan, T

2008-08-08

340

Numerical characterization of a tomographic system for online dose measurements in Boron Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

A tomographic system for online dose measurements in Boron Neutron Capture Therapy (BNCT) based on the measurement of a specific 478 keV ?-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.

Minsky, D. M.; Valda, A. A.; Burlon, A. A.; Kreiner, A. J.; Somacal, H.

2007-02-01

341

Numerical characterization of a tomographic system for online dose measurements in Boron Neutron Capture Therapy  

SciTech Connect

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.

Minsky, D. M.; Valda, A. A.; Somacal, H. [Escuela de Ciencia y Tecnologia (UNSAM), San Martin, Buenos Aires (Argentina); Dpto. de Fisica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Burlon, A. A. [Escuela de Ciencia y Tecnologia (UNSAM), San Martin, Buenos Aires (Argentina); Dpto. de Fisica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Fundacion J.B. Sauberan (Argentina); Kreiner, A. J. [Escuela de Ciencia y Tecnologia (UNSAM), San Martin, Buenos Aires (Argentina); Dpto. de Fisica, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Buenos Aires (Argentina); CONICET (Argentina)

2007-02-12

342

Heterogeneous slow dynamics of imidazolium-based ionic liquids studied by neutron spin echo.  

PubMed

We have investigated structure and relaxation phenomena for ionic liquids 1-octyl-3-methylimidazolium hexafluorophosphate (C8mimPF6) and bis(trifluoromethylsulfonyl)imide (C8mimTFSI) by means of neutron diffraction and neutron spin echo (NSE) techniques. The diffraction patterns show two distinct peaks appeared at scattering vectors Q of 0.3 and 1.0 Å(-1). The former originates from the nanoscale structure characteristic to ionic liquids and the latter due to the interionic correlations. Interestingly, the intensity of the low-Q peak drastically grows upon cooling and keeps growing even below the glass transition temperature. The NSE measurements have been performed at these two Q positions, to explore the time evolution of each correlation. The relaxation related to the ionic correlation (ionic diffusion) is of Arrhenius-type and exhibits nonexponential behavior. The activation energy (Ea) of the ionic diffusion, which is linked to viscosity, depends on the type of anion; the larger is the anion size, the smaller Ea becomes for most of anions. On the other hand, two kinds of relaxation processes, slower and faster ones, are found at the low-Q peak position. The most significant finding is that the fraction of the slower relaxation increases and that of the faster one decreases upon cooling. Combining the NSE data with the diffraction data, we conclude that there exist two parts in ILs: one with the ordered nanostructure exhibiting the slow relaxation, and the other with disordered structure showing faster relaxation. The structure and dynamics of ILs are heterogeneous in nature, and the fraction of each part changes with temperature. PMID:23391265

Kofu, Maiko; Nagao, Michihiro; Ueki, Takeshi; Kitazawa, Yuzo; Nakamura, Yutaro; Sawamura, Syota; Watanabe, Masayoshi; Yamamuro, Osamu

2013-03-01

343

A New Thermal Neutron Flux Convention  

Microsoft Academic Search

A new thermal neutron flux convention is proposed where the neutron slowing down spectrum per unit energy varies as 1\\/E1+? (| ? ln E | << 1). The neutron capture rate per atom for a detector may be written as n?0 ?0 [Gthg(T) + f C(?, T) Grh(?, Gr)I'\\/?0] where n is the neutron density, ?0 is the conventional 2200

T B Ryves

1969-01-01

344

Monte Carlo based treatment planning systems for Boron Neutron Capture Therapy in Petten, The Netherlands  

Microsoft Academic Search

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,?)7Li reaction, in comparison with the surrounding healthy cells. In Petten (The Netherlands), at the High Flux Reactor, a

V A Nievaart; G G Daquino; R L Moss

2007-01-01

345

Parity violation in neutron–proton capture—The NPDGamma experiment  

Microsoft Academic Search

The NPDGamma collaboration has recently completed the first phase of a measurement to determine the size of the weak nucleon–nucleon interaction from cold neutron capture on a liquid hydrogen target. In the framework of the nearly 30 year old DDH model [B. Desplanques, J.F. Donoghue, B.R. Holstein, Annals of Physics 124 (1980) 449], the measured process is explained in terms

Michael Gericke; S. Page; D. Ramsay; R. Alarcon; S. Balascuta; L. Barron; J. D. Bowman; R. D. Carlini; W. Chen; T. E. Chupp; C. Crawford; S. Covrig; M. Dabaghyan; S. J. Freedman; T. R. Gentile; R. C. Gillis; G. L. Greene; F. W. Hersman; T. Ino; G. L. Jones; B. Lauss; M. Leuschner; B. Losowki; R. Mahurin; Y. Masuda; J. Mei; G. S. Mitchell; S. Muto; H. Nann; S. I. Penttilä; A. Salas-Bacci; S. Santra; P.-N. Seo; E. Sharapov; M. Sharma; T. Smith; W. M. Snow; W. S. Wilburn; V. Yuan

2009-01-01

346

Proton injection and RF capture in the national spallation neutron source  

SciTech Connect

The accelerator system for the 1 to 5 MW National Spallation Neutron Source (NSNS) consists of a linac followed by a 1 GeV proton accumulator ring. Since the ring is a very high current machine, the injection and rf capture of the protons is deeply affected by transverse and longitudinal space charge effects. Results of numerical simulation of the process are presented together with considerations on methods and results of space charge treatment in high intensity proton storage rings.

Luccio, A.U.; Beebe-Wang, J.; Maletic, D. [and others

1997-08-01

347

Boron Neutron Capture Therapy in the Treatment of Locally Recurred Head and Neck Cancer  

Microsoft Academic Search

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

Leena Kankaanranta; Tiina Seppaelae; Hanna Koivunoro; Kauko Saarilahti; Timo Atula; Juhani Collan; Eero Salli; Mika Kortesniemi; Jouni Uusi-Simola; Antti Maekitie; Marko Seppaenen; Heikki Minn; Petri Kotiluoto; Iiro Auterinen; Sauli Savolainen; Mauri Kouri; Heikki Joensuu

2007-01-01

348

Neutron Capture Elements in s-Process-Rich, Very Metal-Poor Stars  

Microsoft Academic Search

We report abundance estimates for neutron capture elements, including lead (Pb), and nucleosynthesis models for their origin, in two carbon-rich, very metal-poor stars, LP 625-44 and LP 706-7. These stars are subgiants whose surface abundances are likely to have been strongly affected by mass transfer from companion asymptotic giant branch (AGB) stars that have since evolved to white dwarfs. The

Wako Aoki; Sean G. Ryan; John E. Norris; Timothy C. Beers; Hiroyasu Ando; Nobuyuki Iwamoto; Toshitaka Kajino; Grant J. Mathews; Masayuki Y. Fujimoto

2001-01-01

349

Gamma-ray cascade transitions from resonant neutron capture in Cd-111 and Cd-113  

SciTech Connect

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.

Rusev, Gencho Y. [Los Alamos National Laboratory

2012-08-27

350

Case numbers for a randomized clinical trial of boron neutron capture therapy for Glioblastoma multiforme.  

PubMed

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

Sander, Anja; Wosniok, Werner; Gabel, Detlef

2014-06-01

351

Boron neutron capture therapy for oral precancer: proof of principle in an experimental animal model  

SciTech Connect

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.

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

352

Analytical sensitivities and energies of thermal-neutron-capture gamma rays  

USGS Publications Warehouse

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.

Duffey, D.; El-Kady, A.; Senftle, F.E.

1970-01-01

353

Analytical sensitivities and energies of thermal neutron capture gamma rays II  

USGS Publications Warehouse

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.

Senftle, F.E.; Moore, H.D.; Leep, D.B.; El-Kady, A.; Duffey, D.

1971-01-01

354

DNA double-strand break induction in Ku80-deficient CHO cells following Boron Neutron Capture Reaction  

PubMed Central

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

2011-01-01

355

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

PubMed

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

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

356

Study of Neutron-Capture Element Abundances in Metal-Poor Stars  

NASA Astrophysics Data System (ADS)

This work describes a study of elemental abundances for 30 metal-poor stars whose chemical abundances provide excellent information for setting constraints on models of neutron-capture processes. Based on the abundances of main r-process stars, the abundance patterns of main r-process and weak r-process are obtained. The two r>-process component coefficients are defined to determine the relative contributions from individual neutron-capture process to abundances of metal-poor stars. Based on the component coefficients, we find that metal-poor stars BD+42621 and HD 4306 are also weak r-process stars, which means that the abundance pattern produced by weak r-process is stable. All metal-poor star abundances contain the contributions of both main r-process and weak r-process. The elements produced by weak r-process have increased along with Fe over the polluted history. Most of the metal-poor star abundances do not follow the pattern observed in the solar system, but there is a small fraction that do. For the low-[Sr/Fe] star BD-185550 ([Sr/Fe] ? -1), neutron-capture element abundances can be explained by the mixture of two r-process components. Since lighter elements in this star cannot be fitted by the two components, the abundance pattern of P-component is estimated from those abundances.

Li, Hongjie; Shen, Xiaojing; Liang, Shuai; Cui, Wenyuan; Zhang, Bo

2013-02-01

357

Experimental boron neutron capture therapy for melanoma: Systemic delivery of boron to melanotic and amelanotic melanoma  

SciTech Connect

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.

Coderre, J.A.; Glass, J.D.; Micca, P.; Greenberg, D. (Brookhaven National Lab., Upton, NY (United States)); Packer, S. (Brookhaven National Lab., Upton, NY (United States) North Shore University Hospital Manhasset, NY (United States))

1990-01-01

358

Boron neutron capture therapy of brain tumors: an emerging therapeutic modality.  

PubMed

Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10, a stable isotope, is irradiated with low-energy thermal neutrons to yield alpha particles and recoiling lithium-7 nuclei. For BNCT to be successful, a large number of 10B atoms must be localized on or preferably within neoplastic cells, and a sufficient number of thermal neutrons must be absorbed by the 10B atoms to sustain a lethal 10B (n, alpha) lithium-7 reaction. There is a growing interest in using BNCT in combination with surgery to treat patients with high-grade gliomas and possibly metastatic brain tumors. The present review covers the biological and radiobiological considerations on which BNCT is based, boron-containing low- and high-molecular weight delivery agents, neutron sources, clinical studies, and future areas of research. Two boron compounds currently are being used clinically, sodium borocaptate and boronophenylalanine, and a number of new delivery agents are under investigation, including boronated porphyrins, nucleosides, amino acids, polyamines, monoclonal and bispecific antibodies, liposomes, and epidermal growth factor. These are discussed, as is optimization of their delivery. Nuclear reactors currently are the only source of neutrons for BNCT, and the fission reaction within the core produces a mixture of lower energy thermal and epithermal neutrons, fast or high-energy neutrons, and gamma-rays. Although thermal neutron beams have been used clinically in Japan to treat patients with brain tumors and cutaneous melanomas, epithermal neutron beams now are being used in the United States and Europe because of their superior tissue-penetrating properties. Currently, there are clinical trials in progress in the United States, Europe, and Japan using a combination of debulking surgery and then BNCT to treat patients with glioblastomas. The American and European studies are Phase I trials using boronophenylalanine and sodium borocaptate, respectively, as capture agents, and the Japanese trial is a Phase II study. Boron compound and neutron dose escalation studies are planned, and these could lead to Phase II and possibly to randomized Phase III clinical trials that should provide data regarding therapeutic efficacy. PMID:10069580

Barth, R F; Soloway, A H; Goodman, J H; Gahbauer, R A; Gupta, N; Blue, T E; Yang, W; Tjarks, W

1999-03-01

359

Coulomb Dissociation of $^{15}$C and Radiative Neutron Capture on $^{14}$C  

E-print Network

The semiclassical, dynamical description of diffraction dissociation of weakly bound nuclei is applied to analyze the decay-energy spectra of $^{15}$C that have been measured at 68 MeV/nucleon on a Pb target. The optical potentials that are used to describe the nuclear interaction of $^{15}$C with the target nucleus are realistic because the fits to the two measured spectra, one with a small and one with a very large acceptance angle, are consistent and of similar quality. The cross section for the radiative neutron capture on $^{14}$C to the 1/2$^+$ ground state of $^{15}$C is deduced from the analysis. When combined with an estimated contribution from the capture to the 5/2$^+$ excited state of $^{15}$C, an excellent agreement with a recent direct capture measurement is achieved.

H. Esbensen

2009-08-24

360

Proton vs. neutron captures in the neutrino winds of core-collapse supernovae  

NASA Astrophysics Data System (ADS)

Recent one-dimensional (1D) hydrodynamical simulations of core-collapse supernovae (CCSNe) with a sophisticated treatment of neutrino transport indicate the neutrino-driven winds being proton-rich all the way until the end of their activity. This seems to exclude all possibilities of neutron-capture nucleosynthesis, but provide ideal conditions for the ?p-process, in neutrino winds. New 2D explosion simulations of electron-capture supernovae (ECSNe; a subset of CCSNe) exhibit, however, convective neutron-rich lumps, which are absent in the 1D case. Our nucleosynthesis calculations indicate that these neutron-rich lumps allow for interesting production of elements between iron group and N = 50 nuclei (Zn, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, with little Ga). Our models do not confirm ECSNe as sources of the strong r-process (but possibly of a weak r-process up to Pd, Ag, and Cd in the neutron-rich lumps) nor of the ?p-process in the subsequent proton-rich outflows. We further study the ?p-process with semi-analytic models of neutrino winds assuming the physical conditions for CCSNe. We also explore the sensitivities of some key nuclear reaction rates to the nucleosynthetic abundances. Our result indicates that the ?/p-process in CCSNe (other than ECSNe) can be the origin of p-nuclei up to A = 108, and even up to A = 152 in limiting conditions.

Wanajo, S.; Janka, H.-T.; Müller, B.; Kubono, S.

2011-09-01

361

Feasibility of using prompt neutron capture gamma rays to detect mercury  

SciTech Connect

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.

Bell, Z.W.

1993-10-01

362

Low-lying levels of 77Se studied by thermal neutron capture and evidence for a new term in the E2 operator of RQM (IBM)  

NASA Astrophysics Data System (ADS)

A high-resolution study of the 76Se(n, ?) reaction was carried out with curved-crystal and pair spectrometers and conversion electrons were measured following slow-neutron capture. The resulting data yield very precise level energies and spin and parity assignments for most of the levels. The neutron separation energy of 77Se was measured as 7418.85 ± 0.07 keV. The experimental data were compared with theoretical results for the level energies in 77Se and the E2, M1 and E1 branching ratios obtained from the SU(6) particle-vibration model (PTQM). We used 76Se as a slightly perturbed SU(5) vibrational core and the particle-vibration interaction strengths from the PTQM calculation for 75Se. In this frame there is evidence for a ?n = 2 term in the E2 operator. This term has not been included so far in TQM and IBM calculations.

Tokunaga, Y.; Seyfarth, H.; Meyer, R. A.; Schult, O. W. B.; Börner, H. G.; Barreau, G.; Faust, H. R.; Schreckenbach, K.; Brant, S.; Paar, V.; Vouk, M.; Vretenar, D.

1985-06-01

363

Krypton and xenon in Apollo 14 samples - Fission and neutron capture effects in gas-rich samples  

NASA Technical Reports Server (NTRS)

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.

Drozd, R.; Hohenberg, C.; Morgan, C.

1975-01-01

364

High Resolution Quantitative Auto-Radiography to determine microscopic distributions of B-10 in neutron capture therapy  

E-print Network

The success of Boron Neutron Capture Therapy (BNCT) is heavily dependent on the microscopic distribution of B-10 in tissue. High Resolution Quantitative Auto-Radiography (HRQAR) is a potentially valuable analytical tool ...

Harris, Thomas C. (Thomas Cameron)

2006-01-01

365

Evaluation of neutron dosimetry on pancreatic cancer phantom model for application of intraoperative boron neutron-capture therapy.  

PubMed

Pancreatic cancer is one of the most difficult neoplasms to cure and there is a need for new combinated therapy. If sufficient boron compound can be targeted accurate to the tumour, Boron Neutron-Capture Therapy (BNCT) can be applied to pancreatic cancer. We administrated BNCT to a cancer with pancreatic cancer patient using intraoperative irradiation. In this study, we performed preliminary dosimetry of a phantom model of the abdominal cavity. The flux of 8>x10(7)n/cm(2)/s (0.1 ratio) was 4.5 cm in depth from the surface in the case of simple irradiation, and the field of thermal neutrons was spread as 13 cm and 11.5 cm were usage of Void and Void with LiF collimation, respectively in thermal (OO-0011) mode. In the case of epithermal (CO-0000) mode, epithermal and fast components are four times higher at the surface level. In the case of mixed beam (OO-0000) mode, thermal neutron flux was the same as thermal neutron mode at a depth of 10 cm, but the gamma-ray component was two times higher than that of thermal neutron mode. With the use of Void and LiF collimation, thermal neutrons were selectively applied to the tumour combined with the CT-imaging of the cancer patient. This means that we could irradiate the tumour selectively and safely as possible, reducing the effects on neighboring healthy tissues. High resolution whole body dosimetry will be necessary to extend the application of BNCT to pancreatic cancer. PMID:17614250

Yanagie, Hironobu; Sakurai, Yosiyuki; Ogura, Koichi; Kobayashi, Tooru; Furuya, Yoshitaka; Sugiyama, Hirotaka; Kobayashi, Hisao; Ono, Koji; Nakagawa, Keiichi; Takahashi, Hiroyuki; Nakazawa, Masaharu; Eriguchi, Masazumi

2007-09-01

366

Neutron dosimetry in boron neutron capture therapy using aqueous solutions of lithium acetate  

NASA Astrophysics Data System (ADS)

This paper presents the development of a dosimetry method, based on liquid scintillation (LS) counting of the tritium that is produced in aqueous solutions of lithium acetate, for the determination of the boron and nitrogen absorbed doses in-phantom in BNCT. The dosimeter is passive, integrating, approximately tissue equivalent, and insensitive to gamma rays and the elastic scattering of fast neutrons. The dosimetry method exhibits a response which is proportional to the boron and nitrogen absorbed doses and which can be calibrated to NIST standard solutions of water spiked with tritium. For 0.2 g of lithium acetate dissolved in a milliliter of water, the measured sensitivity is (1.73±0.04)×10 -9 cpm per unit of thermal neutron fluence (in neutrons/cm 2). For the LS analyzer that was used, the background signal was 12.84±0.02 cpm, yielding a thermal neutron fluence threshold for this detection method of approximately 7×10 9 neutrons/cm 2.

Rakovan, L. J.; Blue, T. E.; Vest, A. L.

367

Neodymium neutron transmission and capture measurements and development of a new transmission detector  

NASA Astrophysics Data System (ADS)

Neodymium is a 235U fission product and is important in reactor neutronic calculations. The aim of this thesis is to improve upon the existing neutron cross section data of neodymium. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute LINAC using metallic neodymium samples. The capture measurements were made at the 25-m flight station with a 16-segment Nal multiplicity detector, and the transmission measurements were performed at 15-m and 25-m flight stations, respectively, with 6Li glass scintillation detectors. After the data were collected and reduced, resonance parameters were determined by simultaneously fitting the transmission and capture data with the multilevel R-matrix Bayesian code SAMMY. The resonance parameters for all naturally occurring neodymium isotopes were deduced within the energy range of 1.0 eV to 500 eV. The resulting resonance parameters were used to calculate the capture resonance integral with this energy region and were compared to calculations obtained when using the resonance parameters from ENDF-B/VI. The RPI parameters gave a resonance integral value of 32 +/- 1 barns that is approximately 7% lower than that obtained with the ENDF-B/VI parameters. The current measurements significantly reduce the statistical uncertainties on the resonance parameters when compared with previously published parameters. This thesis also explains the resolution function in detail and discusses its importance when fitting experimental data to extract resonance parameters. More accurate resolution function parameters were determined for epithermal transmission and capture measurements by fitting well known resonances in Uranium-238. Improved transmission bare-bounce target in-beam photomultiplier tube (PMT) resolution function parameters were found and compared to those used previously at the RPI LINAC and a marked improvement in the quality of the fits is shown. In addition to finding improved resolution function parameters, a method was developed to find the 'estimated uncertainty' on these parameters. The 'estimated uncertainty' values for the resolution function parameters were chosen to represent a + or -10% change in the reduced chi-squared value in fits to uranium. This thesis also presents the design, construction, and implementation of a new out-of-beam detector (OBD) system for use in transmission experiments. MCNP modeling was used to validate that the OBD system has less neutron backscatter when compared with the previously used in-beam detector (IBD). This decrease in neutron backscatter offers an overall improvement in resolution function. Experiments were performed with the OBD system using uranium samples and resulting data was used to show this improvement in the resolution function.

Barry, Devin P.

368

Measurements of keV-NEUTRON Capture Cross Section and Gamma-Ray Spectra of 142Nd  

NASA Astrophysics Data System (ADS)

The neutron capture cross section and capture ?-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 ?-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 ?-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.

Katabuchi, T.; Igashira, M.; Tajika, M.; Nakamura, Y.; Kamada, S.; Terada, K.

2013-03-01

369

Preliminary treatment planning and dosimetry for a clinical trial of neutron capture therapy using a fission converter epithermal neutron beam.  

PubMed

A Phase I/II clinical trial of neutron capture therapy (NCT) was conducted at Harvard-MIT using a fission converter epithermal neutron beam. This epithermal neutron beam has nearly ideal performance characteristics (high intensity and purity) and is well-suited for clinical use. Six glioblastoma multiforme (GBM) patients were treated with NCT by infusion of the tumor-selective amino acid boronophenylalanine-fructose (BPA-F) at a dose of 14.0 g/m(2) body surface area over 90 min followed by irradiation with epithermal neutrons. Treatments were planned using NCTPlan and an accelerated version of the Monte Carlo radiation transport code MCNP 4B. Treatments were delivered in two fractions with two or three fields. Field order was reversed between fractions to equalize the average blood boron concentration between fields. The initial dose in the dose escalation study was 7.0 RBEGy, prescribed as the mean dose to the whole brain volume. This prescription dose was increased by 10% to 7.7 RBEGy in the second cohort of patients. A pharmacokinetic model was used to predict the blood boron concentration for determination of the required beam monitor units with good accuracy; differences between prescribed and delivered doses were 1.5% or less. Estimates of average tumor doses ranged from 33.7 to 83.4 RBEGy (median 57.8 RBEGy), a substantial improvement over our previous trial where the median value of the average tumor dose was 25.8 RBEGy. PMID:15308195

Kiger, W S; Lu, X Q; Harling, O K; Riley, K J; Binns, P J; Kaplan, J; Patel, H; Zamenhof, R G; Shibata, Y; Kaplan, I D; Busse, P M; Palmer, M R

2004-11-01

370

Validation of dose planning calculations for boron neutron capture therapy using cylindrical and anthropomorphic phantoms  

NASA Astrophysics Data System (ADS)

In this paper, the accuracy of dose planning calculations for boron neutron capture therapy (BNCT) of brain and head and neck cancer was studied at the FiR 1 epithermal neutron beam. A cylindrical water phantom and an anthropomorphic head phantom were applied with two beam aperture-to-surface distances (ASD). The calculations using the simulation environment for radiation application (SERA) treatment planning system were compared to neutron activation measurements with Au and Mn foils, photon dose measurements with an ionization chamber and the reference simulations with the MCNP5 code. Photon dose calculations using SERA differ from the ionization chamber measurements by 2-13% (disagreement increased along the depth in the phantom), but are in agreement with the MCNP5 calculations within 2%. The 55Mn(n,?) and 197Au(n,?) reaction rates calculated using SERA agree within 10% and 8%, respectively, with the measurements and within 5% with the MCNP5 calculations at depths >0.5 cm from the phantom surface. The 55Mn(n,?) reaction rate represents the nitrogen and boron depth dose within 1%. Discrepancy in the SERA fast neutron dose calculation (of up to 37%) is corrected if the biased fast neutron dose calculation option is not applied. Reduced voxel cell size (<=0.5 cm) improves the SERA calculation accuracy on the phantom surface. Despite the slight overestimation of the epithermal neutrons and underestimation of the thermal neutrons in the beam model, neutron calculation accuracy with the SERA system is sufficient for reliable BNCT treatment planning with the two studied treatment distances. The discrepancy between measured and calculated photon dose remains unsatisfactorily high for depths >6 cm from the phantom surface. Increasing discrepancy along the phantom depth is expected to be caused by the inaccurately determined effective point of the ionization chamber.

Koivunoro, Hanna; Seppälä, Tiina; Uusi-Simola, Jouni; Merimaa, Katja; Kotiluoto, Petri; Serén, Tom; Kortesniemi, Mika; Auterinen, Iiro; Savolainen, Sauli

2010-06-01

371

Validation of dose planning calculations for boron neutron capture therapy using cylindrical and anthropomorphic phantoms.  

PubMed

In this paper, the accuracy of dose planning calculations for boron neutron capture therapy (BNCT) of brain and head and neck cancer was studied at the FiR 1 epithermal neutron beam. A cylindrical water phantom and an anthropomorphic head phantom were applied with two beam aperture-to-surface distances (ASD). The calculations using the simulation environment for radiation application (SERA) treatment planning system were compared to neutron activation measurements with Au and Mn foils, photon dose measurements with an ionization chamber and the reference simulations with the MCNP5 code. Photon dose calculations using SERA differ from the ionization chamber measurements by 2-13% (disagreement increased along the depth in the phantom), but are in agreement with the MCNP5 calculations within 2%. The (55)Mn(n,gamma) and (197)Au(n,gamma) reaction rates calculated using SERA agree within 10% and 8%, respectively, with the measurements and within 5% with the MCNP5 calculations at depths >0.5 cm from the phantom surface. The (55)Mn(n,gamma) reaction rate represents the nitrogen and boron depth dose within 1%. Discrepancy in the SERA fast neutron dose calculation (of up to 37%) is corrected if the biased fast neutron dose calculation option is not applied. Reduced voxel cell size (neutrons and underestimation of the thermal neutrons in the beam model, neutron calculation accuracy with the SERA system is sufficient for reliable BNCT treatment planning with the two studied treatment distances. The discrepancy between measured and calculated photon dose remains unsatisfactorily high for depths >6 cm from the phantom surface. Increasing discrepancy along the phantom depth is expected to be caused by the inaccurately determined effective point of the ionization chamber. PMID:20508317

Koivunoro, Hanna; Seppälä, Tiina; Uusi-Simola, Jouni; Merimaa, Katja; Kotiluoto, Petri; Serén, Tom; Kortesniemi, Mika; Auterinen, Iiro; Savolainen, Sauli

2010-06-21

372

Boron-Containing Compounds for Liposome-Mediated Tumor Localization and Application to Neutron Capture Therapy  

SciTech Connect

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.

Professor M. Frederick Hawthorne

2005-04-07

373

Measurement of the neutron capture cross-section of 232 Th using the neutron activation technique  

Microsoft Academic Search

.  The 232Th(n,) reaction cross-section at average neutron energies of 3.7±0.3 MeV and 9.85±0.38 MeV from the 7Li(p, n) reaction has been determined for the first time using activation and off-line -ray spectrometric technique. The 232Th(n, 2n) reaction cross-section at the average neutron energy of 9.85±0.38 MeV has been also determined using the same technique.\\u000a The experimentally determined 232Th(n,) and 232Th(n,

H. Naik; P. M. Prajapati; S. V. Surayanarayana; K. C. Jagadeesan; S. V. Thakare; D. Raj; V. K. Mulik; B. S. Sivashankar; B. K. Nayak; S. C. Sharma; S. Mukherjee; Sarbjit Singh; A. Goswami; S. Ganesan; V. K. Manchanda

2011-01-01

374

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

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

Zimin, S; Allen, B J

2000-01-01

375

A review of boron neutron capture therapy (BNCT) and the design and dosimetry of a high-intensity, 24 keV, neutron beam for BNCT research.  

PubMed

This paper reviews the development of boron neutron capture therapy (BNCT) and describes the design and dosimetry of an intermediate energy neutron beam, developed at the Harwell Laboratory, principally for BNCT research. Boron neutron capture therapy is a technique for the treatment of gliomas (a fatal form of brain tumour). The technique involves preferentially attaching 10B atoms to tumour cells and irradiating them with thermal neutrons. The thermal neutron capture products of 10B are short range and highly damaging, so they kill the tumour cells, but healthy tissue is relatively undamaged. Early trials required extensive neurosurgery to exposure the tumour to the thermal neutrons used and were unsuccessful. It is thought that intermediate-energy neutrons will overcome many of the problems encountered in the early trials, because they have greater penetration prior to thermalization, so that surgery will not be required. An intermediate-energy neutron beam has been developed at the Harwell Laboratory for research into BNCT. Neutrons from the core of a high-flux nuclear reactor are filtered with a combination of iron, aluminium and sulphur. Dosimetry measurements have been made to determine the neutron and gamma-ray characteristics of this beam, and to monitor them throughout the four cycles used for BNCT research. The beam is of high intensity (approximately 2 x 10(7) neutrons cm-2 s-1, equivalent to a neutron kerma rate in water of 205 mGy h-1) and nearly monoenergetic (93% of the neutrons have energies approximately 24 keV, corresponding to 79% of the neutron kerma rate). PMID:3064858

Perks, C A; Mill, A J; Constantine, G; Harrison, K G; Gibson, J A

1988-12-01

376

Strong neutrino cooling by cycles of electron capture and ?- decay in neutron star crusts.  

PubMed

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, ?(-) 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

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

377

A capture-gated neutron calorimeter using plastic scintillators and 3He drift tubes  

SciTech Connect

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%.

Wang, Zhehui [Los Alamos National Laboratory; Morris, Christopher L [Los Alamos National Laboratory; Spaulding, Randy J [Los Alamos National Laboratory; Bacon, Jeffrey D [Los Alamos National Laboratory; Borozdin, Konstantin N [Los Alamos National Laboratory; Chung, Kiwhan [Los Alamos National Laboratory; Clark, Deborah J [Los Alamos National Laboratory; Green, Jesse A [Los Alamos National Laboratory; Greene, Steven J [Los Alamos National Laboratory; Hogan, Gary E [Los Alamos National Laboratory; Jason, Andrew [Los Alamos National Laboratory; Lisowski, Paul W [Los Alamos National Laboratory; Makela, Mark F [Los Alamos National Laboratory; Mariam, Fessaha G [Los Alamos National Laboratory; Miyadera, Haruo [Los Alamos National Laboratory; Murray, Matthew M [Los Alamos National Laboratory; Saunders, Alexander [Los Alamos National Laboratory; Wysocki, Frederick J [Los Alamos National Laboratory; Gray, Frederick E [REGIS UNIV.

2010-01-01

378

Progress towards boron neutron capture therapy at the High Flux Reactor Petten.  

PubMed

During 1988 the first positive steps were taken to proceed with the design and construction of a neutron capture therapy facility on the High Flux Reactor (HFR) at Petten. The immediate aim is to realise within a short time (summer 1989), an epithermal neutron beam for radiobiological and filter optimisation studies on one of the 10 small aperture horizontal beam tubes. The following summer, a much larger neutron beam, i.e., in cross section and neutron fluence rate, will be constructed on one of the two large beam tubes that replaced the old thermal column in 1984. This latter beam tube faces one whole side of the reactor vessel, extending from a 50 x 40 cm input aperture to a 35 x 35 cm exit hole. The radiotherapeutic facility will be housed here, with the intention to start clinical trials at the beginning of 1991. This paper describes the present status of the project and includes: a general description of the pertinent characteristics with respect to NCT of the HFR; results of the recently completed preliminary neutron metrology and computer modeling at the input end of the candidate beam tube; the structure and planning of the proposed Work Programme; and the respective direct and indirect participation and collaboration with the Netherlands Cancer Institute and the European Collaboration Group on BNCT. PMID:2268238

Moss, R L

1990-01-01

379

Europium resonance parameters from neutron capture and transmission measurements in the energy range 0.01200 eV  

E-print Network

Europium resonance parameters from neutron capture and transmission measurements in the energy e i n f o Article history: Received 6 December 2013 Accepted 31 January 2014 Keywords: Europium Transmission Capture Thermal cross section RPI Resonance parameters a b s t r a c t Europium is a good absorber

Danon, Yaron

380

Optimization of Boron Neutron Capture Therapy for the Treatment of Undifferentiated Thyroid Cancer  

SciTech Connect

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.

Dagrosa, Maria Alejandra; Thomasz, Lisa M.Sc. [Department of Radiobiology (Constituyentes Atomic Center), National Atomic Energy Commission of Argentina, Buenos Aires (Argentina); Longhino, Juan [Nuclear Reactor RA-6 (Bariloche Atomic Center), National Atomic Energy Commission of Argentina, Buenos Aires (Argentina); Perona, Marina [Department of Radiobiology (Constituyentes Atomic Center), National Atomic Energy Commission of Argentina, Buenos Aires (Argentina); Calzetta, Osvaldo; Blaumann, Herman [Nuclear Reactor RA-6 (Bariloche Atomic Center), National Atomic Energy Commission of Argentina, Buenos Aires (Argentina); Rebagliati, Raul Jimenez [Department of Chemistry (Constituyentes Atomic Center), National Atomic Energy Commission of Argentina, Buenos Aires (Argentina); Cabrini, Romulo [Department of Radiobiology (Constituyentes Atomic Center), National Atomic Energy Commission of Argentina, Buenos Aires (Argentina); Kahl, Steven [Department of Pharmaceutical Chemistry, University of California, San Francisco, CA (United States); Juvenal, Guillermo Juan [Department of Radiobiology (Constituyentes Atomic Center), National Atomic Energy Commission of Argentina, Buenos Aires (Argentina); Pisarev, Mario Alberto [Department of Radiobiology (Constituyentes Atomic Center), National Atomic Energy Commission of Argentina, Buenos Aires (Argentina); Department of Human Biochemistry, School of Medicine, University of Buenos Aires, Buenos Aires (Argentina)], E-mail: pisarev@cnea.gov.ar

2007-11-15

381

Neutron capture cross sections for the weak s process in massive stars  

SciTech Connect

Neutron capture nucleosynthesis in massive stars plays an important role in galactic chemical evolution as well as for the analysis of abundance patterns in very old metal-poor halo stars. The so-called weak s-process component, which is responsible for most of the s abundances between Fe and Sr, turned out to be very sensitive to the stellar neutron capture cross sections in this mass region and, in particular, of isotopes near the seed distribution around Fe. Activation measurements in a quasistellar neutron spectrum corresponding to a thermal energy of kT=25 keV have been carried out on {sup 58}Fe, {sup 59}Co, {sup 64}Ni, {sup 63}Cu, and {sup 65}Cu. By a series of repeated irradiations with different experimental conditions, uncertainties between 3.0% and 4.6% could be achieved, factors of 2 to 3 more accurate than previous data. Compared to previous measurements, severe discrepancies were found for {sup 63,65}Cu. The consequences of these results have been studied by detailed model calculations for convective core He burning and convective shell C burning in massive stars.

Heil, M.; Kaeppeler, F.; Uberseder, E.; Gallino, R.; Pignatari, M. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Dipartimento di Fisica Generale, Universita di Torino, Via. P. Giuria 1, I-10125 Torino (Italy)

2008-01-15

382

Monte Carlo calculations of thermal neutron capture in gadolinium: A comparison of GEANT4 and MCNP with measurements  

SciTech Connect

GEANT4 is a Monte Carlo code originally implemented for high-energy physics applications and is well known for particle transport at high energies. The capacity of GEANT4 to simulate neutron transport in the thermal energy region is not equally well known. The aim of this article is to compare MCNP, a code commonly used in low energy neutron transport calculations and GEANT4 with experimental results and select the suitable code for gadolinium neutron capture applications. To account for the thermal neutron scattering from chemically bound atoms [S({alpha},{beta})] in biological materials a comparison of thermal neutron fluence in tissue-like poly(methylmethacrylate) phantom is made with MCNP4B, GEANT4 6.0 patch1, and measurements from the neutron capture therapy (NCT) facility at the Studsvik, Sweden. The fluence measurements agreed with MCNP calculated results considering S({alpha},{beta}). The location of the thermal neutron peak calculated with MCNP without S({alpha},{beta}) and GEANT4 is shifted by about 0.5 cm towards a shallower depth and is 25%-30% lower in amplitude. Dose distribution from the gadolinium neutron capture reaction is then simulated by MCNP and compared with measured data. The simulations made by MCNP agree well with experimental results. As long as thermal neutron scattering from chemically bound atoms are not included in GEANT4 it is not suitable for NCT applications.

Enger, Shirin A.; Munck af Rosenschoeld, Per; Rezaei, Arash; Lundqvist, Hans [Division of Biomedical Radiation Sciences, Department of Oncology, Radiology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala (Sweden); Department of Radiation Physics, Lund University Hospital, SE-22185 Lund (Sweden); Division of Medical Radiation Physics, Department of Oncology-Pathology, Karolinska Institutet, SE-171 76 Stockholm (Sweden) and Studsvik Medical AB, SE-612 82 Nykoeping (Sweden); Division of Biomedical Radiation Sciences, Department of Oncology, Radiology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala (Sweden)

2006-02-15

383

A measurement of the thermal neutron capture cross section of /sup 232/Th  

SciTech Connect

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.

Jones, R.T.; Merritt, J.S.; Okazaki, A.

1986-06-01

384

Preparation of thin arsenic and radioarsenic targets for neutron capture studies  

SciTech Connect

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).

Fassbender, Michael E [Los Alamos National Laboratory

2009-01-01

385

Neutron capture cross section of unstable 63Ni: implications for stellar nucleosynthesis.  

PubMed

The 63Ni(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=5-100??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

Lederer, C; Massimi, C; Altstadt, S; Andrzejewski, J; Audouin, L; Barbagallo, M; Bécares, V; Be?vá?, 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; Krti?ka, 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

386

Neutron capture cross section of unstable 63Ni implications for stellar nucleosynthesis  

E-print Network

The $^{63}$Ni($n, \\gamma$) 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 keV to 100 keV with uncertainties around 20%. Stellar model calculations for a 25 M$_\\odot$ star show that the new data have a significant effect on the $s$-process production of $^{63}$Cu, $^{64}$Ni, and $^{64}$Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

Lederer, C; Altstadt, S; Andrzejewski, J; Audouin, L; Barbagallo, M; Becares, V; Becvar, F; Belloni, F; Berthoumieux, E; Billowes, J; Boccone, V; Bosnar, D; Brugger, M; Calviani, M; Calvino, F; Cano-Ott, D; Carrapico, C; Cerutti, F; Chiaveri, E; Chin, M; Colonna, N; Cortes, G; Cortes-Giraldo, M.A; Diakaki, M; Domingo-Pardo, C; Duran, I; Dressler, R; Dzysiuk, N; Eleftheriadis, C; Ferrari, A; Fraval, K; Ganesan, S; Garcia, A R; Giubrone, G; Gomez-Hornillos, M B; Goncalves, I F; Gonzalez-Romero, E; Griesmayer, E; Guerrero, C; Gunsing, F; Gurusamy, P; Jenkins, D G; Jericha, E; Kadi, Y; Kappeler, F; Karadimos, D; Kivel, N; Koehler, P; Kokkoris, M; Korschinek, G; Krticka, M; Kroll, J; Langer, C; Leeb, H; Leong, L S; Losito, R; Manousos, A; Marganiec, J; Martinez, 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; Tarrio, 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; 10.1103/PhysRevLett.110.022501

2013-01-01

387

Neutron capture cross section of unstable 63Ni: implications for stellar nucleosynthesis  

E-print Network

The $^{63}$Ni($n, \\gamma$) 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 keV to 100 keV with uncertainties around 20%. Stellar model calculations for a 25 M$_\\odot$ star show that the new data have a significant effect on the $s$-process production of $^{63}$Cu, $^{64}$Ni, and $^{64}$Zn in massive stars, allowing stronger constraints on the Cu yields from explosive nucleosynthesis in the subsequent supernova.

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

2013-04-11

388

Ultrananopores in Carbons by Boron-neutron Capture and Their Effect on Hydrogen Storage  

NASA Astrophysics Data System (ADS)

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.

Romanos, J.; Robertson, D.; Beckner, M.; Kraus, M.; Kuchta, B.; Firlej, L.; Pfeifer, P.

2010-03-01

389

Neutron Capture Cross Section of Unstable Ni63: Implications for Stellar Nucleosynthesis  

NASA Astrophysics Data System (ADS)

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.

Lederer, C.; Massimi, C.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bécares, V.; Be?vá?, 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.; Krti?ka, 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.; Žugec, P.

2013-01-01

390

Neutron Capture Surrogate Reaction on 75As in Inverse Kinematics Using (d,p(gamma))  

SciTech Connect

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.

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

391

Synthesis and evaluation of boron compounds for neutron capture therapy of malignant brain tumors  

SciTech Connect

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.

Soloway, A.H.; Barth, R.F.

1990-01-01

392

Boron Neutron Capture Therapy (BNCT) Dose Calculation using Geometrical Factors Spherical Interface for Glioblastoma Multiforme  

SciTech Connect

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.

Zasneda, Sabriani; Widita, Rena [Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha No. 10 Bandung, 40132 (Indonesia)

2010-06-22

393

Boron Neutron Capture Therapy (BNCT) Dose Calculation using Geometrical Factors Spherical Interface for Glioblastoma Multiforme  

NASA Astrophysics Data System (ADS)

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, ?) 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 10B/g blood.

Zasneda, Sabriani; Widita, Rena

2010-06-01

394

Description of the proton and neutron radiative capture reactions in the Gamow shell model  

NASA Astrophysics Data System (ADS)

We formulate the Gamow shell model (GSM) in coupled-channel (CC) representation for the description of proton/neutron radiative capture reactions and present the first application of this new formalism for the calculation of cross sections in mirror reactions 7Be(p ,? ) 8B and 7Li(n,? ) 8Li . The GSM-CC formalism is applied to a translationally invariant Hamiltonian with an effective finite-range two-body interaction. Reactions channels are built by GSM wave functions for the ground state 3 /2- and the first excited state 1 /2- of 7Be /7Li and the proton/neutron wave function expanded in different partial waves.

Fossez, K.; Michel, N.; P?oszajczak, M.; Jaganathen, Y.; Id Betan, R. M.

2015-03-01

395

Uranium-loaded apoferritin with antibodies attached: molecular design for uranium neutron-capture therapy.  

PubMed Central

A method is described to deliver 235U to tumors; the isotope would then be fissioned by incident neutrons, producing localized lethal radiation sufficient for therapy. Apoferritin was loaded with an average of approximately 800 238U atoms per molecule. Stability of the loaded apoferritin in solution was improved, so that only 8% loss of uranium occurred after 8 days at pH 7. Fab' antibody fragments were covalently attached to the uranium-loaded apoferritin, and the immunoreactivity of the conjugate was 92% of that for antibody alone. Such bio-uranium constructions should provide significant advantages over boronated antibodies to meet the requirements for clinical neutron-capture therapy. Images PMID:1438316

Hainfeld, J F

1992-01-01

396

Description of the proton and neutron radiative capture reactions in the Gamow shell model  

E-print Network

We formulate the Gamow shell model (GSM) in coupled-channel (CC) representation for the description of proton/neutron radiative capture reactions and present the first application of this new formalism for the calculation of cross-sections in mirror reactions 7Be(p,gamma)8B and 7Li(n,gamma)8Li. The GSM-CC formalism is applied to a translationally-invariant Hamiltonian with an effective finite-range two-body interaction. Reactions channels are built by GSM wave functions for the ground state 3/2- and the first excited state 1/2- of 7Be/7Li and the proton/neutron wave function expanded in different partial waves.

K. Fossez; N. Michel; M. P?oszajczak; Y. Jaganathen; R. M. Id Betan

2015-02-10

397

Description of the proton and neutron radiative capture reactions in the Gamow shell model  

E-print Network

We formulate the Gamow shell model (GSM) in coupled-channel (CC) representation for the description of proton/neutron radiative capture reactions and present the first application of this new formalism for the calculation of cross-sections in mirror reactions 7Be(p,gamma)8B and 7Li(n,gamma)8Li. The GSM-CC formalism is applied to a translationally-invariant Hamiltonian with an effective finite-range two-body interaction. Reactions channels are built by GSM wave functions for the ground state 3/2- and the first excited state 1/2- of 7Be/7Li and the proton/neutron wave function expanded in different partial waves.

Fossez, K; P?oszajczak, M; Jaganathen, Y

2015-01-01

398

Comparison of Snyder Head Phantom Models Used for Neutron Capture Therapy Benchmark Monte Carlo Dosimetry Calculations  

NASA Astrophysics Data System (ADS)

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.

Goorley, T.; Kiger, W. S.; Zamenhof, R.

399

Thermal neutron capture cross section of gadolinium by pile-oscillation measurements in MINERVE  

SciTech Connect

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)

Leconte, P.; Di-Salvo, J.; Antony, M.; Pepino, A. [CEA, DEN, DER, Cadarache, F-13108 Saint-Paul-Lez-Durance (France); Hentati, A. [International School in Nuclear Engineering, Cadarache, F-13108 Saint-Paul-Lez-Durance (France)

2012-07-01

400

Tomographic image of prompt gamma ray from boron neutron capture therapy: A Monte Carlo simulation study  

SciTech Connect

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.

Yoon, Do-Kun; Jung, Joo-Young; Suk Suh, Tae, E-mail: suhsanta@catholic.ac.kr [Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, Catholic University of Korea, Seoul 505 (Korea, Republic of); Jo Hong, Key [Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University, 300 Pasteur Drive, Stanford, California 94305 (United States)

2014-02-24

401

Combination of the vascular targeting agent ZD6126 with boron neutron capture therapy  

Microsoft Academic Search

Purpose: The aim of this study was to evaluate the antitumor efficacy of the vascular targeting agent ZD6126 (N-acetylcochinol-O-phosphate) in the rodent squamous cell carcinoma (SCC) VII carcinoma model, in combination with boron neutron capture therapy (BNCT). Methods and materials: Sodium borocaptate-¹°B (BSH, 125 mg\\/kg, i.p.) or l-p-boronophenylalanine-¹°B (BPA, 250 mg\\/kg, i.p.) was injected into SCC VII tumor-bearing mice, and

Shin-ichiro. Masunaga; Yoshinori Sakurai; Minoru Suzuki; Kenji Nagata; Akira Maruhashi; Yuko Kinash; Koji Ono

2004-01-01

402

Drug delivery system design and development for boron neutron capture therapy on cancer treatment.  

PubMed

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

Sherlock Huang, Lin-Chiang; Hsieh, Wen-Yuan; Chen, Jiun-Yu; Huang, Su-Chin; Chen, Jen-Kun; Hsu, Ming-Hua

2014-06-01

403

Dose estimation for internal organs during boron neutron capture therapy for body-trunk tumors.  

PubMed

Radiation doses during boron neutron capture therapy for body-trunk tumors were estimated for various internal organs, using data from patients treated at Kyoto University Research Reactor Institute. Dose-volume histograms were constructed for tissues of the lung, liver, kidney, pancreas, and bowel. For pleural mesothelioma, the target total dose to the normal lung tissues on the diseased side is 5Gy-Eq in average for the whole lung. It was confirmed that the dose to the liver should be carefully considered in cases of right lung disease. PMID:24679832

Sakurai, Y; Tanaka, H; Suzuki, M; Masunaga, S; Kinashi, Y; Kondo, N; Ono, K; Maruhashi, A

2014-06-01

404

Boron neutron capture therapy as new treatment for clear cell sarcoma: trial on different animal model.  

PubMed

Clear cell sarcoma (CCS) is a rare malignant tumor with a poor prognosis. In our previous study, the tumor disappeared under boron neutron capture therapy (BNCT) on subcutaneously-transplanted CCS-bearing animals. In the present study, the tumor disappeared under this therapy on model mice intramuscularly implanted with three different human CCS cells. BNCT led to the suppression of tumor-growth in each of the different model mice, suggesting its potentiality as an alternative to, or integrative option for, the treatment of CCS. PMID:24389062

Andoh, Tooru; Fujimoto, Takuya; Sudo, Tamotsu; Suzuki, Minoru; Sakurai, Yoshinori; Sakuma, Toshiko; Moritake, Hiroshi; Sugimoto, Tohru; Takeuchi, Tamotsu; Sonobe, Hiroshi; Epstein, Alan L; Fukumori, Yoshinobu; Ono, Koji; Ichikawa, Hideki

2014-06-01

405

Measurement of the thermal neutron capture cross section and the resonance integral of radioactive Hf182  

NASA Astrophysics Data System (ADS)

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 ?-ray spectroscopy of Hf183. High values for the thermal (kT=25 meV) cross section ?0=133±10 b and for the resonance integral I0=5850±660 b were found. Additionally, the absolute intensities of the main ?-ray transitions in the decay of Hf182 have been considerably improved.

Vockenhuber, C.; Bichler, M.; Wallner, A.; Kutschera, W.; Dillmann, I.; Käppeler, F.

2008-04-01