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1

Neutron radiative capture  

SciTech Connect

This book presents a description of radiative capture processes at both low and high neutron energies; explains how calculations of the cross sections and spectra can be made and illustrates the techniques of capture measurements to form a coherent picture of the theory and applications of neutron capture. Contents include: Theory of Slow Neutron Radiative Capture: Introduction. Statistical theory of radiative capture. Neutron capture reaction mechanisms. Systematic properties of radiative neutron capture. Applications to stellar nucleosynthesis. Fast Neutron Radiative Capture: Direct and semidirect capture reactions. The compound nucleus model. Experimental results. Methods for calculating Neutron Cross Sections and Gamma-Ray Energy Spectra: Scope. Statistical model calculations. Expressions for El photon strengths. Giant dipole resonance systematics. Summary. Measurement Techniques for Radiative Neutron Capture: Introduction. Capture event detection. Analysis of measuarements. Neutron capture processes in fission reactors: Introduction. Capture in fertile and fissile nuclei. Capture in structural, coolout and shielding materials. Capture in fission product nuclei. The production of higher actinides.

Chrien, R.E.

1983-01-01

2

The slow-neutron capture process in low-metallicity asymptotic giant branch stars  

NASA Astrophysics Data System (ADS)

Elements heavier than iron are produced in asymptotic giant branch (AGB) stars via the slow neutron capture process (s process). Recent observations of s-process-enriched Carbon Enhanced Metal-Poor (CEMP) stars have provided an unprecedented wealth of observational constraints on the operation of the s-process in low-metallicity AGB stars. We present new preliminary full network calculations of low-metallicity AGB stars, including a comparison to the composition of a few s-process rich CEMP stars. We also discuss the possibility of using halo planetary nebulae as further probes of low-metallicity AGB nucleosynthesis.

Karakas, Amanda I.; Lugaro, Maria; Campbell, Simon W.

2010-03-01

3

REVIEWS OF TOPICAL PROBLEMS: The theory of nucleosynthesis in stars: the slow neutron capture process  

NASA Astrophysics Data System (ADS)

The theory of the s process of nucleosynthesis has received considerable development during recent years, mainly as the result of more detailed physical and mathematical treatments and also as a result of the accumulation of new observational data on stellar evolution and the abundance of the elements in the solar system, and accumulation of experimental data on neutron-capture cross sections. The exact solution of the s process equations obtained recently by Newman (1978) is discussed. It confirms the correctness of the initial s process theory (Clayton, Fowler, Hull, and Zimmerman, 1961). At the same time for small neutron exposures the exact and initial solutions differ. The influence of branching of the s-process due to competition between ? decay and neutron capture is analyzed; it is noted that at a temperature ~3·108 K and a density of free neutrons 1.6·107 cm-3 the s process theory is in good agreement with observational data on the yields of the various nuclides. Models are discussed for the pulsed neutron s process, which leads to formation of heavy elements in the interior of a star as the result of periodic flares of the helium shell and subsequent remixing of the material.

Chechev, Valerii P.; Kramarovski?, Ya M.

1981-07-01

4

Possibility of a crossed-beam experiment involving slow-neutron capture by unstable nuclei - ``rapid-process tron''  

NASA Astrophysics Data System (ADS)

The possibility of a crossed beam facility of slow neutrons capturing unstable nuclei is examined in connection with the Japanese Hadron Project. With a pulsed proton beam of 50 Hz repetition and with a 100 ?A average beam current, one obtains a spallation neutron source of 2.4 × 108 thermal neutrons/cm3/spill over a 60 cm length with a 3 ms average duration time by using a D2O moderator. By confining radioactive nuclei of 109 ions in a beam circulation ring of 0.3 MHz revolution frequency, so that nuclei pass through the neutron source, one obtains a collision luminosity of 3.9 × 1024/cm2/s. A new research domain aimed at studying rapid processes in nuclear genetics in a laboratory will be created.

Yamazaki, T.; Katayama, I.; Uwamino, Y.

1993-02-01

5

Possibility of a crossed-beam experiment involving slow-neutron capture by unstable nuclei rapid-process-tron  

NASA Astrophysics Data System (ADS)

The possibility of a crossed beam facility of slow neutrons crossed with unstable nuclei is examined in connection with the Japanese Hadron Project. With a pulsed proton beam of 50 Hz repetition with a 100 micro-Amp average beam current, one obtains a spallation neutron source of 2.4(10)(exp 8) thermal neutrons/cu cm/spill over a 60 cm length with a 3 msec average duration time by using a D2O moderator. By confining radioactive nuclei of 10(exp 9) ions in a beam circulation ring of 0.3 MHz revolution frequency, so that they pass through the neutron source, one obtains a collision luminosity of 3.9(10)(exp 24)/sq cm/s. A new research domain aimed at studying rapid processes in nuclear genetics will be created.

Yamazaki, T.; Katayama, I.; Uwamino, Y.

1992-07-01

6

Iodine neutron capture therapy  

Microsoft Academic Search

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

Kazi Fariduddin Ahmed

1999-01-01

7

Neutron capture therapies  

SciTech Connect

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

1999-11-02

8

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

9

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

10

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

11

Neutron Capture from ^87Sr  

NASA Astrophysics Data System (ADS)

The neutron-capture resonances of the reaction ^87Sr(n,?)^88Sr are significant to nuclear astrophysics to estimate the neutron density during the s process, whose path is split by the branching nucleus ^85Kr, and for a possible use of the ^87Rb-^87Sr chronometric pair to measure the age of our Galaxy. In addition, the ? rays of the product nucleus ^88Sr are of importance to nuclear structure and the study of the pygmy resonance observed earlier in (,') measurements. We report results from a neutron-capture experiment on ^87Sr carried out with the 4? BaF2 array, DANCE, at LANL. Spin values of neutron resonances have been deduced using the multiplicity and angular distributions of the cascade ? rays following the neutron capture.

Rusev, G.; Raut, R.; Tonchev, A. P.; Tornow, W.; Baramsai, B.; Kelley, J. H.; Mitchell, G.; Bredeweg, T.; Couture, A.; Jandel, M.; O'Donnell, J.; Rundberg, R.; Ullmann, J. L.; Chyzh, A.; Kwan, E.

2011-10-01

12

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

13

Glioblastoma: Boron Neutron Capture Therapy  

Microsoft Academic Search

\\u000a Boron neutron capture therapy (BNCT) is a unique method that can deliver tumor-cell-selective high-linear energy transfer\\u000a (LET) particle radiotherapy to an extended target area encompassing a microscopic invasion while avoiding radiation damage\\u000a to the surrounding normal brain tissue. The process of BNCT is based on the nuclear interaction of 10B with thermal neutrons with the release of high LET ?

Tetsuya Yamamoto; Kei Nakai; Hiroaki Kumada

14

Surrogate reactions for neutron capture with radioactive ion beams  

NASA Astrophysics Data System (ADS)

Neutron capture reactions are responsible for most of the elements heavier than iron, through either the slow or rapid processes of nucleosynthesis. The r process in particular proceeds through very short-lived nuclei on which neutron capture reaction measurements will never be possible. Knowledge of neutron capture cross sections on short-lived nuclei is also important for applications such as nuclear energy, nuclear forensics, and stockpile stewardship science. When the level density at the neutron separation energy is relatively low, for example near closed neutron shells, direct neutron capture often dominates and direct neutron transfer reactions can provide the spectroscopic information needed to calculate the direct capture. However, when the level density is higher, a compound nucleus is formed and statistical mechanisms dominate the decay. While the formation of the compound nucleus can be calculated with optical models, modeling of the decay is less robust. Because of the importance of neutron capture on nuclei away from stability, there have been efforts to validate surrogate reactions for neutron capture that exploit the availability of beams of radioactive nuclei that interact with light targets where reaction products are measured in coincidence with gamma radiation. This talk would summarize efforts to validate a surrogate for neutron capture and the techniques being developed to measure these reactions with beams of radioactive ions.

Cizewski, Jolie A.

2012-10-01

15

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

Microsoft Academic Search

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

Ronald V. Dorn

1994-01-01

16

Boron neutron capture therapy for malignant gliomas.  

PubMed

Boron neutron capture therapy (BNCT) represents a promising modality for a relatively selective radiation dose delivery to the tumour tissue. Boron-10 nuclei capture slow 'thermal' neutrons preferentially and, upon capture, promptly undergo 10B(n,alpha)7Li reaction. The ionization tracks of energetic and heavy lithium and helium ions resulting from this reaction are only about one cell diameter in length (approximately 14 microm). Because of their high linear energy transfer (LET) these ions have a high relative biological effectiveness (RBE) for controlling tumour growth. The key to effective BNCT of tumours, such as glioblastoma multiforme (GBM), is the preferential accumulation of boron-10 in the tumour, including the infiltrating GBM cells, as compared with that in the vital structures of the normal brain. Provided that a sufficiently high tumour boron-10 concentration (approximately 10(9) boron-10 atoms/cell) and an adequate thermal neutron fluence (approximately 10(12) neutrons/cm2) are achieved, it is the ratio of the boron-10 concentration in tumour cells to that in the normal brain cells that will largely determine the therapeutic gain of BNCT. PMID:10711581

Diaz, A Z; Coderre, J A; Chanana, A D; Ma, R

2000-02-01

17

[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

18

Neutron capture cross section of ²¹Am  

Microsoft Academic Search

The neutron capture cross section of ²¹Am 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

M. Jandel; T. A. Bredeweg; E. M. Bond; M. B. Chadwick; R. R. Clement; A. Couture; J. M. ODonnell; R. C. Haight; T. Kawano; R. Reifarth; R. S. Rundberg; J. L. Ullmann; D. J. Vieira; J. B. Wilhelmy; J. M. Wouters; U. Agvaanluvsan; W. E. Parker; C. Y. Wu; J. A. Becker

2008-01-01

19

Neutron capture cross section of Am241  

Microsoft Academic Search

The neutron capture cross section of Am241 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

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

2008-01-01

20

Probing strongly coupled chameleons with slow neutrons  

NASA Astrophysics Data System (ADS)

We consider different methods to probe the chameleon scalar field with slow neutrons. Chameleons modify the potential of bouncing neutrons over a flat mirror in the terrestrial gravitational field. This induces a shift in the energy levels of the neutrons which could be detected in current experiments like GRANIT. Chameleons between parallel plates have a field profile which is bubblelike and which would modify the phase of neutrons in interferometric experiments. We show that this new method of detection is competitive with the bouncing neutron one, hopefully providing an efficient probe of chameleons when strongly coupled to matter.

Brax, Philippe; Pignol, Guillaume; Roulier, Damien

2013-10-01

21

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

22

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

23

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

24

Halo Effect on Direct Neutron Capture Process  

NASA Astrophysics Data System (ADS)

We calculate the capture cross sections of the 10Be(n,gamma) 11Be reaction by means of the asymptotic normalization coefficient method and demonstrate the halo effects on the capture cross sections for the direct radiative neutron capture where a p-, s- or d-wave neutron is captured into an s-orbit or p-orbit in 11Be by emitting an E1 gamma-ray, respectively. The result shows that the enormous enhancement of the capture cross section is just due to the large overlap of the incident neutron wave with the extended tail of the halo, which is clearly illustrated by the reduced transition amplitude function.

Liu, Zu-Hua; Zhou, Hong-Yu

2004-01-01

25

Thermal neutron capture in silicon  

SciTech Connect

The prompt gamma-rays from thermal nuteron capture in {sup 28,29,30}Si have been studied and the radiative capture cross sections determined as 207{plus minus}4, 120{plus minus}3 and 107{plus minus}2 mb, respectively. There has been a marked increase in the number of transitions observed in {sup 29}Si and a complete decay scheme for this nucleus is presented. Two primary {ital E}2 transitions in {sup 29}Si have been observed and their partial cross sections are compared with the prediction of the direct capture formalism. The measured neutron separation energies are {ital S}{sub {ital n}}({sup 29}Si)=8473.61{plus minus}0.04 keV, {ital S}{sub {ital n}}({sup 30}Si)=10 609.21{plus minus}0.04 keV, and {ital S}{sub {ital n}}({sup 31}Si)=6587.32{plus minus}0.20 keV.

Islam, M.A.; Kennett, T.J.; Prestwich, W.V. (Department of Physics, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (CA))

1990-03-01

26

Improved neutron sources for neutron capture enhanced fast neutron therapy  

SciTech Connect

Fast neutron radiotherapy (FNT) can be combined with boron neutron capture therapy (BNCT). The selective incremental absorbed dose in the target volume that is thus obtained may be sufficient to produce a significant improvement in tumor control probability in some cases. Potential applications include certain non-small-cell lung tumors; head and neck tumors; prostate tumors; and possibly also glioblastoma multiform, an extremely refractory type of primary brain tumor. A class of modified neutron production targets has been developed to provide improved performance of the cyclotron-based clinical FNT facility at the University of Washington (UW) Medical Center for applications involving BNCT-enhanced FNT. The new targets produce neutron beams that feature essentially the same fast neutron physical depth-dose performance as the current UW system but with an increased fraction of BNCT enhancement.

Nigg, D.W.; Wemple, C.A.; Risler, R.; Hartwell, J.K.; Harker, Y.D.; Laramore, G.E.

2000-07-01

27

Neutron capture measurements on radioactive 93 Zr  

Microsoft Academic Search

Neutron capture measurements made on a sample of fission-product zirconium containing 20%93Zr(t1\\/2=1.5×106a) at the Oak Ridge Electron Linear Accelerator time-of-flight facility resulted in the identification of 138 resonance peaks for the93Zr isotope at neutron energies up to 21.5 keV. Average capture cross sections from 20 to 300 keV were derived by subtracting neutron capture yields of the stable zirconium isotopes90,

R. L. Macklin

1985-01-01

28

Neutron capture experiments with 4? DANCE Calorimeter  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

29

The capture of slow antiprotons by noble gas atoms  

NASA Astrophysics Data System (ADS)

The capture of slow antiprotons (impact energies less than 1.0 au) by the noble gases krypton and xenon is studied following the paper of Briggs at al, where the transient collision complex is treated as a diatomic molecule with the positively-charged atomic ion and antiproton as `nuclei'. Estimates of the population of long-lived `circular' states suggest that the probability of capture of antiprotons into such states is negligible. The capture cross sections for Kr and Xe are two orders of magnitude smaller than for He in agreement with experimental data.

Briggs, J. S.; Jakimovski, D.; Solov'ev, E. A.

2005-10-01

30

Research needs for neutron capture therapy.  

National Technical Information Service (NTIS)

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 Institut...

1995-01-01

31

Neutron-capture resonances for 82Se  

NASA Astrophysics Data System (ADS)

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

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

1982-09-01

32

Neutron capture cross section of ^243Am  

NASA Astrophysics Data System (ADS)

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

Jandel, M.

2009-10-01

33

Neutron capture origin for the heavy elements  

NASA Astrophysics Data System (ADS)

Most naturally occurring elements were evidently synthesized in the interiors of stars, and, in particular, most of the heavy ones via neutron capture processes. We present here an introductory review on the stellar alchemy by neutrons. In due course, we attempt to cover the very basics through the latest developments of theoretical studies of the rapid (r-) process.

Takahashi, Kohji

1995-03-01

34

Direct-Semidirect Thermal Neutron Capture Calculations  

SciTech Connect

A method for computing direct-semidirect (DSD) neutron radiative capture is presented and applied to thermal neutron capture on {sup 19}F, {sup 27}Al, {sup 28,29.30}Si, {sup 35,37}Cl, {sup 39,41}K, {sup 56}Fe, and {sup 238}U, in support of data evaluation effort at the O.R.N.L. The DSD method includes both direct and semidirect capture; the latter is a core-polarization term in which the giant dipole resonance is formed. We study the effects of a commonly used ''density'' approximation to the EM operator and find it to be unsatisfactory for the nuclei considered here. We also study the magnitude of semidirect capture relative to the pure direct capture. Furthermore, we compare our results with those obtained from another direct capture code (Tedca [17]). We also compare our results with those obtained from analytical expression for external capture derived by Lane and Lynn [3], and its extension to include internal capture [7]. To estimate the effect of nuclear deformation on direct capture, we computed direct thermal capture on {sup 238}U with and without imposition of spherical symmetry. Direct capture for a spherically symmetric {sup 238}U was approximately 6 mb, while a quadrupole deformation of 0.215 on the shape of {sup 238}U lowers this cross section down to approximately 2 mb. This result suggests that effects of nuclear deformation on direct capture warrant a further study. We also find out that contribution to the direct capture on {sup 238}U from the nuclear interior significantly cancels that coming from the exterior region, and hence both contributions must be taken into account. We reproduced a well known discrepancy between the computed and observed branching ratios in {sup 56}Fe(n,{gamma}). This will lead us to revisit the concept of doorway states in the particle-hole model.

Arbanas, G; Dietrich, F S; Kerman, A K

2005-12-20

35

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

36

Neutron capture measurements on radioactive Zr-93  

NASA Astrophysics Data System (ADS)

Neutron capture measurements made on a sample of fission-product zirconium containing 20 percent Zr-93 (half-life = 1.5 million years) are reported. The measurements resulted in the identification of 138 resonance peaks for the Zr-93 isotope at neutron energies up to 21.5 keV. The study probably satisfies the formal requests (IAEA, 1983) for better than 20 percent and better than 30 percent accuracy. All but one of the 138 resonances parameterized were previously unknown. Average capture cross sections up to 300 keV could be compared only to earlier theoretical calculations.

Macklin, R. L.

1985-10-01

37

Neutron capture measurements on radioactive Zr93  

Microsoft Academic Search

Neutron capture measurements made on a sample of fission-product zirconium containing 20 percent Zr-93 (half-life = 1.5 million years) are reported. The measurements resulted in the identification of 138 resonance peaks for the Zr-93 isotope at neutron energies up to 21.5 keV. The study probably satisfies the formal requests (IAEA, 1983) for better than 20 percent and better than 30

R. L. Macklin

1985-01-01

38

Neutron capture cross section of Am241  

NASA Astrophysics Data System (ADS)

The neutron capture cross section of Am241 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 En<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. ?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.; Agvaanluvsan, U.; Parker, W. E.; Wu, C. Y.; Becker, J. A.

2008-09-01

39

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

40

Neutron transmission and capture of 241Am  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

41

Review of the fundamentals of the neutron-capture reaction  

SciTech Connect

Fifty years of research into the nature of the radiative capture reaction mechanisms is briefly summarized. A variety of such mechanisms is exploited to explain neutron capture over nine decades of neutron energy.

Chrien, R.E.

1982-01-01

42

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

43

Research in boron neutron capture synovectomy  

NASA Astrophysics Data System (ADS)

Boron Neutron Capture Synovectomy (BNCS) is a novel application of the 10B(n, (alpha) )7Li reaction for the treatment of Rheumatoid Arthritis. This potential treatment modality is in its developmental stages; in this paper results of research in two aspects of BNCS are presented. First, quantification of 10B-uptake in samples of human arthritic tissue by Prompt Gamma Neutron Activation Analysis is presented. 10B concentrations from 1625 to 2726 ppm are readily achieved. Second, ideal neutron beam studies have been undertaken and indicate that neutrons from thermal energies to 1 keV are useful for BNCS. This information is of use in designing practical therapy beams should this treatment modality be realized.

Binello, E.; Shortkroff, S.; Jones, A.; Viveiros, C.; Ly, A.; Sledge, C. B.; Davison, A.; Shefer, Ruth E.; Yanch, Jacquelyn C.

1997-02-01

44

Design of multidirectional neutron beams for boron neutron capture synovectomy  

SciTech Connect

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

Gierga, D.P.; Yanch, J.C. [Massachusetts Institute of Technology, Cambridge, MA (United States); Shefer, R.E. [Newton Scientific, Inc., Cambridge, MA (United States)

1997-12-01

45

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

46

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

47

Boron neutron capture therapy research at the MIT research reactor  

Microsoft Academic Search

The concept of neutron capture cancer therapy, originally suggested by Locher (l), is relatively straightforward. A compound containing a suitable neutron capture agent, e.g. B, is introduced into the patient. The compound must have been developed to selectively concentrate in tumor. Then the tumor and surrounding tissue are irradiated with neutrons. Neutron induced B(n,?) Li reactions, with a positive Q

O. K. Harling

1994-01-01

48

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

49

Accelerator based epithermal neutron source for neutron capture therapy  

SciTech Connect

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

Brugger, R.; Kunze, J.

1991-05-01

50

Ligand liposomes and boron neutron capture therapy  

Microsoft Academic Search

Summary  Boron neutron capture therapy (BNCT) has been used both experimentally and clinically for the treatment of gliomas and melanomas,\\u000a with varying results. However, the therapeutic effects on micro-invasive tumor cells are not clear. The two drugs that have\\u000a been used clinically, p-boronophenylalanine, (BPA), and the sulfhydryl borane, (BSH), seem to be taken up preferentially in\\u000a solid tumor areas but it

Jörgen Carlsson; Erika Bohl Kullberg; Jacek Capala; Stefan Sjöberg; Katarina Edwards; Lars Gedda

2003-01-01

51

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

52

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

53

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

Koehler, Paul Edward [ORNL; Bredeweg, t a [Los Alamos National Laboratory (LANL); Guber, Klaus H [ORNL; Harvey, John A [ORNL; O'Donnell, J. M. [Los Alamos National Laboratory (LANL); Reifarth, R. [Los Alamos National Laboratory (LANL); Rundberg, R. S. [Los Alamos National Laboratory (LANL); Ullmann, J. L. [Los Alamos National Laboratory (LANL); Vieira, D. J. [Los Alamos National Laboratory (LANL); Wiarda, Dorothea [ORNL; Wouters, J. M. [Los Alamos National Laboratory (LANL)

2009-01-01

54

Neutron tube design study for boron neutron capture therapy application  

SciTech Connect

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

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

1999-05-06

55

How Accurately Can We Calculate Neutrons Slowing Down In Water ?  

Microsoft Academic Search

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

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

2006-01-01

56

Neutron capture cross sections for AFCI at DANCE  

NASA Astrophysics Data System (ADS)

The Detector for Advanced Neutron Capture Experiments (DANCE) is a 160-element 4? barium fluoride array designed to study neutron capture on small quantities of radioactive material. It is located on a 20 meter neutron flight path, which views an ``upper tier'' water moderator at the Manuel J. Lujan Jr. Neutron Scattering Center at the Los Alamos Neutron Science Center (LANSCE). A number of radioactive isotopes under investigation were motivated by the Advanced Fuel Cycle Initiative (AFCI). During the talk the detector will be described, and first results for the neutron capture cross section experiment on ^240,242Pu will be presented.

Reifarth, Rene

2006-04-01

57

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

58

Stellar Neutron Capture on Neon Isotopes  

SciTech Connect

The stellar (n,{gamma}) cross sections of the Ne isotopes are important for a number of astrophysical quests, i.e., for the interpretation of abundance patterns in presolar material or with respect to the s-process neutron balance in red giant stars. This paper presents resonance studies of experimental data in the keV range, which had not been fully analyzed before. The analyses were carried out with the R-matrix code SAMMY including the consistent treatment of possible interferences in the resonant part. With these results the resonant part of the neon cross sections could be determined. If the component due to direct radiative capture is normalized at thermal neutron energies, one finds that the stellar rates had been grossly overestimated.

Heil, M.; Plag, R.; Juseviciute, A.; Kaeppeler, F. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Gallino, R. [Istituto di Fisica Generale, Universita di Torino, Via P. Giuria 1, I-10125 Turin (Italy); Sezione INFN di Torino, Via P. Giuria 1, I-10125 Turin (Italy); Mengoni, A. [CERN, CH-1211 Geneva 23 (Switzerland)

2005-05-24

59

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

NASA Astrophysics Data System (ADS)

We consider the astrophysical reaction rates for radiative neutron capture reactions (n,?) 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 (?,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.

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

2012-07-01

60

Liposomal boron delivery for neutron capture therapy.  

PubMed

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

Nakamura, Hiroyuki

2009-01-01

61

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

62

NSTAR—A capture gated plastic neutron detector  

Microsoft Academic Search

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

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

2011-01-01

63

Neutronic design of a fission converter-based epithermal neutron beam for neutron capture therapy  

Microsoft Academic Search

To meet the needs for neutron capture theory (NCT) irradiations, a high-intensity, high-quality fusion converter-based epithermal neutron beam has been designed for the MITR-II research reactor. This epithermal neutron beam, capable of delivering treatments in a few minutes with negligible background contamination from fast neutrons and photons, will be installed in the present thermal column and hohlraum of the 5-MW

W. S. Kiger; S. Sakamoto; O. K. Harling

1999-01-01

64

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

65

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

66

Neutron Capture Experiments Using the DANCE Array at Los Alamos  

NASA Astrophysics Data System (ADS)

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 BaF2 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.; Mitchell, G. E.; Baramsai, B.; Chyzh, A.; Walker, C.; Agvaanluvsan, U.; Becker, J. A.; Parker, W.; Sleaford, B.; Wu, C. Y.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.; Krti?ka, M.; Be?vá?, F.

2009-03-01

67

SCATTERING OF SLOW NEUTRONS BY A LIQUID  

Microsoft Academic Search

The differential cross section for coherent scattering of thermal ; neutrons by a liquid is given in general by the Fourier transform of a time-; displaced radial density function. It is suggested that, to an adequate degree ; of approximation, this time-displaced function can be expressed as a convolution ; of the ordinary radial density function with a self-diffusion function

George Vineyard

1958-01-01

68

The Detector for Advanced Neutron Capture Experiments at LANSCE  

NASA Astrophysics Data System (ADS)

The Detector for Advanced Neutron Capture Experiments (DANCE) is a 159-element 4? barium fluoride array designed to study neutron capture on small quantities of radioactive material. It is being built on a 20m 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. Monte Carlo calculations have suggested ways to minimize backgrounds due to neutron scattering events. Preliminary data on an 8 mg sample of 234U and a 0.5 mg sample of 151Sm have been taken using C6D6 detectors.

Ullmann, J. L.; Haight, R. C.; Hunt, L.; Seabury, E.; Rundberg, R. S.; Wilhelmy, J. B.; Fowler, M. M.; Strottman, D. D.; Kaeppeler, F.; Reifarth, R.; Heil, M.; Chamberlin, E. P.

2002-12-01

69

The Detector for Advanced Neutron Capture Experiments at LANSCE  

NASA Astrophysics Data System (ADS)

The Detector for Advanced Neutron Capture Experiments (DANCE) is a 159-element 4? 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.; Kaeppeler, F.; Heil, M.; Chamberlin, E. P.

2003-08-01

70

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

71

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

72

Californium-252 Neutron Capture and Decay Methods for Elemental Analysis.  

National Technical Information Service (NTIS)

The feasibility of using a Cf-252 neutron source in conjunction with a capture and/or decay gamma ray method for elemental analysis on lunar or planetary missions was tested. The general problems of using a Cf-252 neutron source for both decay and capture...

1972-01-01

73

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

74

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

75

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

76

THE SCATTERING OF SLOW NEUTRONS BY POLAR LIQUIDS (thesis)  

Microsoft Academic Search

A quasi-crystalline model of polar liquids for the analysis of slow-; neutron scattering is proposed. Effects of the macroscopic medium are considered ; in terms of specific potentials that hinder molecular translations and rotations. ; By smearing the neighboring molecules over a spherical distribution and choosing ; a two-particle interaction that includes dipole-dipole forces, an effective ; potential for the

Yip

1962-01-01

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  

NASA Astrophysics Data System (ADS)

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. We 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.

2011-06-01

79

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

80

Correlated Double Electron Capture in Slow, Highly Charged Ion-Atom Collisions.  

National Technical Information Service (NTIS)

Recent measurements of autoionization electrons produced in slow, highly charged ion-atom collisions are reviewed. Mechanisms for double electron capture into equivalent and nonequivalent configurations are analyzed by comparing the probabilities for the ...

N. Stolterfoht C. C. Havener R. A. Phaneuf J. K. Swenson S. M. Shafroth

1986-01-01

81

Boron Neutron Capture Therapy: Brain Tumor Treatment Evaluation Program.  

National Technical Information Service (NTIS)

The United States (US) Department of Energy (DOE) recently initiated a focused, multidisciplined program to evaluate Boron Neutron Capture Therapy (BNCT) for the treatment of brain tumors. The program, centered at the DOE Idaho National Engineering Labora...

M. L. Griebenow R. V. Dorn P. R. Gavin J. H. Spickard

1988-01-01

82

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

83

Neutron-Capture gamma Rays from Various Elements  

Microsoft Academic Search

Neutron-capture gamma-ray spectra have been measured in the energy range 0.3 to 3 Mev by means of a two-crystal Compton scintillation spectrometer. The efficiency of the instrument as a function of energy was determined experimentally. The uniqueness of the 2.23-Mev gamma ray following capture of a neutron by hydrogen has been confirmed, and this gamma ray was used as a

T. H. Braid

1956-01-01

84

Stellar neutron capture cross sections of the tin isotopes  

Microsoft Academic Search

The neutron capture cross sections of 114Sn, 115Sn, 116Sn, 117Sn, 118Sn, and 120Sn 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 using a pulsed proton beam. Capture events were registered with the Karlsruhe 4pi barium fluoride detector. The experiment was complicated

K. Wisshak; F. Voss; Ch. Theis; F. Kaeppeler; K. Guber; L. Kazakov; N. Kornilov; G. Reffo

1996-01-01

85

Prompt gamma rays from thermal-neutron capture  

Microsoft Academic Search

A catalog of ..gamma..-rays emitted following thermal-neutron capture in natural elements is presented. In Table I, ..gamma..-rays are arranged in order of increasing energy. Each line contains the ..gamma..-ray energy, intensity, element identification, thermal-neutron radiative-capture cross section, and the energies and intensities of two of the more abundant ..gamma..-rays associated with that element. In Table II, ..gamma..-rays are arranged by

M. A. Lone; R. A. Leavitt; D. A. Harrison

1981-01-01

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

Neutron Capture Cross Sections: From Theory to Experiments and Back  

SciTech Connect

The method for an experimental determination of the stellar enhancement factor for the cross section of the 151Sm(n,{gamma}) reaction process is proposed. This study offered the pretext for an excursus on the interconnections between capture and dissociation reactions and the interplay between theory and experiments in the determination of neutron capture cross sections.

Mengoni, A. [CERN, CH-1211 Geneva 23 (Switzerland); ENEA, Via Don Fiammelli, 2 - 40129 Bologna (Italy)

2005-05-24

89

Thermal Neutron Capture Cross Sections of The Palladium Isotopes.  

National Technical Information Service (NTIS)

We have measured precise thermal neutron capture (gamma)-ray cross sections (sigma)(sub (gamma)) for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature a...

R. B. Firestone M. Krticka D. P. McNabb B. Sleaford U. Agvaanluvsan T. Belgya Z. Revay

2005-01-01

90

Imaging and profiling of absorbed dose in neutron capture therapy  

Microsoft Academic Search

Imaging and profiling of the absorbed dose in tissue-equivalent gel phantoms exposed to thermal neutrons were performed at the TAPIRO fast reactor (ENEA, Italy). The proposed method, aimed at supporting the planning of neutron capture therapy, allows measurement of three-dimensional distributions of the therapy dose not only in tumors but also in normal tissue. This feature is very important, because

G. Gambarini; S. Agosteo; U. Danesi; F. Garbellini; B. Lietti; M. Mauri; G. Rosi

2001-01-01

91

Stellar neutron capture cross sections of the Ba isotopes.  

National Technical Information Service (NTIS)

The neutron capture cross sections of (sup 134)Ba, (sup 135)Ba, (sup 136)Ba, and (sup 137)Ba were measured in the energy range from 5 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the (sup 7)Li(p,n)(sup 7)Be rea...

F. Voss K. Wisshak K. Guber F. Kaeppeler G. Reffo

1994-01-01

92

Boron neutron capture therapy in Europe - status and perspective  

SciTech Connect

Since 1989, an international collaboration group, with support from the European Commission and from numerous national grant agencies, has been working to establish boron neutron capture therapy (BNCT) with epithermal neutrons as an alternative therapy for high-grade glioma. A total of 15 European countries are working toward this goal.

Moss, R.L. [Commission of the European Communities, Petten (Netherlands); Gabel, D. [Univ. of Bremen (Germany); Sauerwein, W. [Univ. of Essen (Germany)

1995-12-31

93

Neutron capture therapy beams at the MIT Research Reactor  

Microsoft Academic Search

Several neutron beams that could be used for neutron capture therapy at MITR-II are dosimetrically characterized and their suitability for the treatment of glioblastoma multiforme and other types of tumors are described. The types of neutron beams studied are: (1) those filtered by various thicknesses of cadmium, D2O, 6Li, and bismuth; and (2) epithermal beams achieved by filtration with aluminum,

J. R. Choi; S. D. Clement; O. K. Harling; R. G. Zamenhof

1990-01-01

94

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

95

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

NASA Astrophysics Data System (ADS)

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-? BaF2 scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

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

2009-03-01

96

Direct measurements of neutron capture on radioactive isotopes  

SciTech Connect

We simulated the response of a 4{pi} calorimetric {gamma}-detector array to decays of radioactive isotopes on the s-process path. The GEANT 3.21 simulation package was used. The main table contains estimates on the maximum sample size and required neutron flux based on the latest available neutron capture cross-section at 30 keV. The results are intended to be used to estimate the feasibility of neutron capture measurements with 4{pi} arrays using the time-of-flight technique.

Couture, A. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Reifarth, R. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)]. E-mail: reifarth@lanl.gov

2007-09-15

97

In Vivo Boron Uptake Determination for Boron Neutron Capture Synovectomy  

SciTech Connect

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

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

1999-06-06

98

Phantom models for neutron capture therapy.  

National Technical Information Service (NTIS)

The development of a two-dimensional phantom model using the neutron and photon transport code DOT-IV is detailed. The effects of varying basic parameters such as aperture width, neutron source energy and tissue composition have been studied. One importan...

G. J. Storr

1990-01-01

99

Measurement of Neutron Slowing Down Time in Light Water, Ice, Paraffin and Santowax  

Microsoft Academic Search

Measurements of the neutron slowing down times in light water, ice, paraffin and santowax have been made by pulsed neutron technique. Bursts of D-T neutrons of 0.1?see width were generated in moderator cubes of 40×40×40 cm. The slowing down neutrons were detected by bare as well as energy-selective filter-covered BF3 counters, and analyzed with a 256-channel time analyzer. Slowing down

Shigeyasu SAKAMOTO; Yoshihiko KANEKO; Fujiyoshi AKINO

1969-01-01

100

The Detector for Advanced Neutron Capture Experiments: A 4? BaF2 Detector for Neutron Capture Measurements at LANSCE  

NASA Astrophysics Data System (ADS)

The Detector for Advanced Neutron Capture Experiments (DANCE) is a 162-element 4? 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.; Agvaanluvsan, U.; Alpizar, A.; Bond, E. M.; Bredeweg, T. A.; Esch, E.-I.; Folden, C. M.; Greife, U.; Hatarik, R.; Haight, R. C.; Hoffman, D. C.; Hunt, L.; Kronenberg, A.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Schwantes, J. M.; Strottman, D. D.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.

2005-05-01

101

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

102

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

103

Proton linacs for boron neutron capture therapy  

SciTech Connect

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

Lennox, A.J. [Fermi National Accelerator Lab., Batavia, IL (United States)]|[Rush Univ., Chicago, IL (United States)

1993-08-01

104

Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture  

SciTech Connect

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

Scott Wilde, Raymond Keegan

2008-07-01

105

Thermal-neutron capture for A=26-35  

SciTech Connect

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

Chunmei, Z.; Firestone, R.B.

2001-06-01

106

Thermal-neutron capture for A=36-44  

SciTech Connect

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

Chunmei, Z.; Firestone, R.B.

2003-01-01

107

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

DOEpatents

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

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

1964-04-14

108

Non-Reactor Neutron Sources for BNCT (Boron Neutron Capture Therapy).  

National Technical Information Service (NTIS)

The focus of this study is the identification of key feasibility issues for the use of non-reactor neutron sources for Boron Neutron Capture Therapy (BNCT). Of the non-reactor neutron sources surveyed, the (7)Li(p,n) reaction appears to be the most favora...

D. M. Woodall E. E. Wills E. H. Ottewitte T. J. Dolan W. A. Neuman

1989-01-01

109

New opportunities in neutron capture research using advanced pulsed neutron sources  

SciTech Connect

The extraordinary neutron intensities available from the new spallation pulsed neutron sources open up exciting opportunities for basic and applied research in neutron nuclear physics. Prospective experiments are reviewed with particular attention to those with a strong connection to capture gamma-ray spectroscopy.

Bowman, C.D.

1987-08-01

110

Measurements of Neutron Capture Cross Section of Np for Fast Neutrons  

Microsoft Academic Search

The neutron capture cross section of Np has been measured for fast neutrons supplied at the center of the core in the Yayoi reactor. The activation method was used for the measurement, in which the amount of the product Np was determined by ?-ray spectroscopy using a Ge detector. The neutron flux at the center of the core calculated by

Hideo HARADA; Shoji NAKAMURA; Yuichi HATSUKAWA; Yosuke TOH; Atsushi KIMURA; Yuki ISHIWATARI; Atsushi YASUMI; Yukio MABUCHI; Tsutomu NAKAGAWA; Kazuo OKAMURA; Isao SAITOH; Yoshiaki OKA

2009-01-01

111

Evidence for Core-Excitation in Single Electron Capture by Slow Highly Charged Ions  

Microsoft Academic Search

The emission of characteristic M x-rays is observed in an experiment at KSU EBIS with slow highly charged Ta ions (5 keVq Ta^q+, q=39-48) capturing a well defined number of electrons in single collisions with rare gas atoms (He, Ar, Xe). A high characteristic M intensity is also measured for single electron capture and for charge states where initially the

Reinhold Schuch; Stojan Madzunkov; Eva Lindroth; Danny Fry

2000-01-01

112

Developments in Accelerator Based Boron Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

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

Green, S.

1998-06-01

113

Neutron-capture elements in extremely metal-poor stars  

NASA Astrophysics Data System (ADS)

Extremely metal-poor stars exhibit large scatter in the abundance ratios (e.g. [Sr/Fe] and [Ba/Fe], as well as [Sr/Ba]), and sometimes show very large enhancements of neutron-capture elements with respect to iron. However, recent abundance measurements for large samples of metal-poor stars suggest that neutron-capture elements are deficient in general in the lowest metallicity range and the scatter in their abundance ratios is rather small. The metallicity at which the abundance ratios show the largest scatter is dependent on elements: Ba shows largest scatter at [Fe/H] = -3, while Sr shows larger scatter at lower metallicity. Such trends suggest metallicity dependence of the contributions of nucleosynthesis processes that produce light and heavy neutron-capture elements. A clear cut-off is found in the Sr/Ba distribution at [Fe/H] = -3.5. This suggests a metallicity dependence of the process that provides light neutron-capture elements. Recent abundance studies for a large sample of very metal-poor stars found by the Sloan Digital Sky Survey (SDSS) discovered a carbon-enhanced metal-poor star that has [Fe/H] = -3.7 and a large excess of Sr with no detectable Ba. This is a similar feature to that found in the hyper metal-poor star HE 1327-2326 ([Fe/H] = -5.6) and indicates that the progenitors of such carbon-enhanced stars with no excess of heavy neutron-capture elements could be a source of light neutron-capture elements.

Aoki, Wako

2012-11-01

114

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

115

Theoretical and experimental physical methods of neutron-capture therapy  

NASA Astrophysics Data System (ADS)

This review is based to a substantial degree on our priority developments and research at the IR-8 reactor of the Russian Research Centre Kurchatov Institute. New theoretical and experimental methods of neutron-capture therapy are developed and applied in practice; these are: A general analytical and semi-empiric theory of neutron-capture therapy (NCT) based on classical neutron physics and its main sections (elementary theories of moderation, diffuse, reflection, and absorption of neutrons) rather than on methods of mathematical simulation. The theory is, first of all, intended for practical application by physicists, engineers, biologists, and physicians. This theory can be mastered by anyone with a higher education of almost any kind and minimal experience in operating a personal computer.

Borisov, G. I.

2011-09-01

116

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

117

Progress on the europium neutron capture study using DANCE  

NASA Astrophysics Data System (ADS)

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 151,153Eu targets were measured recently using a 4? ?-ray calorimeter array DANCE located at the Los Alamos Neutron Science Center for En = 0.1 100 keV. The progress on the data analysis efforts is given in the present paper. The ?-ray multiplicity distributions for the Eu targets and Be backing are significantly different. The ?-ray multiplicity distribution is found to be the same for different neutron energies for both 151Eu and 153Eu. The statistical simulation to model the ?-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.; Be?vá?, F.; Krti?ka, M.

2007-08-01

118

Contribution of Massive Stars to the Production of Neutron Capture Elements  

NASA Astrophysics Data System (ADS)

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

Federman, Steven

2009-07-01

119

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

PubMed

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

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

1990-01-01

120

Boronated carbohydrate derivatives as potential boron neutron capture therapy reagents.  

PubMed

The treatment of cancer remains one of the most challenging problems for humanity. Boron neutron capture therapy is a binary approach for cancer treatment that is particularly attractive in treating high-grade gliomas and metastatic brain tumors. Among the types of boron-containing molecules used as boron neutron capture therapy agents, boronated carbohydrate derivatives have received significant attention because of their preferential uptake by growing tumor cells. This review provides a summary of the recent developments in the chemistry of carborane-containing carbohydrates. PMID:23617431

Marepally, Srinivasa R; Yao, Min-Liang; Kabalka, George W

2013-04-01

121

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

122

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

123

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

124

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

NASA Astrophysics Data System (ADS)

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 241Am for neutron energies between thermal and 320 keV. Preliminary results were also obtained for 243Am for neutron energies between 10 eV and 250 keV. The results on concurrent neutron-induced fission and neutron-capture measurements on 242mAm 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,?) events from (n,f) events. The first direct observation of neutron capture on 242mAm in the resonance region in between 2 and 9 eV of the neutron energy was obtained.

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

2009-01-01

125

Neutron capture therapy beams at the MIT Research Reactor.  

PubMed

Several neutron beams that could be used for neutron capture therapy at MITR-II are dosimetrically characterized and their suitability for the treatment of glioblastoma multiforme and other types of tumors are described. The types of neutron beams studied are: 1) those filtered by various thicknesses of cadmium, D2O, 6Li, and bismuth; and 2) epithermal beams achieved by filtration with aluminum, sulfur, cadmium, 6Li, and bismuth. Measured dose vs. depth data are presented in polyethylene phantom with references to what can be expected in brain. The results indicate that both types of neutron beams are useful for neutron capture therapy. The first type of neutron beams have good therapeutic advantage depths (approximately 5 cm) and excellent in-phantom ratios of therapeutic dose to background dose. Such beams would be useful for treating tumors located at relatively shallow depths in the brain. On the other hand, the second type of neutron beams have superior therapeutic advantage depths (greater than 6 cm) and good in-phantom therapeutic advantage ratios. Such beams, when used along with bilateral irradiation schemes, would be able to treat tumors at any depth in the brain. Numerical examples of what could be achieved with these beams, using RBEs, fractionated-dose delivery, unilateral, and bilateral irradiation are presented in the paper. Finally, additional plans for further neutron beam development at MITR-II are discussed. PMID:2176454

Choi, J R; Clement, S D; Harling, O K; Zamenhof, R G

1990-01-01

126

Neutron capture therapy beams at the MIT Research Reactor  

SciTech Connect

Several neutron beams that could be used for neutron capture therapy at MITR-II are dosimetrically characterized and their suitability for the treatment of glioblastoma multiforme and other types of tumors are described. The types of neutron beams studied are: (1) those filtered by various thicknesses of cadmium, D2O, 6Li, and bismuth; and (2) epithermal beams achieved by filtration with aluminum, sulfur, cadmium, 6Li, and bismuth. Measured dose vs. depth data are presented in polyethylene phantom with references to what can be expected in brain. The results indicate that both types of neutron beams are useful for neutron capture therapy. The first type of neutron beams have good therapeutic advantage depths (approximately 5 cm) and excellent in-phantom ratios of therapeutic dose to background dose. Such beams would be useful for treating tumors located at relatively shallow depths in the brain. On the other hand, the second type of neutron beams have superior therapeutic advantage depths (greater than 6 cm) and good in-phantom therapeutic advantage ratios. Such beams, when used along with bilateral irradiation schemes, would be able to treat tumors at any depth in the brain. Numerical examples of what could be achieved with these beams, using RBEs, fractionated-dose delivery, unilateral, and bilateral irradiation are presented in the paper. Finally, additional plans for further neutron beam development at MITR-II are discussed.

Choi, J.R.; Clement, S.D.; Harling, O.K.; Zamenhof, R.G. (Massachusetts Institute of Technology, Cambridge (USA))

1990-01-01

127

Measuring parity violation using the neutron capture reaction  

SciTech Connect

Measuring parity violation using the total capture reaction has certain advantages over neutron transmission experiments. Very much less material is required for targets, a necessity when dealing with separated isotopes. The capture reaction is also quite sensitive to very weak resonances. These advantages indicated the need to construct a near 4[pi] gamma ray detector for use at LANSCE. A design for such a detector has been completed. Issues influencing the design and the final design parameters will be discussed in detail.

Frankle, C.M.; Bowman, J.D.; Seestrom, S.J. (Los Alamos National Lab., NM (United States)); Roberson, N.R. (Duke Univ., Durham, NC (United States) Triangle Universities Nuclear Lab., Durham, NC (United States)); Sharapov, E.I. (Joint Inst. for Nuclear Research, Dubna (Russian Federation))

1993-01-01

128

Dose imaging and profiling for boron neutron capture therapy planning  

Microsoft Academic Search

Imaging and profiling of the absorbed dose in tissue-equivalent gel-phantoms exposed to thermal neutrons were performed at the TAPIRO fast reactor (ENEA, Italy). The proposed method, aimed at supporting the planning of Neutron Capture Therapy (NCT), allows to measure 3D distributions of the therapy dose not only in tumors, but also in the healthy tissue. This feature is very important,

G. Gambarini; S. Agosteo; U. Danesi; F. Garbellini; B. Lietti; M. Mauri; E. Nava; G. Rosi; R. Tinti

2000-01-01

129

A Critical Assessment of Boron Neutron Capture Therapy: An Overview  

Microsoft Academic Search

Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10 is irradiated with neutrons of the appropriate energy to produce high-energy alpha particles and recoiling lithium-7 nuclei. BNCT has been used clinically to treat patients with high-grade gliomas, and a much smaller number with primary and metastatic melanoma. The purpose of this special issue of

Rolf F. Barth

2003-01-01

130

A critical assessment of boron neutron capture therapy: an overview  

Microsoft Academic Search

Summary  Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron-10 is irradiated with neutrons\\u000a of the appropriate energy to produce high-energy alpha particles and recoiling lithium-7 nuclei. BNCT has been used clinically\\u000a to treat patients with high-grade gliomas, and a much smaller number with primary and metastatic melanoma. The purpose of\\u000a this special issue of

Rolf F. Barth

2003-01-01

131

New measurement of neutron capture resonances in Bi209  

Microsoft Academic Search

The neutron capture cross section of Bi209 has been measured at the CERN n_TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which led to a practically negligible neutron sensitivity. Additional experimental sources of systematic error, such as the electronic threshold in the detectors, summing of gamma-rays, internal electron conversion,

C. Domingo-Pardo; U. Abbondanno; G. Aerts; H. Álvarez-Pol; F. Alvarez-Velarde; S. Andriamonje; J. Andrzejewski; P. Assimakopoulos; L. Audouin; G. Badurek; P. Baumann; F. Becvár; E. Berthoumieux; F. Calviño; D. Cano-Ott; R. Capote; A. Carrillo De Albornoz; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; A. Couture; J. Cox; M. Dahlfors; S. David; I. Dillman; R. Dolfini; W. Dridi; I. Duran; C. Eleftheriadis; M. Embid-Segura; L. Ferrant; A. Ferrari; R. Ferreira-Marques; L. Fitzpatrick; H. Frais-Koelbl; K. Fujii; W. Furman; R. Gallino; I. Goncalves; E. Gonzalez-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; C. Guerrero; F. Gunsing; B. Haas; R. Haight; M. Heil; A. Herrera-Martinez; M. Igashira; S. Isaev; E. Jericha; Y. Kadi; F. Käppeler; D. Karamanis; D. Karadimos; M. Kerveno; V. Ketlerov; P. Koehler; V. Konovalov; E. Kossionides; M. Krticka; C. Lamboudis; H. Leeb; A. Lindote; I. Lopes; M. Lozano; S. Lukic; J. Marganiec; L. Marques; S. Marrone; P. Mastinu; A. Mengoni; P. M. Milazzo; C. Moreau; M. Mosconi; F. Neves; H. Oberhummer; M. Oshima; S. O'Brien; J. Pancin; C. Papachristodoulou; C Papadopoulos; N. Patronis; A. Pavlik; P. Pavlopoulos; L. Perrot; R. Plag; A. Plompen; A Plukis; C. Pretel; J. Quesada; T. Rauscher; R. Reifarth; M. Rosetti; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; L. Sarchiapone; I. Savvidis; C. Stephan; G. Tagliente; J. L. Tain; L. Tassan-Got; R. Terlizzi; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M. C. Vincente; V. Vlachoudis; R. Vlastou; F. Voss; S. Walter; H. Wendler; M. Wiescher; K. Wisshak

2006-01-01

132

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

133

Direct effect in DNA radiolysis. Boron neutron capture enhancement of radiolysis in a medical fast-neutron beam.  

PubMed

SècheThis paper is devoted to the study of the molecular basis of the boron neutron capture enhancement of fast-neutron radiotherapy. Plasmid DNA was irradiated with a medical fast-neutron beam in the presence of either (10)B or (11)B. The number of induced SSBs and DSBs was much higher in samples containing (10)B compared to (11)B. The additional breaks are attributed to the nuclear reaction (10)B(n, alpha)(7)Li induced by the capture by (10)B of thermal neutrons produced in the medium by scattering and slowing down of neutrons. Irradiation in the presence of DMSO (OH radical scavenger) allows the number of nonscavengeable breaks to be determined. The ratio DSB/SSB is within the range of those observed with heavy ions, in good agreement with the hypothesis that the additional breaks are due to alpha particles and recoil lithium nuclei. The simulation of the energy deposition along the paths of the alpha and (7)Li particles allows the calculation of core and penumbra track volumes. Further, the number of plasmids encountered by the core and the penumbra was evaluated. Their number was compared to the nonscavengeable additional breaks. Since the two sets of values are of the same order of magnitude, we conclude that the nonscavengeable additional SSBs and DSBs could be due to direct effects. PMID:12175306

Sèche, Edouard; Sabattier, Roland; Bajard, Jean-Claude; Blondiaux, Gilbert; Breteau, Noël; Spotheim-Maurizot, Mélanie; Charlier, Michel

2002-09-01

134

Neutron sources for a neutron capture therapy facility  

SciTech Connect

Recent advances in the development of boron pharmaceuticals have reopened the possibility of using epithermal neutrons to treat brain tumors containing boron-10. This paper summarizes the approaches being used to generate the neutron sources and identifies specific areas where more research and development are needed.

Lennox, A.J.

1993-04-01

135

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

136

Fast neutron capture with a white neutron source  

NASA Astrophysics Data System (ADS)

A system to measure gamma rays following fast neutron reactions was developed. The neutron beam is produced by bombarding a thick tantalum target with the 800 MeV proton beam from the LAMPF accelerator. Incident neutron energies, from 1 to over 200 MeV, are determined by their times of flight over a 7.6-m flight path. The gamma rays are detected in five 7.6 x 7.6 cm cylindrical bismuth germanate (BGO) detectors which span an angular range from 45(0) to 145(0) in the reaction plane. The system measures simultaneously the cross section and angular distribution of gamma rays as a function of neutron energy. The data for the (40)Ca(n,(GAMMA)0) reaction in the region of the giant dipole resonance demonstrate the unique capabilities of this system. Future developments to the neutron source which will enhance the capabilities of the system are presented.

Wender, S. A.; Auchampaugh, G. F.

137

A New Neutron-Capture Detector for Coincidence Counting  

NASA Astrophysics Data System (ADS)

Quantities of special nuclear material (SNM) are measured by counting coincident neutrons. This technique relies on spontaneous fission, in which more than one neutron is released for most events. Neutron coincidence counting (NCC) uses thermal neutron detectors. A problem with measurements of impure materials is that the neutron count rate, which determines the accidental coincidence rate, can be dominated by uncorrelated neutrons. An elevated rate of accidental coincidences can destroy the detection sensitivity. By reducing the detector’s die-away time (t, the time it takes to detect a neutron), true coincidence events are registered more promptly and the accidental rate reduced proportionally. The t of current counters based on 3He proportional detectors is 50 ms. A new detector is being developed with a shorter t of 5 ms for NCC of impure SNM. It uses alternating layers of a scintillator/6Li powder mixture and ribbons of optical fiber for light transport. Neutrons are thermalized and then detected by capture on 6Li. The reaction products deposit energy in the scintillator. The light is transported by the fibers to photomultiplier tubes. However, the detector is sensitive to both gamma rays and neutrons. Separating the two is essential for successful operation. This paper presents a description and evaluation of the new detector. Pulse shape analysis is discussed for discrimination between gamma rays and neutrons.

Browne, Michael C.; Ensslin, Norbert; Geist, William H.; Ianakiev, Kiril; Mayo, Douglas; Russo, Phyllis A.; Sweet, Martin R.

2000-04-01

138

Absolute cross sections for charge capture from Rydberg targets by slow highly charged ions  

Microsoft Academic Search

A crossed beam experiment has been used to measure absolute charge capture cross sections in collisions of slow highly charged xenon ions with laser excited Rydberg atoms. The cross sections were measured for scaled projectile velocities nvp from 1.0 to 6.0, for projectile charges of 8, 16, 32, and 40, where n is the principal quantum number of the target

B. D. Depaola; M.-T. Huang; S. Winecki; M. P. Stöckli; Y. Kanai; S. R. Lundeen; C. W. Fehrenbach; S. A. Arko

1995-01-01

139

Magnetic substates populated by double electron capture in slow ion atom collisions  

SciTech Connect

The work presented here is the first measurement of the angular distribution of Auger electrons following double electron capture by a beam of slow highly charged ions. From this, relative cross sections for the population of individual M{sub L} substates were determined.

Randall, K.L.

1990-12-13

140

Neutron capture by light nuclei at astrophysical energies  

NASA Astrophysics Data System (ADS)

Results obtained in the studies of radiative neutron capture on light nuclei at thermal and astrophysical energies are reviewed. The capture reactions in question are part of the primordial nucleosynthesis reaction chain underlying formation and development of the Universe. The reactions are treated within the potential cluster model with orbital states of clusters classified by Young diagrams. It is demonstrated that the intercluster potentials obtained from the phase shift analysis and description of the main characteristics of bound nuclear states in cluster channels can be used for the analysis of radiative capture characteristics.

Dubovichenko, S. B.

2013-09-01

141

Thermal neutron capture cross section in deuterium  

SciTech Connect

The radiative thermal nD capture cross section sigma/sub D/ was measured by the time-of-flight method at the IBR-30 pulsed reactor using Ge(Li) detector, D/sub 2/O water sample and the sigma/sub Cl/ thermal cross section as the standard. The result 487(24) ..mu..b is in favor of the theoretical value found in the frame of the three body problem.

Alfimenkov, V.P.; Borzakov, S.B.; Wierzbicki, J.; Osipenko, B.P.; Pikelner, L.B.; Tishin, V.G.; Sharapov, E.I.

1980-09-01

142

Thermal Neutron Capture Cross Section in Deuterium  

Microsoft Academic Search

The radiative thermal nD capture cross section sigma\\/sub D\\/ was measured by the time-of-flight method at the IBR-30 pulsed reactor using Ge(Li) detector, DâO water sample and the sigma\\/sub Cl\\/ thermal cross section as the standard. The result 487(24) ..mu..b is in favor of the theoretical value found in the frame of the three body problem.

V. P. Alfimenkov; S. B. Borzakov; J. Wierzbicki; B. P. Osipenko; L. B. Pikelner; V. G. Tishin; E. I. Sharapov

1980-01-01

143

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

144

Updates for Gadolinium neutron capture measurements at DANCE  

NASA Astrophysics Data System (ADS)

Neutron capture reactions for several isotopes of Gadolinium have been measured at DANCE array in Los Alamos Neutron Science Center. Progress on the analysis is discussed. The detector response function of DANCE array is presented in connection with the statistical gamma-ray decay cascade simulation. In the region of separated neutron resonances, the statistical gamma-ray decay cascade is simulated using the DICEBOX code. Various models for the photon strength function and level density are used as input. The output of simulations is compared with DANCE data.

Dashdorj, Dugersuren; Mitchell, G. E.; Baramsai, B.; Chankova, R.; Chyzh, A.; Walker, C.; Agvaanluvsan, U.; Becker, J. A.; Parker, W.; Wu, C. Y.; Bredeweg, T.; Couture, A.; Haight, R.; Jandel, M.; O'Donnell, J.; Rundberg, R.; Wouters, J.; Ullmann, J.; Vieira, D.; Becvar, F.; Krticka, M.

2007-10-01

145

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

2012-05-01

146

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

147

Boron neutron capture therapy: Brain Tumor Treatment Evaluation Program  

Microsoft Academic Search

The United States (US) Department of Energy (DOE) recently initiated a focused, multidisciplined program to evaluate Boron Neutron Capture Therapy (BNCT) for the treatment of brain tumors. The program, centered at the DOE\\/endash\\/Idaho National Engineering Laboratory (INEL), will develop the analytical, diagnostic and treatment tools, and the database required for BNCT technical assessment. The integrated technology will be evaluated in

M. L. Griebenow; R. V. Dorn; P. R. Gavin; J. H. Spickard

1988-01-01

148

Fast Neutron Capture and the Microscopic Isovector Optical Potential.  

National Technical Information Service (NTIS)

Neutron capture cross-sections are calculated with the direct-semidirect model employing the complex microscopic optical potential recently calculated by Jeukenne, Lejoune and Mahaux. The data for exp 89 Y, Ce and exp 208 Pb for E/sub n/=6-16 MeV agree we...

D. R. Chakrabarty S. K. Gupta

1980-01-01

149

Boron Hydride Derivatives for Neutron Capture Therapy. Antibody Approach.  

National Technical Information Service (NTIS)

A number of borane derivatives which have potential use in binding to proteins for neutron capture therapy have been synthesized from orthocarborane (C2B10H12) and from decahydrodecaborate(2-). These modifying reagents contain either amine, imido ester, o...

H. S. Wong E. I. Tolpin W. N. Lipscomb

1973-01-01

150

Radiobiology of boron neutron capture therapy: Studies using small animals.  

National Technical Information Service (NTIS)

The boron-10 nucleus captures thermal neutrons efficiently and immediately disintegrates to release high linear-energy-transfer (LET) charged (alpha) and (sup 7)Li particles that travel less than 10 (mu)m (1 cell diameter) in tissue. Given sufficient sele...

J. A. Coderre G. M. Morris J. A. Hopewell

1994-01-01

151

Thermal Neutron Capture onto the Stable Tungsten Isotopes  

NASA Astrophysics Data System (ADS)

Thermal neutron-capture measurements of the stable tungsten isotopes have been carried out using the guided thermal-neutron beam at the Budapest Reactor. Prompt singles spectra were collected and analyzed using the HYPERMET ?-ray analysis software package for the compound tungsten systems 183W, 184W, and 187W, prepared from isotopically-enriched samples of 182W, 183W, and 186W, respectively. These new data provide both confirmation and new insights into the decay schemes and structure of the tungsten isotopes reported in the Evaluated Gamma-ray Activation File based upon previous elemental analysis. The experimental data have also been compared to Monte Carlo simulations of ?-ray emission following the thermal neutron-capture process using the statistical-decay code DICEBOX. Together, the experimental cross sections and modeledfeeding contribution from the quasi continuum, have been used to determine the total radiative thermal neutron-capture cross sections for the tungsten isotopes and provide improved decay-scheme information for the structural- and neutron-data libraries.

Hurst, A. M.; Firestone, R. B.; Sleaford, B. W.; Summers, N. C.; Revay, Zs.; Szentmiklósi, L.; Belgya, T.; Basunia, M. S.; Capote, R.; Choi, H.; Dashdorj, D.; Escher, J.; Krticka, M.; Nichols, A.

2012-02-01

152

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

153

Neutron capture by fissile and fertile actinide targets  

SciTech Connect

For fissile actinide targets {sup 233}U, {sup 235}U and {sup 239}Pu the capture cross sections are strongly influenced by the target spin, fission transition states spectroscopy and fission/{gamma}-emission competition of the compound nuclides. The capture cross sections were obtained via a consistent description of fission and elastic/inelastic scattering, (n,{gamma}f) reaction being included.For neutron capture reactions on even-even U, Pu and Cm nuclei the methods, proven in case of {sup 232}Th(n,{gamma}) and {sup 238}U(n,{gamma}) data analysis are used. Calculated {sup 240}Pu(n,{gamma}) and {sup 244}Cm(n,{gamma}) reaction cross sections shapes are much similar to that, observed for the {sup 238}U(n,{gamma}) and {sup 232}Th(n,{gamma}) reactions. Differences are due to fission and neutron emission competition, which depends on the (Z,N)-composition of the compound nucleus.

Maslov, Vladimir M. [Joint Institute of Nuclear and Energy Research, 220109, Minsk (Belarus)

2009-01-28

154

Current status of fast-neutron-capture calculations  

NASA Astrophysics Data System (ADS)

Neutron capture cross sections and capture gamma ray spectra, in the framework of the Hauser-Feshbach statistical model and neutrons from the resonance region up to several MeV are studied. 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 Y-89 + 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.

1982-04-01

155

Gamma Spectrum from Neutron Capture on Tungsten Isotopes  

SciTech Connect

An evaluation of thermal neutron capture on the stable tungsten isotopes is presented, with preliminary results for the compound systems 183;184;185;187W. The evaluation procedure compares the g-ray cross-section data collected at the Budapest reactor, with Monte Carlo simulations of g-ray emission following the thermal neutron-capture process. The statistical-decay code DICEBOX was used for the Monte Carlo simulations. The evaluation yields new gamma rays in 185W and the confirmation of spins in 187W, raising the number of levels below which the level schemes are considered complete, thus increasing the number of levels that can be used in neutron data libraries.

Hurst, Aaron; Summers, Neil; Sleaford, Brad; Firestone, Richard B; Belgya, T.; Revay, Z.S.

2010-04-29

156

[Liposomal boron delivery system for neutron capture therapy].  

PubMed

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

Nakamura, Hiroyuki

2008-02-01

157

Neutronic design of a fission converter-based epithermal neutron beam for neutron capture therapy  

SciTech Connect

To meet the needs for neutron capture theory (NCT) irradiations, a high-intensity, high-quality fusion converter-based epithermal neutron beam has been designed for the MITR-II research reactor. This epithermal neutron beam, capable of delivering treatments in a few minutes with negligible background contamination from fast neutrons and photons, will be installed in the present thermal column and hohlraum of the 5-MW MITR-II research reactor. Spent or fresh MITR-II fuel elements will be used to fuel the converter. With a fission converter power of {approximately}80 kW using spent fuel, epithermal fluxes (1 eV < E < 10 keV) in excess of 10{sup 10} n/cm{sup 2} {center_dot} s are achievable at the target position with negligible photon and fast neutron contamination, i.e., <2 {times} 10{sup {minus}11}cGy-cm{sup 2}/n. With the currently available {sup 10}B delivery compound boronophenylalanine-fructose, average therapeutic ratios of {approximately}5 can be achieved using this beam for brain irradiations with deep effective penetration ({approximately}9.5 cm) and high dose rates of up to 400 to 600 RBE cGy/min. If NCT becomes an accepted therapy, fission converter-based beams constructed at existing reactors could meet a large fraction of the projected requirements for intense, low-background epithermal neutron beams at a relatively low cost. The results of an extensive set of neutronic design studies investigating all components of the beam are presented. These detailed studies can be useful as guidance for others who may wish to use the fission converter approach to develop epithermal beams for NCT.

Kiger, W.S. III; Sakamoto, S.; Harling, O.K. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1999-01-01

158

``Fast neutron capture with a white neutron source''  

NASA Astrophysics Data System (ADS)

A system has been developed at the Los Alamos National Laboratory to measure gamma-rays following fast neutron reactions. The neutron beam is produced by bombarding a thick tantalum target with the 800 MeV proton beam from the LAMPF accelerator. Incident neutron energies, from 1 to over 200 MeV, are determined by their times of flight over a 7.6-m flight path. The gamma-rays are detected in five 7.6×7.6-cm cylindrical bismuth germanate (BGO) detectors which span an angular range from 45° to 145° in the reaction plane. With this system it is possible to simultaneously measure the cross section and angular distribution of gamma-rays as a function of neutron energy. The results for the cross section of the 12C(n,n'?=4.44 MeV) reaction at 90° and 125° show good agreement with previous measurements, while the complete angular distributions show the need for a large a4 coefficient which was not previously observed. Preliminary results for the 12C(n,n'?=15.1 MeV) reaction have also been obtained. The data obtained for the 40Ca(n,?0) reaction in the region of the giant dipole resonance demonstrate the unique capabilities of this system. Future developments to the neutron source which will enhance the capabilities of the system will be presented.

Wender, S. A.; Auchampaugh, G. F.

1985-01-01

159

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

National Technical Information Service (NTIS)

A program is under development at the Idaho National Engineering Laboratory (INEL) that involves using the Power Burst Facility (PBF) for research into Boron Neutron Capture Therapy (BNCT). BNCT utilizes the ionizing energy from boron-neutron capture to s...

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

1989-01-01

160

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

161

An improved neutron collimator for brain tumor irradiations in clinical boron neutron capture therapy  

Microsoft Academic Search

To improve beam penetration into a head allowing the treatment of deeper seated tumors, two neutron collimators were built sequentially and tested for use in the clinical boron neutron capture therapy (BNCT) program at the epithermal neutron irradiation facility of the Brookhaven Medical Research Reactor. The collimators were constructed from lithium-impregnated polyethylene, which comprises LiâCOâ powder (â93% enriched isotopic ⁶Li)

Hungyuan B. Liu; D. D. Greenberg; J. Capala; F. J. Wheeler

1996-01-01

162

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

163

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

Microsoft Academic Search

Summary  This paper reviews the development of low-energy light ion accelerator-based neutron sources (ABNSs) for the treatment of\\u000a brain tumors through an intact scalp and skull using boron neutron capture therapy (BNCT). A major advantage of an ABNS for\\u000a BNCT over reactor-based neutron sources is the potential for siting within a hospital. Consequently, light-ion accelerators\\u000a that are injectors to larger machines

Thomas E. Blue; Jacquelyn C. Yanch

2003-01-01

164

Accelerator-based Epithermal Neutron Sources for Boron Neutron Capture Therapy of Brain Tumors  

Microsoft Academic Search

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

Thomas E. Blue; Jacquelyn C. Yanch

2003-01-01

165

Neutron Transfer Reactions: Surrogates for Neutron Capture for Basic and Applied Nuclear Science  

NASA Astrophysics Data System (ADS)

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 130,132Sn, 134Te and 75As are discussed.

Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, S. D.; Peters, W. A.; Adekola, A.; Allen, J.; Bardayan, D. W.; Becker, J. A.; Blackmon, J. C.; Chae, K. Y.; Chipps, K. A.; Erikson, L.; Gaddis, A.; Harlin, C.; Hatarik, R.; Howard, J.; Jandel, M.; Johnson, M. S.; Kapler, R.; Krolas, W.; Liang, F.; Livesay, R. J.; Ma, Z.; Matei, C.; Matthews, C.; Moazen, B.; Nesaraja, C. D.; O'Malley, P.; Patterson, N.; Paulauskas, S. V.; Pelham, T.; Pittman, S. T.; Radford, D.; Rogers, J.; Schmitt, K.; Shapira, D.; Shriner, J. F.; Sissom, D. J.; Smith, M. S.; Swan, T.; Thomas, J. S.; Vieira, D. J.; Wilhelmy, J. B.; Wilson, G. L.

2009-03-01

166

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.; Peters, W. A.; Allen, J.; Hatarik, R.; Matthews, C.; O'Malley, P. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Jones, K. L. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 (United States); Kozub, R. L.; Howard, J.; Patterson, N.; Paulauskas, S. V.; Rogers, J.; Sissom, D. J. [Department of Physics, Tennessee Technological University, Cookeville, TN 38505 (United States); Pain, S. D. [Department of Physics and Astronomy, Rutgers University, New Brunswick, NJ 08903 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Adekola, A. [Department of Physics and Astronomy, Ohio University, Athens, OH 45703 (United States); Bardayan, D. W.; Blackmon, J. C.; Liang, F.; Nesaraja, C. D.; Pittman, S. T. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)] (and others)

2009-03-10

167

Measurement of Neutron Capture Cross Sections of Selenium Isotopes  

NASA Astrophysics Data System (ADS)

There have been numerous measurements of the neutron capture cross sections of the stable Se isotopes, most dating from at least 40 years ago. The various results for individual isotopes are often in poor agreement with one another, but as yet there has been no attempt at a systematic measurement of the capture cross sections leading to all seven radioisotopes formed from capture by natural Se, which range in halflife from 17 s to 120 d. Using cadmium-shielded and unshielded irradiations of natural Se in various irradiation sites in OSU's TRIGA reactor, we have determined the thermal cross sections and resonance integrals for captures leading to ^75,77m,79m,81g,81m,83g,83mSe.

Dearmon, Howard D.; Krane, Kenneth S.

2011-10-01

168

Fricke gel dosimetry in boron neutron capture therapy.  

PubMed

Gel dosimetry allows three-dimensional (3D) measurement of absorbed dose in tissue-equivalent dosemeter phantoms. Gel phantoms are imaged using optical techniques. In neutron capture therapy (NCT), properly designed gel dosemeters can give 3D dose distributions, due to the various components of the secondary radiation, in phantoms exposed in the thermal or epithermal column of a nuclear reactor. In addition to the therapeutic dose arising from the reaction 10B(n,alpha)7Li, the other dose components are also obtainable, i.e. the gamma dose (due to reactor background and to the reaction 1H(n,gamma)2H of thermal neutrons with hydrogen, the dose due to protons emitted in the reaction 14N(n,p)14C of thermal neutrons with nitrogen and the dose due to recoil protons resulting from elastic scattering of epithermal neutrons. PMID:12382781

Gambarini, G; Birattari, C; Colombi, C; Pirola, L; Rosi, G

2002-01-01

169

Stellar neutron capture cross sections of the tin isotopes.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 114Sn, 115Sn, 116Sn, 117Sn, 118Sn, and 120Sn were measured in the enrgy 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. This allowed to lower the threshold in sum energy and resulted in a significantly increased efficiency for capture events. The experiment was difficult due to the small (n, ?) cross sections of the proton magic tin isotopes, and due to the comparably low enrichment of the rare isotopes 114Sn and 115Sn. This caused significant corrections for capture of scattered neutrons and for isotopic impurities, but the high efficiency and the spectroscopic quality of the BaF2 detector allowed to determine these corrections reliably. Typical overall uncertainties of 1 - 2% could be achieved for the cross section ratios, five times smaller compared to existing data. Based on these results, Maxwellian averaged (n, ?) cross sections were calculated for thermal energies between kT = 10 keV and 100 keV.

Wisshak, K.; Voss, F.; Theis, C.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Reffo, G.

1995-08-01

170

Neutron capture cross sections of even-mass tellurium isotopes  

SciTech Connect

Neutron capture by the stable even-mass Te isotopes (A=120 to 130) produces in the neighboring odd-neutron isotopes a low-spin ground state (1/2{sup +} or 3/2{sup +}) and a high-spin (11/2{sup -}) isomeric state. Following neutron irradiation of samples of Te of natural isotopic abundance, thermal cross sections and resonance integrals have been determined for all of the odd-mass radioactive ground states and isomers produced in the capture process. By comparing Cd-shielded and unshielded irradiations, it was possible to correct for the effect of capture by epithermal neutrons and so obtain consistent values for the thermal cross sections. Half-lives have been remeasured for {sup 121g,m}Te, {sup 127m}Te, and {sup 131m}Te. The previously observed systematic behavior of the thermal cross sections leading to the low-spin and high-spin states in Sn does not appear for the similar states in the Te isotopes.

Eastman, M. C.; Krane, K. S. [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States)

2008-02-15

171

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

172

Neutron capture of 46Ca at thermonuclear energies  

NASA Astrophysics Data System (ADS)

The measurement of the neutron capture reaction 46Ca(n,?)47Ca is of astrophysical interest, because 46Ca is bypassed by charged-particle reactions. The nucleus 46Ca is produced and destroyed by neutron-induced nucleosynthesis in hydrostatic helium, carbon, and neon burning through the reaction chain 45Ca(n,?)46Ca(n,?)47Ca. At the Karlsruhe and Tübingen 3.75 MV Van de Graaff accelerators the thermonuclear 46Ca(n,?)47Ca(4.54 d) cross section was measured by the activation technique via the 1297.09 keV ?-ray line of the 47Ca decay. Samples of CaCO3 enriched in 46Ca by 5% were irradiated between two gold foils which served as capture standards using the 7Li(p,n) and T(p,n) reactions. The capture cross section was measured at the mean neutron energies 30, 104, 149, 180, and 215 keV, respectively. Maxwellian averaged capture cross sections were measured at the quasithermal neutron energies kT=25 and 52 keV, respectively. It was found that the 46Ca(n,?)47Ca cross section in the thermonuclear energy region and at thermal energy is dominated by an s-wave resonance at 28.4 keV with a neutron width ?n=(17.4+3.6-2.8) keV and a radiation width ??=(2.4+/-0.3) eV. The stellar reaction rate is determined in the temperature range from kT=1 to 250 keV and is compared with previous investigations using Hauser-Feshbach calculations or experimental cross section data. The astrophysical consequences of the new stellar reaction rate with respect to the nucleosynthetic abundance of 46Ca are discussed.

Mohr, P.; Sedyshev, P. V.; Beer, H.; Stadler, W.; Oberhummer, H.; Popov, Yu. P.; Rochow, W.

1999-06-01

173

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

174

Research in Boron Neutron Capture Therapy at MIT LABA  

SciTech Connect

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

Yanch, J.C. [Department of Nuclear Engineering, Cambridge, Massachusetts 02139 (United States); Shefer, R.E.; Klinkowstein, R.E. [Newton Scientific Incorporated, Cambridge, Massachusetts 02141 (United States); Howard, W.B.; Song, H. [Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Blackburn, B.; Binello, E. [Department of Nuclear Engineering, Cambridge, Massachusetts 02139 (United States)

1997-02-01

175

Absolute cross sections for charge capture from Rydberg targets by slow highly charged ions  

Microsoft Academic Search

A crossed beam experiment has been used to measure absolute charge capture cross sections in collisions of slow highly charged xenon ions with laser excited Rydberg atoms. The cross sections were measured for scaled projectile velocities {ital nv}{sub {ital p}} from 1.0 to 6.0, for projectile charges of 8, 16, 32, and 40, where {ital n} is the principal quantum

B. D. DePaola; M.-T. Huang; S. Winecki; M. P. Stoeckli; Y. Kanai; S. R. Lundeen; C. W. Fehrenbach; S. A. Arko

1995-01-01

176

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

Microsoft Academic Search

Recent measurements of autoionization electrons produced in slow, highly charged ion-atom collisions are reviewed. Mechanisms for double electron capture into equivalent and nonequivalent configurations are analyzed by comparing the probabilities for the creation of LâLââX Coster Kronig electrons and L-Auger electrons. It is shown that the production of the Coster-Kronig electrons is due to electron correlation effects whose analysis leads

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

1986-01-01

177

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

Microsoft Academic Search

Recent measurements [1,2] of autoionization electrons produced in slow, highly charged ion-atom collisions are reviewed. Mechanisms for double electron capture into equivalent and nonequivalent configurations are analyzed by comparing the probabilities for the creation of L-Auger electrons and L1L23X Coster-Kronig electrons. It is shown that the production of the Coster-Kronig electrons is due to electron correlation effects whose analysis leads

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

1987-01-01

178

Electron Capture by Slow Highly-Charged Neon and Argon Ions from Molecular and Atomic Hydrogen  

Microsoft Academic Search

Electron capture cross sections for low velocity (10('6)-10('7) cm\\/s) highly charged Ne('q+) (2 (LESSTHEQ) q (LESSTHEQ) 7) and Ar('q+) (2 (LESSTHEQ) q (LESSTHEQ) 10) projectiles incident on molecular and atomic hydrogen targets have been measured. A recoil ion source that uses the collisions of fast heavy (1 MeV\\/amu) ions with target gas atoms was utilized to produce slow highly charged

Cuneyt Can

1983-01-01

179

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

180

Abundance Patterns of Neutron-Capture Elements in the Interstellar Medium  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

182

Impact of the phonon coupling on the radiative neutron capture  

SciTech Connect

Inclusion of the coupling of quasiparticle degrees of freedom with phonon degrees is a natural extention of the standard QRPA approach. The paper presents the quantitative impact of this phonon coupling on the dipole strength and radiative neutron capture for the stable {sup 124}Sn and very exotic {sup 150}Sn isotopes, as an illustration, using the self-consistent version of the Extended Theory of Finite Fermi Systems. It was found that the phonon contribution to the pygmy-dipole resonance and radiative neutron capture cross section is increased with the (N - Z) difference growth. The results show that the self-consistent nuclear structure calculations are important for unstable nuclei, where phenomenological approaches do not work.

Avdeenkov, A. V. [Stellenbosch Institute of Advanced Study, National Institute for Theoretical Physics (South Africa); Goriely, S. [Institute d'Astronomie et d'Astrophysique (Belgium); Kamerdzhiev, S. P. [Institute of Physics and Power Engineering (Russian Federation)

2010-07-15

183

Impact parameter dependence of electron capture in slow O5+ + He collisions  

NASA Astrophysics Data System (ADS)

Angular distributions of recoiling He2+ and He+ ions following collisions of slow O5+ ions and He atoms were measured, for projectile energies in the range 100-2500 eV. The recoil ions were detected at angles from 20° to 130°. Two groups of peaks are clearly visible, corresponding to single and double electron capture. Highly energetic He2+ and He+ ions were observed at forward angles. It has already been shown in previous works on the C5+ and B5+ + He collisions that recoiling He+ targets mainly originate from a single electron capture on the n = 2 or 3 orbitals of the projectile, whereas He2+ ions are due to a double electron capture on 2ellnell'(n geq 2) configurations. The population of such configurations is confirmed by our model calculations based on classical kinematics equations. From this model, charge exchange probabilities P (b), where b is the impact parameter, were deduced for the explored projectile energies. To explain the large kinetic energies for recoil targets, we had to invoke electron capture processes under small impact parameter conditions (b < 1 au). At 2500 eV, while the capture events occurring at large impact parameters are not detected in the present measurements, electron capture in collisions at small impact parameters is evidenced. At the lowest projectile energy (100 eV) we have access to the whole range of impact parameters. The contribution of small impact parameters is shown to be dominant at this energy.

Sobocinski, P.; Rangama, J.; Chesnel, J.-Y.; Allio, G.; Hennecart, D.; Laurent, G.; Adoui, L.; Cassimi, A.; Dubois, S.; James, O.; Martina, D.; Spicq, A.; Bremer, J.-H.; Dubois, A.; Frémont, F.

2003-04-01

184

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

SciTech Connect

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

Klepp, J.; Fally, M. [Faculty of Physics, University of Vienna, 1090 Wien (Austria); Tomita, Y. [Department of Engineering Science, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182 (Japan); Pruner, C. [Department of Materials Science and Physics, University of Salzburg, 5020 Salzburg (Austria); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

2012-10-08

185

Thermal Neutron Capture Cross Sections Of The Palladium Isotopes  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

186

Thermal Neutron Capture Cross Section of Carbon13  

Microsoft Academic Search

The thermal neutron capture cross section of C13 has been determined from the amount of C14 formed in pile-irradiated samples of graphite, barium carbonate, and carbon dioxide. Because of the impurity reaction, N14(n, p)C14, of comparatively high cross section, the results were consistent only when samples were used which were enriched in C13. The average isotopic cross section determined for

G. R. Hennig

1954-01-01

187

Radiative capture of thermal neutrons by ³He  

Microsoft Academic Search

An experimental and theoretical study of the radiative capture of thermal neutrons by ³He is reported. The measurements were made by the time-of-flight method in the IBR-30 pulsed reactor with use of a ³He gas target and NaI(Tl) detector. Calculations of the effective cross section of the (n..gamma..) reaction with emission of magnetic dipole radiation were made with use of

V. P. Alfimenkov; S. B. Borzakov; G. G. Bunatyan; J. Wierzbicki; L. B. Pikelner; E. I. Sharapov

1980-01-01

188

Neutron-capture gamma rays below 40 keV  

NASA Astrophysics Data System (ADS)

A review of neutron-capture gamma ray measurements below 40 keV is given and experimental methods are discussed. New experiments with a Si(Li) detector have been performed. Energies and absolute intensities of low energy (n, ?) transitions in 28Al, 40K, 52V, 128I, 134Cs, 160Tb, 166Ho, 170Tm, 176Lu, 182Ta, 192Ir, 198Au and 233Th are presented. These new results can serve calibration purposes and provide nuclear structure information.

Durner, P.; von Egidy, T.; Hartmann, F. J.

1989-06-01

189

Stellar neutron capture cross sections of the tin isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 114Sn, 115Sn, 116Sn, 117Sn, 118Sn, and 120Sn 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 using a pulsed proton beam. Capture events were registered with the Karlsruhe 4? barium fluoride detector. The experiment was complicated by the small (n,?) cross sections of the proton magic tin isotopes and by the comparably low enrichment of the rare isotopes 114Sn and 115Sn. Despite significant corrections for capture of scattered neutrons and for isotopic impurities, the high efficiency and the spectroscopic quality of the BaF2 detector allowed the determination of the cross-section ratios with overall uncertainties of 1-2 %, five times smaller compared to existing data. Based on these results, Maxwellian averaged (n,?) cross sections were calculated for thermal energies between kT=10 and 100 keV. These data are used for a discussion of the solar tin abundance and for an improved determination of the isotopic s- and r-process components.

Wisshak, K.; Voss, F.; Theis, Ch.; Käppeler, F.; Guber, K.; Kazakov, L.; Kornilov, N.; Reffo, G.

1996-09-01

190

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

191

Neutron Capture Measurements on Tl-isotopes at DANCE  

NASA Astrophysics Data System (ADS)

The thallium isotopes play an important role in the s-process nucleosynthesis at the s-process endpoint. Furthermore, ^204Tl is one of few branch point isotopes in the endpoint region. The understanding of branch point isotopes provides modeling constraints on the temperatures during which the process takes place. The production of s-only ^204Pb is controlled entirely by ^204Tl. Measurements of the capture cross-sections of the stable Tl isotopes have recently been made using the DANCE 4-? array at LANSCE. This provides needed resonance information in the region as well as preparing the way for measurements of as yet unmeasured capture cross-section of the unstable ^204Tl. The neutron capture data for the stable isotopes as well as the plan for future measurements will be discussed.

Couture, A.; Bredeweg, T. A.; Esch, E.-I.; Jandel, M.; Haight, R. C.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.

2006-10-01

192

Neutron-induced gamma dose from a reactor beam filter for boron neutron capture therapy.  

PubMed

For the boron neutron capture therapy (NCT) of deep-seated metastatic melanoma, an epithermal (up to a few keV energy) neutron beam from a reactor horizontal facility could be useful if the inherent contamination from fast neutrons and gamma rays could be minimised. Calculations for ANSTO's 10 MW research reactor HIFAR have shown that, even though a filter material such as AlF3 attenuates the fast neutron dose, the beam quality improvement is counteracted by a relative increase in the gamma dose because of the gammas arising from neutron captures in the filter material, particularly the aluminium. The aluminium gammas, most of which arise from thermal neutron capture, are hard and cannot be attenuated by lead or bismuth without comparable attenuation of the epithermal neutron flux. Addition of an absorber such as 6Li to the AlF3 filter was investigated as a means of reducing the hard gamma dose, but the improvement in beam quality was small and at considerable cost to dose intensity. Dose characteristics calculations confirmed the superiority of a tangential beam over a radial beam with better results from an unfiltered tangential beam than from an AlF3 filter in a radial beam. This study showed conclusively that assessments of filter assemblies based on the effect of individual components on either the neutron or gamma dose in isolation are inadequate. In assessing any epithermal neutron filter, thermal neutron shield, and gamma shield combination, the total effect of each on the neutron, gamma, and boron-10 dose must be considered. PMID:2798318

Harrington, B V

193

Thermal neutron capture cross sections of the palladium isotopes  

NASA Astrophysics Data System (ADS)

Precise thermal neutron capture ?-ray cross sections ?? were measured for all elements with Z=1-83,90, and 92, except 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, ?0=???(GS) if the decay scheme is complete. The EGAF file contains partial ?-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 ?? values from EGAF and the total radiative neutron cross section ?0 is obtained. The ?0 values derived for the palladium isotopes agree well with previous measurements and were in several cases more precise. Complementary use of ?-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.

Krti?ka, M.; Firestone, R. B.; McNabb, D. P.; Sleaford, B.; Agvaanluvsan, U.; Belgya, T.; Revay, Z. S.

2008-05-01

194

Neutron capture cross section on Lu isotopes at DANCE  

SciTech Connect

The DANCE (Detector for Advanced Neutron Capture Experiments) array at the LANSCE spallation neutron source in Los Alamos has been used to measure neutron capture cross sections for {sup 175}Lu and {sup 176}Lu with neutron energies from thermal up to 100 keV. Both isotopes are of current interest for the s-process nucleosynthesis. {sup 175}Lu is an important waiting-point in the s-process and {sup 176}Lu is a sensitive s-process thermometer. Three targets were used to perform these measurements. One was a natural Lu foil of 31 mg/cm{sup 2} and the other two were isotopically enriched targets of {sup 175}Lu (99.8%, {approx}1 mg/cm{sup 2} electro-deposited on Ti) and {sup 176}Lu (99.9%, {approx}1 mg/cm{sup 2} mass separator deposited on aluminized mylar). The data analysis is in progress. Preliminary cross sections have been obtained by normalizing the data to the known thermal cross section. A comparison of these data with recent experimental data of K. Wisshak et al. and the evaluated data of ENDF B-VII will be presented.

Couture, Aaron Joseph [Los Alamos National Laboratory; Roig, Olivier [CEA

2008-01-01

195

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

196

High-current electrostatic accelerator for boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

197

Measurements of keV-Neutron Capture Cross Sections and Capture Gamma-Ray Spectra of Se  

Microsoft Academic Search

The neutron capture cross sections and capture ?-ray spectra of Se were measured in a region from 15 to 100 keV and at around 510 keV. A neutron time-of-flight method was used with a ns-pulsed neutron source based on the Li(p,n) Be reaction and with a large anti-Compton NaI(Tl) ?-ray spectrometer. A pulse-height weighting technique was applied to the observed

So KAMADA; Masayuki IGASHIRA; Tatsuya KATABUCHI; Motoharu MIZUMOTO

2010-01-01

198

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

SciTech Connect

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

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

1989-01-01

199

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

200

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments  

SciTech Connect

The focus of this work is to determine resonance parameters for stable hafnium isotopes in the 0.005-200 eV region, with special emphasis on the overlapping {sup 176}Hf and {sup 178}Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically-enriched liquid samples. The liquid samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. Resonance integrals were calculated along with errors for each hafnium isotope using the NJOY [1] and INTER [2] codes. The isotopic resonance integrals calculated were significantly different than previously published values; however the calculated elemental hafnium resonance integral changed very little.

MJ Trbovich; DP Barry; RE Slovacck; Y Danon; RC Block; JA Burke; NJ Drindak; G Leinweber; RV Ballad

2004-10-13

201

Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments  

SciTech Connect

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

Trbovich, Michael J.; Barry, Devin P.; Burke, John A.; Drindak, Noel J.; Leinweber, Greg; Ballad, Robert V. [Lockheed Martin Corporation, P.O. Box 1072, Schenectady, New York 12301-1072 (United States); Slovacek, Rudy E.; Danon, Yaron; Block, Robert C. [Rensselaer Polytechnic Institute, Mechanical, Aerospace and Nuclear Engineering Department, Troy, New York 12180-3590 (United States)

2005-05-24

202

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

203

Reducing Uncertainty of Neutron Capture Reaction Calculations for Stellar Nucleosynthesis  

NASA Astrophysics Data System (ADS)

Astrophysicists believe that all elements on Earth are derived from nucleosynthesis in stars, a process of creating new atomic nuclei from neutrons and protons that already exist. While one ultimate goal is to see the actual distribution of elements in stars line up with experimental results, thereby supporting the hypothesis, many necessary reaction rates cannot be measured empirically and thus we must rely on theoretical calculations to come up with data. Neutron capture reactions play a big role in nucleosynthesis, and the statistical Hauser-Feshbach model is often adopted to calculate the neutron capture rates. My objective is to reduce the uncertainty of the calculations by adjusting different parameters, such as the gamma-ray strength and the level densities. For a certain set of nuclides for which Maxwellian Averaged Cross Sections (MACS) have been experimentally determined, I found better descriptions of the gamma strength function and the level density parameters that well fit the experimental MACS values. By continuing to adjust parameters to make the calculation results align with experimental values, we expect the calculation will become more accurate so that we can extrapolate and calculate quantities that cannot be measured.

Little, Hannah; Kawano, Toshihiko; Bertolli, Michael

2012-10-01

204

Monte Carlo simulation of biological effects of boron neutron capture irradiation with d(14)+Be neutrons in vitro  

Microsoft Academic Search

It was shown that radiation effects in tumor cells treated with fast neutrons may be increased by the neutron capture reaction ¹°B(n,α)⁷Li. The classic approach for macroscopic dosimetry in fast-neutron therapy cannot be applied to the dose in boron neutron capture therapy (BNCT). The effectiveness of BNCT in killing tumor cells depends on the number of ¹°B atoms delivered to

F. Poeller; W. Sauerwein

1995-01-01

205

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

Microsoft Academic Search

The Detector for Advanced Neutron Capture Experiments (DANCE) is a 162-element 4pi 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

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

2005-01-01

206

Contribution of neutron-capture reactions to observed tungsten isotopic ratios  

Microsoft Academic Search

To study whether tungsten isotopic ratios observed in terrestrial samples relative to W ratios in an iron meteorite could be made by neutron-capture reactions in the iron meteorite, the fluxes of thermal and epithermal neutrons in a large iron meteoroid, Toluca, were calculated using Monte Carlo particle production and transport codes. Peak neutron-capture rates on W isotopes were calculated to

Jozef Masarik

1997-01-01

207

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

SciTech Connect

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

Brugger, R.; Kunze, J.

1991-05-01

208

Thermal neutron capture cross section of {sup 74}Ge  

SciTech Connect

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

Meierhofer, G.; Grabmayr, P.; Jochum, J.; Kudejova, P.; Canella, L.; Jolie, J. [Kepler Center for Astro and Particle Physics, Universitaet Tuebingen, D-72076 Tuebingen (Germany); Forschungs-Neutronenquelle Heinz Maier-Leibnitz FRM II, Technische Universitaet Muenchen, D-85747 Garching (Germany); Institut fuer Radiochemie, Technische Universitaet Muenchen, D-85748 Garching (Germany); Institut fuer Kernphysik, Universitaet zu Koeln, D-50937 Cologne (Germany)

2010-02-15

209

Physical Implications of RHESSI Neutron Capture-Line Measurements  

NASA Astrophysics Data System (ADS)

We report high spectral-resolution measurements of the 2.223 MeV neutron capture-line obtained with the Reuven Ramaty High Energy Spectroscopic Imager (RHESSI) from the 2002 July 23 solar flare. The measured time history is compared with predicted time histories calculated using a magnetic loop model with a magnetic field perpendicular to the solar surface at the fo otp oints. The derived constraints on the interacting-particle angular distribution imply that the particles suffered pitch-angle scattering during transport through the coronal portion of the loop. The photospheric 3 He/H ratio was not well-constrained, primarily due to uncertainties of the measured nuclear deexcitation-line flux used to represent the neutron-pro duction time history.

Murphy, R. J.; Share, G.H.; Hua, X.-M.; Liu, R.P.; Smith, D.M.; Schwartz, R.A.

2003-07-01

210

Thermal neutron captures on $d$ and $^3$He  

SciTech Connect

We report on a study of the nd and n3He radiative captures at thermal neutron energies, using wave functions obtained from either chiral or conventional two- and three-nucleon realistic potentials with the hyperspherical-harmonics method, and electromagnetic currents derived in chiral effective field theory up to one loop. The predicted nd and n3He cross sections are in good agreement with data, but exhibit a significant dependence on the input Hamiltonian. A comparison is also made between these and new results for the nd and n3He cross sections obtained in the conventional framework for both potentials and currents.

L. Girlanda, A. Kievsky, L.E. Marcucci, S. Pastore, R. Schiavilla, M. Viviani

2010-11-01

211

Parity violation in radiative neutron capture on the deuteron  

NASA Astrophysics Data System (ADS)

Parity-violating (PV) effects in neutron-deuteron radiative capture are studied using Desplanques, Donoghue, and Holstein (DDH) and effective field theory weak potentials. The values of PV effects are calculated using wave functions, obtained by solving three-body Faddeev equations in configuration space for realistic strong potentials. The relations between physical observables and low-energy constants are presented, and dependencies of the calculated PV effects on strong and weak potentials are discussed. The presented analysis shows the possible reason for the existing discrepancy in PV nuclear data analysis using the DDH approach and reveals a new opportunity to study short-range interactions in nuclei.

Song, Young-Ho; Lazauskas, Rimantas; Gudkov, Vladimir

2012-10-01

212

Energy dependence of angular momentum capture states in charge exchange collisions between slow highly charged argon ions and argon neutrals  

Microsoft Academic Search

K -shell x-ray emission measurements of electron capture into Rydberg states of Ar17+ and Ar18+ ions are carried out as a function of collision energy in order to investigate the energy dependence of angular momentum capture states in slow charge exchange collisions. The highly charged ions are produced using an electron beam ion trap and extracted onto an external argon

F. I. Allen; C. Biedermann; R. Radtke; G. Fussmann; S. Fritzsche

2008-01-01

213

A classical model for multiple-electron capture in slow collisions of highly charged ions with atoms  

Microsoft Academic Search

A new version of the classical over-barrier model for multiple-electron capture in slow collisions between ions and atoms is described. This version accounts for the different ways in which an exchange of a certain number of electrons can occur. Since no adaptable parameter is involved, this model has predictive power. Model predictions of absolute multiple capture cross sections are compared

A. Niehaus

1986-01-01

214

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

215

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

216

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

217

Neutron diffraction measurements at the INES diffractometer using a neutron radiative capture based counting technique  

NASA Astrophysics Data System (ADS)

The global shortage of 3He gas is an issue to be addressed in neutron detection. In the context of the research and development activity related to the replacement of 3He for neutron counting systems, neutron diffraction measurements performed on the INES beam line at the ISIS pulsed spallation neutron source are presented. For these measurements two different neutron counting devices have been used: a 20 bar pressure squashed 3He tube and a Yttrium-Aluminum-Perovskite scintillation detector. The scintillation detector was coupled to a cadmium sheet that registers the prompt radiative capture gamma rays generated by the (n,?) nuclear reactions occurring in cadmium. The assessment of the scintillator based counting system was done by performing a Rietveld refinement analysis on the diffraction pattern from an ancient Japanese blade and comparing the results with those obtained by a 3He tube placed at the same angular position. The results obtained demonstrate the considerable potential of the proposed counting approach based on the radiative capture gamma rays at spallation neutron sources.

Festa, G.; Pietropaolo, A.; Grazzi, F.; Barzagli, E.; Scherillo, A.; Schooneveld, E. M.

2011-10-01

218

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

PubMed

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 7Li(p,n)7Be 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. PMID:2020734

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

1991-04-01

219

Carborane derivative development for boron neutron capture therapy. Final report  

SciTech Connect

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

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

1999-04-01

220

Neutron capture and stellar synthesis of heavy elements.  

PubMed

The neutron buildup processes of heavy-element synthesis in stars have left us a number of tantalizing nuclear clues to the early history of solarsystem material. Considerable illumination of our past history has been achieved through studying the correlations between abundance and neutroncapture cross section. Measurement of these cross sections required the development of new techniques for measuring time of flight of pulsed neutron beams. A clear conclusion is that many of our heavy elements were produced inside stars, which can be thought of as giant fast reactors. Extensions of these capture studies have given a clearer picture of additional. violent processes which produced some heavy elements, particularly thorium and uranium. In addition, the correlations have been used for obtaining an independent measure of the time that has elapsed since the solar-system material was synthesized. Finally, data on capture cross section relative to abundance will enable us to determine rather accurately the solar-system abundances of gaseous, volatile, and highly segregated elements. PMID:17774043

Gibbons, J H; Macklin, R L

1967-05-26

221

Thermal-neutron capture gamma-rays. Volume 1  

SciTech Connect

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

Tuli, J.K. [National Nuclear Data Center, Upton, NY (United States)

1997-05-01

222

Thermal-neutron capture gamma-rays. Volume 2  

SciTech Connect

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

Tuli, J.K. [National Nuclear Data Center, Upton, NY (United States)

1997-05-01

223

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

224

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

225

A SLOW AND FAST NEUTRON SCINTILLATION COUNT-RATE AND DOSE-RATE METER  

Microsoft Academic Search

A compact, scintillation, transistorized slow and fast neutron count-; rate and dose-ratc portable instrument was developed. The basic instrument ; weighs approximately six pounds without moderator. A spherical 10inch diameter ; paraffin moderator weighing 15 pounds is used with the instrument for fast ; neutron dose-rate-de terminations. A spherical polyethylene, 10-inch diameter ; moderator may also be used. The polyethylene

1958-01-01

226

Neutron capture in (sup 148,150)Sm: A sensitive probe of the s-process neutron density.  

National Technical Information Service (NTIS)

The neutron capture cross sections of (sup 147,148,149,150,152)Sm were measured in the energy range from 3 to 225 keV at the Karlsruhe Van de Graaff accelerator using gold as a standard. Maxwellian averaged neutron capture cross sections were calculated f...

K. Wisshak K. Guber F. Voss F. Kaeppeler G. Reffo

1992-01-01

227

Boron neutron capture therapy for recurrent high-grade meningiomas.  

PubMed

Object Similar to glioblastomas, high-grade meningiomas are difficult pathologies to control. In this study, the authors used boron neutron capture therapy (BNCT), a tumor-selective intensive particle radiation modality, to treat high-grade meningioma. Methods From June 2005 to September 2011, BNCT was applied 28 times in 20 cases of recurrent high-grade meningioma. All patients had previously undergone intensive treatments such as repetitive surgeries and multiple sessions of radiation therapy. Fluorine-18-labeled boronophenylalanine ((18)F-BPA) PET was performed before BNCT in 19 of the 20 cases; BPA is itself a therapeutic compound. Compound uptake, tumor shrinkage, long-term control rate including survival time, and failure pattern of the treated patients were all evaluated. Results Eighteen of 19 cases studied using (18)F-BPA PET showed good BPA uptake, with ratios of tumor to normal brain greater than 2.7. These ratios indicated the likely effects of BNCT prior to neutron irradiation. The original tumor sizes were between 4.3 cm(3) and 109 cm(3). A mean tumor volume reduction of 64.5% was obtained after BNCT within just 2 months. The median follow-up duration was 13 months. Six patients are still alive; at present, the median survival times after BNCT and diagnosis are 14.1 months (95% CI 8.6-40.4 months) and 45.7 months (95% CI 32.4-70.7 months), respectively. Clinical symptoms before BNCT, such as hemiparesis and facial pain, were improved after BNCT in symptomatic cases. Systemic metastasis, intracranial distant recurrence outside the radiation field, CSF dissemination, and local tumor progression were observed in 6, 7, 3, and 3 cases, respectively, during the clinical course. Apparent pseudoprogression was observed in at least 3 cases. Symptomatic radiation injuries occurred in 6 cases, and were controllable in all but 1 case. Conclusions Boron neutron capture therapy may be especially effective in cases of high-grade meningioma. PMID:23808536

Kawabata, Shinji; Hiramatsu, Ryo; Kuroiwa, Toshihiko; Ono, Koji; Miyatake, Shin-Ichi

2013-06-28

228

Filter, collimator and moderating material to achieve boron neutron capture enhanced fast neutron therapy.  

PubMed

The combination of fast neutron therapy and boron neutron capture therapy is currently being studied as a possible treatment for some radio-resistant brain tumours. In an attempt to design a boron-enhanced fast neutron therapy beam for the Fermilab Fast Neutron Therapy Facility, the use of moderating material surrounding the patient's head has been investigated. Graphite, polyethylene, water and heavy water were studied as moderating materials, using MCNP. The use of tungsten, iron, lead and bismuth as materials for a small filter and collimator near the patient's head was investigated. Calculations showed that a filter and collimator made of tungsten with a graphite moderator was capable of producing a dose enhancement of 17.3 +/- 0.6% for a 100 microg g(-1) loading of 10B for a 5.6 cm diameter beam while delivering 1.5 Gy in 7 min. PMID:16604680

Sweezy, J; Hertel, Nolan; Lennox, Arlene

2005-01-01

229

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

230

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

SciTech Connect

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

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

1998-06-01

231

Advances in atomic data for neutron-capture elements  

NASA Astrophysics Data System (ADS)

Neutron(n)-capture elements (atomic number Z > 30), which can be produced in planetary nebula (PN) progenitor stars via s-process nucleosynthesis, have been detected in nearly 100 PNe. This demonstrates that nebular spectroscopy is a potentially powerful tool for studying the production and chemical evolution of trans-iron elements. However, significant challenges must be addressed before this goal can be achieved. One of the most substantial hurdles is the lack of atomic data for n-capture elements, particularly that needed to solve for their ionization equilibrium (and hence to convert ionic abundances to elemental abundances). To address this need, we have computed photoionization cross sections and radiative and dielectronic recombination rate coefficients for the first six ions of Se and Kr. The calculations were benchmarked against experimental photoionization cross section measurements. In addition, we computed charge transfer (CT) rate coefficients for ions of six n-capture elements. These efforts will enable the accurate determination of nebular Se and Kr abundances, allowing robust investigations of s-process enrichments in PNe.

Sterling, Nicholas C.; Witthoeft, Michael C.; Esteves, David A.; Stancil, Phillip C.; Kilcoyne, A. L. David; Bilodeau, Rene C.; Aguilar, Alejandro

2012-08-01

232

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

233

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

234

Neutron Tube Design Study for Boron Neutron Capture TherapyApplication  

SciTech Connect

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

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

1998-01-04

235

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

NASA Astrophysics Data System (ADS)

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

Dinerstein, H.

236

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

237

Radiative capture of thermal neutrons by /sup 3/He  

SciTech Connect

An experimental and theoretical study of the radiative capture of thermal neutrons by /sup 3/He is reported. The measurements were made by the time-of-flight method in the IBR-30 pulsed reactor with use of a /sup 3/He gas target and NaI(Tl) detector. Calculations of the effective cross section of the (n..gamma..) reaction with emission of magnetic dipole radiation were made with use of Gaussian wave functions of the ground states of /sup 3/He and /sup 4/He. From comparison of the experimental and theoretical results an estimate is obtained for the admixture of the ''mixed-symmetry'' state of /sup 4/He nucleus.

Alfimenkov, V.P.; Borzakov, S.B.; Bunatyan, G.G.; Wierzbicki, J.; Pikel'ner, L.B.; Sharapov, E.I.

1980-01-01

238

Boron neutron capture therapy for the prevention of restenosis  

SciTech Connect

The potential application of boron neutron capture therapy (BNCT) for the prevention of restenosis following angioplasty is under investigation at Massachusetts Institute of Technology`s Laboratory for Accelerator Beam Applications. The process of Percutaneous transluminal coronary angioplasty involves the insertion of a balloon dilation catheter into the occluded artery. The balloon is then inflated for several minutes to dilate the artery. The blockage is decreased, and blood flow through the artery is improved. This procedure is, initially, very successful. However, 30 to 60% of patients treated also show restenosis within 6 months. Although many physiological processes may contribute to restenosis, the primary mechanism is thought to be abnormal proliferation of the smooth muscle cells in the treated artery.

Yanch, J.C.; Delfaus, M.L. [Massachusetts Institute of Technology, Cambridge, MA (United States)

1997-12-01

239

PGNAA of human arthritic synovium for boron neutron capture synovectomy  

SciTech Connect

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

Binello, E.; Yanch, J.C. [Massashucetts Institute of Technology, Cambridge, MA (United States); Shortkroff, S. [Brigham and Women`s Hospital, Boston, MA (United States)

1997-12-01

240

Thick beryllium target as an epithermal neutron source for neutron capture therapy.  

PubMed

Accelerator-based intense epithermal neutron sources for Neutron Capture Therapy (NCT) have been considered as an alternative to nuclear reactors. Lithium (Li) has generally received the widest attention for this application, since the threshold energy is low and neutron yield is high. Because of the poor thermal and chemical properties of Li and the need for heat removal in the target, the design of Li targets has been quite difficult. Beryllium (Be) has been thought of as an alternative target because of its good thermal and chemical properties and reasonable neutron yield. However, in order to have a neutron yield comparable to that of a thick Li target bombarded with 2.5 MeV protons, the proton energy required for a thick Be target must be approaching 4 MeV. Consequently, the neutrons emitted are more energetic. In addition, a significant amount of high-energy gamma rays, which is undesirable, will occur when Be is bombarded with low-energy protons. Regardless of the more energetic neutrons and additional gamma rays, in this paper it is shown that it is possible to develop a high-quality and high-intensity epithermal neutron beam based on a thick Be target for NCT treatment. For a fixed proton current, the optimal Be-target-based beam (with 4-MeV protons) can produce a neutron beam, with both quality and intensity slightly better than those produced by the optimal Li-target-based beam (with 2.5-MeV protons). The single-session NCT treatment time for the optimal Be-target-based beam is estimated to be 88 min for a proton current of 50 mA.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7869996

Wang, C K; Moore, B R

1994-10-01

241

Gadolinium as an element for neutron capture therapy  

SciTech Connect

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

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

1992-12-31

242

Gadolinium as an element for neutron capture therapy  

SciTech Connect

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

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

1992-01-01

243

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

PubMed

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

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

2012-10-24

244

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

245

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

PubMed

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. PMID:10718140

Nigg, D W; Wemple, C A; Risler, R; Hartwell, J K; Harker, Y D; Laramore, G E

2000-02-01

246

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); Wemple, Charles A. [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); Hartwell, John K. [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); Laramore, George E. [University of Washington, Department of Radiation Oncology, P.O. Box 356043, Seattle, Washington 98195 (United States)

2000-02-01

247

Using 171,173Yb(d,p?) to Benchmark a Surrogate Reaction for Neutron Capture  

NASA Astrophysics Data System (ADS)

The 171,173Yb(d,p?) 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,?) cross section ratios within 15%.

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

2009-03-01

248

Diffraction of slow neutrons by holographic SiO{sub 2} nanoparticle-polymer composite gratings  

SciTech Connect

Diffraction experiments with holographic gratings recorded in SiO{sub 2} nanoparticle-polymer composites have been carried out with slow neutrons. The influence of parameters such as nanoparticle concentration, grating thickness, and grating spacing on the neutron-optical properties of such materials has been tested. Decay of the grating structure along the sample depth due to disturbance of the recording process becomes an issue at grating thicknesses of about 100 microns and larger. This limits the achievable diffraction efficiency for neutrons. As a solution to this problem, the Pendelloesung interference effect in holographic gratings has been exploited to reach a diffraction efficiency of 83% for very cold neutrons.

Klepp, J.; Fally, M. [University of Vienna, Faculty of Physics, A-1090 Wien (Austria); Pruner, C. [University of Salzburg, Department of Materials Science and Physics, A-5020 Salzburg (Austria); Tomita, Y. [University of Electro-Communications, Department of Engineering Science, 1-5-1 Chofugaoka, Chofu, Tokyo 182 (Japan); Plonka-Spehr, C. [University of Mainz, Institute for Nuclear Chemistry, D-55128 Mainz (Germany); Geltenbort, P.; Ivanov, S.; Manzin, G. [Institut Laue Langevin, Boite Postale 156, F-38042 Grenoble Cedex 9 (France); Andersen, K. H. [Institut Laue Langevin, Boite Postale 156, F-38042 Grenoble Cedex 9 (France); European Spallation Source, P.O. Box 176, S-22100 Lund (Sweden); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Ellabban, M. A. [Taibah University, Faculty of Science, Physics Department, 30002 Madinah (Saudi Arabia)

2011-07-15

249

Characterization of the Gamma Response of a Cadmium Capture-gated Neutron Spectrometer  

NASA Astrophysics Data System (ADS)

We have studied the gamma response of a newly developed capture-gated neutron spectrometer. Such spectrometers detect a dual signal from incoming neutrons, allowing for differentiation between other particles, such as gamma rays. The neutron provides a primary light pulse in either plastic or liquid scintillator through neutron-proton collisions. A capture material then delivers a second pulse as the moderated neutron captures in the intended material, which then de-excites with the release of gamma energy. The presented spectrometer alternates one centimeter thick plastic scintillators with sheets of cadmium inserted in between for neutron capture. The neutron capture in cadmium offers a release of gamma energy ˜ 9 MeV. To verify that the interaction was caused by a neutron, the response functions of both events must be well known. Due to the prior existence of many capture-gated neutron spectrometers, the proton recoil pulse has already been studied, but the capture pulse is unique to each spectrometer and must be measured. Experimental results agree with theoretical Monte-Carlo code, both suggesting that the optics and geometry of the spectrometer play a large role in its efficiency. Results prove promising for the efficiency of the spectrometer.

Hogan, Nathaniel; Rees, Lawrence; Czirr, Bart; Bastola, Suraj

2010-10-01

250

The Neutron-Proton Radiative Capture Analyzing Power.  

NASA Astrophysics Data System (ADS)

We have used a beam of polarized neutrons to measure the analyzing power, or left-right asymmetry in the yield of gamma rays, for neutron-proton radiative capture at (theta)(,lab)(' )= 90(DEGREES) and two energies: at E(,n) = 6.0 MeV the neutrons were produced by the reaction ('3)H(p,n)('3)He,(' )while at E(,n) = 13.43 MeV the reaction ('2)H(d,n)('3)He was employed.(, )The hydrogen target was a cylinder of NE213 liquid scintillator, which also served to detect the recoil deuterons. Gamma rays were detected in a large NaI crystal. The neutron polarization was determined by measuring the polarization of the charged particles and using known polarization transfer coefficients.('1,2). The best theoretical calculations available('3) combine classical impulse calculations('4) with meson exchange currents. The measured analyzing power at E(,n) = 6.0 MeV, A = -0.0681 (+OR-) 0.0274, is significantly less negative than these calculations. The measured analyzing power at E(,n) = 13.43 MeV, A = -0.0954 (+OR-) 0.0268, is also less negative than these calculations, but is consistent with the theoretical value within the statistical uncertainty. This experiment is consistent with previous experiments('5 -8) measuring the polarization of neutrons produced by the inverse reaction, deuteron photodisintegration, between E(,(gamma)) = 5.0 and 15.0 MeV. By far the majority of the data points are less negative than the theoretical prediction. Calculations using different nucleon-nucleon. potentials do not change the results significantly. We conclude (a) the uncertainties in some of the experiments have been underestimated; and (b) the theoretical calculations are lacking in some respect. ('1) R. C. Haight, et. al., Phys. Rev. C5 (1972) 1826. ('2) P. W. Lisowski, et. al., Nucl. Phys. A242 (1975) 298. ('3) E. Hadjimichael, Phys. Lett. 46B (1973) 147. ('4) F. Partovi, Annals of Physics 27 (1964) 79. ('5) W. Bertozzi, et. al., Phys. Rev. Lett. 10 (1963) 106. ('6) L. J. Drooks, PhD thesis, Yale University, (1976). ('7) R. J. Holt, et. al., Phys. Rev. Lett. 50 (1983) 577. ('8) R. Nath, et. al., Nucl. Phys. A194 (1972) 49.

Soderstrum, John Preston

251

Neutron resonance parameters and thermal-neutron capture by [sup 43]Ca  

SciTech Connect

Neutron transmission measurements have been carried out on a small sample (205.9 mg) of CaCO[sub 3] with a [sup 43]Ca enrichment of 49.1%. The parameters (spins and neutron widths) of eight resonances below the neutron energy of 20 keV have been determined. This information was combined with a previously measured thermal-neutron coherent scattering length to deduce the separate scattering lengths for the two spin states present in [ital s]-wave scattering. These values were used to calculate the direct (potential + valence) capture cross sections of the primary electric-dipole gamma transitions in [sup 44]Ca using optical-model potentials with physically realistic parameters. For those states below 6.2 MeV for which the [ital l]=1 ([ital d],[ital p]) spectroscopic factors are known, the experimental cross sections are consistent with our current understanding of the direct and compound-nuclear capture processes. The processes leading to states above 6.2 MeV require further experimental and theoretical studies.

Moxon, M.C.; Harvey, J.A.; Raman, S. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)); Lynn, J.E. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Ratynski, W. (Soltan Institute of Nuclear Physics, Otwock-Swierk (Poland))

1993-08-01

252

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

PubMed

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

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

2004-11-01

253

GE PETtrace cyclotron as a neutron source for boron neutron capture therapy.  

PubMed

This paper discusses the use of a General Electric PETtrace cyclotron as a neutron source for boron neutron capture therapy. In particular, the standard PETtrace (18)O target is considered. The resulting dose from the neutrons emitted from the target is evaluated using the Monte Carlo radiation transport code MCNP at different depths in a brain phantom. MCNP-simulated results are presented at 1, 2, 3, 4, 5, 6, 7, and 8 cm depth inside this brain phantom. Results showed that using a PETtrace cyclotron in the current configuration allows treating tumors at a depth of up to 4 cm with reasonable treatment times. Further increase of a beam current should significantly improve the treatment time and allow treating tumors at greater depths. PMID:15308192

Bosko, A; Zhilchenkov, D; Reece, W D

2004-11-01

254

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

255

The Chemical Evolution in the Solar Vicinity and the Nucleosynthesis of Neutron Capture Elements  

NASA Astrophysics Data System (ADS)

We propose an explanation for the considerable scatter of the abundances of neutron capture elements observed in low metallicity stars in the solar vicinity, compared to the small star to star scatter observed for the ?-elements. We have developed a stochastic chemical evolution model, in which the main assumption is a random formation of new stars, subject to the condition that the cumulative mass distribution follows a given initial mass function. With our model we are able to reproduce the different spreads of neutron capture elements and ?-elements in low metallicity stars. The reason for different observed spread in neutron capture elements and ?-elements resides in the random birth of stars coupled with different stellar mass ranges from which ?-elements and neutron capture elements originate. In particular, the site of production of ?-elements is the whole range of the massive stars, from 10 to 8OMsolar whereas the mass range of production for neutron capture elements lies between 12 and 30Msolar.

Cescutti, G.; Matteucci, F.; François, P.

2008-04-01

256

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

257

Mn, Cu, and Zn abundances in barium stars and their correlations with neutron capture elements  

Microsoft Academic Search

Barium stars are optimal sites for studying the correlations between the neutron-capture elements and other species that may be depleted or enhanced, because they act as neutron seeds or poisons during the operation of the s-process. These data are necessary to help constrain the modeling of the neutron-capture paths and explain the s-process abundance curve of the solar system. Chemical

D. M. Allen; G. F. Porto de Mello

2011-01-01

258

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

259

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

260

Measurement of the neutron-neutron scattering length using the {pi}{sup -}d capture reaction  

SciTech Connect

We have determined a value for the {sup 1}S{sub 0} neutron-neutron scattering length (a{sub nn}) from high-precision measurements of time-of-flight spectra of neutrons from the {sup 2}H({pi}{sup -},n {gamma}) n capture reaction. The measurements were done at the Los Alamos Meson Physics Facility by the E1286 Collaboration. The high spatial resolution of our {gamma}-ray detector enabled us to make a detailed assessment of the systematic uncertainties in our techniques. The value obtained in the present work is a{sub nn}=-18.63{+-}0.10 (statistical) {+-} 0.44 (systematic) {+-} 0.30 (theoretical) fm. This result is consistent with previous determinations of a{sub nn} from the {pi}{sup -}d capture reaction. We found that the analysis of the data with calculations that use a relativistic phase-space factor gives a more negative value for a{sub nn} by 0.33 fm over the analysis done using a nonrelativistic phase-space factor. Combining the present result with the previous ones from {pi}{sup -}d capture gives a{sub nn}=-18.63{+-}0.27(expt){+-}0.30 fm (theory). For the first time the combined statistical and systematic experimental uncertainty in a{sub nn} is smaller than the theoretical uncertainty and comparable to the uncertainty in the proton-proton {sup 1}S{sub 0} scattering length (a{sub pp}). This average value of a{sub nn} when corrected for the magnetic-moment interaction of the two neutrons becomes -18.9 {+-} 0.4 fm, which is 1.6 {+-} 0.5 fm different from the recommended value of a{sub pp}, thereby confirming charge symmetry breaking at the 1% confidence level.

Chen, Q.; Howell, C. R.; Kiser, M. R.; Roper, C. D.; Salinas, F.; Setze, H. R.; Tornow, W.; Walter, R. L. [Duke University and Triangle Universities Nuclear Laboratory, Durham, North Carolina (United States); Carman, T. S. [Lawrence Livermore National Laboratory, Livermore, California (United States); Gibbs, W. R. [New Mexico State University, Las Cruces, New Mexico (United States); Gibson, B. F.; Morris, C.; Obst, A.; Sterbenz, S.; Whitton, M. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Hussein, A. [University of Northern British Columbia (Canada); Mertens, G. [University of Tuebingen, Tuebingen (Germany); Moore, C. F.; Whiteley, C. R. [University of Texas, Austin, Texas (United States); Pasyuk, E. [Joint Institute of Nuclear Research, Dubna (Russian Federation)] (and others)

2008-05-15

261

A simple method for the analysis of neutron resonance capture spectra  

Microsoft Academic Search

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

Martijn C. Clarijs; Victor R. Bom; Hans Postma; Carel W. E. van Eijk

262

A simple method for the analysis of neutron resonance capture spectra  

Microsoft Academic Search

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

Martijn C. Clarijs; Victor R. Bom; Carel W. E. van Eijk

2009-01-01

263

A simple method for the analysis of neutron resonance capture spectra  

Microsoft Academic Search

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

Martijn C. Clarijs; Victor R. Bom; Carel W. E. van Eijk

2009-01-01

264

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

Microsoft Academic Search

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

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

2004-01-01

265

Capture Cross-Sections for Thermal Neutrons in Thorium, Lead and Uranium 238  

Microsoft Academic Search

EXPERIMENTS on the processes arising in thorium under neutron bombardment have shown that nuclear fission is induced only by fast neutrons of energies of about 2 Mev. or more. There exists also a radiative capture process producing an isotope of thorium (Th 233) of 26 min. half-life; this process has a resonance character with a large contribution from thermal neutrons1.

Lise Meitner

1940-01-01

266

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

267

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

268

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

269

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

PubMed

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

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

2003-08-01

270

Determination of Sensitivity of the SNM-14 Slow Neutron Counter with a Combined Moderator at the 14.2 MeV Neutron Energy.  

National Technical Information Service (NTIS)

The sensitivity of the SNM-14 slow neutron counter a combined moderator at the 14.2 MeV neutron energy has been experimentally determined. The 14.2 MeV neutrons were produced by means of a neutron laser generator using the T(d, n) sup 4 He reaction. The m...

V. N. Buchnev M. M. Komochkov A. M. Kucher Y. V. Mokrov N. V. Zubkov

1985-01-01

271

Boron neutron capture therapy of glioblastoma multiforme using the p- boronophenylalanine-fructose complex and epithermal neutrons.  

National Technical Information Service (NTIS)

The amino acid analogue p-boronophenylalanine (BPA) is under investigation as a neutron capture agent for BNCT of glioblastoma multiforme. A series of patients undergoing surgical removal of tumor received BPA orally as the free amino acid. Favorable tumo...

J. A. Coderre A. D. Chanana D. D. Joel H. B. Liu D. N. Slatkin

1994-01-01

272

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

273

Possible Use of a Spallation Neutron Source for Neutron Capture Therapy with Epithermal Neutrons.  

National Technical Information Service (NTIS)

Spallation is induced in a heavy material by 72 MeV protons. The hereby produced neutrons with essentially an evaporation spectrum with a peak energy of less than 2 MeV are moderated in two steps, first in iron, and then in carbon. Results from neutron fl...

E. Grusell H. Conde B. Larsson T. Roennqvist O. Sornsuntisook

1989-01-01

274

Use of Neutron Transfer Reactions to Indirectly Determine Neutron Capture Cross Sections on Neutron-Rich Nuclei  

SciTech Connect

{sup 14}C(n,gamma){sup 15}C is being used as a test case in the development of an indirect method to determine neutron capture cross sections on neutron-rich unstable nuclei at astrophysical energies. Our approach makes use of two reactions: one peripheral used to find the asymptotic normalization coefficient (ANC) and a second non-peripheral reaction to determine the spectroscopic factor. The ANC for {sup 15}C has been determined using a HI neutron transfer reaction with a 12 MeV/nucleon {sup 14}C beam on a {sup 13}C target. The spectroscopic factor will be determined using {sup 14}C(d,p) in forward kinematics with an incident deuteron energy of 60 MeV. Both experiments were performed using the MDM high-resolution spectrometer at Texas A and M University.

McCleskey, M.; Mukhamedzhanov, A. M.; Tribble, R. E.; Simmons, E.; Spiridon, A.; Banu, A.; Roeder, B.; Goldberg, V.; Trache, L.; Chen, X. F.; Lui, Y.-W. [Cyclotron Institute, Texas A and M University, College Station, TX 77843 (United States)

2010-03-01

275

Use of Neutron Transfer Reactions to Indirectly Determine Neutron Capture Cross Sections on Neutron-Rich Nuclei  

NASA Astrophysics Data System (ADS)

14C(n,?)15C is being used as a test case in the development of an indirect method to determine neutron capture cross sections on neutron-rich unstable nuclei at astrophysical energies. Our approach makes use of two reactions: one peripheral used to find the asymptotic normalization coefficient (ANC) and a second non-peripheral reaction to determine the spectroscopic factor. The ANC for 15C has been determined using a HI neutron transfer reaction with a 12 MeV/nucleon 14C beam on a 13C target. The spectroscopic factor will be determined using 14C(d,p) in forward kinematics with an incident deuteron energy of 60 MeV. Both experiments were performed using the MDM high-resolution spectrometer at Texas A&M University.

McCleskey, M.; Mukhamedzhanov, A. M.; Tribble, R. E.; Simmons, E.; Spiridon, A.; Banu, A.; Roeder, B.; Goldberg, V.; Trache, L.; Chen, X. F.; Lui, Y.-W.

2010-03-01

276

Use of Neutron Transfer Reactions to Indirectly Determine Neutron Capture Cross Sections on Neutron-Rich Nuclei  

NASA Astrophysics Data System (ADS)

14C(n,?)15C is being used as a test case in the development of an indirect method to determine neutron capture cross sections on neutron-rich unstable nuclei at astrophysical energies. Our approach makes use of two reactions: one peripheral used to find the asymptotic normalization coefficient (ANC) and a second non-peripheral reaction to determine the spectroscopic factor. The ANC for 15C has been determined using a HI neutron transfer reaction with a 12 MeV/nucleon 14C beam on a 13C target. The spectroscopic factor will be determined using 14C(d,p) in forward kinematics with an incident deuteron energy of 60 MeV. Both experiments were performed using the MDM high-resolution spectrometer at Texas A&M University.

McCleskey, M.; Mukhamedzhanov, A. M.; Tribble, R. E.; Simmons, E.; Spiridon, A.; Banu, A.; Roeder, B.; Goldberg, V.; Trache, L.; Chen, X. F.; Lui, Y.-W.

2010-11-01

277

Neutron capture therapy of a rat glioma using boronophenylalanine as a capture agent  

SciTech Connect

The purpose of the present study was to determine the efficacy of boron neutron capture therapy (BNCT) in treating the therapeutically refractory F98 glioma, using boronophenylalanine (BPA) as the capture agent. F98 glioma cells (10{sup 5}) were implanted stereotactically into the brains of Fischer rats and 15 days later the animals were injected intraperitoneally with 897 mg/kg of D,L-BPA. Between 3 and 9 h after administration blood and tumor boron concentrations exhibited monoexponential decay with half-lives (t{sub 1/2}) of 4.3 and 5.3 h, respectively. When 803 mg/kg of {sup 10}B-L-BPA was administered, the tumor {sup 10}B concentration was 29.4 {mu}g/g and tumor-to-blood and tumor-to-brain ratios were 3.5 and 3.9, respectively. Seven days after intracerebral implantation of 10{sup 5} F98 cells, BNCT was initiated at the Brookhaven Medical Research Reactor. The median survival time for irradiated controls (no BPA), which had received tumor physical doses of 1.7, 2.6, or 3.5 Gy, were 27, 33, and 38 days, respectively, compared to 24 days for untreated rats (P {le} 0.025-0.0001). The median survival time for BNCT-treated groups that had received 803 mg/kg of {sup 10}B-L-BPA 6 h prior to irradiation with total estimated tumor physical doses of 5.7, 8.6 and 11.5 Gy were 32, 37 and 59 days, respectively. Although the enhanced median survival times of two of the BNCT-treated groups (8.6 and 11.5 Gy) were significant compared to their matched irradiated controls (P {le} 0.0175-0.0277), all BNCT-treated animals died in less than 160 days. It remains to be determined whether better survival can be achieved using higher doses of BPA and neutrons to treat a tumor, which at this time cannot be cured by any therapeutic modality. 44 refs., 3 figs., 4 tabs.

Matalka, K.Z.; Barth, R.F.; Staubus, A.E.; Moeschberger, M.L. [Ohio State Univ., Columbus, OH (United States); Coderre, J.A. [Brookhaven National Lab., Upton, NY (United States)

1994-01-01

278

Role of neutron transfer and deformation effect in capture process at sub-barrier energies  

NASA Astrophysics Data System (ADS)

The roles of nuclear deformation and neutron transfer in sub-barrier capture process are studied within the quantum diffusion approach. The change of the deformations of colliding nuclei with neutron exchange can crucially influence the sub-barrier fusion. The sub-barrier capture reactions following the neutron pair transfer are used for the indirect study of neutron-neutron correlation in the surface region of nucleus. The strong surface enhancement of the neutron pairing in nuclei 48Ca, 64Ni, and 116,124,132Sn is demonstrated. Comparing the capture cross sections calculated without the breakup effect and experimental complete fusion cross sections, the breakup was analyzed in reactions with weakly bound projectiles 6,7,9Li and 9Be. A trend of a systematic behavior for the complete fusion suppression as a function of the target charge and bombarding energy is not achieved.

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

2012-12-01

279

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

SciTech Connect

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

Bortolussi, S.; Altieri, S. [Department of Nuclear and Theoretical Physics, University of Pavia, INFN Section of Pavia, via Bassi 6, 27100 Pavia (Italy)

2007-12-15

280

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

281

INTERIM REPORT ON A FAST-AND SLOW-NEUTRON SURVEY METER  

Microsoft Academic Search

An experimental model of a portable fast- and slowneutron survey meter ; was constructed and tested for use in estimating dose rate around nuclear ; reactors. The instrument contains proportional counters sensitive to fast or ; slow neutrons, At a tolerance flux of either, the instrument reads in the ; neighborhood of halfscale. The model case measures about 6 by

A. H. Redmond; E. J. Wesley; J. H. McQuoid

1957-01-01

282

Dance:. a 4? Barium Fluoride Detector for Measuring Neutron Capture on Unstable Nuclei  

NASA Astrophysics Data System (ADS)

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

Ullmann, J. L.; Haight, R. C.; Hunt, L.; Reifarth, R.; Rundberg, R. S.; Bredeweg, T. A.; Fowler, M. M.; Miller, G. G.; Wilhelmy, J. B.; Strottman, D. D.; Heil, M.; Käppeler, F.; Chamberlin, E. P.

2003-06-01

283

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

SciTech Connect

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

Ullmann, J. L. (John L.); Haight, Robert C.; Hunt, L. F. (Lloyd F.); Reifarth, R. (Rene); Rundberg, R. S. (Robert S.); Bredeweg, T. A. (Todd A); Fowler, Malcolm M.; Miller, G. G. (Geoffrey G.); Heil, M.; Käppeler, F. (Franz); Chamberlin, E. P. (Edwin P.)

2002-01-01

284

Monte Carlo methods of neutron beam design for neutron capture therapy at the MIT Research Reactor (MITR-II)  

Microsoft Academic Search

Monte Carlo methods of coupled neutron\\/photon transport are being used in the design of filtered beams for Neutron Capture Therapy (NCT). This method of beam analysis provides segregation of each individual dose component, and thereby facilitates beam optimization. The Monte Carlo method is discussed in some detail in relation to NCT epithermal beam design. Ideal neutron beams (i.e., plane-wave monoenergetic

S. D. Clement; J. R. Choi; R. G. Zamenhof; J. C. Yanch; O. K. Harling

1990-01-01

285

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

PubMed

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

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

2004-01-01

286

Depth distribution of boron determined by slow neutron induced lithium ion emission  

Microsoft Academic Search

Neutron Depth Profiling (NDP) has been established as a non-destructive technique to determine the near surface distribution of light elements, particularly boron. By analyzing the residual energy spectrum of the emitted particles of known initial energy as a result of nuclear capture within the target material, information about the site and amount of the reactions can be deduced. In the

Huaiyu H. Chen-Mayer; George P Lamaze

1998-01-01

287

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

SciTech Connect

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 and thermalize, and a photon field is generated from neutron capture in hydrogen. In this paper, a method to determine the doses from thermal and fast neutrons, photons, and the B-10([ital n],[alpha])Li-7 reaction is presented. The photon and fast neutron doses are measured with ionization chambers, in realistic phantoms, using the dual chamber technique. The thermal neutron flux is measured with gold foils using the cadmium difference technique; the thermal neutron and B-10 doses are determined by the kerma factor method. Representative results are presented for a unilateral irradiation of the head. Sources of error in the method as applied to BNCT dosimetry, and the uncertainties in the calculated doses are discussed.

Rogus, R.D.; Harling, O.K.; Yanch, J.C. (Massachusetts Institute of Technology, Nuclear Reactor Laboratory, Cambridge, Massachusetts 02139 (United States))

1994-10-01

288

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

PubMed

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 and thermalize, and a photon field is generated from neutron capture in hydrogen. In this paper, a method to determine the doses from thermal and fast neutrons, photons, and the B-10(n, alpha)Li-7 reaction is presented. The photon and fast neutron doses are measured with ionization chambers, in realistic phantoms, using the dual chamber technique. The thermal neutron flux is measured with gold foils using the cadmium difference technique, the thermal neutron and B-10 doses are determined by the kerma factor method. Representative results are presented for a unilateral irradiation of the head. Sources of error in the method as applied to BNCT dosimetry, and the uncertainties in the calculated doses are discussed. PMID:7869994

Rogus, R D; Harling, O K; Yanch, J C

1994-10-01

289

Boron neutron capture therapy of intracerebral rat gliosarcomas.  

PubMed Central

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

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

1990-01-01

290

Neutron Capture Gamma-Ray Studies of Silicon, Titanium and Erbium Isotopes.  

National Technical Information Service (NTIS)

The paper gives reviews of research on neutron capture gamma ray spectroscopy using a Ge(Li) detector in combination with a single flat crystal diffraction spectrometer. The research includes gamma ray spectroscopy of erbium, calcium, titanium, and silico...

K. C. Tripathi

1969-01-01

291

Boron neutron capture therapy of ocular melanoma and intracranial glioma using p-boronophenylalanine.  

National Technical Information Service (NTIS)

During conventional radiotherapy, the dose that can be delivered to the tumor is limited by the tolerance of the surrounding normal tissue within the treatment volume. Boron Neutron Capture Therapy (BNCT) represents a promising modality for selective tumo...

J. A. Coderre D. Greenberg P. L. Micca D. D. Joel S. Saraf

1990-01-01

292

Parity-violating gamma-ray asymmetry in the neutron-proton capture  

Microsoft Academic Search

An experiment to measure ?-ray asymmetry A? with a high precision in neutron-proton radiative capture is under construction at LANSCE. The experiment will determine the weak pion-nucleon coupling constant H?1,, 30% of its predicted value.

Y. Masuda; J. D. Bowman; R. D. Carlini; T. Case; T. E. Chupp; K. P. Coulter; S. J. Freedman; T. R. Gentile; M. Gericke; G. L. Greene; F. W. Hersmann; T. Ino; S. Ishimoto; G. L. Jones; M. B. Leuschner; G. S. Mitchell; K. Morimoto; S. Muto; H. Nann; S. A. Page; S. I. Pentilla; W. D. Ramsay; E. I. Sharapov; T. B. Smith; W. M. Snow; S. W. Wilburn; Y. W. Yuan

2003-01-01

293

Proposed Protocol for Clinical Trials of Boron Neutron Capture Therapy in Glioblastoma Multiforme.  

National Technical Information Service (NTIS)

Neutron Capture Therapy (NCT) was suggested in theory as a treatment for malignant tumors some 50 years ago. Since then, considerable data have accumulated on the mechanisms of action and possible application of this technique. This paper outlines a proto...

R. V. Dorn J. H. Spickard M. L. Griebenow

1988-01-01

294

Neutron Capture Experiments on Unstable Nuclei. Annual Technical Report for Period November 2002-November 2003.  

National Technical Information Service (NTIS)

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 interpretati...

J. M. Schwantes R. Sudowe H. Nitsche D. C. Hoffman

2003-01-01

295

Proposed Protocol for Clinical Trials of Boron Neutron Capture Therapy in Glioblastoma Multiforme.  

National Technical Information Service (NTIS)

Neutron capture therapy (NCT) was suggested in theory as a treatment for malignant tumors some 50 years ago. Since then considerable data have accumulated on the mechanisms of action and possible application of this technique. A comprehensive national bor...

R. V. Dorn J. H. Spickard M. L. Griebenow

1988-01-01

296

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

297

(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

298

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

299

Radiative strength functions of germanium from thermal neutron capture  

SciTech Connect

Thermal neutron capture gamma rays from germanium have been studied using an internal irradiation facility and a pair spectrometer. Energy and intensity of transitions in four germanium isotopes were determined and their level and separation energies inferred. The separation energies are {ital S}{sub {ital n}} ({sup 71}Ge)=7415.95{plus minus}0.05 keV, {ital S}{sub {ital n}} ({sup 73}Ge)=6782.94{plus minus}0.05 keV, {ital S}{sub {ital n}} ({sup 74}Ge)=10 196.31{plus minus}0.07 keV, and {ital S}{sub {ital n}} ({sup 75}Ge)=6505.26{plus minus}0.08 keV. The {ital E}1 reduced strength function, {l angle}{Gamma}{sub {gamma}{ital i}D}{sup {minus}1}{ital E}{sub {ital i}}{sup {minus}3}{ital A{minus}2/3}{r angle}, of these germanium isotopes was found to be (1.8{plus minus}0.5){times}10{sup {minus}9} MeV{sup {minus}3}, a value lower than the global average. The {ital M}1 strength function {l angle}{Gamma}{sub {gamma}{ital i}D}{sup {minus}1}{ital E}{sub {ital i}}{sup {minus}3}{r angle} of {sup 74}Ge was estimated to be (20{plus minus}9){times}10{sup {minus}9} MeV{sup {minus}3} which agrees with the global average. The average {ital B}({ital E}2){bar {down arrow}} of {sup 74}Ge using the present thermal data and the previous resonance data from literature was found to be 18{plus minus}10{ital e}{sup 2} fm{sup 4} MeV {sup {minus}1} which agrees with the value predicted by the Axel-Brink hypothesis.

Islam, M.A.; Kennett, T.J.; Prestwich, W.V. (Department of Physics, McMaster University, Hamilton, Ontario, Canada L8S 4K1 (CA))

1991-03-01

300

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

SciTech Connect

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

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

1999-06-06

301

Reexamination of 2200 meter/second cross section experiments for neutron capture and fission standards  

SciTech Connect

Neutron capture and fission reaction cross sections are usually measured relative to a standard basis. The most common absolute cross sections which are used in the thermal neutron energy region are /sup 197/Au and /sup 59/Co for capture reactions and /sup 235/U and /sup 239/Pu for fission reactions. Values for these four cross sections have been compiled and evaluated for the purpose of recommending standard values. 24 refs., 5 tabs. (WRF)

Holden, N.E.; Holden, K.A.

1985-01-01

302

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

303

A setup for precise measurement of resonance neutron capture by self-indication  

Microsoft Academic Search

In order to measure neutron capture self-indication in the neutron energy range up to 200 keV, a setup based on a 16-section NaI(Tl) scintillation gamma detector has been created at the 500-m flight path of the IBR-30 booster (JINR-Dubna). The detector has a geometric efficiency of 80% and a total scintillator volume of 36 1. The capture self-indication ratio Tgamma(n)

N. Janeva; S. Toshkov; G. V. Muradyan; Yu. V. Grigorjev; G. Georgiev; I. Sirakov; V. G. Tishin; Yu. S. Zamjatnin

1992-01-01

304

Capture ?-rays from 60Co as multi ?-ray efficiency standard for prompt ?-ray neutron activation analysis  

Microsoft Academic Search

The absolute emission probabilities of 49 ?-rays from thermal neutron capture in 59Co were measured in the energy range of 150–7500 keV. Two independent approaches were used to arrive at the number of captured neutrons. It has been proposed to use cobalt as a standard for absolute efficiency calibration of the detector over a wide energy range and as a

K Sudarshan; A. G. C Nair; R. N Acharya; Y. M Scindia; A. V. R Reddy; S. B Manohar; A Goswami

2001-01-01

305

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

PubMed

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

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

2000-07-01

306

An improved neutron collimator for brain tumor irradiations in clinical boron neutron capture therapy  

SciTech Connect

To improve beam penetration into a head allowing the treatment of deeper seated tumors, two neutron collimators were built sequentially and tested for use in the clinical boron neutron capture therapy (BNCT) program at the epithermal neutron irradiation facility of the Brookhaven Medical Research Reactor. The collimators were constructed from lithium-impregnated polyethylene, which comprises Li{sub 2}CO{sub 3} powder ({approx_equal}93{percent} enriched isotopic {sup 6}Li) uniformly dispersed in polyethylene to a total {sup 6}Li content of 7.0 wt.{percent}. The first collimator is 7.6 cm thick with a conical cavity 16 cm in diameter on the reactor core side tapering to 8 cm facing the patient{close_quote}s head. The second collimator is 15.2 cm thick with a conical cavity 20 cm in diameter tapering to 12 cm. A clinical trial of BNCT for patients with malignant brain tumors is underway using the first collimator. Results of phantom dosimetry and Monte Carlo computations indicate that the new 15.2 cm thick collimator will improve the neutron beam penetration. Thus, the second collimator was made and will be used in an upcoming clinical trial. In-air and in-phantom mixed-field dosimetric measurements were compared to Monte Carlo computations for both collimators. The deeper penetration is achieved but at a sacrifice in beam intensity. In this report, a performance comparison of both collimators regarding various fluence rate and absorbed dose distributions in a head model is presented and discussed. {copyright} {ital 1996 American Association of Physicists in Medicine.}

Liu, H.B.; Greenberg, D.D.; Capala, J. [Medical Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Wheeler, F.J. [Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415 (United States)

1996-12-01

307

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

308

Molecular Targeting of the Epidermal Growth Factor Receptor for Neutron Capture Therapy of Gliomas1  

Microsoft Academic Search

Success of boron neutron capture therapy (BNCT) is dependent on cellular and molecular targeting of sufficient amounts of boron-10 to sustain a lethal 10B (n, ) 7Li capture reaction. The purpose of the present study was to determine the efficacy of boronated epidermal growth factor (EGF) either alone or in combination with boronophe- nylalanine (BPA) as delivery agents for an

F. Barth; Weilian Yang; Dianne M. Adams; Joan H. Rotaru; Supriya Shukla; Masaru Sekido; Werner Tjarks; Robert A. Fenstermaker; Michael Ciesielski; Marta M. Nawrocky; Jeffrey A. Coderre

2002-01-01

309

Photoneutron and Photofission Cross Sections for URANIUM238 and THORIUM232 Using Neutron Capture Gamma Rays  

Microsoft Academic Search

The photofission and total photoneutron cross sections of ('238)U and ('232)Th have been measured as a function of energy between 4 and 11 Mev. The photons used were those produced in the neutron capture reaction in the Tangential Beam Port Facility of the University of Virginia Reactor. The capture gamma ray sources used were the following; Al, Cr, Co, Cu,

Walter John Varhue

1984-01-01

310

Measurement of keV-Neutron Capture Gamma Rays for Se Isotopes  

SciTech Connect

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

Igashira, Masayuki; Kamada, So; Katabuchi, Tatsuya; Mizumoto, Motoharu [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1O-Okayama, Meguro-ku, Tokyo 152-8550 (Japan)

2009-01-28

311

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

312

NEUTRON ENERGY SPECTRA FROM NUCLEI EXCITED BY $mu$⁻MESON CAPTURE (thesis)  

Microsoft Academic Search

The neutron energy spectra from nuclear capture of mu mesons in Al, Ca, ; Fe, Ag, I, Au, and Pb were measured. Nuclear temperatures were deduced from the ; spectra according to the Weisskopf evaporation theory. Results were compared to ; other experimental measurements and consistency with compound nuclear theory was ; discussed. The direct neutron emission spectrum was calculated

Hagge

1963-01-01

313

Neutron capture gamma-ray technique for in situ mineral analysis.  

National Technical Information Service (NTIS)

The application of neutron capture gamma ray method for in situ analysis of mineral deposits is discussed. A borehole sonde for prompt gamma analysis (PGA) using a 3 Ci Americium-Beryllium neutron source and a hyper pure germanium detector has been design...

A. A. Elkady W. H. Abulfaraj A. F. Abdulfattah

1987-01-01

314

Determination of boron in food and biological reference materials by neutron capture prompt-? activation  

Microsoft Academic Search

Boron concentrations were determined by in-beam neutron capture prompt-? activation analysis for 31 food and biological reference materials prepared by the National Institute of Standards and Technology, Agriculture Canada, the National Institute for Environmental Studies of Japan, and the International Atomic Energy Agency. Sensitivity and background enhancements that are consequences of neutron scattering in hydrogenous matrices such as biological reference

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

1990-01-01

315

Radiative Strength Function Using the Neutron-Capture Reaction on 151, 153Eu.  

National Technical Information Service (NTIS)

Radiative strength functions in (sup 152,154)Eu nuclei for (gamma)-ray energies below 6 MeV have been investigated. Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for (sup 151,153)Eu targets. Properties of resonances in...

U. Agvaanluvsan A. Alpizar-Vicent J. A. Becker F. Becvar T. A. Bredeweg R. Clement E. Esch C. M. Foldne R. Hatarik R. C. Haight D. C. Hoffman M. Krticka

2005-01-01

316

The design, construction and performance of a variable collimator for epithermal neutron capture therapy beams  

Microsoft Academic Search

A patient collimator for the fission converter based epithermal neutron beam (FCB) at the Massachusetts Institute of Technology Research Reactor (MITR-II) was built for clinical trials of boron neutron capture therapy (BNCT). A design was optimized by Monte Carlo simulations of the entire beam line and incorporates a modular construction for easy modifications in the future. The device was formed

K J Riley; P J Binns; S J Ali; O K Harling

2004-01-01

317

Heat generation and temperature-rise in ordinary concrete due to capture of thermal neutrons.  

National Technical Information Service (NTIS)

The aim of this work is the evaluation of the heat generation and temperature-rise in local ordinary concrete as a biological shield due to capture of total thermal and reactor thermal neutrons. The total thermal neutron fluxes were measured and calculate...

E. A. Abdo E. Amin

1997-01-01

318

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

SciTech Connect

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

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

1997-12-31

319

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

Microsoft Academic Search

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

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

2008-01-01

320

Power Burst Facility\\/Boron Neutron Capture Therapy Program for Cancer Treatment: Volume 4, No. 5  

Microsoft Academic Search

Highlights of the Power Burst Facility Boron Neutron Capture Therapy (PBF\\/BNCT) Program during April 1990 include progress within areas of: gross boron analysis in tissue, blood, and urine; analytical methodologies development for BSH (Borocaptate Sodium) purity determination; noninvasive boron quantitative determination; analytical radiation transport and interaction modeling for BNCT; large animal model studies; neutron source and facility preparation; administration and

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

1990-01-01

321

Power Burst Facility\\/Boron Neutron Capture Therapy Program for Cancer Treatment: Volume 4, No. 4  

Microsoft Academic Search

Highlights of the Power Burst Facility Boron Neutron Capture Therapy (PBF\\/BNCT) Program during April 1990 include progress within the areas of: gross boron analysis in tissue, blood, and urine; analytical methodologies development for BSH (Borocaptate Sodium) purity determination; noninvasive boron quantitative determination; operator training was conducted and pharmacokinetic data obtained using a laboratory dog; dosimetry development continues on real-time neutron

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

1990-01-01

322

Precision Measurement of Parity Violation in Polarized Cold Neutron Capture on the Proton: the NPDGamma Experiment  

SciTech Connect

The NPD{gamma} experiment at the Los Alamos Neutron Science Center (LANSCE) is dedicated to measure with high precision the parity violating asymmetry in the {gamma} emission after capture of spin polarized cold neutrons in para-hydrogen. The measurement will determine unambiguously the weak pion-nucleon-nucleon ({pi} NN) coupling constant (line integral){sub {pi}}{sup l}.

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

2005-10-24

323

Three-Center Coulombic Over-Barrier Model for Multiple Electron Capture by Slow Highly Charged Ions from Diatomic Molecules  

Microsoft Academic Search

A three-center Coulombic over-barrier model is proposed for the process of multiple electron capture from homonuclear diatomic molecules in collisions with slow highly charged ions. The present model, based on the over-barrier model for atomic targets given by Niehaus, takes further into account the two-center nature of molecular targets by introducing a three-center Coulomb potential for respective electrons. Cross sections

A. Ichimura; T. Ohyama-Yamaguchi

1999-01-01

324

Multiple electron capture and photon emission of slow highly charged Taq+ ions in collisions with He and Xe  

Microsoft Academic Search

Multiple electron capture and photon emission in slow (velocity v ~ 0.3 au) collisions by highly charged Taq+(q = 41-49) projectile ions and atomic targets of He and Xe were investigated. The absolute photon yield, or number of x-rays emitted from the projectile ion, showed considerably different behaviours in two distinctive regions of projectile charge state q: the closed M-shell

S. Madzunkov; D. Fry; R. Schuch

2004-01-01

325

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

NASA Astrophysics Data System (ADS)

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

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

2004-01-01

326

Analytical neutron-capture gamma-ray spectroscopy: Status and prospects  

Microsoft Academic Search

The use of neutron-capture gamma rays for elemental analysis has become an established technique, applicable for the measurement of a list of elements which complements conventional delayed-gamma neutron activation analysis. Three distinct areas of application of the prompt method have been laboratory-based analysis using reactor neutrons, field measurements (especially borehole logging for mineral exploration), and industrial process stream analysis, the

Richard M. Lindstrom; David L. Anderson

1985-01-01

327

Determination of metals in alloys by neutron capture gamma-ray spectrometry  

Microsoft Academic Search

A collimated neutron beam capable of providing a thermal neutron flux of 4.75·107 n·cm?2·sec?1 has been used to analyze alloy samples of 1–5 g during relatively short irradiation times of 30 min by the use of neutron\\u000a capture gamma-ray spectrometry. The analyses were performed by using a mathematical treatment that relates the count ratio\\u000a of every constituent present in the

M. Heurtebise; J. A. Lubkowitz

1976-01-01

328

A 4? BaF2 detector for measuring neutron capture on unstable nuclei.  

NASA Astrophysics Data System (ADS)

Measurements of neutron capture on unstable nuclei are important for studies of s-process nucleosynthesis, nuclear waste transmutation, and stewardship science. A 160-element, 4? BaF2 detector array and neutron flight path has been designed to make capture measurements at the moderated spallation neutron source at LANSCE. Measurements can be made on as little as 1 mg of sample material over energies from thermal to near 100 keV. We will describe the design and construction status of the DANCE array and present flux measurements from the flight path commissioning experiment.

Ullmann, J. L.; Haight, R. C.; Hunt, L.; Seabury, E. H.; Rundberg, R. S.; Dragowsky, M. R.; Fowler, M. M.; Miller, G. G.; Wilhelmy, J. B.; Strottman, D. D.; Chamberlin, E. P.; Heil, M.; Reifarth, R.; Kaeppeler, F.

2002-04-01

329

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

330

The photon-isoeffective dose in boron neutron capture therapy.  

PubMed

With the aim to relate the effects observed in a clinical boron neutron capture therapy protocol to the corresponding outcomes in a standard photon radiation therapy, "RBE-weighted" doses are customarily calculated by adding the contributions of the different radiations, each one weighted by a fixed (dose and dose rate independent) relative biological effectiveness factor. In this study, the use of fixed factors is shown to have a formal inconsistency, which in practice leads to unrealistically high tumor doses. We then introduce a more realistic approach that essentially exploits all the experimental information available from survival experiments. The proposed formalism also includes first-order repair of sublethal lesions by means of the generalized Lea-Catcheside factor in the modified linear-quadratic model, and considers synergistic interactions between different radiations. This formalism is of sufficient simplicity therefore to be directly included in all BNCT treatment planning systems. In light of this formalism, the photon-isoeffective doses for two BNCT clinical targets were computed and compared with the standard dose calculation procedure. For the case of brain tumors and clinically relevant absorbed doses, the proposed approach derives isoeffective doses that are much lower than the fixed RBE method, regardless of considering synergism. Thus, for a tumor that receives a mean total absorbed dose of 15 Gy (value achievable with 50 ppm of boron concentration and typical beams used in the clinic), the photon-isoeffective doses are 28 Gy (IsoE) and 30 Gy (IsoE) (without and with synergism, respectively), in contrast to 51 Gy (RBE) for the fixed RBE method. When the clinical outcome of the Argentine cutaneous melanoma treatments is assessed with regard to the doses derived from the standard procedure, it follows that the fixed RBE approach is not suitable to understand the observed clinical results in terms of the photon radiotherapy data. Moreover, even though the assumed (10)B concentration in tumors is lowered to reduce the obtained doses with the standard procedure, the fixed RBE approach is still unsuitable to explain the observed outcomes (the model is always rejected with P values of virtually zero). Additionally, the numbers of controlled tumors predicted by the proposed approach are statistically consistent with observed outcomes. As a by-product of this work, a dose-response clinical reference for single-fraction melanoma treatments is developed. PMID:23148506

González, Sara J; Santa Cruz, Gustavo A

2012-11-13

331

THE UBIQUITY OF THE RAPID NEUTRON-CAPTURE PROCESS  

SciTech Connect

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.

Roederer, Ian U.; Sneden, Christopher [Department of Astronomy, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712-0259 (United States); Cowan, John J. [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Karakas, Amanda I. [Research School of Astronomy and Astrophysics, Australian National University, Mount Stromlo Observatory, Cotter Road, Weston, ACT 2611 (Australia); Kratz, Karl-Ludwig [Max-Planck-Institut fuer Chemie, Otto-Hahn-Institut, J.-J.-Becherweg 27, D-55128 Mainz (Germany); Lugaro, Maria [Centre for Stellar and Planetary Astrophysics, School of Mathematical Sciences, Monash University, Clayton, VIC 3800 (Australia); Simmerer, Jennifer [Department of Physics and Astronomy, University of Utah, 115 S. 1400 E., Salt Lake City, UT 84112-0830 (United States); Farouqi, Khalil, E-mail: iur@obs.carnegiescience.ed [Zentrum fuer Astronomie der Universitaet Heidelberg, Landessternwarte, Koenigstuhl 12, D-69117 Heidelberg (Germany)

2010-12-01

332

Induction of DNA double-strand breaks by sup 157 Gd neutron capture  

SciTech Connect

The rationale of boron (10B) neutron capture therapy (BNCT) is based on the high thermal neutron capture cross section of 10B and the limited maximum range (about one cell diameter) of the high LET fission products of the boron neutron capture (NC) reaction. The resulting radiochemical damage is confined to the cell containing the BNC reaction. Although other nuclides have higher thermal neutron capture cross sections than 10B, NC by such nuclides results in the emission of highly penetrating gamma rays. However, gadolinium-157 ({sup 157}Gd) n-gamma reaction is also accompanied by some internal conversion and, by implication, Auger electron emission. Irradiation of Gd3+-DNA complexes with thermal neutrons results in the induction of DNA double-strand (ds) breaks, but the effect is largely abrogated in the presence of EDTA. Thus, by analogy with the effects of decay of Auger electron-emitting isotopes such as {sup 125}I, the Gd NC event must take place in the close proximity of DNA in order to induce a DNA ds break. It is proposed that {sup 157}Gd-DNA ligands therefore have potential in NCT. The thermal neutron capture cross section of {sup 157}Gd, a nonradioactive isotope, is more than 50 times that of 10B. 14 references.

Martin, R.F.; D'Cunha, G.; Pardee, M.; Allen, B.J. (Peter MacCallum Cancer Institute, Melbourne, New South Wales (Australia))

1989-07-01

333

Promising cancer treatment modality: the University of California Davis\\/McClellan Nuclear Radiation Center neutron capture therapy program  

Microsoft Academic Search

Neutron capture therapy (NCT) is a promising new binary therapeutic modality for the treatment of localized tumors. It is accomplished by injection and localization within the tumor of a neutron capture agent (NCA) that alone, is non- toxic. Whenthe tumor is then exposed to neutrons, a relatively non-toxic form of radiation, crytotoxic products are produced that directly or indirectly cause

Susan A. Autry-Conwell; James E. Boggan; Benjamin F. Edwards; Yongjin Hou; Maria-Graca Vincente; Hungyuan Liu; Wade J. Richards

2000-01-01

334

The ?-ray spectrum of fission products from slow neutron irradiation of uranium 235  

Microsoft Academic Search

The fission products from uranium 235, irradiated by slow neutrons, have been analysed by a two-crystal ?-ray scintillation spectrometer. The spectrum between one day and seventy days after irradiation has been recorded. The gross spectrum varies with time and consists of two groups of lines around 0.2 and 0.7 MeV, with a single line at 1.58 MeV as the only

D H Peirson

1955-01-01

335

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

336

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

337

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

SciTech Connect

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

Ohgama, Kazuya; Igashira, Masayuki; Ohsaki, Toshiro [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-26 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan)

2006-03-13

338

A state-of-the-art epithermal neutron irradiation facility for neutron capture therapy.  

PubMed

At the Massachusetts Institute of Technology (MIT) the first fission converter-based epithermal neutron beam (FCB) has proven suitable for use in clinical trials of boron neutron capture therapy (BNCT). The modern facility provides a high intensity beam together with low levels of contamination that is ideally suited for use with future, more selective boron delivery agents. Prescriptions for normal tissue tolerance doses consist of 2 or 3 fields lasting less than 10 min each with the currently available beam intensity, that are administered with an automated beam monitoring and control system to help ensure safety of the patient and staff alike. A quality assurance program ensures proper functioning of all instrumentation and safety interlocks as well as constancy of beam output relative to routine calibrations. Beam line shutters and the medical room walls provide sufficient shielding to enable access and use of the facility without affecting other experiments or normal operation of the multipurpose research reactor at MIT. Medical expertise and a large population in the greater Boston area are situated conveniently close to the university, which operates the research reactor 24 h a day for approximately 300 days per year. The operational characteristics of the facility closely match those established for conventional radiotherapy, which together with a near optimum beam performance ensure that the FCB is capable of determining whether the radiobiological promise of NCT can be realized in routine practice. PMID:15446801

Riley, K J; Binns, P J; Harling, O K

2004-08-21

339

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

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

340

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

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

341

Data evaluation methods and improvements to the neutron-capture ?-ray spectrum  

NASA Astrophysics Data System (ADS)

Improved neutron-capture ?-ray spectra, not only of interest to the nuclear structure and reactions communities, are needed in a variety of applied and non-proliferation programs. This requires an evaluation of the existing experimental capture-? data. Elemental neutron-capture data taken from direct measurements at the Budapest Reactor have been used to collate the Evaluated Gamma-ray Activation File, a database of capture ?-ray cross sections. These cross sections are then compared to Monte Carlo simulations of ?-ray emission following the thermal neutron-capture process using the statistical-decay code DICEBOX. The aim of this procedure is to obtain the total radiative neutron-capture cross section and confidently increase the number of levels and ? rays that can be assigned to a given isotope in the neutron data libraries. To achieve these goals and provide as complete information as possible in the neutron data libraries, it is also necessary to remain current with recent advances in nuclear structure physics and ensure that the latest data in the Evaluated Nuclear Structure Data File has been taken into consideration. This way an optimal level scheme can be derived by comparison with simulations and available experimental data. New information derived from this study can then be used to improve the nuclear structure and reactions databases with more-complete level schemes, and indeed, provide reliable and accurate input to a variety of applications which require this information. Recent results from neutron capture on the stable tungsten isotopes 182,183,184,186W are presented to illustrate the evaluation process.

Hurst, A. M.; Firestone, R. B.; Summers, N. C.; Sleaford, B. W.; Revay, Zs.; Krti?ka, M.; Belgya, T.; Basunia, M. S.; Capote, R.; Choi, H.; Dashdorj, D.; Escher, J. E.; Nichols, A.; Szentmiklósi, L.

2011-06-01

342

Optical Spectroscopy of Slow, Highly Charged Ions after Collision with - Study of Electron Capture  

Microsoft Academic Search

We have studied electron capture using a recoil ion source to produce beams of neon and argon ions, directed into a beam of atomic sodium. We have measured the wavelengths, relative intensities, and polarizations of the subsequent visible radiation due to DeltaN = -1 transitions. We have determined the partial capture cross sections of these systems as a function of

David Michael Gauntt

1990-01-01

343

Multiple electron capture and photon emission of slow highly charged Taq+ ions in collisions with He and Xe  

NASA Astrophysics Data System (ADS)

Multiple electron capture and photon emission in slow (velocity v ~ 0.3 au) collisions by highly charged Taq+(q = 41-49) projectile ions and atomic targets of He and Xe were investigated. The absolute photon yield, or number of x-rays emitted from the projectile ion, showed considerably different behaviours in two distinctive regions of projectile charge state q: the closed M-shell region (q < 45) and the open M-shell region (q > 45). We find that for a closed Ta M shell, in the case of He but not Xe, the absolute photon yield is smaller when two electrons are captured than in the case of single electron capture. For an open Ta M shell it is the opposite for both atomic targets. The branching ratios between three processes, radiative stabilization, internal dielectronic excitation (IDE) and Auger transition, are understood to have a critical influence on these different behaviours. Furthermore, it is found that these branching ratios are strongly influenced by the states into which electrons are captured, thus by the target atom species, and by the projectile core configuration. From our measurement of absolute photon yields for different capture channels, we derived the Auger probabilities after capture from He and Xe to be 0.5(2) and 0.7(2), respectively. We investigated multiple capture in the case of Xe when more than six electrons are transferred in the collision. A simple relation for the increase of the photon yield with increasing number of captured electrons is given.

Madzunkov, S.; Fry, D.; Schuch, R.

2004-08-01

344

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

345

The Abundances of Light Neutron-Capture Elements in Planetary Nebulae  

NASA Astrophysics Data System (ADS)

I present results of the first large-scale survey of neutron(n)-capture elements (Z > 30) in planetary nebulae (PNe). I have observed the near-infrared emission lines [Kr III] 2.199 and [Se IV] 2.287 microns in over 100 PNe, using the CoolSpec spectrometer on the 2.7-m Harlan J. Smith Telescope at McDonald Observatory. Se (Z = 34) and Kr (Z = 36) may be enriched in PNe if their progenitor stars experienced slow n-capture nucleosynthesis (the ``s-process'') and convective dredge-up during the AGB. This survey provides the first insight into s-process nucleosynthesis in PN progenitor stars as a population. Se and/or Kr have been detected in 65 of 114 PNe, for a detection rate of nearly 60%. I have added Se and Kr to the atomic databases of the publicly available photoionization codes CLOUDY and XSTAR, which I use to correct for unseen ionization stages and thereby derive elemental abundances. Our analysis shows that Se and Kr abundances are enhanced relative to solar in about 40% of the PNe exhibiting [Se IV] and [Kr III] emission. This provides evidence that the s-process occurred in the progenitor stars, with varying efficiencies as implied by the range of enhancements (1--5 times solar). Kr tends to be more enriched than Se, in agreement with theoretical models of s-process nucleosynthesis. I find that Se and Kr tend to be more strongly enhanced in PNe with hydrogen-deficient central stars exhibiting Wolf-Rayet emission features, as well as objects with lower mass (M < 4 Msun) progenitors. These results provide important information for models of s-process nucleosynthesis, and our understanding of the evolution of low- and intermediate-mass stars and their impact on the chemical enrichment of the Galaxy.

Sterling, N. C.

2005-12-01

346

Boron Neutron-Capture Therapy (BNCT) for Glioblastoma Multiforme (GBM) Using the Epithermal Neutron Beam at the Brookhaven National Laboratory  

Microsoft Academic Search

Objective: Boron neutron-capture therapy (BNCT) is a binary form of radiation therapy based on the nuclear reactions that occur when boron (10B) is exposed to thermal neutrons. Preclinical studies have demonstrated the therapeutic efficacy of p-boronophenylalanine (BPA)-based BNCT. The objectives of the Phase I\\/II trial were to study the feasibility and safety of single-fraction BNCT in patients with GBM.Materials and

Manjeet Chadha; Jacek Capala; Jeffrey A Coderre; Eric H Elowitz; Jun-ichi Iwai; Darrel D Joel; Hungyuan B Liu; Lucian Wielopolski; Arjun D Chanana

1998-01-01

347

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

348

Proposal of a wide-band mirror polarizer of slow neutrons at a pulsed neutron source  

Microsoft Academic Search

The new type of wide-band mirror-based neutron polarizer, which is to be operated at a pulsed neutron source, is suggested. The idea is to use a movable polarizing mirror system, which, with the incoming beam monochromatized by the time-of-flight, would allow one to tune glancing angles in time so that the total reflection condition is always fulfilled only for one

Yu. V. Nikitenko; Yu. M. Ostanevich

1993-01-01

349

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

350

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

351

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

SciTech Connect

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

Evans, Louise G [Los Alamos National Laboratory; Schear, Melissa A [Los Alamos National Laboratory; Hendricks, John S [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory; Croft, Stephen [Los Alamos National Laboratory

2010-12-14

352

A new NCNPX PTRAC coincidence capture file capability: a tool for neutron detector design  

SciTech Connect

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

Evans, Louise G [Los Alamos National Laboratory; Schear, Melissa A [Los Alamos National Laboratory; Hendricks`, John S [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Tobin, Stephen J [Los Alamos National Laboratory; Croft, Stephen [Los Alamos National Laboratory

2011-01-13

353

Neutron diffraction measurements at the INES diffractometer using a neutron radiative capture based counting technique  

Microsoft Academic Search

The global shortage of 3He gas is an issue to be addressed in neutron detection. In the context of the research and development activity related to the replacement of 3He for neutron counting systems, neutron diffraction measurements performed on the INES beam line at the ISIS pulsed spallation neutron source are presented. For these measurements two different neutron counting devices

G. Festa; A. Pietropaolo; F. Grazzi; E. Barzagli; A. Scherillo; E. M. Schooneveld

2011-01-01

354

Neutron detection by measuring capture gammas in a calorimetric approach  

Microsoft Academic Search

Radiation detector systems for homeland security applications have been usually equipped with 3He tubes to detect the distinguished neutron signature of Special Nuclear Materials (SNMs). The serious shortage of 3He gas, however, recently initiated substantial efforts to develop alternative neutron detectors, particularly for large-area Radiation Portal Monitors (RPMs). Most activities are currently directed to detectors comprising 6Li or 10B —

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

2010-01-01

355

License amendment for neutron capture therapy at the MIT research reactor  

SciTech Connect

This paper reports the issuance by the U.S. Nuclear Regulatory Commission (NRC) of a license amendment to the Massachusetts Institute of Technology (MIT) for the use of the MIT Research Reactor's (MITR-II) medical therapy facility beam for the treatment of humans using neutron capture therapy (NCT). This amendment is one of 11 required approvals. The others are those of internal MIT committees, review panels of the Tufts-New England Medical Center (NEMC), which is directing the program jointly with MIT, that of the U.S. Food and Drug Administration, and an NRC amendment to the NEMC hospital license. This amendment is the first of its type to be issued by NRC, and as such it establishes a precedent for the conduct of human therapy using neutron beams. Neutron capture therapy is a bimodal method for treating cancer that entails the administration of a tumor-seeking boronated drug followed by the irradiation of the target organ with neutrons. The latter cause boron nuclei to fission and thereby release densely ionizing helium and lithium nuclei, which destroy cancerous cells while leaving adjacent healthy cells undamaged. Neutron capture therapy is applicable to glioblastoma multiforme (brain tumors) and metastasized melanoma (skin cancer). Both Brookhaven National Laboratory and MIT conducted trials of NCT more than 30 yr ago. These were unsuccessful because the available boron drugs did not concentrate sufficiently in tumor and because the thermal neutron beams that were used did not enable neutrons to travel deep enough into the brain.

Bernard, J.A. (Massachusetts Institute of Technology, Cambride, MA (United States))

1993-01-01

356

Monte Carlo based dosimetry and treatment planning for neutron capture therapy of brain tumors  

SciTech Connect

Monte Carlo based dosimetry and computer-aided treatment planning for neutron capture therapy have been developed to provide the necessary link between physical dosimetric measurements performed on the MITR-II epithermal-neutron beams and the need of the radiation oncologist to synthesize large amounts of dosimetric data into a clinically meaningful treatment plan for each individual patient. Monte Carlo simulation has been employed to characterize the spatial dose distributions within a skull/brain model irradiated by an epithermal-neutron beam designed for neutron capture therapy applications. The geometry and elemental composition employed for the mathematical skull/brain model and the neutron and photon fluence-to-dose conversion formalism are presented. A treatment planning program, NCTPLAN, developed specifically for neutron capture therapy, is described. Examples are presented illustrating both one and two-dimensional dose distributions obtainable within the brain with an experimental epithermal-neutron beam, together with beam quality and treatment plan efficacy criteria which have been formulated for neutron capture therapy. The incorporation of three-dimensional computed tomographic image data into the treatment planning procedure is illustrated. The experimental epithermal-neutron beam has a maximum usable circular diameter of 20 cm, and with 30 ppm of B-10 in tumor and 3 ppm of B-10 in blood, it produces a beam-axis advantage depth of 7.4 cm, a beam-axis advantage ratio of 1.83, a global advantage ratio of 1.70, and an advantage depth RBE-dose rate to tumor of 20.6 RBE-cGy/min (cJ/kg-min). These characteristics make this beam well suited for clinical applications, enabling an RBE-dose of 2,000 RBE-cGy/min (cJ/kg-min) to be delivered to tumor at brain midline in six fractions with a treatment time of approximately 16 minutes per fraction.

Zamenhof, R.G.; Clement, S.D.; Harling, O.K.; Brenner, J.F.; Wazer, D.E.; Madoc-Jones, H.; Yanch, J.C. (Tufts-New England Medical Center, Boston, MA (USA))

1990-01-01

357

Simulated Borehole for Ore Depth Evaluation by Neutron Capture gamma-Ray Technique Using Pu/Be Neutron Source.  

National Technical Information Service (NTIS)

In this work an attempt was made to study the response as well as the effective depth of a borehole sonde designed and tested for possible in situ ore analysis. A laboratory model to function as a borehole probe for elemental analysis by neutron capture g...

A. Z. Hussein A. M. Hassan H. G. Ahmed A. A. El-Kady

1982-01-01

358

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

359

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

NASA Astrophysics Data System (ADS)

A recent X-ray spectroscopy experiment on 255 keV Ar^17+-Ar collisions [1] provided evidence for strong multiple-electron capture --- a feature that is supported by classical trajectory Monte Carlo calculations for similar collision systems [2]. We have coupled a quantum-mechanical independent-electron model calculation for the Ar^17+-Ar system with (semi-) phenomenological Auger and radiative cascade models to test these findings. The capture calculations are performed using the basis generator method and include single-particle states on the projectile up to the 10th shell. The cross sections obtained for shell-specific multiple capture are fed into a stabilization scheme proposed in Ref. [3] in order to obtain n-specific cross sections for apparent single (and double) capture that in turn are fed into a radiative cascade code [1] to obtain X-ray emission intensities that can be compared with the experimental data. Good agreement is found for the Lyman series from n=3 to n=7 if the multiple-capture contributions are included, whereas calculations that ignore them are in stark conflict with the data. [4pt] [1] M. Trassinelli et al., J. Phys. B 45, 085202 (2012)[0pt] [2] S. Otranto and R. Olson, Phys. Rev. A 83, 032710 (2011)[0pt] [3] R. Ali et al., Phys. Rev A 49, 3586 (1994).

Salehzadeh, Arash; Kirchner, Tom

2012-10-01

360

Experimental verification of improved depth-dose distribution using hyper-thermal neutron incidence in neutron capture therapy.  

PubMed

We have proposed the utilization of 'hyper-thermal neutrons' for neutron capture therapy (NCT) from the viewpoint of the improvement in the dose distribution in a human body. In order to verify the improved depth-dose distribution due to hyper-thermal neutron incidence, two experiments were carried out using a test-type hyper-thermal neutron generator at a thermal neutron irradiation field in Kyoto University Reactor (KUR), which is actually utilized for NCT clinical irradiation. From the free-in-air experiment for the spectrum-shift characteristics, it was confirmed that the hyper-thermal neutrons of approximately 860 K at maximum could be obtained by the generator. From the phantom experiment, the improvement effect and the controllability for the depth-dose distribution were confirmed. For example, it was found that the relative neutron depth-dose distribution was about 1 cm improved with the 860 K hyper-thermal neutron incidence, compared to the normal thermal neutron incidence. PMID:11197667

Sakurai, Y; Kobayashi, T

2001-01-01

361

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

SciTech Connect

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

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

1996-03-01

362

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

363

Early clinical experience of boron neutron capture therapy for glioblastoma multiforme  

SciTech Connect

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

Joel, D.D.; Bergland, R.; Capala, J. [and others

1995-12-31

364

Simultaneous Measurement of the Neutron Capture and Fission Yields of 233U  

SciTech Connect

We have measured the neutron capture and fission cross section of {sup 233}U at the neutron time-of-flight facility n{_}TOF at CERN in the energy range from 1 eV to 1 MeV with high accuracy by using a high performance 4{pi} BaF{sub 2} Total Absorption Calorimeter (TAC) as a detection device. The method, based on the TAC energy response study, allowing to disentangle between {gamma}'s originating from fission and capture will be presented as well as the first very preliminary results.

Berthoumieux, E. [CEA, Saclay, France; Koehler, Paul Edward [ORNL; Collaboration, n_TOF [Collaboration affiliations

2008-01-01

365

A proposed protocol for clinical trials of boron neutron capture therapy in glioblastoma multiforme  

SciTech Connect

Neutron capture therapy (NCT) was suggested in theory as a treatment for malignant tumors some 50 years ago. Since then considerable data have accumulated on the mechanisms of action and possible application of this technique. A comprehensive national boron neutron capture therapy (BNCT) research program at the Idaho National Engineering Laboratory (INEL) has been established directed toward further investigating this theory and toward validating (or invalidating) NCT as a treatment for human malignancy. As one component of this research program, a proposed protocol has been developed for a controlled study of the use of BNCT for the treatment of Glioblastoma Multiforme (GM). 1 fig.

Dorn, R.V. III; Spickard, J.H.; Griebenow, M.L.

1988-01-01

366

A proposed protocol for clinical trials of boron neutron capture therapy in glioblastoma multiforme  

SciTech Connect

Neutron Capture Therapy (NCT) was suggested in theory as a treatment for malignant tumors some 50 years ago. Since then, considerable data have accumulated on the mechanisms of action and possible application of this technique. This paper outlines a protocol for a controlled study of the use of Boron Neutron Capture Therapy (BNCT) for the treatment of Glioblastoma Multiforme (GM). The protocol is one component of a comprehensive national BNCT research program at the Idaho National Engineering Laboratory (INEL) directed towards validating (or invalidating) NCT as a treatment for human malignancies.

Dorn, R.V. III; Spickard, J.H.; Griebenow, M.L.

1988-01-01

367

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

368

Monte-Carlo simulation of primary stochastic effects induced at the cellular level in boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

A Monte Carlo code is developed to study the action of particles in Boron Neutron Capture Therapy (BNCT). Our aim is to calculate the probability of dissipating a lethal dose in cell nuclei. Cytoplasmic and nuclear membranes are considered as non-concentric ellipsoids. All geometrical parameters may be adjusted to fit actual configurations. The reactions 10B(n,??)^7Li and 14N(n,p)14C create heavy ions which slow down losing their energy. Their trajectories can be simulated taking into account path length straggling. The contribution of each reaction to the deposited dose in different cellular compartments can be studied and analysed for any distribution of 10B. Un code de simulation Monte-Carlo est développé pour étudier les modalités d'action de la Thérapie par Capture de Neutrons (TCN) sur le {10}B. L'objectif est le calcul de la probabilité de dépôt d'une dose létale dans les noyaux cellulaires. Les membranes cytoplasmique et nucléaire sont schématisées par des ellipsoïdes non concentriques dont tous les paramètres sont ajustables à des configurations réelles. Les réactions considérées, 10B(n,??)7 et 14N(n,p)14, produisent des ions dont les trajectoires peuvent être simulées en considérant les fluctuations sur les longueurs de parcours. Les contributions respectives de chaque réaction aux doses déposées dans les divers compartiments cellulaires peuvent être étudiées et analysées en fonction des distributions de 10B.

Cirioni, L.; Patau, J. P.; Nepveu, F.

1998-04-01

369

Dose point kernel for boron-11 decay and the cellular S values in boron neutron capture therapy.  

PubMed

The study of the radiobiology of boron neutron capture therapy is based on the cellular level dosimetry of boron-10's thermal neutron capture reaction 10B(n,alpha)7Li, in which one 1.47 MeV helium-4 ion and one 0.84 MeV lithium-7 ion are spawned. Because of the chemical preference of boron-10 carrier molecules, the dose is heterogeneously distributed in cells. In the present work, the (scaled) dose point kernel of boron-11 decay, called 11B-DPK, was calculated by GEANT4 Monte Carlo simulation code. The DPK curve drops suddenly at the radius of 4.26 microm, the continuous slowing down approximation (CSDA) range of a lithium-7 ion. Then, after a slight ascending, the curve decreases to near zero when the radius goes beyond 8.20 microm, which is the CSDA range of a 1.47 MeV helium-4 ion. With the DPK data, S values for nuclei and cells with the boron-10 on the cell surface are calculated for different combinations of cell and nucleus sizes. The S value for a cell radius of 10 microm and a nucleus radius of 5 microm is slightly larger than the value published by Tung et al. [Appl. Radiat. Isot. 61, 739-743 (2004)]. This result is potentially more accurate than the published value since it includes the contribution of a lithium-7 ion as well as the alpha particle. PMID:17278826

Ma, Yunzhi; Geng, JinPeng; Gao, Song; Bao, Shanglian

2006-12-01

370

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

PubMed

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 x 10(9) n cm(-2) s(-1) and 152, respectively. The maximum neutron flux inside the phantom was measured to be 2.79 x 10(9) 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. PMID:17440252

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

2007-04-17

371

Reaction Mechanism for p-Wave Neutron Capture in Mo92 and Mo98  

Microsoft Academic Search

A study of gamma-ray intensities following neutron capture in Mo92 and Mo98 provides evidence for a simple reaction mechanism which dominates the decay of the compound nuclear state. The intensities are largely accounted for by the motion of a valency neutron in transitions of the type p32-->d32, d52, or s12, and p12-->s12 or d32.

S. F. Mughabghab; R. E. Chrien; O. A. Wasson; G. W. Cole; M. R. Bhat

1971-01-01

372

Boron neutron capture therapy (BNCT) for high-grade gliomas of the brain: A cautionary note  

Microsoft Academic Search

Purpose\\/Objective: Boron neutron capture therapy (BNCT) is a method of treating high-grade gliomas of the brain that involves incorporating 10B into the tumor using appropriate phamacological agents and then irradiating the tumor with thermal or epithermal neutron beams. To date, over 120 patients have been treated in this manner by Japanese investigators using a thermal beam from a nuclear reactor.

George E. Laramore; Alexander M. Spence

1996-01-01

373

Boronated DNA-binding compounds as potential agents for boron neutron capture therapy.  

PubMed

Boron Neutron Capture Therapy (BNCT) is a binary cancer treatment that exploits the short range particles released from a nuclear fission reaction involving the non-radioactive 10B nucleus and low-energy (thermal) neutrons for the destruction of tumour cells. If boronated agents are targeted towards chromosomal DNA, the efficiency of BNCT is greatly enhanced. This article presents a concise review of DNA-binding compounds that have been functionalised with boron. PMID:17346220

Crossley, Ellen L; Ziolkowski, Erin J; Coderre, Jeffrey A; Rendina, Louis M

2007-03-01

374

Monte Carlo based dosimetry and treatment planning for neutron capture therapy of brain tumors  

Microsoft Academic Search

Monte Carlo based dosimetry and computer-aided treatment planning for neutron capture therapy have been developed to provide the necessary link between physical dosimetric measurements performed on the MITR-II epithermal-neutron beams and the need of the radiation oncologist to synthesize large amounts of dosimetric data into a clinically meaningful treatment plan for each individual patient. Monte Carlo simulation has been employed

R. G. Zamenhof; S. D. Clement; O. K. Harling; J. F. Brenner; D. E. Wazer; H. Madoc-Jones; J. C. Yanch

1990-01-01

375

Experimental test of the quasiparticle-phonon model in radiative capture of neutrons by deformed nuclei  

SciTech Connect

The IBR-30 pulsed reactor has been used to measure the ..gamma..-ray spectra accompanying capture of neutrons in isolated resonances of the nuclei /sup 154/Gd, /sup 171,173/Yb, and /sup 185/Re. Correlations between the partial radiative widths and the reduced neutron widths of the resonances are analyzed. Statistically reliable correlation effects are found. These effects fit into the framework of the quasiparticle-phonon model of Solov'ev.

Becvar, F.; Honzatko, J.; Kralik, M.; Dang Nhuan, N.; Stadnikov, T.; Telezhnikov, S.A.

1981-01-01

376

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

Microsoft Academic Search

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

1990-01-01

377

Power Burst Facility/Boron Neutron Capture Therapy Program for Cancer Treatment: Volume 4, No. 5  

SciTech Connect

Highlights of the Power Burst Facility Boron Neutron Capture Therapy (PBF/BNCT) Program during April 1990 include progress within areas of: gross boron analysis in tissue, blood, and urine; analytical methodologies development for BSH (Borocaptate Sodium) purity determination; 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 -- routine operations continue. 6 figs., 1 tab.

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

1990-05-01

378

Experimental test of the quasiparticle-phonon model in radiative capture of neutrons by deformed nuclei  

Microsoft Academic Search

The IBR-30 pulsed reactor has been used to measure the ..gamma..-ray spectra accompanying capture of neutrons in isolated resonances of the nuclei ¹⁵⁴Gd, \\/sup 171,173\\/Yb, and ¹⁸⁵Re. Correlations between the partial radiative widths and the reduced neutron widths of the resonances are analyzed. Statistically reliable correlation effects are found. These effects fit into the framework of the quasiparticle-phonon model of

F. Becvar; J. Honzatko; M. Kralik; N. Dang Nhuan; T. Stadnikov; S. A. Telezhnikov

1981-01-01

379

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

380

The stellar neutron capture rate of 138Ba.  

NASA Astrophysics Data System (ADS)

High resolution time of flight measurements of 138Ba(n, ?) were carried out at the pulsed electron linac GELINA in the energy range 0.5 - 300 keV and the stellar capture rate has been determined from the resonance parameters.

Beer, H.; Corvi, F.; Mauri, A.; Athanassopoulos, K.; Moxon, M. C.

1993-07-01

381

One-electron capture in slow collisions of highly charged ions with atoms  

Microsoft Academic Search

Some characteristic features of the one-electron capture process in the low- and medium-energy collisions of highly charged ions with atoms are considered within the electron tunneling model. The theoretical results are compared with the experimental data of Salzborn's group.

T. P. Grozdanov; R. K. Janev

1978-01-01

382

Multiple electron capture in slow collisions of highly charged ions with atoms  

Microsoft Academic Search

A short review of recent work is given. The present state of knowledge is then illustrated by discussing a selection of recently published experimental results in the framework of the molecular classical overbarrier model (MCBM). For this discussion the model is extended to allow the calculation of angular differential cross sections for well defined capture processes. Finally, several points of

A. Niehaus

1988-01-01

383

Proton emission following multiple electron capture in slow N{sup 7+}+HCl collisions  

SciTech Connect

Collisions between 98-keV N{sup 7+} ions and a HCl target have been investigated experimentally. The kinetic-energy distribution of fragment H{sup +} ions originating from multiple electron capture was detected at angles in the range 20 deg. -160 deg. with respect to the incident beam direction. Proton energies as large as 100 eV were observed, and calculations made in the simple Coulomb explosion model suggest that up to seven target electrons may be involved during the collision. Using the Landau-Zener model, we show that the N{sup 7+} projectile mainly captures outer-shell electrons from HCl. From the experimental data we derived multiple-capture cross sections which we compared with results from a model calculation made using the classical over-barrier model and also with a semiempirical scaling law. For the specific case of double capture, several structures appeared, which were assigned using ab initio calculations to states of HCl{sup 2+}.

Fremont, F.; Martina, D.; Kamalou, O.; Sobocinski, P.; Chesnel, J.-Y.; McNab, I.R.; Bennett, F.R. [Centre Interdisciplinaire de Recherche Ions Lasers, Unite Mixte CEA-CNRS-EnsiCaen-Universite de Caen Basse-Normandie, 6 boulevard du Mal Juin, F-14050 Caen Cedex (France); Physics, School of Natural Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU (United Kingdom); CSIRO Minerals, P.O. Box 90, Bentley, Western Australia 6982 (Australia)

2005-04-01

384

(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

385

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

SciTech Connect

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, R.G.

1990-01-01

386

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.

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

1997-01-01

387

Use of the power burst facility for boron neutron capture therapy  

SciTech Connect

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

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

1989-01-01

388

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

SciTech Connect

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

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

2008-01-01

389

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

390

Uger-electron spectroscopy in slow highly charged ion-atom collisions: Double capture and stabilization  

Microsoft Academic Search

The method of Auger electron spectroscopy was used to measure the cross sections for Auger decay of the configurations 3lnl? and 4lnl?(n⩾4) created in the collision system Ne10++He at impact energies ranging from 10 keV to 250 keV. Auger yields were calculated to convert the experimental cross sections for Auger-electron emission into the corresponding cross sections for double electron capture.

H. Merabet; J.-Y. Chesnel; F. Fre´mont; G. Cremer; C. Bedouet; X. Husson; D. Lecler; A. Spieler; M. Grether; N. Stolterfoht

1997-01-01

391

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

NASA Astrophysics Data System (ADS)

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

Hu, Jih-Perng; Rorer, David C.; Reciniello, Richard N.; Holden, Norman E.

2003-06-01

392

Photoneutron-induced, prompt neutron capture gamma-ray spectroscopy  

SciTech Connect

Many practical radioisotopic-based and accelerator-based nondestructive evaluation (NDE) methods using neutron-induced prompt gamma rays have been successfully developed for various applications during the last several decades. In addition, electron accelerator-based X-ray radiography has been well established for more than 100 yr. Combining the advantages of these two NDE technologies has been limited by the fact that most gamma-ray detectors are rendered ineffective by the intense bremsstrahlung photons (i.e., X-ray flash) associated with each electron accelerator pulse. In support of a U.S. Department of Energy project, the Idaho National Engineering and Environmental Laboratory (INEEL) is developing a prototype high-purity germanium (HPGe)-based NDE system that performs prompt gamma-ray spectroscopy for gamma rays acquired between accelerator-produced bremsstrahlung pulses. Using a 6.5-MeV electron accelerator and a beryllium metal photoneutron source, the acquired gamma-ray spectrum for an interrogated 2.7-kg block of NaCl is presented and compared to one obtained using a {sup 252}Cf neutron source. In addition, the predicted photoneutron source spectrum is compared to a typical {sup 252}Cf neutron source spectrum.

Jones, J.L.; Yoon, W.Y. [Idaho National Engineering and Environmental Lab., Idaho Falls, ID (United States)

1997-12-01

393

Combination of boron and gadolinium compounds for neutron capture therapy. An in vitro study.  

PubMed

In neutron capture therapy, the therapeutic effect of the boron compound is based on alpha particles produced by the B(n, alpha) reaction while with the gadolinium compound the main radiation effect is from gamma rays derived from the Gd(n, gamma) reaction. The uptake and distribution within the tumor may be different among these compounds. Thus, the combination of the boron and gadolinium compounds may be beneficial for enhancing the radiation dose to the tumor. Chinese hamster fibroblast V79 cells were used. For the neutron targeting compounds, 10B (BSH) at 0, 5, 10, and 15 ppm, and 157Gd (Gd-BOPTA) at 0, 800, 1600, 2400, 3200, and 4800 ppm, were combined. The neutron irradiation was performed with thermal neutrons for 30 min. (neutron flux: 0.84 x 10(8) n/cm2/s in free air). The combination of the boron and gadolinium compounds showed an additive effect when the gadolinium concentration was lower than 1600 ppm. This additive effect decreased as a function of gadolinium concentration at 2400 ppm and resulted in no additive effect at more than 3200 ppm of gadolinium. In conclusion, the combination of the boron and gadolinium compounds can enhance the therapeutic effect with an optimum concentration ratio. When the gadolinium concentration is too high, it may weaken the boron neutron capture reaction due to the high cross-section of gadolinium compound against neutrons. PMID:15943038

Matsumura, A; Zhang, T; Nakai, K; Endo, K; Kumada, H; Yamamoto, T; Yoshida, F; Sakurai, Y; Yamamoto, K; Nose, T

2005-03-01

394

10B-editing 1H-detection and 19F MRI strategies to optimize boron neutron capture therapy  

Microsoft Academic Search

Boron neutron capture therapy (BNCT) is a binary radiation therapy used to treat malignant brain tumours. It is based on the nuclear reaction (10B + nth ? [11B*] ? ? + 7Li + 2.79 MeV) that occurs when 10B captures a thermal neutron to yield ? particles and recoiling 7Li nuclei, both responsible of tumour cells destruction by short range

Silvia Capuani; Paola Porcari; Fabrizio Fasano; Renzo Campanella; Bruno Maraviglia

2008-01-01

395

The filter/moderator arrangement-optimisation for the boron-neutron capture therapy (BNCT).  

PubMed

The paper presents results of the numerical modelling of the fission-converter-based epithermal neutron source designed for the boron neutron capture therapy (BNCT) facility to be located at the Polish research nuclear reactor MARIA at Swierk. The unique design of the fission converter has been proposed due to a specific geometrical surrounding of the reactor. The filter/moderator arrangement has been optimised to moderate fission neutrons to epithermal energies and to remove both fast neutrons and photons from the therapeutic beam. The selected filter/moderator set-up ensures both high epithermal neutron flux and suitably low level of beam contamination. Photons originating from the reactor core are almost eliminated what is the exceptional advantage of the proposed design. It yields one order of magnitude lower gamma radiation dose than the maximum allowed dose in such a type of therapeutic facility. The MCNP code has been used for the computations. PMID:15353754

Tracz, G; Dabkowski, L; Dworak, D; Pytel, K; Wo?nicka, U

2004-01-01

396

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

397

One- and two-electron capture in collisions of slow B sup 4+ and Be sup 4+ ions with helium  

SciTech Connect

One-electron and two-electron capture in slow B{sup 4+}-He and Be{sup 4+}-He collisions are studied within the semiclassical close-coupling description with two-electron atomic basis sets. For B{sup 4+}-He collisions, we find large two-electron capture cross sections to 2{ital l}2{ital l}{prime} doubly excited projectile states. Double-capture cross sections to 2{ital s}{sup 2} {sup 1}{ital S{ital e}}, 2{ital s}2{ital p} {sup 1}{ital P{ital o}}, and 2{ital p}{sup 2} {sup 1}{ital D{ital e}} states and the relative {ital M} distributions are found to be in good agreement with recent experiments. Earlier data on B{sup 3+} production are found to contain large portions of double transfer followed by autoionization. For the Be{sup 4+}-He system, the summed cross sections from this work agree with an earlier theoretical study within the adiabatic model. Discrepancies remain, however, for this system in the distribution of double transfer over final states.

Fritsch, W. (Bereich Schwerionenphysik, Hahn-Meitner-Institut Berlin, D-1000 Berlin 39 (Germany)); Lin, C.D. (Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States))

1992-05-01

398

Potential of using boric acid as a boron drug for boron neutron capture therapy for osteosarcoma  

Microsoft Academic Search

Osteosarcoma is a malignant tumor commonly found in human and animals. The ability of boric acid (BA) to accumulate in osteosarcoma due to the mechanism of the bone formation of cancer cells would make boron neutron capture therapy (BNCT) an alternative therapy for osteosarcoma. This study evaluated the feasibility of using BA as the boron drug for BNCT of bone

C. F. Hsu; S. Y. Lin; J. J. Peir; J. W. Liao; Y. C. Lin; F. I. Chou

2011-01-01

399

Possible low-lying levels in /sup 165/Dy deduced from neutron capture. gamma. rays  

SciTech Connect

The high-energy thermal neutron capture ..gamma.. rays in /sup 165/Dy have been studied. Analysis has revealed 15 new levels below an excitation energy of 1650 keV in addition to 14 that were previously reported. The spins of the newly observed levels are most likely (1/2) or (3/2).

Islam, M.A.; Prestwich, W.V.; Kennett, T.J.

1983-05-01

400

On the calibration curve for determination of boron in tissue by quantitative neutron capture radiography  

Microsoft Academic Search

Quantitative neutron capture radiography (QNCR) is an imaging method to visualize the boron contents in biological samples such as whole body cryosections of small mammalians as well as cell cultures. One of the main problems of QNCR is calibration. In this paper an equation for the calibration curve for determination of boron in tissue by QNCR is developed. A comparison

Zeev B. Alfassi; Thomas U. Probst

1999-01-01

401

Rat Brain Tumor Models to Assess the Efficacy of Boron Neutron Capture Therapy: A Critical Evaluation  

Microsoft Academic Search

Development of any therapeutic modality can be facilitated by the use of the appropriate animal models to assess its efficacy. This report primarily will focus on our studies using the F98 and 9L rat glioma models to evaluate the effectiveness of boron neutron capture therapy (BNCT) of brain tumors. Following intracerebral implantation the biological behavior of each tumor resembles that

Rolf F. Barth; Weilian Yang; Jeffrey A. Coderre

2003-01-01

402

A Critical Assessment of Boron Target Compounds for Boron Neutron Capture Therapy  

Microsoft Academic Search

Boron neutron capture therapy (BNCT) has undergone dramatic developments since its inception by Locher in 1936 and the development of nuclear energy during World War II. The ensuing Cold War spawned the entirely new field of polyhedral borane chemistry, rapid advances in nuclear reactor technology and a corresponding increase in the number to reactors potentially available for BNCT. This effort

M. Frederick Hawthorne; Mark W. Lee

2003-01-01

403

License amendment for neutron capture therapy at the MIT research reactor  

Microsoft Academic Search

This paper reports the issuance by the U.S. Nuclear Regulatory Commission (NRC) of a license amendment to the Massachusetts Institute of Technology (MIT) for the use of the MIT Research Reactor's (MITR-II) medical therapy facility beam for the treatment of humans using neutron capture therapy (NCT). This amendment is one of 11 required approvals. The others are those of internal

1993-01-01

404

Capture Cross Sections of the Neon Isotopes and the S-Process Neutron Balance.  

National Technical Information Service (NTIS)

The neutron capture cross sections of the three stable neon isotopes have been measured by the time-of-flight method in the energy range from 5 to 200 keV, using hydrogen free fast liquid scintillator detectors and the Maier-Leibnitz pulse height weightin...

J. Almeida

1982-01-01

405

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

Microsoft Academic Search

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

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

2009-01-01

406

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

SciTech Connect

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

Glushkov, A. V. [Russian Academy of Sciences, Troitsk, Moscow reg., 142090 (Russian Federation); Odessa University, P.O. Box 24a, Odessa-9, South-East, 65009 (Ukraine); Malinovskaya, S. V.; Khetselius, O. Yu.; Loboda, A. V. [Odessa University, P.O. Box 24a, Odessa-9, South-East, 65009 (Ukraine)

2009-03-09

407

An international dosimetry exchange for boron neutron capture therapy, Part I: Absorbed dose measurements  

Microsoft Academic Search

An international collaboration was organized to undertake a dosimetry exchange to enable the future combination of clinical data from different centers conducting neutron capture therapy trials. As a first step (Part I) the dosimetry group from the Americas, represented by MIT, visited the clinical centers at Studsvik (Sweden), VTT Espoo (Finland), and the Nuclear Research Institute (NRI) at Rez (Czech

O. K. Harling; K. J. Riley; P. J. Binns; W. S. Kiger; P. M. Munck af Rosenscho?ld; V. Giusti; J. Capala; K. Sko?ld; I. Auterinen; T. Sere?n; P. Kotiluoto; J. Uusi-Simola; M. Marek; L. Viererbl; F. Spurny

2005-01-01

408

Power burst facility\\/boron neutron capture therapy program for cancer treatment. [Borocaptate sodium  

Microsoft Academic Search

Highlights of the Power Burst Facility\\/Boron Neutron Capture Therapy (PBF\\/BNCT) Program in November, 1990 are described. One of our major projects is support of technological development. In this area, progress has been seen in gross boron analysis of biological samples, higher purity borocaptate sodium (BSH), planning of experiments to investigate BSH biochemistry and oxidation products, bidding out for an ion

Dorn

1990-01-01

409

Selective boron drug delivery to brain tumors for boron neutron capture therapy  

Microsoft Academic Search

Malignant glioma is one of the most deadly forms of cancer in humans and remains refractory to presently available treatments. Boron neutron capture therapy (BNCT) is a promising therapeutic modality for the treatment of malignant brain tumors. For successful BNCT, a sufficient quantity of boron atoms must be selectively delivered to individual brain tumor cells while at the same time

Wei Chen; Samir C Mehta; D. Robert Lu

1997-01-01

410

Proton injection and RF capture in the national spallation neutron source.  

National Technical Information Service (NTIS)

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 affect...

A. U. Luccio J. Beebe-Wang D. Maletic

1997-01-01

411

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

412

Boron Neutron Capture Therapy: Effects of Split Dose and Overall Treatment Time  

Microsoft Academic Search

New clinical protocols are being developed that will entail the administration of considerably higher doses of the boron delivery agent boronophenylalanine (BPA) than those in current clinical use. Fractionation (2 or 4 fractions) of BPA mediated boron neutron capture therapy (BNCT) is also under consideration at some clinical centres. Given the considerably higher infusion volumes that will be entailed in

G. M. Morris; P. L. Micca; M. Rezvani; J. W. Hopewell; J. A. Coderre

2001-01-01

413

Ultrastructural localization of a neutron capture agent utilizing electron energy loss spectroscopy coupled with electron spectroscopic imaging  

SciTech Connect

Neutron capture therapy (NCT) is a binary therapeutic modality with significant potential for the treatment of localized tumors in humans. The NCT relies on selective uptake and/or retention within tumor of a nontoxic neutron capture agent (NCA) containing a neutron capture element such as {sup 10}B and irradiation of the tumor with an appropriate-energy neutron beam. The development of tumor-affinative capture agents is requisite for efficacious NCT, particularly those NCAs that specifically localize to vital organelles such as mitochondria and nuclei. Various methods have been utilized to determine tumor and normal tissue boron levels. Few, however, have successfully localized neutron capture elements, in vivo, at the ultrastructural level, which is crucial for determination of radiation microdosimetry. This paper describes experimental results of NCT on gliosarcomas in rats.

Autry, S.A.; Gandour-Edwards, R.; Boggan, J.E. [Univ. of California, San Francisco, CA (United States)] [and others

1995-12-31

414

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

SciTech Connect

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

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

2006-06-01

415

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

416

Neutron-capture cross sections from indirect measurements  

NASA Astrophysics Data System (ADS)

Cross sections for compound-nuclear reactions 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.

2012-02-01

417

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

418

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

419

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

NASA Astrophysics Data System (ADS)

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,?) measurements using the recently commissioned DANCE array.

Esch, E.-I.; Alpizar-Vicente, A.; Bond, E. M.; Bredeweg, T. A.; Glover, S. E.; Greife, U.; Haight, R. C.; Hatarik, R.; 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.

2005-05-01

420

Primary gamma transitions in 173,174Yb in neutron capture at isolated resonances  

NASA Astrophysics Data System (ADS)

Gamma transitions in 174Yb were investigated in radiative neutron capture at 23 isolated and additional 7 partially resolved summed resonances of 173Yb. The time-of-flight technique was used on an enriched target at the IBR-30 reactor at JINR Dubna. A total of 77 primary gamma transitions are reported populating levels in 174Yb up to 2.8 MeV in the spin parity range 1,2,3,4. Spin and parity assignments of neutron resonances and of populated levels are proposed. In addition to these results, seven primary gamma transitions in 173Yb were also observed from neutron capture at three isolated resonances of 172Yb.

Telezhnikov, S. A.; Granja, C.; Hiep, H. T.; Honzátko, J.; Králík, M.; Montero-Cabrera, M.-E.; Pospíšil, S.

2005-12-01

421

Fusion of time-dependent gamma production spectra from thermal neutron capture and fast neutron inelastic scattering to improve material detection  

Microsoft Academic Search

Neutron-based inspection techniques are unique in their ability to provide material specific signatures, thus offering very high performance and automatic detection of explosives and other contraband. Thermal neutron capture gamma spectroscopy provides excellent sensitivities to hydrogen, nitrogen, chlorine, and other elements, which are characteristic to most explosives, drugs and other contraband that may be smuggled into the country. Fast neutron

T. Gozani; M. Elsalim; D. Strellis; D. Brown

2003-01-01

422

Apparatus for reducing pulse pileup in an elemental analyzer measuring gamma rays arising from neutron capture in bulk substances  

Microsoft Academic Search

The active reduction of the number of analyzed events with pulse amplitudes which pileup has distorted improves measurement accuracy and response time in an apparatus for neutron-capture-based on-line elemental analysis of bulk substances. Within the apparatus, the analyzed bulk substance is exposed to neutrons, and neutron capture generates prompt gamma rays therefrom. A detector interacts with some of these gamma

1979-01-01