Note: This page contains sample records for the topic slow neutron capture from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Slow neutron capture gamma rays from samarium and gadolinium  

Microsoft Academic Search

Slow neutron capture gamma rays in the energy region below 1.5 MeV from samarium oxide and gadolinium oxide have been studied, employing a simple technique comprising a 2 curie polonium-beryllium neutron source and a single crystal scintillation spectrometer. The energies of the observed gamma components are estimated and compared with the values obtained by previous authors who have used reactors

D. L. Sastry; S. Jnanananda

1964-01-01

2

Comparative studies in direct slow-neutron capture calculations  

SciTech Connect

Primary E1 transitions due to thermal neutron capture by the nuclides /sup 9/Be, /sup 32,34/S, /sup 40,42,44,46,48/Ca, and /sup 58/Ni are quantitatively interpreted by the Lane-Lynn formula and are compared with recent optical model calculations. The two approaches are equivalent provided the internal region of the nucleus is excluded in the optical model approach. Theoretical justifications for such a procedure are briefly presented. 32 refs., 4 tabs.

Mughabghab, S.F.

1987-08-01

3

Gadolinium neutron capture therapy  

Microsoft Academic Search

A computer study of the dose distribution for gadolinium neutron capture therapy is carried out to determine its feasibility. Gadolinium is a potential neutron capture therapy (NCT) agent that produces gamma radiation, conversion electrons, and Auger electrons. The dose distribution from neutrons, neutron-induced gammas, and the reaction products from neutron capture in gadolinium were modeled using the Los Alamos National

G. A. Jr. Miller; N. E. Hertel; B. W. Wehring; J. L. Horton

1993-01-01

4

PHOTOGRAPHY OF SLOW NEUTRONS  

Microsoft Academic Search

Photographic emulsions are sensitive to photons and particles bearing ; electric charges but not to neutrons. To photograph neutrons a backing screen ; made of materials which would produce radioactivity through neutron capture is ; necessary, e.g., B (n, alpha ), Cd(n, gamma ), In(n, gamma ), Rh(n, gamma ); ; rhodium (Rh) has been the most favored material. The

K. Suen; F. Woo; T. Kuo

1961-01-01

5

Gadolinium neutron capture therapy  

SciTech Connect

A computer study of the dose distribution for gadolinium neutron capture therapy is carried out to determine its feasibility. Gadolinium is a potential neutron capture therapy (NCT) agent that produces gamma radiation, conversion electrons, and Auger electrons. The dose distribution from neutrons, neutron-induced gammas, and the reaction products from neutron capture in gadolinium were modeled using the Los Alamos National Laboratory Monte Carlo neutron photon computer code. The results of these calculations are that gadolinium has promise as an NCT agent. Using two parallel opposed epithermal neutron beams for a tumor at an 8.0-cm depth with a gadolinium loading of 100[mu]g/g, the tumor to peak normal tissue dose was determined to be 1.48.

Miller, G.A. Jr. (Univ. of Austin, TX (United States). Biomedical Engineering); Hertel, N.E. (Georgia Inst. of Technology, Atlanta, GA (United States). Mechanical Engineering); Wehring, B.W. (Univ. of Texas, Austin, Tx (United States). Mechanical Engineering); Horton, J.L. (Univ. of Texas, Houston, TX (United States). M.D. Anderson Cancer Center)

1993-09-01

6

Neutron capture therapies  

DOEpatents

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

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

1999-01-01

7

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

8

Accelerators and Neutron Capture Therapy  

Microsoft Academic Search

Within the frame of Accelerator Based Boron Neutron Capture Therapy (AB-BNCT), the Li(\\/?,n)7Be reaction, relatively near its energy threshold is one of the most promising, due to its high yield and low neutron energy. In this work a thick LiF target irradiated with a proton beam was studied as a neutron source. The 1.88-2.0 MeV proton beam was produced by

lDepartamento de Fisica

9

On-line beam monitoring for neutron capture therapy at the MIT Research Reactor  

Microsoft Academic Search

Neutron capture therapy sets new requirements on the measurement and monitoring of the radiation fields used in this new form of therapy. Beams used for neutron capture therapy are comprised of mixed radiation fields which include slow, epithermal, and fast neutrons, as well as gamma rays. A computer-based beam monitoring system for epithermal or thermal neutron capture therapy is described.

Otto K. Harling; Damien J. Moulin; Jean-Michel Chabeuf; Guido R. Solares

1995-01-01

10

Experiments with a Slow Neutron Velocity Spectrometer  

Microsoft Academic Search

Neutron bursts were produced by modulation of the arc source of a small cyclotron. Neutrons subsequently slowed down in paraffin were detected by a BF3 ionization chamber and linear amplifier. Modulation of an additional amplifier allowed the counting of all detected neutrons as well as those arriving in a specified time interval. Time of flight experiments were carried out at

C. P. Baker; R. F. Bacher

1941-01-01

11

Neutron slowing-down time in matter  

NASA Astrophysics Data System (ADS)

We formulate the neutron slowing-down time through elastic collisions in a homogeneous, non-absorbing, infinite medium. Our approach allows taking into account for the first time the energy dependence of the scattering cross-section as well as the energy and temporal distribution of the source neutron population in the results. Starting from this development, we investigate the specific case of the propagation in matter of a mono-energetic neutron pulse. We then quantify the perturbation on the neutron slowing-down time induced by resonances in the scattering cross-section. We show that a resonance can induce a permanent reduction of the slowing-down time, preceded by two discontinuities: a first one at the resonance peak position and an echo one, appearing later. From this study, we suggest that a temperature increase of the propagating medium in presence of large resonances could modestly accelerate the neutron moderation.

Chabod, Sbastien P.

2012-03-01

12

Gadolinium as a Neutron Capture Therapy Agent  

Microsoft Academic Search

The clinical results of treating brain tumors with boron neutron capture therapy are very encouraging and researchers around the world are once again making efforts to develop this therapeutic modality. Boron-10 is the agent receiving the most attention for neutron capture therapy but ^{157}Gd is a nuclide that also holds interesting properties of being a neutron capture therapy agent. The

Jing-Luen Allen Shih

1991-01-01

13

Angular correlations in fission of unpolarized nuclei by slow neutrons  

SciTech Connect

We consider the P-even correlations kxp and sigmaxk x p that arise on fission of unpolarized nuclei by slow neutrons (sigma and k are the spin and momentum of the neutron, and p is the momentum of the light fragment). The effect is due to interference of the neutron-capture s and p amplitudes. The estimates of the correlations agree with the experimental data. Observation of these correlations at the expected level attests to the correctness of the previously considered mechanism of parity violation in fission.

Sushkov, O.P.; Flambaum, V.V.

1981-03-01

14

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

15

A note on the isotopic assignment of slow neutron resonances in Samarium, Iridium and Gadolinium  

Microsoft Academic Search

Some further isotopic assignments of slow neutron resonances have been ; made with the elements samarium, iridium, and gadoliniuma using tbe Harwell 15 ; Mev linear accelerator and capture gamma ray scintillation detectors.;

E. M. Bowey; J. R. Bird

1958-01-01

16

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

17

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

18

Halo Effect on Direct Neutron Capture Process  

Microsoft Academic Search

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

Zu-Hua Liu; Hong-Yu Zhou

2004-01-01

19

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

20

Neutron captures and the r-process  

NASA Astrophysics Data System (ADS)

In order to study possible neutron-capture effects during an r-process, it is necessary to perform fully dynamical simulations. We have performed such calculations within the model of an adiabatically expanding high-entropy bubble of a SN II, using temperature-dependent reaction rates including the NON-SMOKER neutron-capture rates of Rauscher et al..

Farouqi, K.; Kratz, K.-L.; Pfeiffer, B.; Rauscher, T.; Thielemann, F.-K.

2006-03-01

21

Boron Neutron Capture Therapy for Cancer  

Microsoft Academic Search

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

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

1990-01-01

22

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?v?, F.; Krti?ka, M.

2012-02-01

23

Polarized Cold Neutron Capture in ^27Al  

NASA Astrophysics Data System (ADS)

The NPDGamma Experiment at the Spallation Neutron Source at ORNL is measuring the parity-odd correlation between the neutron spin and the direction of the emitted photon in the capture of cold neutrons on a 16-liter liquid parahydrogen target. The goal is to determine the strength of the weak nucleon-nucleon interaction. One of the main background contributions comes from the gamma rays produced by neutrons captured in the Al walls of the target vessel. To quantify this effect a commissioning experiment measured the parity-odd and parity-even asymmetries in the angular distribution of the gamma rays from the capture of polarized cold neutrons in a solid Al target. A status of the analysis of this experiment will be presented.

Balascuta, Septimiu

2013-04-01

24

Gadolinium as a neutron capture therapy agent.  

PubMed

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

Shih, J L; Brugger, R M

1992-01-01

25

Neutron capture in the r-process  

SciTech Connect

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

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

2010-01-01

26

Neutron Capture gamma-Ray Facility.  

National Technical Information Service (NTIS)

A neutron capture gamma-ray facility was constructed for prompt gamma-ray spectrometry, and its characteristics were measured. In the facility, a neutron beam is extracted from the H-6 horizontal experimental hole of Japan Research Reactor No.3, JAERI, an...

T. Tojo C. Yonezawa S. Koura S. Arai T. Komori

1980-01-01

27

Neutron-Proton Capture Cross Section  

Microsoft Academic Search

The mean lifetime of thermal neutrons in water is measured with a large moderator (radius ~7 diffusion lengths), for which the correction for escape is only about 5%. The geometry is such that the perturbing effect of the immersed BF3 neutron detector can be almost rigorously calculated. The value obtained is tau=206.3+\\/-5.0 musec, giving the neutron-proton capture cross section as

Robert W. Stooksberry; Marshall F. Crouch

1959-01-01

28

Neutron capture therapy research in Australia  

SciTech Connect

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

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

1989-07-01

29

Neutron capture therapy research in Australia.  

PubMed

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

Allen, B J

1989-01-01

30

Neutron-Resonance Capture Analysis of Materials  

SciTech Connect

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

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

1999-11-14

31

Low energy neutron capture of neutron-rich target nuclides  

Microsoft Academic Search

We have used nuclear model codes developed at ENEA, Bologna, Italy, to calculate (n, gamma) capture cross sections on 76 neutron-rich nuclides. The physics models used and the method of obtaining relevant input parameters are summarized.

Gianni Reffo; M. Blann; T. Komoto; R. J. Howerton

1988-01-01

32

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

33

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

Microsoft Academic Search

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

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

1975-01-01

34

Gadolinium as a Neutron Capture Therapy Agent  

NASA Astrophysics Data System (ADS)

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

Shih, Jing-Luen Allen

35

Thermal-neutron capture by 14N  

Microsoft Academic Search

The energies and intensities of 58 gamma rays emitted in thermal-neutron capture by nitrogen (99.63% 14N) have been measured accurately. A major reason was to establish this reaction as a standard for similar measurements on other nuclides. These gamma rays have been placed between 19 known levels (including the ground state and the capturing state) in 15N. The primary gamma

E. T. Jurney; J. W. Starner; J. E. Lynn; S. Raman

1997-01-01

36

DYNAMICAL CAPTURE BINARY NEUTRON STAR MERGERS  

SciTech Connect

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

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

2012-11-20

37

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

38

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

39

Thermal-neutron capture in light nuclei  

SciTech Connect

We have made considerable progress toward the goal of carrying out thermal-neutron capture {gamma}-ray measurements on all stable isotopes below A=60. Information processed till now has significantly augmented the existing knowledge on the detailed nuclear level structure of many light nuclides. Most of this knowledge comes from our {gamma}-ray energies, level placements, and branching ratios of secondary transitions between low-lying states. Spectroscopic information is also contained in the cross sections of the primary transitions originating from the capturing state. This is deduced from the success of ``direct`` theories of neutron capture for many nuclides, especially those of light and near closed-shell character. 23 refs, 1 tab, 3 figs.

Raman, S. [Oak Ridge National Lab., TN (United States); Jurney, E.T.; Lynn, J.E. [Los Alamos National Lab., NM (United States)

1996-10-01

40

Electron capture rates for neutron star crusts  

NASA Astrophysics Data System (ADS)

In the study of the crust of an accreting neutron star, electron capture rates on nuclei in the mass range A=20-106 from the neutron deficient region to the neutron drip line are needed. At the low temperatures typical of a neutron star crust (T9 0.4) the determination of the phase space poses a problem since the integrand is very sharply peaked and an error in finding the peak using numerical differentiation or cruder maximum-locator methods will result in inaccuracies at the energies where the integrand has its highest value. In this work we present a global set of temper- ature and density-dependent continuum electron capture rates and a fast phase space calculator valid for low temperatures. The electron capture rates have been calculated using Gamow-Teller strength distributions from the quasi-particle random-phase approximation (QRPA, [1]) nuclear model. We present a new analytic technique to carry out the evaluation of the phase space for electron capture that is fast enough to be implemented in a reaction network. The integral is split into two separate terms at the chemical potential of the electron gas, thus eliminating the need to find the peak of the integrand. The Coulomb correction, which is essentially constant over the range of energies considered, is taken outside the integral and is evaluated at a suitable effective energy which is a function of the charge of the capturing nucleus, the temperature, the chemical potential and the threshold. We compare our calculated electron capture rates to the compilations by Fuller, Fowler and Newman [2] and by Langanke and Martnez-Pinedo [3].

Becerril Reyes, Ana Delia; Gupta, S.; Schatz, S.; Kratz, K. L.; Mller, P.

41

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

42

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

43

MEASUREMENTS OF RADIATIVE CAPTURE CROSS SECTIONS FOR FAST NEUTRONS  

Microsoft Academic Search

Cross-section measurements of radiative capture were made both for ; monoenergetic fast neutrons and for a wide spectra of fast neutrons by means of ; an activation method, as well as by neutron halance in the spherical geometry of ; the experiment, by capture gamma rays, and by reactivity measurements. ; Measurements of capture cross sections for a number of

A. I. Leipunskii; O. D. Kazachkovskii; G. Y. Artyukov

1959-01-01

44

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

45

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

46

Preparation of radioactive rare earth targets for neutron capture study  

SciTech Connect

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

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

2002-01-01

47

Thermal Neutron Capture y's (CapGam)  

DOE Data Explorer

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

48

Accelerator-driven boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

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

Edgecock, Rob

2014-05-01

49

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

SciTech Connect

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

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

1994-03-30

50

Slow neutron imaging using scintillating glass optical fibers  

Microsoft Academic Search

The performance of a slow neutron area detector, based on a scintillating glass fiber plate coupled to an intensified CCD, at room temperature, is reported. In the preliminary test single neutron events are detected with a spatial resolution of ~ 100 mum (FWHM). Possible improvements are discussed.

P. Ottonello; G. A. Rottigni; G. Zanella; R. Zannoni

1994-01-01

51

Neutron Capture Experiments Using the DANCE Array at Los Alamos  

Microsoft Academic Search

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

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

2009-01-01

52

Boron neutron capture enhancement of fast neutron radiotherapy  

NASA Astrophysics Data System (ADS)

Clinical trials have revealed a therapeutic advantage for fast neutron radiation over conventional photon radiation for salivary gland cancer, prostate cancer, sarcoma, and a subgroup of lung cancer. Conversely, fast neutron treatment of high grade astrocytic brain tumors [glioblastoma multiforme (GBM)] resulted in tumor sterilization, but also caused significant brain injury such that no therapeutic gain was attained. This effect was important, however, in that photon radiation and other conventional treatments have not demonstrated sterilization of GBM at any dose. Recent laboratory studies demonstrated that the hospital-based fast neutron beam from the University of Washington cyclotron has a thermal neutron component that may be used in a boron-10 neutron capture (BNC) reaction to enhance cell kill. The degree of enhancement was approximately 10 fold, and was dependent upon the boron-10 concentration, the boron-10 carrier agent, and the fast neutron dose per fraction. The results of these experiments will be discussed in the context of creating a therapeutic window for treatment of glioblastoma using BNC-enhanced fast neutron radiation in a clinically tolerable regimen.

Stelzer, K. J.; Laramore, G. E.; Risler, R.; Wiens, L.; Griffin, T. W.

1997-02-01

53

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

54

Optimization of boron and neutron delivery for neutron capture therapy  

SciTech Connect

A number of groups in the United States have received funding that will permit evaluation of the clinical efficacy of the neutron capture therapy (NCT) procedure. Various reactors are being modified to allow the construction of an epithermal neutron beam. At the Brookhaven Medical Research Reactor (BMRR), the patient irradiation facility is being modified to produce an optimized epithermal neutron beam. An 80-cm-thick A1-D2O mixture (184 g/cm2, 25% D2O by volume) is being installed in the shutter assembly. One-dimensional calculations indicate that this configuration should provide an epithermal neutron flux density of approximately 1 x 10(9) n/cm2/sec at 3 MW and a concomitant fast neutron dose rate of approximately 2 x 10(-11) rad per epithermal neutron (assuming a homogeneous A1-D2O mixture). The actual geometry will be an inhomogeneous array of D2O and A1 layers producing parameters somewhat less favorable than those listed above; experimental verification is in progress. Significant gains have recently been made in selectively targeting B to melanoma with various melanaffinic compounds, including p-boronophenylalanine, and with boronated porphyrins that may be applicable to a variety of tumors. Neutron capture radiographs have been obtained with the above compounds, and efforts have been made to quantitate boron uptake in growing and quiescent or necrotic regions of tumor via double-labeling techniques obtained with tritiated thymidine. A correlation between therapeutic efficacy and the ability to deliver boron to viable areas of tumor has been observed.

Fairchild, R.G.; Slatkin, D.N.; Coderre, J.A.; Micca, P.L.; Laster, B.H.; Kahl, S.B.; Som, P.; Fand, I.; Wheeler, F. (Brookhaven National Lab., Upton, NY (USA))

1989-07-01

55

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

56

GAMMA RAY ENERGY SPECTRA FROM THERMAL NEUTRON CAPTURE  

Microsoft Academic Search

Energy spectra of gamma rays resulting from thermal neutron capture are ; compiled for 48 elements. The data are presented in both graphical and tabular ; form. Thermal-neutron-capture cross sections, isotopic abundances, binding ; energies of the extra neutron in the isotopes, and weighted-average binding ; energies are also tabulated. (auth);

Deloume

1958-01-01

57

GAMMA RAY ENERGY SPECTRA FROM THERMAL NEUTRON CAPTURE  

Microsoft Academic Search

Energy spectra of gamma rays resulting from thermal neutron capture are ; compiled for forty-nine elements. The data are presented in both graphical and ; tabular form. Thermal neutron capture cross sections, isotopic abundances, ; binding energies of the extra neutron in the isotopes, and weighted average ; binding energies are also tabulated. (auth);

Deloume

1958-01-01

58

Boron neutron capture in prostate cancer cells.  

PubMed

A modified enhanced thermal neutron beam (METNB) assembly at Fermilab was used to irradiate borylphenylalanine (BPA) treated human prostate cancer cells, DU 145. Acceptable cellular uptake levels of BPA and no BPA cytotoxicity were observed. In the absence of BPA, the relative biological effectiveness (RBE) of the METNB was determined to be 2.3-4.8 times greater than gamma rays. An additional 1.2 or 1.4 fold relative enhancement from boron neutron capture (RE(BNC)) was observed for METNB irradiated DU 145 cells treated with 4.9 or 12mM BPA, respectively. The additional cell killing of the BPA loaded DU 145 cells by the METNB at Fermilab is evidence for a BNC enhanced cell killing. PMID:21784649

Yasui, Linda; Kroc, Thomas; Gladden, Samantha; Andorf, Christine; Bux, Sajit; Hosmane, Narayan

2012-01-01

59

Capture of Cold Neutrons by ^208Pb  

NASA Astrophysics Data System (ADS)

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

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

1998-10-01

60

Capture Gamma-ray Spectroscopy Using Cold Neutron Beams  

NASA Astrophysics Data System (ADS)

The availability of cold neutron beams can improve the quality of results obtainable from a capture gamma-ray measurement. Although capture gamma-ray instruments that use cold neutrons are less susceptible to problems that limit the capabilities of thermal instruments, new design parameters become important to consider. We discuss some of the questions that relate to neutron beam handling and present techniques for improving the quality of the capture gamma-ray instrument.

Stone, C. A.; Mildner, D. F. R.; Zeisler, R.; Cranmer, D. C.

1991-10-01

61

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

Microsoft Academic Search

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

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

2009-01-01

62

Neutron Capture Experiments Using the DANCE Array at Los Alamos  

SciTech Connect

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

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

2009-03-31

63

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

64

Progress in neutron capture therapy for cancer  

SciTech Connect

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

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

1992-09-01

65

Progress in neutron capture therapy for cancer  

SciTech Connect

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

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

1992-01-01

66

Neutron Capture Gamma-Ray Libraries for Nuclear Applications  

Microsoft Academic Search

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

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

2011-01-01

67

Neutron Capture Gamma-Ray Libraries for Nuclear Applications  

Microsoft Academic Search

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

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

2010-01-01

68

Neutron induced capture and fission discrimination using calorimetric shape decomposition  

NASA Astrophysics Data System (ADS)

The neutron capture and fission cross-sections of 233U have been measured at the neutron time-of-flight facility n_TOF at CERN in the energy range from 1 eV to 1 keV using a high performance 4? BaF2 Total Absorption Calorimeter (TAC) as a detection device. In order to separate the contributions of neutron capture and neutron induced fission in the TAC, a methodology called Calorimetric Shape Decomposition (CSD) was developed. The CSD methodology is based on the study of the TAC's energy response for all competing reactions, allowing to discriminate between ? s originating from neutron induced fission and those from neutron capture reactions without the need for fission tagging or any additional detection system. In this article, the concept behind the CSD is explained in detail together with the necessary analysis to obtain the TAC's response to neutron capture and neutron induced fission. The discrimination between capture and fission contributions is shown for several neutron energies. A comparison between the 233U neutron capture and fission yield extraction with ENDF/B-VII v1. library data is also provided.

Carrapio, C.; Berthoumieux, E.; Dridi, W.; Gonalves, I. F.; Gunsing, F.; Lampoudis, C.; Vaz, P.; n TOF Collaboration

69

Method of using gadolinium neutron capture to treat cancers  

US Patent & Trademark Office Database

Described is a method of using gadolinium-containing compounds as agents for neutron capture therapy to treat neoplastic cell growth. The subject is exposed to a gadolinium-containing compound for a time sufficient to allow the compound to accumulate in neoplastic cells. The subject is then exposed to a thermal and/or epithermal neutron flux, thereby initiating a neutron capture reaction in the gadolinium atoms that results in specific death of neoplastic cells.

2004-08-03

70

Thermal Neutron Capture Cross Sections Of The Palladium Isotopes  

Microsoft Academic Search

We have measured precise thermal neutron capture gamma-ray cross sections cry for all stable Palladium isotopes with the guided thermal neutron beam from the Budapest Reactor. The data were compared with other data from the literature and have been evaluated into the Evaluated Gamma-ray Activation File (EGAF). Total radiative neutron capture cross-sections sigmagamma can be deduced from the sum of

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

2006-01-01

71

Thermal Neutron Capture Cross Sections of The Palladium Isotopes  

Microsoft Academic Search

We have measured precise thermal neutron capture γ-ray cross sections {sub γ} 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)[1]. Total radiative neutron capture cross-sections can be deduced from the sum

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

2005-01-01

72

Updates for Gadolinium neutron capture measurements at DANCE  

Microsoft Academic Search

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

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

2007-01-01

73

Neutron capture therapy with deep tissue penetration using capillary neutron focusing  

DOEpatents

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

Peurrung, Anthony J. (Richland, WA)

1997-01-01

74

Measurement of the Effective Neutron Capture Cross Section of Cesium134 by Triple Neutron Capture Reaction Method  

Microsoft Academic Search

The measurement of effective neutron capture cross section() of Cs was carried out with a method using a triple neutron capture reaction,Cs(n, ?)Cs(n,?)Cs(n, ?)Cs. The target used for the experiment was natural cesium(Cs), and was irradiated for 23 days and 17 hours in the reactor JRR-3 at Japan Atomic Energy Research fnstitute(JAERI). The neutron field of the reactor was monitored

Toshio KATOH; Shoji NAKAMURA; Hideo HARADA; Yuichi HATSUKAWA; Nobuo SHINOHARA; Kentaro HATA; Katsutoshi KOBAYASHI; Shoji MOTOISHI; Masakazu TANASE

1999-01-01

75

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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

Miura, M.; Slatkin, D.N.

1997-08-05

76

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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

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

1995-10-03

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

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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

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

1997-08-05

79

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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

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

1997-03-18

80

Halogenated sulfidohydroboranes for nuclear medicine and boron neutron capture therapy  

DOEpatents

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

Miura, M.; Slatkin, D.N.

1997-03-18

81

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

82

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. 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.; Summers, N.; Escher, J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Firestone, R. B.; Basunia, S. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Hurst, A. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Krticka, M. [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Prague 8 (Czech Republic); Molnar, G.; Belgya, T.; Revay, Z. [Institute of Isotope and Surface Chemistry, H-1525, Budapest (Hungary); Choi, H. D. [Seoul National University, Republic of Korea and Department of Physics, University of Hankook, Seoul, 120-424 (Korea, Republic of)

2011-06-28

83

Neutron Capture Reactions on lu Isotopes at Dance  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

84

Scintillating glass for the detection of slow neutrons  

Microsoft Academic Search

A scintillating glass was prepared and investigated. The glass, with the composition Li2O. 2SiO2(Ce) may be used for the detection of slow neutrons. The scintillation efficiency of the glass relative to NaI(Tl) under electron excitement, was 1.4%. The ratio of the scintillation yields for electrons and a-particles was 3.84. The de-excitation time constant was ~0.15 sec. The efficiency of glass

V. K. Voitovetskii; N. S. Tolmacheva; M. I. Arsaev

1960-01-01

85

Nuclear Fuel Materials Analysis Using Thermal Neutron Capture gamma Rays.  

National Technical Information Service (NTIS)

Concentrations of impurities of burnable poisons in reactor fuel materials which are not possible to detect with conventional methods of analysis were determined by measuring the prompt gamma rays following thermal neutron capture, in a reactor internal g...

B. R. S. Pecequilo A. A. Suarez

1985-01-01

86

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

87

Cascade ? rays following capture of thermal neutrons on 113Cd  

NASA Astrophysics Data System (ADS)

Intensity distributions of cascade ?-ray transitions following the capture of thermal neutrons by 113Cd have been measured at the Los Alamos Neutron Science Center for various ?-ray multiplicities. The experiment was carried out at the highly segmented 4? ?-ray calorimeterDetector for Advanced Neutron Capture Experiments (DANCE). A measured two-dimensional spectrum of counts versus ?-ray energy versus ?-ray multiplicity, from the strongest resonance in the 113Cd(n,?) reaction at 0.178 eV has been compared to predictions from the statistical model. The best representation of the ?-ray cascades following the capture of thermal neutrons on 113Cd is presented. The intensity distribution of these cascades is of great importance for estimates of response to thermal neutrons of devices that use natural or enriched cadmium.

Rusev, G.; Jandel, M.; Krti?ka, M.; Arnold, C. W.; Bredeweg, T. A.; Couture, A.; Moody, W. A.; Mosby, S. M.; Ullmann, J. L.

2013-11-01

88

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

89

Performance of silicon microdosimetry detectors in boron neutron capture therapy  

Microsoft Academic Search

Bradley, P.D., Rosenfeld, A.B , Allen, B, Coderre, J., and Capala, J, Performance of silicon microdosimetry detectors in boron neutron capture therapy Reverse-biased silicon p-n junction arra ys using Silicon-On-Insulator technology have been proposed as microdosimeters. The performance of such detectors in boron neutron capture therapy (BNCT) is discussed. This work provides the first reported measurements using boron coated silicon

Peter D. Bradley; Anatoly B. Rosenfeld; Barry Allen

1999-01-01

90

Fission Reactor Neutron Sources for Neutron Capture Therapy A Critical Review  

Microsoft Academic Search

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,

Otto K. Harling; Kent J. Riley

2003-01-01

91

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

92

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

93

Stellar neutron capture cross sections of the Gd isotopes.  

National Technical Information Service (NTIS)

The neutron capture cross sections of (sup 152)Gd, (sup 154)Gd, (sup 155)Gd, (sup 156)Gd, (sup 157)Gd, and (sup 158)Gd 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 (...

K. Wisshak F. Voss F. Kaeppeler K. Guber L. Kazakov

1995-01-01

94

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

95

Conceptual design of a medical reactor for neutron capture therapy  

Microsoft Academic Search

A conceptual design of a passively safe reactor facility for boron neutron capture therapy is presented. The facility configuration and its neutronic, thermal hydraulic, and safety issues are addressed in order to demonstrate the deployability of reactor technology for routine patient treatments and advanced research and dosimetry. The reactor has a power level of <10 MW (thermal) and is based

W. A. Neuman; J. L. Jones

1990-01-01

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

Neutron capture studies of 206Pb at a cold neutron beam  

NASA Astrophysics Data System (ADS)

Gamma-ray transitions following neutron capture in 206Pb have been studied at the cold neutron beam facility of the Budapest Neutron Centre using a metallic sample enriched in 206Pb and a natural lead nitrate powder pellet. The measurements were performed using a coaxial HPGe detector with Compton suppression. The observed -rays have been incorporated into a decay scheme for neutron capture in 206Pb . Partial capture cross sections for 206Pb(n,) at thermal energy have been derived relative to the cross section for the 1884keV transition after neutron capture in 14N . From the average crossing sum a total thermal neutron capture cross section of mb was derived for the 206Pb(n,) reaction. The thermal neutron capture cross section for 206Pb has been compared with contributions due to both direct capture and distant unbound s-wave resonances. From the same measurements a thermal neutron-induced capture cross section of mb was determined for the 207Pb(n,) reaction.

Schillebeeckx, P.; Belgya, T.; Borella, A.; Kopecky, S.; Mengoni, A.; Qutel, C. R.; Szentmiklsi, L.; Trel, I.; Wynants, R.

2013-11-01

98

Neutron capture therapy with deep tissue penetration using capillary neutron focusing  

DOEpatents

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

Peurrung, A.J.

1997-08-19

99

SLOW-NEUTRON SPECTRUM MEASUREMENTS FROM THE SWEDISH HEAVY-WATER REACTOR, R1  

Microsoft Academic Search

During the last-few months a slow chopper with associated time-of-flight ; equipment has been put into operation at the Swedish reactor, R1. The first task ; was to determine the shape of the slow neutron spectrum in the wavelength region ; from 0.85 to 11 A. The spectrum of the slow neutrons emerging from an ; experimental hole is best

K. E. Larsson; R. Stedman; H. Palevsky

1958-01-01

100

Measurement of internal conversion electrons from Gd neutron capture  

NASA Astrophysics Data System (ADS)

Gadolinium (Gd) is a suitable material for neutron conversion because of its superior neutron absorption cross-section. However, the principal secondary particles that generate electron-hole pairs in a semiconductor detector after Gd neutron capture are low-energy internal conversion (IC) electrons. We measured the IC electron spectrum due to Gd neutron capture by using a thermal neutron beam and a digitizer-based multidetector spectroscopy. We also discussed the effective use of the IC electrons in the context of a twin-detector design and the associated gamma-ray rejection issues. Extensive simulations of the spectra of IC electrons and gamma rays agreed well with the experimental results; both types of results support the feasibility of the proposed n-? separation method.

Kandlakunta, P.; Cao, L. R.; Mulligan, P.

2013-03-01

101

Cosmogenic neutron-capture-produced nuclides in stony meteorites  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

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

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

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

Analytical use of neutron-capture gamma-rays  

Microsoft Academic Search

Certain elements which are not possible to detect with conventional neutron activation analysis can be measured using thermal\\u000a neutron-capture gamma-ray analysis. The use of a curved neutron guide at the High Flux Reactor, Grenoble, with a thermal neutron\\u000a flux of 1.51010ncm?2sec?1 and the advantage of a low-background counting system (Ge(Li) detector) far from the reactor core are described. Experimental\\u000a detection

R. Henkelmann; H.-J. Born

1973-01-01

106

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

107

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

Microsoft Academic Search

An accelerator-based neutron irradiation facility employing an electrostatic quadrupole (ESQ) accelerator for Boron Neutron Capture Therapy (BNCT) has been proposed at Lawrence Berkeley National Laboratory. In this dissertation, the properties of an ideal neutron beam for delivering a maximized dose to a glioblastoma multiforme tumor in a reasonable time while minimizing the dose to healthy tissue is examined. A variety

Darren Leo Bleuel

2003-01-01

108

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

Microsoft Academic Search

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 minimized. Calculations for ANSTO's 10 MW research reactor HIFAR have shown that, even though a filter material such as

BAIBA V. HARRINGTON

1989-01-01

109

Neutron Capture and Fission Measurement on ^238Pu at DANCE  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

110

Neutron capture on Sm-149 in lunar samples.  

NASA Technical Reports Server (NTRS)

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

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

1971-01-01

111

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

112

Nonstatistical effects of neutron radiative capture in deformed nuclei  

SciTech Connect

The present review summarizes experimental results on neutron radiative capture in deformed nuclei at isolated resonances. For /sup 154/Gd, /sup 167/Er, /sup 173/Yb, /sup 176/Lu, /sup 185/Re target nuclei a statistically significant correlation between the partial radiation widths and the reduced neutron widths of neutron resonances has been observed. These results are compared with predictions of the theory of Lane and Lynn, as well as with qualitative predictions following from Soloviev's model. Some consequencies of a large effect of correlation are discussed in detail. In case of neutron radiative capture in /sup 173/Yb a strong correlation between various partial radiation widths has been observed. It is concluded that a doorway state common to radiation channels is responsible for this effect.

Becvar-hacek, F.

1985-01-15

113

Improved Neutron-Capture Element Abundances in Planetary Nebulae  

Microsoft Academic Search

Spectroscopy of planetary nebulae (PNe) provides the means to investigate s-process enrichments of neutron(n)-capture elements that cannot be detected in Asymptotic Giant Branch (AGB) stars. However, accurate abundance determinations of these elements present a challenge. Corrections for unobserved ions can be large and uncertain, since in many PNe only one ion of a given n-capture element has been detected. Furthermore,

N. C. Sterling; H. L. Dinerstein; S. Hwang; S. Redfield; A. Aguilar; M. C. Witthoeft; D. Esteves; A. L. D. Kilcoyne; M. Bautista; R. Phaneuf; R. C. Bilodeau; C. P. Ballance; B. McLaughlin; P. H. Norrington

2009-01-01

114

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

115

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)

1993-07-01

116

Fission reactor neutron sources for neutron capture therapy a critical review  

Microsoft Academic Search

SummaryThe status of fission reactor-based neutron beams for neutron capture therapy (NCT) is reviewed critically. Epithermal neutron\\u000a beams, which are favored for treatment of deep-seated tumors, have been constructed or are under construction at a number\\u000a of reactors worldwide. Some of the most recently constructed epithermal neutron beams approach the theoretical optimum for\\u000a beam purity. Of these higher quality beams,

Otto K. Harling; Kent J. Riley

2003-01-01

117

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

118

Neutron Capture Measurements on 97Mo with the DANCE Array  

NASA Astrophysics Data System (ADS)

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

Walker, Carrie L.

119

Low Energy Accelerator-Based Neutron Sources for Neutron Capture Therapy  

Microsoft Academic Search

An epithermal neutron beam design for an accelerator -based neutron source for neutron capture therapy (NCT) has been studied. Calculation shows that, of many possible neutron-producing reactions, the Li-7(p,n)Be-7 and H-3(p,n)He -3 reactions are the more promising reactions for producing high neutron yields for NCT. The total neutron yield from the Li-7(p,n)Be-7 and H-3(p,n)He-3 reactions are 1.5 times 10^{-4} and

1992-01-01

120

Thermal Neutron Capture Cross Section of 22Ne  

NASA Astrophysics Data System (ADS)

The radiative thermal neutron capture cross section of the astrophysically important 22Ne nucleus has been measured at the guided cold neutron beam of the Budapest Research Reactor. High-pressure gas-bottles filled with mixtures of enriched 22Ne and CH4 were used. The cross section was determined by means of the comparator method, and an improved decay-scheme obtained in this work. The new value for the thermal neutron cross section is 52.7+/-0.7 mb, 18% larger than the accepted value. The influence of the new cross section on the astrophysical reaction rate is under investigation.

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

2009-01-01

121

High-resolution neutron capture and transmission measurements, and the stellar neutron-capture cross section of 88Sr  

Microsoft Academic Search

We have made new and improved measurements of the neutron capture and total cross sections for 88Sr at the Oak Ridge Electron Linear Accelerator (ORELA). Improvements over previous measurements include a wider incident neutron energy range, better resolution, the use of metallic rather than carbonate samples, better background subtraction, reduced sensitivity to sample-dependent backgrounds, and better pulse-height weighting functions. Because

P. E. Koehler; R. R. Winters; K. H. Guber; T. Rauscher; J. A. Harvey; S. Raman; R. R. Spencer; J. C. Blackmon; D. C. Larson; D. W. Bardayan; T. A. Lewis

2000-01-01

122

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

123

Use of neutron-capture plastic fibers for nondestructive assay  

SciTech Connect

Neutron-capture plastic fibers can be used as a nondestructive assay tool. The detectors consist of an active region assembled from ribbons of boron-({sup 10}B) loaded optical fibers. The mixture of the moderator and thermal neutron absorber in the fiber yields a detector with high efficiency ({var_epsilon}) and a short die-away time ({tau}). The deposited energy of the resultant charged particles is converted to light that is collected by photomultiplier tubes mounted at both ends of the fiber. Thermal neutron coincidence counters (TNCC) made of these fibers can serve to verify fissile materials generated from the nuclear fuel cycle. This type of detector may extend the range of materials now accessible to assay by {sup 3}He detectors. Experiments with single fibers of diameters 0.25, 0.50, and 1.00 mm test their ability to distinguish between the signals generated from neutron interactions and those from gamma rays. These results are compared with those obtained from simulation analyses for the same purpose. Light output and attenuation, neutron detection efficiency, and the signal-to-noise ratios of these fibers have also been investigated. The experimental results for light attenuation and neutron detection efficiency are consistent with the values obtained from simulation studies. A comparison of the performance of various configurations of the plastic scintillating fibers with that of other neutron-capture devices such as {sup 3}He detectors is also discussed.

Heger, A.S.; Grazioso, R.F.; Mayo, D.R.; Ensslin, N.; Miller, M.C.; Huang, H.Y.; Russo, P.A.

1998-12-31

124

Activation measurements of fast neutron radiative capture for 139La  

NASA Astrophysics Data System (ADS)

The neutron capture cross section of the neutron magic isotope 139La has been measured relative to that of 27Al by means of the activation method. The fast neutrons were produced via the 3H(d,n)4He reaction on Pd-300 neutron generator. The natural high-purity La2O3 powder was used as target material. Induced gamma activities were measured by a high-resolution gamma-ray spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The new values for En=13.50.2, 14.10.2, and 14.80.2 MeV are found to be 1.300.08, 1.150.08 and 0.990.07 mb, respectively. Results were discussed and compared with some corresponding values found in the literature.

Luo, Junhua; Han, Jiuning; Liu, Rong; Jiang, Li; Liu, Zhenlai; Sun, Guihua; Ge, Suhong

2013-05-01

125

Thermal-neutron capture gamma-rays. Volume 1.  

National Technical Information Service (NTIS)

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 ...

J. K. Tuli

1997-01-01

126

Thermal-neutron capture gamma-rays. Volume 2.  

National Technical Information Service (NTIS)

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 eac...

J. K. Tuli

1997-01-01

127

Proceedings of the first international symposium on neutron capture therapy  

SciTech Connect

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

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

1982-01-01

128

Computational dosimetry and treatment planning for Boron Neutron Capture Therapy  

Microsoft Academic Search

The technology for computational dosimetry and treatment planning for Boron Neutron Capture Therapy (BNCT) has advanced significantly over the past few years. Because of the more complex nature of the problem, the computational methods that work well for treatment planning in photon radiotherapy are not applicable to BNCT. The necessary methods have, however, been developed and have been successfully employed

David W. Nigg; Floyd J. Wheeler; Daniel E. Wessol; Jacek Capala; Manjeet Chadha

1997-01-01

129

Thermal-neutron capture gamma-rays. Volume 1  

Microsoft Academic Search

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 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

Tuli

1997-01-01

130

Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy  

Microsoft Academic Search

Glioblastoma multiforme and metastatic melanoma are frequent brain tumors in adults and presently still incurable diseases. Boron Neutron Capture Therapy (BNCT) is a promising alternative for this kind of pathologies. Accelerators have been proposed for BNCT as a way to circumvent the problem of siting reactors in hospitals and for their relative simplicity and lower cost among other advantages. Considerable

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

2010-01-01

131

Antiproton slowing down, capture, and decay in low-pressure helium gas  

SciTech Connect

Data on p slowing down and capture in helium at 1 and 0.2 mb at room temperature are presented and compared to the corresponding previously publicated data in molecular hydrogen and deuterium. A Monte Carlo simulation containing a low-energy extrapolation of measured p electronic stopping power in helium gas, screened Rutherford collisions, and simple cascade mechanisms is able to reproduce the gross features of the data, but cannot explain some nontrivial details of the measured distributions.

Bianconi, A.; Corradini, M.; Donzella, A.; Leali, M.; Lodi Rizzini, E.; Venturelli, L.; Zurlo, N. [Dipartimento di Chimica e Fisica per l'Ingegneria e per i Materiali, Universita di Brescia, Brescia and INFN, Gruppo di Brescia, Brescia (Italy); Bargiotti, M.; Bertin, A.; Bruschi, M.; Capponi, M.; De Castro, S.; Fabbri, L.; Faccioli, P.; Giacobbe, B.; Grimaldi, F.; Massa, I.; Piccinini, M.; Semprini Cesari, N.; Spighi, R. [Dipartimento di Fisica, Universita di Bologna and INFN, Sezione di Bologna, Bologna (Italy)] [and others

2004-09-01

132

Neutron capture by fissile and fertile actinide targets  

NASA Astrophysics Data System (ADS)

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

Maslov, Vladimir M.

2009-01-01

133

Neutron Capture Measurements on Unstable Nuclei at LANSCE  

SciTech Connect

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

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

1998-11-04

134

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

NASA Technical Reports Server (NTRS)

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

Lugmair, G. W.; Marti, K.

1972-01-01

135

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

136

Clinical considerations for neutron capture therapy of brain tumors  

SciTech Connect

The radiotherapeutic management of primary brain tumors and metastatic melanoma in brain has had disappointing clinical results for many years. Although neutron capture therapy was tried in the United States in the 1950s and 1960s, the results were not as hoped. However, with the newly developed capability to measure boron concentrations in blood and tissue both quickly and accurately, and with the advent of epithermal neutron beams obviating the need for scalp and skull reflection, it should now be possible to mount such a clinical trial of NCT again and avoid serious complications. As a prerequisite, it will be important to demonstrate the differential uptake of boron compound in brain tumor as compared with normal brain and its blood supply. If this can be done, then a trial of boron neutron capture therapy for brain tumors should be feasible. Because boronated phenylalanine has been demonstrated to be preferentially taken up by melanoma cells through the biosynthetic pathway for melanin, there is special interest in a trial of boron neutron capture therapy for metastatic melanoma in brain. Again, the use of an epithermal beam would make this a practical possibility. However, because any epithermal (or thermal) beam must contain a certain contaminating level of gamma rays, and because even a pure neutron beam causes gamma rays to be generated when it interacts with tissue, we think that it is essential to deliver treatments with an epithermal beam for boron neutron capture therapy in fractions in order to minimize the late-effects of low-LET gamma rays in the normal tissue. I look forward to the remainder of this Workshop, which will detail recent progress in the development of epithermal, as well as thermal, beams and new methods for tracking and measuring the uptake of boron in normal and tumor tissues. 10 references.

Madoc-Jones, H.; Wazer, D.E.; Zamenhof, R.G.; Harling, O.K.; Bernard, J.A. Jr. (Tufts-New England Medical Center, Boston, MA (USA))

1990-01-01

137

Experimental Determination of the Energy Released as a Result of Neutron Capture by Gadolinium  

Microsoft Academic Search

A method for performing direct measurements of the energy of the neutron-capture reaction on gadolinium is proposed and tested. Measurement of the absorbed dose is an important problem for gadolinium neutron-capture therapy.

S. A. Klykov; S. P. Kapchigashev; V. I. Potetnya; S. E. Ul'yanenko; E. S. Matusevich; Yu. A. Kurachenko

2001-01-01

138

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

139

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

140

Analytical modeling for neutron capture therapy  

SciTech Connect

The parts of the BNCT research program that involve experimental irradiations for human trials will require detailed computer modeling of the various radiation transport and interaction processes expected to occur, coupled with a display of the results in an easily interpretable form. The basic computational model will provide distributions of neutron, gamma, and charged-particle interaction rates, energy deposition rates, and statistical information that can be related to various radiobiological effects in the irradiated area. A graphics workstation that provides state-of-the-art visual computing capabilities will be employed. Capability for radiation transport and dosimetry calculations with the necessary combination of accuracy, execution speed, and display interfacing for each application will be implemented on the workstation. In addition, the workstation will be connected to the INEL CRAY XMP-24 over a high band-width (10 MHz) communications line to provide additional scientific data processing power should this be needed for some applications. Data describing the geometry, composition, and boron content of the irradiated volume for each individual experiment, or, in the case of clinical trials, each human patient will be obtained from several alternative sources. Depending on the application of interest, these will include: drawings; measurements; and other information from the experimenter or attending physician; phantom-type models and; automated transfer of medical imaging data (CT, MRI, PET) in cases where such data are available. 11 refs., 3 figs.

Wheeler, F.J.; Griebenow, M.L.; Wessol, D.E.; Nigg, D.W.

1988-01-01

141

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

142

Proposed experiment to measure ?-rays from the thermal neutron capture of gadolinium  

NASA Astrophysics Data System (ADS)

Gadolinium-157 (157Gd) has the largest thermal neutron capture cross section among any stable nuclei. The thermal neutron capture yields ?-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 ?-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.

2012-11-01

143

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

144

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 LiCO powder (93% enriched isotopic ⁶Li)

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

1996-01-01

145

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

Microsoft Academic Search

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

Floyd J. Wheeler; David W. Nigg; Jacek Capala; Peter R. D. Watkins; Corine Vroegindeweij; Iiro Auterinen; Tiina Seppl; Darren Bleuel

1999-01-01

146

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

NASA Astrophysics Data System (ADS)

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

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

147

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

148

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

Microsoft Academic Search

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

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

1999-01-01

149

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

Microsoft Academic Search

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

R. F. Martin; G. DCunha; M. Pardee; B. J. Allen

1989-01-01

150

A Monte-Carlo simulation of the capture and detection of neutrons with large liquid scintillators  

Microsoft Academic Search

The capture and detection processes of neutrons in large gadolinium ; loaded liquid scintillators have been simulated using a Monte-Carlo program. The ; capture efficiency and also the probability of detecting a captured neutron ; depend on the initial energy of the neutron. The influences of the size of the ; tank and the location of the source are studied.

J. Poitou; C. Signarbieux

1974-01-01

151

Neutron Capture Measurements at the n lowbar TOF Facility  

SciTech Connect

Nuclear astrophysics, advanced nuclear technology and nuclear structure physics present many cases that require neutron capture reaction data with high precision. In particular, refined data are needed for stellar nucleosynthesis, for nuclear waste transmutation studies, and for the design of generation IV reactors. The measurements take profit of the pulsed neutron beam of the n lowbar TOF facility at CERN, which is generated by proton-induced spallation reactions on a massive lead target. The low repetition rate of the proton beam, the high instantaneous neutron flux, and the favourable background conditions in the experimental area make this facility unique for high resolution time-of-flight measurements of neutron induced reaction cross sections. The n lowbar TOF collaboration is presently operating two different experimental set-ups. The first consists of two low-neutron sensitivity C{sub 6}D{sub 6} detectors with the analysis relying on the Pulse Height Weighting technique. In addition, a Total Absorption Calorimeter, consisting of 40 BaF{sub 2} crystals covering the whole solid angle, was used. A review of several capture measurements with these detectors on selected stable and unstable samples will be presented.

Milazzo, P. M.; Abbondanno, U.; Fujii, K. [Istituto Nazionale di Fisica Nucleare, Trieste (Italy); Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W.; Ferrant, L.; Gunsing, F.; Pancin, J.; Perrot, L.; Plukis, A.; Stephan, C.; Tassan-Got, L. [Centre National de la Recherche Scientifique/IN2P3-IPN, Orsay (France); Alvarez, H.; Duran, I.; Paradela, C. [Universidade de Santiago de Compostela (Spain); Alvarez-Velarde, F.; Cano-Ott, D.; Embid-Segura, M. [Centro de Investigaciones Energeticas Medioambientales y Technologicas, Madrid (Spain)] (and others)

2009-03-31

152

In situ neutron capture spectroscopy of geological formations  

NASA Astrophysics Data System (ADS)

Neutron-capture-induced gamma-ray spectroscopy has been useful for determining the geological properties of porosity, lithology, and water salinity of the rock and fluid outside the iron casing which is cemented into most oil wells. This paper discusses such measurements using a pulsed source of 14-MeV neutrons and a NaI(T1) gamma-ray detector. The most difficult task in interpreting these measurements is to separate signals generated by elements in the formation rock and fluid from those due to elements inside the well bore. The physical properties at work here include fast-neutron thermalization times, thermal-neutron diffusion, competing neutron-capture cross sections, and gamma-ray transport to the detector. Results from studying the geophysical parameters which most affect these physical properties, porosity and water salinity, are presented here. Methods for enhancing the spectral contribution from the earth formation relative to that from the borehole are discussed. These include understanding the time dependence of the spectral shape, optimizing the source-to-detector spacing, and employing absorptive borehole fluid displacers.

Grau, J. A.; Antkiw, S.; Hertzog, R. C.; Marente, R. A.; Schweitzer, J. S.

1985-01-01

153

Neutron radiative capture methods for surface elemental analysis  

USGS Publications Warehouse

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

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

1970-01-01

154

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

155

100CHANNEL TIME-OF-FLIGHT ANALYZER FOR A SLOW-NEUTRON MECHANICAL CHOPPER  

Microsoft Academic Search

Construction of the 100-channel analyzer is described. The analyzer ; yields a spectrum of neutron counts versus time-of-flight between a slow neutron ; chopper and neutron detectors. The detectors are placed some fixed distance ; (flight path) away from the mechanical chopper. The 100-channel analyzer must ; receive a \\

Sawicki

1959-01-01

156

A fundamental study on hyper-thermal neutrons for neutron capture therapy.  

PubMed

The utilization of hyper-thermal neutrons, which have an energy spectrum with a Maxwellian distribution at a higher temperature than room temperature (300 K), was studied in order to improve the thermal neutron flux distribution at depth in a living body for neutron capture therapy. Simulation calculations were carried out using a Monte Carlo code 'MCNP-V3' in order to investigate the characteristics of hyper-thermal neutrons, i.e. (i) depth dependence of the neutron energy spectrum, and (ii) depth distribution of the reaction rate in a water phantom for materials with 1/v neutron absorption. It is confirmed that hyper-thermal neutron irradiation can improve the thermal neutron flux distribution in the deeper areas in a living body compared with thermal neutron irradiation. When hyper-thermal neutrons with a 3000 K Maxwellian distribution are incident on a body, the reaction rates of 1/v materials such as 14N, 10B etc are about twice that observed for incident thermal neutrons at 300 K, at a depth of 5 cm. The limit of the treatable depth for tumours having 30 ppm 10B is expected to be about 1.5 cm greater by utilizing hyper-thermal neutrons at 3000 K compared with the incidence of thermal neutrons at 300 K. PMID:15551549

Sakurai, Y; Kobayashi, T; Kanda, K

1994-12-01

157

Neutron-capture Nucleosynthesis in the First Stars  

NASA Astrophysics Data System (ADS)

Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have observed 16 stars with enhanced carbon or nitrogen using the MIKE Spectrograph on the Magellan Telescopes at Las Campanas Observatory and the Tull Spectrograph on the Smith Telescope at McDonald Observatory. We present radial velocities, stellar parameters, and detailed abundance patterns for these stars. Strontium, yttrium, zirconium, barium, europium, ytterbium, and other heavy elements are detected. In four stars, these heavy elements appear to have originated in some form of r-process nucleosynthesis. In one star, a partial s-process origin is possible. The origin of the heavy elements in the rest of the sample cannot be determined unambiguously. The presence of elements heavier than the iron group offers further evidence that zero-metallicity rapidly rotating massive stars and pair instability supernovae did not contribute substantial amounts of neutron-capture elements to the regions where the stars in our sample formed. If the carbon- or nitrogen-enhanced metal-poor stars with low levels of neutron-capture elements were enriched by products of zero-metallicity supernovae only, then the presence of these heavy elements indicates that at least one form of neutron-capture reaction operated in some of the first stars. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile, and The McDonald Observatory of The University of Texas at Austin.

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

2014-04-01

158

Advances in Atomic Data for Neutron-Capture Elements  

Microsoft Academic Search

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

N. C. Sterling; M. C. Witthoeft; D. A. Esteves; P. C. Stancil; A. L. D. Kilcoyne; R. C. Bilodeau; A. Aguilar

2011-01-01

159

gamma Rays Following Thermal Neutron Capture in Titanium  

Microsoft Academic Search

The gamma rays following thermal neutron capture in titanium have been studied with two high resolution spectrometers and with an angular correlation arrangement using two sodium iodide scintillation spectrometers. The high resolution instruments were a pair spectrometer for the energy range 2.8 to 11.0 Mev and a double flat crystal diffraction spectrometer for the energy range 0.14 to 5 Mev.

J. W. Knowles; G. Manning; G. A. Bartholomew; P. J. Campion

1959-01-01

160

Neutron-capture processes in the early Galaxy  

Microsoft Academic Search

Many observational studies of metal-poor stars that exhibit large excesses of r-process elements have been made in the past decade, and have provided useful constraints on modeling this pro- cess. Recent abundance studies have revealed the existence of extremely metal-poor stars that have large enhancements exclusively of the light neutron-capture elements, indicating that a nu- cleosynthesis process that efficiently yields

Wako Aoki

2006-01-01

161

Analytical applications of neutron capture gamma-ray spectroscopy  

Microsoft Academic Search

Prompt gamma rays from thermally induced nuclear reactions have been used to estimate the boron, chlorine and phosphorus contents in industrial and reference materials. A neutron capture gamma-ray spectroscopy facility for analytical purposes using 252Cf sources has been designed and calibrated and is described in this paper. The facility is principally designed for measurement of the prompt gamma-ray spectra obtained

A. M. Hassan; E. Gantner; E. Mainka; H. Ruf; U. Kuhnes; M. Mostafa

1983-01-01

162

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

163

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

164

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

165

Levels of 159Gd populated in average resonance neutron capture  

NASA Astrophysics Data System (ADS)

The primary ?-rays and energy levels in 159Gd were investigated in average resonance neutron capture using tailored neutron beams at 2 keV and 24 keV and a pair spectrometer at the high flux reactor at Brookhaven. Nearly 200 levels with spin up to {5}/{2} are reported below 3 MeV. The distribution of radiative strength in this nucleus was obtained and is compared with a giant dipole resonance and single-particle strength models. The density of observed levels was determined and is described in terms of the constant temperature Fermi gas model. The neutron binding energy in 159Gd was determined to be 5943.32(12) keV.

Granja, C.; Pospil, S.; Telezhnikov, S. A.; Chrien, R. E.

2003-12-01

166

Improved neutron capture cross section of Pu239  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

167

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

1989-01-01

168

Gadolinium neutron capture therapy for brain tumors: a computer study.  

PubMed

A Monte Carlo computer study of the total dose distribution from neutrons and prompt gamma emissions (but excluding the contribution from conversion and Auger electrons) for gadolinium neutron capture therapy of brain tumors has been carried out in order to test the theoretic feasibility of this modality using commercially available magnetic resonance contrast media. The three-dimensional dose distribution calculations were performed in a spherical head phantom with a spherical tumor at the center. Potentially achievable gadolinium concentrations of 150 micrograms/g of tissue in tumor and 3 micrograms/g in normal tissue were assumed with enrichment to 79.9% gadolinium-157, as supplied by Oak Ridge National Laboratory. Irradiation was assumed to be with a 2-keV monoenergetic cylindrical epithermal neutron beam having a radius of 4 cm. The three-dimensional thermal neutron fluence resulting from the 2-keV beam propagation through the tissue was modeled. For a single neutron beam, the maximum dose is delivered within the tumor but the dose is very inhomogeneous across the tumor volume due to rapid decrease of thermal neutron fluence with depth. Two parallel opposed neutron beams deliver to the interface of normal and malignant tissue 70%-80% of the maximum dose received at the center of the tumor. To deliver an average tumor dose of 500 cGy in 10 min would require a 2-keV source neutrons number of 8.0 x 10(11) per s within the geometry of the beam. PMID:1435610

Masiakowski, J T; Horton, J L; Peters, L J

1992-01-01

169

Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments  

NASA Astrophysics Data System (ADS)

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

2005-05-01

170

Transport calculations of depth-dose distributions for gadolinium neutron capture therapy  

Microsoft Academic Search

Depth-dose distributions were calculated for thermal and epithermal neutron fluence and capture gamma ray dose rates using a two-dimensional neutron-coupled gamma-ray transport code (DOT 3.5) for gadolinium neutron capture therapy. The results show that (i) a capture gamma-ray dose rate of 10 Gy h-1 was obtained with a thermal neutron fluence rate of 1.5*109 cm-2 s-1 in a simulated tumour

T. Matsumoto

1992-01-01

171

Low-lying positive parity states in 195Ir following double neutron capture  

Microsoft Academic Search

Multiple neutron capture reactions have been studied on 193Ir targets and gamma and electron spectroscopy performed. Double neutron capture events were separated from all others and a level scheme of 195Ir deduced. Gamma-ray energies and multipolarities are tabulated. A neutron capture cross-section for the reaction 194Ir(n, gamma) of 1500+\\/-290b has been determined and the neutron binding energy of 195Ir measured

G. G. Colvin; H. G. Brner; P. Geltenbort; F. Hoyler; S. A. Kerr; K. Schreckenbach; J. A. Cizewski

1987-01-01

172

Biological efficacy of a boronated imidocaptate for neutron capture  

SciTech Connect

Neutron capture therapy (NCT) is a binary system that utilizes intracellular {sup 10}B as a target atom for subsequent activation by thermal neutrons according to the {sup 10}B(n,{alpha}){sup 7}Li reaction. In the 1950s, clinical trials of NCT for the treatment of malignant brain tumors were unsuccessful because of (a) the poor penetration of the thermal neutrons and (b) the lack of boron compounds that would give high tumor-to-normal-tissue ratios. The recent development of epithermal neutron beams should permit greater neutron penetration to the depth of the tumor. Additionally, second- and third-generation boron compounds have been synthesized. Many of these are being investigated for their potential use in NCT. Among these are nitroimidazoles. Nitroimidazoles have been of interest as photon radiation sensitizers and have the characteristics of facile tumor penetration and susceptibility to nitroreduction in the tumor. This latter characteristic yields metabolites that bind to cellular macromolecules. Such binding may interfere with DNA repair, and this may be a mechanism in the synergizing activity of the nitroimidazole for alkylating agents or hyperthermia. The DNA repair inhibition, in addition to oxygen enhancement, may play a role in the observed ability of nitroimidazoles to synergize the photon therapy of tumors. The authors took advantage of these features to use this class of compounds as a carrier of boron for NCT.

Laster, B.H.; Fairchild, R.G. (Brookhaven National Lab., Upton, NY (United States)); Swenson, D. (Karkinos Biochem, Inc., Chandler, AZ (United States)); Metzger, R.

1991-01-01

173

Modification of the Resonance Treatment in Multigroup Neutron Slowing-down Codes.  

National Technical Information Service (NTIS)

The previously reported computer codes GRACE and BETTY for resonance treatment in the multigroup neutron slowing-down processes have been improved, employing the new results of resonance absorption calculations. The total resonance integral formulae were ...

J. Gado

1978-01-01

174

Prompt response self-powered neutron detectors. 1: The effective charge per neutron captured  

Microsoft Academic Search

A simple, physically transparent method is developed to calculate the electric charge per neutron captured in prompt response self-powered neutron detectors (SPNDs), which contributes to the emitter-collector current. This charge is written as the energy integral of the product of two functions: the spectral function S(E), which is the energy spectrum of all electrons resulting from prompt gamma interactions with

M. D. C. Lopes; J. M. Avila

1987-01-01

175

Neutron Capture Cross Sections for the Re/Os Clock  

SciTech Connect

The radioactive decay of 187Re {yields} 187Os (t1/2 = 43 Gyr) is suited for dating the onset of heavy-element nucleosynthesis. The radiogenic contribution to the 187Os abundance is the difference between the natural abundance and the corresponding s-process component. This component can be obtained via the well-established {sigma}N systematics using the neighboring s-only isotope 186Os, provided the neutron-capture cross sections of both isotopes are known with sufficient accuracy. We report on a new set of experiments performed with a C6D6 detector array at the n{sub T}OF neutron spallation facility of CERN. The capture cross sections of 186Os, 187Os, and 188Os have been measured in the neutron-energy range between 1 eV and 1 MeV, and Maxwellian-averaged cross sections were deduced for the relevant thermal energies from kT=5 keV to 100 keV.

Mosconi, M.; Heil, M.; Kaeppeler, F.; Plag, R.; Voss, F.; Wisshak, K. [Forschungszentrum Karlsruhe GmbH (FZK), Institut fuer Kernphysik (Germany); Mengoni, A.; Cennini, P.; Chiaveri, E.; Ferrari, A.; Fitzpatrick, L.; Herrera-Martinez, A.; Kadi, Y.; Sarchiapone, L.; Vlachoudis, V.; Wendler, H. [CERN, Geneva (Switzerland); Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W. [EA/Saclay - DSM, Gif-sur-Yvette (France)] [and others

2005-05-24

176

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

177

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

178

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

Microsoft Academic Search

Parameter studies, design calculations and initial neutronic performance measurements have been completed for a new thermal neutron beamline to be used for neutron capture therapy cell and small-animal radiobiology studies at the University of Missouri Research Reactor. The beamline features the use of single-crystal silicon and bismuth sections for neutron filtering and for reduction of incident gamma radiation. The computational

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

2010-01-01

179

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

180

Stellar neutron capture rates and the s process  

NASA Astrophysics Data System (ADS)

Neutron reactions are responsible for the formation of the elements heavier than iron. The corresponding scenarios relate to helium burning in Red Giant stars (s process) and to supernova explosions (r and p processes). The s process, which operates in or near the valley of ?-stability, has produced about half of the elemental abundances between Fe and Bi. Accurate (n, ?) cross sections are the essential input for s process studies, because they determine the abundances produced by that process. Following a brief summary of the neutron capture processes, the focus will be set on the s process in massive stars, where the role of reliable cross section information is particularly important. Eventually, the intriguing aspects of the origin of 60Fe will be addressed. Attempts to determine the stellar cross section of that isotope are pushing experimental possibilities to their limits and present a pertinent challenge for future facilities.

Kppeler, F.

2012-02-01

181

Two-neutron capture reactions in supernovae neutrino bubbles  

NASA Astrophysics Data System (ADS)

Recent calculations suggest that the neutrino heated bubbles in the postcollapse phase of type II supernovae may be the site of the r process. The nucleosynthesis process depends on the expansion and cooling rates as well as on the rates of the ?-particle and neutron recombination processes that bridge the mass gaps at A = 5 and 8. We have reexamined the rate for the important reaction 4He(?n,?)9Be, and estimated the rates for the two neutron capture reactions on 6He and 8He which could provide an alternative reaction path. We find that the most important reaction for initiating the ? process is the 4He(?n,?)9Be reaction, as suggested by earlier work.

Grres, J.; Herndl, H.; Thompson, I. J.; Wiescher, M.

1995-10-01

182

Towards epithermal Boron Neutron Capture Therapy for cancer  

SciTech Connect

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

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

1994-12-31

183

Neutron capture records of mesosiderites and an iron meteorite  

NASA Astrophysics Data System (ADS)

The Sm and Gd isotopic compositions of silicates from six mesosiderites (Dalgaranga, Estherville, Morristown, Northwest Africa (NWA) 1242, NWA 2932, and Vaca Muerta) and one iron meteorite (Udei Station) were determined to elucidate the cosmic-ray exposure records. All seven samples showed significant 150Sm/ 149Sm and 158Gd/ 157Gd isotopic shifts from neutron capture reactions corresponding to neutron fluences of (1.3-21.8) 10 15 n cm -2. In particular, Vaca Muerta showed a significantly higher neutron fluences than the other six samples. The parameter for the degree of neutron thermalization ( ?Sm/ ?Gd) also showed a significant difference between Vaca Muerta (0.76) and the other samples (0.93-1.20). These results suggest a two-stage irradiation of the Vaca Muerta silicates in the parent body (>50 Ma) before formation of the mesosiderite and during its transit to Earth (138 Ma). This is consistent with the 81Kr-Kr cosmic-ray exposure age data of a Vaca Muerta pebble from a previous noble gas isotopic study.

Hidaka, Hiroshi; Yoneda, Shigekazu

2011-10-01

184

Systematic Pseudomagnetic Measurements of the Spin-Dependent Scattering Length of Slow Neutrons with Atomic Nuclei  

NASA Astrophysics Data System (ADS)

The magnitude and the sign of spin-dependent scattering lengths of slow neutrons by nuclei of Li7, Al27, Sc45, Zr91, Nb93, La139, and Ta181 have been determined by measuring the dependence of the precession angle of the neutron spins on the nuclear polarization of the scattering target.

Roubeau, P.; Abragam, A.; Bacchella, G. L.; Glttli, H.; Malinovski, A.; Meriel, P.; Piesvaux, J.; Pinot, M.

1974-07-01

185

Analytical calculations of neutron slowing down and transport in the constant-cross-section problem  

Microsoft Academic Search

Aspects of the problem of neutron slowing down and transport in an infinite medium consisting of a single nuclide that scatters elastically and isotropically and has energy-independent cross sections were investigated. The method of singular eigenfunctions was applied to the Boltzmann Equation governing the Laplace transform (with respect to the lethargy variable) of the neutron flux. A new sufficient condition

Cacuci

1978-01-01

186

Neutron slowing down and transport in a medium of constant cross section. I. Spatial moments  

Microsoft Academic Search

Some aspects of the problem of neutron slowing down and transport have been investigated in an infinite medium consisting of a single nuclide scattering elastically and isotropically without absorption and with energy-independent cross sections. The method of singular eigenfunctions has been applied to the Boltzmann equation governing the Laplace transform (with respect to the lethargy variable) of the neutron flux.

Dan G. Cacuci; Herbert Goldstein

1977-01-01

187

Design of a boron neutron capture enhanced fast neutron therapy assembly  

NASA Astrophysics Data System (ADS)

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 multiforme (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 cm2 treatment beam. The calculated boron dose enhancement at 5.7-cm depth in a water-filled head phantom in the assembly with a 5x5 cm2 collimation was 21.9% per 100-ppm 10B 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 cm2 fast neutron treatment beam. To validate the design calculations, a simplified BNCEFNT assembly was built using four lead bricks to form a 5x5 cm2 collimator. Five 1.0-cm thick 20x20 cm2 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 10B) 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 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

188

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

SciTech Connect

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

Sleaford, B

2007-10-29

189

Boron neutron capture therapy for malignant melanoma: An experimental approach  

SciTech Connect

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

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

1989-07-01

190

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

191

Transport calculations of depth-dose distributions for gadolinium neutron capture therapy.  

PubMed

Depth-dose distributions were calculated for thermal and epithermal neutron fluence and capture gamma ray dose rates using a two-dimensional neutron-coupled gamma-ray transport code (DOT 3.5) for gadolinium neutron capture therapy. The results show that (i) a capture gamma-ray dose rate of 10 Gy h-1 was obtained with a thermal neutron fluence rate of 1.5 x 10(9) cm-2 s-1 in a simulated tumour containing 5000 PPM gadolinium placed near the surface of a water phantom, (ii) deep-seated tumours may be treated with epithermal neutrons, and (iii) gadolinium neutron capture therapy appears to achieve comparable dose distributions to those of boron neutron capture therapy. PMID:1741420

Matsumoto, T

1992-01-01

192

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

SciTech Connect

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

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

1991-04-01

193

High-energy gamma rays of 76As following thermal and epithermal neutron capture  

Microsoft Academic Search

Using a Ge(Li) detector, the energies and intensities of the high-energy gamma transitions of the reaction 75As(n, gamma)76As have been measured. By comparison between gamma-ray intensities in thermal and epithermal neutron capture, 6 intense transitions are found to be due mainly to direct neutron capture. A classification of gamma-ray intensities after epithermal neutron capture indicated an E1 multipolarity for 8

P. Gryksa; P. Riehs; K. Rumpold

1969-01-01

194

Neutron capture effects on samarium, europium, and gadolinium in Apollo 15 deep drill-core samples  

Microsoft Academic Search

The isotopic compositions of Sm and Gd in seven lunar samples from the Apollo 15 deep drill core were determined to discuss the effects of neutron capture near the lunar surface. Large isotopic deviations of 150Sm\\/149Sm, 156Gd\\/155Gd and 158Gd\\/157Gd derived from neutron capture effects were observed in all samples. Although neutron capture products in lunar samples were extensively in the

Hiroshi Hidaka; Mitsuru Ebihara; Shigekazu Yoneda

2000-01-01

195

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

DOEpatents

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

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

1999-05-11

196

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

197

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

198

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

National Technical Information Service (NTIS)

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...

D. D. Joel R. Bergland J. Capala

1995-01-01

199

Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

200

Computational dosimetry and treatment planning considerations for neutron capture therapy.  

PubMed

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. PMID:12749704

Nigg, David W

2003-01-01

201

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

202

Hydrocarbon scale deposits measurements by neutron moderation and capture gamma methods  

Microsoft Academic Search

Nuclear techniques have been used for the detection of hydrocarbon deposits found inside the pipes in oil refinery and chemical plants. Such detection is usually very difficult. The techniques used here were: neutron moderation and capture gamma rays. In the first method, neutrons from 241Am?Be neutron source interact with the scale inside the pipe. Fast neutrons penetrate the pipe wall

Samir Abdul-Majid; Abdulghani Melaibari; Basim Malki

1996-01-01

203

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

204

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

205

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

SciTech Connect

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

Harasawa, S. (Rikkyo Univ., Nagasaka, Japan); Nakamoto, A.; Hayakawa, Y.; Egawa, J.

1981-10-01

206

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

207

Design of neutron beams for neutron capture therapy using a 300kW slab TRIGA reactor  

Microsoft Academic Search

A design for a slab reactor to produce an epithermal neutron beam and a thermal neutron beam for use in neutron capture therapy (NCT) is described. A thin reactor with two large-area faces, a ``slab`` reactor, was planned using eighty-six 20% enriched TRIGA fuel elements and four BC control rods. Two neutron beams were designed: an epithermal neutron beam from

1995-01-01

208

Cross sections and ?-rays from multiple neutron capture in151Eu  

NASA Astrophysics Data System (ADS)

Primary capture gamma rays following multiple neutron capture in151Eu have been measured as a function of the irradiation time. Neutron capture cross sections of the152Eu 3- groundstate and of the152Eu 0- isomer ( T 1/2=9.3h) were determined. These cross sections are relevant for the interpretation of inelastic scattering of neutrons at isomeric states with energy gain (neutron acceleration). The level scheme of153Eu has been extended. Neutron binding energies of152Eu,153Eu,153Gd and154Gd are given.

von Egidy, T.; Brner, H. G.; Hoyler, F.

1985-12-01

209

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.

210

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

211

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

212

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

213

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

214

Neutron Capture and Fission Measurements on Actinides at Dance  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

215

Scissors mode of Gd nuclei studied from resonance neutron capture  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

216

High-resolution neutron capture and transmission measurements for 116,120Sn, and their stellar neutron-capture cross sections at s-process temperatures  

Microsoft Academic Search

We have made high-resolution measurements of the neutron capture and total cross sections for 116Sn and the neutron capture cross section for 120Sn from 50 eV to 500 keV at the Oak Ridge Electron Linear Accelerator (ORELA). There have been no previously reported high-resolution measurements of these cross sections in this energy range. We performed an R-matrix analysis of our

P. E. Koehler; J. A. Harvey; R. R. Winters; K. H. Guber; R. R. Spencer

2001-01-01

217

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

2012-10-26

218

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

219

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

Microsoft Academic Search

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

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

2008-01-01

220

Improved neutron capture data and evaluation with statistical nuclear structure models for transport libraries  

Microsoft Academic Search

My goal in this work was to improve the nuclear data libraries used for transport calculations with respect to the neutron capture reaction. I have taken a new experimental database of discrete gamma spectra from neutron capture and coupled this with a statistical nuclear structure code not used for this purpose before to account for the unresolved gamma ray quasi-continuum

Bradley William Sleaford

2007-01-01

221

Investigation of the tungsten isotopes via thermal neutron capture  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

222

Evidence for valence neutron capture in S-wave neutron capture in ³⁶Ar and ⁵⁴Fe  

Microsoft Academic Search

The valence and channel neutron model of Lane and Lynn remarkably account for partial radiative widths of neutron resonances in the 3p-giant resonance. In this investigation, evidence is presented for valence neutron capture at and in the neighborhood of the 3s-giant resonance in target nuclei Ar-36 and Fe-54. In addition, the variation of the correlation coefficient rho(GAMMA\\/sub ..gamma..ij\\/ E\\/sub ..gamma..\\/\\/sub

Mughabghab

1975-01-01

223

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

224

Thermal-Neutron-Capture Gamma Rays in Yb170, Yb172, and Yb174  

Microsoft Academic Search

A Ge(Li) detector was used to investigate the gamma spectra following thermal neutron capture in enriched isotope targets of Yb170, Yb172, and Yb174. In addition to capture in these isotopes, gamma lines were identified as resulting from thermal capture in Yb171 and Yb173. The neutron separation energies of Yb171, Yb172, Yb173, Yb174, and Yb175 were found to be 6616, 8023,

A. I. Namenson; J. C. Ritter

1969-01-01

225

Neutron-Capture Gamma-Rays of Bromine, Copper, Iridium, Nickel and Tungsten  

Microsoft Academic Search

Investigations were undertaken to obtain information about the formation ; and decay of nuclei occurring as the products in neutron-capture reactions. ; Samples of natural bromine, copper, iridium, nickel, and tungsten, and separated ; isotope, samples of Br⁷⁹, Br⁸¹, Ni⁵⁸, Ni⁶° , Ni\\/sup ; 62\\/, W¹⁸², W¹⁸⁴, and W¹⁸⁶, were placed in a neutron beam and ; their neutron-capture gamma-ray

Paul Albert Treado

1962-01-01

226

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

227

Measuring of gamma-ray energy due to thermal neutron capture of copper and nickel  

Microsoft Academic Search

A source of fast neutrons is pulsed to irradiate the formations surrounding a borehole with neutrons to produce gamma-rays from thermal neutron capture of the metallic materials located within the formations. Such gamma-rays are detected as an indication of the presence of such materials within the formations.

Givens

1983-01-01

228

Measurements of fast neutron capture cross sections on 63 Cu and 186 W  

Microsoft Academic Search

Neutron capture cross sections on 63Cu and 186W were measured by fast neutron activation method at neutron energies from 1 to 2 MeV. Monoenergetic fast neutrons were produced\\u000a by 3H(p,n)3He reaction. Neutron energy spread by target thickness, which was assumed to be the main factor of neutron energy spread,\\u000a was estimated to be 1.5% at neutron energy of 2.077 MeV.

G. D. Kim; H. J. Woo; H. W. Choi; N. B. Kim; T. K. Yang; J. H. Chang; K. S. Park

2007-01-01

229

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; Seppl, T; Bleuel, D

1999-07-01

230

MCNP speed advances for boron neutron capture therapy  

SciTech Connect

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

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

1998-04-01

231

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

232

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

SciTech Connect

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

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

2013-07-01

233

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

234

Determining neutron capture cross sections via the surrogate reaction technique  

SciTech Connect

Indirect methods play an important role in the determination of nuclear reaction cross sections that are hard to measure directly. In this paper we investigate the feasibility of using the so-called surrogate method to extract neutron capture cross sections for low-energy compound-nuclear reactions in spherical and near-spherical nuclei. We present the surrogate method and develop a statistical nuclear reaction simulation to explore different approaches to utilizing surrogate reaction data. We assess the success of each approach by comparing the extracted cross sections with a predetermined benchmark. In particular, we employ regional systematics of nuclear properties in the 34{<=}Z{<=}46 region to calculate (n,{gamma}) cross sections for a series of Zr isotopes and to simulate a surrogate experiment and the extraction of the desired cross section. We identify one particular approach that may provide very useful estimates of the cross section, and we discuss some of the limitations of the method. General recommendations for future (surrogate) experiments are also given.

Forssen, C. [Fundamental Physics, Chalmers University of Technology, SE-41296 Goeteborg (Sweden); Lawrence Livermore National Laboratory, P.O. Box 808, L-414, Livermore, California 94551 (United States); Dietrich, F. S.; Escher, J.; Hoffman, R. D.; Kelley, K. [Lawrence Livermore National Laboratory, P.O. Box 808, L-414, Livermore, California 94551 (United States)

2007-05-15

235

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

Microsoft Academic Search

The neutron capture cross sections of 147,148,149,150,152Sm were measured in the energy range from 3 to 225 keV at the Karlsruhe Van de Graaff accelerator using gold as a standard. 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 4pi barium fluoride detector. Several runs

K. Wisshak; K. Guber; F. Voss; F. Kppeler; G. Reffo

1993-01-01

236

Neutron capture in [sup 148,150]Sm: A sensitive probe of the [ital s]-process neutron density  

Microsoft Academic Search

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. Neutrons were produced via the [sup 7]Li([ital p],[ital n])[sup 7]Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4[pi

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

1993-01-01

237

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

PubMed

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

Shih, J L; Brugger, R M

1992-01-01

238

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

NASA Astrophysics Data System (ADS)

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

Bosko, Andrey

239

A coupled deterministic\\/stochastic method for computing neutron capture therapy dose rates  

Microsoft Academic Search

Neutron capture therapy (NCT) is an experimental method of treating brain tumors and other cancers by: (1) injecting or infusing the patient with a tumor-seeking, neutron target-labeled drug; and (2) irradiating the patient in an intense epithermal neutron fluence. The nuclear reaction between the neutrons and the target nuclei (e.g. sp{10}B(n,alpha)sp7Lirbrack releases energy in the form of high-LET (i.e. energy

Thomas Richard Hubbard

1997-01-01

240

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

241

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

242

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

PubMed

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(max)/phi(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(max)/phi(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. PMID:18196797

Bortolussi, S; Altieri, S

2007-12-01

243

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

NASA Astrophysics Data System (ADS)

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

Ullmann, J. L.

2014-09-01

244

Neutron Capture and Neutron Total Cross Sections Measurements for {sup 27}Al at the Oak Ridge Electron Linear Accelerator  

SciTech Connect

We have used the Oak Ridge Electron Linear Accelerator (ORELA) to measure neutron total and capture cross sections of {sup 27}Al in the energy range from 100 eV to {approximately}400 keV. We report the resonance parameters as well as the Maxwellian average capture cross sections.

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

1999-08-30

245

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

Microsoft Academic Search

At Kyoto University Research Reactor Institute (KURRI), 275 clinical trials of boron neutron capture therapy (BNCT) have been performed as of March 2006, and the effectiveness of BNCT has been revealed. In order to further develop BNCT, it is desirable to supply accelerator-based epithermal-neutron sources that can be installed near the hospital. We proposed the method of filtering and moderating

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

2009-01-01

246

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

NASA Astrophysics Data System (ADS)

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

Barnes, David Daniel

247

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.; Kppeler, F. (Franz); Chamberlin, E. P. (Edwin P.)

2002-01-01

248

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

NASA Astrophysics Data System (ADS)

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

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

1999-11-01

249

(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

250

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

DOEpatents

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

Gabel, D.

1991-06-04

251

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

DOEpatents

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

Gabel, D.

1992-09-01

252

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

253

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

National Technical Information Service (NTIS)

Boronated thioureas have been proposed for neutron capture therapy, but no boronated analog has been reported in the literature. The major difficulty in synthesizing such derivatives lies in the properties of the dihydroxylboryl group, which is easily cle...

D. Gabel

1989-01-01

254

Comparison of analytical transport and stochastic solutions for neutron slowing down in an infinite medium  

SciTech Connect

A comparison of the numerical solutions of the transport equation describing the steady neutron slowing down in an infinite medium with constant cross sections is made with stochastic solutions obtained from tracking successive neutron histories in the same medium. The transport equation solution is obtained using a numerical Laplace transform inversion algorithm. The basis for the algorithm is an evaluation of the Bromwich integral without analytical continuation. Neither the transport nor the stochastic solution is limited in the number of scattering species allowed. The medium may contain an absorption component as well.

Jahshan, S.N.; Wemple, C.A. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Ganapol, B.D. [Arizona Univ., Tucson, AZ (United States)

1993-04-01

255

Comparison of analytical transport and stochastic solutions for neutron slowing down in an infinite medium  

SciTech Connect

A comparison of the numerical solutions of the transport equation describing the steady neutron slowing down in an infinite medium with constant cross sections is made with stochastic solutions obtained from tracking successive neutron histories in the same medium. The transport equation solution is obtained using a numerical Laplace transform inversion algorithm. The basis for the algorithm is an evaluation of the Bromwich integral without analytical continuation. Neither the transport nor the stochastic solution is limited in the number of scattering species allowed. The medium may contain an absorption component as well.

Jahshan, S.N.; Wemple, C.A. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Ganapol, B.D. (Arizona Univ., Tucson, AZ (United States))

1993-01-01

256

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

2013-06-01

257

Low-energy level structure of 151Sm by neutron capture reactions and theoretical interpretation  

Microsoft Academic Search

A nuclear structure study of 151Sm is presented on the basis of low-energy gamma-ray and conversion electron spectroscopy, in connection with thermal neutron capture, and high-energy primary gamma-ray measurements following average resonance neutron capture. The level scheme is established up to 1020 keV and incorporates 44 levels. Unique spin and parity assignments are made for 34 levels, and narrow limits

G. Vandenput; P. H. M. van Assche; L. Jacobs; J. M. van den Cruyce; R. K. Smither; K. Schreckenbach; T. von Egidy; D. Breitig; H. A. Baader; H. R. Koch

1986-01-01

258

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

NASA Astrophysics Data System (ADS)

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

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

259

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

260

Further Study of Nuclear Resonant Scattering Using Neutron-Capture Gamma Rays  

Microsoft Academic Search

The study of resonance scattering of neutron-capture gamma rays has been extended using 22 capture gamma sources and 57 scattering targets. About 50 resonance-scattering events have been observed in 23 elements and the effective cross sections evaluated. Some cases of complex spectra are described. The association of the scattering with nuclei in the region of closed shells is clearly shown.

G. Ben-David; B. Arad; J. Balderman; Y. Schlesinger

1966-01-01

261

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

Microsoft Academic Search

Pulsed neutron capture (PNC) technique have played an important role in determining steam saturation, a key component to estimating residual oil volume in steamfloods. While experience using PNC tools has been good, recent results from three-dimensional neutron transport simulation suggest a critical failing in the prevailing techniques. At steam saturation above 50--70 saturation units, the leading parameter ceases to be

David Daniel Barnes

2008-01-01

262

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

263

Neutron capture cross sections near 30 keV using a Moxon-Rae detector  

Microsoft Academic Search

Neutron radiative capture cross sections were measured using a Moxon-Rae ; detector, for neutrons near 30 kev. A time-of-flight system with less than 3 ns ; resolution and a 7 cm flight path was shown applicable to small sample ; measurements. Cross sections at 30 kev for Mo, Cd, Sn, Ta, W, Pt, and Au and ; cross sections versus

R. L. Macklin; J. H. Gibbons; T. Inada

1963-01-01

264

AVERAGE RADIATIVE CAPTURE CROSS SECTIONS FOR 30- AND 65-kev NEUTRONS  

Microsoft Academic Search

Neutron radiative capture cross sections near 30 and 65 kev have been ; measured for a large number of elements by means of a large liquid scintillator ; and a pulsed neutron source. The results show definitive even vs odd A effects ; as well as systematic variations due primarily to effects of nuclear shells. ; Calculations of the scintillator

R. L. Macklin; J. H. Gibbons; T. Inada

1963-01-01

265

Dynamic infrared imaging for biological and medical applications in Boron neutron capture therapy  

Microsoft Academic Search

Boron Neutron Capture Therapy (BNCT) is a treatment modality, currently focused on the treatment of cancer, which involves a tumor selective 10B compound and a specially tuned neutron beam to produce a lethal nuclear reaction. BNCT kills target cells with microscopic selectivity while sparing normal tissues from potentially lethal doses of radiation. In the context of the Argentine clinical and

Gustavo A. Santa Cruz; Sara J. Gonzlez; Alejandra Dagrosa; Amanda E. Schwint; Marina Carpano; Vernica A. Trivillin; Esteban F. Boggio; Jos Bertotti; Julio Marn; Andrea Monti Hughes; Ana J. Molinari; Miguel Albero

2011-01-01

266

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

PubMed

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

Tanaka, Kenichi; Endo, Satoru; Hoshi, Masaharu

2010-01-01

267

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

PubMed

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

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

2000-01-01

268

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

269

Neutron-Capture Elements in the Very Metal-poor Star HD 88609: Another Star with Excesses of Light Neutron-Capture Elements  

NASA Astrophysics Data System (ADS)

We obtained a high-resolution, high-signal-to-noise UV-blue spectrum of the extremely metal-poor red giant HD 88609 to determine the abundances of heavy elements. Nineteen neutron-capture elements are detected in the spectrum. Our analysis revealed that this object has large excesses of light neutron-capture elements, while heavy neutron-capture elements are deficient. The abundance pattern shows a continuously decreasing trend as a function of atomic number, from Sr to Yb, which is quite different from those in stars with excesses of r-process elements. Such an abundance pattern is very similar to that of HD 122563, which was studied in our previous work. The results indicate that the abundance pattern found in the two stars could represent the pattern produced by the nucleosynthesis process that provided light neutron-capture elements in the very early Galaxy. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Honda, Satoshi; Aoki, Wako; Ishimaru, Yuhri; Wanajo, Shinya

2007-09-01

270

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

271

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

272

?? angular-correlation analysis of 200Hg after cold-neutron capture  

NASA Astrophysics Data System (ADS)

We report on a ?? angular-correlation experiment investigating 200Hg after cold-neutron capture. The experiment was performed using eight high-purity germanium detectors mounted on an array installed at the PF1B neutron beam line of the research reactor of the Institut Laue-Langevin in Grenoble, France. The geometry of the array allows ?? angular-correlation analyses that can be used for the determination of level spins and multipole mixing ratios in 200Hg. We present multipole mixing ratios for secondary ? rays and investigate the nature of the 200Hg neutron-capture state by analyzing the observed primary ? rays of this nucleus.

Bernards, C.; Urban, W.; Jentschel, M.; Mrkisch, B.; Jolie, J.; Fransen, C.; Kster, U.; Materna, T.; Simpson, G. S.; Thomas, T.

2011-10-01

273

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

274

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

PubMed

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 (157Gd) 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 125I, 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 157Gd-DNA ligands therefore have potential in NCT. The thermal neutron capture cross section of 157Gd, a nonradioactive isotope, is more than 50 times that of 10B. PMID:2678082

Martin, R F; D'Cunha, G; Pardee, M; Allen, B J

1989-01-01

275

Measurements of neutron capture cross section for 207,208Pb  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

276

Radiative Capture of Neutrons in the Kev Region.  

National Technical Information Service (NTIS)

Essentially monoenergetic neutrons with keV energies can be obtained from a reactor by using suitable filters. To date, prompt gamma -ray spectra have been measured using 24-, 2-, and 1-keV neutrons, obtained through Fe + Al + S, Sc + Ti and exp 6 Li filt...

R. C. Greenwood R. E. Chrien K. Rimawi

1975-01-01

277

Early history of development of boron neutron capture therapy of tumors.  

PubMed

The stable isotope 10B has a peculiarly marked avidity to capture slow neutrons whereupon it disintegrates into a lithium and a helium atom. These give up the 2.4 MeV of disintegration energy which they share within 5 and 9 microns of the 10B atom respectively. This means that the cell closest to the 10B atom bears the brunt of its atomic explosion. The objective of the tumor therapist is to find a carrier molecule for the boron atom which will concentrate in the tumor. Although a number of investigators saw the peculiar advantage of this selective tactic to achieve destruction of a species of unwanted cells, no success in animal studies was achieved until 1950. Sweet and colleagues found that the capillary blood-brain barrier keeps many substances out of the normal brain but that the gliomas had much less of such a barrier. He, Brownell, Soloway and Hatanaka in Boston together with Farr. Godwin, Robertson, Stickley. Konikowski and others at the Brookhaven. National Laboratory worked partially in collaboration and partly independently. We irradiated at 3 nuclear reactors several series of glioma patients with no long-term remission, much less a cure being achieved. Hatanaka on his return to Japan kept BNCT alive by treating a total of 140 patients with various brain tumors. Beginning in 1972, Mishima and colleagues have achieved useful concentrations of 10B-borono-phenylalanine, an analogue of the melanin precursor tyrosine, for BNCT of melanomas. PMID:9151220

Sweet, W H

1997-05-01

278

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

279

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

280

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

281

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

282

Dosimetry of the boron neutron capture reaction for BNCT and BNCEFNT.  

PubMed

The use of paired proportional counters, constructed from A-150 tissue equivalent plastic (TEP) and A-150 TEP loaded with an appropriate amount of 10B (50 to 200 ppm), for the dosimetry of the boron neutron capture reaction has been investigated for several years at the Gershenson Radiation Oncology Center. This method has been used for determining the dose components (fast neutron, gamma ray and boron capture product dose) in both Boron Neutron Capture Therapy (BNCT) beams and in beams proposed for boron neutron capture enhancement of fast neutron therapy (BNCEFNT). A disadvantage of this method, when standard 1/2" diameter Rossi type proportional counters are used, is that the beam intensity must be relatively low in order to avoid saturation effects (pulse pile-up) in the counter. This is a major problem if measurements are to be made in a reactor beam, since reducing the beam intensity generally results in a change in the neutron spectrum. In order to overcome this problem, miniature cylindrical proportional counters have been developed which may be used in high intensity beams. The operational characteristics of these counters are compared with the standard 1/2" spherical counters. A further disadvantage of proportional counters is the relatively long time it takes to collect data, particularly if detailed information (depth-dose curves and beam profiles) is required. This problem could be overcome by using a set of ionization chambers (an A-150 TEP chamber, a Mg chamber and a Mg chamber with a 25 microns boron loaded inner wall) which can be scanned in a water phantom. After calibration against the paired proportional counters it should be possible to extract the fast neutron, gamma ray and boron neutron capture product doses from measurements made with these three ionization chambers. A set of such chambers has been used to make preliminary measurements in a fast neutron beam and the results of these measurements are presented. PMID:10394417

Burmeister, J; Kota, C; Maughan, R L

1999-06-01

283

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

284

Neutron scattering reveals extremely slow cell water in a Dead Sea organism  

PubMed Central

Intracellular water dynamics in Haloarcula marismortui, an extremely halophilic organism originally isolated from the Dead Sea, was studied by neutron scattering. The water in centrifuged cell pellets was examined by means of two spectrometers, IN6 and IN16, sensitive to motions with time scales of 10 ps and 1 ns, respectively. From IN6 data, a translational diffusion constant of 1.3 10?5 cm2 s?1 was determined at 285 K. This value is close to that found previously for other cells and close to that for bulk water, as well as that of the water in the 3.5 M NaCl solution bathing the cells. A very slow water component was discovered from the IN16 data. At 285 K the water-protons of this component displays a residence time of 411 ps (compared with a few ps in bulk water). At 300 K, the residence time dropped to 243 ps and was associated with a translational diffusion of 9.3 10?8 cm2 s?1, or 250 times lower than that of bulk water. This slow water accounts for ?76% of cell water in H. marismortui. No such water was found in Escherichia coli measured on BSS, a neutron spectrometer with properties similar to those of IN16. It is hypothesized that the slow mobility of a large part of H. marismortui cell water indicates a specific water structure responsible for the large amounts of K+ bound within these extremophile cells.

Tehei, Moeava; Franzetti, Bruno; Wood, Kathleen; Gabel, Frank; Fabiani, Elisa; Jasnin, Marion; Zamponi, Michaela; Oesterhelt, Dieter; Zaccai, Giuseppe; Ginzburg, Margaret; Ginzburg, Ben-Zion

2007-01-01

285

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

286

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

287

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

288

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

289

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

290

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

291

Comparison of the gamma-ray spectra from 2. 8keV neutron capture and thermal-neutron capture in sodium-23  

Microsoft Academic Search

The gamma-ray spectrum resulting from neutron capture in the 2.8-keV resonance of ²³Na has been measured with the high-resolution annihilation pair spectrometer at the internal-target facility of the CP-5 reactor. The 2.8-keV resonance was populated by using the boron-shielded target technique: A ¹\\/-in.-thick filter of ¹°B surrounding the sodium sample selectively removes low-energy neutrons from the spectrum; the 1\\/E dependence

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

1977-01-01

292

Radiation effect of gadolinium-neutron capture reactions on the survival of Chinese hamster cells.  

PubMed

In gadolinium-neutron capture reactions, prompt gamma rays with an energy spectrum of up to 7 MeV, X-rays and electrons are released. We measured the effect of radiation as a result of capture reactions on cultured Chinese hamster cells. Cells in the medium containing 5000 ppm gadolinium were exposed to thermal neutrons from a nuclear reactor. The survival curve for those cells exhibited a shoulder in the low neutron fluence region. The survival curve for cells exposed to thermal neutrons in the absence of gadolinium was a simple exponential function. To obtain 10% survival levels, 5.4 x 10(12) neutrons/cm2 were required for cells irradiated in the absence of gadolinium, and 1.55 x 10(12) neutrons/cm2 for those irradiated in the presence of gadolinium. The therapeutic ratio in gadolinium-neutron capture therapy depends on the difference in 157Gd concentrations between the tumor and normal tissues. Thus, our current effort has been to develop a method of selectively delivering 157Gd to tumors. PMID:2267661

Akine, Y; Tokita, N; Matsumoto, T; Oyama, H; Egawa, S; Aizawa, O

1990-12-01

293

Characterisation of neutron and gamma-ray emission from thick target Be(p,n) reaction for boron neutron capture therapy  

Microsoft Academic Search

Low energy accelerator-based neutron sources have promising potential for use in a clinical treatment of cancer with boron neutron capture therapy (BNCT) and boron neutron capture synovectomy (BNCS). Such sources often utilise a thick target Be(p,n) reaction using incident proton energies from several hundred keV to 12 MeV above the reaction threshold of 2.06 MeV. The resulting neutron and gamma-ray

J Guzek; W. R McMurray; T Mateva; C. B Franklyn; U. A. S Tapper

1998-01-01

294

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

295

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

296

Neutron-capture gamma-ray data for obtaining elemental abundances from planetary spectra.  

SciTech Connect

Determination of elemental abundances is a top scientific priority of most planetary missions. Gamma-ray spectroscopy is an excellent method to determine elemental abundances using gamma rays made by nuclear reactions induced by cosmic-ray particles and by the decay of radioactive nuclides [Re73,Re78]. Many important planetary gamma rays are made by neutron-capture reactions. However, much of the data for the energies and intensities of neutron-capture gamma rays in the existing literature [e.g. Lo81] are poor [RF99,RF00]. With gamma-ray spectrometers having recently returned data from Lunar Prospector and NEAR and soon to be launch to Mars, there is a need for good data for neutron-capture gamma rays.

Reedy, Robert; Frankle, S. C. (Stephanie C.)

2001-01-01

297

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

NASA Technical Reports Server (NTRS)

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

Lugmair, G. W.; Marti, K.

1971-01-01

298

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.; Ache, 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

299

(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

300

(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

301

Stellar neutron capture rates - key data for the s process  

NASA Astrophysics Data System (ADS)

Neutron reactions are responsible for the formation of the elements heavier than iron. The corresponding scenarios relate to the He- and C- burning phases of stellar evolution (s process) and to supernova explosions (r and p processes). The s process, which is characterized by low neutron densities, operates in or near the valley of ? stability and has produced about half of the elemental abundances between Fe and Bi in the solar system and in the Universe. Because the s abundances are essentially determined by the (n, ?) cross sections along the reaction path, accurate neutron data constitute the key input for s process studies. Important constraints for the physical conditions at the stellar sites can be inferred by comparison of the abundance patterns from current s-process models with solar system material or presolar grains. The experimental methods for the determination of stellar (n, ?) rates are outlined at the example of recent cross section measurements and remaining quests will be discussed with respect to existing laboratory neutron sources and new developments.

Kppeler, F.

2013-12-01

302

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

303

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

SciTech Connect

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

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

2009-01-01

304

High-Resolution Neutron Total and Capture Cross-Section Measurements on 206Pb  

Microsoft Academic Search

High-resolution neutron total and capture cross-section measurements have been performed on a 99.82% enriched 206Pb metallic sample. The transmission and capture measurements were carried out at the 25- and 60-m stations, respectively, of the Time-Of-Flight facility GELINA of the IRMM in Geel (B). The small amount of material allowed us to detect 13 resonances below 80 keV in the transmission

A. Borella; A. Brusegan; M. C. Moxon; G. Aerts; F. Gunsing; P. Schillebeeckx

2005-01-01

305

Neutron Capture gamma-Rays from Titanium, Chromium, Iron, Nickel, and Zinc  

Microsoft Academic Search

The neutron capture gamma-rays emitted by the even-charge elements, from titanium to zinc, have been investigated with the aid of a pair spectrometer. Titanium emits a very simple spectrum. Two strong gamma-rays, 6.756+\\/-0.006 and 6.412+\\/-0.006 Mev, are produced by capture in Ti48. Neither the direct transition to the ground state of Ti49, nor the transitions to the ground states of

B. B. Kinsey; G. A. Bartholomew

1953-01-01

306

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

Microsoft Academic Search

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,

Hans Lundqvist; Per Munck af Rosenschoeld; Arash Rezaei; Shirin A. Enger

2006-01-01

307

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

SciTech Connect

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

Ackermann, A.L. (ed.)

1990-07-01

308

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

Microsoft Academic Search

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

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

2005-01-01

309

Gamma Rays from Thermal and Resonance Neutron Capture in Sb121 and Sb123  

Microsoft Academic Search

Prompt high-energy gamma rays resulting from neutron capture at thermal energies and in the resonances of Sb121 and Sb123 have been studied with the high flux beam reactor fast chopper using high-resolution Ge(Li) detectors. The binding energy Bn of the last neutron in Sb122 and Sb124 has been determined to be 6807 +\\/- 2 and 6468 +\\/- 2 keV, respectively.

M. R. Bhat; R. E. Chrien; D. I. Garber; O. A. Wasson

1970-01-01

310

Comparison of Radiation Effects of Gadolinium and Boron Neutron Capture Reactions  

Microsoft Academic Search

Purpose: Cell survival assays were performed to evaulate the effects of radiations released during neutron capture reactions by radolinium-157, boron-10 and by the combination of both. Materials and Methods: Single cell suspensions with or without Gd-157 and\\/or B-10 were exposed to thermal neutrons produced by the Kyoto University reactor, and standard cell survival curves were obtained. Results: Under the same

Koichi Tokuuye; Nobuhiko Tokita; Yasuyuki Akine; Hidetsugu Nakayama; Yoshinori Sakurai; Tooru Kobayashi; Keiji Kanda

2000-01-01

311

Nuclear Levels in 233Th Excited by Neutron Capture and (d, p) Reactions  

Microsoft Academic Search

Low-energy gamma rays of the reaction 232Th(n, gamma)233Th have been measured with the Ris bentcrystal spectrometer and with a Ge(Li) spectrometer at Munich. High-energy neutron-capture gamma rays from four low-energy neutron resonances have been investigated at the fastchopper facility at Brookhaven. Data on the reaction 232Th(d, p)233Th were taken with an Enge split-pole magnetic spectrograph at the tandem Van de

T. von Egidy; O. W. Schult; D. Rabenstein; J. R. Erskine; O. A. Wasson; R. E. Chrien; D. Breitig; R. P. Sharma; H. A. Baader; H. R. Koch

1972-01-01

312

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

Microsoft Academic Search

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

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

1982-01-01

313

Design of neutron beams for neutron capture therapy using a 300-kW slab TRIGA reactor  

SciTech Connect

A design for a slab reactor to produce an epithermal neutron beam and a thermal neutron beam for use in neutron capture therapy (NCT) is described. A thin reactor with two large-area faces, a ``slab`` reactor, was planned using eighty-six 20% enriched TRIGA fuel elements and four B{sub 4}C control rods. Two neutron beams were designed: an epithermal neutron beam from one face and a thermal neutron beam from the other. The planned facility, based on this slab-reactor core with a maximum operating power of 300 kW, will provide an epithermal neutron beam of 1.8 {times} 10{sup 9} n{sub epi}/cm{sup 2}{center_dot}s intensity with low contamination by fast neutrons and gamma rays and a thermal neutron beam of 9.0 {times} 10{sup 9}n{sub th}/cm{sup 2}{center_dot}s intensity with low fast-neutron dose and gamma dose. Both neutron beams will be forward directed. Each beam can be turned on and off independently through its individual shutter. A complete NCT treatment using the designed epithermal or thermal neutron beam would take 30 or 20 min, respectively, under the condition of assuming 10{mu}g {sup 10}B/g in the blood. Such exposure times should be sufficiently short to maintain near-optimal target (e.g., {sup 10}B, {sup 157}Gd, and {sup 235}U) distribution in tumor versus normal tissues throughout the irradiation. With a low operating power of 300 kW, the heat generated in the core can be removed by natural convection through a pool of light water. The proposed design in this study could be constructed for a dedicated clinical NCT facility that would operate very safely.

Liu, H.B. [Brookhaven National Lab., Upton, NY (United States). Medical Dept.

1995-03-01

314

On the capture of dark matter by neutron stars  

NASA Astrophysics Data System (ADS)

We calculate the number of dark matter particles that a neutron star accumulates over its lifetime as it rotates around the center of a galaxy, when the dark matter particle is a self-interacting boson but does not self-annihilate. We take into account dark matter interactions with baryonic matter and the time evolution of the dark matter sphere as it collapses within the neutron star. We show that dark matter self-interactions play an important role in the rapid accumulation of dark matter in the core of the neutron star. We consider the possibility of determining an exclusion region of the parameter space for dark matter mass and dark matter interaction cross section with the nucleons as well as dark matter self-interaction cross section, based on the observation of old neutron stars. We show that for a dark matter density of 103 GeV/cm3and dark matter mass m? lesssim 10 GeV, there is a potential exclusion region for dark matter interactions with nucleons that is three orders of magnitude more stringent than without self-interactions. The potential exclusion region for dark matter self-interaction cross sections is many orders of magnitude stronger than the current Bullet Cluster limit. For example, for high dark matter density regions, we find that for m? ~ 10 GeV when the dark matter interaction cross section with the nucleons ranges from ??n ~ 10-52 cm2 to ??n ~ 10-57 cm2, the dark matter self-interaction cross section limit is ??? lesssim 10-33 cm2, which is about ten orders of magnitude stronger than the Bullet Cluster limit.

Gver, Tolga; Emre Erkoca, Arif; Hall Reno, Mary; Sarcevic, Ina

2014-05-01

315

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

PubMed

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. PMID:16485408

Enger, Shirin A; Rezaei, Arash; Munck af Rosenschld, Per; Lundqvist, Hans

2006-01-01

316

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

317

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

NASA Astrophysics Data System (ADS)

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

Varhue, Walter John

318

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

319

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

SciTech Connect

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

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

1989-08-15

320

Electron capture in core-collapse supernovae investigated through configuration mixing in neutron-rich nuclei  

NASA Astrophysics Data System (ADS)

Electron capture on neutron-rich medium-mass nuclei is a key process where the electrons that impede the collapse of the core of massive stars are captured, thereby producing very neutron-rich nuclei. As the core collapses, the supernova is then initiated. For the electron capture to proceed, however, the allowed Gamow-Teller (GT) transition must be unblocked either by thermal excitations or by mixing of proton configurations from a higher-lying shell into the ground-state configuration of the nucleus. The present paper presents an experiment performed at the National Superconducting Cyclotron Laboratory at Michigan State University, in which we study the configuration mixing in the neutron-rich76Zn isotope. The experiment utilised single-proton and single-neutron knockout with detection of reaction-residue ? rays and measurement of the parallel momentum of the residue. Through this we investigate the proton components of the 76Zn ground state, with a particular interest in ?-g9/2, which may unblock the GT electron capture even at low temperatures and thereby open a new pathway for the initiation of the collapse of the pre-supernova stellar core.

Diget, C. Aa; Baugher, T.; Bazin, D.; Bentley, M. A.; Berryman, J. S.; Brown, J. R.; Chipps, K. A.; Davies, P. J.; Fulton, B. R.; Gade, A.; Iwasaki, H.; Laird, A. M.; Lemasson, A.; McDaniel, S.; Ratkiewicz, A.; Scruton, L.; Shore, A.; Stroberg, S. R.; Weisshaar, D.; Wimmer, K.; Winkler, R.

2012-09-01

321

Procedures for implementation of the MIT program on neutron capture therapy  

Microsoft Academic Search

This paper describes the written procedures adopted by the Massachusetts Institute of TEchnology (MIT) and the New England Medical Center (NEMC) to implement their neutron capture therapy program. The procedures are sufficiently flexible enough to accommodate the differing needs of each patient. Twenty eight procedures were prepared to implement the program.

1995-01-01

322

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

323

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

324

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

325

Dosimetric evaluation of neutron capture therapy for local advanced breast cancer  

Microsoft Academic Search

Local recurrence breast cancer is one of the most difficult conditions to cure and there is a need for new therapy. If sufficient boron compound can be targeted to the tumor, boron neutron capture therapy (BNCT) can be applied to local recurrent breast cancer. In this study, we performed a preliminary dosimetry with a phantom model of the mammary gland

H. Yanagie; H. Kumada; Y. Sakurai; T. Nakamura; Y. Furuya; H. Sugiyama; K. Ono; S. Takamoto; M. Eriguchi; H. Takahashi

2009-01-01

326

Neutron-Capture Elements in the Very Metal Poor Star HD 122563  

NASA Astrophysics Data System (ADS)

We obtained high-resolution, high signal-to-noise ratio (S/N) spectroscopy for the very metal poor star HD 122563 with the Subaru Telescope High Dispersion Spectrograph. Previous studies have shown that this object has excesses of light neutron-capture elements, while its abundances of heavy ones are very low. In our spectrum, which covers 3070-4780 of this object, 19 neutron-capture elements have been detected, including seven for the first time in this star (Nb, Mo, Ru, Pd, Ag, Pr, and Sm). Upper limits are given for five other elements including Th. The abundance pattern shows a gradually decreasing trend, as a function of atomic number, from Sr to Yb, which is quite different from those in stars with excesses of r-process elements. This abundance pattern of neutron-capture elements provides new strong constraints on the models of nucleosynthesis responsible for the very metal poor stars with excesses of light neutron-capture elements but without enhancement of heavy ones. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Honda, S.; Aoki, W.; Ishimaru, Y.; Wanajo, S.; Ryan, S. G.

2006-06-01

327

Lu-Hf Evolution of the Moon Importance of Neutron Capture Effects  

NASA Astrophysics Data System (ADS)

New Hf-isotope and Lu-Hf data show that neutron capture (NC) has falsified the measured Lu-Hf systematics in 9 out of 13 analyzed lunar rock samples. This frequent occurrence of NC effects calls for a reinvestigation of the lunar Lu-Hf systematics.

Sprung, P.; Kleine, T.; Scherer, E. E.

2012-03-01

328

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

NASA Astrophysics Data System (ADS)

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

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

2001-03-01

329

Gadolinium dosimetry, a problematic issue in the neutron capture therapy. Comparison between experiments and computational simulations  

Microsoft Academic Search

In GdNCT the interested isotope is 157Gd that captures neutrons with (n, ) reaction and also emits internal conversion and Auger electrons. These electrons have an important effect on DNA strands, mainly due to the property of gadolinium to link to DNA. The emitted gamma rays partially interacts with tumours but mainly diffuse in the body damaging healthy tissues. Therefore

D. Bufalino; N. Cerullo; V. Colli; G. Gambarini; G. Rosi

2006-01-01

330

Identification of Nuclear Levels of {sup 34}S for Determination of the Neutron Capture Cross Section  

SciTech Connect

We are developing a new method to identify nuclear levels based on neutron capture reactions, named 'TELLA-2.' Measured data of prompt gamma rays from {sup 33}S(n,{gamma}){sup 34}S was used to improve the method. We will show how we obtain candidates of nuclear levels.

Kin, Tadahiro; Oshima, Masumi; Furutaka, Kazuyoshi; Koizumi, Mitsuo; Toh, Yosuke; Kimura, Atsushi [Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki-ken, 319-1195 (Japan)

2009-01-28

331

DANCE (Detector for Advanced Neutron Capture Experiments) is a 4pi array of BaF2 crystals installed at LANSCE, Lujan Center. Neutron capture measurements on ^157Gd and ^89Y nuclei were conducted using this facility  

Microsoft Academic Search

DANCE (Detector for Advanced Neutron Capture Experiments) is a 4pi array of BaF2 crystals installed at LANSCE, Lujan Center. Neutron capture measurements on ^157Gd and ^89Y nuclei were conducted using this facility. The absolute cross sections of the ^89Y(n,gamma) reaction was measured for the first time ever in the neutron energy range of 10 eV -- 10 keV and improvements

A. Chyzh; G. Mitchell; D. Vieira; T. Bredeweg; J. Ullmann; M. Jandel; A. Couture; A. Keksis; R. Rundberg; J. Wilhelmy; J. O'Donnell; B. Baramsai; R. Haight; J. Wouters; M. Krticka; W. Parker; J. Becker; U. Agvaanlusan

2009-01-01

332

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

333

Medical application of neutron capture. gamma. -ray spectroscopy: measurement of cadmium and nitrogen in living human subjects. [¹¹³Cd, ¹⁴N, ¹⁵N  

Microsoft Academic Search

In-vivo measurement of small quantities of Cd is possible due to the high radiative neutron-capture cross-section of ¹¹³Cd (12.3%, 20000 b). Under slow neutron capture in ¹¹³Cd, the excited ¹¹⁴Cd decays by prompt emission of cascade of gamma-rays of which the most intense is the 559 keV transition from the first excited state to the ground state. For a total

D. Vartsky; K. J. Ellis; S. H. Cohn

1978-01-01

334

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

335

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

336

Parametrization of low-energy cross sections for nonresonant neutron capture  

SciTech Connect

The nonresonant component of radiative neutron capture reactions is parametrized at low energies by a polynomial of second degree. The potential model is first used to reproduce experimental data below 1 MeV with the help of spectroscopic factors. The fits are found sensitive to the scattering length of the initial s or p waves. The coefficients of a Taylor expansion are then calculated by resolution of the Schroedinger equation and its energy derivatives at energy zero. Such theory-guided parametrizations are derived for neutron capture by {sup 7}Li, {sup 12}C, {sup 14}C, {sup 16}O, and {sup 18}O. When the capture proceeds from the s wave to a weakly bound state, a Pade-like parametrization better approximates the potential-model results.

Wang Chengbin [Shanghai Institute of Applied Physics, Chinese Academy of Science, Shanghai 201800 (China); Cisse, Ousmane I. [UFR SEA, Departement de Physique, Universite de Ouagadougou, 03 BP 7021 Ouagadougou 03 (Burkina Faso); Baye, Daniel [Physique Quantique, C. P. 165/82, and Physique Nucleaire Theorique et Physique Mathematique, C. P. 229, Universite Libre de Bruxelles, B-1050 Brussels (Belgium)

2009-09-15

337

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

NASA Astrophysics Data System (ADS)

An Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) at the beam line 04 of MLF (Material and Life Sciences Experimental Facilities) of J-PARC (Japan Proton Accelerator Research Complex) was installed to measure neutron capture cross sections related to the research and development of innovative nuclear systems, the study on nuclear astrophysics, etc. ANNRI has two gamma-ray spectrometers: one is a Ge detector array placed at 22 m from the coupled type moderator of the spallation neutron source of J-PARC/MLF and the other is a pair of NaI(Tl) detectors at 28 m. Until the 11th of March, 2011, when we had big earthquakes, we measured capture cross sections of Zr-93, Tc-99, Pd-107, I-129, Cm-244, Cm-246, etc. After checking and repairing ANNRI, we restarted measurements, and ANNRI has been open to worldwide users at present.

Igashira, Masayuki; Harada, Hideo; Kiyanagi, Yoshiaki

2012-11-01

338

Determination of mean squared slowing-down distance for Am-Be neutrons in water using BF3-detector  

Microsoft Academic Search

The mean squared slowing-down distance (Flux Age) and relaxation length have been measured in water using Am-Be neutron source. With BF3-proportional detector the mean squared slowing-down distance was determined at cadmium resonance of 0.6 eV. The epithermal and thermal fluxes as a function of distance from source dipped in water were measured. The relaxation length for Am-Be source is 10.8

Nasir M. Mirza; Sikander M. Mirza; Masood Iqbal

1996-01-01

339

Determination of mean squared slowing-down distance for Am?Be neutrons in water using BF 3-detector  

Microsoft Academic Search

The mean squared slowing-down distance (Flux Age) and relaxation length have been measured in water using Am?Be neutron source. With BF3-proportional detector the mean squared slowing-down distance was determined at cadmium resonance of 0.6 eV. The epithermal and thermal fluxes as a function of distance from source dipped in water were measured. The relaxation length for Am?Be source is 10.8

Nasir M. Mirza; Sikander M. Mirza; Masood Iqbal

1996-01-01

340

Anomalous Neutron Capture and Plastic Deformation of cu and pd Cathodes during Electrolysis in a Weak Thermalized Neutron Field:. Evidence of Nuclei-Lattice Exchange  

Microsoft Academic Search

Anomalous neutron capture and plastic deformation in the hardened Cu and Pd cathodes has been established under combined action of electrolysis and a weak thermalized neutron field (WTNF) with a flux in the range of 180-400 n\\/s cm2. Experiments with these cathodes showed ~7.0% decrease in the 2224 keV n-D gamma peak accompanying thermalized neutron capture inside the PE cavity

A. G. Lipson; G. H. Miley

2006-01-01

341

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

342

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

SciTech Connect

The non-surgical brain cancer treatment modality, Boron Neutron Capture Therapy (BNCT), requires the use of an epithermal neutron beam. This purpose of this thesis was to design an epithermal neutron beam at the University of Virginia Research Reactor (UVAR) suitable for BNCT applications. A suitable epithermal neutron beam for BNCT must have minimal fast neutron and gamma radiation contamination, and yet retain an appreciable intensity. The low power of the UVAR core makes reaching a balance between beam quality and intensity a very challenging design endeavor. The MCNP monte carlo neutron transport code was used to develop an equivalent core radiation source, and to perform the subsequent neutron transport calculations necessary for beam model analysis and development. The code accuracy was validated by benchmarking output against experimental criticality measurements. An epithermal beam was designed for the UVAR, with performance characteristics comparable to beams at facilities with cores of higher power. The epithermal neutron intensity of this beam is 2.2 {times} 10{sup 8} n/cm{sup 2} {center_dot} s. The fast neutron and gamma radiation KERMA factors are 10 {times} 10{sup {minus}11}cGy{center_dot}cm{sup 2}/n{sub epi} and 20 {times} 10{sup {minus}11} cGy{center_dot}cm{sup 2}/n{sub epi}, respectively, and the current-to-flux ratio is 0.85. This thesis has shown that the UVAR has the capability to provide BNCT treatments, however the performance characteristics of the final beam of this study were limited by the low core power.

Burns, T.D. Jr.

1995-05-01

343

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

344

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

PubMed

Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent ?(Q) is independent of the wavevector transfer Q in the measured Q range and (ii) the structural relaxation time ?(Q) follows a power-law dependence on Q. Consequently, the Q-independent structural relaxation time ?(0) can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of ?(0) can be fitted with the mode-coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by Tokuyama in the measured temperature range. The calculated dynamic response function ?(T)(Q, t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement ?x(2)? and the non-Gaussian parameter ?(2) extracted from the elastic scattering. PMID:22277723

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

2012-02-15

345

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

SciTech Connect

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

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

2011-01-01

346

Low-energy neutron capture reactions via the surrogate method  

NASA Astrophysics Data System (ADS)

Indirect methods, such as the surrogate approach, play a crucial role in determining cross sections for reactions on unstable nuclei. In a surrogate experiment, the compound nucleus of interest is produced using a light-ion direct reaction on a target that is easier to produce. The decay of the compound nucleus is measured in coincidence with the outgoing direct-reaction particle and the coincidence probabilities are used to infer the desired cross sections. The method is expected to play an important role in cross-section measurements with radioactive ion beams (RIBs), since inverse-kinematics experiments cannot be performed on a neutron target. For example, if one measures (d,p?) instead of (n,?), one carries out a surrogate measurement. To make full use of radioactive-beam capabilities, the inverse-kinematics surrogate method needs to be developed further. This presentation summarizes recent applications of the surrogate approach to (n,?) reactions. The limitations of frequently-employed approximation schemes will be discussed, as well as progress made in moving beyond these limitations. Results will be shown for the gadolinium region.

Escher, Jutta; Burke, Jason; Dietrich, Frank; Ressler, Jo; Scielzo, Nicholas; Thompson, Ian

2010-11-01

347

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

SciTech Connect

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

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

2005-05-24

348

Stellar neutron capture cross section of the unstable s-process branching point {sup 151}Sm  

SciTech Connect

The neutron capture cross sections of the radioactive isotope {sup 151}Sm and of natural samarium have been measured in the energy range from 3 keV to 225 keV at the Karlsruhe 3.7 MV Van de Graaff accelerator. Neutrons were produced via the {sup 7}Li(p,n){sup 7}Be reaction by bombarding metallic Li targets with a pulsed proton beam and capture events were registered with the Karlsruhe 4{pi} Barium Fluoride Detector. The cross sections were determined relative to the gold standard using a 206 mg sample of samarium oxide with 90% enrichment in {sup 151}Sm. Over most of the measured energy range uncertainties of {approx}2-3% could be achieved for the {sup 151}Sm/{sup 197}Au ratio. Maxwellian averaged neutron capture cross sections of {sup 151}Sm were calculated for thermal energies between kT = 8 keV and 100 keV with due consideration of the stellar enhancement factor and were found to be systematically larger than all previous theoretical predictions used in the analysis of the s-process branching at {sup 151}Sm. In the context of the branching analysis, an experimental determination of the stellar enhancement factor due to captures in thermally excited states is proposed, and the tentative determination of the p-process residual of {sup 152}Gd and a few other cases is discussed.

Wisshak, K.; Voss, F.; Kaeppeler, F.; Krticka, M.; Raman, S.; Mengoni, A.; Gallino, R. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Faculty of Mathematics and Physics, Charles University, CZ-180 00 Prague (Czech Republic); Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831-6354 (United States); CERN, CH-1211 Geneva 23 (Switzerland) and IAEA, Nuclear Data Section, P.O. Box 100, A-1400 Vienna (Austria); Dipartimento di Fisica Generale, Universita di Torino, Sezione INFN di Torino, Via P. Giuria 1, I-10125 Turin (Italy) and Centre for Stellar and Planetary Astrophysics, School of Mathematical Sciences, Monash University 3800, Victoria (Australia)

2006-01-15

349

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

NASA Astrophysics Data System (ADS)

Observations of Very Metal-Poor stars indicate that there are at least two sites to r-process; "weak r-process" and "main r-process". A question is whether these two are well separated or there exists a variation in the r-process. We present the results of abundance analysis of neutron-capture elements in the two Very Metal-Poor stars HD107752 and HD110184 in the Milky Way halo observed with the Subaru Telescope HDS. The abundance patterns show overabundace at light n-capture elements (e.g. Sr, Y), inferring the element yielding of weak r-process, while heavy neutron-capture elements (e.g. Ba, Eu) are deficient; however, the overabundance of light ones is not as significant as that previously found in stars representing the weak r-process (e.g. HD122563; Honda et al. 2006). Our study show diversity in the abundance patterns from light to heavy neutron-capture elements in VMP stars, suggesting a variation in r-process, which may depend on electron fraction of environment.

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

2014-05-01

350

Neutron capture on {sup 94}Zr: Resonance parameters and Maxwellian-averaged cross sections  

SciTech Connect

The neutron capture cross sections of the Zr isotopes play an important role in nucleosynthesis studies. The s-process reaction flow between the Fe seed and the heavier isotopes passes through the neutron magic nucleus {sup 90}Zr and through {sup 91,92,93,94}Zr, but only part of the flow extends to {sup 96}Zr because of the branching point at {sup 95}Zr. Apart from their effect on the s-process flow, the comparably small isotopic (n,{gamma}) cross sections make Zr also an interesting structural material for nuclear reactors. The {sup 94}Zr (n,{gamma}) cross section has been measured with high resolution at the spallation neutron source n{sub T}OF at CERN and resonance parameters are reported up to 60 keV neutron energy.

Tagliente, G. [Istituto Nazionale di Fisica Nucleare (INFN), Bari (Italy); University of Gent (Belgium); Milazzo, P. M.; Fujii, K.; Abbondanno, U.; Belloni, F.; Moreau, C. [Istituto Nazionale di Fisica Nucleare (INFN), Trieste (Italy); Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Dridi, W.; Gunsing, F.; Pancin, J.; Perrot, L.; Plukis, A. [CEA/Saclay-IRFU, Gif-sur-Yvette (France); Alvarez, H.; Duran, I.; Paradela, C. [Universidade de Santiago de Compostela (Spain); Alvarez-Velarde, F.; Cano-Ott, D.; Embid-Segura, M. [Centro de Investigaciones Energeticas Medioambientales y Technologicas, Madrid (Spain)

2011-07-15

351

A calculational study of tangential and radial beams in HIFAR for neutron capture therapy.  

PubMed

It is generally accepted that for biological purposes a tangential neutron beam is preferable to a radial beam because of its lower gamma and fast neutron contamination. Nevertheless radial broad spectrum epithermal neutron beams are currently being considered for boron neutron capture therapy of deep-seated tumours since they have the potential to deliver a more intense dose. A calculational study of a conceptual tangential beam and a filtered radial beam in the DIDO type reactor HIFAR was undertaken. A two-dimensional transport code was used. The tangential beam was found to be superior in therapeutic gain at depth in tissue to an aluminium fluoride (AIF3) filtered radial beam, while the dose rates of the beams were comparable. PMID:2268250

Harrington, B V

1990-01-01

352

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

NASA Astrophysics Data System (ADS)

The dosimetry method based on Fricke-Xylenol-Orange-infused gels in form of layers has shown noticeable potentiality for in-phantom or in-free-beam dose and thermal flux profiling and imaging in the high fluxes of thermal or epithermal neutrons utilised for boron neutron capture therapy (BNCT). Gel-dosimeters in form of layers give the possibility not only of obtaining spatial dose distributions but also of achieving measurements of each dose contribution in neutron fields. The discrimination of the various dose components is achieved by means of pixel-to-pixel manipulations of pairs of images obtained with gel-dosimeters having different isotopic composition. It is possible to place large dosimeters, detecting in such a way large dose images, because the layer geometry of dosimeters avoids sensitive variation of neutron transport due to the gel isotopic composition. Some results obtained after the last improvements of the method are reported.

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

353

Dose calculation from a D-D-reaction-based BSA for boron neutron capture synovectomy.  

PubMed

Monte Carlo simulations were carried out to calculate dose in a knee phantom from a D-D-reaction-based Beam Shaping Assembly (BSA) for Boron Neutron Capture Synovectomy (BNCS). The BSA consists of a D(d,n)-reaction-based neutron source enclosed inside a polyethylene moderator and graphite reflector. The polyethylene moderator and graphite reflector sizes were optimized to deliver the highest ratio of thermal to fast neutron yield at the knee phantom. Then neutron dose was calculated at various depths in a knee phantom loaded with boron and therapeutic ratios of synovium dose/skin dose and synovium dose/bone dose were determined. Normalized to same boron loading in synovium, the values of the therapeutic ratios obtained in the present study are 12-30 times higher than the published values. PMID:19828325

Abdalla, Khalid; Naqvi, A A; Maalej, N; Elshahat, B

2010-01-01

354

Boron neutron capture therapy for the treatment of cerebral gliomas. I. Theoretical evaluation of the efficacy of various neutron beams.  

PubMed

The technique of boron neutron capture therapy in the treatment of cerebral gliomas depends upon the selective loading of the tumor with a 10B-enriched compound and subsequent irradiation of the brain with low-energy neutrons. The charged particles produced in the 10B (n,alpha) 7Li reaction have ranges in tissue of less than 10 mum so that the dose distribution closely follows the 10B distribution even to the cellular level. The effectiveness of this therapy procedure is dependent not only on the 10B compound but on the spectral characteristics of the neutron source as well. Hence, an optimization of these characteristics will increase the chances of therapeutic success. Transport calculations using a neutral particle transport code have been made to determine the dose-depth distributions within a simple head phantom for five different incident neutron beams. Comparison of these beams to determine their relative therapeutic efficacy was made by the use of a maximum useable depth criterion. In particular, with presently available compounds, the MIT reactor (MITR) therapy beam (a) is not inferior to a pure thermal neutron beam, (b) would be marginally improved if its gamma-ray contamination were eliminated, (c) is superior to a partially 10B-filtered MITR beam, and (d) produces a maximum useable depth which is strongly dependent upon the tumor-to-blood ratio of 10B concentrations and weakly dependent upon the absolute 10B concentration in tumor. A pure epithermal neutron beam with a mean energy of 37 eV is shown to have close to the optimal characteristics for boron neutron capture therapy. Futhermore, these optimal characteristics can be approximated by a judiciously D2O moderated and 10B-filtered 252Cf neutron source. This tailored 252Cf source would have at least a 1.5 cm greater maximum useable depth than the MITR therapy beam for realistic 10B concentrations. However, at least one gram of 252Cf would be needed to make this a practical therapy source. If the moderated 252Cf source is not 10B filtered, the resultant neutron beam has characteristics similar to those of the MITR beam with no gamma-ray contamination. For usch a beam, 100 mg of 252Cf would produce a flux of 2.4 X 10(8) neutrons/(cm2 sec), which is an intensity suitable for therapy applications. PMID:1186617

Zamenhof, R G; Murray, B W; Brownell, G L; Wellum, G R; Tolpin, E I

1975-01-01

355

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

NASA Technical Reports Server (NTRS)

High-precision W isotopic analyses by Harper and Jacobsen indicate the W-182/W-183 ratio in the Toluca iron meteorite is shifted by -(3.0 +/- 0.9) x 10(exp -4) relative to a terrestrial standard. Possible causes of this shift are neutron-capture reactions on W during Toluca's approximately 600-Ma exposure to cosmic ray particles or radiogenic growth of W-182 from 9-Ma Hf-182 in the silicate portion of the Earth after removal of W to the Earth's core. Calculations for the rates of neutron-capture reactions on W isotopes were done to study the first possibility. The LAHET Code System (LCS) which consists of the Los Alamos High Energy Transport (LAHET) code and the Monte Carlo N-Particle(MCNP) transport code was used to numerically simulate the irradiation of the Toluca iron meteorite by galactic-cosmic-ray (GCR) particles and to calculate the rates of W(n, gamma) reactions. Toluca was modeled as a 3.9-m-radius sphere with the composition of a typical IA iron meteorite. The incident GCR protons and their interactions were modeled with LAHET, which also handled the interactions of neutrons with energies above 20 MeV. The rates for the capture of neutrons by W-182, W-183, and W-186 were calculated using the detailed library of (n, gamma) cross sections in MCNP. For this study of the possible effect of W(n, gamma) reactions on W isotope systematics, we consider the peak rates. The calculated maximum change in the normalized W-182/W-183 ratio due to neutron-capture reactions cannot account for more than 25% of the mass 182 deficit observed in Toluca W.

Masarik, J.; Reedy, R. C.

1994-01-01

356

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

PubMed

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

Brayeur, Lionel; Tinyakov, Peter

2012-08-10

357

Neutron Slowing down and Transport in Monoisotopic Media with Constant Cross Sections or with a Square-Well Minimum.  

National Technical Information Service (NTIS)

A specialized moments-method computer code was constructed for the calculation of the even spatial moments of the scalar flux, phi/sub 2n/, through 2n = 80. Neutron slowing-down and transport in a medium with constant cross sections was examined and the e...

W. H. Peng

1977-01-01

358

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

PubMed

The feasibility of a pinhole camera system for online dosimetry in boron neutron capture therapy (BNCT) was studied. A prototype system was designed and built. Prompt ?-rays from the (10)B(n,?)(7)Li reaction from a phantom irradiated with neutrons were detected with the prototype system. An image was reconstructed from the experimental data. The reconstructed image showed a good separation of the two borated regions in the phantom. The counting rates and signal-to-noise ratio when using the system in actual BNCT applications are also discussed. PMID:24433991

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

2014-06-01

359

The measurements of parity violation in resonant neutron-capture reactions  

SciTech Connect

The study of parity violation in total (n,{gamma}) cross sections on {sup 139}La and {sup 117}Sn targets was performed at the LANSCE pulsed neutron source using longitudinally polarized neutrons and a BaF{sub 2} detector. The effect of parity nonconservation in the {sup 139}La(n,{gamma}) reaction for the resonance at E{sub n}=0.73 eV was confirmed. New results for p-wave resonances in the {sup 117}Sn(n, {gamma}) reaction were obtained. A comparison between the capture and transmission techniques is presented. 12 refs., 5 figs., 1 tab.

Sharapov, E.I.; Popov, Y.P. (Joint Inst. for Nuclear Research, Dubna (USSR)); Wender, S.A.; Seestrom, S.J.; Bowman, C.D. (Los Alamos National Lab., NM (USA)); Postma, H. (Technische Hogeschool Delft (Netherlands)); Gould, C.R. (North Carolina State Univ., Raleigh, NC (USA)); Wasson, A. (National Inst. of Standards and Technology, Gaithersburg, MD (USA))

1990-01-01

360

Dose response of the AIA rabbit stifle joint to boron neutron capture synovectomy.  

PubMed

This study assessed the treatment with boron neutron capture synovectomy of synovitis in the antigen-induced arthritis (AIA) model. A boron compound, potassium dodecahydrododeca-borate (K(2)B(12)H(12)), was injected into stifle joints of 24 AIA and 12 normal rabbits and activated by neutron bombardment of the joint to achieve doses from 800 to 81,000 RBE-cGy. Synovial ablation in the AIA joint was accomplished at doses of 6,000 to 7,000 RBE-cGy with no adverse effects to skin or extracapsular tissues. PMID:15219286

Shortkroff, Sonya; Binello, Emanuela; Zhu, Xuping; Gierga, David; Thornhill, Thomas S; Shefer, Ruth E; Jones, Alun G; Yanch, Jacquelyn C

2004-07-01

361

180Hf energy levels deduced from thermal and average resonance neutron-capture gamma-ray spectra  

Microsoft Academic Search

An energy level diagram for 180Hf is developed on the basis of neutron-capture gamma-ray spectroscopy. Both thermal neutron capture and average resonance neutron-capture studies were made with isotopically enriched and natural Hf samples. The energies and intensities of the high-energy 7.4-4.7 MeV primary gamma transitions and the intermediate-energy 2.1-0.5 MeV gamma transitions were made with the in-pile (n ,gamma) source

D. L. Bushnell; D. J. Buss; Robert K. Smither

1974-01-01

362

Gamma-ray asymmetry measurements in the capture of polarized cold neutrons on ^27Al  

NASA Astrophysics Data System (ADS)

We have measured parity-violating (PV) and parity-allowed (PA) asymmetries in the angular distribution of the gamma rays emitted from the capture of cold polarized neutrons in a solid Al target at the SNS Beam Line 13 at ORNL. The measurement is a part of the systematic studies of the NPDGamma experiment. About 20% of the detector signal in the NPDGamma is produced by neutrons captured in the Al walls and the beam windows of the liquid para-hydrogen target. Therefore it is necessary to measure the strength of PV and PA gamma-ray asymmetries in Al. The sources of instrumental and physical systematic errors in the measured Al data and the contributions of the strong and electromagnetic components of the spin-orbit interaction to the PA asymmetry were identified and will be discussed.

Balascuta, Septimiu

2012-10-01

363

10B quantitative determination in ppb range by particle tracks reading for boron neutron capture therapy  

Microsoft Academic Search

Quantitative determination of ppb-order 10B was carried out in a small number of cultured tumor cells by particle tracks by the 10B(n,)7Li reactions using solid state nuclear track detector (SSNTD) for boron neutron capture therapy research. The detection limit of 10B concentration in tumor cells is less than 110-3 ppm under our experimental conditions which permits the quantitative determination of

M. Takagaki; K. Ono; S. I. Masunaga; Y. Kinashi; Y. Sakurai; T. Kobayashi; S. I. Miyatake; N. Hashimoto

2001-01-01

364

Digital techniques for n \\/? pulse shape discrimination and capture-gated neutron spectroscopy using liquid scintillators  

Microsoft Academic Search

We have investigated the use of digital pulse processing techniques for n\\/? pulse shape discrimination (PSD) in liquid scintillators, and the application of these techniques to a capture-gated fast neutron monitor developed using the enriched 10B-loaded liquid scintillator BC523A. The motivation for this study has been to develop computationally fast digital PSD algorithms that can be implemented in a compact

S. D. Jastaniah; P. J. Sellin

2004-01-01

365

Analytical sensitivities and energies of thermal neutron capture gamma rays II  

USGS Publications Warehouse

A table of the analytical sensitivities of the principal lines in the thermal neutron capture gamma-ray spectrum from 0 to 3 MeV has been compiled for most of the elements. A tabulation of the full-energy, single-escape, and double-escape peaks has also been made according to energy. The tables are useful for spectral interpretation and calibration. ?? 1971.

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

1971-01-01

366

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

USGS Publications Warehouse

A table of the analytical sensitivities of the principal lines in the thermal-neutron-capture gamma ray spectrum has been compiled for most of the elements. In addition a second table of the full-energy, single-escape, and double-escape peaks has been compiled according to energy for all significant lines above 3 MeV. Lines that contrast well with adjacent lines are noted as prominent. The tables are useful for spectral interpretation and calibration. ?? 1970.

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

1970-01-01

367

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

PubMed

Boron neutron capture therapy (BNCT) with Na2B12H11SH (BSH) or p-dihydroxyborylphenylalanine (BPA), and with a combination of both, was compared to radiotherapy with temozolomide, and the number of patients required to show statistically significant differences between the treatments was calculated. Whereas arms using BPA require excessive number of patients in each arm, a two-armed clinical trial with BSH and radiotherapy plus temozolomide is feasible. PMID:24373823

Sander, Anja; Wosniok, Werner; Gabel, Detlef

2014-06-01

368

Boron-containing thiouracil derivatives for neutron-capture therapy of melanoma  

SciTech Connect

Boron-containing derivatives of 2-thiouracil and 2,4-dithiouracil and the corresponding 6-propyl compounds, containing a dihydroxyboryl group in the 5-position, have been prepared. These compounds accumulate in B16 melanoma in mice in concentrations up to 30 micrograms of boron per gram tissue. The uptake persists. The toxicity of both 2-thiouracil derivatives is low. These compounds are therefore good candidates for boron neutron-capture therapy of malignant melanoma.

Tjarks, W.; Gabel, D. (Univ. of Bremen (Germany, F.R.))

1991-01-01

369

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

Microsoft Academic Search

Purpose: Head and neck carcinomas that recur locally after conventional irradiation pose a difficult therapeutic problem. We evaluated safety and efficacy of boron neutron capture therapy (BNCT) in the treatment of such cancers. Methods and Materials: Twelve patients with inoperable, recurred, locally advanced (rT3, rT4, or rN2) head and neck cancer were treated with BNCT in a prospective, single-center Phase

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

2007-01-01

370

Parallelization of the Three-Dimensional Transport Equation for Boron Neutron Capture Therapy  

Microsoft Academic Search

We propose an asynchronous parallel algorithm for the linear Boltzmann transport equation in three dimensions, for Boron Neutron Capture Therapy (BNCT) radiation therapy planning, which can be implemented efficiently on shared memory parallel computers. The three-dimensional multigroup discrete ordinates transport equation is cast into a set of coupled two-dimensional equations, and discretization is accomplished on a grid of arbitrarily-shaped prismatic

Eric E. Aubanel; Faysal El Khettabi

2003-01-01

371

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

SciTech Connect

A neutron-capture experiment on {sup nat}Cd has been carried out at DANCE. Multiple-fold coincidence {gamma}-ray spectra have been collected from J=0, 1 resonances in {sup 111}Cd and {sup 113}Cd. The cascades ending at the ground state can be described by the SLO model while the cascades ending at the 2+ states are better reproduced by the mixed SLO+KMF model.

Rusev, Gencho Y. [Los Alamos National Laboratory

2012-08-27

372

Variations in Spectra of Resonance Neutron Capture Gamma Rays in Indium  

Microsoft Academic Search

Measurements are reported of the 0-350 kev portion of the gamma-ray spectra following neutron capture in the 1.46-, 3.86-, and 9.10-ev resonances of the 49In115 target nucleus. The prominent features of the spectra are significantly different for the three resonances as indicated by the ratios of relative intensities of the 67-, 98-, 188-, and 280-kev gamma rays. The 0-1600 kev

J. E. Draper; C. A. Fenstermacher; H. L. Schultz

1958-01-01

373

VARIATIONS IN SPECTRA OF RESONANCE NEUTRON CAPTURE GAMMA RAYS IN INDIUM  

Microsoft Academic Search

Measurements are reported of the 0 to 350 kev portion of the gamma-ray ; spectra following neutron capture in the 1.46-, 3.86-, and 9.10-ev resonances of ; the In¹¹⁵ target nucleus. The prominent features of the spectra ; are significantly different for the three resonances as indicated by the ratios ; of relative intensities of the 67-, 98-, 188-. and

J. E. Draper; C. A. Fenstermacher; H. L. Schultz

1958-01-01

374

53Cr(n, gamma) Transition energies and levels excited in thermal neutron capture  

Microsoft Academic Search

The nuclear level structure of 54Cr was studied by thermal-neutron capture gamma-ray spectroscopy of an enriched sample of 53Cr and compared with a natural chromium sample by means of a Ge(Li) spectrometer, using an external beam at the SAFARI-1 reactor. Eighty of the ninety observed transitions allocated to 54Cr (as compared with the previously observed total of 42) could be

C. Hofmeyr

1989-01-01

375

Neutron capture gamma-ray data and calculations for HPGe detector-based applications  

Microsoft Academic Search

Recently an IAEA Coordinated Research Project published an evaluation of thermal neutron capture gamma-ray cross sections, measured to 1-5% uncertainty, for over 80 elements [1] and produced the Evaluated Gamma-ray Activation File (EGAF) [2] containing nearly 35,000 primary and secondary gamma-rays is available from the IAEA Nuclear Data Section. We have begun an effort to model the quasi-continuum gamma-ray cascade

Dennis P. McNabb; Richard B. Firestone

2004-01-01

376

The E2 effective charge in low-energy neutron radiative capture  

Microsoft Academic Search

It is shown that the concept of effective charge can be used to explain low-energy neutron E2 radiative capture. The quantitative analyses of the 13C(eta, upsilo) at 0.1529MeV resonance and 20Ne(eta,gamma), 25Mg(eta,gamma) at thermal energy illustrate that an effective charge equal to 0.5e is required to explain the measured data. This value is consistent with that used for bound state

Yukun Ho

1986-01-01

377

A Feasibility Study on Multi Prompt-Gamma-Ray Telescope System for Boron Neutron Capture Therapy  

Microsoft Academic Search

We are improving the dose simulation system for boron neutron capture therapy (BNCT) and constructing the on-line dose-estimation\\u000a technique using the prompt gammaray telescope system. Our present telescope system counts the prompt gamma rays from hydrogen\\u000a which uniformly distributes in human body, and from boron-10 which locally distributes in target volume. However, this system\\u000a cannot get the detail information for

Y. Sakurai; H. Tanaka; M. Suzuki; G. Kashino; Y. Kinashi; S. Masunaga; K. Ono; A. Maruhashi

378

Theoretical Challenges of Determining Low-Energy Neutron Capture Cross Sections via the Surrogate Technique  

SciTech Connect

Cross sections for radiative neutron capture on unstable nuclei at low energies are difficult to calculate with high precision, and can be impossible to measure directly. It is therefore important to explore alternative methods. The prospects of one such method, the Surrogate Nuclear Reaction Technique, is currently being investigated at Lawrence Livermore National Laboratory. The purpose of this paper is to outline the strategy for combining the results from a surrogate experiment with theoretical calculations in order to extract the desired cross section.

Forssen, C; Ahle, L; Bernstein, L A; Church, J A; Dietrich, F S; Escher, J; Hoffman, R D

2004-07-15

379

High energy resolution measurement of the ²³⁸U neutron capture yield from 1 keV to 100 keV  

Microsoft Academic Search

The purpose of this work is the precise determination of the ²³⁸U neutron capture yield (i.e., the probability of neutron absorption) as a function of neutron energy with the highest available neutron energy resolution. The motivation for this undertaking arises from the central role played by the ²³⁸U neutron capture process in the calculation of the neutron balance of both

R. L. Macklin; R. B. Perez; G. de Saussure; R. W. Ingle

1988-01-01

380

Neutron-induced capture cross sections of short-lived actinides with the surrogate reaction method  

NASA Astrophysics Data System (ADS)

Determination of neutron-capture cross sections of short-lived nuclei is opening the way to understand and clarify the properties of many nuclei of interest for nuclear structure physics, nuclear astrophysics and particularly for transmutation of nuclear wastes. The surrogate approach is well-recognized as a potentially very useful method to extract neutron cross sections for low-energy compound-nuclear reactions and to overcome the difficulties related to the target radioactivity. In this work we will assess where we stand on these neutron-capture cross section measurements and how we can achieve the short-lived Minor Actinides nuclei involved in the nuclear fuel cycle. The CENBG collaboration applied the surrogate method to determine the neutron-capture cross section of 233Pa (T1/2 = 27 d). The 233Pa (n,?) cross section is then deduced from the measured gamma decay probability of 234Pa compound nucleus formed via the surrogate 232Th(3He,p) reaction channel. The obtained cross section data, covering the neutron energy range 0.1 to 1 MeV, have been compared with the predictions of the Hauser-Feshbach statistical model. The importance of establishing benchmarks is stressed for the minor actinides region. However, the lack of desired targets led us to propose recently the 174Yb (3He,p?) reaction as a surrogate reaction for the (n,?) predetermined benchmark cross section of 175Lu. An overview of the experimental setup combining gamma ray detectors such as Ge and C6D6 in coincidence with light charged particles ?E-E Telescopes will be presented and preliminary results will be discussed.

Ache, M.; Boutoux, G.; Jurado, B.; Barreau, G.; Matthieu, L.; Czajkowski, S.; Dassie, D.; Haas, B.; Mot, V.; Roig, O.; Gaudefroy, L.; Taieb, J.; Pillet, N.; Faul, T.; Srot, O.; Bauge, E.; Gunsing, F.

2010-03-01

381

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

SciTech Connect

The boron-containing melanin precursor analogue p-boronophenylalanine (BPA) has previously been shown to selectively deliver boron to pigmented murine melanomas when administered in a single intragastric dose. If boron neutron capture therapy is to become a clinically useful method of radiation therapy for human malignant melanoma, the boron carrier must be capable of delivering useful amounts of boron to remote tumor sites (metastases) and to poorly pigmented melanomas. The authors have now determined the ability of BPA to accumulate in several nonpigmented melanoma models including human melanoma xenografts in nude mice. The absolute amount of boron in the nonpigmented melanomas was about 50% of the observed in the pigmented counterparts but was still selectively concentrated in the tumor relative to normal tissues in amounts sufficient for effective neutron capture therapy. Single intragastric doses of BPA resulted in selective localization of boron in the amelanotic Greene melanoma carried in the anterior chamber of the rabbit eye and in a pigmented murine melanoma growing in the lungs. The ratio of the boron concentration in these tumors to the boron concentration in the immediately adjacent normal tissue was in the range of 3:1 to 4:1. These distribution studies support the proposal that boron neutron capture therapy may be useful as a regional therapy for malignant melanoma.

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

1990-01-01

382

Mass measurements of neutron rich isotopes in the Fe region and electron capture processes in neutron star crusts  

SciTech Connect

Experimental knowledge of nuclear masses of exotic nuclei is important for understanding nu- clear structure far from the valley of -stability, and as a direct input into astrophysical models. Electron capture processes in the crust of accreting neutron stars have been proposed as a heat source that can affect the thermal structure of the star. Nuclear masses of very neutron-rich nu- clides are necessary inputs to model the electron capture process. The time-of-flight (TOF) mass measurement technique allows measurements on very short-lived nuclei. It has been effectively applied using the fast fragment beams produced at the National Superconducting Cyclotron Lab (NSCL) to reach masses very far from stability. Measurements were performed for neutron-rich isotopes in the region of the N=32 and N=40 subshells, which coincides with the mass range of carbon superburst ashes. We discuss reaction network calculations performed to investigate the impact of our new measurements and to compare the effect of using different global mass models in the calculations. It is observed that the process is sensitive to the differences in the odd-even mass staggering predicted by the mass models, and our new result for 66Mn has a significant impact on the distribution of heat sources in the crust.

Estrade, Alfredo [National Superconducting Cyclotron Laboratory (NSCL); Matos, M. [Louisiana State University; Schatz, Hendrik [Michigan State University, East Lansing; Amthor, A. M. [National Superconducting Cyclotron Laboratory (NSCL); Beard, Mary [University of Notre Dame, IN; Brown, Edward [Michigan State University, East Lansing; Bazin, D. [National Superconducting Cyclotron Laboratory (NSCL); Becerril, A. [National Superconducting Cyclotron Laboratory (NSCL); Elliot, T [National Superconducting Cyclotron Laboratory (NSCL); Gade, A. [National Superconducting Cyclotron Laboratory (NSCL); Galaviz, D. [National Superconducting Cyclotron Laboratory (NSCL); Gupta, Sanjib [Indian Institute of Technology, Kanpur; Hix, William Raphael [ORNL; Lau, Rita [National Superconducting Cyclotron Laboratory (NSCL); Moeller, Peter [Los Alamos National Laboratory (LANL); Pereira, J. [National Superconducting Cyclotron Laboratory (NSCL); Portillo, M. [National Superconducting Cyclotron Laboratory (NSCL); Rogers, A. M. [National Superconducting Cyclotron Laboratory (NSCL); Shapira, Dan [ORNL; Smith, E. [Ohio State University; Stolz, A. [Michigan State University, East Lansing; Wallace, M. [Los Alamos National Laboratory (LANL); Wiescher, Michael [University of Notre Dame, IN

2010-01-01

383

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

SciTech Connect

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

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

2004-02-20

384

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

PubMed Central

Background Boron neutron capture reaction (BNCR) is based on irradiation of tumors after accumulation of boron compound. 10B captures neutrons and produces an alpha (4He) particle and a recoiled lithium nucleus (7Li). These particles have the characteristics of high linear energy transfer (LET) radiation and have marked biological effects. The purpose of this study is to verify that BNCR will increase cell killing and slow disappearance of repair protein-related foci to a greater extent in DNA repair-deficient cells than in wild-type cells. Methods Chinese hamster ovary (CHO-K1) cells and a DNA double-strand break (DSB) repair deficient mutant derivative, xrs-5 (Ku80 deficient CHO mutant cells), were irradiated by thermal neutrons. The quantity of DNA-DSBs following BNCR was evaluated by measuring the phosphorylation of histone protein H2AX (gamma-H2AX) and 53BP1 foci using immunofluorescence intensity. Results Two hours after neutron irradiation, the number of gamma-H2AX and 53BP1 foci in the CHO-K1 cells was decreased to 36.5-42.8% of the levels seen 30 min after irradiation. In contrast, two hours after irradiation, foci levels in the xrs-5 cells were 58.4-69.5% of those observed 30 min after irradiation. The number of gamma-H2AX foci in xrs-5 cells at 60-120 min after BNCT correlated with the cell killing effect of BNCR. However, in CHO-K1 cells, the RBE (relative biological effectiveness) estimated by the number of foci following BNCR was increased depending on the repair time and was not always correlated with the RBE of cytotoxicity. Conclusion Mutant xrs-5 cells show extreme sensitivity to ionizing radiation, because xrs-5 cells lack functional Ku-protein. Our results suggest that the DNA-DSBs induced by BNCR were not well repaired in the Ku80 deficient cells. The RBE following BNCR of radio-sensitive mutant cells was not increased but was lower than that of radio-resistant cells. These results suggest that gamma-ray resistant cells have an advantage over gamma-ray sensitive cells in BNCR.

2011-01-01

385

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

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

386

Measurement of the weak nucleon-nucleon interaction by polarized cold neutron capture on protons  

NASA Astrophysics Data System (ADS)

The NPDGamma Experiment at the Spallation Neutron Source at Oak Ridge National Laboratory is measuring the parity-odd correlation between the neutron spin and the direction of the emitted photon in the capture of polarized cold neutrons on protons. A parity violating asymmetry from this process is directly related to the strength of the hadronic weak interaction between nucleons. The experiment was run first with heavier nuclear targets to check systematic effects, false asymmetries, and backgrounds. Since early 2012 the experiment has been collecting data with a 16-liter liquid parahydrogen target. Data taking will continue through 2013 until statistics for a 10-8 asymmetry measurement are expected. The experiment performance will be discussed as well as the status of the asymmetry measurements.

Alarcon, R.; Blyth, D.

2014-03-01

387

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

SciTech Connect

Highlights of the Power Burst Facility Boron Neutron Capture Therapy (PBF/BNCT) Program during April 1990 include progress within the areas of: gross boron analysis in tissue, blood, and urine; analytical methodologies development for BSH (Borocaptate Sodium) purity determination; noninvasive boron quantitative determination; operator training was conducted and pharmacokinetic data obtained using a laboratory dog; dosimetry development continues on real-time neutron and gamma monitoring to provide treatment control capability; analytical radiation transport and interaction modeling for BNCT; large animal model studies; neutron source and facility preparation -- PBF upgrades, required for environmental, safety, and OSHA compliance, continue; administration and common support; and PBF operations -- training, safety, and preventive maintenance activities continue. 3 figs.

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

1990-04-01

388

Neutron Capture Isotopes in the Martian Regolith and Implications for Martian Atmospheric Noble Gases  

NASA Astrophysics Data System (ADS)

Impact-produced glasses in some martian meteorites have trapped significant amounts of the recent martian atmosphere. From literature data, we estimate that 9% of the trapped 80Kr in these meteorites was produced from neutron capture on 79Br. Estimates of neutron fluences made from 80Kr and 149Sm for bulk samples of meteorite EET79001 indicate that 80Kr excesses in the impact glass were not produced in situ. Theoretical calculations independently predict production of a large neutron-capture component of 80Kr and 36Ar in the martian regolith, and part of this component presumably escaped into the martian atmosphere. These calculations were made by using the Los Alamos High-Energy Transport Code to calculate the fluxes of galactic cosmic ray (GCR)-produced thermal neutrons as a function of depth in the uppermost 500 g cm -2 of the martian surface, and by adopting average Cl, Br, and I concentrations of the upper martian surface of 0.3%, 20 ppm, and 0.5 ppm, respectively. Combining these data with the appropriate neutron-capture cross sections, we calculate Mars global production rates of 80Kr n=2.410 16atoms sec -1, 36Ar n=5.510 18 atoms sec -1, and 128Xe n=310 13 atoms sec -1. Calculated global production rates of spallogenic 80Kr sp, and 36Ar sp, are smaller by factors of 770 and 29, respectively. It would require 330 Myr to produce an amount of 80Kr n equivalent to the amount inferred to be present today in the martian atmosphere (2.510 32 atoms). Production of these neutron-capture components probably has occurred over the past 4 Gyr, as only an atmospheric pressure substantially higher than today's would appreciably decrease the neutron flux in the regolith. Thus, most of the neutron-capture noble gases produced over time probably remain in the martian regolith and would make sensitive indicators of the time period a sample has resided near the martian surface. Assuming mixing of the martian surface to an average depth of 100 m, the predicted average regolith concentrations of 80Kr n, 36Ar n, and 128Xe n are 410 -9 cm -3 g -1, 110 -6 cm 3 g -1, and 510 -12 cm 3 g -1, respectively. If similar fractions of these neutron-capture isotopes have escaped into the atmosphere, they would comprise 3% and 0.2% of the present atmospheric inventories of 36Ar and 128Xe, respectively. The fractional excess of 80Kr n in ancient martian meteorite ALH84001 appears similar to that in shock-glass phases of young shergottite meteorites. If ALH84001 acquired its atmospheric gases 4 Gyr ago, this implies that, prior to that time, halogens were greatly concentrated at the martian surface by crustal formational and weathering processes, impacts efficiently degassed the regolith, and Mars did not have a significant atmosphere to shield the surface.

Rao, M. N.; Bogard, D. D.; Nyquist, L. E.; McKay, D. S.; Masarik, J.

2002-04-01

389

Angular correlations in emission of prescission neutrons from {sup 235}U fission induced by slow polarized neutrons  

SciTech Connect

A new approach to searching for and studying scission neutrons, which is based on the analysis of specific angular correlations in nuclear fission induced by polarized neutrons, is described and used to evaluate the fraction of scission neutrons in the total number of prompt neutrons of {sup 235}U fission emitted perpendicularly to the fission axis.

Danilyan, G. V., E-mail: danilyan@itep.r [Institute of Theoretical and Experimental Physics (Russian Federation); Wilpert, T.; Granz, P. [Hahn-Meitner Institute (Germany); Krakhotin, V. A. [Institute of Theoretical and Experimental Physics (Russian Federation); Mezei, F. [Hahn-Meitner Institute (Germany); Novitsky, V. V.; Pavlov, V. S. [Institute of Theoretical and Experimental Physics (Russian Federation); Russina, M. V. [Hahn-Meitner Institute (Germany); Shatalov, P. B. [Institute of Theoretical and Experimental Physics (Russian Federation)

2008-12-15

390

Effects of nuclear deformation and neutron transfer in capture processes, and fusion hindrance at deep 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 comparison of the calculated capture cross section and the measured fusion cross section in various reactions at extreme sub-barrier energies gives us information about the quasifission.

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

2011-12-01

391

Monte Carlo assessment of soil moisture effect on high-energy thermal neutron capture gamma-ray by 14N  

Microsoft Academic Search

Among many conventional techniques, nuclear techniques have shown to be faster, more reliable, and more effective in detecting explosives. In the present work, neutrons from a 5Ci AmBe neutron source being in water tank are captured by elements of soil and landmine (TNT), namely 14N, H, C, and O. The prompt capture gamma-ray spectrum taken by a NaI (Tl) scintillation

Ali Pazirandeh; Maryam Azizi; S. Farhad Masoudi

2006-01-01

392

Neutron capture cross section of C14 of astrophysical interest studied by Coulomb breakup of C15  

Microsoft Academic Search

The neutron capture reaction on C14 leading to the C15 ground state, which plays an important role in various nucleosynthesis processes, has been studied using the Coulomb breakup of C15 on a Pb target at 68 MeV\\/nucleon. The breakup cross section has been converted into the energy-dependent neutron capture cross section using the principle of detailed balance. The energy spectrum

T. Nakamura; N. Fukuda; N. Aoi; N. Imai; M. Ishihara; H. Iwasaki; T. Kobayashi; T. Kubo; A. Mengoni; T. Motobayashi; M. Notani; H. Otsu; H. Sakurai; S. Shimoura; T. Teranishi; Y. X. Watanabe; K. Yoneda

2009-01-01

393

Experimental imaging and profiling of absorbed dose in phantoms exposed to epithermal neutron beams for neutron capture therapy  

NASA Astrophysics Data System (ADS)

Absorbed-dose images and depth-dose profiles have been measured in a tissue-equivalent phantom exposed to an epithermal neutron beam designed for neutron capture therapy. The spatial distribution of absorbed dose has been measured by means of gel dosimeters, imaged with optical analysis. From differential measurements with gels having different isotopic composition, the contributions of all the components of the neutron field have been separated. This separation is important, owing to the different biological effectiveness of the various kinds of emitted radiation. The doses coming from the reactions 1H(n,?)2H and 14N(n,p)14C and the fast-neutron dose have been imaged. Moreover, a volume simulating a tumour with accumulation of 10B and/or 157Gd has been incorporated in the phantom and the doses due to the reactions with such isotopes have been imaged and profiled too. The results have been compared with those obtained with other experimental techniques and the agreement is very satisfactory.

Gambarini, G.; Colombi, C.

2003-08-01

394

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

SciTech Connect

Medical application of boron neutron capture therapy (BNCT) has been significantly hindered by the slow development of boron drug-targeting methodologies for the selective delivery of high boron concentration sto malignant cells. We have successfully sought to fill this need by creating liposomes suitable as in vivo boron delivery vehicles for BNCT. Delivery of therapeutic quantities of boron to tumors in murine models has been achieved with small unilamellar boron-rich liposomes. Subsequently, attempts have been made to improve delivery efficiency of liposomes encapsulating boron-containing water-soluble species into their hollow core by incorporating lipophilic boron compounds as addenda to the liposome bilayer, incorporating boron compounds as structural components of the bilayer (which however, poses the risk of sacrificing some stability), and combinations thereof. Regardless of the method, approximately 90% of the total liposome mass remains therapeutically inactive and comprised of the vehicle?s construction materials, while less than 5% is boron for neutron targeting. Following this laboratory's intensive study, the observed tumor specificity of certain liposomes has been attributed to their diminutive size of these liposomes (30-150 nm), which enables these small vesicles to pass through the porous, immature vasculature of rapidly growing tumor tissue. We surmised that any amphiphilic nanoparticle of suitable size could possess some tumor selectivity. Consequently, the discovery of a very boron-rich nanoparticle delivery agent with biodistribution performance similar to unilamellar liposomes became one of our goals. Closomers, a new class of polyhedral borane derivatives, attracted us as an alternative BNCT drug-delivery system. We specifically envisioned dodeca (nido-carboranyl)-substituted closomers as possibly having a great potential role in BNCT drug delivery. They could function as extraordinarily boron-rich BNCT drugs since they are amphiphilic unimolecular nanoparticles presenting several advantages: tunable size through functionalization and branching, spherical shape due to the icosahedral B122? core, promising water solubility resulting from degradation of all pendant closo-carborane groups to their hydrophilic nido anion substituents, and efficient boron delivery owing to the presence of 120 boron atoms which gives rise to a boron content as high as 40% by weight. Keeping the new objective in mind, we have focused on the design, synthesis and evaluation of new and very boron-rich closomer species. Additionally, progress has also been made toward the evaluation of a newly synthesized boron-rich lipid as a substitute for DSPC in bilayer construction, and the boron content of the resulting liposomes has been greatly enhanced. Related research involving the synthesis and self-assembly of carborane-containing amphiphiles has been systematically studied. Combined hydrophobic and hydrophilic properties of the single-chain amphiphiles allow their spontaneous self-assembly to form rods under a variety of variable conditions, such as concentration in the bilayer, carborane cage structure, chain-length, counterion identity, solvents, methods of preparation, and the ionic charge. On the other hand, the number of attached chains affects the self-assembly process. Particles having totally different shapes have been observed for dual-chain amphiphiles.

Professor M. Frederick Hawthorne

2005-04-07

395

Simultaneous measurement of neutron-induced capture and fission reactions at CERN  

NASA Astrophysics Data System (ADS)

The measurement of the capture cross-section of fissile elements, of utmost importance for the design of innovative nuclear reactors and the management of nuclear waste, faces particular difficulties related to the ? -ray background generated in the competing fission reactions. At the CERN neutron time-of-flight facility n_TOF we have combined the Total Absorption Calorimeter (TAC) capture detector with a set of three 235U loaded MicroMegas (MGAS) fission detectors for measuring simultaneously two reactions: capture and fission. The results presented here include the determination of the three detection efficiencies involved in the process: ensuremath \\varepsilon_{TAC}(n,f) , ensuremath \\varepsilon_{TAC}(n,?) and ensuremath \\varepsilon_{MGAS}(n,f) . In the test measurement we have succeeded in measuring simultaneously with a high total efficiency the 235U capture and fission cross-sections, disentangling accurately the two types of reactions. The work presented here proves that accurate capture cross-section measurements of fissile isotopes are feasible at n_TOF.

Guerrero, C.; Berthoumieux, E.; Cano-Ott, D.; Mendoza, E.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bcares, V.; Be?v?, F.; Belloni, F.; Billowes, J.; Brugger, M.; Calviani, M.; Calvio, F.; Carrapio, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Corts, G.; Corts-Giraldo, M. A.; Diakaki, M.; Dillmann, I.; Domingo-Pardo, C.; Duran, I.; Eleftheriadis, C.; Fernndez-Ordez, M.; Ferrari, A.; Ganesan, S.; Giubrone, G.; Gmez-Hornillos, M. B.; Gonalves, I. F.; Gonzlez-Romero, E.; Gramegna, F.; Griesmayer, E.; Gunsing, F.; Jenkins, D.; Jericha, E.; Kadi, Y.; Kppeler, F.; Karadimos, D.; Kroll, J.; Krti?ka, M.; Lebbos, E.; Lederer, C.; Leeb, H.; Losito, R.; Lozano, M.; Manousos, A.; Marganiec, J.; Marrone, S.; Martinez, T.; Massimi, C.; Mastinu, P. F.; Meaze, M.; Mengoni, A.; Milazzo, P. M.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plag, R.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Roman, F.; Rubbia, C.; Sarmento, R.; Tagliente, G.; Tain, J. L.; Tarro, D.; Tassan-Got, L.; Tsinganis, A.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vermeullen, M.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Wei, C.; Wright, T.

2012-03-01

396

Inhibition of human pancreatic cancer growth in nude mice by boron neutron capture therapy.  

PubMed Central

Immunoliposomes were prepared by conjugating anti-carcinoembryonic antigen (CEA) monoclonal antibody with liposomes containing [10B]compound. These immunoliposomes were shown to bind selectively to human pancreatic carcinoma cells (AsPC-1) bearing CEA on their surface. The cytotoxic effects of locally injected [10B]compound, multilamellar liposomes containing [10B]compound or [10B]immunoliposomes (anti-CEA) on human pancreatic carcinoma xenografts in nude mice were evaluated with thermal neutron irradiation. After thermal neutron irradiation of mice injected with [10B]solution, 10B-containing liposomes or [10B]immunoliposomes, AsPC-1 tumour growth was suppressed relative to controls. Injection of [10B]immunoliposomes caused the greatest tumour suppression with thermal neutron irradiation in vivo. Histopathologically, hyalinization and necrosis were found in 10B-treated tumours, while tumour tissue injected with saline or saline-containing immunoliposomes showed neither destruction nor necrosis. These results suggest that intratumoral injection of boronated immunoliposomes can increase the retention of 10B atoms by tumour cells, causing tumour growth suppression in vivo upon thermal neutron irradiation. Boron neutron capture therapy (BNCT) with intratumoral injection of immunoliposomes is able to destroy malignant cells in the marginal portion between normal tissues and cancer tissues from the side of 4He generation. Images Figure 2

Yanagie, H.; Tomita, T.; Kobayashi, H.; Fujii, Y.; Nonaka, Y.; Saegusa, Y.; Hasumi, K.; Eriguchi, M.; Kobayashi, T.; Ono, K.

1997-01-01

397

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

PubMed

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

Moss, R L

1990-01-01

398

Neutron-induced capture cross sections via the surrogate reaction method  

NASA Astrophysics Data System (ADS)

The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. In this method, the compound nucleus is produced via an alternative (surrogate) reaction and its decay (by fission, gamma or neutron emission) is measured in coincidence with the outgoing appropriate charged particle. This technique has enabled neutron-induced cross sections to be extracted for nuclear reactions on short-lived nuclei that otherwise could not be measured. The CENBG collaboration has successfully applied this technique to determine the neutron-induced fission cross sections of several short-lived nuclei such as 233Pa, 242,243Cm and 241Am. These data are very important for the development of the Th/U cycle and for minor actinide transmutation. We currently investigate whether this powerful technique can also be used to determine the neutron-induced capture cross sections. For this purpose we will use the surrogate reaction 174Yb(3He,p?)176Lu to infer the well known 175Lu(n,?) cross section and compare the results with the directly measured neutron-induced data. The experimental set-up and the first results will be presented. We will also discuss our future plans to use the surrogate method for extracting actinides (n,?) cross sections.

Ache, M.; Boutoux, G.; Jurado, B.; Barreau, G.; Capellan, N.; Companis, I.; Czajkowski, S.; Dassi, D.; Haas, B.; Mathieu, L.; Bail, A.; Bauge, E.; Daugas, J. M.; Faul, T.; Gaudefroy, L.; Mot, V.; Morel, P.; Pillet, N.; Roig, O.; Taieb, J.; Throine, C.; Srot, O.; Gunsing, F.; Burke, J. T.; Derkx, X.; Tassan-Got, L.

2010-10-01

399

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

SciTech Connect

A segmented neutron calorimeter using nine 4-inch x 4-inch x 48-inch plastic scintillators and sixteen 2-inch-diameter 48-inch-long 200-mbar-{sup 3}He drift tubes is described. The correlated scintillator and neutron-capture events provide a means for n/{gamma} discrimination, critical to the neutron calorimetry when the {gamma} background is substantial and the {gamma} signals are comparable in amplitude to the neutron signals. A single-cell prototype was constructed and tested. It can distinguish between a {sup 17}N source and a {sup 252}Cf source when the {gamma} and the thermal neutron background are sufficiently small. The design and construction of the nine-cell segmented detector assembly follow the same principle. By recording the signals from individual scintillators, additional {gamma}-subtraction schemes, such as through the time-of-flight between two scintillators, may also be used. The variations of the light outputs from different parts of a scintillator bar are less than 10%.

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

2010-01-01

400

Isotopic Identification of Neutron Resonances of Cd, Sb, Os, and Pt from Capture Gamma-Ray Spectra  

Microsoft Academic Search

The Argonne fast chopper has been used in conjunction with a 3-variable magnetic-tape recording system to demonstrate the high efficiency and sensitivity of isotopic identification of neutron resonances by observation of capture gamma rays. A discussion of features of capture spectra which can be useful in isotopic assignment is presented as well as results for resonances in natural Cd, Sb,

H. E. Jackson; L. M. Bollinger

1961-01-01

401

Evidence for Significant Target Outer-Shell Excitation in Multiple-Electron Capture Collisions of Slow Highly Charged Ions with Many-Electron Atoms  

SciTech Connect

Unequivocal evidence for significant target outer-shell excitation accompanying multiple-electron capture, in slow collisions of highly charged ions with many-electron atoms, has been obtained by means of simultaneous Auger-electron and cold-target recoil-ion momentum spectroscopic measurements. For the 28 keV {sup 15}N{sup 7+}+Ar collision system, it is found that target excitation accompanies about 40% of all double-electron capture collisions. The evidence supports the predictions of the molecular classical overbarrier model by Niehaus [A. Niehaus, J. Phys. B 19, 2925 (1986)]. (c) 1999 The American Physical Society.

Hasan, A. A.; Emmons, E. D.; Hinojosa, G.; Ali, R.

1999-11-29

402

Neutron capture in (sup 122,123,124)Te: A critical test for s-process studies.  

National Technical Information Service (NTIS)

The neutron capture cross sections of (sup 122,123,124,125,126)Te were measured in the energy range from 10 to 200 keV at the Karlsruhe Van de Graaff accelerator using gold as a standard. Neutrons were produced via the (sup 7)Li(p,n)(sup 7)Be reaction by ...

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

1991-01-01

403

Photodisintegration of 80Se, 94Zr, and 108Pd as a probe of neutron capture for radioactive nuclei  

NASA Astrophysics Data System (ADS)

Photoneutron cross sections were measured for 80 Se near the neutron separation energy with the laser Compton scattering ? rays. The stellar neutron capture rate for 79 Se was evaluated by using the photodisintegration data as constraints on the E1 ? strength function within the framework of the Hauser-Feshbach statistical model. The result is compared with the model calculation of Bao and Kppeler.

Utsunomiya, Hiroaki; Utsunomiya, H.; Goko, S.; Kaihori, T.; Akimune, H.; Yamagaya, T.; Hohara, S.; Goriely, S.; Toyokawa, H.; Harano, H.; Matsumono, T.; Harada, H.; Kitatani, F.; Hara, K. Y.; Lui, Y.-W.

404

New Atomic Data for Neutron-Capture Elements and Their Application to Abundance Determinations in Ionized Nebulae  

Microsoft Academic Search

The detection of neutron(n)-capture elements (atomic number Z>30) in the spectra of nearly 100 planetary nebulae (PNe; Sterling & Dinerstein 2008, ApJS, 174, 157) demonstrates that nebular spectroscopy is a potentially powerful new tool to investigate n-capture nucleosynthesis and the chemical evolution of trans-iron elements in the Universe. Nebular spectroscopy provides access to several n-capture elements that are not detectable

Nicholas C. Sterling; M. C. Witthoeft; D. A. Esteves; R. C. Bilodeau; E. C. Red; A. L. D. Kilcoyne; R. A. Phaneuf; G. Alna'Washi; A. Aguilar

2011-01-01

405

Fast neutron capture on the Hf isotopes: Cross sections, isomer production, and stellar aspects  

SciTech Connect

The (n,{gamma}) cross sections of {sup 176}Hf, {sup 177}Hf, {sup 178}Hf, {sup 179}Hf, and {sup 180}Hf have been measured in the energy range from 3 to 225 keV relative to the gold standard. Neutrons were produced via the {sup 7}Li(p,n){sup 7}Be reaction and capture events were registered with the Karlsruhe 4{pi} barium fluoride detector. The overall uncertainties are between 0.9 and 2.6%, about 5 times smaller than in previous experiments. Partial cross sections to ground and isomeric states could be experimentally identified for neutron capture on {sup 176,177,178,179}Hf, indicating a strong population of yet-unknown isomeric states in {sup 177}Hf and {sup 180}Hf. This feature was confirmed by extensive GEANT simulations based on calculated capture cascades. The deduced Maxwellian-averaged (n,{gamma}) cross sections for thermal energies between kT=8 and 100 keV contribute to the analysis of the s-process branchings at A=176 and A=179/180 and have significant consequences for the separation of the solar s- and r-process components.

Wisshak, K.; Voss, F.; Kaeppeler, F.; Kazakov, L.; Becvar, F.; Krticka, M.; Gallino, R.; Pignatari, M. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640 D-76021 Karlsruhe (Germany); Institute for Physics and Power Engineering, Obninsk, Kaluga-Region (Russian Federation); Faculty of Mathematics and Physics, Charles University, CZ-180 00 Prague (Czech Republic); Dipartimento di Fisica Generale, Universita di Torino and Sezione INFN di Torino, Via P. Giuria 1, I-10125 Turin (Italy) and Centre for Stellar and Planetary Astrophysics, Monash University, Victoria 3800 (Australia); Dipartimento di Fisica Generale, Universita di Torino and Sezione INFN di Torino, Via P. Giuria 1, I-10125 Turin (Italy)

2006-04-15

406

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

NASA Astrophysics Data System (ADS)

Neutron-based inspection techniques are unique in their ability to provide material specific signatures, thus offering very high performance and automatic detection of explosives and other contraband. Thermal neutron capture gamma spectroscopy provides excellent sensitivities to hydrogen, nitrogen, chlorine, and other elements, which are characteristic to most explosives, drugs and other contraband that may be smuggled into the country. Fast neutron gamma production (mostly through inelastic scattering) provides good sensitivity to carbon and oxygen. When necessary, these two types of complementary interactions can be combined to yield a more accurate material determination inside small to medium size containers. Standard pulsed 14 MeV electronic neutron generators offer an efficient way to obtain these two types of interactions. Fast (14 MeV) neutrons are produced during the pulse. After the pulse, only the decaying thermal neutron population exists, and thus pure neutron capture gamma-rays are produced. Unfortunately, during the pulse (which is normally much longer than the neutron thermalization time) the fast neutron interactions are highly "contaminated" by the interactions of thermal neutrons within the object and the nearby gamma-ray detectors. This creates high background and spectral interferences in the common medium resolution detectors, such as NaI, BGO, etc. The use of an appropriate shielding, neutron spectrum tailoring, full spectral feature analysis as well as temporal information ("die-away" time) resulted in significant performance enhancements in detection of explosives, drugs and other contraband in difficult geometries.

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

2003-06-01

407

A Nuclear Data Project on Neutron Capture Cross Sections of Long-Lived Fission Products and Minor Actinides  

NASA Astrophysics Data System (ADS)

A nuclear data project entitled "Systematic Study on Neutron Capture Reaction Cross Sections for the Technological Development of Nuclear Transmutation of Long-Lived Nuclear Wastes" is being performed. The objective of the project is to improve nuclear data libraries, by making the precise measurements of neutron capture cross sections of Long-Lived Nuclear Wastes (LLNWs), analyzing the measured results theoretically, and supplying reliable calculated capture cross sections for the LLNWs. This contribution presents the outline of the project, and individual results are presented by other contributions.

Igashira, M.; Katabuchi, T.; Harada, H.; Nakamura, S.; Kimura, A.; Iwamoto, N.; Hori, J.; Kiyanagi, Y.

2014-04-01

408

Gamma rays from 27. 7-keV s-wave neutron resonance capture by /sup 56/Fe  

SciTech Connect

We have measured distinguishable gamma rays for the transition to the ground state and to the first excited state following 27.7-keV s-wave neutron resonance capture by /sup 56/Fe with a good signal-to-noise ratio, using a 60-cm/sup 3/ pure Ge detector. Partial radiation widths have been obtained for both transitions. It has been found that those widths are not comprehensible in the valency capture model. The results suggest that there is some possibility of core excitation in s-wave neutron resonance capture by /sup 56/Fe.

Komano, H.; Igashira, M.; Shimizu, M.; Kitazawa, H.

1984-01-01

409

On the use of gamma rays from inelastic scattering for the measurement of neutron slowing-down times in the sub-microsecond region  

NASA Astrophysics Data System (ADS)

Studies are made which demonstrate that inelastic neutron scattering, (n, n' ?), in a suitable isotope can provide the basis for an indicator for fast neutron slowing-down time measurements in the sub-microsecond region. Observation of the time-dependent reaction rates of the emitted gamma rays from the excited states in the indicator allows the slowing-down times to be defined. The competing effects of different levels and the effects of level lifetimes are considered. Numerical examples are provided for neutron slowing down to 110 keV in natural iron using 19F as an indicator.

Beynon, T. D.; Walker, J.

1974-05-01

410

Boron containing macromolecules and nanovehicles as delivery agents for neutron capture therapy.  

PubMed

Boron neutron capture therapy (BNCT) is based on the nuclear capture and fission reactions that occur when non-radioactive boron-10 is irradiated with low energy thermal neutrons to yield high linear energy transfer (LET) alpha particles ((4)He) and recoiling lithium -7((7)Li) nuclei. For BNCT to be successful, a sufficient number of (10)B atoms ( approximately 10(9) atoms/cell) must be selectively delivered to the tumor and enough thermal neutrons must be absorbed by them to sustain a lethal (10)B(n, alpha) (7)Li capture reaction. BNCT primarily has been used to treat patients with brain tumors, and more recently those with head and neck cancer. Two low molecular weight (LMW) boron delivery agents currently are being used clinically, sodium borocaptate and boronophenylalanine. However, a variety of high molecular weight (HMW) agents consisting of macromolecules and nanovehicles have been developed. This review will focus on the latter which include: monoclonal antibodies, dendrimers, liposomes, dextrans, polylysine, avidin, folic acid, and epidermal and vascular endothelial growth factors (EGF and VEGF). Procedures for introducing boron atoms into these HMW agents and their chemical properties will be discussed. In vivo studies on their biodistribution will be described, and the efficacy of a subset of them, which have been used for BNCT of tumors in experimental animals, will be discussed. Since brain tumors currently are the primary candidates for treatment by BNCT, delivery of these HMW agents across the blood-brain barrier presents a special challenge. Various routes of administration will be discussed including receptor-facilitated transcytosis following intravenous administration, direct intratumoral injection and convection enhanced delivery by which a pump is used to apply a pressure gradient to establish bulk flow of the HMW agent during interstitial infusion. Finally, we will conclude with a discussion relating to issues that must be addressed if these HMW agents are to be used clinically. PMID:16529539

Wu, Gong; Barth, Rolf F; Yang, Weilian; Lee, Robert J; Tjarks, Werner; Backer, Marina V; Backer, Joseph M

2006-03-01

411

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

SciTech Connect

The {sup 75}As(d,p{gamma}) reaction in inverse kinematics as a surrogate for neutron capture was performed at Oak Ridge National Laboratory using a deuterated plastic target. The intensity of the 165 keV {gamma}-ray from {sup 76}As in coincidence with ejected protons, from exciting {sup 76}As above the neutron separation energy populating a compound state, was measured. A tight geometry of four segmented germanium clover {gamma}-ray detectors together with eight ORRUBA-type silicon-strip charged-particle detectors was used to optimize geometric acceptance. The preliminary analysis of the {sup 75}As experiment, and the efficacy and future plans of the (d,p{gamma}) surrogate campaign in inverse kinematics, are discussed.

Peters, W A; Cizewski, J A; Hatarik, R; O?Malley, P D; Jones, K L; Schmitt, K; Moazen, B H; Chae, K Y; Pittman, S T; Kozub, R L; Vieira, D; Jandel, M; Wilhelmy, J B; Matei, C; Escher, J; Bardayan, D W; Pain, S D; Smith, M S

2009-11-09

412

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

NASA Astrophysics Data System (ADS)

Boron Neutron Capture Therapy (BNCT) is a cancer therapy by utilizing thermal neutron to produce alpha particles and lithium nuclei. The superiority of BNCT is that the radiation effects could be limited only for the tumor cells. BNCT radiation dose depends on the distribution of boron in the tumor. Absorbed dose to the cells from the reaction 10B (n, ?) 7Li was calculated near interface medium containing boron and boron-free region. The method considers the contribution of the alpha particle and recoiled lithium particle to the absorbed dose and the variation of Linear Energy Transfer (LET) charged particles energy. Geometrical factor data of boron distribution for the spherical surface is used to calculate the energy absorbed in the tumor cells, brain and scalp for case Glioblastoma Multiforme. The result shows that the optimal dose in tumor is obtained for boron concentrations of 22.1 mg 10B/g blood.

Zasneda, Sabriani; Widita, Rena

2010-06-01

413

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

SciTech Connect

Boron Neutron Capture Therapy (BNCT) is a cancer therapy by utilizing thermal neutron to produce alpha particles and lithium nuclei. The superiority of BNCT is that the radiation effects could be limited only for the tumor cells. BNCT radiation dose depends on the distribution of boron in the tumor. Absorbed dose to the cells from the reaction 10B (n, {alpha}) 7Li was calculated near interface medium containing boron and boron-free region. The method considers the contribution of the alpha particle and recoiled lithium particle to the absorbed dose and the variation of Linear Energy Transfer (LET) charged particles energy. Geometrical factor data of boron distribution for the spherical surface is used to calculate the energy absorbed in the tumor cells, brain and scalp for case Glioblastoma Multiforme. The result shows that the optimal dose in tumor is obtained for boron concentrations of 22.1 mg {sup 10}B/g blood.

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

2010-06-22

414

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

NASA Astrophysics Data System (ADS)

The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has been optimizing high surface area activated carbon nanospaces for high capacity hydrogen storage. Boron doped samples have been prepared by vapor deposition of decaborane. Neutron irradiation of Boron doped activated carbon was done at the University of Missouri Research Reactor (MURR). Ultrananopores created by alpha particle fission tracks from Boron-neutron capture alter the surface and the adsorption properties of activated Carbons. A detailed theoretical model of the creation and the structure of defects on graphene sheets was developed. BET surface areas, porosity, and pores size distributions of modified activated carbons were measured using sub-critical nitrogen isotherms. Hydrogen adsorption isotherms of irradiated samples were indicative of record fraction of high binding energies and record fraction of sub-nm pores compared to their unirradiated parent samples.

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

2010-03-01

415

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

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of the radioactive isotope Hf182 (t1/2=8.9106 yr) in the thermal and epithermal energy regions have been measured by activation at the TRIGA Mark-II reactor of the Atomic Institute of the Austrian Universities in Vienna, Austria, and subsequent ?-ray spectroscopy of Hf183. High values for the thermal (kT=25 meV) cross section ?0=13310 b and for the resonance integral I0=5850660 b were found. Additionally, the absolute intensities of the main ?-ray transitions in the decay of Hf182 have been considerably improved.

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

2008-04-01

416

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

PubMed

We have already synthesized a boron-containing polymeric micellar drug delivery system for boron neutron capture therapy (BNCT). The synthesized diblock copolymer, boron-terminated copolymers (Bpin-PLA-PEOz), consisted of biodegradable poly(D,l-lactide) (PLA) block and water-soluble polyelectrolyte poly(2-ethyl-2-oxazoline) (PEOz) block, and a cap of pinacol boronate ester (Bpin). In this study, we have demonstrated that synthesized Bpin-PLA-PEOz micelle has great potential to be boron drug delivery system with preliminary evaluation of biocompatibility and boron content. PMID:24447933

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

2014-06-01

417

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

PubMed

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

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

2014-06-01

418

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

PubMed

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

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

2014-06-01

419

Measurement of cross sections for 14 MeV neutron capture  

Microsoft Academic Search

Activation cross sections for neutron capture have been measured at an energy of 14.6 +\\/- 0.2 MeV relative to sigma(27Al(n,alpha)24Na) = 114.2 mb +\\/- 1.2% for the nuclei 37Cl, 14K, 50Ti, 51V, 55Mn, 71Ga, 87Rb, 89Y, 127I, 130Te, 138Ba, 139La, 142Ce, 186W, 198Pt,197Au. Gamma-ray spectra of the product nuclei were measured with a Ge(Li) detector. Special attention was paid to

O. Schwerer; M. Winkler-Rohatsch; H. Warhanek; G. Winkler

1976-01-01

420

Neutron capture cross sections of {sup 148}Gd and the decay of {sup 149}Gd  

SciTech Connect

The thermal cross section and resonance integral were measured for radiative neutron capture by radioactive {sup 148}Gd. The deduced values are {sigma}=9600{+-}900 b and I=28,200{+-}2300. We also deduced upper limits for the n,p and n, {alpha} cross sections, respectively, 0.25 b and 13 b. The {gamma}-ray spectrum from the decay of {sup 149}Gd was studied in singles mode at high resolution to verify the previously determined energies and intensities. From the latter measurements, new transitions are proposed and upper limits are deduced for previously reported transitions.

Rios, M. G.; Casperson, R. J.; Krane, K. S. [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States); Norman, E. B. [Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

2006-10-15

421

Response of rat skin to boron neutron capture therapy with p-boronophenylalanine or borocaptate sodium.  

PubMed

The effects of boron neutron capture irradiation employing either BPA or BSH as neutron capture agents has been assessed using the dorsal skin of Fischer 344 rats. Pharmacokinetic studies, using prompt gamma spectrometry, revealed comparable levels of boron-10 (10B) in blood and skin after the intravenous infusion of BSH (100 mg/kg body wt.). The 10B content of blood (12.0 +/- 0.5 micrograms/g) was slightly higher than that of skin (10.0 +/- 0.5 micrograms/g) after oral dosing with BPA. Biphasic skin reactions were observed after irradiation with the thermal neutron beam alone or in combination with BPA or BSH. The time of onset of the first phase of the skin reaction, moist desquamation, was approximately 2 weeks. The time at which the second-wave skin reaction, dermal necrosis, became evident was dose-related and occurred after a latent interval of > or = 24 weeks, well after the acute epithelial reaction had healed. The incidence of both phases of skin damage was also dose-related. The radiation doses required to produce skin damage in 50% of skin sites (ED50 values) were calculated from dose-effect curves and these values were used to determine relative biological effectiveness (RBE) and compound biological effectiveness (CBE) factors for both moist desquamation and dermal necrosis. It was concluded on the basis of these calculations that the microdistribution of the two neutron capture agents had a critical bearing on the overall biological effect after thermal neutron activation. BSH, which was possibly excluded from the cytoplasm of epidermal cells, had a low CBE factor value (0.56 +/- 0.06) while BPA, which may be selectively accumulated in epidermal cells had a very high CBE factor (3.74 +/- 0.7). For the dermal reaction, where vascular endothelial cells represent the likely target cell population, the CBE factor values were comparable, at 0.73 +/- 0.42 and 0.86 +/- 0.08 for BPA ad BSH, respectively. PMID:7972908

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

1994-08-01

422

Development of a high-power neutron-producing lithium target for boron neutron capture therapy  

Microsoft Academic Search

A neutron producing lithium target for a novel, accelerator based cancer treatment requires the removal of up to 6kW of heat produced by 1-2mA beam of 2.3-3.0MeV protons. This paper presents the results form computer simulations which show that, using submerged jet cooling, a solid lithium target can be maintained up to 1.6mA, and a liquid target up to 2.6mA,

Adam V. Brown; Malcolm C. Scott

2000-01-01

423

Controllability of depth dose distribution for neutron capture therapy at the Heavy Water Neutron Irradiation Facility of Kyoto University Research Reactor.  

PubMed

The updating construction of the Heavy Water Neutron Irradiation Facility of the Kyoto University Research Reactor has been performed from November 1995 to March 1996 mainly for the improvement in neutron capture therapy. On the performance, the neutron irradiation modes with the variable energy spectra from almost pure thermal to epi-thermal neutrons became available by the control of the heavy-water thickness in the spectrum shifter and by the open-and-close of the cadmium and boral thermal neutron filters. The depth distributions of thermal, epi-thermal and fast neutron fluxes were measured by activation method using gold and indium, and the depth distributions of gamma-ray absorbed dose rate were measured using thermo-luminescent dosimeter of beryllium oxide for the several irradiation modes. From these measured data, the controllability of the depth dose distribution using the spectrum shifter and the thermal neutron filters was confirmed. PMID:12408308

Sakurai, Yoshinori; Kobayashi, Tooru

2002-10-01

424

Experimental assessment of the performance of a proposed lead slowing-down spectrometer at WNR/PSR (Weapons Neutron Research/Proton Storage Ring)  

SciTech Connect

In November 1989, we carried out a measurement of the fission cross section of {sup 247}Cm, {sup 250}Cf, and {sup 254}Es on the Rensselaer Intense Neutron Source (RINS) at Rensselaer Polytechnic Institute (RPI). In July 1990, we carried out a second measurement, using the same fission chamber and electronics, in beam geometry at the Los Alamos Neutron Scattering Center (LANSCE) facility. Using the relative count rates observed in the two experiments, and the flux-enhancement factors determined by the RPI group for a lead slowing-down spectrometer compared to beam geometry, we can assess the performance of a spectrometer similar to RINS, driven by the Proton Storage Ring (PSR) at the Los Alamos National Laboratory. With such a spectrometer, we find that is is feasible to make measurements with samples of 1 ng for fission 1 {mu}g for capture, and of isotopes with half-lives of tens of minutes. It is important to note that, while a significant amount of information can be obtained from the low resolution RINS measurement, a definitive determination of average properties, including the level density, requires that the resonance structure be resolved. 12 refs., 5 figs., 3 tabs.

Moore, M.S.; Koehler, P.E.; Michaudon, A.; Schelberg, A. (Los Alamos National Lab., NM (USA)); Danon, Y.; Block, R.C.; Slovacek, R.E. (Rensselaer Polytechnic Inst., Troy, NY (USA)); Hoff, R.W.; Lougheed, R.W. (Lawrence Livermore National Lab., CA (USA))

1990-01-01

425

Development of a high-power neutron-producing lithium target for boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

A neutron producing lithium target for a novel, accelerator based cancer treatment requires the removal of up to 6kW of heat produced by 1-2mA beam of 2.3-3.0MeV protons. This paper presents the results form computer simulations which show that, using submerged jet cooling, a solid lithium target can be maintained up to 1.6mA, and a liquid target up to 2.6mA, assuming a 3.0MeV proton beam. The predictions from the simulations are verified through the use of an experimental heat transfer test-rig and the result form a number of metallurgical studies made to select a compatible substrate material for the lithium are reported.

Brown, Adam V.; Scott, Malcolm C.

2000-12-01

426

Homogeneous immunoconjugates for boron neutron-capture therapy: design, synthesis, and preliminary characterization.  

PubMed

The application of immunoprotein-based targeting strategies to the boron neutron-capture therapy of cancer poses an exceptional challenge, because viable boron neutron-capture therapy by this method will require the efficient delivery of 10(3) boron-10 atoms by each antigen-binding protein. Our recent investigations in this area have been focused on the development of efficient methods for the assembly of homogeneous immunoprotein conjugates containing the requisite boron load. In this regard, engineered immunoproteins fitted with unique, exposed cysteine residues provide attractive vehicles for site-specific modification. Additionally, homogeneous oligomeric boron-rich phosphodiesters (oligophosphates) have been identified as promising conjugation reagents. The coupling of two such boron-rich oligophosphates to sulfhydryls introduced to the CH2 domain of a chimeric IgG3 has been demonstrated. The resulting boron-rich immunoconjugates are formed efficiently, are readily purified, and have promising in vitro and in vivo characteristics. Encouragingly, these studies showed subtle differences in the properties of the conjugates derived from the two oligophosphate molecules studied, providing a basis for the application of rational design to future work. Such subtle details would not have been as readily discernible in heterogeneous conjugates, thus validating the rigorous experimental design employed here. PMID:9789066

Guan, L; Wims, L A; Kane, R R; Smuckler, M B; Morrison, S L; Hawthorne, M F

1998-10-27

427

Homogeneous immunoconjugates for boron neutron-capture therapy: Design, synthesis, and preliminary characterization  

PubMed Central

The application of immunoprotein-based targeting strategies to the boron neutron-capture therapy of cancer poses an exceptional challenge, because viable boron neutron-capture therapy by this method will require the efficient delivery of 103 boron-10 atoms by each antigen-binding protein. Our recent investigations in this area have been focused on the development of efficient methods for the assembly of homogeneous immunoprotein conjugates containing the requisite boron load. In this regard, engineered immunoproteins fitted with unique, exposed cysteine residues provide attractive vehicles for site-specific modification. Additionally, homogeneous oligomeric boron-rich phosphodiesters (oligophosphates) have been identified as promising conjugation reagents. The coupling of two such boron-rich oligophosphates to sulfhydryls introduced to the CH2 domain of a chimeric IgG3 has been demonstrated. The resulting boron-rich immunoconjugates are formed efficiently, are readily purified, and have promising in vitro and in vivo characteristics. Encouragingly, these studies showed subtle differences in the properties of the conjugates derived from the two oligophosphate molecules studied, providing a basis for the application of rational design to future work. Such subtle details would not have been as readily discernible in heterogeneous conjugates, thus validating the rigorous experimental design employed here.

Guan, Lufeng; Wims, Letitia A.; Kane, Robert R.; Smuckler, Mark B.; Morrison, Sherie L.; Hawthorne, M. Frederick

1998-01-01

428

Responses of total and quiescent cell populations in solid tumors to boron and gadolinium neutron capture reaction using neutrons with two different energy spectra.  

PubMed

In neutron capture therapy, whose effectiveness depends on the tumor distribution of neutron capture compound and the neutron energy distribution, controlling quiescent tumor cells with clonogenic potential is critical for therapeutic gain, as is the case in conventional radio- and chemotherapy. Tumor-bearing mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all proliferating cells. After administration of sodium borocaptate-10B (BSH), dl-p-boronophenylalanine-10B (BPA) or gadodiamide hydrate (Omniscan), the tumors were irradiated with neutrons of different cadmium (Cd) ratio, and then isolated and incubated with cytochalasin-B (a cytokinesis blocker). The micronucleus (MN) frequency in cells without BrdU labeling (quiescent cells) was determined using immunofluorescence staining for BrdU, and that for total cells was obtained from tumors not pretreated with BrdU. Without drugs, quiescent cells showed lower MN frequencies than total cells, but neutron irradiation reduced gamma-ray sensitivity difference between the two. Relative biological effectiveness (RBE) of neutrons compared with gamma-rays was greater in quiescent cells than in total cells, and low Cd ratio neutrons tended to exhibit large RBE values. With neutron capture compounds, MN frequency for each cell population was increased, especially when high Cd ratio neutrons were used. BPA increased the MN frequency for total cells to a greater extent than BSH. However, the sensitivity of quiescent cells treated with BPA was lower than that in BSH-treated quiescent cells. This tendency was clearly observed in high Cd ratio neutrons. Omniscan only slightly increased the MN frequency in both cell populations, compared with irradiation alone, without drugs. From the viewpoint of increasing the quiescent cell sensitivity, tumors should be irradiated with high Cd ratio neutrons after BSH administration. PMID:9510480

Masunaga, S; Ono, K; Sakurai, Y; Suzuki, M; Takagaki, M; Kobayashi, T; Kinashi, Y; Akaboshi, M

1998-01-01

429

Neutron-capture Cl-36, Ca-41, Ar-36, and Sm-150 in large chondrites: Evidence for high fluences of thermalized neutrons  

NASA Technical Reports Server (NTRS)

We have measured significant concentrations of Cl-36, Ca-41, Ar-36 from decay of Cl-36, and Sm-150 produced from the capture of thermalized neutrons in the large Chico L6 chondrite. Activities of Cl-36 and Ca-41, corrected for a high-energy spallogenic component and a terrestrial age of approximately 50 ka, give average neutron-capture production rates of 208 atoms/min/g-Cl and 1525 atoms/min/kg-Ca, which correspond to thermal neutron (n) fluxes of 6.2 n/sq cm/s and 4.3 n/sq cm/s, respectively. If sustained for the approximately 65 Ma single-stage, cosmic ray exposure age of Chico, these values correspond to thermal neutron fluences of approximately 1.3 x 10(exp 16) and 0.8 x 10(exp 16) n/sq cm for Cl-36 and Ca-41, respectively. Stepwise temperature extraction of Ar in Chico impact melt shows Ar-36/Ar-38 ratios as large as approximately 9. The correlation of high Ar-36/Ar-38 with high Cl/Ca phases in neutron-irradiated Chico indicates that the excess Ar-36 above that expected from spallation is due to decay of neutron-produced Cl-36. Excess Ar-36 in Chico requires a thermal neutron fluence of 0.9-1.7 x 10(exp 16) n/sq cm. Decreases in Sm-149/Sm-152 due to neutron-capture by Sm-149 correlate with increases in Sm-150/Sm-152 for three samples of Chico, and one of the Torino H-chondrite. The 0.08% decrease in Sm-149 shown by Chico corresponds to a neutron fluence of 1.23 x 10(exp 16) n/sq cm. This fluence derived from Sm considers capture of epithermal neutrons and effects of chemical composition on the neutron energy distribution. Excess Ar-36 identified in the Arapahoe, Bruderheim, and Torino chondrites and the Shallowater aubrite suggest exposure to neutron fluences of approximately 0.2-0.2 x 10(exp 16) n/sq cm. Depletion of Sm-149 in Torino and the LEW86010 angrite suggest neutron fluences of 0.8 x 10(exp 16) n/sq cm and 0.25 x 10(exp 16) n/sq cm, respectively. Neutron fluences of approximately 10(exp 16) n/sq cm in Chico are almost as large as those previously observed for some lunar soils. Consideration of exposure ages suggests that the neutron flux in Chico may have been greater than that in many lunar soils.

Bogard, D. D.; Nyquist, L. E.; Bansal, B. M.; Garrison, D. H.; Wiesmann, H.; Herzog, G. F.; Albrecht, A. A.; Vogt, S.; Klein, J.

1995-01-01

430

Monte Carlo simulation of depth dose distribution in several organic models for boron neutron capture therapy  

NASA Astrophysics Data System (ADS)

Monte Carlo simulations are performed to evaluate depth-dose distributions for possible treatment of cancers by boron neutron capture therapy (BNCT). The ICRU computational model of ADAM & EVA was used as a phantom to simulate tumors at a depth of 5 cm in central regions of the lungs, liver and pancreas. Tumors of the prostate and osteosarcoma were also centered at the depth of 4.5 and 2.5 cm in the phantom models. The epithermal neutron beam from a research reactor was the primary neutron source for the MCNP calculation of the depth-dose distributions in those cancer models. For brain tumor irradiations, the whole-body dose was also evaluated. The MCNP simulations suggested that a lethal dose of 50 Gy to the tumors can be achieved without reaching the tolerance dose of 25 Gy to normal tissue. The whole-body phantom calculations also showed that the BNCT could be applied for brain tumors without significant damage to whole-body organs.

Matsumoto, T.

2007-09-01

431

Sonoporation as an enhancing method for boron neutron capture therapy for squamous cell carcinomas  

PubMed Central

Background Boron neutron capture therapy (BNCT) is a selective radiotherapy that is dependent on the accumulation of 10B compound in tumors. Low-intensity ultrasound produces a transient pore on cell membranes, sonoporation, which enables extracellular materials to enter cells. The effect of sonoporation on BNCT was examined in oral squamous cell carcinoma (SCC) xenografts in nude mice. Materials and methods Tumor-bearing mice were administrated boronophenylalanine (BPA) or boronocaptate sodium (BSH) intraperitoneally. Two hours later, tumors were subjected to sonoporation using microbubbles followed by neutron irradiation. Results The 10B concentration was higher in tumors treated with sonoporation than in untreated tumors, although the difference was not significant in BPA. When tumors in mice that received BPA intraperitoneally were treated with sonoporation followed by exposure to thermal neutrons, tumor volume was markedly reduced and the survival rate was prolonged. Such enhancements by sonoporation were not observed in mice treated with BSH-mediated BNCT. Conclusions These results indicate that sonoporation enhances the efficiency of BPA-mediated BNCT for oral SCC. Sonoporation may modulate the microlocalization of BPA and BSH in tumors and increase their intracellular levels.

2013-01-01

432

Boron neutron capture therapy (BNCT) for liver metastasis: therapeutic efficacy in an experimental model  

SciTech Connect

Boron neutron capture therapy (BNCT) was proposed for untreatable colorectal liver metastases. The present study evaluates tumor control and potential radiotoxicity of BNCT in an experimental model of liver metastasis. BDIX rats were inoculated with syngeneic colon cancer cells DHD/K12/TRb. Tumor-bearing animals were divided into three groups: BPABNCT, boronophenylalanine (BPA) ? neutron irradiation; Beam only, neutron irradiation; Sham, matched manipulation. The total absorbed dose administered with BPABNCT was 13 3 Gy in tumor and 9 2 Gy in healthy liver. Three weeks posttreatment, the tumor surface area post-treatment/pre-treatment ratio was 0.46 0.20 for BPABNCT, 2.7 1.8 for Beam only and 4.5 3.1 for Sham. The pre-treatment tumor nodule mass of 48 19 mgfell significantly to 19 16 mg for BPABNCT, but rose significantly to 140 106 mg for Beam only and to 346 302 mg for Sham. For both end points, the differences between the BPABNCT group and each of the other groups were statistically significant (ANOVA). No clinical, macroscopic or histological normal liver radiotoxicity was observed. It is concluded that BPA BNCT induced a significant remission of experimental colorectal tumor nodules in liver with no contributory liver toxicity.

David W. Nigg

2012-08-01

433

Calculation of Cross Section of Radiative Halo-Neutron Capture by 12C at Stellar Energy with the Asymptotic Normalization Coefficient Method  

NASA Astrophysics Data System (ADS)

The cross section of the direct neutron capture reaction 12C(n,?)13C(1/2+) is calculated with the asymptotic normalization coefficient method. The result is in good agreement with a recent experiment at low energy. An enormous enhancement of cross section is found for this direct neutron capture in which a p-wave neutron is captured into an 2s1/2 orbit with neutron halo. The possible effect of the neutron halo structure presented in this reaction on the s-process in astrophysics is discussed in general.

Wu, Kai-Su; Chen, Yong-Shou; Liu, Zu-Hua; Lin, Cheng-Jian; Zhang, Huan-Qiao

2003-01-01

434

Parity violation in neutron-proton captureThe NPDGamma experiment  

NASA Astrophysics Data System (ADS)

The NPDGamma collaboration has recently completed the first phase of a measurement to determine the size of the weak nucleon-nucleon interaction from cold neutron capture on a liquid hydrogen target. In the framework of the nearly 30 year old DDH model [B. Desplanques, J.F. Donoghue, B.R. Holstein, Annals of Physics 124 (1980) 449], the measured process is explained in terms of the weak pion-nucleon coupling, while the framework of modern effective field theory parameterizes the measured process in terms of the S13-P13, long range transition (essentially the Danilov parameter ?t) [S.L. Zhu et al., Nuclear Physics A 748 (2005) 435; C.-P. Liu, Phys. Rev. C 75 (2007) 065501]. The couplings in terms of either model are directly proportional to the parity violating up-down asymmetry in the angular distribution of gamma rays with respect to the neutron spin direction in the reaction n?+p?d+?. The asymmetry has a predicted size of 510-8 and the aim of the NPDGamma collaboration is to measure it to 20%. The first phase of the measurement was completed at the Los Alamos National Laboratory Neutron Science Center Spallation Source with a preliminary result of (-1.12.1 stat.0.2 sys.)10-7. Here, we report on the measurements and the results obtained so far. The experiment is currently being installed at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, for the remainder of its run time.

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

2009-12-01

435

Radiobiology of boron neutron capture therapy: Problems with the concept of relative biological effectiveness  

SciTech Connect

The radiation dose delivered to cells in vitro or vivo during boron neutron capture therapy (BNCT) is a mixture of photons, fast neutrons and heavy charged particles from the interaction of neutrons with nitrogen and born. The concept of relative biological effectiveness (RBE) had been developed to allow comparison of the effects of these radiations with the effects of standard photon treatments such as 250 kVp x-rays or {sup 60}Co gamma rays. The RBE value for all of these high linear energy transfer radiations can vary considerably depending upon the experimental conditions and endpoint utilized. The short range of the particles from the {sup 10}B(n,{alpha}) {sup 7}Li reaction make the precise subcellular location of the {sup 10}B atom of critical importance. The microscopic distribution of the {sup 10}B has a decided effect on the dosimetry. Monte Carlo simulations have shown that, at the cellular level, there is a profound difference in the probability of cell kill depending on the location of the {sup 10}B relative to the nucleus. Different boron-delivery agents will almost certainly have different distribution patterns at the subcellular level. The effect of BNCT with the amino acid p-boronophenylalanine (BPA) was compared with the effect of 250 kVp x-rays on a pigmented B16 melanoma subclone, both in vitro and in vivo. Generally accepted RBE values were applied to the relevant components of the Brookhaven Medical Research Reactor (BMRR) thermal neutron beam, however, there were still discrepancies when the resulting dose response curves were compared with the response to 250 kVp x-rays.

Coderre, J.A.; Makar, M.S.

1990-01-01

436

Measurement of parity-violating ?-ray asymmetry in the capture of polarized cold neutrons on protons  

SciTech Connect

The NPDGamma collaboration reports results from the first phase of a measurement of the parity violating up-down asymmetry A? with respect to the neutron spin direction of ? rays emitted in the reaction n?+p?d+? using the capture of polarized cold neutrons on the protons in a liquid parahydrogen target. One expects parity-odd effects in the hadronic weak interaction between nucleons to be induced by the weak interaction between quarks. A? in n?+p?d+? is dominated by a ?I=1, 3S1-3P1 parity-odd transition amplitude in the n-p system. The first phase of the measurement was completed at the Los Alamos Neutron Science Center spallation source (LANSCE), with the result A?=[-1.22.1?(stat.)0.2?(sys.)]10-7. We also report the first measurement of an upper limit for the parity-allowed left-right asymmetry in this reaction, with the result A?,LR=[-1.81.9?(stat.)0.2?(sys.)]10-7. In this paper we give a detailed report on the theoretical background, experimental setup, measurements, extraction of parity-odd and parity-allowed asymmetries, analysis of potential systematic effects, and LANSCE results. The asymmetry has an estimated size of 510-8 and the aim of the NPDGamma collaboration is to measure it to 110-8. The second phase of the measurement will be performed at the Spallation Neutron Source at Oak Ridge National Laboratory.

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

2011-01-01

437