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1

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

NASA Astrophysics Data System (ADS)

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

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

1981-07-01

2

Neutron Capture Reactions for Stockpile Stewardship and Basic Science  

Microsoft Academic Search

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

W Parker; U Agvaanluvsan; J Becker; P Wilk; C Wu; T Bredeweg; A Couture; R Haight; M Jandel; J ODonnell; R Reifarth; R Rundberg; J Ullmann; D Vieira; J Wouters; S Sheets; G Mitchell; F Becvar; M Krticka

2007-01-01

3

Neutron capture reactions at DANCE  

SciTech Connect

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

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

2008-05-12

4

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

5

[Epithermal neutron capture therapy  

SciTech Connect

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

Not Available

1993-01-01

6

Accelerators and Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

Within the frame of Accelerator Based Boron Neutron Capture Therapy (AB-BNCT), the 7Li (p,n) 7Be reaction, relatively near its energy threshold is one of the most promising, due to its high yield and low neutron energy. In this work a thick LiF target irradiated with a proton beam was studied as a neutron source. The 1.88-2.0 MeV proton beam was produced by the tandem accelerator TANDAR at CNEA's facilities in Buenos Aires. A water-filled phantom, containing a boron sample was irradiated with the resulting neutron flux. The 10B(n,??)7Li boron neutron capture reaction produces a 0.478 MeV gamma ray in 94% of the cases. The neutron yield was measured through the detection of this gamma ray using a hyperpure germanium detector with an anti-Compton shield. In addition, the thermal neutron flux was evaluated at different depths inside the phantom using bare and Cd-covered gold foils. A maximum neutron thermal flux of 1.4×108 cm-2s-1mA-1 was obtained at 4.2 cm from the phantom surface. In order to optimize the design of the neutron production target and the beam shaping assembly extensive Monte Carlo Neutron and Photon (MCNP) simulations have been performed. Neutron fields from a thick LiF and a Li metal target (with both a D2O-graphite and a Al/AlF3-graphite moderator/reflector assembly) were evaluated along the centerline of a head and a whole body phantom. Simulations were carried out for 1.89, 2.0 and 2.3 MeV proton beams. The results show that it is more advantageous to irradiate the target with 2.3 MeV near-resonance protons, instead of very near threshold, because of the higher neutron yield at this energy. On the other hand, the Al/AlF3-graphite exhibits a more efficient performance than D2O in terms of tumor to maximum healthy tissue dose ratio. Treatment times of less than 15 min and tumor control probabilities larger than 98% are obtained for a 50 mA, 2.3 MeV proton beam. The alternative neutron-producing reaction 13C(d,n) is also briefly reviewed. A proposal is made to construct an electrostatic, 2.5 MeV, 50 mA proton accelerator suitable for hospital use. A combination of a Tandem and an Electrostatic Quadrupole is considered to be the best option.

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

2002-08-01

7

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

8

Symmetries in Scattering of Slow Neutrons  

Microsoft Academic Search

Reciprocity, detailed balance, and other symmetry laws for slow-neutron scattering are discussed for the case of anisotropic media. While Friedel's law, stating that Sigma(v-->v')=Sigma(-v-->- v'), may fail for polar absorbing media, reciprocity as a consequence of time-reversal invariance, and of thermal equilibrium of the medium, remains valid. The optical theorem helps to derive a reciprocity relation for the total cross

I. Ku Scer; G. C. Summerfield

1969-01-01

9

Improved neutron sources for neutron capture enhanced fast neutron therapy  

SciTech Connect

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

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

2000-07-01

10

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

11

Determination of thermal neutron capture gamma yields.  

E-print Network

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

Harper, Thomas Lawrence

1969-01-01

12

Determination of thermal neutron capture gamma yields  

E-print Network

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

Harper, Thomas Lawrence

1969-01-01

13

Computer simulation of neutron capture therapy.  

E-print Network

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

Olson, Arne Peter

1967-01-01

14

Computer simulation of neutron capture therapy  

E-print Network

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

Olson, Arne Peter

1967-01-01

15

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

16

Solar Abundance of Elements from Neutron-Capture Cross Sections  

E-print Network

Excess lightweight products of slow neutron capture in the photosphere, over the mass range of 25 to 207 amu, confirm the solar mass separation recorded by excess lightweight isotopes in the solar wind, over the mass range of 3 to 136 amu [Solar Abundance of the Elements, Meteoritics, volume 18, 1983, pages 209 to 222]. Both measurements show that major elements inside the Sun are Fe, O, Ni, Si and S, like those in rocky planets.

O. Manuel; W. A. Myers; Y. Singh; M. Pleess

2004-12-19

17

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

18

Particle physics and symmetry tests with slow neutrons  

Microsoft Academic Search

In a large variety of experiments slow neutrons are used for investigations in particle physics and for tests of fundamental symmetries. Very precise measurements on the electromagnetic interactions of the neutron such as magnetic moment, rest charge or electric polarizability give insight in the internal structure of the neutron. For the free neutron beta decay the experimental data from the

K. Schreckenbach

1998-01-01

19

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

20

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

21

Biological dosimetry of neutron beams for neutron capture therapies  

E-print Network

Boron neutron capture therapies using the 10B(n,a)7Li reaction have been proposed as treatments for glioblastoma multiforme, metastatic melanoma, rheumatoid arthritis, and other debilitating conditions. This thesis presents ...

White, Susan Marie, 1973-

2001-01-01

22

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

23

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

24

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

25

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

26

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

27

Research in boron neutron capture synovectomy  

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

28

Microdosimetry for boron neutron capture therapy.  

PubMed

Preclinical studies for boron neutron capture therapy (BNCT) using epithermal neutrons are ongoing at several laboratories. The absorbed dose in tumor cells is a function of the thermal neutron flux at depth, the microscopic boron concentration, and the size of the cell. Dosimetry is therefore complicated by the admixture of thermal, epithermal, and fast neutrons, plus gamma rays, and the array of secondary high-linear-energy-transfer particles produced within the patient from neutron interactions. Microdosimetry can be a viable technique for determining absorbed dose and radiation quality. A 2.5-cm-diameter tissue-equivalent gas proportional counter has been built with 50 parts per million (ppm) 10B incorporated into the walls and counting gas to simulate the boron uptake anticipated in tumors. Measurements of lineal energy (y) spectra for BNCT in simulated volumes of 1-10 microns diameter show a dose enhancement factor of 4.3 for 30 ppm boron, and a "y" of 250 keV/microns for the boron capture process. Chamber design plus details of experimental and calculated linear energy spectra will be presented. PMID:1594762

Wuu, C S; Amols, H I; Kliauga, P; Reinstein, L E; Saraf, S

1992-06-01

29

Recent advances in neutron capture therapy (NCT)  

SciTech Connect

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

Fairchild, R.G.

1985-01-01

30

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

31

Neutron Captures in the r-Process  

E-print Network

The r-process involves neutron-rich nuclei far off stability for which no experimental cross sections are known. Therefore, one has to rely on theory. The difficulties in the predictions are briefly addressed. To investigate the impact of altered rates, a comparison of r-process production in hot bubble models with largely varied rates is shown. Due to the (n,gamma)-(gamma,n) equilibrium established at the onset of the r-process, only late-time neutron captures are important which mainly modify the abundances around the third r-process peak.

T. Rauscher

2004-04-12

32

Some lithium iodide phosphors for slow neutron detection  

Microsoft Academic Search

An account is given of the growing of single crystals of lithium iodide for use as scintillation detectors of slow and resonance energy neutrons. Tin, europium and samarium activators have been tested and their relative merits are presented. Where possible the phosphor properties are compared with a standard sodium iodide crystal. The practical application of lithium iodide crystals to neutron

K. P. Nicholson; G. F. Snelling

1955-01-01

33

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

34

Neutron Capture Experiments on Unstable Nuclei  

SciTech Connect

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

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

2005-01-15

35

Non-Statistical Effects in Neutron Capture  

SciTech Connect

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

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

2009-01-28

36

Non-Statistical Effects in Neutron Capture  

SciTech Connect

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

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

2009-01-01

37

Slow neutron detection without 3He: far ultraviolet noble-gas-excimer radiation  

E-print Network

Slow neutron detection without 3He: far ultraviolet noble-gas-excimer radiation induced by neutron (NIST) 3 Nuclear Engineering Program, UMD 4 Joint Quantum Institute, NIST and UMD Slow neutron detection. 3 He, 6 Li or 10 B initiator Slow neutron detection without 3He Eighth Ultracold Neutron Workshop

Titov, Anatoly

38

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

39

Are gadolinium contrast agents suitable for gadolinium neutron capture therapy?  

E-print Network

Are gadolinium contrast agents suitable for gadolinium neutron capture therapy? Gelsomina De Stasio Sacro Cuore, Largo A. Gemelli 8, I-00168 Roma, Italy Objective: Gadolinium neutron capture therapy (Gd compound; (2) tumor irradiation with thermal neutrons. The GdNC reaction can induce cell death provided

Gilbert, Pupa Gelsomina De Stasio

40

Neutron Capture Cross Section of 239Pu  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

41

Boron neutron capture therapy for glioblastoma.  

PubMed

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

Yamamoto, Tetsuya; Nakai, Kei; Matsumura, Akira

2008-04-18

42

Liposomal boron delivery for neutron capture therapy.  

PubMed

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

Nakamura, Hiroyuki

2009-01-01

43

Neutron producing target for accelerator based neutron capture therapy  

NASA Astrophysics Data System (ADS)

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

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

2006-05-01

44

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

E-print Network

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

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

2012-07-25

45

Neutronic effects on tungsten-186 double neutron capture  

NASA Astrophysics Data System (ADS)

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

Garland, Marc Alan

46

TRANSMISSION OF SLOW NEUTRONS THROUGH POLYCRYSTALLINE BERYLLIUM OXIDE  

Microsoft Academic Search

The variation of total scattering cross section with energy of beryllium ; oxide has been measured using a slow chopper neutron velocity spectrometer and ; the results are compared with that of the only previous reported measurements of ; Fermi et al. in 1947. (auth);

N. Sarma; K. Satyanarayana; C. S. Somanathan; K. Usha

1959-01-01

47

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

48

The Detector for Advanced Neutron Capture Experiments at LANSCE  

SciTech Connect

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

Ullmann, J.L.; Reifarth, R.; Haight, R.C.; Hunt, L.; O'Donnell, J.M.; Rundberg, R.S.; Bredeweg, T.A.; Wilhelmy, J.B.; Fowler, M.M.; Vieira, D.J.; Wouters, J.M.; Strottman, D.D. [Los Alamos National Laboratory, Los Alamos NM 87544 (United States); Kaeppeler, F.; Heil, M. [Forschungszentrum Karlsruhe, Karlsruhe, (Germany); Chamberlin, E.P. [Chamberlin Associates, Los Alamos, NM 87544 (United States)

2003-08-26

49

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

50

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

51

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

52

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

SciTech Connect

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

Farr, L.E.

1991-12-16

53

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.

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

54

Neutron Capture Cross Sections of 236U and 234U  

SciTech Connect

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

Rundberg, R. S.; Bredeweg, T. A.; Bond, E. M.; Haight, R. C.; Hunt, L. F.; O'Donnell, J. M.; Schwantes, J. M.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory (United States); Kronenberg, A. [Oak Ridge National Laboratory (United States)

2006-03-13

55

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

E-print Network

Neutron Slowing Down in a Detector with Absorption Sara A. Pozzi* Oak Ridge National Laboratory, P of scattering collisions undergone by fast neutrons as they slow down until they are absorbed was presented realistic case of neutron slowing down in a homogeneous mixture. The formulas are derived and evaluated

Pázsit, Imre

56

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

57

Neutron Capture Experiments on Unstable Nuclei  

SciTech Connect

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

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

2003-12-16

58

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

59

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

60

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

61

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

62

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

63

Heterogeneous Neutron Capture Record of the Norton County Enstatite Achondrite  

NASA Astrophysics Data System (ADS)

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

Hidaka, H.; Yoneda, S.

2012-09-01

64

Hypoxia-selective compounds for boron neutron capture therapy  

E-print Network

Boron neutron capture therapy (BNCT) is a biochemically targeted form of radiotherapy for cancer. In BNCT, a compound labeled with the stable isotope boron-10 is systemically administered, and tumor cells selectively uptake ...

Shah, Jungal (Jugal Kaushik)

2008-01-01

65

Radiobiology of normal rat lung in Boron Neutron Capture Therapy  

E-print Network

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

Kiger, Jingli Liu

2006-01-01

66

Computational aspects of treatment planning for neutron capture therapy  

E-print Network

Boron Neutron Capture Therapy (BNCT) is a biochemically targeted form of binary radiation therapy that has the potential to deliver radiation to cancers with cellular dose selectivity. Accurate and efficient treatment ...

Albritton, James Raymond, 1977-

2010-01-01

67

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 calorimeter—Detector 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

68

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

69

Neutron-Capture gamma Rays from Various Elements  

Microsoft Academic Search

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

T. H. Braid

1956-01-01

70

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

SciTech Connect

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

Farr, L.E.

1991-12-16

71

Rapid neutron capture process in supernovae and chemical element formation  

Microsoft Academic Search

The rapid neutron capture process (r-process) is one of the major nucleosynthesis processes responsible for the synthesis\\u000a of heavy nuclei beyond iron. Isotopes beyond Fe are most exclusively formed in neutron capture processes and more heavier\\u000a ones are produced by the r-process. Approximately half of the heavy elements with mass number A > 70 and all of the actinides in

Rulee Baruah; Kalpana Duorah; H. L. Duorah

2009-01-01

72

NSTAR—A capture gated plastic neutron detector  

NASA Astrophysics Data System (ADS)

NSTAR (Neutron Sandwich Transmuter/Activation- ? Radiator) prototypes were developed and their performances were evaluated using radioactive sources and a pulsed neutron beam. The NSTAR operating principle is similar to that of Gd-loaded liquid scintillation detectors, where the scintillator has dual functions as neutron moderator and sensor of delayed capture ?-rays, but spatially separates scintillator from neutron converter components. The time dependent NSTAR response to neutrons consists of a prompt, energy related light flash followed by a delayed signal characteristic in both light output and delay time. This feature allows one to discriminate on average between neutrons and ?-rays and provides the basis for multiplicity determination. The detectors are scalable, economic to construct of environmentally benign components, and can be ruggedized. Prototype detector modules consist of 12×20×(50 or 100) cm 3 stacks of plastic scintillator slabs (Saint Gobain BC-408) alternating with thin Gd converter films viewed by fast photomultipliers (Philips XP2041). The effective Gd/scintillator ratio is 0.5 wt%. Results of tests of NSTAR with 252Cf and neutrons from the D(d,n) 3He reactions are in good agreement with theoretical estimates based on neutron transport simulations. Characteristics of the detector module include an average neutron capture time of =21.7±0.2 ?s and a detection efficiency of ?=26±3% for DD neutrons. The NSTAR has been applied to determine the multiplicity distribution of neutrons produced in D(d,n) 3He reactions by a neutron generator.

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

2011-02-01

73

Gamma-ray spectra from neutron capture on Sr  

Microsoft Academic Search

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

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

1981-01-01

74

Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments  

E-print Network

Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments Michael J Department Troy, New York 12180-3590 Abstract. The focus of this work is to determine resonance parameters and 178 Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion

Danon, Yaron

75

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

SciTech Connect

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

Couture, A.; Bond, E.; Bredeweg, T. A.; Fowler, M.; Haight, R. C.; Jandel, M.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States); Agvaanluvsan, U.; Becker, J. A. [Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94551 (United States); Baker, J. D. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States); Bayarbadrahk, B.; Chyzh, A.; Dashdorj, D. [North Carolina State University, Department of Physics, Raleigh, NC 27695 (United States); Reifarth, R. [Gesellschaft fuer Schwerionenforschung (GSI), Plankstrasse 1, 64291 Darmstadt (Germany)

2009-03-10

76

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

77

Direct measurements of neutron capture on radioactive isotopes  

E-print Network

We simulated the response of a 4p calorimetric g-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 4p arrays using the time of flight technique.

A. Couture; R. Reifarth

2009-09-30

78

Slowing-down and Coulomb capture of negative muons in the hydrogen-helium isotope mixtures  

NASA Astrophysics Data System (ADS)

This paper reports the results of the theoretical study of ionization and Coulomb capture in collisions of slow negative muons with atoms of H, He and molecules of hydrogen isotopes. The cross sections and the kinetic characteristics of these processes in the mixture of molecules of hydrogen isotopes and helium atoms are calculated.

Balashov, V. V.; Dolinov, V. K.; Korenman, G. Ya.; Leonova, S. V.; Moskalenko, I. V.; Popov, V. P.

79

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

80

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

Microsoft Academic Search

A modified neutron production target assembly has been developed to provide improved performance of the proton-cyclotron-based neutron radiotherapy facility at the University of Washington for applications involving neutron capture enhanced fast-neutron therapy. The new target produces a neutron beam that yields essentially the same fast-neutron physical depth-dose distribution as is produced by the current UW clinical system, but that also

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

2000-01-01

81

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

E-print Network

The scattering of slow neutron beams provides unique, non-destructive, quantitative information on the structure and dynamics of materials of interest in physics, chemistry, materials science, biology, geology, and other fields. Liquid hydrogen is a widely-used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. In particular the rapid drop of the slow neutron scattering cross section of liquid parahydrogen below 15 meV, which renders the moderator volume transparent to the neutron energies of most interest for scattering studies, is therefore especially interesting and important. We have placed an upper bound on the total cross section and the scattering cross section for slow neutrons with energies between 0.43 meV and 16.1 meV on liquid hydrogen at 15.6 K using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. At 1 meV this new upper bound is a factor of 3 below the data from previous work which has been used in the design of liquid hydrogen moderators at slow neutron sources. We describe our measurements, compare them with previous work, and discuss the implications for designing more intense slow neutron sources.

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

2014-10-08

82

Neutron capture therapy beam design at Harwell.  

PubMed

At Harwell, we have progressed from designing, building, and using small-diameter beams of epithermal neutrons for radiobiology studies to designing a radiotherapy facility for the 25-MW research reactor DIDO. The program is well into the survey phase, where the main emphasis is on tailoring the neutron spectrum. The incorporation of titanium and vanadium in an aluminium spectrum shaper in the D2O reflector has been shown to yield a significant reduction in the mean energy of neutrons incident on the patient by suppression of streaming through the cross-section window in aluminium at 25 keV. PMID:2176459

Constantine, G

1990-01-01

83

Neutron capture reactions on Lu isotopes at DANCE  

E-print Network

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

Roig, O

2010-01-01

84

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

85

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

86

A SIMPLE CALIBRATION AND CHECKING FACILITY FOR FAST AND SLOW NEUTRON DETECTORS  

Microsoft Academic Search

A simple facility is described for checking the sensi-tivity of dose ; rate instruments for fast neutron detection, and for calibration of thermal ; neutron detectors. About 7 million plutonium-beryllium neutrons per second give ; a tolerance flux density of slow neutrons from the walls of a cavity in paraffin ; or water. Construction drawings of the cavity are given,

Redmond

1959-01-01

87

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

88

Sublethal and potentially lethal damage repair on thermal neutron capture therapy  

SciTech Connect

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

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

1989-07-01

89

Progress on the Europium Neutron-Capture Study using DANCE  

SciTech Connect

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

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

2006-09-05

90

Neutron Capture and Fission Measurements on Actinides at DANCE  

NASA Astrophysics Data System (ADS)

Neutron capture and fission measurements on actinides are important in nuclear engineering and physics. DANCE (Detector for Advanced Neutron Capture Measurement build at LANL) together with PPAC (avalanche technique based fission tagging detector designed and fabricated at LLNL) were used to measure the prompt ?-ray energy and multiplicity distributions in the spontaneous fission of ^252Cf. These measured spectra together with the unfolded ones will be presented. The unfolding technique will be described. In addition the ^238Pu(n,?) cross section will be presented, which was measured using DANCE alone and also is the first such measurement in a laboratory environment.

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

2011-10-01

91

Neutron capture and transmission measurements on fission product palladium-107  

Microsoft Academic Search

Neutron capture and transmission measurements were made on a sample of fission-product palladium. The level parameters were obtained for 34 ¹°⁷Pd resonances below 700 eV. The observed average level spacing was = (10.7 +- 1.5) eV, and the s-wave neutron strength function was determined to be 10⁴ Sâ = (0.56\\/sup +0\\/.¹⁶\\/sub -0.12\\/). The capture width Gamma\\/sub ..gamma..\\/ for the

U. N. Singh; R. C. Block; Y. Nakagome

1978-01-01

92

Stellar neutron capture cross sections of the Yb isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 170Yb, 171Yb, 172Yb, 173Yb, 174Yb, and 176Yb have been measured in the energy range from 3 to 225 keV relative to the gold standard. Neutrons were produced at the Karlsruhe 3.75 MV Van de Graaff Accelerator via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam, and capture events were registered with the Karlsruhe 4? Barium Fluoride Detector. Neutron capture in the even ytterbium isotopes is characterized by a strong population of isomeric states, leading to unrecognized systematic uncertainties in previous measurements. For the first time, partial cross sections to ground and isomeric states could be experimentally identified in neutron time-of-flight measurements for 172Yb, 173Yb, 174Yb, and 176Yb. The present overall uncertainties of (1-1.5) % correspond to an improvement by factors of 4-10 compared to existing data. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=8 keV and 100 keV. In four cases, the results differ by more than 15% from recent evaluations. The s-process analyses based on the present data provide further evidence in favor of stellar models for thermally pulsing low-mass asymptotic giant branch stars.

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

2000-06-01

93

New measurement of neutron capture resonances in Bi209  

Microsoft Academic Search

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

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

2006-01-01

94

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

PubMed

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

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

2002-09-01

95

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

SciTech Connect

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

Jandel, M.; Bredeweg, T. A.; Fowler, M. M.; Bond, E. M.; Couture, A.; Haight, R. C.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Stoyer, M. A.; Wu, C. Y.; Becker, J. A.; Haslett, R. J.; Henderson, R. A. [Lawrence Livermore National Laboratory, Livermore, CA, 94550 (United States)

2009-01-28

96

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

SciTech Connect

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

Jandel, Marian [Los Alamos National Laboratory

2008-01-01

97

Neutron capture cross section of {sup 241}Am  

SciTech Connect

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

Jandel, M.; Bredeweg, T. A.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O'Donnell, J. M.; Haight, R. C.; Kawano, T.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Agvaanluvsan, U.; Parker, W. E.; Wu, C. Y.; Becker, J. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2008-09-15

98

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

99

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

100

Thermal Neutron Capture Cross Sections of the PalladiumIsotopes  

SciTech Connect

Precise gamma-ray thermal neutron capture cross sectionshave been measured at the Budapest Reactor for all elements withZ=1-83,92 except for He and Pm. These measurements and additional datafrom the literature been compiled to generate the Evaluated Gamma-rayActivation File (EGAF), which is disseminated by LBNL and the IAEA. Thesedata are nearly complete for most isotopes with Z<20 so the totalradiative thermal neutron capture cross sections can be determineddirectly from the decay scheme. For light isotopes agreement with therecommended values is generally satisfactory although large discrepanciesexist for 11B, 12,13C, 15N, 28,30Si, 34S, 37Cl, and 40,41K. Neutroncapture decay data for heavier isotopes are typically incomplete due tothe contribution of unresolved continuum transitions so only partialradiative thermal neutron capture cross sections can be determined. Thecontribution of the continuum to theneutron capture decay scheme arisesfrom a large number of unresolved levels and transitions and can becalculated by assuming that the fluctuations in level densities andtransition probabilities are statistical. We have calculated thecontinuum contribution to neutron capture decay for the palladiumisotopes with the Monte Carlo code DICEBOX. These calculations werenormalized to the experimental cross sections deexciting low excitationlevels to determine the total radiative thermal neutron capture crosssection. The resulting palladium cross sections values were determinedwith a precision comparable to the recommended values even when only onegamma-ray cross section was measured. The calculated and experimentallevel feedings could also be compared to determine spin and parityassignments for low-lying levels.

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

2006-07-17

101

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

102

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=13.5±0.2, 14.1±0.2, and 14.8±0.2 MeV are found to be 1.30±0.08, 1.15±0.08 and 0.99±0.07 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

103

Stellar neutron capture cross sections of the Yb isotopes.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 170Yb, 171Yb, 172Yb, 173Yb, 174Yb, and 176Yb have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? barium fluoride detector. The cross sections were determined relative to the gold standard. Neutron capture in the even ytterbium isotopes is characterized by a strong population of isomeric states, resulting in severe systematic uncertainties in previous experiments. In the present work, the partial cross sections to the ground- and isomeric states in 172Yb, 174Yb, 176Yb could be experimentally separated for the first time, yielding cross section ratios with an overall uncertainty of 1 - 1.5%. Compared to previous measurements, this corresponds to an improvement by factors of 4 to 10. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 8 keV and 100 keV. The results of four isotopes differ by more than 15% from recent evaluations.

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

1998-11-01

104

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

105

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments  

E-print Network

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments M. J ­ The focus of this work is to determine the resonance parameters for stable hafnium isotopes in the 0.005- to 200-eV region, with special emphasis on the overlapping 176Hf and 178Hf resonances near 8 eV. Accurate

Danon, Yaron

106

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

107

Gamma Spectrum from Neutron Capture on Tungsten Isotopes  

SciTech Connect

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

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

2010-04-29

108

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

109

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

E-print Network

The scattering of slow neutron beams provides unique, non-destructive, quantitative information on the structure and dynamics of materials of interest in physics, chemistry, materials science, biology, geology, and other fields. Liquid hydrogen is a widely-used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. In particular the rapid drop of the slow neutron scattering cross section of liquid parahydrogen below 15 meV, which renders the moderator volume transparent to the neutron energies of most interest for scattering studies, is therefore especially interesting and important. We have placed an upper bound on the total cross section and the scattering cross section for slow neutrons with energies between 0.43 meV and 16.1 meV on liquid hydrogen at 15.6 K using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge Nati...

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

2014-01-01

110

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

111

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

Microsoft Academic Search

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

Thomas E. Blue; Jacquelyn C. Yanch

2003-01-01

112

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

Microsoft Academic Search

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

Thomas E. Blue; Jacquelyn C. Yanch

2003-01-01

113

Stellar neutron capture cross sections of the tin isotopes.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 114Sn, 115Sn, 116Sn, 117Sn, 118Sn, and 120Sn were measured in the enrgy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p, n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector, which was improved by replacing crystals with high ? background. This allowed to lower the threshold in sum energy and resulted in a significantly increased efficiency for capture events. The experiment was difficult due to the small (n, ?) cross sections of the proton magic tin isotopes, and due to the comparably low enrichment of the rare isotopes 114Sn and 115Sn. This caused significant corrections for capture of scattered neutrons and for isotopic impurities, but the high efficiency and the spectroscopic quality of the BaF2 detector allowed to determine these corrections reliably. Typical overall uncertainties of 1 - 2% could be achieved for the cross section ratios, five times smaller compared to existing data. Based on these results, Maxwellian averaged (n, ?) cross sections were calculated for thermal energies between kT = 10 keV and 100 keV.

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

1995-08-01

114

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

115

Review of Livermore-Led Neutron Capture Studies Using DANCE  

SciTech Connect

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

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

2007-05-11

116

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

117

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

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

118

Neutron Capture Cross Sections for the Re\\/Os Clock  

Microsoft Academic Search

The radioactive decay of 187Re --> 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 sigmaN systematics using the neighboring s-only isotope 186Os, provided the neutron-capture cross sections

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

2005-01-01

119

Dependence of direct neutron capture on nuclear-structure models  

Microsoft Academic Search

The prediction of cross sections for nuclei far off stability is crucial in the field of nuclear astrophysics. We calculate direct neutron capture on the even-even isotopes 124-145Sn and 208-238Pb with energy levels, masses, and nuclear density distributions taken from different nuclear-structure models. The utilized structure models are a Hartree-Fock-Bogoliubov model, a relativistic mean field theory, and a macroscopic-microscopic model

T. Rauscher; R. Bieber; H. Oberhummer; K.-L. Kratz; J. Dobaczewski; P. Möller; M. M. Sharma

1998-01-01

120

Stellar neutron capture cross sections of the Gd isotopes  

NASA Astrophysics Data System (ADS)

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

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

1995-11-01

121

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

122

MCNP speed advances for boron neutron capture therapy  

Microsoft Academic Search

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

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

1998-01-01

123

Stellar neutron capture cross sections of the Nd isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 142Nd, 143Nd, 144Nd, 145Nd, 146Nd, and 148Nd have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector. The cross sections were determined relative to the gold standard. The experiment was difficult due to the small cross sections of the even isotopes at or near the magic neutron number N=82, and also since the isotopic enrichment of some samples was comparably low. The necessary corrections for capture of scattered neutrons and for isotopic impurities could be determined reliably thanks to the high efficiency and the spectroscopic quality of the BaF2 detector, resulting in a consistent set of (n,?) cross sections for the six stable neodymium isotopes involved in the s process with typical uncertainties of 1.5-2 %. From these data, Maxwellian averaged cross sections were calculated between kT=10 and 100 keV. The astrophysical implications of these results were investigated in an s-process analysis, which deals with the role of the s-only isotope 142Nd for the Ns systematics near the magic neutron number N=82, the decomposition of the Nd abundances into the respective r-, s-, and p-process components, and the interpretation of isotopic anomalies in meteoritic material.

Wisshak, K.; Voss, F.; Käppeler, F.; Kazakov, L.; Reffo, G.

1998-01-01

124

Stellar neutron capture cross sections of the Lu isotopes  

NASA Astrophysics Data System (ADS)

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

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

2006-01-01

125

Stellar neutron capture cross sections of the tin isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 114Sn, 115Sn, 116Sn, 117Sn, 118Sn, and 120Sn were measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction using a pulsed proton beam. Capture events were registered with the Karlsruhe 4? barium fluoride detector. The experiment was complicated by the small (n,?) cross sections of the proton magic tin isotopes and by the comparably low enrichment of the rare isotopes 114Sn and 115Sn. Despite significant corrections for capture of scattered neutrons and for isotopic impurities, the high efficiency and the spectroscopic quality of the BaF2 detector allowed the determination of the cross-section ratios with overall uncertainties of 1-2 %, five times smaller compared to existing data. Based on these results, Maxwellian averaged (n,?) cross sections were calculated for thermal energies between kT=10 and 100 keV. These data are used for a discussion of the solar tin abundance and for an improved determination of the isotopic s- and r-process components.

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

1996-09-01

126

Neutron capture cross sections for stellar Cd production  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 110Cd, 111Cd, 112Cd, 113Cd, 114Cd, and 116Cd have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. The Karlsruhe 4? barium fluoride detector was used for registration of capture events. The cross sections were determined relative to the gold standard using highly enriched metallic Cd samples. The respective ratios could be obtained with overall uncertainties between 0.8% and 1.6%, about an order of magnitude more accurate than previous data. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=8 keV and 100 keV. Discrepancies of 30% to 40% were found with respect to previous data. The new cross sections provide a reliable definition of the s-abundance pattern of the Cd isotopes, thus improving the corresponding r-process residuals, and, most importantly, the impact of s-only 110Cd as a normalization point for the overall distribution of the s abundances.

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

2002-08-01

127

Stellar neutron capture cross sections of the tin isotopes  

SciTech Connect

The neutron capture cross sections of {sup 114}Sn, {sup 115}Sn, {sup 116}Sn, {sup 117}Sn, {sup 118}Sn, and {sup 120}Sn 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 {sup 7}Li({ital p},{ital n}){sup 7}Be reaction using a pulsed proton beam. Capture events were registered with the Karlsruhe 4{pi} barium fluoride detector. The experiment was complicated by the small ({ital n},{gamma}) cross sections of the proton magic tin isotopes and by the comparably low enrichment of the rare isotopes {sup 114}Sn and {sup 115}Sn. Despite significant corrections for capture of scattered neutrons and for isotopic impurities, the high efficiency and the spectroscopic quality of the BaF{sub 2} detector allowed the determination of the cross-section ratios with overall uncertainties of 1{endash}2{percent}, five times smaller compared to existing data. Based on these results, Maxwellian averaged ({ital n},{gamma}) cross sections were calculated for thermal energies between {ital kT}=10 and 100 keV. These data are used for a discussion of the solar tin abundance and for an improved determination of the isotopic {ital s}- and {ital r}-process components. {copyright} {ital 1996 The American Physical Society.}

Wisshak, K.; Voss, F.; Theis, C.; Kaeppeler, F. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany)] [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, Postfach 3640, D-76021 Karlsruhe (Germany); Guber, K. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)] [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Kazakov, L.; Kornilov, N. [Institute for Physics and Power Engineering, Obninsk, Kaluga Region (Russia)] [Institute for Physics and Power Engineering, Obninsk, Kaluga Region (Russia); Reffo, G. [Comitato Nazionale per la Ricerca e per lo Sviluppo dell`Energia Nucleare e delle Energia Alternative, Centro Dati Nucleari, Via Martiri di Monte Sole 4, I-40138 Bologna (Italy)] [Comitato Nazionale per la Ricerca e per lo Sviluppo dell`Energia Nucleare e delle Energia Alternative, Centro Dati Nucleari, Via Martiri di Monte Sole 4, I-40138 Bologna (Italy)

1996-09-01

128

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

129

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

130

Thermal neutron capture cross sections of the potassium isotopes  

NASA Astrophysics Data System (ADS)

Precise thermal neutron capture ?-ray cross sections ?? for 39,40,41K were measured on a natural potassium target with the guided neutron beam at the Budapest Reactor. The cross sections were internally standardized using a stoichiometric KCl target with well-known 35Cl(n,?) ?-ray cross sections [Révay and Molnár, Radiochimica ActaRAACAP0033-823010.1524/ract.91.6.361.20027 91, 361 (2003); Molnár, Révay, and Belgya, Nucl. Instrum. Meth. Phys. Res. BNIMBEU0168-583X10.1016/S0168-583X(03)01529-5 213, 32 (2004)]. These data were combined with ?-ray intensities from von Egidy [von Egidy, Daniel, Hungerford, Schmidt, Lieb, Krusche, Kerr, Barreau, Borner, Brissot , J. Phys. G. Nucl. Phys.JPHGBM0305-461610.1088/0305-4616/10/2/013 10, 221 (1984)] and Krusche [Krusche, Lieb, Ziegler, Daniel, von Egidy, Rascher, Barreau, Borner, and Warner, Nucl. Phys. ANUPABL0375-947410.1016/0375-9474(84)90506-2 417, 231 (1984); Krusche, Winter, Lieb, Hungerford, Schmidt, von Egidy, Scheerer, Kerr, and Borner, Nucl. Phys. ANUPABL0375-947410.1016/0375-9474(85)90429-4 439, 219 (1985)] to generate nearly complete capture ?-ray level schemes. Total radiative neutron cross sections were deduced from the total ?-ray cross section feeding the ground state, ?0=???(GS) after correction for unobserved statistical ?-ray feeding from levels near the neutron capture energy. The corrections were performed with Monte Carlo simulations of the potassium thermal neutron capture decay schemes using the computer code dicebox where the simulated populations of low-lying levels are normalized to the measured cross section depopulating those levels. Comparisons of the simulated and experimental level feeding intensities have led to proposed new spins and parities for selected levels in the potassium isotopes where direct reactions are not a significant contribution. We determined the total radiative neutron cross sections ?0(39K)=2.28±0.04 b, ?0(40K)=90±7 b, and ?0(41K)=1.62±0.03 b from the prompt ?-ray data and the ?-ray transition probability P?(1524.66)=0.164(4) in the ?- decay of 42K in a low-background counting experiment.

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

2013-02-01

131

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

SciTech Connect

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

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

1989-01-01

132

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments  

SciTech Connect

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

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

2004-10-13

133

Stellar neutron capture cross sections of the Gd isotopes.  

NASA Astrophysics Data System (ADS)

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

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

1995-05-01

134

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

SciTech Connect

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

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

2007-07-18

135

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

Microsoft Academic Search

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

1958-01-01

136

Neutron slowing down via inelastic scattering in heavy moderators. I. Steady state  

Microsoft Academic Search

The inelastic scattering of neutrons by nuclei has been treated ; historically as a stepchild of elastic scattering. Few analytical studies have ; been performed which focus attention on inelastic scattering as a primary energy ; transfer mechanism. Neutrons slowing down in the presence of inelastic ; scatterers are considered. The host nuclei is assumed to be very heavy, so

M. J. Lineberry; N. Corngold

1974-01-01

137

SLOWING DOWN AND DIFFUSION LENGTHS OF NEUTRONS IN GRAPHITE-BISMUTH SYSTEMS  

Microsoft Academic Search

Exponential experiments were performed to measure the slowing down ; lengths and diffusion lengths of neutrons in graphite-bismuth lattices. The ; lattices were composed of graphite and bismuth bars, each approximately 1 x 1 x ; 24 in., with a small amount of aluminum foil, which will eventually be replaced ; by uranium foils for experiments related to neutron multiplication.

J. M. Hendrie; J. P. Phelps; G. A. Price; E. V. Weinstock

1958-01-01

138

Particle physics with slow neutrons; a personal and biased outlook  

Microsoft Academic Search

This review is devoted to recent advances in the physics of cold and ultra-cold neutrons reported at this workshop, in so far as they bear on current problems in particle physics both within and beyond the Standard Model. Attention is directed primarily to developments in the experimental study of neutron decay and to searches for the breakdown of T-invariance, either

J. Byrne

2000-01-01

139

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

NASA Astrophysics Data System (ADS)

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

Gönnenwein, F.

2014-09-01

140

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

141

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

NASA Astrophysics Data System (ADS)

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

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

2005-07-01

142

Stellar neutron capture cross sections of the Ba isotopes  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 134Ba, 135Ba, 136Ba, and 137Ba 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 7Li (p,n)7 Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? barium fluoride detector. The cross section ratios were determined with an overall uncertainty of ~3%, an improvement by factors of 5 to 8 compared to existing data. Severe discrepancies were found with respect to previous results. As a new possibility in time of flight experiments, isomeric cross section ratios could be determined for 135Ba, 136Ba, and 137Ba. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT=10 keV and 100 keV. These stellar cross sections were used in an s-process analysis. For the s-only isotopes 134Ba and 136Ba the Ns ratio was determined to 0.875+/-0.025. Hence, a significant branching of the s-process path at 134Cs can be claimed for the first time, in contrast to predictions from the classical approach. This branching yields information on the s-process temperature, indicating values around T8=2. The new cross sections are also important for the interpretation of barium isotopic anomalies, which were recently discovered in SiC grains of carbonaceous chondrite meteorites. Together with the results from previous experiments on tellurium and samarium, a general improvement of the Ns systematics in the mass range A=120-150 is achieved. This yields a more reliable separation of s- and r-process contributions for comparison with stellar observations, but reveals a 20% discrepancy with respect to the solar barium abundance.

Voss, F.; Wisshak, K.; Guber, K.; Käppeler, F.; Reffo, G.

1994-11-01

143

Neutron capture cross section of Zr90: Bottleneck in the s-process reaction flow  

Microsoft Academic Search

The neutron capture cross sections of the Zr isotopes have important implications in nuclear astrophysics and for reactor design. The small cross section of the neutron magic nucleus Zr90, which accounts for more than 50% of natural zirconium represents one of the key isotopes for the stellar s-process, because it acts as a bottleneck in the neutron capture chain between

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

2008-01-01

144

Neutron capture cross section measurements for nuclear astrophysics at CERN n_TOF  

Microsoft Academic Search

A series of neutron capture cross section measurements of interest to nuclear astrophysics have been recently performed at n_TOF, the neutron spallation source operating at CERN. The low repetition frequency of the proton beam driver, the extremely high instantaneous neutron flux, and the low background conditions in the experimental area are optimal for capture cross section measurements on low-mass or

U. Abbondanno; G. Aerts; F. Alvarez-Velarde; H. Álvarez-Pol; S. Andriamonje; J. Andrzejewski; G. Badurek; P. Baumann; F. Becvár; J. Benlliure; E. Berthoumieux; F. Calviño; D. Cano-Ott; R. Capote; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; D. Cortina; A. Couture; J. Cox; S. Dababneh; M. Dahlfors; S. David; R. Dolfini; C. Domingo-Pardo; I. Duran; M. Embid-Segura; L. Ferrant; A. Ferrari; R. Ferreira-Marques; H. Frais-Kölbl; W. Furman; I. Goncalves; R. Gallino; E. Gonzalez-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; F. Gunsing; B. Haas; R. Haight; M. Heil; A. Herrera-Martinez; S. Isaev; E. Jericha; F. Käppeler; Y. Kadi; D. Karadimos; V. Ketlerov; P. Koehler; V. Konovalov; M. Krticka; C. Lamboudis; H. Leeb; A. Lindote; I. Lopes; G. Lorusso; M. Lozano; S. Lukic; J. Marganiec; S. Marrone; J. Martinez-Val; P. Mastinu; A. Mengoni; P. M. Milazzo; A. Molina-Coballes; C. Moreau; M. Mosconi; F. Neves; H. Oberhummer; S. O'Brien; J. Pancin; T. Papaevangelou; C. Paradela; A. Pavlik; P. Pavlopoulos; J. M. Perlado; L. Perrot; M. Pignatari; R. Plag; A. Plompen; A. Plukis; A. Poch; A. Policarpo; C. Pretel; J. Quesada; W. Rapp; T. Rauscher; R. Reifarth; M. Rosetti; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; J. C. Soares; C. Stephan; G. Tagliente; J. L. Tain; L. Tassan-Got; L. Tavora; R. Terlizzi; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M. C. Vincente; V. Vlachoudis; F. Voss; H. Wendler; M. Wiescher; K. Wisshak

2005-01-01

145

Real-time dosimetry for boron-neutron capture therapy  

SciTech Connect

Epithermal/thermal boron neutron-capture therapy (BNCT) is promising treatment method for malignant tumors. Because the doses and dose rates for medical therapeutic radiation are very close to the normal tissue tolerance, small errors in radiation delivery can result in harmful overdoses. A substantial need exists for a device that will monitor, in real time, the radiation dose being delivered to a patient. Pacific Northwest Laboratory (PNL) has developed a scintillating glass optical fiber that is sensitive to thermal neutrons. The small size of the fibers offers the possibility of in vivo dose monitoring at several points within the radiation field. The count rate of such detectors can approach 10 MHz because the lifetime of the cerium activator is fast. Fluxes typical of those in BNCT (i.e., 10{sup 9} n/cm{sup 2}/sec) may be measured because of this potentially high count rate and the small diameter of the fiber.

Bliss, M.; Craig, R.A.; Reeder, P.L.; Sunberg, D.S.

1994-09-01

146

Isodose Curves and Treatment Planning for Boron Neutron Capture Therapy.  

NASA Astrophysics Data System (ADS)

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

Liu, Hungyuan B.

147

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

148

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

149

Is Germanium (Ge, Z=32) A Neutron-Capture Element?  

E-print Network

Historically,Ge has been considered to be a neutron-capture element. In this case, the r-process abundance of Ge is derived by subtracting the s-process abundance from the total abundance in the Solar system. However, the Ge abundance of the metal-poor star HD 108317 is lower than that of the scaled residual r-process abundance in the Solar system, about 1.2 dex. In this paper, based on a comparison of the Ge abundances of metal-poor stars and stellar yields, we find that the Ge abundances are not the result of the primary-like yields in massive stars and come mainly from the r-process. Based on the observed abundances of metal-poor stars, we derived the Ge abundances of the weak r-process and main r-process. The contributed percentage of the neutron-capture process to Ge in the Solar system is about 59 per cent, which means that the contributed percentage of the Ge residual abundance in the Solar system is about 41 per cent. We find that the Ge residual abundance is produced as secondary-like yields in massi...

Niu, Ping; Cui, Wenyuan; Zhang, Bo

2014-01-01

150

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

151

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

152

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

153

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

154

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

155

Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

156

Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy  

SciTech Connect

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

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

2010-08-04

157

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

158

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.

159

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

160

Neutron-capture elements in the very metal-poor star HD88609: another st ar with excesses of light neutron-capture elements  

E-print Network

We obtained a high resolution, high signal-to-noise UV-blue spectrum of the extremely metal-poor red giant HD88609 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 HD122563 that was studied by 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.

Satoshi Honda; Wako Aoki; Yuhri Ishimaru; Shinya Wanajo

2007-05-27

161

Uncertainties in Hauser-Feshbach Neutron Capture Calculations for Astrophysics  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

162

Scissors mode of Gd nuclei studied from resonance neutron capture  

SciTech Connect

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

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

2012-10-20

163

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

164

PGNAA of human arthritic synovium for boron neutron capture synovectomy  

SciTech Connect

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

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

1997-12-01

165

Gadolinium as an element for neutron capture therapy  

SciTech Connect

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

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

1992-01-01

166

Gadolinium as an element for neutron capture therapy  

SciTech Connect

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

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

1992-12-31

167

Tidal capture of primordial black holes by neutron stars  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

168

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

SciTech Connect

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

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

2000-02-01

169

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

PubMed

A modified neutron production target assembly has been developed to provide improved performance of the proton-cyclotron-based neutron radiotherapy facility at the University of Washington for applications involving neutron capture enhanced fast-neutron therapy. The new target produces a neutron beam that yields essentially the same fast-neutron physical depth-dose distribution as is produced by the current UW clinical system, but that also has an increased fraction of BNCT enhancement relative to the total therapeutic dose. The modified target is composed of a 5-millimeter layer of beryllium, followed by a 2.5-millimeter layer of tungsten, with a water-cooled copper backing. Measurements of the free-field neutron spectrum of the beam produced by the new target were performed using activation foils with a direct spectral unfolding technique. Water phantom measurements were performed using a tissue-equivalent ion chamber to characterize the fast-neutron depth-dose curve and sodium activation in soda-lime glass beads to characterize the thermal-neutron flux (and thus the expected neutron capture dose enhancement) as a function of depth. The results of the various measurements were quite consistent with expectations based on the design calculations for the modified target. The spectrum of the neutron beam produced by the new target features an enhanced low-energy flux component relative to the spectrum of the beam produced by the standard UW target. However, it has essentially the same high-energy neutron flux, with a reduced flux component in the mid-range of the energy spectrum. As a result, the measured physical depth-dose curve in a large water phantom has the same shape compared to the case of the standard UW clinical beam, but approximately twice the level of BNCT enhancement per unit background neutron dose at depths of clinical interest. In-vivo clinical testing of BNCT-enhanced fast-neutron therapy for canine lung tumors using the new beam was recently initiated. PMID:10718140

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

2000-02-01

170

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

171

Development of a terbium-lithium glass for slow neutron detection  

Microsoft Academic Search

We have developed a new terbium-doped, lithium-loaded scintillating glass for slow neutron detection. This glass has the advantages of an emission spectrum with a maximum at 550 nm and of being drawn easily into optical fibers for the fabrication of scintillating optical fiber plates.

G. Zanella; R. Zannoni; R. Dall'Igna; P. Polato; M. Bettinelli

1995-01-01

172

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

173

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

174

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

PubMed

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

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

2004-11-01

175

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

176

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.; Révay, Zs.; Szentmiklósi, L.; Basunia, M. S.; Belgya, T.; Escher, J. E.; Krti?ka, M.

2014-01-01

177

Muon capture on deuteron and the neutron-neutron scattering length  

E-print Network

The muon capture reaction mu + 2H --> nu_mu + n + n is studied with nuclear potentials and charge-changing weak currents, derived within chiral effective field theory. The next-to-next-to-next-to leading order (N3LO) chiral potential with cutoff parameter Lambda=500 MeV is used, but the low-energy constant (LEC) determining the neutron-neutron S-wave scattering length (a_{nn}) is varied so as to obtain four different values, which are a_{nn}=-18.95 fm, -16.0 fm, -22.0 fm, and +18.22 fm. The first value is the present empirical one, while the last one is chosen such as to lead to a di-neutron bound system with a binding energy of 139 keV. The LEC's c_D and c_E, present in the three-nucleon potential and axial-vector current (c_D), are constrained to reproduce the A=3 binding energies and the triton Gamow-Teller matrix element. The muon capture rate on the deuteron in the doublet hyperfine initial state is found to be 399(3) s^{-1} for a_{nn}=-18.95 and -16.0 fm; and 400(3) s^{-1} for a_{nn}=-22.0 fm. However, in the case of a_{nn}=+18.22 fm, the result of 275(3) s^{-1} (135(3) s^{-1}) is obtained, when the di-neutron system in the final state is unbound (bound). The muon capture mu + 3He --> nu_mu + 3H is also analyzed, and the total capture rate is found to be 1494(15) s^{-1}, 1491(16) s^{-1}, 1488(18) s^{-1}, and 1475(16) s^{-1} for a_{nn}=-18.95 fm, -16.0 fm, -22.0 fm, and +18.22 fm, respectively. All the theoretical uncertainties are due to the fitting procedure and radiative corrections. Our results seem to exclude the possibility of constraining a negative a_{nn} with an uncertainty of less than ~ +/-3 fm through an accurate determination of the muon capture rates. However, a comparison with the already available experimental data discourages the possibility of a bound di-neutron state (positive a_{nn}).

L. E. Marcucci; R. Machleidt

2014-09-15

178

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

179

Measurement of the neutron-neutron scattering length using the ?-d capture reaction  

NASA Astrophysics Data System (ADS)

We have determined a value for the 1S0 neutron-neutron scattering length (ann) from high-precision measurements of time-of-flight spectra of neutrons from the H2(?-,n?)n capture reaction. The measurements were done at the Los Alamos Meson Physics Facility by the E1286 Collaboration. The high spatial resolution of our ?-ray detector enabled us to make a detailed assessment of the systematic uncertainties in our techniques. The value obtained in the present work is ann=-18.63±0.10 (statistical) ± 0.44 (systematic) ± 0.30 (theoretical) fm. This result is consistent with previous determinations of ann from the ?-d capture reaction. We found that the analysis of the data with calculations that use a relativistic phase-space factor gives a more negative value for ann by 0.33 fm over the analysis done using a nonrelativistic phase-space factor. Combining the present result with the previous ones from ?-d capture gives ann=-18.63±0.27(expt)±0.30 fm (theory). For the first time the combined statistical and systematic experimental uncertainty in ann is smaller than the theoretical uncertainty and comparable to the uncertainty in the proton-proton 1S0 scattering length (app). This average value of ann when corrected for the magnetic-moment interaction of the two neutrons becomes -18.9 ± 0.4 fm, which is 1.6 ± 0.5 fm different from the recommended value of app, thereby confirming charge symmetry breaking at the 1% confidence level.

Chen, Q.; Howell, C. R.; Carman, T. S.; Gibbs, W. R.; Gibson, B. F.; Hussein, A.; Kiser, M. R.; Mertens, G.; Moore, C. F.; Morris, C.; Obst, A.; Pasyuk, E.; Roper, C. D.; Salinas, F.; Setze, H. R.; Slaus, I.; Sterbenz, S.; Tornow, W.; Walter, R. L.; Whiteley, C. R.; Whitton, M.

2008-05-01

180

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

NASA Astrophysics Data System (ADS)

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

Matsuo, Masayuki

2013-07-01

181

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

182

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

PubMed

The 7Li(p,n)7Be reaction has been investigated as an accelerator-driven neutron source for proton energies between 2.1 and 2.6 MeV. Epithermal neutron beams shaped by three moderator materials, Al/AlF3, 7LiF, and D2O, have been analyzed and their usefulness for boron neutron capture therapy (BNCT) treatments evaluated. Radiation transport through the moderator assembly has been simulated with the Monte Carlo N-particle code (MCNP). Fluence and dose distributions in a head phantom were calculated using BNCT treatment planning software. Depth-dose distributions and treatment times were studied as a function of proton beam energy and moderator thickness. It was found that an accelerator-based neutron source with Al/AlF3 or 7LiF as moderator material can produce depth-dose distributions superior to those calculated for a previously published neutron beam design for the Brookhaven Medical Research Reactor, achieving up to approximately 50% higher doses near the midline of the brain. For a single beam treatment, a proton beam current of 20 mA, and a 7LiF moderator, the treatment time was estimated to be about 40 min. The tumor dose deposited at a depth of 8 cm was calculated to be about 21 Gy-Eq. PMID:9775379

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

1998-09-01

183

A comparison of the COG and MCNP codes in computational neutron capture therapy modeling, Part I: boron neutron capture therapy models.  

PubMed

The goal of this study was to evaluate the COG Monte Carlo radiation transport code, developed and tested by Lawrence Livermore National Laboratory, for neutron capture therapy related modeling. A boron neutron capture therapy model was analyzed comparing COG calculational results to results from the widely used MCNP4B (Monte Carlo N-Particle) transport code. The approach for computing neutron fluence rate and each dose component relevant in boron neutron capture therapy is described, and calculated values are shown in detail. The differences between the COG and MCNP predictions are qualified and quantified. The differences are generally small and suggest that the COG code can be applied for BNCT research related problems. PMID:16010123

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

2005-08-01

184

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

PubMed

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

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

1999-07-01

185

Muon capture on deuteron and the neutron-neutron scattering length  

E-print Network

The muon capture reaction mu + 2H --> nu_mu + n + n is studied with nuclear potentials and charge-changing weak currents, derived within chiral effective field theory. The next-to-next-to-next-to leading order (N3LO) chiral potential with cutoff parameter Lambda=500 MeV is used, but the low-energy constant (LEC) determining the neutron-neutron S-wave scattering length (a_{nn}) is varied so as to obtain four different values, which are a_{nn}=-18.95 fm, -16.0 fm, -22.0 fm, and +18.22 fm. The first value is the present empirical one, while the last one is chosen such as to lead to a di-neutron bound system with a binding energy of 139 keV. The LEC's c_D and c_E, present in the three-nucleon potential and axial-vector current (c_D), are constrained to reproduce the A=3 binding energies and the triton Gamow-Teller matrix element. The muon capture rate on the deuteron in the doublet hyperfine initial state is found to be 399(3) s^{-1} for a_{nn}=-18.95 and -16.0 fm; and 400(3) s^{-1} for a_{nn}=-22.0 fm. However, ...

Marcucci, L E

2014-01-01

186

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

187

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

NASA Astrophysics Data System (ADS)

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

Rivard, Mark Joseph

188

Accelerator based neutron source for neutron capture therapy B. Bayanov, Yu. Belchenko, V. Belov, V. Davydenko, A. Donin, A. Dranichnikov, A. Ivanov,  

E-print Network

Accelerator based neutron source for neutron capture therapy B. Bayanov, Yu. Belchenko, V. Belov, V of Physics and Power Engineering (Obninsk) have proposed an accelerator based neutron source for neutron accelerator (VITA) and near threshold 7 Li(p,n)7 Be neutron generation. Pilot accelerator based neutron source

Taskaev, Sergey Yur'evich

189

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

190

Comparison of statistical model calculations for stable isotope neutron capture  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

191

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

NASA Astrophysics Data System (ADS)

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

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

192

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

193

Neutron Capture Measurements at the Cern-Ntof Facility for ADS Applications  

Microsoft Academic Search

A new neutron time-of-flight facility has recently been constructed and become available at CERN. The high instantaneous neutron flux, high resolution and low background make this facility well suited for high quality neutron cross section measurements. The scientific programme of the nTOF collaboration include the measurements of neutron capture, fission and (n, xn) reaction cross sections for nuclear technology, nuclear

U. Abbondanno; G. Aerts; H. Alvarez; S. Andriamonje; A. Angelopoulos; P. Assimakopoulos; C. Bacri; G. Badurek; P. Baumann; F. Becvár; H. Beer; J. Benlliure; B. Berthier; E. Berthoumieux; S. Boffi; C. Borcea; E. Boscolo-Marchi; N. Bustreo; F. Calvino; D. Cano-Ott; R. Capote; P. Carlson; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; D. Cortina; A. Couture; J. Cox; S. Dababneh; M. Dahlfors; S. David; R. Dolfini; C. Domingo; I. Duran-Escribano; C. Eleftheriadis; M. Embid-Segura; L. Ferrant; A. Ferrari; L. Ferreira-Lourenco; R. Ferreiramarques; H. Frais-Koelbl; W. Furman; Y. Giomataris; I. Goncalves; E. Gonzalez-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; F. Gunsing; R. Haight; M. Heil; A. Herrera-Martinez; K. Ioannides; N. Janeva; E. Jericha; F. Käppeler; Y. Kadi; D. Karamanis; A. Kelic; V. Ketlerov; G. Kitis; P. Koehler; V. Konovalov; E. Kossionides; V. Lacoste; H. Leeb; A. Lindote; I. Lopes; M. Lozano; S. Lukic; S. Markov; S. Marrone; J. Martinez-Val; P. Mastinu; A. Mengoni; P. Milazzo; E. Minguez; A. Molina-Coballes; C. Moreau; F. Neves; H. Oberhummer; S. O'Brien; J. Pancin; C. Paradela; A. Pavlik; P. Pavlopoulos; A. Perez-Parra; J. Perlado; L. Perrot; V. Peskov; R. Plag; A. Plompen; A. Plukis; A. Poch; A. Policarpo; C. Pretel; J. Quesada; M. Radici; S. Raman; W. Rapp; R. Reifarth; F. Rejmund; M. Rosetti; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; E. Savvidis; C. Stephan; G. Tagliente; J. Tain; C. Tapia; L. Tassan-Got; L. Tavora; R. Terlizzi; M. Terrani; N. Tsangas; G. Vannini; P. Vaz; A. Ventura; D. Villamarin-Fernandez; M. Vincente-Vincente; V. Vlachoudis; R. Vlastou; F. Voss; H. Wendler; M. Wiescher; K. Wisshak; L. Zanini

2003-01-01

194

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

NASA Astrophysics Data System (ADS)

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

Dobelbower, Michael Christian

1997-07-01

195

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

196

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

PubMed

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 Li2CO3 powder (approximately 93% enriched isotopic 6Li) uniformly dispersed in polyethylene to a total 6Li content of 7.0 wt. %. The first collimator is 7.6 cm thick with a conical cavity 16 cm in diameter on the reactor core side tapering to 8 cm facing the patient's head. The second collimator is 15.2 cm thick with a conical cavity 20 cm in diameter tapering to 12 cm. A clinical trial of BNCT for patients with malignant brain tumors is underway using the first collimator. Results of phantom dosimetry and Monte Carlo computations indicate that the new 15.2 cm thick collimator will improve the neutron beam penetration. Thus, the second collimator was made and will be used in an upcoming clinical trial. In-air and in-phantom mixed-field dosimetric measurements were compared to Monte Carlo computations for both collimators. The deeper penetration is achieved but at a sacrifice in beam intensity. In this report, a performance comparison of both collimators regarding various fluence rate and absorbed dose distributions in a head model is presented and discussed. PMID:8994170

Liu, H B; Greenberg, D D; Capala, J; Wheeler, F J

1996-12-01

197

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

E-print Network

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

Danon, Yaron

198

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

199

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

NASA Astrophysics Data System (ADS)

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

Tymi?ska, Katarzyna

2007-01-01

200

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

SciTech Connect

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

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

2002-01-01

201

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

PubMed

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

Blue, Thomas E; Yanch, Jacquelyn C

2003-01-01

202

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

203

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

NASA Astrophysics Data System (ADS)

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

Bleuel, Darren Leo

204

Neutron Capture Cross Section Measurement of 151Sm at the CERN Neutron Time of Flight Facility (n_TOF)  

Microsoft Academic Search

The151Sm(n,gamma)152Sm cross section has been measured at the spallation neutron facility n_TOF at CERN in the energy range from 1eV to 1MeV. The new facility combines excellent resolution in neutron time-of-flight, low repetition rates, and an unsurpassed instantaneous luminosity, resulting in rather favorable signal\\/background ratios. The 151Sm cross section is of importance for characterizing neutron capture nucleosynthesis in asymptotic giant

U. Abbondanno; G. Aerts; F. Alvarez-Velarde; H. Álvarez-Pol; S. Andriamonje; J. Andrzejewski; G. Badurek; P. Baumann; F. Becvár; J. Benlliure; E. Berthoumieux; F. Calviño; D. Cano-Ott; R. Capote; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; D. Cortina; A. Couture; J. Cox; S. Dababneh; M. Dahlfors; S. David; R. Dolfini; C. Domingo-Pardo; I. Duran; M. Embid-Segura; L. Ferrant; A. Ferrari; R. Ferreira-Marques; H. Frais-Koelbl; W. Furman; I. Goncalves; R. Gallino; E. Gonzalez-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; F. Gunsing; B. Haas; R. Haight; M. Heil; A. Herrera-Martinez; S. Isaev; E. Jericha; F. Käppeler; Y. Kadi; D. Karadimos; M. Kerveno; V. Ketlerov; P. Koehler; V. Konovalov; M. Krticka; C. Lamboudis; H. Leeb; A. Lindote; I. Lopes; M. Lozano; S. Lukic; J. Marganiec; S. Marrone; J. Martinez-Val; P. Mastinu; A. Mengoni; P. M. Milazzo; A. Molina-Coballes; C. Moreau; M. Mosconi; F. Neves; H. Oberhummer; S. O'Brien; J. Pancin; T. Papaevangelou; C. Paradela; A. Pavlik; P. Pavlopoulos; J. M. Perlado; L. Perrot; M. Pignatari; R. Plag; A. Plompen; A. Plukis; A. Poch; A. Policarpo; C. Pretel; J. Quesada; S. Raman; W. Rapp; T. Rauscher; R. Reifarth; M. Rosetti; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; J. C. Soares; C. Stephan; G. Tagliente; J. Tain; L. Tassan-Got; L. Tavora; R. Terlizzi; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M. C. Vincente; V. Vlachoudis; F. Voss; H. Wendler; M. Wiescher; K. Wisshak

2004-01-01

205

(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

206

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

SciTech Connect

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

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

1982-01-01

207

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

E-print Network

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

Jiang, Hongyu, 1971-

2003-01-01

208

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

209

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

210

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

E-print Network

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

Chung, Yoonsun

2008-01-01

211

Investigation of elemental analysis using neutron-capture gamma ray spectra  

E-print Network

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

Hamawi, John Nicholas

1969-01-01

212

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

213

Neutron capture measurement on 173Lu at LANSCE with DANCE detector  

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

214

Folded-potential model calculation of low energy neutron direct-capture cross sections  

NASA Astrophysics Data System (ADS)

Low-energy neutron capture cross sections of 16O are obtained from the direct-capture model, using the folded potential calculated with the nuclear density distribution and the effective nucleon-nucleon interaction DDM3Y. As a result, it is found that the model calculations reproduce the observed cross sections excellently.

Kitazawa, Hideo; Igashira, Masayuki; Ohsaki, Toshiro

2000-07-01

215

Resonance Parameters and Uncertainties Derived from Epithermal Neutron Capture and Transmission Measurements of Natural Molybdenum  

E-print Network

Resonance Parameters and Uncertainties Derived from Epithermal Neutron Capture and Transmission capture and transmission measurements were performed by the time-of-flight technique. Resonance parameters were extracted from the data using the multilevel R-matrix Bayesian code SAMMY. A table of resonance

Danon, Yaron

216

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

SciTech Connect

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

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

2005-10-24

217

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

SciTech Connect

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

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

1997-12-31

218

Comment on Dark Matter Capture in Neutron Stars with Exotic Phases  

E-print Network

In this short paper, we argue the issue on dark matter capture in neutron stars. After summarizing the whole scenario and the introduction of previous studies along this line, we propose some potentially important effects due to the appearance of exotic phases such as neutron superfluidity, meson condensation and quark superconductivity. Those effects might be sizable and alter the previous results.

Motoi Tachibana; Marco Ruggieri

2013-12-20

219

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

NASA Astrophysics Data System (ADS)

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

Tyminska, Katarzyna

2008-01-01

220

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

NASA Astrophysics Data System (ADS)

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

Salehzadeh, Arash; Kirchner, Tom

2012-10-01

221

Nucleosynthesis by rapid neutron capture in the neutrino-energized wind from supernova cores  

Microsoft Academic Search

As a neutron star forms from the collapse of the iron core of a massive star, escaping neutrinos from the interior interact with material on the surface. This heated matter is then ejected as a baryon wind. As this slightly neutron-rich nucleon gas cools it experiences an alpha-rich freezeout to build A â¼100 seed nuclei which subsequently capture neutrons to

G. J. Mathews; J. R. Wilson; S. E. Woosley; R. D. Hoffman; B. S. Meyer

1993-01-01

222

THE UBIQUITY OF THE RAPID NEUTRON-CAPTURE PROCESS  

SciTech Connect

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

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

2010-12-01

223

Subshell Resolved Measurements of Single Electron Capture in Slow Ne7+-Helium Collisions  

NASA Astrophysics Data System (ADS)

Single electron capture in collisions of 9 keV/q Ne7+-ions with He has been studied using cold-target recoil-ion momentum spectroscopy (COLTRIMS). With an improved apparatus a longitudinal momentum resolution of 0.07 a.u. has been achieved. This momentum component corresponds to the binding energy of the active electron in the final state. For the first time state-resolved differential cross sections have been determined with respect to the main quantum number, subshell level and spin state of the captured electron.

Fischer, D.; Feuerstein, B.; Moshammer, R.; Crespo López-Urrutia, J. R.; Draganic, I.; Lörch, H.; Perumal, A. N.; Ullrich, J.; DuBois, R. D.

224

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

SciTech Connect

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

Belier, G.; Roig, O.; Daugas, J.-M.; Giarmana, O.; Meot, V.; Letourneau, A.; Marie, F.; Foucher, Y.; Aupiais, J.; Abt, D.; Jutier, Ch.; Le Petit, G.; Bettoni, C.; Gaudry, A.; Veyssiere, Ch.; Barat, E.; Dautremer, T.; Trama, J.-Ch. [CEA/DIF/DPTA Service de Physique Nucleaire, BP 12, F-91680 Bruyeres-le-Chatel (France); CEA/DSM/DAPNIA Service de Physique Nucleaire, CE Saclay, F-91191 Gif-sur-Yvette (France); CEA/DIF/DASE Service de Radioanalyse, Chimie et Environnement, BP 12, F-91680 Bruyeres-le-Chatel (France); CEA-CNRS Laboratoire Pierre Suee, CE Saclay, F-91191 Gif-sur-Yvette (France); CEA/DSM/DAPNIA Service Ingenierie des systemes, CE Saclay, F-91191 Gif-sur-Yvette (France); CEA/DRT/LIST/DETECS/SSTM/LETS, CE Saclay, F-91191 Gif-sur-Yvette (France)

2006-01-15

225

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

SciTech Connect

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

Alpizar-Vicente, A. M.; Hatarik, R. [Colorado School of Mines, Golden, C0 80401 (United States); Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bredeweg, T. A.; Esch, E.-I.; Haight, R. C.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Greife, U. [Colorado School of Mines, Golden, C0 80401 (United States)

2006-03-13

226

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

PubMed

Rheumatoid arthritis is one of the most common epidemic diseases in the world. For some patients, the treatment with steroids or nonsteroidal anti-inflammatory drugs is not effective, thus necessitating physical removal of the inflamed synovium. Alternative approaches other than surgery will provide appropriate disease control and improve the patient's quality of life. In this research, we evaluated the feasibility of conducting boron neutron capture synovectomy (BNCS) with the Tsing Hua open-pool reactor (THOR) as a neutron source. Monte Carlo simulations were performed with arthritic joint models and uncertainties were within 5%. The collimator, reflector and boron concentration were optimized to reduce the treatment time and normal tissue doses. For the knee joint, polyethylene with 40%-enriched Li(2)CO(3) was used as the collimator material, and a rear reflector of 15 cm thick graphite and side reflector of 10 cm thick graphite were chosen. The optimized treatment time was 5.4 min for the parallel-opposed irradiation. For the finger joint, polymethyl methacrylate was used as the reflector material. The treatment time can be reduced to 3.1 min, while skin and bone doses can be effectively reduced by approximately 9% compared with treatment using the graphite reflector. We conclude that using THOR as a treatment modality for BNCS could be a feasible alternative in clinical practice. PMID:17327660

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

2007-03-21

227

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

NASA Astrophysics Data System (ADS)

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.

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

2004-08-01

228

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

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

229

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

SciTech Connect

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

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

2005-10-04

230

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

231

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

232

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

E-print Network

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

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

2006-03-13

233

A new MCNPX 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

2011-02-16

234

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

E-print Network

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

Barth, Rolf F

235

Preparation of radioactive rare earth targets for neutron capture study  

Microsoft Academic Search

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

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

2002-01-01

236

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

SciTech Connect

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

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

1996-03-01

237

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

PubMed

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

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

2010-09-01

238

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

PubMed

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

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

2014-09-01

239

(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

240

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

241

Early clinical experience of boron neutron capture therapy for glioblastoma multiforme  

SciTech Connect

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

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

1995-12-31

242

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

PubMed Central

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

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

1997-01-01

243

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

SciTech Connect

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

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

1988-01-01

244

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

SciTech Connect

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

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

1988-01-01

245

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

246

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

247

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

248

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

249

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

SciTech Connect

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

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

2008-01-01

250

Hydrogen Electron Capture in Accreting Neutron Stars and the Resulting g-Mode Oscillation Spectrum  

E-print Network

We investigate hydrogen electron capture in the oceans of neutron stars accreting at rates appropriate for most Low-Mass X-Ray Binaries. These stars burn the accreted hydrogen and helium unstably in the upper atmosphere and accumulate material which usually contains some small amount of hydrogen (mass fractions are typically 10%) mixed in with the heavier iron group ashes. The subsequent evolution of this matter is determined by compression towards higher densities until electron capture on the hydrogen occurs. We construct steady-state models of the electron captures and the subsequent neutron recombinations onto the heavy nuclei. The density discontinuity from these captures gives rise to a new g-mode (much like a surface wave), which has a lowest order (l=1) frequency of 35 Hz when X=0.1 on a slowly rotating star. We also discuss, for the first time, a new set of non-radial g-modes unique to these neutron stars. These modes have most of their nodes in the finite thickness layer where the electron captures are occurring. The lowest order mode frequencies are in the 1-10 Hz range for a few radial nodes on a slowly rotating star. We conclude by discussing how the dispersion relations for these modes are modified for a rapidly rotating neutron star. Whether any of these modes are observable depends on their excitation and damping mechanisms and the ability to excite them, issues we will address in a future paper.

Lars Bildsten; Andrew Cumming

1998-07-01

251

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

NASA Astrophysics Data System (ADS)

For several low abundance stable nuclei, the thermal neutron capture cross sections are not well measured, while the cross sections for isotopes with high abundances are already well measured. Our experiments, different from the commonly used method of using gold foil as reference, are performed using natural foils for which we know the relative abundances of all isotopes and thermal neutron capture cross sections. Therefore, we can obtain the cross sections of low abundance isotopes, which are not known well, by comparing the yields of gammas from the neutron captures by various isotopes in the foils. The advantage of this method is the cancellation of potential systematic errors from thermal neutron flux, flux profile, foil thickness, foil size, and irradiation time. We have measured the thermal capture cross sections of 136Ce, 156Dy, and 168Yb isotopes, using the high thermal neutron flux from the reactor HANARO at KAERI, and have obtained new cross section values of 7.64±0.63 barn for 136Ce, 14.8±2.0 barn for 156Dy, and 1335±43 barn for 168Yb.

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

2014-05-01

252

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

253

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

254

Neutron capture on Zr94: Resonance parameters and Maxwellian-averaged cross sections  

Microsoft Academic Search

The neutron capture cross sections of the Zr isotopes play an important role in nucleosynthesis studies. The s-process reaction flow between the Fe seed and the heavier isotopes passes through the neutron magic nucleus Zr90 and through Zr91,92,93,94, but only part of the flow extends to Zr96 because of the branching point at Zr95. Apart from their effect on the

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

2011-01-01

255

Measurements of neutron capture cross-sections at n_TOF  

Microsoft Academic Search

Capture cross-sections on isotopes relevant to accelerator driven systems for energy production and nuclear waste transmutation, and to stellar nucleosynthesis have been studied at the innovative neutron time of flight facility n_TOF at CERN. The extremely high instantaneous neutron flux and the low background conditions in the experimental area make this facility unique for accurate measurements on low-mass or radioactive

G. Tagliente; U. Abbondanno; G. Aerts; F. Alvarez-Velarde; H. Álvarez-Pol; S. Andriamonje; J. Andrzejewski; G. Badurek; P. Baumann; F. Becvár; J. Benlliure; E. Berthoumieux; F. Calviño; D. Cano-Ott; R. Capote; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; D. Cortina; A. Couture; J. Cox; S. Dababneh; M. Dahlfors; S. David; R. Dolfini; C. Domingo-Pardo; I. Duran; M. Embid-Segura; L. Ferrant; A. Ferrari; R. Ferreira-Marques; H. Frais-Köelbl; W. Furman; I. Goncalves; R. Gallino; E. Gonzalez-Romero; A. Goverdovski; F. Gramegna; E. Griesmayer; F. Gunsing; B. Haas; R. Haight; M. Heil; A. Herrera-Martinez; S. Isaev; E. Jericha; F. Käppeler; Y. Kadi; D. Karadimos; M. Kerveno; V. Ketlerov; P. Koehler; V. Konovalov; C. Lamboudis; H. Leeb; A. Lindote; I. Lopes; G. Lorusso; M. Lozano; S. Lukic; J. Marganiec; S. Marrone; J. Martinez-Val; C. Massimi; P. Mastinu; A. Mengoni; P. M. Milazzo; A. Molina-Coballes; C. Moreau; M. Mosconi; F. Neves; H. Oberhummer; S. O'Brien; J. Pancin; T. Papaevangelou; C. Paradela; A. Pavlik; P. Pavlopoulos; J. M. Perlado; L. Perrot; M. Pignatari; R. Plag; A. Plompen; A. Plukis; A. Poch; A. Policarpo; C. Pretel; J. Quesada; W. Rapp; T. Rauscher; R. Reifarth; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; J. C. Soares; C. Stephan; J. L. Tain; L. Tassan-Got; L. Tavora; R. Terlizzi; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M. C. Vincente; V. Vlachoudis; F. Voss; H. Wendler; M. Wiescher; K. Wisshak

2007-01-01

256

Boron neutron capture therapy for papillary cystadenocarcinoma in the upper lip: a case report.  

PubMed

Boron neutron capture therapy (BNCT) is a tumor-selective radiation therapy using alpha and (7)Li particles, which are produced by the reaction of neutron with boron ((10)B), and taken up by the tumor. The authors report their first experience of BNCT on a patient with no history of surgery, chemotherapy or conventional radiotherapy for papillary cystadenocarcinoma in the upper lip. PMID:19179044

Kimura, Y; Ariyoshi, Y; Miyatake, S; Shimahara, M; Kawabata, S; Ono, K

2009-03-01

257

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

258

The n_TOF Total Absorption Calorimeter for neutron capture measurements at CERN  

SciTech Connect

The n{_}TOF Collaboration has built and commissioned a high-performance detector for (n,{gamma}) measurements called the Total Absorption Calorimeter (TAC). The TAC was especially designed for measuring neutron capture cross-sections of low-mass and/or radioactive samples with the accuracy required for nuclear technology and stellar nucleosynthesis. We present a detailed description of the TAC and discuss its overall performance in terms of energy and time resolution, background discrimination, detection efficiency and neutron sensitivity.

Guerrero, C. [Centro de Investigaciones Energeticas Medioambientales y Technol., Madrid, Spain; Koehler, Paul Edward [ORNL

2009-01-01

259

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

SciTech Connect

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

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

1990-08-01

260

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

NASA Astrophysics Data System (ADS)

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 4? barium fluoride detector. Several runs were performed under different experimental conditions to study the systematic uncertainties in detail. For the first time, data were recorded with an ADC system that allows one to register gamma-ray energy and time of flight of the individual detector modules. The cross-section ratios were determined with an overall uncertainty of ~1%. This is an improvement by about a factor of 5 compared to the existing data. Severe discrepancies were found with the results of previous measurements. Maxwellian-averaged neutron capture cross sections were calculated for thermal energies between kT=10 and 100 keV by normalizing the cross-section shape up to 700 keV neutron energy reported in literature to the present data. These stellar cross sections were used in an s-process analysis. The ratio of the values of the s-process current Ns (Maxwellian-averaged neutron capture cross section times s-process abundance) for the s-only isotopes 148,150Sm is 0.870+/-0.009 rather than unity as expected by the local approximation. The corresponding branching in the s-process path is analyzed in the framework of the classical approach. The resulting mean neutron density, nn=(3.8+/-0.6)×108 cm-3, is the most stringent value obtained so far. Finally the new cross sections are used to derive constraints for a stellar model and to check recently discovered isotopic anomalies in meteoritic samarium.

Wisshak, K.; Guber, K.; Voss, F.; Käppeler, F.; Reffo, G.

1993-09-01

261

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

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

262

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

PubMed

The HANARO neutron irradiation facility for various applications in the boron neutron capture therapy (BNCT) field was developed, and its characteristics were investigated. In order to obtain the sufficient thermal neutron flux with a low level of contamination by fast neutrons and gamma rays, a radiation filtering method was adopted. The radiation filter was designed by using a silicon single crystal, cooled by liquid nitrogen, and a bismuth crystal. The installation of the main components of the irradiation facility and the irradiation room was finished. Neutron beam characteristics were measured by using bare and cadmium-covered gold foils and wires. The in-phantom neutron flux distribution was measured for flux mapping inside the phantom. The gamma-ray dose was determined by using TLD-700 thermoluminescence dosimeters. The thermal and fast neutron fluxes and the gamma-ray dose were calculated by using the MCNP code, and they were compared with experimental data. The thermal neutron flux and Cd ratio available at this facility were confirmed to be 1.49 x 10(9) n cm(-2) s(-1) and 152, respectively. The maximum neutron flux inside the phantom was measured to be 2.79 x 10(9) n cm(-2) s(-1) at a depth of 3 mm in the phantom. The two-dimensional in-phantom neutron flux distribution was determined, and significant neutron irradiation was observed within 20 mm from the phantom surface. The gamma-ray dose rate for the free beam condition was expected to be about 80 cGy h(-1). These experimental results were reasonably well supported by calculation using the facility design code. This HANARO thermal neutron facility can be used not only for clinical trials, but also for various pre-clinical studies in the BNCT field. PMID:17440252

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

2007-05-01

263

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 Rosenschöld, Per; Lundqvist, Hans

2006-01-01

264

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

265

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

SciTech Connect

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

Gerald E. Tripard; Keith G. Fox

2006-08-24

266

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

PubMed

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

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

2014-10-01

267

Slow pulsating accreting neutron stars: the enigmatic case of 4U 2206+54  

NASA Astrophysics Data System (ADS)

The discovery of pulsations (Pspin=5500s) has solved the controversy on the nature of the compact object in the HMXB 4U2206+54 but has prompted new questions. According to spin evolutionary models such slow pulsations require the system to harbor a magnetar (B~1e14 G). However, the significant detection of a cyclotron resonant scattering feature at 30 keV implies a magnetic field B~3x1e12 G. Another unsolved question is whether the presence of a soft thermal component, representing emission from the polar caps, is present in all accreting pulsars. This proposal seeks to estimate the magnetic field strength through the neutron star spin evolution and investigate with unprecedented detail the soft energy spectrum of 4U2206+54 to check whether the polar cap scenario is applicable.

Reig, Pablo

2009-10-01

268

Testing T invariance in the interaction of slow neutrons with aligned nuclei  

NASA Astrophysics Data System (ADS)

The study of five-fold (P even, T odd) correlation in the interaction of slow polarized neutrons with aligned nuclei is a possible way of testing the time reversal invariance due to the expected enhancement of T violating effects in compound resonances. Possible nuclear targets are discussed which can be aligned both dynamically as well as by the 'brute force' method at low temperature. A statistical estimation is performed of the five-fold correlation for low lying p wave compound resonances of the 121Sb, 123Sb and 127I nuclei. It is shown that a significant improvement can be achieved for the bound on the intensity of the fundamental parity conserving time violating (PCTV) interaction.

Barabanov, A. L.; Beda, A. G.

2005-03-01

269

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

SciTech Connect

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

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

2002-08-18

270

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

E-print Network

A new measurement of the $\\theta_{13}$ mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of $\\theta_{13}$ measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GW$_{th}$ reactors, the rate deficit observed at the far hall is interpreted as $\\sin^22\\theta_{13}=0.083\\pm0.018$ in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain $\\sin^22\\theta_{13}=0.089\\pm0.008$ as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.

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

2014-01-01

271

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

E-print Network

A new measurement of the $\\theta_{13}$ mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of $\\theta_{13}$ measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GW$_{th}$ reactors, the rate deficit observed at the far hall is interpreted as $\\sin^22\\theta_{13}=0.083\\pm0.018$ in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain $\\sin^22\\theta_{13}=0.089\\pm0.008$ as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.

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

2014-06-25

272

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

NASA Astrophysics Data System (ADS)

A new measurement of the ?13 mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of the ?13 measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GWth reactors, the rate deficit observed at the far hall is interpreted as sin22?13=0.083±0.018 in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain sin22?13=0.089±0.008 as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.

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

2014-10-01

273

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

PubMed

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

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

2004-01-01

274

Neutron-capture Cross Sections from Indirect Measurements  

SciTech Connect

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

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

2011-10-18

275

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

276

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

277

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

PubMed

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

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

2014-09-18

278

Neutron-capture elements in the very metal-poor star HD122563  

E-print Network

We obtained high resolution, high S/N spectroscopy for the very metal-poor star HD122563 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 covering 3070 - 4780 A 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.

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

2006-02-06

279

Boron-Containing Nucleosides as Potential Delivery Agents for Neutron Capture Therapy of Brain Tumors  

Microsoft Academic Search

The purpose of the present study was to evaluate both in vitro and in vivo a series of boron-containing nucleosides that potentially could be used as delivery agents for neutron capture therapy. The rationale for their synthesis was based on the fact that proliferating neoplastic cells have increased requirements for nucleic acid precursors, and, therefore, they should preferentially localize in

Rolf F. Barth; Weilian Yang; Ashraf S. Al-Madhoun; Jayaseharan Johnsamuel; Youngjoo Byun; Subhash Chandra; Duane R. Smith; Werner Tjarks; Staffan Eriksson

2004-01-01

280

Astrophysical radiative neutron capture on 10B taking into account resonance at 475 keV  

E-print Network

The possibility of the description of the available experimental data for cross sections of the neutron capture reaction on 10B at thermal and astrophysical energies, taking into account the resonance at 475 keV, was considered within the framework of the modified potential cluster model with forbidden states and accounting for the resonance behavior of the scattering phase shifts.

Sergey Dubovichenko; Albert Dzhazairov-Kakhramanov

2013-12-17

281

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

SciTech Connect

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

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

2004-10-01

282

Neutron capture in 122,123,124Te: Critical test for s process studies  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 122,123,124,125,126Te 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 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? barium fluoride detector. Several sets of measurements were performed under different experimental conditions to study the systematic uncertainties in detail. The cross section ratios ?(Te)/?(Au) were determined with an overall uncertainty of ~1%. This is an improvement by about a factor of 5 compared to existing data. Maxwellian-averaged neutron capture cross sections were calculated for thermal energies between kT=10 and 100 keV by normalizing the cross section shape up to 600 keV neutron energy reported in literature to the present data. These stellar cross sections were used in an s process analysis. With the classical approach the abundances of the three s only isotopes 122,123,124Te could be reproduced within the experimental uncertainties of ~1%. The accuracy of the present data also allowed us to derive constraints for the existing stellar models with respect to the effective neutron density. Furthermore, the p process abundances for the tellurium isotopes are discussed.

Wisshak, K.; Voss, F.; Käppeler, F.; Reffo, G.

1992-05-01

283

Neutron capture in 122,123,124Te: a critical test for s-process studies.  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of 122,123,124,125,126Te 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 7Li(p, n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4? Barium Fluoride Detector. Several runs have been performed under different experimental conditions to study the systematic uncertainties in detail. The cross section ratios were determined with an overall uncertainty of ?1%. Maxwellian averaged neutron capture cross sections were calculated for thermal energies between kT = 10 and 100 keV by normalizing the cross section shape up to 600 keV neutron energy reported in literature to the present data. These stellar cross sections were used in an s-process analysis. With the classical approach the abundances of the three s-only isotopes 122,123,124Te could be reproduced within the experimental uncertainties of ?1%. The accuracy of the present data allowed also to derive constraints for the existing stellar models with respect to the effective neutron density. Furthermore, the p-process abundances for the tellurium isotopes are discussed.

Wisshak, K.; Voß, F.; Käppeler, F.; Reffo, G.

1991-11-01

284

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

285

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

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

286

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

SciTech Connect

Neptunium-237 is a major constituent of spent nuclear fuel. Estimates place the amount of 237Np bound for the Yucca Mountain high-level waste repository at 40 metric tons. The Department of Energy's Advanced Fuel Cycle Initiative program is evaluating methods for transmuting the actinide waste that will be generated by future operation of commercial nuclear power plants. The critical parameter that defines the transmutation efficiency of actinide isotopes is the neutron fission-to-capture ratio for the particular isotope in a given neutron spectrum. The calculation of transmutation efficiency therefore requires accurate fission and capture cross sections. Current 237Np evaluations available for transmuter system studies show significant discrepancies in both the fission and capture cross sections in the energy regions of interest. Herein we report on 237Np (n,{gamma}) measurements using the recently commissioned DANCE array.

Esch, E.-I.; Bond, E.M.; Bredeweg, T. A.; Glover, S. E.; Haight, R. C.; Kronenberg, A.; O'Donnell, J. M.; Pitcher, E. J.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wender, S. A.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, NM, 87544 (United States); Alpizar-Vicente, A.; Greife, U.; Hatarik, R. [Colorado School of Mines, Golden, Co 80401 (United States)

2005-05-24

287

?-ray cascade transitions in 112Cd and 114Cd following resonance capture of epithermal neutrons  

NASA Astrophysics Data System (ADS)

Cascades of ?-ray transitions in 112Cd and 114Cd have been studied in a neutron-capture experiment at the Los Alamos Neutron Science Center using a highly segmented and highly efficient ?-ray calorimeter—Detector for Advanced Neutron Capture Experiments. Intensity distributions of two-, three-, and multifold coincidence ?-ray transitions de-exciting resonances with known angular momenta and terminating at the ground state and at the first excited levels have been obtained. The results are compared with statistical-model calculations using the code dicebox for the two theoretical models of electric-dipole photon-strength functions, the standard Lorentzian and the model of Kadmenskii, Markushev, and Furman. It has been found that a combination of the two models reproduces the data best. Adding resonance structures, such as the scissors mode and the pygmy resonance, to the photon-strength function do not improve the description of the ?-ray spectra.

Rusev, G.; Jandel, M.; Krti?ka, M.; Bredeweg, T. A.; Couture, A.; Taddeucci, T. N.; Ullmann, J. L.

2013-05-01

288

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

289

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

NASA Astrophysics Data System (ADS)

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

Taylor, Courtney

2006-10-01

290

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

291

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

SciTech Connect

Neutron beams are designed for capture therapy based on p-Li and p-Sc reactions using the Argonne Continuous Wave Linac (ACWL). The p-Li beam will provide a 2.5 {times} 10{sup 9} n/cm{sup 2}s epithermal flux with 7 {times} 10{sup 5} {gamma}/cm{sup 2}s contamination. On a human brain phantom, this beam allows an advantage depth (AD) of 10 cm, an advantage depth dose rate (ADDR) of 78 cGy/min and an advantage ratio (AR) of 3.2. The p-Sc beam offers 5.9 {times} 10{sup 7} n/cm{sup 2}s and a dose performance of AD = 8 cm and AR = 3.5, suggesting the potential of near-threshold (p,n) reactions such as the p-Li reaction at E{sub p} = 1.92 MeV. A thermal radiography beam could also be obtained from ACWL.

Zhou, X.L. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Nuclear Engineering; McMichael, G.E. [Argonne National Lab., Idaho Falls, ID (United States). Technology Development Div.

1994-10-01

292

Low-lying dipole response in the Relativistic Quasiparticle Time Blocking Approximation and its influence on neutron capture cross sections  

E-print Network

We have computed dipole strength distributions for nickel and tin isotopes within the Relativistic Quasiparticle Time Blocking approximation (RQTBA). These calculations provide a good description of data, including the neutron-rich tin isotopes $^{130,132}$Sn. The resulting dipole strengths have been implemented in Hauser-Feshbach calculations of astrophysical neutron capture rates relevant for r-process nucleosynthesis studies. The RQTBA calculations show the presence of enhanced dipole strength at energies around the neutron threshold for neutron rich nuclei. The computed neutron capture rates are sensitive to the fine structure of the low lying dipole strength, which emphasizes the importance of a reliable knowledge of this excitation mode.

E. Litvinova; H. P. Loens; K. Langanke; G. Martinez-Pinedo; T. Rauscher; P. Ring; F. -K. Thielemann; V. Tselyaev

2009-03-31

293

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

NASA Astrophysics Data System (ADS)

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

Sakurai, Yoshinori; Ono, Koji

2007-12-01

294

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

295

[Epithermal neutron capture therapy]. Progress and status report  

SciTech Connect

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

Not Available

1993-05-01

296

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

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

297

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

PubMed

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

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

2004-09-21

298

Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium  

SciTech Connect

The purpose of the present work is to accurately measure the neutron cross sections of samarium. The most significant isotope is {sup 149}Sm, which has a large neutron absorption cross section at thermal energies and is a {sup 235}U fission product with a 1% yield. Its cross sections are thus of concern to reactor neutronics. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic institute (RPI) LINAC facility using metallic and liquid Sm samples. The capture measurements were made at the 25 meter flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-meter flight stations with {sup 6}Li glass scintillation detectors. Resonance parameters were determined by a combined analysis of six experiments (three capture and three transmission) using the multi-level R-matrix Bayesian code SAMMY version M2. The significant features of this work are as follows. Dilute samples of samarium nitrate in deuterated water (D{sub 2}O) were prepared to measure the strong resonances at 0.1 and 8 eV without saturation. Disk-shaped spectroscopic quartz cells were obtained with parallel inner surfaces to provide a uniform thickness of solution. The diluent feature of the SAMMY program was used to analyze these data. The SAMMY program also includes multiple scattering corrections to capture yield data and resolution functions specific to the RPI facility. Resonance parameters for all stable isotopes of samarium were deduced for all resonances up to 30 eV. Thermal capture cross-section and capture resonance integral calculations were made using the resultant resonance parameters and were compared to results obtained using resonance parameters from ENDF/B-VI updated through release 3. Extending the definition of the capture resonance integral to include the strong 0.1 eV resonance in {sup 149}Sm, present measurements agree within estimated uncertainties with EnDF/B-VI release 3. The thermal capture cross-section was calculated from the present measurements of the resonance parameters and also agrees with ENDF within estimated uncertainties. The present measurements reduce the statistical uncertainties in resonance parameters compared to prior measurements.

G. Leinweber; J.A. Burke; H.D. Knox; N.J. Drindak; D.W. Mesh; W.T. Haines; R.V. Ballad; R.C. Block; R.E. Slovacek; C.J. Werner; M.J. Trbovich; D.P. Barry; T. Sato

2001-07-16

299

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

NASA Astrophysics Data System (ADS)

A neutron beam simulation study is carried out to determine the most suitable neutron energy for treatment of shallow and deep-seated brain tumors in the context of Boron Neutron Capture Therapy (BNCT). Two figures-of-merit, the therapeutic gain and the neutron fluence are utilized as beam assessment parameters. An irradiation cavity is used instead of a parallel beam port for the therapy. Calculations are performed using the MCNP5 code. After the optimization of our beam-shaper a study of the dose distribution in the head, neck, tyroids, lungs and upper and middle spine had been made. The therapeutic gain is increased while the current required for one hour treatment is decreased in comparison with the trading prototypes of NG used for BNCT

Cabal, F. Padilla; Martín, G.

2008-08-01

300

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.

301

New concepts for compact accelerator/target for Boron Neutron Capture Therapy  

NASA Astrophysics Data System (ADS)

Two new target concepts, NIFTI and DISCOS, that enable a large reduction in the proton beam current needed to produce epithermal neutrons for BNCT (Boron Neutron Capture Therapy) are described. In the NIFTI concept, high energy neutrons produced by (p,n) reactions of 2.5 MeV protons on Li are down scattered to treatment energies (˜20 keV) by relatively thin layers of PbF2 and iron. In the DISCOS concept, treatment energy neutrons are produced directly in a succession of thin (˜1 micron) liquid Li films on rotating Be foils. These foils interact with a proton beam that operates just above threshold for the (p,n) reaction, with an applied DC field to re-accelerate the proton beam between the target foils.

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

1997-02-01

302

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

303

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

304

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

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of the radioactive isotope 151Sm 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 7Li(p,n)7Be reaction by bombarding metallic Li targets with a pulsed proton beam and capture events were registered with the Karlsruhe 4? 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 151Sm. Over most of the measured energy range uncertainties of ~2 3% could be achieved for the 151Sm/197Au ratio. Maxwellian averaged neutron capture cross sections of 151Sm 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 151Sm. 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 152Gd and a few other cases is discussed.

Wisshak, K.; Voss, F.; Käppeler, F.; Krti?ka, M.; Raman, S.; Mengoni, A.; Gallino, R.

2006-01-01

305

Resonance neutron-capture cross sections of stable magnesium isotopes and their astrophysical implications  

SciTech Connect

We have measured the neutron capture cross sections of the stable magnesium isotopes {sup 24,25,26}Mg in the energy range of interest to the s process using the neutron time-of-flight facility n{_}TOF at CERN. Capture events from a natural metal sample and from samples enriched in {sup 25}Mg and {sup 26}Mg were recorded using the total energy method based on C{sub 6}{sup 2}H{sub 6} detectors. Neutron resonance parameters were extracted by a simultaneous resonance shape analysis of the present capture data and existing transmission data on a natural isotopic sample. Maxwellian-averaged capture cross sections for the three isotopes were calculated up to thermal energies of 100 keV and their impact on s-process analyses was investigated. At 30 keV the new values of the stellar cross section for {sup 24}Mg, {sup 25}Mg, and {sup 26}Mg are 3.8 {+-} 0.2 mb, 4.1 {+-} 0.6 mb, and 0.14 {+-} 0.01 mb, respectively.

Pigni, Marco T [ORNL; Massimi, C. [Universita di Bologna; Vannini, G. [Universita di Bologna; Koehler, Paul [ORNL; Bisterzo, S. [University of Turin, Turin, Italy; Gallino, R. [University of Turin, Turin, Italy; Colonna, N. [Instituto Nazionale di Fisica Nucleare, Bari, Italy; Lorusso, G. [1st Nazl Fis Nucl, Bari, Italy; Barbagallo, M. [Instituto Nazionale di Fisica Nucleare, Bari, Italy; Marrone, S. [Instituto Nazionale di Fisica Nucleare, Bari, Italy; Tagliente, G. [Instituto Nazionale di Fisica Nucleare, Bari, Italy; Terlizzi, R. [Instituto Nazionale di Fisica Nucleare, Bari, Italy; Gunsing, F. [CEA, Saclay, France; Aerts, G. [CEA, Saclay, France; Andriamonje, S. [CEA, Saclay, France; Berthoumieux, E. [CEA, Saclay, France; Carrapico, C. [CEA, Saclay, France; Dridi, W. [CEA, Saclay, France; Lampoudis, C. [CEA, Saclay, France; Pancin, J. [CEA, Saclay, France; Perrot, L. [CEA, Saclay, France; Plukis, A. [CEA, Saclay, France; Kaeppeler, K. [Institut fur Kernphysik, Karlsruhe, Germany; Dillmann, I. [Institut fur Kernphysik, Karlsruhe, Germany; Mosconi, M. [Karlsruhe Institute of Technology, Karlsruhe, Germany; Plag, R. [Institut fur Kernphysik, Karlsruhe, Germany; Voss, F. [Institut fur Kernphysik, Karlsruhe, Germany; Walter, S. [Institut fur Kernphysik, Karlsruhe, Germany; Wisshak, K. [Institut fur Kernphysik, Karlsruhe, Germany; Mengoni, A. [International Atomic Energy Agency (IAEA); Capote, R. [International Atomic Energy Agency (IAEA); Frais-Koelbl, H. [International Atomic Energy Agency (IAEA); Griesmayer, E. [International Atomic Energy Agency (IAEA); Mengoni, A. [CERN, Geneva, Switzerland; Calviani, M. [CERN, Geneva, Switzerland; Cennini, P. [CERN, Geneva, Switzerland; Chiaveri, E. [CERN, Geneva, Switzerland; Dahlfors, M. [CERN, Geneva, Switzerland; Ferrari, A. [CERN, Geneva, Switzerland; Fitzpatrick, L. [CERN, Geneva, Switzerland; Herrera-Martinez, A. [CERN, Geneva, Switzerland; Kadi, Y. [CERN, Geneva, Switzerland; Losito, R. [CERN, Geneva, Switzerland; Sarchiapone, L. [CERN, Geneva, Switzerland; Vlachoudis, V. [CERN, Geneva, Switzerland; Wendler, H. [CERN, Geneva, Switzerland; Pignatari, M. [Universitat Basel, Switzerland; Rauscher, T. [Universitat Basel, Switzerland; Abbondanno, U. [Instituto Nazionale de Fisica Nucleare, Trieste, Italy; Belloni, F. [Instituto Nazionale de Fisica Nucleare, Trieste, Italy; Fujii, K. [Instituto Nazionale de Fisica Nucleare, Trieste, Italy; Milazzo, P. M. [Instituto Nazionale de Fisica Nucleare, Trieste, Italy; Moreau, C. [Instituto Nazionale de Fisica Nucleare, Trieste, Italy; Alvarez, H. [University of Santiago de Compostela, Spain; Duran, I. [Universidad de Santiago de Compostela; Paradela, C. [University of Santiago de Compostela, Spain; Tarrio, D. [University of Santiago de Compostela, Spain; Alvarez-Velarde, F. [Centro de Investigaciones Energeticas Medioambientales y Technol., Madrid, Spain; Cano-Ott, D. [CIEMAT, Madrid; Embid-Segura, M. [Centro de Investigaciones Energeticas Medioambientales y Technol., Madrid, Spain; Gonzalez-Romero, E. [CIEMAT, Madrid; Guerrero, C. [Centro de Investigaciones Energeticas Medioambientales y Technol., Madrid, Spain; Martinez, T. [Centro de Investigaciones Energeticas Medioambientales y Technol., Madrid, Spain; Mendoza, E. [Centro de Investigaciones Energeticas Medioambientales y Technol., Madrid, Spain; Villamarin, D. [Centro de Investigaciones Energeticas Medioambientales y Technol., Madrid, Spain; Andrzejewski, J. [University of Lodz, Lodz, Poland; Marganiec, J. [University of Lodz; Assimakopoulos, P. A. [University of Ioannina, Greece; Karadimos, D. [University of Ioannina, Greece; Karamanis, D. [University of Ioannina, Greece; Papachristodoulou, C. [University of Ioannina, Greece; Patronis, N. [University of Ioannina, Greece; Audouin, L. [Universite Paris XI, Orsay, France; et al.

2012-01-01

306

A simple method for the analysis of neutron resonance capture spectra  

SciTech Connect

Neutron resonance capture analysis (NRCA) is a method used to determine the bulk composition of various kinds of objects and materials. It is based on analyzing direct capture resonance peaks. However, the analysis is complicated by scattering followed by capture effects in the object itself. These effects depend on the object's shape and size. In this paper the new Delft elemental analysis program (DEAP) is presented which can automatically and quickly analyze multiple NRCA spectra in a practical and simple way, yielding the elemental bulk composition of an object, largely independent of its shape and size. The DEAP method is demonstrated with data obtained with a Roman bronze water tap excavated in Nijmegen (The Netherlands). DEAP will also be used in the framework of the Ancient Charm project as data analysis program for neutron resonance capture imaging (NRCI) experiments. NRCI provides three-dimensional visualization and quantification of the internal structure of archaeological objects by performing scanning measurements with narrowly collimated neutron beams on archaeological objects in computed tomography based experimental setups. The large amounts (hundreds to thousands) of spectra produced during a NRCI experiment can automatically and quickly be analyzed by DEAP.

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

2009-03-15

307

Study of moderator thickness for an accelerator-based neutron irradiation facility for boron neutron capture therapy using the 7Li(p, n) reaction near threshold  

Microsoft Academic Search

Accelerator neutron sources for epithermal neutron capture therapy utilizing the 7 Li(p, n) nuclear reaction will require a moderator even in the threshold range of 1.89 to 1.95 MeV. The corresponding neutron energies allow for a thinner reflector and moderator, with less reduction of the epithermal flux. To estimate the useful neutron flux within the epithermal range (4 eV-40 keV),

Sergei Zimin; Barry J. Allen

2000-01-01

308

The effects of boron neutron capture irradiation on oral mucosa: evaluation using a rat tongue model.  

PubMed

The ventral surface of the tongue of male Fisher 344 rats was used to evaluate the response of oral mucosa to boron neutron capture irradiation. Three hours after i.p. injection of 700 mg/kg of the boron delivery agent p-boronophenylalanine (BPA), the boron concentrations in blood and tongue mucosal epithelium were approximately 21 and 23 microgram (10)B/g, respectively. The doses required to produce a 50% incidence of ulceration with X rays, the Brookhaven Medical Research Reactor thermal neutron beam alone, or the thermal neutron beam in the presence of BPA were 13.4 +/- 0.2, 4. 2 +/- 0.1, and 3.0 +/- 0.1 Gy, respectively. Ulceration of the tongue was evident by 6 to 7 days after irradiation, irrespective of the irradiation modality; healing was related to dose and was relatively rapid (neutron beam and 4.9 for the products of the boron neutron capture reaction, (10)B(n,alpha)(7)Li. Oral mucosa is highly sensitive to BPA-mediated BNC irradiation and could be a dose-limiting normal tissue in BNCT of brain tumors, or if BPA-based BNCT is applied to the treatment of head and neck tumors. PMID:10409319

Coderre, J A; Morris, G M; Kalef-Ezra, J; Micca, P L; Ma, R; Youngs, K; Gordon, C R

1999-08-01

309

Evaluation of an iron-filtered epithermal neutron beam for neutron-capture therapy.  

PubMed

An epithermal neutron filter using iron, aluminum, and sulfur was evaluated to determine if the therapeutic performance could be improved with respect to aluminum-sulfur-based filters. An empirically optimized filter was developed that delivered a 93% pure beam of 24-keV epithermal neutrons. It was expected that a thick filter using iron with a density thickness greater than 200 g/cm2 would eliminate the excess gamma contamination found in Al-S filters. This research showed that prompt gamma production from neutron interactions in iron was the dominant dose component. Dosimetric parameters of the beam were determined from the measurement of absorbed dose in air, thermal neutron flux in a head phantom, neutron and gamma spectroscopy, and microdosimetry. PMID:1656179

Musolino, S V; McGinley, P H; Greenwood, R C; Kliauga, P; Fairchild, R G

1991-01-01

310

Evaluation of an iron-filtered epithermal neutron beam for neutron-capture therapy  

SciTech Connect

An epithermal neutron filter using iron, aluminum, and sulfur was evaluated to determine if the therapeutic performance could be improved with respect to aluminum--sulfur-based filters. An empirically optimized filter was developed that delivered a 93% pure beam of 24-keV epithermal neutrons. It was expected that a thick filter using iron with a density thickness {gt}200 g/cm{sup 2} would eliminate the excess gamma contamination found in Al--S filters. This research showed that prompt gamma production from neutron interactions in iron was the dominant dose component. Dosimetric parameters of the beam were determined from the measurement of absorbed dose in air, thermal neutron flux in a head phantom, neutron and gamma spectroscopy, and microdosimetry.

Musolino, S.V. (Safety and Environmental Protection Division, Brookhaven National Laboratory, Upton, NY (USA)); McGinley, P.H. (Nuclear Engineering and Health Physics, Georgia Institute of Technology, Atlanta, GA (USA)); Greenwood, R.C. (Idaho National Engineering Laboratory, P.O. Box 1625, Idaho Falls, ID (USA)); Kliauga, P. (College of Physicians and Surgeons, Columbia University, 630 West 168th Street NY (USA)); Fairchild, R.G. (Medical Department, Brookhaven National Laboratory, Upton, NY (USA))

1991-07-01

311

Measurements of neutron capture cross-sections at n{sub T}OF  

SciTech Connect

Capture cross-sections on isotopes relevant to accelerator driven systems for energy production and nuclear waste transmutation, and to stellar nucleosynthesis have been studied at the innovative neutron time of flight facility n{sub T}OF at CERN. The extremely high instantaneous neutron flux and the low background conditions in the experimental area make this facility unique for accurate measurements on low-mass or radioactive samples. The n{sub T}OF facility is described, together with the features of the experimental apparata used. First results of the experimental campaign 2002-2004 are presented.

Tagliente, G.; Colonna, N.; Lorusso, G.; Marrone, S.; Terlizzi, R. [INFN, Bari (Italy); Abbondanno, U.; Milazzo, P. M.; Moreau, C. [INFN, Trieste (Italy); Aerts, G.; Andriamonje, S.; Berthoumieux, E.; Gunsing, F.; Pancin, J.; Perrot, L.; Plukis, A. [CEA/Saclay - DSM (France); Alvarez-Velarde, F.; Cano-Ott, D.; Embid-Segura, M.; Gonzalez-Romero, E.; Villamarin, D. [CIEMAT (Spain)] (and others)

2007-02-12

312

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

NASA Astrophysics Data System (ADS)

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

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

2007-02-01

313

Thermal Neutron Capture and Thermal Neutron Burn-up of K isomeric state of 177mLu: a way to the Neutron Super-Elastic Scattering cross section  

SciTech Connect

Thermal neutron radiative capture and burn-up measurements of the K isomeric state in 177Lu form part of an original method to indirectly obtain the neutron super-elastic scattering cross section at thermal energy. Neutron super-elastic scattering, also called neutron inelastic acceleration, occurs during the neutron collisions with an excited nuclear level. In this reaction, the nucleus could partly transfer its excitation energy to the scattered neutron.

Roig, O.; Belier, G.; Meot, V.; Daugas, J.-M.; Romain, P. [CEA/DIF/DPTA Service de Physique Nucleaire, BP 12, 91680 Bruyeres-le-Chatel (France); Aupiais, J.; Jutier, Ch.; Le Petit, G. [CEA/DIF/DASE Service de Radio-analyse, Chimie et Environnement, BP 12, 91680 Bruyeres-le-Chatel (France); Letourneau, A.; Marie, F. [CEA/DSM/DAPNIA Service de Physique Nucleaire, CE Saclay, 91191 Gif-sur-Yvette (France); Veyssiere, Ch. [CEA/DSM/DAPNIA Service d'Ingenierie des Systemes, CE Saclay, 91191 Gif sur Yvette (France)

2006-03-13

314

Parity nonconservation in (106)Pd, (108)Pd and (238)U using neutron-transmission and neutron-capture techniques  

NASA Astrophysics Data System (ADS)

Measurements were made of the parity-nonconserving (PNC), helicity-dependent neutron resonance cross sections for epithermal neutrons incident on 106Pd,/ 108Pd and 238U. By reversing the spin direction of longitudinally polarized, epithermal neutrons produced at the Manuel Lujan Neutron Scattering Center in Los Alamos, the longitudinal cross section asymmetry was measured using neutron-transmission (238U) and neutron-capture (106Pd and 108Pd) techniques. The experiments employed a dynamically polarized proton target to polarize the neutrons and a magnetic neutron-spin flipper. In transmission the neutrons were detected by a 55-element 10B-loaded liquid scintillator. The capture experiment used 24 CsI crystals to detect the neutron- capture ?-rays, a spin-transport system and a neutron polarimeter. In addition to extracting cross section asymmetries, neutron resonance parameters were determined for 12 s-waves and 16 p-waves in 106Pd (60-1900 eV); 9 s-waves and 21 p-waves in 108Pd (100-2300 eV); and 13 s-waves and 24 p-waves in 238U (6-300 eV). In the analysis of experiments of this type, the compound nucleus is treated statistically and the PNC asymmetries are expected to be randomly distributed about zero. The width of the distribution of asymmetries in a given nucleus is related to the root-mean-squared PNC matrix element, [/cal M]. In order to compare the strength of the weak interaction in different nuclei, a spreading width, ? W, can be calculated from [/cal M] for each nucleus. Six resonances in 238U showed effects, three positive and three negative, giving [/cal M]=0.67- 0.16+0.24 meV and ? W=(1.35- 0.64+0.97)× 10-7 eV. One negative PNC effect was seen in 106Pd at 593.4 eV. However, the effect is most likely due to a p-wave that is unresolved from the s-wave at 593.4 eV. If this is true, the lack of p-wave resonance information prohibits further analysis. If the 593.4 eV resonance is in fact a p-wave, then the analysis gives [/cal M]=11.0-4.5+7.7 meV and ? W=(48-39+67)× 10-7 eV. Further experimentation is required to resolve this issue. No effects were seen in 108Pd which leads to [/cal M]<4.2 meV and ? W<7.0× 10-7 eV.

Crawford, Bret Edward

315

The Influence Of Neutron Capture Rates On The Rare Earth Region Of The r-Process Abundance Pattern  

E-print Network

We study the sensitivity of the r-process abundance pattern to neutron capture rates along the rare earth region (A~150 to A~180). We introduce the concepts of large nuclear flow and flow saturation which determine the neutron capture rates that are influential in setting the rare earth abundances. We illustrate the value of the two concepts by considering high entropy conditions favorable for rare earth peak production and identifying important neutron capture rates among the rare earth isotopes. We also show how these rates influence nuclear flow and specific sections of the abundance pattern.

M. R. Mumpower; G. C. McLaughlin; R. A. Surman

2012-04-02

316

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

SciTech Connect

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

Ma Yunzhi; Geng Jinpeng; Gao Song; Bao Shanglian [Research Center for Tumor Diagnosis and Radiotherapy Physics and Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871 (China); Department of Nuclear Physics, Chinese Institute of Atomic Energy, Beijing, 102413 (China); Research Center for Tumor Diagnosis and Radiotherapy Physics and Laboratory of Medical Physics and Engineering, Peking University, Beijing 100871 (China)

2006-12-15

317

A neutron source to measure stellar neutron capture cross sections at kT=5 keV  

NASA Astrophysics Data System (ADS)

Since 1980 the 7Li(p,n)7Be reaction was intensively used for activation measurements. With a proton energy of E=1911 keV the resulting neutron spectrum resembles a Maxwell-Boltzmann distribution with a thermal energy of kT=25 keV. Therefore, this neutron source is ideal to determine Maxwellian-averaged neutron capture cross sections (MACS) close to a temperature of 250 million Kelvin (kT=23 keV) which is typical for the s process in red giant stars. Meanwhile, detailed stellar models indicate that the dominant neutron exposure of the main s-process component in low mass AGB stars occurs at a lower temperature of 90 million Kelvin (kT=8 keV). Hence, the necessary stellar reaction rates had to be extrapolated from 25 keV to the lower thermal energy. In order to avoid the corresponding additional uncertainties, we report on the 18O(p,n)18F neutron source, which allows one to produce a Maxwell-Boltzmann spectrum close to the lower thermal energy of kT=8 keV. First results of activation measurements for 138Ba(n,?)139Ba, 139La(n,?)140La, and 175Lu(n,?)176Lum will be presented.

Heil, M.; Dababneh, S.; Käppeler, F.; Plag, R.; Juseviciute, A.; Winckler, N.; Reifarth, R.; O'Brien, S.

2005-07-01

318

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

319

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

NASA Astrophysics Data System (ADS)

A tomographic system for online dose measurements in Boron Neutron Capture Therapy (BNCT) based on the measurement of a specific 478 keV ?-ray emitted after the neutron capture in boron is being developed. In the present work we study by means of Monte Carlo numerical simulations the effects of the finite spatial resolution and the limited number of counts, i. e. the statistical noise, on the reconstructed image contrast of numerical phantoms. These phantoms, of simple geometry, mimic the tumor (specific) and the normal tissue (non specific) boron concentrations. The simulated projection data were reconstructed using the expectation-maximization maximum-likelihood algorithm. These studies will help in the improvement of BNCT dosimetry.

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

2007-02-01

320

238U Neutron Capture Cross Section Measurements at the GELINA Facility  

NASA Astrophysics Data System (ADS)

A set of neutron capture experiments based on the time-of-flight technique were performed in order to determine the 238U capture cross section in the unresolved resonance region. 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 uranium sample. The analysis of the experimental data is based on the total energy principle applied in combination with the pulse height weighting technique. The experimental details along with the analysis process are described. The first results in the resolved resonance region are presented and their validity provide a solid base to extend the analysis and extract the average cross section in the keV region.

Lampoudis, C.; Kopecky, S.; Becker, B.; Gunsing, F.; Schillebeeckx, P.; Wynants, R.

2014-05-01

321

The n_TOF Total Absorption Calorimeter for neutron capture measurements at CERN  

Microsoft Academic Search

The n_TOF Collaboration has built and commissioned a high-performance detector for (n,?) measurements called the Total Absorption Calorimeter (TAC). The TAC was especially designed for measuring neutron capture cross-sections of low-mass and\\/or radioactive samples with the accuracy required for nuclear technology and stellar nucleosynthesis. We present a detailed description of the TAC and discuss its overall performance in terms of

C. Guerrero; U. Abbondanno; G. Aerts; H. Álvarez; F. Álvarez-Velarde; S. Andriamonje; J. Andrzejewski; P. Assimakopoulos; L. Audouin; G. Badurek; P. Baumann; F. Becvár; E. Berthoumieux; F. Calviño; M. Calviani; D. Cano-Ott; R. Capote; C. Carrapiço; P. Cennini; V. Chepel; E. Chiaveri; N. Colonna; G. Cortes; A. Couture; J. Cox; M. Dahlfors; S. David; I. Dillmann; C. Domingo-Pardo; W. Dridi; I. Duran; C. Eleftheriadis; L. Ferrant; A. Ferrari; R. Ferreira-Marques; K. Fujii; W. Furman; I. Goncalves; E. González-Romero; F. Gramegna; F. Gunsing; B. Haas; R. Haight; M. Heil; A. Herrera-Martinez; M. Igashira; E. Jericha; F. Käppeler; Y. Kadi; D. Karadimos; M. Kerveno; P. Koehler; E. Kossionides; M. Krticka; C. Lampoudis; H. Leeb; A. Lindote; I. Lopes; M. Lozano; S. Lukic; J. Marganiec; S. Marrone; T. Martínez; C. Massimi; P. Mastinu; E. Mendoza; A. Mengoni; P. M. Milazzo; C. Moreau; M. Mosconi; F. Neves; H. Oberhummer; S. O’Brien; J. Pancin; C. Papachristodoulou; C. Papadopoulos; C. Paradela; N. Patronis; A. Pavlik; P. Pavlopoulos; L. Perrot; M. T. Pigni; R. Plag; A. Plompen; A. Plukis; A. Poch; J. Praena; C. Pretel; J. Quesada; T. Rauscher; R. Reifarth; C. Rubbia; G. Rudolf; P. Rullhusen; J. Salgado; C. Santos; L. Sarchiapone; I. Savvidis; C. Stephan; G. Tagliente; J. L. Tain; L. Tassan-Got; L. Tavora; R. Terlizzi; G. Vannini; P. Vaz; A. Ventura; D. Villamarin; M. C. Vicente; V. Vlachoudis; R. Vlastou; F. Voss; S. Walter; M. Wiescher; K. Wisshak

2009-01-01

322

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

323

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

324

The calculation of neutron capture gamma-ray yields for space shielding applications  

NASA Technical Reports Server (NTRS)

The application of nuclear models to the calculation of neutron capture and inelastic scattering gamma yields is discussed. The gamma ray cascade model describes the cascade process in terms of parameters which either: (1) embody statistical assumptions regarding electric and magnetic multipole transition strengths, level densities, and spin and parity distributions or (2) are fixed by experiment such as measured energies, spin and parity values, and transition probabilities for low lying states.

Yost, K. J.

1972-01-01

325

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

Microsoft Academic Search

Purpose: To analyze the possible increase in efficacy of boron neutron capture therapy (BNCT) for undifferentiated thyroid carcinoma (UTC) by using p-boronophenylalanine (BPA) plus 2,4-bis (,-dihydroxyethyl)-deutero-porphyrin IX (BOPP) and BPA plus nicotinamide (NA) as a radiosensitizer of the BNCT reaction. Methods and Materials: Nude mice were transplanted with a human UTC cell line (ARO), and after 15 days they were

Maria Alejandra Dagrosa; Lisa M. Sc. Thomasz; Juan Longhino; Marina Perona; Osvaldo Calzetta; Herman Blaumann; Raúl Jiménez Rebagliati; Romulo Cabrini; Steven Kahl; Guillermo Juan Juvenal; Mario Alberto Pisarev

2007-01-01

326

Astrophysical reaction rates for {sup 58,60}Ni(n,{gamma}) from new neutron capture cross section measurements  

SciTech Connect

New neutron capture cross sections of {sup 58,60}Ni were measured in the energy range from 100 eV to 600 keV using the Oak Ridge Electron Linear Accelerator. The combination of these new neutron capture data with previous transmission data allowed a resonance analysis up to 900 keV using R-matrix theory. The theoretically determined direct capture cross sections were included in the analyses. From these resonance parameters and the direct capture contribution, new (n,{gamma}) astrophysical reaction rates were determined over the entire energy range needed by the latest stellar models describing the so-called weak s process.

Guber, K. H.; Derrien, H.; Leal, L. C.; Arbanas, G.; Wiarda, D. [Nuclear Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Koehler, P. E.; Harvey, J. A. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

2010-11-15

327

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

E-print Network

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...

Bosko, Andrey

2005-11-01

328

Clinical review of the Japanese experience with boron neutron capture therapy and a proposed strategy using epithermal neutron beams.  

PubMed

Our concept of boron neutron capture therapy (BNCT) is selective destruction of tumor cells using the heavy-charged particles yielded through 10B(n, alpha)7 Li reactions. To design a new protocol that employs epithermal neutron beams in the treatment of glioma patients, we examined the relationship between the radiation dose, histological tumor grade, and clinical outcome. Since 1968, 183 patients with different kinds of brain tumors were treated by BNCT; for this retrospective study, we selected 105 patients with glial tumors who were treated in Japan between 1978 and 1997. In the analysis of side effects due to radiation, we included all the 159 patients treated between 1977 and 2001. With respect to the radiation dose (i.e. physical dose of boron n-alpha reaction), the new protocol prescribes a minimum tumor volume dose of 15 Gy or, alternatively, a minimum target volume dose of 18 Gy. The maximum vascular dose should not exceed 15 Gy (physical dose of boron n-alpha reaction) and the total amount of gamma rays should remain below 10 Gy, including core gamma rays from the reactor and capture gamma in brain tissue. The outcomes for 10 patients who were treated by the new protocol using a new mode composed of thermal and epithermal neutrons are reported. PMID:12749705

Nakagawa, Yoshinobu; Pooh, Kyonghon; Kobayashi, Toru; Kageji, Teruyoshi; Uyama, Shinichi; Matsumura, Akira; Kumada, Hiroaki

2003-01-01

329

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

PubMed

A modeling investigation was performed to choose moderator material and size for creating optimal epithermal neutron beams for BNCT based on a proton accelerator and the (7)Li(p,n)(7)Be reaction as a neutrons source. An optimal configuration is suggested for the beam shaping assembly made from polytetrafluoroethylene and magnesium fluorine to be placed on high current IPPE proton accelerator KG-2.5. Results of calculation were experimentally tested and are in good agreement with measurements. PMID:15308184

Kononov, O E; Kononov, V N; Bokhovko, M V; Korobeynikov, V V; Soloviev, A N; Sysoev, A S; Gulidov, I A; Chu, W T; Nigg, D W

2004-11-01

330

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

331

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

PubMed Central

Background Boron neutron capture reaction (BNCR) is based on irradiation of tumors after accumulation of boron compound. 10B captures neutrons and produces an alpha (4He) particle and a recoiled lithium nucleus (7Li). These particles have the characteristics of high linear energy transfer (LET) radiation and have marked biological effects. The purpose of this study is to verify that BNCR will increase cell killing and slow disappearance of repair protein-related foci to a greater extent in DNA repair-deficient cells than in wild-type cells. Methods Chinese hamster ovary (CHO-K1) cells and a DNA double-strand break (DSB) repair deficient mutant derivative, xrs-5 (Ku80 deficient CHO mutant cells), were irradiated by thermal neutrons. The quantity of DNA-DSBs following BNCR was evaluated by measuring the phosphorylation of histone protein H2AX (gamma-H2AX) and 53BP1 foci using immunofluorescence intensity. Results Two hours after neutron irradiation, the number of gamma-H2AX and 53BP1 foci in the CHO-K1 cells was decreased to 36.5-42.8% of the levels seen 30 min after irradiation. In contrast, two hours after irradiation, foci levels in the xrs-5 cells were 58.4-69.5% of those observed 30 min after irradiation. The number of gamma-H2AX foci in xrs-5 cells at 60-120 min after BNCT correlated with the cell killing effect of BNCR. However, in CHO-K1 cells, the RBE (relative biological effectiveness) estimated by the number of foci following BNCR was increased depending on the repair time and was not always correlated with the RBE of cytotoxicity. Conclusion Mutant xrs-5 cells show extreme sensitivity to ionizing radiation, because xrs-5 cells lack functional Ku-protein. Our results suggest that the DNA-DSBs induced by BNCR were not well repaired in the Ku80 deficient cells. The RBE following BNCR of radio-sensitive mutant cells was not increased but was lower than that of radio-resistant cells. These results suggest that gamma-ray resistant cells have an advantage over gamma-ray sensitive cells in BNCR. PMID:21888676

2011-01-01

332

Development of the JAERI computational dosimetry system (JCDS) for boron neutron capture therapy. Cooperative research  

E-print Network

The Neutron Beam Facility at JRR-4 enables us to carry out boron neutron capture therapy with epithermal neutron beam. In order to make treatment plans for performing the epithermal neutron beam BNCT, it is necessary to estimate radiation doses in a patient's head in advance. The JAERI Computational Dosimetry System (JCDS), which can estimate distributions of radiation doses in a patient's head by simulating in order to support the treatment planning for epithermal neutron beam BNCT, was developed. JCDS is a software that creates a 3-dimentional head model of a patient by using CT and MRI images, and that generates a input data file automatically for calculation of neutron flux and gamma-ray dose distributions in the brain with the Monte Carlo code MCNP, and that displays these dose distributions on the head model for dosimetry by using the MCNP calculation results. JCDS has any advantages as follows; By using CT data and MRI data which are medical images, a detail three-dimensional model of patient's head is...

Kumada, H; Matsumura, A; Nakagawa, Y; Nose, T; Torii, Y; Uchiyama, J; Yamamoto, K; Yamamoto, T

2003-01-01

333

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

334

Using (d,p?) as a Surrogate for Neutron Capture with ^75As  

NASA Astrophysics Data System (ADS)

Arsenic is used as a radiochemical neutron fluence detector for nuclear reactions and other applications. The abundances of the residual isotopes ^73,74As allow one to calculate the total neutron activity through (n,2n) or (n,?) reactions along the isotopic network chain. The neutron capture reaction cross sections used for these calculations cannot be directly measured for the radioactive isotopes, but the (d,p?) reaction as a surrogate for the (n,?) reaction can be measured. An experiment at Oak Ridge National Laboratory using As beams in inverse kinematics and a deuterated target will first measure the ^75As(d,p?) reaction with stable beam to test the efficacy of our surrogate experimental techniques. With a tight geometry, eight ORRUBA silicon-strip detectors will detect recoil protons in coincidence with ?-rays detected by four high-purity segmented Ge clover detectors. Status and future goals for the As(d,p?) surrogate campaign will be presented.

Peters, W. A.; Cizewski, J. A.; Hatarik, R.; O'Malley, P.; Vieira, D. J.; Jandel, M.; Wilhelmy, J. B.; Matei, C.; Bardayan, D. W.; Smith, M. S.; Pain, S. D.; Jones, K. L.; Moazen, B. H.; Chae, K. Y.; Kozub, R. L.; Shriner, J.; Blackmon, J. C.

2008-10-01

335

Sensitivity studies of beam directionality, beam size, and neutron spectrum for a fission converter-based epithermal neutron beam for boron neutron capture therapy.  

PubMed

Sensitivity studies of epithermal neutron beam performance in boron neutron capture therapy are presented for realistic neutron beams with varying filter/moderator and collimator/delimiter designs to examine the relative importance of neutron beam spectrum, directionality, and size. Figures of merit for in-air and in-phantom beam performance are calculated via the Monte Carlo technique for different well-optimized designs of a fission converter-based epithermal neutron beam with head phantoms as the irradiation target. It is shown that increasing J/phi, a measure of beam directionality, does not always lead to corresponding monotonic improvements in beam performance. Due to the relatively low significance, for most configurations, of its effect on in-phantom performance and the large intensity losses required to produce beams with very high J/phi, beam directionality should not be considered an important figure of merit in epithermal neutron beam design except in terms of its consequences on patient positioning and collateral dose. Hardening the epithermal beam spectrum, while maintaining the specific fast neutron dose well below the inherent hydrogen capture dose, improves beam penetration and advantage depth and, as a desirable by-product, significantly increases beam intensity. Beam figures of merit are shown to be strongly dependent on beam size relative to target size. Beam designs with J/phi approximately 0.65-0.7, specific fast neutron doses of 2-2.6x10(-13) Gy cm2/n and beam sizes equal to or larger than the size of the head target produced the deepest useful penetration, highest therapeutic ratios, and highest intensities. PMID:10505888

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

1999-09-01

336

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

E-print Network

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

Harris, Thomas C. (Thomas Cameron)

2006-01-01

337

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

NASA Astrophysics Data System (ADS)

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

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

338

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

339

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

NASA Astrophysics Data System (ADS)

The neutron capture cross section and capture ?-ray spectra of 142Nd in the neutron energy ranges from 15 to 95 keV, and around 550 keV have been measured by the time-of-flight method. Capture ?-rays were detected with an anti-Compton NaI(Tl) spectrometer, and the pulse-height weighting technique was applied to derive the neutron capture cross section. The capture ?-ray spectra were obtained by unfolding the detector pulse-height spectra with the detector response matrix. The results were compared with previous measurements and cross section data in the evaluated nuclear data libraries, JENDL-4.0 and ENDF/B-VII.0.

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

2013-03-01

340

A New Thermal Neutron Flux Convention  

Microsoft Academic Search

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

T B Ryves

1969-01-01

341

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

NASA Astrophysics Data System (ADS)

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 15N7++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)].

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

1999-11-01

342

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

343

Measurements at n_TOF of the Neutron Capture Cross Section of Minor Actinides Relevant to the Nuclear Waste Transmutation  

Microsoft Academic Search

Accurate and reliable neutron-capture cross-section data for actinides are necessary for the proper design, safety regulation, and precise performance assessment of transmutation devices such as Fast Critical Reactors or Accelerator Driven Systems. In particular, the neutron-capture cross sections of 237Np, 240Pu, and 243Am play a key role in the design and optimization of a strategy for the Nuclear Waste Transmutation.

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

2005-01-01

344

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.; Bécares, V.; Be?vá?, F.; Belloni, F.; Billowes, J.; Brugger, M.; Calviani, M.; Calviño, F.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Dillmann, I.; Domingo-Pardo, C.; Duran, I.; Eleftheriadis, C.; Fernández-Ordóñez, M.; Ferrari, A.; Ganesan, S.; Giubrone, G.; Gómez-Hornillos, M. B.; Gonçalves, I. F.; González-Romero, E.; Gramegna, F.; Griesmayer, E.; Gunsing, F.; Jenkins, D.; Jericha, E.; Kadi, Y.; Käppeler, 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.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vermeullen, M.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weiß, C.; Wright, T.

2012-03-01

345

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

PubMed

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

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

2011-12-01

346

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 PMID:9043021

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

1997-01-01

347

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

SciTech Connect

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.

Moss, R.L. (Institute of Advanced Materials, Petten Establishment (Netherlands))

1990-01-01

348

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

349

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

PubMed

The temperature in the crust of an accreting neutron star, which comprises its outermost kilometre, is set by heating from nuclear reactions at large densities, neutrino cooling and heat transport from the interior. The heated crust has been thought to affect observable phenomena at shallower depths, such as thermonuclear bursts in the accreted envelope. Here we report that cycles of electron capture and its inverse, ?(-) decay, involving neutron-rich nuclei at a typical depth of about 150?metres, cool the outer neutron star crust by emitting neutrinos while also thermally decoupling the surface layers from the deeper crust. This 'Urca' mechanism has been studied in the context of white dwarfs and type Ia supernovae, but hitherto was not considered in neutron stars, because previous models computed the crust reactions using a zero-temperature approximation and assumed that only a single nuclear species was present at any given depth. The thermal decoupling means that X-ray bursts and other surface phenomena are largely independent of the strength of deep crustal heating. The unexpectedly short recurrence times, of the order of years, observed for very energetic thermonuclear superbursts are therefore not an indicator of a hot crust, but may point instead to an unknown local heating mechanism near the neutron star surface. PMID:24291788

Schatz, H; Gupta, S; Möller, P; Beard, M; Brown, E F; Deibel, A T; Gasques, L R; Hix, W R; Keek, L; Lau, R; Steiner, A W; Wiescher, M

2014-01-01

350

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

E-print Network

Europium resonance parameters from neutron capture and transmission measurements in the energy Transmission Capture Thermal cross section RPI Resonance parameters a b s t r a c t Europium is a good absorber-segment sodium iodide multiplicity detector. Resonance parameters were extracted from the data using

Danon, Yaron

351

Comparative assessment of single-dose and fractionated boron neutron capture therapy  

SciTech Connect

The effects of fractionating boron neutron capture therapy (BNCT) were evaluated in the intracerebral rat 9L gliosarcoma and rat spinal cord models using the Brookhaven Medical Research Reactor (BMRR) thermal neutron beam. The amino acid analog p-boronophenylalanine (BPA) was administered prior to each exposure to the thermal neutron beam. The total physical absorbed dose to the tumor during BNCT using BPA was 91% high-linear energy transfer (LET) radiation. Two tumor doses of 5.2 Gy spaced 48 h apart (n = 14) or three tumor doses of 5.2 Gy, each separated by 48 h (n = 10), produced 50 and 60% long-term (>1 year) survivors, respectively. The outcome of neither the two nor the three fractions of radiation was statistically different from that of the corresponding single-fraction group. In the rat spinal cord, the ED{sub 50} for radiation myelopathy (as indicated by limb paralysis within 7 months) after exposure to the thermal beam alone was 13.6 {+-} 0.4 Gy. Dividing the beam-only irradiation into two or four consecutive daily fractions increased the ED{sub 50} to 14.7 {+-} 0.2 Gy and 15.5 {+-} 0.4 Gy, respectively. Thermal neutron irradiation in the presence of BPA resulted in an ED{sub 50} for myelopathy of 13.8 {+-} 0.6 Gy after a single fraction and 14.9 {+-} 0.9 Gy after two fractions. An increase in the number of fractions to four resulted in an ED{sub 50} of 14.3 {+-} 0.6 Gy. The total physical absorbed dose to the blood in the vasculature of the spinal cord during BNCT using BPA was 80% high-LET radiation. It was observed that fractionation was of minor significance in the amelioration of damage to the normal central nervous system in the rat after boron neutron capture irradiation. 30 refs., 5 figs., 3 tabs.

Coderre, J.A.; Micca, P.L.; Fisher, C.D. [Brookhaven National Laboratory, Upton, NY (United States)] [and others

1995-12-01

352

Precision Measurement of Parity Violation in Polarized Cold Neutron Capture on the Proton the NPD $\\gamma$ Experiment  

E-print Network

The NPDGamma experiment at the Los Alamos Neutron Science Center (LANSCE) is dedicated to measure with high precision the parity violating asymmetry in the $\\gamma$ emission after capture of spin polarized cold neutrons in para-hydrogen. The measurement will determine unambiguously the weak pion-nucleon-nucleon ($\\pi NN$) coupling constant {\\it f$^1_{\\pi}$}

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

2006-01-01

353

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

SciTech Connect

Purpose: To analyze the possible increase in efficacy of boron neutron capture therapy (BNCT) for undifferentiated thyroid carcinoma (UTC) by using p-boronophenylalanine (BPA) plus 2,4-bis ({alpha},{beta}-dihydroxyethyl)-deutero-porphyrin IX (BOPP) and BPA plus nicotinamide (NA) as a radiosensitizer of the BNCT reaction. Methods and Materials: Nude mice were transplanted with a human UTC cell line (ARO), and after 15 days they were treated as follows: (1) control, (2) NCT (neutrons alone), (3) NCT plus NA (100 mg/kg body weight [bw]/day for 3 days), (4) BPA (350 mg/kg bw) + neutrons, (5) BPA + NA + neutrons, and (6) BPA + BOPP (60 mg/kg bw) + neutrons. The flux of the mixed (thermal + epithermal) neutron beam was 2.8 x 10{sup 8} n/cm{sup 2}/sec for 83.4 min. Results: Neutrons alone or with NA caused some tumor growth delay, whereas in the BPA, BPA + NA, and BPA + BOPP groups a 100% halt of tumor growth was observed in all mice at 26 days after irradiation. When the initial tumor volume was 50 mm{sup 3} or less, complete remission was found with BPA + NA (2 of 2 mice), BPA (1 of 4), and BPA + BOPP (7 of 7). After 90 days of complete regression, recurrence of the tumor was observed in BPA + NA (2 of 2) and BPA + BOPP (1 of 7). The determination of apoptosis in tumor samples by measurements of caspase-3 activity showed an increase in the BNCT (BPA + NA) group at 24 h (p < 0.05 vs. controls) and after the first week after irradiation in the three BNCT groups. Terminal transferase dUTP nick end labeling analysis confirmed these results. Conclusions: Although NA combined with BPA showed an increase of apoptosis at early times, only the group irradiated after the combined administration of BPA and BOPP showed a significantly improved therapeutic response.

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

2007-11-15

354

Neutron Capture Rates near A=130 which Effect a Global Change to the r-Process Abundance Distribution  

SciTech Connect

We investigate the impact of neutron capture rates near the A=130 peak on the r-process abundance pattern. We show that these capture rates can alter the abundances of individual nuclear species, not only in the region of A=130 peak but also throughout the abundance pattern. We discuss in general the nonequilibrium processes that produce these abundance changes and determine which capture rates have the most significant impact.

Surman, Rebecca [Union College; Beun, Joshua [North Carolina State University; Mclaughlin, Gail C [North Carolina State University; Hix, William Raphael [ORNL

2009-01-01

355

Neutron capture rates near A=130 that effect a global change to the r-process abundance distribution  

SciTech Connect

We investigate the impact of neutron capture rates near the A=130 peak on the r-process abundance pattern. We show that these capture rates can alter the abundances of individual nuclear species, not only in the region of A=130 peak but also throughout the abundance pattern. We discuss in general the nonequilibrium processes that produce these abundance changes and determine which capture rates have the most significant impact.

Surman, R.; Beun, J.; McLaughlin, G. C.; Hix, W. R. [Department of Physics, Union College, Schenectady, New York 12308 (United States); Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States); Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6374 (United States)

2009-04-15

356

The requirements and development of neutron beams for neutron capture therapy of brain cancer  

Microsoft Academic Search

One of the two overriding conditions for successfulBNCT is that there must be a sufficientnumber of thermal neutrons delivered to each ofthe boronated cells in the tumour bed (targetvolume). Despite the poor experience with BNCT inthe USA some 40 years ago, the continuedapparent success of BNCT in Japan since 1968,lead indirectly to the re-start of clinical trialson BNCT in 1994

R. L. Moss; O. Aizawa; D. Beynon; R. Brugger; G. Constantine; O. Harling; H. B. Liu; P. Watkins

1997-01-01

357

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

PubMed

GEANT4 is a Monte Carlo code originally implemented for high-energy physics applications and is well known for particle transport at high energies. The capacity of GEANT4 to simulate neutron transport in the thermal energy region is not equally well known. The aim of this article is to compare MCNP, a code commonly used in low energy neutron transport calculations and GEANT4 with experimental results and select the suitable code for gadolinium neutron capture applications. To account for the thermal neutron scattering from chemically bound atoms [S(alpha,beta)] in biological materials a comparison of thermal neutron fluence in tissue-like poly(methylmethacrylate) phantom is made with MCNP4B, GEANT4 6.0 patch1, and measurements from the neutron capture therapy (NCT) facility at the Studsvik, Sweden. The fluence measurements agreed with MCNP calculated results considering S(alpha,beta). The location of the thermal neutron peak calculated with MCNP without S(alpha,beta) and GEANT4 is shifted by about 0.5 cm towards a shallower depth and is 25%-30% lower in amplitude. Dose distribution from the gadolinium neutron capture reaction is then simulated by MCNP and compared with measured data. The simulations made by MCNP agree well with experimental results. As long as thermal neutron scattering from chemically bound atoms are not included in GEANT4 it is not suitable for NCT applications. PMID:16532938

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

2006-02-01

358

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

SciTech Connect

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

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

2006-02-15

359

Neutron Capture in the r-Process -- Do We Know Them And Does It Make Any Difference?  

E-print Network

The r-process involves neutron-rich nuclei far off stability for which no experimental cross sections are known. Therefore, one has to rely on theory which might be prone to considerable uncertainties far off stability. To investigate the impact of such uncertainties, nucleosynthesis in hot bubble models followed completely from high-temperature NSE to low-temperature neutron capture freeze-out were calculated with largely varied rates. Due to the (n,gamma)-(gamma,n) equilibrium established at the onset of the r-process, only late-time neutron captures are important which mainly modify the abundances around the third r-process peak.

T. Rauscher

2004-07-16

360

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

361

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

362

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

363

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

PubMed Central

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

Hainfeld, J F

1992-01-01

364

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

SciTech Connect

Boron neutron capture therapy offers the potentiality for treating brain tumors currently resistant to treatment. The success of this form of therapy is directly dependent upon the delivery of sufficient numbers of thermal-neutrons to tumor cells which possess high concentrations of B-10. The objective of this project is to develop chemical methodology to synthesize boron-containing compounds with the potential for becoming incorporated into rapidly-dividing malignant brain tumor cells and excluded from normal components of the brain and surrounding tissues, to develope biological methods for assessing the potential of the compound by use of cell culture or intratumoral injection, to develop analytical methodology for measuring boron in cells and tissue using direct current plasma atomic emission spectroscopy (DCP-AES) and alpha track autoradiography, to develop biochemical and HPLC procedures for evaluating compound uptake and tissue half-life, and to develop procedures required to assess both in vitro and vivo efficacy of BNCT with selected compounds.

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

1990-01-01

365

Preparation of thin arsenic and radioarsenic targets for neutron capture studies  

SciTech Connect

A simple method for the electrodeposition of elemental arsenic (As) on a metal backing from aqueous solutions has been developed. The method was successfully applied to stable As (As-75). Thin (2.5 mg {center_dot} cm{sup -2}) coherent, smooth layers of the metalloid on Ti foils (2.5 {micro}m thickness) were obtained. Electrodeposits served as targets for {sup 75}As(n,{gamma}) {sup 76}As neutron capture experiments at Los Alamos Neutron Science Center (LANSCE). Respective {sup 73}As(n,{gamma}) {sup 74}As experiments are planned for the near future, and {sup 73}As targets will be prepared in a similar fashion utilizing the introduced electrodeposition method. The preparation of an {sup 73}As (half-life 80.3 d) plating bath solution from proton irradiated germanium has been demonstrated. Germanium target irradiation was performed at the Los Alamos Isotope Production Facility (IPF).

Fassbender, Michael E [Los Alamos National Laboratory

2009-01-01

366

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

NASA Astrophysics Data System (ADS)

As Boron Neutron Capture Therapy (BNCT) clinical trials are initiated in more countries, new treatment planning software programs are being developed to calculate dose distributions in patient specific models. A reference suite of test problems, i.e., head phantom irradiations and resulting depth-dose curves, would allow quantitative comparison of the treatment planning software. This paper presents sets of central axis depth vs. dose curves calculated with the Monte Carlo radiation transport code MCNP4B for five different representations of the Snyder head phantom. The first is a multi-shell analytic ellipsoidal representation, and the remaining four are voxelized representations with cube edge lengths of 16, 10, 8 and 4 mm. For these calculations, 10 cm diameter monoenergetic and monodirectional neutron and photon beams were incident along the central axes of the models. Individual beams of 0.0253 eV, 1, 2, 10, 100 and 1000 keV neutrons, and 0.2, 0.5, 1, 2, 5, and 10 MeV photons were simulated to high statistical convergence, with statistical error less than 1% in the center of the model. A "generic" epithermal neutron beam, with 1% fast flux contamination and 10% thermal flux contamination, similar to those proposed for BNCT treatments, was also simulated with all five models. Computations for both of the smaller sized voxel models produced thermal neutron, fast neutron, and gamma dose rates within 4% of those from the analytical representation. It is proposed that these data sets be used by the BNCT community for the verification of existing and new BNCT treatment planning software.

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

367

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

368

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

369

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

370

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

NASA Astrophysics Data System (ADS)

Purpose of paper is to confirm the feasibility of acquisition of three dimensional single photon emission computed tomography image from boron neutron capture therapy using Monte Carlo simulation. Prompt gamma ray (478 keV) was used to reconstruct image with ordered subsets expectation maximization method. From analysis of receiver operating characteristic curve, area under curve values of three boron regions were 0.738, 0.623, and 0.817. The differences between length of centers of two boron regions and distance of maximum count points were 0.3 cm, 1.6 cm, and 1.4 cm.

Yoon, Do-Kun; Jung, Joo-Young; Jo Hong, Key; Suk Suh, Tae

2014-02-01

371

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

NASA Astrophysics Data System (ADS)

We provide a model-independent calculation of the radiative neutron capture on lithium-7 over an energy range where the contribution from the 3+ resonance becomes important by using halo effective field theory. We describe how the couplings in the EFT Lagrangian are constrained from available data on low-lying bound and resonance states. We also present power counting arguments that establish a hierarchy for electromagnetic one- and two-body currents. Our model independent results quantify the current uncertainties in nuclear theory in the single particle approximation.

Fernando, Lakma; Higa, Renato; Rupak, Gautam

2012-10-01

372

Epithermal neutron beams for clinical studies of boron neutron capture therapy: a dosimetric comparison of seven beams.  

PubMed

A comparison of seven epithermal neutron beams used in clinical studies of boron neutron capture therapy (BNCT) in Sweden (Studsvik), Finland (Espoo), Czech Republic (ReZ), The Netherlands (Petten) and the U.S. (Brookhaven and Cambridge) was performed to facilitate sharing of preclinical and clinical results. The physical performance of each beam was measured using a common dosimetry method under conditions pertinent to brain irradiations. Neutron fluence and absorbed dose measurements were performed with activation foils and paired ionization chambers on the central axis both in air and in an ellipsoidal water phantom. The overall quality of each beam was assessed by figures of merit determined from the total weighted dose profiles that assumed the presence of boron in tissue. The in-air specific beam contamination from both fast neutrons and gamma rays ranged between 8 and 65 x 10(-11) cGy(w) cm2 for the different beams and the epithermal neutron flux intensities available at the patient position differed by more than a factor of 20 from 0.2-4.3 x 10(9) n cm(-2) s(-1). Percentage depth dose profiles measured in-phantom for the individual photon, thermal and fast-neutron dose components differed only subtly in shape between facilities. Assuming uptake characteristics consistent with the currently used boronated phenylalanine, all the epithermal beams exhibit a useful penetration of 8 cm or greater that is sufficient to irradiate a lesion seated at the brain midline. The performance of the existing facilities will benefit from the introduction of advanced compounds through improved beam penetrability. This could increase by as much as 2 cm for the purest of beams, although the beam intensities generally need to be increased to between 2-5 x 10(9) n cm(-2) s(-1) to maintain manageable irradiation times. These data provide the first consistent measurement of beam performance at the different centers and will enable a preliminary normalization of the calculated patient dosimetry. PMID:16038592

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

2005-08-01

373

Study of slow dynamics in supercooled water by molecular dynamics and quasi-elastic neutron scattering  

E-print Network

The slow dynamics of supercooled water is studied by modelling the spectrum of test particle fluctuations: intermediate scattering function (ISF). The theoretical models are compared with experimental measurements by ...

Liu, Li, Ph. D. Massachusetts Institute of Technology

2005-01-01

374

An investigation of boron neutron capture therapy for recurrent glioblastoma multiforme.  

PubMed

Objectives - To explore the use of boron neutron capture therapy (BNCT) for patients with glioblastoma multiforme (GBM), recurring after surgery and conventional radiotherapy (photon radiotherapy). Materials and Methods - Boron uptake in recurrent GBM was measured for four patients. Twelve patients were subsequently treated by BNCT with boronophenylalanine-fructose (900 mg/kg body weight), administered by intravenous infusion for 6 h. Results - Median survival time from initial diagnosis was 22.2 months. Comparison with other BNCT studies indicates a clinical advantage of the prolonged infusion. BNCT was well tolerated and quality of life remained stable until tumor progression for all 12 patients. No correlation was found between survival times and minimum tumor dose and number of radiation fields. Conclusions - Boron neutron capture therapy, with the prolonged procedure for infusion, is at least as effective as other radiation therapies for recurrent GBM and is delivered in one treatment session, with low radiation dose to the healthy brain. Survival from diagnosis compares favorably with that obtained with conventional radiotherapy plus concomitant and adjuvant temozolomide (TMZ) and survival from recurrence compares favorably with that obtained with TMZ at first relapse. The results of the present investigation are encouraging and should be confirmed in a randomized trial. PMID:18297764

Pellettieri, L; H-Stenstam, B; Rezaei, A; Giusti, V; Sköld, K

2008-03-01

375

Hemorrhage in mouse tumors induced by dodecaborate cluster lipids intended for boron neutron capture therapy.  

PubMed

The potential of boron-containing lipids with three different structures, which were intended for use in boron neutron capture therapy, was investigated. All three types of boron lipids contained the anionic dodecaborate cluster as the headgroup. Their effects on two different tumor models in mice following intravenous injection were tested; for this, liposomes with boron lipid, distearoyl phosphatidylcholine, and cholesterol as helper lipids, and containing a polyethylene glycol lipid for steric protection, were administered intravenously into tumor-bearing mice (C3H mice for SCCVII squamous cell carcinoma and BALB/c mice for CT26/WT colon carcinoma). With the exception of one lipid (B-THF-14), the lipids were well tolerated, and no other animal was lost due to systemic toxicity. The lipid which led to death was not found to be much more toxic in cell culture than the other boron lipids. All of the lipids that were well tolerated showed hemorrhage in both tumor models within a few hours after administration. The hemorrhage could be seen by in vivo magnetic resonance and histology, and was found to occur within a few hours. The degree of hemorrhage depended on the amount of boron administered and on the tumor model. The observed unwanted effect of the lipids precludes their use in boron neutron capture therapy. PMID:25114527

Schaffran, Tanja; Jiang, Nan; Bergmann, Markus; Küstermann, Ekkehard; Süss, Regine; Schubert, Rolf; Wagner, Franz M; Awad, Doaa; Gabel, Detlef

2014-01-01

376

Inertial electrostatic confinement: A unique compact accelerator-target source for neutron capture therapy  

SciTech Connect

The economic development of neutron capture therapy requires the availability of a compact, relatively inexpensive neutron source. A variety of accelerator-target concepts are considered competitors for this application, but all require considerable research and development to achieve the goals desired. In this presentation, a new concept is described, the Inertial Electrostatic Confinement or IEC device. The IEC is, in effect, an integrated ion-accelerator, plasma-target device. The use of a plasma-target removes the traditional target-heating issues, transferring heating to other components where it is more easily handled. A gaseous discharge in deuterium (or deuterium-tritium [D-T] mixtures) is developed between a spherical grid and the spherical vacuum-vessel wall. A high voltage applied to the grid not only creates the discharge, but also simultaneously extracts and focuses the ions into a small high-density volume at the center of the sphere where fusion occurs, producing neutrons. A high efficiency is obtained, since this creates a potential configuration which recirculates scattered ions through the dense center volume. Present experimental devices (30- to 60-cm diameter) at the U. of Illinois routinely produce 10{sup 6-7} 2.54-MeV D-D neutrons/sec steady-state/10{sup 8-9}u 14-MeV D-T n/s equivalent. Even higher neutron-emission rates have been achieved in a new pulsed version. As is, these devices are of interest for laboratory experiments, and a scaled-up version could be considered for human treatment. Concepts and issues related to scale-up will be presented.

Miley, G.H. [Fusion Studies Lab., Urgana, IL (United States)

1994-12-31

377

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

NASA Astrophysics Data System (ADS)

A patient collimator for the fission converter based epithermal neutron beam (FCB) at the Massachusetts Institute of Technology Research Reactor (MITR-II) was built for clinical trials of boron neutron capture therapy (BNCT). A design was optimized by Monte Carlo simulations of the entire beam line and incorporates a modular construction for easy modifications in the future. The device was formed in-house by casting a mixture of lead spheres (7.6 mm diameter) in epoxy resin loaded with either 140 mg cm-3 of boron carbide or 210 mg cm-3 of lithium fluoride (95% enriched in 6Li). The cone shaped collimator allows easy field placement anywhere on the patient and is equipped with a laser indicator of central axis, beam's eye view optics and circular apertures of 80, 100, 120 and 160 mm diameter. Beam profiles and the collateral dose in a half-body phantom were measured for the 160 mm field using fission counters, activation foils as well as tissue equivalent (A-150) and graphite walled ionization chambers. Leakage radiation through the collimator contributes less than 10% to the total collateral dose up to 0.15 m beyond the edge of the aperture and becomes relatively more prominent with lateral displacement. The measured whole body dose equivalent of 24 ± 2 mSv per Gy of therapeutic dose is comparable to doses received during conventional therapy and is due principally (60-80%) to thermal neutron capture reactions with boron. These findings, together with the dose distributions for the primary beam, demonstrate the suitability of this patient collimator for BNCT.

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

2004-05-01

378

Noble gas excimer scintillation following neutron capture in boron thin films  

E-print Network

Far-ultraviolet (FUV) scintillation signals have been measured in heavy noble gases (argon, krypton, xenon) following boron-neutron capture ($^{10}$B($n,\\alpha$)$^7$Li) in $^{10}$B thin films. The observed scintillation yields are comparable to the yields from some liquid and solid neutron scintillators. At noble gas pressures of 10$^7$ kPa, the number of photons produced per neutron absorbed following irradiation of a 1200 nm thick $^{10}$B film was 14,000 for xenon, 11,000 for krypton, and 6000 for argon. The absolute scintillation yields from the experimental configuration were calculated using data from (1) experimental irradiations, (2) thin-film characterizations, (3) photomultiplier tube calibrations, and (4) photon collection modeling. Both the boron films and the photomultiplier tube were characterized at the National Institute of Standards and Technology. Monte Carlo modeling of the reaction cell provided estimates of the photon collection efficiency and the transport behavior of $^{10}$B($n,\\alpha$...

McComb, Jacob C; al-Sheikhly, Mohamed; Thompson, Alan K; Vest, Robert E; Clark, Charles W

2014-01-01

379

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. PMID:24295213

2013-01-01

380

Study of Low Frequency Molecular Motions in Explosives by Slow Neutron Inelastic Scattering.  

National Technical Information Service (NTIS)

The inelastic scattering of neutrons provides a means of studying explosives by which the nature of molecular motions can be determined and through which molecular dynamics can be correlated with macroscopic properties such as thermodynamic quantities. A ...

H. J. Prask, H. P. Boutin, S. Trevino

1966-01-01

381

Pulse-width analysis for neutron capture cross-section measurement using an NaI(Tl) detector  

NASA Astrophysics Data System (ADS)

A fast data acquisition method based on pulse-width analysis was developed for measuring neutron capture cross-sections using an NaI(Tl) detector. The new method was tested by detecting ?-rays from standard ?-ray sources and neutron-induced reactions. Non-linear relation between the ?-ray energy and the pulse width of the detector output signal was studied. The neutron beam experiments were performed using a pulsed neutron beam from a spallation neutron source at the Japan Proton Accelerator Research Complex. Detector-deposited energy spectra were reconstructed from the pulse-width spectra using the parameterized relation between the pulse width and the ?-ray energy. Time response properties of the pulse-width analysis method were compared with the traditional pulse-height analysis method. Detailed analysis of the experimental results demonstrated that the present method was more resistive to intense ?-ray bursts from the spallation neutron source.

Katabuchi, Tatsuya; Matsuhashi, Taihei; Terada, Kazushi; Arai, Takuro; Furutaka, Kazuyoshi; Hara, Kaoru Y.; Harada, Hideo; Hirose, Kentaro; Hori, Jun-ichi; Igashira, Masayuki; Kamiyama, Takashi; Kimura, Atsushi; Kino, Koichi; Kitatani, Fumito; Kiyanagi, Yoshiaki; Koizumi, Mitsuo; Mizumoto, Motoharu; Nakamura, Shoji; Oshima, Masumi; Toh, Yosuke

2014-11-01

382

Neutron Capture Measurements on Minor Actinides at the n_TOF Facility at CERN: Past, Present and Future  

SciTech Connect

The successful development of advanced nuclear systems for sustainable energy production and nuclear waste management depends on high quality nuclear data libraries. Recent sensitivity studies and reports have identified the need for substantially improving the accuracy of neutron cross-section data for minor actinides. The n-TOF collaboration has initiated an ambitious experimental program for the measurement of neutron capture cross sections of minor actinides. Two experimental setups have been constructed for this purpose: a Total Absorption Calorimeter (TAC) for measuring neutron capture cross-sections of low-mass and/or radioactive samples and a set of two low neutron sensitivity C{sub 6}D{sub 6} detectors for the less radioactive materials.

Cano-Ott, D. [CIEMAT, Madrid; Koehler, Paul Edward [ORNL; N_TOF collaboration, [CNR-INFM, Trieste, Italy

2011-01-01

383

Parity Violation in Neutron-Proton Capture -- The NPD Gamma Experiment  

SciTech Connect

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 {sup 3}S{sub 1}-{sup 3}P{sub 1}, long range transition (essentially the Danilov parameter {rho}{sub 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 {rvec n} + p {yields} d + {gamma}. The asymmetry has a predicted size of 5 x 10{sup -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 (-1.1 {+-} 2.1 stat. {+-} 0.2 sys.) x 10{sup -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, M. T. [University of Manitoba, Canada; Bowman, James D [ORNL; Greene, G. L. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Penttila, Seppo I [ORNL; Collaboration, NPDGamma [Various Institutes

2009-01-01

384

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?=[-1.2±2.1?(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=[-1.8±1.9?(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 5×10-8 and the aim of the NPDGamma collaboration is to measure it to 1×10-8. 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

385

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

NASA Astrophysics Data System (ADS)

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?=[-1.2±2.1(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=[-1.8±1.9(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 5×10-8 and the aim of the NPDGamma collaboration is to measure it to 1×10-8. The second phase of the measurement will be performed at the Spallation Neutron Source at Oak Ridge National Laboratory.

Gericke, M. T.; Alarcon, R.; Balascuta, S.; Barrón-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.; Penttilä, 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.; Yuan, V.

2011-01-01

386

Parity violation in neutron-proton capture—The 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 5×10-8 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 (-1.1±2.1 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.; Penttilä, 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

387

Noble gas excimer scintillation following neutron capture in boron thin films  

E-print Network

Far-ultraviolet (FUV) scintillation signals have been measured in heavy noble gases (argon, krypton, xenon) following boron-neutron capture ($^{10}$B($n,\\alpha$)$^7$Li) in $^{10}$B thin films. The observed scintillation yields are comparable to the yields from some liquid and solid neutron scintillators. At noble gas pressures of 107 kPa, the number of photons produced per neutron absorbed following irradiation of a 1200 nm thick $^{10}$B film was 14,000 for xenon, 11,000 for krypton, and 6000 for argon. The absolute scintillation yields from the experimental configuration were calculated using data from (1) experimental irradiations, (2) thin-film characterizations, (3) photomultiplier tube calibrations, and (4) photon collection modeling. Both the boron films and the photomultiplier tube were characterized at the National Institute of Standards and Technology. Monte Carlo modeling of the reaction cell provided estimates of the photon collection efficiency and the transport behavior of $^{10}$B($n,\\alpha$)$^7$Li reaction products escaping the thin films. Scintillation yields increased with gas pressure due to increased ionization and excitation densities of the gases from the $^{10}$B($n,\\alpha$)$^7$Li reaction products, increased frequency of three-body, excimer-forming collisions, and reduced photon emission volumes (i.e., larger solid angle) at higher pressures. Yields decreased for thicker $^{10}$B thin films due to higher average energy loss of the $^{10}$B($n,\\alpha$)$^7$Li reaction products escaping the films. The relative standard uncertainties in the measurements were determined to lie between 14 % and 16 %. The observed scintillation signal demonstrates that noble gas excimer scintillation is promising for use in practical neutron detectors.

Jacob C. McComb; Michael A. Coplan; Mohamed al-Sheikhly; Alan K. Thompson; Robert E. Vest; Charles W. Clark

2014-03-19

388

The use of C 6D 6 detectors for neutron induced capture cross-section measurements in the resonance region  

NASA Astrophysics Data System (ADS)

Hydrogen-free deuterated benzene C 6D 6 liquid scintillators are widely used for high resolution neutron capture cross-section measurements at time-of-flight facilities, using the total energy detection principle in combination with the Pulse Height Weighting Technique (PHWT). The quality of the data deduced from such measurements depends on the accuracy of the detector response that is used in the calculation of the weighting function and on the normalization procedure. In addition, for nuclei with small capture to scattering ratios, i.e. light and near neutron magic nuclei, a correction for the sensitivity of the capture detector to the scattered neutrons is required. The MCNP code was used to simulate both the ?-ray and neutron transport in a C 6D 6 detection system including its surroundings. The weighting functions and neutron sensitivity were then deduced from the simulations and validated by experiments. The simulations have also been used to identify the sources of uncertainties in performing capture cross-section measurements with C 6D 6 detectors.

Borella, A.; Aerts, G.; Gunsing, F.; Moxon, M.; Schillebeeckx, P.; Wynants, R.

2007-07-01

389

Comparison of measured parameters from a 24-keV and a broad spectrum epithermal neutron beam for neutron capture therapy: an identification of consequential parameters.  

PubMed

Epithermal neutron beams are under development in a number of locations in the U.S. and abroad. The increased penetration in tissue provided by these neurons should circumvent problems associated with the rapid attenuation of thermal neutron beams encountered in previous clinical trials of neutron capture therapy (NCT). Physical and radiobiological experiments with two "intermediate energy" or "epithermal" beams have been reported. A comparison is made here between the 24-keV iron-filtered beam at Harwell, England, and the broad-spectrum Al2 O3 moderated beam at the Brookhaven Medical Research Reactor (BMRR). In addition, parameters which are relevant for NCT, and which are best suited for evaluation and comparison of beams, are discussed. Particular attention is paid to the mean neutron energy which can be tolerated without significant reduction of therapeutic gain (TG), where TG is the ratio of tumor dose to maximum normal tissue dose. It is suggested that the simplest and most meaningful parameters for comparison of beam intensity and purity are the epithermal neutron fluence rate, and the fast neutron dose per epithermal neutron (4.2 X 10(-11) rad/neutron for the broad-spectrum beam and 29 X 10(-11) rad/neutron for the 24-keV beam). While the Al2O3 beam is close to optimal, the 24-keV beam produces a significant fast neutron dose which results in a lower TG.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2280734

Fairchild, R G; Saraf, S K; Kalef-Ezra, J; Laster, B H

1990-01-01

390

First Measurement of ?_13 from Delayed Neutron Capture on Hydrogen in the Double Chooz Experiment  

E-print Network

The Double Chooz experiment has determined the value of the neutrino oscillation parameter $\\theta_{13}$ from an analysis of inverse beta decay interactions with neutron capture on hydrogen. This analysis uses a three times larger fiducial volume than the standard Double Chooz assessment, which is restricted to a region doped with gadolinium (Gd), yielding an exposure of 113.1 GW-ton-years. The data sample used in this analysis is distinct from that of the Gd analysis, and the systematic uncertainties are also largely independent, with some exceptions, such as the reactor neutrino flux prediction. A combined rate- and energy-dependent fit finds $\\sin^2 2\\theta_{13}=0.097\\pm 0.034(stat.) \\pm 0.034 (syst.)$, excluding the no-oscillation hypothesis at 2.0 \\sigma. This result is consistent with previous measurements of $\\sin^2 2\\theta_{13}$.

Double Chooz Collaboration; Y. Abe; C. Aberle; J. C. dos Anjos; J. C. Barriere; M. Bergevin; A. Bernstein; T. J. C. Bezerra; L. Bezrukhov; E. Blucher; N. S. Bowden; C. Buck; J. Busenitz; A. Cabrera; E. Caden; L. Camilleri; R. Carr; M. Cerrada; P. -J. Chang; P. Chimenti; T. Classen; A. P. Collin; E. Conover; J. M. Conrad; J. I. Crespo-Anadón; K. Crum; A. Cucoanes; E. Damon; J. V. Dawson; S. Dazeley; D. Dietrich; Z. Djurcic; M. Dracos; V. Durand; J. Ebert; Y. Efremenko; M. Elnimr; A. Erickson; A. Etenko; M. Fallot; M. Fechner; F. von Feilitzsch; J. Felde; S. M. Fernandes; V. Fischer; D. Franco; A. J. Franke; M. Franke; H. Furuta; R. Gama; I. Gil-Botella; L. Giot; M. Göger-Neff; L. F. G. Gonzalez; L. Goodenough; M. C. Goodman; J. TM. Goon; D. Greiner; N. Haag; S. Habib; C. Hagner; T. Hara; F. X. Hartmann; J. Haser; A. Hatzikoutelis; T. Hayakawa; M. Hofmann; G. A. Horton-Smith; A. Hourlier; M. Ishitsuka; J. Jochum; C. Jollet; C. L. Jones; F. Kaether; L. N. Kalousis; Y. Kamyshkov; D. M. Kaplan; T. Kawasaki; G. Keefer; E. Kemp; H. de Kerret; T. Konno; D. Kryn; M. Kuze; T. Lachenmaier; C. E. Lane; C. Langbrandtner; T. Lasserre; A. Letourneau; D. Lhuillier; H. P. Lima Jr; M. Lindner; J. M. López-Castaño; J. M. LoSecco; B. K. Lubsandorzhiev; S. Lucht; D. McKee; J. Maeda; C. N. Maesano; C. Mariani; J. Maricic; J. Martino; T. Matsubara; G. Mention; A. Meregaglia; M. Meyer; T. Miletic; R. Milincic; H. Miyata; Th. A. Mueller; Y. Nagasaka; K. Nakajima; P. Novella; M. Obolensky; L. Oberauer; A. Onillon; A. Osborn; I. Ostrovskiy; C. Palomares; I. M. Pepe; S. Perasso; P. Perrin; P. Pfahler; A. Porta; W. Potzel; G. Pronost; J. Reichenbacher; B. Reinhold; A. Remoto; M. Röhling; R. Roncin; S. Roth; B. Rybolt; Y. Sakamoto; R. Santorelli; F. Sato; S. Schönert; S. Schoppmann; T. Schwetz; M. H. Shaevitz; S. Shimojima; D. Shrestha; J-L. Sida; V. Sinev; M. Skorokhvatov; E. Smith; J. Spitz; A. Stahl; I. Stancu; L. F. F. Stokes; M. Strait; A. Stüken; F. Suekane; S. Sukhotin; T. Sumiyoshi; Y. Sun; R. Svoboda; K. Terao; A. Tonazzo; M. Toups; H. H. Trinh Thi; G. Valdiviesso; C. Veyssiere; S. Wagner; H. Watanabe; B. White; C. Wiebusch; L. Winslow; M. Worcester; M. Wurm; F. Yermia; V. Zimmer

2013-01-14

391

Rational design of gold nanoparticles functionalized with carboranes for application in Boron Neutron Capture Therapy.  

PubMed

In this paper we propose a bottom-up approach to obtain new boron carriers built with ortho-carborane functionalized gold nanoparticles (GNPs) for applications in Boron Neutron Capture Therapy. The interaction between carboranes and the gold surface was assured by one or two SH-groups directly linked to the boron atoms of the B10C2 cage. This allowed obtaining stable, nontoxic systems, though optimal biological performance was hampered by low solubility in aqueous media. To improve cell uptake, the hydrophilic character of carborane functionalized GNPs was enhanced by further coverage with an appropriately tailored diblock copolymer (PEO-b-PCL). This polymer also contained pendant carboranes to provide anchoring to the pre-functionalized GNPs. In vitro tests, carried out on osteosarcoma cells, showed that the final vectors possessed excellent biocompatibility joint to the capacity of concentrating boron atoms in the target, which is encouraging evidenced to pursue applications in vivo. PMID:24140178

Ciani, Laura; Bortolussi, Silva; Postuma, Ian; Cansolino, Laura; Ferrari, Cinzia; Panza, Luigi; Altieri, Saverio; Ristori, Sandra

2013-12-31

392

Microdosimetric study for interpretation of outcomes from boron neutron capture therapy clinical trials.  

PubMed

Boron neutron capture therapy is a brachyradiotherapy utilizing the (10)B(n,alpha)(7)Li reaction that has been used to treat glioblastoma multiforme (GBM), melanoma and colon carcinoma liver metastases. GBM clinical trials resulted in modestly improved life expectancies compared with conventional therapies. Early results trials focused on malignant melanoma and colon carcinoma provide dramatically better results. Macrodosimetry cannot explain these apparent differences. The dichotomy can only be understood using microdosimetry techniques. A computer program has been created to provide an improved tissue model. This model permits the dose in each cell's cytoplasm, nucleus, and the interstitium to be calculated for ellipsoidal cells placed in either random or ordered locations. The nuclei can be centered or eccentric. The new model provides insight into the micro level for differences in the trials. The differences arise from the tissue's cellular geometry and the effects of neighboring cells. These results help to explain the observed clinical outcomes. PMID:17576651

Nichols, T L; Miller, L F; Kabalka, G W; Dudney, T M

2007-01-01

393

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

SciTech Connect

During conventional radiotherapy, the dose that can be delivered to the tumor is limited by the tolerance of the surrounding normal tissue within the treatment volume. Boron Neutron Capture Therapy (BNCT) represents a promising modality for selective tumor irradiation. The key to effective BNCT is selective localization of {sup 10}B in the tumor. We have shown that the synthetic amino acid p-boronophenylalanine (BPA) will selectively deliver boron to melanomas and other tumors such as gliosarcomas and mammary carcinomas. Systemically delivered BPA may have general utility as a boron delivery agent for BNCT. In this paper, BNCT with BPA is used in treatment of experimentally induced gliosarcoma in rats and nonpigmented melanoma in rabbits. The tissue distribution of boron is described, as is response to the BNCT. 6 refs., 4 figs., 1 tab.

Coderre, J.A.; Greenberg, D.; Micca, P.L.; Joel, D.D.; Saraf, S. (Brookhaven National Lab., Upton, NY (USA)); Packer, S. (North Shore Univ. Hospital, Manhasset, NY (USA). Div. of Ophthalmology)

1990-01-01

394

First measurement of ?13 from delayed neutron capture on hydrogen in the Double Chooz experiment  

NASA Astrophysics Data System (ADS)

The Double Chooz experiment has determined the value of the neutrino oscillation parameter ?13 from an analysis of inverse beta decay interactions with neutron capture on hydrogen. This analysis uses a three times larger fiducial volume than the standard Double Chooz assessment, which is restricted to a region doped with gadolinium (Gd), yielding an exposure of 113.1 GW-ton-years. The data sample used in this analysis is distinct from that of the Gd analysis, and the systematic uncertainties are also largely independent, with some exceptions, such as the reactor neutrino flux prediction. A combined rate- and energy-dependent fit finds sin2 2?13=0.097±0.034 (stat.)±0.034 (syst.), excluding the no-oscillation hypothesis at 2.0?. This result is consistent with previous measurements of sin2 2?13.

Abe, Y.; Aberle, C.; dos Anjos, J. C.; Barriere, J. C.; Bergevin, M.; Bernstein, A.; Bezerra, T. J. C.; Bezrukhov, L.; Blucher, E.; Bowden, N. S.; Buck, C.; Busenitz, J.; Cabrera, A.; Caden, E.; Camilleri, L.; Carr, R.; Cerrada, M.; Chang, P.-J.; Chimenti, P.; Classen, T.; Collin, A. P.; Conover, E.; Conrad, J. M.; Crespo-Anadón, J. I.; Crum, K.; Cucoanes, A.; Damon, E.; Dawson, J. V.; Dazeley, S.; Dietrich, D.; Djurcic, Z.; Dracos, M.; Durand, V.; Ebert, J.; Efremenko, Y.; Elnimr, M.; Erickson, A.; Etenko, A.; Fallot, M.; Fechner, M.; von Feilitzsch, F.; Felde, J.; Fernandes, S. M.; Fischer, V.; Franco, D.; Franke, A. J.; Franke, M.; Furuta, H.; Gama, R.; Gil-Botella, I.; Giot, L.; Göger-Neff, M.; Gonzalez, L. F. G.; Goodenough, L.; Goodman, M. C.; Goon, J. TM.; Greiner, D.; Haag, N.; Habib, S.; Hagner, C.; Hara, T.; Hartmann, F. X.; Haser, J.; Hatzikoutelis, A.; Hayakawa, T.; Hofmann, M.; Horton-Smith, G. A.; Hourlier, A.; Ishitsuka, M.; Jochum, J.; Jollet, C.; Jones, C. L.; Kaether, F.; Kalousis, L. N.; Kamyshkov, Y.; Kaplan, D. M.; Kawasaki, T.; Keefer, G.; Kemp, E.; de Kerret, H.; Konno, T.; Kryn, D.; Kuze, M.; Lachenmaier, T.; Lane, C. E.; Langbrandtner, C.; Lasserre, T.; Letourneau, A.; Lhuillier, D.; Lima, H. P.; Lindner, M.; López-Castaño, J. M.; LoSecco, J. M.; Lubsandorzhiev, B. K.; Lucht, S.; McKee, D.; Maeda, J.; Maesano, C. N.; Mariani, C.; Maricic, J.; Martino, J.; Matsubara, T.; Mention, G.; Meregaglia, A.; Meyer, M.; Miletic, T.; Milincic, R.; Miyata, H.; Mueller, Th. A.; Nagasaka, Y.; Nakajima, K.; Novella, P.; Obolensky, M.; Oberauer, L.; Onillon, A.; Osborn, A.; Ostrovskiy, I.; Palomares, C.; Pepe, I. M.; Perasso, S.; Perrin, P.; Pfahler, P.; Porta, A.; Potzel, W.; Pronost, G.; Reichenbacher, J.; Reinhold, B.; Remoto, A.; Röhling, M.; Roncin, R.; Roth, S.; Rybolt, B.; Sakamoto, Y.; Santorelli, R.; Sato, F.; Schönert, S.; Schoppmann, S.; Schwetz, T.; Shaevitz, M. H.; Shimojima, S.; Shrestha, D.; Sida, J.-L.; Sinev, V.; Skorokhvatov, M.; Smith, E.; Spitz, J.; Stahl, A.; Stancu, I.; Stokes, L. F. F.; Strait, M.; Stüken, A.; Suekane, F.; Sukhotin, S.; Sumiyoshi, T.; Sun, Y.; Svoboda, R.; Terao, K.; Tonazzo, A.; Toups, M.; Trinh Thi, H. H.; Valdiviesso, G.; Veyssiere, C.; Wagner, S.; Watanabe, H.; White, B.; Wiebusch, C.; Winslow, L.; Worcester, M.; Wurm, M.; Yermia, F.; Zimmer, V.

2013-06-01

395

The Origins of Germanium and the Transition to Neutron-Capture Nucleosynthesis  

NASA Astrophysics Data System (ADS)

We propose to study the element germanium {Ge, Z=32} in cool stars. Ge has a mass that puts it in a transition region from nucleosynthesis occurring in nuclear statistical equilibrium to charged-particle and neutron-capture reactions. Observational constraints on predictions of the nucleosynthesis of Ge are limited, since Ge has only be detected in cool stars with the UV sensitivity of HST. We propose a new ARCHIVE project that will double the number of cool stars with Ge detections. We will use these data to characterize the different Ge production mechanisms over the history of the Galaxy and understand the chemical evolution of this transition element. This will provide a better understanding of the many nucleosynthesis channels that have produced Ge since the earliest epochs of metal production in stars.

Roederer, Ian

2014-10-01

396

Boron neutron capture therapy and radiation synovectomy research at the Massachusetts Institute of Technology Research Reactor  

SciTech Connect

In this paper, current research in boron neutron capture therapy (BNCT) and radiation synovectomy at the Massachusetts Institute of Technology Research Reactor is reviewed. In the last few years, major emphasis has been placed on the development of BNCT primarily for treatment of brain tumors. This has required a concerted effort in epithermal beam design and construction as well as the development of analytical capabilities for {sup 10}B analysis and patient treatment planning. Prompt gamma analysis and high-resolution track-etch autoradiography have been developed to meet the needs, respectively, for accurate bulk analysis and for quantitative imaging of {sup 10}B in tissue at subcellular resolutions. Monte Carlo-based treatment planning codes have been developed to ensure optimized and individualized patient treatments. In addition, the development of radiation synovectomy as an alternative therapy to surgical intervention is joints that are affected by rheumatoid arthritis is described.

Zamenhof, R.G.; Nwanguma, C.I.; Wazer, D.E.; Saris, S.; Madoc-Jones, H. (Tufts-New England Medical Center, Boston, MA (US)); Sledge, C.B.; Shortkroff, S. (Brigham and Women's Hospital, Boston, MA (US))

1992-04-01

397