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Title: New Approach to M1 Cross Section for the D({gamma},n) via the D(7Li,7Be) Reaction

Abstract

The (7Li,7Be) charge-exchange spin-flip reaction was for the first time used to deduce the distribution of the B(M1) reduced matrix elements for the photodisintegration of deuteron from the analogous B(GT) distribution. The obtained distribution is in agreement with recent photodisintegration measurements and effective-field calculations.

Authors:
; ;  [1]; ; ; ;  [2]; ; ; ; ; ;  [3];  [4]; ;  [5];  [6];  [7]
  1. Department of Physics, University of Tokushima, Tokushima 770-8502 (Japan)
  2. Department of Physics, Konan University, Kobe 658-8501 (Japan)
  3. Research Center for Nuclear Physics, Osaka University, Osaka 567-0047 (Japan)
  4. Natural Science, International Christian University, Tokyo 181-0015 (Japan)
  5. Department of Physics, Osaka University, Osaka 560-0043 (Japan)
  6. Department of Physics, International Christian University, Tokyo 181-0015 (Japan)
  7. Kobe Tokiwa College, Kobe 654-0838 (Japan)
Publication Date:
OSTI Identifier:
20719714
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 802; Journal Issue: 1; Conference: ENS'05: International symposium on exotic nuclear systems, Debrecen (Hungary), 20-25 Jun 2005; Other Information: DOI: 10.1063/1.2140650; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BERYLLIUM 7; CHARGE EXCHANGE; DEUTERONS; LITHIUM 7 REACTIONS; MATRIX ELEMENTS; PHOTONUCLEAR REACTIONS; SPIN FLIP

Citation Formats

Nakayama, S., Fushimi, K., Koori, N., Yamagata, T., Akimune, H., Takeuchi, T., Yonehara, K., Arimoto, Y., Daito, H., Fujimura, H., Fujiwara, M., Takahisa, K., Yoshida, H.P., Ejiri, H., Fujita, Y., Kohri, H., Greenfield, M.B., and Tanaka, M. New Approach to M1 Cross Section for the D({gamma},n) via the D(7Li,7Be) Reaction. United States: N. p., 2005. Web. doi:10.1063/1.2140650.
Nakayama, S., Fushimi, K., Koori, N., Yamagata, T., Akimune, H., Takeuchi, T., Yonehara, K., Arimoto, Y., Daito, H., Fujimura, H., Fujiwara, M., Takahisa, K., Yoshida, H.P., Ejiri, H., Fujita, Y., Kohri, H., Greenfield, M.B., & Tanaka, M. New Approach to M1 Cross Section for the D({gamma},n) via the D(7Li,7Be) Reaction. United States. doi:10.1063/1.2140650.
Nakayama, S., Fushimi, K., Koori, N., Yamagata, T., Akimune, H., Takeuchi, T., Yonehara, K., Arimoto, Y., Daito, H., Fujimura, H., Fujiwara, M., Takahisa, K., Yoshida, H.P., Ejiri, H., Fujita, Y., Kohri, H., Greenfield, M.B., and Tanaka, M. Mon . "New Approach to M1 Cross Section for the D({gamma},n) via the D(7Li,7Be) Reaction". United States. doi:10.1063/1.2140650.
@article{osti_20719714,
title = {New Approach to M1 Cross Section for the D({gamma},n) via the D(7Li,7Be) Reaction},
author = {Nakayama, S. and Fushimi, K. and Koori, N. and Yamagata, T. and Akimune, H. and Takeuchi, T. and Yonehara, K. and Arimoto, Y. and Daito, H. and Fujimura, H. and Fujiwara, M. and Takahisa, K. and Yoshida, H.P. and Ejiri, H. and Fujita, Y. and Kohri, H. and Greenfield, M.B. and Tanaka, M.},
abstractNote = {The (7Li,7Be) charge-exchange spin-flip reaction was for the first time used to deduce the distribution of the B(M1) reduced matrix elements for the photodisintegration of deuteron from the analogous B(GT) distribution. The obtained distribution is in agreement with recent photodisintegration measurements and effective-field calculations.},
doi = {10.1063/1.2140650},
journal = {AIP Conference Proceedings},
number = 1,
volume = 802,
place = {United States},
year = {Mon Nov 21 00:00:00 EST 2005},
month = {Mon Nov 21 00:00:00 EST 2005}
}
  • Using the very precise value of the baryonic density of the Universe recently obtained by WMAP, Big Bang Nucleosynthesis calculations predict a primordial 7Li abundance which is a factor 2 - 3 higher than that observed in galactic halo dwarf stars. Up to now, the role of the 7Be(d,p)2{alpha} reaction has been neglected. We have studied this reaction, for the first time at energies appropriate to the Big Bang environment, at the CYCLONE facility at Louvain-la-Neuve using a radioactive 7Be beam. The experimental set-up is briefly described. Results and consequences for primordial nucleosythensis are discussed.
  • degrees from the /sup 7/Li(p,n)/sup 7/Be reaction were made by the time- offlight technique using 4l- and 64-MeV incident protons. The neutron production cross sections for the fast forward peak (corresponding to excitation of the ground and first excited states of /sup 7/Be) was found to be 33 plus or minus 6 mb/sr at a mean energy of 39 MeV and 36 plus or minus 4 mb/sr at 60 MeV. These results are compared with those reported elsewhere, and the suitability of such /sup 7/Li targets as a source of monoenergetic neutrons is discussed.
  • The 10B(n,{alpha})7Li reaction was studied in the energy range between 1.5 MeV and 5.6 MeV at the 7-MV Van de Graaff accelerator of IRMM by using a gridded ionisation chamber, signal digitisation, and an intrinsic 238U neutron monitor. The aim was to obtain accurate data for the IAEA Coordinated Research Project (CRP) on the improvement of standard cross sections for light elements. The effect of particle leaking was discovered and its implications investigated. The determination of the cross section {sigma}({alpha}0+{alpha}1) strongly benefits from it but measurements of angular distributions, individual cross sections {sigma}({alpha}0) and {sigma}({alpha}1), and the branching ratio {alpha}0/{alpha}1more » are negatively affected. The correct number of reaction events was obtained by identification of unknown particle signatures in the energy spectra as 10B(n,{alpha})7Li events in the form of quasi 7Li+{alpha} particles created by particle leaking. The cross-section ratio 10B(n,{alpha})7Li/238U(n,fission) was measured and the excitation function of 10B(n,{alpha})7Li determined by simultaneously detecting the charged particles from the boron disintegration in the forward hemisphere and the 238U fission fragments in the backward hemisphere. The IRMM cross sections are compared to experimental data of other groups and to predictions of the ENDF/B-VI.8, JENDL-3.3, and JEF-2.2 evaluations.« less
  • The 'world average' of the astrophysical cross section factor , S17(0), is driven by the Seattle result due to the very small quoted uncertainty, which we however demonstrate it to be an overestimated accuracy. We propose more realistic error bars for the Seattle results based on the published Seattle data. This leads to a an uncertainty of the measured slope of S17 and thus an uncertainty due to extrapolation that can be reasonably estimated to be {sub -3.0}{sup +0.0} eV-b.
  • The cross section of the p(n,{gamma})d reaction was directly measured for the first time at E{sub n}=550 keV, where the theoretical E1 transition strength is comparable to the M1 strength. It was determined accurately to be 35.2 (24) {mu}b, and it agrees with the theoretical one which includes the meson-exchange currents. In this work, a prompt discrete {gamma}-ray detection method combined with a pulsed neutron beam and a newly developed Monte Carlo code was essential to obtain an accurate cross section. {copyright} {ital 1997} {ital The American Physical Society}