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Title: Cross section measurements of the Big Bang nucleosynthesis reaction D({alpha},{gamma})6Li by Coulomb dissociation of 6Li

Abstract

The possibility that big-bang nucleosynthesis (BBN) may produce nontrivial amounts of 6Li is under study since the recent observations of this element in old halo stars. However, the interpretation of these observations needs a precise knowledge of the reaction rate of D({alpha}, {gamma})6Li which, at present, is extremely uncertain (a factor of 20) at the energies of astrophysical interest (Ecm {<=} 300 keV). This uncertainty originates from difficulties in both theoretical estimates and experimental determinations of the D({alpha}, {gamma})6Li capture reaction cross section. New measurements of the cross section of D({alpha}, {gamma})6Li reaction using Coulomb dissociation of 6Li at 150 A MeV have been performed recently at GSI. The results will be compared to previous measurements and theoretical calculations.

Authors:
 [1];  [2];  [3]; ; ; ; ; ; ; ; ; ;  [4]; ;  [5]; ; ; ;  [6];  [7] more »;  [8] « less
  1. IPN-Orsay, IN2P3-Universite Paris XI, 91406 Orsay (France)
  2. (Germany)
  3. TU Darmstadt, D-64220 Darmstadt (Germany)
  4. GSI, Postfach 110552, D-64220 Darmstadt (Germany)
  5. Santiago de compostella (Spain)
  6. CSNSM, IN2P3-Universite Paris XI, 91405 Orsay (France)
  7. RIKEN, Hirosawa, Wako, Saitama 351-01 (Japan)
  8. Fachbereich Physik, Philipps Universitaet, D-3550 Marburg (Germany) (and others)
Publication Date:
OSTI Identifier:
20798535
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 831; Journal Issue: 1; Conference: International conference on frontiers in nuclear structure, astrophysics, and reactions - FINUSTAR, Isle of Kos (Greece), 12-17 Sep 2005; Other Information: DOI: 10.1063/1.2200893; (c) 2006 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; ALPHA REACTIONS; CAPTURE; CROSS SECTIONS; DEUTERIUM TARGET; DISSOCIATION; KEV RANGE; LITHIUM 6; MEV RANGE; NUCLEAR REACTION KINETICS; NUCLEOSYNTHESIS; SCATTERING

Citation Formats

Hammache, F., GSI, Postfach 110552, D-64220 Darmstadt, Galaviz, D., Suemmerer, K., Typel, S., Attallah, F., Geissel, H., Hellstroem, M., Koczon, P., Schwab, E., Schwarz, K., Senger, P., Uhlig, F., Caamano, M., Cortina, D., Coc, A., Kiener, J., Tatischeff, V., Thibaud, J. P., Iwasa, N., and Kohlmeyer, B. Cross section measurements of the Big Bang nucleosynthesis reaction D({alpha},{gamma})6Li by Coulomb dissociation of 6Li. United States: N. p., 2006. Web. doi:10.1063/1.2200893.
Hammache, F., GSI, Postfach 110552, D-64220 Darmstadt, Galaviz, D., Suemmerer, K., Typel, S., Attallah, F., Geissel, H., Hellstroem, M., Koczon, P., Schwab, E., Schwarz, K., Senger, P., Uhlig, F., Caamano, M., Cortina, D., Coc, A., Kiener, J., Tatischeff, V., Thibaud, J. P., Iwasa, N., & Kohlmeyer, B. Cross section measurements of the Big Bang nucleosynthesis reaction D({alpha},{gamma})6Li by Coulomb dissociation of 6Li. United States. doi:10.1063/1.2200893.
Hammache, F., GSI, Postfach 110552, D-64220 Darmstadt, Galaviz, D., Suemmerer, K., Typel, S., Attallah, F., Geissel, H., Hellstroem, M., Koczon, P., Schwab, E., Schwarz, K., Senger, P., Uhlig, F., Caamano, M., Cortina, D., Coc, A., Kiener, J., Tatischeff, V., Thibaud, J. P., Iwasa, N., and Kohlmeyer, B. Wed . "Cross section measurements of the Big Bang nucleosynthesis reaction D({alpha},{gamma})6Li by Coulomb dissociation of 6Li". United States. doi:10.1063/1.2200893.
@article{osti_20798535,
title = {Cross section measurements of the Big Bang nucleosynthesis reaction D({alpha},{gamma})6Li by Coulomb dissociation of 6Li},
author = {Hammache, F. and GSI, Postfach 110552, D-64220 Darmstadt and Galaviz, D. and Suemmerer, K. and Typel, S. and Attallah, F. and Geissel, H. and Hellstroem, M. and Koczon, P. and Schwab, E. and Schwarz, K. and Senger, P. and Uhlig, F. and Caamano, M. and Cortina, D. and Coc, A. and Kiener, J. and Tatischeff, V. and Thibaud, J. P. and Iwasa, N. and Kohlmeyer, B.},
abstractNote = {The possibility that big-bang nucleosynthesis (BBN) may produce nontrivial amounts of 6Li is under study since the recent observations of this element in old halo stars. However, the interpretation of these observations needs a precise knowledge of the reaction rate of D({alpha}, {gamma})6Li which, at present, is extremely uncertain (a factor of 20) at the energies of astrophysical interest (Ecm {<=} 300 keV). This uncertainty originates from difficulties in both theoretical estimates and experimental determinations of the D({alpha}, {gamma})6Li capture reaction cross section. New measurements of the cross section of D({alpha}, {gamma})6Li reaction using Coulomb dissociation of 6Li at 150 A MeV have been performed recently at GSI. The results will be compared to previous measurements and theoretical calculations.},
doi = {10.1063/1.2200893},
journal = {AIP Conference Proceedings},
number = 1,
volume = 831,
place = {United States},
year = {Wed Apr 26 00:00:00 EDT 2006},
month = {Wed Apr 26 00:00:00 EDT 2006}
}
  • Recent Wilkinson Microwave Anisotropy Probe (WMAP) measurements have determined the baryon density of the Universe {omega}{sub b} with a precision of about 4%. With {omega}{sub b} tightly constrained, comparisons of Big Bang nucleosynthesis (BBN) abundance predictions to primordial abundance observations can be made and used to test BBN models and/or to further constrain abundances of isotopes with weak observational limits. To push the limits and improve constraints on BBN models, uncertainties in key nuclear reaction rates must be minimized. To this end, we made new precise measurements of the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He total cross sections atmore » lab energies from 110 to 650 keV. A complete fit was performed in energy and angle to both angular distribution and normalization data for both reactions simultaneously. By including parameters for experimental variables in the fit, error correlations between detectors, reactions, and reaction energies were accurately tabulated by computational methods. With uncertainties around 2%{+-}1% scale error, these new measurements significantly improve on the existing data set. At relevant temperatures, by using the data of the present work, both reaction rates are found to be about 7% higher than those in the widely used NACRE (nuclear astrophysics compilation of reaction rates) database. These data will thus lead not only to reduced uncertainties, but also to modifications in the BBN abundance predictions.« less
  • The thermonuclear burning rates for the {sup 14}C({alpha},{gamma}){sup 18}O radiative capture reaction are calculated at temperatures (0.3{lt}{ital T}{lt}10 GK) of relevance to the early universe. These rates are particularly important for estimating the formation of heavy elements in an inhomogeneous big bang nucleosynthesis, proposed by Applegate, Hogan, and Scherrer (that would suggest the quark-gluon to hadron phase transition is first order). We investigate the effect of a possible new broad ({Gamma}{approx}0.45 MeV) 1{sup {minus}} state, at approximately 9.0 MeV in {sup 18}O as would be deduced from the Yale-Michigan State University measurement of the beta-delayed alpha-particle emission of {sup 18}Nmore » and suggested by the Notre Dame-Caltech measurement of the nonresonant {sup 14}C({alpha},{gamma}){sup 18}O cross section. The gamma widths of the proposed broad state is estimated using the Alhassid, Gai, and Bertsch sum rule, and an experimental study is proposed.« less
  • The recently claimed observations of non-negligible amounts of {sup 6}Li in old halo stars have renewed interest in the Big Bang nucleosynthesis (BBN) of {sup 6}Li. One important ingredient in the predicted BBN abundance of {sup 6}Li is the low-energy {sup 2}H({alpha},{gamma}){sup 6}Li cross section. Up to now, the only available experimental result for this cross section showed an almost constant astrophysical S factor below 400 keV, contrary to theoretical expectations. We report on a new measurement of the {sup 2}H({alpha},{gamma}){sup 6}Li reaction using the breakup of {sup 6}Li at 150 A MeV. Even though we cannot separate experimentally themore » Coulomb contribution from the nuclear one, we find clear evidence for Coulomb-nuclear interference by analyzing the scattering angular distributions. This is in line with our theoretical description, which indicates a drop of the S{sub 24} factor at low energies as predicted also by most other models. Consequently, we find even lower upper limits for the calculated primordial {sup 6}Li abundance than before.« less
  • The cross section from np -> dy is calculated at energies relevant to big-bang nucleosynthesis using the recently developed effective field theory that describes the two nucleon sector. The E1 amplitude is computed up to N{sup 3}LO and depends only upon nucleon-nucleon phase shift data. In contrast, the M1 contribution is determined by the cross section for cold neutron capture. The uncertainty in the calculation for nucleon energies up to E{approx}1 MeV is estimated to be <= 4%.
  • The cross section for np{yields}d{gamma} is calculated at energies relevant to big-bang nucleosynthesis using the recently developed effective field theory that describes the two-nucleon sector. The E1 amplitude is computed up to N{sup 3}LO and depends only upon nucleon-nucleon phase shift data. In contrast, the M1 contribution is computed up to next-to-leading order, and the four-nucleon-one-magnetic-photon counterterm that enters is determined by the cross section for cold neutron capture. The uncertainty in the calculation for nucleon energies up to E{approx}1 MeV is estimated to be (less-or-similar sign)4%. (c) 1999 The American Physical Society.