2 research outputs found
Breakup of loosely bound nuclei as indirect method in nuclear astrophysics: 8B, 9C, 23Al
We discuss the use of one-nucleon breakup reactions of loosely bound nuclei
at intermediate energies as an indirect method in nuclear astrophysics. These
are peripheral processes, therefore we can extract asymptotic normalization
coefficients (ANC) from which reaction rates of astrophysical interest can be
inferred. To show the usefulness of the method, three different cases are
discussed. In the first, existing experimental data for the breakup of 8B at
energies from 30 to 1000 MeV/u and of 9C at 285 MeV/u on light through heavy
targets are analyzed. Glauber model calculations in the eikonal approximation
and in the optical limit using different effective interactions give
consistent, though slightly different results, showing the limits of the
precision of the method. The results lead to the astrophysical factor
S_17(0)=18.7+/-1.9 eVb for the key reaction for solar neutrino production
7Be(p,\gamma)8B. It is consistent with the values from other indirect methods
and most direct measurements, but one. Breakup reactions can be measured with
radioactive beams as weak as a few particles per second, and therefore can be
used for cases where no direct measurements or other indirect methods for
nuclear astrophysics can be applied. We discuss a proposed use of the breakup
of the proton drip line nucleus 23Al to obtain spectroscopic information and
the stellar reaction rate for 22Mg(p,\gamma)23Al.Comment: 6 pages, 4 figures. Presented at the conference "Nuclear Physics for
Astrophysics 2", Debrecen, Hungary, May 2005. Prepared for the Proceeding
Structure of (23)Al from the one-proton breakup reaction and astrophysical implications
The ground state of the proton-rich nucleus 23Al has been studied by
one-proton removal on a carbon target at about 50 MeV/nucleon using the EXOGAM
+ SPEG experimental setup at GANIL. Longitudinal momentum distributions of the
22Mg breakup fragments, inclusive and in coincidence with gamma rays
de-exciting the residues, were measured. The ground-state structure of 23Al is
found to be a configuration mixing of a d-orbital valence proton coupled to
four core states - 0, 2, 4, 4. We
confirm the ground state spin and parity of 23Al as . The
measured exclusive momentum distributions are compared with extended Glauber
model calculations to extract spectroscopic factors and asymptotic
normalization coefficients (ANCs). The spectroscopic factors are presented in
comparison with those obtained from large-scale shell model calculations. We
determined the asymptotic normalization coefficient of the nuclear system
Al Mg(0) + p to be
() = (3.90 0.44) 10
fm, and used it to infer the stellar reaction rate of the direct
radiative proton capture Mg(p,)Al. Astrophysical
implications related to Na nucleosynthesis in ONe novae and the use of
one-nucleon breakup at intermediate energies as an indirect method in nuclear
astrophysics are discussed.Comment: 8 pages, 4 figures submitted to PRC, March 2 201