rp-Process Nucleosynthesis at Extreme Temperature and Density Conditions
H. Schatz, A. Aprahamian, J. Goerres, M. Wiescher, T. Rauscher, J.F. Rembges,
F.-K. Thielemann, B. Pfeiffer, P. Moeller, K.-L. Kratz, H. Herndl, B.A.
Brown, H. Rebel;
Phys. Rep. 294 (1998) 167
Abstract:
We present nuclear reaction network calculations to investigate the
influence of nuclear structure on the rp-process between Ge and Sn in
various scenarios. Due to the lack of experimental data for
neutron-deficient nuclei in this region, we discuss currently available
model predictions for nuclear masses and deformations as well as methods
of calculating reaction rates (Hauser-Feshbach) and beta-decay rates
(QRPA and shell model). In addition, we apply a valence nucleon
(N_p,N_n) correlation scheme for the prediction of masses and
deformations. We also describe the calculations of 2p-capture reactions,
which had not been considered before in this mass region. We find that
in X-ray bursts 2p-capture reactions accelerate the reaction flow into
the Z>=36 region considerably. Therefore, the rp-process in most X-ray
bursts does not end in the Z=32-36 region as previously assumed and
overproduction factors of 10^7-10^8 are reached for some light p-nuclei
in the A=80-100 region. This might be of interest in respect of the yet
unexplained large observed solar system abundances of these nuclei.
Nuclei in this region can also be produced via the rp-process in
accretion disks around low mass black holes. Our results indicate that
the rp-process energy production in the Z>32 region cannot be neglected
in these scenarios. We discuss in detail the influence of the various
nuclear structure input parameters and their current uncertainties on
these results. It turns out that rp-process nucleosynthesis is mainly
determined by nuclear masses and beta-decay rates of nuclei along the
proton drip line. We present a detailed list of nuclei for which mass of
beta-decay rate measurements would be crucial to further constrain the models.
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