Speaker
Description
Radioactive isotope (RI) beams broaden our scope for
understanding the nature of exotic nuclei.
RI are rarely found on the earth, but can be artificially produced using
accelerated beams and special apparatuses.
One example is CRIB, an RI-beam separator of Center for Nuclear Study, the University of Tokyo,
installed in the RIBF of RIKEN Nishina Center.
It can produce low-energy (less than 10 MeV/u) RI beams
at a relatively high intensity by the in-flight method.
Recent experimental projects include:
1) Simulations of X-ray bursters have indicated that the
RI-involving nuclear reaction rates could significantly affect the
profile of the observed X-ray light curve.
Experiments to evaluate the astrophysical reactions
in the region of proton-rich nuclei have been conducted at CRIB,
such as those for the 22Mg(alpha, p) and 26Si(alpha, p) reactions.
2) The primordial lithium abundance in the Big-Bang nucleosynthesis (BBN)
still shows a discrepancy between the values by the stellar observation and by
the simulation based on the standard Big-Bang model.
To study the beryllium-7 destruction process, we studied 7Be+n reactions
using the Trojan-horse method. This project was in a deep collaboration between
Italy and Japan.
3) Alpha-clustering is a special phenomenon often found in nuclear
excited states around the alpha-particle threshold.
There has been prediction of linear-chain cluster states, in which alpha particles
are linearly aligned in the nucleus, as an exotic form of alpha-clustering.
Search for the linear-chain states have been performed at CRIB, for the
nuclei of 14C and 14O.
The latest experimental achievements of these subjects are introduced and discussed.