6Department of Physics, Tsukuba University, Tsnkuba 90o"-8571, Japan 7thculty of Science, Ydmagata University, YILmagata 990-8560, Japan 8Department of Physics, Uftiversity of MeMaster, Canada 9 Uitiversita di Catania and INFAJLLNS, Catania, Italy iODepartment of Physies, Seoul National Uhiversity, Seonl, Korea 'L'iEwha Womans' University, Seout, Korea i2institute of Modern Physics, Lanzhou, China i3Department of Physics, C7L?mg Ang Uhiversity, Seoul, Korea i4Max-Planck-lastitut ftir Astrophysik, D-85748 Garching, Gerrnany

The role of nuclear clustering in stellar reactions is discussed, with Cluster Nucleosynthesis Diagram (CND) proposed before, for nucleosynthesis in stellar evolution and explosive stellar phenomena. Special emphasis is placed on α-induced stellar reactions. We report here the first experimental evidence that a cluster resonances dominate the (α,p) stellar reaction cross sections that is crucial for the vp-process in core-collapse supernovae.

Nucleosynthesis is one of the keys in studying the mechanism of core-collapse supernovae, which is an interesting challenge for modern science. The νp-process, which is similar to an explosive hydrogen burning process, has been proposed as the most probable process in the very early epoch of type II supernovae. Here, we discuss our experimental efforts for the νp-process, the first extensive direct measurements of the (α,p) reactions on bottle-neck proto-rich nuclei in light mass regions. Other challenges for the νp-process study are also discussed.

Astrophysical stellar reactions at extremely high temperatures involve a variety of problems both in nuclear reactions and nuclear structures. Specifically, the problems in the nu p-process were discussed in this talk based on our recent experimental results with low-energy RI beams and a simulation study. The nu p-process is one of the key processes for investigating the mechanism of type II supernovae, and the process could be possibly responsible for "the excess production" of p-nuclei around mass 90-100. Alpha cluster resonances have been discovered experimentally to play a crucial role for the stellar (alpha, p) reactions just above the alpha threshold. Neutron induced reactions in the proton-rich nuclear regions in the nu p-process are also suggested to play an important role, which involve nuclear structures of high level density at high excitation energies, probably giant resonances. The discussion also covered the p-nuclei production through the nu p-process at around mass 100.

1Center for Nuclear Study, University of Tokyo, Wako 351-0198, Japan 2Institute of Physics, VAST, Hanoi, Vietnam 3Japan Atomic Energy Agency, Tokai, Ibaraki 351-1195, Japan 4Department of Physics, Kyushu University, Fukuoka 812-8581, Japan 5Department of Physics, Tohoku University, Sendai 980-8578, Japan 6Department of Physics, Tsukuba University, Tsukuba 305-8571, Japan 7Faculty of Science, Yamagata University, Yamagata 990-8560, Japan 8Department of Physics, University of McMaster, Canada 9Universita di Catania and INFN-LNS, Catania, Italy 10Department of Physics, Seoul National University, Seoul, Korea 11Ewha Womans’ University, Seoul, Korea 12Institute of Modern Physics, Lanzhou, China 13Department of Physics, Chung Ang University, Seoul, Korea 14Max-Planck-Institut fur Astrophysik, D-85748 Garching, Germany

Nucleosynthesis by alpha particles and heavier 4n nuclei are of great interest as they would involve nuclear cluster resonances. The role of nuclear clustering is discussed for nucleosynthesis with the Cluster Nucleosynthesis Diagram (CND) proposed before, especially those involving alpha induced reactions, based on our recent works of (alpha,p) reactions with low energy RI beams. We present experimental results that alpha resonances play a crucial role for the (alpha,p) reaction cross sections. Molecular resonances are also briefly discussed along this line for O- and C-burning.

After a brief review on low-energy RI beam production technology, nuclear astrophysics programs at CNS are presented including a scope of the field in the Wako campus. The CRIB project involves a total development of the whole facility to maximize the low-energy RI beam intensities, including the ion source, the AVF cyclotron and the low-energy RI beam separator CRIB. Some recent nuclear astrophysics experiments performed with the RI beams were discussed, including the measurement of the 140(a,p) 17 F reaction, the key stellar reaction for the onset of the high-temperature rp-process. The first experiment performed with a newly installed high-resolution magnetic spectrograph PA of CNS was also presented. Collaboration possibilities for nuclear astrophysics in the RIKEN campus are also touched.