Investigation of the Early Stage of the Explosive Hydrogen Burning in the Universe

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Under the present project, a low-energy RI beam separator, CRIB has been developed, which has been successfully providing a unique opportunity to investigate the stellar reactions under explosive burning that involve unstable nuclei for the first time in Japan. A summary of the accomplishment of the works performed in the present is described below :(1)The low-energy RI beam in-flight separator, CRIB that has a configuration of QMDQDMQ+WF, has been developed mainly for pursuing the present project. Here, WF is a velocity filter to purify the RI beams. This system, for instance, has successfully provided an ^<14>O beam of more than 10^6 pps with nearly 100 % purity.(2)One of the most critical stellar reactions for the onset of the explosive hydrogen burning under high temperature and high-density condition, ^<14>O(α,p)^<17>F, was successfully investigated for the first time, confirming roughly the previous theoretical prediction that this reaction is the onset process for the X-ray burs … More t.(3)Another experiment is a study of proton resonances important for ^<11>C(p,γ)^<12>B, which locates at the breakout point from the hot-pp chain in the first generation stars. A new spin-parity assignment has been made for a resonance, identifying the importance of the level for the astrophysical reaction at high temperatures.(4)A series of proton resonance searches have been made for the early stage of the rp-process with RI beams of ^<21>Na, ^<22>Mg,^<23>Mg, ^<25>Al and ^<26>Si from CRIB, identifying new resonances in all systems studied here.(5)Resonant states, relevant to the hot-CNS cycle, were investigated for the 13N(p, g)14O stellar reaction with a 13N beam, confirming very dearly a single particle state predicted long. This resonance will affect the reaction rate at high temperature condition.(6)A high-resolution magnetic spectrograph has been developed for nuclear astrophysics project. A method of high resolution measurements has been developed including the tuning of the Cyclotron, the beam line and the spectrograph, giving about 40 keV for 104 MeV a-beam.. Less