Study of Nuclear Reactions For Astrophysics

The goals of this study were to investigate the nuclear structure of 26 Si in the energy region above the alpha threshold and thereaction rate of the stellar reaction 22 Mg(α,p) 25 Al . In this work, the excited states of 26 Si and reaction rate of the stellar reaction were experimentally studied for the first time via direct measurement of the reaction 22 Mg+α with the thick target method in inverse kinematic by using the RI beam of 22 Mg. The experimental technique was also an interest in the present work. It should be notedthat RI beam production of 22 Mg was concerned because it was difficult to produce a low-energy beam with high purity and intensity. This point was thought to be one of the reasons of no direct measurement performed until now. In addition, a new active target detector was developed for stellar reaction measurements with heavy projectiles. The experiment of 22 Mg+αreaction was performed at CRIB facility. The excitation function of cross sections of the scattering reaction 22 Mg(α,α) 22 Mg was measured with six resonances. Their energies, spins and parities were assigned successfully by the multichannel R-matrix method. There were six excited states in 26 Si corresponding to the six resonances. In which, three new levels at E r =11.245 ± 0.028, 11.493 ± 0.216, 11.807 ± 0.117 MeV and spinparities of three high level states at E r = 10.318 ±0.011, 10.678 ±0.016, 10.831 ± 0.113 MeV, which have unknown spin-parities, were assigned by this work for the first time. Because quantum parameters of all previous works were not obtained, the spin-parity determined in this work plays an important role to study properties of 26 Si as well as its mirror nucleus, 26 Mg. It should be noted that although the energy levels of 26 Mg are well-known, there are a lot of spinparities of the levels not assigned until now.

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