PRECISE MEASUREMENT OF ASTRO-NUCLEAR RECTION USING RECOIL MASS ANALYZER

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The astro-nuclear reaction of ィイD14ィエD1He+ィイD112ィエD1C->ィイD116ィエD1O+γ at EィイD2cmィエD2 = 300 keV plays a very important role in the supernovae and in the primordial nuclear synthesis. In spite of experimental efforts in the world over 30 years, no precise experimental data have been obtained yet due to the extremely small cross section. In the present study, we have developed new instruments and methods in order to precisely measure the reaction cross section in the range from EィイD2cmィエD2 = 3 MeV to 700 keV.We adopted the inverse kinematics method. The detection of the reaction product ィイD116ィエD1O in this method is more than 100 times more efficient than the γ-ray detection so far adopted in many experiments. To separate ィイD116ィエD1O coming out in forward angle and the ィイD112ィエD1C-beam, we developed a recoil mass separator that is composed of one electric deflector, two magnetic deflectors, four quadrupole magnets, and four auxiliary multipole magnets.We also developed a new blow-in type windowless gas target which was found to have enough gas-confining power and to produce ideal gas distribution. Satisfactory target thickness is obtained by the blow-in gas target together with the gas cooling system.We succeeded in strong-focus beam acceleration by the new accel-decel method using Kyushu University tandem accelerator. In this success, we showed that the large tandem accelerator can be transformed to a small tandem with a little modification. we also succeeded in the development of a large aperture gas stripper. By the two successes, a low-energy beam necessary for the astro-nuclear experiment in creased more than 100 times in intensity. Moreover we have succeeded in the production of the pulse beam to be used for the background reduction.After the above developments, we have started the preliminary experiment for the measurement of the ィイD14ィエD1He+ィイD112ィエD1C->ィイD116ィエD1+γ reaction cross section.