Development of seven-dimensional detector system for low-energy light heavy-ions and its application to research on nuclear data of astrophysical interest

点击翻译按钮获取中文摘要

A new focal plane detector system for a recoil mass separator at Kyushu University tandem accelerator laboratory, designed to be capable of obtaining information of light heavy-ions with energies of less than 1 MeV/u on two-dimensional inclined angles and positions on the focal plane, energy, mass number and atomic number simultaneously, has been developed. The system consists of a solid state detector (SSD) and two two-dimensional position sensitive microchannel plates (MCPs) to detect ion-induced electrons from thin foils located in front of the SSD.The SSD with large active area was in beginning planned to be adopted to realize long flight pass for the measurement of time-of-flight. However, the performance test of the SSD with large active area using beams from the tandem accelerator has revealed significant dependence of pulse height deficit on the atomic number of the measured particles even in the range of atomic numbers less than 10, which has not been observed for the SSDs with relatively small active area. These findings imposed change of the design of the detection system to place the SSD with small active area at focal plane.We adopted a particle identification method using the emission yield of electrons from the downstream foil. Homogeneity of commercial foils was tested using a ^<12>C beam from the tandem accelerator and found that the Mylar foil has inhomogeneity of less than 3%. With this foil, the atomic number resolution has been estimated for 0.2 and 0.5 MeV/u ^<16>O to be 0.2 and 0.1, respectively, taking the energy straggling into account.The performance test of the whole system is now in progress and a trial to determine the ^4He(^<12>C,^<16>O)γ reaction rate at stellar energies using the separator and the detector system is about to start.