Construction of He-jet system

Shell model calculations have shown that delayed protons in a highly excited state of 37K with a high Gamow-Teller instensity are easily fed to the first excited state of 36Ar (2+, 1970keV). A He-jet transport system is installed in the SF cyclotron facility at the Institute for Nuclear Study, University of Tokyo, with the aim of investigating the amount of delayed protons fed to the 2+ first excited state. Observations are made of the spectrum of delayed proton from 37Ca (T2/1=175msec) using a Si(Li) detector and coincidence spectrum with gamma rays using a NaI detector. The He-jet transport system comprises a recoil atom collecting portion, which has a structure similar to the RAMA-type and SARA-type systems, and an aerosol production portion, which has a structure similar to the KUR-ISOL system. Performance test is carried out using CaF2 (1mg/cm2) or Ca metal as target. Spectra of delayed protons and alpha particles obtained with the CaF2 target are shown and discussed. The 37Ca delayed proton spectrum and coincidence spectrum with 35Ar 1970keV gamma rays are also observed and discussed. Results indicate that the system can show a satisfactory performance. (N.K.)