SCORPION - A SYSTEM FOR COINCIDENCES BETWEEN RECOIL AND PROJECTILE IONS AT NSC, NEW-DELHI

An on-line facility to measure coincidences between the recoil ions an d the scattered projectiles (SCORPION) has been designed, fabricated a nd commissioned at Nuclear Science Centre (NSC), New Delhi. The facili ty consists of a four jaw slit assembly, a time of flight (TOF) spectr ometer, a parallel plate electrostatic charge analyser and a one dimen sional position sensitive parallel plate avalanche counter (PPAC). Det ails of the design and working principles of various components and th e test results obtained for the Siq+-Ar collision system are presented to highlight the performance of the system. A multiple loss of up to four electrons has been observed for 60 MeV Si4+ ions colliding with a rgon atoms in a single collision condition. Spectra of recoil ions det ected in coincidence with a particular charge state of the scattered p rojectile show a bell shaped distribution as a function of the recoil charge state (r) for the electron loss events. However, the yield of r ecoil ions drops as r increases for the direct ionization channel. Als o for electron loss, the peak of the recoil ion distribution is seen t o shift to a higher recoil charge state as the number of lost electron s from the projectile increases.