Performance of the Gas-jet Transport System Coupled to the RIKEN Gas-filled Recoil Ion Separator GARIS for the ²³⁸U(²²Ne, 5n)²⁵⁵No Reaction

Abstract

The performance of the gas-jet transport system coupled to the RIKEN gas-filled recoil ion separator GARIS was investigated using ²⁵⁵No produced in the ²³⁸U(²²Ne, 5n)²⁵⁵No reaction. Alpha particles of ²⁵⁵No separated with GARIS and transported by the gas-jet system were measured with a rotating wheel apparatus for α spectrometry under low background condition. The high gas-jet efficiencies of about 75% were independent of the recoil ranges of ²⁵⁵No in the gas-jet chamber. The present results suggest that the GARIS/gas-jet system is a promising tool for the next-generation superheavy element chemistry: (i) the background radioactivities of unwanted reaction products are strongly suppressed, (ii) the intense beam is absent in the gas-jet chamber and hence the high gas-jet efficiency is achieved, and (iii) the beam-free condition also allows for investigations of new chemical systems