Investigation Of The Isochronicity Correction Of The Spectrometry Ring(SRing) And The Storage Ring(CSRe)

Isochronous Mass Spectrometry (IMS) is a unique experimental method for massmeasurement experiments of short-lived nuclei. The masses of stored ions aremeasured by employing the IMS technique, which is based on the determination ofthe ion revolution time.The Spectrometry Ring (SRing) is one of the rings of the next generationaccelerator complex High Intensity Heavy Ion Accelerator Facility (HIAF) of theInstitute of Modern Physics of the Chinese Academy of Sciences. The SRing will beoperated as a time-of-flight mass spectrometer for short-lived nuclei. The SRingconsists of magnet system, injection/extraction components, stochastic cooling systemand detectors. It has the purpose of stochastic precooling of rare isotopes and ofmeasuring nuclear masses in an isochronous mode. In order to fulfil its purpose, theion optics can be set to different ion optical modes. This paper discusses theconsiderations of the injection/extraction strategies of these two different modes.However, the isochronicity, and thus the mass resolving power, depends on themomentum spread and the transverse emmittance of the injected beams. Here wepresent the first-order isochronicity optimization, the chromaticity and second-orderisochronicity corrections through the modification of the quadrupole and sextupolefield strengths. With the help of these corrections, a mass resolution of m/m106can be achieved.Mass measurements of78Kr projectile fragments were performed inHIRFL-CSRe at IMP. The short-lived secondary beams were produced bybombarding a15mm thick beryllium-target in the Radioactive Ion Beam Line(RIBLL2) and were then injected into the CSRe storage ring. A dedicatedtime-of-flight (TOF) detector is used for that purpose. A new optics is also present tofit the new mode of CSRe to fit the double TOF detector experiments.