A data analysis method for isochronous mass spectrometry using two time-of-flight detectors at CSRe

Abstract

The concept of isochronous mass spectrometry (IMS) applying two time-of-flight (TOF) detectors originated many years ago at GSI. However, the corresponding method for data analysis has never been discussed in detail. Recently, two TOF detectors have been installed at CSRe and the new working mode of the ring is under test. In this paper, a data analysis method for this mode is introduced and tested with a series of simulations. The results show that the new IMS method can significantly improve mass resolving power via the additional velocity information of stored ions. This improvement is especially important for nuclides with Lorentz factor γ-value far away from the transition point γt of the storage ring CSRe.

Experimental investigation of the transition energy γt in the isochronous mode of the HIRFL-CSRe

“…The mass resolving power can be significantly increased though at a cost of a dramatically reduced transmission. Third, one can correct the revolution time by measuring their velocities [32][33][34]. In principle, this method has a great advantage to improve the mass resolving power of IMS without losing valuable statistics.…”

“…The simulation results show that the new scheme can significantly improve mass resolving power with the additional velocity information of stored ions. This improvement is especially important for nuclei with γ value far away from the γ t [34]. X.L.…”

Improving the resolving power of Isochronous Mass Spectrometry by employing an in-ring mechanical slit

“…The timing signals were recorded directly by a high-performance digital oscilloscope Tektronix DPO 71254. For each injection the recording (sampling) time was set to 300 µs, to be compared to 200 µs in previous experiments [12,13,29]. The revolution times of each ion was extracted from the timing signals.…”

“…It is clear that due to a limited magnetic rigidity (Bρ = mvγ/q) acceptance of the ring, this condition is fulfilled for a limited range of m/q values. The narrow m/q region in which the isochronous condition γ t ≈ γ is roughly fulfilled is called the isochronous window [29]. Typically, the absolute value of phase-slip factor η, defined as 1/γ 2 t − 1/γ 2 , is as small as 10 −3 in the isochronous window and increases rapidly depending on the proximity of γ to γ t .…”

Characterization of a double Time-Of-Flight detector system for accurate velocity measurement in a storage ring using laser beams

“…A novel way to increase R without reducing the acceptance of the ring was first proposed at GSI in 2005 [42,43]. The idea is to measure the velocity for each stored ions with two TOF detectors in the ring such that the revolution time spread can be reduced by using the velocity information in the off-line data analysis [44][45][46][47]. In this way, the resulting mass resolving power can be improved for all the stored ions over a large m/q-range and the systematic error caused by the second term in Eq.…”