Speaker
Description
A novel isochronous mass spectrometry, termed B$\rho$-defined IMS, has been established at the experimental cooler-storage ring CSRe in Lanzhou. It used two time-of-flight detectors installed in one of the straight sections of CSRe, thus enabling simultaneous measurements of the velocity and the revolution time of each stored short-lived ion [1]. This allows for calculating the magnetic rigidity B$\rho$ and the orbit length C for the well-known mass nuclei, giving a universal calibration curve, i.e., B$\rho$(C) function, which is then used to deduce the masses of all stored nuclides [2,3]. In the limiting case of just a single particle, the achieved mass resolving power allows one to determine its mass-over-charge ratio m/q with a remarkable precision of merely ∼ 5 keV. Mass measurements of several very neutron-deficient $sd$- and $fp$-shell nuclides from fragmentation of $^{36}$Ar, $^{58}$Ni, and $^{78}$Kr have been performed using the B$\rho$-defined IMS. New mass results and their impact on some issues in nuclear structure and nuclear astrophysics are presented and discussed [4-7].
References:
[1] X. Zhou et al., In-ring velocity measurement for isochronous mass spectrometry, Phys. Rev. A&B 24, 042802 (2021)
[2] M. Wang et al., B$\rho$-defined isochronous mass spectrometry: An approach for high-precision mass measurements of short-lived nuclei, Phys. Rev. C 106, L051301 (2022)
[3] M. Zhang et al., B$\rho$-defined isochronous mass spectrometry and mass measurements of $^{58}$Ni fragments, Euro. Phys. Jour. A59, 27 (2023)
[4] X. Zhou et al., Mass measurements show slowdown of rapid proton capture process at waiting-point nucleus $^{64}$Ge, Nat. Phys. 19, 1091 (2023)
[5] M. Wang et al., Mass measurement of upper $fp$-shell N = Z − 2 and N = Z − 1 nuclei and the importance of three-nucleon force along the N = Z line, Phys. Rev. Lett. 130, 192501 (2023)
[6] Y. Yu et al., Nuclear structure of dripline nuclei elucidated through precision mass measurements of $^{23}$Si, $^{26}$P, $^{27,28}$S, and $^{31}$Ar, Phys. Rev. Lett. 133, 222501 (2024)
[7] Y. M. Xing et al., Z = 14 magicity revealed by the mass of the proton dripline nucleus $^{22}$Si, Phys. Rev. Lett. 135, 012501 (2025)