Direct mass measurements of neutron-rich ⁸⁶ Kr projectile fragments and the persistence of neutron magic number N =32 in Sc isotopes

Abstract

In this paper, we present direct mass measurements of neutron-rich 86 Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry (IMS) method. The new mass excesses of 52−54 Sc nuclides are determined to be -40492(82), -38928(114), -34654(540) keV, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012 (AME12). In particular, 53 Sc and 54 Sc are more bound by 0.8 MeV and 1.0 MeV, respectively. The behavior of the two neutron separation energy with neutron numbers indicates a strong sub-shell closure at neutron number N = 32 in Sc isotopes.

Precision mass measurements of Fe67 and Co69,70 : Nuclear structure toward Cañete1, Giraud2, Kankainen3 et al. 2020Phys. Rev. C

“…The determined mass-excess value for 69 Co, −50 383(44) keV agrees well with the most recent Atomic Mass Evaluation (AME16) [67] value based on measurements using the TOFI spectrometer [68,69], Bρ-TOF method [70,71], and isochronous mass spectrometry [72]. The obtained mass-excess value for the isomer 69 Co m , −50 207(36) keV is in perfect agreement with the ground-state value of −50 214( 14) keV [25], reported recently from the LEBIT Penning trap, suggesting they have actually measured the isomer.…”

Quenching of the N=32 neutron shell closure studied via precision mass measurements of neutron-rich vanadium isotopes

“…In this region Penning-trap mass measurements by ISOLTRAP [11,12] and TITAN [13] show strong shell effects in neutron rich 19 K and 20 Ca isotopes at N = 32. Similar behavior has been seen for 21 Sc in mass measurements at the CSRe storage ring [14]. Recent work at TITAN [15] showed the transitional behavior in the 22 Ti isotopic chain along the N = 32 isotone in comparison to state-of-the-art ab initio shell model calculations.…”

Charge resolution in the isochronous mass spectrometry and the mass of $$^{51}$$Co

“…A lower number of stored ions in an individual injection will also lead to a higher resolution. Two timing detectors, a new IMS method that is under development and which will be applied in future experiments at the CSRe [12,29,[38][39][40][41], could also increase the charge resolution. Finally, MCP plates with 2 lm of pore size will be adopted, thus boosting the number of microchannels.…”

“…Using IMS at the CSRe, we measured the masses of more than 30 short-lived nuclei [22][23][24][25][26][27][28][29][30][31][32]. For a recent review, the reader is referred to Refs.…”

“…A higher charge resolution is desired. For example, the masses of 54;56 Ti nuclides were measured in an earlier experiment at the CSRe [23,29]. The 55 Ti nuclide must have been produced in significant amounts in this experiment according to the yields of the neighboring nuclei; however, it could not be separated from 50 Ca.…”