Mass excess and excited states of neutron-rich silicon, phosphorus and sulphur isotopes

Abstract

The neutron-rich nuclei 33Si, 34Si, 35Si, 35p, 36p, 37 S and 3sS were investigated by studying ~4C and asO -induced transfer reactions on 36S using a Q3D magnetic spectrograph and a position sensitive focal plane gas detector. The previously unknown mass of the isotope 35Si was determined. The accuracy of the mass excess values of the isotopes 33Si, 34Si. 35p and 36p has been improved. Excited states of the isotopes 33Si, 34Si ' 35p, 36p and 38S were identified for the first time. In addition the v-decay of excited states in 37S and 3sS was studied with a Ge(Li) detector in coincidence with the Q3D focal plane detector. Experimental values for the mass excesses are compared with published mass formulae.

Use of the64Ni(36S,34,35Si)66,65Zn reactions to measure the masses of34Si and35Si

“…Table 1 presents a comparison of the present measurements with previous mass determinations. The mass measurements of Fifield et al [6] and Mayer et al [5] are in disagreement while the present mass measurement lies approximately mid-way between these two values.…”

“…Figure 4 presents the measured position spectrum of 38S15+ ions. It may be seen that the ground-state group is well resolved from the peak at 1.29 MeV which presumably corresponds to the population of the first excited state of 38S, previously identified by Mayer et al [5] at 1.296 MeV. The third intense peak in the spectrum of Fig.…”

“…The third intense peak in the spectrum of Fig. 4 at an excitation energy of 2.74 MeV corresponds to the population of the 2.83 MeV excited state of ass [5]. The latter two peaks may also include contributions from the population of excited states of 62Ni.…”

“…For 34Si the first measurement of mass excess was reported by Nathan and Alburger [7]. More recently, measurements of higher precision have been reported by Mayer et al [5] using the reaction 36S (14C, 160)34Si, by Woods et al [8] using the reaction 64Ni(36S, 34Si)66Zn and by Fifield et al [6] using the reaction 368 (11B, 13N)34Si"…”

“…For the isotopes of silicon the mass model predictions of Garvey and Kelson [1,2] updated by Jfinecke [3] indicate that the heaviest stable isotope is 468i, wherePresent address: National Superconducting Cyclotron Laboratory, Michigan State University, MI 48824, USA 2 Now at Department of Physics, Birmingham University, Birmingham B15 2TT, United Kingdom as particle stability has been established [4] for neutron-rich isotopes with A<_39. The mass-excess of 35Si has recently been determined by Mayer et al [5] using the reaction 36S(14C, 150)3sSi. For 34Si the first measurement of mass excess was reported by Nathan and Alburger [7].…”