Structure of high-spin states in89Srand90Sr

Abstract

High-spin states of 89 Sr and 90 Sr were studied via the reactions 82 Se( 11 B, p3n) and 82 Se( 11 B, p2n), respectively, at a beam energy of 37 MeV. Gamma rays were detected with the GASP spectrometer. The level schemes of 89 Sr and 90 Sr were extended up to EϷ8 MeV and EϷ10 MeV, respectively. Level structures in 89 Sr and 90 Sr were interpreted in terms of the spherical shell model. The calculations were performed in the configuration space (0 f 5/2 ,1p 3/2 ,1p 1/2 ,0g 9/2 ) for the protons and (1p 1/2 ,0g 9/2 ,1d 5/2 ) for the neutrons. Highspin level sequences in 89 Sr are characterized by coupling the unpaired d 5/2 neutron to proton excitations of the core nucleus 88 Sr. An equidistant level sequence with ⌬Jϭ2 found in 90 Sr is well described by the configuration ͓(0 f 5/2Ϫ2 )(0g 9/2 2 )͔(1d 5/2 2 ) favoring even spins.

Low-energy behavior ofE2strength functions

“…The calculations were performed by means of the code RITSSCHIL [24] using a model space composed of the π(0f 5/2 , 1p 3/2 , 1p 1/2 , 0g 9/2 ) proton orbits and the ν(1p 1/2 , 0g 9/2 , 1d 5/2 ) neutron orbits relative to a 66 Ni core. The configuration space was tested in detail in earlier shell-model studies of nuclei with N = 46 − 54 [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] and was found appropriate for the description of level energies as well as M 1 and E2 transition strengths in nuclides around A = 90. As a further test, a comparison of the energies of yrast and yrare levels in 94 Mo and 95 Mo from the present calculation with the experimental ones shows an agreement within 300 keV.…”

Low-Energy Enhancement of Magnetic Dipole Radiation

“…The shell-model calculations were performed by means of the code RITSSCHIL [22] using a model space composed of the π(0f 5/2 , 1p 3/2 , 1p 1/2 , 0g 9/2 ) proton orbits and the ν(0g 9/2 , 1d 5/2 , 0g 7/2 ) neutron orbits relative to a 68 Ni core. The configuration space was tested in detail in our earlier shell-model studies of nuclei with N = 46 − 54 [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] and was found appropriate for the description of level energies as well as M 1 and E2 transition strengths in nuclides around A = 90. As a further test, we compared the energies of yrast and yrare levels in 94,95,96 Mo and 90 Zr from the present calculation with the experimental ones, which agree within 300 keV.…”

Search for the $α$ + core structure in the ground state bands of $22 \leq Z \leq 42$ even-even nuclei

“…Ge, Se, Kr, and Sr: the nuclei 62 Ge, 64 Se, 70 Kr, and 74 Sr are those with the highest Q α /A T values in their respective isotopic chains. However, such nuclei have only the 0 + ground state known experimentally, or the states above 0 + have no defined spin and parity.…”