Intermediate-energy Coulomb excitation ofSn104: ModerateE2strength decrease approaching

Abstract

The reduced transition probability B(E2)↑ of the first excited 2 + state in the nucleus 104 Sn was measured via Coulomb excitation in inverse kinematics at intermediate energies. A value of 0.173(28) e 2 b 2 was extracted from the absolute cross section on a Pb target. Feeding contributions in 104 Sn from higher lying states were estimated by a reference measurement of the stable 112 Sn. Corresponding only to a moderate decrease of excitation strength relative to the almost constant values observed in the proton-rich, even-A 106−114 Sn isotopes, present state-of-the-art shell-model predictions, which include proton and neutron excitations across the N = Z = 50 shell closures as well as standard polarization charges, underestimate the experimental findings.

Lifetime measurement of the41+state ofNi58with the recoil distance method

“…Recent progress in Coulomb excitation and lifetime measurements with rare isotope beams has provided B(E2) data for well deformed nuclei with N =40-50 [1] [2][3] [4] and in the vicinity of doubly-magic nuclei 56 Ni and 100,132 Sn, away from the valley of stability [5][6] [7] [8]. Concurrently, the development of new effective interactions in model spaces with larger dimensions has expanded the shell model's predictive power into heavier mass regions, including a new frontier around A ≈ 60-80 at the pf shell extending into the sdg shells [9][10] [11].…”

Z=50core stability inSn110from magnetic-moment and lifetime measurements

“…The reduced transition probability data in 104−134 Sn ( [1][2][3][4][5][6][7][8][9][10] and references therein), follow only above midshell (A = 116) the * Electronic address: kum@physics.rutgers.edu parabola-like curve of the shell model expectations [6]. For nuclei below midshell the B(E2) values are larger than expected but finally decrease at N = 54, as the doubly-closed shell Z = N = 50 is approached.…”

Novel Shape Evolution in Sn Isotopes from Magic Numbers 50 to 82

“…E2 transition probabilities are direct indicators of the deformation from a sphere to an ellipsoid, and are quantified through B(E2) values [1,10]. For Sn isotopes, anomalous deviations from the spherical picture were observed for the B(E2; 0 + 1 → 2 + 1 ) value as a function of N [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], but a unified theoretical description of these anomalies is missing. In this Letter, we present, for the first time, results of state-of-the-art calculations with the Monte Carlo Shell Model (MCSM) [32,33] on Sn isotopes, performed in a large model space including singleparticle orbits below and above the magic numbers 50 and 82.…”