Dresden 2000 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 10: Kernphysik / Spektroskopie II

HK 10.3: Talk

Monday, March 20, 2000, 17:15–17:30, B 68

Structure of medium-mass odd-odd nuclei close to the N=Z line — •J. Döring and ISOL Group — GSI Darmstadt, Planckstr. 1, D-64291 Darmstadt

The enlarged spatial overlap of proton and neutron wave functions in N=Z nuclei results in an increased probability for proton-neutron pairing, an interesting coupling mode predicted by various theories [1], but so far verified experimentally not conclusively for medium-mass nuclei. Thus, there is a quest to study low-lying states with isospin T = 0 and 1 in the odd-odd nuclei ⁶²Ga, ⁶⁶As, ⁷⁰Br, and ⁷⁴Rb which are known to exhibit short-lived, I^π= 0⁺, T = 1 ground states. Experiments have been performed at the GSI on-line mass separator (ISOL) to search for long-lived (T_1/2 > 80 ms) isomeric states. The ⁶²Ga and ⁷⁰Br nuclei have been produced via the ²⁸Si(³⁶Ar,pn) and ⁴⁰Ca(³⁶Ar,αpn) reactions, respectively, with production rates of about 1200 and 100 atoms/s. Singles γ-ray spectra and β-γ-γ coincidences have been measured. Furthermore, the decay of the 12⁺ isomer (T_1/2 = 46 s) in the N=Z ⁵²Fe nucleus has been investigated at ISOL with the goal to identify the direct γ-decay branch to states in ⁵²Fe, besides the dominating β⁺/EC decay to excited states in ⁵²Mn [2]. The results of all these measurements will be reported and complemented by recent results obtained from the β decay of the N = Z + 2 nucleus ⁸⁴Nb to low-lying states in ⁸⁴Zr [3]. The consequences for nuclear structure physics and future experiments will be discussed.

[1] A. L. Goodman, Phys. Rev. C 60, 014311 (1999)

[2] D. F. Geesaman et al., Phys. Rev. C 19, 1938 (1979)

[3] J. Döring et. al., submitted to Phys. Rev. C