The structure of25Mg

Gamma-decay modes and spin(-parity) assignments of levels in²⁵Mg have been systematically investigated up to 10 MeV excitation energy by particle-γ-ray angularcorrelation measurements with the²⁴Mg(d, pγ) reaction at 6.5 MeV bombarding energy and with the²²Ne(α,nγ) reaction at 11.8, 12.5, 14.4 and 15.5 MeV bombarding energy. A level scheme has been established which is comprehensive up to 8.3 MeV excitation energy forI≦9/2 and up to 10 MeV for 9/2O d _5/2 — 1s _1/2-O d _3/2 shell and the unifieds-d shell Hamiltonian. The agreement is good to excellent. The first intruder states are located near 6.8 MeV excitation energy. The collective properties of²⁵Mg beyond the well established rotational bands are investigated using both the new experimental information and theB(E2)'s obtained from the shell model. The spectrum of²⁵Mg is completely rotational for the first five to six MeV above the yrast line. Shell modelB (M 1)'s reflect the Nilsson model structure of²⁵Mg in great detail. The prospectiveI ^π=9/2^?, 13/2^?, and 15/2^? members of the established negative-parity,K=1/2 band are found in levels atE _x=7801, 9410, and 8896 keV.