The 7-decays of levels in 26Mg have been investigated up to 12.5 MeV excitation energy by proton-7-ray coincidence measurements in the Z3Na(0~,pT) reaction at 14.2 and 16 MeV bombarding energy. Lifetime-measurements, made with the Doppler-shift attenuation method, and proton-7-ray angular-correlation measurements were performed at E,= 14.2 MeV. Many high-spin states were observed, among them levels at 6,978989(6 +) and 12,479(8 +, 7-) keV excitation energy. The spectrum of positive-parity states and their electromagnetic properties are reproduced with good accuracy by shell-model calculations which employ a unified s-d shell Hamiltonian and the unrestricted configuration space of the 0ds/2-1s1/2-0d3/~ shell. Members of five inferred rotational bands, with K~= 0 +, 2 +, 3 +, 0 + and 3-have been observed up to at least I= 6. The K~= 2 + band shows strong anomalies of excitation energies and E2 transition rates near the I= 6 state. The static intrinsic quadrupole moments calculated from the shell model wave functions indicate transitions from prolate to oblate deformation within the K~= 2 + band and also the ground state band. The lowest lying U =4 +. state appears to be "spherical" and cannot be associated with a rotational band.

A search for high-spin states in 288i has been performed by n-7 coincidence measurements in the 25Mg(e, nT) reaction at E~= 14 and i5.5 MeV. Spin-parity assignments of the observed levels were obtained from n-7 angular correlation and lifetime measurements at E~= 14.5MeV. The ?,-decay of the 9,t64keV level was investigated separately with the 27Al(p,?,) reaction at the Ep=2,160 and 2,312keV resonances. Rotational bands with K~=3 -(comprising levels at E~=6,879, 8,413, 10,188 and 12,204keV), K ~ = 5-(comprising levels at E~ =9,702, 11,577 and 13,741 keV) and K ~ =0 + (comprising levels at E~=6,691, 7,381, 9,164 and ll,509keV) were observed. The finding of the latter band supports the idea of coexisting oblate and protate shapes in zsSi. A level at 14,643keV excitation energy has the properties of the I~=8 + member of the ground state band. There are additional positive-parity high-spin states which do not fit into rotational bands. All types of positive-parity states are well accounted for by shell model calculations.

Abstract. The 42Ca levels at 4,715 and 6,633 keV excitation energy have been investigated using the 39K(~, py) reaction at E~--14 and 15 MeV. From particle-7-ray angular correlations the spin assignments J(4,715)--6, 4 and J(6,633)= 8, 6, 4 have been obtained. Lifetime measurements using the Doppler-shift attenuation method yielded ~(4,715)= 120_+46 fs and z (6,633)= 52_ 21 fs. Both levels have positive parity and decay by enhanced E 2 transitions. They are interpreted as the J~= 6 + and 8 + members, respectively, of the K ~ =0-:-rotational band which has the E x--1,837, 2,423 and 3,250 keV states as further members.

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Highly excited states in 3~ were investigated using the 2VAl(~, p 7) reaction. Proton-7 ray angular correlations were measured at E~=12, 14.1 and 15MeV. At 15MeV linear polarizations of 7-rays were measured in coincidence with protons using a five-crystal Compton-polarimeter. Lifetimes were measured at E~= 14.6 MeV using the Dopper-shift attenuation method. Unambigious spin-parity assignments were obtained for the levels at 6,865 (3+), 7,001 (5+), 7,079 (3+), 7,810 (4), 9,371 (6+), 7,613 (4-), 8,196 (5-), 8,596 (4-), 8,963 (5), 9,111 (6-), 9,350 (4-), 9,507 (5), 9,777 (6-), 10,188 (5), 10,305 (3-), 10,561 (6-), 10,725 (7-), 11,477 (6-) and 11,544 (7-)keV excitation energy, respectively. The structure of 3~ is understood both in terms of the shell model and the collective model. The levels at 5, 487, 6,505, 8,196, 9,777 and 11,544keV, respectively, are the l~=3-through 7-members of a well developed K ~ = 3-rotational band with intrinsic quadru-__ +250 pole moment IQol=350 70rob. There is evidence of further rotational bands, among them a K ~ = 5 -band with I Qol = 800 + 422 rob.-80