Abstract. New assignments of quantum numbers have been obtained for more than 50 levels in 2ssi between 8953 and 15915 keV excitation energy. They are based on the measurement of 7-ray angular distributions or anisotropics on 29 resonances of the 27Al(p,7) reaction and on the 24Mg(c~,7) resonance at E~ = 3355keV. A total of 15 high-spin states with I = 5-7 has been obtained and the spectrum of T = 1 states has been identified up to 15 915 keV excitation energy and a maximum spin I=6.

Abstract. The systematics of 7-decay modes and radiative widths of highly excited states in 28Si has been extended by taking 7-ray spectra on 60 resonances of the 27Al(p, 7) reaction in the range 1097keV_< E,_< 4492keV (12643 keV _< Ex _< 15915 keV) and on the 24Mg(e,7) resonances at E~ = 3355, 3431, 4003 keV (Ex = 12860, 12925, 13415 keV). The y-decay modes of levels in the sub-resonance region (Ex = 10-12.5 MeV) were studied with both the 27Al(p, 7) reaction and the 27Al(d, nT) reaction at Ee = 4, 5, 6 MeV. Information on radiative widths of levels was obtained by measuring the resonance strengths S 7 = (2I + 1)FpF~fF for 52 resonances of the 27Al(p, 7) reaction with an emphasis on prospective T = 1 states.

The properties of positive-parity states in 32 S are compared to predictions of shell model calculations within the complete s-d basis space using the universal s-d shell Hamiltonian. The experimental T = O spectrum is reproduced to excitation energies between 10 and 11.7 MeV, depending on the level spins. The T = 1 spectrum is known and reproduced for the first five 5 MeV in excitation in general and for the first 8 MeV in the case of I π = 1 + states. Altogether the excitation energies of 80 positive-parity states are reproduced with a rms deviation of 200 keV. A calculation of radiative widths and branching ratios for γ-decay which uses effective charges and free-nucleon g-factors yields good general agreement with experiment. The need for effective g-factors is felt only in the rare cases of transitions which are governed by the isovector d 3/2 → d 5/2 M1 matrix element. The spectrum of negative parity, T = 1 states is understood in terms of the weakcoupling model while that of the T = 0 states is comprised of octupole-quadrupole phonon multiplets. Positive-parity states from outside the s-d configuration are first observed between 9.5 and 10.5 MeV excitation energy.

Abstract. The 2*Si level scheme up to 14.5 MeV excitation energy is reevaluated using information from two preceding papers. It consists of approximately 250 levels which are almost completely characterized according to the quantum numbers 1, re, T of the levels. The properties of positive-parity states are compared to the predictions of shell model calculations within the complete s-d basis space using the unified s-d shell Hamiltonian. A spectrum of 48 experimental T = 1 states between 9.3 and 16 MeV is reproduced with a rms deviation of only 150 keV. A calculation of radiative widths and 7-decay modes which uses free-nucleon 9-factors yields excellent agreement with experiment and confirms that quenching of M1 transitions is only marginal in 2ssi. The detailed shell model analysis of the T = 0 spectrum is extended to the limiting energy where T = 1 wave function admixtures, not contained in the theory, become important experimentally. This happens at 6-8 MeV above the yrast state, depending on the spin value. Altogether it appears that a spectrum of 171 levels below 14.5 MeV, which have positive or unassigned parity, is almost completely accounted for by the model. Apparent intruder states from outside the s-d shell space are observed at Ex=lO945keV (U=4 +) and 12860 keV (U= 6 +) and are interpreted as members of a K S = 0 + rotational band.

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