INVESTIGATION OF THE $sup 24$Mg(/cap alpha/,$gamma$) $sup 28$Si REACTION AND OF SOME $sup 27$Al(p,$gamma$$)$$sup 28$Si RESONANCES
The yield of 8 to 13 Mev gamma radiation from the Mg ( alpha , gamma ) Si/sup 28/ reaction is measured in the E alpha = 1.2 to 3.2 Mev range, making use of natural Mg and enriched Mg/sup 24/ targets. Twenty resonances are observed corresponding to Size levels in the 11.3 to 12.8 Mev region. Six resonances show a relatively strong ground-state transition ( gamma /sub 0/); the spin and parity (either 1/sup -/, or 2/sup +/) of these resonances is uniquely determined through angular distribution measurements. At nine other resonances the angular distribution of gamma /sub 1/, the transition to the Si/sup 28/ first-excited state at 1.77 Mev, was measured; along with angular correlation measurements in several different geometries, this measurement uniquely determines the J/sup pi / of these resonances. The remaining five resonances are weak. The strongest resonances have J/sup pi / = 2/sup +/ or 4/sup +/. These are deexcited through E2 or strongly mixed M1-- E2 transitions. In both the Mg/sup 24/( alpha , gamma )Si/sup 28/ and Al/sup 27/(p, gamma ) Si/sup 28/ reactions a level in Si at 12.24 Mev is excited. The (unique) spin determinations from these reactions, however, do not agree, yielding J/sup pi / = 41 and J/sup pi / = 3/sup +/, respecti vely. Although the gamma -ray single spectra are closely analogous, pronounced differences exist in the gamma -- gamma coincidence spectra measured from the two reactions, showing that actually two closely spaced ( DELTA E approximately 0.6 kev) levels in Si/sup 28/ are excited. An extremely weak resonance in the Ai/sup 27/(p, gamma )Si/sup 28/ reaction is observed at E/sub p/ = 202.3 plus or minus 0.9 kev. The data obtained from the Mg/sup 24/( alpha , gamma )Si/sup 28/ reaction are compared with the information from the Al/sup 27/(p, gamma )Si/sup 28/ and Al/sup 27/(p, alpha )Mg/sup 24/ reacti ons. From the measured yields of these three reactions, the partial widths GAMMA /sub alpha /, GAMMA /sub p/, and GAMMA /sub gamma / are computed for most resonanc e levels. (auth)
- Research Organization:
- Rijksuniversiteit, Utrecht
- NSA Number:
- NSA-17-007262
- OSTI ID:
- 4758553
- Journal Information:
- Physica, Journal Name: Physica Vol. Vol: 28
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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