Magnetic dipole resonance in light nuclei

The ¿ decay of the resonance-like structures observed in the reaction of radiative capture of protons by the nuclei 21,22Ne, 25,26Mg, 29,30Si, 34,36S, 40¿r in the Ep = 0.8¿3.0 MeV range of accelerated protons was investigated. The magnetic dipole resonance (MDR) in 22,23Na, 26,27¿1, 30,31¿, 35,37Cl, 39K was identified. New experimental data were found on the occurrence of triplet coupling between an odd neutron and a proton in one orbit. This is reflected in the position of the center of gravity of the MDR of odd¿odd 4N + np nuclei, being 3 MeV lower in excitation energy than the center of gravity of the MDR in even¿even 4N nuclei and virtually independent of A. (It is common knowledge that the dependence should be ¿ = (35-45)¿¿1/3.) The difference in the position and total strength of the MDR in odd nuclei of sd-shells is attributed to the effect of pairing forces and transitions of valent nucleons.