| Popis: |
The (3He,d) reaction has been investigated at 25 MeV on the target nuclei 16O, 18O, 19F, 23Na, 24Mg, 25Mg, 26Mg, 27Al, 28Si, 29Si, 30Si, 31P, 32S, 34S, 35Cl, 37Cl and 39K. Attention is restricted to the few even-parity levels in each final nucleus which are strongly populated. Values of the single-nucleon Spectroscopic factors C2S are obtained from the differential cross sections measured for these levels by analyzing them in the framework of the DWBA theory of nuclear reactions. The DWBA calculations use sets of 3He and deuteron optical-potential parameters which are experimentally validated and internally consistent. The absolute values of C2S thus extracted are rather insensitive to which sets of equivalent optical-model parameters are used in the DWBA analyses (variations of the order of ±15%) and the variations in the relative values for the different transitions are very insensitive to these choices. Most of the sensitivity which does exist can be traced to the specification of the absorptive part of the deuteron potential. The values of C2S are not sensitive to the presence of spin-orbit terms in either the deuteron or the 3He potential. Contrary to the case for optical-model potentials, however, absolute values of C2S are very sensitive to the radius parameter r0 chosen for the potential which binds the transferred proton, although relative values are almost completely insensitive to this choice. The effects of the spin-orbit part of this bound-state potential on j = l + 1 2 and j = l − 1 2 transitions have also been carefully investigated. Evidence is developed that the radius parameter rs.o. of the spin-orbit part of the bound-state potential should be smaller than that of the central part. The values of C2S extracted from the present data both with standard DWBA analyses (r0 = rs.o. and a0 = as.o.) and with analyses which incorporate a modified treatment of the spin-orbit term of the bound-state potential (r0 ≠ rs.o. and a0 ≠ as.o.) are compared with the predictions of the USD shell-model hamiltonian. The ratios between the experimentally based spectroscopic factors and the model predictions exhibit a marked difference between transitions into the 1 d 3 2 orbit and transitions into the 1 d 5 2 orbit when the standard DWBA analysis is used. However, this difference between 1d 3 2 and 1d 5 2 transitions is greatly reduced if, while the conventional values r0 = 1.25 fm and a0= 0.65 fm continue to be used for the central component of the bound-state potential, values of rs.o. = 1.00 fm and as.o. = 0.52 fm are used for the spin-orbit part. |
