J. Vernotte et al., SPECTROSCOPIC FACTORS FROM ONE-PROTON STRIPPING REACTIONS ON SD-SHELLNUCLEI - EXPERIMENTAL MEASUREMENTS AND SHELL-MODEL CALCULATIONS, Nuclear physics. A, 571(1), 1994, pp. 1-42
The (He-3,d) reaction has been investigated at 25 MeV on the target nu
clei O-16, O-18, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29
, Si-30, P-31, S-32, S-34, Cl-35, Cl-37 and K-39. Attention is restric
ted to the few even-parity levels in each final nucleus which are stro
ngly 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 nuclea
r reactions. The DWBA calculations use sets of He-3 and deuteron optic
al-potential parameters which are experimentally validated and interna
lly consistent. The absolute values of C2S thus extracted are rather i
nsensitive to which sets of equivalent optical-model parameters are us
ed in the DWBA analyses (variations of the order of +/-15%) and the va
riations in the relative values for the different transitions are very
insensitive to these choices. Most of the sensitivity which does exis
t can be traced to the specification of the absorptive part of the deu
teron potential. The values of C2S are not sensitive to the presence o
f spin-orbit terms in either the deuteron or the He-3 potential. Contr
ary to the case for optical-model potentials, however, absolute values
of C2S are very sensitive to the radius parameter r0 chosen for the p
otential which binds the transferred proton, although relative values
are almost completely insensitive to this choice. The effects of the s
pin-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 d
eveloped that the radius parameter rs.0 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 = r(s.o.) and a0 = a(s.o)) and with analyses which i
ncorporate a modified treatment of the spin-orbit term of the bound-st
ate potential (r0 not-equal r(s.o.) and a0 not-equal a(s.o.)) are comp
ared with the predictions of the USD shell-model hamiltonian. The rati
os between the experimentally based spectroscopic factors and the mode
l predictions exhibit a marked difference between transitions into the
1d3/2 orbit and transitions into the 1d5/2 orbit when the standard DW
BA analysis is used. However, this difference between 1d3/2 and 1d5/2
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 r(s.o) = 1.00 fm and a(s.o) =
0.52 fm are used for the-spin-orbit part.