M. Palarczyk et al., CROSS-SECTIONS AND ANALYZING POWERS FOR THE ((P)OVER-RIGHT-ARROW,N) REACTION ON HE-3 AND HE-4 AT 200 MEV, Physical review. C. Nuclear physics, 58(2), 1998, pp. 645-657
Double-differential cross sections and analyzing powers A, for the ((p
) over right arrow,n) reactions on He-3 and He-4 were measured at 200
MeV between (0)lab= 0 degrees and 44 degrees. The neutron spectra from
He-3((p) over right arrow,n) are dominated by the quasifree scatterin
g peak and show no evidence for resonances in the three-proton system.
The spectra from He-4((p) over right arrow,n) exhibit strong resonanc
e behavior in the p(3)He system at low relative p3He energies owing to
the excitation of known L=1 resonances in Li-4, but there is no disti
nct quasifree peak in the measured spectra. The experimental A, for He
-3((p) over right arrow,n,n), averaged over the experimental range of
neutron energies, are similar to those for free nucleon-nucleon (NN) s
cattering, whereas for He-4((p) over right arrow,n) the A(y) are gener
ally larger than the free values, The cross sections at far forward an
gles for both He-3 and He-4 appear to be suppressed relative to the fr
ee NN cross sections by Pauli blocking. At most angles, the shapes of
the cross section spectra from both He-3 and He-4 are reproduced by di
storted-wave impulse approximation (DWIA) calculations using a quasifr
ee scattering model. Specifically for He-4((p) over right arrow,n), th
e model requires the use of an optical potential which has a strong L=
1 potential resonance corresponding to the low-lying L=1 states in Li-
4.