24 research outputs found
Study of nuclear correlation effects via 12C(p,n)12N(g.s.,1+) at 296 MeV
We report measurements of the cross section and a complete set of
polarization observables for the Gamow--Teller reaction at a bombarding
energy of 296 MeV.
The data are compared with distorted wave impulse approximation calculations
employing transition form factors normalized to reproduce the observed
beta-decay value.
The cross section is significantly under-predicted by the calculations at
momentum transfers 0.5 .
The discrepancy is partly resolved by considering the non-locality of the
nuclear mean field. However, the calculations still under-predict the cross
section at large momentum transfers of 1.6 .
We also performed calculations employing random phase approximation response
functions and found that the observed enhancement can be attributed in part to
pionic correlations in nuclei.Comment: 5 figures, submitted to Phys. Lett.
1,3-Dimesitylimidazolidinium tetrachloridogold(III) dichloromethane solvate
The title ionic compound, (C21H27N2)[AuCl4]·CH2Cl2, was obtained from the reaction of 1,3-dimesitylimidazolidinium chloride with t-BuOK and a solution of AuCl3 in tetrahydrofuran. In the crystal structure, numerous weak C—H⋯Cl hydrogen bonds form double layers parallel to (100), which are further stabilized by π–π interactions between mesitylene rings [centroid–centroid distance = 4.308 (4) Å], resulting in the formation of a three-dimensional supramolecular assembly
Performance of the neutron polarimeter NPOL3 for high resolution measurements
We describe the neutron polarimeter NPOL3 for the measurement of polarization
transfer observables with a typical high resolution of 300 keV
at 200 MeV.
The NPOL3 system consists of three planes of neutron detectors.
The first two planes for neutron polarization analysis are made of 20 sets of
one-dimensional position-sensitive plastic scintillation counters with a size
of 100 cm 10 cm 5 cm, and they cover the area of 100
100 .
The last plane for detecting doubly scattered neutrons or recoiled protons is
made of the two-dimensional position-sensitive liquid scintillation counter
with a size of 100 cm 100 cm 10 cm.
The effective analyzing powers and double scattering
efficiencies were measured by using the three kinds
of polarized neutrons from the , , and reactions at = 198 MeV.
The performance of NPOL3 defined as
are similar to that of the
Indiana Neutron POLarimeter (INPOL) by taking into account for the counter
configuration difference between these two neutron polarimeters.Comment: 28 pages, 18 figures, submitted to Nucl. Instrum. Methods Phys. Res.
Isovector effective NN interaction in 28Si(p,n)28P(6-) at 198 MeV
We report measurements of the cross section and a complete set of polarization observables for the View the MathML source reaction at a bombarding energy of 198 MeV. The data are compared with distorted wave impulse approximation calculations employing response functions normalized to inelastic electron scattering. The spin-longitudinal polarized cross section IDq is slightly over-predicted by the calculations, while the normal spin-transverse polarized cross section IDn is significantly under-predicted. The calculated in-plane spin-transverse IDp and spin-scalar ID0 polarized cross sections agree well with the experimental data. These results are consistent with those for View the MathML source scattering at the same energy, and thus it is concluded that isospin-mixing effects are not responsible for the discrepancy between theory and experiment in the View the MathML source case. Energy half-off-shell effects as medium effects on the effective nucleon?nucleon interaction are also investigated and found to be too small to be responsible for the discrepancy
Polarization transfer measurements for at 296 MeV and nuclear correlation effects
Differential cross sections and complete sets of polarization observables are
presented for the Gamow-Teller reaction at a bombarding energy of 296 MeV with momentum transfers
of 0.1 to . The polarization transfer observables are
used to deduce the spin-longitudinal cross section, , and spin-transverse
cross sections, and . The data are compared with calculations
based on the distorted wave impulse approximation (DWIA) using shell-model wave
functions. Significant differences between the experimental and theoretical
results are observed for all three spin-dependent at momentum transfers
of , suggesting the existence of nuclear
correlations beyond the shell model. We also performed DWIA calculations
employing random phase approximation (RPA) response functions and found that
the observed discrepancy is partly resolved by the pionic and rho-mesonic
correlation effects.Comment: accepted for publication in Phys. Rev.