1,382 research outputs found
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.
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.
Two-step contribution to the spin-longitudinal and spin-transverse cross sections of the quasielastic (p,n) reactions
The two-step contribution to the spin-longitudinal and the spin-transverse
cross sections of ^{12}C,^{40}Ca(p,n) reactions at 494 MeV and 346 MeV is
calculated. We use a plane-wave approximation and evaluate the relative
contributions from the one-step and the two-step processes. We found that the
ratios of the two-step to the one-step processes are larger in the
spin-transverse cross sections than in the spin-longitudinal ones. Combining
these results with the distorted-wave impulse approximation (DWIA) results we
obtained considerable two-step contributions to the spin-longitudinal and the
spin-transverse cross sections. The two-step processes are important in
accounting for the underestimation of the DWIA results for the
spin-longitudinal and the spin-transverse cross sections.Comment: LaTeX 11 pages, 10 figure
Expression of unprocessed glutelin precursor alters polymerization without affecting trafficking and accumulation
Rice glutelin is synthesized as a precursor in the endosperm endoplasmic reticulum and then deposited within the protein storage vacuole protein body-II (PB-II) as an aggregate, with a high degree of polymerized higher-order structure comprising mature acidic and basic subunits after post-translation processing cleavage. In order to investigate the functional role of this processing and its effect on folding assembly, wild-type GluA2 and its mutant cDNA (mGluA2), in which the conserved processing site (Asn-Gly) at the junction between the acidic and basic chains was replaced with Ala-Ala, were expressed under the control of the endosperm-specific GluB1 promoter in the mutant rice a123 line lacking glutelin GluA1, GluA2, and GluB4. The mGluA2 precursor was synthesized and stably targeted to PB-II without processing in the transgenic rice seeds like the wild-type GluA2. Notably, the saline-soluble mGluA2 precursor assembled with the other type of processed glutelin GluB as a trimer in PB-II, although such hetero-assembly with GluB was not detected in the transformant containing the processed GluA. Furthermore, the mGluA2 precursor in the glutelin fraction was deposited in PB-II by forming a quite different complex from the processed mature GluA2 products. These results indicate that post-translational processing of glutelin is not necessary for trafficking and stable accumulation in PB-II, but is required for the formation of the higher-order structure required for stacking in PB-II
Complete set of polarization transfer coefficients for the reaction at 346 MeV and 0 degrees
We report measurements of the cross-section and a complete set of
polarization transfer coefficients for the reaction at a
bombarding energy = 346 MeV and a reaction angle =
.
The data are compared with the corresponding free nucleon-nucleon values on
the basis of the predominance of quasi-elastic scattering processes.
Significant discrepancies have been observed in the polarization transfer
, which are presumably the result of the three-proton =
3/2 resonance.
The spin--parity of the resonance is estimated to be , and the
distribution is consistent with previous results obtained for the same reaction
at = 48.8 MeV.Comment: 4 figures, Accepted for publication in Physical Review
Determination of the Gamow-Teller Quenching Factor from Charge Exchange Reactions on 90Zr
Double differential cross sections between 0-12 degrees were measured for the
90Zr(n,p) reaction at 293 MeV over a wide excitation energy range of 0-70 MeV.
A multipole decomposition technique was applied to the present data as well as
the previously obtained 90Zr(p,n) data to extract the Gamow-Teller (GT)
component from the continuum. The GT quenching factor Q was derived by using
the obtained total GT strengths. The result is Q=0.88+/-0.06 not including an
overall normalization uncertainty in the GT unit cross section of 16%.Comment: 11 papes, 4 figures, submitted to Physics Letters B (accepted),
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Measurement of Single and Double Spin-Flip Probabilities in Inelastic Deuteron Scattering on 12C at 270 MeV
The deuteron single and double spin-flip probabilities, S1 and S2, have been
measured for the 12C(pol{d},pol{d}') reaction at Ed = 270 MeV for an excitation
energy range between 4 and 24 MeV and a scattering angular range between
Theta_lab = 2.5 and 7.5 deg. The extracted S1 exhibits characteristic values
depending on the structure of the excited state. The S2 is close to zero over
the measured excitation energy range. The SFP angular distribution data for the
2+ (4.44 MeV) and 1+ (12.71 MeV) states are well described by the microscopic
DWIA calculations
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
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