A study of 0° transverse polarization transfer in (p, n) reactions from 12C,13C and 40Ca at 80 and 50 MeV

doi:10.1016/0375-9474(94)90792-7

Nuclear Physics A

Volume 579, Issues 1–2, 17 October 1994, Pages 45-61

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Abstract

Transverse-polarization-transfer coefficients D_NN for the (p, n) reaction at θ = 0° have been measured on ¹²C,¹³C and ⁴⁰Ca targets at E_p = 80MeV and the ¹²C and ¹³C targets at E_p = 50MeV. As for the ¹²C and ¹³C (p, n) reactions, D_NN for the transitions corresponding to the Gamow-Teller type and the Fermi and Gamow-Teller mixed type are compared to distorted-wave Born-approximation calculations. Observed D_NN values are reproduced reasonably well by the calculations employing either the effective interactions M3Y or the M3Ym in which V_TτandV_στ are modified. A value for R² = [σ_GT(0°)/σ_F(0°)][B(F)/B(GT)] is deduced by using only the D_NN data from the ¹³C (p, n) reaction, and is roughly consistent with R = 1/55 E_p, empirically determined from the cross-section data at 0°. As for the ⁴⁰Ca(p, n) reaction, the observed value for the giant-dipole-resonance region is D_NN = 0.23±0.05, indicating that the spinflip and non-spinflip resonances are unresolved. Utilizing information from higher-energy D_NN data, the transition-strength ratio f of non-spinflip to spinflip and D_NN(SF) pertinent to spinfli[ transitions have been deduced empirically for the giant-dipole-resonance region. Obtained f and D_NN(SF) values are 1.4±0.4 and −0.25±0.10, respectively, and are roughly consistent with the RPA calculations.

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Cited by (7)

Energy levels of light nuclei A = 12
2017, Nuclear Physics A
Nuclear Data Sheets for A=40
2017, Nuclear Data Sheets
The experimental nuclear structure data and decay data are evaluated for the known nuclides of mass 40 (Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti). Detailed evaluated nuclear structure information is presented with the best values recommended for level energies, half-lives, γ-ray energies and intensities, decay properties (energies, intensities and placement of radiations), and other spectroscopic data. The ⁴⁰Ca and ⁴⁰K nuclides remain as the most extensively studied from many different reactions and decays; no excited states are known in ⁴⁰Mg, ⁴⁰Al, ⁴⁰P and ⁴⁰Ti. This work supersedes the earlier full evaluation of A=40 by J. Cameron and B. Singh (2004Ca38).
Nuclear data sheets for A = 40
2004, Nuclear Data Sheets
Nuclear spectroscopic information for the known nuclides of mass 40 (Al,Si,P,S,Cl,Ar,K,Ca,Sc,Ti) has been evaluated. The principal sources of the adopted levels presented are Endt's evaluations (1990En08, 1978En02). The data sets for reactions and decays, including all available gamma-ray data, are based mostly on the original literature. There are no data available for the excited states in ⁴⁰Al, ⁴⁰Si, ⁴⁰P and ⁴⁰Ti. The identification and particle stability of ⁴⁰Mg are still uncertain, although search for this nuclide has been made (2002Lu09,2002No11,2003Pe31).
On the conversion of charge-exchange cross sections to "GT" strength: Anomalies in odd-A nuclei
2001, Nuclear Physics A
Facility for the (p, n) polarization transfer measurement
1996, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
We have designed and constructed a facility to measure the complete polarization transfer coefficient D_ij for the (p, n) reaction at intermediate energies. The facility consists of a beam swinger dipole magnet used for angular distribution measurements and a 100 m tunnel for the neutron energy measurement by the time-of-flight method. Typical neutron energy resolution is about 1.85 MeV for 290 MeV neutrons including a contribution of 1 MeV due to the target thickness. The background associated with this tunnel system was carefully investigated and found to be negligibly small. A dipole magnet for the neutron spin rotation is installed in the neutron flight path to measure the longitudinal polarization as well as the induced polarization. The neutron polarimeter which consists of 6 planes of the two-dimensional position-sensitive neutron detectors with a size of 1 m × 1 m × 0.1 m has been constructed. Its effective left-right analyzing power 〈A_y^eff〉 has been calibrated at 194, 290 and 384 MeV. The figure-of-merit value defined by 〈A_y^eff〉² × ε_DS at 290 MeV is 4.05 × 10⁻⁴, where ε_DS is the double scattering efficiency.
Spin-flip probability via the 26Mg(3He,tγ)26Al reaction
1995, Nuclear Physics, Section A
The spin-flip probability for the charge-exchange reaction ²⁶Mg(³He,tγ)²⁶Al (1⁺; 1.06 MeV) has been measured at E = 53 MeV and θ_lab = 10°. The extracted value is 0.41 ± 0.04. A microscopic DWBA calculation with empirically determined effective interactions reproduces the observed cross sections fairly well but the spin-flip probability poorly. To supplement the (³He,tγ) study, the spin-flip probability has been measured for the same state by the charge-exchange (p,nγ) reaction at 35 MeV and θ_lab = 30° and found to be 0.52 ± 0.11. Though statistically not significant the lower value of S in the (³He,t) reaction may reflect on the more complex nature of this reaction at the present bombarding energy.

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Nuclear Physics A

Abstract

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Cited by (7)

Energy levels of light nuclei A = 12

Nuclear Data Sheets for A=40

Nuclear data sheets for A = 40

On the conversion of charge-exchange cross sections to "GT" strength: Anomalies in odd-A nuclei

Facility for the (p, n) polarization transfer measurement

Spin-flip probability via the <sup>26</sup>Mg(<sup>3</sup>He,tγ)<sup>26</sup>Al reaction