W. McLatchie

A Heavy Water Detector to Resolve the Solar Neutrino Problem

Abstract The observation of the following three reactions: νed→ppe; νxe→νxe; and νxd→νxpn (where νx is any left- handed neutrino) in a heavy water Cerenkov detector which is being designed, allows the solar 8B ve flux, spectrum and direction to be measured. In addition, the total solar 8 Bν c neutrino flux, direction and integral spectrum, independent of neutrino flavor, may be determined to provide several independent methods to resolve the solar neutrino problem.

The level structures of 85, 87Sr from (d, p) reactions

Abstract The reactions 84 Sr(d, p) 85 Sr and 86 Sr(d, p) 87 Sr have been studied at a bombarding energy of 12 MeV. Thirty-four levels below 4.5 MeV of excitation have been identified in 87 Sr and fifty-four levels below 3.5 MeV have been identified in 85 Sr. Transferred orbital angular momenta and spectroscopic information have been deduced from a DWBA analysis of the proton differential cross sections. It has been found that the lowest-lying excited states arise from 1g 9 2 , 2p 1 2 and 2p 3 2 configurations. The 1f 5 2 shell appears to be completely filled in these low-mass strontium isotopes.

Effective interaction among 1g92 and 2p12 neutrons in the strontium isotopes

Abstract In the seniority scheme an effective interaction shell-model calculation has been carried out for the low-lying structure of the strontium istopes. The model predictions are compared with existing experimental data and the quality of the seniority quantum number evaluated. Differences between effective neutron matrix elements have been determined and compared with the corresponding proton case. Comparisons of predicted two-neutron transfer cross sections with experimental data have been used to remove ambiguities in the sign of certain off-diagonal matrix elements.

12C( alpha, gamma )16O cross sections at stellar energies.

The excitation function of the C12(α,γ)16O reaction and the angular distribution of its γ rays were measured at nine center-of-mass energies ranging from E=1.37 to 2.98 MeV. These measurements allowed the separation of the E1 and E2 contributions and their extrapolation to the region of astrophysical interest. The analysis of all the available E1 cross sections with the K-matrix method and with a three-level R-matrix method yields a consistent prediction of 79±16 keV b for the E1 S factor at 300 keV. The E2 contribution at the same energy is 36±6 keV b from a cluster model analysis of the present data. The best estimate of the total S factor at 300 keV is 120 keV b, and it is unlikely that it will fall outside the range of 80–160 keV b.

EFFECTIVE INTERACTION AMONG 1g/sub 9/2/ AND 2p/sub 1/2/ NEUTRONS IN THE STRONTIUM ISOTOPES.

Abstract In the seniority scheme an effective interaction shell-model calculation has been carried out for the low-lying structure of the strontium istopes. The model predictions are compared with existing experimental data and the quality of the seniority quantum number evaluated. Differences between effective neutron matrix elements have been determined and compared with the corresponding proton case. Comparisons of predicted two-neutron transfer cross sections with experimental data have been used to remove ambiguities in the sign of certain off-diagonal matrix elements.

Analogue states in 61Cu

Abstract Resonances in the reaction 60Ni(p, γ)61Cu have been studied in the energy region Ep ≈ 1550–1950 keV. Decay schemes and branching ratios are presented for 12 resonances and the resonance strength has been determined for most of these. Gamma-ray angular distribution measurements on two resonances yield the following spin assignments (E p ( keV ; J): (1668; 5 2 ), (1850; 3 2 , 5 2 ) . Several of the resonances studied are identified as fragments of the analogue states of the ground and first two excited states in 61Ni. M1 transitions strengths to the corresponding antianalogue candidates have been measured.

The conservation of seniority in the 1g92 neutron shell

Abstract The results of one- and two-neutron transfer reactions across the strontium isotopes are applied to a study of the conservation of seniority in the 1 g 9 2 neutron shell.

Electromagnetic properties of the ground state rotational band in 169Tm

Abstract Beams of 32S ions at energies up to 140 MeV have been used to excite the ground state band of 169Tm (Kπ = 1 2 +) as high as its spin 23 2 member by multiple Coulomb excitation. Lifetimes for levels from spin 9 2 to spin 21 2 have been determined by the recoil distance and Doppler broadened lineshape methods. Branching and multipole mixing ratios were deduced from the measured γ-ray angular correlations. From these data it has been possible to extract, without reference to the rotational model, many of the B(E2) and B(M1) values connecting the band members. The agreement with the rotational model is exceptionally good for all the measured quantities. The inclusion of a K = 3 2 mixing into the ground state band improves the fit to the energies to the detriment of the fit to the B(M1) values at high spin.

The γ-ray decay properties of analogue states of 55Fe excited in the reaction 54Fe(p, γ)55Co

Gamma-ray angular distribution, polarization and resonance strength measurements have been carried out on resonances observed in the reaction 54Fe(p, γ)55Co at proton energies of 1803 and 1887 keV. These resonances at excitation energies of 6833 and 6916 keV in 55Co have Jπ = (32−) and 52− and resonance strengths of (2J + 1) ΓγΓpΓ = 0.98 and 0.45 eV respectively. These resonance states have been identified as analogues of the 2050 keV (Jπ = 32−) and 2144 keV (52−) states in 55Fe. A state at 4722 keV (32−) has been identified as the analogue of the ground state of 55Fe. Transition probabilities for γ-rays de-exciting these analogue states are examined. Although no strong analogue-antianalogue transitions from the resonance levels are observed there are strong transitions between the analogue states and also from the analogue of the 55Fe ground state to a T = 12 state in 55Co.

Electric quadrupole moments of the first excited states of 28Si, 32S and 34S

Abstract The reorientation effect in Coulomb excitation has been used to measure the following static electric quadrupolemoments: Q 2 + ( 28 Si ) = +17.5 ± 2.9 e · fm 2 , Q 2 ( 32 S) = −11.5 ± 4.8e · fm 2 and Q 2 + +( 34 S) = +6.3 ± 4.3 e · fm 2 . Energy spectra from the 208 Pb+ 28 Si, 32, 34 S reactions at E = 105–122 MeV were obtained with the Chalk River Q3D spectrometer. These data were fitted with accurate B ( E 2; 0 + → 2 + ) values determined from a weighted average of all previous measurements combined with those measured by the Doppler shift attenuation method by using the inverse reactions 4 He( 32, 34 S, α) where the mean 2 + 1 state lifetimes were found to be 0.236 ± 0.016 ps ( 32 S) and 0.442 ± 0.026 ps( 34 S).