W.L. Mouton

Properties of low-lying levels of 45Sc

Abstract The spins and electromagnetic properties of levels up to 1800 keV in 45Sc were studied by means of inelastic proton scattering. Results are discussed with reference to the excited-core model.

Resonance strengths, branching ratios and mean lifetimes of nuclear energy levels in23Na

The gamma decay of the22Ne(p, y)23Na resonances in the proton energy rangeEp=1.0→2.0 MeV has been investigated with a 20cm3 Ge(Li) detector. Implanted targets were used. The absolute strengths of the strongest resonances were determined and the branching ratios of twenty resonance levels and several bound states are reported. Mean lifetimes of the levels atEx=2.078 MeV (18.7±3.5 fs), 2.393 MeV (580−190+370 fs), 2.641 MeV (88−14+20 fs), 2.985 MeV (4.0−1.0+1.3 fs), 3.679 MeV (24−4+5 fs), 3.915 MeV (7.4−2.0+2.5 fs) and 4.775 MeV (<2.0 fs) were obtained from measurements of the gamma ray Doppler shifts.

Lifetime measurements on 26Mg and 29Si by Doppler shift attenuation

Abstract The lifetimes of the lowest bound states of 26 Mg and 29 Si were determined by means of Doppler shift attenuation measurements. The results are τ m = 300 +100 −60 95±25, > 5000and 2100 +4000 −1000 fs for 26 Mg (1) through (4) and τ m = 560±130, 830±260 and 24±14 fs for 29 Si (1) through (3), respectively.

Level widths in 31P

Abstract Gamma rays of energy 8.201 MeV from the reaction 30 Si(p, γ ) 31 P at E p = 945 keV were resonantly absorbed in red phosphorus powder. The widths of the absorption curves obtained for three different absorber thickness were instrumental and determined primarily by the width of the absorber. The level parameters were calculated from the absorption integrals and an independent relative yield measurement. An attempt was also made to determine the level parameters from the variation of the absorption integral with absorber thickness. The following results were obtained: Γ t =2.6±0.2 eV , Γ γ0 =1.4±0.1 eV . The total width of the 7.90 MeV level at E p = 622 keV was also determined. Three different absorber thicknesses were used. The results obtained, viz. Γ t =68±9 eV , Γ γ0 =1.6±0.2 eV are in reasonable agreement with a previous measurement.

Resonant absorption of the γ-radiation from the22Ne(p, γ)23Na reaction and the effect of rutherford scattering in the target on the width of the absorption curves

Gamma rays of energy 9.404 and 9.700 MeV were obtained from the reaction22Ne(p, γ)23Na at proton energies of 640 and 950 keV respectively and were resonantly absorbed in sodium metal. Isotopically separated22Ne targets on nickel backings were used. The following level widths for23Na were obtained:The 9.404 MeV level: Γ=65 ±40eV Γγ=2.2±0.7eV.The 9.700 MeV level: Γ=9.5−1.0+4.5 eV Γγ=5.6−0.8+1.2 eV.The disagreement between the results for the 9.404 MeV level and the previously determined values can probably be ascribed to proton scattering in the window of the gas target used in the latter measurement.

Width of the 1.013 MeV level of 27Al

Abstract The width of the 3 2 + 1.013 MeV level of 27Al was determined in two nuclear resonant scattering experiments. In the first, the source of radiation was a 4000 Ci 60Co source. Gamma rays of the desired energy were obtained by Compton scattering of the 1.33 and 1.17 MeV photons through a precalculated angle. This radiation was then scattered from an Al scatterer and the resonantly scattered quanta observed at an angle of 120° with respect to the incident beam. In the second experiment, Doppler-broadened γ-rays emitted from the 27Al(p, p′γ) reaction were used to excite the 3 2 + state. The weighted mean value of the level width was found to be Λ = 1.3±0.4 MeV. This value is compared with various excited-core model calculations.

Gamma-rays from the24Mg(p,γ)25Al reaction for proton energiesEp=800 keV toEp=1,830 keV

The yield curve and resonance strengths of resonances in the24Mg(p, γ)25Al reaction for the proton energy rangeEp=800 keV toEp=1,830 keV, have been determined and the existence of a resonance atEp=1.184 MeV confirmed. Single energy spectra as well as decay schemes and branching ratios are given for these resonances. An upper level of 2.0×10−15 sec for the lifetime of the 3.079 MeV level in25Al results from a Doppler shift attenuation measurement carried out on the 2.624 MeV gamma line originating in the 3.070 MeV→0.455 MeV transition in25Al.

GAMMA RAYS FROM THE

The yield curve and resonance strengths of resonances in the24Mg(p, γ)25Al reaction for the proton energy rangeEp=800 keV toEp=1,830 keV, have been determined and the existence of a resonance atEp=1.184 MeV confirmed. Single energy spectra as well as decay schemes and branching ratios are given for these resonances. An upper level of 2.0×10−15 sec for the lifetime of the 3.079 MeV level in25Al results from a Doppler shift attenuation measurement carried out on the 2.624 MeV gamma line originating in the 3.070 MeV→0.455 MeV transition in25Al.