A. Robertson

Further experimental evidence for collective effects in 40Ca

Abstract Measurements of lifetimes, spins and decay modes of levels in 40 Ca excited by inelastic proton scattering have been made. The lifetimes were measured using the Doppler shift attenuation technique in a proton-gamma ray coincidence arrangement. The “level” at 6.03 MeV was found to be a doublet, with energies 6.026 MeV and 6.030 MeV. Proton-gamma ray angular correlation measurements, in conjunction with the lifetime results, showed the spins to be 2 − and (3 + , 2 − ) respectively. Similar measurements on the levels at 6.51 MeV and 6.54 MeV showed them both to be 4 + . The results of the lifetime measurements are as follows, 5.61 MeV (4 − ), 950 −190 +280 fsec: 5.63 MeV (2 + ), 76±21 fsec: 5.90 MeV(1 − ), 60±20 fsec: 6.026 MeV (2 − ), 260±30 fsec: 6.030 MeV (3 + , 2 − ), 560±190 fsec: 6.51 MeV(4 + ), 160±60 fsec: 6.54 MeV(4 + ), 190±60 fsec: 6.58 MeV (3 − ), 250±70 fsec. Mixing ratios are also reported: in particular the E2/M1 mixing ratio for the transition between the 2 + states at 5.25 MeV and 3.90 MeV was found to be −13 −6 +3 . Levels are identified with the rotational states predicted by Gerace and Green, and the measured E2 matrix elements, some of which are strongly enhanced, are found to be consistent with the model.

The spin, parity and lifetime of the 4.46 MeV state of 32S

Abstract The 4.46 MeV level in 32 S is found to have J π = 4 + and a lifetime of 0.13 ± 0.03 ps. The B(E2) extracted from this lifetime is compared with predictions of rotational and vibrational models.

An investigation of the low-lying states of 58Cu by the 58Ni(p, nγ)58Cu reaction

The γ-ray decay modes of the excited states of 58Cu below 1.7 MeV have been investigated by neutron-γ and γ-γ coincidence techniques following the 58Ni(p, nγ)58Cu reaction. Accurate excitation energies have been obtained for the 58Cu levels and the level at 1.65 MeV was found to be a doublet with energies 1.647 and 1.652 MeV. The Doppler-shift attenuation method has been used to measure the mean lifetimes of the following states: 1.052 MeV, 113 ± 1928 fsec; 1.428 MeV, > 960 fsec; 1.550 MeV, > 500 fsec; 1.647 MeV, > 1300 fsec; 1.652 MeV, 50 ± 10 fsec. The lifetime and decay mode of the 1.052 MeV level establishes its spin as J = 1 while the spin of the 0.445 MeV state has been restricted to J = 2 or 3 by a singles γ-ray angular distribution measurement. The results are compared to shell-model predictions calculated using Kuo-Brown two-body matrix elements.

Beta decay of 58Cu

Abstract The β + decay of the 1 + ground state of 58 Cu to excited states of 58 Ni has been investigated by a study of the subsequent de-excitation γ-rays using a Ge(Li) detector. Branching ratios for positon transitions to the following 58 Ni states were obtained: 1.454 MeV (2 + ), 2.0 ± 1.1 %; 2.775 MeV (2 + ), + ), 3.0 ± 1.2 %; 2.943 MeV (0 + ), 9.9 ± 1.6 %; 3.038 MeV (2 + ), 0.29 ± 0.09 %; 3.263 MeV (2 + ), 1.06 ± 0.14 %; 3.531 MeV (0 + ), + ), 0.67 ± 0.10 %; and 3.898 MeV (2 + ), 58 Ni and the log tf values deduced from the above branching ratios are compared to shell-model predictions.

BETA DECAY OF

Abstract The β + decay of the 1 + ground state of 58 Cu to excited states of 58 Ni has been investigated by a study of the subsequent de-excitation γ-rays using a Ge(Li) detector. Branching ratios for positon transitions to the following 58 Ni states were obtained: 1.454 MeV (2 + ), 2.0 ± 1.1 %; 2.775 MeV (2 + ), + ), 3.0 ± 1.2 %; 2.943 MeV (0 + ), 9.9 ± 1.6 %; 3.038 MeV (2 + ), 0.29 ± 0.09 %; 3.263 MeV (2 + ), 1.06 ± 0.14 %; 3.531 MeV (0 + ), + ), 0.67 ± 0.10 %; and 3.898 MeV (2 + ), 58 Ni and the log tf values deduced from the above branching ratios are compared to shell-model predictions.

sup 58

Abstract The β + decay of the 1 + ground state of 58 Cu to excited states of 58 Ni has been investigated by a study of the subsequent de-excitation γ-rays using a Ge(Li) detector. Branching ratios for positon transitions to the following 58 Ni states were obtained: 1.454 MeV (2 + ), 2.0 ± 1.1 %; 2.775 MeV (2 + ), + ), 3.0 ± 1.2 %; 2.943 MeV (0 + ), 9.9 ± 1.6 %; 3.038 MeV (2 + ), 0.29 ± 0.09 %; 3.263 MeV (2 + ), 1.06 ± 0.14 %; 3.531 MeV (0 + ), + ), 0.67 ± 0.10 %; and 3.898 MeV (2 + ), 58 Ni and the log tf values deduced from the above branching ratios are compared to shell-model predictions.