L. Eriksson

Levels in 115In populated in the decay of 115mCd

Abstract The decay of 115mCd to 115In is studied. Gamma intensities are measured with a Ge(Li) detector. Two new transitions are observed and placed in the level scheme. The following γ-γ directional correlations are determined (energies in keV): 484.35–933.6, 158.1–1132.5 and 316.1–1132.5. The M1 strengths are derived for two transitions connecting members of the vibrational multiplet: B( M 1, 1290.5 13 2 + → 1132.5 11 2 + ) = 0.5 ± 0.1 μ 2 0 and B( M 1, 1448.7 9 2 + 1132.5 11 2 + ) = 0.5 ± 0.3 μ 2 0 . The half-life of the 933.6 7 2 + state as measured by the delayed-coincidence technique is T 1 2 = 57 ± 5 ps . The partial half-life of the 933.6 7 2 + → 828.4 3 2 + E2 transition is 55 times less than the Weisskopf estimate. The static quadrupole moment of the 7 2 + and 3 2 + states is evaluated on the assumption that these levels are members of the proposed rotational band: Q0 = 2.7 ± 0.3 b. This is in agreement with the corresponding value for the 864.0 1 2 + → 828.4 3 2 + transition, and the result of a recent direct measurement of the static quadrupole moment of the 828.4 3 2 + state. The suggestion that the 1418.0 9 2 + level is also deformed is supported by the fact that the decay occurs preferentially to the 933.6 7 2 + state, whereas no transition connecting the 1448.7 9 2 + state with the 933.6 7 2 + state is observed.

Gamma-gamma Directional Correlations in 103Rh

Gamma-gamma directional correlations in 103Rh were measured in the decay of 103Ru. No dependence on the chemical composition of the source was observed. The following directional correlation coefficients were determined: A2(557 - 53) = -0.064 ± 0.003, A2(444 - 53) = -0.035 ± 0.013. The lifetime of the 93 keV state was measured as T½ = 1.06 ± 0.05 ns. By use of this value for the lifetime and the rotation in an external magnetic field of the directional correlation pattern, the gyromagnetic factor of the 93 keV state is obtained as g = 1.07 ± 0.17. The properties of 103Rh were calculated on basis of the unified vibrational model. The adequacy of this model for describing the positive-parity states studied in this work is discussed.

Mixing ratios in67Zn determined by gamma-gamma angular correlations

The gamma-gamma angular correlations of the 209.0–184.6, 494.3–393.6, 494.3–300.2 and 703.6–184.6 keV cascades in67Zn have been measured. Mixing ratios of the 209.0, 300.2, 393.6 and 703.6 keV transitions are deduced. A spectroscopic study could not confirm the existence of a recently proposed level at 710 keV.

Levels and transitions in136Ba

Excited states of136Ba are studied in the beta decay of136Cs. The gamma spectrum is measured with high-resolution and coincidence techniques. Several new transitions are suggested to be connected with two recently reported levels. Gamma-gamma directional correlations are performed in an attempt to determine the characteristics of these levels, and in order to determine mixing ratios. The lifetime of the 2207.5 keV state is remeasured, and the lifetime of the 2140.5 keV state is measured for the first time.

Levels and transitions in126Te

The decay of126Sb to126Te is studied by use of Ge(Li) detectors in singles and coincidence arrangements. The gamma-gamma directional correlations of six cascades are measured. A level scheme is constructed where all transitions observed are located. The characteristics of several of the levels are assigned, on basis of the logft values deduced and the directional correlation results. Mixing ratios are deduced for three transitions. From the comparison of the relative intensities ofE1 andE2 transitions depopulating the same levels, threeE1 transitions are concluded to be strongly retarded.

Angular Correlation Studies in 207Pb

By use of a 56-channel goniometer, gamma-gamma angular correlations have been measured in 207Pb. The following mixing ratios were derived: δ(1 770γ) = 0.085 (2), δ(897γ) = 0.11 (6) and δ(1 064γ) = 0.031 (6). The consequences of these data on the transition probabilities are discussed.

The g-factor of the 1 291.5 keV State in 59Co

The g-factor of the 1 291.5 keV state in 59Co has been determined by the IPAC method. A multichannel goniometer was used in the study of the perturbed angular correlation of the 142.5-1 291.5 keV cascade. Four sources were used, 59Fe:Fe, 59Fe:Co, 59Fe:Ni and 59Fe:Cu. The g-factor was found to be 1.69 (8) based on an analysis of the iron, nickel and copper data. The corresponding magnetic moment, μ = 2.54 (12)μN, is compared with the prediction of a unified vibrational model. Neglecting the static electric quadrupole interaction between the 59Co nucleus and its environment in cobalt metal, the magnetic hyperfine field experienced by 59Co in cobalt was found to be -217 (22) kG at room temperature.

Mixing Ratios in 59Co Determined by Gamma-gamma Angular Correlations

The E2/M1 mixing ratios of the 142.5, 192.2 and 334.7 keV transitions in 59Co are determined with the gamma-gamma angular correlation technique, by use of a 56-channel goniometer. The results are δ142.5 = -0.006 (12), δ192.2 = 0.21(2) and δ334.7 = -0.12(4). The mixing ratios and the associated E2 and M1 transition probabilities are compared with the predictions from a unified vibrational model. An upper limit of 0.9 per cent is found for the M3 admixture in the 1 291.5 keV transition.

The g-Factor of the 80.1 keV Level in 144Pr

The g-factor of the 80.1 keV level in 144Pr has been determined in an IPAC study of the 53.4-80.1 keV cascade. With an external magnetic field of 21.7(3) kG the precession angle ωτ was measured to be -0.045(12). The result g = -1.2(4) agrees well with that calculated in terms of coupling of the effective moments of the odd particles, g = -1.43(7). From the directional correlation of the 53.4-80.1 keV cascade the mixing ratio of the 53.4 keV transition was determined, δ(E2/M1) = 0.043(3).