Measurement of Quadrupole-Dipole Mixing Amplitudes of Gamma Transitions Between Collective States of Even-Even Nuclei Using the Angular Correlation Method
Abstract
Gamma-gamma directional correlation measurements have been performed in order to test the predictions of various nuclear models regarding the multipole mixing ratios of gamma transitions from collective levels in even-even nuclei.High-resolution Ge (Li) detectors were used in conjunction withmultichannel gating and routing techniques to measure the directional correlations and to make corrections for chance coincidences and for Compton background effects. The multipole mixing ratios were determined in terms of explicitly defined reduced electromagnetic matrix elements, and were determined for collective vibrational, rotational, and transitional even-even nuclei; the measured values were then compared with the appropriate theoretical predictions as a test of the validityof the particular model in question.Results of the measurement, given in terms of the nucleus under investigation and the energy (in keV) of the mixed-multipole gamma transition, were: 110 Cd - 8(447) = - 0.45 plus/minus 0.2 , 8(620) = - 0.8 plus/minus 0.5 8(678) = - 0.25 plus/minus 0.2 5(687) =-1.1 -0.4 +0.8 , 8(707) = - 1 plus/minus 0.3 8(818) = - 1.2 plus/minus 0.15 , 8(1384) = - 0.37 plus/minus 0.03 8(1505) = - 0.55 plus/minus 0.1 124Te - 8(722) = - 3.7 plus/minus 0.3 160 Dy - 8(215) = - 0.18 plus/minus 0.1 , 8(299) =0.005 0.010, 8(392) = 0.01 0.06, 8(879) 8(962) = -18.05.0, 8(1176) = 0.02 ± 0.02, (1272) -13.5 3.0, -0.03 0.03; = 18608 +3 =-10-10 5(773) 19008 Ов - 8(630) 8(635) -6.9 ± 3.2; 194 pt 5(294) +4 188 -12_8; Os - - 8(478) = -12.3 ± 2.8, B(371) -8.5 1.0, 5(569) = -9.0 ± 1.5; = 14.3 ± 2.1: 196pt - 8(333) 6(333) -6.5 ± 0.3.110 The results obtained for the Cd gamma transitions indicated considerable deviations from the vibrational model. The results for 160, Dy were consistent with the rotational model, assuming band mixing in the negative parity states. The results for the mixing ratios in the osmium-platinum region were in excellent agreement with the predictions of the Kumar-Barenger pairing-plus-quadrupole model.
Degree
Ph.D.
Subject Area
Nuclear physics
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