Kazusuke Sugiyama

Structure of platinum nuclei (I) new decay scheme of Au196

Abstract Nuclear structure of Pt 196 has been investigated from the decay of the 6.2 d Au 196 . New weak gamma rays of 312, 444, 522, 568, 644, 757, 762 and 1090 keV were found in the analysis of conversion electron spectra by the use of a sector-type double focusing beta ray spectrometer. These new gamma rays were all coincident with the 356 keV gamma transition between the first and ground state of Pt 196 . From the ratio of electron capture to positon emission rate ϵ K.L.M. / β + = 2.0±0.4 × 10 6 , the electron capture decay energy of the 6.2 d Au 196 is estimated as 1480 −12 +8 keV. Directional correlation measurements of 1090-356, 760-340, 530-340 and 333-356 keV gamma ray cascades were also performed. The level scheme of Pt 196 is proposed as folows: 1446 keV, 3 − : (1316 keV, 3 + , 2 + ): 1117 keV, 2 + ; 1002 keV, 3 + : 877 keV, 4 + ; 689 keV 2 + ; 356 keV, 2 + . The 1446 keV 3 − state is assigned as the lowest octupole vibrational state. Almost all these levels are compared with ones determined from the measurement of the Pt 195 (d, p)Pt 196 reaction. The large excitation of the 3 − state by the stripping process seem to be difficult to understand on the basis of any of the usual theories. The extremely low value of the 689 keV cross over transition from the second excited 2 + state, 689 K/356 K = 1.0±1.0 × 10 −5 is discussed in terms of intrinsic nucleonic excitations.

A Study of the Decay Scheme of Eu146

The level scheme of Sm 146 fed from (4.59±0.03)-days Eu 146 has been investigated with scintillation spectrometers, beta-ray spectrometers, gamma-gamma and Ke - -gamma coincidences, and directional correlation techniques. From the measurements of internal conversion electrons, several new transitions were found in addition to those reported by the previous workers. Levels in Sm 146 were established at the following energies: 750 (2 + ), 1387, 2056, 2287, 2448 and 2686 keV, and also 1654 and 1820 keV. Besides these, about 10 levels were postulated on the basis of energy, intensity and coincidence considerations. From analysis of the positrons and from the fact of absence of crossover transition to the ground state, the spin-parity of the second-excited level at 1387 keV was expected to be 4 + . This assignment, however, was not consistent with the results of the directional correlation measurement for the de-excitation gamma-ray cascade and the K -conversion coefficient for the transition proceeding from t...

Decay of Eu148

The level structure of Sm/sup 148/, which is near the neutron closed shell 82, was studied by analyses of radiations from thc decay of Eu/sup 148/ (54 days) with scintillation spectrometers. The single and the coincidence measurements were made by means of 3 in. x 3 in. and 2 in. x 2 in. NaI(Tl) crystals, and the 5 in. x 4 in. well type NaI(Tl) crystal was also used for searching the level population in the Sm/sup 148/ nucleus. Spins of the levels were determined using the gamma-gamma directional correlation method. The following levels were proposed for Sm /sup 148/; 555(2 plus or minus ), 1183(4+), pared with predictions of models of even-even nuclei. (auth)

Level Structure of Nd144

The energies and spins of lower excited levels in Nd 144 have been established by studies of the beta decay of Ce 144 –Pr 144 and the electron capture decay of Pm 144 . The experiments include the energy and relative intensity measurements, and directional correlation measurements of gamma rays by several NaI (T1) scintillation counters. The level of Nd 144 is populated at the 695 keV and 2190 keV from decay of Pr 144 , and the 695 keV, 1310 keV, and 1780 keV from the decay of Pm 144 . The levels at the 1220 keV and the 1560 keV which have been found by the neutron capture gamma ray measurements could not be found in both decay in the limit of about one percent.

New Level Scheme of Pt 196

In connection with a study of E0 transitions between the first and second 2+ states of Pt194 and Pt196, radiations from 5.6-day Au196 were investigated, and a tentative decay scheme is presented. The level scheme of Pt196 is analogous to that of Pt192.

Decay of I124

The gamma and beta rays following the decay of I 124 which was produced by Sb (α, n ) reaction have been studied with scintillation spectrometers both single and in coincidence, and with a beta-ray spectrometer. Three gamma rays at 2.74–MeV, 2.29–MeV and 1.50–MeV and probably 0.9–MeV which were not found in decay of Sb 124 were observed. The beta-gamma coincidence experiments revealed that the first positron group decays to the ground level of Te 124 so that the energy difference between I 124 and Te 124 becomes 3.22–MeV, being consistent with beta decay energy systematics. In addition this beta component was found to have an unique 1st forbidden type spectrum, showing the spin and parity of the ground state of I 124 is 2–. From these results we led to conclude the presence of two new levels at 2.88–MeV and 2.74–MeV which the spin value is probably 1 and the parity is negative. A doublet level at the second excited level previously reported was not confirmed in the present experiment. However a definite e...

ANGULAR CORRELATION OF GAMMA RAYS FROM Xe

The angular correlation of gamma rays in 2-2-0 cascade transitions in Xe/ sup 126/ and Te/sup 126/ is measunred from the decay of I/sup 126/ in order to obtain the mixing ratio of competing E2 and Ml transitions in the 2-2 transition. The mixing ratio is found to have positive sign for both nuclei, as expected from the systematics of excited levels in even-even nuclei. (auth)The angular correlation of gamma rays in 2–2–0 cascade transitions in Xe 126 and Te 126 is measured from the decay of I 126 in order to obtain the mixing ratio of competing E2 and M1 transitions in the 2–2 transition. The mixing ratio is found to have positive sign for both nuclei, as expected from the systematics of excited levels in even-even nuclei.

sup 126

The angular correlation of gamma rays in 2-2-0 cascade transitions in Xe/ sup 126/ and Te/sup 126/ is measunred from the decay of I/sup 126/ in order to obtain the mixing ratio of competing E2 and Ml transitions in the 2-2 transition. The mixing ratio is found to have positive sign for both nuclei, as expected from the systematics of excited levels in even-even nuclei. (auth)The angular correlation of gamma rays in 2–2–0 cascade transitions in Xe 126 and Te 126 is measured from the decay of I 126 in order to obtain the mixing ratio of competing E2 and M1 transitions in the 2–2 transition. The mixing ratio is found to have positive sign for both nuclei, as expected from the systematics of excited levels in even-even nuclei.