0000000000030870
AUTHOR
H. Helppi
In-beam study of the 128, 130Xe nuclei
Abstract The level structure of 128,130Xe has been studied in the (α, 2nγ) and (3He, 3nγ) reactions on enriched Te targets using in-beam γ-ray spectroscopic methods. For both nuclei the existing information about positive-parity level structure was enriched and many new negative-parity two-quasiparticle states were observed. Isomeric states with the half-lives of 63 ± 12 ns in 128 Xe and 4.8 ± 0.5 ns in 130 Xe were found. For collective positive-parity states the interacting boson model, and calculations based on Bohr hamiltonian were compared with the experimental data.
Low-lying levels of201Hg from the decay of201Au
The decay of 26.4-min201Au has been investigated using chemically separated sources and Ge(Li), Si(Li), plastic and Nal(Tl) detectors in different singles and coincidence arrangements. The β-disintegration energy was measured to be 1.27 ± 0.10 MeV. Thirteen γ-rays were observed to belong to this decay and the new levels at 543, 549.2, 552.8, 559.1, 605.7, 645.4, 732 and 1188 keV were established in201Hg, in addition to the three previously known excited states below 200 keV.
Asymmetric linear Ge(Li)Ge(Li) sum-peak coincidence spectrometer
Abstract An asymmetric linear Ge(Li)Ge(Li) sum-peak coincidence spectrometer configuration has been designed and tested. In this system, the ratio of the gains of two detector-amplifier chains is chosen around 1.2 to 1.3, and the pulse amplitudes or addresses due to coincident events are summed. The simple method introduced involving a single run which results in two spectra (separated according to which detector records the larger energy) appears to be quite useful in γγ coincidence and directional correlation measurements, especially in laboratories where no event-by-event data acquisition hardware are available.
Nuclear Shape Transitions and Some Properties of Aligned-Particle Configurations at High Spin
Two topics are addressed in this paper. First, we discuss the variation of shapes with spin and neutron number for nuclei in the N approx. = 88 transitional region. Second, we present comments on the feeding times of very high spin single-particle yrast states.
Decay of 14.6 h90Nb
The disintegration of 14.6 h90Nb produced by bombarding natural Zr with 13 MeV protons was investigated by methods of γ-ray spectrometry. Results from singles, coincidence and anti-Compton spectrometer measurements are reported. A decay scheme is proposed including excited states in90Zr at 1761, 2186.4, 2319.1, 2739.4, 2747.9, 3077.0, 3448.2, 3589.5, 3977.1, 4232.4, 4319.5, 4375.4, 4541.6, 5060.0, 5164.6 and 5432.9 keV. Over 10 γ-ray transitions and several levels proposed in an earlier investigation are shown to be in error.
Simultaneous recording of true and random coincidences using a two-parameter analyzer system
Abstract A description is given of a simple fast coincidence method which allows the simultaneous recording of coincidence and random coincidence spectra. The method is based on the properties of a standard two-parameter pulse-height analyzer system, and no special electronics is required.
Note on the decay of200Au
Gamma and beta rays from the decay of200Au (48.4 min) were studied employing Ge(Li) and plastic detectors in various singles and coincidence arrangements. The intensity of the β-branch to the ground state of200Hg was determined as 79%, and the disintegration energy of200Au to be asQβ=2.26 ± 0.06 MeV. A tentative spin and parity assignment of (1,2)+ is proposed for levels at 1515.2 and 1972.5 keV in 200Hg
Directional correlations of some γ-ray cascades in200Hg
Directional correlation functions of 10 γ-ray cascades in200Hg have been measured using a200Tl source and a Ge(Li)-NaI(Tl) coincidence spectrometer arrangement. Values of the mixing parameter δ for several transitions are determined, and the spin assignments for the following levels in200Hg are established (level energies are given in keV): 1029.4 (0+), 1254.2 (2+), 1573.7 (2+), 1593.4 (2+), 1641.5 (2+), 1730.9 (2+) and 1775.6 (3+).
Study of band crossings in 130Xe
Abstract Excited states in 130Xe were populated in the reaction 130 Te (α, 4 n ) , and the subsequent de-excitation was studied using in-beam γ-ray spectroscopic methods. High-spin states were observed to a possible spin of 19 kh at an excitation energy of 7 MeV. Band-crossings due to h 11 2 neutrons and protons were observed. The triaxial cranked shell model was applied in order to study the quasiparticle content of different bands. Excitation energies of two-quasiparticle states were calculated in the framework of the semiempirical shell model.