Fast nuclear rotation and octupole deformation

The Sm-150 nucleus has been studied to high spins in a measurement of gamma radiation following the Xe-136 (O-18,4n) Sm-150, compound-nucleus reaction at beam energy of 76 MeV. The measurement was performed at NBI Riso using the NORDBALL array. Alternating parity, epsilon = +1 band in Sm-150 has been observed up to spin I = 22. This band is crossed by two aligned bands, corresponding to a reflection-symmetric shape. After the second crossing the s = +1 band ends abruptly, suggesting that the octupole shape vanishes in Sm-150 above spin I = 22, as predicted by calculations. Other explanations, assuming continuation of the s = +1 band past the two alignments are also discussed

Fast nuclear rotation and octupole deformation

The Sm-150 nucleus has been studied to high spins in a measurement of gamma radiation following the Xe-136 (O-18,4n) Sm-150, compound-nucleus reaction at beam energy of 76 MeV. The measurement was performed at NBI Riso using the NORDBALL array. Alternating parity, epsilon = +1 band in Sm-150 has been observed up to spin I = 22. This band is crossed by two aligned bands, corresponding to a reflection-symmetric shape. After the second crossing the s = +1 band ends abruptly, suggesting that the octupole shape vanishes in Sm-150 above spin I = 22, as predicted by calculations. Other explanations, assuming continuation of the s = +1 band past the two alignments are also discussed

High-spin parity doublets in the nucleus 151 Pm

The high-spin-level structure of the nucleus 151Pm has been investigated by in-beam γ-ray spectroscopy using the 150Nd(α, p2N) 151Pm reaction. The observed enhanced E1 transitions with B(E1) of the order of 10-3 W.u. and parity doubling, both features characteristic of a reflection-asymmetric mean field, suggest an octupole deformation in 61151P

Observation of strongly deformed shapes in 154-152Dy nuclei at medium temperatures

The gamma-decay of the giant dipole resonance (GDR) built on excited states of 154-152Dy nuclei is studied. The selection of GDR decay from high spin states leading to specific exit channels was made possible by triggering on high spin isomers. The deduced energy splitting of the GDR implies large deformations (\beta\ congruent-to 0.4-0.5). The resonance widths of the components are comparable to those of the GDR built on the ground state indicating small shape fluctuations

DEVELOPMENT OF A SPECIAL ANTI-COMPTON SPECTROMETER

This paper describes the investigation of the possibility to build a compact anti-Compton spectrometer consisting of a Ge detector and a cooled BGO suppressor. Monte Carlo calculations were carried out to obtain information about the performance of two different detector configurations. Light output and timing properties of a BGO-photodiode detector have been measured as a function of temperature and will be compared with computer simulations of light output