Triaxiality-related nuclear phenomena in the A ≈ 100 mass region

J Timár,J Meng,S.Q Zhang,P Joshi,B Kruzsicz,B M Nyakó,R Wadsworth,K Starosta,J Molnár,D Sohler,Q.B Chen,T Koike,I Kuti

doi:10.1088/1742-6596/1555/1/012025

Abstract

Solid experimental evidence for triaxial nuclear shape is difficult to obtain and is quite rare. Such evidence can be provided by the phenomena of chiral rotation and wobbling motion, as these can occur only in triaxially deformed nuclei. Although nuclear chirality is well documented in different mass regions, experimental evidence for multiple chiral bands as well as for wobbling motion has been reported so far only in a few nuclei. Pd and Rh nuclei in the A ≈ 100 mass region have been recently studied, and transverse wobbling motion as well as multiple chiral band structures were identified for the first time in this region. These observations provide experimental evidence for the predicted triaxial shape in this mass region, and new data which enable a better understanding of the studied phenomena.

Highlights

Observed rotational spectra in nuclei show us that many nuclides have deformed shape
The special rotational band structure corresponding to one of these exotic rotations can provide a key evidence for stable triaxial shape of the nucleus at medium to high angular momentum
In order to search for multiple chiral doublet bands in the A ≈ 100 mass region, we have studied the medium- and high-spin band structures of 103Rh based on the high-statistics data set measured with the Gammasphere spectrometer at LBNL using the 96Zr(11B,4n) fusionevaporation reaction at a beam energy of 40 MeV

Summary

Introduction

Observed rotational spectra in nuclei show us that many nuclides have deformed shape. Nuclear chirality was predicted by Frauendorf and Meng about two decades ago [5] They have shown that at certain configurations of the active valence nucleons in a rotating triaxial nucleus the total angular momentum vector can lie outside the three principal planes in the intrinsic frame. It is seen that the PRM with h11/2 configuration calculations can reproduce the data of bands A and B well up to the angular momentum of about 35/2 ̄h At higher spins both in bands A and B the configuration changes due to the gradual alignment of a pair of h11/2 neutrons and of g9/2 protons, respectively. The calculations reproduce well the electromagnetic properties of the transitions in the wobbling bands These results prove the occurrence of transverse wobbling motion in 105Pd, which is the first observation of wobbling in this mass region and in a nucleus with odd neutron number [16]. The mixing ratios could not be deduced for them

Multiple chiral doublet bands in 103Rh and 104Rh

Conclusion