0000000000146710
AUTHOR
H. Ryde
The distribution of the rotational transition strength in warm nuclei studied through γ-ray correlations
Abstract The study of damping of rotational motion applying te rotational plane mapping (RPM) method is presented and discussed. The aim of this technique is to extract the distribution of the rotational transition strength from an analysis of the shape of the “central valley” of two- and three-dimensional γ-ray spectra. The method is applied to a triple γ-coincidence data set of 162,163Tm nuclei formed in 37Cl+130Te reactions. The rotational transition strength is obtained as a function of rotational frequency for selected regions of entry states, and the width is found to be rather constant and approximately equal to 80 keV. This value is significantly smaller than the value predicted the…
On the decay of compound nuclei following alpha-particle and12C induced reactions
Multiple coincidence rates have been measured using a detector system consisting of a Ge(Li) spectrometer and eight NaI(Tl) or eight liquid scintillators. Reactions induced byα-particles with energies of 51–55 MeV and 118 MeV12C ions are studied. The data are analysed to give the first and second central moments of the distribution of the number ofγ-rays feeding individual levels in the final nuclei. When these numbers are compared to spin distributions calculated with the statistical model code GROGI the relative importance of dipole and quadrupole deexcitation modes can be ascertained. In particular, in the122Te(α, 4n)122Xe reaction theγ-decay prior to the entry into the ground band is we…
Interaction strength and shape difference for the h9/2 and h11/2 configurations in163Tm
The strongly shape driving πh9/2[541]l/2− configuration with α=+1/2 exhibits some anomalous, and so far unexplained, features concerning the crossing frequency, ħωc, the aligned angular momentum, ix, and interaction strength, at the alignment of the first pair of i13/2 quasineutrons in several odd-Z rare earth-nuclei. The h9/2[541]1/2− and h11/2[523]7/2− bands have been studied in the stably deformed rare-earth nucleus163Tm to investigate these features. A difference in band crossing frequency of ∼ 80 keV between the two bands is found. Rotational bands built on these two configurations have been found to cross in the spin range I=25/2–29/2 ħ. Theγ-decay pattern between the two bands is est…
TERMINATING STATES IN Z = 71Lu NUCLEI WITH N ≈ 90
The high-spin yrast states in 161 Lu are calculated in a Cranked Nilsson-Strutinsky approach keeping track of configurations and their evolution with spin. The outcome from calculations neglecting pairing and including pairing are compared. It is predicted that several yrast region configurations terminate at a very favored energy around I = 50 and that one of the observed bands is two transitions short of termination.
Search for High-Spin Isomers in 150Dy
A search for yrast traps in 150Dy has been made by studying the γ-ray decay following the 144Nd (12C, 6n) 150Dy and 146Nd (12C, 8n) reactions. Although an average value of about 30 units of angular momentum is imparted to the final nucleus using these reactions, no evidence is found for the existence of isomers with half-lives longer than 10 ns.
High spin shell model excitations in149Gd
The high spin level structure of the three-neutron nucleus149Gd has been investigated by in-beamγ-ray and electron spectroscopy with (α, xn) reactions. The observed levels are characterized as members of the shell model multipletsνf 7 2/3 ,νh 9/2 f 7 2/2 ,νf 7 2/3 ×3−,νh 9/2 f 7 2/2 ×3−, and tentativelyνf 7 2/3 ×(3−)2. The energies of theν f 7 2/3 states agree only moderately with those calculated using empirical two-nucleon interactions taken from148Gd, which indicates the importance of long range contributions already atN=85.