Properties of high-spin states in $sup 95$Tc from $sup 93$Nb($alpha$,2n)$sup 95$Tc* ($gamma$) reaction spectrometry: A test of the cluster-core coupling model

Journal Article · Wed Oct 01 04:00:00 EDT 1975 · Phys. Rev., C, v. 12, no. 4, pp. 1176-1204

OSTI ID:4173997

Sarantites, D G

The structure and properties of the high angular momentum states in $sup 95$Tc up to 5605 keV of excitation have been investigated via measurements of excitation functions of $gamma$ ray singles and $gamma$$gamma$ coincidences following the $sup 93$Nb($alpha$,2n)$sup 95$TC*($gamma$) reaction with $alpha$- particle energies between 17 and 30 MeV. From these experiments and from high- resolution singles energy, angular-distribution, and Doppler-shift attenuation measurements, the position and the decay properties of many high angular momentum state in $sup 95$Tc have been determined. Eleven levels with J/sup $pi$/ values were confirmed, and 14 new levels with J/sup $pi$/ values are proposed. Other possible levels are also suggested. The measured angular distributions provided (i) branching ratios, (ii) J/sup $pi$/ assignments corroborated by deduced angular-distribution attenuation coefficients, level excitation functions and side-feeding yields, and (iii) multipole mixing ratios delta (E2/M1). Lifetimes for nine high-spin levels and limits for four additional ones were obtained by the Doppler-shift attenuation method from measurements with the $sup 93$Nb($alpha$,2n)$sup 95$Tc* ($gamma$) reaction at 18.5, 20.6, 23.6 and 26.7 MeV. The lifetimes were extracted from singles spectra taken 0$sup 0$ and 90$sup 0$ by examining the dependence on E/sub $alpha$/ of the effective level lifetime. For many transitions B(E2) and B(M1) values were obtained. The present results are compared with calculations based on the coupling of three-quasiparticle (g$sub 9$/ $sub 2$$)$$sup 3$ configurations to the quadrupole vibrations of the core, and remarkable agreement is observed for states up to only 19/2$sup +$$sub 1$. This model fails to explain the properties of the higher-spin states with J/sup $pi$/ greater than or equal to 21/2$sup +$.

• Research Organization: Department of Chemistry, Washington University, St. Louis, Missouri 63130 and Research Institute for Physics, 104 05 Stockholm 50, Sweden
• NSA Number: NSA-33-004412
• OSTI ID: 4173997
• Journal Information: Phys. Rev., C, v. 12, no. 4, pp. 1176-1204, Journal Name: Phys. Rev., C, v. 12, no. 4, pp. 1176-1204; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

*TECHNETIUM 95 ALPHA REACTIONS-- ANGULAR DISTRIBUTION-- COMPOUND- NUCLEUS REACTIONS-- ENERGY SPECTRA-- EXCITATION FUNCTIONS-- GAMMA RADIATION-- MEV RANGE 10-100-- NEUTRONS-- NIOBIUM 93
642803*
BRANCHING RATIO-- CLUSTER MODEL-- ENERGY- LEVEL TRANSITIONS-- HIGH SPIN STATES-- MIXING RATIO-- MULTIPOLARITY-- PARITY-- PROBABILITY-- SPIN
N68731* --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
90 <= A <= 149--Energy Levels & Transitions
N68751 --Physics (Nuclear
Experimental)--Nuclear Properties & Reactions
90 <= A <= 149--Nuclear Reactions & Scattering