γ-ray spectroscopy ofTa163

Nuclear Physics, 1998

Six rotational bands in the odd-odd nucleus IV4Ta have been populated with the I('"Gd(I'~F,5n) reaction. High-spin states were identified using the NORDBALL array. Both signatures of the doubly decoupled zrl/2-[541 ] @, ~, I/2-[521 ] band and semi-decoupled 7rl/2-[541 ] ~ u7/2 ~ [633 I band are observed, in addition to the high-K couplings of the zr9/2-[514] ~4 ~,7/2 ~ [6331, zr9/2-[514] @ u5/2-[512], 7r7/2 + [404] C, u7/2+[6331, and 7r5/2+ [402] @ u5/2-1512] configurations. The signature splitting of the ~-1/2-[541] @ ~,7/2 ~ [633] band is inverted l'rom the expected splitting, and this is interpreted as being due to a residual proton-neutron interaction. It is shown empirically that this interaction, together with deformation changes, can account for the increased crossing frequency associated with the alignment of i~/2 neutrons in the 7rl/2-15411 bands of odd-Z nuclei. @ 1998 Elsevier Science B.V.

Nuclear Physics A, 1995

Excited levels of the strongly-deformed odd-odd nucleus 166Tm, populated by the 165Ho(a,3ny) reaction, were investigated using standard in-beam y-ray spectroscopy, including measurements of a few conversion electron lines, and by high-resolution curved-crystal spectroscopy. A level scheme consisting of 178 transitions among 6 well-developed and 4 partial rotational bands is proposed. Level spins and parities were determined and the results were interpreted in the framework of the Nilsson model by comparison with predictions. The Gallagher-Moszkowski splitting for 5 + the {~r½ + [411 ] 4-v~ [642] } configuration was determined to be 245(20) keV. An anomalous signature splitting was observed for the {*r 7+ [404] + v 5+ [642] }K" = 6 + configuration.

Nuclear Physics A, 1985

High-spin data are presented for 17°Ta and tTl Ta for the first time, and the known level scheme of 173Ta is extended to higher spins. Anomalies found in the crossing frequencies for the alignment of a pair of neutrons are considered. At high spin a large and constant value of j(2), with j(2) > j(t), is found for two tTl Ta bands and the implications of this are discussed. The *ril3/2 [660].~ +, t~ = + t z orbital is identified as it crosses the rotational band built on the [402]~ +, a = + ~ orbital in 171Ta. Magnetic transition probabilities obtained from measured branching ratios show the effects of the aligning pair of neutrons and the spectator orbital. The data are interpreted using cranked shell-model calculations and a semiclassical vector-coupling scheme developed by Donau and Frauendorf. E NUCLEAR REACTIONS 159Tb(t60,4n), E = 72-84 MeV; t59Tb(lsO,4n), E = 84 MeV; 124Sn(StV, xn), E=230 MeV; measured yy-coin, "r(0). 17°'171"173Ta deduced levels, J, *r, TI/2, B(MI), rotational band moments of inertia. Cranked shell-model analysis. Enriched targets.

Physical Review C, 2011

Excited states in the neutron-deficient odd-Z nuclide 161 Ta were identified for the first time using the 106 Cd(58 Ni,3pγ) reaction at a beam energy of 270 MeV. The πh 11/2 band, yrast at low spin, was observed up to (47/2 −) and a further four strongly coupled bands have been established to high spin. Quasiparticle configuration assignments for the new band structures have been made on the basis of cranked shell model calculations. This work suggests that the negative-parity ν(f 7/2 , h 9/2) orbitals are responsible for the first rotational alignment in the πh 11/2 band.

Physical Review C, 2006

The nuclear g-factors of the one-quasiparticle isomeric state 9 2 − at 165.8 keV and the three-quasiparticle isomeric state 21 2 − at 1713.2 keV in 173 Ta nuclei have been measured using the time differential perturbed angular distribution technique. The nuclear reaction 165 Ho( 12 C, 4nγ ) 173 Ta was used to populate these isomeric states, and the recoiling 173 Ta nuclei were implanted into a thick tantalum backing in the presence of a 7.04(4) kG external magnetic field. The measured value g( 9 2 − ) = +0.591(18) shows that the 9 2 − isomeric state is not a pure single-particle state but may have a collective contribution due to the octupole excitation of the core. Based on the measured value g( 21 2 − ) = + 0.620 and multi-quasiparticle calculations, the 21 2 − isomeric state is assigned a mixed configuration: π 3 { 9 2 − [514], 7 2 + [404], 5 2 + [402]} (39%) and π 1 { 7 2 + [404]}⊗ ν 2 { 7 2 − [514], 7 2 + [633]} (61%).

Physical Review C, 2016

Excited states in the neutron-deficient odd-odd proton-unbound nuclide 158 Ta have been investigated in two separate experiments. In the first experiment, 166 Ir nuclei were produced in the reactions of 380 MeV 78 Kr ions with an isotopically enriched 92 Mo target. The α-decay chain of the 9 + state in 166 Ir was analyzed. Fine structure in the α decay of the 9 + state in 162 Re established a 66 keV difference in excitation energy between the lowest-lying 9 + and 10 + states in 158 Ta. Higher-lying states in 158 Ta were populated in the reactions of 255 MeV 58 Ni ions with an isotopically enriched 102 Pd target. Gamma-ray decay paths that populate, depopulate, and bypass a 19 − isomeric state have been identified. The general features of the deduced level scheme are discussed and the prospects for observing proton emission branches from excited states are considered.

Physical Review C, 2022

Excited levels of 130 Te were studied with the (n, n γ) reaction. Excitation functions, γ γ coincidences, angular distributions, and Doppler shifts were measured for γ rays from levels up to an excitation energy of 3.3 MeV. Detailed information that includes level lifetimes, multipole-mixing ratios, branching ratios, and electromagnetic transition rates deduced from these measurements is presented. Large-scale shell model calculations performed with all proton and neutron orbitals in the 50-82 shell are compared to these data, with generally good agreement, particularly for the positive-parity states. To investigate emerging collectivity in 130 Te, the Kumar-Cline sum rules were used to evaluate rotational invariants from the shell model calculations. Whereas the ground state and first-excited state show the greatest average deformation, as expected, all of the low-lying states are weakly deformed and triaxial.

Physical Review C, 2000

Excited states in 111 Te have been studied using the 4pn evaporation channel from the 58 Niϩ 58 Ni reaction at a beam energy of 250 MeV. A thin-target experiment was carried out using GAMMASPHERE coupled with the MICROBALL charged-particle detector array and an array of neutron detectors. A complementary thicktarget experiment was performed with the Stony Brook six-Ge-detector array in order to measure the lifetime of an 11/2 Ϫ isomer observed in the GAMMASPHERE data. The structure of 111 Te at low spin is dominated by the yrast h 11/2 band, although a band assigned to the (g 7/2 d 5/2) configuration is also observed. Four collective bands have been found at higher spins. Experimental results are compared to the odd-A Te systematics and to core-quasiparticle and total Routhian surface calculations.

Physical Review C, 2001

Excited states in 165 Ta were populated in the 142 Nd(27 Al,4n) 165 Ta and 141 Pr(28 Si,4n) 165 Ta reactions and investigated using the AFRODITE array. The yrast rotational decay sequence up to spin 53/2 Ϫ is identified and assigned to the ͓514͔9/2 Ϫ configuration. The nuclear shape is investigated using total Routhian surface calculations. The experimental results are discussed in relation to existing data in the neighboring Ta isotopes and results from cranked shell model calculations. Unexpectedly large signature splitting, for a high-⍀ configuration, is observed in the yrast band. Further discrepancies are observed between theoretical and experimental values for the band crossing frequency and signature splitting of the B(M 1)/B(E2) ratios. The possibility that these discrepancies are a consequence of a large deviation from an axially symmetric nuclear shape is investigated.

Physical Review C, 2010