Study of 170,171,173Ta isotopes at high spinṡ (original) (raw)
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High-spin study of odd- A 49In isotopes beyond the neutron mid-shell
The European Physical Journal A, 2002
The 115,117,119,121 In nuclei have been produced as fission fragments in three reactions induced by heavy ions: 12 C + 238 U at 90 MeV bombarding energy, 18 O + 208 Pb reaction at 85 MeV, and 31 P + 176 Yb at 152 MeV. Their level schemes have been built from gamma-rays detected using the EUROBALL III and IV arrays. High-spin states of 117,119,121 In nuclei have been identified for the first time. Moreover, isomeric states lying around 2.5 MeV have been established in 119,121 In from the delayed coincidences between the fission fragment detector SAPhIR and the gamma array. Most of the observed states can be described by coupling a proton g 9/2 hole to a Sn core, while the intruder band based on an orbital from the π[g 7/2 /d 5/2 ] sub-shells behaves as the ground-state band of neighbouring Cd isotopes.
Physical Review C, 2012
Five N = 82 isotones have been produced in two fusion-fission reactions and their γ rays studied with the Euroball array. The high-spin states of 139 La have been identified for the first time, while the high-spin yrast and near-to-yrast structures of the four others have been greatly extended. From angular correlation analysis, spin values have been assigned to some states of 136 Xe and 137 Cs. Several cascades involving γ rays of 139 La have been found to be delayed, they deexcite an isomeric state with T 1/2 = 315(35) ns located at 1800-keV excitation energy. The excited states of these five N = 82 isotones are expected to be due to various proton excitations involving the three high-j subshells located above the Z = 50 shell closure. This is confirmed by the results of shell-model calculations performed in this work. In addition, high-spin states corresponding to the excitation of the neutron core have been unambiguously identified in 136 Xe, 137 Cs, and 138 Ba.
Nuclear Physics A, 1991
High-spin states in '73 OS have been studied by yy-coincidence measurements following the 's6Nd(32S, 5n)'730s reaction. Additional information has also been extracted from the reaction '44Sm(3'S, 2pn)"'Os. Four main sequencies have been identified as the two signature branches of the bands built on the [642]$+ and [523]$-Nilsson states. The band features have been analysed within the framework of the cranked shell model. The positive-parity band provides evidence for a v(i,3,2)2 crossing at low frequency and a r(h,,,,)' and/ or r(hg,?)' crossing at higher frequency. In the negative-parity band the upbend starts at relatively low frequency indicating, presumably, an early v(i,,,z)' alignment. There is evidence for another two band crossings possibly due to u(i,,,,)' alignment of a different configuration and a high frequency proton alignment as in the positive-parity band. B(Ml)/ B(E2) ratios have also been extracted in both bands to deduce further information on the detailed structure of the bands. NUCLEAR REACTIONS '46Nd(3ZS, 5n), E = 166 MeV; '44Sm(3'S, 3pn). E = 163 MeV; E measured yy-coin. '730s deduced levels, J, T, configurations, alignments, E(Ml)/B(E2J ratios.
High-Spin Structures of the Odd-A 97 - 105 43 Tc Isotopes
Acta Physica Hungarica, 2001
The 99-105Tc isotopes have been produced at high spin as fission fragments following the fusion reaction 37Cl(170 MeV) +176Yb and studied with the Euroball3 array. The high-spin structures of 103Tc have been identified for the first time. From the systematics of the yrast states of 97-105Tc, the location of individual proton states can be analyzed as a function of the neutron number.
Band structures and proton-neutron interactions in 174Ta
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.
The unpaired spectroscopy of 161,162Er at spins up to 50ħ
Nuclear Physics A, 1990
High spin states in 161Er and 162Er have been populated using the 13°Te + 3SS reaction at a bombarding energy of 170 MeV. In ~S~Er, three rotational bands were extended from 1=35h to 1=50h. In ~62Er the positive parity yrast band was observed to 1=445. These rotational sequences are compared to a simple unpaired model which was successful in predicting the behaviour of similar high spin data on 159'~6°Er. These studies of the light Er isotopes constitute the highest spins observed in normal deformed nuclei and yield direct and specific information on the single-neutron spectrum of states.
High-spin structures of 124−131Te: Competition of proton- and neutron-pair breakings
The European Physical Journal A, 2014
The 124−131 Te nuclei have been produced as fission fragments in two fusion reactions induced by heavy ions ( 12 C + 238 U at 90 MeV bombarding energy and 18 O + 208 Pb at 85 MeV) and studied with the Euroball array. Their high-spin level schemes have been extended up to 6 MeV (even-A) and 5 MeV (odd-A) excitation energies from the triple γ-ray coincidence data. The γ-γ angular correlations have been analyzed in order to assign spin and parity values to most of the observed states. Moreover the half-lives of isomeric states have been measured from the delayed coincidences between the fission-fragment detector SAPhIR and Euroball, as well as from the timing information of the Ge detectors. The behaviors of the yrast structures identified in the present work are first discussed in comparison with the general features known in the mass region, particularly the breakings of neutron pairs occupying the νh 11/2 orbit identified in the neighboring Sn nuclei. The experimental level schemes are then compared to shell-model calculations performed in this work. The analysis of the wave functions shows the effects of the proton-pair breaking along the yrast lines of the heavy Te isotopes.
High-spin structures of 77,79,81,83 As isotopes
Modern Physics Letters A, 2015
In this paper, we report comprehensive set of shell model calculations for arsenic isotopes. We performed shell model calculations with two recent effective interactions JUN45 and jj44b. The overall results for the energy levels and magnetic moments are in rather good agreement with the available experimental data. We have also reported competition of proton- and neutron-pair breakings analysis to identify which nucleon pairs are broken to obtain the total angular momentum of the calculated states. Further theoretical development is needed by enlarging model space by including [Formula: see text] and [Formula: see text] orbitals.
High spin states in the transitional nucleus88Mo
Zeitschrift f�r Physik A Hadrons and Nuclei, 1992
The reaction 58Ni(36Ar, c~qp)88Mo has been studied at 145 MeV beam energy. A detector array consisting of the OSIRIS spectrometer, four charged-particle A E detectors and seven NE213 neutron detectors has been used to meaure the gamma radiation in 77-and particle-y y-coincidence mode. The level scheme.of SSMo has been extended up to 11.6 MeV excitation energy and probable spin 23h; some 70 transitions and 40 levels have been identified. Spin assignments have been proposed on the basis of measured DCO ratios. Hartree Fock cranking calculations of the Total Routhians and shell model calculations of the high spin states are presented which imply near-sphericity of the yrast line up to the highest spins found. A classification of the high spin states according to their leading seniority is proposed.
New insights into neutron-rich nuclei at high spin
The European Physical Journal A - Hadrons and Nuclei, 2002
With new high statistic data, new isotopes and new high-spin structures are observed in neutronrich nuclei populated in the spontaneous fission of 252 Cf. The 135 Te levels are extended, and many new levels in 139,141 Ba observed. The coexistence of collective and single particle-hole states is found in 135 Te. The N = 83 135 Te and 139 Ba show marked differences associated with differences in their particle and hole states. New levels in 141 Ba complete evidence for two opposite-parity doublets characteristic of stable octupole deformation. In 114,116 Pd a second backbend is observed for the first time in this mass region and the backbend in 118 Pd occurs earlier than in 112-116 Pd because of a reduction in pairing. Gamma-type vibrational bands are seen up to 13 + to 15 + in 104,106 Mo, 108-112 Ru, and 112-116 Pd. Their behavior reflects prolate to triaxial shapes in these nuclei. The levels of 162,164 Gd are observed for the first time. As N increases toward mid-shell at 104, the moments of inertia in N = 100 164 Gd show an unexpected decrease compared to N = 98 162 Gd. The levels in 162,164 Gd form remarkable shifted identical bands with nuclei separated by 2n, 2p, α, and 2α.