Theg-factor of the 8+ isomer of142Eu

Theg-factor of the 8⁺ isomer of¹⁴²Eu with mean lifeτ=9 ns, has been measured by the time-differential perturbedγ ray angular distribution (TDPAD) method. The 8⁺ isomer was populated with the reaction¹¹⁴Cd(³²S,p3n)¹⁴²Eu at 155 MeV. The obtained valueg(8⁺)=0.51(3) agrees with shell model calculations using effective single-particle moments taken from neighbouring nuclei. A main configurationπh_11/2?(vh _11/2)^?1 has been confirmed for the 8⁺ isomer.     

The g-factor and the electric quadrupole moment of the 7/2+ isomer in125Xe

The time differential perturbed angular distribution method (PAD) was used to measure theg-factor and the electric quadrupole interaction in a Cd single crystal for thet _1/2=140 ns,I ^π=7/2⁺ isomer in¹²⁵Xe. Theg-factor isg=+0.264(10) and the quadrupole coupling constante ² Qq/h=122.1 (6) MHz at 552 K. The lifetime of theI ^π=11/2⁺ state was measured to beτ=11.3 (1.1) ps by the recoil distance method (RDM). From an analysis of the spectroscopic data using the triaxial-rotor-plus-particle (TRPP) model the quadrupole moment of the 7/2⁺ isomer is deduced to beQ=1.40 (15) b yielding an electric field gradient (efg)eq=3.6(4)·10¹⁷ V/cm² for XeCd.     

High spin states in121Te

High spin states of¹²¹Te, populated in the¹¹⁴Cd(¹¹B,p3n) reaction, have been studied throughγ-ray spectroscopy. The level scheme has been established up toJ ^π=51/2^?. Three-quasiparticle states, based on the πg _7/2 ²?νh _11/2 andπg _7/2 d _5/2?νh _11/2 configurations, have been identified. A favoured 39/2^? state is suggested to be the fully aligned [πg _7/2 ²]₆₊?[νh _11/2 ³ _27/2? yrast non-collective oblate configuration. This assignment is supported by Total Routhian Surface (TRS) calculations which also suggest a similar oblate assignment to the states atJ ^π=21/2^? and 23/2^?. A higher 47/2^? state is also found and is suggested to be the fully aligned [πg _7/2 ²]₆₊?[νh _11/2 ⁵]_35/2? configuration.     

The deformation of the ground and excited states in the Ag and Sn nuclei

The microscopic calculation of the potential energies in the ground and excited states of Ag and Sn nuclei has been performed. The single particle Nilsson potential and the shell correction Strutinski method have been used. The weak sensitivness to nonaxial deformation has been found for even neighbours of these nuclei. The small tendency towards prolate deformation of the ground and excited one-quasiparticle states originating from theg _9/2 proton subshell in^101–105Ag odd isotopes has been noticed. The behaviour with quadrupole e and hexadecapole ε₄ deformation of the ground and two-quasiparticle excited 0⁺ states originating from thed _5/2,g _9/2 andg _7/2 proton subshells andh _11/2 neutron subshell in^112–118Sn has been investigated. The small quadrupole deformation of the excited 0⁺ states has been found what is in agreement with the experimental data concerning the rotational bands build on the first excited 0⁺ states in Sn isotopes.     

g-factor measurement of the two lowest 10+ states in 140Sm

The g-factors of the two 10⁺ states in ¹⁴⁰Sm at 3172 and 3210 keV have been measured by means of the TDPAD method. The obtained values are g = −0.176(20) and g = 1.27(9), respectively. The reaction ¹¹⁶Cd (²⁸Si, 4n)¹⁴⁰Sm, at incident beam energy of 125 MeV, has been used. The measured values clearly show that these states can be described as rather pure (νh_11/2)⁻² and (πh_11/2)² configurations.     

New isomers and states of (πg 9/2 ⊗vg 9/2) parentage in84Rb

Excited states in the doubly-odd nucleus⁸⁴Rb have mainly been studied via the (α,n) reaction by means of in- beam γ-ray spectroscopy. Two new isomers have been found, a 5^? level at 467.1 keV and a 5⁽⁺⁾ level at 544.2 keV with half-lives of 9(2) ns. and 11(1) ns, respectively. On top of the 5⁽⁺⁾ isomer a level sequence with increasing spins up to 10 ? and probably positive parity has been identified. These states are ascribed to the configuration (πg_9/2?vg_9/2).     

Particle × phonon multiplets in 65 147 Tb82

High-spin states of¹¹⁵Sb were studied by inbeamγ-ray spectroscopy using the⁸⁹Y (²⁹Si, 2pn) fusionevaporation reaction at a beam energy of 108 MeV. The experiments includedγ-γ coincidence and directional correlation of oriented nuclei (DCO) ratio measurements using six BGO Compton suppressed Ge detectors. An intruderΔJ=2 rotational band has been identified for the first time and it is interpreted as the h_11/2 proton coupled to a two particle-two hole (2p ? 2h) deformed state of the¹¹⁴Sn core. A ΔJ=1 rotational band based on the 2p ? 1h, π{g ₇ ^2/2 ?g ₉ ^2/?1 }, configuration has been extended to the 29/2⁺ state at an excitation energy of 5241 keV.     

In-beam study of74Br and a first cascade in75Kr

An in-beam study of⁷⁴Br has been carried out using γ-ray spectroscopy in connection with the reactions (³He,p2in) and (d,2n) on⁷⁴Se targets. Separate level schemes on top of the two β-decaying isomers of⁷⁴Br are proposed. Two cascades connecting highspin states are assigned to populate theI ^π=4⁽⁺⁾ isomer. In this level scheme, the excited states at 72.1, 188.3 and 472.0 keV are found to have half-lives of 13.3, 0.7 and 0.7 ns, respectively. The low-spin isomer of⁷⁴Br is tentatively assigned asI ^π=(0^?). This state is populated by two other cascades. For the low-spin levels two-particle configurations of proton and neutron Nilsson orbitals are proposed. The high-spin states are tentatively interpreted as arising from the configurations (πg _9/2,νg _9/2) and (πg _3/2,νg _9/2). As a by-product, a cascade of four transitions has been observed during the³He bombardment of⁷⁴Se and tentatively assigned to negative-parity states in⁷⁵Kr.     

High spin level structure in127Ba produced by the118Sn(12C, 3n) reaction

High-spin states in¹²⁷Ba have been produced by the reaction¹²⁸Sn(¹²C,3n)¹²⁷Ba and studied by in-beamγ-ray spectroscopic techniques. The odd-parity states form a level system based upon a 9/2^? state and generated by an odd neutron in theh _11/2 shell coupled to a triaxial core. Theg _7/2 shell is responsible for theΔ I=1, even-parity band.     

High spin states in 121Te

High spin states of ¹²¹Te, populated in the ¹¹⁴Cd (¹¹B, p3n) reaction, have been studied through γ-ray spectroscopy. The level scheme has been established up to J^π = 51/2^?. Three-quasiparticle states, based on the ^πg _7/2 ² ? vh_11/2 and πg _7/2d_5/2 ? vh_11/2 configurations, have been identified. A favoured 39/2^? state is suggested to be the fully aligned [πg_7/2 ²]6 + ? [vh _11/2 ³]_27/2? yrast non-collective oblate configuration. This assignment is supported by Total Routhian Surface (TRS) calculations which also suggest a similar oblate assignment to the states at J^π = 21/2^? and 23/2^?. A higher 47/2^? state is also found and is suggested to be the fully aligned [πg_7/2 ²]₆+ ? [vh _11/2 ⁵]_35/2? configuration.     

The g-factor of the Jπ=12+ isomeric state in188Hg

Using the reaction¹⁷⁵Lu(¹⁹F, 6n) theg-factor of the¹⁸⁸Hg isomeric state (J ^π=12⁺,T _1/2=135 ns) has been measured with the TDPAD method. The experimental value g=?0.168(10) supports the interpretation of an almost pure (vi13/2)^?2 configuration for this isomer.     

High-spin levels in138Ce and140Nd Observed in the (α, 4n γ) reactions

Levels of¹³⁸Ce and¹⁴⁰Nd have been studied using the¹³⁸Ba(α,4nγ)¹³⁸Ce and¹⁴⁰Ce(α, 4nγ)¹⁴⁰Nd reactions. Singleγ-ray spectra,γ-γ coincidence spectra, angular and time distributions with respect to the beam bursts have been measured. A number of higher excited states with excitation energies up to about 5 MeV and with spin value up to 12 are populated in both nuclei. The lower states with spins and parities 7^?, 5^?, 6^? and 10⁺ can be explained by two-quasiparticle neutron configurations of the types (h _11/2 ^?1 ,d _3/2 ^?1 ) 7^? , (h _11/2 ^?1 ,S _1/2 ^?1 ) 5^?, 6^? and (h _11/2 ^?2 ) 10⁺. Several high-spin states observed in¹³⁸Ce and¹⁴⁰Nd can be explained qualitatively as four-quasiparticle states with two-proton-two-neutron configurations. The 3^? state at an energy of 2,137.4 keV is observed in¹³⁸Ce. The evidence for the existence of the low-lying 3^? states in¹⁴⁰Nd at 2,124.0 keV is discussed. Beside the known 9.6 ms (7^?) isomeric state in¹³⁸Ce another state at 3,538.5keV (10⁺) with a half life of about 200 ns has been observed. The observed levels in the¹³⁸Ce and¹⁴⁰Nd nuclei are compared with theoretical predictions using delta force interaction.     

High spin levels in151Ho

We report here on the first study of the level structure of¹⁵¹Ho. High spin levels in¹⁵¹Ho have been populated in the¹⁴¹Pr+¹⁶O and¹⁴⁴Sm+¹²C reactions. The level structure has been established up to 6.6 MeV energy and the spins and parities determined up to 49/2^?. Most of the proposed level configurations can be explained by the coupling ofh _11/2 protons tof _7/2 and/orh _9/2 neutrons. An isomer with 14±3 ns half-life and a delayed gamma multiplicity equal to 17±2 has been found. Its spin is larger than 57/2? units.     

In-beam study of the doubly-odd nucleus 61 140 Pm79 above the 8− β +-decaying isomer

An in-beamγ-ray study performed with the¹¹⁴Cd(³⁰Si,p 3n) reaction has established the structure of theN=79 nucleus¹⁴⁰Pm. States up toI=(20)? and 5.5 MeV excitation energy have been recognized above the 5.95 m isomeric state which we identify, from the GT decay to¹⁴⁰Nd, as the 8^? member of the (πd ₅ ^2/?1 vh ₁₁ ^2/?1 ) multiplet, changing the present 7^? assignment. The low energy part of the level scheme is discussed in terms of the coupling of the valence holes in respect to theZ=64,N=82 shell closure. A new 8⁺ isomeric state witht _1/2=1 _?0.5 ⁺¹ ns has been observed, having most likely a (πh _11/2 vh _11/2 ^-1 )₈ configuration.     

Excited states and terminating bands in123,124I

High spin states in^123,124I were populated via the¹¹⁶Cd(¹¹B,xn) reaction at 38 MeV bombarding energy and via the¹¹⁰Pd(¹⁸O,pxn) reaction at 75 MeV energy. γ-ray energies, intensities, γγ coincidences and DCO ratios were measured with the GASP spectrometer. The level schemes were extended considerably. Band terminations were observed in both nuclei. In¹²³I the rotational band, which is built on the πh _11/2 single-particle state was extended to spinI ^π=(35/2)^?; at higher spin the level spacings and the feeding pattern were found to become irregular, indicating a structure change. The (39/2)^? state and the higher-lying (43/2)^? level were interpreted as aligned oblate states. In¹²⁴I a decoupled band was found to terminate in the same spin region. Total Routhian surface calculations were performed which support the occurrence of a band termination.     

Observation of band structures in the odd-odd nucleus126La

The odd-odd nucleus¹²⁶La has been studied in the reactions¹¹¹Cd(¹⁹F,4n) and⁹³Nb(³⁷Cl,p3n). Three band structures have been identified, two of them having both signature members and ΔI=1 character. These are proposed, respectively, to have πh_11/2 ? νh_11/2 and πh_11/2 ? νg_7/2 configurations and tentative 4⁺ and 3^? band heads.     

Yrast states in the doubly-odd nucleus100Tc

High spin states up toJ=14 and excitation energy up toE ^*=3076 keV have been observed in the odd-odd nucleus¹⁰⁰Tc with the reaction⁹⁶Zr(⁷Li, 3n), at bombarding energies between 21 and 31 MeV, by in-beam γ spectroscopy and conversion-electron measurements. A ΔJ=1 negative parity band similar to that observed in theN=57 isotone¹⁰²Rh, and based on the 8^?, 708 keV state has been identified. The observed band can be interpreted in terms of collective core excitations based on a two-quasiparticle state of(πg_9/2 ? νh_11/2) configuration. Comparison with IBFM-2 calculations have been performed.     

Nuclearg-factors of theJ π=21/2+isomer in112In and theJ π=6+ 112Sn

Theg-factor of theJ ^π=21/2⁺ isomeric state in¹¹¹In (T _1/2=13.3 ns) and of theJ ^π=6⁺ isomeric state in¹¹²Sn (T _1/2=13.7 ns) were measured using the spin rotation method. The result obtained for theJ ^π=21/2⁺ level in¹¹¹In,g=+0.47 (2), indicates that this state has an almost pure ((πg _9/2)^?1 νg _7/2 νd _5/2) shell model configuration. The experimental valueg=+0.04 (3) for theJ ^π=6⁺ isomer in¹¹²Sn agrees with the theoretical value calculated within the frame of the BCS model.     

High-spin levels in137,139Ce and139,141Nd evidence for hole-core coupling

Excited states of the¹³⁷Ce,¹³⁹Ce,¹³⁹Nd and¹⁴¹Nd nuclei have been studied using the¹³⁸Ba(α, 5nγ)¹³⁷Ce,¹³⁸Ba(³He, 4nγ)¹³⁷Ce,¹³⁸Ba(α, 3nγ)¹³⁹Ce,¹⁴⁰Ce(α, 5nγ)¹³⁹Nd,¹⁴⁰Ce(³He,4nγ)¹³⁹Nd,¹⁴⁰Ce(α, 3nγ)¹⁴¹Nd and¹⁴²Ce(α, 5nγ)¹⁴¹Nd reactions. Singlesγ-ray spectra,γ —γ coincidence spectra, angular distributions and time distributions ofγ-rays with respect to beam pulses have been measured. Gamma transitions between excited states with spin values up to 21/2, 23/2 or 25/2 have been observed. Isomeric states with T_1/2=70 ns have been observed in¹³⁹Ce at 2631.5 keV (19/2) and in¹⁴¹Nd probably at 2952.0 keV (19/2). The level structure observed in the nuclei studied can be explained if the neutron-holes are coupled to the doubly even core excitations. The coupling of theh _11/2 neutron-hole with the 2⁺, 4⁺ and 3^? collective excitations are calculated in terms of the weak and intermediate coupling models. The intermediate coupling results seem to be in better agreement with the experimental data. The energies of theree-particle states, being the result of the coupling of theh _11/2 neutron-hole with the two-proton excitations in the core, are well reproduced in the calculations when empirical values of the two-body interaction matrix elements were used.     

Observation of a new deformed structure in114Sn

Yrast as well as non-yrast states of¹¹⁴Sn have been investigated via the¹⁰⁰Mo(¹⁸O,4n) and the¹¹²Cd(,2n) reaction by means of in-beam-ray spectroscopy using the Compton-suppressed germanium detector array OSIRIS-Cube. A new rotational band including the band head with a tentative spin and parity assignment of 5^– could be placed in the level scheme and might be a candidate for ag ₉ ^2/–1 h_11/2 intruder band.