High spin states and multiquasiparticle excitations in odd-odd114, 116Sb nuclei

Abstract

Excited states of ~4'116Sb have been investigated in the 111'113Cd (7Li,4n),) reactions.In both level schemes, two independant parts have been exhibited with, mainly, a negative parity band based on 8-or 7-states and a positive parity sequence based on a 11 § state. The interpretation of the significant levels has been performed in the coreparticle model and in term of quasiparticle configurations mixing, this last approach being able to give a kind of unified description of the whole spectrum.

Electromagnetic moments of the 7+ rotational bandhead in116Sb

“…The obtained results are: /t= +4.69 (10) been located at 776 keV above the 8 long-lived isomer and a half-life of 12.6 ns has been determined for it. This state has also been observed in [ 1] where its half-life was measured as 10.3 ns, and in a very recent l t3In(~, n) study [7]. The occurrence of the positive parity rotational-like band suggests the presence of a deformation which could be also associated to the g9/2 proton-hole excitation known to be responsible for shape coexistence in Sb nuclei [4,5,[8][9][10].…”

“…The observed opposite phases of the modulation patterns of the 350 and 776 keV y-rays are due to the different signs of their angular distribution coefficients [ 1 ]. When the target was solid, the excited Sb nuclei experienced, besides the magnetic interaction, an electric quadrupole interaction due to the EFG created at their sites by the tethragonal polycrystalline In lattice.…”

“…In the second set of experiments, carried out only at the room temperature, a higher magnetic field of 32.2(3)kG has been applied at the target placed inside a 6 mm gap of Time spectra gated by the 350 and 776 keV ?,-rays deexciting the isomeric state have been recorded. They were analyzed by the least-squares method and an average value of 11.9(6) ns was obtained for the half-life of the 7 + isomeric state in 116Sb, which is in good accordance with the previously determined values [1,6]. The normalized and background corrected 7-ray intensities I( _ 135 ~ t) were used to construct the experimental ratio…”

“…These studies have evidenced the presence of two independent branches feeding the 8-60.3 rain isomeric state [3]: (i) a decay sequence through irregularly spaced positive parity levels; (ii) a 7-ray cascade revealing a A I= 1 rotational band developed on a 8-bandhead situated at 1068 keV excitation energy above the long-lived 8-isomer. The occurrence of the negative parity band is a characteristics of the high-spin level schemes of odd-odd H4-1a~ nuclei [1,2,4]. The observed collective structures show strong similarities with the AI= 1 bands build up on low-lying 9/2 + proton-hole states in neighboring odd-mass Sb nuclei [5] and, on this basis, were interpreted as involving the same proton intruder excitation via the [~r (lg9~)| (lhll/2)] configuration.…”

“…The high-spin structure of the odd-odd 116Sb nucleus, having 51 protons and 65 neutrons, is known from investigations via the ~13Cd(VLi, 4n) [1] and ~lSIn(e, 3n) [2] reactions. These studies have evidenced the presence of two independent branches feeding the 8-60.3 rain isomeric state [3]: (i) a decay sequence through irregularly spaced positive parity levels; (ii) a 7-ray cascade revealing a A I= 1 rotational band developed on a 8-bandhead situated at 1068 keV excitation energy above the long-lived 8-isomer.…”