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1.
High-spin levels in 122Xe have been investigated by γγ coincidence measurements using the EUROGAMarray. The reaction 96Zr(30Si,4n)122Xe at a beam energy of 135 MeV was used. New structures of competing dipole to quadrupole transitions have been observed. Experimental B(M1)/B(E2) ratios have been extracted and compared with theoretical estimates.  相似文献   

2.
High spin states of118Xe have been investigated by means of γ ray spectroscopy using the92Mo(29Si,2pn) at a bombarding energy of 110 MeV. Several new side bands as well as the yrast band were established. A band crossing between the ground state and super bands was observed at ?ωc = 0.39 MeV. A negative parity band with two quasi particle excitation, and a quasi γ band were also identified.  相似文献   

3.
High-spin structures in the neutron-rich nuclei138Xe and139Xe have been investigated by observing prompt γ -rays from the spontaneous fission of248Cm with the Eurogam spectrometer. The partial level schemes were constructed on the basis of double-, triple- and quadruple-γ coincidences. The ground state band in138Xe has been extended up to 5 MeV excitation energy. The structure of the newly observed medium-spin states in139Xe is similar to the one of heavier N=85 isotones where vf 7 2/3 , vh9/2f 7 2/2 and vf 7 2/3 ? 3? multiplets have been observed.  相似文献   

4.
Calculations on the basis of the extended interacting-boson approximation have been made for the positive-parity states of122–130Xe. The results of the calculations are compared with their energy levels, expecially the backbendings in the yrast bands, and with reducedE2 transition probabilities andg-factors. They are also compared with the staggerings in theγ-vibrational quasibands. The present calculations reproduce the experimental data concerning122–130Xe.  相似文献   

5.
Excited states of the nuclei127Xe and125Xe have been investigated in the inverse kinematic reactions48 Ca(82 Se,(3.5)n) at 275 MeV beam energy with the OSIRIS multidetector system at the VICKSI-accelerator of the HMI Berlin. The level scheme of127Xe was extended up to a level of tentative spin (51/2?). Two excited bands of 3QP-character were observed. For125Xe these structures were extended towards higher spins. Experimental Routhians of selected bands are presented.  相似文献   

6.
The level scheme of91Nb has been investigated with the reaction90Zr(p, γ)91Nb. Proton energies between 3.0 and 7.2 MeV were used. The γ spectra were taken with Ge(Li) detectors. Primary γ transitions to 36 excited states of91Nb up to 3.8 MeV excitation energy and many secondary γ transitions from the decay of those states were observed, leading to an extension of the known level scheme. The proton binding energy for91Nb was determined as (5167± 5) keV. Eleven γ transitions in90Zr, part of them new, from the competing reaction90Zr(p, p′ γ) were also observed.  相似文献   

7.
The collective moment of inertia ? band (2) of123Cs produced in the115In+12C reaction at 80 MeV has been measured by gamma-gamma energy correlation techniques. The variations of ? band (2) with the rotational frequency are compared to those of122Xe and analysed in the frame of a cranked Nilsson-Strutinsky model. We conclude that the addition of one proton to the triaxial (γ?30°)122Xe core gives a final prolate-type nucleus123Cs withγ?0° above a rotational frequency?0.55 MeV.  相似文献   

8.
High-spin states in 121Xe have been studied via the 109Ag (16O, p3n) 121Xe reaction at a beam energy of 80 MeV. Several rotational bands based on one- and three-quasiparticle excitations have been established. Among them, an unfavoured yrare rotational band with unfavoured signature has been newly identified. Received: 19 November 1998  相似文献   

9.
The lifetimes of several negative-parity states in 126,130Xe and 132Ba have been determined by means of the generalized centroid-shift method. The reactions 124,128Te(α, 2n) and 122Sn(13C, 3n) have been used. Following results were obtained: T1/2(2758 keV) = 1.3 ± 0.2 ns in 126Xe, T1/2 (2060 keV) = 0.20 ± 0.10 ns, T1/2 (2104 keV) = 0.50 ± 0.10 ns, T1/2 (2376 keV) = 0.30 ± 0.10 ns and T1/2 (2973 keV) = 4.6 ± 0.4 ns in 130Xe as well as T 1/2(2120 keV) = 0.40 ?0.10 +0.20 ns in 132Ba. A systematics of the B(E2; 7 1 ? ? 5 1 ? ) values in the N = 76 nuclei is presented. Electric dipole and quadrupole transition rates are discussed in terms of octupole and quadrupole collectivity. The structure of the 5 1 ? and 7 1 ? states is considered. Nuclear reactions: 124,128Te(α, 2n), E = 26 MeV, 122Sn (13C, 3n), E = 53 MeV; measured E{gg}, I{gg}, γ-r.f. Deduced T1/2, B(σL) in 126,130Xe and 132Ba. Ge detectors. Generalized centroid-shift analysis.  相似文献   

10.
Excited states of the 119Xe nucleus have been studied by using in-beam γ-ray spectroscopy with the 107Ag ( 16O, p3n) 119Xe fusion-evaporation reaction at a beam energy of 85 MeV. The level scheme of 119Xe has been derived from γ-γ coincidence and γ-γ angular correlation analyses. We have, for the first time, established the second negative-parity favored and unfavored states built on the 11/2- state, namely the yrare rotational bands in 119Xe. In contrast to the behavior of the yrast bands where the favored states are lying lower in energy, the yrare favored states were observed to lie above the unfavored band. Such a signature inversion in 119Xe is changed to be normal at I = 12?. Received: 8 January 2002 / Accepted: 18 April 2002  相似文献   

11.
Angular distributions of α-particles from the (t, α) reaction on 121Sb and 123Sb have been measured for incident tritons of 12 MeV. Levels up to excitation energies of 5.2 and 4.9 MeV in 120Sn and 122Sn, respectively, have been identified and analysed by the DWBA. Values of orbital angular momenta of the transferred protons have been assigned and spectroscopic factors deduced for all strongly excited levels. The extracted ground-state wave functions of the target nuclei have been compared with the calculated ones. A mixture of collective degrees of freedom is present in the low-lying states, weakly excited by the above very selective proton pick-up reaction. These states are populated by the pick-up of external protons (outer shells). At higher excitation energy (between 4 and 5 MeV) there are many strongly excited states populated by the proton pick-up from the Z = 50 proton core (inner shells); a predominantly 1p-1h character has been assigned to these states.  相似文献   

12.
Excited states of129Xe have been investigated through the126Te(α,n)129Xe reaction at the incident energy E=16MeV by means of in-beam gamma ray spectroscopy. Numerous levels below the excitation energy of 2.5MeV were found. Spin assignments were made from side feeding excitation functions. A new level at 274.2keV, which is suggested as spin 9/2 negtive parity bandhead, was observed for the first time.  相似文献   

13.
Excited states in127, 128Xe were populated in the reaction9Be+122Sn atE lab=38 MeV. The de-excitation of the isomeric states 7/2+ in127Xe and 8? in128Xe was studied using angular distribution and TDPAD methods on molten122Sn targets. The results are $$\begin{gathered} T_{1/2} (7/2^ + ) = 37 \pm 1 ns, g(7/2^ + ) = + 0.241 \pm 0.009 \hfill \\ T_{1/2} (8^ - ) = 83 \pm 2 ns, g(8^ - ) = - 0.036 \pm 0.009. \hfill \\ \end{gathered}$$ The experimentalg-factors suggest the main configurationsvg 7/2 andvh 11/2 g 7/2 for the isomeric states. Detailed analysis of the combined information fromg-factors and transition rates set stringent limits on the admixtures of the wave functions. The quasirotational bands built on the two-quasiparticle 6? and 10+ states are extended to higher spins, (14?) and (16+), respectively, and their structures are analyzed within the framework of the Interacting Boson Model.  相似文献   

14.
High-spin properties of even 118–122Xe isotopes have been studied in experiments when a 118 MeV 12C beam impinged on 114Cd and 116Cd targets. The γ-rays emitted following the reactions were detected by six NaI(Tl) counters. The coincidence events from the counters were sorted into a two-dimensional matrices, from which the energy-correlation spectra were extracted. From the energy correlation spectra the quantities of the collective moment of inertia I(2) are deduced and compared with data obtained for the same nuclei in previous experiments, as well as with results from theoretical studies.  相似文献   

15.
Excited states in odd–odd 126I have been studied via the heavy–ion induced fusion–evaporation reaction 122Sn(11B,5n2p) at beam energies of 55 and 60 MeV with beams provided by the HI–13 tandem accelerator of CIAE in Beijing.A level scheme consisting of 20 new γ transitions assigned to 126I is established.The assignment of the established level scheme to 126I is based on the observed coincidences between the newly identified γ–transitions and two previously known cascade γ transitions feeding the ground state of 126I, and supported by a cross measurement using the 124Sn(7lI,5n) reaction performed at UTTAC,Japan.The observed structures of 126I at high spins show typical properties of collective rotation in a deformed nucleus. their possible configurations are discussed briefly on the basis of knowledge from the neighboring nuclei.  相似文献   

16.
The average angular momenta of the 84Br, 132Sb, 133Te, and 135Xe fission fragments, produced as a result of 232Th and 238U photofission by bremmsstrahlung γ photons with an endpoint energy of 8.5 MeV, have been determined by measuring the isomeric yield ratios. The experimental isomeric yield ratios have been calculated taking into account the contribution from β decay of isobaric nuclei to the yields of isotopes studied.  相似文献   

17.
Coincidences have been detected between γ-rays and β-delayed protons emitted after the decay of very neutron-deficient nuclei. In the three cases studied the decay proceeds to the ground state with branches to the first excited (2+) state of the even daughter nucleus of (58±7) % (115Xe to 709 keV in 114Te), (14±3) % (117Xe to 679 keV in 116Te), and (50±10) % (181Hg to 158 keV in 180Pt). Upper limits of 2 and 6 % can be placed on the branches to the 4+ states of 114Te and 180Pt. For the cases of 115,117Xe, coincidences with annihilation radiation were also observed; the measured positon/proton ratio determines the difference QBp, between the energy available for electron capture and the proton separation energy for the daughter. For 115Xe the result is 6.20±0.13 MeV, for 117Xe 4.10±0.20 MeV.  相似文献   

18.
High spin states in 120Xe, populated via107Ag(16O, p2n) and108Pd(16O, 4n)reactions have been studied using γ-ray spectroscopic techniques. 21 new transitions have been added to extend the level scheme. Two S-bands are extended upto 26+ and 22+;these bands are found to cross the g. s band at hΩ=0. 39 and 0. 47 MeV. The band structures have been discussed within the framework of CSM.  相似文献   

19.
Theγ spectra emitted in the decay of122Xe and122I have been investigated using Ge(Li) detectors and a Ge(Li)-NaI coincidence apparatus. 14γ transitions with energies between 61.8 and 416.9 keV have been identified in the decay of122Xe, 44 transitions between 564.0 and 3,291.0 keV in the decay of122I. Level schemes having 7 excited levels for122I and 21 excited levels for122Te are proposed.  相似文献   

20.
Using microscopic interacting boson-fermion model formalism, the ground-band, β-band, γ-band and high spins states in even 116-122Xe isotopes are successfully described. It can explain the recent experimental result that collective structures may coexist with the single-particle states and subshell feature. It predictes the energies of 1+ states.  相似文献   

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