A new high-spin isomer in 145Eu

In ¹⁴⁵Eu a high-spin isomer with E _level = 8528 keV and T _1/2 = (3.7 ± 0.4) ns has been observed. The data were obtained by in-beam γ-ray spectroscopy using the reaction ¹²²Sn(²⁷Al,4n)¹⁴⁵Eu at 127 MeV performed at the NORD-BALL spectrometer in Roskilde.     

A new high-spin isomer in 145Sm

A new high-spin isomer in ¹⁴⁵Sm was observed by in-beam γ-ray spectroscopy with the reaction ¹²²Sn(²⁷Al,3np) at 127 MeV performed at the Nordball multi-detector array in Roskilde. The excitation energy of the isomer was determined to be E _x= 11147 keV, and using the generalized centroid-shift method its half-life was found to be T _1/2= (7.4 ± 1.0) ns. Received: 23 October 1998     

Lifetime of a new high-spin isomer in 150 Dy

A new high-spin isomer in ¹⁵⁰Dy has been observed at an excitation energy of 10.3 MeV by combining the inverse-kinematic reaction induced by a pulsed beam of ¹³²Xe and the -ray recoil-shadow technique. The half-life of this isomeric state has been determined to be ns using the conventional centroid-shift method with the ¹⁴¹Pr(¹⁶O, p6n)¹⁵⁰Dy reaction at 165 MeV. The mechanism producing high-spin isomers in N = 83,84 isotones is qualitatively discussed in terms of the difference of the neutron particle-hole configuration between the high-spin isomer and the lower-lying state.Received: 3 September 2003, Revised: 8 October 2003, Published online: 5 January 2004PACS: 21.10.Tg Lifetimes - 23.20.Lv transitions and level energies - 27.70. + q T. Fukuchi: Present address: Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.W. Sato: Present address: Graduate School of Science, Osaka University, 1-1 Machikaneyamacho, Toyonaka, Osaka 560-0043, Japan.     

A high-spin isomer in 204Bi

By making use of heavy-ion and α-particle induced reactions an isomeric state has been found in ²⁰⁴Bi, with a half-life of $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 1.07 ± 0.03}\text{ms}$ and the quantum characteristics I^π = 16⁺. The four-quasiparticle configuration $\text{ν(}\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{?2}}\text{ν(}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)}{}^1\text{π(}\text{h}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{)}{}^1$ has been ascribed to this state.     

A new sequence of high-spin states built on the 17/2+ isomer in85Kr

High-spin states in⁸⁵Kr have been studied via in-beam spectroscopy by bombarding a⁸²Se target with 32 MeV⁷Li ions. Since⁸⁵Kr is only formed with a small relative cross section proton-— coincidence techniques have been applied to enhance the rays of⁸⁵Kr, even with respect to those of⁸⁶Kr, in the measurements. A new sequence of high-spin states with excitation energies up to 4.8 MeV and tentative spins up to (23/2) has been established on top of the 17/2⁺ s isomer. A tentative assignment of the configurationvg ₉ ^2/–1 (g _9/2 p ₃ ^2/–1 orf ₅ ^2/–1 ) to the new levels is proposed.Supported by Deutsche Forschungsgemeinschaft     

Revised spin-parity assignment and a new interpretation of the high-spin isomer in 151Er

The high-spin isomer in ¹⁵¹Er ( E _x = 10.3 MeV, T _1/2 = 420 ns) has been studied by the ¹¹⁶Sn ( ⁴⁰Ar , 5n) ¹⁵¹Er reaction at 197MeV. From the $ \gamma \gamma$ coincidence relations, a new transition with an energy of 1514keV was found. This finding requires the revision of the spin-parity assignment from previous 67/2^- to 61/2⁺ or 65/2^- . The 61/2⁺ assignment is the one which was predicted by the deformed independent particle model as an isomer with a large oblate deformation ( $ \beta$ = - 0.17) of the $\ensuremath[\nu(f_{7/2}h_{9/2} i_{13/2}) \pi(h^4_{11/2})]_{61/2^+}$ configuration. The isomerism may be attributed to the sudden shape change of the isomer from the nearly spherical shape of the lower-spin yrast states to the oblate shape.     

Systematics of high-spin isomers in N = 83 isotones and a high-spin isomer beam

Isomers in N = 83 isotones of Z = 60-66, were studied systematically. Their spins and parities are 49/2⁺ and 27⁺ for odd and odd-odd nuclei, respectively. Nearly constant excitation energies of these isomers indicated a decrease of a Z = 64 shell gap energy as Z decreases from 64 to 60 within the framework of a deformed independent-particle model (DIPM). Their configurations are [ν(f _7/2 h _9/2 i _13/2),π(h _11/2)²]_49/2+ and [ν(f _7/2 h _9/2 i _13/2),π(h _11/2)²(d _5/2)^-1]₂₇₊ for odd and odd-odd nuclei, respectively. The shape of the yrast states changes suddenly at spin 49/2(odd) and 27(odd-odd) from a near spherical to an oblate shape. Transitions from isomers are highly hindered because of the shape changes. They may be categorized to be shape isomers. The development of a secondary beam produced by using these high-spin isomers is also described. Received: 1 May 2001 / Accepted: 4 December 2001     

A new isomer in205Po

A new isomer withT _1/2=58±2 ms has been observed in²⁰⁵Po. We propose the assignmentsI ^π = 19/2^? and an excitation energyE _x =1461 keV.     

Lifetimes of high-spin levels in39Ar

The high-spin states in³⁹Ar at 2651, 3992, 4543, and 5536 keV were excited in oxygen-induced fusion-evaporation reactions. Mean lifetimes ofτ _m =1.0±0.2, 1.2±0.3, 1.6±0.3, and <1 ps were determined for these levels, respectively, by means of the recoil distance Doppler shift technique. The transition rates are discussed in terms of the Bansal-French weak-coupling model.     

A new isomer in 125La

Levels in ¹²⁵La have been studied via #⁺/EC decay of on-line mass-separated ¹²⁵Ce using the HIGISOL technique. A new (390 - 40) ms isomer is definitely attributed to ¹²⁵La by conversion electron measurements of the 107 keV E3 isomeric transition.     

New investigation of the decay of the high-spin isomer in 151Er

The decay of the T _1/2 = 420 ns isomer in ¹⁵¹Er has been reinvestigated. The multipolarities of the decaying transitions have been established by measuring the electron conversion coefficients. An I ^π = 67/2⁻ assignment is proposed for this isomer with a π[h ₁₁^2/4 d ₃^2/1 d ₅^2/−1]⊗ν[f _7/2 h _9/2 h ₁₁^2/−1] configuration.     

Connection between backbending and high-spin isomer decay in 179W

A new 710 ns isomer in ¹⁷⁹W is found to decay directly into backbending region of the $\text{7}\text{2}{}^{\mathrm{-}}\text{(514)}$ gorund-state band. The $\text{i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ band is observed up to spin $\text{41}\text{2}$ and shows no evidence for backbending at core rotational frequencies, where the effect is observed in the ¹⁷⁹W and ¹⁸⁰W ground-state bands.     

A new high spin isomer in 146Eu

High spin states of ¹⁴⁶Eu were studied by in-beam gamma ray spectroscopic techniques using ¹⁴⁰Ce(¹⁰B,4n)¹⁴⁶Eu and ¹³⁹La(¹³C,6n)¹⁴⁶Eu reactions. The level scheme was established up to 10MeV. A new high spin isomer with 10ns half life was found. Configurations of yrast states were understood by a weak coupling of f_7/2 neutron to those of ¹⁴⁵Eu. Received: 2 November 1999     

Mass measurements and implications for the energy of the high-spin isomer in 94Ag

Nuclides in the vicinity of 94Ag have been studied with the Penning trap mass spectrometer JYFLTRAP at the Ion-Guide Isotope Separator On-Line. The masses of the two-proton-decay daughter 92Rh and the beta-decay daughter 94Pd of the high-spin isomer in 94Ag have been measured, and the masses of 93Pd and 94Ag have been deduced. When combined with the data from the one-proton- or two-proton-decay experiments, the results lead to contradictory mass excess values for the high-spin isomer in 94Ag, -46 370(170) or -44 970(100) keV, corresponding to excitation energies of 6960(400) or 8360(370) keV, respectively.     

Observation of proton radioactivity of the (21+) high-spin isomer in 94Ag

We have observed direct one-proton decay of the (21+) isomer in the N=Z nuclide 94Ag into high-spin states in 93Pd by detecting protons in coincidence with gamma-gamma correlations and applying gamma gates based on known 93Pd levels. Two decay branches have been identified, with proton energies of 0.79(3) and 1.01(3) MeV and branching ratios of 1.9(5)% and 2.2(4)%, respectively. The corresponding partial half-life values are 21(6) and 18(4) s. The Q value of the direct proton decay of the (21+) isomer was found to be 5.78(3) MeV. The very small reduced widths of the observed proton decays might reflect dominating collective configurations in the (21+) isomer, and the fine structure of the proton spectrum might indicate a strong deformation of this state.     

一种新的C32异构体

我们构造出一种新的类笼形C32异构体, 不包含五边形和六边形结构,具有D2h对称性.采用密度泛函理论DFT的rb3lyp方法在6-31G(d)基组水平上进行了相关计算 .计算结果表明它是一种稳定的构型.     

β delayed proton emission from a long-lived high-spin isomer in 95Pd

A long-lived high-spin isometric state in ⁹⁵Pd with a half-life of 14 ± 1s and with $\text{J}{}^{\mathrm{\pi }}\text{≈}\text{21}\text{2}{}^{\mathrm{+}}$ has been identified. It has been found that this state is a β delayed proton precursor. A decay scheme of ⁹⁵Pd has been derived.