Shape-driving effect of the proton 1/2[541] band in 171Ta

High-spin states in ¹⁷¹Ta were populated through the heavy-ion fusion-evaporation reaction ¹⁵⁷Gd (¹⁹F, 5n)¹⁷¹Ta at 105MeV beam energy. Lifetimes of the levels of the πh_9/21/2[541] band have been measured by using the Doppler shift attenuation method. The transition quadrupole moments ( Q_t) and the quadrupole deformation (β₂) have been extracted. Both β₂ and Q_t values decrease slightly with increasing rotational frequency. The average β₂ value of 0.26 is 18% larger than that of the πh_11/2 9/2[514] band. Total Routhian Surface calculations have been performed with the non-axial deformed Woods-Saxon potential and the predicted values of the quadrupole deformation β₂ are in good agreement with that deduced from our lifetime measurement. The shape-driving effect is discussed.     

Delayed crossing in the \pi h_{9/2} 1/2-[541] band of 173 Lu

High-spin states in the odd-proton nucleus ¹⁷³Lu have been populated in a ¹⁷⁰Er(⁷Li,4n) reaction and the emitted -radiation was detected with the GASP array. The favoured and unfavoured sequences of the band have been considerably extended. The favoured sequence does not show any indication of a band crossing up to a rotational frequency of 0.45 MeV. This is the largest crossing frequency ever observed for 1/2^- [541] bands of odd-proton nuclei with and . Previous Cranked Shell Model (CSM) calculations underestimate the crossing frequency by 100 keV.Received: 19 May 2003, Published online: 11 November 2003PACS: 21.10.-k Properties of nuclei; nuclear energy levels - 21.10.Re Collective levels - 23.20.Lv transitions and level energies - 27.70. + q      

Proton Orbital [541]1/2 and Backbending in 178W

The microscopic mechanism of nine experimentally observed bands in ^178W is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions. The experimental results, including the moments of inertia and angular momentum alignments of nine bands in ^178W, are reproduced well by the particle-number conserving calculations, in which no free parameter is involved. Calculations demonstrate that occurrence of sharp backbending comes mainly from the contribution of high-j intruder orbitals vi13/2 or πh11/2 and their interference effect with orbitals near the Fermi surface. Theω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are analyzed.     

Proton Orbital [541]1/2 and Backbending in 178W

The microscopic mechanism of nine experimentally observed bands in ¹⁷⁸W is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions. The experimental results, including the moments of inertia and angular momentum alignments of nine bands in ¹⁷⁸W, are reproduced well by the particle-number conserving calculations, in which no free parameter is involved. Calculations demonstrate that occurrence of sharp backbending comes mainly from the contribution of high-j intruder orbitals νi13/2 or πh11/2 and their interference effect with orbitals near the Fermi surface. The ω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are analyzed.     

Magnetic moment of the 5/2−1/2[541] ground state of 14h 185Ir

The magnetic and electric hyperfine splitting frequencies ¦gμ _N B _HF/h¦ ande ² qQ/h of the 5/2^?1/2[541] ground state of 14h ¹⁸⁵Ir in Ni were measured with nuclear magnetic resonance on oriented nuclei to be 360.8(7) MHz and +6.7(2.0) MHz, respectively. The ground state magnetic dipole moment and electric quadrupole moment of¹⁸⁵Ir are deduced to be ¦μ¦=2.601 (14)μ _N andQ=?1.9(5)b, taking values for the hyperfine field and electric field gradient of B_HF=?454.9 (2.3) kG and eq=?0.151(4) × 10¹⁷ V/cm², respectively. The negative quadrupole moment is in agreement with nuclear-orientation data and proves again theI ^π K=5/2^? 1/2 ground state configuration.     

p-n相互作用对1/2~-[541]带带交叉频率延迟的影响

通过转动框架下的经验近似,提取了A=160区4个核的剩余p n相互作用对1/2-[541]带的带交叉频率延迟的影响.结果表明,对于奇Z核中1/2-[541]带的带交叉频率的延迟,剩余p n相互作用的影响大约占二分之一左右,表明剩余p n相互作用在其中起着很重要的作用.We estimated the effect of residual p-n interaction on the crossing frequency delay of the 1/2~(-)\ band of four odd-Z nuclei through the empirical method. The result shows that about half of the shift in crossing frequency in the 1/2~-\ band is the effect of residual p-n interaction. The residual p-n interaction plays a very important role in the crossing frequency delay of the 1/2~(-)\ band.     

Anomalous frequency shift in the photoassociation spectrum of a Bose-Einstein condensate

We theoretically investigate the effect of anomalous quantum correlations on the light-induced frequency shift in the photoassociation spectrum of a Bose-Einstein condensate. Anomalous quantum correlations arise because, although formed from a pair of zero-momentum condensate atoms, a condensate molecule need not dissociate back to the atomic condensate, but may just as well form a noncondensate atom pair with equal and opposite momentum, i.e., due to rogue photodissociation. The uncorrelated frequency shift of the photoassociation spectrum is to the red and linearly dependent on the laser intensity I. In contrast, anomalous correlations due to rogue dissociation lead to a blueshifted photoassociation spectrum. For sufficiently low light intensities, the rogue blueshift is dominant and proportional to sqrt[I].     

The rotational bands 12+[411]and 12−[541]in 175Lu

In a study of the γ-radiation emitted in the reaction ¹⁷⁶Yb(p, 2n) excited states of the nucleus ¹⁷⁵Lu up to spin I = $\text{13}\text{2}$ have been investigated. The main results concern the rotational bands $\text{1}\text{2}$⁺ [411]and $\text{1}\text{2}$^? [541]with the corresponding band heads found at 626.60 and 370.88 keV, respectively. The half-life of the $\text{1}\text{2}$⁺[411] level has been determined to be $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 10.7±0.5}\text{ns}$. Furthermore, the band heads $\text{3}\text{2}$^?[532]and $\text{3}\text{2}{}^{\mathrm{+}}$[411]are proposed at energies of 999.0 and 1150.8 keV, respectively. Experimental E1 transition probabilities between both $\text{K =}\text{1}\text{2}$ bands are compared with calculations including the Coriolis and pairing effects, as well as theoretically deduced quadrupole deformation parameters.     

Loss of alignment gain in the πh 9/2[541 1/2−] ⊗ (νi 13/2)2 band in 167Tm and neighbouring odd-Z N = 98 nuclei

Theπh_9/2[541 1/2^?] band in ¹⁶⁷Tm has been studied through the ¹²⁴Sn(⁴⁸Ca, p4n)¹⁶⁷Tm reaction at E _beam = 210 MeV. The favoured signature of the πh_9/2[541 1/2^?] band is observed to spin 61/2h?. A remarkable small gain in aligned angular momentum at the AB-band crossing has been found. The crossing frequency and the gain in aligned angular momentum for ¹⁶⁷Tm are compared with data for the N = 98 isotones of Lu, Ta and Re, and contrasted with Cranked Shell Model predictions, based on frequency diabatic configurations. Large deviations are found for the gain in aligned angular momentum.     

Properties of the 3/2~-[521] band in the odd-N rare-earth nuclei

High-spin states in 161Er have been studied experimentally via the 150Nd(16O, 5n) reaction at a beam energy of 86 MeV. Three rotational bands built on the 5/2+[642], 3/2-[521], and 11/2-[505] configurations have been extended up to high-spin states, and particularly, the α = -1/2 branch of the ground state 3/2-[521] band has been revised significantly. It is found that signature inversion occurs in the 3/2-[521] band after the band crossing in 161Er. The systematics of the signature inversion associated wit...     

Evidence for the existence of the [2 0 2]3/2 deformed band in mirror nuclei 25Mg and 25Al

After 50 years of its prediction, the highest-lying [2 0 2]3/2 orbit among the six Nilsson single-particle orbits originating from the sd shells in prolately deformed nuclei and the rotational band on this orbit were identified. The band members were observed in 25Al at excitation energies of 6-7.5 MeV in a high-resolution 25Mg(3He,t) charge-exchange reaction at 0 degrees having a strong selectivity for Gamow-Teller transitions. In the comparison with the analogous M1 transitions in 25Mg, the J(pi)=3/2(+) bandhead state and the excited 5/2(+) and 7/2(+) members were clearly assigned.     

Anomalous temperature dependence of the band gap in AgGaSe2 and AgInSe2

The lowest band gaps of AgGaSe₂ and AgInSe₂ single crystals in the temperature range from 90 to 300 K were determined from photoconductivity measurements. Below (above ≈ 120 K in AgInSe₂ and ≈ 125 K in AgGaSe₂ the temperature coefficient of the band gap is +5 × 10⁻⁴ eV/K (−1.5 × 10⁻⁴ eV/K) and +1.1 × 10⁻⁴ eV/K (−4.28 × 10⁻⁴ eV/K), respectively. The positive value is explained with the lattice dilation effect being the dominant mechanism for the band gap variation at the temperatures less than ≈ 120–125 K.     

Heat capacity of the PbFe1/2Ta1/2O3 perovskite-like compound

Physics of the Solid State - The heat capacity C p(T) of the complex perovskite PbFe1/2Ta1/2O3 has been studied using adiabatic calorimetry in the temperature range 150–370 K. Three diffuse...     

Anomalous magnetoresistance in 1T-TaS2

Transverse magnetoresistance of 1T-TaS₂ was measured in magnetic fields up to 100 kOe in the semiconductive region corresponding to the commensurate charge density wave (CDW) state.     

Anomalous magnetooptical behaviour of Pb1−xMnxTe in the interband frequency range

Magnetooptical interband transitions were investigated in Pb_1?xMn_xTe (0.01<x<0.02) in Faraday and Voigt configuration. The observed transition energies do not extrapolate for H→O to one but to two energy gaps. From a comparison of the selection rules in both geometries, this splitting originates mainly from a non-vanishing spin splitting in the completedly filled valence band. Neither the H→O, nor the finite field data can be reconciled with the measured magnetisation data on the basis of existing theories of semimagnetism.