Structure of rotational bands in 253No

In-beam gamma-ray and conversion electron spectroscopic studies have been performed on the ²⁵³ No nucleus. A strongly coupled rotational band has been identified and the improved statistics allows an assignment of the band structure as built on the $\ensuremath 9/2^-[734]_{\nu}$ ground state. The results agree with previously known transition energies but disagree with the tentative structural assignments made in earlier work.     

Lifetime measurement in 195Po

The lifetime of the 17/2⁺ yrast state in ¹⁹⁵Po has been measured using the recoil distance Doppler-shift technique to be = 43(11) ps. The lifetime was extracted from the singles -ray spectra obtained by using the recoil-decay tagging method. The present work provides more information of the coupling schemes, shapes and configuration mixing in neutron-deficient odd-mass Po nuclei.     

Tensor glueball–meson mixing phenomenology

We study the Abelian Higgs model using an improved form of the action in the scalar sector. The subleading corrections are carefully analyzed and the connection between lattice and continuous parameters is worked out. The model is simulated for GeV and a remarkable improvement of the numerical performance is achieved for this value of the Higgs mass. Received: 29 December 1999 / Revised version: 3 April 2000 / Published online: 8 June 2000     

Role of fluorescent lamp phosphors in accidental radiation monitoring

The present paper reports studies on the applicability of fluorescent lamp phosphors in accidental radiation dosimetry. Strontium orthophosphate, which is used as one of the components in the fluorescent lamps, has been studied for its thermo-luminescence (TL) characteristics on exposure to different doses of beta irradiation. The analysis of the TL glow curve of the phosphor, with a well-defined glow peak at 553 K, and other experiments carried out have proved the utility of strontium orthophosphate as dosimetric material in the range of 10–200 Gy. It has been observed that the material satisfies most of the fundamental criteria for a good TLD-material. A fluorescent lamp developed with this material as TLD grade lamp phosphor is thus expected to serve twin purposes of providing illumination and monitoring the radiation released during a nuclear accident.     

Infrared absorbance cross-sections for dinitrogen pentoxide vapour

Laboratory measurements of the ν₁₂ absorption band of gaseous N₂O₅ have been made using Fourier transform infrared (FTIR) spectroscopy at seven different temperatures between 233 and 293 K. Integrated band strengths and absorbance cross-sections per molecule show no significant temperature dependence. Their average values are S_int = (4.09±0.17) × 10^-17 cm molecule ^-1 and σ_peak = (1.90±0.08) × 10^-18 cm² molecule^-1.     

Identification of excited states in the T(z) = 1 nucleus (110)Xe: evidence for enhanced collectivity near the N=Z=50 double shell closure

Gamma-ray transitions have been identified for the first time in the extremely neutron-deficient (N=Z+2) nucleus (110)Xe, and the energies of the three lowest excited states in the ground-state band have been deduced. The results establish a breaking of the normal trend of increasing first excited 2(+) and 4(+) level energies as a function of the decreasing neutron number as the N=50 major shell gap is approached for the neutron-deficient Xe isotopes. This unusual feature is suggested to be an effect of enhanced collectivity, possibly arising from isoscalar n-p interactions becoming increasingly important close to the N=Z line.     

Static charged spheres with anisotropic pressure in general relativity

We report a generalization of our earlier formalism [Pramana, 54, 663 (1998)] to obtain exact solutions of Einstein-Maxwell’s equations for static spheres filled with a charged fluid having anisotropic pressure and of null conductivity. Defining new variables: w=(4π/3)(ρ+ε)r ², u=4πξr ², v _r=4πp _r r ², v _⊥=4πp _⊥ r ²[ρ, ξ(=−(1/2)F ₁₄ F ¹⁴), p _r, p _⊥ being respectively the energy densities of matter and electrostatic fields, radial and transverse fluid pressures whereas ε denotes the eigenvalue of the conformal Weyl tensor and interpreted as the energy density of the free gravitational field], we have recast Einstein’s field equations into a form easy to integrate. Since the system is underdetermined we make the following assumptions to solve the field equations (i) u=v _r=(a ²/2κ)r ⁿ⁺², v _⊥=k ₁ v _r, w=k ₂ v _r; a ², n(>0), k ₁, k ₂ being constants with κ=((k ₁+2)/3+k ₂) and (ii) w+u=(b ²/2)r ⁿ⁺², u=v _r, v _⊥−v _r=k, with b and k as constants. In both cases the field equations are integrated completely. The first solution is regular in the metric as well as physical variables for all values of n>0. Even though the second solution contains terms like k/r ² since Q(0)=0 it is argued that the pressure anisotropy, caused by the electric flux near the centre, can be made to vanish reducing it to the generalized Cooperstock-de la Cruz solution given in [14]. The interior solutions are shown to match with the exterior Reissner-Nordstrom solution over a fixed boundary. Dedicated to Prof. F A E Pirani.     

A short range many-body potential for modelling bcc metals

The problem considered is the fitting of a many-body interaction potential to bulk crystal data. A parameterisation of the potential is assumed which is based on physical considerations. The free parameters are determined by using global optimization to perform a least squares fit, to a large number of crystal properties. This has been achieved for body centered cubic (bcc) materials. The approach adopted here fits the bcc crystal structure, as the preferred minimum energy configuration for tungsten, and also fits the dimer energetics and the elastic properties of crystalline tungsten.     

The Frobenius complexity of Hibi rings

We study the Frobenius complexity of Hibi rings over fields of characteristic $p>0$. In particular, for a certain class of Hibi rings (which we call ${\omega }^{(?1)}$-level), we compute the limit of the Frobenius complexity as $p\to \infty$.