Systematic decay studies of even-even 132−138132-138^Nd, 144−158144-158^Gd, 176−196176-196^Hg and 192−198192-198^Pb isotopes

The alpha and cluster decay properties of the $132-138$^Nd, $144-158$^Gd, $176-196$^Hg and $192-198$^Pb even-even isotopes in the two mass regions A = 130-158 and A = 180-198 are analysed using the Coulomb and Proximity Potential Model. On examining the clusters at corresponding points in the cold valleys (points with same A_2) of the various isotopes of a particular nucleus we find that at certain mass numbers of the parent nuclei, the clusters emitted are getting shifted to the next lower atomic number. It is interesting to see that the change in clusters appears at those isotopes where a change in shape is occurring correspondingly. Such a change of clusters with shape change is studied for the first time in cluster decay. The alpha decay half lives of these nuclei are computed and these are compared with the available experimental alpha decay data. It is seen that the two are in good agreement. On making a comparison of the alpha half lives of the normal deformed and super deformed nuclei, it can be seen that the normal deformed $132$^Nd, $176-188$^Hg and $192$^Pb nuclei are found to be better alpha emitters than the super deformed (in excited state) $134,136$^Nd, $190-196$^Hg and $194$^Pb nuclei. The cluster decay studies reveal that as the atomic number of the parent nuclei increases the N \neq Z cluster emissions become equally or more probable than the N=Z emissions. On the whole the alpha and cluster emissions are more probable from the parents in the heavier mass region (A=180-198) than from the parents in the lighter mass region (A= 130-158). The effect of quadrupole ({\beta}_2) and hexadecapole ({\beta}_4) deformations of parent and fragments on half life times are also studied.Comment: 42 pages,19 figure

Systematic study of heavy cluster emission from {210-226}^Ra isotopes

The half lives for various clusters lying in the cold reaction valleys of {210-226}^Ra isotopes are computed using our Coulomb and proximity potential model (CPPM). The computed half lives of 4^He and 14^C clusters from {210-226}^Ra isotopes are in good agreement with experimental data. Half lives are also computed using the Universal formula for cluster decay (UNIV) of Poenaru et al., and are found to be in agreement with CPPM values. Our study reveals the role of doubly magic 208^Pb daughter in cluster decay process. Geiger - Nuttall plots for all clusters up to 62^Fe are studied and are found to be linear with different slopes and intercepts. {12,14}^C emission from 220^Ra; 14^C emission from {222,224}^Ra; 14^C and 20^O emission from 226^Ra are found to be most favourable for measurement and this observation will serve as a guide to the future experiments.Comment: 22 pages, 6 figures; Nuclear Physics A (2012

Fine structure in the {\alpha}-decay of odd-even nuclei

Systematic study on {\alpha}-decay fine structure is presented for the first time in the case of odd-even nuclei in the range 83 \leq Z \leq 101. The model used for the study is the recently proposed Coulomb and proximity potential model for deformed nuclei (CPPMDN), which employs deformed Coulomb potential, deformed two term proximity potential and centrifugal potential. The computed partial half lives, total half lives and branching ratios are compared with experimental data and are in good agreement. The standard deviation of partial half-life is 1.08 and that for branching ratio is 1.21. Our formalism is also successful in predicting angular momentum hindered and structure hindered transitions. The present study reveals that CPPMDN is a unified theory which is successful in explaining alpha decay from ground and isomeric state; and alpha fine structure of even-even, even-odd and odd-even nuclei. Our study relights that the differences in the parent and daughter surfaces or the changes in the deformation parameters as well as the shell structure of the parent and daughter nuclei, influences the alpha decay probability.Comment: 35 pages, 5 figure

Hybrid Dissemination: Adding Determinism to Probabilistic Multicasting in Large-Scale P2P Systems

Abstract. Epidemic protocols have demonstrated remarkable scalability and robustness in disseminating information on internet-scale, dynamic P2P systems. However, popular instances of such protocols suffer from a number of significant drawbacks, such as increased message overhead in push-based systems, or low dissemination speed in pull-based ones. In this paper we study push-based epidemic dissemination algorithms, in terms of hit ratio, communication overhead, dissemination speed, and resilience to failures and node churn. We devise a hybrid push-based dissemination algorithm, combining probabilistic with deterministic properties, which limits message overhead to an order of magnitude lower than that of the purely probabilistic dissemination model, while retaining strong probabilistic guarantees for complete dissemination of messages. Our extensive experimentation shows that our proposed algorithm outperforms that model both in static and dynamic network scenarios, as well as in the face of large-scale catastrophic failures. Moreover, the proposed algorithm distributes the dissemination load uniformly on all participating nodes. Keywords: Epidemic/Gossip protocols, Information Dissemination, Peer-to-Peer

Learning Behavioural Context

The original publication is available at www.springerlink.co

The Energy of Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics

According to the Einstein, Weinberg, and M{\o}ller energy-momentum complexes, we evaluate the energy distribution of the singularity-free solution of the Einstein field equations coupled to a suitable nonlinear electrodynamics suggested by Ay\'{o}n-Beato and Garc\'{i}a. The results show that the energy associated with the definitions of Einstein and Weinberg are the same, but M{\o}ller not. Using the power series expansion, we find out that the first two terms in the expression are the same as the energy distributions of the Reissner-Nordstr\"{o}m solution, and the third term could be used to survey the factualness between numerous solutions of the Einstein field eqautions coupled to a nonlinear electrodynamics.Comment: 11 page

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter