119117378
Hadron energy response of the Iron Calorimeter detector at the India-based Neutrino Observatory
The results of a Monte Carlo simulation study of the hadron energy response for the magnetized Iron CALorimeter detector, ICAL, proposed to be located at the India-based Neutrino Observatory (INO) is presented. Using a GEANT4 modeling of the detector ICAL, interactions of atmospheric neutrinos with target nuclei are simulated. The detector response to hadrons propagating through it is investigated using the hadron hit multiplicity in the active detector elements. The detector response to charged pions of fixed energy is studied first, followed by the average response to the hadrons produced in atmospheric neutrino interactions using events simulated with the NUANCE event generator. The shape of the hit distribution is observed to fit the Vavilov distribution, which reduces to a Gaussian at high energies. In terms of the parameters of this distribution, we present the hadron energy resolution as a function of hadron energy, and the calibration of hadron energy as a function of the hit multiplicity. The energy resolution for hadrons is found to be in the range 85% (for 1 GeV) – 36% (for 15 GeV).
119298119
Unitarity constraints on trimaximal mixing
When the neutrino mass eigenstate {nu}{sub 2} is trimaximally mixed, the mixing matrix is called trimaximal. The middle column of the trimaximal mixing matrix is identical to tribimaximal mixing and the other two columns are subject to unitarity constraints. This corresponds to a mixing matrix with four independent parameters in the most general case. Apart from the two Majorana phases, the mixing matrix has only one free parameter in the CP conserving limit. Trimaximality results in interesting interplay between mixing angles and CP violation. A notion of maximal CP violation naturally emerges here: CP violation is maximal for maximal 2-3 mixing. Similarly, there is a natural constraint on the deviation from maximal 2-3 mixing which takes its maximal value in the CP conserving limit.
16931053
CP-odd weak basis invariants and texture zeros
We construct the CP-odd weak basis invariants from the neutrino mass matrix in a weak basis, in which the charged lepton mass matrix is diagonal, and find the necessary and sufficient conditions for CP conservation. We study the interrelationships between different CP-odd weak basis invariants to examine their implications for the Dirac- and Majorana-type CP violating phases for the phenomenologically allowed Frampton-Glashow-Marfatia texture zero structures of the neutrino mass matrix.
15773149
CONSTRAINTS ON THE NEUTRINO PARAMETERS FROM THE "RISE-UP" IN THE BORON NEUTRINO SPECTRUM AT LOW ENERGIES
The rise-up in boron neutrino spectrum at low energies has been studied within the framework of "pure LMA" scenario. Indirect bounds on the spectral "upturn" have been obtained from the available solar neutrino data. These bounds have been used to demonstrate the efficacy of the precision measurements of the "upturn" for further constraining the neutrino parameter space allowed by SNO salt phase data. The sterile neutrino flux has been constrained in the light of the recent 766.3 Ty KamLAND spectral data.
2063566
Phenomenology of Two-Texture Zero Neutrino Mass Matrices
The generic predictions of two-texture zero neutrino mass matrices in the flavor basis have been examined especially in relation to the degeneracies between mass matrices within a class and interesting constraints on the neutrino parameters have been obtained. It is shown that the knowledge of the octant of ${\ensuremath{\theta}}_{23}$, the sign of $\mathrm{cos}﻿\ensuremath{\delta}$, and neutrino mass hierarchy can be used to lift these degeneracies.
119100875
Symmetry based parametrizations of the lepton mixing matrix
There are many mixing schemes based upon flavor symmetries that predict a vanishing $\theta_{13}$. These mixing schemes need corrections or modifications to account for recent experimental measurements of non-zero $\theta_{13}$. We propose new parameterizations for the lepton mixing matrix to quantify the minimal modifications needed in these mixing schemes. The parameterizations can be factorized in two parts: $U_{0}(a,b)$ and $R(\theta,\phi)$. The first factor can be viewed as a zeroth order mixing matrix coming from some flavor symmetry. It reproduces the popular mixing schemes based upon flavor symmetries for suitable values of $a$ and $b$. The second factor can be interpreted as a minimal modification to the mixing matrix and is responsible for non zero $\theta_{13}$, non-maximal $\theta_{23}$ and CP violation. We also find the experimentally allowed parameter space for the parameters $a$ and $b$ and compare it with the symmetry based values for these parameters.
118406564
Effect of the symmetry energy on nuclear stopping and its relation to the production of light charged fragments
We present a complete systematics (excitation function, impact parameter, system size, isospin asymmetry, and equations of state dependences) of global stopping and fragment production for heavy-ion reactions in the energy range between 50 and 1000 MeV/nucleon in the presence of symmetry energy and an isospin-dependent cross section. It is observed that the degree of stopping depends weakly on the symmetry energy and strongly on the isospin-dependent cross section. However, the symmetry energy and isospin-dependent cross section has an effect of the order of more than 10% on the emission of light charged particles (LCP's). It means that nuclear stopping and LCP's can be used as a tool to get the information of an isospin-dependent cross section. Interestingly, the LCP's emission in the presence of symmetry energy is found to be highly correlated with the global stopping.
120886307
Anisotropic Bianchi type-I models with constant deceleration parameter in general relativity
Abstract
A special law of variation for Hubble’s parameter is presented in a spatially homogeneous and anisotropic Bianchi type-I space-time that yields a constant value of deceleration parameter. Using the law of variation for Hubble’s parameter, exact solutions of Einstein’s field equations are obtained for Bianchi-I space-time filled with perfect fluid in two different cases where the universe exhibits power-law and exponential expansion. It is found that the solutions are consistent with the recent observations of type Ia supernovae. A detailed study of physical and kinematical properties of the models is carried out.

118430195
Clustering GCG: a viable option for unified dark matter-dark energy?
We study the clustering Generalized Chaplygin Gas (GCG) as a possible candidate for dark matter-dark energy unification. The vanishing speed of sound 0c{sub s}{sup 2} = ) for the GCG fluid can be obtained by incorporating higher derivative operator in the original K-essence Lagrangian. The evolution of the density fluctuations in the GCG+Baryon fluid is studied in the linear regime. The observational constraints on the model are obtained using latest data from SNIa, H(z), BAO and also for the fσ{sub 8} measurements. The matter power spectra for the allowed parameter values are well behaved without any unphysical features.
14314222
A Large area plastic scintillator detector array for fast neutron measurements
Abstract A large area plastic scintillator detector array ( ∼ 1 × 1 m 2 ) has been set up for fast neutron spectroscopy at the BARC-TIFR Pelletron laboratory, Mumbai. The energy, time and position response has been measured for electrons using radioactive sources and for monoenergetic neutrons using the 7 Li ( p , n 1 ) 7 Be * ( 0.429 MeV ) reaction at proton energies between 6.3 and 19 MeV. A Monte Carlo simulation of the energy dependent efficiency of the array for neutron detection is in agreement with the 7 Li ( p , n 1 ) measurements. The array has been used to measure the neutron spectrum, in the energy range of 4–12 MeV, in the reaction C 12 + Nb 93 at E ( C 12 ) = 40 MeV . This is in reasonable agreement with a statistical model calculation.
62827271
To Study the effects of isospin cross section on mass asymmetric nuclear reactions
We studied the effect of cross section on mass asymmetric systems. The mass asymmetry of a reaction can be defined by the asymmetry parameter {\eta} = |(AT - AP)/(AT + AP)|; [1] where AT and AP are the masses of the target and projectile, respectively. The {\eta} = 0 corresponds to the symmetric reactions, whereas non-zero values of {\eta} define different asymmetries of a reaction. Reactions include 208Pb82 + 208Pb82 having {\eta} = 0, 40Ca20 + 208Pb82 having {\eta} = 0.6 and 12C6 + 197Au79 having {\eta} = 0.8 This work has been carried out within the frame work of isospin dependent quantum molecular dynamics (IQMD) model.