Leak Test of Resistive Plate Chamber Gap by Monitoring Absolute Pressure

The India-based Neutrino Observatory Project (INO) is a proposed underground high energy physics experiment at Theni, India to study the neutrino oscillation parameters using atmospheric neutrinos. The 50 kton magnetised INO-ICAL detector will require approximately 30,000 of 2m$\times$2m Resistive Plate Chambers (RPC) as sensitive detectors and proposed to operate for about 20 years. For success of the experiment, each of the RPCs has to function without showing any significant aging during the period of operation. Hence, various tests including a proper leak test are performed during and after production. The methods of leak rate calculation using conventional manometer are valid only when both the volume of the test subject and ambient pressure are kept constant. But both these quantities for a RPC gas gap depend widely on the ambient pressure and temperature. A proper quantitative estimation of the leak rate cannot be acquired from such pressure measurements. By monitoring the absolute pressures, both outside and inside of an RPC, along with the temperature, its leakage rate can be estimated. During the test period, the supporting button spacers inside an RPC may get detached due to manufacturing defect. This effect also needs to be detected.Comment: 15 page

Compositional analysis of laser produced plasma plume in front and back ablation geometries

Composition analysis of LiF-C thin film for neutral and ionic contributions in Front Ablation (FA) and Back Ablation (BA) geometries in vacuum and 2\times10-1 mbar argon has been done. Temporal evolution of ionic to neutral ratio and neutral abundance for both the geometries has been estimated. For neutral abundance, two approaches viz Atomic Data and Analysis Structure (ADAS) analysis as well as integrated intensity ratio of Li I 670.1 nm and Li I 610.3 nm lines assuming LTE conditions are explored. The present attempt will be interesting from the view point of understanding the evolution of plasma composition in various geometries/configurations of laser ablation which has important implications in various applications e.g. pulsed laser deposition and laser cleaning.Comment: This manuscript is of 17 pages and has 12 figure

Constraining the symmetry energy content of nuclear matter from nuclear masses: a covariance analysis

Elements of nuclear symmetry energy evaluated from different energy density functionals parametrized by fitting selective bulk properties of few representative nuclei are seen to vary widely. Those obtained from experimental data on nuclear masses across the periodic table, however, show that they are better constrained. A possible direction in reconciling this paradox may be gleaned from comparison of results obtained from use of the binding energies in the fitting protocol within a microscopic model with two sets of nuclei, one a representative standard set and another where very highly asymmetric nuclei are additionally included. A covariance analysis reveals that the additional fitting protocol reduces the uncertainties in the nuclear symmetry energy coefficient, its slope parameter as well as the neutron-skin thickness in $^{208}$Pb nucleus by $\sim 50\%$. The central values of these entities are also seen to be slightly reduced.Comment: 6 pages, 2 figures, Accepted in Physical Review

Sensitivity of elements of the symmetry energy of nuclear matter to the properties of neutron-rich systems

The sensitivity of nuclear symmetry energy elements at the saturation density to the binding energies of ultra neutron-rich nuclei (neutron to proton ratio $\sim$ 2) and the maximum mass of neutron star is explored within a relativistic mean field model. Values of the interaction parameters governing the isovector strengths and the symmetry elements are determined in tighter bounds. Assessments based on the sensitivity matrix reveal that the properties of extreme neutron-rich systems play a predominant role in narrowing down the uncertainties in the various symmetry energy parameters. The calculations are extended over a wide range of nuclear matter density and the results are discussed.Comment: 9 pages, 7 figures (Accepted in Physical Review C

Correlations among symmetry energy elements in Skyrme models

Motivated by the interrelationships found between the various symmetry energy elements of the energy density functionals (EDF) based on the Skyrme forces, possible correlations among them are explored. A total of 237 Skyrme EDFs are used for this purpose. As some of these EDFs yield values of a few nuclear observables far off from the present acceptable range, studies are done also with a subset of 162 EDFs that comply with a conservative set of constraints on the values of nuclear matter incompressibility coefficient, effective mass of the nucleon and the isovector splitting of effective nucleon masses to see the enhancement of the correlation strength, if any. The curvature parameter $K^0_{sym}$ and the skewness parameter $Q^0_{sym}$ of the symmetry energy are found to be very well correlated with the linear combination of the symmetry energy coefficient and its density derivative $L_0$ . The isovector splitting of the effective nucleon mass, however, displays a somewhat meaningful correlation with a linear combination of the symmetry energy, its slope and its curvature parameter.Comment: 8 pages, 3 figures, Accepted for publication in Int. Jour. of Mod. Phys.

Quaternary Heusler Alloy: An Ideal Platform to Realize Triple Point Fermion

The existence of three fold rotational, mirror and time reversal symmetries often give rise to the triply degenerate nodal point (TP) in the band structure of a material. Based on point group symmetry analysis and first principle electronic structure, we predict, in this article, a series of quaternary Heusler alloys host an ideal platform for the occurrence of TP. We simulated, the projection of these TPs onto the (111) and (100) surfaces lead to form topological Fermi arcs, which may further be detected by scanning tunneling spectroscopy and angle resolved photoemission spectroscopy. These Fermi arcs arise due to the symmetry protected band degeneracies, which are robust and can not be avoided due to the non-trivial band topology. Interestingly the TPs, in these class of Heusler alloys are far away from the $\Gamma$ point along C$_3$ axes, which allow to overcome the experimental difficulties over previously studied hexagonal and HgTe-type compounds

Limiting symmetry energy elements from empirical evidence

In the framework of an equation of state (EoS) constructed from a momentum and density-dependent finite-range two-body effective interaction, the quantitative magnitudes of the different symmetry elements of infinite nuclear matter are explored. The parameters of this interaction are determined from well-accepted characteristic constants associated with homogeneous nuclear matter. The symmetry energy coefficient $a_2$, its density slope $L_0$, the symmetry incompressibility $K_\delta$ as well as the density dependent incompressibility $K(\rho )$ evaluated with this EoS are seen to be in good harmony with those obtained from other diverse perspectives. The higher order symmetry energy coefficients $a_4,~a_6$ etc are seen to be not very significant in the domain of densities relevant to finite nuclei, but gradually build up at supra-normal densities. The analysis carried with a Skyrme-inspired energy density functional obtained with the same input values for the empirical bulk data associated with nuclear matter yields nearly the same results.Comment: Accepted in "International journal of Modern Physics E

Measurement of azimuthal dependent muon flux by 2\,m\,×\times\,2\,m RPC stack at IICHEP-Madurai

The proposed 50 \,kton\, INO-ICAL experiment is an upcoming underground high energy physics experiment planned to be commissioned at Bodi hills near Theni, India ($9^{\circ}57'N$, $77^{\circ}16'E$) to study various properties of neutrino oscillations using atmospheric neutrinos produced by extensive air shower phenomenon. The resistive plate chamber has been chosen as the active detector element for the proposed INO-ICAL. An experimental setup consisting a stack of 12 layers of glass resistive plate chambers each with a size of $\sim$2\,m$\times$2\,m has been built at IICHEP, Madurai to study the performance and long-term stability of the resistive plate chambers(RPCs) commercially produced in large quantities by the Indian industries as well as its electronics for the front-end and subsequent signal processing. In this study, the azimuthal dependence of muon flux at various zenith angles at Madurai (9$^{\circ}$56'N, 78$^{\circ}$00'E and at an altitude of 160\,m above mean sea level) has been presented along with the comparison of Monte Carlo from CORSIKA and HONDA predictions.Comment: arXiv admin note: text overlap with arXiv:1706.0090

Interdependence of different symmetry energy elements

Relations between the nuclear symmetry energy coefficient and its density derivatives are derived. The relations hold for a class of interactions with quadratic momentum dependence and a power-law density dependence. The structural connection between the different symmetry energy elements as obtained seems to be followed by almost all reasonable nuclear energy density functionals, both relativistic and non-relativistic, suggesting a universality in the correlation structure. This, coupled with known values of some well-accepted constants related to nuclear matter, helps in constraining values of different density derivatives of the nuclear symmetry energy shedding light on the isovector part of the nuclear interaction.Comment: 6 pages, 2 figure

Measurement of Cosmic Muon angular distribution and vertical integrated flux by 2m×\times2m RPC stack at IICHEP-Madurai

The 50 \,kton\, INO-ICAL is a proposed underground high energy physics experiment at Theni, India ($9^{\circ}57'N$, $77^{\circ}16'E$) to study the neutrino oscillation parameters using atmospheric neutrinos. The Resistive Plate Chamber (RPC) has been chosen as the active detector element for the ICAL detector. An experimental setup consisting of 12 layers of glass RPCs of size 2\,m\,$\times$\,2\,m has been built at IICHEP, Madurai to study the long term stability and performance of RPCs which are produced on a large scale in Indian industry. In this paper, the studies on the performance of RPCs are presented along with the angular distribution of muons at Madurai ($9^{\circ}56'N,78^{\circ}00'E$ and Altitude $\approx$\,160\,m from sea level).Comment: Total number of pages 12 and 4 figure