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V. S. Subrahmanyam

Publications and source records attributed to V. S. Subrahmanyam.

6 recordsLinked to original sources
arXiv2017

Physics Potential of the ICAL detector at the India-based Neutrino Observatory (INO)

The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substantially. Its charge identification capability, and hence its ability to distinguish neutrinos from antineutrinos, makes it an efficient detector for determining the neutrino mass hierarchy. In this report, we outline the analyses carried out for the determination of neutrino mass hierarchy and precision measurements of atmospheric neutrino mixing parameters at ICAL, and give the expected physics reach of the detector with 10 years of runtime. We also explore the potential of ICAL for probing new physics scenarios like CPT violation and the presence of magnetic monopoles.

physics.ins-det↗
arXiv2016

Design and Performance of a Hybrid Fast and Thermal Neutron Detector

We report the performance and characterization of a custom-built hybrid detector consisting of BC501A liquid scintillator for fast neutrons and BC702 scintillator for thermal neutrons. The calibration and the resolution of the BC501A liquid scintillator detector are performed. The event identification via Pulse Shape Discrimination (PSD) technique is developed in order to distinguish gamma, fast and thermal neutrons. Monte Carlo simulation packages are developed in GEANT4 to obtain actual neutron energy spectrum from the measured recoil spectrum. The developed methods are tested by reconstruction of 241AmBe(α, n) neutron spectrum.

physics.ins-det↗
arXiv2016

Characterization and Performance of Germanium Detectors with sub-keV Sensitivities for Neutrino and Dark Matter Experiments

Germanium ionization detectors with sensitivities as low as 100 eVee (electron-equivalent energy) open new windows for studies on neutrino and dark matter physics. The relevant physics subjects are summarized. The detectors have to measure physics signals whose amplitude is comparable to that of pedestal electronic noise. To fully exploit this new detector technique, various experimental issues including quenching factors, energy reconstruction and calibration, signal triggering and selection as well as evaluation of their associated efficiencies have to be attended. The efforts and results of a research program to address these challenges are presented.

physics.ins-det↗
arXiv2016

Measurement of Characteristic Impedance of Silicon Fiber Sheet based readout strips panel for RPC detector in INO

The India based Neutrino Observatory (INO) is a mega science project of India, which is going to use near about 30, 000 Resistive Plate Chambers (RPC) as active detector elements for the study of atmospheric neutrino oscillations. Each RPC detector will consist of two orthogonally placed readout strips panel for picking the signals generated in the gas chamber. The area of RPC detector in INO-ICAL (Iron Calorimeter) experiment will be 2m x 2m, therefore the dimension of readout strips panel will also be of 2m x 2m. To get undistorted signals pass through the readout strips panel to frontend electronics, their Characteristic Impedance should be matched with each other. For the matching of Characteristic Impedance we have used the principle of termination. In the present paper we will describe the need and search of new dielectric material for the fabrication of flame resistant, waterproof and flexible readout pickup strips panel. We will also describe the measurement of Characteristic Impedance of plastic honeycomb based readout strips panel and Silicon Fiber sheet based readout strips panel in a comparative way, and its variation under loading and with time.

physics.ins-det↗
arXiv2006

Effect of the Fe substitution in Ti-Ni shape memory alloys

Shape memory Ti-Ni alloys attracted much attention in the recent years, since they are shape memory, intelligent as well as functional materials. In the present investigation Ti51Ni49 and Ti51Ni45Fe4 alloys were synthesized through radio frequency (RF) induction melting. The alloy was characterized through x-ray diffraction (XRD), scanning electron microscopy (SEM), Mossbauer spectroscopy (MS) and positron annihilation techniques (PAT).The Fe substitution stabilized the TiNi type cubic (a=2.998 A) phase. The surface microstructure and presence of the oxide layer in Ti51Ni45Fe4 alloy have been investigated by SEM. The Positron annihilation measurements indicated a similar bulk electron density in both the as-cast and annealed (1000 0 C for 30 hrs) alloys, typically like that of bulk Ti. Mossbauer spectroscopy studies of as-cast and annealed iron substituted samples showed regions in the samples where nuclear Zeeman splitting of Fe levels occurred and an oxide phase was found to be present in as cast Ti51Ni45Fe4 alloy, while annealed sample indicated the presence of bcc iron phase .

cond-mat.mtrl-sci↗