A5101774295- Astrophysics and Cosmic Phenomena
- Particle Detector Development and Performance
- Gamma-ray bursts and supernovae
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Radiation Detection and Scintillator Technologies
- Particle Accelerators and Free-Electron Lasers
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Atomic and Subatomic Physics Research
- Geophysics and Gravity Measurements
- Astronomy and Astrophysical Research
- Nuclear Physics and Applications
- Adaptive optics and wavefront sensing
- CCD and CMOS Imaging Sensors
- High-Voltage Power Transmission Systems
- Particle physics theoretical and experimental studies
- Lattice Boltzmann Simulation Studies
- Inertial Sensor and Navigation
- Medical Imaging Techniques and Applications
- Nanofluid Flow and Heat Transfer
- Structural Response to Dynamic Loads
- Space Satellite Systems and Control
- Radio Wave Propagation Studies
- Digital Transformation in Industry
Tata Institute of Fundamental Research
2012-2023
Panjab University
1991
Context:The HAGAR Telescope Array at Hanle, Ladakh has been regularly monitoring the nearby blazar Mkn 421 for past 7yrs. Aims: Blazars show flux variability in all timescales across electromagnetic spectrum. While there is abundant literature characterizing short term flares from different blazars, comparatively little work done to study long variability. We aim temporal and spectral radiation during 2009-2015. Methods: quantify lognormality radio VHE bands, compute correlations between...
Context: The nearby (z=0.031) TeV blazar Mrk421 was reported to be in a high state of flux activity since November, 2009. Aims: To investigate possible changes the physical parameters during its using multiwavelength data. Methods: We have observed this source bright High Altitude GAmma Ray (HAGAR) telescope array at energies above 250 GeV February 13 - 19, 2010. Optical, X-ray and gamma-ray archival data are also used obtain SEDs light curves. Results: found undergo one brightest flaring...
Since the detection of very high energy (VHE) γ-rays from Mrk 501, its broadband emission radiation was mostly and quite effectively modeled using one zone scenario. However, spectral flux variability studies enabled by multi-wavelength campaigns carried out during recent years have revealed rather complex behavior 501. The observed 501 could be due to a superposition multiple zones. Moreover, new evidence hard intrinsic γ-ray spectra obtained Fermi-LAT observations has challenged theories...
A detailed multi-epoch study of the broadband spectral behaviour very high energy (VHE) source, 1ES\,1011+496, provides us with valuable information regarding underlying particle distribution. Simultaneous observations source at optical/ UV/ X-ray/ $\gamma$-ray during three different epochs, as obtained from Swift-UVOT/ Swift-XRT/ Fermi-LAT, are supplemented available VHE telescope array, HAGAR. The longterm flux variability Fermi-LAT energies is clearly found to be lognormal. It seen that...
The High Altitude GAmma-Ray (HAGAR) ar- ray is a wavefront sampling array of 7 telescopes, set-up at Hanle, 4270 m amsl, in the Ladakh region Hi- malayas (Northern India). It constitutes first phase HImalayan Gamma-Ray Observatory (HIGRO) project. HA- GAR atmospheric Cherenkov telescopes established so high altitude, and was designed to reach relatively low threshold (currently around 200 GeV) with quite mirror area (31 2 ). Regular source observations are running since September 2008....
Abstract In recent years, the Silicon Photomultipliers (SiPMs) have emerged as a promising photodetector in various applications such high energy physics, nuclear physics and medical instruments. One application is pixelated camera of Imaging Atmospheric Cherenkov Telescopes (IACTs). IACTs are used to detect very high-energy celestial gamma rays using Technique. The SiPM gain proportional overvoltage which difference between applied bias voltage breakdown voltage. As increases with...
In last few years, SiPMs have emerged as a viable alternative to PMTs used in the imaging atmospheric Cherenkov telescopes. addition their higher photon detection efficiency, provide attractive features like possible increase observation duty cycle owing safe operation under partial moonlight conditions. Design and development of 256 pixel SiPM based camera for 4m class telescope is currently at an advanced stage. This proposed cover field view 5 deg X deg, with size 0.3 deg. The being...
A Large Size air Cherenkov Telescope (LST) prototype, proposed for the Array, is under construction at Canarian Island of La Palma (Spain) this year. The LST camera, which comprises an array photomultipliers (PMTs), requires a precise and regular calibration over large dynamic range. We present system built to provide optical camera consisting pulsed laser (355 nm wavelength, 400 ps pulse width), set filters guarantee range photons on sensors, diffusing sphere uniformly spread light , with...
The Cherenkov Telescope Array is a project that aims to exploring the highest energy region of electromagnetic spectrum. Two arrays, one for each hemisphere, will cover full sky in range from few tens GeV hundreds TeV improving sensitivity and angular resolution present operating arrays. A prototype Large Size (LST) study gamma ray astronomy above some be installed at Canary Island La Palma 2016. LST camera, made by an array photomultipliers (PMTs), requires accurate systematic calibration...
In this letter we show that most of the fluctuations in particle densities observed relativistic heavy-ion collisions are consistent with stochastic emission, i.e., correlations between produced particles washed out due to vast number environment. We further explore general trends by investigating different systems, energies and centrality cuts. Comparisons Fritiof model string fragmentation gives results similar data.