123618858
An experimental system for detection of high energy cosmic gamma ray bursts
Abstract While bursts of cosmic gamma rays of energies 0.1–10 MeV can be detected and studied only with satellite-borne detectors, bursts of gamma rays at GeV energies can be detected using sensitive ground-based detectors. An experimental system to detect these high energy gamma ray bursts is being operated at the mountain altitude laboratory at Ootacamund, India. The design features and the experimental details related to this system are described.
67815721
The angular resolution of the GRAPES-3 array from the shadows of the Moon and the Sun
Abstract The absence of a well established point source of very high energy ( ≳ 10 TeV ) γ-rays in the sky, makes the measurement of the angular resolution and the absolute pointing accuracy of an extensive air shower (EAS) array a challenging task. In the past, several groups have utilized the reduction in the isotropic flux of cosmic rays due to the shadows of the Moon and the Sun, to measure the angular resolution and the absolute pointing accuracy of their arrays. The data collected from the GRAPES-3 EAS array, over the period of 4 years from 2000 to 2003, has been used to observe the shadow of the Moon at a level of ∼ 5 σ and that of the Sun at a lower level of significance. The high density of the detectors in GRAPES-3 enabled an angular resolution of 0.7° to be obtained at energies as low as 30 TeV. The angular resolution studies were further extended by using two other techniques, namely, the even–odd and the left–right methods. All three techniques have yielded nearly identical results on the energy dependent angular resolution.
55926788
A large area muon tracking detector for ultra-high energy cosmic ray astrophysics — the GRAPES-3 experiment
Certain aspects of ultra-high energy (UHE) cosmic ray astrophysics require correlated studies on the electron and muon components of air showers, namely, the search for cosmic ray sources through g-ray astronomy and studies on the variation of the nuclear composition of primary cosmic rays with energy. While studies on the electron component provide basic information about the arrival direction and energy, it is the muon component that plays a crucial role in distinguishing primary g-rays from charged cosmic ray particles and in determining the composition. A large area (560m), tracking muon detector of the GRAPES-3 experiment, operating at Ooty in southern India, has been designed for detailed studies on both of these aspects of UHE cosmic ray astrophysics. We present here the details of the muon detector, associated electronics and the data acquisition system. A brief discussion of the potential of the muon detector is presented through simulation studies. r 2005 Elsevier B.V. All rights reserved. PACS: 98.70.Sa; 96.40.Pq; 96.40.De; 98.70.Rz; 95.55.Vj; 13.85.Tp
119032709
Emission of Radiation at Energies > 1014 eV: Binary X-Ray Sources SCO X-1, CYG X-1, HER X-1 and Others
55612742
Recent results from the GRAPES-3 experiment
The GRAPES-3 is a dense extensive air shower array operating with ~400 scintillator detectors and a 560 m 2 large tracking muon detector (E μ > 1 GeV), at Ooty in India. The muon detector has been used to observe acceleration of muons during thunderstorm conditions. The muon multiplicity distribution of the EAS is used to probe the composition of primary cosmic rays below 1 PeV, with an overlap with direct measurements. More recently we have explored the possibility of using the angular distribution of >1 GeV muons to identify the best from among several low- and high-energy hadronic interaction models. We have major expansion plans to enhance the sensitivity of the GRAPES-3 experiment in all of the areas listed above.
121254838
Sporadic emission of ultra high energy gamma rays from Crab pulsar
In a further study of sporadic emission from pulsars we find evidence for short lived intense emission from the Crab pulsar.
121323084
Microscopic nucleon optical model potential at low energies
Nuclear optical model potentials at low energies have been computed utilizing the two (Micro I and Micro II) versions of the microscopic optical model of Jeukenne et al. A comparison has been made of the experimental nucleon-nucleus interaction data for E<10 MeV with the theoretical predictions obtained using the microscopic optical model.
12420233
Jet missing transverse momenta for quark-gluon plasma thermometry
Abstract At the LHC, where hard multi-jet events are common, large imbalances in the total jet- p t can arise due to the interaction of jets with the plasma formed in heavy-ion collisions. We find that this missing- p t spectrum yields a measurement of the initial temperature of the plasma. Using commonly accepted guesses for this temperature, and ISAJET estimates for jet cross sections, we predict an order of thousand events at LHC with unbalanced p t >50 GeV.
120871108
Can charge correlations be used to signal the formation of a quark-gluon plasma?
We investigate short-range charge anticorrelations in nucleus-nucleus collisions whose suppresion could signal the presence of a quark-gluon plasma. We compute the charge correlations under some minimal assumptions about model parameters, and find that the results are not very sensitive to different parameters of the model.
118245922
Cygnus experiment at Los Alamos
The Cygnus experiment at Los Alamos National Laboratory has been designed to study, with high angular accuracy, point sources of gamma rays of energy above 1014 eV. The experimental detector consists of an air shower array to observe gamma-ray showers and a shielded, large-area track detector to study the muon content of the showers. In this paper we present preliminary data from the array and describe its performance.
118515325
Lattice QCD predictions for shapes of event distributions along the freezeout curve in heavy-ion collisions
We present lattice QCD results along the freezeout curve of heavy-ion collisions. The variance, skew and kurtosis of the event distribution of baryon number are studied through Pade resummations. We predict smooth behaviour of three ratios of these quantities at current RHIC and future LHC energies. Deviations from this at lower energies signal the presence of a nearby critical point.