118567719
A Study of Nuclear Composition of Primary Cosmic Rays above 100 TeV
The GRAPES-3 air shower array is located at Ooty (800g/cm) in southern India and consists of 256 scintillation detectors (1m each) and 16 muon detectors (35m each). In order to study the nuclear composition of primary cosmic rays around the knee energy, we investigate the relation between muon multiplicity and shower size using observations from this experiment during the period, 2000– 2001 with ∼ 10 showers having Ne > 10. These results are compared with Monte Carlo simulations (CORSIKA v6.02 with QGSJET model) to obtain the variation of the average mass number with primary energy. We have carried out detailed simulations for five types of primary nucleus (Proton, He, N, Al and Fe) for comparison with observations. We present here the details of the results.
30676639
Ultrahigh-energy pulsed emission from Hercules X-1 with anomalous air-shower muon production.
A search for bursts of air-shower events from Hercules X-1 at energies above 50 TeV during the calendar period 2 April 1986 to 5 July 1987 yielded two significant bursts, both occurring on UT 24 July 1986. The events during these bursts were pulsed with a period of 1.235 68 s, significantly different from estimates of the contemporaneous x-ray period. The probability that this represents random statistical fluctuations of the background is estimated to be 2 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}5}$. The muon content of the burst events is anomalous when compared with expectations from $\ensuremath{\gamma}$-ray showers.
21268625
Search for signals from Cygnus X-3 at energies above 50 TeV.
Upper limits for the time-averaged flux of air showers from the direction of Cygnus X-3 during the calendar period 2 April 1986 to 3 May 1987 are found to be 1.5 x 10/sup -13/ cm/sup -2/ sec/sup -1/ for all events, and 7.6 x 10/sup -14/ cm/sup -2/ sec/sup -1/ for events with no observed muons in a 44-m/sup 2/ muon detector. These are integral fluxes above 50 TeV on the assumption of an E/sup -1/ primary spectrum. A possible observation of a short-term signal from Cygnus X-3, with an anomalous muon content, phase correlated with the 4.8-h orbital period, with an integral flux above 50 TeV of (8.2 +- 2.0) x 10/sup -13/ cm/sup -2/ sec/sup -1/ is also reported.
124703371
FEL ACTIVITIES IN INDIA
We are building a Compact Ultrafast TErahertz FreeElectron Laser (CUTE-FEL), designed to lase from 50 – 100 μm. The FEL will be driven by a 10-15 MeV electron beam from a Plane-Wave Transformer (PWT) linac. The undulator is a 5 cm period, 2.5 m long PPM planar undulator. We present details of the FEL design and the present status of activities. We also present very preliminary plans for a short-wavelength SASE FEL in India.
331919
Monte Carlo code G3sim for simulation of plastic scintillator detectors with wavelength shifter fiber readout.
A detailed description of a compact Monte Carlo simulation code "G3sim" for studying the performance of a plastic scintillator detector with wavelength shifter (WLS) fiber readout is presented. G3sim was developed for optimizing the design of new scintillator detectors used in the GRAPES-3 extensive air shower experiment. Propagation of the blue photons produced by the passage of relativistic charged particles in the scintillator is treated by incorporating the absorption, total internal, and diffuse reflections. Capture of blue photons by the WLS fibers and subsequent re-emission of longer wavelength green photons is appropriately treated. The trapping and propagation of green photons inside the WLS fiber is treated using the laws of optics for meridional and skew rays. Propagation time of each photon is taken into account for the generation of the electrical signal at the photomultiplier. A comparison of the results from G3sim with the performance of a prototype scintillator detector showed an excellent agreement between the simulated and measured properties. The simulation results can be parametrized in terms of exponential functions providing a deeper insight into the functioning of these versatile detectors. G3sim can be used to aid the design and optimize the performance of scintillator detectors prior to actual fabrication that may result in a considerable saving of time, labor, and money spent.
13571448
Apparent and Actual Shifts in Mass and Width of ϕ Mesons Produced in Heavy-Ion Collisions
We present a method of analyzing invariant-mass spectra of kaon pairs resulting from decay of ϕ mesons produced in high-energy heavy-ion collisions. It can be used to extract the shifts in the mass and the width (ΔM and ΔΓ) of the ϕ mesons when they are inside the dense matter formed in these collisions. We illustrate our method with the help of available preliminary data. Extracted values of ΔM and ΔΓ are significantly larger than those obtained with an earlier method. Our results are consistent with the experimentally observed pT dependence of the mass shift. Finally, we present a phenomenological relation between ΔM and ΔΓ. It provides a useful constraint on theories which predict the values of these two quantities.
15293327
Liquid-Gas Phase Transition in Nuclear Multifragmentation
Heavy-ion collisions allow one to pump energy into a nuclear system. In central collisions of equal size nuclei one can also create a significant amount of compression using high energy nuclear beams. The possibility of studying nuclei far from normal conditions raises the question: can we study phase transitions in nuclei similar, for instance, to the way, one can study phase transition in water? This is the subject of the present article.
124737204
Thermalization of quarkonia at energies available at the CERN Large Hadron Collider
We argue that the relative yields of $\Upsilon$ states observed at the LHC can be understood as bottomonium states coming to early thermal equilibrium and then freezing out. The bottomonium freezeout temperature is approximately 250 MeV. We examine its systematics as a function of centrality. We remark on the interesting differences seen by the CMS and ALICE experiments in the charmonium sector.
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.
14528390
Distinguishing the Littlest Higgs model with T-parity from supersymmetry at the LHC using trileptons
Abstract We analyse hadronically quiet trilepton signatures in the T-parity conserving Littlest Higgs model and in R-parity conserving supersymmetry at the Large Hadron Collider. We identify the regions of the parameter space where such signals can reveal the presence of these new physics models above the Standard Model background and distinguish them from each other, even in a situation when the mass spectrum of the Littlest Higgs model resembles the supersymmetric pattern.
118643338
An Interacting Gauge Field Theoretic Model for the Hodge Theory: Basic Canonical Brackets
We derive the basic canonical brackets amongst the creation and annihilation operators for a two (1 + 1)-dimensional (2D) gauge field theoretic model of an interacting Hodge theory where a U(1) gauge field (A_\mu) is coupled with the fermionic Dirac fields (\psi and \bar \psi). In this derivation, we exploit the spin-statistics theorem, normal ordering and the strength of the underlying six infinitesimal continuous symmetries (and the concept of their generators) that are present in the theory. We do not use the definition of the canonical conjugate momenta (corresponding to the basic fields of the theory) anywhere in our whole discussion. Thus, we conjecture that our present approach provides an alternative to the canonical method of quantization for a class of gauge field theories that are physical examples of Hodge theory where the continuous symmetries (and corresponding generators) provide the physical realizations of the de Rham cohomological operators of differential geometry at the algebraic level.