120000887
Angular resolution of the Ooty EAS array based on UHE gamma rays from Her X-1
The angular resolution of an extensive air shower array for studies on cosmic sources of ultra-high-energy gamma rays has been determined by most of the experimental groups generally by inter-comparison between sub-arrays, in the absence of the knowledge of any steady and strong discrete source. The sub-arrays have been obtained mostly by dividing the main array into two arrays, one containing the even-numbered detectors and another having the odd-numbered detectors. Using this method the angular resolution of the 24-detector array operated at Ooty during 1984-7 was estimated to be about 1.5 degrees . Recently the Ooty group has reported the detection of four episodes of pulsed emission of ultra-high-energy photons from Her X-1 which have been shown to be phase locked with a period of 1.2357701 s. The authors have made a study of the angular resolution for the Ooty array using this signal from Her X-1 which had a relatively low background. The angular resolution of the array has been determined to be 1.6 degrees +or-0.4 degrees . This is the first direct measurement of angular resolution of an air shower array using a point source of ultra-high-energy photons.
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.
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.
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.
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.
119081223
The Wroblewski parameter from lattice QCD
Enhancement of strangeness production has for long been proposed as a promising signal of quark-gluon plasma production. A convenient indicator for it is the Wroblewski parameter which has been shown to be about a factor of 2 higher in heavy-ion collisions. Using a method proposed by us earlier, we obtained lattice QCD results for the Wroblewski parameter from our simulations of QCD with two light quarks both below and above the chiral transition. Our first principles based and parameter-free result compares well with the A-A data.
121535698
Intermittency analysis of fragmenting nuclei with exact conservation laws
We show that the speculative charge bin size dependence of the scaled factorial moments for fragmenting nuclei in recent nuclear emulsion data may be attributed in part to simple conservation laws. Monte Carlo results from both the Thermodynamic Model and an Evaporation Model suggest that in such studies most or all of the effect is due to the fact that there exist constraints owing to conserved quantities.
118650256
Absolutely anticommuting (anti-)BRST symmetry transformations for topologically massive Abelian gauge theory
We demonstrate the existence of the nilpotent and absolutely anticommuting Becchi–Rouet–Stora–Tyutin (BRST) and anti-BRST symmetry transformations for the four (3+1)-dimensional (4D) topologically massive Abelian U(1) gauge theory that is described by the coupled Lagrangian densities (which incorporate the celebrated (B∧F) term). The absolute anticommutativity of the (anti-) BRST symmetry transformations is ensured by the existence of a Curci–Ferrari type restriction that emerges from the superfield formalism as well as from the equations of motion which are derived from the above coupled Lagrangian densities. We show the invariance of the action from the point of view of the symmetry considerations as well as superfield formulation. We discuss, furthermore, the topological term within the framework of superfield formalism and provide the geometrical meaning of its invariance under the (anti-)BRST symmetry transformations.
120031477
Theory of Longitudinal Photons in Quantum Electrodynamics
The radiation field is quantized by introducing four types of photons - two transverse, one longitudinal, and one scalar. The scalar photons are treated by using an indefinite metric, and it is found necessary to modify the usual supplementary condition slightly. The present theory offers a justification for the symmetrical treatment of the four components of the electromagnetic potential, recently applied by a number of authors, and proves to be very convenient in applications. The results of physical interest, however, are the same as obtained from the ordinary formulation.
123456693
NONLINEAR LAGRANGIAN TRANSFORMATIONS.