• S K Gupta

Articles written in Pramana – Journal of Physics

• Heavy ion collisions at collider energies—Insights from PHENIX

• A high-performance, low-cost, leading edge discriminator

A high-performance, low-cost, leading edge discriminator has been designed with a timing performance comparable to state-of-the-art, commercially available discriminators. A timing error of 16 ps is achieved under ideal operating conditions. Under more realistic operating conditions the discriminator displays a timing error of 90 ps. It has an intrinsic double pulse resolution of 4 ns which is better than most commercial discriminators. A low-cost discriminator is an essential requirement of the GRAPES-3 experiment where a large number of discriminator channels are used.

• Measurement of neutron-induced activation cross-sections using spallation source at JINR and neutronic validation of the Dubna code

A beam of 1 GeV proton coming from Dubna Nuclotron colliding with a lead target surrounded by 6 cm paraffin produces spallation neutrons. A Th-foil was kept on lead target (neutron spallation source) in a direct stream of neutrons for activation and other samples of 197Au, 209Bi, 59Co, 115In and 181Ta were irradiated by moderated beam of neutrons passing through 6 cm paraffin moderator. The gamma spectra of irradiated samples were analyzed using gamma spectrometry and DEIMOS software to measure the neutron cross-section. For this purpose neutron fluence at the positions of samples is also estimated using PREPRO software. The results of cross-sections for reactions 232Th($n, \gamma$), 232Th($n, 2n$), 197Au($n, \gamma$), 197Au($n, \alpha$), 197Au($n, xn$), 59Co($n, \alpha$), 59Co($n, xn$), 181Ta($n, \gamma$) and 181Ta($n, xn$) are given in this paper. Neutronics validation of the Dubna Cascade Code is also done using cross-section data by other experiments.

• Solar diurnal anisotropy measured using muons in GRAPES-3 experiment in 2006

The GRAPES-3 experiment at Ooty contains a large-area (560 m$^{2}$) tracking muon detector. This detector consists of 16 modules, each 35 m$^{2}$ in area, that are grouped into four supermodules of 140 m$^{2}$ each. The threshold energy of muons is $\sec(\theta)$ GeV along a direction with zenith angle $\theta$ and the angular resolution of the muon detector is $6^{\circ}$. Typically, it records $\sim 4 \times 10^{9}$ muons every day. The muon detector has been operating uninterruptedly since 2001, thus providing a high statistics record of the cosmic ray flux as a function of time over one decade. However, prior to using these data, the muon rate has to be corrected for two important atmospheric effects, namely, variations in atmospheric pressure and temperature. Because of the near equatorial location of Ooty ($11.4^{\circ}$N), the seasonal variations in the atmospheric temperature are relatively small and shall be ignored here. Due to proximity to the equator, the pressure changes at Ooty display a dominant 12 h periodic behaviour in addition to other seasonal changes. Here, we discuss various aspects of a novel method for accurate pressure measurement and subsequent corrections applied to the GRAPES-3 muon data to correct these pressure-induced variations. The pressure-corrected muon data are used to measure the profile of the solar diurnal anisotropy during 2006. The data, when divided into four segments, display significant variation both in the amplitude ($\sim 45\%$) and phase ($\sim42$ m) of the solar diurnal anisotropy during 2006, which was a period of relatively low solar activity.

• # Pramana – Journal of Physics

Volume 96, 2022
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019

Click here for Editorial Note on CAP Mode

© 2021-2022 Indian Academy of Sciences, Bengaluru.