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G. Majumder

Publications and source records attributed to G. Majumder.

At least 19 recordsLinked to original sources
arXiv2026

Charge-dependent atmospheric muon flux at 17 GV geomagnetic cutoff measured with the mini-ICAL prototype

The Iron CALorimeter (ICAL) detector at the India-Based Neutrino Observatory (INO) was conceived as an underground experiment designed to measure atmospheric neutrino oscillation parameters. As part of the R\&D programme, a scaled prototype (mini-ICAL), 85\,ton, approximately 1/600$^{\mathrm{th}}$ the mass of the full detector, was constructed at the IICHEP Transit Campus, Madurai (altitude 150\,m; latitude 9.9372$^\circ$\,N; longitude 78.013$^\circ$\,E; geomagnetic latitude 1.44$^\circ$\,N; vertical cutoff rigidity 17\,GV) and operated between 2018 and 2022. The prototype enabled measurements of charge-dependent cosmic muon spectra in the vicinity of the geomagnetic equator and provided an important validation of detector performance, reconstruction algorithms, and simulation frameworks for the ICAL experiment. Differential fluxes of $\mu^{-}$ and $\mu^{+}$ were measured over the momentum range $\sim$\,1--5\,GeV/c. The obtained momentum spectra are systematically lower than those reported at sites with smaller geomagnetic cutoff rigidities, consistent with the suppression of low- and intermediate-rigidity primary cosmic rays at the 17\,GV cutoff. The measurements are compared with predictions from different hadronic interaction models available in CORSIKA simulations.

hep-ex↗
arXiv2024

Charge ratio of cosmic ray muons in momentum range ~ 1 to 3 GeV/c

This work presents the measurements of the cosmic muon charge ratio as a function of full azimuthal angle and momentum within the range of 0.8 to 3.0 GeV/c, using the mini-ICAL detector. The detector, comprising 10 layers of RPCs, has collected cosmic muon data since August 2018 till recent time, at an altitude of 160 m above sea level at the Inter-Institutional Center for High Energy Physics in Madurai, India $(9^\circ56'\,N, 78^\circ00'\,E)$. The muon charge identification is achieved through the use of a magnetic field of strength 1.4 T. The analysis shows that the cosmic muon charge ratio, $R_\mu = N_{\mu^+}/N_{\mu^-}$, ranges from 1.1 to 1.2 and has small dependency on the zenith angle. The charge ratio's dependence on momentum and azimuthal angle is thoroughly examined for a wide range of zenith angle upto $50^\circ$. These measurements are compared with the predictions from various combinations of different hadronic models in CORSIKA extensive air shower simulations.

hep-ex↗
arXiv2023

Simulation of RPC responses in mini-Iron Calorimeter for cosmic ray muon studies

A Prototype of the Iron Calorimeter for the India-based Neutrino Observatory is currently running in Madurai, India. This consists of twenty large area single gap Resistive Plate Chambers (RPCs) of size, $\sim$ 185\,cm $\times$ 175\,cm sandwiched between 11 layers of iron plates of thickness 5.6\,cm. The total size of the mini-Iron Calorimeter(mini-ICAL) is 4\,m$\times$4\,m$\times$1.2\,m and having a weight of 85\,tons is a (1/600) scaled-down version of the ICAL detector of INO~\cite{ichep2018}. The detector is magnetized using iron plates and two sets of copper coils, each coil has 18 turns. The central region of the mini-ICAL, where the RPCs are placed, has a nearly uniform magnetic field of 1.4\,T, similar to the magnetic field in the final ICAL detector. This prototype serves as the basis for the design of the demonstrators, which closely mimics the characteristics of a future ICAL. This detector is built to test the final electronics in the fringe field of the magnet and also to develop the experience to construct the ICAL detector. The mini-ICAL has been operational since 2018 and collects cosmic muon data with different configurations of RPC, and electronics, which are continuously changing for various R\&D efforts. Dedicated efforts are made in parallel to measure the momentum and azimuthal angle of $μ^+$ and $μ^-$ independently, which could be an important input to the cosmic neutrino event generators. To improve the precision of those measurements a dedicated simulation effort was made, particularly in the digitisation of the RPC signal for a real detector simulation, where efficiency, noise rate, strip multiplicity, etc. were matched with the real data collected during runs at mini-ICAL.

physics.ins-det↗
arXiv2023

Improving Time and Position Resolution of RPC detectors using Time Over Threshold Information

INO-ICAL is a proposed underground particle physics experiment to study the neutrino oscillation parameters by detecting neutrinos produced in the atmospheric air showers. Iron CALorimeter (ICAL) is to have 151 layers of iron stacked vertically, with active detector elements in between the iron layers. The iron layers will be magnetized to enable the measurement of momentum and charge of the $μ^-$ (or $μ^+$) produced by $ν_μ$ (or $\barν_μ$) interactions. Resistive Plate Chambers (RPCs) have been chosen as the active detector elements due to their large area coverage, uncompromised sensitivity, consistent performance for decades, as well as cost effectiveness. The major factors that decide the physics potential of the ICAL experiment are efficiency, position resolution and time resolution of the large area RPCs. A prototype detector called miniICAL (with 11 iron layers) was commissioned to understand the engineering challenges in building the large scale magnet and its ancillary systems, and also to study the performance of the RPC detectors and readout electronics developed by the INO collaboration. As part of the performance study of the RPC detectors, an attempt is made to improve the position and time resolution of them. Even a small improvement in the position and time resolution will help to improve the measurements of momentum and directionality of the neutrinos in ICAL. The Time-over-Threshold (ToT) of the RPC pulses (signals) is recorded by the readout electronics. ToT is a measure of the pulse width and consequently the amplitude. This information is used to improve the time and position resolution of the RPCs and consequently INO physics potential.

physics.ins-det↗
arXiv2022

Optimisation of Operating High Voltage of the large area Resistive Plate Chamber for ICAL experiment

The Resistive Plate Chamber is a widely used detector in high energy physics. The operating potential of this chamber is determined by the optimisation of the efficiency and noise rate of the device. This optimisation is based on the assumption that the performance of the device over the whole surface area is uniform. The INO-ICAL experiment is going to use $\sim$ 30000 RPC of size $\sim$2\,m$\times$2\,m. All the RPC will have to pass a minimum quality assurance criteria, but may not be able to maintain a good uniformity over the whole surface area, particularly for the whole running period of about twenty years. This paper describes the choice of the optimum operating HV for an RPC of non-uniform response.

physics.ins-det↗
arXiv2020

Measurement of azimuthal dependent muon flux by 2\,m\,$\times$\,2\,m RPC stack at IICHEP-Madurai

The proposed 50 \,kton\, INO-ICAL experiment is an upcoming underground high energy physics experiment planned to be commissioned at Bodi hills near Theni, India ($9^{\circ}57'N$, $77^{\circ}16'E$) to study various properties of neutrino oscillations using atmospheric neutrinos produced by extensive air shower phenomenon. The resistive plate chamber has been chosen as the active detector element for the proposed INO-ICAL. An experimental setup consisting a stack of 12 layers of glass resistive plate chambers each with a size of $\sim$2\,m$\times$2\,m has been built at IICHEP, Madurai to study the performance and long-term stability of the resistive plate chambers(RPCs) commercially produced in large quantities by the Indian industries as well as its electronics for the front-end and subsequent signal processing. In this study, the azimuthal dependence of muon flux at various zenith angles at Madurai (9$^{\circ}$56'N, 78$^{\circ}$00'E and at an altitude of 160\,m above mean sea level) has been presented along with the comparison of Monte Carlo from CORSIKA and HONDA predictions.

hep-ex↗
arXiv2019

Development and characterization of six-gap glass MRPCs and feasibility study of a PET device

The Multigap Resistive Plate Chambers (MRPCs) provide excellent timing as well as position resolutions at relatively low cost. Therefore, they can be used in medical imaging applications such as PET where precise timing is a crucial parameter of measurement. We have designed and fabricated several six-gap glass MRPCs and extensively studied their performance. In this paper, we describe the fabrication and characterization of the detector, the electronics and the data acquisition system of the setup. We present here the result of our Time Of Flight (TOF) experiment using a radioactive source Na-22 hence to demonstrate their potential applications in medical imaging. We also present the Geant4 based simulation results on the efficiency of our detector as a function of the number of gaps and thickness of the converter material.

physics.ins-det↗
arXiv2019

Simulation of muon-induced neutral particle background for a shallow depth Iron Calorimeter detector

The Iron Calorimeter (ICAL) detector at the India based Neutrino Observatory (INO) is planned to be set up in an underground cavern with a rock overburden of more than 1 km. This overburden reduces the cosmic muon flux by a factor of 10$^{6}$ with respect to that at sea level. In this paper, we examine the possibility of a 100 m shallow depth ICAL (SICAL) detector. The cosmic muons would have to be detected in a veto detector surrounding ICAL with an efficiency of 99.99 % in order to have the same level of muon background leaking undetected through the veto detector as at the 1 km depth underground site. However, an additional background arises from interactions of cosmic muons with the rock. Since the neutral particles produced in such interactions can pass through the veto detector without any interaction, they can possibly mimic neutrino events in ICAL. In this paper, the results of a GEANT4 based simulation study to estimate the background signals due to muon induced interactions with the rock for SICAL are presented.

physics.ins-det↗
arXiv2019

A compact cosmic muon veto detector and possible use with the Iron Calorimeter detector for neutrinos

The motivation for a cosmic muon veto (CMV) detector is to explore the possibility of locating the proposed large Iron Calorimeter (ICAL) detector at the India based Neutrino Observatory (INO) at a shallow depth. An initial effort in that direction, through the assembly and testing of a $\sim$ 1 m $\times$ 1 m $\times$ 0.3 m plastic scintillator based detector, is described. The plan for making a CMV detector for a smaller prototype mini-ICAL is also outlined.

physics.ins-det↗
arXiv2017

Measurement of Cosmic Muon angular distribution and vertical integrated flux by 2m$\times$2m RPC stack at IICHEP-Madurai

The 50 \,kton\, INO-ICAL is a proposed underground high energy physics experiment at Theni, India ($9^{\circ}57'N$, $77^{\circ}16'E$) to study the neutrino oscillation parameters using atmospheric neutrinos. The Resistive Plate Chamber (RPC) has been chosen as the active detector element for the ICAL detector. An experimental setup consisting of 12 layers of glass RPCs of size 2\,m\,$\times$\,2\,m has been built at IICHEP, Madurai to study the long term stability and performance of RPCs which are produced on a large scale in Indian industry. In this paper, the studies on the performance of RPCs are presented along with the angular distribution of muons at Madurai ($9^{\circ}56'N,78^{\circ}00'E$ and Altitude $\approx$\,160\,m from sea level).

physics.ins-det↗
arXiv2014

A Study on the time resolution of Glass RPC

The 50~kton Iron Calorimeter (ICAL) detector at the underground India based Neutrino Observatory (INO) will make measurements on atmospheric neutrinos. Muons produced in charged current (CC) interactions of muon neutrinos with the iron are tracked spatially and temporally through the signals that they produce in the Resistive Plate Chambers~(RPCs) that are interleaved with iron layers. Since the RPCs will be operated in the avalanche mode the signal rise-time is $\sim~1~\rm{nsec}$ resulting in a fast time response. While the muon track is derived from the X and Y hit information of the RPCs and the layer number (Z), the upward or downward direction is obtained by using the time information from the detector. Such a capability can be examined by analysing the timing information from $1~\rm{m}~\times~1~\rm{m}$ glass RPCs, with $3~\rm{cm}$ wide X- and Y- pick-up strips, in a $12$ layer RPC stack that measures cosmic muon events. The present study looks at the pixel-wise time response of these RPCs in order to improve the relative time distribution and hence the up-down discrimination capability. After including the effect of propagation delay in the cable and pick-up panel the time resolution improves, in some cases, to $\leq~1~\rm{nsec}$ whereas in some cases there is no significant change. These results will help in significantly improving on the extraction of the directionality of muons produced in CC interactions of $ν_μ$ and $\barν_μ$.

physics.ins-det↗
arXiv2014

Sensitivity for detection of decay of dark matter particle using ICAL at INO

We report on the simulation studies on the possibility of dark matter particle (DMP) decaying into leptonic modes. While not much is known about the properties of dark matter particles except through their gravitational effect, it has been recently conjectured that the so called "anomalous Kolar Events" observed some decades ago may be due to the decay of unstable dark matter particles (M.V.N. Murthy and G.Rajasekaran, Pramana, {\bf 82}, 609 (2014)). The aim of this study is to see if this conjecture can be verified at the proposed Iron Calorimeter (ICAL) detector at INO. We study the possible decay to leptonic modes which may be seen in this detector with some modifications. For the purposes of simulation we assume that each channel saturates the decay width for the mass ranging from $1-50 \rm{GeV/c^2}$. The aim is not only to investigate the decay signatures, but also, more generally, to establish lower bounds on the life time of DMP even if no such decay takes place.

hep-ex↗
arXiv2014

Search for Magnetic Monopole using ICAL at INO

Sub-relativistic magnetic monopoles are predicted from the GUT era by theory. To date there have been no confirmed observations of such exotic particles. The Iron CALorimeter (ICAL) at India-based Neutrino Observatory (INO) aims to measure the neutrino oscillation parameters precisely. As it is a tracking detector there is also the possibility of detecting magnetic monopoles in the sub-relativistic region. Using ICAL the magnetic monopole event is characterised by the large time intervals of upto 30 microsec between the signals in successive layers of the active detectors. The aim of this study is to identify the sensitivity of ICAL for a particle carrying magnetic charge in the mass range from 10^{5} to 10^{17} GeV with beta ranging from 10^{-5} to 9 x 10^{-1} for ICAL at INO. A similar study has also been carried out for the ICAL prototype which will be placed overground. Due to the rock cover of approximately 1.3 km, ICAL at INO will not be able to place bounds on the flux of the lower mass magnetic monopoles. This mass region is however addressed by the prototype ICAL.

physics.ins-det↗
arXiv2006

Observation of a Near-threshold $D^0\bar{D}^0π^0$ Enhancement in $B \to D^0\bar{D}^0π^0 K$ Decay

We report the first observation of a near-threshold enhancement in the $D^0\bar{D}^0π^0$ system from $B \to D^0\bar{D}^0π^0 K$ decays using a 414 $\mathrm{fb}^{-1}$ data sample collected at the $Υ(4S)$ resonance. The enhancement peaks at a mass $M=3875.4 \pm 0.7_{-2.0}^{+1.2}$ MeV/$c^2$ and the branching fraction for events in the peak is \Br ($B \to D^0\bar{D}^0π^0 K$)=(1.27 $\pm$ 0.31 $_{-0.39}^{+0.22})$ $\times$ $10^{-4}$. The data were collected with the Belle detector at the KEKB energy-asymmetric $e^+e^-$ collider.

hep-ex↗
arXiv2005

The Cleo Rich Detector

We describe the design, construction and performance of a Ring Imaging Cherenkov Detector (RICH) constructed to identify charged particles in the CLEO experiment. Cherenkov radiation occurs in LiF crystals, both planar and ones with a novel ``sawtooth''-shaped exit surface. Photons in the wavelength interval 135--165 nm are detected using multi-wire chambers filled with a mixture of methane gas and triethylamine vapor. Excellent pion/kaon separation is demonstrated.

physics.ins-det↗
arXiv2005

Observation of $B^0 \to D^+ D^-$, $B^- \to D^0 D^-$ and $B^- \to D^0 D^{*-}$ decays

We report the first observation of the decay modes $B^0 \to D^+ D^-$, $B^- \to D^0 D^-$ and $B^- \to D^0 D^{*-}$ based on 152 $\times$ 10$^6$ $B\bar{B}$ events collected at KEKB. The branching fractions of $B^0 \to D^+ D^-$, $B^- \to D^0 D^-$ and $B^- \to D^0 D^{*-}$ are found to be $(3.21 \pm 0.57 \pm 0.48) \times 10^{-4}$, $(5.62 \pm 0.82 \pm 0.65) \times 10^{-4}$ and $(4.59 \pm 0.72 \pm 0.56) \times 10^{-4}$, respectively. Charge asymmetries in the $B^- \to D^0 D^-$ and $B^- \to D^0 D^{*-}$ channels are consistent with zero.

hep-ex↗
arXiv2004

Observation of $B^0 \to D^{*-} (5π)^+$, $B^+ \to D^{*-} (4π)^{++}$ and $B^+ \to \bar{D}^{*0} (5π)^+$

We report the first observation of a number of decay modes of the B meson, namely $B^0 \to D^{*-} (5π)^+$, $B^+ \to D^{*-} (4π)^{++}$ and $B^+ \to \bar{D}^{*0} (5π)^+$, where $(nπ)$ implies the combination of n charged pions. The analysis is based on a 140 fb$^{-1}$ data sample collected at the $Υ(4S)$ resonance with the Belle detector at KEKB. We measure ${\cal{B}}(B^0 \to D^{*-} (5π)^+) = (4.72 \pm 0.59 \pm 0.71) \times 10^{-3}$, ${\cal{B}}(B^+ \to D^{*-} (4π)^{++} = (2.56 \pm 0.26 \pm 0.33) \times 10^{-3}$ and ${\cal{B}}(B^+ \to \bar{D}^{*0} (5π)^+) = (5.67 \pm 0.91 \pm 0.85) \times 10^{-3}$. We also provide improved measurements of the branching fractions for the decay modes $B^0 \to D^{*-} (3π)^+$, $B^+ \to \bar{D}^{*0} (3π)^+$ and $B^0 \to \bar{D}^{*0} (4π)^0$.

hep-ex↗