arXiv subjects

V. Jha

Publications and source records attributed to V. Jha.

At least 19 recordsLinked to original sources

arXiv2025

Study of neutron response using time of flight technique in ISMRAN detector

We report the measurements of the fast neutron energy response in Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) detector consisting of an array of 9$\times$10 Plastic Scintillator Bars (PSBs) at BARC, Mumbai. ISMRAN is an above ground detector setup at $\sim$13 m from the Dhruva reactor core for the detection of reactor anti-neutrinos (${\overline{\ensuremath{\nu}}}_{e}$) via the inverse beta decay (IBD) process. The dominant sources of reactor-related background in the vicinity of the detector are high energy $\gamma$-rays and fast neutrons. Therefore, a good understanding of fast neutron response in PSB is an essential pre-requisite for suppression and discrimination of the fast neutron background from IBD events. Kinetic energies of the fast neutron were determined using the Time-of-Flight (TOF) technique, which is used to get the scintillation light yield due to recoiling proton in PSB. We also measured the fast neutron capture time distribution in ISMRAN array using a novel technique involving TOF of the measured fast neutrons. The observed characteristic neutron capture time ( $\tau$ ) of 68.29 $\pm$ 9.48 $\mu$s is in good agreement with GEANT4 based MC simulation. These experimentally measured results will be useful for discriminating correlated and uncorrelated (accidental) background events from the true IBD events in reactor ON and OFF conditions inside the reactor hall.

physics.ins-det↗

arXiv2025

Discrimination of neutron-$\gamma$ in the low energy regime using machine learning for an EJ-276D plastic scintillator

In this work, we present results for discrimination of neutron and $\gamma$ events using a plastic scintillator detector with pulse shape discrimination capabilities. Machine learning (ML) algorithms are used to improve the discriminatory power between neutron and $\gamma$ events at lower energy ranges which otherwise are not addressed by the conventional pulse shape discrimination techniques. The use of a multilayer perceptron with Bayesian inference (MLPBNN) and support vector machine (SVM) algorithms are studied using the recorded waveforms from the detector. Input variables are constructed for the ML algorithms, which captures the essence of the differences in the head and tail part of the neutron and $\gamma$ waveforms. A new variable, which utilizes the product of kurtosis and variance calculated from the waveform gives better ranking in terms of separation of neutron and $\gamma$ events. The training and the testing of the ML algorithms are done using an AmBe neutron source. In the lower energy region, the results obtained from the ML predictions are compared with the results obtained from a time of flight (ToF) technique to benchmark the overall performance of the ML algorithms. A reasonable agreement is observed between the results obtained from ML algorithm and the ToF experiment in the studied energy range. The MLPBNN gives better discriminatory power for the neutron and $\gamma$ events than the SVM algorithm.

physics.ins-det↗

arXiv2025

Measurement of cosmic muon-induced neutron background with ISMRAN detector in a non-reactor environment

The Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) is an above-ground, very short baseline reactor anti-neutrino (${\overline{\ensuremath{\nu}}}_{e}$) experiment, located inside the Dhruva research reactor facility, Mumbai, India. The primary goal of the ISMRAN experiment is the indirect detection of reactor ${\overline{\ensuremath{\nu}}}_{e}$ through an inverse beta decay (IBD) process, using a cluster of 90 optically segmented plastic scintillator detectors, weighing $\sim$1 ton. In this work, we present the neutron capture time response and energy deposition of neutron capture signals generated by cosmic muons in the ISMRAN geometry, and we compare these experimental results with Geant4-based Monte Carlo (MC) simulations. The obtained mean capture time of fast neutrons is 74.46 $\pm$ 5.98 $\mathrm{\mu}$s and is comparable with the MC simulation results. The efficiency-corrected rate of muon-induced neutron background inside the ISMRAN geometry, due to the presence of a passive shielding structure of 10 cm lead followed by 10 cm borated polyethylene with a surface area of 600 $\mathrm{cm^{2}}$, deployed on top of the ISMRAN setup, is reported to be 1334 $\pm$ 64 (stat.) $\pm$ 70 (sys.) per day. This result shows good agreement with the expected background rate from MC simulations using Geant4. We also estimate the muon-induced fast-neutron rate in the ISMRAN geometry for the actual shielding configuration of 9000 $\mathrm{cm^{2}}$ surface area to be 3335 $\pm$ 160 (stat.) $\pm$ 175 (sys.) neutrons $\mathrm{day^{-1}}$ through an extrapolation, after incorporating the model dependent acceptance correction factor from the Geant4 MC simulation. Finally, using these results, we evaluate the neutron production yield due to the composite shielding in the ISMRAN geometry, which is 2.81$\times$$\mathrm{10^{-5}}$ neutrons per $\mu$ per (g/$\mathrm{cm^{2}}$) at sea level.

physics.ins-det↗

arXiv2024

Fusion of $^{7}$Li with $^{205}$Tl at near barrier energies

The complete and incomplete fusion cross sections for the $^{7}$Li+$^{205}$Tl reaction were measured at near barrier energies by online characteristic $\gamma$ ray detection technique. The complete fusion (CF) cross sections at energies above the Coulomb barrier were found to be suppressed by $\sim$ 26 \% compared to the coupled channel calculations. Reduced fusion cross sections for the present system at energies normalised to the Coulomb barrier were also found to be systematically lower than those with strongly bound projectiles forming a similar compound nucleus. The suppression observed in CF cross sections is found to be commensurate with the measured total incomplete fusion (ICF) cross sections. In the ICF cross sections, t capture is found to be dominant than $\alpha$ capture at all the measured energies. The systematic study of available CF, ICF and total fusion (TF) data with $^7$Li projectile is performed.

nucl-ex↗

arXiv2023

Sterile neutrino searches with reactor antineutrinos using coherent neutrino-nucleus scattering experiments

We present an analysis on the sensitivity to the active-sterile neutrino mixing with Germanium (Ge) and Silicon (Si) detectors in the context of the proposed coherent elastic neutrino-nucleus experiment in India. The study has been carried out with 3 (active) $+$ 1 (sterile) neutrino oscillation model. It is observed that the measurements that can be carried out with the Ge detector exhibit better sensitivity to the active-sterile neutrino mixing as compared to the Si detector. Both detectors are able to exclude most of the anomaly regions observed by the GALLIUM experiment. The Ge detector with mass 10 kg, can observe the active-sterile neutrino oscillation at 95$\%$ confidence level, provided that $\sin^{2}2\theta_{14}\geq 0.09$ at $\Delta m^{2}_{41}$ = 1.0 eV$^{2}$ for an exposure of 1-yr. At higher values of $\Delta m^{2}_{41}$, a better sensitivity is obtained at a short baseline. It is also found that the threshold as well as resolution of the detectors play a crucial role on the measurements of active-sterile neutrino mixing parameters.

hep-ph↗

arXiv2023

Background measurements and detector response studies for ISMRAN experiment

We report the measurement of the non-reactor environmental backgrounds and the detector response with the Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN), which is $\sim$1 ton detector setup by volume, consisting of 10$\times$9 (10 rows and 9 columns) Plastic Scintillator Bars (PSBs) array at BARC, Mumbai, India. ISMRAN is an above-ground anti-neutrino ($\mathrm{\overlineν_{e}}$) experiment at very short baseline located at Dhruva research reactor facility. It is enclosed by a shielding made of 10 cm thick lead and 10 cm thick borated polyethylene to minimize the backgrounds and is mounted on a movable base structure, situated at $\sim$ 13 m away from the reactor core. These measurements are useful in the context of the ISMRAN detector setup that will be used to detect the reactor $\mathrm{\overlineν_{e}}$ and measure its energy spectrum through the inverse beta decay (IBD) process. In this paper, we present the energy resolution model and energy non-linearity model of PSB and the cosmogenic muon-induced background, based on the sum of their energy depositions and number of hit bars. Reconstructed sum energy spectrum and number of hit bars distribution for $\mathrm{{}^{22}Na}$ radioactive source has been compared with Geant4 based Monte Carlo simulations. These experimentally measured results will be useful for discriminating the correlated and uncorrelated background events from the true IBD events in reactor ON and OFF conditions inside the reactor hall.

physics.ins-det↗

arXiv2022

Fusion systematics for weakly bound nuclei using neutron flow and collective degrees of freedom

A systematic analysis of the fusion cross sections around the Coulomb barrier energies with stable weakly bound ($^{6}$Li,$^{7}$Li,$^{9}$Be) and strongly bound $^{12}$C projectiles on various targets was performed by using neutron flow model and coupled channels approach. The analysis show that both the models are successful in explaining the near barrier fusion data. Further, it is also observed that the collective degrees of freedom as well as the neutron flow influence the near barrier fusion process involving weakly bound projectiles.

nucl-th↗

arXiv2022

Role of neutron transfer in the reaction mechanism of $^9$Be+$^{169}$Tm, $^{181}$Ta, $^{187}$Re and $^{197}$Au systems

The contribution of one neutron stripping cross section to the total reaction cross section has been studied for $^9$Be projectile incident on $^{169}$Tm, $^{181}$Ta, $^{187}$Re and $^{197}$Au targets around Coulomb barrier energy. The measured one neutron stripping cross sections for these systems have been compared with the coupled channel calculations. The recently developed global set of optical model potential parameters for $^9$Be projectile has been used in the present calculations. The cumulative of measured complete fusion (CF), incomplete fusion (ICF), one neutron stripping and calculated non-capture breakup (NCBU) cross sections is found to explain almost the reaction cross sections for all the targets. A very small contribution from target inelastic states and elastic breakup may contribute to the remaining part. The percentage fraction of cross section for CF, ICF, one neutron stripping, and NCBU over reaction cross section show the dominance of neutron transfer and NCBU at below barrier energies while CF and ICF processes have the major contribution at above barrier energies.

nucl-th↗

arXiv2022

Evaluation of the response of plastic scintillator bars and measurement of neutron capture time in non-reactor environment for the ISMRAN experiment

We present a detailed study on detector response to different radioactive sources and the measurements of non-reactor environmental backgrounds with the Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) detector setup consisting of 9$\times$10 Plastic Scintillator Bars (PSBs) array at BARC, Mumbai. These measurements are useful in the context of the ISMRAN detector setup, which will be used to detect the reactor anti-neutrinos (${\bar{\ensuremathν}}_{e}$) and measure its energy spectra, through the inverse beta decay (IBD) process. A GEANT4 based Monte Carlo (MC) simulation is used to understand the optical transmission, energy resolution and energy non-linearity of the ISMRAN detector. A detailed analysis procedure has been developed to understand the natural radioactive, cosmogenic and cosmic muon-induced backgrounds with the ISMRAN detector setup in a non-reactor environment, based on their energy deposition, number of bars hit as well as topological event selection criteria in position and time for triggered events. Data and MC simulated distributions of reconstructed sum energy and number of bars hit has been compared for the radioactive $γ$ + positron source such as $\mathrm{{}^{22}Na}$ placed at the center of the ISMRAN array. Fast neutron energy response and capture time distribution in ISMRAN array has been studied using a novel technique involving Time of Flight (TOF) of the measured fast neutrons. The observed characteristic neutron capture time ( $τ$ ) of 68.29 $\pm$ 9.48 $μ$s is in good agreement with $\sim$65 $μ$s obtained from MC simulation. These experimentally measured results will be useful for discriminating the correlated and uncorrelated background events from the true IBD events in reactor ON and OFF conditions inside the reactor hall.

physics.ins-det↗

arXiv2022

Cosmic ray measurements using the ISMRAN setup in a non-reactor environment

The cosmic rays data collected using a large area plastic scintillator array ISMRAN (Indian Scintillator Matrix for Reactor AntiNeutrino) are presented. The data collected serve as a useful benchmark of cosmogenic background in a non-reactor environment for the future measurements of electron-antineutrinos to be performed using the ISMRAN setup. The zenith angle distribution of the atmospheric muons has been measured and compared with Monte Carlo expectations. The detector setup was further used to measure the lifetime distribution of stopped muons and extract their rates inside the detector matrix. The measured spectra of decaying muons and associated electrons show a good agreement with the MC simulations performed through GEANT4 simulation.

nucl-ex↗

arXiv2022

Inclusive $α$ Production for $^{6}$Li+$^{51}$V System

Measurement of angular distributions and energy spectra of $α$ and deuterons through breakup, transfer and incomplete fusion processes to dis-entangle their relative contributions and to investigate relative importance of breakup-fusion compared to transfer. Inclusive $α$ production cross-sections have been measured for $^6$Li + $^{51}$V system near Coulomb barrier energies. Theoretical calculations for estimation of various reaction channels contributing to $α$ production have been performed with finite range coupled reaction method using \textsc{FRESCO} code. The cross-sections from non-capture breakup (NCBU) ($α$ + \textit{d}) and 1\textit{n}, 1\textit{p}, and 1\textit{d} transfer channels, compound nuclear decay channel and incomplete fusion (ICF) leading to $α$ production were estimated to get the cumulative production cross-sections. Contributions from breakup, transfer and incomplete fusion channels could reproduce the integral direct $α$ production cross-sections and their angular distributions quite well. The direct $α$ production cross-sections are in agreement with other targets. The $α$ production cross-sections are higher compared to the deuteron production. Kinematic analysis of the energy spectra of $α$ particles and deuterons suggest that $α$ particle spectra is dominated by breakp-fusion and deuteron spectra have contribution of breakup and transfer reactions. A systematic study of direct $α$ production with various targets follow a universal behavior on average but noticeable differences are observed for different targets. A ratio of $α$ and deuteron yields for a wide mass range of targets shows a saturation above barrier and an increasing production of $α$ particles relative to deuteron around Coulomb barrier.

nucl-ex↗

arXiv2021

Measurements using a prototype array of plastic scintillator bars for reactor based electron anti-neutrino detection

We report measurement of reactor based electron anti-neutrinos from a prototype array of plastic scintillator bars ( mini-ISMRAN ) located inside Dhruva research reactor hall, BARC. The detector setup took data for 128 days for reactor on (RON) and 51 days for reactor off (ROFF) condition. A detailed analysis procedure is developed to select the anti-neutrino candidate events based on the energy deposition, number of bars hit as well as topological event selection criteria in position and time. Each of these selection criteria are compared with Monte Carlo based simulations and further an embedding technique is used to estimate the efficiencies from a data driven background study. The obtained anti-neutrino like events in RON condition are 218 $\pm$ 50 (stat) $\pm$ 37 (sys) after background subtraction. The obtained results are compared with theoretical estimation which yields 214 $\pm$ 32 (sys) anti-neutrino events for the RON condition.

nucl-ex↗

arXiv2021

Characterization of plastic scintillator bars using fast neutrons from D-D and D-T reactions

We report results of fast neutron response in plastic scintillator (PS) bars from deuterium-deuterium (D-D) and deuterium-tritium (D-T) reactions using Purnima Neutron Generator Facility, BARC, Mumbai. These measurements are useful in context of Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) detection, an array of 10x10 PS bars, used to measure reactor anti-neutrinos through inverse beta decay (IBD) signal. ISMRAN detector, an above-ground experiment close to the reactor core (~13m), deals with an active fast neutron background inside the reactor hall. A good understanding of fast neutron response in PS bars is an essential pre-requisite for suppression and discrimination of fast neutron background from IBD events. A monoenergetic neutron beam from the fusion reaction of D-D at 2.45 MeV and D-T at 14.1 MeV are used to characterize the energy response in these bars. The neutron energy response function has been simulated using the GEANT4 package and are compared with the measured data. A reasonable agreement of deposited energies by fast neutrons in PS bars between data and simulation are obtained for these reactions. The ratio of energy deposition in adjacent bars is used to discriminate between prompt IBD, fast neutron and neutron capture cascade gamma events.

physics.ins-det↗

arXiv2021

Modeling the triple-GEM detector response to background particles for the CMS Experiment

An estimate of environmental background hit rate on triple-GEM chambers is performed using Monte Carlo (MC) simulation and compared to data taken by test chambers installed in the CMS experiment (GE1/1) during Run-2 at the Large Hadron Collider (LHC). The hit rate is measured using data collected with proton-proton collisions at 13 TeV and a luminosity of 1.5$\times10^{34}$ cm$^{-2}$ s$^{-1}$. The simulation framework uses a combination of the FLUKA and Geant4 packages to obtain the hit rate. FLUKA provides the radiation environment around the GE1/1 chambers, which is comprised of the particle flux with momentum direction and energy spectra ranging from $10^{-11}$ to $10^{4}$ MeV for neutrons, $10^{-3}$ to $10^{4}$ MeV for $γ$'s, $10^{-2}$ to $10^{4}$ MeV for $e^{\pm}$, and $10^{-1}$ to $10^{4}$ MeV for charged hadrons. Geant4 provides an estimate of detector response (sensitivity) based on an accurate description of detector geometry, material composition and interaction of particles with the various detector layers. The MC simulated hit rate is estimated as a function of the perpendicular distance from the beam line and agrees with data within the assigned uncertainties of 10-14.5%. This simulation framework can be used to obtain a reliable estimate of background rates expected at the High Luminosity LHC.

physics.ins-det↗

arXiv2021

Investigation of neutron transfer in $^{7}$Li+$^{124}$Sn reaction

The relative importance of neutron transfer and breakup process in reaction around Coulomb barrier energies have been studied for the $^{7}$Li+$^{124}$Sn system. Coupled channel calculations have been performed to understand the one neutron stripping and pickup cross sections along with the breakup in the $^{7}$Li+$^{124}$Sn system. The systematics of one and two neutron striping and pickup cross sections with $^7$Li projectile on several targets show an approximate universal behaviour that have been explained by a simple model. Complete reaction mechanism have been studied by comparing the reaction cross sections with cumulative cross sections of total fusion and one neutron transfer.

nucl-th↗

arXiv2020

Interstrip Capacitances of the Readout Board used in Large Triple-GEM Detectors for the CMS Muon Upgrade

We present analytical calculations, Finite Element Analysis modeling, and physical measurements of the interstrip capacitances for different potential strip geometries and dimensions of the readout boards for the GE2/1 triple-Gas Electron Multiplier detector in the CMS muon system upgrade. The main goal of the study is to find configurations that minimize the interstrip capacitances and consequently maximize the signal-to-noise ratio for the detector. We find agreement at the 1.5--4.8% level between the two methods of calculations and on the average at the 17% level between calculations and measurements. A configuration with halved strip lengths and doubled strip widths results in a measured 27--29% reduction over the original configuration while leaving the total number of strips unchanged. We have now adopted this design modification for all eight module types of the GE2/1 detector and will produce the final detector with this new strip design.

physics.ins-det↗

arXiv2020

Measuring Mars Atmospheric Winds From Orbit

Wind is the process that connects Mars' climate system. Measurements of Mars atmospheric winds from orbit would dramatically advance our understanding of Mars and help prepare for human exploration of the Red Planet. Multiple instrument candidates are in development and will be ready for flight in the next decade. We urge the Decadal Survey to make these measurements a priority for 2023-2032.

astro-ph.IM↗

arXiv2020

Systematics of direct-$α$ production with weakly and strongly bound projectiles

The production of $α$-particles in reactions using both the strongly and weakly bound projectiles at energies around the Coulomb barrier show several interesting features. To understand these, the role of various reaction mechanisms responsible for $α$-production, such as non-capture breakup, capture of only one of the fragments subsequent to projectile breakup and their contribution to reaction cross sections have been investigated. A systematic study of the $α$-particle production based on available data for various projectile target systems have been performed and a classification based on projectile type is obtained.

nucl-ex↗