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Purba Bhattacharya

Publications and source records attributed to Purba Bhattacharya.

At least 19 recordsLinked to original sources
arXiv2026

neBEM: A GPU-accelerated Electrostatic Field Solver

Accurate electric field estimation is critical for the design and optimization of Micro Pattern Gaseous Detectors (MPGDs). The nearly exact Boundary Element Method (neBEM) offers high precision field computation but is limited by long CPU runtime arising from its complex analytical formulations. This work presents a comprehensive optimization of the neBEM solver, focusing on a hybrid hardware acceleration strategy using OpenMP for multi-core CPUs and GPU acceleration using NVIDIA's CUDA. A key contribution is the new implementation of a dynamic space charge calculation, which has also been designed to be accelerated by CUDA. This primary acceleration is complemented by enhanced algorithmic optimizations to reduce the complexity of the problem. The proposed implementation achieves substantial speedups while preserving inherent accuracy of the solver. Simulations on staggered thick Gas Electron Multiplier geometries demonstrate agreement with other commercially available field solvers, verifying the fidelity of accelerated neBEM. Benchmarking tests show a significant speedup, enabling rapid yet precise simulations for complex MPGD configurations. These improvements make GPU-accelerated neBEM a practical tool for large-scale detector simulation.

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arXiv2025

Application of muon absorption tomography in imaging of civil structures

The research focuses on the non-invasive imaging technique using cosmic muon absorption tomography to monitor the internals of archaeological / civil / industrial structures of intermediate size. It integrates experimental measurements and numerical simulations with Geant4, ascertaining the reliability and precision of muon absorption tomography using easily available components for the stated purpose. The experiment probes muon interactions across a range of materials including those commonly used in building civil and industrial structures. An experiment, fondly named MARS (Muon Absorption in Rigid Structures), was carried out to explore the possibility of using overlapped scintillation paddles for improved mapping of inhomogeneities in structures made of concrete. Good correlation of experimental and simulated results for all tests indicates that this simple approach can be implemented for non-destructive evaluations of structures of civil and industrial interest

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arXiv2025

Signal Formation in THGEM-like Detectors

Numerical simulations were used to study signal formation in a Thick Gaseous Electron Multiplier (THGEM) and in THGEM -based Thick-WELL (THWELL) and Resistive-Plate WELL (RPWELL) detectors. The signal shapes were simulated in mixtures of Argon and Neon with $5\%$ Methane under irradiation with soft x-rays and muons. Anode-induced raw signals were convoluted with the response functions of charge-sensitive and current-sensitive pre-amplifiers. The simulation toolkit was validated by the good agreement reached between the simulated and measured response, with different pre-amplifiers. It indicates that our simulations framework provides valid insight into the inherent complex dynamical processes of the various detectors.

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arXiv2024

Numerical simulation of charging up, accumulation of space charge and formation of discharges

Aging and stability of gaseous ionization detectors are intricately related to charging up, accumulation of space charge and formation of discharges. All these phenomena, in their turn, depend on the dynamics of charged particles within the device. Because of the large number of particles involved and their complex interactions, the dynamic processes of generation and loss of charged particles, and their transport within the detector volume are extremely expensive to simulate numerically. In this work, we propose and evaluate possible algorithms / approaches that show some promise in relation to the above-mentioned problems. Several important ionization detectors having parallel plate configurations, such as GEM, Micromegas, RPCs and THGEMs, are considered for this purpose. Information related to primary ionization is obtained from HEED, while all the transport properties are evaluated using MAGBOLTZ. The transport dynamics have been followed using two different approaches. In one, particle description using neBEM-Garfield++ combination has been used. For this purpose, the neBEM solver has been significantly improved such that perturbations due to the charged particles present within the device are considered while estimating electric field. In the other approach, the transport is simulated following hydrodynamic model using COMSOL during which the electric field is also provided by COMSOL where it is easy to set up space charge effects. A comparison between these possible approaches will be presented. Effect of different simulation parameters will also be demonstrated using simple examples.

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arXiv2024

Effect of hole geometry on charge sharing and other parameters in GEM-based detectors

Gas Electron Multipliers (GEM) are among the more prominent Micro-Pattern Gaseous Detectors (MPGDs) and widely used in high energy particle physics experiments and various related applications. Adoption of different production techniques lead to holes of varying geometries in GEM foils. Since the response of a GEM-based detector is closely related to the hole geometry through the influence of the latter on charge sharing and transport through GEM foils, attempts have been made to relate hole configurations to different figures of merit of a detector. Numerical simulations have been performed to study the effects of hole geometry on important parameters such as charge sharing, collection efficiency, extraction efficiency, gain, possibility of transition from avalanche to streamer modes for single, double and triple layer GEM detectors. The numerical estimates have been compared to available experimental data. The comparisons, although not always in agreement, are found to be generally encouraging.

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arXiv2023

Parallelization of Garfield++ and neBEM to simulate space charge effects in RPCs

Numerical simulation of avalanches, saturated avalanches, and streamers can help us understand the detector physics of Resistive Plate Chambers (RPC). 3D Monte Carlo simulation of an avalanche inside an RPC, the transition from avalanche to saturated avalanche to streamer may help the search for the optimum voltage and alternate gas mixtures. This task is dauntingly resource-hungry, especially when space charge effects become important, which often coincides with important regimes of operation of these devices. By modifying the electric field inside the RPC dynamically, the space charge plays a crucial role in determining the response of the detector. In this work, a numerical model has been proposed to calculate the dynamic space-charge field inside an RPC and the same has been implemented in the Garfield++ framework. By modeling space charge as the large number of line charges and using the multithreading technique OpenMP to calculate electric field, drift line, electron gain, and space charge field, it has been possible to maintain time consumption within reasonable limits. For this purpose, a new class, pAvalancheMC has been introduced in Garfield++. The calculations have been successfully verified with those from existing solvers and an example is provided to show the performance of pAvalancheMC. Moreover, the details of the transition of an avalanche into a saturated avalanche have been discussed. The induced charge distribution is calculated for a timing RPC and results are verified with the experiment.

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arXiv2022

Design and studies of thick Gas Electron Multipliers fabricated in India

THick Gas Electron Multipliers (THGEMs) are robust and high gain Micro Pattern Gaseous Detectors which are economically manufactured by standard drilling and etching of thin printed circuit boards. In this paper, we present our recent simulation as well as experimental studies on THGEMs which have been fabricated in India using local expertise. Two types of THGEMs have been fabricated; one set has holes without any external rim and another set has holes with rims. These detectors have been characterized using argon-carbon dioxide and argon-isobutane gas mixtures. Electron transmission, effective gain, energy resolution and optimized working range studies have been presented for both the sets of THGEMs.

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arXiv2022

Double-hit separation and dE/dx resolution of a time projection chamber with GEM readout

A time projection chamber (TPC) with micropattern gaseous detector (MPGD) readout is investigated as main tracking device of the International Large Detector (ILD) concept at the planned International Linear Collider (ILC). A prototype TPC equipped with a triple gas electron multiplier (GEM) readout has been built and operated in an electron test beam. The TPC was placed in a 1 T solenoidal field at the DESY II Test Beam Facility, which provides an electron beam up to 6 GeV/c. The performance of the readout modules, in particular the spatial point resolution, is determined and compared to earlier tests. New studies are presented with first results on the separation of close-by tracks and the capability of the system to measure the specific energy loss dE/dx. This is complemented by a simulation study on the optimization of the readout granularity to improve particle identification by dE/dx.

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arXiv2022

Test-Beam and Simulation Studies Towards RPWELL-based DHCAL

Digital Hadronic Calorimeters (DHCAL) were suggested for future Colliders as part of the particle-flow concept. Though studied mainly with Resistive Plate Chambers (RPC), studies focusing on Micro-Pattern Gaseous Detector (MPGD)-based sampling elements have shown the potential advantages; they can be operated with environmental friendly gases and reach similar detection efficiency at lower average pad-multiplicity. We summarize here the experimental test-beam results of a small-size DHCAL prototype, incorporating six Micromegas (MM) and two Resistive-Plate WELL (RPWELL) sampling elements, interlaced with steel-absorber plates. It was investigated with 2-6 GeV pion beam at the CERN/PS beam facility. The data permitted validating a GEANT4 simulation framework of a DHCAL, and evaluating the expected pion energy resolution of a full-scale RPWELL-based calorimeter. The pion energy resolution of $\fracσ{E[GeV]}=\frac{50.8\%}{\sqrt{E[GeV]}} \oplus 10.3\%$ derived expected with the RPWELL concept is competitive to that of glass RPC and MM sampling techniques.

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arXiv2022

Study of space charge phenomena in GEM-based detectors

Space charge accumulation within GEM holes is one of the vital phenomena which affects many of the key working parameters of the detector. This accumulation is found to be significantly affected by the initial primary charge configurations and applied GEM voltages since they determine charge sharing and the subsequent evolution of detector response. In this work, we have studied the effects of space charge phenomena on different parameters for single GEM detectors using a hybrid numerical model.

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arXiv2021

Numerical estimation of discharge probability in GEM-based detectors

Discharge probability in GEM-based gaseous detectors has been numerically estimated using an axisymmetric hydrodynamic model. Initial primary charge configurations in the drift region, obtained using Heed and Geant4, are found to have significant effect on the subsequent evolution of detector response. Simulation of energy resolution has been performed to establish the capability of the hydrodynamic model to capture statistical nature of the experimental situation. Finally, single and triple GEM configurations exposed to alpha sources have been simulated to estimate discharge probability which have been compared with available experimental data. Despite the simplifying and drastic assumptions in the numerical model, the comparisons are encouraging.

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arXiv2021

Single Electron Spectra in RPWELL-based detectors

Single-electron avalanche distributions in gaseous multipliers affect their efficient detection and that of single UV-photons. In this work, we investigated the shape of single-photo-electron spectra in single- and double-stage Resistive Plate WELL (RPWELL) detector configurations, operated in $\mathrm{Ne/CH_{4}}$ and $\mathrm{Ar/CH_{4}}$. Discharge-free operation was reached over a broad dynamic range, with charge gains of \numrange[range-phrase = -]{e4}{e6}. Compared to the usual exponential ones, the observed Polya-like charge spectra pave the way towards higher single-electrons detection efficiencies. The latter were evaluated here, using experimental data combined with numerical simulations. The effects of the gas mixtures, electric field configuration and detector geometry on the Polya spectra and their related "$θ$" parameter are presented.

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arXiv2020

Fast simulation of avalanche and streamer in GEM detector using hydrodynamic approach

A fast, hydrodynamic numerical model has been developed on the COMSOL Multi-physics platform to simulate the evolution and dynamics of charged particles in gaseous ionization detectors based on the Gaseous Electron Multipliers (GEM). Effects of using two-dimensional (2D), 2D axisymmetric and three-dimensional(3D) models of the detectors have been analyzed to choose the optimum configuration. The chosen model has been used to follow the entire operating regime of single, double and triple GEM detectors, including avalanche and streamer mode operations. The accumulation of space charge, its contribution towards the distortion of the applied electric field and production of streamers have been investigated in fair detail using the optimized model.

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arXiv2020

Studies on charging-up of single Gas Electron Multiplier

Mechanisms of charging-up and charging-down of Gas Electron Multiplier (GEM) have been studied. Experimental investigations have been carried out on both dielectric polarization and radiation charging of GEMs. Environmental parameters, such as pressure and temperature have been monitored to normalize their effects on the charging-up and charging-down measurements. Variation in gain due to the combined, as well as individual, effects of the mentioned parameters has been illustrated.

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arXiv2020

Numerical study of track distortion in the Large Prototype TPC with end-plate based on bulk Micromegas

The present $\mathrm{R}\&\mathrm{D}$ activities for the International Large Detector Time Projection Chamber (ILD-TPC) concern the adoption of the micro pattern devices for the gaseous amplification stage. Seven Micromegas modules which are commissioned on the end-plate of a Large Prototype TPC (LPTPC) at DESY, were tested with a 5 GeV electron beam, under a 1 T magnetic field. During experiments, reduced signal sensitivity as well as distortion in the reconstructed track was observed at the boundaries of these modules. Electrostatic field inhomogeneity near the module boundaries was considered to be the possible major reason behind these observations. In the present work, this hypothesis has been explored using the Garfield simulation framework. It has been possible to contain the computational complexity of the problem with suitable simplifications. Qualitative and quantitative agreements with experimental results have been achieved. Possibility of mitigating the problems has been proposed using the same simulation framework.

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arXiv2020

Charge sharing in single and double GEMs

The Gas Electron Multiplier (GEM) has become a widely used technology for high-rate particle physics experiments like COMPASS, LHCb and are being used as the readout system for the upcoming upgrade version of other experiments such as ALICE TPC. Radiation hardness, ageing resistance and stability against discharges are main criteria for long-term operation of such detectors in high-rate experiments. In particular, discharge is a serious issue as it may cause irreversible damages to the detector as well as the readout electronics. The charge density inside the amplification region is the limiting factor for detector stability against discharges. By using multiple devices and thus, sharing the electron multiplication in different stages, maximum sustainable gain can be increased by several orders of magnitude. A common explanation for this is connected to the transverse electron diffusion, widening of the electron cloud and reducing the charge density in the last multiplier. However, this has not been verified yet. In our work, we are using Garfield simulation framework as a tool to extract the information related to the transverse size of the propagating electron cloud and thus, to estimate the charge density in the GEM holes for multiple stages. For a given gas mixture, we will present the initial results of charge sharing using single and double GEM detectors under different electric field configurations and its effect on other measurable detector parameters such as single point position resolution.

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arXiv2017

Experimental and numerical simulation of a TPC like set up for the measurement of ion backflow

Ion backflow is one of the effects limiting the operation of a gaseous detector at high flux, by giving rise to space charge which perturbs the electric field. The natural ability of bulk Micromegas to suppress ion feedback is very effective and can help the TPC drift volume to remain relatively free of space charge build-up. An efficient and precise measurement of the backflow fraction is necessary to cope up with the track distortion due to the space charge effect. In a subtle but significant modification of the usual approach, we have made use of two drift meshes in order to measure the ion backflow fraction for bulk Micromegas detector. This helps to truly represent the backflow fraction for a TPC. Moreover, attempt is taken to optimize the field configuration between the drift meshes. In conjunction with the experimental measurement, Garfield simulation framework has been used to simulate the related physics processes numerically.

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