arXiv subjects

M. Chaudhuri

Publications and source records attributed to M. Chaudhuri.

33 records · Page 2Linked to original sources

arXiv2022

Large-mass, low-threshold sapphire detector for rare event searches

Low mass nuclear recoil dark matter and coherent-elastic-neutrino-nucleus-scattering (CENNS) searches confront similar challenges in choosing ultra-low threshold and large-mass detectors. We report experimental results from the first-of-its-kind 100 g single-crystal sapphire detector design with a diameter of 76 mm and thickness of 4 mm. The detector is designed to be sensitive for low-energy rare interactions with an intention to investigate the low mass region of dark matter phase-space and search for CENNS at the reactor site. Sapphire is a crystal of aluminum oxide (Al2O3) and has been found to be a good candidate for light mass spin-dependent dark matter search experiments due to its lower atomic mass compared to other detector materials such as germanium and silicon. Using the data collected from the test facility at Texas A&M University, we were able to resolve low energy lines from calibration sources and estimated that our newly developed sapphire detector has a baseline recoil energy resolution of 18 eV. These detectors are operated at 0 V with the phonon-assisted detection providing a quenching-free low-threshold operation.

physics.ins-det↗

arXiv2022

EXCESS workshop: Descriptions of rising low-energy spectra

Many low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was initiated. In its first iteration in June 2021, ten rare event search collaborations contributed to this initiative via talks and discussions. The contributing collaborations were CONNIE, CRESST, DAMIC, EDELWEISS, MINER, NEWS-G, NUCLEUS, RICOCHET, SENSEI and SuperCDMS. They presented data about their observed energy spectra and known backgrounds together with details about the respective measurements. In this paper, we summarize the presented information and give a comprehensive overview of the similarities and differences between the distinct measurements. The provided data is furthermore publicly available on the workshop's data repository together with a plotting tool for visualization.

astro-ph.IM↗

arXiv2022

A novel active veto prototype detector with an inner target for improved rare event searches

We report the fabrication and performance of an annular, cryogenic, phonon-mediated veto detector that can host an inner target detector, allowing substantial reduction in radiogenic backgrounds for rare event search experiments. A germanium veto detector of mass $\sim$500 g with an outer diameter of 76 mm and an inner diameter of 28 mm was produced. A 25 mm diameter germanium inner target detector of mass $\sim$10 g was mounted inside the veto detector. The detector was designed using inputs from a GEANT4 based simulation, where it was modeled to be sandwiched between two germanium detectors. The simulation showed that the background rates (dominantly gamma interactions) could be reduced by $>$ 90$\%$, and that such an arrangement is sufficient for aggressive background reduction needed for neutrino and dark matter search experiments. During testing at the experimental site the veto detector prototype achieved a baseline resolution of 1.24 $\pm$ 0.02 keV while hosting a functional inner target detector. The baseline resolution of the inner target detector was 147 $\pm$ 2 eV. The detectors were operated at mK temperatures. The experimental results of an identical detector arrangement are in excellent agreement with the simulation.

physics.ins-det↗

arXiv2022

Constraints on Lightly Ionizing Particles from CDMSlite

The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) achieved efficient detection of very small recoil energies in its germanium target, resulting in sensitivity to Lightly Ionizing Particles (LIPs) in a previously unexplored region of charge, mass, and velocity parameter space. We report first direct-detection limits calculated using the optimum interval method on the vertical intensity of cosmogenically-produced LIPs with an electric charge smaller than $e/(3\times10^5$), as well as the strongest limits for charge $\leq e/160$, with a minimum vertical intensity of $1.36\times10^{-7}$\,cm$^{-2}$s$^{-1}$sr$^{-1}$ at charge $e/160$. These results apply over a wide range of LIP masses (5\,MeV/$c^2$ to 100\,TeV/$c^2$) and cover a wide range of $βγ$ values (0.1 -- $10^6$), thus excluding non-relativistic LIPs with $βγ$ as small as 0.1 for the first time.

hep-ex↗

arXiv2021

Electron drag force in EUV induced pulsed hydrogen plasmas

Extreme ultraviolet (EUV) induced pulsed plasma is unique due to its transient characteristics: the plasma switches between non-thermal state (when EUV power is ON at the beginning of the pulse) and thermal state (end of the pulse at ~ 20 us). It is shown that although electron drag force acting on nm size particles in hydrogen plasma is negligible compared to the ion drag force at the beginning of the pulse, however it can be dominant at the end of the pulse and can play important role in particle transport leading to defectivity issues for semiconductor chip production technologies.

physics.plasm-ph↗

arXiv2021

Light Dark Matter Search with a High-Resolution Athermal Phonon Detector Operated Above Ground

We present limits on spin-independent dark matter-nucleon interactions using a $10.6$ $\mathrm{g}$ Si athermal phonon detector with a baseline energy resolution of $σ_E=3.86 \pm 0.04$ $(\mathrm{stat.})^{+0.19}_{-0.00}$ $(\mathrm{syst.})$ $\mathrm{eV}$. This exclusion analysis sets the most stringent dark matter-nucleon scattering cross-section limits achieved by a cryogenic detector for dark matter particle masses from $93$ to $140$ $\mathrm{MeV}/c^2$, with a raw exposure of $9.9$ $\mathrm{g}\cdot\mathrm{d}$ acquired at an above-ground facility. This work illustrates the scientific potential of detectors with athermal phonon sensors with eV-scale energy resolution for future dark matter searches.

hep-ex↗

arXiv2017

Triple junction at the triple point resolved on the individual particle level

At the triple point of a repulsive screened Coulomb system, a face-centered-cubic (fcc) crystal, a body-centered-cubic (bcc) crystal and a fluid phase coexist. At their intersection, these three phases form a liquid groove, the triple junction. Using confocal microscopy, we resolve the triple junction on a single particle level in a model system of charged PMMA colloids in a nonpolar solvent. The groove is found to be extremely deep and the incommensurate solid-solid interface to be very broad. Thermal fluctuations hence appear to dominate the solid-solid interface. This indicates a very low interfacial energy. The fcc-bcc interfacial energy is quantitatively determined based on Young's equation and, indeed, it is only about 1.3 times higher than the fcc-fluid interfacial energy close to the triple point.

cond-mat.soft↗

arXiv2016

Dust interferometers in plasmas

An interferometric imaging technique has been proposed to instantly measure the diameter of individual spherical dust particles suspended in a gas discharge plasma. The technique is based on the defocused image analysis of both spherical particles and their binary agglomerates. Above a critical diameter, the defocused images of spherical particles contain stationary interference fringe patterns and the fringe number increases with particle diameters. Below this critical diameter, the particle size has been measured using the rotational interference fringe patterns which appear only on the defocused images of binary agglomerates. In this case, a lower cut-off limit of particle diameter has been predicted, below which no such rotational fringe patterns are observed for the binary agglomerates. The method can be useful as a diagnostics for complex plasma experiments on earth as well as under microgravity condition.

physics.plasm-ph↗

arXiv2015

Quasi-two-dimensional complex plasma containing spherical particles and their binary agglomerates

A new type of quasi-two-dimensional complex plasma system was observed which consisted of monodisperse microspheres and their binary agglomerations (dimers). The particles and their dimers levitated in a plasma sheath at slightly different heights and formed two distinct sublayers. The sys- tem did not crystallize and may be characterized as disordered solid. The dimers were identified based on their characteristic appearance in defocused images, i.e., rotating interference fringe pat- terns. The in-plane and inter-plane particle separations exhibit nonmonotonic dependence on the discharge pressure which agrees well with theoretical predictions.

physics.plasm-ph↗

arXiv2014

Transpose-free Fast Fourier Transform for Turbulence Simulation

Pseudo-spectral method is one of the most accurate techniques for simulating turbulent flows. Fast Fourier transform (FFT) is an integral part of this method. In this paper, we present a new procedure to compute FFT in which we save operations during interprocess communications by avoiding transpose of the array. As a result, our transpose-free FFT is 15\% to 20\% faster than FFTW.

cs.MS↗

arXiv2013

Nonlinear Shear Wave in a Non Newtonian Visco-elastic Medium

An analysis of nonlinear transverse shear wave has been carried out on non-Newtonian viscoelastic liquid using generalized hydrodynamic(GH) model. The nonlinear viscoelastic behavior is introduced through velocity shear dependence of viscosity coefficient by well known Carreau -Bird model. The dynamical feature of this shear wave leads to the celebrated Fermi-Pasta-Ulam (FPU) problem. Numerical solution has been obtained which shows that initial periodic solutions reoccur after passing through several patterns of periodic waves. A possible explanation for this periodic solution is given by constructing modified Korteweg de Vries (mKdV) equation. This model has application from laboratory to astrophysical plasmas as well as biological systems.

physics.plasm-ph↗

arXiv2013

Viscosity gradient driven instability of `shear mode' in a strongly coupled plasma

The influence of viscosity gradient (due to shear flow) on low frequency collective modes in strongly coupled dusty plasma is analyzed. It is shown that for a well known viscoelastic plasma model, the velocity shear dependent viscosity leads to an instability of the shear mode. The inhomogeneous viscous force and velocity shear coupling supply the free energy for the instability. The combined strength of shear flow and viscosity gradient wins over any stabilizing force and makes the shear mode unstable. Implication of such a novel instability and its applications are briefly outlined.

physics.plasm-ph↗

arXiv2013

Particle flows in a dc discharge in laboratory and microgravity conditions

We describe a series of experiments on dust particles flows in a positive column of a horizontal dc discharge operating in laboratory and microgravity conditions. The main observation is that the particle flow velocities in laboratory experiments are systematically higher than in microgravity experiments, for otherwise identical discharge conditions. The paper provides an explanation for this interesting and unexpected observation. The explanation is based on a physical model, which properly takes into account main plasma-particle interaction mechanisms relevant to the described experimental study. Comparison of experimentally measured particle velocities and those calculated using the proposed model demonstrates reasonable agreement, both in laboratory and microgravity conditions, in the entire range of discharge parameters investigated.

physics.plasm-ph↗

arXiv2012

Direct experimental observation of binary agglomerates in complex plasmas

A defocusing imaging technique has been used as a diagnostic to identify binary agglomerates (dimers) in complex plasmas. Quasi-two-dimensional plasma crystal consisting of monodisperse spheres and binary agglomerates has been created where the agglomerated particles levitate just below the spherical particles without forming vertical pairs. Unlike spherical particles, the defocused images of binary agglomerates show distinct, stationary/periodically rotating interference fringe patterns. The results can be of fundamental importance for future experiments on complex plasmas.

physics.plasm-ph↗

arXiv2010

Effect of ionization/recombination processes on the electrical interactions between positively charged particles in highly collisional plasmas

The effect of ionization and recombination processes on the electrical interactions between a pair of small charged particles in highly collisional plasmas is discussed. In particular, it is shown that these processes suppress the long-range attraction between positively charged particles. The condition corresponding to the vanishing of attraction is derived. The role of the effect for conditions of existing experiments is estimated.

physics.plasm-ph↗