Saikat Karmakar

We investigate exotic neutrino interactions using the 205.4 kg$\cdot$day dataset from the CDEX-10 experiment at the China Jinping Underground Laboratory. New constraints on the mass and couplings of new gauge bosons are presented. Two nonstandard neutrino interactions are considered: a $U(1)_{B-L}$ gauge-boson-induced interaction between an active neutrino and electron/nucleus, and a dark-photon-induced interaction between a sterile neutrino and electron/nucleus via kinetic mixing with a photon. This work probes an unexplored parameter space involving sterile neutrino coupling with a dark photon. New laboratory limits are derived on dark photon masses below $1~{\rm eV}/c^{2}$ at some benchmark values of $\Delta m_{41}^{2}$ and $g^{\prime2}{\rm{sin}}^{2}2\theta_{14}$.

The low energy coherent neutrino-nucleus elastic scattering is being studied in a number of experimental programs around the world. As part of TEXONO's neutrino research program at Kuo-Sheng nuclear power plant, state-of-art high purity point-contact Germanium detectors with $\mathcal{O}{(100}$~eV) threshold are utilized to study such low energy neutrino interactions at the complete coherency regime. This work will provide an overview of current coherent neutrino-nucleus elastic scattering activities and recent results at the TEXONO experiment. We will also discuss the quantitative studies of quantum-mechanical coherency effects in coherent neutrino-nucleus elastic scattering.

Recently a dark matter-electron (DM-electron) paradigm has drawn much attention. Models beyond the standard halo model describing DM accelerated by high energy celestial bodies are under intense examination as well. In this Letter, a velocity components analysis (VCA) method dedicated to swift analysis of accelerated DM-electron interactions via semiconductor detectors is proposed and the first HPGe detector-based accelerated DM-electron analysis is realized. Utilizing the method, the first germanium based constraint on sub-GeV solar reflected DM-electron interaction is presented with the 205.4 kg·day dataset from the CDEX-10 experiment. In the heavy mediator scenario, our result excels in the mass range of 5-15 keV/c^{2}, achieving a 3 orders of magnitude improvement comparing with previous semiconductor experiments. In the light mediator scenario, the strongest laboratory constraint for DM lighter than 0.1 MeV/c^{2} is presented. The result proves the feasibility and demonstrates the vast potential of the VCA technique in future accelerated DM-electron analyses with semiconductor detectors.

Purpose: Radiologists are tasked with visually scrutinizing large amounts of data produced by 3D volumetric imaging modalities. Small signals can go unnoticed during the 3d search because they are hard to detect in the visual periphery. Recent advances in machine learning and computer vision have led to effective computer-aided detection (CADe) support systems with the potential to mitigate perceptual errors. Approach: Sixteen non-expert observers searched through digital breast tomosynthesis (DBT) phantoms and single cross-sectional slices of the DBT phantoms. The 3D/2D searches occurred with and without a convolutional neural network (CNN)-based CADe support system. The model provided observers with bounding boxes superimposed on the image stimuli while they looked for a small microcalcification signal and a large mass signal. Eye gaze positions were recorded and correlated with changes in the area under the ROC curve (AUC). Results: The CNN-CADe improved the 3D search for the small microcalcification signal (delta AUC = 0.098, p = 0.0002) and the 2D search for the large mass signal (delta AUC = 0.076, p = 0.002). The CNN-CADe benefit in 3D for the small signal was markedly greater than in 2D (delta delta AUC = 0.066, p = 0.035). Analysis of individual differences suggests that those who explored the least with eye movements benefited the most from the CNN-CADe (r = -0.528, p = 0.036). However, for the large signal, the 2D benefit was not significantly greater than the 3D benefit (delta delta AUC = 0.033, p = 0.133). Conclusion: The CNN-CADe brings unique performance benefits to the 3D (vs. 2D) search of small signals by reducing errors caused by the under-exploration of the volumetric data.

We introduce the DREAMS project, an innovative approach to understanding the astrophysical implications of alternative dark matter models and their effects on galaxy formation and evolution. The DREAMS project will ultimately comprise thousands of cosmological hydrodynamic simulations that simultaneously vary over dark matter physics, astrophysics, and cosmology in modeling a range of systems -- from galaxy clusters to ultra-faint satellites. Such extensive simulation suites can provide adequate training sets for machine-learning-based analyses. This paper introduces two new cosmological hydrodynamical suites of Warm Dark Matter, each comprised of 1024 simulations generated using the Arepo code. One suite consists of uniform-box simulations covering a $(25~h^{-1}~{\rm M}_\odot)^3$ volume, while the other consists of Milky Way zoom-ins with sufficient resolution to capture the properties of classical satellites. For each simulation, the Warm Dark Matter particle mass is varied along with the initial density field and several parameters controlling the strength of baryonic feedback within the IllustrisTNG model. We provide two examples, separately utilizing emulators and Convolutional Neural Networks, to demonstrate how such simulation suites can be used to disentangle the effects of dark matter and baryonic physics on galactic properties. The DREAMS project can be extended further to include different dark matter models, galaxy formation physics, and astrophysical targets. In this way, it will provide an unparalleled opportunity to characterize uncertainties on predictions for small-scale observables, leading to robust predictions for testing the particle physics nature of dark matter on these scales.

Bound states of complex scalar fields (boson stars) have long been proposed as possible candidates for the dark matter in the universe. Considerable work has already been done to study various aspects of boson stars. In the present work, assuming a particular anisotropic matter distribution, we solve the Einstein-Klein-Gordon equations with a cosmological constant to obtain bosonic configurations by treating the problem geometrically. The results are then applied to problems covering a wide range of masses and radii of the boson stars and the relevant self interaction parameters are calculated. We compare our results with earlier treatments to show the applicability of the geometrical approach.

A search for exotic dark matter (DM) in the sub-GeV mass range has been conducted using 205 kg day data taken from a p-type point contact germanium detector of the CDEX-10 experiment at China's Jinping underground laboratory.New low-mass dark matter searching channels, neutral current fermionic DM absorption, have been analyzed with an energy threshold of 160 eVee.No significant signal was found; thus new limits on the DM-nucleon interaction cross section are set for both models at the sub-GeV DM mass region.A cross section limit for the fermionic DM absorption is set to be 2.5 × 10 -46 cm 2 (90% C.L.) at DM mass of 10 MeV=c 2 .For the DM-nucleus 3 → 2 scattering scenario, limits are extended to DM mass of 5 and 14 MeV=c 2 for the massless dark photon and bound DM final state, respectively.

The major drawback of Modular Multilevel Converter (MMC) based variable speed drives is that the capacitor voltage ripple varies inversely with the output frequency. This voltage ripple can be reduced at lower operating frequency by injecting circulating current into its each arm. However, this circulating current increases the overall current rating of the converter. The voltage ripple can also be reduced by reducing the dc bus voltage when the drive is required to be operated at lower speeds. In this paper, a new configuration using multipulse diode bridge rectifier is proposed to reduce the dc bus voltage when the drive is operated at lower speeds. Therefore, the capacitor ripple voltage is reduced without injecting any circulating current. The proposed configuration is simulated in MATLAB/Simulink and the simulation results are presented to validate the proposed configuration.

Cascaded multicell converter (CMC) is proved to be an effective solution for medium voltage drives. Three-phase diode bridge rectifiers are normally used in this converter, which do not have regeneration capability. Pulsewidth-modulated (PWM) rectifier-based power cells enable the drives with regeneration capability. However, due to their two-level voltage operation at the input side, an inductor is required for each cell to filter out the switching frequency components from the input current. In this paper, a new configuration with single-phase PWM rectifier-based power cell is proposed to achieve multilevel voltage operation at both the input and output sides of the converter. Therefore, the devices at the rectifier side are also operated at reduced switching frequency without using any filter inductor for each cell. In the proposed converter, simple modular transformers are used instead of a single large and complex transformer that is used in the conventional CMC. Further, input phase currents of the converter are controlled in the synchronously rotating d-q frame, which requires only two current sensors at the input side instead of individual current sensors for each cell. Experimental validation of the proposed converter configuration is carried out on a 4.5-kVA prototype, and the results are presented.

India-based Neutrino Observatory (INO) [1] has proposed construction of a 50k ton magnetised Iron Calorimeter (ICAL) in an underground laboratory located in South India. Main aims of this, now funded project are to precisely study the atmospheric neutrino oscillation parameters and to determine the ordering of neutrino masses [2]. The detector will deploy about 28,800 glass Resistive Plate Chambers (RPCs) of approximately 2 m × 2 m in area. An ICAL RPC detector with a signal pick-up strip pitch of 30 mm, will have 128 analog signals to be readout and processed - 64 each of positive and negative polarity signals. Thus about 3.6 million detector channels are required to be instrumented. We will present in this paper, design of electronics, trigger and data acquisition systems of this ambitious and indigenous experiment as well as its current status of deployment.

In this recent work, we present the characteristic of the emission of the black particles ejected with [Formula: see text] [Formula: see text] [Formula: see text] and [Formula: see text] [Formula: see text][Formula: see text] i.e., in the forward and backward hemispheres, respectively. For the multiplicity variation study of black particles, we have considered the interaction of [Formula: see text]Kr beam with the CNO, AgBr target present in the nuclear emulsion detector. After doing the analysis of the data, we have found that the emission possibility of black particle is greater in the forward hemisphere (FHS) angle whereas in the backward hemisphere (BHS) angle, it is quite low. Along with this, we have also found that the emission probability of black particles does not posses any relation with projectile mass as well as with the incident energy. In this work, we have also studied the characteristics of shower and et al. particles using a new parameter Q (total charge [Formula: see text] of the outgoing projectile fragments emitted in forward cone [Formula: see text], here Z denotes charge, and PF denotes Projectile Fragment) instead of impact parameter to distinguish the different type of collision for two interacting nuclei. The observation from this study suggests that the emission probability of the shower particles as well as gray particles increase as the value of Q decreasing (i.e., as we move from peripheral to central colisions). The results of this work are also compared with the context of other experimental observations and it seems to be relevant.

The traditional way of SUSY searches generally involve high missing transverse momentum because of the presence of the lightest supersymmetric particle (LSP), which is stable and remains undetected.This kind of SUSY models are called R-parity conserving SUSY.But there is also alternative scenario, where the LSP is not stable any more and can decays to Standard Model particles.This is possible in R-parity violating SUSY models.In this report three such SUSY searches have been presented.From CMS, search for top squark pair production in events with two top quark and additional jets are reported.In this analysis Top squark masses up to 670 (870) GeV are excluded at 95% confidence level for the RPV (stealth) scenario.From ATLAS, a search for R-parity-violating supersymmetry in final states characterized by high jet multiplicity, at least one isolated light lepton and either zero or at least three b-tagged jets is presented.No significant excess over the Standard Model expectation is observed and exclusion limits at the 95% confidence level are extracted, reaching as high as 2.4 TeV in gluino mass, 1.35 TeV in top-squark mass, and 320 (365) GeV in higgsino (wino) mass.From LHCb, a search is performed for massive long-lived particles (LLP) decaying semileptonically into a muon and two quarks.No evidence of these long-lived states has been observed, and upper limits on the production cross-section times branching ratio have been set for each model considered.

CDEX-50 is a next-generation project of the China Dark Matter Experiment (CDEX) that aims to search for dark matter using a 50-kg germanium detector array. This paper comprises a thorough summary of the CDEX-50 experiment, including an investigation of potential background sources and the development of a background model. Based on the baseline model, the projected sensitivity of weakly interacting massive particle (WIMP) is also presented. The expected background level within the energy region of interest, set to 2--2.5 keVee, is $\sim$0.01 counts keVee$^{-1}$ kg$^{-1}$ day$^{-1}$. At 90\% confidence level, the expected sensitivity to spin-independent WIMP-nucleon couplings is estimated to reach a cross-section of 5.3 $\times$ 10$^{-45}$ cm$^{2}$ for a WIMP mass of 5 GeV/c$^{2}$ with an exposure objective of 150 kg$\cdot$year and an analysis threshold of 160 eVee. This science goal will correspond to the most sensitive results for WIMPs with a mass of 2.2--8 GeV/c$^{2}$.

Groundwater is one of the most important natural resources in to sustain the human habitat on earth. It serves us as the major source of drinking water as well as the fresh water resource to be utilized in agriculture and industries. Over the decades the groundwater pumping has been increased few fold and that is raising serious concern about the depth of groundwater level at different parts of earth. The south western Punjab is facing the problem of fluctuating groundwater table due to the heavy agricultural practices in this state. Our study focuses on the observation of change and prediction of groundwater table the in the Muktsar district of south west Punjab, based on the village wise collected well data. Curve fitting technique though MATLAB software has been taken into account for this purpose and it showed a increase in depth to groundwater table for all the four blocks of Muktsar district by 2025. The study highlights the need of raising awareness and establish new laws to ensure sustainable groundwater management in the study area to avoid the scarcity of groundwater in the near future.

In this paper, we focused on the different detector technologies used in the search of [Formula: see text] decay, from beginning till date. We have also explained the advance technology which is planned for near future by various worldwide experimental collaboration in the search of [Formula: see text] decay.

Neutrino is one of the most elusive particles present in the universe. It also possess many puzzling nature. Many of its properties are still a mystery like the mass ordering, nature of neutrino, i.e., whether it is Dirac or Majorana type, and many other things. From oscillation experiments, we can have the idea of mass squared difference, but exact mass of flavor of neutrino is remains a mystery. Till date, we did not have the evidence for Neutrino less double beta decay, this phenomena have the potential to give the idea about the effective Majorana mass. Also neutrino nucleus coherent scattering can tell us about some interesting features about the neutrinos. In this paper, we will discuss different aspects of neutrino physics and the reach of some recent experiments. Also we will discuss some of the future planned experiments in the neutrino sector and the limit up to which they can reach.

Germanium detector is one of the principal detection technologies in the study of dark matter physics, neutrino physics, etc. Among different configurations of germanium detector, point contact configuration is an apt in the study of the low-energy neutrino and low-mass WIMPs. There are two types of point contact configuration, i.e., n-type point contact detectors and p-type point contact detectors, in which p-type point contact germanium detectors possess an inactive layer of few mm thickness and give rise to anomalous surface events. These events are not able to give the correct information about the interaction due to partial charge collection. In order to interpret the accurate result, we have to remove these anomalous surface events from the bulk events, whereas n-type point contacts germanium detectors are free from these anomalous events. Here, we present two different methods to discriminate these events that arise from the surface layer of the p-type point contact germanium detectors.

Study of the nucleus–nucleus interactivity at relativistic energy is one of the prime interests since the past in nuclear physics. It provides the information of reaction mechanism of heavy-ion interactivity with fundamental physics. In the present article, we have focused on the fragmentation characteristics of the projectile fragments (PF) with various target groups of the NED for the events emerged in the interactivity of 84Kr36 + Em at 1 GeV per nucleon. The result of the present analysis is found to be consistence with other experimental results which was performed at relativistic energy.

To look at different modern sectors of physics like the study of dark matter interaction, different properties of neutrino and other exotic particle interaction, detectors having a very low threshold of the order of eVee (electron equivalent) are one of the prime needs. Germanium ionization detector is one of the apt technologies with good resolution and low threshold. Various configurations of a highly pure germanium detector have been used by various collaboration to look at the above-mentioned properties. Among them, the point contact and ultra-low energy detector configurations have shown a very promising energy threshold near the desired range. Ultra-low energy detectors also have a very good resolution, but their low mass is a point of concern in scaling up the detector. Whereas coaxial configuration has a large mass, but the resolution is not that much good. All the advantages and the disadvantages of the highly pure germanium detector technology based on different configurations will be discussed here.

We investigate exotic neutrino interactions using the 205.4 kg$\cdot$day dataset from the CDEX-10 experiment at the China Jinping Underground Laboratory. New constraints on the mass and couplings of new gauge bosons are presented. Two nonstandard neutrino interactions are considered: a $U(1)_{B-L}$ gauge-boson-induced interaction between an active neutrino and electron/nucleus, and a dark-photon-induced interaction between a sterile neutrino and electron/nucleus via kinetic mixing with a photon. This work probes an unexplored parameter space involving sterile neutrino coupling with a dark photon. New laboratory limits are derived on dark photon masses below $1~{\rm eV}/c^{2}$ at some benchmark values of $Δm_{41}^{2}$ and $g^{\prime2}{\rm{sin}}^{2}2θ_{14}$.

A large number of models for physics beyond the standard model predict long-lived particles that may be produced at the CERN LHC and decay into final states containing jets with missing transverse momentum, $$p_{T}^{miss}$$ .

With the advent of Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) technology, Multi-Terminal DC (MTDC) grids are gaining popularity and becoming reality. Half-bridge based Modular Multilevel Converter (H-MMC) along with Hybrid HVDC Breaker (HHB) turns out to be a good combination for MTDC grids, which ensures minimum disturbance to the operation of ac-dc power system during dc faults, enhancing reliability and grid security. In MTDC grid, a dc switchyard is essential at each converter station, which acts as a transition point for various incoming and outgoing feeders. HHB can be designed as an internal equipment of such dc switchyard. The design of such dc switchyard is very important from the operational and cost perspective in achieving the required power system reliability and security. This paper utilizes the modular feature of Hybrid HVDC breaker (HHB) to design a N-feeder dc switchyard with reduced component count. A generalized procedure to develop an electrical layout of N-feeder dc switchyard and its operation are proposed. Operation of a dc switchyard under failure of HHB components is also demonstrated.

The dominant decay mode of a top quark is $$t\rightarrow bW$$ . Hadronic decay of the top quark represents the decay of the W boson into two quarks.

Abstract In this article, we review the possible candidates of dark matter and their proposed properties. We have focused on different methods used for the detection of the dark matter candidates such as, search of WIMPs at the accelerators, indirect and direct detection of WIMPs. We have highlighted the different detector technologies such as, charge collection after ionization, bubble formation in superheated liquid by charge particle, scintillation produced due to the incident radiation, cryogenic detection technique, noble liquid as detector material, time projection chamber, which are used by different experimental collaborations worldwide.