arXiv subjects

A. Moharana

Publications and source records attributed to A. Moharana.

18 recordsLinked to original sources

arXiv2026

Measurement of the muon flux at SNOLAB using the DEAP-3600 experiment

A direct measurement of the muon flux at SNOLAB is performed using the DEAP-3600 experiment, located 2 km underground at SNOLAB near Sudbury, Canada. Primarily designed for the direct detection of weakly interacting massive particles (WIMPs), a dark matter candidate, DEAP-3600 consists of an inner spherical acrylic vessel containing a liquid argon target; this vessel is enclosed within a steel shell which is submerged in an instrumented water tank, serving as a muon veto for the dark matter search. The muon flux measurement is performed using a cut-and-count analysis of events observed in the muon veto detector and of events which are coincident between the muon veto and the liquid argon target. The requirement that muons traverse both the water and liquid argon minimizes instrumental backgrounds and systematic uncertainties. Using data collected from November 2016 to March 2020, the muon flux is measured by this coincidence analysis to be $(3.71 \pm 0.25_{\textrm{stat}} \pm 0.09_{\textrm{sys}}) \times 10^{-10}\, μ/$cm$^2$/s. The standalone measurement using muon veto data only is compatible within uncertainties. Both measurements agree with the previous result by the SNO experiment and with simulations carried out using the MUTE software. These results provide an important benchmark for future rare-event searches at the SNOLAB facility.

hep-ex↗

arXiv2026

First evidence of neutrino absorption on argon using $^{8}$B solar neutrinos in DEAP-3600

We report experimental evidence for electron neutrino charged-current interactions (neutrino absorption, CC $ν_e$) from $^{8}$B solar neutrinos on $^{40}$Ar using an exposure of ($7.29 \pm 0.05$) tonne$\cdot$years in the DEAP-3600 detector. A region of interest (ROI) of 10.5-13.0 MeV reconstructed energy calibrated on single-peak events, corresponding to incident neutrino energy in 12.0-14.5 MeV, is used for this measurement. We observe 5 single-peak and 1 double-peak neutrino-like events consistent with the $^{8}$B solar neutrino energy spectrum in the ROI after correcting for nonlinearities in the detector response at high energies. With an expected background of $0.48~^{+0.16}_{-0.15}$ events, the data correspond to a significance of $4.0\,σ$ with respect to the background-only hypothesis. We report an energy-averaged cross section of $(4.0~^{+2.0}_{-1.6}~\mathrm{(stat)}~^{+0.8}_{-0.7}~\mathrm{(sys)})\times 10^{-41}\,\mathrm{cm}^2$ in the ROI for the CC $ν_{e}$ signal, a factor $(2.4~^{+1.3}_{-1.0})$ higher than predicted by Bhattacharya, Goodman and García (2009).

hep-ex↗

arXiv2026

RX Gru: a short-period pre-main-sequence eclipsing binary with a distant circumbinary companion

We report the discovery of a new short-period pre-main-sequence eclipsing binary, RX Gru, orbited by a distant circumbinary companion. We characterized the system by analysing the photometric observations from the Solaris network, the Transiting Exoplanet Survey Satellite, and the Super Wide Angle Search for Planets survey, combined with the radial velocities from four high-resolution spectrographs: HARPS, FEROS, CHIRON, and HRS. We derived the parameters of the eclipsing components, which are $M_{\rm Aa} = 1.004^{+0.027}_{-0.026}\,$M$_\odot$, $R_{\rm Aa} = 1.007\pm0.021\,$R$_\odot$, and $T_{\rm eff,Aa} = 5379\pm289\,$K for the primary, and $M_{\rm Ab} = 0.985^{+0.024}_{-0.025}\,$M$_\odot$, $R_{\rm Ab} = 1.024\pm0.023\,$R$_\odot$, and $T_{\rm eff,Ab} = 5322\pm278\,$K for the secondary. We determined the age of the system from the observed parameters using two evolution codes, MESA and Cesam2k20. We obtained an age of $\sim$28$\,$Myr, placing the two stars at the very end of the pre-main-sequence phase. We also derived the minimum mass and orbital period of the tertiary companion, which are found to be $M_{\rm B} = 89.0\pm3.5\,$M$_{\rm Jup}$ and $P_{\rm AB} = 23.79 ^{+0.10 }_{-0.25}\,$yr, respectively. We conclude that RX Gru consists of a tight inner binary composed of two twin components and an outer low-mass companion (a massive brown dwarf or a very low-mass star) in a relatively wide orbit, and we suggest that the system was formed via the dynamical unfolding mechanism coupled with the shared accretion of the circumbinary material by the binary components.

astro-ph.SR↗

arXiv2026

V446 Cephei: a $β$ Cep pulsator in a multiple system

$β$ Cep stars in eclipsing binary (EB) systems give us an opportunity to put observational constraints on their structure and stellar parameters. We present a comprehensive analysis of the $β$ Cep star in the EB V446 Cep, using \textit{TESS} photometry and HERMES spectra. We calculate the stellar and orbital parameters using light curve modelling and spectral disentangling. The EB has an orbital period of $3.808567 \pm 0.000012$ d and a mass ratio of $0.1550 \pm 0.0012$. We find the $β$ Cep star to have a mass of $10.68 \pm 0.06$ $\mathrm{M_{\odot}}$, a radius of $5.864 \pm 0.033$ $\mathrm{R}_{\odot}$, and a $T_{\rm eff}$ of $24220 \pm 180$ K. The secondary has a mass of $1.657 \pm 0.017$ $\mathrm{M_{\odot}}$, a radius of $1.530 \pm 0.014$ $\mathrm{R}_{\odot}$, and a $T_{\rm eff}$ of $9080 \pm 390$ K. We also extract the abundances of C, N, O, Mg, and Si for the $β$ Cep star, which are found to be consistent with galactic OB binaries. We identified 21 distinct pulsation frequencies, with the dominant mode at 10.24324 d$^{-1}$, which corresponds to a near-harmonic of the system's orbital frequency. The two stars in the EB have asynchronous rotation, with both stars rotating faster than the orbital frequency. We detect a companion to the EB using eclipse timing variations and period changes of the dominant pulsation frequency. We calculate the minimum mass of this tertiary companion to be $4.11 \pm 0.32$ $\mathrm{M_{\odot}}$ which is on an orbit of 2303$\pm$69 d around the EB. Using spectral energy distributions and MIST isochrones, we conclude that V446 Cep is either a co-evolving hierarchical 2+2 quadruple or a triple system where the third body is a compact object.

astro-ph.SR↗

arXiv2026

Dark Matter Search with the DEAP-3600 Detector using the Profile Likelihood Ratio Method

We present here a search for WIMP dark matter using 790.8 live-days of data collected with 3269 kg of liquid argon (1266 kg fiducial) by the DEAP-3600 detector at SNOLAB, using the Profile Likelihood Ratio method. The likelihood model is based on three parameters: estimated energy, pulse-shape discrimination parameter, and reconstructed position within the detector. Using this method, the expected signal sensitivity of DEAP-3600 benefits from an increased fiducial volume and improved event selection acceptance. Alpha-decays from a small number of dust particulates circulating within the liquid argon target are the dominant source of background events and limit the sensitivity of this search. This result provides improved exclusion upper limits on the WIMP-nucleon spin-independent cross section on liquid argon for WIMP masses between 20 GeV/$c^{2}$ and 100 GeV/$c^{2}$. At 100 GeV/$c^{2}$ the observed limit is 3.4 $\times$ 10$^{-45}$ cm$^2$ at 90% confidence level.

hep-ex↗

arXiv2026

Time-Domain Photometry and Activity Evolution of Interstellar Comet 3I/ATLAS with BHTOM

Time-domain photometric monitoring is essential for characterizing cometary evolution, particularly for rare interstellar objects with limited observing opportunities. We aimed to characterize the pre-perihelion photometric behavior and dust activity of the interstellar comet 3I/ATLAS, and to test the capability of the Black Hole Target and Observation Manager (BHTOM) platform and telescope network for coordinated high-cadence non-sidereal observations. We obtained 70 days of time-series photometry of 3I/ATLAS from 2025 July 4 - September 11 using 16 telescopes and 1554 images. The data were processed and calibrated with the BHTOM pipeline. High-cadence, multi-band imaging was used to measure the rotation period and color evolution, while the dust activity was quantified via Afp measurements. We present a pre-perihelion light curve of 3I/ATLAS from Rh = 3.18 - 2.19 au, which exhibited a steady increase of ~3 magnitudes with no evidence of anomalous behavior. We measured a rotation period of P_rot = 15.98 +/- 0.08 h. The relative dust production increased from A(0)fp ~600 - 1100 cm, and the upper limit on the dust mass-loss rate increased from \leq 217 kg/s to \leq 328 kg/s. We measured an activity index of n = -1.24 +/- 0.02, consistent with a well-developed dust coma. The colors were statistically non-changing, with only a weak, non-significant tendency for 3I/ATLAS to become bluer at 3.5 > Rh > 2.2 au.

astro-ph.EP↗

arXiv2025

Relative Measurement and Extrapolation of the Scintillation Quenching Factor of $α$-Particles in Liquid Argon using DEAP-3600 Data

The knowledge of scintillation quenching of $α$-particles plays a paramount role in understanding $α$-induced backgrounds and improving the sensitivity of liquid argon-based direct detection of dark matter experiments. We performed a relative measurement of scintillation quenching in the MeV energy region using radioactive isotopes ($^{222}$Rn, $^{218}$Po and $^{214}$Po isotopes) present in trace amounts in the DEAP-3600 detector and quantified the uncertainty of extrapolating the quenching factor to the low-energy region.

physics.ins-det↗

arXiv2025

Direct Measurement of the $^{39}$Ar Half-life from 3.4 Years of Data with the DEAP-3600 Detector

The half-life of $^{39}$Ar is measured using the DEAP-3600 detector located 2 km underground at SNOLAB. Between 2016 and 2020, DEAP-3600 used a target mass of (3269 $\pm$ 24) kg of liquid argon distilled from the atmosphere in a direct-detection dark matter search. Such an argon mass also enables direct measurements of argon isotope properties. The decay of $^{39}$Ar in DEAP-3600 is the dominant source of triggers by two orders of magnitude, ensuring high statistics and making DEAP-3600 well-suited for measuring this isotope's half-life. Use of the pulse-shape discrimination technique in DEAP-3600 allows powerful discrimination between nuclear recoils and electron recoils, resulting in the selection of a clean sample of $^{39}$Ar decays. Observing over a period of 3.4 years, the $^{39}$Ar half-life is measured to be $(302 \pm 8_{\rm stat} \pm 6_{\rm sys})$ years. This new direct measurement suggests that the half-life of $^{39}$Ar is significantly longer than the accepted value, with potential implications for measurements using this isotope's half-life as input.

nucl-ex↗

arXiv2025

Meat, Vegetable, Soup -- The First Successful Attempt to Classify Everything

We present the results of a novel classification scheme for all items, objects, concepts, and crucially -- things -- in the known and unknown universe. Our definitions of meat, soup and vegetable are near-exhaustive and represent a new era of scientific discovery within the rapidly-developing field of Arbitrary Classification. While the definitions of vegetable (growing in the ground), meat (growing in an animal) and soup (containing both vegetable and meat) may appear simple at first, we discuss a range of complex cases in which progress is rapidly being made, and provide definitions and clarifications for as many objects as a weekend of typing will allow.

physics.pop-ph↗

arXiv2025

A comprehensive study of $δ$ Scuti-type pulsators in eclipsing binaries: oscillating eclipsing Algols

Eclipsing double-lined spectroscopic binaries hosting $δ$ Scuti-type pulsators offer a unique laboratory for simultaneously constraining stellar geometry and interior structure. In this study, we present a comprehensive analysis of five oscillating eclipsing Algol binaries. By combining high-precision, short-cadence TESS photometry with multi-epoch high-resolution spectroscopy, we derive precise stellar and orbital parameters. Frequency power spectra were obtained using residuals from binary modelling. We further investigate the evolutionary history of these systems using a grid of MESA binary evolution simulations. Our analysis suggests that the systems must have undergone either case A or case B mass transfer, with the primary components repositioned in the Hertzsprung-Russell diagram and now pulsating in the $δ$ Scuti regime, while the cooler secondaries are underluminous and inflated, filling their Roche lobes. This study contributes to the growing catalog of well-characterised oEA systems and our understanding of the effects of mass-transfer on the fate of these short-period binaries.

astro-ph.SR↗

arXiv2024

Comprehensive study of five candidate delta Scuti-type pulsators in detached eclipsing binaries

Pulsating stars in eclipsing binaries (EBs) provide an excellent opportunity to obtain precise, model-independent stellar parameters for studying oscillations in detail. One common class of pulsators in these EBs exhibits delta Scuti-type oscillations. Characterising these pulsators using the precise parameters obtained from EB modelling enhances our understanding of such stars and strengthens asteroseismic studies. We conducted a comprehensive photometric and spectroscopic analysis of candidate pulsators in detached EBs to expand the sample of systems with accurately determined absolute parameters. We performed radial velocity and light curve modelling to estimate the absolute stellar parameters, along with detailed spectroscopic modelling to obtain global metallicity and temperatures. Frequency power spectra were derived from the residuals of binary modelling. Isochrones were used to determine the stars' ages, which were then compared to theoretically obtained values. We present a detailed analysis of four candidate delta Scuti-type pulsators in EBs and update the light curve analysis of the previously studied system TIC 308953703. The masses and radii of the components are constrained with high accuracy, aiding in age estimation. We perform a Fourier analysis of the observed oscillations and explore their origin. For TIC 81702112, we report tidal effects causing amplitude variation in the oscillation frequencies over the orbital phase.

astro-ph.SR↗

arXiv2024

Discovery of a hot post-AGB star in Galactic globular cluster E3

We report a new hot post-asymptotic giant branch (PAGB) star in the Galactic globular cluster (GC) E3, which is one of the first of the identified PAGB stars in a GC to show a binary signature. The star stands out as the brightest source in E3 in the \mbox{\em Astrosat}/UVIT images. We confirmed its membership with the cluster E3 using Gaia DR3 kinematics and parallax measurements. We supplemented the photometric observations with radial velocities (RVs) from high-resolution spectroscopic observations at two epochs and with ground- and space-based photometric observations from 0.13 $μ$m to 22 $μ$m. We find that the RVs vary over $\sim$6 \kms\ between the two epochs. This is an indication of the star being in a binary orbit. A simulation of possible binary systems with the observed RVs suggests a binary period of either 39.12 days or 17.83 days with mass ratio q$\geq$1.0. The [Fe/H] derived using the high-resolution spectra is $\sim -$0.7 dex, which closely matches the cluster metallicity. The spectroscopic and photometric measurements suggest \Teff\ and $\log g$ of the star as 17\,500$\pm$1\,000~K and 2.37$\pm$0.20~dex, respectively. Various PAGB evolutionary tracks on the Hertzsprung--Russell (H-R) diagram suggest a current mass of the star in the range 0.51$-$0.55 \Msun. The star is enriched with C and O abundances, showing similar CNO abundances compared to the other PAGB stars in GCs with the evidence of the third dredge-up on the AGB phase.

astro-ph.SR↗

arXiv2023

Comprehensive spectroscopic and photometric study of pulsating eclipsing binary star AI Hya

The pulsating eclipsing binaries are remarkable systems that provide an opportunity to probe the stellar interior and to determine the fundamental stellar parameters precisely. Especially the detached eclipsing binary systems with (a) pulsating component(s) are significant objects to understand the nature of the oscillations since the binary effects in these systems are negligible. Recent studies based on space data have shown that the pulsation mechanisms of some oscillating stars are not completely understood. Hence, comprehensive studies of a number of pulsating stars within detached eclipsing binaries are important. In this study, we present a detailed analysis of the pulsating detached eclipsing binary system AI Hya which was studied by two independent groups with different methods. We carried out a spectroscopic survey to estimate the orbital parameters via radial velocity measurements and the atmospheric parameters of each binary component using the composite and/or disentangled spectra. We found that the more luminous component of the system is a massive, cool and chemically normal star while the hotter binary component is a slightly metal-rich object. The fundamental parameters of AI Hya were determined by the analysis of binary variations and subsequently used in the evolutionary modelling. Consequently, we obtained the age of the system as 850 $\pm$ 20 Myr and found that both binary components are situated in the Delta Scuti instability strip. The frequency analysis revealed pulsation frequencies between the 5.5 - 13.0 d$^{-1}$ and we tried to estimate which binary component is the pulsating one. However, it turned out that those frequencies could originate from both binary components.

astro-ph.SR↗

arXiv2022

SiPM cross-talk in liquid argon detectors

SiPM-based readouts are becoming the standard for light detection in particle detectors given their superior resolution and ease of use with respect to vacuum tube photo-multipliers. However, the contributions of detection noise such as the dark rate, cross-talk, and after-pulsing may impact significantly their performance. In this work, we present the development of highly reflective single-phase argon chambers capable of light yields up to 32 photo-electrons per keV, with roughly 12 being primary photo-electrons generated by the argon scintillation, while the rest are accounted by optical cross-talk. Furthermore, the presence of compound processes results in a generalized Fano factor larger than 2 already at an over-voltage of 5 V. Finally, we present a parametrization of the optical cross-talk for the FBK NUV-HD-Cryo SiPMs at 87 K that can be extended to future detectors with tailored optical simulations.

physics.ins-det↗

arXiv2022

Direct comparison of PEN and TPB wavelength shifters in a liquid argon detector

A large number of particle detectors employ liquid argon as their target material owing to its high scintillation yield and its ability to drift ionization charge over large distances. Scintillation light from argon is peaked at 128 nm and a wavelength shifter is required for its efficient detection. In this work, we directly compare the light yield achieved in two identical liquid argon chambers, one of which is equipped with PolyEthylene Naphthalate (PEN) and the other with TetraPhenyl Butadiene (TPB) wavelength shifter. Both chambers are lined with enhanced specular reflectors and instrumented with SiPMs with a coverage fraction of approximately 1%, which represents a geometry comparable to the future large scale detectors. We measured the light yield of the PEN chamber to be 39.4$\pm$0.4(stat)$\pm$1.9(syst)% of the yield of the TPB chamber. Using a Monte Carlo simulation this result is used to extract the wavelength shifting efficiency of PEN relative to TPB equal to 47.2$\pm$5.7%. This result paves the way for the use of easily available PEN foils as a wavelength shifter, which can substantially simplify the construction of future liquid argon detectors.

physics.ins-det↗

arXiv2022

Very large SiPM arrays with aggregated output

In this work we will document the design and the performances of a SiPM-based photodetector with a surface area of 100 cm$^2$ conceived to operate as a replacement for PMTs. The signals from 94 SiPMs are summed up to produce an aggregated output that exhibits in liquid nitrogen a dark count rate (DCR) lower than 100 cps over the entire surface, a signal to noise ratio better than 13, and a timing resolution better than 5.5 ns. The module feeds about 360 mW at 5 V with a dynamic range in excess of 500 photo-electrons on a 100 $Ω$ differential line. The unit is compatible with operations at room temperature, with a DCR increased by about 6 orders of magnitude.

physics.ins-det↗

arXiv2021

Orbital and physical parameters of eclipsing binaries from the ASAS catalogue -- XII. A sample of systems with $K2$ photometry

We present results of the analysis of light and radial velocity (RV) curves of eight detached eclipsing binaries observed by the All-Sky Automated Survey, which we have followed up with high-resolution spectroscopy, and were later observed by the $Kepler$ satellite as part of the $K2$ mission. The RV measurements came from spectra obtained with OAO-188/HIDES, MPG-2.2m/FEROS, SMARTS 1.5m/CHIRON, Euler/CORALIE, ESO-3.6m/HARPS, and OHP-1.93/ELODIE instruments. The $K2$ time-series photometry was analyzed with the JKTEBOP code, with out-of-eclipse modulations of different origin taken into account. Individual component spectra were retrieved with the FD3 code, and analyzed with the code iSpec in order to determine effective temperatures and metallicities. Absolute values of masses, radii, and other stellar parameters are calculated, as well as ages, found through isochrone fitting. For five systems such analysis has been done for the first time. The presented sample consists of a variety of stars, from low-mass dwarfs, through G and F-type Main Sequence objects, to evolved active sub-giants, one of which is found to be crossing the Hertzsprung gap. One target may contain a $γ$ Dor-type pulsator, two more are parts of higher-order multiples, and spectra of their tertiaries were also retrieved and used to constrain the properties of these systems.

astro-ph.SR↗

arXiv2020

Consequences of parameterization choice on eclipsing binary light curve solutions

Eclipsing Binaries (EBs) are known to be the source of most accurate stellar parameters, which are important for testing theories of stellar evolution. With improved quality and quantity of observations using space telescopes like {\it TESS}, there is an urgent need for accuracy in modeling to obtain precise parameters. We use the soon to be released \texttt{PHOEBE 2.3} EB modeling package to test the robustness and accuracy of parameters and their dependency on choice of parameters for optimization.

astro-ph.SR↗