A5067921991- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Scientific Research and Discoveries
- Radiation Therapy and Dosimetry
- Black Holes and Theoretical Physics
- Radio Astronomy Observations and Technology
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Radiation Detection and Scintillator Technologies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Statistical Mechanics and Entropy
- Earth Systems and Cosmic Evolution
- Advanced Thermodynamics and Statistical Mechanics
- Nuclear Physics and Applications
- Computational Physics and Python Applications
Laboratoire d’Annecy de Physique des Particules
2024
Saha Institute of Nuclear Physics
2012-2022
GGG (France)
2021
Washington University in St. Louis
2013-2014
Indian Institute of Astrophysics
1998-2007
Goddard Space Flight Center
1997-2000
University of Chicago
1989-1996
Fermi National Accelerator Laboratory
1989-1996
Isaac Newton Institute for Mathematical Sciences
1995
University of Cambridge
1995
New results are reported from the operation of PICO-60 dark matter detector, a bubble chamber filled with 52 kg C_{3}F_{8} located in SNOLAB underground laboratory. As previous PICO chambers, exhibits excellent electron recoil and alpha decay rejection, observed multiple-scattering neutron rate indicates single-scatter background less than one event per month. A blind analysis an efficiency-corrected 1167-kg day exposure at 3.3-keV thermodynamic threshold reveals no single-scattering nuclear...
New data are reported from the operation of a 2 liter ${\mathrm{C}}_{3}{\mathrm{F}}_{8}$ bubble chamber in SNOLAB underground laboratory, with total exposure 211.5 kg days at four different energy thresholds below 10 keV. These show that provides excellent electron-recoil and alpha rejection capabilities very low thresholds. The exhibits an sensitivity $<3.5\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}10}$ factor $>98.2%$. also include first observation dependence acoustic signal on...
Recent results from the PICASSO dark matter search experiment at SNOLAB are reported. These were obtained using a subset of 10 detectors with total target mass 0.72 kg 19F and an exposure 114 kgd. The low backgrounds in allow recoil energy thresholds as 1.7 keV to be which increased sensitivity interactions Weakly Interacting Massive Particles (WIMPs) masses below GeV/c^2. No signal was found. Best exclusion limits spin dependent sector for WIMP 20 GeV/c^2 cross section on protons sigma_p^SD...
The nature of dark matter and properties neutrinos are among the most pressing issues in contemporary particle physics. dual-phase xenon time-projection chamber is leading technology to cover available parameter space for Weakly Interacting Massive Particles (WIMPs), while featuring extensive sensitivity many alternative candidates. These detectors can also study through neutrinoless double-beta decay a variety astrophysical sources. A next-generation xenon-based detector will therefore be...
The ultrahigh-energy (UHE) proton and neutrino spectra resulting from collapse or annihilation of topological defects surviving the grand unification (GUT) era are calculated. Irrespective specific process under consideration, UHE spectrum ``recovers'' at \ensuremath{\sim}1.8\ifmmode\times\else\texttimes\fi{}${10}^{11}$ GeV after a partial Greisen-Zatsepin-Kuz'min ``cutoff'' \ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}${10}^{10}$ continues to GUT-scale energy with universal shape...
The rotation curve (RC) of our Galaxy, the Milky Way, is constructed starting from its very inner regions (few hundred pc) out to a large Galactocentric distance $\sim 200$ kpc using kinematical data on variety tracer objects moving in gravitational potential without assuming any theoretical models visible and dark matter components Galaxy. We study effect RC due uncertainties values Galactic Constants (GCs) $R_\odot$ $V_\odot$ (these being sun's circular speed around center, respectively)...
The PICO collaboration reports results obtained by PICO-2L Run-2 after carefully controlling for particulate contamination. data clearly indicates that previously observed anomalies were due to contamination in the bubble chamber fluid. These observations set new bounds on spin-dependent scattering of dark matter, and help pave way larger scale experiments.
New data are reported from the operation of PICO-60 dark matter detector, a bubble chamber filled with 36.8 kg CF$_3$I and located in SNOLAB underground laboratory. is largest to search for date. With an analyzed exposure 92.8 livedays, exhibits same excellent background rejection observed smaller chambers. Alpha decays exhibit frequency-dependent acoustic calorimetry, similar but not identical that recently C$_3$F$_8$ chamber. also observes large population unknown events, exhibiting...
Recently there has been a hint of gamma-ray line at 130 GeV originated from the galactic centre after analysis Fermi-LAT satellite data. Being monochromatic in nature, it rules out possibility having its astrophysical origin and speculation that this could be dark matter annihilation. In work, we propose two component scenario where an extension Standard Model by inert Higgs doublet gauge singlet scalar concocted with Z2 × Z'2 symmetry, is considered. We find our can not only explain through...
Context:The HAGAR Telescope Array at Hanle, Ladakh has been regularly monitoring the nearby blazar Mkn 421 for past 7yrs. Aims: Blazars show flux variability in all timescales across electromagnetic spectrum. While there is abundant literature characterizing short term flares from different blazars, comparatively little work done to study long variability. We aim temporal and spectral radiation during 2009-2015. Methods: quantify lognormality radio VHE bands, compute correlations between...
We explore scenarios where the highest energy cosmic rays are produced by new particle physics near grand unification scale. Using detailed numerical simulations of extragalactic nucleon, \ensuremath{\gamma}-ray, and neutrino propagation, we show existence an interesting parameter range for which such may explain part data consistent with all observational constraints. A combination proposed observatories ultra-high rays, telescopes $\ensuremath{\gtrsim}\mathrm{few}$ kilometer scale,...
The evolution of a network strings produced at grand-unification phase transition in an expanding universe is discussed, with particular reference to the processes energy exchange between and rest universe. This supported by numerical calculations simulating behavior It found that order density does not come dominate total there must be efficient mechanism for loss---the only plausible one being production closed loops their subsequent decay via gravitational radiation.
We calculate the flux of ultrahigh-energy protons due to process ``cusp evaporation'' from cosmic-string loops. For ``standard'' value dimensionless parameter \ensuremath{\epsilon}==G\ensuremath{\mu}\ensuremath{\approxeq}${10}^{\mathrm{\ensuremath{-}}6}$, is several orders magnitude below observed cosmic-ray protons. However, at any energy initially increases as \ensuremath{\epsilon} decreased. This first suggests that there may be a lower limit on \ensuremath{\epsilon}, which would imply...
The velocity distribution function (VDF) of the hypothetical Weakly Interacting Massive Particles (WIMPs), currently most favored candidate for Dark Matter (DM) in Galaxy, is determined directly from circular speed ("rotation") curve data Galaxy assuming isotropic VDF. This done by "inverting" --- using Eddington's method Navarro-Frenk-White universal density profile DM halo parameters which are determined, Markov Chain Monte Carlo (MCMC) technique, a recently compiled set observational on...
The possibility of observing supernova (SN) neutrinos through the process coherent elastic neutrino-nucleus scattering (CENNS) in future ton scale detectors designed primarily for direct detection dark matter is investigated. In particular, we focus on distinguishing various phases SN neutrino emission. emission rates from recent long-term Basel/Darmstadt simulations are used to calculate expected event rates. state-of-the-art predict closer fluxes among different flavors and lower average...
Cosmic rays with energies exceeding ${10}^{20}$ eV have been detected. The origin of these highest energy cosmic remains unknown. Established astrophysical acceleration mechanisms encounter severe difficulties in accelerating particles to energies. Alternative scenarios where are created by the decay topological defects suggested literature. In this paper we study possibility producing through a process that involves formation metastable magnetic monopole-antimonopole bound states and their...
The hypothesis of topological defects (from grand unified and/or Planck scales) as the sources extremely high-energy (> ${10}^{18}$ eV) cosmic rays predicts an unusually high content $\ensuremath{\gamma}$ at energies $E\ensuremath{\gtrsim}{10}^{20}\mathrm{eV} (\frac{\ensuremath{\gamma}}{p}\ensuremath{\ge}1)$ and $E\ensuremath{\lesssim}{10}^{14}\mathrm{eV} (\frac{\ensuremath{\gamma}}{p}\ensuremath{\gtrsim}{10}^{\ensuremath{-}3})$. This can be used a signature for testing in forthcoming experiments.
Abstract Galaxy clusters are expected to be both dark matter (DM) reservoirs and storage rooms for the cosmic-ray protons (CRp) that accumulate along cluster's formation history. Accordingly, they excellent targets search signals of DM annihilation decay at γ -ray energies predicted sources large-scale emission due hadronic interactions in intracluster medium (ICM). In this paper, we estimate sensitivity Cherenkov Telescope Array (CTA) detect diffuse from Perseus galaxy cluster. We first...
The abundance and size distribution of quark nuggets (QN), formed a few microseconds after the big bang due to first order QCD phase transition in early universe, has been estimated. It appears that stable QNs could be viable candidate for cosmological dark matter. evolution baryon inhomogeneity evaporated (unstable) are also examined.
The question of the survivability quark nuggets against process baryon evaporation from their surfaces is studied within context a dynamical model, namely, chromoelectric flux-tube fission model formation and evaporation. Depending on temperature at which nuggests are formed in early Universe value bag constant $B$, our conservative estimates (we overestimate rate) show that with an initial number \ensuremath{\sim}${10}^{44}$ or more can survive be present today.
Direct detection of Weakly Interacting Massive Particle (WIMP) candidates Dark Matter (DM) is studied within the context a self-consistent truncated isothermal model finite-size dark halo Galaxy based on "King model" phase space distribution function collisionless DM particles. Our takes into account modifications phase-space structure due to gravitational influence observed visible matter in manner. The parameters are determined by fit recently circular rotation curve that extends up $\sim$...