arXiv subjects

M. Bartosik

Publications and source records attributed to M. Bartosik.

5 recordsLinked to original sources

arXiv2019

Recent Results from Polycrystalline CVD Diamond Detectors

Diamond is a material in use at many nuclear and high energy facilities due to its inherent radiation tolerance and ease of use. We have characterized detectors based on chemical vapor deposition (CVD) diamond before and after proton irradiation. We present preliminary results of the spatial resolution of unirradiated and irradiated CVD diamond strip sensors. In addition, we measured the pulse height versus particle rate of unirradiated and irradiated polycrystalline CVD (pCVD) diamond pad detectors up to a particle flux of $20\,\mathrm{MHz/cm^2}$ and a fluence up to $4 \times 10^{15}\,n/\mathrm{cm^2}$.

physics.ins-det↗

arXiv2014

Complementary ab initio and X-ray nano-diffraction study of Ta2O5

Numerous different crystal structures of Ta2O5 are reported in literature. Although experimentally and computationally obtained lattice parameters and mechanical properties are in excellent agreement there is a pronounced deviation when it comes to electronic structures of Ta2O5. Based on ab initio studies and nano-beam X-ray diffraction of sputtered Ta2O5 thin films, we introduce an orthorhombic basic structure with a = 0.6425, b = 0.3769, and c = 0.7706 nm, which is stabilized by flipping of an oxygen atom in neighboring c-planes. The calculated energy of formation is with -3.209 eV/atom almost as low as -3.259 eV/atom for the well-known Stephenson superstructure. We propose the new structure based on the fact that it allows for a good description of orthorhombic Ta2O5 even with a small and simple unit cell, which is especially advantageous for computational studies.

cond-mat.mtrl-sci↗

arXiv2005

TeV Gamma-rays from the Northern Sky Pulsar Wind Nebulae

We estimate the TeV gamma-ray fluxes expected from the population of young pulsars in terms of the self-consistent time dependent hadronic-leptonic model for the high energy processes inside the pulsar wind nebulae. This radiation model bases on the hypothesis of Arons and collaborators who postulate that leptons are accelerated inside the nebulae as a result of resonant scattering on heavy nuclei, which in turn are accelerated in the pulsar wind region or the pulsar inner magnetosphere. Our aim is to find out which nebulae on the nortehrn hemisphere are the best candidates for detection at energies above 60 GeV and 200 GeV by the next generation of low threshold Cherenkov telescopes.

astro-ph↗

arXiv2004

Cosmic rays from Galactic pulsars

We calculate energy spectra and mass composition of cosmic rays accelerated by the galactic population of pulsars during their radio and gamma-ray phase. Several models proposed for the distribution of the initial parameters of the galactic pulsar population are considered. The best description of the observed cosmic ray spectrum and mass composition between 10^15 eV and 10^18 eV is obtained for the model B of Lorimer et al. (1993) in which the logs of initial pulsar periods and surface magnetic fields are given by the Gaussian distributions with the average values of log P[ms] = 2.6 and log B[G] = 12.3, respectively.

astro-ph↗

arXiv2003

Gamma-rays from the pulsar wind nebulae

We investigate the radiation processes inside supernova remnants which are powered by young pulsars. Using recent model for particle acceleration by the pulsar wind nebulae, we obtain the equilibrium spectra of leptons and nuclei inside the nebula as a function of time. We calculate the multiwavelength photon spectra produced by leptons and nuclei and compare them with the observations of the PWNe, i.e. the Crab Nebula, the Vela Supernova Remnant, and the nebula around PSR 1706-44. It is found that the emission from the Crab Nebula can be well fitted by the composition of the gamma-ray emission produced by leptons and nuclei. The model is further tested by successful fitting of the high energy spectrum from the Vela SNR. However, considered model does not give good fitting to the emission from PSR1706-44, for the likely parameters of this source, unless additional target for relativistic leptons is present inside the nebula, e.g. the thermal infrared emission. Based on the knowledge obtained from these fittings, we predict the gamma-ray fluxes in the TeV energy range from other PWNe, i.e. MSH15-52 (PSR 1509-58), 3C58 (PSR J0205+6449), and CTB80 (PSR 1951+32).

astro-ph↗