D. P. Bhattacharyya

Bio: D. P. Bhattacharyya is an academic researcher from Indian Association for the Cultivation of Science. The author has contributed to research in topics: Muon & Cosmic ray. The author has an hindex of 5, co-authored 40 publications receiving 88 citations.

Absolute low-latitude sea-level muon intensity at large zenith angle

Abstract: The absolute sea-level cosmic-ray muon intensity has been estimated by using a flash-tube range spectrograph at axial zenith angles 75 degree--85 degree W near the geomagnetic equator in the cutoff-momentum region 0.4 GeV/c. The measured absolute muon intensity agrees with the results calculated in the manner of Ashton et al., assuming K/$pi$ = 0 for zenith angles up to 81 degree W and K/ $pi$ = 0.4 for 85 degree W. The angular distribution of muons obeys a cosine- square law. The measured absolute integral muon spectrum at axial zenith angle 81 degree W in the cutoff-momentum interval 0.4--3 GeV/c agrees with the theoretical spectral shape calculated in the manner of Barrett et al. (AIP)

Estimation of chemical abundance of primary cosmic-ray nuclei over Alice Springs using balloon-borne passive detectors

Abstract: A stack consisting of CR-39 (HCB 0.5%), nuclear emulsions and X-ray films was exposed to primary cosmic rays by a balloon lauched from Alice Springs in 1983 and was flown for 32 hours at an atmospheric depth 9.8 g cm−2 air. The recovered plastic plates were etched in 7.5 N NaOH solution at 80°C for 96 hours. The major and minor axes of the elliptic etch pits were analysed. About 1112 elliptic etch pits were scanned. The measured integral flux of very heavy (VH) and Fe nuclei above 3.5 GeV/n are in approximate aggreement with the earlier survey of Dokeet al., but yield a flatter energy spectrum when compared to the recent high-energy extrapolated spectrum of Zatsepinet al. The charges of the detected heavy nuclei were also confirmed from delta-ray counting of heavily ionized tracks in nuclear emulsions. The energy of the incident heavy nuclei has been measured from the distribution of opening angles of alpha fragments initiated by heavy nuclei in nuclear emulsions.

Interactions of 0.45 GeVn 3684Kr ions on CR-39(MA-ND)

Abstract: Hungarian brand CR-39(MA-ND) stack was irradiated at a zenith angle 30° by 36 84 Kr ions of energy 0.45 GeV/ n using Lawrence Berkeley Laboratory BEVALAC beam. The exposed plate was etched in 6N NaOH aqueous solution at 70°C for 20 h. About 636 etch pit diameters were optically measured. The response to Kr ions and the projectile fragment tracks produced in CR-39(MA-ND) target were determined for gb = 0.737. The charge resolution of the CR-39 plastic at the Kr peak was found to be 0.26 e obtained from the average of double cone etch pit data. An increase of the measured partial inelastic cross sections with nuclei charge number in the range 25 ⩽ Z ⩽ 35 has been found. Indication of ΔZ = + 1 events has been observed whose cross section is in accord with the survey presented by Ren Guoxiao et al. The experimental fragmentation cross sections have been compared with the expected results from the semi-empirical nuclear fragmentation model of Wilson et al.

Derivation of muon spectrum at high energies from the recent JACEE primary cosmic-ray spectrum using Fermilab data on meson production

Abstract: The energy spectrum of sea level muons in the range (102÷104) GeV has been calculated from the latest directly measured JACEE primary spectrum using Fermilab results on pp→π± X and pp→K± X inclusive reactions. The conventional pion atmospheric diffusion equation after Bugaevet al. has been used in this analysis to account the flux of muons emerged from the multiple generation of mesons in air. The derived muon spectrum has been compared with the earlier magnetic spectrograph data of Durham and Kiel groups. The latest BAKSAN scintillator telescope data is well in agreement with the calculated integral spectrum originated from the meson decays in the range (1÷104) GeV.

Absolute sea level muon spectrum near equator in the momentum range 0.32-3 GeV/c

Abstract: A study has been made on the differential spectrum of single muons near the geomagnetic equator (12°N) in the momentum range 0.32–3 GeV/c by using the differential range spectrograph results. The corrected experimental spectrum has been compared with those of other workers determined at low high and high latitudes. The present results agree with the theoretical spectra calculated after Barrett et al. and Olbert for the same location within 10% above muon momentum 1 GeV/c. The corrections for the geomagnetic and atmospheric latitude effects have been applied to our low latitude spectrum by using the theory of Olbert and Jabs to explain the deviation of the Kiel muon spectrum of Allkofer and Knoblich from ours.

Atmospheric muon flux at sea level, underground and underwater

Abstract: The vertical sea-level muon spectrum at energies above 1 GeV and the muon intensities at depths up to 18 km w.e. in different rocks and in water are calculated. The results are particularly collated with a great body of the ground-level, underground, and underwater muon data. In the hadron-cascade calculations, we take into account the logarithmic growth with energy of inelastic cross sections and pion, kaon, and nucleon generation in pion-nucleus collisions. For evaluating the prompt-muon contribution to the muon flux, we apply the two phenomenological approaches to the charm production problem: the recombination quark-parton model and the quark-gluon string model. To solve the muon transport equation at large depths of a homogeneous medium, we used a semianalytical method, which allows the inclusion of an arbitrary ~decreasing! muon spectrum at the medium boundary and real energy dependence of both continuous and discrete muon energy losses. The method is checked for accuracy by direct Monte Carlo calculation. Whenever possible, we give simple fitting formulas describing our numerical results. @S0556-2821~98!00313-0# PACS number~s!: 13.85.Tp, 96.40.Tv

Cosmic Strings and Domain Walls

Abstract: Phase transitions in the early universe can give rise to microscopic topological defects: vacuum domain walls, strings, walls bounded by strings, and monopoles connected by strings. This article reviews the formation, physical properties and the cosmological evolution of various defects. A particular attention is paid to strings and their cosmological consequences, including the string scenario of galaxy formation and possible observational effects of strings.

Lepton fluxes from atmospheric charm

Abstract: We reexamine the charm contribution to atmospheric lepton fluxes in the context of perturbative QCD. We include next-to-leading order corrections and discuss theoretical uncertainties due to the extrapolations of the gluon distributions at small {ital x}. We show that the charm contribution to the atmospheric muon flux becomes dominant over the conventional contribution from {pi} and {ital K} decays at energies of about 10{sup 5} GeV. We compare our fluxes with previous calculations. {copyright} {ital 1999} {ital The American Physical Society}

Cosmic Rays: A Review for Astrobiologists

Abstract: Cosmic rays represent one of the most fascinating research themes in modern astronomy and physics. Significant progress is being made toward an understanding of the astrophysics of the sources of cosmic rays and the physics of interactions in the ultrahigh-energy range. This is possible because several new experiments in these areas have been initiated. Cosmic rays may hold answers to a great number of fundamental questions, but they also shape our natural habitat and influence the radiation environment of our planet Earth. The importance of the study of cosmic rays has been acknowledged in many fields, including space weather science and astrobiology. Here, we concentrate on the astrobiological aspects of cosmic rays with regard to the enormous amount of new data available, some of which may, in fact, improve our knowledge about the radiation of cosmic origin on Earth. We focus on fluxes arriving at Earth and doses received, and will guide the reader through the wealth of scientific literature on cosmic rays. We have prepared a concise and self-contained source of data and recipes useful for performing interdisciplinary research in cosmic rays and their effects on life on Earth.