D. P. Bhattacharyya

Derivation of vertical muon spectra at superhigh energies from our predicted primary cosmic-ray spectrum using machine interaction parameters and Feynman scaling hypothesis

SummaryThe vertical differential and integral, muon spectra at super-high energies,viz. up to 10 TeV have been estimated from our predicted primary spectrum of the formN(E)dE=2.4E−2.7dE (cm2s sr GeV)−1. The accelerator data of Johnsonet al., Elbertet al. have been used for the evaluation of fractional hadronic energy moments. By using the conventional Feynman scaling hypothesis and the meson atmospheric diffusion equation after Bugaevet al., the differential and integral muon spectra have been estimated and the results are well in accord with the experimental data of Bakeret al., Allkoferet al., Ayreet al., Aminevaet al., Menon and Ramana Murthy, and Sheldonet al. in the spectral range (0.1÷10) TeV.

Estimation of elemental abundances of heavy cosmic-ray primaries at the top of the atmosphere using plastic emulsion chamber and the derived source spectrum from the steady-state leaky box model

SummaryFinal results of the experiment for the estimation of charge abundances using plastic emulsion chamber consisting of CR-39 (HCB) and Fuji ET-7B nuclear-emulsion sheet, launched from Alice Springs for 32 hours at an atmospheric depth of 9.8 g cm−2 is presented. The latest long hour etching technique was used for track detection in plastics. The estimated reduced etch rate distribution presented was based on 2968 measured track diameter data in CR-39 (HCB) stacks. The observed charge spectrum from the reduced etch rate distribution was duly corrected for the top of the atmosphere by adopting the conventional formulation for cosmic-ray propagation along with the latest modified partial cross-sections for A-A collisions after Tsaoet al. The average value of the observed energy of the 77 very heavy primaries was estimated from the opening angle measurements of alpha fragments in Fuji ET-7B nuclear emulsion and was found to be 5.01 GeV/n which comes out to be 8.2 GeV/n, when corrected for the top of the atmosphere due to propagation in the residual atmospheric depth. The measured integral fluxes for NeMgSi and Fe groups above 4 GeV/n have been compared with the global data surveyed by Ichimuraet al. Our results on element/Si and element/Fe have been compared with the HEAO-3-C2 data after Englemannet al. Using SSLB model, the source abundance is derived from the observed result and that was compared with the results of Juliusson,et al., Lezniak and Webber and Garcia-Munozet al.

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.

Response of CR-39(DOP) as a relativistic 238U-ion detector

Abstract Pershore made CR-39(DOP) solid state nuclear track detector was irradiated at a zenith angle of 30° by 238U-ions of energy 0.927 GeV/n using LBL BEVALAC beam. The exposed plate has been etched in 6.25N NaOH solution at 70°C for one hour. About 1094 cone lengths of the incident U-beam in CR-39(DOP) have been optically measured. The track registration sensitivity ( V T V G ) has been estimated and was found to be (127.7±10.5). The dependence of charge response of CR-39(DOP) detector on restricted energy loss of ultra heavy projectile ions has been studied, to explore the strong departure from Z2-dependence of the response function.

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

SummaryThe 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.

Study of fragmentation in56Fe+27Al interactions at 1.88A GeV using CR-39 (DOP) solid-state nuclear-track detector

Summary1.88A GeV56Fe beam of Lawrence Berkeley Laboratory BEVALAC irradiated at an angle 30° to the stack, composed of Al target and CR-39 (DOP) solid-state nuclear-track detector. These polymer sheets were etched in 6.25N NaOH solution at 70°C for 48 hours. The minor axes of the elliptic etch pits were measured by a Leitz Ortholux microscope. The measured projectile fragmentation cross-section for nuclei of chargeZ ranging from 21 to 25 is in approximate agreement with the calculated result from the semi-empirical nuclear fragmentation model after Wilson, Townsend and Badavi. The existence of trans Fe nuclei was noticed. The measured double-cone charge resolution was found to be 0.20e.

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

SummaryA 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.

Study of large fragments of uranium projectiles of energy 0.927 GeV/n in Al target

SummaryA stack consisting of CR-39(DOP) detector with 2.6 cm Al target was exposed to a238U beam of energy 0.927 GeV/n from LBL BEVALAC to study the large-fragmentation phenomena during U+Al interaction. The diameter distribution of the etch pits formed in the plastic detectors for the first three projectile fragments of chargeZF≥89 yields the partial cross-section data which is comparable to the data obtained from the cone length distribution. The present result on the partial cross-section is significantly higher than those expected from the abrasion-ablation model of Wilson, Townsed and Badavi (1987).

Studies on elemental charge-changing cross-section for relativistic U+Al collisions using CR-39 (DOP) detector

SummaryA search has been made on the charge-changing partial cross-sections by using 0.927 GeV/n238U ion from LBL BEVALAC projected at an angle 30° on27Al target and CR-39 (DOP) was used as analyser. The irradiated plastic sheets were duly etched for one hour in 6.25N NaOH solution and about 1680 cone lengths at both the surfaces of the CR-39 (DOP) sheets were optically measured. The cone length distribution exhibits the existence of U fragments in the charge range 84≤Z≤91 and the estimated partial cross-sections range from 60 to 400 mb. The present data are in accord with the fit to the extrapolated data of Binnset al.

Pershore made CR-39(DOP) as a 1.015 GeV/n197Au-ion detector

Pershore made CR-39(DOP) stack was exposed at a zenith angle of 30° by 197Au-ions of energy 1.015 GeV/n using LBL BEVALAC beam. The top of the irradiated plate of the stack has been etched in 6.25N NaOH solution at 70°C for one hour. About 1202 cone lengths were optically measured. The estimated etch rate ratio of the incident 197Au projectile beam in CR-39 has been found to be 27 ± 2. The result has been compared with earlier observations. The charge resolution of the detector has been estimated from the average of double cone lengths and has been found to have a value of (0.58 ± 0.03)e for 197Au-ions.