bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-energy muons in extensive air showers at 800 g cm−2
Authors: Chatterjee B. K. , Gopalakrishnan N. V. , Murthy G. T. , Naranan S. , Sreekantan B. V. , Rao M. V. Srinivasa , Tonwar S. C. , Vatcha R. H.
Published: April 2011

The following results on the low-energy (> 0.6 GeV and > 1.0 GeV) muons in air showers of size 105 to 2 × 107 at Ootacamund (800 g cm−2) are obtained: (1) The average total number of muons [Formula: see text] varies as Ne0.32 ± 0.2 for 105 < Ne < 106, and as Ne0.8 ± 0.15for 106 < Ne < 2 × 107. (2) In showers showing flat electron lateral structure, the [Formula: see text] variation with Ne is similar to (1). However, in steep showers, [Formula: see text] varies as Ne0.75 ± 0.15 in the whole size range 105 to 2 × 107. (3) "Muon-rich" showers of size < 106 have less energy in the electron–photon component compared to "normal" showers. No such difference is found for showers of size > 106. (4) There is a slight indication of a deficiency of muon-rich showers having a flat lateral distribution of electrons in the right ascension interval 15–21 hours for showers of size 106–107. A similar deficit of showers was observed by the Tokyo group for muon-rich showers in the same RA interval.
High-energy N particles in extensive air showers at 800 g/cm2
Authors: Chatterjee B. K. , Murthy G. T. , Naranan S. , Sreekantan B. V. , Rao M. V. Srinivasa , Tonwar S. C. , Vatcha R. H.
Published: April 2011

The results on high-energy N particles in EAS using a total absorption spectrometer for energy measurement are presented. They are compared with results from other experiments and calculations based upon plausible models of high energy interactions. (1) As expected, the NAP lateral distribution becomes steeper for particles of higher threshold energies. (2) Contrary to expectation, the lateral distribution becomes flatter with increasing shower size. The implication of this anomalous behavior in terms of interaction characteristics at energies > 1014 eV is briefly discussed. (3) For a given size, showers with steeper electron lateral distribution have more NAPs. (4) Except for the behavior of the lateral distribution as a function of size, all the other results can be explained in terms of models in which pT and inelasticity distributions are invariant and some fraction (~15%) of nucleon–antinucleon pair production is assumed.
Fluctuations of muon and electron numbers in EAS
Authors: Beer J. F. de , Holyoak B. , Oda H. , Wdowczyk J. , Wolfendale A. W.
Published: April 2011

Calculations have been made of the fluctuations in muon and electron numbers expected in air showers using different models of high-energy interactions and alternative assumptions about the mass composition of the primary particles. Comparison is made with the results of experiment, and it is concluded that the evidence concerning the suggested change in the mass composition of the primaries at energies above 1016 eV is inconclusive. Other consequences of fluctuations, in particular those in the lateral distribution of muons, are examined, and it is shown that such fluctuations can have a marked effect on the interpretation of experimental data.
The angular distribution functions of cascade electrons in iron and lead in the shower maximum
Authors: Ivanenko I. P. , Samosudov B. E.
Published: April 2011

The expressions for the angular distribution functions of cascade electrons in the shower maximum obtained by the authors are used to calculate these functions in iron and lead.
On the electron excess in electromagnetic cascade showers
Authors: Guzhavin V. V. , Ivanenko I. P. , Levitin A. E.
Published: April 2011

The equilibrium functions of the electron, positron, and photon distributions in cascade showers, including the positron annihilation Compton effect and δ electrons, are calculated. The results are used to estimate the electron excess in cascade showers.
The atmospheric electric field as a source of RF emissions from EAS, and some notes on bremsstrahlung
Authors: Charman W. N. , Jelley J. V.
Published: April 2011

One of us (W.N.C.) has suggested that the atmospheric electrostatic potential gradient may contribute to the generation of radio pulses from EAS. Three mechanisms, and their relative importance, are discussed: (i) the transverse charge separation induced in horizontal showers by the field gradient, (ii) the longitudinal charge separation induced in showers arriving from vertical directions, and (iii) radiation produced by the movement of ionization electrons, as they take up a drift velocity in the short interval prior to their loss by capture. It is concluded that while the effects of (i) are small under normal fair-weather conditions, they can become significant under disturbed conditions. The effects of (ii) are quite negligible. The contribution from (iii), however, is shown, for horizontal showers, to exceed that due to the charge-excess mechanism. The effect has a unique polarization.Following a recent letter by Rosenthal and Filchenkov, J.V.J. has reconsidered the problems of RF bremsstrahlung produced both by the shower particles themselves and by the δ rays along the tracks of the particles. It is concluded that in all cases the emissions from these processes are insignificant compared with the charge excess (Askaryan) and magnetic charge separation mechanisms (Kahn–Lerche) already discussed.
Theory of radio pulse production in extensive air showers
Authors: Allan H. R.
Published: April 2011

Radio emission by extensive air showers is analyzed in terms of the apparent particle accelerations as seen from the radio receiving aerial. The electric field is caused partly by the longitudinal motion of the shower particles, but principally by the transverse, geomagnetic deflections. The frequency range is controlled mainly by the way in which the shower builds up to maximum: above about 20 MHz the radio pulses are expected to become smaller through progressive loss of coherence.
Detection of radio emission from extensive air showers with a system of single half-wave dipoles
Authors: Vernov S. N. , Khristiansen G. B. , Abrosimov A. T. , Atrashkevitch V. B. , Volovik V. D. , Zaljubovsky I. I. , Solovjeva V. I. , Shmatko E. S.
Published: April 2011

Nine separate antennas for the detection of radio pulses from extensive air showers have been installed at the Moscow State University air shower array. Data are presented on the lateral distribution of the radiated power in individual showers.
Design of an array to record air showers of energy up to 1021 eV
Authors: Brownlee R. G. , Fisher A. J. , Goorevich L. , Kohn P. C. , McCusker C. B. A. , Ögelman H. B. , Parkinson A. F. , Peak L. S. , Rathgeber M. H. , Ryan M. J. , Winn M. M.
Published: April 2011

The design of an array to record air showers of energy up to 1021 eV is described. Each recording station uses two scintillator tanks spaced 50 m apart and generates a master pulse if [Formula: see text] particles pass through each tank in coincidence, n can be preset in the range 1 to 10. Pulse heights from each scintillator and the time of arrival of the shower front (to ±50 ns) are recorded on tape. The stations are designed to run for at least one week between servicings. Details are given of the scintillators, the circuitry (operated entirely from storage batteries), and the coincidence techniques.
Observation of EAS at airplane altitudes
Authors: Murakami K. , Kawasaki S. , Miyazawa T. , Kamata K.
Published: April 2011

Observations on EAS were performed at different altitudes from sea level to 11 km above sea level, and results on the density spectrum and the energy flow are given in this paper. The density of particles from 100 to 2 000 per m2 can be represented by a single-power law with exponent 2.55 ± 0.10 at 11 km and 2.65 ± 0.15 at 9.15 km above sea level, respectively. The average energy flow in the electron–photon component is found from the measurement of the transition m a 2–cm lead plate at airplane altitudes, at Mt. Norikura (2 770 m), and at sea level. The energy flow increases gradually with altitude.
Instrumental effects in the measurement of particle densities in extensive air showers
Authors: White G. M. , Prescott J. R.
Published: April 2011

Measurement of the parameters of EAS almost always requires repeated measurements of the densities of shower particles either at a single point, as in the determination of the density spectrum, or at many points simultaneously, as in the determination of the number spectrum. The apparent densities so obtained depend on the type of detector, on the energy and nature of the particles, and on the method of calibration.Calculations and experimental evaluation of apparent densities for different types of detectors are presented, and show, for example, that a cloud chamber and proportional counter sampling the same shower give apparent densities that differ by at least a factor of two. For plastic scintillators, the response depends on the thickness and on the energy of the incident particles.
The density spectrum of extensive air showers at 1 575 m and 4 300 m
Authors: Swinson D. B. , Prescott J. R.
Published: April 2011

The density spectra of extensive air showers at Albuquerque, New Mexico (1 575 m altitude) and Mt. Evans (4 300 m) have been measured using proportional counters. From 800 to 3 500 particles per m2, the integral density spectrum has a logarithmic slope of −1.43, and above this density the spectrum steepens continuously up to a density of 16 000 particles per m2. This is in good agreement with previous determinations of the density spectrum which indicated that the region of the spectrum in which the steepening occurs moves to higher densities with increasing altitude. At Mt. Evans, data of limited statistical accuracy indicate a spectrum that continues to densities of at least 60 000 particles per m2.
Momentum spectrum and charge excess of cosmic-ray muons at large zenith angles
Authors: Kasha Henry , Hawkins C. J. B. , Stefanski R. J.
Published: April 2011

A large-momentum spectrograph with 100 cm2 sr aperture was used to measure the momentum spectrum and charge excess of cosmic-ray muons at zenith angles close to 75°. Preliminary results based on a small sample of events agree well with available data.
Fine structure in the charge ratio of muons at large zenith angles
Authors: Kelly G. N. , MacKeown P. K. , Said S. S. , Wolfendale A. W.
Published: April 2011

Preliminary experimental results are presented of observations on the charge ratio of muons as a function of energy and of angle at large zenith angles found using the Durham horizontal spectrograph. There is some evidence for a maximum of the charge ratio at about 20 GeV, the magnitude of which increases with increasing zenith angle. Possible explanations of the effect are discussed.
The muon charge ratio at 80° to the zenith
Authors: Palmer N. S. , Nash W. F.
Published: April 2011

A brief description is given of a spectrograph recently constructed at Nottingham for the study of muons at large zenith angles. The instrument, situated at a latitude of 50 °N and 30 m above sea level, is at present orientated to accept muons incident in the geomagnetic north–south direction at a mean zenith angle of 80°. Experimental results are presented of the charge ratio among muons in the range of production energies 20–500 GeV. The results, which are found to be consistent with a constant or only slowly varying charge ratio over the entire energy range, are compared with the results of other workers and the predictions of some current theoretical models.
Experimental determination of the muon range–energy relation
Authors: Sheldon W. R. , Duller N. M.
Published: April 2011

Calculations of the zenithal distribution of cosmic-ray muons indicate the appearance of peaks at near-horizontal directions in the relative muon intensity I(θ)/I0 for Eμ > a few tens of GeV. The magnitude of the peak value of I(θ)/I0 increases monotonically with energy, representative values being 1.15 for Eμ > 50 GeV and 1.58 for Eμ > 120 GeV. Using this phenomenon, an independent evaluation can be made of the muon range–energy relation. Absolute measurements of the muon flux underground at zenith angles of 69° to 77° are compared to the calculated zenithal distribution to determine the muon range–energy relation in rock at 25–100 GeV. Suggestions are advanced for extending the energy range to a few thousand GeV and for making a purely experimental determination by utilizing magnetic spectrometer results in a context which would avoid the need to normalize the spectrometer data and would largely eliminate the problem of possible energy bias. The usefulness of these data in determining the pion attenuation length in the atmosphere is discussed.
Study of the properties of cosmic muons underground by means of a complex installation
Authors: Aglamasov V. A. , Gedevanishvili L. D. , Kasarov R. E. , Kirillov-Ugryumov V. G. , Kotov Yu. D. , Khuridze R. V. , Logunov V. M. , Rosental I. L. , Sakvarelidze I. I.
Published: April 2011

The main characteristics of a complex installation consisting of a shower system and an ionization calorimeter located under the shower system center at a depth of 130 m.w.e. are reported. Results of measurements of the energy spectra of bursts and electromagnetic cascades in the calorimeter are given. On the basis of the spectra obtained angular and energy distributions of muons going into an EAS compound are determined.
The Kolar Gold Fields neutrino project
Authors: Menon M. G. K. , Naranan S. , Narasimham V. S. , Hinotani K. , Ito N. , Miyake S. , Creed D. R. , Osborne J. L. , Wolfendale A. W.
Published: April 2011

In the underground laboratory at a depth of 7 600 ft in the Kolar Gold Mines, South India, five telescopes have been in operation for a study of the cosmic radiation which penetrates to such depths. In an exposure of 677 400 m2 sr h (for isotropic radiation) 46 events have been recorded. In seven events the particle trajectory has a projected zenith angle larger than 50°; these are interpreted as due to muons produced by neutrino interactions in the surrounding rock. From this the rate of neutrino-induced events is estimated to be about 3.1 × 10−13/cm2 s sr.The bulk of events with projected zenith angles less than 40° are interpreted as due to atmospheric muons, from considerations of the expected intensity and angular distribution. In between the above-mentioned two groups, there are 10 events in the zenith angle interval 40°–50° compared with an expected number of events of about two. The difference between the observed and expected rates in this angular interval is discussed.Recently, two new solid-iron magnet spectrographs have been installed at the same level, for measuring the momentum and sign of charge of the muons traversing the detector system. Each spectrograph has a maximum detectable momentum of 20 GeV/c and a collecting power of about 35 m2 sr for isotropic radiation.
The energy spectra of atmospheric and neutrino-induced muons
Authors: Craig R. , Osborne J. L. , Wolfendale A. W. , Young E. C. M.
Published: April 2011

The interrelation of the primary energy spectrum and the energy spectra of muons and neutrinos is examined. The energy spectra of "atmospheric" muons at ground level and underground are calculated for various assumptions about the form of the depth–intensity curve at great depths and alternative assumptions as to the composition and energy spectrum of the primary particles. The implications are discussed. Calculations have also been made of the energy spectrum of neutrino-induced muons underground. It is shown how the spectrum is sensitive to the form of the cross section for inelastic neutrino interactions and to the mass of the (hypothetical) intermediate boson.
A search for neutral particles at a depth of 20 m.w.e. underground
Authors: Vernov S. N. , Khrenov B. A. , Khristiansen G. B.
Published: April 2011

An experiment has been carried out to search for neutral particles producing secondary showers underground. No shower produced by a neutral particle has been detected. The upper limit of the flux of neutral particles underground has been evaluated.
The influence of the nuclear and atomic form factors on the muon bremsstrahlung cross section
Authors: Petrukhin A. A. , Shestakov V. V.
Published: April 2011

The cross section for the muon bremsstrahlung process is calculated as a function of the nuclear form factor in the Born approximation following the Bethe and Heitler theory. The influence of the nuclear form factor is greater than that taken by Christy and Kusaka. The simple analytical expression for the effect of the screening of the atomic electrons is found. The influence of a decrease in the cross section upon the interpretation of some experimental results is estimated.
Sky survey of high-energy cosmic X-rays and spectral information on sources in the Crab nebula, Cygnus, and Scorpius
Authors: Lewin Walter H. G. , Clark George W. , Smith William B.
Published: April 2011

A complete X-ray survey of the northern sky has been made in the energy range 20–100 keV. Spectra are given for Cyg X-1 and Tau X-1. Intensity ratios (Cyg X-1/Tau X-1) of 0.84 ± 0.10 and 1.30 ± 0.25 were derived in the 20–70 keV range from data obtained on July 19, 1966 and February 13, 1967, respectively. Observations on Sco X-1 and the Coma cluster show upper limits which are quite different from results reported by other groups.
Preliminary results of gamma-ray observations from OSO-3
Authors: Kraushaar W. L. , Clark G. W. , Garmire G.
Published: April 2011

A gamma-ray detector sensitive to energies greater than about 50 MeV has been placed in orbit on board the OSO-3 spacecraft. An analysis of about 28 hours of data yields an upper limit to the solar gamma-ray flux of about 10−4 photons/cm2 s and an upper limit of about 10−4 photons/cm2 s sr to the flux from the sky. The flux from the earth averaged over 4π sr is 0.1 ± 0.03 photons/cm2 s.
A fast optical Cerenkov system for directional studies of possible gamma-ray sources
Authors: Fegan D. J. , McBreen B. , O'Mongain E. P. , Porter N. A. , Slevin P. J.
Published: April 2011

The system observes pulses of light from the night sky, produced by small showers in the atmosphere. It uses two 90-cm f/0.5 mirrors in coincidence and with effective full field of view about 1°; but unlike previous systems of this kind it has a reduced integration time of about 3 ns and coincidence resolving time of 5 ns, the object being the selection of the fast collimated light cone originating from the high-energy early generations of the shower above 10 km rather than the slower, less directed, but more intense component from the vicinity of the maximum. The threshold energy for γ-rays showers is difficult to determine from the observed counting rate for proton showers, since the early development of the showers is different, but is believed to be in the vicinity of 1012 eV. Preliminary drift scans have been carried out in the winter of 1966–67 at a site 300 m above sea level near Dublin. Several drift scans have been carried out on the Crab nebula, 3C196, and 3C286; and individual runs on some other objects including a possible source of neutral primaries at about 1100 + 20 reported by Hesse et al. The Crab nebula results show an apparent positive effect which, if it is real, would correspond to a flux of about 10−10 photons/cm2 s, but the results are difficult to assess because of poor atmospheric conditions. Some other apparent positive effects have been observed, but none are significant statistically.
Cosmic X-ray measurements at Resolute
Authors: Green D. , Skirrow J. , Wilson B. G.
Published: April 2011

An upper limit of 6.9 ± 2.1 photons/cm2 sr s in the range 2–10 Å is reported for the X-ray flux above the polar atmosphere.
Neutron stars and cosmic-ray production
Authors: Melrose D. B. , Cameron A. G. W.
Published: April 2011

Recent investigations of the properties of neutron stars and of supernova explosions indicate that neutron stars should frequently be formed as supernova remnants. It now appears unlikely that any form of internal energy storage can play an important role in the production of X rays or cosmic rays. If mass infall onto a neutron star occurs at the upper limiting value allowed by radiation stresses, instabilities are likely to make the resulting mass infall, X-ray, gamma-ray, and cosmic-ray production very intermittent. It is shown that such a model may be able to account for many features of the Crab nebula: the energy input in electrons and ions, the character of the fast-moving light ripples or wisps, and the strong point source of ~50 MHz radiation.
Prompt gamma rays and X rays from supernovae
Authors: Colgate Stirling A.
Published: April 2011

The hydrodynamic origin of cosmic rays (Colgate and Johnson 1960) depends upon the shock ejection of the outer layers of the supernova. The increase in energy of the shock to c2 per gram occurs relatively deep within the star where the fraction, F, of mass external to this layer is 10−4. The relativistic shock wave continues to increase in strength in the decreasing density of the envelope. When the shock "breaks through" the surface denned as one Compton scattering mean free path at radius R, then the energy factor [Formula: see text]. The temperature in the proper frame of the shock is determined by the condition aT4 = 2γs2ρ0, where ρ0 is the initial rest density ahead of the shock. For a typical presupernova star, [Formula: see text], and polytrope of index 3, the temperature becomes (1.7–2) × 105 eV at the surface layer. Photons emitted from the moving surface layer will be Doppler-shifted from their mean proper frame value of 3kT to a final energy [Formula: see text].Photons originating in, and emitted from, the surface layer before the layer expands adiabatically will have the upper limiting energy. As adiabatic expansion of subsequent layers takes place, photons diffusing from greater depths will be emitted at sequentially lower energy. The total energy in the photon pulse from the surface layer becomes [Formula: see text] ergs, or 50 ergs/cm2 at the earth for a supernova within our galaxy. The time of emission becomes [Formula: see text] (Petschek 1967).
High-energy γ rays of cosmic origin
Authors: Anand K. C. , Daniel R. R. , Stephens S. A.
Published: April 2011

A stack of nuclear emulsions flown over Hyderabad (vertical geomagnetic cutoff rigidity 16.9 GV), India, under 6 g/cm2 of residual air has been used to set upper limits to the flux of γ rays of cosmic origin. The integral flux values obtained are 13 × 10−4, 6 × 10−4, 2.6 × 10−4, 1.4 × 10−4, 0.6 × 10−4, and 0.3 × 10−4 photons (em2 s sr)−1 for energies greater than 50 MeV, 100 MeV, 2 GeV, 5 GeV, 10 GeV, and 50 GeV respectively. Using these data and those of Kraushaar et al. (1965), it seems unlikely that cosmic-ray collisions in meta-galactic space can be an important source of electrons needed to explain the finite flux of cosmic X rays as due to the inverse Compton scattering of these electrons with photons of the universal blackbody radiation at 3 °K; such collisions would predict a flux of γ rays much in excess of the upper limits obtained in the energy region 50–100 MeV.
The electron energy spectrum in the flux of galactic cosmic rays
Authors: Rubtsov V. I. , Zatsepin V. I.
Published: April 2011

The primary cosmic-ray electron flux between 3.5 and 80 BeV has been measured with a system composed of scintillation detectors separated by a lead absorber, and with careful discrimination against protons and multiply-charged nuclei. Observations are presented for two balloon flights made in the summer of 1966 at a latitude corresponding to a geomagnetic cutoff rigidity of about 2.5 GV. The results obtained are well represented by a power-law spectrum of the form:[Formula: see text]between 3.5 and 80 BeV. A comparison is made with the results of other investigators.
Electron component in primary cosmic rays. I. Experiment
Authors: Danjo A. , Hayakawa S. , Makino F. , Tanaka Y.
Published: April 2011

The energy spectrum of electrons in the primary cosmic rays was measured at a location where the vertical geomagnetic cutoff rigidity is 11.5 GV, using a balloon-borne counter system. The differential spectrum was determined in the energy range from 13 to 50 GeV and is represented by a power law with exponent −2.4 ± 0.6. This result is consistent with a spectrum extending smoothly from lower energies with the same slope.
The composition of galactic cosmic rays
Authors: Reames D. V. , Fichtel C. E.
Published: April 2011

Recent measurements of low-energy galactic cosmic rays obtained on sounding rockets and satellites exhibit a composition different from that obtained for intermediate and high-energy radiation obtained at balloon altitudes. In particular the ratio of light to medium nuclei is observed to be 0.2–0.3 in the 50–100 MeV/nucleon interval as compared with values near 0.5 in the 200–500 MeV/nucleon region. Lower values of the ratios C/O, N/O, F/O, and odd-Z/even-Z are also found. In the light of these new measurements and of new measurements on the fragmentation cross sections for cosmic-ray nuclei in interstellar space, an attempt has been made to calculate the composition expected if similar source spectra are assumed. It is found that neither passage through a fixed amount of material nor an equilibrium condition (exponential path-length distribution) is adequate to explain the observed features. The effects of including other mechanisms such as rigidity-dependent escape from the galaxy and Fermi acceleration in interstellar space are evaluated.
Satellite measurements of the low-energy cosmic-ray Li, Be, B, C, N, O, F nuclei and their implications
Authors: Fan C. Y. , Gloeckler George , Simpson J. A.
Published: April 2011

The differential energy spectrum and chemical abundance of individual elements from lithium to fluorine have been measured near minimum solar modulation (June 1965 to March 1966) in interplanetary space on the IMP-III satellite. The spectra for Li, Be, and B are found to increase with decreasing energy below ~60 MeV/nucleon. The consequences of these results on the propagation and lifetimes of cosmic-ray particles are discussed.
Cross-section measurements of 6Li, 7Li, 9Be, 10Be, 10B, 11B formed by spallation reactions induced by protons in the energy range 150 MeV to 19 GeV in oxygen targets
Authors: Yiou F. , Citres J. Dufaure de , Frehel F. , Gradsztajn E. , Bernas R.
Published: April 2011

The determination of Li, Be, and B cross sections formed by spallation reactions induced by high-energy protons in C, N, and O targets is of interest for cosmic-ray physics and astrophysics. A mass-spectrometric method has been devised to measure the stable and long-lived isotopes 6Li, 7Li, 9Be, 10Be (τ = 2.5 × 106 yr), 7Be (τ = 54 d), 10B, 11B, formed in oxygen for proton energies of 0.15, 0.60, and 19 GeV. These results have been included in a program of calculations allowing us to determine the quantity of matter traversed by galactic cosmic rays of energy > 1.5 GeV/nucleon; the observed relative abundances are best fitted, in the slab approximation, by passage through 5.4 ± 1 g/cm2 of hydrogen.
Considerations affecting the estimation of cosmic-ray age
Authors: Shapiro M. M. , Silberberg R.
Published: April 2011

Previous investigations by Daniel and Durgaprasad on the ratios Be/B and Be/Li in the primary cosmic radiation exploited the decay of 10Be produced in space to deduce a confinement time for cosmic rays in the galaxy. They concluded that this "age" T is at least 50 million years, and thence inferred that the cosmic-ray nuclei are trapped in a volume much larger than that of the galactic disk. These conclusions depended upon the values of fragmentation cross sections available in 1962 to Badhwar, Daniel, and Vijayalakshmi. Recent values of the Orsay group, however, reduce the calculated rates of 10Be and 9Be production by an order of magnitude; and an analysis based upon the latest cross sections leads to the following conclusions: (1) The possibility that cosmic rays are mainly confined to the disk of the galaxy and that T ≈ 106 years is not excluded. (2) The fragmentation parameter for medium nuclei [Formula: see text] into light nuclei [Formula: see text] is revised from 0.48 (the value of Badhwar et al.) to 0.34. (3) The mean path-length of 2.5 ± 0.5 g/cm2 of Badhwar et al. is revised to 4 ± 1 g/cm2. (4) 7Be now appears to be the principal component of cosmic-ray beryllium (about 70 or 80%, depending upon the cosmic-ray lifetime).
High-energy galactic cosmic-ray composition measured in Gemini XI
Authors: O'Dell F. W. , Shapiro M. M. , Silberberg R. , Stiller B. , Tsao C. H. , Durgaprasad N. , Fichtel C. E. , Guss D. E. , Reames D. V.
Published: April 2011

An oriented nuclear-emulsion detector capable of time resolution was exposed in Gemini Flight XI to investigate the primary cosmic-ray nuclei above the earth's atmosphere. This was the first satellite exposure of an emulsion apparatus designed to collect 103 high-quality tracks of heavy nuclei under a negligible thickness of matter (0.07 g/cm2). Time resolution was obtained by moving a lower stack, consisting of emulsions of various sensitivities, with respect to a shallower, sensitive upper stack at the rate of 25 microns/minute. It was thus possible to separate the "useful" tracks–formed during the oriented portion of the flight–from those formed at other times. Preliminary data are presented on the relative abundances of individual chemical elements in the high-energy cosmic radiation above the earth's atmosphere. These measurements are compared to published results obtained on balloon flights at similar latitudes. When sufficient data become available in a later phase of this experiment, particular attention will be directed towards the Be and B abundances, the N and F content relative to C and O, and the relative number of iron-group nuclei compared to the lighter ones.
The energy dependence of the fragmentation parameters and mean free paths of cosmic-ray nuclei with
Authors: Cleghorn T. F. , Freier P. S. , Waddington C. J.
Published: April 2011

The fragmentation parameters and interaction mean free paths for VH- and H-type cosmic-ray nuclei have been measured as functions of energy in nuclear emulsions. It is found that they are essentially independent of energy over the range from 100 MeV/n to 30 GeV/n. The mean free paths of the secondary nuclei produced in observed interactions also have been measured. With two major exceptions, the values of the mean free paths are found to be consistent with an overlap model for nuclear interactions. The value obtained for the secondary L-type nuclei appears to be significantly shorter than that expected from the model calculations, while that for the primary VH nuclei appears to be significantly longer.
The charge distribution of the energetic very heavy nuclei in the primary cosmic radiation
Authors: Mathiesen O. , Long C. E. , Freier P. S. , Waddington C. J.
Published: April 2011

A fully digitized, semiautomated photodensitometer has been employed to study the detailed charge composition of primary cosmic-ray nuclei having [Formula: see text] detected in a stack of nuclear emulsions flown from Hyderabad, India under approximately 4 g/cm2 of residual atmosphere. One hundred and twenty nuclei heavier than phosphorus have been analyzed. These nuclei all had energies exceeding 7.1 GeV per nucleon and have had their charges measured with an accuracy estimated to be ± 0.4 of a unit charge. It has consequently been possible to resolve the individual charges and to determine the elemental abundances. The observed charge distribution has been corrected to the top of the atmosphere and compared with various cosmological abundance compilations. After deriving values for the fragmentation parameters in hydrogen, it is concluded that the data are consistent with the charge distribution predicted if an initially pure sample of iron nuclei had traversed some 4 g/cm2 of matter since the initial acceleration. The cosmologically abundant elements sulphur, argon, and calcium appear to be relatively absent from the source, while nickel is only present with the predicted abundance.
Charge and energy spectra of cosmic-ray nuclei with Z = 10–28
Authors: Bhatia V. S. , Chohan V. S. , Pabbi S. D. , Biswas S.
Published: April 2011

An improved method of charge determination of heavy primary cosmic rays of nuclear charge Z = 10–28 has been obtained by measuring the Fowler–Perkins parameter in less-sensitive G-2 and G-0 emulsions for the determination of the primary ionization. It is found that reliable measurements of the primary ionization can be made for ionizations as high as ~1 000 times minimum. The average errors in the charge determinations by this method were found to be about 0.5, 0.7, and 1.0 unit of charge for H1 (Z = 10–15), H2 (Z = 16–19), and H3 (Z = 20–30) groups of nuclei, respectively. This method has been applied to the study of the H1, H2, and H3 groups of nuclei in an emulsion stack exposed over Fort Churchill, Canada, on June 18, 1963 at 4.3 g cm−2 of residual atmosphere for 11.1 h. The results are based on an analysis of 340 nuclei with [Formula: see text]. The charge composition and relative abundances of the H1, H2, and H3 nuclei were obtained. The differential energy spectra of the H1, H2, H3, and [Formula: see text] groups of nuclei were determined in the energy interval 250–1 000 MeV/nucleon and integral fluxes for energy > 1 000 MeV/nucleon.
Low-energy cosmic-ray heavy nuclei during the time of solar minimum
Authors: Tamai E. , Tsubomatsu M. , Ogura K.
Published: April 2011

Nuclear emulsions were exposed at 2.3 g cm−2 atmospheric depth over Fort Churchill in 1965. These emulsions have been examined for the tracks of multiply-charged [Formula: see text] nuclei, with emphasis being paid particularly to those particles that stopped in the emulsions. Differential energy spectra of α particles and [Formula: see text], [Formula: see text]and [Formula: see text] nuclei were obtained in the energy interval 60–550 MeV/nucleon. They represent experimental results during the period when solar modulation effects were at a minimum. The fluxes of α particles and L, M, and H nuclei for energy intervals of 60–170, 100–400, 100–525, and 140–550 MeV/nucleon were found to be 20.9 ± 1.2, 2.4 ± 0.4, 4.8 ± 0.6, and 2.5 ± 0.4 particles m−2 sr−1 s−1, respectively. The results also show that the L/M and H/M ratios at the top of the atmosphere were 0.56 ± 0.16 and 0.34 ± 0.13 respectively, in the energy range from 140 to 350 MeV/nucleon. These values are appreciably greater than those observed at higher energies.
Interaction of cosmic electrons with relic radiation
Authors: Rosental I. , Shukalov I.
Published: April 2011

Results of the calculations of the interactions of metagalactic electrons with the relic radiation (the radiation is taken in the centimeter range) are given. The calculations have been made taking account of the expansion of the universe, space curvature, and X-ray absorption in the metagalaxy.
Cosmic rays in an evolving universe
Authors: Hillas A. M.
Published: April 2011

If the most energetic cosmic rays that have been detected are of extragalactic origin, and their sources were strong radio emitters, the radio-astronomical evidence suggests that the output from such sources must have been very much greater in the past than at present, varying roughly as t−3 over a long period. In this case, the importance of interactions between the universal flux of microwaves and intergalactic cosmic-ray protons and nuclei above 1015 eV is greatly increased, because of "red shifts" in the energies of the nuclei and the microwaves, and changes in density. The probable result is shown to be a steepening in the proton energy spectrum from a slope of –1.5 to –2.2 over the range 1016 to 1018 eV, as is observed, if the energy spectrum at production is always simply E−1.5.This could mean that the "ankle" in the observed spectrum near 3 × 1018 eV is related to the interaction mentioned, and is not a transition from galactic to extragalactic rays.Difficulties remain in accounting for the spectrum above 3 × 1019 eV.
The steady state of the primary and secondary components of cosmic rays
Authors: Cowsik R. , Pal Yash , Tandon S. N. , Verma R. P.
Published: April 2011

The steady state of primary and secondary components of cosmic rays has been calculated for a specific class of models. The results reproduce the observed experimental spectra down to ~50 MeV/n.
The energy spectrum of heavy nuclei above 10 GeV/nucleon
Authors: Koshiba M. , Suda E. , Takasaki F.
Published: April 2011

An experimental observation is made of the energy spectrum of heavy nuclei in the primary cosmic radiation using a large emulsion stack. The preliminary data so far accumulated indicate an exponent of 1.60 to 1.65 for the integral total-energy-per-nucleon spectrum.
A measurement of the energy fraction transferred to neutral pions in interactions of about 200 GeV
Authors: Fetisov I. N. , Morozov A. E. , Slavatinsky S. A.
Published: April 2011

The energy transferred to neutral π mesons in the interaction of nuclear-active particles with the lead nucleus was studied with an ionization calorimeter. The mean value of the energy transferred to π0 mesons is [Formula: see text]. The [Formula: see text] distribution is also presented.
The nature of the asymmetrical showers at an energy of 200 GeV and the features of the pion interaction
Authors: Erofeeva I. N. , Mishchenko L. G. , Murzin V. S. , Sarycheva L. I.
Published: April 2011

The nuclear interactions of nucleons and pions at an energy of 200 GeV have been studied using an ionization calorimeter, cloud chamber, and hodoscope units. It has been found that the showers which are asymmetrical backward have the two-peak angular distribution (on a log tan θ plot) and, in the center-of-mass system, the charged particles and neutrals appear in the remote and front hemispheres respectively. The showers which are asymmetrical forward are produced mainly by primary pions and are symmetrical in the system where the target mass is close to the pion mass. It is suggested that in the cosmic-ray energy range (e.g. at energies ~10 GeV), after interaction, a pion retains a considerable part of the primary energy, but may change its charge and be transmuted into a π0 meson. Such an assumption makes it possible to explain the considerable portion of the energy transferred to a photon in the pion interactions.
Inelastic cross sections of nucleons and π mesons in carbon and lead near 100 GeV
Authors: Alakoz A. V. , Bolotov V. N. , Devishev M. I. , Klimanova L. F. , Shmeleva A. P.
Published: April 2011

An experiment to measure the cross section for high-energy cosmic-ray neutrons and charged nuclear-active particle interactions with Pb and C nuclei has been carried out at an altitude of 2 000 m. Large spark chambers were used in a detector which selected neutrons and charged nuclear-active particles in the region of 100 GeV. The results are σπ(nPb) = (1.65 ± 0.17) barn, σπ(nC) = (0.204 ± 0.02) barn, σπ(πPb) = (1.53 ± 0.17) barn, σπ(πC) = (0.168 ± 0.017) barn.
Nuclear interactions at high energies
Authors: Eremenko Yu. A. , Lukin Yu. T. , Takibaev Zh. S.
Published: April 2011

Fifty jets recorded by an installation consisting of an ionization calorimeter and a cloud chamber have been analyzed. The mean energy of the primaries was 350 GeV and the mean number of charged secondary particles was [Formula: see text]. The target was made of carbon with a thickness of 0.08 interaction mean free path length. It is shown that in the energy region under investigation γc determined by Castagnoli's method is overestimated. It is also concluded that the distribution in Duller–Walker coordinates will give no information about the angles of emission of secondaries in their fireball rest system. If there are not more than two fireballs in the energy region [Formula: see text], then their mean mass is about 3 GeV. The distribution of 4-momentum transfers was measured; the mean value is of the order [Formula: see text]. It was possible to estimate the inelasticity coefficients by independent methods. The mean fraction of the energy transferred to π0 mesons was [Formula: see text] and to the charged mesons [Formula: see text], and the total inelasticity coefficient in the laboratory system was [Formula: see text].
The spectrum of γ rays in the energy range 1011 to 1013 eV at an atmospheric depth of 200 g/cm2, and pion generation in high-energy nucleon interactions
Authors: Apanasenko A. V. , Baradzei L. T. , Kanevskaya E. A. , Rykov V. V. , Smorodin Yu. A. , Solovyev M. V.
Published: April 2011

The problem of the existence of a change of slope in the γ-ray spectrum in the atmosphere is of considerable interest in connection with conclusions about the change in the character of the nucleon interaction. Up to now this problem has not been solved experimentally. In this report the γ-ray spectrum in the 1011–1013 eV energy range has been obtained using data from X-ray films and nuclear emulsions exposed on board an airplane at a pressure of 200 g/cm2. The total exposure was 425 hours∙m2. The energies of the electron–photon cascades initiated by γ rays were determined in the X-ray films by measuring the photometric densities of the black spots, and in nuclear emulsions by counting the electron tracks near the cascade axis. The integral spectrum has a power-law form with an exponent of 1.7–1.9. A change in slope in the spectrum was not found. Thus, a mechanism generating pions with energies proportional to the initial nucleon energies exists up to nucleon energies of ~1014 eV. The analysis of the accompaniment of γ rays by "families" shows that in one-third of the cases the energy of the most energetic π0 meson is at least five times that of the next π0 meson. In the remaining two-thirds of the cases the π0 mesons have comparable energies.
Checking of the hypothesis of the existence of the baryon passive state by calorimeter telescope and the energy spectrum of nuclear-active particles at mountain altitude
Authors: Erlykin A. D. , Kulichenko A. K. , Machavariani S. K. , Nam R. A. , Nikolsky S. I. , Yakovlev V. I.
Published: April 2011

In the Tien-Shan underground ionization calorimeter situated at a depth of about 13 m below the big ionization calorimeter (BIC), a search was made for jets which could be the continuation of nuclear cascades arising in BIC. The results obtained are used to check the hypothesis of the existence of the baryon passive state. Preliminary results on the spectrum of nuclear-active particles are given.
On the problem of high-energy nucleon–nucleus interactions
Authors: Gerasimova N. M.
Published: April 2011

On the basis of the analysis of high-energy jets performed in Cracow's Laboratory of High Energy Physics (Holynski et al. 1966) this paper proposes a new model of high-energy nucleon–nucleus interactions. The double maximum angular distribution of the high-energy jets has been explained as the result of the peripheral collision of the incident nucleon and one of the nucleons of the target nucleus and as the consequent central interaction of the now-produced "fast" fireball with another nucleon of the nucleus. The number of generated particles has been estimated from the usual thermodynamic equations. The conditions necessary for the secondary interaction (in the nucleus) of the π mesons produced in the decay of the "slow" fireball have been found. In the light of a comparison of our estimated results with experimental data a possible model of the fireball is discussed.
The inelastic n–p cross section at about 60 and 100 GeV
Authors: Bozóki G. , Fenyves E. , Christov C. , Ahababian N. , Betev B. , Kavlakov S.
Published: April 2011

The attenuation of penetrating shower-producing cosmic-ray neutrons in paraffin and graphite is measured with a counter hodoscope arrangement 2 925 m above sea level. The inelastic n–p cross section is determined by the CH2–C subtraction method. Results are presented for neutrons of mean energies about 60 and 100 GeV.
Composition of the September 2, 1966 solar particle event
Authors: Durgaprasad N. , Fichtel C. E. , Guss D. E. , Reames D. V.
Published: April 2011

Three Nike-Apache sounding rockets were launched from Fort Churchill, Manitoba, Canada to study the composition and the characteristics of the September 2, 1966 solar flare event. These launches occurred approximately 9, 16, and 36 hours following the event. Nuclear emulsions were used to study all the components, namely, the singly, doubly, and multiply charged nuclei emitted in the solar event and propagated within the solar system. The helium nuclei were separated from protons by using grain density and range measurements and from multiply charged nuclei by δ-ray density and range measurements. The multiply charged nuclei were identified as to charge from δ-ray density and range measurements. The energies of these nuclei were determined mainly from their residual range in the emulsion. The energy spectra measured in the event are much steeper than those reported for events in which the composition studies were made previously. The measured ratio of helium to medium (C, N, O, F) nuclei for energies above 12.7 MeV/nucleon in the first flight is 54 ± 8 to 1. This value is in agreement with the previous measurements, which strongly supports the ideas held that the acceleration mechanism does not appreciably alter the spectroscopically observed abundance of the solar photosphere.
A search for high-energy solar neutrons
Authors: Kim Chang Y.
Published: April 2011

Two stacks of G-5 emulsions on a directional device were exposed to cosmic rays at a ceiling altitude of 114 000 ft on July 30, 1966, at Fort Churchill (geographic latitude 58.8 °N and longitude 94.1° W). An attempt to measure the flux of high-energy solar neutrons has been made by inspecting the difference in flux from the direction of the sun and from the symmetrical direction about the zenith. The flux of neutrons has been determined by making observations on the tracks of protons recoiling from elastic collisions of neutrons with hydrogen nuclei present in the emulsions. The preliminary result of the experiment has shown that in the energy region of 20–100 MeV an excess of 1.1 × 10−2 neutrons cm−2 s−1 from the direction of the sun was observed. On that day the sunspot number was 63, and no major solar flare was reported.
Correlations of solar-flare electron events with radio and X-ray emission from the sun
Authors: Lin R. P.
Published: April 2011

The > 40-keV solar-flare electrons observed by the IMP III and Mariner IV satellites are shown to be closely correlated with solar radio and X-ray burst emission. In particular, intense type III radio bursts are observed to accompany solar electron-event flares. The energies of the electrons, the total number of electrons, and the size of the electron source at the sun can be inferred from radio observations. The characteristics of the electrons observed in interplanetary space are consistent with these radio observations. Therefore these electrons are identified as the exciting agents of the type III emission. It has been noted that the radio and X-ray bursts are part of the flash phase of flares. The observations indicate that a striking feature of the flash phase is the production of electrons of 10–100 keV energies.