bluuebunny/crossref_metadata_2025 huggingface dataset:
Note on multiple-core structure of the hadronic component of extensive air showers
Authors: Thielheim K. O. , Schlegel E. K. , Beieesdorf R.
Published: April 2011

Monte Carlo calculations on high-energy hadrons in extensive air showers have been performed, using various models of hadronic interaction and fragmentation. Frequencies of showers the hadronic component of which shows multiple-core structure are discussed in terms of primary particle and hadronic interaction parameters. The existence of a correlation between the primary mass composition and the frequencies of specified types of showers is demonstrated.
Observations of the atmospheric Cerenkov light associated with EAS at 5 200 m altitude
Authors: Krieger A. S. , Bradt H. V.
Published: April 2011

An array of four atmospheric Cerenkov light (CL) detectors has been installed on Mt. Chacaltaya (altitude 5 200 m) and operated in conjunction with the Bolivian Air Shower Joint Experiment (BASJE) for a period of several months. The CL detectors are located at radii of 15, 75, 100, and 300 m from the center of the BASJE array. Each detector consists of nine 5-in.-diameter photomultiplier tubes with a total sensitive area of 880 cm2. The angular response for incident photons is 65° FWHM about the vertical. The detector integration time is about 10−7 s, and the associated electronics has a logarithmic response of more than three decades. In the presence of background starlight, the minimum detectable photon pulse is about 104 visible photons/m2. The data exhibit the qualitative features expected for atmospheric CL emission. The average CL intensity varies approximately as N0.8 where the exact exponent depends upon the distance from the shower core. The fluctuations in CL intensity at a fixed distance from the core of EAS of fixed size are found to be greater than the experimental uncertainties. Therefore the observed fluctuations must reflect, in part, the inherent fluctuations in the development of EAS together with the effects of any mixture in the chemical composition of the primary cosmic-ray beam.
An interpretation of the bursts produced in the iron of the Haverah Park spectrograph
Authors: Orford K. J. , Turver K. E.
Published: April 2011

The bursts produced in the iron of the Haverah Park muon spectrograph are explained in terms of the electromagnetic and nuclear interactions of muons, nucleons, and pions in EAS. The data are used to confirm the form of the momentum spectra of muons at large distances from the shower core. The transverse momentum distribution necessary to account for the bursts attributed to nuclear-active particles is shown to be similar to that quoted by Earnshaw et al. (1967a).
Three-dimensional simulation of air showers. Core structures
Authors: Ogita N. , Rathgeber M. , Takagi S. , Ueda A.
Published: April 2011

Three-dimensional Monte Carlo simulations of extensive air showers were made with a model of nuclear interaction based essentially on the two-fireball model. Monte Carlo simulations were tried with primary protons of energy 106 and 2.5 × 105 GeV. Various quantities related to electrons, nuclear-active particles, and muons were obtained which enable us to get detailed information on the development of individual showers.Among various features so far simulated, those of core structures, in particular, are presented in great detail and discussed in connection with shower development. Within the framework of the fireball model the following main features were noted for the formation of multiple electron cores. The fraction of multicored events is strongly dependent on the primary energy, and decreases considerably with increasing height. These events were all initiated at high altitudes and none of them had high-density peaks with a separation of a few or more meters. High-energy nuclear particles play an important role in producing multicored events, but none of the peaks in multi-cored events were produced by a single γ ray.These features, in comparison with the experimental results, require the introduction of a large mean transverse momentum for nucleons, particularly at high energies [Formula: see text]. It seems likely that it increases with energy.
Nuclear-active energetic particles and extensive air showers at sea level
Authors: Murzina E. A. , Afanasiev A. A.
Published: April 2011

The particle number distributions of the showers accompanying nuclear-active particles of definite energies at sea level have been calculated. Comparison of the calculated and observed distributions makes it possible to conclude that the nuclear-active particles interact differently with nuclei depending on their energies.
The probability distribution functions for the numbers of electrons, muons, and pions, the cascade parameter S, and the energy carried by nuclear-active particles in EAS
Authors: Dedenko L. G.
Published: April 2011

The correlation matrix is analyzed for the following variates: the numbers of electrons, muons, and pions, the cascade parameter S, and the energy carried by nuclear-active particles in EAS. It is shown that large values of the correlation coefficients may be connected with the mutual dependence of several components in EAS. As an example the bivariate distribution figures for the cascade parameter S and the number of electrons and for the number of nuclear-active particles with energy above 103 GeV and the energy carried by such particles are presented. The whole analysis is given for showers generated by protons with an energy of 107 GeV at sea level.
The sensitivity of EAS characteristics to model parameters
Authors: Adcock C. , Oda H. , Wdowczyk J. , Wolfendale A. W.
Published: April 2011

The relationship between the primary energy of EAS and their ensuing characteristics has been analyzed for different models of high-energy interactions. Attention has been directed towards choosing a model such that there is agreement between the number spectrum of EAS and the assumption of a primary energy spectrum having a constant exponent at all energies. A possible model is one in which the multiplicity in high-energy interactions starts to increase faster than E1/4 with energy above a few times 1015 eV; other consequences of this mode are examined.
Application of birth-and-death processes to the cascade theory
Authors: Kobayakawa K. , Miono S.
Published: April 2011

A birth-and-death process taking immigration into account is considered. The complete solution of the equation governing the generalized birth-and-death process when the birth and death rates λ(t)and μ(t) and also the immigration factor ν(t) may be any specified functions of the time t is given. This solution can be applied to the fluctuation problem in electromagnetic showers. The distribution function of the number of particles at given depth t with given initial energy is derived. The results obtained are compared with recent experimental data, and the agreement is much better than in past theoretical works.
A long-distance coincidence radio-pulse experiment
Authors: Fegan D. J. , McBreen B. , O'Mongain E. P. , Porter N. A. , Slevin P. J.
Published: April 2011

Three radio receiving stations, operating at 45, 70, and 70 MHz center frequencies, have been set up for air shower detection. Separations are 10, 12, and 20 km between stations. Pulses are selected by combinations of antennae pointing towards magnetic west at large zenith angles. In 1 000 hours of operation, about 150 events have been observed in excess of the random expectation over the 10-km distance. Over the 12-km separation, no excess has been observed in 244 hours, but operation is restricted in this case by intervening hills to zenith angles less than 84°. Over the 20-km separation, a small excess is observed, which may be due to chance. In a series of subsidiary experiments, radio pulses have been correlated with night-sky Cerenkov detectors and a scintillation counter, and with receivers at 12, 35, and 500 Mc/s. From these experiments the rate of detection of cosmic-ray showers at a single station is believed to be at least 1 per hour, or about 5–10% of the radio pulses selected. Local radio coincidences at individual stations are in excess of random expectation, and the pulse-height spectrum for local events is steeper than would be expected for cosmic-ray events or interference pulses. The long-distance coincidences have not been established directly as cosmic-ray events, but are consistent with this interpretation.
Lateral and angular structure of electromagnetic cascades
Authors: Holynski R. , Jones V. , Pinkau K.
Published: April 2011

Measurements of electromagnetic cascades have been made in nuclear emulsions. Six cascades were measured in the Brawley stack (pure emulsion) and four in the SSS stack (lead–emulsion sandwich). The results show that the validity of the core approximation appears to range up to 7 × 10−2 radiation lengths, the core approximation of the angular distribution is valid to an angle of the order of 2°, and the sandwich structure of the SSS stack had no influence on the validity of the core approximation. A law for the mixed radial–angular distribution is given in one special case.
Some problems in the interpretation of underground cosmic-ray data
Authors: Barton J. C. , Stockel C. T.
Published: April 2011

Further data from observations made in a coal-mine are reported. The 20% discrepancy between the intensity at moderate depths underground and that deduced from the sea-level muon spectrum, already indicated by other work, has been confirmed. The possibilities of modifying the spectrum or the ionization-loss expression are discussed.Observations of the angular distribution strengthen the view that the exponent is rather higher than expected. This appears to imply that the K/π ratio must be quite high for muons of a few hundred GeV.The various reports of pairs and groups of muons at different depths underground are reviewed. Regarded as a cosmic-ray component muon pairs are less strongly attenuated underground than any other phenomenon (except neutrinos). The experimental results are discussed in terms of Greisen's semiempirical expression for the intensity of muons in extensive air showers.
Measurements of interactions of cosmic-ray neutrinos
Authors: Reines F. , Kropp W. R. , Gurr H. S. , Lathrop J. , Crouch M. F. , Sobel H. W. , Sellschop J. P. F. , Meyer B.
Published: April 2011

Measurements deep underground with a 165-m2 scintillation detector array give a number of events attributable to neutrino interactions in a massive rock target surrounding the detector. A large fraction of the events show unexpectedly small energy deposition in the detectors, and a number of events too complex to understand in detail are also observed. Therefore, until more detailed measurements can be made with an improved array now being installed, the rate can be stated only to lie between the limits 2.0 ± 0.5 × 10−13 and 4.5 ± 0.7 × 10−13 cm−2 s−1 sr−1.
Pair production by muons in the field of nuclei
Authors: Kelner S. R. , Kotov Yu. D.
Published: April 2011

The differential cross section for the production of electron pairs by muons has been obtained under the assumption that all particles are relativistic and that the Thomas–Fermi model can be used to evaluate the effect of screening. Analytical expressions have been obtained for the energy loss of muons by pair production for the two extreme cases of "no screening" and "complete screening". Results of numerical calculation of energy loss by this process are given as a function of muon energy, for rock with Z = 11.
Large-angle scattering of cosmic muons
Authors: Bugajev E. V.
Published: April 2011

Some processes of electromagnetic and photonuclear interactions of high-energy (109–1011 eV) muons leading to a large angular deflection of the incident muon are discussed. The upward flux of cosmic-ray muons at different depths underground is estimated.
Gamma-ray astronomy
Authors: Duthie J. G.
Published: April 2011

A brief review is presented of the predicted intensities of gamma radiation from celestial objects. This is followed by a discussion of the use of a balloon-borne spark chamber to measure these intensities and to study the background gamma-ray intensity at 2.8 atmospheric pressure over Texas.
Search for point sources of high-energy cosmic gamma rays
Authors: Delvaille J. P. , Albats P. , Greisen K. I. , Ögelman H. B.
Published: April 2011

A balloon-borne photographic spark chamber was flown at a pressure of 10 g cm−2 on 14 April 1966 from Holloman A.F.B., New Mexico. Upper limits were obtained on gamma-ray fluxes above 1 GeV from various discrete sources including Cyg A, Cas A, and the Crab nebula. Also a measurement was made on the average photon flux above 1 GeV from a portion of the galactic disk.
A balloon-borne X-ray survey of the central region of the galaxy
Authors: Boldt Elihu , Doong Henry , Serlemitsos Peter , Riegler Guenter
Published: April 2011

A balloon-borne X-ray survey of the galactic plane in the region of the galactic center was made from Australia during December 1966. The photon events recorded by a detector composed of a krypton gas proportional counter and a cesium iodide scintillation crystal are used to determine the spectrum of hard X-rays from the vicinity of Sgr XR-1.
Search for gamma rays from 3C 273 and M 87
Authors: Frye Jr. Glenn M. , Wang Chia Ping
Published: April 2011

Upper limits are set to the γ-ray flux above 50 MeV from 3C 273 and M 87 of 1.1 × 10−5 and 1.0 × 10−5 γ cm−2 s−1 respectively. The value for 3C 273 is below the minimum predicted from the matter–antimatter model for quasars of 3 × 10−5 γ cm−2 s−1. The vertical γ-ray flux at 2.5 mbar and 20° geomagnetic latitude is 1.6 × 10−3 γ cm−2 s−1 sr−1.
Differential energy spectra and intensity variation of 1-20 MeV/nucleon protons and helium nuclei in interplanetary space (1964-66)
Authors: Fan C. Y. , Gloeckler G. , McKibben B. , Pyle K. R. , Simpson J. A.
Published: April 2011

Measurements made in interplanetary space with a ΔE-range telescope on the OGO I and OGO III satellites and on the Pioneer 7 space probe showed that protons and helium nuclei in the energy range I–20 MeV/nucleon are present during "quiet times" in late 1964, in May–October–November 1965, and in August 1966. The intensities for both proton and helium nuclei are found to decrease with increasing energies. The spectra join those of the particles above 20 MeV/nucleon, which are known to be of galactic origin. For both protons and helium nuclei, the fluxes were higher in the period of minimum solar modulation in 1965 than in 1964. While in 1966 the helium flux decreased to its 1964 level, the proton flux showed a further increase over this period. It is believed that most of the particles observed during the period of minimum solar modulation were of galactic origin. As solar activity increases again, it seems that to the galactic low-energy fluxes, particularly for protons, there is added a steady contribution of solar origin.
The effects of the nature of matter traversed by cosmic rays on their composition and energy spectrum
Authors: Apparao M. V. K. , Ramadurai S.
Published: April 2011

The effects of the state of ionization of the matter traversed by cosmic rays, and those due to the presence of helium in it, have been studied. The amount of matter traversed by cosmic rays expressed in g/cm2 deduced by the usual assumption that the matter traversed is all neutral hydrogen can be erroneous. The presence of helium increases this value, and a considerable portion of the matter is helium. The ionized (partial) nature of the matter increases the ionization loss of cosmic-ray nuclei. The effect of this on energy spectra has been demonstrated.
Search for low-energy interplanetary positrons
Authors: Cline T. L. , Hones Jr. E. W.
Published: April 2011

Preliminary results of an experiment designed to detect and measure the intensity of interplanetary positrons of energy 0–3 MeV with the satellites OGO-I and OGO-III are outlined. Evidence for a statistically significant counting rate of detected positrons is presented, and the possibility that these particles represent a true primary component rather than a background effect, such as cosmic-ray induced secondaries in the detector, is considered. It is shown that the apparent intensity of low-energy positrons, assuming that value derived from their counting rate, would be consistent with an equilibrium charge ratio. This result would not be predicted with mechanisms involving the ionization of matter or the acceleration of electrons, but would be consistent with a strongly energy-dependent galactic trapping parameter allowing meson-decay electrons to slow down in great abundance, or with the existence of an independent source.
Electron component in primary cosmic rays. II. Theory
Authors: Danjo A. , Hayakawa S. , Makino F. , Obayashi H.
Published: April 2011

The energy spectrum of cosmic-ray electrons can be represented by a power law with a single exponent between 3 and 50 GeV, and a break in the spectrum due to the energy loss of electrons could appear at about 50 GeV or higher. It is necessary to reconcile this high value of the critical energy [Formula: see text] with the effective thickness of matter traversed [Formula: see text] as estimated from the positron flux) and with the small amplitude of anisotropy [Formula: see text]. Hence rather severe conditions are imposed on the properties of the region in which cosmic rays are stored. We have carried out an investigation of the two-component model for storing galactic cosmic rays, which consists of disk and halo components. Assuming the intensity ratio (η) of the halo to the disk components to be nearly unity, one can assign parameters explaining various properties of cosmic rays consistently. For the case of a vanishing halo component (η = 0), the mean scattering length for particle diffusion becomes about 1018 cm.
Path-lengths and source spectra of cosmic-ray helium and heavy nuclei
Authors: Biswas S. , Ramadurai S. , Sreenivasan N.
Published: April 2011

It is shown that assuming a source spectrum of the He nuclei of the form [Formula: see text] it is possible to explain accurately both the shape of the differential spectrum in the interval 40–1 000 MeV/nucleon and the 3He/(3He + 4He) ratios, and to determine the value of the residual solar modulation. This is not possible with other simple forms of source spectra. For medium nuclei[Formula: see text] it is found that a source spectrum of the above form can also explain both the observed Li/M ratios and the differential spectrum in the energy interval 100–1 000 MeV/nucleon using the same value of residual solar modulation. But there remains an excess flux of medium nuclei in the energy interval 40–100 MeV/nucleon to account for, so that it is necessary to consider a second source. Assuming that these nuclei traverse a very small amount of matter in space, the form of the second-source spectrum is obtained as [Formula: see text], the value of the index being the lower limit.
The charge spectrum of very heavy cosmic-ray nuclei
Authors: Fowler P. H. , Adams R. A. , Cowen V. G. , Kidd J. M.
Published: April 2011

The full text of this Invited Paper, which was presented at the Tenth International Conference on Cosmic Rays, held in Calgary, June 19–30, 1967, as paper OG-63A, is published in the October 1967 issue of the Proceedings of the Royal Society (London), Series A, pp. 39ff.
A two-way sidereal anisotropy
Authors: Nagashima K. , Ueno H. , Mori S. , Sagisaka S.
Published: April 2011

The sidereal time variation is analyzed using data for the ion chambers at Cheltenham and Christchurch for the period 1938–58 and for the meson and neutron components during the IGY. All the results derived from these three kinds of data support the existence of a two-way sidereal anisotropy, suggested by Jacklyn, which has two maxima of the cosmic-ray intensity in the directions of 8 h and 20 h S.T. (sidereal time).
On the nature of some anomalies in the cosmic-ray distribution
Authors: Chirkov N. P. , Krymsky G. F. , Kuzmin A. I.
Published: April 2011

Diurnal and semidiurnal variations of the data from the worldwide network of neutron monitors during 1958 are analyzed using the receiving-vector method. It is shown that there exists an "antisymmetric" diurnal variation, i.e., a variation with opposite phases in the northern and southern hemispheres. After correction for the distortion due to the geomagnetic field, it is found that this variation has an amplitude of 0.03% and an hour of maximum at 21.5 hours in the northern hemisphere. If the variation is due to cosmic-ray screening in the interplanetary magnetic field, this field must have a slope of 7° with respect to the solar equatorial plane.
The electromagnetic radiation associated with the energy dissipated by cosmic rays in interstellar hydrogen
Authors: Balasubrahmanyan V. K. , Boldt E. , Palmiera R. A. R. , Sandri G.
Published: April 2011

Evidence is presented for an interstellar cosmic-ray spectrum that arises from a source function which is a power law in kinetic energy per nucleon (αE−2.5) and which gets modified by the energy degradation of particles that traverse an average of 3–6 g/cm2 of interstellar matter, with paths distributed according to a steady-state model (Cowsik et al. 1966).For the interstellar spectrum inferred, the Coulomb interactions of cosmic rays with the hydrogen atoms of HI clouds are found to supply the correct energy input for maintaining at equilibrium the observed gas temperature of 102 °K. These interactions give rise to a high electron concentration (~10−1 cm−3), consistent with observations. The galactic backgrounds of X rays and Hα radiation are shown to be measures of the electromagnetic interactions of cosmic rays with the hydrogen atoms of HI clouds.
Pions in the cosmic-ray nuclear-active flux at an altitude of 3 250 m above sea level
Authors: Avakian V. V. , Pleshko M. P.
Published: April 2011

An experiment has been carried out at an altitude of 3 250 m above sea level (Mt. Aragats, Armenia) by means of a magnetic mass spectrometer. The results show the analysis of nuclear-active particles which produce interactions occurring in a series of generators over the magnetic mass spectrometer. The ratio of charged to neutral nuclear-active particles is found to be 1.68 ± 0.16, the ratio of pions to nuclear particles 0.22 ± 0.08, and of pions to protons 0.38 ± 0.13.
The 1966–67 increase in solar cosmic-ray activity
Authors: Masley A. J. , Goedeke A. D.
Published: April 2011

A significant increase in solar cosmic-ray activity began in early 1966. During the period from March 1966 to June 1967, 14 events were observed. This can be compared to one event in 1964 and one event in 1965. Events in 1966 occurred on 24 March, 7 July, 28 August, 2 September, and 14 September. Events in 1967 include those of 28 January, 2 February, 7 February, 13 February, 11 March, 23 March, 23 May, 28 May, and 6 June.The 2 September 1966 event, reaching a maximum of 13 dB (~105/cm2 s > 2 MeV), was the largest observed since July 1961. The 23 May 1967 event, with 11 dB, reached maximum absorption 35 hours after first observation. The 28 January 1967 event exhibits several interesting features. There is an apparent lack of a visible flare. Low-energy particles were observed for several hours before neutron monitors observed an event in excess of 15%, representing a low-energy precursor to the high-energy event. Details of these events are discussed. Parameters related to acceleration and propagation such as delay times and intensity–time profiles, effects related to other geophysical phenomena, and comparisons with satellite observations are also included. This paper is based on 30-MHz riometer observations at the Douglas Observatories located at McMurdo, Antarctica, and Shepherd Bay, N.W.T., Canada (80° geomagnetic latitude). The measured absorption is proportional to the square root of the particle intensity.
The results of simultaneous measurements of the cosmic-ray intensity over the Antarctic and Arctic
Authors: Vernov S. N. , Charakhchyan A. N. , Charakhchyan T. N. , Stozhkov Yu. J.
Published: April 2011

The results of the analysis of data obtained from measurements carried out by means of regular stratospheric launchings of cosmic-ray radiosondes over the Murmansk region and the Antarctic observatory in Mirny in 1963–66 are presented. The problem of the anisotropy of the primary component of low-energy cosmic rays and of temperature effects on the cosmic-ray intensity in the atmosphere are discussed.
Forbush decreases at different periods of the solar cycle
Authors: Imazhanova K. , Kolomeets E. V. , Musabaev M. , Pivneva V. T.
Published: April 2011

An analysis of Forbush decreases occurring at different periods of the solar cycle has been carried out using data from the worldwide network of stations registering the neutron component of the cosmic-ray intensity. The changes of energy spectrum of Forbush decreases have been investigated for the interval from 1957 to 1965, and also the dependence of the decrease and recovery times on particle energy and solar activity.
Cosmic-ray proton and helium spectra and solar modulation effects in the new solar cycle measured with a four-element counter telescope
Authors: Ormes J. F. , Webber W. R.
Published: April 2011

In the summers of 1965 and 1966 we have continued our studies begun in 1963 on the primary proton and helium spectra and the effects of solar modulation. Data are available from four additional balloon flights at Fort Churchill using the earlier version of the Cerenkov-scintillation counter telescope (Ormes and Webber 1966), and a new four-element double-scintillation (dE/dx), Cerenkov-scintillation + range telescope. This latest telescope employs pulse-height analysis on both dE/dx counters and the Cerenkov-scintillation counter. Various consistency requirements may be set between pulse heights. These serve to reduce background effects by an order of magnitude over the previous system. The geometrical factor of the telescope is 55.4 sr cm2. The results reported here will cover the proton and helium spectra from 100 MeV/nucleon to 2 BeV/nucleon and their time variation. They will show that the fractional changes in the differential proton spectra can be represented by (rigidity)−1 both before and after the sunspot minimum and that there is no evidence for any hysteresis effects between protons of 100 MeV to 2 BeV and energies to which neutron monitors respond.
Investigation of long-time cosmic-ray variations
Authors: Salimzibarov R. B. , Sokolov V. D. , Skryabin N. G. , Klimenko V. V. , Shafer Yu. G.
Published: April 2011

During 1958–66 the flux and mean ionization chamber response of cosmic-ray particles were measured. On the basis of the experimental data the 11-year variations of the flux and of the charge composition of cosmic rays, and the annual variations, have been investigated.
Change of the main characteristics of cosmic-ray variations and interplanetary space with the cycle of solar activity
Authors: Kuzmin A. I. , Altukhov A. M. , Krymsky G. F. , Krivoshapkin P. A. , Skripin G. V. , Filippov V. A. , Chirkov N. P. , Shafer G. V.
Published: April 2011

Changes of the characteristics of the solar-diurnal variation and Forbush decreases of cosmic rays with the solar activity cycle are analyzed. It is shown that the energy spectrum of the solar-diurnal variation is well described by the Krymsky diffusion mechanism spectrum with b parameters of 59, 40, and 30 BeV for high, middle, and low solar activity levels, respectively. The Forbush-decrease spectrum is described by a power law with exponents −0.8 and −0.6 during high and low solar activity. These changes are interpreted to be the result of a decrease of solar wind velocity and a decrease of the mean strength of the interplanetary magnetic field with a decrease in solar activity.
Cosmic-ray produced 59Ni and its astrophysical and geophysical implications
Authors: Hasegawa H. , Yamakoshi K. , Noma M. , Maihara T.
Published: April 2011

The processes for the production of 59Ni in meteorites and in micrometeorites have been studied. For large bodies, 59Ni nuclei are produced by galactic cosmic rays through (i) the spallation reaction of 60Ni, 63Cu, etc., and (ii) radiative capture of secondary neutrons slowed down in meteorites: 58Ni(n, γ) 59Ni. For small bodies, the contribution of solar cosmic rays is important. The main contribution comes from the (α, n) reaction, induced by solar cosmic-ray α particles: 59Fe(α, n)59Ni, and the secondary contribution is due to solar cosmic-ray protons: 60Ni(p, pn)59Ni and 59Co(p, n)59Ni. From the use of solar cosmic-ray data, the 59Ni activity in micrometeorites has been calculated. Under conditions of radioactive equilibrium, the 59Ni activity is 220 d.p.m./g Ni, if 93% of the micrometeorites are composed of stone and 7% of iron. The contribution of solar cosmic-ray protons is 15 d.p.m./g Ni, giving a total of 235 d.p.m./g Ni. Experimental information in the 59Ni sedimentation rate will determine the fallout rate of extraterrestrial nickel–iron. Measurement of the 59Ni activity in pelagic clay, dated by the Th–Io method will provide information concerning the variation of solar activity, as represented by the solar cosmic-ray intensity, over the last few hundred thousand years.
Some general properties of radiation processes as related to "secondary" cosmic rays
Authors: Jones Frank C.
Published: April 2011

The individual processes of synchrotron radiation and inverse Compton scattering produce quite different photon spectra for electrons of a given energy. However, an inverse power-law spectrum of electrons, j(γ) = k′γ−m, will produce a photon spectrum N(α) = Kα−(m+1)/2 for either process. The explanation for this lies in the fact that both individual radiation processes produce spectra of the form N(α) = F(αc/αc)(αc)−n where the characteristic energy αc is proportional to some power of the electron energy and contains all of the dependence on the electron energy that the spectrum exhibits. This form of the spectrum coupled with an inverse power-law electron spectrum produces the desired result. An investigation reveals that other radiation and secondary particle production processes possess this form of spectrum. This gives a very general explanation for the well-known fact that secondary particles, even those several generations removed from the primary cosmic rays, exhibit inverse power-law spectra.
Cosmic-ray flux variation with height in the atmosphere
Authors: Chow B. S. , Wu K. K. , Simpson N. , Hopper V. D.
Published: April 2011

Analysis of emulsions exposed to cosmic radiation at atmospheric depths between 10 and 40 g/cm2 at λ = 47 °S geomagnetic on 11 December 1964 shows that there is little variation with altitude in proton flux in this altitude range. However, the total star production rate increases with increasing atmospheric depth but with a smaller slope than that measured by Geiger counter. Preliminary results obtained from exposures made in November 1965 at 8.5, 28.4, and 58 g/cm2 show that the values of proton flux at 8.5 and 58 g/cm2 are lower than that at 28.4 g/cm2. A study of the rate of production of stars at λ = 43° S and 9 g/cm2 over the period April 1962 to September 1966 shows some correlation with the ground-based neutron monitor count rate. The proton flux at the top of the atmosphere at latitude 47° S is estimated as 900 ± 100 protons/m2 sr s.
Gamma rays and high-energy neutrons in the atmosphere
Authors: Apparao M. V. K. , Daniel R. R. , Joseph George , Gokhale G. S. , Lavakare P. J. , Sunderrajan R.
Published: April 2011

In continuation of our earlier experiments studying the emission of solar neutrons, we have now developed detector systems which respond to γ rays of energy 1–5 MeV and neutrons of energy [Formula: see text]. The two detectors are almost identical. Each consists of a CsI (Na) crystal (B) of diameter 3.8 cm, completely enclosed in a tapered cylinder of plastic scintillator (A) operated in anticoincidence; the crystals have thicknesses of 2.4 and 1.2 cm respectively. A balloon carrying these detectors was flown on March 16, 1967 over Hyderabad, India (vertical cutoff rigidity 16.9 GV) and floated at a ceiling altitude of 6.0 mb for 1 hour. In addition to γ-ray and neutron events (AB), events A and AB were also continuously monitored throughout the flight. Pulses corresponding to 1–5 MeV in the 2.4-cm crystal (γ rays) and 6–40 MeV in the 1.2-cm crystal (high-energy neutrons) were analyzed by a 64-channel pulse-height analyzer. On the basis of the pulse-height distributions and γ-ray efficiencies in the two crystals, we attribute events of 1–5 MeV energy from the thicker crystal to γ rays and those > 10 MeV in energy from the thinner one to stars produced by high-energy neutrons [Formula: see text] in the crystal. Atmospheric growth curves for γ rays and neutrons have been obtained; these growth curves as well as those for events A and AB show the normal features of the Pfotzer maximum, steady decreases up to the ceiling altitude, and a constant counting rate at ceiling. The atmospheric counting rates at ceiling altitude give for γ rays of energy 1–5 MeV a flux of ~1 photon per cm2 s and for neutrons of energy [Formula: see text] a flux of ~0.1 neutron per cm2 s. No evidence for a solar component in either channel was found.
Secondary spectra of electrons and photons in the atmosphere
Authors: Beuermann K. P. , Wibberenz G.
Published: April 2011

Electrons and photons of the secondary cosmic radiation have been separated from the other components by means of their shower development in a lead scintillator arrangement. Measurements have been performed at 4.5 GV geomagnetic cutoff at atmospheric depths of 760 g/cm2 (in vertical direction between 12 MeV and 20 GeV, inclined at 36 °N between 12 MeV and 1 GeV, and inclined at 49° and 59 °N between 70 MeV and 1 GeV) and 955 g/cm2 (in vertical direction between 12 MeV and 1 GeV). The results can be characterized as follows.1. For the energy range covered at both locations and/or at different zenith angles there is no significant change in the spectral shape.2. Both the photon and the electron spectra steepen gradually, the exponent of the differential power-law spectrum E−n assuming a value n = 2.8 for energies above 1 GeV.3. The photon/electron ratio is in good agreement with the ratio of the track-length distributions calculated by Richards and Nordheim for electromagnetic cascades in air.4. A cosnθ law is a poor approximation to the angular distribution of the integral intensities above 100 MeV. A better fit is obtained from calculations taking into account the relative contributions of π0's and muons to the electron and photon intensities at a given zenith angle θ.
Contributions to the counting rate and the temperature dependence of neutron monitors
Authors: Harman C. V. , Hatton C. J.
Published: April 2011

The temperature effect on the counting rate of neutron monitors is a result of (a) pion and muon interactions in the monitor, (b) muons stopping in the monitor, and (c) pion links in the atmosphere. The contributions made by (a) and (b) to the counting rates of IGY and NM64 monitors have been calculated, and it is shown that whereas the contributions from pion and muon interactions are comparable in the two monitors there are fewer stopping muons in the NM64 monitor. The resulting temperature effect for the IGY monitor is a factor of 1.2 ± 0.3 larger than that predicted by Dorman, while for the NM64 monitor the factor is 0.85 ± 0.2.Using a multiple regression analysis the temperature effects for the IGY and NM64 monitors have been determined for the period 1962–65. The results show that the temperature effect in the IGY is larger than that predicted by Dorman by a factor of 1.57 ± 0.10. The corresponding value for the NM64 monitor is 1.20 ± 0.13. These values are somewhat higher than those expected theoretically; however, the observed ratio of the temperature effect in the NM64 monitor to that in the IGY of 0.76 ± 0.09 agrees well with the theoretical value of 0.7 ± 0.2.
Observations on cosmic-ray variations during cold-front perturbations
Authors: Fazzini M. C. , Galli M. , Guidi I. , Randi P.
Published: April 2011

Peculiar small variations of the total ionizing component of cosmic rays have been observed during atmospheric cold-front perturbations. These variations have an amplitude of the order of 1% and a duration of a few quarters of an hour. The possibility of an effect of temperature or of atmospheric electricity is discussed.
Latitude survey of the frequency of multiple events in an airborne neutron monitor
Authors: Kent D. W. , Coxell H. , Pomerantz M. A.
Published: April 2011

To obtain information concerning the energy dependence of the average number of evaporation neutrons produced by a nucleon incident on a neutron monitor, measurements were obtained with a multiplicity detector operated during the epoch of solar minimum aboard the U.S. Naval Oceanographic Office worldwide survey aircraft (Project MAGNET). The latitude and altitude variations of events with different multiplicities were determined. The data indicate, for example, that over the range of threshold rigidity 3–13 GV, the latitude effect for threefold events is 1.7 ± 0.1. This is intermediate between the corresponding results obtained with the conventional neutron monitor and a semicubical meson telescope that was also carried aboard the aircraft. The atmospheric attenuation length for high-multiplicity events is less than for events in which a single neutron is detected, consistent with a slightly increasing inelastic nucleon–nucleus cross section as the nucleon energy increases toward 1 GeV.
The relation between latitude and solar-cycle variations in the neutron-monitor mass-absorption coefficient
Authors: Forman Miriam A.
Published: April 2011

The differential mass-absorption coefficient for rigidities between 2 and 15 GeV/c for IGY-type neutron monitors at sea level and at 500 mm Hg pressure altitude has been calculated from the variation of the neutron-monitor intensity and mass-absorption coefficient with cutoff rigidity. Combined with six sea-level surveys of neutron-monitor intensity between 1954 and 1962, and assuming no time variation in the neutron-monitor mass-absorption coefficient above 15 GeV/c cutoff, the calculated differential mass-absorption coefficient implies a solar-cycle variation of about 0.04%/mm Hg at 2 GeV/c cutoff rigidity at sea level.
A focusing X-ray telescope for use in the study of extraterrestrial X-ray sources in the energy range 20–140 keV
Authors: Llndquist T. R. , Webber W. R.
Published: April 2011

We have designed and tested a focusing X-ray telescope with an angular resolution (FWHM) of 1.0° for the study of extraterrestrial X-ray sources in the energy range 20–140 keV. The telescope's lens is an array of rock salt crystals (each of which is approximately one inch square), mounted on a 6-ft-diameter paraboloidal frame. The lens is located 9.5 ft above a 2-in.-diameter NaI crystal and PM tube (which measures the energy of the incident X ray). X rays passing through the salt crystals undergo a 2θ deflection if the Bragg condition for reflection, nλ = 2d sin θ, is approximately satisfied. Optimum thickness and effective energy bandwidths for such reflections have been determined for energies in the telescope's operating range. The area-efficiency product of the lens is approximately 8 times the NaI crystal area from 20 to 40 keV, giving a real improvement in the signal-to-background ratio. Crystals more nearly perfect than rock salt offer the possibility of increased gain over narrow energy intervals. Polarization measurements of the incident X rays may also be made.
The anomalous pulse spectrum of water Cerenkov detectors
Authors: Maslin G. C. , Tuever K. E. , Walton A. B.
Published: April 2011

An explanation for the anomalous pulse spectra of water Cerenkov detectors reported by Allan et al. (1966) is presented, which is based upon the electromagnetic interactions of muons of the cosmic-ray beam.
Multiplicity measurements on the IGY neutron monitor at Jungfraujoch
Authors: Debrunner H. , Walther U.
Published: April 2011

A multiplicity meter has been attached to the Jungfraujoch IGY neutron monitor. Preliminary results, obtained during the months October–December 1966, are presented. Also the influence of coincidences and dead-time losses, which are important for stations with high counting rates, is discussed.
A Nuclear Spin Relaxation Study of the Spin–Rotation Interaction in Spherical Top Molecules
Authors: Courtney James A. , Armstrong Robin L.
Published: April 2011

The spin–lattice relaxation time T1 of the 19F nuclei was measured in gaseous samples of CF4, SiF4, GeF4, and SF6 at room temperature for densities from 0.015 to 20 amagat. In each case T1 was observed to pass through a minimum for some density less than 0.50 amagat. In addition, T1 was measured in the extreme narrowing region for SF6 at 238, 265, 293, 313, and 349.5 K.. The spin–rotation interaction provides the dominant relaxation mechanism in all cases. The data are analyzed on the basis of the assumption that the collision modulated spin–rotation interaction may be described by a single correlation function which is a simple exponential function of time. Values of an effective spin–rotation constant and a cross section for molecular reorientation are obtained for each gas. Assuming the validity of the model used to analyze the relaxation data, the combination of nuclear magnetic relaxation results with molecular beam measurements yields more accurate values of the anisotropic spin–rotation constant Cd than have been previously available.
Weak Radiative Decays of Hyperons in the Pole Model
Authors: Yakimiw E. , Jakimiw G.
Published: April 2011

It is found that the pole model which includes the decuplet pole contributions in the weak radiative decays of hyperons fails to give the correct sign of the Σ+ → pγ asymmetry parameters α, although the magnitude of the decay rate and of α are consistent with the present experimental data. This conclusion holds in the Rarita–Schwinger formalism. Earlier calculations are incorrect due mainly to an error in the spin-3/2 propagator used in the theory, and inconsistencies in the SU(3) phase convention.
Characteristics of Cosmic Ray Diurnal Variation from Deep River Neutron and Meson Data and Temperature Effects
Authors: Agrawal S. P. , Ananth A. G. , Rao U. R.
Published: April 2011

From an extensive analysis of Deep River meson data for over 5 years, new temperature coefficients have been derived for correcting the meson data. It is shown that meson data corrected using new coefficients yield values of diurnal and semidiurnal anisotropy consistent with those obtained from neutron monitors. Using the temperature-corrected meson and neutron data, the upper cutoff rigidity beyond which the diurnal variation ceases is shown to vary with solar cycle showing a minimum of about 35 GV during the Quiet Solar Year of 1965, and a maximum of ≈ 125 GV during 1968–1969.
Second-Order Raman Spectra of Fluorites. II. Lattice Dynamical Analysis
Authors: Krishnamurthy N. , Soots V.
Published: April 2011

The second-order Raman spectra of CaF2, SrF2, BaF2, and PbF2, reported in an earlier publication, have been correlated to two-phonon density of states distributions calculated on the basis of the shell model of Woods et al. In the case of SrF2 and PbF2 the pertinent model parameters were first calculated from existing optical and elastic data for these crystals, while for CaF2 and BaF2 existing parameters, as determined by inelastic neutron scattering, were used.The calculated density of states distributions showed a general agreement with the observed spectral profiles, but agreement in detail was not precise, indicating a need to use more complicated anharmonic lattice models and to adjust the values of the model parameters.
The ν1 Band of Carbon Dioxide in Pressure-Induced Absorption. II. Density and Temperature Dependence of the Intensity; Critical Phenomena
Authors: Mannik L. , Stryland J. C.
Published: April 2011

The ν1 band of gaseous carbon dioxide has been studied in pressure-induced absorption at temperatures of ~ 190, ~ 300, and ~ 470 K, over a density range from 0.5 to 300 amagat, and with path lengths from 0.007 to 56 m. The observed temperature variation of the binary absorption coefficient can be satisfactorily accounted for only by adding a quadrupole–quadrupole interaction term to the usual Lennard–Jones model for the inter-molecular potential. The band profile is in agreement with the theory of quadrupole-induced absorption. There is some increase in the intensity of the band near the critical point due to the divergence of the correlation length. A very marked increase in the intensity is possibly prevented by the "cancellation effect".
Systematic Trends in Atomic Oscillator Strengths: The Helium Isoelectronic Sequence
Authors: Cohen M. , McEachran R. P.
Published: April 2011

Electric dipole oscillator strengths (f values) have been calculated for a large number of singlet and triplet S–P, P–D, and D–F transitions in the helium isoelectronic sequence through O+6. The analytical orbital wave functions employed were of frozen-core type, and generally produce very good agreement between length and velocity values of the calculated oscillator strengths. A conspicuous exception occurs in many cases where the principal quantum number remains unchanged in the transition, and the more reliable dipole length values have been adopted for such transitions. The smooth variation of the calculated f values as functions of the inverse of the nuclear charge Z provided a sensitive check on the accuracy of the computations and indicated a considerable number of P–D transitions where the velocity values seemed the more reliable. Wherever comparison data are available, our calculated oscillator strengths are in excellent agreement with the most accurate values; in other cases, the absolute uncertainty in the f values should in no case exceed 5%.
Vibrational Analysis of the 2800 Å Band System of para-Dibromobenzene
Authors: Japar S. M.
Published: April 2011

The 2800 Å band system of p-dibromobenzene has been photographed under high resolution and an extended vibrational analysis has been carried out. The analysis is not inconsistent with the assignment of the system to a 1B2u ← 1Ag transition, by analogy with other p-dihalogenated benzenes. The observed spectrum can be explained in terms of a number of strong type-B vibronic bands and a considerably smaller number of type-A vibronic bands. The extensive sequence structure is adequately accounted for, and can be related to observations on other halogenated benzene molecules. Thirteen ground state and nine excited state fundamental vibrational frequencies have been assigned.
Extended Temperature Range Measurements of Thermoluminescence due to Gd3+ Ions in CaF2
Authors: Ward R. W. , Whippey P. W.
Published: April 2011

Experimental thermoluminescence glow curves of CaF2 crystals containing several different concentrations of Gd3+ have been measured over the temperature range 4.2–600 K. Hole activation energies have been determhined by a least squares fit to the general order kinetics equation. The limitations of this type of analysis are discussed.