bluuebunny/crossref_metadata_2025 huggingface dataset:
Interplanetary and solar electrons of energy 3–12 MeV
Authors: Cline T. L. , McDonald F. B.
Published: April 2011

This paper reviews two topics related to the low-energy relativistic electrons detected in interplanetary space with the satellites IMP-I, IMP-II, and IMP-III:1. The first observations of 3–12-MeV solar-flare electrons in interplanetary space are presented. The solar electrons detected have kinetic energies nearly two orders of magnitude higher than any previously studied; thus, although flare events with a detectable flux of such particles occur relatively rarely, their study provides a new parameter in solar physics. The 7 July and 14 September 1966 events are outlined in detail, having the greatest relativistic electron to medium-energy proton ratios of the events detected before 1967. These events contrast with the 28 August 1966 event, which was intense in nucleons but contained no detectable component of relativistic electrons. The electron time histories are shown to have delayed onsets, and to be similar in form to those of high-energy protons, and the energy spectra and other features are described.2. Progress in the study of the solar modulation of interplanetary 3–12-MeV electrons is reviewed. Characteristics of the electron-intensity time variations during parts of 1963–67 are outlined; they are shown to be consistent with the hypothesis of the primary cosmic-ray nature of these particles and with a strong dependence on the local field conditions.
Cosmic-ray solar-flare increase of 28 January 1967
Authors: Mathews T. , Wilson B. G.
Published: April 2011

The main features of the solar-flare increase in cosmic-ray intensity observed on 28 January 1967 are presented. The flare increase showed no marked anisotropy. It is shown that the onset and decay of this increase can be well accounted for by anisotropic diffusion of particles in a spherically symmetric, inhomogeneous medium with a perfectly absorbing boundary at about 1.3 AU from the sun.
Production of neutrons and gamma rays by nuclear interactions in solar flares
Authors: Ito K. , Okazoe H. , Yoshimori M.
Published: April 2011

In recent years, the possibility has been discussed by various authors that solar neutrons and 2.2-MeV gamma rays are produced by the nuclear interactions of flare-accelerated particles with solar material. In this paper, it is emphasized that the ratio of neutrons to 2.2-MeV gamma rays depends significantly on the direction of motion of the flare-accelerated particles with respect to the solar atmosphere. For the direction of motion of flare-accelerated particles, we shall consider three cases: (a) isotropic motion, (b) upward-directed motion towards the corona, (c) downward-directed motion towards the photosphere. These flare-accelerated particles would interact with the solar atmosphere to produce neutrons with energies above several MeV. Some of the neutrons will escape into space through the corona, while some will be slowed down in the denser atmosphere and captured by the atmospheric protons with the emission of 2.2-MeV gamma rays.According to the calculations in this paper, the ratio of neutrons to 2.2-MeV gamma rays for case (b) is 10–20 times that for (a) or (c). The value for case (c) is twice that for case (a). For the expected solar neutron intensity, the values for (b) and (c) are ~10−6 and 4 × 10−2 of that for (a), respectively.
The enhanced daily variation in cosmic-ray intensity
Authors: Venkatesan D. , Mathews T.
Published: April 2011

The study of the super neutron monitor data from Calgary and Sulphur Mountain during January 1964 to May 1967 shows the importance of transient changes of intensity occurring over a few hours and its contribution to the daily variation. Trains of enhanced daily variation lasting a few days occur during recovery periods of fast Forbush and gradual decreases. The diurnal hour of maximum for a total of 250 days of enhanced daily variation during the period occurs at 17–18 h LT, which is the same as that for the rest of the period. The semidiurnal hour of maximum is distributed reasonably well over all hours, which points to its origin from transient changes in intensity.
Daily variation of cosmic rays during quiet and disturbed periods in 1965 and 1966
Authors: Tanskanen Pekka J.
Published: April 2011

Data from super neutron monitors at Deep River, Churchill, Resolute, and Alert have been used to study the daily variation of cosmic-ray intensity during 1965 and 1966. Intensities have been examined on a daily, weekly, and monthly basis as a function of the asymptotic direction of vertically incident 7.5-BeV particles. The data have been analyzed in an earth-centered solar-ecliptic coordinate system in which daily (due to the earth's rotation) and seasonal (due to the inclination of the earth's axis to the ecliptic plane) variations of the asymptotic directions are considered.During undisturbed periods the daily variation has been examined by applying a digital filter to the pressure-corrected data and also to the data after subtraction of a variable-amplitude Parker–Axford theoretical diurnal variation. Particular attention has been paid to the dependence of the observed daily variation on the solar-ecliptic latitude of the asymptotic direction.Seventy-three percent of the weeks considered in 1965 and 1966 give the phase of the first harmonic in a direction 85° ± 35 °E. Sixty percent of the weekly periods show a daily variation as a function of solar-ecliptic latitude which is in agreement with the Parker–Axford "streaming-velocity" theory. During Forbush decreases the diurnal phase shifts towards earlier hours and the amplitude increases to two to three times the predecrease level.
On the possibility of a two-way solar anisotropy producing the cosmic-ray diurnal variation
Authors: Kodama M. , Nagashima K.
Published: April 2011

Two pieces of experimental evidence, which are inconsistent with the hypothesis of a one-way solar anisotropy as an interpretation of the cosmic-ray diurnal variation, are presented. The diurnal variation of the temperature-corrected meson component at Deep River was examined and compared with that of the neutron component. Both diurnal variations were averaged for each solar rotation from No. 1762 to No. 1787. If a one-way solar anisotropy is assumed, the time of maximum for neutrons should be about half an hour earlier than that for mesons at Deep River. However, the observations show that the phase difference between the two components is the reverse of that expected. Further evidence is obtained from a comparison of the diurnal variation on Mt. Norikura (2 770 m, 11.4 GeV) to that in Itabashi (20 m, 11.5 GeV). According to theoretical calculations based on a one-way solar anisotropy, the time of maximum at high altitude is earlier than or equal to that at sea level, but observations obtained during Dec. 1966 to Mar. 1967 suggest that the opposite is true.
Two anisotropies of the cosmic-ray particles producing the cosmic-ray diurnal variation
Authors: Kitamura Masatoshi
Published: April 2011

The solar diurnal variations of both meson and nucleon components of cosmic rays at sea level at geomagnetic latitude 57.5° and geomagnetic longitude 0° are analyzed by the model in which two anisotropies of cosmic-ray particles (one of them, Δj1, from about 20 h L.T. and the other, Δj2, from about 8 h L.T. in interplanetary space) produce the solar diurnal variation of the cosmic-ray intensity on the earth.When the energy spectra of Δj1 and Δj2 are represented by [Formula: see text] and [Formula: see text], respectively, where j0(E) is the normal energy spectrum of the primary cosmic rays, it is shown that the evaluation for m1 = 1, 2, m2 = 0 and the cutoffs at 8 and 10 BeV on the low-energy side of spectra of both Δj1 and Δj2 agree well with the observational results at Deep River.
Cosmic-ray anisotropy in the north–south direction
Authors: Murakami K. , Kudo S.
Published: April 2011

For the study of a cosmic-ray anisotropy in the north–south direction, the day-to-day variation of the difference (N–S) of cosmic-ray neutron intensities between the arctic and the antarctic was examined with respect to solar rotations. Harmonic analysis on the variation of the intensity difference shows the existence of a recurrent variation with half the period of a solar rotation. Such a recurrent variation is closely connected with the rapid phase changes of the cosmic-ray diurnal variation during a solar rotation. Regarding the sectored structure of solar wind reported by Wilcox and Ness, the intensity difference (N–S) increases when the earth is passing near a boundary from the (+) sector into the (−) sector, while it decreases near the other boundary. This N–S anisotropy of cosmic rays seems to be caused by the transitional change of cosmic-ray trajectories near the sector boundary and by the spatial distribution of cosmic-ray flux.
The solar semidiurnal variation of cosmic-ray intensity 70 m.w.e. underground
Authors: Cini-Castagnoli G. , Dodero M. A. , Andreis L.
Published: April 2011

Cosmic-ray intensity measurements have been carried out during the last year at a depth of 70 m.w.e. in the Monte dei Cappuccini laboratory in Torino, using solid vertical semicubical scintillator telescopes with a total area of 2 m2. Hourly data for 245 days corrected for barometric changes have been analyzed for the solar, apparent sidereal, and antisidereal daily variations whose harmonics are as follows:[Formula: see text]The true sidereal diurnal variation is estimated to have an amplitude of 0.019% with a time of maximum at 1720 h local sidereal time. The solar diurnal variation at different depths underground follows the energy dependence calculated with Axford's theory. The solar semidiurnal variation shows instead a fairly constant value at different μ energies. Its order of magnitude agrees with that expected as a result of Fermi acceleration in collisions of primaries moving in roughly solar and antisolar directions with solar wind inhomogeneities.
Morphology of the March 23, 1966, Forbush decrease
Authors: Mercer J. B. , Wilson B. G.
Published: April 2011

A three-dimensional analysis of anisotropies occurring in a major Forbush decrease is presented. The onset of the decrease is first detected at the earth from a direction 90° east of the sun–earth line.
Anisotropy in cosmic-ray intensity associated with Forbush decreases
Authors: Mathews T. , Mercer J. B. , Venkatesan D.
Published: April 2011

A study of the Forbush decrease of 23 September 1966 shows that the predecrease anisotropy developed from a direction 85° to the west of the sun–earth line. The rate of development of the anisotropy suggests that the "turbulent" plasma producing the Forbush decrease occupied a volume of diameter ≈0.2–0.3 AU. If the plasma clouds away from the earth produced the anisotropy at the earth, then it is reasonable to attribute a part of the highly variable daily variation in cosmic-ray intensity to such distant scattering centers.
Methods for the analysis of Forbush decreases and cosmic-ray phenomena accompanying their onset and development
Authors: Sandström Arne Eld
Published: April 2011

The variations of the worldwide intensity level before and during a Forbush decrease are established by means of a modification of the well-known method introduced by Sekido. By application of proper weights to their records any number of stations, inside a given rigidity region, can be employed to establish the worldwide intensity-level curve. The daily variation is given by the differences between the latter and the records from individual stations. Several methods are available to determine the phase and amplitude and their variations during the onset and development of Forbush decreases. Three of these methods are discussed, viz.: harmonic analysis for single days and individual records, applicable in cases of a very enhanced diurnal variation; harmonic analysis of superimposed records; and the analysis of the intensity distribution around the world during bihourly periods.
Variations in cosmic-ray spectra during Forbush events in 1966
Authors: Wolfson C. J. , Newkirk L. L. , Nobles R. A. , Reynolds G. T. , Walt M.
Published: April 2011

Measurements of cosmic-ray spectra, using the neutron multiplicity technique, were made during 1966 at White Mountain, California. Multiplicity spectra observed during Forbush events beginning on March 23 and August 30, 1966 demonstrated that the modulation mechanism most strongly affected the low-multiplicity (i.e. low-energy) rates. The decreases were about 5.5% and 7.0% in the multiplicity m = 1 rates, gradually diminished with increasing m, and were unobservable around m = 50. During the August 30 Forbush event, intensity increases of a few hours' duration occurred. The increase, which began on September 3 at 1800 U.T. and occurred simultaneously with the largest magnetic storm of the year, exhibited a preferential increase in the low-multiplicity rates. The recovery effect decreased with increasing multiplicity and essentially disappeared at m = 10. The second largest magnetic storm of 1966 occurred on March 14 and again a significant intensity increase was observed at White Mountain. It also displayed a preferential increase in the low-multiplicity rates. A brief discussion, with reference to the storm time increases previously observed on September 13, 1957 and February 11, 1958, of possible modulation mechanisms responsible for these increases is presented.
Solar modulation of galactic cosmic rays near solar minimum (1965)
Authors: Balasubrahmanyan V. K. , Hagge D. E. , McDonald F. B.
Published: April 2011

The results of the continuous monitoring of the intensity of cosmic rays (of energy > 50 MeV) with identical G-M counter telescopes flown in satellites IMP I, II, and III and OGO-I are presented along with the differential spectrum studies obtained from balloon flights at Fort Churchill and from satellites. A comparison of the time behavior of the G-M counter data with Deep River neutron monitor data suggests the presence of a "hysteresis" type of behavior due to spectral changes occurring near solar minimum. The existence of this "hysteresis" suggests that the radial gradient of cosmic rays near the earth could be much smaller than the ~ 10%/AU obtained by O'Gallagher and Simpson (1967) and O'Gallagher (1967) at higher energies. The long-term intensity variation of cosmic rays seems to follow the Ap index rather closely in phase, in contrast to sunspot numbers which display a pronounced phase difference with cosmic-ray intensity. The differential spectra of protons and He nuclei have been analyzed in terms of two different models for the propagation in the interplanetary medium. The modulations indicated by the present data seem to disagree with a diffusion coefficient proportional to βR where β and R are the velocity and rigidity of the particle respectively (Jokipii 1966).
The primary cosmic-ray electron spectrum in the energy range from 300 MeV to 4 BeV from 1964 to 1966
Authors: L'heureux Jacques , Meyer Peter
Published: April 2011

Measurements of the primary electron spectrum were made during the summers of 1964, 1965, and 1966 using a balloon-borne counter telescope flown from Fort Churchill, Manitoba. Several balloon flights were carried out in each year in order to eliminate short-term intensity variations. This paper addresses itself to two questions: (1) the determination of the energy spectrum of primary electrons in the energy interval from 300 MeV to 4 BeV; and (2) the long-term intensity variations of the primary electron flux from 1964 through 1966. The energy spectrum was determined with improved accuracy in 1966 and agrees with our previous results. Comparison of the electron spectra obtained in 1964, 1965, and 1966 shows that, within the errors of our measurements, no long-term intensity variation existed. The upper limit for the change of flux with respect to 1965 amounts to 20% in all energy intervals studied.[Formula: see text]
Primary protons and alpha particles in the energy range 70–240 MeV/nucleon observed during 1966
Authors: Badhwar G. D. , Deney C. L. , Dennis B. R. , Kaplon M. F.
Published: April 2011

The differential energy spectra of cosmic-ray protons and helium nuclei were measured on two balloon flights from Fort Churchill, Canada, during late July and early August of 1966. The measurements were made using a double dE/dx vs. E detector with an energy-independent (for stopping particles) acceptance aperture of 6 cm2 sr. The detector floated for a total of 25 hours under 2.7 g/cm2 of residual material. The acceptance range of energies is 70–240 MeV/nucleon for protons and 4He. Both the proton and 4He differential spectra are depressed from solar minimum and appear similar to 1963 results. The P/He ratio over the energy range is 4.3 ± 1. The spectra are compared to those obtained in 1965. It is found that the modulation function is proportional to either R or Rβ.
The long-term variation of the cosmic radiation
Authors: Lockwood J. A. , Webber W. R.
Published: April 2011

The variation in the cosmic-ray intensity recorded by neutron monitors from 1958 to 1965 has been investigated to deduce the form of the solar modulation of the cosmic radiation. The observed changes in the intensity at the neutron monitor stations, averaged over quarter-year periods, were compared with changes calculated using modulation functions depending upon energy, rigidity, and velocity × rigidity. These calculations were based upon the revised differential response functions deduced by Lockwood and Webber (1967). The variance between the observed and calculated changes in the neutron monitor intensities at different stations was minimized to determine the best form of the solar modulation function. We find that the change of the primary cosmic radiation, deduced from the change in the neutron monitor intensity as well as from direct measurements of the primary flux, can be described by a modulation of the form exp(–K/P) in the rigidity range 0.5 < P < 50 GV. The change between 1959 and 1965 can be fitted with K = 1.94 ± 0.09 and between 1963 and 1965 with K = 0.36 ± 0.05.
Rigidity spectra of primary cosmic radiation
Authors: Kasturirangan K. , Nerurkar N. W.
Published: April 2011

The comparison of the cosmic-ray intensity measured with balloon-borne ion chambers at different atmospheric depths at stations in North America and in the U.S.S.R. for the period 1937–67 is presented. It is found that there is no difference in variations of cosmic-ray spectra in periods of increasing and decreasing solar activity in 1954–64. In 1937–40 the cosmic-ray spectra are found to be distinctly different, suggesting a slow change in the spectrum over periods greater than the 11-year cycle of solar activity.
The solar radial gradient of galactic cosmic rays
Authors: Gleeson L. J. , Axford W. I.
Published: April 2011

The radial gradient of cosmic rays in the interplanetary region has been investigated taking into account convection, diffusion, energy losses, and differential streaming S. At high energies the analysis given here shows that S can be neglected and the radial gradient written C(r, T)Gs(r, T), where Gs(r, T) is the gradient given by the convection–diffusion theory and C(r, T) is an energy-dependent correction factor which can be computed from the observed differential intensity spectrum. During 1964–65 this result can probably be used for protons and helium nuclei down to a few hundred MeV/nucleon, with, at that time, [Formula: see text]. At lower energies Gs will be quite inaccurate as an estimate of the radial gradient unless changes in C are offset by streaming. Combining observations with this analysis it is shown that the radial anisotropy of protons (ξ) is: (i) positive but small (< 0.02%) at kinetic energies [Formula: see text]; (ii) negative in the range 40–600 MeV with ξmax = −0.75% (which should be observable); (iii) positive for energies less than about 40 MeV.
Implications of the cosmic-ray radial intensity gradients observed during minimum solar modulation
Authors: O'Gallagher J. J.
Published: April 2011

We have already reported the cosmic-ray radial intensity gradients for both protons and helium nuclei measured over two decades in Rβ (magnetic rigidity R times velocity β) on the Mariner IV space probe in 1965 which showed that the modulating function is separable into the product of a function of particle parameters and a function of the time t and the heliocentric radius r for the observations (O'Gallagher and Simpson 1967). The modulating function can be written as exp (−η(r, t)/ƒ(R, β)) where η(r, t) is the modulating parameter and ƒ(R, β) = Rβ for [Formula: see text] and ƒ(R, β) [Formula: see text] β for [Formula: see text]. The magnitude of the observed gradient corresponds to a change Δη = −0.2 ± 0.05 GV for Δr = 0.4 AU and at 1 GV yields a value for the diffusion coefficient in Parker's model of 3.2 × 1021 cm/s. If the value of η in 1965 is small [Formula: see text], the observed value of Δη/Δr implies that the greatest part of the modulation takes place within 5 AU at solar minimum. The value of Δη; derived from these gradient measurements is compared with estimates of the change in η required to produce the observed time–intensity variations during the solar cycle.
The solar-wind modulation of cosmic-ray intensity
Authors: Sreenivasan S. R. , Johnson R. H.
Published: April 2011

It is shown from a consideration of the diffusion of cosmic rays in interplanetary space that the convection of particles by the solar wind is an important effect and hence should be incorporated in all discussions of the propagation of cosmic rays. This provides a common basis for looking at the correlation between relative changes of solar-wind velocity and changes of cosmic-ray intensity. The correlation is shown to be negative and significant. The correlation coefficient is large for a Forbush event, indicating that convection plays a dominant role during the event as contrasted with the normal pattern of changes of cosmic-ray intensity. The 11-year variation of cosmic-ray intensities and the Forbush event receive a natural interpretation on the basis of this discussion.
Periodic cosmic-ray variations associated with the sector structure of the interplanetary magnetic field
Authors: Patel V. L. , Chasson R. L.
Published: April 2011

Observations by IMP-1 satellite have established that the interplanetary magnetic field is divided into sectors of opposing polarity. These observations have been confirmed by observations with IMP-2 and Mariner 4. The effect of this sector structure on the cosmic-ray intensity observed on the earth has been studied using daily averages of pressure-corrected neutron monitor data from several locations. These data have been analyzed using the method of superposition of epochs, beginning at the edge of the observed sector. The results indicate periodic variations of 6–8-day periods and 0.5 to 1.0% amplitude in cosmic-ray intensity, associated with the passage of positive and negative sectors moving past the earth, including a weak recurrence at 27 days. Theoretical implications of these observations are discussed.
The second spherical harmonic of the diurnal variation and the orientation of the interplanetary magnetic field
Authors: Skeipin G. V. , Krivoshapkin P. A. , Krymsky G. F. , Kuzmin A. I.
Published: April 2011

The super neutron monitor data from Goose Bay and Deep River for 1965 have been analyzed to give month-to-month changes of the first and second harmonics of the solar-diurnal variation. Using these results together with various suppositions about the nature of the cosmic-ray distribution vector, information is obtained concerning the orientation of the interplanetary magnetic field.
Gradient of galactic cosmic rays normal to the solar equatorial plane
Authors: Patel D. , Sababhai V. , Subramanian G.
Published: April 2011

Predictions concerning the anisotropy of galactic cosmic rays due to a gradient of cosmic-ray density perpendicular to the solar equatorial plane have been verified experimentally as follows. (1) The energy spectrum of the variation of the semidiurnal component has a positive exponent. (2) The diurnal and the semidiurnal components are oriented with respect to the interplanetary magnetic field. (3) A deficiency of cosmic-ray intensity, Tmin, is observed along the direction of the interplanetary magnetic field on days when the energy spectrum of the diurnal variation has an exponent different from zero.
Monte Carlo experiment to determine the statistical uncertainty for the average 24-hour wave derived from filtered and unfiltered data
Authors: Forbush Scott E. , Duggal S. P. , Pomerantz Martin A.
Published: April 2011

To test whether the diurnal variation is more reliably determined from filtered data, a daily harmonic analysis is made before and after filtering an adequate sequence of synthetic bihourly values containing only random noise and a 24-hour wave of constant phase and amplitude. For each of three filters it is shown, empirically, that the statistical uncertainty of the 24-hour wave from N days of such filtered data does not differ significantly from that from N days of unfiltered data. The filters were of different bandwidths and each was designed to pass the 24-hour wave.
Transport of cosmic rays in the interplanetary medium
Authors: Roelof Edmond C.
Published: April 2011

By quasi-linearization of the Liouville equation for a charged particle in an electromagnetic field combined with an ensemble average over field configurations, a transport equation is derived for the ensemble average particle distribution function. The resulting integrodifferential equation is rewritten in terms of a simpler characteristic function which, when found, gives the complete solution in terms of the particle orbits in the ensemble mean fields. With the appropriate approximations, the equation reduces to the Fokker–Planck form applied recently by Jokipii to galactic cosmic-ray modulation, and by the author to energetic solar-flare particle propagation. It is argued that the equation, although complicated, offers several advantages as a starting point for transport theory over the simpler, but less appropriate, Fokker–Planck and Boltzmann equations.
A comparison of the characteristics of corotating and flare-initiated Forbush decreases
Authors: Bukata R. P. , McCracken K. G. , Rao U. R.
Published: April 2011

Data acquired by the deep space probes Pioneer VI and Pioneer VII which differ by [Formula: see text] in heliographic longitude are presented to illustrate the basic similarities and differences between the classes of Forbush decrease resulting from corotating shock fronts and radially propagating blast waves. An example is presented to establish directly the existence of the corotating Forbush decrease, and from the intensity–time profile of the event it is concluded that the detailed time structure of the Forbush decrease is invariant over a time scale of about 4 days. An example of the Forbush decrease resulting from a solar-induced blast wave is also presented wherein an azimuthal gradient of about a factor of 4 per 60° of azimuth is observed.
Variation of the anisotropy of the cosmic radiation within the sector structure of the interplanetary magnetic field
Authors: Ryder P. , Hatton C. J.
Published: April 2011

In a study of the diurnal-type variation, a wide-band filter has been applied to the pressure-corrected intensity recorded by the Deep River neutron monitor. The period December 1963 to February 1964 has been chosen for the analysis because IMP 1 provided information on the sector structure of the interplanetary field at this time.A superimposed epoch analysis of the filtered time series shows that there is a systematic change in the observed anisotropy through the sectors. If it is assumed that the variation is independent of energy across a sector, then the change can be explained by a streaming of the cosmic radiation away from the sun at the leading edge and towards it at the trailing edge. This interpretation is consistent with the observed distribution of field strength and solar wind velocity.
Attenuation of neutron monitor radiation in the atmosphere
Authors: Carmichael H. , Bercovitch M. , Shea M. A. , Magidin M. , Peterson R. W.
Published: April 2011

An NM-64 neutron monitor latitude survey made by road transport in the summer of 1965 in Canada, the United States, and Mexico was extended, in the summer of 1966, to the western seaboard of the United States and Hawaii. In 1966 in the vicinity of Mt. Hood (2.43 GV), Palomar Mt. (5.71 GV), and Mt. Haleakela (13.3 GV) advantage was taken of the possibility of changing altitude without significant change of geomagnetic cutoff. At each of these places also a smaller lead polyethylene neutron monitor was flown at seven different pressure altitudes between 530 mm Hg and 140 mm Hg. The airborne monitor was calibrated in terms of the NM-64 when the transport van was at 10 000 ft on the summit of Haleakela. It was found that graphical smoothing of vertical trajectory cutoffs in latitude and longitude eliminated an unnatural kink in the latitude curve near Mexico City. The 1965 and 1966 rates were adjusted to May 12–13, 1965, the date of the IQSY maximum, using data from a fixed monitor and allowing for the dependence of the secular fluctuations on cutoff and altitude. The attenuation coefficient throughout the atmosphere was determined from the data and also a new specific attenuation coefficient which is a function only of rigidity of the primary flux and depth in the atmosphere. The specific attenuation coefficient has a comparatively high value consistent with that observed for solar proton events.
Measurements of cosmic-ray electrons in the energy range 4 MeV to 6 BeV at 2 g/cm2 atmospheric depth at Ft. Churchill
Authors: Beedle R. E. , Webber W. R.
Published: April 2011

In this paper we extend our recent measurements on electrons in the energy range 70–2 400 MeV to energies from 4 MeV to 6 000 MeV. These new measurements have been made using two separate telescopes which are sensitive to electrons in different but overlapping energy ranges. Detailed ascent curves are available for electrons from 4 MeV to [Formula: see text], permitting the derivation of a secondary electron production function at the top of the atmosphere. This production function is compared with the theoretical calculations of Perola and Scarsi (1966) and Verma (1967) appropriate to energies >50 MeV and the calculations of Beedle (1966) relating to the production of low-energy electrons by the knock-on process and by Compton scattering of photons.From our studies we derive the total electron spectrum existing at 2.3 g/cm2 atmospheric depth at Ft. Churchill in 1966. Subtracting from this our experimentally derived secondary production of electrons, we are able to determine the spectrum of extraterrestrial electrons from [Formula: see text] to >6 BeV. This spectrum is compared with other observations, and the galactic nature of the particles is discussed. The variability of these particles with time is investigated. Some observations regarding the creation of these electrons in the galaxy are also made.
Albedo neutrons of the earth's atmosphere and their distribution in space near the earth
Authors: Sokolov V. D. , Salimzibaeov R. B. , Shafer Yu. G.
Published: April 2011

During 1960–62 at Yakutsk measurements were made with balloons for the determination of the albedo neutron flux in the earth's atmosphere. The neutrons were detected by counters filled with BF3. The measurements were used to determine the altitudinal distribution of neutrons with the cadmium cutoff energy and from thermal energies up to 105 eV. The corresponding fluxes at the boundary of the atmosphere were found to be 0.035 neutron cm−2 s −1 and 0.48–0.58 neutron cm−2 s −1 by extrapolation of measurements in the atmosphere. The total albedo neutron flux throughout the spectrum is 1.2–1.4 neutron cm−2 s−1. The calculated distribution of the flux of slow albedo neutrons and the density of their decay were obtained in space near the earth up to about 60 000 km.
A study of atmospheric neutrons by the resonance detector method
Authors: Efimov Yu. E. , Romanov A. M.
Published: April 2011

The possibilities and the conditions of using resonance detectors for investigation of slow neutrons in the atmosphere are discussed. The epithermal neutron fluxes from the lower hemisphere were measured by means of the indium foil activation method in June 1966 at the geomagnetic latitude 47°. Assuming the epithermal atmospheric neutron spectrum to be Φ(E) = Φ0/E and expressing the neutron energy in eV, we obtain the following values of Φ0 (neutron cm−2 s−1) from our measurements: 0.078 ± 0.019 (at a depth x = 40 g cm−2), 0.049 ± 0.015 (x = 22 g cm−2), 0.023 ± 0.010 (x = 8 g cm−2). It is pointed out that resonance detectors can be used to study the spectra of epithermal neutrons in nonequilibrium atmospheric layers.
Time changes of the attenuation coefficients for cosmic-ray neutron monitors
Authors: Bachelet F. , Dyring E. , Iucci N. , Villoresi G.
Published: April 2011

The time variation of the attenuation coefficients is synoptically studied by regression analysis on reduced and filtered daily data of 21 IGY neutron monitors from 1957 to 1965 and 11 IQSY supermonitors from 1964 to 1966. For the sea-level IGY monitors at high latitude a typical peak-to-peak amplitude of 4% is found for the solar-cycle change, in agreement with an independent estimate of the effect. The supermonitor results show, as expected, no relevant time variation in the period studied and smaller differences than the IGY monitors among stations of similar geophysical conditions.Attenuation coefficients obtained by mobile monitor measurements in 1967 are also presented.
The intensity variations of selected multiplicities in the Leeds NM64 neutron monitor
Authors: Griffiths W. K. , Harman C. V. , Hatton C. J. , Marsden P. L. , Ryder P.
Published: April 2011

A study of the multiplicity variations in an NM64 monitor is being made at Leeds, where detected multiplicities of m = 1, [Formula: see text], and [Formula: see text] are recorded. The present paper is a preliminary report on this work and includes a discussion of the barometric coefficients associated with these multiplicities and the variations of intensity observed during some recent Forbush decreases.
Calculated specific yield functions for neutron monitors
Authors: Wainio K. M. , Colvin T. H. , More K. A. , Tiffany O. L.
Published: April 2011

Results of calculations to determine specific yield functions for IGY neutron monitors are reported for vertically incident cosmic-ray protons in the range of 1 < Pc < 6 GV. The Monte Carlo method is used to calculate secondary nucleon-flux intensities at atmospheric depths of 312, 680, and 1 000 g/cm2. Experimental data on neutron monitor response are employed to relate the calculated flux data to count rates, and hence to specific yields, at the corresponding depths. Comparison with empirical data for the specific yield function at sea level shows fair agreement for rigidities less than 3 GV, but calculated yields are considerably smaller than the empirical data at higher rigidities. Various possible explanations for the discrepancy are discussed. At this time, the most probable cause appears to be the assumption that vertically incident cosmic rays produce most of the counts registered by neutron monitors.
Critique of successive differencing method of regression analysis
Authors: Iona Mario , Wiskerchen Michael
Published: April 2011

Various regression techniques have been proposed to calculate barometric coefficients from time-varying cosmic rays recorded by neutron monitors. One of these, the successive differencing method, was carefully examined by applying the technique to simulated time-dependent and time-independent cosmic-ray data and also by investigating the mathematical foundations of the technique. When applying the successive differencing method to time-independent data, the slope and slope error values were found to be dependent on the order in which the data appeared. By ordering the data from highest to lowest pressure, the slope error increased markedly. This falsification of the slope can be shown to be due to improper weighting of the differenced data. Calculations have also been performed to show that the successive differencing method, when applied to intensities containing a linear time dependence, produces a regression slope which retains a time dependence proportional to the difference between the first and last pressure values. The falsification of the slope due to improper weighting of the differenced data can be very much larger than the maximum effect of any reasonable time variation of the nucleonic component.
Direct measurements of geomagnetic cutoffs for cosmic-ray particles in the latitude range 45° to 70° using balloons and satellites
Authors: Bingham R. G. , Sawyer D. M. , Ormes J. F. , Webber W. R.
Published: April 2011

The quiet-time cutoff rigidities for cosmic-ray particles have been measured directly in 1963–65 at six locations in North America with geomagnetic latitudes (λ) between 45° and 70° using balloon-borne Cerenkov-scintillation counters. An identical counter with 0.1 of the area has been carried aloft in a polar-orbiting satellite from which it has been possible to determine the cutoffs for protons in four intervals between L = 3 and L = 5. The measured cutoffs are consistently below those expected on the basis of detailed orbit calculations based on the surface field of the earth (Shea and Smart 1967). These differences amount to a [Formula: see text] reduction at λ = 45°, increasing to [Formula: see text] at 60°. At 70° the cutoff is apparently <12% of the expected internal field value at 190 MV at 2100 hours local time.A limit to the amount of reduction produced by a ring current within the magnetosphere can be set from the data at latitudes <60°. The most reasonable value for the magnetic moment of this ring current is 0.08 Me. The situation at latitudes >60° is characterized by large diurnal changes in the cutoffs.
Latitude survey of neutron multiplicity using a shipborne NM-64 neutron monitor
Authors: Kodama M. , Ohuchi T.
Published: April 2011

The latitude dependence of the neutron multiplicity effect has been measured using a 3-NM-64 neutron monitor along the route Japan–Australia–Antarctic–South Africa–Ceylon–Japan between December 1966 and April 1967. Throughout the whole voyage, events whose multiplicities were in the range 1 to 6 and more were recorded. A preliminary report of the threshold-rigidity dependence of events of various multiplicities is presented, based on data from the outward voyage. The gradient of the rigidity dependence is found to be steepest for events of multiplicity 2, while that for multiplicity 1 is almost the same as that for multiplicity 3. The mean multiplicity of events recorded by the present shipborne neutron monitor varies linearly from 1.418 to 1.445 in the rigidity interval 0.1–17 GV.
Changes in magnetopause positions and cosmic-ray intensity
Authors: Patel V. L. , Chasson R. L.
Published: April 2011

Magnetic field and solar plasma experiments on satellites have shown that the position of the magnetopause (magnetospheric boundary) is variable. During a magnetic storm it may move as close as 8 geocentric earth radii. Even during quiet geomagnetic activity it may change as much as 2 earth radii. The Explorer 12 magnetic field experiment allows continuous observation of the magnetopause position twice a day for the period of August–December 1961. We have studied the changes in cosmic-ray intensity associated with such motion of the magnetopause using neutron monitor data from several ground observatories. The method of superposition of epochs shows a definite relationship, viz. inward motion of the magnetopause is associated with a decrease and outward motion with an increase in the cosmic-ray intensity. However, this relationship becomes weak after 20 days from the decrease in the magnetopause distances, i.e. increase in the energy density of the solar plasma responsible for such changes. The effect of the plasma density increase corresponds to the passage of the sector boundary of the interplanetary field.
Remark on the energy determination of high-energy nucleons by means of the absorption calorimeter
Authors: Somogyi A. , Válas G. , Varga A.
Published: April 2011

The sources of error in energy determinations carried out by means of an ionization calorimeter are well known as are the values of the relevant corrections. Very little if anything is known, however, of the statistical uncertainties of these corrections. An analytical method has been worked out in order to determine the probability that a certain fraction of the primary energy leaves a calorimeter of a given thickness and thus escapes detection. The method makes due allowance for the fluctuation of the inelasticity coefficient. Numerical calculations have been carried out assuming various forms for the probability distribution function of the inelasticity coefficient, and the results of the calculations are given for various calorimeter thicknesses.
Large-area proportional counter
Authors: Higashi S. , Kitamuea T. , Miono S. , Nakagawa M. , Ozaki S. , Takahashi T. , Watase Y.
Published: April 2011

The properties of proportional counters have been studied using a model of size 2 × 2 m2 and 10 cm deep filled with PR gas at atmospheric pressure. These counters were found to be useful for constructing large-scale detectors with uniform sensitivity over large areas, such as 2 × 2 m2 or more.
A cosmic-ray counter telescope for high mass resolution
Authors: Badhwar G. D. , Deney C. L. , Dennis B. R. , Kaplon M. F.
Published: April 2011

A dE/dx by E counter telescope consisting of two ¼-in.-thick plastic scintillators as the dE/dx elements and a 5-in.-deep NaI(Tl) crystal as the E element is described. The geometrical factor of the system is 6 cm2 sr and is energy independent for stopping particles. The calibration of the detector and its response to sea-level muons and the low-energy nuclei of cosmic radiation are presented. The expected mass resolution is compared to that observed, and they are found to be in excellent agreement. Protons, deuterons, 3He, 4He, and heavier nuclei are all resolved over the energy range corresponding to the crystal thickness. Information on the nonlinear behavior of the light output from the plastic scintillator NE102 as a function of ionization loss is presented.
The installation for the study of nuclear interactions at 1012–1013 eV
Authors: Abdullaev A. M. , Azimov S. A. , Zaynutdinov H. , Mulladzhanov E. , Yuldashbaev T. S.
Published: April 2011

A description is given of the installation which was constructed at an altitude of 3 200 m for the study of nuclear interactions at energies of 1012–1013 eV. The apparatus, which has an effective area of 10 m2, includes an ionization calorimeter and a Cerenkov total absorption spectrometer for the measurement of the energies of the primary particles, a μ-meson detector consisting of Cerenkov counters and spark chambers, and also a spark chamber for the study of the angular distribution of secondary particles.
The use of solid iron magnets in the study of nuclear-active particles
Authors: Bull R. M. , Nash W. F. , Haywood J. K.
Published: April 2011

Solid iron magnets have found increasing use in experiments requiring momentum measurements on high-energy μ mesons. Such magnets enable high fields to be produced over very large volumes at very low cost and are consequently particularly attractive for cosmic-ray studies. They have not been used, however, for measurements on particles exhibiting strong interactions. This paper describes the possibilities of using multiple solid iron magnets for this purpose and analyzes some of their characteristics.
Influence of the electron lateral spread in the air slit on energy measurements in emulsion chambers
Authors: Baradzei L. T. , Kanevskaya E. A. , Smokodin Yu. A.
Published: April 2011

The effect of a decrease in the electron density near the cascade axis when a cascade passes through the gap between the lead filter and the emulsion of an emulsion chamber has been studied experimentally. This involved the measurement of the optical densities in circles of 48, 58, 84, and 140 μ radius in three X-ray films arranged 400, 800, and 1 200 μ from the surface of a filter whose thickness was 6 cascade units. The optical densities were measured for the spots caused by the electron–photon cascades with energies of 1–2 TeV, 2–7 TeV, and more than 7 TeV. The results show that the presence of a gap between the filter and the photoemulsion results in an underestimation of the measured energy by several tens of percent.
Image-intensifier photography of simulated showers in large-area layers of plastic scintillator
Authors: Huggett R. W. , Sandor T. , Webb J. E.
Published: April 2011

Preliminary results are presented of some tests which have been made to determine the feasibility of using an image-intensifier camera to photograph showers developing within an ionization calorimeter containing large sheets of plastic scintillator. The camera utilizes an EMI 9694B image intensifier, a four-stage cascade type with magnetic focusing. The first three stages of the intensifier are operated with a steady voltage and the last stage is pulsed. In the tests the camera is used to view the shorter edge of a sheet of Pilot Y plastic scintillator 91.5 cm × 183 cm and 2.5 cm thick. Showers of various sizes occurring within the scintillator are simulated by a nanosecond light source of appropriate size inserted into holes in the scintillator. The intensity of the source is calibrated using a photomultiplier to compare the light output of the source with that from single muons traversing the scintillator. All the tests were made with the source near the lens axis. The tests show that with the optical system anticipated to be used in the final application the threshold for shower detection seems to be sufficiently low and the image size sufficiently small to enable the system to be used over the required depth of field to obtain space and energy resolution of showers that occur simultaneously within the calorimeter with energies around 10 TeV.
Arrangement for measuring the momentum spectrum and the charge ratio of the high-energy cosmic-ray muon horizontal flux
Authors: Alchudjian S. V. , Asatiani T. L. , Badalian H. V. , Gazarian K. A. , Mekilov G. I. , Krishchian M. V. , Prokhorov A. N. , Prokhorov V. N.
Published: April 2011

The magnetic spectrometer of the wire spark chambers with memory of ferrite cores designed for the measurement of the momentum spectrum of high-energy muons (p ~ 3 × 103 GeV/c) at large zenith angles is described. Some characteristics of the wire spark chambers of large dimensions (S ~ 1 m2) are given. The magnetic deflections of the charged particles are automatically calculated and printed by means of a special calculating device. The ferrite memories of the wire spark chambers were directly used as "memory of the device".
A Nuclear Spin Relaxation Study of the Spin–Rotation Interaction in Symmetric Top Molecules
Authors: Armstrong Robin L. , Courtney James A.
Published: April 2011

The spin–lattice relaxation times T1 of 1H, 19F, and 31P nuclei were measured in gaseous samples of BF3, CHF3, CH3F, PH3, and NH3 at room temperature for densities from 0.03 to 10 amagat. In several cases the behavior of T1 at the lowest densities snowed deviations from the linear variation characteristic of the extreme narrowing region. 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. The results obtained are compared with those available from other types of experiments. This comparison indicates that the theory for spin–lattice relaxation in dilute gases of symmetric top molecules needs to be carefully reassessed.