Cosmic Measurements Research Articles

Low-energy cosmic X-ray measurements

An experiment is described to investigate cosmic X rays in the energy range 0.25–12 keV. The data-recovery system and methods of spectral analysis are considered. Results are presented for the energy spectrum of the diffuse X-ray component and its distribution over the northern sky down to 1.6 keV with a limited extension at 0.27 keV.In the energy range 1.6 to 12 keV, the spectrum is represented by:[Formula: see text]although separate analyses indicate a flattening below 4.5 keV to give:[Formula: see text]and[Formula: see text]At the lowest energies, the flux appears to increase more rapidly and exhibits some anisotropy in arrival directions related to the gross galactic structure. Spectral characteristics of the Crab Nebula and Cygnus X-2 have also been determined.

Cosmic X-ray measurements at Resolute

An upper limit of 6.9 ± 2.1 photons/cm2 sr s in the range 2–10 Å is reported for the X-ray flux above the polar atmosphere.

The Solar Helium Abundance.

Possible sources of the discrepancy between determinations of the solar helium abundance by means of theoretical models and solar cosmic particle measurements are discussed. (C.E.S.)

A selection rule for the production of pions in the steady-state theory

BS>The process of continuous production of mesons ( pi ) and nucleons that is characteristic of the steady-state theory is considered. By making reasonable assumptions on the energy distributions of the particles when created the flux at each point in space and on earth can be calculated. It is found statistically that meson ( pi ) production is extremely predominant over nucleon production, which cortradicts experimental cosmic nucleon flux measurements. A selective rule is imposed that prohibits the production of mesons ( pi ) to compensate the difference in experimental and statistical results. (C.E.S.)

Intensities of muons underground at large zenith angles

Experimental results are reported for an underground cosmic ray telescope measurement of the absolute muon intensity at zenith angle 69°±3° near sea level. Muons detected by the apparatus were incident normally on a steep, smooth bluff at ground level and traveled through large thicknesses ofrock on trajectories at 69°. The telescope was situated on the horizontal floor of an underground limestone quarry at various distances behind the bluff. Measured intensities in units s−1 cm−2 sr−1 at oblique depths from the bluff are: (4.48±0.32)·10−4 at 38.3 m w.e.; (1.66±0.13)·10−4 at 112 m w.e.; (4.94±0.37)·10−5 at 255 m w.e.; and (2.92±0.22)·10−5 at 354 m w.e. A curve through these data crosses the corresponding vertical intensity curve at a depth near 140 m w.e., beyond which the 69° intensity always exceeds the vertical intensity. Interpretation of this and other aspects of the results is based on the diffusion equation for high-energy pions in the atmosphere. The results are in general agreement with recent magnetic spectrometer work.

Cosmic Noise Measurements from 1960 η1 at 3.8 Mc./s.

WE wish to report the results of an experiment to measure cosmic noise at 3.8 Mc./s. from an Earth satellite.

Cosmic noise absorption measurements at Stanford, California, and Pullman, Washington

Results of cosmic noise absorption measurements at 27.5 Mc made at Stanford, California, and Pullman, Washington, during 1958 are presented. A method introduced by Mitra and Shain of extracting F-layer absorption from total absorption and an extension of this method to remove D-layer absorption are described. Subtracting these two components from the total absorption leaves an extra component of absorption. The diurnal and annual variation of all these components is presented graphically and discussed. Errors in the cosmic noise curves are discovered and corrected for. The cause of these errors and its relation to assumptions of the cosmic noise absorption method is discussed.

Cosmic ray soft component measurements during a flight from scandinavia across the North Pole and around Asia and Europe

During the geophysical year cosmic-ray measurements, including those with neutron monitors, were to be made at a number of stations in the northern polar region. Plans called for the collection of data on the soft component variations across this region along two meridians as opposite to each other as possible. With the aid of the Scandinavian Airlines System this prof ect was undentaken, the neutron monitor being returned along the usual commercial fiight routes over the southern parts of Asia and Europe. The survey includes several regions inaccessible by shipborne instruments. Some of the results of data taken so far are graphically shown. (A.C.)

Extra-atmospheric cosmic ray dosage during the large solar flare of 23 February 1956.

During the solar flare cosmic measurements were carried out on a world- wide scale. Though most of the measurements were made at sea level and mountain altitudes, synoptic evaluation of observations made at different geometric latitudes permits inference to be drawn about extra-atmospheric intensity. This intensity was so large that it seems of interest to investigate what ionization might be encountered if human beings should be caught by a large solar flare in extra-atmospheric flight. The neutron intensity of cosmic radiation at sea level during the flare showed 36 times its normal value 21 minutes after the onset of visible activity on the sum and them returned to normal in about 20 hours. At the same time as the above measurements a balloon reaching 50,000 ft recorded 4times normal total ionization. If a 3000% increase in the total ionization at 80,000 ft is reflected in a 15% increase in neutron intensity at sea level, the increase of ionization at great heights must have been tremendous. The implications of exposure hazards in interplanetary space during a large flare are ominous. (A.C.)

Cosmic ray intensity measurements at Bangalore 3° N. (mag.)

Cosmic ray intensity measurements at Bangalore 3° N. (mag.)