Unraveling the Particle Content of Cosmic Rays

An excerpt from a paper prepared for an international conference of historians of science, held in the fall of 1980 at Fermilab

Key Equations in the Tuljapurkar-Lee Model of the Social Security System

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POTENTIAL EFFECTS OF SUBSIDIZED LIVESTOCK INSURANCE ON LIVESTOCK PRODUCTION

Recent legislation has cleared the way for subsidized livestock price insurance. Such programs could increase production. Expected feeder cattle prices with and without subsidized insurance will be analyzed using E-V and Stochastic Dominance. Results will highlight the potential effects of the program on marketing risk and production decisions.Livestock Production/Industries, Risk and Uncertainty,

Crop Fertilization on Texas Alluvial Soils.

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Space-distribution of x-ray photoelectrons ejected from the K and L atomic energy-levels

A C.T.R. Wilson expansion-chamber was used to study the space-distribution of photoelectrons ejected from a gas by monochromatic x-rays. In agreement with Auger, and Watson and Van den Akker a more isotropic space-distribution was found for electrons ejected from the L energy-levels than for those ejected from the K energy-level. The distribution of the electrons from the L energy-levels became less isotropic with an increase in frequency of the incident radiation. For a given radiation, the average forward momentum of the electrons from the K energy-level was found to decrease with an increase in the binding energy of the parent atom. Within experimental error, however, for electrons from the K energy level, even for different binding energies, the average forward momentum remained the same for a given velocity of ejection of the electron. The average forward momentum of electrons from the L energy-level was greater than that for electrons from the K energy-level for a given velocity of ejection. The space-distribution of electrons from the K energy-level was in fair accord with the recent results of quantum mechanics

Energies of Cosmic-Ray Particles

Cloud chamber photographs of cosmic-ray tracks in a magnetic field up to 17,000 gauss are shown. On the assumption that the particles producing the tracks are travelling downward through the chamber rather than upward, particles of positive charge appear as well as electrons. From the specific ionization along the track it is concluded that the positives are protons, and are not nuclei of charge greater than unity. No evidence is uncovered demanding the introduction of a neutron for cosmic-ray phenomena. Eight examples of associated tracks are shown. Energies range from below 10^6 electron-volts to values in a few cases of the order of 10^9 electron-volts. Energy values for 70 tracks are listed. The scattering of cosmic particles in traversing a 6.0 mm lead plate is measured

Cosmic-ray bursts

In cloud-chamber experiments the frequent occurrence of associated tracks has been observed.(1) It has been pointed out that a simple binary collision cannot explain all the associated tracks.(2

Cosmic-Ray Positive and Negative Electrons

A determination of the specific ionization of cosmic-ray particles, first, by a count of the number of drops per cm along cosmic-ray tracks on cloud-chamber photographs and, second, by measurements of the energy loss in lead has shown that the great bulk of the cosmic-ray particles of positive charge are positive electrons. The primary ionization was found to be about 31 ion-pairs per cm in air at S.T.P., but the total energy loss represents about 120 ion pairs per cm in air. Approximately the same values of specific ionization were found for the positives as for the negatives. Positive and negative electrons were found to occur in nearly equal numbers and to have similar distributions in energy. Energy distribution curves are given for the positives and negatives. A brief description of the experimental procedure is given, and several track photographs are shown. In view of the discovery that hard gamma-rays of Th C′′ give rise to positives and negatives in pairs, similar to the effects found in cosmic-ray studies, it is concluded that the absorption of the Th C′′ rays is due in part to that by free negative electrons and in part to a nuclear effect which results in the production of pairs of positive and negative electrons, the former effect accounting for the greater part of the absorption of the Th C′′ rays. The symmetry in occurrence of the positive and negative electrons found in the cosmic-ray studies shows that the nuclear effect which results in the production of positive and negative electrons in pairs represents the predominant part of the absorption for the range of energies as high as those of the cosmic rays and that the absorption by free negative electrons is relatively small

The positive electron

Out of a group of 1300 photographs of cosmic-ray tracks in a vertical Wilson chamber 15 tracks were of positive particles which could not have a mass as great as that of the proton. From an examination of the energy-loss and ionization produced it is concluded that the charge is less than twice, and is probably exactly equal to, that of the proton. If these particles carry unit positive charge the curvatures and ionizations produced require the mass to be less than twenty times the electron mass. These particles will be called positrons. Because they occur in groups associated with other tracks it is concluded that they must be secondary particles ejected from atomic nuclei

The energy spectrum of the decay particles and the mass and spin of the mesotron

Energy values determined from curvature measurements of 75 cloud-chamber tracks of decay particles of cosmic-ray mesotrons at sea level, in a magnetic field of 7250 gauss, are here reported. The observed spectrum extends from 9 Mev to 55 Mev with an apparently continuous distribution of intermediate energy values and a mean energy of 34 Mev. The shape of the spectrum and the value of its upper limit are strong evidence that the mesotron disintegrates into an electron and two neutrinos. It is concluded that the mesotron has half-integral spin. The value of the observed upper limit of the energy spectrum corresponds to a mass value of the mesotron equal to 217±4 electron masses