The Disintegration of High Energy Protons

Abstract

b) The formation of K 38 from calcium In a previous paper 3 results obtained by one of us in a study of the radioactivities induced in calcium by deuteron bombardment were reported. It was noted that a weak activity was observed in the potassium fraction separated chemically from the irradiated metal. It was suggested that this might be due to contamination, though it was thought, in view of the fact that the half-period did not agree with that of any well-known contaminant, that it might be due to K 38 formed thus:Ca 40 +H 2 ->K 38 +He 4 ; K 38 -+A 38 +e+.Following the production of K 38 by bombarding chlorine with alpha-particles, a search was made for this isotope in irradiated calcium. It has a sufficiently short half-life to have been unobservable in the previous experiments on accountThe coupling between light and heavy particles assumed in the Fermi theory of jS-decay makes it possible for high energy protons in passing through matter to transfer a considerable fraction of their energy to electrons and neutrinos. If we suppose that this coupling is a maximum for relative energies of the light and heavy particles of the order hc/R, with R the range of nuclear forces, and is small for much higher relative energies, the most important process which occurs, for sufficiently energetic protons, can be pictured as a sort of photodisintegration of the proton by the contracted Coulomb field of a passing nucleus, the proton changing into a neutron and emitting a positron and a neutrino. With a coupling of the type described, and of of the time needed for the chemical separation adopted.Calcium metal was, therefore, bombarded with deuterons for half an hour and, following solution in HC1 and the addition of inactive KC1, potassium was precipitated by means of perchloric acid and ethyl alcohol. In consequence the precipitate was contaminated with radioactive scandium. 3 However, on correcting for this it was found that K 38 was present, the decay curve corresponding to a half-period of 7.6 ±0.2 minutes. This curve is reproduced in Fig. 5.The decay of this precipitate was measured until its corrected intensity was less than the natural leak of the electroscope, but no evidence was obtained of the 12.4 hour period of K 42 . The expected reaction Ca 44 +H 2 ->K 42 +He 4 ; K 42 ->Ca 42 +e~ would thus appear to be rather improbable. V. CONCLUSIONIn conclusion we wish to thank the staff of the Radiation Laboratory for their cooperation, and especially Professor E. O. Lawrence for his interest and encouragement. The investigation has been aided by grants to the laboratory from the Research Corporation, the Chemical Foundation and the Josiah Macy, Jr. Foundation. the magnitude required by the proton-neutron forces, processes involving more than one pair of light particles will be relatively rare. The cross section for the disintegration of a proton of energy E is found to be of the order 27r(h/Mc)RZW In 2 {E/Mc 2 ),and is very small, even for heavy nuclei. The mean energy given to the positron per disintegration is of the ord...

Photoproduction of dileptons and photons in p−p collisions at the Large Hadron Collider energies

“…Since its conveniences and simplicity, the equivalent photon approximation (EPA) , which can be traced to early work by Fermi, Weizsäcker and Williams (1934), and Landau and Lifshitz (1934), has been widely used for the approximate calculation of the various processes in relativistic heavy ion collisions [1][2][3][4][5][6][7]. By treating the moving electromagnetic fields of charged particles as a flux of real photons, many topics are studied such as photoproduction mechanism, particle and particle pairs production, meson production in electron-nucleon collisions, two-photon particle production mechanism, the determining of the nuclear parton distributions, and small x physics [8][9][10][11][12][13][14][15][16][17][18].…”

Iv. Théorie / Theorythe Equivalent Photon Approximation in One- And Two-Photon Exchange Processes

“…Similar equivalent photon spectra can be calculated in the case of incident hadrons (bosons, baryons, nuclei) instead of leptons, but in that case one should in principle include form factors [56]. 5. The equivalent photon approximation for twophoton exchange processes (a photon-photon collisions D ) .…”

“…whence we get the spectrum n(w) = an-2 bK2 o-' . Now we still must integrate over the surface of radius b in order to obtain the total equivalent photon spectrum and since we must normally take [5]…”

Validity of equivalent photon spectra and the photoproduction processes in p-p collisions

“…According to the fact that a fast moving charged particle carries electric fields that point radially outward and magnetic fields circling it, the field at a point some distance away from the trajectory of the particle resembles that of a real photon, Fermi replaced the electromagnetic fields from a fast-moving charged particle with an equivalent flux of photon. The number of photons with energy ω, n(ω), is given by the Fourier transform of the time-dependent electromagnetic field [2][3][4]. Therefore, the cross section of the electromagnetic interaction is approximated by the convolution of the photon flux with the relevant real photoproduction cross section.…”