A survey of recent studies of the correlation between y-rays from latitudess b > 10° and gas tracers is presented. Results for the ranges 35—100 MeV and above 100 MeV from the SAS-2 satellite, and ...for energies between 70 and 5000 MeV from the COS-B satellite, are used to obtain an estimate of the y-ray emissivity spectrum for all forms of gas. Good agreement between the two experiments is found. A comparison is made between this spectrum (which is an average for a region some few hundred parsecs around the Sun) and that expected for recent estimates of the low energy electron spectrum in the local interstellar medium. If the pion-decay component is as expected for the demodulated interplanetary proton spectrum, then the electron spectrum must have a steep slope (differential index 2.8) below 1 GeV. If the pion contribution is smaller than expected, however, a flatter electron spectrum is allowable. The presence of a component of y-ray emission related to gas in molecular form is evident in both the SAS-2 and COS-B data. We discuss the correlation of the SAS-2 data with both components and show that the emissivities of each component can be independently determined. The longitude dependence of the emission is also discussed. Finally, an examination of the y-ray fluxes from specific dense clouds of molecular gas is made.
Introductory remarks Rochester, George Dixon; Wolfendale, Arnold Whittaker
Philosophical transactions of the Royal Society of London. Series A: Mathematical and physical sciences,
01/1975, Letnik:
277, Številka:
1270
Journal Article
The intriguing problem of the identification of the source of the cosmic radiation has presented a challenge since its discovery some 60 years ago. Measurement of the energy and isotropy of the ...radiation showed conclusively that one obvious source, the Sun, was not the main source. Even in 1938 it was clear from the discovery of extensive air showers that the cosmic-ray spectrum extended to at least 1016 eV and continuously running monitors indicated that the departure from isotropy was no greater than the statistical uncertainty of the measurements (i.e. about 1%). Recent results have raised the maximum observed primary particle energy to higher than 1020 eV and the departure from isotropy for particulate radiation, to less than 0.01 % at 5 x 1011 eV and 1% at 1017 eV. To these striking facts must now be added the great wealth of detailed knowledge which has come from the immense advances in technology in the past 30 years. On the cosmic-ray side these advances range from the flying of detectors and sophisticated equipment on great balloons near the top of the atmosphere to the imaginative flights of spacecraft far out into the Solar System, well away from the confusing effects of the Earth’s atmosphere and the magnetosphere. Such experiments have given the relative abundances and the energy spectra of a variety of atomic nuclei and of electrons and positrons, and the intensity, energy and spatial distribution of X-rays and y-rays.
The intriguing problem of the identification of the source of the cosmic radiation has presented a challenge since its discovery some 60 years ago. Measurement of the energy and isotropy of the ...radiation showed conclusively that one obvious source, the Sun, was not the main source. Even in 1938 it was clear from the discovery of extensive air showers that the cosmic-ray spectrum extended to at least 1016 eV and continuously running monitors indicated that the departure from isotropy was no greater than the statistical uncertainty of the measurements (i.e. about 1%). Recent results have raised the maximum observed primary particle energy to higher than 1020 eV and the departure from isotropy for particulate radiation, to less than 0.01 % at 5 x 1011 eV and 1% at 1017 eV. To these striking facts must now be added the great wealth of detailed knowledge which has come from the immense advances in technology in the past 30 years. On the cosmic-ray side these advances range from the flying of detectors and sophisticated equipment on great balloons near the top of the atmosphere to the imaginative flights of spacecraft far out into the Solar System, well away from the confusing effects of the Earth’s atmosphere and the magnetosphere. Such experiments have given the relative abundances and the energy spectra of a variety of atomic nuclei and of electrons and positrons, and the intensity, energy and spatial distribution of X-rays and y-rays.
Results are presented of an experiment to study the penetrating particles in the cosmic radiation deep underground, at a depth of 7500 m. w. e. (standard rock). The events recorded are attributable, ...in the main, to muons produced either in the atmosphere or by the interactions of neutrinos in the surrounding rock. The muons have been studied in some detail and it appears that the mean energy of the neutrino induced muons (probably less than about 30 GeV) is low compared with that of the muons of atmospheric origin. The significance of the celestial coordinates of the muons and the measured rate of neutrino- induced muons is discussed and the future experimental programme is indicated.
The rate of energy loss of high-energy cosmic ray muons Hayman, P. J.; Palmer, N. S.; Wolfendale, Arnold Whittaker
Proceedings of the Royal Society of London. Series A, Mathematical and physical sciences,
10/1963, Letnik:
275, Številka:
1362
Journal Article
The rate of energy loss of muons is examined by com paring the observed depth-intensity relation with that predicted from a knowledge of the sea-level energy spectrum of cosmic ray muons. The ...evidence for each of the parameters entering into the analysis is assessed and estimates are made of the sea-level muon spectrum up to 10000 GeV and the depth-intensity relation down to 7000 m.w.e. The effect of range-straggling on the underground intensities is considered and shown to be important at depths below 1000 m.w.e. Following previous workers the energy loss relation is written as -dE/dx=1.88+0.077 in E'm/mc2+bE MeV g-1 cm2, where E'm is the maximum transferrable energy in a /i-e collision and m is the muon mass. The first two terms give the contribution from ionization (and excitation) loss and the third term is the combined contribution from pair production, bremsstrahlung and nuclear interaction. The best estimate of the coefficient b from the present work is b = (3.95 + 0.25) x 10-6 g-1 cm2 over the energy range 500 to 10000 GeV, which is close to the theoretical value of 4.0 x 10-6 g-1 cm2. It is concluded that there is no evidence for any marked anomaly in the energy loss processes for muons of energies up to 10000 GeV.
Final results are presented of an experiment to study the interactions of cosmic ray neutrinos deep underground, at a depth of 7.6 x 105 g cm-2 (standard rock). Clear examples have been recorded of ...neutrino-induced muons, including cases of upward moving particles and neutrino interactions within the detector assembly itself. The observed rate of events is compared with expectation and conclusions are made about the variation of the inelastic cross-section with energy and the lower limit to the mass of the intermediate boson. An examination has also been made of the celestial coordinates of the detected neutrinos and details are presented.
An experiment has been performed in the Kolar Gold Fields in Southern India to search for the interaction products of cosmic ray neutrinos. In the course of four years operation of the detectors at a ...depth of 2316 m of rock, some 165 particles were recorded which were attributed to muons of atmospheric (as distinct from neutrino-) origin and the present paper describes the results of measurements on these particles. The measured vertical intensity at the depth in question (2316 m of Kolar rock corresponding to 7.6 x 105 g cm-2 of standard rock) is (1.1 ± 0.2) 10-6 m-2 s-1 sr-1. Including measurements at shallower depths by other workers, from sites elsewhere in the same Gold Fields, a best fit to the data gives the relation I(h) = 7.73 x 10-3 exp (–h/790) m-2 sr-1 s-1 for depth range 4000 < h < 9500 hg cm-2 Kolar rock (1 hg cm-2 = 102 g cm-2). An approximate estimate has been made of the mean energy of the atmospheric muons at the depth of operation; its value, ca. 330 GeV, is not inconsistent with the expected value.
A direct determination has been made of the cosmic ray spectrum underground at a depth of 38 m. w. e. under Castle Rock, Nottingham. The spectrum is based on measurements of 1010 particles traversing ...a magnetic spectrograph having a maximum detectable momentum of 8 GeV/c. By comparing this spectrum with the ground-level spectrum the energy loss of fast μ-mesons in penetrating the 38 m. w. e. of rock has been determined. It is shown that the energy loss for μ-mesons in the momentum range 7 to 15 GeV/c is as expected by theory, the collision process being responsible for most of the loss.
Results are presented of an experiment to study the penetrating particles in the cosmic radiation deep underground, at a depth of 7500 m.w.e. (standard rock). The events recorded are attributable, in ...the main, to muons produced either in the atmosphere or by the interactions of neutrinos in the surrounding rock. The muons have been studied in some detail and it appears that the mean energy of the neutrino induced muons (probably less than about 30 GeV) is low compared with that of the muons of atmospheric origin. The significance of the celestial coordinates of the muons and the measured rate of neutrino-induced muons is discussed and the future experimental programme is indicated.
