ON THE ABSENCE OF PHOTONS AMONG THE DECAY PRODUCTS OF THE 2.2 MICROSECOND MESON

1950 ◽  
Vol 28a (1) ◽  
pp. 29-43 ◽  
Author(s):  
E. P. Hincks ◽  
B. Pontecorvo
Keyword(s):  
Cosmic Ray ◽  
Geiger Counter ◽  
Decay Process ◽  
Meson Decay ◽  
Neutral Meson ◽  
Electronic Circuits ◽  
Graphite Block ◽  
Decay Products ◽  
Simultaneous Emission ◽  
Decay Event

An experiment is described which tests the hypothesis that the cosmic ray meson with a mean life of 2.2 μsec. decays into an electron and a photon. Geiger counter trays are used to select mesons incident on a graphite block, and to detect decay products emerging from the graphite. The electronic circuits record delayed coincidences that correspond to a decay event occurring between 0.6 and 5.3 μsec. after a meson is stopped. The absence of delayed coincidences of a type that could be attributed to the simultaneous emission of an electron and a photon, each of ~ 50 Mev., shows that the above hypothesis of the meson decay process is incorrect. The experiment also demonstrates the absence of a hypothetical unstable neutral meson among the decay products.

scholarly journals LONGEVITY AND HIGHEST-ENERGY COSMIC RAYS

1999 ◽  
Vol 08 (01) ◽  
pp. 117-122 ◽  
Author(s):  
PAUL H. FRAMPTON ◽  
BETTINA KESZTHELYI ◽  
Y. JACK NG
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
Grand Unification ◽  
Decay Products ◽  
Intermediate Particle

It is proposed that the highest energy ~1020 eV cosmic ray primaries are protons which are decay products of a superheavy particle, G. The protons may be decay products either directly of a nearby (galactic) Gor of a long-lived intermediate particle X which arises from decay of a distant (cosmological) G, then decays in or near our Galaxy. Such scenarios can occur in e.g. SU(15) grand unification and in some preon models.

Angular Distribution in Neutral Meson Decay

1958 ◽  
Vol 109 (4) ◽  
pp. 1326-1328 ◽  
Author(s):  
J. E. Leiss ◽  
R. A. Schrack
Keyword(s):  
Angular Distribution ◽  
Meson Decay ◽  
Neutral Meson

scholarly journals Contribution to the Background Rate of a Satellite X-Ray Detector by Spallation Products in a Caesium Iodide Crystal

1971 ◽  
Vol 10 ◽  
pp. 243-258
Author(s):  
C. S. Dyer ◽  
G. E. Morfill
Keyword(s):  
Cosmic Ray ◽  
Quantitative Agreement ◽  
Radioactive Isotopes ◽  
Background Rate ◽  
X Ray ◽  
Decay Products ◽  
Semi Empirical ◽  
Mev Protons ◽  
Iodide Crystal ◽  
General Method

AbstractThe energy spectra observed in a CsI crystal in the 20 keV–2 MeV range, due to the decay of radioactive isotopes produced in the crystal by bombardment with 155 MeV protons, are presented as a function of time after irradiation.It is shown that the large number of decay products produced by spallation can account for these spectra and that these spectra are in quantitative agreement with the predictions of a semi-empirical formula due to Rudstam, which gives the numbers of different isotopes produced. This formula is used to predict the spallation that would occur in such a crystal on board a satellite due to cosmic rays and passages through the South Atlantic Anomaly. Inspection shows that the spallation produced in the latter case is well approximated by that at 155 MeV. Hence the experimental results are used to explain previously observed background rates and to predict the background rates that would occur in the U.K.5 X-ray telescope of Imperial College. Using the Rudstam formula an estimate of cosmic ray induced background is also made.The relative importance of activity resulting from neutron interactions (atmospheric albedo and spacecraft secondaries) is considered.It is suggested that the Rudstam formula provides a general method of predicting induced radioactivity in satellite materials and that observed breaks in the diffuse cosmic X-ray spectrum could be due to inadequate allowance for this source of background.

Cosmic-ray flux variation with height in the atmosphere

1968 ◽  
Vol 46 (10) ◽  
pp. S1020-S1022 ◽  
Author(s):  
B. S. Chow ◽  
K. K. Wu ◽  
N. Simpson ◽  
V. D. Hopper
Keyword(s):  
Cosmic Radiation ◽  
Cosmic Ray ◽  
Geiger Counter ◽  
Proton Flux ◽  
Atmospheric Depth ◽  
Altitude Range ◽  
Flux Variation ◽  
Star Production ◽  
Cosmic Ray Flux ◽  
Made In

Analysis of emulsions exposed to cosmic radiation at atmospheric depths between 10 and 40 g/cm2 at λ = 47 °S geomagnetic on 11 December 1964 shows that there is little variation with altitude in proton flux in this altitude range. However, the total star production rate increases with increasing atmospheric depth but with a smaller slope than that measured by Geiger counter. Preliminary results obtained from exposures made in November 1965 at 8.5, 28.4, and 58 g/cm2 show that the values of proton flux at 8.5 and 58 g/cm2 are lower than that at 28.4 g/cm2. A study of the rate of production of stars at λ = 43° S and 9 g/cm2 over the period April 1962 to September 1966 shows some correlation with the ground-based neutron monitor count rate. The proton flux at the top of the atmosphere at latitude 47° S is estimated as 900 ± 100 protons/m2 sr s.

NEW MEASUREMENTS OF COSMIC RAY POSITRONS

1995 ◽  
Vol 10 (36) ◽  
pp. 2727-2732
Author(s):  
K.K. TANG
Keyword(s):  
Interstellar Medium ◽  
Secondary Production ◽  
Cosmic Ray ◽  
Simple Interpretation ◽  
Positron Fraction ◽  
Decay Products ◽  
Positron Flux ◽  
Balloon Experiments ◽  
Simple Picture ◽  
Existing Data

Cosmic ray electrons consists of mostly negative electrons and a relatively smaller flux of positrons. A simple interpretation is that all the positrons, together with an approximately equal flux of negative electrons, are decay products of pions created in the interaction of cosmic ray protons with the interstellar medium, and the remaining negative electrons are produced in primary cosmic ray sources. However, the existing data on the positron fraction (e+/e++e−) does not support this simple picture. While the positron flux around a few GeV can be explained by the secondary production, there are apparently excesses of positrons both at lower and higher energies. This has stimulated many interpretation and conjectures of new astrophysical sources of positrons. Recently, there are new measurements from four different balloon experiments. They begin to show some discrepancy with the old data. A brief summary of the new results and their impact is given here.

HIGH-ALTITUDE COSMIC RAY MEASUREMENTS AT FORT CHURCHILL

1960 ◽  
Vol 38 (5) ◽  
pp. 638-641 ◽  
Author(s):  
I. B. McDiarmid ◽  
D. C. Rose
Keyword(s):  
Solar Activity ◽  
High Altitude ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Geiger Counter ◽  
Low Energy ◽  
High Solar Activity ◽  
Energy Radiation ◽  
Cosmic Ray Intensity

Measurements with rocket-borne Geiger counters have been carried out at altitudes up to 250 km at Fort Churchill, Manitoba. The total primary cosmic ray intensity at a time near a solar maximum has been determined and compared with other measurements taken at times of high solar activity and also with other Geiger counter measurements obtained near a solar minimum. A low-energy radiation was observed whose intensity increased with altitude up to about 25% of the primary intensity at 250 km.

scholarly journals Electrochemical etching processes for the detection of neutrons and radon-decay products

2004 ◽  
Vol 19 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Luigi Tommasino
Keyword(s):  
Electrochemical Etching ◽  
Cosmic Ray ◽  
High Energy ◽  
Civil Aviation ◽  
Large Signal ◽  
Decay Products ◽  
Radon Decay ◽  
Personal Dosimetry ◽  
New Applications ◽  
Detection Characteristics

The electrochemical etching, because of its complexity, is of interest when it makes it possible to achieve detection characteristics which are not encountered with the chemical etching. These unique characteristics can be found for example for the personal dosimetry of low-energy neutrons around nuclear reactors and for the detection of both low- and high-energy cosmic-ray neutrons at civil aviation altitudes. In particular sufficiently large signal-to-noise ratios for cosmic ray neutron measurements can be achieved by using stack of polycarbonate- and/or CR-39-detectors, since the electrochemical etching processes make it possible: (a) the rapid scanning of large detector areas, and (b) the counting of coincidence events in paired detectors induced by a-few-microns long tracks. The detection of the radon decay products is hindered by the fact that their concentrations are altered in the vicinity of detector surface during the measurement. Polycarbonate detectors may be useful in solving these problems both because they register radon-decay products far away from the plated-out surface and they can be manufactured with any possible geometry and/or shape. However, it is possible to use several combinations of chemical and electrochemical etching steps which implies the possibility of new applications of track detectors for the registration of neutrons, cosmic rays and radon decay products.

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