Yash Pal
Articles written in Proceedings – Section A
Volume 36 Issue 2 August 1952 pp 75-96
Production and interaction of mesons at very high energies
D Lal Yash Pal B Peters M S Swami
A shower containing ∼360 charged and neutral shower particles produced by a magnesium nucleus of 2×1014e.v. provides a source of mesons whose interactions have been studied over an aggregate track length of about 3 meters in emulsion. It is first shown that in very large showers not only the incident energy can be determined but also the energy of the shower particles. The angular distribution of the shower particles agrees closely and their multiplicity is consistent with Fermi’s theory.
It is shown that the interaction cross-section of charged shower particles is geometric and that at an energy ∈ ∼ 1000
The charged mesons are
Charged shower particles as well as electrons produce electron-positron pairs with a cross-section of the order of that predicted by theory.
The number of neutral mesons decaying into
There exists evidence for the emission of neutral particles, different from neutrons, capable of producing meson showers.
The energy balance of the event suggests that a few shower particles carry an appreciable fraction of the total energy.
Volume 38 Issue 4 October 1953 pp 277-287
A method is described for constructing out of individual sheets of nuclear emulsion a detector of large volume and stopping power which can be used for observing entire chains of successive nuclear interaction and decay processes initiated by high energy particles.
Such a detector which had been exposed for several hours in the stratosphere has proved particularly valuable for detecting K-mesons and Hypersons* and for studying their modes of production and decay.
Volume 38 Issue 5 November 1953 pp 398-417
Observations on
In an emulsion block detector1 exposed in the stratosphere three cases of the production of
Volume 39 Issue 3 March 1954 pp 127-131
Production frequency of neutral pi-mesons in high energy interactions
Volume 39 Issue 4 April 1954 pp 214-214 Erratum
Volume 39 Issue 4 April 1954 pp 215-215 Erratum
Volume 40 Issue 3 September 1954 pp 114-118
An unusual example of a
Volume 40 Issue 4 October 1954 pp 151-157
On the construction of large nuclear emulsion block detectors
Volume 63 Issue 4 April 1966 pp 217-243
Evaluation of high energy natural neutrino experiments
The directional intensities of neutrinos of various types produced in the decay of cosmic ray secondaries in the earth’s atmosphere have been estimated. The calculated energy spectra are believed to be uncertain by <20% for neutrino energies up to 100 GeV.
Using these fluxes and making various assumptions about the behaviour of neutrino cross-section with energy, the energy spectra of neutrino-induced muons at large depths underground have been calculated. It is shown that a cross-section increasing only linearly with energy up to ∼ 100 GeV. would account only for about one-fifth of the preliminary counting rate observed in a recent underground experiment. A more rapid increase in cross-section is indicated somewhere between 10 GeV. and 100 GeV. and this is shown to be quantitatively consistent with the existence of a charged intermediate boson of mass 2 GeV. ∼ Mw < 5 GeV. (However see the note added in proof.)
The question of detecting high energy neutrino signals from extra-terrestrial sources is briefly discussed.
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