A study of low energy particles in cosmic rays

Abstract

A large aperture, scintillation counter telescope capable of efficient mass discrimination against muons (and protons if desired) has been operated in a search for low energy (B < 0.8), massive particles in the sea level cosmic radiation, irrespective of their charge. In the running time, no quark candidates were detected. The rate of low velocity quarks is given with 90% confidence as (DIAGRAM) The limit refers to particles within well defined velocity bands, these being a function of the particle mass and charge. Furthermore, from this search, an upper limit of ~10(^-7) has been placed on the fraction of U particles in the primary radiation, at low energies. This limit refers to particles with mass values in the range 2-50 GeV/c(^2). Deuterons have been detected at an intensity of (DIAGRAM)The fall off in the observed deuteron spectrum is consistent with that expected for deuteron production via 'pick up' processes. For conclusive particle identification from measurements of mass, charge and sign of charge, an ideal design of magnetic spectrometer was considered, which, with a combination of momentum and time of flight measurements, gave a mass precision of 10%. The air gap magnetic spectrometer constructed, was investigated with respect to its ability to accept and subsequently resolve some familiar, low energy ( ~ 0.6 GeV), massive particles in the cosmic radiation at sea level. The precision of particle mass determinations was found to be limited by the scattering contribution to the momentum precision and not by the time of flight precision. A time of flight precision of + Ins was attained using a technique which2incorporated two 5 cm thick, Im area, plastic scintillators separated by530.4 cm and each viewed edgewise on by a single 56 AVP Mullard photomultiplier, for the determination of the time of flight between the scintillators. An upper limit of 2.2 x l0(^-5)cm(^-2)sec(^-1)sterad(^-1) was placed on the tachyon flux with velocities > 1.6 c in the cosmic rays at sea level. This limit refers to tachyons able to penetrate the spectrometer and deposit > l.8MeV in each scintillator.