Study of the Charge Spectrum of Extremely Heavy Cosmic Rays Using Combined Plastic Detectors and Nuclear Emulsions

Abstract

Tracks of 99 nuclei with 2 > 3 6 have been analyzed in a stack of Lexan polycarbonate, cellulose triacetate, and nuclear emulsion launched from Palestine, Texas, with an area-time factor of 900 m2 h. Although the mean deviation in charge assignment between plastics and emulsion was -3 units, there was no systematic variation. One nucleus with charge estimated to be 2-96 (p=0.95) was identified in all three detectors. Combining all available data, 33 events have been found with 2>70, giving for the important ratio (2>83)/ ( 7 0 5 2 5 8 3 ) the value -0.3. The weakness of the Pb peak relative to the Pt peak indicates that little radioactive decay of the transbismuth nuclei has occurred. These results favor supernova explosions within the galaxy as the major source of cosmic rays and suggest that their average lifetime is less than lo7 yr.

A database of charged cosmic rays

“…The presence of heavy Z < 30 (Freier et al 1948a,b) and extremely heavy Z ≥ 30 elements (Fowler et al 1967;Blanford et al 1969) in the cosmic radiation were among the main discoveries related to Galactic CR nuclei, which culminated with the discovery of a few Z > 90 events (Fowler et al 1970;O'Sullivan et al 1971;Price et al 1971). Isotopes and, in particular, the radioactive CR clocks were identified with more or less difficulties due to their decreasing abundance and mass separation with increasing atomic number:…”

CRDB: a database of charged cosmic rays

“…The presence of heavy Z < 30 (Freier et al 1948a,b), and extremely heavy Z ≥ 30 elements (Fowler et al 1967;Blanford et al 1969) in the cosmic radiation were among the main discoveries related to Galactic CR nuclei, which culminated with the discovery of a few Z > 90 events (Fowler et al 1970;O'Sullivan et al 1971;Price et al 1971). Isotopes and in particular the radioactive CR clocks were identified, with more or less difficulties due to their decreasing abundance and mass separation with increasing atomic number: 10 Be (Webber et al 1973c), 36 Cl (Young et al 1981), 26 Al (Webber 1982), and 54 Mn .…”

Observation of low-charge low-energy geomagnetically forbidden particles

“…Several large-area detectors have been flown by high-altitude balloons from the NCAR Balloon Facility in Palestine, Texas. The purpose of these experiments was to observe ultraheavy primary cosmlc-ray particles, i.e., Z > 30 or VVH particles, at relativistic energies [Fowler et al, 1967Blanford et al, 1969Blanford et al, , 1970Price et al, 1971]. The detectors consisted of layers of nuclear emulsions and plastics and a shifting mechanism that allowed discrimination between tracks formed during balloon ascent and descent and those formed during float at the ceiling altitude.…”