Further measurements and reassessment of the magnetic-monopole candidate

Journal Article · Fri Sep 01 00:00:00 EDT 1978 · Phys. Rev., D; (United States)

DOI:https://doi.org/10.1103/PhysRevD.18.1382· OSTI ID:6696847

Price, P B; Shirk, E K; Osborne, W Z; Pinsky, L S

Within the stack, consisting of 35 Lexan detectors and three nuclear emulsions, in which the unusual event was found, we have measured tracks of approx. 200 cosmic-ray nuclei with 26 < or = Z < or = 83, which provide an internal calibration of the response of the detectors. Our measurements in Lexan and in emulsion together show that the unusual particle produced a knockon-electron energy distribution incompatible with any known nucleus. The track etch rate and its gradient in Lexan give the quantity vertical-barZvertical-bar/..beta.. and, if the particle was a nucleus, a lower limit on its velocity. We found vertical-barZvertical-bar/..beta.. approx. = 114 at each of 66 positions in the Lexan stack extending over a range of approx. = 1.4 g/cm/sup 2/. The best fit to the Lexan data alone would be for a hypothetical superheavy element with Z approx. = 108 to 114 and ..beta.. such that Z/..beta.. approx. = 114. A known nucleus with 90 < or = Z < or = 96 would also give an acceptable fit to the Lexan data if it fragmented once in the stack with a loss of about 2 units of charge, keeping Z/..beta.. approx. = 114. A nucleus with Z < 90 could maintain Z/..beta.. approx. = 114 only by a properly spaced set of fragmentations. A nucleus with ..beta.. as low as 0.6 could fit the Lexan data only if it fragmented at least eight times in succession, with a probability approx. 10/sup -17/. In the 200-..mu..m G-5 emulsion, visual measurements of the track ''cores'' produced by relatively-low-energy electrons (< or approx. = 10 keV) are consistent with the Lexan result that the unusual particle had vertical-barZvertical-bar/..beta.. approx. = 114. However, measurements of the density of silver grains at radial distances greater than approx. 10 ..mu..m show that the particle produced far fewer high-energy (> or approx. = 50 keV) knockon electrons in each of the three emulsions than would a known nucleus with Z/..beta.. = 114.

• Research Organization: Physics Department and Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• OSTI ID: 6696847
• Journal Information: Phys. Rev., D; (United States), Vol. 18:5
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC RADIATION
MAGNETIC MONOPOLES
PARTICLE DISCRIMINATION
COSMIC NUCLEI
PHOTOGRAPHIC FILM DETECTORS
PLASTIC SCINTILLATION DETECTORS
POSTULATED PARTICLES
ELEMENTARY PARTICLES
IONIZING RADIATIONS
MEASURING INSTRUMENTS
MONOPOLES
NUCLEI
PARTICLE IDENTIFICATION
RADIATION DETECTORS
RADIATIONS
SCINTILLATION COUNTERS
SOLID SCINTILLATION DETECTORS
640101* - Astrophysics &amp; Cosmology- Cosmic Radiation
657007 - Electricity &amp; Magnetism- (-1987)