: Nuclear Interactions in a High Energy Multiplate Cloud Chamber

Citation

Luttermoser, Robert Lee (1963) : Nuclear Interactions in a High Energy Multiplate Cloud Chamber. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/R9C6-XA46. https://resolver.caltech.edu/CaltechTHESIS:04232012-110356302

Abstract

A large multiplate cloud chamber, 5 feet x 5 feet x 2 feet, was built for the purpose of investigating high energy nuclear interactions. The chamber contained eleven (11) steel plates of absorbing material, totaling two hundred fifty-four (254) grams/(centimeter)^2.

The cross-section for the transfer of small amounts of energy by incident primary particles of high energy was obtained by direct mensuration on the stereoscopic photographic negatives. The tracks of high energy cosmic ray particles were identified by observation of events in which at least 50 Bev was observed in a high energy nuclear interaction. These same tracks were searched for nuclear interactions of less than 10 Bev.

The analysis of six hundred thirty-six (636) cases yielded a mean free path in iron for the primary particles in producing the small interactions of (4.37 ± 1.46) x 10^3 grams/(centimeter)^2. The primary particle-nucleus cross-section was 21.1 ± 7.1 millibarns, which corresponded to a primary particle-nucleon cross-section of 0.38 ± 0.13 millibarns. These events were interpreted as resulting from peripheral collisions of the primary particles with the nucleons of the iron nuclei.

An independent part of the analysis was the effect of the geiger counter efficiency. Results indicated an absence of bias in high energy cross-section measurements which were based on the assumption that the selection of events for measuring the cross-section was independent of the counter efficiency. However, analysis also showed that the establishment of symmetric errors in such a cross-section is probably misleading.

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