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UBC Theses and Dissertations

The measurement of the angular correlation of internal pairs produced in light nuclei Olsen, William Charles


This thesis is primarily concerned with a description of a new apparatus for the measurement of the angular correlation of positron-electron pairs produced internally in high energy, electromagnetic transitions in light nuclei. The apparatus consists of two counter telescopes, operating in coincidence, enclosed in a steel vacuum vessel whose axis coincides with the direction of the beam of bombarding particles. Each telescope consists of a proportional counter and a plastic scintillator spectrometer operating in coincidence. Because of the light construction of the proportional counters, the telescopes have a low sensitivity to gamma rays. The scintillation counters permit the use of fast coincidence techniques and the analysis of complex spectra, the latter being the great advantage of this apparatus. One of the telescopes is fixed in position while the other can be rotated about the direction of the beam. The reliability of the apparatus was established from measurements of the angular correlation of the internal pairs from the well-known pair emitting state of 0¹⁶. Preliminary measurements of the angular correlation of the internal pairs from the 7.48 mev. level in B¹º indicate that this transition is a mixture of E1 and M1 type radiations, the El being the predominant one.

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