Angular distributions of charged particles from nuclear reactions

Abstract

synopsis A description is given of equipment built for the measurement of angular distributions of charged particles released in nuclear reactions. Thin targets are bombarded by deuterons or protons accelerated by a cascadegenerator and analyzed by a magnet. Secondary particles from the target are detected by means of photographic emulsions placed at 15” intervals round the target. Results obtained with specific reactions (a.o. Be9(d, p)Be’O and C13(d, p)C14) will be dealt with in separate papers. 9 1. Introduction. The accuracy with which reaction-energies (Q-values) of charged particle reactions can be measured has been much improved in the last few years l). These measurements provide mass-differences between nuclei (if the final nucleus is left in the ground-state) or the positions of energy-levels in the final nucleus (if the final nucleus is left in an excited state). Other important data characterizing nuclear energy-states are their spin and parity but in general less is known about these quantities than about the positions of the states. Information about spin and parity can be obtained in many different ways one of which is the measurement of the angular distribution of particles released in nuclear reactions. This paper describes equipment built for this purpose. Measurements are confined to reactions in which both ingoing and outgoing particles are charged e.g. (d, p) or (d, a) reactions. Bombarding particles (generally deuterons) are produced in a magnetic ion-source and accelerated by the Utrecht cascadegenerator. After magnetic analysis they hit thin targets prepared by evaporation in vacuum onto thin aluminium backings. The reaction