Instrumentation for Nuclear Studies with Externally Focused Deuteron Beam from Ten-Mev Cyclotron

Abstract

A beam of ten‐Mev deuterons of about ½ μa has been focused on an area ¼ in. in diameter at the center of a 2‐ft. diameter reaction chamber 15‐ft. away from the cyclotron. In the center of the reaction chamber a gas target is supported with side ports so constructed that nuclear reaction products from the gas can be counted by a proportional counter mounted at the periphery of the chamber. The counter can be rotated through a Wilson seal to make any angle with the beam in the horizontal plane. At the exit of the reaction chamber a Faraday cup is supported. This can be removed to allow the beam to pass between the poles of an analyzing magnet for energy measurements. Tests with charged particle detectors such as a proportional counter or photographic plates show the background to be sufficiently low to allow good resolution of the products from the d‐d reactions. Using the d‐d reaction as a neutron source, background neutrons above 12 Mev are only about ten percent. However, the background neutrons above one Mev amount to about 25 times the neutrons from the d‐d reactions.