EFFECTS OF NUCLEAR RADIATION IN A LIQUID HYDROGEN MEDIA. Quarterly Report No. 2, April 1, 1961-June 30, 1961. PART I. CRYOGENIC APPARATUS FOR A LIQUID HYDROGEN IONIZATION FLOW CHAMBER. PART II. COLLECTION BETWEEN PARALLEL PLATES OF IONIZATION PRODUCED BY NUCLEAR RADIATION IN FLOWING CRYOGENIC MEDIA

A cryogenic apparatus for a liquid hydrogen ionization flow chamber, and the collection between parallel plates of ionization produced by nuclear radiation involving cryogenic media were investigated. A flow system was designed to measure the mobilities of the ions in liquid H as well as indirectly obtain the recombinition coefficients of the ions. The mobility and recombination characteristic of the ions will be studied by the use of a pyrex U'' tube completely immersed in liquid H and housing a shafted propeller to pull the liquid H continuously through the tube and a pitot tube, the design of which is based on M.I.T. wind tunnel experience. Propeller tests in water and liquid Ni demonstrate that linear velocities of 0-6 cm/sec with a maximum shaft speed of 2200 rpm can easily be attained by the pyrex U'' tube. The pitot tube is used when higher velocities are desired. The radiation source for the liquid H flow chamber will probably be Kr/sup 85/. After the Kr/sup 85/ source has been tested and evaluated, 400 mu Sr/sup 90/ microspheres will be investigated thoroughly as a possible ionization source. The H flow chamber or detector is a split plate ionization unit. A theoretical studymore » of this H flow (split plate) ionization chamber was made by applying theoretical models to experimental situations being planned. The following effects were studied: effect of space charge on the field and on the ion trajectories, processing data at different sourcedetector spacings based on an effective distance between source and ion chamber, processing data at different source-detector spacings based on an effective source position and on an ion chamber of finite length, and separate measurements of positive and negative ion mobility. Results of these studies indicate that space charge will not appreciably affect the values to be obtained for ion mobilities and ion recombination coefficient in liquid H. Two methods for processing the data were formulated to yield ( alpha / mu /sup +/ + mu /sup -/). An experiment for measuring mu /sup +/ and mu /sub -/ separately was described and analyzed. The ion currents in all experiments appear to be of measurable magnitude. (auth)« less