Determination of the Cross Section for the Reactions 42Ca(n, p)42K and 43Ca(n, p)43K and Methods for Production of Carrier-Free Potassium Isotopes.

The cross sections for the (n,p) reactions of Ca/sup 42/ and Ca were determined by reactor irradiation of CaCO/sub 3/, carrierfree separation of potassium, and comparison of the K/sup 42/ and K/sup 43/ activities with the activity of Na/sup 24/ obtained in a monitor of pure Al. The measured cross sections were 2.1 plus or minus 0.4 and 1.5 plus or minus 0.3 mb for Ca/sup 42/ and Ca/sup 43/, respectively, the theoretically predicted ones, 1.3 and 4.5 mb. The carrier-free separation method utilized included: dissolution of the irradiated calcium carbonate in hydrochloric acid; sorption of the calcium on Dowex A 1 chelating resin; selective displacement of the potassium by means of ammonium chloride; substitution of the chloride with hydroxide, on an anion exchanger; and evaporation of the ammonlacal solution. This separation method should also be suitable for the production of carrier-free K/sup 42/or K/sup 43/ activities from enriched Ca/sup 42/ and Ca/sup 43/, and make possible the recovery, with a high yield, of the expensive, enriched calcium isotopes. A fission neutron flux of 5 x 10/sup 14/ s/sup -1/ cm/sup -2/ should yield after one day's irradiation of 10 mg Ca/sup 43/, about one mC of K/sup 43/. Somemore » advantages of carrier-free K/sup 43/ as compared with ordinary activated potassium are pointed out. (auth)« less