IN-SITU PRODUCTION OF RADIONUCLIDES AT GREAT DEPTHS

The depth dependent in-situ production of radionuclides has been measu red and calculated taking into account spallation reactions, reactions with captured negative and fast muons and background reactions, The f ollowing probabilities f of particle emission channels after mu(-) ca pture have been measured: O(mu(-),nu(mu)alpha pxn)Be-10, x = 1-3, f = (5.2 +/- 0.6) x 10(-3) and S(mu(-),nu(mu)alpha xn)Al-26, x = 2-4, 6, f = (1.4 +/- 0.4) x 10(-3). From the oxygen irradiation result for Be -10 and the known channel probability from silicon to Al-26, the produ ction ratio of Al-26 to log, after mu(-) capture in quartz has been de duced to be P(Al-26)/P(Be-10) = 7.2 +/- 1.2. The nucleon emission prob abilities after mu(-) capture have been determined for iron. The parti cle emission channel Fe(mu(-),nu(mu)xn)Mn-53, x = 1, 3-5 was estimated to 0.05 +/- 0.02. Natural depth profiles of Al-26 in quartz have been measured in Northern Bavaria up to depths of 250 m and have been comp ared with calculated profiles taking erosion into account, From this c omparison, the erosion rate in the last million years has been obtaine d to be about 10-20 mu m/y.