Groundwater activation at the Superconducting Super Collider: a new design model.

A groundwater activation model was developed for use in designing the accelerators at the Superconducting Super Collider Laboratory. This model is based on the concept of a 4-m-thick "activation zone" surrounding the accelerator enclosure, which contains over 99% of the soil activation caused by beam losses. Empirical shielding formulae based on computer simulations indicate that the soil activation in the activation zone decreases exponentially with distance from the tunnel enclosure. From this assumption, the average activation in the activation zone is derived. It is shown that the average activity concentration in the activation zone is equal to the activity concentration 1 m from the accelerator enclosure. The activation concentration in the water averaged over the volume of the activation zone is compared to the drinking water standards. The goal of this model is to meet the drinking water regulatory standards by averaging the activation in the activation zone. Groundwater activation concentrations have been calculated for the Super Collider utilizing experimental measurements of production cross sections and leachability factors. Comparison is made to the groundwater activation criterion for both routine and accidental beam losses.

Particle distribution around a copper beam stop for 72 MeV protons.

Results are presented of an experiment to study neutron yields at different production angles from 72 MeV protons stopping in copper. Activation detectors were used to provide data on neutron energies and flux densities. The results of a spectrum unfolding analysis are presented and compared with a Monte Carlo calculation. Some dosimetric data are also included.