PERFORMANCE REQUIREMENTS FOR MONITORING PULSED, MIXED RADIATION FIELDS AROUND HIGH-ENERGY ACCELERATORS D. Forkel-Wirth

RADIATION FIELDS AND MONITORSIn preparation of the installation of a radiation monitoring system for the future LHC and its injectors comprehensive studies were performed to evaluate the suitability of different existing monitors for radiation protection measurements in pulsed and complex, mixed radiation fields. Different ionisation chambers were exposed to a mixed, high-energy reference field and it was shown that the results agreed well with Monte-Carlo calculations. In addition the chambers were exposed to short, high-intensity radiation pulses, where recombination effects and the capability of the electronics to process a high number of charges within very short time were studied in detail. These results are being used to optimize the design of the read-out electronics. Moreover, the results demonstrate that the investigated chambers are well suited to measure ambient dose equivalent and dose rates in these fields up to certain limits from where on recombination corrections should be taken into consideration. The so-called prompt, mixed radiation fields around high-energy accelerators are composed of charge d hadrons (protons, pions, kaons, etc.), neutrons, leptons (electrons, positrons, muons) and photons. The energies of these particles range from fractions of eV to several GeV. The particle and energy composition of the fields at a given point in or outside the accelerator tunnel depends strongly on its position with respect to the location of th e beam loss and the shielding used. As a general ru le radiation fields around high-energy accelerators are similar to cosmic radiation fields in the atmosphere. The time behaviour of the radiation fields follows the tim e structure of the pulsed particle beam. The pulse lengt