Performance of a high sensitivity multi-element tissue equivalent proportional counter for radiation protection neutron monitoring measurements.

This study describes the performance of a novel design of compact multi-element tissue equivalent proportional counter (METEPC), which consists of 61 individual cylindrical counting volumes machined in a single block of tissue equivalent plastic. Each counting volume is a separate cylinder of internal diameter of 0.5 cm and height 5 cm. The performance of the METEPC was examined experimentally to obtain microdosimetric information, absorbed dose, dose equivalent, and sensitivity in the neutron energy range of 34 to 423 keV where commercially available tissue equivalent proportional counters (TEPCs) under respond as much as 40% of the ambient dose equivalent. A simple elongated cylindrical sampling geometry of METEPC provides very good estimates of microdosimetric average, y(D), and dosimetric quantities of interest, H*(10) and Q, which are comparable to those obtained with the conventional spherical sampling geometry of a standard TEPC. The sensitivity of METEPC is comparable to that of a conventional 12.7 cm diameter TEPC, which suggests that it is able to produce measurements in low dose rate radiation environments with the same precision in a given length of time as that obtained with the conventional TEPC. METEPC, being possibly the simplest design available in the multi-element geometrical configuration and approximately 9 times smaller in volume than that of a conventional 12.7 cm diameter TEPC, could form the basis of a portable monitoring system in mixed field radiation environments and may also be useful for radiation dosimetric measurements in beams of limited cross-sections and in phantoms.