Personal Radiation Detectors:expectations and actual capabilities

摘要

The field of radiation control has considerably expanded during the recent fifteen years and its new type-the customs(border)radiation control was created.The peculiarities of such a control required new equipment to be developed and produced–from big stationary monitors being installed on the borders of the states to small high sensitive search instruments.Along with wide known stationary portal monitors of various types and hand-held instruments,so called Personal Radiation Detectors(PRD;they are also named"pager or pocket type"instruments)are widely available in recent years.PRD show some very attractive features:small dimensions,light weight and high sensitivity compared with usual personal dosimeters;two channels for gamma and neutron radiation detection;algorithm which ensures modes of operation for detection and location of radioactive sources.Because of these peculiarities,PRD are used for combating nuclear terrorism and illicit trafficking of nuclear and radioactive sources through state borders.PRD appeared to be so attractive to users that they became widely employed by customs,border guards and others special services of a number of countries.However,first opinions are stated that capabilities of PRD are overestimated and they are not fully suitable for some applications in contrast to the advertisements of manufacturers.In this paper,possible scenarios of PRD application are analyzed,activities of detected gamma and neutron sources are estimated,and the influence of background and detector sensitivity is discussed.It is shown that actually PRD do not correspond sometimes to expectations of users.This can result in incorrect decisions during detecting and locating the gamma and especially neutron sources.