Are Portable Personnel Portal Monitors too sensitive?

The Human Monitoring Laboratory has field tested its Portable Personnel Portal (P3) Monitors using sources up to 1700 MBq (47 mCi) to determine the alarm distance as a function of activity. The results show that the P3 monitors are highly sensitive, so much so that siting will be a problem for multiple units if multiple alarms are to be avoided. Building materials will shield the monitors allowing units to be placed closer together than in the open where there is no shielding, but windows and doors reduce shielding and complicate the siting of multiple units. In either situation, careful prior thought should be given to siting the monitors and the logistics of the crowd control techniques.