Enhancing sensitivity of portal monitoring at varying transit speed

The sensitivity of a portal monitoring system has been improved by introducing speed dependent integration time in the data processing of the count rate signal. Characterization and first tests have been performed using a pneumatically driven 137Cs point source, before deploying the system to a test point at a railway junction near Vienna. At 14 m/s the MDA could be reduced by a factor of two and at 28 m/s by a factor of three compared to a fixed integration time of 1 s, whereas high sensitivity at low speed remained unaffected.