Radiation monitoring | Device roundup
Radseeker handheld radiation identifier20 April 2012
Smiths Detection’s RadSeeker, launched in 2011, is intended for nonspecialist police or customs personnel. The device is a new type of radiological detector that originated out of a formal US government competitive tender.
The hardware and software enclosed in its ruggedized plastic case is designed to simplify a complicated radiological picture.
Multifarious alarms at several levels and in varying modes—audible, visible, vibratory, earphone—warn the user of the presence of radioactive sources. In addition to gamma counts per second, neutron counts per minute and radioactivity in micro- or milli-Sv, the organic LED screen displays the device’s estimation of the isotopes present, and, crucially, which ones are natural background and which ones are threats. Connectivity including IEEE 802.11B/G/N Wi-Fi, ethernet and satellite phone connection via RF modem enables the transmission of detection information. Detections are time-stamped with location determined by latitude and longitude using global positioning satellites.
Inside the case are a moderated He-3 neutron detector (maximum count rate: 30,000/s) and a gamma spectrometer made of either sodium iodide, dose rate range 1 microrem/hr-12 mrem/hr (Cs-137), or lanthanum bromide, responsive over 1 microrem/hr-20 mrem/hr (Cs-137). The former material is less expensive but not as able to distinguish multiple simultaneous sources, according to Heddwyn Davies, CEO of Symetrica Security, the supplier of detector systems and part of the device’s electronics. Both models detect emissions in the 25 keV-3 MeV range, and identify isotopes using algorithms based on patterns of emission peaks. A customisable library of 41 nuclides is included as standard. Both the LaBr3 and the NaI versions interpret the presence of isotopes based on emissions according to ANSI N42.34 (2006). The US Domestic Nuclear Detection Office Human Portable Radiation Detection System programme, which has a slightly different emphasis than ANSI N42.34, has chosen to use LaBr3 which has a higher intrinsic resolution than NaI, according to Davies. Both versions incorporate a new technology to automatically stabilise the spectrum in real-time under conditions of varying temperature (the RadSeeker’s working range is -32°C to 50°C).