Isotope identification backpacks (backpack radiation detectors) for clandestine monitoring of gamma and neutron radiation. Low power drain allows for many hours of uninterrupted monitoring. New multi-detector algorithms provide directionality to the user, enabling faster localization of nuclear sources. Additional user software may be integrated to allow fast and automatic data transmission to reachback centres.The RD-120 SAMpack Radiation Detection system can also continuously transmit a GPS location along with corresponding radiation levels and energy spectrum.