The detection and identification of radioactive isotopes are vital to preventing the proliferation of nuclear bombs and dirty bombs. Conventionally, detection systems are based on a combination of a scintillator and photomultiplier tubes (PMTs). The scintillator converts incident radiation into lower-energy light, which is then detected by the PMT. The output pulse height of the PMT provides a way to distinguish harmful materials from safe sources of radiation, such as medical and industrial isotopes.

The size of detection systems vary greatly. To inspect cargo containers and vehicles, portal radiation detectors are built with very large scintillator panels that have PMTs arranged along the outer edges of the panel. Conversely, manual inspection is also possible thanks to small pager-sized devices that detect the presence of radioactivity, as well as more sophisticated handheld units that take the further step of identifying the isotope.

Regardless of the size of the system, however, the ability to identify isotopes ultimately depends on the quality of the PMT and scintillator. Most Hamamatsu PMTs have specifications suited for isotope identification. Quite often, the limiting factor in the energy resolution of the device will be determined by the properties of the scintillator.

• R7400U: compact PMT for radiation pagers and for radiation detection with scintillang fibers.
• R6095: 28 mm head-on PMT with high energy resolution. Suitable for isotope identification with either handheld detectors or portal radiation detectors.
• R1924A: compact 25 mm head-on PMT with high energy resolution. Suitable for isotope identification (handheld or portal detectors).
• R980: 38 mm head-on PMT with high energy resolution. Suitable for portal radiation detectors.
• S3590 series: large-area silicon PIN photodiodes with optimum sensitivity for BGO and CsI(Tl) scintillators. Suitable for inexpensive radiation pagers and dosimeters.

Please contact us for information on other products which can be used for this application.