Radiation scintillator embedded with a converting medium to detect and discriminate the four species of ionizing radiation

摘要

A new nanoparticle loaded plastic scintillator embedded in a glass substrate detects and discriminates all species of radiation emitted from fissionable bomb making materials. The fast electron scintillating resin is doped with tailored charge conversion nanoparticles to produce characteristic optical pulses. The created optical pulses exit the detector, since the nanoparticles are appreciably smaller than the wavelength of light. Microsandblasting is used to etch deep cavities in the glass substrate forming independent optical paths. The doped resin is injected into the cavities and cured. A separate off-the-shelf PM tube linearly amplifies the created light pulse into a usable electrical signal. By using tailored nanoparticles, the physical mechanisms for converting different species of radiation into lower energy electrons allows for pulse height spectroscopy to discriminate between alpha, beta, gamma, and neutron radiation. A ~(90)Sr source was used to test the beta detector, which is loaded with W. The drop in count rates versus distance was found to be similar to traditional detectors. The gamma detector loaded with Pb nanoparticles was tested with a ~(60)Co source. The addition of Pb provided greater sensitivity to the gamma radiation. A ~(210)Pl source was used to test the glass doped scintillator. The count rates remained fairly constant for varying distances since alpha particles tend to travel in straight paths until losing most of their initial energy. The ~(157)Gd loaded scintillator was tested with an Am/Be source. ~(157)Gd has the largest thermal neutron absorption cross section at 255,000 barns and releases a usable characteristic 72keV electron in 39% of the capture reactions.