High-Energy Gamma-Ray Calibration Source

There are no long-lived gamma-ray calibration sources with energies above 3.5 MeV, which is an impediment to the calibration of high-purity-germanium (HPGe) and scintillation detectors used in cutting edge experiments in nuclear physics, astrophysics, and homeland security. In addition, there are growing safety and security concerns about the storage of radioactive sources currently in use. The calibration source must be inherently safe, compact, and suitable for use in the field, either with regular outlet power or batteries. Recent advances in Prompt Gamma-ray Activation Analysis (PGAA) with guided neutron beams have led to the precise calibration of neutron-capture gamma-ray sources with energies up to 10.8 MeV ¿ energies have been determined to less than10 eV, and intensities have been determined to better than 1percent over the entire energy range. In this project, these neutron-capture gamma-ray sources will be produced in a moderator/transducer surrounding a compact, low yield neutron generator, utilizing the D-D fusion reaction. The neutron generator, which will not require any cooling or vacuum pumping while operating, will use a compact power-pack-type high voltage supply. A low power, rugged plasma generator design, with hot filaments or spark gaps, will be installed in a sealed safety container. The low neutron flux will provide a gamma-ray source comparable in strength to traditional radioactive sources and no radiation would be emitted when the device is turned off. Calibration techniques to correct for attenuation of the gamma rays in the moderator also will be developed. Commercial Applications and other Benefits as described by the awardee: The DOE and the International Atomic Energy Agency (IAEA) must provide for the application of standards for the safety of nuclear installations and radioactive sources. The device should permit the easy calibration of HPGe detectors at high ¿-ray energies, at in-house installations or in the field, for the identification of nuclear and radioactive materials. In addition it will reduce security concerns about the storage of radioactive sources currently in use, will increase the available photon energies for calibrating, and will permit the more accurate calibration of HPGe detectors at energies up to 10 MeV.