Abstract-Electrical

A variety of high purity silicon grown on the basis of different manufacturing technologies were exposed to gamma irradiation (up to a dose of 10' rad(Si)) and to neutron irradiation (up to a fluence of 10'' n/cm*). Observation was made of the conduction type and carrier concentration as a function of dose. The conversion point (n-Si to p-Si) of gamma jxradiated silicon was found to vary over 2 orders of magnitude of gamma dose for different manufacturers of high purity silicon independent of the initial carrier concentration. A systematic study of the radiition hardness of high punty silicon allows the development of silicon detectors working under harsh radiation environments operating over a wide range of dose. Another important aspect of this research is the development of neutron dosimeters with a wider range of response in terms of 1 MeV(Si) equivalent neutron fluence for calibration of neutron test facilities with unknown neutron energy spectrums. High punty silicon PIN diodes were calibrated using an epithermal neutron beam to determine whether response in terms of 1 MeV(Si) neutrons was independent of the calibration spectrum used.

A review is given of the use of germanium detectors for gamma spectroscopy. The advantages, principles of operation, and fabrication processes of semiconductor radiation detectors are described.

The U/n method is a well-established means of improving flux pinning and critical current performance in cuprate superconductors. The method involves the doping of the superconductor with 235 U followed by irradiation with thermal neutrons to promote fission. The resultant columnar damage tracks produced by the energetic fission products pin flux vortices and improve critical current performance in magnetic fields. No such improvement could be observed when the U/n method was applied to MgB 2 superconductor. No fission tracks could be observed in TEM, even for samples that were irradiated at the highest fluence. Gamma-ray spectroscopy indicated that fission had occurred in the expected way.