Measured

22020000180 0 00160oi~ 140"~~ 120~"'" 10008060-1 0 2 3 4 5 6Time (min.) afterX-ray irradiationFigure5.19: Decaytime of diamondsampleB afterexposure.Response at zero represents beforeirradiation level.It is apparent from the results above that UVR and strontium-90 irradiations which are usuallyused to prime low nitrogen CVD diamonds have not been successful in improving theperformance of this particular diamond stone. Other forms of sample passivation techniqueshave to be considered and employed. This however, is beyond the scope ofthe present study.5.9. Construction of diamond probeFollowing the performance of the constructed Test Probe (Mark I), two more diamond probeshave been constructed with similar electrical connections as in Mark I. The two probes namedas Mark IIA and lIB (Figures 5.20 and 5.21 respectively) were constructed using entirelytissue equivalent materials with carbon fibre providing both electrical contacts and shielding.Electrical insulation was provided by Teflon tubes. The outer casing ofthe probes was105