Browsing by Author "Lee, PJ"

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    Measurement of 236U in environmental media
    (Elsevier, 2000-10) Hotchkis, MAC; Child, DP; Fink, D; Jacobsen, GE; Lee, PJ; Mino, N; Smith, AM; Tuniz, C
    The long-lived uranium isotope 236U (T1/2=23.4 Ma) is produced by 235U neutron capture and builds up to high levels in nuclear fuel. It has been distributed in the environment as a result of nuclear activities including nuclear explosions, accidents at nuclear plants, dumping of nuclear waste and releases from nuclear facilities. 236U is a potentially useful tracer of irradiated uranium for nuclear safeguards or other applications, due to its virtual absence in natural samples (236U:238U ratio ∼10−10 in uranium ore). We have measured 236U in soil and sediment reference materials (IAEA 375, 135 and 300) by accelerator mass spectrometry (AMS). The AMS system on the ANTARES accelerator has been upgraded to make such measurements possible. The system, including sample preparation procedures, is described and the results discussed. © 2000 Elsevier Science B.V.
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    Rapid thermal annealing of neutron transmutation doped silicon
    (Australian Nuclear Science and Technology Organisation, 1987-10) Lawson, EM; Lee, PJ
    Rapid thermal annealing of neutron transmutation doped silicon wafers is shown to be an alternative to the normal furnace annealing procedure. A prototype incoherent light rapid thermal annealing 4.5 kW furnace has been constructed which can raise the temperature of 75mm diameter silicon wafers to 1120°C. Successful annealing is demonstrated by comparing the resistivities of the wafers with those from the furnace annealed standards. Deep level transient spectrometry has been performed to show that there are no electrically active deep level impurities present. Although there is evidence for crystalline slip it does not appear to affect the results.