Science Collected Works - Theses
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ItemHigh-precision coincidence measurements of nuclear processes(University of Melbourne, 2009)High-precision coincidence techniques provide an excellent tool for probing and investigating nuclear structure. In this thesis, the results of two recent experiments conducted using these techniques will be presented; the calibration of a new phot on-tagging facility at MAX-lab, Lund University in Sweden, and the precision measurement of the half-life of the Fermi /3-decay of 140 at the School of Physics, University of Melbourne. These measurements require extreme timing accuracy. In my research, I have refined and developed new techniques for eliminating the traditional analogue and digital pathways in data acquisition and replaced these steps with the relatively new technique of high-speed signal digitisation. The results of the calibration measurement are in excellent agreement with theoretical calculations. Equally importantly, the measurement has also confirmed that the consistency of the performance of the new spectrometer magnets have not changed. Consequently, the MAX-lab photontagging facility has been declared ready for tagged-photon production. In the case of the 140 half-life measurement, this approach has allowed us to exploit a novel triple coincidence technique to significantly improve the signal-to-noise ratio and hence reduce the systematic uncertainties. The measured 140 half-life is found to be 70.623 � 0.053 s, and is in good agreement with the current world-average value. The resulting experimental Ft value from this new measurement of the Super allowed Fermi (3- decay of 140 may be used in the determination of the Vud element in the CKM matrix. This is to certify that: 1. the thesis comprises only my original work towards the PhD, 2. due acknowledgment has been made in the text to all other material used, 3. the thesis is less than 100,000 words in length, exclusive of tables, maps, bibliographies and appendices.
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ItemSearch for three rare B+ -> D+sX decays(University of Melbourne, 2008)
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ItemA precise measurement of the half life of the fermi b-decay of 26m A1(University of Melbourne, 2006)