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名古屋大学年代測定総合研究センターシンポジウム報告

We have performed calculations in order to evaluate the vacuum conditions for the twohadron physics experiments WASA and PANDA. WASA is an ongoing experiment whereasPANDA is an experiment under construction. There is an interest in improving the vacuumconditions for these experiments in order to reduce background interactions. The experimentswere modelled as longitudinal conductance limited vacuum systems in the molecular flowregime and the calculations were performed with VAKLOOP. The approach was to fit amodel of WASA to measurement data and then extend this model to PANDA in order tomake predictions. The model of WASA was successful in the sense that it reproduced themeasurement data within the measurement uncertainty. The model of PANDA showed somediscrepancies in comparison with calculations from the Target Technical Design Report ofPANDA, but an overall similar pressure profile is obtained. Finally, we have considered a wayof improving the conditions at PANDA by including extra pumping capacity in the system,concluding that lowering the pressure at the interaction point for PANDA is challenging. Anoutlook for further modelling is to make a more detailed comparison between our model andthe one from the Target Technical Design Report.

The thesis concerns experimental studies of discharge excited lasers operating in the vacuum ultraviolet (VUV) region of the spectrum. The known molecular fluorine laser operating at 157nm, on a bound- to-bound transition of the F₂ molecule was selected for initial study. As a result of the work reported here the energy per pulse was increased by a factor of five (10mJ to 50mJ) from that of earlier F₂ lasers. Similary the working lifetime of the gas mixture was increased from a few shots to several thousand by the application of cryogenic gas purification techniques. These improvements have resulted in the development of a practical commercial F₂ laser. The performance characteristics of the fluorine laser and their relationship to the physical mechanisms are discussed. With the objective of achieving laser action in the 110 to 130nm region of the VUV a novel scheme is investigated. The scheme involves the production of a population inversion between the v'=1 level of the b¹π_u state of molecular nitrogen and high lying levels of the X¹Σ_g ground state. The excitation of the upper laser level involves production of N₂ molecules in the a¹π_g state by means of a pulsed discharge. Transfer of population from this intermediate 'a' state to the upper level is accomplished by absorption of radiation at 308nm from a discharge excited xenon chloride laser. The practicality of this scheme has been investigated to the extent that populations of the order of 10¹³ molecules per cm³ have been produced in the 'a' state and laser induced fluorescence on the 'b' to 'X' band has been observed. Under the conditions of "the present experiments the potential VUV gain is too small (10^-4cm<sup>-1>/sup>) to reach laser threshold. The problems of increasing the gain to reach threshold for a practical device are discussed.

Thesis (Ph. D.)--University of Adelaide, Dept. of Physics, 1983. / Includes bibliographical references (leaves [250]-268).

Thesis (Ph. D.)--Oregon Graduate Center, 1988.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: C. Grant Willson. Vita. Includes bibliographical references.

Thesis (B.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 34.

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 66-68.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 200-218).