114 research outputs found

    Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

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    Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0νββ\nu \beta \beta), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0νββ\nu \beta \beta of \ce{^{136}Xe} with projected half-life sensitivity of 1.35×10281.35\times 10^{28}~yr. To reach this sensitivity, the design goal for nEXO is \leq1\% energy resolution at the decay QQ-value (2458.07±0.312458.07\pm 0.31~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay QQ-value for the nEXO design

    The Physics of the B Factories

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    The hidden costs of cheap group tours - a case study of business practices in Australia

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    This paper deals with an issue that has been identified in many markets where there are large numbers of package tourists. In Australia, there have been a number of studies undertaken into the use of a range of dubious business practices employed by Inbound Tour Operators (ITOs), particularly in the Korean market. The cause for this problem is identified as the minimization of the retail price of package tour by transferring part of the cost of the tour to ITOs in the destination country. Under this system, ITOs are paid a daily tour rate below their real costs and are forced to recover losses by employing a range of dubious business practices including forced shopping and kickbacks from shops. The paper models the normal operation of the package tour cycle where no business practices are used and compares this to the Korean package inbound market in Australia where the use of business practices of this nature is widespread
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