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

Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0$\nu \beta \beta$), 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 0$\nu \beta \beta$ of \ce{^{136}Xe} with projected half-life sensitivity of $1.35\times 10^{28}$~yr. To reach this sensitivity, the design goal for nEXO is $\leq$1\% energy resolution at the decay $Q$-value ($2458.07\pm 0.31$~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 $Q$-value for the nEXO design

Hydrologic and Geomorphic Characteristics of the Bill Williams River, Arizona

The Bill Williams River system drains more than 5200 mi2 of west-central Arizona. It is the largest tributary of the Colorado River between the Virgin River and the Gila River. However, the name "Bill Williams River" is applied to a relatively short reach of this major drainage system-from the confluence of the Big Sandy and Santa Maria rivers to the Colorado River confluence at Lake Havasu (Figure 1). The watershed of the Bill Williams River spans very diverse physiography, however, ranging from high elevation forested mountains in the Central Highlands and low-lying, rugged desert mountains in the western Sonoran Desert. Historically, the hydrologic regime of the Bill Williams River was generally similar to its comparably sized counterparts to the east-the Verde and Salt Rivers. However, natural streamflow in the Bill Williams River is more variable overall than in these rivers. One report and two map sheets.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]

Historical Geomorphology and Hydrology of the Santa Cruz River

This report provides baseline information on the physical characteristics of the Santa Cruz River to be used by the Arizona Stream Navigability Commission in its determination of the potential navigability of the Santa Cruz River at the time of Statehood. The primary goals of this report are: (1) to give a descriptive overview of the geography, geology, climatology, vegetation and hydrology that define the character of the Santa Cruz River; and, (2) to describe how the character of the Santa Cruz River has changed since the time of Statehood with special focus on the stream flow conditions and geomorphic changes such as channel change and movement. This report is based on a review of the available literature and analyses of historical survey maps, aerial photographs, and U.S. Geological Survey stream gage records.Documents in the AZGS Document Repository collection are made available by the Arizona Geological Survey (AZGS) and the University Libraries at the University of Arizona. For more information about items in this collection, please contact [email protected]

Self-organized criticality in the olami-feder-christensen model

A system is in a self-organized critical state if the distribution of some measured events obeys a power law. The finite-size scaling of this distribution with the lattice size is usually enough to assume that the system displays SOC. This approach, however, can be misleading. In this work we analyze the behavior of the branching rate σ of the events to establish whether a system is in a critical state. We apply this method to the Olami-Feder-Christensen model to obtain evidences that, in contrast to previous results, the model is critical in the conservative regime only. PACs number(s): 64.60.L, 05.40, 05.70.L Keywords: SOC, Random Processes, and Non-equilibrium Thermodynamics. In spite of many efforts and more than a decade of studies, the presence of self-organized critical behavior in nature (and in some computer models) is a matter of controversy. The concept of self-organized criticality (SOC) wa