The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. Disciplines Engineering Physics | Physics Comments This is a manuscript of an article from Nuclear Instruments and Methods in Physics Research

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The use of contaminated surface water continues to be a pressing issue in areas of the world where people lack improved drinking water sources. In northern coastal Ecuador, many communities rely on untreated surface water as their primary source of drinking water. We undertook a study to explore how microscale river hydrodynamics affect microbial water quality at community water collection locations at three rivers with varying stream velocity and turbidity profiles. To examine how the distance from river shore and physiochemical water quality variables affect microbial contamination levels in the rivers; we collected a total of 355 water samples within six villages on three rivers; and tested for Escherichia coli concentrations using the IDEXX Quanti-tray method. We found that log10 E. coli concentrations decreased with increasing distance from shore (β = −0.017; p = 0.003). Water in the main channel had E. coli concentrations on average 0.12 log10 lower than within eddies along the river shore and 0.27 log10 lower between the sample closest to shore and any sample >6 m from the shore. Higher E. coli concentrations were also significantly associated with increased turbidity (β = 0.003; p < 0.0001) and decreased dissolved oxygen levels (β = −0.310; p < 0.0001). The results of this study can help inform community members about the safest locations to collect drinking water and also provide information on watershed scale transport of microbial contaminants between villages.

The fluvio lacustrine deposits of the Kathmandu Valley, Nepal are divided into four zones in terms of aquifer distribution. Deep confined aquifer in the south, GRI, medium depth interbedded aquifer, GRIT, shallow unconfined aquifer in the north, GRIII and an unconfined aquifer of thin sand and gravel deposit widely distributed on the surfaces of the terraces and other locations. Surface sediment deposits of fine to medium grain size referred to as surface gravel deposits, supply considerable quantity of water for residents of the valley through "Dharas" (stone spouts) and wells at superficial depths. The discharge is reported to double during monsoon period. General quality of water from these sources is considered good with some exceptions. For some years now, underground water source is believed to contribute about 40% of the city water supply. This is aggregated even further by pumping of the water in the private household with overdrafting going on for sometime. This overdrafting can be observed from the declining trend of the water levels in the tube wells. The total dynamic reserve of the valley is 12,730 m3/day. The average amount of infiltration from the rainfall is 17.2%. The discharge from "Dharas" adds to 1380 m3/day. Hence if the ground water is properly managed, overdrafting may not be necessary. Multipurpose projects specially in the northern zone should help induce artificial recharge. Otherwise, Kathmandu may face a potential disaster in the near future.

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