The High-Altitude Water Cherenkov (HAWC) Observatory in M\'exico: The Primary Detector

The High-Altitude Water Cherenkov (HAWC) observatory is a second-generation continuously operated, wide field-of-view, TeV gamma-ray observatory. The HAWC observatory and its analysis techniques build on experience of the Milagro experiment in using ground-based water Cherenkov detectors for gamma-ray astronomy. HAWC is located on the Sierra Negra volcano in M\'exico at an elevation of 4100 meters above sea level. The completed HAWC observatory principal detector (HAWC) consists of 300 closely spaced water Cherenkov detectors, each equipped with four photomultiplier tubes to provide timing and charge information to reconstruct the extensive air shower energy and arrival direction. The HAWC observatory has been optimized to observe transient and steady emission from sources of gamma rays within an energy range from several hundred GeV to several hundred TeV. However, most of the air showers detected are initiated by cosmic rays, allowing studies of cosmic rays also to be performed. This paper describes the characteristics of the HAWC main array and its hardware.Comment: Accepted for publications in Nuclear Inst. and Methods in Physics Research, A (2023) 168253 ( https://www.sciencedirect.com/science/article/abs/pii/S0168900223002437 ); 39 pages, 14 Figure

Procesos de contaminación en el sureste de México

Los humedales constituyen ambientes diversos de la zona costera con una de las más altas productividades del planeta. Nuestro país Cuenta con una vasta región de estos ecosistemas con en el Golfo de México cuya riqueza biológica representa un aporte económico importante así como un factor social determinante; es por ello que en este trabajo se presentan los diferentes grupos de contaminantes generados por las actividades humanas, que son acumulados en el agua. los sedimentos y los organismos, sobre todo aquellos destinados al consumo humano y cuyo contenido de sustancias peligrosas como cadmio, plomo, mercurio, hidrocarburos aromáticos del petróleo, plaguicidas organoclorados, representa una amenaza ecológica y de salud pública

Presencia de metales en sedimentos recientes y organismos de la laguna Sontecomapan, Veracruz, México

In this paper are presented the results of the analysis of metals in sediments and biota from Sontecompn lagoon, Veracruz, during 1991-1992. In the sediemnts the metals with higher concentrations were Nickel (Ni), Chromium (Cr), Zinc (Zn), and Cooper (Cu). These elements were lso present in molluks bivalves (Crassostrea rhizophorae and Brchidontes exustus) as well as in the algae ( Cladophoropsis membranacea) and in the aquatic phanerogamae (Ruppia maritima).En este estudio se dan a conocer los niveles de algunos metales (Cu, Co, Cr, Ni, Zn, Cd y Pb) determinados en los sedimentos y organismos bentónicos de la laguna de Sontecomapan, Veracruz durante el periodo de 1991-1992. Los resultdaos muestran que en los sedimentos los metales con mayor concentración fueron: níquel, cromo, zinc y cobre. Estos elementos también estuvieron presentes en los moluscos bivlvos (Crassostrea riophorae y Brachidontes exustus), en la alga (Cladophoris membranacea) y la fanerógama acuática (Ruppia maritima), siendo mas altas las concentraciones en los bivalvos

Organochlorine pesticides in lacustrine sediments and tilapias of Metztitlan, Hidalgo, Mexico

The organochlorine pesticides (OP) are very stable molecules, due to this stability; they are very resistant in the environment and highly related to fat tissues with a wide diffusion property and an average time life higher then 10 years. We studied sediments (November 2001, April and June 2002) and organisms collected in April and July (2002) from the lacustric zone of Metzitlán, Hidalgo, Mexico. The analysis was performed according to UNEP/IAEA (1982) (sediments) and UNEP/FAO/IOC/IAEA (1986) (organisms) methods. Three chemical families of organochlorine pesticides were identified and analyzed to determine posible toxicological risk. The principal organochlorine compounds found in sediments were g-HCH, d-HCH, p,p'-DDT and the endosulfan sulfate; these xenobiotics come from agriculture lands near the river and lake, used intensively, and most probably carried by the rain and rain flows into the main water body. In the tilapias tissue, p,p'-DDD y d-HCH were detected. The average concentrations of organochlorine pesticides in sediments were within the internacional limits for freshwater benthonic fauna, although lindane (g-HCH) was near the limit. The fish were above the criteria established in the local legislation (NOM-027-SSA1-1993 y NOM-028-SSA1-1993)