Hidroxiapatita sintética de porosidad inducida: comparación con el hueso calcinado

RESUMEN: La hidroxiapatita (HAP), el compuesto mineral de los huesos, puede obtenerse sintéticamente por reacción entre cantidades estequiométricas de soluciones acuosas de fosfato de amonio y nitrato de calcio en condiciones básicas. El precipitado so somete a un doble lavado con agua destilada y se le incorporan fibras de celulosa (papel de filtro analítico molido) para obtener la porosidad deseada, en cantidades de 8, 16, 24, y 32%. Luego de filtrado, se seca y se calcina a 1050 °C por 2.5 h. Tanto el producto obtenido como muestras de hueso de camino cortical calcinado a 1050°C se caracterizaron por AAS, DRX, SEM, FTIR. Los resultados indicaron que tanto la HAP como el hueso calcinado presentan buena cristalidad y pureza, sin vestigios de fosfato de tipo tricálcico o tetracálcico. El contendido de carbonato es mayor al hueso calcinado que en la HAP sintética. Los espacios tubulares de la HAP y del hueso calcinado tienen cerca de 10 mm de diámetro, sin embargo, se observa mayor rugosidad y mayores agregados porosos en el hueso calcinado. Las composiciones químicas de ambas muestras son similares. Las muestras de HAO exhibieron características muy similares a las del hueso calcinado

Doping Liquid Argon with Xenon in ProtoDUNE Single-Phase: Effects on Scintillation Light

Doping of liquid argon TPCs (LArTPCs) with a small concentration of xenon is a technique for light-shifting and facilitates the detection of the liquid argon scintillation light. In this paper, we present the results of the first doping test ever performed in a kiloton-scale LArTPC. From February to May 2020, we carried out this special run in the single-phase DUNE Far Detector prototype (ProtoDUNE-SP) at CERN, featuring 770 t of total liquid argon mass with 410 t of fiducial mass. The goal of the run was to measure the light and charge response of the detector to the addition of xenon, up to a concentration of 18.8 ppm. The main purpose was to test the possibility for reduction of non-uniformities in light collection, caused by deployment of photon detectors only within the anode planes. Light collection was analysed as a function of the xenon concentration, by using the pre-existing photon detection system (PDS) of ProtoDUNE-SP and an additional smaller set-up installed specifically for this run. In this paper we first summarize our current understanding of the argon-xenon energy transfer process and the impact of the presence of nitrogen in argon with and without xenon dopant. We then describe the key elements of ProtoDUNE-SP and the injection method deployed. Two dedicated photon detectors were able to collect the light produced by xenon and the total light. The ratio of these components was measured to be about 0.65 as 18.8 ppm of xenon were injected. We performed studies of the collection efficiency as a function of the distance between tracks and light detectors, demonstrating enhanced uniformity of response for the anode-mounted PDS. We also show that xenon doping can substantially recover light losses due to contamination of the liquid argon by nitrogen