Mitigation of backgrounds from cosmogenic 137Xe in xenon gas experiments using 3He neutron capture

136Xe is used as the target medium for many experiments searching for 0¿ßß. Despite underground operation, cosmic muons that reach the laboratory can produce spallation neutrons causing activation of detector materials. A potential background that is difficult to veto using muon tagging comes in the form of 137Xe created by the capture of neutrons on 136Xe. This isotope decays via beta decay with a half-life of 3.8 min and a Q ß of ~4.16 MeV. This work proposes and explores the concept of adding a small percentage of 3He to xenon as a means to capture thermal neutrons and reduce the number of activations in the detector volume. When using this technique we find the contamination from 137Xe activation can be reduced to negligible levels in tonne and multi-tonne scale high pressure gas xenon neutrinoless double beta decay experiments running at any depth in an underground laboratory

Mitigation of backgrounds from cosmogenic Xe-137 in xenon gas experiments using He-3 neutron capture

[EN] Xe-136 is used as the target medium for many experiments searching for 0 nu beta beta. Despite underground operation, cosmic muons that reach the laboratory can produce spallation neutrons causing activation of detector materials. A potential background that is difficult to veto using muon tagging comes in the form of Xe-137 created by the capture of neutrons on Xe-136. This isotope decays via beta decay with a half-life of 3.8 min and a Q(beta) of similar to 4.16 MeV. This work proposes and explores the concept of adding a small percentage of He-3 to xenon as a means to capture thermal neutrons and reduce the number of activations in the detector volume. When using this technique we find the contamination from Xe-137 activation can be reduced to negligible levels in tonne and multi-tonne scale high pressure gas xenon neutrinoless double beta decay experiments running at any depth in an underground laboratory.The work described was supported by the Department of Energy under Award numbers DE-SC0019054 and DE-SC0019223. The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the European Union's Framework Program for Research and Innovation Horizon 2020 (2014-2020) under the Marie Skodowska-Curie Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Economia y Competitividad of Spain under grants FIS2014-53371-C04, the Severo Ochoa Program SEV-2014-0398 and the Maria de Maetzu Program MDM-2016-0692; the GVA of Spain under grants PROMETEO/2016/120 and SEJI/2017/011; the Portuguese FCT under project PTDC/FIS-NUC/2525/2014, under project UID/FIS/04559/2013 to fund the activities of LIBPhys, and under grants PD/BD/105921/2014, SFRH/BPD/109180/2015 and SFRH/BPD/76842/2011. Finally, we are grateful to the Laboratorio Subterraneo de Canfranc for hosting and supporting the NEXT experiment.Rogers, L.; Jones, BJP.; Laing, A.; Pingulkar, S.; Smithers, B.; Woodruff, K.; Adams, C.... (2020). 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A new emission reduction approach in MILD combustion through asymmetric fuel injection

This paper presents investigations with asymmetric liquid fuel injection (kerosene and biodiesel) into a combustor operating in MILD (moderate or intense low oxygen dilution) combustion regime with thermal inputs varying from 25 kW (6.34 MW/m(3))-53 kW (13.3 MW/m(3)). Effect of air-preheat temperature on temperature distribution and pollutant emissions is investigated by varying the incoming air temperature from 300 to 800K. The position of asymmetric fuel injection is optimized based on numerical studies to maximize internal recirculation rate, R-dil. Maximum R-dil values of 4.54 and 3.52 are obtained for asymmetric and symmetric fuel injection cases respectively. Different fuel injection pressures of 14, 30, and 48 bar with the same nozzle are used to achieve different mass flow rates of 2.5/2.45, 3.12/3.10, and 4.46/4.3 kg/h for kerosene/biodiesel fuels respectively. Shadowgraphy studies show that measured Sauter Mean Diameters (SMD) vary from 34 to 19 pm and 108 to 37 pm for kerosene and biodiesel respectively, with fuel injection pressure varying from 14 to 48 bar. The combustor showed increased flame stability up to a global equivalence ratio of phi=0.2 for asymmetric fuel injection compared to phi=0.6 in symmetric fuel injection case, due to higher temperatures measured in the central zone of combustor. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved

How the interaction of Listeria monocytogenes and Acanthamoeba spp. affects growth and distribution of the food borne pathogen

ISSN:0175-759