Electron bifurcation mechanism and homoacetogenesis explain products yields in mixed culture anaerobic fermentations

Anaerobic fermentation of organic wastes using microbial mixed cultures is a promising avenue to treat residues and obtain added-value products. However, the process has some important limitations that prevented so far any industrial application. One of the main issues is that we are not able to predict reliably the product spectrum (i.e. the stoichiometry of the process) because the complex microbial community behaviour is not completely understood. To address this issue, in this work we propose a new metabolic network of glucose fermentation by microbial mixed cultures that incorporates electron bifurcation and homoacetogenesis. Our methodology uses NADH balances to analyse published experimental data and evaluate the new stoichiometry proposed. Our results prove for the first time the inclusion of electron bifurcation in the metabolic network as a better description of the experimental results. Homoacetogenesis has been used to explain the discrepancies between observed and theoretically predicted yields of gaseous H2 and CO2 and it appears as the best solution among other options studied. Overall, this work supports the consideration of electron bifurcation as an important biochemical mechanism in microbial mixed cultures fermentations and underlines the importance of considering homoacetogenesis when analysing anaerobic fermentations

Spectral density for a hole in an antiferromagnetic stripe phase

Using variational trial wave function based on the string picture we study the motion of a single mobile hole in the stripe phase of the doped antiferromagnet. The holes within the stripes are taken to be static, the undoped antiferromagnetic domains in between the hole stripes are assumed to have alternating staggered magnetization, as is suggested by neutron scattering experiments. The system is described by the t-t'-t''-J model with realistic parameters and we compute the single particle spectral density.Comment: RevTex-file, 9 PRB pages with 15 .eps and .gif files. To appear in PRB. Hardcopies of figures (or the entire manuscript) can be obtained by e-mail request to: [email protected]

Life Cycle Assessment of electricity production in Italy from anaerobic co-digestion of pig slurry and energy crops

This study aims to evaluate the environmental consequences and energy requirements of a biogas production system and its further conversion into bioenergy by means of the Life Cycle Assessment (LCA) methodology. To do so, an Italian biogas plant operating with pig slurry and two energy crops (maize and triticale silages) as feedstock was assessed in detail in order to identify the environmental hotspots. The environmental pro\ufb01le was estimated through six impact categories: abiotic depletion potential (ADP), acidi\ufb01cation potential (AP), eutrophication potential (EP), global warming potential (GWP), ozone layer depletion potential (ODP) and photochemical oxidation potential (POFP). An energy analysis related to the cumulative non-renewable fossil and nuclear energy demand (CED) was also performed, considering this indicator as an additional impact category. According to the results, the biomass production subsystem was identi\ufb01ed as the main environmental key issue in terms of ADP, AP, EP, ODP and CED, with contributions ranging from 26% to 61% of the total impact. Regarding ADP, ODP and CED, these results are mainly related with diesel requirements in agricultural machinery, derived combustion emissions and mineral fertilizers production. Concerning AP and EP the production \ufb01eld emissions derived from fertilizers application was observed as the main contributor. Concerning GWP, this step presents an environmental credit due to the uptake of CO2 during crop growth, which contributes to offset the GHG emissions. The bioenergy production plant signi\ufb01- cantly contributes to the environmental impact in categories such as GWP (43%) and POFP (59%), mostly related with emissions produced in the gas engine and biogas losses. Emissions derived from digestate storage contribute to AP (52%) and EP (41%). The use of the digestate as an organic fertilizer has a bene\ufb01cial role because this action avoids the production and use of mineral fertilizers. A sensitivity analysis was also conducted to assess the in\ufb02uence of variations in important parameters of biogas systems. The environmental pro\ufb01le of the biogas system turned out to be highly dependent on the selection of system boundaries and the allocation method. To sum up, this study aims to assess the environmental performance of a biogas technology available not only in Italy but also in other European countries. The environmental analysis of the process under study highlights the environmental bene\ufb01ts of the co-digestion processes, which not only produces biofuel but also reduces the disposal of solid wastes and produces digestate, with special value in the fertilization of agricultural soil

The NEXT White (NEW) detector

Conceived to host 5 kg of xenon at a pressure of 15 bar in the fiducial volume, the NEXT-White apparatus is currently the largest high pressure xenon gas TPC using electroluminescent amplification in the world. It is also a 1:2 scale model of the NEXT-100 detector for Xe-136 beta beta 0 nu decay searches, scheduled to start operations in 2019. Both detectors measure the energy of the event using a plane of photomultipliers located behind a transparent cathode. They can also reconstruct the trajectories of charged tracks in the dense gas of the TPC with the help of a plane of silicon photomultipliers located behind the anode. A sophisticated gas system, common to both detectors, allows the high gas purity needed to guarantee a long electron lifetime. NEXT-White has been operating since October 2016 at the Laboratorio Subterraneo de Canfranc (LSC), in Spain. This paper describes the detector and associated infrastructures, as well as the main aspects of its initial operation

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

Measurement of radon-induced backgrounds in the NEXT double beta decay experiment

The measurement of the internal 222Rn activity in the NEXT-White detector during the so-called Run-II period with 136Xe-depleted xenon is discussed in detail, together with its implications for double beta decay searches in NEXT. The activity is measured through the alpha production rate induced in the fiducial volume by 222Rn and its alpha-emitting progeny. The specific activity is measured to be (38.1 ± 2.2 (stat.) ± 5.9 (syst.)) mBq/m3. Radon-induced electrons have also been characterized from the decay of the 214Bi daughter ions plating out on the cathode of the time projection chamber. From our studies, we conclude that radon-induced backgrounds are sufficiently low to enable a successful NEXT-100 physics program, as the projected rate contribution should not exceed 0.1 counts/yr in the neutrinoless double beta decay sample

Background rejection in NEXT using deep neural networks

[EN] We investigate the potential of using deep learning techniques to reject background events in searches for neutrinoless double beta decay with high pressure xenon time projection chambers capable of detailed track reconstruction. The differences in the topological signatures of background and signal events can be learned by deep neural networks via training over many thousands of events. These networks can then be used to classify further events as signal or background, providing an additional background rejection factor at an acceptable loss of efficiency. The networks trained in this study performed better than previous methods developed based on the use of the same topological signatures by a factor of 1.2 to 1.6, and there is potential for further improvement.The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the Ministerio de Economia y Competitividad of Spain and FEDER under grants CONSOLIDER-Ingenio 2010 CSD2008-0037 (CUP), FIS2014-53371-C04 and the Severo Ochoa Program SEV-2014-0398; GVA under grant PROMETEO/2016/120. Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. JR acknowledges support from a Fulbright Junior Research Award.Renner, J.; Farbin, A.; Muñoz Vidal, J.; Benlloch-Rodríguez, J.; Botas, A.; Ferrario, P.; Gómez-Cadenas, J.... (2017). Background rejection in NEXT using deep neural networks. Journal of Instrumentation. 12. https://doi.org/10.1088/1748-0221/12/01/T01004S1

Demonstration of the event identification capabilities of the NEXT-White detector

[EN] In experiments searching for neutrinoless double-beta decay, the possibility of identifying the two emitted electrons is a powerful tool in rejecting background events and therefore improving the overall sensitivity of the experiment. In this paper we present the first measurement of the efficiency of a cut based on the different event signatures of double and single electron tracks, using the data of the NEXT-White detector, the first detector of the NEXT experiment operating underground. Using a 228Th calibration source to produce signal-like and background-like events with energies near 1.6 MeV, a signal efficiency of 71.6 ± 1.5 stat ± 0.3 sys% for a background acceptance of 20.6 ± 0.4 stat ± 0.3 sys% is found, in good agreement with Monte Carlo simulations. An extrapolation to the energy region of the neutrinoless double beta decay by means of Monte Carlo simulations is also carried out, and the results obtained show an improvement in background rejection over those obtained at lower energies.The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787NEXT; the European Union's Framework Programme for Research and Innovation Horizon 2020 (2014-2020) under the Marie Sklodowska-Curie Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Economia y Competitividad and the Ministerio de Ciencia, Innovacion y Universidades of Spain under grants FIS2014-53371-C04, RTI2018-095979, 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/FBD/105921/2014, SFRH/BPD/109180/2015 and SFRH/BPD/76842/2011; the U.S. Department of Energy under contracts number DE-AC02-06CH11357 (Argonne National Laboratory), DE-AC02-07CH11359 (Fermi National Accelerator Laboratory), DE-FG02-13ER42020 (Texas A&M) and DE-SC0019223/DE-SC0019054 (University of Texas at Arlington); and the University of Texas at Arlington. DGD acknowledges Ramon y Cajal program (Spain) under contract number RYC-2015-18820. We also warmly acknowledge the Laboratori Nazionali del Gran Sasso (LNGS) and the Dark Side collaboration for their help with TPB coating of various parts of the NEXT-White TPC. Finally, we are grateful to the Laboratorio Subterraneo de Canfranc for hosting and supporting the NEXT experiment.Ferrario, P.; Benlloch-Rodríguez, J.; Díaz López, G.; Hernando Morata, J.; Kekic, M.; Renner, J.; Usón, A.... (2019). Demonstration of the event identification capabilities of the NEXT-White detector. Journal of High Energy Physics (Online). (10):1-17. https://doi.org/10.1007/JHEP10(2019)052S11710M. Fukugita and T. Yanagida, Baryogenesis without grand unification, Phys. Lett.B 174 (1986) 45 [ INSPIRE ].EXO-200 collaboration, Improved measurement of the 2νββ half-life of136Xe with the EXO-200 detector, Phys. Rev.C 89 (2014) 015502 [ arXiv:1306.6106 ] [ INSPIRE ].XENON collaboration, Dark matter search results from a one ton-year exposure of XENON1T, Phys. Rev. Lett.121 (2018) 111302 [ arXiv:1805.12562 ] [ INSPIRE ].Caltech-Neuchâtel-PSI collaboration, Search for ββ decay in136Xe: new results from the Gotthard experiment, Phys. Lett.B 434 (1998) 407 [ INSPIRE ].NEXT collaboration, First proof of topological signature in the high pressure xenon gas TPC with electroluminescence amplification for the NEXT experiment, JHEP01 (2016) 104 [ arXiv:1507.05902 ] [ INSPIRE ].NEXT collaboration, The Next White (NEW) detector, 2018 JINST13 P12010 [ arXiv:1804.02409 ] [ INSPIRE ].M. Redshaw, E. Wingfield, J. McDaniel and E.G. Myers, Mass and double-beta-decay Q value of136Xe, Phys. Rev. Lett.98 (2007) 053003 [ INSPIRE ].NEXT collaboration, Initial results on energy resolution of the NEXT-White detector, 2018 JINST13 P10020 [ arXiv:1808.01804 ] [ INSPIRE ].NEXT collaboration, Energy calibration of the NEXT-White detector with 1% resolution near Qββ of136Xe, arXiv:1905.13110 [ INSPIRE ].NEXT collaboration, Electron drift properties in high pressure gaseous xenon, 2018 JINST13 P07013 [ arXiv:1804.01680 ] [ INSPIRE ].T.H. Cormen, C. Stein, R.L. Rivest and C.E. Leiserson, Introduction to algorithms, 2nd ed., McGraw-Hill Higher Education, U.S.A. (2001).NEXT collaboration, Calibration of the NEXT-White detector using83mKr decays, 2018 JINST13 P10014 [ arXiv:1804.01780 ] [ INSPIRE ].J. Martín-Albo, The NEXT experiment for neutrinoless double beta decay searches, Ph.D. thesis, Valencia U., IFIC, Valencia, Spain (2015).GEANT4 collaboration, GEANT4: a simulation toolkit, Nucl. Instrum. Meth.A 506 (2003) 250 [ INSPIRE ].J.J. Gomez-Cadenas et al., Sense and sensitivity of double beta decay experiments, JCAP06 (2011) 007 [ arXiv:1010.5112 ] [ INSPIRE ].NEXT collaboration, Radiogenic backgrounds in the NEXT double beta decay experiment, arXiv:1905.13625 [ INSPIRE ].NEXT collaboration, Background rejection in NEXT using deep neural networks, 2017 JINST12 T01004 [ arXiv:1609.06202 ] [ INSPIRE ].NEXT collaboration, Application and performance of an ML-EM algorithm in NEXT, 2017 JINST12 P08009 [ arXiv:1705.10270 ] [ INSPIRE ].NEXT collaboration, Secondary scintillation yield of xenon with sub-percent levels of CO2 additive for rare-event detection, Phys. Lett.B 773 (2017) 663 [ arXiv:1704.01623 ] [ INSPIRE ].NEXT collaboration, Electroluminescence TPCs at the thermal diffusion limit, JHEP01 (2019) 027 [ arXiv:1806.05891 ] [ INSPIRE ].R. Felkai et al., Helium-xenon mixtures to improve the topological signature in high pressure gas xenon TPCs, Nucl. Instrum. Meth.A 905 (2018) 82 [ arXiv:1710.05600 ] [ INSPIRE ].NEXT collaboration, Electron drift and longitudinal diffusion in high pressure xenon-helium gas mixtures, 2019 JINST14 P08009 [ arXiv:1902.05544 ] [ INSPIRE ].NEXT collaboration, Sensitivity of NEXT-100 to neutrinoless double beta decay, JHEP05 (2016) 159 [ arXiv:1511.09246 ] [ INSPIRE ].J. Muñoz Vidal, The NEXT path to neutrino inverse hierarchy, Ph.D. thesis, Valencia U., IFIC, Valencia, Spain (2018)

Electron drift properties in high pressure gaseous xenon

[EN] Gaseous time projection chambers (TPC) are a very attractive detector technology for particle tracking. Characterization of both drift velocity and di¿usion is of great importance to correctly assess their tracking capabilities. NEXT-White is a High Pressure Xenon gas TPC with electroluminescent ampli¿cation, a 1:2 scale model of the future NEXT-100detector, which will be dedicated to neutrinoless double beta decay searches. NEXT-White has been operating at Canfranc Underground Laboratory (LSC) since December2016. The drift parameters have been measured using 83mKr for a range of reduced drift ¿elds at two di¿erent pressure regimes, namely 7.2 bar and 9.1 bar. Theresults have been compared with Magboltz simulations. Agreement at the 5% level or better has been found for drift velocity, longitudinal di¿usion and transverse di¿usion.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 Programme for Research and Innovation Horizon 2020 (2014-2020) under the Marie Sklodowska-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 and FEDER through the program COMPETE, projects PTDC/FIS-NUC/2525/2014 and UID/FIS/04559/2013; the U.S. Department of Energy under contracts number DE-AC02-07CH11359 (Fermi National Accelerator Laboratory), DE-FG02-13ER42020 (Texas A&M) and de-sc0017721 (University of Texas at Arlington); and the University of Texas at Arlington. We also warmly acknowledge the Laboratorio Nazionale di Gran Sasso (LNGS) and the Dark Side collaboration for their help with TPB coating of various parts of the NEXT-White TPC. Finally, we are grateful to the Laboratorio Subterraneo de Canfranc for hosting and supporting the NEXT experiment.Simon, A.; Felkai, R.; Martinez-Lema, G.; Monrabal, F.; Gonzalez-Diaz, D.; Sorel, M.; Hernando Morata, JA.... (2018). Electron drift properties in high pressure gaseous xenon. Journal of Instrumentation. 13. https://doi.org/10.1088/1748-0221/13/07/P07013S13Nygren, D. (2009). High-pressure xenon gas electroluminescent TPC for 0-ν ββ-decay search. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 603(3), 337-348. doi:10.1016/j.nima.2009.01.222Gómez Cadenas, J. J., Álvarez, V., Borges, F. I. G., Cárcel, S., Castel, J., Cebrián, S., … Dias, T. H. V. T. (2014). Present Status and Future Perspectives of the NEXT Experiment. Advances in High Energy Physics, 2014, 1-22. doi:10.1155/2014/907067Martín-Albo, J., Muñoz Vidal, J., Ferrario, P., Nebot-Guinot, M., Gómez-Cadenas, J. J., … Cárcel, S. (2016). Sensitivity of NEXT-100 to neutrinoless double beta decay. Journal of High Energy Physics, 2016(5). doi:10.1007/jhep05(2016)159Álvarez, V., Borges, F. I. G., Cárcel, S., Castel, J., Cebrián, S., Cervera, A., … Díaz, J. (2013). Initial results of NEXT-DEMO, a large-scale prototype of the NEXT-100 experiment. Journal of Instrumentation, 8(04), P04002-P04002. doi:10.1088/1748-0221/8/04/p04002Álvarez, V., Borges, F. I. G., Cárcel, S., Castel, J., Cebrián, S., Cervera, A., … Díaz, J. (2013). Operation and first results of the NEXT-DEMO prototype using a silicon photomultiplier tracking array. Journal of Instrumentation, 8(09), P09011-P09011. doi:10.1088/1748-0221/8/09/p09011Álvarez, V., Borges, F. I. G. M., Cárcel, S., Castel, J., Cebrián, S., Cervera, A., … Díaz, J. (2013). Near-intrinsic energy resolution for 30–662keV gamma rays in a high pressure xenon electroluminescent TPC. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 708, 101-114. doi:10.1016/j.nima.2012.12.123Ferrario, P., Laing, A., López-March, N., Gómez-Cadenas, J. J., Álvarez, V., … Cebrián, S. (2016). First proof of topological signature in the high pressure xenon gas TPC with electroluminescence amplification for the NEXT experiment. Journal of High Energy Physics, 2016(1). doi:10.1007/jhep01(2016)104Pack, J. L., Voshall, R. E., & Phelps, A. V. (1962). Drift Velocities of Slow Electrons in Krypton, Xenon, Deuterium, Carbon Monoxide, Carbon Dioxide, Water Vapor, Nitrous Oxide, and Ammonia. Physical Review, 127(6), 2084-2089. doi:10.1103/physrev.127.2084Pack, J. L., Voshall, R. E., Phelps, A. V., & Kline, L. E. (1992). Longitudinal electron diffusion coefficients in gases: Noble gases. Journal of Applied Physics, 71(11), 5363-5371. doi:10.1063/1.350555Bowe, J. C. (1960). Drift Velocity of Electrons in Nitrogen, Helium, Neon, Argon, Krypton, and Xenon. Physical Review, 117(6), 1411-1415. doi:10.1103/physrev.117.1411Patrick, E. L., Andrews, M. L., & Garscadden, A. (1991). Electron drift velocities in xenon and xenon‐nitrogen gas mixtures. Applied Physics Letters, 59(25), 3239-3240. doi:10.1063/1.105744English, W. N., & Hanna, G. C. (1953). GRID IONIZATION CHAMBER MEASUREMENTS OF ELECTRON DRIFT VELOCITIES IN GAS MIXTURES. Canadian Journal of Physics, 31(5), 768-797. doi:10.1139/p53-070Hunter, S. R., Carter, J. G., & Christophorou, L. G. (1988). Low-energy electron drift and scattering in krypton and xenon. Physical Review A, 38(11), 5539-5551. doi:10.1103/physreva.38.5539Kobayashi, S., Hasebe, N., Hosojima, T., Ishizaki, T., Iwamatsu, K., Mimura, M., … Ishizuka, A. (2006). Ratio of Transverse Diffusion Coefficient to Mobility of Electrons in High-Pressure Xenon and Xenon Doped with Hydrogen. Japanese Journal of Applied Physics, 45(10A), 7894-7900. doi:10.1143/jjap.45.7894Álvarez, V., Borges, F. I. G., Cárcel, S., Cebrián, S., Cervera, A., Conde, C. A. N., … Esteve, R. (2013). Ionization and scintillation response of high-pressure xenon gas to alpha particles. Journal of Instrumentation, 8(05), P05025-P05025. doi:10.1088/1748-0221/8/05/p05025Lorca, D., Martín-Albo, J., Laing, A., Ferrario, P., Gómez-Cadenas, J. J., Álvarez, V., … Cebrián, S. (2014). Characterisation of NEXT-DEMO using xenon KαX-rays. Journal of Instrumentation, 9(10), P10007-P10007. doi:10.1088/1748-0221/9/10/p10007Kusano, H., Lopes, J. A. M., Miyajima, M., & Hasebe, N. (2013). Longitudinal and transverse diffusion of electrons in high-pressure xenon. Journal of Instrumentation, 8(01), C01028-C01028. doi:10.1088/1748-0221/8/01/c01028Henriques, C. A. O., Freitas, E. D. C., Azevedo, C. D. R., González-Díaz, D., Mano, R. D. P., Jorge, M. R., … Álvarez, V. (2017). Secondary scintillation yield of xenon with sub-percent levels of CO2 additive for rare-event detection. Physics Letters B, 773, 663-671. doi:10.1016/j.physletb.2017.09.017Obert, E. F. (1948). Compressibility Chart and the Ideal Reduced Volume. Industrial & Engineering Chemistry, 40(11), 2185-2186. doi:10.1021/ie50467a036Agostinelli, S., Allison, J., Amako, K., Apostolakis, J., Araujo, H., Arce, P., … Barrand, G. (2003). Geant4—a simulation toolkit. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 506(3), 250-303. doi:10.1016/s0168-9002(03)01368-8González-Díaz, D., Monrabal, F., & Murphy, S. (2018). Gaseous and dual-phase time projection chambers for imaging rare processes. 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Radiopurity assessment of the energy readout for the NEXT double beta decay experiment

[EN] The "Neutrino Experiment with a Xenon Time-Projection Chamber" (NEXT) experiment intends to investigate the neutrinoless double beta decay of 136Xe, and therefore requires a severe suppression of potential backgrounds. An extensive material screening and selection process was undertaken to quantify the radioactivity of the materials used in the experiment. Separate energy and tracking readout planes using different sensors allow us to combine the measurement of the topological signature of the event for background discrimination with the energy resolution optimization. The design of radiopure readout planes, in direct contact with the gas detector medium, was especially challenging since the required components typically have activities too large for experiments demanding ultra-low background conditions. After studying the tracking plane, here the radiopurity control of the energy plane is presented, mainly based on gamma-ray spectroscopy using ultra-low background germanium detectors at the Laboratorio Subterráneo de Canfranc (Spain). All the available units of the selected model of photomultiplier have been screened together with most of the components for the bases, enclosures and windows. According to these results for the activity of the relevant radioisotopes, the selected components of the energy plane would give a contribution to the overall background level in the region of interest of at most 2.4 × 10¿4 counts per keV, kg and year, satisfying the sensitivity requirements of the NEXT experiment.Special thanks are due to LSC directorate and staff for their strong support for performing the measurements at the LSC Radiopurity Service. We are really grateful to Grzegorz Zuzel for the radon emanation measurements. The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the Ministerio de Economia y Competitividad of Spain under grants FIS2014-53371-C04 and the Severo Ochoa Program SEV-2014-0398; the GVA of Spain under grant PROMETEO/2016/120; the Portuguese FCT and FEDER through the program COMPETE, project PTDC/FIS/103860/2008; the U.S. Department of Energy under contracts number DE-AC02-07CH11359 (Fermi National Accelerator Laboratory) and DE-FG02-13ER42020 (Texas A & and the University of Texas at Arlington.Cebrian, S.; Perez, J.; Bandac, I.; Labarga, L.; Álvarez-Puerta, V.; Azevedo, CDR.; Benlloch-Rodriguez, JM.... (2017). Radiopurity assessment of the energy readout for the NEXT double beta decay experiment. Journal of Instrumentation. 12. https://doi.org/10.1088/1748-0221/12/08/T08003S12Avignone, F. T., Elliott, S. R., & Engel, J. (2008). Double beta decay, Majorana neutrinos, and neutrino mass. Reviews of Modern Physics, 80(2), 481-516. doi:10.1103/revmodphys.80.481Martín-Albo, J., Muñoz Vidal, J., Ferrario, P., Nebot-Guinot, M., Gómez-Cadenas, J. J., … Cárcel, S. (2016). Sensitivity of NEXT-100 to neutrinoless double beta decay. Journal of High Energy Physics, 2016(5). doi:10.1007/jhep05(2016)159Renner, J., Farbin, A., Vidal, J. M., Benlloch-Rodríguez, J. M., Botas, A., Ferrario, P., … Borges, F. I. G. (2017). Background rejection in NEXT using deep neural networks. Journal of Instrumentation, 12(01), T01004-T01004. doi:10.1088/1748-0221/12/01/t01004Dafni, T., Álvarez, V., Bandac, I., Bettini, A., Borges, F. I. G. M., Camargo, M., … Conde, C. A. N. (2016). Results of the material screening program of the NEXT experiment. Nuclear and Particle Physics Proceedings, 273-275, 2666-2668. doi:10.1016/j.nuclphysbps.2015.10.024Cebrián, S., Pérez, J., Bandac, I., Labarga, L., Álvarez, V., Barrado, A. I., … Cárcel, S. (2015). Radiopurity assessment of the tracking readout for the NEXT double beta decay experiment. Journal of Instrumentation, 10(05), P05006-P05006. doi:10.1088/1748-0221/10/05/p05006Wang, X., Chen, X., Fu, C., Ji, X., Liu, X., Mao, Y., … Zhang, T. (2016). Material screening with HPGe counting station for PandaX experiment. Journal of Instrumentation, 11(12), T12002-T12002. doi:10.1088/1748-0221/11/12/t12002Barrow, P., Baudis, L., Cichon, D., Danisch, M., Franco, D., Kaether, F., … Wulf, J. (2017). Qualification tests of the R11410-21 photomultiplier tubes for the XENON1T detector. Journal of Instrumentation, 12(01), P01024-P01024. doi:10.1088/1748-0221/12/01/p01024Busto, J., Gonin, Y., Hubert, F., Hubert, P., & Vuilleumier, J.-M. (2002). Radioactivity measurements of a large number of adhesives. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 492(1-2), 35-42. doi:10.1016/s0168-9002(02)01280-9Nisi, S., Di Vacri, A., Di Vacri, M. L., Stramenga, A., & Laubenstein, M. (2009). Comparison of inductively coupled mass spectrometry and ultra low-level gamma-ray spectroscopy for ultra low background material selection. Applied Radiation and Isotopes, 67(5), 828-832. doi:10.1016/j.apradiso.2009.01.02