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

The measurement of the internal $^{222}$Rn activity in the NEXT-White detector during the so-called Run-II period with $^{136}$Xe-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 $^{222}$Rn and its alpha-emitting progeny. The specific activity is measured to be $(38.1\pm 2.2~\mathrm{(stat.)}\pm 5.9~\mathrm{(syst.)})$~mBq/m$^3$. Radon-induced electrons have also been characterized from the decay of the $^{214}$Bi 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.Comment: 28 pages, 10 figures, 6 tables. Version accepted for publication in JHE

Strategies to reengage patients lost to follow up in HIV care in high income countries, a scoping review

Background: Despite remarkable achievements in antiretroviral therapy (ART), losses to follow-up (LTFU) might prevent the long-term success of HIV treatment and might delay the achievement of the 90-90-90 objectives. This scoping review is aimed at the description and analysis of the strategies used in high-income countries to reengage LTFU in HIV care, their implementation and impact. Methods: A scoping review was done following Arksey & O'Malley's methodological framework and recommendations from Joanna Briggs Institute. Peer reviewed articles were searched for in Pubmed, Scopus and Web of Science; and grey literature was searched for in Google and other sources of information. Documents were charted according to the information presented on LTFU, the reengagement procedures used in HIV units in high-income countries, published during the last 15 years. In addition, bibliographies of chosen articles were reviewed for additional articles. Results: Twenty-eight documents were finally included, over 80% of them published in the United States later than 2015. Database searches, phone calls and/or mail contacts were the most common strategies used to locate and track LTFU, while motivational interviews and strengths-based techniques were used most often during reengagement visits. Outcomes like tracing activities efficacy, rates of reengagement and viral load reduction were reported as outcome measures. Conclusions: This review shows a recent and growing trend in developing and implementing patient reengagement strategies in HIV care. However, most of these strategies have been implemented in the United States and little information is available for other high-income countries. The procedures used to trace and contact LTFU are similar across reviewed studies, but their impact and sustainability are widely different depending on the country studied

The Next White (NEW) detector

[EN] Conceived to host 5 kg of xenón at a pressure of 15 bar in the ¿ducial volume,the NEXTWhite (NEW)apparatus is currently the largest high pressure xenon gas TPC using electroluminescent ampli¿cation in the world. It is also a 1:2 scale model of the NEXT-100 detector scheduled to start searching for ßß0¿ decays in 136Xe 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 2017 at the Canfranc Underground Laboratory (LSC), in Spain. This paper describes the detector and associated infrastructures.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 contract numbers DE-AC02-07CH11359 (Fermi National Accelerator Laboratory), DE-FG02-13ER42020 (Texas A&M), DE-SC0017721 (University of Texas at Arlington), and DE-AC02-06CH11357 (Argonne National Laboratory); 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.Monrabal, F.; Gomez-Cadenas, JJ.; Toledo Alarcón, JF.; Laing, A.; Álvarez-Puerta, V.; Benlloch-Rodriguez, JM.; Carcel, S.... (2018). The Next White (NEW) detector. Journal of Instrumentation. 13:1-35. https://doi.org/10.1088/1748-0221/13/12/P12010S13513Nygren, 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)104López-March, N. (2017). Sensitivity of the NEXT-100 detector to neutrinoless double beta decay. Journal of Physics: Conference Series, 888, 012243. doi:10.1088/1742-6596/888/1/012243Álvarez, 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/p05025Gehman, V. M., Seibert, S. R., Rielage, K., Hime, A., Sun, Y., Mei, D.-M., … Moore, D. (2011). Fluorescence efficiency and visible re-emission spectrum of tetraphenyl butadiene films at extreme ultraviolet wavelengths. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 654(1), 116-121. doi:10.1016/j.nima.2011.06.088Sanguino, P., Balau, F., Botelho do Rego, A. M., Pereira, A., & Chepel, V. (2016). Stability of tetraphenyl butadiene thin films in liquid xenon. Thin Solid Films, 600, 65-70. doi:10.1016/j.tsf.2016.01.006Silva, C., Pinto da Cunha, J., Pereira, A., Chepel, V., Lopes, M. I., Solovov, V., & Neves, F. (2010). Reflectance of polytetrafluoroethylene for xenon scintillation light. Journal of Applied Physics, 107(6), 064902. doi:10.1063/1.3318681Christophorou, L. G. (1988). Insulating gases. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 268(2-3), 424-433. doi:10.1016/0168-9002(88)90550-5Vijh, A. K. (1985). Relative electric strengths and polarizabilities of gaseous dielectrics. Materials Chemistry and Physics, 12(3), 287-296. doi:10.1016/0254-0584(85)90098-7Rebel, B., Hall, C., Bernard, E., Faham, C. H., Ito, T. M., Lundberg, B., … Wang, H. (2014). High voltage in noble liquids for high energy physics. Journal of Instrumentation, 9(08), T08004-T08004. doi:10.1088/1748-0221/9/08/t08004Cebrián, S., Pérez, J., Bandac, I., Labarga, L., Álvarez, V., Azevedo, C. D. R., … Cárcel, S. (2017). Radiopurity assessment of the energy readout for the NEXT double beta decay experiment. Journal of Instrumentation, 12(08), T08003-T08003. doi:10.1088/1748-0221/12/08/t08003Lung, K., Arisaka, K., Bargetzi, A., Beltrame, P., Cahill, A., Genma, T., … Yoshizawa, Y. (2012). Characterization of the Hamamatsu R11410-10 3-in. photomultiplier tube for liquid xenon dark matter direct detection experiments. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 696, 32-39. doi:10.1016/j.nima.2012.08.052Rodríguez, J., Toledo, J., Esteve, R., Lorca, D., & Monrabal, F. (2015). The front-end electronics for the 1.8-kchannel SiPM tracking plane in the NEW detector. Journal of Instrumentation, 10(01), C01025-C01025. doi:10.1088/1748-0221/10/01/c01025Carena, F., Carena, W., Chapeland, S., Chibante Barroso, V., Costa, F., Dénes, E., … von Haller, B. (2014). The ALICE data acquisition system. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 741, 130-162. doi:10.1016/j.nima.2013.12.015Martoiu, S., Muller, H., Tarazona, A., & Toledo, J. (2013). Development of the scalable readout system for micro-pattern gas detectors and other applications. Journal of Instrumentation, 8(03), C03015-C03015. doi:10.1088/1748-0221/8/03/c03015Toledo, J., Muller, H., Esteve, R., Monzó, J. M., Tarazona, A., & Martoiu, S. (2011). The Front-End Concentrator card for the RD51 Scalable Readout System. Journal of Instrumentation, 6(11), C11028-C11028. doi:10.1088/1748-0221/6/11/c11028Esteve, R., Toledo, J., Rodríguez, J., Querol, M., & Álvarez, V. (2016). Readout and data acquisition in the NEXT-NEW Detector based on SRS-ATCA. Journal of Instrumentation, 11(01), C01008-C01008. doi:10.1088/1748-0221/11/01/c01008Esteve, R., Toledo, J., Monrabal, F., Lorca, D., Serra, L., Marí, A., … Mora, F. (2012). The trigger system in the NEXT-DEMO detector. Journal of Instrumentation, 7(12), C12001-C12001. doi:10.1088/1748-0221/7/12/c12001Herzenberg, A. (1969). Attachment of Slow Electrons to Oxygen Molecules. The Journal of Chemical Physics, 51(11), 4942-4950. doi:10.1063/1.1671887Huk, M., Igo-Kemenes, P., & Wagner, A. (1988). Electron attachment to oxygen, water, and methanol, in various drift chamber gas mixtures. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 267(1), 107-119. doi:10.1016/0168-9002(88)90635-3Novella, P., Palmeiro, B., Simón, A., Sorel, M., Adams, C., … Zuzel, G. (2018). Measurement of radon-induced backgrounds in the NEXT double beta decay experiment. Journal of High Energy Physics, 2018(10). doi:10.1007/jhep10(2018)112Saldanha, R., Grandi, L., Guardincerri, Y., & Wester, T. (2017). Model independent approach to the single photoelectron calibration of photomultiplier tubes. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 863, 35-46. doi:10.1016/j.nima.2017.02.086Simón, A., Felkai, R., Martínez-Lema, G., Monrabal, F., González-Díaz, D., Sorel, M., … Álvarez, V. (2018). Electron drift properties in high pressure gaseous xenon. Journal of Instrumentation, 13(07), P07013-P07013. doi:10.1088/1748-0221/13/07/p07013Martínez-Lema, G., Morata, J. A. H., Palmeiro, B., Botas, A., Ferrario, P., Monrabal, F., … Para, A. (2018). Calibration of the NEXT-White detector using 83mKr decays. Journal of Instrumentation, 13(10), P10014-P10014. doi:10.1088/1748-0221/13/10/p1001

Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging

[EN] A new method to tag the barium daughter in the double-beta decay of Xe-136 is reported. Using the technique of single molecule fluorescent imaging (SMFI), individual barium dication (Ba++) resolution at a transparent scanning surface is demonstrated. A single-step photobleach confirms the single ion interpretation. Individual ions are localized with superresolution (similar to 2 nm), and detected with a statistical significance of 12.9 sigma over backgrounds. This lays the foundation for a new and potentially background-free neutrinoless double-beta decay technology, based on SMFI coupled to high pressure xenon gas time projection chambers.NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under Advanced Grant No. 339787-NEXT, the Ministerio de Economia y Competitividad of Spain under Grants No. FIS2014-53371-C04 and the Severo Ochoa Program SEV-2014-0398, the Generalitat Valenciana (GVA) of Spain under Grant No. 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 No. DE-AC02-07CH11359 (Fermi National Accelerator Laboratory) and No. DE-FG02-13ER42020 (Texas A&M) and No. DE-SC0017721 (University of Texas at Arlington), and the University of Texas at Arlington.Mcdonald, A.; Jones, B.; Nygren, D.; Adams, C.; Álvarez-Puerta, V.; Azevedo, C.; Benlloch-Rodríguez, J.... (2018). Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging. Physical Review Letters. 120(13):1-6. https://doi.org/10.1103/PhysRevLett.120.132504S1612013Chang, D., & Mohapatra, R. N. (1985). On a mechanism for small neutrino masses. Physical Review D, 32(5), 1248-1249. doi:10.1103/physrevd.32.1248Minkowski, P. (1977). μ→eγ at a rate of one out of 109 muon decays? Physics Letters B, 67(4), 421-428. doi:10.1016/0370-2693(77)90435-xMohapatra, R. N., & Senjanović, G. (1981). Neutrino masses and mixings in gauge models with spontaneous parity violation. Physical Review D, 23(1), 165-180. doi:10.1103/physrevd.23.165Fukugita, M., & Yanagida, T. (1986). Barygenesis without grand unification. Physics Letters B, 174(1), 45-47. doi:10.1016/0370-2693(86)91126-3Ostrovskiy, I., & O’Sullivan, K. (2016). Search for neutrinoless double beta decay. Modern Physics Letters A, 31(18), 1630017. doi:10.1142/s0217732316300172Ostrovskiy, I., & O’Sullivan, K. (2016). Errata: «Search for neutrinoless double beta decay». Modern Physics Letters A, 31(23), 1692004. doi:10.1142/s0217732316920048Dell’Oro, S., Marcocci, S., Viel, M., & Vissani, F. (2016). Neutrinoless Double Beta Decay: 2015 Review. Advances in High Energy Physics, 2016, 1-37. doi:10.1155/2016/2162659Gómez-Cadenas, J. ., Martín-Albo, J., Sorel, M., Ferrario, P., Monrabal, F., Muñoz, J., … Poves, A. (2011). Sense and sensitivity of double beta decay experiments. Journal of Cosmology and Astroparticle Physics, 2011(06), 007-007. doi:10.1088/1475-7516/2011/06/007Aseev, V. N., Belesev, A. I., Berlev, A. I., Geraskin, E. V., Golubev, A. A., Likhovid, N. A., … Zadorozhny, S. V. (2011). Upper limit on the electron antineutrino mass from the Troitsk experiment. Physical Review D, 84(11). doi:10.1103/physrevd.84.112003Gonzalez-Garcia, M. C., Maltoni, M., & Schwetz, T. (2016). Global analyses of neutrino oscillation experiments. Nuclear Physics B, 908, 199-217. doi:10.1016/j.nuclphysb.2016.02.033Álvarez, V., Borges, F. I. G. M., Cárcel, S., Carmona, J. M., Castel, J., Catalá, J. M., … Conde, C. A. N. (2012). NEXT-100 Technical Design Report (TDR). Executive summary. Journal of Instrumentation, 7(06), T06001-T06001. doi:10.1088/1748-0221/7/06/t06001Auger, M., Auty, D. J., Barbeau, P. S., Beauchamp, E., Belov, V., Benitez-Medina, C., … Cleveland, B. (2012). Search for Neutrinoless Double-Beta Decay inXe136with EXO-200. Physical Review Letters, 109(3). doi:10.1103/physrevlett.109.032505Moe, M. K. (1991). Detection of neutrinoless double-beta decay. Physical Review C, 44(3), R931-R934. doi:10.1103/physrevc.44.r931Danilov, M., DeVoe, R., Dolgolenko, A., Giannini, G., Gratta, G., Picchi, P., … Zeldovich, O. (2000). Detection of very small neutrino masses in double-beta decay using laser tagging. Physics Letters B, 480(1-2), 12-18. doi:10.1016/s0370-2693(00)00404-4Mong, B., Cook, S., Walton, T., Chambers, C., Craycraft, A., Benitez-Medina, C., … Auty, D. J. (2015). Spectroscopy of Ba andBa+deposits in solid xenon for barium tagging in nEXO. Physical Review A, 91(2). doi:10.1103/physreva.91.022505Brunner, T., Fudenberg, D., Varentsov, V., Sabourov, A., Gratta, G., Dilling, J., … Albert, J. B. (2015). An RF-only ion-funnel for extraction from high-pressure gases. International Journal of Mass Spectrometry, 379, 110-120. doi:10.1016/j.ijms.2015.01.003Flatt, B., Green, M., Wodin, J., DeVoe, R., Fierlinger, P., Gratta, G., … Weber, P. (2007). A linear RFQ ion trap for the Enriched Xenon Observatory. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 578(2), 399-408. doi:10.1016/j.nima.2007.05.123Sinclair, D., Rollin, E., Smith, J., Mommers, A., Ackeran, N., Aharmin, B., … Breidenbach, M. (2011). 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Measurement of radon-induced backgrounds in the NEXT double beta decay experiment

Abstract 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