ACTN3 R577X Polymorphism does not Influence Explosive Leg Muscle Power in Elite Volleyball Players

We examined the association of R577X polymorphism (rs1815739) in the α-actinin-3 (ACTN3) gene with “explosive” leg muscle power performance in a group of male and female elite volleyball players (n=66, 31 men, 35 women) and in a group of non-athletic male and female young adults (n=334, 243 men, 91 women). We assessed power performance by means of the vertical squat and counter-movement jump tests. We also determined whether the genotypic frequencies of the ACTN3 R577X genotypes differed between groups. We did not observe any effect of the ACTN3 R577X polymorphism on study phenotypes in both groups, regardless of gender (all P>0.05). Genotype frequencies were similar between volleyball and control groups (P=0.095). Moreover, we did not find an association between the ACTN3 R577X polymorphism and the likelihood of being an elite volleyball player using the dominant (RR vs RX+XX) and the recessive model (RR+RX vs XX). In summary, these findings suggest that the ACTN3 R577X polymorphism does not influence explosive leg muscle power in elite volleyball players

PADC nuclear track detector for ion spectroscopy in laser-plasma acceleration

[EN] The transparent polymer polyallyl-diglycol-carbonate (PADC), also known as CR-39, is widely used as detector for heavy charged particles at low fluence. It allows for detection of single protons and ions via formation of microscopic tracks after etching in NaOH or KOH solutions. PADC combines a high sensitivity and high specificity with inertness towards electromagnetic noise. Present fields of application include laser-ion acceleration, inertial confinement fusion, radiobiological studies with cell cultures, and dosimetry of nuclear fragments in particle therapy. These require precise knowledge of the energy-dependent response of PADC to different ion species. We present calibration data for a new type of detector material, Radosys RS39, to protons (0.2-3 MeV) and carbon ions (0.6-12 MeV). RS39 is less sensitive to protons than other types of PADC. Its response to carbon ions, however, is similar to other materials. Our data indicate that RS39 allows for measuring carbon ion energies up to 10 MeV only from the track diameters. In addition, it can be used for discrimination between protons and carbon ions in a single etching process.Project funded by CSIC, Grant No. 2018501082, and by the Spanish Ministerio de Ciencia, Innovacion y Universidades, project MdM-2016-0692-17-2 via a predoctoral grant of type Maria de Maeztu FPI. Nuclear track detector material and readout equipment have been provided by Radosys Ldt. (Budapest). The authors acknowledge the contributions and commitment of the CNA accelerator operators. MS would like to thank L. Ballesteros and J. Ortiz for their support with precision equipment.Seimetz, M.; Peñas, J.; Llerena, JJ.; Benlliure, J.; García López, J.; Millán-Callado, MA.; Benlloch Baviera, JM. (2020). PADC nuclear track detector for ion spectroscopy in laser-plasma acceleration. Physica Medica. 76:72-76. https://doi.org/10.1016/j.ejmp.2020.06.005S727676Kodaira, S., Kitamura, H., Kurano, M., Kawashima, H., & Benton, E. R. (2019). Contribution to dose in healthy tissue from secondary target fragments in therapeutic proton, He and C beams measured with CR-39 plastic nuclear track detectors. Scientific Reports, 9(1). doi:10.1038/s41598-019-39598-0Scampoli, P., Casale, M., Durante, M., Grossi, G., Pugliese, M., & Gialanella, G. (2001). Low-energy light ion irradiation beam-line for radiobiological studies. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 174(3), 337-343. doi:10.1016/s0168-583x(00)00622-4WADA, S., KOBAYASHI, Y., FUNAYAMA, T., NATSUHORI, M., ITO, N., & YAMAMOTO, K. (2002). Detection of DNA Damage in Individual Cells Induced by Heavy-ion Irradiation with an Non-denaturing Comet Assay. Journal of Radiation Research, 43(S), S153-S156. doi:10.1269/jrr.43.s153Gaillard, S., Pusset, D., de Toledo, S. M., Azzam, E. I., & Fromm, M. (2008). Distance distribution of bystander effects in alpha-particle irradiated cell populations using a CR-39-based culture dish. Radiation Measurements, 43, S34-S40. doi:10.1016/j.radmeas.2008.03.063Yogo, A., Maeda, T., Hori, T., Sakaki, H., Ogura, K., Nishiuchi, M., … Kondo, K. (2011). Measurement of relative biological effectiveness of protons in human cancer cells using a laser-driven quasimonoenergetic proton beamline. Applied Physics Letters, 98(5), 053701. doi:10.1063/1.3551623Séguin, F. H., Frenje, J. A., Li, C. K., Hicks, D. G., Kurebayashi, S., Rygg, J. R., … Padalino, S. (2003). Spectrometry of charged particles from inertial-confinement-fusion plasmas. Review of Scientific Instruments, 74(2), 975-995. doi:10.1063/1.1518141Daido, H., Nishiuchi, M., & Pirozhkov, A. S. (2012). Review of laser-driven ion sources and their applications. Reports on Progress in Physics, 75(5), 056401. doi:10.1088/0034-4885/75/5/056401Sinenian, N., Rosenberg, M. J., Manuel, M., McDuffee, S. C., Casey, D. T., Zylstra, A. B., … Petrasso, R. D. (2011). The response of CR-39 nuclear track detector to 1–9 MeV protons. Review of Scientific Instruments, 82(10), 103303. doi:10.1063/1.3653549Malinowska A, Szydłowski A, Jaskóła M, Korman A, Sartowska B, Kuehn T, Kuk M. Investigations of protons passing through the CR-39/PM-355 type of solid state nuclear track detectors, Rev Sci Instrum 84 (2013) 073511.Baccou, C., Yahia, V., Depierreux, S., Neuville, C., Goyon, C., Consoli, F., … Labaune, C. (2015). CR-39 track detector calibration for H, He, and C ions from 0.1-0.5 MeV up to 5 MeV for laser-induced nuclear fusion product identification. Review of Scientific Instruments, 86(8), 083307. doi:10.1063/1.4927684Seimetz, M., Bellido, P., García, P., Mur, P., Iborra, A., Soriano, A., … Benlloch, J. M. (2018). Spectral characterization of laser-accelerated protons with CR-39 nuclear track detector. Review of Scientific Instruments, 89(2), 023302. doi:10.1063/1.5009587Xiaojiao, D., Xiaofei, L., Zhixin, T., Yongsheng, H., Shilun, G., Dawei, Y., & Naiyan, W. (2009). Calibration of CR-39 with monoenergetic protons. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 609(2-3), 190-193. doi:10.1016/j.nima.2009.08.061Kodaira, S., Morishige, K., Kawashima, H., Kitamura, H., Kurano, M., Hasebe, N., … Ogura, K. (2016). A performance test of a new high-surface-quality and high-sensitivity CR-39 plastic nuclear track detector – TechnoTrak. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 383, 129-135. doi:10.1016/j.nimb.2016.07.002Ogura, K., Asano, M., Yasuda, N., & Yoshida, M. (2001). Properties of TNF-1 track etch detector. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 185(1-4), 222-227. doi:10.1016/s0168-583x(01)00816-3Malinowska, A., Jaskóła, M., Korman, A., Szydłowski, A., & Kuk, M. (2014). Characterization of solid state nuclear track detectors of the polyallyl-diglycol-carbonate (CR-39/PM-355) type for light charged particle spectroscopy. Review of Scientific Instruments, 85(12), 123505. doi:10.1063/1.4903755Bahrami, F., Mianji, F., Faghihi, R., Taheri, M., & Ansarinejad, A. (2016). Response of CR-39 to 0.9–2.5 MeV protons for KOH and NaOH etching solutions. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 813, 96-101. doi:10.1016/j.nima.2016.01.015Jeong, T. W., Singh, P. K., Scullion, C., Ahmed, H., Hadjisolomou, P., Jeon, C., … Ter-Avetisyan, S. (2017). CR-39 track detector for multi-MeV ion spectroscopy. Scientific Reports, 7(1). doi:10.1038/s41598-017-02331-wKanasaki, M., Hattori, A., Sakaki, H., Fukuda, Y., Yogo, A., Jinno, S., … Yamauchi, T. (2013). A high energy component of the intense laser-accelerated proton beams detected by stacked CR-39. Radiation Measurements, 50, 46-49. doi:10.1016/j.radmeas.2012.10.009Groza, A., Serbanescu, M., Butoi, B., Stancu, E., Straticiuc, M., Burducea, I., … Ganciu, M. (2019). Advances in Spectral Distribution Assessment of Laser Accelerated Protons using Multilayer CR-39 Detectors. Applied Sciences, 9(10), 2052. doi:10.3390/app9102052Zhang, Y., Wang, H.-W., Ma, Y.-G., Liu, L.-X., Cao, X.-G., Fan, G.-T., … Fang, D.-Q. (2019). Energy calibration of a CR-39 nuclear-track detector irradiated by charged particles. Nuclear Science and Techniques, 30(6). doi:10.1007/s41365-019-0619-xSeimetz, M., Bellido, P., Soriano, A., Garcia Lopez, J., Jimenez-Ramos, M. C., Fernandez, B., … Benlloch, J. M. (2015). Calibration and Performance Tests of Detectors for Laser-Accelerated Protons. IEEE Transactions on Nuclear Science, 62(6), 3216-3224. doi:10.1109/tns.2015.2480682Rana, M. A., & Qureshi, I. . (2002). Studies of CR-39 etch rates. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 198(3-4), 129-134. doi:10.1016/s0168-583x(02)01526-4Hermsdorf, D., Hunger, M., Starke, S., & Weickert, F. (2007). Measurement of bulk etch rates for poly-allyl-diglycol carbonate (PADC) and cellulose nitrate in a broad range of concentration and temperature of NaOH etching solution. Radiation Measurements, 42(1), 1-7. doi:10.1016/j.radmeas.2006.06.009Azooz, A. A., & Al-Jubbori, M. A. (2013). Interrelated temperature dependence of bulk etch rate and track length saturation time in CR-39 detector. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 316, 171-175. doi:10.1016/j.nimb.2013.09.001Jadrníčková I, Spurný F. To the spectrometry of linear energy transfer in charged particle beams by means of track-etch detectors, Radiat Measure 43(2008): S191–S194, proceedings of the 23rd International Conference on Nuclear Tracks in Solids. doi: 10.1016/j.radmeas.2008.04.010.Sadowski, M., Al-Mashhadani, E. M., Szydłowski, A., Czyzewski, T., Głowacka, L., Jaskóła, M., … Wieluński, M. (1995). Comparison of responses of CR-39 and PM-355 track detectors to fast protons, deuterons and 4He ions within energy range 0.2–4.5 MeV. Radiation Measurements, 25(1-4), 175-176. doi:10.1016/1350-4487(95)00066-nSadowski, M., Szydlowski, A., Jaskola, M., Czyzewski, T., & Kobzev, A. P. (1997). Comparison of responses of CR-39, PM-355, and CN track detectors to energetic hydrogen-, helium-, nitrogen-, and oxygen-ions. Radiation Measurements, 28(1-6), 207-210. doi:10.1016/s1350-4487(97)00069-3Henig, A., Steinke, S., Schnürer, M., Sokollik, T., Hörlein, R., Kiefer, D., … Habs, D. (2009). Radiation-Pressure Acceleration of Ion Beams Driven by Circularly Polarized Laser Pulses. Physical Review Letters, 103(24). doi:10.1103/physrevlett.103.245003Kar, S., Kakolee, K. F., Qiao, B., Macchi, A., Cerchez, M., Doria, D., … Borghesi, M. (2012). Ion Acceleration in Multispecies Targets Driven by Intense Laser Radiation Pressure. Physical Review Letters, 109(18). doi:10.1103/physrevlett.109.185006Palaniyappan, S., Huang, C., Gautier, D. C., Hamilton, C. E., Santiago, M. A., Kreuzer, C., … Fernández, J. C. (2015). Efficient quasi-monoenergetic ion beams from laser-driven relativistic plasmas. Nature Communications, 6(1). doi:10.1038/ncomms10170McGuffey, C., Raymond, A., Batson, T., Hua, R., Petrov, G. M., Kim, J., … Beg, F. N. (2016). Acceleration of high charge-state target ions in high-intensity laser interactions with sub-micron targets. New Journal of Physics, 18(11), 113032. doi:10.1088/1367-2630/18/11/113032Ma, W. J., Kim, I. J., Yu, J. Q., Choi, I. W., Singh, P. K., Lee, H. W., … Nam, C. H. (2019). Laser Acceleration of Highly Energetic Carbon Ions Using a Double-Layer Target Composed of Slightly Underdense Plasma and Ultrathin Foil. Physical Review Letters, 122(1). doi:10.1103/physrevlett.122.014803Hegelich, M., Karsch, S., Pretzler, G., Habs, D., Witte, K., Guenther, W., … Roth, M. (2002). MeV Ion Jets from Short-Pulse-Laser Interaction with Thin Foils. Physical Review Letters, 89(8). doi:10.1103/physrevlett.89.085002Henig, A., Kiefer, D., Markey, K., Gautier, D. C., Flippo, K. A., Letzring, S., … Hegelich, B. M. (2009). Enhanced Laser-Driven Ion Acceleration in the Relativistic Transparency Regime. Physical Review Letters, 103(4). doi:10.1103/physrevlett.103.045002Carroll, D. C., Tresca, O., Prasad, R., Romagnani, L., Foster, P. S., Gallegos, P., … McKenna, P. (2010). Carbon ion acceleration from thin foil targets irradiated by ultrahigh-contrast, ultraintense laser pulses. New Journal of Physics, 12(4), 045020. doi:10.1088/1367-2630/12/4/045020Jung, D., Yin, L., Albright, B. J., Gautier, D. C., Letzring, S., Dromey, B., … Hegelich, B. M. (2013). Efficient carbon ion beam generation from laser-driven volume acceleration. New Journal of Physics, 15(2), 023007. doi:10.1088/1367-2630/15/2/023007Dollar, F., Zulick, C., Matsuoka, T., McGuffey, C., Bulanov, S. S., Chvykov, V., … Krushelnick, K. (2013). High contrast ion acceleration at intensities exceeding 1021 Wcm−2. Physics of Plasmas, 20(5), 056703. doi:10.1063/1.4803082Kohno, R., Yasuda, N., Takeshi, H., Kase, Y., Ochiai, K., Komori, M., … Kanai, T. (2005). Measurements of Dose-Averaged Linear Energy Transfer Distributions in Water Using CR-39 Plastic Nuclear Track Detector for Therapeutic Carbon Ion Beams. 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Long-term wind resource assessment for small and medium-scale turbines using operational forecast data and measure-correlate-predict

Output from a state-of-the-art, 4 km resolution, operational forecast model (UK4) was investigated as a source of long-term historical reference data for wind resource assessment. The data were used to implement measure-correlate-predict (MCP) approaches at 37 sites throughout the United Kingdom (UK). The monthly and hourly linear correlation between the UK4-predicted and observed wind speeds indicates that UK4 is capable of representing the wind climate better than the nearby meteorological stations considered. Linear MCP algorithms were implemented at the same sites using reference data from UK4 and nearby meteorological stations to predict the long-term (10-year) wind resource. To obtain robust error statistics, MCP algorithms were applied using onsite measurement periods of 1-12 months initiated at 120 different starting months throughout an 11 year data record. Using linear regression MCP over 12 months, the average percentage errors in the long-term predicted mean wind speed and power density were 3.0% and 7.6% respectively, using UK4, and 2.8% and 7.9% respectively, using nearby meteorological stations. The results indicate that UK4 is highly competitive with nearby meteorological observations as an MCP reference data source. UK4 was also shown to systematically improve MCP predictions at coastal sites due to better representation of local diurnal effects

Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield

High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and double beta decay detection. The discrimination of the rare event through the topological signature of primary ionisation trails is a major asset for this type of TPC when compared to single liquid or double-phase TPCs, limited mainly by the high electron diffusion in pure xenon. Helium admixtures with xenon can be an attractive solution to reduce the electron diffu- sion significantly, improving the discrimination efficiency of these optical TPCs. We have measured the electroluminescence (EL) yield of Xe–He mixtures, in the range of 0 to 30% He and demonstrated the small impact on the EL yield of the addition of helium to pure xenon. For a typical reduced electric field of 2.5 kV/cm/bar in the EL region, the EL yield is lowered by ∼ 2%, 3%, 6% and 10% for 10%, 15%, 20% and 30% of helium concentration, respectively. This decrease is less than what has been obtained from the most recent simulation framework in the literature. The impact of the addition of helium on EL statistical fluctuations is negligible, within the experimental uncertainties. The present results are an important benchmark for the simulation tools to be applied to future optical TPCs based on Xe-He mixtures. [Figure not available: see fulltext.]

Energy calibration of the NEXT-White detector with 1% resolution near Q ββ of 136Xe

Excellent energy resolution is one of the primary advantages of electroluminescent high-pressure xenon TPCs. These detectors are promising tools in searching for rare physics events, such as neutrinoless double-beta decay (ββ0ν), which require precise energy measurements. Using the NEXT-White detector, developed by the NEXT (Neutrino Experiment with a Xenon TPC) collaboration, we show for the first time that an energy resolution of 1% FWHM can be achieved at 2.6 MeV, establishing the present technology as the one with the best energy resolution of all xenon detectors for ββ0ν searches. [Figure not available: see fulltext.

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

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

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)

Sensitivity of the NEXT experiment to Xe-124 double electron capture

Double electron capture by proton-rich nuclei is a second-order nuclear process analogous to double beta decay. Despite their similarities, the decay signature is quite different, potentially providing a new channel to measure the hypothesized neutrinoless mode of these decays. The Standard-Model-allowed two-neutrino double electron capture (2¿EC EC) has been predicted for a number of isotopes, but only observed in 78Kr, 130Ba and, recently, 124Xe. The sensitivity to this decay establishes a benchmark for the ultimate experimental goal, namely the potential to discover also the lepton-number-violating neutrinoless version of this process, 0¿EC EC. Here we report on the current sensitivity of the NEXT-White detector to 124Xe 2¿EC EC and on the extrapolation to NEXT-100. Using simulated data for the 2¿EC EC signal and real data from NEXT-White operated with 124Xe-depleted gas as background, we define an optimal event selection that maximizes the NEXT-White sensitivity. We estimate that, for NEXT-100 operated with xenon gas isotopically enriched with 1 kg of 124Xe and for a 5-year run, a sensitivity to the 2¿EC EC half-life of 6 × 1022 y (at 90% confidence level) or better can be reached. [Figure not available: see fulltext.