75 research outputs found
Recommended from our members
Demonstration of the event identification capabilities of the NEXT-White detector
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. [Figure not available: see fulltext.
Recommended from our members
Radiogenic backgrounds in the NEXT double beta decay experiment
Natural radioactivity represents one of the main backgrounds in the search for neutrinoless double beta decay. Within the NEXT physics program, the radioactivity- induced backgrounds are measured with the NEXT-White detector. Data from 37.9 days of low-background operations at the Laboratorio SubterrĂĄneo de Canfranc with xenon depleted in 136Xe are analyzed to derive a total background rate of (0.84±0.02) mHz above 1000 keV. The comparison of data samples with and without the use of the radon abatement system demonstrates that the contribution of airborne-Rn is negligible. A radiogenic background model is built upon the extensive radiopurity screening campaign conducted by the NEXT collaboration. A spectral fit to this model yields the specific contributions of 60Co, 40K, 214Bi and 208Tl to the total background rate, as well as their location in the detector volumes. The results are used to evaluate the impact of the radiogenic backgrounds in the double beta decay analyses, after the application of topological cuts that reduce the total rate to (0.25±0.01) mHz. Based on the best-fit background model, the NEXT-White median sensitivity to the two-neutrino double beta decay is found to be 3.5Ï after 1 year of data taking. The background measurement in a QÎČÎȱ100 keV energy window validates the best-fit background model also for the neutrinoless double beta decay search with NEXT-100. Only one event is found, while the model expectation is (0.75±0.12) events. [Figure not available: see fulltext.]
Recommended from our members
Energy calibration of the NEXT-White detector with 1% resolution near Q ÎČÎČ 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 (ÎČÎČ0Îœ), 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 ÎČÎČ0Îœ searches. [Figure not available: see fulltext.
Relationships between quality of life and family function in caregiver
<p>Abstract</p> <p>Background</p> <p>There are caregivers who see their quality of life (QoL) impaired due to the demands of their caregiving tasks, while others manage to adapt and overcome the crises successfully. The influence of the family function in the main caregiver's situation has not been the subject of much evaluation. The aim of this study is to analyse the relationship between the functionality of the family and the QoL of caregivers of dependent relatives.</p> <p>Methods</p> <p>We conducted a cross-sectional study including 153 caregivers. Setting: Two health centers in the city of Salamanca(Spain). Caregiver variables analysed: demographic characteristics, care recipient features; family functionality (Family APGAR-Q) and QoL (Ruiz-Baca-Q) perceived by the caregiver. Five multiple regressions are performed considering global QoL and each of the four QoL dimensions as dependent variables. The Canonical Correspondence Analysis (CCA) was used to study the influence of the family function questionnaire on QoL.</p> <p>Results</p> <p>Family function is the only one of the variables evaluated that presented an association both with global QoL and with each of the four individual dimensions (p < 0.05). Using the CCA, we found that the physical and mental well-being dimensions are the ones which present a closer relationship with family functionality, while social support is the quality dimension that is least influenced by the Family APGAR-Q.</p> <p>Conclusion</p> <p>We find an association between family functionality and the caregiver's QoL. This relation holds for both the global measure of QoL and each of its four individual dimensions.</p
Electroluminescence TPCs at the thermal diffusion limit
[EN] The NEXT experiment aims at searching for the hypothetical neutrinoless double-beta decay from the 136Xe isotope using a high-purity xenon TPC. Efficient discrimination of the events through pattern recognition of the topology of primary ionisation tracks is a major requirement for the experiment. However, it is limited by the diffusion of electrons. It is known that the addition of a small fraction of a molecular gas to xenon reduces electron diffusion. On the other hand, the electroluminescence (EL) yield drops and the achievable energy resolution may be compromised. We have studied the effect of adding several molecular gases to xenon (CO2, CH4 and CF4) on the EL yield and energy resolution obtained in a small prototype of driftless gas proportional scintillation counter. We have compared our results on the scintillation characteristics (EL yield and energy resolution) with a microscopic simulation, obtaining the diffusion coefficients in those conditions as well. Accordingly, electron diffusion may be reduced from about 10 mm/ sqrt(Âż) for pure xenon down to 2.5 mm/sqrt(m) using additive concentrations of about 0.05%, 0.2% and 0.02% for CO2, CH4 and CF4, respectively. Our results show that CF4 admixtures present the highest EL yield in those conditions, but very poor energy resolution as a result of huge fluctuations observed in the EL formation. CH4 presents the best energy resolution despite the EL yield being the lowest. The results obtained with xenon admixtures are extrapolated to the operational conditions of the NEXT-100 TPC. CO2 and CH4 show potential as molecular additives in a large xenon TPC. While CO2 has some operational constraints, making it difficult to be used in a large TPC, CH4 shows the best performance and stability as molecular additive to be used in the NEXT-100 TPC, with an extrapolated energy resolution of 0.4% at 2.45 MeV for concentrations below 0.4%, which is only slightly worse than the one obtained for pure xenon. We demonstrate the possibility to have an electroluminescence TPC operating very close to the thermal diffusion limit without jeopardizing the TPC performance, if CO2 or CH4 are chosen as additives.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 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; the U.S. Department of Energy under contracts number DE-AC02-07CH11359 (Fermi National Accelerator Laboratory), DE-AC02-06CH11357 (Argonne National Laboratory), DE-FG02-13ER42020 (Texas A&M) and DE-SC0017721 (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.Henriques, CAO.; Monteiro, CMB.; Gonzalez-Diaz, D.; Azevedo, CDR.; Freitas, EDC.; Mano, RDP.; Jorge, MR.... (2019). Electroluminescence TPCs at the thermal diffusion limit. Journal of High Energy Physics (Online). 1:1-20. https://doi.org/10.1007/JHEP01(2019)027S1201NEXT collaboration, J. MartĂn-Albo et al., Sensitivity of NEXT-100 to neutrinoless double beta decay, JHEP 05 (2016) 159 [ arXiv:1511.09246 ] [ INSPIRE ].T. Brunner et al., An RF-only ion-funnel for extraction from high-pressure gases, Intern. J. Mass Spectrom. 379 (2015) 110 [ INSPIRE ].PANDAX-III collaboration, J. Galan, Microbulk MicrOMEGAs for the search of 0ÎœÎČÎČ of 136 Xe in the PandaX-III experiment, 2016 JINST 11 P04024 [ arXiv:1512.09034 ] [ INSPIRE ].D. Yu. Akimov, A.A. Burenkov, V.F. Kuzichev, V.L. Morgunov and V.N. Solovev, Low background experiments with high pressure gas scintillation proportional detector, physics/9704021 [ INSPIRE ].Yu. M. Gavrilyuk et al., A technique for searching for the 2K capture in 124 Xe with a copper proportional counter, Phys. Atom. Nucl. 78 (2015) 1563 [ INSPIRE ].D.R. Nygren, Columnar recombination: a tool for nuclear recoil directional sensitivity in a xenon-based direct detection WIMP search, J. Phys. Conf. Ser. 460 (2013) 012006 [ INSPIRE ].XENON collaboration, E. Aprile et al., First Dark Matter Search Results from the XENON1T Experiment, Phys. Rev. Lett. 119 (2017) 181301 [ arXiv:1705.06655 ] [ INSPIRE ].XENON100 collaboration, E. Aprile et al., Dark Matter Results from 225 Live Days of XENON100 Data, Phys. Rev. Lett. 109 (2012) 181301 [ arXiv:1207.5988 ] [ INSPIRE ].LUX collaboration, D.S. Akerib et al., Results from a search for dark matter in the complete LUX exposure, Phys. Rev. Lett. 118 (2017) 021303 [ arXiv:1608.07648 ] [ INSPIRE ].PandaX-II collaboration, X. Cui et al., Dark Matter Results From 54-Ton-Day Exposure of PandaX-II Experiment, Phys. Rev. Lett. 119 (2017) 181302 [ arXiv:1708.06917 ] [ INSPIRE ].EXO collaboration, J.B. Albert et al., Search for Neutrinoless Double-Beta Decay with the Upgraded EXO-200 Detector, Phys. Rev. Lett. 120 (2018) 072701 [ arXiv:1707.08707 ] [ INSPIRE ].KamLAND-Zen collaboration, A. Gando et al., Search for Majorana Neutrinos near the Inverted Mass Hierarchy Region with KamLAND-Zen, Phys. Rev. Lett. 117 (2016) 082503 [ arXiv:1605.02889 ] [ INSPIRE ].XMASS collaboration, K. Abe et al., Search for two-neutrino double electron capture on 124 Xe with the XMASS-I detector, Phys. Lett. B 759 (2016) 64 [ arXiv:1510.00754 ] [ INSPIRE ].XENON collaboration, E. Aprile et al., Search for two-neutrino double electron capture of 124 Xe with XENON100, Phys. Rev. C 95 (2017) 024605 [ arXiv:1609.03354 ] [ INSPIRE ].R. LĂŒscher et al., Search for ÎČÎČ decay in 136 Xe: new results from the Gotthard experiment, Phys. Lett. B 434 (1998) 407 [ INSPIRE ].NEXT collaboration, P. Ferrario et al., First proof of topological signature in the high pressure xenon gas TPC with electroluminescence amplification for the NEXT experiment, JHEP 01 (2016) 104 [ arXiv:1507.05902 ] [ INSPIRE ].NEXT collaboration, D. Lorca et al., Characterisation of NEXT-DEMO using xenon K α X-rays, 2014 JINST 9 P10007 [ arXiv:1407.3966 ] [ INSPIRE ].NEXT collaboration, D. GonzĂĄlez-DĂaz et al., Accurate Îł and MeV-electron track reconstruction with an ultra-low diffusion Xenon/TMA TPC at 10 atm, Nucl. Instrum. Meth. A 804 (2015) 8 [ arXiv:1504.03678 ] [ INSPIRE ].C.M.B. Monteiro et al., Secondary Scintillation Yield in Pure Xenon, 2007 JINST 2 P05001 [ physics/0702142 ] [ INSPIRE ].C.M.B. Monteiro, J.A.M. Lopes, J.F. C.A. Veloso and J.M.F. dos Santos, Secondary scintillation yield in pure argon, Phys. Lett. B 668 (2008) 167 [ INSPIRE ].E.D.C. Freitas et al., Secondary scintillation yield in high-pressure xenon gas for neutrinoless double beta decay (0ÎœÎČÎČ) search, Phys. Lett. B 684 (2010) 205 [ INSPIRE ].C.M.B. Monteiro et al., Secondary scintillation yield from gaseous micropattern electron multipliers in direct dark matter detection, Phys. Lett. B 677 (2009) 133 [ INSPIRE ].C.M.B. Monteiro, L.M.P. Fernandes, J.F. C.A. Veloso, C.A.B. Oliveira and J.M.F. dos Santos, Secondary scintillation yield from GEM and THGEM gaseous electron multipliers for direct dark matter search, Phys. Lett. B 714 (2012) 18 [ INSPIRE ].C. Balan et al., MicrOMEGAs operation in high pressure xenon: Charge and scintillation readout, 2011 JINST 6 P02006 [ arXiv:1009.2960 ] [ INSPIRE ].J.M.F. dos Santos et al., Development of portable gas proportional scintillation counters for x-ray spectrometry, X-Ray Spectrom. 30 (2001) 373.NEXT collaboration, J. Renner et al., Background rejection in NEXT using deep neural networks, 2017 JINST 12 T01004 [ arXiv:1609.06202 ] [ INSPIRE ].T. Himi et al., Emission spectra from Ar-Xe, Ar-Kr, Ar-N2, Ar-CH4, Ar-CO2 and Xe-N2 gas proportional scintillation counters, Nucl. Instrum. Meth. 205 (1983) 591.C.D.R. Azevedo et al., An homeopathic cure to pure Xenon large diffusion, 2016 JINST 11 C02007 [ arXiv:1511.07189 ] [ INSPIRE ].NEXT collaboration, C.A.O. Henriques et al., Secondary scintillation yield of xenon with sub-percent levels of CO 2 additive for rare-event detection, Phys. Lett. B 773 (2017) 663 [ arXiv:1704.01623 ] [ INSPIRE ].P.C.P.S. SimĂ”es, J.M.F. dos Santos and C.A.N. Conde, Driftless gas proportional scintillation counter pulse analysis using digital processing techniques, X Ray Spectrom. 30 (2001) 342.P.C.P.S. SimĂ”es et al., A new method for pulse analysis of driftless-gas proportional scintillation counters, Nucl. Instrum. Meth. A 505 (2003) 247.C.D.R. Azevedo et al., Microscopic simulation of xenon-based optical TPCs in the presence of molecular additives, Nucl. Instrum. Meth. A 877 (2018) 157 [ arXiv:1705.09481 ] [ INSPIRE ].L.M.P. Fernandes et al., Primary and secondary scintillation measurements in a xenon Gas Proportional Scintillation Counter, 2010 JINST 5 P09006 [Erratum ibid. 5 (2010) A12001] [ arXiv:1009.2719 ] [ INSPIRE ].C.M.B. Monteiro et al., An argon gas proportional scintillation counter with UV avalanche photodiode scintillation readout, IEEE Trans. Nucl. Sci. 48 (2001) 1081.J.A.M. Lopes et al., A xenon gas proportional scintillation counter with a UV-sensitive large-area avalanche photodiode, IEEE Trans. Nucl. Sci. 48 (2001) 312.D.F. Anderson et al., A large area gas scintillation proportional counter, Nucl. Instrum. Meth. 163 (1979) 125.Z. Kowalski et al., Fano factor implications from gas scintillation proportional counter measurements, Nucl. Instrum. Meth. A 279 (1989) 567.S.J.C. do Carmo et al., Experimental study of the Ï-values and Fano factors of gaseous xenon and Ar-Xe mixtures for X-rays, IEEE Trans. Nucl. Sci. 55 (2008) 2637.http://magboltz.web.cern.ch/magboltz/ (accessed 14.11.2016).T.H.V.T. Dias et al., Full-energy absorption of x-ray energies near the Xe L- and K-photoionization thresholds in xenon gas detectors: Simulation and experimental results, J. Appl. Phys. 82 (1997) 2742.D. Nygren, High-pressure xenon gas electroluminescent TPC for 0ÎœÎČÎČ-decay search, Nucl. Instrum. Meth. A 603 (2009) 337 [ INSPIRE ].NEXT collaboration, V. Ălvarez et al., The NEXT-100 experiment for neutrinoless double beta decay searches (Conceptual Design Report), arXiv:1106.3630 [ INSPIRE ].NEXT collaboration, V. Ălvarez et al., Operation and first results of the NEXT-DEMO prototype using a silicon photomultiplier tracking array, 2013 JINST 8 P09011 [ arXiv:1306.0471 ] [ INSPIRE ]
Combined measurement of differential and total cross sections in the HâŻââŻÎłÎł and the HâŻââŻZZ*âŻââŻ4â decay channels at s=13 TeV with the ATLAS detector
A combined measurement of differential and inclusive total cross sections of Higgs boson production is performed using 36.1 fbâ1 of 13 TeV protonâproton collision data produced by the LHC and recorded by the ATLAS detector in 2015 and 2016. Cross sections are obtained from measured Hâγγ and HâZZ*(â4â event yields, which are combined taking into account detector efficiencies, resolution, acceptances and branching fractions. The total Higgs boson production cross section is measured to be 57.0â5.9 +6.0 (stat.) â3.3 +4.0 (syst.) pb, in agreement with the Standard Model prediction. Differential cross-section measurements are presented for the Higgs boson transverse momentum distribution, Higgs boson rapidity, number of jets produced together with the Higgs boson, and the transverse momentum of the leading jet. The results from the two decay channels are found to be compatible, and their combination agrees with the Standard Model predictions
Measurement of the tÂŻtZ and tÂŻtW cross sections in proton-proton collisions at âs=13âTeV with the ATLAS detector
A measurement of the associated production of a top-quark pair (tÂŻt) with a vector boson (W, Z) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented, using 36.1ââfbâ1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. Events are selected in channels with two same- or opposite-sign leptons (electrons or muons), three leptons or four leptons, and each channel is further divided into multiple regions to maximize the sensitivity of the measurement. The tÂŻtZ and tÂŻtW production cross sections are simultaneously measured using a combined fit to all regions. The best-fit values of the production cross sections are ÏtÂŻtZ=0.95±0.08stat±0.10systâpb and ÏtÂŻtW=0.87±0.13stat±0.14systâpb in agreement with the Standard Model predictions. The measurement of the tÂŻtZ cross section is used to set constraints on effective field theory operators which modify the tÂŻtZ vertex
Search for pair production of heavy vector-like quarks decaying into high-pT W bosons and top quarks in the lepton-plus-jets final state in pp collisions at âs = 13 TeV with the ATLAS detector
A search is presented for the pair production of heavy vector-like B quarks, primarily targeting B quark decays into a W boson and a top quark. The search is based on 36.1 fb â1 of pp collisions at âs = 13 TeV recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Data are analysed in the lepton-plus-jets final state, characterised by a high-transverse-momentum isolated electron or muon, large missing transverse momentum, and multiple jets, of which at least one is b -tagged. No significant deviation from the Standard Model expectation is observed. The 95% confidence level lower limit on the B mass is 1350 GeV assuming a 100% branching ratio to Wt. In the SU(2) singlet scenario, the lower mass limit is 1170 GeV. This search is also sensitive to a heavy vector-like B quark decaying into other final states (Zb and Hb ) and thus mass limits on B production are set as a function of the decay branching ratios. The 100% branching ratio limits are found to be also applicable to heavy vector-like X production, with charge +5/3, that decay into Wt
Observation of electroweak production of two jets and a Z-boson pair
Electroweak symmetry breaking explains the origin of the masses of elementary particles through their interactions with the Higgs field. Besides the measurements of the Higgs boson properties, the study of the scattering of massive vector bosons with spin 1 allows the nature of electroweak symmetry breaking to be probed. Among all processes related to vector-boson scattering, the electroweak production of two jets and a Z-boson pair is a rare and important one. Here we report the observation of this process from protonâproton collision data corresponding to an integrated luminosity of 139âfbâ1 recorded at a centre-of-mass energy of 13âTeV with the ATLAS detector at the Large Hadron Collider. We consider two different final states originating from the decays of the Z-boson pair: one containing four charged leptons and another containing two charged leptons and two neutrinos. The hypothesis of no electroweak production is rejected with a statistical significance of 5.7Ï, and the measured cross-section for electroweak production is consistent with the Standard Model prediction. In addition, we report cross-sections for inclusive production of a Z-boson pair and two jets for the two final states
- âŠ