Ľudovít Turčan, Robert Klobucký: Denníky sociológov I. Alexander Hirner. 1953–1955

The Jiangmen Underground Neutrino Observatory (JUNO) is a next-generation neutrino experiment under construction in China expected to be completed in 2022. As the main goal it aims to determine the neutrino mass ordering with 3-4 $\sigma$ significance using a 20 kton liquid scintillator detector. It will measure the oscillated energy spectrum of electron anti-neutrinos from two nuclear power plants at about 53 km baseline with an unprecedented energy resolution of 3% at 1 MeV. A requirement of the JUNO experiment is the knowledge of the energy non-linearity of the detector with a sub-percent precision. As the light yield of the liquid scintillator is not fully linear to the energy of the detected particle and dependent on the particle type, a model for this light yield is presented in this paper. Based on an energy non-linearity model of electrons, this article provides the conversion to the more complex energy response of positrons and gammas. This conversion uses a fast and simple algorithm to calculate the spectrum of secondary electrons generated by a gamma, which is introduced here and made open access to potential users. It is also discussed how the positron non-linearity can be obtained from the detector calibration with gamma sources using the results presented in this article.Comment: 19 pages and 12 figures, submitted to Journal of Instrumentatio

Test of the electron stability with the Borexino detector

Despite the fact that the electric charge conservation law is confirmed by many experiments, search for its possible violation remains a way of searching for physics beyond the Standard Model. Experimental searches for the electric charge non-conservation mainly consider electron decays into neutral particles. The Borexino experiment is an excellent tool for the electron decay search due to the highest radiopurity among all the existing experiments, large detector mass, and good sensitivity at low energies. The process considered in this study is a decay into a photon and a neutrino, for which a new lower limit on the electron lifetime is obtained. This is the best electron lifetime limit up to date, exceeding the previous one obtained at the Borexino prototype at two orders of magnitude

Sensitivity to neutrinos from the solar CNO cycle in Borexino

Neutrinos emitted in the carbon, nitrogen, oxygen (CNO) fusion cycle in the Sun are a sub-dominant, yet crucial component of solar neutrinos whose flux has not been measured yet. The Borexino experiment at the Laboratori Nazionali del Gran Sasso (Italy) has a unique opportunity to detect them directly thanks to the detector’s radiopurity and the precise understanding of the detector backgrounds. We discuss the sensitivity of Borexino to CNO neutrinos, which is based on the strategies we adopted to constrain the rates of the two most relevant background sources, $pep$ neutrinos from the solar pp-chain and $^{210}$Bi beta decays originating in the intrinsic contamination of the liquid scintillator with $^{210}$Pb. Assuming the CNO flux predicted by the high-metallicity Standard Solar Model and an exposure of 1000 days $\times$ 71.3 t, Borexino has a median sensitivity to CNO neutrino higher than 3 $\sigma$. With the same hypothesis the expected experimental uncertainty on the CNO neutrino flux is 23%, provided the uncertainty on the independent estimate of the $^{210}\text {Bi}$ interaction rate is 1.5 $\hbox {cpd}/100~\hbox {ton}$. Finally, we evaluated the expected uncertainty of the C and N abundances and the expected discrimination significance between the high and low metallicity Standard Solar Models (HZ and LZ) with future more precise measurement of the CNO solar neutrino flux

Experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun

International audienceFor most of their existence, stars are fuelled by the fusion of hydrogen into helium. Fusion proceeds via two processes that are well understood theoretically: the proton–proton (pp) chain and the carbon–nitrogen–oxygen (CNO) cycle. Neutrinos that are emitted along such fusion processes in the solar core are the only direct probe of the deep interior of the Sun. A complete spectroscopic study of neutrinos from the pp chain, which produces about 99 per cent of the solar energy, has been performed previously; however, there has been no reported experimental evidence of the CNO cycle. Here we report the direct observation, with a high statistical significance, of neutrinos produced in the CNO cycle in the Sun. This experimental evidence was obtained using the highly radiopure, large-volume, liquid-scintillator detector of Borexino, an experiment located at the underground Laboratori Nazionali del Gran Sasso in Italy. The main experimental challenge was to identify the excess signal—only a few counts per day above the background per 100 tonnes of target—that is attributed to interactions of the CNO neutrinos. Advances in the thermal stabilization of the detector over the last five years enabled us to develop a method to constrain the rate of bismuth-210 contaminating the scintillator. In the CNO cycle, the fusion of hydrogen is catalysed by carbon, nitrogen and oxygen, and so its rate—as well as the flux of emitted CNO neutrinos—depends directly on the abundance of these elements in the solar core. This result therefore paves the way towards a direct measurement of the solar metallicity using CNO neutrinos. Our findings quantify the relative contribution of CNO fusion in the Sun to be of the order of 1 per cent; however, in massive stars, this is the dominant process of energy production. This work provides experimental evidence of the primary mechanism for the stellar conversion of hydrogen into helium in the Universe

First Simultaneous Precision Spectroscopy of pppp, 7^7Be, and peppep Solar Neutrinos with Borexino Phase-II

We present the first simultaneous measurement of the interaction rates of $pp$, $^7$Be, and $pep$ solar neutrinos performed with a global fit to the Borexino data in an extended energy range (0.19-2.93)$\,$MeV. This result was obtained by analyzing 1291.51$\,$days of Borexino Phase-II data, collected between December 2011 and May 2016 after an extensive scintillator purification campaign. We find: rate($pp$)$\,$=$\,$$134$$\,$$\pm$$\,$$10$$\,$($stat$)$\,$$^{\rm +6}_{\rm -10}$$\,$($sys$)$\,$cpd/100$\,$t, rate($^7$Be)$\,$=$\,$$48.3$$\,$$\pm$$\,$$1.1$$\,$($stat$)$\,$$^{\rm +0.4}_{\rm -0.7}$$\,$($sys$)$\,$cpd/100$\,$t, and rate($pep$)$\,$=$\,$$2.43$$\pm$$\,$$0.36$$\,$($stat$)$^{+0.15}_{-0.22}$$\,$($sys$)$\,$cpd/100$\,$t. These numbers are in agreement with and improve the precision of our previous measurements. In particular, the interaction rate of $^7$Be $\nu$'s is measured with an unprecedented precision of 2.7%, showing that discriminating between the high and low metallicity solar models is now largely dominated by theoretical uncertainties. The absence of $pep$ neutrinos is rejected for the first time at more than 5$\,$$\sigma$. An upper limit of $8.1$$\,$cpd/100$\,$t (95%$\,$C.L.) on the CNO neutrino rate is obtained by setting an additional constraint on the ratio between the $pp$ and $pep$ neutrino rates in the fit. This limit has the same significance as that obtained by the Borexino Phase-I (currently providing the tightest bound on this component), but is obtained by applying a less stringent constraint on the $pep$ $\nu$ flux

Simultaneous precision spectroscopy of p p , Be 7 , and p e p solar neutrinos with Borexino Phase-II

We present the simultaneous measurement of the interaction rates Rpp, RBe, Rpep of pp, 7Be, and pep solar neutrinos performed with a global fit to the Borexino data in an extended energy range (0.19–2.93) MeV with particular attention to details of the analysis methods. This result was obtained by analyzing 1291.51 days of Borexino Phase-II data, collected after an extensive scintillator purification campaign. Using counts per day (cpd)/100 ton as unit, we find Rpp=134±10(stat)+6−10(sys), RBe=48.3±1.1(stat)+0.4−0.7(sys); and RHZpep=2.43±0.36(stat)+0.15−0.22(sys) assuming the interaction rate RCNO of CNO-cycle (Carbon, Nitrogen, Oxigen) solar neutrinos according to the prediction of the high metallicity standard solar model, and RLZpep=2.65±0.36(stat)+0.15−0.24(sys) according to that of the low metallicity model. An upper limit RCNO<8.1 cpd/100 ton (95% C.L.) is obtained by setting in the fit a constraint on the ratio Rpp/Rpep (47.7±0.8 cpd/100 ton or 47.5±0.8cpd/100 ton according to the high or low metallicity hypothesis)

Constraints on flavor-diagonal non-standard neutrino interactions from Borexino Phase-II

International audienceThe Borexino detector measures solar neutrino fluxes via neutrino-electron elastic scattering. Observed spectra are determined by the solar-ν$_{e}$ survival probability P$_{ee}$(E), and the chiral couplings of the neutrino and electron. Some theories of physics beyond the Standard Model postulate the existence of Non-Standard Interactions (NSI’s) which modify the chiral couplings and P$_{ee}$(E). In this paper, we search for such NSI’s, in particular, flavor-diagonal neutral current interactions that modify the ν$_{e}$e and ν$_{τ}$e couplings using Borexino Phase II data. Standard Solar Model predictions of the solar neutrino fluxes for both high- and low-metallicity assumptions are considered. No indication of new physics is found at the level of sensitivity of the detector and constraints on the parameters of the NSI’s are placed. In addition, with the same dataset the value of sin$^{2}$θ$_{W}$ is obtained with a precision comparable to that achieved in reactor antineutrino experiments[graphic not available: see fulltext]

Comprehensive geoneutrino analysis with Borexino

open112siThis paper presents a comprehensive geoneutrino measurement using the Borexino detector, located at Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The analysis is the result of 3262.74 days of data between December 2007 and April 2019. The paper describes improved analysis techniques and optimized data selection, which includes enlarged fiducial volume and sophisticated cosmogenic veto. The reported exposure of (1.29±0.05)×1032 protons ×year represents an increase by a factor of two over a previous Borexino analysis reported in 2015. By observing 52.6-8.6+9.4(stat)-2.1+2.7(sys) geoneutrinos (68% interval) from U238 and Th232, a geoneutrino signal of 47.0-7.7+8.4(stat)-1.9+2.4(sys) TNU with -17.2+18.3% total precision was obtained. This result assumes the same Th/U mass ratio as found in chondritic CI meteorites but compatible results were found when contributions from U238 and Th232 were both fit as free parameters. Antineutrino background from reactors is fit unconstrained and found compatible with the expectations. The null-hypothesis of observing a geoneutrino signal from the mantle is excluded at a 99.0% C.L. when exploiting detailed knowledge of the local crust near the experimental site. Measured mantle signal of 21.2-9.0+9.5(stat)-0.9+1.1(sys) TNU corresponds to the production of a radiogenic heat of 24.6-10.4+11.1 TW (68% interval) from U238 and Th232 in the mantle. Assuming 18% contribution of K40 in the mantle and 8.1-1.4+1.9 TW of total radiogenic heat of the lithosphere, the Borexino estimate of the total radiogenic heat of the Earth is 38.2-12.7+13.6 TW, which corresponds to the convective Urey ratio of 0.78-0.28+0.41. These values are compatible with different geological predictions, however there is a ∼2.4σ tension with those Earth models which predict the lowest concentration of heat-producing elements in the mantle. In addition, by constraining the number of expected reactor antineutrino events, the existence of a hypothetical georeactor at the center of the Earth having power greater than 2.4 TW is excluded at 95% C.L. Particular attention is given to the description of all analysis details which should be of interest for the next generation of geoneutrino measurements using liquid scintillator detectors.openAgostini M.; Altenmuller K.; Appel S.; Atroshchenko V.; Bagdasarian Z.; Basilico D.; Bellini G.; Benziger J.; Bick D.; Bonfini G.; Bravo D.; Caccianiga B.; Calaprice F.; Caminata A.; Cappelli L.; Cavalcante P.; Cavanna F.; Chepurnov A.; Choi K.; D'Angelo D.; Davini S.; Derbin A.; Di Giacinto A.; Di Marcello V.; Ding X.F.; Di Ludovico A.; Di Noto L.; Drachnev I.; Fiorentini G.; Formozov A.; Franco D.; Gabriele F.; Galbiati C.; Gschwender M.; Ghiano C.; Giammarchi M.; Goretti A.; Gromov M.; Guffanti D.; Hagner C.; Hungerford E.; Ianni A.; Ianni A.; Jany A.; Jeschke D.; Kumaran S.; Kobychev V.; Korga G.; Lachenmaier T.; Lasserre T.; Laubenstein M.; Litvinovich E.; Lombardi P.; Lomskaya I.; Ludhova L.; Lukyanchenko G.; Lukyanchenko L.; Machulin I.; Mantovani F.; Manuzio G.; Marcocci S.; Maricic J.; Martyn J.; Meroni E.; Meyer M.; Miramonti L.; Misiaszek M.; Montuschi M.; Muratova V.; Neumair B.; Nieslony M.; Oberauer L.; Onillon A.; Orekhov V.; Ortica F.; Pallavicini M.; Papp L.; Penek O.; Pietrofaccia L.; Pilipenko N.; Pocar A.; Raikov G.; Ranalli M.T.; Ranucci G.; Razeto A.; Re A.; Redchuk M.; Ricci B.; Romani A.; Rossi N.; Rottenanger S.; Schonert S.; Semenov D.; Skorokhvatov M.; Smirnov O.; Sotnikov A.; Strati V.; Suvorov Y.; Tartaglia R.; Testera G.; Thurn J.; Unzhakov E.; Vishneva A.; Vivier M.; Vogelaar R.B.; Von Feilitzsch F.; Wojcik M.; Wurm M.; Zaimidoroga O.; Zavatarelli S.; Zuber K.; Zuzel G.Agostini, M.; Altenmuller, K.; Appel, S.; Atroshchenko, V.; Bagdasarian, Z.; Basilico, D.; Bellini, G.; Benziger, J.; Bick, D.; Bonfini, G.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Cappelli, L.; Cavalcante, P.; Cavanna, F.; Chepurnov, A.; Choi, K.; D'Angelo, D.; Davini, S.; Derbin, A.; Di Giacinto, A.; Di Marcello, V.; Ding, X. F.; Di Ludovico, A.; Di Noto, L.; Drachnev, I.; Fiorentini, G.; Formozov, A.; Franco, D.; Gabriele, F.; Galbiati, C.; Gschwender, M.; Ghiano, C.; Giammarchi, M.; Goretti, A.; Gromov, M.; Guffanti, D.; Hagner, C.; Hungerford, E.; Ianni, A.; Ianni, A.; Jany, A.; Jeschke, D.; Kumaran, S.; Kobychev, V.; Korga, G.; Lachenmaier, T.; Lasserre, T.; Laubenstein, M.; Litvinovich, E.; Lombardi, P.; Lomskaya, I.; Ludhova, L.; Lukyanchenko, G.; Lukyanchenko, L.; Machulin, I.; Mantovani, F.; Manuzio, G.; Marcocci, S.; Maricic, J.; Martyn, J.; Meroni, E.; Meyer, M.; Miramonti, L.; Misiaszek, M.; Montuschi, M.; Muratova, V.; Neumair, B.; Nieslony, M.; Oberauer, L.; Onillon, A.; Orekhov, V.; Ortica, F.; Pallavicini, M.; Papp, L.; Penek, O.; Pietrofaccia, L.; Pilipenko, N.; Pocar, A.; Raikov, G.; Ranalli, M. T.; Ranucci, G.; Razeto, A.; Re, A.; Redchuk, M.; Ricci, B.; Romani, A.; Rossi, N.; Rottenanger, S.; Schonert, S.; Semenov, D.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Strati, V.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Thurn, J.; Unzhakov, E.; Vishneva, A.; Vivier, M.; Vogelaar, R. B.; Von Feilitzsch, F.; Wojcik, M.; Wurm, M.; Zaimidoroga, O.; Zavatarelli, S.; Zuber, K.; Zuzel, G