45 research outputs found

    Updated Geoneutrino Measurement with the Borexino Detector

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    Geoneutrinos are electron antineutrinos and neutrinos emitted in the radioactive decays from theEarth’s interior. Due to the intrinsic dependence of the geoneutrino flux and the heat producedin the radioactive decays, geoneutrinos contribute uniquely to our knowledge about the Earth.The main goal of neutrino geophysics is to use the obtained geoneutrino signals in estimating theabundance and distribution of the heat producing elements such as 238U, 235U, 232Th and 40K.The radiogenic heat contribution, especially the mantle contribution to the total surface heat fluxand the nature of the mantle still remain as open questions. The combination of the total geoneutrino flux (≈106cm−2s−1) and the weak interaction cross section (≈10−42 cm−2s−1) lead to hugestatistical uncertainties in the current measurements. This has made the study of geoneutrinosquite challenging and so far, only two detectors, namely KamLAND and Borexino, have measuredgeoneutrinos.The Borexino Detector located at the Laboratori Nazionali del Gran Sasso (LNGS), Italy firstobserved geoneutrinos in 2010 followed by two measurements in 2013 and 2015. The latest geoneutrino measurement included a 5.9σ evidence of geoneutrinos and the rejection of the null hypothesisof the mantle signal at a 98% C.L. The uncertainty in the latest published result is 26.2%. Thiswork concentrates on the further improvement of the geoneutrino measurement. The increasedstatistics and the optimised selection cuts used for the analysis have made it possible to reduce theuncertainty to 20.6%. An uncertainty of less than 20% can be achieved by the further optimisationof the selection cuts and needs more investigation

    Analysis Strategies for the Updated Geoneutrino Measurement with Borexino

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    Borexino, is one of the two detectors that has measured geoneutrinos, particles that carry direct information about the deep Earth. These electron antineutrinos can help us unravel details of the mantle, obtain the radiogenic heat contribution to Earth’s surface heat flux, and also give us limits to the hypothetical georeactor.Geoneutrinos are measured using the Inverse Beta Decay channel in Borexino and the latest published result in 2015 has an uncertainty of 26.2%. Thanks to the updated statistics and the various optimised selection cuts, it has been possible to reduce the uncertainty by a substantial amount. This poster will cover the details of the key improvements such as increased fiducial volume analysis, improved veto for cosmogenics, extended energy and coincidence time window, as well as a more efficient α/β discrimination technique. The highlights of the results obtained from the update will also be presented

    Borexino: Improvements of the latest geoneutrino results

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    Borexino is a 280-ton liquid scintillator detector located at the Laboratori Nazionali del Gran Sasso (LNGS), Italy and is one of the two detectors that has measured geoneutrinos so far. The unprecedented radio-purity of the scintillator, the shielding with higly purified water, and the placement of the detector at a 3800 m w.e. depth have resulted in very low background levels and has made Borexino an excellent apparatus for geoneutrino measurements. This talk will summarize the latest geoneutrino analysis with Borexino, using the data obtained from December 2007 to April 2019. Enhanced analysis techniques, such as an increased fiducial volume, improved veto for cosmogenic backgrounds, extended energy and coincidence time windows, as well as a more efficient α/β particle discrimination have been adopted in this measurement. The updated statistics and these elaborated techniques have led to more than a factor two increase in exposure and an improvement in the precision from 26.2% to 17.5%, when compared to the previous measurement in 2015. The talk will highlight the geological interpretations of the obtained results, namely, the estimation of the mantle signal by exploiting the relatively well-known lithospheric contribution, the calculation of the radiogenic heat, as well as the comparison of these results to the various predictions. Even though the results are compatible with all the Earth models, there is a 2.4σ\sigma tension with those models that predict the lowest concentration of heat-producing elements inside the mantle. Additionally, we present the upper limits for a hypothetical georeactor that might be present at different locations inside the Earth

    Recent solar and geoneutrino results from Borexino

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    Spectroscopy of geoneutrinos with Borexino

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    Borexino is a 280-ton liquid scintillator detector located at the Laboratori Nazionali del Gran Sasso (LNGS), Italy and is one of the two detectors that has measured geoneutrinos so far. The unprecedented radio-purity of the scintillator, the shielding with highly purified water, and the placement of the detector at 3800 m w.e. depth have resulted in very low background levels, making Borexino an excellent apparatus for geoneutrino measurements. This article will summarize the recent geoneutrino analysis and results with Borexino, from the period December 2007 to April 2019. The updated statistics and the optimized analysis techniques such as an increased fiducial volume and sophisticated cosmogenic vetoes, have led to more than a two-fold increase in exposure when compared to the previous measurement in 2015, resulting in a significant improvement in the precision. In addition, Borexino has also been able to reject the null hypothesis of the mantle geoneutrino signal with 99% C.L., for the first time, by exploiting the extensive knowledge of the crust surrounding the detector. This article will also include other geological interpretations of the obtained results such as the calculation of the radiogenic heat and the comparison of the results to various predictions. Additionally, upper limits for a hypothetical georeactor that might be present at different locations inside the Earth will also be discussed
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