Geo-neutrinos and Earth's interior

The deepest hole that has ever been dug is about 12 km deep. Geochemists analyze samples from the Earth's crust and from the top of the mantle. Seismology can reconstruct the density profile throughout all Earth, but not its composition. In this respect, our planet is mainly unexplored. Geo-neutrinos, the antineutrinos from the progenies of U, Th and K40 decays in the Earth, bring to the surface information from the whole planet, concerning its content of natural radioactive elements. Their detection can shed light on the sources of the terrestrial heat flow, on the present composition, and on the origins of the Earth. Geo-neutrinos represent a new probe of our planet, which can be exploited as a consequence of two fundamental advances that occurred in the last few years: the development of extremely low background neutrino detectors and the progress on understanding neutrino propagation. We review the status and the prospects of the field.Comment: 56 pages in RMP ReVTeX format, 36 figures. A few typos corrected and a few minor points changed: resubmitted only to match the final version accepted for publication by Physics Report

Geo-neutrinos: a new probe of Earth's interior

In preparation to the experimental results which will be available in the future, we study geo-neutrino production for different models of mantle convection and composition. By using global mass balance for the Bulk Silicate Earth, the predicted flux contribution from distant sources in the crust and in the mantle is fixed within a total uncertainty of +-15%. We also discuss regional effects, provided by subducting slabs or plumes near the detector. In four years a five-kton detector operating at a site relatively far from nuclear power plants can achieve measurements of the geo-neutrino signal accurate to within +-5%. It will provide a crucial test of the Bulk Silicate Earth and a direct estimate of the radiogenic contribution to terrestrial heat.Comment: 19 pages, 6 tables, 7 figures; accepted for publication in Earth and Planetary Science Letter

Filling the gap between education and industry: evidence-based methods for introducing undergraduate students to HPC

Educational institutions provide in most cases basic theoretical background covering several computational science topics, however High Performance Computing (HPC) and Parallel and Distributed Computing (PDC) markets require specialized technical profiles. Even the most skilled students are often not prepared to face production HPC applications of thousands of lines nor complex computational frameworks from other disciplines nor heterogeneous multinode machines accessed by hundreds of users. In this paper, we offer an educational package for filling this gap. Leveraging the 4-years experience of the Student Cluster Competition, we present our educational journey together with the lessons learned and the outcomes of our methodology. We show how, in a time span of a semester and an affordable budget, a university can implement an educational package preparing pupils for starting competitive professional careers. Our findings also highlight that 78% of the students exposed to our methods remain within the HPC high-education, research or industry.The authors of this paper and the participants in the SCC have been supported by the European Community’s Seventh Framework Programme [FP7/2007-2013] and Horizon 2020 under the Mont-Blanc projects, grant agreements n. 288777, 610402 and 671697; the HPC Advisory Council; the Facultat d’Informàtica de Barcelona – Universitat Politècnica de Catalunya; Arm Ltd.; Cavium Inc.; E4 Computer Engineering. We warmly thank Luna Backes Drault for her unconditioned dedication to the SCC cause in the early days and the pizzeria 7bello in Frankfurt for always having a table and a smile for us.SiPreprin

Source of Variation of Linear Type Traits Evaluated on Italian Heavy Draught Horse Breed

The aim of this study was to analyze the non-genetic fixed effects affecting 14 linear type traits and an overall score recorded on 4,385 Italian Heavy Draught Horse adults (IHDH; 3,772 females and 613 males) scored by 29 classifiers in 20 years of evaluation (i.e. 1992-2011). Animals were scored with a 9 point scale system (1-5 including half points) at about 3 years of age. Data were analyzed by ANOVA to evaluate the magnitude of three non-genetic fixed effects: stud-year of evaluation-classifier (SYC; 1,325 levels), sex (2 levels), age at evaluation (AC; 5 classes, i.e., ≤27, 28, 29-32, 33-47, and ≥48 months of age). The R-square of model for all analyzed traits ranged from 0.38 to 0.57, with lower values for fore feet and greater values for frame size. The SYC resulted the effect of greater magnitude and in all traits adsorbed a significant amount of variation. Sex differentiated mainly frame size, fleshiness, bone incidence, fore diameters and upper line direction, indicating a significant aspects between males and females as regard the meat production characteristics of the breed. The AC influenced significantly frame size, fleshiness, thorax depth, fore diameters, rear diameters and the overall score. It is concluded that all potential source of variation need to be taken into account in the analysis of data from linear type evaluation of adult IHDH

Geo-Neutrinos: from Theory to the KamLAND Results

Earth shines in antineutrinos produced from long-lived radioactive elements: detection of this signal can provide a direct test of the Bulk Silicate Earth (BSE) model and fix the radiogenic contribution to the terrestrial heat flow. In this paper we present a systematic approach to geo-neutrino production based on global mass balance, supplemented by a detailed geochemical and geophysical study of the region near the detector, in order to build theoretical constraints on the expected signal. We show that the prediction is weakly dependent on mantle modeling while it requires a good description of the crust composition in the region of the detector site. In 2005 the KamLAND experiment proved that the technique for exploiting geo-neutrinos in the investigation of the Earth's interior is now available. After performing an analysis of KamLAND data which includes recent high precision measurements of the 13C(α, n)16O cross section, we discuss the potential of future experiments for assessing the amount of uranium and thorium in different reservoirs (crust, mantle and core) of the Earth

KamLAND results and the radiogenic terrestrial heat

We find that recent results from the KamLAND collaboration on geologically produced antineutrinos, N(U+Th) = 28+16-15 events, correspond to a radiogenic heat production from Uranium and Thorium decay chains H(U+Th) = 38+35-33 TW. The 99% confidence limit on the geo-neutrino signal translates into the upper bound H(U+Th) < 162 TW, which is much weaker than that claimed by KamLAND, H(U+Th) < 60 TW, based on a too narrow class of geological models. We also performed an analysis of KamLAND data including recent high precision measurements of the C13(\alpha,n)O16 cross section. The result, N(U+Th) = 31+14-13, corroborates the evidence (approx 2.5\sigma) for geo-neutrinos in KamLAND data.Comment: 7 pages (RevTex), 2 figures. Minor changes that match the version accepted for publication on Phys. Lett.

Expected geoneutrino signal at JUNO

Constraints on the Earth's composition and on its radiogenic energy budget come from the detection of geoneutrinos. The KamLAND and Borexino experiments recently reported the geoneutrino flux, which reflects the amount and distribution of U and Th inside the Earth. The KamLAND and Borexino experiments recently reported the geoneutrino flux, which reflects the amount and distribution of U and Th inside the Earth. The JUNO neutrino experiment, designed as a 20 kton liquid scintillator detector, will be built in an underground laboratory in South China about 53 km from the Yangjiang and Taishan nuclear power plants. Given the large detector mass and the intense reactor antineutrino flux, JUNO aims to collect high statistics antineutrino signals from reactors but also to address the challenge of discriminating the geoneutrino signal from the reactor background.The predicted geoneutrino signal at JUNO is 39.7 $^{+6.5}_{-5.2}$ TNU, based on the existing reference Earth model, with the dominant source of uncertainty coming from the modeling of the compositional variability in the local upper crust that surrounds (out to $\sim$ 500 km) the detector. A special focus is dedicated to the 6{\deg} x 4{\deg} Local Crust surrounding the detector which is estimated to contribute for the 44% of the signal. On the base of a worldwide reference model for reactor antineutrinos, the ratio between reactor antineutrino and geoneutrino signals in the geoneutrino energy window is estimated to be 0.7 considering reactors operating in year 2013 and reaches a value of 8.9 by adding the contribution of the future nuclear power plants. In order to extract useful information about the mantle's composition, a refinement of the abundance and distribution of U and Th in the Local Crust is required, with particular attention to the geochemical characterization of the accessible upper crust.Comment: Slight changes and improvements in the text,22 pages, 4 Figures, 3 Tables. Prog. in Earth and Planet. Sci. (2015

Regional study of the Archean to Proterozoic crust at the Sudbury Neutrino Observatory (SNO+), Ontario: Predicting the geoneutrino flux

The SNO+ detector, a new kiloton scale liquid scintillator detector capable of recording geoneutrino events, will define the strength of the Earth radiogenic heat. A detailed 3-D model of the regional crust, centered at SNO+ and based on compiled geological, geophysical and geochemical information, was used to characterize the physical and chemical attributes of crust and assign uncertainties to its structure. Monte Carlo simulations were used to predict the U and Th abundances and uncertainties in crustal lithologies and to model the regional crustal geoneutrino signal originating from the at SNO+

Exploring atmospheric radon with airborne gamma-ray spectroscopy

$^{222}$Rn is a noble radioactive gas produced along the $^{238}$U decay chain, which is present in the majority of soils and rocks. As $^{222}$Rn is the most relevant source of natural background radiation, understanding its distribution in the environment is of great concern for investigating the health impacts of low-level radioactivity and for supporting regulation of human exposure to ionizing radiation in modern society. At the same time, $^{222}$Rn is a widespread atmospheric tracer whose spatial distribution is generally used as a proxy for climate and pollution studies. Airborne gamma-ray spectroscopy (AGRS) always treated $^{222}$Rn as a source of background since it affects the indirect estimate of equivalent $^{238}$U concentration. In this work the AGRS method is used for the first time for quantifying the presence of $^{222}$Rn in the atmosphere and assessing its vertical profile. High statistics radiometric data acquired during an offshore survey are fitted as a superposition of a constant component due to the experimental setup background radioactivity plus a height dependent contribution due to cosmic radiation and atmospheric $^{222}$Rn. The refined statistical analysis provides not only a conclusive evidence of AGRS $^{222}$Rn detection but also a (0.96 $\pm$ 0.07) Bq/m$^{3}$ $^{222}$Rn concentration and a (1318 $\pm$ 22) m atmospheric layer depth fully compatible with literature data.Comment: 17 pages, 8 figures, 2 table