DOCSLIB.ORG

Partial Radiogenic Heat Model for Earth Revealed by Geoneutrino Measurements

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Partial Radiogenic Heat Model for Earth Revealed by Geoneutrino Measurements ARTICLES PUBLISHED ONLINE: 17 JULY 2011 | DOI: 10.1038/NGEO1205 Partial radiogenic heat model for Earth revealed by geoneutrino measurements The KamLAND Collaboration* The Earth has cooled since its formation, yet the decay of radiogenic isotopes, and in particular uranium, thorium and potassium, in the planet’s interior provides a continuing heat source. The current total heat flux from the Earth to space is 44:2 ± 1:0 TW, but the relative contributions from residual primordial heat and radiogenic decay remain uncertain. However, radiogenic decay can be estimated from the flux of geoneutrinos, electrically neutral particles that are emitted during radioactive decay and can pass through the Earth virtually unaffected. Here we combine precise measurements of the geoneutrino flux from the Kamioka Liquid-Scintillator Antineutrino Detector, Japan, with existing measurements from the C8:8 Borexino detector, Italy. We find that decay of uranium-238 and thorium-232 together contribute 20:0−8:6 TW to Earth’s heat flux. The neutrinos emitted from the decay of potassium-40 are below the limits of detection in our experiments, but are known to contribute 4 TW. Taken together, our observations indicate that heat from radioactive decay contributes about half of Earth’s total heat flux. We therefore conclude that Earth’s primordial heat supply has not yet been exhausted. he Kamioka Liquid-Scintillator Antineutrino Detector mantle, outer core and inner core. Although the mechanical (KamLAND) Collaboration reported the results of the first properties and bulk composition of the shells are well established, Tstudy of electron antineutrinos (νe s) produced within the their detailed composition, including the abundances of radiogenic Earth in 2005 (ref. 1). The KamLAND data indicated an excess species, remains uncertain. of the νe flux at energies in the range consistent with the decay Since the model assumptions are not well grounded, the chains of 238U and 232Th. The rate was consistent with geophysical predictions have large uncertainties. The bulk silicate Earth (BSE) expectations for heavy-element concentrations throughout the model of ref. 5, for example, assumes that the primordial Earth Earth's interior. The statistical significance improved as more data was formed from accretion of matter from the same nebula were obtained2. Recently, the Borexino Collaboration at Gran Sasso that formed the sun and the rest of the planets, and that the reported an excess of events they attribute to geoneutrinos3. While BSE abundances of refractory lithophile elements such as U and Borexino convincingly confirms the KamLAND excess, neither Th can be determined by a combination of measured elemental result is precise enough to provide much guidance for geophysical abundances of chondritic meteorites and mantle peridotites. The models. In this paper we present more recent KamLAND results composition deduced from this model results in a radiogenic heat that begin to constrain the models. production of 8 TW from the 238U decay chain, 8 TW from the The present analysis is possible because of the recently improved 232Th decay chain and 4 TW from 40K (ref. 6). In this model, sensitivity to geoneutrinos in the KamLAND experiment. The the radiogenic heat contribution is nearly half of the Earth's KamLAND geoneutrino background is dominated by νe s from total heat flow (44:2 ± 1:0 TW, ref. 7; see also Supplementary commercial nuclear reactors and the 13C(α;n)16O reaction initiated Note S1). Clearly, quantitative information about the radiogenic, by the decay of radioactive contaminants in the detector. In recent heat-producing elements is essential for establishing the energy years the reactor νe flux, which is outside the control of the budget, which in turn is key to understanding the Earth's experiment, was significantly reduced2 because of an extended formation and evolution. shutdown of the Kashiwazaki–Kariwa nuclear power station following an earthquake in July 2007. In the meantime, at great Geoneutrino flux effort, the purity of the KamLAND scintillator was improved, The Earth is nearly transparent to neutrinos because they interact eliminating most of the 210Pb that feeds the decay chain responsible only through the weak force. Geoneutrinos are a unique, direct for the production of α-particles from 210Po decay. The background window into the interior of the planet. Accurately mapping from the 13C(α;n)16O reaction went down by a factor of ∼20. neutrino sources inside the Earth by measuring geoneutrino fluxes The measurement presented here is based on data collected at the surface is an inverse problem requiring multiple detection between 9 March 2002 and 4 November 2009, and includes the sites. The prospects for multisite measurements have been discussed 1,2 data used in our previous publications . The total exposure to νe in refs 4,8, and an analysis of the likely sensitivity of such is (3:49±0:07)×1032 target proton years, a fivefold increase from measurements was discussed in ref. 9. For the present work, which the first KamLAND report1. The expected signal in one geophysical has limited statistics, a simple BSE-inspired reference model4 for the model4 increases from 19 events to 106 events. radiogenic material distribution is employed. The model assumes that U or Th is present in the crust and mantle but not in the Earth composition model core. The effects of radiogenic material in the local geology of Analyses of seismic waves indicate a shell structure for the Earth's Kamioka are carefully assessed but account for less than 10% of interior, conventionally denoted as crust, upper mantle, lower the total expected flux. *A full list of authors and their affiliations appears at the end of the paper. NATURE GEOSCIENCE j VOL 4 j SEPTEMBER 2011 j www.nature.com/naturegeoscience 647 © 2011 Macmillan Publishers Limited. All rights reserved. ARTICLES NATURE GEOSCIENCE DOI: 10.1038/NGEO1205 a The differential geoneutrino flux at a position r is determined 160 0 0 Best–fit reactor ν from the isotopic abundances ai(r ) at the location of the sources, r , e 140 KamLAND data Accidental isotopes Z 0 0 0 120 d8(Eν ;r) X dni(Eν ) 0 ai(r )ρ(r )P(Eν ;jr−r j) D A d3r (1) 100 i j − 0j2 dEν i dEν ⊕ 4π r r 80 60 13C(α, n)16O where the integration extends over the Earth's volume, Ai is the Best–fit geo ν Events/0.2 MeV e 40 ν decay rate per unit mass, dni(Eν )=dEν is the νe energy spectrum for Best–fit reactor e+ background ν 0 20 + best–fit geo e each mode of decay, ai(r ) is in units of isotope mass per unit rock 0 0 0 mass, ρ(r ) is the rock density and P(Eν ;jr−r j) is the νe `survival' 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 probability due to the phenomenon of oscillation after travelling a E (MeV) 0 p distance jr−r j. For the present purpose, the νe survival probability b Data–background–best–fit reactor ν is well approximated by the two-flavour oscillation formula, 40 e ν Reference geo e 2 T 2U T U 20 2 2 1:271m21 eV L m P(Eν ;L) ' 1−sin 2θ12 sin (2) 0 Eν TMeVU Events/0.2 MeV 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 where L D jr − r0j. `Matter effects' on neutrino oscillations10 E (MeV) are expected to change equation (2) by about 1%, which is p negligible compared with the statistical uncertainty. The oscillation c 100 2 2 80 parameters 1m21 and sin 2θ12 are determined with substantial Selection efficiency ν accuracy by a combined statistical analysis with KamLAND's 60 for geo e measurement of ν s produced at nuclear reactors and data from e Efficiency (%) 40 solar-neutrino experiments (assuming charge–parity–time (CPT) 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 10 symmetry ), and are given in the next section. Given the size of the Ep (MeV) Earth and the values of the neutrino oscillation parameters, for the energy range of detectable geoneutrinos the second sine function Figure 1 j Prompt energy spectrum and event selection efficiency. in equation (2) is well averaged over the volume of the Earth, giving a, Prompt energy spectrum of low-energy νe s in KamLAND. The 2 P(Eν ;L)'1−0:5sin 2θ12 to an excellent approximation. histograms indicate the backgrounds, whereas the best fit (including geoneutrinos) is shown in blue. b, Background-subtracted energy spectrum. Geoneutrino detection The blue shaded spectrum is the expectation from the reference model, KamLAND is located under Mount Ikenoyama (36:42◦ N, consisting of contributions from U (dashed curve) and Th (dotted curve). c, 137:31◦ E), near the town of Kamioka, Japan. The underground Energy dependence of the geoneutrino event selection efficiency averaged site provides an effective overburden of 2,700 m water equivalent, over the data-taking period. Statistical uncertainties are shown for the data reducing the cosmic-ray-induced atmospheric muon flux to in a, and uncertainties on the background estimation are added in b. −2 −1 5:37 ± 0:41 m h (ref. 11). The νe s are detected in 1 kt of 2 D liquid scintillator (LS) through the inverse β-decay reaction, Taking the neutrino oscillation parameter values 1m21 C ! C C C0:19 −5 2 2 νe p e n, with a 1.8 MeV neutrino energy threshold. This 7:50−0:20 × 10 eV and sin 2θ12 D 0:84 ± 0:03 from the fit to the 238 threshold cuts off much of the geoneutrino signal from the U data discussed below, the expected number of reactor νe events 232 40 and Th decay chains and renders the detector insensitive to K in the geoneutrino energy region (defined as 0:9 MeV < Ep < (other unobserved isotopes such as 235U contribute negligibly to 2:6 MeV) is 484:7 ± 26:5, including a small contribution from the the heating).
Load more

Recommended publications
  • Updated Geoneutrino Measurement with Borexino
    UPDATED GEONEUTRINO MEASUREMENT WITH BOREXINO LIVIA LUDHOVA FOR BOREXINO COLLABORATION IKP-2, FORSCHUNGSZENTRUM JÜLICH AND RWTH AACHEN UNIVERSITY, GERMANY SEPTEMBER 10TH, 2019 TAUP 2019, TOYAMA, JAPAN OUTLINE (OR WHERE IS THIS ENERGY COMING FROM?) • What are geoneutrinos and why to study them • Expected geoneutrino signal at LNGS (Italy) • Borexino and antineutrino detection • Borexino geoneutrino measurement: fresh new results • Geological interpretation EARTH’S HEAT BUDGET Radiogenic heat & Integrated surface heat flux: Geoneutrinos can help! Htot = 47 + 2 TW Lithosphere Mantle Heat production in lithosphere “well” known Big uncertainty Mantle cooling 7 - 9 TW Heat production in mantle 1 – 27 TW 4 – 27 TW Core cooling 9 – 17 TW Core cooling Mantle cooling Geoneutrinos: antineutrinos/neutrinos from the decays of long-lived radioactive isotopes naturally present in the Earth 238U (99.2739% of natural U) à 206Pb + 8 α + 8 e- + 6 anti-neutrinos + 51.7 MeV 232Th à 208Pb + 6 α + 4 e- + 4 anti-neutrinos + 42.8 MeV 235U (0.7205% of natural U) à 207Pb + 7 α + 4 e- + 4 anti-neutrinos + 46.4 MeV 40K (0.012% of natural K) à 40Ca + e- + 1 anti-neutrino + 1.32 MeV (BR=89.3 %) 40K + e- à 40Ar + 1 neutrino + 1.505 MeV (BR=10.7 %) q the only direct probe of the deep Earth q released heat and geoneutrino flux in a well fixed ratio q to measure geoneutrino flux = (in principle) = to get radiogenic heat q in practice (as always) more complicated….. Earth shines in geoneutrinos: flux ~106 cm-2 s-1 leaving freely and instantaneously the Earth interior (to
    [Show full text]
  • Review Article Geoneutrinos
    Hindawi Publishing Corporation Advances in High Energy Physics Volume 2012, Article ID 235686, 34 pages doi:10.1155/2012/235686 Review Article Geoneutrinos Ondrejˇ Srˇ amek,´ 1 William F. McDonough,1 and John G. Learned2 1 Department of Geology, University of Maryland, College Park, MD 20742, USA 2 Department of Physics and Astronomy, University of Hawaii, Honolulu, HI 96822, USA Correspondence should be addressed to Ondrejˇ Srˇ amek,´ [email protected] Received 9 July 2012; Accepted 20 October 2012 Academic Editor: Arthur B. McDonald Copyright q 2012 Ondrejˇ Srˇ amek´ et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Neutrino geophysics is an emerging interdisciplinary field with the potential to map the abundances and distribution of radiogenic heat sources in the continental crust and deep Earth. To date, data from two different experiments quantify the amount of Th and U in the Earth and begin to put constraints on radiogenic power in the Earth available for driving mantle convection and plate tectonics. New improved detectors are under construction or in planning stages. Critical testing of compositional models of the Earth requires integrating geoneutrino and geological observations. Such tests will lead to significant constraints on the absolute and relative abundances of U and Th in the continents. High radioactivity in continental crust puts limits on land-based observatories’ capacity to resolve mantle models with current detection methods. Multiple-site measurement in oceanic areas away from continental crust and nuclear reactors offers the best potential to extract mantle information.
    [Show full text]
  • Experimental Aspects of Geoneutrino Detection: Status and Perspectives
    Experimental Aspects of Geoneutrino Detection: Status and Perspectives O. Smirnov,1 1JINR, Joint Institute for Nuclear Research, Dubna, Russian Federation October 22, 2019 Abstract Neutrino geophysics, the study of the Earth's interior by measuring the fluxes of geologically produced neutrino at its surface, is a new interdisciplinary field of science, rapidly developing as a synergy between geology, geophysics and particle physics. Geoneutrinos, antineutrinos from long- lived natural isotopes responsible for the radiogenic heat flux, provide valuable information for the chemical composition models of the Earth. The calculations of the expected geoneutrino signal are discussed, together with experimental aspects of geoneutrino detection, including the description of possible backgrounds and methods for their suppression. At present, only two detectors, Borexino and KamLAND, have reached sensitivity to the geoneutrino. The experiments accumulated a set of ∼190 geoneutrino events and continue the data acquisition. The detailed description of the experiments, their results on geoneutrino detection, and impact on geophysics are presented. The start of operation of other detectors sensitive to geoneutrinos is planned for the near future: the SNO+ detector is being filled with liquid scintillator, and the biggest ever 20 kt JUNO detector is under construction. A review of the physics potential of these experiments with respect to the geoneutrino studies, along with other proposals, is presented. New ideas and methods for geoneutrino detection are reviewed. Contents 1 Introduction 2 2 Geoneutrinos and the Earth's heat 4 2.1 Long-lived radiogenic elements . 4 2.2 Radiogenic heat and geoneutrino luminosity of the Earth . 9 arXiv:1910.09321v1 [physics.geo-ph] 21 Oct 2019 3 Geoneutrino flux calculation 11 3.1 Neutrino oscillations .
    [Show full text]
  • Neutrino Oscillations: the Rise of the PMNS Paradigm Arxiv:1710.00715
    Neutrino oscillations: the rise of the PMNS paradigm C. Giganti1, S. Lavignac2, M. Zito3 1 LPNHE, CNRS/IN2P3, UPMC, Universit´eParis Diderot, Paris 75252, France 2Institut de Physique Th´eorique,Universit´eParis Saclay, CNRS, CEA, Gif-sur-Yvette, France∗ 3IRFU/SPP, CEA, Universit´eParis-Saclay, F-91191 Gif-sur-Yvette, France November 17, 2017 Abstract Since the discovery of neutrino oscillations, the experimental progress in the last two decades has been very fast, with the precision measurements of the neutrino squared-mass differences and of the mixing angles, including the last unknown mixing angle θ13. Today a very large set of oscillation results obtained with a variety of experimental config- urations and techniques can be interpreted in the framework of three active massive neutrinos, whose mass and flavour eigenstates are related by a 3 3 unitary mixing matrix, the Pontecorvo- × Maki-Nakagawa-Sakata (PMNS) matrix, parameterized by three mixing angles θ12, θ23, θ13 and a CP-violating phase δCP. The additional parameters governing neutrino oscillations are the squared- mass differences ∆m2 = m2 m2, where m is the mass of the ith neutrino mass eigenstate. This ji j − i i review covers the rise of the PMNS three-neutrino mixing paradigm and the current status of the experimental determination of its parameters. The next years will continue to see a rich program of experimental endeavour coming to fruition and addressing the three missing pieces of the puzzle, namely the determination of the octant and precise value of the mixing angle θ23, the unveiling of the neutrino mass ordering (whether m1 < m2 < m3 or m3 < m1 < m2) and the measurement of the CP-violating phase δCP.
    [Show full text]
  • Exploring the Earth's Mantle with Geoneutrinos
    IL NUOVO CIMENTO Vol. 36 C, N. 1 Gennaio-Febbraio 2013 DOI 10.1393/ncc/i2013-11446-1 Colloquia: IFAE 2012 Exploring the Earth’s mantle with geoneutrinos ∗ G. Fiorentini(1)(2)(3),G.L.Fogli(4)(5),E.Lisi(5), F. Mantovani(1)(3)( ), A. M. Rotunno(4)andG. Xhixha(2) (1) Dipartimento di Fisica, Universit`a di Ferrara - Via Saragat 1, 44100 Ferrara, Italy (2) INFN, Laboratori Nazionali di Legnaro - Via dell’Universit`a 2 - 35020 Legnaro (PD), Italy (3) INFN, Sezione di Ferrara - Via Saragat 1, 44100 Ferrara, Italy (4) Dipartimento Interateneo di Fisica “Michelangelo Merlin” Via Amendola 173, 70126 Bari, Italy (5) INFN, Sezione di Bari - Via Orabona 4, 70126, Bari, Italy ricevuto il 31 Agosto 2012 Summary. — The KamLAND and Borexino experiments have observed, each at ∼ 4σ level, signals of electron antineutrinos produced in the decay chains of thorium and uranium in the Earth’s crust and mantle (Th and U geoneutrinos). Various pieces of geochemical and geophysical information allow an estimation of the crustal geoneutrino flux components with relatively small uncertainties. The mantle component may then be inferred by subtracting the estimated crustal flux from the measured total flux. On the base of this approach we find that crust- subtracted signals show hints of a residual mantle component, emerging at ∼ 2.4σ level by combining the KamLAND and Borexino data. The inferred mantle flux slightly favors scenarios with relatively high Th and U abundances, within ±1σ uncertainties comparable to the spread of predictions from recent mantle models. PACS 95.55.Vj – Neutrino, muon, pion, and other elementary particle detectors; cosmic ray detectors.
    [Show full text]
  • 100208 Mcdonough Ext
    PERSPECTIVES GEOPHYSICS Neutrinos created by nuclear decay may allow geoscientists to measure the distribution of Mapping the Earth’s Engine radioactive elements in the Earth. William F. McDonough article physicists and geophysicists optimal location for measuring the rarely meet to compare notes, but ear- Continental crust (>50%) distribution of heat-producing ele- lier this year researchers from these two Proposed Mantle (<50%) ments in the ancient core of a P geoneutrino disciplines gathered to discuss antineutrinos continent. Here, the antineutrino detectors (the antiparticle of the neutrino) (1). These signal will be dominated by the fundamental particles are a by-product of crustal component at about the reactions occurring in nuclear reactors and 80% level. This experiment will pass easily through Earth, but they are also SNO+ provide data on the bulk composi- generated deep inside Earth by the natural tion of the continents and place radioactive decay of uranium, thorium, and Core (~0%) limits on competing models of the potassium (in which case they are called continental crust’s composition. geoneutrinos). Particle physicists have re- The Boron Solar Neutrino experi- cently shown that it is possible to detect Hanohano ment (Borexino) detector, situated geoneutrinos and thus establish limits on the in central Italy (and hence some- amount of radioactive energy produced in the what removed from the regions of interior of our planet (2). This year’s joint France with many reactors), has meeting was aimed at enhancing communica- begun counting (5). This detector tion between the two disciplines in order to will accumulate a geoneutrino sig- on August 31, 2007 better constrain the distribution of Earth’s nal from a younger continental radioactive elements.
    [Show full text]
  • 40K Geoneutrino Detection
    40K Geoneutrino Detection Mark Chen Queen’s University and the Canadian Institute for Advanced Research Neutrino Geoscience 2015, Paris, France June 15, 2015 Why Potassium Geoneutrinos? n ~16% of Earth’s radiogenic heat is from 40K q would be good to quantify after 238U and 232Th n K/U ratio in chondrites > in the crust q would measurement help pin down abundances of other moderate volatiles in the Earth? n K may reside in the Earth’s core?? q e.g. Murthy, Lee and Jeanloz, Ohtani q does this help solve some core energetics issues (e.g. geodynamo, heat flow at CMB)? Th & U Volatility trend @ 1AU from Sun slide from Bill McDonough 40K Decay 40K→40Ca + e− +ν n 89.28% Qβ=1.311 MeV e 40 − 40 n 10.72% QEC=1.505 MeV K + e → Ar +ν e q 10.67% to 1.461 MeV state (Eν = 44 keV) q 0.05% to g.s. (Eν = 1.5 MeV) 0.0117% isotopic abundance 40K Spectrum + threshold for ν e + p → e + n [figure from KamLAND Nature paper] Potassium Geoneutrino Fluxes n (5-15) × 106 cm−2 s−1 for the antineutrinos 5 −2 −1 n (5-15) × 10 cm s for the 44 keV νe 3 −2 −1 n (2-6) × 10 cm s for the 1.5 MeV νe n compare to 1.44 MeV pep solar νe 8 −2 −1 1.42 × 10 cm s (and also CNO solar neutrinos at 1.5 MeV) You can probably forget about detecting the –5 1.5 MeV νe … only 63 keV away and 10 less intense! 40 K ν e Detection n ν e -e scattering q requires electron recoil directionality due to large flux of solar neutrinos (could imagine giant TPC) n 1/3 event per ton per year n NC nuclear excitation q not distinctive from νe or γ nuclear excitation n NC coherent neutrino-nucleus scattering
    [Show full text]
  • Expected Geoneutrino Signal at JUNO
    Expected geoneutrino signal at JUNO Virginia STRATI1,2,*, Marica BALDONCINI1,3, Ivan CALLEGARI2, Fabio MANTOVANI1,3, William F. McDONOUGH4, Barbara RICCI1,3, Gerti XHIXHA2 1 Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, 44121 - Ferrara, Italy 2 INFN, Legnaro National Laboratories, Viale dell’Università, 2 - 35020 Legnaro (Padua) Italy 3 INFN, Ferrara Section, Via Saragat 1, 44121 - Ferrara, Italy 4 Department of Geology, University of Maryland, 237 Regents Drive, College Park, MD 20742, USA. *Corresponding author Email: [email protected] Abstract 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 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, each one having a planned thermal power of approximately 18 GW. 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. 6.5 The predicted geoneutrino signal at JUNO is 39.75.2 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 ~500 km) the detector. A special focus is dedicated to the 6° × 4° Local Crust surrounding the detector which is estimated to contribute for the 44% of the signal.
    [Show full text]
  • Updated Geoneutrino Measurement with the Borexino Detector
    Updated Geoneutrino Measurement with the Borexino Detector Aktualisierte Geoneutrino-Messung mit dem Borexino-Detektor von Sindhujha Kumaran Master arbeit in Physik vorgelegt der Fakultat¨ fur¨ Mathematik, Informatik und Naturwissenschaften der RWTH AACHEN September 2018 angefertigt im Physikalischen Institut III. B Erstgutachter und Betreuer Zweitgutachter Prof. Dr. Livia Ludhova Prof. Dr. Achim Stahl Physikalischen Institut III. B Physikalischen Institut III. B RWTH Aachen RWTH Aachen Ich versichere, dass ich die Arbeit selbstst¨andigverfasst und keine anderen als die angegebenen Quellen und Hilfsmittel benutzt sowie Zitate kenntlich gemacht habe. Aachen, den To my dearest brother, Aswin. \That you are here|that life exists and identity, That the powerful play goes on, and you may contribute a verse." -O Me! O Life!, Walt Whitman Abstract Geoneutrinos are electron antineutrinos and neutrinos emitted in the radioactive decays from the Earth's interior. Due to the intrinsic dependence of the geoneutrino flux and the heat produced in 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 the abundance 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 flux and the nature of the mantle still remain as open questions. The combination of the total geoneu- trino flux (≈106 cm−2s−1) and the weak interaction cross section (≈10−42 cm−2s−1) lead to huge statistical uncertainties in the current measurements. This has made the study of geoneutrinos quite challenging and so far, only two detectors, namely KamLAND and Borexino, have measured geoneutrinos.
    [Show full text]
  • Geoneutrinos and the Heat Budget of the Earth
    Geoneutrinos and the heat budget of the Earth Ondřej Šrámek University of Maryland presented at Department of Geophysics, Charles University in Prague on 14 November 2012 Collaboration with Bill McDonough (UMD), Steve Dye (HPU), Shijie Zhong (UCB), Edwin Kite (Caltech), Vedran Lekić (UMD) Seismology Geodynamics Mineral physics Experimental Geochemistry particle physics ......... Geoneutrinos “Geoneutrinos” = electron anti-neutrinos emitted in β− decays of naturally occurring radionuclides geo-ν’s now detectable ... and have been detected Measuring radioactivity of the Earth! How much radiogenic heating in the mantle?? What is the Earth made of?? Chemical reservoirs in the mantle?? 1. geophysical motivation 2. neutrino history 3. antineutrino production, propagation, detection 4. observations of geoneutrinos 5. predictions of geoneutrinos flux 6. perspectives Radiogenic heating rate in the mantle...? How do we know it...? heat output (surface heat flux) 238U primordial heat + 232 radiogenic heating Th 40K ? How much radiogenic heating in the Earth? How is it spatially distributed? ... implications for geodynamics U Th K Composition of Silicate Earth • U, Th, K are lithophile elements, strong arguments against presence in the core • Composition of “Silicate Earth” (BSE) of interest, Silicate Earth = whole Earth minus the core • [But: some unorthodox models even predicting natural nuclear reactor in Earth’s deep interior] • Cosmochemistry and geochemistry: BSE compositional estimates • Difficult. Usual problem in geophysics: rock samples only
    [Show full text]
  • Editorial Neutrino Masses and Oscillations
    Hindawi Publishing Corporation Advances in High Energy Physics Volume 2014, Article ID 823127, 4 pages http://dx.doi.org/10.1155/2014/823127 Editorial Neutrino Masses and Oscillations Elisa Bernardini,1 Leslie Camilleri,2 Vincenzo Flaminio,3 Srubabati Goswami,4 and Seon-Hee Seo5 1 DESY, Platanen Allee 6, 15738 Zeuthen, Germany 2 Columbia University 435 W. 116th Street, New York, NY 10027-7201, USA 3 Physics Department and INFN, Largo Bruno Pontecorvo, 56127 Pisa, Italy 4 Physical Research Laboratory, Navrangpura, Ahmedabad 380009, India 5 Department of Physics and Astronomy, Seoul National University, Republic of Korea Correspondence should be addressed to Vincenzo Flaminio; [email protected] Received 17 December 2013; Accepted 17 December 2013; Published 30 March 2014 Copyright © 2014 Elisa Bernardini et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The publication of this article was funded by SCOAP3. The year 2013 marks the 100th anniversary of the birth of originated a vast number of both experimental and theoreti- Bruno Pontecorvo, who first suggested the possibility that cal developments. neutrinos might have a nonzero mass such that oscillations The original ideas (1957-58) are first considered in this among different neutrino states might occur. Pontecorvo paper. This is followed by the consideration of a later paper constantly pursued this idea, after the discovery of other by Pontecorvo on neutrino oscillations (1967) and by the neutrino flavours, until his death. anticipation of the solar neutrino problem.
    [Show full text]
  • GEONEUTRINO RADIOMETRIC ANALYSIS for GEOSCIENCES (GRAFG) at DUSEL HOMESTAKE, SOUTH DAKOTA White Paper Update to DEDC, June 30, 2008
    GEONEUTRINO RADIOMETRIC ANALYSIS FOR GEOSCIENCES (GRAFG) AT DUSEL HOMESTAKE, SOUTH DAKOTA White Paper Update To DEDC, June 30, 2008 by P. ILA, W. GOSNOLD, G. I. LYKKEN, P. JAGAM Abstract Neutrino detection is a mature area of research, which is rapidly developing in the area of particle physics to improve detection sensitivities and optimization for specific applications. Large-scale detectors (meaning kilo-ton or more in size) were designed and built to study particle physics properties and solar neutrinos. Recently a 1-ton detector was optimized for detecting the antineutrinos from a power reactor. Directionality in the detection of the neutrinos was exploited in Cerenkov detectors. In this context it was realized the 1-ton detector is competitive and mobile for certain applications in geosciences. The cost of building large detectors is in the range of few hundred millions dollars. The 1-ton detector can be built for under10 million dollars. A fully tested and used detector may be available for immediate research and development purposes in geosciences. Our goal is to develop a radiometric method using antineutrinos from the Earth for in-situ determination of the heat producing elements (HPE) in regions inaccessible to conventional sampling techniques. We also want to investigate correlations with HPE in different geothermal regions. Page 1 of 21 INTERESTED PRINCIPALS, COLLABORATORS AND OTHERS Working Group Members: • Group Leader and Low Radioactivity Measurement of HPE: Dr. P. Ila, Earth, Atmospheric and Planetary Sciences Dept., Massachusetts Institute of Technology, Cambridge, MA • Heat Flow/Geophysics: Prof. W. Gosnold, Geology and Geological Engineering Dept., Grand Forks, University of North Dakota, ND • Cosmic-ray Physics: Prof.
    [Show full text]