Perspectives for geoneutrinos after KamLAND results based on work with L. Carmignani, G. Fiorentini, T. Lasserre, M. Lissia, B. Ricci, S. Schoenert, R. Vannucci Neutrino Geophysics Honolulu – December 14-16, 2005 Neutrino Geophysics Honolulu – December 14-16, 2005 Fabio Mantovani Sienna University - Italy Fabio Mantovani Sienna University - Italy Predictions of the Reference Model and its uncertainties KamLAND results and improvements The goals of future experiments Beyond the Reference Model How much Uranium is in the Earth? Who is the enemy of geoneutrinos?

The Reference Model Event yields from U and Th over the globe have been calculated by using:  Observational data for Crust and Upper Mantle  The BSE (Bulk Silicate Earth) Model constraint for Lower Mantle  Best fit -oscillation parameters  Th/U consistent with with chondritic prediction Predicted events are: about 30 per kiloton.yr, depending on location ¾ originate from U, ¼ from Th decay chains

The Reference Model for KamLAND We predict * the produced antineutrino flux… For Uranium: For Uranium: For Thorium: For Thorium: * F. Mantovani et al. – Phys. Rev. D 69 – hep-ph/ From the fluxes to the signals… 1 TNU = Terrestrial Neutrino Units: one event per protons per year Average survival probability = 0.59 Average survival probability = 0.59 Detector efficiency 100% Detector efficiency 100%

The origin of the flux at KamLAND… 3.2 %3.3 % 41.6 %40.4 % 28.8 %32.4 % 5.2 %3.4 % 20.8%20.3% 0.4 %0.2 % Oceanic Crust Contribute to the  [U] in percentage Contribute to the  [Th] in percentage

We use a 2° x 2° degrees crust map, which distinguishes several components (OC and CC, sediments, upper, middle, lower) 45 % of S(U) is produced by 6 tiles* The better you know the geochemical and geophysics properties of the region around the detector… …the better you will be able to understand the interior of the Earth! * G. Fiorentini et al. - Phys.Rev. D72 – hep-ph/ / S. Enomoto PhD Thesis The region near KamLAND

KamLAND Refining the Reference Model…  A geochemical study of the Japan upper crust  Detailed measurements of crust depth We use…  Selected values for Lower Crust  (3  ) errors on sample activity measurements Taking into account…  Finite resolution of geochemical study  Uncertainty from the Japan sea crust characterization  Uncertainty from subducting plates below Japan  Uncertainty of seismic measurements

KamLAND Refining the Reference Model…  S [TNU] Composition of the upper-crust sample 1.0 Upper-crust discretization 1.7 Lower-crust composition 0.8 Crustal depths 0.7 Subducting slab 2.1 Japan Sea 0.3 Regional uncertainties* * G. Fiorentini et al. - Phys.Rev. D72 – hep-ph/ / S. Enomoto PhD Thesis What about the contribution from the rest of the world S RW ? It depends…

How much Uranium is in the Earth? And where is it? The contribution from the rest of the world depends on the total mass of Uranium m as well as on its distribution inside the Earth Crust :  Crust : [Based on geochemical data] Note: Uranium mass in unit of kg ; signal in unit of TNU Mantle:  Mantle: Uniform abundance Thin layer at the bottom The proximity argument Poor Rich m crust (U) LowRetreated Signalm man (U) HighHomogeneous

The uncertainties* of the Reference Model at KamLAND  uncertainty of the regional contribution uncertainty from the global Earth's structure and composition  uncertainty from the global Earth's structure and composition For the central value of the BSE model we predict at KamLAND:  uncertainty from oscillation parameters * G. Fiorentini et al. - Phys.Rev. D72 – hep-ph/

Beyond the Reference Model*: Signal and Heat at KamLAND U and Th measured in the crust implies a signal at least of 24 TNU Earth energetics implies the signal does not exceed 62 TNU BSE prediction is a signal between 31 and 43 TNU BSE prediction is a signal between 31 and 43 TNU * G. Fiorentini et al. - Phys.Rev. D72 – hep-ph/

In this scenario… where are KamLAND results? The KamLAND signal is: From the geoneutrino signal to power relationship we get: Consistent within 1  with: BSE model BSE model Fully radiogenic model Fully radiogenic model BSE model BSE model Fully radiogenic model Fully radiogenic model The 99% CL upper bound on geo-signal translates into*: * G. Fiorentini et al. - Phys.Lett. B 629 – hep-ph/

How to make the most of KamLAND signal* Evidence for geoneutrinos: near to 2.5  Minor background Geoneutrino* Fake geo-neutrinos from 13 C( ,n) Reactor events N event In 749 days 152 counts in the geoneutrino energy range * With anti-ν spectrum analysis * G. Fiorentini et al. - Phys.Lett. B629 – hep-ph/ / **S. Harissopulos et al The 13 C( ,n) cross section is based on relatively old data [JENDL]: 20% overall uncertainty Recent** high precision measurments confirm JENDL data with 4% accuracy:

Who is the enemy of geoneutrinos? 0.5LENA 0.2Baksan 0.2Homestake 0.1Hawaii 0.9Borexino 0.1Curacao 1.1Sudbury 6.7KamLAND r All reactors at full power All reactors at full power Based on International Atomic Energy Agency Database (2000) Based on International Atomic Energy Agency Database (2000) All reactors at full power All reactors at full power Based on International Atomic Energy Agency Database (2000) Based on International Atomic Energy Agency Database (2000) In the geo-neutrino energy window The nuclear reactors!

The goals of future experiments Definite evidence of geoneutrinos (3  at least) How much Uranium and Thorium in the crust? …..….. How much Uranium and Thorium in the mantle?

The relation between signal [TNU] and heat [TW] S (U+Th) [TNU] H (U+Th) [TW] Sudbury BaksanLENA Homestake Borexino KamLAND Curacao (EARTH) Hawaii Fully Radiogenic BSE a is the universal slope: b depends on: U and Th mass in the crust location of the detector

Measuring radioactivity from the crust… Signal (U+Th) expected from the crust* [TNU] Signal (U+Th) expected from the mantle* [TNU] Signal (U+Th) total [TNU] LENA Homestake Sudbury Baksan * Based on the Reference Model constraints for each detector, almost 80% of the signal is expected from the crust the uncertainties can be minimized studying the geochemical and geophysics properties of the region around the detector these detectors will have excellent opportunities to determine the Uranium and Thorium abundance in the crust Homestake and Baksan have a better r factor (E reactor /E geo )

Signal (U+Th) expected from the crust* [TNU] Signal (U+Th) expected from the mantle* [TNU] Signal (U+Th) total [TNU] Borexino KamLAND Curacao Hawaii * Based on the Reference Model constraints Borexino: good for U and Th signal from the crust. It has a low r factor, but it has a small mass Curacao: almost 25% of the signal is expected from the mantle and it has a low r factor (E reactor /E geo ) KamLAND: it has a high r factor (E reactor /E geo ). It will be the first experiment which provide a definite evidence of geoneutrinos (3  ) Hawaii: almost 70% of the signal is expected from the mantle and it has a low r factor (E reactor /E geo ) Measuring radioactivity from the mantle…

Can geoneutrinos measure the plume’s depth? A mantle plume is an upwelling of anomalously hot rock in the Earth's mantle. Mantle plumes are thought to be the cause of volcanic centers known as hotspots: Hawaii island is the most famous hotspot With h p >>r p the geoneutrinos flux depends on the asymptotic value  as proportional to a p and r p Detector hphp rprp We assumed* cylindrical plume with uniform density and Uranium abundance a p (U) The U-neutrino flux from a plume with r p = 350 km, h p = 2800 km and a p (U) = 40 ppb is about 20% of that from the whole mantle. * Fiorentini et all. - Earth and Planetary Science Letters, Volume 238, physics/ Computer simulation of a mantle plume by Hawaii Scientific Drilling Project web site

The lesson of solar neutrinos The study of solar neutrinos started as an investigation of the solar interior. Homestake experiment (Raymond Davis and colleagues) see the first solar neutrinos… A long and fruitful detour lead to the discovery of oscillations. Through several steps, we have now a direct proof of the solar energy source, we are making solar neutrino spectroscopy, we have neutrino telescopes.

Follow this lesson! The study of geoneutrinos started as an investigation of the interior of the Earth [Eder 1966 – Marks 1969] What’s the next?… KamLAND experiment found the first evidence of geoneutrinos. The technique for identifying geo-neutrinos is now available.

…geoneutrinos is a ‘baby instrument’ that permit us to look the Earth with new eyes… Let it grow!

Extra slides…

Predictions of the Reference Model at KamLAND KamLAND: Ref. Model Phys. Rev. D – 2004 KamLAND: Araki et al. Nature

The Reference Model THE CRUST U [ppm]Th [ppm] Water 0,00320 Sediments 1,686,9 Upper crust * 2,59,8 Middle crust 1,66,1 Lower crust ** 0,623,7 Oceanic Crust 0,10,22 * Average of: ** Average of: A X depends on the life time, atom mass and number of antineutrinos per decay chains Th/U = 3,8 ; 3,8 ; 3,9 ; 4,1 U = 2,2 ; 2,4 ; 2,5; 2,8 Th/U = 3,8 ; 6,0 ; 7,0 ; 7,1 U = 0,2 ; 0,28 ; 0,93 ; 1,1

The Reference Model THE MANTLE Assumptions  Spherical symmetry  Two reservoirs (geochemistry’s model) : discontinuity line at ~ 600 km under the earth surface  Uranium abundance in the Upper Mantle 6,5 ppb (the average of 5 ; 8 ppb)  The amount of Uranium mass in the Lower Mantle is obtained by the equation: M LM (U) = M BSE (U) – [ M CC (U) + M OC (U) + M UM (U) ] UraniumMass [10 17 kg]Abundance [ppb] Upper Mantle0,0626,5 Lower Mantle0,38913,2

Predictions of the Reference Model at KamLAND U [ppm]Th [ppm]  [U]  [Th] Water 0, Sediments 1,686,90,1170,108 Upper crust * 2,59,81,5181,309 Middle crust 1,66,10,7730,684 Lower crust ** 0,623,70,2790,366 Oceanic Crust 0,10,220,0170,008 Upper Mantle0,00650,01730,1890,111 Lower Mantle0,01320,0520,7600,658 Tot3,6533,244

The uncertainties of the Reference Model at KamLAND The abundance ratios look relatively well determined: we concentrate on the uncertainties of the uranium abundances in the different layers and propagate them to the other elements. (1) S. R. Taylor and S.M. McLennan 1985 (2) D. M. Shaw et al The crust Using a 2° x 2° Crustal Model, for each of the six components we have fixed: Thickness [Km] Density [g/cm3] Abundance of Uranium [ppm] Using a 2° x 2° Crustal Model, for each of the six components we have fixed: Thickness [Km] Density [g/cm3] Abundance of Uranium [ppm] We obtained:

A few words on directionality… Bin cos max (  )

Directionality at KamLAND… Bin < Horizontal Vertical >

Directionality at Hawaii… Bin < Horizontal Vertical > Bin