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XXXIXth RENCONTRES DE MORIOND 2004 – ELECTROWEAK INTERACTIONS AND UNIFIED THEORIES La Thuile, Aosta Valley, Italy (March 21-28, 2004) GeoNeutrino Analysis in KamLAND: Input and Desiderata Anna Maria Rotunno Dip.to di Fisica & Sez. INFN, Bari, ITALY [email protected] 1 Outline: GeoNeutrinos GeoNeutrinos Geochemical GeochemicalInput Input Desiderata Desideratafor forKamLAND KamLANDData DataAnalysis Analysis Conclusions Conclusions Report on WORK IN PROGRESS with: G.L. Fogli, E. Lisi, A. Palazzo 2 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) Geoneutrinos 3 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) Earth is an Anti-Neutrino Star νe Radioactive Decays in U,Th,K … CRUST and MANTLE νe - Radiogenic Heat (40-60 % of 40 TW) - Geo – Antineutrinos observable by terrestrial detectors (liquid scintillators) Geo – νe detection Important Constraints for Earth’s energetics 4 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) Geochemical Input 5 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) Radioactive decay of U, Th, and K in the Earth is thought to be the main source of the Earth heat flux (*) νe events from Th and U decay are accessible for the first time in KamLAND (νe from K decay are below threshold for detection). ΦTh(νe) and ΦU(νe) in KamLAND are weighted by 1/L2 & (Th, U, K) are more abundant in the CRUST than in the MANTLE some INPUT on the relative Th, U (and K) abundances in different Earth reservoirs is needed to make sense of (*) For a recent review See FUTURE GEONEUTRINO DATA G. Fiorentini et al., hep-ph/0309013 6 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) QUESTIONS: What do we really know about such aboundances? What do we expect to know from Th,U Geo-νe data ? Usually advertised goal: “ measure the Earth Radiogenic Heat” 7 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) HOWEVER, even if the Th and U components were known with no error, there would be INTRINSIC LIMITATIONS to this goal: 1) K component unmeasurable (in KamLAND); must be inferred from K/U or K/Th estimates 2) K/U, K/Th bulk ratios not constrained by meteoritic data, since K is geochemically “volatile” (= lower condensation temperature than Th, U) 3) Crust+Mantle sampling data + geochemical arguments unlikely to reduce the K/U, K/Th uncertainty below, say, 10÷15% (*) 4) Possible significant amount of Potassium (but not of Th, U) in Earth’s core (**) 5) Possible severe overestimation of the usually quoted Earth’s heat flux, 44±1 TW (***) , by oceanic component systematics. Possible revisited value of Earth’s heat flux : 31±1 TW (****) (*) K.P. Jochum et al., Nature 306, 431 (1983) (**) V. Rama Murthy et al., Nature 423, 163 (2003); Lee & Jeanloz, Geophys. Rev. Lett. 30, 2212 (2003) (***) H.N. Pollack et al., Rev. Geophys. 31, 267 (1993) (****) Hofmeister & Criss, preprint, submitted to Tectonophysics 8 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) QUESTION: Can one say something useful to GEOPHYSICS by JUST MEASURING Th and U νe fluxes ? YES. ONE EXAMPLE . . . 9 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) • Bulk Th/U ratio in the Earth should be close to meteoritic value: (Th/U)Earth = (Th/U)chondritic ~ 3.8 • No geochemical or cosmochemical arguments to think otherwise Th more easily partitioned than U in melt (= Crust) than in solid (= Mantle) (Th/U)Crust > 3.8 (Th/U)Mantle < 3.8 (probably 4.5÷5.5) (probably 2 ÷ 3) observations match expectations • Geo-ν experiments dominated by Crust contribution (including KamLAND) should then observe (Th/U)Crust-dominated > 3.8 (up to local crust fluctuations) • This datum + Crust and Upper Mantle sampling might provide an estimate of: (Th/U)Lower-Mantle by mass balance arguments (*) Can infer MANTLE LAYERING if (Th/U)Lower-Mantle (Th/U)Upper-Mantle (*) D.L. Turcotte et al., J. Of Geophys. Res. 106, 4265 (2001) 10 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) PROBLEM: How do we ATTACH ERRORS to (Th,U) estimates? 1st ORDER SOLUTION (Fiorentini et al.): evaluate central values and errors from spread of published (Th,U) estimates; e.g., attach ±3 σ significance to extremal values. A good starting approach but . . . . . . LIMITATIONS: 1) published estimates are often “duplicates” (≡ may agree too well ) 2) without a criterion to discard obsolete estimates or unreliable outliers, NO PROGRESS POSSIBLE with this approach No other way out than carefully sifting the available geo-literature, identifying virtues and problems of each estimate, selecting the more reliable and complete ones, WORK IN PROGRESS and evaluating from scratch the uncertainties UNFORTUNATELY: error evaluation not common practice in geo-sciences ! 11 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) E.G. only recently (2003) a geochemical Earth model has appeared, where input uncertainties are at least well-defined (although questionable in size) and correctly propagated to output element abundances (*) Palme 2003 estimates for the bulk silicate Earth (= Mantle + Crust) at 1σ: [Th] = 83.5 (1±0.12) ppb (part per billion in weight) [ U ] = 21.9 (1±0.12) ppb (part per billion in weight) with correlation ρ = 0.38 (our provisional estimate) Th/U 3.8 (1±0.14) (bulk Earth) This estimate can actually be refined through a more careful use of meteoritic (chondritic) data IMPORTANT TASK since (Th/U)Earth plays a pivotal role in Mantle-Crust balances: (Th/U)Crust > (Th/U)Earth (testable by KamLAND) (*) WORK IN PROGRESS (Th/U)Mantle < (Th/U)Earth (useful to test Lower/Upper Mantle differences) H. Palme & H. O’Neill, in “Treatise on Geochemistry”, Elsevier, 2003 12 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) This global information must be folded with careful estimates of “geometrical” (Th/U) variations, both VERTICAL (Crust layers + Mantle layers) and HORIZONTAL (Crust types) In principle, large amount of data and constraints are available, but dedicated global studies are still lacking. Interaction with geo-science community would be beneficial. 13 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) Desiderata for KamLAND Data Analysis 14 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) What can we know from KamLAND? A model-independent check that, e.g., (Th/U)Crust > 3.8, requires Th, U Current (binned) data FREE constraints, of course, very weak BINNED ANALYSIS Since the statistics will be very low for quite some time, it is necessary to use Th/U = 3.8 as much information as possible. 15 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) FIRST STEP: avoid binning and tag each event in energy (recoverable from KamLAND plots) Unbinned analysis of KamLAND data (through maximum likelihood) yields slightly TIGHTER CONSTRAINTS on Th, U contributions. It should be used as a default. UNBINNED ANALYSIS Th/U = 3.8 DESIDERATUM 1: the KamLAND Collaboration should provide energy of each event 16 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) NOTICE THAT unbinned analysis provides BETTER CONSTRAINTS either on Th, U contribution or on oscillation parameters See also: T. Schwetz, hep-ph/0306226 17 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) SECOND STEP: use also TIME INFORMATION. Geo-ν flux is constant BUT total reactor flux follows ~ seasonal variations + possible shut-downs (info completely known to KamLAND Collaboration) additional handle TO SEPARATE constant Geo-ν from variable reactor signal (*) IF AN UNBINNED ENERGY-TIME MAXIMUM LIKELIHOOD IS USED (*) See comments in Ethreshold= 2.6 MeV E. Lisi, A.M. R. and A. Palazzo et al., hep-ph/0403036 18 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) DESIDERATUM 2: for each KamLAND event, ENERGY + TIME INFORMATION should be released & REACTOR FLUX HISTORY should also be provided Concerning the future, the list of desiderata must certainly include NEW EXPERIMENTS in sites with both LOWER & HIGHER FLUX - BOREXINO ? - LENA ? - Sudbury ? - Hawaii ? - Backsan ? . . . . . More experiments also needed to average out local uncertainties in (Th,U) distributions 19 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) Conclusions 20 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004) • KamLAND will start the NEW FIELD of geo-ν observations, and might be followed by other similar experiments • LARGE UNCERTAINTIES might hide the underlying (geo)physics for quite some time, but steady progress can be envisaged, if the particle physics and geo-physics communities identify COMMON GOALS. In particular: An effort can and should be made to characterize the GEOPHYSICAL and GEOCHEMICAL input in “particle physics language”: central values, errors and correlations, e.g. on Th/U ratio. Missing input should be identified and worked out by the two communities. The FEW GEO-ν EVENTS which will be COLLECTED BY KamLAND (and possibly other experiments) in the future deserve our best analysis tools, so as to squeeze the maximum amount of information. TIME & ENERGY TAGGING of each individual event can help the geo-ν/reactor discrimination. Full publicity and full information for each event and each reactor history is essential to achieve this goal. 21 Anna Maria Rotunno XXXIXth RENCONTRES DE MORIOND 2004 – La Thuile, Aosta Valley, Italy (March 21-28, 2004)