1. Geo Neutrino Detection at KamLAND F.Suekane RC S Tohoku University 5th Workshop on Applied Antineutrino Physics (AAP2009) Angra dos Reis, Brazil 20/03/2009

2. Story of this talk * KamLAND experiment * Geo neutrino * Observation of geo neutrino * Summary

4. e world

5. Main purpose of KamLAND is to explore the e world with; world largest & low-background liquid-scintillator e detector.

7. 05.09.19suekane 05 Erice School7 KamLAND Detector Cosmicray veto Balloon S.S. tank PMT Liquid Scintillator buffer oil Electronics

8. 8 Oil Purification system Rn free N 2 Gas Generator Corridor to detector Water Purification system Monitor Displays

9. Key Detector Elements * Liquid Scintillator: Dodencane(80%)+PC(20%)+PPO(1.5g/L) (1150m 3 ) Light output >8,000photons/MeV att. >10m * Balloon: 13m diam. 135  m thick Nylon/EVOH multilayer film. Held by Kevlar mesh. * PMT: 1325 17" aperture fast PMT (Newly developed) + 554 20" aperture (Kamiokande PMT) 34% photo-coverage * Purification system: Water extraction + N 2 bubbling U =>3.5x10 -18 g/g

10. e detection ( e p -> e + n); an ideal reaction, because Only e contributes (no background from other neutrino species) Low threshold Energy (1.8MeV) Large cross section (~100  e ) p is abundant in LS Cross section precisely known (  =0.2%) e energy can be measured (E =E visible +0.8MeV) Delayed Coincidence -> powerful background rejection

11. shimizu

12. Event Display: Low Energy Event (Enomoto WIN05)

13. A brief history of KamLAND Detector Construction 1997~ Start Data Taking 01/2002 1st reactor paper (deficit) 12/2002 (PRL 90:021802,2003) Solar e search 2003 (PRL 92:071301,2004) 2nd reactor paper(spectrum) 2004 (PRL 94, 081801,2005) Geo neutrino paper 2005 (Nature 436:499-503,2005) n decay 2006 (PRL96:101802-101807,2006) LS purification for Solar  2007~ 3rd reactor paper(precision) 2008 (PRL 100, 221803 (2008)

14. Geo Neutrinos Nature 436, 28 July 2005

15. The 1 st geo neutrino paper for KamLAND

16. shimizu

17. suekane 05 Erice School e p threshold U series: Q heat =49.7MeV Th series: Q heat =40.4MeV e from U/Th/K decay

18. Why Geo-Neutrinos? Observation of Geo neutrino  Abundance and Localization of U and Th  Thermal Structure and History of the earth - Is the earth cooling or equilibrium state? - What is the future of the earth? - What is the residual heat of the earth formation? - What drives the geo magnetic field?

19. KamLAND data shimizu

20. => Consistent with the expectation shimizu (17±6.2TW)

21. shimizu

22. Purification of liquid scintillator This BKG will be gone. Clean LS shimizu

23. Summary * The geo neutrino flux is observed to be 38.9 +14.4 -14.2 TNU. This is consistent with the expectation of 36.9TNU (16TW) and there is no surprise. * KamLAND is purifying LS and the large 13 C (a,n) 16 O background will be removed.

24. Back up slides

25. Shimizu