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Geo Neutrino Detection at KamLAND

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. Story of this talk. * KamLAND experiment * Geo neutrino * Observation of geo neutrino * Summary. n e world.

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Geo Neutrino Detection at KamLAND

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  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

  3. ne world

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

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

  6. Monitor Displays Water Purification system Rn free N2 Gas Generator Corridor to detector 8 Oil Purification system

  7. Key Detector Elements * Liquid Scintillator: Dodencane(80%)+PC(20%)+PPO(1.5g/L) (1150m3) Light output >8,000photons/MeV latt.>10m * Balloon: 13m diam. 135mm 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 + N2 bubbling U =>3.5x10-18g/g

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

  9. shimizu

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

  11. A brief history of KamLAND Detector Construction 1997~ Start Data Taking 01/2002 1st reactor paper (deficit) 12/2002 (PRL 90:021802,2003) Solar ne 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 n 2007~ 3rd reactor paper(precision) 2008(PRL 100, 221803 (2008)

  12. Geo Neutrinos Nature 436, 28 July 2005

  13. The 1st geo neutrino paper for KamLAND

  14. shimizu

  15. ne fromU/Th/K decay U series: Qheat=49.7MeV Th series: Qheat=40.4MeV nep threshold suekane 05 Erice School

  16. 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?

  17. shimizu KamLAND data

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

  19. shimizu

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

  21. 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 13C (a,n)16O background will be removed.

  22. Back up slides

  23. Shimizu

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