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KamLAND Status for Solar Neutrino Phase

KamLAND Status for Solar Neutrino Phase. Yasuhiro Kishimoto for KamLAND collaboration RCNS, Tohoku Univ. September 12, 2007 TAUP 2007 in Sendai. KamLAND. 1.36g/l. Physics target of KamLAND. Next target.

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KamLAND Status for Solar Neutrino Phase

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  1. KamLAND Status for Solar Neutrino Phase Yasuhiro Kishimoto for KamLAND collaboration RCNS, Tohoku Univ. September 12, 2007 TAUP 2007 in Sendai

  2. KamLAND 1.36g/l

  3. Physics target of KamLAND Next target

  4. Prediction of solar n flux • Heavy elements abundance • Strong disagreement with helioseismological measurement • Nuclear reaction cross sections (LUNA) • 3He(a, g)7Be, 14N(p, g)15O

  5. Solar neutrino status • Borexino succeeded 7Be observation. • KamLAND plans to measure 7Be and CNO n to test the solar model (AGS05). arXiv:0708.225lv2 [astro-ph]

  6. KamLAND spectrum (Before purification) 7Ben Main BG: 85Kr 210Bi, 210Po, 40K CNOn Main BG: 40K, 11C Fiducial R<4m

  7. History of Purification studies • 2002~ 2006 • Small and middle size test bench • Summer in 2006 ~ • Construction • Autumn and winter in 2006 • Shake down

  8. Reduction efficiency (test bench results)

  9. Purification System • Distillation against metals and ions • N2 purge against Kr, Ar, and Rn.

  10. Status during 1st Purification • LS purification rate: F=0.9t/h • Parameters were well controlled .

  11. Status during 1st Purification • 222Rn measurement →OK(<10mBq/m3) • miniLAND • Electro static collection method • See posters. • Nat.Kr measurement • Cold trap + RGA • Light yield and attenuation length of LS • 222Rn and85Kr arecounted with KamLAND

  12. 1st Purification • Total 1699m3of LS was purified through Aug. 1st, 2007. • Purified Volume / KamLAND volume = 1.4 • Reactor and geo neutrino observation ware continuing .

  13. Status during the 1st purification Preliminary Vertex distribution (0.45 MeV <E<0.70 MeV)

  14. Status during the 1st purification • Lighter LS was installed. • Dr~0.03% • Last 173m3 • 14.4% of KamLAND (Z>3.4m) • Succeeded to keep LS boundary. Preliminary Vertex distribution (Aug. 1-17) (0.45 MeV <E<0.70 MeV)

  15. Status after purification Lower part z [m] x2+y2 [m2] Preliminary

  16. Status after purification Upper part z [m] x2+y2 [m2] Preliminary

  17. Status after the 1st purification (cont.) Red figure: Upper region (Z>4m) Blue figure: Lower region (Z<3m) The activity are still high for 7Be and CNO n, but 210Po reduction helps reactor and geo n measurement a lot because of lower (a, n) background.

  18. Toward 2nd purification • Prevent mixing • T, r, F, …

  19. Toward 2nd purification (cont.) PPO was extracted. • Much more careful distillation • SmallDT, DP, … • Real-time BG monitor for quick feedback • Energy estimation NP+PPO is installed. Pressure [kPa] Temperature [C] PPO is distilled. Time [h]

  20. 2nd purification campaign • We stopped our purification activities . • Blasting in Kamioka mine by next spring • We are going to upgrade our apparatus . • And we start 2nd purification campaign after blasting.

  21. For CNO neutrino measurement

  22. 11C rejection by neutron events Point like (NO track. → Smaller dead time) • Triple coincidence events • Cosmic m • Neutron (Capture time ~210msec) • 11C (Lifetime=29.4min.) • Neutron tagging is important. Requirement for dead time free electronics 12C + X → 11C + n + Y (Br~95%) X=g, n, p, p, e, m, …

  23. Energy spectra after 11C rejection • Expected CNO n+ pep n flux error ~ 6% (Stat. error) Prototype was tested. Go poster session to see results.

  24. Summary • 1st purification of KamLAND liquid scintillator has been accomplished. • Reduction in KamLAND activities are still being determined. • 2nd purification will start in Spring of next year. • New electronics is being developed for CNO n.

  25. Backup 40K

  26. Status during 1st Purification • Light yield measurement • Measure Compton edge of 60Co (1.1, 1.3keV) • No significant change was observed.

  27. Status during 1st Purification • Attenuation length measurement • L~4.9m

  28. LS density

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