Kam LAND Future Prospects Atsuto Suzuki Tohoku University

Kam. LAND Future Prospects Atsuto Suzuki Tohoku University Kam. LAND Collaboration III Int. Workshop on Neutrino Oscillations in Venice Feb. 7 -10, 2006

Outline 1. Kam. LAND-II 2. Prospects of Solar Neutrino Detection 3. 3. Toward Precise Measurement of 4. Reactor Neutrinos 5. 4. More and more Geoneutrinos 5. Conclusions

1. Kam. LAND-II (summer in 2006) ※ 7 Be solar neutrino detection: JSPS 5 -year project from 2004 ※ Precise measurements of reactor-, geo- and solar neutrinos: MEXT 5 -year project from 2005 300 180 km Kam. LAND-II

2. Prospects of Solar Neutrino Detection single events in Kam. LAND 10 -5 ~ 10 -6

distillation test bench Test Bench Studies 212 Pb 222 Rn R~10 -2 222 Rn : 4 x 10 -3 >R > 5 x 10 -4 85 Kr : 4 x 10 -5 >R > 5 x 10 -6 N 2 purge test bench

Background Reduction Status impurities 238 U present (3. 5 ± 0. 5) x 10 -18 g/g 232 Th (5. 2 ± 0. 8) x 10 -17 g/g 40 K < 2. 7 x 10 -16 g/g 85 Kr ~ 1 Bq/m 3 210 Pb ~ 10 -20 g/g goal reduction 10 -16 g/g 10 -18 g/g ~1 m. Bq/m 3 ~10 -25 g/g OK OK 10 -2 10 -6 10 -5 distillation purge < 10 -2 < 10 -5 < 10 -4 < 10 -5 purification system installation : until this July space for new purification system (May 2005)

Expected Energy Spectrum in Kam. LAND-II 100 days data 210 Po 85 Kr events (0. 3 <E< 0. 8 Me. V) / day / fid. (R< 4 m) 7 Be (80) , CNO (16), pep (4) , 85 Kr (8), 210 Bi (<2), 210 Po (<1), 40 K (3)

Seasonal Flux Variation of Solar Neutrinos 3 years data in Kam. LAND-II events (0. 3 <E< 0. 8 Me. V)/ day / fid. (R < 4 m) 7 Be (80) , CNO (16), pep (4) , 85 Kr (8), 210 Bi (<2), 210 Po (<1), 40 K (3)

Possibility to Detect CNO and pep Neutrinos CNO+pep

11 C Identification DL < 50 cm along m : # of neutrons > 0 11 C with DR < 150 cm Present Kam. LAND Data Dt (DR : distance from the nearest n) 100 200 (min. ) energy 1. 2 1. 4 1. 6 1. 8 (Me. V) DR 200 400 600 800 (cm)

New Electronics for Identifying Successive Multiple Events new (dead-time free)

Expected Energy Spectrum in CNO+pep Region 90% rejection of 11 C 3 years data 7 Be pep CNO 11 C

background subtracted 7 Be neutron tagging efficiency ~ 100% 3 years data CNO pep

3. Toward Precise Measurement of Reactor Neutrinos ( ne nx : 2 -flavor case ) shape-analysis Nobs – NBG Nexpected LMA II: disfavored at 98. 0% CL LAM I = 0. 686 ± 0. 044 (stat) ± 0. 045 (syst) disappearance: 99. 995 % CL LAM 0: disfavored at 97. 5% CL

Improvement of Detector Systematic Error energy scale, timing, g detection, n capture time, n detection, trigger efficiency, light transport, …. 6. 5 % 4 % total uncertainty g n 12 N, 12 B, … m radioactive sources, laser system, LEDs, cosmic-ray m, m –induced spallation products : 1. 012 Me. V (g +System g) Off-Axis Calibration 65 68 Ge Zn : 1. 116 Me. V (g) 60 Co : 2. 506 Me. V (g + g) Am. Be : 2. 20 , 4. 40, 7. 6 Me. V (g)

Setting Off-Axis System

Updated Oscillation Parameters statistics x 5 systematic error : 4% statistics x 5 statistics x 10 systematic error : 4% statistics x 10 limit due to 4% systematic error

4. More and More Geoneutrinos ne ne ne G. Gamow: 1953 ne ne

Geoneutrino Result in Kam. LAND Background Kam. LAND Accidental Coincidence Events/0. 17 Me. V 13 C (a, n) 16 O Reactor ne short lived long lived Th U Antineutrino Energy (Me. V) Total signal # of events 2. 38 ± 0. 01 42 ± 11 best fit 80. 4 ± 7. 2 1. 9 ± 0. 2 127 ± 13 152

Constraints on FU +FTh & FU /FTh in Kam. LAND-II Th/U~3. 9 NU + NTh CL 68. 3% CL 95. 4% CL 99. 7% BSE model best fit (NU – NTh)/(NU + NTh) 2 years data in Kam. LAND-II

2 years data in Kam. LAND-II Th/U~3. 9

Conclusions Kam. LAND-II provides • high rate detection of 7 Be solar neutrinos, • chance to detect CNO + pep solar neutrinos, • stringent constraint on Dm 2 for reactor neutrinos, • more constraint on U+Th (geoneutrinos), and • interesting test of U/Th (geoneutrinos)