Status and Prospects of KamLAND 1000m KamLAND BO 50% dodecane - PowerPoint PPT Presentation

Kunio Inoue Research Center for Neutrino Science, Tohoku University Windows to new paradigm in particle physics, 14-16 February 2005, Sendai, Japan Status and Prospects of KamLAND

1000m KamLAND BO 50% dodecane long. 137 ◦ 18 � 43 . 495 �� lat. 36 ◦ 25 � 35 . 562 �� 50% isoparaffin alt. 358 m ρ LS = 1 . 0004 ρ BO LS CH 3 CH 3 1200 m 3 LS 20 m � HHHHHHHHHHHH 1325 17”-PMTs HCCCCCCCCCCCCH + � HHHHHHHHHHHH CH 3 80% 20% 554 20”-PMTs N (since Feb 2003) O 1.5g/l photo-coverage 22% --> 34% ρ = 0 . 78 g / cm 3 8000 photons / MeV 1800 m 3 ∼ 500 p . e ./ MeV λ ∼ 10 m Buffer Oil 3200 m 3 Water Cherenkov Outer Detector

Various Physics Targets with wide energy range 0.4 1.0 2.6 8.5 Visible energy [MeV] neutrino electron elastic scattering ν e + p → e + + n ¯ inverse beta decay ν + e − → ν + e − supernova relic neutrino geo-neutrino reactor neutrino 7 Be solar neutrino etc. Neutrino Astrophysics Neutrino Geophysics Neutrino Physics Neutrino Cosmology verification of SSM verification of earth Precision measurement verification of evolution model of oscillation parameters universe evolution future forthcoming 1st results Solar ¯ ν e 2nd phase PRL 90, 021802 (2003) PRL 92, 071301 (2004) 2nd results hep-ex/0406035

Reactor neutrino detection ∼ 2 × 10 20 ¯ ν e / GW th / sec ν e ~99.999% ( E > 1 . 8 MeV) ¯ E th = ( M n + m e ) 2 − M 2 235 U : 201 . 7 , 238 U : 205 . 0 , 239 Pu : 210 . 0 , 241 Pu : 212 . 4MeV p = 1 . 806 MeV M.F.James, J.Nucl.Energy 23(1969)517 2 M p neutrinos/MeV/fission ν e + p → e + + n ¯ 1 prompt signal -1 10 e + + e − → 2 γ E vis ∼ E ν − 0 . 78 MeV 238 U > 1 . 022 MeV -2 τ ∼ 210 µ sec 10 theoretical 744 traces n + p → d + γ (2 . 2 MeV) P .Vogel et al., Phys. Rev. C24(1981)1543 235 U -3 delayed signal 10 239 Pu σ (¯ ν e p) is calculable at 0.2% accuracy. P .Vogel and J.F.Beacom, Phys.Rev.D60(1999)053003 -4 10 A.Kurylov et al., Phys.Rev.C67(2003)035502 241 Pu with a help of inverse reaction n → p + e − + ¯ ν e measured at ILL -5 10 tot = 2 π 2 /m 5 0 1 2 3 4 5 6 7 8 9 10 30 hypothetical beta fit σ (0) e E (0) e p (0) Energy (MeV) e f R K.Schreckenbach et al., Phys.Lett.B160(1985)325 p . s . τ n A.A.Hahn et al., Phys.Lett.B218(1989)365 τ n = 885 . 7 ± 0 . 8 sec

Neutrino oscillation study with spread reactors 70 GW (7% of world total) is generated a t 130-220 km distance from Kamioka. ∼ 6 × 10 6 / cm 2 / sec Reactor neutrino flux, ~95.5% from Japan (2nd result period) ~3.5% from Korea effective distance ~180km (weighted average by event rate up to 400 km) from 2006 LMA parameters

A typical 1.3GWe class BWR in Japan 19 Data provided according to the special agreement between x10 Tohoku Univ. and a Japanese nuclear power reactor operator. 8 8 fission/s) U235 Burn-up is calculable from Pu239 7 7 U238 history of thermal power, Pu241 6 6 19 Fission rate (10 fraction of new fuel and 235 U 5 5 enrichment. 4 4 3 3 235 U : 239 Pu : 238 U : 241 Pu = 2 2 1 1 0 . 563 : 0 . 301 : 0 . 079 : 0 . 057 0 0 (average over second result period) 3/3 1/30 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2002 2003 Date Ratio of the fission flux for each isotope at KamLAND 9 x10 Data provided according to the special agreements between 7000 Tohoku Univ. and Japanese nuclear power reactor operators. 1.2 1.2 ) ) 2 2 Ratio of fission flux /day)/(MW/cm fission/cm 6 6000 1 1 day U235 2 10 2 event/cm 5000 Pu239 0.8 0.8 12 235 U 10 U238 Fission number flux(10 4 4000 Pu241 -21 Event rate flux per thermal power flux(10 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.6 0.6 Ratio of the fission flux 3000 239 Pu 0.4 0.4 2 2000 238 U 0.2 0.2 1000 241 Pu 0 0 0 0 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 3/7 1/23 0 100 200 300 400 500 600 700 800 900 1000 2002 2003 Date Distance(km)

Neutrino flux (1.8-8MeV) at KamLAND from reactors 11 Data provided according to the special agreements between x10 Tohoku Univ. and Japanese nuclear power reactor operators. 12 1.2 /day) Total Wakasa-bay Kashiwazaki 2 10 1 neutrino/cm Others Shika Hamaoka 8 0.8 Korea 6 0.6 10 Neutrino flux (10 4 0.4 2 0.2 0 0 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 3/7 1/23 2002 2003 Date 95.5% Detailed information from Japanese reactors 3.4% History of electric power output from Korean reactors 1.1% Nominal power from the other reactors

1st result Data Summary 1.4 N obs /N no_oscillation from March 4 to October 6, 2002 1.2 145.1 live days, 162 ton-year exposure 1.0 0.8 Analysis threshold 2.6 MeV ILL 0.6 Savannah River 86 . 8 ± 5 . 6 expected signal Bugey Rovno 1 ± 1 0.4 Goesgen BG Krasnoyarsk Palo Verde 0.2 observed 54 Chooz KamLAND 0.0 Neutrino disappearance at 99.95% CL. 10 1 10 2 10 3 10 4 10 5 Distance to Reactor (m) R = 0 . 611 ± 0 . 085(stat) ± 0 . 041(syst) KamLAND collaboration, Phys.Rev.Lett.90(2003)021802 Evidence for reactor neutrino disappearance

2 gen. Neutrino oscillation parameters with KamLAND rate consistent with each solar results 10 -3 � m 2 in eV 2 LMA Cl LMA 10 -4 10 -5 SMA SMA 10 -6 SNO 10 -7 SuperK Ga LOW LOW 10 -8 10 -9 RSFP RSFP 10 -10 FCNC FCNC VAC VAC decay decay 10 -11 decoherence decoherence etc. etc. 10 -12 10 -4 10 -3 10 -2 10 -1 10 2 1 10 tan 2 ( � ) Reactor neutrino disappearance excluded all but LMA from leading phenomena.

Analysis Improvements Fiducial volume was enlarged thanks to more uniform energy scale and less vertex bias. 5m --> 5.5m factor 1.33 Coincidence criteria were loosened to increase detection efficiency focusing on reactor neutrinos. 78.3% --> 89.8% factor 1.15 And more run time.

X 3.55 live time 24 600 LiveTime [day] hour 22 20 500 18 1st result 16 400 4 Mar 2002 - 6 Oct 2002 14 145.1 days 12 300 2nd result 10 9 Mar 2002 - 11 Jan 2004 8 200 515.1 days 6 4 100 2 0 0 02 03 04 05 06 07 08 09 10 1112 01 02 03 04 05 06 07 08 09 10 1112 01 2002 2003 2004 Physics Run Calibration Run (source,laser and LED) Test/Bad Run

Finally, lower reactor operation X 0.77 1.2 210 Weighted distance(km) (events/day) exp Period for first result N no-oscil Weighted distance 1 200 no-oscil exp 0.8 190 N 0.6 180 0.4 170 0.2 160 0 150 Jul/02 Jan/03 Jul/03 Jan/04 Statistical improvement --> X 4.2

Energy Calibration with Radioactive Sources with Muon Spallation 5 10 n+p → D+ γ 4 10 3 10 n+ 12 C → 13 C+ γ z-axis dependence of energy 2 10 5 12 B etc. deviation of E[%] Co 10 4 Zn Zn 1 Ge 3 0 2 4 6 8 10 12 14 16 2 Energy (MeV) 3 deviation[%] 1 spallation neutron 2 (proton capture) 0 1 -1 0 -2 -1 -3 -2 -4 -5 -3 -600 -400 -200 0 200 400 600 Mar Apr May Jun Jul Aug Sep z-axis[cm]

2500 1 68 Ge 65 Zn 12 B/ 12 N 60 Co 2000 0.8 12 C n- n-p 1500 0.6 0.4 1000 0.2 500 0 0 0 3 5 1 2 4 12 14 16 4 6 8 10 visible energy (MeV) visible energy (MeV) E ∼ 6 . 2% σ ∼ 7 . 5% → ∼ 7 . 3% with 20” PMTs √ E without 20” PMTs 0.04 γ -ray sources β decay Energy scale error at 2.6 MeV n-p Cherenkov/Birks 1.0% 0.02 12 68 n- C Ge 60 Co E/E 12 12 B/ N Time dependence 1.3% 0 ∆ Position dependence 1.0% 65 Zn -0.02 20” PMT non-linearity 0.8% -0.04 Total 2.0% 0 1 2 3 4 5 6 7 8 9 Energy (MeV)

Fiducial Volume Calibration with Radioactive Sources with Muon Spallation 4000 12 B 3500 10 Co Ge Am/Be(4.4MeV) z deviation[cm] 3000 Zn Am/Be(~7.6MeV) Events/Bin 5 balloon 2500 radius 2000 0 1500 1000 -5 fiducial 500 -10 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 -600 -400 -200 0 200 400 600 z-axis[cm] 3 (R/6.5m) σ x,y,z ∼ 20cm 1000 with 20” PMTs p(n , γ )d √ E 800 balloon 600 radius Fiducial/Total Volume Ratios 400 200 fiducial � 696 . 9 m 3 � geometrical 0 . 595 ± 0 . 013 = 0 1171 ± 25 m 3 0 0.2 0.4 0.6 0.8 1 1.2 1.4 3 (R/6.5m) 12 B prompt R - delayed R [cm] 150 0 . 607 ± 0 . 006 ± 0 . 006 fiducial delayed 9 Li 100 coincidence p(n , γ )d 50 0 . 587 ± 0 . 013 β + n 0 9 Li relative < 2 . 7% -50 -100 8 9 He Li (prompt energy>4MeV) conservative volume error 4.7% -150 0 0.2 0.4 0.6 0.8 1 1.2 3 (delayed R/6.5m)

So far Achieved Systematic Errors Systematic % Fiducial volume 4.7 Energy threshold 2.3 Efficiency of cuts 1.6 Livetime 0.06 Reactor power 2.1 Fuel composition 1.0 ν e spectra 2.5 Cross section 0.2 Total 6.5

Event Selection prompt delayed coincidence 8 6 0 . 5 < ∆ T < 1000 µ sec (660 µ sec) 4 (1 . 6 m) ∆ R < 2m 2 z (m) 1 . 8 < E delayed < 2 . 6 MeV (neutron capture) 0 fiducial volume -2 R prompt , delayed < 5 . 5m (5 . 0 m) -4 -6 (408 . 5 ton) 543 . 7 ton N p = 4 . 61 × 10 31 (3 . 46 × 10 31 ) -8 0 5 10 15 20 25 30 35 40 45 50 2 2 2 x +y (m ) spallation cuts delayed 8 ∆ T µ < 2msec 6 E extra > 3GeV ∆ T µ < 2sec (showering) 4 or ∆ L < 3m 2 z (m) 0 dead time 9.7% (11.4%) -2 reactor energy window -4 2 . 6 < E prompt < 8 . 5 MeV -6 -8 0 5 10 15 20 25 30 35 40 45 50 Total detection efficiency 89.8% (78.3%) 2 2 2 x +y (m )