Solar neutrino results Kam LAND prospects l l

Solar neutrino results, Kam. LAND & prospects l l l Solar Neutrino History Kam. LAND Prospects Kengo Nakamura Duke/TUNL www. awa. tohoku. ac. jp/~kengo/Nu. Fact 03. pdf 5 th June 2003, Nu. Fact 03 Kengo Nakamura 1

Solar Neutrino Problem 5 th June 2003, Nu. Fact 03 Kengo Nakamura 2

Neutrino Oscillation üCl, Kamiokande, Ga LMA, SMA, LOW, VAC üSuper. K day night, Super. K energy spectrum LMA+LOW SNO NC; e+ m+ t üFlavor transition üSNO day/night àLMA SMA LOW VAC Kam. LAND; Man made neutrino sources 5 th June 2003, Nu. Fact 03 http: //hitoshi. berkeley. edu/neutrino Kengo Nakamura 95%CL 3

SNO result PRL 89(2002)011301 Without the constraint on energy (SSM) direct measurement of active 8 B . l. Strong evidence for neutrino flavor transition. l. Total 8 B agrees with SSM. l. SNO Day/night + All solar LMA. l. First 5 th June 2003, Nu. Fact 03 Kengo Nakamura 4

SNO Status l. Neutron capture on Cl ØLarge s of neutron capture on Cl Ø 8. 6 Me. V multiple s ØGood light isotropy ØBetter NC extraction ØResult is expected in a few months? A. Poon I. O. P. HEPP Particle Physics 2003, Durham l. Installation of Neutral Current Detector Array Øn+3 He p+t ØIndependent NC measurement(syst. +9. 1/-8. 5 +/- 4. 5 %) ØSept. 03 ? 5 th June 2003, Nu. Fact 03 Kengo Nakamura 5

Kam. LAND Kamioka Liquid scintillator Anti Neutrino Detector (Evis ) l l l Reactor Anti Neutrino Source. Energy distortion? under Lab. condition. LMA? CPT invariance. 7 Be neutrinos. 5 th June 2003, Nu. Fact 03 Kengo Nakamura 6

a few /day in Kam. LAND l l 5 th June 2003, Nu. Fact 03 Kengo Nakamura Thermal power, Burn-up, Fuel change record data, Simple model of reactor core. à fission rate à energy spectrum @Kam. LAND Korea(2. 3+- 0. 2% @N( ) ) 7

Kam. LAND Detector 2700 m. w. e. Evis=E -0. 78 Me. V 20 m 5 th June 2003, Nu. Fact 03 Kengo Nakamura 8

Energy resolution ( + ) : 65 Zn ( ) : 60 Co ( + ) : Am. Be ( , n) : n+p d+ : n+12 C 13 C+ : 68 Ge E/E ~ 7. 5% /√E [Me. V] l Esyst=1. 9% at 2. 6 Me. V 2. 1% for anti e l 5 th June 2003, Nu. Fact 03 Kengo Nakamura 1. 012 Me. V 1. 116 Me. V 2. 506 Me. V 2. 20, 4. 40, 7. 6 Me. V 2. 2 Me. V 4. 9 Me. V n m spallation 9

Am. Be Neutrons 660 msec Capture time = 190 msec Delayed coincidence effi = 95. 3 % 5 th June 2003, Nu. Fact 03 Kengo Nakamura Detection effi= 98. 8% 10

Vertex reconstruction 5 cm resolution Uniform 2. 2 Me. V 4. 1% uncertainty on number of neutrinos coming from fiducial mass ratio 5 th June 2003, Nu. Fact 03 Kengo Nakamura 11

214 Bi – 214 Po – 210 Pb Signal prompt 238 U delayed = (3. 5± 0. 5)x 10 -18 g/g b+ DT = |tprompt – t delayed| t= t (214 Po: a) a = 237 ms 5 th June 2003, Nu. Fact 03 Kengo Nakamura 12

Radioactive Background in LS 5 th June 2003, Nu. Fact 03 Kengo Nakamura 13

5 th June 2003, Nu. Fact 03 Kengo Nakamura 14

Neutrino Event selection Details l. Timing correlation in PMTs lno m veto signals l 0. 5 < T < 660 msec l 1. 8 < Edelayed< 2. 6 Me. V l. R < 5 m : 409 ton, 3. 46 x 1031 free protons l R < 1. 6 m, Rd > 1. 2 m l. Veto for 2 msec. after muons. l. Veto for 2 sec. after muons (E>106 p. e. ) (0. 02 Hz) l Cylindrical (R=3 m) 2 sec veto around muons (E<106 p. e. ) tagging efficiency 78. 3% 5 th June 2003, Nu. Fact 03 Kengo Nakamura 15

Vertex position after delayed coincidence 5 th June 2003, Nu. Fact 03 Kengo Nakamura 16

Prompt Delayed (n 12 C) 5 th June 2003, Nu. Fact 03 Kengo Nakamura 17

Kam. LAND result Observed Mar. 4 – Oct. 6, 2002 162 ton • yr (145. 1 days) 54 events (E>2. 6 Me. V) Background 1 ± 1 events Expected 5 th June 2003, Nu. Fact 03 86. 8 ± 5. 6 events Kengo Nakamura 18

Kam. LAND impacts 95%CL LMA 2 LMA 1 Kam. LAND 5 th June 2003, Nu. Fact 03 All combined Kengo Nakamura 19

Spectral Distortion? 2 - oscillation: best-fit No oscillation, flux suppression Data and best oscillation fit Data and scaled no-oscillation shape consistent at 53% C. L consistent at 93% C. L. Need more reactor neutrino and calibration data Kengo Nakamura 20 5 th June 2003, Nu. Fact 03

Kam. LAND Prospects • Neutrino Oscillation? Precision measurements – – Energy Spectrum distortion? Current reactor power in Japan ~50%. A new reactor is coming. LMA 1 or LMA 2 • 7 Be – Purification system improvement 5 th June 2003, Nu. Fact 03 Kengo Nakamura 21

c 2 projection LMA II LMA I 5 th June 2003, Nu. Fact 03 Kengo Nakamura 22

LMA I Before and After Shika LMA II 5 th June 2003, Nu. Fact 03 Kengo Nakamura 23

Solar @ Kam. LAND l. No direct observation of 7 Be . l. Improve Kam. LAND purification system. l 210 Pb; 10 -20 g/g 10 -25 g/g (Water extraction) l. Air tight valve housings. l. Testing the water extraction. 5 th June 2003, Nu. Fact 03 Kengo Nakamura 24

Expected 5 th June 2003, Nu. Fact 03 Kengo Nakamura 25

XMASS 5 th June 2003, Nu. Fact 03 Kengo Nakamura 26

l Last year Summary – 8 B neutrino measurement and strong evidence of neutrino flavor transition by SNO. – Kam. LAND observed a clear deficit in reactor neutrinos. • Current Status related to Kam. LAND and SNO – SNO cl results coming soon and new NC detector installation. – Kam. LAND stable n data taking during reactor shutdown. • Future – Kam. LAND update results. – Kam. LAND purification system will be improved for 7 Be Solar neutrino detection. 5 th June 2003, Nu. Fact 03 Kengo Nakamura 27

Backup slides 5 th June 2003, Nu. Fact 03 Kengo Nakamura 28

How to calculate neutrino flux from reactors 5 th June 2003, Nu. Fact 03 Kengo Nakamura 29

Solar Neutrino at Kam. LAND 5 th June 2003, Nu. Fact 03 Kengo Nakamura 30

Matter effect 5 th June 2003, Nu. Fact 03 Kengo Nakamura 31

q 13 The Kam. LAND is actually measuring; 5 th June 2003, Nu. Fact 03 Kengo Nakamura 32

Trigger efficiency 5 th June 2003, Nu. Fact 03 Kengo Nakamura 33

5 th June 2003, Nu. Fact 03 Kengo Nakamura 34

c 2 projection 5 th June 2003, Nu. Fact 03 Kengo Nakamura 35