Background study for solar neutrino measurement in ... - LRT2006

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Background study for solar neutrino measurement in ... - LRT2006

SK


SK


ν

LMA sin 2 (θ)

0.22

0.28

0.35


0



Data/SSMBP2004

MeV


β



Remove Rn(gas)

Remove Ra(particle)

Circulation 35t/h

0.4mBq/m 3

< 2mBq/m 3


eturn

water

urified

ater

Z -5m

Rn Rn

Rn

Rn Rn

Rn

Rn Rn

Z +18m

Z -18m


Rn

Z (m)


eturn

water

urified

ater

Rn Rn

Rn Rn Rn

Z +18m

Z -18m



Rn

Before

Z(m)


After

Z


± ×

± ×

± ×

± ×

± ×

± ×

± ×

± ×


FRP for PMT case

Acyclic cover for PMT

Glass for PMT PMT base with cable

SUS for the Frame

Dust with wiping paper


×

×

×

×

×

×

×

×

×

×

×

×



Normalized to 1PMT

×

×

×

×


208 Tl→ 208 Pb

2.615 MeV(99.2%)

861 keV(12.4%)

583keV(84.5%)

511keV(22.6%)

Lantern mantle

300 pieces


Z

Y

X

Center of the tank

Hole to access behind PMTs


Z

Y

X

Center of the tank

Hole to access behind PMTs


Preliminary


Preliminary

This tail may

invade the

fiducial volume


Preliminary




Preliminary BG subtracted L-M spectrum


Preliminary

4.8MeV and 6MeV electron beams

were irradiated near the L-M source positon


“ ”


以下 しだま


FULL Volume mean, with obsolete fitter


2

“ ”


•Remove radon by (cooled) activated charcoal

Mine air

4m 3 4m 3

flow rate: ~15m 3 /h

~60cm

SK dome

air

water

(2mBq)

50L


Radon concentration in

mine air: ~1000Bq/m 3 (summer)

~40Bq/m 3 (winter)

purified air: 2~3mBq/m 3

air in SK tank: 10~20mBq/m 3

seasonal variation is caused by different

wind direction in mine tunnel


2.6MeV


Preliminary

4.8MeV and 6MeV electron beams

were irradiated near the L-M source positon


Events/kg/keV/day

events/kg/keV/day

10 3

10 2

10

10 -1

1

10 -2

10 -3

10 -4

10 -5

10 -6

10 -7

10 -8

10 -9

10 -10

10 -11

10 -12

DAMA

NaI

XMASS

800kg

1 10 10 2

ZEPLIN before PSD cut

CDMS II

After PID

DM signal for LXe

100GeV 10-6pb

10 3

Kamioka Ge

Current XMASS (new improvement!)

10 4

energy (keV)

Heidelberg Moscow

KamLAND (>0.8MeV)

Super-K

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