General performance of the IceCube detector and the calibration results Mina Inaba 1 S.Yoshida 1,...
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Transcript of General performance of the IceCube detector and the calibration results Mina Inaba 1 S.Yoshida 1,...
General performance of General performance of the IceCube detectorthe IceCube detector
and and the calibration results the calibration results
Mina InabaMina Inaba11 S.YoshidaS.Yoshida1 1 , K.Mase, K.Mase11, C.Rott, C.Rott22 ,Y.Hasegawa ,Y.Hasegawa11
1.Dept. of Physics, Chiba University1.Dept. of Physics, Chiba University2. Pennsylvania State University2. Pennsylvania State University
for the IceCube Collaborationfor the IceCube Collaboration
PD 07 @ Kobe Univ. 06/29/2007
Outline
• Introduction of the IceCube experiment• General performance of the IceCube detector• PMT/DOM Production Procedure• Calibration of PMT• Calibration of DOM• Comparison between PMT and DOM• Detector status in the ice• Summary and future work
South pole
IceCube
1 km
The IceCube experiment
~1 km
AMANDA-IIIceCube
1km3
IceTop
〜 1 km
1450m
2450m
• Cherenkov light detector
• 60 PMTs x >70 strings = >4200 PMTs
• Neutrino energy of 107(SNs)-1020eV is detectable.
• 22 strings are deployed up to now, and taking data as the biggest neutrino detector.
Module of the IceCube
PMT HV Base Board
Flasher board
Magnetic Shield Cage
Optical gel
Glass Pressure Sphere
Onboard capture of PMT waveforms
• - ATWD : 300MHz 14 bits (~400nsec) 3 different gains (x16, x2, x0.25)• - FADC : 40MHz 10 bits (~6.4μsec)
Digital Optical Module (DOM)
35.6cm
10inch R7081-02 PMT
Hamamatsu
Typical digitized waveform
General performances of the PMT
Dynamic range
•Type R7081-02 (bialkali)•Dynode 10 stages•Quantum efficiency 25% @420nm•Dynamic range 1000p.e. /30nsec @107 gain•Time resolution 2.2nsec•Noise rate 300Hz @ -40 ~ -20℃ ℃•Operation gain 1x107 @1300V
Noise rate QE
p.e.103temp
Dar
k co
unt
Cha
rge
[pC
]
Wavelength [nm]
QE
xCE
25%300Hz
Main board
metal cage Flasher board
Optical gel
HV board
10 inch PMT
DOMPMT
Normal checkNormal check: Linearity of the PMT gain dark noise rate charge resolution2D sensitivity scan
Golden PMTsGolden PMTs:
normal check + Absolute calibrationAbsolute calibration
Hamamatsu Chiba Univ. Wisconsin Univ. Chiba Univ. South Pole
assembles DOMs
check all DOMs (under low temperature)
Linearity of the DOM gain dark noise rate component check cold reboot communication test
Golden DOMsGolden DOMs: 2D sensitivity scan Absolute calibrationAbsolute calibration
Production Procedure
Freezer -32℃
Set up of SPE measurement
Diffuser attached to the UV LED
375nmUV LED
In the Freezer box
2kHz, ~0.01 photo-electron/shot
2( )
The parameterization of SPE CR
The exponential term Comes from an
incomplete multiplication at the first dynode
Fitted the spe charge response
with 1 exponential
+ 1 gaussian terms.
The averaged charge response
Average over 118 PMTs
One measurement
Mean 15% lessMean 15% less
Peak of gaussian Peak of gaussian ~ 1 p.e.~ 1 p.e.
Charge resolution 29%
Absolute calibration of PMT
5x10-11
337nm N2
laser Energy meter
Rayleigh scattering
4x109
Cathode hit photon#
~0.2
QE=Photoelectron#
Energy meter Numerical calculation
Cathode hit photon#
x
Rayleigh scattering cross section is well understood
Using Rayleigh scattering
Results of absolute calibration
Our data havea good correlation with Hamamatsu
QE measured by Hamamatsu(340nm)%
Systematic error
Photoelectron# : 1%Light yield : 4%Initial photon fluctuation : 4 %Pressure : 1%Photon energy probe : 5%Total ~8%
PMT 2D Uniformity ScanAveraged PMT
2D CEMap(~94PMTs)
LED
motor
PMT
The direction of the first dynode
Efficiency depends on the cathode surface.
2D CE combined with QExCE
Absolute efficiency
We can draw Absolute
2D QExCE Map !
2D Collection efficiency
Map
CE Map normalized to QE
Length on cathode [m]
Eff
icie
ncy[
%]
17.8%
18.1% 15.5%
16.0% 18.7%
15.0% 16.7%
17.9%
TA1895 TA2026
TA2086 TA2146 TA2182
TA2259 TA2349
TA2374
Systematic error ~ 8%
20
0-0.15m 0.15m
@337nm
2D QE x CE Map of PMT
Variance of the Collection efficiency0°90°
Variation of the collection efficiency
~ 15%
90° 0°
By. Y.Hasegawa
Length on cathode [cm] Length on cathode [cm]
QE
xCE
[%]
QE
xCE
[%]
Digital Optical Module = DOM
PMT Absolute Calibration
Glass + Gelmeasurement
DOM Absolute Calibration
Reminder …what is a DOM ?
PMT
GelGlass
DOM
Reference PMT Absolutely calibrated
NDfilterLED
Slit 1mm
X-stage
QE×CE Absolute calibration 4πCE scanning
LED
Systematic error ~7% @ room
Calibration of DOM
Reflectivity : 14.5%±0.73Transmission : 50.7%±2.54
By. Y.Hasegawa
15.3%14.0% 15.4% 16.3%
17.5% 16.6% 18.0% 16.0%
TA1895 TA2026TA2259 TA2349
TA2086 TA2146 TA2182 TA2374
Systematic error ~ 7%
18
0-0.3m 0.3m
@365nm
2D QE x CE Map of DOM
Comparison between PMT and DOM
PMT Calibration Transparency of glass/gel
DOM Calibration
Comparison
PMT + Glass/Gel
Wavelength [nm]
Comparison between PMT and DOM
Good agreements over the wavelengths.
337nm8.21%
365nm16.1%
520nm10.7%
572nm4.99%
DOM
NDfilter
LED
Absolute calibration of DOM
PMT + Glass/Gel
470nm17.5%
Detector status
gain
HV
Variation ~2.5%
Mean : 1.0 x 107
Variation ~7%Mean :1285V
Temperature
stri
ng
Shallow ← depth → deep
rate
IceCube is now working IceCube is now working smoothly!! smoothly!!
UTC Time
4.5Hz
-30℃ -10℃
700Hz
Summary
• General performances of the IceCube PMT were shown.
• Averaged charge response and 2D CE map over 100 PMTs are derived. We have implemented the fundamental characteristics of our detector into the detector simulation.
• We measured absolute efficiency of our PMTs. Our measurement has a good correlation with Hamamatsu.
• We compared between PMT+ Glass/Gel and DOM. It showed good agreement over the wavelength.
• IceCube is now taking data smoothly.
130.04m
Golden DOMAbsolute Calibrated detector
Standard CandleCalibrated N2 laserCone reflected light
Future workAbsolute Calibration in the iceAbsolute Calibration in the ice
Thank you !Thank you !
Backup Slides
Summarized by Y. Hasegawa
Charge resolution(sq0/q0)
Decay time (qtau/q0)
Exponential/SPE(P_ex)
Obtained Parameters
0.51±0.016 0.30±0.01 0.29±0.01
Many PMTs failed to fit at low gain
Total 118PMTs (FY2004~2006)
statistics is enough to picture average behavior !!
19.8%17.6%
17.8%16.7%
12.2%11.3%
5.28%4.29%
Keno_Inuzaka(TA1056) Daikaku_Inumura(TA1176)
18.0%17.0%
16.2%13.5%
11.5%10.5%
5.08%4.65%
17.3%14.4%
14.3%15.4%
9.89%9.66%
4.58%4.05%
Red : measured at 24℃Blue : measured at -32℃
QE measured at -32℃ was 5~10% lowerlower than measured at 24℃
Sosuke_Inukawa(TA1181)
QE measurement at -32℃
After pulses
Original pulse
After pulses
•show around 600nsec 2 μsec 8μsec•Peak 13SPE(600nsec)•Rate Hz
ここに測定について載せる予定です
Chiris からの返事待ち
The various peaks are believed to correspond to ions of different mass
@1x107 @5x107
@1x108
Charge Response @different gains
pedestalSPE