J. Vandenbroucke

N. Bramall, M.D’Agostino, A. Morey, P. Sandstrom, M.Solarz, I.Taboada

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Calibration of the Standard Candle:How Standard Is It?

IceCube Collaboration Meeting, Baton Rouge, April 10, 2006

J. Vandenbroucke Baton Rouge April 10, 2006

Motivation

• An IceCube calibration source whose absolute intensity is known precisely for each pulse

• Extend the flasher energy range to cover IceCube’s high end

• Simulate high energy cascades to test cascade energy and direction reconstruction

• Combine with Golden DOM’s for a complete well-calibrated chain

J. Vandenbroucke Baton Rouge April 10, 2006

Components

Pressure VesselOptics

Laser

Electronics

J. Vandenbroucke Baton Rouge April 10, 2006

Laser

Heating Tape

Nitrogen Laser 337 nm 4 ns pulse 30 Hz internal power meter adjustable filter wheel

J. Vandenbroucke Baton Rouge April 10, 2006

Optics Design

Optics Implementation

Cherenkov-Sculpting ConeCerenkov-Sculpting Cone

J. Vandenbroucke Baton Rouge April 10, 2006

Software

Data Stream:•pulse number•mSec timestamp: pmt•mSec timestamp: laser•internal power•pmt DAQ dark current•pmt DAQ actual current•pmt DAQ temperature

J. Vandenbroucke Baton Rouge April 10, 2006

The First Standard Candle

Deployed on String 40Between 40-22 and 40-23

J. Vandenbroucke Baton Rouge April 10, 2006

The First Standard Candle

Deployed on String 40Between 40-22 and 40-23

J. Vandenbroucke Baton Rouge April 10, 2006

Calibration Specifics: Optics

€

ηcone = 8.0 ±1.0%

We can “bypass” the extinctionin the optics by using an absolutecalibration of the PMT and thelaser’s internal power meter

€

ηwindow ≈ 8% (prelim.)

Extinction due to cone:

Extinction due to window:

J. Vandenbroucke Baton Rouge April 10, 2006

Calibration Specifics: Obstructions

1) main cable

2) support vanesfor cone

3) steel supportcables

obstructions not aligned sum extinctions

J. Vandenbroucke Baton Rouge April 10, 2006

Calibration Specifics: Obstructions1) main cable

€

ηbent = 5.5%

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ηstraight = 5.0%

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∴ηmain cable = 5.25−0.25+0.25%combine two cases

Extinction due to main cable:

J. Vandenbroucke Baton Rouge April 10, 2006

Calibration Specifics: Obstructions2) cone support vanes

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€

ηvanes = 4.34%Extinction due to vanes:

J. Vandenbroucke Baton Rouge April 10, 2006

Calibration Specifics: Obstructions3) steel support cables

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ηsteel cables = 2.4%Extinction due to steel cables:

J. Vandenbroucke Baton Rouge April 10, 2006

Two independent, calibrated internal energy measurements: PMT & power meter

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ELASER = rEpower meter

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EPMT

• Plot not available (en route from Pole)• PMT calibrated for filter wheel settings 50% and 5% (calibration to +/- 10%)

(1)

(2)

J. Vandenbroucke Baton Rouge April 10, 2006

Calibration Conclusions

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χ =(1−η cone) * (1−η window ) * (1−η vanes −ηmain cable −η steel cables)

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E = χEPMT

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E = χELASERand

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χ =0.74−.01+.06

E@50% ≈1.67−.03+.11 μJ

NMIN ≈ 4.75−.03+.40 *1010

NMAX ≈ 5.26−.15+.36 *1012

Preliminary Calibration:

Total extinction:

Per-pulse Energy:

For details, see Standard Candle Calibration and other SC documents:http://docushare.icecube.wisc.edu/docushare/dsweb/View/Collection-1152

The Future: Burning Brightly

More to come from the Standard Candleshop• Next year: point down (between DOM’s 12 and 13), 20x brighter

• Later: point sideways (with cone removed?)