Optical Sensor and DAQin IceCube

Albrecht KarleUniversity of Wisconsin-Madison

karle@amanda.wisc.edu

ChibaJuly, 2003

Outline

• Events signatures and their requirements on DAQ.

• The design of the optical sensor for IceCube.

• A brief construction status.

The IceCube Collaboration

Institutions: 11 US, 9 European institutions and 1 Japanese institution; ≈150 people 1. Bartol Research Institute, University of Delaware2. BUGH Wuppertal, Germany3. Universite Libre de Bruxelles, Brussels, Belgium4. CTSPS, Clark-Atlanta University, Atlanta USA5. DESY-Zeuthen, Zeuthen, Germany6. Institute for Advanced Study, Princeton, USA7. Dept. of Technology, Kalmar University, Kalmar, Sweden8. Lawrence Berkeley National Laboratory, Berkeley, USA9. Department of Physics, Southern University and A\&M College, Baton Rouge, LA, USA10. Dept. of Physics, UC Berkeley, USA 11. Institute of Physics, University of Mainz, Mainz, Germany12. University of Mons-Hainaut, Mons, Belgium13. Dept. of Physics and Astronomy, University of Pennsylvania, Philadelphia, USA14. Dept. of Astronomy, Dept. of Physics, SSEC, University of Wisconsin, Madison, USA15. Physics Department, University of Wisconsin, River Falls, USA16. Division of High Energy Physics, Uppsala University, Uppsala, Sweden17. Fysikum, Stockholm University, Stockholm, Sweden18. University of Alabama19. Vrije Universiteit Brussel, Brussel, Belgium20. Dept. of Physics, niversity of Maryland, USA21. Chiba University, Japan

IceCube

1400 m

2400 m

AMANDA

South Pole

IceTop

Skiway

• 80 Strings• 4800 PMT • Instrumented

volume: 1 km3 (1 Gt)

Track reconstruction in low noise environment

• Typical event: 30 - 100 PMT

fired• Track length: 0.5 - 1.5 km• Flight time: ≈4 µsecs • Accidental noise pulses:

10 p.e. / 5000 PMT/4µsec• Angular resolution: 0.7 degrees• Effective muon detector area: 1 km

(after background suppression)

AMANDA-II

1 km

10 TeV

Point sources: event rates

AtmosphericNeutrinos

AGN* (E-2) Sensitivity(E-2/(cm2 sec GeV))

All sky/year(after quality cuts)

100,000 -

Search bin/year 20 2300 -

1 year: Nch > 32 0.91 610 5.3 x 10-9

3 year: Nch > 43 (7 TeV)

0.82 1370 2.3 x 10-9

Flux =dN/dE = 10-6*E-2/(cm2 sec GeV)equal to AMANDAB10 limit

Point source sensitivity

10-10

10-8

10-6

10-4

102 103 104 105 106

E2

(dN/dE ) [GeVcm

-2s

-1]

Eν( )GeV

- (3 )AMANDA II yr

- 10 ( 97)AMANDA B '

IceCube3 273C

Crab

AGN Core

501 (Mk ν=γ)

. Atm ν

IceCube 3 years

(1yr)

The sensitivity of IceCube to an E^-2 neutrino spectrum

is comparable to the sensitivityof GLAST to an E^-2 photon

spectrum

Cascade event

Energy = 375 TeV

νe + N --> e- + X

•The length of the actual cascade, ≈ 10 m, is small compared to the spacing of sensors•==> ≈ roughly spherical density distribution of light

1 PeV ≈ 0.5 km diameter

ν Double Bang

ν + N --> - + X

ν + X (82%)

E << 1PeV: Single cascade (2 cascades coincide)E ≈ 1PeV: Double bangE >> 1 PeV: partially contained (reconstruct incoming tau track and cascade from decay)

Regeneration makes Earth quasi transparent for high energie ν;(Halzen, Salzberg 1998, …)Also enhanced muon flux due to Secondary µ, and νµ

(Beacom et al.., astro/ph 0111482)

Learned, Pakvasa, 1995

Density profile of double bang event

-300 m 300 m0 m

300 m

0 m

Shown is the expected photoelectron signal density of a tau event.The first ν interaction is at z=0, the second one at ≈225m.The diagram spans about 400m x 800m.

Pho

toel

ectr

ons/

PM

T

10

105

103

10-1

Capture Waveform information

• Complex waveforms provide additional information

E=10 PeV

0 - 4 µsec

Events / 10 nsec

String 1 String 2 String 3 String 4 String 5

Observed waveforms in IceN2-Laser event generated by in situ laser:Amplitude: ≈ 10^10 photons, Wavelength: ≈ 335 nmPulse width: ≤ 10 nsec

- comparable to ≈300 TeV cascade

2 µsec

SimulationData45 m

115 m

167 m

Distance of OM

*

*HV of this PMT was lowered

Eµ=10 TeV ≈ 90 hits Eµ=6 PeV ≈ 1000 hits

Energy reconstructionSmall detectors: Muon energy is difficult to measure because of fluctuations in dE/dx IceCube: Integration over large sampling+ scattering of light reduces the fluctutions energy loss.

Design goals

• IceCube was designed to detect to neutrinos over a wider range of energies and all flavors.

• If one would wish to build a detector to detect primarily PeV or EeV neutrinos, one would obviously end up with a different detector.

Neutrino flavorνμννe ( / )Log ENERGY eV1218156219νe

Eµ=10 TeV ≈ 90 hits Eµ=6 PeV ≈ 1000 hits

A remark on the side for EeV fansThe typical light cylinder generated by a muon of 1E11 eV is 20 m, 1EeV 400 m, 1E18 eV it is about 600 to 700 m. This scaling gives a hint of how one could design a E>EeVoptimized geometry in ice could be. (String spacing ≈ 1 km)

DAQ design: Digital Optical Module- PMT pulses are digitized in the Ice

Photomultiplier

Design parameters:• Time resolution:≤ 5 nsec

(system level)• Dynamic range: 200

photoelectrons/15 nsec• (Integrated dynamic range: >

2000 photoelectrons)• Digitization depth: 4 µsec.• Noise rate in situ: ≤500 Hz

33 cm

DOM

For more informationon the Digital Optical Module:see poster by R. Stokstad et al.

Assembled DOM

Photomultiplier: Hamamatsu R7081-02

(10”, 10-stage, 1E+08 gain)

• Selection criteria (@ -40 °C)• Noise < 300 Hz (SN,

bandwidth)• Gain > 5E7 at 2kV (nom.

1E7 + margin)• P/V > 2.0 (Charge res.; in-situ gain calibration)

• Notes:• Only Hamamatsu PMT

meets excellent low noise rates!

• Tested three flavors of R7081.

DAQ Network

architecture

McParland et. al. -- A Preliminary Proposal for the IceCube DAQ System Architecture -- DRAFT7

DOMPair20 kB/sec

StringProcessor

N x 20 kB/sec

.

All Hits -0.6 MB/sec

80 Strings

String Subsystem:60 DOMs

N pairs

Event LAN100 BaseTTotal traffic: 1.6 MB/secStringCoincidenceMessagesGlobalTriggerEvent Triggers /Lookback Requests forall Strings - 0.8 MB/sec

EventBuilderBuilt events ~ 1 MB/sec(all event builders)

SAN(NetworkDisk Storage)

"DOMHUB"

Lookback RequestsString CoincidenceMessages - 170 kB/secFulfill Lookback Messages 0.6 MB/sec FulfillLookbackMessages

Online LAN100 BaseTTotal traffic: 1MB/sec

Proposed IceCube DAQ Network Architecture

String LAN100 BaseTTotal traffic: 0.6 MB/sec

OfflineDataHandlingTapeSatellite

Custom design: 5000 DOMs,

2500 copper pairs, 800 PCI cards

(10 racks)

Off the shelf IT infrastructure, Computers, switches, disks

DAQ SoftwareDatahandling software

Digital Optical Module (DOM) Main Board Test Card

Waveform Capture:

• Dynamic range /sampling rate (first 400 ns): ~ 14 bits @ ~300 MHz “Analog Transient Waveform Digitizer”

• Dynamic range/sampling rate (~ 4000 ns): ~ 10 bits @ 40 MHz FADC is appropriate solution

• PMT noise rate: ~ 500 Hz Data compression/feature extraction needed

Operational parameters (typical)

SPE: 5 mVElectronic noise: <0.2 (0.1) V

Dynamic range: 200 PE/15 nsec1000 PE/4 µsec

Overall noise rate of DOM: 500 - 1000 Hz

Design goals

IceCube String

1400 m

2400 m

60 optical sensors

Main Cable

SensorBase with HV generatorElectrical

feedthrough forpower + data

Glass pressure sphere. Rated to 10000 psi.Outer diameter: 13"

Photomultiplier

Gel

String

OM Spacing: 17 m

The DOM communicates via ≈3km copper wires to the central DAQ

1350 m

2400 m

IceTop

IceCube

Counting

House

Connector

Surface cable:

from Counting Hose

string position.

Includes IceTop OM.

Length specific for each string.

String :

Fixed Length*: 2420 m

*Actual length may change somehwat.

Need to determine the stretch factor.

2 DOMs on one twisted pairBandwidth goal: 1 Mbit/sec

The DOM Receiver (DOR):a PCI Card

Data transmission

• New test cable from Ericsson tested successfully at 1 Mbit/sec.

• Recent e-mail from K.-H. Sulanke (DESY/LBNL) with attached file labeled: “TX0_RX1_no_problem.PDF”

• Figure shows bit sequence before and after transmission over 3.5 km twisted pair.

The DOM Hub (prototype)

Counting room

Preliminary, (30%)

52’ x 28’

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Counting House will be very similar to other buildings at the South Pole.

ARO building, South Pole

Low temperature Laboratoriesand Test facilities

• The Collaboration is building production and test facilities in Europe, US and in Japan.

• Sensors to be tested in large dark freezers. • Production, Verification and initial calibration of

each DOM during extended test periods (months) prior to deployment.

Example of a dark freezer laboratory.

up to 300 DOMs@ -50°C

Production of drill components

The big reel for the hotwater drill

Hotwater Drilling

QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.

• New drill: Faster and more reliable.

• Drilling time to 2000 m depth: 35 h

• (AMANDA: 80h)• Diameter: 50 cm

Picture: AMANDA drill

South Pole

Dark sector

AMANDA

IceCube

Dome

Skiway

QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.

First Deploymentplanned in

04/05 season.

No more freezing:Deployment will

be in heated environment.

Construction: 11/2004-01/2009

FY04:6FY05:12FY06:16FY07:16FY08:16FY09:14

AMANDA

SPASE-2 South Pole

Dome

Skiway

100 m

Grid North

IceCube

Next season: Buildup of the Drill and IceTop prototypes