# Presentation: 181181

## Design and Performance of the IceCube Electronics

- R. G. Stokstad
- (Lawrence Berkeley National Laboratory)
- for the IceCube Collaboration

*High Energy Neutrino Astronomy*
*IceCube Detector*
*DAQ and Electronics*
*Performance*
*Summary and Outlook*

*Heidelberg, September 12, 2005*

## Discover the origin of H.E. Cosmic Rays
C.R. with energies up to 1020 eV are observed.
Where are they accelerated?
Candidate sources:
SNe remnants, Quasars
Active Galactic Nuclei
Gamma Ray Bursts
Exotics (decays of topological defects...)

- C.R. with energies up to 1020 eV are observed.
- Where are they accelerated?
**Candidate sources:**
- SNe remnants, Quasars
- Active Galactic Nuclei
- Gamma Ray Bursts
- Exotics (decays of topological defects...)

**Guaranteed sources (from Cosmic Rays):**
** **Atmosphere
-        C.R. induced   & K decay)
-  galactic plane:
-      C.R. interacting with ISM
** **Cosmos
-        C.R. interacting with CMB
-                UHE  p  +  n + (p 0)

- Goals of High Energy Neutrino Astronomy

**•****Searches** for exotica:
-       Wimps,
-       Monopoles,
-       ...

*MAP THE NEUTRINO SKY*

## H.E. Neutrino Detection

*~ *km-long muon tracks
-     from 

- Longer absorption length => larger effective volume

- Event reconstruction by Cherenkov light timing

- ~10m-long cascades,
- e   neutral current

*Large volume, shielding => deep water/ice*

## Detectors for High Energy Neutrino Astronomy

- AMANDA
- ANTARES
- BAIKAL
- ICECUBE
- NEMO
- NESTOR

*Cf. Session A1 Tuesday, 11:00 on NEMO electronics.*

*An active and growing field including operating detectors, construction, and planned projects.*

- KM3Net

## Site of AMANDA and IceCube:

**South Pole**

**Station**
**facilities**

**AMANDA**

**road to work**

- 1500 m

- 2000 m

- [not to scale]

**IceCube**

- Amundsen-Scott South Pole Station

## IceCube

- 70-80 Strings
- 4200-4800 PMTs
- Instrumented volume: ~1 km3  (1 Gton)
- IceCube will detect neutrinos of all flavors at energies from 1011 eV to 1020 eV, and low energy ’s from supernovae

- IceTop
- Air shower array

- String 21

## The drilling site in January, 2005

*The drilling site in January, 2005*

*Hose reel*

*IceTop tanks*

## Each 2 m dia. IceTop tank contains two Digital Optical Modules.  The freezing of the water is done in a controlled manner to produce clear ice. 

*Each 2 m dia. IceTop tank contains two Digital Optical Modules.  The freezing of the water is done in a controlled manner to produce clear ice. *

## 	IceCube’s First String: January 28, 2005

_**27.1**__**, 10:08**_**: **Reached maximum depth of 2517 m
_**28.1**__**, 7:00**_**: **preparations for string installation start
_**9:15**_**: **Started installation of the first DOM
_**22:36**_**: **last DOM installed
*12 min/DOM*
_**22:48**_**: **Start drop
_**29.1**__**, 1:31**_**: **
- String secured
- at depth of
**2450.80 m**
_**20:40**_**: **First
- communication
- to DOM

- 	IceCube’s First String: January 28, 2005

## Ice Drives the Design

- Surface temperatures     -20oC 70oC
- At-depth temperatures    -35oC 10oC
- Freeze-in subjects cables, connectors, optical modules to high stress
- Inaccessibility requires reliability, remote operation
- 	----
- Once modules are deployed, have stable environment
- No radioactivity in ice   PMT rate < 1kHz
- Optical scattering relaxes timing requirements
- Prototype string (41 Digital Optical Modules) deployed in Jan. 2000 (AMANDA -”String-18”)

## Quality data, maximum information, high information/noise (identify, analyze rare events) 
Timing (ability to reconstruct tracks, locate vertices)
       <7ns rms    
Waveform capture (all photons carry information)
       300 MHz  (for 400 ns), 40 MHz (for 6.4 sec)
Charge dynamic range (energy resolution)
       >200PE/15ns 
Onboard calibration devices 
      LEDs for int. & ext. calibration.  Electronic pulser 
Hardware local coincidence in the ice
      Nearest and next-nearest neighbor
Communications signaling rate to surface  
      1 Mbaud/twisted pair

- Timing (ability to reconstruct tracks, locate vertices)
-        <7ns rms
- Waveform capture (all photons carry information)
-        300 MHz  (for 400 ns), 40 MHz (for 6.4 sec)
- Charge dynamic range (energy resolution)
-        >200PE/15ns
- Onboard calibration devices
-       LEDs for int. & ext. calibration.  Electronic pulser
- Hardware local coincidence in the ice
-       Nearest and next-nearest neighbor
- Communications signaling rate to surface
-       1 Mbaud/twisted pair

- ‘Electronic’ Requirements

*3 ns*

*~500 PE/15 ns*

## ‘Environmental’ Requirements

- Robust equipment for a harsh environment
-        copper cable, rugged connectors
- Effective operation (reduce manpower at S. Pole)
-  automatic, self-calibration; remote commissioning
- Low power (fuel expensive at S. Pole)
-  ≤ 5 W/DOM
- Insensitivity to interference from other experiments at S. Pole:  VLF, Radar
- 	   Common mode rejection
- Long life time  > 10 years after completion
-   Design for reliability
- Minimize cost
-   Two DOMs per twisted pair

## IceCube DAQ Block Diagram

## The DAQ is based on the Digital Optical Module, a semi-autonomous sensor/processor with high functionality.

## DOM MB Block diagram

- FPGA

- CPU

- CPLD

- Flash

- Flash

- PMT Power

- SDRAM

- SDRAM

- ATWD

- ATWD

- Monitor
- & Control

- LPF

- LC

- x16

- x2

- x0.25

- Flasher
- Board

- Pulser

- DACs & ADCs

- Corning Frequency Ctl (was Toyocom)

- 4Mb    4Mb

- 16Mb
- 16Mb

**+/**-5V, 3.3V,  2.5V, 1.8V

- 64 Bytes

- Trigger (2)

- Oscillator

- 20 MHz

- 40 MHz

- MUX

- (n+1)

- (n–1)

- DOR

**OB-LED**

- x 2.6

- x 9

- 10b

- 10b

- 10b

- 10b

- 8b

- 32b

- 16b

- 8b

- 8b, 10b, 12b

- 1 megabaud

- DC-DC

- Configuration
- Device

- 8Mbit

- Delay

## Key Components

- Analog Transient Waveform Digitizer - ATWD
- Custom ASIC having high speed and low power consumption
- Switched capacitor array
- 4 channels  x  128 samples deep, acquisition on launch
- Digitization: 10 bit,  30 s /channel
- Variable sampling speed:  250 - 800 MHz
- Power consumption 125 mW
- Design - S. Kleinfelder ~1996 (also used in KamLAND, NESTOR)

- 2 ATWD/DOM:  0.25 W

## DOM MB Block diagram

- FPGA

- CPU

- CPLD

- Flash

- Flash

- PMT Power

- SDRAM

- SDRAM

- ATWD

- ATWD

- Monitor
- & Control

- LPF

- LC

- x16

- x2

- x0.25

- Flasher
- Board

- Pulser

- DACs & ADCs

- Corning Frequency Ctl (was Toyocom)

- 4Mb    4Mb

- 16Mb
- 16Mb

**+/**-5V, 3.3V,  2.5V, 1.8V

- 64 Bytes

- Trigger (2)

- Oscillator

- 20 MHz

- 40 MHz

- MUX

- (n+1)

- (n–1)

- DOR

**OB-LED**

- x 2.6

- x 9

- 10b

- 10b

- 10b

- 10b

- 8b

- 32b

- 16b

- 8b

- 8b, 10b, 12b

- 1 megabaud

- DC-DC

- Configuration
- Device

- 8Mbit

- Delay

## Key Components, cont.

- Very stable crystal oscillator
- Provides time stamp for launch of ATWD
- Clock for FPGA, CPU, FADC, DACs, ADCs
- Allan Variance         typical ~1 x 10-11
- Toyocom                 16.6 MHz     $ 7 used in AMANDA prototype
- Vektron/Corning      20 MHz      $70  chosen for reliability, specs
-                                                            10-10,  -40oC,  tested

## DOM MB Block diagram

- FPGA

- CPU

- CPLD

- Flash

- Flash

- PMT Power

- SDRAM

- SDRAM

- ATWD

- ATWD

- Monitor
- & Control

- LPF

- LC

- x16

- x2

- x0.25

- Flasher
- Board

- Pulser

- DACs & ADCs

- Corning Frequency Ctl (was Toyocom)

- 4Mb    4Mb

- 16Mb
- 16Mb

**+/**-5V, 3.3V,  2.5V, 1.8V

- 64 Bytes

- Trigger (2)

- Oscillator

- 20 MHz

- 40 MHz

- MUX

- (n+1)

- (n–1)

- DOR

**OB-LED**

- x 2.6

- x 9

- 10b

- 10b

- 10b

- 10b

- 8b

- 32b

- 16b

- 8b

- 8b, 10b, 12b

- 1 megabaud

- DC-DC

- Configuration
- Device

- 8Mbit

- Delay

## Key Components, cont.

- FPGA + CPU
- Altera EPXA 4
- System On a Programmable Chip
- FPGA
- 400,000 gates
- 20, 40 MHz
- CPU
- ARM922T  32-bit processor
- Single Port SRAM  128 Kbytes
- Dual Port SRAM  64 Kbytes
- 80 MHz
- Power consumption 0.5 - 0.7 W

- Supports:  control, communications, ATWD readout, data compression, calibration, .....

## Digital Optical Module Mainboard

- Mainboard design, fabrication and testing by Lawrence Berkeley National Laboratory

## Digital Optical Module

**D**igital **O**ptical **M**odule

- 4W

## Digital Optical Module

- DOM assembly facilities at U.Wisconsin, DESY-Zeuthen, U. Stockholm

## Key Components, cont.

- The ~ 3km Cable
- 0.9 mm copper wire
- Twisted quad configuration
- 145 Ohm impedance     DC resistance  < 140 Ohm/2.5km (cold)
- low cross talk between twisted pairs is essential
- > 50 db  suppression near end cross talk
- > 30 db  suppression far end cross talk
- Requires careful mechanical construction.

- 45 mm

- Two twisted pair per quad

## Surface Front-End Readout Card (“DOR” card)

- Readout Card design, fabrication, testing by DESY-Zeuthen

## DOR (Digital Optical module Readout)

- DOR (**D**igital **O**ptical module **R**eadout)
- Surface front-end readout card

- 0.7 W/DOM

## DOM Hubservices 1 String = 60 DOMs

- DOM Hubservices 1 String = 60 DOMs

- 8 DOR Cards

- GPS
- distr.

- Chassis Fans

- Power Distr. Card

- DOM Power Supplies

- CPU

- ~300 W running 60 DOMs

- Hard Drive

## RELIABILITY 

- Goals  and constraints
- 10 years operation after construction
- <0.2%/yr complete failure,  <1%/yr partial failure
- Inaccessibility of components after deployment
- Cost vs component quality (comm., indust., mil.)
- Use sound reliability & design practice
- Parts selection
- Derating
- Preferred, qualified vendors
- Special attention to key components
- Quality fabrication (IPC 610 class 3 - used for medical, satellite applications)
- Testing, Testing, and more Testing

## Some reliability design consequences 

- Used industrial parts spec’d to -40oC
- Tin-lead solder used wherever possible
- Electrolytic caps replaced with higher reliability plastic caps
- High stability crystal oscillator (~$7 Toyocom replaced by ~$70 Corning)
- Found and replaced component types that did not operate properly at low temperature.

## Testing Sequence

- Mainboard Design Verification Testing
- Small number of boards tested
- Software test suite resident on Mainboard
- Extreme conditions - determine range of operation
- -80oC to +80oC,  30 G rms vibration
- Mainboard Production Testing
- All boards tested
- Temperature cycling (+65oC to -50oC), vibration 7 G rms
- Burn in 24 hours at +65oC    24 hours at -50oC
- Integration testing with other DOM components
- 3 km cable
- PMT
- Flasher board

## Testing Sequence, cont.

- Final Acceptance Testing of assembled DOMs
- 14 days at temperatures down to -55o C
- Communications
- Calibration
- Timing with laser, fiber optic distribution
- Retest all DOMs before deployment
- Ambient temperature -25oC to -35oC

- Transport to South Pole

## Performance

- Time calibration
-  Detector verification with LED flashers
-  Muon reconstruction
-  Timing verification with muons
-  Coincidence events
- IceCube - IceTop
- IceCube - AMANDA

## Time Calibration

- Time

## Timing verification with flashers

- {

## Timing verification with flashers

## Some typical high-multiplicity muon events

## Time calibration verification using muons

- The random and systematic time offsets from one DOM to the next are small,
- ≤ +/- 3ns

## IceCube muon data reconstruction

## IceTop and in-ice coincidences

- The difference is due to shower curvature

## AMANDA and in-ice coincidences

- Off-line search through GPS time-stamped AMANDA and IceCube string- 21 events.

## Summary

-  The first IceCube string and four IceTop stations have been sucessfully deployed
-  All 76 DOMs function well
- The overall detector timing uncertainty was measured to be <3 ns
-  Muons and air showers have been analyzed
-  The observed muon flux is consistent with the expectation from simulations
- The first components of the IceCube detector perform as expected, or better.

- OUTLOOK
- 2005-06  up to       10 strings
-                                (IceCube >AMANDA)
- 2006-07            14-16
- 2007-08            16-18
- 2008-09	      16-18
- 2009-10  	      _14-18_
- 	                         71-79 strings

## THE ICECUBE COLLABORATION

**USA: **
** ****Bartol Research Institute, Delaware**
** ****Univ. of Alabama**
** ****Pennsylvania State University**
** ****UC Berkeley**
** ****UC Irvine**
** ****Clark-Atlanta University**
** ****Univ. of Maryland**
** ****IAS, Princeton**
** ****University of Wisconsin-Madison**
** ****University of Wisconsin-River Falls**
** ****Lawrence Berkeley National Lab.**
** ****University of Kansas **
** ****Southern University and A&M **
**	****  ****College, Baton Rouge**

**Sweden:**
** ****Uppsala Universitet**
** ****Stockholm Universitet**

- (The IceCube Collaboration now includes AMANDA)

**UK:**
** ****Imperial College, London**
** ****Oxford University**

**Netherlands:**
** ****Utrecht University**

**Belgium:**
** ****Université Libre de Bruxelles**
** ****Vrije Universiteit Brussel**
** ****Universiteit Gent**
** ****Université de Mons-Hainaut**

**Germany:**
** ****Universität Mainz**
** ****DESY-Zeuthen**
** ****Universität Dortmund**
** ****Universität Wuppertal**
** ****Universität Berlin**

**Japan:**
** ****Chiba university**

**New Zealand:**
** ****University of Canterbury**

## Slide 44

## <footer>

- <date/time>

## Optical Scattering in S.P. Ice

## Time calibration verification using muons

- •  reconstruct muon tracks without DOM X
- •  plot the time residual for DOM X for nearby reconstructed tracks
- •  if optical scattering length is longer than the distance cut (10 m) the most likely residual should
-     be 0, otherwise residual will show delay increasing with the amount of scattering.

- Time residual = (photon arrival time - reconstructed time*)
- *assuming no scattering.

## Inside the DOM Hub

- For GPS distribution

## Slide 49