# Presentation: 041596

## First Results from IceCube

**First Results from IceCube**

- Physics Motivation
- Hardware Overview
- Deployment
- First Results
- Conclusions & Future Plans

- Spencer Klein, LBNL
- for the IceCube Collaboration

- See Paolo Desiati’s AMANDA talk

## The IceCube Collaboration

**USA (12)**

**Europe (12)**

**Japan**

- New Zealand

-  Alabama University, USA
-  Bartol Research Institute, Delaware, USA
-  Pennsylvania State University, USA
-  UC Berkeley, USA
-  UC Irvine, USA
-  Clark-Atlanta University, USA
-  Univ. of Maryland, USA

-  IAS, Princeton, USA
-  University of Wisconsin-Madison, USA
-  University of Wisconsin-River Falls, USA
-  LBNL, Berkeley, USA
-  University of Kansas, USA
-  Southern University and A&M College, Baton Rouge, USA

-  Universite Libre de Bruxelles, Belgium
-  Vrije Universiteit Brussel, Belgium
-  Université de Mons-Hainaut, Belgium
-  Universiteit Gent, Belgium
-  Humboldt Universität, Germany
-  Universität Mainz, Germany
-  DESY Zeuthen, Germany
-  Universität Dortmund, Germany

-  Universität Wuppertal, Germany
-  Kalmar university, Sweden,
-  Uppsala university, Sweden
-  Stockholm university, Sweden
-  Imperial College, London, UK
-  Oxford university, UK
-  Utrecht university, Netherlands

-  Chiba university, Japan
-  University of Canterbury, Christchurch, NZ

**ANTARCTICA**

***The IceCube Collaboration***

## Physics Motivation

- Search for cosmic-ray accelerators
- Protons are bent in galactic magnetic fields
-  are produced by hadron accelerators
- HE (>5*1013 eV) photons are absorbed by interaction with 30K microwave background photons
-  --> e+e-
- Study the High-Energy Universe
- ~100 GeV – 1019 eV
- Cross section & effective area rise with energy, so a single detector can cover a very wide energy range

## Physics Topics

- Source searches
- Active Galactic Nuclei
- Supernova remnants
- Gamma-Ray Bursts
- Calculations predict 1-10 /km3/year from many source models
- Neutrino physics
- Expect 100,000 atmospheric /year
- Cross-section measurements
- Absorption in earth
- Decoherence
- Oscillations
- Searches for supersymmetry, WIMPs, MeV  from supernovae, monopoles, Q-balls....

-         Crab Nebula

- Active Galactic Nucleus

## Detector Requirements

- Need 1 km3 area for a good chance to see signals
- Requires a natural material
- Ice or water
- South Pole Ice has
- Long absorption length
- Shorter scattering length
- Depth dependent
-  Low dark noise rates

- Ice model:
- Scattering vs. wavelength and depth

## Lessons from AMANDA

- AMANDA pioneered astronomy at the South pole
- Deployed first OMs 1993/4
- Observed atmospheric 
- Deep ice (> 1 km) has good optical qualities
- Data transmission to surface nontrivial
- Paolo Desiati’s talk will present AMANDA results

- A muon in
- AMANDA

## 1 gigaton instrumented volume
80 strings of 60  digital optical modules
1450-2450 m deep
17 m spacing
125 m hexagonal grid
Each DOM is an autonomous data collection unit
IceTop air shower array
160 surface water tanks
Each contains 2 DOMs

- 80 strings of 60  digital optical modules
- 1450-2450 m deep
- 17 m spacing
- 125 m hexagonal grid
- Each DOM is an autonomous data collection unit
- IceTop air shower array
- 160 surface water tanks
- Each contains 2 DOMs

**IceCube**

**1 string + 8 tanks deployed Jan. 2005**

## , e and 

- IceCube will distinguish , e and based on the event characteristics
-  -->  produce long muon tracks
- Good angular resolution, limited energy resolution
- Atmospheric  are a significant background to searches for extra-terrestrial 
- Soft energy spectra --> may improve signal to noise ratio by optimizing for higher energy 
- e --> e produce EM showers
- Good energy resolution, poor angular resolution
- Above ~1016 eVproduce ‘double-bang’ events
- One shower when the  is created, another when it decays

## Simulated  Events

- Eμ=6 PeV, 1000 hits

- Eμ=10 TeV, 90 hits

- Simulated  Events

## A simulated multi-Pev  event

- as a single shower
- n.b. c=300 m for
- E = 6 TeV

- A simulated multi-Pev  event

## Digital Optical Module

*main board*

*LED flasher board*

*PMT base*

*25 cm PMT*

*33 cm Benthosphere*

- Hardware

## Analog Front-End

- Want to measure arrival time of every photon
- 2 waveform digitizer systems
- 200-700 Megasamples/s, 10-bit
- switched capacitor array
- 3 parallel digitizers give 14 bits of dynamic range
- 128 samples --> 400 nsec range
- Dual chips to minimize dead-time
- 40 Megasamples/s, 10-bit ADC
- 256 samples --> 6.4 s range
- Self-triggered
- Also, ‘local-coincidence’ circuitry looks for hits in nearby modules

- An ATWD waveform

- Time bin (3.3 ns)

## DOM Readout

- Each DOM is a ‘mini-satellite’
- FGPA + ARM7 CPU for                              control, data compression...
- Packetized data is sent to surface
- Baseline data transmission
- waveforms for local coincidence data
- Rate ~ 15-30 Hz
- timing and charge info for isolated hits
- Rate ~ 700 Hz
- ‘Rapcal’ timing calibration maintains                clock calibration to  < 2 nsec

- A ‘Main Board’

## Surface DAQ

- Trigger based on multiplicity & topology (in a sliding time window)
- Selected data saved to tape
- High-priority data sent north over a satellite link
- GPS clock for overall timing

**Amundsen-Scott South Pole station**

- South Pole

- Dome (old station)

- “Summer camp”

- road to work

- IceCube

- Skiway

- http://icecube.wisc.edu

**AMANDA**

## The drilling site in January, 2005

*The drilling site in January, 2005*
*Hot-water drilling*

*Hose reel*

*IceTop tanks*

- The 5 MW water heater
- for the hot water drill
- (car-wash technology)

- Hose Reel

## An IceTop tank  

*Each 2 m dia. IceTop tank contains two DOMs.  *

**An IceTop tank***  *

-  signals from IceTop DOMs

## Schedule & Logistics

**Schedule & Logistics**

- Can work  December --> mid-February
- Logistics are a huge concern
- Freight, power, ... are expensive!
- Weather is always a factor

-  The new South-Pole station

## 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 **_**20:40**_**: First communication to DOM**

## 2 high-multiplicity muon events

- Time Residual (ns)

- Time Residual (ns)

- Time Residual (ns)

- Depth (m)

- Depth (m)

## First Results from String 21

- Time calibration
- Muon reconstruction
- Timing verification with muons
- Timing and Energy measurement  with LED flashers
- Coincidence events
- IceCube - IceTop

## Time Calibration

**Time Calibration**

- Time

-   IceTop

-    In-ice DOMs

-    IceTop

## Muon and Flasher Reconstruction

- Observe Cherenkov radiation from charged particle tracks
- Muons produce ~ km long tracks
- + hadronic shower at interaction point
- EM cascades produce ~ point sources
- LED flashers are a surrogate for e
- Reconstruct both with maximum likelihood techniques
- Use arrival times of all photons, as determined from waveform information

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

## Muon zenith angle distribution

**Muon zenith angle distribution**

## Timing studies with muons

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

- Residual Timing (ns)

- Scattering  (1/m)

## A flasher event

**A flasher event**

- Equivalent to ~ 60 TeV e

- Flasher

- Color --> arrival time    Circle size --> Amplitude

## Timing resolution from flashers

- 1.74 ns rms

- {

- Photon arrival time difference between DOM45 & 46

## Energy Measurement for flashers

- Reconstruct energy of flash for each flashing DOM, using known position
- Variation due to
- Ice models
- LED intensity
- Detector Response..
- Good agreement across entire string

- All LEDs
- Side LEDs
- 450 LEDs
- ~1/3 Intensity

## IceTop and in-ice coincidences

**IceTop and in-ice coincidences**

- Some of the difference is due to shower curvature

## Conclusions & Outlook

- IceCube will explore the high-energy  sky.
- With a 1 km3 effective area, IceCube has the power to observe extra-terrestrial neutrinos.
- We deployed our first string in January, 2005.
- 76 out of 76 DOMs are working well.
- Timing resolution is < 2 nsec
- Next austral summer, we will deploy 8-12 more strings.
- Largest neutrino observatory in the world.
- By 2010, we will have instrumented ~ 1 km3.

## Extras/Backup

- IceCube reviewers – read no farther

## 10” PMT

**10” PMT**
**Hamatsu-7****0**

## Muon Angular Resolution

**Waveform**
**information**
**not used.**
**Will ****improve**
**resolution** **for**
**high energies**** !**

## Timing verification with light-flashers

**Timing verification with ****light-flashers**