UW River Falls, May 15-16, 2003 Searching for Dark Matter Through South Pole Ice Kurt Woschnagg University of California - Berkeley

UW River Falls, May 15-16, 2003

Searching for Dark Matter Through South Pole Ice

Kurt WoschnaggUniversity of California - Berkeley


Outline of Talk

• Introduction• What’s the Matter with Matter?• Are WIMP’s What’s Missing?• WIMP Detection and Neutrinos• Detecting Neutrinos with Ice(Cube

& AMANDA)• Summary


IntroductionEdwin Hubble 1929: The Universe is expanding!

What’s the fate?

Too much Just right Too little

Big CRUNCH Vast EXPANSE


1999: Accelerating Expansion !!



What’s the Matter with Matter?

• It’s Missing!– Let 0 be the energy density of the

Universe

– Evidence Suggest 0=1• Cosmic Microwave Radiation Background

measurements beginning• High Red-shift Type 1a supernovae long ago• Matter observations recent


What’s the Matter with Matter?

Baryonic Matter5%

Dark Matter 35%

Dark Energy60%

Ordinary Matter is less than 0.05 0


Are WIMP’s What’s Missing?

• Relics from the past– Weakly Interacting Massive Particles

• Weak interactions → Survival • Appreciable Mass

• Neutralinos to the rescue– Scatter off nuclei of ordinary matter– Become gravitationally trapped in the

Earth – Neutrinos produced from annihilations


WIMP annihilation

qqllWWZZ,

Higgs…

Earth

Detector


Neutrinos: The Ideal Messengers?

• Neutral– Not affected by magnetic fields

• Weakly interacting– Pass (straight) through intervening

matter– Escape high-density/energy environment

• Abundant– Most prevalent particles


Neutrinos have helped us before:

In our solar system:Neutrinos from the Sun prove internal fusion

Just outside our galaxy:Neutrinos from Supernova 1987A explain last gasp of dying stars

Well beyond our galaxy:Neutrinos from massive Black Holes…some dayNeed to look at higher energies → larger detectors!

However…


““I have done a terrible I have done a terrible thing, I have invented a thing, I have invented a particle that cannot be particle that cannot be

detected.”detected.”Wolfgang PauliWolfgang Pauli

Only weak interactions → indirect detection


How to build a neutrino detector

• Look for the neutrino’s interaction product (e,,)

• Use the earth as a filter

• Needle in haystack: 1 in 1,000,000 is

Earth

Detector

cosmic ray


Cherenkov radiation: sonic boom of light

How to detect muons from neutrinos


• Need something transparent• Need large volume of it• Can’t pay a lot for it• Need electricity, food, transportation, etc

• Antarctic ice is the purest, most transparent natural medium on earth• South Pole ice cap is two miles thick• South Pole ice is “free”• US has permanent base at South Pole

Build it at the South Pole!


AMANDAAntarctic Muon and Neutrino Detector

Array

– 677 light sensors– 200 m diameter, 600m high – Buried under 1400 m of ice

Popular ScienceApril, 2001, p. 70Hunting the Invisible

~4 neutrinos per day



Holes are drilledwith hot water

2000 m deep60 cm wide3-4 days



Antarctic geography

South PoleAmundsen-Scott station (US)

McMurdo station

Lake Vostok

New Zealand & US

Greenwich (UK)





Amundsen-Scott South Pole station

South PoleDome

Skiway

Summer camp

IceCube

AMANDA

“North”

Dark sector


UW River Falls, May 15-16, 2003The

Dome

The new station


Summer camp


The AMANDA counting house:MAPO (Martin A. Pomerantz Observatory)


WIMPs seen so far: 0

• Just started looking• Need more time to catch one, or

• Need bigger detector →

IceCube – 1 km3 of ice


IceCubeIceCube1400 m

2400 m

AMANDA

South Pole

Skiway

80 Strings 4800 sensors 1 km3 volume (1Gt) First string to be

deployed in Dec 2004 To be completed in

2010 AMANDA contained

within IceCube~300 neutrinos per day

SurfaceIceTop

UW River Falls, May 15-16, 2003IceTop tank


11 US and 10 European institutions and 1 Japanese university11 US and 10 European institutions and 1 Japanese university (most of them are also AMANDA member institutions)(most of them are also AMANDA member institutions)

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. Dept. of Physics, University of Maryland, USA13. University of Mons-Hainaut, Mons, Belgium14. Dept. of Physics and Astronomy, University of Pennsylvania, Philadelphia, USA15. Dept. of Astronomy, Dept. of Physics, SSEC, PSL, University of Wisconsin, Madison, USA16. Physics Department, University of Wisconsin, River Falls, USA17. Division of High Energy Physics, Uppsala University, Uppsala, Sweden18. Fysikum, Stockholm University, Stockholm, Sweden19. University of Alabama, Tusceloosa, USA20. Vrije Universiteit Brussel, Brussel, Belgium21. Chiba University, Japan22. Imperial College London, UK

The IceCube CollaborationThe IceCube Collaboration


Summary

• Only 5% of matter is ordinary matter• WIMPs are missing-matter candidates• Neutrinos can be used to detect WIMPs• Neutrinos are detected indirectly• AMANDA (and soon IceCube) looks for

WIMPs trapped in the center of the Earth and the Sun

Documents

UW River Falls, May 15-16, 2003 Searching for Dark Matter Through South Pole Ice Kurt Woschnagg University of California - Berkeley