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1
Antimatter
1 Antimatter and the Universe
2 Antimatter in the Laboratory
3 Antimatter in Daily Life
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CERN Aerial View
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1 Antimatter and the Universe
Big Bang
13.7 billion years ago
How did the energy transform into mass ?(…and atoms, stars, planets)
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Antimatter
Werner Heisenberg (Nobel prize 1932, on quantum theory)
”I think that this discovery of antimatter was perhaps the biggest jump of all the big jumps in physics in the 20th century.”
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Dirac : Key DiscoveryNobel prize 1933
Paul A. M. Dirac
Relativity + Quantum Theory
‘‘Antiparticles’Antiparticles’
Energy*
* gamma raysantiparticle
particle
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Properties of Antimatter
Every particle has an antiparticleExample: Electron: Mass = 0.511 (MeV) Charge = -1
Positron: Mass = 0.511 (MeV) Charge = +1
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Is the Universe symmetric?1933 Dirac (from his Nobel lecture)
“If we accept the view of complete symmetry between positive and negative electric charge so far as concerns the fundamental laws of Nature, we must regard it rather as an accident that the Earth (and presumably the whole solar system), contains a preponderance of contains a preponderance of negative electrons and positive protons.negative electrons and positive protons.
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It is quite possible that for some of the stars it is the other way about, these stars being built up mainly of positrons and these stars being built up mainly of positrons and negative protons. In fact, there may be half the stars of negative protons. In fact, there may be half the stars of each kind. each kind.
The two kind of stars would both show exactly the same spectra, and there would be no way of distinguishing themno way of distinguishing them by present astronomical methods.”
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We are still searching the answers.
Search for cosmic antimatter
Road No. 1:
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The Search for Antimatter
Anti-Nuclei?
Gamma-rays ?
Solar system?
AMS
NO …
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Clue:
Our Universe is filled with light !
The Antimatter Mystery
Big Bang: 50 % Antimatter
Now: 0 % Antimatter
How did Antimatter disappear?
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Without asymmetry - we would not be here!!
What kind of asymmetry??
Possible Story Line - The “Annihilation Battle”
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Sakharov’s Idea
A.D.Sakharov
Particles decay (a little) faster than antiparticles*
Small imbalance (1,000,000,001:1,000,000,000)Occurs during cool-down of Universe
Most particle-antiparticle pairs annihilate to radiation
Galaxies, stars, planets, us = ‘left-over’
*For experts: this is called ‘CP violation’
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Could matter and antimatter be different?
Fundamental theorem* of physics : “NO” !!
*For experts: the ‘CPT theorem’
Experimental physics : “let’s see … “
Compare properties of
particles with antiparticles
Mass - charge - magnetic momentmagnetic moment - lifetime ?
For example: Compare electrons and positrons
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Precision measurements
rugth30.phys.rug.nl
Electron and Positron are like small magnets.
Their magnetic fields are identical to better than
Many similar tests - no asymmetry found!
But: symmetry violating effects will be very small (if any)
0.000 000 000 1 %0.000 000 000 1 %
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ANTIHYDROGEN - a new precision tool
Best known and simplest (anti) atom
High precision lasers probe energy levels
Comparison: 1 part in 1018 ?
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Anti-Gravity ??
Repeat Galileo’s experiment with (neutral) antihydrogen
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2 Antimatter in the Laboratory
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How to study the Big Bang?
Collision and detection of accelerated particles
Kinetic energy is transformed into new particles
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History of the CERN pbar source•1980-1986 AA
•3.57 GeV/c Antiproton Accumulator ring;
1012
pbars stored (peak). p/pbar collisions in SPS
+ low energy experiments in LEAR
•1986-1996 AAC (AA+AC)•Large acceptance Antiproton Collector ring added.
Production rate increased 10-fold to 6*1010
pbars/h
•1998 - ? AD•AC converted from fixed energy storage ring to
Decelerator. 5*107 pbars slowed down to 100 MeV/c
(5.3MeV kinetic). Local experimental area.
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Antiproton Production today
50,000,000 antiprotons (per 90 s)
Needs (at least) 6.2 GeV of (proton) energy
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Cool Antiprotons …
Antiprotons produced at speed of light
Slow antiprotons down to (almost) rest
Accumulate positrons
Mixing for antihydrogen formation
… Cold Antihydrogen
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Antiproton Decelerator (AD)
Make antiprotons
Slow to 10 % of c
Eject to experiments
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Pbar production
Ir target, cooled 400kA Magnetic Hornfor focussing
•1.5*1013 protons yield 5*107 pbars
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Pbar production
Magnetic fieldsused to filterparticlesw. correctpolarity/energy
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AD cycle
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Stochastic cooling
ALPHA
Slot-line type pickup and kicker
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Electron cooling
30kV 2A electron beam mixed w. pbarsthermal exchange, continuously renewed beam
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View of AD experimental area
ALPHA and ATRAP: study antihydrogen
ASACUSA: study antiprotonic Helium spectrum
ACE: cell irradiation
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Antiproton trapping
QuickTime™ and aAnimation decompressor
are needed to see this picture.
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3 Antimatter in Daily Life
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Antiparticles store energy
Mass is condensed energy
(c2 = exchange rate!)
1 kg = 9 · 101 kg = 9 · 101616 J = 2.5 · 10 J = 2.5 · 101010 kWh = 2.85 GW·year kWh = 2.85 GW·year
(drive VW Polo for 100,000 years without stop)(drive VW Polo for 100,000 years without stop)
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Production ~ 1,000,000,000,000,000 antiprotons/year
Antimatter in large quantities?
Only 0.000 001 milligramme (3 sec on VW Polo) !!
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Antiproton Tumour Therapy?
Antiproton range 0.1 - 15 cm
Annihilation
Local destruction(nuclear fragments)
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First results are encouraging
Antiproton Cell Experiment
(at CERN)
Explores antiproton annihilation in cells
Comparison with protons, heavy ions
Nuclear fragments have short range:
Destroy surrounding tissue (<< 1 mm)
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Summary
Antimatter research helps us understand the origin of our (matter) Universe
Antihydrogen is an important new tool for precision studies (also gravitation!)
Medical applications of antimatter are of great interest
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