Antimatter
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Antimatter and the Universe
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Antimatter in the Laboratory
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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
”I think that this discovery of antimatter
was perhaps the biggest jump of all the
big jumps in physics in the 20th century.”
Werner Heisenberg
(Nobel prize 1932, on quantum theory)
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Dirac : Key Discovery
Nobel prize 1933
Relativity + Quantum Theory
Paul A. M. Dirac

‘Antiparticles’
particle
Energy*
* gamma rays
antiparticle
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Properties of Antimatter
Every particle has an antiparticle
Example:
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 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 negative
protons. In fact, there may be half the stars of each kind.
The two kind of stars would both show exactly the same spectra, and there would
be no way of distinguishing them by present astronomical methods.”
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We are still searching the answers.
Road No. 1:
Search for cosmic antimatter
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The Search for Antimatter
Solar system?
Anti-Nuclei?
Gamma-rays ?
AMS
NO …
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The Antimatter Mystery
Big Bang:
Now:
50 % Antimatter
0 % Antimatter
How did Antimatter disappear?
Clue:
Our Universe is filled with light !
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Possible Story Line - The “Annihilation Battle”
Without asymmetry - we would not be here!!
What kind of asymmetry??
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Sakharov’s Idea
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
A.D.Sakharov
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 moment - lifetime ?
For example: Compare electrons and positrons
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Precision measurements
Electron and Positron are like small magnets.
rugth30.phys.rug.nl
Their magnetic fields are identical to better than
0.000 000 000 1 %
Many similar tests - no asymmetry found!
But: symmetry violating effects will be very small (if any)
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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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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;
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pbars stored (peak). p/pbar collisions in SPS
+ low energy experiments in LEAR
•1986-1996
AAC (AA+AC)
•Large acceptance Antiproton Collector ring added.
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Production rate increased 10-fold to 6*10
pbars/h
•1998 - ? AD
•AC converted from fixed energy storage ring to
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Decelerator. 5*10 pbars slowed down to 100 MeV/c
(5.3MeV kinetic). Local experimental area.
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Antiproton Production today
Needs (at least) 6.2 GeV of (proton) energy
50,000,000 antiprotons (per 90 s)
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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
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•1.5*10
400kA Magnetic Horn
for focussing
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protons yield 5*10 pbars
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Pbar production
Magnetic fields
used to filter
particles
w. correct
polarity/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. pbars
thermal 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 a
Animation decompressor
are needed to see this picture.
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Antimatter in Daily Life
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Antiparticles store energy
Mass is condensed energy
(c2 = exchange rate!)
1 kg = 9 · 1016 J = 2.5 · 1010 kWh = 2.85 GW·year
(drive VW Polo for 100,000 years without stop)
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Antimatter in large quantities?
Production ~ 1,000,000,000,000,000 antiprotons/year
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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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)
First results are encouraging
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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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