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Atom Smashers Particle Accelerators and Detectors Mats Selen, UIUC

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fundamental level (Standard Model has. too many free parameters) ... The pursuit of High Energy Physics is motivated by a quest for fundamental understanding. ... – PowerPoint PPT presentation

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Title: Atom Smashers Particle Accelerators and Detectors Mats Selen, UIUC


1
Atom SmashersParticle Accelerators and
DetectorsMats Selen, UIUC
  • Whats the motivation ?
  • How to build a particle accelerator.
  • How to build a particle detector.

A great web site with lots of links
is http//pdg.lbl.gov/particleadventure/english/i
ndex.html
2
Whats the Motivation ?
  • Try to make sense of the way the Universe works
  • Look for simple explanations to complicated
    looking observations !

Complication
Simplification
There is lots of different stuff on earth
3
How to build a Particle Accelerator
First get some particles
4
Now Accelerate Them
Wed like to give them lots of kinetic energy
(lets say 10 GeV)
Do VdG bubble demo
This cant provide enough energy(only a few
million volts) !
Need bigger voltage (and a vacuum system) !!
5
Linear Accelerator
6
Linear Accelerator
7
Linear Accelerator
8
Linear Accelerator
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9
Linear Accelerator
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10
Linear Accelerator
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11
Linear Accelerator
12
Some Examples
LINAC at Bates Lab (MIT)(0.5 GeV)
LINAC at Fermilab(0.4 GeV)
13
A Bigger Example
SLAC (Stanford)(50 GeV)
14
But some people like to recycle...
  • Have the particles go through the same
    accelerator cavitymany times

Circular track(high-vacuum beam-pipe)
This is called aSynchrotron
Key ingredients
Need to make particles go in a circle
Need to keep everything synchronized
15
Forces on Charged Particles
  • Both electric and magnetic fields influence the
    motion of charges.

E/m demoTV demoGeiger demo
F qv x B
16
Synchrotrons
17
Fermilab
Booster (8 GeV)
Main Ring (150 GeV)
Tevatron (1000 GeV)
18
A slick trick Two for the price of one
19
CERN
20
LEP Tunnel
21
How to build a Particle Detector
Ideally, we want to measure everything (E, Px,
Py, Px) about every particleproduced in the
collision.
Charged Particles
Neutral Particles
22
Most Common Approach(for colliding beam
experiments)
Detector package looks like a beer can
23
The Parts
24
How it works
  • All of the parts work more or less the same way
  • Charged particles ionize the material they pass
    through, and we can detect signs of this
    ionization.

1)
Geiger counter
25
How it works
  • All of the parts work more or less the same way
  • Charged particles ionize the material they pass
    through, and we can detect signs of this
    ionization.

2)
detect photon
Scintillator counter
26
Lets Try It
  • We dont have an accelerator handy so lets look
    at cosmic rays

Cloud chamber
27
Scintillation Detector
  • Photons are produced in the plastic by
    scintillating molecules when a cosmic ray muon
    whizzes through it.
  • These photons are detected by a photo-multiplier
    tube, and result in pulses on the oscilloscope.

Singlescoincidencebeta
28
Concluding Remarks
  • The pursuit of High Energy Physics is motivated
    by a quest for fundamental understanding.
  • Current accelerator and detector technology is
    very cool.

29
The Periodic Table
30
The Periodic Table Explained ?
proton
neutron
electron
31
The nucleus is much smaller than the atom
Even so, the nucleus contains gt 99.9 of the
mass of the atom !
32
Energy vs Mass
He (m4.0026 u)
O (M15.9995 u)
So energy is the same as mass somehow ??
Units
33
Mass from Energy
34
Mass from Energy
Ebefore Eafter
35
Units
E mc2
Preferred unit of Energy/Mass GeV
This is a small amount of energy (more
appropriate for chemistry)
1GeV 109 eV (a billion eV)
(about the mass of a protonappropriate scale for
us)
36
It gets more complicated again...
fj
D2
Lc
f2
f3
B
h
Sc
w
D
f4
f2
W
p2
a4
p
f0
K
K3
S
r
a1
h1
a0
Bc
h0
f1
K2
D1
w3
D2
Bs
Ds
K
L
K2
w
D
K1
a2
f
h
K4
B
K3
r3
37
quarks leptons
38
quarks anti-quarks
(baryons)
Now we can easily build any ofof the particles
we have discovered(and predict some we haven't)
(mesons)
39
Example CLEO
40
Example L3
41
Vertex Detector (CLEO)
42
Drift Chamber
43
Calorimeter
44
Solenoid
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