Transcript G0MDK - FRARS

G0MDK
1
ELECTRONS
PROTONS
.
THE LARGE HADRON COLLIDER
By
Chuck Hobson
G0MDK
Press right arrow to advance slide
INTRODUCTION
G0MDK
2
This presentation is primarily on the Large Hadron collider.
It starts out with a short lecture on electrons and protons
because understanding their properties and behaviour will
be helpful in appreciating what the Large Hadron Collider is,
what it does, and how it works.
I hope you will find it informative and enjoyable.
Now on with the show!
ELECTRON HISTORY
G0MDK
3
Thomson's discovered electron in 1897
Awarded Nobel Prize for physics in 1906
Joseph John Thomson
1856 - 1940
Three experiments which led Thompson to receiving the
Nobel Prize were:
1. demonstrating magnetic deflection of cathode rays
2. demonstrating electrostatic deflection of cathode rays
3. measuring electron charge to mass ratio
WHAT IS AN ELECTRON
G0MDK
4
IT IS A TINY CHARGED PARTICLE FOUND IN ALL MATTER
HERE ARE SOME OF ITS PROPERTIES
•
Radius < 10-15 metres
•
Rest mass 9.1 × 10-28 grams
•
Charge neg. 1.6 × 10-19 Coulombs
HOW SMALL? ~ thousand trillion electrons side by side measure 2m
HOW HEAVY? 1.2 thousand trillion trillion electrons weigh one gram
HOW POTENT? 6.25 million trillion electrons make a 1 Coulomb charge
One Coulomb flowing per second = one Ampere where
one Coulomb is made up of 6.25 x 1018 electrons
One gram of electrons contains
176,000,000 Coulombs of charge
WHAT IS A PROTON
G0MDK
5
IT IS ALSO TINY CHARGED PARTICLE FOUND IN ALL MATTER
COMPARING THE PROTON TO AN ELECTRON:
• The proton is found in the nucleus of all atoms
• The electron is found rotating about the nucleus of all atoms
• Proton charge is Pos. 1.6 × 10-19 Coulombs
• Proton has a mass of 2.9 x 10-25 grams
• This is 1836 times heavier than the electron (9.1 x 10-28 grams)
• The proton can be regarded as a hydrogen ion.
NOTE: The proton (hydrogen ion) along with other ion candidates such as
lead 207pb82 are being used in high energy particle experiments at the
Large Hadron Collider.
Lead ion Pb51+ (51 of 82 electrons stripped from lead atom)
ENERGY OF AN ELECTRON
G0MDK
6
WHAT IS THE ENERGY OF AN ELECTRON?
An electron must be moving to have kinetic energy
It acquires such motion when placed in an electric field
Electric field points from pos. to neg.
Electron accelerates towards pos. electrode
Electron acquires max. energy at pos. electrode
Electron energy reaches 1000 electron volts (1000eV) at pos. electrode
The “electron volt” (eV) concept will be discussed later
POWER AND ENERGY
G0MDK
7
Some Full Licence Amateur Radio revision with a twist
1. Q = charge (Coulomb is unit of charge)
2. I = Ampere (unit is of current) I is the rate of charge flow Q/s
3. W = Watt (unit of power. It is the rate of energy flow J/s
4. J = Joule (unit of energy) J= QV
5. Another unit of energy is the electron volt eV
6. J = eV (a convenient unit used in high energy particle Physics)
7. The charge Q of an electron is a tiny (1.6 × 10-19 Coulombs)
8. So: one eV = 1V x 1.6 × 10-19 = 1.6 × 10-19 J
ELECTRON VELOCITY
G0MDK
8
Can an electron be made to travel at the speed of light ( c )?
Where c = 300,000,000 metres per second
No, but almost.
Reason:
1.
An electron is a particle with mass as previously shown.
2.
As the electron approaches c its mass increases enormously.
3.
This is in accordance with Einstein’s “Special Relativity”.
4.
This has been demonstrated at CERN, SLAC and elsewhere.
5.
Particle accelerators have attained over TeV energy levels.
6.
1TeV = One Trillion electron Volts of energy.
1TeV  1012 x1.6x19 19  1.6x10 7 J where J  Joule
No particle including the electron has ever attained c.
ELECTRON VELOCITY IN VALVES
G0MDK
9
Useful chart for determining electron speeds in valves
ELECTRON VELOCITY IN VALVES
ELECTRON VELOCITY IN A VACUUM TUBE
G0MDK
10
ELECTRON VELOCITY IN VALVES
G0MDK
11
ELECTRON VELOCITY IN A VACUUM TUBE
Formula from
A-Level Physics
e
v
2V
m
o
Calculation
v  1.759x1011 x2x2000
= 26.5 million metres per second
Let’s increase voltage on Tube Anode and using this formula calc. velocities
G0MDK
12
ELECTRON VELOCITY CHART
Anode voltage
(kilovolts)
Electron Velocity
million metres/s
Velocity to
speed of light ratio
8.00
53.
0.177 (12.5%)
16.00
75
0.250 (25%)
64.00
150
0.500 (50%)
128.0
212
0.701 (70%)
256.0
300
1.000 (100%)
512.0
424*
1.410 (141%)
v
e
2V
m
o
SOMETHING WENT WRONG! Electrons CANNOT exceed speeded of light (c)
Increase in mass with velocity (relativistic mass) was not taken into account
ELECTRON VELOCITY EXPLANATION
G0MDK
13
Explanation-As an electron velocity approaches c (speed of light) its mass increases
This is in accordance with Einstein’s theory “Special Relativity”
That is to say: relativistic mass (mr) = gamma (  ) times mo
Relativistic mass calculations are done using the following formulas:
#1
#3
mr   x mo
velocity v 
#4 thus
where
e
2V
m
r
v 2 mr
eV 
2
#2

1
v2
1 2
c
eV  0.5mr v 2
Where eV is a unit of energy
used in particle physics
Results using the above formulas are shown in next slide
CORRECTED ELECTRON VELOCITY CHART
G0MDK
14
Note that velocity approaches but doesn’t reach the speed of light (c)
However, electron mass starts increasing greatly near c
KINETIC ENERGY
electron volts
VELOCITY
million m/s
GAMMA
mass increase
400eV
4.5
1.00011
35keV
106.4 ( ~ 1/3 c) 1.0692
79keV
149.5 ( ~ 1/2 c) 1.1534
103keV
169.8
1.2132
207keV
213.9
1.4264
661keV
270.0
2.2942
2.2MeV
294.54
5.2644
4.36MeV
298.35
9.5288
9.8MeV
299.64
20.1898
65.4MeV
299.9907
128.932
PROTON ENERGY VELOCITY CHART
KINETIC ENERGY
electron volts
VELOCITY
million m/s
G0MDK
15
GAMMA
mass increase
750keV
4.5
1.00011
66MeV
106.4 ( ~ 1/3 c) 1.0692
145.1MeV
149.5 ( ~ 1/2 c) 1.1534
200MeV
169.8
1.2132
400MeV
213.9
1.4264
1.214GeV
270.0
2.2942
4GeV
294.54
5.2644
8GeV
298.35
9.5288
18GeV
299.64
20.1898
120GeV
299.9907
128.932
800GeV
299.99979
853.878
1000GeV (1TeV)
299.99988
1067.1
7000GeV (7TeV)
299.999990
7500
NOTE
299,999,990m/s
is just 10m/s short
of the speed of
light
G0MDK
16
LARGE HADRON
COLLIDER
CERN Geneva Switzerland
Conseil Européen pour la Recherche Nucléaire
European Organization for Nuclear Research
G0MDK
17
WHERE IS THE LARGE HADRON COLLIDER
MAP
AERIAL VIEW
Cement lined tunnel 3.8m diameter 27km circumference
50m to 170m below the surface.
WHAT’S IT LOOK LIKE
G0MDK
18
Inside LHC Tunnel
CMS Detector
(one of four)
Tech. beside magnet
G0MDK
19
WHAT IS THE LARGE HADRON COLLIDER?
A huge synchrotron in a subterranean concrete lined tunnel ~ 100m deep
The synchrotron has two evacuated tubes running in opposite directions
Protons are accelerated to near light speeds in these tubes and collided
Four extremely complicated detectors are located along the tubes
They are placed at four designated collision points
The detectors are named: ATLAS, ALICE, CMS and LHCb
Collision by-products are studied in the quest for new particles
Why bother when expenditures to date (4/20/10) are ~ 10 billion Euros?
The following 2.5 minute video offers some answers
WHAT DOES THE LHC DO?
Click on URL below (light grey) to see video
When video is finished ~2.5 minutes,
RETURN TO SLIDE SHOW BY:
1. Clicking on LEFT pointing arrow upper left web page corner
2. Continue slide show using key-board RIGHT arrow
URL
http://www.youtube.com/watch?v=bNNZtpDYZBU
G0MDK
20
G0MDK
21
HOW DOES THE LHC WORK?
CERN is a massive complex of scientific equipment.
It is made up of:
1.
The LHC, a 27km circumference synchrotron
2.
Three smaller synchrotrons
3.
A linear accelerator
4.
A proton generator
5.
Four huge detectors
The way this all works is described in the following video
HOW DOES THE LHC WORK?
Click on URL below (light grey) to see next video
When video is finished ~10 minutes,
RETURN TO SLIDE SHOW BY:
1. Clicking on LEFT pointing arrow upper left web page corner
2. Continue slide show using key-board RIGHT arrow
http://www.youtube.com/watch?v=TIeY7Zj27IM
G0MDK
22
CERN PARTICLE ACCELERATORS
G0MDK
23
1. Electrons stripped from hydrogen and
injected into Linear accelerator
2. Linear accel. Accelerates protons to 100
million m/s (proton energy 50MeV)
3. Booster accel. Protons to 275 million m/s
(proton energy 800MeV)
4. Proton synchrotron increases speed to
99.9% c giving proton 25GeV energy and
increases rest mass x 25
5. SPS increases proton energy to 450GeV
and rest mass x 450
Y- Lead ions pb +54
54 of 82 –e stripped
6. LHC increases proton energy to 7TeV and
rest mass x 7000 There are 2 beams of
protons counter rotating for 2 hours before
entering the collision area
LINEAR ACCELERATORS
(How they work)
G0MDK
24
THREE STAGE DC LINEAR ACCELERATOR
Proton enter on the left
Protons shown in accelerating gap Note rf polarities
rf polarities change as protons enter drift tubes
Protons accelerated five times Note “disk spacing”
Higher energy protons exit on right
FIVE STAGE RF PROTON LINEAR LINEAR ACCELERATOR
PROTON LINEAR ACCELERATOR
Large Hadron Collider (LHC)
Accelerator LINAC-2
G0MDK
25
Linear
2007 Ran 5044 hrs. 98.7% up time!
INPUT: Proton (hydrogen ions 350mA)
OUTPUT:
Pulsed protons 20µs–150µs 1s rate
50MeV protons (185mA) at 1/3c
Quadrupole magnet beam focusing
PROTONS IN MAGNETIC FIELDS
G0MDK
26
PROTONS ENTERS BOTTOM
DRIFTING AT CONSTANT SPEED
MAGNETIC FIELD CAUSES PROTONS
TO BEND RIGHT ANGLE TO MAGNET
LINES OF FORCE
PROTON SPEED REMAINS CONSTANT
BECAUSE MAGNETIC FIELD DOES
NOT ADD OR SUBTRACT ENERGY
FROM THE PROTONS
SECTION OF SYNCHROTRON
MAGNETIC STRENGTH ADJUSTED TO KEEP PROTONS ON TRACK
MAGNETISM
G0MDK
27
LHC RELIES ON MAGNETS FOR BEAM FOCUSSING AND BENDING
The SI unit of magnetic field flux density is the Tesla [T]
T units very large µT and nT usually more practical
Another unit in common usage is the gauss [G] , (CGS)
1T = 10,000G
THREE TYPES OF MAGNETS
1. Permanent (strontium ferrite) ~ 0.1T – 0.2T
2. Resistive (Iron dominant) upper limit ~ 2T saturation
3. Super-conducting ~ 10T
Large Hadron Collider ring (~ 27km circumference)
Uses 1232 dual 56mm aperture 14.2m long SC Magnets (8.4T)
Called arc magnets. Bends proton beam around the circle
Magnet increases 0.54T to 8.4T as proton energy increases .45TeV – 7TeV
SUPERCONDUCTING MAGNETS
G0MDK
28
Magnet and blue cooling unit being
assembled (One of 1232 magnets)
Assembled length 14.2m
Weight > 20 tonnes
Strength 0.54T to 8.4T
Bending for 0.51 – 7.0TeV protons
700,000 litres of liquid
Helium feeds all cables and
magnets
13,000A at maximum strength
Cooled to –269.1 C 1.9 kelvin
Niobium-titanium alloy wire
~200 tonnes of NbTi cable in the
LHC and kept at 1.9k
G0MDK
29
BRIAN COX ON WHAT WENT WRONG
The 3rd and last Video for this slide show.
Click on URL below (light grey) to see last video
When video is finished ~2.5 minutes,
RETURN TO SLIDE SHOW BY:
1. Clicking on LEFT pointing arrow upper left web page corner
2. Continue slide show using key-board RIGHT arrow
http://www.youtube.com/watch?v=YnAVjkuQz-Y
PROTON BOOSTER (PSB)
G0MDK
30
Four rings stacked 36cm sep
Each ring has its own RF
accelerator cavity
32 four beam bending magnets
48 quadrupole beam focussing
magnets
(magnets not shown in figure)
•
Entering Protons begin speeding around taking 1.67µs per turn
•
The Protons are given synchronized kicks every turn by the RF cavity
•
After many rotations protons reach 275m/s taking 0.64µs per turn
•
RF freq. increased as protons speedup maintaining beam sync.
•
Proton ring outputs recombined 4 x 2 bunches of protons at 1.4GeV
PROTON SYNCHROTRON (PS)
628m circumference Proton Synchrotron built in late 1950’s
Input 1.4GeV protons from 4 ring Proton Booster
Output 25GeV protons to Super Proton Synchrotron
G0MDK
31
G0MDK
32
SUPER PROTON SYNCHROTRON (SPS)
7km circumference ring buried ~20m
744 dipole magnets for steering and 216 quadropole mag
http://blog.modernmechanix.com/2008/10/05/collidingbeam-accelerators-%E2%80%94-will-they-reveal-theultimate-particles/
LARGE HADRON COLLIDER
LHC BEAM PARAMETERS
TeV
0.45 - 7
Circumference
26.7km
Time between
collisions
2.5ns
Crossing angle
n/bunch
300 µradians
11 x 1010
n bunches
2808
Beam radius
16µm
Filling time
7.5 min.
Accelerations
1200
Proton mass
X 7,500 @ 7TeV
Beam revolutions
11000/s (90µs)
G0MDK
33
In tunnel 50m – 170m deep
Two 60mm beam tubes to carry
protons in opposite directions
Beam tubes filled twice a day
1232 super conducting beam
bending magnets
386 super conducting beam
focussing magnets
Many small correcting magnets
for beam corrections
400MHz RF cavities for proton
beam accelerators
All of above bathed in liquid
helium keeping Temp. at -269.30 C
ATLAS AND CMS DETECTORS
G0MDK
34
Atlas detector Largest ever made
46m long x 25m high x 25m wide
(Half as big as the Notre Dame cathedral)
Weight 7000 tonnes
ATLAS
(Weighs same as the Eiffel Tower)
CMS
PROTON COLLISIONS AT ATLAS
2800 bunches of protons are going around LHC at 7TeV near c
Bunches spaced 7m each being 80mm long and 16µm diameter
100 billion protons per bunch ~ 20 collisions occur
2800 bunches making 11,000 turns/s = 31 million crossings
Thus 600 million protons collide each second.
One petabyte of raw data per second is collected.
One petabyte = 1000 terabytes (1000 trillion bytes ~ X 8 gives bits)
G0MDK
35
EXPERIMENTS
G0MDK
36
EXPERIMENTAL RESULTS
G0MDK
37
FOUR LARGE DETECTORS: ATLAS – CMS – ALICE - LHCb
•
Located around the 27km ring at particle collision points
•
Very busy places
•
They identifies particles measure their momentum and energy
•
Atlas collects 1 peta-byte (1000 trillion bytes) of data per second
•
This is enough data to fill 1.5 million double layer DVDs
•
Worldwide LHC Computing Grid (WLCG) a vast computing network
•
Combines computing resources of 100,000 processors at 170 cites
•
Provides near real time access to scientists in 34 countries.
•
Data to US is via fibre optics from CERN
•
Data from the (28-03-2010) 7TeV collisions being analysed now
•
It will take years to do the analyses
•
J. J. Thompson really started something, didn’t he!!!
G0MDK
38
ANY QUESTIONS?
Thanks for attending
Chuck G0MDK