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ELECTRONS PROTONS .

THE LARGE HADRON COLLIDER

By Chuck Hobson

G0MDKPress right arrow to advance slide

G0MDK2INTRODUCTION

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!

G0MDK3ELECTRON HISTORY

Joseph John Thomson 1856 - 1940

Thomson's discovered electron in 1897

Awarded Nobel Prize for physics in 1906

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

G0MDK4WHAT IS AN ELECTRON

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

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WHAT IS A PROTON

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)

G0MDK6ENERGY 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

WHAT IS THE ENERGY OF AN ELECTRON?

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POWER AND ENERGY

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

Some Full Licence Amateur Radio revision with a twist

G0MDK8ELECTRON VELOCITY

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.

Can an electron be made to travel at the speed of light ( c )?

Where c = 300,000,000 metres per second

Joule J whereJ1.6x10x1.6x19101TeV 71912

No particle including the electron has ever attained c.

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ELECTRON VELOCITY IN VALVES

Useful chart for determining electron speeds in valves

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ELECTRON VELOCITY IN VALVES

ELECTRON VELOCITY IN A VACUUM TUBE

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ELECTRON VELOCITY IN VALVES

ELECTRON VELOCITY IN A VACUUM TUBE

Formula from A-Level Physics

Calculation

x2x20001.759x10v 11

= 26.5 million metres per second2V

m

ev

o

Let’s increase voltage on Tube Anode and using this formula calc. velocities

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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%)

SOMETHING WENT WRONG! Electrons CANNOT exceed speeded of light (c)

Increase in mass with velocity (relativistic mass) was not taken into account

2Vm

ev

o

G0MDK13ELECTRON VELOCITY 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:

or m x m #1

#3

#2

#4 thus

where

2r v0.5meV

Where eV is a unit of energy used in particle physics

2Vr

m

e vvelocity

Results using the above formulas are shown in next slide

Explanation--

2

mv eV r

2

2

2

cv

1

1

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CORRECTED ELECTRON VELOCITY CHART

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

Note that velocity approaches but doesn’t reach the speed of light (c) However, electron mass starts increasing greatly near c

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PROTON ENERGY VELOCITY CHART

KINETIC ENERGY electron volts

VELOCITY million m/s

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

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LARGE HADRON COLLIDER

CERN Geneva Switzerland Conseil Européen pour la Recherche Nucléaire

European Organization for Nuclear Research

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WHERE IS THE LARGE HADRON COLLIDER

MAP AERIAL VIEW

Cement lined tunnel 3.8m diameter 27km circumference 50m to 170m below the surface.

G0MDK18WHAT’S IT LOOK LIKE

Tech. beside magnet

Inside LHC Tunnel

CMS Detector

(one of four)

G0MDK19WHAT 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

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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

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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

G0MDK22HOW 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

G0MDK23CERN PARTICLE ACCELERATORS

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

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

Y- Lead ions pb +54 54 of 82 –e stripped

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LINEAR ACCELERATORS (How they work)

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

THREE STAGE DC LINEAR ACCELERATOR

FIVE STAGE RF PROTON LINEAR LINEAR ACCELERATOR

G0MDK25PROTON LINEAR ACCELERATOR

Large Hadron Collider (LHC) Linear Accelerator LINAC-2

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

G0MDK26PROTONS IN MAGNETIC FIELDS

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

G0MDK27MAGNETISM

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 MAGNETS1. Permanent (strontium ferrite) ~ 0.1T – 0.2T 2. Resistive (Iron dominant) upper limit ~ 2T saturation3. 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

LHC RELIES ON MAGNETS FOR BEAM FOCUSSING AND BENDING

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SUPERCONDUCTING MAGNETS

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

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

700,000 litres of liquid Helium feeds all cables and magnets

G0MDK29BRIAN 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

G0MDK30PROTON BOOSTER (PSB)

• 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

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)

G0MDK31PROTON 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

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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/colliding-beam-accelerators-%E2%80%94-will-they-reveal-the-ultimate-particles/

G0MDK33LARGE HADRON COLLIDER

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

LHC BEAM PARAMETERS

TeV 0.45 - 7

Circumference 26.7km

Time between collisions

2.5ns

Crossing angle 300 µradians

n/bunch 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)

G0MDK34ATLAS AND CMS DETECTORS

Atlas detector Largest ever made

46m long x 25m high x 25m wide (Half as big as the Notre Dame cathedral)

Weight 7000 tonnes (Weighs same as the Eiffel Tower)

ATLAS CMS

G0MDK35PROTON 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)

G0MDK36EXPERIMENTS

G0MDK37EXPERIMENTAL RESULTS

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!!!

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ANY QUESTIONS?

Thanks for attending

Chuck G0MDK