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G0MDK 1 ELECTRONS PROTONS. THE LARGE HADRON COLLIDER By Chuck Hobson G0MDK Press right arrow to advance slide.

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Presentation on theme: "G0MDK 1 ELECTRONS PROTONS. THE LARGE HADRON COLLIDER By Chuck Hobson G0MDK Press right arrow to advance slide."— Presentation transcript:

1 G0MDK 1 ELECTRONS PROTONS. THE LARGE HADRON COLLIDER By Chuck Hobson G0MDK Press right arrow to advance slide

2 G0MDK 2 INTRODUCTION 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!

3 G0MDK 3 ELECTRON HISTORY Joseph John Thomson 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

4 G0MDK 4 WHAT IS AN ELECTRON IT IS A TINY CHARGED PARTICLE FOUND IN ALL MATTER HERE ARE SOME OF ITS PROPERTIES Radius < metres Rest mass 9.1 × grams Charge neg. 1.6 × 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 electrons One gram of electrons contains 176,000,000 Coulombs of charge

5 G0MDK 5 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 × Coulombs Proton has a mass of 2.9 x grams This is 1836 times heavier than the electron (9.1 x grams) The proton can be regarded as a hydrogen ion. NOTE: The proton (hydrogen ion) along with other ion candidates such as lead 207 pb 82 are being used in high energy particle experiments at the Large Hadron Collider. Lead ion Pb51+ (51 of 82 electrons stripped from lead atom)

6 G0MDK 6 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 WHAT IS THE ENERGY OF AN ELECTRON?

7 G0MDK 7 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 × Coulombs) 8.So: one eV = 1V x 1.6 × = 1.6 × J Some Full Licence Amateur Radio revision with a twist

8 G0MDK 8 ELECTRON 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 No particle including the electron has ever attained c.

9 G0MDK 9 ELECTRON VELOCITY IN VALVES Useful chart for determining electron speeds in valves

10 G0MDK 10 ELECTRON VELOCITY IN VALVES ELECTRON VELOCITY IN A VACUUM TUBE

11 G0MDK 11 ELECTRON VELOCITY IN VALVES ELECTRON VELOCITY IN A VACUUM TUBE Formula from A-Level Physics Calculation = 26.5 million metres per second Let’s increase voltage on Tube Anode and using this formula calc. velocities

12 G0MDK 12 ELECTRON VELOCITY CHART Anode voltage (kilovolts) Electron Velocity million metres/s Velocity to speed of light ratio (12.5%) (25%) (50%) (70%) (100%) *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

13 G0MDK 13 ELECTRON 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 (m r ) = gamma ( ) times m o Relativistic mass calculations are done using the following formulas: #1 #3 #2 #4 thus where Where eV is a unit of energy used in particle physics Results using the above formulas are shown in next slide Explanation--

14 G0MDK 14 CORRECTED ELECTRON VELOCITY CHART KINETIC ENERGY electron volts VELOCITY million m/s GAMMA mass increase 400eV keV106.4 ( ~ 1/3 c) keV149.5 ( ~ 1/2 c) keV keV keV MeV MeV MeV MeV Note that velocity approaches but doesn’t reach the speed of light (c) However, electron mass starts increasing greatly near c

15 G0MDK 15 PROTON ENERGY VELOCITY CHART KINETIC ENERGY electron volts VELOCITY million m/s GAMMA mass increase 750keV MeV106.4 ( ~ 1/3 c) MeV149.5 ( ~ 1/2 c) MeV MeV GeV GeV GeV GeV GeV GeV GeV (1TeV) GeV (7TeV) NOTE 299,999,990m/s is just 10m/s short of the speed of light

16 G0MDK 16 LARGE HADRON COLLIDER CERN Geneva Switzerland Conseil Européen pour la Recherche Nucléaire European Organization for Nuclear Research

17 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.

18 G0MDK 18 WHAT’S IT LOOK LIKE Tech. beside magnet Inside LHC Tunnel CMS Detector (one of four)

19 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

20 G0MDK 20 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

21 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

22 G0MDK 22 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

23 G0MDK 23 CERN 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 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 of 82 –e stripped

24 G0MDK 24 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

25 G0MDK 25 PROTON LINEAR ACCELERATOR Large Hadron Collider (LHC) Linear Accelerator LINAC 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

26 G0MDK 26 PROTONS 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

27 G0MDK 27 MAGNETISM 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 LHC RELIES ON MAGNETS FOR BEAM FOCUSSING AND BENDING

28 G0MDK 28 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

29 G0MDK 29 BRIAN COX ON WHAT WENT WRONG The 3 rd 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

30 G0MDK 30 PROTON 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)

31 G0MDK 31 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

32 G0MDK 32 SUPER PROTON SYNCHROTRON (SPS) 7km circumference ring buried ~20m 744 dipole magnets for steering and 216 quadropole mag beam-accelerators-%E2%80%94-will-they-reveal-the- ultimate-particles/

33 G0MDK 33 LARGE 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 C LHC BEAM PARAMETERS TeV Circumference26.7km Time between collisions 2.5ns Crossing angle300 µradians n/bunch11 x n bunches2808 Beam radius16µm Filling time7.5 min. Accelerations1200 Proton massX 7TeV Beam revolutions11000/s (90µs)

34 G0MDK 34 ATLAS 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

35 G0MDK 35 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)

36 G0MDK 36 EXPERIMENTS

37 G0MDK 37 EXPERIMENTAL 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 ( ) 7TeV collisions being analysed now It will take years to do the analyses J. J. Thompson really started something, didn’t he!!!

38 G0MDK 38 ANY QUESTIONS? Thanks for attending Chuck G0MDK


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