fermilab’sfermilab’s tevatron tevatron && a little bit of...

Fermilab’sFermilab’s TevatronTevatron &&Large Large HadronHadron Collider Collider

(LHC)(LHC)(LHC)(LHC)

Teruki KamonPHYS 736 01PHYS 736-01

1Hadron Collisions at the Tevatron and the LHC

Taken from slides by Ron Moore, Paul Derwent, Mike Syphers (FNAL) (April 2005)Modified/updated by Teruki Kamon for PHYS 627 (TAMU) and PHYS 736 (KNU)

A little bit of Einstein…A little bit of Einstein…R ll th ll k tiRecall the well-known equation:

M i “ l l ” V

2mcE =Measure energy in “electron volts” = eV

(1 eV ≈ 1.6 x 10−19 Joule)

Measure mass in units of eV/c2Measure mass in units of eV/c …

(1 eV/c2 ≈ 1.78 x 10−36 kg)

…but often use units where c ≡ 1,

so mass can also be measured in eV

For a moving particle:

Total Energy = Rest Energy + Kinetic Energy

2222 )()( mcpcmcE γ=+= 211β

γ−

= cv

≡β

22 1 mc)(mcE −+= γ

Hadron Collisions at the Tevatron and the LHC 2

Total Energy Rest Energy Kinetic Energy

Ultra-relativistic: γ >> 1 can neglect rest mass1 mc)(mcE + γ

Fixed Target vs. CollidersFixed Target vs. Colliders/ l l/ l lw/o calculusw/o calculus


Fixed Target vs. CollidersFixed Target vs. Colliders/ l l/ l l

FixedTarget Center of Mass Energy

w/ calculusw/ calculus

Energy E mEs 2=ultrarelativistic limit

Head-On Collision

Energy E Energy E Es 2=

Compare protons @ 1 TeV:Fixed Target: ECM = 43 GeV Collider: ECM = 2000 GeV

Big advantage for colliders! ⇒ Most efficient use of beam energy for physics!Challenge to get a high collision rate to look for interesting (rare) processes


Fixed target still essential for secondary beams: antiprotons, kaons, µ’s, ν’s


TevatronTevatron: : 29 29 Years Later…Years Later…Tevatron discovered topTevatron discovered top, but failed to do much more even though we got 50 times more data since the discovery.Wh ? A tl didWhy? Apparently we did not get high enough in energygy

All the fun stuff must be happening at a bit higher energiesenergies

LHC: next large step

6

CERN Courier (July/August 2009)


intσintσ intσ

A int int

3.46 x 109

crossingscrossingsSkip


LuminosityLuminosityLuminosity is measure of the collision rate in a collider 2

21

4NN

fL =Luminosity is measure of the collision rate in a colliderUnits are cm− 2 s−1

Peak luminosity ~ 1.2 ×1032 cm− 2 s− 1

Goal ~ 4 0 ×1032 cm− 2 s− 1

24πσ

ibibeam each in particles # are

frequency collision is

21 NNf

,

Goal ~ 4.0 ×10 cm s10−24 cm2 = 1 barn; 1032 cm− 2 s− 1 = 360 nb− 1/hr

To reach higher luminosity…M b

size beam is σ

More beam May be hard…Tevatron needs more antiprotons

Higher collision frequency (more bunches)N t f T t ill k i 36 b h f t d ti tNot for Tevatron – will keep using 36 bunches of protons and antiprotons

Smaller beamTevatron beams are ~30 µm wide at interaction pointsLinear colliders have nm size beamsLinear colliders have nm size beams

All can be hard to achieve due to instabilities that may developWant high luminosity to study rare processes

L i i C S i E R


Luminosity × Cross Section = Event Ratee.g., 1 × 1032 cm−2 s− 1 × 10 pb = 3.6 events/hr

Model of AcceleratorModel of AcceleratorAccelerating device + magnetic field to bring it back to accelerateg g gagain

+ =



Where is the Fermilab?Where is the Fermilab?


Looking Down on the Fermilab Accelerator ComplexLooking Down on the Fermilab Accelerator Complex

~5 mi.

CDF

D0


Closely Looking Down on the FermilabClosely Looking Down on the Fermilab

Wilson Hall

Tevatron

1 kmMain Injector


NuMI (120 GeV protons)MiniBoone

(8 GeV)(8 GeV)

21

6

3

57

45

Accelerator Highest Energy

9

Accelerator Highest EnergyCockroft Walton 750 keV

Linac 400 MevBooster 8 GeV

108

Booster 8 GeVMain injector 150 GeVTEVATRON 980 GeV

Machine Energies (Machine Energies (cc = 1)= 1)Comparing relativistic β, γ for electrons and protons at variousenergies…

rest mass

Machine KE β γ β γ

electron511 keV

proton938 MeV

Machine KE β γ β γCockroft-Walton 750 keV 0.926794588 2.47 0.707389304 1.00

FNAL Linac 400 MeV 0.999999186 784 0.818829208 1.43

FNAL Booster 8 GeV 0.999999998 15657 0.994538328 9.53

Main Injector 150 GeV 1 293543 0.999980691 161

ILC 500 GeV 1 978475 0.999998247 534

Tevatron 980 GeV 1 1.918E+06 0.999999543 1046

LHC 7 T V 1 1 761E 07 0 999999995 9596LHC 7 TeV 1 1.761E+07 0.999999995 9596

VLHC? 100 TeV 1 1.957E+08 1 106611

1 keV = 103 eV 1 MeV = 106 eV 1 GeV = 109 eV 1 TeV = 1012 eV


Mass of top quark ≈ 175 GeV

HiHi--rise Buildingrise Building

•25 keV H− ion source


•750 keV Cockcroft-Walton accelerator

CockcroftCockcroft--WaltonWalton

•25 keV H− ion source

750 k V C k ft W lt l t


•750 keV Cockcroft-Walton accelerator

LinacLinac

H− ionsAccelerate H− ions to 400 MeV

116 MeV Alvarez linac (201.25MHz)


400 MeV side-coupled cavity linac (805 MHz)

BoosterBooster

Booster: 8 GeV SynchrotronRuns at 15 Hz

S i f i i j iStripper foil at injection removeselectrons from H− ions

Accelerates protons from 400pMeV to 8 GeV

Most protons (>75%) goingthrough Booster are delivered to


through Booster are delivered toMiniBoone (eventually NuMI)

Main Injector & Recycler RingMain Injector & Recycler Ring

Main InjectorRecycler


Main Injector

Main Injector (MI)Main Injector (MI)R l d M i Ri (f l i T t l)Replaced Main Ring (formerly in Tevaron tunnel)

Higher repetition rate for stacking pbarsSimultaneous stacking and fixed target running

Many operating modesPbar production: ~ 6-7 x 1012 120-GeV protons to pbar target

“Slip-stacking” – merge two booster batches of beam on 1 MI ramp cycleSlip stacking merge two booster batches of beam on 1 MI ramp cycle

“Tevatron protons/pbars”:Accelerate 8 GeV to 150 GeV

9Coalesce 7-9 proton bunches at 90% eff into “270-300 x 109 proton” bunchCoalesce 5-7 pbar bunches at 75-90% eff into “20-80 x 109 antiproton” bunch

Transfer 8-GeV protons/pbars to the RecyclerProvide protons for neutrino production

8-GeV protons for MiniBoone120-GeV protons for NuMI


120-GeV protons for NuMI

120-GeV protons to Switchyard (fixed target area)

Debuncher & AccemulatorDebuncher & Accemulator

Debuncher

Two rings

A lHadron Collisions at the Tevatron and the LHC 23

Accumulator

Pbar (Antiproton) SourcePbar (Antiproton) Source

(1) > 6 x 1012 120-GeV protons per pulse strike Ni target every 2-3 sec; (2) Li lens (740 Tesla/m) collects negative secondaries; (3) Pulsed dipole “PMAG” bends pbars down AP-2 line to Debuncher

ε ≈ (14 18) x 10−6 pbars/proton on target


ε ≈ (14-18) x 10 6 pbars/proton on target

Pbars “debunched”, cooled briefly in Debuncher prior to Accumulator

Pbar (Antiproton) SourcePbar (Antiproton) SourceStack rate = 6-14 mA/hrStack rate 6-14 mA/hr

Depending on stack size; Limited by stochastic cooling systems in Accumulator

Transverse beam size increases linearly with stack size - That’s a drawback…In a really good 24 hour period, nearly 200 x 1010 pbars can be accumulated.

Pbar Production Rate = 3.3 x 10−12 g/day (Mpbar ≈ 1.67 x 10−24 g)

800 million years to make 1 g of antimatter!


Tevatron OverviewTevatron OverviewProton-pbar collisions (Eb = 980 GeV)Proton pbar collisions (Ebeam 980 GeV)Revolution time ~ 21 µsVirtually all of the Tevatron magnets areVirtually all of the Tevatron magnets are superconducting (Cooled by liquid helium, operate at 4 K)

150 GeV beams are injected from MIProtons injected from P1 line at F17; Pbars injected from A1 line at E48

b h f d b i l i b i b36 bunches of proton and pbars circulate in same beam pipe, but separated by “electrostatic separators”3 trains of 12 bunches with 396 ns separation (see the next page)3 trains of 12 bunches with 396 ns separation (see the next page)2 low β (small beam size) intersection points (CDF and D0)8 RF cavities (near F0) to keep beam in bucket acceleration


8 RF cavities (near F0) to keep beam in bucket, acceleration1113 RF buckets (53.1 MHz ⇒ 18.8 ns bucket length)

Proton Bunch PositionsProton Bunch Positions3 i f 12 b h i h 396 i3 trains of 12 bunches with 396 ns separation

P12P12P13

P1P24

P36P25 P36


Protons and Pbars at HEPProtons and Pbars at HEP

Proton bunches

Collide @ CDF

Collide @ D0

P1-P12 A25-A36 A13-A24P13-P24 A1-A12 A25-A36P25-P36 A13-A24 A1-A12

P25~P36


ProtonProton--Pbar Collision PointPbar Collision Point


First Collisions at the TevatronRun 493 Event 11

Run 493 Event 15


24 years ago … 24 years ago …

First Proton-Antiproton Collisions

P il d l ?Pencil and ruler?

We are doing in much better way!Hadron Collisions at the Tevatron and the LHC 31

Large Large HadronHadron ColliderCollider

27 km in Circumference!27 km in Circumference!

One of the largest and the most complex scientific

instrument ever conceived & built by humankind

CMS

pp

LHCbp

ATLAS

ALICE

33

“Largest Science Project Ever”“Largest Science Project Ever”Circular 27 km long tunnelg

50 - 175 meters underground2 beam pipes, 8 sectors

Enormous and very sophisticated magnetic system:magnetic system:

1,232 14.3-m long superconducting dipole magnets keep protons in the orbit

B = 0 5 8 3 T as protons accelerateB = 0.5 – 8.3 T as protons accelerate from 450 GeV to 7 TeV

392 superconducting quadrupole magnets to focus beamsEvery magnet in sync with all others toEvery magnet in sync with all others to keep the beam runningTotal magnetic energy stored is that of Aerobus A380 flying at 700 km/h

Largest “refrigerator” in the world:Largest refrigerator in the world:40,000 tons of cold mass spread over 27 km10,000 tons of Liquid Nitrogen (at T = 80 K)

34

80 K)60 tons of Liquid Helium (cools ring to final 1.9 K)

14 000 x mass of proton (14 TeV) = Collision EnergyProtons fly at 99 999999% of speed of lightProtons fly at 99.999999% of speed of light

2808 = Bunches/Beam100 billion (1011) = Protons/Bunch

7.5 m (25 ns)

7 TeV ProtonProtoncolliding beamsBunch Crossing 40 million (106) Hz

Proton Collisions 1 billion (109) Hz

Parton Collisions

µ+

µ-

Z

e- νe

q

qχ1

-

~q~

Parton Collisions

New Particles 1 Hz to 10 micro (10-5) Hz

p pH

µ+

µ-

Z

Zp p

µ+

µ−

q

q

g~

~

χ20~

χ10~(Higgs, SUSY, ....)

35

One “discovery” event in 10,000,000,000,000Our goal is to find that one event!

Accelerated charges produce radiation.Synchrotron RadiationSynchrotron Radiation

2

retR

)βn(nceE a

&rrr⎥⎦

⎤⎢⎣

⎡ ××=

qvBv =&

Useful equations for ideal conditions in SI

22

3

2222

2

sin444

44

Θvπce)βn(n

πceER

πc

dΩdP

nEπcBE

πcS

a

a

&r&rrr

rrrrr

=××==

=×= mv

γ

2

3

2

32

444

vceP

πcπcπdΩ

&r=

Above we integrated over the angle Θ and below switched to more familiar

pddE r

<<1

224

BUqP ⎞⎜⎛

2

32

2 ⎞⎜⎛=

pdqPr

Above we integrated over the angle Θ, and below switched to more familiar units SI

From here were can get if ττ ddc<<22 BU

mqP⎠⎞

⎜⎝⎛∝γ

326 ⎠⎜⎝ dtcmP επ ο

γ From here were can get if

Go to, for example, Jackson’s Classical Electrodynamics book, find more


, p , y ,convenient expression in terms of v, ρ, γ

fermilab’sfermilab’s tevatron tevatron && a little bit of...

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