Facts and Myths of the LHC, and the consequences for Astronomy

By: Stephen Demjanenko

Outline

•(Really) Quick History of Particle Physics•LHC

▫Design▫Detectors▫Goals▫Test Run

•Applications of Astrophysics

Quick History of Particle physics• Began with the study of the atom and has

now progressed to subatomic▫Protons, neutrons, electrons, antimatter as

well as constituents (quarks)• As of the 1970’s particle theory was

condensed into the Standard Model▫Predicts 252 unique particles

• Since then work has been done to go beyond the Standard Model▫The LHC hopes to test this as well as complete

the Standard Model with the discovery of the Higgs

First Particle Accelerator•John D. Cockcroft and

Ernest Walton▫Cavendish Laboratory

•In 1930 they managed to accelerate protons across a potential of 800 kilovolts

•1932 – they split a lithium nucleus into alpha particles

Major Particle Accelerators

•Brookhaven National Laboratory – Relativist Heavy Ion Collider ▫Gold and other ions, polarized protons

•Fermilab – Tevatron (proton-antiproton)•Stanford - SLAC (electron-positron)•*CERN – LHC (proton-proton)•Cornell Electron Storage Ring

▫Not major but its here at Cornell▫40 ft below practice football/track fields

LHC Overview•Built by the

European Organization for Nuclear Research (CERN)

•10,000 scientists collaborated

•Cost ~ $8 billion•Generates 1 GBps of

data

What it is not

•A weapon•Earth’s Doomsday•blackhole/

wormholecreator

Myths

•Recently Walter L. Wagner and Luis Sancho sued CERN over the use of the LHC claiming it would destroy the planet▫Did the same thing for

FERMILAB•The case was thrown

out

Black Hole Myth

•The LHC does have the ability to create a black hole

•However, by Hawking radiation, all black holes are evaporating▫Slow for large black holes but for any black

hole the LHC could create it would evaporate in about 10-17 s

•Once again, the LHC is SAFE

Cosmic Rays• Cosmic rays are

continually hitting the atmosphere

high energy extragalactic particles

▫Have energies similar/greater than the LHC can achieve Nothing bad has

happened yet The Earth is still here

• LHCf experiment

So what is it?

•The LHC is the most powerful particle collider ever built▫Took 14 years of planning/construction

•It will collide two proton beams at 14 TeV (7 TeV each beam)▫Also can collider lead ions (2.74 TeV)

Where is it?

•Located 100m underground

•Is in Switzerland and France

•Located in the old LEP collider tunnel▫Reused existing tunnel

with a few modifications▫3.7m in width, 27km in

circumference

Design•1,232 dipole magnets, 392 quadrupole

magnets▫Maintains circular path and focuses the

beam respectively▫Weigh about 27 tons each▫Twin bore design used to reduce space

Also magnetically couples the two beams•700,000 liters of liquid helium are used

for cooling (1.9K)•Base energy is 450 GeV and a couple

times a day they are accelerated to 7 TeV

Beam Injection

Detectors

•Could see up to 600 million collisions per second

•6 different detectors for different types of collisions▫LHCf

ATLAS

•General purpose detector•Higgs particle•extra dimensions (could

explain weakness of gravity)?•Dark matter?•44m long, 25m in diameter•Weighs 7,000 tons•Most complex detector ever

built

CMS•Also a general purpose

detector•Works with ATLAS to

detect the Higgs•Also looks for dark

matter (WIMPs)▫Weakly interacting

massive particles Also known as cold

dark matter

ALICE•Studies quark-gluon

plasma that existed shortly after the big bang

•LHC is 100,000 hotter than center of sun▫Might be hot enough to

free quarks from within protons

•Will observe how the plasma cools and creates subatomic matter

LHCb

•Will try to explain the asymmetry between matter and anti-matter▫There is much more

matter than antimatter•Will study the bottom

quark

TOTEM

•440m long, 5m wide, 5m high•20 tons•Will be located inside the CMS detector•Size of proton•Beam luminosity

Goals

•Understand the early universe better▫Ion collider will be particularly useful for

this•Find experiments to test the validity of

Grand Unified Theories, and possibly string theory

•Detect the predicted Higgs Boson▫Expected to exist at energies this machine

can reach

Standard Model

•Is the current accepted model of particle physics

•Explains the interactions between strong, weak and electromagnetic forces

•Does not include gravity•Every predicted particle has been

detected except for the Higgs Boson

Higgs Boson•Principle of Inertia

▫A body in motion will continue in the same motion given there is no applied force

•Where does mass come from?

•Theory suggests that inertia comes from the interaction of a body with some resistive field

Higgs (cont.)

•The Higgs boson makes up this field

•LHC may produce a Higgs every hour▫Would take 3 years to

acquire enough data Requires many events

in order to statistically confirm its existence

Test Run

•The LHC started up on September 10th at 4:27am sending a stream of protons around at 451 GeV

•There were no collisions – only one beam circulated

•On September 19th the LHC was shutdown for repairs

•Is expected to resume operations in spring 2009

Problems with Test Run

•After 2 days of operation a transformer for the liquid helium failed and part of the tunnel warmed up▫Wasn’t reported for a week▫Took a week to cool that section back from

4.4 K to 2.1 K

Problems (cont.)•A faulty electrical

connection between two magnets caused a helium leak▫Caused the collider to

be taken offline for the remainder of the year

•24 quadrupole and 8 dipole magnets were damaged

LHC@Home

•There is a distributed computing client which has been working about a year

•Works to simulate protons circulating in the LHC▫Helps to develop a control sequence to

maintain proton containment Could cut into the magnets, taking the

accelerator offline

Applications to Astronomy•Clearly the LHC is not a telescope• It does not make observations of the cosmos• It does allow us to experiment with incredibly

high energies, energies seen only in the first few seconds following the big bang

•Allows us to check validity of theories▫We use these theories to model the evolution of

the universe▫Also helps us describe high energy astrophysics

Applications (cont.)• As mentioned

earlier the Higgs Boson is predicted to carry mass

• By better understanding gravity we can figure out why gravity is much weaker than any of the three other forces