Abigail Bickley, Dept of Chemistry, July 25, 2008 Large Hadron Collider

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Abigail Bickley, Dept of Chemistry, July 25, 2008

Large Hadron Collider

July 25, 2008 Abigail Bickley, PAN 2008 2

Where is the LHC?


Where is the LHC?Switzerland

France

Circumference: 27km = 16.8miles


Where is the LHC?


Deconstructing a Name• Collider:

– Two beams of particles circulate in opposite directions around the ring

– Beams intersect at 4 locations

– These locations are where the collisions occur and are observed by warehouse sized detectors

• Hadron• Large




Deconstructing a Name• Collider • Hadron:

– General category for the type of particles accelerated (protons and heavy nuclei)– Hadrons (from the Greek ‘adros’ meaning ‘bulky’) are particles composed of quarks.

The protons and neutrons that atomic nuclei are made of belong to this family. On the other hand, leptons are particles that are not made of quarks. Electrons and muons are examples of leptons (from the Greek ‘leptos’ meaning ‘thin’).

• Large

10-10 m

u u

d

10-15 m10-9 m


Deconstructing a Name• Large:

– The size of an accelerator is related to the maximum beam energy obtainable.– This is a function of the radius of the machine and the strength of the dipole

magnetic field that keeps particles in their orbits. – The LHC re-uses the 27‑km circumference tunnel that was built for the previous

big accelerator, LEP. – The size of the tunnel, magnets, cavities and other essential elements of the

machine, represent themain constraints that determine the design energy of 7 TeV per proton beam.


Colliders vs Cyclotrons• Cyclotrons:

– Produces a single beam of ions that are directed towards a stationary target

– Maximum beam energy is dependent upon the radius of the cyclotron

• Colliders:– When two beams collide, the energy of

the collision is the sum of the energies of the two beams.

– A beam of the same energy that hits a fixed target would produce a collision of much less energy.



€

ECollision ∝ Ebeam

€

ECollision = Ebeam1 + Ebeam2


Recipe for Creating an Ion Beam



1 Ion Source:– All protons accelerated at CERN are obtained from standard hydrogen.– Protons are isolated by stripping orbiting electrons off of hydrogen atoms.– Although proton beams at the LHC are very intense, only 2 nanograms of

hydrogen are accelerated each day. – It would take the LHC about 1 million years to accelerate 1 gram of

hydrogen.



2 Multi-Stage Acceleration:– The accelerator complex is a succession of machines with

increasingly higher energies. – Each machine injects the beam into the next one, which brings the

beam to an even higher energy.



0.050 GeV

1.4 GeV

25 GeV

450 GeV

7000 GeV



3 LHC = Final Acceleration– Protons at full energy in the LHC will be traveling at

0.999999991 times the speed of light. – Each proton will go round the 27 km ring more than 11,000 times

a second.– Entire acceleration process takes ~30min







4 Collision Tuning:– Beam is produced in “bunches” not a continuous stream of particles.– A filled ring contains 2808 bunches.– Each bunch contains 1.1x1011 protons– Arrival of bunches from both beams at the interaction region must be

timed perfectly to create collisions– 600M collisions per second


Power Consumption

• Annual operation requires 800,000 MWh• Equivalent to the entire state of Geneva• Machine only operates 270 days/year• Cooling of the superconducting magnets consumes the

majority of the power (9593 total magnets)• Electricity is provided by France

– 20% of French electricity is generated in nuclear power plants


CERN Price Tag

Annual energy cost: $30M

Construction Costs

Personnel Materials Total

Facility $890M $3550M $4,440M

Injector $87M $67M $154M

Computing $87M $87M $174M

Total $1,064M $3,704M $4,768M


Existing Colliders/AcceleratorsFacility Location Max

EnergySpecies Science

LHC France & Switzerland

7 TeV

2.76 TeV/u

Proton

Lead

Higgs, Super Symmetry, etc

RHIC Brookhaven, NY 200 GeV Proton, Gold Quark Gluon Plasma

Tevatron Batavia, Il 1 TeV (Anti)-Proton Top quark

CEBAF Newport News, VA 4 GeV

(12 GeV)

Electrons Nucleon sub-structure

RHIC from space


Why Collide Nuclei?


Evolution of the Universe

LHC equivalent to t = 10-25seconds.As time progressed the universe expanded and cooled.

Free quarks and gluons became confined.


The Particle Zoo• The nucleus of an atom is

composed of protons & neutrons

• But these particles also have a quark substructure– Proton = uud– Neutron = udd

• The antimatter equivalent to the proton is the antiproton (uud)

Proton


The Particle ZooQuark Charge Mass

Up +2/3 1.9 MeV

Down -1/3 4.4 MeV

Strange -1/3 87 MeV

Charm +2/3 1.32 GeV

Bottom (Beauty)

-1/3 4.24 GeV

Top

(Truth)

+2/3 172.7 GeV


Scientific Goals of LHC: Higgs Boson

• The Higgs boson is a hypothesised particle which, if it exists, would give the mechanism by which particles acquire mass.

• Referred to in the lay press as the “God particle”• Higgs proposed that the whole of space is permeated by a field, similar

in some ways to the electromagnetic field. • As particles move through space they travel through this field, and if

they interact with it they acquire what appears to be mass. • This is similar to the action of viscous forces felt by particles moving

through any thick liquid. the larger the interaction of the particles with the field, the more mass they appear to have.

• Force carrier of the Higgs field is the Higgs boson.

‘Well, either we've found the Higgs boson, or Fred's just put the kettle on’

http://www.oufusion.org.uk/newssummer01/fusionnewssummer01.htm


Scientific Goals of LHC• What is dark matter?

– Observations of visible matter accounts for only 4% of the Universe.

– The search is open for particles or phenomena responsible for dark matter (23%) and dark energy (73%).

– A very popular idea is that dark matter is made of neutral but still undiscovered supersymmetric particles.– The gravitational effect of dark matter may make galaxies spin faster than expected– The gravitational field of dark matter deviates the light of objects behind it.


Common Misconceptions

– Theoretical existence– Created in high energy collisions of particles such as the protons– Public concern is that the energy of the collisions at the LHC will be sufficient

to create microscopic black holes

• Scientific Rebuttal:– Cosmic rays are particles produced in outer space that are accelerated to

energies far exceeding those of the LHC. – Cosmic rays travel throughout the Universe, and have been bombarding the

Earth’s atmosphere continually since its formation 4.5 billion years ago. – Since the much higher-energy collisions provided by nature for billions of years

have not harmed the Earth, there is no reason to think that any phenomenon produced by the LHC will do so.

Massive Black Hole

• Public concern exists about the possibility of black hole creation at LHC

• Macroscopic Black Holes:– Massive black holes are formed in nature as a

result of star collapse– Results in a very large amount of matter being

confined to a very small volume

• Microscopic Black Holes:


Watching a Collision• Microscopic view

0 fm/c ~2 fm/c ~7 fm/c >7fm/c

Time ~6x10-24s ~21x10-24s >21x10-24s

Remember: E=mc2 so lots of energy means lots of mass!!!


Watching a Collision


The Detectors: CMS• Compact Muon

Solenoid

• Cylindrical detector– 69ft long– 52ft diameter– 25,000,000lbs

• Cost:– $480M

• Collaboration:– ~2600 people– 180 institutions– 38 countries

Scientific Goal:general‑purpose detector designed to cover the widestpossible range of physics, from the search for the Higgsboson to supersymmetry (SUSY) and extra dimensions


The Detectors: CMS• Compact Muon

Solenoid


• Cost:– $480M

• Collaboration:– ~2600 people– 180 institutions– 38 countries

Scientific Goal:general‑purpose detector designed to cover the widestpossible range of physics, from the search for the Higgsboson to supersymmetry (SUSY) and extra dimensions


The Detectors: ATLAS • No acronym

• Dimensions– 151ft long– 82ft diameter– 7,000,000lbs

• Cost:– $520M

• Collaboration:– 1900 people

– 164 institutions

– 35 countriesScientific Goal:general‑purpose detector designed to cover the widestpossible range of physics, from the search for the Higgsboson to supersymmetry (SUSY) and extra dimensions


The Detectors: ATLAS • No acronym

• Dimensions– 151ft long– 82ft diameter– 7,000,000lbs

• Cost:– $520M

• Collaboration:– 1900 people

– 164 institutions

– 35 countriesScientific Goal:general‑purpose detector designed to cover the widestpossible range of physics, from the search for the Higgsboson to supersymmetry (SUSY) and extra dimensions


The Detectors: ALICE• A Large Ion Collider

Experiment


• Cost:– $110M

• Collaboration:– 1500 people – 104 institutions– 31 countries

Scientific Goal:specialized in analysing lead-ion collisions. It will study the properties of quark-gluon plasma, a state of matter where quarks and gluons, under conditions of very high temperaturesand densities, are no longer confined inside hadrons. Such astate of matter probably existed just after the Big Bang, before Particles such as protons and neutrons were formed.



Experiment


• Cost:– $110M





Experiment


• Cost:– $110M



ALICE Virtual Tour

http://petermccready.com/portfolio/07041606.html


The Detectors: LHCb

Scientific Goal:specializes in the study of the slight asymmetry between matterand antimatter present in interactions of B-particles (particlescontaining the b quark). Understanding it should prove invaluablein answering the question: “Why is our Universe made of the matterwe observe?”

• Large Hadron Collider beauty

• Dimensions

– 69ft long

– 33ft high

– 43ft wide

– 5,600,000lbs

• Cost:

– $520M



The Detectors: LHCb

Scientific Goal:specializes in the study of the slight asymmetry between matterand antimatter present in interactions of B-particles (particlescontaining the b quark). Understanding it should prove invaluablein answering the question: “Why is our Universe made of the matterwe observe?”

• Large Hadron Collider beauty

• Dimensions

– 69ft long

– 33ft high

– 43ft wide

– 5,600,000lbs

• Cost:

– $520M



Data Rates and Volume• Raw Rate:

– 150M sensors record data at 40M/s

• Filtered Rate:– 100 collisions per sec

• Annual Data:– 15PB = 15,000,000GB– 100,000 DVDs per year



3miles

9.3miles

18.6miles12.4miles




The Grid

• Data access required for all collaborators• Geographically dispersed globally• The creation of a "virtual supercomputer" composed of a network of

loosely-coupled computers, acting in concert to perform very large tasks.

July 25, 2008 Abigail Bickley, PAN 2008 36http://www.symmetrymagazine.org/breaking/2008/04/14/what-can-we-expect-from-the-lhc/

Countdown….• June 16th, 2008: beam pipe completed• August 2008: beam injection into LHC• October 2008: beam circulation• December: first collisions???!!!


Stay Tuned….


Resources• LHC Homepage

– http://lhc.web.cern.ch/lhc/

• LHC Status & Schedule– http://www.lhcountdown.com/

• US LHC– http://www.uslhc.us/LHC_Science

• LHC Safety– http://public.web.cern.ch/Public/en/LHC/Safety-en.html

• CERN Web– http://public.web.cern.ch/Public/en/LHC/WhyLHC-en.html

http://lhc.web.cern.ch/lhc/

http://www.lhcountdown.com/

http://www.uslhc.us/LHC_Science

http://public.web.cern.ch/Public/en/LHC/Safety-en.html

http://public.web.cern.ch/Public/en/LHC/WhyLHC-en.html

Documents

Abigail Bickley, Dept of Chemistry, July 25, 2008 Large Hadron Collider