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Fermilab Public Lecture. The LHC Voyage Of Discovery Dan Green Fermilab. What is Particle Physics?. Particle physics is the modern name for the centuries old effort to understand the laws of nature. It aims to answer the two following questions: - PowerPoint PPT Presentation
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1
Fermilab Public Lecture
The LHC Voyage
Of
Discovery
Dan Green
Fermilab
Fermilab Lecture, Sept. 23, 2011
2
What is Particle Physics?Particle physics is the modern name for the centuries old effort to understand the laws of nature. It aims to answer the two following questions:
What are the elementary constituents of matter ?What are the forces that control their behavior at the most basic
level?Physicists continue to ask these questions since they have never
really grown up.
Experimentally:
Make particles interact (accelerators) and study the produced particles. E=Mc2, using collision energy to make new, heavy
particles.
Measure the energy, the direction and the identity of all these reaction products as precisely as possible (detectors).
Fermilab Lecture, Sept. 23, 2011
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What is the Universe Made of?
Early speculation on the building blocks, 500 BC
Fermilab Lecture, Sept. 23, 2011
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Atoms and Simplicity, 1869
All the complexity that we see in the World, with it’s 92 elements, comes from the simplicity of arranging electrons and protons in atoms. The periodic table groups elements with equal number of outer orbital electrons, for example noble gases. Lesson: predictions for missing elements.
Fermilab Lecture, Sept. 23, 2011
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Electrons - 1897
Accelerate in electric field, deflect in magnetic field and observe by having the e interact in a detector – the basic steps. Lesson: We can see electrons with our own eyes!
Fermilab Lecture, Sept. 23, 2011
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Nuclei – Rutherford, 1908• Rutherford established the
structure of the atom • by scattering particles off
the atoms, • seeing wide angle
deflections in a detector• Lesson: infer structure by
scattering. • Atoms have small, positively
charged nuclei, 100,000 times smaller than the electron distribution!
• Students and scintillation……
Fermilab Lecture, Sept. 23, 2011
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Going Smaller and SimplerNuclei are all made up of just neutrons and protons. Looking more closely, they in turn are made up of quarks. Quarks are fundamental ! ?
To look closer we need higher energies. We use E = mc2 (Einstein) and we quote mass in energy units.
Fermilab Lecture, Sept. 23, 2011
What are the Forces ? - Gravity
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“Of Newton with his prism …. A mind for ever voyaging through
strange seas of thought”.
Sir Isaac Newton
“I seem to have been only like a boy playing on the seashore, and
diverting myself in now and then finding a smoother pebble or a
prettier shell than ordinary, whilst the great ocean of truth lay all
undiscovered before me.”
Lesson: gravity is universal – on earth (apples) as in the heavens
(satellites) – a unification!Fermilab Lecture, Sept. 23, 2011
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Electricity-Magnetism
Maxwell in 1862 unified electricity and magnetism, and in so doing predicted a wave going at the speed of light, thus explaining light. Lesson: unification may predict new phenomena.
Fermilab Lecture, Sept. 23, 2011
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The “Weak” InteractionCurie in 1895 discovered that the elements were not eternal and indivisible, but changes occurred by “radioactive decay”. Elements can be transmuted !
Much later, 1982, we found that the weak interaction and the electromagnetic were unified. Lesson: forces tend to unify at high energies/temperatures or short distances .
Fermilab Lecture, Sept. 23, 2011
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Interactions in the Standard Model
Matter particles interact via the exchange of force particles
Fermilab Lecture, Sept. 23, 2011
boomerang?
Nuclei- need a strong interaction to overcome coulomb repulsion of the protons. “Gluons” are the force carriers
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The “Standard Model” - SMM
atte
r Pa
rtic
les Force Particles
Fermilab Lecture, Sept. 23, 2011
You are here
All force carriers, photon (EM), gluons (strong), gravitons (gravity) are massless EXCEPT the W,Z (weak force) – why is that? The LHC was designed to find the answer.
Predictions:b, t, vτ seen at Fermilab
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Is the SM the End of the Story?In the SM all particles have no mass, like the photon, and move at the speed of light! Not… So we postulate the “Higgs boson” which gives mass to each particle of the SM.Without a Higgs boson, our calculations for collisions begin to fail at a mass around 1 Trillion eV (TeV). This defines the “terascale” of mass – the TeV scale – where new Physics must emerge.The Higgs by itself is not enough. Postulate a “super-symmetry” to solve the remaining problems of the Higgs. What about our inability to incorporate quantum gravity? Postulate 10 dimensions! More later.What about Dark Matter and Dark Energy – which are 96% of the Universe by weight? No Standard Model particles exists to explain them. Oh my!
Fermilab Lecture, Sept. 23, 2011
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Why the LHC ? Many of the Standard Model problems point to the mass scale of 1 TeV. The Large Hadron Collider, LHC, at CERN, in Geneva Switzerland was designed specifically to decisively confront that mass scale.It is Large, 26 km circumference, uses Hadrons, protons in this case, and it is a Collider, bashing protons on protons head on = LHC.
Fermilab Lecture, Sept. 23, 2011
Geneva airport
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Particle Accelerators and the LHC
de Broglie
High energies allow us:
To look deeper into Nature (E 1/size), (“powerful microscopes”)
Einstein
To discover new particles with high(er) mass (E = mc2)
Boltzmann
To study the early universe (E= kT)
Fermilab Lecture, Sept. 23, 2011
Revisit the earlier, hotter, history of our Universe , searching for a new simplicity (“powerful telescopes”) by observing phenomena and particles no longer observable in our everyday experience.
The History of Our Universe
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proton-proton collisions at the LHC correspond to conditions here; time, temp and energy. The LHC is a time machine!
Fermilab Lecture, Sept. 23, 2011time
energy,temp
The LHC Beams are Energetic
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The LHC and its experiments are arguably the most complex scientific instruments ever built – of necessity if we are to confront the TeV mass scale decisively.
The energy stored in the LHC beams would melt 1T of Cu. This is 200 times the Tevatron total beam energy. The energy in the magnets would melt 50T of Cu. Caution is needed.
Fermilab Lecture, Sept. 23, 2011
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The LHC is a Big Step in Mass
Fermilab Lecture, Sept. 23, 2011
The gain in “mass reach” is not just the factor of 3.5 in proton energy w.r.t. Tevatron. At the interesting TeV mass scale the reaction rate is a factor at least 10000 x greater at the LHC than at the Tevatron. Truly, the LHC is a machine for discovery, aimed at the TeV mass.
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LHC Accelerator - Poised for Discovery
The LHC at 1.9 K is colder than the CMB
• The LHC is the highest energy collider in the world
• The LHC has the worlds largest cryogenic plant.
• The LHC is designed to have the highest reaction rate of any collider, design value is 1 GHz.
wrt Tevatron (at design)Energy x 7 Reaction rate x 20Large increase -> discovery
Fermilab Lecture, Sept. 23, 2011
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World’s Largest Cryogenic Plant
Deep space is at 2.3o above absolute zero. LHC operates at 1.8o to achieve a higher magnetic field. If normal magnets used, size would be 4x and power used would be 40x!
Fermilab Lecture, Sept. 23, 2011
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Extremely High Vacuum
“Store” beams for ~ 10 hours. Protons travel ~ 10 billion km around the LHC ring ~ round trip to Pluto -> need a good vacuum
Fermilab Lecture, Sept. 23, 2011
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It’s Difficult – Rare Processes
At design operation, there are 1 billion interactions per second to examine. In order to decisively study the 1 TeV mass scale, we need to examine a total of 10,000 trillion interactions. We are only 1 % of the way there at present and at ½ the design energy. We are just starting the long voyage.
Fermilab Lecture, Sept. 23, 2011
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ATLAS and CMS – at the Leading Edge
Each detector is like a 100 megapixel camera which takes 40 million pictures per second. The largest and most complex scientific instruments ever built.
Fermilab Lecture, Sept. 23, 2011
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World’s Largest Collaborations
There are 4 experiments at the LHC. The 2 general purpose detectors, ATLAS and CMS, have formed the largest scientific collaborations ever attempted. They function well because they have a common language and goals – Physics.
Fermilab Lecture, Sept. 23, 2011
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The CMS Collaboration
CMS CollaborationUSAAustriaBelgiumFinland FranceGermanyGreeceHungaryItalyPolandPortugalSlovakiaSpainCERNSwitzerlandUKRussiaArmeniaBelarusBulgariaChinaCroatiaCyprusEstoniaGeorgiaIndiaKoreaPakistanTurkeyUkraineUzbekistan
31 Countries146 Institutes1801 Physicists and Engineers
The US is the largest national group in CMS – about 1/3. FNAL is the second largest group in CMS, second only to CERN. FNAL is also the host for US CMS
It takes a collaboration of this size to fully address the physics.
Fermilab Lecture, Sept. 23, 2011
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US Physics and the LHC
Fermilab Lecture, Sept. 23, 2011
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CMS – Timeline, “Laying the Keel”
It took almost 20 years to design, construct, test, install and commission CMS with a very large team of scientists and engineers. 1993 - 2003
Fermilab Lecture, Sept. 23, 2011
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CMS Magnet
The most expensive single device in CMS. The world’s largest solenoid.
Fermilab Lecture, Sept. 23, 2011
The magnet is like a prism – bending the particles with more energy by less.
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Precision Tracking
200 m2 of Si with 75 million channels. A factor > 10 increase in complexity w.r.t. previous experiments. Spatial resolution of 0.0008 “ precisely determines particle trajectories in the magnet and therefore energies.
Fermilab Lecture, Sept. 23, 2011
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Crystals – Energy Measurements
More than 60,000 crystals manufactured with <1 % tolerances in response. Needed for precise, redundant measurement of electron energies.
Fermilab Lecture, Sept. 23, 2011
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Data Analysis -It Takes a “Grid”
Fermilaboperates the national computing center for US CMS
CMS produces 1 million DVD of data per yearFermilab Lecture, Sept. 23, 2011
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How Do FNAL Physicists Participate?
CMS is 4500 miles away. Can we ‘do physics” here? Yes indeed, all physicists are “remote” . At CERN you are 20 km away and the detector is 100m underground and inaccessible. We built the “Remote Operations Center” – ROC - and the “LHC Physics Center” - LPC. Stop by during the reception!
The sun never sets on CMS. ROCs at CERN, DESY/Hamburg, FNAL and IHEP/Beijing.
Fermilab Lecture, Sept. 23, 2011
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Underground Experiment Cavern
Late 2004 the “dry dock”
100 m underground
Fermilab Lecture, Sept. 23, 2011
Spectacular Operations – “The Launch”
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World’s Largest Solenoid
4 T, 3 GJ~ 600 kg of TNT stored energy
Feb., 2007
Fermilab Lecture, Sept. 23, 2011
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The Press Was There
Fermilab Lecture, Sept. 23, 2011
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Looking Back in Time at the LHC
We make, in a tiny region of space, interactions at temperatures a million times hotter than the center of the sun. These temperatures correspond to a time a billionth of a second after the big bang. To set the scale, one TeV is the energy of a flying mosquito – but concentrated into a region of space 10,000 billion times smaller. An enormous energy density.
Fermilab Lecture, Sept. 23, 2011
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“The Shallows” – Shakedown Cruise
In 2010, CMS measured all the particles of the Standard Model – some shown here
??
Fermilab Lecture, Sept. 23, 2011
19601970
1980
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Into “Deep Waters”
Fermilab Lecture, Sept. 23, 2011
For every 10,000,000 W events produced you make at most 1 Higgs, which can then decay into 2 Z bosons, for example. It is still early days.
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Higgs Decay to Z+Z?What a Higgs decay into 2 Z bosons which subsequently decay into 2 muons each would look like in CMS
Fermilab Lecture, Sept. 23, 2011
http://lbne2-docdb.fnal.gov /0040/004099/002
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Into Uncharted Seas
Once past the “shallows” and on into the deeps, what strange beasts may appear….
Terra incognitaFermilab Lecture, Sept. 23, 2011
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Dark Matter ?
There is no known candidate for Dark Matter. Dark Matter is a stable, neutral relic particle from the earliest moments after the Big Bang – wonderful new physics.
~ , ~ 1/v r v r
Fermilab Lecture, Sept. 23, 2011
You are here
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Dark Matter and Colliding Galaxies
Galaxy has a visible component and a dark component which interacts only gravitationally. Colliding galaxies show the different interactions of the neutral Dark Matter and the visible matter, which has Electromagnetic interactions.
Fermilab Lecture, Sept. 23, 2011
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Dark Matter Searches -“Full Court Press”
Produce it Scatter it Observe it LHC FNAL annihilate
These 3 could converge, making a tremendous scientific breakthrough
Fermilab Lecture, Sept. 23, 2011
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Super - Symmetry (SUSY)The lightest SUSY particle (LSP) is stable and would explain Dark Matter . A LSP mass of ~ 1 TeV yields the observed relic abundance of Dark Matter particles, 23 % !
SUSY also predicts the Grand Unified Theory (GUT) of forces where the 3 Standard Model forces unify at very high energies..
Fermilab Lecture, Sept. 23, 2011
SUSY doubles the number of particles. Each Standard Model particle has a partner
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SUSY at LHCFor all the good features, many physicists like SUSY – but Nature is the final arbiter. A typical SUSY pair in CMS would have large unbalanced momentum (LSP escapes without leaving energy in CMS). Limits at the LHC are approaching 1 TeV. Stay tuned !
Fermilab Lecture, Sept. 23, 2011
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Gravity and SM Forces
A completely naïve classical extrapolation of gravity comes close to the GUT mass scale. Is that a hint of more unification?
100 years after GR (Einstein), it appears that point particles are not possible, but rather strings existing in many (10) dimensions, with those > 4 curled up into tiny size.
Gravity is very, very weak – a small magnet can overcome the whole Earth and pick up a nail. Is that because gravity spreads out and dilutes in the additional dimensions?
Fermilab Lecture, Sept. 23, 2011
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Gravity ? – Not in the SM• Extra dimensions ?• Are those dimensions observable? At the LHC we will look for
extra dimensions. Perhaps we can push a particle to disappear into the unseen dimensions.
• We are presently setting limits on the mass scale of a few TeV
Fermilab Lecture, Sept. 23, 2011
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Forces and Unification
Quantum Gravity
Super Unification
Grand Unification
Electroweak Model
QED
Weak Force
Nuclear Force
Electricity
Magnetism
Maxwell
Short range
Fermi
QCD
Long range
Short range
Terrestrial Gravity
Celestial Gravity
Einstein, NewtonGalilei
Kepler
Long range
?
Universal Gravitation
Electro magnetism
Weak TheoryStandard
model
Theories: STRINGS? RELATIVISTIC/QUANTUM CLASSICAL
SU
SY
?
GUTTOE
Energy
“We shall not cease from exploration and the end of all our exploring will be to arrive where we started and know the place for the first time….A condition of complete simplicity….And all shall be well.” – T.S. Eliot
The LHC program “has legs”. In 2014 the energy will double, opening up a higher mass reach. The interaction rate is planned to increase 10 fold, allowing study of rarer processes – a 25 year program of research has begun.
Fermilab Lecture, Sept. 23, 2011
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Well Documented – Read More
Fermilab Lecture, Sept. 23, 2011
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Terascale Incognita
We have arrived in “terascale incognita”. The exploration of the TeV mass scale is well underway. By the end of 2012 many possible new phenomena will have been examined decisively. Remember: “Nothing is too wonderful to be true if it be consistent with the laws of Nature” – Michael Faraday.
SM
Fermilab Lecture, Sept. 23, 2011
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HEP Invented WWW
Fermilab Lecture, Sept. 23, 2011
Elements of Innovation in Science
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Large science projects push innovationSpace: Apollo mission, space station, voyagerParticle physics: accelerators in generalAt CERN: LEP, LHC
Pushing the limits of what is possible. CERN examples: Magnetic fields, vacuum, precision alignment, cryogenicsTransport, displacement of very heavy equipmentHigh density radiation-tolerant silicon detectorsLarge scale industrial control systemsElectronics and computing systemsProject management and coordination
Fermilab Lecture, Sept. 23, 2011
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Spinoffs - Accelerators
Magnets (MRI), Superconducting coils, accelerators (e.g. Loma Linda p therapy). Light sources
Fermilab Lecture, Sept. 23, 2011
Accelerators developed in labs are used in hospitals
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Courtesy of IBA
Around 9000 of the 17000 accelerators operating in the World today are used for medicine.
Example: Hadron TherapyFermilab Lecture, Sept. 23, 2011
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Pathway of an Innovation
Radionuclides used in PET scanning are produced by cyclotrons in hospitals – glucose labeled with positron emitters e.g. Fluorine 18.PET cameras today use APDs (and Si PMs) and heavy scintillating crystals and starting to be combined with MRI scanner.
The scientific basis for all medical imaging (functional & physiological) are steeped in nuclear/particle physics
1928: description of electrons consistent with Einstein’s special theory of relativity and quantum mechanicsPredicted existence of anti-particles (e.g. positron - basis of Positron Emission Tomography (PET)) and explained spin (- basis of Magnetic Resonance Imaging (MRI))1932: Operation of first cyclotron , the anti-electron (positron) discovered
Fermilab Lecture, Sept. 23, 2011
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Relevance of Fundamental Physics
Early 20th century: Einstein’s insightLight waves consists of packets of energy (photons)
Laws of lasing1960: First laser made to operate - “a solution looking for a problem”
Today’s high bandwidth communication uses laser light signals through optical fibres (last year’s physics Nobel Prize)
Snippets from the Ancestry of Particle PhysicsMatter of our everyday experience is made up of elementary particles
– quarks (up & down) and electrons
1893: JJ Thomson discovers the electron1947: First semiconductor transistor
Today our world turns using “electronics”
Advances in fundamental science drive advances in technologies that alter the way we live
Fermilab Lecture, Sept. 23, 2011
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Neutrinos
Fermilab Lecture, Sept. 23, 2011
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LHC May Answer Large Questions
Quarks + leptonsPhotons, gluons, W and Z
Higgs ?Super symmetry ?Extra Dimensions ?
Fermilab Lecture, Sept. 23, 2011
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HEP Connections to Cosmology
Can we make DM at the LHC?
Extra Dimensions?Super symmetry?
Fermilab Lecture, Sept. 23, 2011
61Fermilab Lecture, Sept. 23, 2011
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Unification - Schematic
Fermilab Lecture, Sept. 23, 2011
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The Forces are Carried by Particles
Fermilab Lecture, Sept. 23, 2011
64Fermilab Lecture, Sept. 23, 2011
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Present Higgs Search
After looking at “only” 100 trillion interactions we are beginning to rule out a Higgs boson which has a mass of particular values. We will push onward in 2011 and 2012.
Fermilab Lecture, Sept. 23, 2011
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LHC Data in 2010 and 2011Commission CMS by finding all SM particles. Start in the “shallows”.
Fermilab Lecture, Sept. 23, 2011
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Limits to Date
Limits are approaching 1 TeV, where SUSY needs to exist if it is to stabilize the Higgs mass.
Fermilab Lecture, Sept. 23, 2011
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10-5
100
105
1010
1015
1020
10-6
10-5
10-4
10-3
10-2
10-1
100 Standard Model Forces and Gravity, Running Coupling Constants
M(GeV)
Forcestrength
energy
GUTSUSY
gravity
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The Forces in the Standard Model
All force carriers, photon, gluons, gravitons are massless EXCEPT the weak force carriers – why is that? The LHC was designed to find the answer.
Fermilab Lecture, Sept. 23, 2011
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The LHC is a Big Step in Quark/Gluon Energy
At the interesting TeV mass scale the reaction rate is a factor at least 1000 x greater at the LHC than at the Tevatron, all else being equal. Truly, the LHC is a machine for discovery, aimed at the TeV mass.
Fermilab Lecture, Sept. 23, 2011
Mass Scale
100,000
LHC at CERN in Geneva
A proton – proton collider, 27 km in circumference. Beams of 7 + 7 TeV protons colliding 40 million times per second
100m underground
W,Z Data – Tie in to Tevatron
All force carriers, g, γ, W and Z were quickly commissioned in CMS in 2010
Top Cross Section
Note the rapid rise from Tevatron to LHC by a factor ~ 20. The LHC is therefore a “top factory” and precision top measurements become possible at the LHC.
Dark Energy and Higgs v.e.v.
2 5 2 3
3
14
4
14
3 / 8 1.05 10 ( / )
~ 5.6 /
2 10 *
~~ 0.0024
~ 174 , ~ 10
c o N
c
c
DE
EW
H G x h GeV cm
p m
c x GeV cm
eV
GeV ratio
The measured dark energy is consistent with a vacuum field or a “cosmological term” in General Relativity of 2.4 meV. In contrast the Higgs v.e.v. is 174 GeV which is a spectacular mismatch. Clearly, we do not understand the “vacuum”. Therefore, focus on dark matter for now in HEP.