Slide 1

Physics for Everyone Lecture SeriesFermi National Accelerator LaboratoryMay 4, 2011

Chris Polly, FermilabThe Magic of Muonsm

Chris Polly May 4, 20111The Magic of Muons

Chris Polly May 4, 2011The Magic of Muons2What are muons?What are they good for?Why are they important to Fermilab?m

Chris Polly May 4, 2011The Magic of Muons3protonsneutronselectronsEverything we see, hear, or touch arises from a very basic set of ingredients

pnegphotons (light)

Chris Polly May 4, 2011The Magic of Muons5And spectacular complexity

chemical

biologicalmechanical

Chris Polly May 4, 2011The Magic of Muons6And some not so spectacular effects

Chris Polly May 4, 2011The Magic of Muons7With so much of the world described by atoms & optics, some scholars at the end of the 20th century were jadedprotonsneutronselectronspnegphotons

In this field, almost everything is already discovered, and all that remains is to fill a few unimportant holes. (1878) Johann Philipp Gustav von Jolly advising Max Planck not to pursue physics

1918Chris Polly May 4, 2011The Magic of Muons8protonsneutronselectronspnegphotons

One caveatelectronRadioactive decays in the 1920s appeared to violate energy conservation?!After thesemuons were the next discovered in 1936Chris Polly May 4, 2011The Magic of Muons9protonsneutronselectronspnegphotons

One caveatelectronTo solve the conundrum, Pauli proposed a phantom particlethe neutrino?nneutrinosPostulated in 1930, but not directly observed until 1956After thesemuons were the next discovered in 1936Chris Polly May 4, 2011The Magic of Muons10protons neutronselectronspnegphotonsnneutrinosNeutrinos are fascinating and play a huge role in FNALs past, present, and future

Physics for Everyone Lecture SeriesDavid Schmitz, FermilabApril 6, 2011

Chris Polly May 4, 2011The Magic of Muons11Muons discovered in a rather unlikely place!

Pikes Peak, COChris Polly May 4, 2011The Magic of Muons12Muons discovered in a rather unlikely place!

Pikes Peak, CO

circa 1936 cloud chamberChris Polly May 4, 2011The Magic of Muons13

Carl Anderson

Seth Neddermeyer

Can you spot the muon in these original cloud chamber photos?Hintthey make thicker tracks

1936Chris Polly May 4, 2011The Magic of Muons14Why would they want to take their state of the art equipment to the top of a mountain?

To get closer to the source!Victor Hess

1911-13 electroscope

1936Chris Polly May 4, 2011The Magic of Muons15Cosmic ray research is very active todayMost energetic particle interactions ever observedwhere do they come from?

Fermilab astrophysics group heavily involved in Auger observatory in Argentina (1200 sq. miles) Chris Polly May 4, 2011The Magic of Muons16Simulation of cosmic ray event in Auger

electronsmuonsChris Polly May 4, 2011The Magic of Muons17Simulation of cosmic ray event in AugerelectronsmuonsAuger uses muons produced in cosmic ray interactions to study the cosmic ray interactions themselves!Chris Polly May 4, 2011The Magic of Muons18What are muons?m

Physicists in 1936 were just as puzzledI. I. Rabi

1944Chris Polly May 4, 2011The Magic of Muons19pnegnAnd then a major case of mistaken identity ensued?

Called it the mu-meson

1949Hideki Yukawa

Predicted the existence of a particle that allowed protons and neutrons to communicate. Called it the meson (Greek mesos: intermediate)Andersons muon even had the correct mass as predicted by YukawaChris Polly May 4, 2011The Magic of Muons20pnWe now know Yukawas particle does exist and we call it a pion or pi-mesonppions

In fact, we know much moreprotons, neutrons, and pions are really composed of more fundamental quarks!Chris Polly May 4, 2011The Magic of Muons21pnegnmmuonsWhat are muons?pAs far as we can tell they are exactly like electronsonly 200 times heavier

Chris Polly May 4, 2011The Magic of Muons22pnegnmmuonsMuon/electron similaritiespFundamentaldont seem to be made of parts like protons, and neutronsno spatial extent

Protons made of stuff

Chris Polly May 4, 2011The Magic of Muons23pnegnmmuonsMuon/electron similaritiespThey have the same electrical charge

Chris Polly May 4, 2011The Magic of Muons24pnegnmmuonsMuon/electron similaritiespThey both have spin

Chris Polly May 4, 2011The Magic of Muons25pnegnmmuonsMuon/electron similaritiespSpin precession in a magnetic field

Chris Polly May 4, 2011The Magic of Muons26pIn fact, they were so similar, scientists wondered if muons were electrons in some excited state

e-meg

Level at which muons convert to electronsYearChris Polly May 4, 2011The Magic of Muons27pnegnmmuonsWhere do muons come from?pChris Polly May 4, 2011The Magic of Muons28pnegnmmuonsWhere do muons come from?pIronically, we mainly make them via Yukawas pionsppmn

Chris Polly May 4, 2011The Magic of Muons29pnegnmmuonsWhere do they go?pnenChris Polly May 4, 2011The Magic of Muons30pnegnmmuonsWhere do they go?pThey only live 2 millionths of a second before they decaymChris Polly May 4, 2011The Magic of Muons31What are they good for?m

Muon spin resonanceMuon radiographyMuon catalyzed fusionChris Polly May 4, 2011The Magic of Muons32Muon spin resonancetwo principles

Muon precession faster in stronger magnetic fieldnenmHighest energy decay electrons are emitted in spin direction

Imagine putting a bunch of muons in the same fieldChris Polly May 4, 2011The Magic of Muons33

So by measuring how fast the electron beam rotates, the local magnetic field can be determined

Muon Spin ResonanceSetup at ISISLots of applications for understanding magnetic fields/physics in materials: -magnetoresistance -semiconductors -superconductor -ion mobility -many, many more possibilities Chris Polly May 4, 2011The Magic of Muons34Where are the facilities that do this?

Chris Polly May 4, 2011The Magic of Muons35What are they good for?m

Muon spin resonanceMuon radiographyChris Polly May 4, 2011The Magic of Muons36Muon radiographyEveryone here is familiar with X-ray radiography

Has anyone seen the cat?

First X-ray 1895hand of Wilhelm Rontgens WIFE

Does anyone know what this is?

..a shoe-fitting fluoroscopeChris Polly May 4, 2011The Magic of Muons37Muon radiographywhy use muons?Very penetratingcan X-ray LARGE items

Chephrens pyramid in GisaHow large?Penetrating enough to X-ray a Gisa pyramid in a quest for secret chambers

Chris Polly May 4, 2011The Magic of Muons38Muon radiography

Luis Alvarez

1968

Alvarez installed his detector in this chamberData acquiredSimulated data with chamberChris Polly May 4, 2011The Magic of Muons39Muon radiographyfor securityUses scattered cosmic ray muons

Muons deflect more on high density materials (like Uranium)Big advantagecosmic rays are freeChris Polly May 4, 2011The Magic of Muons40Muon radiographyfor securityTest with 20kg blocks of uranium hidden in a shipping container filled with 10 tons of steel

Chris Polly May 4, 2011The Magic of Muons41What are they good for?m

Muon radiographyMuon catalyzed fusionChris Polly May 4, 2011The Magic of Muons42Why are muons important to Fermilab?m

Chris Polly May 4, 2011The Magic of Muons43

Fermilabs plan for accelerator-based research at the labThese experiments all use muons produced by neutrino interactions to study the neutrinos themselvesnmmneeChris Polly May 4, 2011The Magic of Muons44

Fermilabs plan for accelerator-based research at the lab

This experiment uses pairs of muon to study structure of protons and neutron

Chris Polly May 4, 2011The Magic of Muons45

Fermilabs plan for accelerator-based research at the labThese two are actual muon experimentsthey directly study muons properties and interactions.Chris Polly May 4, 2011The Magic of Muons46Principles of Muon g-2

Pour the wine out of a bottle, is it empty?No, it still has air in it.Pump the air out, so that it is a perfect vacuum, now is it empty?No, it could have light passing through.Assume the bottle is black, now is it empty?Chris Polly May 4, 2011The Magic of Muons47Principles of Muon g-2

Surprisingly, the answer is still no!Even in a perfect vacuum, pairs of particles are continually popping in and out of existencee+e-e-e+e+e-Chris Polly May 4, 2011The Magic of Muons48Whats that got to do with muons?e+e-e-e+e+e-

These virtual particles effectively screen the muons view of the field

The precession frequency will change ever so slightlyChris Polly May 4, 2011The Magic of Muons49Whats that got to do with muons?e+e-e-e+e+e-

The total frequency change depends on how many types of particle there are

Are there undiscovered particles?Chris Polly May 4, 2011The Magic of Muons50Whats that got to do with muons?

The frequency will also change if the muon has structureIs the muon made of something?

Chris Polly May 4, 2011The Magic of Muons51Why do we call it g-2?

g (the gyromagnetic ratio) is essentially this frequency and it would be identically 2 were it not for the virtual particles g=2.00233184Chris Polly May 4, 2011The Magic of Muons52Muon g-2 measured very precisely at Brookhaven National Lab (2001)

TheoryExperimentWould like to bring the apparatus from Brookhaven to Fermilab to improve the precisionChris Polly May 4, 2011The Magic of Muons53Mu2e at FermilabThe Mu2e experiment will continue a long quest of looking for rare decay modes of the muon

Mu2e sensitivityLevel at which muons convert to electronsYearChris Polly May 4, 2011The Magic of Muons54Muon to electron conversion

20 fm 4 fm

1S Muonic AluminumCoherent Conversion (e)

X

e-Nucleus Is Left UnchangedMuonConvertsGraphic by Andrew Norman

Chris Polly May 4, 2011The Magic of Muons55Mu2e solenoidstechnical marvels

Chris Polly May 4, 2011The Magic of Muons56Mu2e solenoidstechnical marvels

pMagneticMirror Effect decays to is captured into the transport solenoid and proceeds to the stopping targets2.5T5TGradient Solenoid FieldPrimary productionoff gold targetGraphic by Andrew Norman

Chris Polly May 4, 2011The Magic of Muons57The biggest muon project everThe Muon ColliderPerhaps the best way to extend our reach at the energy frontier beyond Tevatron/LHCChris Polly May 4, 2011The Magic of Muons58Muon/electron collisions are cleaner Heavy mass of muon allows circular accelerator

Chris Polly May 4, 2011The Magic of Muons59Thank you

very much!