Magic of Muons: How a magnet from the 90’s could usher in a new age of physics
Joe Grange Argonne National Laboratory [email protected] To d ay
‣ Broad introduction to particle physics - what are we doing? why?
‣ The amazing muon as a tool for science and society
‣ History and future of “g-2” measurements - how an old magnet could revolutionize the field
‣ Wrapup
2 ‣ Broad introduction to particle physics - what are we doing? why?
‣ The amazing muon as a tool for science and society
‣ History and future of “g-2” measurements - how an old magnet could revolutionize the field
‣ Wrapup
3 Physics in a nutshell
‣ Broadly, here at Fermilab and around the 1 mm world we try to understand the world in terms of it’s most basic building blocks and how they interact 3x10-7 mm
1x10-7 mm
1x10-12 mm
< 1x10-15 mm
4 Incredible richness in the sensory world arises from just a few particles
‣ Very small number of ingredients form everything you can see, feel or touch: p n e
γ"
5 Amazing variety from such simple ingredients
6 Amazing variety from such simple ingredients
7 19th century hubris
“In this field, almost everything is already p discovered, and all that remains is to fill a few unimportant holes.” (1878) Johann Philipp Gustav von Jolly advising Max Planck n not to pursue physics e
1918 γ"
8 Good thing Planck didn’t listen...
‣ His theory not only described never before seen phenomena, it revolutionized the fundamental description of the atom von Jolly was so happy with!
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9 Since then...
‣ An incredible revolution in theoretical physics - quantum mechanics Everything we know about the - special relativity (E=mc2) universe is based on these fundamental - general relativity (mass distorts space-time)particles and their interactions
‣ Complemented by leaps and bounds in experimental techniques - allowed for discovery of “particle zoo”, new forces and confirmation of the intricacies of quantum mechanics
Today: μ’s
‣ Ultimately led to the formation of the foundation of particle physics. 1970’s: the Standard Model
10 What’s a muon?
‣ Essentially a heavy electron. Almost identical in it’s nature with important distinctions: - 200 times the electron mass - lives for only 2 millionths of a second
μ e ν ν
11 Discovery of the muon
‣ 1936: observation of muons originating in cosmic rays
Pike’s Peak, CO circa 1936 cloud chamber
‣ This is the primary reason neutrino experiments usually go deep underground: we “hide” from these cosmic muons that can confuse our detectors
12 Discovery of the muon
Seth Neddermeyer Can you spot the muon in these original cloud chamber photos? Hint…they make thicker tracks
Carl Anderson
1936
13 Discovery of the muon
Seth Neddermeyer Can you spot the muon in these original cloud chamber photos? Hint…they make thicker tracks
Carl Anderson
1936
14 ‣ Broad introduction to particle physics - what are we doing? why?
‣ The amazing muon as a tool for science and society
‣ History and future of “g-2” measurements - how an old magnet could revolutionize the field
‣ Wrapup
15 Muons all around (and through) us
‣ Extra-galactic protons and neutrons collide with the Earth’s atmosphere to create an enormous particle shower - active area of research to understand the origin of these protons and neutrons ‣ Most particles either decay or stop in the atmosphere...
‣ Muons live long enough to make it to Earth’s surface. Only possible by special relativity!
16 Special relativity: “moving clocks count slower”
‣ Earth’s atmosphere: ~12000 m high
‣ Mean distance without special relativity: 660 m - d = v * t - 660 m = c * 2.2 μs
‣ Mean distance with special relativity: 13900 m - d = v * γ * t (γ = Lorentz factor) - 13900 m = c * 21 * 2.2 μs (γ = 21 for 2 GeV muon)
17 More specialImmensely relativity valuable tool for particle physics: well understood source of free muons, used to calibrate our detectors
‣ 1971: one atomic clock placed on ground, another put on airplane that flew entirely around the globe - difference was 0.000000059s! (predicted by Einstein)
‣ Implication for all unstable particles: the faster you go, the longer you live
‣ Cosmic ray muons travel at 99% the speed of(Discovered light.CDF fundamentalIf not for quark) time- dilation, they wouldATLAS detector decay long before reaching us. detector (helped discover Higgs boson) ‣ Since Einstein was right, at sea level we get about 10,000 muons per MINOS detector square meter per minute(enormous (~500 contributions per to knowledgeminute of throughneutrinos) you!) 18 Broader application: “muography”
‣ Just like x-rays from the Dr.’s office, but cosmic ray muons can travel much farther - can image much larger objects. - they also come for free!
‣ Same principle as light passing through objects and creating a shadow
Standard x-rays use photons, not muons, as a probe Less light passes through: object is more dense
More light passes through: object is less dense
19 Let’s muograph a pyramid ‣ Historical rumors suggest there could be hidden chambers in the one of the great Pyramids of Giza Luis Alvarez Real data Simulated data with hidden chamber No hidden chamber found, historical rumors disproven!
1968 Pyramid of Chephren
Alvarez put muon detector here, observed pyramid structure through muon “shadow”
20 Let’s muograph a volcano
‣ Muons provide a better probe of geological structures than many volcanic structure via muons! conventional methods. Can use to predict when a volcano will erupt! (cross-section view)
Unusually dense area: mound of lava from 2004 eruption Mt. Asama, Japan
21 Let’s muograph a reactor
‣ Following the disaster in 2011, the Japanese Fukushima reactor is still too radioactive for humans to enter the building. Muon tomography confirmed the reactor suffered a complete meltdown.
22 Generic security applications
‣ Imaging of truck cargo for security purposes
23 ‣ Broad introduction to particle physics - what are we doing? why?
‣ The amazing muon as a tool for science and society
‣ History and future of “g-2” measurements - how an old magnet could revolutionize the field
‣ Wrapup
24 Magnetic moments
‣ A fundamental property of every particle is it’s “spin”: analogous to spinning objects in everyday life.
Magnetic field ‣ By measuring this precession rate (and knowing your magnetic field), calculate it’s magnetic moment. Usually refer to this quantity as g - for gyromagnetic ratio remaining unknown: physics!
q (g 2) = B a m 2
measure
25 q (g 2) = B (some) Measurement details a m 2
‣ Muon spin precession (ωa): measure - electron direction & energy carry information about muon spin at time of decay magnetic field facility at Argonne ‣ come visit! Magnetic field strength (B) - use polarized nuclei spins to detect field ru nstrength-00742/1.bin 9089.7 run-00742/2.bin 9089.8 heart of 2 2 "-" "-" electron detector 1.5 B frequency 1.5 1 1
) 0.5 ) 0.5 V V ( ( 0 0 D D I I
F -0.5 F -0.5
strength (V) strength -1 -1 -1.5 -1.5 -2 -2 0 2 4 6 8 10 0 2 4 6 8 10 Time (ms) Time (ms)
run-00742/3.bin 9089.9 run-00742/4.bin 9089.8 2 26 2 "-" "-" 1.5 1.5 1 1
) 0.5 ) 0.5 V V ( ( 0 0 D D I I
F -0.5 F -0.5 -1 -1 -1.5 -1.5 -2 -2 0 2 4 6 8 10 0 2 4 6 8 10 Time (ms) Time (ms) g-2 measurement history
‣ In last 60 years, technology advancements has allowed enormous progress in experimentally measuring this quantity
‣ Extremely precise measurements: ppm: parts per million. For example, radius of Earth ppm is a few meters.
27 g: Long history of driving discovery
‣ Dirac theory (1930’s): g = 2 for point-like, fundamental particle.
‣ g for proton ~ 5.6! Huge discrepancy. Eventually explained (1960’s) by composite nature of protons + neutrons. - quarks!
‣ 1940’s: g for electron, muon (no quarks inside) not exactly equal to 2. Discovery lead to development of quantum electrodynamics photon (particle of light) electron
28 Let’s build it!
29 Let’s optimize it!
‣ Magnetic field measurement improves with magnetic field homogeneity
30 g-2 at Brookhaven National Lab
‣ Measured this g-2 for muons in 2001, saw interesting difference...
‣ Rises to the level of “interesting”, not discovery. This is the motivation for repeating the experiment at Fermilab (but do better)!
31 What might we find?
Magnetic field
‣ This g number affected by all particles in nature through fundamental fluctuations
‣ Tiny deviations from what we expect could be new particles showing themselves for the first time
32 ‣ Broad introduction to particle physics - what are we doing? why?
‣ The amazing muon as a tool for science and society
‣ History and future of “g-2” measurements - how an old magnet could revolutionize the field
‣ Wrapup
33 Accelerator Experiment FY2010 FY2011 FY2012 FY2013 FY2014 FY2015 Running&Experiments (LHC) (CMS) OtherTevatron muonCDF/DZero experiments at FermilabCCCDecommissioningC/CDataCAnalysis Booster MiniBooNE MainCInjector MINOS 300CkW 700CkW Accelerator Experiment FY2010 FY2011These experimentsFY2012 useFY2013 FY2014 FY2015 MINERvA 300CkW 700CkW Running&ExperimentsCritical piece of every muons produced by SY120 SeaQuest Comm.C/CRunning (LHC) experiment(CMS) neutrino interactions Testbeam Tevatron CDF/DZero to studyCCCDecommissioningC/CDataCAnalysis neutrino DarkCMatter CDMS 4Ckg Booster MiniBooNE properties MainCInjectorAccelerator ExperimentMINOSCOUPP 300CkW4CkgFY2010 FY2011 FY2012 FY2013 700CkWFY2014 FY2015 Running&ExperimentsCosmicCParticles PierreCAugerMINERvA 300CkW 700CkW New&ProjectsSY120(LHC) SeaQuest(CMS) Comm.C/CRunningUses pairs of muons CDV1 CDV2 CDV3 CDV4 TevatronBooster MicroBooNECDF/DZeroTestbeam to studyCCCDecommissioningC/CDataCAnalysis proton and CDV0 CDV1 CDV2C/C3a DarkCMatterBooster MiniBooNECDMSMu2e 4Ckg neutron structure MainCInjector MuonCgV2COUPPMINOS 4Ckg300CkW 700CkW CosmicCParticlesMainCInjector PierreCAugerMINERvANOvA 300CkW CDV4 700CkW New&ProjectsSY120 SeaQuestLBNE CDV0 Comm.C/CRunning CDV1 CDV2 CDV3a BoosterNML MicroBooNETestbeam CDV1 DirectlyCDV2 usesCDV3 muons to study CDV4 DarkCMatterProjectCX Mu2eCDMS CDV04Ckg CDV0CDV1nature through CDV2C/C3aCDV1 CDVV2 DarkCMatter CDMSC15CkgMuonCgV2COUPP 4Ckg CDV4muonRunning properties CosmicCParticlesMainCInjector PierreCAugerCOUPPC60CkgNOvA Comm. Running CDV4 700CkW New&ProjectsDarkCEnergy LBNEDES CDV0 RunningCDV1 CDV2 CDV3a Booster MicroBooNE CDV1 CDV2 CDV3 CDV4 NML 34 ProjectCX Mu2e CDV0 CDV0CDV1 CDV1CDV2C/C3a CDVV2 DarkCMatter CDMSC15CkgMuonCgV2 CDV4 Running MainCInjector COUPPC60CkgNOvA Comm. Running CDV4 700CkW DarkCEnergy LBNEDES CDV0 RunningCDV1 CDV2 CDV3a NML ProjectCX CDV0 CDV1 CDVV2 DarkCMatter CDMSC15Ckg CDV4 Running COUPPC60Ckg Comm. Running DarkCEnergy DES Running Conclusion Thanks for listening!
‣ Muons are incredibly important both to society and as a tool for both understanding the fundamental universe
‣ Has driven fundamental discoveries in the past, it may do so again right down the road at Fermilab
35 Extra
36 Other
‣ Magnetic moment measurement of the electron used to measure the parameter that characterizes the electromagnetic (EM) interaction - EM bonds are responsible for holding us and the Earth together! - magnetic moment of the electron most precisely measured quantity in the history of physics
37