The Precious Life of Muons A seminar by Filippo Capurso as part of - - PowerPoint PPT Presentation

The Precious Life of Muons

A seminar by Filippo Capurso as part of PHY489 - Special Topics in Particle Physics

KAIST – Fall Semester, 2017 1st December 2017

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Overview

• The history behind the muon discovery

and why it is underestimated

• The muons around us

and their properties

• The current uses of muons

and why their properties are valuable

• The potential use of muons in particle

accelerators

and how they could save particle physics

The discovery of the Muon

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The Lord Kelvin

William Thomson, 1st Baron Kelvin

“ There is nothing new to be discovered in physics now. All that remains is more and more precise measurement ”

1900

4 Source: h@p://www.economist.com/blogs/graphicdetail/2012/07/daily-chart-1

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Seth Neddermeyer Carl David Anderson

Based on electron charge data and calculations by Bethe and Heitler, stated the hypothesis of a heavier electron: the Mesotron

Shower of Particles Lead / Platinum Greater ionization than e–

? ? ? 1936

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• J. C. Street and E. C. Stevenson’s Cloud Chamber

h@ps://journals.aps.org/pr/pdf/10.1103/PhysRev.49.425

A shower produced by a single electron A complex shower phenomenon

1937

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h@ps://journals.aps.org/pr/pdf/10.1103/PhysRev.52.1003

The path of a proton Paths of a muon

1937

• J. C. Street and E. C. Stevenson’s Cloud Chamber

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1935

Hideki Yukawa

Predicted particles ~200 times heavier than an electron to explain the nuclear force and named them “mesons”. The muon was therefore considered as the predicted meson.

1947

César La@es, Giuseppe Occhialini and Cecil Powell discovered the real Yukawa particle, the π-meson. The muon was differentiated by it with the name µ-meson.

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1970s

With the definition of the Standard Model, the muon is removed from the handron and meson list, and finally recognised as a fundamental particle, a lepton.

After almost 40 years!

Muon characteristics’ summary

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• 1. Was destined to be ignored and

underrated

• 2. Is a fundamental particle (not

composed by quarks)

“ Who ordered that? ”

Israel Isaac Rabi

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Nature and Properties

The muons around us

µ– µ+

Mass m = 105.6583715 ± 0.0000035 MeV ( ≈ 206.8 times the mass of e–) Charge = –1 q Spin = ½ Mean life τ = (2.1969811 ± 0.0000022) µs

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π0 γ + γ π+ µ+ + νµ π– µ– + νµ

µ+ e+ + νe + νµ µ– e– + νe + νµ

Sources of cosmic ray muons

(99.9877%)

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Sources of cosmic ray muons

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Pion mean lifetime τ = 26.02 ± 0.04 ns Muon mean lifetime τ ≈ 2.197 µs Speed of Light c ≈ 299’792’458 m/s

Max total distance = V · t ≈

666.44 m

But muons fall hit the earth surface at an average rate close to 10’000 particles per m2 per minute

How??

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Applying Relativity laws

K = γ·mc2 + mc2

Kinetic Energy Ratio with speed of light

γ = 1 √(1 – β2) β = v/c β ≈ 0.994 ± 0.005 K ≈ 2 GeV

Time Dilatation Length Contraction

t’ = γ·t l’·γ = l L = v·t’

Found to travel on average between 8.7 km and 15 km

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Why do muons pass through bodies so easily?

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Muon characteristics’ summary

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• 1. Was destined to be ignored and underrated
• 2. Is a fundamental particle (not composed by

quarks)

• 3. Has a short lifetime, but can travel far at speeds

approaching c

Current uses of muons

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Geophysical radiography ScaZering tomography

Heavy material detection and body density analysis

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Geophysical radiography using cosmic ray muons

Illustration of cosmic ray muons entering the Giza Pyramid (Egypt) Longitudinal section of Agua Negra tunnel (Chile)

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Geophysical radiography using cosmic ray muons

Detection of muons passing through La Soufrière of Guadeloupe (France) Change in muon flux passing through the Asama volcano (Japan)

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Scattering tomography for heavy material detection

Prototype of a muon sca@er detector (Italy) Diagram of muon sca@ering when passing through a high density body

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Scattering tomography for heavy material detection

Set up for sca@ering tomography of the Fukushima Daiichi (Japan)

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Scattering tomography for heavy material detection

Identification of a lead body in a car

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Scattering tomography for structure analysis

Tomography of a valve in its two states Tomography of a mock-up of the cupola wall

• f Santa Maria del Fiore (Italy)

Muon characteristics’ summary

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• 1. Was destined to be ignored and underrated
• 2. Is a fundamental particle (not composed by

quarks)

• 3. Has a short lifetime, but can travel far at speeds

approaching c

• 4. Is affected only minimally by external factors

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The Muon as the saviour of Experimental Particle Physics

The limit of Particle Accelerators

• We reached a stop in Experimental Particle Physics
• The last particle of the Standard Model took more than

50 years to be discovered

• But there are still several

unanswered facts and questions Ø Byron Asymmetry: why is there more ma@er than antima@er? Ø Dark Ma@er: where is it and what is it? Ø Neutrino mass problem: why are they so light? Ø Quantum nature of gravity: gravitons? Ø And more…

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There are several theories, but they have to be proved experimentally

Large Hadron Collider (France-Swi\erland)

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Numbers of the world’s largest particle collider

The reachable energy in particle colliders is proportional to two things:

• R = the radius of the accelerator
• B = the strength of the magnetic field

Large Hadron Collider

≈ 2.93 km 8.3 Tesla The LHC managed to accelerate protons up to 6.5 TeV

Record collisions

• f 13 TeV

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The truth about collisions energy

The LHC uses heavy stable particles:

Protons

But protons, being hadrons, are made up of quarks and lose energy when breaking upon impact

Collision with energy loss

Clean collisions are obtained when colliding

leptons as they do not break in their sub-components The heaviest fundamental particles are electrons and

positrons

Lower acceleration

Having a mass 1836 times smaller than the proton mass, they are exposed to synchrotron radiation

0.114 TeV

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• Need a new particle that we

have not yet considered

• Must create clean collisions
• Must be able to remain

stable until collision

• Is not affected by

synchrotron radiation

1. Was destined to be ignored and underrated 2. Is a fundamental particle (not composed by quarks) 3. Has a short lifetime, but can travel far at speeds approaching c 4. Is affected only minimally by external factors µ

A new alternative!

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A new type of collider: The Muon Collider

At 6.5 TeV, a muon would be able to live for 135’000 microseconds Would be able to circle the LHC

1500 times!

Muon Ionization Cooling Experiment

Conclusion

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• 1. Is underrated because of its history
• 2. Was the second fundamental particle to

be ever discovered

• 3. Proves relativity constantly by reaching

the Earth’s soil

• 4. Thanks to its material penetration

characteristics, can be used to monitor and improve the world around us

• 5. Could be the saviour of experimental

particle physics

µ±

1. 2. 3. 4. 5.

Thank you for your attention! Ask Questions J

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