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Instrumentatie: niet moeilijk, wel veel

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Presentation on theme: "Instrumentatie: niet moeilijk, wel veel"— Presentation transcript:

1 Instrumentatie: niet moeilijk, wel veel
Elementary Particles Instrumentation Introduction Dec 15, 2014 Radiation detection Accelerators (Relativity!) Particle Physics experiments Fixed Target experiments Collider experiments astro-particle physics new physics: dark matter Medical radiation: Medical imaging Radiation therapy, beam therapy Nuclear power (fusion, fission) veel demo’s! Instrumentatie: niet moeilijk, wel veel

2 Introduction short history overview The first particles: atoms, electrons, ions The first particle detectors a modern solid-state particle detector

3 History Wimshurst’s electricity generator, Leidsche Flesschen

4 Glazen buizen: gasontlading
Hoogspanning generatoren (Wymhurst), transformatoren (Rumkorff) Ontdekking radiogolven: 1867 Maxwell (theory) 1887 Heinrich Hertz 1887 Marconi Vacuumpompen Beschikbaarheid (zuivere) gassen Marconi

5 First accelerator: cathode ray tube
J.J. Thomson

6 Ee- = q.V (Joule) Ee- = V (eV) Efield = V / D With electron charge q:
F = q . Efield electron kinetic energy: Ee- =  F dD = q.V Ee- independent of: distance D particle mass heated filament distance D Potential diffence V Ee- = q.V (Joule) Ee- = V (eV)

7 ElectronVolt: eV 1 eV = |q| Joules = 1.6 x 10-19 Joules
Energy unit: ElectronVolt: eV 1000 eV = 1 keV 1000 MeV = 1 GeV 1000 GeV = 1 TeV 1 eV = |q| Joules = 1.6 x Joules

8 Van de Graaff accelerator
Vertical construction is easier as support of belt is easier Corona discharge deposits charge on belt Left: Robert van de Graaff From: Principles of Charged Particle Acceleration Stanley Humphries, Jr., on-line edition, p. 222.

9 Faraday Cage! HV = 10 kV gnd belt

10 Lorentz Force - Electrostatic deflection Fe = q. E +
Magnetic deflection: Lorentz force FL = q.v.B Electron beam propagates as straight line if: q/m = E2/(2.V.B2) Constant ratio of mass and charge Definition of electron

11 ? Relativiteit Hoe kan dat nou? v v of twee electronen twee parallel
bewegende electronen ? waarnemer meebewegend alleen statische kracht Lorentz kracht erbij Relativiteit Hoe kan dat nou?

12 Lorentz Transformation
Albert Einstein’s Special Theory on Relativity Speed of light c is invariant for coordinate transformations z’ = z+vt time definition varies with coordinate transformation Snel in te zien via experiment in trein: Klok, gemaakt van twee spiegels. Tweelingparadox Lorentzcontractie trein staat stil trein beweegt t.o.v. stilstaande waarnemer erboven

13 Lorentz Transformation
Albert Einstein’s Special Theory on Relativity Speed of light c is invariant for coordinate transformations z’ = z+vt time definition varies with coordinate transformation

14 From Einstein’s Special Theory on Relativity:
For moving particle (‘system’ of just one moving particle!) Total Energy (of system) = Kinetic Energy + Rest Mass eq. Energy E2 = mo2 c4 + p2c2 [classic: E = ½ mv2 ] With: = v / c, and the Lorentz factor γ: relativistic mass mr = γ m0 γ = 1 / sqrt(1- 2), and  = sqrt(γ2 -1) / γ So: total energy E = m0 c2 sqrt(1+ 2 γ2) [= rest mass energy eq. + kinetic energy] = γ m0 c2 = mr c2

15 Radio activity X-rays Henri Bequerel uranium
Marie Curie radium, polonium Rutherford: Alfa beta gamma rays Photographic emulsion

16 Rutherford, Manchester 1906
First particle detector ZnS scintillator: light flashes visible with naked eye (+microscope)


18 accelerate electrons with a voltage of typically 20 - 100 kV
X-ray tube: accelerate electrons with a voltage of typically kV and stop them in the anode electrons radiate in the strong electric field of the (heavy, e.g. W) atomic nuclei ("Bremsstrahlung") in the anode -> generation of X-rays Most of the energy of the electrons is converted into heat -> anode may need to be cooled (water cooling) and/or to be rotated Low energy X-rays can be removed by passing the X-rays through a suitable material Wilhelm Conrad Roentgen Nobel Prize 1901

19 E = h c/λ ‘high energy physics’
Rutherford atomic model: extreme ratios of E/m Emptyness, nucleon Einstein/Planck E = h ν: Small dimensions High energy Quantum Mechanics Diameter atom: ~ 1 nm Diameter nucleon: ~ 10-4 nm E = h c/λ E: energy h: Planck’s Constant = 6.62 x Js c: velocity of light λ: wavelength Albert Einstein ‘high energy physics’ ‘high’ with respect to ‘classica’l physics

20 CERN, Geneve Higgs’ particle: 100 – 500 GeV !!

21 CERN accelerator complex
to Gran-Sasso (730 km)

22 Natural radioactivity
Uranium, Radon, Thorium ‘induced’ radioactivity: irradiation with neutrons, protons, gamma’s Particle Physics/High Energy Physics experiments accelerators fixed target experiments collider experiments

23 Measurement (detection) of particles
Ionisation radiation Interaction of radiation with matter Fast charged particles transversing matter

24 μ+ μ - π+ π- p e charged particles n π0 γ υ neutral particles

25 Detection of charged (and energetic) particles
muon (b.v.) Energy transfer: mainly to electrons Ionisation: forming elecron-ion pairs

26 Essential (in gas): - creation of electron-ion pairs
- number of clusters per mm tracklength - number of electrons per cluster specific for gas (and density ρ, thus T, P!, and work function W)

27 Ionisation scintillation (followed by light detection) electron-ion pairs: charge separation, charge signals in gas, in semiconductors photographic emulsions: blackening cloud chambers bubble chambers Detection of non-charged (neutral) particles: - conversion to charged particle (e-, proton) - detection of charged particle

28 Scintillation ZnS scintillator viewed by naked eye Rutherford Experiment scintillator Photomultiplier Si avalanche diode

29 Cloud Chambers Bubble Chambers Core for growing droplet or bubble ‘made possible’ by ion or electron

30 Bubble chamber picture showing delta-rays
The red arrows indicate some of the d-electrons, looping in the magnetic field applied CERN photo,

31 Bubble chamber photograph shows different bubble
density along tracks for different particle momenta and particle type.

32 Gaseous Detectors Spark Chamber Passing charged particle detected by sci HV is put over even/odd plates Charge separation (electrons-ions) Electron Avalanche (breakdown, spark) Visible light from exited He/Ne atoms


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