Particle Detectors for Hadron Physics Experiments. WS 2011/12 Fr. 12:15 13:45 Jim Ritman, Tobias Stockmanns

Transcription

1 Particle Detectors for Hadron Physics Experiments WS 2011/12 Fr. 12:15 13:45 Jim Ritman, Tobias Stockmanns

2 James Ritman Raum NB Tel Contacts Tobias Stockmanns Tel Skript:

3 Dates Vorlesung 1 T.Stockmanns Vorlesung 2 J.Ritman Vorlesung 3 J.Ritman Vorlesung 4 J.Ritman Vorlesung 5 J.Ritman Vorlesung 6 J. Ritman (Akad. Feier?) Vorlesung 7 M.Mertens Vorlesung 8 T.Stockmanns Vorlesung 9 T.Stockmanns fällt aus Vorlesung 10 J.Ritman Vorlesung 11 T.Stockmanns Vorlesung 12 T.Stockmanns Vorlesung 13 J.Ritman Vorlesung 14 J.Ritman Besuch von COSY:

4 Literatur W.R. Leo: Techniques for Nuclear and Particle Physics Experiments / Springer, 1994 K. Kleinknecht: Detektoren für Teilchenstrahlung / Teubner, 2005 C.Grupen: Teilchendetektoren / BI WIssenschaftsverlag, 1993 D. Green: The Physics of Particle Detectors / Cambridge University Press, 2000 T. Ferbel: Experimental Techniques in High Energy Nuclear and Particle Physics / World Scientific Singapore, 1991 G. Knoll: Radiation Detection and Measurement / John Wiley, 2002

5 Introduction Sources of radiation Radioactive decay Cosmic Radiation Accelerators Content Interaction of Radiation with Matter General principles Charged particles heavy charged particles electrons Neutral particles Photons Neutrons Neutrinos Definitions Detectors for Ionizing Particles Principles of ionizing detectors Gas detectors Principles Detector concepts

6 Content Semiconductor detectors Semiconductor basics Sensor concepts Different detector materials Readout electronics Scintillation detectors Calorimeters General characteristics Organic materials Inorganic materials Light output response Velocity Determination in Dielectric Media Cerenkov detectors Cerenkov radiation Cerenkov detectors Transition Radiation detectors Phenomenology of Transition Radiation Detection of Transition Radiation Complex Detector Systems Particle Identification with Combined Detector Information Tracking

7 Introduction

8 Cloud Chamber detection of a positron

9 ATLAS Detector

10 The ATLAS Detector

11 The ATLAS Detector

12 Sources for accelerated particles

13 Sources for accelerated particles Natural radioactivity discovered 1896 by Becquerel on Uranium salt (nobel price 1903 together with M. + P. Curie)

14 a, b, g - radiation Radioactive nuclei emit a-, b- or g- radiation magnetic field lead Radioaktive sample in lead block lead a-radiation are helium kernels (2 protons+2 neutrons) g radiation are photons (light) b radiation are electrons or positrons

15 a, b, g - radiation Paper Al Concrete Pb a-radiation are helium kernels (2 protons+2 neutrons) g radiation are photons (light) b radiation are electrons or positrons

16 Cosmic radiation

17 Sources for accelerated particles Cosmic radiation discovered 1912 by Victor Hess by measuring the ioniziation of air in a balloon experiment (nobel prize 1936) Wulf electrometer to measure the ionization The next step was the construction of an air-tight ionization apparatus which could be used during balloon flights and fitted with a sensitive electrometric system which was not influenced by the large fluctuations of temperature occurring in the flights. I used a modification of Th. Wulf's apparatus with walls of zink, thick enough to withstand the excess pressure of one atmosphere and a temperature compensation for the fibre electrometer. Furthermore, I found it very important always to use two or three of the instruments simultaneously in order to avoid errors from instrumental defects.

18 Early day physics Robert Millikan 1925 with his group members on the way to the top of Mt. Whitney with detectors for cosmic radiation

19 primary cosmic rays: Cosmic Rays 90 % protons, 9 % a-particles, 1 % electrons before the use of accelerators cosmic rays were the main source for the detection of new particles like the muon, pion, kaon

20 Neutrino Detectors - SuperKamiokande Neutrino detector 1000 m underground 41.4 m height, 39.3 m in diameter 50,000 tons of purified water 13,000 photomultiplier tubes

21 Neutrino Detectors - SuperKamiokande

22 Neutrino Detectors - IceCube Neutrino detector south pole 5000 photomultiplier tubes 1 km 3 sensitive area m deep in the ice

23 Neutrino Detectors - IceCube

24 Pierre Auger Observatory Measurement of the flux of very high energetic particles (>10 18 ev) Two stations at both sides of the hemisphere Southern side in Argentina operational 1600 water cherenkov detectors on 3000 km 2 4 obersatories for air showers

25 Particle Accelerators

26 Accelerator - Techniques Linear accelerators Elektrostatic RF electric field Induction Ring accelerators RF electric field Induction

27 Electro static accelerators Elektrons emitted from a hot wire Cathode at approx. 10 kv Anode: ground

28 Cockroft-Walton 1932: first nuclear reaction with protons 400 kev Greinacher Cascade High current (100 ma) up to 2 MV Injector for high energy / current accelerator

29 Van de Graaff Isolated strips transport the current Voltage dividers for focussing

30 Tandem van de Graaff Negative charged ions will be accelerated first Foil to rip off some electrons The now positive charged ions will be accelerated up to U = 0 V E = (1+Q)xU U above 10 MV (therefore pressure tank)

31 Restrictions Have to withstand high voltages: Discharge, leakage currents... Up to 2 MV in air, 25 MV in N 2, SF 6

32 RF-linear accelerator Voltage between 2 plates with RF modulated RF-field parallel to velocity Particles only with the right phase of RF: particle bunches Bunch length: l << b l RF /2 Bunch distance: d = n l RF Bunch compression for f a bit above 0. Faster particles will be accelerated a bit less. E

33 Wiederö Linear Accelerator 1928 Acceleration DE = qv sinf Fahraday cage during the wrong polarity Length of drift tube Longest LINAC: 3 km (SLAC)

34 Linear Accelerators Stanford Linear Collider (1989) 3.2 km long Accelerated electrons and positrons Up to 50 GeV Future: Internation Linear Collider

35 Induction Linear Accelerator Current peaks in one of the toroid-coils around the beam Right phase necessary

36 Cyclotron Circular Accelerators Invented 1929 by Ernest Lawrence, Berkeley (nobel prize 1939) original scetch from patent paper

37 Cyclotron 10 cm What limits the maximum energy a (simple) cyclotron can reach?

38 Solutions: Cyclotron and others Isochronous cyclotrons modified B-field for larger radii Synchrocyclotron beam in bunches, modified rffield Betatron: Accellerator for eletrons and positrons with a varying magnetic field which keeps the electrons on a circle path and accelerates them via induction

39 1928 Ring accelerator: Betatron Increasing B-field, induction

40 TRIUMF 520 MeV Protonen 18 m diameter Structure permits: - focussing - relativistic energies

41 Synchrotron Like LINAC, but with a B-field (closed ring) rising with (synchronous) the beam momentum. T=1000 MeV protons Br = 5,7 Tm (P=0,3Br)

42 Storage rings (1960) Multiple use of beam (beam heating!) Collider possible (2 storage rings counterrotating) with E cm = 2 E 1, instead of Large storage rings (27 km circumference) LEP 2 x 100 GeV (electrons) till 2002 LHC 2 x 7 TeV (protons) from 2007

43 Two counterrotating particle beams in the same ring or in two seperated rings The two beams collide at the position of the experiments Most prominent example LHC Proton beams with 2 x 7 TeV Complex system of various pre accelerators Collider

44

45 Achievable Energies

46 Discoveries made with the help of accelerators

47 Research Facilities in Nuclear Physics