Particle Detectors for Hadron Physics Experiments WS 2011/12 Fr. 12:15 13:45 Jim Ritman, Tobias Stockmanns
James Ritman Raum NB 2-125 Tel. 23556 J.Ritman@ep1.rub.de Contacts Tobias Stockmanns Tel. 02461-61-2591 t.stockmanns@fz-juelich.de Skript: http://www.ep1.rub.de/vorlesungen.html
Dates 14.10. Vorlesung 1 T.Stockmanns 21.10. Vorlesung 2 J.Ritman 28.10. Vorlesung 3 J.Ritman 04.11. Vorlesung 4 J.Ritman 11.11. Vorlesung 5 J.Ritman 18.11. Vorlesung 6 J. Ritman (Akad. Feier?) 25.11. Vorlesung 7 M.Mertens 02.12. Vorlesung 8 T.Stockmanns 09.12 Vorlesung 9 T.Stockmanns 16.12. fällt aus 23.12. Vorlesung 10 J.Ritman 13.01. Vorlesung 11 T.Stockmanns 20.01. Vorlesung 12 T.Stockmanns 27.01. Vorlesung 13 J.Ritman 03.02 Vorlesung 14 J.Ritman Besuch von COSY: 19. 23.12.
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
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
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
Introduction
Cloud Chamber - 1911 detection of a positron
ATLAS Detector - 2007
The ATLAS Detector
The ATLAS Detector
Sources for accelerated particles
Sources for accelerated particles Natural radioactivity discovered 1896 by Becquerel on Uranium salt (nobel price 1903 together with M. + P. Curie)
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
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
Cosmic radiation
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.
Early day physics Robert Millikan 1925 with his group members on the way to the top of Mt. Whitney with detectors for cosmic radiation
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
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
Neutrino Detectors - SuperKamiokande
Neutrino Detectors - IceCube Neutrino detector south pole 5000 photomultiplier tubes 1 km 3 sensitive area 1450 2450 m deep in the ice
Neutrino Detectors - IceCube
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
Particle Accelerators
Accelerator - Techniques Linear accelerators Elektrostatic RF electric field Induction Ring accelerators RF electric field Induction
Electro static accelerators Elektrons emitted from a hot wire Cathode at approx. 10 kv Anode: ground
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
Van de Graaff Isolated strips transport the current Voltage dividers for focussing
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)
Restrictions Have to withstand high voltages: Discharge, leakage currents... Up to 2 MV in air, 25 MV in N 2, SF 6
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
Wiederö Linear Accelerator 1928 Acceleration DE = qv sinf Fahraday cage during the wrong polarity Length of drift tube Longest LINAC: 3 km (SLAC) http://www.sc.ehu.es/sbweb/fisica/elecmagnet/movimiento/lineal/lineal.htm
Linear Accelerators Stanford Linear Collider (1989) 3.2 km long Accelerated electrons and positrons Up to 50 GeV Future: Internation Linear Collider
Induction Linear Accelerator Current peaks in one of the toroid-coils around the beam Right phase necessary
Cyclotron Circular Accelerators Invented 1929 by Ernest Lawrence, Berkeley (nobel prize 1939) original scetch from patent paper
Cyclotron 10 cm What limits the maximum energy a (simple) cyclotron can reach?
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
1928 Ring accelerator: Betatron Increasing B-field, induction
TRIUMF 520 MeV Protonen 18 m diameter Structure permits: - focussing - relativistic energies
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)
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
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
Achievable Energies
Discoveries made with the help of accelerators
Research Facilities in Nuclear Physics