Solid State Detectors. T. Bowcock

Transcription

1 Solid State Detectors T. Bowcock

2 Schedule 1 Time and Position Sensors 2 Principles of Operation of Solid State Detectors 3 Techniques for High Performance Operation 4 Environmental Design 5 Measurement of time 6 New Detector Technologies 2

3 Time and Position Sensors History and Application to Particle Physics Aim Background Basic Detector Concepts 3

4 Chronology of Discoveries Electron (1897) J.J. Thompson Cloud Chamber(1912) C.T.R.Wilson Cosmic Rays(1913) Discovery of Proton(1919) Compton Scattering (1923) Waves nature of e s(1927) V.F.Hess &C.Anderson E. Rutherford C.T.R.Wilson C. Davisson

5 Beginning... Geiger&Marsden source Zinc Sulphide Screen E. Rutherford 1927, Rutherford, as President of the Royal Society, expressed a wish for a supply of "atoms and electrons which have an individual energy far transcending that of the alpha and beta particles from radioactive bodies..." 5

6 Cross-Section 1 barn=10-24 cm 2 approximately the area of a proton Distribution of scattering angles tell us about the force/particles Precision required 6

7 Accelerator technology The first successful cyclotron, built by Lawrence and his graduate student M. Stanley Livingston, accelerated a few hydrogen-molecule ions to an energy of 80,000 electron volts. (80KeV) MeV 7

8 Neutron(1932) J. Chadwick Triggered Cloud Chamber(1932) P.Blackett Muon(1937) Muon Decay(1939) Kaon(1944) Pion(1947) S.H. Neddermeyer B.Rossi, Williams L. Leprince-Ringuet.H.Perkins,G.P.S.Occialini

9 Scintillation Counters(1947) pion decay(1947) Unstable V s(1947) F. Marshall C. Lattes G.D.Rochester SemiConductor Detectors(1949) K.G.McKay SparkChambers(1949) K Meson(1951) J.W.Keuffel R. Armenteros

10 Neutrino (1953) Bubble Chamber(1953) K+ Lifetime(1955) Flash Tubes(1955) Spark Chamber(1959) Streamer Chambers(1964) MWPC(1968) F. Reines D.A. Glaser L.W.Alvarez M. Conversi S. Fukui B.A.Dolgoshein G. Charpak

11 CERN LEP SC Synchrotron Radiation 11

12 J/ψ (charm) (1974) τ lepton(1975) B-mesons(1981) W,Z(1983) number of ν (1991) t-quark(1994) J.J, Aubert, J.E. Augustin First major discovery with Solid State Detectors M.Perl et al CLEO UA1 L3 CDF

13 Detector Technology Cloud Chambers Emulsion Spark Chambers MWPC Drift Chambers Bubble Chambers Solid State 13

14 Cloud Chamber Supersaturated Gas Cloud formation Used until 1950 s Build your own Properties 14

15 Ionisation Charged particles interaction with material track of ionisation 15

16 Cloud Chamber 16

17 Emulsion Dates back to Bequerel (1896) Three components silver halide (600µm thick) plate target Grain diameter 0.2µm Still the highest resolution device 17

18 Emulsion µ First σ event Scale 100µm 18

19 Emulsion Still used developed scanned computers help very accurate very slow Needs to be combined with active spectrometer 19

20 Bubble Chamber Superheated Liquid e.g. H 2-253C 1954 d=3.4cm 1957 d=180cm Bubbles form around ions 10µm in O(ms) sketch dated January 25th,

21 Bubble Chamber Gargamelle late 1960 s Volume=12m 3 magnet field measure p 4π acceptance! 21

22 Bubble Chamber First Neutral Current Event (Z 0 ) seen in Gargamelle Bubble density measures velocity β <0.8 Use limited... Cannot use in a storage ring Physics Letters, 46B, 138 (1973) slow cycle time and difficult to trigger 22

23 Ionisation Density of electrons Important for all charged particles de dx = Dn β e 2 2 2mc β ln I 2 γ 2 β 2 δ ( γ 2 Bethe-Bloch Equation ) Application velocity Mean ionisation potential (10ZeV) Problem: Program this yourselves! 23

24 Ionisation Most of our discussion on minimum ionising paritcles (MIPS) Note essentially the same process in gas, liquid or solid Using ions to nucleate physics/chemical changes need to observe these changes however... 24

25 Ionisation In low fields the ions eventually recombine with the electrons However under higher fields it is possible to separate the charges E Note: e- s and ions generally move at a different rate 25

26 Spark Chambers Gas see into it Particle tracking Cheap Fast(Pestov) Large Signal 26

27 Spark Chamber HT 27

28 Spark Chamber Highly efficient 95% High electron multiplication low electron affinity (Noble gases) high field Problems 30 ns pulses(high voltage spikes) resolution 300 µm long memory while ions clear (ms) 28

29 Streamer Chamber Electrical Bubble Chamber Plasma forms along path of particle streamers move at high velocity sort pulse leaves visible streamer suspended µm resolution triggerable 29

30 Streamer Chamber 1991 ions 30

31 Proportional Tubes Cylindrical tube and wire Near the anode wire large field Run below Geiger Threshold signal proportional to initial ionisation E( r) = V0 V ( r) ln /( r ln( r ( r / r ) + - i a r a r i / r i )) 31

32 Multiwire Proportional Chamber (MWPC) Charpak discovered if you put many wires together act as separate detectors.. anodes Cathode plane 32

33 Signal Generation Note ε = 2 r r qe. dr = q ( Φ Φ ) 1 Change in energy is source of signal Most electrons produced close to anode form of voltage means electrons do not drop much voltage compared with ions that see almost all!

34 Ramo s Theorem(1939) V 1 quasistatic calculation k 1 q Φ i V k Φ i I i,φ 0 r v = q r Ei ( x 1 ) V i Problem for Students: prove Ramo s Theorem<1 page 34

35 Gas Detectors. Many different kinds of gas detectors in use large volume cheap high resolution (down to diffusion levels) lots of experimental results Why do we want Solid State Detectors? 35

36 Detectors Many mature technologies emulsions bubble chambers gas chambers Where next? High resolution reliable 50 years later Si! Question: what are the advantages and disadvantages of each technology? 36

37 Summary Lecture 1 Many types of detectors Use of ionisation from charged particles nucleation separation of charge Signal Generation ideas we will use next lecture 37

38 High Spatial Resolution Detectors Solid State Detectors principles of operation strip detectors drift detectors pixel detectors CCD s advantages and shortcomings methods of fabrication 38