2. Solid State Detectors T. Bowcock

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

4. 3 Time and Position Sensors History and Application to Particle Physics Aim –Background –Basic Detector Concepts

5. 4 Chronology of Discoveries Electron (1897) J.J. Thompson Cloud Chamber(1912) C.T.R.Wilson Cosmic Rays(1913) V.F.Hess &C.Anderson Discovery of Proton(1919) E. Rutherford Compton Scattering (1923) C.T.R.Wilson Waves nature of e’s(1927) C. Davisson 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

6. 5 Beginning... 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..." Zinc Sulphide Screen Geiger&Marsden source

7. 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

8. 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) 1932- 1MeV

9. 8 1932-1947 Neutron(1932) J. Chadwick Triggered Cloud Chamber(1932) P.Blackett Muon(1937) S.H. Neddermeyer Muon Decay(1939) B.Rossi, Williams Kaon(1944) L. Leprince-Ringuet Pion(1947).H.Perkins,G.P.S.Occialini 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

10. 9 1947-1953 Scintillation Counters(1947) F. Marshall pion decay(1947) C. Lattes Unstable V’s(1947) G.D.Rochester SemiConductor Detectors(1949) K.G.McKay SparkChambers(1949) J.W.Keuffel K Meson(1951) R. Armenteros 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

11. 10 1953-1968 Neutrino (1953) F. Reines Bubble Chamber(1953) D.A. Glaser K+ Lifetime(1955) L.W.Alvarez Flash Tubes(1955) M. Conversi Spark Chamber(1959) S. Fukui Streamer Chambers(1964) B.A.Dolgoshein MWPC(1968) G. Charpak 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

12. 11 LEP-1984-1999 SC 1957-1990 Synchrotron Radiation CERN

13. 12 1968-1999 J/  (charm) (1974) J.J, Aubert, J.E. Augustin  lepton(1975) M.Perl et al B-mesons(1981) CLEO W,Z(1983) UA1 number of (1991) L3 t-quark(1994) CDF 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 First major discovery with Solid State Detectors

14. 13 Detector Technology 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Cloud Chambers Emulsion Solid State Spark Chambers MWPC Bubble Chambers Drift Chambers

15. 14 Cloud Chamber Supersaturated Gas Cloud formation Used until 1950’s Build your own… Properties

16. 15 Ionisation Charged particles –interaction with material + + + + + + + + + + + + + - - - - - - - - - - - - - - “track of ionisation”

17. 16 Cloud Chamber

18. 17 Emulsion Dates back to Bequerel (1896) Three components –silver halide (600  m thick) –plate –target Grain diameter 0.2  m –Still the highest resolution device

19. 18 Emulsion Scale 100  m  First  event

20. 19 Emulsion Still used –developed –scanned computers help –very accurate –very slow Needs to be combined with active spectrometer

21. 20 Bubble Chamber Superheated Liquid e.g. H 2 –-253C –1954 d=3.4cm –1957 d=180cm Bubbles form around ions 10  m in O(ms) sketch dated January 25th, 1954

22. 21 Bubble Chamber Gargamelle –late 1960’s Volume=12m 3 magnet field –measure p 4  acceptance!

23. 22 Bubble Chamber First Neutral Current Event (Z 0 ) seen in Gargamelle Bubble density measures velocity –  Use limited... Physics Letters, 46B, 138 (1973) –Cannot use in a storage ring –slow cycle time and difficult to trigger

24. 23 Ionisation Important for all charged particles Bethe-Bloch Equation velocity Mean ionisation potential (10ZeV) Density of electrons Problem: Program this yourselves!

25. 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...

26. 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

27. 26 Spark Chambers Gas –see into it Particle tracking Cheap Fast(Pestov) Large Signal

28. 27 Spark Chamber HT

29. 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  m –long memory while ions clear (ms)

30. 29 Streamer Chamber “Electrical Bubble Chamber” Plasma forms along path of particle –streamers move at high velocity –sort pulse leaves visible streamer suspended 40-300  m resolution –triggerable

31. 30 Streamer Chamber 1991 –ions

32. 31 Proportional Tubes Cylindrical tube and wire Near the anode wire large field Run below Geiger Threshold –signal proportional to initial ionisation rara riri + -

33. 32 Multiwire Proportional Chamber (MWPC) Charpak discovered if you put many wires together act as separate detectors.. anodes Cathode plane

34. 33 Signal Generation Note 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!

35. 34 Ramo’s Theorem(1939) quasistatic calculation V1V1 VkVk 1 k q Problem for Students: prove Ramo’s Theorem<1 page

36. 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?

37. 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?

38. 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

39. 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