Solid State Detectors T Bowcock 1 Schedule 1

Solid State Detectors T. Bowcock 1

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

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

Chronology of Discoveries • • • 1900 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 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 4

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

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

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. (80 Ke. V) 1932 - 1 Me. V 7

1932 -1947 • • • 1900 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 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 8

1947 -1953 • • • 1900 Scintillation Counters(1947) F. Marshall pion decay(1947) C. Lattes Unstable V’s(1947) G. D. Rochester Semi. Conductor Detectors(1949) K. G. Mc. Kay Spark. Chambers(1949) J. W. Keuffel K Meson(1951) R. Armenteros 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 9

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

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

1968 -1999 • • • 1900 J/ (charm) (1974) J. J, Aubert, J. E. Augustin t lepton(1975) M. Perl et al B-mesons(1981) CLEO W, Z(1983) UA 1 number of n (1991) L 3 t-quark(1994) First major discovery with Solid CDF State Detectors 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 12

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

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

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

Cloud Chamber 16

Emulsion • Dates back to Bequerel (1896) • Three components – silver halide (600 mm thick) – plate – target • Grain diameter 0. 2 mm – Still the highest resolution device 17

Emulsion m First s event Scale 100 mm 18

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

Bubble Chamber • Superheated Liquid e. g. H 2 – -253 C – 1954 d=3. 4 cm – 1957 d=180 cm • Bubbles form around ions • 10 mm in O(ms) sketch dated January 25 th, 1954 20

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

Bubble Chamber • First Neutral Current Event (Z 0) seen in Gargamelle • Bubble density measures velocity – b <0. 8 • Use limited. . . Physics Letters, 46 B, 138 (1973) – Cannot use in a storage ring – slow cycle time and difficult to trigger 22

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

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

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

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

Spark Chamber HT 27

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

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

Streamer Chamber • 1991 – ions 30

Proportional Tubes • Cylindrical tube and wire • Near the anode wire large field • Run below Geiger Threshold – signal proportional to initial ionisation ra + ri 31

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

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! 33

Ramo’s Theorem(1939) • quasistatic calculation k V 1 1 q Vk Problem for Students: prove Ramo’s Theorem<1 page 34

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

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

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

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