Solid State Detectors T. Bowcock

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

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

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

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

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

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

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

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

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

11 LEP SC Synchrotron Radiation CERN

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 First major discovery with Solid State Detectors

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

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

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

16 Cloud Chamber

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

18 Emulsion Scale 100  m  First  event

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

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

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

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

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

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...

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

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

27 Spark Chamber HT

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)

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

30 Streamer Chamber 1991 –ions

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

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

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!

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

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?

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?

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

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