1. 880.A20 Winter 2002 Richard Kass Experimental techniques of High Energy and Nuclear Physics Introduction to detectors discuss a few typical experiments Probability, statistics, and data analysis (Leo, ch 4) distributions, maximum likelihood, least squares fitting, lying Passage of radiation through matter (Leo, ch 2) light and heavy charged particles and photons Scintillation devices (Leo, ch 7, 8, 9) counters and calorimeters, energy measurement Ionization devices (Leo, ch 6) proportional and drift chambers, momentum measurement Semiconductor devices (Leo, ch 10) silicon microstrip detectors, vertexing

2. 880.A20 Winter 2002 Richard Kass References Techniques for Nuclear and Particle Physics Experiments, Leo Particle Detectors, Grupen The Physics of Particle Detectors, Green Detectors for Particle Radiation, Kleinknecht The Particle Detector BriefBook, Bock and Vasilescu http://www.cern.ch/Physics/ParticleDetector/BriefBook Particle Data Book (FREE! ORDER ONE TODAY) http://pdg.lbl.gov Introduction to Experimental Particle Physics, Fernow Statistics for Nuclear and Particle Physicists, Lyons Probability and Statistics in Particle Physics, Frodesen, Skjeggestad, Tofe Statistical Data Analysis, Cowen Statistics, Barlow

3. 880.A20 Winter 2002 Richard Kass Intro to HEP Experiments What are the ingredients of a high energy or nuclear physics experiment? Consider three examples of different types of experiments: FIXED TARGET (FOCUS, SELEX, E791) COLLIDING BEAM (CLEO, CDF, STAR) ACTIVE EXPERIMENT (Super K, SNO) Some Common features: energy/momentum measurement particle identification trigger system data acquisition and storage system software hardworking, smart people… Some Differences: experiment geometry data rate single purpose vs multi-purpose

4. 880.A20 Winter 2002 Richard Kass Fixed Target Experiment Imagine an experiment designed to search for Baryons with Strangeness=+1 These particles would violate the quark model since Baryons always have negative strangeness in the quark model. A candidate reaction is:  - p  k - X + Since this is a strong reaction we need to conserve: baryon number: X has B=+1 strangeness: X has to have +1 electric charge:X has to have Q=+1 General requirements of experiment: we need to know that only k - and one other particle produced in final state To achieve this we will have to: get a beam of  - ’s with well defined momentum (we need an accelerator) get a target with lots of protons (e.g. liquid hydrogen) identify  - ’s and k - ’s eliminate background reaction:  - p   - p measure the momentum of the  - ’s and k - ’s eliminate background reactions:  - p  k - k + n or k - k o p a way to record the data

5. 880.A20 Winter 2002 Richard Kass Simple Quark Model 1960’s duscbt Electric charge -1/32/3-1/32/3-1/32/3 Isospin I z -1/2+1/20000 strangeness00000 charm000+100 bottom00000 topness00000+1 Mesons: pair of quark and anti-quark Baryons: triplets of quarks Quarks are point-like spin ½ objects. Quarks “feel” the strong force, in addition to EM, Weak, and Gravitational forces.

6. 880.A20 Winter 2002 Richard Kass Example of fixed target experiment: FOCUS Real life view Momentum: silicon+drift chambers+PWC’s+magnet Energy: EM+hadronic calorimeters Particle ID: Cerenkov Counters, muon filter calorimeter

7. 880.A20 Winter 2002 Richard Kass CLEO III Experiment General purpose detector to study lots of different final states produced by e + e - annihilations at 10 GeV cm energy Must have cylindrical geometry since beams pass through the detector Must measure: momentum of charged particles energy of  ’s and  o ’s Must identify particles: charged: e, , , k, p neutral: ,  0, k 0,  e+e-B+B-e+e-B+B- B +          s     s        B -  D     D   D    D   K   

8. 880.A20 Winter 2002 Richard Kass Example of active experiment: SuperKamiokande Inside SuperK Original purpose of experiment was to search for proton decay: p  e +  0 Baryon and lepton number violation predicted by many grand unified models (e.g. SU(5)) General Requirements for experiment Need lots of protons (decay rate of 10 32 years  7x10 3 tons of H 2 O) Size: Cylinder of 41.4m (Height) x 39.3m (Diameter) Weight: 50,000 tons of pure water Need to identify e - ’s and  0 ’s Reject unwanted backgrounds (cosmic rays, natural radiation) 10 3 m underground at the Mozumi mine of the Kamioka Mining&Smelting Co Kamioka-cho, Japan

9. 880.A20 Winter 2002 Richard Kass Super Kamiokande Closer look at experimental requirements: Identifying  ’ 0 s tricky since  0  thus must identify  ’s Need to measure energy or momentum of e and  0 impractical to use magnetic field  measure energy using amount of Cerenkov light detect cerenkov light using photomultiplier tubes 11,200 photomultiplier tubes, each 50cm in diameter, the biggest size in the world Energy Resolution: 2.5% @ 1 GeV and 16% (at 10 MeV) Energy Threshold: 5 MeV Need to measure direction of e and  o to see if they come from common point cerenkov light is directional Need to measure timing of e and  o to see if they were produced at common time cerenkov light is “quick”, can to timing to few nanoseconds Nov. 13: Bottom of the SK detector covered with shattered PMT glass pieces and dynodes. BUT DON’T FORGET CIVIL ENGINEERING! Nov 12: accident destroys 1/3 of phototubes

10. 880.A20 Winter 2002 Richard Kass Particle Detection In order to detect a particle it must interact with matter The most important “detection” processes are electromagnetic Energy loss due to ionization electrons particles heavier than electrons (e.g. , , k, p) Energy loss due to photon emission bremsstrahlung (mainly electrons) Interaction of photons with matter photoelectric effect Compton effect pair production (   e + e - ) Coulomb scattering (multiple scattering) Other/combination of electromagnetic processes cerenkov light scintillation light electromagnetic shower transition radiation Calculation of above processes involve classical EM and QED Hadrons ( ,k,p) interact with matter via the strong interaction and create particles through inelastic collisions. These particles lose their energy via EM processes:  0  or  +    +  e 