High Energy Experiment Detector

1. HEP High Energy Experiment Detector 2010. 5. 18 Kihyeon Cho

2. Global Sketch of HEP Experiment Determine Physics Goal Simulation Study Beam/Detector Decide subdetectors Electronics R&D Subdetector R&D Software R&D Beam test Readout Trigger(hardware) Simulation code Trigger(software) Rawdata recording Data reconstruction Skimming/MDST Analysis tools Database Caliibration Monitoring System Integration Cosmic rays Beam commissioning System debugging System Calibration Data Taking Momentum/Energy/Mass PID/Lifetime/BF Resolution/Efficiency/background Systematic study Data Analysis Publish Results

3. Particle Accelerator

4. Particle Accelerator

5. Experiments related to CKM parameters e+e- B Factories Major experiments ongoing, some ended Talk by Elisabetta Barberio

6. 전자-양전자 충돌 가속기 실험

7. Belle II (2014~) http://www.kek.jp

8. 양성자-반양성자 충돌 가속기 실험(Tevatron) Heavier B => Full Service of B factory

9. 양성자-양성자 충돌 가속기 실험 (Large Hadron Collider) CERN LHCb ATLAS CMS ALICE LHC at CERN

10. High Energy Experiment

11. Fixed target vs Colliding beams (total energy)2-(total momentum)2 = invariant in all frames of reference Assume that 800GeV(Ebeam) proton collides in a fixed target(proton). Center of mom. frame Laboraroty frame Total energy: ECM Ebeam+mp2 Total momentum: 0 Pbeam Invariant: ECM2 (Ebeam+mp2)2-Pbeam2 E = [ 2(mp2+Ebeammp) ]1/2 = 38.8GeV We are enough to 19.4GeV+19.4GeV proton beams in collider !!! Question: What’s the advantage of a fixed target experiment?

12. In order to research about fundamental particles, physicists create collisions between high-energy particles After new particles have been produced in collisions, it is necessary to track and identify them. A particle detector is device (or system of device) used to monitor the process occurring in collision and to determine the particle created in collisions. Introduction to particle detector

13. To describe an event, one must/need to know: The time when the event occurred The direction of particles Momentum or Energy or Velocity of particles Identification of particles: Electric charge Mass Spin orientation Secondary decays within the detector volume. Identification of a particle

14. Interactions of particles and radiation with matter Ionization and track measurements Time measurement Particle identification Energy measurement Momentum measurement Particle Detectors, C.Grupen, Cambridge Univ. Press, 1996 Experimental techniques in HEP, T.Ferbel, World Scientific, 1991 http://www.cern.ch/Physics/ParticleDetector/BriefBook Goal of Particle Detector

15. Type of Detectors • Tracking Detector => momentum, charge • Particle ID => mass • Calorimeter => Energy • Muon Detector => Muon

16. 입자 검출기의 구성요소

17. Particle detector Muons (m) HAD Cal. Muon Cham. E.M. Cal. Tracker g Hadrons (h) e±, g e± m± Charged Tracks e±, m±, h± p±,p n Heavy material, Iron+active material High Z materials, e.g., lead tungstate crystals Heavy absorber,(e.g., Fe) Zone where n and m remain Lightweight

18. Principal types of particle detectors There are many particle detectors invented and developed. It is possible to divide them into two categories: • Tracking detectors: Monitor the trajectory of particle in collision • Cloud chambers • Emulsions • Bubble chambers • Wire chambers • Calorimeters (Shower detectors): Measure of particle’s energy, particle’s coordinates across calorimeter surface • Electromagnetic calorimeters • Hadronic calorimeters

19. Multipurpose detector : A variety of detectors 4 pi hermetic detectors Large cost and long time development and construction High end technology involved -> applied to industry (so many examples) High Energy Experiments Detector

20. Time when the event takes place: determined by a detector with fast response on passage of a particle (Scintillator and Photo-Multiplying tubes) Direction of particles: Charged particle: measure the ionization track left behind Neutral particle: measure center of gravity of a electromagnetic /hadronic shower Momentum of charge particle: from track curvature in magnetic field Energy of particle: from electromagnetic or hadron shower size Velocity of particle: from Time of Flight (TOF), Cerenkov light angle Energy-momentum: from the energy-momentum conservation laws Electric charge: from density of ionization (dE/dx) Mass of particle: from momentum vs velocity. Secondary decays within detector volume investigated by reconstructing an explicitly secondary vertex. How can detectors determine particles

21. Particles are detected via their interaction with matter Different physical processes For charged particles predominantly excitation and ionization The common methods for particle identification are: Vertexing and Tracking particles through a magnetic field. Thin (low Z) material Gas, liquid, solid Energy loss measurement Calorimeter High-Z material (absorber) ID of particles like Cerenkov Others like Time of flight High Energy Experiments Detector See http://public.web.cern.ch/public/

23. HEP detector

24. Structure of a typical particle detector Vertex detector: gives the most accurate information on the position of the tracks. Drift chamber: detects the positions and momentum of charged particle. Cerenkov detector: measures particle velocity Calorimeter, stops most of the particles and measures their energy. This is the first layer that records neutral particles The large magnet coil separates the calorimeter and the next layer.

25. Typical experimental setup

26. 1. Tracking Chamber

27. Heavy charged particle interactions w/ atoms

28. Tracking Particle through a Magnetic Field • Gas detectors: MWPC, TPC, Drift Chamber, GEM, … • Solid State (Silicon) detectors: PIN diode, CMOS, CCD, … (Pixel, Strip, ..)

29. Momenta of charged particles can be measured in a relatively straightforward fashion using magnetic spectrometer. In certain situations, however, magnetic measurement may not be viable. For example, precise magnetic measurements becomes difficult and expensive at very high energies because they require either large magnetic fields in extended regions of space, or very long lever arms for measuring small changes in the angular trajectories of particles passing through magnets, or both. In addition, magnets can not be used for measuring energies of neutral particles. Calorimeters are then used to measure the total energy deposition in a medium.

30. Tracking Detector: Cloud chambers • Invented by Charles Thomson Rees Wilson (Nobel Prize in 1927) • Used from the beginning of the 20th century till mid-1950s • Principle of operation: • In over-saturated vapor, primary ionization cluster left behind a charge particle. This particle will become center of condensation. Droplets will follow the track of particle. Their number per unit of length is proportional to the density of ionization. A picture of droplets is taken and chamber is compressed again. • Characteristics: • Moderate spatial resolution (mm to sub mm) • Momentum (P) calculated from curvature in magnetic field • Velocity (v) determined from dE/dx (density of ionization)

31. Wilson chamber (cloud chamber) Cloud-chamber photograph, showing track of positively charged particle (C. D. Anderson - 1932)

32. Tracking Detector: Emulsions • Used since mid-1940s and are still in use • Developed by F. Powell (Nobel Prize in 1950) • Principle of operation: • Emulsion films consist from crystal of AgBr and AgCl suspended in a body of gel. An charged particle passing through the emulsion film breaks up AgBr/AgCl molecules and releases metallic Ag grains. With the help of a microscope, these grains can be observed as black dots. • Characteristics: • Very high spatial resolution (0.2 m) • Momentum can be estimated from the scale of multiple scattering

33. Emulsion images A K meson stops at P, decaying into a muon and neutrals. The muon decays at Q to a electron and neutrals. The muon track is shown in two long sections.

34. Tracking Detector: Bubble chambers • Invented by Donald Glaser (from Berkeley, Nobel Prize in 1960) in 1952 and used from mid 1950s till the 1970s. • Principle of operation: • The bubble chamber consists of a tank of unstable transparent liquid. When a charged particle forces its way through the liquid, the energy deposited initiates boiling along the path, leaving a trail of tiny bubbles. Pictures from different angles are taken and the pressure is restored. • Characteristics: • Good spatial resolution (100 um) • Velocity determined from density of grains (dE/dx) • Momentum investigated from bending in magnetic field. • Quite appropriate for neutrino physics

35. Bubble chamber images The bubble chamber picture of the first omega-minus An incoming K- meson interacts with a proton in the liquid hydrogen of the bubble chamber and produces an -, a K° and a K+ meson which all decay into other particles. Neutral particles which produce no tracks in the chamber are shown by dashed lines. The presence and properties of the neutral particles are established by analysis of the tracks of their charged decay products and application of the laws of conservation of mass and energy. A 7-foot chamber at Brookhaven

36. Tracking Detector: Wire Chambers Here are some types of wire chamber: • Proportional counters • Multi-wire proportional chambers • Drift chamber

37. Tracking detector (-) (+)

38. Wire Chamber: Proportional Counters Principle of operation: A charged particle passing through a Geiger counter causes ionization. The ionization electrons drift to the wire creating further ionization, so producing a large signal.

39. Wire Chamber: Drift chambers - To achieve a high spatial solution over large area, an enormous number of wires is required --> high cost - A great reduction in cost can be achieved by using drift chambers (planar or cylindrical proportional chambers)

40. Drift chamber Some 35,000 fine wires are strung the length of the cylinder between precisely placed holes in the aluminum ends. When the chamber is filled with a gas mixture and high voltage is applied to groups of wires it becomes a giant set of Geiger counter The wires are arranged in layers that pass through the cylinder at three different angles. The set of wires that give a signal can be used to allow computer reconstruction of the paths of all the charged particles through the chamber

41. 2. Particle ID • dE/dx • TOF • Cerenkov detector

42. Particle Identification

43. 1) Energy Loss (dE/dx) • dE/dx Counter • A counter telescope consists of two or more detectors through which a charged particle passes in sequence, usually stopping in the last one. The fraction of energy dE it loses in the passing detectors is a measure of the stopping power. The stopping power (given by Bethe-Bloch formula to be discussed in a few weeks) varies approximately as z2/v2 or mz2/E, where v is the speed of the particle of mass m and charge ze. The energy E is obtained by summing the signals from all the detectors, and the product E x dE is roughly proportional to mz2. A graph of DE versus E gives a family of hyperbolae, each corresponding to a different values of mz2. For light ions with sufficient energy, this often is enough to identify the ion uniquely. However, this method is limited by the finite energy resolution of the passing detector.

44. Stopping power Heavy charged particles interact with matter mainly thru electrostatic forces during collisions with orbiting electrons. (excitation, ionization)

45. Global 5-parameter fit for phmp_nml vs • binning with nearly the same statistics at each point to reduce the error • Using garbage events in order to fastly calibrate this curve for BESIII in future • A uniform formula to avoid discrete expression for density effect • The curve fit the BESII data OK Beam-gas proton Radiative bb Cosmic rays BESII data p

47. 2) Time of Flight • Time of flight (TOF) measurements have important applications in providing discrimination between particles of similar momentum but different mass that may be produced from a reaction. For two particles of mass m1 and m2, the time difference will be given as: For p1 = p2 = p,

48. Time measurement The scintillation counter is capable of measuring a precise passing time of a particle because the scintillation is a fast phenomenum and the conversion of a light burst into a voltage signal inside PMT is also a very fast process.

49. 3) Cherenkov counter

50. Introduction: Gas Cherenkov Detectors Detection of Cherenkov light v > c/n in medium (refraction index n) β = c/v cosφ=1/nβ Reference: http://encyclopedia.thefreedictionary.com/Cherenkov%20effect HBD  Violet – Ultraviolet (VUV) light detection Georgia Karagiorgi, FAS 2005