By Archana SHARMA CERN Geneva Switzerland March 2009 Troisieme Cycle EPFL Lausanne, Switzerland

1. Gaseous Particle Detectors • By Archana SHARMA • CERN Geneva Switzerland • March 2009 • Troisieme Cycle • EPFL Lausanne, Switzerland

2. Archana.Sharma@cern.ch Who am I ? Education D.ScDoctorates Sciences particle physics: University of Geneva, Geneva, Switzerland, 1996 Ph.D. Nuclear Physics:  University of Delhi, Delhi, India 1983-89 M.Sc Master’s Science: Nuclear Physics, Benares Hindu University BHU, India 1980-1982 B.Sc Bachelor’s Science:  Benares Hindu University, India: Physics, Chemistry, Math. 1976 to 1980  ISCE Senior Cambridge: St. Francis’ Convent High School, Jhansi, India 1976 EMBA Executive Master in Business Administration: International University Geneva, Switzerland 2001 Employment: July 2001-present (Staff Physicist, CERN) 1999-2001 (Research Associate, University of Maryland,  USA, deputed to CERN) 1997-1999 (Foreign Research Scientist, GSI, Darmstadt; Germany, deputed to CERN) 1995–1996 (Associate Haute Université Mulhouse, deputed to CERN) 1992–1994 (INFN, Borsista de Studio, INFN Art 36, deputed to CERN) 1989–1992 (Detector Development Division, CERN) 1987- 1989 Student, Detector Development Division, and completion of Ph.D.

3. Chapter I 5th March 2009 • 1.1 Introduction • 1.2 Units and Definitions, Radiation Sources • 1.3 Interaction of Radiation with Matter • Chapter II 12th March 2009 • 2.1 General Characteristics of gas detectors, Electronics for HEP detectors • 2.2: Transport Properties • 2.3: Wire-based Detectors Tool

4. Chapter III 19th March 2009 3.1 Resistive Plate Chambers for Tracking 3.2 Aging and Long Term Operation 3.3 Micro-pattern Detectors Chapter IV 26th March 2009 4.1 Measurements of Energy, Momentum, Time of Flight 4.2 Designing a HEP Experiment 4.3 Applications Outside Particle Physics Tool

5. The World's biggest laboratory for particle physics research You are here FRANCE Who has not been to CERN ? Who has not heard of LHC ? SWITZERLAND

6. Every day, around 10 000 scientistsfrom all over the world perform research at CERN Truly International Methodology Flags of CERN’s Member States 20 European Member States and around 60 additional countries collaborate in our scientific projects.

7. Landmark of CERN The Globe of Science and Innovation The LHC is a discovery machine has the potential to change our view of the Universe, continuing a tradition of human curiosity that’s as old as mankind itself. The resulting innovation may have an unimaginable impact on our lives.

8. HIGH • ENERGY • PARTICLES • ACCELERATORS • INTERACTIONS • DETECTORS What is a TeV ?

9. The LHC is a proton proton collider 7 TeV + 7 TeV 1 TeV = 1 Tera electron volt = 1012 electron volt Rate 40 MHz The LHC will determine the Future course of High Energy Physics

10. What is a TeV ? An electron volt is a measure of energy.  An electron volt is the kinetic energy gained by an electron passing through a potential difference of one volt.  A volt is not a measure of energy.   An electron volt is a measure of energy.  An electron volt is very tiny. Suppose it takes a mosquito 30 seconds to travel a human body 165 cm and suppose its mass is 0.1 grams . . . What is its energy in TeV?

11. What is a TeV ? The Mosquito’s Kinetic Energy is E = ½ m v2 If it moves across 165 cms in 30 seconds Its velocity is 5.5 cm/sec So E=½ (0.1 gm)(5.5 cm/sec)2 = 1.51 ergs Convert ergs to eV by dividing by 1.602 x 10-12 E = 0.944 x 1012 eV or 0.944 TeV 1 joule is exactly 107 ergs 1 joule is approximately equal to: 6.2415 ×1018 eV (electronvolts)

12. Introduction • HEP experiments study the interactions of particles by observing collisions of particles • Result: change in direction / energy / momentum of original particles • And production of new particles

13. Detector elements p1 = -p2 1 2 p2 = 0 1 2 Experiments • These interactions are produced in • WHAT : measure as many as possible of the resulting particles from the interaction • HOW: put detector “around” the interaction point

14. Interaction of particles in detector components Fixed Target Collider 1 Tracking Detectors: Pixel, Silicon Strip, Gas Microstrip, Drift Cells, Tubes, Drift Chambers 2 Electromagnetic Calorimeters: Plastic Scintillator / Lead Sandwich, Liquid Argon, Crystals 3 Hadronic Calorimeters: Plastic Scintillator / Iron or Copper Sandwich, Liquid Argon 4 Muon Detectors: Drift - Tubes, Cathode Strip Chambers, Resistive Plate Chambers

15. See http://pdg.lbl.gov/atlas/index.html TOTALGaseous Detectors In ATLAS~ 10,000 m2 ATLAS

16. See http://cmsinfo.cern.ch/Welcome.html/ TOTALGaseous Detectors In CMS~ 10,000 m2

17. Just in case you wonder why? Knownparticles thatdisappeared after the Big Bang HighlyExpectedParticles Methodology E=mc2 Hypothetical Or totallyunsuspected ? SUSY

18. A Higgs Event in CMS Methodology 2 muons 2 electrons

20. Tools of the trade 1. Accelerators : powerful machines capable of accelerating particles up to extremely high energies and bringing them into collision with other particles. 2. Detectors : gigantic instruments recording the particles spraying out from the collisions. 3. Computers : collecting, stocking, distributing and analysing the enormous amounts of data produced by the detectors. 4. People : Only a collaboration of thousands of scientists, engineers, technicians and support staff can design, build and operate these amazing machines

21. SIZE OF THE DETECTORS

22. The ideal detector With an “ideal” detector, we can reconstruct the interaction, i.e. obtain all possible information on it. This is then compared to theoretical predictions and ultimately leads to a better understanding of the interaction and properties of particles For all particles produced, the “ideal detector” measures energy, momentum, type by : mass, charge, life time, spin, decays

23. Negative charge Magnetic field, pointing out of the plane Positive charge Measure and derive • The mass, velocity, energy and charge (sign) • from ‘tracking’ curvature in a magnetic field • The lifetimet • from flight path before decay t

24. Different type of particles to be detected • Charged particles • e-, e+, p (protons), p, K (mesons), m (muons) • Neutral particles • g (photons), n (neutrons), K0 (mesons), • n (neutrinos, very difficult) Different particle types interact differently with matter (detector) (for example, photons do not interact with a magnetic field) Need different types of detectors to measure different types of particles

25. e- p p p g e- p Principles of detection • Interaction of a particle with detector Sensitive Material Measureable Signal • Ionization • Excitation • Particle trajectory is changed due to • Bending in a magnetic field, energy loss • Scattering, change of direction, absorption

26. Ionization signals by using • Gaseous detectors: • MWPC and its derivatives • (Multi-Wire Proportional Chambers) • Drift Chambers (DCs) • TPC (Time Projection Chamber)

27. Key Points: Lecture 1-1 • Requirements for response from (gaseous) detectors • Fast • Light • Hermetic • Radiation Tolerant

28. Exercise: Lecture 1-1 • Make a list of five - light yet strong materials that can be used as mechanical support and can withstand high radiation: • Insulators • Conductors • Sheets

29. Chapter I 5th March 2009 • 1.1 Introduction • 1.2 Units and Definitions, Radiation Sources • 1.3 Interaction of Radiation with Matter • Chapter II 12th March 2009 • 2.1 General Characteristics of gas detectors, Electronics for HEP detectors • 2.2: Transport Properties • 2.3: Wire-based Detectors Tool