1 FK7003 Lecture 17 Interactions in Matter Electromagnetic interactions in material Hadronic interactions in material Electromagnetic and hadronic showers 2 FK7003 Why we can neglect weak interactions E (TeV) Neutrino interaction lengthi In water/km Probability of interaction ~ / km water at 100 TeV energy 100 billion neutrinos pass through your thumbnail each second but only 1-2 will interact in your body during your lifetime. From lecture 3 Mean distance between interactions of neutrino + water molecule as neutrinos pass through water (interaction length). 3 FK7003 Strategy Energy loss of particles in matter Electromagnetic energy loss Energy loss through collisions (ionisation) Radiation loss Electromagnetic shower Hadronic energy loss Energy loss through nuclear collisions Hadronic shower 4 FK7003 Ionisation energy loss M 5 FK7003 M l Semi-classical derivation (skip) 6 FK7003 7 M 8 9 10 FK7003 Interaction between two particles 11 FK7003 Bethe-Bloch formula (17.23) 12 FK7003 Bethe-Bloch formula 13 FK7003 Measurements of ionisation energy loss e 14 FK7003 Strategy Energy loss of particles in matter Electromagnetic energy loss Energy loss through collisions (ionisation) Radiation loss Electromagnetic shower Hadronic energy loss Energy loss through nuclear collisions Hadronic shower 15 FK7003 Radiation energy loss E0E0 x 16 FK7003 Energy loss of an electron in copper ECEC 17 FK7003 Question 18 FK7003 Strategy Energy loss of particles in matter Electromagnetic energy loss Energy loss through collisions (ionisation) Radiation loss Electromagnetic shower Hadronic energy loss Energy loss through nuclear collisions Hadronic shower 19 FK7003 Photons 20 FK7003 Photon absorption in lead Lead 21 FK 22 FK (i) (ii) 23 FK7003 Electromagnetic shower E0E0 E 0 /2 E 0 /4 t=No. X 0 No. e + No. e - No. No. particles 24 FK7003 Electromagnetic shower Observed electromagnetic shower (next lecture) 25 FK7003 Strategy Energy loss of particles in matter Electromagnetic energy loss Energy loss through collisions (ionisation) Radiation loss Electromagnetic shower Hadronic energy loss Energy loss through nuclear collisions Hadronic shower 26 FK7003 Hadronic energy loss p xx 27 FK7003 Nuclear shower EM Cascade Nuclear cascade 28 FK7003 A simple model for hadronic scattering in material p p L xx 29 FK7003 p L Interaction Length xx 1 23 p 30 FK7003 Proton-nucleon cross sections p p 31 FK7003 Nuclear interaction length 32 FK7003 Stopping in iron 33 FK7003 Strategy Energy loss of particles in matter Electromagnetic energy loss Energy loss through collisions (ionisation) Radiation loss Electromagnetic shower Hadronic energy loss Energy loss through nuclear collisions Hadronic shower 34 FK7003 Energy loss mechanisms Important energy loss mechanisms for collider experiments (next lecture). ParticleIonisation energy loss Radiation energy loss Hadronic energy loss e + e - pair production e-e- Important only for low energies (several hundred GeV ) xx Charged hadrons (p, K ) Important only at high energies (E > several hundred GeV: K - ; E> 1 TeV: p ) x Neutral hadrons (n,K 0 ) xx x Photon xxx Not important for these lectures 35 FK7003 Summary Interactions of particle in material Electromagnetic and hadronic energy loss Ionisation and radiation energy loss (em) Hadronic energy loss (strong) Now ready to design an detector for a collider experiment (next lecture).