Boris-san-seminar_slide.ppt.ppt

8.12.2008 Nagoya University experimental methods and detectors for present day particle physics B.Shwartz Budker Institute of Nuclear physics, Novosibirsk Introduction The development of particle detectors practically starts with the discovery of radioactivity by Henri Becquerel in the year 1896. He noticed that the radiation emanating from uranium salts could blacken photosensitive paper. Almost at the same time X rays, which originated from materials after the bombardment by energetic electrons, were discovered by Wilhelm Conrad R¨ontgen. The scope of the detection techniques in particle detectors is very wide, depending on the aim of the measurement. Each physics phenomenon can be used as the basis for a particle detector. Elementary particles have to be identified with various techniques, and relevant quantities like time, energy, spatial coordinates have to be measured. Particle physics requires extremely high accuracies for these quantities using multi-purpose installations as well as dedicated experimental set-ups. Historical remarks Main principles: ionisation - ~ 90%(?): charged – initial; neutral - secondary cherenkov transition radiation phonons (heat), Cooper pairs, etc. charged particles momentum mesurement Time progection chamber (TPC) TPCs have been operated often as the main tracker in a wide range of physics experiments: particle physics heavy ion collision underground experiments Vertex Detectors Strip Detectors Depleted p-n diodes Fast and efficient charge collection by drift in electric field 4 fC in 300 micron of Si (100 e-h pair per 1 mm of Si) Each strip has capacitance to backplane and neighbours Noise is typically dominated by serial contributions ? scales with detector capacitance Strips vs Pixels Strip detectors Large capacitance, 10 pF Large signal, 24000 e Large noise, 2000 e Well established area – dozens of small, large and huge trackers and vertex detectors in operation since ’90 New development: strips in depth of sensor –