Relatore
Dr.
John R Fry
(University of Liverpool)
Descrizione
The CERN experiment NA62 is dedicated to the study of ultra-rare decays of the K+ in the pursuit of physics effects beyond the standard model (SM). The flagship decay K+ → π+νν has a branching fraction (BF) predicted by the SM to be (7.81 ± 0.75 ± 0.29 )×10-11and the collaboration will identify more than 100 such decays during data-taking in 2015-17 to enable a measurement of the BF to better than 10%. The necessary high number of K+ decays is obtained by exploiting an unseparated monochromatic (75 GeV/c) beam of charged particles of flux 800 MHz, of which 50 MHz are K+. Kaons are identified with more than 95% efficiency, a time resolution of better than 100 ps, and misidentification of less than 10-4 using KTAG, a differential Cherenkov detector that makes use of the gas volume and optics of a CERN CEDAR counter. KTAG utilises 8 sets of 48 Hamamatsu PMTs, of which 32 (16) are of type 9880 (7400), with signals fed directly to the differential inputs of NINO front-end boards and thence to TDC boards within the TEL62 system. Leading and trailing edges of the discriminated signal are digitised, enabling slewing corrections to be made, and a mean hit rate of 5 MHz per PMT is supported. The electronics is housed within a cooled and insulated Faraday cage with environmental monitoring capabilities. During a pilot run in autumn 2014 KTAG met its design specification.
Autore principale
Sig.na
Angela Romano
(University of Birmingham)
