Aerogel RICH for the Belle II forward PID

Development of a 144-channel Hybrid Avalanche Photo-Detector for Belle II ring-imaging Cherenkov counter with an aerogel radiator

“…The prototype Aerogel RICH consists of an aerogel radiator and six HAPDs, configured as they would be in the real counter. In the test, one of the HAPDs is replaced to a sample which was irradiated to neutrons and gamma in advance, but we do not see any significant difference in the performance of the Aerogel RICH [10].…”

The Aerogel RICH detector of the Belle II experiment

“…In addition, the background level in this decay mode can be effectively reduced by requiring the difference of reconstructed invariant masses of D * and D 0 mesons to be within a narrow window around the expected value (|M D * − M D 0 − 145.43 MeV/c 2 | < 1.5 MeV/c 2 is used). We determine the efficiency of kaon identification 2 and pion misidentification rate 3 from the signal yield of reconstructed D 0 's, where pion or kaon track used in the reconstruction is required to satisfy the imposed selection criteria on PID likelihood ratio obtained from the ARICH (R with pion (kaon) track entering ARICH. Fainted points and lines show the case when no selection is imposed on R[K/π] and solid points and lines after imposing R[K/π] > 0.6.…”

“…In addition, excellent lepton identification is required for measurements of possible lepton flavor violating decays and tests of lepton flavor universality. At Belle II PID is provided by the time-ofpropagation counter (TOP) in the barrel and aerogel RICH counter (ARICH) in the end-cap region [2]. The goal of the ARICH is mainly to provide very good π/K separation in the full kinematic range of the experiment (4σ separation at momenta between 0.5 and 3.5 GeV/c), and to provide discrimination between π, µ and e below 1 GeV/c (relevant for rare decays, such as B → Kll).…”

The Super C-τ Factory particle identification system options

“…In this way it is possible to increase the number of photoelectrons by increasing the radiator thickness without degradation of the Cherenkov angle resolution for single photons. It is possible to provide focusing effect by using a stack of several aerogel blocks as in the Belle II ARICH system [9] or produce a monolithic multiple layer block. The second approach was considered for the FARICH endcap system of the Super B factory (LNF, Italy) [10] and the SCT project [11].…”