Search

The NA62 experiment at CERN is intended to measure, with 10% relative error, the Branching Ratio of the K decay $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ which is expected to occur only in about 8 out $10^{11}$ kaon decays. The measurement strategy is to detect the decaying kaon and its product $\pi^{+}$ and to reject all the background channels, which are up to ten orders of magnitude more abundant than the signal, using both kinematical constraints and particle identification systems as veto. The exceptionally low signal yield makes it necessary to prevent also background which is not due to kaon decays, but is rather connected to the interaction of the intense hadron beam with the residual material enconuntered along the decay volume including the beam spectrometer itself: in order to reduce to an acceptable level this last background we designed the Charged Anti Counter (CHANTI). CHANTI is designed to be a compact, efficient and fast response detector to be operated in vacuum and is made up assembling FNAL-NICADD scintillator bars and fast wavelength shifter fibers. It is read out via silicon photomultipliers coupled to fast electronics. It is composed by 6 stations with x-y views and tracking capability; we already constructed 90% of the bars needed, and we characterized more than 50% of them. Finally, the first station was fully assembled and it was tested in the NA62 framework during a testbeam in November 2012. The data collected allowed us to estimate the time resolution of the station, which is a crucial parameter of every veto system. A first MonteCarlo estimation of the amount of the potentially dangerous inelastic interactions was performed showing that it could be a primary source of background, also taking into account the rejection factor ensured by the CHANTI and the other detectors. It is thus indispensable to plan a strategy towards a data-driven estimation of this backgrund source.

The NA62 experiment at CERN is intended to measure, with 10% relative error, the Branching Ratio of the K decay $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ which is expected to occur only in about 8 out $10^{11}$ kaon decays. The measurement strategy is to detect the decaying kaon and its product $\pi^{+}$ and to reject all the background channels, which are up to ten orders of magnitude more abundant than the signal, using both kinematical constraints and particle identification systems as veto. The exceptionally low signal yield makes it necessary to prevent also background which is not due to kaon decays, but is rather connected to the interaction of the intense hadron beam with the residual material enconuntered along the decay volume including the beam spectrometer itself: in order to reduce to an acceptable level this last background we designed the Charged Anti Counter (CHANTI). CHANTI is designed to be a compact, efficient and fast response detector to be operated in vacuum and is made up assembling FNAL-NICADD scintillator bars and fast wavelength shifter fibers. It is read out via silicon photomultipliers coupled to fast electronics. It is composed by 6 stations with x-y views and tracking capability; we already constructed 90% of the bars needed, and we characterized more than 50% of them. Finally, the first station was fully assembled and it was tested in the NA62 framework during a testbeam in November 2012. The data collected allowed us to estimate the time resolution of the station, which is a crucial parameter of every veto system. A first MonteCarlo estimation of the amount of the potentially dangerous inelastic interactions was performed showing that it could be a primary source of background, also taking into account the rejection factor ensured by the CHANTI and the other detectors. It is thus indispensable to plan a strategy towards a data-driven estimation of this backgrund source.