Speaker
Karim Massri
(University of Birmingham (GB))
Description
The NA62 Experiment aims to measure the branching ratio of the ultra-rare kaon decay $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ with 10\% precision, collecting $\sim 100$ events in 2 years of data taking, starting in 2014. Assuming the value of the branching ratio as predicted by the SM ($BR(K^+ \rightarrow \pi^+ \nu \bar{\nu}) = (8.5\pm 0.7) \times 10^{-11}$), to collect enough statistics a high-intensity kaon beam is needed. Besides the $K^+ \rightarrow \pi^+ \nu \bar{\nu}$ decay, many other rare or forbidden kaon decays can be studied, given the required kaon flux ($\sim 10^{13}$). The highest intensity hadron beam available at CERN is a 800~MHz unseparated secondary beam, in which the kaon component is only the 6\% (50~MHz average). This results in a $\sim 10$~MHz rate in the sub-detectors after the 65~m long decay region.
In principle, the most flexible and unbiased way to readout sub-detector data would be using a ``triggerless'' acquisition system, in which all the data are unconditionally transferred to PCs. However, the NA62 high rate and channel count ($\sim 100000$) make this choice infeasible. Therefore, a variety of hardware lowest-level (L0) triggers will be used to reduce the overall rate below $\sim 1$~MHz but preserving most of the decays of interest.
Following a L0 trigger, most sub-detectors will transfer data to dedicated PCs, where two trigger levels (L1 and L2) will be applied via software, to reach a final rate of $\sim 10$~kHz.
In this talk the NA62 triggers and the relative rare decays selection algorithms will be described
Primary author
Karim Massri
(University of Birmingham (GB))
