In these pages a brief description of the detector is presented, with a collection of useful numbers, references and conventional names. The current reference, although slightly outdated in some details, is the Technical Design.
NA62 is a fixed target kaon experiment, on a dedicated beamline (K12), designed to be hermetic between 0 and 50 mrad in the forward direction, with an overall rejection capability of the order of 1012.
The picture below shows a schematic view of the layout (reversed with respect to the photo in the header), indicating the approximate position of most of the subdetectors along the almost 300m long beamline. The transverse size varies from O(10) cm up to 2 m in radius. There are two spectrometers: one upstream the decay region, for the beam particles, and the other, for the decay products; a set of different photon vetoes covers the whole angular acceptance, complemented by particle identification detectors for the beam and decay particles.
The NA62 reference frame is right-handed, with the Y axis pointing to the zenith and the Z axis on the direction of the beam upstream the first spectrometer; the beamline is roughly parallel to the Jura ans Saleve mountains, so the regions with X>0 and X<0 are often referred to as Jura and Saleve side respectively.
K12 beam line:
- SPS primary protons @ 400 GeV/c
- 75 GeV/c (Δ P/P ≈ 1%)
- Area @ beam tracker 16 cm2
- Divergence ≈ 100 μrad
- Kaon decays/year 4.8 × 1012
- Unseparated secondary charged beam
- p/π/K (positron free, K ≈ 6%, p ≈ 23%)
- Integrated average rate @ beam tracker 750 MHz
The beamline is the combination of two systems. The first, called P42, collects 400 GeV/c protons from the one of the primary targets (T4) of the SPS and delivers them, after about 900 m, onto the NA62 beryllium target (T10). From T10 an unseparated hadron beam is defined by the K12 beamline; the combination of a magnetic achromat, two TAXes and collimators define the momentum and shape of the beam. The beam elements are part of the standard SPS magnets kit.