CERN - European Organization for Nuclear Research - Physics Department - NA62


The muon veto system (MUV) consists out of three distinct parts, called MUV1, MUV2, and MUV3.

The first two modules (MUV1 and MUV2) follow directly the LKr calorimeter and work as hadronic calorimeters for measurement of deposited energies and shower shapes of incident particles. While MUV2 is the front module of the former NA48 hadron calorimeter (HAC), but turned by 180, the MUV1 module is a newly constructed detector. Both modules are classic iron-scintillator sandwich calorimeters with 24 (MUV1) and 22 (MUV2) layers of scintillator strips. In both modules, the scintillator strips are oriented alternating in horizontal and vertical direction. In the MUV1 module light is collected by wave-length shifting (WLS) fibers, while the MUV2 module routes the scintillating light by light guides directly to photomultiplier tubes.



  • 25 iron, 12 vertical & 12 horizontal scintillator layers, 260 260 cm 2 each
  • Scintillator length 260 cm; width: 4 cm or 6 cm, thickness 10mm + 3mm gap
  • Iron layer thickness: 25 mm (as in existing HAC) => 625 mm iron


  • Former NA48 HAC front-module, turned by 180°, serves as veto only.


  • Two layers (x,y) of new fast MUV after 80 cm of iron wall.