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

Straw Tracker

The purpose of the Straw Tracker is to measure with good accuracy the direction and the  momentum of secondary charged particles originating from the decay region

straw

CAD model of one station inserted in the vacuum tank

  • 4 stations
  • 4 "views" in each station
  • Each view has 448 (4x112) straws in each view
  • -> 448x4x4 = 7168 straws
  • Operate in vacuum at 1x10 -6 mbar
  • 2.1m long with Di=9.8mm
  • Mechanically independent straw
  • Pretension in straws of 1.5 kg and two intermediate spacers for positioning. This is mandatory for the horizontal straws (x) and the straws at 45 degrees (u,v)
  • Precise tracking (<120 Ám)
  • Hermetic for tracks -3° < O < 3°
  • Particle rate in the straw: up to 0.5 MHz
  • Non-flammable gas mixture CO2 (90%)+ CF4 (5%) + Isobutene (5%)

straw layout

Section of straw layout in one view