Single-hit resolution measurement with MEG II drift chamber prototypes

Understand

Drift chambers operated with helium-based gas mixtures represent a common solution for tracking charged particles keeping the material budget in the sensitive volume to a minimum.

• The drawback of this solution is the worsening of the spatial resolution due to primary ionisation fluctuations, which is a limiting factor for high granularity drift chambers like the MEG II tracker.
• We report on the measurements performed on three different prototypes of the MEG II drift chamber aimed at determining the achievable single-hit resolution.
• The prototypes were operated with helium/isobutane gas mixtures and exposed to cosmic rays, electron beams and radioactive sources.