1. WHAT ARE THE SIGNAL IONS IN GAS DETECTORS ?
Yalçın Kalkan
Ionization Process in the Gas
ions are more abundant than
Avalanche
Charge exchange
Only ………………
clusters left !
Clustering
t=0 ns
t=1 ns
t=10 ns
Charge is transfer from to
Cluster formation by induced dipol

2. Conclusion : Signal ions are cluster ions in the gas detectors !
Mobility & Mass
Mobility decrease with mass.
Heavy molecules accept the elastic limit of Langevin.
Blanc’s Law
Ion Mobility in Mixture
Common assumption: …… is drifting in mixtures --> not true !
Proof : ALICE and NA49 data.
Conclusion : Signal ions are cluster ions in the gas detectors !
Reference : Yalcin Kalkan et al. (in press), “Cluster ions in gas-based detectors", JINST (June 2015).