Speakers
Mr
Mesut Arslandok
(Goethe University)Mr
Yalçın Kalkan
(Uludağ University, Bursa)
Description
Avalanches in gas-based detectors using
$\mathrm{Ar}\mbox{-}\mathrm{CO}_2$ or
$\mathrm{Ne}\mbox{-}\mathrm{CO}_2$ as drift medium
produce in a first instance $\mathrm{Ar}^+$, $\mathrm{Ne}^+$ and $\mathrm{CO}_2^+$ ions.
Although there is a wealth of information in the literature about ion transport and ion chemistry,
some gas-detector simulations simplify the treatment of ions to excess,
e.g. by taking only the noble gas ions into account,
neglecting the role of the quencher.
The noble gas ions transfer their charge to $\mathrm{CO}_2$ in a few ns.
Over the next few ns the $\mathrm{CO}_2^+$ ions pick up $\mathrm{CO}_2$ molecules
and thus cluster ions, in particular $\mathrm{CO}_2^+\cdot(\mathrm{CO}_2)_n$ are formed.
Since the cluster ions are $\sim 20~\%$ slower than the initial ions, the
ion-induced signals are substantially altered.
The effect is shown to be present in constant-field detectors
(LIP-Coimbra) and TPC readout chambers (ALICE and NA49), and is expected to affect devices such as Micromegas and
drift tubes.
Primary authors
Mr
Mesut Arslandok
(Goethe University)
Mr
Yalçın Kalkan
(Uludağ University, Bursa)
