Can Laser Primary Positive Ions Influence Electron Drift?

average charge along a min I path

guess at laser linear ionization density

Laser frequency

positive ion drift velocity in the z direction, this comes from Fig. 2.5, p. 63 in Blume and Rolandi. It is the positive ion drift velocity in P10 at 130 V/cm

sheet density of positive ions from a laser beam

Electric field from Gauss's law. Because of symmetry this is probably not a bad approximation for the radial laser beams.

maximum path length of drifting electrons

drift field in TPC

distortion integral

So this says no effect, but where might this be wrong?

We have assumed that the methane molecule carries the positive charge, this might be wrong particularly for the lasers. We don't know what contaminant is ionized by the laser, but we know that the laser can't ionize either the argon or the methane. The contaminant is probably a big heavy complex molecule. Once it is ionized by the laser, 2 photon process, it will probably remain as the positive ion. It was happier giving up an electron than any other molecule so it is unlikely that it will snatch an electron from any of it's neighbors. OK, maybe the positive ion is heavier than methane, factor of 10 or 100, but not 1000, unless we have mold growing in the TPC. I can't remember how drift velocity scales, is it 1/m or 1/sqrt(m).