Gap between paderow used for seeding as parameter in AliTPCRecoParam

Gap between paderow used for seeding as parameter in AliTPCRecoParam

(Marian)

Some theoretical consideration:

The track seeding efficiency depends on the cluster finder efficiency - ceff.
ceff is dEdx dependent, in mean is about 0.8 for MIP is about 0.75
The probability to find a seed=
pseed = ceff^3
Probability to find a track in nseedings
ptrack = (1-(1-pseed)^nseeding)

nseedin = npadrows/gap.
Until now we were seeding in outer sectors with gap 6 and 10 pad-rows (r dependent).

For tracks crossing the full TPC the track finding efficiency is
( you can draw it using TF1 f1("f1","(1-(1-0.75**3)**((160.-64.)/x))",1,10))
99.5% once the gap 10 pad rows is used.

For short tracks = kink decays e.g 30 cm from the end of TPC it is about 65% for gap 10 pad-rows, 85% for 5 gap 5 and 95% for gap 3 pad-rows.
(see function
TF1 f1("f1","(1-(1-0.75**3)**((20.)/x))",1,10))