[Hps-ecal] few questions about ECal alignment

[Stepan Stepanyan]

Dear all,

There was a discussion at yesterday's software meeting about the ECal 
positioning.
I want to ask if some of you can do quick studies of some issues to 
clarify few things.
It might be that these questions have been already answered and someone 
knows the
answers, or someone is in process of getting this resolved, so please 
share whatever
you have with the group. Here are the questions:
1) what is the track extrapolated position resolution at the ECal?
Basically I want to have have few thousands E=0.5 GeV e+ and e- be 
simulated in groups
of fixed angles, phi and theta, and for each group distribution of X and 
Y positions
at the calorimeter been studied. The field map can be anything, as long 
as it has stray
field distribution

2) what is the effect of the ECal Y-position on the trigger performance?
This simply can be the same studies Kyle does with the trigger, but with 
different
Y-positions of the ECal. Kyle already has one fixed position studied, if 
he can do
the same by moving top ECal by 1 mm, 2mm, 3mm ... and see how trigger 
efficiency
to A's changes, then move both the same way. I want to understand how 
much ECal
should be misaligned to effect our trigger.

3) what is the effect of the Y-alignment on the ECal energy resolution?
Here the worry is that when we do sampling fraction corrections, that 
corrections
depend on the position of the hit. Closer to the edges, e.g. in row 1, 
larger the
corrections. Of course closer to the edges worse resolution we will 
have. Now one
can derive sampling fraction correction as a function of hit position in 
row 1 using
some geometry (nominal will work), then correct cluster energy by 
applying sampling
fraction correction not for the position that cluster reconstruction 
algorithm is giving
but shift it by 1 mm, 2mm , 3 mm ..., and look to see what is the energy 
resolution and
compare to the nominal one.

Please let me know if anyone can take any of these tasks and if there 
are questions
on what is above.

Thanks, Stepan