I think it is crucial to have this right before too much production gets done for several of reasons.
a) Spectra , and momenta matching cuts depends on this
b) some calibration in fact do also depend on this (unfortunately)
This is my reason for bringing this up and to get us to use a good set for the coming time.
I intend to spend some time in the next week on this, but to get going here is instalment no 1.
MRS:
As mentioned several times going back about 1.5 month we had come up with a default geometry. There are reasons it
was not complete optimal so the little table below gives value that real MUST be used- there are very small changes compared
to before and they are indicated
TPM1:
z 94.60 (unchanged) --- ~ouerdane/pid/12and90.geo 94.50
y 1.80 (unchanged) -0.2
x 0.00 (unchanged) -0.13
angle 90.0 90.0070
TPM2
z 286.60 (unchanged) 286.599
y 2.05 (unchanged) 0.93
x -0.20 (changed from 0 0.02
angle 89.66 (changed from 89.75)
This changes are not absolute. Having the angle change in TPM2 makes it consistent with the survey. Moving
the tpm2 in x by 2mm could probably also have been done for tpm1. The choice is consistent again with the survey.
a) The small change in angle and z improves the matching conditions (I will send plots in subsequent e-mail)
havind delta(x) delta(alx) and as a redult delat(amg)=0 for sero field runs. It was checked on run
b) the difference in the bend plane to the once used for the crs reco (ou/pid is quite small. That geometry guve too a very good
match in delta(alx) but has an offset of ~.4 cm in delat(x), and thus a worse delta(ang). Angain since the mom is determined by
alx (and not dang) is should only be very slightly affected.
c) lastly the geometry for the tof slats is identical in all cases.
I will like Kris if possible to update the the database defs for tpm1 and tpm2. I will update the geometry.dat files in brat
shortly.
Flemming
------------------------------------------------------
Flemming Videbaek
Physics Department
Brookhaven National Laboratory
tlf: 631-344-4106
fax 631-344-1334
e-mail: videbaek@bnl.gov
This archive was generated by hypermail 2b30 : Fri Dec 14 2001 - 13:19:11 EST