Re: [Brahms-dev-l] comments to analysis (geometry)

Dear Flemming and Ian,

This analysis has started.
Calibration for DCs is supported by PS, geometry tuning by RP.
In the next step we plane to do tracking detector efficiencies in FS 
(PS) and
RICH efficiency (RK).

Cheers
Pawel.

PS. See also comment below.

flemming videbaek wrote:

> Hi Ian
> Thanks for the initiative to summarize the task to be done.
> I will like here to comment on a few specifics, that shows these first 
> taks will only be preliminary, and will have to be redone later and 
> better.
>  
> -geometry
> As always this is not an easy issue. Let me restate what I know
> -T5 has been taken in/out. It was resurveyed at least once; for the 
> first value the survey group was not happy- it was repeated but I have 
> not seen the numbers.
> T4,T4 was repositioned or rather levelled since there was known to be 
> a significant rotation in the XY plane (Pawel Oct 03).
> - T1 was moved significantly, and resurveyed. T2 is not knowned to 
> have been moved. If you dare to look at 0-field runs you will see a 
> significant difference in the T1-T2 matching even though the survey 
> was put into the DB (6-8 mm!!!!!)
> For each angle setting one CANNOT assume the t2-t3 alignement is good. 
> As I understand matching files and the way they are applied, this is 
> not sufficient for being able to use T2-t4 tracks for determining 
> momentum even though this is what has been done.
> So there are different issues here
> - some do need re-survey after the run (MAY 04)
> - other can be solved by doing DC geometry T3-T4-t5 w/o inclduing 
> t1,t2 that I do not trust well at this time
>  
> Actions:
> a) get Krakow group to optimize t3,t4,t5 geometry (after calibrations) 
> (PS)
> b) ensure survey is done after run.(fv/db)
> c) look at prelim T1 modifications (geom)9/fv)
> d) try to understand why (or why not) T1 tracks do point in Y to T2 
> and vertex after TPC has been calibrated.
>    (did anyone ever look at absolute fibre positions not just 
> differences ??) (who??)

Absolute position in Y can be also checked/used from track matching with T3.

>  
> /fv
>  
> ----------------------------------------------------------------
> Flemming Videbaek
> Physics Department
> Brookhaven National Laboratory
>  
> e-mail: videbaek@bnl.gov <mailto:videbaek@bnl.gov>
> phone: 631-344-4106
>
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