Minutes of meeting on trigger symmetrisation and normalisation
held on 28/9/1994
Present:
M.Dejardin, C.Touramanis, T.Ruf, M.Chertok

M.Chertok presented a study of the PID (S1,Ce) performance in different 
magnetic field. He used 2*2 T1 tapes taken before and after a change
of the magnetic field. The peak values and gains found for M1 and M2
are in good agreement. He also checked the PID performance using the LEDs 
and found the same result.
The large asymmetries in the DEDXS1 values found by A.Schopper 
may be explained by the fact that for a sharp falling or raising
distribution any small shift between the two distribution to compare results 
in a large asymmetry or ratio.  
We don't expect positive and negative pions to give exactly the same
energy loss in the scintillator. Secondly comparing the same particle
in a different magnetic field has always the problem that the data 
were not taken at the same time and therefore the S1 response might be
a bit different.

T.Ruf presented some normalisation results using C.Touramanis data
integrating over all kinematic variables in an early lifetime region.
The ratio of recorded events in M1 and M2 is the same
for the three event classes:
2prim:         1.0451        3prim:    1.0442        4prim:   1.0460         
             +/-.37056E-02             +/-.17872E-02         +/-.68079E-03    
The normalisation (K0=/K0) in M1M2 and M2M1 agrees very well after
correcting for the M1 M2 flux ratio:

2prim    M1M2           M2M1
         1.1391         1.1341    
     +/-.57974E-02  +/-.56268E-02
3prim
         1.1361         1.1359    
     +/-.27774E-02  +/-.27335E-02
4prim
         1.1373         1.1334    
     +/-.10568E-02  +/-.10377E-02

and more over the normalisation seems to be the same for the three
different event classes.
The difference of 2prim events and 4prim events appears by applying the
4prim LUT to the 2prim:

 2prim
       1.0108         1.0178    
  +/-.53493E-02  +/-.51276E-02
 3prim
      1.0067         1.0062    
  +/-.25602E-02  +/-.24669E-02
 4prim
      1.0029         1.0027    
  +/-.97073E-03  +/-.93562E-03

C.Touramanis tried 4 different ways to obtain phi+-:
Using no LUT and one normalisation factor:  
                  phi+- = 39^o
Using 4prim LUT:  
                  phi+- = 39.9^o
Using 3 diff. normalisation factors for 2prim 3prim 4prim events: 
                  phi+- = 39.1^o
Using 4prim LUT and 3 diff. normalisation factors for 2prim 3prim 4prim events: 
                  phi+- = 42.6^o
For the moment it is unclear why two different methods each used individually
gives almost no difference, but applying both shifts phi+- by 3.6^o.

Frederic Blanc will take care about the reprocessing of MC and 92 data.

The next meeting will be held on next wednesday 10am in the CPLEAR 
conference room.

Thomas