Acceptance of ET44 for 1996.

V.Andreev, 20-May-1997

 The whole 1996 period of H1 running was split into  25 samples.
 For each sub-sample the acceptance of the ET44 was defined
 with the procedure described in H1 note #493.  The DB then was updated 
 with the new set of LET1 banks. A complete list of the bank versions
 is shown below:

 TransActID Rtyp Dtyp  1.Run   Words    Author      Date    

    1112139 e-p data  147095      46    vladimir  970422    
    1112140 e-p data  147893      54    vladimir  970422    
    1112141 e-p data  151573      54    vladimir  970422    
    1112142 e-p data  153565      54    vladimir  970422    
    1112143 e-p data  154375      54    vladimir  970422    
    1112144 e-p data  155369      54    vladimir  970422    
    1112145 e-p data  155869      54    vladimir  970422  
    1112146 e-p data  157870      54    vladimir  970422    
    1112147 e-p data  157908      62    vladimir  970422    
    1112148 e-p data  157954      54    vladimir  970422 
    1112149 e-p data  158087      62    vladimir  970422    
    1112150 e-p data  158371      62    vladimir  970422    
    1112151 e-p data  159110      62    vladimir  970422   
    1112152 e-p data  159917      62    vladimir  970422    
    1112153 e-p data  160680      62    vladimir  970422    
    1112154 e-p data  161154      62    vladimir  970422    
    1112155 e-p data  163250      62    vladimir  970422  
    1112156 e-p data  163834      62    vladimir  970422    
    1112157 e-p data  165103      62    vladimir  970422   
    1112158 e-p data  165680      62    vladimir  970422    
    1112159 e-p data  167407      62    vladimir  970422    
    1112160 e-p data  168036      62    vladimir  970422    
    1112161 e-p data  168954      62    vladimir  970422    
    1112162 e-p data  169740      62    vladimir  970422   
    1112163 e-p data  170250      62    vladimir  970422    

 It is necessary to remind that during 1996 the ET44 was operated
 in two different modes. Until the H1 run 157908 the ET44 was not
 moved and was situated at the distance ~3.1 cm from the electron
 beam ("Parking position"). After that, the operation procedure with 
 the ET44 was changed. When the stable Luminosity is declared by 
 HERA the ET44 is moved to the "Working position" at the distance 
 ~1.8 cm to the electron beam.

 The y-dependence of the ET44 acceptance for the different run
 periods are shown in the picture. You can compare it with the same  
 distribution for 1995. As it was recomended for 1995 data and
 also for the analysis 1996 data it is necessary to use the average 
 acceptance of the ET44 (integrated over some y-range). This y-range
 is slightly different for the different H1 runs. For the first part of
 the data taking when the ET44 was not moved the more suitable y-range
 is 0.04 < y < 0.22 and for the second part of 1996 this range must be
 increased up to 0.03 < y < 0.28. More exactly this y-range for the 
 certain run period can be obtained by using the ACET44(IRUN,Y,MODE) 
 function.

 The systematic error of the acceptance determination of the ET44
 is formed by three main parts:
   a) uncertainty in the energy scale determination -> 3 %,

   b) trigger efficiency  -> 1.5 %,
 
   c) error connected with the uncertainty in the position of the ET44
      with respect to the electron beam -> 5.5 %.

 So the overall systematic error of the acceptance determination
 of the ET44 in 1996 must be considered = 6.4 %.