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Small Sample Rare Eta MC




Hi Liping and Ashot,

First of all, we may want to eventually keep traffic off of this halld- 
physics list.  I imagine that once we start exchanging files there are  
going to be lots of technical questions.  I'll send this first note to  
the whole list but maybe subsequent discussion should happen directly.

I put a sample root file here:

http://dustbunny.physics.indiana.edu/~mashephe/primex/

Which comes from a subset of Lipings rare eta events.

The file contains one tree called "event"  (The dump of the fields is  
pasted below.) and a simple histogram of the total invariant mass of  
all photons in the calorimeter.

The event tree is mainly two sets of arrays.  One is indexed on n and  
contains the reconstructed four vectors of the n photons found in the  
detector.  The other indexed on nGen contains the generated four  
vectors and type of the nGen generated pi^0, etas, or photons.  These  
generated types correspond just to those you supplied in the ascii  
file and does not consider decays for example of pi^0 -> gamma gamma.   
So each of Liping's events will have 3 generated particles:  2 photons  
and a pi^0.  Each of Ashot's will have 2 particles, just the two  
photons.  (I do not record generator info for other particle types  
since it isn't of use for us at the moment.)

Then genNeuE contains the total energy of all neutral particles and  
electrons and positrons.  When generating the background I plan to  
preselect events by placing a loose cut on this variable.  This way I  
do not spend huge CPU time to generate events that we will certainly  
toss out.  This is important to be able to get enough statistics to  
get some feel for the background.  As long as this cut is loose enough  
then I don't have to worry about this cut artificially reducing the  
background.  A similar variable, neuETot, is the sum of all the  
reconstructed neutral energy (a good first variable to cut on in an  
analysis).

I have not included raw hit information.  This would increase file  
size dramatically.  It could easily be done, but after our phone  
conversation today I'm not sure if you have plans to use it right away.

-Matt


******************************************************************************
*Tree    :event     : Event  
Reconstruction                                   *
*Entries :    10000 : Total =         1882594 bytes  File  Size =     
1363534 *
*        :          : Tree compression factor =    
1.37                       *
******************************************************************************
*Br    0 :n         : n/ 
I                                                    *
*Entries :    10000 : Total  Size=      40677 bytes  File Size   
=       4586 *
*Baskets :        1 : Basket Size=      32000 bytes  Compression=    
6.98     *
*............................................................................*
*Br    1 :E         : E[n]/ 
F                                                 *
*Entries :    10000 : Total  Size=     228491 bytes  File Size  =      
183329 *
*Baskets :        8 : Basket Size=      32000 bytes  Compression=    
1.19     *
*............................................................................*
*Br    2 :px        : px[n]/ 
F                                                *
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187776 *
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1.16     *
*............................................................................*
*Br    3 :py        : py[n]/ 
F                                                *
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187842 *
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1.16     *
*............................................................................*
*Br    4 :pz        : pz[n]/ 
F                                                *
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184061 *
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1.18     *
*............................................................................*
*Br    5 :neuETot   : neuETot/ 
F                                              *
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26283 *
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1.22     *
*............................................................................*
*Br    6 :nGen      : nGen/ 
I                                                 *
*Entries :    10000 : Total  Size=      40698 bytes  File Size   
=        263 *
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121.66     *
*............................................................................*
*Br    7 :genE      : genE[nGen]/ 
F                                           *
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118567 *
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1.30     *
*............................................................................*
*Br    8 :genPx     : genPx[nGen]/ 
F                                          *
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122566 *
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1.25     *
*............................................................................*
*Br    9 :genPy     : genPy[nGen]/ 
F                                          *
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122616 *
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1.25     *
*............................................................................*
*Br   10 :genPz     : genPz[nGen]/ 
F                                          *
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118466 *
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1.30     *
*............................................................................*
*Br   11 :type      : type[nGen]/ 
I                                           *
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14124 *
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10.88     *
*............................................................................*
*Br   12 :genNeuE   : genNeuE/ 
F                                              *
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20990 *
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1.52     *
*............................................................................*