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\title{On line analysis software requirements}
\author{Ph.Dessagne}
\date{Edition 1.0\\Octobre 1990}
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Projet EUROGAM\par
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On line analysis software requirements\par
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Edition 1.0\par
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octobre 1990\par
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Centre Recherches Nucleaires Strasbourg \par
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CNRS-IN2P3 France
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\bf {On line analysis software requirements.}
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  This note presents the preliminary reflexions on the on line event
 analysis of the french community involved in the EUROGAM project.
 It outlines the main requirements in that field and gives
 an indication on the conditions the event processor unit has to
 fulfill.    

\newpage
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\begin{center}
\bf {Description of typical analysis procedure during the experiments.}
\end{center}
  
  In the on line analysis we have to distinguish two main stages:
\begin{itemize}

\item The first one is relative to the creation of various one and two
 dimensional spectra. 
 It is essential to be able to built in direct mode and with conditions on 
 the ADCs (energy, time, fold, sum energy...) different distributions
 like germanium energy, time, multiplicity, sum energy,multiplicity versus 
 sum energy and gamma energy versus multiplicity. These informations
 have to be available for different exit channels selected either
 on criteria previously mentionned or by means of additionnal counters
 (recoil separator, particle detectors...). 
  Due to a high number of spectra it is necessary to have a clear interactive
 display of the various sorting conditions based on lookup tables. 
  First priority must be given to the constitution and the graphic 
 representation of direct and conditionned one dimensional spectra.
  The second priority would be the constitution and the display of 
 two-dimensional distributions on which we want to be able to define energy 
 gates in order to obtain the corresponding one dimensional spectra.

\item The second stage concerns the analysis of the conditionned spectra
 with programs and graphics tools used up to now at Daresbury 
 (cf. the note "userdoc" of Data analysis section 4. Ed.4.1 27/09/84)
 and Strasbourg.
\end{itemize}

\newpage
  It could be of interest to have during the experiment the possibility
 of analysis of high fold events.
 We have in mind that this sorting processes only after gain matching 
 for the Ge and selection by fold tresholds.
  Let us consider for example the case of five fold events. 
  To identify a nucleus or a reaction channel it is necessary to select at
 least two gamma rays in coincidence. The selection on the gamma energy
 has to be performed for each event on the five touched Ge counters.
  It could be useful to extend this procedure to four or five kind of nuclei
 produced in the reaction. For each identified product a two dimensional
 spectrum ( E(4K)* E(4K)) is then built up event by event from the
 informations delivered by the three others ADCs. If we want to define
 two set of conditions on each nucleus this leads to the creation of 8 or
 10 matrices (4K*4K) and a lookup table which contains the various sorting 
 gates.
  The next step is to project the resulting matrices on various axis and
 to store the corresponding one dimensional distributions in direct
 memory. Again graphic tools and analysis programms are essential.
  This treatement allows to check the threshold of the fold
 of the events taken into account by the event builder and yields 
 informations available immediately. 
  A more accurate evaluation of the data can be obtain with additionnal  
 programms allowing for example to substract the background in the
 constituted matrices. 
  These kinds of data reduction can be performed on the registered
 data (disk or tape) and nowadays it has presumabely to be considered as 
 a quasi on line analysis.

  In addition a selection of the Ge counter pattern may be of interest
 to the users.
  It is also necessary to have access permanentely to the rate of events
 analysed by the sorter. 
  For all the distributions (one or two dimensional) obtained during
 the measurement we require the possibility to store both on disk and tape.
  A fast hard copy of the screen is also needed.
 
  It is clear that the data processings on and off line are strongly correlated
 but in a first stage it is crucial to have access to a minimum of graphic
 tools to be able to perform a reliable software analysis in order to monitor 
 the quality of stored data.

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\bf {Ph. DESSAGNE}
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