Ring Separated and Event Selected Data Files

Many INDRA analysis tasks require only data of a single ring or of two adjacent rings which share a Chio. Data files which contain only information of such a ring subset will store more events per unit of storage volume and thus allow in many cases a faster analysis. We so far have created 11+1 extractions:
        r01             Ring select:    R  1
        r02_r03         Ring select:    R  2/ 3
        r04_r05         Ring select:    R  4/ 5
        r06_r07         Ring select:    R  6/ 7
        r08_r09         Ring select:    R  8/ 9
        r10_r11         Ring select:    R 10/11
        r12             Ring select:    R 12
        r13             Ring select:    R 13
        r14_r15         Ring select:    R 14/15
        r16_r17         Ring select:    R 16/17
        etalon          Module select:  Etalons
        etaevt          Event select:   Etalons
The basic logic of the production program is very simple and based on two `masks' per extraction, the `RequiredMask' and the `CopyMask'. A mask is nothing but a list of labels, entered into the program via a list of parameter names.

The program does for each event and extraction

  1. a check whether there is any parameter in the RequiredMask
  2. if this was successfull copies all parameters in the CopyMask into the associated output stream

Ring/Module selections

Most of the files are ring or module selections. In this case subsets of the events are generated, holding the hits of a particular ring or module selection. In these cases: Some other features worth mentioning are:
  1. The JBUS buffers are passed. This allows to use them as a time marker.
  2. The SCALER buffers are currently not passed.
  3. Two new parameters are defined and properly declared in the PARAM buffers:
            MULT_SI
            MULT_CSI
    	MULT_HIT
    
    MULT_SI and MULT_CSI contain the Si and CsI multiplicity of the original event, repectively. The multiplicity is determined by counting the number of complete (PG,GG,T) or (R,L,T) triplets, so single time markers or ADC's without a time marker are not counted.
    MULT_HIT is calculated as the number of modules with some analog information for a Si, Si75, SiLi or CsI. Note, that the Chio's and the time marker are not included in this algorithm. MULT_HIT should be a good estimate for the number of particles, while MULT_SI and MULT_CSI can be used to distinguish pulser, laser and physics events in runs where PATTERN is unavailable.
  4. The PARAM buffers contain by popular demand the description of all parameters, and not just those available in the particular extract.
  5. All bad events with a (-1,-1) label/value pair are discarted.
  6. The overflows are handled slightly differently compared to the original raw data ! In the original files an ADC overflow produces a value of 4095 AND a label with the sign bit set (so you'll see in effect a negative label).
    In the `ring separated' files the sign bit of the label is not set in case of an overflow, the only signature of an overflow is a value of 4095.

Event selections

The etaevt selection is in contrast to the other cases an event selection. In this case the complete raw data event is copied if a condition is fullfilled. As a consequence, the CopyMask is simply a list of all available parameters. There are currently the following selections:
etaevt: Events with an Etalon module
The aim is to study the etalons under global event cuts beyond what is possible with the stored multiplicities like MULT_SI on the etalon extraction. A prestudy showed the following relative size of the output file for a typ. run (4625):

Selection Size
every event where a Si75, SiLi or CsI ADC fired 48.2%
as above, but pulser and laser events excluded 26.3%
every event where a Si75 or SiLi time marker fired 13.1%
as above, but pulser and laser events excluded 5.4%

A selection based on the time markers selects only the events where an etalon was really hit while a selection based on the presence of the analog signal essentially selects all events where the module was hit. Because of the much better selectivity the time marker selection was used.

Configuration files

The configuration files (look for cmask*.conf and rmask*.conf) are accessible under
http://www-kp3.gsi.de/dat/cvs/s185/conf/
See also the summary of the configuration settings which gives in a quite readable tabular fashion a compressed representation of the configuration files.

A list of available tapes with ring separated data is given elsewhere.

See also the description of IDH_rawmultiselect.

Back to INDRA Raw Data


Walter F.J. Mueller
Last modified: Thu Mar 2 16:58:48 CET 2000