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Hello ECAL folks,

I am mightily confused about our Ecal collections in LCIO. Without reading a ton of code, could someone please help me sort some things out here?

According to the Confluence page:

EcalClustersCorrClusterCopyClusterCollectionDriver
reconstructed ECal clusters with corrected energies

This is very confusing. The driver “CopyClusterCollectionDriver” is supposed to just copy a collection, not also make corrections to the timing and energy, and indeed, it doesn’t seem to, so then EcalClustersCorr and EcalClusters are identical, or not? If they are the same, why? If not the same, how?

I just confirmed that the hits that written in the “EcalClustersCorr” collection are NOT the same as those in EcalCalHits, when these hits have the same ID. So that puzzles me. Where are those hits changed? What collection are the corrected hits in?

The “ReconClusterer” (nicely commented and quite readable code, thank you) that made the EcalClusters collection uses the EcalCalHits and does not appear to make any corrections to them. Am I wrong?

Any help here would be appreciated. We can update the Confluence page with the answers.

Best,
Maurik


On Sep 20, 2016, at 2:54 PM, Maurik Holtrop <[log in to unmask]> wrote:

Hello Omar and Sebouh,

I will look into the issue of the hits timing, and directly compare the various collections we have in LCIO. Give me a little time though.

In the LCIO files, I can find the EcalReadoutHit (sounds like it is “raw” hit from Ecal) and hte EcalCalHit. According to the driver “EcalRawConverterDriver” the EcalCalHit is the output (and EcalReadoutHit the input), so it seems to me that is the one to use. Also, on Confluence:

EcalCalHitsCalorimeterHitEcalRawConverterDrivercalibrated ECal Hits

Documentation is pretty sparse though, so correct me if I am wrong and need to use a different collection. I find the large number of collection more than a little confusing at times.

Best,
Maurik



On Sep 20, 2016, at 1:51 PM, Omar Moreno <[log in to unmask]> wrote:


​Originally, as Maurik said, the DST maker only wrote Ecal hits associated with a corrected Ecal cluster (i.e. cluster->getCalorimeterHits();)  With Maurik's changes, all Ecal hits written to the DST now come from the collection "EcalCalHits".  The cluster time comes from the seed hit of the cluster so if there was a correction applied to the seed that wasn't propagated to the original EcalCalHits collection, then this might be the issue.  This might be the reason why I didn't write all of the Ecal hits to the DST maker to begin with but I don't remember.

Maurik,  did you look at distributions of Ecal clusters variables before and after your changes in order to make sure that there wasn't any changes?  If not, then we should revert all of your changes and do these checks. 


On Sep 20, 2016 9:59 AM, "Sebouh Paul" <sebouh.paul@gmail.com> wrote:
To get technical, I did not look at the recon LCIO files directly, but rather generated DQM from them.  And the DQM did not look different between the two files.  Now what Nathan had suggested was that possibly the DST maker is reading the hits from a different collection than it was reading from before, for instance uncallibrated hits instead of callibrated hits?  

On Tue, Sep 20, 2016 at 11:21 AM, Omar Moreno <[log in to unmask]> wrote:

Just to make sure, this behavior isn't observed looking at the recon LCIO files correct?


On Sep 20, 2016 7:59 AM, "Sebouh Paul" <[log in to unmask]> wrote:
Without pulse fitting, or the mode7 emulation, all of the hit times would be at times that are multiples of 4 ns, corresponding to the time of the first sample crossing the threshold.  However, we use a pulse fitting algorithm, which improves our resolution on timing for the hit, as well as time-walk corrections.  If a fit fails the pulse fitting and the mode-7 emulation, then we use the time of the first sample that crosses the threshold.   In the "bad files" we see a lot of low energy hits with multiples of 4ns times, which probably failed both these two methods of time reconstruction.  

There is also another thing in here I forgot to mention:  there is also a shift in the timing window of when multiple hits are, between the "bad" files and the "good" files. What i mean is, you'll see a peak in hit time, corresponding to the trigger window.  This peak is shifted between files generated using the old version of the  DST and the new version.  

On Tue, Sep 20, 2016 at 10:47 AM, Maurik Holtrop <[log in to unmask]> wrote:
Hello Sebouh,

There was a bug in the DST maker where it would only write ECAL hits that were part of a cluster, and if a hit appeared in two clusters, it would write that hit twice. This is not the correct behavior. I fixed this in Issue44 (https://github.com/JeffersonLab/hps-dst/issues/44) and then merged to master.

So, #1, is because now the unrelated and out of time hits are also in the DST. 
I don’t think this explains #2. 
#3 Since the FADC samples at 250Mhz, I would expect all ECAL hit times to be at multiples of 4ns, but perhaps I am missing something?

Best,
Maurik

On Sep 20, 2016, at 9:37 AM, Sebouh Paul <[log in to unmask]> wrote:

Has anyone made modifications to the DST maker since pass0 began in June 6?  Nathan ran recon and DST maker on some files at the beginning of August, and there are some problems with the DST files produced:

1)  1.5x more ecal hits per event than in DST files generated in pass0.  
2)  two cluster time difference has a much larger sigma than usual. 
3)  many ecal hits have hit times that are exact multiples of 4 ns.

I ran DQM on the corresponding LCIO files, and saw none of these effects, so the problem must be in the DST maker.  

thanks.  


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