STAR QA Board

["Van Buren, Gene" <gene@bnl.gov>]

Hi, QA-ers

On the topic of modifying QA codes for the forward triggers...

On Jan 7, 2022, at 1:56 PM, Ting Lin via STAR-QAboard-l <star-qaboard-l@lists.bnl.gov> wrote:

3. Current offline QA need TPC vertex, but many FWD triggered events do not have TPC information.
  1) Including the FWD tracking can help offline QA.
  2) For FCS, can change to include hits without TPC vertex: plots for events have TPC and events do not have TPC.

I spent some time implementing this, perhaps before I should have. Testing the code, I came to realize that the st_fwd file stream is typically composed of somewhere around 5-20% events having TPC (I checked all the FastOffline data from the past week). An exception is that all the st_fwd_adc file stream events (100%) have TPC as the "adc" refers to having TPC adc information. Anyhow, it certainly isn't something like 50% or more of events having TPC.

The vast majority of plots that the QA shift examines are tracking-related plots. There are a few MTD, BEMC, and FCS plots too, and some TPC hit plots. Currently, the tracking plots are only filled if a "good" primary vertex is found, but other plots (even other subsystems not examined by the shift crew, such as BTOF and EPD) are still filled without that criterium.

The change we discussed today was to possibly include events in all QA plots even if the primary vertex isn't found. But in pp500 data, essentially _all_ events with TPC data satisfy the criteria of a found "good" primary vertex (there are often more than 20 found vertices). Adding events without a "good" primary vertex is essentially equal to adding events without the TPC. And adding events without the TPC is equal to filling the tracking histograms with "0 tracks" entries. This has the effect of making those histograms useless as you can't see anything but the highly filled 0 bin. I see no benefit to this.

So, unless I hear some additional counter-argument, I'll leave the criteria for filling histograms unchanged. I think this brings us back to the question of what people want to examine for QA purposes from the forward triggers. Perhaps we're ready now for what's worth examining until (1) sTGC plots come along, (2) FST plots come along, and (3) forward tracking comes along and really changes things significantly.

Thanks,

-Gene