COMA

Last update: 19 Nov 2024 [History] [Edit]

COMA provides quick information about data in containers, periods, runs, and luminosity blocks, and is a tool that aggregates information from across many runs. It is a useful tool to get an overview of the configurations of streams and triggers.

To access the COMA web portal you need a valid grid certificate in your browser and you need to be a part of the ATLAS virtual organization (VO) (tutorial instructions). When trying to access the web portal accept any site warnings and click OK (not CANCEL)

Understanding data periods

Exercise

Use the COMA web portal to find out what were the data periods in 2017 for 13 TeV pp collisions. What happened in period E (i.e., what defines period E)?

Instructions

There are likely several ways to find this answer. One way is the following:

  • from the main page click on COMA Period Menu
  • in the new page, under by Project, click on data17_13TeV
  • in the new page, click on [A:N] in yellow under AllYear

You will see the listing of periods (and associated information) for periods A to N. In period E the Description column states:

Runs after the switch of the online release to 21.1.10

If you click on [E1:E8] in yellow under E, you will see what was going on in each sub-period: more bunches were being added to the ring, up to the maximum (2208).

Determine lowest unprescaled trigger

Exercise

Use the COMA web portal to find the lowest pT HLT unprescaled single muon trigger throughout the 2017 pp run. What was the corresponding L1 input item?

Instructions

From the main page click on COMA Report Menu and fill in the following fields:

  • Project: data17_13TeV
  • Chain/Item: HLT_mu*

And click the SUBMIT button at the bottom left.

Expand the Distinct Triggers yellow link. You’ll have to scroll (or do a clever search) to find the answer: HLT_mu15.

The corresponding L1 input item was L1_MU11.

There are other lower momentum triggers that are listed on the page. Some of these have prescales: HLT_mu10 has a prescale between 39.4 and 15717. That means we record only a portion of the available data with that trigger. Some triggers have quite long names; it can be useful to become comfortable reading these so that you know what they mean. Because “what is the lowest unprescaled trigger” is a very common question, the trigger group maintains a Twiki page with the full list of lowest unprescaled triggers in all periods.