Instructions for analysis shifts

Instructions for analysis shifts / VCS E12-15-001 experiment

• Connect to cdaql1: ssh cdaql1 and go to /home/cdaq/vcs2019/hallc_replay_vcs

Warning: from this directory, please don't make any modifications on the source code. If you want to do tests or modify things, go to github and fork to your personnal directory. The source code is available from: https://github.com/JeffersonLab/hallc_replay_vcs Before starting to run it after getting your fork, run: "getstarted.sh"

Kinematic setting

- For each new run, the file: DBASE/COIN/standard.kinematics is updated. Check regularly if it is the case: electron momentum needs attention.

- If needed to manually enter a new run, type new values for: beam energy (in principle it won't change), target mass (amu), HMS and SHMS central momentum and angle, particle mass detected in each arm (in principle, it won't change: proton in HMS, electron in SHMS). Note that the names of arm variable start with letter "h" for HMS and "p" for SHMS.

Analysis monitoring

This step should be done by the TO, if nobody on analysis shift. Any regular TO tasks have the highest priority over analysis replay and if target needs attention, the TO should just take care of the target and not do the analysis replays.

- After ~100,000 events run the "partial" analysis replay:

> ./run_partial_replay.csh (run number) (# events) (process = elastic, vcs...) (target = LH2 or dummy)

After the run is finished, run the full replay (don't run again partial replay after that):

> ./run_full_replay.csh (run number) (process = elastic, vcs...) (target = LH2 or dummy)

These scripts will convert coda to root files from regular hcana, build databases, run analysis monitoring and apply a first filter on the data. If a second monitoring is needed or if you need to change a cut in analysis (see below the time delay), start only at the level of the analysis script without rebuilding the root files.

• Changing a cut: edit Ana/ANA_CUTS.input (write a note if you need to change another cut than the coincidence time delay).
• Changing histogram limits or binning: edit Ana/ANA_HIST.input
• Please don't change any source code in this directory.

Run from analyzer only:

> ./run_ana_only.csh (run number) (# events) (process = elastic, vcs...) (target = LH2 or dummy)

The source code is in the Ana directory. Read instructions on Ana/README.txt if you would like to run directly the code.

Things to check

All the monitoring information will be open automatically at the end of the replay. Check additionnal information if needed from text and pdf files. Look carefully at the prints on the terminal at the end of the job, it will tell you what to look at.

 1) Timing cuts

- This file is open automatically. If not, open: Ana/files/timing_(run).dat

→ the first line is information about the selected coincidence time peak in order: peak position, charges – bkg, events in time peak, bkg (low), bkg (up), peak max

- check if the peak position is < 0.1. If not, this means the coincidence time is not set properly. Change it in Ana/ANA_CUTS.input and run again the analyzer

- check that the number of events in the peak is larget than the numbers for "bkg (low, up)"

- enter the value of "event – bkg" in the run database

- Look if there is a secondary or third peak: line 2 and 3 correspond to potential physics peaks. If the value of charges - background is significant, compare values of charges in peak and average background (up, low). If the number of charges in this peak is significantly higher, enter it in the run database and enter the peak position

- If no peak is found, try to figure out why:

Possibilities: look at the figures with coincidence time minus the time delay to be set, look at the absolute coincidence time, check the quality of the fit and of the peak finder (monitoring figures, see below), change cuts and replay the analyzer... It may also be that there are not enough events in this run: check the luminosity, the running time. Look if there is any obvious reason for the number of events to be low. First check histograms, and make a log entry and/or write it is database and/or the run sheet if anything is wrong and/or write it in the database and the run sheet. Call the expert if needed to avoid loosing good data.

2) Luminosity

- This file is open automatically. If not, open: Ana/files/lumi_(run).dat The one line contains: run number, luminosity (HMS), luminosity (SHMS), actual running time (HMS), actual running time (SHMS), current (HMS), current (SHMS)

- check if the luminosity are the same in HMS and SHMS, and write them in the run database. If there are different, try to figure out why and call expert if needed.

3) Missing mass peaks position

- This file is open automatically. If not, open: Ana/files/missmass2_(run).dat

3 lines correspond to possible 3 found peaks in the squared missing mass, with entries:

M², integral, sum events+bkg 3sigma, integral/lumi_HMS

- record the position of the 2 main peaks: VCS M² ~ 0 GeV² and π° M² ~ 0.02 GeV² and the integrals int(VCS) / int (π°)

- if the ratio doesn't make sense and is far from ~ 1/10, check the quality of the fit and/or try to understand. If something is wrong, write it in the database and/or run sheet.

- if less than one peak is found, or the 2 peaks (VCS and π°) are merged into one, it may be a problem with the calibration, resolution... Try to understand why. If the problem is very bad, write in database and run sheet.

4) Monitoring plots, to compare with reference plots

All the figures to look at will pop-up in a condensed replay "ana_monitor_(run).pdf. If additionnal check need to be done, open the extra pdf files as indicated.

• Timing

Extra monitoring: Ana/Results/cointime_(run).pdf

→ Look at the coincidence time distribution for ROC2: if no peak is found there is a problem. If no peak is found near 0 and/or no peak for the red curve, change the time shift in ANA_CUTS.input and replay the analyzer.

→ Check the quality of the peak finder and the fitting

→ Compare β and missing mass distributions to reference

• Kinematic distributions

Extra monitoring: Ana/Results/kinematics_(run).pdf and Ana/Results/kinematics2D_(run).pdf

→ Compare the figures with reference plots for each kinematic setting.

→ Check also Ana/Results/positions_(run).pdf if something strange. If the HMS and SHMS positions don't match expectation from run plan, figure out why and/or call an expert.

• Exclusivity distributions

Extra monitoring: Ana/Results/exclusivity_(run).pdf (multipage)

→ Compare selected data exclusivity distributions to the reference

→ Check if there are 2 missing mass peaks on the missing mass and squared missing mass distributions corresponding to 0 mass and π° mass, compare to the reference

• Analysis root data

A root file has been created and contains filtered data. If histograms are empty and/or the tree is empty or don't contain a significant number of events after a full replay, it can come from cuts badly set, from not the good option being called, from database information not properly filled or from a problem with the data.

> root -l Ana/files/HallCdata_(run).root

> (root) > HallCTree->GetEntries();

> (root) > HallCTree->Show(0);