Analysis Launch Plugin Requirements
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To make sure everything works, and to save memory and speed up the analyses, the following restrictions are placed:
Contents
Example
- An example plugin that meets all of the requirements: Paul's γp→K+Λ Plugin
Requirements
General Requirements:
- Plugins must be checked into your home area in: https://halldsvn.jlab.org/repos/trunk/home/
- Plugins and DReactions must have unique names: No one else can use the same names
- E.g.: We can't run 4 plugins / reactions named "omega," so try to do something unique (e.g. "omega_pmatt").
Memory / CPU / Disk Space / Locking Requirements
- Do locking correctly:
- In custom actions: Use action-locks in Perform_Action(), rather than japp.
- In plugin processor: Use plugin-locks in evnt(), rather than japp.
- Don’t use a ton of memory (e.g. many DHistogramActions).
- Try not to abuse memory / cpu / disk space. If too much is being used, we'll cull things as necessary to run smoothly.
Cut Requirements
- All analyses (i.e. DReactions) must use an EventStore skim.
- All channels must have at least the following cuts (or a very good reason not to):
- Beam-RF Δt cut at +/- 0.5*dBeamBunchPeriod (or wider for sideband subtraction)
- Pre-combo loose mass cuts around peak (use same cuts (or tighter) as those in skim (if any))
- Loose PID cuts (each particle & detector)
- Kinematic fit converges (if any): FOM cut at -1.0.
- These cuts must be placed before the kinematic fit is performed (except kinfit confidence level, of course).
- The kinematic fit is performed as soon as the fit results (e.g. 4-vectors, confidence level, etc.) are requested.
Recommendations
Kinematic Fit
- We've seen that the tracking errors are a problem in the FDC.
- You can go ahead and kinematic fit, but just be careful:
- Cut lower on the confidence level than you usually would, and study the signal loss when doing so.
- The measured-p4 may be more accurate than the kinematic-fit p4: Histogram mass peaks with both and see which looks better for your channel
- Be cautious about constraining masses: Once you do, you no longer have an unbiased handle on the background under the peak.
- Mass constraints are on when P4 is fit, unless explicitly disabled
Loose CDC dE/dx Cut
- See the example plugin above.
Loose Timing cuts
- These still let in a lot of background, but cut ~no signal
- It's recommended to apply these loose cuts, and to do your own momentum-dependent Δt cuts later
- γ:
- BCAL: +/- 3 ns
- FCAL: +/- 5 ns
- e+, e-:
- TOF: +/- 1 ns
- BCAL: +/- 2.5 ns
- FCAL: +/- 3 ns
- π+, π-:
- TOF: +/- 2 ns (Wide to accept muons from pion decays)
- BCAL: +/- 2.5 ns
- FCAL: +/- 3 ns
- K+, K-:
- TOF: +/- 0.75 ns
- BCAL: +/- 2.5 ns
- FCAL: +/- 3 ns
- p, pbar:
- TOF: +/- 2.5 ns
- BCAL: +/- 2.5 ns
- FCAL: +/- 3 ns