Physics Trigger in protoDUNE: Function and Performance David Last, - - PowerPoint PPT Presentation
Physics Trigger in protoDUNE: Function and Performance David Last, David Rivera, and Jonathan Sensenig June 6, 2019 Physics Performance Meeting 0 Outline Overall Trigger Structure Our Physics Trigger for protoDUNE
David Last, David Rivera, and Jonathan Sensenig June 6, 2019 Physics Performance Meeting
Overall Trigger Structure Our “Physics” Trigger for protoDUNE Offline Algorithm Efficiency Current Status/Developments Discussion: How to measure online physics performance
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Our efforts have been focused on the process of making these decisions in the last two stages. Candidate Algorithms Module Trigger
50 microsecond Clustering Window (D. Rivera: DUNE-doc-9808-v1):
Unlikely to get high pile-up from 39𝐵𝑠
TPC Summed ADC (TADC):
Total Sum of primitive Summed ADC over all ticks above threshold in one
TPC
Utilize maximum between two TPCs per Clustering Window
Adjacency/Clustering*:
Two different methods for Counting Wires hit in a time window
Time Over Threshold in ticks (TOT):
Single-wire, single-primitive maximum per Clustering Window
Wire ADC (WADC):
Single-wire, single-primitive Summed ADC maximum per Clustering
Window
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*- Focus on Adjacency for now due to computation speed.
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WADC Modified (due to chosen nomenclature) from David Rivera’s talk on the Data Selection Call
z x y
Define “horizontal”: Crossing all APAs on the same side of the
TPC which have online hit-finding/trigger primitive geneartion
Take Candidates with high adjacency (threshold discussed in
later slides)
When a Candidate is issued, the end points (channel and time
points) of the largest adjacency (cluster size) of wires are saved as part of the candidate
“Stitch” together the tracks, and issue trigger if “sufficiently”
crosses all APAs
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54,000 100 GeV Horizontal Muons (Crossing APAs instrumented with FELIX),
with SCE.
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This is a top-down view with left as upstream. Cathode in the center.
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Collection Wire Tick
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Collection Wire Tick 50 us
Distribution of all non-empty APA*windows for APAs instrumented with FELIX
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Take All Candidates in an Event where Adjacency Exceeds
(or equals) 50
Call two Adjacent-In-Time Candidates “stitched” if the
following are true:
Up to gap of 1 in channels hit Gap of no larger than 2 ticks in time (10 ticks if across
APAs)
Slope of “track” different from previous slope by no
less than 5% of largest possible slope
If total “stitched track” has at least 450 wires hit in both
APAs (presently instrumented), issue trigger
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Current allowed channel gap sizes are a bit unrealistic,
but tunable as necessary
The stitching is done in increasing time order of
candidates:
The direction of successful tracks is monotonic in the channel-tick
plane on large scales
Could lose horizontal muons to small scatter Could lose horizontal muons due to large scale space charge
effects 11
Present Efficiency for triggering: Primitive Threshold ADC 15: ~10% Primitive Threshold ADC 18: same order, about 1% more
efficient that threshold 15
Above, unexpected (more efficient higher threshold) result
being sorted out:
There is a possible physics explanation. Magnitude of efficiency likely due to being stringent conditions
chosen to avoid fake triggers
Trigger Candidate Output is generally as expected: ~54% of all non-empty windows (many in that tail near 0)
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Sort out the source of the efficiency differences between
thresholds
Test algorithm on random trigger data to get an idea of overall
trigger rates/Limit rates as necessary
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Structure of first-implementation MLT exists, is listening to hits In progress confirmation that correct TPC data is being
requested
Structure of TCBR in development Hit sets need to be windowed into physically meaningful
chunks, in development
Once windowed, implement physics-based selection:
Start with basic (e.g. nhits) and work up to more complete
implementation of discussed horizontal muon trigger
Unknown if other physics triggers in development
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Compare percentage of “offline triggers” in random trigger data to
horizontal muon-triggered data (very basic test)
Look at event displays of horizontal muon-triggered data (time-
consuming, arguably more rigorous)
Utilize CRT information independently tag events (Need to be careful
about geometries):
Could be used similar to point 1 on this slide Could be used to measure expected rate to compare to trigger rate
Other Suggestions/Ideas?
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A Test that, if possible, I would want to do in protoDUNE while the beam is off. See what the current trigger candidate algorithms calculate in terms of its decision variables for windows that don’t contain cosmics. Essentially, issue a candidate for every window with a random trigger turned on so that all the calculated information is output, and then offline determine which windows had cosmics in them, so that we have a characterization of how the trigger candidate algorithms see noise/radiological
cosmogenic neutrons, but all that does is give a more conservative estimate.
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MOST IS IN OVERFLOW…
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