Regions-of-Interest, Data Reduction and Trigger Rates for DUNE - - PowerPoint PPT Presentation

Regions-of-Interest, Data Reduction and Trigger Rates for DUNE

Josh Klein, Penn, 11/25/2019 DocdB #16982

The Question

If storage were not an issue, at what trigger rate does the Event Builder become the bottlenecK? There are always questions about how high a trigger rate we could actually sustain:

• Calibration data
• 39Ar monitor/calibration
• Low E physics (solar ns, ?)

So we asked Data Flow:

The Question

At what trigger rate do you want the bottleneck to be? There are always questions about how high a trigger rate we could actually sustain:

• Calibration data
• 39Ar monitor/calibration
• Low E physics (solar ns, ?)

Kurt responded:

Big Picture

Our overall data rate is > 9 Tb/s per 1 SP module=35.5 EB/year So about 1000 times bigger than our allocation (before any compression)

Three choices to bring down to acceptable levels:

• 1. Bias the channels
• 2. Bias the trigger
• 3. Bias both

Big Picture

Our overall data rate is > 9 Tb/s per 1 SP module=35.5 EB/year So about 1000 times bigger than our allocation (before any compression)

Three choices to bring down to acceptable levels:

• 1. Bias the channels
• 2. Bias the trigger
• 3. Bias both
• This choice simplified our effort up to the TDR (and perhaps beyond)
• And makes analysis simpler than Option 3
• If trigger bias is small (e.g., low threshold, steep turn-on) then this is a good choice
• And this follows the rest of the DUNE philosophy (no FE ZS, for example)

Big Picture

• D. Rivera

For high-energy physics, this appears to be true Analysis threshold for LBL is 500 MeV (Evis)

Physics Opportunities?

Storage cap Moving threshold lower could catch 8B solar but there is a small window before we hit the

• neutrons. We need 4 orders-of-

magnitude rejection of those unless their rate is a lot lower than we think.

The Question

• But maybe the neutrons will be shielded down to 10 Hz…
• And Lasorak and Rivera have shown that cluster-finders are

~10x more efficient for neutrino events than neutrons (3%).

• Or we get even more creative

So, what are the trigger rates if we start to bias the channels to reduce the data volume/event?

The Question

• But maybe the neutrons will be shielded down to 10 Hz…
• And Lasorak and Rivera have shown that cluster-finders are

~10x more efficient for neutrino events than neutrons (3%).

• Or we get even more creative

So, what are the trigger rates if we start to bias the channels to reduce the data volume/event? And then, KURT, how much would it cost for EB to handle it? Or other bottlenecks in the system?

Big Picture

(In fact, as Giovanna points out, table does not include the overhead of headers and error bits, which push the 6.075 GB/event to > 7 GB/event).

• I assume x2 compression because that is min reqd in current scheme
• Not every possible scheme we could imagine (so be patient)
• Ignores supernova triggers

Big Picture

Every additional bias requires an efficiency measurement:

• Standard candle (none of these)
• Calibration source (we may have none of these; PNS could work)
• Zero-bias trigger or lower threshold/prescaled studies
• Complete and tested Monte Carlo
• We never get back what we lose (different than analysis efficiencies)

Additional logic means more corner cases

• There are always boundaries in the logic

And possibly reconstruction/analysis studies

So more bias should come with a strong motivation or low risk

Current Rate Limit

With x2 compression and total volume =4x SP data volume Maximum trigger rate is 0.078 Hz.

(With real overheads it is ~20% lower than this)

Reducing Readout Window

• Actual drift time at full field is 2.25 ms
• We multiplied by 1.2 to be extra safe
• Then x2 because of start/end ambiguity for trigger

More bias is bad unless it really really cuts nothing…

• But at 10 MeV threshold, trigger ambiguity is << drift time
• So if 5.4 à 2.7 ms (keeps 20% conservative buffer)

Maximum trigger rate is 0.156 Hz.

This change leverages no new known physics, but makes analysis faster (And maybe it is a little less embarrassing).

Trigger Candidate APA Localization

We already create candidates on an APA-by-APA basis

So why store data from APAs that have no coincident candidates?

(because candidate threshold may be above interesting secondaries, etc.)

• If cosmics still dominate (unlikely) then on average we would

store 6 APAs (Rodrigues)à1.95 Hz

• If we lowered the threshold then we are dominated by single

APA eventsà11.7 Hz This change might leverage 8B neutrinos (see Rivera memo)

(Effective) Zero Suppression

(See Phil’s talk)

• Take 100 µs around every “hit” and assume we are

dominated by 39Ar singles (at 10 MBq/10 ktonne)

• Assume half of 39Ar above threshold
• And noise is much smaller than this rate
• Then each 5.4 ms snapshot has 135,000 hits
• And therefore 0.04 GB/event (not including overhead)

Maximum trigger rate is ~12 Hz.

• “Natural” way to do this is to re-capture TPs
• Use them to identify hits associated with TCs
• PTMP can buffer TPs for post-trigger access
• (See Brett’s very nice diagram of this “epicycle”)

(Effective) Zero Suppression

(Effective) Zero Suppression

“Toward(s) Data Selection Algorithms” December 11, 2017

Trigger Candidate Localization and Zero Suppression

What is the most extreme possibility…?

• High data volume for zero suppression caused by singles
• APAs are big; forget about the ~2400 wires without hits
• So only keep trigger candidates and only 100 µs around these

Assume we are now dominated by radiologicals…maybe we hit 50 channels per event…? Event size is now ~15 kB, maximum trigger rate is 32.5 kHz Collect large sample of 8B ns, neutrons, 42Ar, 40Cl, and (maybe) pep ns This assumes signal ID on induction wires is efficient before processing

Summary

• Plenty of possibilities to reduce data set
• Not a very steep curve for more physics
• Not clear what this gets beyond just saving

TPs (if we generate induction TPs)

• But should not design system that precludes

these (with future money and effort)