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Recent Updates on One-Particle Approximation Testing and Performance in ANTARES MC

This document summarizes updates from a teleconference held on January 10, 2013, regarding the one-particle approximation (OPA) testing results for the km3.v4r5 software version. Key highlights include successful testing of the OPA under various conditions, such as modified absorption and scattering lengths, and improvements in simulation efficiency. The document discusses ongoing challenges and preliminary outcomes of the energy reconstruction processes. Future implementation of modifications and further optimization strategies are also outlined for potential improvements in simulation accuracy and efficiency.

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Recent Updates on One-Particle Approximation Testing and Performance in ANTARES MC

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  1. Km3 v4r5 update C.W.James, AWG telecon 10th Jan 2013

  2. Updates this telecon • Completed one-particle approximation testing • Results of ‘dusj’ using v4r5 w/wo OPA • Test effects of: • Increasing absorption and scattering lengths by 10% • Also check increasing absolute OM efficiency by 5% • Still to-do: • Implement read-out of hit tables for SIRENE • + New modifications requested C.W.James, ANTARES MC telecon, 10th Jan 2013

  3. One Particle Approximation – a reminder • Replace all non-muonic products with a single electron of ‘equivalent’ energy • Why? • Allow km3mc to handle shower events • Allow treatment of scattered photons for showers • Speed up simulations! • Finally, I’ve ironed out all the bugs (touch wood!) C.W.James, ANTARES MC telecon, 10th Jan 2013

  4. OPA results – it works! • Testing: • Used new km3 v4r5 (in development) • Compared run-by-run reconstruction chain using A: geasim, and B: km3 with the OPA, to simulate cascade events. • Used: 100 runs x [a]nuc_[CC/NC]_[a/b] and [a]_numu_NC_[a/b] files (12) per run: 1200 in total. • Used identical vertex inputs. • Processed with ‘dusj’ (F. Folger) shower reconstruction method to compared results. • Full sets of plots (>30) are found in the material on the web-site: • “v4r5_geasim.pdf” and “v4r5_OPA.pdf • BIG thanks to Florian Folger here! C.W.James, ANTARES MC telecon, 10th Jan 2013

  5. Summary of changes • Vertex position and direction reconstruction behave very similarly (plots #1-6). • Energy reconstruction for the OPA has a larger systematic offset but a small variance (plot #7). • Tends to reconstruct late vertex times (because some late, scattered photons are seen!) • OPA less efficienct above 100 TeV – why? • Coincidentally (or not!), this is where GEASIM’s one-particle-approximation kicks in – which is known to underestimate the number of photons by a factor of 5. • Overall loss of OPA efficiency: 10%. • But to what degree was the current dusj version tuned on incorrect MC data w/o scattered photons? C.W.James, ANTARES MC telecon, 10th Jan 2013

  6. Summary of changes • Dusj(GEASIM) vsdusj(OPA) – different dependencies on shower energy observed (plots #19-22). • More discussion with Florian in order to understand these points, and plots #23+. • Conclusion on accuracy: • “similar” (sometimes better, sometimes worse) • Might be improvable by adapting a new dusj version to the next run of rbr data. • Expectation: more accurate! • What about run-time? • Will save ~6 hr per run! C.W.James, ANTARES MC telecon, 10th Jan 2013

  7. Conclusion on OPA • OPA status: • Uses M. Dentler’sparameterisation for pions • Applied to all non-muonic events • We now have scattered photons for shower events, hurray! • Test results: • no great difference in shower reco accuracy • Some subtleties still need understanding • Expectation: • differences are because km3mc gets it right! • need e.g. clsim to decide definitively. • Release v4r5 with OPA on by default. • No need for GEASIM in Antares simulations! • OPA might not OK forORCA • will be perfect of km3net • Last question: which particle ID for OPA showers? C.W.James, ANTARES MC telecon, 10th Jan 2013

  8. Fiddling around with parameters • Question: What is the effect of changing X on Y? • X = scattering length, absorption length, optical module absolute efficiency • Y = downgoingmuon rate, upgoing neutrino rate • Assess using… • 10 runs for downgoingmuons • 40 runs for upcoming neutrinos ([a]numu_CC) • Full run-by-run MC treatment; look at Aafit results • Motivation: understand the magnitude of the effects • NOT physically motivated – this is NOT intended to make recommendations about the physical truth! C.W.James, ANTARES MC telecon, 10th Jan 2013

  9. Increasing scattering length • Changing the scat length • Lscat’(λ) = Lscat(λ) x 1.1 • This is not physical – it is Monte Carlo! • Eta (fraction of scattering off seawater) is an unchanged function of wavelength • Absorption length left unchanged • Param set: C.W.James, ANTARES MC telecon, 10th Jan 2013

  10. Increasing scattering length • Changing the scat length • Labs’(λ) = Labs(λ) x 1.1 • This is not physical – it is Monte Carlo! • Scattering length left unchanged • Param set: C.W.James, ANTARES MC telecon, 10th Jan 2013

  11. Increased OM area • Increasing OM collecting area • Actually 5% more photons produced per track • Equivalent to 5% larger PMT area • Difficult to compare quantitatively to changing absorption/scattering lengths (not distance dependent) • No wavelength-dependence: • no plots here • use meaningless sub-points to take up otherwise ugly white space • put this point in italics to make it look more meaningful C.W.James, ANTARES MC telecon, 10th Jan 2013

  12. Results – atmospheric muons (up and down) Notes: • Cumulative distribution left-to-right • Errors bars are correlated between colours and over-estimates C.W.James, ANTARES MC telecon, 10th Jan 2013

  13. Results – muon CC neutrino events Notes: • Cumulative distribution left-to-right • Errors bars are correlated between colours and over-estimates C.W.James, ANTARES MC telecon, 10th Jan 2013

  14. Partial derivatives at lambda=-5.4 • Atmospheric muons • [a]numu_CC (ignoring error bars – I will get round to fixing this problem soon*!) *cosmologically speaking C.W.James, ANTARES MC telecon, 10th Jan 2013

  15. Conclusions on km3 v4r5 w OPA to be released soon. Hurray! Effects of changing water parameters measured. New set of water properties still undecided - I think we should have a dedicated face-to-face meeting on this. Oujda? Somewhere/when else? C.W.James, ANTARES MC telecon, 10th Jan 2013

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