Km3 v4r5 update

Km3 v4r5 update

C.W.James, AWG telecon 10th Jan 2013

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 2

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!)


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!


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?


Summary of changes

• Dusj(GEASIM) vs dusj(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!


Conclusion on OPA• OPA status:

- Uses M. Dentler’s parameterisation 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 7

Fiddling around with parameters

• Question: What is the effect of changing X on Y?

- X = scattering length, absorption length, optical module absolute efficiency

- Y = downgoing muon rate, upgoing neutrino rate

• Assess using…- 10 runs for downgoing muons- 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!


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:


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:


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


Results – atmospheric muons (up and down)

Notes:- Cumulative distribution left-to-right- Errors bars are correlated between colours and over-

estimates


Results – muon CC neutrino events

Notes:- Cumulative distribution left-to-right- Errors bars are correlated between colours and over-

estimates


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


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?


Km3 v4r5 update

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