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Km3 v4r5 and the OPA. C.W.James , AWG meeting 30 Nov 2012. Development version of km3: v4r5. Changes from v4r4 (see Bologna presentation) Use of Nautilus glass Couple of minor ‘bug’ fixes (no real effect expected) Aug25 angular acceptance now standard (not included in official v4r4 release)
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Km3 v4r5 and the OPA C.W.James, AWG meeting 30 Nov 2012
Development version of km3: v4r5 • Changes from v4r4 (see Bologna presentation) • Use of Nautilus glass • Couple of minor ‘bug’ fixes (no real effect expected) • Aug25 angular acceptance now standard (not included in official v4r4 release) • Improved version of OPA should be working properly. • Topics for today: • Show Nautilus glass • Show current v4r5 response to numu_CC events • Discuss OPA • Discuss scattering/absorption C.W.James, AWG telecon, 30th Nov 2012
Benthos Nautilus glass • It turns out that km3 has been using Benthos glass – which was the right thing to do, back in 1998… • Glass absorbs photons • important in modelling the optical modules. • Measurements from: ANTARES-OM-98-1 • Mistake found using comparisons with Heide’s simulations for angular efficiency Original numbers lost to time! C.W.James, AWG telecon, 30th Nov 2012
Comparison of v4r5 to rbr v2 • 40 runs, all numu_CC and anumu_CC events – cumulative distribution. Decrease due to • angular acceptance changes • gen being placed in seawater C.W.James, AWG telecon, 30th Nov 2012 4
Comparison of v4r5 to rbr v2 • Ratio: relative decrease wrt run-by-run v2 • (all three use august 2012 angular acceptance) 5 C.W.James, AWG telecon, 30th Nov 2012
Good news! • The simulations are no longer getting any worse! (or at least, not by very much) • Planned release version of v4r5 (this afternoon?) predicts the same number of muons of neutrino origin as v4r4 • (perhaps very slight decrease due to Nautilus glass?) 6 C.W.James, AWG telecon, 30th Nov 2012
Part 4: Preliminary OPA results(work by M. Dentler) C.W.James, AWG telecon, 30th Nov 2012
One-particle approximation (OPA) q q • Principles: • Can not account for changes in shower shape. • Use gen to run pion showers and compare photon yields W-/W+/Z0 l/νl νl M. Spurio, 2008 C.W.James, AWG telecon, 30th Nov 2012
Preliminary results from OPA investigation • Work finished; 95% of analysis finished; 50% of ‘pretty pictures’ finished. • Shower shape ‘important’ out to ~10m distance, • Pion weights: should be O~100% above 10 GeV C.W.James, AWG telecon, 30th Nov 2012
Fit • A rather complex function… • Fit log10[number of photons at shell 15] as a function of pion energy • Normalise to the number of photons from an electron at energy Ee (proportional to Ee) • Invert: C.W.James, AWG telecon, 30th Nov 2012
Implementation in km3mc • In km3: use: • INOPA 1 • Converts pion energy: • Do not call GEASIM - ever Calls OPA only if the particle is NOT a muon Adds momentum to calculate the mean shower axis Gets OPA weights C.W.James, AWG telecon, 30th Nov 2012
OPA Weights • Weight = 1 for e+-, gamma, pi0, some kaons • Weight = [complex formula] if pi+- • Weight = 0 otherwise C.W.James, AWG telecon, 30th Nov 2012
Should we use the OPA? • Comparison by Mona: • Run full pion shower • Run electron cascade of original OPA energy (constant weight 0.2) • Run electron cascade of new OPA energy (variable weight) • Run pion shower, but only include direct photons • Compare number of photons incident at each shell. What do we get? C.W.James, AWG telecon, 30th Nov 2012
Should we use the OPA? • 35 m C.W.James, AWG telecon, 30th Nov 2012
Should we use the OPA? • 4m – shower shape effect C.W.James, AWG telecon, 30th Nov 2012
Should we use the OPA? • 8m – it’s fine C.W.James, AWG telecon, 30th Nov 2012
Rbr results… • (sadly, still in the queue) • Plan to use dusj shower reco as a test of the OPA in rbr scripts C.W.James, AWG telecon, 30th Nov 2012
Discussion on scattering/absorption [insert discussion here] C.W.James, AWG telecon, 30th Nov 2012