1. Km3 v4r5 OPA update C.W.James, AWG meeting 17 th Dec 2012

2. Notes from last telecon (30 th Nov) Complete one-particle approximation testing Test effects of:  Increasing absorption length by 5%  Changing the low-cos-theta angular acceptance Still to-do: Implement read-out of hit tables for SIRENE + New modifications requested C.W.James, AWG telecon, 17 th Dec 20122

3. OPA testing This has gone slowly!  Results for showers less well known  Finding bugs takes longer Simulation chain:  Take 100 runs (need more stats for showers)  Simulate shower events nue, anue, numu, anumu 2 CC (nue & anue ) +4 NC (all) ‘a’ (100-1e5 GeV) and ‘b’ (5e4-1e8 GeV)  Evaluate these 12x100 files using Km3v4r5+geasim Km3v4r5 w OPA (no geasim)  Process w standard reco + dusj shower reco C.W.James, AWG telecon, 17 th Dec 20123

4. Other particles in OPA Example file: ~1 PeV electron-neutrino Pions, photons – and an anti-neutron! C.W.James, AWG telecon, 17 th Dec 20124

5. Treating non-standard particles New OPA 1 st run:  Charged pions: w(E) according to M. Dentler (was 0.2)  Neutral pions, gammas, electrons, K0 (short and long): w=1  Others: w=0 Physical problems:  K0 expect to interact before decaying (t_0 c = ~3cm for K0 short, >100m for K0 long)  K0: decay branching ratio to EM-only products ~30%  Other mesons/bosons also interact to produce ‘hadronic’ – and hence electromagnetic – products Trial solution: treat all GEANT IDs >= 8 as charged pions C.W.James, AWG telecon, 17 th Dec 20125

6. Results… still being run! If everything goes well, in one day I will have proper comparison plots Current philosophic question:  OPA uses particle kinetic energy to estimate Cherenkov yield  Charged pion fit -> minimum at 0.2 GeV (approx rest mass).  At low energies, other particles will behave similarly relative to their own rest masses.  How to estimate this? Does NOT matter for ANTARES/km3net WILL matter for ORCA C.W.James, AWG telecon, 17 th Dec 20126

7. Results on angular efficiency Use different low a_effs: Run 4x10 6 runs with OPA facing away from the Cherenkov angle. C.W.James, AWG telecon, 17 th Dec 20127

8. Results on angular efficiency Results: photon arrival-time histograms C.W.James, AWG telecon, 17 th Dec 20128

9. Results on angular efficiency Results: histograms near the peak C.W.James, AWG telecon, 17 th Dec 20129

10. Results on angular efficiency Results: total number of photons C.W.James, AWG telecon, 17 th Dec 201210