Status of km3 check

ANTARES MC WG, Tue 12th Jun 2012

Km3 Progression: a reminder…• rbr v0.1: used km3 v3r7

– Treated direct photons from electrons as being emitted at the Cherenkov angle• Km3 v3r9:

– fixed ‘single-band issue’• direct photons from electrons treated as scattered photons.• Fix acts to reduce event rate (less ‘on-cone’ hits)

– Fixed ‘energy-loss mismatch’ between gen and km3• Previously, e-loss between 0.3 and 0.72 GeV was discarded• Fix acts to increase the event rate (more eloss in km3)

– v3r10: only cosmetic changes• Km3 v4

– Added chromatic dispersion (no obvious net effect expected)– V4r0 v4r1: buggy. Use v4r2

• rbr v2:– Modify hit v4r2 to use the new angular efficiency via aa.txt and aa.f

Behaviour v3r7-v4r2• Step 1: Use toy experiments to assess behaviour

– Run 3x106 toy events per trial• B1: 1 TeV muon, 25m PMT distance, pointing away• B2: 1 TeV muon, 25m PMT distance, pointing towards• B3: 1 TeV muon, 50m PMT distance, pointing away• B4: 1 TeV muon, 50m PMT distance, pointing towards

– This analysis is complete as of 11:30 am today• Step 2: Use rbr runs

– use exactly the same MUPAGE/GENHEN events (only km3 and TE randomness applies).

– Use 10 runs: 34433, 35360, 35750, 36430, 37230, 37340, 53240, 53450, 53620, 54250.

– Analysis incomplete: 50% computation finished + need to decide how to characterise output

What I did exactly…• v3r7, v3r9, v4r2:

– Check out clean copy and make executables– Build gen & hit tables and run km3 w. standard options– v3rX have ¼ statistics of v4rY (smaller internal arrays)– Gen rad file: gen-water-radii-5-20s-partic-0.0075.dat

• v4r2 rbr:– Tables from /sps/km3net/mc/rbr/v2/prod_inputs/km3tables/

– Use clean co-ed and built km3mc v4r2– May have used a different gen radii file!

• Ran many events on the cluster and got… results!

B2 (1 TeV, 25 m, facing towards)

B4 (1 TeV, 50 m, facing towards)

B1 (1 TeV, 25 m, facing away)

B3 (1 TeV, 50 m, facing away)

B2 (1 TeV, 25 m, facing towards)

B4 (1 TeV, 50 m, facing towards)

B1 (1 TeV, 25 m, facing away)

B3 (1 TeV, 50 m, facing away)

What can we conclude from this?• Not as much as we might expect!– Effect in slides 9-12 due to chromatic dispersion (c-d)(main

diff between v3 and v4 plots)– c-d acts to delay the peak– Of course we then have less photons after a certain time!

• But…– Both v4r2 for cases B1 and B3 (facing away) have definitely

lower cumulative distributions than v3rX– Could this be the source of the reduced counts?

• Q: What is the effect on rbr simulations?• A: Still to find out…

OK, onto the future…• v4r3:– Minimum effang of 10-6 (solves 2nd early-photon problem)– New theta-binning (BELO/BEHI of 0.45) (‘v4r3 pure’)

• Solves early-photon problem• Effect on total photon number: increases it! (no hard reason)

– Added seawater to gen (expect ~4% fewer photons) (‘v4r3 sea’)• v4r4– Wavelength-dependent ‘eta’ (fraction of Rayleigh) (‘v4r4 MR’)– New hit method to input and sample PMT parameters:

implement new effective angle calculation (‘v4r4 new effang’)

B2 (1 TeV, 25 m, facing towards)

B4 (1 TeV, 50 m, facing towards)

B1 (1 TeV, 25 m, facing away)

B3 (1 TeV, 50 m, facing away)

B2 (1 TeV, 25 m, facing towards)

B4 (1 TeV, 50 m, facing towards)

B1 (1 TeV, 25 m, facing away)

B3 (1 TeV, 50 m, facing away)

Conclusion on recent updates• Changes v4r2-v4r3: BELO/BEHI most important• All other changes minsmall

• Effect of new angular efficiency:– v4r2 vs rbr_v4r2 (slides 9-12, blue vs pink)

• slightly reduced number of hits for PMTs facing towards a track• Increased number of hits for PMTs facing away from the track

– v4r4 vs v4r4_new effang (slides 19-22, light blue vs yellow)• Reduced number of hits for PMTs facing towards a track• Increased number of hits for PMTs facing away from the track

– This is inconsistant!

Effang plot

Difference can not be due to different implementations of the effective angle!

Further check…

Possible explanation?– When compiling km3 with the function ‘getaa’, I had to

remove all binaries and recompile from scratch to avoid insanity.

– There is no known reason for this behaviour: could be f77 or make problem.

– Perhaps something strange gets introduced here?

Where commeth the wobbles?

• Scattered photons from muons!

Why?• Speed up in km3: merge muon track segments at large

distances for scattered photons– Tracks: intrinsically 1m– Merging: x3, x9, and x27 at comparable distances– Merging is too coarse!

• Solution: – multiply all merging distances by a factor– Implementation: allow FFKEY ‘DIVTK [float]’ to km3

• Test: use DIVTK 2. in B4

Problem solved

• DIVTK=2 seems to work!