Comparisons of data/mc using down-going muons

1. Comparisons of data/mc using down-going muons Jon Dumm, Chad Finley, Teresa Montaruli UW-Madison April 26, 2007

2. Outline • Low level • Time differences between NN DOMs, Occupancies, Nchan, Nstring • Reconstruction level • Zenith, Azimuth, residuals, Quality cuts (Ndir, Ldir, paraboloid sigma)

3. Data sets • Down-going muons (~0.5M) with high quality reconstructions • 34-fold muon-llh, gulliver, paraboloid • Data for comparison (~ 1 hr livetime) • IC9 minbias data from June 2006 • Corsika Simulation V01-09-06, datasets 296, 394 • Both single and coincident muons • Cuts • Trigger level (Cleaned) • Hard Cuts • Sigma<3 deg, Ndir>9 • ~11% signal efficiency (E^-2), ~95% background rejection

4. Time difference between NN DOMs Sim LC window Exp LC window (ns) Known problem: wrong LC time window!

5. Zoomed in on time difference (ns) This plot tells us about hole ice properties – local scattering near DOMs.

6. Occupancy – trigger Frequency each DomID is hit Format for remainder of talk: -Data vs corsika+doublemu = total sim -No normalization. Real rates as given. Structure washed out in sim Ratio of Exp / Sim 0 ~ 1450m 60 ~ 2450m Not enough light near bottom of IC in sim

7. Nchan – trigger Number of DOMs hit in an event Cut at Nchan<46 for blindness Difference gets worse at higher Nchan

8. Hard cuts = Sigma<3, Ndir>9 Nchan – hard cuts Number of DOMs hit in an event Even with cuts, the difference at high Nchan does not quite go away

9. Nstring – trigger Number of strings hit in an event Similar to the difference at high Nchan but worse!

10. Hard cuts = Sigma<3, Ndir>9 Nstring – hard cuts Number of strings hit in an event

11. Zenith - trigger Reconstructed zenith given by paraboloid The rates of mis-reconstructed events are underestimated by simulation Ideally, we need to find a way to oversample these fakes to save CPU time

12. Hard cuts = Sigma<3, Ndir>9 Zenith – hard cuts Reconstructed zenith given by paraboloid In order to test background rejection, may need weighted corsika sample near horizon

13. Azimuth - trigger Reconstructed azimuth given by paraboloid Structure is from having only 9 strings

14. Hard cuts = Sigma<3, Ndir>9 Azimuth – hard cuts Reconstructed azimuth given by paraboloid

15. Time Residual Time Residual = (Observed time – expected time) given Cherenkov cone and track Remember, simulation LC window at 500 ns instead of 1000ns

16. Time Residual at two depths DomID 45 ~ 2300m DomID 5 ~1600m Keep in mind, there is an LC time window problem after 500 ns

17. Ndir - trigger Direct hit time window: -15 ns <residual time <+75 ns 1 hit per DOM (first hits) Difficult to hope for agreement without agreement in Nchan

18. Ndir – hard cuts Hard cuts = Sigma<3, Ndir>9 Direct hit time window: -15 ns <residual time <+75 ns 1 hit per DOM (first hits)

19. Ldir - trigger Length of direct hits along track μ Ldir Direct hit Good agreement, but not ideal for IC9 since the detector is asymmetric

20. Ldir – hard cuts Hard cuts = Sigma<3, Ndir>9 Length of direct hits along track μ Ldir

21. Paraboloid Sigma - trigger Paraboloid samples the likelihood space around the track and fits it to a paraboloid. Sigma is the circularized width of this paraboloid. L Sigma θ,φ There have since been further improvements in paraboloid for higher efficiency

22. Hard cuts = Sigma<3, Ndir>9 Paraboloid Sigma – hard cuts Paraboloid samples the likelihood space around the track and fits it to a paraboloid. Sigma is the circularized width of this paraboloid. L Sigma θ,φ

23. The End • We have some confidence in our quality cuts for IC9 analysis • Fix LC bug and reprocess • We need to standardize these comparisons for all to see • avoid making it too long and painful to be useful