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

2. Outline Low level Reconstruction 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 V , 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 Ratio of Exp / Sim 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. Nchan – hard cuts Hard cuts = Sigma<3, Ndir>9
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. Nstring – hard cuts Hard cuts = Sigma<3, Ndir>9
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. Zenith – hard cuts Hard cuts = Sigma<3, Ndir>9
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. Azimuth – hard cuts Hard cuts = Sigma<3, Ndir>9
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. Paraboloid Sigma – hard cuts
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