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Comparisons of data/mc using down-going muons

Jon Dumm, Chad Finley, Teresa Montaruli

UW-MadisonApril 26, 2007

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Outline

• Low level– Time differences between NN DOMs,

Occupancies, Nchan, Nstring

• Reconstruction level– Zenith, Azimuth, residuals, Quality cuts (Ndir,

Ldir, paraboloid sigma)

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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

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Time difference between NN DOMs

Known problem: wrong LC time window!

Exp LC window

Sim LC window

(ns)

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Zoomed in on time difference

This plot tells us about hole ice properties – local scattering near DOMs.

(ns)

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Occupancy – trigger

Structure washed out in sim

Ratio of Exp / Sim

Not enough light near bottom of IC in sim

Format for remainder of talk:

-Data vs corsika+doublemu = total sim

-No normalization. Real rates as given.

Frequency each DomID is hit

0 ~ 1450m 60 ~ 2450m

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Nchan – trigger

Cut at Nchan<46 for blindness

Number of DOMs hit in an event

Difference gets worse at higher Nchan

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Nchan – hard cutsHard cuts = Sigma<3, Ndir>9

Even with cuts, the difference at high Nchan does not quite go away

Number of DOMs hit in an event

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Nstring – trigger Number of strings hit in an event

Similar to the difference at high Nchan but worse!

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Nstring – hard cutsHard cuts = Sigma<3, Ndir>9

Number of strings hit in an event

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Zenith - trigger

The rates of mis-reconstructed events are underestimated by simulation

Reconstructed zenith given by paraboloid

Ideally, we need to find a way to oversample these fakes to save CPU time

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Zenith – hard cutsHard cuts = Sigma<3, Ndir>9

In order to test background rejection, may need weighted corsika sample near horizon

Reconstructed zenith given by paraboloid

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Azimuth - triggerReconstructed azimuth given by paraboloid

Structure is from having only 9 strings

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Azimuth – hard cutsHard cuts = Sigma<3, Ndir>9

Reconstructed azimuth given by paraboloid

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Time ResidualTime Residual =

(Observed time – expected time)

given Cherenkov cone and track

Remember, simulation LC window at 500 ns instead of 1000ns

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Time Residual at two depths

DomID 5 ~1600m DomID 45 ~ 2300m

Keep in mind, there is an LC time window problem after 500 ns

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Ndir - triggerDirect hit time window:

-15 ns <residual time <+75 ns

1 hit per DOM (first hits)

Difficult to hope for agreement without agreement in Nchan

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Ndir – hard cutsHard cuts = Sigma<3, Ndir>9

Direct hit time window:

-15 ns <residual time <+75 ns

1 hit per DOM (first hits)

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Ldir - triggerLength of direct hits along track

μ

Ldir

Good agreement, but not ideal for IC9 since the detector is asymmetric

Direct hit

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Ldir – hard cutsHard cuts = Sigma<3, Ndir>9

Length of direct hits along track

μ

Ldir

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Paraboloid Sigma - triggerParaboloid samples the likelihood space around the track and fits it to a paraboloid. Sigma is the circularized width of this paraboloid.

θ,φ

L Sigma

There have since been further improvements in paraboloid for higher efficiency

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Paraboloid Sigma – hard cuts

Hard cuts = Sigma<3, Ndir>9

θ,φ

L Sigma

Paraboloid samples the likelihood space around the track and fits it to a paraboloid. Sigma is the circularized width of this paraboloid.

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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