south pole ice model
DESCRIPTION
South Pole Ice model. http://icecube.wisc.edu/~dima/work/WISC/ppc/spice/. Dmitry Chirkin, UW, Madison. IceCube in-ice calibration devices. 3 Standard candles 56880 Flashers 7 dust logs. Flasher dataset. Simulation. For muons: folded with Cherenkov spectrum. Flasher 405 nm. - PowerPoint PPT PresentationTRANSCRIPT
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South Pole Ice model
Dmitry Chirkin, UW, Madison
http://icecube.wisc.edu/~dima/work/WISC/ppc/spice/
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IceCube in-ice calibration devices
3 Standard candles56880 Flashers7 dust logs
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Flasher dataset
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Simulation
Fla
sher
405
nm
For
muo
ns:
fold
ed w
ith
Che
renk
ov s
pect
rum
Sample Cherenkov photons from this curve
Angular sensitivity
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Fitting the data
1 event simulated
4 events
10 events
Red: AHABlack: SPICE
• Absolute calibration of average flasher is obtained “for free” no need to know absolute flasher light output beforehand no need to know absolute DOM sensitivity
2.1 3.1
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Likelihood description of data
Find expectations for data and simulation by minimizing –log of
Regularization terms:
Measured in simulation: s and in data: d; ns and nd: number of simulated and data flasher events
Sum over emitters, receivers, time bins in receiver
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Dependence on initial seed
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Including the dust logger data
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Correlation with dust logger dataef
fect
ive
sca
tter
ing
coef
ficie
nt (from Ryan Bay)
Scaling to the location of hole 50
fitted detector region
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Merged data
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Refining the solution
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Refining the solution
7% in a1% in be
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Possible reasons for this discrepancy
• flasher directionality was ignored: cylindrical symmetry of the 6-flasher emission pattern was assumed
checked: simulating flashers with measured directions (6-prong star pattern) reproduces the above result exactly
• effects of the hole ice on photon propagation were taken only through the angular sensitivity curve
however: resulting ice properties are the same (within uncertainties) for either nominal or hole ice angular sensitivity
• various issues in recorded waveforms: effects of saturation and undershoot, miscalibration, etc.
already: using the saturation correction.
• Fine structure of ice layers matters? under investigation
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History of changes11/19/09 SPICE (also known as SPICE1): first version
* seeded with AHA as initial solution * AHA is used for extrapolation above and below the detector * relies on AHA for correlation relation between be(400) and adust(400).
02/01/10 SPICE2:
* fixed the hdh bug (see ppc readme file) * seeded with bulk ice as initial solution * dust logger and EDML data is used for extrapolation * dust logger data is used to extend in x and y, taking into account layer tilt.
02/17/10 SPICE2+:
* fixed the "x*y" option hit counting in ppc * be(400) vs. adust(400) relation is determined with a global fit to arrival time distributions.
04/28/10 SPICE2x (this page):
* improved charge extraction in data:
improved merging of the FADC and ATWD charges implemented saturation correction fixed the alternating ATWD bug
* updated DOM radius 17.8 --> 16.51 cm (cosmetic change: modifies only the meaning of py) * fixed the DOM angular sensitivity curve (removed upturn at cos()=-1).
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SPICE models
py=3.1
py=2.1
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SPICE models
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SPICE models
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SPICE models
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SPICE models vs. AHA
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Ratio to SPICE2x
7% uncertainty 5% uncertainty
py=3.1py=2.1
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Why does AHA not work?
Fits systematically offPoints at same depth not consistent with each other!
Individually fitted for each pair: best possible fit
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Why does AHA not work?
Averaged scattering and absorptionFrom ice paper
Measured properties not consistent with the average!Deconvolving procedure is unaware of this and is using the averages as input
When replaced with the average, the data/simulation agreement will not be as good
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SPICE vs. AHA: horizontal flashers
SPICE
AHA
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SPICE vs. AHA: 45 degree flashers
SPICE
AHA
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Single muons generated with mmc
SPICE
AHA
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Muon bundles generated with corsika
SPICE
AHA
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Nch of flasher events
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Improvement in simulation
by Anne Schukraft by Sean Grullon
Downward-going CORSIKA simulation Up-going muon neutrino simulation
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Unfolded data with only events in the top or bottom
preliminary preliminary
IC-22 atmospheric neutrino analysis
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IC-22 unfolding result
• Despite problems in detector simulation, agreement with Bartol muon neutrino flux was demonstrated
• It was decided that the simulation, namely simulation of the ice, needed improvement before this analysis can proceed to claiming a measurement of the neutrino flux.
• This problem has been solved! redo the analysis (with IC-40)
preliminary
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Conclusions and outlook
1. SPICE (South Pole ICE) model: fitted to IceCube flasher data collected on string 63 demonstrated remarkable correlation with the dust logger data
therefore was extended to incorporate these data (SPICE2) uses flasher timing information (since SPICE2+)
2. Rapid progress in simulation leads to very good agreement with data: In-situ flasher simulation background muon simulation neutrino simulation
3. Uncertainties on the model are ~ 5% on scattering and ~ 7% absorption Need to understand remaining ~ 7% disagreement between timing
and amplitude distributions
4. Future: measure the wavelength dependence with the standard candle