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SPICE Mie [mi:]. Dmitry Chirkin, UW Madison. Updates to ppc and spice. PPC: Randomized the simulation based on system time (with us resolution) Added the implementation of the simple approximate Mie scattering function

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spice mie mi
SPICE Mie [mi:]

Dmitry Chirkin, UW Madison

updates to ppc and spice
Updates to ppc and spice
  • PPC:
  • Randomized the simulation based on system time (with us resolution)
  • Added the implementation of the simple approximate Mie scattering function
  • New oversized DOM treatment (designed for minimum bias compared to oversize=1):
    • oversize only in direction perpendicular to the photon
    •  time needed to reach the nominal (non-oversized) DOM surface is added
    • re-use the photon after it hits a DOM and ensure the causality in the flasher simulation
  • Spice:
  • Fixed code determining the closest DOMs to the current layer (when using tilted ice)
  • Perform simultaneous global fit for py, time offset, scattering vs. absorption correlation coeff.
  • Optimize use of high-event flasher simulation: use 250-event simulation in the dust peak, 10 elsewhere. Eventually use 250-event simulation for the entire depth range.

nominal DOM

oversized DOM

oversized ~ 5 times


timing of oversized dom mc
Timing of oversized DOM MC



 64-48

Flashing 63-50  63-48



do not track back to detected DOM

do not track after detection

no ovesize delta correction!

do not check causality



 64-52

simplified mie scattering
Simplified Mie Scattering

Also known as the Liu scattering function

Introduced by Jon Miller

Single radius particles, described better as smaller angles by SAM

dependence on g cos q and f sam
Dependence on g=<cos(q)> and fSAM

g=<cos(q)> fSAM

0.8 0

0.9 0

0.95 0

0.9 0.3

0.9 0.5

0.9 1.0

flashing 63-50  64-50

new global fit to everything in spice
New global fit to everything in SPICE

1. For some starting values, find best values of lsca ~ labs.

2. Find best values of py, toff, fSAM, asca, aabs, llhtot, …

py photon yield factor

toff global time offset (rising edge of the flasher pulse)

fSAM fraction of SAM contribution to the scattering function

asca scaling of scattering coefficient

aabs scaling of absorption coefficient

3. Repeat until converged (~3 iterations)

4. Refine the fit with lsca and labs independent from each other

Charge only

Full likelihood with timing

verification with toy simulation
Verification with toy simulation

Input table


60 x 250 events

Reconstructed table

with 10 event/flasher

250 event/flasher

In the dust peak

correlation with dust logger
Correlation with dust logger

With 10 events/flasher, 250 in dust peak

With 250 events/flasher everywhere

plots for individual flashers
Plots for individual flashers



plots for corsika data
Plots for CORSIKA/data

 SPICE Mie 

 AHA 

unresolved systematics resolved
“unresolved” systematics: resolved

Minimum is in the same place with both likelihoods!

  • SPICE Mie is great
    •  fits timing perfectly!
  • SPICE paper is available (v. 0.01)
    •  please comment