Minutes y08m02d06

Present: Aya, Keiichi, Mina, Yuusuke, Shigeru (Chiba)
David, Kotoyo (UW-Madison)
Mio, Spencer (LBNL)
Alex, Bryan, Henrike (Maryland)

(a) The EHE paper draft (Aya)

The draft (version 1.4) have been uploaded in the EHE paper docushare . Several comments from Spencer are :

(1) Mention systematic uncertainties due to the LPM effect and the layered/bulk ice model
(2) Reason why the effective area continues to increase with energy
(3) Suggestion to change the order of the description on IC-9 and IC-80 in the Section 3
because this paper primarily focuses on the analysis method for the IceCube EHE analysis
(4) Show the limits from the other experiments in the IC-80 sensitivity plot.
(5) Mention why the background numbers for IC-80 listed in table III is smaller than
those for IC-8 despite of the larger fiducial volume
(6) Mention why the cases with/without the GZK cut-off list the same single number
on the muon background rate in table I and III
(7) Mention why some "upgoing" signal events exist contributing to the FIG.7.
(This happened because of the geometrical reconstruction error)
(8) Add a brief description about the prompt component.
(We did in the Systematics, and the Summary and Outlook sections - see if they are satisfactory.)
(9) Would be interesting to see any comparison between JULIeT and mmc

Aya includes these comments and the others and submits the new version to the Pub-com in a week.

(b) The starting track filter (Mio)

Her filter aims at identifying events that are background-free from the atmospheric muon backgrounds,
by looking for signatures of neutrino interactions inside the IceCube volume.
The present status was reported.
The proposed algorithm being tested now are based upon existence of DOMs with no hits at very close distances
to the track or the location of COG using first 5 DOMs with photon hits. The very tentative effective
area obtained with this criteria appears a factor of two smaller than the area presently obtained by
the standard EHE event selection criteria. Suggestions are made on using the reconstructed geometry
instead of the MC truth and investigation of the possible dust layer effects.

The filter proposals and the supporting documents are compiled and found here .
The 2008 EHE filter utilizes total NPE instead of NDOMs.
The apparent discrepancy of the expected data rate between the EHE proposal by Aya
and the monopole proposal by Brian arises from the errors in consideration of the NDOM-80 bias.
The EHE and the exotic working groups agreed that :

(1) Increase the NPE threshold to 1000 (or any appropriate numbers) to accommodate the bandwidth
(2) Use the calibration mode 1
(3) No droop correction

Kael (UW-Madison) is in charge of dealing with the EHE filter proposal at
the TFT board. Aya together with Brian responds him to realize the NPE-based high energy filter.

The new MC data with the AHA ice model still exhibits more NPE yield than
the real data extracted by the Aya's filter . The difference is around 35-40 %
regardless of the hole ice model settings. In close looks, she found that the MC indicates
more attenuation/scattering than the real data judging from the waveform shape and
the NPE attenuation length as a function of distance.
It is also remarked that DOMs in the String-40, the Standard Candle string, records less NPE in the MC,
suggesting that the scattering angle settings in the photonics may be a problem.

Kotoyo made similar approaches from aspect of the leading edge time distribution
of the muon data proposing the photonics run with different sets of the scattering mean free
path and the angle that gives the same "effective" scattering coefficient.
She also found serious buggy features in the photonics table reader that may contribute to
the waveform stretching. The way of the table binning, the interpolation, and
sampling the delay time, may be problematic. She contacts Klas on this matter.

(d) IC-22 analysis (Keiichi)

The optimization study of the Corsika muon bundle simulation settings was reported.
Introducing the threshold energy of 1 TeV for muons in a bundle seems a good compromise
for practical processing time to generate MC data. David showed his concern on the possible drawback
due to missing low energy muons. Keiichi updates some plots to clarify the pros and cons.

(e) DOM simulator status (Alex)

DOM simulator had been using the FADC response function ignoring the preamp response
ending up with too narrow waveform shape to be sampled with 25 nsec bins. It induced several
strange behaviors in the simulated data, although simulating high NPE signals that are relevant
to EHE analysis seems less affected by this problem. The new DOM simulator was committed
to trunk, but its slow processing time is a drawback. We will test it to decide which version
of the simulator for the next EHE data generation.

(f) misc

Becase of many overlapping in the data analysis and simulations, both the EHE and the exotic working groups
will have a monthly/bi-monthly phone meeting for close interactions between the two.