Samvel Ter-Antonyan and Ali Fazely for ICECUBE,  SUPERNOVA GROUP
Southern University, Baton Rouge

samvel_terantonyan@subr.edu




  • Response I:
    Comments I to the IceCube Internal Report: "Study of SN alarms ...", University of Mainz 201107001

  • Response II:
    Comments II to the IceCube Internal Report: 201107001 (Discussion about DOM noise rate correlations)

  • A.R. Fazely, R.M. Gunasingha., R.L. Imlay, K.D. Muhammad, S.V. Ter-Antonyan, and X. Xu Search capability for $\eta\rightarrow\nu_{e,\tau},\bar{\nu}_{e,\tau}$ decays in cubic-kilometer neutrino detectors, Phys. Rev. D 81, iss 11, 117101 (2010)/ available from arXiv:0902.3451 [hep-ex]
  • Background muon intensity computations.
  • DOM noise rate simulating FORTRAN code (sign_sim_mu) taking into account background muon contribution.
    Results are presented in Response II and Fig.1 below.
  • The simplest twin-DOM noise rate simulating FORTRAN code (Pair_DOMs) for variable muon rates.
    Correlations between total noise rates of two DOMs versus muon noise rate are presented in Fig.3 below.


Figures for discussion

Figure 1. Simulated and detected muon hit distributions.
Mainz data (dashed line, Uppsala report, 2011) disagrees with ICECUBE data and Simulated data (solid lines).

Figure 2. Simulated scatter plots for parameter of Significance and Noise rate per DOM (upper panels).
Corresponding significance distributions are shown in the lower panel. The significance distribution is
in agreement with data presented in Response II and is in strong disagreement with Mainz results.

Figure 3.  Twin-DOM simulator.    Expected 2-DOM correlation coefficients (symbols, upper panel), and RMS of significance distribution (lower panel) versus background muon hit rate (lower panel).

Outlook:

  • Correlation coefficients (upper panel) is in agreement with data from Response II.
  • Broadening of significance distribution for twin DOMs (1.03 for average muon hits ~16 Hz) also is in agreement with 5100 DOM configuration of ICECUBE Response II.
  • This results exactly show that muon contribution to the SN trigger rate is negligible and trigger condition slightly depends on number of DOMs.
  • Lutz Kopke effect i.e. the background muon flux is a source of correlating DOMs, does exists. The values of RMS of significance (Fig.3, lower panel) are exactly equal to (1+rho)1/2 for two DOMs, where "rho" is correlation coefficient (Fig.3, upper panel). However, broadening of significance is small and doesn't describe the observed increase in SN trigger rate (100-200%) for 2008-2011.
  • The expected values of correlation coefficients (Response II, Figure 3) point out to inconsistency of expressions (19,20) from manuscript "Significance with correlated measurements" of Mainz group.
  •   ?
  • Last Mainz data discussion.

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Last update 11.09.11