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Review Committee Meeting Monday 13 November 2006 12:00 Pacific / 15:00 Eastern

Minutes: Monday 13 November 2006 12:00 Pacific / 15:00 Eastern

Agenda and Contact Info

Agenda

  1. GRB Search Review Status
    • Check of population constraints code directory [ HTML ] and exclusion figure [ PDF ]
  2. S4 Untriggered Search Review Status
  3. Other Projects (SGR, LIGO-GEO, Cosmic String)
  4. AOB

Contact Info

AccuConference teleconferencing service:
   Phone: 1-800-704-9896, participant code: 038621#
   International callers ++1-404-920-6472 with same code

Minutes

  1. GRB Search Review Status
    • Injections: should they be done into off-source segments?
      • Discussion about whether injection into off-source segments is correct even in principle. JC maintains that they should be done into off-source segments, Isabel argues they should be done into on-source segments.
      • JC reiterated his concern that a bias can be introduced because data in on-source segment is constrained by observation (i.e., that all cc values are less than or equal to the observed max-cc).
      • Probably the bias would be small but either injections should be done into off-source segments or it needs to be shown that any bias is small.
    • Figs. 3 and 4.
      • Isabel will look at notes on construction of the conf. belt.
    • Population constraints
      • In response to comments at LSC meeting, JC has constructed confidence belts in energy rather than snr as this is a more accesible result [ PDF ].
      • This simulation doesn't use a detailed model of redshift distribution. It uses a simple beta distribution with z^3 at low z, zpeak=1.8, and zmax=25. Would want to get a better redshift distribution part of code.
      • Soumya doesn't like shaded region of belt since exclusion region is one-dimensional.
      • For design sensitivity curve, there is an inconsistency: the value of S_geom(f) is taken to be that of two identical 4k detectors, but the analysis only works with H1 + H2. An H1 L1 analysis is somewhat different. Needs to be made consistent. A coherent analysis would use all three IFOs.
      • Issue about whether to assume a source emitting with quadrupolar emission pattern vs. with an isotropic emission pattern. Need to decide on a convention. Overall factor of 4/5 in Eq. (18).
      • Issue is that factor of eta^-2 must be included in Monte Carlo to obtain these belts: cannot simply multiply limit on snr by the average value of eta^-2 to get an energy bound. If the group wishes to make bounds on snr rather than energy then do not convert a snr limit to an energy bound.
      • Soumya is unhappy about including including this factor in simulation. Doesn't like having a per-GRB random variable (though the distance is a per-GRB random variable in simulations). Would rather keep confidence belt on snr rather than energy.
      • Don't understand why large snr values are discarded: these should not matter. Redo without discarding large snr values.
      • Factor of 2 error in definition of snr in Eq. (17).
      • Should choose to use either eta or Fave, not both.
    • Need to update technical report. Isabel says it will be easier to have an addendum.
  2. S4 Untriggered Search Review Status: substative changes
    • Add comparison to Rome burst search exclusion plot. (Are the figures directly comparible or do they need conversion?)
    • Go one step further from sensitivity in terms of energy to sensitivity in terms of distance to various sources. How much precision needed? Issue is that the actual detection efficiency to specific sources has not been measured, so it will have to be estimated somehow.
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