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CHAPTER 9. Experiment definition with AEDL
The choice of the sampling point configuration strongly depends on the experiment
and required accuracy. Ideally the integrand of Eq. 9.9 is zero outside the sampling
range, if this cannot be achieved it is usually sufficient that the sampling range is by
about three times the energy resolution4 larger than the bin range. The spacing of
the sampling points should be somewhat smaller (a factor ' 2 usually is more than
ebough) than the finest details of the integrand.
Bin level This level is determined by the experiment and its analysis. Note that energy
bin sizes much smaller than the energy resolution will not improve the results. The
energy bin range and the number of energy bins do always have to be specified. For
the case of large values of the integrand in Eq. (9.9) at the energy range limits, it is
recommended to exceed the analysis energy window by about three times the energy
calibration error in order to avoid cutoff effects.
In order to define a range between Emin and Emax divided by a certain number of
equidistant bins, use
$emin = 4.0
$emax = 50.0
$bins = 20
For arbitrary bins, use Emin and Emax and the size of each bin ∆Ei :
$emin = 4.0
$emax = 50.0
$binsize = { 15.0 , 5.0 , 20.0, 6.0 }
The number of bins will be automatically computed by GLoBES. Note that the bin
sizes have to add up to the energy range $emax-$emin.
The choices at bin level are mainly determined by optimizing the performance of the
experiment.
Analysis level On the analysis level, an energy window can be defined within each rule.
For details, see next chapter.
In general, the energy smearing happens between the sampling point and bin levels,
which means that the energy smearing matrix will have $sampling_points columns and
$bins rows.
As illustrated in the figure, an interesting feature in combination with the channels are pre- and post-smearing effects.
Pre-smearing effects are taken into account on the sampling point level, and post-smearing effects on the bin level. Examples for these effects are energy dependent efficiencies and (non-beam) backgrounds. Efficiencies are multiplicative factors, whereas backgrounds are added to
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evaluated at $emin and $emax respectively