Etude et impact du bruit de fond corrélé pour la mesure de l'angle ...

152 5. Correlated background
tel-00821629, version 1 - 11 May 2013
Figure 5.31: Correlated background spectrum obtained by combing FN and
SM spectra. The linear fit provides a positive slope of (1.3 ± 1.4)/(3 MeV) 2
and a
2 /dof =4.9/8. The total correlated background rate is found to be
(0.93 ± 0.26) cpd.
tion of the high energy spectral shape to the low energy introduce a bias.
With the analysis developed in this chapter, the obtained pure sample of
correlated background allow to infer directly the FN and the SM spectral
shape at low energy, without any assumption.
An independent analysis has been performed taking advantage from the
muon tagging capability of the OV in Sec. 5.3. The tagged spectra for
both FN and SM are well described by a linear model. The linear fit to
the FN spectra provides a positive slope of (0.17 ± 0.08)/(3 MeV) 2 with
2 /dof = 12.6/8, while the linear fit to the SM spectra provides a negative
slope of ( 0.14 ± 0.14)/(3 MeV) 2 with 2 /dof = 11.3/8. Background
rates of (0.44 ± 0.14) cpd and (0.48 ± 0.11) cpd are found for FN and SM
respectively. The OVT results are found in agreement with the independent
results obtained from the IVT and the SM analysis developed in this
chapter. The background rates obtained so far with three di↵erent analysis,
performed without the OVV, are summarised in Tab. 5.17.