Used file for the fit: SDD_normalized-Efficiency_point-source_with-air_all-levels.csv

parameters
offset a	slope b
-1.375e-06	7.90212e-05

Covariance matrix
1.421e-14	-6.02415e-13
-6.02415e-13	2.59291e-11

used data points for fitting
energy [keV]	efficiency	efficiency error	nuclide
53.15	1.77229e-06	8.57611e-08	Ba133
80.97	4.21605e-07	1.48481e-08	Ba133
