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

parameters
offset a	slope b
-1.19172e-06	6.82167e-05

Covariance matrix
1.0806e-14	-4.59013e-13
-4.59013e-13	1.9784e-11

used data points for fitting
energy [keV]	efficiency	efficiency error	nuclide
53.15	1.52461e-06	7.49644e-08	Ba133
80.99	3.58568e-07	1.26786e-08	Ba133
