Simultaneously to the first chain, a second chain of amplified signal, based on a cylindrical 3
He central detector of EURYSIS type (0.5NH1/1K1) inside a sphere of 9 in. diameter connected to a
charge amplifier of CANBERRA type (ACHEMS98), was provided to take into account for the power instability of the NUR research reactor during the BSS measurements. Thus, all the recorded BSS
count rates obtained with the first electronic chain were normalized to those of the second one