SPECIFICATION OF BONNER SPHERE SYSTEMS FOR NEUTRON SPECTROMETRY

The response functions of four widely used Bonner sphere spectrometers (BSS) with an LiI scintillator and different He-3 detectors were calc ulated by means of the three-dimensional Monte Carlo neutron transport code, MCNP, taking into consideration a detailed description of the d etector set-up; they were then compared with experimental calibration data. The calculated response functions reproduce the calibration data in shape. A common adjustment factor is only needed to take into acco unt the neutron detection efficiency of the central detector. An inter polation method proposed to correct the BSS response functions to anot her polyethylene density was verified.