¹⁰B+ZnS(Ag) as an alternative to ³He-based detectors for Radiation Portal Monitors

Abstract

Abstract. Typical radiation portal monitor systems, RPM, deployed to detect illicit trafficking of radioactive materials include a set of gamma-ray detectors and neutron detectors. Measurements and models were made, and both detectors were compared. The importance of the distance with respect to the ground was studied. The response with a 252 Cf moderated neutron source (0.5 cm lead and 2.5 cm polyethylene) was calculated in order to compare with other studied alternatives in the USA by Pacific National Northwest Laboratory, PNNL. With these results we conclude that neutron detectors using 10 B+ZnS(Ag) are an interesting alternative for replacing 3 He detectors. From the analysis with MCNPX we propose an improvement in the detector design.

Performance of 10B+ZnS(Ag) neutron detectors in RPM for the detection of special nuclear materials

“…The response increases significantly in efficiency for both detectors when calculation is based on the PNNL neutron source 252 Cf PNNL con figuration. This is probably due to the larger moderation of the source that increases the thermal neutron flux, thus obtaining a better effi ciency than reported from the sources used in the UPM (Guzman Garcia et al, 2017).…”

“…Based on the characteristics of N 15 and N 48 neutron detectors (Guzman Garcia et al, 2016a,b) two new prototype neutron detectors, called N 15 plus and N 48 plus, were studied. In these detectors, the PMMA thickness was increased from 0.635 to 0.800 cm (Guzman Garcia et al, 2016c, 2016d and the 10 B content in the sensitive area was increased to 30% more than N 15 and N 48. The internal config uration can be seen in Fig.…”

“…8 (Kouzes et al, 2010). Table 1 gives the efficiencies modeled for each RPM described above, for a moderated neutron source 252 Cf PNNL , to 200 cm in the exterior (Guzman Garcia et al, 2017). That is, the contribution by the "room return" effect is only attributed to the floor.…”

“…with dimensions 200 × 40 × 15 cm and 5 cm thickness. Each detector had a moderator of 24 + 36+48 mm HDPE, the first detector (N 15C) was positioned 75 cm from the midpoint of the detector with respect to the ground(Guzman Garcia et al, 2016c).N-48 and N-48 plus (RPM): Another model was made using the N 48 detector and modeled together with a PVT gamma detector with dimensions 190 × 41 × 5 cm, both were defined next to each other(Fig. 5), and they were placed inside an iron structure with dimensions 235 × 80 × 18 cm.…”

DEVELOPMENT OF AN MCNP MODEL OF A BORON-10 ZINC SULFIDE SILVER-ACTIVATED [ 10 B/ZnS(Ag)] DETECTOR AND DIRECTIONAL SHIELDING USING RADIATION COUNTING

“…While the surface density of the boron-10 was specified to be 1.8 mg/cm 2 , the exact thickness of the detecting layer was not specified. A thickness of 0.17 cm was assumed based on the detecting elements found in other types of neutron scintillation detectors [4]. Information from the manufacturer of the detector implied the existence of an additional moderator between the boron detecting layer and the casing, and we chose this to be Lucite, the same material that composes the light guide.…”