Neutron detection systems with radiation portal monitors
View Patent ↗A neutron detection system comprising a radiation portal monitor is disclosed. The radiation portal monitor includes a neutron moderator sheet and a neutron-sensing panel and is configured to receive incoming neutrons through a neutron collection portal area. The neutron-sensing panel comprises a neutron-sensing material optically coupled to a plurality of optical fibers such that the neutron moderator sheet and the neutron-sensing panel are disposed substantially parallel to the neutron collection portal area.
1. A neutron detection system, comprising:
a radiation portal monitor configured to receive incoming neutrons through a neutron collection portal area and comprising:
a neutron moderator sheet; and
a neutron-sensing panel comprising a plurality of neutron-sensing material filaments optically coupled to a plurality of optical fibers; wherein
the neutron moderator sheet and the neutron-sensing panel are disposed substantially parallel to the neutron collection portal area.
2. The system of claim 1 , wherein the neutron collection portal area is substantially perpendicular to the incoming neutrons from a monitored neutron source.
3. The system of claim 1 , wherein the neutron collection portal area is greater than 0.5 m 2 .
4. The system of claim 1 , wherein the neutron-sensing material comprises a scintillating material.
5. The system of claim 1 , wherein the neutron-sensing material consists essentially of solid materials.
6. The system of claim 1 , wherein the neutron-sensing material comprises 6 Li-enriched lithium fluoride and a mixture of zinc sulfide based phosphor.
7. The system of claim 1 , wherein the neutron-sensing material is disposed in the form of a neutron-sensing sheet.
8. The system of claim 7 , wherein the thickness of the neutron-sensing sheet is less than 1 mm.
9. The system of claim 7 , wherein the plurality of optical fibers are side-coupled to at least one side of the neutron-sensing sheet.
10. The system of claim 1 , wherein the plurality of neutron-sensing material filaments are enclosed by an annular or tubular optical waveguide material.
11. The system of claim 1 , wherein the system further comprises a photo-sensing element optically coupled to the optical fibers and having a finite detection window area.
12. The system of claim 11 , wherein the detection window area of the photo-sensing element is less than 10% of the neutron collection portal area.
13. The system of claim 1 , wherein the neutron detection system is gamma ray insensitive.
14. The system of claim 1 , further comprising wavelength shifting fibers.
15. The system of claim 1 , wherein a surface of the optical fiber is coated with a reflective layer to improve internal reflection.
16. A neutron detection system, comprising:
a radiation portal monitor configured to receive incoming neutrons through a neutron collection portal area and comprising:
a neutron moderator sheet;
a neutron-sensing panel comprising neutron-sensing material filaments enclosed in an annular or tubular optical waveguide material; and
a photo-sensing element optically coupled to the optical waveguide material,
wherein the neutron moderator sheet and the neutron-sensing panel are disposed substantially parallel to the neutron collection portal area.
17. The neutron detection system of claim 16 , wherein a refractive index of the optical waveguide material is greater than that of the neutron-sensing material.