Energy-sensitive fast neutron imaging detector and method for energy-sensitive fast neutron detection

Patent metadata

Field	Value
Publication number	US-9632189-B2
Application number	US-201314427691-A
Country	US
Kind code	B2
Filing date	Aug 13, 2013
Priority date	Sep 12, 2012
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

An energy-sensitive imaging detector for fast-neutrons includes energy-selective radiator foil stacks converting neutrons into recoil protons. The foils are separated by gas-filled gaps and formed of two interconnected layers: a hydrogen-rich layer such as a polyethylene layer for neutron-to-proton conversion, and a metal foil layer, such as an aluminum layer, defining a proton energy cut-off and limiting a proton emission angle. Energetic recoil protons emerging from the radiator foil release electrons in surrounding gas in the gaps. An electric field efficiently drifts the electrons through the gaps. An electron detector with position sensitive readout, based on Micro-Pattern Gaseous Detector technologies (such as THick Gaseous Electron Multipliers—THGEM) or other measures provides electron amplification in gas. The charge detector has a dedicated imaging data-acquisition system detecting the drifted electrons thereby sensing the position of the original impinging neutrons.

First claim

The invention claimed is:

1. An energy-sensitive neutron imaging detector, comprising:
a) a plurality of energy-selective stacks of radiator foils being penetrable by incident neutrons, said energy-selective stacks being disposed consecutively in a flight direction of the incident neutrons;
b) said radiator foils having a thickness increasing stepwise or continuously in said flight direction of the incident neutrons and including consecutive radiator foils being separated by gas-filled gaps, said radiator foils each including a hydrogen rich radiator layer and an energy-selective coating layer fastened to said hydrogen rich radiator layer, and said increasing thickness of said radiator foils being achieved by an increasing thickness of said energy selective coating layer; and
c) a plurality of position sensitive charge detector structures being associated with at least one of said radiator foils or said gas-filled gaps.

2. The neutron imaging detector according to claim 1 , wherein said energy-selective coating layer is a metallic foil.

3. The neutron imaging detector according to claim 2 , wherein said metallic foil is an aluminum foil.

4. The neutron imaging detector according to claim 1 , wherein said gas-filled gaps separating said consecutive radiator foils ( 6 ) are aligned with said position sensitive charge detector structures.

5. The neutron imaging detector according to claim 1 , wherein each of said energy selective stacks includes a plurality of said radiator foils.

6. The neutron imaging detector according to claim 1 , wherein said thickness of said radiator foils within the same energy selective stack is constant.

7. The neutron imaging detector according to claim 1 , wherein said position sensitive charge detector structures are based on the Thick Gaseous Electron Multiplier principle thereby using Ne gas or a Ne-based gas mixture in said gas-filled gaps.

8. A method for energy-sensitive neutron detection, the method comprising the following steps:
a) providing a plurality of energy-selective stacks of radiator foils being penetrable by incident neutrons, the energy-selective stacks being disposed consecutively in a flight direction of the incident neutrons, the radiator foils having a thickness increasing stepwise or continuously in the flight direction of the incident neutrons and including consecutive radiator foils being separated by gas-filled gaps;
b) providing each of the radiator foils with an energy selective coating layer having proton blocking properties and a hydrogen rich radiation layer having a back side in a direction of an incoming neutron beam, fastening the energy selective coating layer to the back side of the hydrogen rich radiation layer, and achieving the increase in the thickness of the radiator foils by increasing a thickness of the energy selective coatings;
c) providing a plurality of charge detector structures being associated with the radiator foils;
d) penetrating the plurality of energy-selective stacks with neutrons thereby generating protons, the protons generating ionization electrons in the gas-filled gaps;
e) detecting the electrons in the charge detector structures; and
f) determining the energy of the incident neutrons according to a spatial distribution of the detected electrons in the charge detector structures.

9. The method according to claim 8 , which further comprises adjusting the thickness of the hydrogen-rich radiator layers to the thickness of the energy selective coatings in each stack to achieve maximal detection efficiency.

10. The method according to claim 8 , which further comprises orienting the radiator foils substantially perpendicular to a direction of the incident neutrons.

Assignees

• Scherrer Inst Paul
• Physikalisch-Technische Bundesanstalt

Inventors

• Cortesi Marco
• Dagendorf Volker
• Prasser Horst-Michael
• Zboray Robert

Classifications

• G01T3/003 Primary

  Recoil spectrometers (light-nuclei recoil ionisation tubes per se H01J47/1277) · CPC title

• G01T1/185 Primary

  with ionisation chamber arrangements · CPC title

• G01T3/008

  using an ionisation chamber filled with a gas, liquid or solid, e.g. frozen liquid, dielectric (G01T3/006 takes precedence) · CPC title