US 6,639,210 B2 · Geometrically optimized fast neutron detector

Abstract

An improved fast neutron detector fabricated with alternating layers of hydrogenous, optically transparent, non scintillating material and scintillating material. Fast neutrons interact with the hydrogenous material generating recoil protons. The recoil protons enter the scintillating material resulting in scintillations. The detector is optically coupled to a photomultiplier tube which generates electrical pulses proportional in amplitude to the intensity of the scintillations, and therefore are an indication of the energy of the fast neutrons impinging upon the detector. Alternating layers of materials are dimensioned to optimize total efficiency of the detector, or to optimize the spectroscopy efficiency of the detector. The scintillating material is preferably ZnS, and the hydrogenous material is preferably plastic. The detector is ideally suited for well logging applications and fast neutron monitor applications.

Claims25

Dependent claims

A logging tool for measuring a property of material penetrated by a borehole, comprising:

(a) a nuclear radiation detector comprising alternating components of scintillating material and non scintillating, hydrogenous, optically transparent material, wherein said components are fabricated to optimize detector response;
(b) means cooperative with said detector to generate a signal indicative of radiation impinging upon said detector;
and
(c) means for transforming said signal into a measure of said property;
wherein
(d) geometric configuration and dimensions of said components are selected to optimize detector spectroscopy efficiency response.

3 more elements

A method for measuring at least one parameter of material in an environs of a borehole penetrating earth formation, the method comprising:

(a) irradiating said material with pulses of high energy neutrons produced by a neutron generator;
(b) measuring fast neutrons resulting from interaction of said high energy neutrons with said material using a geometrically optimized ZnS/plastic fast neutron detector;
(c) using said measure of fast neutrons in determining said parameter of said material;
(d) measuring prompt gamma radiation resulting from inelastic scatter of said high energy neutrons within said material and combining with said measure of fast neutrons in determining said parameter of said material;
(e) providing a first axially spaced gamma ray detector within said borehole at a first spacing from said neutron generator and providing a second axially spaced gamma ray detector at a second spacing from said neutron generator;
(f) measuring said prompt gamma radiation at said first and said second spacings with said gamma ray detectors;
(g) axially spacing within said borehole said geometrically optimized ZnS/plastic fast neutron detector at a third spacing from said neutron source;
and
(h) measuring said fast neutrons at said third spacing with said geometrically optimized ZnS/plastic fast neutron detector;
wherein;
(i) said gamma ray measurements and said fast neutron measurements at a high energy level and a low energy level are made during said neutron pulses.

8 more elements

Dependencies are inferred from the claim text.

Geometrically optimized fast neutron detector

Life of this patent

Geometrically optimized fast neutron detector

Life of this patent

Abstract

Claims25