Neutron detector using proportional counters

Abstract

A neutron detector module compriging a distribution of proportional counters positioned in in a defined array. Each of the proportional counters includes a supply of a neutron sensitive gas for reacting with neutrons, and this reaction generates ionizing reaction products. The proportional counters include a multitude of tubes, and each of the tubes has a diameter between 0.50 inch and 1.00 inch. The neutron detector module comprises further a multitude of electrical conductors; and each of the conductors is positioned in one of the proportional counters, and the ionizing reaction products generate electric current pulses in the electrical conductors.

1 . A neutron detector module, comprising:
 a container;   a distribution of proportional counters positioned in a defined array in said container, each of the proportional counters including a supply of a neutron sensitive gas for reacting with neutrons, said reacting generating ionizing reaction products, and wherein the proportional counters include a multitude of tubes, each of the tubes having a diameter between 0.50 inch and 1.00 inch; and   a multitude of electrical conductors, each of the conductors extending into one of the proportional counters, wherein said ionizing reaction products generate electric current pulses in the electrical conductors.   
     
     
         2 . The neutron detector module according to  claim 1 , wherein:
 in said defined array, the proportional counters are positioned in a plurality of parallel rows; centers of the parallel rows are spaced apart between about 0.834 and 1.0 inch; and within each of the rows, centers of the proportional counters are spaced apart between about 0.896 and 1.063 inches.   
     
     
         3 . The neutron detector module to  claim 1 , wherein the neutron sensitive gas is BF 3 , and the mass of the BF 3  gas in each of the proportional counters is equal to or less than one gram. 
     
     
         4 . The neutron detector module according to  claim 3 , wherein the pressure in each of the proportional counters is equal to or less than 105 kPa (absolute) at 20° C. 
     
     
         5 . The neutron detector module according to  claim 1 , wherein each of the tubes has a diameter equal to or less than 0.75 inch. 
     
     
         6 . The neutron detector module according to  claim 5 , wherein each of the tubes has a diameter between 0.63 inch and 0.69 inch. 
     
     
         7 . The neutron detector module according to  claim 5 , wherein each of the tubes has a sidewall thickness between 0.015 inch and 0.038 inch. 
     
     
         8 . The neutron detector module according to  claim 1 , wherein said multitude of tubes includes between 22 and 54 tubes. 
     
     
         9 . The neutron detector module according to  claim 1 , further comprising a neutron moderator material inside said container for moderating neutrons in said container, and wherein: the neutron moderator material comprises pellets of the neutron moderator material positioned in the container, around the proportional counters. 
     
     
         10 . The neutron detector according to  claim 1 , further comprising a base neutron moderator material inside said container for moderating neutrons in the container, and wherein: the base neutron moderator material defines a multitude of longitudinal openings; and the proportional counters are held in said longitudinal openings in said defined array. 
     
     
         11 . A method of operating a neutron detector module comprised of a container and a distribution of proportional counters positioned in the container, the method comprising:
 locating the detector module adjacent a source of neutron; and   using the distribution of proportional counters to detect some of the neutrons from said source, each of the proportional counters including a neutron gas for reacting with the neutrons, said reacting generating ionizing reaction products, and wherein the proportional counters include a multitude of tubes, each of the tubes having a diameter between 0.50 inch and 1.00 inch.   
     
     
         12 . The method according to  claim 11 , wherein the neutron sensitive gas is BF 3 , and the mass of the BF 3  gas in each of the proportional counters is equal to or less than one gram. 
     
     
         13 . The method according to  claim 11 , wherein each of the tubes has a diameter between 0.5 inch and 0.75 inch. 
     
     
         14 . The method according to  claim 11 , wherein
 in said defined array, the proportional counters are positioned in a plurality of parallel rows and a plurality of parallel columns;   centers of the parallel rows are spaced apart between about 0.834 and 1.0 inch; and   centers of the columns are spaced apart between about 0.896 and 1.063 inches.   
     
     
         15 . The method according to  claim 11 , wherein beads of neutron moderator material surround the proportional counters in the neutron detector module. 
     
     
         16 . A neutron detector assembly comprising:
 a distribution of proportional counters positioned in a defined array;   at least one support member holding the proportional counters in said defined array;   each of the proportional counters including a supply of a neutron sensitive gas for reacting with neutrons, said reacting generating ionizing reaction products, and wherein the proportional counters include a multitude of tubes, each of the tubes having a diameter between 0.50 inch and 1.00 inch; and   a multitude of electrical conductors, each of the conductors extending into one of the proportional counters, wherein said ionizing reaction products generate electric current pulses in the electrical conductors.   
     
     
         17 . The neutron detector assembly according to  claim 16 , wherein the neutron sensitive gas is BF 3 , and the mass of the BF 3  gas in each of the proportional counters is equal to or less than one gram. 
     
     
         18 . The neutron detector assembly according to  claim 17 , wherein:
 in said defined array, the proportional counters are positioned in a plurality of parallel rows and a plurality of columns;   centers of the parallel rows are spaced apart between about 0.834 and 1.0 inch; and   within each row, centers of the proportional counters are spaced apart between about 0.896 and 1.063 inches.   
     
     
         19 . The neutron detector assembly according to  claim 18 , wherein each of the tubes has a diameter between 0.63 inch and 0.69 inch. 
     
     
         20 . The neutron detector assembly according to  claim 11 , further comprising pellets of neutron moderator material extending around the proportional counters to moderate neutrons in the neutron detector assembly.