Method and apparatus for detection of copper

Claim 2

A method as claimed in claim 2 wherein the neutrons are provided by a source having an intensity of at least 108 n/s.

Claim 3

A method as claimed in claim 2 wherein the body is irradiated for at least about 20 minutes.

Claim 4

A method as claimed in claim 2 wherein following irradiation, detection and measurement of the said gamma radiation is delayed for about 10 minutes to allow the decay of interfering isotopes to a lower level of activity.

Claim 5

A method as claimed in claim 2 wherein detection and measurement of the 0.511 MeV peak is carried out by determining the energy spectrum of the gamma radiation, selecting and measuring the 0.511 MeV peak in the spectrum after subtracting the background spectral continuum from said peak, to give a net value for the height of the peak which is a function of total copper present in the body.

Claim 6

A method as claimed in claim 6, wherein the energy spectrum is determined by producing electrical pulses having amplitudes related to the energy of the gamma rays detected, segregating said pulses into channels according to the energies of the corresponding gamma rays, and accumulating a count of the number of pulses in the channel corresponding to 0.511 MeV gamma rays and subtracting from said count the calculated accumulated number of counts attributable to the background spectral continuum.

Claim 8

Apparatus for the detection and estimation of copper in an ore body which comprises means for detecting and measuring the 0.511 MeV peak in gamma radiation emitted from the body due to the annihilation of positrons emitted by Cu62 therein including a radiation detector, said radiation detector comprising detection means for detecting gamma radiation, first shielding means surrounding said detection means for producing a gamma radiation flux when exposed to a thermal neutron flux and second shielding means surrounding said first shielding means for effecting attenuation of the neutron flux reaching said first shielding means wherein the first shielding means comprises 20 to 100 mgm/cm2 of commercial grade (about 95 percent B10 and the second shielding means comprises 10 to 50 mgm/cm2 of lithium carbonate in which about 95 percent of the lithium is Li6.

Claim 9

Apparatus for the detection and estimation of copper in an ore body which comprises means for detecting and measuring the 0.511 MeV peak in gamma radiation emitted from the body due to the annihilation of positrons emitted by Cu62 therein including a radiation detector, said radiation detector comprising detection means for detecting gamma radiation, first shielding means surrounding said detection means for producing a gamma radiation flux when exposed to a thermal neutron flux and second shielding means surrounding said first shielding means for effecting attenuAtion of the neutron flux reaching said first shielding means wherein the second shielding means is partly surrounded by a third shielding means containing a further shielding material which produces a gamma radiation flux when exposed to thermal neutrons.

Claim 10

Apparatus as claimed in claim 10, wherein the said further shielding material is or contains B10, Sm,Gd or Er.

Claim 11

A radiation detector, comprising detection means for detecting gamma radiation, first shielding means surrounding said detection means comprising 20 to 100 mgm/cm2 of commercial grade B10 for producing a gamma radiation flux when exposed to a thermal neutron flux, second shielding means surrounding said first shielding means comprising 10 to 50 mgm/cm2 of lithium carbonate in which about 95 percent of the lithium is Li6 for effecting attenuation of the neutron flux reaching said first shielding means.

Claim 12

A detector as claimed in claim 12, wherein the second shielding means is partly surrounded by a third shielding means containing a further shielding material which produces a gamma radiation flux when exposed to thermal neutrons.

Claim 13

A detector as claimed in claim 13, wherein the said further shielding material is or contains B10, Sm Gd or Er.

Claim 14

A detector as claimed in claim 12, wherein the shields each consist of a coating of a synthetic resin or plastics material containing the shielding substance.