Distance and direction-sensitive cosmogenic neutron sensors

A wide area cosmogenic neutron sensor for detecting moisture within a measurement surface, the wide area cosmogenic neutron sensor comprising:

• a neutron detector positionable above the measurement surface, wherein a first moderator material is positioned around only a portion of the neutron detector to form a moderated neutron detector;
• a second moderator material positioned along a bottom of the moderated neutron detector, the second moderator material being separate from the first moderator material;
• a neutron shield positioned along the bottom of the moderated neutron detector, whereby the neutron shield substantially covers an entirety of the bottom of the moderated neutron detector, wherein the neutron shield is positioned to interact with cosmogenic neutrons propagating to the bottom of the moderated neutron detector, thereby substantially blocking fast, epithermal, and thermal cosmogenic neutrons propagating to the bottom of the moderated neutron detector from reaching the moderated neutron detector, and wherein the neutron shield is not positioned on at least a top side of the moderated neutron detector;
• and
• a stand structure holding the moderated neutron detector and the neutron shield in a position a spaced vertical distance above the measurement surface with the bottom side of the moderated neutron detector facing the measurement surface,
• wherein wide area cosmogenic neutrons propagating from the measurement surface travel through an air space before arriving at the moderated neutron detector.

A method for detecting wide area cosmogenic neutrons for use in detecting moisture within a measurement surface, the method comprising the steps of:

• positioning a neutron detector above the measurement surface, wherein a moderator material is positioned around at least a portion of the neutron detector to form a moderated neutron detector;
• placing a neutron shield around a portion of the moderated neutron detector, whereby the neutron shield substantially covers an entirety of a bottom of the moderated neutron detector, whereby the neutron shield is positioned to interact with cosmogenic neutrons propagating to the bottom of the moderated neutron detector, thereby substantially blocking fast, epithermal, and thermal cosmogenic neutrons propagating to the bottom of the moderated neutron detector from reaching the moderated neutron detector, and wherein the neutron shield is not positioned on a top side of the moderated neutron detector;
• and
• spacing the moderated neutron detector a spaced vertical distance about the measurement surface with a stand structure, whereby the bottom side of the moderated neutron detector faces the measurement surface,
• whereby wide area cosmogenic neutrons propagating from the measurement surface travel through an air space before arriving at the moderated neutron detector.