Orienting an underground detector for muon tomography

A system for orienting an underground muon detector, the system comprising:

• at least one muon detector;
• at least one processor;
• a memory storing instructions that, when executed by the at least one processor, cause the at least one processor to perform operations comprising:
• receiving measurements of detected muons from at least one muon detector deployed in a borehole in a subsurface formation;
• generating a measured field of muon detections per steradian over the field of view of the at least one muon detector based on the received measurements;
• generating a null field representing an expected rate of muon detections per steradian over a field of view of the at least one muon detector;
• calculating a misfit parameter between the measured field and the null field;
• aligning the measured field to the null field by minimizing the misfit parameter;
• and
• determining an orientation of the at least one muon detector with respect to a vertical reference and known markers near the at least one muon detector.

One or more non-transitory machine-readable storage devices storing instructions for orienting an underground muon detector, the instructions being executable by one or more processing devices to cause performance of operations comprising:

• receiving measurements of detected muons from at least one muon detector deployed in a borehole in a subsurface formation;
• generating a measured field of muon detections per steradian over the field of view of the at least one muon detector based on the received measurements;
• generating a null field representing an expected rate of muon detections per steradian over a field of view of the at least one muon detector;
• calculating a misfit parameter between the measured field and the null field;
• aligning the measured field to the null field by minimizing the misfit parameter;
• and
• determining an orientation of the at least one muon detector with respect to a vertical reference and known markers near the at least one muon detector.