A ratio, {HEAD ~ Ib/Id} increases with {TAIL ~ a magnetic gradient value}, ∂Hr/∂z to 0.8–0.9 
A ratio , { HEAD ~ Ib / Id } increases with { TAIL ~ a magnetic gradient value } , ∂Hr/∂z to 0.8–0.9
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH