!B_perp   tail/peak 
 0.0105     0.0817
-0.0252     0.0616
-0.0509     0.0493
-0.0766     0.0389
-0.1023     0.0305
-0.1280     0.0238
-0.1537     0.0190
-0.1793     0.0157

-0.2207     0.0157
-0.2463     0.0190
-0.2720     0.0238
-0.2977     0.0305
-0.3234     0.0389
-0.3491     0.0493
-0.3748     0.0616
-0.4105     0.0817