Return the radius of a given plane.
IPLA : number of the plane. MINMAX : 'MIN' or 'MAX' for minimal or maximal radius. TYP : Type of the detector ('TRACKING' or 'CALORIMETER')
From /ZTFWD/ RMN or RMX, min and max radius of detectors; From /ZTFWC/ RMNC or RMXC, min and max radius of detectors; From /ZTGPT/ ROFF, cylinder offset;
none.