ZGOUBI USERS' GUIDE - HEP

100 4 DESCRIPTION OF THE AVAILABLE PROCEDURES""qMAP2D: 2-D Cartesian uniform mesh field map - arbitrary magnetic field [24]MAP2D reads a 2-D field map that provides the three components , , of the magnetic field at all nodes of a¡åŽ ¡plane. No particular symmetry is assumed, which allows the treatment of any• ¡ – §#"k2-D Cartesian uniform mesh in antype of field (e.g., dipole field with arbitrary elevation - the map needs not be a mid-plane map, solenoidal field, etc.).The data file should be filed with a format that fits the following FORTRAN reading sequence (presumably compatiblewith TOSCA code outputs)OPEN (UNIT = NL, FILE = FNAME, STATUS = ‘OLD’ [,FORM=’UNFORMATTED’])DO 1 J=1,JYDO 1 I=1,IXIF (BINARY) THENREAD(NL) Y(J), Z(1), X(I), BY(I,J), BZ(I,J), BX(I,J)ELSEREAD(NL,100) Y(J), Z(1), X(I), BY(I,J), BZ(I,J), BX(I,J)100 FORMAT (1X, 6E11.4)ENDIF1 CONTINUE{where ¤§ (is the considered-elevation of the map. For binary files, FNAME must begin with ‘B ’ or ‘b ’, a flag ‘BINARY’ will thus be set to‘.TRUE.’. The field ¡) is the number of longitudinal (transverse horizontal) nodes of the 2-D uniform mesh, • is next normalized with BNORM, prior to ray-tracing. As well the coordinates¡X, Y are normalized with X-,Y-NORM coefficients (usefull to convert to centimeters, the working units in zgoubi . ¡ Ž¡|–At each step of the trajectory of a particle, the field and its derivatives are calculated by a polynomial interpolation followedby a extrapolation (see sections 1.3.3, 1.4.3). Entrance and/or exit integration boundaries may be defined, in the sameway as for CARTEMES.