Rotations Around the Longitudinal Axis

label:SROT,TYPE=string,APERTURE=real-vector,ANGLE=real;

The element SROT rotates the reference system about the longitudinal ($s$) axis. SROT has no effect on the beam, but it causes the beam to be referred to the new coordinate system

$$\begin{array}{lcl} x_2&=&x_1\cos\psi-y_1\sin\psi, \\ y_2&=&x_1\sin\psi+y_1\cos\psi, \end{array}$$

It has one real attribute:

ANGLE

The rotation angle psi (default: 0 rad)

A positive angle means that the new reference system is rotated clockwise about the $s$-axis with respect to the old system.

Example:

ROLL1:SROT,ANGLE=PI/2.;
ROLL2:SROT,ANGLE=-PI/2.;
HBEND:SBEND,L=6.0,ANGLE=0.01;
VBEND:LINE=(ROLL1,HBEND,ROLL2);

The above is a way to represent a bend down in the vertical plane, it could be defined more simply by

VBEND:SBEND,L=6.0,K0S=-0.01/6.0;