A canonicallyintegrated straight dipole magnet, assumed to have multipoles defined in Cartesian
coordinates.
Parallel capable? : yes
GPU capable? : no
Backtracking capable? : yes
Parameter Name  Units  Type  Default  Description 
L  M  double  0.0  arc length (not chord length!) 
ANGLE  RAD  double  0.0  bend angle 
K1  1∕M^{2}  double  0.0  geometric quadrupole strength 
K2  1∕M^{3}  double  0.0  geometric sextupole strength 
K3  1∕M^{4}  double  0.0  geometric octupole strength 
K4  1∕M^{5}  double  0.0  geometric decapole strength 
K5  1∕M^{6}  double  0.0  geometric 12pole strength 
K6  1∕M^{7}  double  0.0  geometric 14pole strength 
K7  1∕M^{8}  double  0.0  geometric 16pole strength 
K8  1∕M^{9}  double  0.0  geometric 18pole strength 
TILT  RAD  double  0.0  rotation about incoming longitudinal axis 
YAW  RAD  double  0.0  rotation about vertical axis through entrance point 
FRINGEMODEL  long  0  fringe model to use 

HGAP  M  double  0.0  halfgap between poles 
FINT1  double  0.0  edge integral for entrance 

FINT2  double  0.0  edge integral for exit 

FRINGE1K0  double  0.0  Lindberg’s K0 edge integral for entrance 

FRINGE1I0  double  0.0  Lindberg’s I0 edge integral for entrance 

FRINGE1K2  double  0.0  Lindberg’s K2 edge integral for entrance 

FRINGE1I1  double  0.0  Lindberg’s I1 edge integral for entrance 

FRINGE1K4  double  0.0  Lindberg’s K4 edge integral for entrance 

FRINGE1K5  double  0.0  Lindberg’s K5 edge integral for entrance 

FRINGE1K6  double  0.0  Lindberg’s K6 edge integral for entrance 

FRINGE1K7  double  0.0  Lindberg’s K7 edge integral for entrance 

CCBEND continued
A canonicallyintegrated straight dipole magnet, assumed to have multipoles defined in Cartesian coordinates.
Parameter Name  Units  Type  Default  Description 
FRINGE2K0  double  0.0  Lindberg’s K0 edge integral for entrance 

FRINGE2I0  double  0.0  Lindberg’s I0 edge integral for exit 

FRINGE2K2  double  0.0  Lindberg’s K2 edge integral for exit 

FRINGE2I1  double  0.0  Lindberg’s I1 edge integral for exit 

FRINGE2K4  double  0.0  Lindberg’s K4 edge integral for exit 

FRINGE2K5  double  0.0  Lindberg’s K5 edge integral for exit 

FRINGE2K6  double  0.0  Lindberg’s K6 edge integral for exit 

FRINGE2K7  double  0.0  Lindberg’s K7 edge integral for exit 

DX  M  double  0.0  misalignment 
DY  M  double  0.0  misalignment 
DZ  M  double  0.0  misalignment 
ETILT  RAD  double  0.0  misalignment rotation about longitudinal axis 
EPITCH  RAD  double  0.0  misalignment rotation about vertical axis. Ignored if MALIGN_METHOD=0 
EYAW  RAD  double  0.0  misalignment rotation about horizontal axis. Ignored if MALIGN_METHOD=0 
MALIGN_METHOD  short  0  0=original, 1=new entracecentered, 2=new bodycentered 

FSE  double  0.0  fractional strength error 

FSE_DIPOLE  double  0.0  fractional strength error of dipole component 

FSE_QUADRUPOLE  double  0.0  fractional strength error of quadrupole component 

XKICK  RAD  double  0.0  horizontal steering angle (approximate) 
CCBEND continued
A canonicallyintegrated straight dipole magnet, assumed to have multipoles defined in Cartesian coordinates.
Parameter Name  Units  Type  Default  Description 
N_SLICES  long  4  Number of slices (full integrator steps). 

N_KICKS  long  4  number of kicks. Deprecated. Use N_SLICES. 

INTEGRATION_ORDER  short  4  integration order (2, 4, or 6) 

SYSTEMATIC_MULTIPOLES  STRING  NULL  input file for systematic multipoles 

EDGE_MULTIPOLES  STRING  NULL  input file for systematic entrance/exit edge multipoles 

EDGE1_MULTIPOLES  STRING  NULL  input file for systematic entrance edge multipoles. Overrides EDGE_MULTIPOLES. 

EDGE2_MULTIPOLES  STRING  NULL  input file for systematic exit edge multipoles. Overrides EDGE_MULTIPOLES. 

RANDOM_MULTIPOLES  STRING  NULL  input file for random multipoles 

SYSTEMATIC_MULTIPOLE_FACTOR  double  1  Factor by which to multiply systematic and edge multipoles 

RANDOM_MULTIPOLE_FACTOR  double  1  Factor by which to multiply random multipoles 

REFERENCE_ORDER  short  0  Reference order for multipole errors. Overridden by value in multipole files, if those are given. 

MIN_NORMAL_ORDER  short  1  If nonnegative, minimum order of systematic and random normal multipoles to use from data files. 

MIN_SKEW_ORDER  short  1  If nonnegative, minimum order of systematic and random skew multipoles to use from data files. 

MAX_NORMAL_ORDER  short  1  If nonnegative, maximum order of systematic and random normal multipoles to use from data files. 

CCBEND continued
A canonicallyintegrated straight dipole magnet, assumed to have multipoles defined in Cartesian coordinates.
Parameter Name  Units  Type  Default  Description 
MAX_SKEW_ORDER  short  1  If nonnegative, maximum order of systematic and random skew multipoles to use from data files. 

SYNCH_RAD  short  0  include classical, singleparticle synchrotron radiation? 

ISR  short  0  include incoherent synchrotron radiation (quantum excitation)? 

ISR1PART  short  1  Include ISR for singleparticle beam only if ISR=1 and ISR1PART=1 

USE_RAD_DIST  short  0  If nonzero, overrides SYNCH_RAD and ISR, causing simulation of radiation from distributions, optionally including opening angle. 

ADD_OPENING_ANGLE  short  1  If nonzero, radiation opening angle effects are added if USE_RAD_DIST is nonzero. 

SR_IN_ORDINARY_MATRIX  short  0  If nonzero, the (trackingbased) matrix used for routine computations includes classical synchrotron radiation if SYNCH_RAD=1. 

OPTIMIZE_FSE  short  1  Optimize strength (FSE) to obtain the ideal deflection angle. 

OPTIMIZE_DX  short  1  Optimize x offset to obtain centered trajectory. 

OPTIMIZE_FSE_ONCE  short  0  If nonzero, the FSE offset is optimized only once, even if relevant parameters are changed. 

OPTIMIZE_DX_ONCE  short  0  If nonzero, the x offset is optimized only once, even if relevant parameters are changed. 

CCBEND continued
A canonicallyintegrated straight dipole magnet, assumed to have multipoles defined in Cartesian coordinates.
Parameter Name  Units  Type  Default  Description 
COMPENSATE_KN  short  0  If nonzero, K1 and K2 strengths are adjusted to compensate for the changes in FSE needed to center the trajectory. 

REFERENCE_CORRECTION  short  1  1: correct pathlength, 2: correct trajectory, 3: correct both. 

EDGE_ORDER  short  3  Gives order of edge effects. Does not affect edge multipoles. 

DX_DY_SIGN  short  1  Prior to 2020.4, the sign of DX and DY was reversed for ANGLE<0. For backward compatibility, this is retained. Set this field to a positive value to use a consistent convention. 

VERBOSE  short  0  If nonzero, print messages showing optimized FSE and x offset. 

GROUP  string  NULL  Optionally used to assign an element to a group, with a userdefined name. Group names will appear in the parameter output file in the column ElementGroup 

This element provides a symplectic straightpole, bending magnet with the exact Hamiltonian in Cartesian coordinates [61]. The quadrupole, sextupole, and other multipole terms are defined in Cartesian coordinates. The magnet at present is restricted to having rectangular ends. This is quite different from CSBEND, where the edge angles are userdefined and where the field expansion is in curvilinear coordinates. Strictly speaking, CSBEND is only valid when the dipole is built with curved, beamfollowing poles.
Integration of particles in CCBEND is very similar to what’s done for KQUAD, KSEXT, and KOCT. The only real difference is that coordinate transformations are performed at the entrance and exit to orient the incoming central trajectory to the straight magnet axis. In addition, the fractional strength error is adjusted to ensure that the outgoing central trajectory is correct.
By default, two adjustments are made at startup and whenever the length, angle, gradient, or sextupole term change:
One can block the reoptimization of these parameters by setting OPTIMIZE_FSE_ONCE and OPTIMIZE_DX_ONCE to 1. Note also that the optimization is performed with all errordefining parameters (DX, DY, DZ, FSE, ETILT, etc.) set to zero. However, errors that are assigned to, say, the K1 value directly would not be recognized as such. For this reason, assigning errors to K1 is not recommended; instead, use the FSE_QUADRUPOLE parameter.
Having computed the ideal trajectory through a CCBEND element, elegant can suppress any errors in the trajectory. Such errors may occur due to limited accuracy in numerical integration. It is recommended to set REFERENCE_CORRECTION=1 to ensure that the path length is corrected. Optionally, setting REFERENCE_CORRECTION=2 would instead correct residual transverse trajectory errors. Using REFERENCE_CORRECTION=3 corrects both types of error.
Edge angles and edge effects
The user may specify edge multipoles using the EDGE_MULTIPOLE parameter. In addition, the CCBEND element supports two fringe models, selected via the FRINGEMODEL parameter, which may have a value of 0 (default) or 1.
Multipole errors
Multipole errors are specified for the body and edge in the same fashion as for the KQUAD element. The reference is the dipole field by default, but this may be changed using the REFERENCE_ORDER parameter.
Radiation effects
If SYNCH_RAD is nonzero, classical synchrotron radiation is included in tracking. Incoherent synchrotron radiation, when requested with ISR=1, normally uses gaussian distributions for the excitation of the electrons. (To exclude ISR for singleparticle tracking, set ISR1PART=0.) Setting USE_RAD_DIST=1 invokes a more sophisticated algorithm that uses correct statistics for the photon energy and number distributions. In addition, if USE_RAD_DIST=1 one may also set ADD_OPENING_ANGLE=1, which includes the photon angular distribution when computing the effect on the emitting electron.
If SYNCH_RAD and SR_IN_ORDINARY_MATRIX are nonzero, classical synchrotron radiation will be included in the ordinary matrix (e.g., for twiss_output and matrix_output). Symplecticity is not assured, but the results may be interesting nonetheless. A more rigorous approach is to use moments_output. SR_IN_ORDINARY_MATRIX does not affect tracking.
Adding errors
When adding errors, care should be taken to choose the right parameters. The FSE, FSE_DIPOLE, FSE_QUADRUPOLE, ETILT, EPITCH, and YAW, DX, DY, and DZ parameters are used for assigning errors to the strength and alignment relative to the ideal values given by ANGLE and TILT. One can also assign errors to ANGLE and TILT, but this has a different meaning: in this case, one is assigning errors to the survey itself. The reference beam path changes, so there is no orbit/trajectory error. Note that when adding errors to FSE, the error is assumed to come from the power supply, which means that multipole strengths also change.
Assigning errors to K1 is also possible, but is not the best approach, since it changes the internal reference trajectory calculation for the element.
Splitting dipoles
The CCBEND element does not support splitting. Important: Users should not attempt to split CCBEND elements by hand, since this will not result in the correct geometry entering and exiting the various parts.
Matrix generation
elegant will use tracking to determine the transport matrix for CCBEND elements, which is needed for computation of twiss parameters and other operations. This can require some time, so elegant will cache the matrices and reuse them for identical elements.
CENTER