An alpha magnet implemented as a matrix, up to 3rd order.
Parallel capable? : yes
GPU capable? : yes
Backtracking capable? : no
Parameter Name  Units  Type  Default  Description 
XMAX  M  double  0.0  size of alpha 
XS1  M  double  0.0  inner scraper position relative to XMAX 
XS2  M  double  0.0  outer scraper position relative to XMAX 
DP1  double  1  inner scraper fractional momentum deviation 

DP2  double  1  outer scraper fractional momentum deviation 

XPUCK  M  double  1  position of scraper puck 
WIDTHPUCK  M  double  0.0  size of scraper puck 
DX  M  double  0.0  misalignment 
DY  M  double  0.0  misalignment 
DZ  M  double  0.0  misalignment 
TILT  double  0.0  rotation about incoming longitudinal axis 

PART  short  0  0=full, 1=first half, 2=second half 

ORDER  short  0  matrix order [1,3] 

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 matrixbased implementation of an alpha magnet [5]. Matrices up to third order are available [4].
The parameter XMAX determines the size of the alpha, which is related to the gradient g in the magnet and the central momentum βγ by
 (26) 
The path length of the central particle is 2.554x_{max}.
Because an alpha magnet has large dispersion at the midplane, it is often used for momentum filtration in addition to bunch compression. The dispersion at the center is given by the simple relation
 (27) 
To use an alpha magnet for momentum filtration in elegant, one must split the alpha magnet into two pieces. One may then either use the scraper features of the ALPH element or other elements such as SCRAPER or RCOL.
To split an alpha magnet, one uses the PART parameter. E.g.,
As just illustrated, the parameters DP1 and DP2 may be used to filter the momentum by providing fractional momentum deviation limits. These are implemented in a physical fashion by computing the corresopnding horizontal position deviations and imposing these as limits on the particle coordinates. One may also do this directly using the XS1 and XS2 parameters, which specify maximum acceptable deviations from the nominal horizontal position. XS1 is the allowed deviation on the lowenergy side while XS2 is the allowed deviation on the highenergy side.
APCONTOUR