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3.3.3 marker

marker has no effect but allows one to identify a position in the beam line (say, where a sampler will be placed). It has no attributes.

Example:

m1 : marker;

3.3.4 drift

drift defines a straight drift space. Attributes:

Example :

d13 : drift, l=0.5*m;

3.3.5 rbend

rbend defines a rectangulat bending magnet. Attributes:

when B is set, this defines a magnet with appropriate field strength and angle is not taken into account. Otherwise, B that corresponds to bending angle angle for a particle in use (defined by the beam command, with appropriate energy and rest mass) is calculated and used in the simulations.

Example :

rb1 : rbend, l=0.5*m, angle = 0.01;

3.3.6 sbend

sbend defines a sector bending magnet. Attributes:

Example :

The meaning of B and angle is the same as for rbend.

rb1 : rbend, l=0.5*m, angle = 0.01;

3.3.7 quadrupole

quadrupole defines a quadrupole. Attributes:

Example :

qf : quadrupole, l=0.5*m , k1 = 0.5 , tilt = 0.01;

3.3.8 sextupole

sextupole defines a sextupole. Attributes:

Example :

sf : sextupole, l=0.5*m , k2 = 0.5 , tilt = 0.01;

3.3.9 octupole

octupole defines an octupole. Attributes:

Example :

sf : octupole, l=0.5*m , k3 = 0.5 , tilt = 0.01;

3.3.10 multipole

will be implemented starting from v0.2

3.3.11 rcol

rcol defines a rectangular collimator

Attributes:

Example :

col1 : rcol,l=0.4*m, xsize=2*mm, ysize=1*mm, material="W"

The longitudinal collimator structure is not taken into account. To do this the user has to describe the collimator with the generic type element

3.3.12 ecol

rcol defines an elliptical collimator

Attributes:

Example :

col2 : ecol,l=0.4*m, xsize=2*mm, ysize=1*mm, material="W"

Here the longitudinal collimator structure is also not taken into account.

3.3.13 solenoid

will be implemented starting from v0.2

3.3.14 transform3d

An arbitrary 3-dimensional transformation of the coordinate system is done by placing a transform3d element in the beamline. The syntax is

Example:

rot : transform3d, psi=pi/2

3.3.15 element

All the elements are in principle examples of a general type element which can represent an arbitrary geometric entity with arbitrary B field maps 1. Its attributes are

Descriptions are of the form

format:filename

where filename is the path to the file with the geometry description and format defines the geometry description format. The possible formats are given in Geometry.

Example :

qq : element, geometry = plain:qq.geom, bmap = plain:qq.bmap;

<bmap> and <emap> are definitions of E and B field maps according to (field maps).

cryomodule.jpg

Figure 3.1: An example of Mokka Geometry

3.3.16 line

elements are grouped into sequences by the line command.

line_name : line=(element1,element2,...);

elementn can be any element or another line.

Example :

A sequence of three FODO cells can be defines as

     
     qf: quadrupole, l=0.5, k1=0.1;
     qd: quadrupole, l=0.5, k1=-0.1;
     d: drift, l=0.5;
     fodo : line=(qf,d,qd,d);
     beamline : line{fodo,fodo,fodo};
     

3.3.17 aperture

3.3.18 material

<material> : material,Z=,A=,density=,temperature=

Attributes

3.3.19 pipe

the beam pipe parameters are used for particle tracking inside elements when the use geometry is not defined. The beam pipe radius is assigned by the pipe command

pipe, range=<range>, range=, r=, thickness=, material=<material>;

Attributes

Example :

Supposing we want to define a copper beam pipe for ...

     iron : material, Z=1,A=1,density=100, temperature=;
     copper : material,Z=,A=,density=,temperature=;;
     
     fodo : line=(qf,d,qd,d);
     pipe, range=qf/qd, r=0.2, thickness = 0.1,material=copper; 
     pipe, range=d[2], r=0.1, thickness = 0.05,material=iron; 
     

3.3.20 laser

laser defines a drift section with a laser beam inside.

<laser_name>: laser, position = {<x>,<y>,<z>},direction={ <dx>, <dy>, <dz> } wavelen=<val>, spotsize=<val>, intensity=<val>;

Attributes

the laser is considered to be the intersection of the laser beaam with the volume of the drift section.

3.3.21 gas

gas command is used to introduce gas into the beam pipe. 2

gas, period=, components={c1,c2,...},parts={p1,p2,...} ;

where

the gas componens are defined by

c1 : gas, name=<name>, A=<A>, Z=<Z>, profile=<profile_name>;

where

the gas profile is defined as

<profile_name> : gas_profile = (<element>:<pressure>, <element>:<pressure>) ;

where

The gas pressure is then interpolated between the points where it is defined. Issuing multiple gas commands acts additively.

Example :

To introduce the gas into a fodo cell

     
     ...element definitions...
     
     fodo : line=(qf,d,qd,d);
     
     co2 : gas, name="c02", Z=22,A=44,profile=co2profile;
     h20 : gas, name="h2", Z=1,A=1,profile=co2profile;
     
     c02profile : gas_profile = (qd:0.01, qf:0.02*nbar,d:0.03*nbar); 
     h20profile : gas_profile = (qd:0.04, qf:0.01*nbar,d:0.03*nbar); 
     
     gas, period=fodo,components= { c02,h20},parts={0.7,0.8}; 
     
     

Footnotes

[1] E fields will be implemented starting from release v0.2

[2] in realistic situations the gas profile can vary in transverse dimensions. This is not taken into account for a)technical reasons b)one does not know the profile anyway