About Genesis
Input Parameters
Input Files
Getting Started
3rd Party Programs
Input File Library
Other Links

The External Distribution File

GENESIS 1.3 support external phase space distribution, generate by other simulation codes (e.g. ELEGANT). To enable the feature the input parameter DISTFILE points to a file, which contains the particle distribution of the entire bunch.

The format is ASCII and for each particle all 6 coordinates must be supplied per line. Additional information can be added per particle (such as particle ID), which is ignored by GENESIS 1.3 in the current version.

Similar to the beam description file and the magnetic field input file the functionality is extended by additional file information or comments.

Lines starting with the #-sign and empty lines are ignored. The question mark indicates information lines. The VERSION and the SIZE keywords are the same as in the beam description file. Again if the version is smaller than 1.0 and the SIZE keyword is omitted the first line, containing data, must be the size of the following data set. This value is used to check for consistency and completeness of the distribution file. A required information the charge in Coulombs, defined by the CHARGE keyword

The order of the 6 coordinates and additional values is set by the COLUMNS keyword followed by the names of each column in the data set. In the current version the total number of columns is limited to ten, but only those columns are used where the column name matches one of the following recognized keywords:

  • X - position in x in meters
  • PX or XPRIME - momentum in x normalized to mc or divergence in x, respectively
  • Y - position in y in meters
  • PY or YPRIME - momentum in y normalized to mc or divergence in y, respectively
  • T or Z - longitudinal position in seconds or meters, respectively
  • P or GAMMA - total momentum or energy, normalized to mc or mc2, respectively.

The longitudinal position has to be defined exclusive either to be T or Z. The same is valid for the other pairs listed above. If not all 6 dimensions are given GENESIS 1.3 will terminate and report an error message. Note that GENESIS follows the rule that the longitudinal position is reversed if a time is specified by the T column. In this case smaller numbers correspond to particle in the tail of the distribution.

The default behavior of GENESIS 1.3 corresponds to the lines:

? VERSION = 0.1

Note that with this default behaviour the first data line must be the number of particles (= information lines) in the distribution file.