4.13 define_screen

• description: Defines a series of diagnostic “screens” for placement in the beam path. A single define_screen command can be used to produce output of beam parameters at a series of equispaced longitudinal positions.
• example:
  &define_screen  
      template = "gunRun-%03ld.sdds",  
      z_position = 0.01,  
      delta_z = 0.01,  
      number_of_screens = 5,  
      start_time = 1e-9,  
      direction = "forward"  
  &end

  Defines a series of 5 screens for detection of forward-moving particles, The screens are positioned at z coordinates of 1, 2, 3, 4, and 5cm, with data going to files named gunRun-000.sdds, gunRun-001.sdds, etc. Detection begins only after 1ns of simulated time.

• synopsis and defaults:
  &define_screen  
      STRING filename = NULL;  
      STRING template = NULL;  
      double z_position = 0;  
      double delta_z = 0;  
      long number_of_screens = 1;  
      double start_time = 0;  
      STRING direction = "forward";  
  &end

• details:
  • filename: Name of an SDDS file to which to write the data. Used only if number_of_screens = 1.
  • template: Template for creating the names of SDDS files to which to write data. The template must contain a C-style format specifier for a long integer. The template is used as an argument to the C function sprintf to create each filename in turn.
  • z_position: The position (or starting position) of the screen (or series of screens), in meters.
  • delta_z: In number_of_screens is greater than 1, gives the distance in meters between successive screens.
  • number_of_screens: The number of screens in the series.
  • start_time: The starting time in seconds for accumulation of data.
  • direction: The direction in which particles must be traveling in order to be recorded by the screen. May be ”forward” or ”backward”.