doubleDist6

• description: Increases the number of particles in a particle input file by successively doubling the number. Intended to be used to increase the number of particles produced by a photoinjector simulation to improve stability of CSR and LSC simulations.

  The algorithm is as follows:

  • For each doubling, insert a new particle ``near'' every pair of existing particles in time. The particle has a new t value, but the same (x, xp, y, yp, p) as one of the original particles.
  • Bin the beam according to t into a large number of bins. Randomize the assignment of p values relative to other coordinates across particles in the same bin, while additionally adding a small random value to each p value.

• synopsis:
  doubleDist6 -input name -output name -doublings number -nt bins

• files:
  • input -- A particle distribution file, such as might be used with sdds_beam.
  • output -- A particle distribution file, such as might be used with sdds_beam.

• switches:
  • -doublings n -- The number of times to double the size of the distribution. The number of particles in the output file is $2^n$ times the number in the input file.
  • -nt bins -- The number of time bins to use for momentum randomization. This helps to avoid having many particles with exactly same momentum.

• author: M. Borland, ANL/APS.

• see also: smoothDist6s