at.acceptance.touschek#

Module to compute the touschek lifetime of the ring

Functions

get_bunch_length_espread(ring[, zn, ...])

Haissinski equation solver

get_lifetime(ring, emity, bunch_curr[, ...])

Touschek lifetime calculation
get_bunch_length_espread(ring, zn=None, bunch_curr=None, espread=None)[source]#

Haissinski equation solver

Solves the Haissinski formula and returns the bunch length and energy spread for given bunch current and \(Z/n\). If both zn and bunch_curr are None, zero current case, otherwise both are needed for the calculation

Parameters:

ring – ring use for tracking

Keyword Arguments:

  • zn=None – \(Z/n\) for the full ring

  • bunch_curr=None – Bunch current

  • espread=None – Energy spread, if None use lattice parameter

Returns:

Bunch length, energy spread

get_lifetime(ring, emity, bunch_curr, emitx=None, sigs=None, sigp=None, zn=None, momap=None, refpts=None, **kwargs)[source]#

Touschek lifetime calculation

Computes the touschek lifetime using the Piwinski formula

Parameters:

  • ring – ring use for tracking

  • emity – verticla emittance

  • bunch_curr – bunch current

Keyword Arguments:

  • emitx=None – horizontal emittance

  • sigs=None – rms bunch length

  • sigp=None – energy spread

  • zn=None – full ring \(Z/n\)

  • momap=None – momentum aperture, has to be consistent with refpts if provided the momentum aperture is not calculated

  • refpts=None – refpts where the momentum aperture is calculated, the default is to compute it for all elements in the ring, len(refpts)>2 is required

  • resolution – minimum distance between 2 grid points, default=1.0e-3

  • amplitude – max. amplitude for RADIAL and CARTESIAN or initial step in RECURSIVE default = 0.1

  • nturns=1024 – Number of turns for the tracking

  • dp=None – static momentum offset

  • grid_mode – at.GridMode.CARTESIAN/RADIAL track full vector (default). at.GridMode.RECURSIVE: recursive search

  • use_mp=False – Use python multiprocessing (patpass, default use lattice_pass). In case multi-processing is not enabled GridMode is forced to RECURSIVE (most efficient in single core)

  • verbose=False – Print out some inform

  • epsrel (epsabs,) – integral absolute and relative tolerances

Returns:

  • tl – touschek lifetime, double expressed in seconds

  • ma – momentum aperture (len(refpts), 2) array

  • refpts – refpts used for ma calcualtion (len(refpts), ) array