- type: Setup command.
- function: Set basic ring parameters necessary to calculate synchrotron frequency, bunch length, and so on. Once the namelist is processed and written to the standard output file, a list of dependent quantities used in the growth rate calculations are written to the standard output file.

&ringParameters STRING twissFile = NULL; double energyGeV = 0.0 double circumference = 0.0 double energyLossPerTurnMeV = 0.0 double rfVoltageMV = 0.0 long harmonicNumber = 1 double momentumCompaction = 0.0 double relativeEnergySpread = 0.0 double bunchLengtheningFactor = 1.0 STRING bunchLengthTableFile = NULL; STRING bunchLengthUsedFile = NULL; double longDampingTime = 0.0 double transDampingTime = 0.0 double horizontalTune = 0 double verticalTune = 0 double betaxAtRFCavities = 0 double betayAtRFCavities = 0 STRING parameters = NULL; &end

`twissFile`-- If not blank, then parameters of the lattice are taken from the named file, which is assumed to be an`elegant`twiss output file. You must turn on the radiation-integral calculation in`elegant`or`clinchor`will complain of missing data. The data taken from the file are energy, circumference, energy loss per turn, momentum compaction, relative energy spread, damping times, tunes, and beta functions at the cavities. For the last item,`clinchor`looks for elements of type`RFCA`and`RFCW`. It averages the beta functions over all elements found. If you wish to override the values in the file, simply give a nonzero value to the appropriate namelist variable.`energyGeV`-- Energy of the stored beam in units of GeV.`circumference`-- Circumference of the storage ring in meters. Used to calculate revolution frequency .`energyLossPerTurnMeV`-- Energy loss per turn in units of MeV.`rfVoltageMV`-- Peak RF voltage in unit of MV of cavities in ring.`harmonicNumber`-- Ratio between external RF frequency and the revolution frequency . Used to determine .`momentumCompaction`-- Momentum compaction factor. Used to determine unperturbed bunch length.`relativeEnergySpread`-- Relative energy spread. Used to determine unperturbed bunch length.`bunchLengtheningFactor`-- Ratio of expected bunch length and unperturbed bunch length, which might be obtained from a separate potential well calculation. This quantity doesn't affect the calculation coherent synchrotron frequency. The bunch lengthening factor appears only in the bunch form factor in the effective HOM impedance expression. This bunch lengh applies to all bunches in the calculation irrespective of the charge they contain.`bunchLengthTableFile`-- Input file of bunch length in units of seconds as a function of charge to be used for individual bunches in the calculation. This bunch length is used as form factor to reduce the wake fields for a given resonator. This should be used instead of`bunchLengtheningFactor`when possible.`bunchLengthUsedFile`-- Output file of bunch lengths for each bunch defined in the calculation. Columns are bucket number, bunch current and bucnh length. There will be one row entry for every bucket filled. The output files is created only when the file`bunchLengthTableFile`is specified. Recommended value is ```%s.bl`'' where the ```%s`'' is replaced with the rootname of the command file.`longDampingTime, transDampingTime`-- Coherent damping time constants in seconds for the motions in the longitudinal and transverse planes. If one doesn't know the coherent damping times, one may use the synchrotron radiation damping times, which are longer. Damping rates are calculated from the damping times, and are simply added to the CBM growth rates to give the final growth rates. When doing Monte Carlo studies, I prefer to ignore the damping rates by making them explicitly zero in the namelist by setting`longDampingTime`, and`transDampingTime`to zero.`horizontalTune, verticalTune`-- Tunes of the stored beam. Values are required if command`doTransverseMotion`is used.`betaxAtRFCavities, betayAtRFCavities`-- Beta functions at the RF cavities. Values are required if command`doTransverseMotion`is used. The transverse growth rates will scale with one of the two values, depending on which direction is specified in the`doTransverseMotion`command.`parameters`-- Output file containing above parameters plus some calculated ones.