EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH
GEOMETRIC LAYOUT
The SURVEY command computes the coordinates of all machine elements in
a
global reference system.
These coordinates can be used for installation. In order to produce
coordinates in a particular system, the initial coordinates and angles
can be specified. The computation results are written on an
internal table (survey) and can be written on
an external file. Each line contains the coordinates at the end of the
element.
The last "USEd" sequence is used
except if another one is specified.
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WARNING : in the case a machine geometry is constructed with thick
lenses,
the circumference will change if the structure is converted into thin
lenses (via the makethin
command).
This is an unavoidable feature. ONLY the structure with thick lenses
must be used
for practical purposes.
INFORMATION : The skew dipole component of a MULTIPOLE element
(MULTIPOLE, KSL={FLOAT}) is NOT taken into account in the survey
calculation. You should use a tilted normal MULTIPOLE or BEND instead.
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The survey calculation is launched by a single command line with the
following syntax :
SURVEY, x0=double, y0=double, z0=double,
theta0=double, phi0=double, psi0=double,
file=string, table=string, sequence=string;
parameter
meaning
default value
x0
initial horizontal transverse coordinate
0.0
y0
initial vertical transverse coordinate
0.0
z0
initial longitudinal coordinate
0.0
theta0
initial horizontal angle
0.0
phi0
initial vertical angle
0.0
psi0
initial transverse tilt
0.0
file
name
of external file
null (default name survey)
table
name of internal table
null (default name survey)
sequence
name of sequence to be surveyed
last used sequence
Example : average LHC ring with CERN coordinates.
REAL CONST R0 =
1.0;
! to obtain the average ring
OPTION, -echo, -info;
CALL, file="V6.4.seq.070602";
! follow this link for
the file
OPTION, echo;
BEAM, particle=proton, energy=450, sequence=lhcb1;
USE, period=lhcb1;
! SELECT,
flag=survey,clear;
! uncomment if the optional select
below is used
! optional SELECT to specify a class and the output columns
! SELECT, flag=survey, class=marker, column=name,s,psi;
SURVEY, x0=-2202.21027, z0=2710.63882, y0=2359.00656,
theta0=-4.315508007,
phi0=0.0124279564, psi0=-0.0065309236, file=survey.lhcb1;
WRITE,
table=survey;
! to display the results immediately
STOP;
!***********
The external file "survey.lhcb1" can now be read **************
F.Tecker, March 2006