| <Note made at 14:11:05 on 9 May 2006 by J.M. Jowett> |
| The following files can be used to define the aperture of the LHC |
| within the MAD-X program: |
| LHCB1ApertureWithBSTolerances.mad |
| LHCB2ApertureWithBSTolerances.mad |
| LHCB1ApertureWithoutBSTolerances.mad |
| LHCB2ApertureWithoutBSTolerances.mad |
| ---------------------------------- |
| These are MAD-X input files which define the aperture of the Beam 1 |
| sequence LHCB1 and the Beam 2 sequence LHCB2, with or without the |
| subtraction of a Beam Screen tolerance for orbit and misalignment |
| according to the LHC functional specifications |
| LHC-VSS-ES-0001 rev 0.2, |
| LHC-VSS-ES-0002 rev 1.2. |
| (Note that this \"Beam Screen Tolerance\" is a different concept from the |
| aperture tolerances (AP_TOL values for MAD's APERTURE command.) |
| These files can be read in after the standard sequence file V6.5.seq for |
| this version of the LHC. They assign an aperture to every element in |
| the two sequences, e.g., with MAD's CALL command from a Linux system |
| with access to CERN AFS (lxplus), e.g., to assign the aperture |
| with tolerances to every element in both rings: |
| CALL,FILE=\"/afs/cern.ch/eng/lhc/optics/V6.500/V6.5.seq\"; |
| CALL,FILE=\"/afs/cern.ch/eng/lhc/optics/V6.500/aperture/LHCB1ApertureWithBSTolerances.mad\"; |
| CALL,FILE=\"/afs/cern.ch/eng/lhc/optics/V6.500/aperture/LHCB2ApertureWithBSTolerances.mad\"; |
| Reading in a \"WithBSTolerances\" file after a \"WithoutBSTolerances\" file will |
| simply replace every aperture value and vice versa. |
| LHCApertureWithBSTolerances.m |
| LHCApertureWithoutBSTolerances.m |
| ------------------------------ |
| These files define a continuous model which is the most complete |
| description possible. It defines the aperture at every azimuth s, |
| reproducing every BPM chamber, transition between chamber types, |
| etc. |
| Either of these files defines a continuous model of the aperture for |
| each of the two sequences LHCB1 and LHCB2 as a Mathematica function |
| (LHCApertureComponent), with or without the tolerances. This model can |
| be read into any Mathematica session, e.g., |
| Get[\"/afs/cern.ch/eng/lhc/optics/V6.500/aperture/LHCapertureWithBSTolerances.m\"] |
| from a CERN Linux system (e.g., lxplus) |
| or |
| Import[\"http://proj-lhc-optics-web.web.cern.ch/proj-lhc-optics-web/OpticsSourceAllVersions.link/V6.500/aperture/LHCapertureWithBSTolerances.m\"] |
| from any computer with Internet access. |
| The function is self-documenting. Once loaded in Mathematica, you can |
| type |
| ?LHCApertureComponent |
| for the usage message. |
| Notes |
| ----- |
| The MAD files described above constitute one of the simplest versions of |
| the aperture model for general use with MAD. |
| They condense the information given in other files in this directory |
| (see, e.g., job.sample.aperture.madx) into a single MAD file for each |
| sequence. The large number of markers defined in the Collimation Model |
| (e.g., for the ends of the beam screens and vacuum chambers) are not |
| included. |
| However, depending on requirements, many further versions are available |
| or can be created. For example: |
| (a) for tracking purposes, you may want to define apertures more densely |
| in drift spaces, perhaps with the density increasing as a function of |
| the local beta function. |
| (b) you may want to add aperture tolerance parameters for the APERTURE |
| command in MAD-X. |
| (c) you may want to insert markers at the points in drift spaces where |
| the aperture changes and at no others (the so-called minimal aperture |
| model). |
| The tools to create these a la carte, can be found in |
| /afs/cern.ch/user/j/jowett/w1/LHC/V6.500/ApertureModel/LHCApertureModel.nb |
| Please contact me if you need further information or a special version. |
| </Note made at 14:11:05 on 9 May 2006 by J.M. Jowett> |
