EMU COCOA Simulation Homepage

     COCOA is used for the simulation and reconstreuction of components in the CMS Link, Barrel, and Endcap Muon (EMU) Alignment systems.  Current versions of the program and additional documentation can be downloaded from the main COCOA software page.  Additional documentation about the manner in which COCOA handles matrices and fitting routines can be found in the CMS note a COCOA's forerunner, SIMULGEO.

     This page provides details on the status of COCOA simulations at FNAL.It offers a description for how paramters are defined, 3D (VRML) models of the simulation geometry, and results when available.   A complete discription of the developement and simulation of the ISR and idealized full CMS EMU alignment system are detailed in Robert Lee's Thesis.


Definition of Simulation Parameters

     The EMU COCOA simulations were constructed directly from CMS production drawings.  The original layout of components and definition of simulation objects was done by David Eartly and Robert Lee in the Summer of 2001.   The original drawings and estimation of parameters are shown below.  A detailed description of the manner in which these components were incorporated into the simulation is given in Appendix A of Robert Lee's thesis.
ME+1 (view of YE1 from IP) ME-1 (view of YE-1 from IP)
ME+2 (view of YE2 from IP) ME-2 (view of YE-2 from IP)
ME+3 (view of YE2 toward IP) ME-3 (view of YE-2 toward IP)
ME+4 (view of YE3 toward IP) ME-4 (view of YE-3 toward IP)


COCOA Simulation Scripts

     The following scripts are fully debugged and should run in COCOA version 1.7.3 and later.  Included are simulations of the EMU alignment scheme and ISR simulations.  The full EMU alignment simulation requires more than 1.5 GB of RAM to execute successfully, so it has been broken into smaller simulations (also included below).  All EMU alignment simulations include full Tranfer Systems and  Z distance meter measurements.

    EMU Alignment Simulations (current with EMU official drawings dated before 6-25-02)

    Simulations from the 2000 CERN ISR Tests

    LINK Alignment Quarter Plane Simulation (courtesy P. Arce)

    Example scripts to be bundled with future COCOA releases

  • Example 1     -     A sample DCOPS sensor calibration bench setup
  • Example 2     -     A simple arrangement of two DCOPS reference sensors and a CSC Chamber
  • Example 3     -     An example illustrating how COCOA can be used locate an object from photogrametric survey data
  • Example 4     -     A complex example modeling the ME1 Disk alignment system


VRML Files

     These files provide an interactive 3D view of the simulation (.wrl files).Files are somewhat non-standard VRML 1.0/2.0 format.You will need VRMLView3.0 (Linux, Win, IRX support) to view the files.Other VRML viewers do not work quite as well.
  • VRML model of the full EMU System [.wrl]
  • Snapshots of the Full EMU Alignment Scheme (jpeg)  [view 1]  [view 2]  [view 3]

Sample COCOA Simulation Results

     Simulations of large systems and small systems compare within 5%.Present work is involved with understanding the relationships between the final reconstructed location of the CSC chambers and the uncertainties on the parameter put into the system.Understanding this should be helpful in optimizing the construction and placement of components.
  • Some results illustrating the relationship between key uncertainties on ME+/-1 and ME+/-2


Sample COCOA Source Code Used For R Lee Thesis Simulations

  • COCOA v2.0.0 source code + modifications used in R. Lee Thesis studies of the EMU Alignment Scheme.  [download]