Cooperative International Simulations with McStas

1
Cooperative International Simulations with McStas
Vickie Lynch, Meili Chen, John Cobb, Mark Hagen,
James Kohl, Stephen Miller, Michael Reuter,
Sudharshan Vazhkudai Oak Ridge National
Laboratory Kim Lefmann, Peter Willendrup Riso
National Laboratory in Denmark Emmanuel
Farhi Institut Laue Langevin in France
2
McStas collaboration

• McStas is a neutron ray-trace simulation package
  that simulates neutron scattering instruments.
• Mutual benefits of McStas collaboration
• Access to distributed computing resources on the
  TeraGrid
• Improved performance with MPI parallel
  implementation
• Standardized NeXus output
• Improved visualization with Neutron Science
  portal viewer

3
Data to portal
Visualize from portal
Choose resource
Run on TeraGrid
Visualize from portal
TeraGrid Community Account
Data to portal
4
Simulation portal development Input

• A McStas simulation is available at the Neutron
  Science portal for simulating backscattering
  experiments
• Simulation tab has been added to portal
• Java panel added for input
• Pull-down menu for choosing TeraGrid resource
• JSpinner with min, max, and step for input
  parameters
• Text field for input source file

5
Simulation portal development Access

• Have community certificate and TeraGrid community
  account
• A community certificate will be used to access
  TeraGrid resources.
• Login portal with XCAM/UCAM username and password
• Have permanent log to identify each job with
  XCAM/UCAM username
• Output in TeraGrid community account must be in
  unique directory so jobs do not overwrite jobs of
  other users
• A shared directory is available for output from
  the simulation portal
• Just like approved proposal shared directories
• Community account users can share output

6
Community certificate and accounts

• Distinguished Name
• /DCorg/DCdoegrids/OUPeople/CNJohn Cobb NSTG
  Jimmy Neutron 91500
• Resource Username
• IU
• login.bigred.iu.teragrid.org tg-jneutron
• NCSA
• login-co.ncsa.teragrid.org jneutron
• login-cu.ncsa.teragrid.orgj neutron
• tg-login.ncsa.teragrid.org jneutron
• login-w.ncsa.teragrid.org jneutron
• ORNL
• tg-login.ornl.teragrid.org jneutron
• Purdue
• tg-login.purdue.teragrid.org jneutron
• TACC
• tg-login.lonestar.tacc.teragrid.org tg458668
• tg-viz-login.tacc.teragrid.org tg458668
• UC/ANL

7
Simulation portal development TeraGrid

• GLOBUS used to send jobs to TeraGrid
• Installed on local machine.
• Long term proxy initialized with grid-proxy-init.
• Jobs submitted with globus-job-submit.
• Jobs are monitored with globus-job-status using
  URL returned from globus-job-submit until DONE
  returns.
• Output returned using globus-url-copy.
• SSH key to another local machine from portal to
  run globus.
• TeraGrid machines have files already available
• Compiled executables
• Source input files
• Batch script
• A network weather service available in the
  TeraGrid portal has recent statistics of how long
  it took batch jobs to complete and can be used to
  choose the fastest machine to run the job

8
Simulation portal development Output

• A NeXus file is created on TeraGrid machine
• Simulation portal returns NeXus histogram file
• Output of simulation is NeXus file which is able
  to be viewed by the same 2-D viewer used to
  display experimental results

9
Simulation Portal Future Work

• Gateway needs community proxy for users
• Show status of job on portal input screen
• More simulations in portal
• Data analysis of NeXus files in portal
• fitting

10
Future Goals of McStas Collaboration

• More McStas instrument simulations in portal
• Improved visualization
• Improved performance
• More sample kernels
• Event mode and histogram interfaces
• An analysis interface

11
Simulation portal development DEMO

• Neutron Science approach Neutron Science User
  Portal