Information about the new FineMesh B-field option

From GlueXWiki
Jump to: navigation, search

A new "fine-mesh" option for the magnetic field map is now available. The code interpolates over the coarse field map in CalibDB in fine bins, currently set to 1 mm steps in both z and r. The option is available in a jana program by setting the -DBFIELD_TYPE=FineMesh parameter. If EVIO is not available, the code generates the fine-mesh map in memory at the start of a run. If EVIO is available, the fine-mesh B-field data is written to the current working directory and is read in at the beginning of execution the next time the executable is called.

To use the FineMesh field option, you will need to update the DANA and HDGEOMETRY libraries.

Benchmark results (in Hz) on ifarml6 with 4 threads analyzing single particle events (0.1-3.1 GeV/c) with no background and one mass hypothesis:

          Kalman Filter    Least-squares (ALT1)
          protons pions    protons pions
-----------------------------------------------
FineMesh    65.1  58.2       51.0  59.9
Standard    48.5  45.6       47.2  62.8