engine

Inserting offsets into SIMC 02/21/06 (rev. 03/12/06)

Here are the offsets:

new beam energy = old beam energy
new sos central theta = old sos central theta + ( 0 +- 1 mrad )
new hms central theta = old hms central theta + ( -0.3 +- 1 mrad)
new sos central P = old sos central P * ( 1 + 0.001 * [ -0.3844-0.01778*exp(|x|**3.3971) +- 1] )
new hms central P = old hms central P * ( 1 + 0.001 * [-1.5 +- 1] )
new ssxptar = old ssxptar - [ 0.00363+0.000001078*exp((|x|+1.0)**2.1) +- 0.0005 rad]

The new sos fieldcorr was inserted into ENGINE/s_fieldcorr.f, and the correction was similar to the 2003 parameterization. Below is the output from the analyzer with the two parameterizations.

Run 48865
2003 C. Xu parameterization

Before correction: central mom = 0.874000013
After correction: central mom = 0.873876989

2004 B. Clasie parameterization

Before correction: central mom = 0.874000013
After correction: central mom = 0.873634815

The sos xptar offset was added to STRACKING/s_physics.f

ssxp_tar     = sxp_tar(ssnum_tartrack) ! This is an angle (radians)
      ssxp_tar_temp = ssxp_tar + s_oopcentral_offset
cAdded for PIONCT 02/21/06
c from 2004 heep data
      ssxp_tar_temp = ssxp_tar_temp
     &     + (0.00363+0.000001078*exp((abs(spcentral)+1.0)**2.1))

and ENGINE/c_physics.f
         xp_e_tar    = hsxp_tar + h_oopcentral_offset
         xp_h_tar    = ssxp_tar + s_oopcentral_offset
cAdded for PIONCT 02/21/06
c from 2004 heep data
         xp_h_tar = xp_h_tar
     &     - (0.00363+0.000001078*exp((abs(spcentral)+1.0)**2.1))
...
         xp_e_tar    = ssxp_tar + s_oopcentral_offset
         xp_h_tar    = hsxp_tar + h_oopcentral_offset
cAdded for PIONCT 02/21/06
c from 2004 heep data
         xp_e_tar = xp_e_tar
     &     - (0.00363+0.000001078*exp((abs(spcentral)+1.0)**2.1))

The hms central theta offsets was added to PARAM/hmsflags.param (NB that a positive change in the central theta in the lab frame corresponds to a negative change in hsyptar)

hpcentral_offset = -0.15 ; sets hpcentral = hpcentral * ( 1. + hpcentral_offset / 100. )

The hms central P offsets was added to PARAM/hmsflags.param

hthetacentral_offset = -0.003; (rad)

An error was found in the heep analyzing kumac on 02/23/06. The heep analyzing kumac that creates the plots below contains the beam energy and central spectrometer angles. These were not changed to include the heep offsets in the initial analysis. The kumac was changed to get the kinematics from the database, which in turn gets this information from the replay output files.

Here is how the peaks looked after replay with these offsets for run 48865.

The peaks are within 1.5 MeV of zero and the coplanarity is almost perfect. The <2MeV differences with zero were checked to be due to the choice of offsets that were not exactly those determined in the heep analysis. The differences between the offsets inserted into replay and those determined in the heep analysis were put into the kumac used to generate these plots. The output is below. The peaks are very close to zero showing that the <2MeV differences are not due to inserting offsets incorrectly into replay, but are due to using approximate offsets in replay.

Panels for all of the settings are here.