1. In
past the engine corrected for vertical offset or raster position by an
iterative approach of tracking back to the focal plane, determining the
new focal plane quantities then reconstructing the target quantities.
Replace this by using an optics matrix which has the dependence of
xtar.In rss_replay/DAT add file hms_recon_coeff_xtar_new.dat which has
optics matrix for xtarget dependence.
(Detailed note)
2. Found that for events in which the determination of the target
quantities (delta,y,xp,yp) failed in the call to the reconstruction
subroutines in the code SRC_hms/h_targ_trans.f, the default was to set
delta=100%, xp=yp=.1 and x=y=.01 . This made the proton momentum
twice the central value. So in the variable hsshtrk ( the ratio of
energy deposited in the shower to the proton momentum), these
events gave hsshtrk peak around .5 instead of 1.
Added the variable
h_recon_ok(HNTRACKS_MAX)
which
is filled in the code h_targ_trans.f for each
possible focal plane track.
If the focal plane track
fails
in reconstruction subroutines then h_recon_ok=0,
other wise h_recon_ok=1 for
that track.
(Detailed note)
3. I have added n_sr_adcx_zero and n_sr_adcy_zero so that now
n_sr_offsetx and n_sr_offsety are an offset relative to the coordinate
system of the ntbpm. Also the parameter of slope and offset are
labelled with x and y to go with the ntbpm coordinate system as opposed
to the system of the gsrx_adc and gsry_adc. This means that the
DBASE/rss.database has to be updated. Details on beam position is in a
write up. (
Detailed note )
4. Modified SRC_other/total_eloss.f and PARAM/gtarget.param.01 (
Detailed note
).
5. Add correction to HMS delta for x' focal plane dependence.(
Detailed note )
6. Modified Makefile.Unix by adding to FFLAGS line
-malign-double -fno-automatic
-fno-second-underscore
7. In addition to the delta correction and changes to tracking through
the target, added code to pick best track based on which track hit
closest to the scintillators. These changes were recently added to the
main Hall C engine. (
Detailed
note ).
8. Modified code so that the integrated Bdl for the track through the
target is saved. (
Detailed
note ).
9. Modified code so the map for extended target field could be read in.
Added parameter num_trg_field_steps which is the number of steps
in the target field map. This is set in REPLAY.PARM . Set to 51 for
normal target field map. (
Detailed
note ).
10. Modified SRC_other/trg_track.f and SRC_gen/gen_track.f to implement
a phi dependent part to the target field. This is need for
perpendicular target running to fix an observed x' versus W dependence
seen in the elastic ep peak. Added the parameter
genable_target_field_phi_corr . When genable_target_field_phi_corr=1
the correction is enabled which should only be done for perpendicalur
running. This parameter is set in the DBASE/rss.kinematics . For runs
43220-43611 genable_target_field_phi_corr=1 and for runs 43709-44035
genable_target_field_phi_corr=0 . (
Detailed
note ).
11. To get elastic W peak to be about 938 MeV had to use different
offsets for HMS central momentum for parallel and perpendicular run
periods. For parallel run period use hpcentral_offset = -.42 .
This number is expected from previous determination of the offset from
elastic ep data taken during other experiments. For the perpendicular
run period use hpcentral_offset = 0.0 . This is just a empirical
number to get the W peak at 938 MeV. Previously hpcentral_offset was
set in PARAM/gconstants.param.02 . Now hpcentral_offset is set in
DBASE/rss.database . Runs 43000-43219 set hpcentral_offset = -.42
. Runs 43220-43611 set hpcentral_offset = 0.0 , Runs 43709-44035
set
hpcentral_offset = -.42 .
Plot comparing W
spectrum for parallel and perpendicular target field.
12. ( Dec 22, 2004) Modified SRC_other/trg_track.f so
that genable_target_field_phi_corr .eq. 0 for parallel running
B_scale = 1.0 . Previously B_scale was being set to 0.0 so in effect no
target filed was being used for the replay. So in pass2a this has been
fixed.