FWD Software

["Ogawa, Akio" <akio AT bnl.gov>]

Hello

I've updated plots from fwd stream data with my bugs fixed:

https://www.star.bnl.gov/protected/spin/akio/fcs/trackmatch/index.html#202606

https://www.star.bnl.gov/protected/spin/akio/fcs/jpsi/index.html#202606

No Jpsi peak (yet).

One thing I failed to point out yesterday was momentum resolution. See Pythia Jpsi plots for ET(fcs) vs PT(track) at right bottom :

2022 : https://www.star.bnl.gov/protected/spin/akio/fcs/jpsi/dilep.cut4.JPsi.0.png

2026 : https://www.star.bnl.gov/protected/spin/akio/fcs/jpsi/20260603/dilep.cut4...1.png

Compare to “2022” (not sure how FwdTrackig was working at that time… was it using some true info still?), it is much worse and almost no pT resolution now...

Akio

From: Ogawa, Akio <akio AT bnl.gov>
Date: Wednesday, June 3, 2026 at 2:35 PM
To: "Brandenburg, Daniel" <star-fwd-software-l AT lists.bnl.gov>
Subject: Pythia Jpsi sample

Hello

I did produce some Pythia Jpsi samples:

/gpfs01/star/pwg_tasks/FwdCalib/akio/pythia/pythia.JPsi.vz0/pythia.JPsi.vz0.runXXX.fzd

and .MuDst.root and .picoDst.root inn the same dir, where XXX is 1~100 and each contains 200events.

I do get nice Jpsi peak from FCS alone, but no good track matchings.

https://www.star.bnl.gov/protected/spin/akio/fcs/jpsi/20260603/dilep2...1.png

https://www.star.bnl.gov/protected/spin/akio/fcs/trackmatch/20260603/index.html

Now I went to single electron gun (pt=1.5GeV, eta=2.5~4, full phi) events:

cd  ~/fcstrk11/star-sw-fwd/

root4star -b -q runSimFlat.C'(1000)’

root4star -b -q sim.C > log_sim

root4star -b -q pico3.C'(0,11,0)' > log_pico

Here is a part of log_pico on tracks and Ecal clusters:

ev=   1 trk=  0 Type=0 NHit=  8 Cvg=1 Chi2=     9.3 pxyz=  -0.20    0.26    3.53 E=   3.55 ProjE=   1.04   -0.12 ( -43.01   55.74)

ev=   1 trk=  1 Type=2 NHit= -9 Cvg=1 Chi2=    14.3 pxyz=  -0.79    1.17   15.36 E=  15.42 ProjE=   0.07    0.04 ( -38.81   56.99)

ev=   1 trk=  2 Type=1 NHit=  9 Cvg=1 Chi2=    11.5 pxyz= -10.14   14.16  187.51 E= 188.31 ProjE=   0.35   -0.17 ( -40.56   56.63)

ev=   1 clu=  0 det=0 ehp=0 xyz= -38.25   56.02 E=15.396 SigMax/Min= 0.515  0.380 Ctg=1

ev=   3 trk=  0 Type=0 NHit=  8 Cvg=1 Chi2=     3.2 pxyz=  -0.33   -0.64    9.75 E=   9.77 ProjE=  -0.18    0.25    0.00 ( -25.30  -49.61)

ev=   3 trk=  1 Type=2 NHit= -9 Cvg=1 Chi2=     4.1 pxyz=  -1.01   -1.86   28.63 E=  28.71 ProjE=  -0.03    0.02    0.00 ( -26.46  -48.67)

ev=   3 trk=  2 Type=1 NHit= -9 Cvg=1 Chi2=     3.6 pxyz= -10.50  -19.85  302.82 E= 303.65 ProjE=  -0.03    0.13    0.00 ( -26.01  -49.17)

ev=   3 clu=  0 det=0 ehp=0 xyz= -25.25  -48.80 E=19.674 SigMax/Min= 0.466  0.390 Ctg=1

Last 2 numbers for track in () are 

   trk->momentum().X()/trk->momentum().Z()*750.0

   trk->momentum().Y()/trk->momentum().Z()*750.0

as poor man's xy projection to Ecal based on momentum.

I’m using Danie’s dev code and his sim.C macro as well. I’m not sure what I am doing wrong with Ecal projection. 

As far as I can see… pico code looks correct about z position to project to, x100 to store as short, and /100.

It seems like something wrong upstream...

-Akio