ePHENIX forward tracker resolution “study”
in EicRoot framework
Alexander KiselevEIC TF meeting, BNL Sep,26 2013
Sep,26 2013 A.Kiselev
Contents ePHENIX surprisingly good fwd tracker resolution “puzzle” Comparison to the dedicated EIC detector ePHENIX realistic resolution plots in EicRoot framework
Summary
Sep,26 2013 A.Kiselev
ePHENIX fwd tracker resolution (LoI)
-> expected sp/p as good as ~3% at h = 3.0!
Sep,26 2013 A.Kiselev
EIC dedicated detector resolutionp+ track momentum resolution vs. pseudo-rapidity
-> basically the same ~2-3% at h = 3.0
Sep,26 2013 A.Kiselev
EIC dedicated detector support plot #1p+ track momentum resolution at h = 3.0 vs. Silicon thickness
-> material budget matters!
Sep,26 2013 A.Kiselev
EIC dedicated detector support plot #2p+ track momentum resolution at h = 3.0 vs. Silicon pixel size
-> detector intrinsic resolution matters as well!
Sep,26 2013 A.Kiselev
ePHENIX detector layout
ePHENIX EIC ratio
XY-planes # 5 8 5:8
Material per plane ~ 0.86% X0 ~ 0.20% X0 ~4 worse
Plane resolution ~ 50mm < 6mm ~8 worse
Magnetic field ~ 1.5T ~ 3.0T ~2 worse
Sep,26 2013 A.Kiselev
Other design considerations
sp/p (material budget) ~ 1/Lsp/p (intrinsic resolution) ~ 1/L2
well, size also matters …
-> and ePHENIX fwd tracker base (L) is at present ~3 times longer …
(assuming equidistant detector spacing and homogeneous magnetic field)
Sep,26 2013 A.Kiselev
ePHENIX mock-up in EicRoot 5x XY GEM stations at predefined locations 50 micron gaussian resolution and 0.86% rad.length per plane Either constant 1.5T or real-life BABAR-for-ePHENIX field RICH material: 1.0% rad.length entrance window & ~1m thick CF4
gas volume
p+ tracks
Track fitting using Kalman filter
Sep,26 2013 A.Kiselev
ePHENIX resolution plot #1
-> so really expect ~10% resolution at 10 GeV/c
1.5T constant field; h = 4.0; check contributions (one change at a time)
Sep,26 2013 A.Kiselev
ePHENIX resolution plot #2
-> a factor of ~3 difference in B*dl integral matters, clear
1.5T constant field; h = 3.0 vs 4.0
Sep,26 2013 A.Kiselev
ePHENIX magnetic field map
-> field rapidly falls down beyond ~1.5m from the IP
Sep,26 2013 A.Kiselev
ePHENIX resolution plot #3
-> real field gives a factor of ~2 worse results
1.5T constant vs realistic field; h = 3.0 & 4.0
Sep,26 2013 A.Kiselev
ePHENIX resolution plot #4
-> linear term ~0.7% / GeV/c (~matches LoI number)
realistic field; h = 4.0; “sp/p ~ a*p + b” breakdown
Sep,26 2013 A.Kiselev
Summary ePHENIX LoI momentum resolution numbers for forward
tracker look reasonable (but whether this resolution suffices or not for RICH-based PID at h=4.0 is a different question)
One might want to optimize dedicated EIC detector tracker layout (work started)