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ePHENIX forward tracker resolution “study” i n EicRoot framework . Alexander Kiselev EIC TF meeting, BNL Sep , 2 6 2013. Contents. ePHENIX surprisingly good fwd tracker resolution “puzzle” Comparison to the dedicated EIC detector ePHENIX realistic resolution plots in EicRoot framework
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ePHENIX forward tracker resolution “study” in EicRoot framework Alexander Kiselev EIC TF meeting,BNL Sep,262013
Contents • ePHENIX surprisingly good fwd tracker resolution “puzzle” • Comparison to the dedicated EIC detector • ePHENIX realistic resolution plots in EicRoot framework • Summary A.Kiselev
ePHENIX fwd tracker resolution (LoI) -> expected sp/p as good as ~3% at h = 3.0! A.Kiselev
EIC dedicated detector resolution p+ track momentum resolution vs. pseudo-rapidity -> basically the same ~2-3% at h = 3.0 A.Kiselev
EIC dedicated detector support plot #1 p+ track momentum resolution at h = 3.0 vs. Silicon thickness ->material budget matters! A.Kiselev
EIC dedicated detector support plot #2 p+ track momentum resolution at h = 3.0 vs. Silicon pixel size ->detector intrinsic resolution matters as well! A.Kiselev
ePHENIX detector layout A.Kiselev
Other design considerations well, size also matters … sp/p (material budget) ~ 1/L sp/p (intrinsic resolution) ~ 1/L2 (assuming equidistant detector spacing and homogeneous magnetic field) -> and ePHENIXfwd tracker base (L) is at present ~3 times longer … 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 A.Kiselev
ePHENIX resolution plot #1 1.5T constant field; h = 4.0; check contributions (one change at a time) -> so really expect ~10% resolution at 10 GeV/c A.Kiselev
ePHENIX resolution plot #2 1.5T constant field; h = 3.0 vs 4.0 -> a factor of ~3 difference in B*dl integral matters, clear A.Kiselev
ePHENIXmagnetic field map -> field rapidly falls down beyond ~1.5m from the IP A.Kiselev
ePHENIX resolution plot #3 1.5T constant vs realistic field; h = 3.0 & 4.0 -> real field gives a factor of ~2 worse results A.Kiselev
ePHENIX resolution plot #4 realistic field; h = 4.0;“sp/p ~ a*p + b” breakdown ->linear term ~0.7% / GeV/c (~matches LoI number) A.Kiselev
Summary • ePHENIXLoI momentum resolution numbers for forward tracker look reasonable (but whether this resolution suffices or not for RICH-based PID at h=4.0is a different question) • One might want to optimize dedicated EIC detector tracker layout (work started) A.Kiselev