Central-Cluster Tracking Takashi Hachiya Maya Shimomura

Status Write the tracking code using Central Arm track and Cluster in SVX. – Algorithm has been explained by Yasuyuki and Maya before. – The algorithm was tested in the Ntuple based analysis. – Powerful tracking method since the CNT track is well established It is feasible to get reliable result even the small number of associated cluster. But acceptance is very limited, mush smaller than the SVX coverage. Code status – SvxCentralClusterReco – SubSysreco module 1 st version is in progress. Algorithm – Make cluster links associated with single central track. Based on Primary Vtx and p, the0, phi0 from a track One track may have some candidate clusters at each layer. We call this links of the candidate clusters as “cluster link”. – Shown in the cattoon – Choose the best cluster link Use least Chi2-square

Cluster Link y x B3 B2 B1 B0 B3B2B1B0 links of the candidate clusters : 6 links Links starts from outer layer Run |Zbbc|<8cm, 10<Sum(bbccharge)<500, 12 files (Akiba-san’s DST) dz in B3 dproj in B2 dz in B2 dproj in B3 dproj in B2 – dproj*C in B3 dproj in B3 dz = zhit – z projection Choose Best link shown as red C is an arbitrary factor for alignment correction

Chi-Square Using least Chi-Square method B3 Projected B2 Projected B3 B2 dproj Beam center (starting point of initial CNT track projection) Initial CNT track projection Actual track If alignment is perfect, dproj in B3 is DCA

Momentum dependence of dproj in B2 a = 0.058, b = phi0 dproj in B2 = (dproj2-dproj3) p[GeV/c]

Outlook Improve the tracking code – Chi-square calculation to choose the best link Tune the cut parameters – dproj, dz in first and second step Alignment – Hidemitsu and Maya are working. Others – Update SvxParManager and SvxDecode SvxPixelHotDeadMap is used in the SvxDecode. Already Committed to CVS