Add section Track Finder for mCBM

CBM-PR-2020-Algo.tex

@@ -64,7 +64,7 @@ reconstruction and time-slice-based reconstruction at 0.1~MHz, 1~MHz and
 \end{table}
 
 As one can see from Tab.~\ref{table:eff} for the low IR~case the overall 
-track reconstruction efficiency is even higher than for e-b-e case due to the 
+track reconstruction efficiency is even higher than for 3D~case due to the 
 help of additional time measurement of hits, which is not present for the 
 3D~case. For the highest IR scenario the efficiency degradation of about~6\% 
 is observed. Here one has to note that the effect is not solely due to the 
@@ -104,8 +104,28 @@ reconstruction algorithms to so-called sub-slices containing of about
 100~events for track reconstruction and reconstruct them with no speed 
 degradation. The splitting algorithm is currently under development.
 
-\section{Global tracker}
-progress for mini-CBM, further extension to the full CBM
+\section{Track Finder for mCBM}
+
+The CA~tracker used in STS was modified and adapted for the reconstruction
+of straight tracks for the case of mCBM in the absence of magnetic field. 
+The modified algorithm consists of the same steps as original one and the
+triplets are built trough the whole detector system and binned into tracks. 
+However, the extrapolation is done with a straight line track model,
+momenta is not defined and filtered and binning triplets into tracks
+is done with no momenta cut. 
+
+In order to test the reconstruction performance 1000~AgAg UrQMD central events
+at 1.65~$A$GeV collision energy were simulated using 
+the mcbm\_beam\_2020\_03 setup. For the current development 
+stage v20d mSTS and v20b mTOF~(Time-of-Flight) sub-detectors were included.
+For efficiency calculations the same definitions were used as for the full
+CBM case. The resulting tracking efficiency is about 96\% with ghost fraction
+of about 18\%, which is expected to improve after including all the 
+sub-detector systems. 
+
+Similar approach of extending the existing~CA track finder is used for the 
+global CA-based track reconstruction algorithm, which is currently under 
+development.
 
 \section{Event builder}