A.Chernogorov Beam pipe influence on the STS performance A.Chernogorov, S.Belogurov, ITEP, Moscow 14th CBM Collaboration Meeting, October 6.-9. 2009, Split, Croatia
Dec 31, 2015
A.Chernogorov
Beam pipe influence on the STS performance
A.Chernogorov, S.Belogurov,ITEP, Moscow
14th CBM Collaboration Meeting, October 6.-9. 2009, Split, Croatia
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 2
Outline:• Introduction
• Simulation conditions
• Layout of the stations
• Pipe configurations
• Detailed results for one configuration
• Comparative analysis for all configurations
• ConclusionsLeading effect: additional hits produced by delta electrons
This part I will speak about
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 3
Simulation conditions• 100 Central UrQMD Events (Au+Au@25AGeV/c)
(UrQMD1.3 input file14: http://www-linux.gsi.de/~cbmsim/cbm_vmc_doc/input.htm)
• Specially prepared geometry of STS stations (2.5° hole). Previous standard geometry had rectangular holes with constant height and was not suitable for our study.
• Several geometries for Al and Be beam pipe• Track simulation with Geant3 (generation
threshold 30 keV, Energy loss threshold 70 keV) /u/sbelogur/cbm/run/sts_sim_my.C based on standard sts_sim.C
(July09 Cbmroot version)• Track reconstruction using
L1Performance class /u/sbelogur/cbm/run/sts_reco_my.C based on recUrQMD_only.C by I.Vassiliev
• Selection condition of tracks passing near the pipe: not less than one point of a track should belong to the cone with 5° vertex angle (MCTracks&RECOTracks)
• Two level observables – excess hits due to pipe, quality of tracks reconstruction
Selection conditionof tracks near the pipe
for analysis
in order to separate effects of tracking algorithm
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 4
Layout of stationsSpecial geometry was created for us by Anna with square holes of 2.5° aperture. Set of sensors 2, 4, 6, 12, 18 cm. For central ones sizes were introduced manually to follow the 2.5° requirement.
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 5
Layout of stations We have found that with previous geometry hit probability per strip >10% i.e. too many fakes. We introduced a new geometry with sensors of 1.4, 2, 4, 6, 12 cm and all central sensors 2 times shorter than before.
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 6
Pipe configurations
For mechanical stability should be: h~D/E, where h is the thickness of the pipe;D is diameter of the pipe;E is the Young's modulus;E(Be)=300GPa, E(Al)=70GPa
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 7
Hit density for 1, 4, 8 STS stationsDetailed results for Be tube Ø28mm h0.5mm configuration
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 8
Detailed results for Be tube Ø28mm h0.5mm configuration
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 9
Comparative analysis for all configurations
A.Chernogorov 14th CBM Collaboration Meeting , Split, Croatia October 6-9 2009 10
Conclusion
• Effects of pipe are visible for all configurations, especially for reconstruction of secondary tracks and for ghosts
• Lowest effects are observed for cylindrical tube Ø20mm, largest ones for pipe having 2.5° cone’s shape
• Usage of the Be allows to reduce considerably pipe’s effects in comparison with Al