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CBM beam pipe current status and plans

CBM beam pipe current status and plans. Outline The main idea. “Pipe” = “Window”+”Tube”. Balance between measurable particles (window) and ions (tube) Candidate materials for the STS section Studied configurations Results for UrQMD central events at 25 AGeV

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CBM beam pipe current status and plans

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  1. CBM beam pipe current status and plans • Outline • The main idea. “Pipe” = “Window”+”Tube”. Balance between measurable particles (window) and ions (tube) • Candidate materials for the STS section • Studied configurations • Results for UrQMD central events at 25 AGeV • Results for UrQMD central events at 8 AGeV • Status of the ions • MF problem • Plans Sergey Belogurov, Andrey Chernogorov, ITEP, Moscow 15-th CBM collaboration meeting. April 12-16 2010, GSI

  2. Candidate materials for the STS section Be: 4 LHC experiments, Belle, Cleo, CDF etc. 0.3 - 0.5 mm typical thickness Al: HERAb 0.3 mm with stiffening ribs. Information availabe, seems reproducible Relevant background for window: LHCb VELO (Ø800 mm 2 mm Al alloy), machined from a forged billet together with the bellow. SF for the LHCb Be beam pipe is 4-6, for window ~ 3 SF for the HERAb beampipe is ~2 S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  3. Studied configurations Some of “Ideal ” configurations. Effects: cylinder-cone; Be-Al. Al: window – scaling from VELO, cone – “simple” manufacturing. Remarks. 1) 0.3 mm Al = 0.5 mm Be 2) Competition works: JSC “Kompozit” started to think about 0.4 mm Be pipe  “Realistic” configurations. Effects of bellows, width of “Tube”. 1.6º configuration fits to ladders of S. Igolkin without cutting the central rib. Any configuration has a weld 1x10 mm S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  4. Results for UrQMD central events at 25 AGeV Range distribution Figure of merit: integrated range in the pipe: IR=Σli*qi2*ne li – range of a particle inside the pipe qi - its charge ne – relative electron density Total ionization losses and number of d-electrons are roughly proportional to IR window welding Cylinder is optimal with MF, cone – without MF (The same for 8 AGeV). No contradiction with the conclusions of HERAb and LHCb. S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  5. Results for UrQMD central events at 25 AGeV 10x7 Clear trends for “ideal” configurations, for “real” ones no big difference! S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  6. Results for UrQMD central events at 25 AGeV Comparison of Al and Be cones No pipe /c No pipe /c S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  7. Results for UrQMD central events at 25 AGeV Clear trends for “ideal” configurations, for “real” ones more narrow seems slightly better. Vertex resolution much worse than expected from multiple scattering and not indicative. Effects of wrong hits pickup in track-finder Thanks to I. Vassiliev for the basic analysis routine S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  8. Results for UrQMD central events at 8 AGeV 1 Much softer conditions for tracker at SIS-100! STS layout should not be the same as for SIS-300 S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  9. Results for UrQMD central events at 8 AGeV STS with given layout works perfectly with any beampipe. As any optimistic conclusion should be double checked. Probably for SIS-100, STS layout may be simplified and made cheaper. However, taking into account realistic STS simulation may change the answer! S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  10. Results for UrQMD central events at 8 AGeV Only S/B and mass resolution are somewhat sensitive to Al beampipe S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  11. Status of the ions The beam half diameter (90%) at the CBM Target is 2.44mm (H), 1.5mm (V). Angular divergence 0.15° (10-3…-4~0.3°) P1: To be updated for the new cave design At SIS-100 multiple scattering dominates over the angular divergence of the beam, At SIS-300 both effects are comparable 0 – 1.25 deg. 0 – 1.5 deg p && n (%) 70.14 80.79 fragments (%) 96.75 98.62 p && n && fragments (%) 75.81 84.59 MSC of the beam Au-ions in the 250 m gold target For SIS 300 angles in the table are 3 times smaller (1/p msc) 10-3 -> 0.24° Summing up of the scattered ions (~50 per each interaction!) with fragments in PSD. For SIS-300 no improvement S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  12. Status of the ions P2: We have implementedrealistic beam into CBMROOT. However, ions do not work with cut < 1MeV (g3)! Number of hits from ion interactions with the pipe is currently underestimated. Probably all the events with ion interaction can be rejected by number of hits or position of an additional primary vertex. Before getting more definitive results about ions, one has to: - be able to run cbmroot with tunable cuts in GEANT4 - get updated beam properties (plan to do this week) S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  13. MF Problem Input file, D=0.2 kGs Fitted with trunk/field/CbmFieldMapSym2.cxx D=0.7 kGs Wrong coil segment fixed by P. Akishin S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  14. Plans • Establish correct simulations of ions • Flange/window effects on RICH and TRD • Study beam divergence and beampipe effects on the PSD Window is very convenient from mechanical point of view, but… Delta electrons from ions – are they tolerable? STS RICH S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

  15. Conclusions • - Influence of shape and material of the beampipe on the STS performance is studied. Pipe is considered as a composition of “window” and “tube” • For 25 AGeV central events the effects of beampipe are the most prominent in reconstruction efficiency for secondary tracks, • ghost probability, • CPU time, • reconstruction efficiency for secondary particles, • Signal to Background, • Mass resolution • For 8 A GeV only S/B and mass resolution are somewhat sensitive to Al beampipe. It should be checked with more realistic STS • In the presence of MF the best “tube” is narrow cylinder (no ions are taken into account) • Both Be and Al options are feasible. Be provides higher buckling SF and thinner window. • The effects of ions will be studied after update of the beam info and fixing ion simulations problem S. Belogurov, A. Chernogorov, ITEP, Moscow CBM beam pipe, GSI, 12.04.10

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