1. CALORIMETER system for the CBM detector Ivan Korolko (ITEP Moscow) CBM Collaboration meeting, October 2004

2. Outline  R&D studies technology development prototype module beam tests this summer quality control of mass production  MC feasibility studies

3. Technology development Physics on CBM: 1. low energies → energy resolution → fine sampling very thin lead plates 2. high multiplicities → small Moliere radius very thin plastic plates HERA-B, LHCb : 2.0 mm lead, 4.0 mm plastic, 9%/sqrt(E) RD36, IHEP : ~0.4 mm lead, 1.5 mm plastic, 3%/sqrt(E) Future CBM : ~1mm lead and plastic plates, ~5%/sqrt(E)

4. Technology development (Vladimir)

6. Prototype module Dimensions – 122 x 122 mm 2 (9 light isolated cells) 280 lead plates - 0.5 mm thickness (25 X0) 9x280 plastic plates - 0.5 mm thickness 16 WLS fibers + 1clear fiber per cell GEANT simulations predict ~3%/sqrt(E) resolution (sampling fluctuations only !!!)

7. Prototype module

9. Beam tests Measurements: 1. Energy scan with electrons 5-100 GeV/c energy resolution 2. Scan with 100 GeV/c muons light collection efficiency (!!!) We need some time to analyze test beam data

10. Beam tests Light yield: 800-900 photo electrons per GeV (after a lot of skepticism) additional 3%/sqrt(E) term in energy resolution LHCb modules :~4500 photo electrons per GeV factor 2 is lost due to the reduced volume ratio (Moliere) factor 3 is lost due to the small thickness of plastic (4 mm LHCb vs. 0.5 mm !!!) Conclusions – 1mm plastic plates would be better Production quality is important

11. Beam tests Beam test results allow us: 1. To understand light collection efficiency for a wide range of different plastic plates (0.5 mm – 4.0 mm) Special light transport MC code is developed and tuned with experimental data 2. To improve pure GEANT MC with 2 important features a) light yield (as a function of plastic thickness) b) light collection eff. (as a function of plastic thickness)

12. Production quality Trigger Set-up designed for 30 modules Measuring 5 inner modules at once Using vertical tracks Exposure time ~20 h mixermixer PM mixer housing 1. Complex quality control system in Vladimir (plates+modules) 2. Cosmic muon setup at CERN to check all LHCb modules

13. Production quality 25 lines measured already 125 inner modules (1125 cells) The overall width of MIP signal is about 12 % (still to be improved)

14. Production quality Signal seen by one PMT in 25 different cells. More accurate estimation of module (cell) quality Cells are the same within 6%

15. R&D conclusions First prototype was built and tested 1.Very fine sampling (0.5 mm lead and plastic plates) 2.Adequate light output (even for 0.5 mm plastic plates !!!) We are confident that required module could be built uniformity of light collection efficiency is an issue We have data for tuning of pure GEANT MC which is rather important for further feasibility studies Quality of LHCb modules is very good…

16. MC feasibility studies e/π separation Overlap MinBias (central) events with electrons from J/ψ decays Studying e/π separation (full CBM MC) as a function of: 1) electron production angle 2) calorimeter granularity Simple but very CPU consuming exercise.

17. MC feasibility studies μ/π separation Overlap MinBias (central) events with muons from J/ψ decays Studying μ/π separation as a function of: 1) electron production angle 2) calorimeter granularity Requires longitudinal segmentation !

18. MC feasibility studies Registration of neutral particles – γ, antineutrons Interesting for many applications Opens possibility to register strange barions with neutral particles in final state: 1. anti-(Σ - )  anti-(n) + π + 2. Σ 0  Λ + γ 3. exotics… (like antipentaquark) Other suggestions are welcomed

19. MC development Sergey Kiselev has prepared description of the calorimeter for the last version of CBM MC – cbmroot.