Status & Plans of Segmentation Y.P.Viyogi(V.E.C.C) Arun Prakash(B.H.U)

Geometry  Compact MuCh:5 abs.+15 detect layers : Monolithic type  Pipe_much.geo  Shield_standard.geo  Cave.geo  Target_au_250mu.geo  Magent_standard.geo  Sts_same_z.geo

Transport 10,000 UrQMD + 5 µ+ and 5µ- (Box Generator) With momentum 2-5 GeV/c Θ :5-25 Φ:  Pad size : 2.5 mm to 1 cm  Digitization, calculate hits loss = 1-Nhits/NMCPoints  Result always ~50%, independent of station/layer and pad size : not quite understandable  Some study into the codes, found that even points having good coordinates were many times not getting assigned any pad/sector during segmentation (or digitization), leading to large loss. Manual Segmentation

Next step… Tried with modular geometry : GEM and with different pad sizes Small number of events, just for checking the numbers Found hit loss negligible, also multiple hits very little Decide to move ahead with Modular geometry, as this is the next and practical step.

Geometry : do we need extra radius Presently the code adds 20cm to the nominal R_max at each station Results in ~25% more number of channels (this is only fictitious) in sectors sitting outside the nominal acceptance Points/hits in the regions beyond nominal R_max do not contribute to tracks Decide to remain within nominal outer radius at each station.

Comparison of two scenario R_max+20cmR_max+0.6cm Station-1 R=70cm

Selection of GEM module and pad size So far excellent work with various ideal and modular geometry by the GSI-PNPI-Dubna group in simulation We slowly move towards realistic detectors GEM foils : routinely made in 30cm X 30 cm size, sector shaped GEM foil made at CERN for RD51 collaboration which is ~50cm long. Even 1m long sectors being tried. FEE board size and mounting on the modules (too early to decide) : horizontal (parallel to detector plane) preferred. Consequence : pad size to be large enough for reasonable real estate of a 2-nXYter Board, approx. 8 cm x 8 cm Optimum pad size : a balance between simulation and hardware efforts

Selection of pad size : particle density

Selection of GEM module and pad sizes Nominal size of GEM assumed : 32 cm X 32 cm Pad sizes 0.5 cm, 1 cm, 2 cm to respect the condition that number of channels must be 2^n. Quick check on segmentation with 50 events

Segmentation : First attempt, guided by particle density ItemPads No of regions No of Channels 256 ~636k V1R int Lx Ly Rout Lx Ly Av. Hit loss ~ 1.5%

V1 : Station1 as seen after segmentation R=70 cm

ItemPads No of regions No of Channels 256 ~430k V2R int----- Lx----- Ly----- Rout Lx Ly How bad can it be ? Av hit loss ~4.8%

ItemPads No of regions No of Channels 256 ~120k V3R int----- Lx----- Ly----- Rout Lx Ly Can we worsen it further ? Av hit loss ~ 14.8%

ItemPads No of regions No of Channels 256 ~528k V4R int Lx Ly Rout Lx Ly Next stage : fine tuning Av. Hit loss ~2.20%

V4 : station 1 after segmentation R=70 cm

Next Steps Transport : UrQMD + PLUTO events in reasonable mix for modular geometry Segmentation: try V4 first Reconstruction: Do the full reconstruction &calculate the efficiency for signal muons, rho, J/Psi etc. Fine tuning of pad sizes/GEM Geometry and then study again…. And again….