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 typePipe_much.geoShield_standard.geoCave.geoTarget_au_250mu.geoMagent_standard.geoSts_same_z.geo

Transport• 10,000 UrQMD + 5 µ+ and 5µ- (Box Generator)• With momentum 2-5 GeV/c• Θ :5-25• Φ: 0-360

Pad size : 2.5 mm to 1 cmDigitization, calculate hits loss = 1-Nhits/NMCPointsResult always ~50%, independent of station/layer and pad size : not quite understandableSome 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+20cm R_max+0.6cm

Station-1Station-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

Item Pads

No of regions

2 2 2 1 1

No of Channels

256 256 256 256 256 ~636k

V1 R int 32 50 70 - -

Lx 0.5 0.5 1.0 - -

Ly 0.5 0.5 1.0 - -

Rout 70 96 120 150 182.5

Lx 1.0 1.0 2.0 2.0 2.0

Ly 1.0 1.0 2.0 2.0 2.0

Av. Hit loss ~ 1.5%

V1 : Station1 as seen after segmentation

R=70 cm

Item Pads

No of regions

1 1 1 1 1

No of Channels

256 256 256 256 256 ~430k

V2 R int - - - - -

Lx - - - - -

Ly - - - - -

Rout 70 96 120 150 182.5

Lx 1.0 1.0 2.0 2.0 2.0

Ly 1.0 1.0 2.0 2.0 2.0

How bad can it be ?

Av hit loss ~4.8%

Item Pads

No of regions

1 1 1 1 1

No of Channels

256 256 256 256 256 ~120k

V3 R int - - - - -

Lx - - - - -

Ly - - - - -

Rout 70 96 120 150 182.5

Lx 2.0 2.0 4.0 4.0 4.0

Ly 2.0 2.0 4.0 4.0 4.0

Can we worsen it further ?

Av hit loss ~ 14.8%

Item Pads

No of regions

2 2 1 1 1

No of Channels

256 256 256 256 256 ~528k

V4 R int 25 40 - - -

Lx 0.5 0.5 - - -

Ly 0.5 0.5 - - -

Rout 70 96 120 150 182.5

Lx 1.0 1.0 2.0 2.0 2.0

Ly 1.0 1.0 2.0 2.0 2.0

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 geometrySegmentation: try V4 firstReconstruction: 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….