Silicon strip layout

T.Galatyuk

CBM collaboration meeting, GSI, October 6–8 2004

Outline

• Design of micro strip silicon planes

• Characteristics of strip layout

• Digitization of the hits in the STS

T.Galatyuk October 6-8 2004 CBM collaboration meeting 2

Strip length calculation

Occupancy < 1%

Pitch = 50 m

T.Galatyuk October 6-8 2004 CBM collaboration meeting 3

Central Au+Au collision at 25 AGeV

x coordinate distribution in 3-d STS station

3-d STS station [ 20 cm ]

Region boundary [cm] Strip length [cm]

Phi_nr Phi_nphi R_nr R_nphi Phi_tot R_tot Phi_tot+R_tot Tot N strip

1.1 1.4 0.1 3 1382 60 88 4147 5278 9425 265527

1.4 2.8 0.2 7 1759 280 88 12315 24630 36945 (14000)

2.8 6.0 0.4 8 3519 640 94 28149 60319 88467 {840000}

6.0 10.0 1.0 4 7540 800 126 30159 100531 130690

4-th STS station [ 40 cm ]

2.1 2.8 0.35 2 2639 140 50 5265 7020 12284 303792

2.8 5.6 0.7 4 3519 560 50 14064 28128 42191 (53000)

5.6 12.0 1.6 4 7037 1280 47 28149 60319 88467 {840000}

12.0 20.0 2.0 2 15080 1600 63 60319 100531 160850

5-th STS station [ 60 cm ]

3.1 4.0 0.45 2 3896 180 56 7801 10066 17867 414964

4.0 8.0 1.0 4 5027 800 50 20106 40212 60319

8.0 20.0 2.0 6 10053 2400 63 60319 150796 211115

20.0 30.0 5.0 2 25133 2000 38 50265 75398 125664

6-th STS station [ 80 cm ]

4.1 5.6 1.5 1 5152 300 23 5139 7020 12159 457982

5.6 11.6 2.0 3 7037 1200 36 21112 43731 64842 (500000)

11.6 20.0 4.2 2 14577 1680 30 29142 50245 79388

20.0 40.0 5.0 4 25133 4000 50 100531 201062 301593

7-th STS station [ 100 cm ]

5.1 7.0 1.9 1 6409 380 23 6393 8774 15167 642229

7.0 15.0 4.0 2 8796 1600 24 17593 37699 55292 (782000)

15.0 30.0 5.0 3 18850 3000 38 56549 113097 169646

30.0 50.0 5.0 4 37699 4000 63 150796 251327 402124

Total number of strip in 3 7 STS = 2.084E+06

First layer of strips Second layer of strips

r

Occupancy

T.Galatyuk October 6-8 2004 CBM collaboration meeting 6

Occupancy for = 0o

first layer second layer

T.Galatyuk October 6-8 2004 CBM collaboration meeting 7

Implementation of resolution

1. The total charge per hit is smeared Gaussian-like over the hitted strip and its next and second next neighbors

2. A noise (poissonian with constant mean for each strip) is added

3. Having the charge in each strip, the center of mass is determined as the hit position

Charge per strip

Resolution

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dependence

Dependence ch on noise

ch = 15.24 mch = 15.19 m

Digitization result

number of zone

num

ber

of h

its

3-d STS 4-th STS 5-th STS

6-th STS 7-th STS

T.Galatyuk October 6-8 2004 CBM collaboration meeting 9

MC hits (points)

reconstructed hits

Total number of strip

265527 398876

0.1 0.1

0.2 0.14

0.4 0.2

1.0 0.5

Strip length in3-d STS station

[cm]

T.Galatyuk October 6-8 2004 CBM collaboration meeting 10

Possible way to decrease the number of hitsDecrease the strip length

3-d STS