STS simulations Layout digitizers performance Radoslaw Karabowicz GSI

STS simulations: Layout, digitizers, performance Radoslaw Karabowicz GSI

STS detector Tracking detector: - low-mass detector - full azimuthal angle coverage - polar angle coverage: from 2. 5° to 25° - high track density in the inner-most region - high collision rate - vertical magnetic field 2

STS design Silicon Tracking System: 8 stations (at 30, 35, 40, 50, 60, 75, 90 and 100 cm away from the target) build from micro-strip double-sided silicon sensors (~300 mm thick, 6 cm wide, 2÷ 6 cm high) with narrow strips (60 mm): vertically oriented on the front side and slightly rotated on the back side (by 15°) readout electronics located in the bottom and top parts outside of defined acceptance sensor readout ensured by low-mass microcables small sensors in the inner region to reduce the occupancy, outer regions covered by larger sensors, or even chained sensors, to minimize number of channels 3

Module FEB with n-XY 8 8 n-XY s s TERTER 2 -6 cm Cable Silicon sensor ~6 cm 4

Overlaps vs gaps Example realizations of the station #3 at z=40 cm overlaps intermediate 5 39. 65 40 40. 35

Overlaps vs gaps – tracking efficiency Overlap geometry Gap geometry Traversing overlaps does not overall efficiency Traversing gaps does 1 gap, 2 gaps change tracking efficiency 1 overlap, 2 overlaps Work done by the GSI Summer Student 6 Maksym Zyzak from National University, Kyiv

Overlaps vs gaps – momentum resolution Overlap geometry Gap geometry Traversing overlaps does not overall resolution Traversing gaps does change momentum resolution 1 gap, 2 gaps change momentum resolution 1 overlap, 2 overlaps Work done by the GSI Summer Student 7 Maksym Zyzak from National University, Kyiv

Realistic detector response Ideal response: Realistic response: The hit is determined by the track position in the center of the silicon detector Physical processes: -charge smearing -collection efficiency -Lorentz angle due to magnetic field 8

Realistic response - models CMS @ LHC w/2 p/2 transverse tracks CBM: |B| = 1 T Holes: Q = 1. 5°, Dx = 8 mm Electrons: Q = 7. 5°, Dx = 40 mm 9

Ideal Realistic Hit density 0 -35 hits/cm 2 0 -31 hits/cm 2 Strip occupancy 0 -5. 8% 0 -11% 10

Ideal Realistic Cluster length 1 strip from definition of ideal response 1. 4 -2. 3 strips Hit finding efficiency <eff> = 98. 6% 94 -100% <eff> = 91. 9% 54 -99% 11

Realistic response - results Ideal response: Realistic response: 12

13 Ideal

14 Realistic

Detector X-ray station 5 (z = 60 cm) x/x 0 y[cm] Radiation length thickness 6 million 10 Ge. V/c pions in Geant x/x 0 STS detector - silicon detector thickness: currently 0. 3% x[cm] x 0 (300 mm) - station with cables and support structure: up to 1% x 0 -total vertex/tracking system: < 15% x 0 15

Summary Realistic geometry that matches recent discussions on construction possibilities available (thanks to Sergey Belogurov) The geometry has been tested by Irina Rostovtseva, Maksym Zyzak and me More discussion with engineers needed (more) The realistic digitizer and cluster finder ready Detector response study essential 16

Deltas – expected behavior Station 1 0. 3 e- / beam particle Station 4 0. 12 e- / beam particle Station 5 0. 08 e- / beam particle 17

Deltas – surprising feature Station 6 0. 15 e- / beam particle 0. 05 – 0. 1 Station 7 0. 15 e- / beam particle Station 8 0. 03 e- / beam particle 0. 03 – 0. 12 HEAR MORE ABOUT THIS FROM YOURI’s PRESENTATION 18

Delta electrons study by Iouri Vassiliev 19

Left-right asymmetry 20

Ideal Realistic Hit density 0 -35 hits/cm 2 0 -31 hits/cm 2 Strip occupancy 0 -5. 8% 0 -11% 21

Ideal Realistic Cluster length 1 strip from definition of ideal response 1. 4 -2. 3 strips Hit finding efficiency <eff> = 98. 6% 94 -100% <eff> = 91. 9% 54 -99% 22

STS test beam early results Radoslaw Karabowicz GSI

Silicon sensor FE B n- w TE XY it h R Test beam setup Silicon sensor F E B n- w TE XY it h R 24

yield First signals from beta source 90 Sr source Time in epochs 25

yield First signals from beta source 90 Sr Noise Beta source ADC channels 26

yield Beam in Cave C!!! Screams: Do we have beam? ? Playing with threshold Time in epochs 27

Beam bunches Hits Beam counter Yield time [a. u. ] 28

Vertical strips on detector 1 channel number Horizontal strips on detector 2 Channel number correlations Horizontal strips on detector 1 Vertical strips on detector 2 channel number 29