Silicon sensors for LumiCal Two possible options Wojciech Wierba Institute of Nuclear Physics PAN Cracow

Pads 12 sectors in  (15°) 15 cylinders in r (width mm) 180 pads on half plane Inner pad - ~302 mm 2 Outer pad - ~955 mm 2 Capacitance ratio = ~3.16 Odd and even planes rotated by 7.5 deg

Strips 64 concentric strips (width mm) 60 radial strips (3°) Inner concentric strip - ~800 mm 2 Outer concentric strip - ~2734 mm 2 Capacitance ratio = ~3.42 Radial strips - ~1885 mm 2

Wafer size Small wafers are not suitable, causes a lot of tiles per half plane Best wafer size – 24 inch – not available 12 inch wafer acceptable (~300 mm dia)

Tiles of the sensors for both options (12” wafer)

Gap between tungsten plates Half plane of the detector will consist 3 tiles Support to glue tiles and place for the electronics Ceramic plate ~0.5 mm thick Silicon sensor ~0.3 mm thick The gap between tungsten plates should be in order of 1 mm

Comparison of the two options PadsStrips Masks12 Number of channels Energy resolution  40%  E  31 – 43 %  E Angular resolution  ~  rad  ~ 50 – 90  rad Capacitance ratio on tile Mean area of pad/strip630 mm mm 2 Smalest pad/strip302 mm mm 2 Largest pad/strip955 mm mm 2 Capacitance ratio Bias, coupling to amplifierscomplicatedeasier Number of sensors per tile6020 radial, 64 conc.

More realistic MC Rotation of the odd and even planes Angle: pads – 7.5°, strips - 7.5° ? Gaps between tiles (~0.1 – 0.2 mm to be discussed) Pads edges, guard rings Concentric stripes divided in 3 parts for half plane Gap between tungsten plates ~0.8 – 1.0 mm

Conclusions Both options are comparable Number of channels is near the same Resolutions (energy & angular) are near the same Strips needs 2 masks Strips needs probably 2 types of amplifiers Pads have more complicated bias and coupling connections