Silicon sensors for LumiCalTwo possible options

Wojciech WierbaInstitute of Nuclear Physics PAN

Cracow

Pads•12 sectors in (15°)

•15 cylinders in r (width 13.33 mm)

•180 pads on half plane

•Inner pad - ~302 mm2

•Outer pad - ~955 mm2

•Capacitance ratio = ~3.16

Odd and even planes rotated by 7.5 deg

Strips•64 concentric strips (width 3.125 mm)

•60 radial strips (3°)

•Inner concentric strip - ~800 mm2

•Outer concentric strip - ~2734 mm2

•Capacitance ratio = ~3.42

•Radial strips - ~1885 mm2

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 platesHalf 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 optionsPads Strips

Masks 1 2

Number of channels 10800 7560

Energy resolution 40% E 31 – 43 % E

Angular resolution ~ 70 - 90 rad ~ 50 – 90 rad

Capacitance ratio on tile 3.16 3.42

Mean area of pad/strip 630 mm2 898 mm2

Smalest pad/strip 302 mm2 267 mm2

Largest pad/strip 955 mm2 1885 mm2

Capacitance ratio 3.16 7.06

Bias, coupling to amplifiers complicated easier

Number of sensors per tile 60 20 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