Pixel detector development: sensor Epitaxial wafer with sensor: first design 5 readout chip sensor Production of pixel sensor prototypes using epitaxial silicon layers on a thinned Cz substrate. Different epitaxial layers under test (50 m / 75 m / 100 m). Corresponding target thickness: 100 … 150 m. Photo left: Produced test wafer with different sensors and diagnostic structures. pixel Pad for bump bonding 4 readout chip sensor

Pixel detector development: readout electronics ToPix specifications: Custom made pixel readout chip developed using 130 nm CMOS technology Pixel readout size 100mm x 100mm Chip active area 11.4 mm x 11.6 mm dE/dx measurement ToT, 12 bits dynamic range Noise <0.032 fC (200 e-) Clock frequency 155.52 MHz Time resolution 6.4 ns (1.85 ns rms) Power consumption <<500 mW/cm2 Max. event rate @2·107pbar-p ann/s: ~ 12·106 hits/(cm2·s) Custom made front-end (ToPix) for the pixel detectors. ToPix-specification.

Pixel detector development: Front-end electronics ToPix_v2: Custom made pixel readout chip Electrical scheme of the readout cell 5 Ifb Cint preamp comp baseline restorer DAC 12 7 mask le_reg te_reg cfg_reg control logic ToT bus CLK: INPUT Prototype with 320 readout cells ANALOG DIGITAL Custom made front-end (ToPix) for the pixel detectors. ToPix-specification: …….PLEASE FILL IN Top: Photograph of a reduced prototype (ToPi_v2) connected to ist test board (left) and floor plan (right). Bottom: Pixel cell schematics. Floor plan (left) and Schematics of a pixel cell readout (right). latch enable mask Pixel readout cell, 100 mm x 100 mm size 3

Channel to channel ToT dispersion: Characterization of front-end and sensor prototypes ToPix: Custom made pixel readout chip Channel to channel ToT dispersion:  10 % Epi-Sensors Tests with a 90Sr source Overall characterization measurements indicate full functionality and a good perfomance. Moreover, dedicated test with neutrons and gamma rays prove sufficient radiation hardness TOP: Characterization of the ToPix chip: Gain versus measured time-over treshold indicating good linearity over a high dynamic input range (left). The Time over Threshold technique works also when the preamplifier signal is saturated. Channel to channel variations are independent from the induced charge signal and stay in the order of 10%. (Right) BOTTOM: Characterization of pixel sensors with different epi layer thickness. Leackage current (left), Middle: Distribution of the depletion voltage for different epitaxial diodes. Right: Treshold values for minimizing ionizing particles (MIP) obtained in a measurement with Sr-90 of some assemblies with Alice pixel readout (ToPix is under development!). Values agree well with theoretical expectations.

Measurements with epitaxial pixel prototypes connected to ToPix front-end chip with wire bonding Left: Photograph of the ToPix_v2 prototype wire bonded to his testing board. Some pads are wire connected to pixel devices. Right: 60 keV gamma spectrum as obtained using the Time over Threshold information. Epitaxial silicon pixel size: 125mm x 325mm, 50 mm thick