Speaker
Description
The ALICE Collaboration is preparing an upgrade of the experimental apparatus. A key element of this upgrade is the construction of a new silicon-based (12 Gpixels, 10m2) Inner Tracking System. Its readout system consists of 192 readout units that control the pixel sensors, power modules and deliver the sensor data to the counting room. A prototype readout unit has been designed to test the interface between the sensor modules and readout electronics, signal integrity and data transfer reliability, the interface to the ALICE DAQ and trigger, and the system susceptibility to the expected radiation level (both TID and SEU).
Summary
ALICE (A Large Ion Collider Experiment) is an experiment designed to study the properties of the Quark-Gluon Plasma (QGP). The ALICE Collaboration is preparing a major upgrade of the experimental apparatus, planned for installation in the second long LHC shutdown (2018/2019). A key element of the ALICE upgrade is the construction of a new, ultra-light, high-resolution Inner Tracking System (ITS) consisting of 7 concentric barrels. The basic sensing units are custom designed Monolithic Active Pixel Sensor ASICs implemented in CMOS Technology. There are 25,000 sensors in ITS with a total detection surface of 10m2 segmented in 12.5 Giga pixels.
Each sensor of the inner layers is directly connected to the off-detector readout system with a dedicated high-speed link. To reduce the number of data links, in the outer layers sensors are arranged in groups of seven, where only one sensor is connected to the readout system, while the other sensors within the module communicate with this sensor on a local bus. All sensors of each inner barrel module and outer barrel “master” sensors share incoming clock and control lines. The master sensors of the outer barrel modules propagate these signals locally to the other sensors in a module. The clock, control and data links are transmission line segments on the detector modules and thin interconnecting copper cables.
The ITS readout system is a set of 192 Readout Units located 5m from the detector edge. It configures and controls the pixel sensors and power modules. The data stream from the sensors (2 Tb/s) is read out via 3816 high-speed differential custom-made coaxial cables.
A prototype readout unit was designed to test and verify the interface between sensor modules and readout electronics, signal integrity and data transfer reliability, the interface to the ALICE O2 Computing System, the triggering capabilities and system susceptibility to the expected radiation level.
Data from the pixel sensor modules are received by a Xilinx Kintex-7 FPGA. A USB 3.0 interface using the Cypress FX3 controller is provided for data communication with a PC. To verify the FPGA reconfiguration algorithms multiple configuration schemes are available (JTAG, QSPI Flash) including a connection from the GBT-SCA chip to the configuration port of the FGPA. An FMC Mezzanine Card, equipped with GBTx and GBT-SCA chips and Versatile Link transceivers (VTTx and VTRx), is used to test the connection to the control room via GBT link. An optical SFP module is provided as an additional communication channel. The prototype readout unit has been used as a platform for radiation susceptibility tests in a test-beam campaign.
This contribution will describe the features of the prototype readout unit, its performance and results from operation in a radiation environment.
