Speaker
Description
The Beam Gas Ionization (BGI) profile monitor, situated within the PS and SPS accelerators, requires a radiation-tolerant readout system to transfer data from the challenging accelerator surroundings to the back-end for processing. Operating 1m below the beam pipe, the front-end must ensure reliability, given limited hardware access, and preserve signal integrity for the high-speed Timepix3 data (32 channels at 320 MHz). The outcome is the Beam Instrumentation PiXeL (BIPXL) readout system, employing radiation-hardened components like the GBTx and the FEASTMP, both developed at CERN. This system will be compatible with forthcoming hybrid pixel detector initiatives in similarly harsh radiation conditions.
Summary (500 words)
Our Beam Instrumentation PiXeL (BIPXL) readout system allows the data acquisition and slow control of Timepix3 hybrid pixel detectors in high radiation environments. Currently, it is employed in the Beam Gas Ionization (BGI) profile monitor situated in the Proton Synchrotron (PS) and in the Super Proton Synchrotron (SPS) complex at CERN. This monitor enables non-invasive, continuous measurement of the beam profile throughout the acceleration. It exploits the ionization of residual gas particles by the passing beam, with the resulting ionized electrons directed towards four Timepix3 detectors.
The Timepix3 detectors are placed directly inside the acceleration beam pipe and generate large amounts of data (total of 32 channels at 320 MHz). This data must be converted to optical format by electronics close to the beam pipe, to be sent to a back-end system located outside of the radiation area. For the back-end, the BIPXL project utilizes the FPGA and Processing System of a Xilinx Zynq Ultrascale+ MPSoC.
The previous BIPXL front-end board was based on a ProASIC3 and a Kintex-7, to package and route the Timepix3 data to optical links, correcting any length mismatch between the data links and the common clock. However, due to the radiation exposure exceeding 50 Gy per year, the FPGA malfunctioned and failed to recover even after reprogramming. Consequently, the front-end board had to be replaced, which posed a challenge due to its proximity to the beam pipe, making access feasible only during technical stops.
This issue, alongside single-events upsets occurring during data acquisition, justified the development of a new rad-hard readout system. The new design incorporates the GBTx chip and VTRx optical transceiver, both radiation hardened components from the Gigabit Transceiver project at CERN, with a TID tolerance of 1 MGy and 500 kGy respectively. The GBTx ASIC facilitates phase alignment of the Timepix3 incoming data signal, ensuring data is sampled in the middle of the eye-opening. For the power conversion, the FEASTMP is employed, a DC/DC radiation-tolerant ASIC with a TID tolerance of 2 MGy. The result is a simpler and more maintainable front-end design, capable of connecting four Timepix3 at 2.56 Gbps each.
These features make the readout system suitable for future applications of Timepix3 for beam instrumentation in high radiation areas. New applications currently under development include: BGI profile monitors for HL-LHC; fast beam loss monitors for rapid deployment in the LHC and telescope to characterize bent crystal in the North Area. Future developments will also be based on Timepix4 and it is planned to upgrade the readout system design to handle the Timepix4’s 16 output data signals at 10.24 Gbps. This data rate will require the use of high-speed PCB material, as well as the Low Power GBT (lpGBT) chip and the VTRx+ transceiver. The DC/DC converters would be updated too, to the bPOL12V version.
