Speaker
Description
Within LS4, the LHCb experiment will undergo its major Phase-IIb upgrade. The spectrometer's downstream SciFi tracker will be replaced by a hybrid detector designed to handle higher occupancies and radiation levels. The central high-occupancy regions will employ Monolithic Active Pixel Sensors, while the outer regions will use Scintillating Fibres read by cryogenically cooled Silicon Photomultipliers. For both, new front-end chips are developed. The readout and control will be based on state-of-the-art radiation tolerant electronic components. The presentation provides an electronics-focussed project overview by briefly introducing the basic concept, novel ASICs and then focus on developments for the Technical Design Report.
Summary (500 words)
During CERN's Long Shutdown 4, the LHCb experiment will receive its major Phase-IIb Upgrade. The spectrometer's current Scintillating Fibre (SciFi) tracker will be replaced by a hybrid detector called the Mighty Tracker. The central high-occupancy regions will use Monolithic Active Pixel Sensors (Mighty-Pixel) to withstand a Total Ionising Dose (TID) of about 12 Mrad and 1.2e14 n_eq/cm² Non-Ionising Energy Loss (NIEL) after Run 5, while 95% of the area (23.7 m²/plane) will be covered by SciFis (Mighty-SciFi). To cope with 2 Mrad TID (2e13 n_eq/cm² NIEL) and hit rates approximately twice as high as the currently installed detector, the fibres will be read by cryogenic-cooled Silicon Photomultipliers (SiPMs) and the new PACIFIC++ front-end chip.
For the Mighty-Pixel, several Front-End ASIC candidates are being developed, one of which is the MightyPix. The relevant design blocks have been tested with prototype ASICs in irradiation campaigns, such as the recently completed LF-MightyPix. The submission of the first full-size ASIC in the foreseen technology, MightyPix2, is planned for this autumn. For the integration, in the current design, the pixel sensors are glued and wire-bonded onto hybrid flexes, which form a module with five sensors. These modules are glued onto a lightweight bare stave with integrated cooling, which hosts the readout flexes for data transmission, control, and serial powering, as well as the Patch Panel 0 (PP0) at its end. It connects to the High-Density Interconnect (HDI), the main front-end readout card with lpGBT and Versatile Link+ ASICs, and a power board with bPOL12V DCDC converters.
The readout chain of the Mighty-SciFi starts with SiPMs interfaced to the scintillating fibres in a vacuum box to isolate the cryogenic cooling. Different SiPMs are currently under investigation. Using flex-PCBs, the SiPMs connect to the PACIFIC++ ASIC on a carrier board, of which a recent 8-channel prototype has been submitted. This board connects to the main front-end board with lpGBT and ALDO2 (SiPM HV) ASICs and several mezzanine cards for powering (bPOL12V), data transmission (Versatile Link+), and calibration (light injection system). Stringent space constraints, maintenance accessibility, and the multiple board tasks challenge its layout and design of the cooling box.
Both detector types are arranged in several layers and stations. They share the same type of mechanics and service frame (C-Frames) to connect to the common experiment infrastructure such as low voltage power supplies, cooling, and back-end data acquisition system. Joint efforts, also with other sub-detectors in LHCb, are the procurement of components, e.g., for the low-voltage powering system and the Pixel ASIC and detector layout with the Upstream Pixel Tracker (UP). As for both detector types the radiation level at the powering board is moderate, the applicability of bPOL12V_v6 is under investigation.
The presentation, summarising the input to the Technical Design Report currently being prepared, will provide an overview from the electronics perspective. It will highlight specific aspects in more detail and present the latest results, e.g., from irradiation campaigns, cooling, or powering tests.