Abstract
This article describes the high-speed system designed to meet the challenging requirements for the readout of the new pixel VErtex LOcator (VELO) of the upgraded LHCb experiment. All elements of the electronics readout chain will be renewed to cope with the requirement of ~40-MHz full-event readout rate. The pixel sensors will be equipped with VeloPix ASICs and placed at ~5 mm from the Large Hadron Collider (LHC) beams in a secondary vacuum tank in an extremely high and nonhomogeneous radiation environment. The front-end (FE) ASICs with the highest occupancy will have to cope with pixel-hit rates above ~900 Mhits/s using up to four 5.13-Gb/s data readout links. Each module comprises six VeloPix ASICs, wire-bonded to two FE hybrid boards, while a third hybrid will employ a GBTx ASIC as the control interface. High-speed data will reach the wall of the vacuum chamber through low-mass flexible copper tapes. A custom board routes the signals outside the vacuum tank. On the air side, an optical and power board converts the electrical high-speed signals into optical signals for transmission from the underground cavern to the off-detector electronics that process data and send them to a farm of computers for further analysis. Several tests allowing the validation of the system are described here with special emphasis on a test with proton beams that confirms the correct operation of the whole readout hardware.
Highlights
L HCb [1] is a general-purpose physics experiment in the forward region at the Large Hadron Collider (LHC)
1) gigabit wireline transmitter (GWT) Interface: The readout board firmware architecture shown in Fig. 6 is a significant modification to the LHCb framework as the VeloPix ASIC is the only FE reading out data over a dedicated protocol (GWT) in reference to the VeloPix serializer
The LHCb VErtex LOcator (VELO) is being upgraded during the LHC long shutdown 2 (2019–2020) along with the rest of the LHCb tracking system and readout electronics to allow for an increase in the luminosity by a factor of five
Summary
L HCb [1] is a general-purpose physics experiment in the forward region at the Large Hadron Collider (LHC). The LHCb experiment, in which detector is placed in a cavern 100-m underground, has an excellent tracking resolution δ p/ p ∼ 0.4%, particle identification, and a flexible trigger. The first level of a trigger, which is hardware-based, uses information provided by the calorimeter and muon systems to preselect hadroncollision events at a rate of 1 MHz. All of the data that pass through the first trigger are sent to a CPU farm where the. The LHCb output rate is 5 kHz. During Runs 1 and 2 of the LHC (2010–2018), 9.2 fb−1 of proton–proton col√lisions data were accumulated a√t the center-of-mass energies s = 7 − 8 TeV for Run 1 and s = 13 − 14 TeV for Run 2
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