Serial powering and high hit rate efficiency measurement for the Phase 2 Upgrade of the CMS Pixel Detector

Abstract

A serially powered pixel detector is the baseline choice for the High Luminosity upgrade of the inner tracker of the CMS experiment. A serial power distribution scheme, compared to parallel powering, requires less cable mass, offers higher power efficiency and is less susceptible to voltage transients. A prototype pixel readout chip has been designed for serial powering in 65 nm CMOS technology by the RD53 collaboration. Performance results from testing the prototype chip, called RD53A, are reported. The performance of RD53A operating in a chain consisting of four chips powered in series is compared with the performance under a conventional powering scheme. Additionally, the readout efficiency of RD53A in a high hit rate environment in different operation modes is presented for the first time. The results indicate that serial powering is a robust and reliable power distribution scheme.

Prototype Module Construction for the High Luminosity Upgrade of the CMS Pixel Detector

“…Figure 3a shows the distribution of the ENC per pixel over the four ROCs of a quadchip module. Except for typical chip to chip variations, the noise behaviour shows no prominent structures and remains around 70 e − as measured on single-chip PCBs [11].…”

The Impact of Microelectronics on High Energy Physics Innovation: The Role of 65 nm CMOS Technology on New Generation Particle Detectors

“…Simulation studies of hit losses determined by the local storage in the pixel region for the two different architectures are shown in Figure 7, from [18,19]. Measurements [20] of readout RD53A efficiency for different trigger latency vs single hit flux have been done. An X-ray source (60 kV Chrome target with a kα peak of 5.4 keV) generates a single hit physical signal to the silicon pixel sensor bump-bonded to RD53A.…”

“…FIGURE 8 | Efficiency vs hit rate flux generated by X-ray, that generate single hit clusters: data well fit the simulation prediction. Simulation prediction for clustered hits coming from particles are also shown, see text From [20].…”

The Upgrade of the CMS Inner Tracker for HL-LHC

“…For this the modules are connected in serial powering chains [15] of up to eleven modules [4]. A controlled splitting of the supply current between the chips on the module (connected in parallel) is needed and achieved by dedicated Shunt-LDO regulator blocks [16] implemented in the readout chip (see also [8] in the same issue). The ATLAS and CMS pixel detectors for HL-LHC are the first large scale application of serial powering in a detector system.…”