Abstract
Abstract An upgrade program is underway to increase the luminosity of the LHC up to about 7.5 × 10 34 cm −2 s −1 in 2027, with the goal of an integrated luminosity of 3000 fb −1 by the end of 2037. This High Luminosity scenario, HL-LHC, presents new challenges of higher data rates and increased radiation hardness for the pixel detector: a non-ionizing fluence of 2.3 × 10 16 n e q /cm 2 an ionizing dose of 12 MGy, is expected on the inner pixel layer for 3000 fb −1 integrated luminosity. To maintain or even improve the performance of the present system, new technologies have to be fully exploited for the so-called Phase-II upgrade. Among them is the future version of front-end chips in 65-nm CMOS by the CERN RD53 Collaboration which supports small pixel sizes of 50 × 50 or 25 × 100 μ m 2 lower thresholds ( ∼ 1000 e − ). For the development of the appropriate planar pixel sensor, CMS has recently launched a submission of n + -p sensors on 6 inch wafers with an active thickness of 150 μ m at Hamamatsu. The submission consists of physically thinned, directly bonded and deep diffused wafers with p-stop or p-spray isolation. A variety of sensors with and without biasing scheme is designed to match the different read-out chips (RD53A, ROC4Sens, etc.) and first hybrid modules are assembled at Fraunhofer IZM. In this document, we will present an overview of the Phase II pixel R&D program and report on preliminary results on the HPK submission.
Highlights
During the Long Shutdown 3 (LS3) of the LHC, the machine will be upgraded to enable instantaneous peak luminosities of 5x1034 cm−2s−1, or even 7.5x1034 cm−2s−1 in the ultimate performance scenario
Among them is the future version of front-end chips in 65-nm CMOS by the CERN RD53 Collaboration which supports small pixel sizes of 50x50 or 25x100 μm2 and lower thresholds (∼ 1000 e−)
At the foreseen inner pixel radius of 3 cm, a fluence of particles corresponding to a non-ionizing energy loss (NIEL) of Φ = 2.3x1016 neq/cm2 and a total ionizing dose (TID) of 12 MGy will be reached after ten years of operation
Summary
During the Long Shutdown 3 (LS3) of the LHC, the machine will be upgraded to enable instantaneous peak luminosities of 5x1034 cm−2s−1, or even 7.5x1034 cm−2s−1 in the ultimate performance scenario. At the foreseen inner pixel radius of 3 cm, a fluence of particles corresponding to a non-ionizing energy loss (NIEL) of Φ = 2.3x1016 neq/cm and a total ionizing dose (TID) of 12 MGy will be reached after ten years of operation. To cope with these radiation levels a readout chip using 65 nm CMOS technology and an architecture where a group of channels shares digital electronics for buffering, control, and data formatting is being developed within RD53 [2], a joint ATLAS-CMS collaboration. For the development of the appropriate radiation hard pixel sensors CMS has initiated R&D submissions to study 3D and thin planar sensors with pixel sizes of 50x50 and 25x100 μm produced by different vendors
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