Commissioning and first results from the CMS phase 1 upgrade pixel detector

TL;DR

The CMS phase 1 pixel detector upgrade enhances tracking performance at high luminosity, featuring additional layers, digital readout, improved cooling, and successful commissioning with promising initial results from LHC data.

Contribution

This paper presents the design, commissioning, and initial performance results of the upgraded CMS phase 1 pixel detector, highlighting technological improvements over the previous system.

Findings

Enhanced hit resolution and tracking performance

Successful commissioning and operation at LHC

Improved vertex resolution

Abstract

The phase 1 upgrade of the CMS pixel detector has been designed to maintain the tracking performance at instantaneous luminosities of $2 \times 10^{34} \mathrm{~cm}^{-2} \mathrm{~s}^{-1}$. Both barrel and endcap disk systems now feature one extra layer (4 barrel layers and 3 endcap disks), and a digital readout that provides a large enough bandwidth to read out its 124M pixel channels (87.7 percent more pixels compared to the previous system). The backend control and readout systems have been upgraded accordingly from VME-based to micro-TCA-based ones. The detector is now also equipped with a bi-phase CO$_2$ cooling system that reduces the material budget in the tracking region. The detector has been installed inside CMS at the start of 2017 and is now taking data. These proceedings discuss experiences in the commissioning and operation of the CMS phase 1 pixel detector. The first results from the CMS phase 1 pixel detector with this year's LHC proton-proton collision data are presented. The new pixel detector outperforms the previous one in terms of hit resolution, tracking, and vertex resolution.