ALPIDE, the Monolithic Active Pixel Sensor for the ALICE ITS upgrade

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• 作者：M. Mager ^{Magnus.Mager@cern.ch" class="auth_mail" title="E-mail the corresponding author} ; On behalf of the ALICE Collaboration
• 关键词：Tracking detectors ; MAPS ; ALICE
• 刊名：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
• 出版年：2016
• 出版时间：11 July 2016
• 年：2016
• 卷：824
• 期：Complete
• 页码：434-438
• 全文大小：1356 K

文摘

A new 10 m² inner tracking system based on seven concentric layers of Monolithic Active Pixel Sensors will be installed in the ALICE experiment during the second long shutdown of LHC in 2019–2020. The monolithic pixel sensors will be fabricated in the 180 nm CMOS Imaging Sensor process of TowerJazz. The ALPIDE design takes full advantage of a particular process feature, the deep p-well, which allows for full CMOS circuitry within the pixel matrix, while at the same time retaining the full charge collection efficiency. Together with the small feature size and the availability of six metal layers, this allowed a continuously active low-power front-end to be placed into each pixel and an in-matrix sparsification circuit to be used that sends only the addresses of hit pixels to the periphery. This approach led to a power consumption of less than $40\mathrm{mW}{\mathrm{cm}}^{-2}$, a spatial resolution of around 5 μm, a peaking time of around 2 μs, while being radiation hard to some ${10}^{13}1\mathrm{MeV}{\mathrm{n}}_{\mathrm{eq}}/{\mathrm{cm}}^2$, fulfilling or exceeding the ALICE requirements.

Over the last years of R & D, several prototype circuits have been used to verify radiation hardness, and to optimize pixel geometry and in-pixel front-end circuitry. The positive results led to a submission of full-scale (3 cm×1.5 cm) sensor prototypes in 2014. They are being characterized in a comprehensive campaign that also involves several irradiation and beam tests. A summary of the results obtained and prospects towards the final sensor to instrument the ALICE Inner Tracking System are given.