N. Savic | Searcharxiv

arXiv2016

Investigation of thin n-in-p planar pixel modules for the ATLAS upgrade

In view of the High Luminosity upgrade of the Large Hadron Collider (HL-LHC), planned to start around 2023-2025, the ATLAS experiment will undergo a replacement of the Inner Detector. A higher luminosity will imply higher irradiation levels and hence will demand more ra- diation hardness especially in the inner layers of the pixel system. The n-in-p silicon technology is a promising candidate to instrument this region, also thanks to its cost-effectiveness because it only requires a single sided processing in contrast to the n-in-n pixel technology presently employed in the LHC experiments. In addition, thin sensors were found to ensure radiation hardness at high fluences. An overview is given of recent results obtained with not irradiated and irradiated n-in-p planar pixel modules. The focus will be on n-in-p planar pixel sensors with an active thickness of 100 and 150 um recently produced at ADVACAM. To maximize the active area of the sensors, slim and active edges are implemented. The performance of these modules is investigated at beam tests and the results on edge efficiency will be shown.

physics.ins-det↗

arXiv2016

Thin n-in-p planar pixel modules for the ATLAS upgrade at HL-LHC

The ATLAS experiment will undergo a major upgrade of the tracker system in view of the high luminosity phase of the LHC (HL-LHC) foreseen to start around 2025. Thin planar pixel modules are promising candidates to instrument the new pixel system, thanks to the reduced contribution to the material budget and their high charge collection efficiency after irradiation. New designs of the pixel cells, with an optimized biasing structure, have been implemented in n-in-p planar pixel productions with sensor thicknesses of 270 um. Using beam tests, the gain in hit efficiency is investigated as a function of the received irradiation fluence. The outlook for future thin planar pixel sensor productions will be discussed, with a focus on thin sensors with a thickness of 100 and 150 um and a novel design with the optimized biasing structure and small pixel cells (50 um x 50 um and 25 um x 100 um). These dimensions are foreseen for the new ATLAS read-out chip in 65 nm CMOS technology and the fine segmentation will represent a challenge for the tracking in the forward region of the pixel system at HL-LHC. To predict the performance of 50 um x 50 um pixels at high eta, FE-I4 compatible planar pixel sensors have been studied before and after irradiation in beam tests at high incidence angle with respect to the short pixel direction. Results on cluster shapes, charge collection- and hit efficiency will be shown.

physics.ins-det↗