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Thermal management issue in module assembly for the ATLAS ITk pixel upgrade

Dec 14, 2019, 3:10 PM
POSTER - Sun: B1F-Meeting room#3, B2F-RAN1/2; Mon-Wed: B1F Meeting rooms #5-6 (International Conference Center Hiroshima)

POSTER - Sun: B1F-Meeting room#3, B2F-RAN1/2; Mon-Wed: B1F Meeting rooms #5-6

International Conference Center Hiroshima

Peace Memorial Park, Hiroshima-shi
POSTER Large scale applications POSTER


Fabian Huegging (University of Bonn (DE))


The ATLAS upgrade programme for the high-luminosity large hadron collider (HL-LHC) includes the replacement of the inner tracking detector with an all-silicon system. The outer layers of the new tracker consist of strip sensors and the inner region is made up of pixel sensors. The harsh radiation environment requires the pixel system to run at low temperature to minimise damage to the silicon sensors. The pixel system runs at a coolant temperature of -35C and the sensors at the end of life will operate at around 0C, but the modules are constructed at room temperature, around 20C. The large difference in temperatures leads to stresses in the pixel modules due to mismatches in the coefficients of thermal expansion of the different materials making up the module. These stresses can result in failure of the solder bumps used to connect the front-end ASICs to the sensors. The stresses in the module have been studied using Finite Element Analysis (FEA), which has identified a number of key factors that contribute to the stresses in the module. The predictions of the FEA model have been compared to the results of thermal cycling measurements on prototype modules.

Submission declaration Original and unpublished

Primary authors

Jens Weingarten (Technische Universitaet Dortmund (DE)) Craig Buttar (University of Glasgow (GB)) Liam Cunningham (University of Glasgow (GB))

Presentation materials