Speaker
Description
Summary
As a consequence of the increasing luminosity at SLHC with respect to the LHC more particles are expected in the CMS tracker. This leads to the need for a higher read-out granularity and in general a higher functionality to preserve the good performance of the experiment. Therefore a new tracker has to be built.
An evaporative CO2 system should fulfil the requirements of effective and low mass cooling. It is planned to employ it already in the phase-I upgrade of the pixel detector and later also in the phase-II upgrade of the whole tracker.
In Aachen we have built and commissioned a recirculating CO2 test system. Our aim is to gain experience in working with this kind of system and to determine several important parameters such as the lowest operating temperature and the overall operating conditions for a stable system. With our set-up we can achieve a maximum cooling power of 500 W and cover a temperature range in the detector between -45°C and +20°C. We want to manage the continuous operation and precisely control temperature and flow. The maximum pressure in the system is 100 bar.
We performed dryout measurements at different saturation temperatures to determine which flow is needed to dissipate a certain heat load. Additionally we started to analyse the pressure and temperature drop over the pipe to investigate how accurate we can control the detector temperature. All measurements will be compared to theoretical models.
A main goal is to determine the optimal cooling pipe routing and thermal contacts between the cooling system and the sensors and electrical devices. With the knowledge gained by these measurements we would like to contribute to future module designs of the new strip tracker for phase-II.
