Speaker
Petr Gorbounov
(CERN and ITEP(Moscow))
Description
As part of the LHCb Phase-II upgrade programme, the existing downstream tracking
systems will be replaced by a new scintillating fibre tracker read out by multi-channel
silicon photomultipliers (SiPM). To ensure high tracking performance over the entire
experiment's lifetime, the SiPMs will be operated at sub-zero temperatures, down to -40ºC.
This presentation outlines the proposed SiPM cooling system and describes the design
considerations which led to the choice of the mono-phase liquid cooling solution.
The requirements on the temperature uniformity and stability are discussed, along with
the constraints which thermal considerations impose on the mechanical design of the tracker
modules. The prospective refrigerants (C6F14 and 3M Novec thermal fluids) are compared with
each other, including their effect on the environment.
The SiPM cooling system consists of the remote cooling plant, insulated transfer lines, the local
distribution pipework and the cooling structures inside 288 read-out boxes spread over twelve
5x6 m2 tracker planes. The main design challenges of this system are associated with its large
extent (about 150 m of linear SiPM arrays to be cooled) and severe constraints on the geometrical
envelope and, hense, insulation. Since the SiPM themselves produce very little heat, the estimated
heat load of the cooling plant, 13 kW, is dominated by the heat influx through the insulation of
read-out boxes, interconnection and transfer lines. Main system design parameters, as well
as the latest results of the thermal mock-up tests, are summarised.
Primary author
Petr Gorbounov
(CERN and ITEP(Moscow))
Co-author
Fred Blanc
(Ecole Polytechnique Federale de Lausanne (CH))
