LHCb Muon Station Cooling Studies (done by Ricardo Antunes Rodrigues (ST/CV)) This simulations were made for the Muon Station 1, with the follow assumptions: ● The walls close to the RICH and ECAL systems are considered adiabatic (unless stated otherwise). ● The flux in the muon chambers can only exit by the four smallest areas. ● The flux in the muon chambers is equally distributed through the surfaces. News results since the last meeting: Increased power consumption Introduction of cables

Boundary Location Symmetry CablesInlet/Outlet Global overview of the model

Boundary Location Region 1 Region 2Region 3 Region 4 292Flux [W/m 2 ] 0.494Area [m 2 ] 144Power [W] 193Flux [W/m 2 ] 1.494Area [m 2 ] 288Power [W] 61Flux [W/m 2 ] 4.716Area [m 2 ] 288Power [W] 16Flux [W/m 2 ] Area [m 2 ] 288Power [W]

With Pressure Conditions 0.56Inlet Velocity [m/s] 40Max. Temperature[ºC] 20Inlet Temperature [ºC] 0.76Inlet Velocity [m/s] 41Max. Temperature[ºC] 25Inlet Temperature [ºC] No Cables

1.5 times the Power With Cables Without Cables 0.89Inlet Velocity [m/s] 52/21.4Max./Avg. Temperature[ºC] 20Inlet Temperature [ºC] 0.24Inlet Velocity [m/s] 55/22.2Max./Avg. Temperature[ºC] 20Inlet Temperature [ºC] The boundary with Rich and ECAL systems are considered as 20ºC walls

2.0 times the Power With Cables Without Cables 0.9Inlet Velocity [m/s] 67/21.8Max./Avg. Temperature[ºC] 20Inlet Temperature [ºC] 0.25Inlet Velocity [m/s] 61/22.7Max. Temperature[ºC] 20Inlet Temperature [ºC] The boundary with Rich and ECAL systems are considered as 20ºC walls

Cells Temperature overview Temperature above 30 ºC Temperature above 35 ºC Temperature above 40 ºC This images were taken from the 1.5 times the power case

Summary of Simulation Studies ● In the case of an average power consumption of 1.5W per FE-board, ~0.1% of the cells have a temperature above 35 o C (in M1) ; ~1.2% of the cells have a temperature above 30 o C ; ~11.8% of the cells have a temperature above 25 o C. ● The introduction of cables does not lead to much increased temperatures. ● Since the total power dissipated into the cavern is not really a concern, blowing fresh air into the inner part of the system seems to be sufficient from point of view of cooling. Otherwise some ‘aspiration’ should be foreseen. ● An LHCb note summarizing the results is under preparation.

Cooling for FE-boards: ● The chambers in regions R1 and R2 have up to 24 FE-boards/chamber and hence quite a large power consumption on a small area ->We foresee to have a sort of air cooling, where either the hot air is aspirated directly from the “box” around the chamber, in which the FE-boards are mounted, and cooler air will flow into the “box” (not tight) from the surrounding area. or air of about 17 o C is blown into or around the chambers in R1 and R2 ->Even without this sort of cooling the maximal temperature would be about 65 o C, hence uncritical for the electronics. ● The power consumption of the electronics for the larger chambers in R3 and R4 is less than 10W and no cooling is foreseen. ->We expect that in total about 2/3 (6.5 kW) of the power from the FE will be dissipated and 1/3 (3.5kW) will be cooled Cooling

Example for air-cooling of the FE-boards: Assume that 200W of power have to be cooled per station, and the ΔT we want to cool by air (1kJ/kgK) is 5K. This leads to an airflow Q of 0.04kg/s or (air: 1.2kg/m 3 ): ~33l/s (120m 3 /h) We will have 24 chambers per half-station to be connected to the cooling, so we would have a flow of 5m 3 /h per line. Assuming a tube diameter of 10mm, we get with Q/v=πr 2 (for round tubes) a a velocity for the cooling air of 4.4m/s, which is still ok. ->Careful test would have to be carried out to check that this works. We would count on support from ST/CV... -> A study needs to be done to check that the cooling pipes can be fits into the system space-wise. Air Cooling