Evaporative CO<sub>2</sub> cooling using microchannels etched in silicon for the future LHCb vertex detector

Nomerotski, A.; Buytart, J; Collins, P.; Dumps, Raphael; Greening, E.; John, M.; Mapelli, A.; Leflat, A.; Li, Y; Romagnoli, Giulia; Verlaat, B.

doi:10.1088/1748-0221/8/04/p04004

Cited by 24 publications

(17 citation statements)

References 7 publications

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“…In order to fulfil this requirement and remove the expected heat load generated by the electronics mounted on the substrate (∼36 W), the novel microchannel cooling technique [9] has been chosen as baseline solution. This solution consists of nineteen 120×200 µm 2 trenches (microchannels) etched in a 260 µm thick wafer, which is then bonded to a cover silicon wafer, thus resulting in the final 400 µm thick silicon substrate.…”

Section: Coolingmentioning

confidence: 99%

The LHCb VELO Upgrade

Capua¹

2017

Proceedings of 38th International Conference on High Energy Physics — PoS(ICHEP2016)

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The upgrade of the LHCb experiment, scheduled for LHC Run-3, will transform the experiment to a triggerless system reading out the full detector at 40 MHz event rate. All data reduction algorithms will be executed in a high-level software farm, enabling the detector to run at luminosities of 2×10 33 cm −2 s −1 . The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current strip detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40 MHz. The upgraded VELO will allow for fast pattern recognition and track reconstruction in the software trigger. The silicon pixel sensors have 55×55 µm 2 pitch, and are read out by the VeloPix ASIC. The VeloPix builds on the currently available Timepix3, modified to deliver a radiation hard design capable of an order of magnitude increase in output rate. The hottest regions will have pixel hit rates of 900 Mhits/s, yielding a total data rate more than 3 Tbit/s for the upgraded VELO. The silicon pixel sensors must be radiation hard to a level of 8×10 15 1MeV n eq cm −2 , delivered non uniformly over the sensor surface. The R&D focusses on designs capable of tolerating high voltage after irradiation and maintaining good efficiency and resolution. The detector modules are located in a secondary vacuum, separated from the beam vacuum by a thin custom made foil. The material budget will be minimised by the use of evaporative CO 2 coolant, circulating in microchannels within 400 µm thick silicon substrates. The current status of the VELO upgrade is described and latest results from the design and prototyping are presented.

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Section: Coolingmentioning

confidence: 99%

The LHCb VELO Upgrade

Capua¹

2017

Proceedings of 38th International Conference on High Energy Physics — PoS(ICHEP2016)

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“…A proof of principle microchannel prototype was produced and CO 2 in a 2-phase stable condition was successfully circulated through it during 2012 [7]. The prototype was made by bonding a 760 µm silicon wafer with the etched channels to a 5 mm Pyrex plate (Fig.…”

Section: Microchannel Studies 31 First Prototypementioning

confidence: 99%

Microchannel evaporative CO2 cooling for the LHCb VELO Upgrade

Pérez¹

2015

Proceedings of Technology and Instrumentation in Particle Physics 2014 — PoS(TIPP2014)

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The LHCb Vertex Detector (VELO) will be upgraded in 2018 to a lightweight pixel detector capable of 40 MHz readout and operation in very close proximity to the LHC beams. The thermal management of the system will be provided by evaporative CO 2 circulating in microchannels embedded within thin silicon plates. This solution has been selected due to the excellent thermal efficiency, the absence of thermal expansion mismatch with silicon ASIC's and sensors, the radiation hardness of CO 2 , and very low contribution to the material budget. Although micro-channel cooling is gaining considerable attention for applications related to microelectronics, it is still a novel technology for particle physics experiments, in particular when combined with evaporative CO 2 cooling. The R&D effort for LHCb is focusing on the design and layout of the channels together with a fluidic connector and its attachment to withstand pressures in excess of 200 bars. This paper will describe the design and optimization of the cooling system for LHCb together with latest prototyping results. Restriction channels are implemented before the entrance to a race-track layout of the main cooling channels. Restriction channels lengths were calculated to have the same total hydraulic resistance in all the channels. The coolant flow and pressure drop has been simulated as well as the thermal performance. These results can be compared to cooling performance measurements on prototype plates operating in vacuum. The design of a suitable low mass connector, together with the bonding technique to the cooling plate will be described. Long term reliability as well as resistance to extremes of pressure and temperature is of prime importance. The setup and operation of a cyclic stress test of the prototype cooling channel designs will be described.

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“…This minimises the thermally induced stress on the module. Tests with heaters glued on a prototype substrate have shown that the heat can be taken out with a temperature difference between heater and coolant of only 7 • C. The nominal operation temperature of the CO 2 is -35 • C and hence the sensor will stay well below the required -20 • C. More information about the microchannel cooling for the LHCb VELO upgrade can be found in [8].…”

Section: Microchannel Coolingmentioning

confidence: 99%

The LHCb Vertex Locator (VELO) Upgrade

Beuzekom¹

2014

Proceedings of 22nd International Workshop on Vertex Detectors — PoS(Vertex2013)

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The upgrade of the LHCb experiment, planned for 2018, will enable the detector to run at a luminosity of 2·10 33 cm −2 s −1 and explore New Physics effects in the beauty and charm sector with unprecedented precision. To achieve this, the entire readout will be transformed into a triggerless system operating at 40 MHz, where the event selection algorithms will be executed by high-level software in the CPU farm. The upgraded silicon vertex detector (VELO) must be lightweight, radiation hard, vacuum compatible, and has to drive data to the data acquisition system at speeds of up to 3 Tbit/s. This challenge will be met with a new VELO design based on hybrid pixel detectors, positioned to within 5 mm of the LHC colliding beams. The sensors have 55 x 55 µm 2 square pixels and the VeloPix ASIC, which is being developed for the readout, is based on the Timepix/Medipix family of chips. The hottest ASIC will have to cope with integrated hit rates of up to 900 MHz which translates to a bandwidth of more than 15 Gbit/s. Work is in progress to optimise the sensor guard ring design to cope with the irradiation levels, which are highly non-uniform and reach 8·10 15 1 MeV n eq cm −2 at the innermost region. The material budget is optimised with the use of evaporative CO 2 coolant circulating in microchannels within a thin silicon substrate. Microchannel cooling brings many advantages: very efficient heat transfer with almost no temperature gradients across the module, no CTE mismatch with silicon components, and a small contribution to the material budget. LHCb is also focussing effort on the construction of a lightweight foil to separate the primary and secondary LHC vacua, the development of high-speed data acquisition boards, and the radiation qualification of the pixel detector modules.

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Evaporative CO₂ cooling using microchannels etched in silicon for the future LHCb vertex detector

Cited by 24 publications

References 7 publications

The LHCb VELO Upgrade

The LHCb VELO Upgrade

Microchannel evaporative CO2 cooling for the LHCb VELO Upgrade

The LHCb Vertex Locator (VELO) Upgrade

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Evaporative CO2 cooling using microchannels etched in silicon for the future LHCb vertex detector

Cited by 24 publications

References 7 publications

The LHCb VELO Upgrade

The LHCb VELO Upgrade

Microchannel evaporative CO2 cooling for the LHCb VELO Upgrade

The LHCb Vertex Locator (VELO) Upgrade

Contact Info

Product

Resources

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Evaporative CO₂ cooling using microchannels etched in silicon for the future LHCb vertex detector