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Integration of thermo-electric coolers into the CMS MTD SiPM arrays for operation under high neutron fluence
Ist Teil von
Journal of instrumentation, 2023-08, Vol.18 (8), p.P08020
Ort / Verlag
Bristol: IOP Publishing
Erscheinungsjahr
2023
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Abstract
The barrel section of the novel MIP Timing Detector (MTD)
will be constructed as part of the upgrade of the CMS experiment to
provide a time resolution for single charged tracks in the range of
30–60 ps using LYSO:Ce crystal arrays read out with
Silicon Photomultipliers (SiPMs). A major challenge for the
operation of such a detector is the extremely high radiation level,
of about 2 × 10
14
1 MeV(Si) Eqv. n/cm
2
, that will be
integrated over a decade of operation of the High Luminosity Large
Hadron Collider (HL-LHC). Silicon Photomultipliers exposed to
this level of radiation have shown a strong increase in dark count
rate and radiation damage effects that also impact their gain and
photon detection efficiency. For this reason during operations the
whole detector is cooled down to about -35°C. In this
paper we illustrate an innovative and cost-effective solution to
mitigate the impact of radiation damage on the timing performance of
the detector, by integrating small thermo-electric coolers (TECs) on
the back of the SiPM package. This additional feature, fully
integrated as part of the SiPM array, enables a further decrease in
operating temperature down to about -45°C. This leads to a
reduction by a factor of about two in the dark count rate without
requiring additional power budget, since the power required by the
TEC is almost entirely offset by a decrease in the power required
for the SiPM operation due to leakage current. In addition, the
operation of the TECs with reversed polarity during technical stops
of the accelerator can raise the temperature of the SiPMs up to
60°C (about 50°C higher than the rest of the
detector), thus accelerating the annealing of radiation damage
effects and partly recovering the SiPM performance.