Development of a blue-mirror multilayer coating on light concentrators for future SiPM cameras

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378271%3A90247%2F24%3A00643274" target="_blank" >RIV/68378271:90247/24:00643274 - isvavai.cz</a>

Result on the web

<a href="https://pos.sissa.it/444/673/pdf" target="_blank" >https://pos.sissa.it/444/673/pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.22323/1.444.0673" target="_blank" >10.22323/1.444.0673</a>

Result language

angličtina

Original language name

Development of a blue-mirror multilayer coating on light concentrators for future SiPM cameras

Original language description

Silicon photomultipliers (SiPMs) have a few advantages over conventional photomultiplier tubes (PMTs) used in imaging atmospheric Cherenkov telescopes. The first notable characteristic is their higher photon detection efficiency (PDE) of up to about 60%, which is roughly 1.2–1.5 times better than that of PMTs in the 300–450 nm range, enabling us to lower the energy threshold of gamma-ray observations and increase the photon statistics. The second advantage is that SiPMs are chemically stable after exposure to long and bright illumination, while PMTs can cause gain and quantum efficiency degradation after the same exposure. Therefore, the use of SiPMs under bright or full moon conditions may extend the total observation time in the highest energy coverage region of individual telescopes. However, the SiPM PDE is too high in wavelengths longer than 500 nm, hence, the signal-to-noise ratio (S/N) of the Cherenkov signal over the night-sky background (NSB) is not necessarily superb. This is because the Cherenkov signal is dominant over the wavelength of 300–500 nm, while the NSB is brighter in the region of 550 nm or longer. To improve the S/N with minimal and cost-effective additional hardware, we have developed multilayer coating designs with only 8 layers and applied them to the specular surfaces of light concentrators. The layers were designed to reflect more photons in the 300–500 nm range but fewer in 550–800 nm. Using a prototype light concentrator fabricated with the novel multilayer design, we demonstrated that a SiPM array exhibits ∼50% better photon collection efficiency at 403 nm than that obtained with PMTs, agreeing with the result of a ray-tracing simulation. The efficiency measured at 830 nm was also successfully reduced by 30–50%.

Czech name

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Czech description

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Type

D - Article in proceedings

CEP classification

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OECD FORD branch

10303 - Particles and field physics

Project

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Continuities

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Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Article name in the collection

Proceedings of Science

ISBN

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ISSN

1824-8039

e-ISSN

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Number of pages

8

Pages from-to

673

Publisher name

Sissa Medilab srl

Place of publication

Trieste

Event location

Nagoya

Event date

Jul 26, 2023

Type of event by nationality

WRD - Celosvětová akce

UT code for WoS article

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