Thermal noise from icy mirrors in gravitational wave detectors

Steinlechner, J.; Martin, I. W.

doi:10.1103/physrevresearch.1.013008

Cited by 10 publications

(5 citation statements)

References 41 publications

(67 reference statements)

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“…The ice thickness could have exceeded 2 µm, but a quantitative analysis is considered difficult. Hasegawa et al (2019), Steinlechner & Martin (2019), Tanioka et al (2020), andSpallino et al (2021), KAGRA: The Kamioka Gravitational Wave Detector uses cryogenic mirrors in a vacuum for enhanced sensitivity, and thus experiences the same contamination problems from outgassing as spacecraft. Quast et al (2019) and Decoster et al (2013), Meteosat: The visible channel onboard the Meteosat First Generation (MFG) Meteosat-7 lost 20-30% of its spectral transmission in the 450-900 nm band between 1997 and 2017.…”

Section: Appendix A: Non-exhaustive List Of Publications About Contam...mentioning

confidence: 99%

Euclid preparation

Schirmer¹,

al.²

2023

A&A

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Material outgassing in a vacuum leads to molecular contamination, a well-known problem in spaceflight. Water is the most common contaminant in cryogenic spacecraft, altering numerous properties of optical systems. Too much ice means that Euclid’s calibration requirements cannot be met anymore. Euclid must then be thermally decontaminated, which is a month-long risky operation. We need to understand how ice affects our data to build adequate calibration and survey plans. A comprehensive analysis in the context of an astrophysical space survey has not been done before. In this paper we look at other spacecraft with well-documented outgassing records. We then review the formation of thin ice films, and find that for Euclid a mix of amorphous and crystalline ices is expected. Their surface topography – and thus optical properties – depend on the competing energetic needs of the substrate-water and the water-water interfaces, and they are hard to predict with current theories. We illustrate that with scanning-tunnelling and atomic-force microscope images of thin ice films. Sophisticated tools exist to compute contamination rates, and we must understand their underlying physical principles and uncertainties. We find considerable knowledge errors on the diffusion and sublimation coefficients, limiting the accuracy of outgassing estimates. We developed a water transport model to compute contamination rates in Euclid, and find agreement with industry estimates within the uncertainties. Tests of the Euclid flight hardware in space simulators did not pick up significant contamination signals, but they were also not geared towards this purpose; our in-flight calibration observations will be much more sensitive. To derive a calibration and decontamination strategy, we need to understand the link between the amount of ice in the optics and its effect on the data. There is little research about this, possibly because other spacecraft can decontaminate more easily, quenching the need for a deeper understanding. In our second paper, we quantify the impact of iced optics on Euclid’s data.

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Section: Appendix A: Non-exhaustive List Of Publications About Contam...mentioning

confidence: 99%

Euclid preparation

Schirmer¹,

al.²

2023

A&A

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“…In order to evaluate the impact of the CML, we need several assumptions. First, we assume that the CML is composed of water as the previous works did [17,18]. In addition, the water molecular layer is formed as amorphous ice [29].…”

Section: Implication To Experimentsmentioning

confidence: 99%

“…The change in mirror properties can increase the noise level related to the beam power [17]. Moreover, the thermal noise induced by the CML can become a limiting noise source in ET [18]. Thus, the sensitivity of cryogenic GWDs can be deteriorated by the CML formation.…”

Section: Introductionmentioning

confidence: 99%

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The optical loss study of molecular layer for a cryogenic interferometric gravitational-wave detector

Tanioka,

Hasegawa,

Aso

2020

Preprint

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The detection of gravitational-waves provides us with a deep insight into the universe. In order to increase the number of detectable gravitational-wave sources, several future gravitational-wave detectors will operate with cryogenic mirrors. Recent studies, however, showed residual gas molecules inside the vacuum chamber adhere to the cryogenic mirror surface and form a molecular layer which grows with time. The growing molecular layer introduces an additional optical loss in the mirror which can decrease the detector's performance. We theoretically estimate the optical loss by the molecular layer in a cryogenically operated gravitational-wave detector. The impacts on a cryogenic gravitational-wave detector is discussed based on the results of optical loss estimation.

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“…This overlayer, which is predominantly composed of water ice, adds an undesired contribution to the optical absorption of the coatings forming the mirrors, and affects their reflectivity. For instance KAGRA, the most recently-built GWD, has been reported to suffer from a loss of performance due to the progressive growth of an ice layer on the surface of its main mirrors [5][6][7]. Given the characteristics of GWD, such as the very large volume of the chambers that host the main mirrors, it is unlikely that the issue of icing can be completely avoided [8], at least with passive methods.…”

Section: Introductionmentioning

confidence: 99%

Detecting ultrathin ice on materials for optical coatings at cryogenic temperatures

Magnozzi,

Bisio,

Gemme

et al. 2023

J. Phys. D: Appl. Phys.

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The performance of optical cavities in Gravitational Wave Detectors (GWD) is negatively affected by the growth of ice layers when operating at cryo temperatures. Loss of performance begins when the ice overlayer is only a few-nm thick. Careful planning is then required to minimize, monitor and take into account the presence of ultrathin ice on cryo-cooled optical surfaces. Here we employed spectroscopic ellipsometry (SE) to study icing on the surfaces of SiO2 and Ti:Ta2O5 thin films, two materials used in the high-reflective mirrors of current GWD. SE measurements were performed at 75 K. The data presented suggest that SE is a most convenienttool to monitor in operando the ice formation on the surfaces of GWD mirrors.Furthermore, ultrathin ice layers can affect the evaluation of the optical properties of materials at low temperatures, a valuable task for those next-generation GWD that will operate at cryogenic temperatures. The characterization of an ultrathin ice overlayer (<10 nm) allowed to determine for the first time the low-temperature optical properties of Ti:Ta2O5. The same approach could be applied to determine the low-temperature optical properties of other dielectric films, thus helping to screen new materials for cryo-operated GWD mirrors.

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Thermal noise from icy mirrors in gravitational wave detectors

Cited by 10 publications

References 41 publications

Euclid preparation

Euclid preparation

The optical loss study of molecular layer for a cryogenic interferometric gravitational-wave detector

Detecting ultrathin ice on materials for optical coatings at cryogenic temperatures

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