Description
MAD: Substrates
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Jessica Steinlechner06/10/2025, 12:30Talk
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Severin Nadji (Laboratoire des Matériaux Avancés (LMA))06/10/2025, 12:45Talk
In Lyon, we are investigating the potential of using sapphire mirrors for the Einstein Telescope Low-Frequency (ET-LF) detector. Compared to silicon, sapphire offers several advantages in cryogenic environments. These include superior thermal conductivity, higher density and optical transparency across the visible and the near infrared spectrum. Although KAGRA currently uses sapphire test...
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Dr Sune Duun (Topsil GlobalWafers A/S)06/10/2025, 13:00Talk
The Float-Zone (FZ) method is the only industrially established technique for producing large silicon crystals of ultrahigh purity. The resulting low absorption at 1550 nm makes FZ silicon a strong candidate for cryogenic mirror substrates in next-generation gravitational wave detectors such as the Einstein Telescope (ET). Absorption levels below 10 ppm/cm have been measured in crystals grown...
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Frank Kiessling (Leibniz-Institut für Kristallzüchtung)06/10/2025, 13:15Talk
The Einstein Telescope (ET) is a future 3rd generation gravitational wave observatory in Europe and crystalline silicon is under investigation to be used for mirrors. For the semi-transparent ET interferometer mirrors, large Si crystals [1] with ultrahigh purity are needed to minimize thermal noise (low laser light absorption and mechanical loss).
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The defect structure and purity of the volume... -
Guido Alex Iandolo06/10/2025, 14:30Talk
Mechanical characterization of silicon for the ETpathfinder test masses
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Nathan Stoddard (Lehigh University)06/10/2025, 14:45Talk
The NeoGrowth method, originally developed for high-efficiency photovoltaics, is a crucible-free crystal growth technique with promising potential for producing cryogenic mirror substrates for next-generation gravitational wave detectors such as the Einstein Telescope (ET). Crystal diameters of 450 mm—within the required range for ET—have already been demonstrated. The method enables oxygen...
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Dr Robert Menzel06/10/2025, 15:00Talk
Third-generation gravitational wave detectors operating at cryogenic temperatures, such as the Einstein Telescope, require silicon mirror substrates with both exceptional purity and large diameter (>450 mm). The float-zone (FZ) method enables the growth of ultra-high purity silicon crystals but is limited in diameter beyond 200 mm. The Czochralski (Cz) method allows larger diameters but...
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Dr Margot Hennig06/10/2025, 15:15Talk
The success of the next generation of ground based GW detectors will require large diameter test mass optics that can be operated at cryogenic temperatures. Silicon test masses of >45cm diameter, and 100-200kg are the leading contenders for mirror substrate material, however currently there is no one who can provide silicon of the required high quality and large diameter that is needed....
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Aaron Goodwin-Jones (UCLouvain)06/10/2025, 15:30Talk
The use of composite silicon substrates — assembled from multiple bonded components — offers a practical path to realising large test masses for the Einstein Telescope Low-Frequency (ET-LF) interferometer, while relaxing constraints on boule diameter and availability. However, these designs introduce bond lines across the optical aperture, which are expected to exhibit excess absorption and...
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Jessica Steinlechner, Laura Silenzi06/10/2025, 15:45Talk
Due to a very low mechanical loss, resulting in low thermal noise, crystalline silicon is a very interesting mirror-substrate material for future cryogenic gravitational-wave detectors.
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To maintain the low detector operation temperature, low optical absorption of the mirrors is required. This requirement includes all components of the mirrors, i.e. the mirror substrates as well as the...