GRAvitational-waves Science&technology Symposium (GRASS 2024)

Session

Coating and Materials

CTMT

30 Sept 2024, 13:50

Aula Kessler

46. Mirror coatings for next-generation detectors: what do we need

François Schiettekatte (Université de Montréal)

30/09/2024, 13:50

Coatings and Materials

Invited talk

US-based next-generation gravitational wave detectors can currently be divided in two implementations: A# will feature 100 kg test masses and should operate at room temperature (RT), while Cosmic Explorer (CE) should feature even 320 kg test masses, and laser power reaching 1.5 MW in the arms, with its first incarnation operating at RT. In the former, sensitivity limits in the most sensitive...

2. Mirrors Design for Future Gravitational-Wave Detectors

Alex Amato (Maastricht University - Nikhef)

30/09/2024, 14:20

Coatings and Materials

Contributed talk

Alex Amato, on behalf of the GWFP group of Maastricht University.

While current gravitational-wave detectors allow for successful detections, there is a need to increase their sensitivity by trying to enlarge their frequency band to observe additional types of gravitational waves sources. Future cryogenic detectors such as the Einstein Telescope aim for this improvement. Improved operating...

45. Reduction of mirror coating thermal noise via thermal treatment and material optimization.

Dr Valeria Milotti (University of Padova, INFN PD)

30/09/2024, 14:40

Coatings and Materials

Contributed talk

Reducing coating thermal noise (CTN) in mirrors for gravitational wave (GW) interferometers is pivotal to improve sensitivity in the mid-frequency range. Mirror coatings are Bragg’s mirrors alternating between high and low refractive index layers.
Commonly, amorphous coatings are heat-treated post-deposition in order to both reduce their internal strains and improve their optical quality....

15. Real-time monitoring of thermal annealing as a tool to enhance the properties of coatings for GWD mirrors.

Michele Magnozzi (Istituto Nazionale di Fisica Nucleare), Ms Shima Samandari (Università di Genova)

30/09/2024, 15:00

Coatings and Materials

Contributed talk

Enhancing the performance of GWD mirrors is a complex endeavor which entails several key steps, including the selection of a suitable mirror design, the choice of the most appropriate chemical composition of coatings and the protocol for post-deposition treatments – i.e., thermal annealing.
During more than two decades of continuous research and development [1,2], a lot of effort has been...

18. Raman spectra of $a$-Ta$_2$O$_5$: a first-principles analysis

Luigi Giacomazzi (CNR - Istituto Officina dei Materiali (IOM))

30/09/2024, 15:20

Coatings and Materials

Contributed talk

We present a first-principles study of the vibrational spectra, i.e. vibrational density of states ($v$-DOS), infrared (IR), and Raman spectra, in amorphous tantala ($a$-Ta$_2$O$_5$). Model structures of upto three-hundreds atoms have been generated by means of classical and ab-initio molecular dynamics. An unprecedented series of ab-initio test calculations of the $v$-DOS and the IR...

38. Characterization of Amorphous Silica Coatings for Gravitational Wave Detectors: A Multitechnique Spectroscopic Approach

Bracco Brenda (Department of Chemistry, Biology and Biotechnology, University of Perugia and Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Perugia, Italy)

30/09/2024, 15:40

Coatings and Materials

Contributed talk

Amorphous silica coatings play a crucial role as mirror components in gravitational wave detectors, such as those used in the Virgo experiment at the European Observatory in Cascina (PI, Italy). Exceptionally high sensitivity is required for the detection of gravitational waves and thermal noise from mirror coatings is one of the main limiting factors in the spectral region where the detector...

17. Molecular dynamics study of the formation of porous films by room-temperature physical vapor deposition of silica

Prof. Anael Lemaitre (Laboratoire Navier -- ENPC)

30/09/2024, 16:30

Coatings and Materials

Contributed talk

Low-temperature physical vapor deposition is studied by means of molecular dynamics (MD) simulations using the reactive force field (ReaxFF) potential. In contrast with prior MD studies of this process, which employed non-reactive, rigid ion force fields, our approach allows for accurate modeling of the reactive incorporation of impinging particles, generated by the vaporization process, into...

37. Internal friction of silica membranes at high frequencies

Giacomo Baldi (Istituto Nazionale di Fisica Nucleare)

30/09/2024, 16:50

Coatings and Materials

Contributed talk

Knowledge of the frequency-dependence of the acoustic attenuation in structural glasses is necessary to understand their universal low temperature thermal properties. However, very little experimental information is currently available on the vibrational properties of glasses in the frequency range between 100 GHz and 1 THz, corresponding to the temperature range relevant for these thermal...

44. Measuring coating loss angle in thermoelsatic-dominated crystalline substrates for new generation gravitational wave detectors

Federica Fabrizi (Istituto Nazionale di Fisica Nucleare)

30/09/2024, 17:10

Coatings and Materials

Contributed talk

Coatings of materials with low optical and mechanical losses find prominent application in present terrestrial interferometric gravitational-wave detectors. The mirrors of the interferometers currently consist of fused silica substrates coated with stacks of alternating layers of amorphous silica and titania-tantala mixing. Research and development of novel materials is very active, since a...

8. Investigating Crystalline Corundum Coatings for Low-Noise Cryogenic Interferometers

Alberto Binetti (KU Leuven)

30/09/2024, 17:30

Coatings and Materials

Contributed talk

To further reduce the mirror coating thermal noise for the Einstein Telescope (ET) and other third-generation gravitational wave detectors, a substantial improvement in the coating technology and material is necessary. Employing crystalline coatings is one of the new promising directions of the scientific endeavor to replace SiO₂ and Ti:Ta₂O₅ for...

42. Development of femtoAmpere photo-current measurement facility in preparation of LISA Charge Management System end-to-end discharge test

Francesco Venturelli (UniTN/INFN-TIFPA)

30/09/2024, 17:50

Coatings and Materials

Contributed talk

We are developing and tuning a facility to support the end-to-end discharge test campaign, part of the LISA Gravitational Reference System(GRS) test campaign, which probes directly the photo-current produced by UV illumination of the Test Mass and Electrode Housing via an electrometer. LISA Test Masses will be subject to collisions from charged space particles with energies >100 MeV, which...

34. Surface properties of gold coated surfaces used in the discharge system of LISA.

Teodoro Klaser (Università degli studi di Trento)

30/09/2024, 18:10

Coatings and Materials

Contributed talk

LISA will integrate in the gravitational reference system (GRS) an ultra‐violet (UV) illumination device that will avoid excessive charge build-up on the test masses (TM) by producing appropriate photoelectron currents.
The properties of the gold-coated surfaces of the TM, and of the electrode housing that surrounds it, play a crucial role in determining the performance of this discharge...

9. Growth of monocrystalline silicon fibers for mirror suspension in gravitational-wave detectors

Dr Iryna Buchovska (Leibniz-Institut für Kristallzüchtung)

30/09/2024, 18:30

Other challenges for future GW detectors

Contributed talk

Monocrystalline silicon fibers are a promising candidate to be used in gravitational-wave detectors for suspension of silicon test masses. High thermal conductivity and mechanical quality factor Q, very low thermal expansion coefficient, large strength-to-weight factor and compatibility with test masses enable stable support of heavy silicon mirrors and effective extraction of laser beam heat...