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PRELIMINARY DATA ON THE COATING AT THE LIQUID NITROGEN TEMPERATURE

PRELIMINARY DATA ON THE COATING AT THE LIQUID NITROGEN TEMPERATURE. Flavio Travasso Virgo-Perugia Group. Samples. TiO 2 /SiO 2 caoted slab (50 layers evaporated by SILO) (Measured) TiO 2 doped Ta 2 O 5 coated slab (Sputtering by LMA) (Work in progress)

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PRELIMINARY DATA ON THE COATING AT THE LIQUID NITROGEN TEMPERATURE

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  1. PRELIMINARY DATA ON THE COATING AT THE LIQUID NITROGEN TEMPERATURE Flavio Travasso Virgo-Perugia Group

  2. Samples • TiO2/SiO2 caoted slab (50 layers evaporated by SILO) (Measured) • TiO2 doped Ta2O5 coated slab (Sputtering by LMA) (Work in progress) • Co doped Ta2O5 coated slab (Sputtering by LMA) (Next months) • Uncoated fused silica (311) slab supplied by LMA (Next months) • Dimension of the slabs: • Silo TiO2/SiO2: 25mm x 25mm x 50 μm with a coating of 5 μm • LMA doped samples: 5mm x 41mm x 104 μm with a coating of about 5 μm

  3. Labview Interface Ni Ni He He He Cu HV Amplifier Clamp tightened using a spring Laser

  4. Preliminary data: TiO2/SiO2 coating • Loss angle vs. Temperature: coated and uncoated sample have a minimum at about 160K • The trend of the coated sample seems to be driven by the behaviour of substrate of fused sillica • Levin model (using a FEM model): we need a good database about the thermal trend of ETiO2 (loss angle of the coating at room temperature is about 10-3) The silica has a peak at the lower temperature…maybe we are seeing the first part (?) CoatedSample UncoatedSample

  5. Preliminary data: TiO2-doped Ta2O5 coating (1) • Coated sample:same trend of the TiO2/SiO2 coated sample • Uncoated sample: work in progress Work done in collaboration with LMA/Virgo laboratory

  6. Preliminary data: TiO2-doped Ta2O5 coating (2) • Increasing of the loss angle decreasing the temperature • The loss angle seems to be frequency dependent: we need much more data to increase the statistics

  7. Temperature hysteresis The dispersion of the data and the value of the ΦTot have a minimum around 160K cooling down and aroud 120K warming up Cool down Warm up

  8. Labview Interface Ni Ni He He He Cu Open problem • Short term upgrade: change present clamp • New suspension system: MIT like • Thermalization of the sample: moving contact, gas of He inside the chamber(?) • Reading of the temperature: twin system • Long term upgrade • Pulse tube: evaluation of the noise Laser

  9. Summary • Trend of the data versus the temperature maybe driven by the substrate • Frequency dependency of the loss angle at temperature lower than 160K • Need to improve the system: short and long term upgrades

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