1. Fast cooling of interferometer payload
Nomi, istituzioni?
Un po’ di colore
Marco Bazzan, Giacomo Ciani*, Livia Conti, Filippo Martelli, Antonio Perreca, Francesco Piergiovanni, Luca Taffarello, Flavio Travasso, Helios Vocca, Jean-Pierre Zendri

2. The future is cold… and slow
Thermal noise is in the way of exploring the Universe
Many future GW IFO designs foresee cryogenic operations
Room temperature IFO recovery after opening
Dominated by pump-down
Order 1 week
Cryogenic IFOs recovery after opening:
Dominated by cool-down
Order month(s)
Huge impact on commissioning activities and possibly duty cycle!
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

3. Situation even more critical!
The KAGRA case
Vanilla
Diamond Like Coating
Y. Sakakibara et al, 2014 Class. Quantum Grav
Additional thermal links ET
larger masses
thinner and longer fiber
higher circulating laser power?
Situation even more critical!
Y. Sakakibara et al 2014, AIP Conf. Proc :1,
Add details on KAGRA suspension fibers
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

4. Cooling quietly ≠ cooling quickly
Cooling to go in operation and cooling while in operation have conflicting requirements
In operation: avoid vibrations!
To go in operation: cool fast!
Small cooling power sufficient to compensate (mainly) absorption of laser light
Mechanical isolation required:
Long fibers
Small cross/sections
Intermediate isolation stages
Large cooling power required to cool down quickly from room temperature
Seismic isolation irrelevant:
Can use short links
Can use big cross section
No need for intermediate stages
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

5. Divide et impera! Separate and control…
In operation
Before operation
Priority to minimization of vibrations from:
seismic noise
cooling system
Radiative cooldown (boosted by high- emissivity coatings?)
Conduction through thin suspension fibers
Priority to fast cooldown of payload
High-conductivity thermal link to the TM by direct mechanical contact
Short, direct path to (dedicated?) cryostat
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

6. A quite simple idea…
Build a separate device dedicated to initial cooldown, with minimal (zero?) impact on scientific operations
Establish a temporary, strong thermal link to the payload
Use it to quickly extract most of the heat from the TM, until it is close to the operating temperature
Disengage the thermal link and any related mechanical short-circuit, leaving the IFO ready for operation
High power cryostat
Low noise, low power cryostat
Low-temperature shield
Low conductivity,
Quite cooling path
High conductivity cooling path
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

7. …a not so simple implementation
High-conductivity thermal link to the TM without spoiling its mechanical characteristics
Geometry of contact areas?
Material, structure and surface finish of contact pads?
Precise actuation mechanism
Make solid contact with TM
Avoid stresses on the suspension system
Work in vacuum and wide range of temperatures
Active control to compensate for suspension chain drifts
Compatible with GW IFO vacuum requirements
Avoid additional constraints on the already complex design of the suspension system
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

8. The CryoMirror project
Define requirements
Identify and later down-select viable approaches
Build a prototype device
Characterize prototype’s thermal and mechanical performance and impact on payload
Demonstrate its operation on a full-size, plausible payload design
Presented in Summer 2018 in response to a call from INFN group 5 -> Rejected
Large budget (can be reduced)
High engineering character (contacted interested groups with right expertise in Padova, but lack of framework to directly involve them)
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

9. Time is of the essence
The more direct/urgent/definite application of such a device would be in ET
ET is aiming at a technical design in ~2023
CryoMirror development timeline ~ 3 years
The right time to start working on the problem would be… …now!
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

10. Recap In-operation requirements imply:
slow cool-down times
important impact on commissioning and duty cycle
Idea: disentangle the initial and in-operation phases
can significantly reduce cool-down times
Proposal: study and develop a device capable of…
Establishing temporary strong thermal link with payload
Disengaging completely with no impact on scientific operation
Start now to be ready for ET
Currently no funding. Looking for:
General interest
Collaboration opportunities
Funding ideas
Let us know if you are interested and/or have ideas!
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

11. 16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)

12. 16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)
CryoMirror WBS
WP1: definition of requirements and control observables
WP2: development of cryogenic test facility
WP3: development of dummy payload
WP4: development of moveable thermal link prototype
WP5: development of in-loop and out-of-loop sensors
WP6: study/development of contact interface with TM
WP7: Functional test of the prototype
WP8: High-vacuum compatibility
Giacomo Ciani
16-Feb-19, KAGRA-Virgo-3G detectors Workshop (Perugia)