WP-M3 Superconducting Materials PArametric COnverter Detector INFN_Genoa Renzo Parodi

2 An innovative tunable detector based on superconducting resonant RF cavities is proposed. An innovative tunable detector based on superconducting resonant RF cavities is proposed. The weak electromagnetic (EM) coupling between two equal RF cavities gives two RF Resonant Modes (symmetric and anti- symmetric in the fields) at slightly different frequencies f 1 and f 2.. The weak electromagnetic (EM) coupling between two equal RF cavities gives two RF Resonant Modes (symmetric and anti- symmetric in the fields) at slightly different frequencies f 1 and f 2.. One of the modes is fed with RF power P in [watt] One of the modes is fed with RF power P in [watt] The key feature of the system is the High (~10 11 ) Electromagnetic Quality Factor Q el of the cavities The key feature of the system is the High (~10 11 ) Electromagnetic Quality Factor Q el of the cavities The detector – tuning system

3 The Electromagnetic behaviour The mechanical interaction with the G-Wave.

4 A gravitational wave of amplitude h deforms the cavities: A gravitational wave of amplitude h deforms the cavities: When the G-Wave frequency  matches the frequency difference between the two modes  =(f 2 -f 1 ), a maximum RF energy transfer between the two modes occurs, (parametric conversion) When the G-Wave frequency  matches the frequency difference between the two modes  =(f 2 -f 1 ), a maximum RF energy transfer between the two modes occurs, (parametric conversion) with output power with output power P out ~h 2 P in Q el 2 [watt]

5 Two pill-box niobium cavities mounted end-to-end and coupled through a small aperture on the axis Working frequency  3 GHz Mode splitting  500 kHz 2  K Quality factor (e.m.) 2  K 1.8 J Stored energy 1.8 J dL/L~ Hz 500 KHz Two piezoelectric crystals A and B mounted on the end walls are used to simulate the g.w. Effects. A B The feasibility study results

6 Starting from the small-scale prototype experience, a detector (inner radius of Niobium spherical cell ~0.2 m, thickness 5 mm) could be designed and built. The foreseen sensitivity is ~ for a detector having the following parameters: –overall mass M ~ 45 kg –RF frequencie ~ 1 GHz, –stored energy U ~ 200 J, –detection frequency range: 2 kHz < F gw < 10 kHz.

Frequency [Hz] S hh (1/2) [Hz] (-1/2) h min  6 x h < over 400 Hz

8 Main Outcomes The new detection method, based on Radio Frequency cavities, is further developed to build a fully operational gravitational wave detector. The new detection method, based on Radio Frequency cavities, is further developed to build a fully operational gravitational wave detector. Superconducting RF cavities may be also used as transducers in the resonant detectors, as well in the selective read-out schemes. Superconducting RF cavities may be also used as transducers in the resonant detectors, as well in the selective read-out schemes. The use of Niobium coated cavities will allow for a wide choice of materials (with High Mechanical Quality factor) and Refrigeration schemes, keeping to a minimum the cavity-coolant interaction and the coolant (LHe) inventory. The use of Niobium coated cavities will allow for a wide choice of materials (with High Mechanical Quality factor) and Refrigeration schemes, keeping to a minimum the cavity-coolant interaction and the coolant (LHe) inventory. This last point will be beneficial in improving the detector sensitivity, further reducing the noise contribution of the cavity wall Thermal Fluctuations This last point will be beneficial in improving the detector sensitivity, further reducing the noise contribution of the cavity wall Thermal Fluctuations

9 Modified Facilities Helium liquefier and equipment for cryogenic tests in the temperature range K Helium liquefier and equipment for cryogenic tests in the temperature range K RF test set-up in the frequency range 50 MHz – 20 GHz for materials and RF components RF test set-up in the frequency range 50 MHz – 20 GHz for materials and RF components Design Tools and test set-up for Superconducting (S/C) RF cavities Design Tools and test set-up for Superconducting (S/C) RF cavities

10 An innovative detector based on High (~10 11 ) electromagnetic Quality Factor Q el superconducting resonant RF cavities has been proposed An innovative detector based on High (~10 11 ) electromagnetic Quality Factor Q el superconducting resonant RF cavities has been proposed The weak electromagnetic (EM) coupling between two equal RF cavities generates two Resonant Modes (symmetric and anti-symmetric on the fields) at slightly different frequencies f 1 and f 2.. One of the modes is fed with RF power P in [watt] The weak electromagnetic (EM) coupling between two equal RF cavities generates two Resonant Modes (symmetric and anti-symmetric on the fields) at slightly different frequencies f 1 and f 2.. One of the modes is fed with RF power P in [watt] A gravitational wave of amplitude h deforms the cavities: when the G- Wave frequency  matches the frequency difference between the two modes  =(f 2 -f 1 ), a maximum RF energy transfer between the two modes occurs (parametric conversion) with output power A gravitational wave of amplitude h deforms the cavities: when the G- Wave frequency  matches the frequency difference between the two modes  =(f 2 -f 1 ), a maximum RF energy transfer between the two modes occurs (parametric conversion) with output power P out ~h 2 P in Q el 2 [watt] The detector is Tuneable with constant sensitivity on a quite broad range of frequencies (~2-10KHz) by changing the RF coupling of the cavities not the cavity dimensions or masses. The detector is Tuneable with constant sensitivity on a quite broad range of frequencies (~2-10KHz) by changing the RF coupling of the cavities not the cavity dimensions or masses.