Characterization of the PArametric COnverter detector Ilias Task M3 “Investigation Of Superconducting Materials”

Renzo Parodi INFN-Genoa Task Aim Development of an innovative detector based on superconducting resonant cavities suitable for High Frequency Gravitational Waves (5-10Khz) Proof of feasibility of the detector to ascertain the feasibility of the development of advanced superconducting RF detectors with high sensitivity. ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Renzo Parodi INFN-Genoa Detector’s Basics 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 f1 and f2. One of the modes is fed with RF power Pin [watt] A gravitational wave of amplitude h deforms the cavities: when the G-Wave frequency W matches the frequency difference between the two modes W=(f2 -f1), a maximum RF energy transfer between the two modes occurs (parametric conversion) with output power Pout~h2PinQel 2 [watt] The detector is Tunable 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 mass. ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Renzo Parodi INFN-Genoa Prototype detector A detector (inner radius of Niobium spherical cell ~0.1 m, thickness 2 mm) is designed and built. The foreseen sensitivity is ~10-19 for a detector having the following parameters: overall mass M ~ 4 kg RF frequency ~ 2 GHz, stored energy U ~ 10 J, detection frequency range: 5 kHz < Fgw < 20 kHz. ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Prototype construction The cavity was built using the procedure established along the Task M3 using the tooling developed for the construction of the cavity mock-up The prototype was delivered to the Genoa-INFN lab on October 16, 2006 Test started January 2007 . ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Renzo Parodi INFN-Genoa Rf Charecterization The Prototype was tested for the RF parameters in the Standard parallel Cryostat. To reduce to a minimum the RF a Cryoperm ® magnetic shield was used. The measured unloaded RF Quality factor was 4.7×1010 at a surface RF magnetic field of 56 mT, corresponding to 10J of stored energy, exceeding by a factor 4 the design Goal ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Magnetic field (Gauss) RF Results Paco Cavity Magnetic field (Gauss) QL factor Q0 factor (b 13) 35 5.5×109 7.7×1010 260 4.5×109 6.3×1010 560 3.4×109 4.7×1010 ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

PaCo Detector RF System Lock the the master RF oscillator to the resonant frequency of the cavity Drive the coupled resonators purely in the symmetric mode and receive only the RF power up–converted by the perturbation of the cavity walls to the antisymmetric mode. Cancel the contribution to the output of the detector produced either by the drive RF signal and by the common mode mechanical perturbation of the cavity walls. ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Sensitivity enhancement RF System ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Renzo Parodi INFN-Genoa Results Using the prototype cavity @4.2K Parametric conversion Frequency ~7 Khz 100mm radius 4Kg Qem ~ 3x109 (4.2 K) Stored energy U~1 Joule Quad Mechanical mode frequency~4KHz Qmec ~ 103 ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Renzo Parodi INFN-Genoa Results (Continued) We get the signal reported for .1 V peak sinusoidal signal applied to the drive piezos. Using a Room temperature low noise amplifier with 350K Noise temperature (0.6 dB Noise Figure) ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Renzo Parodi INFN-Genoa Detector Output The demodulated Output of the PArametric COnverter operated at 4.2 K is reported The conversion signal at the W=f2-f1 Frequency is clearly seen ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Renzo Parodi INFN-Genoa Detector sensitivity The plot of the output of the PACO detector for 5 Volts Peak and 0 volt (no Drive) sinusoidal drive of the piezo are reported The estimated strain sensitivity at 4.2 kelvin is shown on the same plot ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

Renzo Parodi INFN-Genoa Conclusions The Prototype of the PArametric COnverter detector is now Running at the design sensitivity as planned, without unforeseen surprises. The construction thecnique chosen was proven adequate. A suitable cavity manufacturer is selected and a second alternate supplier was still found. ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa

The PACO Group INFN Genoa Renzo Ballantini Philippe Bernard Renzo Parodi Emilio Picasso Renzo Vaccarone ILIAS-ET GW meeting EGO24-11-2008 Renzo Parodi INFN-Genoa