April 27th, 2006 Paola Puppo – INFN Roma ILIAS Cryogenic payloads and cooling systems (towards a third generation interferometer) part II: the Vibration Free Cryostat and the Cryogenic Mini-Payload Paola Puppo I.N.F.N. Sezione di Roma

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Refrigeration system study : The Vibration Free Cryostat (V.F.C.)  Thermal behavior;  Cryogenic Instrumentation for the monitor and control  displacement sensor (low frequency)  cryogenic accelerometers (high frequency)  Results on the vibration control Cryogenic small scale payload made of silicon: Assembly test

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Refrigeration system study: The cryogenic facility: Vibration Free Cryostat (V.F.C.)

April 27th, 2006 Paola Puppo – INFN Roma ILIAS The Vibration Free Cryostat: principle scheme The Vibration Free Cryostat: principle scheme V.F.C. Spring Active vibrational isolation system for the heat link Þ Shorter heat link Þ Refrigerating power preserved It is necessary to monitor the vibration at low temperature and to act on the refrigerator: Accelerometers and position sensing devices; Accelerometers and position sensing devices; Actuators; Actuators;

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Sumitomo cryocooler Cooling capacity 1st stage 45 K (50/60 Hz) 2nd stage 4.2 K (50/60 Hz) Lowest temperature < 3 K

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Vibration Free Cryostat:

April 27th, 2006 Paola Puppo – INFN Roma ILIAS The jelly fish thermal contact The special bellow The piezo actuator Vibration Free Cryostat: details

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Current status Thermal behavior of the system (FEM and data); Mechanical noise characterization completed; PT Refrigeration system : set up of the vibration compensation system; Mechanical transfer function measurements; Control of the pulse tube induced vibrations;

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Thermal FEM simulation Cold Stage 1 Cold Stage 2

April 27th, 2006 Paola Puppo – INFN Roma ILIASResults The results are used to evaluate the thermal powers extracted at the cold stages points.

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Noise characterization: Low Frequency noise Low Frequency noise High Frequency noise High Frequency noise Results: Two orders of magnitude gained at frequencies grater than 100 Hz Setup: 1 Accelerometer placed on the cold head 1 Accelerometer on the top of the vacuum chamber

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Position sensor : the optical fiber bundle Measurement set-up Material: optran silica for broad temperature range Protection: PVC or s.s. Laser source : 638 nm (red) Target: polished surface Target Laser Photodiode

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Vertical Noise measurements The optical sensor is sensitive in the low frequency range and it is used as the readout of the control system.

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Vertical Tranfer function Measurements Exciting source: piezo actuators Sensor: optical sensor on the II stage

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Preliminary results of VFC (no payload in the inner chamber): Cooling down OK; Vertical control monitoring the cold head OK (position sensing); Study of all the mechanical couplings inside the VFC. INFN-Roma, Preliminary results of VFC (no payload in the inner chamber): Cooling down OK; Vertical control monitoring the cold head OK (position sensing); Study of all the mechanical couplings inside the VFC.

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Outer tank mode excited by the control system and visible on the cold head residual motion when the control loop is closed; Such a coupling can be removed by modifying the mechanical set up both of the optical readout and of the outer tank;

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Cryogenic reduced scale silicon payload

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Mini payload made of silicon: 1/3.5 scaled Si Copper insert in the silicon marionetta suspension point

April 27th, 2006 Paola Puppo – INFN Roma ILIAS 1. Silicon mirror 2. Copper reaction mass of the mirror 3. Silicon marionetta with shaped copper insert to optimize the thermal contact with suspensions, and steel arms 4.Reaction mass for marionetta Cryogenic Payload, scaled to 1/3 a Virgo payload 1

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Assembly test: thermal links on aluminum samples of marionetta and mirror

April 27th, 2006 Paola Puppo – INFN Roma ILIAS 1. Mirror assembly 2. Marionetta assembly in its reaction mass 3. Connection of the thermal links 1 2 3

April 27th, 2006 Paola Puppo – INFN Roma ILIAS 4.Mirror reaction mass assembly 5.Coils assembly 4 5

April 27th, 2006 Paola Puppo – INFN Roma ILIAS 6.The minipayload ready to be suspended on the vacuum chamber flange.

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Mirror Reaction Mass Marionetta arms Marionetta Reaction Mass for Marionetta Ansys simulation

April 27th, 2006 Paola Puppo – INFN Roma ILIAS Conclusions Cancellation of the extra-noise vibration associated to the cooling system: vertical noise measured transfer function measured active control performed thermal study performed Minipayload: first assembly test of the payload with aluminum mirror and marionetta. Next step: to insert the assembled system in the VFC cryostat to cool it down and study the mechanical behavior.