Presso la sezione di Roma INFN è attivo da molti anni un gruppo che si dedica allo sviluppo di rivelatori sempre più sensibili di onde gravitazionali (non ancora osservate direttamente) e che oggi fa parte della collaborazione Virgo.
R&D Misura della conducibilità termica (I) e del fattore di qualità meccanico (II) di fibre di zaffiro (Al 2 O 3 ) Proposte @G23 AA 2012 13 Majorana, Puppo, Rapagnani, Ricci G23, Marconi ELiTES: ET LCGT Interferometric Telescopes Exchange of Scientists Work Package 1 and 2: cryogenics and suspensions In construction!!! The future??? KAGRA L 3 km Einstein Telescope TRI 10 km BOTH UNDERGROUND, CRYOGENICS
Cryogenic facilities for mechanical quality factor and thermal conductivity at the INFN Rome laboratory (University of Rome La Sapienza ) Cryogen cryostats (3) Cryogen free cryostats (2), the most used in last years E. Majorana
Due giovani marziani discesi nel G23 presso Ed. Marconi a La Sapienza Hanno portato avanti gl esperimenti, ma c è ancora del lavoro da fare (Q meas)! Allen Scheie, PA, US Dan Chen, Japan Vibration measurement of the KAGRA radiation shield chendan@icrr.u-tokyo.ac.jp 1.Introduction The Large-scale Cryogenic Gravitational Wave Telescope named KAGRA is under construction in the Kamioka mine in Japan. The main interferometer mirrors will be cooled down to 20K in order to decrease the thermal noise. For cooling, each of these mirrors will be surrounded by a double-stage radiation shield to prevent propagation of 300K radiation and will be connected to two cryocoolers through heat links. The shield vibration can couple into the detector signal via the heat links and scattered light. In order to investigate the impact on the KAGRA sensitivity, we measured the radiation shield vibration while operating the cryocoolers. Then we estimated the influence on the sensitivity of KAGRA. Here, we report the measurement result for the KAGRA cryogenic radiation shield vibration and analysis result. 2.Cryogenic payload Cryogenic payload: cooled suspension system and mirror Radiation shield Sapphire fiber Laser Pulse tube 0.9 W at 4K (2nd) 36 W at 50K (1st) Cryo cooler The main sources of the shield vibration: 1. Seismic motion 2. Cryocoolers Vibration[m/rtHz] Dan Chen, K. Yamamoto, Ettore Majorana B, Luca Naticchioni B, T. Suzuki A, N. Kimura A, Andrea Conte B, S. Koike A, T. Kume A, C. Tokoku, Y. Sakakibara, Alexander Khalaidovski, S. Kawamura and KAGRA Collaboration ICRR The University of Tokyo, KEK A, INFN B 80K 8K Baffle Test mass T=20K seiswrion081910hz09.eps 10-6 Coolers OFF 10-7 T=10.1K 10-8 Consistent with RION 10-9 Increase 10-10 Insidethecryostat 10-1 Outsidethecryostat 1 10 10 2.Sapphire fiber at Rome Heat links Cooling bar Cryo cooler 4.Measurement result and analysis Impact of the radiation shield vibration on the interferometer noise: 1.The vibration of the radiation shield may excite an oscillation of the test mass through the heat links. 2.The scattered laser light is partially reflected by the baffle (connected with shield) and might find its way back into the main laser beam, contaminating the output of detector. Measure the vibration of the radiation shield at low temperature, and estimate the influence on the sensitivity of KAGRA. (Measurement @Toshiba Keihin Product Operations, Yokohama-city). Vibration[m/rtHz] 10-1 1 10 10 f [Hz] f [Hz] Coincidence measurement with RION (horizontal) Measurement with coolers ON/OFF (horizontal) Calculate the ratio to estimate the Assume the same peak level at floor level at shieldpeakatkamioka08070203.eps(t=10k) Kamioka. Kamioka as Yokohama 10-7 Vibration[m/rtHz] 10-8 10-9 10-10 10-1 10-5 10-6 10-7 10-8 10-10 10-12 shieldat kamiokapton Kamioka 10-13 1 10 10 f [Hz] ptonof092501.eps PTON PTOF 10-9 There are many peaks originating from the coolers. The estimated vibration of the radiation shield at Kamioka has peaks from cryocoolers. Strain[1/rtHz] 10-14 10-16 10-18 10-20 10-2 10-24 10-26 10-28 10-30 10-32 10-34 3.Measurement in Toshiba We used an accelerometer developed in Rome Univ. for vertical direction and a Michelson interferometer as an accelerometer developed in ICRR for horizontal direction. INFN acc. ICRR acc. We used a commercial accelerometer(rion) to measure the vibration outside the cryostat. We measured the vibration at low temperature with cryocooler ON/OFF. We estimated the influence on the sensitivity of KAGRA using a code made by T. Sekiguchi. The scattered light effect is not considered. KAGRAdesignsensitivity Noisefromradiationshild 1 10 10 f [Hz] Horizontal component Strain[1/rtHz] 10-14 10-16 10-18 10-20 10-2 10-24 10-26 10-28 10-30 Vertical component luca0819strain10hz.eps Inside the shield RION We inputed our estimated vibration to the attachment points between heat links and shield. design Noisefromradiationshild 1 10 10 The noise from the horizontal vibration component is significantly lower than the requirement. But the noise from the vertical component is higher than the design sensitivity around 20Hz. We have to take care of vertical vibration when we design the cryo-payload. Measurement of sapphire Q for KAGRA mirror suspension 1.Purpose We will use sapphire fibers (φ 1.6 mm) to suspend cooled sapphire mirrors(20k). High thermal conductivity lower cooling time High Q value lower thermal noise Requirements Thermal conductivity: 5000 W/m/K Q value: 5x10 6 etc... In Rome we tested two samples with good thermal conductivity. Fiber 1: 5000 W/m/K @20K Fiber 2: 9000 W/m/K @20K Our purpose is measuring the Q value of these fibers @ 20K 3.Measurement setup Heat links (Al 99.999%) Cable of act. Wires (C85) Electrostatic act. Sensor 4.Measurement result Q 10 7 10 6 10 5 Excite fiber modes ImpexMonolithicf1 (94Hz) ImpexMonolithicf21(1260Hz) ImpexMonolithicf2(1268Hz) ImpexMonolithicf31(3712Hz) ImpexMonolithicf32(3741Hz) calc(ted) 94Hz calc(ted) 1268Hz calc(ted) 3741Hz Displacement sensor Requirement (5x10 6 @20K) Q 10 7 10 6 10 5 signal[v] 0.035 0.03 0.025 0.02 0.015 0.01 0. 05 f [Hz] deti101505at16p41kr.eps 0 0 501 0150 2 0250 3 0350 4 0450 ImpexNon-Monolithicf1 (8Hz) ImpexNon-Monolithicf21(120Hz) ImpexNon-Monolithicf31(3515Hz) time[s] Signal fit We calculated Q from the ring dawn signal. calc(ted) 8Hz calc(ted) 124Hz calc(ted) 3515Hz Modal simulation f1 f2 f3 10 4 10 4 Fiber 1 5000 W/m/K @20K Monolithic ET meeting 22nd-23rd Oct. 2013 @ Hannover Fiber 2 9000 W/m/K @20K HEM quality Non-monolithic Thermopolishing Brazed through alumina 0.86x10 6 @20K,94Hz 6.4x10 6 @20K,88Hz 10 3 10 3 0 50 10 150 20 250 30 0 50 10 150 20 250 30 T[K] T[K] Fiber 1 Low Q Fiber 2 High Q We measured Q values of two kinds of sapphire fiber whose thermal conductivity is higher than the requirement value. One of them (fiber 2) has high Q which is higher than requirement value. This means even non-monolithic fiber can have high Q. HEM quality and thermopolishing might improve Q value.
Proposte @G23 AA 2013 14 Progetto R&D per Advanced Virgo/ET test optoelettronico di una scheda per la rivelazione omodina di radiazione laser in un apparato di squeezing Majorana,Puppo, Rapagnani, Ricci G23, Marconi
SISMICO NEWTONIANO TERMICO SOSPENSIONI TERMICO SPECCHI SHOT PRESSIONE RADIAZIONE
RUMORE QUANTISTICO IN UN INTERFEROMETRO MICHELSON INTERFEROMETRO: USA LA LUCE LASER PER MONITORARE LO STATO DI MOTO DEGLI SPECCHI SOSPESI PRINCIPIO DI INDETERMINAZIONE SHOT X2 RUMORE FASE RADIAZIONE FLUTTUAZIONE POSIZIONE SPECCHI RUMORE PRESSIONE RADIAZIONE X1 RUMORE AMPIEZZA RADIAZIONE FLUTTUAZIONE MOMENTO SPECCHI 7
h h SHOT RP ν ( ) ( ν ) = RUMORE QUANTISTICO DELL INTERFEROMETRO = 1 L 1 mν 2 L hλ c 2π P in hp in 2π 3 λc OTTIMIZZAZIONE ALLA FREQUENZA ν RISPETTO ALLA POTENZA 2 2 ν = ν + ν ( ) ( ) ( ) h h h TOT SHOT RP SQL h = h SQL π 2 ml 2 ν 2 Popt = πcmλν 2 8
RIVELAZIONE OMODINA BILANCIAMENTO OTTICO: STESSA POTENZA INCIDENTE SUI DUE FOTODIODI BILANCIAMENTO ELETTRONICO: STESSE PRESTAZIONI DELL ELETTONICA ELETTONICA DEI DUE FOTODIODI STESSE PRESTAZIONI DELL ELETTONICA ELETTONICA DI SOMMA E DIFFERENZA BASSO RUMORE: ALMENO 10 VOLTE SOTTO LO SHOT NOISE DEL LOCAL OSCILLATOR
PROTOTIPO DI OMODINA SOMMA SELF SUBTRACTION 11
TEST DEL PROTOTIPO MISURA DEL RUMORE ALLE USCITE DEI BLOCCHI E DELLE FUNZIONI DI TRASFERIMENTO MISURA DEL RUMORE DEL LOCAL OSCILLATOR CON AUTO OMODINA
PROTOTIPO DI OMODINA COMMON MODE AMPLIFICATORI A TRANSIMPEDENZA 13