ilias gw meeting mallorca - october 23-24, 2005luca taffarello status of the commissioning of the...

ILIAS GW Meeting Mallorca - October 23-24, 2005 Luca Taffarello

Status of the commissioning of the AURIGA detector

Luca Taffarello

(INFN Sezione di Padova)

on behalf of AURIGA Collaboration

http://www.auriga.lnl.infn.it/images/auriga.jpg


Summary of the talk: New detector set-up First Results, calibration and thermal behaviour Investigation of the un-modelled noise peaks

• Up-conversion of low frequency vibrations

Solution of the problem• New mechanical isolation at low frequency

Result achieved: very stable and gaussian behaviour• Duty Cycle 98 % (from 19th May 2005)



new mechanical suspensions: attenuation > 360 dB at 1 kHz FEM modelled

new capacitive transducer: two-modes (1 mechanical+1 electrical) optimized mass

new amplifier: double stage SQUID 200 energy resolution

new data analysis: C++ object oriented code frame data format

Expected target AURIGA II run with 1999-2003 upgrades



II RUN @ T = 4.5K = data = simulation

Best initial result of II run

Noise hunting in cryogenic operation

•Spurious peaks in the sensitive band•High false alarm rate



Non Stationary Performances

F5

F5

F5

F5

F1

F1

F1

F1

It is possible to classify spurious peaks in correlated “Families” (F1..F5..)in time families appear and dissapear

Tim

e (5

hou

rs)

Sensitive frequency band



Measurement of the real part of the impedence seen by the SQUID

No evidence of discharge

HV E bias=7.5 MV/m

‚ ƒ =865.68 Hz

‚ =914.14 Hz

ƒ =955.63 Hz

Calibration: The dissipations of the 3 sensitives modes

Q in operation ~ 400-1000cold-damping

QLV=1.15 106

QHV=1.15 106

QLV=5 106

QHV=0.74 106

QLV=0.45 106

QHV=0.75 106



Calibration: the mechanical transfer function of the antenna

VERY IMPORTANT not evident excitation with mechanical and-or electromagnetic actuators

A

B

C

A

mechanical modes in the transducer charge line

B

Electromechanical modes

C

Mechanical modes of the charge plates



894 Hz Spurious peak in the sensitive band

SQUID output18-22 Hz

Seismometer 8-22 Hz

Accelerometer Inside vacuum chamber8-22 Hz

4 days friday-monday

Low Frequency Motions are Up-Converted!



Evidence of the connection between the external (seismic) activity

and the spurious peaks excitation in the sensitive band

1

DAY

OUTPUT ofSEISMOMETERon top of the cryostat0-22 Hz

sensitive bandwidth

to determine a correlation between the external disturbances and the response in the sensitive bandwidth

Evidence for nolinear behaviour



Run 590 (Time-Frequency) from Sat 11h-13/11/04 to Mon 12h-15/11/04

Clean Raw Data

Noisy Raw Data

Sat

Sun

Mon

Only during the Sunday nigth it is possible to get clean spectraThe duty cycle “gaussian and stationary” very poor 20 %, evidence of effects of Human Activity



Low frequency mechanical excitation and response in the detector bandwidth

2 example also without electrical field

Shaking frequency 18.62 HzEffect: all the multiple

Shaking frequency 16.57 HzEffect: some cluster with more peaks equidistant 16.57/3 Hz

Not possible to reach shaking frequencybelow 10 Hz the seismic noise is too power



Strategy: new mechanical isolation at low frequency

Step 1: Dissipation stacks material: Polyurethane (Sylodamp by Angst

Pfister),high dissipation Q=2roll-off frequency 8-10 Hz

Step 2: Active-air mounts (Vibraplane by Kinetic Systems)

internal damping Q=2 lower natural frequencies 1-2 Hz,automatic leveling/height control

Hardware up-grades integrated during cryogenic operations



Position control feed-backlift used with the liquid heliuminside the dewars

STEP 1: rubber stacks between floor and cryostat supports2 Dec. 2004



800 850 900 950 10001x10-22

1x10-21

1x10-20

1x10-19

AURIGA T=4.5K

Sh

h

0.5 [

Hz-1

/2]

Frequency [Hz]

- noise prediction- mechanical thermal - LC thermal- SQUID back action - SQUID additive

First breakthrough: achieved design sensitivity (Dec 2004)

60% DUTY CYCLE !!!

Go ahead !!



F5 Veto 236.95+/- 0.2 Hz F5 893.63 Hz

F5 Veto



F5Threshold

veto

F5Noise Amplitude @ 236.95+/- 0.2 Hz

F5Veto

ampl

itude



AURIGA Events [no vetoes]

SN

R

Italian Holiday



AURIGA Events AFTER vetoes

SN

R

Is possible to apply the epoch vetoes and the result is a duty cycle 60 %



SNR Distribution AFTER vetoes (Simulation=Red)

SNR

3 eventswith SNR >10during9 days



Second Step: seismic isolation up-gradeexternal suspensions low frequency with vibrational damping

Air springs: effective above 1-2 Hz



Metal-arc welding on cryostat while keeping liquid helium in

“wings” to support Auriga above the center of mass of the cryostat



Step 2: integration of low frequency suspensions (May 19th)

Final configuration Ferroconcrete Pillar



“Before the up-grade”

“After the up-grade”

Last breakthrough:

achieved 98% Duty Cycle (May 2005)



On line effect (May 19th)

suspension activation

1 hour

Sensitive frequency band



Low frequency motion comparison

0 20 40 60 80 1001E-14

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6Bar endface displacement

24/05/05 air suspensions on 17/05/05 air suspensions off

S xx

1/2

m/H

z1/2

Frequency [Hz]



Absolute amplitude 5.7 10-22 / Hz

Current AURIGA Burst Search• Thermal at 4.5 K • 13.6 days,• Epoch vetoes not needed apart from cryogenic maintenance• Duty time 98%• Very stationary• Gaussian noise• Outliers 9 events/day with SNR > 6• Event rate 3700 /day with SNR > 4


ilias gw meeting mallorca - october 23-24, 2005luca taffarello status of the commissioning of the...

Documents

multipleshaking frequency

low frequency step

low frequency result

hz step

hz seismometer

mondaylow frequency

spurious peaks excitation

new mechanical suspensions