Status of Virgoa short update

Michele Punturo

A bit of History• July 29 – August 13 2005

– C6 run• Duty cycle: Locking 89%, Science Mode 86%

• September 14-19 2005– C7 run

• Duty cycle: Locking 70%, Science Mode 65%

• 19 September 2005– Shutdown of the interferometer and start of the ISYS upgrade

Upgrade motivations 1/2• Large frequency noise in the ITF

– When the power recycling mirror is aligned large fringes are seen

• Cavity effect between the IMC and the PR• Due to the large amount of light scattered in the IMC• The insertion of a Faraday Isolator at the IMC output was

needed to interrupt the light path from the ITF to the IMC• Locking was impossible in this condition

– Temporary solution adopted decreasing by a factor 10 the light injected in the IT

» Increase of shot noise» Increase of electronic noise

Upgrade motivations 2/2•Structures at ~40, ~54, ~80 and 150 Hz

•More evident when the sensitivity improves

•Many of them were due to the modes of the IB

•Visible on the spectrum because of a mismatch between fmod and IMC length•Excited by the control noise

C6

C7(beginning)

UpgradesLa

ser

LB

B2

B2

Q2 1

Q2 2

RFC_DT

IMC

IMC_D1T

Q1

2

Q1 1 B1p

B1p

B5

B1s

BSWI

WE

NI NE

PR

RFCIB

Q8 2

Q8 1

B7

Q8 1

Q8 2

B8WB

NB

L=6m

L=5.

6m

L=6.4m

L=3km

L=3k

m

OM

C

OB

EB

New IB

New PR• Internal modes of the composite PR were affecting the locking of the ITF

PR transfer function

• Standard Virgo size PR mirror installed

Others upgrade• Other changes:

– New Brewster window (IT/PR link)– New auto alignment system for the Input Mode Cleaner– Laser lab work– Update the layout of the benches– New injection tower flange– Cabling and electronic rack displacement– Laser electronic upgrade– Environmental Monitoring– Linear alignment hardware upgrade– New and low noise RF generator– DAQ upgrade– …

Current status• The suspension in tower of the main components has been completed the

18th of November• The ISYS towers have been closed the 19/12/2005 after a long integration

activity (alignment, local control reactivation,…)– Vacuum

• Failure in a picomotor: tower opened again the 3/01/2006• Locking of the IMC on 00 mode the 05/01/2006• 11/01/2006:

– Starting of the IMC autoalignment• Still failures in the picomotors

• Light start to be injected in the ITF

Noise budget in C7