“Detector activities” after the IB upgrade
Michele Punturo
What we must do
• 0 priority:
– commissioning
• 1 priority:
– Items to be implemented
• Acoustic shielding in the laser lab
• Improvement of the cleanliness procedure in the towers
• New coil drivers
• … (MC LC windows?) …
– Items to be investigated:
• MC end mirror
– Better substrate – Heavier payload
• BS mirror
– Larger mirror
» Reduce scattered light
• Eddy current dissipation
• New electronics
• Thermal compensation & Phase camera
Virgo+ Activities
• New high power laser
– N. Mann
• FS monolithic suspension activities
– M.Punturo
Acoustic Shielding in the LL
• Reduce the cross talk between the acoustic channel and the dark fringe
• All the racks with fans displaced during the shutdown
• A coverage of the laser table and of the external injection bench is under design
– Two offers received:
• 30 k€
• 16 k€
– A third company contacted
• Offer in few days
– Implementation:
• End of winter, beginning of spring
• As soon as an executive design will be available it will be shown in a
detector meeting
Cleanliness improvement in the tower
• Wednesday, past week:
• When the NI problem occurred I prepared (16/04/2003) this list of rules:
– Keep the mirror clean
– Remove the dust particles through an ionized air jet after the integration and tuning procedures
– Inject, during the venting only dray air
– Warm up the mirror, to reduce the probability of condensation on it
• Some of them haven’t been respected
– Need to patch the problem now (cleaning intervention) – Need to solve the problem in the future
• Control of the moisture
• Ionized warm air flux (need of infrastructure upgrade, already indicated in
the urgent purchases in the October 2005 Detector Meeting in Naples)
Actuation Noise
G .L os ur do
New coil drivers
LCoil 3mH 1
2 RCoil 10
Ref. Mass Coil
+
- OUT
R2
R R1 R
Coil Driver
DAC 2
RN 500
DAC 1 Transconductance Amplifier
• Full production of new coil drivers in one year
– Prototypes already installed in the end towers (EM
contamination)
– Simplified solution in the input towers (switch+resistor)
– Simplified solution in the BS tower
• New coil drivers have been designed by INFN Pisa + EGO support to solve the actuation noise problem
– Two different sections
• High power section for lock acquisition
• Low noise section for linear regime
– The two sections are driven by two independent DACs
NEW end MC mirror
• The losses in the MC are 846 ppm (F.Bondu) instead of 115 ppm
• Defects and contamination in the curved MC mirror
• This mirror must be replaced
Small or large MC mirror?
• Two new small substrates have been sent to GS Lumonics (Raffaele, could you confirm?)
• The possibility to use a large substrate must be investigated
– Better control of the payload – “almost” standard geometry – Herasil substrate available
– Movement mechanics complicated
– Optics + Mechanics studies must be started now
New BS?
• Stray light is evident in the BS
IB
WA NI
wedge
• With the higher injected power the problem should be enhanced
– Larger BS needed
Eddy current FUTURE problem
• Virgo design
– M=0.017 A m
2– Stainless Steel RM
•
RM=1.4×10
6W
-1m
-1– Q
eddy=1.8×10
8• Current design
– M=0.05 A m
2– Aluminum RM
•
RM=3.2×10
7W
-1m
-1– Q
eddy=9.4×10
5Experimental test: (VIR-NOT-PER-1390-27 (1996), VIR-NOT-PER-1390-80 (1997), Rev.Sci.Instr. 69, 2777 (1998))
1 1 0 1 0 0 1 0 0 0
1 0 - 2 3 1 0 - 2 2 1 0 - 2 1 1 0 - 2 0 1 0 - 1 9 1 0 - 1 8
h(f) [1/sqrt(Hz)]
F r e q u e n c y [ H z ]
( a ) N o m i n a l V i r g o
( b ) C u r r e n t m a g n e t s M = 0 . 0 5 , A l R M ( c ) N o m i n a l m a g n e t s M = 0 . 0 1 7 , A l R M ( d ) M a g n e t s M = 0 . 0 0 5 , A l R M
Magnetic Field Now
mirror post magnet
Macor support
coil
steel supportA lu m in um R M
With Iron Hat
Test in Clean Room
0 1 2 3
0.2 0.4 0.6 0.8 1.0
B/ B
0layers of 0.6mm Bmeas Model
Model (top larger)
