Andrea Paoli AdV 1 st Project Review Cascina, November 3 rd, 2008 IME – infrastructure modifications for environmental noise reduction

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 2 Virgo experience Environmental noises Seismic, acoustic and magnetic noises contributed to limit the last Virgo sensitivity curve in the 10 to 100 Hz domain. [Reference: Advanced Virgo Preliminary Design, chapter 12, VIR-089A-08, October 2008] Projections of: back-scattered light noise at external benches magnetic noise

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 3 Virgo experience Noises: sources, paths, reduction main noise pathssources And we performed mitigation through reduction of coupling (complementary actions with respect to IME) During Virgo commissioning we identified magnetic noise  reduced mirror magnets strenght seismic/acoustic noise  reduced amount of diffused light on benches  increase stiffness or damping of the benches (under investigation) seismic/acoustic noise  HVAC (Heating Venting Air Conditioning) systems  pumps (water, vacuum)  cooling fans (electronic racks, vacuum) magnetic noise  power supplies  electric motors  electronic racks (suspected)  digital electronics (suspected)  UPS (Uninterrupted Power Supplies) (suspected)  power generators (suspected) seismic/acoustic noise  back-scattered light at optical benches, optical links  input beam jitter  sensing noise of alignment controls magnetic noise  direct coupling to mirror magnets

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 4 noise mitigation: two possible lines of action mitigation of the sources  more silent machines  modification of parts of the machines  proper damping systems  shielding the noisy devices reduction of noise from the sources to the ITF  displacement of the sources far from ITF  improvement of the acoustic isolation  realization of acoustic enclosures  realization of structural joints  damping of the platforms supporting the machines The starting point to define actions and priorities for AdV are the studies and solutions implemented for Virgo commissioning and Virgo+ installation, as well as the study of the environmental noise coupling and the low impact and the low cost solutions foreseen for Virgo+ commissioning. Scope of the IME subsystem

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 5 Noise mitigation Preliminary considerations  modification of parts of the machines (reduction of HVAC fans speed and air flux, balancing of rotating parts, etc.);  seismic isolation of ducts and pipes from the HVAC machine and the walls;  proper damping systems for the machines: springs, elastic pads, separated foundation laid on dissipating layer, etc.;  replacement with more silent machines. Acoustic mitigation is usually harder than seismic isolation. Possible actions are:  keeping potentially noisy sources in separated rooms, acoustically isolated;  isolation of HVAC rooms;  improvement of the air flow distribution: strengthening of plenum, ducts path adjustment, silencers (not effective <100Hz), flow strengtheners, etc.;  relocation of the electronic racks, if feasible; as alternative moving the racks power supplies to dedicated isolated rooms;  improvement of the acoustic reverberation of the experimental halls. Seismic isolation of noisy sources is usually easier than acoustic mitigation. Possible actions are:

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 6 Technical aspects Requirements and specifications for the HVAC machines and electronics racks displacement to be determined soon. Basic requirements:  min distance from the experimental halls;  max level of acoustic noise;  max proper frequency of damping systems. Other issues to be developed soon:  strategy for magnetic noises and relevant involvement on infrastructure modification works;  need to reduce the halls reverberation (this implies considerable works hardly compatible with the halls spaces and the cleaning specifications). However the results expected from V+ can only represent a projection of the present noises on the AdV sensitivity. Given the high impact of the infrastructure modification works and the uncertainties of their results it is necessary to take into account significant safety margins. Interventions “a posteriori” are generally more expensive and difficult to realize.

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 7 As preliminary design, several interventions have been considered for each experimental building and summarized in two solutions: reference solution and further upgrades. Reference solution The infrastructure upgrades to be realized for each experimental building are:  the optimization of the HVAC equipments, through: Status of the design Reference solution /1 -independent platforms supporting the machines; -suspension on adequate anti-vibrating supports; -damping joints for the water pipes; -flexible joints and silencers for the air ducts; -improvement of the air flow distribution (air fans balancing, installation of more noiseless machines, etc.)  the displacement of the electronics racks or their cooling systems in ad hoc spaces (EE Rooms - Electronic Equipment Rooms, acoustic enclosures);  the installation of proper phono-absorbing materials to reduce the high value of the halls’ reverberation time;  no specific works are foreseen to relocate or mitigate the magnetic noise sources.

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 8 IME preliminary design Reference solution /2 HVAC machine dumping system Commercial anti-vibrating support with springs and viscous damper. Horizontal and vertical proper frequency < 2Hz Air ducts Air handler machine Sand layer M0M0 M1M1

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 9 IME preliminary design Reference solution /3 In detail, the works considered for each experimental building are the following: Central Building New external technical area of about 150 m 2 to install the air handler machines. New water pipelines to link the machines to the Technical Building. Separation of the Laser Lab HVAC system from the Clean Rooms one. Realization of an EE Room hosting the electronics racks. Mode Cleaner Building New external technical area of about 25 m 2 to install the chillers (heat pumps) and the air handler machine. Realization of an acoustic enclosure hosting the electronics racks. North & West End Building The air handler machine remain in the current position and the realization of a further structural joint between its foundation and the remaining part of the room has been considered. All the other machines (the heat generator, the air compressor and the electric machines) will remain in their current position, considering that as a sufficient distance. Realization of an acoustic enclosure hosting the electronics racks.

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 10 IME preliminary design Reference solution /4 Central Area Perspective View Central Building Plan View New external technical area 2 Central Building 3 Technical Building 4 EE Room 4 1

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 11 IME preliminary design Reference solution /5 Mode Cleaner Building Perspective View 1 2 Mode Cleaner Building Plan View 1 New external technical area 2 Mode Cleaner Building 3 Acoustic enclosure 1 3

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 12 IME preliminary design Reference solution /6 North End Building Plan View West End Building Plan View 1 Air handler machine Acoustic enclosure

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 13 IME preliminary design Further upgrades A further grade of intervention consists in the realization of new separated technical facilities also for the End Buildings as those considered for the other experimental buildings. These facilities, of about 150 m 2 each, could host the air handler machine and the relevant equipments as well as other potential noisy machines (the heat generator, the air compressor, the electric power generator, the transformer and the UPS machine). End Building Perspective View 1 New external technical building 2 End Building 1 2

AdV 1 st Project Review – Cascina, 03Nov08 - Andrea Paoli IME 14 IME Plan 2009 Preliminary studies, analyses of V+ solutions Definition of requirements PRELIMINARY q1q2q3q4q1q2q3q4q1q2q3q4q1q2q3q4q1q2q3q4q1q4 × AdV Project Review × Detailed design, CsfT, Licensing procedures Realization works