Alignment & Vibration Issues for SuperB M. Esposito, S. Tomassini, INFN-LNF SuperB Workshop – SLAC – October 7th, 2009

Outline LNF Alignment Group ( what we have done and what we can do) Requirements and Tolerances for SuperB Alignment Update on Vibration Studies Conclusions

LNF ALIGNMENT GROUP Hall Probe & Rotating Coil Magnetic measurements for component fiducialization Part of the LNF Mechanical Engineering Service 2 expert technicians and 1 engineer under the responsibility of Eng. F. Sgamma Laser Trackers Leica LTD 840 ( ±15µm+6µm/m) Leica LT 500 (±10µm/m) Optical Instruments 2 Leica T3000 theodolites 2 Leica N3 levels

DA  NE Upgrade Upgrade of the layout based on the Crab waist collision scheme with large Piwinsky angle Fast kickers New bellows IR2 parassitic collisions removal And also

Network completely remeasured in 2007 for the upgrade of the accelerator: -10 free standing LT stations -15m max acceptable measuring distance -0.03mm max RMS value of residuals accepted DAFNE -The 2 IRs have been changed and realigned - The alignment of most part of the rest of the 2 rings was checked and modified only if necessary. We have been able to store the beams in the rings without any vertical correction with a max distorsion of the orbit of ±3mm ( → 0.1mm RMS vertical alignment error)

SPARC 6 module undulator SLAC type acc. sections Seeding laser 1.6 cells RF gun

SPARC magnetic measurements using a Hall Probe machine [4] ACCELERATING SECTION SECTION STEERING MAGNETS SEEDING CHAMBER RF DEFLECTOR construction of specifically designed alignment tools fiducialization with a tactile probe 3D measuring machine. FOCUSING SOLENOIDS FIDUCIALIZATION OF COMPONENTS. GUN AND GUN SOLENOID DIPOLES QUADRUPOLES Laser Tracker capabilities and Leica Axyz software [3] versatility were exploited for fiducialization it represents the reference frame for all alignment and surveying operations. REFERENCE NETWORK for target and optical instrument positioning it is the reference frame for all alignment and surveying operations … addition of “secondary” nodes and realization of Laser Tracker measuring campaigns specifically designed and installed for LT measurements PILLAR SOCKETS BRACKET SOCKETS GROUND SOCKETS it was initially designed for the use of optical instruments [2] SECONDARY SOCKETS

SPARX Project of a different scale Same tolerances or even tighter Asked CERN alignment group (J.P. Queznel) for some suggestions based on their experience on accelerators of bigger size

Streched wire as a reference for an LT measured reference network SPARX CERN built instruments to measure offsets from streched wires EARTH CURVATURE EFFECT h≈D 2 /2R

SUPERB Tolerances? network measurement error propagation along the tunnel (how to estimate it and how to keep it low) reusability of component supports, adjustment systems, fiducials and tools Interference of vibration active damping (where and if necessary) with alignment

Vibration survey (what we did) In order to characterize the site, vibration measurements are foreseen: on ground surface underground The surface measurements were made in a single point very near the railway station and Highway by the Pisa INFN VIRGO group (Dr. Braccini and Eng. Gennai). They made a preliminary measurements on June 8 th and the results were shone at the Perugia meeting. U. Rotundo from the LNF was involved too, but his instrumentations didn’t have enough sensitivity to perform this kind of measurement.

Vibration survey cont’ In order to give an answer to the question from the Perugia meeting: “make coherence measurement”, we have bought six accelerometers (Virgo like) (we are waiting for the devices delivery). In the meantime G. Di Pirro is working on the measurement setup timing: the system is based on GPS synchronization. 100μs of synchronization can be easily achieved and this is enough for measurements on 1000Hz frequency span,. The setup will be ready by the end of November, hopefully. We have decided to buy the hardware in order to have an in house working group with the right expertise even in the future.

Synchronization and acquisition system CPU 1.9 GHz, 2 Gbytes RAM, HD 250 Gbytes Operating System Windows XP Software environment Labview NI PXI-6682 GPS, IRIG-B, IEEE 1588 Sync and Time Module with TCXO NI PXI-4462, 24 Bit, kS/s, 4 Inputs, 118 dB Dynamic Range Trimble Thunderbolt E a GPS receiver that provides a 10MHz GPS disciplined clock GPS splitter GPS antenna G. Di Pirro

Synchronization and acquisition system GPS antenna GPS disciplined clock PXI System GPS splitter G. Di Pirro

Synchronization and acquisition system Modular System A single acquisition system More acquisition system G. Di Pirro

Vibration survey (what we are going to do) The preliminary geological survey finished last week. Thanks to Andrea Jeremy we have organized the next campaign of vibration measurements for next week. The plan is: 1. Make measurements in more surface points at LNF site 2. Make coherence measurements on surface 3. Make coherence measurements between surface and underground On October 13 th, Andrea Jeremy will start the next campaign of vibration measurements at LNF

Underground Measurements On September 14 th the first campaign of geological tests started at LNF site: 4 holes of different depth have been bored in the points shown below. Each hole was tubed with a plastic pipe with an inner bore of about 70mm. A second campaign of other four-five holes is foreseen soon These holes will also be used for underground vibration measurements 50m 40m 30m

Underground Measurements We have two types of vibration sensors: - 2 geophones which can measure ground motion from 0.1Hz to 50Hz but with a diameter of 16.8cm (does not fit in the holes). However, we will bring the geophones which can be used to measure ground motion on surface. - 2 accelerometers which can measure ground motion from 1Hz-10Hz (depending on the level of ground motion: Signal to Noise Ratio) up to 100Hz with a diameter of 6.48cm. So this last one can be put in the holes although it is tight (hole diameter: 7.0cm). Our accelerometer supports will be too large to be put in the holes, but we can fix the sensors to a heavy metal cylinder (we have some at LAPP). Cheers, Benoît

Conclusions LNF alignment group has a good expertise on standard alignment procedures. Their expertise and their instrumentation is available for SuperB collaboration Tolerances for the mechanical alignment of the SuperB components have to be established. Solutions on how to obtain them have to be established and optimized Preliminary single-point vibration measurements for the Frascati site have been performed in June Correlation and (hopefully) underground measurements will be performed very soon LNF are creating a group with the right expertise and the appropriate instrumentation to perform vibration measurements in house in the next future