The Future Circular Collider (FCC) Study, hosted by CERN, is an international collaboration of morethan 70 institutes from all over the world. The FCC is a proposed next-generation circular colliderwith a circumference of 100 km and its goal is to push the energy and intensity frontiers of particlecolliders in the search for new physics.

The CERN Survey team is implicated in all stages of the assembly and installation of acceleratorbeamline and experiment detector components for any new project. Our studies are concentratedon those aspects which present new challenges: the need of extensive areas of PermanentMonitoring and Alignment Systems, a potential remote maintenance system, development of newmethods and instrumentation in order to meet the high alignment precision requirements and theextension of the geoid model and reference systems used at CERN.

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eFUTURE CIRCULAR COLLIDER STUDY

N. Ibarrola, M. Jones, D. Missiaen, CERN, Geneva, Switzerland

STUDY OVERVIEW

INTRODUCTION

CONCLUSION AND FUTURE STEPS

GEODETIC WORKS

Physics

Constr. Physics LEP

Construction PhysicsProtoDesign LHC

Construction PhysicsDesign HL-LHC

ConstructionProtoDesignFuture Collider

1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035

20 years

Timelines

Location and Potential Layout

MachinesThree different types of machines are currently under study:

FCC-hh is a 100 TeV proton-proton collider -> Defines infrastructure needs. Alignment precision requirement: ~ 150 μm

FCC-ee is a high-luminosity, high-precision electron-positron collider -> Potential intermediate step.Alignment precision requirement: ~ 17 μm

FCC-eh combines the intense hadron (proton and ion) beams of the LHC and the possible FCC-hhwith the LHeC, a new potential electron accelerator at CERN -> Integration aspects.

Tunnel infrastructure in Geneva areaLinked to CERN accelerators complex

The final FCC layout is yet to be determined and it is continuously changing, trying to find the best agreement between feasibility and cost of the tunnelling works and machine configuration.

12 Points (A-L)• 4 Experimental• 8 Service

Underground Infrastructure

Challenges:• 7.8 km tunnelling through Jura limestone• 300-400 m deep shafts and caverns in molasse

One of the latest potential FCC layouts is the 100 km ‘Intersecting’ option.

ALIGNMENT METHODS

This FCC accelerator complex would be the next large research facility after the High-Luminosity Large Hadron Collider (HL-LHC), when these approach the limits of their discovery potential around 2035.

The FCC project:

Hosted and coordinated by CERNCarried out with partners worldwideLaunched in 2014Conceptual Design Report by the end of 2018

Geoid model- Extension of the CG2000 geoid model within

the FCC study area.- Different geoid model options depending on

the precision requirements: union of different geoid models, additional measurements.

Surface Network

- New pillars along the extended site.- Potential permanent stations near the

main shafts/experiments. - Study of the precision achieved with

different configurations and kind of measurements.

Underground Network- Reference points along the 100 km tunnel – every

50 m (depending on the precision requirements)- Study of the precision achieved with different

configurations and kind of measurements.

16 Caverns• 4 Experimental• 12 Service

16 Shafts• 4 Experimental• 12 Service

Two different infrastructures are under consideration: a single and a twin tunnel design.

Tunnels• 100 km machine tunnel• 2 x ~4 km Injection tunnels• 2 x ~2 km Beam Dump tunnels• Bypass tunnels (RF/transport)• Widened tunnel at FCC-ee IPs

Surface-Tunnel Coordinates Transfer- Currently in the LHC tunnel the depth is up to 100 m. Challenge: The

depth of some main shafts and boreholes would be up to 400 m.- Research on new techniques

Permanent Monitoring and Remote Alignment Systems- Wire Positioning Systems (WPS), Hydrostatic

Levelling Systems (HLS).- Longer distances.- Need to be tested.

Remote Maintenance- Short/long term access restrictions.- Potential need for a remote control and

maintenance system.- i.e. Survey train (under study).

New Alignment Instruments and Methods Improvement of the performance of the alignment instruments. New challenges - Investment in R&D.

ConclusionsStill ongoing work on the reference systems for the FCC site.

What monitoring, alignment and control system technology is required?

Further progress is limited without input on alignment specifications. Could imply R&D.

Next StepsGeodetic reference network simulations.

Validation of instruments in longer distances and refined instrument error models.

Analysis of alignment precisions.

Design control, alignment and monitoring systems.Selected as a function of final alignment precision:

≥ 150 μm, 1 sigma Standard instruments< 150 μm, 1 sigma Options to be studied

Wire Offset Measurements & Levelling- Need to test over longer distances- Study of the airflow, refraction in

the tunnel - Validation of instruments