Draft MDI Action plan Presented by Lau Gatignon 25 September 2009

Role of the MDI The MDI is the part of the CLIC facility (approximately) inside the detector cavern, i.e. the area in which there is a strong coupling of technical subsystems of the machine and of the physics detectors. The lines for the spent beams shall also be considered part of the MDI. Lau Gatignon, MDI - Mandate, members, priorities

MDI Mandate  In general the CLIC Machine Detector Interface (MDI) Working Group shall provide a meeting forum between people working on the CLIC accelerator and people working on the CLIC physics detectors. For this purpose the WG shall have permanent members from both study teams. For certain subjects of more general interest the WG shall propose speakers for CLIC Friday meetings or the LCD meetings.  The MDI working group shall oversee the detailed technical work needed for the conceptual design (CDR) of the MDI until end 2010 and later for the detailed technical design phase (TDR). The MDI WG is responsible for documenting the concept of the accelerator components in the CDR write-up.  Some of the technical work shall be elaborated within the MDI WG, but most results will be obtained in other WGs (beam dynamics WG, LCD, CES WG, Stabilization WG)  The MDI WG reports to the CTC and to LCD. Lau Gatignon, MDI - Mandate, members, priorities

MDI Mandate (2)  Highest priority for the work until end 2010 are those subjects linked to the “CLIC critical feasibility items”, nota bene:  Choice of the magnet technology for the FF magnets  Integration of these magnets into the detectors, and their alignment  Feasibility study of sub-nm active stabilization of these magnets  Luminosity instrumentation  Spent beam disposal  Beam background backsplash from the post-collision collimators and dumps into the detector  Intrapulse-Beam feedback systems in the interface region  The MDI WG shall respond to the cost WG on request. Lau Gatignon, MDI - Mandate, members, priorities4

MDI Mandate (3)  Issues where the beam delivery system (BDS) influences the beam/background conditions for the detector  Issues where the BDS physically impacts on the detector  Beam background and its impact on the forward (det.+accel.) elements, including backsplash of background particles from one hardware element to the surrounding elements  Beam pipe, beam vacuum and vacuum infrastructure in the interface region  Radiation environment and radiation shielding in the interface region  Cryogenic operational safety issues in the interface region  Magnetic environment in the interface region (shielding of FF quadrupole, correction coils, anti(-DID), stray fields from the detector, etc.)  Overall mechanical integration (including the routing of services) in the interface region  Pull-push elements and scenarios (detector-to-detector interface)  Cavern layout and services (handled principally under CES WG) Lau Gatignon, MDI - Mandate, members, priorities5 Examples of further items that will be discussed in the MDI WG:

Recent priority added Study all options for QD0 stabilisation, not only for L*=3.5 m but also for L*=8 m or some suitable intermediate solution. This study shall include all aspects, including luminosity, beam dynamics, integration with detector. In order to meet the deadline for the CDR, a review will be organised by December 2009 or January 2010

Beam Delivery system, backgrounds This concerns the whole sector from the exit of the Linac up to the IP. Only the QD0 quadrupole is physically located in the region covered by the MDI, but the impact on the detectors is very direct, notably via luminosity, backgrounds, stability, bandwidth A final design for 3 TeV is basically available, but this is not the case yet for the 500 GeV option, where there is no final solution for the  IP. Collective effects must be carefully studied. Development of codes. For the MDI this relates to the strength and radius of the QD0 magnet. A critical issue is the tuning of the final focus system as a whole, which is very important for the efficiency as a hole (time needed for tuning the FF system, detuning time, feedback from luminosity,… ). This is a complicated system with moving quads, 6P, etc. Tests at ATF2 Key factors are the direct and indirect backgrounds from the IP (beam-beam) and the halo coming from the Linac and the collimation system. For the halo, HTGEN simulations and first estimates exist, but the must be complemented with BDSIM tracking to the detectors. At this moment concentrating on the 500 GeV option

Final focus magnet (QD0) At the CLIC meeting on Friday 5th of June the permanent magnet based solution was declared the QD0 magnet baseline for the CDR Since then significant activity has started to work towards a magnet design and a fist proposal has been presented at the MDI, ready for comments and input from all parties concerned (stabilisation, vacuum, post-collision line, detector). These will be followed up as far as possible. The required gradient has (almost) been achieved. In parallel contacts are being established with firms to prepare the construction of first prototypes (to measure field strength and quality, vibrations with stabilisation team) and tooling. The idea is to build one PM (“super-strong”) and one hybrid prototype. On the longer term finalisation of the design and construction of a final magnet. Follow up the discussions concerning field tunability requirements, the final L* value (so far 3.5 m as default, but discussions are ongoing) and the dimensioning of the longitudinal layout of the final focus region.

FF Stabilisation Lots of studies have been done for the ILC, to a large extent by the same teams and for the CLIC main linac. But the FF requirements are more stringent: 0.1 nm vertical, 5 nm horizontal, frequencies > 4 Hz For the moment there is no solution yet for the FF stabilisation, but work is progressing, based on passive isolation as well as cantilever based stabilisation. Continue market surveys of seismometers, accelerometers, actuators,…. Lab studies with TMC table. Simulation. Tests in ATF2, CESR? Measurements of motions in typical caverns, in collaboration with other working groups (A.Herve, M.Guinchard, …). Need a magnet at some stage to make further progress: pinpoint vibration sources: measure e.g. with different cooling flows. Stabilisation in push-pull scenario still an open question, but being addressed Design of the final support

Achieved performance CERN TMC active table for isolation  The two first resonances entirely rejected  Achieved integrated rms of 0.13nm at 5Hz LAPP active system for resonance rejection L.Brunetti et al (EPAC/Genova 2008)

Current work Replace big stabilisation table by a compact passive+active stabilisation system Instrumentation study (sensors and actuators) Active system Passive system

Current work Ex : force (actuator) applied to a point Feedback development Simulations Different strategies studied: A knowledge only at strategic points A local model for the disturbances amplified by eigenfrequencies. A complete model Evgeny Solodko FF magnet design

Spent beam line This concerns the design and optimisation of he CLIC post-collision line w.r.t. background conditions for luminosity monitoring equipment and detector and w.r.t. energy deposit in windows, dumps and scrapers. A conceptual design (by A.Ferrari) exists and contains a first set of dipoles, followed by an intermediate dump (to stop wrong sign particles from coherent e + e - pairs – 170 kW) and another group of dipoles to transport the spent beam towards the main dump (10 MW), 150 m from the IP (far away to create space and minimise backsplash). Present activities include background calculations from the spent beam to the detector and onto luminosity detectors, so far only from  ’s on the first dipole, to be extended to the full beam line and also to include neutrons. Refinement of beam transport to increase beam spot. Also thoughts about luminosity monitoring detectors, based on several approaches (e.g.  T in dump, muon pair production from photons on the dump, OTR detectors), in collaboration with the beam instrumentation group (E.Bravin, Th.Lefevre) A dump baseline design exists (ILC) but needs validation for the CDR! Magnet design seems not on the critical path

Magnetic environment A first proposal has been presented at the MDI concerning an anti-solenoid coil concept. A CLIC note is almost completed The stray field of the present FF magnet will be evaluated soon, in particular in the spent beam line The DID dipole must be studied

Vacuum  Confirm the vacuum requirements in he IP and FF regions: Multipacting, bkgd? Assume Torr dynamic pressure for the moment.  Continue discussion of vacuum design in IP region with detector WG  Validate the feasibility of NEG coating in a small radius vacuum tube through QD0 Aim for a lab test before the CDR. Define how to heat the tube (heating wire, heat whole magnet).  Define how to insert the vacuum tube inside the QD0 magnet. Define tolerances. (Or build magnet around the chamber?)  Prepare for CDR, later for TDR

Intra-pulse feedback In order to maintain luminosity with beam sizes at the nanometer scale, an active beam based feedback is required in the Linac and BDS. Intra-train feedback systems at the IP will fight residual jitter and maintain the design luminosity. Note: 0.5 ns bunch spacing, trains of 156 nsec. The FONT group (Feedback On Nano-second Timescales) is studying this. Design of a prototype beam-based intra-train FB system for the IP, for the CDR. Plan to contribute to engineering design. Defining parameters for BPM and kicker, latency and gain. Study and simulate luminosity performance in the presence of dynamic and static imperfections, including interplay of different FB systems. The simulation goals are included in the Low Emittance Transport (LET) studies. Studies also include backgrounds in the interaction region. Simulations based on PLACET, GUINEA-PIG, Octave, in collaboration with CERN Hardware development. Some demonstrations in “warm-RF” based colliders. Working on reduction of the latency time.

Summary of latency times of different FONT tests: Equipment:BPM BPM processor Fast kicker Kicker driver amplifier (Oxford Univ, TMD Technologies company?) DAQ and control/monitoring software

Detector integration and push-pull This concerns the mechanics of the detector, magnetic and radiation shielding, services and the push-pull platform and its movement mechanism. The integration of all the magnets present in the MDI area (detector solenoid & compensation coils, FF quads, anti-solenoid, DID) has to be carefully looked at, their design being a trade-off between detector and machine requirements. Close contact with the CES working group, as the cavern and its infrastructure is determined by the detector layout, e.g. the distance of service caverns from the detectors. Try to take advantage of the presence of both detectors in the same cavern The detector layout and mechanics is being studied in parallel with the evolution of the detector itself, including its mechanical interface to the environment. The push-pull concept is for the moment based on the CMS platform, moved on rollers or air pads and equipped at least with seismic dampers. Either both experiments must be on a platform, or none Detector proximity services have to be thought through in advance, in particularly in a push-pull scenario. In particular liquid Helium, insulating vacuum and power. Stabilisation aspects must be integrated, but there is no solution yet.

Detector moving Air-pads at CMS – move 2000T Concept of the platform, A.Herve, H.Gerwig J.Amann

Civil engineering and services Develop a layout for the interaction region. This includes civil engineering and technical infrastructure. Work with ILC wherever synergies exist. Planning and cost estimates for the construction of the experimental area, including surface buildings. This includes civil engineering, cooling an ventilation, electrical installations, survey, access control, transport and handling, etc. Collaborate closely with the Detector Working Group. Follow up the evolution of the detector and MDI layout, starting from existing preliminary layouts.

Configuration of IR tunnels and halls A. Hervé – H. Gerwig – A. Gaddi / CERN

Cavern layout

Detector working group The Linear Collider Detector project (LCD) is a large international collaboration, in close collaboration with the ILC community. The detector has obviously strong interfaces with the machine, in particular in the experimental cavern (FF magnet, screens, spent beam) but also with the rest of the machine (backgrounds, luminosity) The detector community is represented in the MDI working group and will follow up questions and give feedback whenever required. Close contact via MDI meetings and directly.

Other items Luminosity instrumentation: partly covered by Post-collision line Radiation environment and shielding: need more details on detector Cryogenic safety issues Will need a person to make a reference layout of he MDI region

Membership of MDI WG (1)

Membership of MDI WG (2)

Lau Gatignon, MDI - Mandate, members, priorities37 ORGANISATION: One full meeting every month. If necessary additional meetings in case those are needed to meet specific deadlines. Occasionally restricted meetings could be organised with working group leaders, in particular if these deadlines concern resources. Working meetings on special topics will be organised on a more or less regular basis if so required. E.g. the recent (almost) weekly meetings on the QD0 magnet Stabilisation & integration of QDO