WP5: High Energy Complex


CEA will provide the overall coordination of the activity and of the communication of its results. It will monitor work progress and inform the project management and work package participants, monitor the WP budget and use of resources and prepare internal and deliverable reports. Other Participants are INFN, CERN, HUD, RHLU, BNL.


WP5 will perform a design of the pulsed synchrotrons of the acceleration complex and will explore an alternative based on fixed-field alternating gradients. Another objective is the design of the collider to get the target luminosity in the interaction region taking into account the limitations due to collective effects, the machine detector interface and the background to experiment. WP5 will optimize the shielding design of the interaction region and magnets to handle the radiation due to muon decay and other beam losses.


Task 5.1
Collider design (CERN)

This task focuses on study of the feasibility and optimization of the muon collider. The main goal is to develop a credible design concept of the muon collider with a cost estimate. It will develop a consistent lattice for a 3 TeV and 10 TeV com collider. Particular challenges are chromatic effects due to the small beta* and large momentum spread and their correction, control of linear and non-linear momentum compaction to keep small bunch length, acceptable beam induced background levels, control of the neutrino radiation issue, beam operation with moving beam lines and, possibly, non-linear effects.

Task 5.2
Pulsed synchrotron and FFA design (CEA)

This task addresses the feasibility and optimization of the muon acceleration complex with upgrade path based on reasonable assumptions on technology development. This task will address two technical solutions: pulsed synchrotrons and FFA. This task will describe the beamline in a parameter table, provide a full set of lattices and have start-2-end tracking to validate luminosity performance, bunch compression and emittance preservation during the acceleration process. CEA will lead this task and perform the design study of the accelerator complex based on pulsed synchrotrons whereas STFC will focus on FFA. CERN will contribute to the longitudinal dynamics studies and bring expertise in synchrotrons.

Task 5.3
Beam dynamics (CERN)

This task focuses on the transverse collective effects all along the muon accelerator chain and in particular, the ones linked to impedances. This task will study impedance effects to check that the very quick acceleration phase is feasible when high-intensity effects taken into account. The detailed proposed work plan is: i) Compute and store the resistive-wall impedance and wakefield. ii) Perform simulations of transverse beam stability assuming with a single bunch and scan the relevant parameters to set limits on the performance reach. iii) Choose the RF cavity impedance models and extend the previous parameters scan. v) Re-do the same analysis with the 2 counter-rotating bunches. vi) Propose possible mitigation measures and study in particular if pulsed synchrotrons need sextupoles.

Task 5.4
MDI design and background to experiment (CERN)

This task will develop a conceptual interaction region design, which integrates a detector shielding together with the detector envelope and the final focus system and incorporates requirements from other activities. It will quantify particle fluxes for different source terms and study the time dependence with respect to the bunch passage: i) muon decay, ii) incoherent electron-positron pair production at the IP, and iii) beam halo losses. This task will optimize the shielding design with respect to different contributions and explore other possible background mitigation techniques on the machine side. It will assess the need of a halo-removal system for background reduction. It will provide estimates of the long-term radiation damage in the detector. CERN will lead this task. INFN and STFC will bring their expertise in machine-detector interface.

Task 5.5
Radiation studies for the accelerators (CERN)

This task will address the simulation and mitigation of radiation-related effects including the neutrino hazard. This task will quantify the heat load distribution and long-term radiation damage in superconducting magnets due to muon decay and beam halo losses. It will develop a shielding design for arc magnets, in order to: i) avoid quenches, ii) sustain the thermal load, and iii) prevent magnet failures. This task will quantify the radiation environment in the tunnel and caverns and assess the need of machine protection systems including a beam extraction system and input for a beam loss monitoring system. This task will assess the effect of the lattice design on the neutrino distribution, and perform optimizations. It will refine the dose kernel for assessing the surface dose arising from neutrino-induced particle showers.