The first LHC crab cavity cryomodule build with the two qualified cavities from CERN is progressing well at Daresbury Laboratory. The DQW cryomodule is the first of four series cryomodules being built by the UK collaboration, following the RFD-SPS delivery, with a fifth DQW cryomodule to be built by CERN.
Since the RFD build, the UK collaboration have taken on additional ISO4 processing on the beam screen bellow assemblies, AKA PIMs (Plug-In-Modules), successfully cleaning and qualifying eight sub-assemblies through an ultra-pure water rinse, an alcohol bath, and clean nitrogen drying before qualification by residual-gas analysis (RGA) and cleanroom particle counts.
The DQW cavity string cleanroom assembly was successfully completed in December 2024, with fundamental power coupler integration completed in February 2025 with support from CERN’s RF group. Since then, the first cryomodule assembly welds have been completed and qualified, as have the secondary beamline connections.
Figure 1. String assembly of the first two DQW series cavities at the UK-STFC facility. Luke Bladen (STFC)
Most equipment for the first UK DQW-LHC cryomodule has now been delivered and accepted by STFC & CERN, aside from the Bi-Phase cryogenic line and 2K multi-layer insulation (MLI) which are in the final stages of fabrication. The successful UK-led manufacturing includes twelve further cryogenic lines, an outer vacuum chamber, warm magnetic shield, 50K thermal screen, 50K MLI, cavity support system and cryogenic instrumentation.
In May 2025, the UK team completed the design and development of cryomodule assembly tooling as well as the production of detailed build procedures – more than 1000 pages! The detailed procedures are a key quality assurance deliverable capturing the micro-steps of each ~11 month build with quality control, sign-off, and many interdependent specialist activities including RF, vacuum, alignment, cleanroom, welding, MLI, and lifting operations.
Figure 2. String assembly of the first DQW series cavities at UK-STFC (left). Vacuum vessel and the cavity string at the cryostating zone at UK-STFC (right). Luke Bladen / STFC
Read other entries related to Crab Cavities:
RF Dipole Cryomodule for SPS Tests (UK & CERN)
DQW Series Production Status - CERN and Research Instruments (RI)