The CEDARs (XCED) are a cornerstone of particle identification in the secondary beams of the SPS experimental areas, playing a crucial role in most of the major experiments. Originally designed and built in the 1970s, these detectors have proven their importance over the years. However, recent years have seen a decline in their reliability, prompting the need for a comprehensive overhaul. The NA-CONS project aims to consolidate our technical knowledge of these detectors — from manufacturing to operation — to restore them to their full potential, ensuring they meet modern safety standards and regain their high reliability.

Among the highlights of this consolidation programme were the in-depth analysis and understanding of the CEDAR mechanical systems, optimising the diaphragm alignment for improved precision, creating a previously unavailable spare CEDAR unit, completing the 3D model of the CEDAR system and establishing a new clean area for CEDAR refurbishment in EHN1.

During the YETS 2023/24, the XCED detectors for AMBER underwent full refurbishment. This joint effort by BE-EA, SY-BI, EN-MME, and BE-CEM was both challenging and exciting, as we took the opportunity to dig deeper into the intricate workings of the CEDAR detectors. Despite intensive studies in recent years, there were still critical questions to answer, making this project even more rewarding.

The hands-on work with these detectors allowed us to identify key areas for improvement. With the knowledge gained, we’ve been able to fine-tune the detectors’ performance, pushing them to their limits.

In response to requests from AMBER physicists in April and October 2024, we took the detectors with serial numbers N02 and N20 into the clean room to enhance diaphragm alignment. With new alignment tooling and the expertise of the Metrology team (EN-MME), we successfully optimised the diaphragm precision, measuring and documenting the improvements before and after realignment. Thanks to this work, we have enhanced the overall detector performance.

In July 2024, we resurrected CEDAR N06 from the so-called “CEDAR Cemetery.” No one knew for sure for how long this detector has been unused, and we were uncertain about its overall condition, the detector turned out to be in surprisingly good shape. The diaphragm showed minimal degradation, and the optics were properly aligned. After replacing consumable parts, checking the optics alignment (thanks to BE-CEM), cleaning the interior, installing new motorization, and realigning the diaphragm, XCED N06 was fully refurbished and is now a valuable spare.

In a collaboration between EC and DC sections, we completed the 3D model of the CEDAR detectors. This finalized model includes all the missing parts and updated references, paving the way for future R&D studies and modifications under the NA-CONS project. This 3D model will serve as a key tool in ongoing improvements.

To maintain the CEDAR detectors, particularly the sensitive optics, a dedicated clean room was established in Building 887/R-P89 in 2020. However, our experience in this space highlighted the need for more room, better lighting, improved XCED supports, and streamlined transport procedures.

As a result, we’re preparing a new Clean Area in EHN1 (Building 887/R-C14). This upgraded space will improve cleanliness, safety, and work efficiency, saving time and resources. The new layout, developed through extensive discussions with experts also from other equipment groups, offers greater flexibility, enabling it to serve not only the XCED but also other equipment used in the experimental areas.

With all these experiences, we are ready for the challenge to come.

- Story by Krystian Sidorowski, Miguel Lino Diogo Dos Santos, Vincent Marchand