Promising results from HL prototype beam instruments

In the framework of the HL-UK2 collaboration, two novel beam instrument technologies are currently under development. The first is a non-invasive beam imaging system, known as the Beam Gas Curtain (BGC), which observes beam-induced fluorescence produced when charged particles interact with a thin gas jet. The second is a high-bandwidth beam position monitor designed to track intrabeam motion, such as bunch crabbing and transverse bunch instabilities, using innovative Electro-Optical Beam Position Monitor (EOBPM) techniques. Prototypes of these systems have been installed for testing in the accelerator complex during the year-end stops in 2023 and 2024 for the BGC and EOBPM, respectively. A picture of the EOBPM currently installed in the SPS is depicted in figure 1, and of the BGC Monitor in the LHC tunnel in figure 2. A short video showcasing the impressive R&D efforts behind this development can be found here

prototype of EOPPM
Figure 1: Prototype of the Electro-Optical Beam Position Monitor developed in collaboration with Royal Holloway, University of London, installed on the SPS beam line.

Both systems have been commissioned with beams and have already shown promising initial results. Figure 3 shows an image of the beam acquired by the BGC with protons in collision at top energy in the LHC, alongside measurements of intra-bunch transverse oscillations by the EOBPM at injection in the SPS.

team working on beam gas curtain prototype
Figure 2: Prototype of the Beam Gas Curtain Monitor developed in collaboration with the University of Liverpool, installed on the LHC beam line of Point 4.

The prototype instruments will each undergo extensive testing throughout the remainder of the year to fully evaluate their performance. A workshop is planned for the end of the year to compare them with existing systems and technologies in order to converge on the baseline technology choice for transverse beam profile measurements and wideband pickups for the HL-LHC era. Stay tuned!

beam profile alongside graph
Figure 3: First measurements of transverse beam profile with the BGC during LHC run 3 (left) and turn-by-turn intra-bunch transverse oscillations observed with EBPM installed in SPS at injection (right).