Project
Low-Cost Multilayer Transition-Radiation Targets at the ELSA Test Beam
A winning CERN Beamline for Schools experiment showing household-material radiators produce detectable transition radiation in a GeV electron beam.
Motivation
Transition radiation, the X-rays emitted when a relativistic charged particle crosses a dielectric interface, underlies particle-identification detectors and beam diagnostics across high-energy physics. Conventional radiators use specialized foil stacks and precise geometries that are expensive to produce. Team XTReme’s proposal asked a simple question with practical stakes: can radiator targets built from cheap, ordinary materials produce measurable transition radiation? We submitted the idea to CERN’s Beamline for Schools 2025 competition and were selected as one of five winning teams from 508 proposals across 72 countries.
Methods
I proposed and designed the experiment and engineered its six beamline targets, spanning multilayer polyethylene, aluminized mylar (a consumer space blanket), multilayer Kapton, and single-layer control configurations. The experiment ran in September 2025 at the ELSA electron accelerator at the University of Bonn with beam energies of 1.3 to 3.2 GeV. The detector setup combined a TJ-Monopix2 silicon pixel detector positioned 50 cm downstream of the target, a EUDET-type MIMOSA26 beam telescope, and scintillator triggering through an AIDA-2020 TLU, with data acquisition in Constellation and track reconstruction in Corryvreckan. I participated entirely remotely from Texas, coordinating live accelerator runs with teammates and Bonn physicists on site, and led the analysis of approximately 441 million triggers. Transition-radiation photon candidates were separated from primary electron clusters in two ways: a charge-based analysis exploiting the difference in energy deposition between photons and electrons, and a spatial residual analysis using the angular offset of emitted TR at the downstream sensor plane.
Results
Household materials work. The space-blanket and multilayer-polyethylene targets produced the strongest transition-radiation yields, in agreement with polyethylene-based theory, demonstrating that accessible, low-cost materials can serve as viable radiators for TR-based detector applications. The campaign ran from proposal through target construction, beam time, and analysis as a student-driven experiment.
Dissemination and current status
Results were presented at BTTB14, CERN’s Beam Telescopes and Test Beams workshop. I am first author on a paper accepted for presentation at IEEE RADECS 2026 in Prague (October 28 to November 2), with the expanded manuscript feeding the conference proceedings and a submission to the IEEE Transactions on Nuclear Science special issue in September 2026.
Future work
The near-term work is editorial: the proceedings and TNS uploads, then the Prague presentation. Scientifically, the dataset supports further characterization of yield versus beam energy and layer count, and the low-cost target concept is straightforward for other groups to reproduce.
Materials
- Transition Radiation in Multi-Layered Dielectric–Metallic Targets for Soft X-Ray Generation and Beam Diagnostics | BTTB14PDF
Oral presentation delivered at CERN's 14th Beam Telescopes and Test Beams Workshop in Mainz, covering the design and beam testing of low-cost transition-radiation targets and results from the 441-million-trigger ELSA dataset.