Refining and testing 12,000 km of scintillating plastic fibre for the LHCb SciFi tracker

• Published in: Journal of instrumentation Vol. 13; no. 10; p. P10025
• Main Authors: Cavalcante, A.B.R., Dey, B., Gavardi, L., Gruber, L., Joram, C., Kristic, R., Shinji, O., Zhukov, V.
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 19.10.2018
• Subjects: Aging (natural); Attenuation; Diameters; Large Hadron Collider; Oxidation; Polystyrene fibers; Polystyrene resins; Quality assurance; Radiation tolerance; Scintillating fibers; Shutdowns
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/13/10/P10025

The LHCb Collaboration is constructing a large scintillating fibre tracker for a major upgrade of the experiment during the LHC long shutdown LS2 scheduled for 2019–2020. The detector is based on blue emitting Kuraray SCSF-78MJ fibres of 0.25 mm diameter, read out by linear 128-channel Hamamatsu SiPM arrays. Over a period of about 2 years the full supply of 12,000 km of fibres underwent a systematic and rigorous quality assurance program, including geometrical refinement to deal with rare punctual imperfections. The measurements comprised attenuation length, ionisation light yield, diameter, cladding integrity and radiation tolerance to X-rays. The supply was found to be timely and of very high quality and stability, which led to negligible rejection rates. A small but systematic degradation of the attenuation length by about 1.4% per year is interpreted as natural aging due to oxidation of the polystyrene fibre core and is subject of further investigations.