Radiation damage from energetic particles at GRad-level of SiO ${}_2$ fibers of the Large Hadron Collider ATLAS Zero-Degree Calorimeter (ZDC)

Journal Article · Sun Nov 01 00:00:00 EDT 2020 · Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment

DOI:https://doi.org/10.1016/j.nima.2020.164444· OSTI ID:1640261

Simos, N.; Atoian, G.; Bolotnikov, A.; Sprouster, D.; Tricoli, A.; Medvedev, D.; Palmer, M.; Asner, D.; Charitonidis, N.; Mokhov, N.; Kotsina, Z.

Core SiO₂ quartz fibers of the Large Hadron Collider (LHC) ATLAS Zero-degree Calorimeter (ZDC) are expected to experience integrated doses of a few giga-Rad (Grad) at their closest position to the LHC beam. An array of fibers was irradiated with 200 MeV protons and spallation-generated mixed spectra (primarily fast neutrons) at the Brookhaven National Laboratory (BNL) Linac. Specifically, 1 mm- and 2 mm-diameter quartz (GE 124) rods of 50 mm length were exposed to direct 200 MeV protons leading to peak integrated dose of $~$28 Grad ( $~$0.28 GGy). Exposure of 1 mm-diameter SiO₂ fibers to a neutron flux was also achieved in the spallation field generated by 128 MeV protons. In the post-irradiation analysis, the quartz fiber transmittance was evaluated as a function of the absorbed dose. Significant degradation of the transmittance and increased radiation damage of the material were observed. Microscopic evaluation of the fibers revealed extensive micro-structural damage and irradiation-induced defects. The measurements revealed that a threshold fluence ( $~$2.6 10¹⁶ p/cm²) or dose of $~$10 Grad (0.1 GGy) appears to exist beyond which light transmittance drops below 10%. Also observed is that fiber transmittance loss increased drastically with SiO₂ fiber diameter (1 mm vs. 2 mm diameter). This is attributed, in part, to the earlier lateral leakage from the 1 mm fiber of knock-on electrons and primary protons implying that more damage-inducing protons travel within the bulk of the 50 mm long 2-mm fibers. While Monte Carlo simulations performed tend to support such assumption, future experiments and sensitivity studies are envisioned to address the fiber diameter influence on degradation.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-07CH11359
• OSTI ID: 1640261
• Alternate ID(s): OSTI ID: 1657466
• Report Number(s): FERMILAB-PUB-20-440-AD; S016890022030841X; 164444; PII: S016890022030841X
• Journal Information: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, Journal Name: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment Vol. 980 Journal Issue: C; ISSN 0168-9002
• Publisher: Elsevier
• Country of Publication: Netherlands
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
Quartz fibers
Radiation damage
Energetic protons
Fast neutrons
Transmittance