Highly Transparent Aerogel with Refractive Index < 1.01 for High Energy Particle Detection

Technical Report · Sat Nov 30 00:00:00 EST 2019

OSTI ID:1893159

Horn, Tanja

Aerogel of high optical quality is needed for hadron identification in nuclear physics experiments in the momentum range 3 8 GeV/c, where other techniques are not effective. The large-volume aerogel Cherenkov detectors for the Electron-Ion Collider (EIC) and those in three halls at the Jefferson Lab require aerogel material. This project addresses the need for high-quality, hydrophobic aerogels with a refractive index as low as 1.008 to identify particles at higher momenta and for large tile sizes up to 20 x 20 x 3 cm³ while maintaining good optical and hydrophobic properties. The principal objectives of Phase I program were: Produce and characterize small batches (10-20 tiles) of high-quality aerogels with refractive index =<1.01 for the default 10 x 10 x 1 cm³ tile size. The aerogels should be hydrophobic, radiation hard, and exhibit excellent optical properties. Demonstrate the feasibility for scaling up the aerogel size to 20 x 20 x 3 cm3 with refractive index =<1.01 (and up to 1.06) and maintain optical and hydrophobic properties of the aerogels. During Phase I, Scintilex successfully: Fabricated small batches (10-20 tiles) of refractive index <1.01, as low as 1.009, hydrophobic aerogels with excellent optical properties (scattering length >43mm at 400nm wavelength). Demonstrated the scale up of the size of the aerogel tiles to 20 cm x 20 cm (3 cm thick). In addition to the original Phase I objectives developed a novel method to fiber-reinforce aerogel to improve strength and flexibility for handling and use in Aerogel Cherenkov detectors All Phase I objectives were achieved. Fabrication techniques for producing small batches (10-20 tiles) of aerogel with refractive index <1.01 and nominal dimensions 10 x 10 x 1 cm³ were established. The new aerogels are hydrophobic, radiation hard, and exhibit excellent optical properties, as well as up to ~30% higher light yield than currently available aerogels. The feasibility for scaling up the size was demonstrated with the production of 20 x 20 x 3 cm3 tiles. Aerogels with low refractive indices are very fragile. Numerous tiles break during production, e.g. during the loading process into the extractor, and handling of the final tiles and their installation in nuclear physics detector applications is challenging. This can drive up cost and delay schedules. In addition to the original Phase I objectives, a novel method was developed to mechanically reinforce low refractive index aerogels, which could improve their fabrication, handling, and use in Cherenkov detectors. Phase II will establish the new low index aerogels as a whole Cherenkov detector through definite light yield/efficiency measurements in a particle test beam including a suitable light read-out system. The Phase II project also aims to develop larger scale production capability for aerogels of low refractive index and large tile size while maintaining good tile uniformity to meet large-volume particle detector needs. The second track of Phase II is to produce and characterize the highly-promising fiber-reinforced aerogels as Cherenkov detectors to validate the optical properties of these materials necessary for their use as Aerogel Cherenkov detectors. Looking towards Phase III, the market for Cherenkov detectors has been growing over the last years with new aerogel-based detectors built for the 12 GeV Jefferson Lab and being envisioned for new and future facilities like PANDA/FAIR and the EIC. Aerogel is the key for p/π/K Particle Identification (PID) for momenta >3 GeV/c where time-of-flight techniques cannot be used. Aerogels, with low refractive index will thus find immediate use in Cherenkov detectors for nuclear physics experiments. Examples of aerogel Cherenkov detectors are those in Halls A/C and B at the Jefferson Lab 12 GeV, the (s)PHENIX experiment at BNL, and the LHCb experiment at CERN. Looking toward the future, the plans for the EIC detector design include aerogel in a modular and dual-radiator RICH for pion/kaon/proton separation. Aside from applications in basic science, aerogels have multiple commercially attractive properties that make them useful beyond nuclear and high energy experiments. They may be used for highly efficient daylighting and window thermal insulation.

• Research Organization: Scintilex, LLC
• Sponsoring Organization: USDOE Office of Science (SC)
• Contributing Organization: The Catholic University of America and Aspen Aerogels, Inc.
• DOE Contract Number: DE-SC0019536
• OSTI ID: 1893159
• Type / Phase: STTR (Phase I)
• Report Number(s): DOE-Scintilex-19536-1
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS