10-26-2015, Mainz, Germany
Hunting for Neutrinos with the Help of Specialty Glass from SCHOTT
SCHOTT supplied glass components for the Canadian neutrino telescope, which aided the researchers recently awarded the Nobel Prize in Physics
Elementary particles called neutrinos can actually transform themselves, meaning they have mass. That was the finding of the two scientists, Takaaki Kajita (Japan) and Arthur B. McDonald (Canada), who have been awarded the Nobel Prize for Physics for providing this evidence. The research, done at the Sudbury Neutrino Observatory (SNO) in Canada, proved that neutrinos change their type while they travel from the sun to the Earth. Specialty glass components with superior optical and physicochemical properties, made by SCHOTT, were used in the SNO’s photomultipliers and contributed to the findings.
The heart of the neutrino observatory which is buried two kilometers deep into a nickel mine is the detector with around 10.000 photomultipliers. Photo: SNO
Few particles provide such deep insights into the processes and the history of our universe as the neutrino. Through their experiments, the research teams in Japan and Canada discovered new insights on these elusive particles to “fundamentally change the understanding of matter and the universe,” the jury said.
The standard model of particle physics had always assumed that neutrinos have no mass, but that has been disproved; Kajita and McDonald found that neutrinos, of which there are three types—electron, tau and muon—can switch from one variety to another, and back again. This presupposes a difference in mass, ergo neutrinos have mass.
Precise instruments require high-purity glass components
The SNO is a different kind of telescope. Not only is it the size of a ten-story building, but it’s also buried two kilometers deep in a nickel mine. It’s built underground to filter out cosmic background radiation that could distort the measurements.
Neutrinos are detected in a plastic sphere 12 feet in diameter filled with approximately 1,000 tons of high-purity heavy water. When flying through the water, neutrinos produce very few individual light particles (photons), and require photomultipliers to detect them. These extremely sensitive instruments can detect individual photons by transforming them into electrical signals and amplifying them. The photomultipliers are “the eyes of the detector” and are distributed throughout the entire surface of the water ball. These instruments can not only measure the energy of neutrinos, but also determine their origins.
The photomultipliers are surrounded by a vacuum-sealed glass bulb. The material used in the bulb is a special-purpose glass with unique optical properties that allows ultraviolet radiation from the photons measured to pass through. Scientists from the Canadian Neutrino Observatory turned to SCHOTT to manufacture the glass components during the observatory’s construction in the 1990s.
“The requirements placed on the photomultipliers were extremely demanding. A glass had to be developed specifically for this application and offer excellent optical and physicochemical properties,” recalls SCHOTT materials expert Dr. Werner Kiefer, who was responsible for the SNO Project at the time. SCHOTT’s glass experts used the glass type 8246, which had been advanced specifically to meet these high demands. SCHOTT produced a total of 12,000 individual pieces. “All by hand—and we didn’t receive a single complaint,” Kiefer says.
For SCHOTT, this was a case of successfully participating in a project that will greatly benefit not only scientific knowledge but also everyday applications, SCHOTT Research Fellow Dr. Roland Langfeld says. For example, extremely low-radiation glass is becoming increasingly important as housings for highly sensitive microelectronic components.
Scientists still have many questions about neutrinos, such as where their mass comes from—a mystery that subsequent Nobel laureate generations might be able to solve.
SCHOTT is a leading international technology group in the areas of specialty glass and glass-ceramics. The company has more than 130 years of outstanding development, materials, and technology expertise and offers a broad portfolio of high-quality products and intelligent solutions. SCHOTT is an innovative enabler for many industries, including the home appliance, pharmaceutical, electronics, optics, automotive, and aviation industries. SCHOTT strives to play an important part of everyone’s life and is committed to innovation and sustainable success. The group maintains a global presence with production sites and sales offices in 35 countries. With its workforce of approximately 15,400 employees, sales of $2.55 billion were generated in fiscal year 2013/2014. us.schott.com
Important for the quality of the neutrino measurements are glass bulbs with excellent optical and physical-chemical properties. Photo: SCHOTT
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