New Groundbreaking Discovery in Physics


RWTH Aachen provides monitoring chambers for T2K experiment: At the European Physical Society meeting in Stockholm, the international T2K, Tokai to Kamioka, collaboration in Japan announced definitive observation of muon neutrino to electron neutrino transformation.

  Copyright: RWTH Chair of Experimental Physics III B The picture depicts an overhead shot of the detector from the T2K experiment in Japan, which determines the make up of neutrino beams.

"The probability that random statistical fluctuations alone would produce the observed excess of electron eutrinos is less than one in a trillion," says Dr.rer.nat. Stefan Roth from the RWTH Aachen Chair of Experiemental Physics III B. His group provided monitor chambers for detector, which continuously control the gas, with which the T2K track chambers are operated. The monitor chamber system was prepared in Aachen and integrated into the gas system. RWTH Aachen also contributed the chassis for the approximately 1000 ton experimental magnets.

In the T2K experiment in Japan, a muon neutrino beam is produced in the Japan Proton Accelerator
Research Complex, called J-PARC, located in Tokai village, on the East coast of Japan.
The neutrino beam is monitored by a detector complex in Tokai and aimed at the gigantic Super-
Kamiokande underground detector in Kamioka, near the West coast of Japan, 295 km away
from Tokai. An analysis of the data from the Super-Kamiokande detector associated with the neutrino
beam time from J-PARC reveals that there are more electron neutrinos, a total of 28 events, than would
be expected without this new process.

Observation of this new type of neutrino oscillation leads the way to new studies of charge-parity (CP) violation which provides a distinction in physical processes involving matter and antimatter. This phenomenon has only
been observed in quarks, for which Nobel prizes were awarded in 1980 and 2008. "CP violation in
neutrinos in the very early universe may be the reason that the observable universe today is dominated by
matter and no significant antimatter," says Stefan Roth. He adds "This is an important step for solving one of the most profound mysteries in science."

The T2K experiment was constructed and is operated by an international collaboration. The current T2K
collaboration consists of over 400 physicists from 59 institutions in 11 countries, with RWTH Aachen as the only German group involved. The experiment is primarily supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology, MEXT for short, while the RWTH group is funded by the German Research Foundation.

Celina Begolli


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