ID :
188684
Wed, 06/15/2011 - 08:59
Auther :
Shortlink :
http://m.oananews.org//node/188684
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Signs of Remaining Type of Neutrino Oscillations Detected in Japan
Tokyo, June 15 (Jiji Press)--An international team of researchers said Wednesday it has become the world's first to detect signs of the type of neutrino oscillations that had remained undetected so far.
The team, including Japan's High Energy Accelerator Research Organization, better known as KEK, unveiled the results of an experiment involving the Japan Proton Accelerator Research Complex (J-PARC) and the Super-Kamiokande elementary particle detector.
"Much remains unknown about neutrinos," Takashi Kobayashi, professor at KEK, said. "The detection marks a step closer to solving the riddle of why the matter in the universe has come to exist."
J-PARC in the eastern Japan village of Tokai produced high-intensity beams of neutrinos and fired them to the Super-Kamiokande underground observatory in the Kamioka mine in central Japan some 295 kilometers away from J-PARC.
In the experiment, widely known as T2K, shorthand for "Tokai to Kamioka," the Super-Kamiokande facility detected neutrinos from J-PARC 88 times between January 2010 and March this year.
Neutrinos, one of the elementary particles that are the basic building blocks of matter, turn from one form into another in neutrino oscillations. The phenomenon has three types and one of the three, whereby muon neutrinos turn into electron neutrinos, had remained undetected.
The Super-Kamiokande facility detected electrons signaling that neutrons went through the undetected type of oscillation during their travel from J-PARC to Super-Kamiokande. Such results were obtained six times during the 15-month period.
These electrons can be detected in other phenomena. But the chance of detecting electrons without neutrino oscillations six times out of the 88 times of neutrino detections is only 0.7 pct, meaning that the probability of the undetected type happening was 99.3 pct, the team said.
Kobayashi said the team needs to raise the probability to at least 99.7 pct in order to convince the particle physics community.
The experiment has been suspended since J-PARC was hit by the March 11 earthquake. The team aims to resume the experiment, only about 2 pct of which has been completed so far, by the end of this year.
The team's finding came after the late Yoji Totsuka in 1998 detected neutrino oscillations for the first time in the world, confirming the presence of a tiny mass of neutrinos.
Totsuka is a student of Masatoshi Koshiba, who won the 2002 Nobel prize in physics by detecting neutrinos from a supernova in 1987 at Kamiokande, the predecessor of Super-Kamiokande.
The team, including Japan's High Energy Accelerator Research Organization, better known as KEK, unveiled the results of an experiment involving the Japan Proton Accelerator Research Complex (J-PARC) and the Super-Kamiokande elementary particle detector.
"Much remains unknown about neutrinos," Takashi Kobayashi, professor at KEK, said. "The detection marks a step closer to solving the riddle of why the matter in the universe has come to exist."
J-PARC in the eastern Japan village of Tokai produced high-intensity beams of neutrinos and fired them to the Super-Kamiokande underground observatory in the Kamioka mine in central Japan some 295 kilometers away from J-PARC.
In the experiment, widely known as T2K, shorthand for "Tokai to Kamioka," the Super-Kamiokande facility detected neutrinos from J-PARC 88 times between January 2010 and March this year.
Neutrinos, one of the elementary particles that are the basic building blocks of matter, turn from one form into another in neutrino oscillations. The phenomenon has three types and one of the three, whereby muon neutrinos turn into electron neutrinos, had remained undetected.
The Super-Kamiokande facility detected electrons signaling that neutrons went through the undetected type of oscillation during their travel from J-PARC to Super-Kamiokande. Such results were obtained six times during the 15-month period.
These electrons can be detected in other phenomena. But the chance of detecting electrons without neutrino oscillations six times out of the 88 times of neutrino detections is only 0.7 pct, meaning that the probability of the undetected type happening was 99.3 pct, the team said.
Kobayashi said the team needs to raise the probability to at least 99.7 pct in order to convince the particle physics community.
The experiment has been suspended since J-PARC was hit by the March 11 earthquake. The team aims to resume the experiment, only about 2 pct of which has been completed so far, by the end of this year.
The team's finding came after the late Yoji Totsuka in 1998 detected neutrino oscillations for the first time in the world, confirming the presence of a tiny mass of neutrinos.
Totsuka is a student of Masatoshi Koshiba, who won the 2002 Nobel prize in physics by detecting neutrinos from a supernova in 1987 at Kamiokande, the predecessor of Super-Kamiokande.
