Takaaki Kajita - 2015 Physics Nobel Laureate

Nobel Week

Nobel Week

December 6-10, 2015 - Nobel Week begins on December 6 with an informal get-together at the Nobel Museum in Stockholm, Sweden. During the week, the Nobel Laureates participate in a variety of activities, including giving a Nobel Lecture at Stockholm University. The highlight of the week is the Nobel Prize Award Ceremony on December 10, and it concludes with individual visits to the Nobel Foundation on December 12. This report includes footage of Prof. Kajita and his guests during the week.

December 4, 2015 − Press Conference at Haneda

During the press conference at Haneda Airport before his departure, Prof. Kajita commented that his guests includes many of his fellow researchers from the Super-Kamiokande collaboration, and that he would like to ''enjoy the coming week together.''

Credit: The University of Tokyo



December 6 − Prof. Kajita donates two types of photomultiplier tubes to the Nobel Museum

Prof. Takaaki Kajita has donated two types of photomultiplier tubes to the Nobel Museum in Stockholm as artifacts related to his research.

A photomultiplier tube is a type of photosensor used in the Super-Kamiokande experiment at the Kamioka Observatory in central Japan. Professor Kajita has donated one sensor each from the Super-Kamiokande inner and outer detectors to the museum.

The Super-Kamiokande detector is filled with 50,000 tons of purified water and is divided into an inner detector, which holds 32,000 tons, and a two meter-wide outer detector that contains the remainder (Figure 1). The wall of the inner detector is lined with around 11,000 photomultiplier tubes, each with a 20 inch (50 cm) diameter (Figure 2), that detect Cherenkov light originating from reactions between neutrinos and water in the inner detector. The 20-inch photomultiplier tube was first developed in 1981 by Hamamatsu Photonics K.K. in collaboration with the University of Tokyo and KEK for the Kamiokande detector. The photomultiplier tubes used in the Super-Kamiokande detector are the result of continuous improvements to this original model. In 2014 the 20-inch photomultiplier tube was recognized with an IEEE milestone award. IEEE Milestones in Electrical Engineering and Computing honor significant technical achievements in electrical, electronics, informatics and communications fields.

Figure 1. The inner and outer detectors of Super-Kamiokande.

Figure 2.A 20-inch photomultiplier tube of the type installed in the Super-Kamiokande inner detector.
(Photo courtesy of Hamamatsu Photonics K.K.)

The outer detector is fitted with 1,885 photomultiplier tubes that are 8 inches (20 cm) in diameter (Figure 3). These photomultiplier tubes detect Cherenkov light originating from cosmic ray muons, a type of elementary particle that is generated by the same cosmic ray interactions that produce neutrinos. Since the outer detector is only two meters thick, each 8-inch photomultiplier tube is attached to an acrylic wavelength shifting plate that is 60 cm square and 1.3 cm thick. This plate transforms the Cherenkov light produced by charged particles into a wavelength that is more easily detected by the photomultiplier tubes, ensuring that each tube is able to capture as much light as possible.

Professor Masatoshi Koshiba, Distinguished Professor of the University of Tokyo and recipient of the 2002 Nobel Prize in Physics, similarly donated a 20-inch photomultiplier tube from the Kamiokande detector to the Nobel Museum in 2002.

Figure 3. An 8-inch photomultiplier tube of the type installed in the Super-Kamiokande outer detector with its wavelength shifting plate.



Exhibitions at the Nobel Museum

The 2015 Physics Nobel exhibition space at the Nobel Museum displays objects donated by both the laureates in one container. Prof. Kajita donated two types of photomultiplier tubes (a 20-inch type and an 8-inch type), and Prof. McDonald donated a bottle of heavy water and a bottle of light water.
The 8-inch photomultiplier tube is currently displayed at the Nobel Museum without the wavelength shifting plate due to limitations of exhibition space.



One of the 2002 Physics Nobel Laureates Prof. Emeritus Masatoshi Koshiba donated to the museum collection a 20-inch photomultiplier tube of the type that was designed for Kamiokande.

During the visit to the museum, 2015 Physics Laureates signed a chair in Bistro Nobel. Prof. Kajita signed his name with the phrase 'Super-Kamiokande Collaboration.'



December 8, 2015 9:00 - 10:20 − Nobel Lecture

At the Aula Magna, Stockholm University, the two 2015 Physics Nobel Laureates delivered lectures on their discoveries that led them to the prize. Prof. Kajita looked back on the path of the neutrino research from the construction of detectors to the discovery of atomospheric neutrino oscillation at Kamiokande and Super-Kamiokande, and forward to the future of neutrino research. Following Prof. Kajita's lecture, Prof. McDonald introduced another story of neutrino oscillation research run parallel to Kamioka's, describing solar neutrino oscillation found at SNO Experiment. Both speakers emphasized the importance of collaborative efforts of the experiments, recognizing many members of their collaboration.

Prof. Kajita delivering his lecture wearing the tie sent to him by the Super-Kamiokande Collaboration.



December 8 12:00 − Reception hosted by the Embassy of Japan

Prof. Kajita and Prof. Omura were invited to the reception hosted by the Embassy of Japan held at the Grand Hotel, where they gave speeches.
Photo: (from left) Ambassador Yamazaki, Prof. Kajita, and Prof. Omura.



December 8 19:00 − Nobel Prize Concert

Prof. Kajita and his guests attended the nobel Prize Concert at the Stockholm Concert Hall.
Photo: Prof. Kajita and his wife, Mrs. Michiko Kajita.



December 9 18:00 − Reception

The Nobel Laureates of 2015, family members and guests were invited to the reception given by the Nobel Foundation and the Royal Swedish Academy of Science at the Nordic Museum.



A photo of Prof. Kajita with the Super-Kamiokande fellow researchers, and the President of the University of Tokyo.



December 10 16:30 - 17:45 −  Nobel Prize Award Ceremony

The Nobel Prize Award Ceremony is about to start.

Nobel Prize Award Ceremony began at 16:30, December 10, at the Stockholm Concert Hall. Prof. Kajita was the first among 2015 laureates to recieved the Nobel Medal and the Nobel Diploma from King Carl XVI Gustaf of Sweden. More than 1500 people attended the ceremony.

©Nobel Media AB 2015/ Pi Frisk

©Nobel Media AB 2015/ Pi Frisk



December 10 19:00 − Nobel Banquet

Nobel Banquet

Following the Award Ceremony, Nobel Banquet was held in the Blue Hall of the City Hall. The Banquet was attended by 1350 guests including the Swedish Royal Family, the 2015 Nobel Laureates and their guests. Mrs Michiko Kajita, escoted by King Carl XVI Gustaf of Sweden, arrived the Hall first among the Nobel Banquet Guests of Honour. Prof. Kajita himself escoted Princess Sofia of Sweden.