The University of Hawaii Involvement in KamLAND


This is a companion to the main story of the 28 July 2005 publication of the first GeoNeutrino results from KamLAND. We outline the UH involvement in this and similar projects.


The physicists at the University of Hawaii, Manoa Department of Physics and Astronomy, involved in KamLAND are: Dr. Gene Guillian, Prof. John Learned, Ms. Jelena Maricic, Dr. Shigenobu Matsuno, and Prof. Sandip Pakvasa. The Departmental Chair is Prof. Mike Peters, and their Dean is Prof. Chuck Hayes. Prof. Steve Olsen is PI of the DOE High Energy Physics grant at UH, from which this project is supported.

The KamLAND experiment was largely conceived by Prof. Atsuto Suzuki of Tohoku University in Sendai Japan, and he acquired the first and major funding as part of his startup of the Research Center for Neutrino Science (RCNS) at Tohoku, where he had just become Director in 1997. Prof. Suzuki had been consulting with many people in the neutrino research community about such a project, including UH faculty Pakvasa and Learned. UH Prof. Sandip Pakvasa originated the idea for a solar neutrino experiment called Borex, which was proposed for installation in a tunnel (Gran Sasso) in Italy, and Pakvasa was a member of that collaboration. Due to complexities of the distance and other matters, Pakvasa withdrew from that experiment, which evolved into a smaller version called Borexino. That experiment is in fact still under construction, due to operate sometime soon. The rest of the UH faculty team, Learned, and Matsuno are veteran neutrino experimentors and former collaborators of Prof. Suzuki in earlier experiments.

Several people realized that Japan was a nearly ideal location (another would be France) for an experiment to measure electron anti-neutrinos flying from nuclear power reactors spread all around the country. Italy turns out not to be good for this, as there are no nuclear reactors in that country. Borexino is thus aimed at detection of the Be-7 line in the sun. KamLAND will attempt this measurement later (starting in 2006), but it is more difficult as the signature is not so unique and the background problems more severe.

UH has a long history of activity in neutrino research, having been involved in experiments at accelerators and in mines and the ocean for more than 25 years. In particular the UH team played a prominent role in the discovery of neutrinos from Supernova 1987A, which was heralded by many as the discovery of the decade. This observation was carried out with the IMB detector in a salt mine near Cleveland Ohio. UH personnel did the calculations of sensitivity of this experiment in the IMB Proposal, they installed the Bureau of Standard clock which gave the precise time of the explosion (a matter of some contention at that time), and they (along with recent UH graduate Bob Svoboda then at UCI) found the signals and wrote the first reports of the discovery in IMB. This discovery was in parallel with observation of SN1987A neutrino events in the Kamiokande experiment in Japan. This work was highlighted in both the Nobel citations of Prof. Frederick Reines in 1995 and in that of Prof. Masatoshi Koshiba in 2002, both heads of their respective groups, IMB and Kamiokande.

The UH team also played a key role in the analysis and discovery of muon neutrino oscillations, and hence neutrino mass in the Super-Kamiokande detector in 1998. The first significant analyses of these oscillations were carried out at UH, and Dr. John Flannagan wrote the first thesis on muon neutrino oscillations in SuperK, and the initial draft of the SK paper which is now number one cited publication in experimental high energy physics (of all time) was written at UH. While this work was of course a highly collaborative effort with many people and institutions, UH did play a prime role in bringing this work to the fore and to the June 1998 announcement of the discovery now (also) heralded as the most important of the 90's in elementary particle physics (and widely expected to also result in a Nobel Prize within a few years).

UH joined the KamLAND collaboration at the encouragement of Prof. Suzuki, despite the group being heavily committed in SuperK and other activities. We have taken a role in participation in the normal construction and activation activities. Graduate student Jelena Maricic has spent considerable time on-site in construction and calibration work. She has now (as of 6/05) finished her dissertation upon a search for neutrinos from a reactor at the center of the earth. This work is being prepared for publication at this time. Post-Doc Gene Guillian was the project US physicist in residence coordinating Kamioka operations of the experiment. All collaborators take shifts (at least 2 weeks per year) at the mine operating the experiment, which requires tending day and night, every day. We have been actively engaged in the process of writing the KamLAND publications. UH participates in the Collaboration Council and also often hosts the Collaboration Meetings.

UH has undertaken a deisgn study for a project, along with Makai Ocean Engineering, which would be basically KamLAND in the ocean near Hawaii at 4 km depth. The motivation os to make better measurements of the geoneutrinos presently reported upon from KamLand. At the Japanese site 75% of the neutrinos originate in the local crust, and hence the most interesting signal from the mantle and core is hard to detect. In the mid-ocean the situation turns around, and most of the neutrinos arrive from the mantle and core. Moreover, it is very hard to detect any neutrinos from the putative reactor at the center of the earth from a location in Japan which has much of the world's nucelar power plants. The ocean near Hawaii again presents a nearly ideal location. (Everyone asks if nuclear submarines are a problem... they are not, as their reactors are too small).


last updated 7/20/05, jgl.