After a comprehensive feasibility study, which included extensive theoretical work concerning extraterrestrial neutrino sources, that lasted several years, our small study group composed of a handful of dedicated researchers from the United States, Japan, Germany and Switzerland, including Fred Reines, discoverer of the neutrino and Nobel laureate 1995, established by 1982 the fundamental guidelines for the construction of a giant deep ocean neutrino telescope. The worldwide search for a suitable site revealed that the Kahoolawe Basin, a large flat depression at a depth of nearly 5000 meters in the Pacific, 30 km west of Keahole Point, Hawai'i, satisfied the many requirements necessary for optimum operating conditions. These include a large flat surface at great depth on the ocean floor, clear water, weak currents, low sedimentation rate, close to shore with the necessary infrastructure on shore.

In spring of 1982, we formed the International DUMAND Collaboration with the aim to work out a detailed proposal for the construction of a giant muon and neutrino telescope, to be submitted to our respective national funding agencies. The entire project was subdivided into three stages: construction of a prototype (DUMAND I), construction of an intermediate system (DUMAND II), and extension of the latter or construction of an independent giant telescope with an enclosed volume of about 1 km^3 (DUMAND III or KM3).

As early as 1983 United States and Japanese agencies have made available the funds required for the construction and operation of a prototype detector. This first project stage which consisted of a single string of seven sensor modules with the necessary support systems measured 70 meters in length. It was operated most successfully for several days in November 1987 from a highly stable ship, the Semi Submersible Platform (SSP) Kaimalino, which does not follow the wave motion of the sea (see cover picture). Downward going cosmic ray muon trajectories were recorded at depths ranging from 1500 to 4500 meters. The analysis of the data yielded the angular distribution at different depths and the depth-intensity relation of the muons [1].

(Upward going muons from neutrino reactions could not be expected because of the relatively small size of the prototype telescope and the rareness of these events.)

The experiment delivered unconditional proof that the DUMAND concept, as well as the principles and technologies employed, are fully operational and fulfill the imposed stringent requirements for success.

The following year the same organizations approved the funding profile for DUMAND Stage II. The costs were estimated at U.S. $10 million. This project represented the first genuine neutrino telescope that has a reasonable chance to discover extraterrestrial neutrino sources. It is the inevitable intermediate step toward the giant 1 km^3 detector, needed to carry out a systematic neutrino source survey of the universe [2]. It was only in 1989, after passing many hurdles that funding for the construction of DUMAND II finally was approved by the U.S. Department of Energy, the Swiss National Science Foundation, and funding agencies in Japan and Germany, opening up an entirely new field of science, high energy neutrino astronomy, which harbors an enormous scientific potential. The emphasis is on high energy neutrinos because detection is easier than for low energy neutrinos.

DUMAND II

Figure 1: Sensor matrix of the DUMAND II muon and neutrino telescope. The small circles represent the optical sensor modules (figure not to scale).

Far-reaching technological developments had to be initiated and preceded the prototype as well as the DUMAND Stage II detector, now under construction. Further developments will be needed for the instrument of the next generation (KM3). However, it must be pointed out that to date a remarkable number of new and cutting edge technology products (in acoustics, deep ocean technology, photon detection and electronics) have reached the markets that grew out of the DUMAND project, resulting partly from joint ventures of DUMAND collaborators and various industrial companies from the four collaborating nations. These spin-offs are of value to the economy in general and should not be underestimated.

A study group consisting of members of the now four competing detector systems (DUMAND II, AMANDA, Baikal and Nestor) was formed in November 1994, to carry out a feasibility study for the next generation detector, that will probably be built under the auspices of the OECD, the Organization for Economic and Cultural Development. A letter of intent to unite efforts to build the KM3 detector was signed by representatives of the four collaborations at a conference in Paris in June 1994.