The TAMA Workshop on Gravitational Wave Detection November 12-15, 1996, Saitama, Japan
Gravitational wave detection specialists from around the world braved the fearsome Tokyo evening rush hour on Monday, November 11, to reach the idyllic National Women's Education Center at Musashi-Ranzan for the first TAMA Workshop. The meeting was planned as a coming out party for TAMA300, Japan's debutante in the present season of large interferometer construction. Although rather petite for its class (the "300" refers to the instrument's 300 meter arms), its many charms were well displayed to those in attendance. And before the meeting had concluded, there was specific discussion of plans for a strapping 3 km sister instrument hoped to follow in a few years.
Talks at the meeting focused on progress around the world in technologies necessary for successful detection of the feeble waves carrying across cosmic distances the messages of the violent deaths of stars or compact binary systems, or perhaps the birth cries of black holes. While proceeding rapidly, interferometer design will have to hurry to keep up with the breakneck pace that the large construction efforts have achieved. Notably, at this meeting the reports from all of the world's approved large projects (LIGO, VIRGO, GEO 600, and TAMA300) included photographs of large quantities of concrete, in some cases still wet but in all cases demonstrating the fruition of plans many years in the making. A glance back at this decades-long history would have been enough to bring tears to one's eyes, were it not for the bracing beauty of the promise of the years ahead.
A sign of the pressing urgency of dreams come true is the attention now being paid to ways to record, store, retrieve, and analyze the mass quantities of data soon to be generated by the world's complement of interferometers. Talks among the various parties, most recently and intensively by LIGO and VIRGO, have led to the outlines of a specification for a common format to be used for recording data; at the TAMA workshop the Japanese scientists signaled their intention to aid in its design. This development was singled out by LIGO P.I. Barry Barish in his toast at the conference banquet, as a mark of the cooperative spirit that has marked this international endeavor and as a crucial step to ensure the linkage of interferometers into a worldwide observatory.
The foreign visitors enjoyed the chance to become better acquainted with the staff of the Japanese collaboration, especially with the students and other young scientist who carry so much of the burden in large projects such as this. A highlight of the meeting was the tour of the site of TAMA300, snugly ensconced underground on the attractive campus of the National Astronomical Observatory at Mitaka, in the Tokyo suburbs. All three buildings and their connecting 300 meter tunnels are complete, and large vacuum hardware is everywhere in evidence. In the vertex building, visitors had the chance to inspect the intriguing X-pendulum low frequency vibration isolation system, under the proud and watchful eye of designer Mark Barton. If the rest of the interferometer can be constructed as nicely as the parts completed to date, then successful attainment of the design sensitivity (rms strain of ) should be possible by the target date of 1999.
Thus, TAMA300 should inaugurate the large interferometer era of gravitational wave detection. If all goes according to plan, it will be joined on the air by GEO 600 (near Hannover) in 2000. VIRGO plans to complete the construction of its 3 km interferometer in Cascina (near Pisa) in 2001. LIGO will have completed construction of its two 4 km long interferometer sites in 1999, followed by a two year period of commissioning. By 2002, its three interferometers (one at Livingston, Louisiana and the 4 km / 2 km pair at Hanford, Washington) are expected to be on the air for an inaugural two year data run. In the meanwhile, the Japanese hope to begin work on a 3 km interferometer by 2000, filling out a network that truly spans the globe.