Advanced LIGO will have more than a factor of 10 greater sensitivity than initial LIGO. Since the volume of space that the instrument can see grows as the cube of the distance, this means that the event rates will be more than 1,000 times greater. Advanced LIGO will equal the 1-yr integrated observation time of initial LIGO in roughly 3 hours.

Advanced LIGO As the initial LIGO interferometers start to put new limits on gravitational wave signals, the LIGO Lab, the LIGO Scientific Collaboration, and international partners are proposing Advanced LIGO to improve the sensitivity by more than a factor of 10. This new detector, to be installed at the LIGO Observatories, will replace the present detector once it has reached its goal of a year of observation, and will transform gravitational wave science into a real observational tool. It is anticipated that this new instrument will see gravitational wave sources possibly as often as daily, with excellent signal strengths, allowing details of the waveforms to be read off and compared with theories of neutron stars, black holes, and other highly relativistic objects. The improvement of sensitivity will allow the one-year planned observation time of initial LIGO to be equaled in just several hours. The change of more than a factor of 10 in sensitivity comes also with a change in the bandwidth of high sensitivity, and the ability to tune the instrument for specific astrophysical sources. This will allow Advanced LIGO to look at the inspiral, coalescence, and ringdown of pairs of black holes up to 50 solar masses, and to pinpoint periodic signals from the many known pulsars which radiate in the range from 500-1000 Hertz. Recent results from the WMAP satellite have shown the rich information that comes from looking at the photon, or infrared cosmic background, which comes from some 400,000 years after the Big Bang. Advanced LIGO can be optimized for the search for the gravitational cosmic background - allowing tests of theories for the development of the universe at only 10-35 seconds after the Big Bang. The LIGO Observatories were planned at the outset to support the continuing development of this new science, and the significant infrastructure of buildings and vacuum systems is left unchanged. The new instruments take advantage of research that has taken place since the initial instruments were designed in the mid-1990’s, and call for changes in the lasers (180 W highly-stabilized systems), optics (40 kg fused silica test masses), seismic isolation systems (using inertial sensing and feedback), and the way in which the microscopic motion (some 10-20 meters) of the test masses is detected. Several of these technologies are significant advances in their fields, and have promise for application in a wide range of precision measurement, state-of-the-art optics, and controls systems. A program of testing and practice installation will allow the new detectors to be brought on-line with a minimum of interruption in observation. The design of the instrument has come from scientists throughout the 40-institution, 400-person LIGO Scientific Collaboration, an international group which carries out both instrument development and scientific data analysis. In the US, these efforts (and in particular the LIGO Laboratory) are supported by the National Science Foundation. In addition, several of our international partners - the United Kingdom-German project GEO600 and the Australian gravitational-wave consortium ACIGA are proposing significant material participation in Advanced LIGO. The materials on this site represent the 2003 proposal to the National Science Foundation. After thorough peer review, Advanced LIGO proposal was approved by the National Science Board in October, 2004, and appears in the President's budget for a recommended start of funding in 2008. We plan to start observations in 2013. The science that follows may well revolutionize our view of the Universe.