LIGO Experience in Site Selection, Evaluation and Characterization

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1 1 of 21 - Asiri LIGO Experience in Site Selection, Evaluation and Characterization

2 2 of 21 - Asiri Content What is all about It is about LIGO Why should we care? It is an Experience with some similarities How it all happened Process Criteria Evaluation Characterization

3 3 of 21 - Asiri Laser Interferometer Gravitational-Wave Observatory (LIGO) A scientific collaboration of California Institute of Technology Massachusetts Institute of Technology Funded by National Science Foundation

4 8th International Study Group 4 of 21 - Asiri Aerial View of LIGO Hanford site

5 5 of 21 - Asiri Introduction National Science Board (NSB) approved LIGO Proposal in May 1990 NSB approved a LIGO site selection process and criteria in October 1990 Site Solicitation was issued in Nov Eighteen proposals received in March 1991 NSF announced the two location of the LIGO Sites in February of 1992

6 6 of 21 - Asiri Site selection process To placed site solicitation announcement in Commerce Business Daily (90 day response time) To appoint a committee to evaluate all proposed sites for technical suitability according to the Site Selection Criteria Document analysis of each site s performance relative to Site Selection Criteria Submit a written analysis and recommendations for a set of site pairs to NSF for approval Arrange for final transfer of the selected site

7 7 of 21 - Asiri Site Selection Criteria In General: The Chosen site should permit the highest level of research productivity and overall effectiveness, at a reasonable cost of construction and operation, and with a minimal adverse impact on the environment. Proposals should be evaluated against both technical requirements and cost considerations using the following criteria

8 Site Selection Criteria 1. Science Impact a- Local Parameters i. Site topography affecting LIGO facility critical parameters (angle between arms, arm length, slope of arms). ii. Natural and man-made made ground vibration spectra. 2. Existing Support Infrastructure a- Accommodations for resident staff (housing, schools, shopping, etc.) b- Accommodations and access for visiting staff (lodging, transportation, etc.) c- Local technical support (vendors, maintenance, fabrication, etc. ) 8 of 21 - Asiri

9 9 of 21 - Asiri Construction Cost Impact a- Topography b- Soil and subsurface conditions c- Hydrology and drainage d- Climate e- Environmental restrictions f- Accessibility (roads, rail, etc.) g- Site utilities installation (power, water, sewage, etc.) h- Proximity of soil waste and borrow areas i- Local labor costs

10 10 of n21- Asiri Operation Cost Impact a- Cost of power b- Cost of local labor c- Heating and cooling requirements d- Maintenance requirements e- Travel time and costs for visiting staff 5- Site Availability and Acquisition Costs 6- Security of Facility and Access for Visiting Staff

11 11 of 21 - Asiri Risk Factors a- Environmental risks (earthquakes, floods, windstorms_ b- Potential future man-made made noise from development 8- Local Contributions a- Site acquisition b- Construction c- Operations d- Other financial or in-kind contributions

12 12 of 21 - Asiri Site Evaluation Criteria In General:Based on the information provided in the proposals, information subsequently requested from proposers, information gathered in site visits and publicly available reports, rated each individual site against the Site Criteria. Evaluations were made in five distinct Areas: Site availability and acquisition risk Scientific suitability Construction suitability Operations suitability Risks from environmental sources or future development

13 13 of 21 - Asiri Site Evaluation Process: Site availability and acquisition risk Acquisition risk was rated as low, moderate or high, based on degree of uncertainty in whether the proposer or LIGO could acquire land rights to the site in a timely fashion Scientific suitability Scientific suitability was rated Excellent, Good, Satisfactory, or Poor based on assessment of importance of different noise sources The most important noise sources in the assessment were man-made made sources of vibration which could couple to the interferometers either through the ground or air

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15 15 of 21 - Asiri Site Evaluation Process: Construction suitability This effort represented in a few numerical values. Focused on readily quantifiable site-dependent factors; such as topographic variation (earthwork costs), special features as alignment crossings (roads, streams, etc.), site utilities, etc The evaluation of construction suitability was rated excellent, Good, Satisfactory, Poor aimed to significance of: Geological conditions Environmental considerations Flood control Degree of openness or congestion in the site area which constrains facility placement or construction flexibility

16 16 of 21 - Asiri Site Evaluation Process: Operations Suitability Operation suitability was rated excellent, Good, Satisfactory, Poor based on the balance of positive and negative features in the following areas: Supporting technical infrastructure (size of and distance to nearby technical facilities, local university support) Surrounding communities providing accommodations for permanent and visiting staff and availability of local skilled work force Operating costs ( power costs based on usage, effects of climate on power usage and maintenance Accessibility and travel time for visiting staff

17 17 of 21 - Asiri Site Evaluation Process: Risks from environmental sources or future development The risk category was rated as Low, Moderate, or High based on the Site Evaluation Team s assessment of the likelihood of damage to the facility from the enironment and probability of future development of area which might introduce noise and vibration. Three types of environmental dangers were considered: Earthquakes ( had greatest importance due potential catastrophic damage/rupture to vacuum system,and to sensitivity of delicate suspending components Hurricanes Tornadoes

18 18 of 21 - Name The next three slides show: -The LIGO vibration requirement, an excerpt from LIGO Proposal to NSF, Dec. 89 -The LIGO Displacement Power Spectral Density at initiation of Ambient Ground Vibration Measurement, Feb. 92 -The LIGO Displacement Power Spectral Density at initiation of final design, Dec. 95 The critical foundations for the scientific equipment are the Laser Vacuum Equipment Area (LVEA) at the corner station and the similar foundations at the Mid and End Stations

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20 20 of 21 - Name Note: Requirement for 0.1 Hz to 1.0 Hz is added

21 Ground exited vibration due to ambient, facility-transmitted vibration must be <4x LSPSD Vibrations produced by facility equipment: motors, pumps,chillers, etc. must be ; < 2.4 x 10 7 m/sec 2 for 0.1 Hz<f<1 Hz; < 5 x 10 4 m/sec 2 for 1 Hz<f<50 Hz; < 3 x 10 9 m/sec 2 for f >50 Hz at LVEA. n of n - Name