Charging Issues in LIGO

Abstract:: The Laser Interferometer Gravitational-Wave Observatory (LIGO) consists of Fabry-Perot Michelson interferometers designed to measure gravitational waves at frequencies between 10 Hz and 3 kHz. One potential noise source in this frequency range is the buildup and motion of surface charge on the optics, which can be generated through friction with air, contact with other materials, or interaction with the showers of charged particles generated by cosmic rays. Charge contributes noise by generating fluctuating electric fields, interfering with optical position control, and reducing reflectance by attracting dust to the optical surface. The magnitude of the noise contribution depends both on the amount of charge and the relaxation time associated with its motion; charge densities greater than 105 e/cm2 and relaxation times smaller than 4 × 107 seconds would result in significant noise in the sensitive frequency band. In this talk we will discuss measurements of charge buildup and relaxation times, as well as possible charge mitigation techniques.

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Notes and Changes:: Rev P070068-01-Z:
- Full document number: LIGO-P070068-01-Z
- Author(s): Rupal Amin; Ligo Scientific Collaboration; Gregg Harry; Jim Hough; I. Martin; V. Mitrofanov; S. Reid; Shiela Rowan; Ke-xun Sun; Dennis Ugolini
- Document date: 2007-07-20
- Document received date: 2007-07-20
- Document entry date: 2007-07-20

Rev P070068-00-Z:
- Full document number: LIGO-P070068-00-Z
- Author(s): Rupal Amin; Ligo Scientific Collaboration; E. Elliffe; Gregg Harry; V. Mitrofanov; S. Reid; Shiela Rowan; Ke-xun Sun; Dennis Ugolini
- Document date: 2007-05-29
- Document received date: 2007-05-29
- Document entry date: 2007-05-29

LIGO Document P070068-x0