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diff --git a/physics/LIGO b/physics/LIGO deleted file mode 100644 index ce682b4..0000000 --- a/physics/LIGO +++ /dev/null @@ -1,48 +0,0 @@ -======================================================================= -LIGO: Laser Interferometer Gravitational Observatory -======================================================================= - -.. warning:: This is a rough work in progress!! Likely to be factual errors, poor grammar, etc. - -.. note:: Most of this content is based on a 2002 Caltech course taught by - Kip Thorn [PH237]_ - -Noise Sources -~~~~~~~~~~~~~~~~~~~~~~ - -For initial LIGO, seismic noise dominates below about 60Hz, suspension thermal -noise between 60 and 180Hz, and radiation pressure shot noise above 180Hz. - -Sensitivity -~~~~~~~~~~~~~~~~~~~~~ - -Advanced LIGO will use 40kg sapphire test masses with sensitivity of about 10e-19 meters: 1/10000 of an atomic nucleus, 10e-13 of a wavelength, and half of the entire mirror's wave function. - -LISA -~~~~~~~~~~~~~ - -5e6 km separations between three spacecraft, 1 (astronomical unit, ~1.5e8 from the sun. 1 watt lasers. -The heterodyne detection is of the beat frequencies at each spacecraft of the -two incoming beams. Doppler shifts of spacecraft must be taken into account, -due not only to sun radiation pressure etc, but varying gravitational fields -from planetary orbits. - -The test masses inside LISA should be free falling and have relative -separations stable to 10e-9 cm (10e-5 wavelength of light). - -LISA's sensitivity is in the milihertz regime. - -.. note: (insert LISA noise curve?) - -Data Analysis -~~~~~~~~~~~~~~~~~~~~ - -Using matched filtering (eg, take cross correlation between two waveforms, -integrating their product), frequency sensitivity will be around the inverse -of the number of cycles of waveform (for LIGO, around 20,000 cycles, for LISA -around 200,000 cycles). - -This technique requires known, theoretically derived waveforms (within -phase/amplitude). There are other methods when we don't have good guesses -about the waveform we are looking for... - |