From f61026119df4700f69eb73e95620bc5928ca0fcb Mon Sep 17 00:00:00 2001 From: User Date: Tue, 13 Oct 2009 02:52:09 +0000 Subject: Grand rename for gitit transfer --- physics/LIGO.page | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 physics/LIGO.page (limited to 'physics/LIGO.page') diff --git a/physics/LIGO.page b/physics/LIGO.page new file mode 100644 index 0000000..ce682b4 --- /dev/null +++ b/physics/LIGO.page @@ -0,0 +1,48 @@ +======================================================================= +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... + -- cgit v1.2.3