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| groups:homestake:meetings:20140417 [2014/04/17 11:45] – mandic | groups:homestake:meetings:20140417 [2014/04/17 11:49] (current) – mandic |
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| 3) Analysis of existing data | 3) Analysis of existing data |
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| a) Frames/miniSEED files (Shivaraj, Tanner, Michael) | a) Frames/miniSEED files (Shivaraj, Tanner, Michael) |
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| Shivaraj: almost all frames are copied to the Caltech cluster now, should be done today: | Shivaraj: almost all frames are copied to the Caltech cluster now, should be done today: |
| /archive/frames/MBH | /archive/frames/MBH |
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| b) Estimation algorithms (Shivaraj, Eric, Noah) | b) Estimation algorithms (Shivaraj, Eric, Noah) |
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| Eric: Looking in more detail at the turning depth: http://www.ligo.caltech.edu/~ethrane/stoch/turning_depth2.pdf | Eric: Looking in more detail at the turning depth: http://www.ligo.caltech.edu/~ethrane/stoch/turning_depth2.pdf |
| | Model the rock as 100 thin wafers, with refraction at each boundary. Snell's law applied at each discontinuity, using different wave speeds according to v ~ z^alpha, where alpha=0.27 comes from a different site (expect it to be smaller at Homestake). Find that waves turn around if the incident angle is larger than ~55 degrees (wrt the z-axis). For any alpha, there is a range of input angles that leads to turn over. |
| Model the rock as 100 thin wafers, with refraction at each boundary. Snell's law applied at each discontinuity, using different wave speeds according to v ~ z^alpha, where alpha=0.27 comes from a different site (expect it to be smaller at Homestake). Find that waves turn around if the incident angle is larger than ~55 degrees (wrt the z-axis). For any alpha, there is a range of input angles that leads to turn over. | |
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| Vuk: would like to get better intuition about this - naively, expect small features not to affect much the waves with long wavelengths. In other words, would you expect the turning depth to depend on the frequency/wavelength of the wave? | Vuk: would like to get better intuition about this - naively, expect small features not to affect much the waves with long wavelengths. In other words, would you expect the turning depth to depend on the frequency/wavelength of the wave? |
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| Riccardo/Eric: this is similar to waveguides. The "feature" is small in one dimension, but goes across another dimension, so diffraction intuition is not applicable... | Riccardo/Eric: this is similar to waveguides. The "feature" is small in one dimension, but goes across another dimension, so diffraction intuition is not applicable... |
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| Vuk/Eric: observationaly, from geophysics is it known whether turning depth depends on frequency? | Vuk/Eric: observationaly, from geophysics is it known whether turning depth depends on frequency? |
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| Victor: skin depth (associated with Rayleigh waves) does depend on the frequency (larger for larger wavelength), but not sure how this is related to the refraction argument here. Will try to follow up on it more. | Victor: skin depth (associated with Rayleigh waves) does depend on the frequency (larger for larger wavelength), but not sure how this is related to the refraction argument here. Will try to follow up on it more. |
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| Nelson: may have to go back to the Fermat's principle and solve the problem from scratch. | Nelson: may have to go back to the Fermat's principle and solve the problem from scratch. |
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| Vuk/Eric: it would help to learn what is known about this in geophysics, at least to get a sense of what we need to do. Victor will look into it. | Vuk/Eric: it would help to learn what is known about this in geophysics, at least to get a sense of what we need to do. Victor will look into it. |
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| Vuk: on the other hand, in the radiometer code, this should boil down to changes in phase, which should be calculable for a given model. So we should be able to correct it? | Vuk: on the other hand, in the radiometer code, this should boil down to changes in phase, which should be calculable for a given model. So we should be able to correct it? |
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| Eric: yes, we would have to add angle and depth dependent corrections to the phase. | Eric: yes, we would have to add angle and depth dependent corrections to the phase. |
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| Vuk: will contact Jaret to get more information about the wave speed at Homestake. | |
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| | Vuk: will contact Jaret to get more information about the wave speed at Homestake. |
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