Open plasky opened 4 years ago
Nangush
commented
4 years ago Update Figure 2
[ ] Figure 2 needs to be updated to contain the final noise budget.
[x] Clarify figure 2b, or caption as appropriate. It should use the characteristic strain of A+,CE, and ET. Design sensitivity typically refers to strain sensitivity of a detector.
ddobie
commented
4 years ago [x] "Detectors like the Einstein Telescope plan to limit low- and mid-band frequency noise sources such as thermal noise by operating at 20 K, which is not compatible with high circulating power. Proposals for the third-generation Einstein Telescope..." is clunky. Maybe replace the first sentence with "Third generation detectors plan to limit..."
[x] "We choose to operate the interferometer at 150 K rather than the 123 K speci ed for other third-generation silicon designs. This is to allow the high power that will be absorbed to be radiatively dissipated to the 77 K cooled shields that will surround the test masses and not have to resort to conductive cooling that is complicated and can compromise the suspension thermal noise of the detector." -> "We choose to operate the interferometer at 150 K rather than the 123 K specified for other third-generation silicon designs to allow the high power that will be absorbed to be radiatively dissipated to the 77 K cooled shields that will surround the test masses. We therefore will not require conductive cooling which can compromise the suspension thermal noise of the detector."
[x] "Silicon at a temperature in the range of 120 to 150 K has a low thermal expansion coeffcient and a very high thermal conductivity, meaning that thermal distortion of the mirror surfaces is reduced to very low levels." -> "...a very high thermal conductivity, resulting in low thermal distortion of mirror surfaces"
[ ] "Recently-developed techniques will be implemented to mitigate these effects" - these should be named and elaborated on. The rest of the paragraph is phrased in a slightly confusing way
jade-powell
commented
4 years ago [x] Line 137 - Speed meters and Sagnac style needs references.
[x] Table 1 caption needs explanation of acronyms in the table.
[x] Line 277 - Advanced LIGO should be aLIGO.
[x] Line 335 - "aVirgo". This is the first time the Virgo detector is mentioned in the paper. It should be referenced when it first appears and maybe mentioned earlier like in the introduction.
plasky
commented
4 years ago Comments from David McClelland
[x] Need to bring forward reference to Adhikari’s paper now accepted in CQG and update that reference ([40] I think now R.X. Adhikari, et al (115 authors), “A Cryogenic Silicon Interferometer for Gravitational-wave Detection”, Classical and Quantum Gravity, accepted May 7.)., A lot of EMO is based on this paper and we need to make that clear. So in paragraph 5 we need to reference Adhikari first then lead into CE.
[x] Probably should see if there is a better ref for CE than the Reitze arXiv. Will get back to you.
[x] Length justification : I think we say 4km is chosen for compatibility with existing facilities.
[x] At paragraph 3 page 2, we should also point to Figure 2. Is figure 2 actually discussed in the text?
[x] 10 dB of Squeezing at 2 microns: please cite the following papers that establish this as feasible:
G.L. Mansell, et al “Observation of Squeezed Light in the 2 µm Region”, Phys.Rev.Lett.120, 203603 (2018). M.J. Yap, et al , “Squeezed vacuum control at 2µm”, Optics Letters 44, 5386-5389 (2019).
(In fact when any papers talks about 10dB of squeezing for GW detectors, they should cite M.S. Stefszky, et al “Balanced homodyne detection of optical quantum states at audio-band frequencies and below”, Class.Quant. Grav.29, 145015 (14 pages) (2012).
[ ] Why did you take a punt AlGaAs coatings?
[ ] The last sentence in the first full paragraph on page 4 seems out of place.
A-Graham
commented
4 years ago [x] lines 85 and 88: Does "Firstly" and "Secondly" read better as "First" and "Second"?
[x] line 102: is it stronger to replace the word "assume" with "capitalise on the knowledge"?
[x] lines 105 and 111: do you need a comma after "time" and "concern"?
[x] lines 125-127: Is this alluding to the noise being perhaps Poissonian, and thus increasing the number of photons in the laser beam will increase the signal-to-noise ratio? If so, is the wording correct, given that the noise increases as the signal increases, it's just that the noise-to-signal ratio decreases. This isn't my topic; I apologise if I'm asking for clarification on what are no doubt basic principles to the experts. Similarly, lines 130 & 131 are rather jargon-heavy if you're intending to cater to a broad audience, such as members of OzGrav and further afield.
[x] line 134: would it read better as "... (quantum phase noise)-limited..."
[x] line 137-138: any reference for these interferometers?
[x] "the transmission of the input test mass is set to 1.4%" umm, 1.4% of what? I feel like I'm asking stupid questions, but hopefully it helps to identify areas you may like to consider clarifying further.
[ ] Equation 1: Given that T typically denotes temperature, is a different symbol used/available for "power transmissivity"? Also, is "cav" a better subscript than "src". Well, I'm ignorant to what notation may have already been established in the literature, but I'm assuming you have just created this equation because it appears to have no reference associated with it, nor does the sentence on lines 48-51.
[x] line 154: "This configuration, however, comes with..." It may be better with the two commas.
[ ] line 157 and 160: umm... did you mean "silica" or "silicon dioxide"? Oh, I guess not, reading lines 219, 258 and 268. Would it be helpful to use italic text for the term "silicon" in line 157, or is that really not necessary.
[x] Fig.1 SRM? I'm sure you omitted that just to test who reads this article :) Table 1: FP?
[ ] lines 205-208 are a bit convoluted.
[x] line 228: "state" -> "stated"
[x] lines 234-235: for clarity of expression, should you add the following two commas "This is to allow the high power, that will be absorbed, to be radiatively dissipated..." Actually, this whole sentence needs help...
[x] line 257: "thermo-optic" Hyphen?
[x] lines 262-263: "compared with a comparable" ?
[x] line 296: re-word "found in Ref. [39]"
[ ] line 322: "Modeling has shown THAT ..." Reference?
[ ] line 324 & 329 : missing references
[x] lins 364-365: "instability, and its mitigation, it may..." commas have been added here to try and help with the clarity of this sentence, but perhaps this mucks up the sentence...
plasky
commented
4 years ago * [ ] Clarify figure 2b, or caption as appropriate. It should use the _characteristic strain_ of A+,CE, and ET. Design sensitivity typically refers to strain sensitivity of a detector.
@Nangush: can you please clarify what you mean here? The way I understand it, "design sensitivity" refers to the sensitivity of the instrument when it reaches it's final design specifications. You can represent this using the ASD, PSD, noise amplitude, or any other metric that represents a sensitivity curve. In the top panel of figure 2, we use the amplitude spectral density in units of 1/sqrt(Hz), and in the bottom panel we use the dimensionless noise amplitude, which is just \sqrt(f) times the ASD. This is mentioned explicitly in the caption, and I believe the axis labels are also correct. Sorry if I'm missing something, but can you please clarify?
Nangush
commented
4 years ago * [ ] Clarify figure 2b, or caption as appropriate. It should use the _characteristic strain_ of A+,CE, and ET. Design sensitivity typically refers to strain sensitivity of a detector.@Nangush: can you please clarify what you mean here? The way I understand it, "design sensitivity" refers to the sensitivity of the instrument when it reaches it's final design specifications. You can represent this using the ASD, PSD, noise amplitude, or any other metric that represents a sensitivity curve. In the top panel of figure 2, we use the amplitude spectral density in units of 1/sqrt(Hz), and in the bottom panel we use the dimensionless noise amplitude, which is just \sqrt(f) times the ASD. This is mentioned explicitly in the caption, and I believe the axis labels are also correct. Sorry if I'm missing something, but can you please clarify?
@plasky Conventionally GW instrumentalists will refer to the strain sensitivity as the design sensitivity of the detector. Calling the characteristic strain the design sensitivity will be confusing to instrumentalists, and conflict with its conventional usage in the literature. You risk instrumentalists misunderstanding that you are comparing the strain sensitivity of A+, CE, and ET with the characteristic strain of OzHF. I feel like this is important because the paper discusses, and compares proposed detectors.
plasky
commented
4 years ago You risk instrumentalists misunderstanding that you are comparing the strain sensitivity of A+, CE, and ET with the characteristic strain of OzHF.
The bottom panel is not doing what you suggest. It's comparing the noise amplitude (ie characteristic strain) of all four detectors (A+, CE, ET, OzHF). i.e., it's an apples and apples comparison in that plot.
plasky
commented
4 years ago * Probably should see if there is a better ref for CE than the Reitze arXiv. Will get back to you.
Changed to this paper. I think it's the right one to cite, but people should feel free to say otherwise!
PaulEasterMonash
commented
4 years ago Design concept suggestions:
[x] 86: kilometer-scale
[ ] 88-92: Possibly split into two sentences as follows:
Secondly, high circulating laser-power is required to improve the high-frequency sensitivity. This introduces opto-mechanical instabilities whose control strategies can easily increase the noise in the low-frequency band.
[ ] 110: noise-sources
[ ] 121-122: The high-frequency sensitivity of gravitational-wave interferometers is predominantly...
[ ]134: quantum-phase-noise ???
[ ] 144: line numbering missing input test-mass numerical-relativity tools interferometer carrier-frequency
Nangush
commented
4 years ago
Add issues about Section 2 here