Violin mode amplitude glitch monitor for the presence of excess noise on the monolithic silica suspensions of GEO 600

Abstract

Abstract. Non-Gaussian features of data from gravitational wave detectors are of interest as unpredictable "glitches" limit the sensitivity of searches for many kinds of signal. We consider events due to non-random excitations of the test masses and their suspension fibres. These events could, for example, be related to acoustic emissions in the fibres due to the presence and propagation of cracks or another type of structural perturbation, and they would generate excess noise above the Gaussian background, which matches the level expected due to thermal noise. We look for excess noise in the fundamental violin modes of the monolithic silica suspension fibres of GEO 600. We describe the algorithm used to monitor the violin mode amplitude for glitches, present our results and consider how these may be applied to advanced detectors. The conclusion of our analysis is that no excess noise above what was considered to be thermal noise was observed for several days of h(t) data analysed at the frequency of selected violin modes.PACS numbers: 04.80. Nn, 95.55.Ym, 95.75.Kk, 95.75.Pq

Hydroxide catalysis bonding for astronomical instruments

“…The eight bonded ears have now been in operation for 12 years, a combined duration of 96 years [11] showing no evidence for excess noise arising above what was considered thermal noise from the quasi-monolithic suspension at the violin mode frequency of the suspension fibres in several days of gravitational strain data from the GEO600 detector [67].…”

Invited Article: CO2 laser production of fused silica fibers for use in interferometric gravitational wave detector mirror suspensions

“…Following the success in GEO600, where a total of 20 fibers have suspended the optics for over eight years with no evidence of unexpected problems, 21 planned upgrades to the LIGO and Virgo detectors will include installation of quasimonolithic final stage suspensions. 22,23 Figure 1(b) shows a SOLIDWORKS R (Ref.…”

Creep events and creep noise in gravitational-wave interferometers: Basic formalism and stationary limit

“…I plan to also deal with the issues of non-Gaussianity of the creep-event triggers; it can presumably can be mitigated by considering the output of several independent interferometers. Some comfort for the advanced interferometers can be derived from the fact that experiments [22], [19], and [23] have not observed any influence of the creep noise on the violin-mode motion. We note, however, that all of the measurements in question have searched for the creep noise at high frequencies corresponding to the resonant frequencies of violin modes, from several hundred to several thousand Hz.…”

“…Therefore, currently there is no experimental evidence that the creep excess noise in the future advanced gravitationalwave interferometers will pose a serious problem. However, there are at least two reasons to keep investigating the creep noise: (1) the measurements in [22], [19], and [23] have all been performed at frequencies from several hundreds to thousands of Hz, where the noise of groundbased interferometers is strongly dominated by the quan-tum shot noise, while the danger from creep noise exists at much lower frequencies, in the same region of tens of Hz where the shot noise is unimportant, and (2) the main source of creep noise may well be not inside the fused silica suspension fibers, but inside other carrying parts of the system like the bond between the test masses and the "ears" that are supporting them (Riccardo DeSalvo and Norna Robertson, private communications). It is thus important to understand how a creep event inside the suspension couples to the horizontal motion of the testmass, as well as the frequency dependence of the noise generated by a multitude of the creep events.…”