Virgo Logbook

Interferometer_sensitivity_studies (General)

fiori, marque, canuel - 16:28 Wednesday 28 July 2010 (27179)

External Detection Bench diffused light Projection, before and after B1s dump

This morning we performed shakings of the EDB to measured the amount of back scattered light. Then the B1s beam dump was put in place, and the measurement was repeated.
Attached plots show
1) injected seismic lines
2) induced noise in B1 before dumping B1s
3) measured gain before damping B1s: G=13 E-20
4) induced noise in B1 AFTER B1s dumper installation
(bench was excited by the same amplitude noise as in 1)
5) measured gain after B1s installation: G=5E-20
Finally
6) projection of EDB noise contribution to present sensitivity.

Conclusions are:
- B1s beam dump reduced diffused light by a factor roughly 2.5
- EDB noise is not limiting at present
- EDB noise seems not below present design.

Images attached to this report

Comments to this report:

fiori - 16:53 Wednesday 28 July 2010 (27180)

a mistype, of couse legend of Fig. 6 shoud read as "hrec of July 28 2010"

Comments to this report:

fiori - 17:09 Wednesday 28 July 2010 (27181)

sorry, indeed the legend of Fig.6 is completely wrong: red line = projected EDB noise BEFORE dumping B1s, blue line = same projection AFTER B1s beam dump, black solid = our sensitivity of this morning, dashed = V+MS design. I will shortly repost this picture also comparing to a better sensitivity reached last night.