LIGO diary--report #6

by Wm. Robert Johnston
last updated 1 August 2001

Friday, 20 July 2001: Regarding the RF project: it's over, at least for me. Yesterday the engineers succeeded in setting up a length of welding cable as a ground cable. We were preparing to check the effect on the radio frequency noise and started up the signal analyzer--and the noise was gone (or so it seemed). I spent the morning making readings, then Ken (the electronics engineer) suggested that our loop antenna was broken. He was correct: someone had perhaps stepped on it in the past week.

Once he repaired the antenna (and we saw that the noise was still present), we experimented with using the new grounding cable. Afterwards Ken made some voltage measurements and concluded that there is likely a problem with a particular electronics panel in the LVEA. Unfortunately, this panel is currently being used to pass signals so it cannot be removed and checked. At this point the RF noise project will have to wait until August 6 (after I'm gone), when the panel's designer will be on site.

Another current issue which I might get to dabble in involves the power supply for the facility. Among the many environmental sensors of LIGO is one which monitors the incoming power supplied to the LIGO site by the power company. Since variations in this power (like ones that Brownsville readers will be acutely aware of) can damage equipment and/or produce false information in the detectors, LIGO must monitor it. Yesterday I read a report from the LIGO site in Washington state. By using this monitoring system, they had observed fluctuations in power supply of up to 3%. Additionally, they could see the effect every afternoon when area residents would increase their power consumption for cooking, air conditioning, etc. Next week I may end up involved in looking at results of modifying our site's detector.

Among other things, I have used my leftover time this week to do some reading on suspected black holes. In the past 5 years the number of objects astronomers suspect of being black holes have increased significantly. In addition, some new methods have become involved in identifying possible suspects. Although 29 years have gone by since the first possible black hole was identified, astronomers still can't prove conclusively that any of these objects are black holes. We do have a high degree of confidence for at least a dozen of them. One of the potential results of LIGO is to produce the first definite identification of a black hole.

Antimony gave a presentation today; she is the MIT student that fellow UT-B student Doug has been working with. Her presentation described her study from earlier this summer on variations in the seismic readings in different locations on the foundation of the end station building. An update on the effort to identify the source of the seismic noise: it has been concluded that vehicles on Highway 63 are part of the effect, but probably not the full explanation.

Today I used a digital camera to take some pictures in the LVEA and around the site. I also have pictures from a regular camera. While I have not been successful figuring out how to e-mail any of these via my hotmail account, I will put some on my web site when I return to Brownsville in 8 days.

The weather has remained sunny, with the minor exceptions of a couple of late afternoon rains.

Image credits: Wm. Robert Johnston, © 2001 (all).

© 2001 by Wm. Robert Johnston.
Last modified 1 August 2001.
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