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nibotBig day at work tomorrow.
On friday we blew up a photodiode, the very sensitive component of our gravitational wave detector that senses the intensity of the laser light. This particular photodiode is hard to reach and is inside the vacuum enclosure.
Coming from each arm of the LIGO interferometer there's about 200 watts of laser power. While operating, the detector keeps these two beams very close to being perfectly out of phase, so that they cancel out, leaving only ~0.1 W for the photodiodes. But when there's an earthquake or something we lose control of the instrument and the the high power beams "spill" for an instant. We have a system that's supposed to shutter the photodiodes within 2 milliseconds of this happening, but it didn't work this time. So the photodiode got burned.
Fixing this is kind of an Apollo-13 style operation. The folks in Pasadena and Hanford have overnighted us replacement parts (Okay, so I guess it's not like Apollo 13), and even made a video showing how to disassemble a particular component.
We'll fill the vacuum enclosure with clean air and open it up, then dress up in bunny suits and very carefully try to fix it.
If you were a real nerd (a real nerd with too much time on your hands), you'd already know this from reading the elog (username:reader/password:readonly).
In other LIGO news, we just got an email from an editor at Nature saying:
On friday we blew up a photodiode, the very sensitive component of our gravitational wave detector that senses the intensity of the laser light. This particular photodiode is hard to reach and is inside the vacuum enclosure.
Coming from each arm of the LIGO interferometer there's about 200 watts of laser power. While operating, the detector keeps these two beams very close to being perfectly out of phase, so that they cancel out, leaving only ~0.1 W for the photodiodes. But when there's an earthquake or something we lose control of the instrument and the the high power beams "spill" for an instant. We have a system that's supposed to shutter the photodiodes within 2 milliseconds of this happening, but it didn't work this time. So the photodiode got burned.
Fixing this is kind of an Apollo-13 style operation. The folks in Pasadena and Hanford have overnighted us replacement parts (Okay, so I guess it's not like Apollo 13), and even made a video showing how to disassemble a particular component.
We'll fill the vacuum enclosure with clean air and open it up, then dress up in bunny suits and very carefully try to fix it.
If you were a real nerd (a real nerd with too much time on your hands), you'd already know this from reading the elog (username:reader/password:readonly).
In other LIGO news, we just got an email from an editor at Nature saying:
We are delighted to accept your manuscript "An Upper Limit on the Amplitude of Stochastic Gravitational-Wave Background of Cosmological Origin" in Nature. Thank you for choosing to publish your interesting work with us.I'm pretty sure I had almost nothing to do with this, but, still, it has my name on it! Along with the names of ~4×102 other people.
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no subject
Date: 2009-07-01 04:04 am (UTC)I myself have a few photodiodes lying around. I could send you some as backups. I'm sure they'll just plug right in.
no subject
Date: 2009-07-01 04:09 am (UTC)1/ What made you all (LA speak) lose control?
2? How does this impact your schedule with commissioning, science run, etc?
3/ How do you spell commission?
4/ How long will it take to replace the part and then to get it all up and running again?
5/ What else should I be asking?
6/ How is the new table?
no subject
Date: 2009-07-01 04:13 am (UTC)2. There was going to be a delay of a couple weeks anyway; now this is the excuse for that delay.
3. commission
4. If all goes well, we'll have it fixed by tomorrow night and will be back in operation by the weekend. (It takes time to pump the air out again.)
no subject
Date: 2009-07-01 07:17 am (UTC)