Saturday, October 24, 2009

SciMon Diary: Day 14

Unlike my last post this one's coming to you a bit earlier than normal. That's because when I leave the detector today I will be hitting the road and not coming back. It's my final shift! And afterwards I'm going to be driving up to Vancouver.

As shifts go this one has been very easy. It would have been nice to have an easy shift due to the detector being stable and locked in science mode, but unfortunately this has been easy due to the detector being out of science mode for the whole time! In fact we've been like that for nearly 24 hours (since just after the end of my shift yesterday). It seems that one of the operators (naming no names) yesterday changed some filters that have kind of screwed with our ability to get back into lock - until this morning they weren't even able to initiate the first stage of locking the detector (there are a few stages you go through before you have light locked down both arms at full power). The large earthquake in Indonesia then didn't help things. We* have managed to come back into lock for a while, but with quite a poor range. Hopefully things will improve by the end of my shift, by which time I can hand over the reigns to someone else. [As I type this we've come back into lock!]

*in all these posts when I've said "we" I've generally been talking about something that's been done by the detector operators, whilst I've sat back an watched.

SciMon Diary: Day 13

I'm a day late in posting this, but for completeness feel I should write something. Yesterday's shift involved quite a lot of going in and out of lock. There were a few seismic spikes that may well have been caused by the wind, which had picked up considerably yesterday. This wind made the drive home a bit more fun as I had to battle against it a bit and avoid the tumbleweed flying across the road.

I've not really got anything more to say about the shift, so I'll just add that yesterday evening I watched an episode of Stargate Universe. I've not really watched any of the other Stargate franchise (well I've seen the original film, and caught the odd episode of the original series), but I thought this was very good. From what I've seen I think this is rather darker than the other Stargate spin-offs, and more in the mould of BSG. I don't think there will be many light and fun episodes, with rather more emphasis on lurching from one seemingly hopeless situation to another. Unfortunately I caught episode four (and most of episode five), so I think I'll be having to download the first three (which sort of form a three-part opening episode) when I get home. Robert Carlyle is very good in it too.

Friday, October 23, 2009

SciMon Diary: Day 12

I've not been feeling too well today (I suspect a mild case of radiation poisoning), so I can't really be bothered writing anything. But to satisfy your LIGO cravings here's a LIGO dance:

Note how they form an L-shaped interferometer and the dancers act out the laser light (which is obviously what they intended). They try out a few different, and maybe slightly unconventional configurations though, but I think they throw in a Sagnac there too.

Thursday, October 22, 2009

SciMon Diary: Day 11

Today the student became the master when I got to impart all my SciMon knowledge to a new trainee. Firstly I described the importance of waxing cars, sanding floors, and painting fences, and how they should practice that over and above all else - this bemused the trainee, who thought such things couldn't be applied to looking after a gravitational wave detector. They'll be thanking me when they enter the local SciMon tournament and those SciMons from the other detectors (I'm looking at you Livingston - the evil dojodetector) try dirty tricks to win.

Tuesday, October 20, 2009

SciMon Diary: Day 10

Like last Tuesday (and in fact every Tuesday) today has been a maintenance day at the detector, which means that we've not taken any science mode data and have been out of look for pretty much my entire shift. There's therefore not been much for me to look at detector-wise, so I've been busying myself with me regular work - this has mainly consisted of getting increasingly frustrated with the Frame Library (a set of software that creates, and reads, data in the format that we use for gravitational wave data). I have also attempted to make some inroads into writing my lecture for the SUPA course on gravitational waves (I've not got very far, but if you want a sneak preview of what it'll be like then I'll mainly be talking about stuff from this review article.)

I currently feel like I'm now coming down with a cold, which should make the next few days extra fun!

SciMon Diary: Day 9

Not really much to say today, but I don't want to leave a gap in the diary, so here's my summary of my shift: some science mode; some non-science mode; some seismic noise; no big earthquakes (at least none during my shift - a 6.2 magnitude one in Samoa hit us just after my shift ended.)

To add a bit of spice to this entry I'll let you know what I get up to afterwork! I get home, go the gym, make dinner, watch TV with a couple of beers, go to bed. Sounds exciting doesn't it! I sometimes mix it up with a trip to the supermarket, and today had the great fun of doing some washing. This has been my social life for the last two weeks. I don't know how I'll cope and interact with people when I get back to Glasgow - it'll be sensory overload.

Monday, October 19, 2009

SciMon Diary: Day 8 (week 2)

When I arrived at the detector we'd been in science mode for about 5 hours and that continued for another 7 hours of my shift - a nice 12 hours at a range of ~17 Mpc. I'd been hopeful that we'd stay in lock for the whole of my shift, which would have made things nice and easy, but unfortunately something happened. It did allow me to actually do something in trying to track down the source of the lock loss - it wasn't an obvious seismic event, and various accelerometers on on a variety of optical benches were inconclusive (I had a lot of help to show me what channels I should be looking to perform the diagnostics). By the end of my shift we had some clues, but still didn't know what the ultimate cause was, or whether the same thing had caused loss lock on other occasions. I had learned a fair bit more about the diagnostics software though, and the locations of a variety of optical benches.

Sunday, October 18, 2009

Day off

I started my day with a nice 2 hour 45 minute drive from Richland to the White Salmon river (Google maps was quite accurate in it's allotted trip time). As I said previously I was off to raft the river with these guys. I arrived about an hour early (seeing as I wasn't completely sure how long the drive would take, so I left quite a bit of leeway), so went and had a look at the river and the Husum falls - there were a few kayakers paddling about. I was the first to arrive, but soon after a large group of guys who'd be rafting with us turned up, followed (a bit late) by another local couple. The group were a bunch of guys (mainly from Seattle) who were out on a bachelor weekend - they'd had a big night in Portland the night before, but seemed quite perky and up for it (well the groom-to-be was looking a bit pale, but he made it through ok). Our river guides for the day were Todd (one of the co-founders of the company) and Drew - they kitted us out and then drove us up to the get in.

At the get in (a private get in further up the river than the standard commercial get in, that allowed us to do a load more rapids) we had a introduction to whitewater rafting - how to sit in the boat; how to paddle; what to do if you fall in, etc. We then got split into two groups - it was the bachelor party in one boat with Todd, and the couple (Darrell and Amanda) and me in the other with Drew. Once in the river we did a bit of practicing paddling forward, paddling backwards, and turning, and then got going - the couple had both rafted the river before, so I was the only beginner in the boat. As we had fewer people in our boat we were a bit more nimble and manoeuvrable than the other guys. The top half of the river was a succession of class III rapids and we survived them all and I got the hang a paddling on a raft (which is unsurprisingly quite different that being in a kayak, it being a big open rubbery-ring thing rather than a plastic thing that you're enclosed in). About halfway down we reached a bit where there was a class V fall, which we walked around. After the fall there was the opportunity to rejoin the rafts either by jumping of a ~20 ft drop into the very cold (it being glacial melt water filtered through basalt) water, or walking down. Me and four others choose the jumping option.

After that there were a few more nice rapids, but the main event of the trip was the final Husum falls - about a 10 ft drop that's apparently one of the larger commercially rafted falls in the US. Before reaching it we practiced what to do when we went over the fall - drop onto the floor of the raft and grab onto the available lines. We ran the fall quite easily, but got quite a soaking at the bottom.

Rafting the White Salmon river

It was a fun trip. The guides were really good guys and the other rafters were very nice. But, I have to say, I'd have far preferred to kayak the river. In the raft you actually don't get to do much - you hardly need to paddle - and as it's so big you don't get the proper feeling going through waves and off drops (it kind of smoothes everything out). I do think it would be fantastic to run in a kayak though. I would recommend rafting, but probably you'll enjoy it more if you've not kayaked any class III or higher stuff before. I would also highly recommend doing a trip with Wet Planet Whitewater too.

My drive back was quite tiring and I actually now ache far more from sitting in a car for nearly six hours than from the paddling.

Saturday, October 17, 2009

SciMon Diary: Day 7

So I've reached the halfway point in my scheduled shifts - 7 down and 7 more to go. Today was generally seismically quieter than previous days (maybe the workmen just don't work as hard on a Friday!) and there were no major earthquakes, so we were able to maintain lock for longer and get a better range. We managed to keep in science mode for about half of the shift.

At the start of each shift I have to talk to the outgoing SciMon, look at the electronic logbook (elog) that's kept, and then write an entry detailing the detectors' performance during the shift. We have a variety of figures of merit (FOMs) that are displayed in the control room, examples of which include: a running plot of the range; the detectors state vector (i.e. whether we're in science mode or not); the average power in various frequency bands; the time to which, at the current sensitivity, we could reach the Crab pulsar's spin-down limit; different frequency bands from seismometers located at various parts of the detector (i.e. the central station, or the ends of the two arms of the interferometer); and the glitchiness of the detector. At the end of each shift plots of these FOMs are automatically posted on the elog, and the entry we write basically describes what's shown in the plots, but giving details of things like why we lost lock (which may not be directly obvious from the FOMs), glitches that occurred, and events in the seismic channels. These notes can then either inform the people who work on the detector about potential glitches in the detector system (that they can hopefully fix), or be used if an interesting event is seen in an astrophysical analysis to check that there's no other more mundane reason for the event. Anyway that was a long winded way of me getting round to saying that the automatically generated elog FOM plots were not actually generated before my shift (the script that runs them had accidentally not been restarted following a change), so I had to try and generate my own FOMs to describe what had gone on. I didn't do quite as professional a job with my amateur effort as in the standard plots, but I at least displayed the science segments and range for the previous eight hours.

We again had a school group in the control room today, and again their first questions seemed to be about the two clocks - what is it with school kids and clocks? Have they never seen them before?

My shift ended with us increasing the laser power from the 8W of normal weekday running to the 14W normally used at night and weekends. More power means more sensitivity (see this nice tutorial on laser shot noise for why), but it can also make the detector harder to control and easier to knock out of lock, so that's why the higher power is generally only used when it's seismically quieter. With this higher power we were managing ranges of over 16Mpc. Hopefully that'll continue over the weekend and when I go back in on Sunday we'll have lots of nice data.

Now I just have to prepare myself for tomorrow's rafting trip. Here's a preview of what I'll be doing:

Friday, October 16, 2009

SciMon Diary: Day 6

There was a pleasant surprise this morning when I arrived at the detector. We were in lock, and the nasty noise I mentioned yesterday had gone (although there was still quite a lot of noise making the data below ~100Hz rather jumpy). This noise source caused there to be huge wings/sidebands on the 120Hz and 180Hz lines in the data (these lines are harmonics of the 60Hz line, which comes from the AC frequency of the US mains electricity). The noise seemed to have started when one of the optical benches (on which sits a variety of optics, like mirrors, beam splitters and such) was "landed" - it had previously been floated on a very thin layer of air. So, one of the things that was done yesterday was to re-float the bench. It looks like it was this that improved things, but it's not entirely conclusive (other things like slight realignments were performed). None of that happened during my shift, but it was nice to see the work payoff.

During the shift we were still troubled by the low frequency anthropogenic noise and we only stayed in lock for about half the shift, but that's better than yesterday (when there had been issues other than seismic noise keeping us from reacquiring lock).

We had some excitement in the control room when we were invaded by a large party of local school kids, but the seemed reasonably restrained and asked some questions about the various monitors in the control room (the group was split into two to visit the control room and both groups asked about the two big clocks we have, one of which shows the local time [PDT at the moment] and the other that shows UTC). While they were there I had some pieces of paper, with complicated looking maths on it, so hopefully I looked like a proper scientist to the students.

Thursday, October 15, 2009

SciMon Diary: Day 5

Another poor day for the detector. We weren't having maintenance day today, but we were out of lock for the whole of my shift. It's those pesky workmen again making a lot of noise in the 1-3Hz seismic band. This is the frequency range that relatively local anthropogenic activity generally manifests itself in, so we have a monitor which shows this to check how it correlates with our being in lock, or our inspiral range. Earthquakes generally show up in the 0.03-0.1Hz band and can also knock us out of lock, so we also monitor this (there was a magnitude 6 earthquake today off Samoa, which showed up as a large spike in this band, but as we were out of lock anyway it didn't hurt us).

Seeing as it wasn't looking like we'd get any science data it was decided that we'd let people go and play with the detector in the afternoon. One of the hopes was that we'd be able to track down a source of noise that kept our range down for the last couple of weeks (we should be able to regularly see out to over 16-17 Mpc at night, but we've been maxing out at around 14 Mpc). Hopefully when I go in tomorrow I'll be pleasantly surprised to see that we had an increased range overnight, but it may well be a complicated problem without a quick fix.

Today I also sorted out what I'm going to do on my day off this Saturday - I'll be going white water rafting on the White Salmon river with Wet Planet Whitewater. This should give me my paddling fix and also give me something more exciting to write about on Sunday.

Wednesday, October 14, 2009

SciMon Diary: Day 4

Here's my next eagerly anticipated instalment of exciting tales from the LIGO Hanford Observatory. So what fascinating antics did the detector get up to during my shift today? Well... nothing actually. For all my shift we stayed out of science mode and out of lock due to today being a scheduled maintenance day. During this time there was a big magnitude 6.3 earthquake off Alaska, which most likely would have knocked us out of lock had we been up. Many important things were done to the detector, but it did mean that I wasn't required for much.

One strange thing did happen during the shift though - it rained, and has continued raining for most of the day. It's been completely dry for the previous week, and generally this is a dry place (it is the high desert after all), so it was a nice change to see the familiar weather of back home.

In lunch news it seems that my Philadelphia was as I left it yesterday, and I also discovered a sandwich toaster (which I'd previously though was a George Forman grill), so I was able to have nice toasted bagels.

Tuesday, October 13, 2009

SciMon Diary: Day 3

Today was a rather poor day for the detector. It wasn't behaving very well and refused to stay in lock. To be fair to it it wasn't entirely it's fault - there were some noisy workmen playing nearby (doing something to an irrigation canal apparently) and they kept disturbing it (we think). We only had short segments of good science data and even during those our range was quite low at about 12 Mpc.

A more disturbing occurrence was that I found that some of my Philadelphia, which I have placed in the fridge at the detector, was stolen! I'll see if this flagrant theft continues tomorrow.

Sunday, October 11, 2009

SciMon Diary: Day 2

For my shifts I have to get up at the previously unknown time of 6:40am - it's quite a hardship I can tell you. I bet no-one else has ever had to get out of bed so early to start a job! I then have a 20 min drive along some of the most boringly straight roads you have ever seen (luckily my car has cruise control otherwise I think my legs would just cramp up from the monotony).

At the start of today's shift I was given the folder containing the visitor rules and regulations, which I've had to read. There's a computer use policy in there and I'm not sure if writing this blog constitutes allowed use of the computing infrastructure - it's probably fine.

I learned a bit about how LIGO compensates for the fact that tidal forces stretch the detector arms. We pre-calculate the expected change and perform some thermal adjustments to compensate. However in reality this only corrects for about half the total effect, so we also have to apply some actuation to the end test masses. Our first loss of lock today was caused by one of the controls for these actuators reaching the end of it's allowed range and getting stuck.

I've been trying to teach myself how to use the LIGO DataViewer, which is one of the software tools that allows us to quickly look at the data from all the different channels that the detector produces (it outputs data channels that contain any gravitational wave signal, but it also has hundreds of auxiliary channel monitoring various states of the detector systems). With this I can look at a snapshot of data, have a real time feed, or trend past data, from all the channels available.

I also submitted this paper to The Astrophysical Journal.

In other exciting news today I decided to make my own lunch rather than buy one of the very poor quality sandwiches from the 7-eleven on the way in. I have some bagels and a large tub of Philadelphia, and muffins.

Come back tomorrow to see I can keep up this scintillating, and enthralling, diary.

SciMon Diary: Day 1

Today saw my first day as an expert SciMon - the first of thirteen more days. It being the weekend there weren't really many people at the site, in fact for the most part it was just me and the detector operator (someone who actually knows how to run the detector!). During the shift was based in the control room at the observatory, which looks like this, and has a variety of monitors projected onto the walls - some of the most useful monitors show the current estimated range (the distance, in Megaparsecs, out to which we could observe a binary neutron star coalescence), the sensitivity curve, and a variety of seismometer channels (useful for seeing if there's been an earthquake).

The main (but not only) duty of a SciMon is to document when and why the detector falls out of lock - being in lock means that the interference pattern that the detector uses to sense length changes is held on held just off a dark fringe [I've updated this as I just got reminded that we no longer lock on the dark fringe, but instead use a system where we lock just off the dark fringe (a so-called DC readout) - this is to help us better control the detector] i.e. where the light from the two arms of the interferometer are almost completely cancelling each other out - during this state, and if the detector's behaving itself, it can be said to be in science mode and we can use that data for astrophysical analyses.

For the first half of my shift the detector was behaving itself nicely, and I thought we might make it through the whole 8 hours staying in science mode. But this hope was dashed when a reasonably local earthquake in Nevada knocked us out of lock. The disturbance from this lasted a while, but we got back into science mode and the end of my shift saw us back behaving well. There was also an unexpected interruption in the control room near the end of the run when a tour group came through to observe the detector in operation.

At the end of the shift I handed over to the next SciMon on the 4pm-12am shift, but I'll be back tomorrow. (Posts probably won't get much more exciting than this)

Saturday, October 10, 2009


On Monday I flew out to the US to start my time doing SciMon shifts (as I talked about here) at the LIGO Hanford Observatory (LHO). My first full day here (Tuesday) was not spent at the detector, but was mainly spent in bed overcoming jetlag (and also an illness I seemed to come down with during my flight - not pleasant). But for the last three days I have been out at the detector learning the trade of the SciMon as a trainee. There's been little for me to actually do, but having a computer has meant that I could just get on with my regular work. I have learned what a variety of the monitors that we have in our control room mean (it's a bit like a space mission control room, with banks of screens and computers), and I've seen the effect of the last weeks multiple strong earthquakes on the detector.

Tomorrow I start my first seven days in duty as the "expert" SciMon. After that I then have a day off followed by another seven days of shifts. I'm going to try and write something every day about my experience, so be prepared for 14, probably, fairly dull posts about my experience. I may be going slightly mad towards the end!

Friday, October 09, 2009

Back to the Clyde

In a late post that's just for the record (so I can keep track of what kayaking trips I've been on) I will briefly comment on the bit of paddling I did last Sunday. We had a beginners trip to the Clyde, where, according to this post, I apparently swam last time I did it. I not quite sure how, or where, I swam, because at the section we did it's a very tame river - useful for beginners trips to ease them in to things, but not too exciting for anyone else. I was still grateful to get on the trip as my last river paddling was a while ago and it's all good experience. In fact my general river skills, such as paddling out of eddys properly (eddying out) and paddling across a river (ferrying), aren't too good, so it was nice to practice these - even though I think some of the beginners showed me up a bit on both. The paddle was reasonably uneventful, although there were three swims from two of the new folk (but not me this time!). The beginners seemed to enjoy it and no-one got put off, so hopefully they'll all be back for more. I think I want to get back to rivers with bigger waves and more rapids, just because I don't look as stupid when trying to do simple river manoeuvres - going off weirs and waterfalls I can do!