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Fermilab | Batavia, IL | USA

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In science you never know what will happen

Science is full of surprises such as this laboratory flooding at Yale. Credit: Caitlin Casey

Hi everyone, it’s been a few weeks since I did my introductory post  on who I am (my name is Hugh) and what I’m working on (dark matter detection with bubble chambers, as part of the COUPP collaboration). I fear it has been too long for there to be any continuity between the previous post and this one, so I figured I’d go in a different direction and talk a bit about the uncertainty (or unexpected challenges) of working in science.

I decided on this topic after I just spent a few minutes clicking through the past week of entries here on Quantum Diaries. There really is quite a lot of information being posted here (including a really nice, detailed description of the Higgs boson, which was useful to me).I’m particularly enjoying Bob Peterson’s description of his journey around the world. We’re certainly covering a wide range of topics.

One thing I did notice is that people are writing a lot of explanations – how things work, how their detectors work, what we’re trying to discover. I think this is really good stuff and I’m glad we’re writing about it, but it does give the impression that we generally know what is going. Unfortunately, my experience, and therefore the subject of this post, is that a lot of the time my experiments do not go as expected and I often find myself rather confused (I suspect that other people have the same experience, but I’ll be safe and speak only for myself here).

First, experimental physics never goes exactly the way you planned it. Something always goes wrong. To give a particularly disastrous example, my lab flooded once in when I was at Yale for graduate school. Most experiments have some form of basic monitoring system called “slow control.” The slow control is constantly taking measurements of the pressure or temperature of a system and reading back to some kind of database. Often, they will be set up to send the experimenter a warning of some kind when a reading is out of safe range – for example, if a pressure gets too high. On this particular occasion, I was running a chamber filled with liquid neon, which is a liquid at minus 248 degrees Celsius (or 25 Kelvin). I think it was a Friday or Saturday and I was out to dinner with a friend when I got a text message – “ALARM: T1 out of range! T1 > 28 K!” – that the temperature was rising and therefore pressures might be getting a bit high. While there was no physical danger due to the safety systems that are engineered into experiments like these, often the safety systems will not protect against the loss of the experimental run itself, which in this case would have cost me several months and delayed my graduating. And I wanted to graduate.

I broke a few traffic laws on the way to my lab (fortunately I was not too far away) and was faced with the scene shown in the picture. It may be slightly hard to tell, but normally there is a large 4-foot by 8-foot pit in the middle, where the stainless steel cylinder is sitting, but in the picture the pit is completely full of water. There is rather a lot of expensive equipment sitting around the room, also in water. I ran down the stairs, shut everything off, found the source of the flood (a plumbing connection that had burst) and prayed that it would be OK; which, thankfully, it largely was. I had managed to shut off the water before it could damage any of the more sensitive pieces of equipment. The only thing that broke was a single fuse in my cooling system, and I ended up losing only two weeks.

That’s equipment failure, and that does happen often. And we try to learn from these incidents to make our experiments safer and more robust (in the previous example, the slow control alarms worked perfectly and a freak flooding accident did no permanent damage) However, at least it’s generally pretty easy to tell when something physical in the experiment has broken down (although the cause can be elusive).

Screen shot of the slow-control system. Credit: Hugh Lippincott

If you’ve been paying attention to recent popular physics news, you’ll have noticed that various “excesses” are all over the place at the moment (in dark matter, at CDF at Fermilab, at the LHC). These are examples of data that we do not fully understand, and we really don’t know what is going on yet.

In the next post, I’ll talk a little bit about the current run of COUPP, which produced some really strange results back in November and December that we’re still trying to figure out.

—  Hugh Lippincott


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