6.18pm. Okay so I was a bit tired when I wrote the last blog entry and there wasn't a huge amount of content there. It's actually quite hard to put much into a blog entry when you are typing it text message-style on a mobile. But I think we can do better than what I actually wrote. So...
Just before lunch, we set a Geiger counter running to measure the background radiation of the lab, so that we could do some calculations and take the background radiation into account.
Over the course of 101 minutes the counter registered exactly 2,000 counts (we waited until it got to a nice round number!), giving a mean background count of 20 ± 1 per minute.
We then tested a uranium-rich mineral sample, and that gave us 134 ± 13 counts per minute.
A second source called a caesium/barium isotope generator was then used. In this heavily encased source, a radioactive isotope of caesium decays to barium, which is itself radioactive. In this experiment we were looking to see what the effect on the radiation could would be if sheets of lead of varying thicknesses were added.
These were hooked into a short pole attached to the top of the Geiger counter, and we started with the greatest thickness first. This meant that it was easier to run the experiment quickly, as we could simply use a pencil to separate one of the lead slices and slide it off the metal pole, to remove it from the field. As the thicknesses decreased, so the readings from the counter got higher.
To give you an idea of the difference, 20mm of lead resulted in a count of 11 ± 7, whereas with no lead sheets present the count was 126 ± 13.
I enjoyed this experiment very much, it was a good, systematic experiment with results that could be shown visually on a graph.
We had a short coffee break, and I sat practically open-mouthed listening to a Scottish girl from another group whining on about the amount of detailed instructions being given to operate a microscope, which sounded like the biology Activity D that we did yesterday. I can't bear people who moan and belittle everything. If you don't want to be here, sod off, frankly.
After the break, we did a further experiment with the caesium/barium isotope generator. This experiment involved flushing a solution of a cyanide compound through the generator. The barium product in the generator is soluble, thereby rendering the liquid that is released into a tiny collecting jar radioactive, with the released barium. This enabled us to study just the barium without the results being skewed by the more powerful caesium.
The barium was relatively weakly radioactive, with a first count of 102 ± 12, however after only 8 minutes it had dropped to 17 ± 8, which is within the realms of the background radiation, thereby rendering the remaining results a little randomised.
This did however enable us to calculate the half-life of the barium product, which 2.55 minutes.
The session was then rounded off with a briefing about radiogenic heating, i.e., how the heat from the interior of the Earth is comprised of two things, firstly heat generated by radioactive decay, and secondly from primordial heat 'left over' from the creation of the Earth all those billions of years ago.
Felt a little tired by the end of it. Kirsten (who flirted outrageously with blue-eyed Steven all day) said that she needed some time off campus, so she's gone to Lewes for a little while. Sounds like she has a touch of cabin fever.
I dashed back to my room, dumped my notes, lab coat and stationery, and went to dinner. Dinner tonight was some kind of pie, cauliflower cheese and what I can only describe as coleslaw made with purple stuff, God knows what that was but it tasted fine.
To be honest I could do with an evening off. But Keith Moseley is running a session called 'Observing The Universe' at 8.15pm. As I suspect this will tie-in with SXR208 (Observing The Universe, the Mallorca residential) I feel obliged to go, to get the best idea of what I am letting myself in for.
However tomorrow there are no optional tutorials that really catch my eye, so I intend to have the entire evening off, and to get off campus, finally. Like Kirsten I am starting to get a serious case of cabin fever, as I have seen the inside of about four buildings only since Saturday. I seriously need to breathe some sea and and see something different, other than into the insides of the bedrooms on the next court of Swanborough.
A bedroom with a view
6.51pm. Just got off the phone from Alan, a blissful 18 minutes of lovely conversation, hearing what he's been up to back in the Midlands. I have been missing him quite badly today. There are however just two full days left to go, and if the days this week that have gone by are anything to draw conclusions from, they should fly by too.
I am looking forward so much to throwing my arms around him on Friday. Kirsten has offered to give me a lift into Brighton on Friday lunchtime, which is kind of her.
More later... off to put my feet up for a bit and get ready for the session later.
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