Well, I got voted off of I'm A Scientist. Never mind! It was good fun trying to answer all the questions, and chatting to school kids about science. And hats.
This post serves to provide something for anyone who still didn't get a chance to ask me questions in the competition to ask me, now that I'm out. Please feel free to comment with questions!
Thursday, 25 March 2010
Wednesday, 24 March 2010
Survived the first eviction
Well, I survived the first eviction. Woo! I feel a bit bad for Sarah, though. What she does is really interesting, but I think computer science is a harder sell than disease-curing biosciences, or gee-whizzy space stuff. I hope she prompted some of the kids to think about things like computer science as proper science. She pointed them to Project Euler, too, and maybe some of the more keen ones will get started with the problems there. Which reminds me, I should try some more of them too. My solved problems page is looking a little weak.
Saturday, 20 March 2010
Get me out of here?
We're half way through I'm a Scientist Get Me Out of Here. From Monday, the students will start voting us off. Eek! Hopefully I won't be gone on the first day. They've just fixed the website so that you can see all the questions that we've been asked and what answers we've given. Mine are here. It's sort of a shame, but completely reasonable, that people not in the competition can't comment. Feel free to comment here though :-)
Monday, 15 March 2010
I'm A Scientist Get Me Out Of Here
The two-week run of I'm A Scientist Get Me Out Of Here started today, and I've had quite a few questions from the kids taking part so far. Have a look at the lithium zone on their site to see what questions I, and the other scientists, have been asked. It's been pretty interesting to find out what sort of things the student are interested in. Everything from "was it really hard work to get where you are now?" to "do you harm animals in your work?" (quick answers: kinda and no)
Tuesday, 2 March 2010
The new alchemists
One of the cool things doing nuclear physics is that it has realised the old alchemists' dream of turning lead into gold - or indeed any element into any other. While one of my colleagues has genuinely turned lead into gold, some of the most exciting work in nuclear physics comes from trying to make new elements.
The chemical elements start with element 1 - Hydrogen - with one proton in the nucleus, then on to element 2 - Helium - with two protons and so on. The heaviest element that you can dig out of the earth (in trace amounts) is Plutonium, with 94 protons. Beyond lead (element 82) all known nuclei are unstable against decay into lighter nuclei with characteristic lifetimes ranging from tiny fractions of a second to many trillions of years. As one gets, though, to heavier and heavier elements, the lifetimes get shorter and any nuclei heavier then plutonium that might have existed on the Earth have long decayed. This doesn't stop us trying to make new elements in the laboratory, though, to better understand the forces between neutrons and protons, and to try to understand what isotopes may have been made in nuclear reactions in stars.
These "superheavy" elements are made by colliding two lighter nuclei together and hoping that they fuse together. One then looks for the alpha particles that come from the decay and the resulting residual nucleus which one can hopefully identify as a known nucleus. Indirectly, by studying the decay chain, one gets a "genetic fingerprint" for the original superheavy nucleus. Recently, however, a group based at the GSI facility in Germany has actually measured a superheavy nucleus' mass directly, rather than by inferring it from the decay. By trapping it in a magnetic field and observing how fast it oscillates round the trap, one can determine its mass very accurately. Knowing the mass is important, as it is a measure of the stability of the nucleus. This helps us point to the possibility that there is a more stable region of superheavy nuclei inaccessible to experiment as yet, but containing nuclei long lived enough to make an appreciable amount of material from.
The work is published in Nature, and the IoP's Physics World blog has already reported it. It's perhaps not as earth-shattering, but before the Nature paper appeared, a PhD student of mine, and myself submitted a theoretical paper on the likely appearance of especially superheavy nuclei with very large numbers of neutrons. Fingers crossed the referees will return with positive comments!
The chemical elements start with element 1 - Hydrogen - with one proton in the nucleus, then on to element 2 - Helium - with two protons and so on. The heaviest element that you can dig out of the earth (in trace amounts) is Plutonium, with 94 protons. Beyond lead (element 82) all known nuclei are unstable against decay into lighter nuclei with characteristic lifetimes ranging from tiny fractions of a second to many trillions of years. As one gets, though, to heavier and heavier elements, the lifetimes get shorter and any nuclei heavier then plutonium that might have existed on the Earth have long decayed. This doesn't stop us trying to make new elements in the laboratory, though, to better understand the forces between neutrons and protons, and to try to understand what isotopes may have been made in nuclear reactions in stars.
These "superheavy" elements are made by colliding two lighter nuclei together and hoping that they fuse together. One then looks for the alpha particles that come from the decay and the resulting residual nucleus which one can hopefully identify as a known nucleus. Indirectly, by studying the decay chain, one gets a "genetic fingerprint" for the original superheavy nucleus. Recently, however, a group based at the GSI facility in Germany has actually measured a superheavy nucleus' mass directly, rather than by inferring it from the decay. By trapping it in a magnetic field and observing how fast it oscillates round the trap, one can determine its mass very accurately. Knowing the mass is important, as it is a measure of the stability of the nucleus. This helps us point to the possibility that there is a more stable region of superheavy nuclei inaccessible to experiment as yet, but containing nuclei long lived enough to make an appreciable amount of material from.
The work is published in Nature, and the IoP's Physics World blog has already reported it. It's perhaps not as earth-shattering, but before the Nature paper appeared, a PhD student of mine, and myself submitted a theoretical paper on the likely appearance of especially superheavy nuclei with very large numbers of neutrons. Fingers crossed the referees will return with positive comments!
Thursday, 25 February 2010
I'm a scientist, get me out of here!
I'm rather excited, as I've been picked for the next installment of "I'm a Scientist, Get Me Out of Here!"
I'll have to try to enthuse various groups of school kids about what I do, and in a better way than my competitors. Should be lots of fun, if a little daunting. Details of the competition are here. I'm up against a range of other scientists, doing lots of interesting sounding things. Now I have to think of all the reasons that nuclear physics is really interesting...
I'll have to try to enthuse various groups of school kids about what I do, and in a better way than my competitors. Should be lots of fun, if a little daunting. Details of the competition are here. I'm up against a range of other scientists, doing lots of interesting sounding things. Now I have to think of all the reasons that nuclear physics is really interesting...
Sunday, 21 February 2010
TTFN, BBFH
Nuclear Physics is not an isolated subject, but influences, and is influenced by other areas of physics, other scientific subjects, and wider society. One of the strongest and closest scientific links is in astrophysics, since stars are nothing but giant nuclear reactors. This realisation - that all elements heavier than lithium were created in the stars - does not go back to the days when the chemical elements were identified as such, or when it was realised that the elements are made of atoms with tiny nuclei at the centre. They were both pre-requisites for astrophysicists to finally understand what powers stars, namely nuclear fusion. The bulk of the puzzle was not solved until the 1950s (and indeed the entire picture is still not known) when a seminal work by Burbidge, Burbidge, Fowler and Hoyle was published which laid bare most of the nuclear reactions that occur in stars, converting lighter elements to heavier, and responsible for all the heavy elements in our bodies ("we are all stardust.") Last month, one of the co-authors of the famous paper died. Though he wouldn't have called himself a nuclear physicist, he helped define the field.
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