As we were approaching the Tenerife airport yesterday, I suddenly remembered something...
The thing is, I have this weird fascination for accidents and catastrophes (Titanic, bombings of Hiroshima and Nagasaki, the Chernobyl accident, and more or less all accidents from "air crash investigation ") - which is probably one of the main reasons I was interested in nuclear physics in the first place. If you're like me, you might know which thing, or accident, I came to think about as we were approaching the airport? It was of course the Tenerife accident of March 1977, involving two Boeing-747, that crashed at the runway, killing close to 600 people. If you're weird like me, you probably don't think I'm completely crazy for googling the accident. (If you're not like me, you might think I'm insane for reading all I could find about the deadliest air crash ever, just before I'm about to go on a six hours flight :v )
First I found a very interesting and well written article, but after I had read this, and still wanted more, I kept scrolling, and suddenly I saw the two words depleted uranium. I don't think it was from the most serious web page ever, but I was inspired by it to make ten facts about this mysterious material - check fact number 10 for why the Tenerife air crash and depleted uranium have anything to do with each other:
- depleted uranium is what you get when you take natural uranium, and you enrich it to get enriched uranium for nuclear fuel - the "waste" from this process is the depleted uranium (natural uranium minus enriched uranium equals depleted uranium, to sort of make into an equation <3) reason why it's called "depleted" is that it's depleted in the fissile uranium-235
- natural uranium is made by uranium-238, uranium-235, and uranium-234. The uranium-238 isotope makes up 99.275%, uranium-235 is 0.72%, and uranium-234 is just 0.0054%. Depleted uranium is made up by typically 99.799% uranium-238, 0.2% uranium-235, and 0.001% uranium-234
- depleted uranium is often called just DU
- it's the least radioactive kind of uranium: depleted uranium is less radioactive than natural uranium - meaning it's close to not radioactive at all. Uranium-238 has an activity of 12 445 Bequerels per gram, uranium-235: 80 011 Bequerels per gram, and uranium-234: 231 million Bequerels per gram. The total activity of natural uranium is therefore: 25 280 Bequerel from 1 gram (meaning that 25 280 atoms of the uranium - either 234, 235, or 238 is changed into another atom every second :D), and the activity of depleted uranium is about half the activity: typically 14 600 Bequerels per second. (Don't be fooled by long halflifes - the longer the halflife, the less radioactivity... Activity/radioactivity sort of tells us how fast a material is turning into something stable: if the radioactivity is very high, the halflife is short. If it's very very low, the halflife is long. Uranium-238 has a halflife of 4.5 billion years, and is not at all very radioactive.)
the gamma dose rate from a 30 mm DU-bullet (of 271 grams) at a distance of 1 m is 7 nano sieverts per hours, which is almost not distinguishable from the normal background radiation of typically 100 nano sieverts per hour. If you take 10 kg of DU and disperse it over 1000 m2 the result is a gamma dose rate of 4 micro sieverts per year (the average background radiation from gamma in Norway is 0.5 milli sieverts)
- DU is extremely dense, and therefore very heavy. Natural uranium is already a metal of high density, with 18.9 g/cm3, and DU is even more dense: 19.1 g/cm3 - making it almost 70% denser than lead
- because of the extreme density, it's used as ammunition; since a projectile made from DU has a bigger kinetic energy than if it were made by lead, and therefore it will penetrate or destroy almost anything. Also, if a DU bullet hits a tank, all the energy that it's carrying will turn it into dust, and the heat generated will make it burn. If you're in a tank that's hit by a DU projectile - it's not exactly the radioactivity you should fear...
- DU is actually the best kind of shielding you can make to protect yourself against gamma- or X-rays. It's even better than lead, since uranium has 92 protons in the nucleus, compared to only 82 in lead. (You could also shield with natural uranium, but since natural uranium has more of the uranium-235 isotope than depleted uranium, and 235 is more radioactive than 238 and DU, you would rather use DU than natural uranium)
- uranium (thus also depleted uranium) is a heavy metal, like lead, and this fact is the main reason it's not very healthy - not the radioactivity. You take natural uranium, and make into something that's about half as radioactive as it already was. It's not like you make a new radioactive material.
- depleted uranium is also used as counterweight in airplanes like the Boeing-747; that carries around 250 kg of DU. I didn't know this until I started reading all I could find about the 1977 Tenerifie aircrash. I definitely learned something new, and now I want to learn more about counterweights 🙂
Luckily we got home safely after a great week of vacation, and I think I'm ready for a couple of very busy months. I've made a nice plan for this week, that includes talking about cold fusion on the radio tomorrow. Sorry I haven't been "here" last week, but I needed the vacation, and Alexandra needed her mother to be there, on vacation with her, and not on the cell or the computer all the time...:)
No, I'm joking, obviously, but my arms and my back hurt, and my head feels like it weighs a ton. And my eyes are dry and sore. And I'm going back and forth with respect to how to best represent my data and my results - and what to put in this article, and what to put in the next article (and I do remember, very well, that I was accused of self plagiarism one and a half year ago, and I'm of course very scared that someone will accuse me of something like this again, unless I'm extremely careful...:/)
I guess this is #phdlife <3
Since I wrote about my feelings about programming on Thursday, I got some comments and questions about how and why; which can be totally ok, but also a little annoying if it's more like "why on earth are you so stupid you're trying to do anything in C++" (no one said exactly that, it's just an example of a not very constructive comment). Like my friend, Anders (not my boyfriend, but my friend who is a boy - haha), said: "With programming you can do everything! (Except for saying out load which language you are using without someone telling you it's wrong.)"
Telling me stuff like "you have to hate yourself for choosing C++" is not exactly helping me (or anyone really), right? I didn't wake up one day and say to my self "hey, I think I want to program C++ for no reason what so ever - just because I enjoy feeling stupid". I need C++. So it's a little bit like telling your kid who is doing his/her algebra homework "you must really enjoy feeling stupid since you're doing this algebra stuff - you should work on statistics instead".
I love getting constructive comments or critique, but some comments are just making me feel more stupid than before (like: not only am I not managing the programming stuff, I'm also an idiot for trying to learn what I am learning...).
So I thought, today I want to give you ten FACTS about experiments and data analysis here at the nuclear physics group in Oslo - which is the main reason why I need any knowledge of programming these days. This is probably the geekiest (and perhaps most "technical") facts post I've had so far...but sometimes you have to be a little geeky, right? 😉
- The material we want to study can be almost anything - for example uranium, gold, nickel, molybdenum, iron, dysprosium, thorium or plutonium (these are just some examples of what we have experimented with the last couple of years)
- We make a tiny foil - a target - from the material (almost the size of a small coin), and put this inside all of our detectors
- There are always at leas two types of detectors for the experiments: Sodium Iodide detectors (they measure gamma rays), and Silicon detectors (they measure particles)
- The Sodium Iodide detectors are called CACTUS (cause it really looks like a cactus) <3
- Sometimes we use more detectors than the gamma detectors (CACTUS) and the particle detectors - for example fission detectors (we used that for my uranium experiment, since uranium-233 fissions like crazy 😛 )
- To study the nuclei in the material we bombard the target with tiny particles; protons, deuterons (a proton and a neutron), helium-3 (two protons and one neutron), or helium-4 (two protons and two neutrons - same as an alpha particle 😀 )
- When a particle hits a nucleus in our target material, the nucleus gets some extra energy (sort of like it gets heated); then a particle goes out (it can be the same that went in, or it can be another one), and the target nucleus cools again, by sending out gamma radiation
- The different detectors will detect the different kind of stuff that comes out from the reaction in the target: the gamma detectors detect the gammas, the particle detectors detect the particles (protons, deuterons, helium-3, or alphas), and the fission detectors detect fission - the detection of all these thing are what we talk about as our data
- Data from the experiments we are performing in Oslo (like my uranium experiment) is typically 10-100 Giga Bytes - so it's kind of a lot
- To sort all of these data we need codes/programs that go through everything and checks if there for example was a particle and a gamma that came out of the target at the same time, or maybe it was a particle and a gamma and a fission product, and what were the energie
s of all this; the particles and the gammas - on the lucky side I don't have write theses sorting codes from scratch, on the other side I have to try to understand someone else's code and logic, which is not always very easy (when I don't understand I'm always sure it's because I'm stupid :/ )
- CACTUS <3 -
The sorting codes, and everything else I'm working on is written in C++, and that's the reason why that's the language I'm working on.
Happy Monday to everyone!
Meaning another week with my plot... Obsessing about my plot. Trying to make it just perfect. Try different colours. Different styles. Obsess - science style.
On Friday I was actually thinking that this is it, that I was finished with this part of the data analysis; but then, today, I realised that other people have done similar things (analysed other uranium nuclei, for example), and that they have put five of those black pumps in the plot, instead of just four - so now I'm thinking about doing the same thing.
As you can see I've added more colours to it now; there's another, lighter pink colour, a yellow-orange'ish colour, and the uranium-235 is bright green - since someone suggested that as a colour 🙂 Maybe you have suggestions for the black bumps? They don't have to be black...;)
Right now I'm having a glass of wine with supervisor Jon - he's here for the week, and in addition to obsessing about this plot, I've shown him where I am in the entire analyse thing. We looked at a couple of other plots too today, and he said that there's definitely a cool paper in there...:D (Of course we don't know for sure yet, but I choose to be optimistic <3 ) If you follow me on Snapchat (I'm sunnivarose, of course), you've seen the plot that Jon was so excited about.
Today I've spent time at the EXFOR database
- hate it and sort of love it at the same time...
So far it's the "worst" database I've visited, but so far it has also given me what I've needed *mixedfeelings*.
Then I've worked on my strength function plot, which is starting to look like something now. Tomorrow I hope to tweak it so that it will be ready for my next article 😀 #phdlife
Here are some details of today's plot:
//this may sound silly; but I was so proud of my self when I managed to make these labels (no, I do not love ROOT - yet) 😛
//this has to be fixed - the slope of the square points needs to be more in line with the two sets of triangles (task of tomorrow!)
Good morning everyone <3 Day two of this California/Berkeley trip has just started, and so far I'm very happy 🙂
Yesterday I "finished" the first part of the uranium analysis (which is to find the nuclear level density
of uranium-234) - that I wrote about in my last blog post
- and started the second part of the analysis (which is to find the gamma ray strength function
of uranium-234). The picture above show the very first result of my gamma ray strength data (the squares - both black and white) plotted together with different data from the big nuclear data bases. When I wrote "plot" and this appeared I actually screamed with excitement and joy, and hugged Cecilie, who was sitting next to me and helping me, because it looks soooo pretty - even before I've started to "tweak" my data to fit with the ones from the data bases (the ones on the right side of the plot - the little triangles).
The goal of this trip is btw to put these two properties of the nucleus (the nuclear level denisty and the gamma ray strength function) into simulations of different reactors (that uses thorium based fuel) and see if they affect the results of the simulations - when we compare to standard simulations where we don't do anything about these nuclear properties 🙂 *excited*
Below are a couple of pictures from yesterday and today. The first one, of Anders, is probably more like what you would imagine when I say "pure joy"...;) He has just rented a nice car and is on his way to Palo Alto as we speak - he is also excited. (Actually kind of wish i could go with him, but I'm on my way to the lab now, with Cecilie - and that will of course also be fun...but in a quite different way 😛 )
beautiful morning at Berkeley campus
cutest squirrel at Berkeley campus
Cecilie and Darren discussion something important (I'm guessing 😉 ) at Jupiter, where we had dinner yesterday - and the day before, when we'd just arrived
It's official: Cecilie (my fantastic and talented colleague) and I are going to Berkeley, one week in August!!!
It is of course for working (but who doesn't want to go to Berekely and work there, huh?!?), so the trip basically takes away (big parts of) my summer vacation, since I have to do a lot of preparations before we go - or else I have really no reason to go, since it wont help to go there unless I have my results that I need to get more results 😛 On the other hand, this trip will (hopefully) enable me to write my third paper, and if so, I'll be a GIANT LEAP (like, really) closer to my degree, so I think losing a summer vacation will definitely be worth it!
I have some plans for that third paper (article) that I'm not yet ready to share with you - but I'll do it later, when I know more about how it will go...;)
We're flying with Norwegian, directly from Oslo to Oakland (which is even closer to Berkeley that San Francisco - where we normally fly to), and it will be so nice not to change flights somewhere. Also I'm excited about flying Norwegian on such a long-distance flight - wonder how it will be...:)
Not even a teeny tiny step for mankind.
(Possibly) a small leap for me - today I did this <3
This means that I've (probably) figured out the gamma radiation, well enough so that I can calibrate my gamma detectors - and then figure out the rest (*playing puzzle*). I'll know more tomorrow...
I'm quite satisfied, though, since I'm really moving forward - even though I'm moving forward one very small step at the time 😉
PS: Check out the new page I made for Sushi and Nuclear 😀
PPS: For my fabulous Norwegian speaking readers; the talks from yesterday's "Women in Tech" conference can now be seen HERE
- so proud that I was part of that event!
I admit it; I'm feeling stressed.
Our nuclear physics workshop/conference here in Oslo, where I'm supposed to give a talk (and show RESULTS) is only three weeks away, and my gamma detectors are not yet calibrated. Don't get me wrong: it's not like I'm giving up (I don't think I'm a quitter), but I know there is work to be done. I think I have to go through my plan, and check how I'm doing with my milestones/goals - I'll give you an update tomorrow <3
I think I could have worked faster, but I really really want to understand this - and make sure I make NO MISTAKES! So today I made this table, and the next step is to try to find the different gamma energies from the table and place them in the plot...hope my "prework" will pay off, and that tomorrow will be successful day 😉
So this beautiful table shows the different Q-values for the different reactions that go on in my experiments (oh, yes, there's beryllium and there's carbon and there's oxygen there - even though it would've been nice if it was only uranium...).
The Q-value tells how much energy that is released in a certain reaction: for the first reaction, for example, the Q-value is 4620 keV, which means that when a deutron hits a uranium-233 nucleus, and a proton goes out of that reaction, around 4600 keV (energy) is released ;). If that same deutron hits an oxygen-16 nucleus instead of the uranium-233, and a triton (instead of a proton) is released, the reaction absorbs energy instead of releasing energy: 9406 keV to be (almost) exact...
I also, finally, submitted my application about changing my theoretical curriculum for my PhD degree 😀
It's beautiful at the University these days, btw - don't you agree? Love blossoming cherrytrees:)