Ten facts about depleted uranium

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:

1. 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 
2. 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
3. depleted uranium is often called just DU
4. 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.)  
5. 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)
6. 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 
7. 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...
8. 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)
9. 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. 
10. 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...:)

References, figures, and references

...and figures.

And tables!

FML.

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

Facts on Friday (we pretend Monday = Friday) - EXPERIMENTS!

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? ;)

1. 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)
2. 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
3. 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)
4. The Sodium Iodide detectors are called CACTUS (cause it really looks like a cactus) <3 
5. 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 :P )
6. 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 :D )
7. 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
8. 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
9. 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 
10. 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 energies 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!

Obsessing...

Monday!

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...;)

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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.

kPink+7

Remember my plot from yesterday? And how happy and proud I was because I managed to make labels for the different data?

Well, today I learned (from Gry - thank you, sweetie <3) how to make it pink - and by my self I found out how to make it the exact right kind of pink. It's called kPink+7 <3<3<3, and it's just perfect, and if you think that I'm not "brave" enough to use this colour for my uranium data in a scientific article, you're wrong ;)

Yeah, and also I did the tweaking of the data points as I also talked about yesterday (I didn't spend all day on making pink data points :P)

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Speaking of pink; tomorrow I'm going to be a guest at God Morgen Norge, together with Kathrine Aspaas, who has just written a book called Rosa er den nye pønken - tune in between nine and ten (I'm guessing something like nine thirty, but I'm not 100% sure).

PS: What other kind of colours should I use in the plot?

Data, data, and more data

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 :D  #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) :P

 

//shapes <3 

 

//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!)

Pure joy!

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*

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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 :P )

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

Jupiter <3

Jupiter <3

Berkeley baby!

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 :P 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...:)

Collapse

I'm dead tired right now... After I held my talk yesterday (outfit above; trying to "be me" but just enough "conservative" at the same time) I felt like I just collapsed (I managed to take part in the conference dinner, luckily :P ), and this morning I just slept through my alarm - which never happens, except maybe if my body is trying to tell me a needed a couple of extra hours sleep. I've been really stressed about the talk yesterday, and the (preliminary) results that I showed was finished on Wednesday afternoon. Being so "last minute" didn't exactly feel great, and that was probably one reason why I was so nervous.

It has been a great week though; and even if I really  just want to go home now, and go to sleep, I'm going out with all my great nuclear physicist colleagues from all over the world <3

Wishing everyone a great Friday and a great (long) weekend!

(from my snap chat story - follow me at sunnivarose ;))

- in action -

Getting there...

My talk is tomorrow.

It's not finished yet.

I feel nervous, but also excited...

Nervous, because I wish I had come further than I have, and that I understood "everything". Excited, because I actually do have results, and they are nice, and they make sense. They make me believe that I will actually do this; not just the talk tomorrow, but I will finish my next paper (article/publication) in June (or maybe July - but hoping for June). After that I will start directly to analyse the second part of the uranium experiment, and hopefully it will be much "easier" since I have already done it once ;) 

I'm in my bed right now, working on the presentation for tomorrow, which is around 11. Think I will work for around 30 more minutes, and then go to sleep. I'd rather get up at 5 tomorrow morning, and finish it then.

Wish me luck <3

Happy face

I'm so relieved right now...! It turns out I've (probably) done a good job when I've calibrated my gamma detectors - and now I'm actually getting real results.

It's preliminary, of course, but it's there - something I can actually show in my talk at the conference here in Oslo next week (that I've been so nervous and stressed about :/ ).

There is still tons of work to do, but I must admit I'm really happy and motivated for everything right now; nothing can stop me, and the rest of 2015 will be about analyzing data and writing papers...<3<3<3

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Here are some happy pictures from yesterday (spending a day off with Alexandra) and todays celebration of 17th of May in kindergarden - just love Biørneblæs, the student marching band!

Happy weekend and 17th of May (for those of my readers that celebrate such things) and everything!

TGIF <3

Finished...!

...in several ways...

Finished with the calibration of the gamma detectors (happyhappyhappy :) ), but now I'm also "finished" mentally :/

Started this day by oversleeping (not the best start of a looong day), then I gave a talk about nuclear power and radiation at the biology department, and after that I've been working at Gry's office (she helps me A LOT <3) and my own office.

me, ready (sort of) for talking to the biology students - wearing one of my favourite dresses from HM, and of course heels  

After spending a couple of hours fine tuning my gamma detector calibration, I made this plot - showing gamma radiation from oxygen and beryllium. It looks like the peeks are only 20-30 kilo electronvolts "off", and I think that's ok (I'll ask someone with much more experience than me tomorrof, of course!).

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So now I've started to look at time correction stuff - having "fun" with staring at these different graphs. If they look the same, I can tell you they're not, but it's definitely not easy to see which one is "best". At least not for me...

After a good night's sleep it will probably be clearer when I can discuss this with someone (Supervisor Sunniva? ;) )  tomorrow - meaning; I've been at the University for 12 hours, and now it's time to go home <3

Coffee and (DARK!) chokolate

Good morning!

I forgot it takes forever to get from Charles de Gaulle airport, north of Paris, to the lab in Orsay, south of Paris... Normally I prefer to fly Norwegian to the Orly airport, which is just between the city and the lab, but this time Air France was the only company with reasonable flight times. Anyway, by the time I finally arrived at the lab, I was starving, and had to get something to eat. Then there was catching up to do, and suddenly it was 10:30 PM and I had to go to sleep because I had signed up for the morning/day shift today. I´ve been at the lab since 7 AM, and heavy doses of chocolate and coffee are needed ;)

(Didn´t have time to put on my make up this morning btw., so I look a little...hmmm...don´t really know...:P )

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So I told you yesterday that I was embarrassed, and that I would tell you about it - was planning on doing it last night, but now you know how come that didn´t happen. I will tell you now instead:

Last Friday I was on the radio, and one of the things I was talking about was the amount of radioactivity that was present at earth 3.5 billion years ago (when life started). So I was talking about the half-lives of thorium-232, uranium-238 and uranium-235. 

Thorium-232 has a half-life of 14 billion years, so the amount of thorium here on earth is more or less the same as it was 3.5 billion years ago. The half-life of uranium-238 is 4.5 billion years, so around half of what was here 3.5 years ago is gone.

So far, so good...

But then I talked about uranium-235, which has a half-life of "only" 700 million years. This means that 3.5 billion years is more or less the same as 5 half-lives of uranium-235. Then I did the mistake: I said that since 5 half-lives of this uranium isotope has gone by, there is one fifth of it left - in other words, 3.5 billion years ago there was 5 times as much uranium-235 on earth, as it is today.

WRONG! 5 half-lives doesn´t meen that there was five times more :/ *feeling stupid*

1 half-life of something means that after that time half of it is gone. Two half-lives means that 3 quarters is gone, three half-lives means 7/8 is gone, four half-lives means 15/16 is gone, and five half-lives means 31/32 is gone - 1/32 is left. 1/32 is around the same as 3%, and 3.5 billion years ago there was 32 times more uranium-235 on earth...!

My excuse is that I was really stressed the day before, and something did NOT feel right (e.g. I didn´t get the right percentage of uranium-235 to have fission and a chain reaction going on in nature - and now I know why :P ); but this was a "rookie mistake" - and I shouldn´t have done it :(

Hope you can forgive me <3 <3 <3

Tomorrow is an important nuclear anniversary - anyone that can guess what it is? I will tell you tomorrow :)

Number 18

So, in the calendar today there are gammas (gamma radiation) - I´m giving you an ALFNA matrix :D xD <3

The ALFNA matrix/plot is a sort of 3 dimensional plot where there is the excitation energy of some nucleus (we don´t know which one - and this is what we/I try to figure out) on the y-axis, and on the x-axis is the energy of the gamma(s) the nucleus sends out. The thing is that when a nucleus is hit by a particle, the nucleus is excited, or sort of heated - it gets some extra energy, and to get rid of that extra energy it sends out  gamma radiation. 

From earlier experiments that have been done (the bible is here) we know quite a lot about what kind of gammas (which energies) the different nuclei will emit when they are excited to this and that energy. In this particular ALFNA matrix we believe that we have oxygen-17 (there is always some oxygen :) ) and beryllium-10 (the backing of the uranium foil/target is made from beryllium). The oxygen-17 peak for example, is supposed to emit a gamma ray with an energy of 870 kilo electron volts (keV), and here it is at around 1300 keV - which means that we are quite off, and everything needs to be calibrated (which is exactly what I´m working on now ;) ).

So this is the plot I´ve been staring at today (together with my supervisor, Sunniva <3). 

...and I´m staring even more now (pretending to have a really huge brain) - looking like this :P

Number 15

Only 8ish days ´til Christmas now...and in todays calendar is another cross-section graph - this time it´s the cross-section/probability of neutron capture on uranium-233:

On the y-axis is the value of the cross-section (the higher the number, the higher the probability of a neutron being captured by the nucleus when hitting it), and on the x-axis is the energy of the neutron.

But there are several graphs here...and they all show different values for this cross-section - the truth is that we don´t exactly know what it is (my research is into this...) :/ The blue, turqoise and red lines are the "official numbers" (evaluated nuclear data), the different dots are actual measurements (some with HUGE error bars), and the green line is calculated with the default input parameters about the nucleus.

It´s quite an important cross-section for the thorium fuel cycle, since it tells us about the probability of a neutron being captured by uranium-233 instead of making it fission (which is what we want it to do) - so it would be nice to know it better ;)

13 + 14

So, yesterday I didn´t get the chance to share a graph, so today you´ll get a double dose :D

Also, I got a complaint that the last graphs didnt´have any christmas decorations on them - so I´ve tried to do better this time...;)

Today you get two versions of ALPHA! 

ALPHA is the "capture to fission ratio" - it tells us how often a neutron is captured/absorbed, rather than causing a nucleus to fission. We want ALPHA to be as low as possible - since a low ALPHA means that little waste is produced :D

First there is ALPHA for neutrons with low energy:

The red line is for uranium-233, and the blue is for plutonium-239. For low-energy neutrons, ALPHA is lower for uranium-233 than plutonium-239, and this means that there is a smaller waste production from thorium-fuels than uranium...IF the neutrons have a low energy/are thermal (this can´t be said often enough ;) )!

Then there is ALPHA for neutrons with high energy - and here it changes (as it also did with ETA):

For neutrons with high energy the waste production is smaller for uranium-fuels than with thorium...