Bye bye Berkeley!

...and hello Oslo :)

Here are some snaps from a great trip.

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...

The 12th of December

Today is December the 12th, and in the calendar is the rest of what I gave you yesterday - it´s ETA again, but this time it´s ETA for neutrons with high energy (fast neutrons). The graph is very important for the neutron economy of a nuclear reactor...

ETA tells us about how many neutrons you get out for each neutron going in (to a nucleus) on average ("neutrons emitted/neutrons absorbed"). As you can see you get, on average, more neutrons from fission of plutonium-239 (blue line) than you get from uranium-233 (red line) - if the neutron going in has high energy/is a fast neutron. In other words: it´s exact opposite of what was in the calendar yesterday...!

So, since plutonium-239 is a better fissile material than uranium-233 (when hit by high-energy neutrons), you can produce more new fissile material from uranium, than you can from thorium :D Or, to sort of conclude: for thermal neutrons, thorium seems to be the way to do it, bur for fast neutrons, uranium/plutonium seems to be the way to do it <3<3<3

Number 11

In the calendar today is a graph that is very important for the thorium fuel cycle... 

Today I give you ETA!

ETA tells us about how many neutrons you get out for each neutron going in (to a nucleus) on average ("neutrons emitted/neutrons absorbed"). As you can see you get, on average, more neutrons from fission of uranium-233 (red line) than you get from plutonium-239 (blue line) - if the neutron going in has low energy/is a thermal neutron.

So, since uranium-233 is a better fissile material than plutonium-239 (when hit by low-energy neutrons), you can produce more new fissile material from thorium, than you can from uranium :D We like that <3<3<3

Number 10

In Berkeley it´s 3 PM December 10th, so it´s not too late with todays calendar graph ;)

In the calendar today is a very important and very preliminary plot - of the gamma ray strength function of uranium-234. Inside the heart is a little "bump" that is actually really important, and you will get a much better plot of this later (when the analysis is finished) - and also an explanation of what it is...but be patient, and remember that the advent season is about waiting ;)

December 9th

In the calendar today there´s a super nice graph I didn´t make myself, but I have of course made it even prettier than it already was ;)

Todays graph is a so called "cross section graph" for uranium-235.
The cross section sort of tells us about the probability that something will happen to a nucleus; in this case it´s about the cross section/probability that uranium-235 will fission <3 

On the x-axis is the energy of the neutrons hitting the uranium-235 nucleus, and on the y-axis is the cross-section. As you can see the cross-section is much bigger for low energy neutrons than for high energy neutrons - this means that there is a much much bigger probability for a nucleus to fission when it is hit by a neutron with really low energy.

December 8th

Since I´ve sort of travelled through time (at least that´s what it feels like) and now am in Berkeley I though todays advent calendar should be about why I´m really here :) So today i give you fission! 

Yes, again its´fission of uranium-234. This time its´gamma radiation from fission (there is always gammas when a nucleus fissions, and here you see 765 914 gammas at one time xD ), in opposition to a couple of days ago when I showed you particles from fission. 

Both of the axis are energy: The x-axis is gamma-energy (so energy of the gammas that are emitted), and the y-axis is excitation energy (energy of the nucleus before it fissions - the nucleus gets so excited that it just has to split in two :D )

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PS: I think time is very fascinating... here is a picture of me in on of SAS´ time capsules, just after we reached Canada. I´m looking down, around 12000 meters, at snow, and ice, and snow, and snow, and ice :P 

PPS: I think it´s just EXTREMELY fascinating and almost crazy that we can actually get a plane in the air - love it <3