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Free Electron Lasers

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Automatisierte Medienanalyse

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that was and
it is and and uh and the without the chose X. F. E. L. x-ray free electron lasers from what's what's that good yeah something something like that it's just a little bit of a shorter wavelength and it doesn't definitely fits the size of a pen well person here let's is a physicist working at the Deutsche electrons encode on in Hamburg and he knows the answers to that the and he's going to introduce us to this world of free electron lasers and their applications were more come to Dawson's had their hand here have didn't quite know this not only because of this thing but also because my computer broken I get is about 1 hour ago and I don't know if the presentation of that as well but let's hope for the best the despite that I'm very happy to see that so many of you are interested in particle accelerators and I have to say that this is not a direction relations I talked to many colleagues at easy and also in the US and all of them literally knew about this Congress and most of them even knew that was going to happen in like take this year so I think I can say that at least every particle accelerator physicist I know likes to CCC as well and is interested in this Congress the OK but maybe enough small talk from all let's get to some signs so while you're watching this talk young neurons firing incessantly sending electrical impulses to the neighboring neurons but how does this work I mean what other neurons made of while this artist you from Harvard University lets us have a look inside so inside each neuron there's an enormous variety of proteins big macromolecules each consisting out of hundreds of thousands of atoms the of up to 40 % of the volume of each cell is occupied by these proteins and by the DNA serves as a blueprint the proteins are manufactured somewhere inside the cell and then have to be transported to the destination where they are needed for example membrane proteins have to be transported to the outer shell of the cell right and this is done by the so-called vesicles like the blue fill you see over there so the protein stick on them and then mortal proteins like this can a senior posts pick uh vesicle along these long molecular strands which bond through the cell here the green 1 the I don't know if you've seen such an animation before when I saw this movie for the 1st time and when I realized about the enormous complexity of the molecular basis of life this was literally breathtaking to me but have you ever wondered how do we know about this I mean how do we know about the structure of this can missing protein and the answer is uh synchrotron light sources so the last majority of these proteins have been resolved In the latest third-generation synchrotron light sources in this talk I will show you what it takes to build such a machine and how to make a picture but then the next question is how do we know about the dynamics so how do we know how the how these proteins fold and to be honest we have no fucking clue so I don't get fooled by the name of at University of this is just an artist you and we have no idea hold protein folds no 1 has ever seen something like this all witnessed a chemical reaction but by the end of this talk I will have shown you that just by now we have a machine at hand the X-ray free-electron laser which might be able to resolve these proteins within the natural timescale of a couple of and 2 seconds but OK to start numbering
everyone on the same page so I have to recall the electromagnetic spectrum yeah surrounded by a variety of electromagnetic waves which can be categorized according to their wavelength into different other ways for example radio waves with a couple of meters or more in wavelengths then we have the microwaves some centimeters and then the infrared and visible light with a couple of hundred of nanometers in wavelength the if we decrease the wavelength further we will get to the ultraviolet and then finally at 0 . 1 1 0 meter or 1 angstrom we have X rays OK and there exists a fundamental limitation if you want to observe something with electromagnetic radiation namely the diffraction limit so it says basically that if you want to resolve to objects with the distance D and then you have to use the wavelength which is in the order of that distance or smaller so if you want to study of non and or a bacteria you can use visible light because visible light has a wavelength smaller than the size of these objects but if we want to study viruses or the proteins we just saw or even smaller molecules we have to use x-rays but actually always of making a picture from something that small is quite different from what you will use to with your eyes only a camera so we do X-ray ray diffraction images and before I can show you how that works
I have to tell you something about coherence so we start with an ordinary light source which emits light in different wavelength which is you indicated by the different colors and the origin of these wavefronts is spread out OK so we have no fixed face to face relation at 1 point in space and this we call incoherent light that's the kind of light we all surrounded by you may know from high school physics that place an aperture in here then the way France propagate as they would be emitted by a point source in the whole of this aperture and now we have a fixed face relation at 1 point in space and we call this spatially coherent light and the next step towards coherence is sent to put a filter in which lets through only 1 particular wavelengths OK so now this is coherent light and if we consider ourselves to be very far away from the source we can consider these ways to be plane waves and then if a play something for example a double slit in here I would get the interference pattern downstream and on the screen I would be able to detect detect uh diffraction pattern and a tool is now that mathematically there exist the relation between the diffraction pattern in the physical arrangement of these objects so I am able if I know the diffraction pattern and I know the distance between the screen and the object unable to calculate from the diffraction pattern uh the physical arrangement of these objects In all cases we doing ray diffraction so we we don't have double slits but we have electrons on which the photons get scattered and to give you an example this is a
microscopic image from a sample which was hit by an X-ray laser pulse and this is the diffraction pattern you regard at the screen at a detector to so it's a bit more difficult than the previous example but the key is this is the reconstructed image so from this you are able to calculate this 1 these 2 although this is not very intuitive are mathematically equivalent OK we can calculate this from the defective pattern without knowing the original the original sample and this kind of X-ray diffraction
images have been carried out for many just to give you 1
example of the um discovery of the DNA structure was only possible because Rosalind Franklin Franklin made these diffraction images of the DNA crystal injustice side story I guess who got the nobel prize for this course 2 white men but this is not a nasty story I recommend you to look up afterward so the thing is about these X-ray tubes they're very limited in brightness and this becomes a problem if you want to
study which moves but you all know if you want to make a picture from something which moves you have to decrease the shutter speed so for running costs for example it's sufficient to have had a speed of 1 millisecond but if you want to watch a bullet smashing metal and you have to use like 1 thousand frames per 2nd more and finally if you want to go to chemical reactions the shutter speed is orders beyond that and you may have seen how such a movies made so you need be clams in order to get enough light hitting your object in the very short amount of time where the shutter is open right so the figure of merit for a normal lamb assuming synoptic luminous intensity which is defined as the photons per time per solid angle so basically the amount of light which are directed to your target but we want to make X-ray diffraction images so we need coherent light in our Figure of Merit looks a bit difference is called the brilliance of a light source and what we want is basically we want a lot of photons per time we want them emitted in a small spot size with a small angular there were regions and basically only 1 wavelength OK so this is the brilliance this is also key but before I want to show you what it takes for the brilliance to get from here to here I want to sensitize you a bit more about the scales of what we are talking so this is an example of some
objects which are as a sorted according to their length on a logarithmic scale so we start with a fingertip of some centimeters over a human hair down to molecules and atoms and we are able to produce plenty technology basically on the whole scale so we can produce a microbe year was that the diameter of some micrometre and even nanotubes stand although this is rather something academic yet but in principle we are able to arrange matter on an atomic scale yeah the corresponding
time the plot in time-domain could look something like this so we start with an eye blink of a couple of hundred microseconds down over the time it takes a shock wave to propagate by 1 atom in the crystal finally to chemical reactions or the ball period and it takes a one-gigahertz CPU about 1 nanoseconds to come make 1 computational step and optical networks which is or even a bit faster but basically we are not really able to produce technology and that time scale and and we are able to produce a laser powers in the was of light which is as short as 1 and the 2nd which is really amazing but keep in mind the diffraction limit so with this we can watch macroscopic objects like for example the micro and can watch the microglia within 1 defender 2nd and see how it changes but macroscopic objects don't change with an sample seconds things which change Santa seconds of proteins or molecules and we are literally blind at these objects within the lecture natural timescale and to give you a better feeling of the scaling here the fingertip is to an atom uh uh is about 2 times 2 times 10 to the 8 times bigger than an atom OK and that's about the scaling of the walking
distance from here to Tel Aviv to a fingertip and time-domain and link is to a chemical reaction like 1 year is to an idling and now keep in mind when you go to a hospital and you want to make an X image with a modern X-ray to from a thing you have to stand still for that's a 2nd right and if you want to scale that to an atom and to such a time scale and you immediately see that x-ray tubes are nowhere near what is needed for resolving proteins from the natural timescale
and I want to relate the re uh the development of all brilliance was something you knew so you know so this the computers speed and you all know Moore's law and you have kind of a feeling what it means to figure of merit increases in 12 orders of magnitude and 60 kids but the trade brilliance increased by 18 orders of magnitude and 5 decades and it was not possible by small innovations but uh very different steps so we have different generations of synchrotron light sources uh and finally the 4th generation we call x-ray free electron lasers in this talk I will go through the steps what it takes to build these machines but before I can tell you how we can build such a particle accelerator I have to tell you why these particles spectrally radiate and for doing that I have to tell you something about relativity
maybe you have been etched on his talk yesterday I would try to summarize it on 1 side if so we call our machines particle accelerators but I guess you intuitive understanding of acceleration is an increase of velocity but that's not really the case that a step by step so maybe you are familiar with Newton's law of kinematics telling you that the kinetic energy is 1 over 2 times the mass of the particle times the velocity squared but as Einstein reviewed the speed of light is a constant which can't be exceeded by any particle with a finite mass so it turned out that Newton's law of mechanics is only a borderline case for very low velocities find stands more general equation of kinematics and in here you have this letter to this effect a gamma gamma as 1 over the square of this square root and it basically relates the energy of a particle with stressed mask and it's quite an important parameter for us and it will pop up a couple of times in this talk so let me give you an example let's assume that we accelerate an electron and the proton with 5 million walls case of 5 megawatts and then the kinetic energy of both particles is 5 million electron volts the rest mass for an electron is about 500 K the Q electron was what it is about 2 thousand times more for proton and this means you can now plot the numbers in that the gamma factor is about 10 4 electrons well it is about 1 4 products the and if you calculate the speed now from this you will see that the electrons while being accelerated with 5 million walls travel was 99 . 5 % of the speed of light by protons only travel a 10 % so electrons and protons or in general light and heavy particles very different relation between the energy and the velocity In all cases and synchrotron light sources we always interested in a very high gamma so it's obvious that we only using electrons so the next step is applied to the radiator and this is an electron and the upshot of the electric field lines and you may be familiar with in relativistic effect called length contraction Lorentz contraction very need example is the ruler which travels close to the speed of light and it gets compressed with respect to an observer and rest in if we apply this length contraction uh to the electric field lines you will see that when the speed of the particle is increase the electric field lines are compressed into a very narrow cone perpendicular to the speed of the particle thank and now consider you want to change the velocity from here to here so you accelerate the particle and the electric field configuration has to change from that set up to this 1 but this can not happen infinitely fast but only with the speed of light so you have a time-varying electric field and this is basically radiation maybe you become a bit more
clear on this slide uh I make this simulation you can download the simulator of from this and is again a point charge in a directed now with the mouse and increase its velocity and you can see as I increase the velocity the field lines are compressed into this in a very narrow cone the and the radiation pattern gets more obvious if I change the direction of motion for example where running get on a circle and if you think just sit here and watch the electron you will get hit by a narrow flashes of electromagnetic radiation but and this is basically a synchrotron light source but I would like to look a bit more detail the on the uh radiation properties so here again this is
our electron and I calculate that the radiation pattern for this motion and I plotted the angular distribution here with the surface plot so you see that most of the radiation is directed in the forward direction and the opening angle here of this radiation cone scales with 1 over gamma and the overall power which is submitted scales with gum much the fall of the mice directly proportional to the energy so if we have a very high energy um basically all the radiation is emitted into a very narrow cone and forward direction and all cases come i something like 10 thousand so it's really small and a nice property of this radiation is that it covers a relatively wide range in frequency domain and you can easily it by changing the gamma or the energy of the particle and this kind of radiation was 1st observed in a particle accelerator called synchrotron and that's why we call this synchrotron radiation so coming back
to the picture of synchrotron radiation is very suited to study small things like proteins or molecules now the question is how can we put this into technology so how can we make use of it and of course you know it's particle
accelerators so what are the principles of the light source with 1st of all we have to generate all electrons so we need a device which uh serves as the electron source then we need something to increase the energy and finally we need a device to make them ready at both this radiation we can then perform all x-ray experiments it's as simple as that and I saw him too ambitious analogies to think of such a light source as a radio stations that also you have your input signal and you have a high po amplification and then you put this hypo signal through the wires which is designed to produce electromagnetic radiation of which only a tiny fraction it's a receiver case in the following i want to go through these uh different devices starting with the acceleration you may know
that if I connect a capacitor with the DC wanted source look at an electric field between the plates and if I place a negatively charged electron in here it will get accelerated right and we have this kind of
accelerators we call them funded of accelerators and modern ones like this 1 is up to 10 meters long and reach uh or can accelerate the particles by 6 million votes which is not there but the problem is we can't really put them in serious and we can't increase the water chief of because we would simply get a discharge between the 2 plates so the problem with this technology is it doesn't scale so what we do is we replace or capacitor with an empty metallic resonator called cavity and the connectors cavity you with a wave guide to an AC voltage source and this water sources operated usually in the radio frequency domain so some gigahertz that's what we call this already and the nice thing about such a resonator is that a relatively small are a field will start to resonate inside so we will get a relatively high oscillating electric field and we can easily put these in serious and if you put the face of a set up the face relation between adjacent cells correctly will get an alternating oscillating electric field and the really cool thing is now that we can put holes in here without really changing the geometry and now the cells are coupled so we can remove all the polar sources except of 1 and if you put the beam pipe in here Malik from there and free synchronize everything correctly you will see that we get an acceleration in each cell of the cavity and and of course I mean the devil is in the details but this is the basic principle of an RF cavity and and there was no growth in the theft and basically every particle accelerator service operated of these kind of devices
but just to give you 1 example this is a tesla cavity we have in our linear accelerators at the z here we have these 9 cells and it's a superconducting technology so everything has to be assembled in the clean room which is very challenging and then we put 8 of them into 1 of these prior Wessels with a lot of support and we plotted in these yellow things here put it down in the tunnel then we cooler down with liquid helium to to calvin and in these cavities we can reach something like 30 million words within 1 meter so this is 50 times more what you can get a phonograph accelerator and think of this 30 million walls between these 2 hands so to me this is really an impressive technology
the seriously and OK so the next step is the electron
source this a movie made from the foot the contest sentiments widen but the electron source fear that the easier on the basically the same so you see it's a very complicated devices and their whole laboratories only building these electron sources but this movie shows basic principles so in the inside you have a copper cavity which with its connection to the waste guide and from the inside the camp the you have a photo cassettes sitting here and this photo catheters impinged by UV laser pulse and by the UV laser hits this fall because there are 4 electrons emitted due to the full effect so each of these red of things that are about 1 million or 10 million electrons and we call this an electron bunch and then again we have 2 cells over RF cavity and everything is synchronized in a way that accelerates the electrons immediately as they are generated it
OK finally we needed a wise to make them ready at and I already told you we just have to them around the circle right and we can do this
most easily in dipole magnets you may know from high school physics or whatever the left-hand rule if we have an electron was speedy and the magnetic field perpendicular to it will get the Lorentz force in the 3rd direction so the whole thing is around the rate of the circle so now we have F everything together
to build or storage ring different electron source we need an forest cavity and then of the dipole magnet so the particle will move from the circle and continuously emit synchrotron radiation and is not that easy because we have energy conservation and why the particle in its power it will lose kinetic energy so it will finally spiral in and get lost so we have to replace that and in uh insert straight sections will be can place RF cavity to compensate for the power loss in the dipole magnets and then we have to put some focusing elements and here we use the quadrupole magnets to stabilize the system and this particle accelerators called uh synchrotron and originally this kind of devices were built for high energy physics applications like for example LHC you the large sovereign collide and so on is nothing more with this course but the basic principle I guess synchrotron and this could be oxaloacetate OK in the uh in the early fifties when they started to build this kind of accelerators the synchrotron radiation was found to be nothing more but a nuisance which make everything more complicated but in the sixties there's an X-ray diffraction became a thing and scientists started to realize about the capabilities of this radiation so that play some way optics In here which guided the synchrotron radiation to the experiments and these kind of devices are considered as the 1st generation synchrotron light sources and as an
example of this is that handles 1 accelerator in the late sixties here's accelerator so this is the RF cavity and there are some dipole magnets you see it's a fairly small devices very soon scientists started to want to have more power in their
radiation so in a bending magnet each electron ready it's so the intensity or the brilliance scales with the number of electrons right double the electrons travel the power and starting from that if you want to increase support the 1st obvious step is to put more dipole magnets and so this is an is
insertion device called we and it's basically nothing else but a serious of dipole magnets with alternating polarity so the electrons will move on a slalom trajectory in each curve you will get synchrotron radiation as from a single dipole magnet and by doing that you will increase the brilliance by a factor of the number of magnets but so nothing wrong with that then the next generation of the next step towards of brighter synchrotron light sources was the invention of an undulator and undulators very similar devices that of because the only difference is that now the bending radius is so small that the sum that radiation cone basically always points in the direction of the experiment and the mathematical details of this radiation is a bit are a bit complicated but the idea is that now you have interference of the light emitted in each of these curves and by doing this you compress the all-pole here from a we into very narrow spikes in frequency domain and this is great because remember we want to make X-ray diffraction images so we need coherent light so we need only 1 wavelength anyway so we put the filter in some if you place a few days and at the at that frequency will gain a huge amount of brilliance and and these kind of devices
are considered as 3rd generation synchrotrons so facilities which are dedicatedly built to produce as much synchrotron radiation as possible with many beamlines and many experiments the the
and as you can see here there are plenty of them operated in the industrialized countries around the world right now and as an example I want to show you that it of 3 accelerator we have it easy in Hamburg but need drink something OK so this is a
busy compass and here this ring is a tough 3 it has a circumference of about 2 . 3 kilometers so it's a fairly large devices including this 300 meter long experimental all of which a schematic sketch you can see here and each of these lines is an X ray beamlines with dedicated experiments from the inside it looks like this so you can't really see the accelerator because everything has to be shielded with these concrete walls because of the radiation but the accelerators here on the inner ring this is a picture from the inside and you you have the beam lines of the experimental chambers at the end K as I said this is a picture from the inside so these are the apocryphal magnets and we have some steering magnets and the other devices here these are the and the latest which produce the radiation and beamline at these facilities very expensive so most of the beam lines have to be bottom-most for example and this 1 year we have a robot arm which takes a crystal samples of the you here and then mounted on the sample holder and the curacy he is very impressive and we have the x-ray crisper sample crystals as small as 100 nanometer and then they are rotated around Texas inside a photon beam which is as small as 100 nanometer as well but why do we need crystals at all and the reason for this is that the cross-section between or rays and matter is very low so statistically we need 1 million atoms in a role to get 1 single defracted photo and you can imagine we need much more than 1 single photon to get the image on our detector which we can calculate something from so what we do shift increased amount of photons but this is limited by some constraints of all particle accelerators so we have to increase the amount of atoms in our sample we do this by growing growing crystals so this is a protein and we have to find proteins which we can form units of and then roll a crystal so we need many of these and then we can put the crystal in our life in our x-ray beam and at some diffraction spots and widening turning the crystal
around its axis we get of 3 D diffraction pattern and from this we can then calculate the 3 D electron density map of all sample and if we know the debt electron density map we know the structure you can see on the cumulative number of structures which are wearable and the protein database and you can see that within the last 20 years there's been an astonishing increase most importantly made possible by X-ray diffraction images in these modern third-generation synchrotron light sources and right now we are not only able to make pictures of small of proteins like them I will be in but even very big ones like the ribosome but this is not really by far not trivial so for example the ribosome the 1st X-ray diffraction pattern of ribosome was made in ninety eighty but it took 20 years to calculate the structure from this and although this number here seems very high today in less than 2 % of the human protein known as known so 8 89 98 per cent of the proteins of all body are unknown and the reason for this the bottleneck is the crystal growth so it's very hard to get uh most of the proteins to form the crystal some of them are even much it's just not possible to crystallize them at all for example membrane proteins but others it's very difficult to grow large crystal so what we ideally want is to make be able to make a picture from a very small crystal even a single molecule but in order to do that we have to increase the amount of photons by something like 100 million this is really not easy but let's consider for now that we would be able to make a storage ring bright enough so 100 million times brighter than it is and 1 uh to make and the diffraction image of a single laser so I'm what would happen of this this is
uh a simulation published a couple of years ago and what you see is the cool explosion of lies so as the x-ray beam hits the it's a sample it immediately blows away all the electrons in the molecule and what is left of the positively charged nuclei which repel each other so the whole molecule goes apart and the problem is no that because of fundamental particle beam dynamics it's not possible to make an x-ray storage-ring policy smaller are shorter than the about because 2nd so even if he would be able to make a solitary impulse bright enough to watch a single molecule we would just be able to see a very picture of an explosion and this is where free-electron-laser came into play because in the linear accelerator it is fundamentally impossible to produce an X-ray pulses as short as some kind of 2nd but as I told you we have to put 100 million times more photons in that's smaller short parts so this is not easy what we do
as well 1st of all let me rescale this picture we replace we replace uh the and later by a very
long undulator and by doing and now comes the point because if we set up everything correctly will get on top of this radiation pattern from a long under later we'll get narrow spikes of coherent radiation and this is what makes a free electron laser so important so mathematically the radiation scales now with the number of electrons squared and the number of electrons in all branches of something like 100 million or a billion so this is really a huge number but it's ever look inside what's happening in the undulator so this systematic conventional the red circles are supposed to be electrons and a whole bunch moves in the end of it OK and there exists a resonance conditions between the undulator period and the period of the emitted light so here here's the and the later period of the of the emitted light today relativistic gamma factor and this K value which corporate some information about the magnetic field that's important for now so I'm only looking at the wavelength of the emitted light which satisfies this condition that the now let's have a look so this is the electromagnetic wave which is emitted by that electron and the whole bunch is moving up and down in the picture so some of the electrons move in the direction of the electric field house sorry this is the electric field lines which are plotted here so some of the electrons move in the direction of the electric field was some of them move in the opposite direction so some of them will gain transverse momentum while others will use it and if we had this resonance condition both the direction of the motion of the electrons and the electromagnetic waves the flip sign at the same time so this process repeats itself and while all of this is happening we are in a magnetic chicane meaning that there exists 6 dispersion and dispersion means that the bending radius depends on the energy so if you have a large energy and the bending radius speaker if you have a small energy of the bending radius is smaller so some of these particles have larger transverse momentum so larger transverse energy so to say and they will move uh they will fall back and others will overtake the bunch so we have a self-ordering effect which repeats itself now coming back to the big picture so from it at the beginning we start with the
incoherent radiation so all the electrons by their movement of where they're bend around the circle uh radiate but there's no fixed this relation between them OK so this is incoherent radiation and the intensity of that of such kind of radiation scales with the number of images in this kind of of and this uh example of number of electrons and now for Esteban shmoo flute fooled the undulator the self-ordering effect uh leads to a micro munching on exactly that length scale of that radiation so for the wavelength of satisfying this condition we will get a coherent radiation and coherent radiation scales with the number of electrons squared it's not easy to get
from co incoherent to coherent radiation especially if you want to have someone to have rays here sorry so what we need is a small beam of this is just to give you an idea of the order so don't take these will to serious can be affected to a free between them but we need a small beam something like 10 micrometre entrance were size we have to have it as short as 10 my computer and we have to get it on the high energy something like 10 billion electron volts and we need a very long on the later some hundreds meters and within that and undeleted undulator we have to align the electrons to better than 10 micrometre in order to have an overlap between the electrons and their with uh and the light so this is really challenging this is a sketch of such a free electron laser so usually we have different acceleration stages and in between we have magnetic she chains we call them bunch compressors and in them we are able to produce a very short punches and we have a long undulator and finally we dump the electrons now light gets to all experiments as
you can see here there are just no 5 of them in operation and uh at least 5 of them operating in the hot X-ray regime and Anderson as example I would like to show you the European accessory which is
the largest free electron laser we have emerged of this is a map from Hamburg you can see with it's all a length of about 3 kilometres agreed to sell at the daisy compass and reaches the adjacent federal state of physical extend where the experiments uh the experimental hall this field we can't see much from above because everything is is beneath the earth they would
like to show you that movie which was made which was made why the accelerator was still under construction so right now it would not be possible to to walk down there would just die but that it was possible same and it was really impressive to be on their hands see all this I take next to you and it just never stops but anyway you can see this is now the main accelerator it goes on for another kilometer you see where we are and this goes on for 2 minutes I think it's a bit boring and you can watch this movie if you want at home I think I double the speed anyway but I want to give you
some numbers so in average should we we take about 9 . 5 megawatts from the great this is about the energy consumption of a small city and from
that due to the utilization of the superconducting RF technology we are able to put 10 % into all been so we have an average Pollock over 900 kilowatts which is really impressive for linear accelerator From this we get 0 . 1 per cent in 2 0 X-ray beam but finally only less than 1 % hitting uh or get in the diffraction spots so you could argue that the overall efficiency of this machine is terrible have and I would agree and also 900 watts of X-ray beam policy and is not very impressive but what makes this machine worth a billion EUR is its ability to compress that power into very narrow spikes so what is interesting is the
people In average we have the repetition rate of 27 keywords so 27 thousand proper X-ray pulses per 2nd are produced with a wavelength of about 0 . 5 angstrom has energy of 1 individual and a pulse duration down to 3 cents 2nd and this is the time it takes light to travel 1 micrometre this is a really short and that we can focus this X-ray beam down to a very narrow sport and in this part in the focus point with a power density of about 10 to 17 watts per square centimeter I guess you don't know what went into the 17 watts per square centimeter is but we give you an example is about the power density is if you if you would take the total sunlight hitting the earth on 1 square centimeter so this is really intense and you have to be careful because if you accidentally hit something I I another thing I would
like to show you this uh that it's really not easy to boot or to operate such a machine I just for the European we have 9 million control system variables there's a picture made from the control room at easy you see that there are a lot of screens and you have access to all of them so it's really not easy to design a control system which can be operated by many people and give you access to all of these are made an animation on screen recording because once I had a measurement shifted flesh which is another electron of free electron laser we have it the easy and I had to dig out the toroid signal which was not from the top layer of the controlled system it took me quite some time to find it so this is the this is the of the top panel of the control system and as you can see as you
press some of the Spartans that will open up a panel with a lot of other other buttons and if you press 1 of these buttons another panel
opens and please OK and please note this and over here and here but finally thank you so we we need a lot of experts working together because no 1 is able to keep all of that in mind I another interesting
number I find is that data production rate so now I'm not talking about the machine and just talking about the X-ray detector ok and there we have about 1 megapixel with a resolution of 16 bits and we want to record this twenties 7 thousand times per 2nd and this means we're 60 gigabytes per 2nd just to give you a number of the LHC after filtering has about 600 megabytes per 2nd so you can imagine that we also need very sophisticated trigger levels in order to deal with this amount of data because no 1 is able to record all manage 60 gigabytes per 2nd and as an example this is uh the amount of stored data in the 1st weeks of operation of the European here so you see we are hundreds of terabytes and keep in mind within that period the machine was working with less than 10 % of its full capacity so we're talking about petabytes here so this is also not that easy to control the but finally I would like to close this
talk with the UniDic occasion which you can only do 1 these free electron lasers and it's about molecular movies so for example this uh um Byron complex in acetonitrile solution if you hit it with the UV laser or UV light in general than it will perform a chemical reaction and lead to an as it legend and the bending of such a solvent molecules and chemistry we know this for many decades but the problem is that basically all of our knowledge of chemistry is it true to that through the librium science so we know the reactants and we know the K. A. reaction products but we don't know what's happening in between and usually there's not only 1 reaction path but there are many with different probabilities you can imagine if we don't know anything in between it's very hard for us to design a drug or a catalyst or something something that this this is basically nothing more than than and applied science at committee and we just try and they're all so it would be would really benefit from knowing what's happening in between and with the x as here we can do
this and this is a picture of the experimental hall in chain offered here we have these 5 beamlines now we're watching 1 of them so here can come out of X-ray beams this a photon diagnostic section we can analyze the properties of 0 X-ray beams and here finally we have the target this is at the liquid jet target and it's not easy to allow tool design because we want a single molecule to get hit by or
X-ray beam we don't want to have to and we don't want a 0 and all of this has to happen in
vacuum and it's really not trivial to build these kind of experimental chambers OK now how can we get to a molecule a movie from this 1st of all we have to be able to trigger our reaction and we can do this with the UV laser pulse is so we had our all molecules the relays and the reaction starts and then we can make a snapshot with 0 X-ray laser and by setting up the delay time between the UV and X-ray laser we can't make a snapshot from different stages of this reaction and that's basically everything but also the readout of this detector is very sophisticated so between the different layers because between each pulse there's only 2 100 nanoseconds and then the defector has to be ready for the next picture so it's really not trivial to build these and this is basically the most powerful X-ray detector we have on earth but finally we get all our images and from each image we can calculate of the fish the structure of all molecule and the putting them all together we are able to make the molecule movie from a chemical reaction you see what it takes to make something like this and you guessed I guess you you understand that it's a long way to get
to something like this but in principle thing and food you but only a week you are able to resolve the structures of these proteins but also there's whole free electron lasers may enable us in a couple of years maybe the kids to watch these kind of movies but mothers just used but there's no real experimental data so thank you very
much and if the prefix thank gruesome was mn think your emerge for his use occasional if anything goes wrong with your post AUC in Berkeley I recommend you go to science communication and future we already have a question from the Honourable heard and I yeah there's actually 1 question from going Ken how will do the experiments that the kid to I have seen the talk yesterday as well and I think uh you mean in general the x-ray experiments or from the European Exascale on from the internet but by OK if I mean I would say they replicate quite well there are experiments made at different X-ray sources and from time to time they tried to cross check and other X-ray sources or tried to some make the experiment a bit different and I think this is kind of replicating it but I'm not a photon of an expert so I don't know they II to the machine I don't really care about the so I'm sorry OK murderer for 1 please and OK again in the really amazing tho and will submit that there was the current status of the X so because he showed lot the injustice this procedure how we went to women we how far are we actually do that for a simple example something like you Mary and indeed depends for what I didn't tell you how difficult it is to make a home many pictures you have to to combine to make such a more useful just as it combines several hundred of thousands of X-ray images uh or diffraction images to make such movie so we need a lot of but of be time and follow especially right now I think it's more difficult to prepare the samples and and and to get to full capacity because of some issues of the accelerator I would get something like 1 year To date to something some general the machine is ready and operational and that operates on all the in that they just not that all subsystems are working you know like some of the some of the experimenter chambers on a ready on some been properties can't be it right now talking microphone number for at least look at some of the holiest of molecules degrading by uh but that of the free electron laser sorry again she's so is shown before and you don't have a crystal molecules of the 2 great since the and how do we stop of the free electron laser you mean how do we stop the molecule from exploding based on we don't think of it as it gets obliterated in each other so that's why we have to make a 100 thousand pictures because after each maybe let
me show you this may so it so each chart being this is all molecule and gets hit by this laser in each other gets destroyed and it's more difficult because the orientation of the sample is a random and each shot right so we need very sophisticated software to calculate this week effect image from this the finally resolve the structure is much more difficult than if you have a
crystal because they you know your orientation you can rotate it in a defined way but finally each shot is that we need to get the data from 1 child that for the microphone number 1 least those with more of technicalities there and How will always be a cause of the electron
beam dump and whether using for the electron beam dump who 0 you get the amount of light and start only committed to in the event of that you don't destroy everything that that's yeah that's basically the limitation of this line and kilowatts is a specification what we get on the kinds of things that are not authorized institutions and use the
blocks of uh what is a graphene I think and kind of rotating magnets to a to a such that the beam doesn't it the same spot every time and but it's basically just a big big block very long like hormones that may be 8 meters like this big and then we have several of them which can be changed and then they have to put
away for some decays conclusion on but it is always you and thank microphone for at least the 1st thank you again for this really amazing talk this is a very greedy question but is it
it is anticipated that the growth in the ability of these will continue to go beyond what free free-electron lasers have achieved and is there a glimpse into what the 5th generation of synchrotrons would be you know I asked a couple of guys uh and the scope of preparing this talk and depending on where they are they aren't so different things so some of
them answer no uh it will be different techniques so free electron lasers have the unique ability to make very short pulses and this may be becomes even better so less than one-tenth of a 2nd but there are other tools like electron diffraction or uh also electron-microscopy which are maybe suited better for different samples but I actually I don't know what's really
going to be the next step in synchrotron radiation sources thank you organ let's be fair to the internet concerning questions and yeah we have some more questions about you is it the right pattern sheepish asking how long does it take to run an experiment as in writing this back the experiments sending the beam connecting the images imprinted gene
is producing the ship uh being time is something like that so on flesh are other free electron laser the to typical beam time slot is 8 hours and so the machine runs 24 7 but some experiments take 8 from 16 Some 2 days but that's the order so that the can almost and setting up the experiment is
actually the bottleneck so you this can take up to 1 week so I don't unfortunately I don't have a picture from the experiment experimental at 1st but we have different beamlines and and there were 10 people working there to build up the experiment for 1 week and then they have like 8 was of X-ray beam and then they work half a year on
on reading the data and code and combining these images so the beam time they're making the images as the smallest part we're microphone 1 please in the interval the great talk a lot on my question is I'm sure you are and they're of some these that protein folding software projects which try to make these
images by calculation how well do these work and how much do you benefit from these approaches can mean that's a point we don't know how well they work I mean we have the simulations we can find the 1 you chew and there are nice but thank you thank you or right another microphone 1 please yeah and
this was an amazing talk from canada related but more about how the focus of the X ray paths yes but I don't know if I can answer your question I I I should tell you what it had a thing for given this is you discussions I think that this is probably outside so
Internet ask questions been restricted to
these would like to know if you could tell you some more details about how the X-ray camera manages to hold so many data digits edges so the period of time uh OK to the Internet question no I can't really by uh I wanted to ask the guy who designed the detector or what's the responsible for the the designing the detector what he was an holiday already in the last week before christmas so I couldn't really uh uh get an answer to this question I don't know it exactly I just know that there are several layers and uh it's not so I would call should I think that the biggest very soon they wanted to write uh pick a comprehensive uh some comprehensive stuff about the X-ray take on on the home page of the European exceptional so I would recommend you to look it up there but to come to your question we do this with basically diamonds or some some diamond-like crystals this is an x-ray and they're all we have and and therefore the amounts of grazing incidence angle so that's how we focus these these themes and very I find it was in the news of the flatness of this moral is really amazing but I don't I don't have the numbers right now but look it up it's crazier the the microphone 1 yet and this is of course an amazing piece of hardware but as you mentioned you short of control software it's also an amazing piece of software and mold of software and can give us some numbers on number of programs lines of code for many years what protocols and you spend a billion in our software also probably guilt this year's special on that would be an interesting number no I don't have the number of lines involved in this college I know that the amount of computer uh of uh of the CPU power we need is not that much so it's it's more the most difficult thing is to get all these channels appear on all control systems for the graphical uh the graphical interfaces is more challenging than a then the could work with the data that I really don't know how many people know I can't really tell you this but if you write me at the end of this slide I have my e-mail address I I could ask some to realize that easy became microphone to please I also have a question about the control software you have a query language defines the controls instead of having to step through all those windows about yes of course of course but usually when you when you have no clue of what you're looking at them sometimes easier if you have a we where you can where weights of the sort of but of course they can control you can have excess read and right also by applying by just writing lines you know Internet questions no more questions OK microphone 1 this is the idea that from my question as a standard policy in place around for like publishing stuff like only of nexus of something and a decent and everything to come and reversal of the length of time do I have some policy to fulfill told only idea to publish I mean you have to publish in and mn is an open access that the question that's a good point I think it doesn't have to be not so you have to make sure that your results are published and but since it's not to so In a good point I know that it is a private company can also come and ask for the time but they have to pay a lot of money to get that but if you are a scientific researcher or university or you get it for free the thanks the thank
what tution fees
on you thank you thank you and my if you do that it can't compare the people back
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Metadaten

Formale Metadaten

Titel Free Electron Lasers
Untertitel ...or why we need 17 billion Volts to make a picture.
Serientitel 34th Chaos Communication Congress
Autor Hellert, Thorsten
Lizenz CC-Namensnennung 4.0 International:
Sie dürfen das Werk bzw. den Inhalt zu jedem legalen Zweck nutzen, verändern und in unveränderter oder veränderter Form vervielfältigen, verbreiten und öffentlich zugänglich machen, sofern Sie den Namen des Autors/Rechteinhabers in der von ihm festgelegten Weise nennen.
DOI 10.5446/34952
Herausgeber Chaos Computer Club e.V.
Erscheinungsjahr 2017
Sprache Englisch

Inhaltliche Metadaten

Fachgebiet Informatik
Abstract Wouldn’t it be awesome to have a microscope which allows scientists to map atomic details of viruses, film chemical reactions, or study the processes in the interior of planets? Well, we’ve just built one in Hamburg. It’s not table-top, though: 1 billion Euro and a 3km long tunnel is needed for such a ‘free electron laser’, also called 4th generation synchrotron light source. I will talk about the basic physics and astonishing facts and figures of the operation and application of these types of particle accelerators.
Schlagwörter Science

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