 I like to show you what you need to operate a neutron imaging beam line and what kind of systems are needed. And as you see, neutron imaging dates quite some time back, as you have already seen yesterday as well. And what are we doing today? And a lot of things have happened and will happen in the future because the neutron imaging is actually done at Spillation Sources. And there are two, maybe three, I think the shinies have now one as well, the two dedicated imaging beam lines now at Spillation Sources. And that's ISIS in the UK and a J Park in Japan. And as I said, I think the shiny Spillation Source, they also have one or it's under construction. There will be another one in the US at SNS and then we will also have one at the ESS very soon in just a few years time. So it's an exciting time to be in this field. And so the outline is that I will go for some historic developments and give a more broader overview showing a generic instrument which we will follow along all the way from the neutron source up to the detectors at the end. And I will show a little bit what means time of flight versus steady state instruments. And time of flight is what comes inherently at the Spillation Source. You can of course also do time of flight at a reactor source as you will also see in this presentation. And then the neutron source will give you a specific neutron spectrum, which is very important when you want to do imaging with it because it gives you different contrast modalities if you have a more thermal spectrum or more cold spectrum. And then I will go through a couple of instrumentation things because this is where a lot of some magic happens, having better instrumentation enables better instruments and hence enables better science. So there's a neutron transport part, how do you efficiently transport neutrons from your source all the way to your sample and detector. And then can you shape the beam in certain ways, do a wavelength selection, have a good pinhole collimation, all the things that are important for imaging will cover some of that. And then a really vivid field, especially now this time of flight beam lines is neutron detectors. And that is changing very rapidly and will really enable new breakthroughs hopefully in the future. And then I will just go over some some example instruments so you should take this lecture, while there's maybe a lot of information in there. Just take it up and that you have seen all these topics and then you can go later, also back to the slides and and ask if you have questions. So I'd like to highlight that a lot of the things to compile this in this presentation I took from actually a school that was launched by the IAEA. Then there's International Society for Neutron Radiography so they teamed up and actually Nikolai Karilov and Ibar Lehmann have set up a course there so a lot of information actually comes from this website. And one interesting thing to look at is again looking at x-rays and neutrons and the neutrons since the discovery are always running a bit after the x-rays. And as we already discussed, the neutron was discovered in 1932 by Shetvik and first neutron images came came just a few years later. And what's striking here that neutron x-ray tomography was really already done in the 1970s in hospitals. And of course it has a big push because of all the medical implications. First neutron tomography was only done in 1995 so actually 25 years later. And what really made the difference however is that one could do digital imaging. You don't have to use film anymore and similar to your normal photography has really changed the world how we do how we do imaging in general. And the time of flight business started then really for imaging only after 2000 and ongoing now. And looking a little bit down on the numbers for x-rays and neutrons as I said 37 years after the x-rays was discovered the neutrons were then discovered. Neutron imaging started even only 50 years after x-rays and neutron diffraction comes also quite a bit after x-ray diffraction. And as I already said tomography 25 years and face contrast imaging actually comes knowledge. There's not such a big gap to do that with neutrons and x-rays. And nowadays when researchers want to use neutrons, it can be perceived as a really competitive and complimentary method to state of the art x-ray techniques. It's not really a bit little like it was maybe 15 years ago when neutron imaging could only get spatial resolutions of maybe 200 micrometre and was very slow. So a lot has happened really in the recent past. And if you look at a generic neutron instrument. So we have a source which can be a reactor or some spallation source for example. And then these neutrons need to be moderated that means they need to be slowed down to energies that can be used for our material characterization. And then after that somebody can use some filters and different apertures. And then the overall beam transport that can happen in neutron guides or also flytubes that I will show all the way up to your sample and eventually to the detector and behind that there's typically some beam dump or beam stop that people can walk safely, safely behind that. And of course the neutron source is a lot of safety requirements, access control, radiation control, dosimetry and all of these things. And you can imagine that's a lot of the things that we are currently dealing with at the ESS as well to make a safe place to work. And then comes a lot of beam shaping components or advanced components like an energy or wavelengths selection, you can polarize your neutron beam you could put grating interferometers there. So you can do a lot to your beams that you can do more with it in your experiment. And after all you collect all the data. And then you have some computers nowadays and software tools and so on. And this has become its own science at ESS actually have a data management at software center located in Copenhagen and instrument data scientist. That's a role that is coming up at more and more facilities now to deal with just the data that is acquired in such an experiment. And this is big chunks of data now and especially if you have a pulse neutron beam and everything timed. As you can imagine there's a lot of data coming in that needs to be handled stored and analyzed and so on. And I will follow this little sketch that you see on the top right now to go a little bit through some different instruments. And let's start with a neutron source. Neutron sources can be research reactors nuclear reactors can be spallation source as we already said. Not to forget that one can also have just some laboratory like radioactive nuclear sources or also other accelerator sources. I like to highlight what's really important when you do anything with neutrons is the difference in neutron energy. There's a huge variation of when you produce neutrons 15 orders of magnitude their high energy neutrons fast neutrons epithermal thermal neutrons now it becomes interesting to do diffractions catering and imaging and also called neutrons. This is what we are interested in. And after that comes even ultra cold neutrons. And this table here gives you just the reference. V and imaging typically actually talk in wavelengths rather than an energy that is at least how it's mostly done now. And the wavelength ranges is between let's say one angstrom and nine 10 angstroms. And that's an energy regime between one MVV and 100 MVV. So keep that a bit in your mind because many of I will show you some resources where you can look up neutron cross sections they're often having energies. And so you need to quickly convert back and forth. And then these are also in logarithmic scale so it's a bit different to watch it so you need to do the unit conversion to see it the way you want to see it. And also I like to highlight don't get confused when you read papers on web pages the definitions for these different energies they often vary in literature quite a bit. And it can get a bit confusing so these are not set in stone. And on this side I just like to highlight so these are the four different types of neutron reactions that are highlighted before. What's important to do if you want to do imaging you need a lot of flux. And also we said we want cold and thermal neutrons and cold neutrons really I mean nuclear reactors installation sources these are the two main sources of choice of course they also come at the highest cost. And again you have already seen this I believe many times now we can produce neutrons by either fission in a nuclear reactor or by spallation. And at spallation the time of flight concept is is very inherent. And to start out with the maybe some history again is. This is one of the first nuclear reactors that you see on this image is a graphite reactor, at least the first one that was built for continuous operation it's an external graphite reactor and how rich. It was one of the Manhattan project, and it was one of the first ones to be used for new transcatering experiments. And it turns out that this even led to a Nobel Prize. So to maybe have a short pop up course here I wonder if anyone of you know who these two gentlemen are there, who have a relaxed way of working with a pipe and everything who won the 1994 Nobel Prize for the development of new transcatering. Do you know the names, actually anybody's still there and do you hear me as a sanity check. Yes. I can. That's a good sanity sake. So these two gentlemen were willing and shall. And they won the Nobel Prize for for their work they carried out back then. And on to the next slide so after this reactor nowadays there are over 200 research reactors worldwide. And this is a nice overview again by the IAEA, how many of these do what type of things a lot of research research they do isotope production for medical isotopes and so on. And many of them are doing also neutron scattering and imaging, and actually more of these facilities claim to do neutron imaging than neutron scattering, which is a bit opposed to what the big large scale facilities are actually doing their more scattering instruments and imaging instruments. And the main reason is probably that if you want to do basic neutron imaging it's very simple to do. And what you really need is a detect time principle and you can already claim that you do imaging that's also I think probably it says why it claims to do imaging. If you want to do really very class Newton imaging, you need of course a very powerful source of neutrons and again can be by fission or spallation. And there are many of these beam lines operational worldwide so I name a subset of them on this list. And this is a steady state of reactor sources. And then there are also spallation sources with inherent advantages that you can do time of flight. And then there are a couple of special specialties let's say, and these are beam lines for example at pulse reactors like in dogma in Russia, or continuous pulse source like it is at PSI in Switzerland. And in addition to that I like to highlight that many of the small reactor sources actually closed down in the recent past. As you had from Nikolai, the wrecked and Berlin closed down another one in France LLB and also there was one in Norway, and actually also did imaging there. So these are closed down so we as a community need to ensure that there is enough facilities for people to do their research in this field. And there's new facilities planned as well. And this is a little fun slide that I like to include here to show now this is actually when you have a large scale facility that imaging is only one of many techniques offered there. So there's triple axis spectrometers, shopper spectrometers, powder diffraction and so on. But in the recent years there are now so many imaging techniques that one could actually have all the different imaging techniques would already justify a neutron source just to do that. But since this has at least not yet facilitated may change with other type of neutron sources that may come in in the next decades. Imaging beam lines need to be very multiverse instruments to cover a lot of these different imaging techniques about which you will learn this week. And another slide now showing the evolution of neutron sources over time. And what you see here is the neutron flux, how it developed over the different years. And you can see also reactor sources and then accelerate meaning the spallation sources here and ESS will be the most powerful one to date. And it's the US SNSA also planning a second target station. So the sources are getting better and better and everyone is learning from each other. And actually the stuff building these sources also quite actively collaborating and also working and exchanging personal from these facilities to make them so good. And so this is just a view in a reactor. I don't want to go into reactor physics here really, but you have fuel rods and control rods. For our imaging application what is important that there is a moderator that slows the neutrons down to energies that are actually then useful for scattering and imaging. And you will also see very often the term cold source, which is a special moderator to slow down neutrons to the cold spectrum. And then the typically the beam from there is transported in neutron guides to not lose any neutrons along the way. And another, the other type of source as you know is the spallation source, where a high energy proton beam is smashed into heavy nucleus and thereby producing free neutrons. What's important to note is that the operating pulse sources or spallation sources now actually short pulse sources so they're creating a rather short neutron pulse that gives a fairly good wavelength and energy resolution. And then you integrate it over time so it comes at a certain frequency when you sum it up over time and compare to that of the more most powerful reactors, the integrated flux is actually a lot lower than that. But because it's a pulse source one can don't have to throw away any neutrons to do wavelength selection like you do at a reactor, you can use all of the neutrons, if you're interested in the wavelength property of that. You can already see from that that reactor sources and spallation sources are also especially for imaging applications very highly complimentary to each other. So you cannot really say that one is better than the other, but you have to think about your science case and this will also be important when you think about your proposal writing exercise. What is it what what you want. And maybe on this slide I can briefly already mentioned that is actually not be a short pulse but a long pulsed neutron source, giving the advantage, basically combining the best of both worlds that the average flux actually is is that of the highest of the most powerful reactors, but it comes in a pulse shape. When the energy wavelength resolution is not as good as of a short pulse source but then we can use shoppers to make the piles again short, and you have a lot of flexibility and that's philosophy behind the ESS. I don't want to go into the detail here either but they are of course some special cases like every time in life, nothing is only gray and white. SYNQ at the PSI is actually a continuous palatial source, and then actually in Russia, they couldn't resist actually operating a pulse reactor source where they have a flying reactor basically. So there are some extensions so don't I mentioned that you don't get confused when you hear the different terminologies. And for you to see a spallation target, this is the one of the SNS in the US and Oak Ridge. It's a liquid mercury target. And that's how it looks like and they use liquid mercury that's pumped around to deal with the heat load when the proton beam hits this target. So what it looks within the core vessel here the moderators then around the target and the proton beam is actually hitting from the bottom right of the image into the target. And this is actually how our target will look like the ESS the concept is similar but yet different, because we will be using not a liquid target but a solid tungsten wheel. And that rotates around to deal with the heat load. And to give you an idea this the moderators that you can see on the bottom right side that's called the pancake moderator because of its shape. This was optimized for at least a decade to come up with a very best performance of this and was changed several times with extensive computer simulations. So all the neutrons that the ESS will come from. And then this is how the facility will look like at ESS. The target is in the center that you can make out there and the moderator and then the new instruments around it. And the imaging dedicated imaging beam line Odin will be located here 60 meters away from this target. And also some other beam lines will also do imaging and combine it with other modalities like the engineering diffractometer be able to put an imaging detector in and also powder diffractometer Heimdall that you see there. And many others like imaging is becoming now more and more of interest to the other instruments to have imaging as an additional option because of their space why not put an imaging detector there. And with that I like to go over now to look a little bit in the differences when you have a time of flight versus a steady state neutron imaging instrument. And what are the main differences between time of flight and steady state but time at steady state it scattering instruments typically they want to use a single wavelength. And if you want to cover diffraction range and you need to change the angles in imaging we don't do that. So we only have one angle we have to detect a behind. If you want to change the wavelength then there needs to be a tunable monochromator that I believe maybe Nikola already mentioned otherwise you hear in this lecture and also in tomorrow's lectures. Or you use you don't do any wavelength selection for imaging but actually more typical. So instead of, I can find a pointer, which I maybe don't find now. Not sure if you see the most but you can get the light the, instead of the purple line of the spectrum that you can see an intensity versus lambda wavelengths, you're using actually all the spectrum what it's called the white beam imaging. And in time of flight now, you use all the wavelength readily so on a diffractometer it means that you don't have to change your detector angle anymore, which we do an imaging anyway not so it's an inherent advantage for imaging now, you can get the red, the baby blue and the dark blue wavelength all in the same shot. And this is the thing that I showed you already yesterday I just like to show you again, when you have a reactor, you're picking part of the spectrum. If you want to do monochromatic imaging if you don't use it, you can use a full white beam, of course, or you pick a single wavelength, either purple neutrons yellow neutrons or red neutrons. And at a time of flight so as you can, you're using the full spectrum basically in every shot and it comes in a pulsed way. I see some question now I can go into that in a second. And yeah, so these are the pulses. Let's see is a third or fourth generation neutron source that's a good question. If I have a set answer, I can give you my interpretation maybe. Yeah, I guess one can classify it as a fourth generation if you classify SNS or the others as the third one. I don't know if Steve wants to ship in, he has been in Lund before me. Yeah, I'm not sure. Yeah, I couldn't answer that one either. But since I'm representing ESS I would say firmly as the other fourth generation and the other ones. It's not the same terminology as with the synchrotrons, I think yet. It's a brand to like ESS is like different with its long pulse versus short pulse is a slightly different type of facility. But otherwise, I guess the technology is very similar. Yeah, that is true and you actually I mean in principle we can tune we can make the pulse a proton beam also short and turn ESS into a short pulse as well. It's more like it's like a hybrid you can think of the SS as being like sort of a hybrid. And when you talk about long and short pulses, how long are these pulses? Yeah, so for ESS, long pulse is about three milliseconds long. And then the others are like a few microseconds long and there's a slide where you will show these, where I will show now in a few slides a different pulse length so we will come to that. So determining the wavelength resolution you have already seen it and you will see it throughout the lectures, doing it at the reactor source where a wide beam is coming from your source. You use a monochromator to pick out a single wavelength. And what I want to highlight with this is basically normally you need some, if you want some wavelengths resolution, this is scaling if you want a high resolution you have a lower flux, a lower resolution scales to a higher flux. So they scale to each other and that's why ESS is interesting because you can have a low wavelength resolution and have a high flux where the short pulse neutron sources always give you inherently a high resolution but then not the highest possible flux. And this is a little bit the energy resolution that you can achieve with different types of monochromatization. So this time of flight with a short pulse you reach point two to three percent depending on the length of the instrument at ESS we will look at like 10% resolution to give you like a rough idea on the length of Odin. And then you use different ways of monochromatizing the beam. Like I say this is next shaper but you can depending on if you use a velocity selector monochromator or so you can also reach between 10% and and down to let's say 1%. Neutron spectrum. This is important because it's of the interaction of neutrons with matters you already have learned. And some instruments and all the instruments have a characteristic neutron spectrum depending how they are constructed. And this spectrum here is actually from the PSI in Switzerland where it's using the same source but two different neutron imaging Neutron and Icon and Neutron is a thermal one and icon a cold one. And this plot on the bottom left is an energy. This is the same plot now in wavelengths on the access as you can see here so make sure you're converting your units and the access rightly that's what I mentioned earlier. Because it looks quite different than you don't put in logarithmic scale and convert energy to wavelengths. And this is then the implication what it means when you want to use the neutrons for an experiment the middle plot is break edge spectra for materials that are footprint of the crystalline structure and you're interested in characterizing the shape of this edges that you see here from iron copper. For example, and you can see they occur towards a colder spectrum. So, you don't want to fool like Neutron wouldn't have actually any neutron flux left at this very big break edge that you can see in the center of the plot for example. At the same time, for the Nadium you can see as an example the longer the wavelength and the tuniation is getting larger. So again at the trade off and depending on your applications, you may want to use a different instrument. So this diagram graph is a plot on different scintillator materials that are used for detectors. And I think I will go over these slides now a bit quicker to show you in view of time already 30 minutes into to be able to show you a little bit more. This is actually however related to the question earlier about the length of the pulses. And this is a short pulse actually now. And it depends on the incident neutron energy on a short pulse how short the pulse actually is, but you can see the law, the largest one being 300 microseconds. And the smallest one maybe 2025 microseconds long and this is at the SNS at J Park. And at ESS as I said we have three milliseconds. So it's really a lot longer than than this. And what's important if you have ever done diffraction, where you get a diffractogram from your material, your diffraction peaks. Actually they do resemble the shape of your incident neutron beam spectrum so you won't get a nicely Gaussian peak. But your diffraction peaks will look like your incident neutron beam spectrum when you zoom into these peaks and that has some implications on how you fit such spectra for example. Whereas that ESS on the long pulse we use shoppers and then we create nice Gaussian shaped peaks again in a diffractogram. But this is a side note don't worry if you don't follow through with everything. Another question was regarding time of flight how can we take advantage when different wavelengths 40 CT scans. I would like to cover that tomorrow in more detail that question that's a very good one. And rather like lately emerging technology. It's a practical example for now whatever just using a different beam line, you're already doing by spectral imaging technically and it's already a wavelength selection because you have more thermal or more cold spectrum. When you look at this you see that the thermal neutrons can penetrate parts of your sample better, we're called neutrons can but the cold neutrons reveal more detail in many parts of this and this is sort of like you know from automatic fire extinguisher that you can see on the right and the left is a bullet. Coming now to neutron transport. You can transport the neutrons from the source to the sample to the detector. And one way to ensure that is to use a flight to because neutrons get also absorbed and scattered by air. So you put an evacuated flight to in between there. And, or you can put also some, some gases in there alternatively. And typically aluminum is the material of choice here. And you have to consider many aspects when you design your neutron instrument. And one thing is when you don't want the neutrons to really hit this tube even though aluminum is nearly transparent. If it hits in this inclined angle. When neutrons get absorbed actually they create gamma radiation. And that will in turn maybe cause your radiation problems of your beam line and then also if it's close to the detector create noise in your detector and a lot of these kind of things. So simple trick there is to put beam strippers inside. And you can see on the top to just catch some of the neutrons that anyway won't reach your sample and detector. And by detailing what material you can put in there you can create gammas of different energies that are not so problematic. And the next thing is so if you transport neutrons a very long way, like ESS actually owed in 60 meters long and we have many instruments they are 160 meters long. And in order for any neutrons to reach to your sample and detector actually you need to use neutron guides. What it basically is the neutron that you can just imagine it as a mirror for neutrons. And they just bounce back and forth inside of there. And at the end nearly loss free come out at the end. But they come out of course this is divergence at the end as well. And that will create blurring on your sample after all. And what's important here is a lot of developments happening in these neutron guides and what there's a critical angle where actually neutrons are still transported. So there's a standard guide, which is based on nickel, and then there's something called a super mirror guide concept, where you can multiply this critical angle by a parameter m. And that is shown here if you just look at this graph on the bottom left. So by a higher m value you get a lot more neutrons through your guide. Of course this will come at a big cost as well every m layer will add more cost to this. And of course that whole divergent things and also again wavelengths dependent. And if you do imaging on a neutron guide, instead of I mean the other possibilities, if you are on on another, if you're close enough to your source you don't have to use any guide and just look at it directly. They can also have certain advantages but also disadvantages but when you do have a guide, it also introduces some stripe structure that you can see from the guide on the images here to the right. And then doing a different pinhole will change that and you can put some filters in there to diffuse this pattern. But after the normalization that has the undersides also shown the open beam normalization these patterns will anyway vanish. But they do look quite striking, as you can see here. Going on a bit with instrumentation other beam conditioning that can be done. So for one thing, if you don't use a neutron guide on our curve guide. You will have, I mean both at a reactor and also at a pulse to us, you will have epithermal and fast neutrons coming through that you don't really want for mainly radiation purpose but then also for background purposes, especially for imaging that's problematic. And in a pulse source that always comes in a flash there. And one way to filter that out is to use something called a heavy shopper to zero shopper. And where it's a very big hammer that rotates the same frequency as your neutron source and catches this prompt piles every time when it rotates around so you don't see these on your sample and to get rid of these. And the other method you can use is to use a curve guide. And this is shown in this example so you have fast neutrons and gammas. But what you are interested in is thermal and coil neutrons. So if you use a curve guide. You're a thermal and coil neutrons travel to your sample and and detector, but this guy doesn't direct the other neutrons to the sample and detector and they just hit the wall and the shielding outside. That however has a little bit the problem that these multiple reflections in the guide create this divergent beam and then could result in unsharp images. And the way to do it then is to put like a pinhole diaphragm in there and a flight tube and create sharper images this way. So it's a lot of instrumentation concept that you need to think of and you should also think what imaging instrument you use what artifacts. You may get in your image and what becomes important on how you set up your experiment based on all these considerations. And this to give you an example when you collimate the beam. To do this type of collimation the instruments typically have some selector here in Munich at Antares imaging instrument at FM2 they're having a drum, the six different collimators that you can select and often in a proposal, it can be very beneficial to already state what collimator you want to use so like what L over D ratio that you already learned you want to use that is selected this is collimator. And then when you want to have a monochromatic beam. At a steady state source you can use a neutron velocity selector where these lamellas is rotating at a set speed, and only neutrons of a very certain wavelengths actually are carried through this lamella for one side to the other. And then you have a quasi monochromatic neutron beam when they come out to the other side and all the others ones are absorbed with a different speed in these lamellas. Or you can use a double crystal monochromator that is tunable where a neutron hits a monochromator on one side bounces back to a second monochromator and then carries on into the same direction after that. And this is now showing a generic pulse instrument where we have a spallation target on one side, and then the neutrons are moderated as I described, and then they travel through neutron guide to give you an idea of the speed of neutron that you can get some sense of how fast is one angstrom neutron. You can see it on this table here, and 10 angstrom neutrons and travel 400 meter per seconds. And then you can see in a two meter distance of one angstrom neutron needs one millisecond and 10 angstrom will need five milliseconds to give you some sense of of the times and so on. And then these neutrons, they are all created at the same time, all the wavelength at the same time at the moderator they travel to your detector, and here they are now separated by their time of light. And what you see here if you look on the x axis you can see at even at five milliseconds and 10 milliseconds, this is not zero. And this tail that you are seeing it touches to the end where it's 60 to 70 milliseconds. So there's like a run over of the same neutrons into the next pulse of the repetition. That is called pulse overlap. And to get rid of that we use shoppers that are rotating at a certain frequency and have an opening and absorbing neutrons at the other time. And with that you can shop your spectrum to either get rid of the fast neutrons, and you can see that part of the spectrum cut, but the cold neutrons that I have that's the blue tail and the arrows on the bottom. And it's the neutrons of the long flight past 60 70 like this would correspond actually to like 90 milliseconds. And that's still there. And they you can cut this cutting on the different side of the spectrum and now you can see at 60 milliseconds the whole spectrum being cut, and you don't have this frame overlap anymore. So this tuning the shoppers to different frequencies and opening you can cut on a pulse instrument. And then this can be directly translated the time of flight to wavelengths. So there's a one to one relation between the time of flight and the wavelengths. As I said before, like, you may also need to think about adding a T zero shopper especially if you don't have a curve guide that is also rotating at the same speed and everything is then synchronized to the source. And just as a side note again that you don't get confused maybe when you read your research paper other things, you can create a pulse neutron source also at a reactor by just using an additional shopper that has just served the purpose to create a pulse neutron beam, as you can imagine. So you can just pile the beam in every so often. There's more lectures on all of this tomorrow. So I think I will just carry on with this lecture the next part of the beam time proposal writing is anyway, I will not need the full 15 minutes so I think we can manage to go through what I have left here. There's a few words on neutron detectors, because that has been really also developing quickly developing field. And I wanted to show you this slide but then in preparation of this lecture I couldn't really find I saw that this was outdated so I will not show you that slide now. I will try to fight up to date one or create one that I will put in the online version of the lecture later because it shows nicely what type of detectors are available and what spatial resolution they offer versus what time resolution and so on. But as I said since this is so quickly developing this is not up to date. I mean, until not so long ago. One method to do new imaging was actually using imaging plates. And when you look at papers even up to the 2000s. They look like figures in the papers look like what you see here in this figure for that I just screen took a screen screenshot off. And there you need to use a, you put this imaging plate, it's just like a film, you can envision in your instrument, and then you need to take it later to a developing station to digitize to digitizes, of course this is extremely impractical. It's still being used at some of the neutral facilities and in principle, it can have a better spatial resolution than any of the digital ones because it's not a digital technique but analog. So it doesn't have in principle this limitations of spatial resolution on based on pixels. So maybe I would claim it is history, but maybe some special application this can still be useful. This detector setup really is the past, the present and the future I would say, and it's also widely used in X-ray and all sorts of imaging techniques and what you use is just light sensitive detector that can be a CCD and CCD has been the gold standard for any imaging applications. You put in some light type box and you have a scintillator that you can see on the front left of this or also in green on the right image. And this scintillator basically with the interaction mechanisms that you have seen earlier in some lectures, basically through nuclear reaction creates visible light. The light is then reflected by a mirror into the camera and the reason why you're using a mirror, maybe does somebody want to answer why do you use a mirror and don't put the camera behind. Anybody want to have a wild guess? I think I talked about putting your iPhone in a beam yesterday, it's the same reason I guess. You can get frustrated with an iPhone, but yeah, so you don't want any of the radiation damage to occur there of course. And so you're just bending it out. And again, I have a question for this light. So if you have a geometry like this, how do you define the sample to detector distance them? Good question. So if it's, I mean maybe drawn a bit, so if you just focus on the, do you actually see my mouse when I move it? Yeah, so you would just position your sample where it says neutrons here on the slide and if you put it there where the S is, you get closer. So you have a big space before that. So your sample sits there where the blue light is in front of the detector. And it's important actually like how you design this box, how close you can get to it, especially if you have some complicated geometry. Does that answer your question? But what would be the actual distance, like how to measure the distance? How do you measure it? It's a very good question because it's often very tricky. It really depends on your sample. I mean you can use a ruler if you're like millimeters away. I mean typically you look from the side to it and there's no, I mean, you don't need typically to know that precisely you want to get it likely as close as possible. It's not a critical information if you don't have it and you may don't know the exact distance anyway because it's, I mean with a scintillator maybe it's easy enough but usually there's an aluminum shield in front to protect and the scintillator sits actually on the inside. So you still don't know maybe exactly where the neutron is converted to visible light and then some other neutron detectors even have a bigger active volume. So you want to get as close as possible but how close it really is is only really important if you want to characterize your imaging beam line. Okay, thank you. Thanks. And a big developing field is of course having neutron detectors that can do a time of flight. The system that I just showed is a counting type detector so it integrates over time. All the counts it doesn't discriminate the timing of the neutrons. So, big development project have an R taking place to build detectors that have both spatial resolution and time resolution. And this is just showing some of the detectors that are available for example at the Jay Park pulse neutron source. You can see detectors, this micronate that you can see on the top have a 10 by 10 centimeter active area, but the spatial resolution that is only 200 micrometer. That's fairly coarse compared to what this other imaging detector could do. And maybe Nikolai has shown you can get to a few micrometer spatial resolution and this is 200. This NGM detector even larger spatial resolution of only one millimeter. So this is not really competitive to that but you get more spectroscopic information when you use this type of detector because of this pulse information. Another imaging detector that has a better spatial resolution and so far the best possible spatial resolution is and was based on microchannel plates. So I again put past present and future for this technology where neutrons are converted in this microchannel plate so it's a plate with very many small holes this channels and this material is dope with some converter material or natural gadolinium, and then it reacts like a photo multiplier tube to have a charged ever launch that can be detected on the other side of these plates. And it's a fun fact this is also how these microchannel plates also how night vision goggles for example just not this neutrons but this light. This detector that is really shaped the field of time of light neutron imaging was developed actually by a very interesting character Anton Tremzin was based in at the UC Berkeley of Russian origin and he's traveling with his detector all around the world. And to do experiment with so I had and still have the joy of working with him. He is really great and this detector, however has a relatively small field of view of 28 by 28 millimeters. But it can do very high count rate where other detectors are severely limited. And it has the best spatial resolution. What should I put this off a best spatial resolution of any detector with a pixel size of about 55 micrometers and actually the time resolution is even much better than needed for most application that this detector can do. There's a couple of shortcomings as well of it that there are some readout gaps in between as well. And what I like to show in this slide basically is just to show that this is doing a lot of this is creating a lot of data when you do time of light neutron imaging so a typical experiment can easily result actually in a terabyte of data after just a few days of measurement and this is an example done at J-Park and we expect even more data to occur when ESS. And actually the same detector concept is not only the past but also the present and future because what we did we just stuck in a fast CMOS camera and set of the CCD. And then it can be already used to do sim to do simple time of light imaging with such with the same camera setup just switching the detector. And even more so really the future there has been some recent work where they didn't switch the whole thing for CMOS camera but actually for a time pick 3 cam. So the ship is actually the same as this mcp detector from Anton Tremson that I showed earlier, but now coupled to a light sensitive light to make it light sensitive. And then this actually what they've shown in a recent paper that is still on a preprint server right now that they can discriminate not only photon clusters on the scintillator but really back calculate individual neutrons and neutron counting. And actually there's a nice seminar online on YouTube that you can watch the Adriane who built this detector who is based in Munich now in Los Alamos before is presenting this technology. And I believe that can be really a game changer now in this field. And with that we have reached 50 minutes so I will just now really skim over some instruments and then go over to the beam time proposal. This is an example now of an imaging beam line and NIST in Gaithersburg in the US. So you have the reactor vessel in the middle and all the components that we already talked about. And then you have some big heavy concrete that is in yellow and neutron flight tube and so on in there and then at the end you have a neutron detector. And this is at a 20 megawatt reactor. So use this slide just as your reference for later if you wish, I will not go into all the details. This is the instrument where Nikolai was the beam line scientist Conrad. The concept is similar neutrons are coming from a neutron guide you have a pin oil exchanger. And you have some optional beam conditioners like monochromators or velocity selector you can move in and out of the beam. And then you can have different detectors a higher resolution position or large detector at the end. And this is how it kind of looked like in practice on 3D. And at PSI. It's a similar instrument this is the one that has a thermal neutrons from earlier called Neutra. And what I like to highlight here that it at the same time it allows that they can translate an x-ray source into the neutron beam so whenever the neutron beam is not on. They can actually do x-ray imaging instead and then do it in the same geometry. So this is the present and we see more and more beam lines, building up x-ray complimentary and there's also termed this the future. And the same they're also doing at PSI at the icon where Anders is the beam line scientist. And there they have actually an x-ray source 90 degrees towards the sample so they can do x-ray and neutrons simultaneously. And this is also actually what they can do at this new imaging instrument at the ILL and what's worth highlighting here that ILL is the most powerful neutron reactor a research reactor in the world. And it's not only imaging until just a few years ago, but then the community really has pushed for concept and this type of beam line and it's something that really came from a bottom up approach in in building an imaging beam line at the ILL. And it's an excellent beam line now that is operational and what they have done also early on this is x-ray and neutron 90 degrees simultaneous measurements and then you're getting to image data sets at the same time you get your neutron and x-ray and Anders will talk about this in detail again on bimodal imaging and you already shot some examples. And last but not least, some examples from pulse sources. So the Raden instrument at J Park is that one of those particle accelerators. And it actually was the first dedicated tower fly neutron imaging instrument at the pulse source started in 2015. And these are some of the basic parameters of the beam line. I like to show you just a brief video, maybe you can indicate if you can hear the sound briefly. Join your symposium all in Japan at the J Park Neutron installation source doing neutron imaging and detractors. So it's just showing a user experience. This is Morten who was at DTU in Copenhagen before and just a quick video showing a user experiment at Raden. As you can see, the experiments are going well because I'm here, not in the hutch. And I thought I'd take this opportunity to briefly explain to you what we're here to measure. The purpose of our measurement is to investigate the properties of lithium batteries when they're being charged and discharged. Here, Monica is doing the final assembly of a battery in an oxygen pre-argan atmosphere. The metallic lithium and the graphite anode are installed inside the cell in an electrolyte solution, and we will be using energy-resolved neutron radiography to obtain bracket spectra with spatial resolution. We are measuring at the Raden instrument, and here Monica is opening the gate to enter the instrument so we can check the sample position. In order to measure the time of flight signal, we are using Anton's micro-chain plate detector, which has spatial and temporal resolutions necessary for our investigations. You can see the battery cell just in front of the detector. On top of the instrument shielding are the computers controlling the detector and the potential state for the battery. Here, you see Monica and the instrument scientists have now tested the sample that will be measured for the second part of the measurement. Where we will use Raden's polymetric setup in order to measure the three-dimensional spatial distribution of the current flow through the sample anode. Afterwards, we will change to the next experiment at the center diffraction instrument where we will measure a polycrystalline-shaped memory alloy. We are combining diffraction and imaging data to get both the crystallite shape and orientation within the sample, and we will be applying pressure onto the sample to see an in-situ-based transformation. As you can see, you can also, when you do such an experiment, you can eat some awesome seafood during this experiment and fuel up like that. So that has given out for you some sense on how the beam line looks like and what you may need to prepare. This is I think the last beam line that I will show that the other operational pulse neutron imaging instrument called IMET at ISIS in the UK, close to Oxford. And this is showing the beam line how it looks like and what I like to highlight here because this is also a trend and likely the future to combine imaging with diffraction. And they're already having diffraction module set up so it's really not only an imaging instrument, but also a diffraction instrument. So can do powder diffraction and stress strain analysis. This example here is just showing what you can also do in diffraction is you can this is a single crystal turbine blade for example when you rotate that inside the beam you can see on your diffraction detector. And now the crystal rotating, and you know then the orientation of this crystal in the beam from looking at the at the diffraction detector that is set up in there. And another thing just worth highlighting in regards to before is, is the wavelength resolution versus the wavelength of the short pulse source so again like just use these slides as a reference for later. And I do believe I should be coming to an end. No, I had ESSS the last example I apologize because that's really the future so I hope we are still in time we are reaching the one hour limit now. So ESSS has this really long pulse and here you can see really in comparison to other pulse sources that have a much shorter pulse. ESSS is very intense intensity as well but then when we need higher resolution we need to pulse shape and cut away from this long pulse to make it essentially a short pulse source. And these are typical frequencies ESSS will operate at 14 hertz, ISIS operates at target station 2 at 10 hertz and target station 1 at 50 hertz and SNS at 60 hertz and so on. So they are also operating on a different frequencies. So I already said will be 60 meters long. And there's a lot of shoppers in the beam line then you have a huge experimental hutch at the end. And what is really here the key is that you can use either all the pulses from the source, or you can also skip every 14 hertz every second pulse of the 14 hertz. Or you can cut this pulse into shorter pulses and use a technique that we called wavelength frame multiplication and you are increasing your wavelengths resolution by cutting like this. So you need to operate a lot of shoppers all synchronized very well. So that was now my last slide.