 Άνας δημιουργία στις ψοιτηρισμόνες για την blended analysis. Ε 많ε θέλει να το δοκιματεύει τα τονιακή φυσική. Δευτερό για την generally analysis που δεν θα χρειαστεί σε πολλοποιία silence. Εκεί σε μικριοτασμένου σκληρémonνη, καταλαβαίνει την βασική φυσική, τα βασική φυσική μετακύπουυ, μπορείς να λατουργήσεις πολλοποίηια από τα ταικνάτιια. Όλες αυτές τις τεχνικές είναι χρησιμοποιηθείς για να αναγνωρίζονται σαμπλές, για να αναγνωρίζονται αν θέλεις ματιρίες. Όπως βλέπεις, πιστεύω ότι μεταξύ με το τρόπο που θα χρησιμοποιηθείς, θα θα χρησιμοποιηθείς διαφορετικότητα για τη ματιρία σας. Ή always our target is to identify the material, to characterize it. This means that understand what is made of the elements, understand if we can, the concentration, find out the concentration of each element, and in some cases, in some techniques, you can also see what we say depth profiling, so you can see how the concentration of an element evolves as you go deeper in the element. So I'm going to talk to you for two hours, unfortunately for you, about RBS, which stands for rather for backscattering spectroscopy, ERD, Elastic Recall Direction Analysis, and then Nuclear Reaction Analysis and the Proton-induced Gamma Ray Emission. I'm not going to talk to you about PIXE, I'll just give you three or four slides just for the completeness of my talk. You will have special talk about PIXE, because if you want the PIXE is the workhorse of INB analysis techniques. Whenever you talk with somebody who is playing with INB analysis, he will talk to you about PIXE. Everybody loves PIXE, you will understand why, hopefully. So this is the outline of my talk, I'll give you some general things about INB analysis. I'll guide you through the theoretical background, which is not very hard, it's very simple, the theoretical background, and then I'll talk about PIXE, PIGE, RBS, NRA and Elastic Recall Direction Analysis. As you will see, with this INB analysis techniques, you can do many things. The most common target for us is archaeology, and if you want cultural heritage. And why is this? This is because as you will see, the main advantage of INB analysis techniques is that they are non-destructive. You give me something, I analyze this, I give it back to you as it is. If you are talking about, for example, I don't know, let's say, semi-conductors. Somebody who is producing semi-conductors, he normally produces 10,000 per day, a huge amount. So even if you destroy them, they don't care. You can do whatever you want with them, break them, put them in acid, they don't care. They have a huge amount of them. But if you are talking about unique artifacts, and this is cultural heritage, if you are talking about a painting, if you are talking about some jewelry, this cannot be replaced. So there you cannot intervene. You have to play with some techniques that they are not destroying your sample. And these techniques, hopefully I'll persuade you that it's INB analysis techniques. This is a provocative logical flow chart that I'm using always. It's just to show you where we stand for. You have what we call the client. Client, OK, it's not a nice word. Let's say that he's a scientist from another field of science. Let's say that he's an archaeologist, he's a conservator, he's a chemist, he's whatever. And you are the analyst. You are the one who are going to analyze the samples. You are the one who is going to apply INB analysis techniques. It's good from the very first step to understand who is going to do what. And this, I tell you, because many times you will see that these guys over here have some, let's say, questions that you cannot answer, or they have some things that they want to be done that they can't be done. And this must be clear to them from the beginning. So the scientist, the client, let's say, has a question. For example, I have this thing over here. I want to know how much hydrogen is in this thing over here. The first thing he has to do is to discuss with you. Can it be done? Yes or no? Is it possible? Can I do it? Yes or no? This is the first thing he has to do. Most of the times, the analyst is also responsible for the accelerator who is going to work, or he co-works with somebody responsible for accelerator. And then both of you, you have to discuss and decide about the sample. What is the sample? How big is it? Is it proper for you? Can you use it? Yes or no? After that, you will be responsible for the experimental setup, the data acquisition, and the analysis here. I want just to tell you that there is a big difference between analysis and interpretation. You can give numbers. For example, in the previous example, you can go back and tell them, OK, I found that you have 10% hydrogen into your sample. It's not your job to say how this hydrogen got in there. You don't know. It's not your science. It's not your part. The interpretation of the results must come between both of you. You can tell them what you saw. I found this and this and this. I found this depth profiling. I found that with hydrogen, you have also oxygen, or you have some iron, or whatever. But how this thing entered into the sample, it's their job. So at the end, after this process, they will take their answer. So let's see what are the good things about IMB analysis and what are the bad things with IMB analysis. First of all, I want to make clear that IMB analysis, it's not Panakia. It can't solve anything. OK, it has their restrictions. And for me, it's more important for you to know the restrictions than to know what you can do with IMB analysis. What are the good things? First of all, in the older years, we said that they are non-destructive. This means that whatever you bring me, I can analyze it. And then you take it back with no damage. In later years, we became, let's say, more careful. And we say least destructive. As you will see, some damage can be done if you are not careful of how you are going to apply the IMB analysis techniques. At the end of the talk, I have some examples to see how you can destroy a sample, a delicate sample. The second good thing, it is that IMB analysis are multi-elementary. This means that with one hit, with one experiment, you can take multiple information about your sample, almost all the elements, especially for a pixel. With just one experiment, you can find the amount of aluminum, of silicon, of carbon, of almost whatever you can think. You don't need any preparation of the sample. You use the sample as is. You don't have to coat it, or to clean it, or to polish it, or to cut it, anything. Just as it is, you can analyze it. Sorry. You don't need a big quantity of the sample. Your sample should be, if we exclude microbeams, it should be something like 2 millimeters times 2 millimeters. If you put in the game microbeam, then you can go down to 10 times 10 micrometers square. So from very small samples up, let's say, to 5 or 6 centimeters square, OK? Now comes the bad things, OK? This is the first thing I told you, that if you are not care, you may damage your sample. For example, you have a beam. The beam has energy. When you start heating your sample, the sample is going to heat up. If you don't care, and if you put a lot of beam on it, this will start heating. If it's delicate, you may burn it. I have opened holes in aluminum just for fun. The second bad thing is that you need an accelerator. And as you know, accelerators are not portable. So this means that whenever you have a collaboration with somebody, this somebody has to bring the samples to you. You can't go there. It's not like XRF, for example. And maybe you know that now XRFs are small guns, like that, an XRF, portable XRF. You go on site, you just heat, and you have your analysis, OK? You will never have that with IMB analysis. Why? Because you have an accelerator. An accelerator is huge. You have to come to the accelerator. You can't go there. OK, leave it. This is a small thing that you have to know some nuclear physics. You may not take the novel of nuclear physics, but some nuclear physics are needed in order to understand what you are doing and in order to analyze the sample. This is very important. Whenever we are talking about IMB analysis techniques, forget chemical reactions. Forget bonds. Whenever you are talking about IMB analysis, you have interaction between nuclei and nuclei. You don't have interactions with electrons. This means that when you analyze something, you can tell them that it has so much, for example, iron, so much oxygen. You can't say if this is a Ferum II oxide, Ferum III oxide, or whatever else. You don't know the bonds between the elements. Maybe you can extract them, but let's say this is just looking at the proportions. If, for example, you see that you have aluminum and you have 20% aluminum and 30% oxygen, then you may say that this is alumina. This is aluminum trioxide. But this is not direct from the results. From the results, you will take only concentration of elements. The other thing that you should know about IMB analysis is that they are purely surfacial. You can analyze up, let's say, to 100 microns of the surface. Not more. It's not bulk analysis. So if you bring, let's say, this phone over here and tell me that you want me to analyze it, I can analyze up, in the best case, up to 100 microns from the surface. I can't see what happens inside. And the other thing is that as you will see many times, I have to combine different techniques in order to take the whole information that I can take. You will see, for example, that PIXE is not suitable for analyzing things that are lower, elements that are lower than aluminum. So for example, if you want to see, if your sample has, let's say, iron and lithium, then you have to combine PIXE and PIXE. PIXE can see iron, PIXE can see lithium. If you want also to see carbon, then you have to put into play nuclear reaction analysis, which can see carbon. So depending on the information you want to do, you want to take, you want to extract, many times you have to take more than one techniques. Many times you can do that simultaneously. So which are the IMB analysis we are talking for? All the IMB analysis have to do with interaction between accelerated charged particles. OK, that's why we call them IMB analysis with your material. Now, depending on what you are going to measure, you have a different technique. And depending on what you measure, you also take different information. So let's say that I always use proton as an example, as my own, as my ion beam. If my protons interact with the elements, with the materials into my sample and I detect gamma rays, then I say that they perform a PIGE proton induced gamma ray emission. If my protons are backscattered elastically from the elements and I detect, again, protons, then I'm talking about rather for backscattering. If my protons excite the elements over here and I detect X-rays, then I'm talking about PIXE. And if my protons do a nuclear reaction with something here, for example, a P-alpha reaction, so I throw protons, I have a reaction, let's say, with beryllium and I take back alphas and I detect the alphas, then I'm talking about nuclear reaction products. So depending on what I'm going to do, what I'm going to detect, I have a different technique. Of course, this means that I have also different information. And because ions react differently with different elements, depending on what I want to see over here, I will choose the best method to use. I also have recoil-erda, elastic recoil detection analysis. This means that I use a heavier ion beam, for example, chlorine-35, and I kick out lighter elements. This is very good, as you will see, when I want to detect hydrogen, deuterium, helium, or whatever exists over here. So theoretical background, as you will see, it's very, very simple. Hopefully, you know everything about that. This is just what a nuclear reaction is, and this is a very simple formula, a very simple definition of the cross-section. What is a cross-section? It's the probability of a reaction to a cure. So what I have here, I have the number of detected particles. Here I have the number of incident particles. This means my beam. Here I have the number of the elements in the target. Most probably, this is what I want each time to find out. And this is the omega, is the solid angle of my detector. It's just something, let's say, constant. Very simple formula. I hope most of you already know it, maybe in different formulas. But it's very easy. Now, the second thing that I'm cared about, we are going to talk about energy-struggling, stopping power, when we are going to talk on Thursday about detectors. But this is something very simple to know. Whenever you have an ion, whenever you have a beam entering in a sample, what happens? Your beam will find out some electrons of your sample, okay, free electrons or bound electrons. It will react with the electrons and then we'll start losing energy. And this is what we are calling energy loss. Your ions may lose energy in a matter, most probably, by two things. Either reacting by electrons, the electrons of the matter, okay, or by the nucleus. This is not so important as the electronic stopping power. And of course, the stopping power is the sum of the two. Here, just one plot in plain Greek, as you can see. So you can also learn Greek. This is the energy of my beam. And this is how much energy they lose depending on the sample. So with blue ion, I have copper. With red ion, I have silicon. And this is just the electronic part. The energy my ions are losing because of the electrons into the element. Sorry. And in this small insert over here, you have the nuclear part. As you can see, I am about almost two orders of magnitude. So to be honest, nuclear energy loss doesn't play a significant role. And this is very easy to see it if you see it just from a classical mechanic. When you have a material, you have some centers where you have the nuclei. And the whole space, it's full of electrons. So it's more probable for an ion to interact with the electrons everywhere than with a small center which is the nucleus. And this is just to prove you. These were some old photos from the old days where people were doing two bad things in parallel, being in the beam and smoking. And here, just to see, air is a medium, okay? So whenever I extract my beam outside, it will start losing energy. So this is a 7 MeV beam energy. You can see that it can reach in air about 60 centimeters before losing all its energy. And also having mind that it spreads, that it opens also, okay? It's not like a laser going in a straight line. As you are losing energy, you also deflect from your original trajectory. While if you use a 300 KV beam energy, you can't go further than one centimeter. And this is all the things you need to know in order to understand ion beam analysis techniques. It's all the formula you need. You don't need more complicated nuclear physics than that. In the beginning, I talked to you about depth profiling. This is, let's say, our ability to see how the concentration evolves from the surface deeper in the sample as you go. So if you can distinguish and say that aluminum is 90% in the first one micron, then it drops to 70% in the next micron, then drops to 30% in the third micron, then goes up to 50% in the fourth micron, et cetera. So you can see how the concentration evolves as you go deeper into your sample. This is what we are calling depth profiling. Some of the ion beam analysis techniques are good at that, and some of them are unable to provide this information. Okay, so this is the first thing to know how you are going to select an ion beam analysis technique. Do you want the depth profiling? Yes or no? Which techniques are capable of depth profiling? RBS, that's for backscattering. Forget NBS, I'll tell you later. ERDA, Elastic Recall Detection Analysis, and Nuclear Reaction Analysis. Which techniques are not capable of giving depth profiling? PIXE, can't give you that. Neutron activation analysis can't give you depth profiling. Charge particle activation analysis are not giving you depth profiling. And in the middle you have PIGE. PIGE is, let's say, a special situation because depending on what you are going to detect, maybe it can give you depth profiling, maybe not. For example, if you are going to use PIGE in order to detect aluminum, yes, it can give you a depth profiling. If you are going to use it in order to detect sodium, no, it can't. As you will see, this depends highly on the way that protons, protons is the usual beam we are using about PIGE, how protons interact with the element you are going to detect. And just to be more precise, as you will see, depends if there are, in the cross-section, if there are resonances or not. If you have sharp resonances in the reaction between protons and the element, then you can use these resonances in order to depth profile. If you don't have, you can't do anything. If you look at the cross-section of proton with aluminum, you will see that it has very sharp resonances. For example, there is one resonance at 992KV, that almost all people are using for machine calibration of the accelerator. And you can use this resonance in order to depth profile aluminum. If you look at the sodium cross-section, you will see that it's very smooth, very nice cross-section with no sharp resonances. So there, unfortunately, you can't do anything. You must find another way if you are eager to find depth profiling. As I told you, the first thing you need is an accelerator. In most of the time, this is our accelerator in Athens and various setups we have. Some of them, for example, micro-pixel over here, the external beam, the charge particle, x-rays, the RBSN-RH chamber, are dedicated in IRB manual techniques. Some others are solely for nuclear and atomic physics studies. Just keep in mind that if you want to perform IRB manual techniques, you need small accelerators. What I mean is small. You need, most of the time, electrostatic, either van der Graafs or tandem accelerators. Cyclotrons are not ideal for IRB manual techniques. And the reason is very simple. In most of the IRB manual techniques, you have to know very precisely the beam, the energy of your beam. Small accelerators like tandems or van der Graafs have a precision of around one per mil in your IRB analysis, sorry, in your energy. So whenever you are using a 2MV proton beam, this is plus minus 2KV. Whenever you are using a cyclotron, this doesn't exist. When you, for example, you have 20MV protons, these are plus minus 100, 200KVs, which is not very good if you want to do precise measurements in IRB analysis business. This is a second accelerator. This is not ours, of course, okay. This is Aglae. Aglae stands for Accelerator Grand Lug de Analyse Elementaire. This accelerator is situated in Louvre, Paris, at the basement, and I have it as an example because this is the only accelerator existing just for IRB analysis techniques, just for cultural heritage. They are specialized in that. They have built this accelerator just for that. Many times I have asked the guys why they build an accelerator and why they don't go somewhere else to make the measurements because, of course, France has a lot of accelerators and laboratories. What they told me, maybe it's a joke, I don't know, is that it was cheaper to build an accelerator in the basement than giving money to take the artifacts outside from Louvre, take them somewhere else to be measured and take them back. Because there you need a lot of money because of security, transportation, things like that. We are talking about cultural heritage. It's not trivial. Oops. Okay. First things first. So, samples. What they can bring you are samples and you can expect them to be measured. Three possibilities. First of all, under vacuum, most of the times, in 90% of our business, we want to do our measurements under vacuum. Why is that? Because, as you have already seen, I know very well my energy, the energy of my beam. My beam doesn't spread a lot. So, let's say that under some, under vacuum, I have more controlled situation. But if we are talking about analysis under vacuum, then we have to take into account that we can only analyze small samples up to 10 centimeters, okay, you can't put a statue into vacuum. The thing you are going to analyze must withstand vacuum. For example, you can't put under vacuum wood. Normally you can put wood, but you have to wait about, I don't know, 10 days in order to achieve vacuum because wood is porous, it has a lot of air, you have to wait a lot. And we never put, for that reason, we never put wood under vacuum. Most of the times, we prefer the sample to have good electrical conductivity. So, we are talking about contactors, we prefer contactors. This doesn't mean that we can't analyze glasses, but we prefer them. And when you are doing the measurement under vacuum, you have greater accuracy into your results. Now, if your sample is big enough, a sample, then you can use an external beam. What's an external beam? It's a simpler way, as you will see, to extract the beam into air, then take your sample, put it as close as to the nozzle, to the exit nozzle of your beam and do the analysis there. There, things are better because you don't have any limitation, you can put whatever you want. You don't care about vacuum. Most of the times, you need a flow of helium between your beam and the sample, but you have limited accuracy. This means that if you give me the same sample and I analyze it under vacuum, I can give you an accuracy of, let's say, 3 to 5%. If I do that in an external beam, I'll go up to 10%. If you don't care, I don't care, also. It's not my problem. Remember that whoever brings the samples is also the guy who is putting the restrictions. Okay, if he tells you, for example, that I have a big sample, I want you to tell me if it has hydrogen inside, yes or no, then you can do it in an external beam. You can say yes or no. But if he tells you that, look, I have this big statue, I want to see hydrogen inside and I want the accuracy of 1.5%. Okay, this is possible. You say no, excuse me, because I have to put it under vacuum. It's a statue. I can't put it under vacuum. And on the other hand, even under vacuum, 0.5% you will never achieve. So just forget it. And then we have also the microbeam. So with microbeam, you can go to even smaller samples that this over there, 10 centimeters, you can go down less than 1 centimeter, you can go down to millimeters because your microbeam typically is something like two times two micrometer square as a cross section. And also it give you another big effect. You can do a metal mapping with microbeam. This means normally that you can scan your sample with your microbeam and take information from each pixel of the sample. I have some examples. You will see them. This is a typical external beam. So this is the real thing. Your beam comes over here from this direction. At the exit of your external beam, this is a small window of silicon nitrate. It has a thickness of around 50 micrometers. So this is something very thin. We are using silicon nitrate because it can withstand a big difference in pressure. Think that behind this silicon nitrate window, you have a vacuum of 10 to the minus 6, 10 to the minus 7, while here you have an atmosphere. So the tension caused by the pressure over here, it's very big. And around that system here, you bring the painting, of course, cannot enter into vacuum in a very close proximity. And around that, you have all your detectors. So here you have a silly detector for pixel. Here is a high purity German detector for pg. Inside here you have a surface barrier detector for RBS. And here also you have another pixel detector. Or if you can look it over here, you have a pixel detector here, a pixel detector here. Over there is the RBS detector. And here is a high purity Germanium for pg reactions. Most of the time, yes, 99%, you can also extract heavier things. For example, you can extract also alphas. The thing is that with alphas, you won't do any pg and you won't do any pixel. So you can extract alphas, but then you are limited to do something like RBS or nuclear reaction analysis. The second bad thing is that this thing gets hot. So if you are using a heavier ion, like let's say carbon, this means that here you leave more energy. Remember what we talked about energy loss. More energy means more heating. More heating means it's going to break more easily. So 95% of the situations we are using protons. Protons between 2 and 3 MeV. Pixel. As I told you, you will have a separate election about pixels, so I just give you some hints about pixel. Pixel is something very easy. It's not a nuclear method. It's an atomic method. What happens is that you have your beam, the beam passes through your matter. It finds an atom. It takes out an electron. It ionizes an electron from your atom. It leaves here a hole and then you have an external electron who is going to fill in the hole. But in order from this cell to go down, it needs somehow to expel energy. Somehow it has to give you some energy. So what it does, it throws an X-ray and it goes filling the hole in the inner cell. If you remember, and I hope you remember from atomic physics, depending on the element, the position of the cells is very well defined. This means that in order to have the transition from this cell to this cell, the energy of the X-ray that I'm going to take, it's very specific and it's characteristic of the element. For example, if I see an X-ray of, let's say, 15.3 EV, then I know that this comes from aluminum. If I see an X-ray of, let's say, 27.8 EV, then I know that this comes from silicon. So what is the trick? The trick is that I'm bombarding my element, I detect X-rays and I'm looking at the energy. Dependent on the energy, I can identify the element that exists into my sample. This is a procedure, this is something that just to play, I hit outside the electron and then I have another electron filling up the sample, giving me the X-ray. These are the typical detectors that we are using for pixel. It's either silicon detectors, semiconductor detectors doped with lithium or now we have also HDD detectors. And this is a typical microbeam setup. So, pixel. It can't give you, as I told you in the beginning, anything about depth profiling. Why? Because X-rays are not heavily attenuated in any element. So if my X-rays come from the surface, from one micron deep, from two microns deep, from five microns deep, it will be always the same energy. And as I detect the energy of the X-ray, they don't lose any energy as they go through the sample. I don't know from where it comes. I just count an X-ray of an energy, as I told you, 15.3. If it comes from the surface, from the first micron, from the fifth micron, I don't know. I don't have any reason, any way of knowing that. So if you want depth profiling, forget pixel. Where you are, when you are under vacuum and if you have a very good thin detector, you can detect from carbon and upstairs. So if you want to detect aluminum, iron, copper, it's perfect. But if you want, for example, to detect lithium, forget it. If you want to detect hydrogen, forget it two times. If you want to see also carbon, it's not very well seen. To be honest, in most of the times, you start detecting with great accuracy from aluminum and up. Whatever it's below aluminum, find another method. Forget pixel. It's because of the energy of the X-rays. It's very small and it's attenuated even in air. Also, your detectors have some windows always. And this windows is used as an absorber for light element X-rays. No problem. No problem with me, as you like it. This is the main reason. The energy of the X-rays, it's very low. This is a typical, let's say, typical spectrum. What you will see, this was taken from a silicide mineral. And these are the peaks. Each peak corresponds to an energy. Each energy corresponds to an element. So, for example, this peak over here corresponds to iron, magnesium, titanium, calcium, rubidium, et cetera, et cetera. You integrate this peak and you have some first results. As I told you, I won't stick into pixel because you have a special talk about that. This is the same thing for the analysis of potteries. Again, you can see here various peaks in various energies. Each energy corresponds to an element. Just have in mind that many times you have two or maybe three peaks from the same element. And why is that? Because, as I told you before, how pixel works, you ionize your sample, your atom, and then another electron comes and fills the position, the empty position. Depending on what electron you are going to ionize, you may have the KA or the KB or the LA or the LAB because you are not always obliged, of course, to ionize to hit the electron on the first cell. You may hit the electron on the second cell or the third cell and leave a hole over there. So the energies always change, but they are always characteristic and always remain the same for each element. In this case here, you can do the analysis either using this line or this line. And in most times, you can do the analysis using both lines. So you have a better restriction of your result. You have an example about pixel. I don't really care about pixel, believe me. Okay, microbeams. As you will see, the big thing that you gain with microbeams is what we call elemental mapping. What is a microbeam? So you have your normal beam. You have here three, two or three quadruples focusing your beam down to one to two micrometers, depending on your setup. You can, as we said, analyze small samples, less than a centimeter. But here there is another trick here. You have an electromagnetic steerer. So here you have another device that can steer you your beam. So your beam is focused. It's down, let's say... You can play with that. It's down like that. Okay, don't see me traveling. And with this steerer over here, you can do this thing. You can go back and forth, back and forth. Also, because in this steerer you have two steers like that, you can go down. So what you can do, you can do that thing over here. You can scan. You can measure a square or whatever you want. The other thing is that this device over here, this steerer, is synchronized with your acquisition. This means that when you take information from this place, also the position is recorded. Here the same, here the same, here the same, here the same. And how this thing is good is good because if you want to analyze something like that, this is what you take. We analyze this artifact over here by scanning. And here you can see with PIXE always what is the mapping of each element. For example, here we are looking at aluminum. Okay, so you can see that in this place over here you have no aluminum. Here you have no aluminum. While you have aluminum over here. On the other hand, if you look over here, which is copper, you will see that I have copper in the middle here. While I don't have copper here and here, or if you want to see it in another mapping, which is more impressive, is this thing over here. It's the analysis of Lapis lazuli. Lapis lazuli, it's semi-valuable, I believe, rock, if you can call diamonds rocks. Okay. And you can see here, sodium, magnesium, maps for aluminum, silicon. For example, I told you in the beginning that you can't extract directly chemical information. But here you can see, for example, wherever I have calcium, I miss silicon. You can see wherever I have silicon, I have also aluminum. You can see wherever I have sulfur, I have calcium and I have some aluminum. So here you can see in various spots of your sample, of your artifact, what's happening. And this is something more impressive. Here is a painting, sorry. And you can see what colors, what let's say elements the painter used in order to make the paints for this painting. You can see, for example, barium, where he used barium. Remember that every element is corresponds or is attributed to a color. For example, when we are talking about lead white, lead white is called lead white because it has lead. When you are talking, for example, we are talking about cobalt blue. Cobalt blue had cobalt. So here we can understand, for example, that he used cobalt blue for the eyes. But the main reason for this transparency is this over here. This is a very nice paper from Tomaka Ligaro. Pixel analysis is, again, worth the risk. What you see here is the analysis from XRF. And what you see here is the analysis from Pixe. As you can see, Pixe has more accuracy. You can see things that you can't see with XRF. For example, phosphorus here with XRF, you don't see anything. Cobalt, you don't see anything while here. You see cobalt. But the real question is the following. If somebody comes and asks you, I have this painting or I have this artifact, and I want to see where is Barium. Barium, you can see it easily with XRF. You don't need to do iron beam analysis. If with XRF, with some simple technique, you can give the answer, then tell the guy or the lady to use this simple technique. There is no reason for anybody to kill itself just to use iron beam analysis techniques. Because if we are talking for paintings, for a painting to come from a museum to your laboratory, it's a pain in the neck. While with XRF it's portable, you have some small pistol, you go over there in the museum for half an hour. You just hit your painting and you have the result you want. So just keep in mind iron beam analysis techniques are special techniques, but they take time and it's good to be used only if the information you are going to take is greater, is more important than the information that you can take from a simple technique. If it's not, use a simple technique. Make life easier for everybody. But that XRF was made with a micro X-ray... XRF, yes. Micro XRF. It's not a pistol. Okay, it's not a pistol. It's a special setup. If you look at that, they have a very small X-ray source collimated and the whole system that also scans. Okay, it's not so simple. It's not just a pistol, just going like that. With external microbeam. Okay, and they still have a... Yeah, it's external microbeam because of course when you're using your microbeam and going through the window, this gives you some struggling. So your beam opens a little, but instead let's say of two microbeams, sorry, two micrometers, you go to 15. It's again a microbeam, 15. But instead that the whole system moves to scan, right? I mean, isn't it better to... Depends on the sample. Depends on the sample. When you have a big painting like that, so the painting was that, first of all, as we're talking about cultural heritage, nobody wants you to touch it. Okay, this is the first restriction. Don't touch it, okay? So for these reasons it's better to have a head moving with the detector than the sample. And also this thing was, when it was made, was also made for monuments. Okay, or for statues. So there when you have a bronze statue, it's easier. To move like that. If it's not yes, you can do that. You can do that. If we are talking about XRF, okay? Or PIXE, the good thing is that the precision you have by moving your beam is much greater than the precision a stepping motor can give you. Nanometer is their beam. No, no, no, they move it without a real precision. The sample, and they have also... I know that they have sub-microbeams. I know they have developed, first they developed sub-micro-meter, let's say the first nano-beam. It's not microbeam. Right now they claim 30 nanometers. The roll is much slower if you hold the sample. Yes. This guy from Singapore is not right. What's his name? Frank Vat. Frank Vat is from Singapore. He's retired from Singapore. In this case, this Toma Caligaro is from Luger. And in Luger they have the best external microbeam. And as far as I know, they have this system that moves the whole XRF. This is what I saw. Exactly from that reason. This painting that costs more than human life. Come on, no more than human life. You're exaggerating. No, they're real. You said the team site, what is the team site? Nanometer. They claim. And the question is what is the current? And also the thing is, as always, how small you need it? What is the precision? For example, if you can do your job with a 1mm beam, do it with 1mm. If you need really precision and you want to... Okay, just finish my sentence. If you want two micrometers or three micrometers, then, yes, use a microbeam. If you really, for example, if I remember well, they were working with cells, not human, organic cells. So there you need less than one micrometer. So, yes, there, nanometer is what you need in order to see what's happening in a cell. But if you don't need it, don't do it. This is always my way of thinking. So, before going into πίγε, partly we'll use gamma ray emission. Let's do the break, because not cool. No, no, it is just to... And let's discuss how to organize. To organize, yes. Is there a way of... Okay, you all can find the... And it was also...