James Smallcombe: There we go.
James Smallcombe: OK. So again, so we're very pleased to have similar here. So, a bit of a background where I've asked him for. So he took his bachelor's, master's and PhD all cooler than wait till the PhD under deep and people
James Smallcombe: That and after that he was served as a fellow for two years. And very recently just last month. He's returned back to Cleveland, which is where he is right now deliver the seminar for us. And so
James Smallcombe: I think that's effective, thank you very much for joining us. And I'm going to hand over now to see
simon.sels@cern.ch: Thank you very much. James
simon.sels@cern.ch: For the very kind introduction and thank you very much everyone
simon.sels@cern.ch: For Joining these UK lockdown seminars. It's been a pleasure. It is a pleasure to actually present to you the topic of my recent work and
simon.sels@cern.ch: When I started making this presentation I initially insisted or initially thought I would only talk to you, miracles that is older.
simon.sels@cern.ch: But as I was adding more and more to the talk I actually added more and more. And in the end, I think I came to the conclusion that it was better to give a sort of overview talk and
simon.sels@cern.ch: Use three examples of my own recent work to give an overview of some developments of laser spectroscopy for radio your radioactive isotopes in general.
simon.sels@cern.ch: So, how to outline of my presentation will actually look like is the following. So our first give a broad overview of the why and how of laser spectroscopy for nuclear physics in general.
simon.sels@cern.ch: And I'll describe some techniques that are used for laser spectroscopy that are currently state of the art and our focus on three examples of these techniques. So I will talk more, more specifically about laser spectroscopy using the in source technique of
simon.sels@cern.ch: 177 228 mercury, I will talk about some in gas jet laser spectroscopy work we've been doing. And then recently over the last two and a half years while I was at certain I was working on.
simon.sels@cern.ch: Called linear laser spectroscopy at miracles and I'll show you some some very quick results on magnesium and calcium isotopes. And I'd like to end with a short introduction in what the future will bring according to me for laser spectroscopy of radioactive isotopes.
simon.sels@cern.ch: So let's dive in.
simon.sels@cern.ch: Laser spectroscopy for nuclear physics is
simon.sels@cern.ch: A very useful tool to actually described
simon.sels@cern.ch: Stuff like charger a di or magnetic moment or in general ground states in America states of nuclei, but it fits actually in the broader scope of nuclear physics in a sense that
simon.sels@cern.ch: It helps in in the understanding of the atomic nuclear saying in general, which I think everyone here will agree with me. It's not an easy task. It's
simon.sels@cern.ch: Trying to solve the nuclear quantum anybody problem in which the interactions between the nucleus are not
simon.sels@cern.ch: Fully known yet and in such I think almost all of the nuclear theories that are used to describe the atomic nucleus across different regions of the nuclear chart.
simon.sels@cern.ch: Need input from experiments to actually
simon.sels@cern.ch: Develop themselves and in order to understand the atomic nucleus in general, which is the goal that I think most of us are working towards. And in general, we tend to say that we need this.
simon.sels@cern.ch: this feedback loop between theory and experiments where theory predicts the outcome of experiments and then vice versa experiments are necessary to benchmarking invalidate the theories that are used.
simon.sels@cern.ch: And as such, we as a field in nuclear physics advancing in general. Now the nucleus.
simon.sels@cern.ch: Is of course at the heart of the the item.
simon.sels@cern.ch: Itself consists of neutrons and protons, which themselves consistent again of corpse quarks and and
simon.sels@cern.ch: Hell are held together by strong force, for instance, and sometimes I have the feeling I often get the feeling that the smaller parts like how quarks and
simon.sels@cern.ch: Such are described by the
simon.sels@cern.ch: By the standard model for instance is much better understood and then how to some of the phenomenal logical models that are used for the nucleus, actually.
simon.sels@cern.ch: Come to come to be. So in a sense, the atomic nucleus is at the center of this this letter from from downwards quark and the quarks and gluons upward city atoms and and while the the world that we perceive of the day. So then stomach nuclear physics in general.
simon.sels@cern.ch: Connects to a lot of different types of experiments being
simon.sels@cern.ch: Beyond standard model of physics astrophysics neutrino or dark matter physics and whatnot but
simon.sels@cern.ch: How would. How does laser spectroscopy coming to this thing.
simon.sels@cern.ch: Well experiments, as I said are necessary to benchmark and validate to reason that are used to describe the nucleus. And there's many, many, many different types of experiments too much to actually name here. Think of
simon.sels@cern.ch: Decay spectroscopy experiments or reaction experiments or or whatnot. But today I will only talk about laser spectroscopy and in
simon.sels@cern.ch: In that sense, we call it atomic spectroscopy or optical spectroscopy and laser spectroscopy provides nuclear physics with model independent measures of the nuclear spin the electromagnetic moments in the charge Ray di of
simon.sels@cern.ch: Radioactive isotopes or eyes and ears are long lift it.
simon.sels@cern.ch: And if you would look at how the optical spectroscopy hasn't been performed across the nuclear chart, then this is what you would see you would see that there's
simon.sels@cern.ch: A large range of accessible nuclei, which are which already have been studied using optical spectroscopy that are indicated in red and in there's
simon.sels@cern.ch: Indicated in grey. A lot of zones as well which haven't been studied using optical spectroscopy. So we see some clear gaps here in the heavy element region in some of the refractory regions of
simon.sels@cern.ch: The nuclear charged, as well as, as well as on the proton and neutron drip lines, for instance.
simon.sels@cern.ch: But laser spectroscopy has been key in in describing some of the
simon.sels@cern.ch: Some of them very interesting regions of nuclear chart like when I pick out some someone over here. It's for instance the
simon.sels@cern.ch: Shape coexistence in lead region, for instance, has been has been studied using laser spectroscopy and using laser spectroscopy. People want to bridge the gap towards the island of stability in vice versa. The island of inversion on this side of the nuclear chart or if we go lower even
simon.sels@cern.ch: To Halo nuclei and whatnot. So it's been
simon.sels@cern.ch: Key in describing many, many, or at least not describing with helping in the description of many of these interesting phenomena which the nuclear chart is riddled off.
simon.sels@cern.ch: And
simon.sels@cern.ch: So how does laser spectroscopy work for nuclear physics. Well, there's many different techniques and I'll go into them.
simon.sels@cern.ch: One by one in the near future or in the next following slides.
simon.sels@cern.ch: But the principle of laser spectroscopy is basically the same for all of these techniques so you, you have a nucleus that is at the heart of the atom and the electron transitions of the atom or an iron, for instance.
simon.sels@cern.ch: These are influenced by the nuclear structure themselves. So what we do is we actually probe the electronic transitions using lasers or optical
simon.sels@cern.ch: Spectroscopy. In order to reduce the nuclear structure from the nucleus that is at the heart of the atom.
simon.sels@cern.ch: So if we take, for instance, this electronic transition here.
simon.sels@cern.ch: For the STP transition in this case.
simon.sels@cern.ch: And we take this as an example to explain some of the shifts and and how we actually do the nuclear destruction information from this
simon.sels@cern.ch: Um, I can show you by by example and the right here. So if we have
simon.sels@cern.ch: A nucleus. A and another nucleus. A prime another isotope of the same same element, then
simon.sels@cern.ch: The electrons will will have a shift in their transition energy and this is what we call the isotopes shift and isotope shift is
simon.sels@cern.ch: The shift in energy levels for the electronic transitions. Then for the different nuclei, the different isotopes.
simon.sels@cern.ch: And the isotope shift itself skin itself can be
simon.sels@cern.ch: Broken up into my shift on the left hand side here and the field shift on the right hand side and the field shift is the one that's actually sensitive to the difference in
simon.sels@cern.ch: Me square chart radius which I indicated by this red circle over here. So if we measure the isotope, for instance, we can actually do something from the main square charts radius on the right hand side over here.
simon.sels@cern.ch: And more generally, if we do laser spectroscopy for long chain of isotopes, as has been indicated on this plot here in the lead region where I've plotted the church re di
simon.sels@cern.ch: That are deduce from the isotope shift. Well, you can actually see general trends that are also visible in different types of experiments, like for instance when you would look at the e to
simon.sels@cern.ch: Excitation energies, for instance, but
simon.sels@cern.ch: What, what is it clear here for instances at the n equals 126 shell closure, you have this distinct upwards.
simon.sels@cern.ch: Because it really deviate from the expected trend over here.
simon.sels@cern.ch: And this is n equals 100 for Michelle and as you approach the Michelle, for instance, you can see that some of these lines actually start deviating from their expect sort of trending behavior and
simon.sels@cern.ch: This is what what you would indicate, for instance, as an onset of deformation, more precisely in the region over here.
simon.sels@cern.ch: Some, some more funky stuff is actually happening so
simon.sels@cern.ch: By just looking at the general trends of different long chains of isotopes. You can get a lot of information from the isotope shift in the church radius itself already
simon.sels@cern.ch: On the other hand, except for the isotope shift itself. We also have another interaction. And that's actually the hyper find interaction and the hyper finding direction, you can expand in the dipole dipole
simon.sels@cern.ch: Interaction and then actually the following turns I dropped out.
simon.sels@cern.ch: But the formula here is not really important here. What is important is actually that the high profile shift.
simon.sels@cern.ch: Which actually splits these electronic levels in into sub levels that are indicated now. Bye bye. New quantum numbers. F.
simon.sels@cern.ch: Well, the splitting of these levels is indicated by the
simon.sels@cern.ch: The hyper find a in the hyper find the parameters as indicated here and I provide a and b parameters themselves are earning to the magnetic moment and new political moment after nucleus.
simon.sels@cern.ch: So if you can actually measure we can change the frequency of our laser and we can measure these transitions over here and the transition energies from the spectra over here, we can deduce the magnetic moments in moments.
simon.sels@cern.ch: Of a nucleus.
simon.sels@cern.ch: So to summarize for laser spectroscopy. What we do is we measure the isotope in Isaiah shifts and the hyper find splitting.
simon.sels@cern.ch: From these we did do is in a mole independent with some information about the size the quarter pole and dipole moment the nuclear spin, for instance.
simon.sels@cern.ch: And this gives us information about both shapes and deformation parameters of different nuclei, but also about single particle configurations. So in general, it's actually a very powerful tool to describe ground state and longest isometric states in nuclei.
simon.sels@cern.ch: Now,
simon.sels@cern.ch: That's how laser spectroscopy works.
simon.sels@cern.ch: Or at least in a nutshell.
simon.sels@cern.ch: But some of the well all of the experiments that I will describe here have been done at radioactive iodine being facilities and these
simon.sels@cern.ch: Really active I mean facilities they they post some extra challenges that the laser spectroscopy techniques have to fulfill. So if we work with exotic nuclei, for instance, and we know that
simon.sels@cern.ch: We have or we can have work we sometimes have to work with a very low production yield sometimes less than a nine per second. And these ions are produced online.
simon.sels@cern.ch: They work with very short half life.
simon.sels@cern.ch: For instance, the ISO method, we can work with isotopes down to a millisecond, for instance.
simon.sels@cern.ch: However, we work with these exotic nuclear will often have to deal with a lot of contamination are being set of isotopes that
simon.sels@cern.ch: Are sometimes orders of magnitude more produced and isotope, you want to study ourselves. So the laser spectroscopy techniques. They have to be efficient. They have to be fast and they have to be selective
simon.sels@cern.ch: So that's basically the requirement of all laser spectroscopy techniques Riddick I'm beams and if we, for instance, take as an example for radioactive iodine being facilities, all of which is the one or the one facility that I've been working at for the last few years and
simon.sels@cern.ch: If you look at the result of being delivery, for instance, we have up to 1000 different isotopes that have been produced it seven of 75 different elements with very large half-life ranges and very large production ranges as well.
simon.sels@cern.ch: And the technique of laser spectroscopy. That is actually shown in here, I will come come back to the few slides from them, but the general production mechanism of redemptive I'm beams, for instance, at these old and in this case is by
simon.sels@cern.ch: Impinging a
simon.sels@cern.ch: Beam first beam on the second target and is all it's happening. It happens to be that we impinge proton beam that's indicated in red here on one of the to target stations and in these targets stations.
simon.sels@cern.ch: We had, for instance of a target that can be built up of uranium, for instance, and the interaction of the protons with uranium via efficient or fragmentation or escalation.
simon.sels@cern.ch: Reaction, and these these fragments these directions are all happening in the target and they're producing a cocktail of many, many, many different types of isotopes, and then
simon.sels@cern.ch: These isotopes, or at least some of the isotopes are ionized and then extract it and send through separate your magnet before they can actually be sent to one of the
simon.sels@cern.ch: One of the experiments that are at is all in, in this case in the experimental help. And this is where, for instance, would would place some of our experimental equipment for laser spectroscopy.
simon.sels@cern.ch: And this is just a picture of what it looks like.
simon.sels@cern.ch: Now, if you look at different types of laser spectroscopy and react defying the facilities.
simon.sels@cern.ch: This can be grouped in roughly, I would say two different categories in in the one on one hand side you have the in source laser spectroscopy.
simon.sels@cern.ch: That group of techniques and, on the other hand side you have calling your laser spectroscopy. Now these are by far the workhorses that have been used in laser spectroscopy predictive isotopes so far now.
simon.sels@cern.ch: In general, and I can be a bit blunt here or I will be a bit
simon.sels@cern.ch: Maybe
simon.sels@cern.ch: Cutting short, some of the details, but you could say that the in source type of experiments are very sensitive they they can go down to
simon.sels@cern.ch: production rates have less than one, nine per second routinely but they suffer or they are characterized by having a very
simon.sels@cern.ch: Bad resolution in the order of a few gigahertz. On the other hand side. If you look at the calendar and types of laser spectroscopy, then you could say that these types of
simon.sels@cern.ch: Neither spectroscopy are
simon.sels@cern.ch: Much more precise, but they suffer from not being able to go down in production rate as low as the in source spectroscopy techniques do
simon.sels@cern.ch: Now,
simon.sels@cern.ch: I'd like to continue by showing you three examples of techniques, two of which are in source techniques and one example of a linear technique and
simon.sels@cern.ch: Then I'll go on and actually show you three examples of
simon.sels@cern.ch: Or one example of each of these three techniques and if you happen to those off at one point or the other because it's a online seminar, I wouldn't blame you. Absolutely.
simon.sels@cern.ch: And you can always pick in or you can always stop backing and when I moved back to one of the other example. So you will be able to follow from that point on, again,
simon.sels@cern.ch: So let's start with, for instance, hot cavity laser eye in nine ization spectroscopy.
simon.sels@cern.ch: Which is an in source technique.
simon.sels@cern.ch: In this technique we have protons that impinge on
simon.sels@cern.ch: Heavy target, like for instance or uranium target and you create the isotope, you want to study in, in this case it's it's shown for a city.
simon.sels@cern.ch: But it can be used for instance for mercury, lead or whatever you want to study in that, in that sense now.
simon.sels@cern.ch: This target is held at a very high temperature and the isotopes that you want to study or the isotopes that are creating these matrix are diffusing out and
simon.sels@cern.ch: They come into the hot cavity I in source zone. And in this hot cavity zone. They are overlapped with
simon.sels@cern.ch: One or more laser beams that actually resin redundantly ionized isotope, you want to study and once it's ionized you can extract it using an extractor electrodes and accelerate it to a few 10s of ke VI and
simon.sels@cern.ch: Dipole separated with a dipole magnitude respective masses and then send it to a detection station you wherever you want to send it
simon.sels@cern.ch: Now, this technique has some disadvantages, for instance, it's very difficult to actually
simon.sels@cern.ch: Create your a factory element beams.
simon.sels@cern.ch: The half life cannot go down to a millisecond or less, but it's not too bad. In that sense,
simon.sels@cern.ch: Sensitivities very good that the resolution on the other hand is gigahertz. And it's purely or almost purely Doppler related because you have such a high temperature. In this sense, all
simon.sels@cern.ch: The islands that start out from here. They have a very high energy spread as an as an ensemble itself. And this high energy spread actually results also in a high Doppler spread so
simon.sels@cern.ch: All of the INS here. They have a random velocity in one direction or the other. So you can see where you can visualize this. Like if all of these ions would actually see a different laser frequency impinging on themselves. So if you have a large energy spread and
simon.sels@cern.ch: In this case, it also results to a large philosophy spread of your ions and you will have a bad resolution.
simon.sels@cern.ch: The second technique that I i wanted to quickly introduce you to is gas cell laser spectroscopy, which is also an insert technique and
simon.sels@cern.ch: In this technique you actually work with a gospel which is, in a sense, not safe strange if you look at the name
simon.sels@cern.ch: And in the gospel, for instance, you, you can have a thing target and an iron beam coming from one place or the other can be a cyclotron in the example that I will use
simon.sels@cern.ch: will impinge on this target and the reaction products will actually a fusing to the to the volume here and they will be stopped and neutralize thing is region of gas.
simon.sels@cern.ch: Which is at around 300 or so maybe bar 500 million bar that that order of magnitude. So they will be stopped and they will be neutralizing the gas flow which which comes from the gas in Latin actually moves its way down all the way to the exit of of the gospel.
simon.sels@cern.ch: And the this discuss flow carries the isotopes that were created and the ions that are then created will also well not is the
simon.sels@cern.ch: Reaction products are created tool at one point. Follow through this, the small channel where the also the iron the lasers are overlapped with the
simon.sels@cern.ch: With the elements. And then the the ionized the species that you want. And once they are a nice, you can again extract them and send them through a massive breakthrough and whatever.
simon.sels@cern.ch: Now, in this sense, it's
simon.sels@cern.ch: It's less chemically restrictive in the sense that
simon.sels@cern.ch: You don't depend on anymore and the chemistry of evaporation for your isotopes to come out of a thick target and that actually opens up a wide range of elements that would be available on the other hand,
simon.sels@cern.ch: There's different timescales that come into play here because the half life is now did you have the isotopes, you can study is now depending also on the evacuation time of your cell and how much gas. So you have
simon.sels@cern.ch: The sensitivity of this technique is is very, very good as well. You can also reach very low iron yields, but the resolution is again quite poor as will be in KC mo site in source techniques and in here. It's actually both pressure
simon.sels@cern.ch: Is caused by pressure and temperature actually
simon.sels@cern.ch: In a gospel type of experiment and the resolution is in the again the the laser spectroscopy resolution.
simon.sels@cern.ch: Now the last technique that I want to introduce you to is cleaner laser spectroscopy and in cleaner laser spectroscopy. This is not an insert stick need
simon.sels@cern.ch: So you actually assume that an iron beam is already created at some source and this source location is not where you do the laser spectroscopy itself. You actually extract the beam in some way and you already start with
simon.sels@cern.ch: An MMA separated bunch or MMA separated continues be and in this case it's shown for instance.
simon.sels@cern.ch: For 30 kV but but what happens in cleaner laser spectroscopy is that you have this iron beam coming in and you overlap, your laser beam call linearly with the iron
simon.sels@cern.ch: And because you've accelerated your iron beam up to this order of magnitude of 30 killer electron volts, for instance, what happens is that the velocity spread goes as one over the square root of the energy of up so you can actually reduce the velocity spread
simon.sels@cern.ch: By accelerating your I envy and this is basically the crux or the heart of cleaner laser spectroscopy.
simon.sels@cern.ch: Because a reduced philosophy spread will also reduce her Doppler broadening and therefore you will have a very good resolution now the lasers.
simon.sels@cern.ch: That are overlapped with the iron beam or than in resonance with with ions in front of for instance.
simon.sels@cern.ch: Set a force multiplier tubes. So you excited atoms up to first excited state. For instance, and then they decay back down and you can measure the photons in Fortran multiplayer tube so
simon.sels@cern.ch: That's one type of laser laser spectroscopy. Another type could be that you actually add several other laser beams and
simon.sels@cern.ch: Yeah, at neutralize or over here. And then you could for instance reorganize but but the idea is the same. You, you could linearly
simon.sels@cern.ch: Overlap your laser beam with a fast iron bunch and therefore, we actually have a great resolution and the great resolution actually means that resolution, the orders of 10s of megahertz or which is often the case for stronger transitions which is corresponding to the natural line with
simon.sels@cern.ch: Of course its production dependent, but the sensitivity, although it's being good and being improved every year since it's being introduced, it's still not there yet to the 0.1 is per second that in source spectroscopy can actually do
simon.sels@cern.ch: So,
simon.sels@cern.ch: To conclude here. It's basically also. That's what I wanted to say is that the resolutions for the in source techniques or worse for the sensitivity is better and vice versa for cleaners.
simon.sels@cern.ch: Now the sensitivity of the cleaner spectroscopy has been increased by using, for instance, bunch beams in an RF Q cooler puncher, and by using resonance ionization spectroscopy. But if I found correct. I think still the
simon.sels@cern.ch: The best sensitivity that been obtained so far is in the order of 20 cents per second.
simon.sels@cern.ch: However, if I please all the techniques that I've just addressed to and
simon.sels@cern.ch: What I can say is that higher resolution usually suffers from low efficiency and vice versa. However, there's
simon.sels@cern.ch: A list of and it goes on. It's just a list that I came up with earlier today of techniques that are currently being developed or or have been developed in recent years.
simon.sels@cern.ch: For actually increasing the resolution for the source techniques which I which I grew up over here. Or, on the other hand, increase the sensitivity for
simon.sels@cern.ch: The good resolution technique of clean your laser spectroscopy, for instance, and two of the techniques that I will actually talk to you about later, is the industry spectroscopy technique and the miracles technique.
simon.sels@cern.ch: Let me check time now.
simon.sels@cern.ch: I actually had a full example prepared of the in source laser ionization spectroscopy technique on mercury and but actually I think due to time constraints, I will almost fully skip this one and I will only talk to you about
simon.sels@cern.ch: In gas jet laser spectroscopy and miracles type laser spectroscopy. So
simon.sels@cern.ch: I'm just gonna flash for your eyes what you could have seen if I if I were a veteran in time management.
simon.sels@cern.ch: And very sorry for that. If you have questions about this one minute of very fast slides skipping, please don't hesitate to ask me afterwards.
simon.sels@cern.ch: So,
simon.sels@cern.ch: What I wanted to talk to you about further is that in ghosted laser annotation spectroscopy technique and into miracles type of technique.
simon.sels@cern.ch: So I told you about the Inca sell laser spectroscopy technique where actually we have a poor resolution because of the pressure in the temperature into gospel
simon.sels@cern.ch: Now the idea behind industry at least organization spectroscopy is that if you add a deal of owners will tear gas so
simon.sels@cern.ch: You can actually create supersonic gas jets. So the pressure difference between the volume over here and in the background pressuring vacuum chamber over here.
simon.sels@cern.ch: Creates the supersonic jet and the supersonic jet is such that it has a very reduced temperature. So by
simon.sels@cern.ch: Using different Mark numbers of delaval nosal you can actually reduce your temperature from room temperature for instance 300 Kelvin, all the way down to only, only a few Kelvin. If you go high enough.
simon.sels@cern.ch: So by doing so, you reduce it on your temperature will actually also the density and, as such, you can go very, very high resolution and has been proven in the last experiment that we were able to do with this technique online I show you here and
simon.sels@cern.ch: For acting so in global enough we first did an experiment on a continuum, where we ionized active me in a gas cell. And we looked at the hyper find spectrum and then
simon.sels@cern.ch: We came back to it after we installed a delaval nozzle and we actually were able to reduce the resolution of this this measurement with a few orders of magnitude and
simon.sels@cern.ch: Now, I must say that this was a very crude experiment, this will really proof of principle that the devil knows or wasn't characterized or lasers. We're also brought in from a different lab and it was all kind of
simon.sels@cern.ch: How you would say very fastly done but actually proved it proves that technique very nicely. Now, we were able to actually
simon.sels@cern.ch: Continue with the technique and developed a technique in
simon.sels@cern.ch: In in love and offline in how we develop the technique and live and offline is we we add we built knows laboratories. We built a laser laboratory in a jet little bar Terry and in the jetlag oratory, what we do is
simon.sels@cern.ch: We have a gas cell and a gas jet and we overlapped lasers with the gas chat and either we studied the fluorescence of the gas chat with a camera or we study the ionization into ghosted by sending it through a mass separator on the high voltage platform and detecting
simon.sels@cern.ch: On an MCP or or whatever type of technique you want to use. But if you, for instance, look at the Jet visualization or the jet formation in the industry technique you can see that actually the
simon.sels@cern.ch: You can have jets that are very
simon.sels@cern.ch: Bad for these are spectroscopy, because they are under expanded or overextended, because what you actually want is a jet that that looks like this. In order to have a have a good resolution.
simon.sels@cern.ch: And that's what's been going on over the last few years and Caleb and where we have been correct rising these types of jets and I've been developing this technique in general.
simon.sels@cern.ch: Now,
simon.sels@cern.ch: A topic that we've been working on the 11 we started working on 11 is, for instance, that the 229 thorium.
simon.sels@cern.ch: Is America. This is America is famous for being a potential candidate of using a nuclear clock.
simon.sels@cern.ch: Because it has an low lying ice and married. It's actually reachable using laser laser line with so or laser frequencies optical frequencies and
simon.sels@cern.ch: By doing so, you could actually excited nucleus directly, for instance, then you could build a nuclear clock that's set to be able to
simon.sels@cern.ch: Perform better than then currently atomic clocks and that's it. We're doing it live. And now it's actually we're trying to produce a pure beam of a pure iron beam of of the tourism is Amir
simon.sels@cern.ch: And that's what we've been working on for the last few years, and how we will do it is
simon.sels@cern.ch: By ionizing selectively only the ice Amir the two to 9am and if you look at the how the frequency spectrum would look like. You can put your laser, for instance, on this transition only and then you can only ionized this peak.
simon.sels@cern.ch: Then you would end up with only a pure beam of soaring to tonight.
simon.sels@cern.ch: But in the, in the future, actually plan to go to
simon.sels@cern.ch: Daniel, for instance, with this technique at the sq facility where we will be able to probe the new isotopes in the heavy element region or, for instance, n equals that region over here.
simon.sels@cern.ch: And here's a visitor ization of
simon.sels@cern.ch: What the elements would be that that coming to reach for actually the industry laser ionization technique. So that's a an intriguing future that's coming up.
simon.sels@cern.ch: And then as the last example I wanted to talk to you about last two years, or I've been doing in the last few years at look at CERN.
simon.sels@cern.ch: Is working on the miracles project. And that's a whole new type of calendar laser spectroscopy, where we perform laser spectroscopy in multi reflection time of flight device.
simon.sels@cern.ch: Now we're multi reflection time of flight device is actually an iron trap that's mostly used for mass measurements I sell trip, for instance, has marked off for mass measurements and we've actually
simon.sels@cern.ch: refurbished an old Christ or a marked off, which consists of two electrostatic mirrors one over here and in one over here.
simon.sels@cern.ch: And we trap an iron bunch in the Mr tough such that it bounces back and forth for several thousands of times in the Emirates off. And when we over that are laser
simon.sels@cern.ch: What would happen in normal clean your leaders spectroscopy that you would only excite your items once or your iron bunch once in miracles type at calling your laser spectroscopy. When we can probe the same iron bunch for thousands and thousands of time and that's
simon.sels@cern.ch: What we've been doing in a proof of principle experiment in certain over the last few years, and I can show you some of the
simon.sels@cern.ch: Some, some other results quickly now. So we added the laser to the immortal for optical excitation and at 14 multiplier to for detection of fluorescent light.
simon.sels@cern.ch: And because we can increase the i in observation time. We can also gain a lot of several orders of magnitude insensitivity for linear laser spectroscopy.
simon.sels@cern.ch: And one of the experiments that we've put forward in the last month at a ITC for at is all the, for instance, it be would be to to study the cadmium isotopes, where the eclipse experiment which uses standard come in your laser spectroscopy was not able to go further than these.
simon.sels@cern.ch: Two isotopes on a neutron region on deficient side but using the miracles technique to actually want to push this this further out and go to for instance 98 Academy where we are only two protons away for hundred team or cross the n equals at to shock closure over here.
simon.sels@cern.ch: Currently, we have a proof of principle that's working. And actually, we're finalizing the work of the proof of principle, but we want in the future to build a 30 kilo electron volts Emirates of that.
simon.sels@cern.ch: That works with I inventions that have an energy of 30 kilo electron fault because it allows us to go and get the high result resolution in optical spectroscopy that we're used to from cleaner laser spectroscopy.
simon.sels@cern.ch: This is just a picture of our of our multi reflection time of flight device itself and
simon.sels@cern.ch: And this is what a photo multiplier to boot. See if we have a nine bunch that passes one time or then several times after that.
simon.sels@cern.ch: And as you can see, I'm not lying. When I say it's a proof of principle technique if you, if you look at how the cabling is being done here and how how everything changes for actually from week to week, month to month
simon.sels@cern.ch: So at miracles. We want to increase the sensitivity by by probing the iron bunch that you normally see ones in conventional laser spectroscopy over multiple times. And we did this using magnesium in the first case.
simon.sels@cern.ch: In this graph, you see seven or eight revolutions are you see seven or eight eight peaks extra with compared to the normally one peak, you would see
simon.sels@cern.ch: Now this is
simon.sels@cern.ch: She do a longer measurement. For instance, you see all these types of peaks. When we inject our iron luncheon in Mr tough and when we each act it which is clearly seen by the photons that are highly reduced. But if you zoom in on a certain region, you see that every
simon.sels@cern.ch: Passing of the ions in front of the photo multiplayer tubes give you this type of enhance or this type of signal and then you can enhance your total signal by just summing up all of these different different people.
simon.sels@cern.ch: So at CERN. For instance, if you work with a protocols it arrives at every 1.2 seconds and you get about half of the production process. So you say that every 2.4 seconds you receive a proton pulse.
simon.sels@cern.ch: What you get from normally 5000 bunches from his older which takes you.
simon.sels@cern.ch: 12,000 seconds, you can actually now measuring in less than 50 milliseconds, because you you actually probe the the iron bunch 5000 times in English in 15 minutes away.
simon.sels@cern.ch: So what it would look like is that if you
simon.sels@cern.ch: Change your laser frequency of our time. That is that you you build up this this resume spectrum over here. If you're off resonance. If you're on resonance and
simon.sels@cern.ch: If you're going into resonance. And if you're on resonance
simon.sels@cern.ch: And then you can get on different branches whenever an iron bunches in front of your photo multiplier acute, am I doing so you can actually
simon.sels@cern.ch: Measure the isotope shift. So the difference in frequency between 24 and 26 magnesium and in the same time. You can also do
simon.sels@cern.ch: mass measurements, because if you look at the time of flight spectrum of the iron bunch that are coming in that you see that
simon.sels@cern.ch: They are they're moving away from each other. And that's because of the master the flight difference or the time of flight difference between 26 and 24 magnesium due to their class. So this is basically also a mass measurement at the same time as well as a laser spectroscopy measurement
simon.sels@cern.ch: And
simon.sels@cern.ch: I'm not going to tell you more about calcium because I see that my time is already running out.
simon.sels@cern.ch: Just to tell you that, in principle, miracles only works or the only not only works but and would work best at a closed level system where you continuously reprogram reprogram but you can also close your atomic transition systems in different types of ways, and you can gain signals.
simon.sels@cern.ch: But as a conclusion I what I wanted to tell you with this presentation is that laser spectroscopy is an exciting tool for studying nuclear grounding isometric state properties.
simon.sels@cern.ch: And although the field is already decades old developments are still going strong today and are coming out, year by year, and the drive towards combining a high efficiency with a higher resolution laser spectroscopy technique is is still going on.
simon.sels@cern.ch: In this talk I focused on the different developments of interest yet and miracles type. These are spectroscopy and I showed you some of the advantages and some of the technical difficulties.
simon.sels@cern.ch: But in the near future I think we can expect from laser spectroscopy of radioactive isotopes that it will become
simon.sels@cern.ch: More precise more sensitive and definitely accessible to more species. So I would conclude by saying that there is very exciting times ahead for laser spectroscopy. Mr. Everyone
simon.sels@cern.ch: Wanting to go into laser spectroscopy general. So by that. I want to thank you for your attention and thank you all to all my collaborators, both at CERN enact it live and
James Smallcombe: Thank you very much. That's, you know. So you've been very diligent with your time keeping we've got plenty of time for questions that people want to ask about those
James Smallcombe: It's the was skipped over folks. Oh, yes. As I said at the start, it's good if you could go into the participants menu and use the raise hand button. If you've got a question or type in the chat. I see lots of digital clapping. We've got lots of happy viewers.
For digital
James Smallcombe: And got a question from Liam. Liam, please God.
Liam Gaffney: I say, Mom, thanks very much for the talk. And I just, just because you were speeding up a little bit. The end. Could you
Liam Gaffney: explain a bit more about how you can deal with contaminants in miracles, I guess you can separate them by mass. So if you have some beam that's kind of dominated by contamination. Is that possible.
simon.sels@cern.ch: Yes, absolutely. So
simon.sels@cern.ch: The
simon.sels@cern.ch: Multi reflection time of flight devices, actually a very sensitive device for for mass measurements, but what it does is it's actually
simon.sels@cern.ch: Separating the different isotope species by mass and this is actually able to also separate esoteric masses, in principle, only so even able to separate those two Barrick masses quite quite easily.
simon.sels@cern.ch: So she would have a contaminant beam of the same isotope or the same mass of the isotope, you want to study, you can inject it in your Mr tough and let it
simon.sels@cern.ch: Develop over this very short amount of time and because of the spatial separation. You can gauge on your photo multiplayer tube.
simon.sels@cern.ch: And only by by looking at the time when, when I in bunch that you expect or that you want to studies in front of the photo multiplayer to been as such, you can actually
simon.sels@cern.ch: Deal with the contamination on the laser spectroscopy side there is another way. What you can do as well as then
simon.sels@cern.ch: Once you have the separation. You can also apply kick for riches, so you can kick out the contamination actively and then remove it from the Emirates off.
simon.sels@cern.ch: And because the, the miracles technique is a non destructive technique, in principle, send the beam further on the words afterwards to different
simon.sels@cern.ch: Users of the facility. And that's what we're planning. It is all done as well where, for instance, the puma project or molecular beings types of project will be actually positioned after the miracles or behind a miracle set up for
simon.sels@cern.ch: For accepting very pure beams of radioactive isotopes.
Liam Gaffney: Great. Thanks so much.
simon.sels@cern.ch: Thanks me
James Smallcombe: We've got a question from jack jack
Jack Henderson: I think
Jack Henderson: I think probably two questions. And so it what what kind of wasn't clear and maybe it's not known yet is like, is there going to be
Jack Henderson: An overlap region for the different techniques like the insourcing the colon. Yeah. So it's the colon is still going to be less efficient than the in saucer is actually going to kind of all come together and so is everything going to be perfect.
simon.sels@cern.ch: Doubt, everything's going to be perfect. As of now, I don't think there will be one technique which will be the all encompassing technique. So in principle.
simon.sels@cern.ch: The basic technique or the basic ideas, even as soon as you add another element in between your source and yours experiment, you can add a loss factor. So cleaner laser spectroscopy, by definition are inherently will will always stay less sensitive than in Source Types of spectrum.
simon.sels@cern.ch: On the other hand, there, there has been some developments in the source type of
simon.sels@cern.ch: Techniques where you can you remove remove the Doppler shift or the Doppler shift the Doppler broadening
simon.sels@cern.ch: But these are techniques that are only sensitive are only applicable to a few types of candidates. So, there will not be in the near future technique that's available for all types of isotopes at
simon.sels@cern.ch: Both be sensitive and super good and resolution unfortunate, but that's the goal of course I've ever been doing these are spectroscopy.
Jack Henderson: And Quick, quick question. I was with the amount of the miracles method, how much I mean you're increasing your signal.
Jack Henderson: Yes, that you're, you're not doing a whole lot about background, but no, no.
simon.sels@cern.ch: No, so
simon.sels@cern.ch: Yes, there, there is a limit and the limit is, I think,
simon.sels@cern.ch: If I remember by heart. It's
simon.sels@cern.ch: Somewhere around
simon.sels@cern.ch: Order of magnitude of the half life of free isotope itself. And after that it's actually
simon.sels@cern.ch: You've lost to too much in a sense that you're adding background to your
simon.sels@cern.ch: Measurement as well. And then at that point it's better to just load in a new bunch and and measure that bunch, rather than
simon.sels@cern.ch: Trying to reprogram a decaying bench and adding background to the to the measurement every time as well.
Jack Henderson: Okay, cool.
James Smallcombe: Okay. Do we have any other questions.
James Smallcombe: I wonder to myself, which was a. So, the development of these these gas jacks.
James Smallcombe: Doesn't necessarily seem ideally within the
James Smallcombe: wheelhouse of a nuclear physicist. Have you developed interesting collaborations or has the group just been suddenly doing it all themselves.
simon.sels@cern.ch: Well, it's of course not stubbornly
simon.sels@cern.ch: Single group that that's been working on this, we have a rather large collaboration of people
simon.sels@cern.ch: That are doing calculations on on how to actually make these these nozzles that create the jets, for instance, to I'm thinking of the KPI which is or I'm not sure if I'm using the right abbreviation. But there's a group in Brussels, for instance. That's excellent. The good at.
simon.sels@cern.ch: calculating these these jets. And then we also have a lot of help, of course, from
simon.sels@cern.ch: The Kenyan people and we have a lot of internal discussions with the vascular wherever and this is not, this doesn't play in the 11 field alone. Of course, I think most of the developments that are happening in nuclear physics are, in general, a very
simon.sels@cern.ch: Broad overlap of different groups from from around the world. And that's some different here.
James Smallcombe: I'm good question from Andrew. Go ahead, please. Andre
Yes.
simon.sels@cern.ch: I think
AndreiAndreyev: See, what can you hear me.
simon.sels@cern.ch: Yes, I can hear you fine.
AndreiAndreyev: Nice talk, but I have one commission to qualify. Maybe it's very nice one. So inside them on top of it and some woman was on the left hand side was on the right hand side.
simon.sels@cern.ch: Yes.
AndreiAndreyev: So basically when you create kind of Doppler shift policy for negative direction.
simon.sels@cern.ch: Yes, you do.
AndreiAndreyev: Purpose to your laser. So do you do your liaison one kind of one half of fine so what what is it
simon.sels@cern.ch: Exactly. So as of now, we've only used a single laser input perhaps is actually what I skipped over
simon.sels@cern.ch: So I have some slides on this. So if you see the slide over here you have a laser beam. Let's go in this direction.
simon.sels@cern.ch: And you have an when I in bunches moving in the other direction, you will see a blue shift or redshift, depending on what weights moving now.
simon.sels@cern.ch: The Doppler shift between an iron bunch moving towards and away from the laser beam is by far away too much to excite with
simon.sels@cern.ch: With a single laser. So what you can do is you can actually send your laser from both sides. So you can send it one way and then second half of the laser power. The other direction.
simon.sels@cern.ch: Or what we've also been doing is we've actually been doing container and antique linear laser spectroscopy. At the same time, so right when you inject to laser beams that are shifted
simon.sels@cern.ch: By different frequency and the frequency shift of the laser beam, you can see over here. And what happens then is that
simon.sels@cern.ch: Well, it's not feasible over here.
simon.sels@cern.ch: Well, what happens then is that you actually double the amount of peaks. You see, because in
simon.sels@cern.ch: All in this picture that I showed you, you can only see the peaks of the iron bunch of these moving away from you.
simon.sels@cern.ch: But if you add this laser that that also has an EIN bunch that's being excited that when it's coming towards you, then you add
simon.sels@cern.ch: Not only to the statistics with actually also it removes a certain voltage uncertainty and it has all kinds of different benefits, but you're completely right. When you're seeing that
simon.sels@cern.ch: It would only with one laser be excited in a single direction. Yes.
Thank you.
AndreiAndreyev: Okay.
James Smallcombe: Do we have any other questions.
James Smallcombe: I do also say at this point that if any reason you can't use the raise hand button. I invite you to just unmute yourself and go ahead with your question.
Don't see anything in chat.
James Smallcombe: So I think that's all we have from the questions so little bit there and say, once again, thank you very much for giving a great talk, particularly at such short notice.
simon.sels@cern.ch: No worries. Thank you very much for having me was a great pleasure and
James Smallcombe: Thank you all for coming and paying attention and do please come back and join us again.
James Smallcombe: Next week, same time 3pm.
James Smallcombe: BST. It's the last BST seminar before daylight savings.
James Smallcombe: Where next week we'll be hearing from Mary or comments Ramos of T Darmstadt, so please do come and join us again next week.
James Smallcombe: And have a good week. Bye for now.
simon.sels@cern.ch: Bye, everyone. Thanks for joining.