 Hello everybody, and welcome to the Latin American Webinar of Physics. Today we are very happy because, I mean, we are in the webinar number 114 of this series of the Latin American Webinar of Physics that we started in 2015. So today we are going to have a very interesting talk by Professor Michele Doro. Michele Doro, he's an associate professor in the University of Padova, and before that he does postdoc in the Instituto Astrofísica de la Alte Energías in Barcelona, in the Autonomous University of Barcelona. And the talk that he will give us to us is the title is Trinity, a Compact Air Shower Detector for Ultra High Energy Screaming WTRINOS. So welcome Michele, and we are very happy to have you here in this low physics cycle. For all the people, just a little before, for all the people that are following us in the live YouTube streaming, you can ask questions to Michele in the chat so you can find it very easily. And Michele, welcome to the physics. Thank you, thank you Roberto. Thank you everybody for joining this, this meeting up today. And I want to thank Roberto for the invitation first and congratulate with you because as you said this is number 114 and I remember when I first read I learned the word webinar with you and with his effort that you did many years ago. And I was surprised back then how I mean to make speeches in remote but then it became reality so you have been a precursor of this kind of circulation of science. So really congratulations for keeping this for so long. Okay, thank you for the introduction. Shall I start with the presentation of the. Yeah, yeah. Sure. Okay, so let me share my screen should be coming. Okay, here. Great. Can you see it. Yes, perfectly. Okay, great. This, this presentation that I'm going to do today is about a novel design of a telescope to detect neutrinos. Okay. In the ultra energy range and this presentation was, I basically presented it few few weeks ago at a conference in Venice. So this presentation is on behalf of the Trinity collaboration. I have more information here there is a small web page. And I reported here if this if I can share the slides after all with you with the basic papers describing this, this new design of telescope. Hi, I want to underline that I work for the Department of the physical and astronomy here in Italy in Padua. It's where I'm talking now. And I'm also a member of the NFN that is the Institute of the National Institute of nuclear physics. You're welcome to come to Padua is a beautiful town and next year we will celebrate, we will be celebrating 800 years of our university. So let me make a spoiler already of what I will be gonna talk into you in the next minute, because you will model a shape what I want to say. So, we want to propose a telescope system composed of hating, hating similar telescopes. It will be so called air shower. Imagine chairing of telescopes. Okay, it's a technique that will briefly introduced it like CTA magic very test has. But it will be used to detect town neutrinos. Okay, and the technique is called earth skimming. Because the basic idea is depicted in the picture. So you have the earth profile here. You have the utrino, and especially a town neutrino. And the skimming is that you basically skim the surface of the earth. So there is a direction in which the neutrino crosses certain path in the ground within the ground. And there is a probability that it emerges as tau converts to tau and emerges. And if you have a towel, a charge particle in the atmosphere is where you have a shower of particle. And if you don't know, and from it you have a chairing of shower and you put your small telescopes here. And the main message is here is why this is a sensitive technique because we have. So to say the volume the fiducial volume is all this part of the atmosphere, which is hundreds of kilometer cubes. Okay, that's why you don't need such a big telescope. It's a collaboration. We are very few people. Okay, I will talk about that later. More mostly in the US, United Kingdom and Italy. We are in the design phase and we have applied for funding at the National Science Foundation in the US for one prototype telescope. And we have to be placed in the US, and we have located a frisco location called fiscal peak in Utah, and I will, I will talk about that later. This is the main reference that you can check really in which the instrument is pretty well defined. Okay, so that that was the spoiler, we know already what we will be talking about. So, what is the sensitivity? Okay, where where lies the sensitivity of this instrument. So you see this plot here in which you have the thickness of the ground crossed by the town at Reynolds. And here you have the probability of emergence as tau lepton. Okay, you need to have, you need to have some dense material in order to have a measurable probability for the town at Reno to convert to tau. Not only that but also from for the town to emerge from the ground and not to be absorbed within the ground. That's why you need to skim the earth. And as you see, the best, the best sensitivity region is with the thickness of the earth crust between say 10 and 100 kilometers here. Here you have a probability that is sizable 10% a little bit less. And I don't know if you can see here but it's the range of energy in which these probabilities maximum. And it's about 10 to the 1010 to the nine 10 to the 11 GB. This is what we call ultra high energy, ultra high energy range for the neutrinos. Okay. What is interesting is that, first of all, basically, only the probability of conversion into tau and the fact that the tau can can exit the exit the ground. Sorry, the lepton works only for the town at Reno so you cannot have the same situation with the electron neutrinos and the new neutrinos. Okay. The interaction, the probability of of emergence and conversion is different. And what is interesting also is that once you have the tau in the atmosphere, this is, this is a number of decay channels. Okay. I don't need to go into the details but I want to tell you that there are a lot of them as you see here that produce electromagnetic products. Take this one. Okay. For example, gammas, gammas, gammas. Of course, these are gammas at very high energies. And when you have a gamma in the atmosphere at very high energies, you will have the usual shower particle shower generation. So from one gamma, you will have a pay production from the pay production you have brainstorming gammas and so on. And then you have for some hundreds of meter or some kilometers, you have this multiplication of the particle shower, okay, until it dies out. Okay, so the particle shower is located here. But what is interesting is that from the electrons and positrons of the shower, what you can have, you have chairing confirmation, okay, because they are super luminal velocity in the atmosphere. And you have these lights that can now propagate further away. This is the technique of the IACTs such as HES, magic, as I was saying you, or veritas. Okay, so you put a telescope in this shadow here and you detect this chairing of light, which is kind of a blue ultraviolet light. You have a flash and you have your event. Okay, now this is, I don't know if you are familiar, but this is the picture of the two magic telescope. We are here in the Canary Island of La Palma. Beautiful, it's a place in which you can find many telescopes all very close one another and the observatory is called Rocca de los Muchachos. Okay, now these are two 17-meter diameters. Now maybe you don't appreciate, but the diameter of the telescope here is 17-meter. And these are, normally they are, during the day they are the point down, but during the night they point at the sky and do whatever they want to do with the gamma ray astronomy, okay. By chance, okay, there is no reason, but by chance we have, with magic, and I'm a member of magic, we have a window of visibility toward the ocean. Okay, we have the ocean in front of us, if we put the telescope pretty much down, so we have to point them slightly below the horizon, 92 degrees. We can see a pretty large fraction of the ocean, you see here the azimuth range, okay, we have kind of 60, 70 degrees and a window of 5, 10 degrees. That's the mountain behind us, okay. So basically, we can do gamma ray astronomy during the night, okay, but if we point the telescope toward the horizon, we can have sensitivity for these tau neutrinos, for we did with this earth scheming tau neutrinos. And in this paper that was published a few years ago by magic, but mainly by value, I want to mention that. We basically assessed all the steps toward the analysis of Cherenkov light in search for tau neutrinos, all the difficulties and the sensitivity. So what is the idea is that when you point the telescope in that direction, I don't know if you, oops, sorry, if you can see it. This is the telescope, the telescope here, what you have, it's a very nice situation in which you are kind of background free. Background free means that if you don't detect anything unless it is an neutrino and this happens because the background from say standard event is very, very far away, okay. It's very, very far away, the shower, the gamma shower, and so basically you don't see the light so far away, only the new ones can come there but you can easily discriminate. While your event, the event from the tau laptop is very close to the telescope. Okay, so the shower is very close and then the image is very strong. So basically we point the telescope, we wait and if we see an event it is very likely a town neutrino induced event. Okay, you see here the distance is 800 kilometers versus 50 kilometers. This is an example of the events, this is Monte Carlo, okay, we didn't detect it. So that's a typical mirror ring. So that's a background event for us and that's a typical tau laptop, one PV neutrino event in the telescope. You can see by eyes that it's impossible to not to discriminate them, okay. That's great, so we did this search. This is just another way to say that we can discriminate background from our signal so we can define the signal region in which we are looking and waiting for this rare event, which is important for the thing that I would like to say after. Magic is not the only one to my knowledge there is another instrument called the Ashera. It has an electrostatic lens and this is in Mauna, Lower Island, and it's also using the earth scheming technique facing now to another mountain, not to the sea, but to the Mauna Kea mountain. And there is a window here in which this is the profile of the mountain in which if you point the telescope here you have this right fraction of the earth crust for the probability to be maximum. Okay, this is circular so most of the field of view you don't need basically only this part is acted. But that's that's the instrument, okay. Now, the sensitivity with this kind of instrument is not that good. Okay, so look here. Oops. Yeah, I cut the energy. Okay. This could be, I don't know, now more than PV, anyhow, and this is the sensitivity limit. Okay, so now we have here ice cube sensitivity. This is an old plot for diffuse neutrino. We have here model of emission from a source. And here we have Auger, Auger limit. And you see here that magic with 30 hours, this is our limit. And this is an extrapolation are pretty far away from, you know, this part here in which we expect really the signals. This is the limit with Ashira is a little bit more sensitive but also perform with 1800 hours. You just put the telescope there and wait that long for for event. You see one event and that's that's their limit. We can do similar limits by assuming one source so you have diffuse neutrinos, but we know that we have, especially in these times now that we can have gamma rays associated to high energy neutrinos from specific source like blazer, for example. If you assume some fluxes, you can put limits to your target. Again, we are really, really far away with magic, but we proved this technique. Now, how do you improve on this? Okay, what do you need? Magic is a very big instrument. What do you need better? Okay, so, well, in order to make your telescope about this, of course you need the cosmic neutrino flux model. You need to model the interaction of the neutrinos in the earth, the emergence of the town neutrinos, and then you put a telescope there. But at the end, the system is pretty simple and all if you have a telescope that is in the in the shadow, say in the shadow here of the of the particle, you have this chance to detect to detect the neutrinos. And this is the basic idea. The only thing that you need is not a big telescope, not very large. You need a telescope with a wide field of view, okay? Because as I was saying, it is the atmosphere itself that is the volume, the sensitive volume of the instrument. You just need to have a telescope that is looking at a very big fraction of the atmosphere. So instead of having a circular telescope, what we were designing is this kind of instrument. I will come back to this, of course, that is kind of a section of a sphere, okay? It's larger than taller. It's kind of a rectangular section of a sphere. This is the structure. This is the camera. We'll get back to the technical performance. So the idea is now to go on top of a mountain, okay? Like this one. This is the Frisco peak. And in order to have the maximum sensitivity, you can put multiple telescopes. For example, on this peak, okay? You can really place a circle of telescope, each of 60 degrees. I'm sorry that the 3D is not perfect. But basically you can cover the full horizon, okay? With a few of these instruments. And this allows to multiply what is the magic telescope, field of view, which is few square degrees, to really hundreds of square degrees. So you can be sensitive to shower from town, between us, basically from all the directions, okay? I hope you got the idea. How is the performance of this kind of instrument? So about the collaboration, as I was seeing you, it's US and I want to say that the principal investigator is Nepomuk Ote. I hope you know here. He's working in Georgia Tech, and he's really the main driver is the person that did most of the job so far. We have Georgia Tech, we have the University of Utah, we have United Kingdom, the University of Durham, and few institutes in Italy, okay? University of Padua, myself and Jose Mariotti, plus University of Bali and INFN. And I really, you know, when you're working in small collaboration like this is really fun and you can have very flexible discussion without too much politics. And I really, if you're interested in whatever part of this, we need manpower, especially if we get funds. I really invite you to join our team to get in contact with us if you're interested, because it's a fun collaboration, okay? Here is the link for the email. So coming back to how many, how much, how big do we need, okay? And this is done with Monte Carlo, you need to play a little bit, and this is reported here in this important work in this physical review, okay? So first of all, if you check the sensitivity in function of the energy, okay? This is energy, this is flux. You see that you don't need, as I say, is important the field of view, but you don't need a very big telescope. You are more or less at the saturation, okay? So it doesn't really change if you do a telescope that is 10 meters or 100 meters because the size of the telescope measures the density of light, okay? So the signal is so strong that with 10 or 100 meters, it doesn't really change, okay? So you don't want to make such a big telescope. This is different for magic. For magic, we need to see very faint signal, okay? And that's why we need a very big telescope. Here we need to see strong signal, but very rare. Also, you don't need to go too much high in the altitude because of this geometry of the system. So, well, zero, you don't see very well the shower, but if you go to 1 kilometer, 1, 1.5, it's already a good altitude, which is also good to build a telescope, okay? What you need is, what is more important is to have this large field of view, okay, that absorb a very wide area. And what is good is, okay, this is the region where you expect to have your events. You have a neutrino that is exiting the earth. In this band here, it's good to have a veto region from the sky to have like a calibration event. You expect to have some shower now, gamma shower from here, rarely. And again, the size of, so the width of the thickness of the field of view was optimized in the fraction of the field of view above the horizon and below the horizon. And again, you see, you don't need that big field of view because your shower at the end is contained in one small portion of your field of view. Okay, so pretty simple. It's just a reuse of one known technique with another purpose. It's not that small because you have a telescope with, I told you, a spherical profile overall, spherical profile. You have a focal length of 4.2 meters, okay, from here, so the distance from the mirrors to the camera. You don't need very, very precise optics because the shower is an extended object, so you don't need to have very precise mirrors like the optical telescopes. What you have to have is this very big field of view, 60 degree times five, okay, remember magic is two times two or three times three. Okay, this is 60 times five, which by making the number comes to a telescope that is 12 meters in this direction and three meters high. Also it's much simpler than magic because you don't need to rotate the telescope. Okay, the only thing that you may want is to elevate, but in principle, if you don't want, you can even put a telescope that is in a stable position in the optimal position and you don't even need to move it. This is really important for such big structure because moving this big structure is pretty complicated. Okay, here in Padua we made this preliminary design. The camera, okay, the camera is this part in which you have, you must have several pixels, okay, and the pixels are silicon PM, I will get back to that. The novelty of this is that in order to have such a wide field of view, which is not usual for a telescope, in order to preserve the aberration, you need to have a curved shaped camera, okay. In order to observe the right part of the mirror. So, for example, this part of the camera will see just this part of the mirror and this part only this part of the primary mirrors, okay. It will be, there will be no shifter there, just everything will be, must be remote because we want to have many telescopes and we don't want to spend that much time for an instrument that is really waiting for the event. Okay, so there will be not much to do, but for wait for the neutrino to come. So we plan remote operation. Then we started just now the optimization of the optics, which is also a funny activity here in Padua with this program of ray tracing, in which you can really have the best image in the field of view with such a strange geometry. It's important to mention that this idea, okay, this idea of trinity came by the experience we had with the chairing of telescope and by this very interesting study from Juan Cortina in Barcelona now in Madrid. Ruben Lopez Cotto that was a student PhD student in Barcelona and now in Padua and Abelardo Morellejo, maybe you know some of these guys, which basically had the same. They did it first. This was 2016 of this rectangular telescope. Okay, but now see the size. This is 15 meters and this is 45 meters and this is 17 meters. So this is basically like a very huge magic telescope or very huge trinity. Now again with the with a very large field of view. But this was planned to do gamma ray astronomy. Okay, so you really look at a big fraction of the sky with gamma rays something that cannot be done for the moment, not with CTA, not with magic, not with any other instrument. You can get 100 or two or one TV. Okay, so this is a curve of the sensitivity, for example, this is one TV, the sensitivity of this project called Macete Macete in 50 hours was pretty similar to what is magic magic the blue line, and almost an order of magnitude better than has, okay. So really good sensitivity with this instrument if it was built, it would have really a good observation, a very good observation of the sky. Okay, it's a very nice paper I recommend you. Okay now to build this instrument you need to have mirrors the mirrors I was telling you you don't need to have that much precision. These are pretty good mirrors this is one prototype that was made for CTA that we did in Padua. Look how peculiar it is you need to have a large mirror so you want to have it lightweight so you have one layer here another layer on the back and the separators that keep the shape. And you need this PSF of a little less than 0.3 degrees which is very easy to reach. One telescope you have either 36 one meter square meters or 144 quarter meter square meters. Okay, I don't think I need to go in this forum in details about the techniques. But this is something that can be made in repetition replica techniques. The camera is pretty innovative because what you have to do to have this curve camera is to use Silicon PM. Silicon PM are small but very performing photon detectors, in which you that you can put on a camera they are substituting in more and more instrument that standard photo multipliers. On top of the Silicon PM you put a light guide that focus the light there and this allows you to really shape this your focal plane and or your sensitive focal plane as much as you want. CTA is extensively using Silicon PM to make their cameras because they're pretty sensitive instrument. So now I was saying you need one big if you put them in a circle you really multiply by six or by six the the the effective volume of atmosphere the effective area. We computed that in order for the for the instrument to be successful by by projecting the sensitivity I will get back to that. We would like to have we think we can manage three arrays. Okay, three location in the world with six telescopes each. Okay, and maybe South America is again a candidate. Okay, so we start here with one telescope. If we get funds, we will build all six in Utah. But we know that we have pretty good observatories in the Hawaii in the Canary Island is possible in China Tibet, possibly in Australia, or maybe South Africa. I'm not sure, because of the hype. In South America, you have higher mountains, but I'm pretty sure there are some location here maybe in which we can really find a nice, a nice place. Okay, we are not now is too early to really start negotiating with the sites and looking for sites we want to have first our first successful instrument there. Okay, so that that was where Frisco peak is located and we are in negotiation with the local authorities to build it. So what are the expectations for these for the sensitivity of this instrumental. So, first of all, because of the, because of the, the wide field of view, every year we will basically see the full half of the sky. Now, remember, we, we can detect either diffuse neutrinos. Okay, of that energy, or neutrinos coming from specific sources in the sky. Okay, so let's call them point light. So we have a pretty wide sky in which we can look for our data. We expect, if you have this area you can count more or less how many TV, TV camera burst could appear per year, and it's about 10, 10 per year that can certainly be T happens in the field of view. Every night instead you have you can scan just just have to say a street of the sky. Which is anyhow pretty much extremely much then then what what a chair and cove telescope can do. Okay. I was saying that, in principle, you can keep the telescope pointed toward the ground, but this is a perfect chair and cove telescope so if you want to observe. Gamma reverse, for example, not the neutrinos but the gamma rays, you can really point the telescope up and track the source so that you have sensitivity for. Yeah, for for a peculiar event that is happening in the sky. But this is not the main goal of this. This is not the sensitivity. Okay, so let's start with the diffuse neutrinos. And you see here that we have the energy range. Okay, 10 to the eight 10 to the nine GB of the primary neutrinos. You have here all favor sensitivity. These are the, the ice cube detection points up to 10 to the six GB. And here you have the sensitivity from this radio telescopes radio neutrino telescope or OJ. And this is the extrapolation of the sensitivity. Okay, of two sensitivity. Okay, here. Now, Trinity Trinity if it's completed with 18 telescope you see that it's pretty deep here and it's in a pretty deep in a region. of energy larger than ice. Why so deep. Why so deep because ice cube as one or two square kilometer of ice. Okay, but Trinity has hundreds of kilometer cubes in the atmosphere. Okay, that's the the interpretation. Now, we don't know what is the flux of neutrinos above that energy so we have to extrapolate. And we did this exercise and this is the energy of the neutrinos. So this is the extrapolation in which there is no cut off. And here in in 10 years I think 10 years. Yeah, we will see 68 neutrinos. Okay. We will be able to make a pretty nice spectrum. Okay, if there is no cut if there is the hardest cut off that you can imagine this one, we will get just six. Okay, with these telescope 18 telescope that we have. Okay, so, in principle, we have anyhow a sensitivity for this for any situation. However, what we can have is, okay, this will be. Sorry, this will be important anyhow. Okay, so by detecting these, we will be able to feel this part here in 10 years with a pretty, pretty cheap instrument. Okay, 15 mega dollar. If you ask what is the scale of cost of the typical and trim experiment is pretty much more. Okay, then we have these prospects, which are more maybe how to say exciting for neutrinos emitters sources that can detect that can emit neutrinos. Like for example, you can, you know about this and GC 1068, which is a galaxies that is is the best candidate at the moment for emission of neutrinos because you have gamma rays produced by Hadron's and you can expect to have neutrinos there. Okay, so these kinds of sources they can appear in our wild field of view by serendipity or we can move the telescope and point that source. Okay, increasing the chances. Okay, so I'm finishing now the takeaway message is that thanks to just a wide field of view. Okay, and the specular design. You can boost the technique and the challenge of technique to be sensitive to the skin down the tree. Okay, so at the end, one small telescope like these corresponds to really many, many, many big telescopes. The sensitivity is pretty interesting here, and it bridges to regions the region of ice cube at lower energies, and the region of the radio the huge radio installation like ground, for example, you see here grant, which has sensitivities at at higher energies. And that's all we have completed the conceptual design and we are applied for funding and we hope we get funded for for the first prototype to be installed in the US. And I have reached the end. Thank you very much for listening. Thank you very much. It was a very interesting apparatus, the Trinity and all the talk in general. So, as I said before, thank you, Miguel. So for the people that is following us in the YouTube streaming, please you can write the questions there and we can address them to Miguel it for the people that is here if somebody want to start with a question. I think we open the western session. I don't know if there is somebody I'm going to check the Nikola Bernal has a question. Yes. Thank you for the nice talk. Right back, you talk about the funeral. You saw a plot about sensitivity was for all flavors. So I was wondering why all players because they understood that you were only sensitive to town neutrinos right. Yeah, yeah. Sorry, I didn't make that clear. So the situation with with neutrinos cosmic neutrinos is the following. You have, when you have a source in the sky. Okay, you generally produce by standard standard mechanism like pie on the case or these kind of things you have to produce neutrinos of the three families. Okay, with the following. Sorry, new with the following ratio one typically one to zero. So at the source at the source you have twice new neutrinos then electron and zero town neutrinos, but then the neutrinos cross big part of the of the Cosmo. The most of the theories predict that by oscillation at the earth, the, the, the ratio between between neutrinos is pretty, pretty, pretty perfectly mixed. Okay. So now we are sensitive only to this part here. Okay to this neutrino here that the town neutrino. Yeah, town neutrinos, but at the end, this town neutrino was generated by all neutrinos. Okay. So even if we are sensitive to just one species, these species originally come from all flavor neutrinos. So here, by all flavors you mean that you some this and this contribution. Okay, thanks. So, we have some questions from YouTube, or maybe if there is somebody here in the, in the, in the zoom session, hold, hold, for a moment, the question, the question, now we are going to address the one from from YouTube. There is the first question from Claudio Alejandro Moenato little that he's asking why the field of view of the detecting neutrinos a few degrees from the elevation angles. This is, he has two questions. This is the first one. And the second one he's asking how you can differently differentiate a chair and come from this ultra high energy cosmic ray gamma rays or time neutrino, if there is a kind of means. Okay, so the, the sec question is, is this one. Yeah, it was shown here. Okay, so you have a shower. It doesn't really matter. This is a particle shower and this is gamma or tau or can be a proton. Okay. Now, if you have, this is the particle so mostly electron and positrons, and then out of the particle shower, you have your chatting co flight here. Okay. Now, normally, normally, what we do with gamma rays is that if you have your, your telescope here. Okay. By the shape. Really, these different particle they have different shapes. Okay, so you can discriminate the event gamma from proton by the shape in this. This is not what is normally done by by magic. Now, is in this case, as you see the, what you have left you have. Sorry. You have a drone component. Okay, here. Sorry. Too much technology. How can I clean this I cannot. Anyhow, the, the on the on the left plot you see the, the proton event so that the normal can be a gamma can be a proton is very far away from the telescope. Okay. So the red part is the shower that the yellow and that part is the particle shower. The lies, the lights, the technical flight to get absorbed what you just have new ones more new ones can cross very large fraction of the atmosphere. The tau lepton emerging from the town of three not happens very close. Okay, so that's the way you separate the image you see on the right you have a town in your shower image and on the left you have a background event. They are pretty easy to discriminate. The read this the first question was to where was it. Why you need this part I was saying that you have. You have your events. They happen here. Okay, sorry here. So this is the horizon. They happen here. But, you know, the event is not kind of a dot is a is a wide image. And if it's not that precise, you don't know what you can, you can really easily discriminate event, but you cannot very precisely determine the direction. Okay. So if you have one region here in which you can expect now events directly not neutrinos because this is atmosphere. You have a region in which you can kind of calibrate your instrument you know that you have event from here, not that many and you know the direction you can understand where they come from. Okay, I don't know if I answered. I mean, we can we can wait here in the, I mean, he can answer in the in the YouTube chat if he understood the, your answer, but I guess that is the, it was very pretty clear. So, we have another question from the from the YouTube from Victor Muñoz. He's asking. It is possible that the high energy, high energy esterine neutrino could also produce the same kind of signal of tau leptom. Have you studied sensitivity for such type of BSM scenario. I am not that I'm not an expert of sterile neutrinos but I think the words sterile is is suggesting the answer. So here. So sterile neutrinos can can, from what I know know they are candidate matter because if they are in big quantities, they can interact one another, but you need to have many of them. Here, we need to have one one neutrinos, okay, doing these kind of things having a certain probability of conversion, you need you need the charge particle here. If the neutrino crosses you don't see it, you need the neutrino to become something charged, you need the charge particle to exit the ground at the right direction with the right energy for you to detect it. Okay, so that's why I think it works only with with the town neutrinos in this technique. But maybe maybe there are some more. Now I'm kind of the imaginative. There are some studies in which you can use the solar colonas as a place in which cosmic ray particles can interact. I don't know if the town if sterile neutrinos but it doesn't have a strong velocity know so you don't have direction so I'm not sure so I'm not for as a nurse giving technique, and I don't know about others. Okay, so I don't know if I mean, people in YouTube can ask more questions, they can write them in the chat. Meanwhile, we can we can continue with question from here from the audience. I don't know if the, the rest of the people, maybe Walter has a question. So, yeah, so yeah, I had a very simple question so they just looking at actually this light that you have right now. And then I think that I saw one of your plots where use with the sensitivity doesn't change much if you go higher than one kilometer or something like that right so there's like a big jump in the sensitivity. Yeah. So, but looking at the picture that you have there. So, so you did the telescope is really like on the edge of this of the of the color the light right yeah why why is that the sensitivity doesn't change much once you go one kilometer higher to look is this geometry right here so this is, let me try. If I can explain okay so this is the exit. This is the exit angle from the ground the elevation of the shower. Okay. And then you have your chairing of corn here. Okay. Now, you are very very far away. And this is the altitude sorry forget this is the 1000 meter of the telescope. If you're here or here, 2000 meter. It doesn't really matter you are hit by you are in the in the shadow say chairing of shadow, okay, or the event. And the original towers cross the right path in the ground. Okay, so what can happen is that you have to go at 5000 meter that would be bad. Okay, but consider the geometry so let me do it here. If you are at 1000 kilometer. Here is enough the distance from the event. It's good not to have to dim light. Okay. Clearly if you are at 5000 meter. Okay, you could see the same geometry but now very, very far away and this would be too far from the extraction point. Okay. Okay, so are there other questions I have one question when when you were talking about the possible location for the for the telescope. Do you doesn't it matters for instance the possibility to access that one part of the field of view also could see towards the sea to the ocean or has to be inland. The density of the ocean is not the different from the density of the rock in the first I mean the crust. I don't know exactly how deep so oops. This is the path in the ground I don't know exactly how deep it is but I know that in this part here the if it's water of rock doesn't really matter so it's perfect if your telescope as magic looks at the ocean or at a mountain doesn't really really matter. So consider that you can adjust a little bit the orientation. If you know the orography very well. It's just a matter of having the right position for for your telescope. But in that sense the kind of the ambient humidity of the of the sector that you see sure. Exactly. Is it important for the chair and go for exactly with the right place or exactly. Exactly. Sure. Exactly. So what you need to have is that from the extraction point to your telescope you need to have as dry atmosphere as possible. As dry as possible really you don't need what you cannot do it in the town. Okay. But consider that the event is not is not that far away and the signal is strong. We have strong signals so even if you have clouds for example high in the atmosphere you don't care about them. Okay. You need to have not too much probably aerosol in the ground layer. But as soon as you have you know typical situation of. I don't know. There are several places in the world that can can do that. But you're totally right. It doesn't need to be too polluted. Okay. So in that sense it kind of has to be a kind of isolated place. Yeah. For example, you have pointing towards without any any obstruction. You need to have so to say clean atmosphere from few hundred meters maybe to 1000 meter is where you don't need to have aerosol there but if it's even if it's on the ground layer like in the desert, you don't care because the event happens on top of that layer. Okay. No, because I was wondering when when you put the case a possible site in Hawaii, I thought maybe Hawaii is too humid, but yeah, you know, you have the volcanoes and you can go higher and escape like maybe from the. I wonder if there are so many telescopes there. I'm not sure that is humid, because in the in the tropical parks. Sorry. In the tropical part you have this dumpster circulation that you have a clean atmosphere. If you go to few hundred meters high so I don't know but from the fact that you have so many telescope I think it's a pretty nice place. I'd like actually I'd like to visit to check it myself. No, because when I when you show the the map of the possible locations, one of the telescope was was in the ocean, but also looks to me like it was kind of Easter Island, because that reason I thought maybe. I put I put the markets I put the market very, very rough. Yeah, I think a telescope in Easter Island would be also awesome. Now anyway, so what one another question let's say a how is that the potentiality to combine this type of observation with, I don't know surface detector or some kind of complementarity for kind of to have many, many type of observatories in the same zone. So for town neutrinos, there is no need to combine it you don't gain anything. But you're right that if you put these instrument close to Hawk or close to even to grant grant is a radio series of radio antennas, if you have these wouldn't are because you have more accessibility and you can put it there but combining information. So the other thing that I can think of is for flaring events so if you have a flare, and you have a check of telescope and this instrument, looking at the same event at the same time. It could be interesting, but it's hard because the check of telescope point in the sky these points in the ground so you have to wait for the source to be at the right location so it will never be synchronous. So as a short summary, it doesn't really help a lot but scientifically wise but practically, of course, having several instrument is one side is good. Okay, yeah, because I was thinking when when they have this early detection, I don't know for black hole mergers so that they expect some neutrinos coming out from there to very high energy. No, it doesn't matter to be on the same side you just need to point at the same time. But to be on the same site it doesn't change. No, this is having multiple of these throughout the world this is interesting, a different position but not at the same site. Yeah, that would be the scenario in which you can have in the same line of sight from the town neutrino let's say, another observatory but in the other side of the earth. Exactly. But say that point to the same part at the same time, yeah. Exactly. Okay, good, good. So and I don't know if you can mention something about the indirect search of the dark matter is it feasible because you show it one that the capability of 30 with 10 years is much, much lower. I mean the sensitivity much better than the other competitor like ice cube. Yeah, I mean, of course it has to be producing town neutrinos but for that matter, no, the only the only thing. No, for that matter you are not competitive to sharing of telescopes normal. But for this, I don't know if you heard about this cradle collaboration this super shower this interaction in that in the sun surroundings. Then yes, this instrument can be useful because it has very strong. Very strong very wide field of view so maybe not for that matter directly or maybe some fancy model, but for ultra high energy events, strange events of fundamental physics in that part, maybe, maybe yes but for TV dark matter. Other instruments are more sensitive. Yeah. Okay, so I don't know if there are other questions there are some comment, one comment that I don't Vincent he's saying thanks for the nice talk. Thank you for the invitation and for listening and I don't know if there are other questions from here from the people in the audience. Otherwise we can, I guess it's time to, we have to say, we have to let me get it to continue with the his activities in the university. So, thank you very much, Michele, Michele, thank you. Thank you for coming here to accept the invitation to give a talk in the physics. Thank you. And for all the people, you know that we are going to continue with the webinars and you can follow us here in the in YouTube, maybe to subscribe to the channel to be updated with the latest news. Thanks for coming in research in particle physics, particle physics, astronomy, etc. So, see you all people and stay safe. Thank you, Michele. Thank you.