GEOTALK | Robert Lindsay, Jacques Marteau & Lumkile Msebi | Muo

I think I can pause it once it get going hello hello hello hello we hear you check hear me that's wonderful and we see the slides hello de long time no see I for is in fact I ask yes how you how are you doing I'm good I'm good good to see you I mean good to see yes nice nice yes I'm probably going to ask you at some point how can someone interested join this but but I I leave it oh yes but you just tell me I will add you to the EM mailing list and you will receive all the information uh Bruce is in the list as well as some people from Ms um but uh just after the meeting send me your email and then I will put you in the users uh poll list so we'll get all this information about the project and things like that thank you very much yes very good thank you I'm I think think uh should I start at some stage as you wish Robbie we're waiting for you who's the who's the chair someone should be chair yeah yeah yeah okay I'm going to introduce myself and stu okay let's go maybe you Robbie you tell us who are people in the in the room because we we see people in on on video but we don't see people on the in the room okay L gentlemen I've been told I should start I'm just trying to figure out where I am I think I've got to the sound goes in there and the camera goes in there so hopefully people on uh on Zoom won't be talking at the looking at the back of my head okay just to explain I'm Robbie Lindsay I'm from the University of the Western Cape I'm uh from the physics department there though I have two or three other jobs as well but that's the main reason why I'm here today and this is a rather weird thing you know I certainly didn't expect to come and talk at the geophysics department at vits it's sort of good to be at vits I also at least one physicist that I know um the reason that I got to be here two physicist the reason that I we ended up here is a few of us have had this what we used to think was a mad idea but now it's sort of become mainstream the idea is that we want to build an underground Physics laboratory in South Africa and as especially the physicists know uh these Laboratories are very uh popular these days because of Dark Matter searches and so on so I'm going to explain briefly why we need that had to say a bit of the history of underground physics experiments in South Africa which is actually started a long time ago but there's not much has happened since then um we uh are at the stage now where we want to develop this lab in the Yugo tunnel outside p and we need some geophysicist which is the main reason why I'm here and thanks to lumil who's also going to be talking we made contact with the Vitz geophysics Department we're interested in geophysicists and Mining Engineers people that know about doing things underground so okay just to explain the talk this afternoon I'm going to just give an overview of what's Happening uh then for 15 minutes something like that then Lum will talk a little bit about the muon measurements specifically and some of the uh background of what we need to do to figure out whether this is worthwhile doing you know is it worth uh having a lab in that tunnel or should we go to a deep mine or what should we do and then lastly and probably most importantly we're going to have somebody on Zoom the two of us are here but we're then going to have Jac matau from France on Zoom he's a expert on measuring muons on muography and so he will explain the muon measurements that we're doing in the tunnel why we're doing it what we want to do and especially try and encourage some of the geophysicist to get involved in the work there because he is simply measuring the muons but to really know how effective the overburden is he's interested in things like gravity measurements and and stuff like that but I will leave that to him okay so I'm just going to give you a quick overview of what's uh happening or what we're doing if I can if I can go to the next slide which I can't ah there there we go okay I've already told you there there are going to be three speakers and what we're going to be talking about you'll hear that soon enough okay for those who don't know and I know some people here are experts on that um Vitz actually was involved in an underground physics experiment which with one of the Nobel Prize winners for finding the neutrino this is something uh um frle shell shop which some of you may remember he was one of the big guys here at Vitz for a long time uh he when he was still very young got involved in this experiment where people were trying to measure the neutrino neutrinos are really very popular thing in especially now again but in those days in the 60s they were only only just been discovered and it was really difficult to measure them in any sort of way the background kills one you get very very few counts it has a very very small interaction with anything else and you had to go to places then where you didn't have background and the erpm mine in here in withv rant was a good place to go and Sal shop convinced um Frederick R Who eventually won the Nobel Prize for discovering the neutron and the nutrino to do experiments here and here's just a copy of their paper and something where it was discover uh published in ferlet and here's a plaque which is at the erpm mine I stole this slide from ilas who's in the audience here there's a PL at the erpm mine saying this is where they found the first natural high energy neutrino was observed okay so the jump ahead 30 40 years or whatever Sean Luke can you mute your phone I'm told I don't know who Luke is but he seems to solve it okay move on 30 or 40 years can you close your mic L ASW okay so then Sean vard who at stos head of Department of the physics at stos he had this idea that maybe we we we have an echo yeah okay now he has closed his mic he fine okay it's that was just for who's commenting okay we've solved the echo problem for those who are worried Sean wart he was looking at the at the um tunnel outside Paul between Paul and Wester I know you've all driven through that tunnel probably or most people have but you never look and if you you look you will see that there's actually a whole separate tunnel the what they call the north bore and so one could actually do some experiments in there and we went and actually measured a few things like what's the raid on what's the background and we sort of vaguely thinking about a a um an underground lab uh Sean then gave a talk on this somewhere in Europe and it got published in physics credia and that sort of got some people thinking about it again um and then there was a another talk which actually led to people being aware of it and led to the more recent talks about it uh this was the case for an underground nutral facility in South Africa and you may recognize the um speaker there as somebody who's well known at Vitz I think I was worried or well no I was hoping he might pop into the talk but I thought that was extremely unlikely anyhow so Zeon um uh pushed this idea as well and he's still very keen on it so anybody at vits if you want to get into good the good books of the big boss you should be linking up with the this okay this um was so some people thought talked about it but to give you an idea it wasn't really a a very much um serious discussion for example you see there's somebody M ruen I don't know if anybody knows m ruen i very much doubt it because actually the name is wrong his surname is spelled wrongly so that was you it wasn't that that serious an operation but okay underground labs as I mentioned is Big Business these days um and I'll I'll tell you about snow lab which I visited there's at least 14 active underground labs in the world and if you look at the world you see there's only three in the Southern Hemisphere and for the Dark Matter searches there are some reason for measuring in the north and in the southern hemisphere at the same time you see three in the southern hemisphere Supple in Australia is still being built so if we're quick we can actually beat them and this one is not being built yet that's the one I'm talking about and the one in and in uh South America is called Andes it looks um very good there with two flags and a big name and whatever that is behind us they they they've got fantastic plans for the laboratory there it's going to be in the a road tunnel which is being built between Argentina and Chile except it's not being built it hasn't been given the goahead yet and Argentina is bankrupt so it's unlikely to happen soon yeah anyhow so this is what the north B looks like there's some uh the road hasn't been built it's all Rough and Ready and what whatever and of course you know there's not much what one can do there but when we started talking about this um the first person who is on the call actually farus Malik uh she's a French physicist who works at Atlas but she was born in Algeria and grew up in Algeria and she has always had this dream that maybe we want to have an underground lab in Africa now that was just a dream but dreams are good because sometimes dreams become reality anyhow um then recently we we then said we want to do some more experiments in the tunnel there and they said to us no you can't do it because the Yugo tunnel is being upgraded uh that that North ball which I just showed you is going to become the road if you travel North you're going to be traveling in that road and the one the present one will only have traffic in One Direction the number of cars on those roads are uh in the tunnel is now big enough that they need to open the north bore so that's a a real problem uh but on the s all said it estimated this this is a two and a half billion Rand project so a few of us like me was stupid enough to think well maybe that's an opportunity that's a problem if they're going to build the road but it's also an opportunity a lot of money is going to be spent can't we build a lab off that North bore the way it has been done at several labs in the world modan is the famous One in France the grand Sasso in Italy and so on so we formed this we've now got a steering committee that looked at this we had a workshop in January where we invited a number of people like the ex-head of Madan the head of um snow lab in Canada and so on and these people all came and they were quite supportive the underground lab people as far as I can see there's competition but on the other hand there's a lot of collaboration as well because they have the same problems how to do things underground and so on anyhow so this thing has suddenly now got some legs just to give you a bit of the WC background I actually for years ago five years ago got involved with my colleague smarajit Trak he was a he's a research chair at WC's now this research chair has come to an end but he's still a nuclear physicist there he was working on nuclei like Xenon which is used in these underground experiments to look for neutralist double beta Decay Decay and through that he got involved in Nexa which is one of these big um collaborations to look for neutrinos we joined in 2020 and as you can see it's mainly the US and Canada however WC is now on that list as well now he then asked me to join because it turns out that I've been working on raidon in South Africa radon in the mines is a big health issue and so on and radon measurements is really important for this stuff as well so suddenly when I was about at retirement age I got involved in a whole new project looking at nexo and now I'm involved in another one looking at this tunnel idea so nexo of course is one of these huge big uh things it's it's 13 meters by 13 meters if you look at that if you look at the scale of the man on the side there and we have a few people now who's involved in it there's um Smit and a few students and myself uh we then visited the us as well and spoke to went to Stanford where there was a big collaboration meeting and then I went to snow lab as well there we are in the cavity in snow lab which is a nickel mine it's about 2 kilometers deep it's quite uh quite deep and that's probably the best known underground lab in the world that's where neutrino oscillations were discovered and so on okay just to remind you uh especially if you're not working in this field so I've just used the model of the um uh nexo uh setup there the backgrounds which we have to worry about are muons these things coming from the top and most of the discussion today are going to be about those uh muons we've got to get rid of them you also have in the walls that's the other worry you have the natural Decay series uranium 238 thorium and potassium that gives you gamas the good thing about those gamas is they only go up to about 3 Mev so you can actually Shield against them you can have water shielding or whatever that's why in this uh setup here the actual detector for the Nutri noce double beta Decay is this thing over there but there's a whole bunch of stuff around it which gets rid of the um the gamas in the surrounding area the problem with the muons are is their energy is much bigger in snow lab they also put um uh stuff on the wall to try and reduce the raid on escape and so on okay then the biggest problem and that's the one I'm working on which I just mentioned here is that inside this material you have things like copper and copper gives off radon as well so you have things within your uh setup which causes background as well okay but back to the tunnel so there's the tunnel which most of you have driven through and if you look on the left hand side there there is this North Pole it's totally undeveloped as you could see they're going to have to build a road they're going to have to concrete the inside and all sorts of stuff like that it's going to be a four fiveyear project um and what we are now trying to do is to try and build something like what I've got on the left here I uh have a have a sort of um slipway where one can stop there and go in it's probably not going to look like that because sunal doesn't like slipways because then if people are driving 100 km an hour and some trucks are pulling off then it's not ideal here's an example of one of these Labs um this is the one between France and and and Spain Okay so we've started we've done some things we've measured some radon uh well sorry let me just first show you the the mountain outline so this is what the mountain looks like this is the Paul side that's where you're driv in and that's the exit on the uh Wester side on that side and as if you look at this um map of the mountain the middle would be somewhere there but um it looks as if the biggest overburden is there this the mountain is high but it's not quite as good as what one would have liked we would be better off in a deep mine for example but mines have other issues uh so we want to certainly choose the point which is best and that's why we're going to measure the muons the muons as I said has these really high energies and so you can't really Shield them very easily that's why we have underground mines okay um this is just to show you that we have done something this is the radon we measured in there it's about 50 be per cubic meter that's not ridly High I mean in this room the value is probably 30 or something like that uh we measured the wind speed and a few other things I've now also measured for the physicists who are here we did some gamma measurements for those who know if you go and measure in the environment this is the sort of background radiation that you see with the sodium iodide detector and above 3ev you do see some things but those are mainly um due to the muons so those ones over there so what I did take my sodium iodide detector in there there's JJ Fel from stos who was involved in the measurements I first counted at my house so I turned down the amplification so that I now have from 10 to 40 meev if you do that and you measure in the tunnel you get nothing in this region because there are so few muons these gamas are formed by muons getting through all that material all through the mountain and then forming uh and then causing other arrays to take place this is a log scale of course so even at my home the these are very very few counts in a sense uh this is per hour uh but in the tunnel I got nothing of course there are some just just didn't count long enough to get reasonable enough statistics okay um so I uh here I've got some numbers but that's uh I won't go into the detail of that Jack's going to be talking much more about that okay uh so what's the status this is at the moment it's run by a steering committee committee which has got stush Sean Bart um um and uh uh Richard Newman Richard Newman is taken sabatical this year and is working as a working on this project as the project manager so he's running most things he's busy this week otherwise he probably should have come up with us as well uh so we had this idea we spoke to various people and uh eventually I spoke to Rob Adam I thought he might have contacts at sunal and knows how these things work as you know he used to be the DG of the DSi and now he's working at SAR at the astronomy people uh he then with him and Richard Newman and whatever we got to talk to um teal takalani narui at um DSi he's involved in the Astro group and so he's very aware of the whole uh justification for the ska the story was we build this big scientific development in Africa people will come for from other countries to do the experiments and and a lot of the funding will come from there but it'll have huge spinoffs for South Africa and at WC it has been really useful we've got lots of Astro people now with post dos and so on so we talked to him and eventually we spoke to philm Daka who's now retired as the D DG of DSi and we convinced them that this was something worth doing so they gave us 5 million Rand seed funding uh that might sound a lot to to to people who are used to the money we get from the NRF but don't don't hold your don't hold out too much hope because about 4 million of this is going to go directly to the engineering company who's doing the design there's a engineering company smack that is working with sunal to to look at what if all the stuff that needs to be done they then going to come up and say this is what needs to be done it'll go out to Tender later this year and then people will have to Tender for that and we're under pressure now to come up with a a plan for the what the what the cavity is going to look like and we actually then spoke to smack as well so we've got smack we paid them 2 million Rand already or we'll pay them soon um and for that they're going to come up with a workable model for what this cabin is going to look like how the AIS is going to look and so on and our we only have a a rough estimate this is going to cost 200 million Rand maybe 300 million whether we're going to get the money anywhere that's the um the next question we still have a have a sort of um interim ing committee we don't have a formal structure yet if anybody wants to join you're very welcome we're not even sure what governance model we're going to have uh Rob Adam who used to be a DSi in charge of NRF and so on he thinks being a a facility of the NRF is not a good idea which I found quite funny so we won't be like um itemba but we may work with them uh so what do we need we need some geophysicist to tell us about whether this uh cavity is good and maybe as you could see there are different areas which are more granitic and some is standstone what should be care we be careful of what should be looking for and which part is going to be the best so apart from the muons there are other measurements that can be done we certainly need some mining Engineers if anybody knows of a board mining engineer who would like to give us some advice because when we talk to the engineering company they ask questions and we don't have the answers uh what we need as well of course probably that's the main thing is we need funding for the cabin but um thus far DSi seem to think well I'm not I'm sure they're not going to just say yes 200 million Rand but it's luckily not immediate it's going to be paid over several years I assume and it looks as if there's support from other parts in the world but most people say South Africa better build the thing then people will bring their experiments and have collaborative things I don't think anybody abroad is going to say here's money to build a cavern there unless they have a specific interest in a an undergr lab and they don't have funding for it uh here's just a picture oh um can I go back here's a picture of Richard and farus Malik who as they say was somehow the driving force and she's the chairperson of the steering committee uh who came up and has really got this going and she's on the call as well and Richard now is spending a lot of time looking for it if you go Google Paul underground lab you will find various things we after this meeting that we had in January there were several articles on new news 24 nature and whatever and there's an archive paper you search on the archive for Paul and whoever's name you will you will get that has a whole bunch of people who were involved in the discussions thus far okay that's my story lumil is going to tell you something a bit more about the measurements that we're thinking of and which we want to do before um jacqu in France will tell you about the M on I guess we'll have I guess we'll have questions at the in e e thank you very much k for the lovely introduction uh I'm sure by now we do have some geophysicist would like to come on board after this lovely introduction now uh it feels good to be here I was a student here it feels good to see some old faces as well um we used to have a practical here on Fridays so uh it used to be late in the afternoon when I was doing my first year so I I see the tradition of doing things late in the afternoon has continued on because uh but then the disadvantage is that we never had some lovely Refreshments that you guys have for a Friday afternoon uh In Absentia let me also thank the head of Department I don't see her here Professor dran uh she used to be our lecturer In Absentia I would like to thank you very much for sort of uh giving us this communication channel to to speak to Stephanie and then organizing this talk now she she was uh she was she was a very inspiring lecturer to us but then not only that she she was a mother to us as well being first years now I recall just to to say to the audience that's here one of the things that I recall about your head of Department um you know I I recall her calling the two of us my myself and my friend to a office for being naughty but then what happened is that we we lost the key in fact I lost the key to my locker which the locker was situated somewhere in Senate house now called I think now it's called Solomon mang Mouse so the the the the the the lockers were there so I lost the key someone picked it up and then decided to help themselves with the belongings that were in the locker but then we happened to see one of our classmate eating a red apple and the Red Apple happened to be in the locker and and my friend said hey we've never seen this guy eating a red apple before so he's the one so we confronted him and then he went to the head of Department which is professor drenan and then she swiftly scold scold at us for that but then you know she she's been a mother to us because I mean we could always go back to her whenever we had any other issue be personal academic and so on so it feels good to be here now um after this lovely introduction my talk is very simple because I just need to talk about mutes right it's a very simple talk that I'm going to do now as you can see this is what the muon detector looks like uh you have three panels uh so you have three panels there this is the tunnel that Professor Lind has spoken about and then we this is the inside of the tunnel that we plan on building this lovely facility this Underground laboratory so these are all the colleagues we went to go visit this tunnel and then uh um the lovely lady that you see um May her soul rest in peace she left us earlier on this year Lely now I'm just going to give a brief history on meons right now in 190 9 part of the history is that in 1909 Theodor WF he installed a telescope in the Eiffel Tower in Paris now of course that was the highest structure at that time it's about 330 M right the idea is he wanted to understand whether the radiation that he me measured on ground does this radiation come from from the ground or if he were to make at a higher structure would he still see radiation right so he took his electroscope to the highest point which is the Eiffel Tower and then as he expected um the radiation levels decreased but then not to the level that he expected all right so when they decreased you could significantly see radiation right at the top of the tower so there must be some external sort of source that's giving this radiation right at the top of the Tower so this intrigued people and indeed uh one of the persons that further and continued to do uh this measurements was Domino pasini all right so he compared the discharge of his electroscope so he did measurements on the ground and then later on did measurements uh on the sea now the idea is if there's some continental crust radioactivity that happens that affects the the radiation so he should see the difference if he does measurements on the sea uh he also did some measurements underground all right so then he also saw that this atmospheric ions that he measured under when he he did underwater right so sorry he did measurements underwater so he saw that there's a there's a significant reduction of these atmospheric ions when you you measure underwater um and then of course this is a modern day uh Domino pasini with his electroscope trying to measure the discharge of the electroscope there now uh in 1912 Victor H right he he used balloons so he he took this electroscope this world electroscope and then he put them in hot air balloons and then he did to a height of about 5.2 km to measure this atmospheric ions to see the difference up there he did it did uh some measurements at night as well all right so that sort of eliminates if there's a this uh if if you want to know if there's an effect on nons solar radi radioactivity right during the night you would still measure radiation indeed with those five air balloons that he did measurements at night he could see radiation by the way Victor has went went on to measure well he went on to win the Nobel Prize in 1936 um that's because later on around about 1936 two physicist in ctech laboratory they uh they did some measurements all right and then they find the path of cature uh in their Cloud chamber all right it followed a certain trajectory which is strange and sort of gave a behavior that's similar that's that's in between an electron and a proton and they couldn't understand what it is okay later on of course it was they found out that it's meons and we know meons of course is the subatomic particle that we know that of it's got properties similar to similar to that of an electron but that it's just 200 times heavier than an electron now how are muons formed right so you have cosmic rays heating the atmosphere all right atmosphere atmospheric right are being hit by this cosmic ray in the process you have Pion that are being formed the Pion when they Decay they deay into meons these meons have uh extremely high energy and they're highly penetrated so now we did some measurements uh in stellin Bush and at uwc so what you see there is this is this uh uh neon telescope that measures the the meons it's placed right in at uwc at the moment the idea is later on uh at the towards the end of the month we're going to take this muon telescope toward to the tunnel at the moment we just doing some measurements in Open Sky that's just forms part of the calibration and so on so it's got three panels as well all right so your middle panel acts as a veto against your random coincidences now coming to muons and uh some Physics what what sort of physics to to to muon tell tell us um if we think of muons the average lifetime of a muon is 2.2 microc now classic if you were to to sort of measure if muans traveled at the speed of light and uh you wanted to know the distance that they will travel it would be around about 660 660 mters now the atmosphere typically the distance from the atmosphere to the Earth ranges from 10 20 30 kilometers you wouldn't expect a muon with an average lifetime of 2.2 microc to reach the atmosphere I mean to reach the the Earth right but then um what happens that if it travels at relativistic speeds right which is closer to the speed of light something happens which is time dilation right now this is the equation for time dilation it simply means if something travels closer to the speed of light the time passes slowly uh I'm sure many of you uh will have had of the twin paradox one twin remains here on Earth and another one travels to space close to the speed of light when he comes back the older the other tun has become older and this one is still young right it's because of time dilation right time passes slowly right now if Neons were to travel at the speed of 99.99% the speed of light then they would travel a distance of 66 kilom as opposed to the 660 M so that's how muons reach the Earth and that's how they can even penetrate underground as well because they travel at this very high energies now if we were to look at things from a different perspective from a mu's uh perspective what does a muon see right um from the mu's P perspective what it sees is what we call length contraction right in that instance the earth and the atmosphere are traveling at relativ relativistic speeds right which is if Neons travel at in this case okay if we consider if uh the earth and the the atmosphere travel at 99.9 95% of the speed of light then the length will sort of contract okay so that would mean from the mu's perspective 50 kilm is 500 M that's from a mu's perspective right length contraction so that's how muons tell us something about physics uh this theory of relativity now uh I see my colleagues in physics are smiling so that should be right uh now what do meons tell us maybe can they tell us anything about geology uh we know that x-rays x-rays take advantage of the variation intensity in in in bodies right or matter whatever it does right it takes advantage of the variation intensity your makeup as a human being you've got soft tissue and then you've got this bones that are more dense right so there's a variation of density in your makeup in your in your makeup as a as a human that's how we can tell fractures that are in your bones and so on we use x-rays right they penetrate they travel at this speed and then they penetrate your body and then we can use this variation intensity to sort of locate where the fracture is now we can use muons as well right muons uh we can use Imaging meon Imaging or mography and we look at structures whether natural structures or manmade structures to look at to that will tell us what happens with the uh uh density variation in a structure if you were to look at a natural structure like a mountain and so on in this case uh this result that I'm going to show now is they could find that there's a new void in the pyramid using muons right mography could tell that okay uh here you can see there's a m there's a void in a pyramid right it's a natural structure and indeed mography is being used to look at things like blast fesses the papers published to look at things like blast fesses and there's papers that's been published to look at uh to look at uh nuclear reactors the inside of the nuclear reactor that you cannot go into you just look place a m detector out outside and then you you can see what happens inside now of course what I've shown was just 2D right we know that technology has advanced now we can get 3D scans of human but then the way that works is that you just take X-rays at different positions and then you combine that eventually you come with a 3D CT scan right the same thing with the muons you could take a detector your muon detector you place it at different different locations eventually you come up with a 3D scan now there's certain parameters that affect muons of course one of them is uh uh altitude this results that you see there shows you how uh the ion pairs in the atmosphere with increasing altitude how they increase now other things of course would be temperature and pressure variations uh the result that I'm showing is a paper that been published in otoa in Canada uh other things of course would be your geom magnetic latitude and so on so there's certain parameters that affect muons now of course also there's several processes that affect the slowing down of muons as they interact with matter right they slow down those things include the kinetic energy of the muons right it affects and the density of the the medium the chemical composition of the medium all right now uh if we want to look at all of these natural structures and so on we can come up with we can try and understand what happens or how muons propagate through matter in a standard Rock so we can Define what a standard rock is all right it's a crystall in quart with the density that much about 2.65 G per cubic cm meter and then the the the a there which is the atomic number uh no no no a is the is the mass the a is the mass which is about 22 G per mole and Z which is the atomic number is 11 that's standard Rock now we can try and see how they propagate through standard Rock here now physicists uh if they want to know how charged particles Traverse through a medium right they use what we call the stopping power and of course there's uh there's the beta formulas and so on that will tell you how charged particles Traverse through a a a medium right now if you look at the stopping power you can tell how Vons travel through Rock now there's different of course interaction processes that Neons use and those depend on their energies the dominant processes all right uh between 500 GV G and lower that's ionization all right if you look at higher energies like 693 gev then uh the processes that you think of or that will affect uh the the MU traveling through a tense uh structure would be the Prem Stelling P production and photonuclear now here is again if you look at the total mean stopping power plotted as a function of the kinetic energy for three different Rock densities all right if you look at three different Rock densities then you can tell that total uh mean stopping power is a function of energy all right and again you you can look at the muon flux muon flux as a function of the opacity right now um of course we with the with the uh uh muon telescope that we have and fair Fairly recently we've now started to look at the data uh I'm just showing you now just uh one run all right the time distributions um you know um uh different time distributions there and then if you set your coincidence maybe at 200 microc and so on if you want to get rid of coincidences and so on there's a Time distributions if you wanted to look at the time difference between a current event and a pre previous event then you plot your time distributions and so on now uh one of the panels if you look at the detector will have 64 channels one panel has 64 channels right now this is uh uh the results from Just One of the panels and of course statistics are not good because it's just one run yeah so the the the the the analysis of this uh data which is we are still col collecting the data anyway is ongoing and then uh uh now I will just hand over to our colleague in France ja who's going to now talk more about geosciences and meons I thank you okay can you see my screen yes we can okay wonderful so should I start yes please start okay very nice so thanks for uh having organized this nice seminar and thanks for the two introduction by Robbie and Lum I think that I will uh gain some time because you have now all the basics and all the features of mography so as it was explained by lumil the idea is to exploit this radiation that come from the sky and uh the largest part of this radiation the atmospheric radiation is made out of muons those strange particles and so the ID I hope that the CH the the slide that changed okay the ID uh is summarized in this uh slide so you see here uh a mountain this is the Dome of a volcano in Iceland and uh I have drawn here symbolically a shower atmospheric shower of element particles crossing the Dome of this mountain and uh you see the detector the three plane detector that is placed just after the the mountain and receiving the flux of the particle crossing the mountain and of course some of the particles are absorbed by the matter of the the mountain and so what you meure directly is an attenuation curve uh that you will converts after the resolution of an inverse problem into a density map of the inner matter inside the the mountain itself so roughly speaking this is the equivalent of Medical Imaging you see it in a small picture underneath this is exactly the equivalent by replacing the xrays by mu Rays uh replacing detectors uh surrounding the body by our muon detectors and of course uh looking at Large Scale volumes so as lumil said the probes that we're using are Elementary particles so so you have here on the bottom uh sketch all the 12 Elementary particles known uh nowadays so six so-called quarks and six leptons among the leptons you know the electron and the muon now which is a cin of the electron as far as its properties are concerned but for its mass and but for its lifetime which is limited and the mass is the big issue because the 200 uh times more massive uh more important Mass uh of the muon uh gives it an interaction cross-section which is by far lower than the one of the electrons the origin of the muon and the origin of the cosmic race is still not completely clear we we think that it comes from the explosion of a Star supernova and so on and so force and that's these cosmic rays travel all along the universe and are bended and accelerated through the electromagnetic field that they they they find in the galaxies and in between the galaxies but origin is not completely completely clear what is really clear is the chain of production of the muons as uh it was described just before and the cosmic rays which are mainly high energy protons it the top layers of the atmosphere and generating the shower of Elementary particles through the decays of Pion you will find the muon and the muon will propagate from the top layers of the atmosphere down to the ground at the ground level you have to keep in mind that the rate is of the order of one particle per square cm per minute this is to give you the scale of uh the the signal the maximal value of signal that we can get at the surface level there are some small variation which are induced by barometric parameters by uh characteristic of the the atmosphere altitude latitude geomagnetic effect and so on and so forth but more or less this is stable within plus or minus 15% this is uh completely constant uh stable uh in each point of this planet okay so this is really a reference radiation flux that we have and that we get and that is completely for free and that we will exploit in the mography meur the there are many ways of detecting those muons in particle physics you see meons have been discovered almost one century ago these are charged particle negative or positive so this is quite easy and the basic idea is that you want to take a small part of the energy of the muons and you convert this energy inside your detector into a signal that you can measure so the detector that we are using are based on cator and you have the sketch of the detection of the Mion which is uh described above basically the muon leaves its energy the energy is converted uh into a flash of cination light the light is trapped into an optical fiber and is driven inside this optical fiber to a photo multiplier photos sensor or whatever this is one way of detecting the muons and if you make an array of X and Y cator strips then you define a pixel and you are able to identify in which pixel the muon uh passed you can detect muons also with the nuclear emulsions which are the former uh let's say photographic emulsions used in the former devices to make photos in foral cameras you can also detect muons in the so-called rpcs or micromegas which are gazio detectors and here the energy of the muon is converted into an avalanche of electron and so you detected signal in charge okay but basically you see that all those detectors are of the same type you have parallel planes of roughly speaking one square meter because this is something that you want to manipulate by hand so you have parallel planes and all the planes are pixelized and when the muron crosses the planes it left a signal inside the the different planes and you can reconstruct the trajectory of the inent muon this is why those detectors are called trackers because you may reconstruct the track of the incident muon and so since you have the direction of the incident muons you can count in all the direction uh available um to the detector so what we call the acceptance of the detector You Can Count exactly how many track you get per time unit and you can compare this measured number with the expected number in the absence of the Target and of course the comparison of both give you the attenuation induced by the Target so as Lum was presenting there are many many um different measurements of mography nowadays when I started this activity 15 years ago we were almost a couple of teams all around the world now you type mography on the web and you will see that there are plenty of teams who claim that they are doing mography to anticipate the question that you will have what is the resolution of the measurement and uh what is the time needed to make a measurements the correct answer is it depends it depends on the volume that you want to image and it depends on uh the uh size of the density anomaly you want to spot here here if you want to take the image of a Great Pyramid like the one which is depicted in the top uh picture you will need of the order of one months of uh data taking and the resolution will be of the order of the cubic meter now you see the S and L uh letters which have been designed for the test they are at the scale of the centimeter you see that the resolution is that the millimeter level and this is a picture that you can take in a couple of hours so from hours to months from cubic meter to uh cubic millimeter you have all the range of possible measurements what is for sure the two uh the the the common point of all those measurements as this is the case for the medical imaging is that what you see is not a direct measurement it is indirect measurement in the sense that you take row data and then you need the Reconstruction you need to solve an inverse problem in order to get the image okay this is not a direct Vision like uh with the microscope now the inverse problem that you have to solve is completely constrained by the physics if I take the sketch which is on the left we basically exploit three type of tracks the more energy the most energy particles in blue they cross the block of matter which is in Gray without being scattered and with the minimal loss of energy the red one the low energy particle they will be absorbed completely by the block of matter and the intermediate energy particles they will cross the block of matter but they will um undergo a scattering okay so you can measure either the attenuation of the flux so the red particle typically or the scattering of the particles the green trajectory typically and those two processes the first one governed by the energy loss per unit lengths uh of matter uh crossed the second one being uh governed by the so-called multiple column scattering those two processes are well constrained well known they are well documented and there are plenty of measurements that have been done on them and this is basically the physical processes that you exploit in order to solve your inverse problem so in order to allow you to go from the measured data to the distribution of matter the most probable distribution of matter that gave rise to this row data one very interesting feature of the mography of the muons is that they are available 24 hours a day seven days a week and so you can use this method to monitor the behavior of the inner part of your target this is for example a small experiment that we have done by putting a detector below a water tank there were something like 5 m of water inside the water tank and you see the blue curve here with the variation of the water level inside the water tank and you see that this variation was more or less minus one meter so something like 20% variation in Black in the middle curve you see the muon flux variation in anti-correlation with the water level of course the less water the more muon because you have less matter to stop the muon and you see the perfect anti-correlation that you get between the M flux measured and the water level what is also very interesting is that with the green curve you get the atmospheric pressure measured during this measurement and you see also the anti-correlation between the atmospheric pressure and the meon flux because of course atmospheric pressure means the weight of the air column that we have above our head and the larger this column the less muon because they are more absorbed so this is an effect that we know perfectly and we know that we have to correct for this barometric variation of the muon flux but nevertheless once you correct this uh you have a nice measurement tool for all the monitoring effects for what is inside your target the three main domains in which mography is applied nowadays are geosciences so volcanology I will give example geology hology atmosphere physics and so on so forth archaeology you have heard of the scan pyramid project and you have seen the image in the previous talk and this is also used nowadays for industrial controls non-invasive and non-destructive controls for all the uh heavy infrastructures heavy industrial infrastructures okay but I will not talk of this today an example in the volcanoes and uh we have made many experiment on on different type of volcanoes and I will focus on one of those volcano which is the suer of godal loop which is in the Lesser an and which is a vol which is known to have a very active hydrothermal system and uh this is mainly because uh the The Volcano uh Enders uh heavy rains all along the year and there is a lot of water inside the system the water gets in contact with the magma and there is a mix a mixture between steam uh liquid water and so on and so forth and this evolve in time so this is a really nice and very interesting and complicated hydrothermal system that people want to understand so the first idea was to put detectors all around the Dome and to take typical mography images and you see here the images that we get for those measurements so in red the dense zones in blue the uh less dense zones so the negative anomaly the negative Den density anomalies in in blue and positive density anomalies in Red so as expected we see that there are some big holes big cavities in the center of the volcano but we see also that there are interesting and very active cavities close to the surface which corresponds to uh the actual uh cuts of the of the volcano itself and so we have equipped this uh this volcano with up to six milon detectors uh putting them inside the fults putting them uh lifting them with the helicopter and so on and so forth so we we design a quite a robust detector that nowadays uh we we can send uh everywhere what has to be clear and this is where the link with the geoscience has to be made is that this measurements this mography measurements comes as a complement to other classical let's say standard geophysics measurement for instance in this uh Benchmark of the sufer of the guadaloop we have made three different trials to couple the measurements that we have done with the mography with other uh geophysical measurements the first one is a seismologic measurements that has been done with the geofon at the summit of the volcano and we have seen that here there was a the time coincidence between a sharp increase in the muon flux in one of the direction of the of the detector the red curve and this came in coincidence with an increase of the noise inside the geophones and by reconstructing the volume uh giving rise to this noise in the geofon we find that the volume exactly corresponds to the directions of the line of sights of the muon detector so we we managed to correlate the volume the full volume of this noise generating volume inside the the Dome of the volcano so the interpretation of course is that there was a big volume and that it was filled with water and that the water uh was somehow uh leaving the the the place and so the opacity decreased and so the muon flux increases another nice feature is that mography is sensitive to the density of the medium so this is exactly the same observable as gravimetry and so you can join the analysis of mography data and gravimetry data and you can make a single Matrix and you can make a single data inversion of both data sets giving interesting features because they have absolutely not the same kernels and so you can resolve and improve the resolution of both method by making this joint analysis and this is what we have done and this is what we have obtained on the left this is the muon plus gravimetry uh joint inversion this is a slice of the 3D reconstrued Dome that we are that we have done at that time and on the right this is the electrical resistive uh tomography which has been done of the same Dome at the same altitude and you see that the large conductivity zones in the center of the Dome corresponds to the low density measured mography plus gravimetry measurements which corresponds to zones where there is a lot of water explaining the conductivity and the the density uh zones so there is a nice very nice correlation in between the two measurements and this is why I say that this mography stuff is a good complement for Geology of the geophysical measurement so this is exactly the plan that we would like to to to apply in within the pole project and I will show you an example of uh what we have done uh in another underground lab which is called monteri which is in Switzerland in Europe so Northern uh hemisphere which is something like 300 kilometers from my place in Leon and you see see here the two profiles on the top the uh pole tunnel and on the bottom the Montery tunnel which is also in Highway okay this is a tunnel for vehicles and of course the monter uh is uh not so high as the par m is but you will see that I put here the a little bit of scale the same scale to to get an ID but you will see what we have done in the monter what could be done in the uh pole project within pole project by uh making interdisciplinary measurements between geophysics and physics so this is the first uh measurements basic measurements that we have done by moving the detector all along the tunnel and by looking at the acceptance uh from different points and you see here the different attenuation curve that you get with respect to the Zenit angle which is exactly the reproduction of the Topography of the overburden so this is really the first exercise and this is exactly the first measurements that we intend to do this year within the the the pole tunnel starting from the um let's say most Central Parts where there is the largest overburden and going uh to the entrance and going close to to the entrance second stuff that we have done in the monter is to take some gravimetry measurements at the surface in the tunnel and by making the joint inversion between mography and gravimetry and you see here the geology of this mountain is very well known there is Clay there is limestone there is Mal and so on and so forth four different areas with the four different dens I ities and you see by making a joint inversion how well we can separate the four different densities of the four different areas which is uh so this is the bottom line and this is not visible neither with the gravimetry alone nor with the mography alone and only the joint inversion is uh giving the the good separation in in densities and this is really tough measurements challenging but very interesting because this is a very clean way of characterizing the the the geology which is above our head with a minimal number of measured points let's say what is very interesting also is that by leaving the detector counting for a long time you can measure the oscillation and the flux and here for example we spotted uh a huge uh increase of the flux for one months so huge increase for couple of weeks and huge decrease for a couple of weeks and this was actually correlated with what we call the sudden stratospheric warming so warming of the atmosphere then the opacity of the atmosphere suddenly decreased on a very short time scale and so the muon can cross the atmosphere very much more easily and so uh we have here an effective temperature Co coefficient which is Alpha T which is a reference in the literature and you see the measurement point that we had in red compared with other large scale experiments underground experiment like macro bino all those experiments in graso but also Ice Cube Amanda which were um experimenting the th pole and you see that with our small detector we uh were able to have a precise point which is exactly fitting the Curve of all the big experiments installed in the underground lab so this would be very nice if we could observe this stratospheric warmings from the th hemisphere so this is one of the wish that that I have so this is exactly what we want to do having uh moving the detector that you have shown just before within the ignot tunel and making those types of mography measurements all along the tunel I will skip those archaeology uh Parts sorry for this but okay this will this will be too long just I want to focus on on on a final pictures of our adventure starting in South Africa so the idea was to send uh the three plane detector okay we put this detector inside one uh big box uh because it was more practical both from a logistic point of view and for the measurement point of view because we will just measure stuff at the Zenit and so you see the detector on the right which was prepared in my lab in France then it was sent to South Africa received in Sten Bosch making a first measurement Campa campaign in Sten BOS in this in this place and then you see this on the trailer going from St BOS to you see so this is really the uh the traveling detector and meanwhile on the left I had time to just confirm that the detector is working very uh smoothly you see the so-called acceptance figure which is basically all the direction of uh of the muons crossing the detector so this is let's say a a check uh internal check of uh of the way the detector works and this this is actually very encouraging and now we are transferring the know how to our uh South African colleague in order that they take the data start the data analysis and by the end of the month this guy will move again from wwc to the inner part of the tunnel starting really uh to look at the attenuation of the muons inside the uh Ugo Tel and this is my usual conclusion you see that mography nowadays has become very popular so popular that even the New York Times devoted an full article on the subject on how to use cosmic ray particles to see inside the volcano and uh so this is basically my conclusion so stay tuned and of course this would be very nice if we could have geophysicist joining the project to start the characterization of the geology of the nice place thank you very much for attention okay maybe we should start with questions specifically to jacqu because I can imagine seeing uh chips and beer here we probably end up chatting for quite a while but uh specific questions I guess for Jac would be the best way to start if any of the geophysicists want to know of course you know um you can email him or us and get into contact quite easily yep hey uh yeah that was a great talk I was just curious um when a muan attenuates what happens to that energy does it just get uh does it just get absorbed into an um an atom or something or Yes actually this is this is completely absorbed by the matter uh we we always the this is this is a good comment we always speak of high energy physics but for sure uh this is those partic are high energy but they are also infinitism so the amount of energy at the end is really a small one so you you can imagine that the this is converted into Fons into whatever heat and this is dissipated into the matter there is also the fact that the muon itself is not stable so it can Decay and uh the muon Decay gives an electron plus two neutrinos so nutrino completely escaped the matter without leaving any track or really little and the electron is being absorbed uh quite immediately okay I see there's a hand up on Zoom from Lou ashell go ahead unmute and hi oh sorry is that better are are you still getting an echo no that's that's better yeah that's fine okay great sorry it's it's Sue web here a geophysicist um I was wondering about the um the the muon directions are you move that thing away sorry we're we're having speaker trouble the direction of the MU coming in are you you said you were able to track that are you is that sufficient um angularity to do tomography just from the direction the muons are coming coming in or does that not is is the kind of window if you will too small um to to really see that and then I guess another question was um Joel Jansen did some work in a mine um with muon tomography looking for an or body over above an or or body that was mined Out Below and I'm wondering if you see any applications for that um perhaps in South Africa yeah so uh good points so first on the direction of course we so basically the the the most abundant uh direction is the the it okay because this is the shortest past from the top of the atmosphere down to the surface and uh when you got inclination you get roughly speaking uh an attenuation law which uh goes like cine Square Theta where Theta is the Zenit angle so this is something that runs pretty well from 0 to 80° Z angle so close to the close to the Horizon and this is something that is well known and that you can simulate using Monte Carlo generator very precisely and this is your reference flux and this reference flux then gives you the amount of particles that you await inside the direction so if with your detector you're able to measure the direction precisely which at the scale of one cubic meter you can do uh quite easily then you get your answer for the for the tomography unfortunately we cannot measure much more than this because because measuring the energy of those particle would require much more elaborated detectors that are not compatible with the field operation okay so of course once we will have the pole uh laboratory and the ground laboratory install then inside we will have very nice and smart detectors and we will have calor meters we will have a magnetic field we will have whatever we want whatever detector uh runs usually at CERN for example and with this you are able to measure the energy of particle you're measure to you're able to measure the momentum you able to identify and uh make the distinction between muons and electrons and so on and so forth and you make much more precise measurements but for the time being we live with the tracks as you understood concerning this tracks you measure only the events which are above the horizon of the detector because you are detecting something which comes from the atmosphere so with the mography only you cannot see below this is for sure okay this is an intrinsic limitation of the the method you canot see below so if you want to detect an old body if you want to make application for Mining and there are already application of mining there are people looking for Uranium for example in in the Canada but you have to put your detector below so you can imagine that you have a pit or you have an underground tunnel or you have whatever you put your detector inside and you look at uh some uh or body above your head so if there is uranium in the par maintaine okay probably we could see an increase in density we could see a positive density anomaly in our data and so I think that this will give another perspective to the project but uh this was not the first goal yeah but I mean that that's a that's a question I was going to ask people yeah I mean if you're in the muab Kong mine which is 3 kilometers deep surely you could then everything isn't known above where where you are in your passage down there is does anybody know if anyone has used muons for that okay we can talk about that afterwards um there's another question the next stand up I think is from uh Anthony RIT yeah hi good evening thank you for the talk uh perhaps direct it to yourself and to to uh Professor Maro um besides the muography what other experiments do you see taking place in the laboratory I'm assuming it's not going to be a 200 million Rand um measurement of a mountain you're going to be conducting other experiments what what what what would be the purpose or what experiments could you be see doing yeah no ABS absolutely um the traditional one that's been done underground is to measure neutrinos because again neutrinos have such a small crosssection when they interact with matter that you need swimming pool size detectors and then of course you don't want um uh background so you don't want to have any of the muons the muons will be a background but you you get like two or three counts a month or two or three counts a year in some cases so you don't want any background which is traditionally the main thing why people had underground labs but borino in Italy for example made a living out of measuring neutrinos but the big new thing is to measure dark matter I mean as you probably know the astronomers are convinced that there's a lot of dark matter in the universe and there are now I don't know just in Canada in the one lab that I was in there were four or five dark matter experiments where people are in different ways measuring dark uh trying to measure dark matter at different masses and whatever the idea is that you would get um things called axons or whatever which would interact with material in some way so you have like a nuclear detector of some kind and you're looking for this effect and it's a it's a kind of needle in a high stack because you don't know exactly what you're looking for but it's really is seen by physicist it'll change the how we understand physics if it is found so there's uh endless money for those experiments so yeah I mean there are people at the at the conference that we had in January there were at least two groups who said that if you had a lab we would come and and and and and and use it would you would you would you foresee at some stage installing a a a neutrino detector I mean as you say it's lot of that depends on size and so on nutrino detectors usually need a lot of volume at the moment I think we're thinking more of dark matter such as but sorry what I forgot to say is there are lots of other things which people measure in underground labs as well people look at um uh uh biology experiments um I was quite amazed there are several biological things which get affected by background radiation like Neons as well and people are very interested in what happens when you are in environment where that is not present that's the one thing and the other one is also U measuring with hpge detectors measuring things very accurately if you take a core sample for example and you want to see how much uranium is in it then it'll be minute quantities and so you want to be able to measure that at a level which you can't do above ground because of the background so in snow lab for example there's a whole array a whole row of um uh hpg e hpge detectors um standing there measuring things people who are interested in climate change for example are often interested in measuring uh cores of various cans which have been measured so there are lots of other applications as well the impression we got that if we had a lab there would be people who would uh want to utilize it as you but as you said sorry ja as you said Robie uh it depends on on on the size of the the facility if the size is as big as one of the uh Grand sasu platform and we can do all all of this including a nutrino experiment if the size is as small as modan which is is big but small small facility then one can make nutrino physics as well as dark matter but with a limited number of of experiment that that's it I mean but what we expect what we would like to have with PO is is a facility which is close to one of the platform of grand saso so that that could be really really an opportunity to do many many things including biophysics and and seismology and whatever all the things that you you were talking about Robbie thank you yeah I mean there there is a a growth in this field China is building a very very deep uh uh underground laboratory Australia is building one especially to have one in the southern hemisphere to uh combined with a northern hemisphere modan in France there was a lot of plans for expanding it though it hasn't uh happened and uh there's the one in Andes which people want to build there so I get the impression there's a there's a need for these things okay I see another hand from Stephanie enin Stephanie thanks very much for setting this up and and especially to lumil who got a hold of you and uh got the whole thing happening apology I have a huge apology I really thought the whole thing was going to be online that's why I'm sitting at home so a huge apology that I'm not there in the office with you I'm sorry no that that's partly my fault because I didn't decide that whether I was definitely going to come up until about last week so there there was a bit of there was understandably some confusion and I know Sue who's already asked a question she's at home because she's not well and Prof Ray Durham and Prof Musa and Prof Gord all the jist were all traveling um but they were aware of the talk and so I'm glad it's recorded So we can look at it um so it's been very interesting to hear so I mean when you say you want a j phist on board what would it really entail just attending project meetings it was great to see the data that's been done in other areas including the density sorry the gravity data and joint inversions and seismic as well so I mean it sounds like a very exciting project but yeah what would you need on our side that just just a a comment before your answer rabie uh the example I took uh the man underground lab is a lab which has been designed for methodological developments in geophysics so there are plenty of uh uh let's say ongoing experiments including R&S and the new method in geophysics and the underground lab is completely devoted to this so you have tunnels you have B Halls uh you can heat up some some of the B HS for uh some application that that you that you can that you can guess uh so there are many many many small developments for small teams and all of them are developing testing uh the new methods new detectors and so on and so forth and so this this was the the my Ida first of let's say uh trying to convince the colleague of trying to to to have geophysicist involved is because there could be also uh quite a nice overview and use of this lab as a benchmark for physical methods can assume that the overburden is well characterized I I've seen that the geology is quite complicated you have faults you have a different very interesting Parts you have perhaps carti systems with water fing inside and so you we could have have uh Hydro geology also uh experiment running in this parts so I think that there could be uh a vast number of subjects uh very interesting for geophysicist and of course after this we can join the methods mography and all the the method that you know better than me this was just my my comment Robbie if you want to to add something no no thanks ja I was going to throw it in your your quot in any case I mean you all saw the the um map which I showed and I think Lum show no which um Jac showed as well of the mountain that as you can see is from is a photocopy from a journal by the engineers who built the tunnel that was written in about 1980 and it says that 1990 sorry published in 1990 and it says at the bottom uh the sort of post uh post tunnel building model in other words they found some things which were different to what they thought beforehand so I have no idea how accurate those geological measurements are the um engineering company that's been working on it now they have done some measurements but I don't know why I don't know what and I don't know how much and I doubt if they want to tell us they're very worried about IP and things like that so I'm sure that some geophysicist could tell us something about the mountain and and do something I would guess or even just comment on what is known and what is not known I mean we are we're certainly not geologist yeah I would love to add that and to answer to Stephanie uh uh question about what we what they can do what geophysicist can do now and how can they join and what for so um there are two uh two part one one is joining uh the uh the effort that is is being done with the mography group uh to characterize a mountain in view of uh building this this facility because we we want to have this characterization of the of fault or all the burden or the REM Mountain itself before we we we we we make the design of the facility and we build it so this is the first the first part and the other part is what Jack was saying um above that uh there are so many things to do in an underground lab so there are many experiments that huge offices would like to to uh to create or to build yourself uh doing in an underground lab so you will probably bring new ideas new experiment and new project uh within pole uh pole is a facility so it's just a a um I mean a tool that you will be using to do your geophysics uh projects so this is how I see uh how how you can you can add a value to this poll project by joining uh by join joining us and you can do it just now I mean you just be in meeting and the special mu or geophysics meeting like we we do today I mean it's just fantastic seminar that is has been organized today and I'm really happy with that so I'll be happy that uh we will see you uh from now on uh belonging to our project and and and do your your own task and and and uh look for for what you can do in with the poll project that is my my point of view thanks it sounds exciting yeah thank you okay thanks thanks thanks fuse fuse we now have a a colleague of yours on the atlas experiment um from the physics department at V VZ ilas S as a dad has got a question easier in the audience yes I just want to go back to the physics a bit uh you mentioned two particular interests Lino physics and uh dark Mar now Petrino I'm just wondering if the 800 meters of tunnel would be enough to actually do any kind of interesting work with nitrinos because if we speak about Cosmic nitrinos uh as the previous speaker said most of the M flux that will interfere is going to be the major part of your detector problem noise uh now the the tro that we detect underground are the so-called uh daughter uh daughter mutes when the the Theo traverses the the crust uh it creates a nuclear reaction and that creates a mune and the mune that mune is horizontal while the munes that they are your noise comes from from basically the Zenit angles and that's what why you have to go deeper and deeper and deeper so if the interest is on Cosmic neutrinos we might have a problem with the 800 Metter we might have to go to the original experiment of cop when they discover the cosmic when they discovered the cosmic nutrino which was done at 3,600 M for exactly this reason to avoid that particular noise the other thing is that um um the uh Dark Matter uh now dark matter we don't even know what we are going to be detecting uh we have a hypothetical particle that will go up to one EV uh and most probably we will have to have a a resolution of 01 EV that means that the the demands on these type of detectors in terms of of the materials that one uh uh needs uh is extremely uh difficult of course one can buy detectors and do these kind of experiments but most of these Labs from the little that I know is they are developing materials and I would be very happy if we go into this kind of game that is an aage spin of to have a material scientist in in in South Africa working on that bits has a huge team of material scientists so but can you tell me that 800 meters is it going to be enough or should we go to a mile uh that's a that's a tricky question um sure uh yeah we have we have some profile Robbie uh that was shown by uh Alani at SSP showing the position of of Po among all the other labs there something so and that was not catastrophic actually yeah I mean it was yeah most of the muons well the average muon energy is something like 3 gev but the 3G Von gets stopped in like 20 M of granite um so actually it's only the really high energy ones which we see in any case and certainly there are some things for which if you were deeper you would be better off and as you say when you're really deep then actually you you're only seeing the muons which are formed by the neutrinos and I don't think we the muons formed by m yeah yeah yeah yes you can wait at at that type of depths you can await a suppression factor of 10 to the four let's say roughly speaking with respect to the to to to the Moon flux and which is as Fus mentioned this is something that you can live with it depends of course of what you you're looking for but okay I no I mean the more depth the better in some for some things but there are lots of things which can be done too in one which is 800 me exct of course it's 800 M of rock so it's more than that water equivalent which is is 300 yeah yeah yeah so Elias you have I have put in the chat a link to our Symposium in January that was held in South Africa at DLo and uh you can see there all the talks and uh all the I mean all all your question will be answered I believe but then you are really welcome to to join because yes we need people who who who are how would say that a more engineering material physics and making Innovation creation and all these things this is what is happening in the northern part of of this uh this Earth so people are working to to to build the most uh uh the most uh fantastic instrument to to to get a hint of dark matter or whatever so and then this will will increase also the skills the expertise and and you you know all the spinoff behind for South Africa so this is also our goal okay I think we should wrap up but yeah it's just amazing how nuclear physicist have managed to measure things you know with channeling for example where things which you would have thought would be impossible to measure people come up with the most amazing things okay I I think we should wrap up now uh um it's getting uh we've gone well well over time thanks very much jacqu I think that was an excellent introduction to the people here and as faru says I should send an email with a link which you can send to the other people which which uh gives all the talks that took place at the Symposium which we had in January at the tunnel there's this the clu of Lodge just outside the tunnel that'll give people a good indication of various things that people were speaking about like the um uh biological measurement and things like that and then the other thing Robbie please collect all the uh the people willing to join us all the emails so we will add them in the in this mailing list so they know all about the project and and can can join the task forces and and all all the the meeting that you are doing uh yes and please will you send me a copy of everything you shared in the the chat so sure yes yes thank you very much thanks thanks very much bye Robbie see you thanks guys thanks thanks