STFC-RAL-CR03: A.
STFC-RAL-CR03: I was asked to give this because I was supported to go to the conference and present this, however, I had 10 min
STFC-RAL-CR03: at the conference here. I have more so. It will be much more than only about commission. I put a lot of emphasis about
STFC-RAL-CR03: introduction to this effect. We'll let you know what is this all about, and how this is important, for dark matter searches
STFC-RAL-CR03: alright who who we are. So this is a small collaboration with 35 participants, businesses and engineers from about 40 institutions across
STFC-RAL-CR03: 6 Congress. It is heavily supported by the Isis Nile team
STFC-RAL-CR03: and our trial. We combine epid technology and Isis. Technology
STFC-RAL-CR03: is genuine provider engineering, capable to design
STFC-RAL-CR03: the detector in the shield. And here you have pictures from several meetings already had
STFC-RAL-CR03: so far through our.
STFC-RAL-CR03: So it's led by Pbd and video college funding. And here you can see funding agencies that provide support for this project. So in in the UK. It is funded by Sdf
STFC-RAL-CR03: through zoom futures R&D for future other other experiments.
STFC-RAL-CR03: Alright. So the outcome of my presentation is as follows, I will talk about media effects. and why it is important. In dark matter surges. I will say a few words. What do we know so far about the effect?
STFC-RAL-CR03: Then I will talk about we got in nuclear scattering and as well how this is being
STFC-RAL-CR03: searched in different media media. So we are not doing experiment which actually is trying to find it.
STFC-RAL-CR03: Then I will talk about first science run.
STFC-RAL-CR03: and with conclusions. Alright, let me start with with the obvious.
STFC-RAL-CR03: So this is
STFC-RAL-CR03: a picture showing how liquidism on Tpc works. So this is dual phase, and it comes from like Zeppelin, the current most sensitive dark matter. Experiment deployed in South Dakota
STFC-RAL-CR03: and what we are trying to see is a signal coming from
STFC-RAL-CR03: dark matter or neutron, which is well neutral, and we try to see as one signal, and this to signal coming from the first installation and solar organization
STFC-RAL-CR03: of the charge which it drinks upwards and goes into the gas phase, where it produces a still signal
STFC-RAL-CR03: by Xenon, well produces a lot of light and as well, is a very dense medium. So it provides very good self shielding.
STFC-RAL-CR03: By looking at the light produced and the top we can localize it with very high accuracy. In this way, by the time difference between the signal, this one and this 2 we can, we can have a depth which provides full 3D. Reconstruction of of event.
STFC-RAL-CR03: Alright.
STFC-RAL-CR03: So let's now go
STFC-RAL-CR03: little bit deeper. So what happens reading here when
STFC-RAL-CR03: the neutral, portable or so this can be interact with the 0 happen.
STFC-RAL-CR03: Well.
STFC-RAL-CR03: it can produce 2 things. You can produce either nuclear recoil or electron recoil. So everything which produces electron recoil is associated with background, and anything which produces
STFC-RAL-CR03: Nupia recoil
STFC-RAL-CR03: can be potential signal. I say potential. Because, as I said this. we want this to be a wimp? Would you like a massive particle which is charge neutral? But this light can be neutral.
STFC-RAL-CR03: and I want to now focus on really what is happening here. where a new struggle project file interacts with the nacon. Well.
STFC-RAL-CR03: until now, we thought, well, it's only nuclear recoil which can produce the signal.
STFC-RAL-CR03: But maybe not
STFC-RAL-CR03: so. This is very simple
STFC-RAL-CR03: description of what's going on. So we have a wave or a neutron. I will be stressing, because this is main source of violence
STFC-RAL-CR03: with the velocityv which hits our nucleus. Then it's cutters off
STFC-RAL-CR03: and disappears because wimps doesn't interact. Often we assume interrupts only once, and then we have no Pr record.
STFC-RAL-CR03: and that's what we want to capture. It produces a signal which we want to see.
STFC-RAL-CR03: and of course the signal depends on the energy of the of your recoil, and as well
STFC-RAL-CR03: threshold that we have in our detector that is imposed by the detector technology itself. So here's some simple equation, an example of if mass of the dark matter, part goes 100 Gv. And the mass of the look closing Xenon is 1, 3 one Gv.
STFC-RAL-CR03: The velocity which transfer from understanding of our velocity in the galaxies 220 per second, the energy that we can expect to see
STFC-RAL-CR03: very little if you're saying that detector
STFC-RAL-CR03: contains 10 tons of of living zinc.
STFC-RAL-CR03: So that's simple, very simple assumption. We look only at what is happening. Would it be nuclear recoil so far was the only source
STFC-RAL-CR03: of the signal that dark matter experiments were looking at.
STFC-RAL-CR03: So let's now give a little deeper. So let's let's think about the simple dual electron. When a neutral project pile are matter of neutron hetero nucleus.
STFC-RAL-CR03: and what we can expect to see
STFC-RAL-CR03: well.
STFC-RAL-CR03: even the velocity of the neutral pile, let's say, is much smaller than the velocity of the electrons.
STFC-RAL-CR03: Apple will remain in its ground state. Nothing fully happens.
STFC-RAL-CR03: but if the
STFC-RAL-CR03: energy of the intro protocol is high
STFC-RAL-CR03: and therefore recoil receives high speed, high momentum.
STFC-RAL-CR03: we may expect us. We actually separate
STFC-RAL-CR03: nucleus from electrons. It becomes free.
STFC-RAL-CR03: and therefore, if they become free, they may carry some energy which, in addition to nuclear recoil, we may actually see in our detector.
STFC-RAL-CR03: I'm showing this
STFC-RAL-CR03: because
STFC-RAL-CR03: I can. I want to show that we may expect
STFC-RAL-CR03: one electron, or maybe 2 or more
STFC-RAL-CR03: did something. Yeah, the top button says, control. L, I'm afraid.
STFC-RAL-CR03: Alright. So
STFC-RAL-CR03: what effects we can expect as a function of the nuclear recoil speed.
STFC-RAL-CR03: The higher it gets, the more perturbation we expect to see from an atom. So we we may have single organization. We may have excitation. We may have both.
STFC-RAL-CR03: or maybe even have double organization. All depends on the nuclear record speed.
STFC-RAL-CR03: I'm stressing, say this because
STFC-RAL-CR03: with the TV generator and even Dt generator, which produces Mev or Mev tens of Mev neutrons, we may expect to see this effects which are maybe not relevant to dark matter, because dark matter
STFC-RAL-CR03: works in the regime of nuclear recalls of very small energies. However, Miguel, experiment is not about probing Miguel effect at
STFC-RAL-CR03: the energy level that is relevant to dark matter. It is to observe it
STFC-RAL-CR03: for the first time. So I'm going to tell you why we want to do it, and why want to do it in a most favorable environment in order to detect it for the first time.
STFC-RAL-CR03: Alright. So why, this is important for dark matter.
STFC-RAL-CR03: Normally, in our other experiments we would show a plot in which we show counts per kb. Per kilogram per day as a function of the of the energy.
STFC-RAL-CR03: The Lutherans. So let's say there's a threshold deposed by the detector. and we want to see whether our sensitivity
STFC-RAL-CR03: actually reaches events for a certain mass
STFC-RAL-CR03: of of whims.
STFC-RAL-CR03: So normally, we would have, let's say, for one Gb, in Xenon normal nuclear scattering this kind of curve
STFC-RAL-CR03: of the rate as a function of the energy which you can see is much, much below what detector can actually observe.
STFC-RAL-CR03: But if we have an additional electron, the situation changes.
STFC-RAL-CR03: This electron carries extra energy which
STFC-RAL-CR03: it is shown here. You have some peaks related to shells of the atom.
STFC-RAL-CR03: and then at certain energies. electrons from more energetic shells become visible through.
STFC-RAL-CR03: Do so bye.
STFC-RAL-CR03: And as you can see, this electron actually gets into the range where the the detector can see it. And this is the most important part of it.
STFC-RAL-CR03: Thanks to this detector, which was insensitive to low mass wings
STFC-RAL-CR03: can apparently be sensitive. Thanks to this help
STFC-RAL-CR03: for free. We don't have to do much. We just have to be patient.
STFC-RAL-CR03: You can see it
STFC-RAL-CR03: always.
STFC-RAL-CR03: So this is well understood, and it can be calculated through quantum mechanics. So this is the Ma matrix element that one needs to calculate. You can see the wave functions of the atomic electrons in the bound state on the left, on the right
STFC-RAL-CR03: Describes the final state upper, which include every possible state, including the citation on this ionization, double analyzation, the all the combinations, and where we easily nuclear. So it strongly depends on this nuclear.
STFC-RAL-CR03: we can actually
STFC-RAL-CR03: probe having 2 generators, Dd and Edd and Mile
STFC-RAL-CR03: alright working with this matrix is actually very complicated. And even, it's more complicated. Or when one goes to heavy elements there are a lot of electrons.
STFC-RAL-CR03: So first, which has been done by Eva in his recent paper, there is the Dipole approximation what this exponent is
STFC-RAL-CR03: replaced by a linear linear expansion of the B, which means you can calculate probabilities
STFC-RAL-CR03: to V squared, which not necessarily fit
STFC-RAL-CR03: well at higher energies of the nuclear recoil. So in the legal project we have a group of
STFC-RAL-CR03: theorists. and they they calculated fully
STFC-RAL-CR03: and came with interesting conclusions.
STFC-RAL-CR03: Alright. So, as I said.
STFC-RAL-CR03: we might have single anization double anization current state of art in terms of theory. Predictions.
STFC-RAL-CR03: works in this regime where the probability is proportional to V squared with the this diaper approximation. Now we have extended model, which shows us what is happening with probabilities in terms of single and double ionization
STFC-RAL-CR03: to higher extending to higher energies. That's what we want, because we are using
STFC-RAL-CR03: generators providing high energy neutrons
STFC-RAL-CR03: in terms of probabilities what we expect
STFC-RAL-CR03: in terms of seeing electrons, and how often they are being emitted from the nucleus. So here you have configuration probability, configuration for electrons of different shells, and this is for lower energies, medium energies, and higher energies. And you can see different attacks starting kicks off
STFC-RAL-CR03: and depending on the energy of the nuclear recoil. What is important here to well for the student take from this is that
STFC-RAL-CR03: we deal in Emilia Experimental, which I'm going to and describe it with CF. 4 gas. which is a molecule.
STFC-RAL-CR03: However, all the calculations so far are for a single atom, fluorine, or carbon, for example. So the question is.
STFC-RAL-CR03: is the middle effect going to be the same in terms of observable in molecules here for
STFC-RAL-CR03: the same as in single separate atom of carbon and fluorine. So of course, there are different shells.
STFC-RAL-CR03: and what we are trying to see we are going to
STFC-RAL-CR03: detect high energy electrons emitted from CF. 4, which actually comes from
STFC-RAL-CR03: one s. A. Which is
STFC-RAL-CR03: inner shell, and the inner shell in molecules are not shared between the atoms.
STFC-RAL-CR03: it's not yet published. There is a paper now which shows clearly that wave functions for CF. 4
STFC-RAL-CR03: inner shells are the same as for inner shows or
STFC-RAL-CR03: separate carbon and fluorine. So
STFC-RAL-CR03: we are good.
STFC-RAL-CR03: Alright. Why, Migo? Well, it comes from Archimedeo Migo, who
STFC-RAL-CR03: made first calculations in 1 39, and but published this in this paper, which is in in Russian. which says.
STFC-RAL-CR03: and then he published another paper in 41, which
STFC-RAL-CR03: and it's in English which says about this effect, in
STFC-RAL-CR03: would that be the case? I'll find us, because, you know.
STFC-RAL-CR03: there's there is nuclear equality in in in the case. So there were 2 first political papers and then
STFC-RAL-CR03: actually read that effect. Don't observe.
STFC-RAL-CR03: In alpha decay is beta decay, positron decay, but never in nuclear scattering.
STFC-RAL-CR03: So, as I mentioned, the the effect has not been observed in alpha decay, and this was done in polonium and plutonumlicase. Alpha decays, and the measurement was about measuring X-rays, which were associated with Alpha particle emission
STFC-RAL-CR03: and X-rays were emitted because
STFC-RAL-CR03: middle electron was leaving one of the shells. And then there was automatic conversion and eating X-rays.
STFC-RAL-CR03: Associated with the emission of electron. So that's
STFC-RAL-CR03: alpha decay. Well, Miguel, affecting alpha decays, had been observed for the first time. It has been observed as well in Beta and Beta plastic case in heavier elements.
STFC-RAL-CR03: using ion truck and then coupled to a time of light. So anything changing the
STFC-RAL-CR03: ionization level of atoms
STFC-RAL-CR03: through emission of electron would change the the number here, and therefore change the time of like the species.
STFC-RAL-CR03: And by this meet. That effect has been observed in Beta metaplas decay
STFC-RAL-CR03: coming back to
STFC-RAL-CR03: affecting nuclear scattering.
STFC-RAL-CR03: There were many attempts, but never, never confirmed its existence in in nuclear scattering. So we tried to do it for the person
STFC-RAL-CR03: alright. So this is a feature of.
STFC-RAL-CR03: or Telugu, and some excerpts of of books and publications that actually mentioned this. And even
STFC-RAL-CR03: in London lives quantum mechanics you have problem to solve, which is exactly about, I mean gun effect. So it's not like, has been forgotten. People knew about it. And there are many publications actually
STFC-RAL-CR03: solving this problem without quoting that this has been already predicted by Academia in 9 39,
STFC-RAL-CR03: right? So in
STFC-RAL-CR03: 2,017, in 2,017,
STFC-RAL-CR03: Masaki wrote, even published a paper which
STFC-RAL-CR03: made miggle effect brought Miguel effect into dark matter. Researchers, I mean this triggered
STFC-RAL-CR03: focus of all dark matter experiments on this effect. So since then it has 200
STFC-RAL-CR03: citations
STFC-RAL-CR03: and almost all dark matter. Experiments now claim sensitivity to low mass wings. Because of this effect.
STFC-RAL-CR03: however, only based on theoretical predictions without any experimental verification.
STFC-RAL-CR03: So these are the plots from publication when everything now
STFC-RAL-CR03: goes into low low Mass whims saying that yes, this curve covers sensitivity, using
STFC-RAL-CR03: what does it mean for Xenon experiment. Well, it means that this is the the limit plot that normally usually dark matter experiments present their results or sensitivities.
STFC-RAL-CR03: But this area of of sensitivity to low mass wings was always
STFC-RAL-CR03: reachable only by low mass elements.
STFC-RAL-CR03: If
STFC-RAL-CR03: that other experiment uses middle like Xenon, then this area is no more, only restricted to to elements like like this. This is good.
STFC-RAL-CR03: of course they use metal, too, and they go even further.
STFC-RAL-CR03: Alright. So let me tell you now a few words about
STFC-RAL-CR03: other projects that we do
STFC-RAL-CR03: which try to see legal effect in different media. So
STFC-RAL-CR03: I'll talk about Double Face, Nicolas in an experiment.
STFC-RAL-CR03: high pressure.
STFC-RAL-CR03: and the low pressure which is, which is us so liquid. Xenon. So the the medium is dense.
STFC-RAL-CR03: So whatever happens. he's very
STFC-RAL-CR03: condense, whatever happens in the interaction point.
STFC-RAL-CR03: nuclear recoil electrons, X-rays. Everything is
STFC-RAL-CR03: stop in the proximity of the interaction from.
STFC-RAL-CR03: So this is schematic of der apparatus. This is experiment searching for visual effects at the level related. What relevant to dark matter searches at Livermore, so they use Dt. Generator, which is
STFC-RAL-CR03: which is Sean's bulk.
STFC-RAL-CR03: Here there is a lot of water to shield it, and then there is the detector, and they look
STFC-RAL-CR03: at scattering at very specific angle
STFC-RAL-CR03: is for 50.4 degrees, which is which comes from here, where the elastic scatter cross section is the highest for for Xenon. So by this they want
STFC-RAL-CR03: to get as many media events as possible.
STFC-RAL-CR03: This is double-faced genome, so they are looking, as I showed you at the beginning for S. One and S. 2. Signal, and the bands for the nuclear recoil and electron recoil are very well defined.
STFC-RAL-CR03: However, it's not easy.
STFC-RAL-CR03: So this is the experimental. You can see water
STFC-RAL-CR03: shielded in blue
STFC-RAL-CR03: the generators inside, and then there's a Colin maker, and this is the array of what the multipliers have in this specific angle.
STFC-RAL-CR03: Here is the the detector
STFC-RAL-CR03: position of the automotive virus is different. There was only one at this given angle. Now it has been replaced by
STFC-RAL-CR03: at a an array so they can increase the rate of events. No, of course, there are detectors based on
STFC-RAL-CR03: in the setup.
STFC-RAL-CR03: So they're looking for
STFC-RAL-CR03: extra energy which comes from not only middle electron, because it's very small, but from X-rays coming from algebra and anchov in Xenon.
And normally you would have 2 bands
STFC-RAL-CR03: which covers nuclear recoil
STFC-RAL-CR03: and electronic colors, which is here and somewhere in between, you would expect to see enhance of events related to media event.
STFC-RAL-CR03: So in this, this shows you final results of
STFC-RAL-CR03: what we'll see from our shell and and shell. And at the moment
STFC-RAL-CR03: they don't see this effect, they see that the number of of events observed and backgrounds is kind of similar.
STFC-RAL-CR03: and the same is for for for the end show. So this inconclusive this has been published recently, 2 weeks ago, and of course, now the we are on the spot because everyone is, is.
STFC-RAL-CR03: is is waiting for us, whether you know we don't see it too, or we save and
STFC-RAL-CR03: and try to answer the question, why, in New Zealand this effect is not.
STFC-RAL-CR03: It's not being seen.
STFC-RAL-CR03: As I said, everything happens in a very proximity in a very small space
STFC-RAL-CR03: of the interaction point, and
STFC-RAL-CR03: what is possible reason of not seeing it is that electrons from mingle actually recombined with ions from the nuclear recoil, and the effect is, and so kind of cancelled.
STFC-RAL-CR03: The other experiment is with the high pressure argon and high pressure
STFC-RAL-CR03: Xenum.
STFC-RAL-CR03: but not very much high. I mean high enough
STFC-RAL-CR03: to have a decent rate of
STFC-RAL-CR03: neutrons interacting with either Armon or or Xenon, but then allowing X-ray, which is emitted after legal organization from a shell
STFC-RAL-CR03: to be captured in the in the proximity in some distance from the nuclear recoil
STFC-RAL-CR03: production point, and therefore they are looking for 2 blobs that happens at the same time with the the energy of the second one, which is characteristic energy of the X-ray emitted by Xenon or Argon.
STFC-RAL-CR03: This is this is very neat, very interesting way of of detecting it. And
STFC-RAL-CR03: II don't have a picture of it. So this is happening in Tokyo, and, as I was told, the the run is is planned for for January next year. So there's a lot of pressure on us as well.
STFC-RAL-CR03: to be to be still competitive.
STFC-RAL-CR03: All right, let me now start talking about the middle experiment.
STFC-RAL-CR03: We work in low pressure gas, and we want to
STFC-RAL-CR03: perform an ambiguous measurement and ambiguous. I mean. we want to detect nuclear recoil and electron. we want to see them both. So when neutron interacts with the nucleus, it creates nuclear recoil.
STFC-RAL-CR03: and there is a swell
STFC-RAL-CR03: with low probability. But there is an emission of an electron and both nuclear recoil. And this electron will create trucks.
STFC-RAL-CR03: And the idea behind this experiment is to capture both drugs.
STFC-RAL-CR03: So this is very different to what other experiments do.
STFC-RAL-CR03: So we we want to use 50 tour Cfo 50 tor is
STFC-RAL-CR03: picked because it is still a bit of mass
STFC-RAL-CR03: to create a target for neutrons to interact with, however mean free path for 2.4 mev. Neutrons in our cf. 4 is half a kilometer. So we have to work with a very intense source
STFC-RAL-CR03: to still have some
STFC-RAL-CR03: rate of events looking for a rare event that happens even a bit rarer.
STFC-RAL-CR03: So 54. It's not dense
STFC-RAL-CR03: that will not allow low energy electrons to fly and create detectable truck, because, as I said, we want to image it. We want to see it, and therefore this, this pressure must be such that it creates trucks that you know of a millimeter size.
So here you have ranges
STFC-RAL-CR03: as a function of of energy, of fluorine, carbon as well electrons.
STFC-RAL-CR03: And we talk about
STFC-RAL-CR03: threshold that we set to the experiment that we want to see formula on the electrons.
STFC-RAL-CR03: What
STFC-RAL-CR03: comes with it is electrons and nuclear recoils have very different D over Dx. So here you have D over Dx as a function of the distance, not as a function of energy. Normally we would show. But this is a function of distance.
STFC-RAL-CR03: And here I want to show that electrons which are at the bottom.
STFC-RAL-CR03: They have very low D over Dx.
STFC-RAL-CR03: Comparing to nuclear recoil, which are induced by neutrons from DVD. Which means I have much, much more charge created in the detector from nuclear recoil. Comparing to the Nanator.
STFC-RAL-CR03: I have a swell different profile of energy. Loss which means for nuclear recoil. There is more energy deposited at the beginning of the truck and less at the end, which is opposite to electrons. There is less energy deposited at the beginning of the truck and more energy at the end.
STFC-RAL-CR03: So this is a very good discriminant against the background.
STFC-RAL-CR03: We had to understand what is the electron spot transport in the 50 tour. So we wanted to have first of all, the lowest diffusion, because if the truck happens, the electrons like to go sideways. And this is depends on the electric field. So actually, we wanted to work the dip of the diffusion. So when, Hello.
STFC-RAL-CR03: ionization electrons are being collected by the amplification stage. We want to keep the diffusion up to minimum.
STFC-RAL-CR03: We want to work at high amplification
STFC-RAL-CR03: to boost the signal, but as well, we don't want to have loss of electrons through attachment coefficient. So everything had to be
STFC-RAL-CR03: taken into account in the design of the experiment.
STFC-RAL-CR03: All right. This is quite a complicated plot, but it shows
STFC-RAL-CR03: the double differential rate of the nuclear recoil carbon and fluorine from dB, here you have the energy. Here you have the scattering angle.
STFC-RAL-CR03: and this takes this to account with calculation of the probabilities of middle electron emission.
STFC-RAL-CR03: So
STFC-RAL-CR03: summarizing from Dd. Source, we would
STFC-RAL-CR03: expect to have about 9 midnight events per day. and if we use Dt. Source, we would imagine we would expect to to have 30 megal events per day.
STFC-RAL-CR03: This was with some assumption that our Dd. Generator has very high flux. We we learned that it doesn't.
STFC-RAL-CR03: So we have to just
STFC-RAL-CR03: take more data.
STFC-RAL-CR03: We use
STFC-RAL-CR03: different detection. Well, different detectors in in our experiments we have Pmd
STFC-RAL-CR03: which we use to detect primary light and secondary light coming from the first amplification. Stage, which is gas electron multiplier. We use the camera, which is on the other side, which sees the light from the second gem. So the light which is coming downwards is detected by the camera and you is used to create an image. Here you have an example of nuclear recoil and electron comes from simulation. That camera would see.
STFC-RAL-CR03: And as well. We have
STFC-RAL-CR03: charge collecting electrodes here underneath of the jam which are made of indium tin oxide, which are transparent to light.
STFC-RAL-CR03: so they are deposited on the glass.
STFC-RAL-CR03: and therefore light which is created in the jam can pass through, and at the same time anonization charge which is created is collected by Ideo, which gives me the finding.
STFC-RAL-CR03: So 2D. Information comes from the camera, and the third coordinate comes from the timing when we reconstruct the signals induced on the Ito strips.
STFC-RAL-CR03: So here again is example of
STFC-RAL-CR03: simulated event with nuclear recoil. And electron, this is what Ito would see each strip. This is what the camera would see, and then we can stitch 2 together in order to to have a 3 reconstructed event. And, as I said, an electron and elect nuclear recall, they have different energy density. The position. And they're
STFC-RAL-CR03: brack curve would look like this which this is this coming from an electron, the analyzation. Highest optimization is at the end of the track
STFC-RAL-CR03: which is shown here. And this is nuclear recoil with the highest ionization density at the beginning of the truck.
STFC-RAL-CR03: This is simulation.
STFC-RAL-CR03: Okay, this is the real thing. Is it quite compact? Is 15 cm by 50 cm. Here, inside that it sits in the cube, which is 30 by 30 by 30.
STFC-RAL-CR03: As I mentioned, we use 2 stages of amplification which are here. This is glass gem coming from Japan is 550 micron thick is metalized on both sides. So when you apply electric field
STFC-RAL-CR03: of a voltage. Then you create electric field across the holes. You see magnification of the holes.
STFC-RAL-CR03: So the Od of the whole is 170 microns each to 180, and it covers area of 10 by 10 cm, and the total game can go up to 100,000 are using those 2 to gems which is good enough to to detect low energy. But, as I said, nuclear recoil creates almost 10 times more
STFC-RAL-CR03: ionization charge, and the ionization densities higher than an electron
STFC-RAL-CR03: which requires high dynamic operation of this device, which is challenging because this is gaseous detector, we can easily reach so-called weather limit. When the size of the avalanche is 10 to 7 electrons, and it creates a spark.
STFC-RAL-CR03: So
STFC-RAL-CR03: sparks are not good for microparten detectors. Usually a spark or a series of sparks can damage this
STFC-RAL-CR03: as and
STFC-RAL-CR03: we're quite likely with this development of the glass gems, it looks like they are very robust. We can work with a certain rate of sparks without actually compromising
STFC-RAL-CR03: beats for performance.
STFC-RAL-CR03: You have a picture of Ipo strips, so they are here at the end. They are metalized with chromium aluminium for bonding connection to the flexible cable which reads which transfers signal
STFC-RAL-CR03: to the da queue
STFC-RAL-CR03: electric field in the Tpc has to be as uniform as possible.
STFC-RAL-CR03: Here you can see the gap between the cathode and the first gem there is. There is 12 field shaping rings, every centimeter to maintain uniform electric field. They cannot go all around, because here there is a beam which goes through, and if we had this rings all around, they would act at least up 2 sides as additional target for neutron, so we had to make them only partial on the sides of the team.
STFC-RAL-CR03: but nevertheless the field is quite uniform inside of the active volume.
STFC-RAL-CR03: Here, again is a picture of the IQ strips
STFC-RAL-CR03: we use for the camera. We use low noise, fast camera from from Hamas. So this is their latest model.
STFC-RAL-CR03: We can work with about 150 frames per second with extremely low noise, which helps very much in this experiment, and the Pmt. Which comes from Lz
STFC-RAL-CR03: Jemma.
STFC-RAL-CR03: As I said.
STFC-RAL-CR03: you have metalization on both sides. When you apply Dv. Across the field inside of the hole is high enough for cancer simplification.
STFC-RAL-CR03: We work with about 550 volts, across which creates field of 10,000 volts per centimeter, and in single gem it gives a gain of about 150.
STFC-RAL-CR03: We have dedicated gas system. This allows us to deliver gas
STFC-RAL-CR03: single gas for 2. We can mix it here in the cylinder is big enough for 3 loads that we can use in the chamber.
STFC-RAL-CR03: We plan to change the the load every 6 h. But we notice that the chamber itself is so clean that actually we don't have to
STFC-RAL-CR03: purge and feel very often, which actually is quite painful in denial, because we cannot keep high pressure cylinder inside of the bunker, so is to stay outside, but from our experience we can see now, then, the outgassing is so low, and purity of the gas is so good at one load of the of the sugar is is good enough for for several days.
STFC-RAL-CR03: Okay, Dq, Dq is quite complicated.
STFC-RAL-CR03: Because we have so different ways of of reload. We have. Pmt, we have Ito, and we have the camera all have to be synchronized because we want to capture one event through different channels and then
STFC-RAL-CR03: be able to reconstruct it.
STFC-RAL-CR03: So the camera actually to be when it works at full speed. it has to is has to work continuously. There is no trigger
STFC-RAL-CR03: while the Ito we want to. We want to trigger, and it comes from the Pmt.
STFC-RAL-CR03: So we have to make sure that we understand which frame corresponds to a given waveform. So in order to synchronize it. You have T. 0.
STFC-RAL-CR03: The camera when it or the the Dq. When we start, sends a pulse to an led
STFC-RAL-CR03: and led, is seen by the camera.
STFC-RAL-CR03: and this is rolling shutter, which even better tells us what was the timing for the camera when the led was triggered by by the duck, and therefore this gives us T. 0 for the entire run.
STFC-RAL-CR03: Since we know what is the time, the exposure time, then then we can. We have a whole history.
STFC-RAL-CR03: Unfortunately, the Dq. Is is old.
STFC-RAL-CR03: and it has 3 3 ms to the next time, so we have to make sure that this is captured too, and then we have. Therefore we have Fpga clock, which records all the triggers that
STFC-RAL-CR03: triggered the chamber. But the beak you was not able because of the next point.
STFC-RAL-CR03: Alright is our first beautiful events.
STFC-RAL-CR03: showing you 5.2 heavy photo electrons from fluorine.
STFC-RAL-CR03: So these are the images. And you can see the dots which corresponds to individual holes in gems. Moreover, in fluorine you can see as well
STFC-RAL-CR03: 700 Ev oga. Electron so this tells you how this technique is powerful in order to see law and regiments.
STFC-RAL-CR03: It looks great. but actually we cannot use it in our experiment here. We have such a beautiful picture because we push the game
STFC-RAL-CR03: to have this bright image. But if I push game
STFC-RAL-CR03: with nuclear recoil.
STFC-RAL-CR03: nuclear recoil starts, create huge size of avalanches which leads to sparks.
STFC-RAL-CR03: This is the image from the Ito strips. We can either individually
STFC-RAL-CR03: analyze each strip, or we can use this as an image and and treat the same way as we treat images from the camera.
STFC-RAL-CR03: We already tried to. Mix argon with argon, for example, because we want to look for Migdal in other species not only carbon and fluorine, but as well in noble gases which are more relevant to dark matter searches, and we can see that it works beautifully as well, with the addition of of
STFC-RAL-CR03: and noble gases. Here, for example, you're going to see Ozia electron from from Harlem.
STFC-RAL-CR03: This is our background, so I call them deep sea monsters.
STFC-RAL-CR03: So when we don't use any source, we see higher energy, I think Delta raise from Muons, which which pass our well experimental hull, and produce electrons and deltaaries.
STFC-RAL-CR03: So they are not dangerous
STFC-RAL-CR03: when we work with high gain, but they become dangerous when we work at low gain, and we see only parts of them. and they meet me grow energy electrons. So if they happen at the same time as nuclear recoil
STFC-RAL-CR03: in the same spot. They look like Miguel. However, the rate is very low, and they are not dangerous.
STFC-RAL-CR03: In order to know whether this detector can work with the Dd. And Dd. Generators. We wanted to mimic
STFC-RAL-CR03: high energy nuclear recoils with from Dd and Dd. Where the highly analyzing alanising particles coming from reductive sources.
STFC-RAL-CR03: So here you have examples of fission fragments coming from California source. So these are extremely high energy node and palladium, 80 mev. And 105 mev. That we
STFC-RAL-CR03: try to
STFC-RAL-CR03: say tune with energy in terms of distance where they enter into detector. So with the energy, density, deposition. They mimic nuclear recoil's end point of nuclear recoil from de. And what we notice that
STFC-RAL-CR03: each of them actually was sparking, which tells us. This technology or this arrangement of glass gems
STFC-RAL-CR03: is not suitable
STFC-RAL-CR03: to work with high energy neutrons. So therefore, we can use at the moment well, show you.
STFC-RAL-CR03: Dd generator, which creates lower energy neutron center for lower energy coils.
STFC-RAL-CR03: Yeah. So all of us are very good to mimic nuclear calls from Midi. At the same time we use item 55 source, which creates low energy electrons, and you can see no sparks
STFC-RAL-CR03: and detector can have
STFC-RAL-CR03: dynamic range large enough to be able to see me. V. Alphas! Track from Alphas! And as well.
STFC-RAL-CR03: Few Kvs are electrons that are coming from iron. 50 finer.
STFC-RAL-CR03: So that was actually very encouraging.
STFC-RAL-CR03: Here's example of 4. Alphas! Well, they were not. At the same time we just put them together.
STFC-RAL-CR03: But I wanted to show you that we started to see some some problems. This is one frame. This is second frame. There are some ghosts
STFC-RAL-CR03: in this camera which is very sensitive. It seems like it. Read the information of the high tens. Highly intensive
STFC-RAL-CR03: tracks remains to the next the next frame. So we have to be careful, because they look very similar to low energy electrons. So actually, we have to find where they happen and then exclude in the analysis of the consecutive frame.
STFC-RAL-CR03: This is how it looks on the Ito. There is another problem. I wanted to highlight that we have ringing on. The electronics produces an effect which is very similar to the track, so you can see 2 2 bands, but actually one
STFC-RAL-CR03: corresponds to the truck. Another one is an artifact coming from the electrons which we're trying to solve. This is spark. and we have them a lot because of the discharges in in the gas.
STFC-RAL-CR03: Alright in May we moved our setup to Nile. Here you can see the Nile Bunker in TS. 2 station
STFC-RAL-CR03: at Isis.
STFC-RAL-CR03: and there was quite a lot help of stop from Isis to help us to arrange everything inside of the
STFC-RAL-CR03: of the bunker of the bunker. I mean, we had to load everything from the top because the door is too small. and then you can see several pictures showing preparation of the experiment that mile. This is teams, my Phd students
STFC-RAL-CR03: whose thesis is unreal.
STFC-RAL-CR03: So this is how the shield looks like around the experiments. So here is the
STFC-RAL-CR03: the main chamber, and then we have 10 cm of lead to stop all the Gammas, and then we have 30 cm of plastic which break it, which stops all the neutrons and slow them down.
STFC-RAL-CR03: This is fully suited experiment.
STFC-RAL-CR03: This is what is inside the Chamber amplifiers for the Itl TV generator, 30 cm long
STFC-RAL-CR03: collimator, which has a special shape in order to shape the the neutron beam into something that gets into the active volume of the chamber which is defined here.
STFC-RAL-CR03: This is this is ready to start polish-shielded experiment gas system attached and did a generator in front of the small window of the column engine
STFC-RAL-CR03: summary of the First Science Run. We were taking data over 3 weeks. Here you have accumulation of the data in total, we
STFC-RAL-CR03: recorded about 17 million frames. we used only Dd generator. As I said, the rate was not as designed, because we we found the
STFC-RAL-CR03: a flow of the of the generator, which was
STFC-RAL-CR03: specified to deliver a very narrow beam. However, it happened, the beam is broader, and therefore, with our collimator we stop a large fraction of the neutrons that we intended to to detect.
STFC-RAL-CR03: We had as well work with the higher exposure time, because Linux, driver from Hamas didn't work very well.
STFC-RAL-CR03: Instead, we normally would work with 8 ms. But this was 20, so we were more prone to accidentals.
STFC-RAL-CR03: We performed the calibration with that 1 55 to one for the game. We noticed that the voltage across James had to be tuned every day because the gain was decreasing. And this is a fact that we don't understand it yet.
STFC-RAL-CR03: And we work with average spark rate of 7 sparks per minute, which
STFC-RAL-CR03: we again we had to learn whether this is destructive or not, but it looks like over 3 weeks.
STFC-RAL-CR03: This didn't deteriorate to the level that we were not, we wouldn't be able to
STFC-RAL-CR03: to record the data.
STFC-RAL-CR03: Half of the data is blinded. So that's for those who are analyzing the data.
STFC-RAL-CR03: So here is the history of the iron 55 measurements, and you can see that it fluctuates over the day. And then, in order to maintained again every day, we had to actually
STFC-RAL-CR03: add one volt.
STFC-RAL-CR03: To Dv. Across jams to get to the gain of the from the previous day. We don't know this. Why, we we talk to suppliers from Japan. They said that this this effect is new to them.
STFC-RAL-CR03: Okay, so this is an example of nuclear recoil. It has 4
STFC-RAL-CR03: in length and energy, about 100 kv.
STFC-RAL-CR03: This is real example.
STFC-RAL-CR03: This is another example of higher energy nuclear recoil, and you can see there is something attached to it
STFC-RAL-CR03: here.
STFC-RAL-CR03: There's as well a smudge here.
STFC-RAL-CR03: Actually, these are electrons. So
STFC-RAL-CR03: this is not me. Go. This is
STFC-RAL-CR03: and mix data when we run with the D together with iron 55 source.
STFC-RAL-CR03: We wanted to see whether
STFC-RAL-CR03: we have events. When electron happens in the same location. There's no biocoil to mimic, niggle
STFC-RAL-CR03: and learn
STFC-RAL-CR03: whether we can find it.
STFC-RAL-CR03: So this is like amygdala. Like topology. You have 2 tracks
STFC-RAL-CR03: well identified.
and they are very well
STFC-RAL-CR03: understood in terms of their energy. D over Dx
STFC-RAL-CR03: and the economic range.
STFC-RAL-CR03: We use
STFC-RAL-CR03: machine learning, object detection algorithm, which I will tell you later. and it draws boxes around the
STFC-RAL-CR03: around the trucks that he sees.
STFC-RAL-CR03: So what do we see? And electrons when we see electrons and nuclear recoil. Of course we want to know is this Migdo or not? So
STFC-RAL-CR03: the 2 electron and nuclear recoil happen in such proximity that we would say, yes, this is mingle.
STFC-RAL-CR03: but it's not only they have to happen at the same, the same spot, but as well. They have to happen at the same time.
STFC-RAL-CR03: So when we look at timing information
STFC-RAL-CR03: of this nuclear recoil.
STFC-RAL-CR03: here is what
STFC-RAL-CR03: ITOC. S. An. Electron, and another electron.
STFC-RAL-CR03: When we look at the timing. Actually, we can see time, separation between nuclear recoil and both electrons, which tells us well, the image sees this because they happen within 20 ms of exposure time.
STFC-RAL-CR03: however, due to signals induced on the idea of Ideo. I can tell you that actually they are not happening at the same time, and there is a time gap, and therefore this is not legal.
STFC-RAL-CR03: which is one of the most important part of the discrimination of of
STFC-RAL-CR03: background against the signal is the timing.
STFC-RAL-CR03: because in order to have an electron, which is
STFC-RAL-CR03: which looks like big dialectron and nuclear recoil in the same spot at the same time is extremely low.
STFC-RAL-CR03: Alright, so what do we do in order to fine to beat those
STFC-RAL-CR03: within 10
STFC-RAL-CR03: 1 million of images we use yellow? I don't know if people are using here yellow. So it's a state-of-the-art object detection algorithm. which is for you only loved ones.
STFC-RAL-CR03: And actually, it is used when the data is coming. We have Gpus in the dark PC. Which actually analyzes images as they come
STFC-RAL-CR03: and can draw boxes around every truck it finds. and then
STFC-RAL-CR03: make some analysis. I will skip, because I think the time is short now.
STFC-RAL-CR03: And in the analysis it measures the distance between boxes which are around trucks so it it can identify nuclear recoil. It can identify an electron.
STFC-RAL-CR03: But as well can tell me what is the distance in between. So we can.
STFC-RAL-CR03: That's
STFC-RAL-CR03: reduce number of of frames that have, you know, multiple boxes per per image with different distances from millions to thousands. That means something that is unmanageable can become manageable in terms of human analysis. One by one.
STFC-RAL-CR03: Okay, we do as well. Threed talk reconstruction because we have image which is twod, and the Ito
STFC-RAL-CR03: signals provide the the third coordinate. So this is what it sees. This is what camera sees. This is very interesting event. Actually, there are 2 s, there are 2 nuclear recoil. There is a main one
STFC-RAL-CR03: and a secondary one, which is being induced by the primary. So probably this is high energy fluorine. And probably this is this is carbon, which is light.
STFC-RAL-CR03: and then we stitch them together. So these are again 2 planes.
STFC-RAL-CR03: and when we stitch them together. We can reconstruct track in 3D. And then follow the reconstructed line and look at the brack curve and see what is the D over Dx. Which in this case corresponds to 2 nuclear recoil. If this is the vertex, the D over Dx is the highest where they start and then decreases as we go further away from the interaction point
STFC-RAL-CR03: alright. In my summary I want to say that
STFC-RAL-CR03: make that experiment aims to perform first, an ambiguous observation of the media effect. I say observation, because detection will come later. We had our first science run with the Dd. Generator this summer at my facility at trial
STFC-RAL-CR03: detector performed well. The state of the art
STFC-RAL-CR03: is probably one in the world which works that way in very harsh environment.
STFC-RAL-CR03: We plan well, we plan to take more data in September. We will do it in January.
STFC-RAL-CR03: analysis of the data is underway. As I said, 50% is is blinded, because if if we see it, we want to, we don't want to be biased.
STFC-RAL-CR03: Stay tuned for the results. Thank you very much.