STFC-RAL-CR03 R61: And if you are again explosives
STFC-RAL-CR03 R61: we have the amazing predictive capabilities of standard model which are the Testament to its success. And as a baseline particle physics model wherein you can see the experimental measurements, how closely they match with the 3 predictions.
STFC-RAL-CR03 R61: Now,
STFC-RAL-CR03 R61: howsoever remarkable it is, we still have unanswered questions.
STFC-RAL-CR03 R61: If we ignore some of the Lambda Cdm cosmology tensions
STFC-RAL-CR03 R61: and if we take a picture of the universe as it as it is, we do know for sure that there's a hell lot of
STFC-RAL-CR03 R61: part of the universe which we don't understand.
STFC-RAL-CR03 R61: And then we know that. Okay, there was a amount of maternity mediated in the beginning. And today there's almost
STFC-RAL-CR03 R61: no antimatter you the universe. And then we have the master Rp
STFC-RAL-CR03 R61: problem for the
STFC-RAL-CR03 R61: different parts of this. So
STFC-RAL-CR03 R61: now, building on to these problems one of the areas where, promising avenues where we can look for some of these answers is the study, and such as for the longer particles, they're there in the standard model as well as beyond. And if we take a look at the standard model, we what we are referring to the longer particles are mainly yeah. The lambdas and K shots
STFC-RAL-CR03 R61: which are not detected stable and decay within the within our our
STFC-RAL-CR03 R61: ongoing particular phase. Experiments
STFC-RAL-CR03 R61: how? Exactly.
STFC-RAL-CR03 R61: These are.
STFC-RAL-CR03 R61: Yeah. If you see, I mean here in this particular particular broad we have, the distribution where you have detector prompt, for example, W. And Z. Which are very heavy to to the stable particles.
STFC-RAL-CR03 R61: And what I want to highlight here is,
STFC-RAL-CR03 R61: When we take a look at the the
STFC-RAL-CR03 R61: proper time distribution and the proper time is inversely proportional to the decay rate, and how the decay rate is related. Here is you have the mass of the Lnp. And inversely proportional to the mediator of the infections. For example, if you have the the Z and W. Which are quite heavy, you will have
STFC-RAL-CR03 R61: the decade would be smaller, and the lifetime would be higher.
STFC-RAL-CR03 R61: So
STFC-RAL-CR03 R61: moving on we do have quite well established.
STFC-RAL-CR03 R61: Be some scenarios. Where there's a probability there's a good chance that there which can have
STFC-RAL-CR03 R61: Llps. So now, taking a look, we have the hidden sector.
STFC-RAL-CR03 R61: We have.
STFC-RAL-CR03 R61: It can be that can be a sigh or a Higgs which can dictate to 2 long live scalars!
STFC-RAL-CR03 R61: Which? within our other detectors. Then we have these heavy neutral laptops, for example, a sterile neutrino where you can have a heavier Lepton interacting with the standard model. Neutrino
STFC-RAL-CR03 R61: like particles another scenario is eggs on like particles. If you remember the strong Cp problem, and how in in the in the Qcd. It was like it it it was assume that they can be long live exons which were able to
STFC-RAL-CR03 R61: sort of stabilize that particular problem. And so but there has not been any observation of the Hr. Like particles, so there can be a scenario where you have
STFC-RAL-CR03 R61: Alp, digging into 2 photons, for example. And if you're a believer in the sushi, then yeah, they can be
STFC-RAL-CR03 R61: to believe blean knows
STFC-RAL-CR03 R61: which can, in fact, so be paying into charginos or internals
STFC-RAL-CR03 R61: for that. This good community Llb. Community work as well. There has been a recent
STFC-RAL-CR03 R61: review paper for the Lps some of these where I participated. I I put in here from that Lp community where different efforts from the different Lsc experiments had been summarized into in in with regards to such as of the lp's, and so on, and there were some dedicated ones at Lcb.
STFC-RAL-CR03 R61: where the intent of probing these and what exactly should be our reconstruction strategies for these for for studying these on this particles
STFC-RAL-CR03 R61: now, coming to the introduction of the experiment where this work has been performed, we very well know. And let's see.
STFC-RAL-CR03 R61: I think I can just skip this. we do have some members on the Lcb. In the audience here. But you know, it's a single arm forward spectrometer specialized for for studying the be physics which covers about 27 of the V Hurons produced in the power and the backward reason
STFC-RAL-CR03 R61: And covering about 4% of the solid angle. Then
STFC-RAL-CR03 R61: some of the highlights from the last lscb, run one and run 2
STFC-RAL-CR03 R61: which these results are mainly with the 900 inverse of the data and producing well, leading measurements. for example, here the number of head drones which have been
STFC-RAL-CR03 R61: which have been discovered by the lseb. But it's not just that. Out of 72 69 have been the lseb. And
STFC-RAL-CR03 R61: we do have some possibilities wherein we can have still weekly digging tetraques and pentaques, which which are waiting to be discovered.
STFC-RAL-CR03 R61: and then you have this Vs vs. Bar, mixing the flavor oscillations, the beautiful plot which has been
STFC-RAL-CR03 R61: in the new term missions the the which and then following which the this is one of the rare details in the vs. 2.
STFC-RAL-CR03 R61: You mute so the best measurement for these
STFC-RAL-CR03 R61: which was done with the physics in the run to and run. Run by and run 2. But now for the run 3. It's a new detector. It's a completely new detector where 90% of the active detector channels has been replaced
STFC-RAL-CR03 R61: and
STFC-RAL-CR03 R61: and it is it is designed to handle 5 times instantaneous luminosity as compared to
STFC-RAL-CR03 R61: the there are one. It's a there's a very nice article if you want to check it. Let's a moment just metamorphosis.
STFC-RAL-CR03 R61: Now, I want to cover in briefly, the different detectors, because, we are going to be talking about algorithms which are using detectors. So we have
STFC-RAL-CR03 R61: tracking detectors for doing the flavor physics, you need to have excellent tracking. So we have the vertex locator, which goes really very close to the interaction point. Which? Yeah, when we have. That's the silicon pixel detector with 52 planes and 42 million channels. Then you have the upstream tracker. Which is like constant detector with 4 planes right before the magnet, and then you have the upper magnet. That's it for our detectors with 12 planes of
STFC-RAL-CR03 R61: 2 into 2.5 meter fiber each. You detect the charge particles and localize the detective vertexes. Using these, then you have a magnet which is a 4 dipole magnet of 4 DM, which bends the Char Particles past, allows us to to measure some of the
STFC-RAL-CR03 R61: the characteristics such as momentum.
STFC-RAL-CR03 R61: Then you have a very good pid system with ring imagining chemical detectors before and after the after the magnet. You have the
STFC-RAL-CR03 R61: you have the Muon chambers and and and kilometers
STFC-RAL-CR03 R61: mountain
STFC-RAL-CR03 R61: looking at the computer challenge.
STFC-RAL-CR03 R61: the problem. Now for the run. 3.
STFC-RAL-CR03 R61: it's basically the biggest real time data processing challenge and if we just take a look at the rates at 40 terabits line rate of interaction, we could be producing over 150 per day, which is impossible to
STFC-RAL-CR03 R61: to store
STFC-RAL-CR03 R61: and impossible to transfer with our current current bandwidth capacities out of the detector. So
STFC-RAL-CR03 R61: so
STFC-RAL-CR03 R61: if we
STFC-RAL-CR03 R61: just so this has to be. There has to be a way of overcoming this. Then we have the Lseb ticker system. You can see this was how it was during the run to where we had a hardware trigger at L 0. We call as 0, followed by the software trigger. The problem was, we saw start seeing that at high luminosities
STFC-RAL-CR03 R61: hardware digger cannot cope with the event rates and start rejecting random events. So
STFC-RAL-CR03 R61: and this was. This is one of the reasons why this having this hardware trigger. It was needed to be eliminated from from the whole of the trigger system.
STFC-RAL-CR03 R61: and
STFC-RAL-CR03 R61: it is useless to produce more interesting events if we are unable to study them. So one of the options is that. Okay, we can just discard random events.
STFC-RAL-CR03 R61: But it's just better to be more careful than that.
STFC-RAL-CR03 R61: Instead of discarding randomly. So that's this comes the real time analysis, paradigm.
STFC-RAL-CR03 R61: So
STFC-RAL-CR03 R61: one thing is, we have the fixed bandwidth which is fixed, and we realize that if we want to store the whole of the event.
STFC-RAL-CR03 R61: Then we'll not be able to with the into the within the fixed bandwidth. We'll not be able to do a lot of physics. So if we had kept without our Rtm model, if we just keep it like, that will be the physics program which we'll be covering would be even less than 40%. What, as compared to what we would like to have.
STFC-RAL-CR03 R61: So then, it was, we have to find out a way of reducing the event, average event size size, which we which we store. And for that you need to analyze that event in the real time, and you know, only store the reconstructed objects and not the raw event itself. So if we basically increase the fraction of the
STFC-RAL-CR03 R61: the Rta. Even, sir, where the event size are smaller, we only storing reconstructed objects. Then you you can cover much more, or and can fit in within within the trigger, or for bandwidth of 10 GB.
STFC-RAL-CR03 R61: So that's why. For these reasons. We had to have a new strategy for the run. 3. What we came up with was, we have entirely new. Ha!
STFC-RAL-CR03 R61: High level trigger, one which is now based on the gpus about order of 500 gpus which are sitting on the even building servers themselves 2 gpus per even server. And then you have the high level trigger 2, which is on the x 86 servers. So it's a 2 stage software trigger
STFC-RAL-CR03 R61: to and here
STFC-RAL-CR03 R61: should be able to keep capable of pro of processing the events at
STFC-RAL-CR03 R61: at 30 megahertz. So
STFC-RAL-CR03 R61: basically, we take a, we take a look here, what we do is at the 21 level. We have the party partial reconstruction of the chart particles and tragicties with a few simple selection lines at the high level trigger, one level, and then, at that 22 level. We have the full reconstruction selection based on different decents and
STFC-RAL-CR03 R61: signatures. But the the main thing is we want to do this without reducing or affecting the fidelity of the tiger, we should be able to cover
STFC-RAL-CR03 R61: as much as possible. And in between. We have a buffer where we can store the data temporarily before. It's being processed by the high level, too.
STFC-RAL-CR03 R61: Then there are different chains where you have. This is the Rta model, where, if you have 68% of travel events we also do have to store full events, and then some other lines change for the for the deliberation.
STFC-RAL-CR03 R61: and how this is exactly implemented on the hardware level is that you have a different detector. We have 11,000 hop duplex detector lay links connecting directly to our even visual network with the Gpus.
STFC-RAL-CR03 R61: and then we have a storage buffer storage about 40 petabyte disk, and then you have the second.
STFC-RAL-CR03 R61: and I will take that, too.
STFC-RAL-CR03 R61: Now, coming to the framework, the software which runs on this.
STFC-RAL-CR03 R61: We have
STFC-RAL-CR03 R61: mainly the ha! The delicacy trigger is based on the tracking. What, exactly is the tracking, tracking deals with converting the signals from some detectors like hits and clusters into the traffic, please? Not least picking. There are 2 faces. One is partnering cognition track track fitting. And
STFC-RAL-CR03 R61: why do we need to do? Is we do we need to be able to build the detectors, measure decrease apologies which allows us to measure the momenta and then analyze the events in the real time. What we do here is that in this software, we have 3 levels of parallelization. We process
STFC-RAL-CR03 R61: the inter event level prioration, where you do a lot of computation and measuring these tracking within a event and in parallel, then you have multiple events which are being processed in the bunches and the batches on, on, on the gpus. And then you have the multiple Gpus doing this
STFC-RAL-CR03 R61: at the same time. The software is mainly as software project. It's it's a framework develop for the Lt one as a standalone project primarily developed, using cuda, as you can see. And one of the features I want to highlight here is that.
STFC-RAL-CR03 R61: we developed it with our own custom performance, portability layer. That was my work in in the, in in developing the framework where I contributed. And
STFC-RAL-CR03 R61: so you have these external base libraries. We have the code algorithms. And then we have the compiler infrastructure. Based on the top of it. We have our custom Pocon portability. Here, mainly written, all the algorithms are based mainly written in the C in the coda
STFC-RAL-CR03 R61: and you had it running on the multiple platforms, as you can see, we have Nvidia Gpus, Md. Gpus, as well as the cpus, being able to run on the same port on the multiple platforms with a very nice performance.
STFC-RAL-CR03 R61: comparable performances on each of the platforms.
STFC-RAL-CR03 R61: And so we then have this paper. Where? In 2,019 20, where some of this work was presented first time.
STFC-RAL-CR03 R61: Now, coming to the park belong little particles and tracking all this algorithm development which happened a bit. Now, I'm going to discuss was basically possible because we have this new framework
STFC-RAL-CR03 R61: where we could. we could do much more as compared to to CPU ways
STFC-RAL-CR03 R61: the software framework
STFC-RAL-CR03 R61: then.
STFC-RAL-CR03 R61: now coming to the lps. So we have them in center models and Bsm, so we see
STFC-RAL-CR03 R61: the distribution here. In terms of the sand model. We have mainly the Lambdas and K shorts in terms of. So, for example, these numbers and k short. So here you have the valu, or then, this is the region between wello and ut, and then, this is the region between
STFC-RAL-CR03 R61: the beauty in the sci fi, and so stand more particles the a lot of them of lemdas and K shorts which are important. K shorts are important for the CPU violation studies. Lem does have their own
STFC-RAL-CR03 R61: interests in terms of, because there are rare radiative decays. And there can be a lot of new physics which can be happening in the loops. So
STFC-RAL-CR03 R61: so
STFC-RAL-CR03 R61: these are the standard model. But also, if we take some of the Bsm models, for example, you can see in this plot how the decay probabilities are with respect to each detectors the. This is the distribution of the mean flight distance versus the lifetimes. And and this
STFC-RAL-CR03 R61: I want to clear. Make one thing clear here that there was no dedicated reconstruction
STFC-RAL-CR03 R61: in the high level trigger one during the run, one and run 2. So we did not had any dedicated trigger, which were basically reconstructing lambdas and K shorts and all that particular pieces in the high level trigger one level
STFC-RAL-CR03 R61: again, as we were talking lambdas and k short, so you have a decay like this where lambda V goes to lambda, where lambda decays to proton and pions, and you can have an average seat of about 8 cm. And if we take a look at how the distribution of the decays. So, for example, you have the lambda n vertex, and the K short and vertex. You would see only about 12% of the lambdas decay in the value.
STFC-RAL-CR03 R61: And only about 46% of the K shorts, a majority of them, 51% of the in terms of the them does they decay outside. So
STFC-RAL-CR03 R61: if your trigger is based on the signatures which are in your primary detector, you are going to miss these 51%.
STFC-RAL-CR03 R61: And
STFC-RAL-CR03 R61: and and I'm going to show you how it's important for doing a lot of
STFC-RAL-CR03 R61: spin which
STFC-RAL-CR03 R61: we're doing the angular measurements as well as the branching measurements how they are important for sustaining. Considering some of the Wilson coefficients in the C. 7 c. 7 c. 7. Prime claim in in this case.
STFC-RAL-CR03 R61: and maybe some of the analysis which we did using this particular can be seen for another seminar. I don't want to go into the detail at the moment. But now moving on to the Bsm scenarios. If you look at that for example, in this example
STFC-RAL-CR03 R61: where we can have a
STFC-RAL-CR03 R61: Higgs, which can be going to the 2 new Muse. You see, the the efficiency is based on the Higgs lifetime.
STFC-RAL-CR03 R61: This is so in this case
STFC-RAL-CR03 R61: the efficiencies, if it is promptly decaying, up and decaying within, leaving the mark in the wellow are like good as compared to very bad, for if it is a long lived
STFC-RAL-CR03 R61: so
STFC-RAL-CR03 R61: in this case you're talking about a dark Higgs. Higgs Prime, which can be going to the 2 Muons, and the efficiencies were very low.
STFC-RAL-CR03 R61: So
STFC-RAL-CR03 R61: before coming to how we mitigated it, let me try to again explain to you different track types. In Dial Cv, we have the bellow
STFC-RAL-CR03 R61: which basically produces the bellow tracks. Then you have the upstream tracks which go only through weather and beauty. Then you have these long tracks which have been our main physics tracks for the unemployment, and 2 which passes all traverses all the tracking detectors.
STFC-RAL-CR03 R61: and then there can be Llps or the display second divergence tracks which basically don't leave any anything in the wellow or not covered in the wellow, or only, you know, leaving the tray faces in the outside of the bellows.
STFC-RAL-CR03 R61: and so, but they can be there detected using the downstream tracking, and also then you have dedicated sci-fi tracks. But which can be there in between you have the the
STFC-RAL-CR03 R61: the magnet, so as of the run one and run to the configuration of the trigger was, we were doing mainly the physics at the trigger level, and the selections, using the these long treks. There was no downstream text in the high level trigger, one level in the run, one and run 2
STFC-RAL-CR03 R61: now and you see, the mainly the configuration was okay, you have the value UP. Finding algorithms doing the the full long tech construction. So you have value tracks you have upstream tracks and long tag. So this was mainly the the configuration. But what we have in the run 3. Now
STFC-RAL-CR03 R61: it's quite different. We are able to do much more in in our high level, bigger one. And this is the part I want to highlight here. You still have, you know, raw data. You have the the value reconstruction. You have the ut constructions combining them. You can make
STFC-RAL-CR03 R61: forward track here. But what I want to highlight. Here is this part
STFC-RAL-CR03 R61: where you have the sci-fi ceiling, standalone sci-fi sealing, which can create the seeds out of the sci-fi. This was not envisioned in the, in the, in the run to. We can also have the downstream tracks, which are only for the for the sci-fi and the ut part. And with that you can also write the selection lines. And then that's how you basically have the events which then are forwarded to that, however, too.
STFC-RAL-CR03 R61: So one of the other things which I worked on for this is the fellow side by seating and matching.
STFC-RAL-CR03 R61: These are our simulating power
STFC-RAL-CR03 R61: trackers, which 2.7 meter long fivers, and 12 layers with 450 hits e on an average in in, in each plane.
STFC-RAL-CR03 R61: And so we, I'm not going to go to the details of this particular algorithm here. we have. What we do is mainly we have the seating at Z. First we create the seats in the XZ planes, and then we add the stereo information to confirm a seed in this in the seating conference. These, then, our mix the matched with the directly
STFC-RAL-CR03 R61: to create the forward text. This is like the forward value sci, matching part using the think approximation at the center of the magnetic field. And this was the performance. Now, this was the basic
STFC-RAL-CR03 R61: So the the side by seating was a basic element which was needed to be done in order for us to be able to downstream tracking. So that's why it was important. This is some of the performances very satisfactory performances with good efficiencies and momentum resolutions for the long treks as well.
STFC-RAL-CR03 R61: And more importantly, to be able to pull, meet the throughput requirements. This was where we have highlighted. Some of this work and details
STFC-RAL-CR03 R61: now, coming to the downstream algorithm.
STFC-RAL-CR03 R61: we have these inputs from this ipy seeds. Now, what we want to do is instead of matching them with the wallow. We want to match them with the ut.
STFC-RAL-CR03 R61: and filter out the used seeds from the sci-fi, as well as the ut, which have been already been used by the forward tracking
STFC-RAL-CR03 R61: and extrapolate these through the magnet using the think approximation. How exactly this has been implemented is that this is our track model where you have.
STFC-RAL-CR03 R61: estimation of the magnetic point initialized estimation based on the sloop of the sci-fi seed.
STFC-RAL-CR03 R61: You open a search window there
STFC-RAL-CR03 R61: for a given tolerance. Then you meet match all the possible hits in that particular search window. And for each of the possible hits which you have found. You update. Update the tolerance here and then you go to the ut
STFC-RAL-CR03 R61: open, as has been within the ut and the first layer, and then the subsequent layer, and then select the best generate. At the end you run the fake and chrome renewable. It's a very
STFC-RAL-CR03 R61: simply if I can explain. This is how it works.
STFC-RAL-CR03 R61: There are a lot of details to it, and I would, if you're interested. Please do check out the the paper and the thesis.
STFC-RAL-CR03 R61: How this has been implemented is the one of the biggest challenges to implement this was, and it took about like one year of
STFC-RAL-CR03 R61: implementation plus one year of review during the merging. So one of main challenges was to be able to read the meet the throughput requirements, and for that how it has been implemented is that we use different kind of functions within a Gpu.
STFC-RAL-CR03 R61: Each kernel has been optimized, based on the work which is doing. So we have different thread blocks for each of the of the kernels. Yeah, here you are, taking 1, 28 sci fi seeds per thread block. You are filtering out the use sci fi seeds
STFC-RAL-CR03 R61: for each. Sci C. Do you extra quality to the last layer of the ut? And then you store up to the best 10 candidates, and for each you update the slope of the candidates, using the manary point of the hit position. Give the second kernel function. Where you do 2, 56 candidates per thread block at the same time. In parallel, you add hits from the rest of the utilers, find out the best UV hits and then compute this course based on the distance between the extrapolation and the real ut positions.
STFC-RAL-CR03 R61: And then another kernel function where you find out, the best can is based on that goes from the previous function, check the duplication and perform the clone remover and the host link. And then, yeah, you, you write this output in a standard soa container for creating a multi event viewer.
STFC-RAL-CR03 R61: One of the things which we had to develop from the scratch. Was that because now we are, we are not dealing with a with a pixel detector. We are dealing with a sci-fi singular requirement and the step detector, so that we have to be able to have a way of mitigating the Clones, and both.
STFC-RAL-CR03 R61: and for that we needed to have
STFC-RAL-CR03 R61: a neural network running at the high level trigger one within the throughput, so that has to be
STFC-RAL-CR03 R61: designed from this scratch in a way that not using any of the overhead of the existing frameworks and keeping it as simple as possible. So what we have is a single hidden layer of fully connected feed forward neural network here, which was without this, our hostess were quite high more than more than like 25%. 30 so.
STFC-RAL-CR03 R61: but with that, what we have is
STFC-RAL-CR03 R61: we were utilizing the awesome tech States and the sci-fi track properties for the training, and one of the ways which we could speed up was some of the tricks which which are there in the c plus plus cuda. So using the static structure rather than using the dynamics, employing the fast math functions, and then using the unwinding for loops for doing this faster.
STFC-RAL-CR03 R61: And then this was the performance. We have good, very good physics efficiencies for these algorithms.
STFC-RAL-CR03 R61: Momentum resolution is below 6% and very moderate ghost rates.
STFC-RAL-CR03 R61: I'm sorry I'm not able to follow the time. I I follow this forward to start
STFC-RAL-CR03 R61: o'clock now.
STFC-RAL-CR03 R61: and and and so
STFC-RAL-CR03 R61: now you have. So with these algorithms, what we managed to do is you have
STFC-RAL-CR03 R61: track.
STFC-RAL-CR03 R61: which is a downstream track. You have a reconstruction on the tech which basically gives you, all the different hits which are part of this track. With that. Now you have to be able to write the selection lines. If you remember in this broad? I had seen that. Okay.
STFC-RAL-CR03 R61: one thing, one thing is the the tracking. But then you will. Then you write different physics, selection lines which can be inclusive or exclusively. You write them either, for like a tech Mba, or you write for a particular physics channel. And then what we have is now we develop. We had to write these physics lines for the Lambdas and K shorts.
STFC-RAL-CR03 R61: So for that you have to be able to do word texting.
STFC-RAL-CR03 R61: and for vortexing, because now, maybe the vertex second vertex is not in the Velow. It can be outside the Velow we again used some of the infrastructure which we had built up for the neural network and optimized it for doing the vertexing, for meeting for matching the the the best combination of the 2 tracks, and and and having imaginary vertex and then this this is
STFC-RAL-CR03 R61: this would allow us to have a good background rejection, the selection lines. And so, for example, here you have the lambda and K short in in in the simulation at that. Lt, one level and this was also this is also has been
STFC-RAL-CR03 R61: merge and part of the core software. Now the biggest challenge was to have it running in the
STFC-RAL-CR03 R61: Throughput budget which was there, and use it, as you can see, adding the downstream here. It only adds up 4 kilohertz as compared to doing everything else. So you have the matching forward and the rest of the high level table one, and if you add the downstream part, it's like only the differences about 4 kilohertz. So the algorithm has been very past, and that is the reason why
STFC-RAL-CR03 R61: it, it. It's not possible to have it in in in the production HLT. One system.
STFC-RAL-CR03 R61: one side study which we did with this work was. Also, I wanted to see how
STFC-RAL-CR03 R61: algorithms can be optimized so that they are using as little power as possible, and whether doing certain computation tasks like the way you are shorting the hits, the way you are doing different computations. Whether that will affect how much is the occupancy of the Gpu, and that affects how much is the power? So there's a there's a separate work for that, then.
STFC-RAL-CR03 R61: so, for example, yeah, you can see how the during the downstream deconstruction. How as compared to the charity without downstream, with downstream? How is the difference in the power, consumption? And so on. These kind of studies would, I mean, there are a lot of questions for
STFC-RAL-CR03 R61: have been sustainable. And so when working in the algorithm level you can try to see if
STFC-RAL-CR03 R61: there are knobs which can be tuned for having the best power usage. Now coming to the physics impact of this
STFC-RAL-CR03 R61: the channels which initially, which we see would have affected was, for example, in the B headlines you have the Lambdas cascades, for example. This has not been found yet. Why? Because 25 times it is more 25 times as compared to the long long. So this is the downtown long proportion. So if you basically see here cascade to cascade gamma here
STFC-RAL-CR03 R61: you can see this green is mainly the downstream. It is. There's basically nothing which is there in the long. So our trigger with only the long treks, would not be able to have this, and we did the searches in the Lsev using the run. 192 data. We didn't find anything. But with the casket. Now it's quite possible that we'll be able to find with this. And now this is the distribution can see a lot of these decades, for example. You have here
STFC-RAL-CR03 R61: omega v to omega pki. This is also mainly downstream channel, and then d 0 to k short pi, and then other channels as well. You see much more statistics where there were some longs, but there are like lot of which are going to be down. So with this, you you are able to do a lot of
STFC-RAL-CR03 R61: physics and the K. Shorts and lambdas with with the kings on lambdas, which we were not able to do it.
STFC-RAL-CR03 R61: So
STFC-RAL-CR03 R61: this is one of the one of the impacts which we would be seeing in the Lseb results for the we are known on physics charm physics as well as the scientists as well.
STFC-RAL-CR03 R61: Now going beyond sender model. This was the standard beyond send model. We I had shown you the how it was the efficiencies before, which was very low. But now in the same channel. If we look at this for the V 2 expanding to view new.
STFC-RAL-CR03 R61: you have
STFC-RAL-CR03 R61: the efficiencies, because now, with the downstream, what we are able to do here is
STFC-RAL-CR03 R61: we are also able to
STFC-RAL-CR03 R61: improve the efficiencies which, wherein some of these possible candidates might be leaving some places on the outside of the Velow, but still not getting detected, because how the the reconstruction works is that you traverse from the from the inner layer to the outer layer. So if you don't have any hits in the inner layer, then you basically miss it. So you have much better efficiencies in this particular channel for
STFC-RAL-CR03 R61: for going beyond
STFC-RAL-CR03 R61: 10 picoseconds. And here you can see with the downtime vertexing. You can cover these regions where you both 100 pose to 2,000 people seconds where it was basically 0 efficiency. So
STFC-RAL-CR03 R61: it's not just this particular model. We checked it with many other models. And we have this paper where you can. We have summarized some of these studies where the Elsie's potential to discover longer new physics particles with lifetime power 100 people seconds. And we were surprised to see when we compare
STFC-RAL-CR03 R61: these with some of the
STFC-RAL-CR03 R61: lifetime, friend, did experiments like Phaser pizza 2
STFC-RAL-CR03 R61: lseb. Is now able to. With the last team we are able to cover much more area as compared to without. So this is the the blue you can see. It's how much it is overlapping with. For example, the phase and Phaser 2. And this is with the 25 come to our inverse which we expect to have the run 3, and then 300 is for the run. 4.
STFC-RAL-CR03 R61: So same. So this is one dark photon. So model, we have the scalars. This is one dark scalar model where you have the sensitivity to the region which is
STFC-RAL-CR03 R61: or even going beyond the the paper. 2 sensitivities
STFC-RAL-CR03 R61: same. You can see for the heavy neutral with some of the heavy neutral laptop models which we tried. And this is with the with the action, like particles, if you see.
STFC-RAL-CR03 R61: So we have good overlap with the mandates right now. But the only difference is that we will have this data now, as compared to phase 2 which is going to have the data, and I don't know some some time
STFC-RAL-CR03 R61: in. I don't know. 5, 10 years, or something like that.
STFC-RAL-CR03 R61: Also we checked. How this, if in comparison to this, is very recent.
STFC-RAL-CR03 R61: and still being
STFC-RAL-CR03 R61: being reviewed within the paper which we have submitted for publication that.
STFC-RAL-CR03 R61: When you compare with other experiment like shape, Matsushil and Board Xp, you can see with the dance team where there was no sensitivity for the Lseb before now you're able to cover area which are overlapping with a lot of them.
STFC-RAL-CR03 R61: So this would also help in Alyssa, providing the complementary data and results in addition to these new proposed experiments.
STFC-RAL-CR03 R61: I'm now to summarize.
STFC-RAL-CR03 R61: Let's say we
STFC-RAL-CR03 R61: with the dance team is now, as at the forefront of the lifetime frontier
STFC-RAL-CR03 R61: physics now in the run management tool to pro the lifetimes of 200 picoseconds. But now in the run 3 with the new Hr. One with the downstream algorithm, it is possible to pro Bsm physics for lifetimes from 100 to 2,000 people seconds, not just the Bsm. But also huge impetus to the physics programs with the standard model Llps
STFC-RAL-CR03 R61: and this has been made possible by investing in the software and gardens. Purely. No, no, nothing, no particular changes at the detector level, or anything like that.
STFC-RAL-CR03 R61: So
STFC-RAL-CR03 R61: that's my saving. Thank you very much.
STFC-RAL-CR03 R61: You know, you're listening.
STFC-RAL-CR03 R61: Yeah, any questions of rich.
STFC-RAL-CR03 R61: I noticed that the recipes using carpx video class. So any rate, recent units actually used.
STFC-RAL-CR03 R61: So we did experiment with that. But in the production we have the A 5,000, we are not using the Rt 8 0 9 0. We did check our performance with that. And how we did have a part of code where we were trying to use the the the rate based
STFC-RAL-CR03 R61: but at the end we went with the commercial, which is the Api call
STFC-RAL-CR03 R61: for the support, and so on. With that reason is that you don't get the support from that media, and so on, and not the warranty, and so on. So yeah.
STFC-RAL-CR03 R61: any of the questions.
STFC-RAL-CR03 R61: Go ahead.
STFC-RAL-CR03 R61: when you're doing the downstream matching back to. I don't remember not developing a change detector. So there must be like, the algorithms must be specific for let's say Lambda, Dk or K. Short decay.
STFC-RAL-CR03 R61: and others that scale to a generic Lld. Details. So when you do the tracking. It's generic.
STFC-RAL-CR03 R61: You don't particularly do polymers where you just look for the hits in the detectors. Then you have the reconstruction output with that.
STFC-RAL-CR03 R61: So you have a track. You have a tech model. You are able to do the tracking and then at the selection level. Then you look for these inclusive decay channels, whether your tag is part of the lambda decay, or the K short decay, and so on. So this is also.
STFC-RAL-CR03 R61: I mean here, this particular block with the array. This is all tracking.
STFC-RAL-CR03 R61: And and then you write the selection lines based on this output of the reconstructed output. And what happens is the particle sdks in in the in between the 2 detectors, you mean up outside the ut.
STFC-RAL-CR03 R61: So yeah, I mean, in between the detectors. This comment.
STFC-RAL-CR03 R61: you mean, so between ut and Scipion, between the ut and Scipio, then, yeah, it will not be data sector with the ut. So then we have another physics program of of what? Because what happened in the in the beginning, when we did the Sci-fi scen.
STFC-RAL-CR03 R61: we did it for 2 of you to do the downstream. But then we have figured out there is actually even triggers. You can do just with this IP. The problem right now is, we don't have enough bandwidth. We are only getting alright. So if we start triggering events based on this ipad.
STFC-RAL-CR03 R61: then we will not be able to compare it at the high level, bigger one. However, we can do this in that.
STFC-RAL-CR03 R61: And so that's the difference. We do have some physics lines, dedicated physics lines which are only based on this IP
STFC-RAL-CR03 R61: at the higher ticket level, but not the one
STFC-RAL-CR03 R61: we are working on, that that we, I mean. But we have the very constrained bandwidth availability.
STFC-RAL-CR03 R61: It's it's amazing. Yeah.
STFC-RAL-CR03 R61: any other questions.
STFC-RAL-CR03 R61: Sorry? Si, silly question. But I I missed the distinction. What what is it that makes it a downstream track and not a a long track. That's I mean, you've got a very curved long track, and you've got a downstream track. What's the key difference? So the key differences? Oh, okay, that's a very important point. I'm sorry. So clear about this.
STFC-RAL-CR03 R61: So
STFC-RAL-CR03 R61: the downstream is where you don't have any anything which can be matched with the well. So this particular algorithm which creates the long term, how it does is you have 53 layers of the pixel detector. It would basically start matching hits in the offers in the pixel detector. Then you have the bellow seeds.
STFC-RAL-CR03 R61: Then you match them with the ut, and then you match them with the sci fi. So this is the long time which has covers to all the trackers
STFC-RAL-CR03 R61: in the terms of the response team we are talking about where there is no signature in the value.
STFC-RAL-CR03 R61: so only matching these sci fi seats with the ut, but making sure that it is not overlapping with any of the tracks which are there already in the with the beloved.
STFC-RAL-CR03 R61: Well, the question, and right at the beginning you mentioned. Was it a portable performance like, Explain what that is? So I don't know. In in Cms, for example, we have this alpaca.
STFC-RAL-CR03 R61: which is basically okay. You write your software in such a way code in such a way that at the end, then you can compile it with different architectures.
STFC-RAL-CR03 R61: I apologize. The library, which is like, you know, separate library. But the thing is that you have to. You expect your developers to write, using that.
STFC-RAL-CR03 R61: have those conventions which are needed for alpaca in order for alpaca to one, and then compile your code. A single board for multiple architectures.
STFC-RAL-CR03 R61: We started developing Allen
STFC-RAL-CR03 R61: mainly with the coda. That was the choice, because at that point in time there was the most mature Gpu programming platform available even today in comparison. So our whole of the
STFC-RAL-CR03 R61: of the
STFC-RAL-CR03 R61: code had been written in cuda. But then it was quite interesting. So then we found out, because.
STFC-RAL-CR03 R61: we have multiple architectures and our we don't more expect developers to write code to do multiple architectures. Also.
STFC-RAL-CR03 R61: it was before Alan was chosen as the solution for the Sm. One. So we had con parallel developments going on wherein I said T. One was also being developed for the cpus, and also for the cpus.
STFC-RAL-CR03 R61: So, and it was open review. And in the review which is basically, people expect that your software which you are writing should not be a platform dependent
STFC-RAL-CR03 R61: should not be bind to only supporting Nvidia. And so that's why we wanted to have it running on multiple architectures.
STFC-RAL-CR03 R61: What we did was, and this was one of the work with which I started.
STFC-RAL-CR03 R61: In this particular framework
STFC-RAL-CR03 R61: was we had, plus. What we did was that we converted whole of the the code base into the the hit
STFC-RAL-CR03 R61: for the Mbc. Use, and then try to
STFC-RAL-CR03 R61: see better the performance, how the performances, and so on. But then we came over with a way wherein you don't have to do that. We have these mapping libraries which basically can map the cuda calls to the equivalent tip calls or to the CPU calls. So you have the single code. But at the time of the compilation. You just provide the flag
STFC-RAL-CR03 R61: based on that particular flag. These Backend libraries map and converts it to the the code which basically based on the platform you are trying to run. This was important for Ellen also
STFC-RAL-CR03 R61: for us to support multiple platforms as well as for
STFC-RAL-CR03 R61: being able to answer the reviewers that also allowed us to have a competitive bin. Because then, okay, when we had our, we had the solution which could work on Emd Gpus or and video Gpus, as well as cpus
STFC-RAL-CR03 R61: in the
STFC-RAL-CR03 R61: sure plot with the power consumption which
STFC-RAL-CR03 R61: I was not like. Did you? Do you come to confusion with the By studying that plot. I mean, there's no financial. But we did see that. Okay, the the way, for example.
STFC-RAL-CR03 R61: you do this, the sorting
STFC-RAL-CR03 R61: we we did see that some of these math functions which we were using if we were basically doing our own calculations, it was taking a bit more time, but also bit more power as compared to these optimized math functions which are there in the library. If you use that
STFC-RAL-CR03 R61: and and many other ways. You could see the fluctuations and the differences in the power.
STFC-RAL-CR03 R61: And
STFC-RAL-CR03 R61: and
STFC-RAL-CR03 R61: and what exactly do they measure with respect to running, alerting? They're just running events on the so having the same set of Mc samples just having different versions of the code, doing things in different ways
STFC-RAL-CR03 R61: and then measuring its throughput and measuring how much power it consumed.
STFC-RAL-CR03 R61: and this in terms of this. But now this is the facility where now we have in the attendee, also a matrix.
STFC-RAL-CR03 R61: Well, with the merger request you're expected to have. Yeah, see how your organization in terms of power, and so on. How basically, that also shows you the occupancy of the card. If you I mean, you can also like with with your
STFC-RAL-CR03 R61: different Apis, you can see how is I mean, how is the memory block utilization? Or is the cool utilization occupancy of a card? But that also, you can see directly, but also in terms of power management. You can see how well is your occupy occupation of the of the
STFC-RAL-CR03 R61: yeah. So there's no conclusion. I don't know. But the thing is, it's good to have this matrix as part keeping it in mind. So that okay, future, we can, you know, see optimizations which can help in basically being us being more sustainable.
STFC-RAL-CR03 R61: I mean
STFC-RAL-CR03 R61: our last question you mentioned about using Gpus
STFC-RAL-CR03 R61: for these real time analysis. But what about could you say something about storage? What kind of storage, and
STFC-RAL-CR03 R61: how fast is it? And what was your choice for storage so at the
STFC-RAL-CR03 R61: will go through that.
STFC-RAL-CR03 R61: So here we have only the scratch storage on the Gpus which are basically the Ssds of the of the different, even builder machines.
STFC-RAL-CR03 R61: and where we store and process, and so on, and so forth.
STFC-RAL-CR03 R61: For the storage! The buffers storage, which is built a bit as a buffer. Between this there are like 2 layers of it. One is, you know, you have SSD cache.
STFC-RAL-CR03 R61: But then you also have as a baseline sata
STFC-RAL-CR03 R61: systems storage boxes. So that way makes us our like 40 TB disk storage system. So it's a combination. But I mean at the high level, bigger one, where we we have been running the algorithms and so on. It is all based on these SSD based even builder nodes.
STFC-RAL-CR03 R61: So yeah. But so the
STFC-RAL-CR03 R61: memory through port was fast enough. It wasn't your limitation. So the processing was more critical than than the input output. Yeah, we are not using like a separate storage farm, and then mapping that because then you would have to worry about each I mean the bandwidth capacity of the storage farm to your different event, servers, and so on.
STFC-RAL-CR03 R61: So here most of the processing which we are doing it is in the local Ssds and local scratch.
STFC-RAL-CR03 R61: So and basically not storing anything at that particular one. But we do store things at the local storage and there be able to take into account the soil buffers speed and so on. There.
STFC-RAL-CR03 R61: Then, I'm interested in what kind of data formats do you use to intermediate data formats? Or, yeah, we do have our MDF data form, and it's quite Lseb Pacific. I think it has.
STFC-RAL-CR03 R61: It has some evolution into what it is right now, but it means you use your kind of your libraries, your ways to encode and decode the days. Yeah, you don't using anything
STFC-RAL-CR03 R61: General. Commercial oil. And I think this was developed
STFC-RAL-CR03 R61: this award within the Cb. Mdf, I don't know. Maybe I mean they're being used by other people, or or maybe it has components which have been taken from the others for it other comments. But I would not be able to connect on that much. But
STFC-RAL-CR03 R61: the format is that has been optimized how we store it being optimized for the Lse
STFC-RAL-CR03 R61: So at this level, you don't you need to use root for anything? Yes. And you mentioned something about that. You need to to optimize the algorithm. So how you run
STFC-RAL-CR03 R61: the Gpu and you mentioned the kernel
STFC-RAL-CR03 R61: was since that's what I'm aware of, was kernel isolation involved, or what kind of kernel optimizations did you need to do? I mean, one thing, was that okay to
STFC-RAL-CR03 R61: so in this algorithm, when do I mean?
STFC-RAL-CR03 R61: One thing which you can do is that when you're writing your functions. I mean.
STFC-RAL-CR03 R61: you can have. you have to. I mean, you know you have to specify a thread block on which the functions is going to be executed in the Gpu. And one of the optimization which we had to keep in mind is that we specify because you cannot have a dynamic thread, block size, and so on. So we have to be very specific. What side of the thread block you want? You don't want to interfere with all the other algorithms in the Gpu. So then.
STFC-RAL-CR03 R61: we identified that based on the number of hits which we are going to consider in each particular block.
STFC-RAL-CR03 R61: What is the maximum third block size? We want calculated that. And then we have to optimize these, that block sizes. In the beginning we are doing the dynamics
STFC-RAL-CR03 R61: to learn to see how it is. But this obviously doesn't work. So it took a lot of time to be able to really squeeze out the throughput of the algorithm to be able to optimize it. And so that we can actually fit in the time budget.
STFC-RAL-CR03 R61: So I suppose, like, you know, 1,000 kilohertz of less as compared to what we wanted. So then, over the years we over the time we managed to have it in the in the budget. And this required optimization of different kernels
STFC-RAL-CR03 R61: based on what we are doing.
STFC-RAL-CR03 R61: Okay, we did. Thanks. Rich again.
STFC-RAL-CR03 R61: He's going to lunch over in the canteen. So if you want to join in, have a chat with lunch
STFC-RAL-CR03 R61: some.