WH11NE- Sunrise: They're on the
WH11NE- Sunrise: here on the Department of Energy Office of Science graduate Student Research fellowship program. So I've been getting funding to come to Fermilab for the past 10 months or so to help with some of the upgrades to the Spin quest. Experiment here at Fermilab. So
WH11NE- Sunrise: without further ado
WH11NE- Sunrise: I'll try to keep it. I have a lot to cover, so I'll try to go in time. But please let me know if I'm running out of time or anything. I'll start off with a brief history of the studies of the proton C. And some of the questions that led us to the sequest experiment at Fermilab. I'll then start to discuss the intellectual successor to sequest, which is spinquest, which is a fixed target trillion experiment here at Fermilab.
WH11NE- Sunrise: I'll then discuss some of my own work on the upgrade to the spinquest data acquisition system, followed by a discussion of the opportunity to perform dark sector searches with spinquest, which are helped by studies of an electromagnetic calendar we hope to install, and I'll give a brief overlook on how everything's gone.
WH11NE- Sunrise: So just kind of to talk about the history of the proton sea. So by the 19 eighties deep and elastic scattering experiments had established proton substructure. And so we know that there are 3 valence quarks in the proton, 2 ups and a down, and through deep and elastic scattering. We also learned that there's a sea of low momentum quarks and antiquarks which are continually popping in and out of existence within the proton.
WH11NE- Sunrise: And so at the time the naive assumption of this light of this light quark C in the proton was that it was flavor, symmetric, that there was no reason to think otherwise, that the number of down and up C quarks would be would be any different in the proton.
WH11NE- Sunrise: So the 1st kind of the 1st kind of evidence to come out that challenged. This naive assumption came from the new Muon collaboration or Nmc. At Cern in 1991. So this was a this was a deep and elastic scattering experiment with Muons in impacting a hydrogen and
WH11NE- Sunrise: deuterium target, and the new Muon collaboration found that this so-called Gott-fried integral was less than expected. And so this Gott-fried integral is just the integral of the proton and neutron structure functions scaled by the Burekin X and integrated over Bjorkan X. And if we naively assume that this proton lighted C
WH11NE- Sunrise: or the light quark C is flavor symmetric. Then this term would go to 0, and we'd be left with 1 3.rd However, Nmc. Found that this value was less than 1 3, rd indicating an overabundance of down type c quarks compared to up type.
WH11NE- Sunrise: And so these are the results of the Godfred sum measured over a range of of X,
WH11NE- Sunrise: and in 1996, actually the Cern Na. 51 experiment measured measured this flavor. Asymmetry at a given value of X, which is 0 point 1 8, and found again that the number of down books was greater than that of the up.
WH11NE- Sunrise: And so in 1996, an experiment here at Fermilab, E. 866, or Nusi measured this ratio, not at just 1 point, but across a range of momentum, and found not only that it supported this flavor, asymmetry at low momentum, but also, interestingly, this asymmetry had a reversal. After a momentum fraction of roughly 30%.
WH11NE- Sunrise: And so this is. This was quite a puzzle to the theorists, because there are conceivable models which could explain this overabundance. But not this sudden reversal.
WH11NE- Sunrise: So this leads us to the sequest experiment, or E. 906 at Firmite, and they had a cute little logo. This was a fixed target drillion experiment which operated on the using the firmulus 120 g. The main injector beam on the fixed target beam line.
WH11NE- Sunrise: So this was in contrast to the previous experiment which used the beam from the 800 gev. Tematron, and this had the benefit that the process which they were measuring, which is drill ion interactions. So a pork from a beam proton and anti-pork from the target proton annihilate form an offshell or virtual photon which decays into electron pairs.
WH11NE- Sunrise: This cross section. For this process they were trying to measure increases one over the center of mass energy squared. And so by decreasing the beam energy, they got actually much higher.
WH11NE- Sunrise: cross sections for this process, with the benefit of also removing some of the backgrounds that are formed like Shapeside, which scale with with S.
WH11NE- Sunrise: So
WH11NE- Sunrise: again, this sequest was studying drillion dimuons produced by interaction of proton beam with a target. So this is a complicated formula, but this is just the differential Cross section for the drill ion process in leading order, and what we can see here is that in the end it comes out to these 2 terms.
WH11NE- Sunrise: and because of the kinematics of the experiment
WH11NE- Sunrise: sequest was really searching for beam valence quarks at high momentum fraction and target c quarks or sorry beam valence quarks and then target c quarks at mid to low, momentum fraction. So really studied this term in the cross section.
WH11NE- Sunrise: So the results of this experiment. So here is the data in blue from New sea experiment to Fermilab, and then the projected sensitivity of sequest. So this is before the taken data shown in red and the uncertainties indicating the sensitivity
WH11NE- Sunrise: so sequest, took successful data and published a paper in nature which showed the results of their experiments. So this targeted higher momentum sea quarks. So going past the 30% that you see studied and measured the ratio of the cross sections for proton Deuteron interaction to that of proton-proton. To extract this flavor, asymmetry, ratio.
WH11NE- Sunrise: and so it found consistently that down type c quarks were more abundant than the up type over this range of momentum, and didn't observe the the flavor asymmetry reversal that new C saw.
WH11NE- Sunrise: So this takes us now to the next experiment in the line which is spin quest. So we're familiar with the structure of an atom, and if we zoom in on the proton. It's a composite particle with spin, one half and the initial assumption. The initial theoretical assumption was that the quarks in the proton constituted all of its spin.
WH11NE- Sunrise: This assumption was challenged by evidence at slack and then investigated at Cern, which later found that the quarks really only carrying roughly 25% of the total spin of the proton.
WH11NE- Sunrise: Further experiments of the relativistic heavy Ion Collider brought this up to around 40, or between constrained to 0 to 40% for the contribution from the gluon intrinsic spin. But then this leaves a lot of the contribution completely open. And so what spinquest is trying to understand is whether or not the c quarks and the gluons possess some sort of orbital angular momentum in the proton, and how that how and if that contributes to the total proton spin.
WH11NE- Sunrise: and I I think I'm kind of going a little slow here, so I'll just briefly go over this theory part but
WH11NE- Sunrise: the way that it. The way that spinquest is going to probe this is through things called Sivers, through transverse momentum distributions for those of you in collide physics. I'm sure you're familiar with Parton distribution functions.
WH11NE- Sunrise: Those are giving you information on the longitudinal momentum of partons. These study the transverse momentum of the Partons. Given certain polarization assumptions. So in this case, the Simrs function, which is what spinquest is trying to measure, is a transverse momentum distribution describing the correlation between the momentum of a target fork shown here in black
WH11NE- Sunrise: and the spin, or sorry sorry the quark shown in red. So it's unpolarized. Is this little dot and the spin of its parent nucleon. So if there's some difference between a spin polarized up and down with unpolarized quarks, this simmers function would be non-zero.
WH11NE- Sunrise: And so a non 0 Sievers function would be so called smoking gun evidence for
WH11NE- Sunrise: orbital angular momentum of the c quarks, which would then give us some insight into how not only the 3D structure of the proton, but how these C quarks contribute to the total proton spin.
WH11NE- Sunrise: So the goal of spin quest is to measure the so-called this single spin asymmetry. And basically this can be. It's it's much more complicated than it looks here. But this asymmetry can be extracted by looking at the ratio of the differences to the sum of the Drowion Cross section when the target is spin up versus spin down. So if this asymmetry is 0, then there's
WH11NE- Sunrise: than the
WH11NE- Sunrise: the light forks don't carry any orbital element, or the light fork. Orbital, angular momentum doesn't contribute to the proton spin. But if it's non-zero, then we have some evidence that it does. And so right here is just a plot of some theory projections. And then the spin quest sensitivity for frozen ammonium and deuterated ammonia targets. Right here
WH11NE- Sunrise: any question on the sequence results.
WH11NE- Sunrise: Is there any is blue the sequest result? So the sequest result is shown by these data points with the yellow bars indicating systematic uncertainty. These? Sorry? No. Go ahead. Okay, yeah. I was just saying, these are a different theory. So these 2 are theory predictions from something called a meson cloud model of basically virtual meson formation in the proton. But then these are, it's from the Parton distribution functions that are data driven.
WH11NE- Sunrise: These, these 2
WH11NE- Sunrise: red and blue fit to the sequence data. Yeah, fit to existing experimental data. Yeah, sequest doesn't observe this. This reversal
WH11NE- Sunrise: sequences are more or less a constant
WH11NE- Sunrise: 50% based on that. I guess maybe we'll talk about this. But it's been Quest trying to like disentangle them, which
WH11NE- Sunrise: not necessarily Spoonquest is really just trying to up trying to understand the the orbital, angular momentum of the the light ports in the scene.
WH11NE- Sunrise: So I'll note that this there are theoretical models which establish this difference.
WH11NE- Sunrise: Okay, so this brings us, then, to the spin quest experiment here at formula. So the spinquest is, as I said, a fixed target proton beam dump experiment. So it's using protons from the 120 g. The main injector, which are diverted to the switchyard and then down the beam line to the spin quest experiment Hall. I guess you can't see it from here. But if you go to the crossover you can actually see Nm. 4, which is where spinquest is located from the 11th floor here.
WH11NE- Sunrise: So here's kind of just to give you a little lay of the land, familiar main ejector behind us, and then the tetratron. To this direction the beam is diverted through the switchyard to Nm. 4, which is just down one of the fixed target beam lines. And here's kind of a vision of what the actual experiment looks like from above in the experiment hall.
WH11NE- Sunrise: And so this is looking upstream. The the protons from the manufacture are coming at us, and they are going to hit the target somewhere over here and then pass through the spectrometer, and I'll now give you some. I'll give you a rundown of what the spectrometer actually consists of.
WH11NE- Sunrise: and how it performs the measurement.
WH11NE- Sunrise: So this is the spectrometer. It's measuring the spectrum of dimuons that are produced by interaction of the high intensity, 120 gev. Beam with a polarized ammonia and deuterated ammonia target. This is actually a really interesting subject, but I'm not really qualified to talk about it. So I've linked to some very good talks if you are interested to learn more about this polarized target. But the
WH11NE- Sunrise: The idea here is that after after interacting with the target, the resulting particles from the collision pass through a roughly 5 meter solid iron magnet, which which acts to sweep away acts as a beam dump, so it'll sweep away soft standard model radiation.
WH11NE- Sunrise: and then the dime ones that are produced that are being studied will pass through 4 sets of tracking stations, consisting of hodoscope arrays and drift chambers which can measure the
WH11NE- Sunrise: the passage of these neurons through the spectrometer. So we can obtain measurements of their momentum and their kinematic distributions.
WH11NE- Sunrise: so that this is done with the main injector beam, and when the experiment is running, the beam spills onto the target for a duration of roughly 4 seconds every minute. And these are it's a very high intensity beam. There's roughly 5 times 10 to the 12 protons per spill, corresponding to around 28,000 protons per Rf. Bucket, which is being driven by a 53 Megahertz Rf. Block.
WH11NE- Sunrise: and so the original design goal for spinquest included 2 years of running on both targets and the integrated protons on target for that duration was 1.4 times 10 to the 18. So it's very high luminosity experiment, very high intensity.
WH11NE- Sunrise: So I'll go through some of the component. The spectrometer components that I mentioned briefly. So. The 1st are the these hodoscopes. So these are plastic scintillator hodoscopes that are located at each of the tracking stations, and these are, you can see the schematics of them. The actual scintillator paddles are connected to photo multiplier tubes which read out the signals.
WH11NE- Sunrise: and so these offer a slightly lower resolution. But a quick response. And so these are used for signals that make it into the experiments fast. Fpga trigger
WH11NE- Sunrise: the next component to the spectrometer. That's of interest to us is the drift chambers. And so this is kind of a structure of them looking on to
WH11NE- Sunrise: looking at them head on. So these act to provide precise measurements of the Damuon's position at each of the stations, and then also because of their position, resolution of 400 microns. This gives them, or this gives sequest at least a momentum resolution of 3%.
WH11NE- Sunrise: So the final component that I'll talk about are these proportional tubes. So if you remember from the diagram, you probably don't. They're located at the end of the very end of the spectrometer, and these are used for muon identification. So these are 12 foot long gas cubes. That measure ionizing radiation as charged particles pass through, and they give in the final. They give in the end precise measurements of the muon positions in
WH11NE- Sunrise: in the, in the bend plane, which is, if we're looking down on the experiment, and we want to bend this plane.
WH11NE- Sunrise: and then also, they're expected to form a straight line in the vertical plane.
WH11NE- Sunrise: So hits from these proportional tubes are then used to form tracks which we then use to, you know, reconstruct the vets in the experiment.
WH11NE- Sunrise: So here's kind of a little timeline of of spin quest as it's been
WH11NE- Sunrise: from its inception to currently so for 2013 to 2017 sequest took its data. During that time the spinquest collaboration was formed and performed studies of polarized target?
WH11NE- Sunrise: and and then this brings us to 2018, at which point
WH11NE- Sunrise: approval for a 2 year run of this newquest experiment with polarized neutrons or protons and Deuterons was was granted.
WH11NE- Sunrise: Sequence was started being decommissioned in 2019, and then the Spin Quest Commission began using a cosmic runs.
WH11NE- Sunrise: this. So there were a couple of other. So in 2022 it was fully constructed, and commissioning of the cryogenic system for the detector. Again, and
WH11NE- Sunrise: in
WH11NE- Sunrise: in 2023 there was actually conditional approval granted for the spinquest upgrade which corresponds to studies of enabling dark sector physics at spinquest and also optimizations of the spin physics program
WH11NE- Sunrise: so last May spinquest actually received its 1st beam and took 6 weeks of commissioning data. So I don't know if you're around. Last summer, when data was being taken or we had the beam. But it was this data was it kind of it would suffered from very hot temperatures which reduced the
WH11NE- Sunrise: the actual time that the main injector could be could be running. So it received some initial commissioning data. But then, in November last winter, the main injector, there was a transformer fire at the main injector, which unfortunately, has taken out the capability to use the main injector, for now you know.
WH11NE- Sunrise: quite some time. And so this isn't forecast to be fixed, I think, until 2026. I don't recall the actual timeline now. But unfortunately, that's that's the situation.
WH11NE- Sunrise: that itself in now the Commission data was with a dummy target. Yes, and with what, what? How many protons per spill
WH11NE- Sunrise: I don't know. Off the top of my head. I have some.
WH11NE- Sunrise: I think I have a plot in the back of commissioning taken or data taken from commission. I mean, we. We tested it with different scenarios, and brought it into the power of the elements to take with the, with the solenoid energized.
WH11NE- Sunrise: yes, and and with the. And we run like essentially into integration with together around like 10 to 15 of the perform target with the portal, with the target portal wise.
WH11NE- Sunrise: So I mean, we can we instruct some like the some events? Yeah, we we actually track some events. But
WH11NE- Sunrise: but I think so. This the statistic is still low to get, you know. My my concern was just that the the back end stay super conducting
WH11NE- Sunrise: it went from. There was no issue of beam spray.
WH11NE- Sunrise: That's why I was. Yeah, we-, we see some issues. And I think this, the target group are actually trying to. There are some-, some- sometimes it's the
WH11NE- Sunrise: they- they call this I forget the name. But yeah, sometimes they- they see some like the very high intensity of the spiel. They always just a break magnet, but it's not always happens, and we are trying to trying to see what, whether we can save that team next.
WH11NE- Sunrise: yeah. So this is also whether this is usually the student on spend quest things issue pieces on the experiment.
WH11NE- Sunrise: So, yeah, thank you. So in the meantime, as the transformer
WH11NE- Sunrise: it's been our commission and main injector. This is giving us some time to work on a proposed upgrade to spinquest data acquisition system. So I'll give give an overview of the spinquest data acquisition using some slides from Noah Palladino as a graduate student at Mit, who's an expert on the spin quest stack and has worked with it extensively. So we're working together to perform this upgrade. So
WH11NE- Sunrise: this is the the general. This is the spectrometer. Here you got beam dump, and then the 4 tracking stations, all of whose data detector data gets fed to the trigger and then to the main data acquisition system to report information.
WH11NE- Sunrise: so just briefly, there's 3 kind of components to the the data acquisition system. The 1st is this beam deck. And so there's a Cherenkov gas detector which measures the beam intensity on a per Rf bucket basis.
WH11NE- Sunrise: And it does this because the intensity is not linear throughout the spill. And so you can have sometimes buckets with more protons, and then some with fewer. And so, if you have very high intensity buckets. This will saturate the detector, and so this acts to inhibit triggers around in a window. Around these high intensity Rf buckets.
WH11NE- Sunrise: There's also the Scalar Dac, which tracks the number of counts per still for all of the different experimental triggers, and then also perform some offline data quality and monitoring functionality. And then the topic that I'll discuss in the next couple of slides is the main deck, which is the focus of our upgrade to the hardware and the Fpga firmware which which are running in this this main deck.
WH11NE- Sunrise: So here's a kind of high, level overview of the spin post Main Dac system?
WH11NE- Sunrise: So it's comprised of 16 readout grades, I believe. Which which house? These tdc modules, these Tdc modules just perform digitization of the data coming off of the spectrometer from each of the different detector components. And so I think in total, there are 89 boards in the 16
WH11NE- Sunrise: between these, between these groups.
WH11NE- Sunrise: so the kind of high, level overview of how it works that once the experiment fires its trigger, the trigger that it's sent to sent to this, so called Trigger Supervisor.
WH11NE- Sunrise: which which then issues a common stop to all of these Tdc boards which are recording the data. There's then a 30 microsecond long dead time, while the Tdc's record their data to buffers that can be then sent over the readout rates backplane.
WH11NE- Sunrise: there's some interface between. There's some interaction between trigger interface and here and and then the the readout great CPU, which
WH11NE- Sunrise: which then informs the the readout crate that the data is finished being read out and tells the Trigger Supervisor that that all the readout crates, or that the readout crate is finished reading out the data once all the crates are finished, then the trigger trigger Supervisor is then available for for future triggers. So unfortunately, there's this dead time where a new triggers can't be accepted. Corresponding to the readout times of these detector components.
WH11NE- Sunrise: So just zooming in on this a little bit, these Tdcs are time to digital converters. So these are custom electronics developed for spinquest by a group and by the by, the collaboration. And they have this, they're they use the Vme bus form factor. So they're they're intended to slot into these Vme crates, and so they can communicate over the Vme backline
WH11NE- Sunrise: and so the readout crate looks like this, and all the Tvc slot in there.
WH11NE- Sunrise: and so this these time to digital converters, what they do is they digitize the arrival time of the signals from all the detector front ends front end electronics. With respect to the trigger time.
WH11NE- Sunrise: And so what they can do is they measure the difference between the arrival of the trigger and the arrival of the hit from the different detector components, and this information can be used to understand the drift time which can be related to the drift distance, and then is used for event tracker construction.
WH11NE- Sunrise: So each of these ports has 64 channels from the different detector front ends. And the firmware on them features. Multiple hit illumination logic which can remove very short pulses in quick succession. And they have a timing resolution of point 4 5 Navicent, so like it.
WH11NE- Sunrise: And then there the-the-
WH11NE- Sunrise: the general principle of how these work is that from the let's just take the drift chambers as an example. Charged particles interact with the wire chambers, ionizing the gas and causing a notable signal
WH11NE- Sunrise: this electrical signal is is read out by custom electronics which are directly connected to the detector front ends and the so-called Asdq boards. These are amplification, shaping, discrimination, charge integration boards, so they shape the pulses and discriminate them to pass them along to the tdc boards which then digitize the arrival times of these hits and the triggers with respect to the main injector Rf. Clock.
WH11NE- Sunrise: and so
WH11NE- Sunrise: these boards, upon receiving triggers, will write their data to buffers, and then, after the spill ends, the Tdcs can can write their data out after the spill ends. And so here's kind of a little distribution, for instance, of the measured times from the different detector components. So that's what that would look like.
WH11NE- Sunrise: So this not to not to belittle the success of these Tdcs because they're quite impressive
WH11NE- Sunrise: pieces of hardware and firmware, but they they do introduce some slight bottlenecks into the the data acquisition system.
WH11NE- Sunrise: namely, that the actual amount of buffer space that's located on the Tdc board is pretty low. And so this limits the amount of data that they can store and then lowers the trigger rates of the experiment.
WH11NE- Sunrise: Also they exhibit, or they induce this large end time during the spill wherein, after the trigger has arrived. There's this 30 microsecond delay, as the Tdcs are reading out their data, and during that time the Trigger Supervisor is busy and can't accept new triggers. So a proposed solution to some of these problems are to replace these Tdc Tdcs on the Vme carrier cards with a system on module solution.
WH11NE- Sunrise: And so we've been targeting a couple of different solutions. But the one that has the most progress so far is utilizes these Amd Korea, K. 26 system on modules. And so these feature these feature zinc ultra scale plus system on ship
WH11NE- Sunrise: with a very powerful Fpga. Lots of on chip, lots of onboard memory and access to peripherals, and the great thing about these system on modules is that they can be fitted to custom carrier cards which can then perform. You know, application specific tasks.
WH11NE- Sunrise: So, for instance, here the system on module, and I'll say, this is this is the blank, or rather an unfilled Pcv. That Noah has designed at Mit, which will house the K. 26 on so it would fit right onto here, and then Lvds connections to the different detector front ends
WH11NE- Sunrise: would feed data into these Tdc, and it would also have access to peripherals like Ethernet.
WH11NE- Sunrise: So the
WH11NE- Sunrise: the upgrade to the firmware kind of. I'll just give an overview of how how we've started to look at upgrading the firmware to kind of reduce these bottlenecks. So this is a a high level overview of the firmware. But basically the way that this works is that we would like this to be a 1 to one replacement for the existing Tdc boards. And so they will take in 64 inputs from different detector front ends. And what they'll do is they'll work.
WH11NE- Sunrise: each of these 64 inputs corresponds to a single Tdc channel.
WH11NE- Sunrise: which consists of a sampler module and an encoder module, and these measure the arrival time of the front end discriminator inputs with respect to an Rf block, so that timing analysis can be performed.
WH11NE- Sunrise: So the way that the top level works is that the data from all 64 channels are written to one of N ring buffers in this little illustration. It's just 2 ring buffers.
WH11NE- Sunrise: But the idea is that the the firmware can write the data to one of the buffers, and upon the arrival of a trigger can switch its right pointer to the next ring buffer, while software on the system, on module, on running on the processor can read out the old ring buffer, and with a system like this?
WH11NE- Sunrise: you actually can achieve 0 0 dead time because you can. The Tdc doesn't have to stop taking data that can continually take data, as its old data is being run being read out.
WH11NE- Sunrise: And so we we can also just bypass the need for Vme cards for this old Vme crates entirely.
WH11NE- Sunrise: And so I just also included a little little diagram down here. So basically, the so far
WH11NE- Sunrise: in our design, we have, you know a 64 bit word from the Tdc, so there's 6 bits corresponding to the channel. Id. 0, through 63. There are 5 bits encoding this this fine time, which I'll discuss in the next slide, and then there are 28 bits encoding a course time
WH11NE- Sunrise: which I'll again discuss in the next slide
WH11NE- Sunrise: The way that this this multi, this, this fit sampling is achieved is through a process called multiphase sampling.
WH11NE- Sunrise: So basically, we have a phase locked loop that's running in the Fpga, which takes in the main injector Rf. Block running at 53.1 Megahertz and outputs a clock at 4 times that speed at 212.4.
WH11NE- Sunrise: This phase lock loop produces 4 output clocks, each shifted from one another by 45 degrees, and the reason for doing this is that if you sample the rising edges and the falling edges of all of these clocks over an entire Rf. Period, which stretches roughly 20 nanoseconds at a main injector frequency of 53 Megahertz.
WH11NE- Sunrise: Then you can subdivide the entire Rf. Period into 32 bins, whose width is roughly point 5 8 nanoseconds
WH11NE- Sunrise: and so you can then digitize the arrival time of the hit within this Rf. Period
WH11NE- Sunrise: to a precision of 0 point 5 8 nanoseconds, and, as I mentioned earlier, there's a there's this course time associated with each of the data, and we have a free running counter in the Fpga running, which is which is incremented by the Rf. Block.
WH11NE- Sunrise: and at 28 bits. This gives us roughly 5 seconds of dynamic range to attach each of the hits or which to encode a course time for each of the hits. And so basically, this covers the entire long, entire 4 second long main injector spill, so you can place the arrival time of the hits and the triggers within that spill.
WH11NE- Sunrise: Alright. This might be a little bit technical, but I think it was pretty interesting to show the capabilities of what you can do. But basically, the multiphase sampling method relies
WH11NE- Sunrise: kind of on very precise placement of the sampling flip-flops within the programmable logic fabric of the Fpga. And so we've developed this method not developed. But we utilize this method for automatically placing the sampling registers such that the input hit signal. Let's say this red line reaches all of the sampling flip-flops that's shown over here as close to the same time as possible, and so this reduces the need for inter channel calibration, and gives us
WH11NE- Sunrise: an accurate measurement of the arrival time of these hits, since the signal should be arriving to all of our samplers at the same time.
WH11NE- Sunrise: So some initial tests of the
WH11NE- Sunrise: some initial tests of this. They're just gonna try to go a little fast because there's still some stuff to cover. Some initial tests of this firmware indicate what we did is we emulated detector hits and sent them to our Tdc. Firmware space, 500 nanoseconds apart
WH11NE- Sunrise: we. Then the firmware then digitize the arrival time of these hits wrote them to shared memory, and then we'll read out by the processor running on the Soc. And so we've found that the that this Tdc. Firmware can recover this time difference. So at 500 nanoseconds that corresponds to point 5 microseconds apart, and we can see that each of the 4 channels reports their hits point 5 microseconds apart.
WH11NE- Sunrise: We can also investigate so this is shown for 4 channels. But again, the design is implemented for 64, but it's easier to see for 4
WH11NE- Sunrise: we also checked, took a look at the difference in this this this course arrival time between each of the adjacent pits and found found these distributions to be within within expectations. So these slight deviations were were attributed to the pulse generator that we use for the test. So not exactly sending the pulses 500, exactly 500 nanoseconds apart.
WH11NE- Sunrise: But basically what this is showing here is that in this experiment we had one Rf. Clock period. So the slow clock which is driving the logic or driving the phase lock loop, was running at 50, Megahertz giving a 20 nanosecond period, and so this mean of the distribution at 25 rf. Periods corresponds exactly to 500 nanoseconds, which is the period at which the pulses were sent to the firmware.
WH11NE- Sunrise: So this is the actual the custom hardware that's being designed at a test stand at Mit. So here's the here's the K. 26 sum on this Development Board from Amd. And Noah at Mit is developing these signal generators based on the raspberry pico which can be used to generate extremely fine timing, or which can be used to measure the the timing resolution of our tdc,
WH11NE- Sunrise: It's a very, very high precision, and also measure inter channel calibrations.
WH11NE- Sunrise: So some. The outlook for this is that we will continue to work on the firmware and then test it at the test and at Mit and so this will involve testing the data rate. So basically blasting all 64 channels with signals from the the pico at at very high frequencies, and then gradually decreasing the rate to measure what our maximum data rate can be.
WH11NE- Sunrise: performing timing alignment per channel calibration. So basically, we can measure the delay per channel and correct for that, and then eventually integrating this at Fermi Lab or at spinquest. Once it starts to run again. So the idea is that we could test it parasitically during cosmic runs. When spinquest starts up again and we can measure the performance and the the behavior between our new Tdcs and the ones that are currently at spinquest.
WH11NE- Sunrise: So with that in mind, I'm going to segue into a discussion on how spinquest can be used to probe dark sectors, which is kind of the next part of the upgrade to spin quest.
WH11NE- Sunrise: So
WH11NE- Sunrise: we have plenty of evidence that dark matter exists and is out there, but the searches for it, especially for weekly interacting massive particles, have been largely, entirely unsuccessful in the Gev to Gev.
WH11NE- Sunrise: So an alternative formulation is that dark matter, instead of it, may, instead of existing in isolation, could exist as part of a larger dark sector which are basically hidden quantum fields that interact indirectly with standard model fields through extremely weak portal interactions. So we have our standard model that we know. And this dark sector, which could be comprised of
WH11NE- Sunrise: dark quarks, Higgs, Leptons, etc, and interactions between the 2 would be mediated by mediator particles whose spin and parity determine the nature of the interaction. So, for instance, a vector interaction could involve the sound model photon and the dark photon.
WH11NE- Sunrise: But these these models arise in many different Bsm theories that try to explain things like the hierarchy problem or the strong Cp problem, invoking axions, etc. But for experimentally for experimentalists. The kind of the you know. The
WH11NE- Sunrise: the upside to all of this is that, despite the model they predict the case which is visible standard model particles which provide us with a viable experimental target. To look for and spinquest actually is. One of the is A is a great place to look for these because of its nature as a fixed target proton beam dump experiment. So the
WH11NE- Sunrise: So I'll now introduce darkquest, which is kind of the colloquial name for the upgrade to spin quest which enables searches for dark sectors, dark sector particles.
WH11NE- Sunrise: And so the kind of novelty of this is that it can use the existing detector infrastructure from spinquest to enable searches for these dark sector signatures. So I'll just give you an example with the dark photon. But essentially what happens.
WH11NE- Sunrise: The idea here is that you know. We have the high intensity, 1 point G proton beam, and it could produce these very weakly interacting particles and depending on parameters of the theory. They could have lifetimes long enough to produce to be produced at the target and decay within the beam.
WH11NE- Sunrise: And then, through some sort of mixing with the standard model photon would produce. You know.
WH11NE- Sunrise: visible decay products that we can observe. For instance, let's say I mentioned that new ones, because finquest actually already has some hodoscopes installed to look for displaced signatures.
WH11NE- Sunrise: but the idea is that currently spinquest can only look for displaced dine uons, however, darkquest proposes installing an electromagnetic calorimeter somewhere downstream in the experiment, and including this calorimeter, would enable darkquest to search for different final states, like electrons, photons, ions, etc. And these are all final state signatures of a wide variety of dark sector physics, models.
WH11NE- Sunrise: So what makes spinquest such a good
WH11NE- Sunrise: such a good candidate for these searches is actually, is this nature as a fixed target beam, dump experiment? So by by nature of the fact that we have this large focusing magnet, this 5 meter long focusing magnet in front spin.
WH11NE- Sunrise: At least, you know, these these dark photon searches, for instance, would have low standard model backgrounds, but very good opportunity for signal identification. The the 5 meter, long ironf Mag would would remove the soft standard model radiation ahead of the spectrometer, and then the momentum measuring K magnet could separate these lightly, even very light boosted, charged particles.
WH11NE- Sunrise: And so this makes inclusion of an electromagnetic calorimeter, for instance, quite an appealing idea, because it would be very rare for dielectrons to be hitting
WH11NE- Sunrise: to be produced. There are some processes which could which could create it, but it would be rare to have a dielectron signature in an em. Cal located that far down the spectrometer.
WH11NE- Sunrise: So again, spinquest would offer high luminosity, or a large luminosity over its lifetime, but very high intensity, and Em Cal rely on us to search for new final states
WH11NE- Sunrise: so this is just a theoretical benchmark. After 2 years of running spinquest at the 1 20 Gv. Beam energy. And in this model. The coupling between the photon and the dark photon is very low, 10 to the minus 6. And so we can see even for this very low coupling millions of
WH11NE- Sunrise: of of- of
WH11NE- Sunrise: dark sector candidates could be produced through various methods most most prominently proton Bremistral, but also through neutral meson decays like the pyon, the Eta omega, etc.
WH11NE- Sunrise: drill down like production could occur but for higher masses. And it's it's suppressed.
WH11NE- Sunrise: So to enable these dark sector searches.
WH11NE- Sunrise: The idea is to include this electromagnetic calorimeter. And again, this, I think this is really neat, that the proposal suggests reusing the electromagnetic calorimeter from the Phoenix experiment at Brookhaven National Laboratory.
WH11NE- Sunrise: So this is a heavy ion Collider. There's a heavy Ion Collider and Phoenix is a detector studying those collisions, and it ran from 2,000 to 2016, where the calorimeter was used extensively for particle identification.
WH11NE- Sunrise: The calendar itself is a sampling calendar. So it has interlaced lead and scintillator
WH11NE- Sunrise: tiles. In each of these each of these towers. So to to measure the the energy of incident particles.
WH11NE- Sunrise: they're 18 radiation lengths in depth to capture the full electromagnetic shower. And they're structured in these 4 tower modules. Basically, you have the Lennon scintillator towers and then wavelength shifting fibers bring the light that's generated out to these fiber bundles in the old experiment. And here's where it would. Look. Here's where it would be situated in a ring around the detector
WH11NE- Sunrise: at Phoenix. So at Phoenix. They use photo multipliers to read out the light, but they require very high voltage, and they're pretty old. So
WH11NE- Sunrise: The goal of the Em Cal testing is to look for
WH11NE- Sunrise: is to is was to investigate. The use of silicon photo multipliers to replace these old photo multiplier tubes. And so specifically, they're using multi pixel photon counters from Abumatsu and
WH11NE- Sunrise: these these were. These are the Pcbs of the systems connected to some with some connector on the back side right here from which to read out the signal and send it off to
WH11NE- Sunrise: back end electronics.
WH11NE- Sunrise: And so these systems get placed up against the fiber bundles to measure the light. And then the entire 16 channel Em. Cal Test module is is situated in this dark box.
WH11NE- Sunrise: So the 1st tests of this Cal were performed at Boston University by no other than our own Christopher Cosby and other students at Boston University. And so this. These tests were performed with cosack Mu ones running straight through initially straight through the detector.
WH11NE- Sunrise: and these initial tests indicated from the very high different incidence of high energy neurons indicated that some form of attenuation was was required in order to stop the readout from getting saturated. Both of the sipm and the electronic ports.
WH11NE- Sunrise: and so tests were also performed of the sip of response using leds.
WH11NE- Sunrise: But this was all in preparation for a run at the Fermilab test beam facility last summer. And so the way that. So this is a photo of the back of the Em Cal Test module. You can see all 14 channels, and you can see the fiber bundles coming off of the E-cal powers. And so, as you said, these tests, these initial tests indicated. Some form of attenuation was needed to
WH11NE- Sunrise: to to attenuate the signal and stop the readouts from getting saturated, so 2 different forms were were tested. One was a neutral density filter for optical attenuation.
WH11NE- Sunrise: But so you can see here. This is the filter placed over the fiber bundle with some spacing as a blank spacing. PCB. That would then attenuate the light coming to the system.
WH11NE- Sunrise: Electrical attenuation was also tested.
WH11NE- Sunrise: And so here's a picture of the of the E-cal in the formula test beam facility. So this is looking at it from the side where the test beam is incoming from somewhere over here and striking the the e-cal. The cal itself was placed on a motion table.
WH11NE- Sunrise: which allowed us to move. The cal in the transfers in the plane transfers to the beam, and by doing so, and by using the test beams new on beam mode we could, we could direct
WH11NE- Sunrise: so
WH11NE- Sunrise: we could test. We could direct the beam onto each of the channels independently and measure their response, calibrate each channel, and so, coming off of the readout by the readouts, are sorry the siphoms were read out to or the zip. The signals from the siphons were sent to these commercial cane readouts for analysis, and the the cables themselves were had an sma splice in it, so the different electrical attenuators could be
WH11NE- Sunrise: could be added in series.
WH11NE- Sunrise: So this is just a little photo of all of us from last summer. It was a really great time. It was
WH11NE- Sunrise: like, I said, it was extremely hot, and so during the day, most of the time the main injector. It just it was overheating, and so it. Kinda the performance was degraded during the day, but we all learned a lot, had a great time and took shifts taking data with the Cal
WH11NE- Sunrise: And so this is our. So our little group here that went to, or part of our group that went to the testing facility last summer, and this is also from a different point of view. So now this is where the beam would be would be coming through to strike the e-cal over here. And then the control center was right over there, past the little interlock.
WH11NE- Sunrise: So, having calibrated all the channels, the e-cal energy
WH11NE- Sunrise: could be summed up and measured at different beam energies and with different forms of of attenuation, and this was done by using the low energy pion runs ranging from 2 to 30 gev. We could. We could. We could measure the Mcel's
WH11NE- Sunrise: energy resolution as a function of the beam energy, and it was found from these results that the resolution is on par with, in some cases better than other similar calorimeters that are being studied in a range above 10 gev. And so this is really promising, because preliminary studies of the expected signal events show that roughly, 90% of them should meet that energy criteria.
WH11NE- Sunrise: So this is quite, a very good resolution.
WH11NE- Sunrise: So just kind of summarize the findings from the Em. Cal. As I showed good resolution in the range of the characteristic signal energies was observed by the Emcal. Here's a plot of the E-cal's energy response that shows very good linearity across a range of beam energies.
WH11NE- Sunrise: And importantly, these tests establish that the whole readout system functions as expected and can be used. So this is a very promising sign for the inclusion of the Em Cal in spinquest to enable dark sector searches.
WH11NE- Sunrise: and it was hoped that we could take some some parasitic data while Spin Quest was running. But unfortunately, due to the situation. It's it's it's sitting there right now in that M. 4 just waiting
WH11NE- Sunrise: the beams group. Zoom, and it's situated right behind the station. 3D.
WH11NE- Sunrise: So in summary, I would just like, I hope, that. And kind of you know. Maybe if you're if you're on Cms. You might not have heard of Spin quest before, but I hope that now you have some idea of the physics that it's capable of.
WH11NE- Sunrise: and it really does offer a world leading spin physics program which improves the dynamics of the light sea quarks in the proton gives some insight into the structure of protons, and hopefully shed some light on this puzzle as to where the spin of the proton is coming from.
WH11NE- Sunrise: Stink was also been shown that it can be used to probe a wide range of dark sector models at relatively low cost. Again, it's using existing detector infrastructure and components recycled from other detectors, and it can do this all on a very short time scale, barring main injector
WH11NE- Sunrise: catastrophes.
WH11NE- Sunrise: and it can probe some very interesting kinematic regimes. We tested the Phoenix em cal, and found that it should be suitable for the dark sector program, and currently coordinating with spinquest to investigate its integration into the experiment. And we're also looking at upgrades to the data acquisition system which are currently being.
WH11NE- Sunrise: which we which we hope will improve the trigger rate and the reliability of of the the data acquisition system.
WH11NE- Sunrise: So with that, I'd like to to thank everyone. Especially Lpc, you know, I've been working here on spinquest, but you know, my thesis really is also about the Cms. And so I've learned so much from everyone at the Lpc. And so many great events and talks and really learned so much.
WH11NE- Sunrise: You know a lot of friends here, and it's been really wonderful energy, of course, for for sponsoring me to come here and work for my lab, and you know my mentor is not here, but as he's traveling right now.
WH11NE- Sunrise: really, you know, provided me with so many opportunities. And of course, the Spin Quest collaboration. I've linked to it here. But it's a really wonderful collaboration, and they've done some really impressive work on the target. I I wish I could cover it. But just in general very well established collaboration that will produce really really impressive physics results.
WH11NE- Sunrise: There's, of course, the darkest collaboration as well. So this is at our 1st meeting 2 years ago. And so this is a, you know, a collaboration with experimentalists and theorists across a wide range of universities and national laboratories.
WH11NE- Sunrise: and
WH11NE- Sunrise: yeah, just I guess I'll leave it off this little mementos of Fermilab and and Chicago. I mean, I didn't go to Chicago as often as I like, but it's a beautiful city, thanks to Jan and Fermilab engineers. I spent a lot of time learning about accelerator physics here. And I thought that the main control room is just really really cool to see. Lpc, of course. And
WH11NE- Sunrise: yeah, it's my my bike got me through a whole year here. Coldest winter I've ever experienced. But yeah, so not even not even. But yeah. So thank you all. And
WH11NE- Sunrise: oh.
WH11NE- Sunrise: any questions?
WH11NE- Sunrise: I have a few, but somebody has more. What's what's the what's the dead time at add that was observed at one e. 12 per spill in the in the test.
WH11NE- Sunrise: I'm not sure it's a function of the
WH11NE- Sunrise: Noah, I think, is Noah's connected Noah. Do you happen to know from the commissioning data.
Noah Paladino: Off the top of my head. No, but I think it was around 28 microseconds.
WH11NE- Sunrise: You know, like the frac, you know the fractional dead time. So you know not not- not the the time, and you know that the time that it's disabled. But
WH11NE- Sunrise: it right? That's a function of the number of interactions.
WH11NE- Sunrise: right? Per set, you know, per unit time. So and that 28. So what what if you're at? An intensity of
WH11NE- Sunrise: of only 12 per spill? Right then? What is what is the dead time fraction?
WH11NE- Sunrise: I'm not sure. Off the top of my head. Okay,
WH11NE- Sunrise: what's this out? So for the new electronics, what's the ring size?
WH11NE- Sunrise: The ring size, the depth? Yeah. How many, how many buffers in the ring? Oh, the new electronics. Currently, it's it's user, configurable. I've been testing with with 2. But I've gone up to 5. Okay, yeah, alright.
WH11NE- Sunrise: And and so this, of course, would lead to, you know, potentially higher trigger rates, because you could buffer these triggers and have more readouts to to read from. Yeah.
WH11NE- Sunrise: So
WH11NE- Sunrise: the main injector right, the main injector ramps from from 8 Gb to to 120. So the if you're if you're actually looking at the main injector clock, right beam sent clock that that actually that frequency then changes over the course of the ramp.
WH11NE- Sunrise: So how long does it take that Pll to lock at the at the 53.1 Megahertz? That's a good question. I actually haven't tested it on the Rf. Clock. I've been using an emulated clock, is there? Well, is there a reason that you need to run off the Rf. Clock?
WH11NE- Sunrise: So it just makes it simpler to calculate the I mean because we're we're trying to digitize these hits with with respect to the Rf. Clock itself. And so if we use the Rf clock as input to the phase lock loop, then our output clocks are synchronized to that phase, and we can measure the the time with respect to the start of an Rf period.
WH11NE- Sunrise: So, okay, cause yeah, I mean, it does. You know you, you do have the ramp. So I don't know if it's possible for
WH11NE- Sunrise: 80 to, you know.
WH11NE- Sunrise: Give, you know, generate that with everything that's down, but that you know that. There's not a lot of time between
WH11NE- Sunrise: right when when you get to Flat Top and and the spill starts
WH11NE- Sunrise: so that that yeah, and that's that's a very good point. We will have to investigate that with the actual Rf block when we when we have access. Yeah, again, you could, you could talk to Ad and see if there's some way you can test that.
WH11NE- Sunrise: Okay, yeah. Where is the right now? Is it still in, or has it been rescue parts of it?
WH11NE- Sunrise: So I think it's still at Berkhaven. Maybe no or Phil can can correct me if I'm wrong.
Noah Paladino: The majority is still at Rookhaven. Yes.
WH11NE- Sunrise: Okay, is there a plan for the integration?
WH11NE- Sunrise: Yeah, next year and a half on that bike? You're gonna just
WH11NE- Sunrise: yeah. I I believe the plan is, I mean, there still has to be discussion with the collaboration as to where and how I think geometries might have to be changed or switch on the geometries. We're still investigating how
WH11NE- Sunrise: how that would affect the regular spin bus tracking performance and whether it would affect the spin physics goal.
WH11NE- Sunrise: But
WH11NE- Sunrise: I'm not too sure off the top of my head when we'll begin to integrate, like the large M. Cal sectors in in the experiment, or if that will happen with the next next run. Whenever the main injectors back online
WH11NE- Sunrise: interfere with the spin business, just in the sense that if you have to move the tracking stations around the tracking algorithms. So collaboration just wants to be sure that any addition of this thing would negatively impact the
WH11NE- Sunrise: slide. 43.
WH11NE- Sunrise: Yeah. So I don't think that picture is quite right because you're
WH11NE- Sunrise: normal. Proton interacts. Right? Very small fraction of protons are interacting in the target. Right? You. Most of your protons are going to interact in the in the in the dump. So anything that's coming out of the dump is likely from a proton at whatever you know, whatever depth that the protons make it through.
WH11NE- Sunrise: whereas so what you you have to be looking for are things that are produced downstream of the dump.
WH11NE- Sunrise: So you know, for Muons, just because things can interact for electrons because you won't see them if they're produced in the dump. So I think that picture that you have. There is not quite right. Yeah, exactly. So that's that's true. I mean this shouldn't, I guess, be extended a little bit farther past the dump. Exactly right?
WH11NE- Sunrise: Yeah. So more ignore that.
WH11NE- Sunrise: So in this picture somewhere for the Duck Center physics somewhere, like after the those being dump in between station one. This is some kind of our decay window, and we are trying to find I mean, those-. Those position will be our trigger our key trigger information to find the I mean to trigger the duck sector.
WH11NE- Sunrise: Do you know what do you remember exactly where the dark photons have been placed.
WH11NE- Sunrise: Is it in composition? Is that all finalized? No, not at all. This is just an illustration where it could be located.
WH11NE- Sunrise: but it'll be near the back. Yeah, it would be farther back. Exactly because you would. You wouldn't want it here, because we can get multiple scattering events, just saturating. And so anything, anything that's past this open aperture? Kmag. That's very unlikely, you know. Get in the dialect signal, for example.
WH11NE- Sunrise: have have there been any like studies to see what like the reach of redact quests would be for different models compared to other experiments.
WH11NE- Sunrise: So there's there's a bunch of very good theory. Papers dedicated exactly to that topic, and I've linked them here as well. But this, for instance, is looking at the dark photon outlook. And so you can see existing constraints from beamed up experiments over here, and then colliders.
WH11NE- Sunrise: bell. And so this is sorry a bit of a conflict or crowded diagram. But, for instance, starquest, and it's in. It's nominal stage. At the time of
WH11NE- Sunrise: of this paper it's projected reach was given by this this purple line right here, which Phaser so, for instance, the Phaser, the forward detector experiment at Cern. Its reach is only here. And so really, this gives because of the spinquest F. Now you get this, you get access to this, this intermediate mixing angle or mixing factor range.
WH11NE- Sunrise: So this is the projection
WH11NE- Sunrise: for darkquest. And it kind of covers this- this interesting space between the collider constraints, there's also reach for others other models. So, for instance, dark, dark scalers where darkquest
WH11NE- Sunrise: performs which we really can see that. I
WH11NE- Sunrise: you can see that for darkquest and some of these these other experiments you can extend this, this the range down to some of the smaller fixed angles. Darkquest is again sorry. It's hard to see. It is.
WH11NE- Sunrise: Yeah. This blue here.
WH11NE- Sunrise: 3rd quest 2 was. So there's we've also been looking to Miller charge particle detectors that could be in the long term future. Added to this, and those would be part of, for instance, the upgrade to our quest which would extend the reach of some of these models even further.
WH11NE- Sunrise: But the nominal darkest would consider installation. And the dark photon photoscopes that are already existing.
WH11NE- Sunrise: When would it run? In theory? Our hope is that it would step at a time.
WH11NE- Sunrise: I mean, when would you hope this begins to the accelerated division? I think everything we are waiting. We are waiting for it. So it really depends on a factory in Germany that makes bushings right? Yeah, I mean, so unfortunately, I think that the last projection I heard was that it would clean.
WH11NE- Sunrise: You know it would take it would start main objective, would resume something in September 26, and then the long shutdown, which I don't think was postponed would begin a couple of months after. So the- the 1st run would not be
WH11NE- Sunrise: stupid long, right?
WH11NE- Sunrise: It's definitely far short of the the initial 2 year. Design goal.
WH11NE- Sunrise: Is that factored in on these? I guess the new.
WH11NE- Sunrise: But like, could you scale your protons on target in your head and like for the previous plot?
WH11NE- Sunrise: Well, let's see. I mean, I should.
WH11NE- Sunrise: Let's go back to the proton. Let's see the the reach at
WH11NE- Sunrise: 10 to the 18. So 10 to the 18 corresponds to 2 years.
WH11NE- Sunrise: Yeah, it would definitely not be.
WH11NE- Sunrise: There are some something you might.
WH11NE- Sunrise: And yeah, and we, I think, and our group are also trying to propose. Yeah, we, we may want to also to establish this- this project to give an optimum shut up
WH11NE- Sunrise: to continue on. But everything is still under discussion. Right?
WH11NE- Sunrise: Okay?
WH11NE- Sunrise: Any more questions.
WH11NE- Sunrise: Okay? If not, we'll take the speaker.