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The Deep Underground Neutrino Experiment (DUNE), a worldwide flagship experiment being placed in the Long-Baseline Neutrino Facility in the US, is intended to shed light on neutrinos’ riddles. By improving our knowledge of neutrino behavior, it is intended that the experiment will provide a clearer picture of how the Universe functions.

The experiment will take place at the Illinois-based Fermi National Acceleratory Laboratory (Fermilab), which is run by the US Department of Energy. Massive neutrino detectors will make up DUNE, and a neutrino beam will travel 800 miles from Fermilab to the Sanford Underground Research Facility, where it will hit its objective.

Over 1,400 scientists and engineers from all over the world are collaborating to the experiment since it is such a complicated and technological undertaking that calls for significant international collaboration. The UK is a vital partner in the experiment since it is providing the anode plane assemblies, which are essential parts for the DUNE Far Detector (APAs). The parts are being constructed at Sci-Tech Daresbury, the Daresbury Laboratory of the Science and Technology Facilities Council (STFC), in the Liverpool City Region.

The project’s scientific leadership is provided by physicists from the universities of Liverpool and Manchester. Due of the enormous size of the APAs and the high quantity (150) needed for DUNE, a sizable plant was developed specifically for APA production at Daresbury inside a decommissioned accelerator hall. Editor Georgie Purcell met with Justin Evans from the University of Manchester, who is significantly involved in the APA creation process, to learn more about the capabilities of the APAs and the UK’s participation in DUNE.


Summarising the UK’s involvement in DUNE

DUNE involves the UK significantly because we are one of the project’s largest international partners. The anode plane assemblies, which I am most closely working with, is one of the high-profile contributions the UK is giving to DUNE (APAs). These are the detector’s primary readout tools. To begin, let me simply define an anode plane. The APAs will be put in the first of four modules for the DUNE detector. 17.5 kilotonnes of liquid argon will be stored in the first module, which will be one mile below in a cryostat. When the neutrinos from Fermilab impacted the argon, charged particles like protons, electrons, and muons were created. The neutrinos ionize the argon as they pass through it, removing the electrons from the argon atoms and leaving free electrons floating around in the argon. That is everything you need in order to visualize the muon, pion, and proton motions as well as the neutrino reaction. The negative electrons are moved from the cathode to the anode by applying 180,000 volts across this tank of liquid argon.

A 58-meter long and 12-meter-high anode plane covers the cryostat’s interior walls. In essence, we want to cover that wall with a grid of wires so that when electrons strike the wall, we can determine which wires they hit from the grid of wires. This grid of wires then behaves like the pixels of a charge-coupled device (CCD) camera, essentially taking a picture of the electrons inside the argon. We are creating similar readout walls; however we are unable to construct a wall measuring 12 m by 58 m since the detector must be buried. As a result, we are building 2.3 x 6 m rectangular steel panels that are covered in 3,500 150 micron-diameter wires. The electrons are captured by these long wires. To extract the data from the detector, the next step is to electronically weave those electrons out. We are constructing 150 of these APAs altogether, which will finally comprise the necessary walls.

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The data acquisition system, which deals with the data flow out of a detector, is also being delivered by the UK. It consists of computer hardware and supporting software. Huge volumes of electrical data are being produced by the anode planes, and eventually, we will capture 30 petabytes of data from the DUNE detector annually. Therefore, we require an intelligent system that only retains data when anything important occurs. The data collecting system fills this demand. It must constantly check the detector to see, for instance, if a neutrino has passed through it. When anything intriguing occurs, a variety of sophisticated algorithms send the signal that activates the detector, turning it on and storing data. Given that you don’t want to miss anything crucial, it must be sophisticated enough to only read something out when something noteworthy is happening. When DUNE is turned on, for instance, we might only detect one of the neutrinos from supernovas that we are hoping to look for.

We are also contributing a great deal of physics expertise. Pattern recognition algorithms are one specific UK deliverable that offers an automated data analysis way to examine what occurs when the neutrinos impact something. The development of the industry-recognized pattern recognition program Pandora for liquid argon was spearheaded by the UK. The UK also contributes to the accelerator in addition to the detector. The accelerator beam originating from Fermilab is known as the Long Baseline Neutrino Facility, and DUNE is the detector (LBNF). The UK has enormous experience in accelerator technology, not simply detector technology, especially in our national labs. By speeding protons to high energies and smashing them against a target—a chunk of graphite—the accelerator at Fermilab is being improved to produce an extremely strong neutrino beam. At some point after the impact, neutrinos are created. The accelerator will receive two things from the UK. The protons are accelerated to high energy in the first method, cavities. The graphite target, which the protons strike to produce neutrinos, is also supplied by the UK. This is a significant piece of expertise because this piece of graphite will be struck by protons irradiated in a high radiation environment for many years, necessitating that it be extremely robust and maintain its coolness.


What knowledge can the UK provide to DUNE?

The UK has a long history of making top-tier contributions to important particle physics experiments, especially in the area of neutrino physics. For the Large Hadron Collider (LHC), for instance, many of our academic groups and labs constructed key detector components, including as the ATLAS, LHCb, and CMS detectors. We have a wide range of academic professionals who are knowledgeable about the specifics of detector technology because we constructed significant detector components for earlier neutrino investigations in America and Japan. It is not limited to academics, though. The national laboratories and colleges have a wealth of technical knowledge. We have technicians, mechanical engineers, and electrical engineers that are aware of the requirements necessary to construct this advanced technology on a wide scale. On a significant scale for construction, we are executing custom engineering. A crucial contribution from the UK to DUNE is having this technological know-how at the universities because building something the size of a cathedral demands a unique skill set.

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We have a strong history in neutrino physics as well. Many of us who are working on DUNE have conducted assessments of earlier American or Japanese experiments that provided information about the behavior of neutrinos. In particular, we have led some of the most important measurements of neutrinos’ behavior and interactions with matter. We also have a great deal of experience with liquid argon. A liquid argon detector is called DUNE. Although it is the largest one to ever be constructed, it is not the first one. Liquid argon has been used successfully in other tests, supporting this new investigation. For instance, I also serve as the Co-Spokesperson for the MicroBooNE experiment, a smaller liquid argon detector, in addition to my duties with DUNE. It is considerably smaller than DUNE, but it was the first relatively sized liquid argon time projection chamber (TPC) to run for a considerable amount of time. This demonstrated that the detector could be run steadily for more than five years while still enabling top-notch neutrino physics. As part of MicroBooNE, numerous methods and devices that we will employ for DUNE were developed, including the algorithm for pattern recognition called Pandora.


What development has there been with the APA elements in 2022?

2022 was a significant year for us since we entered a phase of mass production. Between now and the beginning of 2027, we must construct 150 APAs. To accomplish this, we’ve built a 1,000m2 production facility at the Daresbury laboratory with four enormous winding machines that hold the 6m x 2.3m frames and wind 3,500 wires around them to connect them to the electronics. All four of these production lines are now operational, compared to just one at the beginning of the year. The process has evolved over the course of the year from commissioning the factory, discovering the quirks of the machine, getting it up and running, commissioning the machine, and beginning to teach our personnel on how to use it to the point where four teams are currently operating concurrently. In addition to the setup, we have been employing a group of individuals and teaching them in the factory to independently operate extremely specialized machinery and construct particle detectors. In the northwest of England, where we have created jobs, technicians who have no prior knowledge of particle physics are being hired and trained to construct a particle detector.

And we’ve been working hard to forge lasting bonds with our supply chain partners. We purchase the steel used in the construction of these APAs from a manufacturer in the Sunderland area. Additionally, a business in North Wales will provide us with the approximately 40,000 electronics boards we need to install on the APAs for the entire production operation. These are just two instances, but the fact that these multimillion-pound agreements were made and signed this year was essential to guaranteeing the plant would receive materials throughout the project at CERN, we also completed a final prototype this year. A final prototype was also built to ensure that the parts we are building in the UK fit together with the parts our international partners are building, such as photon detectors and readout electronics. We built an initial prototype back in 2018 to demonstrate that the detector worked before we started production. We feel we have made significant progress this year and are now in the period of mass production.

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Have there been any big obstacles you’ve had to overcome thus far in the process? If so, how?

Large challenges, yes. This project had to be set up during the COVID-19 pandemic, and it is difficult to organize a large construction project with international partners during a pandemic. For instance, the global lockdowns were implemented at the same time that we were constructing the 1,000-square-metre facility in Daresbury, which undoubtedly slowed the process down. But we had to keep going, work on things, and bring people back into the lab as soon as we could. The procedure was challenging because we couldn’t visit our suppliers because we were just beginning to build relationships with them at the time of the lockdown. Additionally, we were unable to collaborate with international engineers at Fermilab and CERN in the same manner as before. Therefore, we made extensive use of video conference calls and returned to work as soon as the constraints would allow.

We are fortunate to have a team of highly motivated, skilled individuals who go above and beyond to accomplish their goals. With one specialist in the factory and everyone else online attempting to troubleshoot remotely, we were guiding individuals through setups via video call. We also had to figure out ways to speed things up because lockdown was slowing things down. To make up for the time we missed due to lockdown constraints, we are now considering purchasing a fifth winder. Doing this during a time of inflation is a significant additional barrier because everything has seen a sharp increase in price. We estimated the study in 2019 after receiving a funding from UK Research and Innovation (UKRI) right before the pandemic. However, throughout the pandemic, expenses for international transportation, steel, and production in general went up. As a result, we had to carefully consider our designs and look globally for the most affordable suppliers in order to identify ways to cut expenses. Then, as we were attempting to construct something at CERN, Brexit occurred, posing further logistical and financial difficulties.


What is the collaboration’s next step, and what goals do you have for the near future?

The project is entering the mass production stage internationally. Up until the beginning of 2027, the UK will continue to produce APAs. Our global partners are moving into the stage of mass production for many other components, such as photon detectors, readout electronics, and the detector structure, elsewhere. We are also tackling the logistics of getting this detector down, such as moving the components to South Dakota precisely when it has to go underground because it is a logistical headache to get everything underground at the appropriate moment when using a single mile-deep mineshaft.

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