” The Muon New Small Wheels (NSW) are the first new detectors in ATLAS specifically developed to deal with high luminosity conditions,” says Andreas Hoecker, ATLAS Spokesperson. “The NSW effort was international, with members from throughout the global ATLAS Collaboration contributing to design and building,” states Philipp Fleischmann, ATLAS Muon System Project Leader. Stephanies impact on the ATLAS experiment extended far beyond the crucial NSW project. She held many essential positions in ATLAS, serving as Muon System Run Coordinator, ATLAS Run Coordinator and, because 2013, as NSW Project Leader.
In her honour– and wishing to fulfil her dream of seeing the NSW installed– a picture of Stephanie was connected to NSW “A” as it was lowered into the experiment.
Credit: CERN
The ATLAS Experiment at CERN welcomes a new detector: the Muon New Small Wheel system. Its successful installation follows almost a decade of style and construction, and marks a significant milestone in ATLAS high-luminosity age.
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) will considerably increase the rate of accidents in the ATLAS experiment. While an opportunity for physicists to explore a few of the rarest processes in deep space, the big collision rate brings brand-new difficulties– in specific, higher radiation levels and substantially more information. The ATLAS Collaboration is adjusting its experiment to deal with these difficulties, updating all parts of its detectors with new, modern instruments.
ATLAS New Small Wheels. Credit: CERN
” The Muon New Small Wheels (NSW) are the very first new detectors in ATLAS specifically created to manage high luminosity conditions,” states Andreas Hoecker, ATLAS Spokesperson. “Todays installation of the second– and last– NSW follows almost a years of devoted efforts from ATLAS members, who designed, built and assembled this modern muon detector from scratch. These brand-new detectors will significantly expand our experiments abilities, readying us for the interesting high luminosities to come.”
Innovative innovation
The ATLAS NSW system is comprised of two wheel-shaped detectors, sitting on opposite ends of the speculative cavern. Called in contrast to ATLAS 25-meter “huge wheel” detectors, each NSW weighs more than 100 tonnes and is nearly 10 meters in diameter.
“This mix of technologies will permit us to study particles at the high rates anticipated from the HL-LHC, while likewise improving our spatial resolution,” states Mario Antonelli, NSW Phase-I Upgrade Project Leader. “This will be particularly important for the ATLAS “trigger,” the system that decides which crash events to keep and which to discard. The trigger will rely on the NSWs excellent resolution to verify whether a particle stemmed from the interaction point, hence lowering our chances of conserving data from unwanted background events.”
Assembly of the NSW chambers at CERN Credit: CERN.
The readout capabilities of the overall system are incredible: two million MM readout channels and 350,000 sTGC electronic readout channels. Each wheel has 16 sectors, each containing 2 layers of MM and sTGC chambers with 4 measurement airplanes each, supplying physicists with beneficial redundancy as they trace a muons track through the detectors
The dance of detectors.
While 2021 has actually seen the NSW detectors journey underground, this was not their first time on the relocation! “The NSW effort was international, with members from across the worldwide ATLAS Collaboration contributing to style and building,” states Philipp Fleischmann, ATLAS Muon System Project Leader.
The first fully-assembled wheel was NSW “A”, finished in May 2021. While work on the second wheel continued at pace, groups right away started strategies to take the detector underground. They were operating under a tight schedule, with the ATLAS and LHC schedule depending on the successful installation of the brand-new wheels.
NSW “A” positioned in place inside the ATLAS experiment. Credit: CERN
Waiting in the wings were the original Small Wheels, which initially had actually to be removed from the ATLAS website to make way for their replacement. Following a years of exceptional service to the experiment, the original wheels were formally retired on July 2 and October 12, and moved to Building 191 on the CERN site.
On July 6, the NSW “A” was driven from Building 191 to the ATLAS surface area hall– a mindful journey of 2 kilometers that lasted several hours. A few months later on, this special event was repeated for NSW “C.” With construction completed in September, the wheel was transported to the ATLAS website on October 14.
NSW “C” goes into the ATLAS surface area hall, located just above the experiment, on 14 October 2021. Credit: CERN
” When we set out to finish the NSW detectors in time for Run 3 of the LHC (beginning next year), we understood it would be a tough assignment,” states Ludovico Pontecorvo, ATLAS Technical Coordinator. “That the group managed to keep the task on track– regardless of an international pandemic and the tragic loss of their job leader, Stephanie Zimmermann– is a testament to their incredible talent and devotion.”
New wheels in movement
The NSW detectors will be crucial in Run 3 data-taking, as a moderate boost in luminosity is currently planned for the LHC. While waiting to see the wheels in action, the ATLAS Collaboration turns their focus to the next major upgrades of the experiment.
Stephanie Zimmermann. Credit: CERN
In memory of Stephanie Zimmermann, ATLAS New Small Wheel Project Leader
Key to the success of the New Small Wheel was its former task leader, ATLAS physicist Stephanie Zimmermann. Her abrupt death in November 2020 left a hole in the tight-knit NSW family. Her associates promised to carry the flag on her behalf, to complete the task in her memory, dedicating themselves to the projects success as entirely as she had.
Stephanies impact on the ATLAS experiment extended far beyond the crucial NSW project. She signed up with the ATLAS experiment as a masters student in 1999, remaining with ATLAS throughout her doctoral thesis, her research study fellowship at CERN, and the subsequent employment as a scientist at the University of Freiburg. As a research study fellow she coordinated the combination work of the muon spectrometer. It was largely thanks to her that this job was finished on time for the setup into the ATLAS underground hall. She held lots of essential positions in ATLAS, acting as Muon System Run Coordinator, ATLAS Run Coordinator and, since 2013, as NSW Project Leader.
She was extremely appreciated for her clinical proficiency, her detailed understanding of every aspect of her projects, her exceptional commitment and group spirit, as well as her support and care for her collaborators. In her honour– and wishing to satisfy her dream of seeing the NSW installed– a picture of Stephanie was attached to NSW “A” as it was reduced into the experiment.
