May 2023
Combining known and unknown physics
“I'm researching hardware for detectors in particle physics, especially neutrino physics. We are currently developing a new experiment. It's called SHiP, which stands for “Search for Hidden Particles”. However, we don't just want to search for previously hidden, new particles, but also take a closer look at known particles, in particular tau neutrinos – and thus combine known and unknown physics.
In Mainz, we are concentrating on a sub-detector, the so-called “Surrounding Background Tagger”, or SBT for short. The central experimental chamber of SHiP is a 50-meter-long vacuum vessel inside which we want to study rare particle decays. To enable a background-free measurement, it is very important that all particles that enter this decay volume from outside are identified – i.e. “tagged”. For this purpose, the SBT encases the entire vacuum vessel with a layer of 20-centimeter-thick liquid scintillator segments equipped with Wavelength-shifting Optical Modules (WOMs) and silicon photomultipliers (SiPM) as readout units. The WOM technology was first proposed for the IceCube experiment: we are working closely with Sebastian Böser's group here at the site to develop it further.
©: Angelika Stehle
In this phase of the experiment, it is possible to contribute your own ideas and thus influence the detector development. We have already been able to carry out four test beam measurements with increasingly sophisticated detector prototypes at CERN and DESY. These are important milestones on the way to the final detector design. Finally, we want to operate SHiP at CERN's SPS proton accelerator: at a future “Beam Dump Facility” (BDF), the high-energy and intense proton beam will be used to produce neutral, heavy particles. Studies of their decays will then allow us to delve deeper into the “HiddenSector”.”
Dr. Annika Hollnagel has been a postdoc in Professor Michael Wurm's group since 2017. She previously completed her PhD in Hamburg on the OPERA experiment, which used a muon neutrino beam to research oscillation in tau and electron neutrinos. In Mainz, she is impressed by how internationally neutrino physics is set up.