SBND’s cosmic ray tagger begins taking data

Members of the Short-Baseline Near Detector collaboration install the cosmic ray tagger in the SBND building. The cosmic ray tagger is made of the shiny, rectangular panels on the building floor. Photo: Reidar Hahn

On the morning of June 22, an important component of the Short-Baseline Near Detector (SBND) began taking data.

The component, called the cosmic ray tagger, is the first of SBND’s subdetectors to be completed and operational.

The SBND collaboration is constructing the Short-Baseline Near Detector piece by piece, and with the completion of the cosmic ray tagger, we’ve reached a construction and operations milestone.

The SBND’s sought-after particle is the neutrino — a fleeting, difficult-to-capture particle. Adding to the difficulty is the fact that cosmic rays from outer space cloud the sought-after neutrino signal in the detector. The cosmic ray tagger, or CRT, is designed to identify the cosmic rays that rain down on the detector so scientists can subtract those traces from their data, revealing the neutrino signal.

By functionality it is similar to the one installed earlier at the MicroBooNE detector, which you may have read about.

The SBND collaboration installed and commissioned the cosmic ray tagger this month — in only two weeks. The CRT is composed of many finely grained modules capable of measuring an interaction instance to the nanosecond and to within a centimeter of its location in the CRT.

With the newly operational cosmic ray tagger in its current configuration, SBND is currently characterizing the flux of particles called muons. These muons are produced by neutrinos from the Booster Neutrino Beamline so that scientists can measure their parameters in the SBND pit, where SBND will be built. Data taken during this characterization stage will be a great asset on the way to simulation and analysis for the whole SBND detector later on.

The collaboration will continue to take data using the beam from the Booster Neutrino Beamline, as well as from cosmic rays, until the accelerator shutdown in July. When the accelerator complex restarts in October, we will restart data-taking using the CRT.

We are grateful to collaborators at the University of Bern who designed and produced the CRT modules. And the swift installation and commissioning was possible thanks only to the tremendous dedication and commitment of many colleagues from the SBND collaboration as well as great support from Fermilab technical personnel.

Igor Kreslo is a member of the SBND collaboration and a professor at Albert Einstein Center for Fundamental Physics, University of Bern.