ORNL team builds modular, multidetector system

Scientists from Oak Ridge National Laboratory (ORNL) built the FRIB Decay Station initiator (FDSi) for use at FRIB in the first experiments. FDSi is the initial stage of an FRIB Decay Station (FDS), whose science was envisioned in the 2015 Long Range Plan for Nuclear Science.

FDSi integrates the best detectors currently available in the community for FRIB decay studies. At its core, FDSi is a detection system that receives a beam of rare isotopes and monitors the subsequent decay emissions. Those decay emissions can include charged particles, neutrons, or photons. FDSi is modular and flexible, and the specific configuration of the charged-particle, photon, and neutron detection arrays are dependent on the science goals of each experiment.

Scientists from Argonne National Laboratory (ANL), FRIB, ORNL, and the University of Tennessee Knoxville (UTK) led the collaboration to provide the FDSi instruments needed for the first FRIB scientific user experiment, with participation from members of the larger scientific community who contribute hardware and other resources.

“In designing the FDSi mechanical infrastructure, we placed an emphasis on maximizing the potential of the user community’s existing detector resources and minimizing the time required to reconfigure those resources for optimal performance and scientific output. I believe we have achieved that design goal with the added benefit that the final product is inclusive to multiple institutions. Everyone should be proud of their contribution when the first scientific results are realized,” said James "Mitch" Allmond, staff scientist at ORNL, member of the FDSi coordination committee, project manager of the FDSi project, and co-spokesperson on the first experiment.  

The FDSi experimental program focuses on four strategic areas of FRIB: nuclear structure, nuclear astrophysics, tests of fundamental symmetries, and applications of isotopes for society. FDSi is uniquely positioned for discovery experiments at the extremes of the accessible regions due to the high sensitivity and relatively low beam-rate requirements of decay spectroscopy techniques. In addition, FDSi is able to conduct high-precision measurements for thorough characterization of emergent phenomena, which can be used to benchmark and differentiate between leading theoretical models. FDSi lays the groundwork for a future FDS, which will surpass current generation systems through recent advancements in technology.

The first FRIB experiment will use a unique combination of detectors to enable the first study of an exceptional region of the nuclear chart and performed so comprehensively for the first time. It is a prototypical experiment for future FDS.

“We would like to construct FDS as soon as possible and employ the best detector technologies available to take advantage of the opportunities at FRIB,” said Robert Grzywacz, director of the UT-ORNL Joint Institute for Nuclear Physics & Applications, professor of experimental nuclear physics at UTK, spokesperson for the FDS collaboration, member of the FDSi coordination committee, and co-spokesperson of the first experiment. “With FDS, we hope to cross the current barriers of precision and sensitivity to investigate nuclei that we could only dream of in the past. We expect that FDS and other FRIB instruments will enable paradigm-changing discoveries in nuclear science and open completely new perspectives on how we understand and control the matter on a femtometer scale.”

“It is a privilege to have broad user community engagement in FDSi and that the individual institutions entrust us with their detector systems for experiments at FRIB,” said Sean Liddick, associate professor of chemistry at FRIB and in Michigan State University's Department of Chemistry and FRIB associate director for experimental science, instrument contact for FDSi at FRIB, and a member of the FDSi coordination committee.

The scientific program enabled by FDSi and the eventual FDS is well aligned with the overarching science goals that have been formulated by the broader nuclear science community. FRIB enables scientific research with fast, stopped, and reaccelerated rare isotope beams, supporting a community of 1,600 scientists from around the world.