Bob Zwaska, head of the newly formed Target Systems Department, wrote this column.
On Monday, Feb. 9, Chief Accelerator Officer Sergei Nagaitsev formally instituted the Target Systems Department within the Accelerator Division of Fermilab. The TSD will design, construct and operate high-intensity target facilities and their associated systems and components for research with intense particle beams at Fermilab. It will also conduct fundamental and applied research and development to build and maintain expertise in target-related technologies as a core competency for experiments and facilities making use of high-intensity, high-energy particle beams. The TSD workforce consists of technicians, engineers and physicists with experience and responsibility in high-intensity target facilities.
All present accelerator-based experiments at Fermilab use targets. The target converts the high-energy proton beam from the accelerator complex into new particles (generally through the strong interaction). The proton beams produced in the synchrotrons are not ends in themselves. Only when new particles are created from the protons does it become interesting for particle physics. Fixed-target experiments are very efficient ways of producing particles though high-energy interactions, consuming almost all of the proton beam.
High-intensity fixed-target facilities provide unique challenges. The beam components must be able to withstand sustained, high-power proton beams, which cause stresses, heating and eventually radiation damage and corrosion of materials. The target itself must sit directly in the beam, and generally it is advantageous to squeeze the beam to a small size, sharpening the stresses inflicted on the target. Furthermore, other devices such as magnets and instrumentation must reside near the target, suffering similar effects as the targets.
The Target Systems Department will integrate the phases and functions of high-intensity facilities. TSD will be the repository of knowledge for specialized devices such as targets, horns, lenses, windows, absorbers, collimators and shield piles. TSD’s activities will span all of Fermilab’s high-intensity facilities, currently NuMI and the Booster Neutrino Beamline, in the near future Muon g-2 and Mu2e, and eventually LBNF/DUNE and other future experiments. TSD’s involvement in these devices and facilities will start with R&D, continue through design, construction and operation, and eventually conclude with remote handling and disposal.
Future facilities at Fermilab, particularly those based on PIP-II and other future accelerators, will be possible only with advances in the technologies and materials of targets and other devices within the target facility. Just in the last few weeks the accelerators started producing record intensity beam powers for NuMI, and we expect to reach 700 kilowatts over the next year or so. The High-Power Targetry program within TSD will address these challenges through focused research and development. This program was recently highlighted as the number one recommendation of the HEPAP Accelerator R&D panel. A major component of this program is the RaDIATE collaboration to examine materials, which will be the subject of a future column by Patrick Hurh.
The establishment of a Target Systems Department orients the Accelerator Division toward Fermilab’s current portfolio of experiments, and those for the foreseeable future. The issues regarding targets will only become greater as time goes on and beam powers increase. TSD will maintain and propel Fermilab’s expertise needed for future experiments.