Targets
Targets in particle accelerators are materials or devices that the particle beams strike to induce reactions or generate secondary particles. These interactions are crucial for various applications, such as producing medical isotopes, studying nuclear reactions, or generating neutrons for material analysis. The design and composition of targets depend on the specific requirements of the experiments.
Types
Solid Metallic Targets
Solid metallic targets are made from materials like tungsten, tantalum, lead, zinc and beryllium, which enables them to withstand intense beams and high thermal loads. This type is primarily used for medical isotope production (e.g., Mo-99), neutron generation, and semiconductor ion implantation.
Liquid Targets
Liquid targets, such as enriched water or gallium, excel in applications requiring efficient heat dissipation and uniform material interaction. Commonly used for producing isotopes like fluorine-18 and in proton therapy research, they are adaptable for medical and research settings.
Gas Targets
Contained or flowing gas targets, including hydrogen, helium, and neon, enable high-precision nuclear reactions and isotope production (e.g., carbon-11). Their low density and scalability suit applications in medical imaging and fundamental nuclear research while minimizing material contamination.
Composite Targets
Composite targets integrate layered materials, such as uranium-tungsten combinations, to optimize reaction yields and thermal management. These versatile designs are useful for spallation neutron sources and advanced nuclear studies.
Crystal and Thin Foil Targets
Thin foil and crystal targets use materials like diamond or silicon. They facilitate low-interference particle interactions which is ideal for high-energy physics experiments, electron diffraction, and gamma-ray generation.
Powder Targets
Powdered targets (such as fluidized tungsten powder) offer innovative solutions for increasingly high-powered accelerator applications. When subjected to proton beams, they exhibit less violent ejection compared to liquid targets.
Biological and Organic Targets
Organic or biological targets, such as gelatin phantoms or tissue-equivalent materials, replicate living tissue for radiobiology and therapy research. They allow for better studies on radiation effects and calibration of medical radiation techniques.
Books
Preparation of Nuclear Targets for Particle Accelerators – J. Jaklovsky
Articles
Solid Targetry Systems: A Brief History – W. Gelbart
Materials considerations in accelerator targets – H. Peacock
Observed proton beam induced disruption of a tungsten powder sample at CERN – T. Davenne
High Power Targetry R&D and support for future generation accelerator – F. Pellemoine
Thermomechanical design of a static gas target for electron accelerators – B. Brajuskovic
Design and Optimization of the Target in Electron Linear Accelerator – Q. Gao
Tissue mimicking materials for imaging and therapy phantoms: a review – C. McGarry
Presentations
IAEA: Production of fluorine‐18 with a cyclotron
Podcasts/Videos
Accelerator Science: Collider vs. Fixed Target – Fermilab
Targets in Nuclear Physics: James Maxwell – Jefferson Lab