Particle accelerators are built horizontally for practical reasons related to their design and operation. Here are a few reasons for this choice:
Space Constraints: Particle accelerators are complex and large-scale scientific instruments. Building them horizontally allows for efficient use of space, especially in underground facilities where space may be limited. By extending the accelerator in a horizontal direction, it can cover a larger area without requiring excessive vertical space.
Beam Guiding and Bending: Particle accelerators use magnetic fields to guide and bend particle beams along their desired trajectories. By arranging the accelerator in a horizontal plane, it becomes easier to design and control the magnetic field configurations to steer the particles in the desired path.
Alignment and Stability: Horizontal alignment of the accelerator components simplifies the alignment and stability requirements. It is generally easier to ensure the straightness and alignment of components along the horizontal plane, which helps maintain the precision needed for the particles to follow their desired paths accurately.
Support and Access: Building the accelerator horizontally allows for easier access to the various components, such as magnets, beam diagnostics, and detectors, for maintenance, repairs, and upgrades. Horizontal arrangement provides convenient access points along the length of the accelerator.
It's important to note that not all particle accelerators are built horizontally. There are also vertical or inclined accelerators, depending on specific scientific goals and design considerations. For example, some medical linear accelerators used for cancer treatment are vertically oriented. However, for many high-energy research accelerators, the horizontal arrangement is the most commonly adopted configuration due to its practical advantages.