Which artifact results from two closely spaced reflectors and appears as a dense tail behind the reflector?

• A. Comet Tail
• B. Ring Down
• C. Side Lobes
• D. Focal Banding

Answer: (A)

This is the comet tail artifact. It shows up when two closely spaced reflectors create a sequence of echoes that arrive so near in time that the system merges them into a single, dense, bright tail extending behind the actual reflector. The close spacing between reflectors causes multiple rapid reverberations, which stack into a trailing line that looks like a comet’s tail.

Ring down, by contrast, comes from gas bubbles resonating and produces a continuous bright stripe associated with the bubble itself, not a tail behind a reflector. Side lobes are energy from outside the main beam that can create additional echoes around structures, not a dense trailing artifact directly behind a reflector. Focal banding relates to brightness variations caused by focusing and beam profile effects, not a trailing dense tail from closely spaced reflectors.