Only if Krypton is a proper noun, and then only Krypton, not experiment.
The krypton experiment was used as a source – if krypton is an element.
The Krypton experiment was used as a source – if based on the process of Professor Krypton.
the Stanford prison experiment
Capitalization exceptions are the title of a paper or film or software, or just before establishing an acronym: The Stanford Prison Experiment (SPE)
Also see the names of specific benchmark tests. The word "benchmark" is uncapitalized except where it is part of a product name.