In this 1967 novel by William F. Nolan and George Clayton Johnson, individuals live for 21 years, before voluntarily ending their lives in a ritual called "Carrousel" where the body is vaporized, with the hope of being born again (spoiler alert: no one is ever reborn). In the 1976 film adaptation, Carrousel is shown, but the age of mandatory death is moved back to 30.
Identify ...
the novel or film of the same title
.Logan's Run