There was an excellent account of this incident in the book “Atomic Accidents
A History of Nuclear Meltdowns and Disasters; From the Ozark Mountains to Fukushima” by James Mahaffey.
(BTW, the book is amazingly entertaining for such a serious subject! )
In it, he discussed this incident at length, as P8riot mentioned, it is an area of interest to those (such as myself) who have some knowledge and exposure to radioactive isotopes.
In the book, he discusses that some people have speculated that John A. Byrnes, the youngest of the three men, may have been trying to prank the two others by pulling it out faster to get enough emissions to bombard the radiation dectectors and cause them to alarm.
This sounds insane, but this craziness of trying to scare someone by evoking a minute burst of gamma radiation was not unheard of in those days.
One of the pranks people used to play on each other at Los Alamos in the Manhattan project was to manually (using a large flathead screwdriver!!!) separate two halves of a hollow sphere of beryllium around a mass of fissionable material by wedging the flat of the screwdriver between the two halves and gently prying them apart so when the geometry of the sphere changed ever so slightly, it would begin to emit gamma radiation that was enough to trip the radiation detectors and begin emitting the characteristic sound of a geiger counter, which cause some people to nearly crap their pants! Apparently, it was a “trick” more than a few people did to others as a prank to alarm them.
This process was called “Tickling The Dragon”.
This process was discouraged, and there were established ways to do this that did NOT involve the flat head of a screwdriver.
One time, 35 year old Dr. Louis Slotin (a relatively young nuclear physicist) was demonstrating how to do this manually to an associate, bypassing all the safety precautions that would prevent an accident, and when he pried the heavy sphere apart with the screwdriver, the flat head of the screwdriver slipped and the entire upper sphere displaced and a fully critical radioactive event occurred.
There was a blue flash in the room (called Cherenkov Radiation) and Slotin knew exactly what happened and immediately put the two halves back together with his bare hands. He died an agonizing death which took nine days, and his hands and arms, which had severe vascular damage began to die and rot because they could get no blood.
There was speculation that at the SL-1 reactor that day, the young Byrnes wanted to tease the older Navy veteran Seabee Richard C. Legg (who was the team supervisor) by causing the alarm to go off. They speculated it was hard to pull up, so he gave it a good tug, and it came up all the way, with disastrous results.
Pretty grim stuff.
No, the “Demon” core incidents - there were actually two - had nothing to do with a “prank”. It was a field expedient way around established precautions.
Slotin in particular was well known to be complacent, a bit reckless and not a strict adherent to nuclear safety or established procedure, and it killed him.
“Tickling the dragon” was yet another procedure entirely. It was a bit insane but they knew what they were doing.
I just finished reading the book, American Prometheus, which is what a lot folks consider to be the best biography of J. Robert Oppenheimer, Director of the Los Alamos Lab. There was no mention of the Slotin incident in the book.