The Manhattan Project Files: The Demon Core

The Manhattan Project Files: The Demon Core

A Story by Maddy Tarbox

A short story about an accident involving Louis Slotin, who died due to a mishap with an atomic bomb core. This happened during WWII.


Robert Bacher

May 21st, 1946, 5:24 AM

�" For some reason, I can’t stop thinking about Henry. The accident happened with CD. Henry lasted for 25 days, and died at 24 years old. �"

  There’s nothing unusual about today. Everyone’s up before our 6:00 breakfast, and the labs are buzzing with activity. Like always, it’s going to be pretty hot here in Los Alamos. All the scientists are doing their thing; tests are running well, and progress is being made. However, today we have a scheduled demonstration of criticality testing with Core-D (CD). Since this is Louis’s main job, he will be running the demonstration. I’m nervous for the demo even though I know everything’s going to be okay; he’s done this test at least 12 times, if not more. Still, I can’t shake off this feeling of nervousness, I don’t know why. It’s probably just last night’s dinner coming back to haunt me.

I have tremendous faith in Louis, even though I don’t agree with his style. He comes across with bravado...he’s slightly narcissistic�"that’s what he is. He’s quite casual, but sharp as a tack. I usually see him in his trademark look: jeans and cowboy boots. We’ve even got a nickname for the work he does. We call it, “tickling the tail of a sleeping dragon”. As long as CD (the dragon’s name) doesn’t wake up, you’ll be “safe”.

There was one who did wake CD. His name was Henry. He was piling tungsten-carbide bricks around the core, and he…he dropped one right onto it. When the brick came into contact with the core, it caused CD to go critical. Emitting neutrons and delayed gamma rays (at the very least), Henry received high doses of radiation. He wouldn’t have died if he hadn’t stayed to disassemble the experiment. He received beta burns, and quickly collapsed with acute radiation poisoning.

I don’t know what he was thinking at the time, the feeling must have been absolutely horrifying, beyond horrifying. The very instant that brick tumbled out of his hand, he knew. He knew that he was going to die. Thinking, “what would have happened had I not dropped that brick?” The answers are infinite, and many years could be spent formulating answers to that one question.

I think I need to stop stressing about Henry and focus on what’s important right now: Louis’s demonstration. I know he’s going to do just fine. He’s done this so many times; he could do it with his eyes closed.  Today’s going to go just like any other day.

“Louis, there you are! I’ve been looking for you all over this damned facility. I didn’t see you at breakfast today. Where were you?” I asked.

“Oh you know, same old, same old. I’ve been up since 4, preparing CD for more testing. Today’s a special day! I’ve got people watching me so I have a just a smidge of stage fright�"but it’s nothing worth worrying about.” Louis answered.

“Right! You have your demonstration today. How are you feeling about it?  I mean, there’s practically nothing to worry about--you’ve done this how many times now?” I asked.

Louis shrugged casually, looking at the ground. “Don’t worry Robert, I’m certainly not worrying.”

I opened my mouth to ask him how his family was doing, but he interrupted, “Sorry Robert, I have to get back to my lab. I don’t want anyone poking his head into the dragon’s lair. Things have the potential to be quite dangerous.”

I chuckled, and waved him on his way.

I watched Louis walk down the hall to his lab, seeing him acknowledge the presence of a small group of scientists clustered by the piano. As he passed, I heard pieces and fragments of their whispered gossip: ‘that Louis has the mental drive of no one I’ve ever known before! He works day after day, hardly taking a break. How in Hell does he do it?’ ‘I heard that he was so jealous of Daghlian’s work, that he rigged CD so there would be an accident.’Oh don’t be ridiculous now! We all know that’s a downright lie.’

I sighed to myself, ‘People will be people.’




‘Where on earth did I place that screwdriver?’ I muttered to myself. ‘Right…I placed it by my bedside table.’ I briskly walked through the hallway to our living quarters, and entered my bedroom. I looked around and nothing seemed out of place; everything was as I left it. ‘What time is it?’ I wondered. I looked up at my clock. 6:53 AM.  ‘I still have plenty of time before my demo. I don’t need to get to work right now.’ I looked down at my unmade bed, at the pillowcases half hanging off of my pillows. I grabbed a pillow and gave a half-assed attempt to shove it back inside. ‘You’re stressing about something Louis…you know that you’re stressed whenever you start cleaning things up.’ I think to myself.

I walked away from my unkempt bed and went up to my window. There’s nothing outside. Just dust. It’s always hot and dry outside, but I still see water everywhere. They’re just mirages, illusions, things that aren’t really there. It’s so easy to overlook something here, to misjudge, and to almost forget. I didn’t sleep well last night…I think I have enough time to get in a quick nap before the demonstration. I think that would be a good idea; I need to be alert while performing this.  

I walked back over to my bed and picked up my half covered pillow from the floor, dusted it off, and threw it back onto the bed. I tried to kick off my boots, but I didn’t have the energy, so I gave up and sat down on the bed.

I was very tired, but I just couldn’t fall asleep. Something was bothering me, but I couldn’t pinpoint what it was. I looked back at my clock. 6:59 AM.It’s been 6 minutes since I came into my room. Why does it feel like 6 hours?’ As I lay thinking about my distorted perception of time, I went on a thought spiral, which distracted me enough to drift into sleep.

‘Good god, where am I? What time is it?’ I look over to my clock, only to see that it had been replaced by a kerosene lamp. I pick it up, surprised by how light it is. ‘It’s empty.’

‘Of course it is, we used it all up months ago,’ a voice says. I bring the lamp up close to my face and see that there’s something inscribed into it. I adjust my glasses, and use my sleeve to wipe off the accumulated dust. “August 21st, 1945” it reads. There’s something else on the lamp, but it disintegrates in my hands.

‘August 21st…why that particular day?’ I mumble to myself.

‘Don’t you remember, Louis? Don’t you remember what happened with him?’ the voice asks.

‘Who is him? Who or what are you? Where am I?’ I call out.

‘’He’ is Henry. Henry Daghlian. Don’t ask questions you know the answer to.’ it retorts.

I turn around and I see something shift out of the corner of my eye. The kerosene lamp is back, but something isn’t right about it. The image of it isn’t stable; it’s like a flickering light bulb. I look down at my feet and I realize that I’m not where I think I am. I look under my feet. I see a small glowing plume of some kind. I don’t know what it is…it looks like a molten cloud. It’s billowing up, growing larger with each passing second, getting faster each moment. Every shade of blues, greens, and yellows all mixed together in one event. I try to move my neck so I can look deeper into the hypnotizing glow of the cloud, but I can’t move. I’m stuck. The hues look a little less beautiful, the heat isn’t as pleasantly warm as before. ‘Something isn’t right, I need to get out, let me out, LET ME OUT.’

I can’t move. I’m stuck. I struggle to free myself from whatever the hell’s gotten into me. It’s getting blindingly bright, and my hairs are starting to scorch. I take one panicked look below me, and I retch in horror. It’s so hot I can taste the fire; it’s so bright I can hear the light. I see Henry’s face. I scream.


        In a panicked spasm, I jolt awake, feeling less rested than I was before I fell asleep. ‘Good God, what time is it?’ I mumble to myself.

I look over to my clock. 7:42 AM. The clock’s still there. Why is the clock there? ‘Oh my god…my dream…the kerosene lamp.’  

I throw off my blankets and scramble over to my desk with the clock. There’s no kerosene lamp on my desk, so I grab the edge of my desk, and push with all my strength. The desk moves a little bit, so I continue to push. After about a minute of this, the desk is far away enough from the wall to allow my arm to fit. I grab my backup lamp and shine it into the dark and dusty crevasse. There’s an assortment of objects I’ve long since forgotten about, but there’s no kerosene lamp. I think back to my dream, which is quickly fading, and I try to remember what was so important about the lamp. ‘I only remember that it had something to do with Henry Daghlian.’




        “Alright ladies and gentlemen,” says Louis, “what I’m about to do before you is something that I’ve done a dozen times before. My job consists of dangerous criticality testing, but this is not a test, but rather, a demonstration. I first used uranium with Otto Frisch’s experiments. What I’m working with now is not uranium, it’s plutonium. Is this clear to you all, or do I need to set up a review?”

        The audience of seven scientists shake their heads.

“Right before me is a 6.2 kilogram, 3.5 inch diameter subcritical mass of plutonium,” Louis casually remarks. “Oh, and did I mention that I assembled the core for the Trinity test?” he boasted. “I’m known as the “chief armorer of the United States” due to my expertise in assembling nuclear weapons.”

        “There he goes again, that Louis is quite full of himself. I mean he’s fantastic at what he does, but don’t tell him that, he doesn’t need anymore ego-boosting.” I mutter to the person next to me.

“You said it Robert, he doesn’t even try to hide his ego. Unbelievable.”

I think back to how Louis sometimes doesn’t follow protocol, and I mumble, “He had better follow proper protocol while giving this demonstration.”

We turn our attention back to Louis.

“Thanks to the insightful Robert Bacher, I was chosen to work in the bomb physics group.  I’ve been here since December of 1944, and have been making steady progress ever since.” Louis rambles on, “Now, I don’t want any of you think I’m stalling, so here it goes. Please be quiet, and don’t make any sudden movements.”



        Okay, there’s nothing to stress about. There are only seven people here, and all I’m doing is conducting an experiment to verify the exact point at which a subcritical mass of fissile material could be made critical by the positioning of neutron reflectors.‘  I think to myself. ‘Stop stressing Louis! Come on; just play Glenn Miller’s ‘In the Mood’ in your head. That always relaxes you.’  

I take a deep breath and look out at my seven colleagues. I look down at the core, and I see one of the two half-spheres of beryllium on the table beside me. With my screwdriver in my left hand, I place it on the edge of the half-sphere under the core. I make sure that it’s stable and in place, and I reach for the other half-sphere. The screwdriver is still in the right position, so I begin to lower the top reflector into place. Everyone’s watching right now, and holding their breath. I focus all of my attention onto the top reflector and

        �"Something feels wrong. I can see the top reflector lowering in slow motion; the screwdriver is still there preventing the formation of a critical mass. Is it the screwdriver? I’m still lowering the top reflector, I’ve got good control of it…and I’m holding it by the thumbhole. I’m setting it down on top of the screwdriver now and�"*SHATTER*�"the sudden sound causes me to jump�"

Instantly there’s a blinding flash of blue light; I can feel the scorching temperature of a heat wave.

My reaction is instantaneous, “CRITICAL, EVERYONE GET DOWN!”

I quickly flip the top shell onto the floor, but it’s too late. There has been a reaction.  ‘Sonofabitch, I told everyone to be SILENT,’ I yell, ‘Now what in HELL WAS THAT?!

I looked out to the small group, and I feel a wave of horror come over me. “NOBODY MOVE. Everyone, drop everything metal you have right now where you’re standing, and get out of this room now.”

Everyone quickly did as I said, and as the last person rushed out of the room, I opened my mouth to apologize, but my legs gave out from underneath me. I collapsed, convulsing, and I blacked out.

I see a small glowing plume of some kind. I don’t know what it is…it looks like a molten cloud. It’s billowing up, growing larger with each passing second, getting faster each moment. Every shade of blues, greens, and yellows all mixed together in one event. I try to move my neck so I can look deeper into the hypnotizing glow of the cloud, but I can’t move. I’m stuck. The hues looks a little less beautiful, the heat isn’t as pleasantly warm as before. ‘Something isn’t right, I need to get out, let me out, LET ME OUT.’ I can’t move. I’m stuck. I struggle to free myself from whatever the hell’s gotten into me. I’m blind. My body is on fire. I retch in horror. It’s so hot I can taste the fire; it’s so bright I’ve become the light. I see Henry’s face. I scream.


Robert Bacher

May 30th, 1946, 6:18 PM

�"There’s no other name for it. It’s killed 2 people within a year. We now refer to it as the Demon Core. �"

I just re-read through my journal entry from May 21st, and I cringe at how naïve I was. I knew something wasn’t right. I had that gut feeling that tells me when something bad is going to happen, but I just dismissed it. Louis died today, 9 days after the incident. There is some confusion about what exactly happened, but we do have ideas.

  Louis used only a screwdriver to prevent the half-spheres from joining together. His screwdriver slipped out by a fraction of an inch when he was lowering the top reflector down, accidentally beginning a fission reaction, this released a burst of hard radiation. He quickly flipped the top shell to the floor, which stopped the heating of the core and shells, and stopped the criticality within seconds of initiation. His reaction prevented a recurrence and ended the accident. He was positioned in a way that shielded us from most of the neutron radiation, but he received a dose of 1000 rads of neutron and 113 rads gamma radiation, and died 9 days later from acute radiation poisoning.

This is the second death due to an accident involving this particular plutonium core. We now refer to it as the Demon Core.


The Demon Core got it’s name after the occurrence of two criticality accidents. Two people, Henry Daghlian and Louis Slotin, were killed. Henry dropped a tungsten-carbide brick onto the core, and Louis’s screwdriver slipped out from between the two beryllium half-spheres.

This core was to be used in the 3rd atomic bomb used on Japan in World War II. This never happened, and the bomb was instead used in the first atomic bomb test after World War II, only 5 weeks after the second criticality accident. The test ran well, the bomb performed normally with the same explosive yield as the next core used in this set of 2 tests.

© 2016 Maddy Tarbox

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Added on May 13, 2016
Last Updated on May 13, 2016
Tags: manhattan, project, louis, slotin, atom, atomic, bomb, tungsten, carbide, core, death, accident, criticality, radiation, radioactive


Maddy Tarbox
Maddy Tarbox


17 years old! I don't normally write but every now and then I enjoy it. more..