Is an antimatter bomb feasible?

  • Thread starter Tghu Verd
  • Start date
217
88
If your plot requires that characters carry something in
It does, but they are literally like SWAT, carefully entering a hostile building, so the AM bomb looks like a bomb, I don't need to disguise it. So to the protagonist it looks like "an overlarge insulated water bottle tipped on its side" which already contains the AM.
 
217
88
You're not going to be able to store grams of antimatter in an ion trap for the same reason you can't store grams of matter in an ion trap.
This I don't get, @Vanadium 50. Apparently a Penning trap is used to store AM at CERN, so I'm clearly missing something (which is entirely likely, I'm way outside my knowledge zone!). How would you store AM for periods of months to a few years?
 

Vanadium 50

Staff Emeritus
Science Advisor
Education Advisor
23,099
5,386
Let's focus on matter for the moment. If I use an ion trap to store a gram of ionized hydrogen in the size of a water bottle (say a sphere 20cm on a side?) that works out to a charge of 100,000 C, a potential of 5 trillion volts, and a stored energy of 60 kilotons.

This is impossible: 5 trillion volts is enough - way, way more than you need - to turn the Penning trap itself into a puff of plasma.

You can store a few atoms in a trap. Not anything macroscopic.
 

Vanadium 50

Staff Emeritus
Science Advisor
Education Advisor
23,099
5,386
Phinds, you think that's informative? Ask yourself how much more destructive it would be if I swapped antimatter for matter?

About 50% more. That's right - antimatter ions (in this hypothetical configuration) are more dangerous because they are ions than they are because they're antimatter.
 
217
88
that works out to a charge of 100,000 C, a potential of 5 trillion volts, and a stored energy of 60 kilotons.
Ah, yeah, that's not practical. Let me think this through because discussing the whole concept here has triggered a wicked plot idea that could solve the physics / tech issues, meaning I would not have to violate anything but the protagonists trust!
 

Klystron

Gold Member
472
512
I no longer work designing or operating real weapon systems but fiction and history are another story. My idea of embedding the OP's 'bomb' inside the RF device is a play on WWII proximity fuze.

From 1940 we see a continuous-wave radar system with RF generated by a thyratron embedded in an explosive shell hardened for massive accelerations. Proximity devices were so effective they should have been developed for ground transport back in 20th C. if not for security classifications.

[Edit: added picture from 1940. This gadget looks deadly.]
1568241785763.png
 
Last edited:
1,333
691
Antimatter annihilation results in high-speed neutrinos and a burst of high-frequency gamma radiation, but not much of an 'explosion' it seems.
That's true only in space, with no matter around. In your case:
...the bomb is intended to go off in an underground base.
All the radiation (of any kind) will be absorbed by the ground, heating it up: so 100% will be converted to a definitely big bang.

By some random source from the web 20kt means ~ 1g matter (antimatter) converted to energy.
 
1,502
609
But, from various sources an antimatter bomb is not as destructive as the movies - and novels - suggest. Antimatter annihilation results in high-speed neutrinos and a burst of high-frequency gamma radiation, but not much of an 'explosion' it seems.
What the fuel turns into is not relevant. Nuclear bombs also release their energy largely in gamma rays. The point is all that energy ends up in the surrounding material, heating it up to millions of degrees, which causes it to expand. 99.99999999% of the damage caused by a nuclear weapon is done by the shockwave, not the flash.
 
217
88
[Edit: added picture from 1940. This gadget looks deadly.]
Yes it does :nb) (And I'm now on a tangent looking into these, just for fun.)

All the radiation (of any kind) will be absorbed by the ground, heating it up: so 100% will be converted to a definitely big bang.
and

99.99999999% of the damage caused by a nuclear weapon is done by the shockwave, not the flash.
Excellent, that's the missing conceptual piece for me. I need a massive bang - it's a big base! - and this addresses my original concern, thanks @Rive and @newjerseyrunner.
 
1,358
134
All the radiation (of any kind) will be absorbed by the ground, heating it up: so 100% will be converted to a definitely big bang.
Not any kind. Neutrinos don´ t participate in the bang.

The free path of pions in vacuum before they decay, in the range of 400 MeV energy, is around 10 m. So if you explode antimatter in a room filled with air a few m across, most pions that start off towards the airspace of the room cross the room and are absorbed in the opposite wall or ceiling. Minority of all pions decay in the room and waste part of their energy in neutrinos.

At a minimum, about 1/3 of annihilation energy goes via neutral pions to gammas which are absorbed and 1/6 of the rest goes to electrons/positrons. So absolute minimum 45 % energy into bang. Add energy from pions absorbed in nuclei where annihilation happens, muons that reach condensed matter before decaying... The energy that goes to bang starts from somewhere in 50...60 % if explosion is in midair and goes to maybe over 90 % in an enclosed room.

And even 50 % of 20 kT is a big bang. So is 90 % of 20 kT.
 
217
88
I've participated in a few posts in this forum and wondered what ever happened to the input, so I thought that if you're interested in how your collective feedback translated to my story, the antimatter discussion sequence is below. I've hidden the text in a 'spoiler' so if you're inclined to ever read the novel you don't need to have advance knowledge, though I also don't think it's a big reveal in the scheme of things, but either way, it's your choice...

“Tin, if we need to do this up close and personal, then we needed something more substantial than the ten of us with whatever guns we can carry. Let’s cut to the chase, how are we going to win this?”

Tin’s mouth curled down slightly, but he nodded. “Excellent question, Guardian. And I guess it might help you to know the end game. So…” He whistled and raised his eyebrows, then looked over us toward the kitchen. We turned to follow his gaze as a low-slung plonk entered the room. It looked like a millipede carrying an overlarge insulated water bottle tipped on its side.

“As I said before, the base is down deep and not even dropping nuclear bombs would do much damage in the time we’d have for that. So, we sneak in, we lay an egg, then we sneak back out before the egg hatches. It that up close and personal enough, Guardian?”

I shrugged and he gave us a cheeky smile. “Any thoughts on what the egg might be?”

I took it upon myself to talk my way through the options. “The water bottle is obviously the egg, but unless you’ve rewritten the laws of physics, Tin, it’s too small to be a nuclear bomb.”

I did not say it, but there just wasn’t enough fissile material there to set off a chain reaction and a dirty bomb would not damage Colossus, not unless up close and personal meant setting it off right next to Colossus and I wasn’t even sure that was possible.

“I’m not sure you can build a wormhole bomb, but if you’ve managed that the war would be irrelevant. You’d not be waiting here. You’d be opening wormholes all over the place, and nobody would be able to catch you out.”

Tin nodded, “That would indeed be amazing, Guardian, but the resources to open wormholes, no matter the size, is well beyond us.”

“Yeah, I figured. Then there’s only one other thing I can think of, and I am not even sure I want to be right. You’ve created an antimatter bomb, Tin.”

It was half a question, but Tin’s eyes lit up and I knew I was right. The mere thought was triggering informational alarms; even a tiny amount of antimatter was extremely dangerous and while it would pack enough punch to do serious damage to Colossus, it would do even more damage to us. I did not try and hide my concern.

“You don’t look happy, Guardian. Yes, it is antimatter, that was clever of you, but rest assured, it is well contained. Very well contained. I am not inclined to blow myself up any more than you would be, I’d guess.”

The others looked confused, but I ignored them. “Exactly how much antimatter is in that bomb, anyway?”

“Five grams.”

Five grams. About a heaped teaspoon of sugar, yet it would release enough energy to challenge most nukes. It was impressive as such things go, but the details bubbling up into my memories told me there was a problem.

“Tin, antimatter annihilation releases lots of gamma rays but not much in the way of an explosion. That base in New Zealand is extensive, so how is your egg going to do any real damage?”

“You need to brush up on your physics, Guardian. Each gram of antimatter releases about twenty kilotons of energy. It is mostly gamma rays, true, but they heat the surrounding area, creating a shock wave as the very bedrock the base is built into liquefies and then explodes from the pressure. But just in case that is not sufficiently destructive, they also provide the energy to fuse an outer layer of compressed tritium, which is guaranteed to make a bang. You are looking at what I am sure is the very first antimatter atomic bomb, a marvel of technology weighing a mere six kilograms.”

I wasn’t skeptical, not really, but it seemed overly complicated. “And you’ve tested this?”

“Of course. There is nothing casual about this, Guardian, all our lives depend on my device being stable for transport, and then going off as planned. I’ve spent years developing this, the bomb works, let’s just leave it at that,” he said, sounding peeved.

Once again, I was left wondering what he was leaving out. You don’t need a physics degree to know that antimatter is dangerous, so bringing it along as some kind of ultimate hand grenade seemed suicidal. Even a nanosecond glitch in the containment field would turn us all to radioactive waste, and Tin knew it. Something about his too smooth delivery rankled, but I couldn’t put my finger on it, so I merely shrugged.
 

Want to reply to this thread?

"Is an antimatter bomb feasible?" You must log in or register to reply here.

Related Threads for: Is an antimatter bomb feasible?

Replies
7
Views
344
Replies
11
Views
948
Replies
13
Views
5K
Replies
10
Views
1K
Replies
4
Views
587
Replies
24
Views
2K
  • Posted
Replies
4
Views
907

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top