Antimatter atoms produced and trapped at CERN • Hacker News Board

Re: Antimatter atoms produced and trapped at CERN

#91

Post by juiceandjuice » Thu, Nov 18, 2010, 6:39 PM UTC

rubypay wrote: post #75

juiceandjuice wrote: post #67

Earlier quoted context omitted.

Only because the mass to energy conversion is 100%. But, if you factored in the size of whatever object you use to contain the antimatter, then your mass to energy conversion is probably comparable to a hydrogen bomb. Further, factor in the the energy required to contain the antimatter and it seems like it's losing proposition, probably until you start to approach the size of a small house or larger. So then the argu…

The "object you use to contain the antimatter" is not very large, it can be wheeled around in a lab. The "energy required to contain the antimatter" is not very significant, liquid helium cooled inside a liquid nitrogen shell, and some rather ordinary (in terms of power usage) electric and magnetic fields. 100 grams of antimatter has a yield similar to a 4 megaton hydrogen bomb.

But the question is what kind of infrastructure is needed to to contain 100 grams of positrons? There's no way you've contained 1/1000th of that amount otherwise you wouldn't be telling us about it on the internet (assuming you have Q/Top Secret clearance)

Also, assuming it is positrons, I'd imagine you might also have to worry slightly about relativistic background electrons and gamma rays/pair production, unless you're under 10ft+ of concrete. The extremely rare case that a 10^19 eV cosmic ray hits you head on sounds like an awesome way to possibly produce a spontaneous "detonation", or when some jokester thinks it's awesome to point a LINAC right at you.

Re: Antimatter atoms produced and trapped at CERN

#92

Post by fanf2 » Thu, Nov 18, 2010, 7:00 PM UTC

alex_c wrote: post #28

JoeAltmaier wrote: post #24

Earlier quoted context omitted.

They are neutral hydrogen atoms - why does a magnetic field affect them anyway?

The BBC article that's further down the front page at the moment brings it down closer to my level: http://www.bbc.co.uk/news/science-environment-11773791 ---- "Atoms are neutral - they have no net charge - but they have a little magnetic character," explained Jeff Hangst of Aarhus University in Denmark, one of the collaborators on the Alpha antihydrogen trapping project. "You can think of them as small compass needl…

Atomic clocks have the same problem. They use caesium atoms, which are hard to trap, and they want them moving very slowly so that thermal, doppler, and relativistic effects don't screw up the frequency signal you get from them. Hence caesium fountains, which fire the atoms upwards so that they come to the top of their gravitational parabola at about the time they drop a hyperfine energy level and emit the magic microwave photon.

Re: Antimatter atoms produced and trapped at CERN

#93

Post by InclinedPlane » Thu, Nov 18, 2010, 7:19 PM UTC

scorpion032 wrote: post #78

lutorm wrote: post #29

Earlier quoted context omitted.

Just based on what the article says, I suspect that even at the vacuum pressures they can achieve, there's enough normal matter around that eventually one of them penetrates the field and annihilates it.

Isn't the annihilation supposed to cause an explosion? How much energy is generated?

1 amu of anti-matter annihilates with 1 amu of matter and releases 0.3 nanoJoules of energy in the form of gamma rays. Or about 1.86 gigaelectronvolts (GeV, another unit of energy). In comparison, the particle collisions at the Large Hadron Collider occur at energies of about 14 TeV, or roughly 7,000 times more energetic, and occur numerous times per second.

Re: Antimatter atoms produced and trapped at CERN

#94

Post by InclinedPlane » Thu, Nov 18, 2010, 7:36 PM UTC

arethuza wrote: post #82

electromagnetic wrote: post #59

Earlier quoted context omitted.

Antimatter munitions scare me personally because they're a fail-deadly weapon. If the positron trap fails it goes kaboom. If a thermonuclear bomb fails in any way except a precisely calculated implosion you at worst you get a fissle, at best a guy in Whateveristan in the year 2040 gets his roof collapsed by a slightly radioactive dud. I hope, the only thing these are being designed for is some gamma-ray laser for a n…

I'm pretty sure I've read somewhere that if you did just dump a quantity of antimatter (e.g. by turning off the containment device) you wouldn't get a nice explosion - more a long drawn out messy fizzle. I would guess that a antimatter bomb would have to a similar design to fission or multi-stage devices where things are held together long enough by implosion for a significant proportion of the fuel to react.

I've done the math, you get an explosion quite rapidly. In a matter of nanoseconds the reaction of air in contact with the surface of the anti-matter chunk will release enough energy to vaporize the anti-matter and transform it into a growing ball of hot gas/plasma thoroughly mixed with matter, annihilation of the anti-matter completes in a matter of micro-seconds after that. This is if the anti-matter is just sitting in the open air, if it comes into direct contact with solid matter the process would probably proceed faster.

Re: Antimatter atoms produced and trapped at CERN

#95

Post by CamperBob » Fri, Nov 19, 2010, 4:11 AM UTC

juiceandjuice wrote: post #91

rubypay wrote: post #75

Earlier quoted context omitted.

The "object you use to contain the antimatter" is not very large, it can be wheeled around in a lab. The "energy required to contain the antimatter" is not very significant, liquid helium cooled inside a liquid nitrogen shell, and some rather ordinary (in terms of power usage) electric and magnetic fields. 100 grams of antimatter has a yield similar to a 4 megaton hydrogen bomb.

But the question is what kind of infrastructure is needed to to contain 100 grams of positrons? There's no way you've contained 1/1000th of that amount otherwise you wouldn't be telling us about it on the internet (assuming you have Q/Top Secret clearance) Also, assuming it is positrons, I'd imagine you might also have to worry slightly about relativistic background electrons and gamma rays/pair production, unless yo…

There's no way you've contained 1/1000th of that amount otherwise you wouldn't be telling us about it on the internet (assuming you have Q/Top Secret clearance)

If he has one now, he won't have it for much longer at this rate.