
Antimatter experiment produces first beam of antihydrogen - hiby007
http://home.web.cern.ch/about/updates/2014/01/antimatter-experiment-produces-first-beam-antihydrogen
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TrainedMonkey
High energy physics is one of the leading fields that drives scientific
progress forward. Studying antimatter is particularly cool, because at the
face value it is one of the most efficient ways to store energy (Basically
100% of matter gets converted to energy). Now if only we could figure out a
way to cheaply produce it without relying on fossil fuels.

~~~
Florin_Andrei
> _Studying antimatter is particularly cool, because at the face value it is
> one of the most efficient ways to store energy (Basically 100% of matter
> gets converted to energy)._

In theory, a black hole is also a 100%-efficient converter of matter into
energy, via the Hawking radiation. A microscopic BH might radiate very large
amounts of Hawking radiation. The bonus is that, unlike antimatter, you can
make (or at least fatten up) a BH directly from ordinary matter, without
spending energy as a prior step (anti-matter is energy storage, a black hole
is an energy source - if you're willing to spend some dirt as "fuel").

Of course, the problem of storage is just as bad, if not worse.

~~~
wyager
I hadn't thought about black holes as an energy source. Cool idea. But where
does the energy actually "come from"? With M/AM interactions, the M/AM is
annihilated, which creates harvestable photons. Does the energy given off by a
black hole come from the change in entropy from structured matter to
unstructured Hawking radiation or something? It seems almost too easy if we
can just feed any old matter into a black hole and get energy out...

~~~
waps
The energy comes from virtual particles. You should think of it this way :
anything has a certain chance of happening, but must follow conservation laws.
Conservation of energy, conservation of mass, conservation of ... (the "real"
conservation laws are more complex, but ... E.g. only mass+energy+entropy is
constant, not mass, nor energy, nor entropy). But small, "short term"
violations are possible.

Now imagine there are particle pairs that, when added together have zero mass,
zero energy, zero ... These would pop into existence in pairs everywhere and
be anihilated soon after. Same is true for triples, quadruplets, ... with
different probabilities. Surprise : these particles "exist" (normally for very
short times).

So particle a and particle b come into existence, both particles on a path
that separates them from eachother. However, because opposite charges attract
(and other effects related to other forces) they will fall back into eachother
after a while, anihilating eachother and leaving nothing. These are generally
referred to as "virtual" particles.

Except of course if something comes between them while flying on their path.
This results in multiple effects, like the Casimir pressure, and hawking
radiation.

The Casimir pressure is simpler. Suppose you have 2 straight plates, and you
bring them close together. So close that these virtual particles have a good
chance of impacting one but not the other. If the plates are metal, the
particles will generally "merge" with it (like electrons). So a tiny
percentage of the virtual particles between the plates become real.

This does not affect virtual particles that are not between the plates. So
there is a clear differential between vacuum interactions outside of the
plates and inside. This results in a massive pressure pushing the plates
together, like removing gas particles in a container results in a pressure on
the outside of the container (and, in an athmosphere of large molecules, if
you move plates closer together than the size of the gas molecules, there will
be a pressure that pushes the plates completely together).

Likewise, in black holes what comes between the particles is an event horizon.
Event horizons "erase" quantum information, only the black hole as a whole has
quantum information (the reason for is that black holes are physical,
localized, manifestations of the end of time : they don't have an inside as
far as anything outside the black hole can detect), no individual parts of a
black hole have quantum state. So if an electron crosses the event horizon the
charge of the entire black hole changes instantaneously, and the point charge
of the electron disappears. That means the charge pulling the particles back
together (assuming an e+ and e- virtual particle pair) becomes much more
distant to the particle, and if it has enough speed and a convenient direction
it will fly away from the black hole. Due to conservation laws the net result
is that the black hole has eaten a somehow negative-mass charged particle, and
the mass has decreased. A particle has been created outside of the black hole
and is flying away to infinity.

The vast majority of these particles are photons of a specific frequency, and,
surprisingly, the smaller the black hole, the larger the effect (and the
higher the frequencies). So spaceships would have to carry "heavy" black holes
to get a decent output and would have to "feed" the black holes to avoid
exploding (millions of tonnes as least, and you have to shovel in matter at a
rate of 10+ kg per second to keep it stable. Or you could reflect hawking
radiation back in). And of course, large black holes have large inertia (plus
: how do you hold on to one ? Electrical fields can do it, but it would have
to be a field so huge it baffles the imagination ...).

A 1kg black hole would be converted into energy in less than a planck second
by this effect and there is nothing, even theoretically, that can hold back
that energy. Such an explosion might even do what people were "afraid" would
happen with CERN's Higgs experiments and disrupt the Higgs field, causing a
cascading conversion of the energy "powering" inertia into photons (the higgs
field is something like a magnetic field that opposes all velocity changes in
mass). If this were to happen, it would look one hell of a lot like a big
bang.

~~~
tempestn
Is there a similarly simplified explanation for why the black hole tends to
'eat' the negative-mass halves of the virtual particle pairs but not the (or
at least more often than the) positive-mass ones? Just going by your
explanation above, it seems just as likely that the positive-mass particle
would be captured by the black hole, emitting the negative mass one, but since
the black hole loses mass through this radiation, that must not be the case.

~~~
grkvlt
They're not 'negative mass' particles, they are anti-particles, which have the
same (positive) mass as the normal particle, but opposite charge.

~~~
xerophtye
well by his definition they HAVE to be negative mass. Because when these
particles unite, they end up having ZERO mass, energy, entropy etc. So all of
their properties must be inverses of each other, including mass

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ChuckMcM
The lack of antimatter is an enduring mystery. And creating it is always cool.
And I find it particularly fun to imagine anti-matter fusion plants producing
anti-helium (more bang for your buck antimatter :-).

~~~
HCIdivision17
It thrills me that the Antiproton Decelerator is a legitimate thing that is at
least as cool as it sounds. The need to slow particles down is obvious only in
retrospect for me,which I'm a little ashamed to admit.

Add, too, that the acronyms are excellent.

[0]
[http://en.wikipedia.org/wiki/Antiproton_Decelerator](http://en.wikipedia.org/wiki/Antiproton_Decelerator)

------
Create
"How should we make it attractive for them [young people] to spend 5,6,7 years
in our field, be satisfied, learn about excitement, but finally be qualified
to find other possibilities?" \-- H. Schopper

The numbers make the problem clear. In 2007, the year before CERN first
powered up the LHC, the lab produced 142 master's and Ph.D. theses, according
to the lab's document server. Last year it produced 327. (Fermilab chipped in
54.) That abundance seems unlikely to vanish anytime soon, as last year ATLAS
had 1000 grad students and CMS had 900.

In contrast, the INSPIRE Web site, a database for particle physics, currently
lists 124 postdocs worldwide in experimental high-energy physics, the sort of
work LHC grads have trained for.

Let's not confuse students and fellows with missing staff. [...] Potential
missing staff in some areas is a separate issue, and educational programmes
are not designed to make up for it. On-the-job learning and training are not
separated but dynamically linked together, benefiting to both parties. In my
three years of operation, I have unfortunately witnessed cases where CERN
duties and educational training became contradictory and even conflicting.

[http://ombuds.web.cern.ch/blog/2013/06/lets-not-confuse-
stud...](http://ombuds.web.cern.ch/blog/2013/06/lets-not-confuse-students-and-
fellows-missing-staff)

An unsatisfactory contract policy

This will be difficult for LD staff to cope with. Indeed, even while giving
complete satisfaction, they have no forward vision about the possibility of
pursuing a career

[http://staff-
association.web.cern.ch/content/unsatisfactory-...](http://staff-
association.web.cern.ch/content/unsatisfactory-contract-policy)

Pensions which will be applicable to new recruits as of 1 January 2012; the
Management and CERN Council adopted without any concertation and decided in
June 2011 to adopt very unfavourable mesures for new recruits.

[http://www.gac-
epa.org/History/Bulletins/42-2012-04/Bulletin...](http://www.gac-
epa.org/History/Bulletins/42-2012-04/Bulletin42-en.html)

And a warning to non-western members:

"The cost [...] has been evaluated, taking into account realistic labor prices
in different countries. The total cost is X (with a western equivalent value
of Y) [where Y>X]

source: LHCb calorimeters : Technical Design Report

ISBN: 9290831693 cdsweb.cern.ch/record/494264

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sytelus
Here's two cool thing about this experiment: Normal Hydrogen atoms do respond
to magnetic field feebly. They feel repulsion while travelling in a field
gradient. Anti hydrogen has same property and that's how you keep it away from
normal matter.

Second, they were able to produce 25 anti-Hydrogen atoms per hour. They
measured total 80 of those. A long way from anti-matter weapons :).

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jxf
Can someone explain where the antihydrogen winds up after being created? Is it
annihilating with something?

~~~
InclinedPlane
Even extremely strong vacuums contain large amounts of atoms, and there are
the walls of the vacuum chamber, of course. When an anti-hydrogen atom
collides with any normal atom an electron will annihilate with the anti-
hydrogen's positron leaving behind a negatively charged anti-proton which will
fairly rapidly collide with a positively charged proton in a nucleus.

~~~
jxf
Wouldn't colliding with the walls of the chamber be extremely undesirable?
That seems like it would create stress/damage in the chamber, and given how
sensitive and expensive ALPHA is I'd imagine that they don't want to do that,
right?

~~~
Sharlin
We must remember we're talking about a few _dozens_ of antiatoms here. The few
gamma photons they turn into when annihilating are so utterly insignificant
compared to natural background radiation it isn't even funny.

~~~
InclinedPlane
Not to "actually" here, but actually... while positron/electron annihilation
results in just photons most of the time the situation with anti-proton/proton
annihilation is much more complex. Initially you end up with a bunch of high
energy pi-mesons (you can think about this as the quarks and anti-quarks
pairing off, which isn't really correct since typically more than just 3 pi-
mesons result from an annihilation, the typical number is about twice that).
These then decay into showers of other particles. Photons, certainly, but also
leptons/anti-leptons (muons and electrons) and neutrinos.

In terms of intensity you are absolutely correct though.

~~~
Sharlin
Thanks, yeah, for some reason I just considered the electron/positron case :)

