back to article LHC records biggest bang ever with 1 Peta-electron-volt jolt

With the Large Hadron Collider's (LHC's) refit and restart accomplished, the records just keep tumbling. CERN has announced the highest-energy ion collision ever. The data generated by the experiment is going to take time and supercomputers to analyse, but CERN says the two lead ions slammed into each other at more than 1 Peta …

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Hot density rocks

From CERN article:

"There are many very dense and very hot questions to be addressed with the ion run..."

:-)

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Devil

Re: Hot density rocks

That sounds like a discussion of politics here in the States lately... "dense and hot".

Ok.. seriously question. Since they're generating "temperatures about a quarter of a million times those at the core of the sun.” and they want to go higher on the energy levels, how can they keep the temperature at the collision point from damaging the inside of the collider? I understand there's liquid hydrogen for cooling but even for a micro-second, that's a lot of energy to be dissipated.

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Re: Hot density rocks

Don't forget we're talking about two atoms.

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Re: Hot density rocks

It's energy density that wins the day, not energy overall.

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Re: Hot density rocks

We're talking pairs of atoms, not handfuls of the stuff, and probably not even nanoseconds of time.

Localised energy may be incredibly high, but it's localised to a very very tiny volume and lasts a very very short time.

The liquid helium cooling is so the superconducting magnets, well, you know... superconduct.

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Anonymous Coward

Re: Hot density rocks

"There are many very dense and very hot questions to be addressed with the ion run..."

Hopefully they'll have it in cannon form before the Star Destroyers arrive!

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Re: Hot density rocks

"how can they keep the temperature at the collision point from damaging the inside of the collider"

Note that 1 electron-volt equals 1.6x10^-19 joules. A single 1 peta-electron-volt (1x10^15 eV) blast amounts to about 1.6/10,000th of a Joule, and they're infrequent. If you manage to achieve 10,000 collisions per second, then the interior of the machine would have to deal with 1.6 Watts of heating. The massive vacuum casing and magnets probably won't notice 1.6 Watts.

However, the peta-volt collisions appear to be counted individually at this point, so you're probably not going to get full Watt-level heating.

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Re: Hot density rocks

Thanks for answering this. This stuff is way beyond me, but I find it fascinating and answers are not always readily available.

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Paris Hilton

@Mark 85 Re: Hot density rocks

You get down voted.

When you said Dense and Hot... trying to make fun of US politics, you should have used the Paris Icon.

(Subjectively dense and hot)

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Facepalm

Re: @Mark 85 Hot density rocks

My bad... I thought of doing two posts... probably should have.

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Coat

Re: Hot density rocks

Star Destroyers? Pfft, they are from a galaxy far far away.

I'm more concerned about those Vogons and their construction ships. They're local.

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Re: Hot density rocks

From what I've read of the LHC configuration [but please bear in mind, it's 30 years since I studied physics to A-Level], there are a couple of answers to your question...

Firstly, the "ring" that is used to accelerate the particles [well, OK, in fact it is actually 2 rings, one on top of the other, and with the contained particles traveling in opposite directions] is super-cooled in order to allow the magnets that contain the particles to get benefits from super-conductivity [i.e. to maximise field strength]. This means that when the particles are "just circling" they are not, in fact, colliding with anything at all, just zipping along through a vacuum...

Secondly, when the particles are allowed to collide - and the computers that govern the ring control whether or not this happens - the collisions can only occur at the location of the various experiments [ATLAS, CMS] that are positioned around the ring itself.

Now for the tricky part...

If you take two identical cars and set each to travel at 30mph until they meet in a head-on collision, the result of the impact is that both cars should [all things being equal] stop dead on the spot of the collision, because the respective kinetic energy each car brings to the collision would be exactly cancelled out by the other vehicle. The resultant energy is released as heat, [infra-red] light, and sound [and the gasps of insurance under-writers]. Point being that the two cars stop, or, if they do continue to move, it is at a fraction of their original speed and with a fraction of their original energy...

So now lets go back to ATLAS and CMS... Inside the huge chambers that house these experimental sensors, the environment is set up so that the high energy particles travel through the matter of the sensor, leaving a wake of interactions [with the sensor] as they go. Each interaction essentially robs a bit more energy from the particle, until it decays naturally [which is the way these particles behave, given their latent instability].

OK, we got as far as slow-moving particles... Because they are moving much more slowly now, and because their lifespan can be measured in millionths, billionths or even trillions of a second, they literally don't have time to travel beyond the physical confines of the detector before they literally disappear through decay.

So that's why the LHC doesn't melt itself...

I'll say it again: I'm not a physicist and I've only got a basic understanding from reading reports and articles from science journals and tech news sites like this one. Your mileage may vary [YMMV].

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Paris Hilton

Very dense and very hot?

See icon --->

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“At that temperature, matter becomes a strange thing called a quark-gluon plasma, not seen in nature since the universe's age was measured in microseconds.”

Is that true? I can’t believe that it took a human-made collider on Earth to achieve what was impossible for the last 14 billion years.

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Theoretically there are quark stars.

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Mushroom

Cosmic Rays

Ultra high energy cosmic rays can exceed this energy level. The "Oh-My-God particle" had an energy of approximately 3x10^20 electron volts. However the energy released in a single collision of such a particle with a stationary proton or neutron is much lower at about 7.5x10^14 electron volts. An (exceedingly unlikely) head on collision of 2 such such particles would release more energy than could be produced in any man made accelerator (even one as big as the planet!!).

(For more information on the Oh-My-God particle see https://en.wikipedia.org/wiki/Oh-My-God_particle)

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Re: Cosmic Rays

The "Oh my God" particle?

Whats the next one up from that going to be called? The "Jesus effing Christ" particle?

Or the "Oh shit we're F***** and going to die" particle?

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Coat

Technically, the "Oh shit we're F***** and going to die" particle exists. It's called a GRB and it comes in swarms (because more than one per burst).

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Re: Theoretically there are quark stars.

> The article you cite says that their existence has not been confirmed theoretically.

All right then, how about this:

Theoretically, there there are theoretically Quark stars.

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Re: Theoretically there are quark stars.

Hypothetically, there there are theoretically Quark stars.

FTFY

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At that temperature, perhaps someone can point Nigella to it to actually start cooking something more than just toast?

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Hey don't knock Nigella, we don't like Nigella knockers here.

Oh no, hang on...

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"Nigella knockers"

Photo please. Or else they never happened

Sounds like a novel ice cream with cherries on top

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> Photo please. Or else they never happened

Here you go.

* Pic is SFW for me cos I work at home; your workplace may vary :-)

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Nigella discussing her "plumptious beauties".

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Lead nuclear mass

I am a little bit confused about that. The nuclear mass of the common lead isotope is 208, so wouldn't it be 416 nucleons colliding?

At the energies involved, the two nuclei look to one another like thin discs colliding face on, so I imagine it is possible that some of the nucleons just go straight through and out the other side and the figure of 208 is coincidental, but it seems oddly specific to the lead nucleus mass.

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Re: Lead nuclear mass

It is indeed Lead-Lead collisions. More information here.

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Re: Lead nuclear mass - @tirk

"the Wikipedia article seems to suggest only protons are involved"

It's only the protons that are charged so it's those on which the accelerator works. The neutrons are just along for the ride.

A car analogy - it's only the tyre contact patch that touches the road so it's that that gets accelerated and the rest of the car is just along for the ride.

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Re: Lead nuclear mass - @Voyna i Mor

A nucleon is either a proton or a neutron, not a single lead nucleus. With an atomic weight of 208, a lead atom (or ion) has 208 nucleons.

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Re: Lead nuclear mass - @Voyna i Mor

atomic weight?

Atomic MASS

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This post has been deleted by its author

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Re: Lead nuclear mass - @Voyna i Mor

It does appear that the Wiki article neglects the presence of neutrons in the collision. Needs an edit.

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Re: Lead nuclear mass

Replying to myself, Chris Williams from the Reg has helpfully contacted me and as a result I now have the link to the CERN announcement.

Here

The announcement is a bit badly worded, I think. It explains that the total energy is about a PeV (1045TeV), and that there are 208 nucleons in a lead nucleus. It then suddenly switches to writing about nucleon pair energies, which are roughly 1045/208 or about 5TeV, without explaining that each nucleon of each pair is from each of the colliding nuclei. It's easy to miss that it is 5TeV per pair and not per nucleon. The point is that the total collision energy is the sum of the energies of each nucleus, so they are accelerated to a "mere" 522.5TeV each.

So yes, there are 416 nucleons involved and the energy per nucleon is about 2.5GeV as I surmised.

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Headmaster

@ x 7

atomic weight?

Atomic MASS

We can say either "atomic weight" or "relative atomic mass", but not just "atomic mass".

The terms "atomic weight" and "relative atomic mass" are exactly equivalent, both are still in common use, and both are still officially recognised by IUPAC.

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CURSES! Foiled again!

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Joke

Just ... mind-boggling

And I'm glad the involvement of Peta meant that no animals were harmed in the course of this experiment.

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Alert

Re: Just ... mind-boggling

Ah yes, but the barbeque afterwards.......

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Happy

Re: Just ... mind-boggling

Perhaps the electron volt should be renamed the Higg so that the LHC energy can be specified in petahiggs?

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Re: Just ... mind-boggling

Daddy Pig agrees with your sentiment.

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Re: Just ... mind-boggling

Those of us in PETA[0] NEVER harm animals. We raise them with tender loving care, then we kill them and eat them.

[0] That's "People Eating Tasty Animals", not the enviro-idiots "People Exterminating To Acquire"[1]

[1] Seriously, look up PETA's record on euthanizing all the strays that get dumped on them by completely clueless idiots[2].

[2] Don't get me wrong ... I'm no fan of "no kill" shelters ... but the PETA folks make a profit off of the concept. Frankly, it's quite disgusting.

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Re: Just ... mind-boggling

If members of PETA love animals, then whats their take on bestiality?

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Very dense and very hot?

I knew a girl like that once

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Re: Very dense and very hot?

... you knew Sarah Palin?

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Re: Very dense and very hot?

Sarah Palin wasn't hot - just sticky

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Coat

Re: Very dense and very hot?

You do realize that not only was she parodied on SNL, but also in a porn video.

MILF does a body good!

Mine is the jacket with the teflon coating so things don't get so sticky.

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Windows

Re: Very dense and very hot?

@ x 7

I do *NOT* want to know how you *cough* came by that information.

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