First successful beam at record energy of 6.5 TeV | Hacker News Reader

First successful beam at record energy of 6.5 TeV

home.web.cern.ch

158 pointsjonbaer67 comments

This is awesome!

I highly recommend 'Particle Fever', in case you haven't seen it yet. It cover's the LHC before the shutdown and restart, which included the Higgs boson discovery. Just fascinating look into what an international collaboration of human beings can accomplish.

IMDB: http://www.imdb.com/title/tt1385956/

Trailer: https://www.youtube.com/watch?v=Rikc7foqvRI

Netflix: http://www.netflix.com/WiMovie/70296323?trkid=13752289

The recent reviews at the Netflix link are priceless :)

Poe's Law has me at a loss.

Some highlights: mealy-mouthed malcontents

BIG-BANG-BELIEVING-BABBLERS

dead darkness drool that drips from the drooping face

Every fickle frame is filled with the foul stench of arrogant atheists

sad little men sit in the silent abyss of spiritual darkness wearing their dirty diapers of despair

dead-dogma doctrines

best movie ever, could use moar magnets

Though now as I go back through, some of the more ridiculous comments seem to be disappearing...

I need a t shirt with "sit in the silent abyss of darknes wearing their dirty diapers of despair"

Is there some meta joke i don't know, with all that alliteration.

Here's the dashboard updated in real-time if this sort of thing fascinates you (as it fascinates me!)

http://op-webtools.web.cern.ch/op-webtools/vistar/vistars.ph...

That is an interesting dashboard. On this page: http://op-webtools.web.cern.ch/op-webtools/vistar/vistars.ph...

all the changing numbers are actually dynamically generated PNG's...

So cool :D

That's pretty cool. Is there anywhere that explains what it all means?

Yes and no.

Yes: there's a link called "Doc" on the bottom of the page. This is the one for LHC Page 1, which is the most important display: http://op-webtools.web.cern.ch/op-webtools/vistar/Doc/LHC1.p...

No: well, you may only understand it if you have some background knowledge in some particle physics terms.

Would be cool if I could control it from this webpage ;)

Actually i think you can: (if you have rights to it ofc)

http://op-webtools.web.cern.ch/op-webtools/

Could someone explain the significance of this, for those of us that don't know?

I'm also a particle layman, this article seems informative of whats possible at 6.5 http://scroll.in/article/713144/What-will-we-find-next-insid...?

After the discovery of the higgs, CERN shut down the LHC and doubled its operating power.

For finer detail of discovery, we need more and more power in the accelerator.

The LHC just doubled it's power. While only operating at 50% it discovered several new particles including the Higgs Boson. Now that it's nearing 100% they're hoping to discover physics beyond the Standard Model. That could include things like additional spatial dimensions, Dark Matter, microscopic black holes and more.

TLDR: Hopefully opening the door for some mind blowing discoveries.

To expand upon what you're saying for the grandparent, what you have is one beam of protons can reach the kinetic energy of 6.5 TeV. They will circulate a second beam at the same energy, and collide them head on. Thus, the "center-of-momentum" energy, that is, the energy involved in a collision of one proton from one beam hitting another from the other beam will be 13 TeV at max. Often times, physicists refer to this energy by the symbol "s".

Basically, energy and mass are interchangeable in some violent reactions (like the ones at the LHC or that released in atomic explosions) as we know because of Einstein. This means that as we increase the energy of these violent collisions, the more energy that is available to be converted into the mass of possible particle products.

It should be noted that it isn't like we add mass to the products like adding snow to a snow ball, it isn't a continuum. It's more like a threshold. If a particle has a mass of 938 MeV, say, we will see it in a collision as a product only if s for that interaction is greater than 938 MeV. In fact, it must be a bit larger than this, because while some energy gets converted to mass, some energy also needs to get converted to energy of motion for these products too. Otherwise, they won't reach our the detectors in our apparatus for us even to see them.

We haven't seen a number of massive particles we think should exist, from a theory called "Supersymmetry". Note that we do not really know from theory what these masses should be, but we need them to exist for our current models of the universe. Our current guess then for why we don't see them is that we just haven't passed their threshold masses sufficiently to create them first and with enough energy after in order to see them.

That's why 6.5 TeV which implies a max s of 13 TeV is important. It's like we've increased the range of our "scan" of particle masses. It means we'll produce more massive particles (if they exist) and more of them in number with sufficient energy to actually see them.

This is a great explanation. One other bit I'll add is that the particles they're colliding are protons, which are made of other particles, called quarks. While the protons are colliding with a relative energy of 13TeV (or will be) the actual collision energy depends on the collision angle of the quarks inside the proton. If it's a glancing collision, which it almost always is, the actual collision energy is much lower. In other words, we don't get to make particles w/ masses of 13TeV. The Higgs for reference has a mass of 125 GeV. That's one reason physicist are considering using Muons in future accelerators instead of protons. They're not made of other stuff.

One of my favorite videos on this topic was a Great Courses video by Sean Carroll. Well worth the $40. http://www.thegreatcourses.com/courses/the-higgs-boson-and-b...

This is a very crucial point. Unfortunately, I cannot edit my post to point to it.

There's also a free mini-course by David Butler

https://www.youtube.com/playlist?list=PLpH1IDQEoE8Q8842yVe-V...

It goes into a little more detail than a typical popularizing course, but enough even for laypeople to understand.

David Butler also has a great introduction to astronomy in the same style:

https://www.youtube.com/playlist?list=PLpH1IDQEoE8QWWTnWG5cK...

I learned more from this comment than from my entire high school physics class.

> If a particle has a mass of 938 MeV, say, we will see it in a collision as a product only if s for that interaction is greater than 938 MeV

Just as a comment, we "only" saw the Higgs Boson (around 125GeV) at LHC energy levels, so the Higgs might get produced at small collision energies, but with a much lower probability

(I'm not disagreeing with you btw)

Microscopic black holes scares me. I once heard (entirely anecdotal - I'd love it if someone more knowledgeable on the subject could comment) they had calculated the probability that the LHC would create a black hole that consumed the Earth. The result was more likely than SHA1-hash collision, and was deemed safe enough to try. Somewhere between humorous and scary.

edit: did some Googling and found some documentation (https://en.wikipedia.org/wiki/Safety_of_high-energy_particle...). It cites an estimated upper limit of 1 in 50 million and references the book in which that estimate is made.

I can't see how this would be a problem even if a black hole was created.

A black hole is no different than any other massive object in that it doesn't exert any stronger pull than its mass allows for. In other words, if the Sun suddenly turned into a black hole right now, we would not get "sucked" into it. The Earth would continue orbiting at the same period and distance. Of course, it would suck (no pun intended) not to have sunlight but hey, maybe the energy emitted by the accretion disc would equal the energy output of the sun :P! Of course, an accretion disc would probably take a while to form, so we would probably be fucked anyway, but certainly not because we would be sucked into the black hole.

Similarly, if the LHC created a black hole through its collisions, I can't see how it would be that massive. If it's not very massive, then it's not a threat. In fact, there are theories that support the notion that it would evaporate rather quickly (via Hawking radiation). Of course, I don't have any numbers on this and only have a laymen's knowledge of the physics involved. Anyone care to comment with more info?

If it doesn't evaporate, it would (slowly at first) absorb the Earth. We might not get pulled in anytime soon, but it would sort of be a bummer for the future if the planet was destroyed in the next few thousand years.

(I don't think I have an interesting opinion when it comes to the question of whether such a hole would evaporate or not, but the question of why having a blackhole on the surface of the planet is bad is easier to think about)

Couldn't it be "contained" (it would break out eventually, as it would slowly suck in the container, but it could at least be contained for a period of time) and launched on a solar escape trajectory? Very, very expensive, but better than destroying the Earth in a few thousand years.

I guess it would pretty much be impossible to detect.

The article ufmace links in a sibling thread addresses the issue more directly, it wouldn't grow fast enough to be something to worry about, thousands of years is the wrong time scale.

To maxerickson:

I know what you mean, but I still think you have to look at the numbers. It seems plausible to me that the black hole might be so small that it would take literally millions of years or more to consume enough mass to become a threat. And that might even depend a lot on chance since most particles would just drift by it without passing inside of its event horizon since the force of gravity has very little effect at those scales.

Right, but if that were possible, it would have already happened. Cosmic rays hitting the Earth's upper atmosphere can already have much, much more energy than the LHC achieves. So the LHC is being ramped up to produce 13 TeV collisions... but we've measured cosmic ray impacts as high as 300,000,000 TeV. That was the so-called "oh my god particle", which had as much kinetic energy as a 60mph baseball, even though it was probably just a single proton. Sure, it's an outlier, but you can look at the overall distribution of cosmic ray flux:

http://en.wikipedia.org/wiki/Cosmic_ray#/media/File:Cosmic_r...

Let's move beyond "seems plausible" and try to work with "supported by the data".

Thank goodness 60mph+ baseballs don't annihilate matter when they impact baseball bats!

Indeed. The LHC collisions aren't special because they're particularly high-powered. They're special because they take place precisely in the center of an enormous particle detector. And have a precisely known energy level and composition.

Far higher energy stuff than anything we can dream of producing in a lab happens all over the world all the time. And the stuff that's documented now is only the things that have happened since we started being able to detect and measure it.

Here's a summary I posted a few days ago of an article I found explaining why it's absolutely impossible, not just unlikely, for the LHC to create a black hole that destroys the earth:

https://medium.com/starts-with-a-bang/could-the-lhc-make-an-...

TL:DR: 1.) If these miniature black holes exist, the Earth has been getting hit by them for billions of years, and it’s still here. 2.) If you do create a miniature black hole, they will decay, via Hawking Radiation, on ridiculously small timescales. 3.) You can compute the rate at which a black hole eats matter, and it’s not even close to being as small as the lifetime of our planet

>>Capturing 66,000 nucleons per second, how long will it take to get the black hole up to even one kilogram? Three trillion years

Thanks for the wonderful article.

A small question. Is this rate of consumption linear? Correct me if I'm wrong, the heavier the black hole gets, more and faster it can absorb matter. Of course given there is matter around it.

The article addresses that (It states that the growth will be linear until it reaches a certain mass).

I'm not a physicist or anything, but the idea I'm getting from that is that the event horizon of such a micro-black hole would be much smaller than a subatomic particle. It's too small to actually draw anything into it from a distance, so it would only be able to absorb something by running into it. The rate of consumption can't increase until the mass gets large enough to actually draw matter in from a greater distance than something like the size of an atomic nucleus.

The article author calculated how big that would be, and the black hole would reportedly need to accumulate about a billion tons of mass before it could start to grow exponentially.

The earth is constantly subjected to interactions at much higher energies than the LHC can produce. The LHC simply lets us concentrate a lot of reasonably energetic interactions in a small space.

Very small black holes are not stable. For all we know, they are being created all the time, but they evaporate almost immediately.

If it makes you feel any better, the Earth is hit by something like 4000 cosmic rays a day with energies that are 760,000 times higher than those being generated at CERN. That is 7 × 10^15 events since the Earth was formed and it's still here. :)

Sources and half-assed math: http://en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray

Lower limit for UHE cosmic ray: 10^19 eV

10^19 eV / 13 TeV = 769 230.769

24 events detected / 3 years in an area of 3,000 sq. km

Surface area of the Earth = 510 million sq. km

(510.1 million / 3000) * (27 / (3 years)) * 24 hours = 4188 events per day, or 7.19241 × 10^15 in 4.7 billion years.

Not happening.

Or rather, irrelevant if it does happen. You work out the mass loss via Hawking radiation, it's high enough at those mass levels that they'd just go "poof". The Earth isn't dense enough to sustain such a black hole.

Not to mention that if the LHC produced said micro black holes, they'd be produced by cosmic rays anyways.

This is going to be a bit abstract, but hopefully it still makes sense.

In particle physics there are a couple important fundamental principles, one of the most basic is the various conservation rules. Energy/mass, charge, lepton number, baryon number, etc, all of these things are conserved. But that leaves open a big window, because it means you can have any sort of particle reaction possible as long as you have enough energy and the various other "quantum numbers" (charge, leptons, whatever) are balanced. So, for example, if you have nothing more than high energy photons (gamma rays) you can create particle/anti-particle pairs easily (such as electrons/positrons) because in those situations everything that should be conserved is exactly balanced (since anti-particles have opposite charge, spin, lepton number, and so on). You can get more complex particle reactions so long as they are still balanced.

Now, let's say you want to study a particular particle. If those particles aren't naturally occurring, like protons or neutrons or electrons, then you'll need to figure out how to create them. And that means creating conditions where there's more energy available than the energy required for reactions that involve those particles. For example, the LHC was operating at 7 TeV total energy for collisions, which enabled them to discover the 125 GeV Higgs boson. Note that there's a significant difference in those energy levels (nearly a factor of 100), and this is because the process is somewhat inefficient and random and also there's some overhead in the reactions. For example, you need twice the energy of an electron particle in order to see electron-positron creation reactions, due to that balancing aspect.

Ultimately what you have is a huge collection of reactions due to particle collisions at a given energy level. And these reactions can be compared against the reactions you'd expect to see. With more energy in the collisions you push out the "search space" into different realms involving different particles and different phenomena. You can then use that data to perform "tests", by comparing what you actually see to what you'd expect to see given certain theories (such as the Higgs-mechanism theory), and in that way verify or falsify a theory. The more energy you have the easier it is to search for higher energy particles and phenomena.

The LHC energy boost will make it possible to explore new realms of physics. To either rule out the existence of potential particles at certain mass levels or to establish their existence, as with the Higgs-boson. It'll make it possible to narrow down some constraints on the Higgs-mechanism theory as well as potentially fill in some details (or rule out some possibilities) with regard to Dark Matter.

I recommend this infographic from Nature magazine; it explains the upgrades and what they hope to learn in this run (including about supersymmetry, dark matter, the Higgs boson and a B+ meson decay anomaly).

http://www.nature.com/polopoly_fs/1.17081!/menu/main/topColu...

And that's just one beam. There's a second beam, too - so they will crash into each other at 13 Tev.

Also, that's probably just a few bunches. (I'm guessing only one, but I may be wrong.) Every bunch contains ~10^11 protons.

When LHC is running in full, a total of 2808 bunches per beam are expected to be colliding there. That's a lot of energy.

http://hasthelargehadroncolliderdestroyedtheworldyet.com/

So the script checks if the variable worldHasEnded isn't defined to see if the world isn't destroyed. Hmm....

I guess that's a valid use for a global variable then.

https://www.youtube.com/v/tKdcjJoXeEY

Wasn't there an article on HN earlier this week about a 6.5 <some unit> pulse of energy being detected in space? It went on to suggest the possibility of intelligent life out in the universe. Maybe it was just some time warped echo from the LHC?

Weren't they aiming for 7 TeV?

As the training of the LHC magnets takes a long time, it was decided to run at 6.5 TeV per beam in 2015: http://home.web.cern.ch/about/engineering/restarting-lhc-why...

Maybe next year the energy will be increased to 7 TeV.

It was already running at 7 Tev, now it's at 13 TeV.

Currently it is at 6.5 Tev per beam. They will increase it to 7 Tev( which I was asking ) per beam.

It's so easy to be disappointed, isn't it? Fermilab had a .9TeV beam 30 years ago, so that's only ~7x in three decades, basically nothing for people accustomed to Moore's Law.

I will gladly accept mere incremental performance upgrades when my CPU speed crosses the ole terahertz barrier.

wooooooooooooooooo! congrats :) the screaming electrons live on. :) love that classic HMI screen. Just waiting to read the status line "Organics detected in reactor core." :) haha

What is that a reference to? Google links to here.

At first I wondered if it were this (Another World intro, 1991): https://www.youtube.com/watch?v=1j4gO9sR7zs

I think it's a game. It sounds familiar; I was going to ask the same thing!

:) Glad you like it. Yeah, "screaming electrons", "organics in the reactor" -- digital culture is awesome :)

Hahah, it reminded me of a part of the original half-life, I seem to remember that line popping out, even if the words weren't exact, the meaning was. "screaming electrons" connotes for me early BBS culture. Actually there was a BBS with 'screaming electrons' in its name.

That game looks priceless. I'll have to play it. Thanks for the video :)

How do they even create a 'beam of particles'?

Start with Hydrogen. Knock off an electron to get a proton which can be manipulated by electric and magnetic fields. Send them into the linear accelerator which has a series of electric plates to speed the protons up and focussing magnets to get the protons to line up nicely. Particles that don't form part of the beam are lost at low energy. Then the beams enter the ring accelerators for the big kick.

The coordination of the control signals is quite fun: it is capable of synchronizing events tens of kilometers apart to nanosecond accuracy.

Remember CRT's?

...or SLCs, "small lepton colliders" ;-)

So is that more or less than 1.21 gigawatts? ;)

I started some basic calculations in Google to find out what do you mean. So I converted 6.5 TeV to about 1 microjoule, then typed '1.21 GW / 1 uJ' to find out the beam intensity in particles/second, and realized that the first link is the Wikipedia entry for 'DeLorean time machine'.

(And the answer is that it's more than 1.21GW so long as they're sending 1.2x10^15 of them every second.)

Hoverboards don't work over water, McFly!

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