Is CERN LHC suppose to create matter or simply analyse debris of collision ?

[azoulay]

I read 2 books on CERN's LHC and I'm confused by the different information provided in regards to what exactly will the detectors will be analyzing.

In the first book ("Present at creation" author: Mr.Aczel), it is clearly written that after the beams collides, matter (protons) will be transformed in pure energy and that energy will transformed itself into matter and this new matter "may constitute particles like those that existed when the universe was only a tiny fraction of a second old" So it seems that the LHC will be analyzing this new matter that just formed out of the collision.

In the other book ("Collider" author: Paul Halpren). It never says anything about new matter being created. It simply mentions that they will be analyzing the debris of the collision of the proton beams.

Well now I'm confused. Is it new matter that they will be analyzing or debris (that flies off in all direction) due to the collision?

Regards,

Jonathan

 

[TriTertButoxy]

The debris of the collision is the new matter that was transformed back from pure energy.

i.e. the matter created from the collision is the debris.

 

[azoulay]

Isn't strange that the author never mentions the new matter being created and only refers to the debris of the collisions?

 

[ZapperZ]

Please note that this is nothing new. High energy physics experiments have been doing this all along (LEP, ZEUS, KEK, BELLE, Tevatron, BaBAR, etc.).

Zz.

 

[Bill_K]

Isn't strange that the author never mentions the new matter being created and only refers to the debris of the collisions?

Both statements are correct. They will be 'creating new matter' and 'analyzing the debris.' The new matter that is (hopefully) created will be too short-lived to be directly seeable. All they can do is analyze the debris resulting from the decay of this new matter, which will consist of plain old pions, muons, etc

 

[azoulay]

Please note that this is nothing new. High energy physics experiments have been doing this all along (LEP, ZEUS, KEK, BELLE, Tevatron, BaBAR, etc.).

What exactly do you mean when you mention that "this is nothing new" what is it that's not new?

Regards,

Jonathan

 

[ZapperZ]

What exactly do you mean when you mention that "this is nothing new" what is it that's not new?

Regards,

Jonathan

That particles are created via such high-energy collisions. CERN/LHC isn't the first place that this is occurring.

Zz.

 

[azoulay]

When these collisions occur, is it 100% of all the protons that are transformed in energy and re-transformed in new matter or is there actually some debris (from the "old" matter) that is also analyzed?

Regards,

Jonathan

 

[James50]

You can't break a proton up into its constituent components (quarks) like you are suggesting due to colour confinement of the quarks. Remember, energy and matter are very easily converted, so the concept of debris made of the 'old' matter isn't valid. It is like colliding two cars together, but instead of getting engines, prop shafts and chairs flying everywhere, you have vacuum cleaners, fridges and footballs flying everywere. There is a relation between what was collided and the products, but it can be quite complicated and very analysis-heavy, which is why you have a great many computers attached to the detectors.

 

[azoulay]

Thank you for the explanations, it's very interesting stuff but it's also counter intuitive.

What I understand is that while the collision of the 2 proton beams is taking place, the transformation of the protons in pure energy is instantaneous. And this pure energy also instantaneously transforms into new matter that is too short-lived to be directly observable. So it's the decay residue of this non-observable too short live matter that is analyzed. And from this analysis, we try to figure out what exactly was this matter that we didn't get to see because it was too short lived. Did I get it right?

Does that mean that we need to know in advance what this (too short-lived) matter has to decay into to be able to figure it out the other way around? Are I'm I missing something?

If so, how do they know what this (too short-lived) matter is suppose to decay into if they never "encountered" this (too short-lived) matter before?

Regards,

Jonathan

 

[James50]

Your first paragraph is pretty sound, although the concept of 'pure energy' you are talking about is perhaps a little misguided - things (photons, matter, exchange bosons etc) can have energy, but can't really be described as pure energy. Energy is rather a measure of some quantity; although what that quantity exactly is should be a question for philosphers rather than particle physicists!

You don't necessarily have to know what it decays into. As this 'unseen' particle decays, it will generally decay into a certain pattern of particles and masses. These particles can be analysed and there will be a peak number of decays at a certain mass. This mass is known as a 'resonance' and is directly attributable to the 'unseen' particle.

However, with the Higgs in particular, it is already known what its mass is limited to thanks to the LEP which set a lower limit, and the upper limit set by the non-appearance of virtual Higgs loops in the W boson. Knowing what something will decay into is just based on various conservation laws, coupling terms and what is kinematically allowed. The LHC is expected to collide protons which will then form top quark loops and decay into the Higgs. The Higgs will then decay into bottom-quarks or W bosons, and then off into masses of hadron jets! The analysis of these hadron jets is very CPU heavy, and will take some time (a few years, at least!).

 

[azoulay]

thanks again !

 

[kloptok]

...

What I understand is that while the collision of the 2 proton beams is taking place, the transformation of the protons in pure energy is instantaneous. And this pure energy also instantaneously transforms into new matter that is too short-lived to be directly observable. So it's the decay residue of this non-observable too short live matter that is analyzed. And from this analysis, we try to figure out what exactly was this matter that we didn't get to see because it was too short lived. Did I get it right?

...

When the protons are accelerated they gain kinetic energy. So to clarify, the protons carry a lot of energy when they are accelerated to such high energies (basically only kinetic energy). This energy can then be used (remember E=mc²) to create new matter when the protons collide. The created particles then decay in some specific way into lots of other things and this makes it possible to retrace the steps when analysing what came out of the collision.

When these collisions occur, is it 100% of all the protons that are transformed in energy and re-transformed in new matter or is there actually some debris (from the "old" matter) that is also analyzed?

Regards,

Jonathan

When colliding two protons there are a lot of things happening except for the process resulting in the particle you want to find. What collides is actually gluons or quarks from inside the protons, with different probabilities (and different amounts of energy) depending on the constituent particle that collides. Except for this so called "hard process" there are lots of other things going on, such as stuff coming from the remnants of the protons for example. There can also be multiple collisions between constituents of the protons. All of this makes it quite complicated to analyse the results of hadron (a hadron is a composite particle made of quarks) collisions, as compared to lepton collisions, where the colliding particles are pointlike.

 

[azoulay]

Except for this so called "hard process" there are lots of other things going on, such as stuff coming from the remnants of the protons for example.

So it seems that there is actually remnants (debris of the "old matter") after the collision ?

How can they differentiate these remnants from the new matter that just has been created? Is there a way to differentiate between the two?

Regards,
Jonathan

 

[Drakkith]

So it seems that there is actually remnants (debris of the "old matter") after the collision ?

How can they differentiate these remnants from the new matter that just has been created? Is there a way to differentiate between the two?

Regards,
Jonathan

When particles are collided together at such a high velocity that they begin to "break apart" and such, they aren't actually breaking apart and there isn't any "remnants" really.

For example, when you collide a proton with another proton, the quarks inside have a tremendous amount of energy pushing them around due to the collision. The strong force, which holds quarks together into protons and other particles, does NOT get weaker with increased range. As a quark moves away from another quark the energy it takes to move it further increases. After a certain point it is more favorable to create NEW particles instead of moving the quarks further apart. So new quarks are created of various types which bind with the old quarks AND with new ones and all these form new particles.

There are no "remnants" in the sense that there are no leftover pieces. All the mass and energy is converted into new mass in the form of particles or in the resulting kinetic energy of the new matter. The amount of NEW matter created can have more mass than the original particles that collided. The extra mass comes from the energy used to accelerate the protons to their collision speeds.

And by new matter I mean particles that are created that were not there before the collision. They are looking for particles that are new in the sense that they have never been observed before.

As was said above, they have to do massive amounts of collisions and calculations to sort out all the different particles created and see if any meet the criteria of "new".