LHC about to restart - some frequently asked questions

[mheslep]

Hyperphysics - HTS
Wiki HTS
https://www.physicsforums.com/search/603685/?q=high+temperature+superconductors&o=relevance

 

[Vanadium 50]

6.5 TeV pilot bunches have circulated in both directions.

 

[Vanadium 50]

Experiments are seeing beam-gas collisions.

 

[mheslep]

Experiments are seeing beam-gas collisions.

Meaning beam - neutral collisions?

 

[mfb]

Collisions with remaining gas (mainly hydrogen) in the beam pipe. Those collisions are highly asymmetric and of low energy as they are basically fixed-target experiments.
Still useful to see if the detectors are working properly.

 

[bipin sonawane]

In this run of LHC ( 2015) , are we doing the investigation of spin and other related parameters of "the proton"?

 

[mfb]

No, the LHC experiments are not sensitive to properties of the proton as hadron - they see its components (quarks and gluons) only, those get studied.
Other experiments at much lower energy are used to study protons as effective particles.

 

[bipin sonawane]

Thanks mfb .
As per the theory is concerned the spin of the proton is the sum of the spins and angular momenta of its constituent particles that is quarks and gluon.But it is known that this sum is not equivalent to 1/2 ,which is the spin of the proton,something which contribute in the spin of the proton is missing. My question is - in this LHC run will we compute the spins of quarks and gluon? Do we collide polarized and unpolarized protons ?

 

[mfb]

The proton beams are unpolarized - it is not relevant for the main physics goals and polarizing them to a reasonable degree would be additional effort. I would guess that HERA data is much better even if the LHC had polarized protons.

 

[mfb]

Part 2 is there! To focus discussions to one thread, I closed this one.