How is antimatter stored in the large hadron collider?

Question

we studied that antimatter can be stored in the large hadron collider. what i dont get is that the collider is used to collide particles and antiparticles together right? so how is antimatter stored in the collider without it interacting with the accelerating matter and causing pair production? also in our book its written that the particles are accelerated to such high speeds to increase their mass. why would you need to increase mass if you're simply colliding two types of particles?

Answer 1

First of all LHC is not colliding antimatter... it's a proton-proton collider... so no antimatter. But the problem is not colliding anti-particles... In other accelerators particles and anti-particles are kept in a vacuum pipe by means of strong magnetic fields (to bend the particles along the expected trajectory) so there is no interaction with the matter but when the particles collide.

For what concern the mass... it's not that someone is increasing the mass of the particles... it's just a common effect which is true for all matter... it's true also for very low speed but it's hard to measure it... but for particles with very high speed (near the light speed) the effect is important. All is explained within the special relativity theory by Einstein.

Answer 2

Antimatter is not stored in the Large Hadron Collider (LHC). The LHC collides matter with matter, of various types. Namely, proton-proton, proton-lead, lead-lead, and xenon-xenon collisions have all happened in the LHC; none of those involve antimatter.

There are other places at CERN (the laboratory where the LHC is located) that do store antimatter. Various antimatter experiments, such as ALPHA, ASACUSA, ATRAP, and BASE study the properties of antimatter, and they get their antimatter from the Antiproton Decelerator (AD). If you want to store antimatter, you have to have some way of preventing it from annihilating on the walls of your container. The easiest way to do this is to use magnetic fields to keep the antimatter moving in a ring, where the fields have been precisely designed to minimize the possibility of collision with the walls. The antimatter is also slowed down in the ring ("cooled") by strong electric fields, so that anti-atoms can be constructed for the various experiments.

There are also other colliders that do collide matter and antimatter. For example, the Tevatron, formerly at Fermilab, collided protons and antiprotons. The antiprotons were created and immediately injected into the collider ring. Any leftover antiprotons were dumped into an absorber, where they annihilated.

As for your other question, the masses of fundamental particles are fixed, and do not change with energy.

Answer 3

we studied that antimatter can be stored in the large hadron collider.

As Attilio says the large hadron collider now collides protons on protons.

In the same tunnel there used to be the LEP collider, where electrons fell on the positrons in specially designed interaction points, otherwise they were separate beams in the same beam pipe.

what i dont get is that the collider is used to collide particles and antiparticles together right?

The LEP yes,

so how is antimatter stored in the collider without it interacting with the accelerating matter

magnetic fields can and do control beams in vacuum perfectly.

and causing pair production?

Only when brought together on purpose in the experimental halls so as to study the production after the annihilation, as experiments at LEP did.

also in our book its written that the particles are accelerated to such high speeds to increase their mass. why would you need to increase mass if you're simply colliding two types of particles?

It is using a special relativity concept which is no longer used, there is a relativistic mass that increases the higher the velocity of a particle or antiparticle, but it is a concept no longer used in particle physics. One uses relativity four vectors which describe the interactions of elementary particles simply. The energy and momentum fourvector has as a length the invariant mass of the particles (or antiparticles, or system of particles) which , as its name says, is a unique characteristic of the particle (or system) as seen in this table.

What you need to do to study elementary particle interactions is increase the center of mass energy of the two bodies scattering. The more energy the more channels open for the study. Because of the relation of invariant mass with energy and momentum

the larger the invariant mass (addition of their four vectors) of the two particles that are colliding, the more energy in the center of mass, and this allows the production of heavier pairs. The "increase in relativistic mass" of your book just confuses this simple picture although mathematically it is equivalent.