What happens when protons are absorbed by a nucleus?
The atomic number is increased and a new element is formed.
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What does a proton need to be absorbed by a nucleus?
It needs lots of energy, so the process takes place in a cyclotron
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What are the radioactive isotopes made by proton enrichment?
They are usually positron emitters.
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What is a positron?
It is an antiparticle of an electron - it has the same mass but an opposite charge.
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What are particle accelerators used for?
We can smash particles together at very high speeds to see what happens which can give us clues on how the world works, expertise is combined as it happens internationally.
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What is CERN?
It is the European Organisation for Nuclear Research
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Why are CERN important?
They built a collider in Geneva which is the largest and most powerful ever built. They are trying to recreate the conditions from just after the Big Bang.
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What is an elastic collision?
Momentum is conserved and kinetic energy is conserved.
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What is an inelastic collision?
Some kinetic energy is converted into other forms of energy during the collision and momentum is conserved.
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What happens to momentum in any collision or explosion?
Momentum is always conserved.
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What is annihilation?
When a particle meets its antiparticle, annihilation happens - the mass of both particles are converted into energy which is given off as gamma rays.
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What happens when electrons and positrons meet?
They collide head on with each other at the same speed but moving in opposite directions. They have the same mass but opposite velocities.
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What is the momentum before the collision?
The momentum before the collision is 0
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What is the momentum after the collision?
Momentum is always conserved so the gamma rays must have a total momentum of 0
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The gamma rays produced have...
the same energy but opposite velocities.
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What happens to charge in particle reactions?
The charge before the reaction equals the charge after the reaction.
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The charge before electron/positron collision and also after it is..
0 as gamma rays have no charge.
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What is mass energy?
Mass can be converted into other forms of energy so it is easy to say that mass and energy are the same.
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In annihilation, mass energy is...
conserved.
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What happens to the mass of the positron and electron?
The mass is converted into energy.
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What happens in PET scans?
In PET scans a positron emitting radioactive isotope is injected into a patient. The positrons collide with the patients electrons and annihilate to produce gamma rays.
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Where is there a higher take up of the radioactive isotope?
In cancerous cells, so detectors detect pairs of gamma rays and when three pairs are found, triangulation is used to detect the cancer.
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Other cards in this set
Card 2
Front
What happens when protons are absorbed by a nucleus?
Back
The atomic number is increased and a new element is formed.
Card 3
Front
What does a proton need to be absorbed by a nucleus?
Back
Card 4
Front
What are the radioactive isotopes made by proton enrichment?
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