2.1 - The Particle Zoo Flashcards
What happens when a cosmic ray enters the earths atmosphere
They create new short lived particles and antiparticles as well as photons
Process of how cosmic rays create new short lived particles
Cosmic rays are fast moving protons or small nuclei. When they collide with gas atoms in the atmosphere they create showers of particles and antiparticles that can be detected at ground level by cloud chambers
What new types of short lived particles and anti particles were discovered using the cloud chamber
The muon - (heavy electron)
The pion
The kaon
Facts about the muon
Heavy electron
Symbol (u)
Negatively charged particle with a rest mass of over 200 times the electron
Facts about the pion or pi meson
Can be negative, positive or neutral
Has a rest mass greater than a muon but less than a proton
Facts about the kaon
K meson
Can be positive negative or neutral
Has a rest mass greater than a pion but less than a proton
how are kaons produced
In twos through strong interaction
-when protons moving at high speeds crash into nuclei and they each travel far beyond the nucleus which they originate from before they decay.
Why must kaons decay via the weak interaction
the decay of kaons took longer than expected and includes pions as the product
this is why kaons are called strange particle
How can all the new particles be created
using accelerators in which protons collide head on with other protons at high speed
What happens to the protons when they collide
the kinetic energy of the protons is converted into mass in the creation of these new particles
so these new particles can be studied under controlled conditions
Kaon decay mode
A kaon can decay into Pions, or a muon and an antineutrino or an antimuon and a neutrino
Charged pion decay mode
A charged pion can decay into a muon and an antineutrino or an antimuon and a neutrino
A pi 0 meson decays into
high energy photons
Muon decay mode
A muon decays into an electron and an antineutrino
An antimuon decays into
A positron and a neutrino
what must decays always obey
the conservation rules for energy, momentum and charge
what is a tv tube in a traditional tv
an accelerator because it accelerates electrons inside it through a potential difference of about 5000V
how is the image produced on a traditional tv
the electrons form a beam that hits the inside of the tv screen
magnetic fields produced by electromagnets deflect the beam so it scans the screen to create an image
what is the longest accelerator in the world
stanford linear accelerator in California
distance of3km and pd of 50000million volts = 50Gev
what is the biggest acellorator in the world
large hadron collider at CERN near Geneva
accelerates particles to energies of more than 7000 GeV
27km circumference
what did Hideki Yukawa predict before the discovery of muons kaons and pions?
the existence of exchange particles for the strong nuclear force between nucleons
thought they would have a range of no more than 10^-15 and calculated that there mass would be between the electron and the proton
Called them mesons because they were inbetween
what did Carl Anderson obtain a photo of in his cloud chamber
could have been produced by a meson but it had a track length of 40mm so lasted longer than a strongly interacting particle should
proved to be heavy electron later called muon
decays through weak interaction
when was Yukawa’s meson discovered
years later by British Physicist Cecil Powell from tiny microscopic tracks found in photographic emulsion exposed to cosmic rays atvs high altitude
Powell called them Pi mesons /pions
