7C.4 Particle Reactions Flashcards
what is conserved in particle reactions
- energy/mass
- momentum
- charge
- lepton numbers
- baryon number
why is it hard to check of energy and momentum have been conserved in particle reactions
in a reaction, the particles can can begin or end with more kinetic energy out balance out the mass difference. for example how some collision experiments would convert particles with high Ke to more particles or heavier particles with a lower Ke, and the same can apply to momentum
what is an alpha particle decay
the radioactive process in which a particle combination of 2 protons and two neutrons is released from the nucleus
what is the beta-minus decay
the radioactive process to which a nuclear neutron changes to a proton, and an electron is ejected from the nucleus
what is the alpha and beta decay equation
108
why is the anti-electron neutrino in beta-minus decay
because the beta particles of the same isotope has a range of kinetic energy, but energy is supposed to be conserved like inn alpha where it has one kinetic energy, so they figured out there was another particle that was flying away, also to have equal lepton number
in beta decay we can have two beta particles which are
either beta + or beta -
what is a baryon number
the quantum number for barons where as proton has B=1 for anti baryon B = -1
each quark has a baryon number of
+1/3 and for anti - 1/3
what is the lepton number
the quantum number of leptons L= 1 for anti leptons L = -1
mesons baryon number is
0 since its made from a quark and a anti quark
what is strangeness
a quantum number for strange quarks where S=-1 and anti S = +1
strangeness is conserved in
strong and electromagnetic forces
Einstein claimed that for fast moving electrons time
is slower to them than the external observer so a decay of a fast moving particle their lifetime before they decay are loner than the predicted time
how are muons created
high energy cosmic rays interact with the nuclei of atoms high in the atmosphere
explain how decay of Muons in the atmosphere explain that fast moving particles experience time slower
Muons are made in our atmosphere and when they decay it takes them a very short time so we shouldn’t find a large number of muons on sea level, but there is a large amount of muons in low altitudes, and that is because when moons are falling back to the surface of earth their moving at a very fast speed so their time is slower therefore they decay slower making them reach earth and decay
what happens if particle decayed in a collision chamber
it wont be detected because we cant place detectors in the chamber
how can particle who have a longer life time than excepted since they are travelling at fast speed be beneficial and bad
- can travel further down than defectors making it be seen better - good
can collide with unexcepted particles - bad