7C.4 Particle Reactions Flashcards

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1
Q

what is conserved in particle reactions

A
  1. energy/mass
  2. momentum
  3. charge
  4. lepton numbers
  5. baryon number
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2
Q

why is it hard to check of energy and momentum have been conserved in particle reactions

A

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

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3
Q

what is an alpha particle decay

A

the radioactive process in which a particle combination of 2 protons and two neutrons is released from the nucleus

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4
Q

what is the beta-minus decay

A

the radioactive process to which a nuclear neutron changes to a proton, and an electron is ejected from the nucleus

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5
Q

what is the alpha and beta decay equation

A

108

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6
Q

why is the anti-electron neutrino in beta-minus decay

A

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

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7
Q

in beta decay we can have two beta particles which are

A

either beta + or beta -

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8
Q

what is a baryon number

A

the quantum number for barons where as proton has B=1 for anti baryon B = -1

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9
Q

each quark has a baryon number of

A

+1/3 and for anti - 1/3

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10
Q

what is the lepton number

A

the quantum number of leptons L= 1 for anti leptons L = -1

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11
Q

mesons baryon number is

A

0 since its made from a quark and a anti quark

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12
Q

what is strangeness

A

a quantum number for strange quarks where S=-1 and anti S = +1

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13
Q

strangeness is conserved in

A

strong and electromagnetic forces

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14
Q

Einstein claimed that for fast moving electrons time

A

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

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15
Q

how are muons created

A

high energy cosmic rays interact with the nuclei of atoms high in the atmosphere

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16
Q

explain how decay of Muons in the atmosphere explain that fast moving particles experience time slower

A

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

17
Q

what happens if particle decayed in a collision chamber

A

it wont be detected because we cant place detectors in the chamber

18
Q

how can particle who have a longer life time than excepted since they are travelling at fast speed be beneficial and bad

A
  1. can travel further down than defectors making it be seen better - good

can collide with unexcepted particles - bad