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Yr 13 Physics 08 - Nuclear And Particle Physics > Particle Reactions > Flashcards

Particle Reactions Flashcards

1
Q

what conservations need to be upheld during a reaction involving particles

A
  • the conservation of mass + energy
  • the conservation of momentum
  • the conservation of charge
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2
Q

why is it difficult to confirm mass/energy conservations

A
  • because the reaction can overcome any apparent mass difference in different ways
  • such as the particles having more kinetic energy
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3
Q

regarding the particles and forces topic, what numbers must also be conserved

A
  • baryon number

- lepton number

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4
Q

what would be the product of 235/92 uranium (U) going through alpha decay (you dont need to know the element itself just the numbers)

A
  • an alpha particle has an atomic mass of 4 and number of 2
  • 235 - 4 = 231
  • 92 - 2 = 90
  • 235/92 U = 4/2 a + 231/90 X
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5
Q

what is the principle we have used in order to decipher the decay of uranium

A
  • the conservation of charge

- 92 on the left = 90 + 2 on the right

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6
Q

what would be the product of 14/6 C going through beta minus decay

A
  • a beta- particle has an atomic mass of 0 and number of -1
  • 14 - 0 = 14
  • 6 - (-1) = 7
  • 14/6 C = 14/7 N + 0/-1 b- +0/0 v-bar(e)
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7
Q

what do i mean by v-bar(e)

A
  • v(e) is the symbol for an electron neutrino
  • so v-bar(e) is saying that theres a bar above the v
  • indicating an anti-electron neutrino
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8
Q

why are anti-neutrinos like that one almost impossible to observe

A
  • they are almost massless and have no charge

- so they really hard to detect

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9
Q

what was the evidence for neutrinos or anti-neutrinos also being emitted during beta decays

A
  • the same isotope going through the same beta decay shouldve given the beta particle the same kinetic energy all the time
  • however this wasnt the case, the beta particles had a range of KEs
  • this suggested that another particle was being emitted from the isotope with some KE
  • these particles were the neutrinos
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10
Q

what is important to note about the relationship between the beta particle and the emitted neutrino

A
  • for the same isotope going through the same beta decay

- the sum of the beta and neutrino particles KE was always the same

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11
Q

what is the lepton number of all the leptons we mentioned in the earlier deck (electron / muon / tau)

A

1

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12
Q

what is the baryon number of all the leptons we mentioned in the earlier deck (electron / muon / tau)

A

0

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13
Q

what is the lepton number of all the anti-particles of the leptons mentioned earlier

A

-1

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14
Q

what is the baryon number of all the anti-particles of the leptons mentioned earlier

A

0

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15
Q

what are the lepton and baryon numbers of a proton

A
  • lepton number = 0

- baryon number = +1

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16
Q

what are the lepton and baryon numbers of a neutron

A
  • lepton number = 0

- baryon number = +1

17
Q

what is the charge, lepton and baryon numbers of a neutral pion, pi(0)

A
  • charge = 0
  • lepton number = 0
  • baryon number = 0
18
Q

what is the charge, lepton and baryon numbers of a pi-plus particle, pi+

A
  • charge = +1
  • lepton number = 0
  • baryon number = 0
19
Q

what are the lepton and baryon numbers of a down quark

A
  • lepton number = 0

- baryon number = +1/3

20
Q

what are the charges, lepton and baryon numbers of a xi-minus particle

A
  • charge = -1
  • lepton number = 0
  • baryon number = +1
21
Q

cba to write em all, so what should you know about the charges, lepton and baryon numbers of all of their anti-aprticles

A

its just the same number but with the opposite sign

22
Q

what other property / particle needs to be conserved in reactions

A
  • strangeness

- aka the strange quark

23
Q

what are the strangeness numbers of a strange quark and anti-strange quark

A
  • strange quark = -1

- anti-strange quark = +1

24
Q

what is the strangeness number of all other particles

A

0

25
Q

given that the time for particles moving at relativistic speeds would be slower than normal, what does that mean about what happens to their lifetimes

A

they would be longer than our theoretical predictions

26
Q

what is alpha decay

A

the radioactive process in which a particle combination of two neutrons is ejected from an nucleus

27
Q

what is beta-minus decay

A
  • the radioactive process in which a nuclear neutron changes into a proton
  • and an electron is ejected from the nucleus

Yr 13 Physics 08 - Nuclear And Particle Physics (11 decks)

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