7C.4 Particle Reactions

Question 1

what is conserved in particle reactions

Answer 1

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

Question 2

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

Answer 2

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

Question 3

what is an alpha particle decay

Answer 3

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

Question 4

what is the beta-minus decay

Answer 4

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

Question 5

what is the alpha and beta decay equation

Answer 5

108

Question 6

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

Answer 6

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

Question 7

in beta decay we can have two beta particles which are

Answer 7

either beta + or beta -

Question 8

what is a baryon number

Answer 8

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

Question 9

each quark has a baryon number of

Answer 9

+1/3 and for anti - 1/3

Question 10

what is the lepton number

Answer 10

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

Question 11

mesons baryon number is

Answer 11

0 since its made from a quark and a anti quark

Question 12

what is strangeness

Answer 12

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

Question 13

strangeness is conserved in

Answer 13

strong and electromagnetic forces

Question 14

Einstein claimed that for fast moving electrons time

Answer 14

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

Question 15

how are muons created

Answer 15

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

Question 16

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

Answer 16

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

Question 17

what happens if particle decayed in a collision chamber

Answer 17

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

Question 18

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

Answer 18

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

can collide with unexcepted particles - bad