Unit 2: Radiocarbon Dating

Question 1

How is Carbon-14 produced?

Answer 1

Generated by cosmic rays colliding with nitrogen (Mostly 14N) to produce 14C

Question 2

After how many half-lives is Carbon-14 no longer useful?

Answer 2

After 10 half lives of 14C you get lots of errors when trying to measure the amount due to how little there is

Question 3

What is 1 Bq?

Answer 3

1 disintegration per second

Question 4

What is a curie?

Answer 4

A unit of activity equal to 3.7x10¹⁰ disintegration per second

Question 5

What is 1 curie equal to in Bq?

Answer 5

37 billion Bq

Question 6

How can you detect radiation?

Answer 6

• Ionisation counter
• Scintillation counter
• Accelerator Mass Spectrometry

Question 7

What is the equation for t1/2

Answer 7

t1/2 = ln2/k
t1/2 = 0.693/k

Question 8

What is the equation for ln2?

Answer 8

ln2 = k x t1/2

Question 9

What is the equation for -Ln2

Answer 9

-k x t1/2

Question 10

What is ln x^y equal to?

Answer 10

y ln x

Question 11

What is the equation for ln2^-1 ?

Answer 11

-k x t1/2

Question 12

What is the equation for ln(1/2)

Answer 12

-k x t1/2

Question 13

After one half life (t1/2) what is the equation for N?

Answer 13

1/2 N₀

Question 14

ln(N/N0) = ?

Answer 14

-k x t

Question 15

-k x t = ?

Answer 15

ln(N/N0)

Question 16

N/No = ?

Answer 16

e^{-k x t}

Question 17

e^-kt = ?

Answer 17

N/No

Question 18

N = ?

Answer 18

N₀ x e^{-k x t}

Question 19

N0 x e^ -k x t = ?

Answer 19

N

Question 20

N_t

Answer 20

Number of nuclei at time (t)

Question 21

N₀

Answer 21

Initial number of nuclei

Question 22

n

Answer 22

Number of half lives

Question 23

Equation for N_t

Answer 23

N_t = N₀ x (1/2)ⁿ

Question 24

N

Answer 24

Number of nuclei

Question 25

How does the scintillator work?

Answer 25

The scintillator material emits light that is collected in photomultiplier tubes

Question 26

What is Accelertor Mass Spectrometry good for?

Ultrasensitive, C

Answer 26

• AMS is ultrasensitive isotope ratio mass spectrometry of small prepared samples
• Most advanced way of measuring 14C

Question 27

What isotopes does accelerator mass spectrometry measure?

Answer 27

Long-lived radioisotopes that are naturally lowly abundant due to their instability, yet difficult to measure by their infrequent decay

Question 28

How are ions characterised in accelerator mass spectrometry?

Conventional

Answer 28

The ions are characterised by combined conventional mass spectrometry and high-energy collisions within the accelerator and in a final detector.

Question 29

What are the spectrometers based on in accelerator mass spectrometry?

Particle accelerators

Answer 29

Spectrometers are based on tandem electrostatic particle accelerators for energising ionised sample atoms to 10s MeV

Question 30

How does accelerator mass spectrometry work?

Counts

Answer 30

AMS counts the number of atoms in the sample

Question 31

Activity / Rate of decay

Answer 31

activity = rate of decay = k x N

Question 32

k

Answer 32

k is the decay constant and is characteristic of the radionuclide

Question 33

Activity

Answer 33

Activity is proportional to the number of nuclei

Question 34

How does scintillation counter work?

Infrequent

Answer 34

Scintillation counters measure the infrequent radioactive decay events in the sample

Question 35

What is activity?

Answer 35

Is the number of nuclear disintegrations per unit time occurring in a radioactive material

Question 36

What is Bq?

Answer 36

The becquerel (Bq) is the unit of radioactivity.