Week 8 - Radioactivity and Nuclear Interaction With Matter Flashcards

• Explain the mechanism of radioactive decay • Understand nuclear decay law • Calculate the half life, decay constant, and radioactivity • Understand the mechanism of alpha decay, beta decay and gamma decay

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1
Q

Define Radioactivity; what causes it?

A

Spontaneous emission of radiation as a result of decay / disintegration of unstable nuclei

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2
Q

Define a half-life

A

Time it takes for half of any given number of radioactive nuclei decay

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3
Q

Define the types of radioactivity; their penetrating ability (energy) and provide material examples

(3)

A

Alpha particles, Beta particles and Gamma rays; LOW - barely penetrating (piece of paper), MEDIUM - a little bit of penetration (few mm of Al), HIGH - highly penetrable (several cm of lead)!

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4
Q

What are the rules of decay?

(3)

A
  1. The sum of A (mass numbers) MUST BE THE SAME on both sides of the equation
  2. the sum of Z (atomic numbers) MUST BE THE SAME on both sides of the equation
  3. Conservation of mass-energy nd conservation of momentum must hold (stay true)
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5
Q
A
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5
Q

Define a decay constant; what is the formula?

A

the # of particles that decay in a given time;
ΔN = -λ N Δt

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6
Q

Define the decay rate; what is the formula?

A

The decay rate or activity, R, of a sample is defined as the number of decays per SECOND
R= ΔN / Δt = λN

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7
Q

What does λ represent?

A

λ represents the decay constant; the rate at which a material will decay

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8
Q

difference between x-ray and gamma ray?

A

gamma produced inside nucleus;
x-ray (refer to recording)

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9
Q
A
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