physics 1 chapter 32, Lecture notes of Physics

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Chapter 32

Ionizing Radiation,Nuclear Energy, andElementary Particles

32.1^ Biological Effects of Ionizing Radiation^ Ionizing radiation

consists of photons and/or moving particles that have

sufficient energy to knock and electron out of an atom or molecule, thusforming an ion. Exposure

is a measure of the ionizing radiation produced in air by X-rays or γ-rays.In passing through the air, the beam produces positive ions whose totalcharge is

q. Exposure is the charge per unit mass of the air.

q   m 

×

=^

−^410

roentgens)(in

Exposure

32.1^ Biological Effects of Ionizing Radiation

To compare the damage produced by different types of radiation,the^ relative biological effectiveness

(RBE) is used.

effect biologicalsame the

producesthat radiationof Dose

effect biological certaina pruduces

thatrays- XkeV- (^200) of Dose RBE^ =

32.1^ Biological Effects of Ionizing Radiation

The product of the absorbed dose and the RBE is the

biologically

equivalent dose:

RBE

dose

Absorbed

dose

equivalently

Biological

×

32.2^ Induced Nuclear Reactions

Example 3

An Induced Nuclear Transmutation

An alpha particle strikes an aluminum nucleus. As a result,and unknown nucleus and a neutron are produced.

n X D He^

(^10)

2713 4 2

→ +^

A Z P

32.2^ Induced Nuclear Reactions

An induced nuclear reaction in whichuranium is transmuted into plutonium.

32.3^ Nuclear Fission^ Conceptual Example 5

Thermal Neutrons Versus Thermal

Protons or Alpha Particles Why is it possible for a thermal neutron to penetrate a nucleus, whereasa proton or alpha particle would need a much larger amount of energy?

32.3^ Nuclear Fission

A chain reaction

32.4^ Nuclear Reactors

A nuclear reactor consists of fuel elements, control rods, anda moderator.

32.4^ Nuclear Reactors

The moderator slows neutrons and the control rods absorb neutrons.

32.5^ Nuclear Fusion