<< Chapter < Page Chapter >> Page >
By the end of this section, you will be able to:
  • Describe and compare three types of nuclear radiation
  • Use nuclear symbols to describe changes that occur during nuclear reactions
  • Describe processes involved in the decay series of heavy elements

Early experiments revealed three types of nuclear “rays” or radiation: alpha ( α ) rays    , beta ( β ) rays    , and gamma ( γ ) rays    . These three types of radiation are differentiated by their ability to penetrate matter. Alpha radiation is barely able to pass through a thin sheet of paper. Beta radiation can penetrate aluminum to a depth of about 3 mm, and gamma radiation can penetrate lead to a depth of 2 or more centimeters ( [link] ).

The figure shows from left to right: paper, metal, concrete and lead. Three types of radiation enter this setup from the left. Alpha radiation does not pass through paper. Beta radiation passes through paper but not through metal. Gamma radiation passes through paper, metal and concrete, but not through lead.
A comparison of the penetration depths of alpha ( α ), beta ( β ), and gamma ( γ ) radiation through various materials.

The electrical properties of these three types of radiation are investigated by passing them through a uniform magnetic field, as shown in [link] . According to the magnetic force equation F = q v × B , positively charged particles are deflected upward, negatively charged particles are deflected downward, and particles with no charge pass through the magnetic field undeflected. Eventually, α rays were identified with helium nuclei ( 4 He ) , β rays with electrons and positrons (positively charged electrons or antielectrons    ), and γ rays with high-energy photons. We discuss alpha, beta, and gamma radiation in detail in the remainder of this section.

Figure shows a C-shaped material labeled lead. A small circle labeled radioactive source is shown in the hollow of the C-shape. Three rays radiate from this source towards the right. One curves upwards and is labeled alpha. One goes straight and is labeled gamma. The third curves downwards and is labeled beta minus. Magnetic field is shown as crosses. Two arrows originate from near the point where the rays emerge from the C-shape. The upwards pointing arrow is labeled F subscript alpha = q subscript alpha v B. The downwards pointing arrow is labeled F subscript beta = q subscript beta v B.
The effect of a magnetic field on alpha ( α ), beta ( β ), and gamma ( γ ) radiation. This figure is a schematic only. The relative paths of the particles depend on their masses and initial kinetic energies.

Alpha decay

Heavy unstable nuclei emit α radiation. In α -particle decay (or alpha decay    ), the nucleus loses two protons and two neutrons, so the atomic number decreases by two, whereas its mass number decreases by four. Before the decay, the nucleus is called the parent nucleus    . The nucleus or nuclei produced in the decay are referred to as the daughter nucleus    or daughter nuclei. We represent an α decay symbolically by

Z A X Z 2 A 4 X + 2 4 H e

where Z A X is the parent nucleus, Z 2 A 4 X is the daughter nucleus, and 2 4 H e is the α particle. In α decay, a nucleus of atomic number Z decays into a nucleus of atomic number Z 2 and atomic mass A 4 . Interestingly, the dream of the ancient alchemists to turn other metals into gold is scientifically feasible through the alpha-decay process. The efforts of the alchemists failed because they relied on chemical interactions rather than nuclear interactions.

Watch alpha particles escape from a polonium nucleus, causing radioactive alpha decay. See how random decay times relate to the half-life. To try a simulation of alpha decay, visit alpha particles

An example of alpha decay is uranium-238:

92 238 U 90 234 X + 2 4 H e .

The atomic number has dropped from 92 to 90. The chemical element with Z = 90 is thorium. Hence, Uranium-238 has decayed to Thorium-234 by the emission of an α particle, written

92 238 U 90 234 T h + 2 4 H e .

Subsequently, 90 234 T h decays by β emission with a half-life of 24 days. The energy released in this alpha decay takes the form of kinetic energies of the thorium and helium nuclei, although the kinetic energy of thorium is smaller than helium due to its heavier mass and smaller velocity.

Questions & Answers

what is force
Afework Reply
The different examples for collision
Afework
What is polarization and there are type
Muhammed Reply
Polarization is the process of transforming unpolarized light into polarized light. types of polarization 1. linear polarization. 2. circular polarization. 3. elliptical polarization.
Eze
Describe what you would see when looking at a body whose temperature is increased from 1000 K to 1,000,000 K
Aishwarya Reply
how is tan ninety minus an angle equals to cot an angle?
Niicommey Reply
please I don't understand all about this things going on here
Jeremiah Reply
What is torque?
Matthew Reply
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment, moment of force, rotational force or turning effect, depending on the field of study.
Teka
Torque refers to the rotational force. i.e Torque = Force × radius.
Arun
Torque is the rotational equivalent of force . Specifically, it is a force exerted at a distance from an object's axis of rotation. In the same way that a force applied to an object will cause it to move linearly, a torque applied to an object will cause it to rotate around a pivot point.
Teka
Torque is the rotational equivalence of force . So, a net torque will cause an object to rotate with an angular acceleration. Because all rotational motions have an axis of rotation, a torque must be defined about a rotational axis. A torque is a force applied to a point on an object about the axis
Teka
When a missle is shot from one spaceship towards another, it leaves the first at 0.950c and approaches the other at 0.750c. what is the relative velocity of the two shipd
Marifel Reply
how to convert:m^3/s^2 all divided by kg to cm^3/s^2
Thibaza Reply
Is there any proof of existence of luminiferious aether ?
Zero Reply
mass conversion of 58.73kg =mg
Proactive Reply
is Space time fabric real
Godawari Reply
What's the relationship between the work function and the cut off frequency in the diagram above?
frankline Reply
due to the upthrust weight of the object varise with force in which the body fall into the water pendincular with the reflection of light with it
Gift
n=I/r
Gift
can someone explain what is going on here
falanga
so some pretty easy physics questions bring em
falanga
what is meant by fluctuated
Olasukanmi Reply
If n=cv then how v=cn? and if n=c/v then how v=cn?
Natanim
convert feet to metre
Mbah Reply
what is electrolysis
Mbah
Electrolysis is the chemical decomposition of electrolyte either in molten state or solution to conduct electricity
Ayomide
class ninekasindhtextbookurdusave
Ayesha Reply
can someone help explain why v2/c2 is =1/2 Using The Lorentz Transformation For Time Spacecraft S′ is on its way to Alpha Centauri when Spacecraft S passes it at relative speed c /2. The captain of S′ sends a radio signal that lasts 1.2 s according to that ship’s clock. Use the Lorentz transformati
Jennifer

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, University physics volume 3. OpenStax CNX. Nov 04, 2016 Download for free at http://cnx.org/content/col12067/1.4
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'University physics volume 3' conversation and receive update notifications?

Ask