Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 21: Problem 51

How does a Geiger counter work?

Short Answer

Expert verified
A Geiger counter works by using ionising radiation to initiate a cascade of ionisations in a gas-filled tube (the Geiger-Muller tube). This cascade, known as a Townsend Avalanche, results in a measurable current pulse. This response is interpreted by a processing unit and provides a readout of the radiation level in terms of either 'counts per minute' or 'radiation dose per hour'.

Step by step solution

01

Understanding the Device

A Geiger counter, also known as a Geiger-Muller counter, is a device used for the detection and measurement of all types of radiation: alpha, beta and gamma radiation. It was named after its inventors, Hans Geiger and Walther Müller.
02

Construction of the Geiger Counter

The basic design of a Geiger counter consists of two main parts: a Geiger-Muller tube, and a processing and display unit. The Geiger-Muller tube is the sensing element, filled with an inert gas like helium or argon at low pressure. This tube also contains a thin metal wire along its center. The wire serves as an anode, while the wall of the tube serves as a cathode, thus forming a capacitor. The processing and display unit interprets the signals from the Geiger-Muller tube and provides a readout.
03

Working principle of the Geiger Counter

The operation is based on ionizing radiation, which penetrates the wall of the tube and ionizes the gas inside. When the inert gas atoms are ionized, they emit positively charged ions and electrons. These electrons are pulled toward the wire (anode), and as they accelerate, more gas atoms are ionized. This creates a cascading effect known as a Townsend Avalanche, resulting in a rapid discharge and a current pulse across the tube. This pulse is then interpreted by the processing unit into a readout.
04

Measuring Radiation

The Geiger counter measures radiation in terms of 'counts per minute' (CPM) or 'radiation dose per hour' (mR/hr or μSv/h), indicating the number of ionization events per minute or the amount of radiation dose that a person would receive per hour standing at the place where the measurement is taken.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

In the thorium decay series, thorium- 232 loses a total of \(6 \alpha\) particles and \(4 \beta\) particles in a 10 -stage process. What is the final isotope produced?

A radioactive substance undergoes decay as: $$ \begin{array}{cc} \text { Time (days) } & \text { Mass (g) } \\ \hline 0 & 500 \\ 1 & 389 \\ 2 & 303 \\ 3 & 236 \\ 4 & 184 \\ 5 & 143 \\ 6 & 112 \end{array} $$ Calculate the first-order decay constant and the halflife of the reaction.

The quantity of a radioactive material is often measured by its activity (measured in curies or millicuries) rather than by its mass. In a brain scan procedure, a 70 -kg patient is injected with \(20.0 \mathrm{mCi}\) of \({ }^{99 \mathrm{~m}} \mathrm{Tc}\) which decays by emitting \(\gamma\) -ray photons with a halflife of \(6.0 \mathrm{~h}\). Given that the \(\mathrm{RBE}\) of these photons is 0.98 and only two-thirds of the photons are absorbed by the body, calculate the rem dose received by the patient. Assume all of the \({ }^{99 \mathrm{~m}}\) Tc nuclei decay while in the body. The energy of a gamma photon is \(2.29 \times 10^{-14} \mathrm{~J}\).

Discuss factors that lead to nuclear decay.

Cobalt- 60 is an isotope used in diagnostic medicine and cancer treatment. It decays with \(\gamma\) ray emission. Calculate the wavelength of the radiation in nanometers if the energy of the \(\gamma\) ray is \(2.4 \times 10^{-13} \mathrm{~J} / \mathrm{photon}\)
See all solutions

Recommended explanations on Chemistry Textbooks

Ionic and Molecular Compounds

Read Explanation

Organic Chemistry

Read Explanation

Chemical Analysis

Read Explanation

Chemical Reactions

Read Explanation

Making Measurements

Read Explanation

Kinetics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free