Skip to main content
  • Other Publications
    • Philosophical Transactions B
    • Proceedings B
    • Biology Letters
    • Open Biology
    • Philosophical Transactions A
    • Proceedings A
    • Royal Society Open Science
    • Interface
    • Interface Focus
    • Notes and Records
    • Biographical Memoirs

Advanced

  • Home
  • Content
    • Latest issue
    • All content
    • Subject collections
    • Special features
    • Videos
  • Information for
    • Authors
    • Reviewers
    • Readers
    • Institutions
  • About us
    • About the journal
    • Editorial board
    • Author benefits
    • Policies
    • Citation metrics
    • Publication times
    • Open access
  • Sign up
    • Subscribe
    • eTOC alerts
    • Keyword alerts
    • RSS feeds
    • Newsletters
    • Request a free trial
  • Submit
You have accessRestricted access

The existence of a neutron

J. Chadwick, F. R. S.
Published 1 June 1932.DOI: 10.1098/rspa.1932.0112
James Chadwick
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Info & Metrics
  • eLetters
  • Review History
  • PDF
Loading

Extract

§ 1. It was shown by Bothe and Becker that some light elements when bombarded by α-particles of polonium emit radiations which appear to be of the γ-ray type. The element beryllium gave a particularly marked effect of this kind, and later observations by Bothe, by Mme. Curie-Joliot and by Webster showed that the radiation excited in beryllium possessed a penetrating power distinctly greater than that of any γ-radiation yet found from the radioactive elements. In Webster’s experiments the intensity of the radiation was measured both by means of the Geiger-Müller tube counter and in a high pressure ionisation chamber. He found that the beryllium radiation had an absorption coefficient in lead of about 0·22 cm.-1 as measured under his experimental conditions. Making the necessary corrections for these conditions, and using the results of Gray and Tarrant to estimate the relative contributions of scattering, photoelectric absorption, and nuclear absorption in the absorption of such penetrating radiation, Webster concluded that the radiation had a quantum energy of about 7 × 106 electron volts. Similarly he found that the radiation from boron bombarded by α-particles of polonium consisted in part of a radiation rather more penetrating than that from beryllium, and he estimated the quant um energy of this component as about 10 X 106 electron volts. These conclusions agree quite well with the supposition that the radiations arise by the capture of the α-particle into the beryllium (or boron) nucleus and the emission of the surplus energy as a quantum of radiation. The radiations showed, however, certain peculiarities, and at my request the beryllium radiation was passed into an expansion chamber and several photographs were taken. No unexpected phenomena were observed though, as will be seen later, similar experiments have now revealed some rather striking events. The failure of these early experiments was partly due to the weakness of the available source of polonium, and partly to the experimental arrangement, which, as it now appears, was not very suitable.

Footnotes

  • This text was harvested from a scanned image of the original document using optical character recognition (OCR) software. As such, it may contain errors. Please contact the Royal Society if you find an error you would like to see corrected. Mathematical notations produced through Infty OCR.

  • Received May 10, 1932.
  • Scanned images copyright © 2017, Royal Society
PreviousNext
Back to top
PreviousNext
1 June 1932
Volume 136, issue 830
  • Table of Contents
  • Index by author
  • Advertising (PDF)
  • Back Matter (PDF)
  • Front Matter (PDF)
Share
The existence of a neutron
J. Chadwick, F. R. S.
Proc. R. Soc. Lond. A 1932 136 692-708; DOI: 10.1098/rspa.1932.0112. Published 1 June 1932
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Connotea logo Facebook logo Google logo Mendeley logo
Email

Thank you for your interest in spreading the word on Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
The existence of a neutron
(Your Name) has sent you a message from Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences
(Your Name) thought you would like to see the Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences web site.
Print
Manage alerts

Please log in to add an alert for this article.

Sign In to Email Alerts with your Email Address
Citation tools

The existence of a neutron

J. Chadwick, F. R. S.
Proc. R. Soc. Lond. A 1932 136 692-708; DOI: 10.1098/rspa.1932.0112. Published 1 June 1932

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Download

Article reuse

Get Permission

  • Article
  • Info & Metrics
  • eLetters
  • Review History
  • PDF

Related articles

Cited by

Powered by MathJaxLearn about displayed equations in Proceedings A

PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON A: MATHEMATICAL, PHYSICAL AND ENGINEERING SCIENCES

  • PROCEEDINGS A
    • About this journal
    • Contact information
    • Purchasing information
    • Submit
    • Author benefits
    • Open access membership
    • Recommend to your library
    • FAQ
    • Help

Royal society publishing

  • ROYAL SOCIETY PUBLISHING
    • Our journals
    • Open access
    • Publishing policies
    • Conferences
    • Podcasts
    • News
    • Blog
    • Manage your account
    • Terms & conditions
    • Privacy policy
    • Cookies

The royal society

  • THE ROYAL SOCIETY
    • About us
    • Contact us
    • Fellows
    • Events
    • Grants, schemes & awards
    • Topics & policy
    • Collections
    • Venue hire
1471-2946

Copyright © 2018 The Royal Society