Becquerel (unit)


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Physical unit
Unit name Becquerel
Unit symbol
Physical quantity (s) activity
Formula symbol
dimension
system International system of units
In SI units
Named after Antoine Henri Becquerel
Derived from second

Becquerel [ bɛkə'rɛl ], abbreviated to Bq, is the SI unit of the activity of a certain amount of a radioactive substance. The average number of atomic nuclei that decay radioactively per second is given:

1 Bq = 1 s −1 (i.e. one Becquerel corresponds to one radioactive decay per second)

Since 1 Bq is an extremely low activity, very large numerical values ​​occur in practice. Therefore one often uses prefixes for the order of magnitude (mega-, giga-, tera-, ...).

The unit is named after the French physicist Antoine Henri Becquerel , who together with Pierre Curie and Marie Curie received the Nobel Prize for the discovery of radioactivity in 1903 . The Becquerel was adopted in 1975 at the 15th meeting of the General Conference on Weights and Measures as a derived SI unit with a special name in the International System of Units.

Relation to other units

The Becquerel unit replaces the Curie in the International System of Units (SI) . The following relationship exists between these two units:

1 Ci = 3.7 x 10 10  Bq
1 Bq = 2.7 027 · 10 −11  Ci

The following relationship also applies:

1 Bq = 60 dpm ("disintegrations per minute", disintegrations per minute)

The units Rutherford (1 rd = 10 6 Bq) and Stat (1 Stat = 1.345 · 10 4 Bq) are further outdated, non- SI -conforming units for the activity.

At first glance, the Becquerel appears to be identical to the Hertz unit , both are defined as . The difference between the two is that Becquerel measures the mean frequency of a random event (such as radioactive decay), while Hertz measures a non-random, periodic quantity (such as the frequency of a radio wave).

Individual evidence

  1. Hanno Krieger: Fundamentals of radiation physics and radiation protection. 3rd, revised and expanded edition. Vieweg + Teubner, Wiesbaden 2009, ISBN 978-3-8348-0801-1 , Chapter 3.2.1 Activity definitions .
  2. Resolution 8 at the 15th meeting of the Conférence Générale des Poids et Mesures 1975 (accessed on March 3, 2013).