# Becquerel (unit)

Physical unit
Unit name Becquerel
Unit symbol ${\ displaystyle \ mathrm {Bq}}$
Physical quantity (s) activity
Formula symbol ${\ displaystyle A; \, a}$
dimension ${\ displaystyle {\ mathsf {T ^ {- 1}}}}$
system International system of units
In SI units ${\ displaystyle \ mathrm {1 \; Bq = {\ frac {1} {s}}}}$
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: ${\ displaystyle A}$

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The units Rutherford (1 rd = 10 6 Bq) and Stat (1 Stat = 1.345 · 10 4 Bq) are further outdated, non- SI -conforming units for the activity.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). ${\ displaystyle \ mathrm {s} ^ {- 1}}$

## 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).