Gamma

For Latin ɣ, see Latin gamma. For other uses, see Gamma (disambiguation).

Gamma (uppercase Γ, lowercase γ; Greek: Γάμμα Gámma) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. It was derived from the Phoenician letter Gimel . Letters that arose from gamma include the Roman C and G and the Cyrillic letters Г and Ґ.

Uses

Greek

The alphabet on a black figure vessel, with a Λ-shaped gamma

In Ancient Greek, gamma represented a voiced velar stop /ɡ/. In Modern Greek, it represents a voiced fricative. It is realized either as a palatal /ʝ/ (before a front vowel, /e, i/), or as a velar /ɣ/ (in all other environments).

Both in Ancient and in Modern Greek, before other velars (κ, χ, ξ k, kh, ks), gamma represents a velar nasal /ŋ/. A double gamma γγ represents the sequence /ŋɡ/ (phonetically varying [ŋɡ~ɡ]) or /ŋɣ/.

International Phonetic Alphabet

In the International Phonetic Alphabet, lowercase gamma (ɣ) represents the voiced velar fricative. A lowercase gamma that lies above the baseline rather than crossing it (ɤ) represents the close-mid back unrounded vowel.

Mathematics and science

Lower case

The lower-case letter $\gamma$ is used as a symbol for:

• Chromatic number of a graph, sometimes $\chi$ (Chi) is used, which is also used for the Euler characteristic
• Gamma radiation in nuclear physics
• The photon, the elementary particle of light
• Surface energy in materials science
• The Lorentz factor in theory of relativity
• The heat capacity ratio Cp/Cv in thermodynamics
• The activity coefficient in thermodynamics
• The gyromagnetic ratio in electromagnetism
• Gamma oscillation in neuroscience
• Gamma motoneurons in neuroscience
• Gamma is a non-SI metric unit of measure of mass equal to one microgram (1 μg). This always-rare use is currently deprecated.
• Gamma is also a non-SI unit of measure of magnetic flux density, sometimes used in geophysics, equal to 1 nanotesla (nT).
• The power by which the luminance of an image is increased in gamma correction
• The Euler–Mascheroni constant
• In mechanical engineering:
  • Specific weight
  • The shear rate of a fluid is represented by a lower case gamma with a dot above it: $\dot \gamma$
  • Austenite (also known as γ-iron), a metallic non-magnetic allotrope or solid solution of iron.
• The gamma carbon is the third carbon attached to a functional group in Organic Chemistry and Biochemistry nomenclature; see Alpha and beta carbon

Upper case

The upper-case letter $\Gamma$ is used as a symbol for:

• In mathematics, the gamma function (usually written as $\Gamma$-function) is an extension of the factorial to complex numbers
• In probability theory and statistics, the gamma distribution is a two-parameter family of continuous probability distributions.
• Circulation in fluid mechanics
• As reflection coefficient in physics and electrical engineering
• The tape alphabet of a Turing machine
• The Feferman–Schütte ordinal Γ₀

Meteorology

• Gamma was one of the names used in the 2005 Atlantic hurricane season as Tropical Storm Gamma.

Technical notes

HTML

The HTML entities for uppercase and lowercase gamma are Γ and γ.

Unicode

• Greek Gamma

Character	Γ		γ		ᴦ		ᵞ		ᵧ
Unicode name	GREEK CAPITAL LETTER GAMMA		GREEK SMALL LETTER GAMMA		GREEK LETTER SMALL CAPITAL GAMMA		MODIFIER LETTER SMALL GREEK GAMMA		GREEK SUBSCRIPT SMALL LETTER GAMMA
Encodings	decimal	hex	decimal	hex	decimal	hex	decimal	hex	decimal	hex
Unicode	915	U+0393	947	U+03B3	7462	U+1D26	7518	U+1D5E	7527	U+1D67
UTF-8	206 147	CE 93	206 179	CE B3	225 180 166	E1 B4 A6	225 181 158	E1 B5 9E	225 181 167	E1 B5 A7
Numeric character reference	Γ	Γ	γ	γ	ᴦ	ᴦ	ᵞ	ᵞ	ᵧ	ᵧ
Named character reference	Γ		γ

• Coptic Gamma

Character	Ⲅ		ⲅ
Unicode name	COPTIC CAPITAL LETTER GAMMA		COPTIC SMALL LETTER GAMMA
Encodings	decimal	hex	decimal	hex
Unicode	11396	U+2C84	11397	U+2C85
UTF-8	226 178 132	E2 B2 84	226 178 133	E2 B2 85
Numeric character reference	Ⲅ	Ⲅ	ⲅ	ⲅ

• Latin / phonetic Gamma

Character	Ɣ		ɣ		ˠ		ɤ
Unicode name	LATIN CAPITAL LETTER GAMMA		LATIN SMALL LETTER GAMMA		MODIFIER LETTER SMALL GAMMA		LATIN SMALL LETTER RAMS HORN
Encodings	decimal	hex	decimal	hex	decimal	hex	decimal	hex
Unicode	404	U+0194	611	U+0263	736	U+02E0	612	U+0264
UTF-8	198 148	C6 94	201 163	C9 A3	203 160	CB A0	201 164	C9 A4
Numeric character reference	Ɣ	Ɣ	ɣ	ɣ	ˠ	ˠ	ɤ	ɤ

• CJK Square Gamma

Character	㌏
Unicode name	SQUARE GAMMA
Encodings	decimal	hex
Unicode	13071	U+330F
UTF-8	227 140 143	E3 8C 8F
Numeric character reference	㌏	㌏

• Technical / Mathematical Gamma

Character	ℾ		ℽ		𝚪		𝛄		𝛤		𝛾
Unicode name	DOUBLE-STRUCK CAPITAL GAMMA		DOUBLE-STRUCK SMALL GAMMA		MATHEMATICAL BOLD CAPITAL GAMMA		MATHEMATICAL BOLD SMALL GAMMA		MATHEMATICAL ITALIC CAPITAL GAMMA		MATHEMATICAL ITALIC SMALL GAMMA
Encodings	decimal	hex	decimal	hex	decimal	hex	decimal	hex	decimal	hex	decimal	hex
Unicode	8510	U+213E	8509	U+213D	120490	U+1D6AA	120516	U+1D6C4	120548	U+1D6E4	120574	U+1D6FE
UTF-8	226 132 190	E2 84 BE	226 132 189	E2 84 BD	240 157 154 170	F0 9D 9A AA	240 157 155 132	F0 9D 9B 84	240 157 155 164	F0 9D 9B A4	240 157 155 190	F0 9D 9B BE
UTF-16	8510	213E	8509	213D	55349 57002	D835 DEAA	55349 57028	D835 DEC4	55349 57060	D835 DEE4	55349 57086	D835 DEFE
Numeric character reference	ℾ	ℾ	ℽ	ℽ	𝚪	𝚪	𝛄	𝛄	𝛤	𝛤	𝛾	𝛾

Character	𝜞		𝜸		𝝘		𝝲		𝞒		𝞬
Unicode name	MATHEMATICAL BOLD ITALIC CAPITAL GAMMA		MATHEMATICAL BOLD ITALIC SMALL GAMMA		MATHEMATICAL SANS-SERIF BOLD CAPITAL GAMMA		MATHEMATICAL SANS-SERIF BOLD SMALL GAMMA		MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL GAMMA		MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL GAMMA
Encodings	decimal	hex	decimal	hex	decimal	hex	decimal	hex	decimal	hex	decimal	hex
Unicode	120606	U+1D71E	120632	U+1D738	120664	U+1D758	120690	U+1D772	120722	U+1D792	120748	U+1D7AC
UTF-8	240 157 156 158	F0 9D 9C 9E	240 157 156 184	F0 9D 9C B8	240 157 157 152	F0 9D 9D 98	240 157 157 178	F0 9D 9D B2	240 157 158 146	F0 9D 9E 92	240 157 158 172	F0 9D 9E AC
UTF-16	55349 57118	D835 DF1E	55349 57144	D835 DF38	55349 57176	D835 DF58	55349 57202	D835 DF72	55349 57234	D835 DF92	55349 57260	D835 DFAC
Numeric character reference	𝜞	𝜞	𝜸	𝜸	𝝘	𝝘	𝝲	𝝲	𝞒	𝞒	𝞬	𝞬

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.

See also

• Г, г - Ge (Cyrillic)
• G, g - Latin