Common Units of Measure
Electrical Quantities
| Symbol | Name / Meaning | Notes (JACoW usage) |
|---|
| A | ampere | electric current |
| mA | milliampere | common for beam current |
| μA | microampere | use Greek mu, not "u" |
| C | coulomb | electric charge |
| V | volt | electric potential |
| mV | millivolt | |
| kV | kilovolt | |
| MV | megavolt | used for RF cavities and acceleration |
| V/m | volt per meter | electric field gradient |
| Ω | ohm | electrical resistance |
| W | watt | power |
| kW | kilowatt | |
| MW | megawatt | used for RF and beam power |
Energy, Mass, Momentum
| Symbol | Name / Meaning | Notes (JACoW usage) |
|---|
| eV | electronvolt | preferred energy unit |
| keV | kilo-electronvolt | |
| MeV | mega-electronvolt | |
| GeV | giga-electronvolt | |
| TeV | tera-electronvolt | |
| J | joule | SI unit; use sparingly |
| kg | kilogram | mass |
| m₀ | rest mass | variable, not a unit |
| p | momentum | variable, not a unit |
Time and Frequency
| Symbol | Name / Meaning | Notes (JACoW usage) |
|---|
| s | second | |
| ms | millisecond | |
| μs | microsecond | use "μs", not "msec" |
| ns | nanosecond | |
| ps | picosecond | |
| Hz | hertz | |
| kHz | kilohertz | |
| MHz | megahertz | |
| GHz | gigahertz | RF systems |
Length and Geometry
| Symbol | Name / Meaning | Notes (JACoW usage) |
|---|
| m | meter | |
| cm | centimeter | |
| mm | millimeter | |
| μm | micrometer (micron) | preferred form |
| nm | nanometer | |
| Å | angstrom | acceptable for atomic scales |
| m² | square meter | area |
| cm² | square centimeter | luminosity usage |
Motion and Forces
| Symbol | Name / Meaning | Notes (JACoW usage) |
|---|
| m/s | meter per second | velocity |
| m/s² | meter per second squared | acceleration |
| N | newton | force |
| Pa | pascal | pressure (SI) |
| bar | bar | vacuum systems (acceptable) |
Magnetic and RF Quantities
| Symbol | Name / Meaning | Notes (JACoW usage) |
|---|
| T | tesla | magnetic field strength |
| mT | millitesla | not megatonne |
| G | gauss | 1 T = 10⁴ G (legacy) |
| H/m | ampere per meter | magnetic field intensity |
| Wb | weber | magnetic flux |
| Q | quality factor | RF cavities; dimensionless |
Beam and Accelerator Quantities
(Variables — not units, but commonly used)
| Symbol | Meaning | Notes |
|---|
| ε | emittance | often mm·mrad or π mm·mrad |
| β | beta function (Twiss) | unit: meter |
| α | alpha (Twiss) | dimensionless |
| γ | gamma (Twiss) | dimensionless |
| σ | beam size | unit: meter |
| I | beam current | unit: ampere |
| L | luminosity | cm⁻²·s⁻¹ |
| ρ | bending radius | unit: meter |
| Eₐcc | accelerating gradient | MV/m |
SI Prefixes
| Prefix | Symbol | Factor |
|---|
| atto | a | 10⁻¹⁸ |
| femto | f | 10⁻¹⁵ |
| pico | p | 10⁻¹² |
| nano | n | 10⁻⁹ |
| micro | μ | 10⁻⁶ |
| milli | m | 10⁻³ |
| kilo | k | 10³ |
| mega | M | 10⁶ |
| giga | G | 10⁹ |
| tera | T | 10¹² |
