Value-items in FESA properties should be labeld by their units. Units should be given as extra value-items with the suffix _units, e.g. a value item current should be accompanied by a value item current_units.

Units must be given as string, as identified in the following tables in the row Unit Name.

Common SI-Units

Quantity Unit SI-Units Unit Name
length meter   m
mass kilogramm   kg
time second   s
electrical current ampere   A
temperature kelvin   K
electrical charge coulomb A s C
electrical voltage voltage W / A = m² kg / s³ A V
magnetic field strength tesla Wb / m² = kg / s² A T
frequency hertz 1 / s Hz
pressure pascal N / m² = kg / ms² Pa

Convenience Units

Whenever possible, data should be labeled by SI base units, without prefixes like milli, micro, kilo (the base unit of the mass is kg), However, in some cases special units and specific naming would be very helpful:
  • In some cases the data has no units but it would be helpfull to indicate the type of the quantity as 'unit name', E.g. in beam instrumentation, often pulses were counted (acquisition of the output singnal of a photomultiplier, acquisition of the output of a voltage to frequency converter, or other). When such result are presented directly, they should be labeled as counts.
  • In some cases, equipment shows data on build-in displays in units other than SI base units. Converting data on the front-ends to SI base units would result in different values. As long as the difference is in the decimal power only this is no severe problem. But comparison of values would be made difficult when, e.g., one is displayed in minutes and the other in seconds. In such cases, the units of the equipment's diplays should be used in the FESA class too.

List shall be extended when quantities are used which are not listed.
Quantity Comment Unit Name
counts   cnt
counting rate   cnt/s
volume flux if used on equipment display cm^3/min

Commonly In-House Used Combined Units

List shall be extended when quantities are used which are not listed. Anyhow, most entries are expected to be used rarely on front-end systems.
Quantity Units Unit Name
magnetic rigidity tesla * meter Tm
dipole bending strength tesla * meter Tm
quadrupole focusing strength tesla T
magnetic field gradient tesla / meter T/m
electrical field gradient volt / meter V/m
magnetic ramp rate tesla / second T/s
electrical ramp rate volt per second V/s
frequency ramp rate Hz per second Hz/s
beam energy electron volt eV
beam energy per atomic mass unit electron volt per mass unit eV/u
velocity meter per second m/s
area square meter m^2
volume cubic meter m^3
flow cubic meter per second m^3/s

Other SI-Units

Not expected to be used in properties of front-end Systems. If so, entry should be moved to upper most table.
Quantity Unit SI-Units Unit Name
amount of substance mole     mol
luminous intensity candela     cd
angle radian 1   rad
solid angle steradian 1   sr
force, weight newton kg m / s²   N
energy, work joule N m = m² kg / s²   J
power watt J / s = m² kg / s³   W
electrical capacity farad C / V   F
elektrical resistance ohm V / A = m² kg / s³ A² Ω Ohm
elektrical conductance siemens 1 / Ω = s³ A²/ m² kg   S
magnetical flux weber V s = m² kg / s² A   Wb
inductance henry Wb / A = m² kg / s² A²   H
temperature Celsius degree Celsius K ºC degC
luminance lux lm / m² = cd / m²   lx
redioactivity becquerel 1 / s   Bq
absorbed dose gray J / kg = m² / s²   Gy
equivalent dose sievert J / kg = m² / s²   Sv
katalytic activity katal mol / s   kat
Topic revision: r1 - 03 Sep 2015, UdoKrause
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