User`s manual

Lake Shore MTD Series Cryotest System User’s Manual
Glossary of Terminology A-3
digital data. Pertaining to data in the form of digits or interval quantities. Contrast with analog data.
2
dimensionless sensitivity. Sensitivity of a physical quantity to a stimulus, expressed in dimensionless terms. The
dimensionless temperature sensitivity of a resistance temperature sensor is expressed as S
d
= (T/R)(dR/dT) which is
also equal to the slope of R versus T on a log-log plot, that is S
d
= d lnR / d lnT. Note that the absolute temperature
(in kelvin) must be used in these expressions.
DIN. Deutsches Institut fur Normung.
drift, instrument. An undesired but relatively slow change in output over a period of time, with a fixed reference input.
Note: Drift is usually expressed in percent of the maximum rated value of the variable being measured.
2
DUT. Device Under Test.
electromagnet. A device in which a magnetic field is generated as the result of electrical current passing through a
helical conducting coil. It can be configured as an iron-free solenoid in which the field is produced along the axis of
the coil, or an iron-cored structure in which the field is produced in an air gap between pole faces. The coil can be
water cooled copper or aluminum, or superconductive.
electrostatic discharge (ESD). A transfer of electrostatic charge between bodies at different electrostatic potentials
caused by direct contact or induced by an electrostatic field.
error. Any discrepancy between a computed, observed, or measured quantity and the true, specified, or theoretically
correct value or condition.
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excitation. Either an AC or DC input to a sensor used to produce an output signal. Common excitations include: constant
current, constant voltage, or constant power.
Fahrenheit (°F) Scale. A temperature scale that registers the freezing point of water as 32 °F and the boiling point as
212 °F under normal atmospheric pressure. See Temperature for conversions.
fanout board. A fanout board is a printed circuit board which is used to interconnect the Device-Under-Test (DUT) to the
coax signal lines (via the interface board) in the MTD System. The socket for a particular device package is mounted
on the fanout board and the contacts of the socket are soldered to the board traces. The 50 Ω stripline transmission
traces on the fanout board are gold plated to enhance the electrical connections and to inhibit corrosion.
feedthru. Provides leak-proof (hermetic) access from one volume to another without breaking the integrity of either
space. In Lake Shore equipment, a feedthough is used to provide wiring from the room temperature environment to
the cryogenic environment inside a dewar.
four-lead. measurement technique where one pair of excitation leads and an independent pair of measurement leads
are used to measure a sensor. This method reduces the effect of lead resistance on the measurement.
FPA. Focal Plane Array.
GaAlAs. Gallium-aluminum-arsenide semiconducting material used to make the special Lake Shore TG family of diode
temperature sensors.
gamma. A cgs unit of low-level flux density, where 100,000 gamma equals one oersted, or 1 gamma equals 10
–5
oersted.
gauss (G). The cgs unit for magnetic flux density (B). 1 gauss = 10
–4
tesla. Named for Karl Fredrich Gauss (1777 – 1855)
a German mathematician, astronomer, and physicist.
gaussian system (units). A system in which centimeter-gram-second units are used for electric and magnetic qualities.
general purpose interface bus (GPIB). Another term for the IEEE-488 bus.
germanium (Ge). A common temperature sensing material fabricated from doped germanium to make the Lake Shore
GR family of resistance temperature sensor elements.
gilbert (Gb). A cgs electromagnetic unit of the magnetomotive force required to produce one maxwell of magnetic flux
in a magnetic circuit of unit reluctance. One gilbert is equal to 10/4π ampere-turn. Named for William Gilbert
(1540
– 1603), an English physicist; hypothesized that the earth is a magnet.
gilbert per centimeter. Practical cgs unit of magnet intensity. Gilberts per cm are the same as oersteds.
Greek alphabet. The Greek alphabet is defined as follows:
Alpha α Α Iota ι Ι Rho ρ Ρ
Beta β Β Kappa κ Κ Sigma σ Σ
Gamma γ Γ Lambda λ Λ Tau τ Τ
Delta δ ∆ Mu µ Μ Upsilon υ Υ
Epsilon ε Ε Nu ν Ν Phi φ Φ
Zeta ζ Ζ Xi ξ Ξ Chi χ Χ
Eta η Η Omicron ο Ο Psi ψ Ψ
Theta θ Θ Pi π Π Omega ω Ω