Choose linear energy transfer, path distance or electronic energy loss, then enter the two known values and their units.

Average electronic energy loss over the entered path; assumes constant average LET.

Linear Energy Transfer Formula

Linear energy transfer, or LET, is the energy lost by a charged particle per unit distance traveled. The calculator uses energy loss, distance, and LET as three related values. Choose the value to solve and enter the other two. This is a path-average electronic energy-loss model.

LET = E / d
E = LET × d
d = E / LET
  • LET = linear energy transfer, usually expressed in keV/cm, keV/m, eV/cm, or eV/m
  • E = energy loss of the charged particle due to electron collisions
  • d = total distance traveled by the charged particle

The calculator first converts distance to centimeters and energy loss to keV. LET is converted to keV/cm. It then solves the missing value.

  • To calculate LET: divide energy loss by distance.
  • To calculate energy loss: multiply LET by distance.
  • To calculate distance: divide energy loss by LET.

Supported Units and Base Conversions

The calculator uses cm for distance and keV for energy as its base units.

Input type Unit Conversion to base unit
Distance cm 1 cm = 1 cm
Distance m 1 m = 100 cm
Distance in 1 in = 2.54 cm
Distance ft 1 ft = 30.48 cm
Energy loss keV 1 keV = 1 keV
Energy loss eV 1 eV = 0.001 keV
Energy loss J 1 keV = 1.602176634 × 10−16 J exactly; 1 J ≈ 6.241509074 × 1015 keV

LET Unit Relationships

LET unit Relationship to keV/cm Use case
keV/cm Base LET unit Direct calculation with cm and keV
keV/m Divide by 100 to convert to keV/cm Longer travel distances
eV/cm Multiply by 0.001 to convert to keV/cm Smaller energy loss values
eV/m Multiply by 0.001 and divide by 100 Small energy loss over longer distances

Example Problems

Example 1: Calculate LET

A charged particle loses 500 keV of energy over a distance of 25 cm.

LET = E / d
LET = 500 / 25 = 20 keV / cm

The linear energy transfer is 20 keV/cm.

Example 2: Calculate Energy Loss

A particle has a LET of 12 keV/cm and travels 40 cm.

E = LET × d
E = 12 × 40 = 480 keV

The energy loss is 480 keV.

FAQ

What does linear energy transfer mean?

Linear energy transfer is the amount of energy a charged particle loses per unit distance as it moves through a material. A higher LET means the particle deposits more energy over a shorter path.

Which values do I enter?

Choose the quantity to solve and enter the other two known quantities. Path distance must be positive; energy loss and LET are nonnegative. Solving distance requires positive LET.

Can LET be zero?

LET cannot be zero when calculating distance, because distance is found by dividing energy loss by LET. Division by zero is not valid. A LET of zero would also mean no energy is being transferred per unit length.