Calculate linear energy transfer, distance traveled, or charged particle energy loss by entering any two values with unit conversions.
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. Enter any two values to solve for the third.
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 J = 6.242 × 103 keV in this calculator |
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.
Why do I need to enter exactly two values?
The LET formula has three variables: energy loss, distance, and LET. If you enter any two of them, the third can be solved directly. If you enter fewer than two, there is not enough information. If you enter all three, there is no missing value to calculate.
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.
