CRaTER Science


LET Spectra

Galactic Cosmic Rays

Solar Proton Events

Biological Effects of


Estimate Your Annual
Radiation Exposure

Radiation dose chart
  (interactive & print versions)

Reading Room

Cancer risk from GCR
  (pdf, 2006)
Cell damage detection
  (pdf, 2005)
One-Two Particle Punch
  (website, 2006)
Cosmic Radiation and Bones
  (text, 2005)
Are We Trapped on Earth?
  (website, 2006)
2006 Space Weather Week
  Presentation by H.Spence
  (pdf, 2006)
  describing instrument
  (pdf, 2006)
Radioactive Moon
  (website, 2005)
Proton Inelastic Processes
  (pdf, 2004)
Monte Carlo Simulation
  to Assess True Risk
  (pdf, 2002)
Response of Silicon-based
  LET Spectrometers
  (pdf, 2005)

nasa logo

LET Spectra

Linear energy transfer (or LET), often a non-linear function, is defined as the instantaneous energy deposited into the local environment by a given charged particle per unit of distance (dE/dx).

LET spectra are an important area of study. They tell scientists what sort of energy distribution exists above the Earth's atmosphere and in the interplanetary medium. This information is necessary in order to establish what sort of radiation astronauts will be exposed to during space missions. More importantly, scientists must evaluate the possible biological effects (short- and long-term) of this radiation.