The blue curve in the figure ( " modified proton beam " ) shows how the originally monoenergetic proton beam with the sharp peak is widened by increasing the range of energies, so that a larger tumor volume can be treated.
12.
Medical linacs use monoenergetic electron beams between 4 and 25 MeV, giving an X-ray output with a spectrum of energies up to and including the electron energy when the electrons are directed at a high-density ( such as tungsten ) target.
13.
Since the energy of a thermal neutron is relatively low, charged particle reactions are discrete ( i . e ., essentially monoenergetic and lie within a narrow bandwidth of energies ) while other reactions such as gamma reactions will span a broad energy range, it is possible to discriminate among the sources.
14.
A similar concept is the tenth-value layer or TVL . The TVL is the average amount of material needed to absorb 90 % of all radiation, i . e ., to reduce it to a tenth of the original intensity . 1 TVL is greater than or equal to log 2 ( 10 ) or approximately 3.32 HVLs, with equality achieved for a monoenergetic beam.
