Physics and Engineering of Radiation Detection

1.6. General Properties and Sources of Particles and Waves 35

characterisitc x−rays

Bremsstrahlung

x−ray intensity

photon energy

Figure 1.6.4: A typical x-ray tube spectrum showing

Bremsstrahlung continuum and peaks corresponding to charac-

teristic x-rays.

Assuming that the electron velocity is non-relativistic (i.e. ve<< c), we can

write its maximum kinetic energy as

Tmax=

1

2

mevmax^2 ,

wherevmaxrepresents the maximum kinetic energy of the electron. Therefore

the required velocity is

vmax =

[

2 Tmax

me

] 1 / 2

=

[

(2)

(

6. 408 × 10 −^15

)

9. 1 × 10 −^31

] 1 / 2

=1. 2 × 108 ms−^1.

Synchrotron Radiation

X-ray tubes are not the only means of producing x-rays. In high energy facil-
ities where particles are accelerated in curved paths at relativistic velocities using
magnetic fields, highly intense beams of photons, called synchrotron radiation, are
naturally produced. We saw earlier that when electrons decelerate in a medium
they give rise to conventional x-rays called Bremsstrahlung. On the other hand the
synchrotron radiation is produced when charged particles are accelerated incurved