x射線 同伽瑪射射的分別

Some body regards X-rays as low energy gamma rays(γ rays). There is no discrete boundaries between the two. But this is form of classification is not always true.

Some people use the production mechanism to classify the two kinds of rays, like those produced from rapid decceleration of charged particles are termed X-rays, as contrast to those from natural decay of radioactive substances.

For example, diagnosticl X-ray machines for medical use produce X-rays of energy from about 50 keV to 120 keV, but the radio-isotope Americium-241 (this isotope is widely used in smoke detectors) emits gamma rays of energy 60 keV.

Therapeutic machines in the treatment of cancer produce hard X-rays as high as 15 MeV, but most radioisotopes produce gamma rays between 100 keV to 1 MeV (e.g. Caesium-137 produces gamma rays of 660 keV, and Cobalt-60 produces gamma rays of 1.3 MeV, they are much lower than the X-rays produced in cancer treatment machines).

Therefore, it can only be said that in general, photons coming from the nuclides are termed as gamma rays, whereas others, especially those produced by machines that are irrespective of energy, are termed as X-rays.

quantization of EM field = photon:

hamiltonian = sum_k [w(a'a + 1/2)]
dispersion relation w = k x light speed


quantization of lattice vibration in solid= phonon:

hamiltonian = sum_k [w(c'c + 1/2)]
dispersion relation w = 4K/M sin(ka)

伽瑪射線同 X光同樣是電磁波，兩者分別在於不同的產生方法。
X光由激發電子產生而伽瑪射線是激發原子核產生。

伽瑪射線頻率高（但X光與低能量伽瑪射線的頻譜重疊），固能量及穿透力也大些。從量子學來講，伽瑪射線的能量在所有光子中是最高的，達100KeV。

gamma 是希臘字母 γ