X-rays (X-radiation) are shorter in the wavelength ultraviolet and longer in wavelength than gamma rays.
In 1895, the German physicist Wilhelm Röntgen (1845-1923) noticed that there were unknown rays when he was working on his lab with a cathode radiation tube. Wilhelm Röntgen was awarded the first Nobel prize in physics in 1901 for discovering x-rays.
In 1912, the German physicist M. von Laue (1879-1960) discovered that the X-rays can be diffracted by crystals. He was awarded Nobel prize for his discovery in 1914.
W. H. Bragg (1862-1942) and his son W. L. Bragg (1890-1971), the British physicists determined the structure of crystals using the X-ray. They were awarded the Nobel prize in physics in the year 1915.
In the year 1917, C. G. Barkla (1877-1944) the British physicist won Nobel prize in physics, due to his discovery of the characteristic X-ray radiation of the elements.
Kai M. Siegbahn (1886-1978) a Swedish physicist, discovered the X-ray spectroscopy in the year 1923. In the year 1924, he was awarded Nobel prize in physics for his discovery.
In the year 1927, the Noble prize in physics was awarded to Arthur H. Compton (1892-1962) the American physicist, he clarified that the X-rays scattered while he was making experiments on electrons.