Is it true that without the discovery of the vacuum we would not have discovered xrays?

Like… a vacuum cleaner, or the “vacuum of space?”

I mean creating a vacuum on earth.

I couldn’t think of the scientific explanation (or how to word it at least)... sooo I did you one better, from wikipedia

Man-made X-rays are generated by an X-ray tube, a vacuum tube that uses a high voltage to accelerate the electrons released by a hot cathode to a high velocity. The high velocity electrons collide with a metal target, the anode, creating the X-rays.

“In 1895 Wilhelm Conrad Roentgen carried out research on the phenomenon of cathode rays. By accident he put a piece of cardboard covered with fluorescent mineral near the experimental set. The scientist noticed that it started to glow in the dark when the source of cathode rays was turned on. Roentgen immediately started an experiment aimed at investigation of the phenomenon.
He discovered that if vacuum tube, used for experiments with cathode rays, was covered tightly with thin, black cardboard and placed in a darkened room, bright glow was observed during each discharge on a screen covered with fluorescent barium platinum cyanide (placed near the device). It did not matter which side (the one covered with the mineral or the other one) of the screen faced the device. Fluorescence occurred even when the screen was placed two meters from the vacuum tube.
He assumed that the fluorescence must have been caused by an agent which could infiltrate from within the vacuum tube through dark cardboard (impermeable to visible or ultraviolet radiation) to the outside of the set. In subsequent experiments the scientist showed that this agent (which he called X rays) could penetrate through various different bodies to a different extend (the level of transparency of a given body was described by Roentgen in terms of the ratio of the brightness of the fluorescing screen placed behind the body to the brightness of the uncovered screen). For example paper and tin foil have a high transparency factor. It is slightly less for wood. Even lesser for aluminium. Thin plates of copper, silver, gold or platinum are transparent (but not thick plates). Compounds containing additives of lead (for example flint glass) are much less transparent. Layers of lead are virtually non-transparent.
The scientist discovered that human body was also transparent to X rays – Roentgen put his hand between the vacuum tube and the screen and observed dark shadows of bones against a slightly shaded outline of his hand. ”

Source

Rontgen was vacuuming one day, lost his balance and fell down the steps. The doctors were just going to put him in a body cast to be safe, but before they could offer this vague solution, he discovered x-rays and they were able to use them to diagnose him correctly. So, yes, without the vacuum (and the discovery of it), we would not have discovered x-rays…

Yes, it is true. While x-rays can be produced without a vacuum, Roentgen was investigating cathode rays when he discovered x-rays. All x-ray generators use a vacuum tube, because otherwise only a few electrons would reach the discharge energy required to produce x-rays thanks to collisions with the atoms in the air.

Nearly all science is based on the prior work of others. As Isaac Newton wrote, “If I have seen further it is by standing on the shoulders of giants”