Author: haroonkhan

Our CRTs require a beam of electrons, which we produce using the assembly shown in Figure 41. Electrons are stripped off the cathode by a process known as glow discharge between an aluminum cathode rod and a hollow anode. The electron gun is built inside an Ace-Thred #11 connector (Ace catalog number 7644-10). The cathode is a 3/8-in. aluminum…

Electron beams in a good vacuum are invisible, but a screen coated with a material that fluoresces when hit by electrons can be used to make the beam visible. These fluorescent materials are called phosphors, and are used most commonly in cathode-ray oscilloscope and TV screens to produce an image by steering an electron beam inside…

Making vacuum tubes from scratch is almost a lost art. It involves plenty of practice in technical glassblowing, as well as an understanding of materials and vacuum techniques. However, vacuum tubes that operate at relatively high pressures and require continuous pumping are easy to build by cobbling together glass tubes, copper piping, and rubber corks.…

We will also require us to use very high voltages—well in excess of the 2,000 V that can be obtained from the power supplies we built to power the PMT probe. Fortunately, precise regulation at these voltages is not needed, so a high-voltage power supply that can produce over 100,000 V is easy to build. Figure…

Simple mechanical pressure gauges don’t usually work at pressures below 10 Torr, so we need a different way of measuring pressure in our vacuum systems. We use the most inexpensive pressure sensor that works at these levels, which is the T/C gauge. It operates by measuring the thermal conductivity of the gas inside the chamber. As…

We will conduct our experiments in the range of 10 Torr to 10 mTorr, which is easy to achieve using a low-cost, mechanical vacuum pump. Very good results have been obtained by amateur experimenters and educators using vacuum pumps made for servicing air conditioning and refrigeration units. These vacuum pumps are not part of the…

We will deal with the production and detection of subatomic particles, such as electrons and nuclei. As these interact with matter, including air, many of the experiments need to be carried out inside glass tubes out of which the air has been pumped. The normal atmospheric pressure at sea level is right around 1.0 atmosphere,…

Although physicists felt comfortable in the late 1800s with their capabilities to describe the macroscopic world, many questions remained unanswered. Lord Kelvin’s lecture on the “Nineteenth-Century Clouds over the Dynamical Theory of Heat and Light,” referred to two specific problems that interested him. Namely, he discussed the lack of physical theory to explain the speed…