Detecting Radiation Oui! It is Friday apres-midi! Time for a bottle du vin avec ma petit fille. Oi Vay! The lab is une grande mess. Je will sweep tout la merde into a drawer! Voila ! Clean! Parfait!

Detecting Radiation Becquerel's photographic plate, fogged by exposure to radiation from a uranium salt. The shadow of a metal Maltese Cross placed between the plate and the uranium salt is clearly visible.

Electroscope : a static electricity detector The leaves repel each other, since they have the same charge. Over time, as invisible charged particles zip through the electroscope, they’ll neutralize some of the positive charge, and the leaves will relax.

Victor Hess carried an electroscope aloft many times between 1911 and He expected that it would be less affected by the Earth’s radioactivity at higher altitudes. But NO! Radiation was coming from beyond the Earth, also. Nobel Prize! Ding!

Cloud Chambers & Bubble Chambers rely on PHASE CHANGES caused by passing unseen particles…

A Geiger counter is a metal case filled with a certain type of gas. Inside the metal case is a positively charged wire with just under the voltage required to ionize the gas within the container. When a charged particle enters through a thin glass panel at one end of the counter, it ionizes the particles of gas within the chamber. These particles are attracted towards the positively charged wire. As they accelerate towards the wire, they ionize additional particles. As the particles strike the wire, they create a voltage pulse which is amplified and sent to an electric counter. These pulses can also be sent to a loudspeaker, which causes each pulse to be heard as a “click” sound. Cloud Chamber

Bubble Chamber….

A Geiger counter is a metal case filled with a certain type of gas. Inside the metal case is a positively charged wire with just under the voltage required to ionize the gas within the container. When a charged particle enters through a thin glass panel at one end of the counter, it ionizes the particles of gas within the chamber. These particles are attracted towards the positively charged wire. As they accelerate towards the wire, they ionize additional particles. As the particles strike the wire, they create a voltage pulse which is amplified and sent to an electric counter. These pulses can also be sent to a loudspeaker, which causes each pulse to be heard as a “click” sound. Geiger Counter

Most silicon particle detectors work, by doping narrow (usually around 100 micrometers wide) strips of silicon to make them into diodes. As charged particles pass through these strips, they cause small ionization currents which can be detected and measured. Arranging thousands of these detectors around a collision point in a particle accelerator can give an accurate picture of what paths particles take. Silicon detectors have a much higher resolution in tracking charged particles than older technologies such as cloud chambers or wire chambers. The drawback is that silicon detectors are much more expensive than these older technologies and require sophisticated cooling to reduce leakage currents (noise source) as well as suffer degradation over time from radiation.

Photomultiplier tubes (photomultipliers or PMTs for short), are extremely sensitive detectors of light in the ultraviolet, visible, and near infrared ranges of the E-M spectrum. These detectors multiply the current produced by incident light by as much as 100 million times in multiple stages, enabling individual photons to be detected when the incident flux of light is very low. Unlike most vacuum tubes, they are not obsolete.