Arduino does Hard Science

We don’t know why [stoppi71] needs to do gamma spectroscopy. We only know that he has made one, including a high-voltage power supply, a photomultiplier tube, and–what else–an Arduino. You also need a scintillation crystal to convert the gamma rays to visible light for the tube to pick up.

He started out using an open source multichannel analyzer (MCA) called Theremino. This connects through a sound card and runs on a PC. However, he wanted to roll his own and did so with some simple circuitry and an Arduino.

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A touch screen Geiger counter without a Geiger tube


We’re assuming [Toumal] was desperately bored one day, because in the depths of the Internet he found some really cool components to build a solid state Geiger counter.

The Arduino and touchscreen are rather standard fare [Toumal] picked up on eBay for about $30. What really sets this project apart from all the other geiger counter builds we’ve seen is the solid state geiger counter [Toumal] used. This device uses a specially-made photodiode made by First Sensor to detect gamma emissions from 5 to 1000 keV.

[Toumal] put all the software for his Arduino touch screen radiation detector up on github. To be honest, we’re really impressed with the rad sensor [Toumal] used for this project, so if you ever decide to pick one of those up, he’s got your back with an Arduino library for it.

A very tiny gamma ray detector


When you think of a radiation detector, you’re probably thinking of a Geiger tube and its high voltage circuitry. That isn’t the only way to measure gamma radiation, though, and [Alan] has a great circuit to measure even relatively weak radiation sources. It uses a very small photodiode, and draws so little power it’s perfect for projects with the smallest power budgets.

The detector circuit uses a miniature solar cell and a JFET wired up in a small brass tube to block most of the light and to offer some EM shielding. This, in turn, is attached to a small amplifier circuit with a LED, Piezo clicker, and in [Alan]’s case a small counter module. The photodiode is actually sensitive enough to detect the small amounts of gamma radiation produced from a smoke alarm americium source, and also registers [Alan]’s other more powerful radioactive sources.

The circuit only draws about 1mA, but [Alan] says he can probably get that down to a few micoAmps. A perfect radiation sensor for lightweight and low power applications, and gives us the inspiration to put a high altitude balloon project together.

Gamma-ray scintillation probe in a paint can

The [Prutchi] family sounds pretty cool. [David], the father, is a well educated engineer, has 70 patents, and has written two books. On his off time, he has a passion for making experimental physics accessible to the average Joe. His daughter [Shanni] is a high school student who co-authored one of those same books, and helps conduct research in the fields of Radio-Astronomy and Quantum Physics. Together, they came up with an affordable, yet very sensitive, gamma-ray scintillation probe for their customized Civil Defense V-700 radiation survey meter. Sweet.

They decided to use parts that were low cost and readily available so others could easily follow in their footsteps. A Philips XP5312/SN photomultiplier tube (PMT) and scintillation plastic are the main components.  The enclosure for the probe is a standard paint can, lined with polyurethane foam inserts to help protect the assembly and hold everything in place.

[David] says that since the probe is very portable and has a high level of sensitivity, it is an ideal candidate for radioactive mineral surveying and scouting miscellaneous gamma-ray sources. They documented the whole process and have compiled a handy PDF file for those who are interested in creating their own.