Cosmic Array

Here is the first simple proof of concept idea using Geiger–Müller Tubes (GMT) and coincidence detection using logic gates which worked first time.

Simulation of how I imagined this circuit might work.

Actual first strip board prototype

First live test of prototype

his detector design is an experiment in using a summing amplifier for measuring coincidence between multiple ionizing radiation detectors. In this example four Geiger–Müller tubes. The output would be used to drive different colours and sounds based on the voltage level of each pulse. It would also display background radiation as a specific colour/sound which would be ~1/4V pulse. Where a muon strike (cosmic ray) being either ~1/2V ~3/4V and ~1V.

Note the pulse height clearly increasing when the tubes are oriented from vertical to horizontal. This is a result of an ionizing particle traversing through more than one GMT originating from the sky.

Highly simplified GMT detector

To get the price of each cosmic ray detector in the array down, I am currently developing a solid state detector using a matrix of low cost BPW34F SiPin Photodiodes, without the use of a scintillation panel. I have already used these diodes in other experiments and although on there own there are many limitations in it maybe possible to overcome them in a larger matrix.
https://hackaday.io/project/1749-solid-state-ionising-radiation-detector

The aim of this design will be to use layers of individually amplified photodiodes in a matrix where each matrix element is strongly pulse shaped. Coincidence detection is then measured between layers to identify relative location of where a Muon has passed through to produce each a colour and musical note output. This is a similar, but not identical method to the on used in my Cosmic Ray Hodoscope detector using GM tubes, but on a much smaller scale:
https://hackaday.io/project/1700-cosmic-ray-muon-81-9x9-pixel-hodoscope

The aim of this project is to deploy 16 individual cosmic ray detectors on the Elder Park foreshore in Adelaide. This is a part of the Splash Adelaide 2017 Winter Festival and is built in collaboration with a group of artist-musicians called Sacred Resonance.

Proposed Location on the Elder Park foreshore

When the public come to visit this installation, they will experience how cosmic rays are all around us and arrive in showers of particles. Each detector will seem to randomly twinkle with colours and sounds that are triggered by cosmic rays. The experience will be not unlike walking through a maze of colourful wind chimes.

However, as cosmic rays arrive in showers of particles, some of these detectors will trigger in unison and others randomly. A similar experience to what can be witnessed in nature like the sounds of Cicadas or the flashing light of Fireflies, where both sound and light fade in and out from randomness into unison.

Cosmic Rays have been present throughout the entire evolutionary history of life on our planet and so this display reinforces our connection with the universe and the importance of science and understanding the natural world.

However, the project has no agenda other than the first of what I hope are thought-provoking art/science installations. Which will provide an interesting window into the universe and the natural world around us, leaving the observer to form their own connections and conclusions.

Technical
Each detector in the array will produce a bright flash of one of 4 colours (red, green, blue or white). In the same manner, one of 3 musical notes ( e.g. C, F, G or other notes) or all 3 notes together depending on the direction and angle of an ionising particle called a muon passes through two or more Geiger–Müller tubes simultaneously. Music samples are currently being developed by Darren Curits a musician at Sacred Resonance.

This design will use 3 Geiger–Müller tubes in each and gate logic for coincidence detection as used in previous prototypes, as these have worked very reliably.

Working demonstration prototype.

The detectors aesthetics, however, have yet to be finalised it may either be enclosed in a type of Sphere on the ground, bollard lamp post, something that hangs on a pole, tripod or put directly into the ground like a paving block.

A rough demonstration of light and sound using a current prototype

Overview block diagram of operation

Circuit diagram of detector

PCB Layout 96.5mm X 63.5mm

The Splash Adelaide project will be a good proof-of-concept project in real life. Although I'd like to deploy many more detectors, the limited space available I have for this project I can only practically deploy a grid of 16 detectors. I've finalised the detector and power board PCB design and have ordered some prototype PCBs for testing. Other parts include various enclosures, RGB LED Strips, sound trigger modules and other bits and pieces.

Each element of the Cosmic Array is essentially a complete cosmic ray (muon) detector and radiation (gamma) monitor. So it can not only be used in a light and sound display but also be used to measure both cosmic ray flux and background radiation.

So it made sense to design the PCB so this information can be accessed by a suitable IoT device. Where information can accessed or transferred over a network or the Internet. As this detector doesn't have any microprocessor, adding the Adafruit Feather HUZZAH with ESP8266 WiFi looks like the ideal companion.

Raw count data without coincidence detection as 5V TTL pulses is accessible via J1 on the PCB and can be easily dropped to the 3.3V input level of the Adafruit Feather using resistors.

PCB Layout 96.5mm X 63.5mm

Different IoT devices and code are currently being explored by a new team member to this project Paul Schulz who is a strong supporter of open source software community and was a winner in the 2016 Adelaide IoT Hackathon.

Three prototype PCBs arrived today and they look great, but may to adjust some whole sizes on the production run. Finally I can start building, we'll see how the these turn out populated.