Cosmic Array

An array of individual cosmic ray detectors distributed across a landscape to display how cosmic rays arrive as showers of muons.

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The aim of this detector project is to deploy many detectors across a park or landscape. So that an observer from a distance or walking amongst them 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.

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

More information about what cosmic rays really are, is available here.

I now receive seed funding from Hackaday for every like, if you want to help fund this project, click the like link above.

I'm working on a number of different design approaches for this project as it will need to be more cost effective if I was to build a larger installation of 100 or more detectors. The detectors in the array may be enclosed in a type of bollard lamp post, sphere, something that hangs on a tree or tripod or is put in the ground like a paving block.

Future prototypes and installations may include a software, pulse summing and solid-state detectors. More details about this project will be added in the project logs below.

Another aim is also to setup a IoT wireless network linking each detector, so for example 100 detectors spread across a hectare might be monitored live to produce a histogram of activity. Further 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 local background radiation. So the design will also include a suitable IoT device so information can be accessed or transferred over a network or the internet.

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.

I'm currently building a demonstration project in Adelaide for the Splash Adelaide winter festival in August, so any funds will help greatly. Information about this build, will be posted here and on my website about Cosmic Rays.

Note: Geiger–Müller Tubes
I've had comments regarding the validity of using Geiger–Müller Tubes for a cosmic ray (muon) detector. Pointing out that Photomultipliers and scintillation panels are best, and yes the are far more effective. However, they are also expensive, whereas Geiger–Müller tubes are relatively cheap and easily available to purchase.

Although I'm currently working on a solid-state detector there are a few issues yet to overcome, so this is still a few months away.

History is full of examples of physicists using Geiger–Müller tubes, most notably Bruno Benedetto Rossi a famous Italian experimental physicist who made major contributions to particle physics and the study of cosmic rays. At the age of 24, he fabricated his own Cosmic Ray detector using Geiger–Müller tubes and then went on to invent the first practical electronic coincident circuit.

Cosmic Array.pcb

PCB Design using ExspressPCB

pcb - 29.77 kB - 06/10/2017 at 23:05


  • 3 × Resistor 10M Ohm 0.25W, 1/4W SMD 1206 HV
  • 3 × Capacitor 10pF ±5% 1kV Ceramic NP0 SMD 1206
  • 3 × Capacitors 1µF 450V Aluminum 2.5mm Radia
  • 3 × Resistor 47.5k Ohm ±1% 0.25W SMD 0805
  • 3 × Resistor 560k Ohm ±1% 0.125W SMD 0805

View all 30 components

  • Mechanical Spec for Raspberry Pi Zero

    Paul Schulza day ago 0 comments

    See: Introducing the Raspberry Pi Zero


    • 4x M2.5 mounting holes
      • Centres - width 58mm, depth 22mm
      • Holes drilled to 2.75 +/- 0.05mm


    • Header 40 pin
      • Centred between two mounting holes.
      • Centre at 29mm from mounting hole.

  • Changes to PCB Design

    Robert Hart2 days ago 0 comments

    Very pleased the first prototypes worked straight off , without modification. The new board design includes a 2A 5V supply for running external devices like a Raspberry Pi, Pad spacing changes for some components and the ability to add terminal blocks or connectors for wiring. Including an extra output for coincidence of three GMT.

  • Getting data input on RasperryPi.

    Paul Schulz2 days ago 0 comments

    It is possible to read the GPIO (General Purpose Input Output) pins on the Raspberry Pi to record events from the Cosmic Ray Detectors.

    There is a library (Wiring Pi) which makes this access to the GPIO Pins really easy. Included in the software is a utility gpio which provides this functionality from the command line.

    $ gpio readall
     +-----+-----+---------+------+---+---Pi 3---+---+------+---------+-----+-----+
     | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
     |     |     |    3.3v |      |   |  1 || 2  |   |      | 5v      |     |     |
     |   2 |   8 |   SDA.1 |   IN | 1 |  3 || 4  |   |      | 5v      |     |     |
     |   3 |   9 |   SCL.1 |   IN | 1 |  5 || 6  |   |      | 0v      |     |     |
     |   4 |   7 | GPIO. 7 |   IN | 1 |  7 || 8  | 0 | IN   | TxD     | 15  | 14  |
     |     |     |      0v |      |   |  9 || 10 | 1 | IN   | RxD     | 16  | 15  |
     |  17 |   0 | GPIO. 0 |   IN | 0 | 11 || 12 | 0 | IN   | GPIO. 1 | 1   | 18  |
     |  27 |   2 | GPIO. 2 |   IN | 0 | 13 || 14 |   |      | 0v      |     |     |
     |  22 |   3 | GPIO. 3 |   IN | 0 | 15 || 16 | 0 | IN   | GPIO. 4 | 4   | 23  |
     |     |     |    3.3v |      |   | 17 || 18 | 0 | IN   | GPIO. 5 | 5   | 24  |
     |  10 |  12 |    MOSI |   IN | 0 | 19 || 20 |   |      | 0v      |     |     |
     |   9 |  13 |    MISO |   IN | 0 | 21 || 22 | 0 | IN   | GPIO. 6 | 6   | 25  |
     |  11 |  14 |    SCLK |   IN | 0 | 23 || 24 | 1 | IN   | CE0     | 10  | 8   |
     |     |     |      0v |      |   | 25 || 26 | 1 | IN   | CE1     | 11  | 7   |
     |   0 |  30 |   SDA.0 |   IN | 1 | 27 || 28 | 1 | IN   | SCL.0   | 31  | 1   |
     |   5 |  21 | GPIO.21 |   IN | 1 | 29 || 30 |   |      | 0v      |     |     |
     |   6 |  22 | GPIO.22 |   IN | 1 | 31 || 32 | 0 | IN   | GPIO.26 | 26  | 12  |
     |  13 |  23 | GPIO.23 |   IN | 0 | 33 || 34 |   |      | 0v      |     |     |
     |  19 |  24 | GPIO.24 |   IN | 0 | 35 || 36 | 0 | IN   | GPIO.27 | 27  | 16  |
     |  26 |  25 | GPIO.25 |   IN | 0 | 37 || 38 | 0 | IN   | GPIO.28 | 28  | 20  |
     |     |     |      0v |      |   | 39 || 40 | 0 | IN   | GPIO.29 | 29  | 21  |
     | BCM | wPi |   Name  | Mode | V | Physical | V | Mode | Name    | wPi | BCM |
     +-----+-----+---------+------+---+---Pi 3---+---+------+---------+-----+-----+

    The values shown in this table correspond to the values detected for floating inputs.

    The following video shows how the grounding of the SDA.1 /wPi pin 8 (second down on left) causes this pin to display a state of '0' and '1' (alternating connect and disconnect). (There is also some noise seen on the TxD pin.)

    The laptop displaying the output is connected to the Pi via Wifi and SSH.

  • First test of Prototype PCB V7 works well.

    Robert Hart2 days ago 0 comments

    Just completed populating 3 prototype PCBs and have begun wiring and testing. Very pleased they work as expected. The GM Tubes here are the classic SBM-20 but in the installation I'll be using a different tube.

  • An IoT Device...

    Paul Schulz3 days ago 0 comments


    The intention was always to network the individual detectors together to allow for real-time (or near real-time) collection of event data. Several technologies and solutions were investigated. This log entry describes these investigations.

    Configurations considered ranged from using a networking module attached to a microprocessor to a higher powered System on a Chip (SoC).

    The main detector boards send raw output as voltage pulses (width?) on three wires which can be read directly by a connected controller. The initial design had these pulses being the output from the coincident circuits and so represented the red, green, blue (and white) channels. These pulses with a suitable electronic drivers could be used to power solenoids for operating mechanical noisemakers, corresponding to the detected events.

    The networking technologies discussed:

    • LoRaWAN networking - Adelaide has a growing IoT network encouraging the growth of Open Data. Still growing.
    • Zigbee - This might have been useful. Ultra low power modes are available, but modules are more expensive and need to be placed
    • Bluetooth - Range might have been an issue across the area required.
    • WiFi - Well established and understood technology, cheap and available.

    Wifi modules considered:

    • ESP8266 Module - 3.3V module which, in default configuration, uses AT text commands over a serial connection.

    Microprocessors (and microprocessor boards) considered:

    • Arduino UNO R3, by keyestudio. This uses the ATMEL Mega16u2 for handling the USB-to-Serial interface. It is possible to reprogram this chip so that the Arduino board can be made to look like another device on the USB interface, like a keyboard or mouse. We probably won’t use this for this project, but together with the ESP8266 Module this might provide a very easy mechanism to log data from the network.

    "System on a Chip"s that were considered:

    • Raspberry Pi 3 with Wifi - Very useful as a development environment.
    • Raspberry Pi Zero W (with Wireless) - Cheaper than the Pi3 and still very capable of doing what we need.
    • Adafruit Feather HUZZAH with ESP8266 WiFi - Looks very useful and cheap. It's programmable via Arduino IDE and comes with battery management for a final (polished) detector system.

    The price of units was also a consideration as it is hoped that over 100 detectors could be build for a future system spread over the area. Other constraints considered:

    • Constrained build time - the solution is build from well known technology to minimise any required development work (+Wifi, -Other networking options)
    • Deployment should be as simple as possible.
    • What is on hand and/or easy to acquire?

    The initial solution will definitely be a hack. A second iteration would be expected to see system changes.


    For each detector:

    • Raspberry Pi Zero with Raspbian Operating System.
    • Connected via GPIO pins to detector for events.
    • Connected to Wifi access point, pre-configured with network Id (say ‘cosmic-ray’) and password.
    • Sends event data to central server.

    For the Access point router and network server:

    • Powered by 12V battery
    • Allocates IP addresses via DHCP (may be fixed to assist with identifying deployed units)
    • Deployed with longer range, higher gain omni-directional antenna (flat antenna pattern).

    For the network server

    • During development, the server could be a laptop.
    • For deployment, a laptop could be used, together with a tethered phone for transmitting data to other consumers on the internet.

    Networking and Data Protocol

    • Detector client software triggers on a detection event and sends a UDP packet to the server, which records the data.

    Other useful ideas and thoughts:

    • Add a back channel to allow the controller to control/set the outputs on the detector. Useful for testing and deployment. The system could then also be used as a distributed display, suitable for placing in building windows etc.
    • Raspberry Pis can be booted from a single image...
    Read more »

  • Building prototypes for testing

    Robert Hart06/18/2017 at 12:05 2 comments

    Currently building 3 prototypes for testing and develop enclosures, lighting and sound. Found only a few hole size and spacing issues on the PCBs which I can fix in the next run.

  • Version 7 Prototypes Begin

    Robert Hart06/14/2017 at 10:49 0 comments

    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.

  • IoT and background radiation monitoring.

    Robert Hart06/10/2017 at 07:21 0 comments

    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.

  • Ordering Parts for Splash Adelaide project

    Robert Hart06/03/2017 at 23:18 0 comments

    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.

  • IoT Concept Model for larger installation

    Robert Hart05/22/2017 at 07:40 0 comments

View all 16 project logs

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Robert Hart wrote 06/10/2017 at 01:56 point

Hi followers, I now receive seed funding for this project for every click of the like button.

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Andrew Bolin wrote 05/08/2017 at 23:22 point

Congratulations on being one of the winners of the concept round. 

Good to see another Aussie on here! If the project goes well, maybe you could consider bringing it up to Sydney for Vivid.

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Robert Hart wrote 05/09/2017 at 07:28 point

Hi Andrew, Thank you, I'm currently building a small array of 20 detectors for the Splash Adelaide Winter festival. Btw I'm originally from Sydney, moved to Adelaide 20 years ago.

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DontStalkME wrote 04/05/2017 at 08:43 point

Could you make it cheaper by using tin-can ion detectors? Or make your own GM tubes? You could get funding by pre-selling the boxes on kickstarter. Then after you get some images you can ship them out. This assumes you are not wanting a permanent installation.

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Robert Hart wrote 04/08/2017 at 22:15 point

Hi DontStalkME, An Ion detector can indeed detect Muons, in fact the very early discoverers of cosmic rays used such detectors. However, they are slow, unstable and are effected by other environmental factors like humidity.  Nevertheless I have developed a solid state detector using a matrix of low cost SiPIN photodiodes. Just haven't published this yet as it is a rat nest gamma detector and not yet in a coincidence detector configeration. 

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biemster wrote 10/23/2016 at 19:03 point

Very nice idea! I've worked for cosmic shower detectors in Holland (HiSparc) and Argentina (Auger). The shower front on earth' surface is usually multiple kilometers wide, what inter-detector spacing are you planning to use?

For HV generation you could consider PWM and a boost converter, something like I did here #ESP8266 Geiger counter. The circuit could easily be adapted to count events on the three tubes on different GPIO's of the uC. That would simplify the schematic quite a bit, and if you choose for the ESP as well you can easily network them together too.

In addition to my inter-detector spacing question, how many stations are you planning?

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Robert Hart wrote 10/24/2016 at 06:31 point

Hi Biemster,  Thank you! This in the very early stages of development, mostly a proof of concept. I've built many cosmic ray detectors, Geiger counters and PMT counters, just for lolz.  I have developed a good power supply but I fear it's a little over the top for this project and if I want to build a 100 lets say it would be difficult to fund as a hobby project.  So yes I've been thinking about a boost switch-mode approach.   I'm also considering a solid-state detector as well, which I've also been working on.  For this project I might just build a few using GM tubes as demonstration pieces and then maybe go for some crowd funding.  3 ideas I have for an installation would be 1) bollard lamp post in a city parkland 2) block paving bricks 3) across a remote desert landscape below a hill.  these detectors would be placed a few metres apart and most likely 100 or more.  

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