Cosmic Array

An array of cosmic ray detectors across a landscape that demonstrates in light and sound how cosmic rays are constantly all around us.

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Each detector in the array is designed to produce deferent coloured light and sound depending on the direction of the cosmic ray (muon) passing through it. Observers will witness in real time, how cosmic rays are all around us, as each detector twinkles with sound and light. Further, as cosmic rays arrive in showers of particles, from time to time, these detectors will trigger in unison. The experience something similar to the sights and sounds of life. Flocks of birds, cicadas, or fireflies, where their actions fade in and out from randomness into unison. Cosmic Rays originate from interstellar space, particles thrown off in the catastrophic death of stars. Ever present throughout the entire evolutionary history of life on our planet. This display reinforces our connection with the immense scale, age and complexity of the universe and the importance of science. Maybe to help grow an appreciation of how tiny our planet is, so precious, rare and fragile, something worth protecting.

This project provides an interesting window into the universe and the natural world around us, leaving the observer to form their own connections and conclusions.  Information about Cosmic Rays, what they are, their origins and how to detect them are on my website here: (open source)

I'm working on a number of different design approaches to 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.

Another aim is to setup an IoT wireless network that links each detector, so for example 100 detectors spread across a hectare might be monitored in real time to produce inspiring graphics and music from overall detector activity. Further, each element of the Cosmic Array is a complete cosmic ray (muon) detector and also a radiation (gamma) monitor. So it is not just limited to a pretty light and sound display, it can also be used to measure both cosmic ray flux and local background radiation levels. Allowing the array to collect useful environmental data over a network or the internet.

Recently I completed a real-time demonstration using 16 Detectors in Adelaide for the Splash Adelaide winter festival on the 2nd and 3rd of September 2017.

Each detector in the array produced a bright flash of one of 4 colours (red, green, blue or white). In the same manner, one of 3 musical notes and all 3 notes ( a Chord) together, depending on the trajectory of the muon that passed through two or more Geiger–Müller tubes simultaneously.  A combination of copper radiation shielding and coincidence detection methods were used to filter out local background radiation.

The Splash Adelaide installation was very successful will allot of public interest, questions and discussion about the universe.  The IoT setup was also very successful using Pi Zero W and we were able to stream live data to another computer where it was mapped into music using MAX/MSP software where combined into a beautiful musical soundscape. 

I will also have this array on display along with other detectors I have made at the next Maker Faire Adelaide 2nd November 2017.  Maker Faire Adelaide is the largest Maker Faire in Australia and in the Southern hemisphere. Also the only Maker Faire solely run by volunteers. 

XXLX-7875-G (2).zip

PCB Gerber Files V8

x-zip-compressed - 18.29 kB - 09/05/2017 at 03:59


Cosmic Array V8.pcb

PCB Design using ExspressPCB V8

pcb - 28.10 kB - 07/11/2017 at 12:02


Cosmic Array.pcb

PCB Design using ExspressPCB V7

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
  • 1 × LM2576S-ADJ Step-Down 3A 5-Pin TO-263-6 SMD D²Pak
  • 1 × Voltage Regulator Positive Fixed 5V 1A SMD DPAK-3
  • 3 × Green LED 2.2V SMD 0805

View all 33 components

  • Si Pin Photodiode solid-state detector first draft.

    Robert Hart10/06/2017 at 04:02 0 comments

    I'm currently exploring a new solid-state detector design using Pin Si Photodiodes, this is still a few months away. But will be a feature of a new cosmic ray detector designs to come.   The main issue with using Geiger–Müller tubes and Photomultiplier scintillators as detectors is mostly cost. But also includes limited life and high voltages between 400 to 1600V DC which must also be low noise and regulated. 

    Solid state devices particularly Si Pin Photodiodes are capable of measuring both ionising radiation (Muons) and some added benefits like energy resolution, low voltage, low power, greater longevity and lower cost. But do have issues and compromises such as: more complexity, noise, and a small aperture size.  

    There are some specialist Photodiodes designed specifically for this application, but these are very expensive and difficult to source in small quantities for example:

    • Manufacture First Sensor Part # 5014450 - has visible light filter 
    • Manufacture First Sensor Part # PS100B-7-CERPINE - has visible light filter 
    • Hamamatsu Part # S3590 - no visible light filter

    Here is an example using the First Sensor 5014450 and an old CD V-700 Geiger Counter check source which is radium 226Ra.  Although successful, the detector is expensive (~$50au) and still only has a relatively small aperture compared with a  Geiger–Müller tube, so multiple detectors would be required.

    There are lower cost of-the-shelf Pin Photodiodes such as the BPW34F which have been featured in many DIY radiation detector projects over the years. However, these have an even smaller aperture.  So many will need to be connected together to increase it.  However, they can not be simply wired in parallel due their combined capacitance.   Here is rough layout that I have began experimenting with using JFETs to buffer each photodiode before amplification. 

  • Splash Adelaide 16 Detector Array

    Robert Hart09/06/2017 at 09:26 0 comments

    The Splash Adelaide installation was very successful will allot of public interest and questions.  The IoT setup also went well and we were able to live stream data to another computer where it was mapped into music using MAX/MSP software.  The sounds in the following video include bell sounds from each detector and also the combined musical soundscape generated in MAX/MSP. 

  • Cosmic Array goes Live

    Paul Schulz09/02/2017 at 08:01 0 comments


    Cosmic Array Layout

    Tent for Infrastructure, Visitors and Cosmic Array Information

    See videos: 

  • First build of 16 element array.

    Robert Hart09/01/2017 at 13:25 0 comments

    The last 2 months I have been preparing for my first demonstration project with an installation of an array of 16 detectors in Adelaide Elder Park, South Australia as part of the Winter Splash Adelaide.   It was a lot more work than I expected, but I'm pleased to report it has been successful. It will be installed on the 2/9/2017. More to report soon. Here is a video of the build process from prototype to completed units tested in my back yard.  The sound of the detectors will be recorded at the event soon.

  • SD Cards configured

    Paul Schulz07/30/2017 at 05:41 0 comments

    The software for the detectors has been installed on the SD Cards, and prepared for posting to Robert for installation in the Raspberry Pi Zero's.

    This installation contains new audio files.

    Cosmic Array SD Cards

    Some details

    The OS Image being used is Raspbian Jessie (2017-07-05-raspbian-jessie-lite).

    A Raspberry Pi 3 is used as it provides a wired network interface, as well as a screen and keyboard.

    Once the OS Image has been written to the SD Card (16GB), it is booted with screen and keyboard attached and via the configuration tool (raspi-config), the hostname is set (cosmic-array-*-*), the SSH service is enabled and the Pi is rebooted.

    SSH keys are manually copied to the card using ssh-copy-id.

    An ansible playbook is used to connect to the system via SSH and setup the wireless, additional packages and to checkout the cosmic-array software from GitHub. While this might be slightly overkill for individual cards, these configuration tools will allow all 16 detectors to be modified and updated easily later on. 

    Finally, the 'config/' script is run from the cosmic-array software to setup boot parameters (audio system overlay), programs started on boot and  audio volume settings. This script will probably be included in the ansible setup process in the future.

  • Code now available on GitHub

    Paul Schulz07/28/2017 at 11:04 0 comments

    The code,  data and files required to drive the RaspberryPi Zero has now been made available via GitHub.


    This code is 'feature complete' for the standalone cosmic array sensor. 

    Suggestion, Comments, Branching and Patches welcome. Distributed under GPL v3.

  • Big problem solved with small fix

    Robert Hart07/23/2017 at 11:35 0 comments

    Recently we completed work on Cosmic Array sound and IoT using the new Raspberry Pi Zero W. But the addition of a Raspberry Pi and the audio amplifier caused the detector to trigger more often than it should.   At first, it didn't seem to be an extra load on the 5V regulator. Nor the Geiger-Muller tubes after a check with a radioactive check source and DSO.    

    Then I remembered! I cut back on components to simplified the circuit design and cut costs.  One of the components I removed was a 4V7 Zener diode on the output of the 10pf coupling capacitor connecting the Geiger-Muller tube to the 555 monostable oscillator trigger pin 2.   At the time of the redesign, I forgot the real reason for the Zener just assuming it was there for voltage protection between the high voltage and low voltage sections.   

    The 555 timer acts as both a Schmitt trigger to shape the negative pulse from Geiger-Muller tube to a +5VTTL and increases the pulse width.  Pin 2 of the 555 is the trigger for the monostable oscillator when it detects ground travelling pulse.  So Pin2 is held at the supply rail voltage by a 47k resistor so when the high impedance negative pulse from the Geiger-Muller tube it triggers.  

    The trouble came when both the Raspberry Pi and the audio amplifier where added to the 5V supply rail that supplies the 555 circuits. Although the quiescent state supply rail measured 5V after coincidence is detected, the Pi plays a wave file and then the Audio amplifier causes ripple currents the trigger the other 555 monostable oscillators causing them to trigger randomly resulting in more ripple currents.  

    The solution is to hold pin 2 at 4.7V with a Zener diode and the problem goes away.   The new boards are also designed with a higher current regulator further reducing this effect.

  • Cosmic Array and the Raspberry Pi Zero W

    Robert Hart07/21/2017 at 08:45 0 comments

    To give each element of the Cosmic Array sound and IoT we are using the new Raspberry Pi Zero W

    The Raspberry Pi Zero W doesn't have sound but with the addition of a low pass filter thanks to information on Adafruit Learn Blog this was quite straight forward.

    Amplified by a  5V 3W Class D amplifier based in the PAM8403 which is cheaper to source as a fully assembled PCB than a chip on its own.

    I needed 16  4 x 4 Raspberry Pi Zero W for an Art installation at Splash Adelaide and although there has been a one order per customer limit imposed by the Raspberry Pi Foundation on suppliers. 

    Thanks to wonderful local Hackerspace Adelaide community we have been able to source 16  x Raspberry Pi Zero W for the task. 

  • Final shape of the detectors coming togeter

    Robert Hart07/15/2017 at 00:05 0 comments

    The last few weeks while Paul has been developing the code for the Pi Zero W we'll be using in this build for IoT networking and sound effects. I've been working on the hardware and ordering parts for 16 detectors. As the detectors will be out in the weather they will need to be waterproof and have the ability add other features at a latter stage.

    The unit will be slightly different to this as I've found a supplier of Outdoor UV resistant Acrylic Spheres.

    The spheres I will be using are on order and should arrive in a few days along with the waterproof enclosures both I've been able to source at wholesale.

    Post Top Light Exterior Opal Acrylic Sphere E27 in 20cm Galactic Oriel Lighting. Exterior IP44 spherical opal acrylic post top. Complete with black polycarbonate base to suit 60mm outside diameter post.

    Gasket seals, stainless steel hardware and IP66 rated , Opaque cover: 200(L) x 200(W) x 130(D)mm, ncludes a 1.8mm galvanised chassis for mounting electronics.

  • Raspberry Pi Pinouts

    Paul Schulz07/13/2017 at 00:36 0 comments

    The following are the proposed pinout allocations for the Raspberry Pi (Pi 3 or Pi Zero W) in the project.

     | Description  |    Name |    Mode | Physical | Mode    | Name    | Description  |
     | (Connected)  |         |         |          |         |         | (Connected)  |            
     |              |    3.3v |    3.3v |  1 || 2  | 5v      | 5v      | +5v Supply   |
     |              |   SDA.1 |       - |  3 || 4  | 5v      | 5v      | +5v Supply   |
     |              |   SCL.1 |       - |  5 || 6  | GND     | 0v      | Gnd Supply   |
     |              | GPIO. 7 |       - |  7 || 8  | -       | TxD     |              |
     | Logic Gnd    |      0v |     GND |  9 || 10 | -       | RxD     |              |
     | Chan. Red    | GPIO. 0 |  IN/TRI | 11 || 12 | IN/TRI  | GPIO. 1 | Chan. Green  |
     | Chan. Blue   | GPIO. 2 |  IN/TRI | 13 || 14 | GND     | 0v      |              |
     |              | GPIO. 3 |       - | 15 || 16 | -       | GPIO. 4 |              |
     |              |    3.3v |    3.3v | 17 || 18 | -       | GPIO. 5 |              |
     |              |    MOSI |       - | 19 || 20 | GND     | 0v      |              |
     |              |    MISO |       - | 21 || 22 | -       | GPIO. 6 |              |
     |              |    SCLK |       - | 23 || 24 | -       | CE0     |              |
     |              |      0v |     GND | 25 || 26 | -       | CE1     |              |
     |              |   SDA.0 |       - | 27 || 28 | -       | SCL.0   |              |
     |              | GPIO.21 |       - | 29 || 30 | GND     | 0v      |              |
     |              | GPIO.22 |       - | 31 || 32 | OUT/PWM | GPIO.26 | Audio Out(L) |
     | Audio Out(R) | GPIO.23 | OUT/PWM | 33 || 34 | GND     | 0v      | Audio Gnd?   |
     |              | GPIO.24 |       - | 35 || 36 | -       | GPIO.27 |              |
     |              | GPIO.25 |       - | 37 || 38 | -       | GPIO.28 |              |
     |              |      0v |     GND | 39 || 40 | -       | GPIO.29 |              |
     | Description  |   Name  |    Mode | Physical | Mode    | Name    | Description  |

View all 30 project logs

  • 1
    Considerations for building a cosmic ray detector

    Cosmic Rays are created high in the earth's atmosphere (~30km) and the resulting shower of subatomic particles are what we can detect at sea level.  These particles interact with atmosphere, decay or are difficult to detect, but the muon the heavier cousin of the electron can be detected as it has a charge and can ionise matter as it passes through.   Consequently it can be detected using any ionising radiation detector such as: Cloud chambersElectroscopeGeiger CountersSpark Chambers, Resistive Plate Chambers, and materials called Scintillators which give off light when an ionizing particle passes through them.

    A muon  has a measured mean lifetime of 2.2 microseconds and should only be able to travel a distance of 660 metres even at near the speed of light and so should not be capable of reaching sea level. However, Einstein’s theory of relativity tells us that time ticks slowly when moving at speeds close to that of light. Whilst the mean lifetime of the muon at rest is only a few microseconds it moves at near the speed of light and so its lifetime is increased by a factor of ten or more giving them plenty of time to reach the ground and be detected.

    The problem of using a radiation detector for a cosmic ray observations, is that there is larger amounts of terrestrial radiation as much 73% of background radiation is Alpha, Beta, and Gamma from the natural decay of matter. Although in small quantities it is sufficient to make it difficult to discriminate between a terrestrial or cosmic sources.

    Consequently, at least two detectors are needed placed one above the other, feed into electronics that can monitor coincidence between the two detectors quickly thus, filtering out most terrestrial radiation.

    Cosmic particles travel at nearly the speed of light and so do not ionise very efficiently and hence can travel through matter very easily passing through metal shielding and both detectors without effort, whereas the terrestrial radiation may not. Consequently anything detected in both detectors simultaneously is more likely to be a cosmic event than terrestrial.

    Well almost simultaneously, if a muon is travelling at 0.998c and the detectors where spaced 5cm apart the actual flight time of a muon would be just 0.16ns. However as the detector and electronics response and delay times would be much slower than this, we can say in "real-life" terms it is simultaneous.

    The main idea of coincidence detection in signal processing is that if a detector detects a signal pulse in the midst of random noise pulses inherent in the detector, there is a certain probability, p, that the detected pulse is actually a noise pulse. But if two detectors detect the signal pulse simultaneously, the probability that it is a noise pulse in the detectors is p2. Suppose p = 0.1. Then p2 = 0.01. Thus the chance of a false detection is reduced by the use of coincidence detection.

  • 2
    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.

    History is full of examples of physicists using Geiger–Müller tubes for cosmic ray observations up to the 80s. Geiger Tube Telescopes (GTT) were used by NASA including many Pioneer spacecraft missions and others. One most notable user was 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.

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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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