Hardware Hacking

This new project came about as a way of problem solving issues I've been having with the 20 Tube Detector.

So the aim this project is try and visualise different cosmic ray strikes using a lessor number of tubes and achieve a wider pulse output that is already pre-processed for coincidence that an I/O card like the Arduino or other devices can easily read.

^{Please note, this group of projects are not intended to achieve any significant scientific outcome, other than creating interesting objects that demonstrate the natural radiation and cosmic rays that are all around us and pass through us everyday, but that most people are unaware of their existence.}

How will it work?
Geiger–Müller Tubes (GMT) are arranged in row of four GMT side by side and then another row of three below them at right-angles to form the X and Y coordinates. When a Cosmic Ray passes through the two layers and the coincidence measured the output can be registered in one of 16 sectors (or pixels).  Radiation shielding is used between the two layers to reduce the probability of false coincidence detections caused from terrestrial background radiation.

Much of the circuit has been refined in other experiments, so running from left to right the first section detects the  negative travelling pulse from the six GMT's, where it is then converted into a a positive TTL 5V pulse using the 74HC14 Schmitt Inverter. The output from each layer is then measured for coincidence using 74HC08 2 Input AND Gate where the output of the below circuit will be sent to another circut to widen the pulses using a RC network and some more 74HC14 Schmitt Inverters.

Geiger-Müller Tube (GMT) SI-22G

I'll be using those good old Russian Geiger-Müller tubes again for this project. The are quite large 220mm with a diameter of 19mm. 

Working Voltage 360 - 440V
Initial Voltage 285 - 335V
Recommended Operating Voltage 400V
Plateau Length 100V
Plateau Slope 0.125% / 1V
Inherent counter background (cps) 1.16 Pulses/s
Cobalt-60 Pulse Gamma Sensitivity 540 pulse/mkR
Interelectrode Capacitance 10pF
Load Resistance 9 - 13 MOhms
Working Temperature Range -500 +700 С
Length 220mm
Diameter 19mm

Rough Layout without shielding