Gamma-ray detector for a sounding balloon

I teach Electronics and Internet of Things in a technical high school in Gubbio, Italy. Together with my students, we're developing a set of electronic devices to form the payload of a sounding balloon. We expect to launch it at the end of May 2024.

Among all, we want to send to the stratosphere a gamma-ray detector. Starting from the ground level, rising to over 30 km high, we expect to see an increasing level of gamma-ray radiation. This can be useful for my students to understand how invisible radiation can be detected and measured even with simple circuitry and to understand the role of the terrestrial atmosphere in filtering dangerous radiation coming from space.

The detector is based on three PIN photodiodes model BPW34. The signal is then amplified and made available to a connector where the input pin of a microcontroller can be wired.

The schematic of the system is shown here below.

The PCB has been designed taking into account the overall dimensions, its shape, and its weight. These three key factors combine to satisfy the requirements of our low-volume and low-weight sounding balloon.

The three PIN photodiodes work in parallel and are placed on the left of the PCB: in this way, they can be easily placed close to a gamma-ray source, for example.

On the opposite side, a four-way stripline connector guarantees communication to the microcontroller board.

The image below shows the PCB of the gamma-ray detector. 

For convenience, the sizes of the PCB are shown in the image: it is about 68 mm long by 13 mm wide.

To reduce the weight it is better to use a 0.8 mm thick substrate.

The image below, instead, shows the 3D rendering of the PCB with the components mounted on.

The three BPW34 are visible on the narrower part of the PCB.

The project is presented, described, and continuously updated at this address: https://doctoriot.wordpress.com/cota-cassata-on-the-air/