Direct access to particle-physics and astroparticle-physics experiments is often limited for students and the general public, as most research relies on large-scale and expensive facilities such as accelerators and telescopes. Recent advances in compact photodetectors and embedded electronics, however, have enabled the development of low-cost detectors suitable for outreach and educational use.
We have developed a compact and low-cost cosmic-ray muon detector named OSECHI (Outreach & Science Education Cosmic-ray Hunting Instrument). The detector is housed in a Japanese-style tiered box (Jubako) and consists of three layers of plastic scintillators read out by silicon photomultipliers (SiPMs). Stable triple-coincidence operation has been achieved with this configuration, and we have also evaluated a prototype 3D-printed scintillator by replacing one of the three layers. Signals from the SiPMs are processed by a custom readout board named COMOCHI COMBU, which integrates the functions of the analog front-end and digital control boards used in earlier prototype versions. The board handles bias control, discrimination, digitization, and data transfer through an onboard microcontroller. The system operates via a single USB-C connection, provides real-time LED indicators for muon events, and supports additional sensors such as GPS and temperature monitors.
Prototype versions of OSECHI have been tested in laboratory measurements and used in several hands-on outreach workshops with students and educators. Their feedback has been incorporated into the iterative design process.
We present the design and performance of OSECHI and report examples of its successful use in outreach and educational activities.