On cold days, I must carry the gamma box in an inner pocket with the window facing my body and adjust the shaft occasionally to maintain an occasional pop. A location close to the body core thermostats much better than one farther away (e.g., a shirt pocket is preferred to a pants pocket). When returning inside, I advise any users to let the unit warm up and readjust the shaft before approaching any putative radiation hazard. When indoors, determine when the maximum daily temperature occurs in your workspace and adjust the shaft at that time for about one pop every 2 s on average. Almost all of these pops are just shot noise and serve to indicate that the detector is set to maximum sensitivity. 

Actual radiation exposure sounds like a zap or buzz (but check whether a smartphone is nearby; at very close range they can cause false positives). Actual radiation exposure also produces a range of physical symptoms, the most diagnostic of which are tinnitus and shitting your pants. 

For best privacy and least interference, minimize the length of the earbud cord by coiling up the slack and attaching the coil to the box with a 4" length of monofilament breadboard wire.

  • Dim.: 6.125” x 3” x 1.375” (pocket-sized)
  • Weight with Li-ion battery: 300 g.
  • Output jack has been waterproofed.
  • Battery is external for easy changing and testing.
  • Power and signal jacks are Zener-protected at 12 V.
  • One shaft provides both power on/off and threshold fine-tuning.
  • Convenient access to threshold coarse-tune.
  • An epoxy window allows access by weak radiation (e.g., 241Am) to the photodiode for verification purposes. 
  • Two hanger rings on the box allow suspension from a lanyard or carabiner.
  • Long battery life (2 weeks, always on).

This post is mostly to test how much interest this project generates because I am considering commercialization on Tindie.

Figure 2 is a bonus quick orientation to radiation shielding choices. Denser is better, but obviously cheaper is also better. CON, concrete. Water is not so dense but is off the bottom of the price scale and is very much a contender if you have the space.