First, I hope this is the correct place for this question. I am experimenting with electrical discharges at low pressure, think plasma globe, and I bought a geiger counter to make sure I am not producing x-rays. My vacuum pump is rated down to 5 pascals. The problem is that the geiger counter is set off by the RF noise from the tesle coil. Using grounded metal shielding reduces this noise is greatly, but how can I tell if the geiger counter is in fact picking up x-rays? Currently the counter only picks up a reading when very close to the discharge. X-rays should still be strong at more than 10-20cm from the source, right? The geiger counter also only goes off when using the tesle coil, and reads nothing when I use a high voltage DC supply. What do you think?