I discovered a while back that you can homebrew a relatively good alpha detector using:-
1 piece of pyrolytic graphite (Greedbay, £15)
1 cheap monochrome CMOS camera
A replacement crystal, I used a 4.43 MHz one robbed from a defunct TV
A tube of slow epoxy
A paif of gloves
1200 grit sandpaper
Silica gel granules
Black CD marker
All you do is thin down the PG (you can use the other bits for levitators, etc)
Once a good thin piece is obtained, sand it down to as thin as you can make it with 1200 grit.
Clean up with your favourite solvent to get rid of any carbon dust.
Dismantle your cheap CMOS camera (I used an old B&Q one) and then CAREFULLY remove the lid to expose the bare sensor with attached fine wires.
Epoxy around the edge so the wires are covered but not the sensor.
I found that positioning the sensor at a 20 degree angle for each section helped here.
I also advise putting a single small blob of silica gel on the edge with no contacts with an air path to the sensor as otherwise water vapour will ruin it in short order.
Allow to dry, then retest camera. If all well prepare another tiny drop of Epoxy.
If you wish you can also add a strip of Xray scintillator film onto the bottom edge of the chip with the light emitting side facing downwards.
Epoxy your PG sheet down and then dry the whole assembly out at 50 degrees for two hours.
Test camera, as you will need to determine where any light leaks are.
Then paint the Epoxy with Tippex, dry out and retest.
Overcoat with CD marker and then paint the back and edges of the board as well leaving a gap around the crystal.
I also tend to disable the automatic iris pin if present with a 1K resistor to Gnd.
If all is well, replace the 13.5 MHz crystal (or 16 MHz) with your 4.43 MHz one.
Test camera, you should not have stable video BUT it will work fine on a 'scope.
The alpha sensitivity should be approximately 2.8* efficiency with 13.5MHz (!)
Particles show up as vertical spikes on your scope display.
This is also theorised to work on linear CCDs from old printers!