I’ve bought a couple of FEU84-5 PMT’s from an eBay seller because I’ve got an occasional low price.
I’ve extensivelly tested them with a 30 dia. 40 lengh (mm) CsI(Tl) crystal. Result? This tube is useless for spectroscopy. FWHM at 662keV vary from 11 to 13% uppon voltage setting! As comparison the same crystal coupled with a FEU85 gives me 7-7.5%. I’ve expected a better result from FEU84-5 because it’s multialkali photokatode is designed to couple with 550nm-light emitting crystals like CsI(Tl). Strange: I’ve obtained better results from FEU85 that’s made for 420nm light.
GENERAL SPECIFICATIONS Photocathode - antimony-potassium-sodium-cesium Optical input - front The diameter of the working area of the cathode - 25mm The number of amplification stages - 12 Wavelengths of maximum sensitivity - 420-550 nm green light Dark current - < 50 nA Sensitivity of the photocathode - 80 uA/lm Anode sensitivity - 80 A/lm Life time - more than 1000 hours Maximum Ratings : Max Voltage - 1900 V Max anode current - 5 micro A
FEU84-5 and it’s datasheet
It comes into a cardboard envelope with some sponge that starts to disintegrate after 30 years of storage. Nothing to complain… some paper and alcool and I’ve cleaned the tube.
FEU’s box
FEU’s sponge :3
This version of the tube doesn’t have a socket, it have just some teflon insulated wires. This is not bad…there is no need to buy a proper ceramic socket.
End wires
FEU front window
