FEU84-5 ФЭУ-84-5 PMT photomultiplier tube for gamma spectrometry

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.

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

Click to download


Hamamatsu R6095 photomultiplier tube

I’ve bought this R6095 PMT tube from iRad ebay seller. It cost me about 40$ plus shipping. iRad sells it as just tube or with socket and voltage divider kit. I’ve bought the complete kit.  A link to his auction: iRad

R6095 PMT from iRad
Minimum Wavelength 300 nm
Outside Diameter 28 mm
Peak Wavelength 420 nm
Maximum Wavelength 650 nm
Viewing Direction Head on
Rise Time 4 ns
Photocathode Material Bialkali
Window Material Borosilicate
Anode Current 0.1 mA
Typical Photocathode Luminous Sensitivity [µA/lm] 95
Photocathode Peak Radiant Sensitivity [A/W] 0.088
Gain 2.1 x 10e6
Max. Supply Voltage Between Anode and Cathode 1500 VDC
Max. Supply Voltage Between Anode and Last Dynode 250 VDC
Operating Temperature -80 to +50 °C

This tube could be used to make a nice scintillation probe coupling it with a 30mm diameter NaI(TI) crystal and feeding 800-900V. Yes… just 900 and you can expect a gain of 10^6. Within the box there is the datasheet of the tube plus an instruction sheet to wire the voltage divider network to the socket.

Tube plus socket and instructions