Category: Photomultiplier tubes

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

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.

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.

 

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

Specifications
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.