Info on some PMTs?

Scintillation crystals, PMTs, voltage dividers etc...
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brehwens
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Info on some PMTs?

Post by brehwens » 08 May 2015, 22:37

Hi guys!

I recalled having a few "odd" PMTs in the toybox that I got a good while back. One I tested, and it was broken, but a few of the others I have not tested yet, parly because I have no data sheets on how to wire them.

The first one is a Hamamatsu R374 HA. While the tube per se does not seem to be anything special, the end window is not clear, but "frosted". Does anyone have any idea what the reason for this is, and maybe have a data sheet?
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Hamamatsu R374HA
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Hamamatsu R374HA
20150508_141808.jpg (2 MiB) Viewed 4988 times
The other two tubes are quite old 2-inchers, but I would still like to test them so I can throw them away if they are broken.

One is a Philips 153AVP
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Philips 153AVP
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The other one has no brand name on it, but surely a symbol you seasoned PMT-nerds can identify
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R375
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So, you guys have any intel on these?

/Karl
Karl Brehwens
Eskilstuna, Sweden.

Setup: 5 cm lead castle, 2mm copper lining. Gamma Spectacular Pro 2002, Sound Blaster Live! 5.1,
Primary detector: Scionix refurbished 2x2" NaI(Tl) well detector, 7.5% @ 662 keV

valentin
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Re: Info on some PMTs?

Post by valentin » 09 May 2015, 00:24

Hello Karl,

The frosting on your R374 might be HA coating, according to https://wwwmu.mpp.mpg.de/docs/pmtconstruct.pdf :
when using foam rubber or similar material to
mount the tube in its housing, it is essential that material having
sufficiently good insulation properties be used. This problem can
be solved by applying a black conductive layer around the bulb
and connecting to the cathode potential (called HA Coating)
Does the last tube look like this : http://www.hamamatsu.com/us/en/R375.html ? If so, just google for "hamamatsu R375 datasheet".

Valentin

P.S. Sorry for not posting an "introduction" in this new forum, first. I promise to do so ASAP.

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brehwens
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Re: Info on some PMTs?

Post by brehwens » 09 May 2015, 21:49

Hi Valentin!

I had a look at the link (thanks!) but I couldn't get my head around if the HA-coating was only the black "film" around the PMT, or if the frosted window was also a part of this (some kind of frosted conductive layer, but slightly transparent). I am also curious as to what tradeoffs in terms of performance this modification can involve.

I will double-check that Hamamatsu PMT, but it sure looks very similar from the pictures. Thanks!
All that remains now is to see if these puppies actually work..
Karl Brehwens
Eskilstuna, Sweden.

Setup: 5 cm lead castle, 2mm copper lining. Gamma Spectacular Pro 2002, Sound Blaster Live! 5.1,
Primary detector: Scionix refurbished 2x2" NaI(Tl) well detector, 7.5% @ 662 keV

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iRad
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Re: Info on some PMTs?

Post by iRad » 10 May 2015, 08:17

Hi Karl - The HA coating is for shielding, and not used over the cathode. The tube could have been used for liquid scintillation or some other purpose. This is done for dealing with issues relating to spatial uniformity or polarization. When head-on tubes are used instead of side window, they will usually use a diffuser in front of the window or have their window frosted. They could have also had a completely different use than for scintillation counting also. The tube may not be all that useful, but would always be fun to experiment with.

May times you can figure the leads coming out of a PMT by tracing where they go inside. If you familiarize yourself with the inner workings, you can easily learn to identify the cathode, grid, dynodes, and anode. Then just a simple matter of following the "rungs on a ladder" to figure the wiring pattern. The only problem with that is figuring out the voltage divider ratio, but starting with common ratios for similar PMTs has worked for me often.

It may or may not be worth the effort, as far as cost of time verses gain of a questionable quality PMT. But if you figure it's a good opportunity to learn, then there is where the value of the exercise is.
Last edited by iRad on 11 May 2015, 08:27, edited 1 time in total.
Please check out my eBay Store: http://stores.ebay.com/The-Rad-Lab
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Steve Dubyk
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Re: Info on some PMTs?

Post by Steve Dubyk » 11 May 2015, 07:30

Here is the spec sheet for the R374, which is quite different than the R375. I use a high gain version, the R1104, and that information is included also. I also have a few PMTs with the frosted window, and they work well for gamma spec purposes.

Steve Dubyk
Attachments
Hamm_374_R1104.pdf
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brehwens
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Re: Info on some PMTs?

Post by brehwens » 11 May 2015, 18:10

Hi Steve and Tom,

Thanks for the information! It looks lite the wiring is the same as for another 1" tube (actually two) I have, that also looks almost the same. The classic "jump across" wiring. Should be able to just pull that socket and give it a test...

Tom; thanks for the tip on how to figure out the various pins... I realized this, but at the same time, I do all my "fiddling around" after 8 pm when the kids are sedated...I mean sleeping, and am quite tired myself so it is nice to have a proper reference to exclude "exhausted parent" -factor :)

I also see you have stepped up your Ebay listings; now more nice stuff to choose from than ever. I get a bit sentimental seeing the Thorn EMI 9956KB tube, I used that one for my very first probe build that turned out excellently!
Karl Brehwens
Eskilstuna, Sweden.

Setup: 5 cm lead castle, 2mm copper lining. Gamma Spectacular Pro 2002, Sound Blaster Live! 5.1,
Primary detector: Scionix refurbished 2x2" NaI(Tl) well detector, 7.5% @ 662 keV

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iRad
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Re: Info on some PMTs?

Post by iRad » 11 May 2015, 21:34

Karl
Often similarly pined tubes are physically wired the same, and I have never personally damaged one by just trying an already standard wired socket from another PMT. Sometimes optimum linearity, stability, or count rates might require a specific VD ratio, but usually they will at least work with standard VD ratios (provided the pin-outs are similar). So probably nothing to loose by trying.

I'm working on expanding my listings once again, glad you noticed. I get very frustrated with eBay sometimes, but the venue does make it easier to reach a wider audience. I'm in the process of opening up an eBay store "The Rad Lab", and hope to ad an even wider array of items in the coming months. Like you, I'm always short on time and don't know where the days go, and my kids are long gone. Don't know how you young folks with kids and busy lives find the time to enjoy your own interests. I know for you, this is a hobby closely related to your academic and carrier life, so the group is very fortunate that you are able to spend some of your precious time and knowledge here, thanks! Cheers, Tom
Please check out my eBay Store: http://stores.ebay.com/The-Rad-Lab
Cheers, Tom Hall

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brehwens
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Re: Info on some PMTs?

Post by brehwens » 11 May 2015, 22:03

Tom,

Yes, I also suspect a standard VD design will allow me to test if the PMT is working or not, I am more worried to make some bad connection and fry the thing (or something else).

Well, I can't say that I am making the progress I would like to with my hobby but at the same time it is kind of nice to have a few projects floating around, waiting for attention.

As for my academic career; I am currently making a transition out of academia (I can't see my future in it) and my hobby has for sure made that decision easier as it provides an outlet for the scientific thinking and methodology I have picked up and enjoy, Also, I feel there is so much for me to learn about the "hardware" side of radiation. In the process, I might be able to share a thought or two about the biological aspects of radiation, which was my focus for my thesis work. More on that in a separate thread... when I get the time! :)

Good luck with your ebay store, looking forward to adding it to "my stores" in the near future!
Karl Brehwens
Eskilstuna, Sweden.

Setup: 5 cm lead castle, 2mm copper lining. Gamma Spectacular Pro 2002, Sound Blaster Live! 5.1,
Primary detector: Scionix refurbished 2x2" NaI(Tl) well detector, 7.5% @ 662 keV

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iRad
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Re: Info on some PMTs?

Post by iRad » 11 May 2015, 22:58

I don't think you will hurt anything by just trying. Besides, if we are talking about the R374, the data sheet Steve shows a standard pin layout. You should be able to use the same VD recommended in the Theremino documentation for the R6095. That works with many other similar tubes as well.

Playing in a jazz band could be a satisfying career. If you don't mind the late hours and low pay that is. :)
Please check out my eBay Store: http://stores.ebay.com/The-Rad-Lab
Cheers, Tom Hall

Neil.
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Re: Info on some PMTs?

Post by Neil. » 17 May 2015, 04:09

Hi, Karl,

The R374 was the first PMT I used for scintillation work. It was given to me years ago by a fellow ham operator. It was a service pull so it was used but it worked. Mine does not have the shield or frosted head end though.

I use this with a 3/4 x 3/4 inch crystal for portable counting. When tested with Cs137 this probe gives a resolution of 8.3%. I tested this tube at many voltages and found 1000V works the best.

Here's a documentation sheet of my probe from my files. The PMT pin numbers are shown so I hope this helps.

Neil
374 PMT.jpg
374 PMT.jpg (140.3 KiB) Viewed 4924 times
Neil Edwards
Dublin, Ohio, USA

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