Bicron Surveyor M mod - PIC scaler BIG POST

[Seoul_lasers]

Well, there will be some more updates on this project coming very shortly.

I finally got my replacement Yocto-PMW-Rx signal board after my Rev A developed a strange issue with its flash memory. I sent it back on November 20th and received the replacement on December 27th, over a month later.

I learnt the hard way never to use Royal Post mail and hand it off to Canada Post, you may never see the parcel again. Canada Post has a dispute going on with royal Mail over its refusal to
pay royalties to Canada post over its tracking service within Canada. So, any Royal Mail package with get the bottom treatment by Canada post purposefully.

Anyways, I have the Rev.B sensor board now which I will install into the unit after thoroughly testing it.

I will then make a "signal out" socket on the surveymeter case as well as a USB connector for the sensor board.

:can:

more coming

 

[Seoul_lasers]

A major new update on this ongoing project.

I installed the YoctoPMW-Rx module into the Bicron Surveyor MS and wired it for 2 channels. So this little board does CPM/CPS/Pulse duration and duty cycle all at the same time and sends it over a network connection to be remotely graphed or graphed in real time without the need for a driver on an Android powered tablet or PC (via Yoctograph,influxDB, Grafana or even TI LabVIEW) Pretty useful if I might add. All of these measurements are good until
250Khz which is the boards maximum sampling rate.

you can clearly see 2 wires coming off the board here (one red and one orange) Both wires carry a CMOS level signal from the MC14538BCP chip. Pin 9 carries an inverted signal, whereas
pin 10 carries a positive signal and can be used to interface directly to RH Electronics Gamma rate meter.

The YoctoPMW-Rx board was epoxied on to miniature 2.5mm standoffs and then epoxied onto the back of the analog meter. I set the illumination of the LEDs at the back to 1% illumination.

On the back of the analog meter is a 2mm thick coating of electronic grade silicone potting compound/glue which I attached the bicron board on. If I ever need to remove the panel I can do so easily. The silicone will peel off one I release the edge of it with an exacto blade. Silicone potting compound/glue was also used to hold the wires onto the board and protect their connections from accidental breaks. ( acts as a connection stress relief) The orange wire has an additional safety feature. A quick disconnect. The black connection fits a signal wire that terminates to a SMA connector mounted onto the front of the Bicrons case. This allows the Gamma rate meter to pick up the signal.

This is the picture of the board connected to an LG G3 phone running Yoctograph by Yoctopuce.

I am using this with my plastic scintillation detector set to 1150V. Background here is around 300-350CPM.

USB (mini-B) socket terminating out the front of the survey meter. The USB cable is stripped and then re-bundled to get it through the board's central hole.

 

[Seoul_lasers]

Can't help with your challenge, but it looks like a very nice meter. You don't see a lot of analog meter movements any more.

I have a little update on my Bicron Surveyor.. I have a new (mint condition) Harshaw 2"x2" inline NaI/Tl scintillation detector incoming that is spectroscopy grade. It will have a 14pin socket with a 120Mohm dynode string for low current operation.
I'll post a picture of it when it gets here. I'll also be using it on my Theremino PMT driver with a known isotope to test the Energy resolution.

Should be great.

 

[paul1598419]

Sounds great. I was in the hospital at the end of last year and was recuperating for several weeks after spending more than a month there. I missed out on some of your posts, but I'm back now. + Rep. :yh:

 

[Seoul_lasers]

I received my early birthday gift from a fellow member of the Gamma Spectroscopy yahoo forums, a 2"x2" Harshaw (inline) NaI/Tl detector along with a single wire 14pin socket base from iRad labs out of Florida.

The detector is a very heavy, well built (hermetically sealed) with MU liner, with a perfect crystal & sample well. It was used at a University for high precision sample spectroscopy. I think the ballpark figure for a new one is around $3500CDN just for the head. I got mine for under $60CDN used.

Anyways, I tried the unit on my Bicron set at ~1000V, which gave me around 400 - 450CPM background. Moving over to my kitchen countertop, (Brazillian marble) gave me a reading of ~2500-3000CPM. Thorium content I think. (Monazite).

I then gave the unit a test using the Theremino PMT Adapter using Am241 and then some NORM (Uraninite)

The resolution is quite good, but I feel that the Theremino software needs some fine tuning.


My test with Am241 shows the 2 peaks at 26KeV and 59Kev.. very detailed even at 800V. Best at 1Kv.

The spectrum attached is of a Uraninite sample. The software gain needs adjusting but you can get an idea of the spectrum from all the decay products of U238 & U235: Pb210, Bi210, Pb210, Bi214, Ac228...etc


More testing needed, but so far so good!

 

[paul1598419]

Nice snag. :yh:

 

[Seoul_lasers]

Just showing off a spectrum of am241 from my 10uCi. I also tried a 60uCi and a 160uCi source (which proved to be too much and saturated the ADC)

Here we see in the first shot ... a very angular bin, done at 0.1x

in the second shot, we see two peaks 59.54KeV and (69.77KeV Np237) and a small bump to the left, which is the low energy Gamma at 26.34KeV from Am241

 

[paul1598419]

Very cool. It seems you've worked all the bugs out. I am out of reps, so I'll owe you until I get another chance to rep you again. :yh:

 

[Seoul_lasers]

Very cool. It seems you've worked all the bugs out. I am out of reps, so I'll owe you until I get another chance to rep you again. :yh:

Not exactly. I have come to the realization that this probe is more suitable for gross counting low activity samples than conduct spectroscopy. However,
I am still able to see the photopeaks of Am241 and the ones from Ra226 alright. but anything less than 30KeV has some trouble getting through the wall of the detector and doesn't really show up.

However, I guess I got lucky with the 26KeV line just sneaking through with my lower activity source. ---> I think therein lies the key. Lower activity... better results. :can


Ra226 - at 905V Gain 3.7x -- not calibrated here... There is a tiny peak towards the middle of the slope at 186KeV which is our target material.

Am241 (10uCi foil source in well for 30 minutes with a gain of 2.0x) Note that the 59.54Kev overtakes the entire Spectrum - with the Np237 peak beside it.

 

[paul1598419]

So, are you back to searching for the right detector? How many PMTs do you have now?

 

[Seoul_lasers]

So, are you back to searching for the right detector? How many PMTs do you have now?

I have 2 unused PMTs that don't have scintillation crystals yet, 2 NaI/Tl detectors, 1 CsI/Na 18mmx23mm which I home rolled, 1x plastic scintillation detector that is both Beta an Neutron sensitive.
I am getting another scintillation detector soon. It will be a solid crystal.
I am selling the through hole one for ~450USD. Normally a detector like this is about $700 used. This one turns out that it was used to detect fission products in nuclear fuel, hence the hole to run the fuel rods through them. So while they aren't designed for spectroscopy per se, they can definitely detect isotope signatures with some cut off at the lower energies.

 

[paul1598419]

I'm happy to see you are able to keep this project alive by selling off what you don't need. I look forward to your next update. :yh:

 

[Seoul_lasers]

So, I just got my Cs137 source by mail today. It's really weak, something in the neighbourhood of 0.2-0.3uCi.. The surface activity is only around 1300CPM.
(that's around 3.9uSv/hr if you're using a LND7317 pancake probe).

So, I had a bit of a discovery about how to get the best resolution from the 2"x2" Harshaw detector. It turns out that running the detector at 1250V, the a sample Isotope on the thin side of the detector housing (upper portion), with a software gain of 2 in Theremino MCA, yields the best results.

Spectrum after 1minute of sampling (note the distinct compton backscatter peak and plateau.) ... the 662 peak is just popping up to the right.

0.9uCi Am241 source up against the tin wall of the detector.

Am241 in PRA, done at the same time as the above spectrum in theremino.
(Theremino MCA 7.1 has some major issues in linearity )

CsI/Na 18x30mm probe detecting Cs137... This crystal is denser than NaI/Tl
therefore it can resolve the Cs137 peaks quite well for its size. However, you can see that the compton scatter / peak is not quite as well defined. A little muddy.... Still impressive though. The two peaks are still very distinguishable.

 

[paul1598419]

I forget what software you are using to resolve the spectrum. Is it an OEM or something you put together? It is fascinating to see you continuing to make this spectrometer work.

Oh, and + Rep.

 

[Seoul_lasers]

I forget what software you are using to resolve the spectrum. Is it an OEM or something you put together? It is fascinating to see you continuing to make this spectrometer work.

Oh, and + Rep.

No, not OEM, actually there are several programs that are free to use all based on sound card usage. Also open source...

1# Theremino MCA (I use this one as it is the most commonly used)
2# PRA / Pulse Recorder and Analysis (Has very good Gaussian filters) I also use this one.
3# Intune (for making calibration files)
4# Beqmoni 0.9 A little strange to setup - sometimes fails to work at all.


5# portable ( iPhone Geigerbot) (Android Atomspectra 3)

2 different projects going on here... the Bicron project which is nearly complete (a few mods left to do) and a Gamma spectrography project.

 

[paul1598419]

:thanks: