All-In-One Gamma-Ray Spectrometer

More sensitive to gamma radiation than a Geiger counter with the added bonus of telling exactly what's inside your samples!

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Using a small custom PCB with a Raspberry Pi Pico microcontroller, a scintillator (typically NaI(Tl)) and a silicon photomultiplier (SiPM) you can build your own gamma spectrometer! The needed processing and multi-channel analyzer are all on-board so no external parts are needed, except something to look at the data (with a screen, obviously).

This detector uses a silicon photomultiplier (SiPM) instead of the usual photomultiplier tubes that are more common with these types of DIY projects. This means that the whole assembly is much smaller and also safer, because no high voltages are needed! Also in contrast to projects like theremino you don't strictly need a computer or even an external sound card -- everything is self-contained. You can do standalone measurements using only a USB power cable and save the spectra to the Pico's flash storage or connect to your PC via the Serial-over-USB connection.

Here are some of the most important key facts:

  • Compact design: Total size 120 x 50 mm. Approx. 70 x 50 mm area for electronics and additional 50 x 50 mm to mount a scintillator.
  • All-in-one: No external parts (e.g. sound card) required to record gamma spectra.
  • Easily programmable using drag-and-drop firmware files or the standard Arduino IDE.
  • Low-voltage device: No HV needed like with photomultiplier tubes.
  • Can use SiPMs in the voltage range of 27.5 V to 33.8 V.
  • 4096 ADC channels with built-in 3 V voltage reference.
  • Energy resolution of ~8% @ 662 keV possible; highly dependent on your SiPM/scintillator assembly.
  • Default (Energy) Mode: About 15 µs total dead time while measuring energy.
  • Geiger Mode: About 5 µs total dead time without energy measurements.
  • Low power consumption: ~25 mA @ 5 V with default firmware.
  • Additional broken-out power pins and I2C, SPI and UART headers for custom parts (e.g. display, µSD card, etc.).
  • Built-in True Random Number Generator.
  • Simple OLED support out of the box (SSD1306 and SH110x).
  • Built-in customizable ticker support.

More information can also be found in the GitHub repository...

Ok nice, but how do I get it?

  • DIY version: Download BOM and Gerber files or use Kitspace.
  • Buy a complete board: Head over to Tindie.

The principle of operation for the detector looks like this:

Read more »


BOM for the detector board

ms-excel - 2.03 kB - 04/11/2023 at 21:03



Schematic of the detector board

Adobe Portable Document Format - 115.81 kB - 04/11/2023 at 21:03


  • 1 × Raspberry Pi Pico Microcontroller and heart of this detector
  • 1 × MicroFC-60035 SiPM The silicon photomultiplier used with the scintillator
  • 1 × Main detector PCB Production-ready gerber file in GitHub repo or Kitspace
  • 56 × Components main detector board See BOM for exact parts
  • 1 × Scintillator For example NaI(Tl)

View all 6 components

  • New hardware revision?

    NuclearPhoenix09/20/2023 at 15:55 0 comments

    To break the silence, here is a short update on what's going on behind the scenes right now.

    At the moment we're looking into a possible hardware revision 4. This one mostly focusses on the PCB and component layout to improve shielding and optimize the total device size. There is a lot that can still be done in this regard and we'll test it thoroughly before release. In the best case this will keep on improving the energy resolution of the device and the new revision will also include some smaller quality of life improvements. Follow the project so you don't miss out on any updates.

    On another note, the OGD is sold out on Tindie, so thank you all for your interest in this project and the support. You can still get some of the Tiny MicroFC breakout boards if you want, the sale is still on until the end of september.


  • End Of Summer Sale

    NuclearPhoenix08/31/2023 at 09:51 0 comments

    From September 1st to 30th there will be a site-wide sale (-10%) on my Tindie Store, including the Mini SiD, the Tiny MicroFC SiPM breakout board and the Open Gamma Detector. No limit on the number of uses or products!


  • Tiny SiPM Boards on Tindie

    NuclearPhoenix08/22/2023 at 10:37 0 comments

    Finally, the Tiny MicroFC SiPM breakout/carrier boards are now available on Tindie! I have added some volume discounts for the PCBs and purchase options together with the Mini SiD and Open Gamma Detector.

    Link to the store page:

    Thanks to all the feedback and demand from you guys for the SiPM carrier boards. It's been long overdue to add these to Tindie so that you can get the PCBs together with the detector electronics.

  • Improved Case

    NuclearPhoenix08/19/2023 at 12:33 0 comments

    Here is a new and updated case design for the Open Gamma Detector Rev.2 and 3!

    It's a lost more compact and features friction fit slots for panel and display mounts. There are STL files for a default display mount for an SH1106 1.3 inch OLED screen and one for a solid panel cover. You can design some custom parts to fit your needs, especially with the front panel, and then just slot it right in.

    The detector main board is screwed in the bottom plate that is then attached to the top.  All the screws are designed to be screwed into inserts and the large front section of the case can fit up to a 5x5x5 cm scintillator.

    Just uploaded all the STL files to GitHub!

  • Temperature-compensated SiPM carrier board

    NuclearPhoenix07/26/2023 at 18:19 0 comments

    Hi there!

    Here is a new and updated revision of the MicroFC SiPM carrier board: It now has some extra circuitry for temperature gain compensation! The overall size of the PCB and the solder pads have not changed at all and the bias filtering is also still on there. In addition to that, you can also use it without any of the additional electronics on it too. Don't need temperature compensation or any of the filtering? Just leave out all the components on the back side and solder directly to the anode and cathode pads for the SiPM.

    If you do want to use the compensation circuit, a new BOM, Gerber file and schematic have been uploaded to GitHub. Kitspace should update too in the next couple of days (hopefully). Here is a link to the repo:

    It works completely passively without any sort of user intervention. It's based on an NTC thermistor that sits on the back side of the PCB, which is a big plus for temperature accuracy since it's on the same board as the SiPM. It's also low-power enough so that there is no unnecessary self-heating of the PCB. Just be sure to increase the SiPM PSU voltage a little bit as the compensation circuit initially drops a couple of 100mV to increase the temperature range without any need for readjustment. And ideally, you'd want to set the correct voltage at around normal ambient temperature for the correct tracking range (e.g. ~29.5V @ 25C).

    Most of the research and testing has been done by Sebastian D'Hyon, so big thanks to him.

    Finally, here are some screenshots on what the new board looks like:


  • FW 3.5.1: Tiny update

    NuclearPhoenix07/23/2023 at 17:15 0 comments

    Hi there! Just wanted to let you know about the latest update.

    This new version mostly just reduces code size and efficiency in the Arduino sketch. There are no changes on the usability part or the handling of the device in general. I dropped the akkoyun/Statistical library in favor for the more specific RobTillaart/RunningMedian lib. It's just a lot better suited for the job and will be even more handy in the future.


  • FW 3.5.0: Quality of life update

    NuclearPhoenix07/07/2023 at 17:44 0 comments

    Hi everyone,

    this newest firmware version is another quality of life update that improves general usability and a lot of the behind the scenes code. Most of the changes include the following:

    • Almost 10% reduction in energy consumption (this result has been tested with an SSD1306 OLED)
    • Slightly better timing accuracy with Gamma MCA: a few % less standard deviation for the cps value due to more accurate scheduling.
    • The geiger mode display will now show the unit "kcps" if the measured cps is higher than 1000. This helps a lot with the limited line space and should be enough for most use cases.
    • Possibly better higher cps behavior (not tested yet), because the first CPU core is now entirely free to process interrupts only. No other tasks run on this core anymore.


  • Project Showcase

    NuclearPhoenix06/21/2023 at 12:57 0 comments

    As far as I remember, I never really did a project showcase. However, there are already some pretty awesome projects out there, so I figured you'd be very interested! ;)

    This one's two beautiful portable devices built by user dc1rdb, one larger unit with a 1x2 inch NaI(Tl) scintillator and the other one a little bit smaller in size with a 1x1 inch crystal. The 3D printed handle and OLED mount are a great fit for this kind of thing and can be found on thingiverse. Also, look at these awesome buttons! He's also using the 2x2 6mm MicroFC SiPM array board with great results. He built both of these units with a battery and a buzzer with a little bit of custom soldering and the built-in software support for these parts. For charging the LiPo batteries, there's a standard USB charger PCB on the inside, that's wired up to the breakout pins on the Open Gamma Detector.

    That way, you can have a standalone device with recharging and not worry too much about any cabling. Let me know what you think about these! :)

    Read more »

  • New MicroFC Carrier Board

    NuclearPhoenix06/12/2023 at 20:03 0 comments

    Just released a new, extra small carrier board for the 6mm MicroFC SiPMs. It's only 10x10mm in size with the SiPM on the front side and all the solder pads + an optional RC low-pass filter on the back. Usability-wise it's exactly the same, but it's smaller! That makes it A LOT easier to use on small scintillator crystals.

    Read more »

  • FW 3.4.0: SH1106 support + ticker changes

    NuclearPhoenix05/21/2023 at 15:06 0 comments

    Hey there,

    you might have already seen the new firmware files on GitHub. With this new update, I added support for the SH1106-type OLED displays. This expands on the current support of SSD1306 screens.

    Also, in this update I changed the way the ticker works in order to accomodate higher count rates. The way it used to work is by clicking on each and every detected pulse. This way, you could only go up to around 1000 cps until the buzzer just saturates. Also, due to the already high activity at background radiation (>20 cps or so), detecting changes was a bit harder.

    That's why the ticker now only clicks at every 10th detected pulse. That way, you can get up to 10x the range for the buzzer without saturating. Also, stock background clicks are now way more relaxed.

View all 42 project logs

  • 1
    OPTIONAL: Solder SiPM carrier board components

    This is an optional step if you're using the carrier boards. If you're not and just soldering wires directly to the SiPM or doing it otherwise, skip this part. Note, however, that soldering wires to the SiPM itself is much harder than using the breakout board.

    You can choose to add the optional SMD components, to add some more power decoupling. This might help stability especially for longer cable lengths. If you're doing so, bridge the solder jumper and connect wires to VCC, GND and A(node) pads. If you're not using the SMD parts, solder directly to A(node) and C(athode) and the jumper remains open.

  • 2
    Couple SiPM with scintillator

    Center the SiPM on the scintillator crystal and put some silicon grease or other special coupling material between the two parts to optimize the optical coupling (and minimize reflections).

  • 3
    Wrap scintillator assembly

    Use black electrical insulation tape or similar non-transparent material to wrap the whole assemby, but watch out for the cables, of course. This will reduce light passing to the SiPM to an absolute minimum, otherwise it won't work properly. You should use multiple layers of tape just to be sure.

    Tip: I'm using tightly-wrapped Kapton tape on the outer-most layer to avoid the insulation tape from getting too loose.

View all 8 instructions

Enjoy this project?



ijcarlson07 wrote 08/09/2023 at 19:46 point

Hi! I am thinking about build your project, but I would like to be able to display the data on a Raspberry Pi touch screen, Would I need a whole new raspberry Pi 4 to do this? I would like to make this portable.

  Are you sure? yes | no

NuclearPhoenix wrote 08/10/2023 at 10:16 point

It really depends on the touch screen. You need one that works via I2C or SPI and has library support for the Pico/Arduino. Honestly, I'd just get some kind of breakout touch screen from Adafruit or something. They have great documentation and almost always some kind of library support for Arduino.

  Are you sure? yes | no

miles wrote 08/05/2023 at 21:58 point

Hi! I recently built your project, however when I got to the actual data collection I noticed there were a few problems in my spectra, the source of which I have been able to track. My setup uses a 1" by 1" cesium iodide crystal as well as the suggested MICROFC-60035-SMT-TR1 SiPM (and the active carrier board). One point where it deviates from the suggested design is 3' of BNC cables connecting the probe to the driver (all shielded and grounded). The actual problem that I have run into is when I go to collect background data the overwhelming majority of pulses are recorded at 209 (5,000 counts in 20min) as well as a second lesser spike at 217 of 1500, this is with 4" of lead and cement shielding. The average is 50.3 +- 200 cps. I have tried adjusting the gain with limited success. Do you know what could be the cause of this problem?


  Are you sure? yes | no

NuclearPhoenix wrote 08/05/2023 at 22:34 point

Hi! Does the spectrum otherwise look okay? It sounds like a noise issue to me. DId you try changing the discriminator threshold?

  Are you sure? yes | no

miles wrote 08/05/2023 at 23:08 point

I originally adjusted it quite a bit to get the estimated 10-50cps range (outside shielding). Other than the unusual spikes the spectrum looks about as expected. 

  Are you sure? yes | no

NuclearPhoenix wrote 08/06/2023 at 12:32 point

Huh, that's weird. If that doesn't help, maybe it's somehow an issue with the BNCs like Sebastian mentioned. An easy way to debug if it's a cable issue is to try and use some ordinary, short copper wires to connect directly to the SiPM board. If that helps, you know it's something to do with your BNC cables.

  Are you sure? yes | no

Sebastian D'Hyon wrote 08/06/2023 at 06:45 point

That is a large deviation for spikes.

Are you using Na or Ti doped crystal? The C series Onsemi sensors are better suited for Na doped crystals, but should still work for Ti, so this probably isn't the issue.

Also I found that a 1" crystal is better suited with a 2x2 array due to the large size.

I would perhaps check if you have any light leaks in your assembly. Also, if you're using BNC I would check to see if you're only grounding the shield at board side, it could be a ground loop issue?

  Are you sure? yes | no

gasel86895 wrote 04/22/2023 at 17:31 point

Hi, this is very interesting. I would like to understand your thinking in the preamp design and why a transimpediance preamp design wasn't used.

  Are you sure? yes | no

NuclearPhoenix wrote 04/22/2023 at 21:00 point

Hi, yeah I get this question a lot. In a nutshell, it boils down to saving cost and complexity. You could do that of course and it might (?) improve energy res by a couple %, but you'll pay that with multiple times the cost and complexity. That's just not worth it for this kind of device IMO.

  Are you sure? yes | no

NuclearPhoenix wrote 04/23/2023 at 10:53 point

Just added a new FAQ section on the design/cost thing if you want a more detailed explanation:

  Are you sure? yes | no

Sebastian D'Hyon wrote 04/20/2023 at 08:06 point

Hey, awesome project!

Any chance for a .step file for the PCBs? Would like to do some modelling for a custom case and shielding. I'll share whatever I make.

  Are you sure? yes | no

NuclearPhoenix wrote 04/20/2023 at 08:55 point

Hm, I don't think EasyEDA supports STEP exports. But I can give you .mtl and .obj files. Let me know if that works too!

  Are you sure? yes | no

Sebastian D'Hyon wrote 04/20/2023 at 10:11 point

This will work!

  Are you sure? yes | no

NuclearPhoenix wrote 04/20/2023 at 11:46 point

Just uploaded it to GitHub!

  Are you sure? yes | no

sukhjinder564 wrote 03/31/2023 at 16:27 point

Hi, I am trying to flash my pico with the firmware you have provided, but it does not reboot once I drag the .uf2 file over in Windows. I tested a simple LED blink program using MicroPython to confirm that I can communicate and run something on the Pico. Do you have any idea what may be occuring?

  Are you sure? yes | no

NuclearPhoenix wrote 04/02/2023 at 11:53 point

Hm, that's weird. So the micropython sketch works fine?

What UF2 file are you using specifically?

I'm not sure what could possible be causing this, especially since you had success with micropython. Did you flash the micropython firmware previously and then upload scripts via thonny or something like that?

  Are you sure? yes | no

sukhjinder564 wrote 04/03/2023 at 17:18 point

I was able to flash the board after compiling the sketch on your git, but the provided .uf2 file does not work. Not sure why. I had been using thonny previously. 

I have been noticing that the noise on the SiPM comes in at high energies (~600 keV!) - I cannot see the Cs137 peak well and cannot see the 511 peak in Na22. The assembly is light-tight, and I have adjusted the gain as well. Do I need to have a 50 ohm resistor on the anode? I currently have four wires soldered directly to the SiPM that are being fed into the PCB.

  Are you sure? yes | no

NuclearPhoenix wrote 04/04/2023 at 10:34 point

Okay, that is very weird. Especially since all the Arduino upload does is generate a UF2 file, reset the device and copy the UF2 to the device folder. So it's basically the same.

Anyways, did you calibrate the device with some known isotopes? Because the raw output you get is just the ADC channels, i.e. bins.

Are you using the SiPM breakout board? And what cables do you have connected? You only need 3 at max, one for anode, cathode and a ground.

You don't need any additional resistors.

Can you maybe send me a PM with one of your spectra please, where I can see the noise peak?

  Are you sure? yes | no

sukhjindersingh564 wrote 01/25/2023 at 19:37 point

Hi, this is a very interesting project.

I am having trouble finding any of the C-Series SiPMs in stock, do you think one of the J-Series SiPMs is a good alternative? For example the MICROFJ-60035-TSV-TR1?


  Are you sure? yes | no

NuclearPhoenix wrote 01/27/2023 at 11:28 point

Hi, just had a quick look at it and it seems like it would work. They look mostly similar to the C-Series SiPMs.

Another alternative for you would be the Broadcom Avago AFBR-S4N66C013.

I also have a breakout board for this:

  Are you sure? yes | no

Fabian Meier wrote 12/19/2022 at 09:01 point

Need some pointers in getting started with board from Makerfabs.

Hi NuclearPhoenix, great project - thank you very much for your time and effort.
I ordered a board from Makerfabs. I don't get any connection via USB - I don't see a serial port nor a USB flash drive (also by holding down the BOOT key). The LED ACT on the analog board is always on, I have about 20V on the PWR pin for the detector. It seems the RPI Pico board is not responding as it should. Did Makerfabs already download the Gamma Ray firmeware to the RPI? Thank you!

  Are you sure? yes | no

NuclearPhoenix wrote 12/19/2022 at 11:52 point


there is no firmware pre-flashed. It should pop up as an external drive as soon as you first plugged it in. Very weird that it doesn't react at all! If you press and hold the BOOTSEL key _while_ plugging it into the USB, your computer also doesn't recognize any external drive? Do you have any other Pico at hand to test it on that one, just to exclude any issues related with your computer?

If not, please hit me up with an email and maybe attach some photos of the board too.

  Are you sure? yes | no

Erhannis wrote 12/16/2022 at 22:04 point

Questions!  You mention it being sensitive to EMI - is that just the main board, or the SIPM, as well?  Could you put the main board in a box and wrap it in foil, and have the SIPM on an external cable?  Would having a long cable (maybe a meter?) between the main board and the SIPM introduce a lot of noise or other problems?  Thanks!

  Are you sure? yes | no

NuclearPhoenix wrote 12/17/2022 at 13:24 point

It's the main board and the SiPM as well. I wouldn't recommend long cables at all, except for shielded coaxial cables. Best case would be everything inside a grounded thin aluminium enclosure with as short cables as possible to the SiPM.

  Are you sure? yes | no

Chris wrote 09/15/2022 at 20:12 point

Hello NuclearPhoenix,
can I also connect a PMT with a NaI(Tl) scintillator? I will use a HV Splitter, so that only the pulse signal after the splitter can reach the signal input circuitry of your board.

So I mean can I replace your SiPM detector board with a PMT detector? If yes what will I have to care about?

  Are you sure? yes | no

NuclearPhoenix wrote 09/15/2022 at 20:51 point

Hi, if you manage to supply the detector board with positive (!) pulses from your PMT you could get this to work. I don't know the voltage (signal) levels you're dealing with in your setup of course, so definitely watch out to not kill the preamp by overvoltage. Absolute maximum rating is -0.5 to 3.8 V in this case, preferably 0 to 1.6 V.

Definitely let me know if you manage to get some results, sounds really interesting!

  Are you sure? yes | no

Chris wrote 09/15/2022 at 21:06 point

Hi, I had ordered the PMT and NaI(Tl) scintillator crystal from different sources. The HV power supply I am using can be regulated from DC to 1000V with a maximum of 2 mA. That should be enough to drive the PMT. It has a power divider at its end and needs only a HV supply of appr. 850 V for working. After that there will be a HV/signal splitter which separates the HV and the signals. I have to measure the signal level if I received both items and build together. I am happy to write the results here in your blog. Your board is already here (orderered from Makerfabs). They are really quick in shipping. After 7 days I received the board completey really professional build. Thumbs up!

  Are you sure? yes | no

Chris wrote 10/23/2022 at 16:30 point

Hi, now I got my NaI(Tl) Scintillator crystal and build als parts together for my PMT sensor. After calibration of my signal inverter amplifier (build in a shielded Al-housing with high qualitiy BNC connectors from huber & suhner) I played a while around with the trimmer settings till my scop says that the voltage peaks amplitudes are in the range of 400 mV to 1,9 Volts. Yess it runs!

Your Open Gamma Detector is showing cps rates... I have to reduce the PMT Voltage from 850  to 760 Volts, because NaI brings much more higher pulses as Bicron 412 Scintallators. That is impressive. The whole system seems to work now and I am playing with your Gamma MCA...

Fantastic project! Respect!

If you want I can post the hardware mods so that other interested readers can adapt it to their own PMT.

  Are you sure? yes | no

NuclearPhoenix wrote 10/23/2022 at 17:48 point

Awesome! Don't forget to turn down the preamp gain on the board if your input signals are already at 100s of mV, but best not all the way. You could also desolder one of the 10 Ohms feedback resistors next to the preamp to get a gain of 1 and fully turn down the potentiometer. This way you'll probably get the best range for your setup. Signals could then start at ~100 mV up to the 1.6 V max.

Please feel free to post more info on your hardware, I'm interested ;)

  Are you sure? yes | no

Jesse wrote 09/03/2022 at 13:27 point

Awesome little project, I work at a university in the nuclear engineering department but am not very strong in the EE area. I ordered one of the boards but I'm still looking for a SiPM chip. It appears all possible sources are back ordered. Would the evaluation board (MICROFC-SMTPA-60035-GEVB) be an appropriate substitute, it looks like these are still available? 

Thank you and keep up the great work!

  Are you sure? yes | no

NuclearPhoenix wrote 09/03/2022 at 15:59 point

Hi there, thanks for your comment and encouragement ;)

The MICROFC-SMTPA-60035-GEVB should work no problem, you'll only need pins 1 and 3 on it. The only issue might be the pin headers, though. I can't really tell from the images, but on the front side the solder joints could be actually higher than the SiPM itself so you wouldn't get any optical contact with the scintillator. Other than that you need to get it light-tight somehow and you're ready to go. Honestly, I would just desolder them and save some headache this way.

  Are you sure? yes | no

Jesse wrote 09/03/2022 at 16:37 point

Thanks for the reply. I hadn't considered some of those issues before. 

If I was to go with the AFBR-S4N66C013 as an alternative the spec sheets shows several more leads than the MICROFC-60035-SMT.

The spec sheets says "All cathode balls (C_1 to C_6) are connected together. All anodes (A_1 and A_2) are connected together. Unlabeled balls are floating, preferred electrical connection to cathode voltage. "

Would I only need to solder one wire to a single anode ball (ground), one wire to a cathode ball (power) and one wire to a single floating ball (signal)? Sorry for my ignorance on this. 

Also, would the MICROFC-10010-SMT-TR1 be another alternative?

Thank You!

  Are you sure? yes | no

NuclearPhoenix wrote 09/03/2022 at 17:32 point

Yes, the AFBR-S4N66C013 has a completely different package which is much harder to solder! According to the datasheet the anode must be connected to the SiPM voltage and the cathode to the signal pin. You don't need ground here. I haven't found any eval boards for this kind of SiPM, that would definitely come in handy!

I would advise against the MICROFC-10010-SMT-TR1 as the general photon detection efficiency is much smaller (and the size too of course). In addition to that its gain is also smaller by an order of magnitude. Maybe you could get the 35 µm version of the 1 mm SiPM, that might work again.

  Are you sure? yes | no

Jesse wrote 09/03/2022 at 21:05 point

Awesome, thanks for the help. I'll let you know how it goes. I'll probably stick with the MICROFC-60035-SMT and wait for stock to come in.

  Are you sure? yes | no wrote 08/29/2022 at 14:36 point

Will someone offering a complete "OEM" package including SiPM & Scint for those willing (like me) to pay but don't have the time to build?

George Hathaway (

  Are you sure? yes | no

NuclearPhoenix wrote 08/30/2022 at 09:11 point

Hi there George, I can only speak for myself, but currently I don't have the capacity to offer complete kits. I've started with the main detector board now and if there's enough interest, I'll also offer the SiPM on its little carrier board too.

  Are you sure? yes | no wrote 08/30/2022 at 16:26 point

Thanks for the reply. Hope someone might pick this (full OEM) up someday. Such a cool project.

  Are you sure? yes | no

ysyangsongzz wrote 07/19/2022 at 09:44 point

I will try the DIY project ,I hope you provide new information.

  Are you sure? yes | no

ysyangsongzz wrote 07/18/2022 at 09:47 point

Your answer:The energy resolution is at about 15% @ 300 keV, very highly dependent on the scintillator crystal of course and your whole SiPM/crystal assembly. In fact, I'm not even sure 15% is the best, it's just what I achieve with my simple used scintillator. I couldn't test it with Cs-137 at the nominal 600 keV yet.

My question:This resolution is a little poor. The resolution of normal Nai scintillator spectrometer can reach 7%~8%. Can the energy resolution be improved by changing Nai and increasing the number of SIPM?At present, this product cannot measure Cs137?

  Are you sure? yes | no

NuclearPhoenix wrote 07/18/2022 at 15:23 point

Like I said, I bought my scintillator used so I don't know the energy resolution 100% for sure. You will probably have a better resolution with a brand-new crystal from a reputable manufacturer. The detector can measure Cs-137, of course! I simply haven't come around to measuring it since I don't have it  at home currently ;)

In fact if you can get a great mount with the new SiPM carrier board, you will surely get an even better resolution. By the way, most of the cheaper commercial spectrometers have an energy resolution of up to 12 - 13% so that's not too far off. However, that's measured at the Cs-137 662 keV line so you can't compare it 1:1.

  Are you sure? yes | no

ysyangsongzz wrote 07/18/2022 at 09:20 point

OK,NuclearPhoenix .I see it again.

  Are you sure? yes | no

ysyangsongzz wrote 07/18/2022 at 08:29 point

Hello,NuclearPhoenix .Is the NaI crystal used  one inch in the DIY project? SIPM is 6mm*6mm. I want to ask how SIPM and Nai are coupled to ensure the photon collection rate.  THe energy resolution question in the PMs,the PMs is what?

  Are you sure? yes | no

NuclearPhoenix wrote 07/18/2022 at 09:15 point

The coupling process is described in the build instructions and on GitHub. "PMs" are the private messages here on Hackaday, you sent me a message there.

  Are you sure? yes | no

ysyangsongzz wrote 07/15/2022 at 00:36 point

Hello,NuclearPhoenix .How many sipms are used in this DIY projet? What is its resolution to Cs-137? Schematic v2.0 version has been released on GitHub website. When can the corresponding v2.0 PCB be released?

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NuclearPhoenix wrote 07/15/2022 at 12:05 point

Just one SiPM, otherwise I would have stated so in the documentation. The PCB is already released on GitHub. I already replied to your energy resolution question in the PMs.

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ysyangsongzz wrote 07/14/2022 at 02:42 point

Have you considered the temperature drift of SIPM?

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NuclearPhoenix wrote 07/14/2022 at 15:51 point

No, it's not temperature corrected since this is a DIY project designed for use in controlled environments. Of course there is some drift, but if you use it close to the nominal 25°C you will not notice it.

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Wesley Ellis wrote 05/19/2022 at 00:36 point

Neat project, but I think there's a typo in "a USB power cable and safe the spectra to the Pico's flash storage" where safe should be save

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NuclearPhoenix wrote 05/19/2022 at 09:17 point

Yes, thank you!

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yahyabangash2004 wrote 05/06/2022 at 16:06 point

Good initial

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