The Theremino_MCA while being completely Freeware and OpenSource is a true multi-channel-laboratory Analyzer.
– Electrical schematics and Assembly plans: www.theremino.com/technical/schematics
– Software: www.theremino.com/downloads/radioactivity
– Hardware, DIY and kits: www.theremino.com/contacts/producers
– Images and videos: www.theremino.com/video-and-images
– Article about Open Source Electronics: crafts-to-gamma-spectrometry-signal conditioning-of-
Hardware for the Gamma spectrometry
The Theremino_PmtAdapter contains a feedback loop that can keeps the tension stable even in the presence of strong temperature fluctuations. In this way the calibration remains accurate over time and rows of isotopes do not move and do not expand.
ATTENTION: For optimal performance use pipes PMT wired as shown in the file PmtAdapters.pdf – PMT for low impedance tubes (with resistors 1 Mega or even from 560k) cannot operate with these adapters. To use them you should replace their resistors, as indicated.
This adapter can be used with the well known freeware software PRA (We thank Marek Dolleiser for having paved the way for this kind of analysis, its software PRA is a reference for many years and helped a lot) but only with the Theremino_MCA you can do filtering and deleting useful background to get maximum information within a reasonable time.
This file includes the design of PCB, le immagini e le simulazioni SPICE: PMT_Adapter_V3.1
This is version 3.2 con molti piccoli miglioramenti: PMT_Adapter_V3.2
This is version 3.3 con ulteriori miglioramenti: PMT_Adapter_V 3.3
Most salient features:
– Compact only 50 X 70 mm
– No initial thermal drift due to the feedback loop.
– Adjustable voltage from 500 to 1500 V
– Very low power consumption only 10 mA @ 5 V
– Very low ripple only 100 UV
– Protected against short circuit
– Maximum power output 100 MW
– Preamp circuit and pulse enlargement (from 3/5 uS to 100 uS to be read by a PC sound card)
– Compact only 50 X 70 mm
– No initial thermal drift thanks to the feedback circuit.
– Adjustable voltage from 500 to 1500 V
– Very low consumption at 5 v only 10 mA
– Ultra-low ripple only 100 UV
– Protected against short circuit
– Max power output 100 MW
– Preamp circuit and widening of built-in impulses (carries impulses from 3-5 us to 100 us to be read by a PC sound card)
The simple and neat reduces manufacturing defects and makes them readily apparent.
In the following pictures you see the PMT in rehearsal.
The circuit diagram and an impulse to sample that shows the noise level of ’ power supply, Note that this is a low-energy pulse.
In the latest versions of PmtAdapter noise is less than 100uV. Practically the only noise due to sampling in 16 bit soundcard, as shown in the two following images.
The first picture shows only noise sound card, the second noise with a separate connected.
The complete system
The Pmt Adapter is not in production, You can build it but contains a number of special components, hard to find and expensive. So we recommend that you contact Lello, who knows how to find a cheap components and also print a number of PCB for friends: email@example.com
The theremino team only deals with research and does not sell hardware. The system is completely "Freeware", "Open Source", "Not for Profit" and "DIY", but there are manufacturers who can provide modules assembled and tested at a great price. One could hardly self-build them spending less. For a list of the producers read this page: www.theremino.com/contacts/producers
A hoof to the Hamamatsu PMT R6095 (and the like)
In this ZIP file the complete project Eagle and the GCode for the cutter: PMT_Socket
These pictures show how to adapt the connectors to printed and how is the plinth ended (click on images to enlarge them)
The capacitor might also be welded across (with two insulating sleeves on leads) and, to avoid short circuits with the outer aluminum tube, It is good to wrap the whole area from PMT to printed circuit board, with a sheet of plastic sheet..
An MCA system for Apple (iPhone and iPad)
By popular demand Alessio has designed a special version of PmtAdapter, usable with software available on iPhone and iPad. The software is called Geiger bot, ed è un riferimento per la comunità Apple.
The circuit diagram is very similar to PmtAdapter for PC, but I added a battery (There is the ’ USB powered). The signal amplitude is reduced considerably, You can send all ’ mic input, that otherwise would saturate and would distort the pulse shape.
Here you can see the spectra obtained with Americium and cesium. Thanks to the wonderful display resolution “retina”, the words are so small, that do not disturb the vision of the beautiful black background.
We are light years away from a true MCA, line width “FWHM” (that is the most important parameter for an MCA) is overwhelming. Minor details of the spectrum are completely invisible. Here's the same Spectra produced by Theremino MCA:
With a Tablet 12 inches by 180 Euro (with Windows 10 and shipping included in price), you would have a portable instrument much more convenient and accurate. But the satisfaction of using an Apple system, It costs an exaggeration, is priceless!
Calibration and temperature
The Pmt Adapter and the photomultiplier consume only a few tens of milli Watts, that are insufficient to cause significant temperature variations. So you don't have to wait for a “warm up time” between the ignition and the measures. And there ’ is not even a progressive warming during very long measurements.
Though the crystals change with ambient temperature performance scintillators, as you can see in the image below:
Note that the response to temperature is not linear and that changes even slope from positive to negative, right in the area of normal temperature. Whereby an automatic correction would be inaccurate. It would take a correction table to be calibrated for each Crystal and this would be very complicated and ultimately unreliable. Much better make an adjustment with two markers before each measurement.
Check with the marker before each measurement is quick, accurate and very reliable. It is recommended to keep in place two small samples (for example, Caesium and Americium) at appropriate distances, so you always have two small rows of reference. Caesium is weaker and you hold it close enough to the probe while l ’ Americium hold about ten centimeters, or is enclosed in a capsule, to decrease its activity and keep him close to the probe.
The two lines should be the same height and small enough not to disturb the measurements. If you do not have to measure precisely the cesium and l ’ Americium, then the two markers can always stay in position. See their lines on the final chart (possibly commented) from the security that the chart is perfectly calibrated.
Build a well in lead
To use to measure the level of radioactivity and radioactive substances, natural background.
The measure consists of a base plate, plus some concentric cylinders, of various sizes and thicknesses. Among the components leaves something’ of slack, in order to facilitate the Assembly ’.
The material is actually brass lead, to distinguish it from the ’ probe grey aluminium, While the piece of inner cylinder (barely visible) is the unique ’ of plastic, with concentric ring in lead.
All the lead parts were made from sheet metal 1,5 mm thick, cut with a common Bill-sheet and shaped by hand, wrap around cylinders of aluminium/steel/plastic I had available (used only as “DIME”).
The base plate is made by folding several times a strip of sheet metal of equal width, getting a decent thickness.
Sheet bends easily around the straight edge of a table and flattens with hammer taps. The lead is very malleable.
All the pieces were wrapped with paper wide enough, so handle them does not come into direct contact with lead, that tends to get your hands dirty. Also why is good to calculate a little’ of slack between the various diameters of pieces, so then that paper coating doesn't break any insertion/extraction of cylinders all ’ same, that partially must fit one inside ’ more (as for the cylinder and top shirt)
To measure you follow this pattern:
- First arises on a table the base plate and the cylinder base;
- You insert the sample to be tested in the base tube, so that it touches the inside (lower) Dell ’ ring of the measuring Chamber: You can tuck under to it appropriate spacers;
- You put the measuring Chamber (plastic cylinder and lead supportive ring) so the below sample is centered on the bottom of ’ ring;
- He slips his shirt more than basic ’ inside the cylinder: It will support the plastic pipe and concentric ring of ’ will lead to the hole to allow subsequent insertion of the probe;
- You insert the probe : in my case straight draw in ’ ring of lead measuring nursery.
From the tests I've done this setup reduces background noise for almost 20 CPS to 3,1 CPS
Download this project, complete with more information and pictures:
Thanks for the exhaustive clarifications.
I will keep you informed of any developments
Hello, I’m trying to re-activate a Theremino PMT Adapter V3.3, which I bought some years ago.
If I insert the modified USB stick into my computer it shows constant LED and after a while is starts blinking.
But whatever I do on the PMT adapter box I don’t see any “microphone” input level. I hear the transverter sound in the box. Maybe the PMT connected to the box is broken?
How can I check if the microphone input is OK? Removing the PMT adapter box and touching the contacts of the connection cable between USB and the box does not show any microphone signal.
Please give me some help!
Many thanks, Paul
Please do a right mouse button and translate in your language.
Difficult to understand from a distance. You would need an electronics expert who, with the diagrams and some tools can understand what happened.
I try to give you some advice…
If Windows sees the MIC input that is added when you connect the adapter then at least the USB part works.
When you plug the adapter into the USB Windows makes the right sound?
Perhaps the jack is not fully inserted?
Maybe something happened to the photomultiplier?
Maybe he took a hit and broke the glass?
If you really can't, you will have to send it back to one of us and we will fix it for you for free (provided there are no expensive components to buy back)
thanks for the quick reply. By checking various PMT probes I found out that the problem is not with the PMT adapter but with one of the PMT probes. So everything should work fine from the USB adapter side.
Your “compensation” feature seems to do an excellent job of improving gamma spectra. Can you point me to a description of what this is actually doing?
In https://www.theremino.com/en/downloads/radioactivity in the description of v4.2 it is called “Resolution compensation”. In https://www.theremino.com/wp-content/uploads/files/GammaSpec_ENG.pdf on pg 35 it is called “broadening compensation”. In https://physicsopenlab.org/2016/02/07/energy-resolution-in-gamma-spectrometry/ it is called “Software compensation”.
Are these the same thing? What is it actually doing?
Yes they are the same.
But the MCA application contains also a second method called “deconvolution”.
You can download our MCA app. and all the documentation files from the following pages:
In the following direct links you will find the more interesting file about your questions:
In addition to the “Resolution compensation” our MCA application has a “Gaussian deconvolution”.
The controls of two methods are in two different panels in the tab “Options” of the MCA application.
– The “Resolution compensation” is a simple sharpening algorithm, similar to the image editors sharpening functions. The sharpening is implemented with an increment of the difference from a sample and the adiacent samples. You could also think to it as a derivative function. The used algorithms are explained in the file “Minimizingfwhm”, in the pages 22 to 25. Our implementation is in the MCA application sources, in the file “Class_Spectrometer”, in the function “ApplyFilter”.
– The “Gaussian deconvolution” is well explained in the file “ThereminoMCA_Deconvolution”.
Thanks a lot for the detailed answer. I had found the note on the Gaussian deconvolution. I will study the other docs.
I am trying to modify the 3D sound card adapter, however, they don’t make them exactly like the one in the instructions. Does anyone have the updated instructions on how to modify the audio sound card (perhaps some schematics as well).
If the sound card is different no one can help without reverse engineering your card.
My best advice is to follow the MIC signal all the way to the chip and then figure out where to cut and where to put the components.
I’m sorry but only you (or some of your friends who are experts in electronics) can do it.
Hello Livio, a have a theremino master DIL-V5.
How can I make the Theremino MCA recongnise the signals from USB port of my computer ?
The Theremino MCA only recongnise sinals of the microphone.
Or how can I do to get a analogic sinal on pin 1 and transmit a digital sinal from pin 2.
The Theremino-MCA application only recongnize the microphone signals.
If you do not have the modified sound card, you could use any sound-card with a MIC input, also without modifications.
The noise at the low energies will be more than normal but it will work.
How can I do to receave an analogic signal on the Theremino Master DIL-V5 and transmit to the sound card with a MIC imput ?
thanks for answering me
The Master can not receive audio signals.
You can not use the master for the Gamma Spectrometry.
You MUST use a NaiTl Christal and a PMT tube and then connected the PMT to a PMT-Adapter and then connect the PMT-Adapter output to an audio card MIC input.
A better alternative is to use a PMT_AudioAdapter directly connected to the USB
Call to Lello if you can not build these components.
Lello = firstname.lastname@example.org
Lello seller on eBay = maxtheremino