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U-238 Let's walk through Uranium Radioactive Decay Schemes, one U isotope at a time to clarify the reason we see certain peaks on spectroscopy scans. We use the convention in this science that: X-Rays are generated in the electron shells of atoms. Gamma Rays are generated in the nucleus of atoms. Regardless of their energies. U-238 is the most abundant isotope of uranium on earth. It's total decay scheme ends in Pb but we can break the whole down into smaller groups of decay chains that may or may not be included in the samples we study. An easy example is the Radium decay chain. Radium has been separated from raw Uranium ore for a long time now. Even longer, the U-238/U-235 decay chain has been separated from rocks by mankind, the most obvious practical use being for making pretty colored pottery glaze (not just red either- different oxide states can make ivory and black). This kind of separation is chemical and the processes can easily differentiate Uranium from Lead daughters for example. Simple separation cannot tell U-234, U-235 and U-238 from one another, so in all chemical types of processes the preexisting mixture of isotopes remain in the same ratio. In the study of Trinitite we know a few things about the Uranium that was used in the Gadget, for example the tamper was made of natural uranium metal, so it had a normal complement of U-235. Some scientists calculate that 30% of the total yield came from U-235 fission, so we can expect the natural radio to be altered. in the remains. If we had a perfect sample of depleted uranium to test, it would have started with pure U-238 and the decay chain would be simple: As illustrated, the U-238 is present in the greatest numbers in the sample, but daughter products immediately begin to build up. First U-238 decays to Thorium-234 by Alpha Decay. Let's examine this first decay in detail. A particular atom of U-238 decays by expelling an Alpha Particle at great speed. The nucleus of that atom has instantly lost 2 positive particles and 2 neutral particles. At that instant the Alpha Particle takes off in some direction, and because it is going so fast, the remaining nucleus goes off in the other direction, the speed of which travel if in a vacuum would be a simple ratio of the mass of the two components (4 and 234). Sometimes this motion is probably fast enough to expel some outer electrons from the remaining atom, which at this time is already a Thorium-234 atom. Now lets discussed this newly created Th-234 atom. It's pretty much the same as all the other Th-234 atoms but not identical because it must rearrange it's nucleus and electron shell before it can be a proper daughter. While doing this, it spits out unneeded energy to stabilize the nucleus (we call some of that energy Gamma Rays) which must of course interact with the electron shell area as it exits the atom and tries to find it's way to our Geiger Counters. Of these interaction with the electron shells, a certain number of them will generate a displaced electron, which of course must be replaced, leading to what we know as and XRF X-Ray, which we also want to find our sensor array for identification purposes. Many other interactions happen during this process but we don't need to consider them in this discussion. The take-away is the a U-238 DECAY makes a specific X-Ray come about from it's daughter. The XRF energy is NOT of a Uranium atom, but it's Daughter atom. Contrast this to the actual Uranium XRF X-Ray that is elicited by external excitement of U, which is the actual Uranium XRF- these are two different and very distinct energies. So it's clear to look for U-238 we have to look for Th-234 and Pa-234 Gamma Rays and especially XRF X-Rays. There is one more Uranium atom to come out of this U-238 decay in fairly short order, the U-234. Notice the extremely long half-life T/2 of U-234. It is actually the head of a distinct decay chain but for that chain to reach equilibrium again, it will require centuries to go by. What's important to realize is that this is the ONLY Uranium being created in this Decay Chain, th

https://www.ebay.com/itm/Kevex-KM12506SW-Micron-Laboratiry-Radiography-Imaging-X-Ray-Tube-T82946/352998956048?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 Well, I should've thought more before making offers, right? Looks like a nice one though and up to 125kV, 10W tube. Any thoughts? -- Nick A

I had a CT coronary angiogram today . I think a fairly high dose of iodine contrast dye was injected intravenously via an automatic syringe pump . I don’t remember any technician reminding me to drink plenty of water following the procedure . About 12 hours later I realised my mistake I took a sample of urine and did xrf analysis using Rap47 and Am241 for iodine. I also have a sample of the same iodine dye in my possession for comparison Urine looks concentrated Urine xrf show iodine peak For the sake of completion ,I am showing my urine and iodine dye pic For the iodine to show up in the urine xrf ,it has to be in fairly high concentration This was 12 hours later Drinking lots now and getting close to midnight This proofs to show home xrf has medical lab use too ..for certain substances at least. I will monitor my urine iodine elimination for future reference. Taray

Xrf burnt bulb Using Rap47 and Am241 exciter 15W bulb ..not 15 tungsten bulbs... 20x54 mm The xrf was done in a lead castle large enough to prevent scatter from the shield A tungsten metal plate used as a reference No glass was shattered during this test This is one of my rare good pics Taray

Several MCA8000A versions are showing up on eBay. It should be understood that these are not complete MCAs, like a Spectrum Techniques UCS-20/30 or an URSA2. The sections lacking are the front end electronics and HV bias supply, namely the sensor preamplifier and the shaping amplifier, and HV generator. The input to the MCA8000 is a trapezoid, not a sharp pulse such as from a PMT and the level is TTL (I think), definitely not low milliVolts. The MCA8000 is designed to work with a power supply/ shaping amplifier unit between it and the sensor/preamp package, such as the PX2 series. So a typical setup is an XR-100 detector box containing just the sensor and preamp, then the PX2, the version specified for the type of sensor in the XR-100 (i.e.Si-PIN, CZT, CdTe etc), then the MCA8000. In this lineup the PXT provides the HV Bias to the sensor and all the various low Voltages that are required by the preamplifier module inside the XR-100 head. In the PX2 these are not programmed by a computer, but rather by a technician, indeed the PX2 does not have a computer port on it, that is only on the MCA8000. Notice that the MCA8000 does not supply HV or any other support to the sensor box, . AMPTEK does make a version of the MCA8000 that is set up for PMT based systems, but it has the several expensive additions, and in my opinion is not too practical, although one would be great if the price were not so high. Si-PIN PX2 power supply/shaper amplifiers can provide only 110V HV. The PX-2T can provide up to 500V and is the one to use for CZT/CdTe, although they actually require 600V and above, so again, not ideal. What I'm still looking for is a comprehensive list of sensor model numbers that tells what's actually inside there. Until we have that, we don't always really know what is being offered on eBay etc. by sellers who obviously know way less than we do about the subject. Geo

5V and USB cable to your laptop. Amptek inside. Runs on DPPMCA program.

All protective caps used on AMPTEK and similar solid state sensors MUST be ventilated. An unventilated cap tends to draw a vacuum if removed quickly, putting stress on the sensor's thin beryllium window. See pictures of some Red Caps that I make and use. The Red Cap is first punched with the vent hole, 1/8" is ideal. Notice one cap has a really large hole punched in it. As it is, it can provide some protection to the sensor, but when paired with a special Kapton Tape accessory, it is very much more protective- see the Kapton discs, themselves punched with a 1/8" central vent hole. FYI I have one complete ready to use GEO-1-2-3 left for sale. Geo

The AMPTEK PCB DP5-PC5 use a HIROSE MQ series power connector. This connector is really small and cr4azy expensive. It's hard to work with and attaching large or regular sized wires is nearly impossible. I made an adaptor that transitions a HIROSE to a 5.5 X 2.1mm coaxial power connector for the test bench. This makes it easier to make current and Voltage tests using existing homemade testers. The 26 AWG solid silver plated wire with Kynar insulation fits the HIROSE pins perfectly and is rugged by design. The small circuit board is a home made HIROSE polarity tester. It's good to be back at the workbench. Geo

Charles, Looks good. Note that the Au “peak” is really just noise(4 counts). Its good to have the Am and Np tags turned on to save time when doing energy ID’s. You don’t need to scale up the graph to see small peaks just switch to the Log Y plot. It will show all the peaks and enhances the low count peaks. Ok it’s not as pretty and doesn’t have all those tall sharp peaks everyone seems to like, but it has much more information in it and is the only way to look at spectra when interpreting what you got. Look at the Silver dollar raw spectra plotted in linear space. The low energy instrument noise dominates the spectra with over 4500 counts and all you can see is the Ag peak with 227 counts. Switch to Log space and everything is seen. I might point out the MCA was spending most of its time counting the low energy noise below 1 keV. The lower limit discriminator (LLD %) should have been set to cut out this noise to improve the count real time it takes to get a peak defined. Look at the terra cotta spectra in log space then you’ll see the weaker high energy peaks displayed much better. Dud From: [email protected] [mailto:[email protected]] On Behalf Of charlesdavidyoung@... Sent: Tuesday, April 14, 2020 6:07 AM To: [email protected] Subject: Re: [GammaSpectroscopy] Terracotta Floor Tile Mike, you might scale up the graphs and let the large peaks go off the top. Then we might be able to see the 2.6 peak better. Dud, here is the scan of a silver dollar that has both Ag and Cu. I scaled it up to allow the Am241 reference peaks to be more clearly visible. Charles

I have an interesting specimen from the Spinelli Prospect in CT. It is similar to other specimens reported from this locality. https://www.mindat.org/gallery.php?loc=4565&min=1514 Even though this appears to be one solid crystal there is a distinct difference from front to back. The front is a subhedral columbite-Fe crystal with distinct faces. The back not so much. Along the edge there is a fracture that transitions from hackly to conchoidal as it goes from columbite to samarskite. Finally, my XRF of both sides shows that the columbite has no Y to speak of whereas the samarskite side has lots of it. Many of my specimens are mixtures of minerals but usually not so distinct. Charles

Based on Dud's encouragement I will try and use DppMCA for analysis. To be clear, I tried it previously when I first got the Amptek system and got discouraged. I'll give it another try and document it in a subsequent email. First though I wish to give a quick demo of how I use DppMCA for acquisition and Theremino for analysis. I will make it as simple as possible. I will both embed the images as well as attach them because some people have better luck with one or the other. If you download the attachments and put them in a folder you can scroll through the images as I describe the steps. Step 1: acquisition The target is a small specimen that has some nice little fergusonite crystals associated with zircon cyrtolite. Because it does not present the ideal geometry it took an overnight run to collect the data. https://www.mindat.org/photo-962547.html Step 2: import into Theremino I modified Theremino to recognize the .mca format and import the data with no processing other than to draw it on the screen using the available resolution. Step 3: turn on reference labels Because of the Am241 source and its shielding there are many peaks that I wish to be aware of so that I can ignore them most of the time. This creates some temporary clutter but it allows me to quickly determine which peaks are really of interest. Step 4: zoom in on region of interest It is immediately apparent that there are 3 large peaks that don't align with any of the reference peaks. I zoom in on those to reduce the clutter. Sometimes we are not so lucky such as the case of Fe which is present in the Am241 button. In this case I am pretty sure it is not a major element of the specimen. If the Fe peak were much larger I would assume differently. Step 5: identify the Nb peak I use my mouse to double click on the largest peak. The id label NbKa1 appears over that peak and the NbKa2 and NbKb1 labels appear at the same time. Having these labels toggle on and off as a set allows me to quickly evaluate the validity of an id. In this case all 3 peaks look reasonable so I will assume with confidence that Nb is present in this mineral. Step 5: identify the Zr peak I double click on the next highest peak. Once again all 3 peaks align nicely with Zr, even though the ZrKb1 label is a little obscured. I'll clean that up later. Zr is definitely also present. Step 6: identify the Y peak I double click on the last large peak and the Y identity labels appear. The YKa1 and YKa2 peaks line up precisely so this is also looking good. The YKb1 peak is a little more subtle because it is so close to the NbKa1 peak. They are so close in fact that when both Nb and Y are present their peaks add together to make an extra large peak. The presence of the YKb1 peak is betrayed but the bulge on the right side. Once again I can say with confidence that Y is present. Step 7: declutter and document There are no other major peaks of interest so I can turn off the reference labels and document my results in the text box on the left. This whole process took perhaps 2 or 3 minutes. Luckily I was able to identify all the elements necessary to justify this mineral identity. Typically there are many other elements present and it can take a little longer. If the elements don't match the mineral formula very well further research is sometimes necessary to clarify the id.

The scan is of ishikawaite from Little Patsy Pegmatite, South Platte, CO. The Si-PIN is sitting on the window sill with a view of the Catalina Foothills. Charles

In my collections are a half-dozen unusual Trinitite samples. This series will examine them using all the tools currently available in the Home lab. Various sensors will be used, as well as a few Spectrum Techniques calibration sources, including Fe-55, Ba-133, I-129, Cs-137, Co-60 as needed. This first picture of a scan is perhaps my most unusual Trinitite item, labeled as TM for this series. Using Gamma Spec, it will be compared to RT (Red Trinitite) and GT (Green Trinitite) First a picture of the 24 Hour scan of TM alone on an Amptek CdTe sensor in a lead shield. Full range of this sensor is 0-411 keV and covers the main region of the spectrum currently being studied. Other sensors will be used to add to the information base to take full advantage of their unique capabilities. Each stage of the process is stopped in time when a particular peak in RT is equal to the corresponding peak in TM and recorded, allowing for frame by frame comparison of the similarities and differences between the two samples. Shown here is TM, first alone, then compared against RT(Red Trinitite) in posts to follow. Peak Search a feature in Amptek's control program for the sensor easily picks out the obvious Am-241 and daughters, Uranium L-Shell X-Rays, Cs-137, and Lead (Pb) Ka and Kb X-rays. We'll pay particular attention to Europium (Eu) traces as well. Geo>K0FF

Steve- here's the data on the two Zircons, (for some reason my eMail won't attach them). Geo

Hi guys This is my X-ray setup My x ray generating tube sits within a cylindrical X-ray collimator This collimator protrudes into a cardboard box containing my X-ray detector and X-ray signal detecting Inspector Usb Geiger counter. The exit of the X-ray collimator is closed by a less than 0.5 mm Al sheet The back is a leaded glass with lead polymer sleeves ..to prevent backscatter from the rear and of my collimator My X-ray generating tube is placed in such a way that the cathode is closest to the exit of X-ray beam Applying the anode heel effect. I chose a low Z element Cr about 4 by 2 cm approx for xrf and titanium orthopedic implant. Since my tube is not an x -ray tube ,it will not tolerate continuous firing So I did it with intermittent shots each lasting about 1 sec Probably a 70 kvp will be more damaging than a 30 kvp like in my setup You notice a polymer covering for almost everything This is a probably antimony polymer from some old stripped medical X-ray aprons courtesy of a hospital where I work.The X-ray glass was also surplus from my hospital . Should be sufficient to block 30 kvp X-ray Using multiple layers of apron material just in case. Pics are for my setup,transformer and an exact replica of my X-ray collimator and a Cr and Ti pic Apologies for not showing the X-ray generating tube. Taray

Thanks to member Steve D. in ALBQ NM for mentioning that Zn ores are also a common source of Cd. Testing several species of ore here with the new emphasis on Cd has proved problematic. First the X-Ray hump from the tube is most intense right where Cd K line XRF is located, making it harder to pick out a weak peak there. Strong K peaks- no problem, as shown in one of the pictures to follow. So I tried looking for L peaks from Cd in ore. First steps are to use pure Cd metal to establish calibration points exactly for 3.2, 3.13, 3.31, 3.52, and 3.71kev. Then another XRF test of the empty chamber, with no samples inside, for the same time and exposure data. In all tests for this series, the 3 Al beam filters remain but the final collimator is removed to give a wide beam on the mineral tests to follow. The detector is an Amptek Si-PIN into the Amptek DP5-PC5 electronics stack, then USB to a notebook computer for control and storage. First the pure metal "stamp"r, X-Ray source set to 37kVp-25uA In the above, Ka, Kb are in perfect alignment and something is barely detected around 3 keV This rendition (LINEAR) shows how well the K lines are excited in the lighter elements, compared to their L lines. Geo

Pre-WW2 U02 ceramic glaze. Geo

Radioactive Zinc ore. Pictures to follow, here is the Gamma Scan on Si-PIN Geo

25mm diameter but 10mm thick, and much heavier than a normal test disk.