Xrf meteorite
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taray singh
Hi guys Here??I have a meteorite specimen I bought from eBay more than 5 years ago .It was sold as a Zag meteorite which hit Moroccan Sahara in 1998. Apparently there many episodes of meteorite falls there which go undeclared. Perhaps that is why I got it. It weighs about 7 gms and about an inch wide . I??really think it is not a ¡°meteorwrong¡± cos 1 Brown crusty outer layer due entry into earth¡¯s atmosphere with a lighter shade within . 2 It is quite magnetic for its small size Furthermore it¡¯s looks very similar to samples on the net .Possibly a??H3-6 Breccia. I believe it is a stony iron /nickel silicate minerals consisting of free iron/nickel??and silica among other elements? I examine it under a light microscope which show free metal interspersed with rock .Due to the 3 dimensional nature I focused on selected areas only Only a thin section will reveal more . There could also be some halide compound within??but I am not able to visualize it My xrf analysis with Am241/Bicron X-ray detector show iron??consistent with my magnet and light microscopy Gamma spectrometry was??negative probably due to the small size .Meteorites can be radioactive??though? Thank you Taray |
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On Sun, Apr 19, 2020 at 02:19 AM, taray singh wrote:
Gamma spectrometry was??negative probably due to the small size .Meteorites can be radioactive??though?Taray, Very interesting.? Did you get any rate over background in your shield?? Did you try with a scaler and a pancake? A statistical analysis might be required. I have read that meteorites have little radioactivity because the processes that concentrate U and Th have not occurred like on earth, even with "differentiated" types. It would be fun to look for it though! Mike L. |
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Hi Taray, If you could let that run about 10x longer we would have enough counts to know for sure whether there is something else in addition to Fe.? I would be interested in seeing that mca file again after that. BTW, 1024 channels is really not enough resolution for seeing everything.? I tried that for a while and it makes fast, smooth scans but I was missing a lot.? I now run 4096 channels and just wait for my largest peak to get to about 200.? BTW, I also changed my gain to 9.999x. Charles On Wed, Oct 21, 2020 at 5:23 AM taray singh via <sukhjez=[email protected]> wrote:
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Charles, what is your peaking time? I've been using 4.8 us but may change it to slightly slower to get rid of all noise on far left. Geo From: "Charles David Young" <charlesdavidyoung@...> To: "XRF" <[email protected]> Sent: Wednesday, October 21, 2020 7:46:09 AM Subject: Re: [XRF] Xrf meteorite Hi Taray, If you could let that run about 10x longer we would have enough counts to know for sure whether there is something else in addition to Fe.? I would be interested in seeing that mca file again after that. BTW, 1024 channels is really not enough resolution for seeing everything.? I tried that for a while and it makes fast, smooth scans but I was missing a lot.? I now run 4096 channels and just wait for my largest peak to get to about 200.? BTW, I also changed my gain to 9.999x. Charles On Wed, Oct 21, 2020 at 5:23 AM taray singh via <sukhjez=[email protected]> wrote:
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I'm using the same peaking time. El El mi¨¦, oct. 21, 2020 a la(s) 7:14 a.?m., <GEOelectronics@...> escribi¨®:
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Thanks, Geo.? This is a good example of why it is important to have enough counts.? The one with 200+ counts shows a clear Ni peak.? The one with a count of 100 is showing signs of Ni but without a higher count it is hard to say. Charles On Wed, Oct 21, 2020 at 7:09 AM <GEOelectronics@...> wrote: .mca of my small Fe-Ni? and the one that to the eye is "stone" |
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Charles,
I tried a magnet on one of my Am241 buttons.? It was weakly magnetic.? Assuming it is Stainless Steel, this points to an Austenitic class (like 304 or 316) and that means it has both Cr and Ni in the composition.? 304 is around 18% Cr and 8% Ni , 314 is about the same Cr, but 10-14% Ni with a little Mo thrown in.? There are others, but these two are very common.? I don't know if you would see Ni interference with a long Am241 scan or not. Strongly magnetic stainless steels are a Ferritic/Martensitic and have Cr but no Ni.? These are 400 series, you see this used often in knives. Mike L. |
¿ªÔÆÌåÓýShort peaking times are used for high count rates and with Pile up rejection and you trade off resolution for count rate. A longer peaking time is used for low count rates for better resolution but with a slower acquisition time. When changing peaking time you need to also reset the slow and fast thresholds to optimize to your system or you¡¯re still going to get low energy noise or missed counts ?That can be done manually or automatically in DppMCA. The DP5 system must also be set up with the actual specifications of the detector you are using so be sure to check that if it¡¯s not a factory supplied DP5/SI-pin pair. That setting is in the DPPMCA. The gain setting is going to set the range of interest and to a certain point the resolution which is limited by the FWHM resolution of the detector itself. Over sampling will do nothing for resolution but will increase the acquisition time by a factor of 2 for each doubling of conversion gain. Even SDD detectors only use 2048 channels.? Running a high count rate with the wrong peaking time will cause pile up problems loss of resolution and energy shifts. Watch your dead time and the Total and Input count. They should be close to one another. If total count is too high you have too much low threshold noise and need to optimize the system again Am sources need a long count time to see much of anything other than % level elements 10 - 20 counts isn¡¯t a peak, it needs lots of counts and a Gaussian shape to see if its merged with other peaks, has a low energy tail, and to find the true centriod. Dud From: [email protected]
[mailto:[email protected]] On Behalf Of Charles David Young
Sent: Wednesday, October 21, 2020 8:37 AM To: [email protected] Subject: Re: [XRF] Xrf meteorite ? I'm using the same peaking time. ? El El mi¨¦, oct. 21, 2020 a la(s) 7:14 a.?m., <GEOelectronics@...> escribi¨®:
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FYI- All the ones being used here are factory matched DP5-PC5-Si-PIN. These are made from the OEM kits. Geo From: "DFEMER" <dfemer@...> To: [email protected] Sent: Wednesday, October 21, 2020 12:04:38 PM Subject: Re: [XRF] Xrf meteorite Short peaking times are used for high count rates and with Pile up rejection and you trade off resolution for count rate. A longer peaking time is used for low count rates for better resolution but with a slower acquisition time. When changing peaking time you need to also reset the slow and fast thresholds to optimize to your system or you¡¯re still going to get low energy noise or missed counts ?That can be done manually or automatically in DppMCA. The DP5 system must also be set up with the actual specifications of the detector you are using so be sure to check that if it¡¯s not a factory supplied DP5/SI-pin pair. That setting is in the DPPMCA. The gain setting is going to set the range of interest and to a certain point the resolution which is limited by the FWHM resolution of the detector itself. Over sampling will do nothing for resolution but will increase the acquisition time by a factor of 2 for each doubling of conversion gain. Even SDD detectors only use 2048 channels.? Running a high count rate with the wrong peaking time will cause pile up problems loss of resolution and energy shifts. Watch your dead time and the Total and Input count. They should be close to one another. If total count is too high you have too much low threshold noise and need to optimize the system again Am sources need a long count time to see much of anything other than % level elements 10 - 20 counts isn¡¯t a peak, it needs lots of counts and a Gaussian shape to see if its merged with other peaks, has a low energy tail, and to find the true centriod. Dud From: [email protected]
[mailto:[email protected]] On Behalf Of Charles David Young ? I'm using the same peaking time. ? El El mi¨¦, oct. 21, 2020 a la(s) 7:14 a.?m., <GEOelectronics@...> escribi¨®:
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On Wed, Oct 21, 2020 at 07:23 AM, taray singh wrote:
Taray, Yesterday I received a 11g, Canyon Diablo (Barringer Crater) iron meteorite.? I have been looking at it with a new Am241 exciter that Charles Young and I have developed. I am not ready to present my spectrum yet, but I now know that the three lines to the immediate right of you main? iron? peak are Fe Kb1, Ni ka1, and Ni Kb1.? My spectrum looks similar to yours.? I think Canyon Diablo meteorites are 7% nickel. Mike L. |
Mike L.
