Also, a final idea. Ni is ferromagnetic, but oxides are not. Magnetic separation is a possibility.
If the oxides only form a thin layer on the surface wouldn't the ferromagnetic grains still retain their magnetic properties?
can
Verified User
- Member since Jan 20th 2017
Posts by can
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Maybe you could try placing a larger piece of metal of the same material together with the powder to see more clearly if the treatment has an effect.
For what it's worth, from what I've seen chemical cleaning (acid bath) is very effective in making at least the larger pieces shiny in a matter of seconds even at room temperature, but especially with small powders it evolves hydrogen gas in the process which you will have to vent away safely.
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I think it could also be a function of the status of the Earth's geomagnetic field; perhaps there are better indicators for the actual signal reaching the Earth than what I might have found.
EDIT: for example, there's a USGS magnetometer in Colorado which measures the magnetic field of the Earth at that location and the data seems to somewhat correlate with the GM counts from your latest run, but it's not perfect; the signal is likely a combination of many things.
https://geomag.usgs.gov/plots/
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The data is here:
ftp://ftp.swpc.noaa.gov/pub/lists/ace/
The files of interest are the ones ending with "_ace_swepam_1m.txt", column "proton density".
EDIT: from a quick check I think the correlation will not be perfect/simple because the data comes from a satellite in orbit at the L1 Lagrangian point, or to put it simply always facing the sun, while your location is subject to night-day cycles.
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It could be a coincidence, but I wonder if it has to do with solar wind density.
http://www.swpc.noaa.gov/products/ace-real-time-solar-wind
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The signal seems to have overall changed less than last time, but I'm not sure if to any significant manner.
EDIT: GM and ROI do still appear to be correlated to each other. Quick graph below.
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That should also eventually work as a background to use for later operations/calculations. If the spectrometer has a channel drift problem it's better to have a background spectrum composed of many different files instead of a single long one, so that they could be individually calibrated and then averaged together.
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To clarify, I'm not showing the 40K count, but rather the uncalibrated channel of the 40K peak. Maybe it's confusing that in this graph I'm showing it alongside the total count value.
In other words, ideally the 40K peak would always be at channel 1461, but during this run it drifted smoothly between channels 1395-1450.
EDIT: you can also easily see it in the raw data for example by comparing PostExp_1.spu with PostExp_10.spu in the Spectrum Techniques MCA Software.
Wouldn't it be odd if the signal variation better visible with the Geiger counter was correlated with the channel drift of the spectrometer?
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I was only interested seeing more clearly what part of the spectrum exactly varies with time, but I can't seem to get useful results.
I think an issue here is that it's not a decreasing signal, it varies up-down over time in a way that doesn't seem completely random.
Here are total counts for every spectrum. I've also added the uncalibrated channel for the 1461 keV peak to see if there is any correlation with its drift over time:
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Spectra calibrated and all in one single document in the attached file below.
They don't seem significantly different than the ones I previously posted: there are still sometimes small narrow peaks on the low energy range visible particularly when a linear scale for the counts is selected (which is not the default view with the Spectrum Techniques MCA Software).
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...unless somehow heating the alumina tube in its current configuration actually causes gamma counts to slightly increase over the background, regardless of the load. It would be a novel effect!
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I went through previous GM data. Hard to say if there's anything at all. The signal does seem to always start low at the beginning of the experiment (see attached images).
EDIT: I also tried looking for calibrations, but for some reason the Geiger counter and the spectrometer were disabled in most cases, except for the pre-calibration for the first experiment ("Round2"), performed around mid-March:
Since this seems to show an increase of about the same order of that seen in other experiments, I guess it has to be due to a variation of the background signal or some effect related to the temperature, as it appears to start low here too.
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Yes, unfortunately the signal at the spectrometer barely rises above the average. There are odd small peaks sometimes arising in particular in the low energy part but it's hard to say whether they're anomalous at this point.
Below is attached a final multipage graph of the entire experiment.
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Since I had little idea of what I was looking at, I thought it was older code (EDIT: eventually, I found it was almost 5 weeks old code).
The spectrum above (as well as those in the attached document) isn't averaged, although in the previous deleted comment I posted one containing average-subtracted data. I recalled that this was done last time but I didn't give much thought as of why. Of course one would actually want to subtract the background.
So, that's what I've done in the attached file below, using the first spectrum in the series as the background. The result is a bit noisy and probably not too useful, however.
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Using old forgotten code (thus magic code), I've made this. It could have some additions (e.g. average subtracting) but it's a start. The pdf documents contains other calibrated spectra.
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I can replace zeroes with the mean of the series, that would remove some of the noise.
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The change in GM counts (in particular) seems interesting. I've made a dedicated graph of its data resampled to 60 second bins, which makes the trend over time a bit more clear:
In addition to the graphs updated hourly on the shared folder on mega.nz (last 14 hours of data plotted), below is attached an additional multipage plot with the latest data since the beginning of the experiment.
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If it helps diagnosing the issue, I'm using Firefox 53 64 bit.
Here are ROI and GM counts since the start of the experiment in a standard image format. There is indeed a rise where you indicate, but there seems to be one earlier too: