Cameca unshielded EPMA production cessation

[Probeman]

So I guess I am not sure why these things have happened if there has been "zero incentive for innovation in the electron probe market for decades now".  Cameca, from Claude Conty on down, were very excited to try to do something really new and innovative in WDS when they committed to the SX-Ultrachron project.  I agree there is plenty more to do going forward, at least from our point of view, but how to make these happen is the question.

My sentiments exactly!

I suggest we compile a list of improvements that we all would like to see and submit them to JEOL, perhaps at M&M this summer and also to JEOL Japan.

If we do this as a community it will have more impact than a few solitary voices.
john

[Nicholas Ritchie]

Mike is right.  The correct number isn't zero and he has played an important role in many of them.

[sem-geologist]

We run WDS full section maps in order to find all of the monazite and xenotime (sometimes zircon) in a thin section.  Two maps overnight.  300nA, 15kV, 35um beam, 20ms pixel count time.  Typically, we use Ce La as the monitor for monazite.  We will set up elements for base maps to evaluate texture and petrologic context for these accessory minerals, and that includes several major elements from EDS channels (the integrated Bruker XFlash 610H on that machine).  The latest set we received for someone they warned us that the thin sections were prepared with Ce-oxide as a polishing compound.  When we know this, we switch our monitor element for monazite to La La on WDS PET, which is a bit less abundant compared to Ce in most monazite, but works fine, no problem.  As an experiment, we thought we would also monitor Ce by EDS to see if the Ce-oxide actually showed up.  In all of these maps, we got the usual nice bright La spots in WDS maps, but the Ce EDS maps saw maybe 10% of those if I am generous.  Maybe we could do better if we open the aperture all the way, but this gets into a very high dead time area for majors. Anyway, for us, the signal to noise difference WDS to EDS is not even close.

That's quite extreme conditions for prospecting I would say. Our SEM-EDS workflow can achieve detection of monazites at 1um scale, and with much smaller irradiation of the sample (dwell time of 8-16us). The secret sauce is that for mineral discrimination we use mainly 16bit BSE - and EDS is only a secondary discrimination. There we use some clever multiplication of intensities (i.e. Zr will be highest intensity of Zr La * Si Ka than any other mineral) and division (to exclude some overlapping EDS of minerals where absence of element is more important). I lately am experimenting on fitting the real spectra for mineral classification. We also need to distinguish Allanite, Prerierite, Chevkinite alongside Monazite, Xenotime. For REE we use sum of all REE (La, Ce, Nd) and that then allows to solve some ambiguities (like La-Ti EDS overlap).

The interesting bit of news to me is that the SKaphia will remain in production.  Given that the Skaphia is an SXFive at it's heart, with some added stuff, that means that all the tooling and human talent to make SXFives will still exist in the company.

Something strange is going on here, unless I'm vastly underestimating the costs involved in keeping the production of the shielded systems going.  All the tooling and talent for making whole microprobes will need to be preserved internally in some way to support the shielded line, and we may yet see a reemergence of the unshielded systems in some form.

Exactly, Maybe they are only pausing the SXFive production. The good thing is that if it is very similar maybe there would be no real EOL for some parts, in particularly for detector windows and separation windows which are quite crucial.

I asked Cameca if they were planning on releasing their API to the community for us to continue development on the machine but they have no plans for it at this time.

I think that would be not enough. That alone would not preserve continuity of these machines, we need source code of firmware at least. So that we could make replacement boards if needed. API alone is just delaying the death of machines.

BTW, good luck with Your new carrier, I find myself being tempted (especially my wife is encouraging me to do that) to change career into something much more profitable.

The Tactis platform has integrated Bruker EDS to a truly full integration that get to the previously stated 'holy grail' of mapping: WDS with EDS hypermaps to be able to extract EDS elements in full mapping quant analysis, this is still being improved...

Do You have Tactis, is it possible to obtain Bruker Hypermaps with stage and not beam scan? I know that SXFive can be upgraded with that option, and wonder if it is worth it (We have 3 SEM where we can do hyperspectral mappings (Bruker detectors), with much higher throughput at much lower beam voltages, but only with beam scanning, thus asking this here)

I agree with Mike that Cameca has done a considerable amount of innovation (large area crystals also being an important one) over the last 10 to 15 years, but I think Nicholas' point is that with Cameca now (mostly) not selling microprobes, those innovations will essentially fall by the wayside.

Looking forward can we expect JEOL to start innovating more?  I don't know, but let's try and list a least 10 ways JEOL could improve their current microprobe. I'll start:

1. Implement solid state detectors for WDS spectrometers
2. ...

solid state detectors... again. Can't understand that obsession. It would make sense only if diffraction crystals would be focusing to point and not line. As Solid state detectors are round. The G(F)PC has few key advantages for being used in WDS:
    1) The active volume where X-rays can be registered is very narrow cylinder around the biased wire. That allows more simple diffraction crystal manufacturing process and peak is not blurred by large detection area (which large SDD would do). The active volume is used in its fullest. For SDD It would need some "line"-like aperture in front, so only very little fraction of active detector surface would be used.
    2) Cooling. G(F)PC does not need that. SDD working at room temperature and higher would have comparably terrible resolution.
    3) solid state detectors produce unnecessary spectral artifact like tails i.e. with incomplete charge collection. Si Ka escape line kicks in with lower energy lines than Ar Ka escape (or Xe escape). It is in particular important for Pb, Th, U in geochronology where Silica detector would introduce artifacts which are not on GFCP.
What I propose is combining advantage of G(F)PC with advantage of SDD (or more precise learn from advantages of current solid state detector counting electronics). Currently implemented GFPC counting is very strongly affected with pileups and does not allow to filter out 2nd order lines fully. current PHA is passive dumb PHA. That is like selecting regions for mapping on EDS for overlapping peaks (i.e. Zr La and P Ka; SKa and Pb Ma). But that problem (EDS mapping) already was solved a decade ago with introducing of deconvolution method! That is the main missing point for total WDS PHA empowerment. Currently PHA is set like those old time EDS maps at baseline and window size - the region of histogram. But PHA curve could be collected during counting and saved like EDS spectra for later treatment. Currently integral and diff counts are preserved at WDS board during and after counting. With such curve preserved the exact window, or with deconvolution by fitting Gaussian curve the precise part of counts corresponding to selected measured line could be much more precisely quantisized. Also this would allow to have much better peak-pile up correction than what EDS normally have by utilizing deterministic fixed dead time (as currently is). Actually we don't need much shorter deadtime (shorter deadtime means shorter shaping time and it comes at cost of worse energy resolution). SDD does not have much shorter dead time and still can cope much better with higher count rates than WDS. (i.e. 1Mcps)

Do not underestimate solitary voice and capabilities of a single person. I guess Probesoftware was also born into what it is with single-man effort at the beginning? Am I wrong?

[John Donovan]

Do not underestimate solitary voice and capabilities of a single person. I guess Probesoftware was also born into what it is with single-man effort at the beginning? Am I wrong?

I agree we should never "underestimate solitary voice and capabilities of a single person"!   But in fact Probe Software has never been a "single-man effort".  In fact, our company has benefited from employing, collaborating and consulting with many experts in (and outside) the field.

The Help | About... dialog in all of our applications provides a partial list of our collaborators and this is a list of our current consultants:

https://probesoftware.com/Support.html

[Mike Jercinovic]

Do You have Tactis, is it possible to obtain Bruker Hypermaps with stage and not beam scan? I know that SXFive can be upgraded with that option, and wonder if it is worth it (We have 3 SEM where we can do hyperspectral mappings (Bruker detectors), with much higher throughput at much lower beam voltages, but only with beam scanning, thus asking this here).

Yes, we do have the Tactis.  The first one delivered anywhere.  Bruker EDS is fully integrated, such that, yes, hyperspectral maps can be collected by stage by stage or beam.  Peaksight handles it either way, so in the Peaksight image processing, you can extract whatever you want from the hypermap.  Of course you can also bring in the hypermaps into Esprit if you want, but Cameca works with the Bruker input just fine.

[sem-geologist]

There is no reason that SDDs need to be round.  In fact, many aren't.  Custom SDDs could be designed to enhance throughput at reduced resolution with better matched shape.

You are right, I could not find an example previous, Today I came across this so I am going to leave the link below:

https://www.hitachi-hightech.com/hhs-us/product_detail/?pn=ana-vortex-me3

The detector itself and form factor is irrelevant, but existence of such shape of SDD is promising for our cause.

We would need solid state detector with 4 cm length, where width should be 2-3 mm max:
  1) That is more less the 2R of cylinder of active volume of G(F)PC, and so the solid state detector should contain not larger width to not introduce the worsening of spectral resolution achieved by diffraction.
  2) while it would be possible to add the aperture in front of solid state detector, the blanked portion of detector would still require cooling - narrow solid state detector would require less cooling.

With PIN detector You can forget about sub 1µs dead times, it requires few to tens of µs shaping time to get something sensible. SDD is the only detection technology currently allowing to gets anything sensible with sub 1µs shaping and going > 2Mcps in input count rate.

Interestingly AMPTEK recently added to its portfolio thicker SDD (1mm) which has extended efficiency past 10keV (That would be really good for LiF range), with no impact for lower energies.

But I really wonder if G(F)PC could also not go easily to >2Mcps with better charge sensitive preamplifier and faster Shaping amplifier.
What about debris from moving parts (from this rotating screw moving the assemblage of turret) - the construction and maintenance of G(F)PC is much more simple and possible to DIY (basically changing counter windows), where fixing or cleaning of solid state detector (and It fails unexpectedly, i.e. from 8 SDD EDS know to me 5 had to be sent back to manufacturer for fixing in 4 years from installment, with downtime of more than 2 months) is requiring sending it back to manufacturer.

Downside of GFPC is the gas. But how much bottles are bothersome for machine anyway being fixed at room and not being portable? We are changing bottle of P10 gas which supplies gas to 5 spectrometers of SXFiveFE about every 12 months. It is important to check for gas leaks at junctions, as that can significantly slow down gas bottle getting empty. Is it really so bothersome to change gas every 12 months? It can be bothersome if bottles are in different room with worse air conditioning, and bottles being attached to wrong (thermal unstable) wall, the thermal seasonal temperature variations will show up in PHA. However if bottles are at the same room (as probe), situated by inner wall (thermally stable) and room has good AC, then the observed PHA shifts due to seasonal temperature, pressure and humidity will be visible at some small degree only on low pressure GFPC.

PHA seasonal shifts (like atmospheric front pass over geographic area/campus where probe resides at summer) could be overcome with automatic bias gain readjustment in software. It could be enough to add temperature humidity and pressure sensors to initiate such readjustment in case of condition changed. But wait a moment - from my experience SDD are also affected by atmospheric front passing. I saw many times that EDS needed re-calibration after that, so moving to solid state is not going to fix that problem, but getting precise dehumidifier for room would be more beneficial.

The only real benefit moving away from G(F)PC I see is for FEG machines, where silent little Argon leak from counter can silently contaminate the simple diode ion pumps and then unexpectedly do boom! - Your pricey FEG tip just got ruined. But actually even there after experiencing such events once, now I am confidentially sure to be able to detect such event by monitoring vacuum of both ion pumps, where secondary pump will hint of that very early enough to be able identify and fix the issue.

Finally, do we really need sub-µs shaping time (dead time)? SDD EDS have that... but there live time is estimated, not directly measured compared to G(F)PC with fixed time signal blanked/fixed dead time. The first is worse estimated with high impulse count and with increasing dead time (pulse density), where GFPC counting with fixed blanking dead time has no paralysable behaviour even with very high count rates (I know that somewhere here in forum was written contrary, but that is due to wrong calculation of dead time at differential settings and unaccounted pile-up, which BTW is going to be fixed in next Cameca Peaksight 5.6). Also SDD EDS dead time estimation is really bad (imprecise in few orders compared to current GFPC counting implementation) for very short counting times. I think it is much more important to have no paralysable behaviour AND very precise dead time/ live time measurement (not mere estimation, with blocking behavior what SDD counting electronics have) – even if we get sub 1Mcps but having very precise live time estimation that would allow to estimate precisely input count rate even above 2 Mcps. I think for any quantitative work that is much more important. Telling that, I think it would be possible to improve the current WDS throughput and linearity and PHA stability significantly with not touching detector design at all and improving/replacing only analog amplification and counting electronics.

P.S. I nearly finished gathering factual pieces, and soon am going to open new thread in this forum showing currently used counting technologies and solutions by Bruker and Cameca WDS (measured stuff), AMPTEK, CREMAT published and available hardware. To go with improvements, we should first fully understand what are exact shortcomings of currently used technology (but also what are advantages), and what consequences would be by technological shift. (it not always brings in progress, but can bring unintended regress which in some usage cases can be crucial). The shortcomings in software/firmware of current technology is often overlooked, the lack of possibility to discuss the hardware (no schematics, or schematics provided to end-user with strict NDA clause) freely is one of main obstacles. I.e. there is this new thread about dead times of WDS. I could not convince anyone there why dead time is calculated wrong at widely used diff mode, and I am still not sure probeman had understood me correctly in numerous exchange of replays in PM. Contrary to that, I could easily convince there is error in diff mode dead time calculations the Cameca Software engineers by pinpointing/describing to exact place in schematics with a single e-mail, and that is going to be fixed in next Peaksight release (5.6). What bothers me a lot is that many one here are easy about of moving to much more complicated technology, before knowing where exactly current technology fails to deliver and if it is actually easy fixable.

[Probeman]

The shortcomings in software/firmware of current technology is often overlooked, the lack of possibility to discuss the hardware (no schematics, or schematics provided to end-user with strict NDA clause) freely is one of main obstacles. I.e. there is this new thread about dead times of WDS. I could not convince anyone there why dead time is calculated wrong at widely used diff mode, and I am still not sure probeman had understood me correctly in numerous exchange of replays in PM. Contrary to that, I could easily convince there is error in diff mode dead time calculations the Cameca Software engineers by pinpointing/describing to exact place in schematics with a single e-mail, and that is going to be fixed in next Peaksight release (5.6).

In case anyone is wondering what sem-geologist is talking about here is the equation he suggests for differential mode:

This is a simple modification to the normal dead time expression and obviously if one is in integral mode the two counts rates will be equal and there is no net effect. We are currently evaluating how much of an effect we observe in the dead time correction when in differential mode and utilizing this new expression.

Perhaps sem-geologist can provide some real world data examples of using this new dead time expression?

[Nicholas Ritchie]

P.S. I nearly finished gathering factual pieces, and soon am going to open new thread in this forum showing currently used counting technologies and solutions by Bruker and Cameca WDS (measured stuff), AMPTEK, CREMAT published and available hardware.

You might look at pnSensor (https://www.pnsensor.de/Welcome/index.php) - they have a lot of innovative X-ray detector designs.

[sem-geologist]

Perhaps sem-geologist can provide some real world data examples of using this new dead time expression?

I wish I would have something to show, but currently I am still in exploratory mode too. I use Peaksight 6.5 which still has no ability to use that. The greatest difference is when using narrow PHA window and PHA is really filtering something. There is basically three cases: 1) moderate-to-high count rate where narrow PHA window is used to pass only single pulse and filtering out double and triple (or more) pulse pile-ups. 2) using narrow PHA to filter out higher order peaks interfering with background or measured peak (it can affect trace measurements). 3) using narrow PHA to cope with pulse pile-up and higher orders simultaneously.
When using wide PHA window and there is no higher order interferences also low to moderate-low count rates (up to 25 kcps) - the effect (difference) will be minimal or hardly observable.

Yeah I know there is this problem with PHA shifts with increasing counting rate. I had identified the exact cause of that problem (Again I need to open that thread with review about detectors and counting pipelines), and thought up some not straight forward or counter-intuitive solution, which works more-less up to 80 kcps (in some cases maybe even up to 100 kcps) for high pressure detectors. Combined with rightly used dead time formula at last we could do something with this haunting pulse pile-up's to some degree and have a near linear response of count rate increase to increase of beam current (which now is nonlinear and the non linearity severely increases going above 10 kcps). The proposed dead time equation is logic after seeing how electronics is implemented, and secrecy with schematics (or no schematics) is my main grin with that.

This is not TV, fridge or printer (or other consumer grade goods) - this is the scientific instrument and we should have the right to treat it not as black or magic box. We need 100% of reliance and way to know that what we observe is not just mere analytical artifacts. We need a way to identify exactly where these artifacts originate so that we could eliminate the cause or define a clear pattern how to avoid them. Else we start to develop some kind of cargo cults, which sometimes accidentally works, but in some cases does not (or we are not aware it does not work, which is even worse).

[John Donovan]

This is not TV, fridge or printer (or other consumer grade goods) - this is the scientific instrument and we should have the right to treat it not as black or magic box. We need 100% of reliance and way to know that what we observe is not just mere analytical artifacts. We need a way to identify exactly where these artifacts originate so that we could eliminate the cause or define a clear pattern how to avoid them. Else we start to develop some kind of cargo cults, which sometimes accidentally works, but in some cases does not (or we are not aware it does not work, which is even worse).

Exactly. I could not agree more with you here.

My own efforts with all the EPMA vendors over many decades has been to "expose" the instrument interfaces, so we as a community can understand the functionality of the instrument, in order to improve it.

My own phrase from years ago was : "We cannot do science on a black box!"

[jon_wade]

There has been zero incentive for innovation in the electron probe market for decades now.  With Cameca gone, there is even less.   Yet, any one of us could come up with ten ways to improve the microprobe without even trying.

how do I upvote a comment?

right, surprised the SX line lasted this long.  It was sadly not ready for sale at launch but as of the last field upgrade (late last year) is actually a stable instrument.  QC was lacking from the off though and the lack of development on *all* EPMA instruments is, frankly, telling of the market.  No, EDS isn't good enough for all eventualities, and yes, its use is as much a reflection of ease of use and lack of end-user education.  Are WDS probes increasingly a dead duck?  yes, I think so, but this reflects cost of ownership, lack of development and certain research markets also fading away.

(I suspect the shielded probe is only staying 'live' because theres an onerous exit clause in a Government contract or two)