An old probe service guy here.
Julian and Stewart are correct.
Johan crystals (TAPJ) vs Johansson crystals (TAP)
See the article from Microscopy and Microanalysis

http://www.geoscience.wisc.edu/~johnf/g777/MM/Wittry.pdf



Sent by Mr. "T"

> On Sep 23, 2020, at 1:54 AM, Stuart Kearns <[log in to unmask]> wrote:
> 
> 
> Hi Radoslaw,
> So, I have a document that I’m fairly certain was supplied by JEOL that says:
> Johansson crystals: TAPH, PETHS, LIFHS, PETL
> Johan crystals: TAPJ, PETJ, LIF, LIFL, LIFH, PETH + Multilayers and STE
>  
> That doesn’t answer your question – I had always assumed like Ron, that the ‘J’ simply stood for JEOL. But, they are in any case ‘normal’ crytals – We had TAPJs on our old 8600.
>  
> Best wishes,
> Stuart
> ____________________________
> Stuart Kearns
> School of Earth Sciences
> University of Bristol, UK
> Tel. +44 (0)117 331 5004/5012
> [log in to unmask]
>  
>  
> From: JEOL-Focused Probe Users List <[log in to unmask]> on behalf of Allaz Julien <[log in to unmask]>
> Reply to: JEOL-Focused Probe Users List <[log in to unmask]>
> Date: Wednesday, 23 September 2020 at 09:43
> To: "[log in to unmask]" <[log in to unmask]>
> Subject: Re: [PROBEUSERS] TAPJ, TAPH, TAPL or TAP?
>  
> Hi Radoslaw,
>  
> Unless I am mistaking, historically the “J” indicate that the monochromator geometry is of “Johansson” type (in opposite to Johann). The Johansson geometry has the 2d lattice bent at a radius of 2R, and the monochromator is then further grinded to a R radius, offering thus a perfect focusing of the X-ray on the detector.
>  
> Nowadays it is common to still see it on the PET monochromator (PETJ) but I haven’t seen it on other monochromator… 
>  
> Best,
>  
> Julien
>  
>  
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> 
> On 23 Sep 2020, at 10:10, Michallik Radoslaw (GTK) <[log in to unmask]> wrote:
>  
> Hi,
>  
> I’ve been working on an old JEOL JXA 8600 with the normal “small size” x-tals i.e. TAP. I know that large crystals are i.e. TAPL (normal spectrometer 140mm) and high intensity crystals are TAPH for the H-Type spectrometer with a smaller Rowland circle (100mm).
>  
> But what are i.e. TAPJ x-tals? What does the “J” stands for? I’ve noticed that they are usually mounted with a gas-flow proportional counter.
>  
> I just started recently at my new work place and we’ll have a configuration with TAPJ and PETJ crystals on our new FE-EPMA from JEOL.
>  
> Thank you in advance for your help.
>  
>  
> Kind regards,
>  
>  
>  
> Radoslaw Michallik
> Researcher
> Circular Economy Solutions
> Geological Survey of Finland GTK
>  
> Vuorimiehentie 2K, FI-02151 Espoo, Finland
> Tel. +358 29 503 0345, +358 50 340 9701
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>  
> www.gtk.fi I @GTK.fi​
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