Author Topic: Slit Sizes for JEOL Counters - RePost  (Read 2656 times)

Owen Neill

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    • Electron Microbeam Analysis Laboratory, University of Michigan
Slit Sizes for JEOL Counters - RePost
« on: March 17, 2017, 12:30:18 PM »
Dear fellow JEOL users,

I was wondering what folks typically use for detector slits for their different spectrometer types. My preference so far has been:

- Regular two-crystal: 300um/"up" position.
- Four-crystal: Open/"middle" position.
- H-type: Open/"middle" or 500um/"up", usually 500um.

I'd be interested to hear what other folks prefer. Apologies if this thread is a duplicate, I got an error when I posted it the first time.

Thanks,
OKN
« Last Edit: March 19, 2017, 02:20:29 PM by Owen Neill »

orlandin

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Re: Slit Sizes for JEOL Counters - RePost
« Reply #1 on: February 13, 2020, 11:37:39 AM »
Since this question came up recently between my JEOL engineer and myself, we took some time to collect a little data for comparison and this seemed like a good place to leave it for posterity. It isn't complete because spectrometer 2 currently has a squirrely counter, and I'm not sure that the FWHM is really a good metric for 'peak width' since it scales with cps. Also not sure I trust the Si reading on spc 3 at 300 microns - it might have been between slits since they are a little sticky and the drop in cps seems too dramatic.

I guess it seems to me that 500 micron slits on the PET/LIF (H or not) xenon counters (3, 4, and 5) are best for most applications, and that the 3mm slit for TAP/LDE flow counters (1 and 2) is probably what you want if you want to keep light element analysis as an option at <major concentrations. I'd love to hear if anyone has any other thoughts on the subject! I'm slowly getting over my terror of adjusting the slits and am starting to think of them as potentially useful tools.

Karsten Goemann

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Re: Slit Sizes for JEOL Counters - RePost
« Reply #2 on: February 26, 2020, 04:05:28 PM »
We have one 4-crystal and four L-type spectrometers and we use the medium slit for pretty much everything. We don't do much light element / LDE crystal type work other than F Ka on LDE1L, so it's mostly a combination of TAP/PET/LiF(L) crystals.

With the open slit we get higher background and broader peak tails, see e.g. SiKa on TAP and to some extent also for CaKa on PETL in graphs below. Better spectral resolution with 300 um slit for those lines without sacrificing much peak intensity. Not much difference really for FeKa on LiFL.