Collecting off peak backgrounds using a non conventional method?

[Gseward]

John,

I have never tried this, it seems like it should work, but is there a subtlety waiting to bite me?:

due to spectrometer configuration issues we have the following 3-passes setup for mapping on a 4 spectrometer probe (nominally using MAN background):

Round 1
F,O,Ti,V
Round 2
non,non,Cr,Mn
Round 3
non,non,Fe,Co

So the question is:
If I wanted to use off-peak backgrounds for F and O, could I collect the HI and LO bkgd using a non-conventional method in rounds 2 and 3? e.g. in PI, for round 2, set the PI 'on-peak' position on the unused spectrometer to what is in reality the Hi bkgd position of F (or O); likewise, in round 3 set PI 'on-peak' to Lo bkgd position. Later, in CI, I would define the round 2 F and O maps as the HI bkgd and round 3 F and O as the LO bkgd.

Granted there may have to be some manual file-renaming at some point, but do you think this would work?

[John Donovan]

I have never tried this, it seems like it should work, but is there a subtlety waiting to bite me?:

...

So the question is:
If I wanted to use off-peak backgrounds for F and O, could I collect the HI and LO bkgd using a non-conventional method in rounds 2 and 3? e.g. in PI, for round 2, set the PI 'on-peak' position on the unused spectrometer to what is in reality the Hi bkgd position of F (or O); likewise, in round 3 set PI 'on-peak' to Lo bkgd position. Later, in CI, I would define the round 2 F and O maps as the HI bkgd and round 3 F and O as the LO bkgd.

Granted there may have to be some manual file-renaming at some point, but do you think this would work?

Hi Gareth,
I think this is an excellent idea!   I can't think of any reason it wouldn't work to save quite a bit of time!

I did a file compare between an on-peak and off-peak PrbImg file and the differences (other than the image data, the measured beam currents and time of day) are here:

1,2c1,2
< [ProbeImage]
< ImageFile=zircon majors-traces_00043_SP2_Zr_LPET__MOFF.tif
---
> [ProbeImage]
> ImageFile=zircon majors-traces_00043_SP2_Zr_LPET_.tif
17c17
< Image=12413b4c-271c-4a32-abe6-b5f17e02ace0
---
> Image=e6cb5eb9-d159-4d29-bce3-375cdd352a19
45,46c45,46
< OffsetType=-1
< PixelTime=100
---
> OffsetType=0
> PixelTime=300

So it seems the only thing you'd have to edit (besides renaming the file), is the ImageFile (name) and the OffsetType which goes by this key:

OffsetType = 0    on peak
OffsetType = -1    low (MOFF) off peak
OffsetType = 1    high (POFF) off peak

The only down side I can think of is that the off-peaks maps would have to be acquired for the same time as the on-peak maps, but you're committed to that anyway by running on-peak maps.

Let us know how it works- we want to see pretty x-ray maps!
john

[Philipp Poeml]

It does work, I have done this in the past. But it indeed involves some manual work later to have CalcImage recognize the maps.

[Probeman]

It does work, I have done this in the past. But it indeed involves some manual work later to have CalcImage recognize the maps.

Hi Philipp,
By "some manual work" you mean editing the parameters below, or is there something else you ran into?
john

So it seems the only thing you'd have to edit (besides renaming the file), is the ImageFile (name) and the OffsetType which goes by this key:

OffsetType = 0    on peak
OffsetType = -1    low (MOFF) off peak
OffsetType = 1    high (POFF) off peak