1. Possible spectrometers
Bent Bragg (after P. Siddons-NSLS)
Mosaic crystal
Bent Laue
Zhong Zhong-NSLS
X-ray Grating
P. Heimann-ALS, S. Hulbert-NSLS

2. Bent Bragg Spectrometer
Strip detector
(200 strips)
76 mm
surface
normal
Si (422)
2 mm
Cu foil
R=3.9 m

3. SPPS Cu near edge - Si (422) dispersive analyzer

4. Cu near edge structure (for reference)

5. Bent Bragg Spectrometer
Strip detector
(200 strips)
76 mm
surface
normal
Si (422)
2 mm
R=3.9 m

6. Adjust crystal asymmetry so that
the Si (422) reflection width is Δθ/200
Corresponding to 200 resolution elements

7. Reflectivity Angle (microradians)
Asymmetric Si (422) FWHM: 100 microrad 8000eV
For reference θB=45;
E=7908 eV
ΔE/E = 1 x 10-4
Reflectivity
100 microrad
Angle (microradians)

8. Und-pinhole distance 200 m Pinhole 2.0 x 0.02 mm2
Photon energy (keV)
On axis
+0.5 mm
+1.0 mm

9. Bent Bragg to do list
Simulation considering position dependent spectrum
Role of jitter
Test K sensitivity with simulated data (including noise)

10. Mosaic crystal spectrometer
180-2θ
2 x Mosaic spread 2ω

11. For PG (002) Δθ=0.3 deg

12. How far away is the detector?
Divide the angular spread into 100 elements,
2Δθ / 100 = 1.0x10-4
For a 2 mm beam
20m

13. Andreas Freund, Anneli Munkholm, Sean Brennan,
SPIE, 2856,68 (1996)
24 keV
10 keV

14. Mosaic crystal to do list
Crystal uniformity ?
Ultimate resolution ?
Experimental geometry (20 m crystal to detector distance)

15. Grating spectrometer
Phil Heimann
RSI, 76, (2005)