1. Stability Requirements for Superconducting Wiggler Beamlines
Zhong Zhong

2. NSLSII SCW Design Magnet Peak Field B0 : 6 T 3.5 T
Period Length λ: cm 6 cm
Number of Main Poles (N) :
number of end poles
Wiggler Length (L): m m
Critical Energy EC (0.665BE2): 36 keV 21 keV
Deflection Parameter ( K=0.93B0λ ):
Radiated Power at 500mA (3.9B02LI ): kW 21 kW
Fan size (2K/): milli-radians 6.7 milli-radians
Ampli. e- oscillation (X0= λw K/(γπ)) mm mm
horiz. beam chamber aperture (mm) ? ?
vert. beam chamber aperture (mm)
magnetic (iron) gap (mm)
Table I: specifications of the 6 T wiggler and the alternative 3.5 T wiggler
Facility Manufacturer Field(T) Period (cm) # full-field poles
NSLS X17 Oxford
BESSY II Novosibirsk
CLS Novosibirsk
ELETTRA Novosibirsk
MAX lab ?
Table  II. A partial list of working super-conducting wigglers similar in specifications

3. NSLSII SCW Performance
Flux of the NSLS-II superconducting wiggler, compared with that of NSLS-II bending magnets, damping wigglers, and an alternative superconducting wiggler (W60 in NSLS-II CD0 proposal) with 3.5 T peak field.

4. Sagittal focusing tunable Laue monochromator
NSLSII SCW Beamlines
Beamline Optics & Instrumentation:
2 fixed-wavelength side stations and
2 center stations, white beam or focused monochromatic beam, or both
6-circle Huber diffractometer with bent Laue analyzer for high-resolution diffraction experiments.
Center Hutches
Side Hutches
2-D focusing sagittally bent Laue monochromator
Sagittal focusing tunable Laue monochromator
Vertical focusing mirror

5. NSLSII SCW Experimental Programs
Angular dispersive x-ray diffraction (ADXD)
Large volume press
Diamond Anvil cell
Diffuse scattering
Powder diffraction
Energy-dispersive x-ray diffraction (EDXD)
Strain mapping
Imaging and radiation therapy research
Diffraction Enhanced Imaging
Microbeam Radiation Therapy

6. ADXD, large samples
First crytal
Second Crystal
large volume press, diffuse scattering, powder diffraction, sample size ~ 1 mm.
x-rays are focused by a sagittal focusing Laue monochromator at a magnification of approximately unity.
A position stability of 10% of sample size results in a source-position stability of approximately 100 µm horizontally and vertically.
Vertical angular stability: 10 µrad
A wavelength stability of 10-4
Si 111 monochromator at a Bragg angle of approximately 0.1 rad
Sagittal bending enables
sagittal-focusing
Anticlastic bending
Allows meridional focusing
Lattice strain increases
integrated reflectivity by
1-2 orders of magnitude
compared to perfect crystal

7. EDXD
Strain mapping, deformation experiments, diamond anvil cell, large volume press
Most challenging for orbit stability: use the peak position as a figure-of-merit.
Angle of the incident beam is defined by a fixed slit and the source
Diffraction angle (2) typically being 0.1 rad.
To obtain 10 micro-strains (10-5 d/d) accuracy, the incident angle as defined by the slit and source should be maintained to within 10-6 rad.
The source and beam-defining slit being 50 meters apart, the vertical source position should have a stability of 5010-6 meters, or 50 µm.

8. ADXD, small samples Diamond anvil cell, sample size: a few microns
Source position stability of 100 µm horizontally and vertically.
K-B mirrors (at a magnification of approximately 100:1) are used to focus the x-rays.
A position stability of 1 µm at the sample
Vertical angular stability: 10 µrad
A wavelength stability of 10-4
Si 111 monochromator at a Bragg angle of approximately 0.1 rad

9. Imaging and radiation therapy
DEI and micro-CT, micro-beam radiation therapy (MRT)
The distance between the subject and detector is typically 1 meter, and a resolution of ~1 µm is typically desirable.
50 meters source-to-subject distance,
The source position should be stable to within 50 µm horizontally and vertically.
Synchrotron Beam
Double Crystal Monochromator
Object
Detector
Analyzer
Synchrotron DEI Setup
Synchrotron Radiography

10. Summary: superconducting wiggler
The source position should be stable within 50 µm horizontally and vertically
Source vertical angle should be stable within about 10 µrad.
There is no requirement on source horizontal angle due to the large horizontal divergence afforded by a superconducting wiggler.