Beamline 12-BM / BESSRC-CAT

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Scientific focus:

Spectroscopy, x-ray scattering, and diffraction

Scientific programs:

Materials science

x-ray scattering
diffraction
spectroscopy

Geoscience

mineral-liquid interface characterization by x-ray scattering and spectroscopy

Chemistry

EXAFS and XANES spectroscopy of actinides and lanthanides

Atomic Physics

Optics & Optical Performance

BESSRC standard monochromator

2.4-22 keV energy range Si(111) focused
7.5-100 keV energy range Si(333)
35 mm offset
water cooling
UHV vacuum compatibility

Mirrors

(removable double-mirror system)
down deflection, flat figure, Pd coating
up deflection, toroidal figure, Rh coating
22 keV energy cutoff

Experiment Stations

12-BM-A

white beam first optics enclosure
white beam slits
monochromator and mirror system

12-BM-B

monochromatic beam station
x-ray scattering
diffraction
spectroscopy (EXAFS and XANES)

Detectors

ionization chambers
Bicron
Lytle detector
solid-state detectors
single-element Si and Ge
Canberra 9-element Ge

Beamline Controls and Data Acquisition

Linux workstation running EPICS with VME and SPEC software
Windows NT running EPICS applications
Macintosh with MacOS software running EPICS applications

Beamline Support Equipment/Facilities

12-BM-B

spectroscopy table
6-circle Huber goniometer

Bending Magnet Source Characteristics (nominal)

source	APS bending magnet
critical energy	19.51 keV
on-axis peak brilliance at 16.3 keV	2.9 x 10¹⁵ ph/sec/mrad²/mm²/0.1%bw
on-axis peak angular flux at 16.3 keV	9.6 x 10¹³ ph/sec/mrad²/0.1%bw
on-axis peak horizontal angular flux at 5.6 keV	1.6 x 10¹³ ph/sec/mradh/0.1%bw
source size at critical energy
Σ_x	145 μm
Σ_y	36 μm
source divergence at critical energy
Σ_x'	6 mrad
Σ_y'	47 μrad