ADC 900 :: APS Octupole

Soft X-ray Scattering Octupole End Station

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The Octupole End Station is used for soft X-ray scattering in magnetic dichroism (XMD) experiments. The system is mainly used for three applications, i.e., constant field for the duration of an x-ray absorption scan, point-by-point field reversal for an XMD photon energy scan, and hysteresis loop measurements.

The ADC Octupole is based on earlier designs and work performed by Elke Arenholz and Soren O. Prestemon at Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, Ca. ADC improved on the ALS design and has performed several design improvement iterations (see chart below)

Eight conical electro magnets (coils) are equidistantly spaced about the surface of a sphere to create an omnidirectional field vector with a magnitude of 1 [T]. The magnets protrude into an ultra high vacuum chamber with a base pressure of 5E-10 [mbar] that houses both the sample and detector apparatus. The entire system is then capable of tilt rotation vertically about the beam axis +/- 45^O. The 1T field is achieved by the combination of fields from 2 or more coils.

Technical Specification Base System:

Peak field magnitude of 1T
Field uniformity of 5% over 10mm cube
Field vector rotatable in any direction
8 magnet coils
Water cooling for 8 coils
Base frame, kinematic, adjustable, 304 SS,
Detector 360^O rotation goniometer
Top sample access
Sample rotation axis
UHV operation @ 5E-10mbar
RGA Analysis
Water flow sensors
Ports for sample, pumping, detector, observation, beamline, vacuum gage, spare

Comparison of ADC and ALS Octupoles

Table 1	ALS Octupole	ADC Gen 1	ADC Gen 2
Peak Field	0.9 T Any direction	1 T Between pole pairs	1 T Any direction
Vacuum Chamber	Sample and Access	Solid Sphere	Split Sphere
Sample Motions	Ø Rotation	Ø Rotation	X,Y,Z,Ø
Detector Motion	Fixed	360^O	360^o
Detector Position Repeat	Fixed	30 arc min Open loop	2.0 arc sec With encoder
Tilt Motion	No	+/- 45^O	+/- 445^O
Load Lock	No	Yes	Yes
Cryo Sample	No	Yes	Yes
Coil Wire Insulation	Single Build	Double Build	Triple Build
Water Cooling	Limited Copper Tubing	Limited Direct Water	Significantly Improved Direct Water

Note: The original idea for this Octupole End Station was originated from ALS:

Elke Arenholz and Soren O. Prestemon
Design and performance of an eight-pole resistive magnet for soft x-ray magnetic dichroism measurements Rev. Sci. Instrum. 76, 083908 (2005)
http://dx.doi.org/10.1063/1.2008027

http://ssg.als.lbl.gov/ssgdirectory/arenholz/Vectormagnet.html

ADC offers a large assortment of synchrotron and neutron equipment including; High Precision Slits, Optical Tables, Lead Shielded Beam Pipes, Micro Ion Chambers, Split Two Axis Ion Chambers, Mirror Systems, Monochromators, Spectrometers, Insertion Devices (EPU, Wiggler, Planar, In-Vacuum, Apple), ID Measurement System and many other Beamline Components. Our products are being used at many synchrotron, neutron, and x-ray facilities around the world including; APS, NSLS, ALS, DLS, NSRRC, BESSY, DESY, CHESS, ESRF, BSRF, CAMD, NSRL, PAL, LNLS, CLS, SSRF, ANKA, KEK, SPring-8, ASP, ELETTRA, MAX-LAB.