Open AccessHigh‐Throughput Asymmetric Double‐Crystal Monochromator of the SAXS Beamline at ELETTRA
Author(s) -
Bernstorff S.,
Amenitsch H.,
Laggner P.
Publication year - 1998
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049597019110
Subject(s) - wiggler , monochromator , beamline , optics , storage ring , physics , crystal (programming language) , photon , scattering , materials science , nuclear physics , wavelength , beam (structure) , cathode ray , computer science , programming language , electron
A new high‐flux wiggler beamline for fast time‐resolved small‐angle X‐ray scattering (SAXS) based on double‐focusing optics has recently commenced operation at the 2 GeV third‐generation storage ring ELETTRA at Trieste, Italy. Its non‐dispersive double‐crystal monochromator contains three pairs of interchangeable asymmetrically cut flat Si(111)‐crystal pairs, each of which is optimized for high throughput at one of the three fixed energies 5.4, 8 and 16 keV. To cope with the severe thermal power load produced by a 57‐pole wiggler on the first crystal of each pair (up to 5.4 W mm −2 and 700 W under normal incidence, for 400 mA), grazing angles of 2° and optimized back‐cooling have been chosen. This solution allows simultaneously a gain of 2.5–3.0 in throughput and, accordingly, in flux density. Finite‐element analysis as well as commissioning tests showed that the cooling layout functions very satisfactorily, and that up to 5 × 10 12 photons s −1 are available at the sample (at 8 keV and 250 mA), as predicted.