Introduction

Beamline ID14 is an undulator beamline on a high ß section dedicated to monochromatic macromolecular crystallography. Using three undulators, it provides high brilliance at around 13.3 keV, as well as wide tunability between 7.0keV and 14.5keV. Based on the Troika concept, this beamline has have four stations: three side stations using thin diamond crystals, and an end station with a double crystal monochromator and a toroidal focusing mirror. These stations are operated independently to allow four different user groups in protein crystallography (protein in solution fro EH3) to collect data simultaneously. Each station has an on-line CCD detector

Layout of ID14 for the four experimantal stations. OH1: first optics hutch for three diamond monochromators and optics for the sidestations ID14-1, ID14-2 and ID14-3. OH2: second optics hutch for the endstation ID14-4; EH1, EH2, EH3 and EH4 experimental hutches; CC1, CC2, CC3 and CC4: control hutches for users; CC0: control hutch for the optics hutch OH1.

Source

The beamline has three undulators, all with a minimum gap of 16 mm and a length of 1.6 m. The first undulator, with a periodicity of 42 mm, is tunable over a wide wavelength range, and will be used to provide the beam for experiments outside the standard energy range of 11.5 to 13.5 keV. The second undulator with a periodicity of 23 mm is a single line undulator providing highest flux for experiments between 11.5 and 13.5 keV. The final undulator is optimised for Se edge experiments, with the peak flux at around 12.7 keV.

Source Characteristics

Three undulators in tandem on a high ß section	U42	U23	U24.4
magnetic period	42 mm	23 mm	24.4 mm
Kmax	2.08	0.42	0.52
source size (rms)	338 x 23 µm

Optics Hutch: OH1

The principal elements along the direct beam are in OH1: prepumping vessel primary slits, attenuator, secondary slits, three diamond monochromators, beamshutter and then in OH2: attenuator, secondary slits, monochromator, toroidal mirror, secondary slits and beamshutter. The elements on the sidebranches are: Ge(220) crystal and multilayer or toroidal mirror and beamshutter.

The X-ray beams for the side stations are provided by transparent diamond monochromators. These monochromators use the (111) reflection in Laue or in Bragg mode from thin (0.05 - 0.15 mm) diamonds inserted into the white beam. A second crystal (for ID14-1: a sagitally focusing Ge (220) crystal and for ID14-2 and ID14-3 a plane Ge (220) crystal), will restore the beam direction parallel to the main beam. A third optical element (for ID14-1: a bent multilayer and for ID14-2 and ID14-3: a toroidal mirror), will focus the beam in the horizontal direction and reject higher harmonics.

Experimental Stations ID14-1 , ID14-2 and ID14-3

These stations are conceived for standard experiments in macromolecular crystallography using a fixed wavelength around 0.93Å (below most interesting absorption edges). The stations are highly automated and equipped with mini-diffractometer (no diffractometer in the case of EH3) and sample changer. Station ID14-2 has a plane Ge(220) crystal as the second element and then a fixed radii toroidal mirror for focusing the X-ray beam. Station ID14-1 retains the sagital focusing Ge(220) crystal of station ID14-3 and horizontal focusing is accomplished using a multilayer element. The experimental hutches of these three stations are deliberately identical for the users. Experimental stations are equipped with ADSC Q4 type detectors, EH3 with Vantec-2000 of Bruker.

Data acquisition and analysis

A software package for beamline control, data acquisition and data analysis is being developed to fulfil the requirements of the beamlines. This package, mxCuBE (BsxCuBE in the case of ID14-3), has ongoing development to build a fully automatic data acquisition and processing tool. More information about mxCuBE can be obtained from Darren Spruce. Some basic goals are:

• Automatic on-line data analysis as the images are collected.
• Interfaces to data processing programs.
• Database archiving of experimental information in order to deal with the high volume of data that is produced by the beamlines and allow local/remote auto-processing.

These goals are being developed in association with the DNA project between ESRF, Mosflm authors and Daresbury as well as the in-house PXWEB project.