In recognition of a beamline having a limited set of its specifications available in the first user period Diamond introduced a commissioning call in which proposals are peer reviewed, but the emphasis is on which proposals will help with the commissioning process, as well as giving some early results.
For B18 which has been designed as a straightforward spectroscopy beamline it is anticipated that by April 2010 (first user date) all of the Day 1 specifications should be achieved. As the allocation period (Apr – Sep 2010) progresses other capabilities should become available, and so it was felt better if your proposals are subjected to the normal peer review process with some technical constraints.
The User Working Group agreed at the Technical Design Review (Nov 2007) that the Day One specifications are:
| Energy range | 6.5 -19 keV (Mn-Zr, Pm-U) |
| Energy resolution | 2 ∙ 10-4 using Si 111 |
| Energy stability | ±0.1 eV per day |
| Flux@ 8 keV at sample | 5 ∙ 1011 ph/s (Si111) |
| Beam size at sample | 1.0 x 1.0 mm2 (H x V) |
| Beam divergence at sample | 1.92 x 0.22 mrad2 (H x V) |
| Beam position stability at sample | < 20µm per day |
First beam has not yet been obtained on B18 (planned for mid-Nov), so the above is still a best guide to what will be available. However, the beamline construction is progressing well and there is every expectation that the above specifications will be met. In fact it is likely that the beam size at the sample will be smaller. As a guide for users of similar beamlines, the flux does not vary strongly with energy (until E > 20 keV) and depending on setup conditions is roughly x2 more flux than BM29 (ESRF) and x0.5 flux of Super-XAS (SLS). For users familiar with the SRS, despite being a bending magnet, the flux will be approximately 5x that of 7.1 and 9.3 and 1.5x 16.5 for energies <20 keV.
Proposals should be written with the following in mind:
- Both standard transmission and fluorescence using the 9-element Ge SSD will be available. For the first couple of months (April/May) only edges in the range 6.5 -19keV (utilising the Cr stripe part of the beamline and the Si(111) Monochromator) will be possible.
- From the summer (June/July) some simple soft X-ray experiments will be scheduled (2.1 - 4 keV, S-K). Please discuss with the B18 team what detection you require, as we have some options for commissioning drain current, and/or soft X-ray fluorescence detectors.
- By late summer the 2nd platinum stripe part of the beamline will be commissioned, so Cr edge becomes accessible.
- The LN2 sample cryostat holding between 10-20 samples will be available for the whole period and also an RI furnace capable of heating samples to approximately 600°C in an inert atmosphere. For other sample environments please contact the B18 team to discuss whether this would be feasible.
Thus in summary please submit proposals within the table below, but taking in to account all options won’t be available until later in the allocation period.
| Energy range | 2.4 – 19 keV (S–Zr, Ba-U) |
| Energy resolution | 2 ∙ 10-4 using Si 111 |
| Energy stability | ±0.1 eV per day |
| Flux@ 8 keV at sample | 5 ∙ 1011 ph/s (Si111) |
| Beam size at sample | 0.2 x 0.25 mm2 (H x V) |
| Beam divergence at sample | 1.92 x 0.22 mrad2 (H x V) |
| Beam position stability at sample | < 20µm per day |
During this allocation period commissioning will start with the 311 monochromator, but NO high energy proposals will be accepted until the next allocation period. Quick EXAFS and diffraction will also not be available in this period, but will be commissioned in order to come on-line during the next allocation period (Oct 10- Mar 11).