BM29 - Some History

José Goulon, as the ESRF EXAFS group leader, and Nickolas B. Brookes, as the first beamline scientist during the construction phase, developed the BM29 project and were very strongly involved during the construction phase and until N.B. Brookes moved over to the installation of ID12b.
In the initial project, the BM29 operation was divided into two parts. In phase one, a dynamical sagittal focusing via a bent second monochromator crystal was planned, in combination with a harmonic rejection using a 4 multilayer mirror device, and in phase two, a vertically collimating mirror system was envisaged downstream of the monochromator. Today, the beamline is operating without mirrors and using detuning to suppress the influence of higher harmonics. A brand new double mirror system will be commissioned in the last few months of 2004.

The infrastructure such as optics and experimental hutch and control cabin were installed by June 1994, and installation of the beamline components started in July of that year. Paul Loeffen and Stefan Müllender were in charge of the whole beamline installation and performed the beamline commissioning that started in October 1994. At that time, the technicians were shared within the whole EXAFS group and Jacob Jensen was mainly involved during the commissioning phase. The strong input of Louis Leclerc and Serge Feite in setting up the monochromator and multilayer device has also to be acknowledged. From May 1996 on, Jacob Jensen (electronics) and Sebastian Pasternak (mechanics) were officially attached to the beamline, and shared with ID24.

Beamline operation started in the second half of 1995, and shortly afterwards Adriano Filipponi arrived as first scientist. During this first operation period, control problems of the 4 mirror device resulted in the decision of the beamline responsible not to pursue further development of this device. Until the end of 1996, the heart of BM29's acquisition macros and scanning modes were developed mainly by the scientific staff (A. Filipponi et al.). BM29 now works in transmission geometry as standard, using a feedback controlled detuning of the first monochromator crystal for harmonic rejection. Fluorescence experiments can be performed using photodiodes or a Ge detector of the ESRF detector pool (single and 13-element detector). EXAFS in reflectivity or total electron yield mode are partly feasible and under further development.

Figure [C.1] summarises the periods and positions of the different persons that were involved in the beamline since its early years (up to end 2004). Not included in this figure are Nickolas B. Brookes, who was responsible for BM29 during the construction phase, and José Goulon, who was strongly involved throughout this time and acting as beamline responsible during the periods without first scientist.

Fig. C.1: BM29 personnel in alphabetical order, from 1994 up to 2005.