Good vibrations: diary of an ESRF expert visiting SESAME

By Marc Lesourd, ESRF.

"This story starts a decade ago when Maher Shehab spent some time at ESRF to share and acquire expertise in the vibration measurement field, where I was the self-proclaimed expert. Today he is the Head of Mechanical Engineering at SESAME. He contacted me last autumn with an invitation to Jordan to perform vibration measurements on SESAME's site.

Some weeks later, we finally had a plan for the measurement campaign, my equipment was in a wooden box already in Amman, my brand new passport was in my pocket, I could read a few Arabic letters and I was ready to go in the seat of a 737 Boeing.

I immediately felt at home at SESAME thanks to the very warm welcome from all the staff. The installation also reminded me of the beginnings of the ESRF, with large open spaces and very few beamlines. The machine girders with magnets looked familiar too, except for the colours. My material was still held at the customs so I had some time to visit the premises thoroughly. At lunch break, I ventured outside in the surrounding hills where olive trees were hardly filtering the blazing, mid-April sun.

Maher and I agreed to perform several distinct measurements, including characterisation of the concrete slabs in the experimental hall, long-term measurement during day and night and at low frequency, measurement on the optical and experimental components of the existing beamlines and assessment of the vibration response of a machine girder and magnets.
With such a packed agenda, we got down to work as soon as my equipment made it on site.

Since the electrons were soon going to flow back in the storage ring after a few weeks’ interruption, I had better finish the girder characterisation. That led me to missing the bus to Amman for the first of many occasions. Fortunately, my new colleagues were helpful and I always made it back to the hotel.

The outcome of my work is that the girder-magnet assembly at SESAME is shown to have a relatively good performance. Coupled with the very low floor vibration levels, the stability of the electron beam should be relatively good.

Girder and magnets in good vibrations

The week-end break was more than welcome with a lot of swimming in the tumultuous wadi-mujib, the lively hotel pool and the Dead Sea.

Then the measurements resumed on the beamlines, namely IR, EXAFS and Materials Science (in commissioning), with the precious help of SESAME scientists Gihan Kamel and Messaoud Hardouche. Finally, I managed to cover two-thirds of the experimental hall slabs and discovered no major flaws. A large amount of time was devoted to passing on expertise and information about the data collection and processing to Shehab.

Needless to say, my collaboration with SESAME on these matters will carry on, and who knows ("inch Allah" as they say locally), I may well be back in Jordan."