Minutes of the Project coordinators meeting on November 29th, 2019 (DRAFT 1)

1. Part A. 

[Agenda item #1] Presentation by Dr. Ulli Eichmann (Project 2.2)

Dr. Eichmann presented the results of several recent experiments in Project
2.2. The first experimental campaign was on the hydrogen molecule at FERMI, 
exploring 2-electron excitation processes with 33 eV photons. The experiment
used multi-colour fields (omega+2-omega XUV + IR), allowing the left-right
asymmetry to be explored.

Dr. Eichmann then presented an investigation of the 1s2p (1s2s) excitation at
the lithium centre in a LiF crystal, at approximately 60 eV photon energy.
Using 4-way mixing techniques allowed the surface and bulk contributions to be
separated.

Finally, double ionization of metastable He and Ne atom was investigated, using
EuroXFEL SQS beamline. Atomic recoil in stimulated-Raman X-ray scattering was
investigated, at 1 keV photon energy and 1 PW/cm^2 intensity. Raman processes
lead to very little recoil. In contrast, spontaneous emission leads to a
significant recoil, allowing the two processes to be separated.

After the talk, a lively discussion followed.

Dr. Woerner asked whether it is possible to shape the XFEL pulses?

Dr. Eichmann replied that the present experiments did not use shaped pulses.
However, the pulses are stable, the shape control is being currently worked on.

Dr. Nibbering asked what is the spot size in the XFEL experiment?

Dr. Eichmann replied that the spot size is 1-2 micrometer, with the peak intensity
of 10 PW/cm2.

Dr. Nibbering asked whether any non-perturbative processes are present at these
field parameters.

Dr. Eichmann replied that none have been seen so far.

Dr. Nibbering asked whether any multi-photon processes can be seen?

Dr. Eichmann replied that generally multi-photon processes for these field
parameters involve sequential absorption of single photons, with two-photon
processes seen near resonances.

1. Part B. 

[Agenda item #2] Minutes approval.

The minutes are approved with no changes or corrections.

[Agenda item #3] Other items.

It was announced that the next MBI Day will be on January 23rd, 2020.

It was further suggested that the next meeting be held in the first half of
January 2020, before the MBI day.

Dr. Kornilov asked whether there will be an institute-wide Christmas party.

Prof. Eisebitt replied that nothing is officially planned. However, there is
still time, provided that somebody volunteers to do the work.

Dr. Kornilov commented that there will be a divisional party in the division A.

The meeting adjourned.
 
Minutes prepared by S. Patchkovskii on January 12, 2020.