Discussion journal of the Mössbauer Community

["Nagy, Denes Lajos" <nagy.denes AT wigner.mta.hu>]

Dear Colleagues,

as you surely know, ESRF has recently been shut down for 18 months for its 
major upgrade Extreme Brilliant Source (EBS). ESRF is organizing a series 
of "EBS Workshops" in 2019 (https://www.esrf.eu/EBSworkshops2019). These 
workshops will cover a multitude of topics, with the aim of gathering 
together users, staff and other experts to discuss and identify strategies 
for performing the best experiments with this new source.

The workshop devoted to the possibilities of nuclear resonant scattering 
(https://www.esrf.eu/nrs-workshop) will be held on 11-12 March in 
Grenoble. Among other speakers, I have been invited to give a talk and to 
contribute to identifying key scientific cases which will benefit most 
from nuclear resonance scattering with the EBS. I would like to ask you to 
come up with your ideas that could be included in my presentation. Indeed, 
I am convinced that the workshop should discuss as much of the ideas of 
the whole international Mössbauer community as possible.

I would be happy to receive your short suggestions preferably until 26 
January (even a few sentences are enough to start with). Alternatively, 
you may wish to reply this call just on the mailing list, hopefully 
initiating a kind of open discussion within the community.

The expected impact of the EBS upgrade to the NRS activity at ESRF will be 
the following (thanks to Sasha Chumakov for this excellent summary):

From the machine side:

- no changes in flux (or, maybe, some + 10%);

- same vertical size of the e-beam (~ 10 μm);

- 20 times smaller horizontal size of e-beam (~ 50 μm).

Due to the nearly the same horizontal divergence, the initial 
(non-focused) beam will be practically the same as before EBS, but 
horizontal focusing will be ~20 times more simple.

From the NRS group side:

- A new, short-focal KB-mirror will be installed. with this mirror, a 200 
nm x 200 nm photon beam size can be reached. Actually, if everything will 
be within specifications, EBS should deliver a photon beam of 100 nm x 100 
nm size.

- In addition, an energy resolution of ~50 μeV will be reached. This 
should be moderately reliable, as 100 μeV is available already now and 
even has been delivered to users.

It is important to note that the nano-size and the μeV resolution cannot 
be provided at the same experiment, i.e. - either - or.

Please remember that the Synchrotron Mössbauer Spectroscopy (SMS) option 
allowing for energy-domain Mössbauer experiments at any bunch mode is now 
available at the NRS beamline.

My personal guess is that the true impact of the EBS upgrade to NRS will 
be the 200 nm x 200 nm (or even smaller) photon beam size rather than the 
50 μeV energy resolution. Frankly speaking, at the moment I don't see 
scientific cases where this latter energy resolution is needed but, 
certainly, I may be wrong.

As concerning the nanobeam, it will open up probably at least two major 
fields.

First, ultra-small samples can be investigated (conceivably, under extreme 
conditions already available at the ESRF NRS beamline).

Second, it will make possible scanning Mössbauer microscopy in the direct 
space with a resolution of 100-200 nm in the direct space, i.e. down to a 
region which, until now, could only be accessed indirectly in the 
reciprocal space by small-angle and off-specular scattering in the 
forward-scattering and grazing-incidence geometry, respectively.

Your input of tangible science cases for these (or other) technical 
approaches (even in a very short, still unelaborated form) will be more 
than welcome. Needless to say, all input will be properly referred to in 
the presentation.

With best regards,

Dénes L. Nagy


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    Denes Lajos Nagy

                      Research professor emeritus

                      Institute for Particle and Nuclear Physics
                      Wigner Research Centre for Physics
                      Hungarian Academy of Sciences
                      H-1525 Budapest, P.O.B. 49, Hungary

                      Telephone: +36 1 392 2517
                      Mobile (office): +36 30 501 8579
                      Mobile (private): +36 20 981 0451
                      Fax: +36 1 392 2598
                      Skype: nagy_denes_lajos
                      E-mail (office): nagy.denes AT wigner.mta.hu
                      E-mail (private): nagydl AT gmail.com
                      Web page: http://www.kfki.hu/~nagy/
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