Ralf Röhlsberger for the MCLS* collaboration and for the 45Sc collaboration The nuclear resonances of Mössbauer isotopes provide extremely narrow energy references for high-resolution spectroscopy. This qualifies them for applications in condensed matter physics as well as for studies in fundamental physics and extreme metrology. Since the pioneering experiment by E. Gerdau et al. [1] at the storage ring DORIS (DESY, Hamburg), the technique of nuclear resonance scattering has found widespread applications at hard X-ray synchrotron radiation sources worldwide. Its implementation and use at hard X-ray laser sources started with one experiment performed at SACLA in Japan reported so far [2]. In 2022 we could perform the first experiments on nuclear resonance scattering at the European XFEL. One study was conducted at the 14.4 keV resonance of 57Fe aiming at applications in x-ray quantum optics in a collaboration with researchers from Friedrich-Schiller-Universität Jena, the Max Planck Institute of Nuclear Physics in Heidelberg, the University of Freiburg and DESY. The other experiment, initiated by researchers from Argonne National Laboratory and Texas A&M University in College Station, USA, succeeded to achieve the first photonic excitation of the ultranarrow 12.4 keV resonance of 45Sc for future applications in extreme metrology. Employing the 14.4 keV nuclear resonance of 57Fe we aimed at the realization of multiphoton excitation in forward scattering from an ensemble of Mössbauer nuclei. Due to the radiative coupling between the nuclei in the ensemble, an enhanced decay rate (superradiance, SR) and collective energy shifts (collective Lamb shift, CLS) appear as characteristic signatures in the scattered light. So far, SR and CLS have been extensively studied in the single-photon excitation regime at synchrotrons. Here we were aiming to reveal the spectral properties of the nuclear exciton under multiphoton excitation conditions, especially with the goal to determine the CLS as function of the number of photons that resonantly excite the nuclear ensemble. So far, the spectral properties under multiphoton excitation conditions have neither been approached theoretically nor experimentally. Our experiment in 2022 was mainly devoted to reliably detect the nuclear forward scattering signal in the presence of the extremely intense radiation pulses of the European XFEL. To our great surprise, under these conditions a 8 mm thick 57Fe foil appeared to be only 1 mm thick, as illustrated in Fig.1. The microscopic mechanism for this unique behavior is still under investigation. |
|
|
|
Recent publications
Stöhlker,
T.;
Mokler,
P. H.;
Geissel,
H.;
Moshammer,
R.;
Rymuza,
P.;
Bernstein,
E. M.;
Cocke,
C. L.;
Kozhuharov,
C.;
Münzenberg,
G.;
Nickel,
F.;
Scheidenberger,
C.;
Stachura,
Z.;
Ullrich,
J.;
Warczak,
A.
Ground-State Transitions in One-Electron and 2-Electron Bi Projectiles
Physics Letters A,
168
:285
August 1992
Stöhlker,
T.;
Kozhuharov,
C.;
Livingston,
A. E.;
Mokler,
P. H.;
Stachura,
Z.;
Warczak,
A.
Radiative Electron-Capture into the K-Shell, L-Shell and M-Shell of Decelerated, Hydrogenic Ge Projectiles
Zeitschrift Für Physik D - Atoms Molecules and Clusters,
23
:121
June 1992
Stöhlker,
T.;
Geissel,
H.;
Folger,
H.;
Kozhuharov,
C.;
Mokler,
P. H.;
Münzenberg,
G.;
Schardt,
D.;
Schwab,
T.;
Steiner,
M.;
Stelzer,
H.;
Sümmerer,
K.
Equilibrium Charge State Distributions for Relativistic Heavy-Ions
Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms,
61
:408
October 1991
Mokler,
P. H.;
Stöhlker,
T.;
Kozhuharov,
C.;
Stachura,
Z.;
Warczak,
A.
Radiative Electron-Capture - a Tool for Structure Studies of Heavy Few-Electron Ions
Zeitschrift Für Physik D - Atoms Molecules and Clusters,
21
:197
September 1991
Stöhlker,
T.;
Mokler,
P. H.;
Kozhuharov,
C.;
Livingston,
E. A.;
Ullrich,
J.
Capture of Quasi-Free Electrons into Highly Charged, Heavy Projectiles
Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms,
56-7
:86
May 1991
Stöhlker,
T.;
Kozhuharov,
C.;
Livingston,
A. E.;
Mokler,
P. H.;
Ullrich,
J.;
Fricke,
B.
2-Photon Decay of the 1s2s S-1(0) State in Kr-36(34+) Produced by Resonant Transfer and Excitation
Zeitschrift Für Physik D - Atoms Molecules and Clusters,
21
:S233
March 1991
Warczak,
A.;
Stachura,
Z.;
Szymanski,
A.;
Stöhlker,
T.;
Kozhuharov,
C.;
Livingston,
A. E.;
Mokler,
P. H.;
Reusch,
S.
Evidence for Resonant 2-Electron Capture and Excitation in Collisions of H-Like Ge with Ne
Physics Letters A,
146
:122
May 1990
Mokler,
P. H.;
Reusch,
S.;
Stöhlker,
T.
Heavy-Ion Beam Tailoring Using Dielectronic Recombination
Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment,
278
:93
May 1989
Mokler,
P. H.;
Reusch,
S.;
Stöhlker,
T.;
Schuch,
R.;
Schulz,
M.;
Wintermeyer,
G.;
Stachura,
Z.;
Warczak,
A.;
Müller,
A.;
Awaya,
Y.;
Kambara,
T.
Resonant Transfer and Excitation in Swift, Heavy Few-Electron Projectiles
Radiation Effects and Defects in Solids,
110
:39
January 1989
|
|
|
|
