Johann Isaak

Johann Isaak is a leading experimental nuclear physicist serving as Head of Research Data Management and Principal Investigator (PI) of the IRTG 2891 program at the Institute for Nuclear Physics (IKP), TU Darmstadt, Germany. His research focuses on advancing our understanding of nuclear structure through precision photonuclear experiments, particularly in the areas of the Pygmy Dipole Resonance, nuclear resonance fluorescence, and gamma-ray spectroscopy. He actively teaches specialized courses such as "Photonuclear Reactions" and contributes to interdisciplinary nuclear physics education.

Research Interests:

• Experimental Nuclear Physics: Design and implementation of advanced detection systems like DAGOBERT for electron-gamma coincidence spectroscopy.
• Photonuclear Reactions: Investigating nuclear responses to real photons via quasimonoenergetic and polarized beams, focusing on dipole excitations in medium-mass nuclei.
• Pygmy Dipole Resonance (PDR): Pioneering studies on low-lying dipole strength, its systematic behavior across isotopic chains (e.g., Sn, Ce, Te), and implications for nuclear astrophysics.
• Nuclear Structure: Precision measurements of transition strengths, level densities, and gamma-ray strength functions to test theoretical models and the Brink-Axel hypothesis.
• Advanced Detectors and Techniques: Development of high-efficiency spectroscopy setups like y³ at HIγS and AGATA for high-resolution gamma-ray detection.

Publication Trends:

Isaak's recent publications (2020-2025) demonstrate a strong focus on collective nuclear excitations, evidenced by studies on giant dipole resonances, two-phonon states in Sr-88, and quadrupole excitations in tin isotopes. His collaborative work spans international facilities, including HIγS, GRAF, and Legnaro National Laboratories, highlighting his role in large-scale experimental campaigns.

Scientific Contributions:

• Methodological Advances: Introduced model-independent approaches for determining dipole responses via (γ, γ′γ″) reactions, enhancing precision in photon strength function measurements.
• Experimental Leadership: Coordinated multi-institutional projects like the AGATA collaboration and NUMEN project, driving advancements in gamma-ray spectroscopy.
• Educational Outreach: Mentors young researchers through IRTG 2891 and contributes to foundational texts, such as chapters in the Handbook of Nuclear Physics.

Collaborations and Infrastructure: Isaak leverages world-class facilities, including the S-DALINAC accelerator at TU Darmstadt and international gamma-ray sources, to probe nuclear phenomena. His leadership in research data management ensures FAIR principles are integrated into nuclear physics workflows, enhancing reproducibility and data sharing.