RTs: Arnold, Enders, Galatyuk, Isaak, Matei, Tanaka, Ticos, Ur, Ursescu

Project Area Overview: This research area is devoted to the development of methods and instrumentation for work areas A and B, capable of producing, coping with, and exploiting the extreme peak intensities of novel particle and laser beams. It will comprise the development of dedicated instrumentation for the special needs of research in the fields of Nuclear Photonics including scientific contributions to the completion of the VEGA system.

Laser-induced particle acceleration may be further enhanced by optimizing the laser-target interaction. The training projects will address the most promissing research topics either by optimizing the laser pulse delivered onto the target or by utilizing solid targets with particular features. Subsequent characterization, capture, and transport of laser-generated charged-particle beams require the development of particular transport ion-optics and of radiation-hard particle detectors with high spatial segmentation and best possible time resolution (so-called 4-D detectors). 4-D particle detectors with a time resolution of better than 50 ps and improved radiation hardness based on diamond detectors or on the Low-Gain Avalanche-Diode (LGAD) technology, will be developed and applied for instance for the characterization of laser-generated radiation from work area A.

In order to study dipole strengths around the particle threshold and gamma/neutron-decay branches, the simultaneous detection of γ-rays and neutrons is necessary. Existing detector arrays need to be newly arranged and combined to make use of the specific angular distributions of gamma-rays and neutrons emitted from the nucleus after excitation by a fully-polarized beam. Also, further developments of the detector signal readouts are necessary.

Tools and methods for improving the performance and control of ELI-NP’s VEGA system are addressed including developments on VEGA electron-beam diagnostic elements applying methods from artificial intelligence for improved beam tuning and stabilization, developments of novel gamma-beam diagnostics and monitoring capabilities, and studies on optimizing the lattice of VEGA’s storage ring for increased intensity of gamma-beam production.

While VEGA will be a third-generation gamma-ray source based on the process of Laser-Compton backscattering (LCB) on an ultra-relativistic (γ > 103) electron beam in a storage ring, its intensity and brilliance are subject to the inevitable emittance limitations inherent to a storage-ring design. For overcoming this limitation towards brilliances even beyond what will be available soon at the VEGA system of ELI-NP, we will develop the design of brilliant MeV-ranged photon sources using different a further advanced approach. We will investigate the design of a fourth-generation gamma-ray source based on the process of LCB on an electron beam from a linear accelerator (linac) with superior emit-tance as compared to a storage ring. The lattice of an ultimate fourth-generation photon sources based on LCB on the beam of a high-power energy-recovery linac will be established. As the emittance of an electron linac is ultimately limited by its electron gun, research on laser-cathode photo-guns aim at lowest possible emittance.

MeV-ranged photon beams from fourth-generation photon sources will make new methodological approaches possible. Photonuclear cross sections are usually determined relative to well-known calibration standards. To date, the precision of those standards is limited for instance due to imprecise knowledge of the effective temperature of the investigated chemical compound. Therefore, a new method based on temperature-dependent self-absorption experiments will be further advanced to enable measurements of natural nuclear level widths providing improved data for commonly used calibration standards with unprecedented precision.