Joint Seminar in Nuclear Physics
Zoom:
PROGRAM:
13:30 - 13:45 - Refreshments
13:45 - 14:05 - Igal Talmi: Milestones and Lessons, Ami Leviatan, Hebrew University Jerusalem (Introduction dedicated to the 100 birthday of Professor Igal Talmi)
14:05 - 15:05 - Intense laser interaction with micro‑bars, Michal Elkind, TAU
Abstract:
The interaction of an intense laser pulse with matter results in the emission of high-energy radiation in the form of MeV electrons and ions, and hard x-rays. Many experiments showed that when the target surface is rough on the scale of the laser wavelength, the coupling of laser energy to high-energy particles increases. To understand this phenomenon I irradiated isolated wavelength scale targets in the form of micrometric Au bars. My results showed two forward-directed electron jets with a small opening angle, having a narrow energy spectrum in the MeV range, and a positive correlation between angle and energy, as well as proton beams with energies exceeding 6 MeV. The latter result exceeds the proton energies emitted from flat foils when irradiated at the same conditions by a factor of three.
Simulations show that following ionization electrons near the target’s edge stay in phase with the laser pulse, allowing the Lorentz force to guide them around the target’s edge. These electrons form attosecond duration bunches while interacting with the laser field over long distances in vacuum and accelerating to within a narrow momentum range. The simulations also revealed that energy transfer from diffracted laser fields to the electrons on both sides of the target, combined with the reduced surface area of the structure, results in a thicker electron sheath and higher ion acceleration gradients.
Beyond the understanding of this basic aspect of how intense light interacts with matter, I will discuss how this new methodology can lead to the possibility of laser-ion acceleration in a cascaded manner from multiple irradiated targets, allowing manipulation of the ion spectrum by optical means.
15:05 - 15:30 - Coffee break
15:30 - 16:30 - MAXIMA-I a Coincidence System for Nuclear Decay Investigations, Sagi Nissim, Soreq Nuclear Research Center, Israel Atomic Energy Commission
Abstract:
MAXIMA-I is a ground-level coincidence system developed at the Soreq Nuclear Research Center; it is designed for low-level activity measurements and nuclear decay investigations. The system combines a high-purity germanium (HPGe) detector and a liquid scintillator detector, enabling simultaneous detection of alpha, beta, and gamma emissions while providing high energy-resolution and near 100% efficiency for detecting alpha and beta detection. Data is recorded in list mode. In addition, the system enables a significant background reduction by selective events, achieving levels comparable to some underground facilities and allowing to investigate faint emissions from certain radionuclides.
Our presentation will cover the system's characterization and showcase its application in studying nuclear decays of 210Po, 99Mo, and 36Cl.
