Fast electron beam divergence in foil targets with embedded high-Z gold layers irradiated with ultraintense 527nm laser pulses

We report on experimental measurements of fast electron beam divergence in planar Al targets with buried and surface Au layers, irradiated with second harmonic (2$\omega $, 527-nm) laser light (50 J, 0.7 ps). In particular we study the propagation through the buried high-Z layers, which could deflect the fast electron beams through magnetic fields generated at the layer interfaces. Low prepulse energies, on the order of 10 $\mu $J, enabled electron creation at well-defined surfaces and with cooler energy spectra compared to 1$\omega $; in addition, shots were taken with a controlled 3mJ prepulse to generate a preplasma density profile. K$_{\alpha }$ emission from buried Cu tracer layers was imaged to give electron beam divergence, while electron temperature measurements were made with Bremsstrahlung detectors and electron spectrometers. The results will be presented and compared to PIC and hybrid-PIC simulations.