Daniel Haden

Generation of 9 MeV γ-rays by all-laser-driven Compton scattering with second-harmonic laser light.

Gamma-ray photons with energy >9  MeV were produced when second-harmonic-generated laser light (3 eV) inverse-Compton-scattered from a counterpropagating relativistic (~450  MeV) laser-wakefield-accelerated electron beam. Two laser pulses from the same laser system were used: one to accelerate electrons and one to scatter. Since the two pulses play very different roles in the γ-ray generation process, and thus have different requirements, a novel laser system was developed. It separately and independently optimized the optical properties of the two pulses. This approach also mitigated the deleterious effects on beam focusing that generally accompany nonlinear optics at high peak-power levels.

Selective activation with all-laser-driven Thomson γ-rays

A bright, narrow band MeV γ-ray source-ray source based on Thomson scattering using a laser-driven electron accelerator has been developed. We discuss the application of this source for selective activation in regions of high particle (neutron or gamma) production, with minimal absorption in intervening materials.

High-energy radiography of dense material with high flux Inverse-Compton x-ray source (Conference Presentation)

We report the high energy radiography of dense material using MeV all-optical-driven inverse Compton x-ray source. The properties of the inverse-Compton x-ray source are controlled by means of electron energy, electron charge, scattering beam focal spot size and pulse duration to obtain optimized x-ray energy and high flux for dense material radiography. In this experiment, the x-ray has a photon energy of 8 MeV for maximal steel penetration depth, and a flux of 1011 x-ray photons per shot. With this novel x-ray source, we are able to demonstrate radiography of a 10 cm thick “kite” object through a steel shielding with thickness up to 40 cm in a single exposure. The radiography image of the “kite” object though the 40 cm steel has signal to noise ratio of 2 and image contrast of 0.1, and the “kite” object can be clearly distinguished in the image. Combining its tunability, ultrafast pulse duration and micron meter resolution, the all-optical-driven inverse Compton x-ray source provides unique capacities for flash radiography of dense material, and is of interest for ultrafast nuclear physics study.

High-resolution radiography of thick steel objects using an all-laser-driven MeV-energy x-ray source

The recent development of a high-brightness MeV-photon source based on inverse-Compton scattering (ICS) has opened up exciting new possibilities for high-resolution radiography of dense objects. The x-ray beam is extremely bright, micron-source size, with mrad divergence, and high-spectral density, which makes it ideal for studies where high-resolution is required. The x-ray source is tunable over a wide range of parameters and we will discuss how the adjustable source parameters affect both transverse and longitudinal resolution. We then present results on the radiography of a thick steel object using this ICS source, and demonstrate the capabilities of this source with respect to operation at high photon energy while providing high spatial resolution.

Highly Nonlinear Inverse Compton Scattering

X-rays produced by highly nonlinear scattering of electrons by an ultra-intense electromagnetic field (I = 7×10^20 W cm^-2, a_0 ~ 15) are studied experimentally and compared with simulations.

A system to control the energy of a high-power laser system with application to x-ray generation at ultra-high intensity

We demonstrate a system to control the output energy of a high-energy, ultrashort pulse laser system by an order-of-magnitude. This technique is used to control the brightness of an Inverse-Compton x-ray source.

Photonuclear and radiography applications of narrowband, multi-MeV all-optical Thomson x-ray source

The laser-driven Thomson scattering light source generates x-rays by the scattering of a high-energy electron beam off a high-intensity laser pulse. We have demonstrated that this source can generate collimated, narrowband x-ray beams in the energy range 0.1-12 MeV. In this work, we discuss recent results on the application of this source for radiography and photonuclear studies. The unique characteristics of the source make it possible to do this with the lowest possible dose and in a low-noise environment. We will also discuss recent experimental results that study nuclear reactions above the threshold for photodisintegration and photofission. The tunable nature of the source permits activation of specific targets while suppressing the signal from background materials.

A high-energy attenuation system and the application to X-ray generation at ultra-high intensity

We demonstrated an energy attenuation system to control the output energy of a high-energy ultrafast pulse laser system by an order-of-magnitude. This technique was used to control the brightness of an Inverse-Compton x-ray source.