Nondestructive Detection of Heavily Shielded Materials by Using Nuclear Resonance Fluorescence with a Laser-Compton Scattering γ-ray Source

Abstract

We perform a proof-of-principle experiment for a nondestructive method for detecting the elemental and isotopic composition of materials concealed by heavy shields such as iron plates with a thickness of several centimeters. This method uses nuclear resonance fluorescence (NRF) triggered by an energy-tunable laser-Compton scattering (LCS) -ray source. One-dimensional mapping of a lead block hidden behind 1.5-cm-thick iron plates is obtained by measuring an NRF -ray of a lead isotope 208 Pb. We observe a 5512-keV -ray from 208 Pb excited by the quasi-monochromatic LCS -rays with energies up to 5.7 MeV. The edge position of the lead block is consistent with the exact position within the uncertainty.

Laser Pulses for Compton Scattering Light Sources

“…In practice, however, a shorter pulse is not available and in many cases not required. Many different implementations of the FROG measurement have been implemented utilizing the 3 rd order (3)  nonlinearity. These include Polarization Gated (PG-FROG), where the nonlinearity is the nonlinear polarization rotation of the probe pulse when mixed with a gate pulse; third harmonic generation (THG-FROG), where the measured signal results from the four-wave mixing process; self-diffraction (SD-FROG) where the signal results when two of the overlapping beams set-up a grating which diffracts portions of both beams along new k-vectors directions.…”

Femtosecond pulse trains of polychromatic inverse Compton γ-rays from designer electron beams produced by laser-plasma acceleration in plasma channels

“…This accordion effect [5] causes periodic self-injection of ambient electrons and their subsequent acceleration without quality degradation, while the negative chirp of the driver reduces the pollution of electron spectra by a low-energy background. The first-principles numerical simulations show that, due to the low phase space volume, clear separation of spectral components in energy, and a minimal amount of noise, the comblike electron beams can drive compact, tunable, multi-color ICS γ-ray sources that can find applications in nuclear photonics and radiography [19][20][21]. Natural mutual synchronization of fs-length electron bunches and γ-ray flashes may be an asset to pump-probe experiments and laboratory modeling of single-event effects.…”

“…These comb-like beams may find a unique application as drivers of all-optical γ-ray sources [6][7][8][9][10][11] based on the inverse Compton scattering (ICS) mechanism [12][13][14]. The production of bright, psduration ICS γ-rays has been earlier demonstrated with head-on collisions of intense laser pulses and electron beams from conventional accelerators [15][16][17][18][19][20][21][22]. These γ-rays, which are well collimated, quasi-monochromatic (QM), and have a high degree of polarization, are attractive as electron beam diagnostics [15].…”

“…These γ-rays, which are well collimated, quasi-monochromatic (QM), and have a high degree of polarization, are attractive as electron beam diagnostics [15]. ICS γ-rays are also employed in the generation of polarized positrons from dense targets [17] and to demonstrate nuclear fluorescence [19][20][21]. Nuclear photonics applications benefit from the portability and unprecedented degree of control over the radiation spectrum afforded by an all-optical γ-ray source.…”

Design of narrow-band Compton scattering sources for nuclear resonance fluorescence

“…In Compton scattering sources, a short laser pulse and a relativistic electron beam collide to yield tunable, monochromatic, polarized gamma-ray photons. Several projects have recently utilized Compton scattering to conduct NRF experiments: Duke University [3], Japan [4], and Lawrence Livermore National Laboratory (LLNL) [5][6][7]. In particular, LLNL's Thomson-radiated extreme x-rays (T-REX) project demonstrated isotope-specific detection of low density materials behind heavier elements [5].…”