MeV-Energy X Rays from Inverse Compton Scattering with Laser-Wakefield Accelerated Electrons

We report the generation of MeV x rays using an undulator and accelerator that are both driven by the same 100-terawatt laser system. The laser pulse driving the accelerator and the scattering laser pulse are independently optimized to generate a high energy electron beam (\u3e200  MeV) and maximize the output x-ray brightness. The total x-ray photon number was measured to be ∼1×107, the source size was 5  μm, and the beam divergence angle was ∼10  mrad. The x-ray photon energy, peaked at 1 MeV (reaching up to 4 MeV), exceeds the thresholds of fundamental nuclear processes (e.g., pair production and photodisintegration)

Teaching Domestic Violence in the New Millennium: Intersectionality as a Framework for Social Change

This article describes an intersectional approach to teaching about domestic violence (DV), which aims to empower students as critical thinkers and agents of change by merging theory, service learning, self-reflection, and activism. Three intersectional strategies and techniques for teaching about DV are discussed: promoting difference-consciousness, complicating gender-only power frameworks, and organizing for change. The author argues that to empower future generations to end violence, educators should put intersectionality into action through their use of scholarship, teaching methods, and pedagogical authority. Finally, the benefits and challenges of intersectional pedagogy for social justice education are considered

Local diversity in settlement, demography and subsistence across the southern Indian Neolithic-Iron Age transition: site growth and abandonment at Sanganakallu-Kupgal

The Southern Indian Neolithic-Iron Age transition demonstrates considerable regional variability in settlement location, density, and size. While researchers have shown that the region around the Tungabhadra and Krishna River basins displays significant subsistence and demographic continuity, and intensification, from the Neolithic into the Iron Age ca. 1200 cal. BC, archaeological and chronometric records in the Sanganakallu region point to hilltop village expansion during the Late Neolithic and ‘Megalithic’ transition period (ca. 1400–1200 cal. BC) prior to apparent abandonment ca. 1200 cal. BC, with little evidence for the introduction of iron technology into the region. We suggest that the difference in these settlement histories is a result of differential access to stable water resources during a period of weakening and fluctuating monsoon across a generally arid landscape. Here, we describe well-dated, integrated chronological, archaeobotanical, archaeozoological and archaeological survey datasets from the Sanganakallu-Kupgal site complex that together demonstrate an intensification of settlement, subsistence and craft production on local hilltops prior to almost complete abandonment ca. 1200 cal. BC. Although the southern Deccan region as a whole may have witnessed demographic increase, as well as subsistence and cultural continuity, at this time, this broader pattern of continuity and resilience is punctuated by local examples of abandonment and mobility driven by an increasing practical and political concern with water

Effect of chirp on self-modulation and laser wakefield electron acceleration in the regime of quasimonoenergetic electron beam generation

Strongly self-modulated regime of laser wakefield electron acceleration has been experimentally studied using positively/negatively chirped Ti:sapphire laser pulses with duration ≥45  fs, and intensity ≤1.2×10^{18}  W/cm^{2} interacting with a plasma having density >5×10^{19}  cm^{-3}. The total charge of the high energy electrons produced from self-injection and acceleration in the wakefield was found to depend strongly and asymmetrically on the magnitude and sign of the chirp, which was also corroborated by the forward Raman scattering signals. Generation of low divergence (≤10  mrad), quasimonoenergetic electron beam was observed with a maximum energy of ∼28  MeV for a positively chirped laser pulse of duration ∼70  fs. The observations are explained considering faster rise time associated with a positive chirped laser pulse which generates intense seed for stronger modulation of the laser pulse and consequently stronger wakefield excitation leading to higher electron beam charge and energy

High-quality stable electron beams from laser wakefield acceleration in high density plasma

High-quality, stable electron beams are produced from self-injected laser wakefield acceleration using the interaction of moderate 3 TW, 45 fs duration Ti:sapphire laser pulses with high density (>5×10^{19}   cm^{−3}) helium gas jet plasma. The electron beam has virtually background-free quasimonoenergetic distribution with energy 35.6_{−2.5}^{+3.9}  MeV, charge 3.8_{−1.2}^{+2.8}  pC, divergence and pointing variation ∼10  mrad. The stable and high quality of the electron beam opens an easy way for applications of the laser wakefield accelerator in the future, particularly due to the widespread availability of sub-10 TW class lasers with a number of laser plasma laboratories around the world

MeV-Energy X Rays from Inverse Compton Scattering with Laser-Wakefield Accelerated Electrons

We report the generation of MeV x rays using an undulator and accelerator that are both driven by the same 100-terawatt laser system. The laser pulse driving the accelerator and the scattering laser pulse are independently optimized to generate a high energy electron beam (\u3e200  MeV) and maximize the output x-ray brightness. The total x-ray photon number was measured to be ∼1×107, the source size was 5  μm, and the beam divergence angle was ∼10  mrad. The x-ray photon energy, peaked at 1 MeV (reaching up to 4 MeV), exceeds the thresholds of fundamental nuclear processes (e.g., pair production and photodisintegration)