Laser-plasma accelerator group

Abstract:

In multi-pulse laser wakefield acceleration (MP-LWFA) a plasma wave is driven by a train of low-energy laser pulses separated by the plasma period, an approach which offers a route to driving plasma accelerators with high efficiency and at high pulse repetition rates using emerging technologies such as fibre and thin-disk lasers. Whilst these laser technologies are in development, proof-of-principle tests of MP-LWFA require a pulse train to be generated from a single, high-energy ultrafast pulse. Here we demonstrate the generation of trains of up to 7 pulses with pulse separations in the range 150–170 fs from single 40 fs pulses produced by a Ti:sapphire laser.

Abstract:

In multi-pulse laser wakefield acceleration (MP-LWFA) a plasma wave is driven by a train of low-energy laser pulses separated by the plasma period, an approach which offers a route to driving plasma accelerators with high efficiency and at high pulse repetition rates using emerging technologies such as fibre and thin-disk lasers. Whilst these laser technologies are in development, proof-of-principle tests of MP-LWFA require a pulse train to be generated from a single, high-energy ultrafast pulse. Here we demonstrate the generation of trains of up to 7 pulses with pulse separations in the range 150–170 fs from single 40 fs pulses produced by a Ti:sapphire laser.

Abstract:

Production of exclusive dijets in diffractive deep inelastic e±p scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb-1. The measurement was performed for γ∗–p centre-of-mass energies in the range 9025GeV2. Energy flows around the jet axis are presented. The cross section is presented as a function of β and ϕ, where β=x/xIP, x is the Bjorken variable and xIP is the proton fractional longitudinal momentum loss. The angle ϕ is defined by the γ∗–dijet plane and the γ∗–e± plane in the rest frame of the diffractive final state. The ϕ cross section is measured in bins of β. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.

Abstract:

Phase retrieval problem occurs in a number of areas in physics and is the subject of continuing investigation [1-15]. One dimensional case, for example, an electron bunch temporal profile reconstruction, is particularly challenging. Frequently applied methods, are reliable if the Blaschke phase [10-12] contribution is negligible. This, however, is neither known a priori nor can it be assumed for an arbitrary profile. In this work we present a novel algorithm with additional constraints which gives reproducible, stable solutions for profiles, both artificial and experimental, otherwise unresolved by existing techniques.