SNO+

Abstract:

To stimulate and support the progress in areas of compact particle accelerators, within research fields including X-ray and THz (T-ray) sources of radiation, non-invasive, electron beam diagnostics that are capable of measuring a single femtosecond electron bunch are required. At the current stage such beam diagnostics for femtosecond-long electron bunches are still not available. The goal of the work presented is to understand the spectral characteristics of coherent Smith-Purcell radiation to enable its quick and reliable interpretation including the longitudinal profile reconstruction of electron bunches. The research presented comprises results from numerical modelling and experimental studies. We use a PiC numerical model to analyse the dependence of radiated spectra dependence on the electron bunch profile, and discuss our results in the context of new experimental data from the E203 experiment at SLAC. Copyright © 2013 by JACoW.

Abstract:

This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4:7 fb–1of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at √s = 7 TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered. Two measurements of αℓP, the product of the leptonic spin-analyzing power and the top quark polarization, are performed assuming that the polarization is introduced by either a CP conserving or a maximally CP violating production process. The measurements obtained, αℓPCPC=–0.035 ± 0.014(stat) ± 0:037(syst) and αℓPCPV= 0.020 ± 0:016(stat)+0.013–0.017(syst), are in good agreement with the standard model prediction of negligible top quark polarization.

Abstract:

We report on recent measurements made at FACET by the E-203 collaboration to test a longitudinal bunch profile monitor based on Coherent Smith-Purcell radiation. The capacity of this monitor to resolve sub-picosecond bunches will be shown as well as a comparison of profile reconstructed for different data sets. We also present recent electromagnetic simulations of the interactions between the beam and the grating as well as the expected resolution of such monitor with a "notch collimator".

Abstract:

The potential of Coherent Smith-Purcell radiation as a longitudinal bunch profile monitor has already been demonstrated and has recently been extended to the sub-picosecond range. As a critical step toward the construction of a single shot bunch profile monitor using Coherent Smith-Purcell radiation it is important to measure very accurately the distribution of such radiation. Optimum background suppression techniques need to be found and relatively cheap detectors suitable for the far infra-red need to be qualified. To perform these tasks a test stand has been installed at the end of the linac of the synchrotron SOLEIL. This test stand and the first results from its commissioning will be presented here.

Abstract:

There is a strong interest in the development of single shot diagnostics of fs relativistic electron bunches within a number of research areas including compact particle accelerators and THz and X-ray sources of radiation. The goal of this work is to investigate some properties of coherent Smith-Purcell radiation and to use it for the reconstruction of the longitudinal profile of a fs-long electron bunch. © 2013 IEEE.