A magnetic spectrometer has been developed for the AWAKE experiment at CERN in order to measure the energy distribution of bunches of electrons accelerated in wakefields generated by proton bunches ...in plasma. AWAKE is a proof-of-principle experiment for proton-driven plasma wakefield acceleration, using proton bunches from the SPS. Electron bunches are accelerated to O(1GeV) in a rubidium plasma cell and then separated from the proton bunches via a dipole magnet. The dipole magnet also induces an energy-dependent spatial horizontal spread on the electron bunch which then impacts on a scintillator screen. The scintillation photons emitted are transported via three highly-reflective mirrors to an intensified CCD camera, housed in a dark room, which passes the images to the CERN controls system for storage and further analysis. Given the known magnetic field and determination of the efficiencies of the system, the spatial spread of the scintillation photons can be converted to an electron energy distribution. A lamp attached on a rail in front of the scintillator is used to calibrate the optical system, with calibration of the scintillator screen’s response to electrons carried out at the CLEAR facility at CERN. In this article, the design of the AWAKE spectrometer is presented, along with the calibrations carried out and expected performance such that the energy distribution of accelerated electrons can be measured.
A pulsed vacuum acidification treatment (PVA) applied to zucchini slices and the related response of vegetable tissues, were studied. Results showed that in comparison with a traditional ...acidifying–dipping at atmospheric pressure, PVA may improve the pH reduction as a consequence of the increase of acid solution-vegetable tissues contact area. Nevertheless, the low porosity fraction of fresh zucchini, the variability of the vegetable tissue structure and its mechanical properties did not allow to increase the acidification rate by increasing the vacuum level of 200 mbar. In particular, the study of structural changes showed that the liquid volume changes occurred without significant total volume variation due to the rigidity of vegetable tissues. Probably, this aspect reduced the deformation–relaxation phenomena which have great effect on liquid impregnation at both 200 mbar and 400 mbar. In addition, due to the low viscosity of acid solution it was hypothesize a great filling also at 400 mbar reducing the effect of the increase of vacuum pressure.
The gravitational wave detector VIRGO aims at extending the detection band down to a few Hertz by isolating the mirrors of the interferometer from seismic noise. This result is achieved by hanging ...each mirror through an elastic suspension (Superattenuator), designed to filter mechanical vibrations in all the degrees of freedom. An experimental upper limit of the mirror residual seismic noise at a few Hertz is provided in this paper. This is lower than the thermal noise floor, expected to limit the antenna sensitivity in the low frequency range.
An electron beam derived from stripping of ultrarelativistic lead ions has been used to perform calibration measurements on the electron spectrometer of the Advanced Wakefield experiment at CERN. As ...part of this study, new measurements of the stripping cross-section for ultrarelativistic hydrogen-like lead ions passing through aluminium and silicon have been obtained which demonstrate good agreement with existing measurements and theory. Improvements in terms of electron beam quality and ion beam diagnostic capability, as well as further applications of such an electron beam, are discussed.
Virgo upgrade investigations Amico, P; Alshourbagy, M; Avino, S ...
Journal of physics. Conference series,
03/2006, Letnik:
32, Številka:
1
Journal Article
Recenzirano
Odprti dostop
While the current interferometric gravitational wave detectors are approching their nominal sensitivity, the new generation of detectors is in an advanced design phase. The Virgo collaboration is ...de.ning now the path to arrive to a complete design of the advanced version of the detector within about two years. The upgrades needed to obtain a detector with improved sensitivity in a relatively short time are here discussed.
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