Observation of parametric X-rays produced by 400 GeV/c protons in bent crystals

Abstract

Spectral maxima of parametric X-ray radiation (PXR) produced by 400 GeV/c protons in bent silicon crystals aligned with the beam have been observed in an experiment at the H8 external beam of the CERN SPS. The total yield of PXR photons was about 10(-6) per proton. Agreement between calculations and the experimental data shows that the PXR kinematic theory is valid for bent crystals with sufficiently small curvature as used in the experiment. The intensity of PXR emitted from halo protons in a bent crystal used as a primary collimator in a circular accelerator may be considered as a possible tool to control its crystal structure, which is slowly damaged because of irradiation. The intensity distribution of PXR peaks depends on the crystal thickness intersected by the beam, which changes for different orientations of a crystal collimator. This dependence may be used to control crystal collimator alignment by analyzing PXR spectra produced by halo protons

Advanced Channeling Technologies in Plasma and Laser Fields

“…This activity takes place within international CERN project UA9 and aims in LHC beams collimation based on crystal channeling phenomenon. UA9 LNF team has proposed to use parametric X-ray radiation (PXR) for diagnostics of both beam-crystal orientation and crystal quality; first PXR measurements for SPS CERN protons in a bent crystal have been performed and successfully proved the predictions for PXR making evident the peak structure in the radiation both spectral and angular distributions [54][55][56]. A new phenomenon on effective deflection of relativistic hadron and lepton beams by crystal miscut surface has been predicted [57,58].…”

Monte Carlo modeling of crystal channeling at high energies

“…For a crystal used as a collimator in a synchrotron, this effect is strongly reduced as particles interact only with the part of the device close to the beam. Other types of crystals as well as compound crystals were also tested in the scope of the experiment such as thin flat crystals allowing to investigate the PXR 2 [61,62] or multi-strip crystals, consisting of several identical strips oriented so that a particle reflected from a given strip would also undergo volume reflection in the next ones [61,63]. The model described in chapter 3 can in principle be applied for simulating such compound crystals, assuming a proper FLUKA geometry describing the crystal properties.…”

Characteristic X-ray radiation excited by 450 MeV/nucleon C+6 ions and 1.3 GeV protons in extracted and circulated beams of accelerator U70

“…However, the radiation background in the vicinity of the accelerator can be significant at measurements of X-ray spectra, see e.g. [6,7]. In present paper we describe results of our measurements of the CXR spectra excited in different targets by beams of moderate relativistic energy available in runs 2013/ 2014.…”