High efficiency bending of 450 GeV protons using channeling

A novel application of bent crystal channeling to the production of simultaneous particle beams

“…Taking into account the phase-space of the incident beam and the crystal acceptance shown in Figure 3 and simulated by Monte Carlo calculation (see Footnote 4) to Section 3), it represents ~ 0.15 of those protons falling within the the critical angle for channeling with respect to the crystal planes. The transmission found is thus in fair agreement with other measurements [11,12,13] and with theoretical expectation [5,6], taking into account a crystal surface transmission, S ≈ 0.7, and a transmission factor due to dechanneling through the bent crystal of η ≈ 0.2 (see Table II). …”

“…In that case the emittance of the deflected beam is only restricted in the plane of deflection, by the thickness of the crystal and by the critical angle for planar channeling (~ ± 7 µrad for the 110 planes of Si at 450 GeV/c). With a highly parallel beam, transmission efficiencies of ~ 10 -1 for deflections of ~ 10 mrad have been observed [11,12,13].…”

“…3 The choice of crystal material to be Silicon was based on the relative ease of growing a large mono-crystalline ingot, from which a series of similar crystals could be cut parallel to the uniformly-spaced (110) planes. Moreover, we could profit from the experimental data already obtained with similar crystals [11,12]. For the purpose of minimising interactions of protons in the crystal, a material of relatively low atomic weight and density is advantageous.…”

“…The phenomenon of channeling has been discussed extensively in the literature [2,3,4,5] and has recently been reviewed in lecture form [6], giving a complete set of references and a bibliography. Experimental studies, especially on planar channeling and bending, have been performed at various accelerators [7,8,9,10], notably with a beam of 450 GeV/c protons from the CERN SPS incident on a Silicon crystal [11,12,13].…”

Channeling of high-energy particles in bent crystals – Experiments at the CERN SPS

“…The dechanneling fraction was found to be roughly the value predicted by theory [20]. At this point, investigations were made in view of applications for beam de¯ection in the CERN K12 beam for NA48 and for extraction at the LHC and SSC [21].…”