Linearly polarized photon beam at MAX-lab

CROSS SECTION ASYMMETRY OF THE 12C(γ,p0)11B AND 12C(γ,p1)11B REACTIONS AT PHOTON ENERGIES 40...55MeV

“…[6] in details. The experimental set up, the coherent bremsstrahlung (CB) beam characteristics, experimental registration apparatus and technique have been described in details in the previous publications [1,3,4,7], thus only brief survey and some new details of the data processing are given here.…”

“…The electron beam with energy E 0 = 192.7 M eV was extracted from the MAX-I storage ring, which worked in a stretcher mode. Then the beam was delivered into experimental area, shown in [1,3,6,7], and was directed onto photon radiators, a diamond crystal of 100µm thick and 50µm Al foil, fixed in a target holder of the goniometer [3]. The beam size on the radiators was no more than 2 mm, and the electron current was ∼ 5...10 nA.…”

“…The beam size on the radiators was no more than 2 mm, and the electron current was ∼ 5...10 nA. The duty cycle of the beam was df ≈ 50% and the divergence, estimated in [3], was no more 0.041 0 (∼ 0.71 mrad). A noninteracting part of the electron beam was deflected to the beam dump by the magnet, where it was absorbed by a Faraday cup.…”

“…The coincidence requirement to overlapping 50% scintillators resulted in 62 channels for detecting the post-bremsstrahlung electrons and total tagged energy range E γ = 21.9...78.8 M eV . The energy resolution smoothly varied from ∆E γ ≈ 0.8 M eV till ∆E γ ≈ 1 M eV [3,7].…”

“…where dσ ∥(⊥) ≡ dσ ∥(⊥) /dΩ is the reaction cross section for the photon polarization direction parallel (perpendicular) to the reaction plane. The measurements have been produced at the MAX-lab Nuclear Physics facility in the photon energy range E γ ∼ 40...55 M eV , using the tagged linearly polarized photon beam [2,3]. In the experiment, the protons were detected by an available ∆E − E telescope (CsI/SSD), which was not optimized for for measurements of the (⃗ γ, p) reactions with a high energy resolution.…”