A high power liquid hydrogen target for the Mainz A4 parity violation experiment

Altarev, I.; Schilling, E.; Baunack, S.; Capozza, L.; Diefenbach, J.; Grimm, K.; Hammel, T.; Harrach, D. von; Imai, Yoshio; Kabuß, E. M.; Kothe, R.; Lee, Jeong Han; Ginja, A. Lopes; Maas, F. E.; Lorente, A. Sánchez; Stephan, G.; Weinrich, C.

doi:10.1016/j.nima.2006.03.022

Cited by 18 publications

(6 citation statements)

References 16 publications

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“…In order to test and understand any helicity-correlated systematic effects, a half-wave plate, which introduces an extra spin flip, is placed before the GaAs crystal for about 50% of the data-taking time. MAMI delivers continuous wave polarized electron beams with an intensity of 20 µA, impinging on a 10 cm long liquid hydrogen target [68]. This gives a luminosity of L = 5.3 × 10 37 cm −2 s −1 , which is monitored with a luminosity monitor (LuMo) [69].…”

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confidence: 99%

Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range

Gou¹,

Arvieux²,

Aulenbacher³

et al. 2020

Phys. Rev. Lett.

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We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, A ep ⊥ , at five beam energies from 315.1 MeV to 1508.4 MeV and at a scattering angle of 30 • < θ < 40 • . The covered Q 2 values are 0.032, 0.057, 0.082, 0.218, 0.613 (GeV/c) 2 . The measurement clearly indicates significant inelastic contributions to the two-photon-exchange (TPE) amplitude in the low-Q 2 kinematic region. No theoretical calculation is able to reproduce our result. Comparison with a calculation based on unitarity, which only takes into account elastic and πN inelastic intermediate states, suggests that there are other inelastic intermediate states such as ππN, KΛ and ηN. Covering a wide energy range, our new high-precision data provide a benchmark to study those intermediate states.PACS numbers: 13.60. Fz, 11.30.Er, 13.40.Gp As a probe of hadron structure, electron scattering has two advantages: the structurelessness of the electron and the smallness of the electromagnetic coupling (α ≈ 1/137). The small coupling allows to expand the scattering amplitude in powers of α and to interpret experiments within the one-photon-exchange (Born) approximation. This leading order approximation enables a straightforward extraction of the electromagnetic form factors with the Rosenbluth separation technique [1]. For a precise extraction of the form factors it is necessary to include higher order quantum corrections [2,3]. Importantly, most of those corrections do not alter the Rosenbluth formula in that they contribute an overall factor to the cross section.The contribution that is expected to break this pattern [4,5] is the two-photon-exchange (TPE) diagram depicted in Fig. 1. For a long time the TPE effects have eluded direct experimental searches [6][7][8]. The situation changed when a striking discrepancy between the Rosenbluth separation [9, 10] and the polarization transfer [11?-13] data on the proton form factor ratio µ p G E /G M was observed. To evaluate the TPE corrections one needs to model the doubly-virtual Compton scattering (VVCS) in the most general kinematics. This involves calculating the two-current correlator with inclusive hadronic intermediate states. The full account of the inclusive intermediate states contribution can be made in the limited nearforward kinematics [15]. Beyond the forward kinematics, it is only possible to account for the elastic [16][17][18][19] or the pion-nucleon (πN) [20] intermediate state contributions.The theoretical framework for calculating the TPE contributions plays an important role in evaluating the two-boson-exchange corrections to precision low-energy tests of the Standard Model (SM) in the electroweak sector. The proton polarizability contribution to the fine structure of light muonic atoms stems from the TPE diagram and is a substantial ingredient [21] in the proton radius puzzle, the 7σ discrepancy in the value of the proton charge radius extracted from hydrogen spectroscopy [22] and electron-proton (ep) scattering [23] on one hand, an...

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confidence: 99%

Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range

Gou¹,

Arvieux²,

Aulenbacher³

et al. 2020

Phys. Rev. Lett.

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“…Once the beam reaches the A4 experiment, it passes with a luminosity of 1.4 × 10 38 cm −2 s −1 through a liquid deuterium target [26]. The scattered electrons are registered in a homogeneous, segmented, totally absorbing electromagnetic PbF 2 calorimeter [22] that is mounted on a rotatable platform and can be operated at both forward and backward angles.…”

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Measurement of the parity violating asymmetry in the quasielastic electron-deuteron scattering and improved determination of the magnetic strange form factor and the isovector anapole radiative correction

et al. 2016

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“…To estimate the number of events for single kaon production we have considered a luminosity of 5 × 10 37 s −1 cm −2 for MAMI, that corresponds to a 10 cm liquid hydrogen target at an electron beam current of 20 µA as described in [29]. For TJNAF, we take a luminosity of 5 × 10 38 s −1 cm −2 that corresponds to a current of 100 µA and a larger liquid hydrogen target [30] that has been used on the measurement of parity violating electron proton scattering.…”

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confidence: 99%

Charged lepton induced one kaon production off the nucleon

et al. 2013

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We study single kaon production off the nucleon induced by electrons (positrons) i.e. e − (e + ) + N → ν e (ν e ) +K(K) + N ′ at low energies. The possibility of observing these processes with the high luminosity beams available at TJNAF and Mainz is discussed, taking into account that the strangeness conserving electromagnetic reactions have a higher energy threshold forK(K) production. The calculations are done using a microscopic model that starts from the SU(3) chiral Lagrangians, includes background terms and the resonant mechanisms associated to the lowest lying resonance Σ * (1385).

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A high power liquid hydrogen target for the Mainz A4 parity violation experiment

Cited by 18 publications

References 16 publications

Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range

Study of Two-Photon Exchange via the Beam Transverse Single Spin Asymmetry in Electron-Proton Elastic Scattering at Forward Angles over a Wide Energy Range

Measurement of the parity violating asymmetry in the quasielastic electron-deuteron scattering and improved determination of the magnetic strange form factor and the isovector anapole radiative correction

Charged lepton induced one kaon production off the nucleon

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