Real-time calibration of the A4 electromagnetic lead fluoride (PbF2) calorimeter

Baunack, S.; Ríos, D. Balaguer; Capozza, L.; Diefenbach, J.; Frascaria, R.; Gläser, B.; Harrach, D. von; Imai, Yoshio; Kothe, R.; Kunne, R.; Lee, Jeong Han; Maas, F. E.; Espí, M. C. Mora; Morlet, M.; Ong, S.; Schilling, E.; Wiele, J. Van de; Weinrich, C.

doi:10.1016/j.nima.2011.02.099

Cited by 18 publications

(12 citation statements)

References 12 publications

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“…No magnetic spectrometer is used; the signal is separated from backgrounds using the energy deposition in the calorimeter. The calorimeter is an azimuthally symmetric array of 1022 PbF2 crystal, in seven rings covering scattered electron angles from either 30 • to 40 • (forward configuration) or 140 • to 150 • (backward configuration), acting as a total-absorption Cerenkov detector (51). The spectrum of energy deposited above a hardware threshold in clusters of 9 crystals is histogrammed using pipelined fast digitizer and the energy histograms are stored for each helicity state.…”

Section: Pva4mentioning

confidence: 99%

Parity-Violating Electron Scattering and the Electric and Magnetic Strange Form Factors of the Nucleon

Armstrong

McKeown

2012

Annu. Rev. Nucl. Part. Sci.

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Measurement of the neutral weak vector form factors of the nucleon provides unique access to the strange quark content of the nucleon. These form factors can be studied using parity-violating electron scattering. A comprehensive program of experiments has been performed at three accelerator laboratories to determine the role of strange quarks in the electromagnetic form factors of the nucleon. This article reviews the remarkable technical progress associated with this program, describes the various methods used in the different experiments, and summarizes the physics results along with recent theoretical calculations.

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Section: Pva4mentioning

confidence: 99%

Parity-Violating Electron Scattering and the Electric and Magnetic Strange Form Factors of the Nucleon

Armstrong

McKeown

2012

Annu. Rev. Nucl. Part. Sci.

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“…The LuMo consists of 8 water Cherenkov detectors and registers scattered electrons emitted at polar angles between 4.4 • and 10 • . To measure the transverse spin asymmetry in ep scattering, the electrons scattered between 30 • and 40 • are detected by a fast, totally absorbing, homogeneous electromagnetic calorimeter (EMC) composed of 1022 lead fluoride (PbF 2 ) crystals [70]. The PbF 2 crystals are installed symmetrically about the beam axis in 146 frames, each of which hosts 7 crystals.…”

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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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“…The experimental setup used in the A4 experiment [6,8,[20][21][22][23][24][25][26][27] at MAMI is described in detail in Ref. [8].…”

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confidence: 99%

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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Real-time calibration of the A4 electromagnetic lead fluoride (PbF2) calorimeter

Cited by 18 publications

References 12 publications

Parity-Violating Electron Scattering and the Electric and Magnetic Strange Form Factors of the Nucleon

Parity-Violating Electron Scattering and the Electric and Magnetic Strange Form Factors of the Nucleon

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

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