A cryogenic supersonic jet target for electron scattering experiments at MAGIX@MESA and MAMI

Grieser, S.; Bonaventura, D.; Brand, P.; Hargens, C.W.; Hetz, B.; Lessmann, Lukas; Westphälinger, C.; Khoukaz, A.

doi:10.1016/j.nima.2018.07.076

Cited by 19 publications

(14 citation statements)

References 21 publications

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“…For the focal-plane detector, a time projection chamber with open field cage and GEM readout is being developed (Caiazza et al, 2020;Gülker et al, 2019). Finally, a windowless internal gas-jet target (Grieser et al, 2018), which has already been commissioned at MAMI (Schlimme et al, 2021), will be used.…”

Section: Future Electron Scattering Experiments At Mainzmentioning

confidence: 99%

The proton charge radius

Gao,

Vanderhaeghen

2021

Preprint

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Nucleons (protons and neutrons) are the building blocks of atomic nuclei, and are responsible for more than 99% of the visible matter in the universe. Despite decades of efforts in studying its internal structure, there are still a number of puzzles surrounding the proton such as its spin, and charge radius. Accurate knowledge about the proton charge radius is not only essential for understanding how quantum chromodynamics (QCD) works in the non-perturbative region, but also important for bound state quantum electrodynamics (QED) calculations of atomic energy levels. It also has an impact on the Rydberg constant, one of the most precisely measured fundamental constants in nature. This article reviews the latest situation concerning the proton charge radius in light of the new experimental results from both atomic hydrogen spectroscopy and electron scattering measurements, with particular focus on the latter. We also present the related theoretical developments and backgrounds concerning the determination of the proton charge radius using different experimental techniques. We discuss upcoming experiments, and briefly mention the deuteron charge radius puzzle at the end. CONTENTS I. Introduction 1 II. The Proton Charge Radius Puzzle 3 A. Before the millennium 3 B. After the millennium 3 III. Elastic Electron-Proton Scattering 3 A. Introduction to Electron-Proton Scattering and Proton Electromagnetic Form Factors 3 B. Three-dimensional parton distributions 5 C. The nucleon transverse charge densities 7 D. GPDs and quark densities in longitudinal momentum and transverse position in a proton 10 E. Radii of quark distributions in a proton 12 F. Unpolarized electron-proton elastic scattering 16 G. Double-Polarization Elastic Electron-Proton Scattering 17 1. Spin-Dependent Asymmetry from p( e, e )p 17 2. Recoil Proton Polarization from p( e, e p) 18 H. Two-Photon-Exchange Contribution to Electron-Proton Scattering 18 I. Radiative Corrections in Electron Scattering 20 J. The Extraction of the Proton Charge Radius from Proton Electric Form Factor 21 IV. Atomic Hydrogen Spectroscopy 21 V. Modern lepton scattering experiments 24 A. Mainz 2010 24 B. JLab recoil polarization experiment 24 C. Mainz ISR measurements 24 D. The PRad experiment at JLab 25 E. Proton charge radius from modern analyses of proton electric form factor data 29 VI. Modern spectroscopic measurements 31 A. Muonic hydrogen spectroscopic experiments 31 B. Ordinary Hydrogen spectroscopic experiments 33 VII. Ongoing and upcoming experiments 35 A. The MUSE experiment at PSI 35 B. The COMPASS++/AMBER Experiment at CERN 35 C. The PRad-II experiment at Jefferson Lab 36 D. Future electron scattering experiments at Mainz 38 E. The ULQ 2 experiment at Tohoku University 39 VIII. The deuteron charge radius 39 IX. Conclusions 42 X. Acknowledgments 42 References 43

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Section: Future Electron Scattering Experiments At Mainzmentioning

confidence: 99%

The proton charge radius

Gao,

Vanderhaeghen

2021

Preprint

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“…The target for the MAGIX setup as shown in Fig. 8 is a cryogenic supersonic jet target that can be operated with most gases [4]. It was designed to achieve areal thicknesses of more than ρ areal ≈ 10 18 atoms/cm 2 when using hydrogen.…”

Section: Gas Jet Targetmentioning

confidence: 99%

“…The target including its technical details and operational parameters is described in Ref. [4] in more detail.…”

Section: Gas Jet Targetmentioning

confidence: 99%

“…While the MESA accelerator and the experimental site for the MAGIX setup are currently under construction, the gas jet target was already developed and tested at the University of Münster [4]. In 2017 it could be installed and successfully operated at the existing A1 multi-spectrometer setup at the Mainz Microtron (MAMI) electron accelerator in Mainz, Germany.…”

Section: Introductionmentioning

confidence: 99%

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Operation and characterization of a windowless gas jet target in high-intensity electron beams

Schlimme,

Aulenbacher,

Brand

et al. 2021

Preprint

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A cryogenic supersonic gas jet target was developed for the MAGIX experiment at the high-intensity electron accelerator MESA. It will be operated as an internal, windowless target in the energy-recovering recirculation arc of the accelerator with different target gases, e.g., hydrogen, deuterium, helium, oxygen, argon, or xenon. Detailed studies have been carried out at the existing A1 multi-spectrometer facility at the electron accelerator MAMI. This paper focuses on the developed handling procedures and diagnostic tools, and on the performance of the gas jet target under beam conditions. Considering the special features of this type of target, it proves to be well suited for a new generation of high-precision electron scattering experiments at high-intensity electron accelerators.

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“…measurement, several systematics can be avoided or reduced. The main improvement is the new target system, which will exchange the cryogenic cell with a hydrogen cluster-jet target [50], which puts no extraneous material in the main beam trajectory. In combination with an upstream collimator and and active veto to suppress electrons in the beam halo, the experiment aims for a completely background-free measurement.…”

Section: Future Scattering Experiments 51 Mainzmentioning

confidence: 99%

The proton radius puzzle – 9 years later

Bernauer

2020

EPJ Web Conf.

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High-precision measurements of the proton radius via scattering, electric hydrogen spectroscopy and muonic hydrogen spectroscopy do not agree on the level of more than 5 σ. This proton radius puzzle persists now for almost a decade. This paper gives a short summary over the progress in the solution of the puzzle as well as an overview over the planned experiments to finally solve this puzzle at the interface of atomic and nuclear physics.

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A cryogenic supersonic jet target for electron scattering experiments at MAGIX@MESA and MAMI

Cited by 19 publications

References 21 publications

The proton charge radius

The proton charge radius

Operation and characterization of a windowless gas jet target in high-intensity electron beams

The proton radius puzzle – 9 years later

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