New Techniques In Low Q2 Elastic Electron Proton Scattering Measurements And The Proton Radius Extraction
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New Techniques In Low Q2 Elastic Electron Proton Scattering Measurements And The Proton Radius Extraction
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Author : Yimin Wang (Scientist in physics)
language : en
Publisher:
Release Date : 2022
New Techniques In Low Q2 Elastic Electron Proton Scattering Measurements And The Proton Radius Extraction written by Yimin Wang (Scientist in physics) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
The proton charge radius is a fundamental property of the proton, sensitive to its charge distribution. The proton radius puzzle is the discrepancy between the muonic hydrogen spectroscopy measurement of 0.84 fm and the consensus of 0.88 fm from two traditional methods, electron-proton scattering and electronic hydrogen spectroscopy. A recent electron-proton scattering experiment, PRad, measured a smaller radius but also large electric form factor values within 0.02 ≤ Q2 ≤ 0.06 (GeV/c)2 conflicting with previous experiments. Motivated by those issues, we developed an innovative background-free target system, including a windowless gas jet target, a beam halo collimator and an active beam halo veto, to measure the proton electric form factor at momentum transfers of 0.01 ≤ Q2 ≤ 0.065 (GeV/c)2. The experiment was conducted in early 2020 at the three-spectrometer facility of the A1-collaboration at the Mainz Microtron in Mainz, Germany. Due to the COVID-19 lockdown, we measured the cross section only up to Q2 = 0.043 (GeV/c)2 with limited statistics. Although our form factor data cannot give a definitive answer to the form factor discrepancy and the proton radius puzzle yet, our work demonstrated the feasibility of such a background-free target design and we believe that further data taking with this technique can help to resolve the radius puzzle. In this work, we also study the extraction of the proton charge radius using non-parametric models. We demonstrate that the kernel ridge regression and the Gaussian process have similar levels of performance compared to the traditional function fitting approaches. Our extracted values from different data sets still show the discrepancy of the proton charge radius, supporting the point of view that the discrepancy originates from the data itself instead of the extraction method.
Precision Measurements Of Electron Proton Elastic Scattering Cross Sections At Large Q2
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Author : Longwu Ou
language : en
Publisher:
Release Date : 2019
Precision Measurements Of Electron Proton Elastic Scattering Cross Sections At Large Q2 written by Longwu Ou and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
The electromagnetic form factors are fundamental quantities characterizing the internal structure of the nucleon. Their measurements have provided significant insight into the spatial distribution and interaction of quarks inside the proton. The knowledge of high Q2 form factors proves essential in understanding the properties of quantum chromodynamics in the transition region from non-perturbative to perturbative behavior. It also provides important links to generalized parton distributions, which describe the three-dimensional structure of hadrons at the parton level. In view of the significant theoretical research activities in this field, high quality experimental data are crucial for providing stringent tests and benchmarks to guide and test different models. The form factors can be accessed in experiments by measuring elastic scattering of electrons off a hydrogen target. Experiment E12-07-108, which took place at the Thomas Jefferson National Accelerator Facility, conducted precise measurements of the unpolarized e-p elastic scattering cross section over a Q2 range of 0.6-16.5 GeV2 . This thesis presents the results for 7 kinematic settings with total uncertainties that are 1.5 times smaller than those of the existing data at large Q2 . The proton magnetic form factors were extracted using a parameterization of the form factor ratio obtained from recent polarized e-p scattering experiments. Comparisons to existing global and phenomenological fits are presented.
Measurements Of The Polarisation Of The Recoil Proton In Elastic Electron Proton Scattering At Q2
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Author : H. C. Kirkman
language : en
Publisher:
Release Date : 1970
Measurements Of The Polarisation Of The Recoil Proton In Elastic Electron Proton Scattering At Q2 written by H. C. Kirkman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1970 with categories.
A Measurement Of The Two Photon Exchange Effect In Elastic Electron Proton Scattering With Olympus
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Author : Rebecca Lynn Russell
language : en
Publisher:
Release Date : 2016
A Measurement Of The Two Photon Exchange Effect In Elastic Electron Proton Scattering With Olympus written by Rebecca Lynn Russell and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Elastic electron-proton scattering has long been the tool of choice for the study of the proton form factors, GE(Q 2 ) and GM(Q2 ), which describe the electric and magnetic distributions of the proton as a function of momentum transfer. Recent experiments, measuring the form factors from polarization observables in polarized elastic electron-proton scattering, have found values of the ratio GE(Q2 )/GM(Q2) at high Q2 that contradict the results from unpolarized measurements. A proposed explanation for this discrepancy is the unaccounted two-photon exchange radiative correction, which could affect the unpolarized measurements. As this effect is currently not possible to calculate in a model-independent way, the OLYMPUS experiment was designed to make a direct measurement of it by measuring the elastic positron-proton to electron-proton scattering cross section ratio. The experiment was run in 2012 at DESY using the BLAST spectrometer and the DORIS positron and electron beams at 2 GeV incident on a gaseous hydrogen target. To analyze the data, a careful reconstruction of the scattering events, detailed simulation of the experimental setup, and full radiative corrections to the measured cross sections were performed. Preliminary results for the experiment show a statistically significant two-photon exchange effect, increasing over the measurement range of 0.6 GeV2
Measuring The Lepton Sign Asymmetry In Elastic Electron Proton Scattering With Olympus
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Author : Axel William Schmidt
language : en
Publisher:
Release Date : 2016
Measuring The Lepton Sign Asymmetry In Elastic Electron Proton Scattering With Olympus written by Axel William Schmidt and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
OLYMPUS is a particle physics experiment that collected data in 2012 at DESY, in Hamburg, Germany, on the asymmetry between positron-proton and electron-proton elastic scattering cross sections. A non-zero asymmetry is evidence of hard two-photon exchange, which has been hypothesized to cause the discrepancy in measurements of the proton's electromagnetic form factors. Alternating electron and positron beams, accelerated to 2 GeV, were directed through a windowless, gaseous, hydrogen target, and the scattered lepton and recoiling proton were detected in coincidence using a large acceptance magnetic spectrometer. Determining the relative integrated luminosity between the electron and positron data sets was critical, and a new technique, involving multi-interaction events, was developed to achieve the desired sub-percent accuracy. A detailed Monte Carlo simulation was built in order to reproduce the convolution of systematic effects at every stage of the experiment. The first stage in the simulation was new radiative event generator, which permitted the full simulation of the non-trivial radiative corrections to the measurement. The analysis of the data and simulation showed that the lepton sign asymmetry rises by several percent between a momentum transfer of 0.5 GeV2 /c2 and 2.25 GeV2 /c2 . This rise as a function of increasing momentum transfer confirms that two photon exchange at least partially contributes to the proton form factor discrepancy.
Two Photon Exchange Effects In Elastic Electron Proton Scattering
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Author :
language : en
Publisher:
Release Date : 2013
Two Photon Exchange Effects In Elastic Electron Proton Scattering written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Two methods, Rosenbluth separation and polarization transfer, can be used to extract the proton form factor ratio [mu]p GEp/GMp, but they do not yield the same results. It is thought that the disagreement is due to two photon exchange corrections to the differential cross sections. High precision proton Rosenbluth extractions were carried out at 102 kinematics points spanning 16 values of momentum transfer Q2, from 0.40 to 5.76 GeV2. Reduced cross sections were found to 1.1% or better for Q2 less than 3 GeV2 increasing to 4% at 5.76 GeV2 The form factor ratios were determined to 1:5-3% for Q2
Physics Division Annual Report
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Author : Argonne National Laboratory. Physics Division
language : en
Publisher:
Release Date : 2003
Physics Division Annual Report written by Argonne National Laboratory. Physics Division and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Nuclear physics categories.
Measurements Of Elastic Electron Scattering From The Proton At High Momentum
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Author : Alan F. Sill
language : en
Publisher:
Release Date : 1987
Measurements Of Elastic Electron Scattering From The Proton At High Momentum written by Alan F. Sill and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with Elastic cross sections categories.
Precision Rosenbluth Measurement Of The Proton Elastic Electromagnetic Form Factors And Their Ratio At Q2
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Author :
language : en
Publisher:
Release Date : 2005
Precision Rosenbluth Measurement Of The Proton Elastic Electromagnetic Form Factors And Their Ratio At Q2 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Due to the inconsistency in the results of the mupGEp/GMp ratio of the proton, as extracted from the Rosenbluth and recoil polarization techniques, high precision measurements of the e-p elastic scattering cross sections were made at Q2 = 2.64, 3.20, and 4.10 GeV2. Protons were detected, in contrast to previous measurements where the scattered electrons were detected, which dramatically decreased-dependent systematic uncertainties and corrections. A single spectrometer measured the scattered protons of interest while simultaneous measurements at Q2 = 0.5 GeV2 were carried out using another spectrometer which served as a luminosity monitor in order to remove any uncertainties due to beam charge and target density fluctuations. The absolute uncertainty in the measured cross sections is 3̃% for both spectrometers and with relative uncertainties, random and slope, below 1% for the higher Q2 protons, and below 1% random and 6% slope for the monitor spectrometer. The extracted electric and magnetic form factors were determined to 4%-7% for GEp and 1.5% for GMp. The ratio mupGEp/GMp was determined to 4%-7% and showed mupGEp/GMp ̃1.0. The results of this work are in agreement with the previous Rosenbluth data and inconsistent with high-Q2 recoil polarization results, implying a systematic difference between the two techniques.
Gribov 90 Memorial Volume Field Theory Symmetry And Related Topics Proceedings Of The Memorial Workshop Devoted To The 90th Birthday Of V N Gribov
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Author : Yuri L Dokshitzer
language : en
Publisher: World Scientific
Release Date : 2021-04-20
Gribov 90 Memorial Volume Field Theory Symmetry And Related Topics Proceedings Of The Memorial Workshop Devoted To The 90th Birthday Of V N Gribov written by Yuri L Dokshitzer and has been published by World Scientific this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-04-20 with Science categories.
Vladimir Naumovich Gribov is one of the creators of modern theoretical physics. The concepts and methods that Gribov has developed in the second half of the 20th century became cornerstones of the physics of high energy hadron interactions (relativistic theory of complex angular momenta, a notion of the vacuum pole — Pomeron, effective reggeon field theory), condensed matter physics (critical phenomena), neutrino oscillations, and nuclear physics.His unmatched insights into the nature of the quantum field theory helped to elucidate, in particular, the origin of classical solutions (instantons), quantum anomalies, specific problems in quantization of non-Abelian fields (Gribov anomalies, Gribov horizon), and the role of light quarks in the color confinement phenomenon.The Memorial Workshop devoted to Gribov's 90th birthday was cancelled due to the coronavirus pandemic in 2020; however, this did not deter the collection of many new studies in challenging theoretical physics problems across a broad variety of topics, and shared memories about their colleague, great teacher and friend. The contributions of this memorial volume affirms the everlasting impact of Gribov's scientific heritage upon the physics of the 21st century.