Measurement Of Positron Proton Scattering At Q2
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Measurement Of Positron Proton Scattering At Q2
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Author : Martin Löwe
language : de
Publisher:
Release Date : 1996
Measurement Of Positron Proton Scattering At Q2 written by Martin Löwe and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with categories.
Measurement Of Positron Proton Scattering At Q2
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Author : Martin Löwe
language : en
Publisher:
Release Date : 1996
Measurement Of Positron Proton Scattering At Q2 written by Martin Löwe and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with categories.
Measurement Of The Positron Proton Neutral Current Deep Inelastic Scattering Double Differential Cross Section At High Q2
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Author : Haibo Zhang
language : en
Publisher:
Release Date : 1998
Measurement Of The Positron Proton Neutral Current Deep Inelastic Scattering Double Differential Cross Section At High Q2 written by Haibo Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 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
Towards A Resolution Of The Proton Form Factor Problem
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Author :
language : en
Publisher:
Release Date : 2015
Towards A Resolution Of The Proton Form Factor Problem written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
There is a significant discrepancy between the values of the proton electric form factor, GpE, extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of GpE from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (epsilon) and momentum transfer (Q2) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing [epsilon] at Q2=1.45 GeV2. This measurement is consistent with the size of the form factor discrepancy at Q2≈1.75 GeV2 and with hadronic calculations including nucleon and Delta intermediate states, which have been shown to resolve the discrepancy up to 2-3 GeV2.
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.
Deep Inelastic Positron Proton Scattering In The High Momentum Transfer Regime Of Hera
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Author : Ulrich F. Katz
language : en
Publisher: Springer
Release Date : 2003-07-01
Deep Inelastic Positron Proton Scattering In The High Momentum Transfer Regime Of Hera written by Ulrich F. Katz and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003-07-01 with Science categories.
About three decades after the first experiments on deep inelastic lepton hadron scattering began to investigate the structure of hadrons, the history of this fruitful field of particle physics continues in the broad spectrum of research performed at the electron and positron proton collider HERA at DESY, where the multipurpose detectors ZEUS and H1 access ep scattering at a center of mass energy of 300 GeV and explore as yet uncharted kinematic realms of deep inelastic scattering. After the first years of data taking at HERA, each of the experiments has collected a total of roughly 40 pb 1 of e+p data, yielding sensitivity to deep inelastic e+p interactions at high four momentum transfers, Q2, where typi cal cross sections drop into the subpicobarn regime. This kinematic domain is characterized by electroweak unification, manifesting itself most markedly in the neutral and charged current cross sections, which approach an equal order of magnitude as Q2 rises above the square of the W and Z masses. Consequently, HERA allows, for the first time, studies of both types of pro cesses simultaneously with the same initial state conditions and in the same detector, and thus we can investigate the interplay of electroweak and strong forces governing the respective cross sections.
A Measurement Of Beauty Production In High Energy Positron Proton Scattering
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Author : Jürgen Kroseberg
language : en
Publisher:
Release Date : 2002
A Measurement Of Beauty Production In High Energy Positron Proton Scattering written by Jürgen Kroseberg and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.
Positron Proton Scattering
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Author : Andrew Arnold Browman
language : en
Publisher:
Release Date : 1964
Positron Proton Scattering written by Andrew Arnold Browman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1964 with categories.
The importance of two-photon exchange in elastic electron-proton scattering was investigated by measuring the ratio of positron-proton to electron-proton scattering. Four momentum transfers as large as 0.756 (BeV/c) to the 2nd power (19.5 F to the -2nd power) were used. The data indicate that two-photon effects are 4.0 = 1.5% larger than those predicted by the radiative corrections at the highest momentum transfers attained in these experiments. The two-photon corrections predicted, using a static charge distribution, fit the data well at lower momentum transfers and forward angles but appear to be small at higher momentum transfers and backward angles. (Author).
Demonstration Of A Novel Technique To Measure Two Photon Exchange Effects In Elastic E P Scattering
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Author :
language : en
Publisher:
Release Date : 2013
Demonstration Of A Novel Technique To Measure Two Photon Exchange Effects In Elastic E P 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.
The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in e"p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e"p comparisons, which has the potential to make precise measurements over a broad range in Q2 and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q2 and scattering angle. Nonetheless, this measurement yields a data sample for e"p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the difference between the incoming electron and positron beams. This systematic effect leads to the largest uncertainty in the final ratio of positron to electron scattering: R=1.027"0.005"0.05 for Q2=0.206 GeV2 and 0.830 d"[epsilon] d"0.943. We have demonstrated that the tertiary e" beam generated using this technique provides the opportunity for dramatically improved comparisons of e"p scattering, covering a significant range in both Q2 and scattering angle. Combining data with different chicane polarities will allow for detailed studies of the difference between the incoming e+ and e- beams.