Author: Martin LöwePublisher:
ISBN:
Category :
Languages : de
Pages :
Book Description
Measurement of positron proton scattering at Q2
Author: Martin LöweMeasurement of Positron Proton Scattering at Q2
Author: Martin LöweMeasurement of the Positron-proton Neutral Current Deep Inelastic Scattering Double Differential Cross Section at High Q2
Author: Haibo ZhangA Measurement of the Two-photon Exchange Effect in Elastic Electron-proton Scattering with OLYMPUS
Author: Rebecca Lynn RussellPublisher:
ISBN:
Category :
Languages : en
Pages : 190
Book Description
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
New Techniques in Low-Q2 Elastic Electron-proton Scattering Measurements and the Proton Radius Extraction
Author: Yimin Wang (Scientist in physics)Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
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.
International Conference on Elastic and Diffractive Scattering : Protvino, Russia, 28 June - 2 July 1999 : Proceedings of the VIIIth Blois Workshop
Author: Vladimir A. PetrovPublisher: World Scientific
ISBN: 9789810241186
Category : Science
Languages : en
Pages : 412
Book Description
This book contains various experimental and theoretical reports on the status and prospects of one of the most interesting and difficult areas of modern high energy physics ? elastic and diffractive scattering. One can find here general trends and problems, and original ideas on particle interactions and structure.
Deep Inelastic Positron-Proton Scattering in the High-Momentum-Transfer Regime of HERA
Author: Ulrich F. KatzPublisher: Springer
ISBN: 354045019X
Category : Science
Languages : en
Pages : 243
Book Description
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.
Elastic And Diffractive Scattering: Proceedings Of The International Conference On The Viiith Blois Workshop
Author: A V ProkudinPublisher: World Scientific
ISBN: 9814494046
Category : Science
Languages : en
Pages : 406
Book Description
This book contains various experimental and theoretical reports on the status and prospects of one of the most interesting and difficult areas of modern high energy physics — elastic and diffractive scattering. One can find here general trends and problems, and original ideas on particle interactions and structure.
From Parity Violation to Hadronic Structure and more
Author: Serge KoxPublisher: Springer Science & Business Media
ISBN: 3540263454
Category : Science
Languages : en
Pages : 198
Book Description
Almost 50 years after the proposal of Lee and Young in 1956 to test the hypothesis of parity violation in weak interactions and the subsequent experimental verification of parity violation by C. S. Wu, parity violation has today become a useful property of weak interactions. This is due to the fact that the focus nowadays has changed: parity violation in weak interactions is no more a topic of investigation but is used as a tool in many different fields ranging from nuclear physics to the search for the hidden extra dimensions requested by string theory. For our first workshop which took place June 5-8, 2002, at the Institut fiir Ke- physik of the Johannes Gutenberg-Universitat Mainz, we concentrated on the in vestigation of the strangeness contribution in the nucleon. This book contains the refereed and selected papers of the second workshop "From Parity Violation to Hadron Structure and more (Part II)", which took place June 8-11, in the Labo- toire de Physique Subatomique et de Cosmologie, in Grenoble. These papers appear in EPJAdirect, the electronic-only part of EPJA, and they are accessible without restrictions. They will also appear in printed form and can be ordered through Springer. The excellent presentations show the dramatic and steady progress in the accuracy of measured parity violating asymmetries over the last few years.
Positron-proton Scattering
Author: Andrew Arnold BrowmanPublisher:
ISBN:
Category :
Languages : en
Pages : 318
Book Description
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).