2026-09-20T00:11:47Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1070452026-06-17T14:46:02Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Richard Milner.
Henderson, Brian Scott
Massachusetts Institute of Technology. Department of Physics.
Massachusetts Institute of Technology. Department of Physics
2017-02-22T19:00:57Z
2017-02-22T19:00:57Z
2016
2016
http://hdl.handle.net/1721.1/107045
970814633
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 275-288).
Measurements of the ratio of the proton elastic form factors ([mu]pGe/Gm) using Rosenbluth separation and those using polarization-based techniques show a strong discrepancy, which has persisted both in modern experimental results and in re-analyses of previous data. The most widely accepted hypothesis to explain this discrepancy is the treatment of the contributions from hard two-photon exchange (TPE) to elastic electron-proton scattering in the radiative corrections applied to the Rosenbluth separation measurements. Calculations of the hard TPE contribution are highly model dependent, but the effect may be measured experimentally with a precise determination of the ratio of the positron-proton and electron-proton elastic scattering cross sections. The OLYMPUS experiment collected approximately 4 fb-1 of e+p and e-p scattering data at the DORIS storage ring at DESY in 2012, with the goal of measuring the elastic [sigma]e+p/[sigma]e-p ratio over the kinematic range (0.4 < c < 0.9), (0.6 < Q2 < 2.2) GeV2 /c 2 at a fixed lepton beam energy of 2.01 GeV. The detector for the OLYMPUS experiment consisted of refurbished elements of the Bates Large Acceptance Spectrometer Toroid (BLAST) surrounding an internal gaseous hydrogen target, with the addition of multiple systems for the monitoring of the luminosity collected by the experiment. A detailed simulation of the experiment was developed to account for both radiative corrections and various systematic effects. This work presents preliminary results from the OLYMPUS data, demonstrating that the elastic [sigma]e+p/[sigma]e-p ratio rises to several percent at [epsilon] ~~ 0.4 and indicating a significant contribution from TPE to e± p scattering. Additionally, the value of [sigma]e+p/[sigma]e-p has been measured to unprecedented precision at [epsilon] = 0.98, which provides a valuable normalization point for other experimental data.
by Brian Scott Henderson.
Ph.D.
288 pages
eng
Massachusetts Institute of Technology
MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.
http://dspace.mit.edu/handle/1721.1/7582
Physics.
A precision measurement of the e⁺p/e⁻p elastic scattering cross section ratio at the OLYMPUS experiment
Thesis
application/pdf
Publication
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<Abstract>Measurements of the ratio of the proton elastic form factors ([mu]pGe/Gm) using Rosenbluth separation and those using polarization-based techniques show a strong discrepancy, which has persisted both in modern experimental results and in re-analyses of previous data. The most widely accepted hypothesis to explain this discrepancy is the treatment of the contributions from hard two-photon exchange (TPE) to elastic electron-proton scattering in the radiative corrections applied to the Rosenbluth separation measurements. Calculations of the hard TPE contribution are highly model dependent, but the effect may be measured experimentally with a precise determination of the ratio of the positron-proton and electron-proton elastic scattering cross sections. The OLYMPUS experiment collected approximately 4 fb-1 of e+p and e-p scattering data at the DORIS storage ring at DESY in 2012, with the goal of measuring the elastic [sigma]e+p/[sigma]e-p ratio over the kinematic range (0.4 < c < 0.9), (0.6 < Q2 < 2.2) GeV2 /c 2 at a fixed lepton beam energy of 2.01 GeV. The detector for the OLYMPUS experiment consisted of refurbished elements of the Bates Large Acceptance Spectrometer Toroid (BLAST) surrounding an internal gaseous hydrogen target, with the addition of multiple systems for the monitoring of the luminosity collected by the experiment. A detailed simulation of the experiment was developed to account for both radiative corrections and various systematic effects. This work presents preliminary results from the OLYMPUS data, demonstrating that the elastic [sigma]e+p/[sigma]e-p ratio rises to several percent at [epsilon] ~~ 0.4 and indicating a significant contribution from TPE to e± p scattering. Additionally, the value of [sigma]e+p/[sigma]e-p has been measured to unprecedented precision at [epsilon] = 0.98, which provides a valuable normalization point for other experimental data.</Abstract>
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