Compton Scattering Polarimetry for the Determination of the Proton's Weak Charge Through Measurements of the Parity-Violating Asymmetry of 1H(e,e')p

Cornejo, J. C.

doi:10.2172/1330449

Cited by 4 publications

(4 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Details on the Compton polarimeter can be found in Ref. [5,6,10,11,12]. Since the electron detector provided the highest precision and most reliable measurements of the beam polarization from the Compton polarimeter, the results discussed here are from the electron detector only.…”

Section: The Hall-c Compton Polarimetermentioning

confidence: 99%

A novel comparison of Møller and Compton electron-beam polarimeters

et al. 2017

View full text Add to dashboard Cite

We have performed a novel comparison between electron-beam polarimeters based on Møller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents (< 5 µA) during the Q weak experiment in Hall C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 µA) operation of the Compton polarimeter. All measurements were found to be consistent within experimental uncertainties of 1% or less, demonstrating that electron polarization does not depend significantly on the beam current. This result lends confidence to the common practice of applying Møller measurements made at low beam currents to physics experiments performed at higher beam currents. The agreement between two polarimetry techniques based on independent physical processes sets an important benchmark for future precision asymmetry measurements that require sub-1% precision in polarimetry.

show abstract

Section: The Hall-c Compton Polarimetermentioning

confidence: 99%

A novel comparison of Møller and Compton electron-beam polarimeters

et al. 2017

View full text Add to dashboard Cite

show abstract

“…P : Details on the beam polarization analysis with the Møller polarimeter can be found in Josh Magee's dissertation [59] and with the Compton polarimeter in Amrendra Narayan's [60] and Juan Carlos Cornejo's dissertations [61]. In Run 1 only the Møller polarimeter was used for determining the beam polarization, because the Compton polarimeter was being commissioned.…”

Section: Uncertainties On a Epmentioning

confidence: 99%

Determination of the Kinematics of the Qweak Experiment and Investigation of an Atomic Hydrogen Moller Polarimeter

Gray

2018

View full text Add to dashboard Cite

The Q weak experiment has tested the Standard Model through making a precise measurement of the weak charge of the proton (Q p W ). This was done through measuring the parity-violating asymmetry for polarized electrons scattering off of unpolarized protons. The parity-violating asymmetry measured is directly proportional to the four-momentum transfer (Q 2 ) from the electron to the proton. The extraction of Q p W from the measured asymmetry requires a precise Q 2 determination. The Q weak experiment had a Q 2 = 24.8 ± 0.1 m(GeV 2 ) which achieved the goal of an uncertainty of ≤ 0.5%. From the measured asymmetry and Q 2 , Q p W was determined to be 0.0719 ± 0.0045, which is in good agreement with the Standard Model prediction. This puts a 7.5 TeV lower limit on possible "new physics". This dissertation describes the analysis of Q 2 for the Q weak experiment. Future parity-violating electron scattering experiments similar to the Q weak experiment will measure asymmetries to high precision in order to test the Standard Model. These measurements will require the beam polarization to be measured to sub-0.5% precision. Presently the electron beam polarization is measured through Møller scattering off of a ferromagnetic foil or through using Compton scattering, both of which can have issues reaching this precision. A novel Atomic Hydrogen Møller Polarimeter has been proposed as a non-invasive way to measure the polarization of an electron beam via Møller scattering off of polarized monatomic hydrogen gas. This dissertation describes the development and initial analysis of a Monte Carlo simulation of an Atomic Hydrogen Møller Polarimeter. Clearly good ol' Charlie Brown didn't know about graduate school because my dissertation is way more than a thousand words; but like him, there have been many people who have supported me. I would like to thank my adviser, David Armstrong, for all the help and guidance during my time at William & Mary. I am extremely grateful for all the time he has given to answering my questions and helping me through everything here. Thanks also to the members of my committee Dave Gaskell, Joshua Erlich, and Todd Avertt for help on various components of my work. I would also want to acknowledge my undergraduate teacher, adviser, and mentor, Michael Olson, without whom I would have never realized physics was interesting and pursued experimental nuclear physics. His advice and guidance at St. Norbert College and after has been invaluable and instrumental. I was given many opportunities for teaching, mentoring, and doing research and indispensable lab skills that I otherwise wouldn't have gotten. Also thanks for all the time dedicated to helping, working on research, and developing new labs for classes. I can't thank him enough for his amazing capacity for fostering confidence, giving perspective when needed, and the advice and support he has shared with me over the years and the ones to come. To the people whom I owe my existence, my parents David and Jola Gray. Thanks for all the unwavering support ov...

show abstract

“…The crystal was ultimately replaced with lead-tungstate (PbWO 4 ), which was cooled at 14 C to increase the signal-to-noise ratio. The photon detector analysis is discussed in full in [88].…”

Section: Compton Polarimetermentioning

confidence: 99%

A Measurement of the Parity-Violating Asymmetry in Aluminum and its Contribution to a Measurement of the Proton's Weak Charge

Magee

2016

View full text Add to dashboard Cite

The Q weak experiment, which ran at the Thomas Je↵erson National Accelerator Facility, made a precision measurement of the proton's weak charge, Q p W. The weak charge is extracted via a measurement of the parity-violating asymmetry in elastic electron-proton scattering from hydrogen at low momentum transfer (Q 2 =0.025 GeV 2). This result is directly related to the electroweak mixing angle, sin 2 (✓ W), a fundamental parameter in the Standard Model of particle physics. This provides a precision test sensitive to new, as yet unknown, fundamental physics. This dissertation focuses on two central corrections to the Q weak measurement: the target window contribution and sub-percent determination of the electron beam polarization. The aluminum target windows contribute approximately 30% of the measured asymmetry. Removal of this background requires precise measurements of both the elastic electron-aluminum scattering rate and its parity-violating asymmetry. The results reported here are the most precise measurement of the Q weak target dilution and asymmetry to date. The parity-violating asymmetry for the aluminum alloy was found to be 1.6174 ± 0.0704 (stat.) ± 0.0113 (sys.) parts-per-million. The first sub-percent precision polarization measurements made from the Hall C Møller polarimeter are also reported, with systematic uncertainties of 0.84%.

show abstract

Compton Scattering Polarimetry for the Determination of the Proton's Weak Charge Through Measurements of the Parity-Violating Asymmetry of 1H(e,e')p

Abstract: LIST OF FIGURES 2.1 An illustration of the particles included in the Standard Model. It shows the three main groups: leptons, quarks and Gauge bosons, the first two of which have three generations. The top right particle is the Higgs boson.

Cited by 4 publications

References 50 publications

A novel comparison of Møller and Compton electron-beam polarimeters

A novel comparison of Møller and Compton electron-beam polarimeters

Determination of the Kinematics of the Qweak Experiment and Investigation of an Atomic Hydrogen Moller Polarimeter

A Measurement of the Parity-Violating Asymmetry in Aluminum and its Contribution to a Measurement of the Proton's Weak Charge

Contact Info

Product

Resources

About