Difference between revisions of "Parity Quality Beam"

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PQB
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* <span style="font-size:150%"> '''[[Accelerator PQB Meetings]]''' </span>
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[[file:PQB_reflection.jpg|right|400px|]]
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A significant portion of the experiments performed at Jefferson Lab require a polarized electron beam. A subset of these are parity violation experiments which have exceptionally stringent requirements on the quality of the electron beam. As the sign of the electron beam helicity reverses at the target of the experiment no other measurable quantity of the electron beam may change. This includes the beam intensity, polarization, position, angle, energy or spot size.
 +
 
 +
To ensure this beam quality, a significant effort occurs at the polarized electron source, where the laser beam and electron photogun combine to produce the intended electron beam. Also significant is the ability to accelerate the beam to high energy while transporting it to the experimental target, all while maintaining a parity quality electron beam (PQB).
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='''Parity Violation'''=
 +
Discussion of parity violation can be found at NIST: ''The Fall of Parity'': [http://www.nist.gov/pml/general/parity/index.cfm]
 +
 
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='''Accelerator Setup to Run Parity Violation'''=
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An overview of how parity-violating electron scattering experiments are performed at CEBAF, P.A. Adderley et al.,
 +
Nuclear Inst. and Methods in Physics Research, A 1046 (2023) 167710. [https://doi.org/10.1016/j.nima.2022.167710]
 +
 
 +
 
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='''Parity Violation Experiments'''=
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 +
# JLab Hall A Parity Experiments (HAPPEx, PREx, C-REx, PVDIS): [http://hallaweb.jlab.org/parity/]
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# JLab Hall C G0 Experiment
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# JLab Hall C QWeak Experiment: [http://www.jlab.org/qweak/]
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# JLab Hall A Møller Experiment: [https://moller.jlab.org/moller_root/]
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# Mainz A4 Experiment
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* The following table lists what has been achieved and the future requirements on PQB: [[media:PV_Table_Dec2022.pdf]] [[media:PV_Table_Dec2022.docx]] [[media:PV_Experiments_Dec2022.pdf]] [[media:PV_Experiments_Dec2022.pptx]]
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[[file:PV_Experiments_Dec2022.jpg|center|800px|]]
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* '''Table References:'''
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# Measurement of the neutral weak form factors of the proton, K. A. Aniol et al., Phys. Rev. Lett. 82, 1096 (1999). [https://doi.org/10.1103/PhysRevLett.82.1096]
 +
# New Measurement of Parity Violation in Elastic Electron-Proton Scattering and Implications for Strange Form Factors. K. A. Aniol et al., Phys. Lett. B 509, 211 (2001). [https://doi.org/10.1016/S0370-2693(01)00446-4]
 +
# Parity-violating Electroweak Asymmetry in e ⃗p Scattering. K. A. Aniol et al., Phys. Rev. C 69, 065501 (2004). [https://doi.org/10.1103/PhysRevC.69.065501]
 +
# Strange-Quark Contributions to Parity-Violating Asymmetries in the Forward G0 Electron-Proton Scattering Experiment, D. S. Armstrong et al. Phys. Rev. Lett. 95, 092001 (2005). [https://doi.org/10.1103/PhysRevLett.95.092001]
 +
# Parity-Violating Electron Scattering from 4He and the Strange Electric Form Factor of the Nucleon, K. A. Aniol et al., Phys. Rev. Lett. 96, 022003 (2006). [https://doi.org/10.1103/PhysRevLett.96.022003]
 +
# Constraints on the nucleon strange form factors at Q2 ∼ 0.1 GeV2. K. A. Aniol et al., Phys. Lett. B 635, 275 (2006). [https://doi.org/10.1016/j.physletb.2006.03.011]
 +
# Precision Measurements of the Nucleon Strange Form Factors at Q2∼0.1 GeV2 , A. Acha et al., Phys. Rev. Lett. 98, 032301 (2007). [https://doi.org/10.1103/PhysRevLett.98.032301]
 +
# Strange Quark Contributions to Parity-Violating Asymmetries in the Backward Angle G0 Electron Scattering Experiment, D. Androić et al., Phys. Rev. Lett. 104, 012001 (2010). [https://doi.org/10.1103/PhysRevLett.104.012001]
 +
# New Precision Limit on the Strange Vector Form Factors of the Proton, Z. Ahmed et al., Phys. Rev. Lett. 108, 102001 (2012). [https://doi.org/10.1103/PhysRevLett.108.102001]
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# Measurements of Parity-Violating Asymmetries in Electron-Deuteron Scattering in the Nucleon Resonance Region. D. Wang et al., Phys. Rev. Lett. 111, 082501 (2013). [https://doi.org/10.1103/PhysRevLett.111.082501]
 +
# Measurement of parity violation in electron-quark scattering. D. Wang et al., Nature 506, 67 (2014). [https://doi.org/10.1038/nature12964]
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# Measurement of parity-violating asymmetry in electron-deuteron inelastic scattering. D. Wang et al., Phys. Rev. C 91, 045506 (2015). [https://doi.org/10.1103/PhysRevC.91.045506]
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# Measurement of the Neutron Radius of 208Pb through Parity Violation in Electron Scattering, S. Abrahamyan et al., Phys. Rev. Lett. 108, 112502 (2012). [https://doi.org/10.1103/PhysRevLett.108.112502]
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# First Determination of the Weak Charge of the Proton, D. Androic et al., Phys. Rev. Lett. 111, 141803 (2013). [https://doi.org/10.1103/PhysRevLett.111.141803]
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# Precision measurement of the weak charge of the proton. D. Androi´c et al., Nature 557, 207 (2018). [https://doi.org/10.1038/s41586-018-0096-0]
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# Parity-violating inelastic electron-proton scattering at low Q2 above the resonance region, D. Androić et al., Phys. Rev. C 101, 055503 (2020). [https://doi.org/10.1103/PhysRevC.101.055503]
 +
# Determination of the 27Al Neutron Distribution Radius from a Parity-Violating Electron Scattering Measurement, D. Androić et al., Phys. Rev. Lett. 128, 132501 (2022). [https://doi.org/10.1103/PhysRevLett.128.132501]
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# Accurate Determination of the Neutron Skin Thickness of 208Pb through Parity-Violation in Electron Scattering, D. Adhikari et al., Phys. Rev. Lett. 126, 172502 (2021). [https://doi.org/10.1103/PhysRevLett.126.172502]
 +
# Precision Determination of the Neutral Weak Form Factor of 48Ca, D. Adhikari et al., Phys. Rev. Lett. 129, 042501 (2022). [https://doi.org/10.1103/PhysRevLett.129.042501]
 +
# The MOLLER Experiment: An Ultra-Precise Measurement of the Weak Mixing Angle Using Møller Scattering, J. Benesch et al., arXiv:1411.4088. [https://doi.org/10.48550/arXiv.1411.4088]
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# SoLID (Solenoidal Large Intensity Device), Updated Preliminary Conceptual Design Report, The SoLID Collaboration, November 2019. [https://solid.jlab.org/DocDB/0002/000282/001/solid-precdr-2019Nov.pdf]
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='''Selected References'''=
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* ''Experimental Test of Parity Conservation in Beta Decay''.
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C. S. Wu et al., Phys. Rev. '''105''' (1957) 1413 [http://dx.doi.org/10.1103/PhysRev.105.1413] [[media:PhysRev.105.1413.pdf]]
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* ''Parity-Violating Electron Scattering and the Electric and Magnetic Strange Form Factors of the Nucleon''.
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D. S. Armstrong and R. D. McKeown, Annu. Rev. Nucl. Part. '''62''' (2012) 337 [http://dx.doi.org/10.1146/annurev-nucl-102010-130419] [[media:annurev-nucl-102010-130419.pdf]]
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* ''The Q<sub>weak</sub> experimental apparatus''.
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T. Allison et al., Nucl. Instr. and Meth. A '''781''' (2015) 105 [http://dx.doi.org/10.1016/j.nima.2015.01.023] [[media:NuclInstrumMethA.781.105.pdf]]
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='''Injector PQB Setup'''=
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* ''SLAC's polarized electron source laser system and minimization of electron beam helicity correlations for the E-158 parity violation experiment''.
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T. B. Humensky et al., Nucl. Instr. and Meth. A '''521''' (2004) 261 [http://dx.doi.org/10.1016/j.nima.2003.09.065] [[media:NuclInstrMethA.521.261.pdf]]
 +
* ''Helicity correlated asymmetries caused by optical imperfections''.
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K. Aulenbacher, Euro. Phys. J. A '''32''' (2007) 543 [http://dx.doi.org/10.1140/epja/i2006-10397-8] [[media:EuroPhysJA.32.543.pdf]]
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-----
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-----
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='''Mailing List'''=
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* Accelerator Parity Quality Beam mailing list: acc_parity@jlab.org
 +
* Web page for users of mailing list is: [https://mailman.jlab.org/mailman/listinfo/acc_parity]
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 +
-----
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-----
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= <span style="font-size:150%"> '''MOLLER PQB''' </span>=
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* '''MOLLER Document Database:''' [https://moller.jlab.org/cgi-bin/DocDB/public/DocumentDatabase]
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* '''MOLLER Technical Design Report:''' [https://moller.jlab.org/cgi-bin/DocDB/public/ShowDocument?docid=998]
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* '''MOLLER Beam Requirements (March 22, 2023):''' [[media:MOLLER_beam_requirements_22March2023.pdf]]
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* '''MOLLER Accelerator Jobs:''' [[media:MOLLER_Accelerator_MainJobs_details_October2023.pdf]] [[media:MOLLER_Accelerator_MainJobs_details_October2023.docx]]<br />
 +
* '''MOLLER Beam Studies (with BSList #):''' [[media:MOLLER_BeamStudies_October2023.pdf]] [[media:MOLLER_BeamStudies_October2023.xlsx]]
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* '''MOLLER Accelerator Tasks Planner:''' [[media:MOLLER_Accelerator_Tasks_Planner.xlsx]]  [[media:MOLLER_Accelerator_Tasks_Planner.pdf]]
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*  '''MOLLER Accelerator Scopre-of-work:''' [[media:MOLLER_Accelerator_ScopeOfWork.xlsx]]  [[media:MOLLER_Accelerator_ScopeOfWork.pdf]]
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** List of beam studies to be done before MOLLER (C. Palatchi, November 9, 2022): [[media:MOLLER_PQBlist.pdf]] [[media:MOLLER_PQBlist.docx]]
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** New Settings for Helicity Generator Board: [[media:MOLLER_HelicityBoard_SettingsRequest.pdf]] [[media:MOLLER_HelicityBoard_SettingsRequest.docx]]
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** Helicity Generator Boards Inventory: [[media:Helicity_Generator_Boards_Inventory.xlsx]]
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** '''[[New RTP HV Driver]]'''
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** Upgrade IA System: [[media:MOLLER_IA_Requiremnet_Document.pdf]] [[media:MOLLER_IA_Requiremnet_Document.docx]]
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** Laser Table Grounding: [[media:MOLLER_Ground_Requiremnet_Document.pdf]] [[media:MOLLER_Ground_Requiremnet_Document.docx]]
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** Upgrade Helicity Magnets Control: [[media:MOLLER_HelicityMagnets_Upgrade_Requiremnet_Documnet.pdf]] [[media:MOLLER_HelicityMagnets_Upgrade_Requiremnet_Documnet.docx]]
 +
** Functional Requirements for the MOLLER Polarization Orientation Feedback Control (K. Paschke, October 30, 2023): [[media:PolarizationFeedback_October2023.pdf]]
 +
* '''CEBAF Operations StayTreat - Planning for FY24-FY27 (June 6, 2023)''': [[media:MOLLER_Accelerator_Tasks_StayTreat_June2023.pdf]]  [[media:MOLLER_Accelerator_Tasks_StayTreat_June2023.pptx]] 
 +
* '''KLF Phase I ERR (August 2, 2023) - Simultaneous Beam Delivery with Parity Quality Beam:''' [[media:KLF_Phase_I_ERR_MOLLER_suleiman.pdf]]  [[media:KLF_Phase_I_ERR_MOLLER_suleiman.pptx]]
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* '''Redesigning the Jefferson Lab Hall A beam line for high precision parity experiments,''' J. Benesch and Y. Roblin 2021 JINST 16 T12007: [[media:Benesch_2021_J._Inst._16_T12007.pdf]]
 +
 
 +
=='''Helicity Decoder Board'''==
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 +
* Helicity Decoder Board (December 1, 2020): [[media:HelicityDecoderBoard.pdf]] [[media:HelicityDecoderBoard.pptx]]
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* Conceptual Specs for Helicity Decoder Board (P. M. King, Ohio University, November 20, 2020): [[media:.pdf]]
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* DAQ Requirement on Helicity Decoder (P. M. King, Ohio University, December 1, 2020): [[media:.pdf]]
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* Programming the Helicity Decoder Module (Ed Jastrzembski, FE-DAQ Group, V7 - 9/25/2023): [[media:Programming_Helicity_Decoder_Module-V7.pdf]]
 +
* Helicity Decoder Boards Inventory: [[media:Helicity_Decoder_Boards_Inventory.xlsx]]
 +
 
 +
=='''Synchrotron Radiation'''==
 +
 
 +
* Synchrotron Radiation from Wikipedia, the free encyclopedia: [http://en.wikipedia.org/wiki/Synchrotron_radiation]
 +
* Synchrotron Radiation: [[media:CASA_SynchrotronRadiation.pdf]]
 +
* US Particle Accelerator School lecture: [[media:USPAS_lecture_Barletta.pdf]]
 +
* Synchrotron Radiation at 11 GeV and its adverse effect on PQB
 +
 
 +
=='''Collaboration Presentations'''==
 +
 
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* Møller Collaboration Meeting January 23, 2015: [[media:Moller_23Jan15_poelker.pdf]] [[media:Moller_23Jan15_poelker.pptx]]
 +
# Beam Monitoring: [[media:Moller_23Jan15_pitt.pdf]]
 +
 
 +
=='''Other Presentations'''==
 +
 
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* ECT* Workshp, ''CEBAF Polarized Beam for Parity Violation Experiments in the 12 GeV era'', Arne Freyberger (August 4, 2016): [[media:ECT_CEBAF_PolarizedBeams_and_ParityViolation_August2016.pdf]]
 +
 
 +
-----
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-----
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='''PREx-II PQB'''=
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* PREX-II Beam Requirements: [[media:PREX-II_Beam_Requirements_July2019.pdf]]
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-----
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-----
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='''QWeak PQB'''=
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=='''Accelerator Meetings'''==
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* Accelerator PQB Meeting August 13, 2009: [[media:PQB_Meeting_13Aug09.pdf]] [[media:PQB_Meeting_13Aug09.pptx]]
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* Accelerator PQB Meeting June 2, 2009: [[media:PQB_Meeting_fHelReversal_02June09.pdf]] [[media:PQB_Meeting_fHelReversal_02June09.pptx]]
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* Accelerator PQB Meeting June 2, 2009: [[media:PQB_Meeting_StatAna_02June09.pdf]] [[media:PQB_Meeting_StatAna_02June09.pptx]]
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* Accelerator PQB Meeting May 19, 2009: [[media:PQB_Meeting_Ay_19May09.pdf]] [[media:PQB_Meeting_Ay_19May09.pptx]]
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* Accelerator PQB Meeting April 28, 2009: [[media:PQB_Meeting_rtfeedback_28April09.pdf]] [[media:PQB_Meeting_rtfeedback_28April09.pptx]]
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* Accelerator PQB Meeting April 7, 2009: [[media:PQB_Meeting_07April09.pdf]] [[media:PQB_Meeting_07April09.pptx]]
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* Accelerator PQB Meeting March 24, 2009: [[media:PQB_Meeting_24March09.pdf]] [[media:PQB_Meeting_24March09.pptx]]
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* Accelerator PQB Meeting March 5, 2009: [[media:PQB_Meeting_05March09.pdf]] [[media:PQB_Meeting_05March09.pptx]]
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* Accelerator PQB Meeting February 17, 2009: [[media:PQB_Meeting_17Feb09.pdf]] [[media:PQB_Meeting_17Feb09.pptx]]
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* Accelerator PQB Meeting November 10, 2008: [[media:PQB_Meeting_10Nov08.pdf]] [[media:PQB_Meeting_10Nov08.pptx]]
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* Accelerator PQB Meeting September 1, 2008: [[media:PQB_Meeting_01Sep08.pdf]] [[media:PQB_Meeting_01Sep08.pptx]]
 +
 
 +
=='''B-Team Presentations'''==
 +
 
 +
* B-Team PQB Presentation October 28, 2009: [[media:B-Team_PQB_28Oct09.pdf]] [[media:B-Team_PQB_28Oct09.ppt]]
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* B-Team PQB Presentation May 13, 2009: [[media:B-Team_PSSNoise_13May09.pdf]] [[media:B-Team_PSSNoise_13May09.ppt]]
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* B-Team PQB Presentation April 29, 2009: [[media:B-Team_PQB_29April09.pdf]] [[media:B-Team_PQB_29April09.ppt]]
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* B-Team PQB Presentation December 3, 2008: [[media:B-Team_PQB_03Dec08.pdf]] [[media:B-Team_PQB_03Dec08.ppt]]
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* B-Team PQB Presentation October 9, 2008: [[media:B-Team_PQB_09Oct08.pdf]] [[media:B-Team_PQB_09Oct08.ppt]]
 +
 
 +
=='''Collaboration Presentations'''==
 +
 
 +
* QWeak Collaboration Meeting September 17, 2010: [[media:QWeak_Coll_17Sep10.pdf]] [[media:QWeak_Coll_17Sep10.pptx]]
 +
* QWeak Collaboration Meeting May 24, 2010: [[media:QWeak_Coll_24May10.pdf]] [[media:QWeak_Coll_24May10.pptx]]
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* QWeak Collaboration Meeting February 1, 2010: [[media:QWeak_Coll_01Feb10.pdf]] [[media:QWeak_Coll_01Feb10.pptx]]
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* QWeak Collaboration Meeting February 1, 2010: [[media:QWeakInjTeam_01Feb10.pdf]] [[media:QWeakInjTeam_01Feb10.pptx]]
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* QWeak Collaboration Meeting November 8, 2009: [[media:QWeak_Coll_08Nov09.pdf]] [[media:QWeak_Coll_08Nov09.pptx]]
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* QWeak Collaboration Meeting November 8, 2009: [[media:QWeakInjTeam_08Nov09.pdf]] [[media:QWeakInjTeam_08Nov09.pptx]]
 +
* QWeak Collaboration Meeting July 17, 2009: [[media:QWeak_Coll_17Jul09.pdf]] [[media:QWeak_Col_17Jul09.pptx]]
 +
* QWeak Collaboration Meeting November 18, 2008: [[media:QWeak_Coll_18Nov08.pdf]] [[media:QWeak_Coll_18Nov08.pptx]]
 +
 
 +
=='''Other Presentations'''==
 +
 
 +
* CEBAF Ops Parity Training (August 5, 2009): [[media:parity_Ops_Training_05Aug09.pdf]] [[media:parity_Ops_Training_05Aug09.pptx]]
 +
* S&T Review (July 14, 2009): [[media:S&T_Review_2009.pdf]] [[media:S&T_Review_2009.pptx]]
 +
* PAVI09 (June 22, 2009): [[media:PAVI09_suleiman.pdf]] [[media:PAVI09_suleiman.ppt]]
 +
 
 +
=='''Technical Developments'''==
 +
 
 +
* QWeak Beam Requirements: [[media:Qweak.Beam.Requirements.pdf]]
 +
 
 +
* Discussion of technical developments in preparation for the QWeak experiment:
 +
 
 +
''Jefferson Lab injector development for next generation parity violation experiments''.
 +
J. Grames, J. Hansknect, M. Poelker, R. Suleiman, Hyperfine Interactions '''201''' (2011) 69 [[media:HyperfineInter.201.69.pdf]]
 +
 
 +
 
 +
* Schematic of Jefferson Lab Injector setup: [[media:jlab_source_PV3.pdf]] [[media:jlab_source_PV3.pptx]]
 +
 
 +
[[file:jlab_source_PV3.png|center|800px|]]
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 +
 
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==='''Two-Wien Slow Helicity Reversal'''===
 +
 
 +
* ''Two Wien Filter Spin Flipper''. J. Grames et al., Part. Accel. Conference (PAC’11), New York, NY, (2011) [[media:tup025.pdf]]
 +
 
 +
 
 +
 
 +
==='''New Helicity Board'''===
 +
 
 +
* A new helicity board was built for the QWeak experiment: [[media:NewHelBoardDesign.pdf]] [[media:NewHelBoardDesign.pptx]]
 +
 
 +
* More details can be found in the User's Guide: [[media:Helicity_Board_UserGuide.pdf]] [[media:Helicity_Board_UserGuide.docx]]
 +
 
 +
* Helicity Board Configuration Quick Reference:
 +
{| class="wikitable"
 +
|-
 +
| ''' '''
 +
| '''Mode'''
 +
| '''T_Settle'''
 +
| '''T_Stable'''
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| '''Helicity Pattern'''
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| '''Reporting Delay'''
 +
| '''Helicity Board Frequency (Hz)'''
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|-
 +
| '''Default (30 Hz)'''
 +
| Free Clock
 +
| 500 µs
 +
| 33330 µs
 +
| Quartet
 +
| 8 windows
 +
| 29.56
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|-
 +
| '''5 MeV Mott'''
 +
| Free Clock
 +
| 500 µs
 +
| 33330 µs
 +
| Quartet
 +
| No delay
 +
| 29.56
 +
|-
 +
| '''Hall A Moller'''
 +
| Free Clock
 +
| 100 µs
 +
| 16667 µs
 +
| Quartet
 +
| 8 windows
 +
| 60.0
 +
|-
 +
| '''Hall A Moller'''
 +
| Free Clock
 +
| 100 µs
 +
| 8233.35 µs
 +
| Quartet
 +
| 8 windows
 +
| 120.0
 +
|-
 +
| '''PREx'''
 +
| Free Clock
 +
| 100 µs
 +
| 4066.65 µs
 +
| Octet
 +
| 16 windows
 +
| 240.0
 +
|-
 +
| '''QWeak'''
 +
| Free Clock
 +
| 70 µs
 +
| 971.65 µs
 +
| Quartet
 +
| 8 windows
 +
| 960.0
 +
|}
 +
 
 +
* The pseudo-random 30-bit Shift Register
 +
# '''''root''''' macro is shown here (change .txt to .C): [[media:NewPseudoRanBitGenR.txt]] [[media:NewPseudoRanBitGenR.gif]]
 +
# QWeak c-code:
 +
[[file:c-code.Randbit30.jpg|center|500px|]]
 +
 
 +
 
 +
 
 +
==='''New Pockels Cell HV Switch'''===
 +
 
 +
* A simple and inexpensive high voltage switch for driving Pockels cells and other low capacitance loads: [[media:Pockelsswitchposter.pdf]] [[media:Pockelsswitchposter.pptx]]
 +
 
 +
* '''''root''''' macro to illustrate charge feedback (change .txt to .C): [[media:fback.txt]] [[media:fback.gif]] [[media:fbackave.gif]]
 +
 
 +
 
 +
 
 +
==='''Electronic Cross-talk & Ground Loop Elimination'''===
 +
 
 +
* Electronic Cross-talk & Ground Loop Elimination in Injector: [[media:jlab_source_GroundLoop.pdf]] [[media:jlab_source_GroundLoop.pptx]]
 +
 
 +
==='''Helicity Magnets Control Upgrade'''===
 +
 
 +
* On January 4, 2012, the power supply cards were modified to reduce the slopes during QWeak. Added 220 milli-ohm resistor in parallel with each channel of magnet and series load resistors (approx 3.8 ohms). Current through a given magnet should now be 2.5 - 3% of the total amplifier output current.
 +
* Details of the plan to upgrade the controls of the Helicity Magnets (to be completed before Moller experiment): [[media:HMUpgrade_plan_27Dec11.pdf]] [[media:HMUpgrade_plan_27Dec11.pptx]]
 +
 
 +
-----
 +
-----
 +
='''G0 PQB'''=
 +
 
 +
* ''The G0 experiment: Apparatus for parity-violating electron scattering measurements at forward and backward angles''.
 +
D. Androić et al., Nucl. Instr. and Meth. A '''646''' (2011) 59 [http://dx.doi.org/10.1016/j.nima.2011.04.031] [[media:NuclInstrumMethA.646.59.pdf]]
 +
 
 +
 
 +
=='''Lessons Learned'''==
 +
Lessons learned for parity violation experiments at Jefferson Laboratory is an on-going series of meetings between scientists and students from the accelerator and physics division to learn from past experiences and meet new challenges in the field of parity violation experiments:
 +
 
 +
 
 +
* Supperlattice SVT4722#2 in Gun3, January 2005:
 +
 
 +
# G0 beam studies summary to the MCC 8 AM meeting on February 1, 2005: [[media:svt4722-2_8am_050201.ppt]]
 +
 
 +
 
 +
* Parity Beam Quality Specifications:
 +
 
 +
# Specifications for Beam Parameters for HAPPEX-II and HAPPEX-He from the HAPPEX Collaboration: [[media:HAPPEX_Beam_Requirements.ps]]
 +
# Beam Parameter Specifications for the G0 Experiment from the G0 Collaboration: [[media:g0_beamspec.ps]]
 +
# Preliminary Beam Specification Parameters for the Qweak Experiment from Roger Carlini: [[media:Qweak_Beam_Parameters_Prem.pdf]] [[media:Qweak_Beam_Parameters_Prem.doc]]
 +
 
 +
 
 +
* Lessons Learned Part 1 November 18, 2004 - Meeting minutes are here: [[media:LessonsLearned_18Nov2004.pdf]] [[media:LessonsLearned_18Nov2004.docx]]
 +
 
 +
# Phase Trombone for HAPPEX-2 from Alex: [[media:Phase_Tromb_HAPPEX_2004.pdf]]
 +
# Parity Lessons Learned from Chao: [[media:Parity_Lessons_Learned_chao_2004.pdf]]
 +
# Parity Quality Beam Development and Experiment Timeline from Matt: [[media:Parity_Exp_Timeline_Poelker_2004.doc]]
 +
# Aligning the Pockels cell - the HAPPEX procedure: [[media:Aligning_the_pockels_cell_2004.doc]]
 +
# Comments about Helicity Effects for G0 and HAPPEX from Mark: [[media:pitt_parity_lessons_learned_meeting_2004.pdf]] [[media:pitt_parity_lessons_learned_meeting_2004.ppt]]
 +
# Injector Setup for G0 and HAPPEX from Reza: [[media:lessons_learned_G0_and_HAPPEx_reza_2004.ppt]]
 +
 
 +
 
 +
* Lessons Learned Part 2 December 9, 2004 - Meeting minutes are here: [[media:LessonsLearned_9Dec04.doc]]
 +
 
 +
# G0 slide regarding beam loading from Kaz: [[media:beam_loading_kaz_2004.pdf]] [[media:beam_loading_kaz_2004.ppt]]
 +
# Augmented version of slides from Mark for Part 1 meeting: [[media:pitt_parity_lessons_learned_meeting_dec_09_04.pdf]] [[media:pitt_parity_lessons_learned_meeting_dec_09_04.ppt]]
 +
# HAPPEX presentation from Kent: [[media:HAPPEX_LessonsLearned_kent_2004.pdf]] [[media:HAPPEX_LessonsLearned_kent_2004.ppt]]
 +
# Here is Chao's report on recent beam studies: [[media:Parity_meeting_120904_chao.pdf]]
 +
 
 +
 
 +
* Lessons Learned Part 3 January 13, 2005:
 +
 
 +
# Matt's meeting outline: [[media:Parity_Tests 1_05_matt.doc]]
 +
# Chao showed injector matching results from December: [[media:Test_Result_122004_chao.pdf]]
 +
# Riad's summary of Injector Studies Using Superlattice Photocathode, January 13, 2005: [[media:inj_studies_011005_riad.ppt]]
 +
 
 +
 
 +
 
 +
=='''G0 Backward Angle Run 2006'''==
 +
 
 +
* G0 Accelerator Planning Meeting, November 1, 2005:
 +
# Introduction & Proposed Beam Specifications, Grames: [[media:G0Planning_051101_grames.ppt]]
 +
# Beam Halo Considerations (from Beam Specs document), Pitt: [[media:beam_halo_pitt_051101.ppt]]
 +
# Beam Halo Forward Angle Example, Pitt: [[media:g0_halo_profile_pitt_051101.pdf]]
 +
# Proposed Accelerator Configuration, Freyberger: [[media:G0_prep_freyberger_051101.pdf]]
 +
# Source & Beam Issues, Suleiman: [[media:G0_acc_suleiman_051101.ppt]]
 +
# Injector Matching, Chao: [[media:G0_Preparation_chao_051101.pdf]]
 +
# Engineering Issues, Lauze: [[media:EEConcerns_lauze_051101.doc]]
 +
 
 +
* Beam Parameter Specifications for G0 Backward Angle Run October 7, 2005: [[media:g0_beamspec_back_angle.pdf]]
 +
 
 +
 
 +
* Summary of G0 Pockels Cell Studies:
 +
# Presentation in January 2006: [[media:pc_install_beam_studies_jan_2006.pdf]] [[media:pc_install_beam_studies_jan_2006.ppt]]
 +
# Presentation in March 2006: [[media:pc_install_beam_studies_march_2006.pdf]] [[media:pc_install_beam_studies_march_2006.ppt]]
 +
# Presentation in July 2006: [[media:pc_install_beam_studies_july_2006.pdf]] [[media:pc_install_beam_studies_july_2006.ppt]]
 +
# Presentation in September 2006: [[media:pc_install_beam_studies_sept_2006.pdf]] [[media:pc_install_beam_studies_sept_2006.ppt]]
 +
# Presentation in January 2007: [[media:pc_install_beam_studies_jan_2007.pdf]] [[media:pc_install_beam_studies_jan_2007.ppt]]
 +
 
 +
 
 +
 
 +
-----
 +
-----
 +
='''Other Presentations and Tech Notes'''=
 +
 
 +
* PREx Beam Requirements: [[media:PREx.Beam.Requirements.pdf]]
 +
* FAQ for Injector Matching. Yu-Chiu Chao, 2008: [[media:JLabTechNote.08-040.pdf]]
 +
* Collection of Notes Related to Future Work on Parity Quality Beam. Yu-Chiu Chao, 2008: [[media:JLabTechNote.08-039.pdf]]
 +
* Phase Trombone for Parity Experiments. Alex Bogacz, 2007: [[media:JLabTechNote.07-039.pdf]]
 +
* HAPPEx III Beam Requirements: [[media:HAPPEx.III.Beam.Requirements.pdf]]
 +
* HAPPEx Collaboration Meeting May 18, 2007: [[media:happex_may_2007.pdf]] [[media:happex_may_2007.ppt]]
 +
* Helicity Magnets Commissioning, MCC Talk, February 7, 2007: [[media:HelMag_Comm_MCC_talk_07Feb07.pdf]] [[media:HelMag_Comm_MCC_talk_07Feb07.pptx]]
 +
* ''The G0 Experiment: Backangle Running''. Jefferson Lab Accelerator Seimnar, Riad Suleiman, Virginia Tech, November 2, 2006: [[media:G0_Acc_Seminar_suleiman_02Nov06.pdf]]
 +
* G0 Adiabatic Damping, Marck Pitt: [[media:G0_AdiabaticDamping_pitt.pdf]] [[media:G0_AdiabaticDamping_pitt.pptx]]
 +
* Parity Violation Experiments at CEBAF Beam Specifications, Matt Poelker, March 4, 2004: [[media:parity_table_2004.ppt]]
 +
* Target Density Fluctuations and Bulk Boiling in the Hall A Cryotarget. D.S. Armstrong, B. Moffit, and R. Suleiman: [[media:JLabTechNote.03-017.pdf]]
 +
* G0 Collaboration Meeting August 16, 2002: [[media:g0_collab_aug16_2002.pdf]]
 +
 
 +
 
 +
-----
 +
-----

Latest revision as of 06:08, 3 November 2023



PQB reflection.jpg

A significant portion of the experiments performed at Jefferson Lab require a polarized electron beam. A subset of these are parity violation experiments which have exceptionally stringent requirements on the quality of the electron beam. As the sign of the electron beam helicity reverses at the target of the experiment no other measurable quantity of the electron beam may change. This includes the beam intensity, polarization, position, angle, energy or spot size.

To ensure this beam quality, a significant effort occurs at the polarized electron source, where the laser beam and electron photogun combine to produce the intended electron beam. Also significant is the ability to accelerate the beam to high energy while transporting it to the experimental target, all while maintaining a parity quality electron beam (PQB).



Parity Violation

Discussion of parity violation can be found at NIST: The Fall of Parity: [1]



Accelerator Setup to Run Parity Violation

An overview of how parity-violating electron scattering experiments are performed at CEBAF, P.A. Adderley et al., Nuclear Inst. and Methods in Physics Research, A 1046 (2023) 167710. [2]



Parity Violation Experiments

  1. JLab Hall A Parity Experiments (HAPPEx, PREx, C-REx, PVDIS): [3]
  2. JLab Hall C G0 Experiment
  3. JLab Hall C QWeak Experiment: [4]
  4. JLab Hall A Møller Experiment: [5]
  5. Mainz A4 Experiment


PV Experiments Dec2022.jpg
  • Table References:
  1. Measurement of the neutral weak form factors of the proton, K. A. Aniol et al., Phys. Rev. Lett. 82, 1096 (1999). [6]
  2. New Measurement of Parity Violation in Elastic Electron-Proton Scattering and Implications for Strange Form Factors. K. A. Aniol et al., Phys. Lett. B 509, 211 (2001). [7]
  3. Parity-violating Electroweak Asymmetry in e ⃗p Scattering. K. A. Aniol et al., Phys. Rev. C 69, 065501 (2004). [8]
  4. Strange-Quark Contributions to Parity-Violating Asymmetries in the Forward G0 Electron-Proton Scattering Experiment, D. S. Armstrong et al. Phys. Rev. Lett. 95, 092001 (2005). [9]
  5. Parity-Violating Electron Scattering from 4He and the Strange Electric Form Factor of the Nucleon, K. A. Aniol et al., Phys. Rev. Lett. 96, 022003 (2006). [10]
  6. Constraints on the nucleon strange form factors at Q2 ∼ 0.1 GeV2. K. A. Aniol et al., Phys. Lett. B 635, 275 (2006). [11]
  7. Precision Measurements of the Nucleon Strange Form Factors at Q2∼0.1 GeV2 , A. Acha et al., Phys. Rev. Lett. 98, 032301 (2007). [12]
  8. Strange Quark Contributions to Parity-Violating Asymmetries in the Backward Angle G0 Electron Scattering Experiment, D. Androić et al., Phys. Rev. Lett. 104, 012001 (2010). [13]
  9. New Precision Limit on the Strange Vector Form Factors of the Proton, Z. Ahmed et al., Phys. Rev. Lett. 108, 102001 (2012). [14]
  10. Measurements of Parity-Violating Asymmetries in Electron-Deuteron Scattering in the Nucleon Resonance Region. D. Wang et al., Phys. Rev. Lett. 111, 082501 (2013). [15]
  11. Measurement of parity violation in electron-quark scattering. D. Wang et al., Nature 506, 67 (2014). [16]
  12. Measurement of parity-violating asymmetry in electron-deuteron inelastic scattering. D. Wang et al., Phys. Rev. C 91, 045506 (2015). [17]
  13. Measurement of the Neutron Radius of 208Pb through Parity Violation in Electron Scattering, S. Abrahamyan et al., Phys. Rev. Lett. 108, 112502 (2012). [18]
  14. First Determination of the Weak Charge of the Proton, D. Androic et al., Phys. Rev. Lett. 111, 141803 (2013). [19]
  15. Precision measurement of the weak charge of the proton. D. Androi´c et al., Nature 557, 207 (2018). [20]
  16. Parity-violating inelastic electron-proton scattering at low Q2 above the resonance region, D. Androić et al., Phys. Rev. C 101, 055503 (2020). [21]
  17. Determination of the 27Al Neutron Distribution Radius from a Parity-Violating Electron Scattering Measurement, D. Androić et al., Phys. Rev. Lett. 128, 132501 (2022). [22]
  18. Accurate Determination of the Neutron Skin Thickness of 208Pb through Parity-Violation in Electron Scattering, D. Adhikari et al., Phys. Rev. Lett. 126, 172502 (2021). [23]
  19. Precision Determination of the Neutral Weak Form Factor of 48Ca, D. Adhikari et al., Phys. Rev. Lett. 129, 042501 (2022). [24]
  20. The MOLLER Experiment: An Ultra-Precise Measurement of the Weak Mixing Angle Using Møller Scattering, J. Benesch et al., arXiv:1411.4088. [25]
  21. SoLID (Solenoidal Large Intensity Device), Updated Preliminary Conceptual Design Report, The SoLID Collaboration, November 2019. [26]



Selected References

  • Experimental Test of Parity Conservation in Beta Decay.

C. S. Wu et al., Phys. Rev. 105 (1957) 1413 [27] media:PhysRev.105.1413.pdf

  • Parity-Violating Electron Scattering and the Electric and Magnetic Strange Form Factors of the Nucleon.

D. S. Armstrong and R. D. McKeown, Annu. Rev. Nucl. Part. 62 (2012) 337 [28] media:annurev-nucl-102010-130419.pdf

  • The Qweak experimental apparatus.

T. Allison et al., Nucl. Instr. and Meth. A 781 (2015) 105 [29] media:NuclInstrumMethA.781.105.pdf


Injector PQB Setup

  • SLAC's polarized electron source laser system and minimization of electron beam helicity correlations for the E-158 parity violation experiment.

T. B. Humensky et al., Nucl. Instr. and Meth. A 521 (2004) 261 [30] media:NuclInstrMethA.521.261.pdf

  • Helicity correlated asymmetries caused by optical imperfections.

K. Aulenbacher, Euro. Phys. J. A 32 (2007) 543 [31] media:EuroPhysJA.32.543.pdf


Mailing List

  • Accelerator Parity Quality Beam mailing list: acc_parity@jlab.org
  • Web page for users of mailing list is: [32]


MOLLER PQB

Helicity Decoder Board

Synchrotron Radiation

Collaboration Presentations

  1. Beam Monitoring: media:Moller_23Jan15_pitt.pdf

Other Presentations

PREx-II PQB


QWeak PQB

Accelerator Meetings

B-Team Presentations

Collaboration Presentations

Other Presentations

Technical Developments

  • Discussion of technical developments in preparation for the QWeak experiment:

Jefferson Lab injector development for next generation parity violation experiments. J. Grames, J. Hansknect, M. Poelker, R. Suleiman, Hyperfine Interactions 201 (2011) 69 media:HyperfineInter.201.69.pdf


Jlab source PV3.png


Two-Wien Slow Helicity Reversal

  • Two Wien Filter Spin Flipper. J. Grames et al., Part. Accel. Conference (PAC’11), New York, NY, (2011) media:tup025.pdf


New Helicity Board

  • Helicity Board Configuration Quick Reference:
Mode T_Settle T_Stable Helicity Pattern Reporting Delay Helicity Board Frequency (Hz)
Default (30 Hz) Free Clock 500 µs 33330 µs Quartet 8 windows 29.56
5 MeV Mott Free Clock 500 µs 33330 µs Quartet No delay 29.56
Hall A Moller Free Clock 100 µs 16667 µs Quartet 8 windows 60.0
Hall A Moller Free Clock 100 µs 8233.35 µs Quartet 8 windows 120.0
PREx Free Clock 100 µs 4066.65 µs Octet 16 windows 240.0
QWeak Free Clock 70 µs 971.65 µs Quartet 8 windows 960.0
  • The pseudo-random 30-bit Shift Register
  1. root macro is shown here (change .txt to .C): media:NewPseudoRanBitGenR.txt media:NewPseudoRanBitGenR.gif
  2. QWeak c-code:
C-code.Randbit30.jpg


New Pockels Cell HV Switch


Electronic Cross-talk & Ground Loop Elimination

Helicity Magnets Control Upgrade

  • On January 4, 2012, the power supply cards were modified to reduce the slopes during QWeak. Added 220 milli-ohm resistor in parallel with each channel of magnet and series load resistors (approx 3.8 ohms). Current through a given magnet should now be 2.5 - 3% of the total amplifier output current.
  • Details of the plan to upgrade the controls of the Helicity Magnets (to be completed before Moller experiment): media:HMUpgrade_plan_27Dec11.pdf media:HMUpgrade_plan_27Dec11.pptx

G0 PQB

  • The G0 experiment: Apparatus for parity-violating electron scattering measurements at forward and backward angles.

D. Androić et al., Nucl. Instr. and Meth. A 646 (2011) 59 [36] media:NuclInstrumMethA.646.59.pdf


Lessons Learned

Lessons learned for parity violation experiments at Jefferson Laboratory is an on-going series of meetings between scientists and students from the accelerator and physics division to learn from past experiences and meet new challenges in the field of parity violation experiments:


  • Supperlattice SVT4722#2 in Gun3, January 2005:
  1. G0 beam studies summary to the MCC 8 AM meeting on February 1, 2005: media:svt4722-2_8am_050201.ppt


  • Parity Beam Quality Specifications:
  1. Specifications for Beam Parameters for HAPPEX-II and HAPPEX-He from the HAPPEX Collaboration: media:HAPPEX_Beam_Requirements.ps
  2. Beam Parameter Specifications for the G0 Experiment from the G0 Collaboration: media:g0_beamspec.ps
  3. Preliminary Beam Specification Parameters for the Qweak Experiment from Roger Carlini: media:Qweak_Beam_Parameters_Prem.pdf media:Qweak_Beam_Parameters_Prem.doc


  1. Phase Trombone for HAPPEX-2 from Alex: media:Phase_Tromb_HAPPEX_2004.pdf
  2. Parity Lessons Learned from Chao: media:Parity_Lessons_Learned_chao_2004.pdf
  3. Parity Quality Beam Development and Experiment Timeline from Matt: media:Parity_Exp_Timeline_Poelker_2004.doc
  4. Aligning the Pockels cell - the HAPPEX procedure: media:Aligning_the_pockels_cell_2004.doc
  5. Comments about Helicity Effects for G0 and HAPPEX from Mark: media:pitt_parity_lessons_learned_meeting_2004.pdf media:pitt_parity_lessons_learned_meeting_2004.ppt
  6. Injector Setup for G0 and HAPPEX from Reza: media:lessons_learned_G0_and_HAPPEx_reza_2004.ppt


  1. G0 slide regarding beam loading from Kaz: media:beam_loading_kaz_2004.pdf media:beam_loading_kaz_2004.ppt
  2. Augmented version of slides from Mark for Part 1 meeting: media:pitt_parity_lessons_learned_meeting_dec_09_04.pdf media:pitt_parity_lessons_learned_meeting_dec_09_04.ppt
  3. HAPPEX presentation from Kent: media:HAPPEX_LessonsLearned_kent_2004.pdf media:HAPPEX_LessonsLearned_kent_2004.ppt
  4. Here is Chao's report on recent beam studies: media:Parity_meeting_120904_chao.pdf


  • Lessons Learned Part 3 January 13, 2005:
  1. Matt's meeting outline: media:Parity_Tests 1_05_matt.doc
  2. Chao showed injector matching results from December: media:Test_Result_122004_chao.pdf
  3. Riad's summary of Injector Studies Using Superlattice Photocathode, January 13, 2005: media:inj_studies_011005_riad.ppt


G0 Backward Angle Run 2006

  • G0 Accelerator Planning Meeting, November 1, 2005:
  1. Introduction & Proposed Beam Specifications, Grames: media:G0Planning_051101_grames.ppt
  2. Beam Halo Considerations (from Beam Specs document), Pitt: media:beam_halo_pitt_051101.ppt
  3. Beam Halo Forward Angle Example, Pitt: media:g0_halo_profile_pitt_051101.pdf
  4. Proposed Accelerator Configuration, Freyberger: media:G0_prep_freyberger_051101.pdf
  5. Source & Beam Issues, Suleiman: media:G0_acc_suleiman_051101.ppt
  6. Injector Matching, Chao: media:G0_Preparation_chao_051101.pdf
  7. Engineering Issues, Lauze: media:EEConcerns_lauze_051101.doc


  • Summary of G0 Pockels Cell Studies:
  1. Presentation in January 2006: media:pc_install_beam_studies_jan_2006.pdf media:pc_install_beam_studies_jan_2006.ppt
  2. Presentation in March 2006: media:pc_install_beam_studies_march_2006.pdf media:pc_install_beam_studies_march_2006.ppt
  3. Presentation in July 2006: media:pc_install_beam_studies_july_2006.pdf media:pc_install_beam_studies_july_2006.ppt
  4. Presentation in September 2006: media:pc_install_beam_studies_sept_2006.pdf media:pc_install_beam_studies_sept_2006.ppt
  5. Presentation in January 2007: media:pc_install_beam_studies_jan_2007.pdf media:pc_install_beam_studies_jan_2007.ppt


Other Presentations and Tech Notes


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