A' Experiment (APEX): PR-10-009, E12-10-009

Summary

The A' Experiment (APEX) will search for a new vector boson A' with very weak coupling to electrons in the mass range from 65 MeV to 550 MeV. New vector bosons with such small couplings arise naturally from a small kinetic mixing of the "dark photon" A' with the photon -- one of the very few ways in which new forces can couple to the Standard Model -- and have received considerable attention as an explanation of various dark matter related anomalies. A' bosons are produced by radiation off an electron beam, and could appear as narrow resonances with small production cross-section in the QED e+e- spectrum.

Proposals and Review

• Proposal and presentation to PAC 37 (PDF)
• Presentation to Hall A Collaboration, December 16 2013
• PAC37 report on APEX (full report here)
• Proposal to PAC35 (PDF)
• Presentation to Hall A in 2009 (PDF)
• Presentation to PAC35 (PDF)
• Reply to TAC comments (1 and 2)

APEX Test Run Result, Theses, and Selected Talks

• PRL based on 2010 APEX test run: "Search for a New Gauge Boson in Electron-Nucleus Fixed-Target Scattering by the APEX Experiment", APEX Collaboration (Abrahamyan et al.). 10.1103/PhysRevLett.107.191804 (70+ citations on INSPIRE)
• APEX contributions to Hall A Annual Report in 2010 and 2011 on Test Run and analysis
• Eric Jensen (College of William and Mary) PhD Thesis on APEX Test Run
• Previous APEX Talks:
• MENU 2013 (James Beacham, Oct 3, 2013)
• Snowmass Intensity Frontier Workshop (Philip Schuster, April 26 2013)
• Talk for Heavy Photon Search Collaboration (Natalia Toro, June 4 2013)
• Recent APEX Talks:
• Joint Halls A/C Summer Meeting 2020 (John Williamson, July 16, 2020)
• 2020 Fall Meeting of the APS Division of Nuclear Physics (Sean Jeffas, Oct 30th, 2020)

Past Collaboration Meetings

• Spring 2015
• Spring 2014

Physics References

• Review Articles and Talks

• "Dark Sectors and New, Light, Weakly-Coupled Particles", Essig et al. arXiv:1311.0029. Report of the Community Summer Study 2013 (Snowmass) Intensity Frontier New, Light, Weakly-Coupled Particles subgroup
• "Fundamental Physics at the Intensity Frontier", Hewett et al. arXiv:1205.2671 Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. (Section 6: New, Light, Weakly-Coupled Particles). See also working group website.
• "Dark Forces, Dark Matter, and the GeV-Scale Discovery Frontier". Philip Schuster at APS DNP (October 2013)

• Workshops on New GeV-Scale Forces

• Snowmass 2013: Intensity Frontier Workshop (group IF5) and Snowmass On the Mississippi (Wednesday and Thursday parallel sessions and Colloquia)
• Dark 2012 (Frascati, Oct 2012)
• Searching for a New Gauge Boson at Jefferson Lab (September 2010)
• Dark Forces Workshop (SLAC, 2009)

• Theory

• New Forces and Fixed Target Searches
• "Two U(1)'s and Epsilon Charge Shifts" - Holdom Phys.Lett. B166 (1986)
• "New Fixed-Target Experiments to Search for Dark Gauge Forces", Bjorken, Essig, Schuster, Toro. Phys.Rev.D80:075018,20090 arXiv:0906.0580
• "Dark Force Detection in Low Energy e-p Collisions", Freytsis, Ovanesyan, Thaler. JHEP 1001:111,2010, arXiv:0909.2862
• "Searching for the light dark gauge boson in GeV-scale experiments", Reece and Wang. JHEP 0907:051,2009 arXiv:0904.1743
• "Theoretical framework to analyze searches for hidden light gauge bosons in electron scattering fixed target experiments", Beranek, Merkel, Vanderhaeghen arXiv:1303.2540
• "New Limits on Hidden Photons from Past Electron Beam Dumps", Andreas, Niebuhr, Ringwald Phys.Rev. D86 (2012) 095019, e-Print: arXiv:1209.6083
• Models
• "Abelian Hidden Sectors at a GeV", Morrissey, Poland, Zurek JHEP 0907 (2009) 050 arXiv:0904.2567
• "Kinetic Mixing as the Origin of Light Dark Scales", Cheung et al Phys.Rev. D80 (2009) 035008 arXiv:0902.3246
• "Breaking the Dark Force", Katz and Sundrum JHEP 0906 (2009) 003 arXiv:0902.3271
• " Naturally Light Hidden Photons in LARGE Volume String Compactifications", Goodsell et al JHEP 0911 (2009) 027 arXiv:0909.0515
• Dark Matter Connections
• "A Theory of Dark Matter", Arkani-Hamed et al Phys.Rev. D79 (2009) 015014 arXiv:0810.0713
• "Astrophysical Signatures of Secluded Dark Matter", Pospelov and Ritz Phys.Lett. B671 (2009) 391-397 arXiv:0810.1502
• "Asymmetric Dark Matter: Theories, Signatures, and Constraints" (review article), Kathryn M. Zurek arXiv:1308.0338
• "Sommerfeld-enhanced annihilation in dark matter substructure: Consequences for constraints on cosmic-ray excesses", Slatyer, Toro, Weiner Phys.Rev. D86 (2012) 083534 arXiv:1107.3546
• See also recent talks by Tracy Slatyer (at Snowmass IF, April 2013) and Kathryn Zurek (at SLAC, Jan 2014)

Operations (From Test Run)

• Test Run information
• Run Plan for Pilot Run (06/22/10 version)
• Shift HOW-TO
• Safety
• Run Plan for Pilot Run (06/22/10 version)
• Approval from Larry Cardman