An Accelerator-Produced, Sub-GeV Dark Matter Search with the MiniBooNE Neutrino Detector Robert Cooper, New Mexico State University on behalf of the MiniBooNE Collaboration

Dark Matter Overview Abundance of cosmological and indirect evidence for dark matter Galaxy radial velocity Gravitational lensing Nebulae dynamics “Wimp Miracle” suggests 1-1000 GeV dark matter scale So far, no fully verified detection claims Direct (Colliders) Annhilation Scattering 10/31/15 R.L. Cooper -- APS DNP 2015

Minimal Vector Portal Model Similar to “dark photon” and introduces additional dark sector coupled kinematically with U(1) vector mediator: 4 new parameters: Need to suppress SM decays: mV > 2mc SM Detection Production 1C. Boehm & P. Fayet, Nucl. Phys. B683 (2004) 219. arXiv:hep-ph/0305261 [hep-ph] C. Boehm et al., Phys. Rev. Lett. 92 (2004) 101301. arXiv:astro-ph/0309686 [astro-ph] B. Batell et al., Phys. Rev. Lett. 113 (2014) 171802. arXiv:1406.2698 [hep-ph] P. deNiverville et al., Phys. Rev. D84 (2011) 075020. arXiv:1107.4580 [hep-ph] 10/31/15 R.L. Cooper -- APS DNP 2015

The MiniBooNE Detector 12 m, 800 ton mineral oil (CH2) Cherenkov detector for nm  ne oscillation search Optically separated Inner signal / outer veto regions (1280 / 240) × 8” PMTs Nucleon / electron PID from slower impurity fluor scintillation (N) vs. Cherenkov (e/m) 10 years running: n-mode (6.7×1020 POT), n-mode (11.5×1020 POT) 11 oscillation, 14 cross section / flux papers 19 Ph.D Theses 1A.A. Aguilar-Arevalo et al., Nucl. Instrum. Meth. A599 (2009) 28. arXiv:0806.4201 [hep-ex] 2See our website for a list of all publications. http://www-boone.fnal.gov/ 10/31/15 R.L. Cooper -- APS DNP 2015

Suppress n and Produce c at BNB Normal operation: FNAL BNB delivers 8.9 GeV protons Be target  typical 2×1020 POT yearly Dark matter operation: divert beam “around” target to 50 m steel beamstop p± DIF (nm progenitor) suppressed by absorption or DAR in beamstop p0 decays quickly (c progenitor) and unaffected by beamstop Beam “off-target” to 50 m beamstop 10/31/15 R.L. Cooper -- APS DNP 2015

Off-Target Neutrino Background New Beamline MC developed CCQE finds ~50 suppression factor Preliminary Preliminary ON  OFF Target MC 1A.A. Aguilar-Arevalo et al., Phys. Rev. D79 (2009) 072002. arXiv:0806.1449 [hep-ex] 10/31/15 R.L. Cooper -- APS DNP 2015

MiniBooNE Neutrino Suppression 10 months of running and we collected 1.86×1020 POT 10/31/15 R.L. Cooper -- APS DNP 2015

What Is Expected In MiniBooNE? Consider nucleon elastic scattering 35-250 MeV most sensitive recoil range Same as n NC elastic  SUPPRESS n DM signal + n BG With production, cross section, and efficiency: most sensitive region is 35-250 MeV nucleons n BG 1A.A. Aguilar-Arevalo et al., Phys. Rev. D82 (2010) 092005. arXiv:1007.4730 [hep-ex] 2A.A. Aguilar-Arevalo et al., Phys. Rev. D91 (2014) 012004. arXiv:1309.7257 [hep-ex] 10/31/15 R.L. Cooper -- APS DNP 2015

Preliminary Results (3.19×1019 POT) Event Selection: 1 Track (1 recoil) In beam time Fiducialized No veto activity Hits threshold Energy threshold Nucleon PID Blind Analysis (17% of data open) Anticipate systematics limited at about 10% Beam unrelated is largest in total c n,p 10/31/15 R.L. Cooper -- APS DNP 2015

Double Ratio Method Preliminary Preliminary Preliminary Preliminary Many systematics in common On-target n runs Off-target c runs Neutral current (NC) Charged current (CC) Initial estimates assume uncorrelated errors Shown are individual distributions Final fit on ratio soon Preliminary Preliminary Preliminary Preliminary 10/31/15 R.L. Cooper -- APS DNP 2015

Dark Matter Propagation Time Massive c delayed relative n (mc = 120 MeV, E = 1.5 GeV  6 ns ) Beam – 81× 20 ns RF bunches dt ~ 1.5 ns Cherenkov (ec) dt ~ 4.2 ns Scintillation (Nc) Preliminary Preliminary 10/31/15 R.L. Cooper -- APS DNP 2015

Dark Matter Exclusion Plots Nucleon – DM Electron – DM 100-1000 events 10-100 events 1-10 events 10/31/15 R.L. Cooper -- APS DNP 2015

Conclusions MiniBooNE has collected 1.86×1020 POT in beam-off-target configuration to search for sub-GeV dark matter Beam-off-target suppresses neutrino backgrounds  beam uncorrelated backgrounds dominant First of its kind, proton beam dump to a large neutrino detector  an extremely well characterized detector! N-DM analysis will be completed soon  e-DM and inelastic p0 channels are underway 10/31/15 R.L. Cooper -- APS DNP 2015

Previous Beam Dump / Fixed Target Experiments – Proton Beams 1Table by R.T. Thornton, Indiana University Nuclear Physics Seminar, Nov. 21, 2014 10/31/15 R.L. Cooper -- APS DNP 2015

Vector Portal Exclusion Plots Nucleon – DM Electron – DM 100-1000 events 10-100 events 1-10 events 10/31/15 R.L. Cooper -- APS DNP 2015

Decay Pipe Survey with FRED FRED: Finding Radiation Evidence in the Decay pipe Visual and magnetic field survey  no anomalies Deployable mast for Hall probes 1 & 2 Hall probe 1 Hall probe 2 Forward-looking LIDAR Hall probe 3 Camera & Light & Mic Rear-looking LIDAR Water level Gyro Accelerometer LabJack digitizer PoE / USB power distribution system Tether & strain relief Flipper arm 10/31/15 R.L. Cooper -- APS DNP 2015