Search for Light Dark Matter Produced in a Proton Beam Dump

Abstract

This work would not have been completed without the help and support of several people. My wife, Holly, has been supportive throughout the entire process, while my children, David and Samuel, have been a huge motivation, always ready to entertain me during much needed breaks. The teaching and encouragement I received while under the leadership of my professors at Abilene Christian University formed the bedrock of my success in graduate school. Thank you. I am thankful Rex Tayloe took a chance on me: helped me get into Indiana University, was willing to be my advisor, and allowed my work schedule to be flexible once my children were born. Rex, Robert Cooper, and Lance Garrison helped me get my feet wet at IU and tought me how to work in/with a small collaboration. Rex, Robert, and Richard Van de Water encouraged me to make this analysis my own, not adhearing to what others had invision the analysis would be. I am thankful for their guidence and many productive conversations. I am thankful for Ranjan Dharmapalan's hard work in getting this analysis started, as an extension to his thesis, and helping me get up to speed. Much apparition goes out to Zarko Pavlovic in his continue work on the MiniBooNE computers. None of the current MiniBooNE analyses can be done without his hard work. This analysis is an accumulation of over a decade of work by a large number of people: the MiniBooNE collaboration, Fermilab Accelerator Division, and the neutrino group at Los Alamos to name a few. Their work in building/understanding the Booster Neutrino Beamline and MiniBooNE detector for the oscillation and cross section analyses allowed this analysis to be completed. I am thankful for collaborators like Byron Roe, Bill Louis, and Mike Shaevitz who still contribute and phone-in to detailed analyses meetings. This work could not have been completed with out the efforts of Patrick deNiverville iv and Brian Batell. I am so thankful for their work in developing the dark matter generator and being willing to answer my questions. v Remington Tyler Thornton SEARCH FOR LIGHT DARK MATTER PRODUCED IN A PROTON BEAM DUMP Cosmological observations indicate that our universe contains dark matter (DM), yet we have no measurements of its microscopic properties. Whereas the gravitational interaction of DM is well understood, its interaction with the Standard Model is not. Direct detection experiments, the current standard, search for a nuclear recoil interaction and have a low-mass sensitivity edge of order 1 GeV. A path to detect DM with mass below 1 GeV is the use of accelerators producing boosted low-mass DM. Using neutrino detectors to search for low-mass DM is logical due to the similarity of the DM and neutrino signatures in the detector. The MiniBooNE experiment, located at Fermilab on the Booster Neutrino Beamline, has produced the first proton beam-dump light DM search results. Using dark matter scattering from nucleons 90% confidence limits were set over a large parameter space and, to allow tests of other theories, a model independent DM r...

First constraint on coherent elastic neutrino-nucleus scattering in argon

“…The likelihood fit was performed by passing a total of 4663 events surviving the likelihood cuts to a 3D likelihood function in energy, time, and F prompt space including beamunrelated and beam-related neutron backgrounds along with a CEvNS signal. A profile likelihood curve was calculated as a function of the number of CEvNS events and a frequentist confidence limit (CL) method [45][46][47], along with a simple treatment of the large systematic errors, was used to place on upper limit on the number of CEvNS events of < 7.4 events. This result can be used to place a 68% CL on the stopped-pion flux-averaged cross section of <3.4 × 10 −39 cm 2 , within twice the SM prediction of 1.8 × 10 −39 cm 2 [48].…”

Dark matter search in nucleon, pion, and electron channels from a proton beam dump with MiniBooNE

“…The cut is set to reject all events that have a trigger of greater than or equal to 60 hits in the detector within 10 µs before the event trigger. The efficiency of NCE7 for beam-related events that passed the previous cuts is (95.3 ± 0.2) %, while beam-unrelated backgrounds are reduced by 42.5% [41]. NCE selection cuts are 30% efficient at detecting true NCE, NCπ 0 and neutral-current single charged pion (NCπ ± ) events with an energy transfer greater than or equal to 90 MeV and that interact in the fiducial volume.…”

“…A simulation study was able to account for the increased rate by moving the primary beam angles within 2σ of their uncertainties [41]. These small movements caused the tails of the beam to scrape the beryllium target downstream of the 90 • beam-loss monitor.…”

“…Comparing CCQE data in off-target mode to three different Monte Carlo predictions for neutrinos interacting in the detector (ν det ). The dotted line is the output of the nominal off-target beam profile, the dashed line is the nominal profile scale by 1.6, and the solid line is the average of the scrapings (Average CV) used as the final Φ Off[41]. E QE ν is defined by Eq.…”