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Title: The Search for Low Energy Single Photons in MicroBooNE

Thesis/Dissertation ·
DOI:https://doi.org/10.2172/1498547· OSTI ID:1498547

The MiniBooNE experiment is a Cherenkov based experiment located on the Booster Neutrino Beam. It observed an unexplained excess of $$\nu_e$$ charged current quasi-elastic (CCQE) event candidates in the reconstructed $$E_{\nu}^{QE}\approx 200-475$$ MeV region known as the ``Low Energy Excess'' (LEE). These $$\nu_e$$ CCQE event candidates were in the form of lone showers, a signature left by both electrons and photons indistinguishably in the MiniBooNE detector. For this reason the identity of the MiniBooNE LEE as a photon or electron excess is currently unknown. Liquid argon time projection chambers (LArTPCs) are a relatively new type of detector able to distinguish between photons and electrons. The MicroBooNE detector is one such LArTPC and is situated on the same beamline and at a similar baseline as the MiniBooNE detector. This makes MicroBooNE an ideal experiment to test the photon and electron interpretations of the MiniBooNE LEE. This thesis presents the search for a photon LEE using an enhanced rate of neutrino-induced neutral current (NC) $$\Delta$$ production and subsequent radiative decay (NC $$\Delta$$ radiative) as the candidate source. A multi-stage NC $$\Delta$$ radiative event selection has been developed which takes full advantage of MicroBooNE's photon-electron discrimination capability. The ability of the search to select NC $$\Delta$$ radiative events in MicroBooNE and validation of the search with 4.8$$\times 10^{19}$$ protons-on-target worth of data are presented. Also shown are preliminary studies of MicroBooNE's sensitivity to a NC $$\Delta$$ radiative interpretation of the LEE.

Research Organization:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), High Energy Physics (HEP)
DOE Contract Number:
AC02-07CH11359
OSTI ID:
1498547
Report Number(s):
FERMILAB-THESIS-2018-28; 1724196
Country of Publication:
United States
Language:
English