PROSPECT Precision Oscillation and Spectrum Experiment Karsten M. - PowerPoint PPT Presentation

PROSPECT Precision Oscillation and Spectrum Experiment Karsten M. Heeger Yale University on behalf of the PROSPECT collaboration � 1

Reactor Antineutrinos ν e from β -decays, pure ν e source of n-rich fission products on average ~6 beta decays until stable mean energy of ν e : 3.6 MeV > 99.9% of ν e are produced by fissions in only disappearance 235 U, 238 U, 239 Pu, 241 Pu experiments possible Karsten Heeger, Yale University � 2 Moriond 2019

Reactor Antineutrino “Anomalies” (RAA) Flux Deficit Spectral Deviation Deficit due to extra (sterile) neutrino Measured spectrum does not agree oscillations or artifact of flux predictions? with predictions. Daya Bay, CPC 41, No. 1 (2017) Understanding reactor flux and spectrum anomalies requires additional data � 3 Karsten Heeger, Yale University Moriond 2019

Reactor Antineutrino “Anomalies” (RAA) Flux Deficit Spectral Deviation Phys. Rev. D 83, 073006 (2011) Deficit due to extra (sterile) neutrino Measured spectrum does not agree oscillations or artifact of flux predictions? with predictions. Daya Bay, CPC 41, No. 1 (2017) Understanding reactor flux and spectrum anomalies requires additional data � 4 Karsten Heeger, Yale University Moriond 2019

Precision Oscillation and Spectrum Experiment Antineutrino Shielding Detector Active Inner Detector HFIR Core Search for short-baseline oscillation at <10m Objectives Precision measurement of 235 U reactor ν e spectrum Relative Spectrum Measurement Segmented, 6 Li-loaded Detector relative measurement of L/E and spectral shape distortions oscillated spectrum unoscillated spectrum Karsten Heeger, Yale University � 5 Moriond 2019

Experimental Site High Flux Isotope Reactor, ORNL Reactor Core Power : 85 MW Core shape: cylindrical Size: h=0.5m r=0.2m Duty-cycle : 46%, 7 cycles/yr, 24 days Fuel: HEU ( 235 U) compact reactor core, detector near surface, highly-enriched (HEU): >99% of ν e flux from 235 U fission little overburden Karsten Heeger, Yale University � 6 Moriond 2019

PROSPECT Detector Design WATER BRICK NEUTRON SHIELD Single 4,000 L 6 Li-loaded liquid scintillator (3,000 L fiducial volume) BORATED POLYETHELYNE 11 x 14 (154) array of optically separated segments Very low mass separators (1.5 mm thick) INNER DETECTOR ARRAY Corner support rods allow for full ation access along full segment length in situ calibration access Double ended PMT readout, with light concentrators good light collection and energy Floor has successfully detected antineutr response Concrete Monolith ~5% √ E energy resolution ent close to a reactor full X,Y,Z event reconstruction 119cm Optimized shielding to reduce tilted array for cosmogenic backgrounds calibration access Karsten Heeger, Yale University � 7 Moriond 2019

Background Rejection IBD-like rate per segment n+H rate [mHz/segment] segment z 10 2.15 1.20 0.94 0.86 0.83 0.78 0.79 0.72 0.76 0.82 0.89 1.00 1.18 2.15 2.0 1.36 0.34 0.18 Cosmogenic background 0.14 0.15 0.14 0.15 0.15 0.12 0.14 0.14 0.19 0.35 1.31 PSD 8 1.00 0.17 0.07 0.03 0.04 0.05 0.05 0.04 0.05 0.04 0.05 0.05 0.17 1.03 Simulation 1.5 0.83 0.17 0.03 0.03 0.02 0.04 0.02 0.04 0.04 0.04 0.05 0.04 0.15 0.83 12 C inelastic 6 0.78 0.12 0.04 0.02 0.02 0.02 0.02 0.03 0.02 0.02 0.03 0.03 0.17 0.78 PROSPECT - arXiv:1808:00097 showers 0.75 0.12 0.05 0.03 0.02 0.01 0.02 0.01 0.03 0.03 0.03 0.02 0.11 0.70 1.0 4 0.64 0.13 0.02 0.03 0.03 0.02 0.02 0.01 0.03 0.03 0.03 0.04 0.11 0.69 0.64 0.11 0.03 0.02 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.15 0.64 neutrinos 0.5 2 0.70 0.13 0.04 0.03 0.02 0.02 0.01 0.03 0.01 0.02 0.03 0.04 0.13 0.68 topology Simulation 0.92 0.21 0.10 0.08 0.08 0.06 0.08 0.05 0.05 0.09 0.05 0.10 0.20 0.92 0 1.27 0.69 0.42 0.39 0.35 0.30 0.32 0.32 0.31 0.30 0.36 0.44 0.72 1.34 fiducialization 0.0 0 5 10 segment x Detector design further optimized for background rejection Combine: A sequence of cuts leveraging spatial and timing - PSD characteristics of an IBD yields > 10 4 background Pieter Mumm - Shower veto suppression and signal to background of > 1:1. National Institute of Standards and Technology - Event topology - Fiducialization Rate and shape of residual IBD-like background can be For the PROSPECT Collaboration measured during multiple interlaced reactor-off periods. Karsten Heeger, Yale University � 8 Moriond 2019

Assembly of First Row Assembly in 30s (video) x November 1, 2017

Final Row Installation November 17, 2017

Dry Commissioning Dec 2017 - Jan 2018

– – February 2018 In Position at HFIR Arrival at ORNL Filling from Mixing Tank First Muon Track

– – February 2018 In Position at HFIR Arrival at ORNL Filling from Mixing Tank Hadronic Shower

– – February 2018 In Position at HFIR Arrival at ORNL Filling from Mixing Tank IBD Candidate

Energy Reconstruction Resolution and Reconstruction Gamma sources ( 137 Cs, 60 Co, 22 Na) deployed throughout detector, measure 0.10 rec (a) /E E rec single segment response 0.08 E E Resolution Model 137 σ Cs 0.06 Fast-neutron tagged 12 B: High-energy 22 Na 0.04 22 60 Na Co nH beta spectrum calibration 0.02 Rate [Hz] 60 0.0 0.5 1.0 1.5 2.0 2.5 3.0 (b) 22 Na data 40 Best fit MC Arb. Unit (a) Gamma Sources 0.06 137 Cs 20 137 Cs 60 Co 0.04 0 Best fit MC 0.0 0.5 1.0 1.5 2.0 2.5 3.0 E [MeV] 0.02 rec 60 Co MC (c) 1.04 /E 0 rec 0.5 1 1.5 2 2.5 3 1.02 E 22 Na 22 E [MeV] 60 Na Co rec 1.00 137 0.8 Cs nH Rate [mHz/MeV] 12 (b) B Spectrum 0.98 0.6 4.5% at 1MeV 0.96 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0.4 Average γ Energy [MeV] E[MeV] 0.2 MC/data for calibration peaks agrees to better than 1 σ 0 2 4 6 8 10 12 14 E [MeV] Full-detector E rec within ±1% of E true rec Phys.Rev.Lett. 121 (2018) no.25, 251802 High light collection: 795±15 PE/MeV PROSPECT Collaboration Karsten Heeger, Yale University � 15 Moriond 2019

First Oscillation Analysis Data Set reactor on reactor off reactor on 33 days of Reactor On Events per day Preliminary Correlated 28 days of Reactor Off 1500 Correlated S/B = 1.36 Accidental S/B = 2.25 1000 24,608 IBDs detected maintenance calibration Average of ~750 IBDs/day 500 IBD event selection defined Accidentals and frozen on 3 days of data 0 03/05 03/22 04/08 04/25 05/12 05/30 Date (MM/DD) Phys.Rev.Lett. 121 (2018) no.25, 251802 PROSPECT Collaboration Karsten Heeger, Yale University � 16 Moriond 2019

Neutrino Rate vs Baseline Normalized IBD counts Data Data Data 2 1/r 1 2 A/r 2 fit 1/r 0.8 0.6 PRELIMINARY 7 7.5 8 8.5 9 Baseline (m) Phys.Rev.Lett. 121 (2018) no.25, 251802 PROSPECT Collaboration Observation of 1/r 2 behavior throughout detector volume Bin events from 108 fiducial segments into 14 baseline bins 40% flux decrease from front of detector to back Karsten Heeger, Yale University � 17 Moriond 2019

Neutrino Spectrum vs Baseline Spectral Distortion vs Baseline 2 2 2 2 Data 1.8 1.8 1.8 1.8 6.7-7.1 m 7.1-7.5 m 7.5-8.0 m RAA Rate 1.6 1.6 1.6 1.6 Rate Null oscillation Null oscillation Null oscillation Null oscillation Null Oscillation 1.4 1.4 1.4 1.4 Baseline 1 Baseline 1 0.06 6.7-7.1m Baseline 1 Baseline 1 Baseline 2 Baseline 2 1.2 Full detector spectrum 1.2 1.2 1.2 Ratio Baseline 3 Baseline 3 7.1-7.5m Baseline 2 Baseline 2 Spectrum at baseline Baseline 4 Baseline 4 1 0.05 1 1 1 Baseline 3 7.5-8.0m Baseline 3 Baseline 5 Baseline 5 0.8 0.8 0.8 0.8 Baseline 6 Baseline 6 Baseline 4 8.0-8.4m Baseline 4 1.8 0.04 0.6 0.6 0.6 0.6 Baseline 5 Baseline 5 8.4-8.8m 0.4 0.4 0.4 0.4 Baseline 6 Baseline 6 8.8-9.2m 0.03 0.2 0.2 0.2 0.2 0 2 0 2 0 2 2 0 1 2 3 4 5 6 7 1 1 2 3 4 5 6 7 1 2 3 4 5 6 7 0.02 1.8 1.8 1.8 1.8 8.0-8.4 m 8.4-8.8 m 8.8-9.2 m 1.6 1.6 1.6 1.6 0.01 1.4 1.4 1.4 1.4 1.2 0 1.2 Ratio 1.2 1.2 1 2 3 4 5 6 7 Prompt Energy (MeV) 1 1 1 1 Prompt Energy 0.8 0.8 0.8 0.8 1.8 0.6 0.6 0.6 0.6 0.4 0.4 0.4 0.4 0.2 0.2 0.2 0.2 0 0 0 3 4 0 5 0 Phys.Rev.Lett. 121 (2018) no.25, 251802 0 0 0 1 1 1 2 2 3 3 4 4 5 5 6 6 7 7 1 1 2 2 3 3 4 4 5 5 6 6 7 7 7 1 1 2 2 3 3 4 4 5 5 6 6 7 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 1 2 3 4 5 6 7 Prompt Spectrum(MeV) Prompt Spectrum(MeV) Prompt Spectrum(MeV) Prompt Energy (MeV) Prompt E Prompt Energy (MeV) (MeV) Prompt Energy (MeV) PROSPECT Collaboration rec Compare spectra from 6 baselines to measured full-detector spectrum Null-oscillation would yield a flat ratio for all baselines Direct ratio search for oscillations, reactor model independent Karsten Heeger, Yale University � 18 Moriond 2019

Oscillation Search Results • Feldman-Cousins based confidence intervals for oscillation search RAA best fit • Covariance matrices captures all uncertainties and energy/ baseline correlations Critical 𝜓 2 map generated • from toy MC using full covariance matrix • 95% exclusion curve based on 33 days Reactor On operation • Direct test of the Reactor Antineutrino Anomaly Phys.Rev.Lett. 121 (2018) no.25, 251802 PROSPECT Collaboration Disfavors RAA best-fit point at >95% CL (2.2 𝝉 ) Karsten Heeger, Yale University � 19 Moriond 2019