Reactor Neutrinos Sterile Neutrino Searches with Precision - PowerPoint PPT Presentation

Reactor Neutrinos Sterile Neutrino Searches with Precision Measurements at Very Short Baselines Jim Napolitano Temple University for the PROSPECT collaboration Amherst Center for Fundamental Interactions 14-16 December 2015

Reminder: The Reactor Neutrino Anomaly 1.2 Data / Prediction 1 Previous data Deficit 0.8 Daya Bay Global average 1- Experiments Unc. σ 1- Model Unc. σ 0.6 3 2 10 10 10 Distance (m) Is the deficit due to antineutrino disappearance? Napolitano: Sterile Neutrinos at Reactors 2 UMass AFCI 14-16 Dec 2015

Reminder: The Reactor Neutrino Anomaly 1.2 “Kopp Best Fit”: Point Source @4 MeV Data / Prediction 1 Previous data Deficit 0.8 Daya Bay Global average 1- Experiments Unc. σ 1- Model Unc. σ 0.6 3 2 10 10 10 Distance (m) Is the deficit due to antineutrino disappearance? Napolitano: Sterile Neutrinos at Reactors 2 UMass AFCI 14-16 Dec 2015

Reminder: The Status of Sterile Neutrinos Δ m 2 ≈ few ev 2 and sin 2 2 θ “not so small” ] 2 [eV 10 References 14 2 m ∆ Gallium PRC 83(2011)065504 1 BOONE, MiniBOONE AnnRev 63(2013)45 Global fits 1 − 10 Sensitivity: JHEP 1305(2013)050 ν Disappearance (Giunti), 2 σ CL e SBL Reactor + Gallium Anomaly (LSN), 95% CL PRD 88(2013)073008 SBL Reactor Anomaly (Kopp), 95% CL All Disappearance Expts (Kopp), 95% CL ν e Gallium Anomaly (Kopp), 95% CL 2 − 10 2 1 − − 10 10 1 2 sin 2 θ 14 Napolitano: Sterile Neutrinos at Reactors 3 UMass AFCI 14-16 Dec 2015

Reactor Anomaly and Reactor Calculations Power Reactors: Mixture of 235 U, 239 Pu, 241 Pu, 238 U 1.7 / fission / GW / day Daya Bay (stat.) 6.4 Daya Bay w/ fission fraction corr. (stat.) Daya Bay near site combined (syst.) 2 cm Huber + Mueller Reference: 6.2 2 cm ILL + Vogel -43 arXiv 1508.04233 1.6 10 -18 10 × 6.0 f × σ Y 5.8 1.5 AD1 AD2 AD3 AD4 AD5 AD6 Model ILL+Vogel (1980’s): e − spectra, plus calculation for 238U Huber + Mueller (2011): Inversion with β -decay corrections Napolitano: Sterile Neutrinos at Reactors 4 UMass AFCI 14-16 Dec 2015

More Reactor Surprises: The “Bump” Daya Bay RENO Data (a) Near 20000 Full uncertainty 15000 Entries / 250 keV Reactor uncertainty Events / 0.2 MeV Events / 0.2 MeV Data 15000 ILL+Vogel MC 10000 10000 Integrated 5000 5000 2 4 6 8 Prompt Positron Energy (MeV) Ratio to Prediction 1.2 (Huber + Mueller) 1.1 1 0.9 (Data - MC) / MC (Data - MC) / MC 1 2 3 4 5 6 7 8 0.2 0.8 1 2 4 6 8 Prompt Energy (MeV) 4 0.1 contribution 10 2 10 0 ) i 0 ∼ χ 10 ( 10 2 − 0.1 − 2 10 χ 4 − 1 2 3 4 5 6 7 8 10 2 4 6 8 Prompt Energy (MeV) Prompt Energy (MeV) arXiv 1508.04233 arXiv 1511.05849 Napolitano: Sterile Neutrinos at Reactors 5 UMass AFCI 14-16 Dec 2015

➥ New “Direct” Reactor Calculations Huber-Mueller uncert. Different approaches Normalized Ratio to Huber-Mueller JEFF-3.1.1 ENDF/B-VII.1 1.15 Daya Bay (and nuclear data bases) 1.1 give different results, and 1.05 may point to 238 U as the 1 source of “The Bump.” 0.95 0.9 2 3 4 5 6 7 E Prompt (MeV) ] -1 Nuclear Calculation fission 0.2 - (c) β Conversion, Huber - β Conversion, Mueller Huber-Mueller uncert. -1 Normailzed ratio to Huber-Mueller ) [MeV Nuclear Calc., Fallot JEFF-3.1.1 ENDF/B-VII.1 1.15 RENO ν 0.1 S(E 1.1 × ν σ 1.05 ) 2 3 4 5 6 7 8 ν Daya Bay (E RENO 1 1.1 conv. Double CHOOZ - β 1 ) / S 0.95 ν 0.9 S(E (d) 0.9 0.8 1 2 3 4 7 5 6 2 3 4 5 6 7 8 E Prompt (MeV) Antineutrino Energy [MeV] PRL 114(2015)012502 PRD 92(2015)033015 Napolitano: Sterile Neutrinos at Reactors 6 UMass AFCI 14-16 Dec 2015

Nuclear Power Plant Reactors Daya Bay, et.al., use “Near+Far” for oscillations, but… Napolitano: Sterile Neutrinos at Reactors 7 UMass AFCI 14-16 Dec 2015

Nuclear Power Plant Reactors Daya Bay, et.al., use “Near+Far” for oscillations, but… • Nuclear fuel evolution uncertainty Napolitano: Sterile Neutrinos at Reactors 7 UMass AFCI 14-16 Dec 2015

Nuclear Power Plant Reactors Daya Bay, et.al., use “Near+Far” for oscillations, but… • Nuclear fuel • Relatively evolution large size of uncertainty reactor core (Research) Napolitano: Sterile Neutrinos at Reactors 7 UMass AFCI 14-16 Dec 2015

Nuclear Power Plant Reactors Daya Bay, et.al., use “Near+Far” for oscillations, but… • Nuclear fuel • Relatively evolution large size of uncertainty reactor core (Research) • Hard to get within meters of the reactor core • Restricted information and no control over source Napolitano: Sterile Neutrinos at Reactors 7 UMass AFCI 14-16 Dec 2015

Nuclear Power Plant Reactors Daya Bay, et.al., use “Near+Far” for oscillations, but… • Nuclear fuel • Relatively evolution large size of uncertainty reactor core (Research) • Hard to get within meters of the reactor core • Restricted information and no control over source ➥ Nuclear power plants are not ideal sources for Sterile Neutrino Searches Napolitano: Sterile Neutrinos at Reactors 7 UMass AFCI 14-16 Dec 2015

Precision Experiments at Research Reactors See http://aap2015.phys.vt.edu • STEREO @ ILL J. Phys. Conference Series 593(2015)012005 • SOLID @ BR2 MTR https://www2.physics.ox.ac.uk/research/mars- project/solid • NEOS @ HANBIT #5 (Power Reactor!) (See AAP conference presentations) ★ PROSPECT @ HFIR Recent full description at arXiv:1512.02202 Napolitano: Sterile Neutrinos at Reactors 8 UMass AFCI 14-16 Dec 2015

SoLiD and STEREO SoLi ∂ BR2 ha reactor core 5.5 m SoLid detector modules distance Energy Napolitano: Sterile Neutrinos at Reactors 9 UMass AFCI 14-16 Dec 2015

PROSPECT A PRecision Oscillation and SPECTrum measurement using an array of functionally independent detectors See arXiv:1512.02202 • Collaboration: BNL, Drexel, IIT, Le Moyne, LLNL, NIST, ORNL, SYSU, Temple, Tennessee, Waterloo, William & Mary, Wisconsin, Yale • High Flux Isotope Reactor (HFIR) at ORNL • Phase I: Single movable detector ≈ 7m from core, definitive exclusion of “Kopp Best Fit” region • Phase II: Second detector at greater distance, for complete exclusion of allowed region Napolitano: Sterile Neutrinos at Reactors 10 UMass AFCI 14-16 Dec 2015

Schematic of the Experiment Phase I Detector 180 cm HFIR Core 7 to 10 meters Napolitano: Sterile Neutrinos at Reactors 11 UMass AFCI 14-16 Dec 2015

Schematic of the Experiment Phase I Detector 180 cm e + Scintillator p Liquid ν̅ e 15 cm ν̅ e HFIR Core 7 to 10 meters Napolitano: Sterile Neutrinos at Reactors 11 UMass AFCI 14-16 Dec 2015

Schematic of the Experiment Phase I Detector n+ 6 Li → α +t 180 cm n e + Scintillator p Liquid ν̅ e 15 cm ν̅ e HFIR Core 7 to 10 meters Napolitano: Sterile Neutrinos at Reactors 11 UMass AFCI 14-16 Dec 2015

Schematic of the Experiment Phase I Detector n+ 6 Li → α +t Detection is 180 cm contained in n single cell (or e + neighbors) Scintillator p Liquid ν̅ e 15 cm ν̅ e HFIR Core 7 to 10 meters Napolitano: Sterile Neutrinos at Reactors 11 UMass AFCI 14-16 Dec 2015

������ ������ ������������������� Realization: Phase I (b) AD-I Active Volume (d) AD-I Segments and Containment (a) PROSPECT Phase I Reactor 200.0 cm 120.0 cm Shielding 78.74 47.24 2000 1200 (c) AD-I Unit Segment Section A-A AD-I LiLS SECTION A-A Passive 120 cm Segments Shielding 146.5 cm 170.0 cm 14.6 cm 14.6#cm# 66.93 57.50 Separator 1700 1460.5 A A HFIR Core 14.6 cm 14.4#cm# 14.6#cm# 14.4#cm# Corner 175.3 cm 69.00 Rod 1752.6 230.0 cm 90.55 b# 2300 source deployment system optical calibration system routing between segments antineutrino detector with string and guide tubes with string and guide tubes and PMT modules with optical and source calibration optical fiber motor system detector segments source path detector fiber+sleeve+diffuser segments Napolitano: Sterile Neutrinos at Reactors 12 UMass AFCI 14-16 Dec 2015

Extended Capability: Motion & Phase II Antineutrino Detector I Antineutrino Detector II HFIR Core Napolitano: Sterile Neutrinos at Reactors 13 UMass AFCI 14-16 Dec 2015

Extended Capability: Motion & Phase II Antineutrino Detector I Antineutrino Detector II HFIR Core In Phase I the detector can move ≈ 3m Napolitano: Sterile Neutrinos at Reactors 13 UMass AFCI 14-16 Dec 2015

Extended Capability: Motion & Phase II Antineutrino Detector I Antineutrino Detector II HFIR Core In Phase I the detector can Second detector for greater move ≈ 3m coverage in Phase II Napolitano: Sterile Neutrinos at Reactors 13 UMass AFCI 14-16 Dec 2015

High Flux Isotope Reactor (HFIR) https://neutrons.ornl.gov/hfir • 85 MW, highly enriched 235 U, light water moderated • Regular reactor-on periods lasting 25 days, with roughly equal periods of down time in between • Well understood reactor core, including simulation Fuel 60 cm 37.5 cm Napolitano: Sterile Neutrinos at Reactors 14 UMass AFCI 14-16 Dec 2015