Post on 26-Mar-2022
PROSPECT: A Precision Reactor Oscillation and Spectrum
ExperimentXianyi Zhang
Illinois Institute of TechnologyPROSPECT Collaboration
1
The Reactor Antineutrino
❖ Fission reactors generate antineutrinos through β-decay.
❖ Mainly 4 fission source isotopes of reactor antineutrino.
❖ Reactor antineutrino experiments:➢ Antineutrino spectrum of
fission reactor.➢ Oscillation of reactor
antineutrino.
2
Neutrino Oscillation and Spectrum, arXiv:1503.01059
The Reactor Antineutrino Anomaly
❖ The latest neutrino flux measurement of Daya Bay experiment showed deficit from prediction.
❖ The spectral prediction models of reactor antineutrino are different.
❖ Latest multi-baseline reactor experiments found deviation of neutrino spectrum.
3
Spectrum Predictions, arXiv:1470.1281 DYB Spectrum and Flux, arXiv:150804233
PROSPECT Experiment
❖ Reactor: a Highly Enriched Uranium (HEU) reactor - High Flux Isotope Reactor, at ORNL.
❖ Baseline: 7 - 12 m (movable).❖ Detector: optically segmented Li-6
loaded liquid scintillator (LiLS) antineutrino detector.
4
Physics Goal - Probe a Sterile Neutrino
Flux deficit: a possible hint of oscillation from antineutrino to a sterile neutrino.
❖ A right-handed singlet of neutrino.❖ One sterile neutrino is suggested with a
Δm2 ~ 1 eV2.
5
Oscillated spectra on baselines
Null-oscillated spectra on baselines
Sensitivity of oscillation of PROSPECT
PROSPECT Cross-section
Phase I + II
Phase I
DayaBay
Physics Goal - Spectrum Measurement
❖ Direct spectral measurement to the Highly Enriched Uranium (HEU) reactor, σ=4.5%/√E.
❖ Compare the absolute spectrum of reactor antineutrino with recent models of spectrum.
❖ Set new reference of reactor spectrum for future reactor antineutrino experiments.
6
The Antineutrino Detection
❖ Detect Inverse Beta Decay (IBD) of antineutrino.❖ The e+ event (prompt event) and n-capture event
(~40μs delayed event) of LiLS generated scintillation light.
❖ Photomultiplier Tubes (PMT) detect scintillation light.
❖ The Pulse Shape Discrimination (PSD) of scintillator to distinguish the signal from backgrounds.
7
Inverse Beta Decay
Cf-252(n, Li)
n
γ
IBD-like Fast neutron
Accidental γ
Detector Design
❖ Optically segmented by reflectors.❖ The segmentation makes 12x10 elongated elemental ADs (cells).❖ Each elongated cell has PMTs attached on both sides, enabling position
reconstruction of the IBD events.
8
Progress
9
● Background survey and prototype studies have been ongoing since 2014. (Will be presented in P. Surukuchi’s talk.)
● A 2-cell prototype is in plan to test the segmentation of detector.
● Preparing the hardware for construction are in progress, including reflector fabrication, reflector evaluation, mechanical and compatibility tests.
● Simulations for experiment is underway.
Prototype StudiesResearch and Development
Summary
❖ Reactor antineutrino anomaly gives hint of possible new physics and incomplete reactor model.
❖ The PROSPECT experiment aims to measure the spectrum and flux of antineutrino from HFIR in short baseline to explain the anomaly.
❖ The R&D of PROSPECT detector is ongoing. Prototypes of PROSPECT have been deployed.
❖ During the experiment, we will test best fit at 3σ in 1 year, the favor region of oscillation at 3σ in 3 years. Phase II will test the region at 5σ.
11
Backup - Phase II
13
Motivation:
❖ Measurement covers more oscillation cycles.❖ Increase the statistical uncertainty.
Parameters:
❖ Baseline: 16 - 20 m.❖ Target mass: ~10 t.❖ Segmented IBD detector.
PROSPECT Phase II, 16 - 20 m
PROSPECT Phase I, 7 -12 m
Backup
14
A 3x3 mockup will be built to demonstrate the mechanics of the detector by 2016
● Commission the detector. 2016 - 2017● A possible Phase II.
● PROSPECT starts data taking. 2017 - 2020● Measure the spectrum and flux of antineutrino
generated from HFIR.● Look for the signature of sterile neutrino.