goddess of light theia

THEIAAn Advanced Liquid Scintillator Detector

Robert Svoboda, CoSSURF2019

Theia, GreekGoddess of Light

Development of Large Optical Detectors have ushered in a new era of Neutrino

Physics

R.Svoboda, CoSSURF 2019

Large size for cost, fast timing for background reduction,low threshold, reconfigurable as the field progressed

New Physics is out there…• CP violation and neutrino mass ordering• Diffuse Supernova Neutrino Background (DSNB) Are they

there? At what level?• Majorana neutrinos (NLDBD to possibly 100 ton scale). A

must to investigate with CP violation.• CNO solar neutrinos and the “New” Solar Neutrino

Problem• “invisible” nucleon decay – signal for extra dimensions?• Geo-Neutrinos – what is the heat budget of the Earth?


Advanced Scintillation Detector Concept (ASDC)arXiv:1409.5864

Fast timing and highefficiency photosensors

New methods for loadingliquid scintillator and formixing with water

Advanced Scintillation Detector Concept (ASDC)


arXiv:1409.5864

Neutron taggingby gadoliniumcapture

Neutrino sign selection via neutrontagging and precisionreconstruction

EGADSANNIE

Series of THEIA Workshops

March 2016

October 2016

March 2017


April 2018

December 2018


THEIA Concept

46 m

46 m

• 20-50 kilotons fiducial• Deep depth (>4000 mwe)• Fast timing high efficiency

photosensors, high coverage• Isotopic loading, possibly wit a

balloon to avoid "wasting"isotope and to achieve longattenuation lengths

• Reconfigurable, capable ofeconomically running for long periods in order to have a broad program

multi-kilotonscale inner vessel

arXiv:1409.5864

New Advances in Technology

• Water-based Liquid Scintillator • Fast, High Quantum Efficiency Photomultipliers • Large Microchannel Plate Photodetectors• Intense, low energy neutrino beams• Loading of scintillator with double beta decay isotopes• Vastly improved image recognition and other software


Water-based Liquid Scintillator


~10

nm

LS

surfactantmolecules

Liquid Scintillator (LS) forms small(~10 nm scale) droplets calledmicelles in water that are stabilized bysurfactant molecules with a hydrophilichead and hydrophobic tail. Micellesform under controlled chemicalconditions and are shown to be stableover year time scales.

Can adjust scintillation yield by changing micelle concentration.

Development at Brookhaven: 2015-2018


This image cannot currently be displayed.

WbLS at the Advanced Instrumentation Testbed (AIT)

• The AIT will pursue enhanced capabilities for monitoring nuclear reactors. AIT will permit R&D into detection media, photodetectors, methods and algorithms.

• This includes technology important for THEIA, i.e. Water-based Liquid Scintillator for possible future deployment as WATCHMAN upgrade.

Joint U.S./U.K. WATCHMAN Project now under constructionat Boulby Underground Lab

Cherenkov/Scintillation light separation

• In principle, one could get tracking information from Cherenkov light and calorimetric information from scintillation light

• Can be done by timing, color filters, or some combination of the two


1 GeV β, 5% WbLS, 50kt, 90%

Large Area Picosecond PhotoDetector (LAPPD)


Now manufactured and marketedby Incom, these devices give ~2mmspatial resolution and ~70 psectiming resolution.

Now being tested in the ANNIEexperiment at FNAL

Pinhole resolution on masked LAPPD

G.D. Orebi Gann

Accelerator Neutrino Neutron Interaction Experiment


ANNIE Physics Motivation

Martini, Ericson, Chanfray - arXiv 1211.1523v2

To turn neutrino physics into a precision science we need to understand the complex multi-scale physics of neutrino-nucleus interactions

• Dominant source of systematics on future long-baseline oscillation physics

• Possible source of uncertainty in short-baseline anomalies

• We need comprehensive and precise measurement for a variety of targets/Eν

ANNIE is a final-state X + Nn program to complement X + Np measurements in LAr

The presence, multiplicity and absence of neutrons is also a strong handle for signal-background separation in a number of physics analyses!

μ-

νμ

FermilabBNB

1. CC interaction in the fiducial volume produces a muon, reconstructed in the water volume and MRD

2. Neutrons scatter and thermalize3. - 4. Thermalized neutrons are captured on the Gd producing flashes of light

ANNIE Experimental Design

ANNIE will begincommissioning in this summer, with firstBeam data Fall 2019

Use of LAPPDs critical for ANNIE


ANNIE will use 5 LAPPDs to improve kinematic reconstruction of neutrino interactions. Simulations show that this is a great improvement of PMT-only reconstruction. This is also an important test for THEIA.

ANNIE – coming soon!

Where to build Theia?• Deep depth is critical for solar neutrinos, invisible nucleon

decay, and NLDBD to avoid spallation backgrounds. • Deep depth important for DSNB and Geo-neutrinos• Need a large (20-40 kT) cavern. Difficult for very deep labs like

SNOLAB. Also issues with being in an operating mine.• Need an intense neutrino beam for CP violation and mass

ordering. ON AXIS preferred to maximize flux. Kamioka Lab is off-axis (and somewhat too shallow)


Could Theia go into the LBNF?


• New 5th Experimental Hall• Planned Experimental Hall as part of

the DUNE Project• Post-DUNE (a long wait!)

Theia in a generic Experimental Hall at LBNF that would take up half a cavern

• A 20x20x70 meter Experimental Hall would hold 28 kT total and 17 kT fiducial

• Cost could potentially fit into NSF mid-scale program

• What physics sensitivity could be achieved?


Redesigned LBNF Beam enhances on-axis sensitivity

R.Svoboda, UC Davis 24

Redesigned LBNF Beam enhances on-axis sensitivity

R.Svoboda, UC Davis 25

Let’s assume Theia would do as well as the existing Super-K performance


E.Worcester, BNL

(i.e. ignore faster modern PMTs, WbLS, LAPPDs, improved image processing)

3.5 years neutrino, 3.5 year antineutrinoEvent rate versus reconstructed neutrino energy

New SK techniques includemulti-track events

17 kT Theia can add to the DUNE sensitivity at a similar scale to a 10 kT liquid argon module


This image cannot currently be displayed.This image cannot currently be displayed.

E.Worcester, BNL

Solar CNO flux


• Our sun is located on the Main Sequenceat the crossover point between pp and CNO

• There is a 30% disagreement between stellaratmosphere models and SSM metallicity andhelioseismology measurements.

• CNO measurement could help resolve this

BOREXINO results are limited by spallationbackgrounds, especially 11-C and 210-BiarXiv:1810.12967

Prediction: 3.5-4.9 cpd/100t, Borexino limit: <8.1 cpd/100t

Solar CNO flux


• The great depth of SURF suppresses the 11-C spallation production• 5% WbLS with 25o directional resolution from C/S light separation would

suppress 210-Bi (assuming SNO levels of water purity)

R. Bonventre and G. Orebi Gann, Eur. Phys. J. C (2018) 78: 435

• Potential for 6% CNO measurementafter 7 years

• Limiting background is now 40-K• Downside: assumes 90% photocoverage.

similar to JUNO

Theia Sensitivity to the Diffuse Supernova Flux


This image cannot currently be displayed.

• Sum of all SN predicts roughly1 IBD event/10 kT/year

• Major backgrounds from atmospheric NC events withneutron in the FS

• Measuring C/S ratio in 5%WbLS is an effective way tosuppress this backgroundas nuclear fragments havevery different ratio thanpositrons

• A 17 kT Thiea would have asensitivity better than orequal to SK-Gd

Before C/S cut After C/S cut

Other THEIA Physics

• Potential Site for future NLDBD experiment• Supernova neutrinos with low threshold and

ring imaging • Geo-ν at a mid-continent location• Baryon number violation to unique modes such

as n-> 3ν (if WbLS is used)


Summary


• Advances in LS technology and photosensors make possible a hybrid WC/LS detector that could be located deep underground, with the LBNF as an ideal site

• Very broad and flexible physics program at deep (4200 mwe) and remote (from reactors) site that will also have a powerful neutrino beam.

• Very active and ambitious R&D program, including the ANNIE and WATCHMAN experiments

Theia Interest Group Meetingat Mainz

Backup


Another Example: Nucleon Decay: n3ν


Type of decay associated with Large Extra Dimension (LED) theories. These postulate 100-1000 TeVscale gravity rather than Mplanck

CURRENT:KamLAND: 5.8x1029 yearsSNO: 2x1029 yearsSNO+: 2.5x1029 years

16O has 1p decay, 12C does not

Deep depth and WbLS wouldallow THEIA to improve theseby 2 orders of magnitude

Neutron yield from neutrino interactions is an important indicator of inelasticity in 1 GeV neutrino interactions


GENIE simulation of 1 GeV of muonmuon neutrino interactions on waterwith 1µ 0π in the final state. Plots show the effects on energy reconstruction from Fermi motion and inelastic processes.

No neutrons in final state 1 or more neutrons in final state

Total

stuck pion

2p-2h

Solar CNO flux precision as a function of angular resolution


R. Bonventre and G. Orebi Gann, Eur. Phys. J. C (2018) 78: 435

goddess of light theia

Documents