The The Scie Scientif ific I ic Impact mpact o of W Water- - - PowerPoint PPT Presentation

The The Scie Scientif ific I ic Impact mpact o

• f W

Water- based Li Liquid Scintillator Hybrid De Detector

• rs

R.Svoboda CPAD, 8 December, 2019

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

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

R.Svoboda, CPAD 2019

Wa Water Cherenkov Li Liquid Sci cintillator

• Excellent Transparency
• large size
• Directionality
• Particle ID
• Potential for large Isotopic Loading
• High Light Yield
• low threshold
• good energy resolution
• Can be radiologically very clean

Could we make a hybrid detector?

R.Svoboda, CPAD 2019

Directionality Low threshold and high energy resolution Super-K Borexino

Why would you want a Hybrid Detector?

• Cherenkov has directionality and kinetic energy, while scintillation

carries information on the total deposited charge and PID

• There is different information contained in the Cherenkov and

scintillation light that can enable enhanced PID via the C/S ratio

• Improved energy resolution via enhanced light yield
• Detection of below Cherenkov threshold particles. E.g. stealth

muons, kaons from proton decay, and low energy charged hadrons

• Lower energy threshold due to addition of scintillation light

R.Svoboda, CPAD 2019

How to Separate Cherenkov and Scintillation Photons?

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Timing Color

Kaptanoglu, Luo, and Klein

• JINST. 14 (2019)

J.R.Alonso, et al arXiv:1409.5864 Cherenkov light comes early Scintillation light has narrow bandwidth

R.Svoboda, CPAD 2019

New hybrid target media Novel photosensors Advanced simulation and reconstruction

LAPPDs

Chroma optical simulations - GPU

Water-based Liquid Scintillator

(see talk by J.Caravaca) (see talks by A.Lyashenko, H.Frisch, J.Xia, E.Angelico, E.Tiras) Dichroicon (see talk by T.Kaptanoglu)

Super-K FitQun:

• J. Phys. Conf.
• Ser. 888
• no. 1, (2017)

LENA 3D topological reconstruction: JINST 13 no. 07, (2018)

R.Svoboda, CPAD 2019

(see talk by E.Tiras)

• Gadolinium neutron tagging
• LAPPD reconstruction
• WbLS (planned)

A series of workshops over last 4 years has led to a White Paper on the the physics potential of a hybrid detector known as the Thei eia concept

March 2016 October 2016 March 2017 April 2018 December 2018

(arXiv:1911.03501)

(to be submitted this week to Euro. Phys. J. C) Theia International Interest Group

Theia: Goddess of Light

R.Svoboda, CPAD 2019

R.Svoboda, CPAD 2019

THEIA25

70m 20m 18m

Theia100

(arXiv:1911.03501)

The White Paper considers two versions of the Theia concept, both assumed to be sited at the LBNF Theia25: 25 kTon (total) hybrid detector as the 4th DUNE module Theia100: 100 kTon (total) hybrid detector as a future stand-alone experiment

interior of Theia25

Theia concept: a reconfigurable detector

R.Svoboda, CPAD 2019

(arXiv:1911.03501)

Theia would have a very broad science program based on the ability to upgrade the detector in incremental steps to “follow the science” This table shows a possible scenario with three phases of detector configurations

Long Baseline Physics

• In the last 10 years there

have been huge strides made in the analysis of water Cherenkov data by SK/T2K

• >70% reduction in p0

backgrounds

• ability to reconstruct multi-

track events so that more than 50% increase in signal in 2-3 GeV region

R.Svoboda, CPAD 2019

+ + other

multi-track samples

Old LBNE studies based on SK-1 current SK/T2K analysis NC NC

Long Baseline Physics

• As a result, using the existing Super-

K/T2K efficiencies and background rejection, Theia100 (70 kTon fiducial) would have excellent CPV sensitivity

• Theia25 (17 kTon fiducial) would have

sensitivity comparable to one DUNE Lar module - appropriate for 4th module

• Possibility for additional

improvements using C/S information and fast timing needs to be explored

R.Svoboda, CPAD 2019

π /

CP

δ

• 1 -0.8 -0.6 -0.4 -0.2

0.2 0.4 0.6 0.8 1

2

χ ∆ = σ 1 2 3 4 5 6 7

CP Violation Sensitivity

π /

CP

δ

• 1 -0.8 -0.6 -0.4 -0.2

0.2 0.4 0.6 0.8 1

2

χ ∆ = σ 1 2 3 4 5 6 7

Theia 70 kt Theia 17 kt DUNE 10 kt (CDR)

CP Violation Sensitivity Normal Ordering 7 years

CP Violation Sensitivity

using DUNE CDR assumptions: 2% signal and 5% background uncertainty

Diffuse SN Background

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LBNF is a very deep site (4300 mwe) far from nuclear reactors

• reduction in spallation backgrounds
• small reactor background

Neutron tagging possible w/o gadolinium

• assume 10% WbLS and 70% coverage

C/S ratio

• strong cut against NC events that can

result in neutrons similar to inverse beta decay events Theia 100 kTon-year exposure before cuts after cuts Conclusion: even Theia25 could be large enough to make a 5s discovery

• f the DSNB in less than 10 years

SN Burst Neutrinos

R.Svoboda, CPAD 2019 100 kT WbLS @ 10 kpc

Theia100(25) would see nearly 1000(250) Electron Scattering (ES) events Possibility of 7-Li loading for solar neutrinos would make Theia sensitive to ne CC events beyond just ES

Solar Neutrinos

• The CNO flux from the sun has never been measured directly and is

critical to the resolution of the solar metallicity problem. A Theia detector could measure this using directionality in addition to scintillation using Electron Scattering (ES) events (assuming very high light collection - similar to JUNO)

• Spectral upturn and Day/Night effect in 8-B can probe the energy

region of the vacuum to matter transition

• A Theia detector could also be loaded with 7-Li for enhanced CC

detection

R.Svoboda, CPAD 2019

Solar Neutrinos

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90% PMT coverage, 5% WbLS, 0.6 MeV threshold, 25o angular resolution, 250 kT-years

• Eur. Phys. J. C 78 (2018) 4a35, arXiv:1803.07109

Bonventre and Orebi Gann have explored the possibility of directional fitting in a WbLS detector of 50 kT Applied to a Theia detector, this would result in a definitive measurement of CNO (from Theia White Paper)

Possibility of 7-Li loading: enhanced sensitivity to ne

R.Svoboda, CPAD 2019

7-Li ne and other CC cross-sections. Note that 7-Li loading would be in WbLS The ability to make a solar direction cut to remove ES events results in an much enhanced capability

before ES cut after ES cut

Note: 7-Li loading would also anable detecting ne CC in a SN burst

Reactor and Geoneutrinos

R.Svoboda, CPAD 2019

The reactor background at the LBNF is very low The flux of Geoneutrinos (26/kT-year)is comparable to the reactor flux (20/kT-year). A Theia detector would make a definitive measurement

Neutrinoless Double Beta Decay

R.Svoboda, CPAD 2019

3s discovery potential for proposed future experiments This shows results for Theia100 with an 8 meter radius inner vessel and 90% PMT coverage

3% enriched 136-Xe 5% nat-Te

What’s Next?

• Need to now make a hit-level reconstruction analysis for the LBL physics

sensitivity studies that will go beyond simply taking existing Super-K efficiencies and resolutions. How can the fast timing and hybrid signal be exploited? A multi-university consortium is forming to propose a two-year program of detailed detector and physics simulations.

• Need to pursue the further development of WbLS to determine stability,

attenuation and scattering, effects on materials, and how to achieve required optical and radiological purity. There is a separate university/lab consortium that has formed to propose a coherent R&D program

• Photosensor development (e.g. LAPPDs and Dichroicons) is proceeding

under the current program, and should have continued support.

R.Svoboda, CPAD 2019

Summary

• The development of hybrid target materials, ultra-fast and color

sensitive photosensors, and advanced imaging techniques have led to the maturing of the concept of a modern, large scale optical detector

• Such a detector would be reconfigurable and able to adapt to new

scientific discoveries and directions.

• There are many talks at this workshop on technology relevant to a

Theia concept detector - ranging from novel photosensors, to ultra- fast beam timing ideas, to new types of scintillators. There is a lot of community interest and lots of opportunity for bold, new thinking

• The next Theia international meeting will be in Spring 2020 - think

about attending!

R.Svoboda, CPAD 2019

R.Svoboda, CPAD 2019

R.Svoboda, CPAD 2019

R.Svoboda, CPAD 2019