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Near Detectors for Hyper-Kamiokande and the T2K Upgrade Mark Rayner (University of Geneva) for the Hyper-K Proto Collaboration 25 Aug 2016 Rencontres du Vietnam 2016: NuFact ad maiorem Dei gloriam

Near Detectors for Hyper-Kamiokande and the T2K Upgrade

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Page 1: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-Kamiokande�and�the�T2K�UpgradeMark�Rayner�(University�of�Geneva)�for�the�Hyper-K�Proto�Collaboration25�Aug�2016

Rencontres�du�Vietnam�2016:�NuFact

ad maiorem Dei gloriam

Page 2: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 2

From�T2K�to�T2K-II�and�Hyper-Kamiokande

x25

x3 1.2 MW

0.56 Mton

???

Page 3: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 3

T2K�Systematics�on�Predicted�Event�Rates�at�Super-K

would�benefit�from��same�nuclear�target

make�a�direct�measurement�of�intrinsic�νe�and�NC�backgrounds

need�a�pure,�high��statistics�sample�of�νe

ν-mode ν-̅mode ν-mode ν-̅mode#�e-like�rings #�μ-like�rings

Page 4: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 4

Pros/Cons�of�a�Generic�Water�Cherenkov

• Pros:�

• Same�target�nuclei�as�the�far�detector�

• 4π�coverage�to�match�the�far�detector�

• Large�fraction�of�active�mass�

• Direct�measurement�of�intrinsic�νe�and�NC�backgrounds�

• Good�e/μ�and�e/π0�separation�

• Cons:�

• No�charge�identification�(gadolinate!)�

• No�direct�detection�of�below�Cherenkov�threshold�particles

We�will�report�our�progress�in�optimizing�such�a�near�detector�for�Hyper-Kamiokande,�and�discuss�how�an�upgraded�ND280�detector�will�be�complementary

Page 5: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 5

nuPRISM�

• Tall�detector�spans�1°�to�4°�off-axis�angle�for�studying�energy�dependence�of�neutrino�interactions�

• Located�at�~1�km

Current�Proposals�for�~1km�Water�Cherenkovs

TITUS�

• Located�2.5°�off-axis�(in�the�same�direction�as�Tochibora)�at�1.8�km�

• Long�geometry�for�high�momentum�muon�containment��

• Gd-loading�for�neutron�detection�

• Magnetized�muon�range�detector�

• 1.27�kton�FV�(max.�without�pile-up)

The�process�for�merging�the�two�proposals�into�a�single�detector�design�with�off-axis�span�and�Gd�has�started�

arXiv:1606.08114�[physics.ins-det]

arXiv:1412.3086�[physics.ins-det]

50 m

Page 6: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

6Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016

This�is�an�event�display�of�a�simulated�anti-muon�neutrino�event�in�TITUS

•40%�photo-coverage�•~3�thousand�12’’�PMTs

TITUS�motivation�and�strategy�• Same�target�(water):�minimize�model�syst.�• Ability�to�separate�the�final�states�as�in�

ND280�(ν/ν�̄and�different�interaction�modes)�• Minimize�the�contribution�to�errors�due�to�

the�flux�(similar�at�2km)�• Full�4π�coverage�and�full�spectrum�• Optimized�for�T2K-II�too

Page 7: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 7

Electron-Like�Ring�Samples�in�TITUS

ν-̅modeν-mode

•νeCC0π�efficiency�~�80%�

•Significant�NC�background�dominated�by�π0�prodction�

•Same�event�selection�and�fiducial�volume�cuts�are�applied�as�in�Super-K�

•Designing�tighter�TITUS�PID�cuts�to�provide�a�purer�νe�sample�

•These�samples�reduce�the�total�νe�event�rate�sytematic�budget�to�3�-�4%�

•See�arXiv:1606.08114�[physics.ins-det]�for�details

Page 8: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

8Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016

This�is�an�event�display�of�a�simulated�anti-electron�neutrino�event�in�TITUS

This�time�the�neutron�is�captured�on�Gd,�and�tagged.

Clear�n�signals�can�be�modified�by�nuclear�effects:�re-scattering,�charge�exchange,�and�absorption�in�the�nuclear�media.�Statistical�information�remains�—�powerful�approach�for�H2O.

Page 9: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 9

Effect�of�neutron�tagging�on�the�samples

In ν-̅mode: require Nneutrons ≥ 0

ν ̅purity increases from 61% to 73%

reconstructed�EQE�(GeV)

In ν-mode: require Nneutrons = 0 (n veto)

EQE�-�EνEν

energy�resolution

νQE purity increases from 74% to 83%, and improves Eν resolution

Additionally, the background samples are useful for constraining syst.

Page 10: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 10

•1.3�MW�beam�

•1:3�POT�ratio�for�ν:ν�̅running�

•Hyper-K�+�TITUS�can�determine�CPV�

•for�62%�of�δCP�at�the�5σ�level�

•for�79%�of�δCP�at�the�3σ�level�

•Resolution�on�δCP�

•ND280�����������12.4°�

•current�systematics!!�

•will�obviously�improve��

•TITUS�(no�Gd)��8.9°�

•TITUS�(w/�Gd)��7.8°�

•no�syst.�������������4.6°�

•This�is�an�initial�study.�A�more�detailed�analysis�is�in�preparation.�See�the�TITUS�article�arXiv:1606.08114

Hyper-K�δCP�sensitivity�study�with�TITUS�

TITUS�Preliminary

TITUS�Preliminary

*Current, not extrapolated!

*

Page 11: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 11

Magnetized�Muon�Range�Detector�

•Magnetized�iron�tracking�detector�with�a�1.5T�field�

• 13m�radius,�2m�thickness�downstream�

•Optimise�first�3�layers�for�0.6GeV�beam�peak�with�double�scintillator�planes�and�10cm�air�gaps�

•Measures�charge�of�forward�muons�up�to�2GeV�

•Calibrate�Gadolinium�technique�

• Smaller�side�MRD�to�probe�high-Q2�phase�space

Page 12: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 12

The�NuPRISM�Detector

Page 13: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 13

NuPRISM�Motivation�• The�primary�feature�of�NuPRISM�is�to�address�the�fact�that�the�near�and�far�detectors�have�different�spectra�(due�to�oscillations)

•Nuclear�effects�that�have�a�small�effect�in�the�near�detector�(right)�can�have�a�large�effect�in�the�far�detector�(left)

Page 14: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

14Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016

reco�pμreco�cosθ

μ

reco�pμreco�cosθ

μ

reco�pμreco�cosθ

μ

reco�pμreco�cosθ

μ

true�Eν

true�Eν

true�Eν

true�Eν

3.5�GeV2.0�GeV0�GeV

FITHK�osc.�flux make�

the�same�linear�

combination:

does�this��match�HK?

REPEAT�FOR�ALL�OSCILLATION�PARAMETER�COMBINATIONS…

predicted��1km�flux�at�4.0°

predicted��1km�flux�at�2.5°

predicted��1km�flux�at�1.0°

measure�off-axis�angle�

event�dists:

3�GeV/c0�GeV/c

1.0°

2.5°

4.0°

θo.a.�

Page 15: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 15

νμ�disappearance�• Linear�combinations�of�NuPRISM�off-axis�fluxes�reproduce�the�far�detector�spectrum�with�oscillation�hypothesis�applied�

• The�linear�combination�of�off-axis�NuPRISM�measurements�are�used�to�predict�the�reconstructed�energy�distribution�at�the�far�detector�

•we�have�bypassed�model�uncertainty!�

• The�4%�systematic�error�estimated�using�ND280�is�reduced�to�1%�with�NuPRISM

Page 16: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 16

Simulation/Reconstruction�• 40%�photo-coverage�and�8’’�PMTs��

• These�8’’�tubes�give�desirably�better�electron/muon�and�electron/π0�separation�than�the�20’’�tubes�in�Super-K�

• Have�updated�to�simulation�using�WCSim�and�fiTQun�for�reconstruction

muon

electron

pion

1R�e-fit�momentum

π0�mass

π0e

e μ

L(π0)�/�L(e)

L(e)�/�L(μ)

Page 17: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 17

Direct�Background�Measurement�

• Total�neutrino�and�intrinsic�νe�and�fluxes�are�nearly�identical�in�the�intermediate�and�far�detectors�

• Can�measure�the�intrinsic�+�NC�background�directly�in�the�intermediate�detector

Page 18: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 18

The�Double�νe/νμ�Cross-Section�Ratio

goes�roughly�as�whereNνμ

near

nearNνμ

Nνefar

Nνefar

σ�νμσ�νe

σ�νμ σ�νe

PRELIMINARY

Page 19: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 19

νe�Cross�Section�Measurement�

• 1.5×1021�POT�exposure�at�each�off-axis�position�

• 3500�candidate�events�

• 71%�signal�purity�

• Aiming�for�~3%�precision�on�νe/νμ�cross-section�ratio

• Beam�νe�fraction�increases�with�off-axis�angle

Page 20: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 20

Preliminary�Statistical/Systematic�Errors�

• Systematic�errors�on�the�νe/νμ�cross-section�ratio�estimated�under�the�following�assumptions:�

• T2K�flux�systematics�

• 5%�error�on�muon�and�NC�backgrounds�(can�be�constrained�by�control�samples)�

• 50%�error�on�NC1γ�background�

• 1%�error�on�the�ratio�of�the�signal�efficiencies�for�νe�and�νμ�candidates�

• Under�these�assumptions,�can�get�<5%�for�E<1GeV�

• To�achieve�3%:�

• improve�flux�ratio�uncertainty�

• higher�purity�selection

Page 21: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 21

Initial�Phase�Option�

• Recent�consideration�of�an�initial�phase�for�the�intermediate�detector�

• On�the�surface�at�the�280�m�near�detector�site�

• Off-axis�angle�is�~9-12�degrees�

• Interesting�physics�with�large�off-axis�angle�beam�

• Can�begin�operation�before�excavation�of�new�intermediate�detector�facility�(dominant�cost)

Page 22: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 22

Surface�Detector,�Further�Consideration�

• K2K�1�kiloton�detector�observed�low�energy�background�from�“sky-shine”�neutrinos�—�needs�investigation�for�surface�detector�at�J-PARC�

• Surface�location�allows�for�initial�operation�of�the�water�Cherenkov�detector�in�combination�with�a�Baby-MIND�

• Have�started�investigation�of�available�space�at�the�280�m�site

Page 23: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 23

Proposed�ND280�Tracker�Upgrade

Current�detector Proposed�Upgrade

just�a�sketchThe�effect�of�this�new�configuration�on�the�oscillation�fit�is�currently�being�studied

•By�extending�the�tracker�and�adding�“side-TPCs”�we�greatly�improve�acceptance�

•This�will�reduce�model�dependence�for�high-Q2�parts�of�phase�space�

•We�retain�two�targets�to�allow�water�minus�scintillator�subtraction�analyses

Page 24: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 24

•The�current�FGDs�have�9.6�mm�segmentation,�and�FGD2�has�40%�water�

•The�Wagasci�solution�has�5�cm�(considering�2.5�cm)�segmentation�with�80%�water

Proposed�Upgrade�to�the�ND280�Target�Detectors

•With�3D�targets,�we�can�reconstruct�short�

pion�and�2p2h�proton�tracks�more�efficiently

3mm

Page 25: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 25

Summary�

•An�intermediate�water�Cherenkov�detector�addresses�the�most�critical�systematic�errors�for�Hyper-K�

•Two�designs�have�been�proposed�(TITUS�and�nuPRISM)�

•Will�be�merged�into�a�single�design�that�is�off-axis�angle�spanning�with�Gd�loading�

•The�Hyper-K�and�T2K-II�programs�can�benefit�from�the�earliest�possible�construction�and�operation��

•Now�pursuing�an�initial�phase�on�the�surface�at�280�m�

•The�intermediate�detector�is�an�ideal�location�for�testing�and�long�term�operation�of�new�technologies�and�systems�that�will�be�deployed�in�Hyper-K�

•ND280�upgrades�to�improve�angular�acceptance�and�lower�thresholds�for�pions�and�protons�are�being�studied�for�T2K-II.�They�will�be�complementary�to�an�intermediate�water�Cherenkov.�

•I�have�focused�on�CPV;�please�consult�the�TITUS�and�nuPRISM�articles�on�the�arXiv�for�more�physics!�

Page 26: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

26Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016

backup�slides

Page 27: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 27

Current�Detector�Proposals�

arXiv:1606.08114�[physics.ins-det]

arXiv:1412.3086�[physics.ins-det]

Page 28: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 28

Previous�(Proposed)�Detectors�

K2K�1�kiloton�detector�

• 20�inch�diameter�PMTs�

• 40%�photo-coverage�

• Achieved�0.3%�mis-ID�rate�of�muons�as�electrons�

T2K�2km�detector�

• Proposed�for�T2K�

• Potential�site�at�1.8�km�(same�direction�as�Tochibora)�

• Improved�performance�with�smaller�(8�inch)�PMTs�(finer�granularity)

Page 29: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 29

Particle�Identification�in�NuPRISM

T�Yoshida

Page 30: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 30

• The�intermediate�detector�provides�an�ideal�location�for�testing�new�technologies�and�systems�that�will�be�deployed�in�Hyper-K�

• Multi-PMTs�are�being�developed�for�Hyper-K�

• A�version�for�the�intermediate�detector�is�being�developed�in�Canada�

• Testing�of�systems�required�to�achieve�~1%�detector�errors�

• Long-term�operation�of�in-water�electronics

NuPRISM�WC�Detector�R&D�

Page 31: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 31

Timeline�Discussion�

Page 32: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

32Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016

• TITUS�23-sector�sensitivity�

• 1.3�MW�beam�

• 1:3�POT�ratio�for�ν:ν ̅

Page 33: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 33

Event�Rates�in�Initial�Phase�

• Estimate�event�rates�for�300�ton�ID,�2×1021�POT

Page 34: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

34Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016

Page 35: Near Detectors for Hyper-Kamiokande and the T2K Upgrade

Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 35

Effect�of�TITUS�on�Event�Rate�Systematics

#�e-like�ringsν-mode ν-̅mode

3.93.75.65.2

4.03.5

7.46.9

No�ND ND280 TITUS No�ND ND280 TITUS

ND280�numbers�only�for�*rough�comparison*!�they�are�take�from�slide�3�

The�ND280�numbers�should�improve�in�the�Hyper-K�era

•N.B.�TITUS�sensitivities�use�a�simple�fast�reconstruction�algorithm.��Expect�significant�improvement�after�updating�to�fiTQun�reconstruction.

Preliminary%