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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
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
???
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
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
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
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
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
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.
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.
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!
*
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
Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 12
The�NuPRISM�Detector
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)
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.�
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
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)
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
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
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
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
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)
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
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
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
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!�
26Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016
backup�slides
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]
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)
Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 29
Particle�Identification�in�NuPRISM
T�Yoshida
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�
Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016 31
Timeline�Discussion�
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 ̅
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
34Near�Detectors�for�Hyper-K�and�the�T2K�UpgradeNuFact�2016
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%