Neutrino energy reconstruction in presence of missing energy - - PowerPoint PPT Presentation

ProtoDUNEs Science Workshop - Cern June 28th, 2016 Ornella Palamara Fermilab & Yale University*

*on leave of absence from INFN, Laboratori Nazionali del Gran Sasso, Italy

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Neutrino energy reconstruction in presence of missing energy

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

Outline

๏ LAr TPC enable the use different energy reconstruction methods

• In particular, in LAr TPC we can infer E𝜉 from what we observe

in the final state

๏ ArgoNeuT neutrino energy reconstruction method including

estimates of missing/invisible energy

๏ Improved neutrino energy reconstruction including the

measurement of neutrons

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

Neutrino Energy Reconstruction

๏ Accelerator Neutrino beams are not monochromatic but

distributed on broad band spectra

๏ Precise and unbiased neutrino energy reconstruction is

especially important for reducing systematics in precision neutrino oscillation experiments

• Systematic which create a bias in neutrino energy definition

could affect ability to measure oscillation parameters

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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𝜉 scattering - Nuclear Effects

๏ 𝜉 experiments use complex nuclei as neutrino target

Nuclear effects

๏ Significantly alter final state particle topology/kinematics. ๏ Due to Intra-nuclear re-scattering (FSI, processes like pion

absorption, charge exchange…) and effects of correlation between target nucleons, even a genuine QE interaction can often be accompanied by the ejection of additional nucleons, emission of many de-excitation γ's and sometimes by soft pions in the Final State.

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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LArTPC

LAr TPC detectors providing full 3D imaging, precise calorimetric energy reconstruction and efficient particle identification allow for Exclusive Topology recognition and Nuclear Effects exploration from detailed studies

• f the hadronic part of the final states

𝜈-+0p

𝜉 interaction vertex

ν beam!

2D views from the two wire planes

Low charge

m.i.p. highly ionizing

High charge

drift time wire number

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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LArTPC

𝜉 interaction vertex

ν beam!

2D views from the two wire planes

Low charge

m.i.p. highly ionizing

High charge

drift time wire number

𝜈-+1p Low proton energy threshold (21 MeV Kinetic energy - ArgoNeuT) Neutrino energy reconstruction from all final state particles

➩

LAr TPC detectors providing full 3D imaging, precise calorimetric energy reconstruction and efficient particle identification allow for Exclusive Topology recognition and Nuclear Effects exploration from detailed studies

• f the hadronic part of the final states

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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LArTPC

𝜉 interaction vertex

ν beam!

2D views from the two wire planes

Low charge

m.i.p. highly ionizing

High charge

drift time wire number

multi-p accompanying the leading muon

𝜈-+2p Low proton energy threshold (21 MeV Kinetic energy - ArgoNeuT) Neutrino energy reconstruction from all final state particles

➩

LAr TPC detectors providing full 3D imaging, precise calorimetric energy reconstruction and efficient particle identification allow for Exclusive Topology recognition and Nuclear Effects exploration from detailed studies

• f the hadronic part of the final states

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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ν interaction vertex!

proton pion

Reconstructing E𝜉: Invisible Energy

๏ Reconstruct the energy of the incoming neutrino without knowing: ๏ the initial state of the target (need model - particularly important

at low energies)

๏ if all final state particles are observable. Initial correlations and

final state interaction affect the resolution

๏ We know the neutrino direction, so we can determine the

missing transverse momentum

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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Reconstructing E𝜉: Invisible Energy

ν interaction vertex!

proton pion neutron

E𝜉= deposited energy+invisible energy (from undetected particles, separation/excitation energy - for GeV neutrino events could ~10-20% of the total neutrino energy)

Few events with n p in ArgoNeuT (small LAr volume)

→

๏ We need to fully reconstruct the final state ๏ If particles are missed, then the neutrino energy is incorrectly

reconstructed

๏ The missing hadronic energy is mostly responsible for the missing

visible energy

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

Neutrino Energy Reconstruction in LArTPC

LArTPC enable the use of multiple neutrino energy reconstruction methods

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Eν = Eµ + X Tpi + TX + Emiss

Sensitive to invisible energy Complication: Nuclear Effects Includes estimate of (part of the) invisible energy

• Phys. Rev. D 90, 012008 (2014)

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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Neutrino Energy Reconstruction (CC 0 pion events)

TX=recoil energy of the residual nuclear system X [undetectable]. A lower bound is

estimated from the measured missing transverse momentum [we have no access to the longitudinal component of the missing momentum]:

Emiss=missing energy [nucleon separation energy from Ar nucleus + excitation energy of

residual nucleus (estimated by fixed average value, e.g. Emiss=30 MeV for 2p events)

Estimate of E𝜉 from the final state particle (muon AND protons) measured kinematics:

TX ≈ (pT

miss)2

2MX Eν = Eµ + X Tpi + TX + Emiss

• Phys. Rev. D 90, 012008 (2014)

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

An example: “Hammer” Events

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0.5 1 1.5 2 2.5 3

Mean [%]

rec

E

ν

• E

rec

E 30 − 20 − 10 − 10 20 30 QE Delta pp Mass pp Energy ArgoNeut (a)

[GeV]

rec

E 0.5 1 1.5 2 2.5 3 RMS [%]

rec

E

ν

• E

rec

E 5 10 15 20 25 30 35 (c) production π

0.5 1 1.5 2 2.5 3 30 20 10 10 20 30

(b)

[GeV]

rec

E 0.5 1 1.5 2 2.5 3 5 10 15 20 25 30 35 (d) NN → N ∆

ArgoNeuT calorimetric & missing pT energy reconstruction

ArgoNeuT)

Collec-on)plane)

μ2)

Iden-fied)also) by)MINOS) beam) Two)protons) back2to2back) =)color)scales)with)energy)deposit)

p+) p+)

Wire%number% Dri+% ,me%

b-to-b proton events described by pion production and re-absorption model

L.B. Weinstein, O. Hen, E. Piasetzky, “Hammer events, neutrino energies, and nucleon-nucleon correlations”, arXiv:1604.02482

• Phys. Rev. D 90, 012008 (2014)

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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_

+

➩

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Neutrino Energy Reconstruction (CC 0 pion events)

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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Truth Reco

14%

µ+Np final state events anti-nu mode

GENIE

Eν=Eμ+∑Tp

Tp>21 MeV

<E𝜉>=3.6 GeV

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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Truth Reco

Eν=Eμ+∑Tp+∑Tn

Truth Reco

Tp>21 MeV no thr. on neutrons, perfect reconstruction

14% 3%

µ+Np final state events anti-nu mode

Including neutrons

GENIE

Eν=Eμ+∑Tp

Tp>21 MeV

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

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proton (from neutron-proton charge exchange ) proton (from neutron-proton charge exchange)

proton (from neutron neutron-proton charge exchange )

ν interaction vertex!

proton at the vertex: trk_length=2.91 cm, KE=39.5 MeV

Reconstruction of neutrons in LAr (via proton from neutron-proton charge exchange scattering)

Few events with n p in ArgoNeuT (LArIAT) (small LAr volume)

→

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

Neutron energy reconstruction

๏ “Detection” of neutrons and estimate of neutron

energy reconstruction in LAr

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๏ MC studies (neutron

containment*, fraction of neutron-proton charge exchange scattering, proton energy vs neutron energy…)

๏ Measurements in ProtoDUNE

(via protons from neutron- proton charge exchange )

pion pion proton (from neutron-proton charge exchange)

* see presentation on hadron containment by Pawel Guzowski

• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

Summary

๏ Thanks to the LArTPC technology we can rely of different

methods of neutrino energy reconstruction

๏ Missing transverse momentum can be used to improve the

accuracy of energy reconstruction (ArgoNeuT)

๏ ProtoDUNE will tell us if the measurement of neutrons can

further improve the neutrino energy reconstruction

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

Overflow

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• O. Palamara | ProtoDUNEs Science Workshop

Cern, June 28 2016

Low energy proton reconstruction

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ArgoNeuT proton threshold: 21 MeV Kinetic Energy

The$short$track$behaves$like$proton$ *$Kine4c$energy$vs$track$length$(data)$

• $NIST$predic4ons$

The$event$is$(CCQE)$1p$–$1$µ!

muon%

Short%(2%wires)%track%with%high%ioniza6on%% superimposed%to%the%muon%track%

Length=0.5 cm

Tp=22 3 MeV

±

Stopping tracks - Calorimetric reconstruction and PID

Kinetic Energy vs. track length

Contained proton

residual range (from the track stopping point)

stopping point

. data

dE/dx vs. residual range (contained protons)

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The energy loss as a function of distance from the end of the track is used as a powerful method for particle identification.

. proton NIST tables

* data

proton proton pion pion

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pion

proton pion

dE/dx vs. residual range Kinetic energy vs. track length

ν interaction vertex!

p/π± identification

ArgoNeuT pion reconstruction threshold: ~8 MeV Kinetic energy

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dEdx: 0.04231+0.0001783*(dEdx)^2 KE: 0.6064/sqrt(KE)

ArgoNeuT (4 mm wire pitch) Resolution in dE/dx and Kinetic Energy