protodune-sp proton analysis - cern

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ProtoDUNE-SP Proton Analysis

Heng-Ye LiaoOn behalf of the DUNE CollaborationDPF 2019 NortheasternJuly 29, 2019

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Introduction• Protons are one of the final state particles in the neutrino charge current quasi-elastic

(CCQE) interaction. → Important for reconstructing the neutrino total energy in the interactions→ Must require precise cross section measurements

• Liquid argon TPC (LArTPC) has high resolution tracking and calorimetry. → Allow us to study neutrino-nucleus interactions in great detail

• ProtoDUNE-SP experiment→ Understand the detector responses of different particles interacting in a LArTPC→ Prototype detector that form the building blocks for DUNE

CCQEProtoDUNE-SP LArTPC

6 m

7 m

3.6 m

3.6 m

e- or μ-

n p

W

Particlebeam


*Pandora reconstruction algorithms: “The Pandora multi-algorithm approach to automated pattern recognition of cosmic-ray muon and neutrino events in the MicroBooNE detector”, Eur.Phys.J. C78 (2018) no.1, 82

• Detector response of protons in a LArTPC- Selection of beam protons, event reconstruction & energy calibration

• Sample for analysis: 1 GeV/c proton data, 6.6K tracks • Proton event selection

- Beam proton selection: Use the info from TOF & Cherenkov counters- After entering TPC: Track reconstruction using Pandora* recognition algorithms

Pandora Event Display (Data)

Proton Event Selection Blue: Cosmic Ray ParticlesPurple: Beam ParticleRed: Trigger


Proton Classification (Data)

Stopping Protons

0.69 1.05

Cut to select stopping protons

“Interacting” Protons

● Classification of 1 GeV/c proton events-Convert beam proton momentum to its CSDA range-Use the ratio cut (track length/CSDA range) to select stopping/interacting protons

• Stopping protons: used for calorimetry study/Particle ID• Interacting protons: for proton-Ar cross-section study

Stopping Proton

Interacting Proton

Peak position ≠ 11. Energy loss2. Space charge effect (SCE)

Wire Number

Tim

e t

icks

Wire Number

Tim

e t

icks

Collection View

Collection View

Track length:79.3 cm

Track length:36.7 cm

Beam Direction

ProtoDUNE-SP Preliminary

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X-position [cm]

Start/end points of cathode-crossing muon tracksStart/end points of cathode-crossing muon tracks

• Space charge effect (SCE): A build up of slow moving ions distributed over a region of TPC which distorts the E-field

• Ionization drift path being affected by SCE• Impact on reconstructed proton tracks

- Position / Calorimetry information (dQ/dx)

APA

Y-p

ositi

on [c

m]

*Integrate all the z-positions, ~240K tracks


CPA

Spatial distorations > 30 cm !

Space Charge Effect

CPA APAX

Y

Z

APABottom

Top

Dow

nstr

eam

Ups

trea

m

Beam


SCE Map

6

• Use through-going anode-/cathode-piercing muons to measure spatial offsets(Muons should cause straight tracks Curvature due to space charge effect)⇒

• Measure spatial distortion at TPC faces• Spatial distortion map

- Scale simulated 3D spatial distortion map with data/MC scale factors (SF) at TPC faces- Linearly interpolate SFs across TPC bulk- Spatial distortion drift velocity E-field map⇒ ⇒

True track

Measured track

3D maps in TPC bulk

(Curvature of track due to SCE)

2D maps at TPC Faces


SCE Correction

7

• Calorimetry information (dQ/dx or dE/dx) is affected by both spatial andE-field distortions

• Apply corrections of both spatial & E-field distortions derived from data-driven calibration

- - True Track– Measured Track

Spatial CorrectionSpatial Correction Calorimetry CorrectionCalorimetry Correction

(Curvature of track due to SCE)

Impacted by SCE viaspatial distortions

Impacted by SCE viaE-field distortions


Calibration – dQ/dx Correction

8

● Calibration scheme based on the over-all correction• dQ/dx Correction (non-uniform dQ/dx ⇒ uniform dQ/dx)

- Apply SCE correction - Use TPC crossing muon tracks for the correction - Correct non-uniform dQ/dx distribution caused by SCE and attenuation

Median dQ/dx before correction (Beam Side)

Low dQ/dx due to the grounded electron diverters

*Voxel size: 5 cm x 5 cm

Side View of ProtoDUNE-SP Detector


APA3 APA2 APA1


Calibration

9

• Select stopping muons for calibration • dQ/dx [ADC/cm] dE/dx [MeV/cm]⇒

- Tune calorimetry constant hence calibrated dE/dx matches expectation (modified box model*)

• Good agreement between data and MC for the most probable values

MIP region for calibration

Data: Stopping Muons

MC: Stopping Muons

*Reference: “A study of electron recombination using highly ionizing particles in the ArgoNeuT Liquid Argon TPC” (https://arxiv.org/abs/1306.1712)

Expectation



Expectation

– Data– MC


MIP region for calibration


Proton dE/dx vs Residual Range


Expectation

Data

Before SCE Correction After SCE Correction

*Statistics: Data before SCE corr.:1835 /after SCE corr. (small data sample): 721 MC (before SCE corr.): 1221 / after SCE corr. (small data sample): 52


MC


ProtoDUNE-SP Preliminary ProtoDUNE-SP Preliminary

Expectation

Expectation

Expectation

• Good agreement between data (MC) and expectation after SCE correction!


Overall dE/dx Distributions

• Good agreement between data and MC• Improvement on dE/dx distribution after SCE correction




Particle Identification (Data)

12


proton

Muon

• Particle identification using a calorimetry based particle ID

• Excellent p/μ separation of ProtoDUNE-SP data!


Summary

13

• Beamline instrumentations provide accurate information on both the beam particle species and the momenta

• Proton track reconstruction using Pandora is working nicely• Calibration scheme based on the overall correction has

been developed→ Promising result after space charge correction and calibration

• Encouraging consistency between data and MC for the dE/dx distributions

• Clear separation between muon and proton of ProtoDUN-SP data• Measure of inclusive proton-Ar cross section in development


Backup

14


Modified Box Model

Wion

: 23.6 [eV/ion]

c:calibration const. [ADC/ion] (c~6.155x10-3 for data being used)

ε: 0.5 [kV/cm] ρ: 1.38 [g/cm3]

β: 0.212 [(keV/cm)(g/cm2)/MeV]

α: 0.93

Reference: “A study of electron recombination using highly ionizing particles in the ArgoNeuT Liquid Argon TPC” (https://arxiv.org/abs/1306.1712)

Parameters:

dE

dx = ExpW

ionβ

dQdx

c ρ ε- α

ρ

βε


Spatial Offsets in Data

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