Neutron-Argon Cross Section Between 100 and 800 MeV Scott Locke - - PowerPoint PPT Presentation

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Neutron-Argon Cross Section Between 100 and 800 MeV Scott Locke - - PowerPoint PPT Presentation

Mar 09, 2024 301 likes •552 views

First Measurement of the Neutron-Argon Cross Section Between 100 and 800 MeV Scott Locke (for the CAPTAIN Collaboration) University of California, Irvine 09/09/2019 TAUP 2019 DUNE and Liquid Argon (LAr) Experiments Many current and future

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SLIDE 1

First Measurement of the Neutron-Argon Cross Section Between 100 and 800 MeV

Scott Locke (for the CAPTAIN Collaboration) University of California, Irvine 09/09/2019 TAUP 2019

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SLIDE 2

DUNE and Liquid Argon (LAr) Experiments

  • Many current and future experiments look to use a LAr Time Projection

Chamber (TPC) for neutrino detection, given its many ideal properties

  • DUNE (Deep Underground Neutrino Experiment) is one of the future large-

scale experiments to help probe some of the unresolved neutrino questions

  • CP-violation, ν mass hierarchy (MH), other exotic phenomena

09/09/2019 Scott Locke- UC Irvine 2

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SLIDE 3

Detecting (Anti-) Neutrinos

  • DUNE looks to examine oscillation neutrinos starting

at ~500 MeV and up to ~10 GeV

  • Going through different energy ranges, different

modes of interactions dominate

  • Quasi-elastic
  • Resonant Production
  • Deep inelastic scattering
  • DUNE’s energy ranges covers all three charged

current interactions, posing issues for event reconstruction

  • Accurate energy reconstruction is needed
  • Small shift in neutrino energy → big changes in oscillation

probability

  • Many of these processes will have neutral particles in

the final state

  • These neutral particles carry away energy, leading to mis-

reconstructed energies of the events

  • How much we underestimate the missing energy

greatly affects the best fits for mixing parameters

09/09/2019 Scott Locke- UC Irvine 3

  • Phys. Rev. D 92, 091301 (2015)

Hadronic energy budget arXiv:1811.06159 30% to neutrons

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SLIDE 4

Implications of Neutrons on Energy Reconstruction

  • Neutrons are responsible for a significant amount the energy that escapes detection
  • Neutrons are a possible product in all three forms of charged current interactions to be

seen by LAr experiments

  • Anti-neutrinos and neutrinos produce different numbers of neutrons → impact on MH and δcp
  • Neutrons do not thermalize easily in LAr
  • Neutrons are not well contained, even in a large detector
  • Many of the models used to estimate missing energy, have large unconstrained

uncertainties

09/09/2019 Scott Locke- UC Irvine 4

Energy carried away by neutrons

Plots by J. Chaves

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SLIDE 5

Current Data for n on LAr

  • Not much data at DUNE energies, and existing data is from is from

R.R. Winters et al., Phys. Rev. C43, 492 (1991) – www.nndc.bnl.gov

09/09/2019 Scott Locke- UC Irvine 5

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SLIDE 6

mini-CAPTAIN at LANL

  • 400 kg instrumented hexagonal TPC
  • 32cm drift, 50 cm apothem
  • ~1000 channels, 3mm wire pitch, 3

signal planes (+ ground and grid plane)

  • Same cold electronics and electronics

chain as MicroBooNE

  • Photon detection system (PDS) for

Time of Flight (ToF) calculation

  • Run July 2017, at WNR at LANL
  • Results based on special low intensity

run

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Beam mini-CAPTAIN Y X

Walter Sondheim

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SLIDE 7

Basic Analysis Strategy

  • Find tracks in TPC in time with beam and in beam spot
  • Match tracks in TPC to hits in PDS
  • Use timing from PDS to determine neutron energy
  • For tracks in each kinetic energy bin, fit exponential as function of depth

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neutron flux neutron scatters proton tracks Neutron Flux depleted as function of depth

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SLIDE 8

PDS

  • Hamamatsu R8520-506 MOD
  • 1x1 in, 25% QE at LAr temperature,

special Bialkali LT

  • ~11 pe/MeV in Mini-CAPTAIN
  • 24 PMTs
  • 21 in actual operation
  • Calculate event time in TPC using light

collected by PDS

  • Charge drift is slow in the detector, use

photons from the event for time

  • Used for correction in Z position of event
  • Calculate neutron energy from ToF
  • PDS is triggered on RF signal, and PDS

can also self-trigger if enough light is seen by PMTs

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Bottom PDS Arrangement Top PDS arrangement PMT and base

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SLIDE 9

Energy and PDS Timing

  • Beam creates a trigger by interacting

with a coil to create RF pulse

  • TPC is triggered off this RF pulse
  • The RF pulse is composed of 625 μs

wide macropulse with 10 ms between macropulses

  • Macropulses have micropulses 200 μs

apart, normal beam running is 1.8 μs

  • Get ~1 neutron / 6 micropulses
  • Use RF timing and light emitted in TPC

to calculate ToF of neutrons, and making energy calculation

  • Make correction for micropulse in ToF

calculation

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200 μs

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SLIDE 10

TPC

  • 3 planes with ~350 wires each
  • X plane (collection) perpendicular to x-axis,

U and V planes 60° with respect to X plane

  • Triggered on RF with a 4.75 ms data

acquisition window

  • 1.85 ms pretrigger
  • 600 μs beam time
  • 2.3 ms post trigger
  • Use wire hits and time to reconstruct

tracks within the detector

  • Find 2D clusters in a single plane and build

3D tracks

  • Detector is slightly rotated with respect

to the beam line

  • Large windows outside beam window

used for calibration with cosmics

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Neutron event from low intensity run

proton candidate

cosmic Preliminary Beam Region preliminary

Beam Direction

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SLIDE 11

Hit-Finding Efficiency

  • Data is from cosmic runs
  • Hit finding inefficiency seen for

large wire numbers

  • Most likely from unresponsive

wires → only consider lower wire numbers

  • Higher wire numbers are upstream

with respect to the beam

  • Fiducial volume:
  • -400.6 mm < x < 4.6 mm
  • corrected z: -195mm < z < -145 mm
  • must be in the 27-mm wide beam

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Dead wires

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SLIDE 12

Cross section fit

  • For a given energy bin, the total cross

section is proportional to the coefficient of the neutron flux depletion rate for a given topology:

  • Exponential fits with binning based on

available statistics

  • Fits reasonable for given statistics
  • Systematic uncertainties:
  • Multi-track from more than 1 n interacting in

beam window

  • Impact on cross-section measurement 10%
  • Uncertainty in track reconstruction, bin

placement, track finding (all percent level)

09/09/2019 Scott Locke- UC Irvine 12

481-674 MeV x (mm) Beam

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SLIDE 13

Neutron Cross Sections

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  • Exponential fits with binning

based on available statistics

  • Fits reasonable for given

statistics

  • Cross section energy-

weighted average is: 0.91±0.10(stat)±0.09(sys) barns

  • Recently published results:

PRL 123, 042502 (2019)

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SLIDE 14

CAPTAIN Detector

  • Cryostat
  • Capacity: 10 tons
  • TPC
  • Hexagonal prism with 1m vertical

drift, 1m apothem, 2000 channels, 3mm pitch, 5 instrumented tons

  • Photon detection system
  • Laser calibration system
  • Same cold electronics and electronics

chain as MicroBooNE

09/09/2019 Scott Locke- UC Irvine 14

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SLIDE 15

CAPTAIN Physics Program

  • Low-energy neutrino physics related
  • Measure the neutrino CC and NC cross-sections on argon in the same energy

regime as supernova neutrinos

  • Measure the correlation between true neutrino energy and visible energy for

events of supernova-neutrino energies

  • Medium-energy neutrino physics related
  • Measure neutron interactions and event signatures (e.g. pion production) to

allow us to constrain number and energy of emitted neutrons in neutrino interactions (at DUNE, mean neutron K.E. from the LBNF beam ~ 400 MeV)

  • Measure higher-energy neutron-induced processes that could be backgrounds

to ne appearance e.g. 40Ar(n,p0)40Ar(*)

09/09/2019 Scott Locke- UC Irvine 15

Low-Energy Neutrino Beam Neutron Beam

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SLIDE 16

Summary

  • We have made the first neutron-argon cross section measurement

between 100 and 800 MeV

  • Cross section energy-weighted average is 0.91±0.10(stat)±0.09(sys) barns
  • More physics to support other LAr experiments and DUNE
  • neutron-argon interactions – First measured cross-section in this energy

regime, improve the measurement, exclusive channels

  • Integrate neutron ID and measurements into neutrino energy reconstruction

for DUNE and SBN

  • Moving forward, build CAPTAIN with pixelated readout
  • Deploy CAPTAIN

09/09/2019 Scott Locke- UC Irvine 16

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SLIDE 17

CAPTAIN Collaboration

  • Alabama: Ion Stancu
  • LBL: Craig Tull
  • Boston University: Christopher Grant
  • BNL: Hucheng Chen, Veljko Radeka, Craig

Thorn

  • UC Davis: Daine Danielson, Steven Gardiner,

Emilija Pantic, Robert Svoboda

  • UC Irvine: Jianming Bian, Scott Locke, Michael

Smy

  • UC Los Angeles: David Cline, Hanguo Wang
  • Hawaii: Jelena Maricic, Marc Rosen, Yujing

Sun

  • Houston: Lisa Whitehead
  • LANL: Elena Guardincerri, Nicholas Kamp,

David Lee, William Louis, Geoff Mills, Jacqueline Mirabal-Martinez, Jason Medina, John Ramsey, Keith Rielage, Constantine Sinnis, Walter Sondheim, Charles Taylor, Richard Van de Water

  • New Mexico: Michael Gold, Alexandre Mills,

Brad Philipbar

  • New Mexico State: Robert Cooper
  • University of Pennsylvania: Connor Callahan,

Jorge Chaves, Shannon Glavin, Avery Karlin, Christopher Mauger, Keith Wiley

  • Stony Brook: Neha Dokania, Clark McGrew,

Sergey Martynenko, Chiaki Yanagisawa

09/09/2019 Scott Locke- UC Irvine 17

Spokesperson: Christopher Mauger; Deputy Spokesperson: Clark McGrew

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SLIDE 18

18

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SLIDE 19

Backup

09/09/2019 Scott Locke- UC Irvine 19

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SLIDE 20

Cross Section Fit

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X position [mm] X position [mm] 199-296 MeV 100-199 MeV

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SLIDE 21

Cross Section Fit

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X position [mm] X position [mm] 369-481 MeV 296-369 MeV X position [mm] 674-900 MeV

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SLIDE 22

Flux Detectors and Strategy

  • For some measurements, an external

understanding of the neutron spectrum may be important

  • Fission chamber – useful for high neutron

fluxes (~10-5 interaction rate) – standard facility equipment

  • Scintillator detector – useful for low neutron

fluxes (~10-2 interaction rate) – deployed by CAPTAIN

  • Cross-calibrate at moderately high flux

09/09/2019 Scott Locke- UC Irvine 22

Wender et al. NIM A 336 (1993) 226-231

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SLIDE 23

23

Shutters upstream Fission chamber and scintillator Detector shown displaced from the beamline – it was in the beam during running