Antiproton Annihilation on Argon Nuclei in LArIAT William Foreman, - - PowerPoint PPT Presentation

▶

Apr 11, 2024 124 likes •348 views

Antiproton Annihilation on Argon Nuclei in LArIAT William Foreman, University of Chicago On Behalf of the LArIAT Collaboration DPF 2017 Fermilab Wednesday, August 2, 2017 Motivation: Neutron-Antineutron Oscillation Feature of many BSM

SLIDE 1

Antiproton Annihilation on Argon Nuclei in LArIAT

William Foreman, University of Chicago On Behalf of the LArIAT Collaboration DPF 2017 – Fermilab Wednesday, August 2, 2017

SLIDE 2

Motivation: Neutron-Antineutron Oscillation

§ Feature of many BSM theories § For bound neutrons, signature is decay products from subsequent annihilation of oscillated neutron with a neighboring nucleon

2 Aug 2017 2

arXiv:1109.4227, Super-K Neutron-Antineutron Oscillation Search (2015)

τbound = R · τ 2

free

W. Foreman (UChicago), DPF 2017

SLIDE 3

Search for n-nbar in a LArTPC

§ Star-like topology & final state energy (Ef ~ 2mpc2 ) distinguishes from primary background

2 Aug 2017 3

Simulated n-nbar event in DUNE

J. Hewes, DUNE Collab. Mtg 2017
G. Karagiorgi,

DUNE Collab. Mtg 2017

§ DUNE expected to set τ (free) limit of ~1.7×109 s at 90% CL

ver 10yrs, a x5 improvement
n existing limit by Super-K of

2.7×108 s  See poster by Georgia Karagiorgi, and talk on 8/3 by Joshua Barrow!

W. Foreman (UChicago), DPF 2017

SLIDE 4

Antiproton Annihilation

2 Aug 2017 4

W. Foreman (UChicago), DPF 2017

Annihilation star first

bserved in photographic

emulsion experiment in 1955 at UC Berkeley

(Chamberlain, Segrè, Wiegand, Ypsilantis, Goldhaber)

pbar

SLIDE 5

Antiproton Annihilation

2 Aug 2017 5

W. Foreman (UChicago), DPF 2017

Mixed reviews in the press… “New Atom Particle Found; Termed a Negative Proton” New York Times “Grim New Find at UC.” Berkeley Gazette

pbar

Annihilation star first

bserved in photographic

emulsion experiment in 1955 at UC Berkeley

(Chamberlain, Segrè, Wiegand, Ypsilantis, Goldhaber)

SLIDE 6

Antiprotons in LArIAT

2 Aug 2017 6

W. Foreman (UChicago), DPF 2017

LArIAT Preliminary Lariat Negative Beamline Composition (MC + Data)

100A, 64 GeV pions

§ Antiproton annihilation at rest is our best proxy to n-nbar signals in data § LArIAT produces some pbars in our tertiary beamline (~0.007%!), which can stop and annihilate with surface Ar nucleons § A sample of pbar-Ar events in LArAT will:

§ Provide a test-bed for n-nbar reco algs over LArTPC data § Help constrain nuclear models used to simulate n- nbar final states

Data π- (48.4%) p- (0.007%) e- (40.9%) μ- (2.2%) K- (0.035%)

SLIDE 7

Selecting Antiprotons in the LArIAT Beamline

2 Aug 2017

W. Foreman (UChicago), DPF 2017

SLIDE 8

Beamline Mass Calibration with Protons

2 Aug 2017 8

W. Foreman (UChicago), DPF 2017

p+ d K+ e+ µ+ π+

Wire chamber track momentum [MeV/c] Time of flight [ns] Reconstructed beamline mass [MeV/c2] Events

e,μ,π K p d

p/pbar selection region:  750-1150 MeV/c2

LArIAT Run II Pos Tertiary Beam Entries: 262776

Preliminary

LArIAT Run II Pos Tertiary Beam Entries: 262776

Preliminary

SLIDE 9

Looking for Antiprotons in Negative Beam

2 Aug 2017 9

W. Foreman (UChicago), DPF 2017

Wire chamber track momentum [MeV/c] Time of flight [ns]

LArIAT Run II Neg Tertiary Beam Entries: 724019

Preliminary

Wire chamber track momentum [MeV/c]

LArIAT Run II Neg Tertiary Beam Proton Mass Cut Entries: 1532

All Run II negative beam data Selecting events in proton mass range

Preliminary

SLIDE 10

Wire Chamber Track Matching

2 Aug 2017 10

Wire chambers TPC

W. Foreman (UChicago), DPF 2017

LArIAT Run II Proton candidates

Preliminary

SLIDE 11

Wire Chamber Track Matching

2 Aug 2017 11

Wire chambers TPC

W. Foreman (UChicago), DPF 2017

LArIAT Run II Proton candidates

First ~5cm

Preliminary Preliminary

SLIDE 12

Wire Chamber Track Matching

2 Aug 2017 12

§ Good matching seen in proton sample § Currently optimizing selection cuts

W. Foreman (UChicago), DPF 2017

LArIAT Run II Pos Beam Proton candidates Preliminary

χ2/NDF = 1.47 N = 2062(46) μ = 1.46(1) σ = 0.89(2) C = 324(51)

LArIAT Run II Pos Beam Proton candidates Preliminary

Peak: 3.125 Mean: 11.44

Std. dev: 10.84

LArIAT Run II Pos Beam Proton candidates Preliminary

χ2/NDF = 0.93 N = 1351(17) μ = -0.0552(9) σ = 1.319(24) C = 326(18)

SLIDE 13

Event Selection Breakdown

2 Aug 2017 13

Event cuts Run 1 Neg Run 2 Neg Run 3 Neg

Total events 430,792 5,330,568 1,442,706 Beam event w/ TPC info

1.2s < T < 5.5s RawDigits size > 0

81,103 1,518,837 725,503 1 TOF & 1 Pz

15ns < TOF < 75ns 200 MeV/c < Pz < 1400 MeV/c

36,692 724,019 378,232 Proton mass cut

700-1300 MeV/c2

273 1,532 523 Identifiable pbar events (by eye) ~2 ~50 ~50 Golden stopping pbar events (by eye) ~1 ~15 ~15 WC-to-TPC match

α < 20 deg

3cm < dx < 6cm
6cm < dy < 6cm

Reject thru-going MaxMatched = 3

These by-eye steps to be replaced by WC-to-TPC matching, etc…

W. Foreman (UChicago), DPF 2017

SLIDE 14

Antiproton Candidate Event Examples

2 Aug 2017 14

Annihilation in-flight Annihilation at rest

LArIAT Raw Wire Data Collection Plane LArIAT Raw Wire Data Collection Plane Induction Plane Induction Plane

W. Foreman (UChicago), DPF 2017

SLIDE 15

A Few More…

2 Aug 2017 15

LArIAT: Raw Wire Data Collection Plane Induction Plane

W. Foreman (UChicago), DPF 2017

LArIAT: Raw Wire Data Collection Plane Induction Plane LArIAT: Raw Wire Data Collection Plane Induction Plane LArIAT: Raw Wire Data Collection Plane Induction Plane LArIAT: Raw Wire Data Collection Plane Induction Plane LArIAT: Raw Wire Data Collection Plane Induction Plane

SLIDE 16

Next steps

Stage 1: Event Selection

Ø Beam mass cut (done) Ø WC track matching (in prog.) Ø dE/dx

Stage 2: Energy at annihilation Stage 3:   Final state reconstruction

2 Aug 2017 16

Sum up visible energy along track

Anticipated results: § Charged pion multiplicity § MIP vs. EM-like ratio of deposition § Visible final-state energy

LArIAT Data 2D Reco

W. Foreman (UChicago), DPF 2017

SLIDE 17

Take-Aways § LArIAT has observed ~O(100) antiproton annihilations in LAr for the first time!

§ ~30 of these come to rest before annihilating

§ Now beginning work on reconstructing these events in the TPC – stay tuned!

2 Aug 2017 17

W. Foreman (UChicago), DPF 2017

SLIDE 18

Thanks!

2 Aug 2017 18

W. Foreman (UChicago), DPF 2017

SLIDE 19

Backup

2 Aug 2017 19

W. Foreman (UChicago), DPF 2017

SLIDE 20

Anticipated deliverables

2 Aug 2017 20

q Charged pion multiplicities q Neutral pion multiplicities

Ø challenging due to topology of π0 à 2γ showers

q Total visible energy

Ø MIP-like vs. EM-like total deposition

Num. of primary particles

Event Energy Event Momentum

MC Truth n-nbar topology in 40Ar

J. Hewes, G. Karagiorgi, K.

Terao @ DUNE Collab Mtg ‘17

W. Foreman (UChicago), DPF 2017

SLIDE 21

2 Aug 2017

W. Foreman (UChicago), DPF 2017

arXiv:1109.4227, Super-K Neutron-Antineutron Oscillation Search (2015)

Systematic Uncertainty Budget in Signal Efficiency in Super-Kamiokande N-Nbar Search

SLIDE 22

Beamline Selection Plots (Neg Beam)

2 Aug 2017

W. Foreman (UChicago), DPF 2017

Antiproton Annihilation on Argon Nuclei in LArIAT

William Foreman, University of Chicago On Behalf of the LArIAT Collaboration DPF 2017 – Fermilab Wednesday, August 2, 2017

Motivation: Neutron-Antineutron Oscillation

§ Feature of many BSM theories § For bound neutrons, signature is decay products from subsequent annihilation of oscillated neutron with a neighboring nucleon

τbound = R · τ 2

free

Search for n-nbar in a LArTPC

§ Star-like topology & final state energy (Ef ~ 2mpc2 ) distinguishes from primary background

§ DUNE expected to set τ (free) limit of ~1.7×109 s at 90% CL

2.7×108 s See poster by Georgia Karagiorgi, and talk on 8/3 by Joshua Barrow!

Antiproton Annihilation

Annihilation star first

emulsion experiment in 1955 at UC Berkeley

pbar

Antiproton Annihilation

Mixed reviews in the press… “New Atom Particle Found; Termed a Negative Proton” New York Times “Grim New Find at UC.” Berkeley Gazette

pbar

Annihilation star first

emulsion experiment in 1955 at UC Berkeley

Antiprotons in LArIAT

LArIAT Preliminary Lariat Negative Beamline Composition (MC + Data)

§ Antiproton annihilation at rest is our best proxy to n-nbar signals in data § LArIAT produces some pbars in our tertiary beamline (~0.007%!), which can stop and annihilate with surface Ar nucleons § A sample of pbar-Ar events in LArAT will:

Selecting Antiprotons in the LArIAT Beamline

Beamline Mass Calibration with Protons

p+ d K+ e+ µ+ π+

e,μ,π K p d

Preliminary

Preliminary

Looking for Antiprotons in Negative Beam

Preliminary

All Run II negative beam data Selecting events in proton mass range

Preliminary

Wire Chamber Track Matching

Wire chambers TPC

Wire Chamber Track Matching

Wire chambers TPC

First ~5cm

Wire Chamber Track Matching

§ Good matching seen in proton sample § Currently optimizing selection cuts

Event Selection Breakdown

Event cuts Run 1 Neg Run 2 Neg Run 3 Neg

Antiproton Candidate Event Examples

Annihilation in-flight Annihilation at rest

A Few More…

Next steps

Stage 1: Event Selection

Stage 2: Energy at annihilation Stage 3: Final state reconstruction

Anticipated results: § Charged pion multiplicity § MIP vs. EM-like ratio of deposition § Visible final-state energy

Take-Aways § LArIAT has observed ~O(100) antiproton annihilations in LAr for the first time!

§ ~30 of these come to rest before annihilating

§ Now beginning work on reconstructing these events in the TPC – stay tuned!

Thanks!

Backup

Anticipated deliverables

q Charged pion multiplicities q Neutral pion multiplicities

Ø challenging due to topology of π0 à 2γ showers

q Total visible energy

Ø MIP-like vs. EM-like total deposition

Systematic Uncertainty Budget in Signal Efficiency in Super-Kamiokande N-Nbar Search

Beamline Selection Plots (Neg Beam)

Run I Run II Run IIA

2.7×108 s  See poster by Georgia Karagiorgi, and talk on 8/3 by Joshua Barrow!

Stage 2: Energy at annihilation Stage 3:   Final state reconstruction