Pion scattering with the Pion scattering with the LArIAT experiment - PowerPoint PPT Presentation

Pion scattering with the Pion scattering with the LArIAT experiment LArIAT experiment Justin Hugon (On behalf of the LArIAT experiment) Louisiana State University 1

Liquid Argon in a Test Beam (LArIAT) Liquid Argon in a Test Beam (LArIAT) LArIAT TPC LArIAT TPC 170 L 0.25 tons 40 cm 40 cm of LAr Beam Direction Beam Direction 47 cm 47 cm 90 cm 90 cm Drift Direction Drift Direction Reuse the ArgoNEUT TPC in a charged particle beam at Fermilab 2

Liquid Argon in a Test Beam (LArIAT) Liquid Argon in a Test Beam (LArIAT) Wi r e / a n o d e p l a n e s C a t h o d e p l a n e R e a d o u t A S I C s Changes from ArgoNEUT: ● New wireplanes ● Cold front-end electronics fom MicroBooNE 3

LArIAT Goals LArIAT Goals ● Physics Goals – Hadron-Ar interaction cross sections ● p +/- -Ar to support ν cross-sections ● K +/- - Ar, supporting nucleon decay ● Geant4 validation – e/ g shower identification capabilities – Anti-proton annihilation at rest ● Similar to BSM n-n oscillation signature – Particle sign determination in the absence of a magnetic field, utilizing topology ● e.g. decay vs capture ● R&D Goals – Ionization and scintillation light studies ● Charge deposited vs. light collected for stopping particles of known energy – Optimization of particle ID techniques – LArTPC event reconstruction ● Compare 3mm, 4mm, 5mm wire pitch 4

LArIAT Testbeam LArIAT Testbeam ● Fermilab’s main injector sends 120 GeV protons to the Fermilab test-beam facility (FTBF) ● FTBF creates a tunable secondary beam, 8 GeV to 80 GeV, directed toward the LArIAT experimental 5 hall

LArIAT Tertiary Beamline LArIAT Tertiary Beamline M u l t i - w i r e C u t a r g e t p ’ p r o p o r t i o n a l s c h a m b e r s M u o n ( 8 - 8 0 G e V ) ( M WP C s ) H a l o v e t o R a n g e S e c o n d a r y b e a m S t a c k T P C D i p o l e A e r o g e l M a g n e t s C e r e n k o v C o l l i m a t o r s M u o n C o u n t e r s P u n c h t h r o u g h T i m e o f F l i g h t V e t o ( T O F ) ● Secondary target further reduces beam energy ● Instrumented beamline identifies and characterizes particles 6

LArIAT Beamline: Wire Chambers LArIAT Beamline: Wire Chambers LArIAT Preliminary Wire chambers reconstruct the position and momentum of the particles in the beamline Wire chamber reconstructed 7 momentum compared to simulation

LArIAT Beamline: Time of Flight LArIAT Beamline: Time of Flight 2 scintillator counters w/ ~1ns sampling, provide the time of flight (TOF) 8

LArIAT Beamline Detectors LArIAT Beamline Detectors TOF vs reconstructed momentum LArIAT Preliminary Combining the momentum and TOF allows for p / m /e, K, proton separation Additionally, using the known masses of the K and proton we can constrain the momentum scale to 1.5% 9

Matching Beamline to the TPC Matching Beamline to the TPC ● We can take this track reconstructed in the beamline and extrapolate it to the LArTPC and look for a match – We match in both position (+/- 5cm about the mean) and angle (< 10 o ) 10 10

Calibrating our sample Calibrating our sample LArIAT Preliminary ● Using the first few centimeters of a matched track we can characterize the dE/dX response as a function of the track’s initial momentum in both data and simulation ● Calibrate detector response to follow Bethe-Block formula by selecting events with different particle type and momentum 11 ● Calibrate using pions; check on kaons/protons

Smearing Simulated Data Smearing Simulated Data LArIAT Preliminary ● Cosmic-ray muons provide Events / (0.1 MeV/cm) another calibration sample – Width of dE/dx distribution can be compared between data and simulation LArIAT Preliminary ● Additional 20% smearing makes the simulation match the data 12

Pion Event Selection Pion Event Selection ● Our MC allows us to LArIAT Preliminary estimate what our fractional beam composition and our selection efficiencies are for the various particle species 13

Pion Cross-Section Pion Cross-Section ● The total p – –Argon Cross-Section includes σ Total =σ elastic +σ inelastic +σ ch-exch +σ absorp. +σ p -production E l a s t i c S c a t t e r i n g C a n d i d a t e + LArIAT Data LArIAT Data C h a r g e E x c h a n g e C a n d i d a t e I n e l a s t i c S c a t t e r i n g C a n d i d a t e + + LArIAT Data LArIAT Data LArIAT Data π P r o d u c t i o n C a n d i d a t e A b s o r p t i o n C a n d i d a t e ( π - > 3 p ) + 14 LArIAT Data LArIAT Data

Pion Cross-Section Pion Cross-Section ● Backgrounds are: LArIAT Data Mu o n B a c k g r o u n d π D e c a y C a n d i d a t e π C a p t u r e C a n d i d a t e LArIAT Data LArIAT Data LArIAT Data Pion Interaction Type per Kinetic Energy Pion Interaction Fraction per Kinetic Energy LArIAT Simulation LArIAT Simulation Note: Pion decay backgrounds are small component which remain in our result. 15 Capture dominates the lowest energy bin and is thus excluded

Thin Slice TPC Method Thin Slice TPC Method ● Generally, the survival probability of a pion traveling through a thin slab of argon is given by: −σ n z P Survival = e Where σ TOT is the cross-section per nucleon, z is the depth of the slab, and n is the density ● The probability of the pion interacting is thus: P Interacting = 1 − P Survival where we measure the probability of interacting for that thin slab as the ratio of the number of interacting pions to the number of incident pions: N interacting −σ nz = P Interacting = 1 − e 16 N Incident

Thin Slice TPC Method Thin Slice TPC Method ● Thus you can extract the pion cross-section as a function of energy as P Interacting = 1 −( 1 −σ n δ z + ... ) N interacting σ( E )≈ 1 nz P Interacting = 1 nz N Incident Where n = r N A / A ● Using the granularity of the LArTPC, we can treat the wire-to-wire spacing as a series of “thin-slab” targets if we know the energy of the pion incident to that target 17

Pion Cross-Section Pion Cross-Section ● Now we have a matched WC track and TPC track ● We calculate the p -candidate's initial kinetic energy as KE i = √ p 2 + m p 2 − m p − E Flat we take into account energy loss due to material upstream of the TPC (argon, steel, beamline detectors, etc) ● We then follow p -candidate track treating each Analyze the reconstructed tracks point as a “thin slice” of argon which the pion is incident to at a known energy nSpts Interacting KE Interaction = KE i − ∑ dE / dX i × Pitch i i = 0 Kinetic Energy (MeV) Incident 18 Kinetic Energy (MeV)

Pion Cross-Section Pion Cross-Section nSpts Interacting KE Interaction = KE i − ∑ When you dE / dX i × Pitch i encounter the i = 0 interaction point you now fill the Kinetic Energy (MeV) interacting and Incident incident histogram for the energy the pion has at that point Kinetic Energy (MeV) Interacting You now repeat this process for your entire sample Kinetic Energy (MeV) Incident 19 We ignore other tracks in the event not matched to the Wire Chamber Track Kinetic Energy (MeV)

Pion Cross-Section Pion Cross-Section ● You now take the ratio of these two histograms to extract the cross-section Interacting N interacting σ( E )≈ 1 nz P Interacting = 1 nz N Incident Incident Where n = r N A / A 20

Pion Cross-Section Pion Cross-Section Systematics Considered Here dE/dX Calibration: 3% (previously was 5%) (previously was 5%) Energy Loss Prior to entering the TPC: 3.5% Through Going Muon Contamination: 3% 21 Wire Chamber Momentum Uncertainty: 3%

Toward Exclusive Pion Channels Toward Exclusive Pion Channels ● Working on absorption + charge exchange: p + Ar → 0π ± + X – Useful for modeling contamination of ν CC QE from CC RES where a π is absorbed in Signal Events: the interaction nucleus 0 Secondary π ± – Need to identify outgoing pions v. protons C h a r g e E x c h a n g e C a n d i d a t e Background Events: Contain Secondary π ± LArIAT Data A b s o r p t i o n C a n d i d a t e ( π - > 3 p ) LArIAT Data 22 LArIAT Data

Likelihood-Based Particle ID Likelihood-Based Particle ID ● Likelihood of dE/dx versus residual range of each track hit – Constructed from simulated tracks – Evaluate using likelihood-ratio of all hits on a track Proton Pion Likelihood Likelihood 23

Anti-proton Annihilation Anti-proton Annihilation LArIAT Data g g g g g g halo muon g g p-candidate multi-nucleon ● LArIAT has identified O (20) anti-proton annihilation at rest candidates – O (70) annihilation in flight p-candidate ● Similar to BSM n-n LArIAT Data oscillation signature Work ongoing to reconstruct these 24 – DUNE planning search final state topologies