Reconstruction of neutrino interactions in PEANUT G.D.L., Andrea Russo, Luca Scotto Lavina Naples University

Plan of the presentation Introduction Monte Carlo simulation of PEANUT Event generator DIS,QE and RES merging Event reconstruction Optimization of the selection Data analysis Results Conclusions

PEANUT detector BL033 Neutrino beam and Cosmic ray exposure BeamPositionStartEndDuration (day) NEUTRINO /10/20 16:252005/11/07 09: COSMIC RAYS2005/11/07 09:402005/11/07 11: (2h)

Monte Carlo simulation of PEANUT 5000 neutrino interaction simulated per each kind of scattering: DIS, QE and RES DIS W2 distributionQ2 distribution

RES QE W2 distribution Q2 distribution

Charged-particle multiplicity in  interactions DIS RESQE “True” charged multiplicity (at least one micro-track)

Monte Carlo simulation Estimate of the expected fractions of DIS, RES and QE scattering events in PEANUT GeV Interacting neutrino energy

The fractions of DIS, RES and QE events were estimated by folding the previous distributions with the NuMI energy spectrum No explicit information on the NuMI energy spectrum, so we used RES and QE interactions, since QE and RES cross sections slightly depend on the interacting neutrino energy RESQE Results: (64.4 ± 0.5(stat) ± 1.2(syst))% DIS (13.1 ± 0.3(stat) ± 0.3(syst))% RES (22.5 ± 0.4(stat) ± 0.6(syst))% QE Systematic error from the QE and RES comparison

MonteCarlo details Orfeo single brick simulation Grain distribution from data Micro-track position and angular smearing simulated Tracking efficiency as in data SFT simulation not included yet: as a first attempt we assume a constant track matching efficiency of 80%

A procedure to identify neutrino events optimized with the MC simulation At least two tracks reconstructed Topological cuts on reconstructed vertices: Impact Parameter, IP < 50 µm and track-vertex longitudinal distance,  z < 3000 µm All tracks downstream of the vertex At least one track confirmed by SFT detector  z-versus-IP bi-dimensional cut

IP 90 (m m) Multiple track events Efficiency on signal = (84 ± 2)% of vertices Background rejection = (61 ± 3)% Estimated using backward two-track vertices IP 90 defined as 90% upper bound on Impact Parameter Cut defined by the blue line provides:

Track made of at least 5 base-tracks The track with UP > 3 and DOWN < 4 The track confirmed by SFT detectors Single track events For example: this track (black line) has UP=4 and DOWN = 2

Efficiency of neutrino event reconstruction Total reconstruction efficiency (multiple & single track events) (54.3 ± 0.8)% DIS (50.4 ± 0.7)% QE (54.1 ± 1.7)% RES Accounting for the different fractions (64.4 ± 1.2(syst) ± 0.5(stat))% DIS (13.1 ± 0.3(syst) ± 0.3(stat))% RES (22.5 ± 0.6(syst) ± 0.4(stat))% QE Total reconstruction efficiency = (54.1 ± 0.7)%

Charged-particle multiplicity after event reconstruction

Data analysis

Scanning areas All 57 plates have been general scanned: 5.55 x 4.30 cm^2 = 23.9cm^2 General scanning mode Measured density of aligned base-tracks: 4 base-track / mm 2 (transportation order) 0.7 base-track / mm 2 (assembly order) 30 plates have been general scanned: 11.1 x 4.30 cm^2 = 47.8 cm^2

PEANUT emulsions Transportation order Beam exposure

s ~ 8 m m Track reconstruction s =13 mrad Micro-track angular resolution Position and angular resolution in the plate to plate alignment Consecutive base-track accuracy s ~ 5 mrad

s = 0.7 m m s = 3mrad Base-track resolution: spatial and angular difference between a base-track and the corresponding volume track

Density of aligned base-tracks ~ 4/ mm 2 Track reconstruction in transportation order

Characterization of the tracks in transportation order Due to low momentum protons (~100MeV) High ionizing power (at least 10 segments in the following plots) High tracking efficiency

Beam tracks at least 4 segments in the following plots NuMI beam peak (  x,  y ) ~ (-50,0) mrad MIP particles: ~ 24 Tracking efficiency Density of aligned base-tracks ~ 0.7 / mm 2

Emulsion-SFT matching yx txty  x = 1190  m  y = 1240  m  tx = 5 mrad  ty = 8 mrad

Impact parameter and  z distribution track to vertex longitudinal distance IP zz ~ 60% up to 10 µm

Neutrino event identification volume tracks reconstructed 4074 vertices reconstructed 1045 with all forward tracks 25 confirmed by SFT 7 pass the “  z versus IP” cut made of more than 4 base-tracks 144 confirmed by SFT 13 with UP > 3 Identification of 20 neutrino interactions in the fiducial volume Single track eventsMultiple track events MC Multiplicity

“High” multiplicity events not matching the SFT dz (  m)ip (  m) dz (  m)ip (  m) dz (  m)ip (  m) tx (mrad)ty (mrad) tx (mrad)ty (mrad) tx (mrad)ty (mrad)

“High” multiplicity events not matching the SFT dz (  m)ip (  m) dz (  m)ip (  m) tx (mrad)ty (mrad) tx (mrad)ty (mrad)

Expected number of events in the brick BeamBeginEndDuration (days) NEUTRINO2005/10/20 16:252005/11/07 09: COSMIC2005/11/07 09:402005/11/07 11: Neutrino interaction rate in an iron target exposed to NuMI in the near hall (2 * 10 5 ) / (year * ton) 37 ± 6 neutrino interactions expected in the analyzed volume N mes /  total = 37 ± 8 neutrino interactions estimated from the 20 observed events after efficiency correction This value (increased by 8%) accounts for the lead target

Conclusions A volume of 337 cm 3 (half brick volume) was general scanned in one PEANUT brick Detailed single brick Monte Carlo simulation of PEANUT used to define a procedure to identify neutrino interactions The reconstruction efficiency of neutrino events for this procedure has been evaluated with Monte Carlo 20 neutrino interactions have been identified in the volume After the efficiency correction, we estimate (37 ± 8) neutrino interactions happening in the volume Good agreement with the number of expected events (37 ± 6) computed from the flux Outlook Enlarge the statistics Include SFT simulation in Monte Carlo