CC Coherent and CC neutral pion production results from MINERvA Jos - PowerPoint PPT Presentation

1 CC Coherent and CC neutral pion production results from MINERvA José Palomino* On behalf of the MINER ν A collaboration Centro Brasileiro de Pesquisas Físicas, Brazil *Supported by University of Pittsburgh CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

2 Outline of Talk • CC π 0 inclusive and exclusive reconstruction. ν µ W N N* π 0 v µ µ - N • CC π + coherent production. W π + A A CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

3 CC π 0 Event Topology RES-CC π 0 MC Using vertex position given by Muon track to scan the γ s Neutrino coming from π 0 . Strips ECAL HCAL NUCLEAR Proton TARGET REGION Gamma Gamma MC Neutrino Gamma NUCLEAR ECAL HCAL Strips TARGET REGION Gamma Modules CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

4 CC π 0 reconstruction Data - MC Event Selection for Anti neutrino interactions: 1 muon track with Minos Match( select anti-muons) Hits to be reconstructed, must be inside 25ns respect to Vertex time. Muon vertex must be inside fiducial volume. Showers must be reconstructed by Hough Transform ( Energetic showers ) or Angle Scan ( low energy showers ) 2 EM showers ( shower vertex should be not close to muon vertex ) Energy in Nuclear Target Region < 20 MeV CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

Invariant Mass 5 Cuts: 1 muon track + 2 EM showers + Energy in Target Region< 20 MeV m �� " � 2 E � � E � � (1 ! cos � � � ). Background events could be Pion charge exchange in detector and wrong reconstruction. To reconstruct CCPi0 inclusive events, we will select events in certain mass range (70 - 200 MeV/c2). CC π 0 inclusive Purity (54%) Efficiency (4.2%) CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

Vertex Energy 6 Vertex Activity: Energy contained inside R = 90 mm To choose vertex energy cut, the purity must be at least 30% To reconstruct CCPi0 exclusive events, first we need to reduce all background events, we are using “Vertex Energy” CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

CC π 0 reconstruction 7 Data Gamma2 Muon ECAL HCAL NUCLEAR Neutrino TARGET REGION R Gamma1 meaning “granularity” Reconstructed info: Energy contained inside R = 90 mm Mass = 139.47 MeV/c^2 Vertex Activity = 128.37 MeV Gamma Energy 1 = 132.05 MeV Gamma Energy 2 = 127.40 MeV CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

CC π 0 reconstruction - exclusive 8 Data Gamma1 R Muon ECAL HCAL NUCLEAR Neutrino TARGET REGION Gamma2 Reconstructed info: Energy contained inside R = 90 mm Mass = 130.88 MeV/c^2 Vertex Activity = 0 MeV Gamma Energy 1 = 164.32 MeV Gamma Energy 2 = 155.12 MeV CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

Invariant Mass after vertex energy cut 9 To reconstruct CCPi0 exclusive events, we select events with: • vertex energy less than 13MeV • mass between 40 - 240 MeV/c2. CC π 0 exclusive Purity (67%) Efficiency (7%) CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

10 dEdx Michel Electrons MINERvA detector allow us identify Gammas and Electrons. dEdx tool is good for pid particles on EM showers. To remove Background, we can look at dEdx to isolate gammas. dEdx Gamma from Pi0 decay CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

11 Kinematics Plots CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

12 Inclusive Events Inclusive Events Inclusive Events Inclusive Events CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

13 Exclusive Events Exclusive Events Exclusive Events Exclusive Events CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

14 Cross Section U ij ð N j � B j Þ P Steps � @ � � j 1.- Background substraction � ¼ ; � � 2.- Unfold ( bayesian ) � n � i � i � x i @x � � i 3.- Efficiency correction CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

15 Inclusive Events Inclusive Events Area normalized!! CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

16 Exclusive Events Exclusive Events Area normalized!! CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

Charged Current Coherent Pion 17 Production details at Aaron Higuera poster “Charged Current Charged Pion and Charged Current Coherent Pion v µ µ - Production” The defining feature of the interaction is that the hadronic final state contains a single pion and a W residual nucleus is in its ground state. π + Coherent interactions have a great practical application to neutrino experiments because NC coherent pion production is part of the background A A to the v e appearance measurement. The cross sections are low and backgrounds (usually from resonance pion production processes) are large. Measurements have been made for CC, however recent measurements could not find evidence at the very lowest energies. NC coherent has only been estimated from the sum of signal plus background. CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12

18 Towards a Data-Driven Analysis According to Partially Conserved Axial vector Current models (PCAC) CC coherent pion production must be produced at very low Q 2 (Q 2 <m 2 π ) in order to be in the PCAC regime. MINERvA will take that assumption as a start point in its effort to isolate CC coherent pion production. This analysis requests two tracks coming out of a common vertex in the tracker and one of them identified as a muon using MINOS near detector (MINERvA muon spectrometer). A Q 2 < 0.2 (GeV/c) 2 cut emphasize small x for coherent pion production, since <E π > for coherent is larger than <E π > for resonances, a x < 0.2 cut enriches the coherent sample. 3 10 × 1.4 900 Events / 0.05 2 MINERvA Prelim inary MINERvA Prelim inary DATA Two tracks Events / 0.025 (GeV/c) 9.43e19 POT 9.43e19 POT 2 2 800 Q < 0.2 (GeV/c) DATA Two tracks Q 2 = 2 E ν ( E µ − P µ cos θ µ ) − m 2 1.2 2 2 Q > 0.2 (GeV/c) µ 700 1 E ν = E µ + E π 600 0.8 500 400 0.6 300 0.4 200 0.2 100 0 0 0 0.2 0.4 0.6 0.8 1 1.2 0 0.2 0.4 0.6 0.8 1 2 2 2 x = Q /2mE Q (GeV/c) CC Coherent and CC neutral pion production results from MINERvA José Palomino � Thursday, October 25, 12

Towards a Data-Driven Analysis 19 3 10 × 2 MINERvA Prelim inary Events / 0.025 (GeV/c) 1.6 DATA Two tracks 9.43e19 POT The 4-momentum transfer to the nucleus |t| 2 2 Q < 0.2 (GeV/c) & x< 0.2 1.4 = (q-p π ) 2 must be small by definition. 1.2 1 By requiring kinematic cuts (Q 2 < 0.2 (GeV/ c) 2 and x < 0.2 ) MINERvA is able to isolate 0.8 CC Coherent candidates. 0.6 0.4 0.2 Charged Current 0 0 0.2 0.4 0.6 0.8 1 Coherent Pion Production Candidate 2 2 |t| = (q-p ) (GeV/c) � Data Run 2019 Subrun 5 Gate 339 E v = 6.51 GeV Strip Number E π = 2.37 GeV Q 2 = 0.038 (GeV/c) 2 |t| = 0.001(GeV/c) 2 x = 0.008 Module x view(from above) CC Coherent and CC neutral pion production results from MINERvA José Palomino Thursday, October 25, 12