ProtoDUNE Pion Quasi-elastic scattering Aaron Higuera University of Houston
Outline 1. Physics motivation, why we want to this measure cross sections? There are several pion analyses underway, this is just meant to show the physics deliverables for a pion quasi-elastic scattering analysis… I don't plan to step on someone's toes 2
Introduction Neutrino CC quasi-elastic scattering • Early during this decade CC QE was used as a standard candle for neutrino experiments to measure the flux • Clean experimental signature • Easily kinematics if you assume a nucleon at rest, can reconstruct Ev and Q 2 only using lepton kinematics • It was assumed to be a very well understood process 3
Introduction Neutrino CC QE scattering • MiniBooNE puzzle PRD 81, 092005 (2010) Modern neutrino detectors are made of materials with heavy nuclei Nucleons in the nucleus are no free How the nucleus changes the cross-section? • Initial state nucleons have fermi momentum (RFG model take into account this) • Other nuclear effects Short range correlation, MEC, RPA, final state interaction, etc 4
Introduction Electron scattering RevModPhys 80,189 (2008) Clear signature of nuclear effects PRD 72 053005 (2005) • Clean experimental signature precise measurements of k( E,p) and k’(E ’,p’) 5
Introduction Electron scattering Electron-scattering experiments found that, approximately 20% of the time, electrons scattered from correlated pairs of nucleons instead of single nucleons R. Subedi et al. Science, 320(5882):1476–1478, 2008 R. Subedi et al. Science, 320(5882):1476–1478, 2008 6
Introduction Electron quasi-elastic scattering RevModPhys 80,189 (2008) Quasi-elastic scattering • The QE peak provides a direct measure of the average momentum of nucleons in nuclei and the with of the peak reflects internal motion of nucleons in the nucleus • However, the coupling of the electrons to nucleons is almost entirely electromagnetic, and hadrons probes can be complementary to explore the full picture • Clean experimental signature precise measurements of k( E,p) and k’(E ’,p’) 7
Introduction Pion quasi-elastic scattering Pion quasi-elastic scattering at 950 MeV/c with different nuclei 2 H, 6 Li, C, Ca, Zr and 208 Pb PRC 64, 034608 (2001), thesis here
Introduction There is great academic interest in quasi-elastic scattering and more measurements are always useful This new measurements can provide useful information for neutrino+ 40 Ar interactions
Pion Quasi-elastic Scattering As neutrino interactions have to deal with FSI, we have too When the pion interacts with a nucleon within the nucleus (GEANT cross sections) the particles at the interaction vertex can go under different scattering process, this is modeled in GEANT by the Bertini cascade model π + So lets use the outgoing particles as the π + physics observables n π + + 40 Ar —> π + ’ + X(Nucleons) where X can be any number of nucleons X>1 p 10
Pion Quasi-elastic Scattering Pion scattering: Elastic scattering Inelastic scattering ( QE, pion production, charged exchange, absorption, etc) For the scattering process where π + + 40 Ar —> π + + X(Nucleons) where X can be any number of nucleons X>1 0.8 0.8 fraction 0.7 0.7 0.6 0.6 0.5 0.5 0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 0 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 number of protons Number of neutrons Number of nucleons What fraction are due to multi-nucleon correlations? What fraction are due to Bertini cascade? 11
<latexit sha1_base64="DC5cz4+K3p5NWyde6m1dRTa/apU=">ACMHicbZDLSgMxFIYz9VbrbdSlm2BHEIQyM13oplB0ocsW7AU6tWTStA3NXJpkhDLMI7nxUXSjoIhbn8J0Ooi2/iHw851zSM7vhowKaZqvWm5ldW19I79Z2Nre2d3T9w+aIog4Jg0csIC3XSQIoz5pSCoZaYecIM9lpOWOr2b1j3hgb+rZyGpOuhoU8HFCOpUE+/NoxJLy4nsAIdMeEyrt/FdnKmJkUMnJDkxRxQk8MkQ/NJ2tTAyjpxfNkpkKLhsrM0WQqdbTn5x+gCOP+BIzJETHMkPZjRGXFDOSFJxIkBDhMRqSjrI+8ojoxunCTxRpA8HAVfXlzClvydi5Akx9VzV6SE5Eou1Gfyv1onk4KIbUz+MJPHx/KFBxKAM4Cw92KecYMmyiDMqforxCPEZYq4IKwVpcedk07ZJVLtl1u1i9zOLIgyNwDE6Bc5BFdyAGmgADB7AM3gD79qj9qJ9aJ/z1pyWzRyCP9K+vgFOMqV4</latexit> <latexit sha1_base64="PBdpjI2iYAUrKz9wC3b8H+VkcTo=">ACBHicbVC7TsMwFHXKq5RXgLGLRYPEQpWEARakChbGVqIPqQ2V4zqtVcJtoNUR1Y+BUWBhBi5SPY+BucNgO0HOlKR+fcq3v8WNGpbLtb6Owsrq2vlHcLG1t7+zumfsHLRklApMmjlgkOj6ShFOmoqRjqxICj0GWn74+vMbz8QIWnEb9UkJl6IhpwGFCOlpb5ZtqzGXepO4SU87YVIjfwgvZ9mimX1zYpdtWeAy8TJSQXkqPfNr94gwklIuMIMSdl17Fh5KRKYkampV4iSYzwGA1JV1OQiK9dPbEFB5rZQCDSOjiCs7U3xMpCqWchL7uzO6Ui14m/ud1ExVceCnlcaIx/NFQcKgimCWCBxQbBiE0QFlTfCvEICYSVzq2kQ3AWX14mLbfqnFXdhlupXeVxFEZHIET4IBzUAM3oA6aAINH8AxewZvxZLwY78bHvLVg5DOH4A+Mzx83ZJaN</latexit> <latexit sha1_base64="IRjtM18iQYhd3l0hf0RGWgrTNKg=">ACEXicbVC7TsMwFHV4lvIKMLJYNIguVEkZYEGqYGEsEn1IbVQ5rtNadZxgO0hVlF9g4VdYGECIlY2Nv8Fpg4CWI1k6Pude3XuPFzEqlW1/GguLS8srq4W14vrG5ta2ubPblGEsMGngkIWi7SFJGOWkoahipB0JgKPkZY3usz81h0Rkob8Ro0j4gZowKlPMVJa6ply+oGSA09P7lN4Tn8/ozS4x96ZFnFnlmyK/YEcJ4OSmBHPWe+dHthzgOCFeYISk7jh0pN0FCUcxIWuzGkQIj9CAdDTlKCDSTSYXpfBQK3oh0I/ruBE/d2RoEDKceDpymxLOetl4n9eJ1b+mZtQHsWKcDwd5McMqhBm8cA+FQrNtYEYUH1rhAPkUBY6RCzEJzZk+dJs1pxTirV62qpdpHUQD74ACUgQNOQ1cgTpoAzuwSN4Bi/Gg/FkvBpv09IFI+/ZA39gvH8BpvmcQ=</latexit> Pion Quasi-elastic Scattering 1 Fraction Approximated a third of the inelastic 0.8 scattering are QE events 0.6 0.4 0.2 0 0 200 400 600 800 1000 Pion Kinetic Energy (MeV) π + + 40 Ar —> π + ’ + X(Nucleons) where X can be any number of nucleons X>1 q = k − k 0 Q 2 = − q 2 p Q 2 + q 0 q 3 = q 0 = ω q 3 = q 12
Pion Quasi-elastic Scattering π + 40 Ar —> π ’ + X(Nucleons) where X can be any number of nucleons X>1 Kinematics distribution based on true information 2200 2000 Angle between the incoming 1800 1600 pion and the outgoing pion 1400 1200 is small (low Q 2 ) 1000 800 600 400 200 0 − 1 − 0.5 0 0.5 1 cos( θ ) q <350 MeV/c 350< q <450 MeV/c 650> q MeV/c 700 600 250 600 500 200 500 400 400 150 300 300 100 200 200 50 100 100 0 0 0 0 100 200 300 400 500 600 700 800 900 1000 0 100 200 300 400 500 600 700 800 900 1000 0 100 200 300 400 500 600 700 800 900 1000 Energy loss ω (MeV) Energy loss ω (MeV) Energy loss ω (MeV) 13
<latexit sha1_base64="MKPJv6vJFAPj873J7GDMg762fZ4=">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</latexit> Pion Quasi-elastic Scattering The QE peak provides a direct measure of the average momentum of nucleons in nuclei and the with of the peak reflects internal motion of nucleons in the nucleus 1 ⇣p ⌘ M ∗ 2 + ( q + k F ) 2 − M ∗ 2 + ( q − k F ) 2 p Γ F G = √ 2 Fitting the width (FWHM) we can extract the Fermi momentum 500 FWHM (MeV) 450 400 350 k F = 235 ± 8.63 MeV/c 300 250 200 150 100 50 0 200 300 400 500 600 700 800 900 1000 Momentum tranger (MeV/c) 14
<latexit sha1_base64="9TLRmQSLlu1RkDO+UsEDur3UnCI=">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</latexit> Pion Quasi-elastic Scattering How we measure the cross section? The thin slice method not applicable For given bin i ✓ d � − N bkgd · N data ◆ 1 1 1 i i = · · ( ∆ q ) i ( ∆ ! ) i dqd ! N tgt � beam ✏ i i Need to define a fiducial volume and calculated the number of targets 15
Comments There is great academic interest in quasi-elastic scattering and more measurements are always useful d σ / dqd ω , k F , quasi - elastic peak shift ( relative to H ), etc There are few challenges in terms of reconstruction How good we can measure the interaction vertex How good is our tracking reconstruction at small scattering angle? How good we can calculate pion energy? How good we can tag nucleons? 16
The End 17
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