1. Low-Energy -Nucleus Scattering Jorge G. Morfín Fermilab WIN’03 8 October 2003

2. n-Nucleus Scattering Experiments 2 Time Line of Neutrino Studies 1960’s - Have only low-energy ’s - Study properties of neutrinos - How many neutrinos are there?… 1970’s - Use low-energy neutrinos as a probe to study structure of the nucleon - structure of the weak current 1980’s - 1990’s - Increased  energy and more massive detectors yield higher statistics and expanded kinematic range for nucleon structure studies 1990’s - 2000’s - Study properties of neutrinos - need low-energy ’s for this study - How many neutrinos are there?

3. n-Nucleus Scattering Experiments 3 What’s covered by “low-energy  Nucleus interactions”  Cross sections of exclusive states.  Bridging the gap from resonance to DIS.  Nuclear Effects t x Bj -dependent nuclear effects (Shadowing, anti-shadowing, EMC-effect...) t Pauli suppression, t Nuclear Binding t Nuclear correlations, t Extended Fermi Gas model or Spectral Functions, t Hadron Formation Length and Nuclear transparency, t Final State Interactions.

4. n-Nucleus Scattering Experiments 4 Steps ( not necessarily time-ordered ) in Low Energy -Nucleus Interactions  Incoming neutrino imparts q (momentum and energy) via an IVB to a nucleus.  Depending on x, q: t The interaction proceeds under shadowing, anti-shadowing or EMC effect. t the IVB interacts with the entire nucleus, ≥ 1 nucleon or with one or more quarks.  For interactions with a nucleon, the target nucleon (off shell) carries initial p and E k within the nucleus.  The (excited) A-1 nucleus recoils with -p and proceeds to a ground state via  -emission or boil-off protons or other breakup mechanisms.  A hadronic state is created (quasi-elastic, resonance, continuum, DIS…). t Pauli Blocking influences final state nucleon momentum (quasi-elastic).  The produced hadronic state proceeds through the nucleus. t Nuclear transparency, formation zone, and nuclear densities influence final state interactions.  A visible final hadronic state and visible neutrino energy are recorded.

5. n-Nucleus Scattering Experiments 5 Why do we care about low energy phenomena?  E vis is not E - effect on the measurement of oscillation parameters  Understanding backgrounds to  ---> e  NC resonant 1  0 production (direct or through nuclear effects)  Coherent 1  0 production  Observed hadronic state (particle type and kinematics) not necessarily the produced state  (  ) interaction kinematics perturbed via nuclear effects t Quasi-elastic events lost or mimicked by resonance via nuclear effects

6. n-Nucleus Scattering Experiments 6 How Important are Low-energy Neutrinos? Seeing the “dip” in the oscillation probability is a goal of MINOS VERY Difficult at low  m 2. CC energy distributions have two important complications at low energy: Difference between E vis and E due to nuclear effects (particularly re-scattering, absorption). A required subtraction of NC events that fake low energy CC. In both cases MINOS, as well as all other oscillation experiments, will have to rely on MC - only as good as the input!.

7. n-Nucleus Scattering Experiments 7 State of our Knowledge for these Steps  The interaction proceeds under shadowing, anti-shadowing or EMC effect.  Can’t blindly use e/  - A results for - A since axial vector current participation t Evidence nuclear effects different - valence and sea quarks, theory hint of same for u & d t Use nuclear pdf’s (Kumano or Eskola et al).  For interactions with a nucleon, the target nucleon (off shell) carries initial p and E k within the nucleus. t Bodek-Ritchie extended Fermi-gas model invalid at high p F (NOMAD/CHORUS) t Use spectral functions (O. Benhar) - careful since some encompass “EMC-effect”  A hadronic state is created (quasi-elastic, resonance, continuum, DIS…). t Limited experimental data.  For decades only --> N * by Rein-Sehgal from 70’s, now Lee-Sato for +N -->  +  t From resonances to DIS: duality arguments and recent work by Bodek-Yang on low Q, high x pdfs  The produced hadronic state proceeds through the nucleus. t Major stage in the process. Introduce very significant changes in the number and identity of hadrons (pion absorption and charge exchange) and total visible energy t Dual-parton Model with Formation Zone Intranuclear Cascade and Nuclear Transparencies

8. n-Nucleus Scattering Experiments 8 Experimental Input - Make-up of  T at low energy

9. n-Nucleus Scattering Experiments 9 Just What Experimental Input is Available? Very complete and thoughtful analysis by: S. Zeller & E. Hawker and M. Sakuda D. Naples NuInt02 Sam Zeller NuInt02 Workshop on Neutrino-Nucleus Interactions in the Few GeV Region NuInt

10. n-Nucleus Scattering Experiments 10 Coherent Pion Production 00 NN P Z

11. n-Nucleus Scattering Experiments 11 Current/Future Experimental Investigations of these Topic  Fermilab Booster Neutrino Beam - 8 GeV Protons t MninBooNe Experiment t FINeSE Experiment  KEK Neutrino Beam - 12 GeV Protons t Original K2K Near Detectors t New SciBar Detector  Fermilab NuMI Beam - 120 GeV Protons t MINERvA Experiment

12. n-Nucleus Scattering Experiments 12 Fermilab Booster Neutrino Beam 8 GeV Protons MiniBooNe - H. Tanaka’s Presentation and discussions FINeSE - Fermilab Intense Neutrino Experiment

13. n-Nucleus Scattering Experiments 13 Energy Spectrum and Channels Covered Peak Down by 1/10

14. n-Nucleus Scattering Experiments 14 FINeSE Detector Submit Proposal 12/03, if approved (and find $) start data-taking mid-06

15. n-Nucleus Scattering Experiments 15 FINeSE Physics Goals  Measure contribution of strange quark to the spin of the proton -  s  Measure interaction cross-sections (40 % events QE)  Extract nucleon form factors

16. n-Nucleus Scattering Experiments 16 KEK Neutrino Beam Line 12 GeV Protons Peak Down by 1/10

17. n-Nucleus Scattering Experiments 17 K2K Original Front Detectors

18. n-Nucleus Scattering Experiments 18 Results in addition to yesterday’s 1  0

19. n-Nucleus Scattering Experiments 19 SciBar has been installed in summer 2003 Next Generation: New SciBar Detector

20. n-Nucleus Scattering Experiments 20 Large Volume: (300×300×166) cm 3 ~15tons 10 ton fiducial volume Fine segmentation: 2.5×1.3cm Particle ID: p/  : dE/dx  /  : range #channels : ~15,000 Proton Momentum: by dE/dx and the range The SciBar Detector Fully Active Statistics 45,000 events (12,000 QE) / 3 x 10 19 POT

21. n-Nucleus Scattering Experiments 21 SciBar Physics Motivation Precise measurements of the neutrino-nucleus cross section around ~1GeV energy region. ① CC Quasi-elastic scattering ( + n   + p) ① We will have a higher efficiency with a proton detection than other K2K Near detectors. ② CC-1  (resonant) production cross section. ( + n   + p) ① With the precise measurement, will also use this mode to reconstruct the neutrino energy with the charged  since it goes though the Delta resonance. ③ Deep inelastic scattering ( + n   + p  ) ① Which the Bodek and Yang modification is correct or not at the K2K energy? ④ Coherent Nuclear interaction (CC: + A   +A, NC: + A   +A) ① No measurement at this energy region so far. test theoretical models ② Measure both CC and NC coherent cross section. ⑤ Measure spectrum of e

22. n-Nucleus Scattering Experiments 22 MINER A (Main INjector ExpeRiment v-A) A High-Statistics Neutrino Scattering Experiment Using an On-Axis, Fine-grained Detector in the NuMI Beam Argonne - Athens - California/Irvine - Colorado - Dortmund - Duke - Fermilab - Hampton - I I T - INR/Moscow -James Madison - Jefferson Lab Minnesota - Pittsburgh - Rochester - Rutgers - South Carolina - Tufts 18 Groups: Red = HEP, Blue = NP, Green = Theorists only A Near Detector Hall Experiment

23. n-Nucleus Scattering Experiments 23 Fermilab NuMI Beamline “Zoom-lens”: Horn 1 fixed - target and Horn 2 moved NuMI: Neutrinos at Main Injector 120 GeV protons 1.9 second cycle time Single turn extraction (10  s) Beam: POT Late 2004

24. n-Nucleus Scattering Experiments 24 NuMI -energy Distributions and Event Rates in the Near Detector Hall  With 2.5 x 10 20 pot per year of NuMI running at start-up.  le-configuration: Events- (E  >0.35 GeV) E peak = 3.0 GeV, = 10.2 GeV, rate = 200 K events/ton - year.  me-configuration: Events- E peak = 7.0 GeV, = 8.5 GeV, rate = 675 K events/ton - year s-me rate = 540 K events/ton - year.  he-configuration: Events- E peak = 12.0 GeV, = 13.5 GeV, rate = 1575 K events/ton - year s-he rate = 1210 K events/ton - year. With E-907 at Fermilab to measure particle spectra from the NuMI target, expect to know neutrino flux to ≈ ± 3%.

25. n-Nucleus Scattering Experiments 25 Parasitic Running: Event Energy Distribution  MINOS oscillation experiment uses mainly le beam with shorter s-me and s-he runs for control and minimization of systematics.  An example of a running cycle would be: t 12 months le beam t 3 months s-me beam t 1 month s-he beam  Consider 2 such cycles (3 year run) with 2.5x10 20 protons/year: 860 K events/ton. = 10.5 GeV t DIS (W > 2 GeV, Q 2 > 1.0 GeV 2 ): 0.36 M events / ton t Quasi elastic: 0.14 M events / ton.  Resonance + “Transition”: 0.36 M events / ton - 1  production: 0.15 M events / ton. Peak Down by 1/10

26. n-Nucleus Scattering Experiments 26 MINER A Detector: Basic Conceptual Design - Coordinator: K. McFarland  Triangular ≈ (2-3 cm base x 1-2 cm height) scintillator (CH) strips with fiber readout. Fully Active ( int = 80 cm, X 0 = 44 cm) / alternate with C planes >   and nuclear tgt.  Favored Photo-sensor: MAPMT (M64 a la MINOS)  Example fid. vol: (r =.8m L = 1.5 m): 3 tons pure plastic or 5 tons with graphite R = 1.5 m - p:  =.45 GeV/c,  =.51, K =.86, P = 1.2 R =.75 m - p:  =.29 GeV/c,  =.32, K =.62, P =.93  Nuclear targets: of C, Fe and Pb.-  Surround fully active detector with em-calorimeter, hadron-calorimeter and magnetized  -id / spectrometer  Use MINOS near detector as forward  identifier / spectrometer.  Attempt to constrain detector size so can be moved to an off-axis position.

27. n-Nucleus Scattering Experiments 27 Basic Conceptual Design : ( A. Bodek, D. Casper and G. Tzanakos) Overall dimensions and relative volumes currently being determined X U V VUX EM Calorimeter: 2 mm = 1.5 mm Pb and two 0.25 mm stainless on each side Magentized Hadron Cal +  Id/spec. Coils - bottom sides only Active Scintillator / Graphite detector Downstream end: EM Calorimeter plus HadCal Fiducial Volume

28. n-Nucleus Scattering Experiments 28 Event rates (2.5 x 10 20 protons per year) MINOS Off-axisPrime User Prime User Parasitic Parasitic (3 years) (1 year, me- ) (1 year, he- ) (2 year, he - ) CH2.60 M2.10 M4.80 M 2.70 M C1.70 M1.40 M3.20 M 1.80 M Fe1.70 M1.40 M3.20 M 1.80 M Pb1.70 M1.40 M3.20 M 1.80 M LH 2 0.15 M 0.35 M 0.20 M LD 2 0.35 M 0.80 M 0.45 M Detector ( 3 ton CH, 2 ton A ): Event Rates; CC - E  > 0.35 GeV

29. n-Nucleus Scattering Experiments 29 Physics of the Proposal  Quasi-elastic Reaction - MINOS 3 year run, 3 ton fid. Vol - 420 K events  Precision measurement of  E ) and d  /dQ, constrain -beam systematics t Precision determination of F A t Study of nuclear effects and their A-dependence e.g. proton intra-nuclear rescattering  Resonance Production ( , N*..) Exclusive channels - 450 K 1-  events  Precision measurement of  and d  /dQ  for individual channels t Detailed comparison with dynamic models, comparison of electro- & photo production the resonance-DIS transition region -- duality  Study of nuclear effects and their A-dependence e.g. 1   2  3  final states  Nuclear Effects - > 1700 K events per nuclear target  Measure  and p multiplicities as a function of E and A : convolution of quark flavor- dependent nuclear effects and final-state intra-nuclear interactions t Measure NC/CC as a function of E H off different nuclei t Measure shadowing, anti-shadowing and EMC-effect as well as flavor-dependent nuclear effects and extract nuclear parton distributions

30. n-Nucleus Scattering Experiments 30 Physics of the Proposal - continued  Total Cross-section and Structure Functions - 1200 K transition, > 1000 K DIS t Precision measurement of low-energy total cross-section t Understand resonance-DIS transition region - duality studies with neutrinos t Detailed study of high-x Bj region: extract pdf’s and leading exponentials  Coherent Pion Production - 200 K plastic plus nuclear targets  Precision measurement of  for NC and CC channels t Measurement of A-dependence t Comparison with theoretical models models  MINER A and Oscillation Physics -  MINER A measurements enable greater precision in measure of  m, sin 2  23 in MINOS  MINER A measurements fundamental for  13 in MINOS and off-axis experiments  MINER A measurements as foundation for measurement of possible CP and CPT violations in the  sector

31. n-Nucleus Scattering Experiments 31 Physics of the Proposal - continued  Strange and Charm Particle Production -  Exclusive channel  E ) precision measurements - importance for nucleon decay background studies.  Hyperon Production yielding new measurements of CKM using t Exclusive charm production channels at charm threshold to constrain m c  Generalized Parton Distributions - t Provide unique combinations of GPDs, not accessible in electron scattering (e.g. C-odd, or valence-only GPDs), to map out a precise 3-dimensional image of the nucleon t Provide better constraints on nucleon (nuclear) GPDs, leading to a more definitive determination of the orbital angular momentum carried by quarks and gluons in the nucleon (nucleus) t provide constraints on axial form factors, including transition nucleon --> N* form factors

32. n-Nucleus Scattering Experiments 32 Summary Future of Low-Energy -Nucleus Scattering Studies Very Encouraging