1. Near Detector at a Neutrino Factory Chuzenji Lake, Nikko, Japan. 10 November 2005 Paul Soler University of Glasgow/RAL

2. 2 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 Contents 1.Physics motivation Neutrino Factory 1.1 Neutrino oscillations 1.2 Neutrino factory 1.3 Neutrino factory physics reach 2.Near Detector at a Neutrino Factory 2.1 Flux normalization 2.2 Cross-sections 2.3 Parton Distribution Functions 2.4 Charm production 2.5 Sin 2  w 3.Near detector requirements 4.NOMAD-STAR, an R&D prototype 5.Near detector ideas

3. 3 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 1.1 Neutrino Oscillations o Neutrino oscillations well established o Neutrino flavour mixing: Pontecorvo-Maki-Nakagawa- Sakata (PMNS) matrix o Atmospheric neutrinos: SuperKamiokande

4. 4 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 1. Neutrino Oscillations o Solar neutrinos (SuperKamiokande, Sudbury, Chlorine and Gallium Experiments) and KamLand reactor experiment: SudburyKamLand

5. 5 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 1. Neutrino Oscillation fits o Consistent picture emerging  Global fit provides  23,  12,  m 12 2 and  m 23 2   13 not known, mass hierarchy not known,CP violation phase  not known.

6. 6 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 1.2 Neutrino Factory o Matter-antimatter asymmetry of the universe: baryogenesis (CP violation in quark sector), leptogenesis (CP violation in lepton sector) o Conceptual design: neutrinos produced from muon decay in storage ring. Rate calculable by kinematics of decay (Michel spectrum)  Neutrino factory: very long baseline oscillation experiments to measure  13, mass hierarchy and leptonic CP violation

7. 7 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 1.3 Neutrino Factory physics reach o Far detector (3000-7000 km) can search for “wrong-sign” muons in appearance mode (for example, Large Magnetic Detector) o Background: charm production, charge misidentification.  Q t = P  sin 2  cut eliminates backg at 10 -6 Large Magnetic Detector iron (4 cm) + scintillators (1cm) beam 20 m B=1 T 40KT 50% wrongsignmuondetector not detected NC CC Hadron decay  Other Detectors: liquid argon TPC, water Cherenkov, emulsion can search for either e,  or  appearance

8. 8 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 1.3 Neutrino Factory physics reach  Can detect sign of  m 2 32 due to matter effects  Determine  13 and CP phase  simultaneously: need ~10 21 muons/year o Optimal CP phase sensitivity ~6000 km but can obtain >5  sensitivity for ~1000-8000 km

9. 9 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 2. Near detector aims o To achieve physics goals of neutrino factory, need to establish near detector for near/far ratio. o Long baseline neutrino oscillation systematics: –Flux control and measurement for the long baseline search. –Neutrino beam angle and divergence –Beam energy and spread –Control of muon polarization –Measurement of charm backgrounds o Near detector neutrino physics: –Cross-section measurements: DIS, QES, RES scattering –sin 2  W -  sin 2  W ~ 0.0001 –Parton Distribution Functions, nuclear shadowing –  S from xF 3 -  S ~0.003 _ –Charm production: |V cd | and |V cs |, D 0 / D 0 mixing –Polarised structure functions –  polarization –Beyond SM searches General Purpose Detector(s)!!

10. 10 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 2.1 Flux normalisation (cont.) o Neutrino beams from decay of muons: Spectra at Production (e.g. 50 GeV) Number CC interactions Polarisation dependence P  =+1: gone! Need to measure polarization!!

11. 11 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 2.1 Flux normalisation (cont.) o Rates: — E  = 50 GeV — L = 100 m, d = 30 m — Muon decays per year: 10 20 — Divergence = 0.1 m  /E  — Radius R=50 cm 100 m E.g. at 25 GeV, number neutrino interactions per year is: 20 x 10 6 in 100 g per cm 2 area. With 50 kg  10 9 interactions/yr Yearly event rates High granularity in inner region that subtends to far detector.

12. 12 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 2.1 Flux normalisation (cont.) o Neutrino flux normalisation by measuring: o Signal: low angle forward going muon with no recoil o Calculable with high precision in SM o Same type of measurement as for elastic scattering on electrons: E.g. CHARM II obtained value of sin 2  W from this

13. 13 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 2.2 Cross sections o Measure of cross sections in Deep Inelastic (DIS), Quasi- Elastic (QE) and Resonance Production (RES).  Coherent  background to many interactions) o Different nuclear targets: H 2, D 2 o Nuclear effects, nuclear shadowing, reinteractions With modest size targets can obtain very large statistics

14. 14 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 2.3 Parton Distribution Functions(s) o Unpolarised and Polarised Structure functions o  S from xF 3 -  S ~0.003 o Sum rules: e.g. Gross-Llewelyn Smith   polarization: spin transfer from quarks to  — NOMAD best data — Neutrino factory 100 times more data

15. 15 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 o mixing: doubly Cabbibo suppressed  SM very small, new physics o Babar: Rmix<4x10 -3 (90% CL) hep-ex/0408066 2.4 Charm Production o Charm production: o Measure of V cd and strange quark content nucleon o Measure charm vs p t (background to oscillations) o 6-7% of cross-section at 20 GeV  3% CC events: about 3x10 7 charm states per year McFarland Clean tagged sample

16. 16 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 2.5 sin 2  w o Elastic scattering off electrons: o Deep inelastic scattering: NC/CC Good statistical accuracy on sin 2  W (~0.5x10 -4 ) but hadron uncertainties dominate  sin 2  W ~ 0.0001

17. 17 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 o High granularity in inner region that subtends to far detector. o Very good spatial resolution: charm detection o Low Z, large X o o Electron ID o Does the detector have to be of same/similar technology as far detector? 3. Near detector requirements o Does not need to be very big (eg. R~50-100 cm) o Possibilities: — silicon or fibre tracker in a magnet with calorimetry, electron and muon ID (eg. NOMAD-STAR??) — Liquid argon calorimeter: problems with rate NOMAD-STAR (Silicon TARget)

18. 18 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 4. NOMAD-STAR  R&D in NOMAD for short baseline  detector based on silicon: NOMAD-STAR (NIMA 413 (1998), 17; NIMA 419 (1998), 1; NIMA 486 (2002), 639; NIMA 506 (2003), 217.) o Total mass: 45 kg of B 4 C target (largest density for lowest X 0 )

19. 19 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005  Aim of NOMAD-STAR: reconstruct short lived particles in a neutrino beam to determine capabilities  detection: use impact parameter signature of charm decays to mimic    impact parameter ~ 62  m, normal  charged current (CC) interactions ~30  m 4. NOMAD-STAR

20. 20 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 o Longest silicon microstrip detector ladders ever built: 72cm, 12 detectors, S/N=16:1  Detectors: Hamamatsu FOXFET p+ on n, 33.5x59.9 mm 2, 300  m thick, 25  m pitch, 50  m readout  VA1 readout: 3  s shaping 4. NOMAD-STAR

21. 21 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 4. NOMAD-STAR

22. 22 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005  CC event Primary vertex Secondary vertex 4. NOMAD-STAR

23. 23 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 o Most chips stable, but some chips showed varying level of noise o Maybe the same as charge build-up seen in Babar? 4. NOMAD-STAR

24. 24 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 o Increase noise in some ladders affected some efficiencies: compensated by clustering algorithm with cuts as function of ladder 4. NOMAD-STAR S/N 16 10

25. 25 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005  Vertex resolution:  y = 19  m  Impact parameter resolution: 33  m  Double vertex resolution: 18  m from K s reconstruction Pull:  ~1.02  x ~33  m 4. NOMAD-STAR  x ~18  m  z ~280  m

26. 26 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 o Charm event reconstruction: – Implementation of Kalman filter – Constrained fit method to extract charm signatures o Used NOMAD-STAR to search for charm events: marginal statistical accuracy, but was a good proof of principle 4. NOMAD-STAR

27. 27 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 o Efficiency very low: 3.5% for D 0, D + and 12.7% for D s + detection because fiducial volume very small (72cmx36cmx15cm), only 5 layers and only one projection. o From 10 9 CC events/yr, about 3.1x10 6 charm events, but efficiencies can be improved. 4. NOMAD-STAR

28. 28 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 o Passive target can provide target mass, but affects vertex and tracking reconstruction efficiency due to scatters o Improve efficiency by having fully active silicon target.  For example: 52 kg mass can be provided by 18 layers of Si 500  m thick, 50 x 50 cm 2 (ie. 4.5 m 2 Si) o Optimal design: fully pixelated detector (could benefit from Linear Collider developments in MAPS, DEPFET or Column Parallel CCD). Could also be with 3D detectors or silicon strips. o Other technologies: – Liquid argon TPC in a magnetic field: maybe rate is a problem – Scintillating fibre tracker – Standard gas TPC with target (likeT2K near detector), … o International Scoping Study (ISS) for a neutrino factory (July 2005 to August 2006): aim to define the scope of physics parameters, neutrino factory machine technology and detector technology needed to launch a full design study 2007-2010. Near detector will be considered within detector working group. 5. Near Detector Ideas

29. 29 Vertex 2005, Chuzenji Lake, Nikko, Japan. 10 November 2005 Vertex for CP. Conclusion o Haiku: unique form of very compact and succint Japanese poetry that captures the essence and beauties of nature. o Haiku poems consist of 3 verses of 5 syllables, 7 syllables and 5 syllables. Maximum exponent of Haiku poetry: Basho Matsuo (17 th century). o My own (humble) attempt at a Haiku poem: Leptogenesis, Oscillations to find,