Building a Tracking Detector for the P2 Experiment

Transcription

1 Building a Tracking Detector for the P Experiment DPG Frühjahrstagung, Hamburg 016 Marco Zimmermann Institute for Nuclear Physics March 3, 016

2 The P Experiment: Overview The Idea Precision measurement of the weak mixing angle at low Q Motivation Fundamental quantity of the Standard Model Sensitive for new Physics Method Measure parity-violating asymmetry in electron-proton scattering Mainz Energy-Recovery Superconducting Accelerator (MESA) M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

3 The P Experiment: Overview The Idea Precision measurement of the weak mixing angle at low Q Motivation Fundamental quantity of the Standard Model Sensitive for new Physics Method Measure parity-violating asymmetry in electron-proton scattering Mainz Energy-Recovery Superconducting Accelerator (MESA) M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

4 The P Experiment: Overview The Idea Precision measurement of the weak mixing angle at low Q Motivation Fundamental quantity of the Standard Model Sensitive for new Physics Method Measure parity-violating asymmetry in electron-proton scattering Mainz Energy-Recovery Superconducting Accelerator (MESA) M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

5 The Weak Mixing Angle θ W in the Standard Model (SM) Definition tan θ W = g g with SU() L U(1) Y gauge couplings g, g e e e e γ p p Proton electric charge +1 Z p p Proton weak charge 1 4 sin θ W M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, 016 / 11

6 Scale dependence of sin θ W e e e e e e e e γ p p +Z p p γ +γ p p Z +γ p p + On-shell definition sin θ W = 1 ( MW M Z ) induces large radiative corrections to weak neutral-current processes Absorb radiative corrections into effective, scale-dependent ( running ) sin θ W (Q ) M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

7 Scale dependence of sin θ W e e e e e e e e γ p p +Z p p γ +γ p p Z +γ p p + On-shell definition sin θ W = 1 ( MW M Z ) induces large radiative corrections to weak neutral-current processes Absorb radiative corrections into effective, scale-dependent ( running ) sin θ W (Q ) M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

8 Scale dependence of sin θ W e e e e e e e e γ p p +Z p p γ +γ p p Z +γ p p + On-shell definition sin θ W = 1 ( MW M Z ) induces large radiative corrections to weak neutral-current processes Absorb radiative corrections into effective, scale-dependent ( running ) sin θ W (Q ) M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

9 Running sin θ W Measurements Q W ( p ) Q W ( e ) Nu T ev Q W ( APV ) edis T e v atron LEP1 SLD A TLAS 0. 5 sin θ W ( Q ) CMS hs Q [ G e V ] M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

10 Running sin θ W Measurements 0.45 Q W ( p) Q W ( e) NuTeV 0.4 P@MESA Q weak Moller 0.35 SOLID 0.3 Q W ( APV ) edis Tevatron LEP1 SLD ATLAS 0.5 sin θ W ( Q ) CMS hs Q [GeV] M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

11 Measure sin θ W via Parity Violating ep-scattering Helicity + - Electron Beam Proton Target (lh ) Detector M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

12 Measure sin θ W via Parity Violating ep-scattering e e Helicity + - Electron Beam Proton Target (lh ) Parity violating asymmetry Photon exchange parity invariant Z-boson exchange violates parity! A PV N N + N +N + Flip helicity and count! Detector γ p e Z p p e p M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

13 Measure A PV in ep-scattering Helicity + - Electron Beam Proton Target (lh ) Detector A PV N N + N +N + = ( 1 4 sin θ W F(Q ) ) G F Q 4 πα Q = momentum transfer F(Q ) = proton form factor Need very high statistics and precise control of systematics 150 µa beam current, 000 h measuring time 60 cm liquid hydrogen target for high luminosity MESA beam Highly polarized ( 85 %), flip helicity at khz Low helicity-correlated uncertainties M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

14 Measure A PV in ep-scattering Helicity + - Electron Beam Proton Target (lh ) Detector A PV N N + N +N + = ( 1 4 sin θ W F(Q ) ) 30 ppb G F Q 4 πα Q = momentum transfer F(Q ) = proton form factor Need very high statistics and precise control of systematics 150 µa beam current, 000 h measuring time 60 cm liquid hydrogen target for high luminosity MESA beam Highly polarized ( 85 %), flip helicity at khz Low helicity-correlated uncertainties M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

15 Measure A PV in ep-scattering Helicity + - Electron Beam Proton Target (lh ) Detector A PV N N + N +N + = ( 1 4 sin θ W F(Q ) ) 30 ppb G F Q 4 πα Q = momentum transfer F(Q ) = proton form factor Need very high statistics and precise control of systematics 150 µa beam current, 000 h measuring time 60 cm liquid hydrogen target for high luminosity MESA beam sin θ W 0.13 % sin Highly polarized ( 85 %), flip helicity at khz θ W Low helicity-correlated uncertainties 0.1 ppb M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

16 P Detector Layout Solenoid Magnet Vacuum MESA Beamline Helium Liquid Hydrogen Target Photomultiplier Quartz Bars Tracking Layers Barrel Shield Support Frames M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

17 P Detector Layout Solenoid Magnet Vacuum MESA Beamline Helium Liquid Hydrogen Target Photomultiplier Quartz Bars Tracking Detector Two layer pairs 4 segments of 15 φ-coverage per layer Measure average Q Reconstruct individual electron tracks Tracking Layers Barrel Shield Support Frames M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

18 P Experiment Tracking Detector Conclusions Tracking Detector Layout 50 µm thin silicon High Voltage Monolithic Active Pixel Sensors (HV-MAPS) 50 µm thin Kapton layer Overlapping strips to maximize active area Less than 1 h of a radiation length per tracker layer 350 chips with size cm per segment M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

19 Challenges for the Tracking Detector Very high particle rates at full beam intensity O( 15 ) beam electrons per second Large amount of background, mostly bremsstrahlung photons Geometry Limited magnet length Inhomogeneous field Extended target ) Events/(s*mm MC Particle Rates on 1st Tracker Plane Secondary Electrons Scattered Electrons hitting Counting Detector Remaining Beam Electrons Photons R cyl /mm M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

20 Test the Detector Response to Photons Photon Background Continuous bremsstrahlung energy spectrum Photoelectric Effect Compton Scattering Pair Creation Events/s kinetic Energy / MeV Radioactive Sources X-ray Tube Upcoming photon beamtest at the existing Mainzer Miktroton (MAMI) beam facility M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, 016 / 11

21 Summary and Conclusions P Experiment Measure sin θ W at low Q in parity violating ep-scattering Start data taking around 00 A PV measurement with integrating Cherenkov detectors Tracking Detector Q Measurement and systematic studies Low material budget Very high (background) particle rates Detailed track finding and reconstruction studies ongoing Development of mechanical layout started M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

22 Thank you for your attention. M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

23 Backup M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

24 Sensitivity to New Physics Hooman Davoudiasl, Hye-Sung Lee, and William J. Marciano Phys. Rev. D 89, E158 Qweak first Ν DIS m dark Z 0 MeV m dark Z 00 MeV sin ΘW Q APV Cs PVDIS 0.3 APV Ra Moller MESAQweak SOLID LEP 0.30 ''Anticipated sensitivities'' SLAC Log Q GeV M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

25 Beam Stability Requirements Achieved at MAMI A PV uncertainty requirement Energy fluctuation 0.04 ev < 0.1 ppb ok! Position fluctuation 3 nm 5 ppb 0.13 nm Angle fluctuation 0.5 nrad 3 ppb 0.06 nrad Intensity fluctuation 14 ppb 4 ppb 0.36 ppb M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

26 Systematic Uncertainties M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

27 y/z-box processes uncertainty contribution Re z - Avg. (Model I,II) Re z ± ( z) e e Re z(e, t=0) P QWEAK (E = GeV) E (GeV) γ Z p p M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

28 Projection of Expected Electron Trajectories 1500 Projection of electron trajectories r/mm FOPI_real Solenoid, B = 0.60 T max B = 0.96*B max Target z = -700 mm E beam = MeV el. e-p-scattering: θ [5.00 deg, deg] el. e-p-scattering: θ [0.00 deg, deg] el. e-e-scattering: θ [5.00 deg, deg] z/mm M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

29 Expected Particle Rates on First Plane Hit Distribution in Tracking plane 0, z = 81 ) Events/(s*mm Signal Electrons hitting ICD Other hard scattered electrons Secondary electrons Beam electrons (no hard scattering) Photons Positrons Protons 3 4 Events/(pixel*50ns) R cyl /mm 9 M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

30 Expected Particle Rates on Second Plane Hit Distribution in Tracking plane 1, z = 11 ) Events/(s*mm Signal Electrons hitting ICD Other hard scattered electrons Secondary electrons Beam electrons (no hard scattering) Photons Positrons Protons 3 4 Events/(pixel*50ns) R cyl /mm 9 M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

31 Expected Particle Rates on Third Plane Hit Distribution in Tracking plane, z = 1640 ) Events/(s*mm Signal Electrons hitting ICD Other hard scattered electrons Secondary electrons Beam electrons (no hard scattering) Photons Positrons Protons 3 4 Events/(pixel*50ns) R cyl /mm 9 M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

32 Expected Particle Rates on Fourth Plane Hit Distribution in Tracking plane 3, z = 1660 ) Events/(s*mm Signal Electrons hitting ICD Other hard scattered electrons Secondary electrons Beam electrons (no hard scattering) Photons Positrons Protons 3 4 Events/(pixel*50ns) R cyl /mm 9 M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, 016 / 11

33 Photon Background First Tracker Plane Hit Distribution in Tracking plane 0, z = 81 Continuous bremsstrahlung energy distribution Secondary electrons mainly produced by photo-effect Low detection rate of higher energetic photons Reduced rate of secondary electrons on covered plane Detailed investigation of detector response to low energy photons needed ) Events/(s*mm Events/s Signal Electrons hitting ICD Other hard scattered electrons Secondary electrons Beam electrons (no hard scattering) Photons Positrons Protons R cyl /mm Kinetic Photon energy in Plane z=81 9 kinetic energy of photons without sec. el. kinetic energy of photons with sec. el Events/(pixel*50ns) kinetic Energy / MeV M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

34 Photon Background Second Tracker Plane Hit Distribution in Tracking plane 1, z = 11 Continuous bremsstrahlung energy distribution Secondary electrons mainly produced by photo-effect Low detection rate of higher energetic photons Reduced rate of secondary electrons on covered plane Detailed investigation of detector response to low energy photons needed ) Events/(s*mm Events/s Signal Electrons hitting ICD Other hard scattered electrons Secondary electrons Beam electrons (no hard scattering) Photons Positrons Protons R cyl /mm Kinetic Photon energy in Plane z=11 9 kinetic energy of photons without sec. el. kinetic energy of photons with sec. el Events/(pixel*50ns) kinetic Energy / MeV M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

35 Photon Production Processes Hit Dist. of Photons in Tracking plane 0, z = 81 Hit Dist. of Photons in Tracking plane, z = 1640 ) Events/(s*mm ProductionType 0 ProductionType 3 ProductionType Events/(pixel*50ns) ) Events/(s*mm 7 ProductionType ProductionType 3 ProductionType Events/(pixel*50ns) R /mm 1 cyl Hit Dist. of Photons in Tracking plane 1, z = R /mm 3 cyl Hit Dist. of Photons in Tracking plane 3, z = 1660 ) Events/(s*mm ProductionType 0 ProductionType 3 ProductionType Events/(pixel*50ns) ) Events/(s*mm 7 ProductionType ProductionType 3 ProductionType Events/(pixel*50ns) cyl /mm R cyl /mm R process encoding: 0 = bremsstrahlung in the target, 3 = bremsstrahlung in other detector parts, 5 = pair annihilation M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

36 Photon Vertices Truth vertex of photons hitting Tracking plane 0, z = 81 r/mm z/mm M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

37 MC Detector Response to Photons Detector Response to Photons 3 Detector Response to Photons det η 1 Detector Response to Photons Detector Response to Photons by Photoelectric Effect det η 0.7 Detector Response to Photons Detector Response to Photons by Photoelectric Effect Detector Response to Photons by Compton Scattering Detector Response to Photons by Pair Creation 0.6 Detector Response to Photons by Compton Scattering Detector Response to Photons by Pair Creation Photon Energy/MeV Photon Energy/MeV Detector Response to Photons 3 Detector Response to Photons det η Detector Response to Photons Detector Response to Photons by Photoelectric Effect det η Detector Response to Photons by Compton Scattering Detector Response to Photons by Pair Creation Detector Response to Photons Detector Response to Photons by Photoelectric Effect Detector Response to Photons by Compton Scattering Detector Response to Photons by Pair Creation Photon Energy/MeV Photon Energy/MeV M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

38 Secondary Electrons Production Processes ) Events/(s * mm Hit Dist. of sec. electrons in Tracking plane 0, z = 81 ProductionType ProductionType 1 ProductionType 13 ProductionType 14 R /mm cyl Hit Dist. of sec. electrons in Tracking plane 1, z = 11 ) Events/(s * mm ProductionType ProductionType 1 ProductionType 13 ProductionType Events/(pixel*50ns) Events/(pixel*50ns) ) Events/(s * mm 6 ProductionType ProductionType 1 5 ProductionType 13 ProductionType Hit Dist. of sec. electrons in Tracking plane, z = 1640 R /mm cyl Hit Dist. of sec. electrons in Tracking plane 3, z = 1660 ) Events/(s * mm ProductionType ProductionType 1 ProductionType 13 ProductionType Events/(pixel*50ns) Events/(pixel*50ns) cyl /mm R cyl /mm R Process encoding: = ionisation, 1 = Photoeffect, 13 = Compton Scattering, 14 = Pair creation M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

39 Background Electrons Hitting Integrating Cherenkov Detector Production Vertices Truth vertex of backgr. electr. hitting Integrating Detector r/mm z/mm M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11

40 Additional Electron Loss due to Segmented Tracker Layers Particle rates at subsequent tracking planes normalized to the first one relative particle rate h_nd_plane h_3rd_plane h_4th_plane φ Coverage/deg M.Zimmermann (Institute for Nuclear Physics) Tracking Detector for P March 3, / 11