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MOLLER Spectrometer Update

MOLLER Spectrometer Update. Juliette M. Mammei. Future Priorities (from last meeting). Lower priority. Physicist input to engineering (highest priority) Magnetic force studies Sensitivity studies Design of the water-cooling and electrical services

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MOLLER Spectrometer Update

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  1. MOLLER Spectrometer Update Juliette M. Mammei

  2. Future Priorities (from last meeting) Lower priority • Physicist input to engineering (highest priority) • Magnetic force studies • Sensitivity studies • Design of the water-cooling and electrical services • Radiation doses (brought up by companies) • Optimization of the optics • He bag/central beam pipe • Multiple magnets • No negative bend • Iron in coils • Engineering work (MIT/Bates) • Design of support structure • Vacuum vessel design MOLLER Collaboration Meeting May 8,9 2014

  3. Bids MOLLER Collaboration Meeting May 8,9 2014 • Forces with asymmetric coils • http://ace.phys.virginia.edu/MollerSpectrometer/297 (Jason) • http://ace.phys.virginia.edu/MollerSpectrometer/298 (Juliette) • http://ace.phys.virginia.edu/MollerSpectrometer/299 (Juliette) • http://ace.phys.virginia.edu/MollerSpectrometer/300 (Juliette) • Radiation dose on coils • http://ace.phys.virginia.edu/MollerSpectrometer/305 (Tyler) • http://ace.phys.virginia.edu/MollerSpectrometer/306(Seamus) • Coil sensitivities • http://ace.phys.virginia.edu/MollerSpectrometer/287 (Sakib, Juliette preliminary) • http://ace.phys.virginia.edu/MollerSpectrometer/308 (Tyler) • See slides • Support Structure • See slides • Vacuum vessel • See slides

  4. Forces New Old Coil off Forces on coil to beam left with adjacent coil off MOLLER Collaboration Meeting May 8,9 2014

  5. Forces Old New Coil off MOLLER Collaboration Meeting May 8,9 2014

  6. Sensitivity Studies • Need to consider the effects of asymmetric coils, misalignments etc. on acceptance • This could affect our manufacturing tolerances and support structure • Have created field maps for a single coil misplaced by five steps in: • -1° < pitch < 1° • -4° < roll < 4° • -1° < yaw < 1° • -2 < r < 2 cm • -10 < z < 10cm • -5° < φ < 5° Axes in frame of single coil MOLLER Collaboration Meeting May 8,9 2014

  7. Sensitivity Studies What are the relevant ,, , We’ll measure a certain rate R and asymmetry A in each septant. We assume the allowable uncertainty on A to be 0.1 ppb Slopes give, for example, Then , the uncertainty in z allowed Our ability to determine in that septant may also be important. MOLLER Collaboration Meeting May 8,9 2014

  8. MOLLER Collaboration Meeting May 8,9 2014

  9. Asymmetry vs. position offset

  10. Asymmetry vs. rotation offset

  11. Preliminary Results Fit to plots is given by in range where approximately linear Then, for example, (>10 cm over magnet length) where What about physical constraints? MOLLER Collaboration Meeting May 8,9 2014

  12. MOLLER Collaboration Meeting May 8,9 2014

  13. Closest approach MOLLER Collaboration Meeting May 8,9 2014

  14. Summary • These results have some simulations with same random seed (statistical uncertainty is not as good as it seems) • Need to re-run those simulations and redo the results • All plots vs. offset treated as linear, though some clearly are not • Very preliminary results show order ~3 mm sensitivities (not sub-mm) • Need to look at the effect of tracking algorithm with incorrect maps • What is the most important parameter – what is it that will determine the sensitivity • A background correction done incorrectly? • The mean asymmetry, as I’ve assumed here? • The mean θlab, which will go into the extraction of sin2θW? MOLLER Collaboration Meeting May 8,9 2014

  15. Neutron shielding MOLLER Collaboration Meeting May 8,9 2014

  16. Radiation dose MOLLER Collaboration Meeting May 8,9 2014

  17. Support Structure MOLLER Collaboration Meeting May 8,9 2014

  18. Frame Design MOLLER Collaboration Meeting May 8,9 2014

  19. Vacuum Chamber design MOLLER Collaboration Meeting May 8,9 2014

  20. Cut away views MOLLER Collaboration Meeting May 8,9 2014

  21. Stress and deformation analysis MOLLER Collaboration Meeting May 8,9 2014

  22. Bids? MOLLER Collaboration Meeting May 8,9 2014

  23. Extra Slides MOLLER Collaboration Meeting May 8,9 2014

  24. Tracks in GEANT4 for nominal field Mollers eps MOLLER Collaboration Meeting May 8,9 2014 (Rate weighted 1x1cm2 bins)

  25. MOLLER Collaboration Meeting May 8,9 2014

  26. Slopes give, for example, Then , the uncertainty in z allowed What are the relevant ,, , We’ll measure a certain R and A in each septant. What matters is our ability to determine in that septant. MOLLER Collaboration Meeting May 8,9 2014

  27. Assuming The uncertainty on is: ~ 0.001 GeV ~ 0.001 GeV ~ 1.33 GeV2/rad MOLLER Collaboration Meeting May 8,9 2014

  28. θlow,down θhigh,down Finite Target Effects θhigh,up Router θlow,up Assume 5.5 mrads at upstream end of target, instead of center Rinner ztarg,up ztarg,center ztarg,down

  29. Looking downstream φ=-360°/14 φ=+360°/14 ͢ B Bx By By Bx x r In this septant: By ~ Bφ Bx ~ Br φ y MOLLER Collaboration Meeting May 8,9 2014

  30. GEANT4 • Moved to GDML geometry description • Defined hybrid and upstream toroids • Parameterized in same way as the TOSCA models MOLLER Collaboration Meeting May 8,9 2014

  31. GEANT4 - Collimators MOLLER Collaboration Meeting May 8,9 2014

  32. GEANT4 – Acceptance definition MOLLER Collaboration Meeting May 8,9 2014

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