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Window of Opportunity

Window of Opportunity. … Physics . There are mysteries in the neutrino mass spectrum which a complementary, direct measurement can help unravel. Oscillation Exp. only sensitive to D m 2 n disappearance => oscillation => mass 2-flavor mixing is much easier to write down

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Window of Opportunity

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  1. Window of Opportunity … Physics ... There are mysteries in the neutrino mass spectrum which a complementary, direct measurement can help unravel. Oscillation Exp. only sensitive to Dm2n disappearance => oscillation => mass 2-flavor mixing is much easier to write down Astrophysics/Cosmologyno sterile n, standard model interactions, stable n Supernovaeonly applies to Dirac neutrinos model-dependent at supernuclear densities … Experiment … G-2 storage ring: state-of-the-art spectrometer at bargain prices Beamlinecan be parasitic with SEB, easily switched to RHIC, FEB An order of magnitude improvement in a fundamental constant

  2. A stricter limit is part of this decade’s focus on neutrino physics PRESENT Atmospheric: nm=> nXand Dm2 ~.0012 - .008 eV2 (SuperK: nm=> nt slightly favored) Solar Neutrino: ne => nX and Dm2 ~ 10-6eV2 or is it 10-11 eV2 ? (SNO may help) LSND nm => ne and Dm2 ~ .03-1.0 eV2 FUTURE MINOS - Beams early 2004 CERN - Beams early 2005 K2K - 220 evts by 2005 (if Dm2 large) MiniBoone in 2003, Boone in ?? The next Supernova - Tools to interpret and limit

  3. Closing Loopholes Neutrino decay nm -> ne ne ne via DLo (minimal LR symmetric model) consistent with Mass Density of UniversePrimordial nucleosynthesis Microwave Bkgd Diffuse g-ray Bkgd SN1987a as long as m(nm) > 35 keV (from Z-width) Supernovae For m(nX)> 10 keV, Dt ~ day => pulse is below background if SNO sees no delayed pulse, then take your pick:No nX produced? Oscillated to n(sterile)? They decayed? nm is massive? Check out all those 17 keV papers for more exotic loopholes

  4. dGF dtm 5dmm 4m2 GF 2tm 2mmm2m nm 0.5 ppmMuLan 10 ppm 0.38 ppm It is, after all, a Fundamental Constant ! Its uncertainty affects our knowledge of other fundamental constants For example: * Mass of the pion as measured by decay of stopped p’s * Gfermi theoretical precision negligible compared to experimental variables other electroweak variables, such as MZ, continue to improve

  5. Direct Measurements are …more direct! Current Limits m(ne)< 4.35 - 15 eV Tritium b-decay endpoint < 23 eV TOF spread from SN1987A< 0.5 - 9 eV Double b-decay for Majorana n’s m(nm) < 170 keV p -> mn (stopping p’s) m(nt) < 18.2 MeV Inv. Mass of t -> n + hadrons (e+e- Colliders)

  6. DIRECT MEASUREMENTS OF M(nm) Pure 2-body decay p -> m n No model-dependent nuclear/atomic environment Pions live a reasonably long time Pion Decay at RestParent pmomentum is well-known Limited by the uncertainty in the pion mass Pion Decay in Flight Need to measure pp-pm Momentum Resolution limited by mult.scattering in detectors

  7. Pion Decay at Rest Series of experiments at PSI 1979:Daum et al. (Phys Rev D20 p.2692) Solution A Solution B 1984:Abela et al (Phys Lett B146 p.431) Solution A Solution B 1996:Assamagan et al. (Phys RevD53 p.6065) Solution A Solution B m2(nm) = + 0.13 +- 0.14 - (MeV/c2)2 m(nm) < 570 keV/c2 m2(nm) = - 0.163 +- 0.080 - (MeV/c2)2 m(nm) < 250 keV/c2 m2(nm) = - 0.143 +- 0.024 -0.016 +- 0.023 (MeV/c2)2 m(nm) < 170 keV/c2

  8. Pion Decay in Flight 1982:Anderhub et al. Phys Lett B114 p.76 m2(nm) = - 0.14 +- 0.20 (MeV/c2)2 m(nm) < 500 keV/c2 2002:BNL g-2 Neutrino Mass Experiment? m(nm) < 8 keV/c2 If SuperK definitively proves nm=> nt (Dm2~.007) Then this experiment reduces the t neutrino mass limit by 3 orders of magnitude!

  9. Highlights of the Experimental Technique • Translate Dp to Dr in 0.1 ppm uniform B-Fieldno multiple scattering no need to measure decay angle or location • Reference each m to parent pslow extraction • In situ alignmentprotons (7 ns/turn late) prescaled undecayed pions remote positioning of active vetoes remote angular adjustment of detector • Position resolution from silicon1.4 mm SSD • Time resolution from scintillators and PMT’stight triple coincidence trigger TDC’s on all vetoes and embedded hodoscope

  10. In a perfectly uniform B-fieldAny charged particle returns to origin independent of B, p, q * Origin can produce a range of angles and momenta * Uniformity is more important than value of B* 1st harmonic (and other nonuniformities) are always monitored using residuals of prescaled pions and undecayed protons “origin”

  11. G-2 Storage Ring G-2 Experiment Weak-focussing Storage Ring: Muons stored for 800 ms Quadrupoles Muon Kicker NuMass Experiment Spectrometer: p -> mn observed evt-by-evt No Quads Pion kicker Same Momentum - 3 GeV retain excellent shimming and B-field uniformity 0.1 ppm over 4.5 cm Trolley runs in vacuum to map field Fixed probes to track changes Active shimming and thermal insulation to minimize change

  12. Put pions on orbit using dE/dx Injection 5.2 cm Beryllium p orbit withoutdegrader p orbit with degrader “Pion Kicker” D p = -16.2 MeV/c X/Xo = 14.7 %q (rms) = 1.56 mr

  13. Conceptual Design Forward-going decay muons orbit a larger diameter byDD CM nm p m q = 29.7 MeV/c undecayed pions D DD pm - pp 0.7 MeV/c 3.26 mmD pp3 GeV/c 14 m DD decay m’s dD depends on m(n) non-zero mn shrinks DD dD -mn2 D 2 q mp 0.04 mm for current limit

  14. DD pm - pp 0.7 MeV/c 3.26 mmD pp3 GeV/c 14 m Conceptual Design Forward-going decay muons orbit a larger diameter byDD CM nm p m q = 29.7 MeV/c undecayed pions D DD decay m’s

  15. dD depends on m(n) non-zero mn shrinks DD dD -mn2 D 2 q mp 0.04 mm for current limit

  16. J-Veto Non-forward going muons are lower momentum They move to the inside of S2 Also vetoed offline by the g-2 calorimeters and J veto g-2 Cal’s S1 S2

  17. Experimental Method Beam counter p Injection J-veto: restrict early m‘s at large anglesJ-cal: 2nd turn electron id 24 g-2 calorimetersrestrict late decays identify electron bkginitial beam tuning C-veto: restrict incoming p’s decay m p orbit S1 S2 Trigger Hodoscope

  18. Silicon mstrip Detectors (S1, S2)(1.28 cm long vertical strips at 50 mm pitch) S2 Embedded Scintillator:2 mm Prescale Strips Trigger pads S1 6.4 cm BerylliumDegrader 2.56 cm

  19. 32 strips per Viking chipserial readout into 1 ADC @40MHz = 0.8 ms

  20. Sample & Hold Readout System Simple Standard Cheap 225 ns Beam Counter 150 ns Hodoscope Trigger:latch data p 1st turn: S1 (ch 6) O m 2nd turn: S1 (ch 71) O 1st turn: S2 (ch 6) p O m S2 (ch 71) 2nd turn: O

  21. Running Time 5% of SEB beam => 492 hrs (crystal extr. eff.) Parasitic Running E952 Parameters2.8 x 106p+into g-2 ring/TP5.4 x 1012p+for an 8 keV result E949 Running Conditions 25 Gev protons70 TP in a 4.1 s spill / 6.4 s cycle Triggers Offline Entering Ring Detector p-pp-m (p-m)+vetoes 8 x 106 part/s 1 x 106 part/s 1.8 x 105 s-1 910 s-1 42 s-1 400 Hz/strip 55 ms/SSD 11 ms/SSD 100 MB/s 0.5 MB/s Instantaneous rates (100% extr. eff.) Prescale in trigger

  22. Scintillator Hodoscope Radial segmentation = 2 mm Vertical segmentation = 12.8 mm • 4 ns gate for 3-fold coincidence triggerAccidentals at 0.004, flagged by beam counter • Veto events Dr < 2mm to enrich p-m eventsx 50 prescale => 0.5 MB/s or 37 DLT tapes • Select readout SSD0.7% dead time 1/10 data volume • 1 ns timing resolution (TDC) + 2mm segmentationreject accidentals offline (another factor of .002)

  23. Sources of Background • Beam-gas scattersvacuum is 10-6 torr • Injected p (27%)7 ns/turn slower • Injected e (12%)lose 1 MeV/turn from SR (4.7 mm inward) identify in J-Veto calorimeter (or position) • m => enn(gt = 64 ms)injected m (1%) and p =>mn < 10 -4 of good p -m events rejected by g-2 calorimeters • p => en (BR=1.2 x 10-4)low tail out to ~ 5 mm calorimeter at inner J-Veto

  24. Some Background Configurations p -> e n p -> mn J-Calorimeter g-2 Calorimeters m -> enn 5 mm endpt (q=70 MeV/c) SR shrinks it 2 mm

  25. Schedule Summer 2000 Test individual SSD’s at CERN Spring 2001 Do tests at end of g-2 run (fast extraction) Insert 2 SSD’s in rigid frame with removable “degrader” p-inj, low intensity, no quads, no kicker No degrader: m-m, p-J-veto Degrader: m- J-veto, p-p Summer 2001Test of crystal extraction for Slow Beam 2001 Build mosaic of SSD Customize VA readout (chip run) Tests of detector at CERN test beam 2002 Engineering run - parasitic with E949 Crystal extraction: slow beam down V-line Final 5x5 SSD configuration with degrader in ring 2002 Physics run - parasitic or dedicated

  26. Responsibilities Beamline and Ring BNL SSD and readout electronics CERN, Minnesota Active Vetoes and Scint Trigger BU, Illinois, Tokyo IT ?? Feedthrus and positioners Tokyo IT, Heidelberg ??, BNL DAQ and g-2 electronics Existing (Minnesota, BU) Field Measurements Yale, Heidelberg, BNL Orbital dynamics, Monte Carlo Cornell, BNL, Yale, NYU, Minn, BU Analysis The team!

  27. Goals of the 2001 Test Run • Check out trigger and DAQ modifications • Read out silicon microstrip prototype detector in g-2 conditions • Beamline settings for pion injection link to position of pion and muon at detector and J-veto most efficient angle thru inflector • Map scattering background in g-2 Cal, FSD, J-Veto • Practice tightening profile using beamline • Practice tightening profile using current shims

  28. Problems: Fast extraction, high intensity, msec shaping timeConditions: No vacuum, no kicker, no quads, reverse B-field • Inject positive pions at 0.5% above magic momentum • Observe trigger hodoscope(TDC and ADC gives 2 rough profiles 150 ns apart) • No degraderFind 1st pass pion distribution and 2nd pass muon distribution Some storage: tune on fast rotation in detectors Check lifetimes of lost muons vs positrons in FSD’s See pions at Flash Counter on 1st turn • DegraderFind 1st pass pion and 2nd pass pion distribution No storage: Check lifetime of lost muon distribution No pions on Flash Counter Muons scraped off inner J-Veto after 1st pass and pions after 2nd • Read out microstrip detector as well, but unable to do residuals..yet • Gradually reduce emittance and then reduce intensity How low a rate can we get? Can we find the on-orbit protons 7 ns later? • Watch FSD, PSD and CAL detectors, collect information on the scattered background - electrons? muons? • Delay S2 microstrip trigger to remove 1st pass in S2

  29. S1 12.8 mm 12.8 mm Prototype SSD’s from CERN g-2 Test setup S2 PSD tiles Trigger tiles Removable Copper sheets

  30. Using VA-2 chip: 800 ns shaping time 225 ns Beam Counter 150 ns Hodoscope Trigger S2 Trigger S1 p 1st turn: S1 (ch 6) O m 2nd turn: S1 (ch 71) O 1st turn: S2 (ch 6) p O m S2 (ch 71) 2nd turn: O More Accidentals and More Deadtime

  31. T0 J-Veto Inflector Flash Counter Pion hits inflector Muon on orbit collimator No Degrader pion => muon residual profile

  32. T0 J-Veto Inflector Flash Counter Pion on orbit Muon hits J-Vetoon 1st turn pion 2nd time around collimator Degrader pion => pion residual profile

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