1. An Improved Limit on the Muon Neutrino Mass from Pion Decay in Flight Carmen-Miruna Anăstăsoaie Alex Eduardo de Bernardini Sven Lafèbre Martin Vlček NuMass Experiment International Summer School on Particle and Nuclear Astrophysics in Nijmegen 2003

2. What is the aim of the project? NuMass will improve the value of the upper limit of the mass of the muon neutrino. Current limits: m( e )  4.35 - 15 eV Tritium  - decay endpoint  23 eV TOF spread from SN1987A  0.5 - 9 eV Double  - decay for Majorana ’ s m(   170 keV  ( stopping  ’ s ) m(   18.2 MeV Inv. Mass of  hadrons (e + e - Colliders) Nijmegen’03 improvement by NuMass by order of 20 to m(  ) < 8 keV

3. History of the Muon Neutrino Mass Limit Nijmegen’03

4. Why is this measurement so important? verification of theoretical backgrounds - neutrino mass generation mechanism - complementary information to neutrino oscillation results - neutrino decays understanding - chiral left-right symmetry improvement of the theoretical description of the Fermi constant understand some loopholes in cosmology - lack of dark matter - limits to the density of Universe minimal left-right model verification some propagation phenomena related to supernova pulses it is, after all, a fundamental constant ! Nijmegen’03

5. Highlights of the experimental technique “ origin ” In a perfectly uniform magnetic field any charged particle returns to origin independent of B or p or angle Uniformity is more important value of B Nijmegen’03

6. Highlights of the experimental technique  Injection decay   orbit 24 g-2 calorimeters restrict late decays identify electron bkg initial beam tuning C-veto: restrict incoming  ’s J-veto: restrict early  ‘s at large angles J-cal: 2nd turn electron id Beam counter S1S2 Trigger Hodoscope Nijmegen’03  observed event by event we will need SEB

7. Highlights of the experimental technique NuMass will use the existing G-2 Storage Ring in the BNL facility at Brookhaven with only minor modifications Nijmegen’03

8. Highlights of the experimental technique Embedded Scintillator: 2 mm Prescale Strips Trigger pads Beryllium Degrader S2 S1 Silicon μ-strip Detectors Nijmegen’03

9. Endpoint structure Expected distance between first pass pion and second pass muon (in mm) Nijmegen’03

10. Highlights of the experimental technique Electronics and trigger: - simple triple coincidence - cheap - comercially available Nijmegen’03

11. Sources of background Beam-gas scatters => vacuum is 10 -6 torr Injected p (27 %) => rejected in embedded scintilatorsΔT = 7 ns / turn slower Injected e (12 %) => rejected in J-veto, calorimeter or position, lose 1 MeV / turn μ → e => rejected by g-2 calorimeter < 10 -4 of good π-μ events π → e  => rejected by calorimeter in inner J-veto Nijmegen’03 J-Veto S1S2 g-2 Cal’s C-Veto

12. Advantages of NuMass run in dedicated mode or in conjuction with K-decay (E949) or MECO experiment another project may run nearly immediately after our beamtime, there are only minor changes on beam pure 2 body decay  no model dependent nuclear/atomic environment Nijmegen’03

13. Responsibilities Beamline and RingBNL SSD and readout electronicsCERN, Minnesota Active Vetoes and Scint TriggerBU, Illinois, Tokyo IT Feedthrus and positionersTokyo IT, Heidelberg, BNL DAQ and g-2 electronicsMinnesota, BU Field MeasurementsYale, Heidelberg, BNL Orbital dynamics, Monte CarloCornell, BNL, Yale, NYU, Minnesota, BU AnalysisThe team! Nijmegen’03

14. Budget $ 770kBNL - modifications on G-2 and SEB - improved sensitivity for the V1 beamline instrumentation - beam time $ 330kCERN, Universities - silicon detectors, degrader, active vetoes - feedthrus, positioners - electronics, DAQ $ 1.1 MTOTAL COST Nijmegen’03

15. Scheduling Year 2000 build 2-SSD detectors plus removable degrader unit build active vetos or simple prototype write software for new electronics readout and integrate with g-2 Year 2001 install and test prototype detectors by running parasitically understand the π-μ orbital parameters test AGS/beamline modifications for slow extraction to g-2 build and test final silicon detector + degrader Year 2002 commission slow extraction to g-2 run the experiment parasitically with E 949 Year 2003 dedicated experiment or further parasitic running to completion Nijmegen’03

16. Thank you for your attention...

18. Neutrino oscillation Neutrino oscillation experimental results are theoretically dependent. Some effects surrounding the standard formulation of neutrino oscillation phenomena: (flavor) quantum number oscillation existence of sterile neutrino understanding of the mixing angles chiral oscillation Dirac formulation of neutrino oscillation matter effect wave packet description Nijmegen’03

19. Neutrino oscillation Neutrino oscillation experimental results are theoretically dependent. Some effects surrounding the standard formulation of neutrino oscillation phenomena: Neutrino oscillation  Δm2Δm2 DIRECT !!! (flavor) quantum number oscillation existence of sterile neutrino understanding of the mixing angles chiral oscillation Dirac formulation of neutrino oscillation matter effect wave packet description I’m 

20. If you believe atmospheric neutrino result:   =>    with only  m 2 ~.002 Then this experiment reduces the  neutrino mass limit by 3 orders of magnitude! Nijmegen’03 Neutrino oscillation

21. Inflector Degrader T0J-Veto collimator Pion on orbit pion => pion residual profile Muon hits J-Veto on 1st turn Flash Counter pion 2nd time around Nijmegen’03

22. Some background configurations 5 mm endpt (q=70 MeV/c) SR shrinks it 2 mm  e   e g-2 Calorimeters J-Calorimeter Nijmegen’03

23. Cross section of g-2 superconducting magnet Nijmegen’03

24. Cross section of the field Contours every 1 ppm of field gradient represents lines every 1.5 μTesla Magnetic field is 1.45 Tesla Nijmegen’03

25. Proposed Parasitic Running with AGS Crystal Extraction E949 Running Conditions 25 Gev protons 70 TP in a 4.1 s spill / 6.4 s cycle E952 Parameters 2.8 x 10 6    into g-2 ring/TP 5.4 x 10 12    for an 8 keV result Triggers Offline Entering Ring Detector   +vetoes 8 x 10 6 part/s 1 x 10 6 part/s 1.8 x 10 5 s -1 910 s -1 42 s -1 400 Hz/strip 55  s/SSD 11 ms/SSD 100 MB/s 0.5 MB/s Prescale in trigger Instantaneous rates (100% extr. eff.) Running Time 5% of SEB beam => 492 hrs (crystal extr. eff.) Nijmegen’03