Searching for Sterile Neutrinos with an Isotope β-decay Source: The IsoDAR Experiment

1. Searching for Sterile Neutrinos with an Isotope β-decay Source: The IsoDAR Experiment Mike Shaevitz - Columbia University Aspen Winter Workshop--New Directions in Neutrino Physics February 8, 2013

2. Where Are We With Sterile Neutrinos? • Several hints of oscillations through sterile neutrino state with m2  1 eV2 • LSND / MiniBooNE e /e appearance • Reactore disappearance (“Reactor Anomaly”) • Radioactive source e disappearance • But still no indication of  disappearance • Establishing the existence of sterile neutrinos would be a major result for particle physics but ….. • Need definitive experiments • Significance at the > 5 level • Observation of oscillatory behavior within detector • Several directions for next generation experiments • Multi-detector accelerator neutrino beam experiments • Very short baseline (VSBL) experiments with compact neutrino sources Some difficulty for fitswith one or twosterile neutrino models - App vs Disapp-  vs

3. e s ? Daya Bay RENO 3  4  Region to Explorefor Sterile Neutrinos Current ReactorExperiments Older ReactorExps at Close DistancesR = 0.927  0.023 (3.0  ) Hase Disappearance Been Observed?  Reactor Antineutrino Anomaly near detectors Red: 3 sin2(2θ13) = 0.15 Blue: 4 ∆m2new = 2 eV2 and sin2(2θnew)=0.12, with sin2(2θ13) = 0.085 arXiv: 1204.5379

4. Very-short Baseline Oscillation Experiments  - Source  - Detector Radioactive SourceorIsotope SourceorReactor SourceorProton into Dump Source • Can observe oscillatory behavior within the detector if neutrino source has small extent . • Look for a change in event rate as a function of position and energy within the detector • Bin observed events in L/E (corrected for the 1/L2) to search for oscillations • Backgrounds produce fake events that do not show the oscillation L/E behavior and can be separated from signal

5. Possible Sources for VSBL Experiments Need experiments with L/E ~ 1 m/MeV • Reactor sources • E ~ 3 MeV  optimum distance around 3 to 20 m • Reactor core size can also be an issue • Radioactive sources • E ~ few MeV  see oscillations with wavelengths ~ 1m • Compact source can be placed directly into detector or just outside • Isotope neutrino source • E ~ 8 MeV (typical of short lived isotopes, i.e. 8Li) • Distance to source can be longer 10m to 20m • Compact source that can be set up near an existing large detector • Beam can be turned off periodically to measure background • Higher energy neutrinos with less background

6. IsoDAR ExperimentIsotope Decay-at-Rest Neutrino Source (e Disappearance )

7. DAR Target-Dump (about 6x6x9 m3) H2+ IonSource InjectorCyclotron(ResistiveIsochronous) Ring Cyclotron(Superconducting) “Isochronous cyclotron” wheremag. field changes with radius, but RF does not change with time. This can accelerate many bunches at once. DAEDALUS 800 MeV Cyclotron System (Under Development) IsoDARCyclotron

8. Columbia, Huddersfield, IBA, Maryland, MIT, PSI, INFN-Catania, INFN –Legnaro, RIKEN, Wisconsin Academics: Neutrino Physicists, Accelerator Physicists And also Scientists at a Corporation Submitted to NIM

9. Phase I: The Ion Source Injector Target/ Dump Ion source Superconducting Ring Cyclotron

10. Ion Source: By our collaborators at INFN Catania. Produces sufficient H2+! (>30 mA required in order to accelerate 5 mA. Most beam is lost in the first turns.) solenoid lens source slits & diagnostics

11. Beam to be characterized at Best Cyclotrons, Inc, Vancouver This spring (NSF funded) Results to be available by Cyclotrons’13 Conference, Sept 2013, Vancouver

12. We have a workable ion source for a Phase II Injector Target/ Dump Ion source Superconducting Ring Cyclotron IsoDAR: A sterile neutrino experiment On its own!

13. protons Blanket/Shield Detector cyclotron Target Overview IsoDARe Disappearance Exp • High intensitye source using -decay at rest of 8Li isotope  IsoDAR • 8Li produced by high intensity (10ma) proton beam from 60 MeV cyclotron being developed as prototype injector for DAEALUS cyclotron system • Put a cyclotron-isotope source near one of the large (kton size) liquid scintillator/water detectors such as KAMLAND, SNO+, Borexino, Super-K…. • Physics measurements: • e disappearance measurement in the region of the LSND and reactor-neutrino anomalies. • Measure oscillatory behavior within the detector as a function of L and E. Phys Rev Lett 109 141802 (2012) arXiv:1205.4419

14. p (60 MeV)  +  9Be  8Li  +  2p plus many neutrons since low binding energy n + 7Li (shielding)  8Li 8Li  8Be + e +e Meane energy = 6.5 MeV 2.61022e / yr Example detector: Kamland (900 t) Use IBDe + p  e+ + n process Detector center 16m from source ~160,000 IBD events / yr 60 MeV protons @ 10ma rate Observe changes in the IBD rate as a function of L/E 5 yrs IsoDAR Neutrino Source and Events arXiv:1205.4419

15. Potential Location of  Source Currently working with the Kamland collaboration on the details of siting and installation of the cyclotron, beamline, and neutrino source. IsoDAR at Kamland

16. Detecte Events using Inverse Beta Decay (IBD)

17. e e 5 5 yrs IsoDAR e Disappearance Oscillation Sensitivity (3+1)

18. IsoDAR Measurement Sensitivity

19. 5 yrs 5 yrs Oscillation L/E Waves in IsoDAR Observed/Predicted event ratio vs L/E including energy and position smearing e e e e IsoDAR’s high statistics and good L/E resolution has potential to distinguish (3+1) and (3+2) oscillation models

20. Possibility to Probe Lower m2 using Super-K

21. Beyond Oscillations:IsoDAR sin2W Measurement

22. ee Elastic Scattering  Measure sin2W • NuTeV weak mixing angle measurement using neutrino neutral current scattering differs from expectation by 3 • Is there something special with neutrinos or difficulty in NuTeV analysis?  Use IsoDAR/Kamland to measure sin2W with pure lepton process antineutrino-electron elastic scattering:e + e  e + e

23. Backgrounds are large since signal is single outgoing electron Visible energy is low since outgoinge takes away energy Kamland Backgrounds toee Signal • Cuts: • Evis > 3 MeV-  (to source) < 250 •  Reduce isotropic bkgnd by x2 electron kinematics From L. Winslow Use large sample of IBD eventsto constrain normalization to 0.2%

24. IsoDAR sin2W Measurement Sensivity • 5yr data (7200 evts with Evis>3MeV)  IsoDAR/Kamland: sin2W = 0.0075 (~3%) • Not as good as NuTeV: sin2W = 0.2277  0.0016 (0.7%) • But would be bestee elastic scattering measurement(See 3% band below)

25. Final Comments • Establishing the existence of sterile neutrinos would be a major result for particle physics • Several hints in the m2 ~1 eV2 region • Some tension with lack of  disappearance signals • Many proposals and ideas for sterile neutrino searches • New experiments to have better sensitivity (~5 level) with capabilities to see oscillatory behavior. • IsoDAR could make a definitive search for sterile neutrinos • Advantage over reactor and radioactive sources in having neutrinos with x3 higher energy • Source is compact with a very well understood energy spectrumand can be setup near an existing large detector • Combined L and E analysis can isolate the oscillatory behavior and reduce backgrounds • Can turn beam off to measure background • R&D is well underway to produce a high-intensity compact 60 MeV cyclotron to drive the neutrino source (See talk by Matt Toups)

26. Backup

27. e LSND and MiniBooNE Indications ofe Appearance MiniBooNEAllowed Regions

28. Future Experimental Oscillation Proposals/Ideas ()

29. Use IsoDARe Source for Coherent NC Measurement • High intensity isotropic neutrino beam with well known spectrum • Advantages: • About x2 higher energy than reactor neutrinos (but lower flux) • IsoDAR experimental site should offer a close, low-background location to put a ~ton scale coherent scattering detector • Can turn off cyclotron to give measurement of non-beam backgrounds • Source size ~0.5m so might explore doing an oscillation search with coherent scattering events. • Can vary distance with cyclotron beam to multiple  sources • Can go deep to reduce cosmic backgrounds • Do dark matter searches during cyclotron-off periods • Disadvantage: • To get needed rates, one needs to push the detection thresholds down to the few keV range • High-intensity cyclotron needs to be developed

30. Visible Energy Spectrum for LAr and LNe Integral = 690 events Ethresh > 1keV Ethresh > 1keV LNe @ 10m1ton for 1 yr LAr @ 10m1ton for 1 yr

31. Example Coherent Rates with 1ton LArgon with IsoDAR

32. Visible Energy Spectrum for Ge Detectors 475 events/yr EThresh > 20 eV Ge @ 10m100kg for 1 yr

33. Overview • High-power cyclotrons can be used to make an intense, compact neutrino source. • Daedalus CP violation program using 800 MeV proton cyclotrons • High intensity DAR source of to complement long-baseline neutrino oscillation program • Use NC coherent scattering to search for  STERILE with DAR beam • IsoDAR sterile neutrino experiment using a 60 MeV proton cyclotron • Cost effective, intense , compacte source from 8Li isotope decay. • Synergy with industrial interest in medical isotope production • High intensity IsoDAR typee source could also be used for a neutral current coherent neutrino scattering experiment • Need to couple the IsoDAR source with a low threshold (~few keV) 10 to 1000 kg detector

34. Engineering Study of Sector Magnet for the Daedalus Experiment, http://arxiv.org/abs/1209.4886 Engineering design, Assembly Plan, Structural analysis, Cryo system design