Review of future short baseline accelerator experiments M. Shaevitz - PowerPoint PPT Presentation

1 Review of future short baseline accelerator experiments M. Shaevitz - Columbia University

2 Hints for High Δ m 2 ~1 eV 2 Oscillation ⇒ Sterile Neutrinos? or Something Else? • Positive indications: ν µ → ν →ν e ν µ → ν e New MiniBooNE ν µ → ν →ν e Combined ν + ν ν e → ν e Now 3.8 σ ν ν e → →ν e • Negative indications: – CDHS and MiniBooNE restrictions on ν µ disappearance – MiniBooNE restrictions on ν µ disappearance – MINOS restrictions on ν µ → ν s New MiniBooNE/SciBooNE – Karmen restrictions on ν µ →ν e Limits on ν µ / ν µ Disappearance – Other negative results

3 Phenomenology of Oscillations with Sterile Neutrinos (3+1) Models • In sterile neutrino (3+1) models, appearance comes from oscillation through ν s – ν µ → ν e = ( ν µ → ν s ) + ( ν s → ν e ) • (3+1) models require ν µ and ν e disappearance oscillations – ν µ → ν s and ν e → ν s – Constraints from disappearance restrict application of (3+1) fits • Current measurements of appearance and (3+2) Models disappearance are not very compatible with (3+1) models ⇒ (3+2) models – If ν µ → ν e and ν µ →ν e are different then CP violation allowed in 3+2 (3+2) models can have CP violation – Still tension between appearance and disappearance

Reactor Antineutrino Anomaly 4 § New Reactor antineutrino Spectra § Net 3% upward shift in energy-averaged fluxes § Phys. Rev. C83, 054615, 2011 § Recent re-analysis of 19 reactor neutrino results § Neutron life time correction & Off- equilibrium effects § Phys. Rev. D83, 073006, 2011 § Obs/Pred = 0.927±0.023 (3 σ ) § At least three alternatives: § Wrong prediction of ν -spectra ? § Bias in all experiments ? § New physics at short baselines: Mixing with 4 th ν -state

5 Reactor Antineutrino Anomaly

6 Combined Gallium and Reactor Allowed Region (3+1)

7 Global Fits to Appearance and Disappearance Results • In 3+1 models, hard to reconcile ν e / ν e appearance/disappearance with ν µ / ν µ disappearance – Compatibility among data sets for 3+1 fits less than 1% Giunti, Laveder arXiv:1111.1069 • 3+2 models better since there can be CP violating interference

8 New MiniBooNE ν ν µ →ν ν e • ν µ → ν e and ν µ →ν e becoming more compatible with a common oscillation hypothesis and with the LSND result

Preliminary (3+2) Fits to New MiniBooNE ν e / ν ν e Appearance 9 Global 3+2 Fits Preliminary ν µ → ν e including new MiniBooNE ν µ →ν e Data - C. Ignarra (MIT) Preliminary • Two high mass scales plus CP violation effects can possibly explain ν e vs ν e appearance • Still some tension ν µ →ν e with disappearance results. Preliminary Preliminary

10 Many Ideas for Future Experiments • Establishing the existence of sterile neutrinos would be a major result for particle physics • Need definitive experiments – Significance at the > 5 σ level – Observation of oscillatory behavior (L and/or E dependence) within a detector or between multiple detectors – Oscillation signal clearly separated from backgrounds • Need to make both appearance and disappearance oscillation searches for neutrinos and for antineutrinos – Needed to prove the consistency with sterile neutrino (3+1) and (3+2) models • Very active area for the field with many proposals and ideas – “Light Sterile Neutrinos: A White Paper” (arXiv:1204.5379) put together by a group of over 170 experimentalists and theorists. – Many workshops investigating opportunities and possibilities

11 Future Experimental Oscillation Proposals Type of Exp App/Disapp Osc Channel Experiments Nucifer, Stereo, ν e →ν e Reactor Source Disapp SCRAMM, NIST, Neutrino4, DANSS Baksan, LENS, Borexino, ν e →ν e Radioactive Sources Disapp SNO+, Richochet, ( ν e → ν e ) CeLAND, Daya-Bay ν e →ν e Isotope Source Disapp IsoDAR ν µ →ν e Pion / Kaon Decay- Appearance OscSNS, CLEAR, DAE δ ALUS, KDAR at-Rest Source & Disapp ν e → ν e ( − ) MINOS+, MicroBooNE, ν µ → ν e , ν µ →ν e Accelerator ν using Appearance LAr1kton+MicroBooNE, Pion Decay-in-Flight & Disapp ν µ → ν µ , ν e → ν e CERN SPS ν e → ν µ , ν e →ν µ ν STORM at Fermilab Low-Energy Appearance ν -Factory ν µ → ν µ , ν e → ν e & Disapp

12 Very-short Baseline Oscillation Experiments ν - Source ν - Detector Radioactive Source or Reactor Source or Proton into Dump Source ( ) 1/ L 2 flux rate modulated by Prob osc = sin 2 2 ! " sin 2 # m 2 L / E • 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/L 2 ) to search for oscillations • Backgrounds produce fake events that do not show the oscillation L/E behavior and are easily separated from signal

13 Very-Short Baseline Reactor Experiments ( ν ν e Disappearance )

14 Very-Short Baseline Reactor Experiments Experiment Reactor Baseline Status Nucifer Osiris 7 Taking Data (Saclay) 70MW Stereo ILL 10 Proposal (Genoble) 50 MW SCRAMM San-Onofre 24 Proposal (CA) 3 GW NIST NCNR 4-11 Proposal (US) 20 MW NEUTRINO4 SM3 6-12 Proposal 100 MW SCRAMM ATR 12 Proposal (Idaho) 150 MW DANSS KNPP 14 Fabrication (Russia) 3 GW

15 NUCIFER Reactor Experiment Osiris Research Reactor: Core Size : 57x57x60 cm 1.2m x 0.7m detector , 7m distance from core 5 σ

16 Radioactive β -Decay Source Experiments ( ν e or ν ν e Disappearance )

17 Radioactive β -Decay Source Experiments Species Source Experiment Status ν e 51 Cr Baksan Proposal ν e 51 Cr LENS Proposal ν e 51 Cr Borexino Proposal ν e 51 Cr SNO+ Proposal ν e 37 Ar Richochet Proposal  ν e 144 Ce Ce-LAND Proposal  ν e 144 Ce Daya-Bay Proposal

18 Ce-LAND Exp: Using 144 Ce kCi Anti-neutrino Source § A 50 kCi anti- ν source (10 g of 144 Ce) in the middle of a large LS detector § Inside a thick 35 cm W-Cu shielding à background free § Energy-dependent oscillating pattern in event spatial distribution M. Cribier, et al. PRL 107, 201801(2011) 1 yr 95%CL 5 σ Detectors which could be used for this idea include Kamland, SNO+, or Borexino …

19 Isotope Decay-at-Rest Neutrino Source ( ν ν e Disappearance )

20 IsoDAR ν ν e Disappearance Exp (arXiv:1205.4419) • High intensity ν e source using β -decay at rest of 8 Li isotope ⇒ IsoDAR • 8 Li produced by high intensity (10ma) proton beam from 60 MeV cyclotron ⇒ being developed as prototype injector for DAE δ 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 … . cyclotron protons Blanket/ Detector Target Shield • Physics measurements: – ν e disappearance measurement in the region of the LSND and reactor- neutrino anomalies. – Measure oscillatory behavior within the detector.

21 IsoDAR 60 MeV Proton Cyclotron (Under Development)

DAE δ DALUS 800 MeV Cyclotron System 22 (Under Development) DAR Target-Dump + Ion H 2 (about 6x6x9 m 3 ) Source IsoDAR Cyclotron Injector Cyclotron (Resistive Isochronous) Ring Cyclotron (Superconducting) “Isochronous cyclotron” where mag. field changes with radius, but RF does not change with time. This can accelerate many bunches at once.

IsoDAR at Kamland 23

24 IsoDAR Neutrino Source and Events • p (60 MeV) + 9 Be → 8 Li + 2p – plus many neutrons since low binding energy • n + 7 Li (shielding) → 8 Li 8 Li → 8 Be + e − + ν e • – Mean ν e energy = 6.5 MeV – 2.6 × 10 22 ν e / yr arXiv:1205.4419 • Example detector: Kamland (900 t) – Use IBD ν 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

25 IsoDAR ν ν e Disappearance Oscillation Sensitivity (3+1) ν e →ν e 5 σ 5 yrs

26 Oscillation L/E Waves in IsoDAR Observed/Predicted event ratio vs L/E including energy and position smearing ν e →ν e ν e →ν e 5 yrs 5 yrs IsoDAR’s high statistics and good L/E resolution gives good sensitivity to distinguish (3+1) and (3+2) oscillation models

27 Pion or Kaon Decay-at-Rest Neutrino Sources

28 Decay-at-Rest (or Beam Dump) Neutrino Sources Cyclotron or Other Proton Source Decay-at-Rest gives ν µ ( >800 MeV proton for π production) isotropic neutrino source Dump e + µ + ν e proton π + ? e c n a r a ν µ e p π − p a s i D Captures ν e before decay Appearance? ν e Each π + decay gives one ν µ , one ν e , and one ν µ with known energy spectrum ~1 ma of 800 MeV protons (like LSND) ⇒ 0.17 π + /proton ⇒ 2.3 × 10 24 ν / yr