Neutrinos from Stored Muons STORM physics with a μ storage ring

Outline  Historical context  Physics motivation  The facility  Physics potential  Project considerations  Moving forward and Conclusions 2 Alan Bross CERN January 24th, 2013

Historical Context

Introduction  For over 30 years physicists have been talking about doing experiments with s from  decay  Flavor content fully known  “Near Absolute” Flux Determination is possible in a storage ring  Beam current, polarization, beam divergence monitor,  p spectrometer  Overall, there is tremendous control of systematic uncertainties with a well designed system  Initially the motivation was high-energy interaction physics.  BUT, so far no experiment has ever been done! 4 Alan Bross CERN January 24th, 2013

30 Years in the Making  First proposed in detail by David Neuffer in 1980 at the Telemark Wisconsin workshop on neutrino mass 5 Alan Bross CERN January 24th, 2013 The technology existed then & It certainly exists now Note: First Reference: 50 GeV beam – Koshkarev Here in 1974

P-860 (1990)  A Search for Neutrino Oscillations Using the Fermilab Debuncher Slide from 1991 PAC Presentation Alan Bross CERN January 24th,

Muons in the Debuncher? Alan Bross CERN January 24th,

The Birth of the Neutrino Factory TopCite 500+ “Renowned Paper” Alan Bross CERN January 24th,

physics with a μ storage ring 9 12 channels accessible if E  is above the  threshold Alan Bross CERN January 24th, 2013 For the past decade+, the focus has been on oscillation physics

Neutrino Factory Studies  Study 1 (US-Fermilab) [2000]  Study 2 (US-BNL) [2001]  NuFact-J study [2001]  CERN NF study [2002]  Study 2a (APS Multidivisional Neutrino Study) [2004]  ISS (first international study; ISS group) [2006]  One finishing up  International Design Study for a NF  RDR ready by September 2013  But will supply input to Snowmass ‘13 10 Alan Bross CERN January 24th, 2013

International Design Study for a Neutrino Factory (IDS-NF)  The baseline NF in the 2011 IDS-NF Interim Design Report (IDR) is the high-energy (E  =25 GeV) machine, two-baseline facility:  Proton Driver  4 MW, 2 ns bunch  Target, Capture, Drift (π → μ) & Phase Rotation  Hg Jet  200 MHz train  Cooling  30  mm (  )  150  mm ( L )  Acceleration  103 MeV  25 GeV  Decay rings  7500 km L  4000 km L  Focused on reaching the highest possible sensitivity for very small  Alan Bross CERN January 24th, 2013 Figure of Merit:  0.15  end of cooling channel

The NF Goal was To Know what we “Don’t” Know 12 Alan Bross CERN January 24th, 2013 We do Now Is the NF Concept Still Relevant?

NF in context of  13  9 o Current status of IDS-NF design  Simpler Facility – New IDS-NF baseline  Single baseline ( km)  Lower E  = 10 GeV (eliminate final acceleration stage)  Still gives best  cp coverage & precision  But is still quite expensive 13 Alan Bross CERN January 24th, 2013

YES  nuSTORM  It is a NEAR-TERM FACILITY  Because, technically, we can do it now  Addresses the large  m 2 oscillation regime  Provides beam for precision  interaction physics  Provides a  decay ring R&D (instrumentation) & technology demonstration platform  Accelerator technology test bed  potential for intense low E muon beam  Provides a Detector Test Facility Is there an affordable  -based beam “First Step”? 14 Alan Bross CERN January 24th, 2013

15 Alan Bross CERN January 24th, kW So, here is where we are with the NF This is the simplest implementation of the NF And DOES NOT Require the Development of ANY New Technology This is what we want to do near-term: Neutrinos from STORed Muons, STORM 3.8 GeV/c stored 

Physics motivation & Theoretical Considerations Beyond the SM

Short-baseline oscillation studies  Sterile neutrinos arise naturally in many extensions of the Standard Model.  GUT models  Seesaw mechanism for mass  “Dark” sector  Usually heavy, but light not ruled out.  Experimental hints  LSND  MiniBooNE  GA  Reactor “anomaly” 17 Alan Bross CERN January 24th, 2013 Kopp, Machado, Maltoni & Schwetz (work in progress) & arXiv: ". 3+1

3 + 2 Models 18 Alan Bross CERN January 24th, 2013  Models with 2 sterile neutrinos provide better fits to the data arXiv: v arXiv: Kopp, Maltoni & Schwetz

3 + 3 Model  A 3+3 model has recently been shown to better fit all available data 19 Alan Bross CERN January 24th, 2013 J.M. Conrad, C.M. Ignarra, G. Karagiorgi, M.H. Shaevitz, J. Spitz (arXiv: v1)

From Kopp, Maltoni & Schwetz In conclusion, we have shown that a global fit to short baseline oscillation searches assuming two sterile neutrinos improves significantly when new predictions for the reactor neutrino flux are taken into account, although some tension remains in the fit. We are thus facing an intriguing accumulation of hints for the existence of sterile neutrinos at the eV scale, and a confirmation of these hints in the future would certainly be considered a major discovery. 20 Alan Bross CERN January 24th, 2013

Interaction Physics

Cross-section measurements  The next generation of LB experiments face some significant challenges  CP asymmetry decreases with increasing sin 2 2  13  Well…. I should say that the CP asymmetry IS small  Flux and cross-sections must be known to much better than 5%  Gaining a better understanding of x-sections may be crucial to these future experiments  The energy range of interest is roughly 1-3 GeV   storage rings provide the only way to get large sample of e and  interactions (both neutrino and anti-neutrino) in a single experiment and:  With  decay ring instrumentation we anticipate getting the flux uncertainty below 1% and  With a well designed suite of near detectors, x-sections can be measured to the few % level or less.  Great deal of ND work for LBNE, LBNO & IDS-NF  Reach an overall systematic uncertainly that is very difficult (impossible?) in conventional beams 22 Alan Bross CERN January 24th, 2013

Cross-section measurements  Cross-section measurements   storage ring presents only way to measure   &  e & ( ) x-sections in same experiment  Supports future long-baseline experiments 23 Alan Bross CERN January 24th, 2013 Important to note that with θ 13 large, the asymmetry you’re trying to measure is small, so: – Need to know underlying ν/νbar flux & σ more precisely – Bkg content & uncertainties start to become more important

A detector for interaction physics One Example 24 Alan Bross CERN January 24th, 2013  HiResM  Evolution of the NOMAD experiment  One of the concepts considered for ND for LBNE  Studied as ND for NF  Capabilities  High resolution spectrometer  Low density  PID & tracking  Nuclear targets Sanjib Mishra

Interaction Physics A partial sampling  e and e -bar x-section measurements   0 production in interactions  Coherent and quasi-exclusive single  0 production  Charged  & K production  Coherent and quasi-exclusive single  + production  Multi-nucleon final states  -e scattering  -Nucleon neutral current scattering  Measurement of NC to CC ratio  Charged and neutral current processes  Measurement of e induced resonance production  Nuclear effects  Semi-exclusive & exclusive processes  Measurement of K s 0,  -bar production  New physics & exotic processes  Test of   - e  universality  Heavy  eV-scale pseudo-scalar penetrating particles 25 Alan Bross CERN January 24th, 2013 Over 60 topics (thesis) accessible at nuSTORM

The Facility

Baseline(s)  100 kW Target Station  Assume 60 GeV proton  Fermilab PIP era  Au target  Optimization on-going  Horn collection after target  Li lens has also been explored  Collection/transport channel  Two options  Stochastic injection of   Kicker with   decay channel  At present NOT considering simultaneous collection of both signs  Decay ring  Large aperture FODO  Racetrack FFAG  Instrumentation  BCTs, mag-Spec in arc, polarimeter 27 Alan Bross CERN January 24th, GeV/c stored 

 -base beam: Oscillation channels 28 8 out of 12 channels potentially accessible Alan Bross CERN January 24th, 2013

 Production, Capture & Transport 29 Alan Bross CERN January 24th, 2013 In momentum range 4.5 < 5.0 < 5.5 Obtain  0.11  ± /pot with 60 GeV p & NuMI-style horn Heavy metal target Target/capture optimization ongoing Sergei Striganov Ao Liu Fermilab 80% Collection + Transport Efficiency L » 20m

 Transport & p beam absorber 30 Alan Bross CERN January 24th, 2013

Injection Concept  π’s are on an injection orbit  separated by chicane  μ’s are in ring circulating orbit  lower p ~3.8 GeV/c  ~30cm separation between 31 Alan Bross CERN January 24th, 2013  Concept works for FODO lattice  Now detailed by Ao Liu  Work in progress for RFFAG David Neuffer’s original concept from 1980

 s at end of first straight 32 Alan Bross CERN January 24th, 2013 Ao Liu Fermilab

FFAG Racetrack 33 Alan Bross CERN January 24th, 2013 Low dispersion in straight Y. Mori & JB Lagrange Kyoto A. Sato Osaka

RFFAG Dynamic Aperture 34 Alan Bross CERN January 24th, 2013

FODO vs. RFFAG 35 Alan Bross CERN January 24th, 2013

E  spectra (  + stored) 36 Alan Bross CERN January 24th, 2013 Integrated over the 150 m straight at a position 50m from the end of the straight with 3m diameter detector NOTE: The transport line and ring could be re-tuned for 2 GeV/c  and move these spectra lower by » a factor of two with some drop in  production efficiency

The Physics Reach Appearance (Golden) Channel for sterile(s) search

Assumptions  N  = (POT) X (  /POT) X  collection X  inj X (  ) X A dynamic X   POT in 5 years of 60 GeV in Fermilab PIP era  0.1  /POT (FODO)   collection = 0.8 (collection off horn + decay in transfer line)   inj = 0.8   = 0.08 (  ct X  capture in  decay) [  decay in straight]  Might do better with a  decay channel  A dynamic = 0.75 (FODO)   = Straight/circumference ratio (0.43) (FODO)  This yields  1.7 X useful  decays 38 Alan Bross CERN January 24th, 2013

E  spectra (  + stored) 39 Alan Bross CERN January 24th, 2013 e  -bar Event rates/100T at ND hall 50m from straight with  + stored

Experimental Layout 40 Alan Bross CERN January 24th, 2013 Must reject the “wrong” sign  with great efficiency Appearance Channel: e   Golden Channel Why   e Appearance Ch. not possible 150 ~ 1500 m

Baseline Detector Super B Iron Neutrino Detector: SuperBIND  Magnetized Iron  1.3 kT  Following MINOS ND ME design  1-2 cm Fe plate  5-6 m diameter  Utilize superconducting transmission line for excitation  Developed 10 years ago for VLHC  Extruded scintillator +SiPM 41 Alan Bross CERN January 24th, cm hole For 3 turns of STL

Simulation –  appearance  Full GEANT4 Simulation  Extrapolation from ISS and IDS-NF studies for the MIND detector  Uses GENIE to generate the neutrino interactions.  Involves a flexible geometry that allows the dimensions of the detector to be altered easily (for optimization purposes, for example).  Does not yet have the detailed B field, but parameterized fit is very good  Event selection/cuts  Cuts-based analysis  Multivariate in development 42 Alan Bross CERN January 24th, 2013 Ryan Bayes Glasgow

Event reconstruction efficiency 43 Alan Bross CERN January 24th, 2013 Left: 1 cm plates, Right: 2 cm plates

Backgrounds 44 Alan Bross CERN January 24th, 2013 Left: 1 cm plates Right: 2 cm plates

Raw Event Rates & Sensitivities 45 Alan Bross CERN January 24th, Assumption Appearance channels Chris Tunnell Oxford

e    appearance CPT invariant channel to MiniBooNE 46 Alan Bross CERN January 24th, cm plate

ExperimentS:B LSND2:1 MiniBooNE1:1  1:2 LAr-LAr1:4 K + DAR  4:1 LSND Reloaded5:1 oscSNS3:1 S:B for Appearance Channel Past and Future(?) 47 Alan Bross CERN January 24th, 2013  Note: There are a number of experiments with megaCi to petaCi sources next to large detectors that have an exquisite signature of steriles (# evts/unit length displays oscillatory behavior in large detector) and have large effective S:B  SNO+Cr, Ce-Land, LENS, Borexino, Daya Bay  IsoDAR  A number of very-short baseline reactor experiments

Systematics for Golden Channel in nuSTORM  Magnetic field uncertainties  If we do as well as MINOS (3%), no impact  Need high field, however. STL must work  Cross sections  Needs some more work  ND for disappearance ch (100T of SuperBIND) should minimize contribution to the uncertainties  Cosmic rays  Not issue  Detector modeling (EM & Hadronic showering)  Experience from MINOS indicates we are OK, but this needs more work for SuperBIND  Atmospheric neutrinos  Negligible  Beam and rock muons  Active veto – no problem 48 Alan Bross CERN January 24th, 2013

e    appearance CPT invariant channel to LSND/MiniBooNE 49 Alan Bross CERN January 24th, Assumption Chris Tunnell Oxford Uncertainties: 2% systematic 40% background

Required  charge mis-ID rate needed for given sensitivity 50 Alan Bross CERN January 24th, 2013 Chris Tunnell Oxford

Multivariate Analysis CC-NC discrimination 51 Alan Bross CERN January 24th, 2013 Ryan Bayes Steve Bramsiepe Glasgow  2 cm plates  Updated reconstruction  Tested 3 multi- variate methods  KNN  BDT  MLP  Goal to reduce threshold & increase eff.

Background rates 52 Alan Bross CERN January 24th, 2013

MVA vs Cuts-based analysis 53 Alan Bross CERN January 24th, 2013

Disappearance Experiments

Raw Event Rates 55 Alan Bross CERN January 24th, Assumption Appearance channels Tremendous Statistical Significance

Disappearance channels But:  Need self-consistent two-detector simulation including (bin-to-bin) uncorrelated shape error ~ 10%  A challenge: there may be oscillations already in near detectors  Geometry important for  m 2 ~ 10 1 – 10 3 eV 2  Suitability (& optimization) of SuperBIND for e channels still needs to be studied 56 Alan Bross CERN January 24th, 2013 Walter Winter Würzburg

Project Considerations

Siting Concept 58 Alan Bross CERN January 24th, 2013

Site Detail 59 Alan Bross CERN January 24th, 2013

MI-40 Beam Absorber 60 Alan Bross CERN January 24th, 2013

Far Detector Hall and Detector(s) 61 Alan Bross CERN January 24th, 2013

Looking to the Energy Frontier 62 Alan Bross CERN January 24th, 2013 Only 40% of  s decay in straight Need  absorber

Low Energy  beam 63 Alan Bross CERN January 24th, 2013 After 3.27m Fe, we have   /pulse in 200 < P(MeV/c) < 500 At end of straight we have a lot of  s, but also a lot of  s with 4.5 < P(GeV/c) < 5.5

Input beam for some future 6D  cooling experiment(s) 64 Alan Bross CERN January 24th, 2013

Siting at CERN  The facility could be implemented in the SPS North Area following in the steps of ICARUS/NESSiE  100 GeV fast extracted protons from SPS is assumed  Roughly 100 kW on target  For the same integrated power on target, the same sensitivities can be reached  Target station, transport line and decay ring designs could be the same, or very similar.  Biggest difference would be in civil construction due to the differences in the site constraints at the two labs 65 Alan Bross CERN January 24th, 2013

Protons from the SPS 66 Alan Bross CERN January 24th, 2013

North Area 67 Alan Bross CERN January 24th, 2013

International Collaboration 68 Alan Bross CERN January 24th, 2013  Although it is obvious that the Host Laboratory has to carry the burden of the civil construction, most of the effort on the project could be shared between collaborating institutions  Target  Horn  Magnets and magnet systems (ps, controls, etc)  Capture-Transport Channel  Decay ring  Detectors

Moving Forward

The “Collaboration” P. Kyberd, 1 D.R. Smith, 1 L. Coney, 2 S. Pascoli, 3 C. Ankenbrandt, 4 D. Adey 4, S.J. Brice, 4 A.D. Bross, 4 H. Cease, 4 J. Kopp, 4 N. Mokhov, 4 J. Morfin, 4 D. Neufer, 4 M. Popovic, 4 P. Rubinov, 4 S. Striganov, 4 A. Blondel, 5 A. Bravar, 5 F. Dufour 5, Y. Karadhzov 5, A. Korzenev 5,E. Noah, 5 M. Ravonel 5, M. Rayner 5, R. Asfandiyarov 5, A. Haesler 5, C. Martin 5, E. Scantamburlo 5, F. Cadoux 5, R. Bayes, 6 F.J.P. Soler, 6 D. Colling 7, A. Dobbs, 7 J. Dobson 7, P. Dornan 7, K. Long, 7 J. Pasternak, 7 E. Santos, 7 J.K. Sedgbeer 7, M.O. Wascko, 7 Y. Uchida 7, S.K. Agarwalla, 8 S.A. Bogacz, 9 Y. Mori, 10 J.B. Lagrange, 10 A. de Gouvêa, 11 Y. Kuno, 12 A. Sato, 12 V. Blackmore, 13 J. Cobb, 13 C. D. Tunnell, 13 A. Webber 13, J.M. Link, 14 P. Huber, 14 and W. Winter 15, K.T. McDonald 16, R. Edgecock 17, W. Murray 17, S. Ricciardi 17, C. Rogers 17, C. Booth 18, M. Dracos 19, N. Vassilopoulos 19, J.J. Back 20, S.B. Boyd 20, P.F. Harrison 20 1 Brunel University, 2 University of California, Riverside, 3 Institute for Particle Physics Phenomenology, Durham University 4 Fermi National Accelerator Laboratory, 5 University of Geneva 6 University of Glasgow, 7 Imperial College London, 8 Instituto de Fisica Corpuscular, CSIC and Universidad de Valencia, 9 Thomas Jefferson National Accelerator Facility, 10 Kyoto University, 11 Northwestern University, 12 Osaka University, 13 Oxford University, Subdepartment of Particle Physics, 14 Center for Neutrino Physics, Virginia Polytechnic Institute and State University 15 Institut für theoretische Physik und Astrophysik, Universität Würzburg 16 Princeton University, 17 STFC Rutherford Appleton Laboratory, 18 University of Sheffield, 19 IPHC, Universit´e de Strasbourg, 20 University of Warwick 70 Alan Bross CERN January 24th, 2013 LOI submitted to Fermilab PAC, June 2012 (P=1028) nuSTORM: input to the update of the European Strategy for Particle Physics, July 2012

Ongoing & future work  Facility  Targeting, capture/transport & Injection  Need to complete detailed design and simulation  Decay Ring optimization  Continued study of both RFFAG & FODO decay rings  Decay Ring Instrumentation  Define and simulate performance of BCT, polarimeter, Magnetic-spectrometer, etc.  Produce full G4Beamline simulation of all of the above to define flux (Fermilab PhD student - thesis)  And verify the precision to which it can be determined. 71 Alan Bross CERN January 24th, 2013

Ongoing & future work II  Detector simulation  For oscillation studies, continue MC study of backgrounds & systematics  Start study of disappearance channels  Look in detail at all sources of backgrounds: CR, atmospheric, etc.  Will lead to detector (FAR) optimization  In particular the event classification in the reconstruction needs optimization.  Move to Multivariate techniques. [Begun]  For cross-section (& general interaction physics) measurements need detector baseline design  Learn much from work for LBNE & IDS-NF (both detector & physics)  Increased emphasis on e interactions, however 72 Alan Bross CERN January 24th, 2013

Important steps to move forward  Two workshops are planned  CERN: March (contact: Elena Wildner)  Virginia Tech: April (contact: Jon Link  Aim:  Consolidate technical options  Define work-packages  Identify possible collaborative topics  Discussion on the collaborative EOI to CERN SPC (to be ready by April ‘13)  Ken Long, Elena Wildner  Production of Full Proposal to Fermilab ( June 2013 PAC & Snowmass)  2 Years out – TDR in EU, CD process in US 73 Alan Bross CERN January 24th, 2013

nuSTORM: Conclusions The Physics case:  Initial simulation work indicates we can confirm/exclude at 10  (CPT invariant channel) the LSND/MiniBooNE result   and ( e ) disappearance experiments delivering at the <1% level look to be doable  Systematics need careful analysis  Detailed simulation work on these channels has not yet started  interaction physics studies with near detector(s) offer a unique opportunity & can be extended to cover 0.2<GeV< E < 4 GeV  Could be “transformational” w/r to interaction physics  For this physics, nuSTORM should really be thought of as a facility: A “light-source” is a good analogy  nuSTORM provides the beam & users will bring their detector to the near hall 74 Alan Bross CERN January 24th, 2013

Conclusions II The Facility:  Presents very manageable extrapolations from existing technology  But can explore new ideas regarding beam optics and instrumentation  Offers opportunities for extensions  Add RF for bunching/acceleration/phase space manipulation  Provide  source for 6D cooling experiment with intense pulsed beam 75 Alan Bross CERN January 24th, 2013

So… nuSTORM :  Delivers on the physics for the study of sterile  Offering a new approach to the production of beams setting a 10  benchmark to confirm/exclude LSND/MiniBooNE  Can add significantly to our knowledge of interactions, particularly for e  Provides an accelerator technology test bed  Provides a powerful detector test facility 76 Alan Bross CERN January 24th, 2013

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