A Letter of Intent to Build a MiniBooNE Near Detector: BooNE W.C. Louis & G.B. Mills, FNAL PAC, November 13, 2009 Louis BooNE Physics Goals MiniBooNE Appearance & Disappearance Results Global 3+1 Fits to World Data Preliminary MINOS Results Mills BooNE (New Detector or Moving MiniBooNE) Appearance Sensitivities Disappearance Sensitivities Conclusions

1. Search for e & e appearance and  &  disappearance with high sensitivity at ~1 eV 2 mass scale. 2. Search for differences between neutrinos & antineutrinos (CP & CPT violation). 3. Search for sterile neutrinos by comparing NC   interactions. 4. Determine whether the MiniBooNE neutrino low-energy excess is due to oscillations or to a new background of importance to NOvA and LBNE. 5. Determine whether there is large  disappearance, as suggested by global 3+1 fits to world antineutrino data. 6. Determine whether there is e appearance consistent with LSND. BooNE Physics Goals

Keep L/E same as LSND while changing systematics, energy & event signature P    e  sin   sin   m  L  Booster K+K+ target and horndetectordirtdecay regionabsorber primary beamtertiary beamsecondary beam (protons)(mesons)(neutrinos)    e   Order of magnitude higher energy (~500 MeV) than LSND (~30 MeV) Order of magnitude longer baseline (~500 m) than LSND (~30 m) MiniBooNE’s Design Strategy

MiniBooNE  e appearance data show a low-energy excess A.A. Aguilar-Arevalo et al., PRL 102, (2009) Excess from MeV = events 6.46E20 POT

N N’   Other PCAC N N’   Axial Anomaly NN’  Radiative Delta Decay (G 2  S ) N N’  Backgrounds: Order (G 2  s ), single photon FS So far no one has found a NC process to account for the, difference & the low-energy excess. Work is in progress: R. Hill, arXiv: Jenkins & Goldman, arXiv:  Dominant process accounted for in MC!

Preliminary for 4.863E20 POT (~50% increase in POT!) Excess from MeV = 11.4 ± 9.4 ± 11.2 events MiniBooNE  e appearance data are inconclusive at present but are consistent so far with LSND New!

Preliminary e Data with E20 POT Event excess has increased with new data. Additional data will double #POT and determine whether this excess is real. E >200 MeVE >475 MeV Data Events Bkgd Events Excess Events Excess at b.f (1.78  ) (1.92  ) LSND Expect.~29.7~21.8   null 32.3/18 DF (2%)27.5/15 DF (2%)   bf 21.8/16 DF (15%)18.4/13 DF (14%)  m 2 bf 4.42 eV eV 2 sin   bf

G. Karagiorgi et al., arXiv: Best 3+1 Fit:  m 41 2 = eV 2 sin 2 2   e =   = 87.9/103 DOF Prob. = 86% Predicts    e disappearance of sin 2 2   ~ 35% and sin 2 2  ee ~ 4.3% 3+1 Global Fit to World Antineutrino Data (without new antineutrino data)

3+1 Global Fit to World Antineutrino Data w/o LSND

MiniBooNE Neutrino & Antineutrino Disappearance Limits Improved results soon from MiniBooNE/SciBooNE Joint Analysis! A.A. Aguilar-Arevalo et al., PRL 103, (2009) * * Global best fit

Initial MINOS  Disappearance Results Expect  disappearance above 10 GeV for LSND neutrino oscillations.

Conclusion MiniBooNE observes an unexplained excess at low energies, which could be due to oscillations, sterile decay, or to NC  scattering. No large low-energy excess is observed so far in antineutrino mode. All antineutrino data fit well to a simple 3+1 model. (LSND is alive & well!) However, there is tension between neutrino & antineutrino data. (CPT Violation?) The global fit to the world antineutrino data predicts large  disappearance, which will be tested soon by MINOS and SciBooNE/MiniBooNE. BooNE, which involves building a near MiniBooNE detector, will be able to exploit the data taken in the far detector (the hard part!) and determine whether there is large  disappearance and whether the MiniBooNE low-energy excess is due to oscillations. Thorough understanding of this short-baseline physics is of great importance to long-baseline oscillation experiments. BooNE would be a small investment to ensure their success!

BooNE A near detector at 200 meters from the BNB target  Reduce low-energy excess systematic errors in Near/Far comparison  potential 6  sensitivity from statistical errors: 128  20(stat)  38(sys)  Accumulate neutrino and antineutrino data at x7 rate!  Full samples in ~1 year (2 x 1x10 20 pot)  Capitalize on the 10 year investment in MiniBooNE data  Determine L/E dependence of low energy excess  Search with high sensitivity for e & e appearance and  &  disappearance  Special runs to check systematic effects (absorber down, horn off, etc.)

New Location at 200 meters from BNB Target BNB Target Hall Far Position Near Position BNB beam

The MiniBooNE Low-Energy Excess with BooNE  Background case: the near detector will observe the same fractional excess as the far detector  Neutrino oscillations at low  m 2 : the near detector will observe no excess and the excess in the far detector, assuming a 2.5% systematic error, will be: (3.0  ) (current MiniBooNE measurement) (4.2  ) (near/far comparison with 1x10 20 ND) (5.6  ) (with >> 1x10 20 ND) (in a nutshell)

Neutrino Fluxes at Near and Far Locations

µ Charged Current QE Event Rates Near and Far Quasi elastic event rates

e Appearance Sensitivity with Near/Far Comparison Near/Far comparison sensitivity  Near location at 200 meter 1x10 20 pot <1 yr of running  Full systematic error analysis Flux, cross section, detector response  Assumes identical detectors in Near/Far comparison Near/Far 4  sensitivity similar to single detector 90% CL

e Appearance Sensitivity with Near/Far Comparison Near/Far comparison sensitivity  Near location at 200 meter 1x10 21 pot for FD 1x10 20 pot <1 yr for ND  Full systematic error analysis Flux, cross section, detector response  Assumes identical detectors in Near/Far comparison

µ and µ Disappearance Sensitivity with Near/Far Comparison With two identical detectors, many of the systematic errors will cancel, giving excellent disappearance sensitivity *

BooNE Disappearance Discovery Potential Allowed region for signal:  m 2 =0.915 eV 2 and sin 2 2   =0.35 (after G. Karagiorgi et al., arXiv: )

Options for Near BooNE Detector New Detector (two detectors run concurrently) –Construct brand new detector at 200 meters (~8M$) Move old detector –Transport existing MiniBooNE detector (~80 tons) to new location 200 meters from BNB target (~4M$) –OR Dismantle existing MiniBooNE detector, reuse PMTs and electronics to construct a new detector at 200 meters. (~4M$) –MicroBooNE could reduce it’s costs by using the MiniBooNE enclosure 22

BNB Beam Stability The MiniBooNE neutrino rate per pot has been exceptionally stable horn and target changed in 2004 polarity changed in 2005, 2007, and 2008

BooNE is Complementary to MicroBooNE & SciBooNE MicroBooNE will determine whether the MiniBooNE low-energy is due to electrons or gammas MicroBooNE will not be able to determine the L/E dependence of the low-energy excess or search for disappearance MicroBooNE statistics will be too low for antineutrino appearance SciBooNE/MiniBooNE joint analysis will make an initial search for disappearance with two detectors; however, the statistical & systematic error will be much larger than BooNE SciBooNE/MiniBooNE will not be able to improve the search for appearance

Conclusion A BooNE near detector at 200 meters with one year of running would resolve whether or not the low-energy excess is due to an oscillation-like phenomena at the ~ 4 sigma level It would also provide a high statistics, low systematic error µ and µ disappearance measurement in a region not yet covered by other experiments The timing of the project is ideal for post-antineutrino running in the BNB We are studying whether it is better to move the existing detector or to construct a new one (cost vs. performance)

Backup Slides

A.A. Aguilar-Arevalo et al., PRL 103, (2009) MiniBooNE e appearance data are inconclusive at present but are consistent so far with LSND Excess from MeV = -0.5 ± 7.8 ± 8.7 events 3.4E20 POT

MiniBooNE e appearance sensitivity

MiniBooNE e appearance data are inconclusive at present but are consistent so far with LSND Excess from MeV = 10.2 ± 15.8 events Preliminary for 4.863E20 POT

Preliminary e Fits with E20 POT E >200 MeVE >475 MeV LSND allowed region LSND allowed region

BooNE Rough Cost & Schedule Estimate Common costs whether building or moving (FY10-FY11) New Hall Engineering & Construction * $1894K Moving MiniBooNE: (FY10-FY12) Engineering and Transport$1500K Superstructure Removal$500k Total$3894K New Detector (FY10-FY13) Tank & Support Structure * $1065K PMTs$1759K Electronics/DAQ$512K Oil$1429K Calibrations + Miscellaneous$610K Total$7269K * MiniBooNE costs + 3%/year+30%contingency, no G&A or DOE “project costs”

BooNE Appearance Sensitivity e Appearance Sensitivity

G. Karagiorgi et al., arXiv: Best 3+1 Fit:  m 41 2 = 0.19 eV 2 sin 2 2   e =   = 90.5/90 DOF Prob. = 46% Predicts    e disappearance of sin 2 2   ~ 3.1% and sin 2 2  ee ~ 3.4% 3+1 Global Fit to World Neutrino Data

Lift of 260 ton Generator 34 Transporting 550 ton Coker Drum from ship to crane hook With oil removed, MiniBooNE is about 80 tons: 750 ton crane