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 eV2 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 importanceto 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

PesinsinmL

Booster

K+

target and horn detectordirt decay region absorber

primary beam tertiary beamsecondary beam

(protons) (mesons) (neutrinos)

e

Order of magnitudehigher energy (~500 MeV)

than LSND (~30 MeV)

Order of magnitudelonger baseline (~500 m)

than LSND (~30 m)

MiniBooNE’s Design Strategy

MiniBooNEe appearance data show a low-energy excess

A.A. Aguilar-Arevalo et al., PRL 102, 101802 (2009)

Excess from 200-475 MeV = 128.8+-20.4+-38.3 events

6.46E20 POT

NN’

ZV0

'

Other PCAC

NN’

ZA0

'

Axial Anomaly

'

N N’

Radiative Delta Decay

(G2S)

N N’

ZA0

'

Backgrounds: Order (G2s) , single photon FS

Z0

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:0905.0291

Jenkins & Goldman, arXiv:0906.0984

Dominant processaccounted for in MC!

Preliminary for 4.863E20 POT (~50% increase in POT!)

Excess from 200-475 MeV = 11.4 ± 9.4 ± 11.2 events

MiniBooNEe appearance data are inconclusive at present but are consistent so far with LSND

New!

Preliminary e Data with 4.863 E20 POT

Event excess has increased with new data. Additional data willdouble #POT and determine whether this excess is real.

E>200 MeV E>475 MeV

Data Events 225 126Bkgd Events 201.6 114.1Excess Events 23.4+-22.6 11.9+-16.4Excess at b.f. 41.6+-23.4 (1.78) 32.2+-16.8 (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%)m2

bf 4.42 eV2 4.64 eV2

sinbf0.0058 0.0058

G. Karagiorgi et al.,arXiv:0906.1997

Best 3+1 Fit:m41

2 = 0.915 eV2

sin22e = 0.0043 = 87.9/103 DOFProb. = 86%

Predicts e

disappearance of sin22~ 35% andsin22ee ~ 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, 061802 (2009)

*

*

Global best fit

Initial MINOS Disappearance Results

Expect disappearance above10 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: 12820(stat)38(sys)Accumulate neutrino and antineutrino data at x7 rate!

Full samples in ~1 year (2 x 1x1020pot)

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 PositionB

NB

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 m2:

the near detector will observe no excess and the excess in the far detector, assuming a 2.5% systematic error, will be:

128.8+-20.4+-38.3 (3.0 ) (current MiniBooNE measurement)

128.8+-28.8+-10.4 (4.2 ) (near/far comparison with 1x1020pot @ ND)128.8+-20.4+-10.4 (5.6 ) (with >> 1x1020pot @ ND)

(in a nutshell)

Neutrino Fluxes at Near and Far Locations

µ Charged Current QE Event Rates Near and Far

Quasi elastic event rates

840

786CCQE

MeV FarE

MeV Near

e Appearance Sensitivity with Near/Far Comparison

Near/Far comparison sensitivity

Near location at 200 meter

1x1020 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 detector90% CL

e Appearance Sensitivity with Near/Far Comparison

Near/Far comparison sensitivity

Near location at 200 meter

1x1021 pot for FD1x1020 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: m2 =0.915 eV2 and sin22=0.35

(after G. Karagiorgi et al., arXiv:0906.1997)

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-energyis due to electrons or gammas• MicroBooNE will not be able to determine the L/E dependenceof 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 searchfor 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, 111801 (2009)

MiniBooNE e appearance data are inconclusive at present but are consistent so far with LSND

Excess from 200-475 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 200-475 MeV = 10.2 ± 15.8 events

Preliminary for 4.863E20 POT

Preliminary e Fits with 4.863 E20 POT

E>200 MeV E>475 MeV

LSND allowedregion

LSND allowedregion

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 e Appearance Sensitivity

G. Karagiorgi et al.,arXiv:0906.1997

Best 3+1 Fit:m41

2 = 0.19 eV2

sin22e = 0.031 = 90.5/90 DOFProb. = 46%

Predicts e

disappearance of sin22~ 3.1% andsin22ee ~ 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