MiniBooNE: Current Status Outline Physics motivation Beamline performance Detector performance Preliminary results Conclusions Fernanda G. Garcia, Fermilab BD seminar, October 7, 2003

LSND: Evidence for (   e ) Beam related backgrounds Excess of events: 87.9  22.4  6.0 Expectation for oscillations Data points after background subtraction

Neutrino oscillation: allowed regions 3 allowed regions - neutrinos from the sun - neutrinos from atmosphere - neutrinos from accelerators But...with 3 active 's there are only 2 independent  m 2  m 2 ~10 -(0-1)  m 2 ~3x10 -3  m 2 ~10 -(4- 5)

How do we fix this? 3+1 model 2+2 model If neutrinos have mass Physics beyond the Standard Model Sterile neutrinos ? ( can not interact weakly via W or Z, but standard might oscillate to s )  LSND primarily v s  Atmospheric, solar, and LSND mixtures of s LSND Solar Atm Sola r At m       Mass  CPT ? Atm Solar Atm, LSND Kamland This model fits all present data (m  m ) Barenboim et.al. (Phys.Lett.B534:106,2002)

Other experiments explored this region 90% excluded region from other experiments Karmen accelerator based Bugey reactor based (  e disappearance)  m 2  0.2  10 eV 2

Actually, there are space left Combined analysis LSND and Karmen There are still allowed regions left Needs confirmation MiniBooNE

MiniBooNE Experiment High statistics 10 x more than LSND Different systematics different backgrounds and event signatures High flux  beam with well understood e component MI Tevatron Main Injector Booster Goal: test LSND allowed region with 5  sensitivity

BooNE: Booster Neutrino Experiment Y. Liu, I. Stancu Alabama S. Koutsoliotas Bucknell E. Hawker, R.A. Johnson, J.L. Raaf Cincinnati T. Hart, E.D. Zimmerman Colorado Aguilar-Azevedo, L. Bugel, J.M. Conrad, J. Formaggio, J. Link, J. Monroe, D. Schmitz, M.H. Shaevitz, M. Sorel, G.P. Zeller Columbia D. Smith Embry Riddle L. Bartozek, C. Bhat, S.J. Brice, B.C. Brown, D.A. Finley, B.T. Fleming, R. Ford, F.G. Garcia, P. Kasper, T. Kobilarcik, I. Kourbanis, A. Malensek, W. Marsh, P. Martin, F. Mills, C. Moore, P.J. Nienaber, E. Prebys, A.D. Russell, P. Spentzouris, R. Stefanski, T. Williams Fermilab D.C. Cox, A. Green, H.O. Meyer, R. Tayloe Indiana G.T. Garvey, C. Green, W.C. Louis, G. McGregor, S. McKenney, G.B. Mills, V. Sandberg, B. Sapp, R. Schirato, R. Van de Water, D.H. White Los Alamos R. Imlay, W. Metcalf, M. Sung, M.O. Wascko Louisiana State J. Cao, Y. Liu, B.P. Roe Michigan A.O. Bazarko, P.D. Meyers, R.B. Patterson, F.C. Shoemaker, H.A. Tanaka Princeton First Phase: MiniBooNE ● Single detector     e appearance  L/E  1m/MeV

MiniBooNE layout horn and targetdecay region absorber dirt (~ 450m ) detector protonsmesonsneutrinos different backgrounds different systematics 10x more statistics December 1997: proposal submitted August 2002: started taking data

Booster...way to go! Booster delivers high intensity 8 GeV protons to support FNAL physics program Booster: 8 GeV synchrotron with 15 Hz resonant magnet ramps provides 1.6  s beam pulses Stacking 5x10 12 protons/cycle Collider protons 3-4x10 11 protons/coal. bunch SY120 ~ 0.4x10 12 protons/cycle (commissioning phase) MI development studies MiniBooNE 3  4x10 12 protons/cycle NUMI 2.5x10 13 protons/cycle Currently accelerates  5x10 12 protons/pulse

... but it can only go so far Plan Current Protons per Booster batch 5.0 x  4x10 12 Rep Rate (Hz)  3 Beam power (MW) Protons per year 5.0 x x10 20 Important improvements underway collimator rearrangement of the extraction area large apperture RF cavities better monitoring We are optimistic we will reach our design rate/intensity by Jan'04 Radiation loss is a big concern MiniBooNE

The 8 GeV beamline The Booster primary beam is extracted from the MI-8 beamline at 8 GeV kinetic energy. The 8 GeV beamline transport the proton beam from MI-10 to the MiniBooNE target.

8 GeV MiniBooNE beamline beam elements beam monitoring

Beamline lattice Final focus Arc I. A main injector pulsed magnet deflects the MB batches into the MB channel. II. Quads capture the beam and focus it for transport through the berm pipe. III. Quads match the beam into the FODO cells at the arc. IV. Final focusing section. I. and II. III. IV. Q861 Q864 Q866 Q868 Q870 Q874 Q862 Q865 Q867 Q869 Q871 Q873 Q875 I./II. III. IV. Drift

Beam Operations MiniBooNE Beam Permit List Beam trip frequency Booster provides beam to MiniBooNE when there is no MI beam request. Typically MI is stacking, so there can be up to 10 $1D cycles trailer hitched to stacking cycles to provide beam to MiniBooNE while MI is ramping. Running mode: Autotune: automated software application which allows to correct deviations of the beam from the nominal trajectory.

The target system   +   +       K L 0       +  e + e  K +   0 e + e K L 0  - e + e - 71 cm long Be target (3/8” diameter) - Resides inside the horn - The target was calibrated for  production at HARP (CERN) (20.6 million triggers)  The beam strikes a beryllium target producing Operating temperature  60  C (current rate) Target has performed well Spare target is being assembled

Outstanding horn performance Current: 170 KA Rep rate: 5 Hz Design lifetime: 200 million pulses Current: 40 million pulses in situ Toroidal magnetic field focuses positive particles (  mode) Can switch polarity to focus negative particles ( mode) Horn operation has been consistently reliable Precautions: horn does not pulse when switch is taken or loose beam permit

Neutrino flux at the detector 8 GeV protons on target yields a high flux of  Expected intrinsic e flux is small (0.3  contamination)

Understanding beam backgrounds Intrinsic e 's from  decays Signal and background behave differently by varying the length of decay pipe  from  decays  L e from  decays  L 2 Backgrounds are mis-id of  's and  's and intrinsic e in the beam Intrinsic e 's from Kaons decay (K +,K L )  Little Muon Counter

Little Muon Counter (LMC) (off-axis (7  muon spectrometer) Monte Carlo muon momentum at 7° (GeV)  from   from K 19 ns Data from LMC PMT hits  time beam hit the target (ns) ➔ Kaon decays produce higher energy wide angle muons than pion decays ➔ scintillating fiber tracker temporary scintillator paddle commission data acquisition

The MiniBooNE Detector

MiniBooNE Detector ● 12 meters spherical steel tank ● 250,000 gallons of mineral oil (  800 tons) ● 1280 PMT's in the main region (5.75 meters) ● 240 PMT in veto region ● Neutrino interactions in oil produce light (Cherenkov and scintillation) ● We measure time and charge for each tube

Event identification michel e - from stopped  decay after   interaction  from   interaction  0 from   interaction size=charge, color=time Pattern of hit tubes (with energy and time information) allows for the separation of different event types.

Calibration: laser system   new PMT old PMT 4 flasks at different location in the tank fed by a optical fiber from laser Measure: PMT charge and time response and oil attenuation length laser modeling other sources of “late light”

Calibration: muon tracker system Four layers of scintillator tracker above the tank provide direction of the cosmic ray muon 7 optically isolated scintillator cubes give position measurement of the stopping muons and decay electrons

Energy calibration: cosmic ray Using decay electrons from cosmic muons to determine energy scale Michel electron energy spectrum The endpoint indicates 15% energy resolution Data and MC comparison Cosmic michel data Analytic curve

DAQ and Trigger Average trigger rate ~23 Hz Beam rate 2-3 Hz DAQ uptime ~ 99% Variety of internal triggers are implemented

MiniBooNE Operation First beam on target delivered in August' days of running (08/24/02 09/02/03) ~ 1.5 x protons on target (160,000 neutrino candidates)  260 beam spills/event Neither beamline nor detector experienced any major failure during this first year of data taking

Events are seen inside the beam window triggered on signal from Booster DAQ reads out for 19.2  s around the 1.6  s beam window backgrounds: cosmic muons decay electrons no sophisticated analysis is needed to see events over the background with simple cuts one can reduce the no-beam background by ~ 10  3

Reconstruction: energy and direction Events sample contain both Charge Current and Neutral Current events Preliminary Reconstructed visible energy (MeV) Cuts: Tank hits > 200 Veto hits < 6 Radius < 500 cm beam window Preliminary cos 

Fine beam timing A resistive wall monitor measures the beam time profile just upstream the target Discriminated signal sent to DAQ 19ns We can measure the booster bunch time in neutrinos!

 e appearance sensitivity intrinsic  e  1500 mis-identified   500 mis-identified  0  500 LSND    e signal  1000 preliminary estimates background and signal cover LSND allowed region at 5  update estimates coming expect results in 2005 Blind  e appearance analysis

Neutral Current  0 production  (p/n)    0 (p/n) Resonant: Coherent:  C   0 C  0  2 rings perform 2 ring fit on all events 2 rings with energy > 40 MeV each sensitive to production mechanism coherent is more forward-peaked

Conclusions MiniBooNE is taking data and is doing well steadily taking data 1.5 x pot so far ( 15  of the 1x10 21 ) beamline is working well, but still need more intensity detector and reconstruction algorithms are working well

Backup slides

Detector Operational ● PMT's Total of 12 dead PMT's, all during initial running Main tubes dark noise ~ 1 kHz ● Electronics 99% channels operational ● Detector livetime Neutrino running (beam on) ~99% All data taking/total time ~ 91%

 easured and predicted changes of central trajectory along beamline Calculated beam envelope with measurements overlayed 8 GeV MiniBooNE beam line

Laser Flasks   Single pe timing resolution new PMT old PMT Time (ns) Old PMT new PMT Time offset constants Time slewing constants Low charge pulses need additional time correction These values are applied so calibration time of laser hits is uniform across all tubes Good agreement with bench tests

What do we know about low energy neutrinos cross sections?  We collected ALL possible low energy neutrino data to check cross sections model and kinematics Check rates for various interactions