BNL Very Long Baseline Neutrino Oscillation Expt.

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1 Mary Bishai, BNL 1 p.1/14 BNL Very Long Baseline Neutrino Oscillation Expt. Next Generation of Nucleon Decay and Neutrino Detectors 8/4/25 Mary Bishai mbishai@bnl.gov Brookhaven National Lab.

2 Mary Bishai, BNL 2 p.2/14 Outline The case for a very long baseline ν experiment Highlights from BNL s Conceptual Design Report BNL physics sensitivies for L = 254 km and L = 129 km Conclusions

3 Mary Bishai, BNL 3 p.3/14 Why a Very Long Baseline? Sensitivity to atmospheric ( m 2 32 ) AND solar ( m2 21 ) oscillation scales Verify oscillation behaviour by observing multiple nodes. Multiple nodes = higher precision. Resolution of E νµ < 1GeV/c 2 dominated by Fermi motion maximize L = O(1) km Higher energies = larger crosssections Energy (GeV) Oscillation Nodes for m 2 =.25 ev FNAL-SOUDAN π/2 3π/2 BNL-HOMESTAKE 5π/2 Fermi motion dominated Baseline (km) BNL 1MW, L = 254 km, 5 kt 1% resol on m 2 32 and sin2 2θ 23

4 Mary Bishai, BNL 4 p.4/14 Sensitivity to δ cp & sign( m 32 ) Matter effects enhance (suppress) ν µ ν e oscillation probability for m 3 > m 2 > m 1 (m 2 > m 1 > m 3 ). Effect largest for E ν > 3 GeV/c 2 For 1 < E ν < 3 GeV/c 2 appearance spectrum is sensitive to δ cp Marciano (hep-ph/18181): CP asymmetry in ν µ ν e, A, grows with L, flux at far detector goes as 1/L 2. FOM = A 2 N ν /(1 A 2 ) is constant. Probability ν µ ν e Oscillation BNL-HS 254 km, matter effects sin 2 2θ (12,23,13) = (.86, 1.,.4) m (21,31) 2 = (7.3e-5, 2.5e-3) ev 2 Neutrino Running m 32 2 >, δ CP = 45 o m 32 2 >, δ CP = o m 32 2 <, δ CP = o E ν (GeV)

5 Mary Bishai, BNL 5 p.5/14 Separating Multiple ν µ ν e Effects Need a broadband beam with E ν = 1 to 6 GeV to resolve degeneracies energy sin 2 2θ 13 m 2 32 δ CP = θ 23 (GeV) > (>, < ) ( π 4, π 4 ) (< π 4, > π 4 ) ν 1.2,,, ,,, > 2.2,,, ν 1.2,,, ,,, > 2.2,,, For 3 generations we do not need ν!

6 Mary Bishai, BNL 6 p.6/14 BNL baselines The US is 45 km coast-to-coast. Brookhaven National Lab is located on the eastern coast ideal for O(2) km baselines. BNL-Homestake mine = 254 km BNL-Henderson mine = 27 km

Mary Bishai, BNL 7 p.7/14 BNL Conceptual Design Report BNL-7321-24-IR available at http://raparia.sns.bnl.gov/nwg ad/ AGS = highest intensity proton beam in the world. E p = 28 GeV.

7 Mary Bishai, BNL 7 p.7/14 BNL Conceptual Design Report BNL IR available at ad/ AGS = highest intensity proton beam in the world. E p = 28 GeV. Upgrade AGS intensity from ppp to ppp. +.5 Hz rep. rate to 2.5 Hz 1 MW To achieve 2.5 Hz rep rate: Upgrade 2 MeV Linac to 4 MeV a la Fermilab c Replace booster with 1 GeV superconducting linac (SCL) using SNS 85 MHz technology.

8 Mary Bishai, BNL 8 p.8/14 Getting the beam to Homestake Beam needs to point downwards at 11.3 to reach detector at 254 km Build a hill instead of a tunnel! = hadrons above water Civil engineering costs (including linac gallery) = FY 4 $ 69 M

9 Mary Bishai, BNL 9 p.9/14 BNL 1MW ν beam cost estimate Total direct cost is FY 4 $ M. Total estimated cost is FY 4 $ 46.9 M (including 3% contingency)

10 Construction Schedule Mary Bishai, BNL 1 p.1/14

11 Mary Bishai, BNL 11 p.11/14 Physics potential of VLB MC simulation with fermi motion, detector resolution and physics backgrounds for L = 254 and 129 km. M. Diwan, hep-ex/4747: BNL beam L = 254 km BNL beam L = 129 km ν µ disappearance ν µ disappearance Events/bin 25 BNL to Homestake 254 km sin 2 2θ 23 = 1. Events/bin 1 FNAL to Homestake 129 km sin 2 2θ 23 = 1. m 2 32 = 2.5e-3 ev2 Beam 1 MW, Det..5 MT, Run 5e7 sec 2 m 2 32 = 2.5e-3 ev2 8 Beam 1 MW, Det..5 MT, Run 5e7 sec 15 No oscillations: 1329 evts With oscillations: 6535 evts 6 No oscillations: 515 evts With oscillations: 235 evts Reconstructed ν µ Energy (GeV) Reconstructed ν µ Energy (GeV) ν e APPEARANCE ν e APPEARANCE Events/bin 1 Events/bin 25 FNAL-HS 129 km sin 2 2θ ij (12,23,13) =.86/1./.4 m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW,.5 MT, 5e7 sec BNL-HS 254 km sin 2 2θ ij (12,23,13) =.86/1./.4 m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW,.5 MT, 5e7 sec CP 135 o : 591 evts CP 45 o : 45 evts CP -45 o : 299 evts Tot Backg.: 146 evts ν e Backg.: 7 evts CP 135 o : 1711 evts CP 45 o : 1543 evts CP -45 o : 1114 evts Tot Backg.: 566 evts ν e Backg.: 272 evts Reconstructed ν Energy (GeV) Reconstructed ν Energy (GeV)

12 Mary Bishai, BNL 12 p.12/14 Limits after ν running 9% confidence level error contours. Statistical + 1% systematic errors: BNL beam L = 254 km Regular hierarchy ν and Antiν running BNL beam L = 129 km Regular hierarchy ν and Antiν running δ CP (deg.) MW ν, 2 MW Anti-ν, 5kT, BNL-HS 254km 9% C.L. intervals for 32 test points δ CP (deg.) MW ν, 2 MW Anti-ν, 5kT, FNAL-HS 129km 9% C.L. intervals for 32 test points Sin 2 2θ Sin 2 2θ 13 If no ν e observed limit sin 2 2θ 13.3 independant of δ cp

13 Mary Bishai, BNL 13 p.13/14 Appearance of ν e when θ 13 = P (ν µ ν e ) ( m 2 21 L 4E If sin 2 2θ 13 is small δ cp measurement not possible BUT observation of ν e appearance is still possible from the current value of the solar parameters ) 2 cos 2 θ 23 sin 2 2θ 12 Events/bin BNL beam L = 254 km ν e APPEARANCE BNL-HS 254 km sin 2 2θ ij (12,23,13) =.86/varied/. m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW,.5 MT, 5e7 sec Resolving Θ 23 ambiguity With Θ 13 = 1 deg. Off axis beam Θ 23 =35 o : 212 evts Θ 23 =45 o : 181 evts Θ 23 =55 o : 151 evts Better S:B off axis capability is built into baseline BNL proposal Tot Backg.: 9 evts ν e Backg.: 52 evts Reconstructed ν Energy (GeV) Only feasible with the longer baseline (254 km) because of better S:B

14 Mary Bishai, BNL 14 p.14/14 Summary of BNL studies: A very long baseline experiment can address both the solar and atmospheric oscillation scales. Very precise measurements of m 2 32 and sin2 θ 23 can be acheived at either 129 or 254 km baseline. Very good bounds on θ 13 from either baseline Longer baseline = more sensitivity to ν e appearance if θ 13 too small. If sin 2 2θ 13 not too small then δ cp can be determined from ν running only. With the longer baseline = larger mass effects = better resolution of mass heirarchy and easier extraction of δ cp. Sensitivity to new physics and further improvements in δ cp measurement can then be achieved with ν running.

BNL Very Long Baseline Neutrino Oscillation Expt.

Mary Bishai, BNL 1 p.1/36 BNL Very Long Baseline Neutrino Oscillation Expt. Next Generation of Nucleon Decay and Neutrino Detectors 8/04/2005 Mary Bishai mbishai@bnl.gov Brookhaven National Lab. Mary Bishai,