BNL Very Long Baseline Neutrino Oscillation Expt.

Size: px

Start display at page:

Download "BNL Very Long Baseline Neutrino Oscillation Expt."

Evan Webster
5 years ago
Views:

1 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.

2 Mary Bishai, BNL 2 p.2/36 Outline The case for a very long baseline ν experiment Highlights from BNL s Conceptual Design Report Physics sensitivies for L = 2540km and L = 1290 km Conclusions

3 THE CASE FOR A SUPER NEUTRINO BEAM Mary Bishai, BNL 3 p.3/36

4 Mary Bishai, BNL 4 p.4/36 Why a Very Long Baseline? Sensitivity to atmospheric ( m 2 32 ) AND solar ( m2 21 ) oscillation scales Verify oscillation behaviour by observing multiple nodes Resolution of E νµ < 1GeV/c 2 dominated by Fermi motion maximize L = O(1000) km Higher energies = larger crosssections Very long baseline = multiple node pattern is detectible for all m 2 32 range. More nodes = higher precision. Energy (GeV) Oscillation Nodes for m 2 = ev FNAL-SOUDAN π/2 3π/2 BNL-HOMESTAKE 5π/2 Fermi motion dominated Baseline (km)

5 Mary Bishai, BNL 5 p.5/36 VLB Disappearance Sensitivity For a BNL-Homestake 2540 km baseline: Test point for ν µ disapp Test point for Anti-ν µ disapp m 32 2 ev Small oval is for BNL-HS 90 % C.L. contours Stat. + Syst. m 32 2 ev Small oval is for BNL-HS 90 % C.L. contours Stat. + Syst MINOS 90 % SuperK 90 % MINOS 90 % 2003 SuperK 90 % Sin 2 2θ Sin 2 2θ 23 1% resol on m 2 32 and sin2 2θ 23 if detector energy scale uncert 1%

6 Mary Bishai, BNL 6 p.6/36 VLB ν µ ν e Sensitivity Matter effects in two flavor oscillations: In neutrino oscillations with θ 13 0, matter effects change ν µ ν e oscillation probability. More matter = larger effects Marciano (hep-ph/ ): 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 P(ν µ ν e ) GeV neutrino, vacuum numu cp=90 numu cp=45 numu cp=0 anumu cp=45 anumu cp=90 SK best fit LMA-I sin 2 (2θ) 13 = FOM independent of baseline Brett Viren, bv@bnl.gov, 06/04/2004 Baseline (km)

7 Mary Bishai, BNL 7 p.7/36 Sensitivity to δ cp & sign( m 32 ) Matter effects enhance (suppress) ν µ ν e oscillation probability for E ν > 3 GeV/c 2 if m 3 > m 2 > m 1 (m 2 > m 1 > m 3 ) For 1 < E ν < 3 GeV/c 2 appearance spectrum is sensitive to δ cp Probability ν µ ν e Oscillation BNL-HS 2540 km, matter effects sin 2 2θ (12,23,13) = (0.86, 1.0, 0.04) m (21,31) 2 = (7.3e-5, 2.5e-3) ev 2 Neutrino Running m 32 2 > 0, δ CP = 45 o m 32 2 > 0, δ CP = 0 o m 32 2 < 0, δ CP = 0 o E ν (GeV) Enhancement at < 2 GeV is that expected from solar parameters.

8 Mary Bishai, BNL 8 p.8/36 Separating Multiple ν µ ν e Effects energy sin 2 2θ 13 m 2 32 δ CP = θ 23 (GeV) > 0 (> 0, < 0) ( π 4, π 4 ) (< π 4, > π 4 ) ν 0 1.2,,, ,,, > 2.2,,, ν 0 1.2,,, ,,, > 2.2,,, Need a broadband beam with E ν = 1 to 6 GeV For 3 generations we do not need ν!

9 THE CASE FOR BROOKHAVEN AS THE SUPER BEAM FACILITY Mary Bishai, BNL 9 p.9/36

10 Mary Bishai, BNL 10 p.10/36 BNL baselines The US is 4500 km coast-to-coast. Brookhaven National Lab is located on the eastern coast ideal for O(2000) km baselines. BNL-Homestake mine = 2540 km BNL-Henderson mine = 2700 km

BNL accelerates 1.5 GeV/c protons from the Booster up to 33 GeV/c.

11 Mary Bishai, BNL 11 p.11/36 The AGS as a proton source The Alternating Gradient Synchrotron at BNL accelerates 1.5 GeV/c protons from the Booster up to 33 GeV/c. Typical intensity achieved for slow extracted beam is protons at a rep rate of 0.5 Hz the most intense proton beam in the world

12 Mary Bishai, BNL 12 p.12/36 BNL ν beam spectrum Detailed simulation of a 28 GeV proton beam on a graphite target with a wideband focusing horn. Beam can be run in either neutrino or anti-neutrino mode. BNL Wide Band. Proton Energy = 28 GeV nu/gev/m 2 /POT at 1 km Distance = 1 km ν µ A combination of neutrino and anti-neutrino running will constrain sin 2 θ ν e ν e /ν µ = E ν (GeV) AGS 28 GeV protons will produce a spectrum of E ν = 1 to 10 GeV/c 2 Well matched to baseline 2000 km

13 Mary Bishai, BNL 13 p.13/36 BNL Conceptual Design Report BNL IR available at ad/

14 Mary Bishai, BNL 14 p.14/36 AGS MW Beam Requirements Very long baseline = low ν flux at the far detector need 1-2 MW beam and megaton detectors present AGS 1MW 2 MW Total power (MW) Beam Energy (GeV) Rep. rate Avg. current (µa) Avg. circulating current (A) No. of bunches at extraction Protons per fill AGS ONLY: upgrade cost = FY 04 $ 70.6 M To increase rep rate from replace booster.

15 Mary Bishai, BNL 15 p.15/36 Super Conducting Linac Linac design is driven by lenght constrain = 120m. We need a GeV linac to replace booster. A 1 GeV proton SCL for the Spallation Neutron Source has already been built High Intensity Source plus RFQ 200 MeV Drift Tube Linac 200 MeV 400 MeV Superconducting Linacs 800 MeV SCL BOOSTER 1.2 GeV To Target Station SNS AGS 1.2 GeV 28 GeV 0.4 s cycle time (2.5 Hz) 0.2 s 0.2 s To RHIC RF frequency(mhz) 805 & Accelerating gradient (MeV/m) Cells/cavity 8 6 Inner cavity space (cm) 32 & Warm to cold transition (cm) 30 75

16 Mary Bishai, BNL 16 p.16/36 SCL vs SNS layout Cost estimate of this SCL = FY 04 $ 122M

17 Mary Bishai, BNL 17 p.17/36 Alternative SCL design SCL design requires development of new 1610 MHz cavities. BNL is costing an alternative design based on upgrading the existing 200 MeV Linac to 400 MeV using the FERMILAB upgrade technology completed in 1993: Replace 4/9 drift-tube linac (DTL) tanks with 805 MHz coupled-cavity linac (CCL) modules. CCL modules are smaller than DTL = will fit. The SCL can then accelerate up to 1.5 GeV using only SNS 805 MHz cavities.

18 Mary Bishai, BNL 18 p.18/36 Target and horn design Temperature rise per pulse in CC target is T = 270.

19 Target irradiation studies Mary Bishai, BNL 19 p.19/36

20 Horn irradiation studies Mary Bishai, BNL 20 p.20/36

21 Mary Bishai, BNL 21 p.21/36 Getting the beam to Homestake Beam needs to point downwards at 11.3 to reach detector at 2540 km Build a hill instead of a tunnel! = hadrons above water

22 Location of The Hill Mary Bishai, BNL 22 p.22/36

23 Mary Bishai, BNL 23 p.23/36 Elevation view of The Hill Civil engineering costs (including linac gallery) = FY 04 $ 69 M

24 Mary Bishai, BNL 24 p.24/36 BNL 1MW ν beam cost estimate Total direct cost is FY 04 $ M. Total estimated cost is FY 04 $ M (including 30% contingency)

25 Construction Schedule Mary Bishai, BNL 25 p.25/36

26 Mary Bishai, BNL 26 p.26/36 PHYSICS POTENTIAL OF BNL-HS (2540 km) and FNAL-HS (1290 km) VERY LONG BASELINE EXPT. M. Diwan, The Case for a Super Neutrino Beam. Conference proceedings of Heavy Quarks and Leptons, San Juan, Puerto Rico, June 1-June 5, 2004, hep-ex/

27 Mary Bishai, BNL 27 p.27/36 Raw Event Counts 1 (2) MW ν ( ν), 500 kt, L=2540km, sec. Strong ν e π 0 background rejection in Water Cherenkov detectors is very feasible - see next talk. CC ν µ N µ X (30050) NC ν µ N ν µ X (11540) CC ν e N e X 380 (106) QE ν µ n µ p (11868) NC elastic 4575 (3882) QE ν e n e p 84 (80) CC Single π (11872) NC Single π 7741 (5074) CC Two π (3336) NC Two π 3557 (1630) CC > 2 π 4882 (500) NC > 2 π 1729 (560) CC ν τ N τ X 110 (40) (depends on m 2 )

28 Mary Bishai, BNL 28 p.28/36 ν µ Disappearance Results for clean QE µ. MC includes fermi motion, detector resolution and non-qe backgrounds ν µ disappearance ν µ disappearance Events/bin 250 BNL to Homestake 2540 km sin 2 2θ 23 = 1.0 Events/bin 1000 FNAL to Homestake 1290 km sin 2 2θ 23 = 1.0 m 2 32 = 2.5e-3 ev2 Beam 1 MW, Det. 0.5 MT, Run 5e7 sec 200 m 2 32 = 2.5e-3 ev2 800 Beam 1 MW, Det. 0.5 MT, Run 5e7 sec 150 No oscillations: evts With oscillations: 6535 evts 600 No oscillations: evts With oscillations: evts Reconstructed ν µ Energy (GeV) Reconstructed ν µ Energy (GeV) Oscillation pattern in spectrum = low sensitivity to flux normalization Both baselines will determine m 2 32 and sin2 2θ 32 to 1%

29 Mary Bishai, BNL 29 p.29/36 ν e appearance (normal hierarchy) Longer baseline oscillation visible ν e APPEARANCE ν e APPEARANCE Events/bin 100 Events/bin 250 FNAL-HS 1290 km sin 2 2θ ij (12,23,13) = 0.86/1.0/0.04 m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW, 0.5 MT, 5e7 sec BNL-HS 2540 km sin 2 2θ ij (12,23,13) = 0.86/1.0/0.04 m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW, 0.5 MT, 5e7 sec CP 135 o : 591 evts CP 45 o : 450 evts CP -45 o : 299 evts Tot Backg.: 146 evts ν e Backg.: 70 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) Already assuming 10% background uncertainty More detailed discussion of background suppression in following talk

30 Mary Bishai, BNL 30 p.30/36 Sensitivity to δ cp (normal heirarchy) Resolution δ CP vs Sin 2 2θ 13 Resolution δ CP vs Sin 2 2θ 13 δ CP (deg.) ν µ Running Only δ CP (deg.) ν µ Running Only % C.L. 3 cntrs: STAT only % C.L. 3 cntrs: STAT only 0 STAT+10% SYST STAT+20% SYST 0 STAT+10% SYST STAT+20% SYST BNL-HS 2540 km sin 2 2θ ij (12,23,13) = 0.86/1.0/0.04, δ CP =45 o m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW, 0.5 MT, 5e7 sec -150 FNAL-HS 1290 km sin 2 2θ ij (12,23,13) = 0.86/1.0/0.04, δ CP =45 o m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW, 0.5 MT, 5e7 sec Sin 2 2θ Sin 2 2θ 13 Although CP resolution is independent of baseline Shorter baseline = systematics limited

31 Mary Bishai, BNL 31 p.31/36 Appearance of ν e when θ 13 = 0 If sin 2 2θ 13 is small δ cp measure- ν e APPEARANCE ment not possible BUT observation of ν e appearance is still possible from the current value of the solar parameters Events/bin BNL-HS 2540 km sin 2 2θ ij (12,23,13) = 0.86/varied/0.0 m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW, 0.5 MT, 5e7 sec Resolving Θ 23 ambiguity With Θ 13 = 0 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 Tot Backg.: 90 evts ν e Backg.: 52 evts baseline BNL proposal Reconstructed ν Energy (GeV) Only feasible with the longer baseline (2540 km) because of better S:B

32 Mary Bishai, BNL 32 p.32/36 ν e appearance (normal hierarchy) Lower cross-sections need 2 MW beam Anti-ν e APPEARANCE ν e APPEARANCE Events/bin Events/bin BNL-HS 2540 km sin 2 2θ ij (12,23,13) = 0.86/1.0/0.04 m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 2 MW, 0.5 MT, 5e7 sec BNL-HS 2540 km sin 2 2θ ij (12,23,13) = 0.86/1.0/0.04 m ij 2 (21,32) = 7.3e-5/2.5e-3 ev 2 1 MW, 0.5 MT, 5e7 sec CP -45 o : 422 evts CP 45 o : 357 evts CP 135 o : 263 evts Tot Backg.: 151 evts anti-ν e Backg.: 82 evts Bck and sig. including wrong-sign CP 135 o : 591 evts CP 45 o : 450 evts CP -45 o : 299 evts Tot Backg.: 146 evts ν e Backg.: 70 evts Reconstructed ν Energy (GeV) Reconstructed ν Energy (GeV) Mass hierarchy resolved to better than 10 σ after ν ν running. Sensitive to new physics

33 Limits after ν running 90% confidence level error contours with statistical and 10% systematic errors: Regular hierarchy ν and Antiν running Regular hierarchy ν and Antiν running MW ν, 2 MW Anti-ν, 500kT, BNL-HS 2540km 90% C.L. intervals for 32 test points δcp (deg.) MW ν, 2 MW Anti-ν, 500kT, FNAL-HS 1290km 90% C.L. intervals for 32 test points δcp (deg.) Sin 2 2θ Sin 2 2θ 13 If no νe observed limit sin 2 2θ Mary Bishai, BNL 33 p.33/36

34 Mary Bishai, BNL 34 p.34/36 Conclusions: 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 1290 or 2540 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. Constraints on 3-generation model and further improvements in δ cp measurement can then be achieved with ν running.

35 BACKUP SLIDES Mary Bishai, BNL 35 p.35/36

36 Mary Bishai, BNL 36 p.36/36 Running with RHIC The AGS is also the Au/proton injector for the Relativistic Heavy Ion Collider. If ν-beamline comes into operation in 2012 will share beam time with RHIC and RSVP RSVP and ν-superbeam can share 85% time during RHIC heavy ion run.

BNL Very Long Baseline Neutrino Oscillation Expt.

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. Mary Bishai,