Very Long Baseline experiment with a Super Neutrino Beam Brookhaven National Laboratory

1. Very Long Baseline experiment with a Super Neutrino Beam Brookhaven National Laboratory (work of the neutrino working group) Presented to the DPF 2003, Philadelphia (Ref: hep-ph/0303081) Milind V. Diwan (Stephen Kahn) Brookhaven National Laboratory Philadelphia, PA April 7, 2003 M. Diwan

2. Physics Importance of Neutrino Oscillations Complete measurement of the neutrino oscillation parameters is a physics goal of fundamental importance: neutrinos are fundamental particles whose full description in terms of mass and mixing parameters is basic to the progress of particle physics the mass scales among the neutrinos may help us understand the evolution of all particle masses down from the Planck scale if CP-violation is observed in the neutrino system, it will be quite large and may drive the much smaller CP-violation in the quark sector the early universe implications of large CP-violation in the neutrino sector might help explain the mass asymmetry in the present universe M. Diwan

3. Physics Goals of the Very Long Baseline Neutrino Program We introduce a plan to provide the following goals in a single facility: precise determination of the oscillation parameters Dm322 and sin22q23 detection of the oscillation ofnmneand measurement of sin22q13 measurement of Dm212sin22q12 in anmneappearance mode, can be made if the value of q13 is zero verification of matter enhancement and the sign of Dm322 determination of the CP-violation parameter dCP in the neutrino sector The use of a single neutrino super beam source and half-megaton neutrino detector will optimize the efficiency and cost-effectiveness of a full program of neutrino measurements. If the value of sin22q13 happens to be larger than ~0.01, then all the parameters, including CP-violation can be determined in the VLB program presented here. M. Diwan

4. BNL  Homestake Super Neutrino Beam Homestake BNL 2540 km 28 GeV protons, 1 MW beam power 500 kT Water Cherenkov detector 5e7 sec of running, Conventional Horn based beam M. Diwan

5. Neutrino spectrum from AGS • Proton energy 28 GeV • 1 MW total power • ~1014 proton per pulse • Cycle 2.5 Hz • Pulse width 2.5 mu-s • Horn focused beam with graphite target • 5x10-5 n/m2/POT @ 1km M. Diwan

6. Advantages of a Very Long Baseline  neutrino oscillations result from the factor sin2(Dm322L / 4E) modulating the n flux for each flavor (here nm disappearance)  the oscillation period is directly proportional to distance and inversely proportional to energy  with a very long baseline actual oscillations are seen in the data as a function of energy  the multiple-node structure of the very long baseline allows the Dm322 to be precisely measured by a wavelength rather than an amplitude (reducing systematic errors) M. Diwan

7. Baseline Length and Neutrino Energy  for a fixed phase angle, e.g. p/2, the ratio of distance to energy is fixed (see sloped lines in Figure)  the useful neutrino energy range in a beam derived from a proton production source is restricted: below ~1 GeV by Fermi mom. in the target nucleus above ~8 GeV by inelastic n interactions background  these conditions prescribe a needed baseline of greater than 2000 km from source to detector  by serendipity, the distance from BNL to the Homestake Mine in Lead, SD is 2540 km M. Diwan

8. Prob(nm to ne) through earth • Above 3 GeV matter enhancement by about factor of 2. • 1-3 GeV : small matter effect, large CP effect. • <1.5 GeV: Dm221 contribution increases at low energy. • Very long baseline separates physics effects. M. Diwan

9. VLB Application to Measurement of Dm322  the multiple node method of the VLB measurement is illustrated by comparing the BNL 5-year measurement precision with the present Kamiokande results and the projected MINOS 3-year measurement precision; all projected data include both statistical and systematic errors  there is no other plan, worldwide, to employ the VLB method (a combination of target power and geographical circumstances limit other potential competitors)  other planned experiments can’t achieve the VLB precision M. Diwan

10. ne Appearance Measurements  a direct measurement of the appearance of nmneis important; the VLB method competes well with any proposed super beam concept  for values > 0.01, a measurement of sin22q13 can be made (the current experimental limit is 0.12)  for most of the possible range of sin22q13, a good measurement of q13and the CP-violation parameter dCP can be made by the VLB experimental method M. Diwan

11. ne Appearance Measurements (Cont.) even if sin22q13 = 0, the current best-fit value of Dm212 = 7.3x10-5 induces a ne appearance signal  the size of the ne appearance signal above background depends on the value of Dm212; the figure left indicates the range of possible measured values for the ne yields above background for various assumptions of the final value of Dm212 M. Diwan

12. Mass -ordering and CP-violation Parameter dCP  the CP-violation parameter dCP can be measured in the VLB exp. And is relatively insensitive to the value of sin22q13  the mass-ordering of the neutrinos is determined in the VLB exp; n1 < n2 < n3 is the natural order but n1 < n3 < n2 is still possible experimentally; VLB determines this, using the effects of matter on the higher-energy neutrinos M. Diwan

13. Possible limits on sin22q13 versus dCP • For normal mass ordering • limit on sin22q13 will be 0.005 • for no CP • Any experiment with horn • focused beam is unlikely to • do better. • If reversed mass ordering • then need to run • antineutrinos M. Diwan

14. Important Observations • If signal is well above background CP resolution is indep. ofsin22q13 • Wide band beam and 2540 km eliminate many parameter correlations. • For 3-generation mixing only neutrino running is needed. M. Diwan

15. Resolution on CP phase • Resolution gets better rapidly as Dm212 becomes larger. • Resolution of 20 deg as long as signal sufficiently above background. M. Diwan

16. AGS Target Power Upgrade to 1 MW  the AGS Upgrade to provide a source for the 1.0 MW Super Neutrino Beam will cost $265M FY03 (TEC) dollars M. Diwan

17. AGS 1 MW Upgrade and SC Linac Parameters Superconducting Linac Parameters Linac Section LE ME HE Av Beam Pwr, kW 7.14 14.0 14.0 Av Beam Curr, mA 35.7 35.7 35.7 K.E. Gain, MeV 200 400 400 Frequency, MHz 805 1610 1610 Total Length, m 37.82 41.40 38.32 Accel Grad, MeV/m 10.8 23.5 23.4 norm rms e, p mm-mr 2.0 2.0 2.0 Proton Driver Parameters Item Value Total beam power 1 MW Protons per bunch 0.41013 Beam energy 28 GeV Injection turns 230 Average beam current 38 mA Repetition rate 2.5 Hz Cycle time 400 ms Pulse length 0.72 ms Number of protons per fill 9.61013 Chopping rate 0.75 Number of bunches per fill 24 Linac average/peak current 20/30 mA M. Diwan

18. 1 MW Target for AGS Super Neutrino Beam  1.0 MW He gas-cooled, Carbon-Carbon target for the Super Neutrino Beam M. Diwan

19. Super Neutrino Beam Geographical Layout  BNL can provide a 1 MW capable Super Neutrino Beam for $104M FY03 (TEC) dollars  the neutrino beam can aim at any site in the western U.S.; the Homestake Mine is shown here  there will be no environmental issues if the beam is produced atop the hill illustrated here and the beam dumped well above the local water table  construction of the Super Neutrino Beam is essentially de-coupled from AGS and RHIC operations M. Diwan

20. 3-D Neutrino Super Beam Perspective M. Diwan

21. Conclusions measurement of the complete set of neutrino mass and mixing parameters is very compelling for the advance of particle physics the Very Long Baseline method, utilizing a 1 MW Super Neutrino Beam from BNL’s AGS, coupled with a half-megaton water Cerenkov detector in the Homestake Mine in Lead, SD, offers a uniquely effective plan the half-megaton detector was not detailed in this presentation but we note that the UNO detector has all the properties needed for the VLB neutrino program and offers important and compelling physics beyond the neutrino oscillations work. neutrino only running, low sensitivity to systematics, high sensitivity to mass ordering, broad spectrum of physics. This plan receivedhigh marks from HEPAP facilities committee in February. M. Diwan

22. Questions From the Subcommittee What size collaboration is needed to construct the accelerator and to construct and do physics with the detector? The accelerator upgrades and most of the technical design and construction work for the BNL site work would be accomplished by the staff of the C-A Department; the equivalent questions for the detector are left to Prof. Jung; we have estimated 15% EDIA, or $33 M over 5 years, amounting to an average design/construction professional staff of 66 FTE (physicists are not counted in the EDIA budget). The detector collaboration is expected to number between 300 and 500 physicists (estimated by Prof. Jung). What is the timeline/schedule for the accelerator and beamline? The technically (not budget) limitedschedule would comprise a 3-year R&D period (FY04-06) followed by a 5-year construction period (FY07-FY11); the critical path would definitely be the R&D to develop the superconducting RF cavities and RF power system. All the other systems would require less R&D time. There are no novel or unproven technologies in the accelerator and neutrino beam concept. M. Diwan

23. Questions From the Subcommittee (Cont.) What is the estimated total project cost (including the proton driver, beamline, and detector = UNO)? Please give the basis of the cost estimate. AGS Upgrade & SC Linac $156.8M (C-AD staff, recent SNS and BNL experience) Neutrino Beam Cost 61.7M (C-AD/Phys. Dept. staff, recent BNL experience) EDIA, Conting., Proj. G&A 150.0M (BNL project experience and current rates) Total Estimated Cost (TEC) $368.5M (fully burdened) 3 yrs R&D ($1M, 3M, 5M) 9.0M (estimated accelerator R&D in FY04, 05, 06) Pre-ops, starting in FY09 12.0M (this would accomplish the needed pre-ops) Total Project Cost (TPC) $389.5M (fully burdened) These estimates are provided in FY 2003 dollars and are for the Accelerator and Super Neutrino Beam elements only. Prof. Jung will provide the cost estimate for the UNO Detector which we use as the basis for our physics calculations. The basis of estimate comprises current costs that C-AD and BNL engineers and physicists derive from recent and ongoing BNL projects. The level of EDIA is scaled from recent BNL projects in HENP areas of DOE. M. Diwan