Very Long Baseline experiment with a Super Neutrino

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

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 April 7, 2003 M. Diwan

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 Dm 322 and sin 22 q 23 detection of the oscillation of nm ne and measurement of sin 22 q 13 measurement of Dm 212 sin 22 q 12 in a nm ne appearance mode, can be made if the value of q 13 is zero verification of matter enhancement and the sign of Dm 322 determination of the CP-violation parameter d. CP 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 sin 22 q 13 happens to be larger than ~0. 01, then all the parameters, including CP-violation can be determined in the VLB program presented here. April 7, 2003 M. Diwan

BNL Homestake Super Neutrino Beam Homestake BNL 2540 km 28 Ge. V protons, 1 MW beam power 500 k. T Water Cherenkov detector 5 e 7 sec of running, Conventional Horn based beam April 7, 2003 M. Diwan

Neutrino spectrum from AGS • • • Proton energy 28 Ge. V 1 MW total power ~10 14 proton per pulse Cycle 2. 5 Hz Pulse width 2. 5 mu-s Horn focused beam with graphite target • 5 x 10 -5 n/m 2/POT @ 1 km April 7, 2003 M. Diwan

Advantages of a Very Long Baseline neutrino oscillations result from the factor sin 2(Dm 322 L / 4 E) 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 Dm 322 to be precisely measured by a wavelength rather than an amplitude (reducing systematic errors) April 7, 2003 M. Diwan

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 Ge. V by Fermi mom. in the target nucleus above ~8 Ge. V 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 April 7, 2003 M. Diwan

Prob(nm to ne) through earth • Above 3 Ge. V matter enhancement by about factor of 2. • 1 -3 Ge. V : small matter effect, large CP effect. • <1. 5 Ge. V: Dm 221 contribution increases at low energy. • Very long baseline separates physics effects. April 7, 2003 M. Diwan

VLB Application to Measurement of Dm 322 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 April 7, 2003 M. Diwan

ne Appearance Measurements a direct measurement of the appearance of nm ne is important; the VLB method competes well with any proposed super beam concept for values > 0. 01, a measurement of sin 22 q 13 can be made (the current experimental limit is 0. 12) for most of the possible range of sin 22 q 13, a good measurement of q 13 and the CP-violation parameter d. CP can be made by the VLB experimental method April 7, 2003 M. Diwan

ne Appearance Measurements (Cont. ) even if sin 22 q 13 = 0, the current best-fit value of Dm 212 = 7. 3 x 10 -5 induces a ne appearance signal the size of the ne appearance signal above background depends on the value of Dm 212; the figure left indicates the range of possible measured values for the ne yields above background for various assumptions of the final value of Dm 212 April 7, 2003 M. Diwan

Mass -ordering and CP-violation Parameter d. CP the CP-violation parameter d. CP can be measured in the VLB exp. And is relatively insensitive to the value of sin 22 q 13 the mass-ordering of the neutrinos is determined in the VLB exp; n 1 < n 2 < n 3 is the natural order but n 1 < n 3 < n 2 is still possible experimentally; VLB determines this, using the effects of matter on the higher-energy neutrinos April 7, 2003 M. Diwan

Possible limits on sin 22 q 13 versus d. CP • For normal mass ordering limit on sin 22 q 13 will be 0. 005 for no CP Any experiment with horn focused beam is unlikely to do better. • April 7, 2003 M. Diwan If reversed mass ordering then need to run antineutrinos

Important Observations • If signal is well above background CP resolution is indep. of sin 22 q 13 • Wide band beam and 2540 km eliminate many parameter correlations. • For 3 -generation mixing only neutrino running is needed. April 7, 2003 M. Diwan

Resolution on CP phase • Resolution gets better rapidly as Dm 212 becomes larger. • Resolution of 20 deg as long as signal sufficiently above background. April 7, 2003 M. Diwan

AGS Target Power Upgrade to 1 MW the AGS Upgrade to provide a source for the 1. 0 MW Super Neutrino Beam will cost $265 M FY 03 (TEC) dollars April 7, 2003 M. Diwan

AGS 1 MW Upgrade and SC Linac Parameters Proton Driver Parameters Item Total beam power Protons per bunch Beam energy Injection turns Average beam current Repetition rate Cycle time Pulse length Number of protons per fill Chopping rate Number of bunches per fill Linac average/peak current April 7, 2003 Value 1 MW 0. 4 1013 28 Ge. V 230 38 m. A 2. 5 Hz 400 ms 0. 72 ms 9. 6 1013 0. 75 24 20/30 m. A Superconducting Linac Parameters Linac Section Av Beam Pwr, k. W Av Beam Curr, m. A K. E. Gain, Me. V Frequency, MHz Total Length, m Accel Grad, Me. V/m norm rms e, p mm-mr M. Diwan LE ME HE 7. 14 35. 7 200 805 37. 82 10. 8 2. 0 14. 0 35. 7 400 1610 41. 40 23. 5 2. 0 14. 0 35. 7 400 1610 38. 32 23. 4 2. 0

1 MW Target for AGS Super Neutrino Beam 1. 0 MW He gas-cooled, Carbon-Carbon target for the Super Neutrino Beam April 7, 2003 M. Diwan

Super Neutrino Beam Geographical Layout BNL can provide a 1 MW capable Super Neutrino Beam for $104 M FY 03 (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 April 7, 2003 M. Diwan

3 -D Neutrino Super Beam Perspective April 7, 2003 M. Diwan

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 received high marks from HEPAP facilities committee in February. April 7, 2003 M. Diwan

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) limited schedule would comprise a 3 -year R&D period (FY 04 -06) followed by a 5 -year construction period (FY 07 -FY 11); 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. April 7, 2003 M. Diwan

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 Neutrino Beam Cost EDIA, Conting. , Proj. G&A $156. 8 M (C-AD staff, recent SNS and BNL experience) 61. 7 M (C-AD/Phys. Dept. staff, recent BNL experience) 150. 0 M (BNL project experience and current rates) Total Estimated Cost (TEC) $368. 5 M (fully burdened) 3 yrs R&D ($1 M, 3 M, 5 M) Pre-ops, starting in FY 09 Total Project Cost (TPC) 9. 0 M (estimated accelerator R&D in FY 04, 05, 06) 12. 0 M (this would accomplish the needed pre-ops) $389. 5 M (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. April 7, 2003 M. Diwan