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Very Long Baseline experiment with a 1 MW Neutrino Beam Brookhaven National Laboratory

Very Long Baseline experiment with a 1 MW Neutrino Beam Brookhaven National Laboratory (work of the BNL neutrino working group Upenn, Utexas, StonyBrook, Princeton) Presented to the BSA Review committee (Ref: Diwan et al., PRD68, 012002, 2003) Milind V. Diwan

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Very Long Baseline experiment with a 1 MW Neutrino Beam Brookhaven National Laboratory

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  1. Very Long Baseline experiment with a 1 MW Neutrino Beam Brookhaven National Laboratory (work of the BNL neutrino working group Upenn, Utexas, StonyBrook, Princeton) Presented to the BSA Review committee (Ref: Diwan et al., PRD68, 012002, 2003) Milind V. Diwan Brookhaven National Laboratory New York, NY July 22, 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 Neutrinos may have a unique role in particle physics: They allow direct measurement of the fundamental. Their mass scales and other properties are so different that perhaps they allow us to understand Plank scale physics. If neutrinos are observed to violate CP in a big way then they may be driving the much smaller CP-violation in the quark sector and the Baryon Asymmetry of the Universe. M. Diwan

  3. Current neutrino picture • Large mixings except for Ue3. • No information on Ue3 • No knowledge of phases in the mixing. M. Diwan

  4. Mass differences • Absolute scale of neutrino mass known to be less than 2 – 3 eV. • Known from atmospheric neutrino data: Dm231=m23-m21~ (+/-)0.0025 eV2 • Known from solar neutrinos and reactors: Dm221=m22-m21~ 0.000073 eV2 • Both with large errors and no knowledge of sign of Dm231 M. Diwan

  5. Physics Goals of the BNL 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 intense 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 BVLB program presented here. BNL-Very-Long-BaseLine (BVLB) M. Diwan

  6. Competing ideas • Use narrow band beam to observe nmne • Make neutrino factory to observe nenm • Both approaches focus on lowering background using a better beam. • Disadvantage: neither will see oscillatory pattern in energy spectrum. Will most likely need another step to achieve sufficient physics breadth. • For the next stage of CP violation both must run with antineutrinos and also build detectors at multiple baselines. M. Diwan

  7. BNL  Homestake 1 MW 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

  8. 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 • 52000 CC events. • 17000 NC events. M. Diwan

  9. 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

  10. VLB Application to Measurement of Dm322  the multiple node method of the BVLB 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 BVLB method (a combination of target power and geographical circumstances limit other potential competitors)  other planned experiments can’t achieve the BVLB precision M. Diwan

  11. 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 BVLB experimental method 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. Comparisons to other projects • BNL-HS has reach to lower Dm2 and a larger physics agenda. • No conventional beam experiments can beat the background from beam contamination • Plot ignores CP, multi-node, matter effects 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. 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

  16. 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

  17. 1 MW Target for AGS Super Neutrino Beam  1.0 MW He gas-cooled, Carbon-Carbon target for the Super Neutrino Beam M. Diwan

  18. 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

  19. 3-D Neutrino Super Beam Perspective M. Diwan

  20. Detector • Requirements: • 500 kTons fiducial mass • ~10 % energy resolution on quasielastic events • Muon/electron discrimination at <1% • 1, 2, 3 track event separation • Showering NC event rejection at factor of ~15 M. Diwan

  21. NC events have a shape that falls in Q2 and visible energy regardless of neutrino energy. A 1-4 GeV neutrino beam and 2500 km ideal because background is naturally low at 3 GeV peak. M. Diwan

  22. Liquid Argon TPC 100 kT module never been built. Too large a step from current 300ton. Needs detailed simulations to make sure there are no hidden pitfalls, but should perform adequately. Water Cherenkov 50 kT SuperK is existence proof. Current understanding of background rejection: need another factor of 3 to 5 in the 1-2 GeV range. Could additional imaging capability help? (Aquarich concept by Ypsilantis) Detector choices M. Diwan

  23. 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 • Work continues to understand the best detector design. • Detector has applications far beyond neutrino oscillations. • A deep underground 500 kT detector with the described performance • characteristics will be a unique facility for Physics. M. Diwan

  24. Big Issues • Do nothing but wait for JHF-SK ? • Only do a sin22q13 experiment. Doesn’t matter how long it takes ? >10 yrs. • Perform a quick reactor based sin22q13 experiment. Say 5 years ? • Keep working on neutrino factory. Ignore all else. • What is the best thing for particle physics from programmatic and funding point of view ? M. Diwan

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