STATUS OF BNL SUPER NEUTRINO BEAM PRORAM

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STATUS OF BNL SUPER NEUTRINOBEAM PRORAM
W. T. Weng Brookhaven National Laboratory NBI2003
, KEK November 7-11, 2003
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OUTLINE

• Physics Reach from a Very Long Baseline Neutrino
  Beam
• AGS High Intensity Performance
• AGS Upgrade (1MW)
• AGS Upgrade (4MW)
• Chronology of BNL Super Neutrino Beam Program
• Conclusion

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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 of
nm ? ne and measurement of sin22q13 ?
measurement of Dm212 sin22q12 in a nm ? ne
appearance mode, independent of the value of
q13 ? 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.

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Advantages of a Very Long Baseline
? neutrino oscillations result from the factor
sin2(Dm322 L / 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)
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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
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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 lt n2 lt n3 is the natural
order but n1 lt n3 lt n2 is still possible
experimentally VLB determines this, using the
effects of matter on the higher-energy
neutrinos
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AGS Intensity History
1 MW AGS
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Total Accelerated Protons at the AGS
Slow extracted beam (Kaon decay) Fast
extracted beam (g-2) Note Lower total
accelerated protons in later years due
to much shorter running time
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AGS Upgrade to 1 MW

• 1.2 GeV superconducting linac extension for
  direct injection of 1 ? 1014 protons low beam
  loss at injection high repetition rate
  possible further upgrade to 1.5 GeV and 2 ? 1014
  protons per pulse possible (x 2)
• 2.5 Hz AGS repetition rate triple existing
  main magnet power supply and magnet current
  feeds double rf power and accelerating
  gradient further upgrade to 5 Hz possible (x 2)

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AGS 1 MW Upgrade and SC Linac Parameters
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
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 Frequ
ency, 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
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Neutrino Beam Production

• 1 MW He gas-cooled Carbon-carbon target
• New horn design
• Target on down-hill slope forlong baseline
  experiment
• Beam dump well above ground water table to avoid
  activation

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Neutrino Spectrum at 1 km
Low Z (Carbon) target seemsfeasible for 1 MW, 28
GeV proton beam. Thin low Z target
minimizesreabsorption which increases flux of
high energy neutrinos
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Upgrade to 4MW

• Raise SCL energy to 1.5 GeV, AGS repetition rate
  to 5Hz with 2 x 1014ppp.
• Add post AGS accelerator to 40 GeV, raise AGS rep
  rate to 5 Hz with 1.4 x 1014ppp.

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Chronology of BNL Super Neutrino Beam Program

• 1. June/01 US Feasibility Study-II of a
  Neutrino Factory
• 2. Dec/01 Establishment of BNL Neutrino
  Working Group
• for 2MW neutrino
  superbeam
• April/02 Presentation of HIHB Hadron Beam
  Workshop
• at FNAL
• June/02 Presentation of NuFact 2002
  Workshop, London
• Oct/02 BNL NWG Report-I
• Feb/03 HEPAP Facility Subcommittee
  presentation

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Chronology of BNL Super Neutrino Beam Program
(contd.)

• April/03 BNL NWG Report-II
• Aug/03 Phys. Rev. D68, 012002 (2003)
• Nov/03 NBI2003, KEK
• Dec/03 UCLA Workshop on Detector
• April/04 BNL Workshop on Source

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Conclusions

• The VLBL approach is capable of resolving most of
  the neutrino physics issues, including that of cp
  violation.
• The feasibility has been demonstrated for a 1MW
  upgrade for the AGS
• It is possible to further upgrade the AGS to 4MW
• Such a high power proton driver is
  essential for very long base line neutrino
  experiment and also for the neutrino factory.