STATUS OF BNL SUPER NEUTRINO
BEAM PRORAM

W. T. Weng
Brookhaven National Laboratory

NBI2003, KEK
November 7-11, 2003

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 ProgramConclusion

Physics Goals of theVery Long Baseline Neutrino Program
We introduce a plan to provide the following goals in a single facility:• precise determination of the oscillation parameters ∆m322 and sin22θ23• detection of the oscillation of νµ → νe and measurement of sin22θ13• measurement of ∆m212 sin22θ12 in a νµ → νe appearance mode,independent of the value of θ13• verification of matter enhancement and the sign of ∆m322• determination of the CP-violation parameter δCP 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 programof neutrino measurements. If the value of sin22θ13 happens to be larger than~0.01, then all the parameters, including CP-violation can be determined inthe VLB program presented here.

Advantages of a Very Long Baselineνµ DISAPPEARANCE
BNL-HS 2540 km

2502sin 2θ23 = 1.0∆m 32 = 2.5e-3 eV
2200

21 MW, 0.5 MT, 5e7 sec
No oscillations: 13290 evts

150

With oscillations: 6538 evts
Background: 1211 evts

100

50

00

123

• neutrino oscillations result fromthe factor sin2(∆m322 L / 4E)
modulating the ν flux for eachflavor (here νµ disappearance)• the oscillation period is directly
proportional to distance andinversely proportional to energy• with a very long baseline actualoscillations are seen in thedata as a function of energy• the multiple-node structure of thevery long baseline allows the∆m322 to be precisely measured
by a wavelength rather than anamplitude (reducing systematic
45678910errors)
Reconstructed ν Energy (GeV)

Baseline Length and Neutrino Energy• for a fixed phase angle, e.g. π/2,
the ratio of distance to energy isfixed (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 νinteractions background• these conditions prescribe aneeded baseline of greater than2000 km from source to detector• by serendipity, the distance from
BNL to the Homestake Minein Lead, SD is 2540 km

Mass -ordering and CP-violation Parameter δCP• the CP-violation parameter δCP canbe measured in the VLB exp. Andis relatively insensitive to the valueof sin22θ13• the mass-ordering of the neutrinos
is determined in the VLB exp;
ν1 < ν2 < ν3 is the natural orderbut ν1 < ν3 < ν2 is still possible
experimentally; VLB determines
this, using the effects of matter on
the higher-energy neutrinos

AGS Intensity History

1 MW AGS

Total Accelerated Protons at the AGS
accelerated protons ( red = SEB , blue = FEB )1.0 ×1.0E+201020
0.8 ×8.0E+191020
0.6 ×6.0E+191020
0.4 ×4.0E+191020
0.2 ×2.0E+191020
0Jan-02

Jan-01

Jan-00Jan-99Jan-98Jan-97

Jan-96

Jan-95Jan-94

0.0E+00

Jan-93

Total accelerated protons

1.2 ×1.2E+201020

Slow extracted beam (Kaon decay)
Fast extracted beam (g-2)
Note: Lower total accelerated protons in later years
due to much shorter running time

AGS Upgrade to 1 MWTo RHIC
To Target Station

High Intensity Sourceplus RFQ
200 MeV Drift Tube Linac
BOOSTERAGS

1.2 GeV → 28 GeV
0.4 s cycle time (2.5 Hz)

200 MeV
400 MeVSuperconducting Linacs

800 MeV
1.2 GeV
0.2 szz

0.2 s

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 gradientfurther upgrade to 5 Hz possible (x 2)

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

Value
1 MW
0.4×1013
28 GeV230
38 mA
2.5 Hz
400 ms0.72 ms
9.6 ×1013
0.75
2420/30 mA

Superconducting Linac Parameters
Linac Section

LEMEHE

Av Beam Pwr, kW
7.14
Av Beam Curr, mA
35.7
K.E. Gain, MeV
200Frequency, MHz805
Total Length, m
37.82
Accel Grad, MeV/m 10.8norm rms ε, π mm-mr 2.0

14.0
35.7
4001610
41.40
23.5
2.0

14.0
35.7
4001610
38.32
23.4
2.0

Neutrino Beam Production• 1 MW He gas-cooled Carboncarbon target• New horn design• Target on down-hill slope forlong baseline experiment• Beam dump well above groundwater table to avoid activation

Neutrino Spectrum at 1 km

Low Z (Carbon) target seems
feasible for 1 MW, 28 GeV
proton beam.
Thin low Z target minimizes
reabsorption which increases
flux of high energy neutrinos

Upgrade to 4MW

1.

Raise SCL energy to 1.5 GeV, AGS repetition rate to 5Hz
with 2 x 1014ppp.

2.

Add post AGS accelerator to 40 GeV, raise AGS rep rate to5 Hz with 1.4 x 1014ppp.

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 Groupfor 2MW neutrino superbeam

3. April/02

Presentation of HIHB Hadron Beam Workshop
at FNAL

4. June/02

Presentation of NuFact 2002 Workshop, London

5. Oct/02

BNL NWG Report-I

6. Feb/03

HEPAP Facility Subcommittee presentation

Chronology of BNL Super Neutrino Beam Program (cont’d.)7. April/03

BNL NWG Report-II

8. Aug/03

Phys. Rev. D68, 012002 (2003)

9. Nov/03

NBI2003, KEK

10. Dec/03

UCLA Workshop on Detector

11. April/04

BNL Workshop on Source

Conclusions
1. The VLBL approach is capable of resolving most of theneutrino physics issues, including that of cp violation.
2. The feasibility has been demonstrated for a 1MW
upgrade for the AGS
3. 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 theneutrino factory.