STATUS OF BNL SUPER NEUTRINOBEAM 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 sin2223

detection of the oscillation of e and measurement of sin2213

measurement of m212 sin2212 in a e appearance mode,

independent of the value of 13

verification of matter enhancement and the sign of m322

determination of the CP-violation parameter 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 sin2213 happens to be larger than

~0.01, then all the parameters, including CP-violation can be determined in

the VLB program presented here.

Advantages of a Very Long Baseline

DISAPPEARANCE

0

50

100

150

200

250

0 1 2 3 4 5 6 7 8 9 10

Reconstructed Energy (GeV)

BNL-HS 2540 km

sin2223 = 1.0

m2 32 = 2.5e-3 eV2

1 MW, 0.5 MT, 5e7 sec

No oscillations: 13290 evts

With oscillations: 6538 evts

Background: 1211 evts

neutrino oscillations result from

the factor sin2(m322 L / 4E)

modulating the flux for each

flavor (here 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

m322 to be precisely measured

by a wavelength rather than an amplitude (reducing systematic errors)

Baseline Length and Neutrino Energy

for a fixed phase angle, e.g. /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 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

Mass -ordering and CP-violation Parameter CP

the CP-violation parameter CP can

be measured in the VLB exp. And is relatively insensitive to the value

of sin2213

the mass-ordering of the neutrinos is determined in the VLB exp;

1 < 2 < 3 is the natural order

but 1 < 3 < 2 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 AGSAGS Accelerated Protons 1/1/1993 to 9/30/2002

0.0E+00

2.0E+19

4.0E+19

6.0E+19

8.0E+19

1.0E+20

1.2E+20

Jan

-93

Jan

-94

Jan

-95

Jan

-96

Jan

-97

Jan

-98

Jan

-99

Jan

-00

Jan

-01

Jan

-02

date

acce

lera

ted

pro

ton

s (

red

= S

EB

, b

lue

= F

EB

)

0.8 1020

0.6 1020

0.4 1020

0.2 1020

0

Tot

al a

ccel

erat

ed p

roto

ns 1.0 1020

1.2 1020

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 MW

200 MeV Drift Tube Linac

BOOSTER

High Intensity Sourceplus RFQ

Superconducting Linacs

To RHIC

400 MeV

800 MeV

1.2 GeV

To Target Station

AGS1.2 GeV 28 GeV

0.4 s cycle time (2.5 Hz)

0.2 s 0.2 s

200 MeV

1.2 GeV superconducting linac extension for direct injection of ~ 1 1014 protonslow beam loss at injection; high repetition rate possiblefurther upgrade to 1.5 GeV and 2 1014 protons per pulse possible (x 2)

2.5 Hz AGS repetition ratetriple existing main magnet power supply and magnet current feedsdouble rf power and accelerating gradientfurther upgrade to 5 Hz possible (x 2)

AGS 1 MW Upgrade and SC Linac Parameters

Proton Driver Parameters

Item Value

Total beam power 1 MWProtons per bunch 0.41013

Beam energy 28 GeVInjection turns 230Average beam current 38 mARepetition rate 2.5 HzCycle time 400 msPulse length 0.72 msNumber of protons per fill 9.6 1013

Chopping rate 0.75Number of bunches per fill 24Linac average/peak current 20/30 mA

Superconducting Linac Parameters

Linac Section LE ME HE

Av Beam Pwr, kW 7.14 14.0 14.0Av Beam Curr, mA 35.7 35.7 35.7K.E. Gain, MeV 200 400 400Frequency, MHz 805 1610 1610Total Length, m 37.82 41.40 38.32Accel Grad, MeV/m 10.8 23.5 23.4norm rms , mm-mr 2.0 2.0 2.0

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

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

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 to 5 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 Group

for 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 the neutrino 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 the neutrino factory.