Overview of the KEK Neutrino
Beam Facility and its Operation
Summary after September 2000 (NBI2000 @ FNAL)
K.H. Tanaka
for the KEK-PS
Beam Channel Group &K2K Beam Monitor Group.
March 14th 2002
@NBI2002,CERN.

••••

Contents
Introduction
Performance
Summary
Strategy or Future
Run PlanK2K Experiment

The First Long Baseline (250km)
Neutrino Oscillation Experiment

Far Detector: SK
50kt Water C Detector••••

Shooting SideKEK 12GeV PSνBeam Line
νBeam Facility
Front DetectorKEK Neutrino Beam Facility

Bird’s Eye View of KEKKEK Neutrino Beam Facility ITop View

Neutrino Beam Facility IISide View

Schematic Drawing of the FacilityPrimary Proton Beam Line (Extended Part)↑Slope(Straight) Section
ARC Section (No Crane)↓↑Slope (Straight) Section,
5m/72m. 20t Crane is here.

Primary Proton Beam Line (N-Hall)• Small Beam line room, however top can be opened!
• Service tunnel is prepared at downstairs• Quick disconnect devices of Water&Electricity weredeveloped.

For the Safety
Construction & Maintenance
Highly Radioactive!
↓• Often our high-class people says that we should learn
Egyptian Technology to save MONEY.
• This may be wrong. We need wider space & Crane tohandle highly radioactive beam line elements!

Primary Proton Monitors• Profile– Luminescence Screen (蛍光板)– SPIC• Intensity– CT– SECThe Latest Upgrades• Vacuum system improvement– Many vacua → Single vacuum section– Most Monitors were put into vacuum.

• Magnets were replaced to larger acceptance ones.
Beam Transmission: 5% up→

Horns, Target & Decay Volume• Two Horns(Collector &Reflector).
• Built-in Target inCollector• 250kA Operation• 10M Excitation with30mmφTarget• Transformer near-by• 200m Decay Volume
filled with He.

Cross Sectionof Collector

Power Supplyfor HornsNeutrino Intensity Enhancement byHorns

Neutrino Energy

Decay Volume & Muon Monitor

Muon/Proton Beam profiles
Proton Profile
measured bySPIC. ↓↑Muon Profile measured by
Muon Chamber and SSD’s.

Neutrino Energy (Monte Carlo)

012Eν(GeV)

KEKSK(300m)(250km)340123Eν(GeV)

4

Neutrino Profile (Monte Carlo)

KEKSciFiSKSKMu/Fe10mrad

0210mrad46R(m)

810 12012R(km)3

Positioning Precision from KEK to SK
Experimental Requirement:±1mrad (Long Term)• Positioning by GPS and Optical Survey⊿Horizontal=1.2m, ⊿Vertical=0.7m,〜±0.005mr,• Beam Line Alignment and Monitoring
Horizaintal〜±0.02mr,
Vertical 〜±0.05mr,• Beam Control and Tuning (Short Term)
Horizaintal〜±0.03mr,
Vertical 〜±0.06mr,

Performance
June 1999 - July 2001
Or, Long Range Beam Stability!?

Delivered Protons on Target (POT)

4.8x1019 POT
for Analysis

Date

Goal:1020 POT (forAnalysis?)Muon Profile: Centoroid Stability
Horizonral← +1 mrad← -1 mrad

Vertical← +1 mrad← -1 mradBeam Shift Correlation
Xptarget = Center

Xptarget = 3mm OFFMuon/ProtonCorrelation• Horn is –100 times ImageMagnifier.
• For accurate aiming, stable
positioning of proton beamon target is essential.
• Beam monitors of primary
protons are very important.

Front Detector Configuration
Muon RangeDetector

1ktWCD: Same Type Detector as SK
MRD and SciFi: Fine Grained Precise ν Detector
MRD: Massive and Large Solid Angle ν Detector

Front Detector
Photograph←1kt Baby Kamioka←SciFi←Lead Glass←Muon RangeDetector

Front Detector as Neutrino Beam Monitor

Neutrino Beam Profile (MRD)• One MonthData• Yellow belt:
Fitting Error• Dot-dashed line:
Center fromGPS survey

Neutrino Profile: Centroid Stability(Muon Range Detector)
Horizontal←+1 mrad← -1 mrad

Vertical←+1 mrad← -1 mradNeutrino Event Rate Stability(Muon Range Detector/POT)
Horn 250kA← Target 30 mmφ← Horn 200kA
Target 20 mmφ

Event Number at SK/POT

こるもごろふすみるのふ検定

SK Event: Time Resolution-0.2μsec≦⊿T=Tsk-Tkek-TOF ≦1.3μsec

Observed SK events
4.8x1019pot (Jun99-Jul01)

Cf. MRD:+12.7

87.4 -13.9+11.9

SciFi : 87.3 -11.9

No oscillation hypothesis is disfavoured at 97％ CL.

Summary or Present Status• Accelerator, Beam channel, Horns, and BeamMonitors are all stable and ~5x1019 POT wasAchieved.
• Excitation number our Magnetic Horns recentlyexceeded ~10 M with 250kA.
• Nice aiming to Super-K continues and we havestable event rate at Super-K.
• Beam side is now OK! We are waiting for therecovery of Super-K.

Strategy of the HORN Operation/Replacement• September(2002)– Replacement of Horns• December (2002)– SK will re-start with areduced PMT density– 6-7 months ContinuousOperation with fast beam
– 6M Excitation– 2.5x1019POT• July (2003)– Cooling Down
– Slow Extraction• November (2003)– Horn Replacement• December (2003)–––6-7 months
Continuous Operation
6M Excitation
2.5x1019POT• August(2004)–Shut Down for JHF
Construction• January(2005)–Magnet Transfer toTokai