Overview of the KEK Neutrino
Beam Facility and its Operation
Summary after December 2002 (Recovery of SK)
K.H. Tanaka
for the KEK-PS Beam Channel Group &K2K Beam Monitor Group.
(Data presented here were prepared & compiled by Dr. Iwashita.)

Contents

1. Introduction
2. Performance
3. Summary
4. Future Run Plan

K2K Experiment

The 2nd Phase of Long Baseline
Neutrino Oscillation Experiment

Far Detector:
SuperKAMIOKANDE 50kt Water Cerenkov Detector••••

Shooting SideKEK 12GeV PSνBeam LineνBeam Facility
Front Detectors

Recovery of SKAccident:
November 12th,2001
Photo by Kamioka Observatory, Institute ofCosmic Ray Research, The University of Tokyo

Recovery History• Reconstruction Completed: December 10th, 2002
• Fast Extraction Tuning Start: December 17th, 2002
• Test Run Start: December 22nd, 2002
• Test Run End: December 25th, 2002
• K2K-II Start: January 18th, 2003
• Now: Running! till February 2004.

AcceleratorComplex
••
•
•
•
•

12GeV-PS
500MeV Booster
40MeV LINAC
Photon Factory
B-FactoryATF

Neutrino Beam Facility

Side View

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

Primary Proton Beam Line (Final Focus Part)

Q-triplet and Correction Magnets → Horns

Horns, Target & Decay Volume• Two Horns(Collector & Reflector).
• Built-in Target inCollector• 250kA Operation• 10M Excitation with
30mmφTarget• Transformer near-by• 200m Decay Volume
filled with He.

Primary Proton Monitors• Profile– Luminescence Screen（蛍光板）– SPIC• Intensity– CT– SEC

Segmented Parallel Plate
Ion Chamber (SPIC) • Operated in He.
• Work in fast Beamwith Time ConstantCircuit.
• 64ch ADC readout(H-32ch, V-32ch)

Decay Volume & Muon Monitor

Muon/Proton Beam profiles
Proton Profile measuredby SPIC. ↓1ch=1.27mm↑Muon Profile measured byMuon Chamber and SSD’s.

Front Detector as Neutrino Beam Monitor

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

Front Detector Configuration
Muon Range
Detector

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

Neutrino Beam Profile (MRD)• One MonthData• Yellow belt:
Fitting Error• Dot-dashedline: Centerfrom GPSsurvey

Super-Kamiokande（Completed in April,１９９６）
50,000 ton water Cherenkov detector (22.5 kton fiducial volume)

４１．４ｍ

Livetime (exposure): 1289 days (79.3 kt・yr)

４０ｍ

Neutrino Energy (Monte Carlo)

012Eν(GeV)KEKSK(300m)(250km)3

40

12
3Eν(GeV)4

Neutrino Profile (Monte Carlo)

KEK
SciFiSKSKMu/Fe10mrad

0210mrad46R(m)

8 10 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
December 2002 November 2003
Or, Long Range Beam Stability!?

Accumulated POT(1018)

First Protons for K2K-II
POT inDecember 2002 =Protons/Pulse(1012)

Restart

21st

22nd

23rd
24th
December 2002

25th

Protons/Pulse(1012)

Accumulated POT(1018)

POT for K2K-II

Date(2003)

7.3x1019 POT
Delivered

5.6x1019 POT
Delivered
4.8x1019 POT
for Analysis

Protons/Pulse(1012)

Accumulated POT(1018)

Delivered Protons on Target (POT)
6.3x1019 POT
for Analysis

Plotteduntil Endof April
Date

Goal:1020 POT (for Analysis)

Muon Profile: Centoroid StabilityHorizonral← +1 mrad← -1 mrad

Vertical← +1 mrad← -1 mradBeam Shift Correction• 1ch shift (day)• 2ch shift (night)↓HumanCorrection•DCCT error?
•Magnet coil?
•Ion source?
•EX septum?

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.

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:TimeResolution-0.2μsec≦⊿T=Tsk-Tkek-TOF ≦1.3μsec

Observed SK events 4.8x1019pot (Jun99-Jul01)

FC 25.5kt
Cf. MRD:+12.7

87.4 -13.9

1626+2.3-2.1

1.5x1019pot (Jan.03-April03)+11.9

SciFi : 87.3 -11.9

No oscillation hypothesis is disfavoured at 97％ CL.

Summary of Present Status• Super-K recovered with half density structure.
• Neutrino shooting immediately re-started!
• Accelerator, Beam channel, Horns, and BeamMonitors are all stable and ~7x1019 POT has
been achieved before 2003 Summer Shutdown• Nice aiming to Super-K continues and we havestable event rate at Super-K.
• Present Beam time started September 30th 2003
continues until February 15th 2004.
• 1020POT will be reached in 2004.

KEK-PS Beam Channel Group

7 Physicists + 6 Engineers + 1 newcomer (Dr. A. Toyoda)
conducted by Prof. M. Takasaki.

Neutrino Beam Facility

Side View

Neutrino Energy (Monte Carlo)

012Eν(GeV)KEKSK(300m)(250km)3

40

123Eν(GeV)

4

Neutrino Profile (Monte Carlo)

KEKSciFi

SKSK

Mu/Fe10mrad

0210mrad46R(m)

8 10 12012R(km)3