Proton Beam for K2K
Hiroyuki Noumi (KEK) for BCG andK2KContents• Beam Line Layout• Primary Beam Characteristics- Time Structure/Emittance/BL Optics• Proton Beam Monitors- SPIC/LS, CT/SEC• Operations- Transmission- Beam tuning• SummaryBeam Line Layout

Primary Beam Characteristics
Acceleration (0.5GeV to 12 GeV)MR Intensity

Injection(9 bunches)

1-turn ExtractionTime
2.2 sec repetition

Primary Beam Characteristics- Time Structure•12-GeV Proton Fast Extracted Beam

ADC Gate

CT signal~1 µs

fRF = 7.9 MHz
Ibeam = 5.6E12 ppp

Primary Beam Characteristics- Emittance• ε：Measured Emittance (FW1/e2M) in mm・mrby Parabola Fitting Method at q11-in (31m from Extraction)
εV = 8π
Wy2 (cm2)Wx2 (cm2)εΗ = 13πg (kG/cm)

g (kG/cm)

Beam Line Optics- Beam Envelope

Beam Line Optics- Acceptance & Beam Profile @ q11-in
・TURTLE13πmm・mr

8.4πmm・mrProton Beam Monitors

400m

350m
0m
70m

208m

Proton Beam Monitors- SPIC/LS/CT• Profile Monitors
SPIC：Segmented parallel Plate Ionization Chamber
LS: Luminescence Screen (Cr-doped Almina Ceramic Plate)• Intensity Monitor
CT: Current Transformer
SEC: Secondary Emission Chamber (for Suppｌiment)Beam Monitors- SPIC/LS/CTSPICLSCT

Monitors in the Beam Pipe

Beam Monitors-at the Production Target
Target HORN
SEC
SPIC

SPICCT
BeamLS
Monitors on the Slide TableOperations- Transmission• at Extraction○ Vacuum Window (300µm Ti foil)○ 5 m Air in Septa○ Fixed Beam Monitors (SEC/SPIC/LS/SUS foils)
cause
6-8% Beam Loss & ×3-4 Emittance Growth• Transmission
TGT/Ep1-in = 0.85 w/ full of Monitors in the BL~5% improved when ½ of LSs (~2.5g/cm2) out

Operations- Beam Tuning

Tuning Routine• Steer the Beam Orbit to the Beam-Line Center
1st Beam Dump Mode
Arc Transfer Mode
• Targeting
Direct ν-Beam to Super-K
Muon Profile is Sensitive to the Primary beam(work as a proton-beam monitor)

Operations-Proton Beam Profile
SPIC at the Target

LS at the Target

Viewer @ TGTHornSPIC

Elevation View of T-Station & µ-pitµ-pit

Muon Monitors in the µ-pit

Operations-νµ (Muon) Response (Cont.)• Muon Profileat the Muon Pit

Operations-νµ (Muon) Response• Horn Lens System (Point to Parallel Optics)
Concept of the Horn Lens System

×-100

v39
SPIC

TGT
SPIC

MagneticHornμ-Monitor
at Muon Pit

The Horn functions as a lens with the Magnification of 〜 -100.

Operations-νµ (Muon) Response (Cont.)

Operations-Tuning Request in 2001•

Tuning Request○ Scheduled- at the beginning of every run (~4 weeks),- after the MR study/Tuning,- at the Ion Source Maintenance○ Accidental (User Claimed)
2 times in 2001 (10th Jan ~ 12th Jul, 5 runs),
1…Beam Shift/Drift
1…Transmission Down
were found to be caused byfailures of the current-readout in Mag.-PS(▼ 7 times in 2000, due to beam shift/drift)Beam Shift/Drift in 2001
MuonCentroidDriftin
1 day

Horizontal-1mradVertical+1mrad

Beam Shift/Drift in 2000µ-X Profileµ-X① ②µ-X③① before shift② shifted
Beam shifted
Recovered after 33 hours③ recovered2mSummary• Fast Extracted Proton Beam
Ibeam >6e12ppp@Extraction, 5.6e12ppp@T-station
εH/V ~ 13π/8π mm・mr (FW1/e2M)• Proton Beam Monitors
30 SPICs/LSs…Beam tuning/monitoring
16 CTs…Intensity(Transmission) & Time Structure• Operations
Tuning Routine…Steer Beam & Targeting
Only 2 accidental tuning requests in 2001
Very Stable!
Muon monitor is a high-precision proton-beammonitor.