IBIC2012
International Beam Instrumentation Conference
Tsukuba, Ibaraki, JAPAN, 1st to 4th, Oct. 2011

Progress of Beam
Instrumentation in J-PARC Linac
Akihiko MIURA
with the Beam Monitor Group inJ-PARC

Progress of Beam Instrumentation in J-PARC Linac
Contents

1. Introduction
2. Commissioning Tools for 181 MeV Operation
3. Development for Energy Upgraded Linac
4. Diagnostic Devices for Beam Physics
5. Damage and Recovery from the Earthquake21. Introduction
Main Parameters of Linac
Ion species: Negative hydrogen ion
RF frequency: 324 MHz (972 MHz for ACS cavities)
Output energy: 181 MeV(to be increased to 400 MeV by adding ACS cavities)
Peak current: 30 mA (50 mA)
Pulse width: 0.5 msec
Repetition rate: 25 HzChopper beam-on ratio: 56 %Beam power: 36 kW (133 kW after 400 MeV upgrade)31. Introduction
Beam Instrumentations
Commissioning Tools for 181 MeV Operation
BPM: Beam Position Monitor
BLM: Beam Loss Monitor
SCT: Current Monitor (Slow Current Transfer)
FCT: Phase Monitor (Fast Current Transfer)
WSM: Profile Monitor (Wire Scanner Monitor)
Development for Energy Upgraded Linac (400 MeV)
Scintillation Beam Loss Monitor (X-ray less sensitive)
Longitudinal Beam Profile Monitor (Bunch Shape Monitor)
Non-destructive Profile Monitor (Laser-based)
Diagnostic Devices for Beam Physics
Beam Loss Track Measurement
Measurement of H0 / Intra-beam Stripping (IBSt)
4

Progress of Beam Instrumentation in J-PARC Linac
Contents

1. Introduction
2. Commissioning Tools for 181 MeV Operation
3. Development for Energy Upgraded Linac
4. Diagnostic Devices for Beam Physics
5. Damage and Recovery from the Earthquake52. Commissioning Tools
Commissioning Tools
BPM: Beam Position Monitor
SCT: Slow Current Transformer (Current Monitor)
FCT: Fast Current Transformer (Phase Monitor)
WS: Wire Scanner Monitor (Trans. Profile Monitor)
BLM: Beam Loss Monitor
Future ACS
MEBT
17 BPM
DTL&SDTL
8 BPM
3 SCT
29 BPM
6 SCT
4 FCT
18 SCT
5 FCT
4 WS
47 FCT
4 WS
30 BLM
4 WS
4 BLM
Front-end
53 BLM(7 m) DTL
SDTL
Future ACS(27 m)(84 m)

3 MeV 50 MeV

181 MeV

Debuncher 1To RCS

L3BT & dumps
48 BPM
11 SCT
5 FCT
24 WS
38 BLM
L3BT

Debuncher 262. Commissioning Tools
Beam Position Monitor (BPM)

Quadrupole Magnet

Strip-line type is employed.
ResolutionΔx<~0.1 mm
Δy<~0.1 mm+y+x-x-y

Beam line

Beam Position Monitor
72. Commissioning Tools
Beam Current (SCT: Slow Current Transformer)
Phase Monitor (FCT: Fast Current Transformer)
Laser Tracker(Corner Cube Reflector)

Annular magnet core “FINEMET” is employed forthe current transformer.
FlangeDynamic Range
SCT: 0.1 – 80 mA
FCT: > 30dB

Resolution,
SCT: ΔIbeam < 1.0 %,Imin ~ 0.1 mA
FCT: Δφbeam < 1.0 deg.
Energy: < 0.1 %Outline

BeamCross
SectionWinding coil,
SCT: Fifty turns
FCT: Single turn

CeramicBreakFINEMET
Core forFCTFINEMET
Core for
SCT82. Commissioning Tools(e. g. at SDTL03)

Energy Measurement, Phase Scan
Beam energy is measured with the aid of FCT
based on the TOF (Time-OF-Flight) method.

Line: Simulation
Point: Measured ValueL
BeamCavity∆
Phase Delay

Difference of Phase DelayK[MeV] = m0 (- 1)
 = 1/sqrt(1-), =L / (t・c)
t [sec] = / (360 x 324 MHz) [deg.] = FCT1 – FCT2 ± (n x 360 )Klystron
(N)
A

(N)
B

EnergyFCT2FCT1(N+1)
A

(N+1)
B

(N+2)
A

(N+2)
B

Long TOF pair apart by 21 

Phase: 0 to 360 deg.

Phase Set Point
In order to seek an adequate set-point,matching is implemented by the phase scan.
The set-point is determined from the best
matching point between the measurement
and model simulation.
92. Commissioning Tools
Comparison of the Performances Between FCT and BPM
Measured performance data of FCT and BPM using network analyser areshown. Measured signal level is corresponding to 82 mV for FCT and 25 mV for
BPM respectively. Signal level from FCT is three times higher than that fromBPM.

Yellow: Reflection of the input RF
Water: Response from FCTYellow: Reflection of the input RF
Water: Response from BPM

324MHz324MHz

Performance of FCT

Performance of BPM

102. Commissioning Tools
Beam Loss Monitor (BLM)
Sensitive for charged
particle, X-ray andgamma-ray

SDTL Cavity

Quadrupole Magnet

Beam line

Fast time response
It is enough fast toalarm the protection
system.
Gas Proportional BLM, E6876 - 600
 < 1.0 sToshiba Electron Tubes & Devices Co. Ltd.,

Length: 600mm
Diameter: 50.8 mm
Gas pressure: 1 atm

Anode Pt Wire,Φ50um(Gas: Ar+CO2)

Gas Proportional Counter

Scintillation Monitor

112. Commissioning Tools
Beam Loss Measurement
125 BPMs are delivered in the beam line.
Beam loss profile at 20 kW operation Jan., 13, 2009, Run 21.
Around Bend Magnet

BLM of L3BT21
BLM of ACS14B

DTL

SDTL

Future ACS

To 0 deg. dump
To 100 deg. dump

L3BT

X-ray emitted from the SDTL cavities is detected by the BLM.
---> Suppression of X-ray noise should be considered using another detector.
122. Commissioning Tools
Beam Profile Monitor(WS: Wire Scanner)

haloSDTL03A

Range

Motor Unit
45 deg.

Horizontal Profile

Example of Transverse Profile

Tungsten
Wire

Four WSs are located in each matching section periodically.
Dynamic range reaches four orders.

Pulse HeightResolution
σx < 0.1 mm
σy < 0.1 mm

CarbonPlate forVerticalBeam Size
Ceramic Frame

200 mV/div, 40 us/div

Signal Obtained at the Peak ofBeam Pulse
13

2. Commissioning Tools
Transverse Matching

After matching of collimator section,June, 6, 2008 (Run 16)

WSs are located periodically.
Quadrupole magnets located before the WSs are tuned to have the same beam width at
the wire scanner locations.
Pink: Vertical (x)Blue: Horizontal (y)Pink and blue lines are the simulated beamenvelope evolution.
These are referred to find the adequate set
values of the quadrupole magnets.

[m]

L3BT
Straight
Matching
section

L3BT
Collimator
Matching
sectionZ-axis (Location)

L3BT
Injection

Peak current
5 mA

2. Commissioning Tools - unique application
SDTL Longitudinal Acceptance
Simulation indicates the acceptance has enough margin to beam profile,
however we have to check- actual acceptance is as large as simulation or not.
- the actual acceptance margin is enough for beam profile or not.
Measure the acceptance on s direction by phase scan, in which we change thedriven phase of all SDTL cavities, we take beam transmission through SDTLs.
As the results, acceptance has enough margin for the beam.
Experiment

Simulation

30 deg55 degBeam transmission by SCT : Beam core information
Beam loss by BLM : Beam halo information

15

2. Commissioning Tools - unique application
H0 Particle Measurement
H0 was observed with a wire scannermonitor at the straight beam dumpwith bending magnet on.
DipoleH- beammagnet B
H0Wire scannermonitor0-degree
beam dump

16

2. Commissioning Tools - unique application

CT Wave Form

All beam pulse is kicked by the tuned phase of RF chopper.
Wave form disappeared in the CT signal.

0.3

Height of Kicked Pulse

Chopper Tuning

Optimized phase can betaken by the hyperbolic
approximation.

-40(a) Before Kicked(b) Kicked by Detuned
Chopper(c) Kicked Beam

0.2
0.1

-20

02040

-0.1
-0.2

Beam Pulse by WS-0.3

Scans of RF Phase --- Optimization(a) Kicked by Detuned
Chopper. Beam pulse
still remains.

(b) During Phase
Scanning. Small beampulse still remains.

(c) Kicked by TunedChopper. No beampulse remains.

Phase [deg.]
This level is corresponding
to the 1/1000 of usual
pulse height.

Wave form taken by WS.
Over 100 shots are averaged.
17

Progress of Beam Instrumentation in J-PARC Linac
Contents

1. Introduction
2. Commissioning Tools for 181 MeV Operation
3. Development for Energy Upgraded Linac
4. Diagnostic Devices for Beam Physics
5. Damage and Recovery from the Earthquake18

3. Development for Energy Upgraded Linac
Scintillation Beam Loss Monitor (under study)
Gas proportional BLM is sensitive to X-ray from the cavity.
The plastic scintillation monitor with less X-ray
sensitivity is employed to measure the beamloss.

Yellow: S15_SCT01
Pink: S13B_Scintillator
Green: S13B_BLM
600us

Clear beam loss signals with low noise is
successfully measured and the high time
resolution of the beam loss is confirmed.
Beam (CT)
40ns

SHV
Plastic Scintillator

Photo-multiplier

160ns

160ns

Scintillator

600ns

BNC

Photo-multiplier: Hamamatsu H3164-10(gain : 1.1 x 106, peak wavelength : 420 nm)
Plastic scintillator: Saint-Gobain BC-408(peak emission wavelength: 425 nm)

Proportional19

3. Development for Energy Upgraded Linac
Beam Loss Measurement at DTL Section
Higher residual radiation was recognized at the surface of drift tube linac(DTL) cavity.
Scintillation beam loss monitors are installed at some points with particularlyhigh radiation to investigate the cause of the radiation.
Although the DTL section is low energy part of the linac, fine structure of thebeam loss was observed by the scintillation BLM.
We measured the beam loss occurred at the DTL varying the beam orbit.

Yellow: Beam Current
Purple: Beam Loss (+x direction)
Green: Beam Loss (-x direction)

Yellow: Beam Current
Purple: Beam Loss (+x direction)
Green: Beam Loss (-x direction)

Beam orbit is corrected.

Beam orbit is slightly shifted.

20

3. Development for Energy Upgraded Linac
Bunch Shape Measurement for Energy Upgraded Linac
Three bunch shapemonitors are installed inorder to tune thelongitudinal matching,because the different
acceleration frequency isemployed between SDTL
(324MHz) and ACS(972MHz).
Installation

Position of BSMs in ACS Section
BSM
Buncher 1

SDTL16

Buncher 2

MEBT2

BSM

BSM

Assembling & Tuning in Test Bench

WSM

WSM

WSM

WSM

ACS01

ACS02

ACS03

ACS04

21

3. Development for Energy Upgraded Linac
Non-destructive Profile Monitor (Laser-based)

Beam current isdecreased to 90%.

Photo detachedelectron signal

Signal from MPT(Laser timing)

Laser beam is injected into MEBT1 horizontally.
Good S/N ratio, stable signal was observed.
The feasibility of Laser profile monitor was clearly demonstrated.
22

Progress of Beam Instrumentation in J-PARC Linac
Contents1. Introduction
2. Commissioning Tools for 181 MeV Operation
3. Development for Energy Upgraded Linac
4. Diagnostic Devices for Beam Physics
5. Damage and Recovery from the Earthquake23

4. Diagnostic Devices for Beam Physics
Recent Topics: Measurement of Intra-Beam-Stripping
For the continual beam operation, a major operation goal isthe decrease of beam loss.
It has been recently suggested that intra- (H-) beam-stripping
contributes significantly to beam losses in an H- linac.
In LINAC2012 conference (held at Tel-Aviv at sept. 9 – 14.)
Contribution of intra-beam-stripping was tested experimentallyat SNS by accelerating a proton beam with an inverse optics.
SNS presented that the experimental analysis results are ingood agreement with the theoretical estimates with emphasis
on understanding beam loss in terms of intra-beam-stripping.
V. Lebedev, LINAC10, THP080
J. Galambos, LINAC12, MO2A02

24

4. Diagnostic Devices for Beam Physics
Recent Topics: Measurement of Intra-Beam-Stripping
Electron Detector

Faraday Cup

H- → H0 + eFaraday Cup orElectron MultiplierElectronpppp

BeamH‐p

電磁石H0 Particlep

DipoleMagnet25

4. Diagnostic Devices for Beam Physics
Proton Track Measurements with Scintillating Fibers
Count the number of H+ from H0 (residual gas interaction)
One H+ corresponds to one lost HReconstruct a track passing through all fiber planes
Energy measurement with time of flight
By fiber positions, emission point can be measured!

Beam loss distribution along beam duct: “Protontelescope”

H. Sako, IPAC2011, MOPS078
H. Sako, LINAC12, TUPB082

26

4. Diagnostic Devices for Beam Physics
Proton Track Measurements with Scintillating Fibers
We measured charged particle tracks
using scintillating fiber detectors
with a fast trigger scheme.
Clear time-of-flight peaks of protons,
which are consistent with protonenergies in the simulation.

Upstream
detector
supportHorizontal
StrokeDetectorposition

Downstream
detector
support

Vertical
StrokeDetector is upgraded!
Addition: both horizontal and verticaltracks reconstruction
Remotely-controlled detector: moving
system (horizontal and vertical)
Detector System Upgrade27

Progress of Beam Instrumentation in J-PARC Linac
Contents

1. Introduction
2. Commissioning Tools for 181 MeV Operation
3. Development for Energy Upgraded Linac
4. Diagnostic Devices for Beam Physics
5. Damage and Recovery from the Earthquake28

5. Recovery from the Earthquake
The East Japan Great Earthquake

K. Hasegawa, IPAC2011, WEPS095
K. Hasegawa, LINAC12, FR2A01

The great earthquake occurred on March 11, 2011.
The seismic intensity: 6-minus (JMA scale) at J-PARC.
Although Tsunami hit the Tokai-site coast, the height was fortunately below the floor
level of J-PARC.

J-PARC

Entrance of the Linac
Seismic Intensity (Data fromNational Research Institute).

About 1.5 m drop over a wide area.
All electric wires and water pipes were damaged.
29

5. Recovery from the Earthquake
Flooding at the Linac Tunnel

Corroded pre-amplifier boxes on
the floor by strong alkaline.

Inside of underground tunnel

10cmGroundwater leaked into the tunnel: depth of
10 cm (150 tons) within two weeks

Some flooded pumps were broken.
30

5. Recovery from the Earthquake
Subsidence of the Tunnel

T. Morishita, IPAC2011, WEPS049
K. Hasegawa, LINAC12, FR2A01

Subsidence: 40 mm (DTL and SDTL section) and 20 mm (now BT, future ACS section)
Continued floor elevation change by June: precise alignment carried out after that.

40mm20mm

Floor subsidence by the earthquake

Floor level change byJune, 201131

5. Recovery from the Earthquake
Damage of Beam Monitors and Bellows
Distorted bellows between SDTL tanks

Bellows andmonitors could notstand for theseflexibilities andbroken.

A. Miura, IPAC2011, WEPC144
K. Hasegawa, LINAC12, FR2A01

Broken current transformer

Detouchment of thebrazing section
between the ceramic
tube and stainless duct32

5. Recovery from the Earthquake
Summary
Numbers of Installed and Damaged Monitors
SectionNumber

BPM withBellows

SCTFCT

MEBT1

Installed865Damaged100Installed033

Damaged022

Installed

32

1544

Damaged6017DTLSDTL

About one-thirds of FCT monitors had damaged in SDTL section.
All damaged monitors had been exchanged until the end ofNovember, 2011.
Beam commissioning started from December, 2011.

33

Summary
We employed following monitors as commissioning tools:
Strip-line type beam position monitor,
Gas proportional beam loss monitor,
Slow / fast current transfer as the current / phase monitor, andWire scanner for beam profile measurement.
For energy upgraded project, we developed
Scintillation beam loss monitor (X-ray less sensitive),
Bunch shape monitor for longitudinal profile measurement andLaser-based non-destructive profile monitor.
For the increasing of output energy, key word is a “intra-beamstripping (IBSt)” as the cause of beam loss.

34

Acknowledgements
J-PARC Monitor GroupWe thank to following researchers and engineers for their efforts andkind advice.
Linac
A. Miura, T. Miyao
RCS: Rapid-cycling synchrotron
K. Yamamoto, N. Hayashi, M. Yoshimoto, H. Harada, S. Hatakeyama, R. Saeki
MR: Main Ring
T. Tokaya, M. Teshima, S. Lee, K. Sato, Y. Hashimoto, M. Okada
Linac Commissioning Group & Supervisors
M. Ikegami, H. Sako, T. Maruta, J. Tamura, K. Futatsukawa,
H. Oguri, N. Ouchi, F. Naito, K. Hasegawa

Thank you!
We welcome you to visit J-PARC.
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