WAO2010
April 12, 2010

Commissioning of J-PARC Main Ring
Tadashi Koseki
Accelerator Laboratory, KEK

Contents:
1. Overview of J-PARC accelerators
2. History of MR beam commissioning
3. Recent highlights of the MR commissioning- Fast extraction and high power operation- Slow extraction
4. Summary

J-PARC : Join project between KEK&JAEA
LinacRCS
Neutrino beams to SK

MLF (Material and Life
science experimental Facility)

JFY 2006 / 2007
JFY 2008
JFY 2009
Birds eye photo in Jan. 2008

Hadron experimentalhall  Main RIng

Construction
StartTime when thisschedule was created(J-PARC Center started)

Start of MLF
User Programs

All the facilities started the beam commissioning on schedule.

Linac• Particle:• Energy:• Peak current:• Repetition:• Pulse width:

90-deg dump

H181 MeV at present
400 MeV by installing ACS in 2012
( Construction of ACS has been started. )30 mA at 181 MeV
50 mA at 400 MeV in the future
25 Hz
0.5 msec
181 MeV

Front-end 50 MeV(7 m)
DTLSDTL(27 m)(84 m)

100-deg dump

Debuncher 2
Debuncher 1

30-deg dump

ACS

3 MeV
Front-end = IS +LEBT+ RFQ + MEBT

0-deg dump

SDTL



RCS (Rapid Cycling Synchrotron)
Multi-purpose machine:- Neutron/muon source- Booster of the MR

To MLFTo MR

4 kW

2009/11/9
Start 120kW Operation

2008/12/23
Start User Program

2008/5/30 : Start BeamCommissioning

History of beam delivery to MLF

20 kW
120 kW
2009 summer shutdown

Before the 2009 summer shutdown, RCS beam power for users was limited at 20 kW due to adischarge problem of the Linac-RFQ. In the 2009 summer shutdown, we improved vacuum
system of the RFQ. --> High power operation of the RCS has became available and 120 kW
operation has started for the MLF users. The RCS has also succeeded to demonstrate a 300
kW operation for one hour in the last December.

Main parameters of MR
Circumference 1567.5 m
Repetition rate ~ 0.3 Hz
Injection energy
3 GeV
Extraction energy 30 GeV(1st phase)
50 GeV (2nd phase)Superperiodicity
3h9
Number of bunches 8
Rf frequency 1.67 - 1.72 MHz
j 31.7 (typical)
Transition 
Number of dipoles
quadrupoles
sextupoles
steerings
Number of cavities

96216 (11 families)
72 (3 families)186
4 in day-oneBeam abort line

Fast extraction

HadronExperimental Hall

Rf cavities

Neutrino beamline

RCSBTcollimators

3-50 BTInjection

Hadron beamline
Slow extraction

Ring collimators

To Super-Kamiokande

Three dispersion free straight sections of 116-m long:- Injection and collimator systems- Slow extractionSX)
to Hadron experimental Hall
-MA loaded rf cavities and Fast extraction(FX) (beam is extracted inside/outside of the ring)outside: Beam abort line
inside: Neutrino beamline ( intense  beam is send to SK)

History of MR initial beam commissioning

Just after the success of30 GeV acceleration

Layout of beam dumps

First stage: 2008/5-6 (~12 days)- May 20:First beam circulation without rf capture- May 22:1000 turns circulation with rf, beam extraction to the injection beam dump
2008 summer/autumn shutdown: 2008/7-11
Second stage: 2008/12- 2009/2 (~26 days)- Dec 23: Acceleration from 3 GeV to 30 GeV and beam extraction to abort beam dump using
fast extraction system.
- Jan 27: Beam extraction to the hadron beam line using slow extraction system.
Third stage: 2009/4-6 (~27 days)- April 23: Beam extraction to neutrino beam line using the fast extraction system.
2009 summer shutdown: 2009/7-9Recent Highlights
1. Fast extraction / high power demonstration

T2K experiment:
Tokai-to-Kamioka(T2K) longbaseline neutrino oscillation
experiment

Goal is discovery of

T2K group has started physics data taking since January 2010.

Intensity

Acceleration

Circulating beam intensity
measured by DCCT for 30
kW operation .

Cycle time = 3.52 sec

injection

1.6 kmSXFXTime [sec]BLM counts

Time [msec]

Integrated beam loss
counts for one shot .

BLM address
BLM address
Beam loss localizes on the ring collimator section. No beam loss during acceleration.

Delivered proton number
on the graphite target

First neutrino event at SK onFeb. 24, 2010.

Courtesy of the T2K groupDemonstration of 100 kW equivalent beam
Tune ( 22.40,20.76)

The extracted
particles to abort
dump is 7.2e13 ppp,
it corresponds to
100 kW if operated
in 3.52 sec cycle.

Time [sec]Not a real beam loss: reflection from the beam dump
Beam loss of 109 during acceleration:
The cause of beam loss is supposed tobe pressure rise.
-> Continuous operation will decrease
the loss

BLM address

Total injection loss is 7.7 e11~105 W < collimator limit 450 W

Recent Highlights
2. Slow extraction

K1.8 (Day-1)
3? (E05): Spectroscopic study of hypernuclei
2? (E13): Gamma-ray spectroscopy of light hypernuclei

1 (E19): Pentaquark search in pK-X

Proton beam of  
Layoutbeam linesat hadron " "      !#experimental
facility in February
2010.

K1.8 (stage-2)(E03): Measurement of X-rays from  Atom
(E07): Double strangeness system
K1.8BR (Day-1)
2 (E15): Search for deeply-bound kaonic nuclear states

1 (E17): Precision spectroscopy of kaonic 3He
K1.1
K1.1BR (stage-1)(E06): Measurement of T-violation in K+0+μ++
High-P (stage-1)(E16): Chiral symmetry in QCD
KL (stage-2)(E14): KL0+
COMET (New beam line, deferred)
μ-e conversion experiment at sensitivity of 10-16

Slow extraction

3Qx=67

FT: 0.7-2.63 sec

Horizontal tune

Measured tune during the tune
ramping by QFNSpill monitor signal in HD beam line
DCCT
Extracted beam has many
sharp peaks.

3Qx=67

Tune fluctuation ~ ± 0.003
The cause is current ripple ofquadrupoles PSs.

Circulating beam intensity [a. u.]

TimeVariation of circulating beam
intensity during slow extraction
for two shots

T2  Idt 0

Time

Because of the tune fluctuation, the circulating
beam decreases in the step-like shape

Duty = TT2

 dt  I dt
00~1%

Improvement of spill structure
Spill feedback using EQ, RQ and DSP system was installed in the 2009 summer shutdown
Beam spill signal is fed into theDSP system and current pattern ofthe correction is sent to PSs offeedback quadrupoles.

EQRQ

EQ: for constant spill structure ( < 100 Hz)

RQ: for ripple compensation ( < 3 kHz)Ripple reduction using trim coil of quadrupoles
All the quadrupoles has trim coils. We set MOSFET RELAY tothe trim coil circuit.
    

Trim coil

FB
Short
Main coil

FT

Trim Coil
Short

Main Coil!

Operation for users in hadron experimental facility
With spill Feedback EQ/RQ+trim coil short

Acceleration

2.4 e12 ppp(1.9 kW at 6 sec cycle)

Extraction

Duty of the spill
Improved from 1 % to 11 %Estimated extraction efficiency ~ 98.5 %+1.8GeV/c

SKS

K+

We have observed
charged and neutral kaonsin the secondary beam lines(K1.8BR, K1.8 and KL) ofHadron Experimental Hall.

+
1.8GeV/c



K
p

By courtesy of the Hadron Gr.

K1.8

K0L+-0KL

K1.8BR
T1 target

30GeV proton beam

Residual activation after RUN#30
After the 2010 February RUN (RUN#30):
Total deliver time to HD is 122 hrs. (5 days) : 1 kW(106.5 hrs.), 2 kW (2 hrs.), 1.5 kW (13.5 hrs.)
Total deliver time to NU is 72 hrs. (3 days) : 18 kW(19 hrs.), 27 kW (21 hrs.), 31 kW (32 hrs.)
Survey: 4 hours after stop of beam delivery to NU, measured by contact on the beam ducts.
( 7days after stop of delivery to HD)
Collimator

SX section

FX section- High activation is localized incollimator section.
- The residual activation in SX
section 1 week after beam stopis less than 100 μSv/h oncontact.
(The guide line of activation
max. is 1 mSv/h to allow hands
on maintenance.)SummaryThe RCS has started to deliver the 120 kW beam to the MLF since Nov.
2009.
Recent achievements of the MR operation:
Fast Extraction (FX)
-Beam delivery to the NU beam line : 40 kW in max.
Physics data taking started in January and 1st neutrino event in SK on Feb. 24.

-High power demonstration : 100 kW equivalent operation
7.2~7.4e13 ppp : the world record of ppp in synchrotron

Slow Extraction (SX)
-Beam delivery to the HD beam line : 2.6 kW in max.
-Tuning for higher extraction efficiency: ~ 98.5 %-Improvement of time structure of beam spill.
Duty of the spill is ~11 % in users operation.

Plan for JFY2010
FX:- Beam delivery of 40 - 100 kW or higher to T2K experiment- New FX kicker system with faster rise time ( # of bunches : 6 -> 8)- Operation with 2nd harmonics cavity
SX:-Beam delivery of 5 kW to HD users-For higher extraction efficiency :Dynamic bump scheme will be adopted from 2010 Autumn RUN- For improvement of spill structure :Main PS tuning to reduce 600 Hz ripple
Feedback with RF noise
Ripple cancellation system     

Correlation between pressure rise and beam loss

Pressure [ Pa]1.2e13ppb6

1.2e13ppb2

Time [sec]The most significant pressure rise is observed in the SX section.

1.2e13ppb2
BLM address
No beam loss during acceleration

TimeAn expected loss from pressure of 1e-3 Pa:~ 1e8 particles/sec (C equivalent)
Measured loss is ~1e9.
The cause of beam loss may be pressure rise.
-> Continuous operation may decrease the loss

Time [sec]1.2e13ppb6 (100 kW eq.)

BLM address
Beam loss at SX sectionExtraction with the spill feedback system
With EQ

With EQ/RQ

Duty ~ 3 %Duty ~ 6 %Extraction with EQ/RQ + coil shortTrim coils of 117 quadrupoles of six families (QFN,QDN,QFX,QDX,QFR,QDR) are shorted
at FT
Without coil shortWith coil short

Duty 6.6%

Duty 8.4%

After additional tuning of EQ/RQ, the duty improved ~11 % with auxiliary coil short.

Extraction with EQ/RQ +Coil short + transverse RF noise(,/01+80#+..322 &8-1', & ' !  
 %.",+ 47&(,/0.-' ,07&(,/01+'& +#0$,#4'When the RF noise switches on, theEQ feedback does not work in thespill end. Investigation of the reason
and more tuning are necessary forthe users RUN.

Calibration of BLMs
Beam loss distribution similar to the SX loss was made using
steering magnets
Distribution of integrated
counts of the BLM signals
To HADRON Hall
shot13286

Local bump at #76
shot13274

Local bump at #82
shot13229

%#' %#*,#('#+ $ 0  /  / 

%(%-&) (++%(%-&) (++%#*,#('-*. %#*,#('-*.  0 /  /-*. 
(%-&) ) $ 

+#"'%)(#',
 ##!#"$#" 

(++)+*,#% +!*(&

-*. 
(%-&) ) $ 

#! $

Beam loss and extraction efficiencyFor high extraction efficiency: - Bump orbit tuning- Position adjusting of ESSs and Magnetic septa- Tuning of resonant sextupole strength
BLM counts

4e11 ppb1 bunch
Injectionsection

1.6 kmSX
section

RF&FX
section

Most of losses localizeon the SX section on theextraction timing

Estimated extraction efficiency
from the BLM counts : ~ 98.5 %It is consistent with the efficiency
measured by SEC in HD beam line(~ 100 % with 10 % error)

Time [sec]BLM address
Ext.
Acc.

BLM address

Ripple cancellation system
All the quadrupole magnets have trim coils.
An additional pickup coils set on the magnet
poles to measure the field ripple.
-> A DSP system gives the ripple cancellation
signal to the trim coil.

%!

Noise canceling headphones

Measure the ripple
 &"%!!'    ($%"#"))DSP

Feed-back/Feed-forward))))


Ripple cancellation
using Trim Coil

Power upgrade plan for the fast extraction
For 8 bunches, 30 GeV at MR: PMR=1.6 x (PRCS/ TMR)RCS POWER FOR MR6sec (2.7%)

Linac energy upgradenow

3.52sec(4.5%)

0.72MW

3.2sec
(5.0%)MR POWER AT 30GeV
2.47(6.5%)

MR CYCLE [sec]BEAM POWER [MW]( ): Beam transfer ratio from RSC to MR

2.23sec (7.2%)(maximum cycle withexisting power supply)
1.0sec (16%)

2008
H20

2009
H21

2010
H22

2011
H23

2012
2013
2014
2015
H24
H25
H26
H27
ACS Installation in JFY2012
JFY
400 MeV injection in the RCSPower upgrade plan of SX (under discussion)

Power and spill after the summer shutdown
Beam intensity

Spill structure

JFYKeycomponents

Users operation[kW]Accelerator
study
[ kW]

Key components

2010

Dynamic bump510

Feedback system
Ripple canceller

2011

SX collimator
Ti chambers
Local shields

1020

RQ Power supply

2030

30> 30> 30

20122013
2014

Duty
[%]

30> 30