1. Accelerator Overview for HI program in J-PARC
Hiroyuki Harada, Pranab Kumar Saha, Michikazu Kinsho
J-PARC/JAEA
Reimei Workshop "Physics on Heavy-Ion Collisions at J-PARC“
August 8th 2016

2. J-PARC (JAEA & KEK) 1 MW 0.75 MW Neutrino Beam Line to Kamioka (NU)
400 MeV H- Linac
3 GeV Rapid Cycling Synchrotron (RCS)
Materials & Life Science Facility (MLF)
Neutrino Beam Line to Kamioka (NU)
50 GeV Main Ring Synchrotron (MR)
1 MW
0.75 MW
Hadron Experimental Hall (HD)
JFY 2006 / 2007
JFY 2008
JFY 2009

3. HI Accelerator scheme in J-PARC (preliminary)
proton (existing)
HI booster
U35+→U66+
20  67 AMeV
U66+→U86+
61.8 AMeV
stripping
HI Linac
U35+
20 AMeV
HI (under planning)
Figures: Not to scale
U92+
0.727  AGeV
p/HI to HD
p to HD MR
330 GeV (p)
MLF
RCS
(H-  p)
0.4  3 GeV
U86+
61.8  AMeV
U86+→U92+
0.727 AGeV
stripping
p to NU
H- Linac: 0.4 GeV

4. HI linac & Booster

5. 3GeV Rapid Cycling Synchrotron (RCS)
Inj. Ins.
Ext. ins.
Acc. Ins.
Arc
MLF :
　　Material & life science facility
MR :
　　50GeV Main Ring synchrotron
Injection
　 time (ms)
0.28
0.93
1.13
B (T)
Excitation curve of main mag.
LINAC
Rep. ：25Hz
400MeV
Extraction
3GeV proton beam
3GeV
20ms
Acceleration
Circumference
： m
H- beam from
400 MeV LINAC
field
Mid. pulse
time (ms)
0.5ms (307turns)
H- charge exchange
Multi-turn injection
456ns
814ns
Injection energy : 181MeV → 400MeV (2013)
Number of particles : 5× → 8.3×1013 (2014)
Beam power 　 : 300kW → 1.0MW

6. RCS beam study results for high intensity proton
Courtesy: H. Hotchi
― 8.45 x 1013 ppp : 1014 kW-eq.
― 7.25 x 1013 ppp : kW-eq.
― 6.09 x 1013 ppp : kW-eq.
― 5.05 x 1013 ppp : kW-eq.
― 3.94 x 1013 ppp : kW-eq.
BLM signal(arb.)
time (ms)
Oct. 2015
Injection
Loss ＜ 0.1%
Time (ms)
Particles /pulse (x 1013)
Circulating beam intensity measured by a CT
Jan. 2015
Injection
Extraction
8.41 x 1013 ppp : 1.01 MW-eq.
6.87 x 1013 ppp : MW-eq.
4.73 x 1013 ppp : MW-eq.
7.86 x 1013 ppp : MW-eq.
5.80 x 1013 ppp : MW-eq.
● Successfully demonstrated acceleration and extraction of
1 MW-equivalent beam power (8.4x1013 ppp).
● Beam loss at 1 MW: only 0.1% at beam injection
-- mostly due to the foil scattering.
● Simulation reproduces well experimental results
Demonstrates a potential to achieve a rather high intensity HI beam too!
Realistic simulation of HI beam in RCS

7. A potential of high intensity beam
3rd
Main Ring
~ Typical SX operation
4th
MR user operation :
MR FX : ~21×1013 ppp, MR SX : ~4.6×1013 ppp
A potential of high intensity beam
2nd
1st
Injection
Acceleration
Slow Extraction
Circumference m
Cycle time sec for SX
2.48 sec for FX
Injection energy 3 GeV
Extraction energy 30 GeV
Super-periodicity 3
Harmonic number 9
Number of bunches 8 ( 4 times injection)
Target beam power 100 kW for SX
750 kW for FX

8. Extraction efficiency : 99.54% The highest level in the world
MR SX operation
Injection
Acceleration
Slow Extraction
＜RUN 69 (Jun 2016)＞
Intensity : 4.6×1013 ppp
Extraction efficiency : %
Duty factor : 52.2 %
99.6
Extraction efficiency[%]
Duty factor : 52.2 %
Spill target
Extraction efficiency : 99.54%
The highest level in the world
Jun 24th to 26th , 2016
99.4

9. Requirements of Accelerator in J-PARC
No confliction with other proton programs (MLF/NU)
Reduction of space and budget (by using RCS and MR)
Variable ion species (p, Li, C, Si, Ar, Cu, Xe, Au, U etc.)
Variable beam energy (1 – 19 GeV/u for U)
High beam intensity/rate (1011 per cycle)

10. How HI scheme works in RCS
RCS beam delivery cycle
MLF (p) MR (p/HI) MLF (p)
40ms
• • •
5.52s
PB pattern
25Hz
● MR operates either for NU or HD
When MR operates for HD (5.52s), No. of RCS cycles in 1 MR cycle: 25×5.52 = 138
● Only when MR runs HI for HD, RCS injects HI in the MR cycle.
No conflict with MLF/NU
Limits magnetic field patterns of main magnets

11. Bending and quadrupole magnets of RCS for HI beam
Bending and quadrupole magnets have the same performance (bending angle and focusing strength) by keeping the same “Br” of 400MeV proton beam.
p : momentum [GeV/c]
e : charge
B : magnetic field [T]
ρ : curvature radius [m]
free
fix
+1(proton)/+86(U)
Particle
Inj. Energy
[MeV/u]
Momentum [GeV/c] Br
[Tm]
Ext. Energy
proton
400
0.954
3.182
3000
3.825
12.76
U86+
61.8
82.1
735.4
329.0
No problem for injection, acceleration and extraction in RCS

12. What’s difference between proton and HI
Charge state
Full stripping / multi charge state
Beam loss source
Space charge, instability and gas interaction
Injection scheme
H- charge exchange multi-turn injection /
Bump orbit sweeping injection

13. Charge state of HI beam 86+ Carbon Charge state depends on Beam energy
Material of foil/Gas
Density of foil/Gas
Equilibrium charge
83+ N2
U66+
U86+
U92+
Facility : Riken
Ion : U
Energy : 50MeV/u
Foil/Gas : Carbon, N2, Ne
Density 71 76 81 86 91
82+ Ne
Booster injection
RCS injection
MR injection
Fraction
Courtesy: H. Kuboki
charge

14. What’s difference between proton and HI
Charge state
Full stripping / multi charge state
Beam loss source
Space charge, instability and gas interaction
Injection scheme
H- charge exchange multi-turn injection /
Bump orbit sweeping injection

15. Beam loss source ~ electron stripping
Charge state of U
Injection energy of U
Extraction energy of U
HI LINAC
35+ -
10-20 AMeV
HI Booster
66+
67 AMeV
RCS
86+
61.8 AMeV
735 AMeV MR
92+
727 AMeV
11.15 AGeV
Facility
Particle
Vacuum pressure
J-PARC RCS
proton
~1×10-8 Torr (~10-6 Pa)
GSI SIS18
U28+
1.8×10-11 Torr (~10-9 Pa)
BNL Booster
Au33+
3.0×10-11 Torr (~10-9 Pa)
BNL AGS
Au77+
2.0×10-8 Torr (~10-6 Pa)
Source : FAIR homepage
Courtesy : D. Dinev, W. Fischer
Au77+→Au31+
Beam loss and lifetime are dominated by the electron stripping process due to vacuum pressure.
HI beam w/ high charge state is no problem like AGS.
Almost “Au31+“ beam were lost in AGS
with low pressure level of 10-6 Pa
Beam BNL Booster

16. Estimation of vacuum pressure related beam loss(1)
Special thanks for suggestions:
Manfred Grieser, Max-Planck Inst.
H. Imao, RIKEN
Mechanisms: (1) Electron capture, (2) Electron loss ….
Electron capture cross section: (Schlachter’s formula, Phys. Rev. A 27, (1983)3372)
sc = 1.1×10-8 (Zi3.9×Zt4.2/Ei4.8)
where, Zi and Zt are HI and target (gas molecule) charge numbers, respectively. Ei is the HI mass in keV/u.
sc = 2.752×10-20 cm2 (For N2 at inj.)
Electron-loss (stripping) cross section: (Modified Bohr’s formula)
σ 𝑠 =4π 𝑎 𝛼 2 𝛽 𝑍 𝑡 2 + 𝑍 𝑡 + 𝑞 𝑖 𝑍−1 𝐼 0 𝐼
Where, qi is the ion charge state (86), z is the ion chare (proton number = 92)
a0 = Bohr radius = 0.529×10-10 m, a = fine structure constant = 1/137
b = relativistic parameter = at injection, Zt = charge of residual gas atom (Z = 7 for N)
I0 electron ground state energy = 13.6 eV, I is the binding energy of remaining 6 electrons in different orbital shell
ss = 3.34×10-20 cm2 (For N2 at inj.)
Ion beam lifetime:
t = 1/(s*n*v)
s= cross section, n = residual gas density
and v = ion beam velocity
E(GeV/u) b g
Pgas(Pa)
sc (cm2)
tc (s)
ss (cm2)
ts (s)
ttot (s) N2
0.0618
0.3473
1.0664
10-6
2.752E-20
14.44
3.34E-20 12
6.5
0.735
0.8293
1.7894 ,,
1.898E-25
8.8E5
5.85E-21 28 H2
7.766E-24
5.12E4
1.19E-21
334
332
5.355E-29
3.11E9
2.09E-22
796

17. Estimation of vacuum pressure related beam loss(2)
For N2 with 10-6 Pa
Beam loss:
(Upper limit by using ttot at injection energy)
∆𝑁 𝑁 =1− 𝑒 −( 𝑡 𝜏 )
DN (Beam loss) = 0.31%
Precise estimation:
(summing up turn-by-turn)
∆𝑁 𝑁 =1− 1 𝑛 𝑒 −(∆𝑡 ∆𝜏)
DN (Beam loss) = 0.12%
Beam losses at 10-6 Pa level are acceptable level by using high charge state.
Courtesy: P.K. Saha

18. Beam survival and intensity of HI Beam
● Limits magnetic field patterns of RCS’s main magnets for parallel operation of MLF and MR/HD
● RCS operating set : 1MW proton operation
● Beam survival > 99.95% even for 1.1×1011/b
of U86+ ions
● No any unexpected beam losses
● Beam losses are localized at ring collimator.
Courtesy: P.K. Saha
U86+: 1.1×1011 stripping at 3-50BT  U92+: ~1×1011/RCS cycle
4 RCS cycles injection into the MR: 4×1011 /MR cycle!

19. What’s difference between proton and HI
Charge state
Full stripping / multi charge state
Beam loss source
Space charge, instability and gas interaction
Injection scheme
H- charge exchange multi-turn injection /
Bump orbit sweeping injection

20. Injection system for proton beam
H- multi-turn injection system for high-intensity proton beam
In principle, this scheme
Different motion equation between injected and circulating beam
Multi-turn injection in same phase space for transverse plane
No limitation for the number of injection turns
In principle, this scheme cannot be used for heavy ions injection.

21. Injection scheme for HI beam
Same motion equation between injected and circulating beam
Degrease a bump-orbit height to avoid circulating beam hitting at SEP mag.

22. Beam accumulation in SIS18
Injection inefficiency for tune
Example: SIS 18
Courtesy: S. Appel (ICAP 2012)
w/o SC
w/ SC
Minimum beam injection
~ 40%
Septum
apr.
<SIS 18>
Injection turns : ~20 turns
Min. beam loss : nx = 4.28
<Limitation>
injection turns, intensity, ring optics (tune)
A new injection scheme for high intensity HI beam!

23. World record intensity
3.2×1010 ppp
High intensity (>1011) of HI beam is very challenging in the world.

24. HI Accelerator scheme in J-PARC (preliminary)
proton (existing)
HI booster
U35+→U66+
20  67 AMeV
U66+→U86+
61.8 AMeV
stripping
HI Linac
U35+
20 AMeV
HI (under planning)
Figures: Not to scale
U92+
0.727  AGeV
p/HI to HD
p to HD MR
330 GeV (p)
MLF
RCS
(H-  p)
0.4  3 GeV
U86+
61.8  AMeV
U86+→U92+
0.727 AGeV
stripping
p to NU
H- Linac: 0.4 GeV

25. HI LINAC and HI Booster Ring
Inj. beam parameters for RCS:
Inj. turn
No of bunch
Intensity
(×1011)
Beam
shape Ds
(ns)
Dp/p
(%)
etr
(p mm mrad) 1
1.1
Gaussion
1180
±0.9
100
HI LINAC
HI LINAC and HI booster ring are put into same building
- Advantage of location and cost reduction
Variable
Ion species
extraction energy
extraction beam parameters for RCS
etc.
HI booster
周長：159.6m
Building
50m

26. HI Booster Ring ~ Ring Optics
Beta function
bx,by[m]
Insertion
Arc
Dispersion
hx,hy[m]
Arc
Ins.
Arc
Ins.
Arc
Ins.
Arc
Ins.
Circumference m
Super-periodicity 4
Inj. Energy of U 20 MeV/u
Ext. Energy of U 67 MeV/u
Number of BMs 16 (22.5 Deg.)
Number of QMs 60 (5 series)
Number of SMs 32 (4 series)
Number of OMs 8 (1 series)
Horizontal tune
Vertical tune
Operating point = (4.28, 2.34)
Structural resonance(1~4th)
Nonstructural resonance of 2nd.
Nonstructural resonance of 3rd.

27. Circulated charge state Corresponding to Dp/p0:±3%
Injection scheme for high intensity in HI Booster Ring
To realize high-intensity HI beam, beam accumulation is very challenging.
Propose a new injection scheme, which is charge exchange multi turn injection
U35+(20AMeV)
U35+
U35+
Dump
Gas-jet stripper
Injection septum
Dump septum
U66+
U66+
Components :
Injection septum
Dump septum
Charge exchange device (Gas-jet)
Circulated charge state
Fraction
Charge state
Innovative Injection scheme
⇒　No limits for injection turn
⇒　> 10 times higher than others
Corresponding to Dp/p0:±3%

28. HI injection system ~ charge exchange multi-turn
Injection point
Dump point
bx,by[m]
Charge exchange
U35+→U66+
hx,hy[m]
Gas jet
Quadrupoles
（Up:F, Down:D）
Bending
(θ=22.5Deg.)
Injection septum
Dump septum

29. HI injection system ~ charge exchange multi-turn
Injection septum
Gas jet
Dump septum
Injection point
Dump point
U35+ : x=+255mm
U35+ : x=+255mm
Aperture clearance :
> 200 mm
No hits to Septum
U64+ : x= mm
U65+ : x= mm
U66+ : x= mm
U67+ : x= mm
U68+ : x= mm
x[m]
Charge exchange
U35+→U66+
Quadrupoles
（Up:F, Down:D）
Injection septum
Dump septum
Bending
(θ=22.5Deg.)

30. Design intensity for heavy ion beam
GSI SIS18 (world record intensity of U : 3.2 x 1010 ppp)
20 injection turns
40% beam loss at Septum magnet during injection
limitation of ring optics
J-PARC Booster (design intensity of U :15~ 30 x 1010 ppp)
> 500 injection turns
lower beam loss at injection
flexible ring optics

31. Requirements of Accelerator in J-PARC
No confliction with other proton programs (MLF/NU)
Reduction of space and budget (by using RCS and MR)
Variable ion species (p, Li, C, Si, Ar, Cu, Xe, Au, U etc.)
Variable beam energy (1 – 19 GeV/u for U)
High beam rate (1011 per cycle)
This design work satisfies all requirements!

32. Total cost of accelerator part : 120 M$
Design task
Optimization of ring optics and injection scheme
Accelerating simulation of HI beam with multi charge state
Multi particles simulation with space charge force
Magnet design and cost estimation
HI LINAC design and cost estimation
Writing accelerator part of “Technical Design Report(TDR)”
Proposal to Accelerator Technical Advisory Committee(A-TAC)
Total cost of accelerator part : 120 M$

33. Summary
The existing facilities in J-PARC has possibility for high intensity beam and highest efficiency of slow extraction.
The proposed HI accelerator scheme has no conflict with existing programs.
In the RCS, more than 1011 U86+ ions can be achieved without any significant beam losses.
HI beam accumulation for high intensity is very challenging.
Innovative injection scheme for high-intensity HI beam is under design work.
HI program goes forward as future project in J-PARC.