Cooler Storage Ring at China Institute of Modern Physics

Abstract

CSR, a new ion cooler-storage-ring project in China IMP, is a double ring system, and consists of a main ring (CSRm) and an experimental ring (CSRe). The two existing cyclotrons SFC (K=69) and SSC (K=450) of the Heavy Ion Research Facility in Lanzhou (HIRFL) will be used as its injector system. The heavy ion beams with the energy range of 7--30 MeV/nucleus from the HIRFL will be accumulated, cooled and accelerated to the higher energy range of 100--500 MeV/nucleus in CSRm, and then extracted fast to produce radioactive ion beams or highly charged heavy ions. Those secondary beams will be accepted and stored or decelerated by CSRe for many internal-target experiments or high precision spectroscopy with beam cooling. On the other hand, the beams with the energy range of 100--1000MeV/nucleus will also be extracted from CSRm by using slow extraction or fast extraction for many external-target experiments. CSR project was started in the end of 1999 and will be finished in 2006. In this paper the outline and the activities of the project will be described.

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COOLER STORAGE RING AT CHINA INSTITUTE OF MODERN
PHYSICS*
J.W. Xia#, W.L. Zhan，B.W.Wei and CSR group
Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS)
P.O. Box 31, Lanzhou, 730000, P.R. China
Abstract
CSR, a new ion cooler-storage-ring project in China
IMP, is a double ring system, and consists of a main ring
(CSRm) and an experimental ring (CSRe). The two
existing cyclotrons SFC (K=69) and SSC (K=450) of the
Heavy Ion Research Facility in Lanzhou (HIRFL) will be
used as its injector system. The heavy ion beams with the
energy range of 7--30 MeV/nucleus from the HIRFL will
be accumulated, cooled and accelerated to the higher
energy range of 100--500 MeV/nucleus in CSRm, and
then extracted fast to produce radioactive ion beams or
highly charged heavy ions. Those secondary beams will
be accepted and stored or decelerated by CSRe for many
internal-target experiments
spectroscopy with beam cooling. On the other hand, the
beams with the energy range of 100--1000MeV/nucleus
will also be extracted from CSRm by using slow
extraction or fast extraction for many external-target
experiments. CSR project was started in the end of 1999
and will be finished in 2006. In this paper the outline and
the activities of the project will be described.
or high precision
INTRODUCTION
Since the end of 1999, a new Cooler Storage Ring
(CSR) project [1] has been started to upgrade the Heavy
Ion Research Facility in Lanzhou (HIRFL) [2], shown in
Fig. 1. CSR will provide Radioactive Ion Beams (RIBs)
and high-Z heavy ion beams for nuclear physics and
atomic physics. The existing HIRFL complex, consisted
by a main accelerator SSC (Separated Sector Cyclotron,
K=450) and a pre-accelerator SFC (Sector-Focusing
Cyclotron, K=69), will be used as the injector system of
CSR. The light heavy ions, example C, N, O etc., can be
injected into CSRm directly from SFC, but those heavy
ions (A>40) should be accelerated by the combination of
SFC and SSC before the injection. The mean extraction
radius of SFC and SSC are 0.75m and 3.20m
respectively.
GENERAL DESCRIPTIONS
Outline
CSR is a multipurpose Cooler Storage Ring system
that consists of a main ring (CSRm), an experimental
ring (CSRe), and a radioactive beam line (RIBLL2) to
connect the two rings, shown in Fig.1. The heavy ion
beams with the energy range of 7~30 MeV/µ from the
HIRFL will be accumulated, cooled and accelerated to
the high-energy range of 100~500 MeV/µ in the main
ring, and then extracted fast to produce radioactive ion
beams (RIBs) or highly charged heavy ions (high-Z
beams). Those secondary beams will be accepted and
stored or decelerated by the experimental ring for many
internal-target experiments
spectroscopy with beam cooling. On the other hand, the
beams with the energy range of 100~1000MeV/µ will
also be extracted from CSRm by using slow extraction or
fast extraction for many external-target experiments, and
for the future development, the possibility of internal-
target mode in CSRm was reserved for those high-energy
proton experiments with the energy range of 2~2.8GeV.
Two electron coolers located in the long straight
sections of CSRm and CSRe, respectively, will be used
for beam accumulation and cooling.
The beam parameters and the major machine
parameters of CSR are listed in table 1.
or high precision
SFC
TR 5
TR 3
TR 4
TR 2
TR 1
TL2
TL1
SSC
PD C
T1
R I BLL1
R I BLL2
PT

Figure 1: Overall layout of HIRFL-CSR.
Normal Operation Mode
CSR is a double ring system. In every operation cycle,
the stable-nucleus beams from the injectors are
___________________________________________
*Work supported by the center government of China
#xiajw@impcas.ac.cn
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2710-7803-8859-3/05/$20.00 c ?2005 IEEE

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Table 1 Major parameters of the CSR
CSRm
161.00
Stable nuclei: p -- U, RIBs: A<238

Circumference (m)
Ion species
CSRe
128.80
Stable nuclei: p -- U,
RIBs :A<238
2000(p), 750 (C6+), 500 (U90+)
103--9 (stable nuclei, RIBs)
9.40
1.6
0.1--0.2
Max. energy (MeV/µ)
Intensity (Particles)
Bρmax (Tm)
Bmax (T)
Ramping rate (T/s)
Repeating circle (s)
2800(p), 1100 (C6+), 500 (U72+)
105---109 (stable nuclei)
12.05
1.6
0.1--0.4
～ 17 (～10s for accumulation )
Fast extraction mode
200 (∆P/P = ±0.15 %)
40
1.4 (εh= 50 π mm-mrad)

7---50
4.0
Acceleration Accumulation
1, 2 16, 32, 64
0.24 / 1.81 6.0 / 14.0
1 × 7.0 1 × 20.0
3.0 × 10-11
Acceptance
A h (π mm-mrad)
A v (π mm-mrad)
∆P/P (%)
E-cooler
Ion energy (MeV/µ)
Length (m)
RF system
Harmonic number
fmin/fmax (MHz)
Voltages (n × kV)
Vacuum pressure (mbar)
Normal mode
150 (∆P/P =±0.5%)
75
2.6 (εh= 10 π mm-mrad)
10---500
4.0
Capture
1, 2
0.4 / 2.0
2 × 10.0
3.0 × 10-11

accumulated, cooled and accelerated in the main ring
(CSRm), then extracted fast to produce RIBs or highly
charged ions. The experimental ring (CSRe) can obtain
the secondary beams once for every operation cycle. The
accumulation duration of CSRm is about 10s.
Considering the ramping rate of magnetic field in the
dipole magnets to be 0.1~0.4 T/s, the acceleration time of
CSRm will be nearly 3s. Thus, the operation cycle is
about 17s.
In CSRe, two operation modes will be adopted. One is
the storage mode used for internal-target experiments or
high precision spectroscopy with electron cooling.
Another one is the deceleration-storage mode used for
atomic-physics experiments. Fig. 2 shows the magnetic
field exciting procedure of the two rings.


Figure 2: Magnetic field exciting procedure of CSR.
Beam Accumulation
Three modes will be used in CSRm to accumulate ions
up to 106~9 in a short duration of 10s. The first is the
Stripping Injection (STI) for those light heavy ions
(A<24). The second is the Multiple Multi-turn Injection
(MMI) in the horizontal phase space with the acceptance
of 150π mm mrad. The third one is the combination of
the horizontal MMI and the RF Stacking [3] (RFS) in the
momentum phase space. In the third one the horizontal
acceptance is 50π mm mrad used for the multi-turn
injection and the momentum acceptance is 1.25% for the
RF stacking. During the accumulation, electron cooling
will be used for the cooling of beam in order to increase
the accumulation ratio and efficiency. Table 2 is the
accumulation parameters for several typical ions.
Table 2 Parameters of the beam accumulation in CSRm

C4+
Injector SFC
Energy (MeV/µ) 7
Current (pµA) 2
Current (pps)
1.2×1013 3×1012 6×1010 6×109
Particles/Turn
5×107
Efficiency of str. 68%
Method STI
Injection pulse (ms) 1--5
Cycle (ms) 2500
Period (s) 3
Gain factor of MMI 30
Particles
1.5×109 2×109 5×106
O7+
SFC
10
0.5
Xe48+
SSC
20
0.01
U72+
SSC
10
0.01
1×107 1.5×1052×104
19%
RFS MMI
0.1 0.1
100 250
10 10
2.8 5
15%
MMI
0.1
100
10
5
1×106
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STORAGE RING LATTICE
CSRm Lattice
CSRm is a racetrack shape, as shown in Fig. 3, and
consists of four arc sections. Each arc section consists of
four dipoles, two triplets and one doublet. The lattice of
each arc section is given as follows,
----- L1-----FDF--B--B--F---- L2---DF--B--B—F (1/2D)
Where, 2L1 is a long-straight section with dispersion free
for e-cooler or extraction kicker and internal target. L2 is
a dispersion drift for beam injection, extraction and RF
cavity. Fig. 4 is the distributions of the β-functions and
the dispersion for this lattice, and Table 3 is the lattice
parameters of CSRm.

Figure 3: Lattice layout of CSRm.

0 20 40 60 80100120140160
0
5
10
15
20
25
30
35
40
βx βy Dx
CSRm TWISS functions(m)
L(m)




Figure 4: β and dispersion of CSRm
CSRe Lattice
The layout of CSRe is shown in Fig. 5. It has a race
track shape and consists of two quasi-symmetric parts.
One is the internal-target part and another is the e-cooler
part. Each part is a symmetric system and consists of two
identical arc sections. Each arc section consists of four
dipoles, two triplets or one triplet and one doublet. 11
independent variables for quadruple are used in CSRe.
The lattice of the half ring is given as follows,
--LT--FD-F--B-B--LR--FD-F-B-B--B-B-F-DF--LR--B-B--FD--Lc--
Where, 2LT and 2LC are the long-straight sections with
dispersion free for internal target and e-cooler. LR is the
dispersion drift for RF cavities. Table 3 shows the lattice
parameters of CSRe, and Fig. 6 denotes the distributions
of the β-functions and the dispersions for the lattice.

Figure 5: Lattice layout of CSRe.


Figure 6: Tiwiss functions of CSRe.
Table 3 Lattice parameters of CSRm and CSRe

CSRm CSRe
Transition gamma γtr = 5.418
γtr = 2.629
Tune values
Chromaticity
Qx / Qy = 3.64 / 2.61
Q’
Qx / Qy = 2.53 / 2.57
x / Q’
x / Q’
y = -3.17 / -5.37 Q’
y = -3.10 / -3.74
Max. β (m)
βx/βy =12.1/13.5 (B)
βx/βy =15.3/30.5 (Q)
Dmax(x)=3.1(B, βx=9.0)
Dmax(x)=5.4(Q , βx=9.9)
βx= 8.0 , Dx = 4.1 (SM)
βx= 9.7, Dx =3.9 (Q)
βx/βy=10.0/16.7, Dx =0 βx/βy=12.5/16.0, Dx = 0
βx/βy=10.0/16.0, Dx =0 βx/βy=5.4/1.5, Dx=0
βx/βy=8.0/22.5, Dx=4.0 βx/βy=4.0/8.4, Dx=4.0
βx/βy =17.6/8.2 (B)
βx/βy =30.9/22.3 (Q)
Dmax(x)=6.5(B, βx=13.0)
Dmax(x)=7.8(Q, βx=16.0)
βx=30.4 , Dx = 0 (SM)
βx=30.9, Dx = 0 (Q)
Dispersion (m)
Injection (m)
E-cooler (m)
Target (m)
RF station (m)
MAJOR SUBSYSTEM
Magnets and Correlative Sub-systems
All magnet cores of CSR will be laminated of 0.5mm-
thick sheets of electro-technical steel with high induction
and cold-rolled isotropy. Coils will be made of T2 copper
conductor with hollow and insulated with polyimide
stick tape and vacuum epoxy resin impregnating. In
order to reach the necessary field uniformity at the
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Page 4

different levels of the range of 1000Gs ~ 16000Gs, a so-
called modified H-type dipole was designed for CSRm.
In CSRe the C-type dipole with large useful aperture will
be adopt for physics experiments.
All power supplies of the ring magnets need DC and
pulse operation modes, and high current stability, low
current ripple and good dynamic characteristic were
required. Two types of supply, traditional multi-phase
thyristor rectifier for dipoles and switching mode
converter for quadruples, were adopted. Table 4 is the
major parameters of magnets and its correlative power
supplies and vacuum chambers.
Table 4 Major correlative parameters of the magnets

Dipole
Number×angle (deg.)
Bending radius (m)
Field range (T)
Ramping rate (T/s)
Air gap (mm)
Useful aperture (mm2)
Homogeneity (∆B/B)
±1.5×10-4
Vacuum. Chamber
Inner aperture (mm2)
Cross section Rectangular Rectangular
Supply of dipole
Number
Feeding mode
Stability (at low cur.) ±1×10-4/8h
Ripple (at low cur.)
Tracking precision
Quadruple
Number
Gradient range (T/m) 0.3—10.0
Bore diameter (mm)
Useful aperture (mm2)
∆K/K
±1.5×10-3
Ideal length (m)
Vacuum. Chamber
Aperture (mm2)
Cross section Octagonal
Supply of quadruple
Number
Feeding mode Independent Independent
Stability (at low cur.) ±1×10-4/8h
Ripple (at low cur.)
Tracking precision
CSRm CSRe

16×22.5
7.6
0.1--1.4
0.1--0.4
80
140×60
16×22.5
6.0
0.1--1.4
0.1--0.4
84
220×70
±1.5×10-4

156×61 236×70

1 1
Series Series
±1×10-4/8h
5×10-5
±3×10-4
5×10-5
±3×10-4

30 22
0.3—6.5
240
280×140
±1.5×10-3
0.65, 0.75
170
160×100
0.5, 0.65

180×110 285×150
Octagonal

30 22
±1×10-4/8h
5×10-5
±5×10-4
5×10-5
±5×10-4
Electron-cooler System
Two electron coolers will be equipped in CSRm and
CSRe respectively for heavy ion beam cooling. In CSRm
the E-cooling will be used for the beam accumulation at
the injection energy range of 7~30 MeV/μ to increase the
beam intensity. In CSRe the e-cooling will be used to
compensate the growth of beam emittance during
internal target experiments or provide high quality beams
for the high resolution mass measurements of nuclei.
Table 5 is the major parameters of the two e-coolers, and
Fig. 7, Fig.8 are the general view of them. The two
coolers are almost same with the only difference of the
high voltage unit in order to reduce the time of
development and the production cost of the devices.
Table 5 Major parameters of the two e-coolers
Parameters
Ion Energy [MeV/u]
Electron Energy [keV]
Electron beam current [A]
Cathode radius [cm]
Magnetic expansion factor
Max. field of gun [kG]
Field of collector [kG]
Field of cooling section [kG] 0.6-1.5
Length of cooling section [m] 4.0 (Leff.= 3.4m)
Installation length [m]
Bending angle of toroid
CSRm
7-50
4-35
3 (1.0A@5.5keV)
1.25
1- 4
2.4
1.2
CSRe
10-500
5-300
1.25
1- 10
5
1.2
0.5-1.5
7.2
90°
7.2
90°
1.0 bending radius of toroid [m] 1.0

1. E-gun, 2. Solenoid of gun, 3. Toroid, 4. Main solenoid,
5. Electrostatic deflector, 6. Solenoid of collector,
7. Collector, 8. Dipole corrector.
Figure 7: Layout of the CSRm e-cooler.

1. E-gun, 2. Accelerating tube, 3. Solenoid of gun,
4. Toroid, 5. Main solenoid, 6. Electrostatic deflector,
7. Solenoid of collector, 8. Decelerating tube, 9.
Collector, 10. 300KV-HV System, 11. Dipole corrector.
Figure 8: Layout of the CSRe e-cooler.
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MAGNET TEST RESULTS OF CSRm
Results of CSRm Dipole Field
The dipole field of CSRm was measured in the range
of 500Gs to 1.65T with the exciting current from 76A to
3000A. It is larger than the used range of 0.1T to 1.6T.
According to the measurement, the homogeneity of field
is less than 4×10-4 in the required good-field width of
140mm, the multiple components error are less than
8×10-4 , and the dipole-field reproducibility is less than
3×10-4 between 16 dipoles and reference dipole. Fig. 9 is
the dipole integral-field distribution versus the radius at
the field level of 1000Gs. Fig. 10 is the multiple
component errors versus the whole exciting current.
Fig.11 is the reproducibility of CSRm dipoles at the
1000Gs level.

Figure 9: Dipole field distribution versus the radius.
0 5001000150020002500
I (A)
30003500
-0.0014
-0.0012
-0.0010
-0.0008
-0.0006
-0.0004
-0.0002
0.0000
0.0002
0.0004
0.0006
0.0008
0.0010
0.0012
0.0014
∆Βi/B
4
6
8
10
12

Figure 10: Multiple component errors in CSRm dipole.

Figure 11: Reproducibility of CSRm dipole.
Results of Quadruple Field
The maximum quadruple gradient of CSRm is reached
to 10 T/m with the exciting current of 690A, and the
multiple components error are less than 5×10-4. Fig. 12 is
the multiple-component errors versus the whole exciting
current from 15A to 700A.

Figure 12: Multiple component errors of quadruple.
PROJECT STATUS
In the summer of 2001 the building construction was
over, and in the beginning of 2004 the major fabrication
and installation for CSRm and the injection line from
HIRFL were finished. Up to the spring of 2005, the
fabrication and installation of CSRe and those beam lines
between the two storage rings will be completed.
Since 2003 many offline tests have been done. For
example, e-cooler, RF station, power supply, Ultra-high
vacuum, magnetic field measurement, etc. For the e-
cooler, the hollow electron beam can be obtained to
partially solve the problems due to space charge effect
and reduce the effect of recombination between the ions
and the e-beam. In CSRm the vacuum pressure already
reached to 5×10-12 mbar.
Several subsystems will be delayed, for example,
control and diagnosis systems, injection bumps and fast
extraction kicker.
At February 3 of 2005, the first-turn of CSRm was
obtained without any adjusting. 2005 is the first
commissioning time for CSRm, and in the end of 2006
the whole fist commissioning of CSR will be finished.
REFERENCES
[1] J. W. Xia, et al., HIRFL-CSR Plan, Proc. of the 6th
China-Japan Joint Symposium on Accelerators for
Nuclear Science and Their App., Chengdu, China,
Oct. 1996, 24pp.
[2] B. W. Wei, Results From Lanzhou K450 Heavy Ion
Cyclotron, Proc. of 1989 Particle Acc. Conf., IEEE.
[3] Y J. Yuan et al., Simulation of RF Stacking and
Multiple Single-Turn Injection and Multi-turn
Injection, Proc. of the 14th Inter. Conf. on
Cyclotrons and Their App., South Africa, 1995,
479pp.
Proceedings of 2005 Particle Accelerator Conference, Knoxville, Tennessee
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