Rare-RI Ring (R3)

Overview Concept Configuration Technical Information Publication list/Link


The injection line consists of ten quadrupoles and one dipole, in addition to two septa for injecting the particles. The ring consists of six magnetic sectors, each consisting of four dipoles. This dipole is a rectangular magnet with a radially homogeneous magnetic field. Ten one-turn trim-coils are installed in the two outer dipoles of each magnetic sector. The kicker magnets are located in the position of the phase advance 3π/2 from the injection septa, and the extraction septa are located in the position of the phase advance 3π/2 from the kicker magnets.
Plastic scintillation counters are installed in each straight section to check the injection trajectory. Carbon-foil + MCP detector and resonant Schottky pick-up are used to get a revolution frequency information from a circulating particle with and without destruction.

TOF start/stop detectors can be installed at just before/after the ring, respectively. ΔE-E detectors for particle identification can also be installed in a chamber after extraction.

Ten Quadrupoles and one dipole of the injection line

Quadrupole   Dipole
Type : laminated Type : laminated
Bohr radius : 50 mm  GAP : 80 mm
Length : 600 mm Radius of curvature : 4.045 m
Max. current : 1000 A Max. current : 3000 A
Coil / pole : 12 turns Coil / pole : 20 turns
Max. field* : 0.6 Tesla Max. field : 1.7 Tesla
  Bending angle : 15.7 degrees**

* It corresponds to the pole-tip magnetic field.
** Bending angle can be adjusted by the bump coil.

Septum magnets

  Septum 1 Septum 2
Type :  Lumped Lumped
Gap : 45 mm 45 mm
Radius of curv. : 5.05 m 13.0 m
Max. current : 2200 A 2200 A
Coil : 20 turns 8 turns
Bending angle : 12.7 degrees 5.3 degrees
Max. rigidity : 6.0 Tm 6.0 Tm

Extraction part also has two septa.
The specifications are same as injection part.

Specifications of the ring

Circumference :   60.35 m
Length of straight section :    4.02 m
Momentum acceptance* :   1 %
Max. injection energy :   170 MeV/u
* It corresponds to the isochronous adjustable range.
Possible momentum width of extraction is about 0.5 %.
For a beam energy of 170 MeV/u
Revolution frequency :    2.65 MHz
Transition γtr :    1.18
Betatron tune :   Qx 1.18 , Qy 0.93
Max. Beta function :    βx 8.4 m , βy 11.9 m
Dispersion of straight section :    7.0 m


Type : Copper hollow conductor
Size : 6 mm x 6 mm  Φ3 mm
Right hand of figure shows the average magnetic field generated by each trim-coil excited at 300 A.

Fast-kicker system

Block diagram of fast-kicker system

Characteristic impedance : 12.5 Ω
Thyratron switch :  CX1171 made by e2v
Max. charging voltage : 75 kV
Max. repetition for injection : 100 Hz
Interval between injection and extraction :

Minimum :

700 μs

Maximum :

9.5 ms
  (adjustable in 10 ns step.)
Type of kicker magnets :  Distributed constant twin type
Specifications of the kicker magnet

Capacitance of cell : 350 pF
Inductance of cell : 100 nH
※ Additional capacitances are used for impedance matching.

Resonant Schottky pick-up

Cavity* : Pillbox shape
Outer diameter :  700 mm
Inner diameter : 320 mm
Length : 200 mm
Resonant frequency fres :  173 MHz
Tuning range : ±1.5 MHz
Quality factor Q0 :  1880
Shunt impedance Rsh : 170 kΩ
* Cavity is filled with air and electrically isolated from the beam tube by a ceramic insulator.

 This system was able to aquire the revolution frequency information from one particle of Kr.

Information of the detectors

1.Timing detector for circulating particles

- Carbon foil + MCP*

Thickness of C-foil :  60 μg/cm2
Size of C-foil : 100 mm x 50 mm

* For details, please see Ref. [4].

2. TOF start/stop detectors

 A T-shaped plastic scintillation counter is used for TOF start detector. For TOF stop detector, a standard plastic scintillation counter is used. For the TOF measurement, these detectors can be used or they can be replaced by the user's detectors depending on the requirements of the experiment.

3. Detectors for particle identification.

 An ion chamber or Si detector will be used for ΔE measurement. Such as NaI can be used for total-E measurement.

Vaccum system

For the rough pumping
Turbo Pump* : 250 L/s for N2
*It is a movable type with a scroll pump
For the ultra-high vaccum condition*
Ion Pump :  500 L/s for N2
NEG pump : 2000 L/s for H2.

*The combination of the ion and NEG pumps for the ring is 26 units.


Photo of the control system
Pressure (Goal) : 10-8 Pa with baking



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