Overview Concept Configuration Technical Information Publication list/Link


BigRIPS Configuration


The BigRIPS separator has been designed to be a two-stage RI beam separator. The first stage from the production target to the F2 focus comprises a two-bend achromatic spectrometer, consisting of four superconducting quadrupole triplets (STQ) (STQ1 to STQ4) and two room-temperature dipoles (RTD) with a bending angle of 30 degrees (D1 and D2). This first stage serves to produce and separate RI beams. The in-flight fission of uranium beams as well as the projectile fragmentation of various heavy ion beams are employed as production reactions. An achromatic wedge-shaped degrader is inserted at the momentum-dispersive focus F1 at an intermediate point to make isotopic separation based on the technique called momentum achromat. A high-power beam dump is placed inside of the gap of the first dipole D1 to stop primary heavy ion beams. The first stage is surrounded by thick concrete blocks of about 10,000 tons to shield neutron radiation from the target and beam dump. A telescopic system consisting of two STQs (STQ5 and STQ6) follows the achromatic focus F2, transporting separated RI beams to the second stage. The second stage from the F3 focus to the F7 focus consists of eight STQs (STQ7 to STQ14) and four RTDs with a bending angle of 30 degrees (D3 to D6), comprising a four-bend achromatic spectrometer. The intermediate focuses F4, F5 and F6 are momentum-dispersive, while the final focus F7 is doubly achromatic.
Since our energy domain is not so high, the purity of RI beams is expected to be poor due to the nature of energy loss as well as the mixture of charge state. Several isotopes are mixed in an RI beam. To overcome this difficulty, the second stage of BigRIPS separator is employed to identify RI-beam species. Position-sensitive detectors, timing detectors and δ E detectors are placed at the focuses of the second stage to measure the Bρ value, the time-of-flight and the energy loss of RI beams. The scheme allows one to determine the atomic number (Z), the ratio of mass number to charge number (A/q) and the momentum (P) in an event-by-event mode, making it possible to deliver tagged RI beams to experimental setups placed downstream of the BigRIPS separator. RI-beam experiments, particularly those of secondary reaction studies, are significantly facilitated by the delivery of tagged RI beams. The angular acceptances of the BigRIPS separator have been designed to be 80 mr horizontally and 100 mr vertically, while the momentum acceptance will be 6 %. The maximum bending power is 9 Tm. The total length is 77 m.
The angular and momentum spreads of fission fragments at 350 MeV/nucleon are estimated to be about 100 mr and 10 %, respectively, when symmetric fission is assumed. The acceptances of BigRIPS are comparable to those values, allowing one to achieve high collection efficiency for the in-flight fission: almost half of the produced fission fragments can be accepted for some isotopes. These high acceptances are made possible by the use of superconducting quadrupoles with large apertures and room-temperature dipoles with large gaps.

BigRIPS seperator


Type Seperate sector
Separator config. Tandem
The first stage TQ-D-TQ-TQ-D-TQ
The second stage TQ-D-TQ-TQ-D-TQ-TQ-D-TQ-TQ-D-TQ
Degrader type Wedge, @F1, F5, F4, F6
Magnet type Dipole : Normal conducting
Quadrupole : Super conducting
Angular acceptance Horizontal : 80 [mrad]
Vertical : 100 [mrad]
Momentum acceptance 6 [%]
Maximum rigidity 9 [Tm]
Total path length 77 [m] (F0-F7)
Momentum Dispersion
First stage : -2.31 [cm/%]
Second stage : 3.3 [cm/%]
Momentum Resolution
First stage : 1290
Second stage : 3300
Focal plane
F1 : momentum dispersive
F2,F3 : achromatic
F4,F5,F6 : momentum dispersive
F7 : doubly achromatic


ZeroDegree Configuration


ZeroDegree Spectrometer

Magnet configuration TQ-D-TQ-TQ-TQ-TQ-D-TQ
Total path length(F8-F11) 36 [m]
Achromatic: Large acceptance mode
Momentum accptance 6 [%]
Maximum rigidity 7.3 [Tm]
Angular acceptance Horizontal : 90 [mrad]
Vertical : 60 [mrad]
Momentum dispersion 2.24 [cm/%]
Momentum resolution 1240
Achromatic: High resolution mode
Angular acceptance Horizontal : 40 [mrad]
Vertical : 60 [mrad]
Momentum accptance 6 [%]
Maximum rigidity 9.0 [Tm]
Momentum dispersion 2.12 [cm/%]
Momentum resolution 2120
Dispersive spectrometer mode
Angular acceptance Horizontal : 40 [mrad]
Vertical : 60 [mrad]
Momentum accptance 4 [%]
Maximum rigidity 9.0 [Tm]
Momentum dispersion 4.13 [cm/%]
Momentum resolution 4130


Beam line devices

Production Target

Target type Rotating target, water cooling
Target material Be, or in preparation
Heat load 22 [kW] for beam size of 1mm φ
System weight 3.6 [t]


Now in preparation: Please request the shape and thickness

Beam line detector

F1 Slit(H), Strip slit, Degrader, Beam Stopper, PPAC
F2 Slit(V), Slit(H), Beam Stopper, Target, PPAC, Ion C., Plastic, Si
F3 Target, PPAC, Ion C., Plastic, Si
F4, F6 Degrader, Slit(H), PPAC
F5 Slit(H), Degrader, PPAC, Plastic
F7 Slit(V), Slit(H), Target, PPAC, Plastic, Ion C.,Si
F8,F11,F12 PPAC, Slit(V), Plastic, PPAC
F9,F10 Degrader, Slit(H), PPAC, Plastic, PPAC, Charge Stripper


Magnet property

Dipole Magnet

Bending angle 30 [degree]
Yoke shape H type
Radius of central trajectory 6 [m]
Maximum magnetic field 1.6 [T]
Pole gap 14 [cm]
Path Length 3140 [mm]
Effective width +-120 [mm]
Maximum current 1100 [A]
Current density 5.6 [A/mm2]
Number of turns/coil 100 [turn/Coil]
Weight 62 [t]

Quadrupole Magnet

Specification Stored energy [MJ] Inductance [H]
Air core type
Q1 Q2 Q3 Q1 Q2 Q3
0.36 1.26 0.85 1.33 6.47 4.35
Super ferric type
Q500 Q800 Q1000 Q500 Q800 Q1000
0.13 0.19 0.13 9.3-16 14.7-26 14.7-26

Name Bore radius [mm]
(room temp.)
Effective length [mm]
Maximum field gradient [T/m]
  Q1 Q2 Q3 Q1 Q2 Q3
STQ1 120 (90 for Q1) 500 800 500 24 20 20
STQ2-4 120 500 800 500 14.1 14.1 14.1
STQ5-6,STQ10-11 120 500 1000 500 14.1 14.1 14.1
STQ7-9, STQ12-14 120 500 800 500 14.1 14.1 14.1


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