Experiments using a recoil-producing
nuclear separator

Advanced Science Research Center, Japan Atomic Energy Agency
Research Fellow Katsuhisa Nishio1

Recoil-producing nuclear separator（JAEA Recoil Mass Separator）
Separation of produced nuclei
Detect nuclei produced Detect

Targetθ = 0°

BeamRevolution
θ
BeamTarget nucleusn

θ = 40°nThe nuclei produced in the fusion
reaction recoil and fly out in thesame direction as the beam (setRMS in the zero-degree direction).

2

Reactions learned in practiceTandem acceleration【 Beam energy
160MeV】

Compound nucleusnResidual nucleusnn
34S + 169Tm = 203At
851669α Collapsennn
199Atnn

Compoundnucleus

3Beam energy and evaporated residual nuclei produced

34S34S

The excitation energy increases
in proportion to the kinetic
203At（Compound nucleus） energy of 34S.

169Tm
238U272Hs【 Beam energy146MeV】【 Beam energy【 Transuranium element 268Hs】
Compound nucleus
Compound nucleus 160MeV】
Compound nucleus
n0.5

203At

0.5
Nuclear fission

0.5
202At

0.50.5nNuclear fission

0.50.5n203At202At

n201AtNuclear fission
0.50.5

Nuclear fission
0.5

200At

Nuclear fission

Residual nucleus(0.5) 3 = 0.125

0.9990.001
nn0.5
201At

Nuclear fission

n272HsNuclear fission

271Hs

0.999

n

Nuclear fission

0.50.001

n270Hs

0.001

0.999

n200At0.5

0.5

Nuclear fission

199At

Nuclear fission

Residual nucleus(0.5) 4 = 0.0625

269Hs

0.999

n0.001
268Hs

Nuclear fission

Residual nucleus(0.001) 4 = 1x10-124

Generation cross section of astatine evaporation residualnuclei
Energy in laboratory
systems（MeV）
ELAB (MeV)

103

169Tm

Solid line

102

Nuclear
Fusion fusion

101

Nuclear fission
Fission100

CrossCross
section (mb)sectionalarea

34S（ Calculations incorporating nuclear
deformation The calculation
incorporates the deformationof the nucleus, correct image ）135 140 145 150 155 160 165 170 175 180

199

At(4n)

200

At(3n)

10-1

10-2

Evaporation
Residual
nucleusResidue

34S

169Tm

At(5n) Dotted line

198

（ Calculations that do not incorporate
nuclear deformation Calculations that
do not incorporate ）201

At(2n)

10-3110 115 120 125 130 135 140 145 150

Ec.m.
Collision energyat (MeV)
the center of gravity system（MeV）
5

Velocity Filter (Velocity Selector)
Force applied by an electric field Force applied by magnetic field

FE = q E

FB = q v x B

Apply a magnetic field so that it intersects the electric field,
also make the forces work in opposite directions.

FE = q E
FB = q v B+q（FE = FB）

Both forces are balanced to move straight ahead.

E=v
B

Through an evaporation residue (residue) or through a beam (beam), respectively.

Eresidue
Bresidue= vresidue

Ebeam
Bbeam= vbeam

vresidue = vbeam So the two can be separated.

vresidue (199At) = 0.50 cm/ns
vbeam (34S) = 3.01 cm/ns
6

Ion's resistance to bending in magnetic field B andelectric field E（Bρ and Eρ）
Bρ and Eρ are ion (mass number A, kinetic energy ε, charge + q)
specific values, the resistance to bending in magnetic and electric fields, respectively.

Ρ(Radius ofcurvature)Bρ ∝Eρ ∝0.5

34

Probability

S (Beam,160MeV)

0.4

199

At
(Residue,26.2MeV)

0.3

169

Tm
(Recoi,89.2MeV)

0.2
0.1
5

10

1520

25

Ion valence

3035

S-34
(15+, 160MeV)
At-199(17+, 26.2MeV)
Tm-169(26+, 89.2MeV)＋E(Electric field strength)

B (Magnetic field strength)

0.6

0.0

√ A・εqρ（Radius of ―curvature） ――2ε＋q＋Bρ (Tm)Eρ (MV)Eρ/Bρ（Any）

0.7088

21.33

30.09

0.61103.08

5.04

0.6800

6.86

10.09
7

Recoil-producing nuclear separator （JAEA－RMS）
199At

Carbon Foil

34S

34S

199At
Faraday Cup

169Tm

Q1,2

Electricfield

Acceptance of kinetic energy＝±１２％ of set value
Acceptance of mass number＝±４％ of set value

MagneticfieldElectricfieldSi strip
detector

Q3,4
MCPDetectors

Silicon detector
Timing detector

Residualnucleus

8Target scattering tank（e.g. 169Tm thin film target）
RMS entrance
199..At34S

Elastic scattering

34S

Charge reset
Foil (film of carbon)
Equilibrate charge
distribution
Measure Elastic Scattering
Silicon detector
Evaporation residual nucleus
cross section Necessary todetermine

Make the beam glow
169Tm thin film target
9Setting up the electric and magnetic fields for RMS

Determine the mass number A, kinetic energy E, and charge +q of theevaporating residual nucleus
E’beam = 159.3 MeV(After passing through carbon thin film)

YieldCarbon Film
54 μg/㎝2

E’’beam =158.8MeV(Tm target center)
169Tm

162 μg/㎝2

Ebeam = 160.0 MeV(34S)Charge + ｑ
Charge Reset
Foil(Carbon film)

Eresidue = 26.2 MeV
4n neutrons evaporated
Energy of evaporationof 4n neutrons199At（Tm target center)
199
Composite nucleus
E’kinetic energy

×203

E’’residue = 23.6 MeV
Energy after passing
through carbon film

199

16+At85√ A・EBρ∝qresidue = 25.5 MeV

Energy after passing through half
the thickness of the Tm targetΕρ∝2Eq 10α崩壊を観測する検出器
シリコン（Si）ストリップ検出器…

Siストリップ検出器

16本のストリップe-

16本のストリップからそれぞれ信号を出す。

Si断面図
Eα

③ α崩壊の観測（寿命τののち）~60％が全エネルギー吸収②インプラント

MCP検出器
Siストリップ検出器

①②MCP
検出器

e-蒸発
残留核

RMS

αソース
（241Am）
薄膜
0.5μmマイラー箔
金50μg/㎝2 を蒸着① 199At 飛んでくるe- eτ ~9.9 秒

MCP検出器③時間
時間

11Energy spectrum of alpha ray (example ofmeasurement)

Numberof events
イベント数

500

130

82

Kr +Te207,208

Ra204

Rn250

208

Fr

206,207Fr

206,205

Rn207
Rn

209

Ra205

At0246810Alpha Particle Energy
α粒子のエネルギー/ MeV

1212

Digital data processing

1GHzIN

500MHz 100MHz for Si x 3 modules
INININ

MCP
制御室で見る
オシロスコープ

Si strip Si strip
No.1~6 No.7~12OUT

OUT

Si stripNo.13~16
Elastic scattering
Monitor
Si PIN diode

OUT

Waveform monitor output(Viewed by control room diziplay viaoscilloscope)13

Evaporation process may emit protons.
34S

Collision energy inlaboratory(MeV) system（MeV）
ELAB

169Tm

103

CrossCross section (mb)sectionalarea

102

Compound nucleus

10p

203At

10n202Po

Nuclear fission

Nuclear fission

200PoFissionResidual nucleus
Evaporation
Residue

1200

At(3n)

010-2

Nuclear fission

Fusion

nt

199Po

199

At(4n)

199

Po(p3n)

10-1n

201Po

135 140 145 150 155 160 165 170 175 180

198

At(5n)

198

Po(p4n)200

Po(p2n)

201

At(2n)

10-3
110 115 120 125 130 135 140 145 150

Collision energy at the center
gravity system（MeV）
Ec.m.of(MeV)

Nuclear fission
Residual nucleus
14