Fission Study using Multi-nucleon Transfer Reactions

( Surrogate Reactions )

重イオン多核子移行反応による核分裂特性の研究（代理反応）

Katsuhisa Nishio

Advanced Science Research Center

Japan Atomic Energy Agency

西尾 勝久

日本原子力研究開発機構

先端基礎研究センター

ND2018, 29-30 Nov., Tokyo Institute of Technology1

Japan Atomic Energy Agency (JAEA)

K. Nishio, K. Hirose, H. Makii, R. Orlandi, K. Tsukada, M. Asai, A. Toyoshima, T.K.Sato, Y. Ito, Y. Nagame

University of York, JAEA

A.N. Andreyev

China Institute of Atomic Energy

S. Yan, C.J. Lin

Kindai University

Y. Aritomo, S. Tanaka, Y. Miyamoto, M. Okubayashi, S. Ishizaki

Tokyo Institute of Technology

K. Ratha, S. Chiba

University of Bordeaux

I. Tsekhanovich, B. Jurado

Kyoto University

T. Ohtsuki

ORNL

K. Rykaczewski, R.A. Boll

Collaborators

Tokai Campus, JAEATokyo

Tandem facility

J-PARC

20UR

Contents

☑ Multi-nucleon transfer (MNT) reactions and fission

☑ Experimental setup

☑ Experimental results and discussions

☑ Fission experiments using 254Es

☑ Summary

4

Nuclear Structure and Fission

5

Liquid drop model

Saddle Point

Ground state shape

scission

240U

Including shell energy correction

2nd Saddle point

Ground state shape

scission

Fission isomer

1st Saddle point

Fission fragment mass distributions is one of the important observable

to know the structure of deformed nucleus.

Highly excitation energy Low excitation energy

A.N. Andreyev, K. Nishio, K.-H. Schmidt, Reports on Progress in Physics, 81, 016301(2018)

Measured Fragment Mass/Charge Yield ~1995

Data for low-energy fissions,

Excitation energy ≦ Bf+10MeV

Measured Fission-Fragment Mass/Charge Yields ~2017

R. Léguillon et al., Phys. Lett. B 761, 125 (2016)

K. Hirose et al. Phys. Rev. Letters, 119, 222501 (2017)A.N. Andreyev, K. Nishio, K.-H. Schmidt, Reports on Progress in Physics, 81, 016301(2018)

②原子核構造（理論）Multi-nucleon transfer reactions and fission

In the multi-nucleon transfer (MNT) reactions:

(1) We can generate many nuclei depending on transfer channels.

(2) Excitation energy of compound nucleus distributes widely.

238U

18O

240U*…

16O...

238U

18O

Silicon ΔE-E

Ener

gy

Fission fragment detector

Fission

8Measured and Planned experiments using 18O beam and targets of 232Th, 238U, 248Cm, 237Np, 249Cf, 243Am, 249Bk, 254Es

(1) Fission probability and Fission barrier height.

(2) Fission fragment mass distributions.

(3) Fission fragment angular distributions.

(4) Prompt neutrons accompanied by fission.

Barrier

n

nLiquid Scintillator

(47 detetors )

Experimental Setup

recoilSilicon ΔE-E

DE

DE (75 μm)

12 detectors

E (300 μm)

16 strips

φ

θ

Multi-wire proportional Counter

Targets and Detectors

~ 30 - 60 μg/cm2

~ ø2.0 mm Position Sensitive

200 x 200 mm2

MWPCTarget (248Cm) Silicon ΔE-E detector

ΔE = 75 μm

Thickness fluctuation < 1 μm.

18O + 248Cm (Ebeam= 162MeV)

18O ( 248Cm*) 17O ( 249Cm*) 16O ( 250Cm*)

14C ( 252Cf*) 13C ( 253Cf*) 12C ( 254Cf*)

15N ( 251Bk*) 14N ( 252Bk*)

DE

(MeV

)

Eres (MeV)

Particle Identification using ΔE–E Telescope

O

F

N

C

B

Be

Liα

Elastic Scattering

Fission Probability and Fission Barrier Height

238U(18O, 16O)240U*E

ven

ts /

0.5

MeV

Even

ts /

0.5

MeV

Fis

sio

n P

rob

ab

ility

Excitation Energy (MeV)

238U(18O,16O)240U*

0 5 10 15 20 25

4000

8000

12000

0 5 10 15 20 25

300

600

900

0 5 10 15 20 25

0.1

0.2

0.3

2nd 3rdBf

Bfexp = 5.5 MeV

Excitation energy (MeV)

Fis

sio

n P

robabili

ty

of C

om

pound N

ucle

us

Bfcal = 6.38 MeV (P. Mӧller）

n

n

3rd

2nd

1st

Pote

ntial

Deformation

Fission after neutron evaporation is called “Multi-chance fissions”

238U(18O,17N)239Np*238U(18O,16N)240Np*

238U(18O,16C)240Pu* 238U(18O,15C)241Pu*

Bf(cal) =5.57 MeV 6.01 MeV

5.98 MeV

6.35 MeV

P. Mӧller et al.,

PRC 79, 064304 (2009)

Fission Barrier Height from MNT reactions

Excitation energy (MeV) Excitation energy (MeV)

Excitation energy (MeV) Excitation energy (MeV)

Fiss

ion

Pro

bab

ility

Fiss

ion

Pro

bab

ility

Fiss

ion

Pro

bab

ility

Fiss

ion

Pro

bab

ility5.92 MeV

B.N. Lu et al.,

PRC 89, 014323 (2014)

Poster Presentation by Kean Kun Ratha (PA13)

Extending the Fission Barrier Dａｔａ using MNT Reactions

Theory (KUYT)Theory (ETFSI)

Theory (Mӧller)

Available Data (33)RIPL-2, RMP (Bjornholm)

JAEA MNT Setup

4

8

12

16

20

U (Z=92)

Pu (Z=94)

Cm (Z=96)

Cf (Z=98)

Fm (Z=100)

Np (Z=93)

Am (Z=95)

Bk (Z=97)

Es (Z=99)

Md (Z=101)

130 140 150 160 170 180 1900

4

8

12

16

20

2468

1012

2468

1012

0.2 MeV

2468

1012

4

8

12

16

20

2468

1012

130 140 150 160 170 180 190

2468

1012

2468

1012

2468

1012

◇Planned at JAEA

We plan to obtain 34 new

fission barrier data using the

reaction of

18O +

237Np, 244Pu, 241,243Am, 248Cm, 249Bk, 249Cf, 254Es

〇

●

18

4

16

2

15

2

18

4

16

2

15

2

Neutron Number

Fis

sio

n B

arr

ier

Heig

ht

(MeV

)

4

8

12

16

20

U (Z=92)

Pu (Z=94)

Cm (Z=96)

Cf (Z=98)

Fm (Z=100)

Np (Z=93)

Am (Z=95)

Bk (Z=97)

Es (Z=99)

Md (Z=101)

130 140 150 160 170 180 1900

4

8

12

16

20

2468

1012

2468

1012

0.2 MeV

2468

1012

4

8

12

16

20

2468

1012

130 140 150 160 170 180 190

2468

1012

2468

1012

2468

1012

Fission Events registered on the Excitation Energy of Compound Nucleus

and Fragment Mass

Fragment Mass (u)

Exc

itat

ion

Ene

rgy

(MeV

)

60 80 100 120 140 160 1800

10

20

30

40

50

60

237Np(18O,19O)236Np*

Bf = 6.3 MeV

Fragment Mass (u)

Excita

tio

n E

ne

rgy (

Me

V)

Fission fragment

mass distributions

34.2 MeV

22.3 MeV

17.8 MeV

16.3 MeV

14.3 MeV

12.8 MeV

E*=12.3-13.3

E*=13.8-14.8

E*=15.8-16.8

E*=17.3-18.3

Fragment Mass (u)

Yie

ld (

%)

E*=21.75-23.75

E*=33.70-35.70

60 80 100 120 140 160 180012345012345012345

237Np(18O,19O)236Np p+235U (Ferguson) p+235U (Ferguson, Broadened with =4.0u)

012345012345

p+235U (Mulgin) p+235U (Broadened with =4.0u)

012345

Fragment Mass (u)Y

ield

(%

)

33.7-35.7 MeV

21.8-23.8 MeV

17.3-18.3 MeV

15.8-16.8 MeV

13.8-14.8 MeV

12.3-13.3 MeV

p + 235U = 236Np*

Ferguson (1973)

Mulgin (2009)

Benchmark of Fission Fragment Mass Distribution (FFMDs)

Excitation Energy

237Np (18O,19O) 236Np*

Present Data

Good agreement with the literature data is found.

Fission Fragment Mass Distributions (FFMDs) obtained in 18O + 237Np

Fragment Mass (u)

237Np 238Np 239Np 238Pu 239Pu240Pu 241Pu

240Am 241Am 242Am 243Am236Np

0

2

4

6

0

2

4

6

0

2

4

6

0

2

4

6

0

2

4

6

0

2

4

6

100 2000

2

4

6

100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200

7-10 MeV

10-20 MeV

20-30 MeV

30-40 MeV

40-50 MeV

50-60 MeV

60-70 MeV

100 200

Yie

ld (

%)

Fission data for 23 nuclides are obtained in the single experiment.

238-241Pu 240-243Am

243Cm 244Cm 245Cm 244Bk 245Bk246Bk 247

Bk246Cf 247Cf 248Cf 249Cf

242Cm

0

2

4

6

0

2

4

6

0

2

4

6

0

2

4

6

0

2

4

6

0

2

4

6

100 2000

2

4

6

100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200

7-10 MeV

10-20 MeV

20-30 MeV

30-40 MeV

40-50 MeV

50-60 MeV

60-70 MeV

100 200

242-245Cm 244-246Bk 246-249CfExcitation Energy (MeV)

50-60

30-40

20-30

10-20

5-10

40-50

60-70

236-239Np

18O + 232Th

18O + 238U

18O + 248Cm

Average Masses of Heavy（H） and Light （L） Fragments

Excitation Energy

Range

= 10 - 20 MeV

1st

chance

2nd

3rd

4th

Effects of Compound Nucleus Neutron-emission on FFMDs Role of Multi-chance Fission on FFMDs

Langevin Calculation240U (E*= 45 MeV)

Poster Presentation by Shoya Tanaka (PA10)

Experimental Data in Comparison with Langevin Calculation

Excitation Energy (MeV)

40-50

30-40

20-30

10-20

0

5

0

5

0

5

0

5

80 1600

5

80 160 80 160 80 160 80 160 80 160 80 160

Yield

(%

)

Fragment mass (u)

E* (MeV)

55

45

35

25

15

238Pu 239Pu 240Pu 241Pu 242Pu 243Pu 244Pu ( = 0.60) ( = 0.55)( = 0.55)( = 0.50)( = 0.50)( = 0.50)( = 0.45)

0

5

0

5

0

5

0

5

80 1600

5

80 160 80 160 80 160 80 160 80 160 80 160

236Np 237Np 238Np 239Np 240Np 241Np 242Np ( = 0.60) ( = 0.55)( = 0.55)( = 0.50)( = 0.50)( = 0.50)( = 0.45)

Yield

(%

)

Fragment mass (u)

E* (MeV)

55

45

35

25

15

0

5

0

5

0

5

0

5

80 1600

5

80 160 80 160 80 160 80 160 80 160 80 160

( = 0.50)( = 0.50)( = 0.45)( = 0.40) ( = 0.50)

Yield

(%

)

Fragment mass (u)

E* (MeV)

55

45

35

25

15

240U 239U 235U 238U 237U 236U 234U ( = 0.35) ( = 0.40)

With multi-chance fission

Without multi-chance fission

234,235,236,237,238,239,240U 236,237,238,239,240,241,242Np 238,239,240,241,242,243,244Pu

Experimental dataLangevin calculation by S. Tanaka, Kindai Univ.

Y. Aritomo and S. Chiba, Phys. Rev. C 88, 044614 (2013).

Fragment Mass (u)

Yie

ld (

%)

Data from 18O+232Th and 18O + 238U

N=146

Effects of Compound Nucleus Neutron-emission on FFMDs Neutron Multiplicity at the Excitation Energy corresponding to

Thermal Neutron-induced Fissions

● This work□ JENDL-4.0

Mass number of Fissioning Nucleus

ҧ𝜈Np Pu Am

Toward Understanding the Spins of Compound Nucleus

(1) Fission Probability F

issio

n P

rob

ab

ility

Excitation Energy (MeV)

Statistical Model Calculation

We are getting an evidence that

fission probability changes with

scattering angle.

238U

18O

240U*…

16O...

238U

18O

Fission probability changes with the spins of compound nucleus.

Fission fragment angular distribution has Information on spins of compound nucleus.

J (rotation) Axis

Ejectile

K

Fragment

Fragment

𝜃𝑓

Projectile

θ

φ

238U(18O,16O)240U*

W=

d

fiss/dW

(arb

.)cosqf

No Rotation

Toward Understanding the Spins of Compound Nucleus

(2) Fission Fragment Angular Distribution

We are getting an evidence that compound

nucleus spins are proportional to the number of

transferred nucleons.

258Fm

Literature data for Spontaneous fission

AsymmetricSharp

Symmetric

Fissions of Fermium and Heavier-element Isotopes

256Fm

254Es (T1/2=276 days)99

Multi-Mode Fissions

Standard mode

Several fission modes can coexist in heavy- & neutron-rich nuclei.

Mixture of three modes

Two cluster-like

A. Staszczak et al., Phys. Rev. C 80, 014309 (2009). 25

Neutron-rich Nuclei

Super-heavy Elements

254Es from Oak Ridge National Labratory

https://neutrons.ornl.gov/hfir

Fermium （element 100 ）

Einsteinium （99）

Californium （98）

Berkelium （97）

Curium （96）

0.3 μg of 254Es obtained in Oct 2017.

We plan to obtain it in 2019.

~ μg

~ ng

~ mg

Seed nuclides

4He

Start detector

254Es

Stop detector

Fragment 1

Fragment 2

Multi-wire proportional Counter

e-

Fragment

e-Film

Micro-channel Plate

Detector

In-beam fission measurement in 4He + 254Es = 258Md*101

27

254Es Target

（10 ng on Φ2mm）

BeamTarget

Fragment 2

Fragment 1

Double-Velocity Measurement

60 80 100 120 140 160 180 20050

100

150

200

250

300

TKEaverage

Q-value

Fragment mass (u)

TK

E （

MeV）

250Cf

Spontaneous Fission

60 80 100 120 140 160 1800

1

2

3

4

5

6

7

250Cf

Yie

ld (%

)

Fragment Mass (u)

Present

Hoffman

Fission of 250Cf and 258Md* (Preliminary Data)

254Es

D.C. Hofmann et al.,

Phys. Rev. C, 7, 276 (1973)

α

250Cf (Spontaneous Fission）

Yie

ld (

%)

To

tal K

ine

tic E

nerg

y (

MeV

)

Fragment mass (u)

Q-value

Hofmann

(1973) Present

β-250Bk

60 80 100 120 140 160 180 2000

1

2

3

4

5

6

7

258Md

Yie

ld (%

)

Fragment Mass (u)

Present

E* = 15.0 (MeV)60 80 100 120 140 160 180 200

50

100

150

200

250

300

350

TKEaverage

Q-value

Fragment mass (u)

TK

E （

MeV）

258Md

E* = 15.0 (MeV)

Fragment mass (u)

Yie

ld (

%)

4He + 254Es = 258Md ( Excitation energy 15.0 MeV )

To

tal K

ine

tic E

nerg

y (

MeV

)

4He

Q-value

Present

98 101

Summary

☑ Multi-nucleon transfer reaction is a powerful tool to study fission and to

take fission data. Fission data include information of MNT process itself.

☑ Effects of multi-chance fission on fission fragment mass distributions

are discussed.

☑ We plan to measure the fission barrier data up to mendelevium (Md),

the element 101.

☑ Assignment of the spins of compound nucleus is our next challenge.

☑ We started to obtain fission data for fermium region using 254Es, for the

strong benchmark of fission model. 29

25 – 27 March 2019, Tokai, Japan