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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 Technology

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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, JAEA

Tokyo Tandem facility J-PARC

20UR

Contents

☑ Multi-nucleon transfer (MNT) reactions and fission ☑ Experimental setup ☑ Experimental results and discussions ☑ Fission experiments using 254Es ☑ Summary

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Nuclear Structure and Fission

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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 Energy Fission fragment detector Fission

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Measured 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 n

Liquid Scintillator (47 detetors )

Experimental Setup

recoil

Silicon 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 MWPC Target (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 Li α

Elastic Scattering

Fission Probability and Fission Barrier Height

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

5 10 15 20 25 5 10 15 20 25 0.1 0.2 0.3

2nd 3rd

Bf

Bf

exp = 5.5 MeV

Excitation energy (MeV)

Fission Probability

• f Compound Nucleus

Bf

cal = 6.38 MeV (P. Mӧller）

n n

3rd 2nd 1st

Potential 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) Fission Probability Fission Probability Fission Probability Fission Probability 5.92 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)

130 140 150 160 170 180 190 4 8 12 16 20 2 4 6 8 10 12 2 4 6 8 10 12

0.2 MeV

2 4 6 8 10 12 4 8 12 16 20 2 4 6 8 10 12 130 140 150 160 170 180 190 2 4 6 8 10 12 2 4 6 8 10 12 2 4 6 8 10 12

◇

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

• 184

162 152 184 162 152

Neutron Number Fission Barrier Height (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)

130 140 150 160 170 180 190 4 8 12 16 20 2 4 6 8 10 12 2 4 6 8 10 12

0.2 MeV

2 4 6 8 10 12 4 8 12 16 20 2 4 6 8 10 12 130 140 150 160 170 180 190 2 4 6 8 10 12 2 4 6 8 10 12 2 4 6 8 10 12

Fission Events registered on the Excitation Energy of Compound Nucleus and Fragment Mass

60 80 100 120 140 160 180 10 20 30 40 50 60

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

Bf = 6.3 MeV

Fragment Mass (u) Excitation Energy (MeV)

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) Yield (%)

E*=21.75-23.75 E*=33.70-35.70

60 80 100 120 140 160 180 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5



1 2 3 4 5 1 2 3 4 5



1 2 3 4 5

Fragment Mass (u)

Yield (%)

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 239Pu 240Pu 241Pu 240Am 241Am 242Am 243Am 236Np 2 4 6 2 4 6 2 4 6 2 4 6 2 4 6 2 4 6 100 200 2 4 6 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200

1 2 3 4 5 6

100 200

Yield (%)

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

238-241Pu 240-243Am

243Cm 244Cm 245Cm 244Bk 245Bk 246Bk 247Bk 246Cf 247Cf 248Cf 249Cf 242Cm 2 4 6 2 4 6 2 4 6 2 4 6 2 4 6 2 4 6 100 200 2 4 6 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 200 100 20

242-245Cm 244-246Bk 246-249Cf

Excitation 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 Calculation

240U (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

5 5 5 80 160 5 80 160 80 160 80 160 80 160 80 160 80 160

Fragment mass (u)

      

5 5 5 80 160 5 80 160 80 160 80 160 80 160 80 160 80 160

      

Fragment mass (u)

5 5 5 80 160 5 80 160 80 160 80 160 80 160 80 160 80 160

    

Fragment mass (u)

 

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 data

Langevin calculation by S. Tanaka, Kindai Univ.

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

Fragment Mass (u) Yield (%)

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

ҧ 𝜉

Np Pu Am

Toward Understanding the Spins of Compound Nucleus (1) Fission Probability

Fission Probability 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

𝜄𝑔

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

Asymmetric Sharp 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).

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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

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254Es Target

（10 ng on Φ2mm）

Beam Target Fragment 2 Fragment 1

Double-Velocity Measurement

60 80 100 120 140 160 180 200 50 100 150 200 250 300

TKEaverage Q-value

TKE （ MeV）

250Cf

60 80 100 120 140 160 180 1 2 3 4 5 6 7

250Cf

Yield (%)

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）

Yield (%)

Total Kinetic Energy (MeV)

Fragment mass (u) Q-value

Hofmann (1973) Present

β-250Bk

60 80 100 120 140 160 180 200 1 2 3 4 5 6 7

258Md

Present

E = 15.0 (MeV)

60 80 100 120 140 160 180 200 50 100 150 200 250 300 350

TKEaverage Q-value

TKE （ MeV）

258Md E = 15.0 (MeV)

Fragment mass (u) Yield (%)

4He + 254Es = 258Md

( Excitation energy 15.0 MeV )

Total Kinetic Energy (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.

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25 – 27 March 2019, Tokai, Japan