Multinuclean transfer research at JINR�Recent results and plans�����Alexander Karpov���FLNR, Joint Institute for Nuclear Research

8th International Workshop on Nuclear Dynamics in Heavy-ion Reactions, August 21-25, 2026

Methods of synthesis of new nuclei

Fusion:

+ any element (question of probability)

- lack of neutrons

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Fragmentation:

+ very efficient and universal

- products are lighter than ²³⁸U

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Fission:

+ neutron-rich products

- products are much lighter than ²³⁸U

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Multinucleon transfer (MNT):

+ a way to unknown regions

• very, very complicated� technically
• lack of experimental data

Fusion

Fragmentation

Fission

162

MNT?

Production of neutron-rich nuclei. Os-isotopes

Yield(fragmentation)� = k >< 1�Yield(MNT)

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k include:

• thinner target
• much smaller separation efficiency
• usually larger beam intensity
• etc.

?

Deep inelastic collisions,

Quasi-fission

Sequential fission

Fusion

Fusion-fission

Fusion-survival

Mechanisms of reactions induced by heavy ions at near barrier energies

MNT features:

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• numerous (Z,A) exit channels

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• wide angular and energy distributions

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• strong change of kinematic characteristics�depending on the exit channel of interest

experiment

modelling

Georgy N. Flerov��Synthesis and study of new isotopes and elements�Report at the Conference “100 years of M. Curie”�October 1967

• Considerably more promising are the synthesis and study of new isotopes and elements in reactions involving the merging of heavy nuclei, enabling compound nuclei of the ⁴⁷⁶184 type (²³⁸U + ²³⁸U) to be obtained.

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• Such compound nuclei will undergo fission almost instantaneously. However, among their fragments there may be nuclei of element 114 with a high mass number. We may well expect a relatively high yield of superheavy element nuclei with long half lives among the fission fragments.

Modelling

A.V. K., V. Saiko, Phys. Rev. C, 2017, 2019

Production of neutron-rich nuclei with N=126

Optimal energy

N=126

Iridium isotopes (Ir-191)

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¹³⁶Xe+¹⁹⁸Pt

target

E_c.m.=420 MeV

450 MeV

643 MeV

-1p -6n

Ir-191

all Ir isotopes

N=126

Iridium isotopes (Ir-203)

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¹³⁶Xe+¹⁹⁸Pt

target

E_c.m.=420 MeV

450 MeV

643 MeV

-1p +6n

Angular distributions

Ir-203

all Ir isotopes

100 nb

100 nb

N=126

100 nb

⁴⁸Ca+²⁵¹Cf

E = 6.1 MeV/n

A.V.K., V.V. Saiko, Phys.Part.Nucl., 2019

¹³⁶Xe+²⁵¹Cf

E = 7.0 MeV/n

A.V.K., V.V. Saiko, Phys.Part.Nucl., 2019

²³⁸U+²⁵¹Cf

E = 8.8 MeV/n

N=162

A.V.K., V.V. Saiko, Phys.Part.Nucl., 2019

Production of neutron-rich nuclei with N=126

Stable vs. Radioactive beams

Yield ~ cross section · beam intensity

V.V. Saiko and A.V. Karpov, Phys. Rev. C 109, 064607 (2024)

Phys. Rev. C 112, 064609 (2025)

FLNR ACCELERATOR COMPLEX

Velocity filter

Separator for Heavy ELement Spectroscopy (SHELS)

Pros:

• Detection and identification of MNT products
• Work at sub micro barn cross sections

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Cons:

• Experiments at forward angles

H.M. Devaraja, et al., PLB 862, (2025) 139353

Studying the ²³⁸U + ²³⁸U reaction

²³⁸U

²³⁸U

2

Multinucleon transfer processes in U + U reaction

(!)

excited

Studying the ²³⁸U + ²³⁸U reaction

²³⁸U

²³⁸U

2

fission

Multinucleon transfer processes in U + U reaction

excited

cold

questions:

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• cross sections for primary heavy products
• cross sections for survived heavy products
• excitation energies
• various correlations of Z, A, θ, E

new CORSET

(access to MNT dynamics)

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pros:

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• wide angular range

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• coincidence of 2-3 fragments

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• deriving of characteristics of primary (ToF-ToF) as well as final fragments (ToF-E).

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• M-θ-E correlations

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cons:

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• lack of Z identification

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• accuracy of M measurement is ~2-3 u

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• limit of cross section is ~1μb

¹³⁶Xe + ²³⁸U: Phys. Rev. C 109, 034616 (2024)

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²⁰⁹Bi + ²³⁸U: Phys. Rev. C 112, 014625 (2025)

Experiments ¹³⁶Xe,²⁰⁹Bi+²³⁸U

excitation energies

binary and triple coincidences

mass-energy correlation

FLNR 2030

What do we need?

What do we have?

STAR

(Separator for TransActinide Research)

²³⁸U + ²³⁸U →

~ ²⁶⁸No + ~ ²⁰⁸Pb

System for Correlated Investigation of Fragments (SCIF)

SСIF consists of:

Study of mechanisms of fusion-fission and incomplete fusion reactions

CORSET Neutron - measuring mass-energy in coincidence with accompanying neutron and gamma emission;

CORSET Gamma - measuring mass-energy in coincidence gamma spectroscopy;

SuperCORSET - provides precise (A,Z) identification of fragments with masses up to 200 a.m.u. in a broad angular range;

Key questions on MNT dynamics

• Cross sections for formation of neutron-enriched nuclei. Their dependence on collision energy.

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• Angular distributions of various products (both proton- and neutron-rich) of reactions of multinucleon transfer.

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• Energetics of multinucleon transfer: kinetic energies of fragments, their excitation energies (and thus survival).

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• Search for optimal projectile-target combinations (projectile: ⁴⁸Ca, ¹³⁶Xe, ²³⁸U…) for production of transuranic nuclei (not discussed in this talk).

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• Role of target/projectile deformations as well as their magicity in dynamics of the MNT reactions.

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Investigations may go in two ways: with detection of survived products (low cross sections) and with detection of the sequential fission products (3 fragments, high cross sections).