Possibility for the production and study Possibility for the production and study of heavy neutron-rich nuclei of heavy neutron-rich nuclei

formed in multi-nucleon transfer reactionsformed in multi-nucleon transfer reactions

proposal for a new project at FLNRproposal for a new project at FLNR

V. Zagrebaev for PAC meeting, 16 June 2001

Unexplored area of heavy neutron rich nucleiUnexplored area of heavy neutron rich nuclei

fusion

fission

fragmentation

r-process and heavy neutron rich nucleir-process and heavy neutron rich nuclei

(1) difficult to synthesize(2) difficult to separate

Transfermium elementsTransfermium elements

(1) no more alpha-decays !(2) problem of Z identification

Multi-nucleon transfer reactionsMulti-nucleon transfer reactions as a method for synthesis of heavy neutron rich nucleias a method for synthesis of heavy neutron rich nuclei

andand

Stop in gas with subsequent resonance laser ionizationStop in gas with subsequent resonance laser ionizationas a method for extracting required reaction products (with a given Z value) as a method for extracting required reaction products (with a given Z value)

Production on NEW heavy nuclei in the region of N=126Production on NEW heavy nuclei in the region of N=126

“blank spot”

Production on new heavy nuclei in the Production on new heavy nuclei in the Xe + PbXe + Pb collisions collisions

Simulation of typical experiment in the laboratory frameSimulation of typical experiment in the laboratory frame

Test experiment demonstrated good agreement Test experiment demonstrated good agreement with our expectationswith our expectations

Schematic view of the setup for resonance laser ionization Schematic view of the setup for resonance laser ionization of nuclear reaction products stopped in gasof nuclear reaction products stopped in gas

The setup consists of the following elements (units)The setup consists of the following elements (units)

- front end system including: gas cell, system for extraction of the cooled ion beam, electrostatic system for final formation and acceleration of the ion beam (750 k$)

- laser system (900 k$)

- mass-separator (300 k$)

- system for delivery and cleaning of the buffer gas inside the gas cell,- vacuum system,- high voltage and radio frequency units,- diagnostic and control systems for the ion beam.

Required beams of accelerated ionsRequired beams of accelerated ions(the ion beams available at FLNR are well satisfied our requirements)(the ion beams available at FLNR are well satisfied our requirements)

Ions: 16,18О, 20,22Ne, …48Ca, 54Cr, …,86Kr, 136Xe, 238U (i.e., quite different depending on the problem to be solved).

Beam energies: 4,5 – 9 MeV/nucleon (slightly above the Coulomb barrier)

Beam intensity: not restricted (up to 1013 pps).

Beam spot at the target: 3–10 mm in diameter (not very important).

Beam emittance: 20 mm mrad.

Targets: different, including actinides Th, U, Pu, Am, Cm.

At target thickness 0.3 mg/cm2, ion beam of 0.1 pAand efficiency of the facility of 10% we will detect 1 event per secondat cross section of 1 microbarn

Similar setups at other laboratoriesSimilar setups at other laboratories(Jyväskylä: JYFL and ISOLDE)

Similar setups at other laboratoriesSimilar setups at other laboratories(Louvain-la-Neuve Radioactive Beam FacilityLouvain-la-Neuve Radioactive Beam Facility)

CYCLONE 30CYCLONE 110

CYCLONE 44

LISOL

Laser System

LASER ION SOURCE

Cyclotron beam

Gas CellSPIG

Extraction electrode

Gas from purifier

Front end of the LISOL mass separator

Yu.Kudryavtsev, SMI06, March 27-28, 2006

Excimer lasers

Dye lasers

SHGs

Reference cell

Towards LIS, 15 m

4/20

Max. Rep. Rate – 200 Hz

Laser System

Similar setups at other laboratoriesSimilar setups at other laboratoriesJapan, Tokai, KEK, RNB group of MiyatakeJapan, Tokai, KEK, RNB group of Miyatake(setup for 136Xe + 208Pb experiment)

A-, Z-separation

People already involved into discussion of the projectPeople already involved into discussion of the project

Leuven: M. Huyse, Yu. Kudryavtsev, P. Van Duppen

Jyväskylä : Juha Äystö, Iain Moore, Heikki Penttilä

GSI: Michael Block, Thomas Kühl

Mainz: Klaus Wendt

Manchester: Jonathan Billowes, Paul Campbell

FLNR: V. Zagrebaev, S. Zemlyanoi, E. Kozulin and others

Laser systemLaser system

type output power, (average) main & harmonics:(2nd ), {3rd & 4th}, Wt

pulse frequency, Hz

pulse length, ns

wave length, ns

Dye laser 3, (0.3) 104 10-30 213 - 850

Ti:Sapphire 2, (0.2), {0.04} 104 30-50 210 - 860

Eximer laser

30 400 10-20 308

CVL 30-50 103-104 10-30 510.6 & 578.2

Nd:YAG (80-100) 104 10-50 532

Production cost of the laser system with three-step resonance ionization Production cost of the laser system with three-step resonance ionization (combined with the corresponding optic scheme) is about(combined with the corresponding optic scheme) is about 900 k$. 900 k$.

Gas cell and Ion-guide systemGas cell and Ion-guide system

General requirements to the ion-guide systems look as follows: • pressure in gas cell: 100–500 mbar depending on energy of reaction products and required velocity of their extraction;• working gas is He or Ar (the latter looks preferably because its stopping capacity and effectiveness of neutralization are higher);• gas purity not lower than 99,9999%;• cell volume is about 100–200 sm3;• vacuum in intermediate camera not worse than10-2 mbar;• vacuum in the entrance into the mass separator is 10-6 mbar; Some specific requirements, stipulated by the use of the resonance laser ionization, should be also taken into account:

• gas cell should be two-volume to separate the area of thermalisation and neutralization from the area of resonance laser ionization;• extraction of ions from the cell and driving them into the mass separator have to be provided by the sextopole (quadrupole) radio-frequency system which allows one to increase the effectiveness of the setup and to perform ionization of atoms in the gas jet outside the cell; • the input-output setup must be supplied by the system of optical windows and by the system of explicit positioning (0.3 mm) of the gas cell, guide mirrors and prisms. Production cost of the gas cell and ion output systems is about Production cost of the gas cell and ion output systems is about 750 k$.750 k$.

Mass separatorMass separator

All extracted ions have charge state +1 because only neutral atoms are ionized to this state by the lasers while all “non-resonant” ions are removed by electric field before reaching the area of interaction with laser radiation. In this case the extracted particles can be easily separated by masses in dipole magnet. For low-energy (30–60 keV) beams of +1 charged ions no specific requirements are needed for the dipole magnet. It could be a standard magnet separator similar to ISOLDE II, for example: • turning angle 40о–90о,• turning radius of about 1–1.5 m, • focal length of about 1 m,• rigidity of about 0.5 Т/m. Mass resolution is the only critical parameter which should be not less than 1500 (4000 is theoretically feasible). Camera of the separator must have an optical input if collinear laser ionization is used with the sextupole ion-guide (SPIG). Production cost of such mass separator is about Production cost of such mass separator is about 300 k$.300 k$.