Dubna, January, 2007

Programme Advisory Committee for Nuclear Physics

28th meeting, 19-20 June 2008

RECOMMENDATIONS  

WALTER GREINER

PreambleThe Chairperson of the PAC, Walter Greiner, welcomed

the PAC members, in particular the new members C. Beck, V. Ostashko, O. Zimmer, the expert Z. Vilakazi, the ex-officio members from JINR, and presented the implementation of the recommendations taken at the previous meeting.JINR Vice-Director M. Itkis informed the PAC about the Resolution of the 103rd session of the Scientific Council (February 2008) and about the decisions of the Committee of Plenipotentiaries (March 2008).

The PAC was pleased to learn about the visit to JINR, on 18 April 2008, of the President of the Russian Federation, D. Medvedev. Together with leaders of government agencies and regions of the host country, the President was presented with information on the research work of the Flerov Laboratory of Nuclear Reactions, in particular on the discovery of superheavy elements, and on other areas of the Institute’s activity.  

3

 

Status and prospects of investigations on the theme “Synthesis of New Nuclei and Study of Nuclear Properties

and Heavy-Ion Reaction Mechanisms”

The PAC discussed in detail the status and mentioned trends of possible investigations within the theme “Synthesis of New Nuclei and Study of Nuclear Properties and Heavy-Ion Reaction Mechanisms”, presented in the report by FLNR Scientific Leader Yu. Oganessian. The PAC endorses the activity of the FLNR, in line with the previous recommendations of the PAC, aimed at modernizing the cyclotrons and extending the experimental potential of the Laboratory. However, taking into account the need of a new perspective of studies of both neutron-rich light nuclei and superheavy nuclei, the PAC invites the Laboratory to work out a long-range programme of further developments of the accelerator complex and of state-of-the-art experimental facilities of the next generation.

The main purpose is the quantitative increase of the efficiency of experiments as a whole by at least one order of magnitude to allow the Laboratory to keep its leadership during the next decades.

neutrons

prot

ons

50

82

82

28

50

5028

20

20

8

82

2

126

H. Jensen, E.P. Wigner and M. Goeppert-MayerNobel prize 1963Nuclear shellsNuclear shells Heaviest nuclei

Exotic area

Lightest nuclear

?

Yu. Oganessian. Heavy Ion Physics in JINR. 28-th PAC meeting, June 19-20, JINR, Dubna

n

Be

B

C

B

N

F

Ne

10

12

6

6

4

4

2

20

8

8

O

He

Li

no shell effectwas observed

evidence of shell structure

strong shell effect in the “doubly-magic” nucleus

unbound

S2n = -1.07 MeV A.N. Ostrowski et al., HMI 1994

S2n = -1.2 MeV A.A. Korsheninnikov et al., RIKEN 1994

S2n = -3.0 MeV G.M. Ter-Akopian et al., FLNR 2008

core

2n- halo

discovery “di-neutron”

in halo-nucleus 6HeFLNR 2001

““Blanc spot” on the Nuclear ChartBlanc spot” on the Nuclear Chart

blancspot

fragmentation(spallation)

fusion

New theoretical concepts require more detailed data on the structure of neutron and proton rich nuclei.

Further development of the DRIBs complex will allow one to carry out these investigations much more efficiently.

On the way to the first Island of StabilityOn the way to the first Island of Stability

“cold” fusion reactions:208Pb + 64Ni, 70Zn, … → 272110, 278112, …

“hot” synthesis:238U, 244Pu, 248Cm, 249Cf + 48Ca → 286112,292114 ,296116 ,297118

242Pu, 245Cm244Pu, 248Cm

113/282

10.63

73 ms

111/2 87

10.69

4.2 ms

109/2 47

9.76

0.45 s

107/2 07

105/266

104/268

0.37 h

a

a

a

a

8.93

1 min

237Np

115/287

10.59

3 ms2

113/283

10.12

0. s1

111/279

10.37

0.17 s

109/2 57

10.33

9.7 ms

107/2 17

105/267

1.2 h

a

a

a

a

a

109/276

9.71

0.72 s

107/272

9.02

9.8 s

113/284

10.00

0.48 s

115/288

10.46

87 ms

105/268

1.2 d

111/280

9.75

3 6. s

104/268

a

a

a

a

a

243Am

249Cf

DecaychainsDecaychains

34 nuclides

85 decay chains

was registered

48Ca +FLNR 2000-2006

Recommendation:

The PAC strongly recommends to start a detailed consideration of a long-term plan for the development of the FLNR accelerator complex and experimental facilities.

It should be presented at the next PAC meeting.

Recommendations on the themes previously approved for completion in 2008

Nuclear Theory

The PAC took note of the report on the closing theme “Nuclear Theory” (01-3-1029-99/2008) and the proposal for a theme “Nuclear Structure and Dynamics”. The PAC highly appreciates the results obtained in the main research directions: nuclear structure far from the stability valley, nucleus-nucleus collisions at low energies, few-body systems, nuclear dynamics at relativistic energies, properties of hot and dense nuclear matter. The PAC also appreciates the educational activities of BLTP and relations of theoretical studies to the JINR experimental programme.

The PAC supports the continuation of nuclear theory activities under a new theme that should incorporate a complex and broad view on the various aspects of nuclear structure and dynamics.

Nuclear Theory

Project Leader

1. Nuclear structure V.V. Voronov far from stability valley A.I. Vdovin J. Kvasil

2. Nucleus-nucleus collisions R.V. Jolos and nuclear properties N.V.Antonenko at the low energies

Nuclear Theory

Project Leader

3. Exotic few-body systems A.K.Motovilov V.B.Belyaev

4. Nuclear structure and V.V. Burov dynamics at the relativistic S.N.Ershov energies M.Gaidarov

Continuum spectroscopy of two-neutron halo nucleiContinuum spectroscopy of two-neutron halo nuclei

S.N. Ershov, B.V. Danilin, J.S. Vaagen ( Phys. Rev. C74 (2006) 014603 )

0.0 0.5 1.00

1

2

0+

1-

2+

Wp

h (

En

n /

E

)

Enn

/ E

1 < E < 3 MeV

0.0 0.5 1.00

1

2

1 < E < 3 MeV

0+

1-

2+

Wp

h (

EC

n /

E

)

ECn

/ E

-1 0 10.0

0.5

1.0

0+

1-

2+

W (

co

s n

n )

cos (nn

)

-1 0 10.0

0.5

1.0

0+1-

2+

W (

co

s C

n)

cos (Cn

)

L.V. Chulkov et al., Nucl. Phys. A759, 23 (2005)■

n n

C

xyxyn nx

C

yxy

Theoretical analysis of various angular and energy correlations of the three fragments in 6He breakup on 208Pb at collision energy 240 MeV / nucleon have been performed. The analysis has been based on a microscopic four-body distorted wave approach to breakup reactions and uses the three-body model for the nuclear structure of the two-neutron Borromean halo nucleus 6He.

6He + A → n→ n11 + n + n22 + + 44He + A’He + A’

The kinematically complete breakup The kinematically complete breakup reactionreaction

Correlations between fragmentsin different Jacobi coordinate systems

Microscopic theoretical analysis of the 6He+p elasticand 6He+28Si reaction cross sections

The microscopic optical potential was constructed and applied to analyse the experimental data of FLNR JINR and the other centers. We tested the three current models of 6He+p: Tanihata's, COSMA (M.Zhukov et al) and LSSM (S.Karataglidis et al).

microoptU

Total reaction cross-section without

collective excitation included

Total reaction cross-section with collective

excitation included

The model density distributions

LSSM LSSM

Recommendation. The PAC recommends approval of the new theme "Nuclear Structure and Dynamics" for the years 2009–2013 with first priority.

Educational Programme

The PAC took note of the report on the theme “Organization, Maintenance, and Development of a University-Type Education Process” (06-0-1026-98/2008). The PAC supports the proposal by the UC Director concerning the increase of the budget required to complete the creation of student laboratories and to enlarge the number of PhD students.

Today you heard report D. Fursaev.I leave comment of education programme.Recommendation. The PAC recommends extension of this

theme for the years 2009–2013 with first priority. A detailed educational programme including the list of lectures, lecturers and time table should be presented at the next PAC meeting. The possibility for licensing the status of the PhD students, especially for the Member States, should be examined.

IREN

The PAC took note of the report on the theme “Construction of the IREN facility” (03-4-0993-94/2008). The PAC highly appreciates the efforts of the JINR Directorate and the laboratories involved in the implementation of this project. The plans to start up the facility at the end of 2008 seem to be realistic. The PAC also appreciates the efforts of the FLNP Nuclear Physics Department on preparation of the experimental infrastructure at IREN Phase I.

V. Shvetsov had talk about IREN yesterday.Recommendation. The PAC recommends that the

theme “Construction of the IREN facility” be finished in 2008, and the financial resources for the maintenance, operation and development of the IREN facility be kept within the theme “Nuclear Physics with Neutrons –– Fundamental and Applied Investigations”.

•First experiment at IREN-1:

• measurement of capture cross section for 181Ta: demonstration experiment

• Experimental program:

• cross section measurements for nuclear engineering and nuclear astrophysics

• (n,p), (n,a) reactions

• nuclear structure studies: search for vibrational resonances in stable nuclei

• search for subthreshold p-resonance in Pb

• search for PT-violation in neutron-nucleus interactions

• neutron activation analysis

• isotope production

A number of preliminary experiments which are valuable themselves should be performed at IREN facility:

1. Study of resonance spectra of promising isotopes: energies, widths, spins, parities and p1/2-p3/2 channel mixing of neutron resonances.

2. Gamma-spectra of the resonances which are promising for the discussed purposes, linear polarization of the lines of interest.

3. P-violation effects in γ-transitions induced by neutrons of the resonance energy.IREN is capable to measure P-violation effect up to 10-3 for an intensive gamma-line.

The versions of the approach aimed to search for PT-invariance break up seem to be a way to reduce upper limit of the PT-invariance break up effect achieved recently in nuclear experiments by several orders of magnitude and approximate it to the level of accuracy attained in permanent EDM measurements for isovector PT-noninvariant amplitude.

SEARCH FOR PT-INVARIANCE BREAK UP

Recommendation

The PAC recommends concentrating available human, financial and technical resources of the FLNP Nuclear Physics Department mainly on the realization of the proposed scientific programme for IREN-1 and on the development and preparation of the programme for the full-scale IREN facility.

 

Poster session

The PAC was particularly pleased with the presentations of new results and proposals by 13 young scientists in the field of nuclear physics research. This type of presentations should be continued in future.  

Scientific reports

The PAC heard with interest the report “Reactions with exotic nuclei at FLNR”, presented by V. Zagrebaev. The experiments discussed in the report are strongly connected with the realization of the DRIBs programme, in particular its application to studies of astrophysical importance, also with the use of beams heavier than 6He.

The PAC heard with interest the scientific report, presented by V. Belyaev, on the application of few-body methods to the calculation of triple processes in astrophysics. In particular, his evaluation of K-capture in p+7Be process demonstrates the importance of the method for the exact calculation of the solar neutrino flux.

 

Next meeting of the PAC

The next meeting of the PAC for Nuclear Physics will be held on 22–23 January 2009. Its tentative agenda will include:

•Reports and recommendations on the themes and projects to be completed in 2009•Consideration of new projects•Research programme at the LEPTA facility•Status of the EDELWEISS experiment•Poster presentations of new results and proposals by young scientists in the field of nuclear physics research•Scientific reports.

Thank you very much for your attention

Low-energy multi-nucleon transfer (Zagrebaev & Greiner, Phys. Rev. Letters, 2008 )