The BECQUEREL Project: Progress Report for Years 2006-8 and Plans for 2009-11

1. The BECQUEREL Project: Progress Report for Years 2006-8 and Plans for 2009-11 D. A. Artemenkov, V. Bradnov, A. I. Malakhov, D. O. Krivenkov, P. A. Rukoyatkin, V. V. Rusakova, T. V. Shchedrina, P. I. Zarubin, I.G Zarubina V. I. Veksler and A. M. Baldin Laboratory of High Energy Phyiscs,JINR, Dubna, Russia M. M. Chernyavsky, S. P. Kharlamov, S. G. Gerasimov, L. A. Goncharova, G. I. Orlova, N. G. Peresadko, N. G. Polukhina P. N. Lebedev Physical Institute RAS, Moscow, Russia М. Haiduc, A. Neagu,E. Stefan Institute of Space Sciences, Bucharest-Magurele, Romania A. A. Moiseenko, V. R. Sarkisyan Erevan Physical Institute, Erevan, Armenia R. Stanoeva Institute for Nuclear Research and Nuclear Energy BAS, Sofia, Bulgaria S. Vokal Safarik University, Kosice, Slovakia

2. Nuclear beams of energy higher than 1A GeV are recognized as a novel opportunity for the nuclear structure explorations. Among all variety of the nuclear interactions the peripheral dissociation bears uniquely complete information about the excited nucleus states above particle decay thresholds. The BECQUEREL Project (Beryllium (Boron) Clustering Quest in Relativistic Multifragmentation) at the JINR Nuclotron is devoted systematic exploration of clustering features of light stable and radioactive nuclei. A nuclear track emulsion is used to explore the fragmentation of the relativistic nuclei down to the most peripheral interactions - nuclear "white" stars. This technique provides a record spatial resolution and allows one to observe the 3D images of peripheral collisions. The analysis of the relativistic fragmentation of neutron-deficient isotopes has special advantages owing to a larger fraction of observable nucleons.

3. Nuclear Track Emulsions Superposition of microphotographs of interaction of relativistic nucleus 32Sand human hair taken with MBI-9 microscope and NIKON camera

4. NUCLOTRON: 2.1 А GeV14N 132 events 1.2A GeV 14N → 3He + H 50 “white” stars (2 events 6He+3He+4He+1H) Tatjana Shchedrina

5. Physics Program Nuclear Clustering

6. CO2 laser

7. Zpr/Apr = 4/910B → 9Be .

8. 370 events 1.2 A GeV 9Be→2He +1.7 MeV 144 “white” stars 27 stars with target proton recoil (g-particle) 39 stars with heavy fragment of target nucleus (b-particle) Denis Artemenkov

9. 0+,8Be(92 KeV, 6.8 eV) 2+,8Be(2.9 MeV, 1. 5 MeV)

10. Suggested analysis: 2000 events 9Be + p → 2α Nadezhda Kornegrutsa

11. Zpr/Apr = 4/77Li → 7Be

12. MeV 1.6 6.9 25.3 21.2 5.6

13. Zpr/Apr = 5/810B → 8B

14. Diagram of peripheral dissociation of relativistic 8B nucleus in EM field of Ag nucleus Nearer approach of the nuclei with an impact parameter (a), absorption of quasireal photon by 8B nucleus (b), 8B dissociation on fragment pair - p and 7Be (c).

15. 8В (1.2 AGeV)→ 7Ве + p Ralica Stanoeva

16. 8B→23He +2H

17. Zpr/Apr = 2/3 12C → 9C

18. Major task: analysis of9Сexposure Dmitry Krivenkov

19. Zpr/Apr = 5/12 12C → 12N

20. Suggested10Cexposure

21. 10С

22. 1.0 A ГэВ10B→23Не+4Не

23. Suggested11Cexposure

24. 2.0 A GeV 11B→4Не+7Be

25. CONCLUDING REMARKS The presented observations serve as an illustration of prospects of the Nuclotron for nuclear physics and astrophysics researches. In spite of an extraordinarily large distinction from the nuclear excitation energy the relativistic scale does not impede investigations of nuclear interactions down to energy scale typical for nuclear astrophysics, but on the contrary gives advantages. The major one of them is the possibility of principle of observing and investigating multi-particle systems. The investigations with light nuclei provide a basis for challenging studies of increasingly complicated systems He – H - n produced via multifragmentation of heavier relativistic nuclei in the energy scale relevant for nuclear astrophysics. In this respect, the motivated prospects are associated with a detailed analysis of the already observed fragment jets in the events of EM&Diffractive dissociation of Au nuclei at 10.6A GeV and Pb nuclei at 160A GeV. Due to a record space resolution the emulsion technique provides unique entirety in studying of light nuclei, especially, neutron-deficient ones. Providing the 3D observation of narrow dissociation vertices this classical technique gives novel possibilities of moving toward more and more complicated nuclear systems. Therefore this technique deserves upgrade, without changes in its detection basics, with the aim to speed up the microscope scanning for rather rare events of peripheral dissociation.

26. 3.65A GeV 28Si 2+2+2+2+2+2+1

27. NUCLOTRON: 1A GeV 56Fe Elena Stefan Alina-Tania Neagu

28. SPS: 158 A GeV/c Pb 2 3 1 4 5 6

33. Запрос на приобретение электронной аппаратуры формирования пучков на 2009-11 гг. Итого: 20000 Euro (7000 Euro в год)

35. 8В (1.2A GeV) → 2Не + Н

36. Measured Chargesof Secondary Fragments of 8ВNucei Density ofδ-electrons per1 ммlength of beam particles Zfr > 2.

37. 8B: Total PT (7Be+p) EMD “white”stars nh≠0