Работа сотрудничества в 2005 г. П. И. Зарубин ОИЯИ

Clustering building blocks: more than one nucleon bound, stable & no exited states below particle decay thresholds – deuteron, triton, 4 He, and 3 He nuclei

Mg-Si Dissociation into charge state proton

14 N Dissociation with 8 Be like fragmentation 3 after proton

Dubna: Relativistic Nuclei

Secondary beams of light radioactive nuclei will be produced mostly via charge exchange reactions. 8 B and 9 Be beams has been formed via fragmentation of 10 B.

1.a limiting fragmentation regime is set in, 2. the reaction takes shortest time, 3. fragmentation collimated in a narrow cone – 3D images, 4. ionization losses of the reaction products are minimum, 5. detection threshold is close to zero. Advantages of relativistic fragmentation

dN/dT n T n =(M* n - n M )/(4 n ), MeV A GeV/c 12 C: =0.4 MeV

4.5 A GeV/c 16 O

4.5A GeV/c 24 Mg Peripheral Dissociation into charge state with 8 Be and 12 C * like fragments

The common topological feature for fragmentation of the Ne, Mg, Si, and S nuclei consists in a suppression of binary splittings to fragments with charges larger than 2. The growth of the fragmentation degree is revealed in an increase of the multiplicity of singly and doubly charged fragments up to complete dissociation with increasing of excitation. This circumstance shows in an obvious way on a domination of the multiple cluster states having high density over the binary states having lower energy thresholds.

Alpha-particle condensation in nuclei P. Schuck, H. Horiuchi, G. Ropke, A. Tohsaki, C. R. Physique 4 (2003) At least light nα-nuclei may show around the threshold for nα disintegration, bound or resonant which are of the α-particle gas type, i. e., they can be characterized by a self-bound dilute gas of almost unperturbed α-particles, all in relative s-states with respect to their respective center of mass coordinates and thus forming a Bose condensed state. Such state is quite analogous to the recently discovered Bose condensates of bosonic atoms formed in magnetic traps. The only nucleus, which shows a well-developed α-particle structure in its ground state is 8 Be. Other nα-nuclei collapse in their ground states to much denser system where the α-particles strongly overlap and probably loose almost totally their identity. When these nα-nuclei are expanded, at some low densities α-particles reappear forming a Bose condensate. If energy is just right, the decompression may stall around the α-condensate density and the whole system may decay into α- particles via the coherent state. 12 C3 α, …., 40 Ca10 α, 48 Cr3 16 O, 32 S 16 O+4 α

The Q distribution for the fragmentation channels 22 Ne n. Q = (M*-M)/A

The b ik distribution for the fragmentation channels 22 Ne n b ik =-(P i /m i -P k /m k ) 2

Boltzmann constant, k /approx eV K -1 Typical Temperature Range, Ŧ /approx K per α p α =(2m α T α ) p α /approx MeV Planck constant, ħ /approx 200 MeV fm λ=ħ/p de Broglie wave lengths /approx 1-10 fm λ coh α /approx R α λ coh He /approx R He T α /T He = Ŧ α / Ŧ He = (R He /R α ) 2 /approx Macroscopic quantum coherence phenomena in atomic physics /approx 1 K Macroscopic quantum coherence phenomena in nuclear physics /approx K

Deuteron-Alpha Clustering in Light Nuclei 10 B(19.9%) 6 Li(7.5%) 14 N(99.634%) 50 V(0.25%) d

2.9A GeV/c 14 N Dissociation 14 N nucleus, like the deuteron, 6 Li and 10 B, belong to a rare class of even-even stable nuclei. It is interesting to establish the presence of deuteron clustering in relativistic 14 N fragmentation.

2.1 A GeV 14 N By systematic scanning over primary tracks, 42 «white» stars have already been found among 540 inelastic events. The secondary tracks of «white» stars are concentrated in a forward 8° cone. They are distributed over the charge modes as follows: 3He+H - 33%, C+H - 31%, B+2H - 7%, B+He - 7%, Be+He+H - 2%, Li+He+2H - 2%, Li+4H 2%.

M *2 =(ΣP j ) 2 =Σ(P i P k ) Q 3 =M * -M c

14 N 3

1.9 A GeV 10 B 10 B is disintegrated to 2 doubly charged and 1singly charged particles in 70% of white stars. A singly charged particle is the deuteron in 40% like in case of 6 Li. 8 Be contribution is 20%. 10 В 9 Bep – 3%

1.3A GeV 9 Be dissociation in B 9 Be, Nuclotron, white star with recoil proton with heavy fragment of target nucleus

The Q 2α distribution for the fragmentation channels 9 Be 2. M *2 =(ΣP j ) 2 =Σ(P i P k ) Q 2 =M *- M 2

=1.5 MeV =0.092 MeV =0.23 MeV =1.4 MeV =1.58 MeV 5 Li 6 Be 7B7B 8C8C 11 N Toward stability frontier

Splitting to HeHe with two target fragments, HeHe, HeHH, 6 Lip, and 4H. 2 A GeV/c 7 Be.

2 A GeV/c 10 B 8 B

Ternary H&He Process + 8 B s The 10 B nuclei with a momentum of 2A GeV/c and an intensity of about 10 8 nuclei per cycle were accelerated at the JINR nuclotron. A beam of secondary nuclei of a magnetic rigidity corresponding to Z/A = 5/8 ( 10 В 8 B fragmentation) was provided for emulsions. We plan to determine the probabilities 8 B 7 Bер (18), 3,4 He 3 Hep (11), HeHHp (12), 6 Lipp (1), and HHHpp (3).

Ternary 3 He Process + 9 C s 9 B 540 eV 6 Be & 3 He 2 A GeV/c Carbon beam of a magnetic rigidity Z/A = 6/9 ( 12 C 9 C) was provided for emulsions to determine the probabilities 9 C 8 Bp (1), 7 Bерp (2), HeHepp (7), HeHHpp (5), HeHeHe (3).

3He Process: mixed isotope fusion + 11 C m 13 O 8.58 ms 6 Be & 4 He 12 N 11.0 ms + 14 O 70.6 s 15 O 122 s + 11 B 80.2 % CNO cycle 12 C % 7 Be 53.3 d 10 C 19.2 s 10 B 19.8% 14 O 70.6 s

Fragmentation of relativistic nuclei provides an excellent quantum laboratory to explore the transition of nuclei from the ground state to a gas-like phase composed of nucleons and few-nucleon clusters having no excited states, i. e. d, t, 3 He, and. The research challenge is to find indications for the formation of quasi-stable systems significantly exceeding the sizes of the fragments. Search for such states is of interest since they can play a role of intermediate states for a stellar nuclear fusion due to dramatically reduced Coulomb repulsion. The fragmentation features might assist one to disclose the scenarios of few-body fusions as processes inverse to fragmentation.

158 A GeV/c Pb

P A V I C O M Relativistic Nuclei in EmulsionFission Fragments in Films

11 N 1.58 MeV 12 O 0.4 MeV 15 F 1 MeV 13 N 10 min 20 Na 448 ms 20 Mg 95 ms Walking along proton stability line 12 N 11 ms 16 Ne MeV 14 N 99.6% 13 O 8.58 ms 14 O 70.6 s 15 O 122 s 16 O 99.8% 19 F 100% 20 Ne 90.48% 16 F 0.04 MeV 17 F 64.5 s 18 F 110 min 17 Ne 109 s 18 Ne 1.67 s 19 Ne 17.2 s

10 C 19.2 s 13 O 8.58 ms 16 Ne MeV Multifragmentation in H&He

12 O 0.4 MeV 9 C, ms 6 Be, MeV +12 MeV +16 MeV +38 MeV Multifragmentation in H&He

11 C m 14 O 70.6 s 17 Ne 109 s 20 Mg 95 ms Multifragmentation in H&He

6 Be 7 Be 8B8B 9C9C Pure 3 He Nucleus Clustering in Light Nuclei ?

Fragmentation of a 28 Si of the energy of 3.65A GeV in on an emulsion nucleus. On the upper photograph one can see the interaction vertex and the jet of fragments in a narrow cone along four accompanying single-charged particles in a wide cone and three fragments of the target-nucleus. Moving toward the fragment jet direction (upper photograph) it is possible to distinguish 3 Z=1 fragments and 5 Z=2 fragments. An intensive track on the upper photograph (the third one from above) is identified as a very narrow pair of Z=2 fragments corresponding to the 8 Be decay. A three-dimensional image of the event was reconstructed as a plane projection by means of an automated microscope (Lebedev Institute of Physics, Moscow) of the PAVIKOM complex.

A=6 =0.092 MeV

3.65A GeV 20 Ne Dissociation into charge state with 8 Be pair

4.5A GeV/c 28 Si Dissociation into charge state (narrow cone) with pair of 8 Be and triple 12 C * like fragments

4.5A GeV/c 6 Li

7 Li. About 7% of all inelastic interactions of 7 Li nuclei are white stars (80 events). Decay of 7 Li nucleus to - particle and triton - 40 events.

Relativistic 7 Be fragmentation: 2+2 The 7 Вe * 3 He decay is occured in 22 white stars with 2+2 topology. In the latter, 5 white stars are identified as the 7 Вe * (n) 3 He 3 He decay. Thus, a 3 He clustering is clearly demonstrated in dissociation of the 7 Be nucleus.