Topology of multifragmentation of light relativistic nuclei by P. I. Zarubin, JINROn behalf of the BECQUEREL CollaborationAll this and more on the Web sitehttp://becquerel.lhe.jinr.ru

Since 1970A.M. BaldinRelativistic Nuclear PhysicsLi

Mg-Si Dissociation into charge state 2+2+2+2+2+15 +proton

Advanced Composition ExplorerCosmic Ray Isotope Spectrometer Radioactive Clock isotopes Abundances of Iron, Cobalt, and Nickel Isotopes 1

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

Are you Boromean too?A=6=0.092 MeV

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

4.5 A GeV/c 16O Coherent Dissociation(PAVICOM image)

4.5A GeV/c 16O Coherent Dissociation with 8Be like fragmentationThe reliable observation of charged relativistic fragments is a motivation to apply emulsion technique (0.5 micron resolution). Requirements of conservation of the electric charge and mass number of a projectile fragments are employed in the analysis. Measurements of multiple scattering angles make it possible to estimate the total momentum of hydrogen and helium projectile fragments and thereby to determine their mass.

4.5A GeV/c 20Ne Peripheral Dissociation into charge state2+2+2+2+2 with 8Be like fragments

4.5A GeV/c 24Mg Peripheral Dissociation into charge state2+2+2+2+2+2 with 8Be and 12C* like fragments

4.5A GeV/c 28Si Dissociation into charge state 2+2+2+2+2+2+1 (narrow cone) with pair of 8Be and triple 12C* like fragments

The common topological feature for fragmentation of the Ne, Mg, and Si nuclei consists in a suppression of binary splitting 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.

dN/dTn

Tn=(M*n - n M )/(4 n ), MeV 0

0.81.62.44.5A GeV/c12C:=0.4 MeV 22Ne5 24Mg5 +3He

Alpha-particle condensation in nuclei P. Schuck, H. Horiuchi, G. Ropke, A. Tohsaki, C. R. Physique 4 (2003) 537-540

At least light n-nuclei may show around the threshold for n disintegration, bound or resonant which are of the -particle gas type, i. e., they can be characterized by a self-bound dilute gas of almost unperturbed -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 -particle structure in its ground state is 8Be. Other n-nuclei collapse in their ground states to much denser system where the -particles strongly overlap and probably loose almost totally their identity. When these n-nuclei are expanded, at some low densities -particles reappear forming a Bose condensate. If energy is just right, the decompression may stall around the -condensate density and the whole system may decay into -particles via the coherent state.12C3 , .,40Ca10 , 48Cr3 16O, 32S16O+4

Deuteron-Alpha Clustering in Light Nuclei10B(19.9%)6Li(7.5%)14N(99.634%)50V(0.25%)d

+4.5A GeV/c 6Li Coherent Dissociation (PAVICOM image)

6Li

1A GeV 10B Coherent Dissociation Into 2+2+1

In 65% of such peripheral interactions the 10B nucleus is disintegrated to two double charged and a one single-charged particles. A single-charged particle is the deuteron in 40% of these events and (2He+d)/(2He+p) 1 like in case of 6Li.

10B Fragmentation Topology

Fragment ChargeEvents with Q=5No mesons%White Stars%543211----4400-1--12213--11-1011512---2160653073---131516512----52200Total9341

4.5A GeV/c 14N Coherent Dissociation with 8Be like fragmentationd/p 14N nucleus, like the deuteron, 6Li and 10B belong to a rare class of even-even stable nuclei. It is interesting to establish the presence of deuteron clustering in relativistic 14N fragmentation.

14N dissociation accompanied by 8Be like pair3 afterproton

1.3A GeV 9Be dissociation in 2+2.10B9Be, Nuclotron, 2004.white starwith recoil protonwith heavy fragment of target nucleus

1A GeV 10B Fragmentation to 8B(PAVICOM image)

Triton-Alpha Clustering in Light Nuclei11B7Li7Li clustering. About 7% of all inelastic interactions of 7Li nuclei are peripheral interactions (80 events), which contain only the charged fragments of a relativistic nucleus. Half of these events are attributed to a decay of 7Li nucleus to -particle and a triton(40 events). The number of decays accompanied by deuterons makes up 30%, and by protons 20%. The isotopic composition points to the fact that these events are related to the dissociating structure of -particle and the triton clusters. 11B clustering. Analysis is in progress now.

7Li 92.5 %

7Be 53.3 d

8B 0.769 s

10B 19.8%

11B 80.2 %

12C 98.89 %

11C 20.38 m 12N 11.0 ms

9Be 100% 9C 0.1265 s

10C 19.2 s

8Be 6.8 eV9B 540 eV6Li 7.5 %Ground states lowest excitations

7Be, stable 8B, 770 ms 9C, 126.5 ms 6Be, 0.092 MeV 7B, 1.4 MeV 8C, 0.23 MeV 6e pp4He-1.372 MeV

8 pp6Be-2.14 MeV

7B p6e-2.21 MeV

6e 3He3He+11.48 MeVCrossing proton stability frontier

1.2A GeV 7Be dissociation in emulsion. Upper photo: splitting to two He fragments with production of two target-nucleus fragments. Below: white stars with splitting to 2 He, 1 He and 2 H, 1 Li and 1 H, and 4H fragments.

7Be Fragmentation Topology

Fragment ChargeWhite Stars%321-123851-2-28371-179--423Total75

Relativistic 7Be fragmentation: 2+2The 7e*3He decay is occured in 22 white stars with 2+2 topology. In the latter, 5 white stars are identified as the 7e*(n) 3He3He decay. Thus, a 3He clustering is clearly demonstrated in dissociation of the 7Be nucleus.

Triple He Process: pure isotope fusionTriple 3He process: 2 4He & 15.88 MeV at the output

+ 9C 0.1265 s9B 540 eV13O 8.58 ms12O 0.4 MeV6Be & 3HeThe fusion 3He3He3He6Be3He9 is one more option of the 3He process. In the 98C fragmentation, a crossing of the boundary of proton stability takes place. In this case, there arises a possibility in studying nuclear resonances by means of multiple 8C pppp4He and 8C pp3He3He decay channels, which possess a striking signature. It is quite possible that the study of these resonances would promote further development of the physics of loosely bound nuclear systems.12C nuclei with momentum 2.0 GeV/c per nucleon and intensity of about 109nuclei per cycle were accelerated at the JINR nuclotron and a beam of secondary nuclei with a magnetic rigidity corresponding to the ratio Z/A=6/9 was formed. The information obtained was used to analyze 9C nucleus interactions in emulsion.

3He Process: mixed isotope fusionEnergy release: 16.59 MeV

+ 11C 20.38 m

13O 8.58 ms6Be & 4He12N 11.0 ms+14O 70.6 s15O 122 s+11B 80.2 %CNO cycle12C 98.89 %7Be 53.3 d10C 19.2 s10B 19.8%14O 70.6 sEnergy release: 9.13 MeV

11N 1.58 MeV12O 0.4 MeV15F 1 MeV13N 10 min20Na 448 ms 20Mg 95 msWalking along proton stability line12N 11 ms16Ne 0.122 MeV14N 99.6%13O 8.58 ms14O 70.6 s15O 122 s16O 99.8%19F 100%20Ne 90.48%16F 0.04 MeV17F 64.5 s18F 110 min17Ne 109 s18Ne 1.67 s19Ne 17.2 s

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

Clustering in Light Nuclei

t

3He

6Li

7Li

6He

7Be

8B

12C

10B

12N

_1066906144.doc

10B

11B

11C

9Be

10C

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, 3He, and . The research challenge is to find indications for the formation of quasi-stable or loosely bound systems significantly exceeding the sizes of the fragments. Search for such states on the nuclear scale is of undoubted interest since they can play a role of intermediate states ("waiting stations") 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.