Incomplete vs. Complete Fusion at E/A ≈ 4–7 MeV

With a view to study onset and strength of incomplete fusion at low projectile energies (i.e., ~ 4–7 MeV/nucleon) three sets of experiments have been performed in 12C,16O+169Tm systems. In first set of experiments, spin-distributions and feeding intensity profiles for xn,αxn/2αxn-channels have been measured to figure out associated ℓ-values. The spin-distributions for direct-α-emitting channels (associated with incomplete fusion) have been found to be distinctly different than that observed for fusion-evaporation (complete fusion) channels. The mean value of driving input angular momenta associated with direct-α-emitting-channels have been found to be higher than that observed for fusion-evaporation xn/α-emitting-channels, and increases with direct-α-multiplicity in forward cone. The second set of experiments has been performed to understand influence of incomplete fusion on complete fusion at these energies. Incomplete fusion strength function has been deduced from the analysis of experimental excitation functions. The third set of experiments deals with the validation of data reduction procedure used to deduce incomplete fusion fraction, and to confirm the fusion incompleteness at slightly above barrier energies. Forward-recoil-ranges of heavy reaction products have been measured and analysed on the basis of break-up fusion model. More than one linear-momentum-transfer components associated with full- and/or partial-fusion of projectile with target nucleus have been observed. Experimental ranges of forward-recoils are found to be in good agreement with that estimated using range-energy formulation. The relative strengths of complete and incomplete fusion components deduced from the analysis of forward-recoil-ranges and excitation functions complement each other. Result presented in this paper conclusively demonstrate substantial incomplete fusion contribution at energy as low as 7% above the barrier.

[1]  Rakesh Kumar,et al.  Energy dependence of incomplete fusion processes in the {sup 16}O+{sup 181}Ta system: Measurement and analysis of forward-recoil-range distributions at E{sub lab}<=7 MeV/nucleon , 2010 .

[2]  A. Diaz-Torres.  Modelling incomplete fusion dynamics of weakly bound nuclei at near-barrier energies , 2010, 1003.5614.

[3]  R. Kumar,et al.  Role of high l values in the onset of incomplete fusion , 2009 .

[4]  R. Kumar,et al.  Disentangling full and partial linear momentum transfer events in the {sup 16}O+{sup 169}Tm system at E{sub proj}{<=}5.4 MeV/nucleon , 2009 .

[5]  Rakesh Kumar,et al.  Probing of incomplete fusion dynamics by spin-distribution measurement , 2009 .

[6]  M. Dasgupta,et al.  Suppression of complete fusion due to breakup in the reactions $^{10,11}$B + $^{209}$Bi , 2008, 0811.3891.

[7]  Rakesh Kumar,et al.  Observation of large incomplete fusion in 16O + 103Rh system at ≈3–5 MeV/nucleon , 2008 .

[8]  R. Kumar,et al.  Spin-distribution measurement: A sensitive probe for incomplete fusion dynamics , 2008 .

[9]  Rakesh Kumar,et al.  Influence of incomplete fusion on complete fusion: Observation of a large incomplete fusion fraction at E ≈ 5 − 7 MeV/nucleon , 2008 .

[10]  Rakesh Kumar,et al.  Observation of complete- and incomplete-fusion components in 159Tb , 169Tm ( 16O , x) reactions: Measurement and analysis of forward recoil ranges at E/A ≈ 5-6 MeV , 2007 .

[11]  M. Dasgupta,et al.  Relating breakup and incomplete fusion of weakly bound nuclei through a classical trajectory model with stochastic breakup. , 2007, Physical review letters.

[12]  M. Dasgupta,et al.  Isomer ratio measurements as a probe of the dynamics of breakup and incomplete fusion , 2006 .

[13]  A. J. Pacheco,et al.  Comprehensive study of reaction mechanisms for the Be9+Sm144 system at near- and sub-barrier energies , 2006 .

[14]  A. J. Pacheco,et al.  Fusion, reaction and break-up cross sections of weakly bound projectiles on 64Zn , 2004 .

[15]  S. Connell,et al.  Incomplete fusion of projectile fragments in the interaction of12C with103Rh up to 33 MeV per nucleon , 2004 .

[16]  E. Gadioli,et al.  Introductory Nuclear Physics , 1997 .

[17]  W. Galster,et al.  Study of the reaction mechanism of incomplete fusion with the reactions40Ar+11B,12,13C at 7 MeV/amu , 1986 .

[18]  Garg,et al.  Gamma-ray multiplicity distribution associated with massive transfer. , 1985, Physical review. C, Nuclear physics.

[19]  O. Hansen,et al.  Dynamics of Incomplete Fusion Reactions from γ -Ray Circular-Polarization Measurements , 1984 .

[20]  W. Galster,et al.  Influence of the mass asymmetry on the onset of incomplete and the limit to complete fusion , 1984 .

[21]  H. Lehr,et al.  Formation and decay of the compound nucleus studied in the reaction20Ne+27Al , 1983 .

[22]  C. Gerschel.  Incomplete fusion reactions , 1982 .

[23]  R. Janssens,et al.  Binary l-matched reactions in 14N + 159Tb collisions , 1982 .

[24]  T. Udagawa,et al.  Breakup-fusion description of massive transfer reactions with emission of fast light particles , 1980 .

[25]  R. Janssens,et al.  INCOMPLETE-FUSION REACTIONS IN THE N-14+TB-159 SYSTEM AND A SUM-RULE MODEL FOR FUSION AND INCOMPLETE-FUSION REACTIONS , 1980 .

[26]  A. Karvinen,et al.  Promptly emitted particles in nuclear collisions , 1980 .

[27]  R. Siemssen,et al.  INCOMPLETE FUSION IN C-12+GD-160 COLLISIONS INTERPRETED IN TERMS OF A GENERALIZED CONCEPT OF CRITICAL ANGULAR-MOMENTUM , 1979 .

[28]  H. Utsunomiya,et al.  Multiplicity of γ-rays following fast alpha;-particle emission in the 95 MeV 14N + 159Tb reaction , 1979 .

[29]  H. Hiruta,et al.  Gamma-rays from an incomplete fusion reaction induced by 95 MeV 14N , 1977 .

[30]  D. Guerreau,et al.  Study of charged particles emitted fromTe117compound nuclei. II. Comparison betweenAr40+Se77andN14+Rh103reactions and determination of critical angular momenta , 1974 .

[31]  H. Britt,et al.  ALPHA PARTICLES AND PROTONS EMITTED IN THE BOMBARDMENT OF Au$sup 197$ AND Bi$sup 209$ BY C$sup 12$, N$sup 14$, AND O$sup 16$ PROJECTILES , 1961 .