Effects of diabaticity on fusion of heavy nuclei in the dinuclear model ...

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Y Z Y A 0,10 0,08 0,06 0,04 0,02 0,00 0 0,10 10 20 Z 30 40 50 60 0,08 0,06 0,04 0,02 48Ca + 244Pu th. exp. 0,00 0 20 40 60 80 100 120 140 A 292114 7-2: The same as in Fig. 7-1for the hot fusion reaction Figure 48 + Ca 244 Pu→ 292 The 114. mass distribution (open points) is taken from the Ref. [11]. The excitation energy experimental <strong>of</strong> the initial DNS is E ∗ =10MeV (upper and lower parts). 99
estimated from the difference between the bombarding energy Ec.m. in the system <strong>of</strong> the center <strong>of</strong> mass and the value <strong>of</strong> the nucleus-nucleus potential for R corresponding to the bottom <strong>of</strong> the pocket for the initial configuration <strong>of</strong> the DNS. The charge (mass) quasi-fission distributions slightly on the excitation energy E depend ∗ the initial DNS (Fig. 7-1). This is due to the <strong>of</strong> dependence <strong>of</strong> the transport coefficients ∆ weak (±) the temperature [33]. With an increasing on temperature <strong>of</strong> the system, the influence <strong>of</strong> the shell effects on the process <strong>of</strong> nucleon transfer decreases more slowly than the exponential decrease <strong>of</strong> the shell correction in the potential energy [33]. It was experimentally found [113] in the quasifission reactions 238 U+ 16 O, 26 Mg, 27 Al, 32 S, 35 Cl, 40,48 Ca and nat Zn at several bombarding energies, that the mass asymmetry motion is dominated by the one-body dissipation which is independent <strong>of</strong> temperature. The observed relaxation times for the mass asymmetry mode <strong>of</strong> all the systems considered were in agreement with the wall dissipation picture [113]. Z Fig. 7-3 shows the quasi-fission charge and mass distributions for the cold fusion reactions with the projectiles 50 Ti, 64 Ni and 76 Ge on the target 208 Pb, which lead to the synthesis <strong>of</strong> the elements 258 104, 272 110 and 284 114, respectively, with an excitation energy about 11-16 MeV [7, 8]. The ratio between the drifts <strong>of</strong> mass and charge toward symmetric configurations <strong>of</strong> the DNS and toward more asymmetric ones becomes considerably larger with the increase <strong>of</strong> the charge number <strong>of</strong> the superheavy element. Due to this fact, the complete fusion probability in the mass asymmetry degree <strong>of</strong> freedom decreases from the nucleus 258 104 to 272 110. For the reaction 76 Ge+ 208 Pb→ 284 114, we found that the quasi-fission products are practically associated with fragmentations near the initial DNS due to small values <strong>of</strong> quasi-fission barriers B qf. Comparing Fig. 7-3 with Fig.7-2, we see that the mass and charge yields <strong>of</strong> the quasi-fission products for nearly symmetric configurations <strong>of</strong> the DNS are larger for the hot fusion reaction 48 Ca+ 244 Pu than for the cold fusion reaction 76 Ge+ 208 Pb. The quasi-fission barrier B qf <strong>of</strong> the initial DNS becomes larger with decreasing Z, and the nucleon transfer plays a larger role in the evolution <strong>of</strong> this DNS than the decay process. This is consistent with the conclusion that the hot fusion reaction 48 Ca+ 244 Pu→ 292 114 is preferable for the synthesis <strong>of</strong> the element 114, although the survival probability <strong>of</strong> the compound nucleus decreases with increasing excitation energy [20, 22]. In the cold fusion reactions, the quasi-fission is an important factor decreasing the complete fusion cross sections with increasing atomic number <strong>of</strong> the superheavy element. Producing the 100
Page 1 and 2:
Effects of
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1 Introduction 6 1.1 The DNS-concep
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Chapter 1 The elements existing in
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observed the rapid fall-of<
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Figure 1-1 illustrates the compound
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smaller than the extra-extra push e
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fusion and quasi-fission processes
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In the present chapter we have pres
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higher collective velocities to rep
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2.1 General considerations We want
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couplings. Diabatic basis states ψ
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Chapter 3 The synthesis of<
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is calculated within the TCSM using
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E adiab (MeV) n E diab (MeV) n 30 2
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E diab (MeV) n 60 55 50 45 40 100Mo
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3-5: Diabatic potentials for the sy
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3-7: The same as in Fig. 3-6 for th
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The estimated collective velocities
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3-10: Diabatic contributions as a f
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effects give a justification for th
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The similarity of
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4.1.3 Alternative microscopical met
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to the DNS concept [18, 34], cross
Page 47 and 48: U (MeV) 28 27 26 25 24 23 22 21 20
Page 49 and 50: U (MeV) 35 30 25 20 15 10 90Zr + 12
Page 51 and 52: 4-1: Fusion barriers B Table TCSM
Page 53 and 54: U (MeV) 40 30 20 10 20 10 0 a) b) 9
Page 55 and 56: experimental separation energy allo
Page 57 and 58: means a neglect of
Page 59 and 60: the case of an ind
Page 61 and 62: single particle density matrix exte
Page 63 and 64: following ratio in the limit <stron
Page 65 and 66: 5-1: Dependence of
Page 67 and 68: the microscopical mass parameter <s
Page 69 and 70: 5-3: Mass parameter Mεε as a func
Page 71 and 72: 5-4: Mass parameter Mεε as a func
Page 73 and 74: the approximate expressions (Eqs. (
Page 75 and 76: (10 3 m fm 2) M , M λλ εε 25 20
Page 77 and 78: (10 3 m fm 2) M εε M (10 λλ 4 m
Page 79 and 80: ~ f k (MeV -1) 0,20 0,15 0,10 0,05
Page 81 and 82: V (MeV) 30 25 20 15 10 5 0 -5 -10 1
Page 83 and 84: to the dependence of</stron
Page 85 and 86: where the lifetime t 0 of</
Page 87 and 88: 6-2: a) Time-dependent dynamical po
Page 89 and 90: Table 6-1: Quasi-fission and inner
Page 91 and 92: 6-3: Time-dependent average width <
Page 93 and 94: Chapter 7 In the quasi-fission proc
Page 95 and 96: The value of t0 is
Page 97: Y Z Y A 0,10 0,08 0,06 0,04 0,02 0,
Page 101 and 102: elements from Z=104 to Z=112 in the
Page 103 and 104: fission process is an important fac
Page 105 and 106: the neck coordinate ε and
Page 107 and 108: • The time-dependent transition b
Page 109 and 110: Appendix A For describing nucleus-n
Page 111 and 112: where The volume is V0 = 1 2 m0ϖ 2
Page 113 and 114: ϕ nz(z) = ⎧ ⎪⎨ ⎪⎩ C−1
Page 115 and 116: Appendix B The collective response
Page 117 and 118: [1] S.G.Nilsson et al., Phys. Lett.
Page 119 and 120: [27] N.V.Antonenko et al., in 1 st
Page 121 and 122: [63] Yu.F.Smirnov and Yu.M.Tchuvil
Page 123 and 124: [97] H. Hofmann et
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Effects of diabaticity on fusion of heavy nuclei in the dinuclear model ...

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