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

More documents

Recommendations

Info

5.1.2 Derivation from Fermi’s golden rule . . . . . . . . . . . . . . . . . . . . . 62 5.1.3 Derivation from the mean—field cranking formula . . . . . . . . . . . . . . 64 5.2 Results <strong>of</strong> the calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 5.2.1The adiabatic two-center shell model . . . . . . . . . . . . . . . . . . . . . 65 5.2.2 The diabatic two-center shell model . . . . . . . . . . . . . . . . . . . . . 71 6 Melting or transfer <strong>of</strong> nucleons in fusion? 81 6.1Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 7 The quasi-fission process in the DNS 94 7.1Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 8 Summary and outlook 105 8.1Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 8.2 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 08 A The two-center shell model (TCSM) 110 B The collective response function 116 5
Chapter 1 The elements existing in nature are ordered according to their atomic (chemical) properties in the periodic system which was developed by Mendeleev and Lothar Meyer. The heaviest element <strong>of</strong> natural origin is uranium. The transuranium elements range from neptunium (Z=93) via californium (Z=98) and fermium (Z=100) up to lawrencium (Z=103). For the heaviest systems the Coulomb repulsion between the increasing number <strong>of</strong> protons grows faster than the attractive nuclear forces. The heavy nuclear systems are macroscopically instable, their existence is determined by shell effects. Theoretical nuclear physicists ([1], [2]) predicted that so-called closed proton and neutron shells should counteract the repelling Coulomb forces. Atomic nuclei with these special ”magic” proton and neutron numbers and their neighbours could again be rather stable. These magic proton (Z) and neutron (N) numbers were thought to be Z=114, N=184 or 196. Studies <strong>of</strong> the shell structure <strong>of</strong> superheavy elements in the framework <strong>of</strong> the meson field theory and the Skyrme-Hartree-Fock approach have recently shown that the magic shells in the superheavy region are very dependent on isotopes [3]. According to these investigations, the region <strong>of</strong> maximum stability may be near Z=120 or Z=126. The synthesis <strong>of</strong> new nuclear species relies on the constituents <strong>of</strong> the premordial nuclei available in nature. The available nuclei are limited in their neutron-to-proton ratio by the beta decay and in size by charged-particle decay and fission due to the increasing electrostatic repulsion between the constituent protons. The first method used to produce transuranium elements, which is still used to synthesize larger quantities <strong>of</strong> specific isotopes <strong>of</strong> elements from neptunium to einsteinium, was the consecutive capture <strong>of</strong> neutrons by uranium isotopes and 6
Page 1 and 2: Effects of
Page 3: 1 Introduction 6 1.1 The DNS-concep
Page 7 and 8: observed the rapid fall-of<
Page 9 and 10: Figure 1-1 illustrates the compound
Page 11 and 12: smaller than the extra-extra push e
Page 13 and 14: fusion and quasi-fission processes
Page 15 and 16: In the present chapter we have pres
Page 17 and 18: higher collective velocities to rep
Page 19 and 20: 2.1 General considerations We want
Page 21 and 22: couplings. Diabatic basis states ψ
Page 23 and 24: Chapter 3 The synthesis of<
Page 25 and 26: is calculated within the TCSM using
Page 27 and 28: E adiab (MeV) n E diab (MeV) n 30 2
Page 29 and 30: E diab (MeV) n 60 55 50 45 40 100Mo
Page 31 and 32: 3-5: Diabatic potentials for the sy
Page 33 and 34: 3-7: The same as in Fig. 3-6 for th
Page 35 and 36: The estimated collective velocities
Page 37 and 38: 3-10: Diabatic contributions as a f
Page 39 and 40: effects give a justification for th
Page 41 and 42: The similarity of
Page 43 and 44: 4.1.3 Alternative microscopical met
Page 45 and 46: 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 and 98:
Y Z Y A 0,10 0,08 0,06 0,04 0,02 0,
Page 99 and 100:
estimated from the difference betwe
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
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?