The Physics of Spallation Processes

4.3. MODELING OF TRANSPORT PROCESSES 43energy difference in the entrance and exit channels. As a result the high energy emissionspectrum is much better described and the overall energy balance in the INC issignificantly improved.Many of the calculations performed in the current work for thin targets (interactionswithout secondary particle production) have been performed with the Liege INCL2.0model [Cug84, Cug87, Cug89, Cug89a, Cug92, Cug97a, Cug97b] combined to the statisticalevaporation code GEMINI [Cha88] (version 5/97).Unless stated otherwise in specific cases, in most simulation calculations discussed inthe following sections, the set of standard parameters listed in Tab. 4.1 was used. Thevarious code packages differ essentially by the choice of the parameters (cf. sect. 4.4),improvements implemented in the original models or because they include alternativespecifications or prescriptions.A list of INCE Event generators, latest state-of-the-art radiation transport code systemsfor spallation source design and applications, recent new models together with theauthors and references is given in Tab. 4.2.Table 4.1: Set of standard parameters for HERMES, LCS and MCNPX.basic assumptionsIntranuclear CascadeMonte Carlo techniquenuclear density distributionnuclear density depletionBertini INC [Ber63, Ber69, Ber70, Ber72]“space-like”ρ(r) = ρ 0 (exp((r − c)/a) + 1) −1c = 1.07A 1/3 fm, a = 0.545 fm, ρ 0 = 0.17Ze/A fm −3ρ(r) = α i ρ 0 ; α 1 = 0.9, α 2 = 0.2, α 3 = 0.01not consideredoptions chosen by the usercut off for switching INC/evap. 7 MeV (n), 7 MeV+Coulomb barrier (p)equilibrium stage Dresner model [Dre62] for n, p, d, t,3 He, 4 He emission+fission+γfission-evaporation model RAL[Atc89, Atc94]level density description HETC (cf. sect. 4.4.1)B0 parameterPb: a=A/10, W,Hg: a=A/8Coulomb barriers according to equation 4.12elastic scatteringswitched on for protons, neutronscut off energy for n transport HETC Ekin n > 20 MeV, MORSE/MCNP En kin ≤ 20 MeVcut off energy for p, π, µ transport 1, 0.149 and 0.113 MeV (only HETC)proton beampencil-beampre-equilibrium modeloffDetails are given in ref. [Clo88, Pra89, Hug97, Atc89, Atc94, Dre62, Fil00c].