JAEA-Conf 2011-002 - 日本原子力研究開発機構

JAEA-Conf 2011-002
175 MeV QMN is compared with default TALYS calculations (solid line). In the pre-equilibrium region the
dominant emission mechanism in the TALYS code is the direct pick-up of one or more nucleons; in the case of α
particles is also present the concurrent knock-out of preformed clusters. TALYS computes these mechanisms
according to the Kalbach systematics [11]. The model proposed by Kalbach is based on proton-induced
experimental data with energies up to 90 MeV, and neutron-induced experimental data up to 63 MeV. However
TALYS extends tout-court the Kalbach systematics to higher incident energies, up to 200 MeV.
Figure 1. Production of deuteron, triton, 3 He and α particle in the interaction of 175 MeV QMN with Bi [16]. Experimental
data at 20 o in the laboratory system are compared with default TALYS calculations (solid line) and with TALYS calculations
modified reducing the Kalbach contribution to the pre-equilibrium emission (dashed line).
Preliminary data by Bevilacqua et al. [16] are the first neutron-induced DDX for production of light complex
particles available in the 100 to 200 MeV region, however several proton-induced data are present in literature in
this energy interval. We compared TALYS calculations with proton-induced production of light complex
particles and we observed the same overestimation seen in the comparison with neutron-induced data. In Figure 2
we present production of light complex particles in the interaction of 175 MeV protons with Ni [17]; default
TALYS calculations (solid line) overestimate pre-equilibrium production of all the light complex particles.
Calculations without the contribution of the direct-like mechanisms described by Kalbach show large
underestimation of the experimental data. Our preliminary results show that the NT and KO mechanisms should
be included, but that the energy dependence described by Kalbach needs to be corrected for higher incident
energies. We observed that reducing the NT and KO (only α particle) contribution to the pre-equilibrium
emission provides a better description of the experimental data for incident energies above 90 MeV. In Figure 2
we present, as an example, TALYS calculations with different values of the Cstrip parameter (overall
multiplication factor for the NT mechanism); we observe that scaling the NT contribution down to 25% of its
default value improves the fitting of the experimental data at 20 o in the laboratory system.
Figure 2. Production of deuteron, triton, 3 He and α particle in the interaction of 175 MeV protons with Ni [17]. Experimental
data at 20 o in the laboratory system are compared with default TALYS calculations (solid line) and with TALYS calculations
modified reducing the Kalbach contribution to the pre-equilibrium emission. The NT contribution (Cstrip parameter) has been
scaled by a factor 0.75, 0.50, 0.25 and 0.10. “Cstrip 0.” line represents TALYS calculations without NT contribution. In the
case of α particle production, we plotted also TALYS calculations without NT and KO (“Cstrip/Cknock 0.” line).