JAEA-Conf 2011-002 - 日本原子力研究開発機構

JAEA-Conf 2011-002
Figure 4. Production of 3 He in the interaction of 120, 160 and 200 MeV protons with Au [18]. 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 Figure 5 we show comparison between light complex particles production from Fe at 175 MeV QMN [16]
with QMD model calculations (dashed line). Whereas proton production is described by QMD (not shown in the
picture), we observe that the calculations generally underestimate the experimental data for composite particles.
A similar deficiency is observed by Watanabe and Kadrev [15] in the comparison of QMD calculations with
angle-integrated energy-differential cross sections for the production of light complex particles at 96 MeV. To
provide a more realistic description of the dynamical processes, we assumed that light charged particles are
formed by successive coalescence starting from a leading nucleon, and that this process is occurring on the
surface of the pre-equilibrium nucleon-target compound. Watanabe and Kadrev modified the JQMD code to
include this surface coalescence model. This model is dependent on three adjustable parameters: a radius defining
the internal part of the nucleon-target compound, a distance defining the surface region and a phase-space
condition expressed in MeV c -1 fm -1 to verify is a cluster is formed. We performed our calculations applying to
the adjustable parameters the same values chosen by Watanabe and Kadrev as best fit for the 96 MeV data.
Preliminary calculations with the modified JQMD code including the surface coalescence model are presented in
Figure 5 (solid). We observe that production of triton, 3 He and α particle is described by the modified calculations.
Prediction of deuteron production is enhanced, however the calculations still underestimate the data. This
deficiency is larger at small emission angles, whereas we did not observe it at larger angles. The underestimation
in the production of deuteron with the modified JQMD calculations is also observed by Watanabe and Kadrev at
96 MeV. Other reaction processes as direct pick-up of a proton by an incident neutron may explain this
discrepancy.
Figure 5. Production of deuteron, triton, 3 He and α particle in the interaction of 175 MeV QMN with Fe[16]. Experimental
data at 20 o in the laboratory system are compared with default QMD calculations with the JQMD code (dashed line) and with
modified QMD calculations where a surface coalescence model was applied (solid line).