Paper 
Title 
Page 
THPWO083 
Simulation of a Beam Rotation System for the SINQ Spallation Source at PSI 
3954 

 D. Reggiani, T. Reiss, M. Seidel, V. Talanov, M. Wohlmuther
PSI, Villigen PSI, Switzerland



With a nominal beam power of nearly 1 MW on target, the PSISINQ ranks among the world's most powerful neutron spallation sources. The proton beam transport to the SINQ target is carried out exclusively by means of linear elements. As a consequence, at the SINQ target entrance the beam presents Gaussian transverse x and y distributions with tails cut short by collimators. This leads to a highly uneven temperature distribution inside the SINQ zircaloy target, giving rise to thermal and mechanical stress. In view of a future beam intensity upgrade, the possibility of homogenizing the beam distribution by means of a fast beam rotation system is currently under study. Important aspects of this method concern the resulting neutron spectrum and flux distribution. The simulations of the beam distribution achievable thanks to this technique as well as its consequences in terms of neutron production are presented in this contribution.



THPWO084 
Optimization of a Bispectral Boxed SidebySide Moderator for the TargetModeratorReflector System of the ESS 
3957 

 T. Reiss, U. Filges, V. Talanov, M. Wohlmuther
PSI, Villigen PSI, Switzerland
 F. X. Gallmeier
ORNL, Oak Ridge, Tennessee, USA



Providing bispectral neutron beams is one of the main neutronics design criteria for the targetmoderatorreflector (TMR) system of the European Spallation Source, to be built in Lund (Sweden). As a first step, the requirements of neutronics instruments regarding the neutron spectrum are formulated, a figure of merit is defined. In order to maximize the moderator performance to obtain bispectral neutron extraction, a parametrized model of the TMR system is developed and used with a MCNPXbased optimization framework. This model is then used to study and optimize the moderator performance, especially in the thermal and cold parts of the spectrum. Results obtained with an optimized moderator setup are dicussed and compared with the requirements of the instruments.


