| 1. |
- Dian, Eszter, et al.
(författare)
-
Shielding optimization study for 10b-based large area neutron detectors with detailed geant4 model
- 2017
-
Ingår i: 2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop, NSS/MIC/RTSD 2016. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509016426
-
Konferensbidrag (refereegranskat)abstract
- The European Spallation Source (ESS) sets the scope on replacing 3He tube detectors where it is reasonably achievable, consequently advanced neutron detectors require a signal-To-noise (S/N) ratio high enough to be competitive with 3He tubes and satisfy scientific requirements. Advanced local shielding could provide the improved S/N. The objective of the current study is to create a tool that can be used during the shielding optimization process. The study is performed with Monte-Carlo simulations using a Geant4 version extended with NXSG4, that is capable to handle the crystal structure of specific materials, therefore the effects of neutron absorption, coherent and incoherent scattering were simulated. Validation of the extended Geant4 code, developed at ESS is also part of the current study by comparing the simulated results with analytical calculations. A detailed and realistic model of the state-of-The-Art Multi-Grid detector has been implemented, as it is almost the only prototype with published data on scattering effects. Simulations were performed for appropriate shielding materials with various monoenergetic neutron beams.A robust tool has been developed that could be effectively used to arise the S/N via optimizing the detector shielding for specific setups and requirements for all inelastic instruments.
|
|
| 2. |
- Dian, Eszter, et al.
(författare)
-
Validation of Detailed Geant4 Model for Thermal Neutron Scattering using the Results of Multi-Grid Detector Prototype Test at CNCS at SNS
- 2017
-
Ingår i: 2017 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC). - : IEEE. - 9781538622827
-
Konferensbidrag (refereegranskat)abstract
- The European Spallation Source (ESS) aspires to be the worlds leading neutron source of the upcoming decades, and sets the scope on replacing He-3 tube detectors where it is reasonably achievable. The Multi-Grid detector, an Ar/CO2-filled proportional chamber based on solid (B4C)-B-10 converter, is the most potent replacement technology for chopper spectroscopy. This study reproduces in a detailed Geant4 geometry of a neutron scattering instrument the data from the Multi-Grid demonstrator detector, that has been tested for a 1 year period, installed side-by-side to the He-3 tubes at the CNCS instrument at SNS. For the further understanding of the background of the detector, Monte-Carlo simulations were performed, with the ESS Coding Framework, using a Geant4 version extended with NXSG4 and NCrystal. A detailed and realistic model of the prototype was built and was validated via comparison against measured data. With this model, different sources of neutron scattering were determined and studied separately, providing a better understanding of the scattered neutron background. Due to these capabilities the model will be used in the further optimization of the detector, especially for the background reduction via shielding, which will lead to instruments with better signal-to-background ratio by design.
|
|
