Investigation of neutron moderators with spherical voids
This is the web page connected to the bachelor project of Mads Bertelsen and Pia Jensen (now Pia Jensen Ray) from the Niels Bohr Instutute under the University of Copenhagen. Here it is possible to download the project, the source codes, and some of the figures from the project with larger quality. The download section is at the bottom of this page.
Introduction
The project was a study of moderator geometry, working with both theory, simulation and experiments. A simple simulation was written in order to model a box neutron moderator with a concave void, investigating the flux increase from the void, as compared to the flux from a similar flat box moderator. A gain of about 3.5 was found in both the experiments and the simulation, after addition of absorption in the simple model.
The sph1 moderator used during the experiment.
Regular downloads
Below is the report, all the source codes shown in the report, and the measurements taken during the experiment.
- Project report (handed in on 06.01.2011)
- Source codes: Simulation, analyser program, and MATLAB functions
- Measurements from the experiment
- Project report over later work
We have given speeches about the project several times, and the used slides can be downloaded from below (in order of appearances).
- ESS simulation group meeting (presented by Mads) (held on 11.01.2011)
- Defense of project (presented by Mads – slides unfortunately not available here) (held on 17.02.2011)
- Defense of project (presented by Pia) (held on 17.02.2011)
- ECNS conference talk (presented by Mads) (held on 19.07.2011)
Figure downloads
Below are first the most important figures to see in large resolution. Simply clicking the thumbnail brings you to the larger image. Note that there are links to these images in the table below as well (and to MATLAB FIG files for some of them).
Below are all the figures shown in the report (except the flow-charts), saved in high resolution PNG files. Some of the figures can also be downloaded as MATLAB FIG files, which are plots that can be opened in MATLAB and seen as if you plotted them yourself.
| Number | Description | Download link(s) |
|---|---|---|
| 2.1(a) | Scattering coordinate system definition | PNG |
| 2.1(b) | Rotation of scattering coordinate system | PNG |
| 2.2(a) | Distribution of theta | PNG |
| 2.2(b) | Distribution of alpha | PNG |
| 2.3 | Alpha as a function of theta and theta' | PNG |
| 2.4 | Illustration of the "source volume" | PNG |
| 2.5 | Illustration of the focus effect | PNG |
| 3.2(a) | Neutron intersecting void | PNG |
| 3.2(b) | Neutron ending in void | PNG |
| 3.3 | The mirror routine | PNG |
| 3.4(a) | Flux 1 mm over flat moderator | PNG / FIG |
| 3.4(b) | Flux 1 mm over sph2 moderator | PNG / FIG |
| 3.4(c) | Flux 1 mm over sph1 moderator | PNG / FIG |
| 3.4(d) | Flux 13 mm over flat moderator | PNG / FIG |
| 3.4(e) | Flux 13 mm over sph2 moderator | PNG / FIG |
| 3.4(f) | Flux 13 mm over sph1 moderator | PNG / FIG |
| 3.4(g) | Flux 25 mm over flat moderator | PNG / FIG |
| 3.4(h) | Flux 25 mm over sph2 moderator | PNG / FIG |
| 3.4(i) | Flux 25 mm over sph1 moderator | PNG / FIG |
| 3.4(j) | Flux 37 mm over flat moderator | PNG / FIG |
| 3.4(k) | Flux 37 mm over sph2 moderator | PNG / FIG |
| 3.4(l) | Flux 37 mm over sph1 moderator | PNG / FIG |
| 3.5(a) | Divergence diagram | PNG |
| 3.5(b) | Divergence calculation | PNG |
| 3.6(a) | Divergence of neutrons from sph1 void | PNG / FIG |
| 3.6(b) | Divergence of neutrons from sph2 void | PNG / FIG |
| 3.7(a) | r_old's from flat moderator | PNG / FIG |
| 3.7(b) | r_old's from sph1 moderator | PNG / FIG |
| 3.7(c) | r_old's from sph2 moderator | PNG / FIG |
| 4.1 | Moderator wood box | PNG |
| 4.2 | Neutron counter electronics | PNG |
| 4.3 | Measured data | PNG / FIG |
| 5.1 | Energy distribution from primary moderator | PNG |
| 5.2 | Measured data and simulated data | PNG / FIG |
| 5.3 | Neutron scalar flux for two cases | PNG |
| 5.4 | Measured data and simulated data w./w.o. abs. | PNG / FIG |
| F.1 | Neutron detector and housing | PNG |
| F.2(a) | Exact measurements of flat moderator | PNG |
| F.2(b) | Exact measurements of sph1 moderator | PNG |
| F.3 | Overview of radioactive source | PNG |
| G.1(a) | r_old's from flat moderator (more energies) | PNG / FIG |
| G.1(b) | r_old's from sph1 moderator (more energies) | PNG / FIG |
| G.1(c) | r_old's from sph2 moderator (more energies) | PNG / FIG |
| G.2(a) | Measured data and simulated data | PNG / FIG |
| G.2(b) | Measured data and thermal simulated data | PNG / FIG |
| G.2(c) | Measured data and simulated data w. absorption | PNG / FIG |
| G.3 | Overview of the Farnsworth-Hirsch fusor | PNG |
| G.4(a) | Typical short path of a neutron from the simulation | PNG |
| G.4(b) | Typical long path of a neutron from the simulation | PNG |
| H.2 | Scattering cross section data from NNDC | PNG |
Photographs from the experiments
Finally, during the project several photos were taken, to document all the fun we had. These are shown below with small explanations. For larger size images, simply click the thumbnails.
