Bachelor Project

Investigation of neutron moderators with spherical voids

This is the web page connected to the bachelor project of Mads Bertelsen and Pia Jensen 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.

Front page photo

The sph1 moderator used during the experiment.

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.



Regular downloads

Below is the report, in different file formats, all the source codes shown in the report, and the measurements taken during the experiment.

Description Download links
Project report PDF (1.50 MB), PS (42.4 MB), DVI (3.73 MB)
Source code: Simulation ZIP (16.0 KB)
Source code: Analyser program ZIP (8.89 KB)
Source code: MatLAB functions ZIP (15.4 KB)
Measurements from the experiment ZIP (1.51 KB)
Project report over later work PDF (580 KB)

We have given speeches about the project several times, and the used slides can be downloaded from below (in order of appearances).

Description Download links for slides
ESS simulation group meeting (11.01.2011) PDF (829 KB)
Defence of project (Mads) (17.02.2011) PDF ()
Defence of project (Pia) (17.02.2011) PDF (1.05 MB)
ECNS conference talk (Mads) (19.07.2011) PDF (6.79 MB)


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).

thumbnail

1 mm over flat

thumbnail

13 mm over flat

thumbnail

25 mm over flat

thumbnail

37 mm over flat

thumbnail

1 mm over sph2

thumbnail

13 mm over sph2

thumbnail

25 mm over sph2

thumbnail

37 mm over sph2

thumbnail

1 mm over sph1

thumbnail

13 mm over sph1

thumbnail

25 mm over sph1

thumbnail

37 mm over sph1

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 links
2.1(a) Scattering coordinate system definition PNG (64.2 KB)
2.1(b) Rotation of scattering coordinate system PNG (78.8 KB)
2.2(a) Distribution of theta PNG (35.5 KB)
2.2(b) Distribution of alpha PNG (64.3 KB)
2.3 Alpha as a function of theta and theta' PNG (39.4 KB)
2.4 Illustration of the "source volume" PNG (68.0 KB)
2.5 Illustration of the focus effect PNG (61.3 KB)
3.2(a) Neutron intersecting void PNG (30.0 KB)
3.2(b) Neutron ending in void PNG (32.1 KB)
3.3 The mirror routine PNG (23.1 KB)
3.4(a) Flux 1 mm over flat moderator PNG (786 KB), FIG (30.6 KB)
3.4(b) Flux 1 mm over sph2 moderator PNG (790 KB), FIG (31.4 KB)
3.4(c) Flux 1 mm over sph1 moderator PNG (806 KB), FIG (31.9 KB)
3.4(d) Flux 13 mm over flat moderator PNG (819 KB), FIG (37.4 KB)
3.4(e) Flux 13 mm over sph2 moderator PNG (814 KB), FIG (38.4 KB)
3.4(f) Flux 13 mm over sph1 moderator PNG (846 KB), FIG (39.3 KB)
3.4(g) Flux 25 mm over flat moderator PNG (839 KB), FIG (39.2 KB)
3.4(h) Flux 25 mm over sph2 moderator PNG (838 KB), FIG (40.2 KB)
3.4(i) Flux 25 mm over sph1 moderator PNG (871 KB), FIG (41.3 KB)
3.4(j) Flux 37 mm over flat moderator PNG (853 KB), FIG (39.6 KB)
3.4(k) Flux 37 mm over sph2 moderator PNG (861 KB), FIG (40.4 KB)
3.4(l) Flux 37 mm over sph1 moderator PNG (895 KB), FIG (41.7 KB)
3.5(a) Divergence diagram PNG (35.6 KB)
3.5(b) Divergence calculation PNG (62.9 KB)
3.6(a) Divergence of neutrons from sph1 void PNG (86.5 KB), FIG (10.0 KB)
3.6(b) Divergence of neutrons from sph2 void PNG (87.3 KB), FIG (10.0 KB)
3.7(a) r_old's from flat moderator PNG (210 KB), FIG (263 KB)
3.7(b) r_old's from sph1 moderator PNG (248 KB), FIG (272 KB)
3.7(c) r_old's from sph2 moderator PNG (230 KB), FIG (267 KB)
4.1 Moderator wood box PNG (94.0 KB)
4.2 Neutron counter electronics PNG (162 KB)
4.3 Measured data PNG (80.6 KB), FIG (12.8 KB)
5.1 Energy distribution from primary moderator PNG (90.6 KB)
5.2 Measured data and simulated data PNG (123 KB), FIG (20.4 KB)
5.3 Neutron scalar flux for two cases PNG (116 KB)
5.4 Measured data and simulated data w./w.o. abs. PNG (161 KB), FIG (28.7 KB)
F.1 Neutron detector and housing PNG (120 KB)
F.2(a) Exact measurements of flat moderator PNG (54.7 KB)
F.2(b) Exact measurements of sph1 moderator PNG (98.1 KB)
F.3 Overview of radioactive source PNG (219 KB)
G.1(a) r_old's from flat moderator (more energies) PNG (306 KB), FIG (228 KB)
G.1(b) r_old's from sph1 moderator (more energies) PNG (307 KB), FIG (226 KB)
G.1(c) r_old's from sph2 moderator (more energies) PNG (309 KB), FIG (227 KB)
G.2(a) Measured data and simulated data PNG (123 KB), FIG (20.4 KB)
G.2(b) Measured data and thermal simulated data PNG (125 KB), FIG (20.5 KB)
G.2(c) Measured data and simulated data w. absorption PNG (131 KB), FIG (20.4 KB)
G.3 Overview of the Farnsworth-Hirsch fusor PNG (146 KB)
G.4(a) Typical short path of a neutron from the simulation PNG (112 KB)
G.4(b) Typical long path of a neutron from the simulation PNG (124 KB)
H.2 Scattering cross section data from NNDC PNG (133 KB)


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.

photo

The paraffin wax for the moderators was melted over water bath.

photo

An image of the flat moderator.

photo

The void in the sph1 moderator was carved out by hand, using clay tools.

photo

View of the finalized sph1 moderator.

photo

The radioactive neutron source used for the experiment.

photo

A view inside the iron barrel of the neutron source. The aluminium tubes are visible.

photo

The detector and the used boron plastic housing.

photo

Measurements underway.