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The Radiological Footprint of a Be-based Neutron Source

Koufigar, Sharareh LU (2015) FYSK01 20151
Department of Physics
Nuclear physics
Abstract
The radiological footprint of a Be-based neutron source embedded within the Aquarium of the Source-Testing Facility (STF) at the Division of Nuclear Physics at Lund University will soon be carefully mapped. As a precursor to this measurement program, neutron and gamma-ray energy spectra at beamport apertures have been measured using 3He and LaBr3(Ce) (cerium-activated lanthanum bromide) detectors. The measured energy spectra and rates will provide crucial benchmarks for ongoing efforts to simulate the neutron and gamma-ray fields associated with the source. The ultimate goal of the project is the development of a software toolkit which precisely replicates the radiological environment provided by the source. This toolkit will greatly... (More)
The radiological footprint of a Be-based neutron source embedded within the Aquarium of the Source-Testing Facility (STF) at the Division of Nuclear Physics at Lund University will soon be carefully mapped. As a precursor to this measurement program, neutron and gamma-ray energy spectra at beamport apertures have been measured using 3He and LaBr3(Ce) (cerium-activated lanthanum bromide) detectors. The measured energy spectra and rates will provide crucial benchmarks for ongoing efforts to simulate the neutron and gamma-ray fields associated with the source. The ultimate goal of the project is the development of a software toolkit which precisely replicates the radiological environment provided by the source. This toolkit will greatly facilitate the interpretation of detector-development and shielding studies performed at the STF. (Less)
Popular Abstract
An atomic nucleus consists of protons and neutrons (nucleons) which are
held together by two forces that counterbalance each other. These two forces
are known as the strong force and the Coulomb force. The very attractive strong
force acts between all nucleons over a separation distance of about 1 fm. The
repulsive Coulomb force acts between all protons over an infinite separation
distance. A stable system of many protons and neutrons (an atomic nucleus)
can result if the attractive strong force between the nucleons overcomes the
repulsive Coulomb force of the protons. As an illustration of the importance of
the neutron to matter, for most atomic nuclei, there are more (often far more)
neutrons than protons present in the nucleus.... (More)
An atomic nucleus consists of protons and neutrons (nucleons) which are
held together by two forces that counterbalance each other. These two forces
are known as the strong force and the Coulomb force. The very attractive strong
force acts between all nucleons over a separation distance of about 1 fm. The
repulsive Coulomb force acts between all protons over an infinite separation
distance. A stable system of many protons and neutrons (an atomic nucleus)
can result if the attractive strong force between the nucleons overcomes the
repulsive Coulomb force of the protons. As an illustration of the importance of
the neutron to matter, for most atomic nuclei, there are more (often far more)
neutrons than protons present in the nucleus. Neutrons are thus crucial to the
existence of the elements as we know them.
While neutrons that are bound within an atomic nucleus are stable, neutrons
that are outside of the atomic nucleus (free neutrons) are unstable with a mean
life time of about 15 minutes. They become protons via beta decay with a mean
lifetime of about 15 minutes. Due to their lack of charge, free neutrons are useful
probes of matter as they penetrate deeply. Due to their mass, which is essentially
the same as the mass of the proton, they are particularly useful for probing
hydrogen-rich materials. Free neutrons are used in many diverse applications
from imaging, to diagnostic tools, to homeland security. Free neutrons originate
from many different processes. Environmental free neutrons are produced when
cosmic rays interact with the upper atmosphere. Neutrons are also freed by
nuclear reactors, particle accelerators, and radioactive sources. Radioactive
sources have by far the lowest cost per neutron, making them very attractive
for such studies. Two types of radioactive sources which produce free neutrons
are spontaneous fission sources and beryllium-based sources.
Be-based neutron sources will be employed at the Source-Testing Facility
(STF) at the Division of Nuclear Physics at Lund University for neutron-
detector development and studies of radiation shielding. Prior to the use of these
Be-based sources, their radiological footprint must first be carefully mapped.
This mapping is of course necessary for radiation-safety considerations, but also
to provide fundamentals benchmarks to users of the facility for ongoing efforts
to precisely simulate the radiated neutron and background gamma-ray fields.
Knowledge of the radiated fields will allow for normalization of the experimental
results.
This thesis reports these first benchmark measurements of neutron and
gamma-ray energy spectra at the STF obtained using 3He neutron and cerium-activated lanthanum bromide (LaBr3(Ce)) gamma-ray detectors. (Less)
Please use this url to cite or link to this publication:
author
Koufigar, Sharareh LU
supervisor
organization
course
FYSK01 20151
year
type
M2 - Bachelor Degree
subject
language
English
id
8083315
date added to LUP
2015-12-11 11:53:20
date last changed
2015-12-11 11:53:20
@misc{8083315,
  abstract     = {The radiological footprint of a Be-based neutron source embedded within the Aquarium of the Source-Testing Facility (STF) at the Division of Nuclear Physics at Lund University will soon be carefully mapped. As a precursor to this measurement program, neutron and gamma-ray energy spectra at beamport apertures have been measured using 3He and LaBr3(Ce) (cerium-activated lanthanum bromide) detectors. The measured energy spectra and rates will provide crucial benchmarks for ongoing efforts to simulate the neutron and gamma-ray fields associated with the source. The ultimate goal of the project is the development of a software toolkit which precisely replicates the radiological environment provided by the source. This toolkit will greatly facilitate the interpretation of detector-development and shielding studies performed at the STF.},
  author       = {Koufigar, Sharareh},
  language     = {eng},
  note         = {Student Paper},
  title        = {The Radiological Footprint of a Be-based Neutron Source},
  year         = {2015},
}