Doctorate in Applied and Engineering Physics  

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Thesis Proposal for the

Doctorate Program in Applied and Engineering Physics (DAEPHYS)

Starting in the Academic Year 2016/2017


Proposal 022


Title:New methods for radon detection and survey
 
Objectives (recommended length: 2000-3000 char):
Radiation dose due to Rn-222 represents more than 50% of the annual dose equivalent received by the general population. Rn-222 is abundant in granitic areas, such as the city of Guarda at the northeast of Portugal. This gas is recognized as a carcinogenic agent, being appointed by the World Health Organization as the second leading cause of lung cancer after tobacco smoke. Therefore, the knowledge of radon concentrations inside buildings is important from the point of view of radiological protection.
Thus, great effort has been dedicated to develop instruments for the measurement of radon and its decay products, either by alpha particle detection or gamma detection. Pin silicon photodiodes, have been used in alpha real-time spectroscopy acquisition using electrostatic capture of Rn-222 daughter nuclides. The same principle can be used with other detection types, like scintillator detector, provide the detection surface is placed at a high-voltage. Large area alpha detectors can than be build, allowing the efficient monitoring of low radon concentrations. We propose to build alpha-particle detectors and associate acquisition electronics to monitor radon Rn-222 and radon daughter nuclides. With this detectors real-time radon data can be obtained allowing the study of time-dependence radon concentration in several indoor locations.
 
Framework (recommended length: 500-2000 char):
The work will start by building a pin-photodiode based alpha-particle detector. This type of detector is document in literature and its behavior is understood. In this way it will serve as reference for future comparisons. The work will proceed by developing and studying a large area scintillation detector for alpha-particle spectroscopy. The detector will rely on electrostatic capture for better alpha-particle energy resolution and detection efficiency. Strategies to cover the scintillator with a thin conductive layer must be developed within the framework of the project. Scintillator low-cost light detection is also a topic that must be addressed. A comparison study between the performance of pin-photodiode and scintillation detector will be made. Radon and radon daughters collection depends on temperature and humidity. A study of collection efficiency dependence on this variables should be carried out. For a detection system, capable of standalone operation, dedicated software should be developed, preferably based on commercially available modules.

Gamma spectroscopy of radon progeny is less dependent on environmental variables and can give an accurate view of radon concentration in closed space. A comparison study between time-dependent gamma data and alpha data collected in the same confined volume should be made in order to benchmark the detector performance.

A number of prototypes will then be build and deployed in selected public buildings (schools, libraries, etc), with the goal to measure time-dependent radon fluctuations in those places. Time series analysis methods will be applied to summarize the collected data, to assess the degree of similarity of the signals collected in different locations and to examine the role of meteorological parameters on the temporal variability of radon and its progeny in indoor environments.
 
Tasks (recommended length: 1000-3000 char):
1. Construction and characterization of a pin-photodiode based alpha-particle detector.
2. Construction and characterization of a scintillator based alpha-particle detector.
3. Performance inter-comparison of both detector types.
4. Study of temperature/humidity dependence of detection efficiency for both detector types.
5. Development of standalone acquisition electronics.
6. Comparison between time-evolution alpha-particle data and gamma data in laboratory.
7. Deployment of develop detection system in selected public buildings (schools, libraries, etc)
8. Analysis of time series.
 
Research centre/lab or R&D unit hosting the thesis project:
LIP- Laboratório de Instrumentação e Física Experimental de Partículas
 
University to which the thesis project will be presented:
FC/UL - Faculdade de Ciências, Universidade de Lisboa
 
DAEPHYS Scientific Domain in which the project fits:
Radiation, nuclear and atomic techniques
 
Relation of the project to the Scientific Domains of DAEPHYS:
The project aims on the development of new radon detection technique and the study of radon (and of its progeny) time-dependece concentration in indoor locations. The final goal is to contribute to a radon survey in the granitic regions of Portugal and to a better understanding of radon exhalation and flow inside dwellings.
 
Candidate profile:
Master in Physics or Engineering Physics.
Good general experimental skills.
Good skills in instrumentation development and electronics.
Solid knowledge of scientific computation techniques.
 
Does this proposal involve more than one University?:
no
 
Synergies between the two Universities participating in the proposal:
DAEPHYS strongly encourages the presentation of thesis projects in co-supervision by researchers from two of the universities participating in the Program. In this field, explain the benefits resulting from the proposed co-supervision and the involvement of elements from the two universities, e.g. building critical mass teams, profiting from existing infrastructures or advanced equipments, profiting from expert technical know-how, etc. If the proposal involves only one University, write n/a.
(recommended length: 500-1000 char)
: n/a
 
Does this proposal involve a company?:
no
 
Proposals involving a company:
DAEPHYS strongly encourages the presentation of thesis projects involving a company, preferably a high-tech company. These proposals have to: 1) be centered on a technological problem in which the partner company has been (or plan / would like to be) involved; 2) have a co-supervisor on the enterprise; 3) include part of the project to be carried out in the company.
(recommended length: 500-1000 char)
:

 

Supervisor

Name:Luis Peralta
Institution:Faculdade de Ciências, Universidade de Lisboa
email:luis@lip.pt
 
link to CV or indication of ORCID ID:
orcid.org/0000-0002-3834-1762

 

Co-Supervisor

Name:Susana Barbosa
Institution:INESC-TEC: Porto, Portugal
email:susanabarb@gmail.com
 
link to CV or indication of ORCID ID:
orcid.org/0000-0003-2198-3715

 

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