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 017

Title:Development of fast pulse analysis algorithms for the GPU-based online monitoring system of the LZ dark matter search experiment
Objectives (recommended length: 2000-3000 char):
The tasks foreseen for this PhD project will be performed within the LUX-ZEPLIN (LZ) experiment, a detector designed for direct WIMP search using dual-phase xenon technology. They include the direct interaction with the detector data acquisition hardware and data pipeline, software development, development and application of data processing and analysis algorithms, and experimental activities during the detector installation and commissioning stages. During this project the student will be included in an international collaboration and work in key aspects of a state-of-the-art experiment, gaining the knowledge and experience required to become a successful physicist. The main objectives of the project can be summarised as follows:

Development of algorithms for various stages of a modular data processing and analysis framework, that will also be developed by the student. These include pulse finding and identification algorithms (to parameterise the different types of signals acquired in a double-phase xenon time projection chamber) and position reconstruction algorithms. Both the framework and the algorithms should be robust and modular to allow their extension to other types of detectors and fields of expertise (e.g. nuclear security and medical imaging);

Specialisation of the developed algorithms for use in an online analysis framework based on GPUs (Graphics Processing Units). This infrastructure will be responsible for onsite monitoring of the detector performance in real time to help detector operators to diagnose complex failure situations. There is currently a very active search for solutions based on GPUs in a broad range of commercial applications from medical imaging, security (identification of faces/objects), air traffic flow, radar signals, dynamic of molecules, etc.

As a starting point to the development and benchmarking of the algorithms described above, this PhD project includes the direct participation of the student in the installation and operations of the detector and the test system (a smaller chamber that is installed and operated at SLAC and used to inform and benchmark the final setup of the various subsystems of the detector).
The participation of the student in these on site tasks is of crucial importance not only for his/her full integration in the collaboration, but also to get the required insight of the hardware context which generates the input for the signal processing algorithms. It is therefore expected that he/she will be able to spend (up to 1 month) periods on site, in the Sanford Laboratory.
Upon completion of this PhD project, the student should have acquired a set of both hardware and software skills which overlap directly and naturally with the ones required not only in a wide range of nuclear science and medical imaging contexts, but also for industrial hardware monitoring and control.
Framework (recommended length: 500-2000 char):
There is a wide range of evidences from astrophysical and cosmological observations supporting the idea that ~80% of the matter in the Universe is made of an unknown form which does not emit or absorb light, the so called Dark Matter (DM). The nature of DM is one of the most important and interesting open scientific questions of our time, capable of attracting broad public attention. Moreover, the detection of DM would have a significant impact both on the observational astrophysics and cosmology and fundamental interactions.
The answer to the nature of the DM may lie in a generic class of Weakly Interacting Massive Particles (WIMPs). Distributed in halos surrounding galaxies, they should scatter off ordinary matter in terrestrial detectors. Various experiments are searching for these interactions using different techniques, but so far no clear evidence of a WIMP signal was found. The best limit currently published in the literature is from the LUX experiment, which uses a dual-phase xenon Time Projection Chamber (TPC). These results were received with wide interest, having collected nearly 1250 citations on Inspire-HEP. They were considered as "one of the year’s most important cosmological results" in Nature’s 2013 Year Review.
Merging LUX and ZEPLIN-III, the LUX-ZEPLIN (LZ) collaboration is currently designing a 10-ton xenon TPC which incorporates important enhancements to this already proven design concept, reaching a sensitivity >100 times better than the current LUX result. The collaboration (of which LIP is a founding member) has 200 members from 30 institutions (in the USA, UK, Portugal, Russia and South Korea), and is one of only three next generation DM direct detection experiments funded in the US.
The PhD student will be integrated in the LZ collaboration with the support of the LIP team, which has an accumulated successful experience in the design, development and operation of hardware and software tools for the control and exploitation of Xe TPCs
Tasks (recommended length: 1000-3000 char):
This PhD thesis project comprises a set of tasks which evolve naturally from the involvement of the student in the setup and optimization of the data acquisition system of the LUX-ZEPLIN (LZ) detector, to the characterisation and analysis of its output signals. It must be emphasized that the participation in onsite hardware activities is of crucial importance not only for the full integration of the student within the LZ collaboration but also to gain the required insight of the hardware context which generates the input for the signal processing algorithms:

1. Participation in the setup, optimisation and characterisation of the full signal acquisition chain (i.e. signal amplification, conditioning and digitization) of the experiment. Given the time frame for the installation of the LZ detector (2-3 years), the student will first work on these same tasks for the test system of the detector which will be installed and operated at SLAC to develop and benchmark the various subsystems of LZ. This will allow the student to have an early knowledge of the acquisition hardware and collect test data for the development of the algorithms described below. This task implies periods of onsite work (up to 1 month at a time) at SLAC (for work in the test system) and the Sanford Underground Laboratory (during the installation and commissioning stages of the detector);

2. Development and implementation of a software framework for benchmarking and optimising algorithms for the LZ online data monitoring system. This framework should follow a plug-in architecture and be versatile enough to extract and analyse relevant data not only from the LZ experiment but also from other types of detectors and fields of expertise (e.g. medical imaging, nuclear security);

3. Development and testing of pulse finding and parameterisation algorithms. As in any detection system, the correct identification and parameterisation of the signals acquired by the detector is of the utmost importance as this is the basis for all subsequent higher level analysis (e.g. position reconstruction). The algorithms will be used in the framework developed in step 2, and thus should be robust to allow an extension to other applications;

4. The ability to react in real time to evidences of malfunctioning of a detector as complex as LZ is seriously constrained by the time involved in transferring and analysing its data. This is particularly relevant during the commissioning stage -- when operational parameters are being optimised -- but also for stability monitoring during the long WIMP search period. To tackle this problem, the student will work on extending the framework (step 1) and in the specialization of the developed algorithms (step 2) to use GPUs (Graphics Processing Units). This infrastructure will be responsible for monitoring the detector performance in real time, improving the quality of the information available to the onsite crew and helping in the early detection of failures.
Research centre/lab or R&D unit hosting the thesis project:
University to which the thesis project will be presented:
UC - Universidade de Coimbra
DAEPHYS Scientific Domain in which the project fits:
Relation of the project to the Scientific Domains of DAEPHYS:
The project clearly fits within the area of instrumentation, aiming at the development of advanced signal analysis techniques with a broad spectrum of application outside the field of Dark Matter search (e.g. medical imaging, nuclear security) - which also enhances the potential for publication. Moreover, the development of a fast analysis framework (for online data quality monitoring) based on GPUs will endow the student with deep knowledge in a very active area with novel uses in a broad range of commercial applications (medical imaging, security, air traffic flow, radar signals, dynamic of molecules, etc.). The student will be included in an international collaboration and work in a state-of-the-art detector with the potential of finding Dark Matter, supported by a team with a large experience in all aspects of this type of detector. He/she will participate in the setup and optimization of the signal processing chain and acquire the data used in the development of the analysis tools
Candidate profile:
Master degree in Physics, Physics Engineering or similar, with interests in instrumentation, data analysis and software development.
Does this proposal involve more than one University?:
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)
Does this proposal involve a company?:
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)



Name:Alexandre Lindote
Institution:LIP-Coimbra and University of Coimbra
link to CV or indication of ORCID ID:



Name:Francisco Neves
Institution:LIP-Coimbra and University of Coimbra
link to CV or indication of ORCID ID:


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