Post-doctoral fellow in Experimental Particle Physics on the Light Dark Matter eXperiment (LDMX)

JOB SPECIFICATION             

The LDMX group at Lund University seeks a skilled and motivated post-doctoral fellow to join our research team in our efforts to get LDMX online and make the most of its data.

Subject description

Introduction

The Light Dark Matter eXperiment is a fixed-target experiment planned at SLAC with the main purpose of searching for sub-GeV thermal-relic dark matter particles produced from an 8 GeV electron beam impinging on a thin target. The Lund LDMX group (LunDMX) contributes to physics analysis, detector development and performance studies as well as software development and computing. In addition, we are active in addressing sustainability questions related to developing a new particle physics experiment.

Project description

The overarching theme of this project is to get ready for LDMX data, and the work will be conducted in close connection with the international LDMX collaboration, in which Lund University is the only non-US participant for the time being. One exciting milestone for LDMX is a beam test planned at SLAC in 2025, for the first time collecting data at the actual beam line for LDMX. During the first year, roughly, this project will be focused on the gathering and in particular on the analysis of this test beam data, mainly from the prototype of the hadronic calorimeter.

Another priority in this project will be to study the capabilities of LDMX to handle pile-up (multiple electrons hitting the target at the same time) in more detail. This will mainly be based on simulations studies of potential backgrounds, detector performance, and physics sensitivities. One concrete example is the use of different codes for simulating critical backgrounds, to compare these predictions and to develop methods for how to measure these backgrounds in data. The project also aims to explore to which extent machine learning methods can help with these tasks, e.g. object reconstruction and signal vs background discrimination. This will become more of a focus  later in the project.

There is some flexibility in the research programme for this position, and details can be tailored to your specific interests and expertise. There will also be the opportunity to work with questions of climate sustainability in LDMX/HEP, if that is something you are interested in.

The local environment

This postdoc position will be part of the Lund LDMX group (LunDMX, The Light Dark Matter eXperiment, LDMX), embedded in the division for particle and nuclear physics  at the physics department, Division of Particle and Nuclear Physics. The division with about 60 employees comprises a lively mixture of active research in theoretical and experimental particle and heavy ion physics as well as experimental nuclear physics. The experimental particle physics activities include research at the well-established LHC experiments ATLAS and ALICE as well as efforts to realise new, creative experiments like HIBEAM/NNBAR at ESS and – most relevant for this project – LDMX at SLAC (https://confluence.slac.stanford.edu/display/MME/Light+Dark+Matter+Experiment). We exploit synergies across these projects, and our contributions include detector development, trigger and DAQ, physics and performance analysis as well as software development and computing.  The LunDMX group currently consists of a senior researcher, three faculty members and two Ph.D. students. This postdoc position is an important addition to our group, it will inject additional momentum to our work and strengthen our impact on the overall LDMX project. This position is also to serve as a steppingstone for the successful candidate, with ample opportunity for career development, for which we strive to give all the support we can.   

Work duties

As a postdoc in the LunDMX group, you will take a prominent role in the test beam campaign in 2025 as well as the subsequent data analysis. Beyond that, you will perform simulation-based studies of different aspects feeding into the physics potential of LDMX. This will require the use (and further development) of different simulation tools, mainly the GEANT4-based ldmx-sw framework, https://github.com/LDMX-Software/ldmx-sw, written in C++, maintained on github and configured via python. You will work with .root files and explore different event generators as well as machine learning tools and algorithms. The position will also require you to contribute to the development of data-driven methods.

The nature of LDMX as an international project will require you to work collaboratively in an international research environment. Your main place of work will be at the Physics Department in Lund, but trips to SLAC/our collaborators will also be necessary. The position requires clear and thoughtful communication, both within the scientific community and with the public.
You will contribute to the development and maintenance of the common LDMX software.
You will be responsible for documentation and reporting of your research activities, maintaining detailed records of your work, preparing documentation for future users and following the LDMX requirements for contributing to documentation.
You are expected to participate in mentorship and training of junior researchers, fostering a collaborative and knowledge-sharing environment.
You will be given the opportunity to seek external research funding for travel or small projects, as well as to contribute to sustainability studies, if you wish to.
Your tasks will also include taking care of administration related to the duties outlined above.  

Qualification requirements

Appointment to a post-doctoral position requires that the applicant has a PhD, or an international degree deemed equivalent to a PhD, within the subject of the position, completed no more than three years before the date of employment decision. Under special circumstances, the doctoral degree can have been completed earlier.

Candidates who expect to defend their dissertations within the next six months are invited to apply. The candidate must have completed their doctoral degree before the position may begin.

Additional requirements:

• Prior experience with simulations and data analysis in particle physics or similar
• Strong programming skills in C++ and Python
• Prior experience in development and maintenance of common software
• Collaborative skills in order to work in an international collaboration.
• Very good oral and written proficiency in English
• Scholarly proficiency, for example demonstrated through published papers and/or the quality of your PhD dissertation.
• Preparedness for international travel
• You should be self-motivated, able to work self-sufficiently, and show initiative

Highly desirable qualifications:

Below follows a list of qualifications that should be read as “and/or”, not “and” – if you fulfil any of the listed requirements, it is a plus, but we do not expect you to tick all the boxes simultaneously.

• Prior experience in test beam measurements and/or hardware tests
• Good working knowledge of Geant4
• Prior experience with MCNP and/or FLUKA and/or PHITS
• Knowledgable about interactions in the borderland energy regime between nuclear and particle physics 
• Experienced in developing algorithms such as particle identification, specific final state event selection, and object reconstruction
• Experience in code performance analysis and optimisation
• Prior experience with machine learning tools
• Interest and prior experience in student supervision (bachelor, master, PhD)

Assessment criteria and other qualifications

This is a career development position primarily focused on research. The position is intended as an initial step in a career, and the assessment of the applicants will primarily be based on their research qualifications and potential as researchers. Particular emphasis will be placed on research skills within the subject.

For appointments to a post-doctoral position, the following shall form the assessment criteria:

• A good ability to develop and conduct high quality research.
• Teaching skills.

Additional assessment criteria:

• Relevance and viability of past and future research interests.
• Experience with particle physics data analysis and simulations
  • Experience in developing algorithms such as particle identification, specific final state event selection, and object reconstruction is considered a merit
  • Prior experience with machine learning tools is considered a merit
• Experience with particle physics detector tests and performance studies
• Proficiency in programming languages such as C++ and Python and working within large software frameworks.
  • Experience with Geant4, FLUKA, MCNP or PHITS is considered a merit.
  • Experience in code performance analysis and optimisation is considered a merit
• Experience working in an international collaboration.
• Interest and experience guiding others, particularly students, in their projects.

Evaluation of the applicants will take their experience, knowledge, and other personal qualities into consideration.

Consideration will also be given to good collaborative skills, drive and independence, and how the applicant’s experience and skills complement and strengthen ongoing research within the department, and how they stand to contribute to its future development.

Terms of employment

This is a full-time, fixed-term employment of two years with the possibility of a one-year extension. The period of employment is determined in accordance with the agreement “Avtal om tidsbegränsad anställning som postdoktor” (“Agreement on fixed-term employment as a post-doctoral fellow”) between Lund University, SACO-S and OFR/S, dated 1st February 2022.

Instructions on how to apply

Applications are submitted via the university’s recruitment system. Applications shall be written in English and contain (as pdf):

• A cover letter motivating your interest in this position and how this position matches your qualifications
• A statement of your current and future research interests (up to three pages)
• A CV with copies of PhD and exam certificates. You may supply a written statement with their expected defence date.
• A list of up to 10 relevant publications, annotated with your contributions
• A list with contact information for three references
  • Letters of recommendation are not requested at this time
  • References will be contacted if a candidate is invited to interview and with the candidate’s knowledge
• Any other documents the applicant wishes to submit for review 

Welcome with your application!