Postdoctoral position in fast-neutron dosimetry and reference neutron fields Full-time

Postdoctoral Position in Fast-Neutron Dosimetry and Reference Neutron Fields

Are you interested in working with fast neutrons, neutron dosimetry and detector characterisation, with the support of competent and friendly colleagues in an international environment? Are you looking for an employer that invests in sustainable employeeship and offers safe, favourable working conditions? We welcome you to apply for a postdoc position at Uppsala University.

The position is placed at the Division of Applied Nuclear Physics. We connect fundamental nuclear physics research with applications in nuclear technology and radiation safety. Examples of our research areas are experimental studies of nuclear fission, neutron spectrometry for plasma diagnostics in fusion, nuclear data evaluation methodology, and technical aspects of nuclear safeguards and disarmament. The division operates NESSA, a 14 MeV neutron facility in the FREIA hall at the Ångström Laboratory. Since November 2025, NESSA has been equipped with a D-T neutron generator delivering up to 10⁸ neutrons per second, making it a unique facility in Sweden and the Nordic region.

The position is funded by the Swedish Radiation Safety Authority (SSM) within the project “A Reference Neutron Field at Uppsala for Detector Response, Dosimetry and Cross-Calibration in Support of Radiation Protection and Preparedness”. The project will establish and characterise a variable-energy reference neutron field at Uppsala, based on 14 MeV neutrons from NESSA and complemented by charged-particle-induced neutron fields at the Uppsala Tandem Laboratory, and link the measurements to the European metrology chain. The results will strengthen national competence in radiation protection and emergency preparedness.

Duties

You will carry the experimental and computational work of the project within the NESSA team, including:

• building and validating Monte Carlo models of the NESSA bunker and the detector systems using several codes, e.g. MCNP, FLUKA, Geant4, PHITS and FISPACT-II;
• commissioning and operating a detector suite consisting of, e.g., liquid scintillators with pulse-shape discrimination, micro fission chambers, and activation foils analysed by HPGe gamma-ray spectrometry;
• characterising the neutron fields in terms of energy spectra and fluence with full uncertainty budgets;
• performing shielding and moderation experiments (e.g. polyethylene and concrete) and benchmarking the results against simulations;
• measuring detector response functions in neutron fields at the Uppsala Tandem Laboratory;
• planning and carrying out a cross-calibration campaign at a reference neutron fields (e.g. PTB Braunschweig);
• publishing the results in peer-reviewed journals and international conferences;
• contributing to education and training in neutron measurement techniques for students and for staff from authorities and industry.

We also encourage you to develop your own research profile and to contribute to applications that help develop the activities of the division.

Requirements

PhD degree in physics or a related field, or a foreign degree equivalent to a PhD degree in physics or a related field. The degree needs to be obtained by the time of the decision of employment. Priority will be given to applicants who have completed their degree no more than three years before the deadline for applications. Due to special circumstances, the degree may have been obtained earlier. The three-year period can be extended due to circumstances such as sick leave, parental leave, duties in labour unions, etc.

You must have documented experience in experimental nuclear or radiation physics, for example neutron measurements, radiation detectors or dosimetry, as well as experience in Monte Carlo simulation of radiation transport. Very good communication skills in spoken and written English are required. We are looking for someone who is structured and thorough, who can work independently and drive an experimental project forward, and who collaborates well with others.

Additional qualifications

The qualifications listed below are meant to help you point out relevant experience and expertise. We strongly encourage you to apply even if your experience does not match all of them:

• Experience in experimental techniques using fast neutrons.
• Experience with liquid scintillators and pulse-shape discrimination, fission chambers, or digital data acquisition.
• Experience in neutron spectrometry and neutron dosimetry, e.g. Bonner sphere spectrometry and spectrum unfolding methods.
• Experience with neutron activation techniques and HPGe gamma-ray spectrometry.
• Proficiency in one or more of the codes MCNP, FLUKA, Geant4, PHITS and FISPACT-II.
• Experience in uncertainty analysis and metrology.
• Experience with experiments at accelerators or other neutron sources.

About the employment

The employment is a temporary position of two years according to central collective agreement. Full time position. Starting date 1 February 2027 or as agreed. Placement: Ångström Laboratory, Uppsala.